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This paper deals with new approaches towards the Jablonski diagram and the ¿ state concepts from the viewpoint of the relationship between electronic deactivation and vibrational relaxation processes in electronically excited species. In both concepts, vibrational relaxation precedes the electronic deactivation processesofexcited molecules. The experimental data accumulated up to the present using mainly time-resolved luminescence and transient absorption spectroscopy from the field of the photophysics of transition metal compounds and different organic molecules have clearly demonstrated that even spin-forbidden electronic deactivations are in many cases faster processes that vibrational relaxation. It means that the classical Jablonski diagram indicating that electronic deactivation processes occur after vibrational relaxation should be modified. In general, electronic deactivations occur from vibrationally higher states. [ABSTRACT FROM AUTHOR]

The present contribution evaluates the methods of degradation and stabilization of alum-containing paper with a focus on the alkaline environment achieved by deacidification procedures. In terms of reviewed subjects, the contribution focuses on alum-rosin sized paper, which is still used as a carrier of knowledge and information; however, it also mentions cellulose itself and other brands of paper. The contribution summarizes the results on the homogeneity of the distribution of alum and rosin in the paper mass and on the paper surface. It provides the knowledge gained in the field of alkaline hydrolysis and oxidation with special regard to transition metal species. It shows the values of alkaline reserves achieved in the main mass-deacidification processes. On the basis of the acquired knowledge, the contribution emphasizes the procedures of paper stabilization. Criteria of "increased mechanical permanence and lifetime prolongation" adopted to evaluate and compare the efficacy of individual mass-deacidification processes were applied and corresponding data are introduced. The contribution also draws attention to the existence of open issues in the area of paper degradation and stabilization.

In Europe, the use of aluminium(III) compounds, namely AlK(SO 4 ) 2 ·12H 2 O and later on Al 2 (SO 4 ) 3 ·18H 2 O for hardening gelatin sizes was recorded as early as the 16th century. This review is focused on the critical assessment of published data concerning the following chemical aspects of paper degradation: direct influence of H 3 O + ions formed during hydrolysis of aluminium(III) species; influence of low-molecular organic acids formed within degradation processes; influence of pH variation on the redox potential of reactive oxygen species acting as oxidizing agent; consequences of the absorption of gaseous NO 2 and SO 2 present in the air for paper degradation; involvement of aluminium species in redox radical oxidation catalytic processes; possible effect of the coordination of Al(III) with small radius and high charge on oxygen atoms of cellulose carboxyl or hydroxyl groups. It is indicated how the understanding of the above mentioned effects can help slow down paper degradation., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This review deals with two overlapping issues, namely polymer chemistry and deep eutectic solvents (DESs). With regard to polymers, specific aspects of synthetic polymers, polymerization processes producing such polymers, and natural cellulose-based nanopolymers are evaluated. As for DESs, their compliance with green chemistry requirements, their basic properties and involvement in polymer chemistry are discussed. In addition to reviewing the state-of-the-art for selected kinds of polymers, the paper reveals further possibilities in the employment of DESs in polymer chemistry. As an example, the significance of DES polarity and polymer polarity to control polymerization processes, modify polymer properties, and synthesize polymers with a specific structure and behavior, is emphasized.

The scientific community, experts in technology and marketing have been seeking cost-competitive and green solvents with good dissolving capacity for the valorisation of biomass and biowaste. Along with traditional solvents and techniques, deep eutectic solvents (DESs) and their bio-analogues, natural deep eutectic solvents (NADESs) are currently emerging as a new class of promising liquid media. In this review, a comprehensive summary of recent contribution of DESs to the processing and valorisation of various kinds of plant and animal based biomass and biowaste is provided. In the field of food industry based and agro-forest waste valorisation, through treatment of the waste, by-products, and natural materials by DESs, several types of compounds, such as flavonoids and other plant phenolics, phenolic acids, stilbenes, tannins, lignans, and lignin were obtained. Extraction of algae by DESs led to isolation mainly of proteins, carbohydrates, lipids and nucleic acids. Vegetable oils, spent oils, residues and by-products of their processing are a rich source of phenolic compounds such as phenolic acids and phenolic alcohols, secoiridoid derivatives (aglycone and ligstroside), lignans (pino and acetoxypinoresinol), flavones (luteolin and apigein), tocopherols and tocotrienols. Dietary fibre serves as a source of lignin, pectic substances, gums, resistant starch, inulin, as well as non-carbohydrate components, e.g., polyphenols, waxes, saponins, cutin, phytates, resistant proteins. Valorisation of wastes originated from animal processing by DESs means obtaining high-value chemicals including amino acids, proteins, bioactive peptides, collagen peptides, albumin etc. Through the valorisation of the mentioned waste types value-added products with potential applications in the pharmaceutical, food and cosmetic industries are produced. The paper gathered data on the used DESs, treated substances and obtained products, together with treatment conditions and the products yields. The evaluation of the state-of-the-art in the field of biowaste valorisation using DESs and NADESs led to conclusions and indication of future prospects and predicted development in this field., (Copyright © 2018 Elsevier B.V. All rights reserved.)