253 research outputs found

    Problems Encountered while Revising the Proverb Lore in a General Bilingual Dictionary

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    The revision of the proverb lore in the French-Hungarian and Hungarian-French Dictionary to be published in Hungary in the near future forced me to give quite quick and short answers to questions that should deserve due consideration, i.e.: – How to determine the quantity and quality of proverbs that should be included in a (nonphraseological) bilingual dictionary? – How to deal with proverbs no equivalent of which is known in the other language? – To what extent are details needed/permitted about the different uses of individual proverbs? – Under what and how many key words should a proverb appear? – Should we suppress the distinction between the labels proverb and proverbial expression because of the relationship between them? – When the entry is divided into several parts for semantic or grammatical reasons, should we place the proverbs separately at the end of each part or together at the end of the entry? I have no universal answer to these questions, but I may contribute to the reflection by giving some ideas

    The Effect of Acidic Ternary Deep Eutectic Solvent Treatment on Native Lignin

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    Ternary deep eutectic solvents (DESs) are gaining increased attention to serve as a cheap green alternative medium for the processing of lignocellulosic biomass. For example, mixtures of choline chloride (ChCl), ethylene glycol (EG), and oxalic acid (OA) were recently explored for the fractionation of lignocellulosic biomass into its main components. Interestingly, during this processing, the recovered lignin was structurally modified by incorporation of EG, which altered its solubility properties and led to the need for different lignin recovery strategies. This offers an excellent starting point for a deeper investigation of the effect of acidic DES systems on the structure of lignin. In particular, native-like residual enzyme lignins (RELs) that are hard to completely dissolve in organic solvents are specifically suitable for this task. Here, a ternary DES is used consisting of ChCl/EG with OA or trifluoromethanesulfonic acid (HOTf) as a third component. The results showed that both solvent systems led to high EG incorporation into REL. The HOTf system showed a lesser extent of lignin depolymerization at similar modification levels as it already induced modification at lower temperature (25–30 °C). Low recovery yields from typical acidic precipitation were observed for treatment with both acidic DES systems. Analysis of THF and DCM extracts showed that the products in the water phase included small EG modified lignin fragments and aromatic monomers released from lignin aryl ether linkage cleavage. This analysis details the types of other products that can be expected and where these will end up during fractionation. These results show that the treatment of lignin with acidic DES in the presence of alcohols leads to low- and high-molecular-weight products that are not effectively recovered by typical precipitation procedures

    Pre-treatment of lignocellulosic feedstocks using biorenewable alcohols::towards complete biomass valorisation

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    Here, we report on the ability of the biomass derived solvents ethanol and, in particular, n-butanol to fractionate lignocellulose into its main components. An organosolv system consisting of n-butanol containing 5% water and 0.2 M HCl at reflux was found to remove effectively the lignin and hemicellulose components of lignocellulosic biomass leaving a cellulose pulp suitable for enzymatic hydrolysis to simple sugars. Using a hardwood beech pulp as an example, essentially complete conversion of the cellulose component to reducing sugars was achieved with a cellulase loading of 22 FPU per g. Analysis of the solubilised hemicellulose fractions revealed that they consist almost exclusively of alkyl xylosides and mannosides which could serve as valuable synthetic building blocks. Additionally, the mild conditions (<120 °C) and high alcohol content of the pre-treatment solvent suppressed lignin degradation reactions and allowed for the isolation of high quality lignins in good yields. Detailed HSQC NMR analysis of the isolated lignins revealed that they still contained large amounts of β-aryl ether units, especially α-ethoxylated and α-butoxylated β-O-4 units, making them particularly suitable for depolymerisation to mono-aromatic chemicals. This was demonstrated using a recently reported acidolysis method utilizing ethylene glycol which gave monomer yields of between 7.4 and 18 wt%. The yields for n-butanol lignins were at least four fold higher than those obtained from a current generation technical organosolv lignin under comparable conditions

    Chemicals from lignin by diol-stabilized acidolysis:Reaction pathways and kinetics

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    The product selectivity, production rates and the required process conditions are important for technology development. Selective lignin depolymerisation on the prime β-O-4 motif provides an opportunity to obtain valuable functionalized phenolic monomers. Diol-stabilized acidolysis of lignin with sulfuric acid, triflic acid or triflate salts is a proven β-O-4 cleavage methodology that forms acetals by trapping of released reactive aldehydes. For future scale-up, a better understanding of the prime reaction pathways and how these can be controlled upon changing reaction parameters is required. By using β-O-4 model compounds and ytterbium(iii) triflate as catalyst, starting material conversion and product formation including two key intermediates, the diol adducts (in this study, ethylene glycol as the diol) and the vinyl ethers, were accurately monitored, allowing for detailed kinetic modelling. Over the selected temperature range (80-150 °C), higher temperatures led to higher overall carbon balance and selectivity for the main desired acetal product. The kinetic modelling allowed for establishing a detailed reaction network with activation energies and rate constants. These collectively led to new insights into the key steps involved in the diol-stabilized β-O-4 motif acidolysis and how the reaction selectivity can be manipulated by controlling the reaction temperature, and the ethylene glycol and water content. The elucidation on reaction kinetics and networks constitutes a further step in the design of a diol-stabilized lignin acidolysis process

    Erratum:New mechanistic insights into the lignin β-O-4 linkage acidolysis with ethylene glycol stabilization aided by multilevel computational chemistry (ACS Sustainable Chemistry and Engineering (2021) 9:5 (2388-2399)

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    In the Supporting Information of the original article (https://pubs.acs.org/doi/10.1021/acssuschemeng.0c08901), the x-axes in Figures S6c and d are wrongly labeled. It is stated that the reaction times are in “minutes”; however, the reaction times are actually in hours. Additionally, for Figure S6d, the indicated times are incorrect. A new Supporting Information file is provided here in which these mistakes have been corrected

    New Mechanistic Insights into the Lignin beta-O-4 Linkage Acidolysis with Ethylene Glycol Stabilization Aided by Multilevel Computational Chemistry

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    Acidolysis in conjunction with stabilization of reactive intermediates has emerged as one of the most powerful methods of lignin depolymerization that leads to high aromatic monomer yields. In particular, stabilization of reactive aldehydes using ethylene glycol results in the selective formation of the corresponding cyclic acetals (1,3-dioxolane derivatives) from model compounds, lignin, and even from softwood lignocellulose. Given the high practical utility of this method for future biorefineries, a deeper understanding of the method is desired. Here, we aim to elucidate key mechanistic questions utilizing a combination of experimental and multilevel computational approaches. The multiscale computational protocol used, based on ReaxFF molecular dynamics, represents a realistic scenario, where a typical experimental setup can be reproduced confidently given the explicit molecules of the solute, catalyst, and reagent. The nudged elastic band (NEB) approach allowed us to characterize the key intermolecular interactions involved in the reaction paths leading to crucial intermediates and products. The high level of detail obtained clearly revealed for the first time the unique role of sulfuric acid as a proton donor and acceptor in lignin beta-O-4 acidolysis as well as the reaction pathways for ethylene glycol stabilization, and the difference in reactivity between compounds with different methoxy substituents

    Enhancement of lung tumorigenesis in a Gprc5a Knockout mouse by chronic extrinsic airway inflammation

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    <p>Abstract</p> <p>Background</p> <p>Although cigarette smoking is the principal cause of lung carcinogenesis, chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, has been identified as an independent risk factor for lung cancer. Bacterial colonization, particularly with non-typeable <it>Haemophilus influenzae </it>(NTHi), has been implicated as a cause of airway inflammation in COPD besides cigarette smoke. Accordingly, we hypothesized that lung cancer promotion may occur in a chronic inflammatory environment in the absence of concurrent carcinogen exposure.</p> <p>Results</p> <p>Herein, we investigated the effects of bacterial-induced COPD-like inflammation and tobacco carcinogen-enhanced tumorigenesis/inflammation in the retinoic acid inducible G protein coupled receptor knock out mouse model (Gprc5a-/- mouse) characterized by late-onset, low multiplicity tumor formation. Three-month-old Gprc5a-/- mice received 4 intraperitoneal injections of the tobacco-specific carcinogen, NNK, followed by weekly exposure to aerosolized NTHi lysate for 6 months. The numbers of inflammatory cells in the lungs and levels of several inflammatory mediators were increased in Gprc5a-/- mice treated with NTHi alone, and even more so in mice pretreated with NNK followed by NTHi. The incidence of spontaneous lung lesions in the Gprc5a-/- mice was low, but NTHi exposure led to enhanced development of hyperplastic lesions. Gprc5a-/- mice exposed to NNK alone developed multiple lung tumors, while NTHi exposure increased the number of hyperplastic foci 6-fold and the tumor multiplicity 2-fold. This was associated with increased microvessel density and HIF-1α expression.</p> <p>Conclusion</p> <p>We conclude that chronic extrinsic lung inflammation induced by bacteria alone or in combination with NNK enhances lung tumorigenesis in Gprc5a-/- mice.</p

    Investigating the complex story of one ditch — A multidisciplinary study of ditch infill provides insight into the spatial organisation within the oppidum of Bibracte (Burgundy, France)

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    Seemingly empty spaces in various archaeological settings have left many unanswered questions. This paper focuses on the appearance, maintenance and possible function of a large empty area situated at the summit plateau of the Iron Age oppidum Bibracte in France. Multidisciplinary research of the infill of the ditch that delimited this area in the 1st century BC has provided evidence on the primary function and the formation processes of the structure itself, and for the reconstruction of the appearance, maintenance and function of the area it enclosed. The results allow us to gain insight into a variety of topics, including the role of trees, hygiene measures and waste management strategies at this urbanised hilltop centre. This paper demonstrates that multi-proxy analyses provide detailed insight into the function of archaeological features in a local environmental context and the potential of such approaches in archaeology.U domněle prázdných(nezastavěných) míst v archeologickém kontextu je řada nezodpovězených otázek. Článek se zaměřuje na vzhled, způsob udržování a možnou funkci velkého prázdného prostoru v době železné v rámci vrcholového plateau oppida Bibracte ve Francii. Multidisciplinární přístup k výzkumu výplně příkopu, který tento prostor vymezoval v 1. století př. Kr., poskytl doklady o primárním využití a vzniku výplně v příkopu a dále k rekonstrukci vzhledu, managementu a funkce území, které jej obklopovalo. Výsledky nám umožňují vhled do řady témat, včetně role stromů, úrovně hygieny a nakládání s odpadem v urbanizovaném prostředí oppida. Článek prokazuje důležitost multi-proxy přístupu pro řešení funkce archeologických objektů v lokálním environmentálním kontextu a potenciál tohoto přístupu v archeologii

    Tunable and functional deep eutectic solvents for lignocellulose valorization

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    Stabilization of reactive intermediates is an enabling concept in biomass fractionation and depolymerization. Deep eutectic solvents (DES) are intriguing green reaction media for biomass processing; however undesired lignin condensation is a typical drawback for most acid-based DES fractionation processes. Here we describe ternary DES systems composed of choline chloride and oxalic acid, additionally incorporating ethylene glycol (or other diols) that provide the desired ‘stabilization’ function for efficient lignocellulose fractionation, preserving the quality of all lignocellulose constituents. The obtained ethylene-glycol protected lignin displays high β-O-4 content (up to 53 per 100 aromatic units) and can be readily depolymerized to distinct monophenolic products. The cellulose residues, free from condensed lignin particles, deliver up to 95.9 ± 2.12% glucose yield upon enzymatic digestion. The DES can be recovered with high yield and purity and re-used with good efficiency. Notably, we have shown that the reactivity of the β-O-4 linkage in model compounds can be steered towards either cleavage or stabilization, depending on DES composition, demonstrating the advantage of the modular DES composition
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