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The moisture resistance of friction-welded wood joints can be improved by applying bio-based bonding additives. Several biomolecules including tannic acid, organosolv lignin from hardwood, kraft lignin from softwood, and derivates thereof, were investigated regarding their applicability as bonding additives in the friction welding process. Welding with kraft lignin showed significantly increased moisture stability after 24 h water immersion. An average wet bond strength of 1.5 MPa compared to 0.38 MPa of untreated spruce was obtained. Modification of kraft lignin through succinylation, acetylation or depolymerisation led to no further improvement in moisture stability. Depolymerised kraft lignin resulted in an even higher delamination rate of the samples during water immersion than untreated samples. Structural analysis of the lignin variations by FTIR-ATR, GPC and 31P NMR in combination with thermal analysis by TGA and DSC showed the impact of various structural and chemical features on the thermal behaviour and intermolecular interactions of the applied lignin. [ABSTRACT FROM AUTHOR]

Microcapsules (MCs) and nanoemulsions (NEs) were generated from both condensed and hydrolysable tannins, respectively, for controllable, stimuli-responsive active release. A rapid, simple and robust one step method based solely on the use of tannins, i.e., without the use of any additional cross-linking reagents, was developed via ultrasound treatment. The condensed tannins Schinopsis balansae wood extract (Sb) and Acacia mearnsii bark extract (Am) were studied for their potential use in microcapsule assembly, and the hydrolysable tannins tannic acid (TA) and epigallocatechin-3-O-gallate (EGCG) were studied for their potential use in forming nanoemulsions upon ultrasonic irradiation. Tannin microcapsules (TMCs) and tannin nanoemulsions (TNEs) were thoroughly characterized via cryo-SEM, as well as fluorescence and optical microscopy, to reveal their structural and morphological characteristics. GPC analyses revealed that microcapsules and nanoemulsions were formed due to efficient electronic interactions between the aromatic moieties present in the polyphenolic backbone of high molecular weight fractions of tannins, and apparently without any significant chemical modification. Both TMCs and TNEs were formed in high yields and their release efficiencies showed the higher stability of the MCs compared to the NEs. Active release from and the pH stability of both the TMCs and TNEs were evaluated. Tannins – and more specifically the polymeric structures of tannins – proved to be ideal scaffolds for ultrasound assisted capsule assembly with potential for the pH triggered delivery of hydrophobic active molecules. [ABSTRACT FROM AUTHOR]

Two constitutional structural schemes are proposed attempting to unify and rationalize a series of focused NMR and chromatographic determinations aimed at providing an integrated picture for the structure of softwood kraft lignin. The complexity of native softwood lignin when coupled with the complexity of the kraft pulping process is known to lead to a rather heterogeneous material that has eluted us to date. The present work embarks at applying state-of-the-art quantitative 1D and 2D NMR methods on carefully isolated softwood kraft lignin samples and fractions. The accumulated data, when coupled with size exclusion chromatography, mass spectrometric analyses and literature accounts that pertain to the chemistry of kraft pulping, provide the following picture for softwood kraft lignin. Softwood kraft lignin is composed of two distinct fractions that can be separated by using anhydrous acetone. The acetone insoluble fraction is a somewhat branched polymeric material that still contains a variety of native wood lignin bonding patterns, albeit in significantly reduced abundance, as well as new structures induced during the process. The acetone soluble fraction is a significantly more branched and less polymeric material with an abundance of chemical structures that may be created when oligomeric phenols react under kraft pulping conditions. To account for the presence of the various moieties in these two fractions, kraft pulping fragmentation and repolymerization chemistries are extensively invoked, including radical processes initiated by sulfur. [ABSTRACT FROM AUTHOR]

Organosolv lignins (OSLs) are important byproducts of the cellulose-centred biorefinery that need to be converted in high value-added products for economic viability. Yet, OSLs occasionally display characteristics that are unexpected looking at the lignin motifs present. Applying advanced NMR, GPC, and thermal analyses, isolated spruce lignins were analysed to correlate organosolv process severity to the structural details for delineating potential valorisations. Very mild conditions were found to not fractionate the biomass, causing a mix of sugars, lignin-carbohydrate complexes (LCCs), and corresponding dehydration/degradation products and including pseudo-lignins. Employing only slightly harsher conditions promote fractionation, but also formation of sugar degradation structures that covalently incorporate into the oligomeric and polymeric lignin structures, causing the isolated organosolv lignins to contain lignin-humin hybrid (HLH) structures not yet evidenced as such in organosolv lignins. These structures effortlessly explain observed unexpected solubility issues and unusual thermal responses, and their presence might have to be acknowledged in downstream lignin valorisation. Careful structural analyses of spruce organosolv lignin isolates by state-of-the-art techniques revealed a new structural component: humin-lignin hybrids. These novel structures can help to understand the complex interplay between the structural polymers during common biorefinery approaches, and can explain puzzling physico-chemical behaviours of organosolv lignins. [Display omitted] • Spruce lignins were isolated via a steam-explosion organosolv process. • Isolated lignins were analysed for structural features and thermal stabilities. • Data suggest that covalently linked lignin-humin hybrids are eventually formed. • Thermal stability profiles sustain the presence of such hybrid structures. [ABSTRACT FROM AUTHOR]

Salicylate and benzoate sunscreen agents have been encapsulated by the green, fast and robust ultrasound technique in tannin microcapsules (TMCs). The generated TMCs, obtained without use of cross linking agents, were fully characterised, including encapsulation efficiencies with respect to the encapsulated actives. Release kinetics of TMCs have been studied mimicking skin conditions. Body cream base samples containing specific concentrations of microcapsules filled with sunscreen actives were prepared and showed synergistic effects in terms of UV-protection abilities generated by the interplay between sunscreen actives and natural tannin polyphenols. The synergistic effect exerted by the tannin and the controlled active release allows to reduce the amount of synthetic sunscreens needed, and does thus contribute to the development of more sustainable and environmentally benign UV-protection systems. [Display omitted] • Sunscreen agents were encapsulated by a ultrasound technique in tannin microcapsules. • Release kinetics of TMCs have been studied mimicking skin conditions. • A synergistic effect by the tannin and the controlled active release was observed. • A sustainable and environmentally benign UV-protection system has been developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dissolution requires solute conformational flexibility. • Polysaccharide dissolution are restricted because of inflexible sugar ring. • Lignin dissolution is less hampered due to its dynamic aromatic nature. • Solute dissolution can be modified similarly through temperature or solvent. • Saturation is largely dictated by the potential energy minima of the bulk solvent. Lignocellulosic biomass is one of the most important renewable materials to replace carbon-based fossil resources. Solvent-based fractionation is a promising route for fractionation of biomass into its major components. Processing is governed by the employed solvent-systems properties. This review sheds light on the factors governing both dissolution and potential reactivities of the chemical structures present in lignocellulose, highlighting how proper understanding of the underlying mechanisms and interactions between solute and solvent help to choose proper systems for specific fractionation needs. Structural and chemical differences between the carbohydrate-based structural polymers and lignin require very different solvents capabilities in terms of causing and eventually stabilizing conformational changes and consequent activation of bonds to be cleaved by other active components in the. A consideration of potential depolymerization events during dissolution and energetic aspects of the dissolution process considering the contribution of polymer functionalities allow for a mapping of solvent suitability for biomass fractionation. [ABSTRACT FROM AUTHOR]

Tannase (EC 3.1.1.20) was quantitatively immobilised onto Eupergit® C 250 L and coated by layers of alternatively charged polystyrene sulfonate and polyallylamine hydrochloride, respectively. The layer-by-layer (LbL)-coated immobilised tannase, i.e. , LbL-tannase retained its original activity and showed significant resistance to deactivation and maintained 50% of its activity after seven consecutive cycles of hydrolysis reactions, each run for 24 h. The LbL coating did not hinder the substrate access to the active site of the enzyme. Both gallo- and ellagitannins were efficiently hydrolysed upon treatment with LbL-tannase. The formation of gallic acid and the reaction patterns were followed by HPLC and the recently developed 31 P NMR analytical method for the characterisation of tannins. [ABSTRACT FROM AUTHOR]

Two distinct functionalization schemes for Kraft lignin (KL) were developed to selectively incorporate furan and/or maleimide motifs as chain ends. The incorporation of furan functionalities was carried out by the selective and quantitative reaction of the lignin's phenolic OH groups with furfuryl glycidyl ether (FGE). Maleimide groups were introduced by esterifying the lignin's aliphatic and phenolic OH groups with 6 maleimidohexanoic acid (6-MHA), offering a high loading despite a somewhat incomplete conversion. Furan- and maleimide-functionalized lignins were subsequently combined to generate crosslinking via the Diels–Alder (DA) [4 + 2] cycloaddition reaction. The formation of the DA adduct was confirmed by 1H NMR. Under appropriate conditions, the formation of a gel was apparent, which turned back into the liquid state after performing the corresponding retro-DA reaction upon heating to 120 °C. This study reveals the significant versatility and potential of the developed strategy for the utilization of lignin-based recyclable networks. [ABSTRACT FROM AUTHOR]

Auf das Wasser kommt es an: Konservierte Bindungsgeometrie, enthalpiegetriebene Bindungsweise und nichtunterscheidbare Bindungsaffinitäten für fluorierte und nichtfluorierte Liganden von humaner Carbonsäureanhydrase (siehe Bild) stützen die Theorie, dass das Schlüssel ‐ Schloss ‐ Modell einen wichtigen Bestandteil des Bindungsvorgangs unbeachtet lässt: das Wasser, das die Bindungstasche des Proteins füllt und den Liganden umgibt. [ABSTRACT FROM AUTHOR]

It's the water that matters. Pairs of benzo‐ and perfluorobenzoarylsulfonamide ligands bind to human carbonic anhydrase with a conserved binding geometry, an enthalpy‐driven binding, and indistinguishable binding affinities (see picture). These data support the pervasive theory that the lock‐and‐key model disregards an important component of binding: the water, which fills the binding pocket of the protein and surrounds the ligand. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lignin can be obtained in large quantities from renewable resources. [•] Lignin can be oxidatively upgraded and depolymerised by catalytically activated molecular oxygen or hydrogen peroxide. [•] Organometal species, biomimetic compounds, and enzymes can be used as catalysts. [•] Many of the catalysts, including the enzymes, can be polymer-supported. [•] Product mixtures can be influenced by tuning catalysts and underlying mechanisms. [ABSTRACT FROM AUTHOR]

A supported version of N-(tert-butyl)phenylsulfinimidoyl chloride on a monolithic material is described, which can be incorporated into a flow chemical processing arrangement to oxidise a variety of substrates in both stoichiometric and catalytic processes to yield products in high yields and in high purity after in-line workup. [ABSTRACT FROM AUTHOR]

Abstract: Enantioenriched α-stannylated benzyl carbamates were used in highly stereospecific coupling reactions employing Cu(I) as catalyzing transition metal. Acid chlorides and allyl bromide derivatives were used as electrophilic coupling partners. The reaction was applied in the synthesis of two highly enantioenriched indanoles and one enantioenriched tetraline via intramolecular cyclization reactions. [Copyright &y& Elsevier]

Both condensed and hydrolysable tannins represent versatile natural polyphenolic structures exhibiting a broad range of activities that could be exploited in various fields including nutraceutics, cosmesis, consumer care, household and pharmaceutical applications. Various tannins are commercially available nowadays for use in such application fields. We have analysed a representative selection of commercially available condensed and hydrolysable tannins for structural features and purity. Using a combination of quantitative 31P NMR spectroscopy, HSQC measurements, MALDI-ToF analyses, gel permeation chromatography and wet chemical analysis, detailed structural characterisations and descriptions were possible, allowing for verification and falsification of claimed structural features. [ABSTRACT FROM AUTHOR]

Thymol and the corresponding brominated derivatives constitute important biological active molecules as antibacterial, antioxidant, antifungal, and antiparasitic agents. However, their application is often limited, because their pronounced fragrance, their poor solubility in water, and their high volatility. The encapsulation of different thymol derivatives into biocompatible lignin-microcapsules is presented as a synergy-delivering remedy. The adoption of lignosulfonate as an encapsulating material possessing relevant antioxidant activity, as well as general biocompatibility allows for the development of new materials that are suitable for the application in various fields, especially cosmesis. To this purpose, lignin microcapsules containing thymol, 4-bromothymol, 2,4-dibromothymol, and the corresponding O-methylated derivatives have been efficiently prepared through a sustainable ultrasonication procedure. Actives could be efficiently encapsulated with efficiencies of up to 50%. To evaluate the applicability of such systems for topical purposes, controlled release experiments have been performed in acetate buffer at pH 5.4, to simulate skin pH: all of the capsules show a slow release of actives, which is strongly determined by their inherent lipophilicity. [ABSTRACT FROM AUTHOR]

Eucalyptus nitens wood samples were subjected to consecutive stages of hydrothermal processing for hemicellulose solubilization and delignification with an ionic liquid, i.e., either 1-butyl-3-methylimidazolium hydrogen sulfate or triethylammonium hydrogen sulfate. Delignification experiments were carried out a 170 °C for 10–50 min. The solid phases from treatments, i.e., cellulose-enriched solids, were recovered by centrifugation, and lignin was separated from the ionic liquid by water precipitation. The best delignification conditions were identified on the basis of the results determined for delignification percentage, lignin recovery yield, and cellulose recovery in solid phase. The lignins obtained under selected conditions were characterized in deep by 31P-NMR, 13C-NMR, HSQC, and gel permeation chromatography. The major structural features of the lignins were discussed in comparison with the results determined for a model Ionosolv lignin. [ABSTRACT FROM AUTHOR]

Catalytic enantioselective Strecker reactions on an achiral substrate using sub-stoichiometric amounts of a chiral catalyst represent an evolving key strategy for the effective synthesis of α-amino nitriles. We herein disclosed the set-up of a flow-based methodology for enantioselective Strecker, employing ethyl cyanoformate as a relatively safe cyanide source, a cinchona-based catalyst, and methanol as additive. A thorough exploration of key parameters allowed the identification of the most efficient reagent mixing mode, the optimum solvent for the flow synthesis, minimum catalyst loading, additive, temperature, and residence time. The newly developed method allows straightforward reaction channeling towards the fast and complete formation of the α-amino nitrile products, thus reducing the yield drop due to indolenine degradation during long-lasting batch-wise reactions. Moreover, we herein provide preliminary hints for sustainability, by proposing a simple procedure for catalyst recycling, thus opening the way for further optimization of the proposed methodology. [ABSTRACT FROM AUTHOR]

Privileged scaffolds as starting points toward biologically active molecules represent a neuralgic point in drug discovery. The ability of synthetic chemists concerned with their generation should be flanked by robust technologies enabling the efficient synthesis and decoration of large libraries for extensive screenings and for scale-up processes. The use of continuous flow chemistry in the pharmaceutical chemistry sector may facilitate privileged scaffold generation and implementation of more efficient multistep transformations which can contribute to developing green and sustainable processes. This review discusses the use of flow chemistry applied to the synthesis of privileged scaffolds, considering also sustainability and green chemistry aspects. Flow protocols are discussed in a unified fashion such as to facilitate effective comparison between both the various chemical approaches used on the one hand, and the chosen technical solutions across the various works on the other hand. The review also offers an authors' perspective on potential future directions in the field. [ABSTRACT FROM AUTHOR]

Lignin nanoparticles (LNPs) are considered as intriguing green, renewable alternatives to fossil-based nanomaterials. However, the predisposition of LNPs to dissolve under alkaline conditions makes covalent surface functionalisation in the dispersion state difficult and limits applications demanding morphological stability under challenging pH conditions. Mechanistic studies suggest that during the formation of LNPs by nanoprecipitation the higher molecular weight fractions of lignin likely start precipitating first, while the low molecular weight fractions tend to deposit later and thus locate on the outer shell. Capitalising this aggregation pattern, the present work presents a strategy to prepare surface-functionalised LNPs that can find applications as adhesives and alkaline stable LNPs. The entire process is based on a single-step solvent fractionation of lignin using either ethanol or ethyl acetate, subsequent functionalisation of selected fractions with epichlorohydrin, and recombination according to the original mass proportions in line with the so-called zero waste principle. Aqueous colloidal dispersions of lignins were synthesised by nanoprecipitation of epoxidised low molecular weight (MW) fractions combined with the corresponding unmodified high MW ones, and vice versa. Upon thermal treatment, LNPs containing the epoxidised insoluble fraction underwent intraparticle crosslinking, proving dimensional stability at pH 12. Conversely, LNPs including epoxidised solvent-soluble fractions resulted in interparticle crosslinking upon heating, which confirmed the surface localisation of such low MW fractions. The latter system was exploited to develop green LNP-based adhesives for aminated glass with lap shear strength outperforming prior adhesive systems based on lignin particles. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the pyrolysis products of polyhydroxyalkanoates (PHA s), polyethylene terephthalate (PET), carbon fiber reinforced composite (CFRC), and block co-polymers (PS-b-P2VP and PS-b-P4VP). The studied PHA samples were produced at temperatures of 15 and 50 oC (PHA15 and PHA50), and commercially obtained from GlasPort Bio (PHAc). Initially, PHA samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy and size exclusion chromatography (SEC) to determine the molecular weight, and structure of the polymers. Thermal techniques such as thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses were performed for PHA , CFRC , and block co-polymers to investigate the degradation temperature range and thermal stability of samples. Fast pyrolysis (500 oC, ∼102 °C s−1) experiments were conducted for all samples in a wire mesh reactor to investigate tar products and char yields. The tar compositions were investigated by gas chromatography–mass spectrometry (GC–MS), and statistical modeling was performed. The char yields of block co-polymers and PHA samples (<2 wt. %) were unequivocally less than that of the PET sample (~10.7 wt. %). All PHA compounds contained a large fraction of ethyl cyclopropane carboxylate (~ 38–58 %), whereas PAH15 and PHA50 additionally showed a large quantity of 2-butenoic acid (~8–12 %). The PHAc sample indicated the presence of considerably high amount of methyl ester (~15 %), butyl citrate (~12.9 %), and tributyl ester (~17 %). The compositional analyses of the liquid fraction of the PET and block co-polymers have shown carcinogenic and toxic properties. Pyrolysis removed matrices in the CRFC composites which is an indication of potential recovery of the original fibers. [Display omitted] • Fast pyrolysis led to the conversion of PHA into value-added liquid compounds. • Pyrolysis can potentially remove polymer matrices in the CRFC composites. • Recovered CRFC carbon fibers retained length and position in a bundle after pyrolysis. • The liquid fraction of block co-polymers comprise toxic and carcinogenic compounds. • Fast pyrolysis of PHA and block co-polymers led to char yield of < 2wt. %. [ABSTRACT FROM AUTHOR]

Advancements in fluidized bed pyrolysis mechanisms and analytical methodologies are critical for progress in the biorefinery sector in general and the aviation fuel sector in particular. The statistical modelling of pyrolysis product yields and composition allowed us to observe advantages of operating temperature and feedstock selections over the torrefaction process and catalyst addition in a fluidized bed reactor. Results suggest that the chemical composition and physical properties of bio-oil from pyrolysis of olive stones at 600°C and pinewood pellets at 500°C are the most suitable for use as fuels. This work suggests that only combined use of selected gas chromatography mass spectroscopy, UV fluorescence, nuclear magnetic resonance spectroscopy, and rheology can provide comprehensive information on pyrolysis bio-oil composition. Importantly from a technological point of view, bio-oil was characterized i) by a viscosity similar to that of fossil-based oil; ii) by a low oxygen and water content; and iii) by a balanced composition of aliphatic and aromatic species. These factors indicate that bio-oil from fluidized bed pyrolysis of biomasses is a promising material for use in the aviation industry and energy production. • A range of complementary analytical techniques can determine composition of tars. • Feedstock type and reaction temperature have a stronger impact on product yields and composition. • Addition of zeolite catalyst increased the yields of levoglucosan. • Pyrolysis of olive stones at 600 °C showed the most homogeneous biooil composition. [ABSTRACT FROM AUTHOR]

The 31 P NMR-spectroscopy-based spin trap technique involving 5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline- N -oxide (DIPPMPO) was used to achieve quantitative analyses of the radical species that are generated in different bleaching solutions. These solutions comprised a mixture of an ammonium salt and hydrogen peroxide. This spin trap-based approach was also applied, with modifications, to the study of bleaching systems of human hair. The obtained results clearly revealed the subtle differences in both the nature and the amounts of the radical species generated in different bleaching solutions, and when allowed to react on hair samples. Generally, the main species involved in the oxidation processes were superoxide and amino radicals. Their amounts, however, showed a significant variation upon the kind of bleaching system and nature of the hair, i.e. , virgin or dyed hair. [ABSTRACT FROM AUTHOR]

This paper demonstrates that the gas-filled compartments in the packing material commonly called "bubble wrap" can be repurposed in resource-limited regions as containers to store liquid samples, and to perform bioanalyses. The bubbles of bubble wrap are easily filled by injecting the samples into them using a syringe with a needle or a pipet tip, and then sealing the hole with nail hardener. The bubbles are transparent in the visible range of the spectrum, and can be used as "cuvettes" for absorbance and fluorescence measurements. The interiors of these bubbles are sterile and allow storage of samples without the need for expensive sterilization equipment. The bubbles are also permeable to gases, and can be used to culture and store micro-organisms. By incorporating carbon electrodes, these bubbles can be used as electrochemical cells. This paper demonstrates the capabilities of the bubbles by culturing E. coli, growing C. elegans, measuring glucose and hemoglobin spectrophotometrically, and measuring ferrocyanide electrochemically, all within the bubbles. [ABSTRACT FROM AUTHOR]

Over the past decade, the integration of synthetic chemistry with flow processing has resulted in a powerful platform for molecular assembly that is making an impact throughout the chemical community. Herein, we demonstrate the extension of these tools to encompass complex natural product synthesis. We have developed a number of novel flow-through processes for reactions commonly encountered in natural product synthesis programs to achieve the first total synthesis of spirodienal A and the preparation of spirangien A methyl ester. Highlights of the synthetic route include an iridium-catalyzed hydrogenation, iterative Roush crotylations, gold-catalyzed spiroketalization and a late-stage cis-selective reduction. [ABSTRACT FROM AUTHOR]

Over the past decade, the integration of synthetic chemistry with flow processing has resulted in a powerful platform for molecular assembly that is making an impact throughout the chemical community. Herein, we demonstrate the extension of these tools to encompass complex natural product synthesis. We have developed a number of novel flow-through processes for reactions commonly encountered in natural product synthesis programs to achieve the first total synthesis of spirodienal A and the preparation of spirangien A methyl ester. Highlights of the synthetic route include an iridium-catalyzed hydrogenation, iterative Roush crotylations, gold-catalyzed spiroketalization and a late-stage cis-selective reduction. [ABSTRACT FROM AUTHOR]

The fabrication and properties of 'fluoroalkylated paper' ('RF paper') by vapor-phase silanization of paper with fluoroalkyl trichlorosilanes is reported. RF paper is both hydrophobic and oleophobic: it repels water ( θappH2 O>140°), organic liquids with surface tensions as low as 28 mN m-1, aqueous solutions containing ionic and non-ionic surfactants, and complex liquids such as blood (which contains salts, surfactants, and biological material such as cells, proteins, and lipids). The propensity of the paper to resist wetting by liquids with a wide range of surface tensions correlates with the length and degree of fluorination of the organosilane (with a few exceptions in the case of methyl trichlorosilane-treated paper), and with the roughness of the paper. RF paper maintains the high permeability to gases and mechanical flexibility of the untreated paper, and can be folded into functional shapes (e.g., microtiter plates and liquid-filled gas sensors). When impregnated with a perfluorinated oil, RF paper forms a 'slippery' surface (paper slippery liquid-infused porous surface, or 'paper SLIPS') capable of repelling liquids with surface tensions as low as 15 mN m-1. The foldability of the paper SLIPS allows the fabrication of channels and flow switches to guide the transport of liquid droplets. [ABSTRACT FROM AUTHOR]

The mechanism (or mechanisms) of enthalpy- entropy (H/S) compensation in protein-ligand binding remains controversial, and there are still no predictive models (theoretical or experimental) in which hypotheses of ligand binding can be readily tested. Here we describe a particularly well-defined system of protein and ligands?human carbonic anhydrase (HCA) and a series of benzothiazole sulfonamide ligands with different patterns of fluorination?that we use to define enthalpy/entropy (H/S) compensation in this system thermodynamically and structurally. The binding affinities of these ligands (with the exception of one ligand, in which the deviation is understood) to HCA are, despite differences in fluorination pattern, indistinguishable; they nonetheless reflect significant and compensating changes in enthalpy and entropy of binding. Analysis reveals that differences in the structure and thermodynamic properties of the waters surrounding the bound ligands are an important contributor to the observed H/S compensation. These results support the hypothesis that the molecules of water filling the active site of a protein, and surrounding the ligand, are as important as the contact interactions between the protein and the ligand for biomolecular recognition, and in determining the thermodynamics of binding. [ABSTRACT FROM AUTHOR]

In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from 290 nm to 400 nm) and Ps addition and crosslinking process cause the formation of thicker nanofibers. The tensile strength and elongation at break enhancement were also determined for 13 wt.% PVA/0.5 wt.% GEL/3 wt.% Ps patch. Propolis was released quickly in the first hour and arrived at a plateau. Cell culture and contact angle results confirmed that the 3 wt.% addition of propolis reinforced mesenchymal stem cell proliferation and wettability properties of the patches. The antimicrobial activity demonstrated that propolis loaded patches had antibacterial activity against the S. aureus, but for P. aeruginosa, more studies should be performed. [ABSTRACT FROM AUTHOR]

Plant growth-promoting bacteria (PGPB) have been largely considered as beneficial in harsh and limiting environments given their effects on alleviating plant stress. For practical applications, most of the PGPB are prepared in immobilization matrices to improve the stability and benefits of bacteria. Despite the long list of immobilizing agents/carriers tested to date, a long list of desired requirements is yet to be achieved. Here, lignin stands as a scarcely tested immobilizer for bioinoculants with great potential for this purpose. The aim of this work was to demonstrate the feasibility of lignin as a carrier of the nitrogen-fixing Azospirillum brasilense. These bacteria were cultured in liquid media with recovered organosolv lignin added for bacterial immobilization. Then, lignin was recovered and the immobilized biomass was quantified gravimetrically by DNA extraction and serial dilution plating. Fluorescent microscopy as well as Congo red agar plating showed the immobilization of the bacterial cells in the lignin matrix and crystal violet dyeing showed the biofilms formation in lignin particles. A high number of cells were counted per gram of dried lignin. Lignin can be readily used as low-cost, health-safe bioinoculant carrier to be used in soil and agricultural applications. [ABSTRACT FROM AUTHOR]

Functional polymeric materials composed solely of lignin preparations appeared only very recently. A gradual paradigm shift spanning 56 years has revealed how lignin–lignin blends can upgrade the performance of 100 wt% lignin-based plastics. The view, first espoused in 1960, that lignin macromolecules are crosslinked reduces the plausibility of creating functional polymeric materials that are composed only of lignin preparations. Lignin-based materials would be much weaker mechanically if interstices remain in significant numbers between adjoining macromolecular structures that consist of rigid crosslinked chains. In 1982, random-coil features in the hydrodynamic character of kraft lignin (KL) components were evident from ultracentrifugal sedimentation equilibrium studies of their SEC behavior. In 1997, it was recognized that the macromolecular species in plastics with 85 wt% levels of KL are associated complexes rather than individual components. Finally, in 2016, the first polymeric material composed entirely of ball-milled softwood lignin (BML) was found to support a tensile strength above polyethylene. Except in its molecular weight, the BML was similar in structure to the native biopolymer. It was composed of associated lignin complexes, each with aromatic rings arranged in two domains. The inner domain maintains structural integrity largely through noncovalent interactions between cofacially-offset aromatic rings; the peripheral domain contains a higher proportion of edge-on aromatic-ring arrangements. Interdigitation between peripheral domains in adjoining complexes creates material continuity during casting. By interacting at low concentrations with the peripheral domains, non-lignin blend components can improve the tensile strengths of BML-based plastics to values well beyond those seen in polystyrene. The KL-based plastics are weaker because the peripheral domains of adjoining complexes are less capable of interdigitation than those of BML. Blending with 5 wt% 1,8-dinitroanthraquinone results in a tensile strength above that of polyethylene. Analogous effects can be achieved with 10 wt% maple γ-valerolactone (GVL) lignin which, with a structure close to the native biopolymer, imparts some native character to the peripheral domains of the KL complexes. Comparable enhancements in the behavior of BML complexes upon blending with 10 wt% ball-milled corn-stover lignin (BMCSL) result in lignin-only polymeric materials with tensile strengths well beyond polystyrene. [ABSTRACT FROM AUTHOR]

A series of ferric chloride-lignin sulfonate (FCLS) was prepared from ferric chloride and lignin sulfonate to be used as shale inhibitor. The swelling rate of clay with FCLS-2 (w/w = 0.3%) decreased to 41.9%. Compared with control, FCLS-2 displayed high inhibitive ability against the hydrating and swelling processes of clay. Thus, the swelling degree of samples with FCLS-2 was much lower than that of the control, as well as the mud ball was more stable in FCLS-2 solution. Essentially, these excellent performances in inhibitor were assigned to the hydrogen bonding, electrostatic interaction and anchoring between FCLS-2 and other components. In addition, FCLS-2 has good compatibility with other common drilling fluid additives, and it can reduce the viscosity of systems, regardless of the room temperature or high temperature. [ABSTRACT FROM AUTHOR]

Lignin, while economically and environmentally beneficial, has had limited success in use in reinforcing carbon fibers due to harmful chemicals used in biomass pretreatment along with the limited physical interactions between lignin and polyacrylonitrile (PAN) during the spinning process. The focus of this study is to use lignin obtained from chemical-free oxidative biomass pretreatment (WEx) for blending with PAN at melt spinning conditions to produce carbon fiber precursors. In this study, the dynamic rheology of blending PAN with biorefinery lignin obtained from the WEx process is investigated with the addition of 1-butyl-3-methylimidazolium chloride as a plasticizer to address the current barriers of developing PAN/lignin carbon fiber precursors in the melt-spinning process. Lignin was esterified using butyric anhydride to reduce its hydrophilicity and to enhance its interactions with PAN. The studies indicate that butyration of the lignin (BL) increased non-Newtonian behavior and decreased thermo-reversibility of blends. The slope of the Han plot was found to be around 1.47 for PAN at 150 °C and decreased with increasing lignin concentrations as well as temperature. However, these blends were found to have higher elasticity and solution yield stress (47.6 Pa at 20%wt BL and 190 °C) when compared to pure PAN (5.8 Pa at 190 °C). The results from this study are significant for understanding lignin–PAN interactions during melt spinning for lower-cost carbon fibers. [ABSTRACT FROM AUTHOR]

A new fractionation protocol for wheat straw organosolv lignin was developed on the basis of the dominating H-bonding orientations of its components. Acetone as H-bond accepting aprotic polar solvent and methanol as H-bond donating and accepting protic polar solvent were used in sequence. Obtained fractions were structurally and thermally analysed. The protocol allowed for the generation of purified lignin fractions and the isolation of a novel, yet unobserved lignin carbohydrate complex (LCC) fraction. This LCC fraction was found to contain exclusively phenyl glycosides and γ-esters as LCC motifs. [ABSTRACT FROM AUTHOR]