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Developing stable and reusable biocatalysts is crucial for improving the sustainability of industrial processes, including enzymatic deinking. In this article, cellulase is immobilized onto chitosan-polyvinyl alcohol (Cs/PVA/Ga) biopolymer beads using glutaraldehyde cross-linking, creating a durable and recyclable catalytic system. Scanning electron microscopy revealed a bead-like structure, and fourier transform infrared spectroscopy spectra confirmed successful enzyme incorporation without compromising the polymer's integrity. Immobilization shifted the optimal activity of cellulase from pH 5 to pH 8 and raised the temperature optimum from 50 °C to between 60 and 70 °C, indicating improved catalytic stability. Kinetic studies showed a decrease in Km from 0.75 mM for the free enzyme to 0.4mM for the immobilized form, suggesting increased substrate affinity. Thermal stability tests revealed cellulase@Cs/PVA/Ga maintained over 83% of its activity at 80 °C for 60 min, compared to only 50% for the free enzyme. The immobilized cellulase demonstrated 90% activity retention after seven reuse cycles. Biodeinking experiments with recycled pulp evidenced optimal cellulose and hemicellulose retention with a 5% enzyme dosage, while effluent analysis showed enhanced removal of ink residues with the immobilized enzyme, highlighting the ecoefficient potential of this approach for sustainable paper recycling.

Many biomolecular studies start with labeling a protein with a fluorescent label, spin label, or chemical label. The methanethiosulfonate (mts)-linking group suffers from a hitherto not-understood side reaction that leads to label-dimerization instead of the desired linking of the label to the cysteine of the protein. Using electron paramagnetic resonance and mass spectrometry, the side reaction is studied for the MTSL ((1-oxyl-2,2,5,5-tetramethyl-Δ-3-pyrroline-3-methyl) methanethiosulfonate) and the (1-oxyl-2,2,5,5-tetramethylpyrrolidin-3-yl) methyl methanethiosulfonate label. At 0.1 mM MTSL, substantial dimer formation is observed within the first 5 h. The reaction pathway is elucidated and the structure of the disulfide-linked asymmetric dimer is suggested. The reaction seems not to involve the nitroxide or a radical reaction, suggesting that this reaction could also occur for other mts-linked functional or labeling groups.

This study presents an innovative heterogeneous nanocatalytic system designed through a multistep synthetic approach involving the surface functionalization of perlite nanoparticles (Perlite NPs/Met-Co(II)). Comprehensive characterization using fourier transform infrared spectroscopy (FTIR), X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray analysis (EDX), elemental mapping, thermogravimetric analysis, and brunauer-emmett-teller (BET) analyses confirms the successful formation of a hierarchically structured catalyst. The catalyst enables efficient one-pot multicomponent synthesis of pyrazolopyranopyrimidines in water (100 °C, 5 mg loading), yielding 87–95% in 30–60 min. The presented method adhering to green principles and also recyclability (6 cycles) and synergistic performance provides an atom-economic platform for sustainable heterocycle synthesis.

The modification of well-known β-peptide helices has been achieved by the application of N-terminal betaine conjugation. The 3D self-organization of oligomers formed by [1S,2S]-2-aminocyclopentanecarboxylic acid (ACPC), [1R,2R]-2-aminocyclohexanecarboxylic acid (ACHC), and an alternating heterochiral homooligomer of [1S,2S]-ACPC and [1R,2R]-ACPC was studied. Results of NMR, ECD, FT-IR, and molecular modeling showed that for [1S,2S]-ACPC pentamer (1), the betaine conjugation did not affect the folding to an H12 helix. In contrast, for the [1R,2R]-ACHC tetramer (2) betaine conjugation notably influenced the folding, and an H14 helix was observed instead of the expected H10 helix. In addition, this is the first observation of self-association for an H12 helix forming β-peptide. Based on TEM images, this association leads to vesicle morphologies. For the alternating heterochiral homooligomer [1S,2S]-ACPC and the [1R,2R]-ACPC pentamer (3), betaine conjugation enhances the solubility of the system. Moreover, the formation of an expected E-strand can be anticipated, since self-association was found in the form of a fibrin net-like structure in TEM images. Betaine conjugates described herein open a new area of bioactive peptide foldamer construction, since the introduced quaternary charges may lead to important receptor-ligand interactions, while potential material science applications can also be realized.

Tungsten (VI) hexachloride, WCl₆, and tungsten (VI) oxytetrachloride, WOCl₄, are of interest in a variety of technological applications. In the present work, complete vibrational assignments are provided for both molecules in the “free” state (i.e., in the gas phase or in solution) and in the solid state. The first inelastic neutron scattering spectra of both molecules in the solid state are recorded. The assignments are supported by density functional theory calculations. In all cases, the W–Cl stretching modes occur in the 300–400 cm⁻¹ range, and the Cl–W–Cl bending modes in the 100-250 cm⁻¹ range.

A combined Electrospray Infrared MultiPhoton Dissociation Mass Spectrometry (ESI-IRMPD-MS) and Density Functional Theory (DFT) investigation has allowed to elucidate the structural features of the species arising from the triple dehydration of D-fructose in the gas phase. The experimental workflow involves measuring and comparing the IRMPD spectra of different ionic populations: protonated 5-hydroxymethylfurfural [HMF·H]⁺ and the ionic species coming from the triple dehydration of the ammonium-D–fructose complex ([Fru·NH₄]⁺). The IR-photon induced fragmentation of [Fru·NH₄]⁺ reveals the coexistence of two ionic populations, which arise from of two independent not intercrossing fragmentation pathways of the ionic precursor. One population exhibits an IRMPD spectrum matching with the ([HMF·H]⁺) one and corresponding to a carbonyl-protonated structure. The second ionic product is its C2-protonated protomer, which lies 75 kJ/mol above the global minimum. The presence of a less stable protomer is most likely due to its gas-phase kinetic trapping. These findings contribute to a more refined understanding of gas-phase carbohydrate dehydration and isomer formation at the molecular level.

Heterogeneous catalytic selective hydrogenation (HCSH) of vegetable oils is a reactive pathway to maximize the fraction of monounsaturated oleic acid, a component of industrial interest, thanks to its stability and low-temperature properties. Kinetics of HCSH is usually interpreted by pseudo-first order laws, as previously done by this research group with data from batch tests on canola oil (Lindlar catalyst, 120–180 °C, 0.4–1.2 MPa): the pseudo-first order kinetics could interpret the observed phenomenon only by variable selectivities (i.e., ratios of kinetic constants). The present work proposes a refined modeling by Hougen–Watson approach. Detailed reaction mechanisms were hypothesized, challenging the following alternatives: (i) H₂ adsorption on the catalyst occured (Hinshelwood–Langmuir) or not (Eley–Rideal), (ii) H₂ adsorption was molecular or dissociative, (iii) H₂ adsorption was competitive or not with fatty acids adsorption, and (iv) reaction intermediates were formed or not. Six reaction mechanisms were developed with related kinetic rate laws for HCSH. Their kinetic parameters were regressed for the abovementioned experimental data by a purposely developed MATLAB script. The best mechanism was chosen based on the highest explained variance ($$) and the lowest number of parameters. Chemical–physical meaningfulness of regressed parameters for the best model was checked by comparison with the literature.

pH-sensitive ion-selective field effect transistors (ISFETs) are commercially available nowadays, offering high robustness, resolution, accuracy, and durability. A crucial drawback is their high price and permanent power demand. Incorporating commercially available small-sized ISFET sensors into battery-powered devices requires a thorough evaluation and the development of strategies to reduce power consumption. In this work, a direct comparison of three different commercial ISFETs is presented using a newly developed evaluation process that aims to investigate long-term performance. The different behaviors in conditioning, linearity, accuracy, response times, and long-term stability in detail are discussed. Furthermore, strategies to decrease power consumption are presented by adjusting the operating conditions and introducing an OnOff-protocol. It is found that all ISFETs have limitations in their overall performance with the best performers being 1) Winsense, with the highest slope of 59.7 mV pH⁻¹; 2) Microsens, with the highest potential output precision under the recommended working point conditions (±0.01−0.03 pH) with SD and reduced working conditions (± 0.01 pH) with WD; and 3) Sentron, with the highest stability under both power-reducing strategies. With the combination of both power-reducing strategies, the ISFET's power demand is reduced by 98.8%.

Formic acid is obtained as a byproduct of biomass pyrolysis and is used as a liquid organic hydrogen carrier due to its low decomposition temperature, enabling hydrogen production under mild conditions with noble metals. The decomposition of FA in the vapor phase using different rhenium phases (metal, carbide, and oxide) supported on graphite and carbon nanotubes was studied within a temperature range of 80–220 °C, in a fixed-bed reactor with a space velocity of 651 mL g_cat h⁻¹. The catalysts were characterized by N₂ adsorption–desorption, H₂-temperature-programmed reduction, transmission electron microscopy, temperature programmed desorption-ammonia, temperature programmed reaction-methanol, X-ray diffraction, and X-ray photoelectron spectroscopy. Graphite-supported catalysts achieved higher activity than carbon nanotube-supported ones, due to the higher rhenium dispersion on graphite. Catalytic reactions revealed that ReC/G exhibited superior performance at lower temperatures per active site, attributed to the rhenium carbide phase. High selectivity toward CO₂ was observed across all catalysts, except for ReOx/G at lower temperatures, where differences in active site characteristics likely influenced performance. ReC/G displayed the highest intrinsic activity, highlighting rhenium carbide as a more active phase than metallic or oxide rhenium.

A systematic investigation of the catalyst-free Strecker reaction is conducted in aqueous buffer, offering an efficient and green alternative that leads to α-aminonitriles without the need of chromatography. Optimization reveals that low pH and high buffer concentration significantly enhance conversion, with yields up to 97%. Broad substrate scope is demonstrated with various aldehydes, ketones, and amines, leading to key intermediates for natural and unnatural amino acids. Potassium cyanide and acetone cyanohydrin are established, latter as a safer and effective cyanide source, and reactions are conducted also in buffer–methyl tert-butyl ether mixed solvent further improving the methodology. It is hypothesized that, based on the similarity to cyanohydrin formation, the hydroxynitrile lyases (HNLs) might transform imines to aminonitriles. Adding AtHNL and HbHNL further accelerates the reaction suggesting an undiscovered reactivity of these enzymes.