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Combining spatially localized X-ray diffraction (XRD) with X-ray microtomography (XMT) enables the mapping of the micro- and nanoscale structures simultaneously. The combination of these methods results in a powerful tool when considering the structural studies of hierarchical materials, allowing one to couple the relationships and connections of the structures at various scales. In this study, XMT was used to map the anatomy and cellular structures in 3D in tension and opposite wood with 1.5 µm resolution, while XRD was used to determine the cellulose crystallite widths and microfibril orientations with 100 µm spatial resolution within the same tissues. Tension wood (TW) has an important biological function with clearly distinct properties to opposite (OW) and normal wood, e.g. differing cellular structures with a higher cellulose content. This is the first study of very young hybrid aspen saplings (1-month-old) using the combined diffraction tomography method. The TW tissues could be identified from the OW tissues based on both the XMT and XRD results: TW had a higher average size of the cellulose crystallites and smaller mean microfibril angles (mMFA) than those in OW. With the XRD data, we were able to reconstruct the images of the cross sections of the saplings using the structural parameters (cellulose crystallite width and mMFA) as contrast mechanisms. As far as the authors know, there are no previous studies with images on any TW samples using the XRD-based contrast. Home laboratory bench-top set-up offers its advantages for these studies, considering the number of samples characterized, time-dependent studies and larger field of views.

Publisher Copyright: © 2022 Walter de Gruyter GmbH, Berlin/Boston 2022. Paper-grade pulp, rich in hemicellulose content, is a cheap source for producing dissolving pulps. The main challenge in the conversion of a cheap paper-grade pulp to a higher-valued dissolving pulp is the selective removal of hemicelluloses, while maintaining the pulp reactivity. This paper presents a comparison of different hemicellulose extraction methods such as cold caustic extraction, IONCELL-P(ulp) and xylanase treatment on converting fully bleached soda bagasse paper-grade pulp to dissolving pulp. IONCELL-P(ulp) treatment, using an optimized1-ethyl-3-methylimidazolium acetate/water as the extraction medium, yielded 85% xylan removal, which is comparable to the cold caustic extraction or a combination of xylanase treatment and cold caustic extraction. A complete separation of the two polymers by IONCELL-P(ulp) is not possible due to the overlap of the molecular masses of the cellulose and xylan molecules, an inherent characteristic of sugarcane bagasse pulp. All the investigated methods effectively removed xylan, with differences in the selectivity and the reactivity of the remaining pulp.

Stinging nettle (Urtica dioica) is a potential source material for industrial applications. However, systematic research on the ultrastructural properties of nettle fibres is lacking. Determining the ultrastructure of nettle and the other bast fibres also provides new insights into the studies of archaeological fibres and their usage. In this study, the nanostructure of modern and ancient nettle samples was studied using wide-angle X-ray scattering (WAXS) and compared to other bast fibres. The culturo-historical fibre samples consisted of nettle, flax, and hemp from White Karelian textiles collected 1894 as well as of 800–900-year-old archaeological textile fragments from Ravattula Ristimäki burial site, Finland. Using WAXS, the average cellulose crystallite widths, relative crystallinities and orientational order (including microfibril angle for the modern fibres) were determined and compared. The results also revealed the suitability of the WAXS analysis for fibre identification. The crystallite widths were of the similar size for all modern fibres (3.4–4.8 nm). Subtle differences in the relative crystallinities in descending order (from flax to nettle, and finally hemp) were observed. Also, subtle differences in the mean MFAs were observed (10 ± 1° for flax, 12 ± 1° for nettle, and 14 ± 1° for hemp). For the culturo-historical fibres, the values for crystallite widths and relative crystallinities were larger compared to the corresponding modern references. In addition, features due to the presence of non-cellulosic, crystalline substances (e.g., calcium oxalates) were detected in the WAXS patterns of all the modern nettle fibres. These features could potentially be used as a tool for identification purposes. Graphical abstract

The diversity and safety of nanofibrillated cellulose (NFC) hydrogels have gained a vast amount of interest at the pharmaceutical site in recent years. Moreover, this biomaterial has a high potential to be utilized as a protective matrix during the freeze-drying of heat-sensitive pharmaceuticals and biologics to increase their properties for long-term storing at room temperature and transportation. Since freeze-drying and subsequent reconstitution have not been optimized for this biomaterial, we must find a wider understanding of the process itself as well as the molecular level interactions between the NFC hydrogel and the most suitable lyoprotectants. Herein we optimized the reconstitution of the freeze-dried NFC hydrogel by considering critical quality attributes required to ensure the success of the process and gained insights of the obtained experimental data by simulating the effects of the used lyoprotectants on water and NFC. We discovered the correlation between the measured characteristics and molecular dynamics simulations and obtained successful freeze-drying and subsequent reconstitution of NFC hydrogel with the presence of 300 mM of sucrose. These findings demonstrated the possibility of using the simulations together with the experimental measurements to obtain a more comprehensive way to design a successful freeze-drying process, which could be utilized in future pharmaceutical applications.

The structure of hardwoods representing eight tropical and five temperate species was characterized from the atomistic level up to the cellular level using X-ray scattering, X-ray microtomography and light microscopy. The species were chosen for this study based on their popularity as tonewoods. The ultrastructure of wood cell walls, including crystallite size, orientation and close-range order of cellulose microfibrils were determined by small- and wide-angle X-ray scattering (SAXS, WAXS). The SAXS patterns were interpreted by using an analytical model of cylinders packed in a hexagonal close-range order with paracrystalline distortion. The values for the cylinder diameters given by this model were compared to the average crystallite widths obtained by WAXS using the Scherrer equation. In six out of 26 samples, all of these representing tropical species used especially in fretboard parts of electric guitars, large differences between these two sizes were obtained. The WAXS and microscopy results of these samples corresponded to tension wood structures. These comparisons and interpretations of SAXS results have not been previously presented for any tropical hardwoods, especially related to those containing tension wood tissue. The importance of the ultrastructural characterization was highlighted in this study in the case of tropical hardwood samples.

HCl gas hydrolysis of a bacterial cellulose (BC) aerogel followed by 2,2,6,6-tetramethylpiperidine-1-oxyl radical-mediated oxidation was used to produce hydrolyzed BC with carboxylate groups, which subsequently disintegrated into a stable dispersion of cellulose nanocrystals (CNCs). The degree of polymerization was successfully reduced from 2160 to 220 with a CNC yield of >80%.

Efficient, abundant and low-cost catalysts for the oxygen evolution reaction (OER) are required for energy conversion and storage. In this study, a doping-etching route has been developed to access defect rich Fe-Co-Al (Fe-Co-Al-AE) ternary hydroxide nanosheets for superior electrochemical oxygen evolution. After partial etching of Al, ultrathin Fe3Co2Al2-AE electrocatalysts with a rich pore structure are obtained with a shift of the cobalt valence state towards higher valence (Co2+-> Co3+), along with a substantial improvement in the catalytic performance. Fe3Co2Al2-AE shows a notably lower overpotential of only 284 mV at a current density of 10 mA cm(-2) and double the OER mass activity of the etching-free Fe3Co2Al2 with an overpotential of 350 mV. Density functional theory shows the leaching of Al changes the rate-determining step of the OER from conversion of *OOH into O-2 on Fe3Co2Al2 to formation of OOH from *O on the Al-defective catalysts. This work demonstrates an effective route to design and synthesize transition metal electrocatalysts and provides a promising alternative for the further development of oxygen evolution catalysts.

Cellulose hydrolysis is an extensively studied process due to its relevance in the fields of biofuels, chemicals production, and renewable nanomaterials. However, the direct visualization of the process accompanied with detailed scaling has not been reported because of the vast morphological alterations occurring in cellulosic fibers in typical heterogeneous (solid/liquid) hydrolytic systems. Here, we overcome this distraction by exposing hardwood cellulose nanofibers (CNFs) deposited on silica substrates to pressurized HCl gas in a solid/gas system and examine the changes in individual CNFs by atomic force microscopy (AFM). The results revealed that hydrolysis proceeds via an intermediate semi-fibrous stage before objects reminiscent of cellulose nanocrystals were formed. The length of the nanocrystal-like objects correlated well with molar mass, as analyzed by gel permeation chromatography, performed on CNF aerogels hydrolyzed under identical conditions. Meanwhile, X-ray diffraction showed a slight increasein crystallinity index as the hydrolysis proceeded. The results provide a modern visual complement to >100 years of research in cellulose degradation.