Molecular Dynamics Simulations of Cellulose and Dialcohol Cellulose under Dry and Moist Conditions.

The development of wood-based thermoplastic polymers that can replace synthetic plastics is of high environmental importance, and previous studies have indicated that cellulose-rich fiber containing dialcohol cellulose (ring-opened cellulose) is a very promising candidate material. In this study, molecular dynamics simulations, complemented with experiments, were used to investigate how and why the degree of ring opening influences the properties of dialcohol cellulose, and how temperature and presence of water affect the material properties. Mechanical tensile properties, diffusion/mobility-related properties, densities, glass-transition temperatures, potential energies, hydrogen bonds, and free volumes were simulated for amorphous cellulosic materials with 0-100% ring opening, at ambient and high (150 °C) temperatures, with and without water. The simulations showed that the impact of ring openings, with respect to providing molecular mobility, was higher at high temperatures. This was also observed experimentally. Hence, the ring opening had the strongest beneficial effect on "processability" (reduced stiffness and strength) above the glass-transition temperature and in wet conditions. It also had the effect of lowering the glass-transition temperature. The results here showed that molecular dynamics is a valuable tool in the development of wood-based materials with optimal thermoplastic properties.

Experimental and simulated distribution and interaction of water in cellulose esters with alkyl chain substitutions.

This study investigated the effect of the average length of substituted side chains in different cellulose esters on water sorption and the water association mechanism. For this purpose, a set of esters with a similar total degree of substitution was selected: cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate. Dynamic vapor sorption was used to determine the effect of the side chain length on sorption, desorption, and the occurrence of water clustering. Since water association in the structure was of interest, molecular dynamics simulations were performed on cellulose acetate and cellulose acetate propionate. This study showed that cellulose acetate appears to be water-sensitive and experiences hysteresis upon water sorption, which was attributed to structural changes. The simulations also showed that water is screened out by the side chains and forms intermolecular hydrogen bonds, primarily to the carbonyl oxygen rather than the residual hydroxyl groups.

Gambling operators' social media image creation in Finland and Sweden 2017-2020.

Aim: This is a first audit of how gambling operators in Finland and Sweden address citizens on social media. The study is able to pinpoint some differences between how gambling operators utilise social media in a state monopoly system (Finland) and in a license-based regulatory framework (Sweden). Methods: Curated social media posts from Finland- and Sweden-based accounts in national languages were collected from March 2017, 2018, 2019 and 2020. The data (N = 13,241) consist of posts published on YouTube, Twitter, Facebook, and Instagram. The posts were audited in terms of frequency of posting, content and user engagement. Results/Conclusions: Operators in both countries were, in general, active on their social media accounts, but there was a decline in number of posts between 2017 and 2020. A substantial number of the analysed posts did not visually portray gambling or games. In the Swedish license system, operators seem to present themselves more straightforwardly as gambling companies, whereas in the Finnish monopoly system the image was more tied to a social role of public good doing. Beneficiaries of gambling revenues became less visible in the Finnish data over time.

Mass Transport of Lignin in Confined Pores.

A crucial step in the chemical delignification of wood is the transport of lignin fragments into free liquor; this step is believed to be the rate-limiting step. This study has investigated the diffusion of kraft lignin molecules through model cellulose membranes of various pore sizes (1-200 nm) by diffusion cells, where the lignin molecules diffuse from donor to acceptor cells through a membrane, where diffusion rate increases by pore size. UV-vis spectra of the donor solutions showed greater absorbance at higher wavelengths (~450 nm), which was probably induced by scattering due to presence of large molecules/clusters, while acceptor samples passed through small pore membranes did not. The UV-vis spectra of acceptor solutions show a characteristic peak at around 350 nm, which corresponds to ionized conjugated molecules: indicating that a chemical fractionation has occurred. Size exclusion chromatography (SEC) showed a difference in the molecular weight (Mw) distribution between lignin from the donor and acceptor chambers. The results show that small pore sizes enable the diffusion of small individual molecules and hinder the transport of large lignin molecules or possible lignin clusters. This study provides more detail in understanding the mass transfer events of pulping processes.

Screening of hydrogen bonds in modified cellulose acetates with alkyl chain substitutions.

This study aimed to elucidate how the glass transition temperature and water interactions in cellulose esters are affected by the structures of their side chains. Cellulose acetate, cellulose acetate propionate and cellulose acetate butyrate with three fractions of butyrates, all having the same total degree of substitution, were selected, and hot-melt pressed. The degree of substitution, structural properties, and water interactions were determined. The Hansen solubility parameters were calculated and showed that the dispersive energy dominates the total cohesive energy, followed by hydrogen bonding and polar energy. The glass transition temperature (Tg) decreased, counter-intuitively, with an increased total cohesive energy, which can be explained by the short-range hydrogen bonds being screened by the increased length of the substituents. The solubility and penetration of water in the cellulose esters decreased with increased side chain length, although the hydrogen bonding energies for all the esters were approximately constant.

Influence of Drug Load on the Printability and Solid-State Properties of 3D-Printed Naproxen-Based Amorphous Solid Dispersion.

Fused deposition modelling-based 3D printing of pharmaceutical products is facing challenges like brittleness and printability of the drug-loaded hot-melt extruded filament feedstock and stabilization of the solid-state form of the drug in the final product. The aim of this study was to investigate the influence of the drug load on printability and physical stability. The poor glass former naproxen (NAP) was hot-melt extruded with Kollidon® VA 64 at 10-30% w/w drug load. The extrudates (filaments) were characterised using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). It was confirmed that an amorphous solid dispersion was formed. A temperature profile was developed based on the results from TGA, DSC, and DMA and temperatures used for 3D printing were selected from the profile. The 3D-printed tablets were characterised using DSC, X-ray computer microtomography (XµCT), and X-ray powder diffraction (XRPD). From the DSC and XRPD analysis, it was found that the drug in the 3D-printed tablets (20 and 30% NAP) was amorphous and remained amorphous after 23 weeks of storage (room temperature (RT), 37% relative humidity (RH)). This shows that adjusting the drug ratio can modulate the brittleness and improve printability without compromising the physical stability of the amorphous solid dispersion.