Nonwoven Textiles from Hyaluronan for Wound Healing Applications

Nonwoven textiles are used extensively in the field of medicine, including wound healing, but these textiles are mostly from conventional nondegradable materials, e.g., cotton or synthetic polymers such as polypropylene. Therefore, we aimed to develop nonwoven textiles from hyaluronan (HA), a biocompatible, biodegradable and nontoxic polysaccharide naturally present in the human body. For this purpose, we used a process based on wet spinning HA into a nonstationary coagulation bath combined with the wet-laid textile technology. The obtained HA nonwoven textiles are soft, flexible and paper like. Their mechanical properties, handling and hydration depend on the microscale fibre structure, which is tuneable by selected process parameters. Cell viability testing on two relevant cell lines (3T3, HaCaT) demonstrated that the textiles are not cytotoxic, while the monocyte activation test ruled out pyrogenicity. Biocompatibility, biodegradability and their high capacity for moisture absorption make HA nonwoven textiles a promising material for applications in the field of wound healing, both for topical and internal use. The beneficial effect of HA in the process of wound healing is well known and the form of a nonwoven textile should enable convenient handling and application to various types of wounds.

Transcription modulates chromatin dynamics and locus configuration sampling

In living cells the 3D structure of gene loci is dynamic, but this is not revealed by 3C and FISH experiments in fixed samples, leaving a significant gap in our understanding. To overcome these limitations we applied the "highly predictive heteromorphic polymer" (HiP-HoP) model, validated by experiments, to determine chromatin fibre mobility at the Pax6 locus in three mouse cell lines with different transcription states. While transcriptional activity minimally affects the movement of 40 kbp regions, we observed that the motion of smaller 1 kbp regions depends strongly on local disruption to chromatin fibre structure marked by H3K27 acetylation. This also significantly influenced locus configuration dynamics by modulating promoter-enhancer loops associated with protein bridging. Importantly these simulations indicate that chromatin dynamics are sufficiently fast to sample all possible conformations of loci within minutes, generating wide dynamic variability of gene loci structure within single cells. Experiments inhibiting transcription change chromatin fibre structure subtly, yet we predict they should substantially affect mobility. This combination of simulation and experimental validation provide a novel insight and mechanistic model to explain how transcriptional activity influences chromatin structure and gene dynamics.

Chemical and morphological changes in fibre structure due to material heating during ultrasonic-assisted embossing of cardboard

Embossing is a commonly used design element on printed products and packaging. It enhances the product impression with optical and haptic effects. The material deformation during the embossing of cardboard is normally done using high mechanical pressure between two dies. The use of ultrasound in the embossing process leads to a noticeable reduction of the embossing pressure and a greater embossing precision. However, there is a noticeable heating of the cardboard during the ultrasonic-assisted embossing process. This work aimed to characterise the effects of heating and to understand the reasons for the greater precision with decreased force when ultrasound is used. Therefore, the effects of the thermal ultrasonic energy on the chemical composition and the morphological properties of the fibres were investigated. The findings showed that no noticeable changes occurred in the chemical composition or fibre geometry as a result of the embossing process with ultrasound.

Analysis of deterioration characteristics in oil-immersed insulation pressboard with different durations of aging based on an image-processing method

Insulation pressboard samples were obtained by thermal aging (according to Montsinger’s formula, at 130 °C, the pressboard is heated for 0 to 32 days) and discharge experiments. SEM images of samples were analysed. Image segmentation was applied to calculate the fibre width, cross-sectional porosity, and carbon-trace area. Inter-layer fibre models were established to observe fibre morphology using 3-D reconstruction. The initial discharge voltage decreased with age, and the discharge amounts increased. After 16 days of aging, the fibre width had decreased to between 68.1% and 81.8% of unaged pressboard. As the aging increased, cellulose hydrogen bonds were broken, which affected the expansion of interlayer pores, increasing the porosity of the pressboard. After 32 days of aging, the porosity increased to 2.38 times that of a new pressboard. In addition, the longer the aging, the larger the area of carbon marks caused by the discharge breakdown. With the aggravation of thermal aging, the insulating property of pressboard decreased due to the decrease of fibre width and increase of porosity that further accelerated the damage to the fibre structure. It was concluded that the fibre width and porosity could be used as criteria to judge the degradation of pressboard.

The structure of dislocations in hemp (Cannabis sativa L.) fibres and implications for mechanical behaviour

Elementary fibres isolated from mechanically processed technical hemp were axially sectioned and imaged with transmission electron microscopy (TEM) to reveal details of the axial morphology of dislocations in the fibre. The overall aim was to investigate the detailed axial structural changes that the fibres undergo during processing, to help better understand the alterations in the deformation behaviour the fibres undergo following processing. The images showed the structure and morphology of dislocations as well as the different forms of damage that processing produced in the fibre structure, such as misalignment of the microfibrils, delamination, and buckled cellulose microfibrils. Furthermore, the results of this work show the ability that axial sectioning of the fibre has to reveal new details of the cell wall structure of hemp to offer new insights in the study of the fibre structure. In turn, the results of this work may help explain the mechanical behaviour of the fibres when they are loaded, as well as help explain the greater chemical accessibility of dislocations, for example, when the fibre is acid hydrolysed.