Clinical work and research on diabetic wound repair remain challenging globally. Although various conventional wound dressings have been continuously developed, the efficacy is unsatisfactory. The effect of drug delivery is limited by the depth of penetration. The sustained release of biomolecules from biological wound dressings is a promising treatment approach to wound healing. An assortment of cell-derived exosomes (exos) have been proved to be instrumental in tissue regeneration, and researchers are dedicated to developing biomolecules carriers with unique properties. Herein, we reported a methacrylate gelatin (GelMA) microneedles (MNs) patch to achieve transdermal and controlled release of exos and tazarotene. Our MNs patch comprising GelMA/PEGDA hydrogel has distinctive biological features that maintain the biological activity of exos and drugs in vitro. Additionally, its unique physical structure prevents it from being tightly attached to the skin of the wound, it promotes cell migration, angiogenesis by slowly releasing exos and tazarotene in the deep layer of the skin. The full-thickness cutaneous wound on a diabetic mouse model was carried out to demonstrate the therapeutic effects of GelMA/PEGDA@T + exos MNs patch. As a result, our GelMA/PEGDA@T + exos MNs patch presents a potentially valuable method for repairing diabetic wound in clinical applications. Graphic Abstract

Soil–rock mixtures, which are very complicated inhomogeneous materials, are widely encountered in geotechnical engineering projects. In this paper, in situ tests were performed on six samples of soil–rock mixtures in the Hutiao Gorge reservoir area to examine their mechanical characteristics. The deformation of the mixtures is closely related to the weight proportion of rock fragments and their size distribution, indicating that there may be critical fragment sizes that influence their mechanical properties, particularly cohesion. The soil–rock mixtures are sensitive to water. The results of the comparison between the tests of natural soil–rock mixtures and simulated-rain soil–rock mixtures give useful measured data for engineering evaluation and design. For natural soil–rock mixtures the cohesion c was 1·53 kPa and the internal friction angle ϕ was 46·0°; for saturated soil–rock mixtures c was 0·30 kPa and ϕ was 59·2°.

According to the observational data of viscous debris flows with hyper-concentration, debris flows can be classified into three types: high-viscous, viscous, and sub-viscous debris flows. Distinct formation mechanism of different graded bedding structures in deposits of viscous debris flows was analyzed in this paper by using their yield-stress ratio and flow plug ratio. This paper specially analyzed the effect of Weissenberg which the gravels in squirm condition of hyper-concentration viscous flows would tend to move vertically, and the formation mechanism of the gravels accumulated at surface was also studied. The analysis in this paper can establish a foundation for the studies on differentiation of bedding structures of debris flow deposits and studies on dynamic parameters of debris flows.