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Deep partial thickness burn wounds present big challenges due to the long healing time, large size and irregular shape, pain and reinjury at wound dressing changes, as well as scarring. The clinically effective therapy to alleviate pain at wound dressing changes, and the scar left on the skin after the healing of wound is still unavailable. To combat this, we develop a nanocomposite self-healing hydrogel that can be injected into irregular and deep burn wound beds and subsequently rapidly self-heal to reform into an integrated piece of hydrogel that thoroughly fills the wound area and protects the wound site from external environment, finally being painlessly removed by on-demand dissolving using amino acid solution at wound dressing changes, which accelerates deep partial thickness burn wound healing and prevents scarring. The hydrogel is made out of naturally occurring polymers, namely, water-soluble carboxymethyl chitosan (CMC) and rigid rod-like dialdehyde-modified cellulose nanocrystal (DACNC). They are cross-linked by dynamic Schiff-base linkages between amines from CMC and aldehydes from DACNC. The large aspect ratio and specific surface area of DACNC raise massive active junctions within the hydrogel, which can be readily broken and reformed, allowing hydrogel to rapidly self-heal. Moreover, DACNC serves as nanoreinforcing fillers to improve the hydrogel strength, which also restricts the “soft” CMC chains’ motion when soaked in aqueous system, endowing high fluid uptake capacity (350%) to hydrogel while maintaining integrity. Cytotoxicity assay and three-dimensional cell culture demonstrate excellent biocompatibility of the hydrogel and capacity as extracellular matrix to support cell growth. This work opens a novel pathway to fabricate on-demand dissolvable self-healing hydrogels to speed deep partial thickness burn wound healing and eliminate pain at wound dressing changes and prevent scar formation.

Human observer performance on a 2AFC lesion detection task in CT with a uniform background can be accurately predicted by a CHO model observer at different radiation dose levels and for both FBP and IR methods.

Gnetophytes are an enigmatic gymnosperm lineage comprising three genera, Gnetum, Welwitschia and Ephedra, which are morphologically distinct from all other seed plants. Their distinctiveness has triggered much debate as to their origin, evolution and phylogenetic placement among seed plants. To increase our understanding of the evolution of gnetophytes, and their relation to other seed plants, we report here a high-quality draft genome sequence for Gnetum montanum, the first for any gnetophyte. By using a novel genome assembly strategy to deal with high levels of heterozygosity, we assembled >4 Gb of sequence encoding 27,491 protein-coding genes. Comparative analysis of the G. montanum genome with other gymnosperm genomes unveiled some remarkable and distinctive genomic features, such as a diverse assemblage of retrotransposons with evidence for elevated frequencies of elimination rather than accumulation, considerable differences in intron architecture, including both length distribution and proportions of (retro) transposon elements, and distinctive patterns of proliferation of functional protein domains. Furthermore, a few gene families showed Gnetum-specific copy number expansions (for example, cellulose synthase) or contractions (for example, Late Embryogenesis Abundant protein), which could be connected with Gnetum's distinctive morphological innovations associated with their adaptation to warm, mesic environments. Overall, the G. montanum genome enables a better resolution of ancestral genomic features within seed plants, and the identification of genomic characters that distinguish Gnetum from other gymnosperms. NATuRe PLANTS ArticlesNATurE PLANTs phylogenetic position of gnetophytes, with topologies differing depending on the type of sequence data (for example, plastid versus nuclear genes, nucleotide versus amino acid data) and analytical approach used (for example, maximum parsimony, maximum likelihood, Bayesian, multispecies coalescent based methods) [6][7][8] . Consequently, several possible hypotheses have been put forward that place gnetophytes as sister to (1) Pinaceae ('Gnepine' hypothesis); (2) cupressophytes ('Gnecup' hypothesis); (3) all conifers ('Gnetifer' hypothesis); (4) all other gymnosperms; or (5) all seed plants 9 . Currently, the emerging consensus, based on both older and more recent studies, and recently released data from the 1KP initiative (see https://sites.google.com/a/ualberta.ca/onekp/, and Wickett et al. 8 ), indicates that gnetophytes are sister to, or within, the conifers.So far, the availability of whole genome sequences for gymnosperms has been limited to conifers (specifically to Pinaceae) [10][11][12][13] and G. biloba 14 , with no whole genome assemblies available for the two remaining major seed plant lineages-cycads and gnetophytes. This deficiency, together with the conflicting phylogenetic evidence for relationships among these groups, is impeding our understanding of genome evolution across all seed plants. Here, we present a high-quality draft genome of Gnetum ...

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Benzaldehyde-terminated telechelic four-armed polyethylene glycol (PEG-BA) is synthesized and cross-linked with carboxymethyl chitosan (CMC) to form dynamic hydrogels with strong mechanical performance. The gelation temperature and time, mechanical performance, and self-healing behaviors are systematically investigated. The hydrogels have good storage modulus up to 3162.06 ± 21.06 Pa, comparable to conventional bulk hydrogels. The separated alternate hydrogel lines connect together to become an integrated hydrogel film after 5 min at room temperature without any external intervention. This is due to the dynamic equilibrium between the Schiff base linkages and the aldehyde groups of PEG-BA and amine groups on CMC backbone. The hydrogel shows excellent cytocompatibility and the cell viability is as high as 90.7 ± 6.8% after 2 d 3D encapsulation in the hydrogel. In vivo tests indicate that the hydrogels can effectively stop bleeding when the hydrogel is directly injected into a rabbit liver incision. The total blood loss is reduced from 0.65 ± 0.10 g to 0.29 ± 0.11 g, and the hemostasis time is decreased from 167 ± 21 s to 120 ± 10 s, when compared to a gauze treatment with physical compression. These self-healing hydrogels have potential to be used as a novel hemostatic material.

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