Highly efficient dissolution and reinforcement mechanism of robust and transparent cellulose films for smart packaging.

The packaging of fresh foods increasingly focuses on renewable and eco-friendly cellulose films, but their low dissolution efficiency and weak mechanical strength greatly limit their wide application, which also cannot be used for smart packaging. Here, a highly efficient synergistic chloride-salt dissolution method was proposed to fabricate robust, transparent, and smart cellulose films. Cellulose films with appropriate Ca2+ concentration exhibited robust mechanical strength, better thermal stability, high transparency and crystallinity. The metal chelation of Ca2+ with cellulose chains could induce cellulose chain arrangement during the cellulose regeneration process. Particularly, compared to pure cellulose films, the tensile strength and elongation at break of cellulose films with suitable Ca2+ were increased by 167 % and 200 %, respectively. Moreover, optimal cellulose films can be used to reflect the quality of the fruit by detecting changes in ethanol gas. Hence, a novel strategy is presented to fabricate robust and transparent cellulose films with great potential application for smart packaging.

Tailoring Hydronium ion Driven Dissociation-Chemical Cross-Linking for Superfast One-Pot Cellulose Dissolution and Derivatization to Build Robust Cellulose Films.

Concepts of sustainability must be developed to overcome the increasing environmental hazards caused by fossil resources. Cellulose derivatives with excellent properties are promising biobased alternatives for petroleum-derived materials. However, a one-pot route to achieve cellulose dissolution and derivatization is very challenging, requiring harsh conditions, high energy consumption, and complex solubilizing. Herein, we design a one-pot tailoring hydronium ion driven dissociation-chemical cross-linking strategy to achieve superfast cellulose dissolution and derivatization for orderly robust cellulose films. In this strategy, there is a powerful driving force from organic acid with a pKa below 3.75 to dissociate H+ and trigger the dissolution and derivatization of cellulose under the addition of H2SO4. Nevertheless, the driving force can only trigger a partial swelling of cellulose but without dissolution when the pKa of organic acid is above 4.26 for the dissociation of H+ is inhibited by the addition of inorganic acid. The cellulose film has high transmittance (up to ∼90%), excellent tensile strength (∼122 MPa), and is superior to commercial PE film. Moreover, the tensile strength is increased by 400% compared to cellulose film prepared by the ZnCl2 solvent. This work provides an efficient solvent, which is of great significance for emerging cellulose materials from renewable materials.

Next-generation self-adhesive dressings: Highly stretchable, antibacterial, and UV-shielding properties enabled by tannic acid-coated cellulose nanocrystals.

Hydrogels with excellent high-water uptake and flexibility have great potential for wound dressing. However, pure hydrogels without fiber skeleton faced poor water retention, weak fatigue resistance, and mechanical strength to hinder the development of the dressing as next-generation functional dressings. We prepared an ultrafast gelation (6 s) Fe3+/TA-CNC hydrogel (CTFG hydrogel) based on a self-catalytic system and bilayer self-assembled composites. The CTFG hydrogel has excellent flexibility (800% of strain), fatigue resistance (support 60% compression cycles), antibacterial, and self-adhesive properties (no residue or allergy after peeling off the skin). CTFG@S bilayer composites were formed after electrospun silk fibroin (SF) membranes were prepared and adhesive with CTFG hydrogels. The CTFG@S bilayer composites had significant UV-shielding (99.95%), tensile strain (210.9 KPa), and sensitive humidity-sensing properties. Moreover, the integrated structure improved the mechanical properties of electrospun SF membranes. This study would provide a promising strategy for rapidly preparing multifunctional hydrogels for wound dressing.

Value of susceptibility-weighted imaging in differentiating benign from malignant portal vein thrombosis.

Background: Many diseases are accompanied by portal vein thrombosis (PVT), and its nature is closely related to its prognosis and treatment. It is important to evaluate magnetic resonance imaging (MRI) parameters, including susceptibility-weighted imaging (SWI) and qualitative diffusion-weighted imaging (DWI), in the differentiation between benign and malignant PVT. Methods: In this retrospective study, we collected clinical imaging data from 140 patients with PVTs characterized as benign or malignant based on enhanced MRI between January 2011 and April 2016 and retrospectively analyzed PVTs using SWI and DWI. There were 37 benign and 103 malignant PVTs. Image review was performed by 2 radiologists blinded to clinical information. The signal intensity (SI) of PVTs was recorded on SWI. The apparent diffusion coefficient (ADC) and the ratio of signal intensity (SIR) on SWI (SIRSWI) and ADC (SIRADC) between the PVTs and the spinal cord were calculated. Finally, we generated receiver operating characteristic (ROC) curves to evaluate the efficacy of SIRSWI and SIRADC for distinguishing benign and malignant PVTs. Results: On SWI and DWI, 100.0% (36/36) and 80.5% (29/36) of benign PVTs were hypointense, respectively. For malignant PVTs on SWI and DWI, 99.0% (103/104) and 89.4% (93/104) were hyperintense, respectively. The SIRSWI values of benign and malignant PVTs were 0.58±0.13 and 0.88±0.06, respectively, representing a significant difference (P<0.001). The SIRADC values of benign and malignant PVTs were 0.72±0.32 and 0.62±0.17, respectively, representing a significant difference (P=0.034). The area under the ROC curve (AUROC) for SIRSWI [0.990; 95% confidence interval (CI): 0.971-1.000] was significantly higher than that for SIRADC (0.619; 95% CI: 0.500-0.737; P<0.001). The SIRSWI had a sensitivity of 100.0% and a specificity of 97.3% with a cutoff value of 0.749, while the SIRADC had a sensitivity of 45.9% and specificity of 83.3% with a cutoff value of 0.791. Conclusions: The diagnostic performance of SWI is superior to that of DWI in the differentiation of benign and malignant PVTs.

A comprehensive investigation on cellulose nanocrystals with different crystal structures from cotton via an efficient route.

The crystal structures of cellulose nanomaterials play an important role in their morphologies and applications, however, there was still lacking systematic research on preparing various crystalline allomorphs of cellulose nanocrystals with high thermal stability. Herein, the efficient synthesis route was presented to design various crystalline allomorphs of cellulose from cotton. And then, cellulose nanocrystals with different crystal structures (CNC-I, CNC-II, CNC-IIIII, CNC-IVII) were prepared by hydrogen peroxide hydrolysis of resultant cellulose. Overall, needle-like CNC-I (length of 180 ± 25 nm, diameter of 12 ± 2 nm), near-spherical CNC-II (diameter of 101 ± 12 nm), and spherical CNC-IIIII (diameter of 22 ± 3 nm) and CNC-IVII (diameter of 21 ± 2 nm) all exhibited remarkable dispersibility and thermal stability (Tmax > 357 °C). This work provides a simple and low-cost synthesis route for various crystalline allomorphs of CNCs with high thermal stability from the same raw materials (cotton).

Dispersal and germination of winged seeds of Brandisia hancei, a shrub in karst regions of China.

Brandisia hancei (Paulowniaceae) is a widely distributed shrub in karst regions in southwestern China. Its seeds have a membranous wing, and they mature just before the rainy season begins. To assess the effect of the wing on seed dispersal and germination of B. hancei, we measured the dispersal distance at varying wind speeds and release heights, falling duration from different release heights, floating duration on still water, rates of imbibition of water, and drying and soil adherence to seeds. Germination experiments were conducted on intact and de-winged seeds immediately after harvest. The wing increased the falling duration in still air and the floating ability on water. Dispersal distance of winged and de-winged seeds did not differ at a wind speed of 2.8 m s-1, but at 3.6 and 4.0 m s-1 dispersal distances were greater for de-winged than for winged seeds. Seed wing had little effect of absorption and retention of water, but significantly increased soil adherence to the seeds. Mature seeds were non-dormant and germinated to over 90% with a mean germination time of about 10 days. By combining the environmental conditions in karst habitat with the seed traits of B. hancei, we conclude that dispersal and germination of winged seeds are adapted to the precipitation seasonality in heterogeneous habitats absence of soil.