A mechanically stable self-pumping organohydrogel dressing with aligned microchannels for accelerated diabetic wound healing

Self-pumping dressings(SPDs)have been developed as a new type of effective material for the drainage of excessive wound exudates based on the structure of asymmetric wettability.However,current SPDs are easy to lose their asymmetric wettability due to the weak interfacial mechanical stability between the hydrophobic and hydrophilic layers.Herein,we report an integrated self-pumping organohydrogel dressing with aligned microchannels(SPD-AM),prepared by an ice-templating-assisted wetting-enabled-transfer(WET)polymerization strategy,that can accelerate the healing process of diabetic wounds.The WET polymerization strategy enables strong interfacial mechanical stability between the hydrophobic organogel and hydrophilic hydrogel layers.The aligned microchannels greatly improve the draining capability of SPDs.Taking a diabetic rat model as an example,the SPD-AM can significantly reduce the bacterial colonization with low inflammatory responses,enhance dermal remodeling by about 47.31%,and shorten wound closure time by about 1/5 compared with other dressings,ultimately accelerating diabetic wound healing.This study is valuable for developing next-generation SPDs with stable mechanical performance for clinical applications.

Stabilizing Mechanism and Running Behavior of Couplers on Heavy Haul Trains

Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train forces generated by longitudinal in-train forces and coupler rotations have become a more and more significant safety issue for heavy haul train operations. Derailments caused by excessive lateral in-train forces are frequently reported. This article studies two typical coupler systems used on heavy haul locomotives. Their structures and stabilizing mechanism are analyzed before the corresponding models are developed. Coupler systems models are featured by two distinct stabilizing mechanism models and draft gear models with hysteresis considered. A model set which consists of four locomotives and three coupler systems is developed to study the rotational behavior of different coupler systems and their implications for locomotive dynamics. Simulated results indicate that when the locomotives are equipped with the type B coupler system, locomotives can meet the dynamics standard on tangent tracks; while the dynamics performance on curved tracks is very poor. The maximum longitudinal in-train force for locomotives equipped with the type B coupler system is 2000 kN. Simulations revealed a distinct trend for the type A coupler system. Locomotive dynamics are poorer for the type A case when locomotives are running on tangent tracks, while the dynamics are better for the type A case when locomotives are running on curved tracks. Theoretical studies and simulations carried out in this article suggest that a combination of the two types of stabilizing mechanism can result in a good design which can significantly decrease the relevant derailments.