Electroactive and antibacterial wound dressings based on Ti_(3)C_(2)T_(x)MXene/poly(ε-caprolactone)/gelatin coaxial electrospun nanofibrous membranes

Endogenous electric fields(EFs)are capable of regulating the behaviors of skin cells in wound healing.However,majority of current dressings are primarily engaged in the passive repair of defective tissue,as they lack the ability to actively respond to physiological electrical signals.In this work,a series of nanofibrous membranes(NFMs)were fabricated by coaxial electrospinning,combining the good mechanical properties of poly(ε-caprolactone)(PCL),the bioactivity of gelatin and the electroactivity of Ti_(3)C_(2)T_(x)MXene,as electroactive and antibacterial dressings for cutaneous wound healing.The obtained NFMs exhibited suitable mechanical properties and hydrophilicity,excellent electroactivity,antibacterial activity,and biocompatibility.Especially,Ti_(3)C_(2)T_(x)MXene/PCL/gelatin-6(MPG-6,6 wt.%of Ti_(3)C_(2)T_(x)MXene in sheath spinning liquids)showed the optimal conductivity and antibacterial activity.Excitingly,this scaffold significantly promoted the adhesion,proliferation,and migration of NIH 3T3 cells under the electrical stimulation(ES).The in vivo evaluation in a full-thickness wounds defect model demonstrated that the MPG-6 films significantly accelerated wound closure,increased granulation tissue formation,increased collagen deposition,and promoted wound vascularization.In summary,the versatile scaffold is expected to be an ideal candidate as wound dressings due to its ability to promote the transmission of physiological electrical signals and thus improved the therapeutic outcomes of wound regeneration.

Electrospun nanofiber/hydrogel composite materials and their tissue engineering applications

Electrospun nanofiber/hydrogel composites combine the excellent biochemical properties of hydrogel with the biomimetic nature of electrospun fibers,and have attracted widespread attention in the last few years.Besides,nanofiber/hydrogel composites with tunable mechanical properties can mimic the microstructure of extracellular matrix(ECM)of various tissues and the microenvironment of different cells.These features enable electrospun fiber/hydrogel composites have uniquely advantageous for tissue repair.However,a comprehensive review of electrospun fiber/hydrogel composites as tissue engineering scaffolds is still lacking.Thus,this article systematically reviewed the preparation of electrospun fiber/hydrogel composites and their application in tissue engineering.First,the preparation strategies of electrospun fiber/hydrogel composites are classified and discussed.Second,the application of electrospun fiber/hydrogel-based scaffolds in tissue engineering,involving skin,blood vessel,nerve,bone and other tissue engineering,are summarized.Finally,future research directions for functional electrospun fiber/hydrogel scaffold materials are proposed.

Current status and trends in antimicrobial use in food animals in China,2018-2020

Antimicrobial resistance poses a significant threat to global public health,and excessive antimicrobial use(AMU)in animals is a major contributing factor.We used national AMU data for food animals to examine the current status and trends for AMU in food animals in China from 2018-2020.In 2020,China used 32,776.30 tons of antimicrobials in food animals,amounting to 165 g of antimicrobials per ton of animal products.AMU in China increased throughout the 2018-2020 study period;however,the data still showed a consistent and notable reduction from those of 2017,coinciding with the implementation of the China National Action Plan for Combating Animal Antimicrobial Resistance.Among the antimicrobials used,tetracyclines,macrolides andβ-lactams(includingβ-lactam inhibitors)were the most commonly used in food animals.Analysis by antimicrobial class revealed shifts in usage patterns,such as decreased tetracycline use and increased macrolide andβ-lactam use.Furthermore,the use of antimicrobial growth promoters decreased sharply,from 51.78%in 2018 to 28.7%in 2020.Compared with AMU data from other countries,China used more antimicrobials,but the values were relatively lower when adjusted for population correction units.These findings highlight China’s remarkable efforts in combating antimicrobial resistance and promoting antimicrobial stewardship,thus contributing significantly to global initiatives.

Use of antimicrobials in food animals and impact of transmission of antimicrobial resistance on humans

Antimicrobial resistance leads to failure of clinical antimicrobial therapy,and has raised urgent global public health concern.Humans can acquire antimicrobial resistance fromdrugs through the food chain or the environment(contaminated water,air,soil,or manure).While antimicrobials have been regular supplements in animal feed that maintain health and improve productivity of livestock,their over-use in feeding forage has led to a rise in antibacterial resistance.This review summarizes the current use of antimicrobials in livestock,the harmful effects of antimicrobial resistance,and the comprehensive combat measures.

A Level Set Method for the Simulation of Moving Contact Lines in Three Dimensions

We propose an efficient numerical method for the simulation of the twophase flows with moving contact lines in three dimensions.The mathematical model consists of the incompressible Navier-Stokes equations for the two immiscible fluids with the standard interface conditions,the Navier slip condition along the solid wall,and a contact angle condition(Ren et al.(2010)[28]).In the numerical method,the governing equations for the fluid dynamics are coupledwith an advection equation for a level-set function.The latter models the dynamics of the fluid interface.Following the standard practice,the interface conditions are taken into account by introducing a singular force on the interface in themomentum equation.This results in a single set of governing equations in the whole fluid domain.Similarly,the contact angle condition is imposed by introducing a singular force,which acts in the normal direction of the contact line,into theNavier slip condition.The newboundary condition,which unifies the Navier slip condition and the contact angle condition,is imposed along the solid wall.The model is solved using the finite difference method.Numerical results are presented for the spreading of a droplet on both homogeneous and inhomogeneous solid walls,as well as the dynamics of a droplet on an inclined plate under gravity.