Strain engineering in electrocatalysis:Strategies,characterization,and insights

Strain engineering,as a cutting-edge method for modulating the electronic structure of catalysts,plays a crucial role in regulating the interaction between the catalytic surface and the adsorbed molecules.The electrocatalytic performance is influenced by the electronic structure,which can be achieved by introducing the external forces or stresses to adjust interatomic spacing between surface atoms.The challenges in strain engineering research lie in accurately understanding the mechanical impact of strain on performance.This paper first introduces the basic strategy for generating the strain,summarizes the different strain generation forms and their advantages and disadvantages.The progress in researching the characterization means for the lattice strains and their applications in the field of electrocatalysis is also emphasized.Finally,the challenges of strain engineering are introduced,and an outlook on the future research directions is provided.

Strain Gradient Finite Element Formulation of Flexoelectricity in Ferroelectric Material Based on Phase-Field Method

Flexoelectricity is a two-way coupling effect between the strain gradient and electric field that exists in all dielectrics,regardless of point group symmetry.However,the high-order derivatives of displacements involved in the strain gradient pose challenges in solving electromechanical coupling problems incorporating the flexoelectric effect.In this study,we formulate a phase-field model for ferroelectric materials considering the flexoelectric effect.A four-node quadrilateral element with 20 degrees of freedom is constructed without introducing high-order shape functions.The microstructure evolution of domains is described by an independent order parameter,namely the spontaneous polarization governed by the time-dependent Ginzburg–Landau theory.The model is developed based on a thermodynamic framework,in which a set of microforces is introduced to construct the constitutive relation and evolution equation.For the flexoelectric part of electric enthalpy,the strain gradient is determined by interpolating the mechanical strain at the node via the values of Gaussian integration points in the isoparametric space.The model is shown to be capable of reproducing the classic analytical solution of dielectric materials incorporating the flexoelectric contribution.The model is verified by duplicating some typical phenomena in flexoelectricity in cylindrical tubes and truncated pyramids.A comparison is made between the polarization distribution in dielectrics and ferroelectrics.The model can reproduce the solution to the boundary value problem of the cylindrical flexoelectric tube,and demonstrate domain twisting at domain walls in ferroelectrics considering the flexoelectric effect.

Anti-inflammatory and DNA Repair Effects of Astragaloside IV on PC12 Cells Damaged by Lipopolysaccharide

Objective This study aimed to establish a neural cell injury model in vitro by stimulating PC12 cells with lipopolysaccharide(LPS)and to examine the effects of astragaloside IV on key targets using high-throughput sequence technology and bioinformatics analyses.Methods PC12 cells in the logarithmic growth phase were treated with LPS at final concentrations of 0.25,0.5,0.75,1,and 1.25 mg/mL for 24 h.Cell morphology was evaluated,and cell survival rates were calculated.A neurocyte inflammatory model was established with LPS treatment,which reached a 50%cell survival rate.PC12 cells were treated with 0.01,0.1,1,10,or 100µmol/L astragaloside IV for 24 h.The concentration of astragaloside IV that did not affect the cell survival rate was selected as the treatment group for subsequent experiments.NOS activity was detected by colorimetry;the expression levels of ERCC2,XRCC4,XRCC2,TNF-α,IL-1β,TLR4,NOS and COX-2 mRNA and protein were detected by RT-qPCR and Western blotting.The differentially expressed genes(DEGs)between the groups were screened using a second-generation sequence(fold change>2,P<0.05)with the following KEGG enrichment analysis,RT-qPCR and Western blotting were used to detect the mRNA and protein expression of DEGs related to the IL-17 pathway in different groups of PC12 cells.Results The viability of PC12 cells was not altered by treatment with 0.01,0.1,or 1µmol/L astragaloside IV for 24 h(P>0.05).However,after treatment with 0.5,0.75,1,or 1.25 mg/mL LPS for 24 h,the viability steadily decreased(P<0.01).The mRNA and protein expression levels of ERCC2,XRCC4,XRCC2,TNF-α,IL-1β,TLR4,NOS,and COX-2 were significantly increased after PC12 cells were treated with 1 mg/mL LPS for 24 h(P<0.01);however,these changes were reversed when PC12 cells were pretreated with 0.01,0.1,or 1µmol/L astragaloside IV in PC12 cells and then treated with 1 mg/mL LPS for 24 h(P<0.05).Second-generation sequencing revealed that 1026 genes were upregulated,while 1287 genes were downregulated.The DEGs were associated with autophagy,TNF-α,interleukin-17,MAPK,P53,Toll-like receptor,and NOD-like receptor signaling pathways.Furthermore,PC12 cells treated with a 1 mg/mL LPS for 24 h exhibited increased mRNA and protein expression of CCL2,CCL11,CCL7,MMP3,and MMP10,which are associated with the IL-17 pathway.RT-qPCR and Western blotting analyses confirmed that the DEGs listed above corresponded to the sequence assay results.Conclusion LPS can damage PC12 cells and cause inflammatory reactions in nerve cells and DNA damage.astragaloside IV plays an anti-inflammatory and DNA damage protective role and inhibits the IL-17 signaling pathway to exert a neuroprotective effect in vitro.

All-in-one cellulose based hybrid tribo/piezoelectric nanogenerator

Aybrid tribo/piezoelectric nanogenerators (HTPENG) have been proven to be highly efficient and versatile as far as the collection and conversion of ambient energy are concerned, and the introduction of flexible and green materials is a key step for their potential applications. Here, we developed a HTPENG by using nitrocellulose nanofibril paper as the triboelectric layer and BaTiCVMWCNT@ bacterial cellulose paper as the piezoelectric layer. The output of the triboelelctric paper has considerable performance as fluorinated ethylene propylene, and the output of piezoelectric paper is more than ten times higher than the BTO/polydimethylsiloxane structure. The integrated outputs of the sandwich structured HTPENG are 18 V and 1.6 pA·cm^-2, which are capable of lighting up three LED bulbs and charging a 1 pF capacitor to 2.5 V in 80 s. In addition, the voltage signal generated by the HTPENG in contact-separation mode can be used for dynamic pressure detection. The linear range of dynamic pressure is from 0.5 to 3 N·cm^-2 with a high sensitivity of 8.276 V·cm^-2·N^-1 and a detection limit of 0.2 N·cm^-2. This work provides new insights into the design and application of cellulose-based hybrid nanogenerators with high flexibility and simple structure.