Carnivorous plants inspired shape-morphing slippery surfaces

Carnivorous plants,for instance,Dionaea muscipula and Nepenthes pitcher plant,inspired the innovation of advanced stimuli-responsive actuators and lubricant-infused slippery surfaces,respectively.However,hybrid bionic devices that combine the active and passive prey trapping capabilities of the two kinds of carnivorous plants remain a challenge.Herein,we report a moisture responsive shape-morphing slippery surface that enables both moisture responsive shapemorphing and oil-lubricated water repellency for simultaneous active-and passive-droplet manipulation.The moisture deformable slippery surface is prepared by creating biomimetic microstructures on graphene oxide(GO)membrane via femtosecond laser direct writing and subsequent lubricating with a thin layer of oil on the laser structured reduced GO(LRGO)surface.The integration of a lubricant-infused slippery surface with an LRGO/GO bilayer actuator endows the actuator with droplet sliding ability and promotes the moisture deformation performance due to oil-enhanced water repellency of the inert layer(LRGO).Based on the shape-morphing slippery surface,we prepared a series of proof-of-concept actuators,including a moisture-response Dionaea muscipula actuator,a smart frog tongue,and a smart flower,demonstrating their versatility for active/passive trapping,droplet manipulation,and sensing.

Quantitative models for microstructure and thermal conductivity of vermicular graphite cast iron cylinder block based on cooling rate

The relationships of cooling rate with microstructure and thermal conductivity of vermicular graphite cast iron(VGI) cylinder block were studied, which are important for design and optimization of the casting process of VGI cylinder blocks. Cooling rates at different positions in the cylinder block were calculated based on the cooling curves recorded with a solidification simulation software. The metallographic structure and thermal conductivity were observed and measured using optical microscopy(OM), scanning electrical microscopy(SEM) and laser flash diffusivity apparatus, respectively. The effects of the cooling rate on the vermicularity, total and average areas of all graphite particles, and the pearlite fraction in the VGI cylinder block were investigated. It is found that the vermicularity changes in parabola trend with the increase of cooling rate. The total area of graphite particles and the cooling rate at eutectoid stage can be used to predict pearlite fraction well. Moreover, it is found that the thermal conductivity at room temperature is determined by the average area of graphite particles and pearlite fraction when the range of vermicularity is from 80% to 93%. Finally, the quantitative models are established to calculate the vermicularity, pearlite fraction, and thermal conductivity of the VGI cylinder block.

Prediction of high-mobility two-dimensional electron gas at KTaO_3-based heterointerfaces

First-principles calculations are performed to explore the possibility of generating the two-dimensional electron gas(2 DEG) at the interface between LaGaO_3/KTaO_3 and NdGaO_3/KTaO_3(001) heterostructures. Two different models —i.e., the superlattice model and the thin film model — are used to conduct a comprehensive investigation of the origin of charge carriers. For the symmetric superlattice model, the LaGaO_3(or NdGaO_3) film is nonpolar. The 2 DEG with carrier density on the order of 1014 cm^(-2) originates from the Ta dxy electrons contributed by both LaGaO_3(or NdGaO_3) and KTaO_3. For the thin film model, large polar distortions occur in the LaGaO_3 and NdGaO_3 layer, which entirely screens the built-in electric field and prevents electrons from transferring to the interface. Electrons of KTaO_3 are accumulated at the interface, contributing to the formation of the 2 DEG. All the heterostructures exhibit conducting properties regardless of the film thickness. Compared with the Ti dxy electrons in SrTiO_3-based heterostructures, the Ta dxy electrons have small effective mass and they are expected to move with higher mobility along the interface. These findings reveal the promising applications of 2 DEG in novel nanoelectronic devices.

Multiple-valley effect on modulation of thermoelectric properties of n-type ZrCuSiAs-structure oxyantimonides LnTSbO(Ln=lanthanides and T=Zn,Mn)

Thermoelectric properties of n-type LnTSbO(Ln=lanthanides and T?Zn,Mn)were firstly investigated by the first-principles method and the semi-classical Boltzmann theory.The results show that a multiplevalley structure appears around the bottom of conduction band.The valley with a high band degeneracy consists of the bands with a weak band dispersion,leading to large magnitudes of the Seebeck coefficient but low electrical conductivity.The valley with a low band degeneracy is made up of the bands with an intense band dispersion,resulting in a high electrical conductivity but small magnitudes of the Seebeck coefficient.The thermoelectric properties are dominated by the energy difference,DE,between the valleys.The DE value of LnZnSbO linearly increases with the ionic radius of Ln.The thermoelectric properties are thus effectively modulated by varying the lanthanides.As a result,LnZnSbO(Ln?Ce-Nd)with the moderate values of DE shows a better thermoelectric performance.The multiple-valley effect is an effective way to modulate the thermoelectric properties of n-type LnTSbO.