Microbial-inspired self-healing of concrete cracks by sodium silicate-coated recycled concrete aggregates served as bacterial carrier

Microbially induced carbonate precipitation(MICP)is a promising technique for the autonomous healing of concrete cracks.In this study,the effect of pH on MICP was investigated.The results indicate that the MICP process was inhibited when the pH was higher than 11.Both vaterite and calcite were produced when the pH was<8,whereas only calcite was produced when the pH was>8.Recycled concrete aggregates(RCA)coated with sodium silicate have been proposed as protective carriers for microbial healing agents.Although the presence of the coated RCA resulted in a loss of the splitting tension strength of the concrete,the loaded healing agents were highly efficient in self-healing cracks.Concrete incorporated with 20%RCA loaded with healing agents exhibited the best self-healing performance.When the initial crack widths were between 0.3 and 0.4 mm,the 7-d mean healing rate was approximately 90%.At 28 d,the crack area filling ratio was 86.4%,while its water tightness recovery ratio was 74.4%and 29.8%,respectively,for rapid and slow absorption.This study suggests that RCA coated with sodium silicate is an effective method for packaging microbial healing agents and has great potential for developing cost-effective self-healing concrete.

CuI/Nylon Membrane Hybrid Film with Large Seebeck Effect

Room-temperature thermoelectric materials are important for converting heat into electrical energy.As a widebandgap semiconductor material,CuI has the characteristics of non-toxicity,low cost,and environmental friendliness.In this work,CuI powder was synthesized by a wet chemical method,then CuI film was formed by vacuum assisted filtration of the CuI powder on a porous nylon membrane,followed by hot pressing.The film exhibits a large Seebeck coefficient of 600μV·K^(-1)at room temperature.In addition,the film also shows good flexibility(~95%retention of the electrical conductivity after being bent along a rod with a radius of 4 mm for 1000 times).A finger touch test on a single-leg TE module indicates that a voltage of 0.9 mV was immediately generated within 0.5 s from a temperature difference of 4 K between a finger and the environment,suggesting the potential application in wearable thermal sensors.

Fabrication, Structural and Magnetic Properties for Aligned MnBi

MnBi compound is fabricated under a magnetic field of 1 T, and the c-axis of hexagonal MnBi crystal is aligned parallel to the magnetic field direction. The saturation magnetization Ms decreases with the increase of temperature. At temperatures below 20OK, the coercive field Hc is about 150Oe, while the coercive field Hc increases with temperature above 200K. From 200K to 300K, the remnant magnetization Mr and the Mr/Ms increase with the temperature. Below 200K, Mr and Mr/M8 reach roughly a constant value. However, there is an abnormal increase at 100 K in He, Mr and Mr/Ms, which comes from a spin-reorientation in MnBi. Magnetization results show the spin-reorientation for MnBi at about 91 K due to the variations of the anisotropy constants.

Foam/Film Alternating Multilayer Structure with High Toughness and Low Thermal Conductivity Prepared via Microlayer Coextrusion

Multilayer membranes prepared via microlayer coextrusion have attracted wide attention due to their unique properties and broad applications.In present study,the foam/film alternating multilayer sheets based on ethylene-vinyl acetate copolymer(EVA)and high-density polyethylene are successfully prepared via microlayer coextrusion.The cells in the sheets are single-cell-array along the foamed EVA layers with uniform cell size.In addition,the effects of layer number and foam relative thickness on morphology,mechanical properties,damping and heat insulation properties are investigated.The cell size decreases significantly with increasing layer number due to the enhanced confine effects.The tensile strength,elongation at break,and heat insulation also increase significantly.However,the mechanical damping properties change little in the observed frequency.Meanwhile,with higher relative thickness of EVA foam,the sheets have lower tensile strength and lower thermal conductivity,while the damping properties are enhanced in a specific frequency scope.The elongation at break of the optimized sample comes to 800%and the thermal conductivity decreases to 61 mW·m^(-1)·K^(-1),which shows high toughness and low thermal conductivity,indicating a possible method for preparing materials with high toughness and heat-insulating properties.