Bioinspired Multifunctional Self-Sensing Actuated Gradient Hydrogel for Soft-Hard Robot Remote Interaction

The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO_(2) nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation(21° s^(-1)) and enhanced photothermal efficiency(increase by 3.7 ℃ s^(-1) under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca^(2+) endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity(gauge factor 3.94 within a wide strain range of 600%), fast response times(140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.

温度和pH双重响应的改性纳米纤维素制备及表征

通过表面引发单电子转移活性自由基聚合和自由基聚合法,分别将N-异丙基丙烯酰胺(NIPAM)和丙烯酸(AA)接枝聚合到纤维素纳米晶(CNCs)的羟基上,制备了PNIPAM和PAA双重接枝的改性CNCs(PNIPAM-g-CNCs-gPAA)。利用红外光谱(FT-IR)、热重分析(TGA)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见光分光光度计(UV-Vis)和粒度仪等对改性CNCs进行了测试表征。FT-IR和XPS分析证实了改性CNCs的成功制备;TEM显示改性CNCs依旧保留棒状晶体形态但直径变宽;TGA表明改性CNCs的热稳定性较CNCs有显著提升;UV-Vis分析改性CNCs的低临界相转变温度(LCST)约为37℃,此时该纳米颗粒发生体积收缩,粒径收缩为原来的68%,且随着温度的提高,完成体积相转变的时间越短,此外该温度响应具有可逆性;UV-Vis对pH响应测试可知,在pH<5时,悬浮液的光透过率显著下降,表明接枝后的CNCs在强酸性条件下易团聚,而在中碱性环境下,亲水性良好,该p H响应具有可逆性。温度和pH双重响应的改性CNCs以期应用于如智能药物缓释、智能响应开关膜等领域。

Sulfur and carbon co-doped g-C_(3)N_(4)microtubes with enhanced photocatalytic H2 production activity

Metal-free graphitic carbon nitride(g-C_(3)N_(4))has captured significant attention as a low-cost and efficient hydrogen production photocatalyst through.Effectively regulating the microstructure and accelerating the separation of photogenerated carriers remain crucial strategies for promoting the photocatalytic performance of this material.Herein,a novel sulfur–carbon co-doped g-C_(3)N_(4)(SCCN)hierarchical microtubules filled with abundant nanosheets inside by thermal polymerization is reported.Numerous nanosheets create abundant pores and cavities inside the SCCN microtubes,thereby increasing the specific surface area of g-C_(3)N_(4)and providing sufficient reactant attachment sites.Besides,the hierarchical structure of SCCN microtubules strengthens the reflection and scattering of light,and the utilization of visible light is favorably affected.More importantly,co-doping S and C has greatly improved the photocatalytic performance of graphitic carbon nitride,optimized the band gap structure and enhanced the photogenerated carrier splitting.Consequently,the SCCN exhibits a remarkable photocatalytic H_(2)evolution rate of 4868μmol/(g·h).This work demonstrates the potential of multi-nonmetal doped g-C_(3)N_(4)as the ideal photocatalyst for H2 evolution.

Application of Peps in Stress Analysis of Nuclear Piping

According to the nuclear safety regulations, this paper discusses the mechanical analysis method for piping system. Peps program has advantages of stress analysis and evaluation for nuclear piping. First, this paper introduces the Peps software, and discusses the process of stress analysis and evaluation for nuclear piping using the general finite element software;Secondly, taking nuclear class 2/3 piping system as an example, it uses Peps4.0 program to calculate the piping stress in variety of working conditions, such as weight, pressure, thermal expansion, earthquake, time-history force, and etc. Finally, the paper calculates the maximum stress and stress ratio according to the ASME.

Study on Seismic Fragility Analysis for Piping of CEFR

This paper introduces the conception of seismic fragility, gives the model of seismic fragility analysis, and places emphasis on discussing quantization process of seismic fragility parameters. Then, establishes 3D model of pipes of Chinese Experimental Fast Reactor (CEFR) accident residual heat removal system, and obtains the stresses which are essential for calculating seismic fragility parameters. Finally, combined with quantitative methods of seismic fragility, calculates the safety factors and uncertainties of CEFR pipeline, and obtains the system seismic fragility parameters: Am = 2.42 g, βr = 0.36, βu = 0.44, HCLPF = 0.65 g. The results show that: the pipeline of CEFR accident residual heat removal system has high seismic capacity.

Fluorinated Covalent Organic Frameworks Coupled with Molecular Cobalt Cocatalysts for Efficient Photocatalytic CO_(2)Reduction

The combination of covalent organic framework(COF)photosensitizers with molecular cocatalysts is a promising avenue for photocatalytic carbon dioxide(CO_(2))reduction.Here,a series of isostructural COFs was synthesized using linkers of different lengths,with or without partial fluorination.These COFs were investigated for photocatalytic CO_(2)reduction under visible-light irradiation when combined with cobalt(II)bipyridine complexes as a cocatalyst.Fluorination was found to enhance both CO_(2)affinity and catalytic activity,and a partially fluorinated COF,FBP-COF,achieved the highest CO_(2)-to-CO conversion efficiency,showing a carbon monoxide(CO)generation rate of 2.08 mmol h−1 g−1 and a 90%CO selectivity.FBP-COF also showed good stability under sacrificial conditions,generating CO for 50 h with a turnover number of 91.5.This activity is much higher than a homogeneous system using ruthenium bipyridine complexes as the photosensitizer combined with the same cobalt bipyridine complexes.

Thermal property evaluation of a 2.5D integration method with device level microchannel direct cooling for a high-power GaN HEMT device

Gallium nitride high electron mobility transistor(GaN HEMT)devices have become critical components in the manufacturing of high-performance radio frequency(RF)or power electronic modules due to their superior characteristics,such as high electron saturation speeds and high power densities.However,the high heat characteristics of GaN HEMTs make device level cooling a critical problem to solve since performance degradation or even failure may occur under high temperatures.In this paper,we proposed a 2.5D integration method with devicelevel microchannel direct cooling for a high-power GaN HEMT device.To demonstrate this technological concept,a multigate GaN HEMT device featuring a gate length/width/source drain spacing of 0.5μm/300μm/6μm that underwent in-house backside thinning and metallization was used as the test vehicle.A high-resistivity silicon(HR Si)interposer embedded with four-layer microchannels was designed,having widths/pitches of 30μm/30μm at the top microchannel.The high-power GaN HEMT device was soldered on a Si interposer embedded with open microchannels for heat dissipation.A pair of GSG Pad chips was soldered simultaneously to display the capacity for the heterogeneous integration of other chip types.Thermal property evaluation was conducted with experiments and simulations.The test results showed that the maximum surface temperature of the GaN HEMT device decreased to 93.8°C when it experienced a heat dissipation density of 32 kW/cm^(2) in the gate finger area and an average heat dissipation density of 5 kW/cm^(2) was found in the active area with the DI water coolant at a flow rate of 3 mL/min.To our knowledge,among recently reported works,this finding was the best cooling capacity of heterogeneously integrated microchannels for GaN HEMT devices.In addition,this technology was scalable regarding the numbers of gate fingers or GaN HEMT devices.

Ultra-high temperature tolerant flexible transparent electrode with embedded silver nanowires bundle micromesh for electrical heater

To realize high performance flexible transparent electronics with extreme environmental adaptivity,Ag nanowires(Ag NWs)electrodes should simultaneously meet the requirements of high-temperature tolerance,chemical and mechanical robustness.Herein,a scalable Ag NWs bundle micro-meshes embedded in polyimide(Ag BMs/ePI)conducting film via a facile spray coating and transfer method is reported.Due to the synergistic effect of bundle micromesh and embedded architecture,the Ag BMs/ePI electrode exhibits high thermal stability(370℃ and 400℃ under ambient and nitrogen atmosphere conditions,respectively),low sheet resistance variation(<4%),good corrosion and deformation resistance.As an electrical heater,the Ag BMs/ePI can achieve~204℃ with the fast thermal response time of~8 s at 8 V,and exhibits good heating stability under bent condition.This work offers a promising platform for the emerging flexible transparent electronics to adapt extreme environments,especially for those devices which require high-temperature processing.