A Novel Method of Fabricating Flexible Transparent Conductive Large Area Graphene Film

We fabricate flexible conductive and transparent graphene films on position-emission-tomography substrates and prepare large area graphene films by graphite oxide sheets with the new technical process. The multi-layer graphene oxide sheets can be chemically reduced by HNO3 and HI to form a highly conductive graphene film on a substrate at lower temperature. The reduced graphene oxide sheets show a high conductivity sheet with resistance of 476Ω/sq and transmittance of 76% at 550nm （6 layers）. The technique used to produce the transparent conductive graphene thin film is facile, inexpensive, and can be tunable for a large area production applied for electronics or touch screens.

Meltblown fabric vs nanofiber membrane, which is better for fabricating personal protective equipments

The coronavirus disease 2019(COVID-19)pandemic has led to a great demand on the personal protection products such as reusable masks.As a key raw material for masks,meltblown fabrics play an important role in rejection of aerosols.However,the electrostatic dominated aerosol rejection mechanism of meltblown fabrics prevents the mask from maintaining the desired protective effect after the static charge degradation.Herein,novel reusable masks with high aerosols rejection efficiency were fabricated by the introduction of spider-web bionic nanofiber membrane(nano cobweb-biomimetic membrane).The reuse stability of meltblown and nanofiber membrane mask was separately evaluated by infiltrating water,75%alcohol solution,and exposing under ultraviolet(UV)light.After the water immersion test,the filtration efficiency of meltblown mask was decreased to about 79%,while the nanofiber membrane was maintained at 99%.The same phenomenon could be observed after the 75%alcohol treatment,a high filtration efficiency of 99%was maintained in nanofiber membrane,but obvious negative effect was observed in meltblown mask,which decreased to about 50%.In addition,after long-term expose under UV light,no filtration efficiency decrease was observed in nanofiber membrane,which provide a suitable way to disinfect the potential carried virus.This work successfully achieved the daily disinfection and reuse of masks,which effectively alleviate the shortage of masks during this special period.

Engineering strontium aluminate sacrificial layers for fabricating monocrystalline complex oxide freestanding membranes

There was a long history of releasing various monocrystalline semiconductor structures from their hosting substrates to form“freestanding”structures,in order to change the substrates and for other special purposes.The release was achieved by breaking the bonds between the film and the substrate,through methods such as forming interfacial gas bubbles(“smart-cut”technology for fabricating semiconductor-on-insulator wafers)or chemical etching(selectively etching epitaxial AlAs underlayer for fabricating GaAs-on-silicon photonic devices).The exfoliation of layered van der Waals materials in recent decades also produced another class of freestanding monocrystalline materials—twodimensional(2D)materials.In addition to changeable substrates,being freestanding also allowed unique methods to manipulate the 2D materials;for example,transferring them on flexible substrates and directly stretching them controls the strain in their lattice,as well as their strain-dependent physical properties.

Fabricating a smart clothing system based on strain-sensing yarn and novel stitching technology for health monitoring

Various yarn-shaped flexible strain sensors have recently been developed.However,research is lacking on additive manufacturing for smart clothing for integrating yarn sensors with commercial garments.Herein,a strain-sensing yarn is sewn into a piece of fabric through a novel stitching technique,and the influence of the stitching method and needle pitch on the sensing performance is investigated using finite element analysis(FEA).The sensing performance could be improved when the sensing yarn is self-locked in the fabric at the needle eyes,and the needle pitch was reduced to 0.5 cm,which is attributed to the enhanced stress and strain concentration.Meanwhile,the composite sensing fabric featured outstanding performance,including a low detection limit(0.1%),rapid response(280 ms),excellent durability(10000 cycles),and high stability(negligible drift and frequency independence).In addition,the remarkable wear resistance,washability,and anti-interference to ambient humidity and perspiration were obtained.Therein,the optimal stitch trace lengths of sensing yarn for detecting elbow motion,breathing,and heartbeats are discussed.Finally,a smart clothing system composed of smart clothing,data acquisition unit,and mobile APP was developed to simultaneously detect human movement and physiological signals.This work provides a reference to produce intelligent garments based on yarn sensors for health monitoring.

Low-cost method of fabricating large-aperture,high efficiency,Fresnel diffractive membrane optic using a modified moir technique

To reduce the cost and achieve high diffraction efficiency, a modified moir@ technique for fabricating a large- aperture multi-level Fresnel membrane optic by a novel design of alignment marks is proposed. The modified moire fringes vary more sensitively with the actual misalignment. Hence, the alignment accuracy is significantly improved. Using the proposed method, a 20 μm thick, four-level Fresnel diffractive polyimide membrane optic with a 200 mm diameter is made, which exhibits over 62% diffraction efficiency into the ＋1 order, and an efficiency root mean square of 0.051.

Smart Cellulose‑Based Janus Fabrics with Switchable Liquid Transportation for Personal Moisture and Thermal Management

The Janus fabrics designed for personal moisture/thermal regulation have garnered significant attention for their potential to enhance human comfort.However,the development of smart and dynamic fabrics capable of managing personal moisture/thermal comfort in response to changing external environments remains a challenge.Herein,a smart cellulose-based Janus fabric was designed to dynamically manage personal moisture/heat.The cotton fabric was grafted with N-isopropylacrylamide to construct a temperature-stimulated transport channel.Subsequently,hydrophobic ethyl cellulose and hydrophilic cellulose nanofiber were sprayed on the bottom and top sides of the fabric to obtain wettability gradient.The fabric exhibits anti-gravity directional liquid transportation from hydrophobic side to hydrophilic side,and can dynamically and continuously control the transportation time in a wide range of 3–66 s as the temperature increases from 10 to 40℃.This smart fabric can quickly dissipate heat at high temperatures,while at low temperatures,it can slow down the heat dissipation rate and prevent the human from becoming too cold.In addition,the fabric has UV shielding and photodynamic antibacterial properties through depositing graphitic carbon nitride nanosheets on the hydrophilic side.This smart fabric offers an innovative approach to maximizing personal comfort in environments with significant temperature variations.

Fabricating lifted Haar transform image compression optical chip based on femtosecond laser

In this paper,a lifted Haar transform(LHT)image compression optical chip has been researched to achieve rapid image compression.The chip comprises 32 same image compression optical circuits,and each circuit contains a 2×2 multimode interference(MMI)coupler and aπ/2 delay line phase shifter as the key components.The chip uses highly borosilicate glass as the substrate,Su8 negative photoresist as the core layer,and air as the cladding layer.Its horizontal and longitudinal dimensions are 8011μm×10000μm.Simulation results present that the designed optical circuit has a coupling ratio(CR)of 0:100 and an insertion loss(IL)of 0.001548 d B.Then the chip is fabricated by femtosecond laser and testing results illustrate that the chip has a CR of 6:94 and an IL of 0.518 d B.So,the prepared chip possesses good image compression performance.

Advanced optical methods and materials for fabricating 3D tissue scaffolds

Three-dimensional(3D)printing,also known as additive manufacturing(AM),has undergone a phase of rapid development in the fabrication of customizable and high-precision parts.Thanks to the advancements in 3D printing technologies,it is now a reality to print cells,growth factors,and various biocompatible materials altogether into arbitrarily complex 3D scaffolds with high degree of structural and functional similarities to the native tissue environment.Additionally,with overpowering advantages in molding efficiency,resolution,and a wide selection of applicable materials,optical 3D printing methods have undoubtedly become the most suitable approach for scaffold fabrication in tissue engineering(TE).In this paper,we first provide a comprehensive and up-to-date review of current optical 3D printing methods for scaffold fabrication,including traditional extrusion-based processes,selective laser sintering,stereolithography,and two-photon polymerization etc.Specifically,we review the optical design,materials,and representative applications,followed by fabrication performance comparison.Important metrics include fabrication precision,rate,materials,and application scenarios.Finally,we summarize and compare the advantages and disadvantages of each technique to guide readers in the optics and TE communities to select the most fitting printing approach under different application scenarios.

Non-coplanar multi-beam interference produced by one triangular pyramid for fabricating photonic crystals

A method for fabricating three-dimensional （3D） photonic crystals （PhCs） easily and simply, by using a visible light （- 532 nm） to pass one triangular pyramid to form non-coplanar multi-beam interference, named laser interference etching technique, is reported. In the experiment, we exposed a 9-μm-thick photo- resist on the silicon substrate with exposure intensities of 150, 180, and 220 mJ/cm^2, and produced the periodical nanostructures. Through varying a common angle in the triangular pyramid, other interference patterns can be obtained to fabricate various PhCs.

Localized in‑situ deposition:a new dimension to control in fabricating surface micro/nano structures via ultrafast laser ablation

Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications.As a versatile approach,ultrafast laser ablation has been widely studied for surface micro/nano structuring.Increasing research eforts in this feld have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex structures.In this paper,we focus on the in-situ deposition process following the plasma formation under ultrafast laser ablation.From an overview perspective,we frstly summarize the diferent roles that plasma plumes,from pulsed laser ablation of solids,play in diferent laser processing approaches.Then,the distinctive in-situ deposition process within surface micro/nano structuring is highlighted.Our experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures,through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a showcase.The revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches,adding a new dimension and more fexibility in controlling the fabrication of functional surface micro/nano structures.

基于区块链和HACCP的水产品溯源系统

针对传统的水产品溯源中心化严重、数据易被篡改等问题,运用区块链技术,基于危害分析与关键控制点(HACCP)设计水产品溯源体系.采用多元线性回归的方法对样品数据指标进行处理,确认了养殖过程中的关键控制点;在确定关键信息的基础上,设计了智能合约对水产品溯源各环节的上传数据进行判定.从系统可行性出发,分别对系统功能、共识拓扑、溯源编码进行详细设计.搭建水产品溯源系统,并对系统的功能和性能进行了测试.结果表明:系统的交易吞吐量固定在320笔/s上下,平均交易延迟在0.5 s左右,交易成功率在99.8%左右,完全可以满足生产实践的需求.

一种面向联盟链Hyperledger Fabric的并发冲突事务优化方法

随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向块内冲突的方案缺乏高效的冲突检测和避免方法,同时现有研究往往忽略区块间冲突对吞吐量的不利影响.提出了一种Fabric的优化方案Fabric-HT(fabric with high throughput),从区块内和区块间2方面入手,有效降低事务间并发冲突和提高系统吞吐量.针对区块内事务冲突,提出了一种事务调度机制,根据块内冲突事务集定义了一种高效数据结构——依赖关系链,识别具有“危险结构”的事务并提前中止,合理调度事务和消除冲突;针对区块间事务冲突,将冲突事务检测提前至排序节点完成,建立以“推送-匹配”为核心的冲突事务早期避免机制.在多场景下开展大量实验,结果表明Fabric-HT在吞吐量、事务中止率、事务平均执行时间、无效事务空间占用率等方面均优于对比方案.Fabric-HT吞吐量最高可达Fabric的9.51倍,是最新优化方案FabricSharp的1.18倍;空间利用率上相比FabricSharp提升了14%.此外,Fabric-HT也表现出较好的鲁棒性和抗攻击能力.

Electricity Generation from Heatwaves

We chose a definition of heatwaves (HWs) that has ~4-year recurrence frequency at world hot spots. We first examined the 1940-2022 HWs climatology and trends in lifespan, severity, spatial extent, and recurrence frequency. HWs are becoming more frequent and more severe for extratropical mid- and low-latitudes. To euphemize HWs, we here propose a novel clean energy-tapping concept that utilizes the available nano-technology, micro-meteorology knowledge of temperature distribution within/without buildings, and radiative properties of earth atmosphere. The key points for a practical electricity generation scheme from HWs are defogging, insulation, and minimizing the absorption of infrared downward radiation at the cold legs of the thermoelectric generators. One sample realization is presented which, through relay with existing photovoltaic devices, provides all-day electricity supply sufficient for providing air conditioning requirement for a residence (~2000-watt throughput). The provision of power to air conditioning systems, usually imposes a significant stress on traditional city power grids during heatwaves.

基于Fabric的海量交易数据上链预处理机制

Hyperledger Fabric是一种国内外广泛使用的联盟链框架,在基于Fabric技术的一些业务中具有协同组织众多、交易操作频繁、事务冲突增加等特点。Fabric采用的多版本并发控制技术能够在一定程度上解决部分交易冲突,提升系统并发性,但其机制不完善,会出现部分交易数据无法正常上链存储的问题。为了实现海量交易数据完整、高效、可信的上链存储,提出一种基于Fabric预言机的数据上链预处理机制。设计海量数据冲突预处理(MCPP)方法,通过检测、监听、延时提交、事务加锁、重排序缓存等方式实现主键冲突交易数据的完整上链。引入数据传输保障措施,在传输过程中利用非对称加密技术防止恶意节点伪造认证信息,确保交易数据链外处理前后的一致性。通过理论分析和实验结果表明,该机制可有效解决联盟链平台中海量交易数据上链时的并发冲突问题,当交易数据规模达到1 000和10 000时,MCPP的时效性比LMLS提高了38%和21.4%,且成功率接近100%,具有高效性和安全性,同时在无并发冲突情况下不影响Fabric系统性能。

基于CP-ABE算法的Fabric隐私保护模型

传统区块链系统缺少对区块数据的隐私保护。结合CP-ABE(基于属性加密的密文策略)算法和IPFS(星际文件系统),提出一种可以对Fabric区块链实现访问控制的隐私保护模型CP-PPM。CP-PPM的数据所有者可以灵活设置访问控制策略。仿真结果表明,与现有Fabric区块链系统相比,CP-PPM模型支持细粒度的访问控制,具有更强的隐私保护效果;CP-ABE算法可以安全初始化,对数据的加解密效率更高,同时增强了区块链系统的存储性能。

生态流量监测系统的区块链框架设计及管理模块实现

河湖生态流量保障工作是全面推行河湖长制、实行最严格水资源管理制度的重要内容,确保生态流量监测数据在多部门流转过程中的可信与安全共享尤其重要。针对生态流量监测数据应用和共享的多样化、差异化、动态化需求,结合区块链技术的优点,在生态流量监测系统中引入Hyperledger Fabric平台的可插拔式区块链组件,构建了包含基础系统层、区块链中枢层、区块链服务支撑层、业务应用层的四层联盟链系统架构,围绕链上数据的可信安全共享及溯源需求,设计实现了区块链系统用户管理、数据及文件操作、区块链浏览三个功能模块,开发了区块链信息查看功能页面并集成至水库水情测报系统中。可插拔式区块链支撑组件的引入,便于对已建信息化平台进行区块链技术改造,能有效降低开发成本和周期及运维成本。该研究是区块链技术在水资源监管领域的初步探索,可为提升水资源管理能力提供新的技术思路与方案。

HLF区块链交易时延动态优化方法研究

Hyperledger Fabric(HLF)性能优化是区块链研究的热点问题,但当前工作对低负载生产环境中的交易时延关注不足,成为影响联盟链落地应用的重要因素。针对这一问题,提出了面向HLF的交易时延动态自适应优化方法:综合考虑交易到达率与交易大小维度,对HLF(v2.2)进行全面的性能评估,并给出了一组静态推荐配置参数;基于性能评估数据,使用XGBoost建立HLF性能模型,获得应用负载、网络配置、交易时延间的映射关系;对非饱和动态负载与突发注入攻击等场景进行模拟,获得贴近生产环境的应用负载输入;基于贝叶斯优化算法,对HLF进行动态自适应配置参数优化,有效降低HLF交易处理时延。通过实验,验证了优化方法的有效性,在多组随机动态负载输入中取得了平均53%、最高97%的交易时延优化效果。

基于区块链的水产交易计量数据采集与传输研究

为解决目前水产交易中手动录入计量数据易篡改、易丢失的问题,本研究提出一种基于区块链技术的水产交易计量数据采集与传输安全模型。首先设计一套基于树莓派的数据采集平台,用于数据的自动采集和录入;其次通过智能合约和共识机制保证所采集交易数据的传输与存储安全;最后,基于区块链技术设计一套水产交易计量数据采集与传输系统,实现水产交易计量数据采集和查询等功能,并基于Hyperledger Fabric平台搭建测试环境进行验证。结果显示,基于区块链技术的数据采集与传输系统可以有效地完成数据采集,保证数据传输与存储过程中的数据安全,数据传输率可达100%,丢包率相比传统传输系统更低。结果表明,本研究所提出的模型有效提高了数据的安全可靠性,提升了水产交易效率,更适合在实际水产交易中使用。

Preparation of MXene-based hybrids and their application in neuromorphic devices

The traditional von Neumann computing architecture has relatively-low information processing speed and high power consumption,making it difficult to meet the computing needs of artificial intelligence(AI).Neuromorphic computing systems,with massively parallel computing capability and low power consumption,have been considered as an ideal option for data storage and AI computing in the future.Memristor,as the fourth basic electronic component besides resistance,capacitance and inductance,is one of the most competitive candidates for neuromorphic computing systems benefiting from the simple structure,continuously adjustable conductivity state,ultra-low power consumption,high switching speed and compatibility with existing CMOS technology.The memristors with applying MXene-based hybrids have attracted significant attention in recent years.Here,we introduce the latest progress in the synthesis of MXene-based hybrids and summarize their potential applications in memristor devices and neuromorphological intelligence.We explore the development trend of memristors constructed by combining MXenes with other functional materials and emphatically discuss the potential mechanism of MXenes-based memristor devices.Finally,the future prospects and directions of MXene-based memristors are briefly described.

Two-photon polymerization-based 4D printing and its applications

Two-photon polymerization(TPP)is a cutting-edge micro/nanoscale three-dimensional(3D)printing technology based on the principle of two-photon absorption.TPP surpasses the diffraction limit in achieving feature sizes and excels in fabricating intricate 3D micro/nanostructures with exceptional resolution.The concept of 4D entails the fabrication of structures utilizing smart materials capable of undergoing shape,property,or functional changes in response to external stimuli over time.The integration of TPP and 4D printing introduces the possibility of producing responsive structures with micro/nanoscale accuracy,thereby enhancing the capabilities and potential applications of both technologies.This paper comprehensively reviews TPP-based 4D printing technology and its diverse applications.First,the working principles of TPP and its recent advancements are introduced.Second,the optional4D printing materials suitable for fabrication with TPP are discussed.Finally,this review paper highlights several noteworthy applications of TPP-based 4D printing,including domains such as biomedical microrobots,bioinspired microactuators,autonomous mobile microrobots,transformable devices and robots,as well as anti-counterfeiting microdevices.In conclusion,this paper provides valuable insights into the current status and future prospects of TPP-based4D printing technology,thereby serving as a guide for researchers and practitioners.