A novel photoelectrochemical (PEC) biosensor was proposed by preparing Au NP/MXene–BiOCl Moiré superlattice nanosheets as the probes. Upon irradiation with visible light, the probe exhibited excellent electrical conductivity as well as high photoelectric conversion efficiency. Benefitting from the excellent PEC property of the hybrid probe, sensitive and accurate detection of protein kinase activity was demonstrated with a limit of detection of 0.0029 U mL−1. This study verifies the great PEC potential of MXene hybrid nanomaterials.

Development of high-performance fluorescent materials is crucial for fluorescence imaging technology. Herein, well-defined fluorescent star poly-N-isopropylacrylamide (Flu-PNIPAM) was prepared via reversible additionfragmentation chain transfer (RAFT) polymerization in a continuous-flow microreactor. A tetrafunctional RAFT agent and the functional monomer fluorescein undecylenoyl (Flu-UE) were synthesized, and then pumped into a microreactor with NIPAM monomer together for RAFT polymerization. The microreactor process parameters for the RAFT polymerization were optimized to obtain well-defined Flu-PNIPAM. The NIPAM and FluUE units endow Flu-PNIPAM with temperature and pH responsiveness, respectively. Transmission electron microscopy and dynamic light scattering analyses revealed that Flu-PNIPAM self-assembled into nanoparticles with uniform size in an aqueous solution at 37 degrees C. Moreover, Flu-PNIPAM exhibited good fluorescence and biocompatibility, rendering it highly promising for cell imaging.

In this study, we report a distinct phase tailorable solution cast polyvinylidene fluoride (PVDF)-based composite films with transition metal carbides and nitride (MXene) fillers achieved by supercooling of the PVDF melt and their dielectric energy storage performance. An unusual thermal treatment temperature higher than the widely used Tm was used to realize supercooling. Phase structure analysis by using attenuated total reflection infrared spectroscopy (ATR-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) indicated that a small amount of added MXene induced a considerable fraction (76%) of beta-phase PVDF and a 10-fold increase in dielectric permittivity (100 Hz) due to filler induced crystallization and super confinement effect when a processing temperature around melting temperature (Tm) is used. Surprisingly, although chain packing and crystallization of the macromolecules occur below Tm, a higher processing temperature even induced a double polar (beta + gamma) phase PVDF as a consequence of supercooling and increased crystallization rate. Interestingly, a nonpolar alpha phase dominant structure was formed again when the processing temperature was 190 degrees C. These findings indicate that the moderate fast crystallization facilitates the polar phase formation, which may be attributed to their higher intermolecular dipole interaction within the geometry confined by the 2D fillers. The results imply a simple way to tailor PVDF phase structure, offering insights into polymer polymorph formation.Highlights A phase tailorable PVDF-based composite film with MXene fillers was fabricated. Phase structure of MXene/PVDF film was analyzed via ATR-IR, XRD, and DSC. MXene induced an increase in dielectric permittivity and high beta-phase in PVDF. Thermal treatment at various temperatures tailored the phase structure of PVDF.

Solid-liquid phase change materials (PCMs) have the advantages of easy adjustment of the phase transition temperature, high heat enthalpy, and small volume change, which endow them with great application potential in thermal management. However, problems such as low thermal conductivity, inherent stiffness, and liquid flow of solid-liquid PCMs limit their functional applications. Herein, high-enthalpy composite PCMs supported by polymer aerogel are reported, which can prevent long-range crystallization and provide shape stability before and after phase transition. In this work, aramid nanofiber (ANF) aerogel was used as the carrier, polyethylene glycol (PEG) was used as the PCMs, and the encapsulation of PEG in aerogel was realized by vacuum impregnation. The resulting polymer aerogel-based composite PCMs exhibit a large phase change enthalpy (175.1 J/g) at a PEG content of 95.4 wt%, accompanied by a good thermal conductivity of 1.03 W/m center dot k. Benefiting from the excellent phase change thermal management performance and temperature adjustability, the composite has promising applications in high-end electronic equipment, heat dissipation and pipeline insulation.

Assessment is an essential part of the rehabilitation process for post-stroke patients, while due to the low accuracy and long duration of traditional rehabilitation assessment methods, as well as the fact that the assessment mainly relies on the subjective judgment of doctors, there is a lack of efficient, high-precision and objective intelligent assessment methods. Facing the above needs, this study developed a lightweight human motor function dynamic analysis system based on the Fugl-Meyer assessment scale to evaluate the different rehabilitation stages of post-stroke patients. We use a cell phone as the lightweight device to dynamically track the changes of patients’ motion in multiple sensitive motion paradigms and identified motion vector centroids by sliding window convolution to perform normalization of temporal features. Based on this, we process temporal information by simulating RGB image features skillfully and use a multimodal decision fusion model consisting of a convolutional neural network (CNN) and a long and short-term memory (LSTM) network to achieve quantitative scoring of patients’ rehabilitation degrees. Experimentally verified by 12 participants from the China Rehabilitation Research Center (CRRC), the system proved to be effective in assessing the rehabilitation level of stroke patients, and significantly improved the efficiency and precision of the existing assessment methods.

Motor synergy is considered as a motor control strategy deployed by the central nervous system (CNS), and it can be altered due to ageing, disease and injury. A timely assessment and analysis of altered motor synergy patterns will be helpful for the motor rehabilitation process. However, current research has mainly focused on the implementation of automated assessment scales. While the mechanism of the motor synergy structure alteration is not well understood yet. In this study, we proposed an approach to the analysis of altered human motor synergistic structures. By collecting and preprocessing the 3-dimensional motion data from 30 participants (including 15 stroke patients and 15 healthy individuals), synergistic structure features were extracted. We obtain the spatiotemporal vectors of motion by the nonnegative matrix factorization. These vectors were clustered using K-means and matched with the scalar product. The similarity and specificity clustering pairs were obtained through Kuhn-Munkres Algorithm. The above results revealed that the structure of human motor synergy was greatly altered after stroke, and some new synergistic patterns with commonalities emerged during patients' movements. This study presents a new method to identify specific patterns of motor synergy arising from disease-altered biomechanics and central nervous system, providing new targeted protocols for rehabilitation assessment.

Novel thermoplastic fluorinated polyacrylate films possessing excellent mechanical performance are prepared by emulsion polymerization latex using adjustable amphiphilic star macro-reversible addition-fragmentation chain-transfer (macro-RAFT) agent as surfactants in this work. First, star macro-RAFT agent equipped with six amphiphilic arms is synthesized via two-step RAFT polymerization of acrylic acid (AA) and 2,2,2-trifluoroethyl acrylate (TFEA) in the presence of hexa-functional RAFT agents. The surface activities of the as-synthesized amphiphilic star macro-RAFT agents in aqueous solutions are studied. Subsequently, various fluorinated polyacrylate latexes are obtained by conducting emulsion polymerization of 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) and butyl acrylate (BA) using the amphiphilic star macro-RAFT agents as both RAFT agents and surfactants. The latex particle morphologies are studied by transmission electron microscope (TEM) and particle size is measured by dynamic light scattering (DLS). The effects of PAA segment length, HFBA/BA mole ratio, and TFEA segment length on the surface morphologies of the fluorinated polyacrylate films are illustrated by investigating the surface properties using water contact angle test and atomic force microscopy (AFM). Finally, the elastomeric films obtained by directly casting the prepared fluorinated polyacrylate latexes show excellent comprehensive properties such as tensile strength over 4 MPa, elongation at break approximate to 700%, permanent deformation below 25%. Water absorption test is also provided as a reference.

Poly(3,4-ethylenedioxythiophene): poly (styrenesulfonate), namely, PEDOT: PSS or PP as one branch of conductive polymers (CPs) which can effectively transform electrical energy to mechanical energy, has been applied in many fields including electrochemical ionic soft actuators (EISAs), in terms of its high conductivity (0.1 similar to 3000 S/cm(-1)), small band gap (1.6-1.7 eV), low redox potential, good durability, good chemical and thermal stability, excellent mechanical properties, and adjustability. Furthermore, when PP as active binders are mixed with nanomaterials, they can not only be used to disperse nanomaterials and prevent their aggregation, but also efficiently enhance mutual conduction, specific surface aera, and redox activity. Here, an extensive review on PP-based EISAs including PP-carbon nanomaterials and PP-non carbon nanomaterials is reported, highlighting their structure and fabrication, electrochemical properties, actuation performance, mechanical properties, and applications. The great synergy between PP and advanced nanomaterials with diverse fabricating principles that provide sufficient ions storage space, ordered charges pathways, stiffness for high actuation displacement, fast responds and excellent flexibility is emphasized. Furthermore, the novel applications of EISAs toward smart devices and soft robots are also summarized. Finally, the review also proposed the current challenges and further prospect of EISAs.

微塑料是指粒径小于5mm的塑料,包括碎片、纤维、颗粒、发泡等不同形貌类型.作为一种新型环境污染物,微塑料污染已成为全球性的环境问题.微塑料进入农田后,对土壤理化性质、微生物群落、土壤动植物生长等均产生不利影响,损害土壤健康,影响农业生产和农产品质量.开展微塑料研究,构建准确的分析方法是重要基础和前提.该文对农田土壤中微塑料的测试方法进行比较研究,对比分析目检法、扫描电镜/能谱法、热裂解气质联用和显微-傅里叶变换红外光谱法在研究微塑料中的优缺点.结果表明,显微-傅里叶变换红外光谱法不仅能够对微塑料颜色、尺寸大小进行形貌表征,而且能够对其组成成分进行谱图鉴别,是土壤微塑料分析鉴别的理想方法.基于显微-傅里叶变换红外光谱法,分析微塑料在新疆农田土壤中的分布及组成特征,微塑料形状主要为薄膜状(35.2％),颗粒状(27.8％)和纤维状(22.5％);粒径<200μm(44.2％),200～500μm(32.5％),500～1000μm(12.8％),1000～5000μm(10.5％);材质以聚乙烯(60.2％)、聚丙烯(18.3％)、聚氯乙烯(8.6％)为主.

There are a lot of principles for sound transmission in the pipeline for whether sound transmission structure or noise reduction structure. Even in ultrasonic testing, there is a large number of principles for using pipeline sound transmission. Based on the sound propagation model and the boundary conditions of pipe wall sound absorption, the sound propagation equation for pipe wall sound absorption is given by establishing mathematical model and solving mathematical equation in this paper. When the distribution of sound field along the cross-section of the pipe (outlet) is ignored, the transmission efficiency of sound with different frequencies can be calculated or the sound absorption efficiency can be calculated. The analytical solution of the sound transmission equation in the pipeline has great theoretical significance and practical value for guiding the structural design of sound transmission and noise reduction, improving the calculation efficiency and verifying the numerical analysis results.

Sensitive detection of protein kinase activity is critical for the relevant disease diagnosis and drug discovery. Here, a label-free photoelectrochemical (PEC) biosensor was developed for protein kinase activity detection and its inhibitor screening. Kemptide was immobilized on gold nanoparticles (Au NPs)-decorated Ti3C2 MXenes (Au NPs/MXenes). After catalyzed by protein kinase A (PKA), the UiO-66-NH2 probes were modified on the phosphorylated kemptide due to the interaction between the phosphate groups and Zr4+ in UiO-66-NH2. Following irradiation by visible light, photogenerated electrons from the UiO-66-NH2 framework structure were promptly transferred to the Au NPs/MXenes, ultimately generating photocurrent for detection of PKA. The photocurrent signal was amplified for three reasons. Firstly, Au NPs/MXenes acted as a highly efficient biocompatible immobilization matrix for kemptide. Secondly, large photocurrent was produced by the light-harvesting UiO-66-NH2 probes. Thirdly, Au NPs/MXenes served as electron transfer bridges, accelerating the transfer of electrons from the UiO-66-NH2 structure to the electrode surface and preventing the electron-hole recombination. Therefore, the PEC biosensor exhibited high sensitivity toward the PKA with a low detection limit of 0.0026 U/mL. Furthermore, the assay was utilized to screen inhibitors successfully, indicating its promising potential in other protein kinase detection and clinical diagnosis.

A three-dimensional porous SERS powder material, Ag nanoparticles-engineered-silica aerogel, was developed. Utilizing an in situ chemical reduction strategy, Ag nanoparticles were densely assembled on porous aerogel structures, thus forming three-dimensional "hot spots" distribution with intrinsic large specific surface area and high porosity. These features can effectively enrich the analytes on the metal surface and provide huge near field enhancement. Highly sensitive and homogeneous SERS detections were achieved not only on the conventional liquid analytes but also on gas with the enhancement factor up to ∼108 and relative standard deviation as small as ∼13%. Robust calibration curves were obtained from the SERS data, which demonstrates the potential for the quantification analysis. Moreover, the powder shows extraordinary SERS stability than the conventional Ag nanostructures, which makes long term storage and convenient usage feasible. With all of these advantages, the porous SERS powder material can be extended to on-site SERS "nose" applications such as liquid and gas detections for chemical analysis, environmental monitoring, and anti-terrorism.

A new low-cost high-permittivity flexible nanocomposite consisting of a polyvinylidene fluoride (PVDF) matrix and fullerene-like tungsten disulfide nanoparticle (IF-WS2 NP) filler was fabricated via a simple solution route. A comprehensive investigation by X-ray diffraction, attenuated total reflection-infrared spectroscopy, and differential scanning calorimetry (DSC) showed that 0.5–1 vol% of IF-WS2 induced a nonpolar α-phase to coexisting triple-phase transition in PVDF, whereas a slightly higher loading of 2 vol% induced pure double-polar β- and γ-phases. These results indicate that the structure and properties of the fabricated nanocomposite are easily tailorable. DSC during heating and cooling cycles and morphology observations further indicated that a polar phase was induced by the nucleation effect of the IF-WS2 NPs and electrostatic interactions. As a consequence of the multiphase coexistence and structure homogeneity, nanocomposites with approximately 0.5–1 vol% of IF-WS2 NPs showed enhanced dielectric and energy-storage performance as well as enhanced tensile strength and elongation. The new phase-tailorable nanocomposites with balanced properties are promising for applications as energy-storage capacitors, piezoelectric sensors, and other flexible multifunctional components. The results of this study will serve to deepen the understanding of the polymer polymorph and provide directions on new routes for fabrication of smart materials.

Protein phosphorylation regulated by protein kinases, as well as their dephosphorylation, is one of the most common post-translational modifications, and plays important roles in physiological activities, such as intracellular signal communications, gene transcription, cell proliferation and apoptosis. Over-expression of protein kinases is closely associated with various diseases. Consequently, accurate detection of protein kinases activities and their relevant inhibitors screening is critically important, not only to the biochemical research, but also to the clinical diagnosis and therapy. Nanomaterials, taking advantage of large surface areas, as well as excellent electrical, catalytic, magnetic and optical properties, have been utilized as target concentrators, recognition components, signal transducer or amplification elements in protein kinase related assays. This review summarizes the recent representative works to highlight the applications of nanomaterials in different biosensor technologies for protein kinases activities detection and their inhibitors screening. First, different nanomaterials developed for phosphoprotein/phosphopeptide enrichment and phosphate recognition are introduced. Next, representative works are selected that mainly focus on the utilization of nanomaterials as signal transducer or amplification elements in various protein kinases sensing platforms, such as electrochemical, colorimetric, fluorescent, and mass spectroscopy-based approaches. Finally, the major challenges and perspectives of nanomaterials being applied in protein kinases related assays are discussed.

In this study, high Curie Temperature (T-c) perovskite ceramics of optimized composition 0.55(0.1BiYbO(3)-0.9PbTiO(3))-0.45PbZrO(3) with unique double orthorhombic main phases were prepared by a modified sol-gel method. Compared to the usual solid-state prepared sample, the sol-gel derived sample has a 1.6 times higher d(33) of 325 pC/N, a 2.4 times higher remnant polarization, and a much better high temperature stability with similar depolarization temperature (T-d) and T-c. Comprehensive analysis of the xerogel prepared over a wide calcination temperature (T-cal) range of 300-1000 degrees C revealed that perovskite structure appeared at only 400 degrees C and it became the main phase above 500 degrees C. Comparison of XRD refinement results showed that calcination and sintering induced subtle and continuous phase transition, namely, the 400-900 degrees C calcined powders with coexisted tetragonal (P4mm) and orthorhombic (Pbam) phase changed to a rather stable double orthorhombic (Pmmm and Pbam) main phase in all the differently sintered ceramics, as similar to the 1000 degrees C calcined powders. The stable phase coexistence well explains the enhanced performance. The results also demonstrate that optimized sol-gel processing can provide high Tc ceramics with desirable multi-phase structure and significantly enhanced performance at a lower temperature. (C) 2019 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.

With the explosive growth of flexible electronics, the prototype piezoelectric polymer poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] has gained tremendous attention due to potential applications in flexible sensors, energy harvesters, and new smart devices. However, full realization of these applications is still challenging due to the lack of high quality films with strong piezoelectricity, which requires tailored molecular organization. Here we report unique 'full nanowire' P(VDF-TrFE) films with substantially enhanced bidirectional performance by a simple self-assembly via selective vapor annealing. Structural analysis showed that the solvent molecules significantly enhanced the copolymer chain mobility, giving highly ordered nanowires, whose quantity increased with time and finally formed a full flat-on lamellar nanowire array with backbones highly aligned along the film plane, leading to high lateral piezoelectricity as revealed by vector piezoresponse force microscopy and confirmed by electrical measurements. Surprisingly, the nanowire films also showed a much higher vertical piezoelectric coefficient (-35.2 pC N-1 directly measured by using a Berlincourt meter) than that of usually crystallized films owing to simultaneously enhanced molecular order and dipole switching ability. The scalability of the new method might boost industrial applications, and the findings may provide hints on new routes to nanostructured polymers with novel functionalities and deepen our understanding of the self-assembly of random copolymers.

利用生物质单体醇和酸为原料,采用熔融缩聚的方法制备了不同异山梨醇(IS)含量(占总二醇的摩尔含量)的一系列生物基共聚酯(BCPE).以IS、1,4-丁二醇(BDO)、癸二酸(SeA)和衣康酸(IA)合成四元体系共聚酯BCPE-Ⅰ,在四元体系的合成的过程中引入单体1,3-丙二醇(PDO)合成五元体系BCPE-Ⅱ.本工作研究了IS的含量对BCPE-I和BCPE-Ⅱ体系的分子量及其分布、分子结构、结晶性能以及力学性能的影响.差式扫描量热(DSC)结果表明在BCPE-Ⅰ分子链中引入IS结构单元可以破坏聚合物分子链的有序性,对BCPE-Ⅰ的结晶有一定的抑制作用.通过引入第五种单体PDO形成聚酯BCPE-Ⅱ,调整IS的含量可以在破坏聚合物分子链规整性抑制其结晶性能的同时,使聚合物达到一定的分子量,可以实现聚合物由半结晶的塑料转变为柔软的弹性体.

本文采用薄片法原理,设计出已获专利授权的新型扫描电镜载样装置,并将其安装在扫描电镜中,对分散为薄层的混合纳米材料进行元素分布测试.应用热场电镜能谱(SDD)系统具有的稳定可变束流、高计数率等优点,在相同的实验条件下与冷场扫描电镜能谱(Si(Li))系统进行对比.实验结果说明:较传统方法,采用新方法提升了电镜能谱的空间分辨率,而且热场优于冷场的水平,元素分布的识别效果得到显著提高,热场电镜能谱的分析领域得到完善.该方法也为应用热场电镜能谱对纳米材料进行成分分析提供了新的思路.