Organic second-order nonlinear optical (NLO) materials have attracted significant attention due to their potential advantages, such as ultrafast response, wide bandwidth, low driving voltage, tunable structures, and high electro-optic (EO) coefficient (r33). In order to improve the EO activity of benzothiadiazole-based (BTD) materials and further reduce its π-π stacking effect and dipole-dipole interactions, increase the doping content of chromophores and thereby enhance the electro-optic coefficient of host-guest NLO materials, non-planar BTD-based chromophores with different modifications on the julolidine donor have been designed and synthesized. According to UV–vis-NIR spectrum, DFT calculation and EO activity analysis, introduction of nonpolar factor into the conjugated structure, such as four methyl groups into the ring-fused structure of julolidine or phenolic hydroxyl will impair the intramolecular charge transfer of chromophore. Introduction of the long flexible alkyloxy chain to the chromophore makes the guest-host film achieve high electro-optic coefficients (94 pm·V-1) at relatively high doping levels (30 wt%), exhibiting the necessity of fine-tuning the introduction site of nonpolar group.

Space gravitational wave detection refers to the method of using satellite formation or constellation to construct a large laser interferometer with interference arms of more than ten kilometers or even millions of kilometers in space to detect gravitational waves. One of the key indicators is that the ranging accuracy of laser interferometry needs to be better than 1 similar to 10 pm/Hz(1/2)@0.1 mHz similar to 1Hz. In the intersatellite laser interferometer, which was necessary to use the telescope to collimate and expand the laser beam. Due to wavefront distortion of telescope, light field transmitted to spacecraft 2 will deviate from ideal spherical wave during the intersatellite transmission. After coupling pointing jitter of telescope caused by non-conservative forces and other reasons, the phase of light field received by spacecraft 2 will change with the pointing jitter, which will eventually introduce noise in the measurement system. In order to study the error caused by the coupling of wavefront distortion and pointing jitter, the far-field phase distribution with wavefront distortion was obtained by using Kirchhoff scalar diffraction model and Zernike aberration model. After linearization, the phase and displacement noise related to pointing jitter can be obtained. Using this method, the predecessors established the noise generated by the telescope wavefront composed of different order aberrations and wavefront RMS values after far-field transmission, and analyzed the pointing direction of the telescope to reduce the coupling noise and gave how to make the optimal pointing of the telescope close to the intersatellite visual axis to assist pointing. The above research mainly focuses on analyzing the wavefront quality and aberration distribution of the outgoing pupil of the telescope, and the coupling noise can be quickly extracted by linearizing the far-field phase formula. Due to the accuracy loss in the process of linearizing the far-field phase, the numerical simulation is carried out by using the traversal method with higher accuracy and the traditional method. The simulation results show that there is 25%similar to 100% relative error in the coupled noise distribution field in the range of +/- 100 nrad. To solve this problem, this paper uses the differential evolution algorithm to extract the coupling noise, which solves the optimization problem through the process of biological evolution. It can take the jitter range centered on the static pointing of the telescope as search space, randomly select individuals within the jitter range to get the initial displacement, then judge the new individual position by comparing the difference between individuals, finally converge to the extreme value of the function to get the coupling noise. In the same case of wavefront distortion, the relative error between differential evolution method and traversal method is less than 2%. Finally, differential evolution method is used to extract coupling noise and combined with Monte Carlo simulation to give the pointing jitter index of the telescope transmitter required to achieve the gravitational wave measurement accuracy when different wavefront quality RMS values are given. The simulation results show that if the RMS value of the telescope wavefront quality is lambda/60 similar to lambda/20, for the couple noise of 10 pm/Hz(1/2)@0.1 mHz similar to 1 Hz, the pointing jitter of the transmitting telescope should be about 19 similar to 34 nrad/Hz(1/2)@0. 1 mHz similar to 1 Hz, and the pointing jitter corresponding to the noise index of 1 pm/Hz(1/2)@0.1 mHz similar to 1 Hz should be better than 2.1 similar to 7.0 nrad/Hz(1/2)@0.1 mHz similar to 1 Hz. According to the existing design parameters of the outgoing pupil wavefront RMS value of lambda/30 in LISA, Taiji and Tianqin, the pointing jitter needs to be better than 21 nrad/Hz(1/2) @0.1m Hz similar to 1 Hz and 2.2 nrad/Hz(1/2) @0.1 mHz similar to 1 Hz respectively in the measurement frequency band. This result provides a target and reference for the manufacturing and pointing control system of the telescope in the later stage.

We successfully synthesized and systematically investigated novel chromophores Y1, Y2, and Y3 with a dualdonor structure. By adjusting the electron -donating groups at different positions (C3 and C4) of thiophene, we optimized the electro-optical properties of the chromophores. We have optimized thenonlinear optical properties of the chromophores Y1 and Y2, which work with the common FTC hosts, incorporated additional electrondonating groups (DEA) at positions 3 and 4 of thiophene, respectively. At a doping concentration of 20 %, the r(33) values for FTC/APC Y1/APC and Y2/APC were 21 p.m. V-1, 56.2 p.m. V-1, and 5.8 p.m. V-1. This indicates that introducing the donor group at positions 2 and 3 of thiophene is more favorable than positions 3 and 4 (Y1 > Y2). And we successfully synthesized Y3 by replacing DEA with a julolidine moiety. At a doping concentration of 30 %, Y3/APC had the greatest r(33) of all values at 153.3 p.m. V-1. This demonstrates that introducing DEA at the 3 positions of thiophene in FTC effectively enhances the electron -donating ability, and the additional donor moiety acts as an isolated group, effectively reducing intermolecular dipole -dipole interactions. Furthermore, Y3, with julolidine as the donor group, exhibits stronger electron -donating ability, ultimately leading to enhanced macro EO activity. These findings highlight the potential application of these novel chromophores for potential applications in optoelectronic devices.

Second-order nonlinear optical (NLO) materials have become the core of photonic devices. The stability of chromophore arrangement is a key factor limiting the service life of materials. In this study, we employed a novel photo-thermal double-crosslinking networks to enhance the orientation stability of chromophore for the first time by integrating photo and thermal crosslinking techniques. Benzocyclobutene (BCB) and double bonds were introduced as crosslinked units on the polymer and chromophore, respectively. Thermal crosslinking is achieved through the Diels-Alder (D-A) reaction between BCB, while photo crosslinking is accomplished via a thiol-ene click reaction. The UV-vis spectra results demonstrate that photo-thermal double-crosslinking can provide a certain level of protection to the chromophore against decomposition at elevated temperature. Maximum electro-optic coefficient (r(33)) of BCB-based double-crosslinking networks is 23.3 p.m. V-1 (at 1.3 mu m, 25 wt%). Little difference is observed between the results of photo-thermal double-crosslinking polymer (r(33)=5.8 pm V-1, 10 wt%) and host-guest polymer (r(33)=6.7 pm V-1, 10 wt%), illustrating that the double-crosslinking reaction does not impair r(33). The analysis of the thermal simulated depolarization (TSD) curve indicates that the orientation stability of the double-crosslinked network structure (T-peak = 162 degrees C) is significantly enhanced compared to single thermal crosslinking (T-peak = 158 degrees C) or single photo crosslinking (T-peak = 144 degrees C), owing to the dual fixation of the chromophore through both photo and thermal crosslinking processes. It could be concluded that the enhancement of orientation stability does not come at the cost of the electro-optic coefficient. In a word, photo-thermal double-crosslinked second-order nonlinear materials are expected to be a promising option to research NLO optical applications.

Second-order nonlinear optical (NLO) materials have become a pivotal core for photonic devices with the development of the information globalization. The alignment stability of chromophores is the key factor affecting the services life of materials. Benzocyclobutene (BCB)-based resin, as a good encapsulating ma-terials, exhibited excellent thermal stability after cross-linking reaction. BCB remains a challenge if used directly in NLO materials due to its high curing temperature. Benzocyclobutene (BCB)-based co-polymer have been synthesized and systematically investigated for improving temporal stability of NLO materials, and bismaleimide (BMI) had been introduced as curing agent for further tuning the curing temperature of BCB in this paper. As differential scanning calorimetry (DSC) curves analysis, introduction of curing agent BMI could efficiently improve reactivity of the ring-opening and then cycloaddition of BCB group leading to lower curing temperature (the peak temperature decreased from 194 degrees C to 160 degrees C), which pre-vent the decomposition of doped chromophore during cross-linking. Thermal stimulated depolarization (TSD) results indicated that the temporal stability of NLO materials was remarkably increased due to the cross-linked network structure. (c) 2022 Elsevier B.V. All rights reserved.

Flexible sensors with high sensitivity have shown great potentials in applications such as human motion detection and wearable electronic devices. In this paper, we propose a design of flexible piezoresistive sensors with hole structures that exhibit enhanced sensitivity. The hole structures re-arrange the strain distribution under tensile loadings, and the resulting non-uniform strain distribution amplifies the overall resistive response. The underlying mechanism of the enhanced sensitivity is based on the nonlinear piezoresistive behavior of conductive polymer composites under large strains. Simulation studies accounting for the nonlinear piezoresistivity are performed to investigate the influence of the aspect ratio of an elliptical hole structure on the sensor’s sensitivity. Results show that the design of hole structures increases the piezoresistive response, and a higher sensitivity can be achieved at a smaller aspect ratio. To experimentally validate the design, sensors that are made of exfoliated graphite polymer composites with an elliptical hole of different aspect ratios are prepared and characterized. Results show that the strain sensitivity reaches 7.65 when the aspect ratio decreases to 0.1, improved by two folds compared with the control sample. To demonstrate the performance in monitoring human motions, sensors with and without hole structures are attached on the finger and the wrist to detect the bending and relaxing motion, and enhanced sensitivity is also obtained from the structure with a low aspect ratio. This work provides an effective approach to improve the sensitivity of flexible sensors that are made of piezoresistive polymer composites.

Investigating coherent acoustic vibrations in nanostructured materials provides fundamental insights into optomechanical responses and microscopic energy flow. Extensive measurements of vibrational dynamics have been performed for a wide variety of nanoparticles and nanoparticle assemblies. However, virtually all of them show that only the dilation modes are launched after laser excitations, and the acoustic bending and torsional motions, which are commonly observed in photoexcited chemical bonds, are absent. Unambiguous identification and refined characterization of these "missing" modes have been a long-standing issue. In this report, we investigated the acoustic vibrational dynamics of individual Au nanoprisms on free-standing graphene substrates using an ultrafast high-sensitivity dark-field imaging approach in four-dimensional transmission electron microscopy. Following optical excitations, we observed low-frequency multiple-mode oscillations and higher superposition amplitudes at nanoprism corners and edges on the subnanoparticle level. In combination with finite-element simulations, we determined that these vibrational modes correspond to out-of-plane bending and torsional motions, superimposed by an overall tilting effect of the nanoprisms. The launch and relaxation processes of these modes are highly pertinent to substrate effects and nanoparticle geometries. These findings contribute to the fundamental understanding about acoustic dynamics of individual nanostructures and their interaction with substrates.

The resurgence and outbreaks of mumps occur frequently in many countries worldwide in recent years, even in countries with high vaccination coverage. In this study, a descriptive and spatiotemporal clustering analysis at the township level was conducted to explore the dynamic spatiotemporal aggregation and epidemiological characteristics of mumps in Wuhan. During 2005 and 2019, there were 40 685 cases reported in Wuhan, with an average annual morbidity of 28.11 per 100 000 populations. The morbidity showed a fluctuating tendency, and peaked in 2010 and 2018. Bimodal seasonality was found, with a large peak between May and July, and a mild peak from November to January in the following year. Male students aged 5-9-year-old were the main risk group of mumps infection. Significant global spatial auto-correlation was detected except in 2007, 2009 and 2015. The spatial and temporal scan statistics indicated that the hot-spots mainly located at the western and southern areas of Wuhan with variations almost every year. Our findings could assist the public health authorities to develop and improve targeted health strategies, and allocate health resources rationally.

This paper develops a half-bridge LLC converter based on charge control and uses a new enhanced method to derive the transfer function. Charge control has become the most popular control method for the LLC converter in recent years because of its easy compensation and fast dynamic response. Its small-signal model has only one pole before the switching frequency if assuming that the input power equals the output power. But this conventional approach oversimplifies the charge control system, which will cause errors from 1/10 switching frequency to switching frequency. An enhanced small-signal method for charge-controlled LLC converter is used, which is more accurate than conventional method. The simulation results in PSIM and SIMPLIS verify its advantages.

Smart materials with multiple functions are the preferred materials for technological applications in military, medical, aerospace science and technology, and architecture. However, developing newly single-phase material coupling with multiple functions is still subjects with enormous challenge. Herein, the rare-earth elements Er3+/Yb3+ substitution of lead-free 0.7Bi(0.5)Na(0.5)TiO(3)-0.3Sr(0.7)Bi(0.2)TiO(3) (BNT-SBT) ferroelectric thin films are designed and fabricated to improve energy storage capability and upconversion luminescence. Optimized BNT-SBT thin films achieves superior discharged energy density of 52.4 J/cm(3) with high efficiency of 70.2%, as well as excellent temperature stability (RT to 150 degrees C) and fatigue endurance (10(7) circles). Additionally, the emission color of BNT-SBT thin films could be controlled through changing Yb3+ ion concentrations. More importantly, the maximum sensor sensitivity of the Er3+/Yb3+ codoped BNT-SBT thin films could reach 0.0049 K-1 at 363 K. This contribution paves a novel avenue for preparing lead-free multifunctional ferroelectric thin films, which are interested in potential application in the field of optoelectronic devices.

Electrostatic capacitors, though presenting faster rate capability and higher power density, are hindered in applications because of their low energy density. Accordingly, many efforts in electrostatic capacitors, for electronics and electrical power systems, have mainly concentrated on the development of dielectric materials with high-energy density (Ud) and charge-discharge efficiency (η) as well as good stability performances of thermal and fatigue endurance. Herein, we demonstrate that an excellent Ud (∼90 J/cm3) and high η (∼84.2%), as well as outstanding fatigue cycles (1 × 108 st), frequency stability (20-2000 Hz), and a wide temperature range (RT ∼ 160 °C), can be attained in Ba2Bi3.9Pr0.1Ti5O18 (BBPT) ferroelectric thin films via nanocrystalline engineering. It is revealed that nanocrystalline engineering of the BBPT ferroelectric thin films could be controlled via the heat-treatment temperature, which could effectively regulate the breakdown strength and polarization. The enhanced breakdown strength and polarization of the nanocrystalline engineering is further verified through the theoretical phase-field simulations along with experimental results. These results indicate that this is a feasible and scalable route to develop dielectric thin film materials with a high energy storage capability.

In this work, a well-known Au25 NCs with high purity was prepared by simple one-pot reducing method. The assynthesized Au25 NCs exhibited excellent antibacterial efficiency toward Gram-negative bacteria in a dose- and time-dependent manner, which could be used as nanoantibiotics to replace harmful antibiotics. The antibacterial assays showed that almost 100% bacteria were killed at lower concentration (100-150 mu M) within a short time (30-60 min), providing a rapid and effective killing outcome for Gram-negative bacteria. After that, antibacterial mechanism was mainly investigated at cellular level via destruction of membrane integrity, disruption of antioxidant defense system, metabolic inactivation, DNA damage, as well as at molecular level via transcriptome analysis (RNA sequencing) for the first time. RNA sequencing results showed that differentially expressed genes (DEGs) related to biosynthesis of cell wall and membrane, glycolysis and TCA cycle, oxidative phosphorylation and DNA replication and repair were significantly affected. It was concluded that synergetic effect of membrane damage, oxidative stress, DNA damage and energy metabolism eventually led to the Gram-negative bacteria growth inhibition and death.

Hollow fiber membranes have been widely used in membrane distillation (MD) applications due to their unique advantages. Their superior mechanical stabilities and large packing densities bring new possibilities for developing next-generation MD membranes for desalination and wastewater treatment. In this chapter, fundamentals of MD hollow fiber fabrication via nonsolvent phase separation (NIPS) and thermally-induced phase separation (TIPS) methods will be discussed in detail. Next, recent advances in MD hollow fiber membranes, including the development of multibore and dual-layer hollow fibers will also be summarized. This chapter may provide valuable insights in the mass production of MD hollow fiber membranes and the development of novel MD membranes for commercial applications.

Some machine learning algorithm tools, such as neural networks and Gaussian process regression, are increasingly being applied to the exploration of materials. Here, we have developed a form to use this nonlinear interpolation tool to describe properties that depend on the degrees of freedom in multi-component solids. A symmetrically adapted clustering function is used to distinguish different atomic order degrees. These features are used as the input of neural networks, Gaussian process regression and other algorithmic models, and some inherent properties of materials, such as formation energy, can be reproduced by the trained machine algorithm model. We use this technique to reproduce the expansion Hamiltonian of a synthetic cluster with multi-body interaction, and calculate the formation energy of ZrO based on first principles. The form proposed in this paper and the results shown that complex multi-body interactions can be approximated by nonlinear models involving smaller clusters. The training models used in this paper to predict energy include neural networks, Gaussian process regression, random forests, and support vectors regression, using MSE and coefficient of determination to evaluate the prediction results, and adding genetic algorithms in the feature selection process can remove some redundant features and improve the prediction efficiency and accuracy. The results show that the neural network is the best algorithm model which selected in this article, the prediction effect of support vector regression is relatively inferior.

针对车身拼接曲面光顺精度低和光顺效率低等问题,提出不同曲率半径拼接曲面的光顺方法.对于大曲率半径的拼接曲面,根据曲面与点云贴合精度调节控制顶点排序;在小曲率半径的拼接曲面中,提取拼接边线并光顺,通过裁剪的方式重新构造曲面.实际应用表明,根据光顺精度确定的不同曲率半径拼接曲面的光顺方法,能够快速光顺出高品质车身A级曲面.

如何有效地去除废水中的染料一直是材料和环境科学的热门方向.对比传统的吸附法、浓缩过滤法等,光催化降解染料技术由于其特有的环保性、简便性、安全性和无二次污染性等优点引起了更广泛的关注.众多光催化剂中,杂多酸因特殊的“笼形”结构、可“调谐”的电子性质、无毒性、富氧表面、价廉、出色的氧化还原能力等特点而具有巨大应用潜力.本文介绍了最近几年的杂多酸型光催化的研究进展,按方法将它们归类为改性法和负载法,并又细分它们为取代型杂多酸、改变反荷离子型杂多酸、有机无机改性法、硅酸盐负载法、二氧化钛负载法和石墨烯负载法.主要改进方向是提高杂多酸的水溶性、拓宽光吸收活性、增大比表面积、提高回收性等.对不同催化剂体系下的合成条件、催化机理等进行总结与分析,并展望了未来的发展趋势.

In order to solve the problem of low efficiency and easy clamping deformation in the location layout design of auto-body sheet metal,alocation layout design method of auto-body sheet metal based on NSGA-Ⅱ and RBF neural network is proposed.With the minimum deviation transfer path and the highest stability as constraints, the first three locating points are optimized by using NSGA-Ⅱ algorithm.With the support of finite element samples, BP and RBF neural network prediction models are constructed and compared, and the results of RBF neural network with higher prediction accuracy are selected as individual fitness values.The GA and PSO are used to optimize and compare the RBF neural network. The solution value of the PSO with faster convergence speed and higher accuracy is chosen as the optimal solution of the fourth location point.Using the seat-mounted beam as a model to verify the research content.The results show that the maximum clamping deformation under the optimized positioning layout is only 27% of the maximum clamping deformation before optimization.Therefore, RBF neural network can effectively predict clamping deformation of sheet metal.The research results have reference value for further research on auto-body welding fixture design and location layout of fuselagethin-walled parts.

溶胶-凝胶法具有反应条件温和、结晶度好且分散度高的优点,与旋涂法、金属掺杂法等工艺配合使用可以改变纳米材料形貌,改善产品特性,克服传统方法的局限性,使纳米材料适应面更广,品质更优良.综述了溶胶-凝胶法在零维、一维、二维、三维纳米材料合成中的研究现状及发展趋势.介绍了近年来纳米材料的合成方法、阐明了作用原理并分析了溶胶-凝胶法合成纳米材料的优越性,最后对溶胶-凝胶法发展前景进行了展望.

运用中心复合设计方法对氮化硼膨胀型防火涂料配方进行了优化,涂料主要组分为四硼酸钠、5-氨基四氮唑、磷酸硅和铝酸盐水泥(CA80).中心点处各组分的配比为:m(Na2B4O7·10H2O)=55 g,m(5-AT)-20 g,m(Si3(PO4)4)=5 g,m(CA80)=20 g,按照各种组分的相应步长正、负各取2个点,应用DesignExpert 10软件共设计出30组配方,分别进行耐火测试,得到各组分含量与耐火时间多项式模型,通过方差检验,该模型F值为8.79,p值为0.000 2,说明模型显著性强.模型预测最优配方为m(Na2B4O7·10H2O)=55.0 g,m(5-AT)-21.2 g,m(Si3(PO4)4)=4.7g,m(CA80)=18.4 g,预测耐火时间为97.2 min.对此配方配制的防火涂料进行耐火测试,平均耐火时间为96.5 min,比原中心点配方的耐火时间有所提高.

为了准确有效地对排放的工业废气进行连续自动的检测,设计了一种基于GPRS的工业废气远程监测系统.该系统以ARM9为开发平台,设计了气体传感器检测电路、废气温湿度数据采集电路、光照强度采集电路等,可实现废气的连续自动检测.把测量的结果通过GPRS网络发送到服务器上位机中,在系统中还可以实现对多个检测点的在线监测.实际实验结果表明,该系统可有效地监测到有害气体,达到实时预警的目的.