Structural-microstructural characterization and optical properties of Eu3+,Tb3+-codoped LaPO4·nH2O and LaPO4 nanorods hydrothermally synthesized with microwaves

Rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄·nH₂O single-crystal nanorods with the compositions La_0.99999-xEu_xTb_0.00001PO₄·nH₂O (x?=?0–0.03), La_0.99999-yTb_yEu_0.00001PO₄·n′H₂O (y?=?0–0.010), and La_0.99999-zTb_zEu_0.000007PO₄·n′′H₂O (z?=?0–0.012) were hydrothermally synthesized with microwaves. It is shown that the Eu³⁺,Tb³⁺ codoping does not affect the thermal stability of these nanorods, which is due to the formation of substitutional solid solutions with both Eu³⁺ and Tb³⁺ replacing La³⁺ in the crystal lattice. Moreover, it is also shown that monazite-type Eu³⁺,Tb³⁺-codoped LaPO₄ single-crystal nanorods can be obtained by calcining their rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄·(n,n′ or n′′)H₂O counterparts at moderate temperature in air, and that they are thermally stable. It is also observed that, for the same Eu³⁺,Tb³⁺-codoping content, the monazite-type Eu³⁺,Tb³⁺-codoped LaPO₄ nanorods exhibit higher photoluminescent efficiency than the rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄· (n,n′ or n′′)H₂O nanorods. Moreover, it is found that the highest photoluminescence emission corresponds to the monazite-type La_0.96999Eu_0.02Tb_0.00001PO₄ nanorods for the La_0.99999-xEu_xTb_0.00001PO₄ system. However, for those compositions energy transfer from Tb³⁺ to Eu³⁺ does not occur. In addition, for an efficient energy transfer to occur, a content of at least 1?mol% Tb³⁺ is needed in all the studied materials.     

基于Hilbert解调技术的齿轮箱故障诊断

从理论上分析了根据Hilbert解调原理进行齿轮诊断的可行性 ,并利用齿轮箱诊断实例证明了理论分析的结果。在论文结尾 ,指出了齿轮箱诊断所应注意的两个基本问题。     

Smart Dynamic Resource Allocation Model for Patient-Driven Mobile Medical Information System Using C4.5 Algorithm

A mobile medical information system (MMIS) is an integrated application (app) of traditional hospital information systems (HIS) which comprise a picture archiving and communications system (PACS), laboratory information system (LIS), pharmaceutical management information system (PMIS), radiology information system (RIS), and nursing information system (NIS). A dynamic resource allocation table is critical for optimizing the performance to the mobile system, including the doctors, nurses, or other relevant health workers. We have designed a smart dynamic resource allocation model by using the C4.5 algorithm and cumulative distribution for optimizing the weight of resource allocated for the five major attributes in a cooperation communications system. Weka is used in this study. The class of concept is the performance of the app, optimal or suboptimal. Three generations of optimization of the weight in accordance with the optimizing rate are shown.     

海洋激光雷达实验与仿真结果的对比

海洋激光雷达是探测上层海水并构建海洋立体观测网络的重要遥感设备。文中将激光雷达实验数据与MC (Monte Carlo)仿真、解析模型、原位数据进行综合对比,检验它们的匹配程度。与实验实测的激光雷达回波信号相比,MC仿真和解析模型均有很高的一致性(R^2>0.97),将原位漫射衰减系数(Kd)近似代入普通激光雷达方程也有较好的一致性(R^2>0.92)。反演得到的激光雷达衰减系数(α)表现出了相似的结果,MC仿真和解析模型具有更佳的一致性。结果表明:海洋激光雷达实验结果能与MC和解析模型的仿真结果很好地匹配。     

采用半解析蒙特卡洛技术模拟星载海洋激光雷达回波信号的软件

采用半解析蒙特卡洛方法,开发了一套星载海洋激光雷达回波信号的仿真系统。通过输入激光雷达系统参数和仿真的环境参数,该系统能够模拟具有不同光学特性的大气和海洋的激光雷达回波信号。同时该仿真系统设计了用户友好的软件界面方便用户对输入参数进行操作,并直观地看到输出结果。利用该系统进行了多种仿真,例如不同类型水体以及不同散射相函数的情况,并将仿真结果与理论的激光雷达信号做了对比,具有较高的一致性。该系统对星载海洋激光雷达探测机理的研究有一定的指导意义。     

Lignin as a Wood‐Inspired Binder Enabled Strong,Water Stable,and Biodegradable Paper for Plastic Replacement

Plastic waste has been increasingly transferred from land into the ocean and has accumulated within the food chain, causing a great threat to the environment and human health, indicating that fabricating an eco‐friendly and biodegradable replacement is urgent. Paper made of cellulose is attractive in terms of its favorable biodegradability, resource abundance, large manufacturing scale, and low material cost, but is usually hindered by its inferior stability against water and poor mechanical strength for plastic replacement. Here, inspired by the reinforcement principle of cellulose and lignin in natural wood, a strong and hydrostable cellulosic material is developed by integrating lignin into the cellulose. Lignin as a reinforced matrix is incorporated to the cellulose fiber scaffold by successive infiltration and mechanical hot‐pressing treatments. The resulting lignin‐cellulose composite exhibits an outstanding isotropic tensile strength of 200 MPa, which is significantly higher than that of conventional cellulose paper (40 MPa) and some commercial petroleum‐based plastics. Additionally, the composite demonstrates a superior wet strength of 50 MPa. Adding lignin also improves the thermostability and UV‐blocking performance of cellulose paper. The demonstrated lignin‐cellulose composite is biodegradable and eco‐friendly with both components from natural wood, which represents a promising alternative that can potentially replace the nonbiodegradable plastics.     

Poly(hydromethylsiloxane)-derived high internal phase emulsion-templated materials (polyHIPEs) containing palladium for catalytic applications

Journal of Materials Science - Cross-linking of poly(hydromethylsiloxane) (PHMS) with 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D4Vi) in water-in-oil high internal phase emulsion...     

Visualizing Thermally Activated Memristive Switching in Percolating Networks of Solution-Processed 2D Semiconductors

Memristive systems present a low-power alternative to silicon-based electronics for neuromorphic and in-memory computation. 2D materials have been increasingly explored for memristive applications due to their novel biomimetic functions, ultrathin geometry for ultimate scaling limits, and potential for fabricating large-area, flexible, and printed neuromorphic devices. While the switching mechanism in memristors based on single 2D nanosheets is similar to conventional oxide memristors, the switching mechanism in nanosheet composite films is complicated by the interplay of multiple physical processes and the inaccessibility of the active area in a two-terminal vertical geometry. Here, the authors report thermally activated memristors fabricated from percolating networks of diverse solution-processed 2D semiconductors including MoS₂, ReS₂, WS₂, and InSe. The mechanisms underlying threshold switching and negative differential resistance are elucidated by designing large-area lateral memristors that allow the direct observation of filament and dendrite formation using in situ spatially resolved optical, chemical, and thermal analyses. The high switching ratios (up to 10³) that are achieved at low fields (≈4 kV cm⁻¹) are explained by thermally assisted electrical discharge that preferentially occurs at the sharp edges of 2D nanosheets. Overall, this work establishes percolating networks of solution-processed 2D semiconductors as a platform for neuromorphic architectures.