General Strategy for Synthesis of Ordered Pt3M Intermetallics with Ultrasmall Particle Size

Controllable synthesis of atomically ordered intermetallic nanoparticles (NPs) is crucial to obtain superior electrocatalytic performance for fuel cell reactions, but still remains arduous. Herein, we demonstrate a novel and general hydrogel‐freeze drying strategy for the synthesis of reduced graphene oxide (rGO) supported Pt₃M (M=Mn, Cr, Fe, Co, etc.) intermetallic NPs (Pt₃M/rGO‐HF) with ultrasmall particle size (about 3 nm) and dramatic monodispersity. The formation of hydrogel prevents the aggregation of graphene oxide and significantly promotes their excellent dispersion, while a freeze‐drying can retain the hydrogel derived three‐dimensionally (3D) porous structure and immobilize the metal precursors with defined atomic ratio on GO support during solvent sublimation, which is not afforded by traditional oven drying. The subsequent annealing process produces rGO supported ultrasmall ordered Pt₃M intermetallic NPs (≈3 nm) due to confinement effect of 3D porous structure. Such Pt₃M intermetallic NPs exhibit the smallest particle size among the reported ordered Pt‐based intermetallic catalysts. A detailed study of the synthesis of ordered intermetallic Pt₃Mn/rGO catalyst is provided as an example of a generally applicable method. This study provides an economical and scalable route for the controlled synthesis of Pt‐based intermetallic catalysts, which can pave a way for the commercialization of fuel cell technologies.     

Solvent‐Free Self‐Assembly for Scalable Preparation of Highly Crystalline Mesoporous Metal Oxides

Mesoporous metal oxides (MMOs) have been demonstrated great potential in various applications. Up to now, the direct synthesis of MMOs is still limited to the solvent induced inorganic‐organic self‐assembly process. Here, we develop a facile, general, and high throughput solvent‐free self‐assembly strategy to synthesize a series of MMOs including single‐component MMOs and multi‐component MMOs (e.g., doped MMOs, composite MMOs, and polymetallic oxide) with high crystallinity and remarkable porous properties by grinding and heating raw materials. Compared with the traditional solution self‐assembly process, the avoidance of solvents in this method not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. We believe the presented approach will pave a new avenue for scalable production of advanced mesoporous materials for various applications.     

Recent Advances in Divergent Synthetic Strategies for Indole-Based Natural Product Libraries

Considering the potential bioactivities of natural product and natural product-like compounds with highly complex and diverse structures, the screening of collections and small-molecule libraries for high-throughput screening (HTS) and high-content screening (HCS) has emerged as a powerful tool in the development of novel therapeutic agents. Herein, we review the recent advances in divergent synthetic approaches such as complexity-to-diversity (Ctd) and biomimetic strategies for the generation of structurally complex and diverse indole-based natural product and natural product-like small-molecule libraries.     

增强自主创新能力 支撑企业战略转型

本文首先介绍了中国电信集团和各省公司在技术创新方面所做的工作及目前取得的初步进展和成绩.然后进一步分析了中国电信技术创新面临的形势和要求,最后提出了中国电信技术创新的目标和战略.     

IMS的发展与展望

本文分析了近期IMS(IP multimedia subsystem,IP多媒体子系统)发展的主要驱动因素,总结了IMS技术标准和网络部署的发展现状,通过综合归纳,指出了IMS近期发展的方向以及运营商部署IMS网络必须考虑的业务和技术问题.     

基于变行频采样的红外图像重建技术研究

为了使一些单元或线列探测器获得的扫描数据含有相应的空间信息,进而提高获得红外热像的分辨率,提出了圆锥扫描机制下基于变行频采样机理的红外图像完整重建策略。结合圆锥扫描机制下变行频采样的运动特性、优点和采样机理,通过补场搜索重建了导弹架上捕获模式下的完整红外图像。利用空间基准参量,通过计算机仿真给出了变行频采样示意图和重建图像。仿真过程表明这种技术能够有效避免因导弹自旋造成的单场边缘行采样稀疏的缺点,而获得较高分辨率的红外图像。这种技术在投入相对较低的情况下,为目标检测和跟踪研究提供可靠的数据源,具有很好的应用前景。     

面向目标跟踪的传感器网络布局优化及保护策略

本文以目标跟踪为应用背景,改进了已有传感器感知模型和虚拟力方法,提出了一种新的传感器网络布局优化策略,该策略首先计算传感器与目标、热点区域、障碍物和其他传感器之间的虚拟力,为各传感器寻找受力平衡点,并将其作为该传感器的新位置,从而优化网络布局优化．实验证明,该策略可有效改善传感器网络覆盖率和目标探测概率．同时,本文根据各传感器获取的信息量,提出了涉及目标的传感器网络节点重要性排序算法,以及根据节点重要性进行传感器网络保护的策略。     

P2P中一种使用缓存和测量的节点选择模式

针对非结构化P2P中服务节点的选择问题,利用缓存和测量技术,提出了测量次数可变的选择模式(VM)和测量次数不变的选择模式(FM).同时,给出了4种缓存更新策略:随机丢弃,最大延迟丢弃,最早时间丢弃和最少使用丢弃.仿真实验的结果表明,FM优于VM,最大延迟丢弃和最少使用丢弃策略获得了较好的性能,同时,该选择模式对节点加入和离开有较好的鲁棒性,且并发测量可以降低节点选择的时延.     

移动自组网电力及负荷感知的构造最小连通支配集算法

在移动自组网络MANET(Mobile Ad-hoc Networks)中,移动节点之间的通信是多跳(Multi-hop)的,即需要网络中其他节点的参与得以进行,因此,节点之间的通信路径会因为节点的电力耗竭或节点的移动而中断.本文提出了根据移动节点当前电力及通信负荷来选择支配节点的最小连通支配集CDS(Connected Dominating Set)构造算法,这种算法可以减小由移动节点电力耗竭所致的通信路径失效的概率,也可以减少数据包通过各移动节点的延误时间,对设计MANET的高效稳定的路由策略有着重要的应用价值.     

新形势下中国半导体设备的发展对策

随着半导体生产热点全球性地向中国转移,国内的半导体设备行业面临着空前的巨大机会和前所未有的严峻挑战。在全面深入分析半导体设备特性以及行业发展特点的基础上,指出核心技术是产品性能和成本即市场生命力的决定性因素。针对当前国内半导体设备开发中普遍存在的偏差与误区,提出了努力促进企业自身对核心技术全面深入的掌握,不断增强其自主持续创新能力的半导体设备发展对策。以全自动引线键合机开发和市场的具体详细实例印证这一论断。