Investigation on the Pyrazine Molecular Junction Studied by Conductance Measurement and Near Edge X-ray Absorption Fine Structure

A pyrazine molecular junction was investigated using mechanically controllable break junction (MCBJ) technique at 10 K. The conductance measurements revealed the single pyrazine molecular junctions showed two distinct conductance values of 0.27 ± 0.04 and 1.0 ± 0.2 G ₀ (2e ²/h). The conductance value of the single pyrazine molecular junction was comparable with that of the metal atomic junction. The interface between pyrazine molecule and Pt surface was investigated by near edge X-ray absorption fine structure (NEXAFS). The broadening of the π* peak in N K-edge NEXAFS spectra suggested that the pyrazine molecule connected to Pt surface via a nitrogen atom. Based on the measurements of the conductance and NEXAFS, we could propose the structural models of two distinct conductance states for the single pyrazine molecular junction.     

Reversibly Extracellular pH Controlled Cellular Uptake and Photothermal Therapy by PEGylated Mixed‐Charge Gold Nanostars

Shielding nanoparticles from nonspecific interactions with normal cells/tissues before they reach and after they leave tumors is crucial for the selective delivery of NPs into tumor cells. By utilizing the reversible protonation of weak electrolytic groups to pH changes, long‐chain amine/carboxyl‐terminated polyethylene glycol (PEG) decorated gold nanostars (GNSs) are designed, exhibiting reversible, significant, and sensitive response in cell affinity and therapeutic efficacy to the extracellular pH (pHe) gradient between normal tissues and tumors. This smart nanosystem shows good dispersity and unimpaired photothermal efficacy in complex bioenvironment at pH 6.4 and 7.4 even when their surface charge is neutral. One PEGylated mixed‐charge GNSs with certain surface composition, GNS‐N/C 4 , exhibits high cell affinity and therapeutic efficacy at pH 6.4, and low affinity and almost “zero” damage to cells at pH 7.4. Remarkably, this significant and sensitive response in cell affinity and therapeutic efficacy is reversible as local pH alternated. In vivo, GNS‐N/C 4 shows higher accumulation in tumors and improved photothermal therapeutic efficacy than pH‐insensitive GNSs. This newly developed smart nanosystem, whose cell affinity reversibly transforms in response to pHe gradient with unimpaired biostability, provides a novel effective means of tumor‐selective therapy.     

一维纳米TiO_2的可控合成及其应用的研究进展

TiO2是一种重要的多功能无机材料,一维纳米TiO2材料的可控合成是一个十分复杂的过程。由于一维纳米TiO2材料的存在形式多样(包括纳米纤维、纳米丝、纳米带、纳米棒、纳米线和纳米管等),其可控合成的工艺方法也很丰富。综述了一维纳米TiO2材料可控合成的各种方法,包括静电纺丝法、水热合成法、模板法和阳极氧化法等;分析合成过程中参数变化对所合成纳米材料结构和形貌的影响规律;回顾和总结了近年来一维纳米TiO2材料应用的研究进展;对一维纳米TiO2可控合成的研究和应用进行展望,为进一步拓展一维纳米TiO2的存在形式和应用范围提供参考。     

开放式多自由度可控机构综合实验台的研制

结合多自由度可控机构的主要研究内容、特点以及最新研究成果,研制了既能满足机械原理、机械设计等课程本科实验教学的需要,又可满足研究生机构学实验教学与科研需要的开放式综合实验台,该综合实验台不仅能实现平面机构运动简图绘制与分析等实验教学,而且还能对多自由度可控机构正、逆解运动学以及系统数字控制等问题,进行开放性实验研究,从而为进一步加强和提高学生的动手及创新能力,提供一定的实验基础。     

基于EPON的可控组播技术

以太无源光网络( EPON)作为光纤到户的理想解决方案之一,凭借其带宽优势非常适合承载组播业务.EPON可控组播技术结合EPON的特点,从安全性和可维护性考虑,提出了一套可控组播实现方案,包括组播源管理、用户认证和组播流量控制等内容,以满足组播业务可维、可控的运营管理需要.     

Fe/TiO_2纳米复合物的制备、表征及其性能

采用溶胶-凝胶结合氢气还原方法,制备了Fe与TiO2两相共存的纳米复合物。透射电子显微镜(TEM)图片显示,纳米复合物的颗粒大小为100~300nm,且具有明显的核/壳结构。X射线衍射结果表明,纳米复合物中存在a-Fe与金红石型TiO2结构,未发现其他杂相。振动样品磁强计(VSM)的测量结果表明,样品具有较高的比饱和磁化强度。研究表明,通过控制前驱物的用量,能有效改变样品的磁性。热重分析(TGA)结果表明,样品具备很好的抗氧化性。复合介电谱和磁谱表明,在测量的微波频率范围内,样品的介电损耗大于磁损耗。     

激光窄脉冲信号探测电路的设计与接收

在激光反射层析成像雷达系统中,激光脉宽越窄,系统的成像分辨率越高。而高带宽、无失真的探测接收电路设计起来较为困难。详细分析了雪崩光电二极管(Avalanche Photodiode,APD)模型及其主要性能参数,并选择了合适的探测器。然后对前置放大电路、主放大电路和可控增益放大电路进行了较为详细的分析,并设计了合适的电路结构。GHz级微弱光电信号在被接收时很容易受到外部噪声的干扰,这会导致接收波形产生畸变。采用电磁辐射屏蔽方法消除了干扰,最终无失真地探测和接收到了1 ns窄脉冲激光信号,满足了激光反射层析成像雷达系统的0.15 m成像精度要求。     

变电站自动化与可控电抗器控制器通信系统

文中提供了一种变电站自动化系统与可控电抗器控制器通信系统,主机为变电站自动化系统,从机为可控电抗器控制器触摸屏,主机与从机之间通过协议转换器连接;介绍了采用标准通信规约的重要性以及两个磁控电抗器之间的调节关系,协议转换器的配制方法.     

基于多节SIRs的新型四通带滤波器设计

提出了一种基于多节1/2波长SIRs的具有通带可控的紧凑型四通带滤波器。该滤波器由上下两个谐振器A和B组成,谐振器A由两节1/2波长SIRs中心加载一段短路枝节组成,控制第二和第三通带;谐振器B由三节1/2波长SIRs中心加载一段短路枝节组成,控制第一和第四通带,最终得到了尺寸为8.09 mm×14.12 mm(0.10λ_g×0.17λ_g)的四频带通滤波器。实验结果表明,该滤波器的通带可控并且满足低损耗的要求,4个通带的中心频率分别为2.22/3.66/5.63/7.52 GHz,插入损耗分别为0.32/0.41/1.38/0.43 dB,每个通带的回波损耗都优于20 dB,实验结果与理论分析一致。