A Hollow‐Core,Magnetic, and Mesoporous Double‐Shell Nanostructure: In Situ Decomposition/Reduction Synthesis,Bioimaging, and Drug‐Delivery Properties

A novel in situ decomposition/reduction approach is developed to manu­facture hollow core, magnetic, and mesoporous double‐shell nanostructures (HMMNSs) via in situ decomposition and reduction of a β‐FeOOH nanorod core and organosilicate‐incorporated silica‐shell precursor. The formed HMMNSs are then aminated by silanization for further covalent conjugation to rhodamine B isothiocyanate (RBITC) and poly(ethylene glycol) (PEG) chains. The resultant RBITC‐grafted and PEGylated nanocomposites (HMMNS–R/Ps) have excellent blood compatibility and very low cytotoxicity towards HeLa and MCF‐7 cells, and can be taken up by cancer cells effectively in a dose‐dependent manner, as confirmed by in vitro flow cytometry, confocal luminescence imaging, and magnetic resonance imaging (MRI) studies. In vivo MRI studies coupled with Prussian blue staining of slides from different organs show that the nanocomposites preferentially accumulate in liver and spleen after intravenous injection, which suggests a potential application of the nanocomposites as MRI contrast agents. Importantly, the HMMNS–R/P nanocomposites show high loading capacity for water‐insoluble anticancer drugs (docetaxel or camptothecin) owing to the presence of a large inner cavity and enhanced surface area and pore volume. Furthermore, the drug‐loaded nanocomposites exhibit greater cytotoxicity than the corresponding free drugs. These results confirm that the HMMNS–R/P nanocomposites are promising candidates for simultaneous bioimaging and drug delivery.     

Template‐Confined Dewetting Process to Surface Nanopatterns: Fabrication,Structural Tunability,and Structure‐Related Properties

Metallic surface nanopatterns are prepared by a template‐confined dewetting process with multiple structural controllabilities. The morphology of the building blocks is homogeneous throughout the surface nanopatterns, as the dewetting process proceeds separately in each bowl. The features of the building units in the surface patterns are highly dependent on the annealing temperature. Importantly, the size and composition of the nanoparticles in the surface nanopatterns can be pre‐calculated and designed by manipulating the thickness of the evaporated metallic films. The heating temperature and composition of the building units influence the surface‐enhanced Raman scattering (SERS) and plasmonic properties, thus tuning the localized surface plasmon resonance peaks over a broad range (from visible to near infrared). The introduction of silver in the gold surface nanopatterns enhances the SERS performance dramatically. This work not only provides a powerful route to fabricate surface nanopatterns, but also supplies a platform to study the mechanism of the complicated dewetting processes of metals.     

Effective PEGylation of Iron Oxide Nanoparticles for High Performance In Vivo Cancer Imaging

A practical and effective strategy for synthesizing PEGylated superparamagnetic iron oxide nanoparticles (SPIONs) is established. In this strategy, poly(acrylic acid) (PAA) is combined with SPIONs via multiple coordination between the carboxylic groups of PAA and SPIONs, which introduces abundant carboxylic groups, then, α,ω‐diamino PEG is linked to SPIONs via the amidation of the carboxylic groups. The synthesized PEGylated SPIONs exhibit no cytotoxicity and high resistance to phagocytosis by macrophages in vitro as well as low uptake by the liver and spleen in vivo, which makes the SPIONs highly efficient in tumor imaging by magnetic resonance imaging (MRI) at a relatively low dose of SPIONs. These outstanding properties are largely due to the significant shielding effect of the dense PEG coating as well as the net neutral surface of the PEGylated SPIONs in physiological conditions. In summary, the PEGylated SPIONs prepared by this strategy exhibit great application potential in tumor imaging as MRI contrast agents targeting through enhanced permeability and retention (EPR) effect.     

分子印迹膜SPR传感器检测氯磺隆的方法

研究使用了中国科学院电子学研究所自行研制的高灵敏度单通道SPR分析仪和进样装置,仪器为棱镜耦合型SPR传感器结构,其检测角度范围是40°～70°,折射率检测范围为1.04～1.47,谐振角的精度在0.001°。适用于SPR分析仪的分子印迹芯片采用PVC-MIP共聚膜法制备,SPR角度扫描结果表明,200nm以下厚度芯片具有较好的SPR吸收特性。以氯磺隆为模板的分子印迹膜与不加氯磺隆的分子印迹膜对比实验发现前者具有特异性结合的能力。实验对浓度0.1,0.2,0.5和1μg/mL的氯磺隆进行了SPR定点检测,这四种浓度氯磺隆的折射率响应信号满足线性关系,相关系数R=0.996 4。实验中对低浓度的氯磺隆进行反复检测,检测到50ng/mL的氯磺隆,满足农残检测的要求。     

微波组件设计中的腔体效应

微波有源模块因为腔体的原因造成自激和传输参数的恶化一直是微波电路设计的难点之一.目前没有完整的理论来支持微波有源电路模块的腔体设计.本文从理论上分析了以微带线作为主要微波传输载体的微波组件的腔体效应,借助电磁场仿真工具HFSS对装有微带电路的微波组件进行了仿真.根据仿真结果设计X波段微波组件,并对S参数进行了测试,测试...     

Influence of the surface roughness on the properties of Au films measured by surface plasmon resonance and X-ray reflectometry

Thickness and refractive index of Au films thermally evaporated onto glass substrates and with an underlayer of Cr are determined from surface plasmon resonance. The results for the thickness are found to agree very well with those from X-ray reflectivity when a simple model of layers with flat interfaces is used. Plasmon propagation along thin films is influenced by radiative damping due to scattering from surface roughness. To study this influence the surface roughness of the glass substrate, Cr an Au layers are measured by X-ray reflectometry and the results used to introduce three intermediate layers with effective refractive indices and thicknesses corresponding to the roughness. Then Fresnel's equations are used to fit the reflectivity and to deduce the layer properties. It is found that the roughness affects to a great extent the optical parameters of the Au films even when it is smaller than 1 nm. In particular, the absolute value of real part of the dielectric constant decreases while its imaginary part increases when those effects are not taken into account.     

Ferromagnetism in Ga0.90Mn0.10As1 − yPy: From the metallic to the impurity band conduction regime

The magnetic properties of low temperature MBE grown Ga_0.90Mn_0.10As_1 − yP_y films with 0 < y < 0.20 have been studied as a function of the phosphorous content. The films are ferromagnetic for all phosphorous compositions. For y < 0.15 the conductivity type is metallic but above y > 0.15 it changes to impurity band conduction (IBC). In the IBC regime the main magnetic properties are profoundly modified: the saturation magnetization decreases from typically 50 emu/cm³ to 35 emu/cm³, the critical temperature drops sharply from 130 K to 45 K and the uniaxial magnetic anisotropy spectroscopy is strongly reduced.     

CO and NH3 sensor properties and paramagnetic centers of nanocrystalline SnO2 modified by Pd and Ru

Nanocrystalline gas sensitive materials based on tin dioxide modified by Pd or Ru were synthesized via wet chemical route. The interaction of modified materials with CO and ammonia was studied by in situ DC-conductivity measurements and ex situ EPR spectroscopy. Modification by Pd yields the material highly sensitive to CO in low temperature region, while Ru-modified SnO₂ is very sensitive to NH₃ at raised temperature. We have detected that O₂⁻ and OH radicals are the main spin centers in unmodified nanocrystalline tin dioxide. The modification of tin dioxide by Pd and Ru is accompanied by formation of new spin centers in the samples: Pd^+ 3 and Ru^+ 3. The concentration of these paramagnetic species on the materials interacting with CO and ammonia gases decreased because of their transition to the diamagnetic state Pd^+ 2, Pd⁰ and Ru^+ 4, respectively.     

大跨度钢结构楼盖的消能减振设计

文章介绍了某火车站高架候车大厅大跨度钢结构楼盖的消能减震设计.在楼盖指定钢梁的跨中安置TMD-粘滞流体阻尼器消能减振装置,消能减振装置包括TMD和粘滞阻尼器两部分,每个TMD由一个质量块和4个弹簧减振器组成,粘滞阻尼器选用无刚度的速度线性相关型阻尼器.分析计算表明,安装减振装置后,有效地削减了该楼盖的共振响应,所有工况...     

3．0T磁共振扩散加权成像对肺部良恶性肿块的诊断价值

目的探讨3．0T磁共振扩散加权成像（DWI）对肺部良、恶性肿块的诊断价值。方法56例经CT扫描和手术证实的周围型肺部肿块行MRI常规和DWI扫描（b=0、300、500、700、900s·mm^-2）,并得到各b值的表观扩散系数（ADC）值,采用5分制评分法对2种参照物（胸髓和胸壁肌肉）DWI的病灶信号强度进行评分,采用t检验和ROC曲线进行对比并评价DWI诊断肺部良恶性病灶的敏感性、特异性,同时对各b值对应的ADC值进行量化分析。结果以肌肉为参照时,肺癌和良性病变的DWI信号强度评分分别为（3．97±1．21）、（2．55±1．46）分,两者比较差异有统计学意义（P=0．00036）;病灶的信号强度≥3判为癌症,其诊断敏感性为86．8％,特异性为66．7％。以胸髓为参照时,肺癌和良性病变的DWI信号强度评分分别为（4．23±0．99）、（2．94±1．43）分,两者比较差异有统计学意义（P=0．00025）;病灶的信号强度≥3判为癌症,其诊断敏感性为94．7％和特异性为50．0％。以肌肉和胸髓为参照的ROC曲线下面积分别为0．768、0．729,两者比较差异无统计学意义（P〉0．05）。从2种评分方式的诊断能力来看,以肌肉为参照的评分方式略优于以胸髓为参照。各b值不同病理类型肺癌与肺部炎症ADC值差异均无统计学意义。结论3．0T磁共振行肺部DWI成像,DWI的信号强度有助于良恶性病变的鉴别诊断,以肌肉为参照具有较高的敏感性和特异性,肺部ADC值不能作为定量诊断标准。DWI可能成为肺部良恶性肿块鉴别诊断的一种新的辅助技术手段。