Multifunctional core–shell nanoparticles: superparamagnetic,mesoporous, and thermosensitive

Multifunctional core–shell composite nanoparticles (NPs) have been developed by the combination of three functionalities into one entity, which is composed of a single Fe₃O₄ NP as the magnetic core, mesoporous silica (mSiO₂) with cavities as the sandwiched layer, and thermosensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) copolymer as the outer shell. The mSiO₂-coated Fe₃O₄ NPs (Fe₃O₄@mSiO₂) are monodisperse and the particle sizes were varied from 25 to 95 nm by precisely controlling the thickness of mSiO₂-coating layer. The P(NIPAAm-co-AAm) were then grown onto surface-initiator-modified Fe₃O₄@mSiO₂ NPs through free radical polymerization. These core–shell composite NPs (designated as Fe₃O₄@mSiO₂@P(NIPAAm-co-AAm)) were found to be superparamagnetic with high r ₂ relaxivity. To manipulate the phase transition behavior of these thermosensitive polymer-coated NPs for future in vivo applications, the characteristic lower critical solution temperature (LCST) was subtly tuned by adjusting the composition of the monomers to be around the human body temperature (i.e. 37 °C), from ca. 34 to ca. 42 °C. The thermal response of the core–shell composite NPs to the external magnetic field was also demonstrated. Owing to their multiple functionality characteristics, these porous superparamagnetic and thermosensitive NPs may prove valuable for simultaneous magnetic resonance imaging (MRI), temperature-controlled drug release, and temperature-programed magnetic targeting and separation applications.     

Adsorption of CO, NH3 and O2 on Fe site of La0.875Sr0.125FeO3 (0 1 0) surface by density function theory calculation

The adsorption of CO, NH₃ and O₂ gas molecules on Fe site of La_0.875Sr_0.125FeO₃ (0 1 0) surface has been investigated based on the density functional theory (DFT) with the spin polarized generalized gradient approximation (GGA). The optimal adsorption orientations as well as the adsorption energies for these molecules adsorption on Fe site of La_0.875Sr_0.125FeO₃ (0 1 0) surface are derived. Results show that adsorption configurations with C-down for CO, N-down for NH₃ are stable. For the O₂ molecule adsorption, the mode with an angle about 120° between the oxygen molecule and La_0.875Sr_0.125FeO₃ (0 1 0) surface is stable.     

On the Nano/Micro-Mechanics of Metallic Glass

Metallic glass (MG) is amorphous and has some outstanding properties such as ultrahigh strength, superior elasticity, and excellent thermo-plasticity. However, as MG is relatively new to the metal family, the relationship between its physical properties and amorphous structure is still unclear. This article aims to provide an insightful discussion through a comprehensive review about the investigations in the past few decades on the scientific mechanisms of this class of material. The discussion of the paper will include the following key aspects: (1) the formation mechanism of an amorphous structure through glass transition, (2) the structural characterization and models, (3) the micromechanics of plastic event and shear band, and (4) the correlation between the amorphous structure and its mechanical properties.     

新天花粉蛋白的盐酸胍去折叠过程

本文利用荧光光谱和园二色光谱研究了新天花粉蛋白的盐酸胍去折叠过程.结果显示:新天花粉蛋白的盐酸胍去折叠是一个只包含天然蛋白和变性终态的二态过程,与已经报道的天花粉蛋白的盐酸胍去折叠过程不同.     

A device model for thin silicon-on-insulator SiGe heterojunction bipolar transistors with saturation effects

In this paper, we describe the saturation effect of a silicon germanium (SiGe) heterojunction bipolar transistor (HBT) fabricated on a thin silicon-on-insulator (SOI) with a step-by-step derivation of the model formulation. The collector injection width, the internal base—collector bias, and the hole density at the base—collector junction interface are analysed by considering the unique features of the internal and the external parts of the collector, as they are different from those of a bulk counterpart.     

基于DPLS特征提取的LDA方法在玉米近红外光谱定性分析中的应用

提出了一种基于DPLS+LDA的玉米近红外光谱定性分析新方法.该方法在训练时,首先用包含30个玉米品种每个品种20个近红外光谱样本的训练集进行DPLS回归,确定最佳DPLS主成分数为28;然后对训练集光谱进行DPLS特征提取后再进行LDA分析,确定最佳LDA主成分数为26,并提取LDA特征.识别时,测试样本经过DPLS...     

光纤分布式扰动传感器中瑞利和受激布里渊散射光谱特性及其影响研究

针对光纤分布式扰动传感器长距离应用定位误差增大的问题,研究了传感器长距离光纤中的瑞利散射和受激布里渊散射的光谱特性及其对系统定位精度的影响.建立了长距离光纤中瑞利和受激布里渊散射的数学模型,通过仿真研究发现散射光波的杂波干涉和强度噪声会严重降低干涉仪的光学信噪比,从而导致定位误差.通过实验验证了仿真结果的正确性.研究结...     

适配体修饰金硒纳米合金共振散射光谱法检测痕量Hg2+

用硼氢化钠还原法制备了金硒(AuSe)纳米合金.用单链核酸适配体(aptamer)修饰AuSe纳米合金制备了汞离子的核酸适配体纳米探针(Apta-AuSe).在pH 6.8 Na2HPO4-NaH2PO4缓冲溶液中及NaCl存在下,Apta-AuSe纳米探针亦不聚集;当Hg2+存在时,它可以稳定aptamer序列中的T...     

基于交换作用的纳磁逻辑电路片上时钟结构研究

纳磁逻辑电路具有低功耗、非易失和可常温下制备等优点, 实现低功耗片上时钟是其集成化的必备条件. 本文提出了一种基于交换作用的纳磁逻辑电路片上时钟结构, 用载流铜导线产生的奥斯特场将铁磁体薄膜覆层进行磁化, 然后依靠铁磁体层与纳磁体界面存在的交换作用场使后者磁化方向发生翻转. 与轭式铁磁体时钟用外磁场控制纳磁体磁化方向相比, 该方案在功耗方面降低了5/6, 时钟边界杂散场强度降低了2/3, 达到降低功耗、减轻串扰的目的. 此外, 采用微磁仿真进一步验证了该时钟结构上的纳磁体逻辑阵列可以实现逻辑功能. 关键词： 纳磁逻辑 片上时钟 交换作用