带电多孔二氧化硅纳米颗粒在硫醇/磷脂混合双层膜上的非特异性吸附

制备了表面带阴/阳离子的多孔二氧化硅纳米颗粒, 通过QCM-D研究了颗粒在不同pH值环境下与磷脂膜的非特异性吸附情况. 结果表明, NH₂-MSN 在4–8的pH值范围内与磷脂膜相互吸引, 而COOH-MSN由于与磷脂膜的电性始终保持一致而无法发生吸附现象. 本研究能够帮助理解和预测纳米颗粒与细胞膜间的相互作用, 为药物输运提供载体, 有助于多孔二氧化硅纳米颗粒在药物输运体系中的应用. 关键词： 多孔二氧化硅纳米颗粒 磷脂膜 非特异性吸附 QCM-D     

SiO2包覆共轭聚合物CN-PPV纳米探针的制备与荧光性质

采用纳米沉淀法制备了半导体聚合物CN-PPV纳米粒子,并用改进的Stber方法对纳米粒子进行包覆,获得了发光稳定的SiO2/CN-PPV纳米粒子。用动态光散射(DLS)及透射电镜(TEM)方法对粒子尺寸进行了表征,结果表明包覆前的CN-PPV纳米粒子平均粒径约为30 nm,包覆获得SiO2/CN-PPV纳米粒子的平均粒径约为60 nm。通过紫外-可见吸收光谱及荧光光谱对包覆前后纳米粒子的发光性质进行了比较,发现共轭聚合物CN-PPV包覆后的发射光谱与包覆前相比发生了小的蓝移,表明共轭聚合物的分子构型可能发生了微小变化。SiO2包覆可以提高聚合物发光分子的光稳定性,并且提供用于生物分子耦联的表面,这类材料有望在生物医学成像中获得应用。     

ZnAl2O4：Tb3+荧光粉的合成、结构及其光学性能研究

通过溶胶-凝胶法制备出不同Tb³⁺掺杂浓度和不同二次煅烧温度下的ZnAl₂O₄:Tb³⁺荧光粉, 并利用X射线衍射(XRD)和荧光光谱等对样品进行了表征。由XRD结果可知,当Tb³⁺掺杂的摩尔分数不大于9%,二次煅烧温度在600℃以上时,所得粉体为结晶性良好的尖晶石相。在紫外光激发下,ZnAl₂O₄:Tb³⁺荧光粉的发射光谱由位于488 nm(⁵D₄→⁷F₆)、542 nm(⁵D₄→⁷F₅)、587 nm(⁵D₄→⁷F₄ )和621.5 nm(⁵D₄→⁷F₃)的4个发射峰组成。研究发现,Tb³⁺的掺杂浓度和二次煅烧温度对样品发光强度有着重要影响,当Tb³⁺的摩尔分数为5%,二次煅烧温度为900℃时,ZnAl₂O₄:Tb³⁺荧光粉的发光最强,继续增加Tb³⁺掺杂浓度或提高煅烧温度,分别会出现浓度猝灭和温度猝灭现象。     

双平行圆柱形MDM纳米棒等离子体波导的传输特性分析

设计了一种由双平行圆柱形纳米棒构成的金属-介质-金属(MDM)型等离子体波导,采用时域有限差分方法(FDTD)分析了波导结构的传输特性。当光波垂直主轴入射时,电磁场被很好地局限在两纳米棒所形成的中间区域以及介质层中,从而在该波导中能够有效地耦合电磁场能量。在工作波长为1 550 nm的情况下,随着内层金属芯半径的增大,有效折射率减小,传播距离增大;而中间介质层厚度增大时,有效折射率增大,传播距离减小。当外层金属壳厚为20 nm时,电场可以很好地被限制在纳米棒的介质层内。上述结果表明:通过调整波导结构的几何参数可以显著提高金属纳米棒的场限制,降低波导本身的损耗, 使波导的有效折射率和传播长度达到最优化。这种等离子体波导能够实现亚波长的光限制,可以应用于光子器件集成和传感器领域。     

电子束泵浦氧化锌基量子阱的斯塔克效应

在不同功率密度的电子束泵浦条件下,对ZnO/Zn0.85Mg0.15O非对称双量子阱的荧光光谱进行了研究,并采用蒙特卡罗仿真模拟对测试结果进行了分析。模拟的结果和实验结果高度吻合。观测到了不随穿透深度变化的阱区发光峰红移,证明表面电荷积累引起了量子限域斯塔克效应。     

改进的三维电磁PIC系统模拟并行算法

为了更好地实现对大尺度器件的模拟,以及更系统地验证和解决高功率微波系统在设计和实验中负载变化等影响,在进一步深入研究电磁PIC并行算法的基础上,运用MPI消息传递函数做出了改进。提出了一种整体建模、分段解析的并行算法,并从并行时序算法入手,通过减少一次同步提高了计算的效率。最后经过一个磁绝缘线振荡器进行验证,改进的算法正确,并且当计算进程数4个增加到16个时,计算速度能提高2.5倍左右。     

基于电化学与热能的耦合关系演算聚合物锂离子动力电池的温度状态及分布

基于电化学-热耦合模型研究聚合物锂离子动力电池放电过程热行为, 分析了放电倍率、冷却条件对电池放电过程的温度变化及分布的影响规律. 结果表明: 3C放电时, 模型计算结果与实测结果的平均偏差为0.57 K, 方差为0.15, 说明模型准确度较高. 电芯的平均生热率在整个放电过程中呈现出增加的趋势, 初期和末期增长较快. 大倍率放电时, 与电流密度的平方呈正比的不可逆热所占的比重较大, 小倍率放电时, 电化学反应可逆热占主导. 改善冷却条件能降低电池放电过程的平均温度, 对流传热过程的表面传热系数为5 W/(m²·K), 1 C, 3 C, 5 C放电结束时, 电芯的平均温升为分别为6.46 K, 17.67 K, 27.53 K, 当对流传热过程的表面传热系数增加至25 W/(m²·K)时, 温升比自然对流条件下相同倍率放电时的温度分别降低了2.91 K, 4.68 K, 5.62 K, 但电芯温度分布的不一致性也会加剧. 关键词： 电化学 耦合 锂离子动力电池 温度分布     

The Peierls Instability in Pinning Potentials from Counterions

In the presence of a pinning potential both the nature of the Peierls transition and the dynamics of the Charge Density Wave are affected. We argue that the periodic potential stabilizes phase solitons, while amplitude solitons can be polarons or bipolarons. For these excitations we give both the extension along the chain as well as the energies of formation. We only discuss the case of a periodic pinning potential as arising from a counterion lattice; neglecting randomness from impurities.     

Sensitive Parameter Predicting Steady-State Pressure Difference of Partially Crosslinked Polyacrylamide Suspension in Core Flow Experiments

Using artificial cores, six different partially crosslinked polyacrylamide (PCPAM) suspensions were used for sandpacked core flow experiments; the results indicated that the migration of the PCPAM particles through porous media was a process of plugging and flooding at the same time. A theoretical model was proposed and the sensitive parameter, G′, was determined by rheological oscillation measurements with a 200 μm plate gap. In addition, the validity of the proposed theoretical model was verified by the results of the core flow experiments and a fitting equation of ΔP ₁ with G′ was obtained which can be used for quantifying the steady-state pressure of PCPAM suspensions flowing through porous media in the core flow experiments.     

Preparation and Mechanical and Tribological Properties of High-Density Polyethylene/Hydroxyapatite Nanocomposites

High-density polyethylene (HDPE) nanocomposites reinforced with hydroxyapatite nanorods (nHA) were fabricated by means of extrusion and injection molding. The thermal, mechanical, and dry sliding wear properties of HDPE-based nanocomposites filled with nHA loadings up to 20 wt% were investigated. The results of mechanical property characterization showed that nHA additions improved the hardness, elastic modulus, and yield strength of HDPE at the expense of its tensile ductility and impact strength. Thermogravimetric analysis and heat deflection temperature measurements revealed that nHA fillers are very effective to enhance the thermal stability of HDPE. The wear behavior of HDPE/nHA nanocomposites was studied using a pin-on-disk tribometer. nHA fillers of a large aspect ratio improved the wear resistance of HDPE substantially because of their load-bearing effect and the formation of a continuous transfer film on the steel counterface.