SiO2纳米线/纳米颗粒复合结构的制备及光致发光性能研究

采用热蒸发法制备了非晶SiO2纳米线/纳米颗粒复合结构,确定了非晶SiO2纳米线、微米颗粒及SiO2纳米线/纳米颗粒复合结构生长的工艺条件,并利用XRD、SEM、Raman、PL光谱等技术手段分析表征样品.实验结果表明,在不同的沉积温度范围内,生长样品的形貌和结构不同;SiO2纳米线/纳米颗粒复合结构的发光区与Si衬底明显不同,主要集中在黄绿光范围.     

草酸根作用下Co3O4八面体的控制合成

在草酸根的作用下,采用水热法合成了暴露八个(111)晶面的Co3 O4八面体.采用XRD、SEM、TEM和HRTEM等手段对产物进行了表征和分析,结果表明该Co3 O4八面体呈立方晶相且具有很高的结晶性.详细研究了反应时间、反应温度、草酸根浓度等反应条件对Co3 O4形貌的影响.研究表明草酸根可选择吸附在Co3 O4的(111)晶面,通过其较大的空间位阻限制(111)晶面的生长,从而使该晶面得以最终暴露.由于(111)晶面具有较高的能量,该Co3 O4八面体具有良好的高氯酸铵(AP)催化热分解性能.     

激基复合物给体作间隔层对激子复合区域的调节

为研究激基复合物器件激子复合区域的变化,在TPD/BPhen界面可形成激基复合物发光的基础上,以Ir(pq)2(acac)为探测层,制备器件ITO/Mo O_3(2.5 nm)/TPD((40-x)nm)/Ir(pq)2(acac)(0.5 nm)/TPD(x,x=0,3,6,10 nm)/BPhen(40 nm)/Cs2CO_3/Al,其中靠近BPhen的TPD称之为间隔层。电致发光光谱表明,该组器件的激子复合区域主要位于Ir(pq)2(acac)薄层和TPD/BPhen界面,分别发射595 nm和478 nm的光。随着TPD间隔层厚度的增加和电压的升高,发光区域向激基复合物区域(TPD/BPhen界面)移动,即更多的电子和空穴在TPD/BPhen界面形成激基复合物发光,Ir(pq)2(acac)发光减弱。当间隔层厚度由0 nm增至10nm时,6 V电压下的Ir(pq)2(acac)和激基复合物发光强度的比值由44降至1.5。对于间隔层厚度为6 nm的器件,Ir(pq)2(acac)和激基复合物发光强度的比值由6 V时的2.8降至10 V时的1.0。由此可见,激基复合物给体作间隔层能有效调节激子复合区域。     

未知纬度的捷联惯导系统晃动基座自对准方法

传统捷联惯导系统晃动基座对准方法中,一般要求提供当地准确的地理纬度信息,如果给定的纬度存在误差,会对初始对准精度造成影响.针对纬度未知情况下的晃动基座对准问题,提出了利用三个不同时刻的重力视运动向量的运算进行对准的方法,推导了三矢量定姿对准的基本原理.针对含有随机噪声的加速度计测量值构造的重力视运动向量会导致向量运算时出现共线向量的问题,设计了一种基于平均权重系数的自适应卡尔曼滤波器,能在未知动态环境下有效去除加速度计随机噪声,提高对准精度.仿真和试验结果表明,该方法可在纬度未知条件下完成捷联惯导系统晃动基座下的自对准并估计出纬度值,对准精度可达惯性器件误差所决定的对准极限精度.     

并行建表化学加速算法研究及其在气相斜爆轰模拟中的应用

采用详细化学反应机理对气相斜爆轰问题开展数值计算时,由于组分之间的特征时间尺度相差很大,反应源项的直接积分(direct integration,DI)求解通常存在强烈的刚性及非线性现象,导致计算量很大.为了在不损失计算精度的基础上有效减少化学反应过程的计算时间,针对包含2H2+O2详细机理的二维斜爆轰并行计算,提出两...     

基于转捩SST模型凸起圆柱绕流数值研究

为了研究局部凸起对边界层转捩的影响,采用转捩SST模型分别对亚临界、临界和超临界状态下带突起的圆柱绕流问题进行了数值模拟,分析了不同Reynolds数下带突起的圆柱绕流问题的近壁面流动特征以及表面时均压力与摩擦力系数的分布和凸起对圆柱表面流动分离以及转捩的影响,对比了有无凸起两侧圆柱表面时均压力、摩擦力系数的不同. 结果表明:当来流Reynolds数处于临界区时,气流在圆柱上表面凸起处形成了3个反向旋转的漩涡,之后随着θ的增大,发生了流动分离和流动转捩现象;对于不同Reynolds数下的来流,圆柱上表面的凸起可以使气流发生转捩的位置提前;圆柱上表面的凸起使流速增大、压强降低,从而导致圆柱产生升力,随着来流Reynolds数的增大,其升力逐渐变大.      

Efficient Detection of Environmental Estrogens Bisphenol A and Estradiol By Sensing System Based on AuNP-AuNP-UCNP Triple Structure

A sensing system based on AuNP-AuNP-UCNP triple structure for efficient detection of dual targets bisphenol A and estradiol was constructed. In the preparation of triple structure, the gold nanoparticles (AuNPs) and upconversion nanoparticles (NaYF₄: Yb, Er, Gd, UCNPs) were synthesized and surface modified. Then, the two nanoparticles and their aptamers were connected to form two kinds of optical fluorescent probes. A nucleic acid sequence that matches with two aptamers was designed, rendering the probes to get close based on the principle of complementary base pairing. On the basis of this, a sensing system with triple structure was prepared, and its connecting effect was characterized by TEM. With this system, dual targets of bisphenol A and estradiol were detected efficiently and conveniently through quantitatively determination by fluorescence and UV spectrophotometer. At the reaction temperature 30 °C and pH 7.8, this method exhibited good linear range for determination of bisphenol A and estradiol from 2 ng mL^–1 to 200 ng mL^–1 and from 10 ng mL^–1 to 150 ng mL^–1, with the limits of detection of 0.2 ng mL^–1 and 0.5 ng mL^–1, respectively. This sensing system with triple structure owned better specificity to structural and functional analogues, showed good repeatability and stability. What's more, this sensing system could be applied to actual water detection, with the recoveries of 86.1%–107.4%, and the relative standard deviation below 6.8%. This method shows promising applications in other environmental estrogens in water sample.     

Preparation of flame‐retardant polyamide 6 by incorporating MgO combined with g‐C3N4

Flame‐retardant polyamide 6 (PA6) was prepared by an inorganic‐organic composite (MCN or MgO/g‐C₃N₄) synthesized by incorporating magnesium oxide (MgO) combined with graphitic carbon nitride (g‐C₃N₄). As compared to g‐C₃N₄, MCN possessed a laminate structure, more holes, and a larger specific surface area. The addition of MCN could effectively improve the flame retardancy and mechanical properties of PA6 due to its better compatibility and dispersion in the PA6 matrix. When the addition of MCN was 20 wt%, the vertical combustion performance of the PA6/MCN sample reached flammability rating V‐0 (UL‐94) and the limiting oxygen index (LOI) was up to 32.1%. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that the introduction of MCN efficiently enhanced thermal stability of PA6. The morphologies of the char residue observed by scanning electron microscopy (SEM) verified that MCN promoted the formation of sufficient, compact, and homogeneous char layers on the composite's surface during burning. Thus led to increase the char layer strength and improve the flame retardancy of PA6. The thermogravimetric analysis/infrared (TG‐IR) revealed the gas‐phase retardancy mechanism of MCN. Compared with PA6/g‐C₃N₄, PA6/MCN showed better mechanical properties in terms of flexural strength and tensile strength.     

A facile route for regioselective conjugation of organo-soluble polymers onto chitosan

A facile route is described for the regioselective conjugation of organo-soluble polymers onto chitosan under very mild conditions, using SCC as intermediates. SCC could be prepared simply by mixing chitosan acidic aqueous solution with SDS. PEG or PCL were then grafted to SCC using the NHS/DCC coupling method. In addition, the polymers were found to be linked to chitosan through the hydroxyl groups of chitosan when stoichiometric SCC was used as a precursor. SDS could be removed simply by either precipitating the solution of SCC-graft-polymer in DMSO into Tris aqueous solution or dialyzing against Tris solution.     

火焰原子吸收光谱法测定镍基高温合金中的镉

采用火焰原子吸收光谱法测定镍基高温合金中的镉,样品以硝酸-氢氟酸-水混合溶液(1+1+1)前处理,选择Cd 228.8 nm为分析线进行测定,并通过标准加入法校正基体效应。考察了消解酸的选择,仪器工作参数的调整,基体和共存离子对镉测定的影响。结果表明,镍基高温合金中镉的检出限为0.088μg/g。加标回收率为94.1%~109%,结果的相对标准偏差(RSD,n=8)在0.54%~1.6%。方法操作简便、分析速度快、准确度好,适用于镉含量在0.0001%~0.001%的镍基高温合金中的测定。