PANI-Fe_3O_4复合材料的制备及其电磁参数匹配特性的数值模拟

以电损耗型吸波剂为研究基础,根据传输线理论模拟获得给定条件下的理想电磁参数区域,考察厚度(d)、频率(f)、反射率(R)等因素对理想电磁参数区域的影响。将模拟结果与导电聚苯胺(PANI)的测试结果进行对比,给出吸波剂改性方向并预测不同频段下的吸波性能。结果显示,在中空结构PANI表面负载Fe_3O_4后,复合材料的介电损耗降低,磁损耗增加,介电损耗角正切(tanδ_ε)和磁损耗角正切(tanδ_μ)相接近,电磁匹配特性得到改善,上述实验结论与模拟结果相吻合。     

胺基改性磁性纳米石墨片复合材料的制备与表征

以纳米石墨片(GNS)为载体,FeCl_3·6H_2O为前驱体,乙二胺为改性剂和还原剂,乙二醇为表面活性剂和还原剂,无水乙酸钠为稳定剂,通过溶剂热法一步制备了胺基改性磁性GNS(NH_2-GNS/Fe_3O_4)纳米复合材料.利用透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)和振动样品磁强计(VSM)对样品进行了表征,并研究了其对水溶液中Ag(Ⅰ)的吸附性能.结果表明,NH_2-GNS/Fe_3O_4纳米复合材料的磁性能可以满足固液相分离的要求.NH_2-GNS/Fe_3O_4纳米复合材料对Ag(Ⅰ)具有吸附性能,且在对Ag(Ⅰ)的吸附过程中将Ag(Ⅰ)还原为单质银,该吸附过程为发生在均质表面的单层吸附.     

Validation of 1D model for methane/air/Pt combustion in stagnation flow

A 2D model is built on the package of FLUENT to study the effects of radial aspect ratio (R/W), length-to-width ratio (L/W), strain rate (S _R), and buoyancy (Ri=Gr/Re ²) on the validation of the simplified 1D model. In the present 2D model, the methane/air homogeneous reaction mechanism of Peters and the methane/air/platinum heterogeneous reaction mechanism of Deutschmann are applied. By comparison between the 1D and 2D numerical results, it is found that the validation of 1D model is highly related with the catalytic stagnation reactor configuration. For length-to-width ratio L/W = 1 configuration, 1D laminar model is applicable when the radial aspect ratio R/W > 0.4. For R/W = 0.6, the reactor exhibited 1D characteristics when L/W < 1. Compared with the temperature and species profiles, the velocity distribution along the axis is more sensitive to the change of radial aspect ratio and length-to-width ratio. With increasing of the strain rate, the flame front goes closer to the catalytic wall surface and the difference between the 1D and 2D results decreases. For a valid 1D simulation, it is recommended that the strain rate should be greater than 20 s^-1. The effects of natural convection can be neglected when Ri < 5.     

四分Cantor测度的谱性质

自仿测度μM,D谱性质的研究始于四分Cantor测度μ4(即M=4,D={0,2}的情形).在长期从事谱集研究的基础上,Jorgensen和Pedersen在1998年首次发现μ4是一个具有谱性质的分形测度,其谱Λ(M,S)与和谐对(M~(-1)D,S)密切相关,其中S={0,1}.近年来的研究表明,对于某些奇数l,数乘集合lΛ(M,S)也是测度μ4的谱.这使得测度μ4的一些谱具有较强的稀疏性.本文重点对具有上述性质的奇数l进行讨论.利用数论中同余关系和有限群中元素的阶的性质,得到当l分别为素数、素数幂和素数乘积时,lΛ(M,S)为谱的判别依据,改进推广Dutkay等人的工作.     

槲皮素磁性分子印记聚合物的制备及其吸附性能

以槲皮素(Qu)为模板分子、N-乙烯基吡咯烷酮(NVP)和丙烯酸(AA)为功能单体、N,N′-亚甲基双丙烯酰胺(MBA)为交联剂、H2O2-Vc为引发剂、KH570修饰的Fe3O4纳米颗粒为磁性载体,借助表面分子印迹技术制备了能够对Qu进行特异性识别的槲皮素磁性分子印迹聚合物(Qu-MMIPs)。利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FT-IR)、振动样品磁强计(VSM)和紫外-可见分光光度计(UV-Vis)对样品进行了结构和性能表征。结果表明:Fe3O4磁性载体表面已成功包覆了分子印迹聚合物。与化学组成相同的磁性非印迹聚合物(Qu-MNIPs)相比,Qu-MMIPs对Qu有较高的吸附选择性。静态吸附平衡实验和Scatchard分析结果表明,Qu-MMIPs中存在两类不同的结合位点,平衡解离常数分别为1.646×10-6 mol/L和6.387×10-6 mol/L,最大吸附量分别为23.041mg/g和29.923mg/g。