JP-10裂解的激波管实验与动力学模拟

利用单脉冲激波管对碳氢燃料JP-10在1150~1300K条件下的高温热裂解特性进行了实验研究,采用气相色谱法分析热裂解产物并获得了热裂解速率系数.主要裂解产物有乙烯、乙炔、丙烯、丁烯、1,3-丁二烯、环戊二烯、环戊烯、苯、甲苯,以及少量的甲烷、乙烷、二甲苯和甲基环戊烯.将每次激波管实验后所有产物浓度累加, JP-10裂解速率系数由实验测定.为了消除激波运行中非理想性和边界层效应导致反应温度确定的误差,采用对比速率法确定裂解温度,即在反应物中加入少量热解速率已知的内标物,根据内标物在相同的激波管实验条件下的裂解程度确定反应温度.根据内标物裂解量确定的激波管裂解反应温度通常小于采用传统测量激波速度由激波关系计算的反射激波后5区温度.在1200~1300K之间两种方法得到的温度吻合得较好,差异在20K以内,随着温度升高,两者差异增大.在实验研究的基础上,依据San Diego Mechanism对JP-10高温裂解过程进行了动力学模拟.结果显示:主要裂解产物中乙烯、乙炔和1,3-丁二烯产量随温度变化的实验值与San Diego Mechanism的模拟结果有很好的一致性,但环戊烯产量的实验值比模拟值高很多,预示JP-10裂解中完全开环和部分开环反应都是重要的裂解通道.      

Numerical study of buoyancy- and thermocapillary-driven flows in a cavity

Thermocapillary- and buoyancy-driven convection in open cavities with differentially heated endwalls is investigated by numerical solutions of the two-dimensional Navier-Stokes equations coupled with the energy equation. We studied the thermocapillary and buoyancy convection in the cavities, filled with low-Prandtl-number fluids, with two aspect-ratiosA=1 and 4, Grashof number up to 10⁵ and Reynolds number ⋎Re⋎≤10⁴. Our results show that thermocapillary can have a quite significant effect on the stability of a primarily buoyancy-driven flow, as well as on the flow structures and dynamic behavior for both additive effect (i.e., positiveRe) and opposing effect (i.e., negativeRe).     

大散射角散斑场中有关相位奇异新特性的研究

利用散斑场和参考光的干涉提取散斑场复振幅和相位, 研究了不同散射角下散斑场相位的分布规律以及相位奇异处光波复振幅实部零值线和虚部零值线夹角、光强等值线离心率的统计特性. 在大散射角散斑中发现了一种新的相位奇异现象, 即相位奇异线; 研究了相位在跨越奇异线时的突变规律及涡旋状相位的分布特征, 发现在相位奇异线处存在着呈双曲线或抛物线状的光强等值线.     

基于1/f噪声的NPN晶体管辐照感生电荷的定量分离

本文针对NPN双极性晶体管, 在研究辐照感生的氧化层电荷及界面态对晶体管基极电流和1/f噪声的影响的基础上, 建立辐照感生氧化层电荷及界面态与基极电流和1/f噪声的定量物理模型. 根据所建立的模型, 提出一种新的分离方法, 利用1/f噪声和表面电流求出氧化层电荷密度, 利用所求得氧化层电荷密度和表面电流求出界面态密度. 利用本方法初步实现了辐照感生氧化层电荷及界面态的定量计算.     

Synthesis and Electronic/ionic Transport Properties of MoO2/rGO Anode for Lithium Ion Batteries

MoO₂/rGO (reduced graphite oxide) composites have been synthesized by hydrothermal method followed by anneal and characterized by X‐ray diffraction (XRD) and scanning electron microscope (SEM). Galvanostatic charge/discharge testing and electrochemical impedance spectroscopy (EIS) techniques are employed to evaluate the kinetic behaviors of the MoO₂/rGO during lithiation/delithiation. The obtained MoO₂‐based materials have monoclinic crystal structure, and worm like shape with average dimensions of 100‐200 nm width and 500 nm‐1 μm length. There are two steps of lithium ion intercalation/de‐intercalation for the MoO₂/rGO anode at the potential ranging from 1.0 to 3.5 V, locating at E_Li/Li⁺ = 1.60/1.75 V, 1.25/1.40 V, and the first discharge and charge capacities are, respectively, 221.0 and 185.4 mAh g^?1. The resistances of R_SEI and R_CT for the MoO₂/rGO anode are 2‐4 Ω and below 5 Ω. Moreover, the lithium diffusion coefficient calculated from the EIS measurement is about 3.6×10^?9 cm² s^?1.     

Enantioseparation of Phenylsuccinic Acid Enantiomers Using Aqueous Two-Phase Flotation and Their Determination by HPLC and UV Detection

Aqueous two-phase flotation (ATPF) is especially applicable to bioseparation. However, there is no previous work reporting on its application in enantioseparation. Using phenylsuccinic acid (H₂A) as the model enantiomers, ATPF was first introduced into the field of chiral separation. The contributions of a series of ATPF systems to the enantioseparation were investigated. The results indicated that an appropriate increase in the amount of phase-forming components and a decrease in pH values (from 5.5 to 2) are both beneficial for the enantioseparation. Enantioselective flotation and partitioning behavior are mainly dependent on pH values of the solutions, types, and concentrations of chiral selectors. Furthermore, salt, PEG, flow rates of air, and flotation time also have some effects on the enantioseparation. Under the optimal conditions, the enantioselectivity was calculated in terms of the separation factor (α) and enantiomer excess (e.e. %) as 1.99 and 23.49 %, respectively. Finally, the most reasonable mechanisms for H₂A enantioseparation in ATPF system have been proposed. An ATPF system composed of PEG2000/(NH₄)₂SO₄ was proved to have the best ability for the separation of H₂A enantiomers. The explorations in our study will further enrich the enantioseparation methods and pave the way for the application of ATPF in the enantioseparation field.     

Density functional theory study of p‐chloroaniline adsorption on Pd surfaces and clusters

The adsorption mode of aromatic molecules on transition metal surfaces plays a key role in their catalytic transformation. In this study, by means of density functional theory calculations, we systematically investigate the adsorption of p‐chloroaniline on a series of Pd surfaces, including stepped surfaces, flat surfaces, and clusters. The adsorption energies of p‐chloroaniline on these substrates [Pd(221), Pd(211), Pd(111), Pd(100), Pd₁₃‐icosahedral, Pd₁₃‐cubo‐octahedron, Pd₅₅] are ?1.90, ?2.13, ?1.70, ?2.11, ?2.53, ?2.65, ?2.23 eV, respectively. Benzene ring is adsorpted on catalyst rather than amine group in p‐chloroaniline molecular. A very good linear relationship is further found between the adsorption energies of p‐chloroaniline and the d‐band center of both Pd surfaces and clusters. The lower of d‐band center of Pd models, the stronger adsorption of p‐chloroaniline on catalysts. In addition, the frontier molecular orbital and density of states analysis explain the adsorption energy sequence: cluster Pd₁₃ > stepped Pd(221) surface > flat Pd(111) surface. © 2014 Wiley Periodicals, Inc.     

Investigation on “Excimer” Formation Mechanism of Linear Oligofluorenes‐Functionalized Anthracenes by Using Transient Absorption Spectroscopy

We study the photophysical characters of two oligofluorenes‐functionalized anthracenes molecules with different fluorine‐vinylene (FV) units, which exhibits that “excimer” state appears in the solution after photoexcitation. The dynamic data shows that two mechanisms are responsible for the generation of “excimer”. The fast one is controlled by the arene‐arene interaction between molecules and the slow one is influenced by the diffusion motion of molecules. Increasing the number of FV units may suppress the DM‐dependent “excimer” and enhance the yield of intrinsic fluorescence, which finally improves the fluorescence property of molecules in solution.     

Simultaneous analysis of citrulline and arginine in serum and tissue

We developed a method for simultaneously determining l-citrulline and l-arginine levels in serum and tissue samples using RP-HPLC with ultraviolet (UV) detection. The serum was deproteinized by trichloroacetic acid and heat; the tissue was homogenized by trichloroacetic acid and deproteinized as the same as serum. Phenyl-isothiocyanate (PITC) solution was used as derivatization reagent and a gradient elution was carried out. The linearity for l-arginine and l-citrulline ranged from 0 to at least 1000 μmol/L. R² values were above 0.9999 for both. LODs for l-arginine and l-citrulline were 0.0462 μmol/L and 0.0195 μmol/L, respectively, while LOQs were 0.530 μmol/L and 0.417 μmol/L, respectively. Intra- and inter-day CVs were less than 3.5% and 7.5% in serum, respectively. The average recovery was from 85.5% to 116.5% in serum. Intra-assay CVs were 3.8% and 10.3%, and inter-assay CVs were 13.7% and 10.7% for l-arginine and l-citrulline respectively in tissue. The average recovery was from 92.8% to 113.5% in tissue. This is a reliable and convenient analytical method which is suitable for most clinical laboratories.