五羟色胺分子选择性电极研究

本应用自己合成的联萘２０－冠－６作为活性载体，进行了五羟色胺分子选择性电极研究。电极在１０＾－＾５－１０＾－＾２ｍｏｌ／Ｌ浓度范围内对五羟色胺具有稳定的线性响应，平均斜率为６３ｍＶ／ＰＣ，检测下限为２．７×１０＾－＾６ｍｏｌ／Ｌ。     

Deep desulfurization by oxidation using an active ionic liquid‐supported Zr metal–organic framework as catalyst

In this study, a Zr metal–organic framework (UIO‐66) was synthesized with zirconium tetrachloride and terephthalic acid using the solvent method. Then various masses of 1‐methylimidazolium‐3‐propylsulfonate hydrosulfate (PSMIMHSO₄) were supported on the UIO‐66 as catalysts, which were used for catalytic oxidative desulfurization. Sulfur removal using 400 mg of 40% PSMIMHSO₄ supported on the UIO‐66 of greater than 94% was obtained at 313 K for 20 min with an O/S molar ratio of 7:1. The results obtained in this work could provide useful information for the design of water‐stable metal–organic frameworks with permanent porosity in applications of catalytic oxidative desulfurization. Copyright © 2014 John Wiley & Sons, Ltd.     

A high-order full-discretization method using Hermite interpolation for periodic time-delayed differential equations

A high-order full-discretization method(FDM)using Hermite interpolation(HFDM) is proposed and implemented for periodic systems with time delay. Both Lagrange interpolation and Hermite interpolation are used to approximate state values and delayed state values in each discretization step. The transition matrix over a single period is determined and used for stability analysis. The proposed method increases the approximation order of the semidiscretization method and the FDM without increasing the computational time. The convergence, precision, and efficiency of the proposed method are investigated using several Mathieu equations and a complex turning model as examples. Comparison shows that the proposed HFDM converges faster and uses less computational time than existing methods.     

Fire retarded polyurethane foam composites based on steel slag/ammonium polyphosphate system: A novel strategy for utilization of metallurgical solid waste

A series of FR-RPUF composites were prepared by a one-step water foaming process with ammonium polyphosphate (APP) and steel slag (SS) as flame retardants. Thermogravimetric analysis (TG), limiting oxygen index (LOI), UL-94 vertical combustion test, microscale combustion calorimetry (MCC), TG-Fourier transform infrared spectrometry (TG-FTIR), scanning electron microscopy (SEM), Raman spectra and FTIR were used to investigate the thermal stability, flame retardancy, combustion performance, gas phase products, and char residue morphology of FR-RPUF composites. TG test results showed that the initial decomposition temperature (T_-5wt%) and char residue rate at 700°C of RPUF/APP/SS composites were significantly enhanced by the addition of APP and SS, and the thermal stability of the composites was improved. Flame retardant test results confirmed the significantly increased LOI values of RPUF/APP/SS composites with V-0 rating. TG-FTIR also confirmed the obviously decreased release of toxic gases and flammable gases in the combustion of RPUF/APP/SS composites. SEM and Raman spectra of char residues for the composites suggested that APP/SS system improved the compactness and graphitization degree of char layer for RPUF/APP/SS composite. The above researches provide a new strategy for the utilization of SS in fire safety engineering.     

The calcined zeolitic imidazolate framework-8 (ZIF-8) under different conditions as electrode for supercapacitor applications

Zeolitic imidazolate framework-8 (ZIF-8) is synthesized by typical solvothermal method and subsequently calcined under air and nitrogen atmosphere, respectively. The carbon in the calcined ZIF-8 under nitrogen atmosphere was from the carbonization of the guest molecules, without adding any other carbon sources. The samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and electrochemical analyzer system. When the ZIF-8 is used as electrode materials for a supercapacitor in 6 M KOH electrolyte, it displays a pseudocapacitive behavior. The untreated ZIF-8 and calcined ZIF-8 under air and nitrogen atmosphere electrodes exhibit a specific capacitance of 96, 156, and 185 F g^?1, respectively, at a scan rate of 5 mV s^?1 and good stability over 1,500 cycles. These results indicate that the ZIF-8 is a promising material for supercapacitors.     

应用纳米零价铁富集银的研究

大量研究表明,纳米零价铁（nanoscale Zero-Valent Iron,nZVI）对水中重金属,尤其是金、银等稀贵金属,有良好的分离富集作用.利用纳米零价铁反应器证明了nZVI可从废水中分离低浓度的银离子（Ag⁺）,并生成高含量的“银矿石”.此外,也证明了反应区氧化还原电位能够反映nZVI与Ag⁺的反应速率和分离效率.利用X射线衍射仪、X射线光电子能谱和高分辨透射电子显微镜等手段对反应产物进行表征,证实了Ag⁺可被nZVI还原为单质银,并以纳米颗粒的形式（<10 nm）沉积在nZVI表面.与其他材料（常见吸附/还原材料）相比,nZVI具有效率高,受pH影响小的优点.研究结果表明,nZVI是一种能够高效富集痕量银资源并产生高价值纳米银的材料.     

Sub-Riemannian constant mean curvature surfaces in the Heisenberg group as limits

The 3-dimensional Heisenberg group H together with its standard sub-Riemannian metric g₀ is viewed as the limit of a family of Riemannian manifolds, (H,g_u), u>0. For each u>0, we consider some invariant surfaces with constant mean curvature in (H,g_u). These surfaces of (H,g_u) have very nice limits as u0. We then define the mean curvature of a hypersurface in (H,g₀) to be the limit of its mean curvature in (H,g_u). We show that in a more general case, this definition is appropriate. Mathematics Subject Classification (2000) Principal 53C17; Secondary 22E25     

SUBMANIFOLDS OF PRODUCT RIEMANNIAN MANIFOLD

1IntroductionLetUandVbeRiemannianmanffolds,withthedimensionn1andn2respectively.UxVistheRiemannianproductofUandV.WedenotebyPandQtheprojectionmappingsofT(UxV)toTUaildTVrespectively.ThenwehaveWeputJ=P-Q.ItiseasytoseethatJ~=I.WedefineaRiemannianmetricofUxVbyg(X,Y)==g1(PX,PY) g2(QX,QY),wllereg1andg2areRiemannia11metricofUandVrespectively.ItfollowsthatBy7wedellotetheg'sLevi-Civitaconnection.ThenwecaneasilyseethatInfact,Frollltlledefillitiollofg,wecangetthatUalldVareallgeodesicsub…     

Melting in two-dimensional Yukawa systems: a Brownian dynamics simulation

We studied the melting behavior of two-dimensional colloidal crystals with a Yukawa pair potential by Brownian dynamics simulations. The melting follows the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) scenario with two continuous phase transitions and a middle hexatic phase. The two phase-transition points were accurately identified from the divergence of the translational and orientational susceptibilities. Configurational temperatures were employed to monitor the equilibrium of the overdamped system and the strongest temperature fluctuation was observed in the hexatic phase. The inherent structure obtained by rapid quenching exhibits three different behaviors in the solid, hexatic, and liquid phases. The measured core energy of the free dislocations, E(c) = 7.81 ± 0.91 k(B)T, is larger than the critical value of 2.84 k(B)T, which consistently supports the KTHNY melting scenario.     

反铁电相变陶瓷低频发射换能器

在具有高阶形式的广义压电方程基础上,讨论掺镧改性锆锡钛酸铅PbLa(Zr,Sn,Ti)O3(PLZST)反铁电相变陶瓷的非线性机电耦合问题,得到类似传统线性压电方程的近似线性电致伸缩方程,给出了一种解决非线性反铁电相变陶瓷换能器电声转换问题的分析方法,即在直流偏置状态下对PLZST反铁电相变陶瓷的材料参数进行近似线性等效化处理进而分析换能器的电声转换问题.在此基础上,研制了水中谐振频率1.1 kHz新型反铁电相变陶瓷低频弯张换能器.湖上试验结果表明,与同结构同尺寸压电陶瓷弯张换能器相比,目前反铁电换能器样品的发射电压响应约高3dB,声源级高出9dB,并验证了本文所提出的分析非线性反铁电相变陶瓷换能器方法的正确性.