Electrochemical behaviors of GMP based on solid-phase extractionon at Cu-Mg-Al hydrotalcite-like compound (HTLC) modified glass carbon electrode

Guanosine-5′-monophosphate (GMP) was investigated the electrochemical behaviors based on solid-phase extractionon (SPE) at Cu-Mg-Al hydrotalcite-like compound (HTLC) modified glass carbon electrode. Cu-Mg-Al hydrotalcite-like compound (HTLC) was proved as a new sorbent for SPE of GMP, which showed an irreversible adsorption oxidation process on the HTLC/GCE with the oxidation peak potential located at 1.15 V (vs. SCE) in a pH 5.0 acetate buffer solution. Influencing factors of the electrochemical behavior of GMP on the HLTC/GCE were optimized and kinetic parameters were calculated. Under the optimal conditions, with differential pulse voltammetry (DPV), a linear relationship was obtained between the oxidation peak current and the GMP concentration in the range from 1.0 × 10^− 6 to 8.0 × 10⁻⁴ mol L⁻¹ with the detection limit as 5.0 × 10⁻⁷ mol L⁻¹ (signal-to-noise ratio of 3). The modified electrode surface has very good reproducibility and stability.     

A series of trinuclear sandwich-like cyanide-bridged iron(III)-manganese(II) complexes: synthesis,crystal structures,and magnetic properties

Four pyridinecarboxamide iron dicyanide building blocks and one Mn(III) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in a series of trinuclear cyanide-bridged Fe^III–Mn^II complexes: {[Mn(DMF)₂ (MeOH)₂][Fe(bpb)(CN)₂]₂}·2DMF (1), {[Mn(MeOH)₄][Fe(bpmb)(CN)₂]₂}·2MeOH·2H₂O (2), {[Mn(MeOH)₄][Fe(bpdmb)(CN)₂]₂}·2MeOH·2H₂O (3) and {[Mn(MeOH)₄][Fe(bpClb)(CN)₂]₂}·4MeOH (4) (bpb²⁻ = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpdmb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, bpClb²⁻ = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate). Single-crystal X-ray diffraction analysis shows their similar sandwich-like structures, in which the two cyanide-containing building blocks act as monodentate ligands through one of their two cyanide groups to coordinate the Mn(II) center. Investigation of the magnetic properties of these complexes reveals antiferromagnetic coupling between the neighboring Fe(III) and Mn(II) centers through the bridging cyanide group. A best fit to the magnetic susceptibilities of complexes 1 and 3 gave the magnetic coupling constants J = −1.59(2) and −1.32(4) cm⁻¹, respectively.     

Preparation of cobalt hydroxide film modified electrode and its analytical application

Cobalt hydroxide film modified electrode was prepared by depositing cobalt hydroxide on glassy carbon electrode (GCE) surface in an alkaline aqueous solution and then characterized by cyclic voltammetry. The electrochemical behavior of resorcin on the film modified electrode was investigated. The results show that cobalt hydroxide films in alkaline solutions have good electrocatalytical activity towards the oxidation of resorcin. The recovery of resorcin from sample ranged from 95.2 to 103.4% and the oxidation peak currents were directly proportional to the resorcin concentration from 5.0 × 10⁻⁶ to 1.05 × 10⁻⁴ M with correlation coefficient of 0.9986. A detection limit of 1.0 × 10⁻⁷ M for resorcin was estimated. Various factors affecting the electrocatalytical activity of cobalt hydroxide film were investigated in detail. Real water samples were analyzed and satisfactory results were obtained.     

Theoretical investigation of rotationally inelastic collisions of CH2(X) with helium

Following our earlier work on collisions of He with the methylene radical in its excited ?(1)A(1) state [L. Ma, M. H. Alexander, and P. J. Dagdigian, J. Chem. Phys. 134, 154307 (2011)], we investigate here the analogous relaxation of CH(2) in its ground X(3)B(1) electronic state. The molecule is treated as semi-rigid, with fixed bond lengths but a varying bond angle. We use an ab initio potential energy surface (PES) which is averaged over the CH(2) bending angle weighted by the square of the bending wave function. The PES for the interaction of He with CH(2) in the X state is considerably less anisotropic than for interaction with the ? state since the two 2p electrons on the C atom are evenly distributed among the bonding and non-bonding molecular orbitals. We report quantum scattering calculations of state-to-state and total removal cross sections as well as total removal rate constants at room temperature. Because of the less pronounced anisotropy, these cross sections and rate constants are considerably smaller than for collisions of CH(2)(?) with He. Finally, we investigate the dependence of rotational inelasticity on the bending vibrational quantum number.     

Anderson–Grüneisen parameter for lower mantle region of the Earth under adiabatic condition

A revised model of volume dependence of Anderson–Grüneisen parameter for lower mantle under adiabatic condition is presented in this study, and the volume dependence of (α T/C _P =α ′) is then discussed. It is shown that the results are in good agreement with seismic data of the Earth.     

太赫兹源场致发射电子源

通过粒子模拟(PIC)软件模拟计算了在ps级别下二极与三极结构碳纳米管场致发射的电流密度与电子注聚焦性能。阳极电压在2 kV时,二极结构下电流密度达到1.85 A/cm2;三极结构下,栅压700 V时发射电流密度达到2.3 A/cm2,且在一定的三极结构参数与电极电压下,可以获得较好的电子注聚束效果。通过碳纳米管二极管发射实验,获得了6.6 A/cm2的发射电流密度,总发射电流达到52.1 mA,可以为太赫兹器件提供连续发射的电子注。     

羧甲基纤维素钠/蒙脱土悬浮体系的流变性能及其影响因素

考察了蒙脱土(MT)质量分数(w)、羧甲基纤维素钠(CMC)/MT质量比(R)、电解质(NaCl、MgCl2和AlCl3)、pH值和温度对MT或CMC/MT悬浮体系流变性能和触变性的影响。 结果表明,随w增加,纯MT悬浮体系的流体类型由近牛顿流体向塑型流体变化,触变类型则由无触变、正触变向复合触变性转变;而CMC/MT悬浮体系仍保持MT体系的正触变塑型流体特征,但屈服值τ0和稠度指数K增加,滞后环面积S和电动电势|ζ|先增加后减小,表现出同步变化。 电解质和实验温度均不改变CMC/MT悬浮体系的正触变性塑型流体特征,但电解质使τ0和K增加,而温度增加使τ0和K减小。 随介质pH值的增加,CMC/MT体系由负触变性变为正触变性,|ζ|增大,S先增加后减小,且在pH=8.46时达到最大。     

钯杂多酸/SBA-15的合成及正十六烷的催化氧化

将钯杂多酸锚定在3-氨丙基-三乙氧基硅烷(APTS)修饰的SBA-15孔道内, 得到了一种新型、高效的钯杂多酸/SBA-15 (Pd₃Bi₂W₂₂/SBA-15)多相催化材料. 采用XRD和FT-IR红外光谱对催化剂进行了表征, 并检测了其对正十六烷氧化的催化性能. 结果表明, 以空气为氧化剂, 在无任何溶剂的条件下, 该催化剂对正十六烷烃氧化成醇类和酮类显示出了优良的催化性能, 并且可多次回收利用.     

新型不锈钢基二氧化铅-碳化钨复合电极材料的研制

在不锈钢基上通过复合电沉积的方式制备了二氧化铅 碳化钨（PbO2-WC）电极。 考察了温度、电流、WC颗粒浓度对电极性能的影响;通过析氧曲线、Tafel曲线、扫描电子显微镜能谱、X射线衍射图谱考察了WC颗粒掺杂前后PbO2电极相关性能的变化。 结果表明,在最佳工艺即温度70 ℃、镀液中WC颗粒浓度为40 g/L时,电流密度为0.015～0.025 A/cm2;PbO2-WC共沉积过程中PbO2发生了择优生长,WC颗粒的加入能够细化PbO2晶粒,使镀层变得致密,相对于PbO2电极,PbO2-WC复合电极的耐腐蚀性上升,析氧过电位下降。     

锂离子电池正极材料LiV3O8-xClx的低温固相法合成及电化学性能研究

采用低温固相法成功地合成了锂离子电池正极材料LiV3O8-xClx (x=0.00,0.05,0.10,0.15)。分别用XRD、SEM、充放电实验、循环伏安、交流阻抗等测试方法研究了Cl- 的掺入对LiV3O8结构、形貌及电化学性能的影响。结果表明, Cl-的掺入显著地提高了材料的充放电循环性能。当掺杂量 x=0.10时,材料的循环性能最好, 循环100周后放电容量仍为198.6 mAh/g。