An infinite chain, {[Ni(tn)2]3[Fe(CN)4(μ-CN)2]2}n,a new catalyst for electrochemical-driven water splitting and photochemical-driven hydrogen evolution from water under blue light

A new catalyst for both water reduction and oxidation, based on an infinite chain, {[Ni(tn)₂]₃ [Fe(CN)₄ (μ-CN)₂]₂}_n, is formed by the reaction of NiCl₂, 1,3-propanediamine (tn) and K₃ [Fe(CN)₆]. {[Ni(tn)₂]₃ [Fe(CN)₄ (μ-CN)₂]₂}_n can electro-catalyze hydrogen evolution from a neutral aqueous buffer (pH 7.0) with a turnover frequency (TOF) of 1561 mol of hydrogen per mole of catalyst per hour (H₂/mol catalyst/h) at an overpotential (OP) of 837 mV {[Ni(tn)₂]₃ [Fe(CN)₄ (μ-CN)₂]₂}_n also can electro-catalyze O₂ production from water with a TOF of ～45 mol O₂ (mol cat)^?1s^?1 at an OP of 591 mV. Under blue light (λ = 469 nm), together with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H₂A) as a sacrificial electron donor, {[Ni(tn)₂]₃ [Fe(CN)₄ (μ-CN)₂]₂}_n can photo-catalyze hydrogen generation from an aqueous buffer (pH 4.0) with a turnover number (TON) of 11,450 mol H₂ per mole of catalyst (mol of H₂ (mol of cat)^?1) during 10 h irradiation. The average of apparent quantum yield (AQY) is as high as 40.96% during 10 h irradiation. Studies indicate that {[Ni(tn)₂]₃ [Fe(CN)₄ (μ-CN)₂]₂}_n exists in two forms: a cyano-bridged chain ({[Ni(tn)₂]₃ [Fe(CN)₄ (μ-CN)₂]₂}_n) in solid, and a salt ([Ni(tn)₂]₃ [Fe(CN)₆]₂) in aqueous media; Catalytic reaction occurs on the nickel center of [Ni(tn)₂]²⁺, and the introduction of [Fe(CN)₆]^3- can improve the catalytic efficiency of [Ni(tn)₂]²⁺ for H₂ or O₂ generation. We hope these findings can afford a new method for the design of catalysts for both water reduction and oxidation.     

烃类在三甘醇和四甘醇中无限稀释活度系数的测定与关联

用气相色谱法分别测定了苯、甲苯、乙苯、正庚烷、正辛烷、正壬烷和正癸烷在三甘醇和四甘醇中的无限稀释活度系数 ,测定温度范围为 5 0～ 13 0℃。用修正的UNIFAC模型 (Dortmund)对上述不同温度下的无限稀释活度系数实验数据进行关联 ,得到了三甘醇和四甘醇与其它基团的相互作用参数 ,并将计算结果与实测值进行了比较。     

Alternating,all-trans polyenynes: Model compounds for poly(diacetylene)s with defined conjugation length

The syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v_(C?C) = 2108–2128 cm^?1 and v_(C?C) = 1505–1532 cm^?1 were calculated after extrapolation. Similarly sp-C¹³C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data.     

The thermal ignition of lignocellulosics in infinite slab and cubic geometries

Wood shaving samples were heated in both cubic baskets and in a previously described system realising the conditions of the ‘infinite slab’ in thermal ignition. Results from the two sets of experiment were found to be totally consistent with each other.     

二阶曲线渐近线的等价定义及其应用

给出了射影几何中关于二阶曲线渐近线的几个等价定义,并探讨了根据不同 定义的二阶曲线渐近线的应用．     

SYMMETRIC STABLE SEQUENCES WITH MISSING OBSERVATIONS

Abstract. A procedure for evaluating optimal linear estimates of missing values in the minimum dispersion sense is proposed for stationary symmetric stable processes. Analytical expressions for the estimates are obtained for the autoregressive moving-average process and it is shown that the finite variance setting results are special cases. Cases of one and more than one missing value are considered.     

Analysis of a conjugated infinite element method for acoustic scattering

This work is devoted to a study of a conjugated infinite element method for Helmholtz problems in exterior domains. A formulation of this method with Lagrange multipliers defined on (semi-)infinite space is presented and analyzed in a domain decomposition context. The implementation aspects of this method in a parallel industrial acoustic software (SYSNOISE) are described in details. Numerical results show the computational efficiency of this method on acoustic scattering problems.     

Stability of Impulsive Stochastic Neutral Partial Differential Equations With Infinite Delays

In this paper, we study the existence and asymptotic stability in the pth moment of the mild solutions to impulsive stochastic neutral partial differential equations with infinite delays. Sufficient conditions ensuring the stability of the impulsive stochastic system are established. The results are obtained via the Banach fixed point theorem.     

基于事件触发的电力系统H∞优化控制

针对大规模集中用电导致电力系统负荷端激增从而影响电力系统稳定性的问题,提出一种基于事件触发的H_∞优化控制方式。本文采用扇区法对单机无穷大电力系统进行线性化处理,之后通过模糊逻辑建立电力系统的T-S模糊模型。通过事件触发理论和模糊逻辑利用并行分布补偿(parallel distribution compensation,PDC)的方法设计系统控制器。H∞优化控制相比于传统的控制方法提高了系统的稳定性及抗干扰能力,因此本文根据李雅普诺夫稳定性理论和H∞优化控制理论,基于线性矩阵不等式(linear Matrix Inequality,LMI),给出了保证单机无穷大电力系统闭环渐进稳定的充分条件,并采用MATLAB仿真软件对系统进行仿真,从而证明稳定条件的存在。     

预分离色谱法直接测定微量组份无限稀释活度系数

预分离色谱法可直接测定混合物中微量组份的无限稀释活度系数(γ~∞),而不必把此组份从混合物中分离出来。主要由四步组成:被测组份的预浓缩,被测组份的定性,选择预分离柱和γ~∞的测定。预浓缩样品经过预分离柱分出被测组份,然后进入测量柱测定γ~∞。此方法简捷、可靠与常规以纯溶质进样的色谱测y~∞的方法具有相同的测定精度,可广泛用于缺少纯样的场合。用此法测定了戊烯-1-炔-4、丁炔-2在若干酸醇中的γ~∞,分别求得了修正和未修正的UNlFAC参数,对kikic修正模型其值为ac=c,CooH=694.9(K)acooH,c=c=-99.08(K),ac=c,oH=812.99(K),aoH,c=c=143.36(K)