Synergistic Effect of Boron Nitride and Carbon Domains in Boron Carbide Nitride Nanotube Supported Single-Atom Catalysts for Efficient Nitrogen Fixation

Developing the low-cost and efficient single-atom catalysts (SACs) for nitrogen reduction reaction (NRR) is of great importance while remains as a great challenge. The catalytic activity, selectivity and durability are all fundamentally related to the elaborate coordination environment of SACs. Using first-principles calculations, we investigated the SACs with single transition metal (TM) atom supported on defective boron carbide nitride nanotubes (BCNTs) as NRR electrocatalysts. Our results suggest that boron-vacancy defects on BCNTs can strongly immobilize TM atoms with large enough binding energy and high thermal/structural stability. Importantly, the synergistic effect of boron nitride (BN) and carbon domains comes up with the modifications of the charge polarization of single-TM-atom active site and the electronic properties of material, which has been proven to be the essential key to promote N₂ adsorption, activation, and reduction. Specifically, six SACs (namely V, Mn, Fe, Mo, Ru, and W atoms embedded into defective BCNTs) can be used as promising candidates for NRR electrocatalysts as their NRR activity is higher than the state-of-the art Ru(0001) catalyst. In particular, single Mo atom supported on defective BCNTs with large tube diameter possesses the highest NRR activity while suppressing the competitive hydrogen evolution reaction, with a low limiting potential of −0.62 V via associative distal path. This work suggests new opportunities for driving NH₃ production by carbon-based single-atom electrocatalysts under ambient conditions.     

Directing the Selectivity of CO Electrolysis to Acetate by Constructing Metal-Organic Interfaces

Electrochemically converting CO₂ to valuable chemicals holds great promise for closing the anthropogenic carbon cycle. Owing to complex reaction pathways and shared rate-determining steps, directing the selectivity of CO₂/CO electrolysis to a specific multicarbon product is very challenging. We report here a strategy for highly selective production of acetate from CO electrolysis by constructing metal-organic interfaces. We demonstrate that the Cu-organic interfaces constructed by in situ reconstruction of Cu complexes show very impressive acetate selectivity, with a high Faradaic efficiency of 84.2 % and a carbon selectivity of 92.1 % for acetate production, in an alkaline membrane electrode assembly electrolyzer. The maximum acetate partial current density and acetate yield reach as high as 605 mA cm⁻² and 63.4 %, respectively. Thorough structural characterizations, control experiments, operando Raman spectroscopy measurements, and density functional theory calculation results indicate that the Cu-organic interface creates a favorable reaction microenvironment that enhances *CO adsorption, lowers the energy barrier for C−C coupling, and facilitates the formation of CH₃COOH over other multicarbon products, thus rationalizing the selective acetate production.     

正已醇-邻、间、对二甲苯二元系固液相平衡

Melting temperatures have been measured and the solid-liquid phase diagrams constructed for 1-hexanol＋o-xylene, 1-hexanol＋m-xylene and 1-hexanol＋p-xylene. They are simple eutectic systems. Excess mole Gibbs free energies were calculated at 298.15K, showing larger positive deviations from ideal-solution behavior. The largest values of GmE are 711、 650 and 800 J•mol-1 for {o-C6H4(CH3)2＋C6H13OH}、 {m-C6H4(CH3)2 ＋ C6H13OH} and {p-C6H4(CH3)2＋C6H13OH} respectively.     

改进型甲醇合成催化剂NC208的催化特性

采用ＴＰＤ、ＸＲＤ、ＢＥＴ和Ｈ２Ｓ中毒试验等方法，对比研究三组份（Ｃｕ－Ｚｎ－Ａｌ）甲醇合成催化剂Ｃ２０７和添加少量金属氧化物的改进型催化剂ＮＣ２０８．结果表明，工作态ＮＣ２０８催化剂表面Ｃｕ＋／Ｃｕ０的比值和价态稳定性大于Ｃ２０７．     

直链单烯烃保留指数与分子结构关系的研究

根据同系直链单烯烃保留指数与同碳数正构烷烃保留指数差值与分子碳数间关系曲线拟合,提出预测同系直链单烯烃保留指数的准确公式。在ＳＱ,ＰＦＥ,ＰＥＧ－４０００上,利用所提出的公式对检验集中化合物保留指数预测值与实测值差的标准偏差在±０．９ｉ．ｕ．～±１．５ｉ．ｕ．之间。并且研究发现,同碳数、同几何构型直链单烯烃各位置异构体分子中双键位置与化合物保留指数具有指数关系。首次提出依据分子中双键位置预测其保留指数的准确公式。公式适合各种不同极性固定相。     

The Armstrong–Frederick cyclic hardening plasticity model with Cosserat effects

We propose an extension of the cyclic hardening plasticity model formulated by Armstrong and Frederick which includes micropolar effects. Our micropolar extension establishes coercivity of the model which is otherwise not present. We study then existence of solutions to the quasistatic, rate-independent Armstrong–Frederick model with Cosserat effects which is, however, still of non-monotone, non-associated type. In order to do this, we need to relax the pointwise definition of the flow rule into a suitable weak energy-type inequality. It is shown that the limit in the Yosida approximation process satisfies this new solution concept. The limit functions have a better regularity than previously known in the literature, where the original Armstrong–Frederick model has been studied.     

A smoothing and regularization Broyden-like method for nonlinear inequalities

In this paper, we consider the smoothing and regularization Broyden-like algorithm for the system of nonlinear inequalities. By constructing a new smoothing function $\phi(\mu,a)=\frac{1}{2}(a+\mu(\ln2+\ln(1+\cosh\frac{a}{\mu})))$ , the problem is approximated via a family of parameterized smooth equations H(μ,ε,x)=0. A smoothing and regularization Broyden-like algorithm with a non-monotone linear search is proposed for solving the system of nonlinear inequalities based on the new smoothing function. The global convergence of the algorithm is established under suitable assumptions. In addition, the smoothing parameter μ and the regularization parameter ε in our algorithm are viewed as two different independent variables. Preliminary numerical results show the efficiency of the algorithm and reveal that the regularization parameter ε in our algorithm plays an important role in numerical improvement, hence, our algorithm seems to be simpler and more easily implemented compared to many previous methods.     

Observation and analysis of near-surface atmospheric aerosol optical properties in urban Beijing

Year-round measurements of the mass concentration and optical properties of fine aerosols(PM_2.5) from June 2009 to May 2010 at an urban site in Beijing were analyzed.The annual mean values of the PM_2.5 mass concentration,absorption coefficient（Ab）,scattering coefficient（Sc） and single scattering albedo（SSA）at 525 nm were 67±66μg/m³,64 ±62 Mm^-1,360 ±405 Mm^-1 and 0.82 ±0.09,respectively.The bulk mass absorption efficiency and scattering efficiency of the PM_2.5 at 525 nm were 0.78 m²/g and 5.55 m²/g,respectively.The Ab and Sc showed a similar diurnal variation with a maximum at night and a minimum in the afternoon,whereas SSA displayed an opposite diurnal pattern.Significant increases in the Ab and Sc were observed in pollution episodes caused by the accumulation of pollutants from both local and regional sources under unfavorable weather conditions.Aerosol loadings in dust events increased by several times in the spring,which had limited effects on the Ab and Sc due to the low absorption and scattering efficiency of dust particles.The frequency of haze days was the highest in autumn because of the high aerosol absorption and scattering under unfavorable weather conditions.The daily PM_2.5concentration should be controlled to a level lower than 64 μg/m³ to prevent the occurrence of haze days according to its exponentially decreased relationship with visibility.     

Existence and multiplicity of systems of Kirchhoff‐type equations with general potentials

This paper is concerned with the following systems of Kirchhoff‐type equations: Under more relaxed assumptions on V(x) and F(x,u,v), we first prove the existence of at least two nontrivial solutions for the aforementioned system by using Morse theory in combination with local linking arguments. Then by using the Clark theorem, the existence results of at least 2k distinct pairs of solutions are obtained. Some recent results from the literature are extended. Copyright © 2016 John Wiley & Sons, Ltd.     

A first regularity result for the Armstrong–Frederick cyclic hardening plasticity model with Cosserat effects

The purpose of this article is to prove the Hölder continuity up to the boundary of the displacement vector and the microrotation matrix for the quasistatic, rate-independent Armstrong–Frederick cyclic hardening plasticity model with Cosserat effects. This model is of non-monotone and non-associated type. In the case of two space dimensions we use the hole-filling technique of Widman and Morrey's Dirichlet growth theorem.