共聚反应的Monte Carlo模拟和竞聚率的概率估算

本文利用Monte Carlo方法模拟了二元共聚反应的链增长过程,并给出了估计竞聚率的概率统计处理。从统计观点上讲,这是一种在参数空间对每个栅格点计算后验概率密度的Bayesian统计,采用平滑函数对不规则的后验概率密度曲面(PPDS)进行平滑化,从而在置信的95尹。区域评价共聚反应竞聚率(r_1,r_2)。本方法用于计算苯乙烯-丙烯酸丁酯二元共聚反应时,所计算的竞聚率(r_(St),r_(BA))与文献结果甚为一致。     

M2@C79N (M = Y, Tb): isolation and characterization of stable endohedral metallofullerenes exhibiting M-M bonding interactions inside aza[80]fullerene cages

Y2@C79N and Tb2@C79N have been prepared by conducting the Kratschmer-Huffman electric-arc process under 20 Torr of N2 and 280 Torr of He with metal oxide-doped graphite rods. These new heterofullerenes were separated from the resulting mixture of empty cage fullerenes and endohedral fullerenes by chemical separation and a two-stage chromatographic process. Crystallographic data for Tb2@C79N x Ni(OEP) x 2 C6H6 demonstrate the presence of an 80-atom cage with idealized I(h) symmetry and two, widely separated Tb atoms inside with a Tb-Tb separation of 3.9020(10) A for the major terbium sites. The EPR spectrum of the odd-electron Y2@C79N indicates that the spin density largely resides on the two equivalent yttrium ions. Computational studies on Y2@C79N suggest that the nitrogen atom resides at a 665 ring junction in the equator on the fullerene cage and that the unpaired electron is localized in a bonding orbital between the two yttrium ions of this stable radical. Thus, the Tb-Tb bond length of the single-electron bond is an exceedingly long metal-metal bond.     

Harnack and Shift Harnack Inequalities for Degenerate (Functional) Stochastic Partial Differential Equations with Singular Drifts

Journal of Theoretical Probability - The existence and uniqueness of the mild solutions for a class of degenerate functional stochastic partial differential equations (SPDEs) are obtained, where...     

Application of Ultrasound Irradiation for the Reactions of N-Hydroxymethylation

A convenient and high yield method for the N-hydroxymethylation of substituted phthalimide and benzimidazole under ultrasound irradiation is reported.     

活性炭载体的微波处理对氨合成催化剂Ru/C催化性能的影响

 将一种商用活性炭在氮气保护下进行微波处理，采用元素分析、XRD、N2物理吸附和CO化学吸附等表征手段，考察了微波处理对活性炭载体的化学组成、物相、表面织构和催化剂钌分散度的影响．以微波处理的活性炭为载体，以钡或钡铯为助剂，制备了一系列钌催化剂，在SV＝10000h－1，p＝10．0MPa和θ＝430℃的条件下进行了氨合成活性评价．结果表明，活性炭经微波处理后能有效地脱除非碳成分，提高炭载体的稳定性，制备的负载型钌催化剂不仅具有较高的钌分散度，而且在一定温度范围内能够防止金属粒子烧结，从而使催化剂的活性和稳定性明显提高．例如，以未经处理的活性炭为载体制备的4％Ru－Ba－Cs／C催化剂，其出口氨浓度为9．23％，经1．0MPa，520℃耐热36h后，其出口氨溶解度下降至7．39％；而以经微波处理的活性炭（CW5）为载体制备的4％Ru－Ba－Cs／CW5催化剂，出口氨浓度为16．78％，经相同条件耐热后，其催化活性基本不变．     

掺铈的锰锑合金电子结构计算

利用原子团模型和DV-xa方法,计算了掺铈的锰锑合金的电子结构和自旋磁矩,首次确定了掺铈合金中锰、锑和铈各原子之间的电荷转移,并与未掺杂的锰锑合金的计算结果进行了比较,结果表明掺铈合金中铈原子有部分电荷转移到锑原子上,讨论了掺铈合金中铈原子的4f轨道的特性,发现铈原子4f轨道有很强的局域性。在Fermi面附近,铈原子的4f轨道与锑原子的5P轨道、锰原子的3d轨道有相互作用,但铈原子与锑原子之间的作用更强。     

Non-linear functional boundary value problem for discontinuous functional differential equations

This paper is devoted to investigating the existence of solutionsfor discontinuous functional differential equations with non-linearfunctional boundary conditions. Some existence results of solutionsare obtained by employing a generalized method of upper andlower solutions, which may be discontinuous.     

一类三阶非线性系统的全局稳定性

运用“类比法”，在文（１）的基础上，构造了一类三阶非线性系统的李雅普诺夫函数给出了该系统零解全局渐近稳定的充分条件，较大推广了文（１）（２）的结果。     

考虑气压效应平流层平台柔性飞艇变形分析方法与特征研究

为研究气压对平流层飞艇变形性能的影响,基于铁木辛柯梁分析理论,将低阻尼流线形飞艇假设为分段等截面充气梁,采用叠加法推导了考虑气压效应的柔性飞艇总体挠度计算式。同时,将柔性飞艇作为预应力薄膜结构,应用ANSYS软件,采用小杨氏模量法进行充气预应力找形,并基于找形结果进行载荷下非线性变形分析。在此基础上计算了飞艇外气囊在不同头部荷载与气压下的总体挠度并比较了两种方法的计算值,发现两者变化趋势一致。最后,建立了25 m验证飞艇的计算模型,得到了控制点应力和总体变形;给出了飞艇下腹线在不同气压下的位形,将其与测量值进行比较表明:计算值和测量值基本相等,误差小于5%。本文对大型柔性飞艇设计分析具有一定的参考价值。     

Dirac Nodal Arc Semimetal PtSn4: An Ideal Platform for Understanding Surface Properties and Catalysis for Hydrogen Evolution

Conductivity, carrier mobility, and a suitable Gibbs free energy are important criteria that determine the performance of catalysts for a hydrogen evolution reaction (HER). However, it is a challenge to combine these factors into a single compound. Herein, we discover a superior electrocatalyst for a HER in the recently identified Dirac nodal arc semimetal PtSn₄. The determined turnover frequency (TOF) for each active site of PtSn₄ is 1.54 H₂ s^?1 at 100 mV. This sets a benchmark for HER catalysis on Pt‐based noble metals and earth‐abundant metal catalysts. We make use of the robust surface states of PtSn₄ as their electrons can be transferred to the adsorbed hydrogen atoms in the catalytic process more efficiently. In addition, PtSn₄ displays excellent chemical and electrochemical stabilities after long‐term exposure in air and long‐time HER stability tests.