4-乙酰基-1,3-二氟苯硝化反应机理研究

以4-氨基-1,3-二氟苯、乙酸酐和浓硝酸等为原料,合成了4-乙酰基-5-硝基-1,3-二氟苯,并且采用FTIR和1H NMR对产物进行了表征.采用量子化学方法,探讨了在酸催化条件下4-乙酰基-1,3-二氟苯硝化反应过程中的微观机理,在密度泛函理论的B3LYP/6-311G**水平下搜索得到反应路径,并对各中间体、过渡态和产物进行几何优化、振动频率分析和标准热力学函数计算;反应路径经过IRC验证.在MP2/6-311G**水平上对所有中间体、过渡态和产物进行更精确的能量计算.     

Functional Dithienopyrazines: Structure-Property Relationships**

Dithienopyrazines are only scarcely used as building blocks in organic electronic materials. Here, we report efficient preparation and investigation of syn- and anti-dithienopyrazines, which were functionalized with triaraylamine units to provide different series of donor-acceptor-donor-type materials. The characterization of the optoelectronic properties resulted in valuable structure-property relationships and allowed for the elucidation of the influence of structural effects such as core structure (syn vs anti), type of substituents (directly arylated vs ethynylated aryl), and substitution pattern (α,α’- vs β,β’- vs fourfold substitution). Finally, first application of a dithienopyrazine derivative as model for hole-transport materials tailored for organic electronic devices has been realized.     

How Doping Affects the Activity of the Aluminum Oxide Support

The performance of heteronuclear clusters [AlXO₃]⁺ (X=Al, AlO₄, AlMg₂O₂, AlZnO, AlAu₂, Mg, Y, VO, NbO, TaO) in activating methane has been explored by a combination of high–level quantum calculations with reported and supplementary gas-phase experiments. With different dopants in [AlXO₃]⁺, the mechanism, reactivity and selectivity towards methane activation varies accordingly. The classic HAT competes with PCET, depending on the composition of intramolecular interactions. Although the existence of terminal oxygen radical is beneficial for classic HAT, the Al_t−C interaction in the [AlXO₃]⁺ clusters as enhanced by the strongly electronegative doping groups (X=Al, AlZnO, Mg, Zn, VO, NbO, TaO) favors the PCET process, facilitating C−H bond breaking. In addition, with different dopants, the destiny of the split methyl group varies accordingly. While strong interaction between Al_t and CH₃ results in the formation of the Al_t−C bond, dopants with variable valance may promote the formation of deep-oxidation products like formaldehyde. It has been discussed in detail how to regulate the activity and selectivity of the active center of the catalyst via rational doping.     

Hetero-Polar Sextuple Bond: A Relativistic Quantum Chemical Study**

Number of bonds formed by sharing an electron pair between two atoms is not restricted to one, it can go beyond four and six is the maximum. While homopolar sextuple bond in Mo₂ and W₂ has been reported, such a high bond order in heteropolar diatomics has remained elusive. In the pursuit of the sextuple bond in polar diatomics, the present study depicts the existence of such multiple bonds in Rhodium-Scandium hetero-diatom based on relativistic quantum chemical calculations. The bonding comprises of three normal electron sharing covalent bonds and three dative covalent bonds.     

Experimental and theoretical studies of carbon monoxide oxidation over W/Cu/Ce trimetallic oxides: the effect of W addition

It is a significant method to prepare highly dispersed polymetallic oxides using in-situ doping metal organic frameworks as precursors. Herein, a series of straw-like W/Cu/Ce trimetallic oxides were prepared by using phosphotungstic ionic liquid@Ce-based metal organic framework adsorbing with copper acetylacetonate as precursors. The effect of W content on catalytic activity of W/Cu/Ce trimetallic oxides for carbon monoxide (CO) oxidation was well-investigated. Comprehensive characterization methods and density functional theory calculations were adopted to reveal the property changes of Cu/CeO₂ catalyst by the addition of W. The results demonstrated that W, Cu, and Ce are highly dispersed in the prepared W/Cu/Ce trimetallic oxides, and adding proper amount of W can improve the activity of the catalyst. H₂ temperature-program reduction profiles, X-ray photoelectron spectroscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy, and density functional theory calculations clearly revealed that after the addition of W, the strength of Ce-O bond is weakened, the oxygen vacancy is increased, and the adsorption of CO is enhanced, respectively, which are vital reasons for its high catalytic activity. In addition, the CO oxidation reaction pathway over prepared W/Cu/Ce trimetallic oxides based on the Mars-van Krevelen mechanism was studied, and the results exhibited that CO can wrest the lattice oxygen of W/Cu/Ce trimetallic oxides to form CO₂, which is also proved to be the rate-determining step in reaction process.     

Numerical analysis of the cooling structure of side-pumped solid laser

针对侧面泵浦固体激光器的强制对流冷却结构,利用CFD软件Ansys Fluent数值分析了在冷却结构中添加分流隔板对流动状况的影响,计算了特定流量时冷却结构的压降,并在该冷却条件下得到增益介质自身的温度分布。计算结果表明:分流隔板对冷却结构整个阻力的影响可以忽略,但对通道内水流状况具有明显的影响,由于板条两侧水流的不对称性以及同一侧水流的不均匀性,导致增益介质自身的温度分布也存在较大的不一致。     

飞秒激光作用下金属箔材的温度场研究

为分析飞秒激光作用下金属材料的温度场及其影响因素,基于一维双温模型对飞秒激光作用下铜箔的温度场进行数值求解。采用脉宽100～800 fs,能量密度509.30～2 546.48 J/m2的激光参数进行计算,研究电子和晶格温度随时间和深度的变化规律。结果表明,电子温度在10-13 s时间尺度达到峰值,在此期间晶格温度保持不变,此后通过耦合作用二者在几ps时间尺度达到热平衡;脉宽越短,电子温升越快、峰值温度越高、耦合时间越短;而能量密度越大,电子温升越快、峰值温度越高、耦合时间越长。     

双门选超声波收发模拟电路的设计

针对现有模拟板中存在冗余的电容导致建波信号拖尾较长,致使超声信号经模拟板处理后分辨率低的问题,提出了一种以差分接收、双门选回波处理硬件电路设计。在检波放大之前设计一个门选电路,直接从全波信号中选取缺陷信号,避免了界面波经过检波放大电路后,形成拖尾淹没缺陷信号,提高了接收电路信号的可靠性。文中从硬件方面介绍了接收电路的调整。实验表明,电路性能稳定、精度高、成本低,并具有良好的应用前景。     

基于“五分法”信令分析的精准化4G市场营销支撑研究

针对目前传统粗犷式4G营销手段存在的营销成本高、效率低的问题,本文从时段、地域、业务习惯、用户套餐、终端等5个维度结合TD-LTE核心网信令分析挖掘手段创新提出“五分法”营销支撑方案,全方位分析用户需求,助力市场一线开展4G精准化营销,提升营销效率,提高市场份额。     

浅谈厂用电继电保护配置与整定的重要性

通过一起火电机组的非停事故,来分析其厂用电继电保护配置与整定存在的问题,提高从业人员对继电保护整定或核算工作的重视性.