MOF衍生的分层多孔三维N-CoPx/Ni2P大电流密度下加速析氢

氢气(H2)具有能量密度高、环境友好等优点,是一种很有前景的清洁能源载体.目前,电催化水裂解大规模制氢被认为是一种理想可行的方法.析氢反应(HER)涉及多个步骤,首先形成吸附的氢(Volmer步骤),然后是脱附步骤(Heyrovsky步骤)或两个相邻的吸附氢形成H2(Tafel步骤).与酸性介质相比,碱性介质中的HER...     

FeMn掺杂AlN薄膜的制备及其特性研究

采用直流磁控共溅射技术, 以Ar与N₂为源气体, 硅片为衬底成功地制备了Fe, Mn掺杂AlN薄膜. 利用X射线衍射和拉曼光谱研究了工作电流、靶基距离等工艺参数的改变对薄膜结构的影响. 利用扫描电子显微镜和能谱分析仪对薄膜的表面形貌和组成成分进行了分析. 利用振动样品磁强计在室温下对Fe, Mn掺杂AlN薄膜进行了磁性表征. Mn掺杂AlN薄膜表现出顺磁性的原因可能是由于Mn掺杂浓度较高, 在沉积过程部分Mn以团簇的形式存在, 反铁磁性的Mn团簇减弱了体系的铁磁交换作用. Fe掺杂AlN薄膜表现出室温铁磁性, 这可能是AlFeN三元化合物作用的结果. 随着Fe 掺杂AlN薄膜中Fe原子浓度从6.81%增加到16.17%, 其饱和磁化强度M_s由0.27 emu·cm^-3逐渐下降到0.20 emu·cm^-3, 而矫顽力H_c则由57 Oe增大到115 Oe (1 Oe=79.5775 A/m), 这一现象与Fe离子间距离的缩短及反铁磁耦合作用增强有关. 关键词： 直流磁控共溅射 氮化铝薄膜 结构 磁性     

On the Design of Double‐Ellipsoid Mirror Furnace and its Thermal Characteristics for Floating‐Zone Growth of SrxBa1‐xTiO3 Single Crystals

We have designed a double ellipsoid mirror furnace for floating‐zone crystal growth using lamps with rectangular filaments. Its thermal characteristics were studied using an alumina tube for several system configurations. A simple comparison with a commercial furnace that used cylinder lamps for the heating profile was also conducted. By adjusting lamp orientation and positions, one could modify heating profiles easily. In general, the thermal characteristics of the furnace were consistent with the model's prediction [J. Crystal Growth 173 (1997) 561]. The effects of growth chamber and heat pipe were further illustrated. Furthermore, a suitable system configuration leading to better heating uniformity and lower thermal gradients near the growth interface was found for the floating‐zone growth of Sr_xBa_1‐xTiO₃ single crystals.     

一种新型三角架罗丹明B荧光探针对Cu～（2＋）识别性能研究

设计、合成了一种新颖的三角架结构罗丹明B衍生物（2）.在乙醇-水（8/1,V/V）介质中,用Tris-HCl控制体系pH为6.8,观察到Cu^2＋对化合物2的荧光及紫外-可见吸收增强性能,同时化合物2对Cu^2＋具有较高的选择性响应.选择最大激发和发射波长为557/577nm,测定了探针2（1.00×10^-5mol·L^-1）对Cu^2＋响应的校准曲线,线性范围为0.10～10.00×10^-5mol·L^-1,相关系数R^2=0.9964（n=15）,检出限为1.129×10^-7mol·L^-1,平行测定5次的相对标准偏差（R.S.D.）为2.2%;以557nm为最大吸收波长测定紫外吸收,Cu^2＋响应的浓度线性范围为0.50～25.00×10^-5mol·L^-1,相关系数R^2=0.9948（n=13）,检出限为3.338×10^-7mol·L^-1.     

4‐[N,N‐Bis(2‐cyano­ethyl)­amino]­pyridine

The title compound, 3,3′‐(4‐pyridyl­imino)­di­propane­nitrile, C₁₁H₁₂N₄, has a twofold axis and consists of a pyridine ring head and two cyano­ethyl tails, the three groups being linked by an N atom. The planar geometry around the amino N atom suggests conjugation with the π‐system of the pyridine ring. The mol­ecules are stacked in a layer structure via relatively weak to very weak intermolecular C—H⃛π and C—H⃛N hydrogen‐bond interactions.     

Kr/Xe气体在塑料闪烁体表面的吸附与扩散行为研究

采用基于Compass力场的分子动力学(MD)方法,研究了惰性气体氙(Xe)和氪(Kr)在塑料闪烁体(聚乙烯基对甲苯)的平整和粗糙表面的吸附和扩散行为.由惰性气体吸附曲线的均方根位移(MSD),得到了Xe/Kr气体在聚乙烯基对甲苯表面的扩散系数.研究结果表明,Kr/Xe气体均被稳定地吸附在塑料闪烁体表面,其稳定性随着温度的升高而增加,Xe分子的吸附性强于Kr分子. Kr/Xe气体在聚乙烯基对甲苯表面具有较强的扩散性能,扩散深度随着温度与厚度的增加而增加,最大为22.865?,Kr分子扩散能力强于Xe分子.基底粗糙表面增加了两种惰性气体分子的吸附和扩散.     

A general framework for describing photofission observables of actinides at an average excitation energy below 30 MeV

A reasonable prediction of photofission observables plays a paramount role in understanding the photofission process and guiding various photofission-induced applications, such as short-lived isotope production, nuclear waste disposal, and nuclear safeguards. However, the available experimental data for photofission observables are limited, and the existing models and programs have mainly been developed for neutron-induced fission processes. In this study, a general framework is proposed for characterizing the photofission observables of actinides, including the mass yield distributions (MYD) and isobaric charge distributions (ICD) of fission fragments and the multiplicity and energy distributions of prompt neutrons (n_p) and prompt γ rays (γ_p). The framework encompasses various systematic neutron models and empirical models considering the Bohr hypothesis and does not rely on the experimental data as input. These models are then validated individually against experimental data at an average excitation energy below 30 MeV, which shows the reliability and robustness of the general framework. Finally, we employ this framework to predict the characteristics of photofission fragments and the emissions of prompt particles for typical actinides including ²³²Th, ^{235, 238}U and ²⁴⁰Pu. It is found that the ²³⁸U(γ, f) reaction is more suitable for producing neutron-rich nuclei compared to the ²³²Th(γ, f) reaction. In addition, the average multiplicity number of both n_p and γ_p increases with the average excitation energy.     

四程放大激光系统输出能量稳定性研究

 根据原型装置主放大系统组合式四程放大结构的特点,计算分析了放大过程中注入能量、放大增益及损耗的微小起伏对系统输出能量稳定性的影响。根据原型装置集成实验结果,分析了目前原型装置单路输出能量稳定性水平。研究结果表明：注入能量越大,其变化对输出能量影响越小;小信号增益系数对输出能量的影响明显大于注入能量;系统输出能量稳定性对腔内光学元件的透过率变化要求高于腔外光学元件。在3 ns基频光输出达标点处要使输出能量不稳定性控制在5%以内,注入能量起伏要低于10%,腔内放大片小信号增益系数起伏要低于1%,腔内光学系统损耗起伏要低于2%。     

基于截断δ-冲击模型的不完全维修更换策略

本文在截断δ-冲击模型的基础上,考虑了因系统劣化而导致的冲击失效门限值与维修时间的变化,扩充失效状态,从而提出一种新的截断δ-冲击模型。以最小费用为目标,稳态可用度为约束条件,建立N型更换策略的不完全维修更换策略模型,并给出三种常用冲击到达间隔分布的期望寿命。最后通过算例验证模型的有效性,并对参数进行灵敏度分析。