求解带自由面渗流问题移动网格法的改进及其工程应用

采用有限元固定网格和移动网格相结合的方法,求解带自由面的坝体稳定渗流问题。本方法是针对一般坝体的结构,在有限元网格生成之后,又自动生成了网格移动所需的信息,实现了网格在迭代计算中随自由面的变化自动均匀移动;讨论了网格奇异的不同类型,提出了避免单元形状怪异的移动网格方法;在欧拉空间中分区记录坝体不同的渗透性能,在网格移动到新位置后,自动识别网格所在的物性空间,从而确定单元在新位置上的渗流系数。本文将该方法应用到吉林丰满混凝土重力坝防渗加固的实际工程当中,在考虑大坝原有防渗措施的前提下,利用数值分析,研究了防渗芯墙对大坝渗流性能的影响。计算结果表明,加芯墙后坝体自由面位置明显下移,湿水部分大为减少,坝基扬压力没有明显提升,下游出水点位置没有明显下降。计算过程表明,本文方法及措施具有很好的收敛性与稳定性,且收敛性与自由面初始位置的选择无关。     

Benzothiadiazole-based Conjugated Polymers for Organic Solar Cells

Benzothiadiazole(BT) is an electron-deficient unit with fused aromatic core, which can be used to construct conjugated polymers for application in organic solar cells(OSCs). In the past twenty years, huge numbers of conjugated polymers based on BT unit have been developed,focusing on the backbone engineering(such as by using different copolymerized building blocks), side chain engineering(such as by using linear or branch side units), using heteroatoms(such as F, O and S atoms, and CN group), etc. These modifications enable BT-polymers to exhibit distinct absorption spectra(with onset varied from 600 nm to 1000 nm), different frontier energy levels and crystallinities. As a consequence, BT-polymers have gained much attention in recent years, and can be simultaneously used as electron donor and electron acceptor in OSCs, providing the power conversion efficiencies(PCEs) over 18% and 14% in non-fullerene and all-polymer OSCs. In this article, we provide an overview of BTpolymers for OSCs, from donor to acceptor, via selecting some typical BT-polymers in different periods. We hope that the summary in this article can invoke the interest to study the BT-polymers toward high performance OSCs, especially with thick active layers that can be potentially used in large-area devices.     

Rapid Detection of Five Estrogens Added Illegally to Dietary Supplements by Combining TLC with Raman Imaging Microscope

Estrogens added illegally to dietary supplements are hazardous to human health. Traditional detection and analysis methods have many limitations, and we have developed an assay that combines thin-layer chromatography with Raman imaging microscopy (TLC-RIM). The five estrogens (estrone, estradiol, estriol, ethinyl estradiol, and diethylstilbestrol) were initially separated by TLC, then detected by area scanning Raman imaging with a 532 nm laser under a microscope. Raman spectra were obtained for each estrogen, which were used for detecting estrogen illegally added to botanical dietary supplements. The LOD of each estrogen was 0.4, 1.0, 0.8, 0.2, and 0.2 mg/mL, respectively. The matrix in the real sample did not interfere with the detection of estrogens. The method was fast, sensitive, stable, specific, and reliable.     

The Potential Antidepressant Action of Duloxetine Co-Administered with the TAAR1 Receptor Agonist SEP-363856 in Mice

Here, we explored the possible interaction between duloxetine and SEP-363856 (SEP-856) in depression-related reactions. The results showed that oral administration of duloxetine showed powerful antidepressant-like effects in both the forced swimming test (FST) and the suspension tail test (TST). SEP-856 orally administered alone also exerted an antidepressant-like effect in FST and TST, especially at doses of 0.3, 1, and 10 mg/kg. In addition, duloxetine (15 mg/kg) and SEP-856 (15 mg/kg) both showed antidepressant-like effects in the sucrose preference test (SPT). Most importantly, in the above experiments, compared with duloxetine alone, the simultaneous use of duloxetine and SEP-856 caused a more significant antidepressant-like effect. It is worth noting that doses of drug combination in FST and TST did not change the motor activities of mice in the open-field test (OFT). Thus, duloxetine and SEP-856 seem to play a synergistic role in regulating depression-related behaviors and might be beneficial for refractory depression.     

Pressure dependence of the thermal stability in LiMn2O4

Structural stability in terms of the decomposition temperature in LiMn₂O₄ was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn₂O₄ was found to have structural stability up to 5 GPa at room temperature.Under ambient pressure,the compound decomposed at 1300℃.The decomposition temperature decreased with increasing pressure,yielding more complex decomposed products.Below the decomposition temperature,the crystal structure of LiMn₂O₄ varied with pressure.The presented results in this study offer new insights into the thermal and pressure stability of LiMn₂O₄ materials as a cathode for lithium-ion batteries that can operate under extreme conditions.Therefore,these findings may serve as a useful guide for future work for improving lithium-ion batteries.     

AlmNin (m+n=2–4)二元合金团簇结构和稳定性的密度泛函研究

在密度泛函理论的B3PW91水平上, 优化计算了AlmNin (m+n=2–4)团簇的几何结构、团簇基态的结合能、最高占据轨道与最低空轨道之间的能级间隙和可能的分离能. 结果表明, 随着团簇尺寸的增加, 能级间隙呈现奇偶振荡规律; Al2Ni2团簇具有最高的结合能, 易分离成Ni原子和Al2Ni团簇; 含Al的合金团簇最易先分离出一个Al原子, 而含Ni的合金团簇没有这种趋势.     

Observation of Nano-Dots on HOPG Surface Induced by Highly Charged Arq+ Impact

Highly charged ions （HCIs） have huge potential energy due to their high charge state. When a HCI reaches a solid surface, its potential energy is released immediately on the surface to cause a nano-scale defect. Thus, HCIs are expected to be useful for solid-surface modifications on the nano-scale. We investigate the defects on a highly oriented pyrolytic graphite （HOPG） surface induced by slow highly charged Ar^q＋ ions with impact energy of 20-2000qeV with scanning probe microscopy （SPM）. In order to clarify the role of kinetic and potential energies in surface modification, the nano-defects are characterized in lateral size and height corresponding to the kinetic energy and charge state of the HCIs. Both the potential energy and kinetic energy of the ions may influence the size of nano-defect. Since potential energy increases dramatically with increasing charge state, the potential energy effect is expected to be much larger than the kinetic energy effect in the case of extremely high charge states. This implies that pure surface modification on the nano-scale could be carried out by slow highly charged ions. The mean size of nano-defect region could also be controlled by selecting the charge state and kinetic energy of HCI.     

A Simple Hydrothermal Method for the Growth of ZnO Crystals

ZnO microstructures have been grown from zinc chloride (ZnCl₂) and ammonia solution at 100 °C for 1 – 24 hours. X‐ray diffraction, scanning electron microscope and field‐emission scanning microscope were utilized to investigate the structural properties and morphology of the ZnO crystals. Structural investigations show that phase‐pure hexagonal structure ZnO has been successfully synthesized, and the hexagonal structure ZnO can be achieved in solutions with an appropriate range of concentrations. Under our experimental conditions, several different morphologies of ZnO structures were obtained, including flower‐like and bar flower‐like. The relationship between the morphology and experimental conditions are discussed.     

丝电爆过程的电流导入机理

丝电爆制备纳米粉时, 电流从电极导入金属丝的过程直接影响电极烧损和粉末中微米级大颗粒产生. 分别通过接触和气体放电两种方式导入电流进行电爆试验. 结果表明, 光测量装置检测到的丝端部光电流几乎与回路放电电流同时产生, 而中间位置的光电流则要滞后一段时间; 由探针收集的产物确定, 金属丝端部主要形成熔融粒子, 中间部分主要形成气相粒子. 分析可知, 接触方式导入电流时, 丝端部也存在气体放电现象, 大电流主要通过气体放电形成的等离子体导入. 等离子体对电流的旁路作用会阻碍能量向金属丝沉积, 这是产生微米级大颗粒和"积瘤"主要原因. 通过气体放电方式导入电流时, 电极烧损明显减轻, 并可以避免"积瘤"产生.     

Research on surface photovoltage spectroscopy for GaAs photocathodes with AlxGa1-xAs buffer layer

Surface photovoltage spectroscopy equations for cathode materials with an AlxGa1-x As buffer layer are determined in order to effectively measure the body parameters for transmission-mode (t-mode) photocathode materials before Cs-O activation.Body parameters of cathode materials are well fitted through experiments and fitting calculations for the designed AlxGa1-x As/GaAs structure material.This investigation examines photo-excited performance and measurements of body parameters for t-mode cathode materials of different doping structures.It also helps study various doping structures and optimize structure designs in the future.