Determination of the 129I transmutation rate and 129I(n, 2n)128I correction using gas mass spectrometry

Two groups of ¹²⁹I and ¹²⁷I targets were analyzed using a gas quadrupole mass spectrometer (QMS) to determine the transmutation rates via the melting method. Sodium iodide was chosen to make the target. The iodine composition in the ¹²⁹I targets is 82.7% ¹²⁹I and 17.3% ¹²⁷I. The transmutation rate of the ¹²⁹I(n, γ)¹³⁰I reaction was determined by measuring the ¹³⁰Xe with QMS. An equivalent corrective method was brought out to correct the ¹²⁹I(n, 2n)¹²⁸I branch which is interfered with by the ¹²⁷I(n, γ)¹²⁸I reaction. And the correction formula was deduced in theory. For very little ¹²⁸Xe from the ¹²⁹I(n, 2n)¹²⁸I reaction, the equivalent corrective method could not be suitable here. However, it is suitable for the mass of ¹²⁸Xe from ¹²⁹I(n,2n)¹²⁸I reaction that reaches the accurately detective level of the mass spectrometry.     

STUDY OF OPTIMAL OPERATING FOR HYBRID GROUND-SOURCEHEAT PUMP SYSTEM IN WUHAN

针对武汉地区混合式热泵系统在运行时出现的热积累现象,利用Fluent软件建立武汉地区某办公楼的冷却塔-土壤源热泵模型,并在传统的温差控制策略的基础上提出两种控制策略——夜间冷却塔运行策略和夜间热泵制热工况运行策略.通过模拟研究,比较3种控制策略的优缺点,发现夜间热泵制热工况运行的控制策略可对土壤起到较好的降温作用,可有效解决系统长期运行热积累的问题.     

Multi-scale modeling and simulation of crystallization during cooling in short fiber reinforced composites

To explore the crystallization during the cooling stage in short fiber reinforced composites, a multi-scale model in which macroscopic temperature and microscopic crystal morphology are related with each other is built up. According to this multi-scale model, the algorithm of coupling finite volume method with pixel coloring method is proposed. The finite volume method is used on the coarse grid to calculate the macroscopic temperature and the pixel coloring method is employed on the fine grid to capture the morphology of crystallization. Roles of cooling rate, initial temperature as well as the nucleation rate per unit fiber surface are investigated. To our knowledge this is the first time that a fully coupled multi-scale model and a multi-scale algorithm have been applied to the crystallization of short fiber reinforced composites.     

Synergistic effect of La and Co co-doping on room-temperature ferromagnetism enhancement of TiO2 nanoparticles

The synergistic influence of lanthanum and cobalt co-doping on room temperature ferromagnetism (RTFM) of TiO₂ system is investigated. A series of Ti_0.97?xCo_0.03La_xO₂ nanoparticles were prepared and their structures and properties were systematically studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, UV–vis spectrophotometer, Raman spectra and magnetic measurement techniques, respectively. Detailed experimental characterizations indicate that the as-prepared La and Co co-doped samples exhibit single anatase phase, and all the samples exhibit strong visible photoluminescence associated with oxygen vacancies and a clear ferromagnetic hysteresis loop, both of which were dramatically enhanced with La and Co co-doping, and the maximum saturation magnetization (M_s) reaches 1.38 emu/g at the La content of 6 mol%. It is speculated that oxygen vacancies modulated by ionic La play an important role in the enhanced RTFM, which can be attributed to the bound magnetic polarons (BMPs) formed via ferromagnetic coupling between two neighboring Co²⁺ ions mediated by oxygen vacancy (F⁺ center). Our results present an alternative method to obtain high performance RTFM.     

The anti-tumor effects of cordycepin-loaded liposomes on the growth of hepatoma 22 tumors in mice and human hepatoma BEL-7402 cells in culture

Liposomes have successfully been used for decades to encapsulate and protect drugs that are prone to deactivation in the body. The present study aimed to demonstrate the use of liposomes to encapsulate cordycepin, an adenosine analog that quickly loses its activity in vivo. The cordycepin-loaded liposomes were prepared by the ammonium sulfate gradient approach, and its in vitro and in vivo antitumour activities were evaluated using BEL-7402 cells and hepatocellular carcinoma H22 transplanted tumors, respectively. An MTT assay was used to observe the cytotoxicity of cells treated with cordycepin and cordycepin-loaded liposomes in vitro. High-content screening (HSC) was carried out using Hoechst 33342 to detect apoptotic cells and the ratio of cells in different cell cycle stages. The data demonstrated that both the cordycepin and the cordycepin-loaded liposomes resulted in clear cytotoxicity with IC50 values of 18.97 and 29.39?μg/mL, respectively. The latter showed significantly strong inhibitory effects on H22 tumor growth in mice, while the former did not show any inhibitory effects on tumor growth. In addition, the HSC assay showed that the cordycepin-loaded liposomes resulted in a higher rate of apoptosis than the cordycepin alone in BEL-7402 cells. Further data analysis revealed that the cells treated with cordycepin-loaded liposomes were predominately arrested at the G2/M phase (p?p?in vivo anti-tumor activity of cordycepin.     

Isomers of dialkyl diketo-pyrrolo-pyrrole: Electron-deficient units for organic semiconductors

Diketo-pyrrolo-pyrrole (DPP) is an important electron-deficient unit, and the alkylation of DPP can gives rise to good solubility of organic and polymer semiconductors in solvent. In this paper, we report our observations on the isomers of dialkyl DPP. The alkylation of DPP can take place on both the nitrogen and oxygen atoms, leading to the formation of three isomers. The presence of the isomers is evidenced by the nuclear magnetic resonance (NMR) and mass spectra. The yields of the isomers are affected by the experimental conditions, including the reaction temperature, reaction time and solvent. The isomers have different electronic structures and optical properties as revealed by the UV–Vis absorption spectroscopy, fluorescent spectroscopy, cyclic voltammetry and theoretical simulation using Gaussian 03 program with B3LYP/6-31G(d). Small molecules based on the DPP isomers with dialkylation at different sites were synthesized and investigated as donor materials of organic solar cells (OSCs). The photovoltaic performances of OSCs are consistent with the electronic structures of the DPP isomers.     

岩质高切坡预应力锚索超前支护研究

采用极限分析上限定理研究遵循Hoek-Brown强度准则岩质高切坡超前支护问题。首先研究无支护岩质高切坡的稳定性,给出无支护岩质高切坡稳定计算方法;其次,分析预应力锚索超前支护岩质高切坡的力学机制,推导相关计算公式和预加固荷载确定方法;最后分析加固岩质高切坡在地震荷载下的临界屈服加速度及其永久位移。揭示了开挖方式、强度参数对预应力锚索加固岩质高切坡的影响。     

岩体质量Q系统计算平台的开发与应用

岩体质量分类Q系统是目前应用最广的岩体质量分类方法之一.为了实时准确地判断岩体稳定性,提高工作效率,并将Q系统岩体分类信息化,以Python为开发语言,利用Web网络技术和数据库技术开发了岩体质量Q系统计算平台.详细介绍了岩体质量Q系统计算平台的开发原理和操作流程,将Q系统与网页界面结合,并通过网页展示Q系统图解与支护...     

High-performance inverted polymer solar cells with lead monoxide-modified indium tin oxides as the cathode

The photovoltaic stability of polymer solar cells (PSCs) can be greatly improved by adopting an inverted device structure. This paper reports high-performance inverted PSCs with lead monoxide (PbO)-modified indium tin oxide (ITO) as the cathodes. A thin PbO layer can effectively lower the work function of ITO from 4.5 to 3.8 eV. The optimal inverted PSCs with poly(3-hexylthiophene) (P3HT) as the donor and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as the acceptor exhibited high photovoltaic performance: open-circuit voltage of 0.59 V, short-circuit current density of 10.8 mA cm⁻², fill factor of 0.632, and power conversion efficiency of 4.00% under simulated AM1.5G illumination (100 mW cm⁻²). The photovoltaic efficiency is significantly higher than that of the control inverted PSCs with unmodified ITO as the cathode. It is even better than that of the control PSCs with normal architecture, which have an optimal efficiency of 3.5%. The lowering in the work function by the PbO modification is attributed to the charge transfer between PbO and ITO, as evidenced by the X-ray photoelectron spectra.