灵芝酸A对人肝癌细胞的辐射增敏效应的初步研究

本研究旨在初步探讨灵芝酸A(GAA)对人肝癌细胞系HepG2在高LET中子和低LET的γ射线条件下的辐射敏感性的影响及差异。研究中,我们用CCK-8方法检测不同浓度GAA对HepG2增殖抑制作用。选取低浓度(5μmol/L)GAA预处理细胞24 h,分别给予不同剂量的中子辐照或γ射线辐照,分别检测克隆存活率、细胞凋亡和γH2AX蛋白的foci的形成。结果表明:在不加GAA的情况下,高LET中子辐射比低LET的γ射线对细胞产生的凋亡比例高;在添加了GAA后,与未加GAA对照组相比,诱导细胞凋亡的比例明显增加;另外,加GAA处理后,细胞增殖抑制率也随着辐照剂量的增加而增高。即GAA能增加HepG2细胞的辐射敏感性,而在同样GAA剂量下,HepG2细胞对高LET中子辐射比低LET的γ射线更敏感。由此,这项研究说明灵芝酸或可开发成为一种天然辐射增敏剂,从而为癌症特别是肝癌的放疗提供新的辅助治疗方法。     

GaInP/GaAs/Ge三结太阳电池不同能量质子辐照损伤模拟

以GaInP/GaAs/Ge三结太阳电池为研究对象,开展了能量为0.7, 1, 3, 5, 10 MeV的质子辐照损伤模拟研究,建立了三结太阳电池结构模型和不同能量质子辐照模型,获得了不同质子辐照条件下的I-V曲线,光谱响应曲线,结合已有实验结果验证了本文模拟结果,分析了三结太阳电池短路电流、开路电压、最大功率、光谱响应随质子能量的变化规律,利用不同辐照条件下三结太阳电池最大输出功率退化结果,拟合得到了三结太阳电池最大输出功率随位移损伤剂量的退化曲线.研究结果表明,质子辐照会在三结太阳电池中引入位移损伤缺陷,使得少数载流子扩散长度退化幅度随质子能量的减小而增大,从而导致三结太阳电池相关电学参数的退化随质子能量的减小而增大.相同辐照条件下,中电池光谱响应退化幅度远大于顶电池光谱响应退化幅度,中电池抗辐照性能较差,同时中电池长波范围内光谱响应的退化幅度比短波范围更大,表明中电池相关电学参数的退化主要来源于基区损伤.     

Highly efficient perovskite solar cells by tuning electronic structures of thienothiophene-based as hole transport materials

The atomic substitutions were used to study the hole transport materials (HTM) properties of six thiophenothiophene molecules (HTM1-HTM6) to reveal the relationship between their core structures and photoelectric properties. To better investigate the difference between experimentally original and designed molecules, we calculated the hole mobility and some parameters (such as energy levels, stability, and optical properties, etc). The results showed that the molecular orbital levels of the original and designed molecules have well matched with perovskite and Ag electrode to ensure hole transport and inhibit the electron reflux. Among the designed HTMs, HTM5 has the smallest energy gap that results in the red-shifted absorption spectra. Furthermore, there is an obviously increased charge transfer integral V due to the introduction of the Si atom, which greatly improved the hole mobility. Therefore, atom substitution by introducing Si atoms (HTM5) will improve the energy levels and charge transport ability, and molecular design by means of atom substitution can be a potential way to tunable HTM performance in solar cells.     

熵的一种通俗教法

熵如力、能量和动量一样是物理学中一个重要概念,若能用一种通俗易懂的方法设计熵的教学,对文科物理的教学有重要意义.为此本文提出了一种通俗的熵的教法,这一教法不需要学生学习热力学第二定律也可以建立熵的概念.具体教学设计如下:通过日常生活例子引入熵的概念(也就是玻尔兹曼熵),设计两个例子让学生会计算熵,通过具体问题的讨论让学生充分理解熵的意义,通过一个实例由玻尔兹曼熵引入克劳修斯熵公式,设计一个演示实验强化教学效果,将熵与环境保护联系起来融入人文情怀,最后还强调了熵计算的不同层次.教学设计完全采用基于问题学习(PBL)的教学模式.     

Fractal behavior in trapping and reaction: A random walk study

We investigate the trapping of a random walker in fractal structures (Sierpinski gaskets) with randomly distributed traps. The survival probability is determined from the number of distinct sites visited in the trap-free fractals. We show that the short-time behavior and the long-time tails of the survival probability are governed by the spectral dimensiond. We interpolate between these two limits by introducing a scaling law. An extension of the theory, which includes a continuous-time random walk on fractals, is discussed as well as the case of direct trapping. The latter case is shown to be governed by the fractal dimensiond.     

Nanoparticulate materials and regulatory policy in Europe: An analysis of stakeholder perspectives

The novel properties of nanoparticulate materials (NPM) and the rapid development of NPM based products have raised many unanswered questions and concerns by different stakeholders over its consequences for the environment and human health. These concerns have led to an increasing discussion in both the US and Europe about possible regulatory policies for NPM. In this article a comparative study of stakeholders’ perceptions on regulatory policy issues with NPM in Europe is presented. It was found that industry wants to regulate this area if the scientific evidence demonstrates that NPM are harmful, but also that the regulatory bodies do not find it necessary at this point of time to regulate until scientific evidence demonstrates that NPM are harmful. This research therefore shows that there will most likely not be any regulatory interventions until there is an established and convincing scientific knowledge base demonstrating that NPM can be hazardous. It is furthermore discussed in this article the different roles and responsibilities of the stakeholders in financing the research required to establish the necessary level of fundamental scientific evidence. It was also found that the activity of the regulatory bodies on this issue differ between the European countries.     

Comparison of theoretical and experimental results for band-gap-graded CZTSSe solar cell

The simulation of CZTSSe solar cells is presented in this paper. The simulation results are in reasonable agreement with the experimental data, indicating the reliability of simulation results. New structure is proposed to increase the functionality of the cell. Improved functional performances are achieved by inserting a P-Silicon (P-Si) layer as back surface field. Simulation results suggest that by inserting this P-Si layer, efficiency of the CZTSSe solar cell increases from 12.6% to 16.59%, which is a significant improvement. For the champion cell J_SC = 36.27 mA/cm², V_OC = 0.625 V and FF = 73.11% has been achieved.     

Extremely low surface recombination in 1 Ω cm n‐type monocrystalline silicon

A key requirement in the recent development of highly efficient silicon solar cells is the outstanding passivation of their surfaces. In this work, plasma enhanced chemical vapour deposition of a triple layer dielectric consisting of amorphous silicon, silicon oxide and silicon nitride, charged extrinsically using corona, has been used to demonstrate extremely low surface recombination. Assuming Richter's parametrisation for bulk lifetime, an effective surface recombination velocity S_eff = 0.1 cm/s at Δn = 10¹⁵ cm^–3 has been obtained for planar, float zone, n ‐type, 1 Ω cm silicon. This equates to a saturation current density J_0s = 0.3 fA/cm², and a 1‐sun implied open‐circuit voltage of 738 mV. These surface recombination parameters are among the lowest reported for 1 Ω cm c‐Si. A combination of impedance spectroscopy and corona‐lifetime measurements shows that the outstanding chemical passivation is due to the small hole capture cross section for states at the interface between the Si and a‐Si layer which are hydrogenated during nitride deposition. (© 2016 The Authors. Phys. Status Solidi RRL published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

阳极界面修饰对钙钛矿太阳能电池性能的影响

采用在聚(3,4-乙撑二氧噻吩)∶聚苯乙烯磺酸(Poly(3,4-ethylenedioxythiophene)∶Poly(styrenesulfonate),PEDOT∶PSS)阳极界面层上直接旋涂二甲基亚砜(Dimethyl Sulfoxide,DMSO)的方法,对PEDOT∶PSS薄膜进行修饰,以提高所制得的钙钛矿太阳能电池器件性能.在5000rpm转速条件下旋涂DMSO后,器件的能量转换效率达到11.43%,与PEDOT∶PSS阳极界面层未做任何修饰的器件相比,效率提高了29.15%.测试表征了修饰前后PEDOT∶PSS薄膜的透光性、表面形貌、电导率、器件的外量子效率曲线以及器件在光照和暗态下的J-V特性曲线,分析了器件性能提高的原因.结果表明:经过修饰的PEDOT∶PSS薄膜导电性显著增强,从而更加有利于器件阳极对空穴的抽取和收集;较未修饰时,器件的短路电流密度得到了大幅度提升,进而使得器件获得更高的能量转换效率.