Effect of multiple rescattering processes on harmonic emission in spatially inhomogeneous field

The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schr?dinger equation and the classical equation of motion.By establishing the physical model of the harmonic emission in the inhomogeneous field, we discuss the related characters of the multiple rescatterings process in the harmonic generation process. It shows that the second rescattering rather than the first rescattering tends to determine the harmonic cutoff energy when the inhomogeneous parameter is larger than 0.0055.Additionally, with the classical simulation, the underlying physical mechanism of the continuum–continuum harmonics is also revealed. Moreover, this work may provide new physical insight into the harmonic generation in an inhomogeneous field, and is beneficial to further extract the harmonic emission from molecular systems.     

生物阴极微生物燃料电池不同阴极材料产电特性

以葡萄糖(COD初始浓度为2000 mg/L, COD为化学需氧量)为阳极燃料底物, 考察了碳纤维刷和柱状活性碳颗粒作为生物阴极微生物燃料电池(MFC)阴极材料的产电性能. 研究结果表明, 碳纤维刷MFC的启动时间比碳颗粒MFC的长, 达到稳定状态后的恒负载(300 Ω)电压(0.324 V)比碳颗粒阴极MFC的(0.581 V)低. 极化分析结果表明, 碳纤维刷MFC和碳颗粒MFC的最大功率密度分别为24.7 W/m3(117.2 A/m3)和50.3 W/m3(167.2 A/m3). 电化学交流阻抗谱(EIS)测定结果表明, 由于电极材料对微生物生长和分布状态存在不同的影响, 使得碳纤维刷阴极MFC的极化内阻大于碳颗粒阴极MFC的极化内阻.     

Combined experimental and theoretical study on the effect of Nb content on martensitic transformation of NbRu shape memory alloys

The effect of Nb content on the martensitic transformation of NbRu high-temperature shape memory alloys is investigated by experiments and first-principles calculations. We calculate the lattice parameters, density of states, charge density, and heats of formation of Nb_50+xRu_50-x β phase. The results show that an increase in Nb content increases the stability of Nb_50+xRu_50-x β phase, leading to a significant decrease of the β to β' martensitic transformation temperature. In addition, the mechanism of the effects of Nb content on phase stability and martensitic transformation temperature is studied on the basis of electronic structure.     

35MeV/uAr离子辐照聚酯膜引起的效应研究

采用多种手段研究了 35Me V/u的 Ar离子辐照聚酯 (PET)膜产生的微观结构变化 .结果表明 ,辐照使聚酯的化学键断裂并产生了炔端不饱和基团和自由基 .断键主要发生在乙二醇残留物、苯环的对位和酯的 C— O键上 .随着吸收剂量的增加 ,材料的结晶度逐渐降低 ,由原始的41 .7%减至最高辐照量时的 1 5.0 % .研究发现 ,聚脂的非晶化转变截面与电子能损呈线性关系 ;断键和非晶化效应主要取决于样品的吸收剂量 ,并存在一个约 4.0 MGy的阈值.Stacked polyethylene terephthalate films were irradiated with 35 MeV/u Ar ions at room temperature. The ion induced effects were studied by ultraviolet visible spectrometer, Fourier transform infrared spectroscopy, X ray diffractometer, X ray photoelectron spectroscopy, electron spin resonance spectroscopy and differential scanning calorimetry. Bond breaking and the formation of alkyne end groups and free radicals were observed. The bond breaking processes occurred mainly...     

Ar+8轰击石墨表面损伤的扫描隧道显微镜观测研究

报道了用10—112MeV能量的Ar+8离子轰击高定向石墨造成损伤的原子水平观测结果,给出了损伤形貌、损伤大小和损伤数密度.讨论了损伤与表面核能损的关系及损伤过程的可能机制.     

不同能量He离子注入单晶Si引起的损伤研究

40、160和1550 keV能量的He离子在室温下注入单晶Si样品到相同的剂量5×1016 ions/cm2,采用透射电子显微镜(TEM)研究了800℃退火1h在Si中引起的损伤形貌.结果表明,三种能量的He离子注入Si并经高温退火均能产生空腔,但空腔的形貌、尺寸以及分布深度都依赖于离子的能量.结合TRIM程序计算结果对空腔和其它缺陷产生对He离子能量的依赖性进行了讨论.     

响应面优化-气相色谱质谱联用测定食品中山梨酸、苯甲酸和肉桂酸

研究了不同前处理条件对食品中3种防腐剂回收率的影响。在单因素实验基础上,以乙醇用量、浓硫酸用量和衍生温度为影响因素,应用Box-Benhnken响应面优化试验分析3种防腐剂回收率。结果表明,最佳衍生条件:浓硫酸1.0 m L,乙醇2.5 m L,在90℃下衍生15 min。在此条件下,山梨酸、苯甲酸和肉桂酸实测回收率分别为91.8%,90.8%,95.0%,与RSM模型预测值无显著性差异。     

硅—二氧化硅界面过渡区的XPS研究

本文报道了用X射线光电子能谱的角度效应研究硅-二氧化硅界面过渡区的结果。样品为(111)取向的硅单晶片上低温(700℃)氧化生成的超薄氧化膜,膜的厚度不大于50?。氧化膜与单晶衬底中Si_2p光电子谱峰之间的化学位移(δ)和强度比(I_0x/I_si)随光电子发射角(θ)的变化明显地偏离理想界面所预期的结果,表明在硅-二氧化硅的界面处存在化学比为SiO_x(0yO_4-y(0≤y≤4)型四面体。比较实验曲线与随机成键模型的计算结果,估计出过渡区的宽度不大于20?,小于Si_2p光电子在二氧化硅中的平均逃逸深度。对改变氧化时间结合Ar⁺刻蚀制得的氧化膜厚度不同的样品所作的测量,得到与角度实验相一致的结果。 关键词：     

High power CW diode-side-pumped Nd:YAG rod laser

We report on the characterization of a diode-side-pumped Nd:YAG rod laser operating at high CW output power. A four-fold pump configuration is designed and the pump light is directly coupled into the Nd:YAG rod without the help of any cylindrical lenses. The distribution of pump light in the Nd:YAG rod has been calculated by using ray tracing program. The thermal lens effect of the Nd:YAG rod has been experimentally measured. A maximum output power of 800 W at 1064 nm in multimode operation is obtained for a pump power of 2400 W with 33% optical-optical efficiency. At the same time, the maximum beam parameter product of 25 mm·mrad is achieved.     

"问题链·导学"PK"讲授式"

最近在苏中一所四星高中听了两节高一数学新授课,两个教师围绕<向量的加法>展开了两种不同教学模式的同课异构,听后感触颇多,于是写下一些心得体会与大家分享.让我们先来看看两位教师教学设计的基本流程.