关于三次方幂补数的均值

设n是正整数，s(n)为n的三次方幂补数．本文的主要目的是研究s(n)的均值分布性质，解决文[2]中F．Smarandache教授提出的第28个问题，给出了一个有趣的渐近公式。     

可见光催化醛、酮或亚胺与缺电子芳烃还原偶联构筑芳基取代醇和胺（英文）

通过C=X(X=O,N)双键极性翻转构筑碳-碳键是有机化学反应的重要合成策略.传统C=X(X=O,N)双键的极性翻转往往需要苛刻的反应条件和对水或空气敏感的强还原剂辅助,导致其适用范围受限.近年来,可见光催化反应以其独特高效的单电子转移特性,在室温条件下实现了这一类贫电子官能团向亲核性中间体的高效转化.该策略已经拓展C=X(X=O,N)双键自身或与烷基链的偶联,从而得到烷基取代的醇和胺类化合物.本文利用可见光催化反应使C=X(X=O,N)双键极性翻转与芳香化合物的直接偶联,高效温和地合成芳基取代的醇和胺.反应无需强还原剂,底物适用范围广.该方法是对可见光催化C=X(X=O,N)双键极性翻转的重要补充,具有潜在的应用价值.本文以苯甲醛和1,4-二氰基苯为底物,fac-Ir(ppy)_3为光敏剂,二异丙基乙胺为终端还原剂,DMSO为溶剂,蓝光照射12 h能够以82%的收率实现模板反应.其它光敏剂如[Ru(bpy)3]Cl_2则不能催化该反应.溶剂效应指出,丙酮、乙腈可以得到低于40%的收率,甲醇、二氯甲烷、DMF等溶剂不适用该反应体系.控制实验证实,光敏剂、二异丙基乙胺和光照三个反应组分缺一不可.底物拓展发现,不同取代基的芳基腈类化合物包括烷基取代、砜基和酯基取代甚至杂芳环取代都能很好地适用于该体系,芳基醛、酮以及亚胺作为反应的另一组分亦能高效参与该还原偶联反应.自由基捕获实验证实反应过程中涉及自由基历程.光谱淬灭实验表明,芳香腈是唯一有效淬灭激发态fac-Ir(ppy)_3发光的物种.进一步结合底物的氧化还原电位,证实芳香腈能被激发态的光敏剂fac-Ir(ppy)_3还原,但二异丙基乙胺和芳香醛、酮不能与激发态光敏剂发生作用,催化反应经历光敏剂的氧化淬灭路径.首先,光敏剂受光激发到达激发态,与芳基腈发生单电子转移.随后,二异丙基乙胺促使失去电子的铱配合物还原再生,得到相应氮自由基阳离子.该氮自由基阳离子活化反应体系中的C=X(X=O,N)双键,使其从激发态铱物种得到电子形成苄位自由基,进而与得到电子的芳基氰偶联得到最终产物.     

基于K2S2O8-KOH体系合成羟基葫芦[6]脲的研究

基于已报道的以葫芦脲-过硫酸钾体系的羟基葫芦脲合成反应,本文研究了加入KOH对原体系的影响,在优化的反应条件下,可以较理想的产率(27%)得到目标产物。产物的结构经~1H NMR、~(13)C NMR和HR-ESI-MS进行确证。     

Optical transmission enhancement by a sub-wavelength film lens

A new sub-wavelength metallic film lens configuration is proposed, which is embedded in a thin ideal metal film, and its near field optical properties arc investigated by finite-difference time-domain (FDTD) method. It is found that the optical transmission is greatly enhanced, and the spot size can be reduced by the sub-wavelength metallic film lens in comparison with the bare aperture. This kind of lens is expected to have practical applications in the very small aperture laser (VSAL), a promising nanosource for near-field optical storage and lithography.     

Nonlinear two-photon absorption properties induced by femtosecond laser with the films of two novel anthracene derivatives

Two novel anthracene derivatives containing 4-vinylpyridine (FPEA) and 2-vinylpyridine (TPEA) poly(methyl methacrylate) films are prepared on quartz glass substrates. Their nonlinear absorption properties are investigated by using a 120-fs, 800-nm Ti:sapphire femtosecond pulsed laser operating at a 1-kHz repetition rate. The unique nonlinear absorption properties of these new compounds are observed by utilizing a Z-scan system. These two-photon absorption (TPA) properties are proven by the two-photon fluorescence excited at 800 nm. The FPEA and TPEA films have nonlinear TPA coefficients of 0.164 and 0.148 cm/GW and the TPA cross sections of 3.345 × 10-48 and 3.081 × 10-48 cm4 ·s/photon, respectively. The influence of the chemical structures on the nonlinear TPA properties of the compounds is also discussed. The highly nonlinear TPA activities of the films implied that the new anthracene derivatives are suitable materials with promising applications in super-high-density three-dimensional data storage and nano- or microstructure fabrication.     

超分辨近场结构中Bubble微结构的远场光学特性分析

以菲涅尔-基尔霍夫衍射理论为基础,建立了超分辨近场结构中Bubble微结构对高斯光束的衍射模型.分析了PtOx型超分辨近场结构(PtOx-Type-Super-RENS)中Bubble微结构的远场光学特性.结果表明,设计的Bubble微结构形成过程的简化模型可基本反映超分辨近场结构中掩膜结构在激光作用下的结构变化过程,说明了高斯衍射模型是研究薄膜微结构变化的一种有效方法.     

腐植酸对砷的吸附作用研究

腐植酸中含有大量的极性基团,对金属离子有较强的吸附性能。运用氢化物-原子荧光光谱法,以泥炭腐植酸为原料,研究了腐植酸对砷(V)离子的吸附作用和腐植酸吸附剂中砷的回收,并得出了最佳的吸附和脱附条件。实验考察了酸度、时间分别对吸附和脱附的影响。结果表明,泥炭腐植酸对砷吸附的最佳模型为Freundlich吸附方程,当溶液成中性时腐植酸对砷的吸附量较大且趋于平稳。砷的浓度为1μg/mL,溶液的pH值为7,吸附时间控制在55min时,吸附效果最佳,最大吸附率为85.49%。脱附的最佳条件为:pH值14,脱附时间20min。     

重温Pb(Zrx Ti1-x)O3铁电薄膜极化疲劳问题

具有ABO3型钙钛矿结构的Pb(ZrxTi1-xO3(PZT)展示出良好的铁电极化性能,是使用最广的铁电材料.然而,在将它应用于铁电存储时,PZT薄膜遭遇到极化疲劳问题而被SrBi2Ta2O9(SBT)等铁电体所替代,这一问题至今未能得到妥善解决.文章首先通过变温极化疲劳实验充分理解PZT极化疲劳的基本过程,然后有针对性地进行材料设计,获得基本无极化疲劳的PZT铁电薄膜.     

纳秒单脉冲激光诱导AgInSbTe薄膜的相变特性

利用磁控溅射法在K9玻璃基底上制备了Ag8In14Sb55Te23(AIST)纳米薄膜,并利用激光抽运-探测技术测量了薄膜的时间分辨反射率变化特性。研究结果表明,在合适能量密度的单脉冲纳秒激光脉冲作用下,AIST薄膜可以快速从沉积非晶态转化为晶态结构,晶化过程包含中间熔化态。在较低能量密度范围内,反射率变化量和晶化时间都随能量密度变化呈线性增加趋势。     

Molecular Dynamics Simulation of Ion Implantation into HfO2 and HfO2／Si Multi-Layer Structure

We simulate the B, As and P implantations into HfO2 from 3keY to 40keY by a simulator LEACS developed based on molecular dynamics method and by the traditional Monte Carlo simulator TSUPREM4 respectively. The LEACS results accurately fit with the SIMS (secondary ion mass spectroscopy) data, while the TSUPREM4 results deviate from the SIMS data obviously except B implantation. Based on the verification of the simulator, influence of the oxide thickness on the retained range profiles in the Si layer has been quantitatively investigated in the case of HfO2/Si and SiO2/Si structures. The range profiles in the Si layer through HfO2 shift to the surface obviously for about 0.68 times of the oxide layer thickness on the average in comparison to those through SiO2. It can be predicted that this effect will have a significant impact on MOSFET (metallic oxide semiconductor field effect transistor) device performance in the integrated circuit process of the next decade if HfO2 is used to replace SiO2 as the gate dielectric.