圆柱声学共鸣腔边界层扰动的二阶修正模型

圆柱声学共鸣法是测量Boltzmann常数和研究声学温度计的重要方法.热边界层和黏性边界层是影响圆柱声学共振频率的最主要因素。目前已有的声学一阶微扰理论已不能满足圆柱声学共鸣法精确测量Boltzmann常数的需求(不确定度小于1×10~(-6)).本文建立了基于声学二阶微扰理论的边界层扰动修正模型,计算结果表明,与一阶修正相比,二阶修正不影响圆柱声学腔的共振频率,但对频率半宽产生不可忽略的影响,且随着圆柱腔内的声学共振模式而变化,压力越低影响越大.对于长度80 mm、半径40 mm的圆柱腔,在273.16 K、50 kPa,二阶修正对Ar的(2,0,0)频率半宽的影响接近7×10~(-6).采用二阶修正模型,更符合真实物理规律,满足精确测量的需求.     

受限空间内油水界面动态特性及粘附行为的荧光原位观测

水污染作为润滑油污染的常见形式,对润滑油本身以及机械系统都有巨大的危害。为了模拟实际非均匀多相系统中的界面行为,本文搭建了高精度点接触实验台来研究传统的不溶相替换问题。将目前静态平行受限空间内油水界面行为的研究推广到动态点接触楔形受限空间内,探究了游离水滴穿过点接触狭缝间毛细油池过程中的界面特性。重点关注固壁润湿性以及固壁的分离运动对整个侵入过程中液滴动态行为的影响。实验发现了铺展系数是决定油水界面融合和分离特性的关键因素,揭示了固壁润湿性和球盘间的相对分离运动会影响游离水滴穿过毛细油池之后的粘附行为。表面张力和液体与壁面之间的粘附功能够解释观测的实验现象。     

Dicke-Narrowing Spectroscopy of Doubly Dressed Electromagnetically Induced Transparency and Singly Dressed Four-Wave-Mixing in a Confined Atomic System

Dicke-narrowing effect appears both in doubly dressed electromagnetically induced transparency and singly dressed four-wave-mixing lines due to the contribution of slow atoms resulting from de-excited effects of atom-wall collision and transient behaviour of atoms in a confined system. A robust recipe for high resolution spectroscopy of electromagnetically induced transparency dressed by two fields and four-wave-mixing lines comparable with the cold atoms is achievable in a thin vapour cell in experiments.     

二能级原子与相干态腔场相互作用过程中的纠缠交换

用量子信息学的观点，分析了发生在一个多个原子和腔场组成的系统中最大纠缠态在原子和多模类奇-偶相干态光场之间相互转移的物理过程，该系统中原子和腔场之间由依赖于强 度耦合的Jaynes-Cummings模型描述.结果发现：通过控制原子与腔场相互作用的时间，并 对原子的状态进行测量，原子的最大纠缠态可以转换为类奇-偶相干态光场的最大纠缠态，反之，纠缠的多模类奇-偶相干态光场也可以转换为原子的最大纠缠态. 关键词： 量子信息 腔量子电动力学 连续变量纠缠态 纠缠交换和传递     

Synthesis, structure, fullerene-binding and resolution of C3-symmetric cavitands with rigid and deep cavities

An efficient palladium-catalyzed Suzuki-Miyaura coupling method involving the reaction between CTV-Br(3) and a variety of aryl and heteroaryl boronic acids in the presence of indolyl phosphane ligands has been developed. This reaction procedure provided a series of C(3)-symmetric aryl-extended rigid cavitands for the first time. X-ray crystal structure analysis revealed that the phenyl substituted cavitand 5a has much larger rim edges and cavity height. This macrocyclic host adopts a linear head-to-tail "hand-shake" self-inclusion arrangement in the crystalline state. The fluorescence of 5a was considerably quenched upon the addition of C(60), with a binding constant of 78,700 ± 2300 dm(3) mol(-1) and a 1:1 stoichiometry according to the Job's plot. The interaction of C(60) with 5a in the excited state is stronger than that with CTV, which could be attributed to more binding sites in the extended arms of 5a. Moreover, optically active C(3)-symmetric cavitands (+)- and (-)-6 were easily obtained with high efficiency through chemical resolution.     

声波导管对圆柱型共鸣腔声场扰动的研究

声学共鸣法是目前测量流体热物性、热力学温度和玻尔兹曼常数最精确的方法之一,声波导管为共鸣腔提供声源和气体进入口,但是会破坏共鸣腔的理想表面从而导致腔体内气体介质共鸣频率的偏移(△f)和共鸣峰半宽的增加(g)。本文从一阶声学微扰出发建立了声波导管对共鸣腔声场的扰动模型,分析了导管位置、长度和半径大小对腔体中介质共振频率的影响。进一步测量了52～1763 mm之间六个不同长度的导管在T=332 K和p=50～500 kPa时,圆柱共鸣腔中轴向共鸣模式的共鸣频率和半宽的变化,测量结果与理论计算值吻合较好,证明了理论模型的正确性。     

水泵水轮机空载开度压力脉动特性预测

为了解水泵水轮机非同步导叶启动过程空载开度下的压力脉动特性,优化机组的性能提高并网成功几率,采用RNG k-ε模型对水泵水轮机非同步导叶空载点进行模拟,并对内部流场和压力脉动特性进行了分析。结果表明,转轮与活动导叶之间的压力脉动由叶片通过频率央定,尾水管涡带的周期性旋转导致尾水管进口呈现低频压力脉动,压力脉动幅值最大处位于预开启同步导叶与转轮之间。     

Platinum(II)-triarylpyridines complexes with electropositive pendants as efficient G-quadruplex binders

Herein we reported three new platinum(ii)-triarylpyridines complexes with peralkylated ammonium pendants that strongly stabilize G-quadruplex DNA.     

Synthesis and characterization of a Eu-containing polymer precursor featuring thenoyltrifluoroacetone and 5-acrylamido-1,10-phenanthroline

A polymerizable ligand, 5-acrylamido-1,10-phenanthroline (L), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR, MS, and ¹H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex shows a remarkable luminescence quantum yield at room temperature (40.1%) upon ligand excitation and a long ⁵D₀ lifetime (590 μs), which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor.