十八胺单分子膜的研究

通过测定在纯水和CdCl2 溶液亚相上十八胺单分子膜的平衡、循环π～A等温线及其动态弹性 ,发现在亚相中加入Cd2 + 可以使膜的液态相凝聚性增强 ,固态相凝聚性减弱 .液态的单分子膜在两种亚相上有较好的可回复性 ,而在固态膜中则不然 .这可归因于在水面上十八胺分子间可形成氢键 ,而在CdCl2 水溶液亚相上的十八胺则与Cd2 + 发生配位 ,形成了多配位络合物 ,两种情况下十八胺分子在高膜压区都会发生稳定的聚集 .静、动态弹性的比较表明 ,膜障的振动不利于十八胺分子与Cd2 + 间的配位作用     

4-甲基-5-羟乙基-噻唑-十八酸酯的合成、表征及成膜性能研究

合成了一种新型两亲分子4－甲基－5－羟乙基－噻唑－十八酸酯（以下简写为HISE），利用FTIR，^1H NMR,MS等手段对其进行了表征，并研究了在不同pH值的亚相溶液中HISE单分子膜的形成，通过表面压－分子面积等温线（π－A）的测定，发现随着亚相pH值的增加，单分子膜的崩溃压升高，HISE的成膜性能逐渐增强，单分子膜从膨胀型向压缩型转变。通过对微分曲线dπ／dA-A的分析，研究了不同pH值的亚相中HISE单分子膜的不可压缩性和相变过程。结果表明，碱性介质中HISE单分子膜具有良好的稳定性和不可压缩性。     

Effects of Calcium Ions on Thermodynamic Properties of Mixed Bilirubin/Cholesterol Monolayers

通过?-A等温线研究了含钙离子浓度不同的水溶液亚相上胆红素/胆固醇混合单分子膜的性质．在此基础上,采用数学方法计算了不同亚相上单分子膜的平均单分子面积、崩溃压、表面压缩系数、超额单分子面积、混合自由能和超额自由能．结果表明,在钙离子溶液亚相上混合单分子膜的结构发生扩张,并且在界面上形成非理想混合单分子膜．与理想混合时相比,这种混合单分子膜在超额单分子面积上表现为明显的正偏差．在纯水亚相上,胆红素与胆固醇的摩尔比为3:2时混合单分子膜为热力学最稳定体系．但是在钙离子浓度逐渐增大的亚相中,这种摩尔比的混合单分子膜热力学稳定性被破坏,即混合单分子膜中的不同组分间自发混合能力下降,这是由于受到钙离子与胆红素和胆固醇之间配位作用的影响．此外,在钙离子溶液亚相中,在较低的表面压下制备出的混合膜具有更好的热力学稳定性．     

不对称冠醚酞菁LB膜制备过程中的亚相诱导作用

制备了单冠醚取代的不对称酞菁在不同亚相上的单层膜，并测定了π－Ａ曲线，将单层膜转移到氟化钙或单晶硅基片上，制备了多层膜，利用偏振紫外，光电子能谱和椭圆偏振对膜的结构进行了表征，证明了在膜中酞菁分子呈倾斜状态排列，分子平面和基片间的夹角受亚相中碱金属离子的影响，在纯不的表面，夹角最小，在１０＾－２ｍｏｌ／ＬＫＣｌ水溶液的表面，夹角最大，根据椭圆偏振法测定的膜的厚度可以推断，在膜中酞菁环上的疏水链呈伸     

聚酰亚胺LB膜的研究：Ⅰ聚酰胺酸N,N—二甲基十八胺前聚物的LB膜

聚酰胺酸Ｎ，Ｎ－二甲基十八胺是制备本身不具备两亲性的聚酰亚胺ＬＢ膜的前聚物。合成制备了均苯四酸二酐－４，４’－二胺基二苯酸Ｎ，Ｎ－二甲基十八胺，研究了它单分子膜的各异性，比较了伯胺和叔胺膜的不同，并用低角Ｘ射线衍射研究这前聚物ＬＢ膜分子的详细排列。     

花生酸与铈β-二酮络合物混合单分子膜的成膜特性

将铈 β 二酮络合物 (Ce(tmhd) 4)的氯仿溶液与花生酸 (AA)的氯仿溶液以不同摩尔比混合并铺展在纯水亚相上 ,得到其与AA的混合单分子膜 .对混合单分子膜的成膜特性 (π A等温线和体系超额自由能 )进行了探讨 ,发现混合单分子膜的超额自由能为负值 ,混合过程为热力学自发过程 ,且在配比为 1∶2时其绝对值最大 ,体系最稳定 ,并进一步讨论了混合单分子膜可能的凝聚态结构 .在配比为 1∶2时 ,研究了混合单分子膜的静态弹性和动态弹性     

花生酸与柿β—二酮络合物混合单分子膜的成膜特性

将β-二酮络合物(Ce(tmhd)4)的氯仿溶液与花生酸(AA)的氯仿溶液以不同摩尔比混合并铺展在纯水亚相上，得到其与AA的混合单分子膜．对混合单分子膜的成膜特性(π-A等温线和体系超额自由能)进行了探讨，发现混合单分子膜的超额自由能为负值，混合过程为热力学自发过程，且在配比为1：2时其绝对值最大，体系最稳定，并进一步讨论了混合单分子膜可能的凝聚态结构．在配比为1：2时，研究了混合单分子膜的静态弹性和动态弹性。     

酞菁铜衍生物在酞菁酮—氧化铁纳米粒子交替LB膜中的分子取向

通过Langmuir-Blodett技术制备了酞菁酮－氧化铁纳米粒子交替LB膜,利用偏振紫外－可见光谱对酞菁铜衍生物在不同制膜条件下所制得的交替膜中的分子取向进行了研究。结果表明,在同一氧化铁溶胶亚相中,随着表面压的增大,或在相同的表面压下,随着亚相中氧化铁浓度的减小,酞菁铜分子在其复合LB膜中倾斜程度变大。     

成膜条件对酞菁铜单分子膜的影响

研究了两种酞菁铜化合笺单分子膜的成膜条件，发现成膜性与铺展量、滑障速度、扩展溶剂，包埋等因素有关，通过经以上条件，可以提高其成膜性。     

季铵盐型双子表面活性剂在空气-水界面的单分子膜

利用Langmuir膜天平测定不对称双子表面活性剂12-2-16和对称双子表面活性剂12-2-12在空气-水界面上形成单分子膜的表面压,通过单分子膜的π-A等温线、微分等温线和静态弹性,分析其相转变和成膜特性.结果表明,与传统阳离子表面活性剂DTAB比较,12-2-16、12-2-12比DTAB单分子膜的分子极限面积大,崩溃压高,并有较高的静态弹性,因而具有较高的凝聚性和稳定性,其中12-2-16单分子膜的凝聚性和稳定性最高.     

Quantum effects on propagation of surface Langmuir oscillations in semi-bounded quantum plasmas

The quantum effects on the propagation of surface Langmuir oscillations are investigated in semi-bounded quantum plasmas. The specular reflection method is employed to obtain the dispersion relation of the surface Langmuir oscillations. The results show that the surface Langmuir oscillations can be propagated due to the quantum effects. It is also shown that the quantum effect enhances the propagation velocity. However, in high wave number domains, the group velocity of the propagation of surface Langmuir oscillations decreases with increasing the wave number. In addition, the electrostatic fast surface oscillating mode is found in the semi-bounded cold quantum plasmas.     

Thermodynamic properties of Langmuir layers created of monoimide perylenetetracarboxylic acid derivatives

Langmuir films formed of some fluorescent dyes, 3,4-bis-pentyl ester of 9,10-N-(n-pentylimide)-perylenetetracarboxylic acid, as well as their mixtures with arachidic acid, were studied. Surface pressure versus mean molecular area isotherms for Langmuir films were reordered and the alignment of molecules at the air–water interface was estimated. The isotherms show that the dye molecules do not lie flat onto the water surface but are tilted with respect to the normal to the interface. The surface pressure–area isotherms of Langmuir films formed from the dye/arachidic acid mixture provide evidence for phase separation of the components within almost the entire range of mole fractions. A repulsive interaction between molecules was observed in all two components of Langmuir films.     

矩形喷口欠膨胀超声速射流对撞的实验研究

在不同喷口间距和射流压力下开展了矩形喷口欠膨胀超声速射流对撞实验并与自由射流进行了对比. 实验表明:超声速射流对撞的辐射噪声中存在四种不同的啸音模式, 且随喷口距离和射流压力的变化在不同模式间切换. 在射流压力大于0.5 MPa且喷口间距小于50 mm时, 射流对撞面在两个喷口外形成两道正激波之间, 啸音基频维持在3 kHz左右. 随喷口间距的增大或射流压力的降低, 射流对撞面在一侧喷口外的弓形激波与另一侧喷口外的正激波之间. 对撞面也有可能出现在两个弓形激波之间, 对应的啸音基频约为9 kHz, 但容易受扰动而回到喷口一侧或是在喷口之间大幅度振荡. 当射流压力小于0.36 MPa且喷口间距大于70 mm后, 对撞面在两个喷口之间大幅度振荡, 产生基频在1 kHz左右并随射流压力的降低和喷口间距的增大而降低的啸音. 关键词： 超声速射流 啸音 射流对撞 激波     

Oscillating bubble concentration and its size distribution using acoustic emission spectra

New method has been proposed for the estimation of size and number density distribution of oscillating bubbles in a sonochemical reactor using acoustic emission spectra measurements. Bubble size distribution has been determined using Minnaert's equation [M. Minnaert, On musical air bubbles and sound of running water, Philanthr. Mag. 16 (1933) 235], i.e., size of oscillating bubble is inversely related to the frequency of its volume oscillations. Decomposition of the pressure signal measured by the hydrophone in frequency domain of FFT spectrum and then inverse FFT reconstruction of the signal at each frequency level has been carried out to get the information about each of the bubble/cavity oscillation event. The number mean radius of the bubble size is calculated to be in the range of 50-80mum and it was not found to vary much with the spatial distribution of acoustic field strength of the ultrasound processor used in the work. However, the number density of the oscillating bubbles and the nature of the distribution were found to vary in different horizontal planes away from the driving transducer surface in the ultrasonic bath. A separate set of experiments on erosion assessment studies were carried out using a thin aluminium foil, revealing a phenomena of active region of oscillating bubbles at antinodal points of the stationary waves, identical to the information provided by the acoustic emission spectra at the same location in the ultrasonic bath.     

Response of force behaviors of a spherical particle to an oscillating flow

Combined multi-direct forcing technique and the immersed boundary method is applied to investigate the response of force behaviors of a fixed spherical particle to an oscillating flow. The influences of the inlet oscillating flow at a mean Reynolds number of 300 with six different oscillating frequencies and three oscillating amplitudes are investigated. Three different zones with different behaviors are identified and the specific behaviors of the drag and the lift coefficients are analyzed. The averaged drag coefficient and the maximum lift force exerted on the particle increase with the increment of the oscillating Reynolds number or the oscillating amplitude. When the frequency of the inlet flow is equal to the natural vortex shedding frequency, the average drag coefficient reaches the maximum value. A linear relation between the gradient of the maximum lift coefficient and the frequency as well as the amplitude of the inlet oscillating flow is observed in certain regime.     

提高水平轴风力机叶型升力的实验研究

本文针对某水平轴风力机叶片不同叶高分布的两种叶型,在头部不同位置加入不同频率和动量的振荡射流进行对比实验研究,得到不同情况下叶型的表面压力分布。发现在叶片吸力面头部某些位置加入一定频率和动量段范围内的振荡射流,可以有效的提高叶型的升力系数,达到改善风力机叶型气动性能的目的,为风力机叶片的流动控制技术提供了一种有效的方案。     

Influence of physisorbed water molecules on the dynamics of domain wall in an amorphous ferromagnet

It was found that physisorbed water molecules affect the near-surface dynamics of a 180° domain wall in an amorphous FeCuNbSiB ferromagnet. In the range of water vapor pressures 400–1300 Pa, the oscillating domain walls suffer enhanced damping in the near-surface region and reduce their relaxation frequency from 10 to 4 kHz. This effect is explained by the influence of surface magnetic defects arising due to the pressure produced by the clusters of physisorbed water molecules on the walls of micropores at the magnet surface.     

振荡射流提高翼型升力的机理研究

本文数值模拟了施加振荡射流以及相应定常吸气条件下的翼型分离流动。对振荡射流改善翼型升力的机理进行了研究。结果表明,翼型表面施加的振荡射流能够控制流动分离的形态,提高分离区流体的湍流度,增强分离区内部流体,以及与主流的动量和能量交换,增强近壁区流体的动能,降低翼型吸力面压力,而对压力面无显著影响,因而翼型的升力得到提高。     

Quantum metastability in time-periodic potentials

In this paper, we investigate quantum metastability of a particle trapped in between an infinite wall and a square barrier, with either a time-periodically oscillating barrier (Model A) or bottom of the well (Model B). Based on the Floquet theory, we derive in each case an equation which determines the stability of the metastable system. We study the influence on the stability of two Floquet states when their Floquet energies (real part) encounter a direct or an avoided crossing at resonance. The effect of the amplitude of oscillation on the nature of crossing of Floquet energies is also discussed. It is found that by adiabatically changing the frequency and amplitude of the oscillation field, one can manipulate the stability of states in the well. By means of a discrete transform, the two models are shown to have exactly the same Floquet energy spectrum at the same oscillating amplitude and frequency. The equivalence of the models is also demonstrated by means of the principle of gauge invariance.     

Ion-specific induced charges at aqueous soft interfaces

Ionic specificity effects, i.e., ions of the same valence leading to different macroscopic effects, are studied by considering a Langmuir monolayer of arachidic acid over a solution containing either Fe(3+) or La(3+). We systematically vary pH levels as a way to control the interfacial surface charge and characterize the system by surface-sensitive x-ray scattering and spectroscopic techniques. We show that the critical surface pressure at the tilted (L2) to untilted (LS) transition is ionic specific and varies with pH. While the maximum density of surface bound La(3+) per head group of arachidic acid is ～0.3, the amount necessary to neutralize the surface charge, for Fe(3+) it is nearly 0.6 and it is accompanied with a significant accumulation of the coions Cl(-) as revealed by surface x-ray spectroscopy. We account for the experimental observations by a statistical mechanical model including ion specificity.