水下声辐射激励水表面声波的特征参数测量

采用激光干涉方法对水下声辐射激励水表面声波的特征参数频率和振幅进行了测量研究。从理论上对水表面声波激光相干测量信号的频谱构成进行了分析,在此基础上提出了水表面声波两个重要声学参数频率和振幅的解算方法,并通过数值仿真进行了验证。搭建了一套简单的激光干涉测量实验系统,对不同频率和声压激励的水表面声波进行了测量实验,验证了水表面声波频率和振幅解调方法的准确性。对水表面声波横向传播的振幅衰减现象进行了初步的实验研究,结果表明水表面声波的频率越高,振幅的横向衰减越快。研究表明激光相干检测方法能够准确地实现水表面声波振幅和频率的测量。     

氦同位素与氢分子碰撞的振转激发分波截面研究

用密耦近似方法和Tang-Toennies势模型计算了E=0·7eV时,氦原子的四种同位素3He,4He,9He,10He与氢分子H2碰撞体系的振转激发分波截面.通过分析各碰撞体系分波截面的差异,探讨了He(3He,4He,9He,10He)-H2碰撞体系的弹性碰撞、纯转动激发和振转激发情况下,其分波截面随量子数和体系约化质量的变化规律.     

氢及氘的宽区物态方程研究进展

氢是自然界最丰富的元素,是天体物理和惯性约束聚变（ICF）研究的重要对象。简要综述了国内外氢及氘宽区物态方程研究进展,特别评述了OMEGA激光装置上的最新冲击压缩实验和理论模型的对比分析情况。在以往数据分析评估基础上,利用改进的化学自由能模型、第一原理数值模拟结果及多参数物态方程模型,构建了氢的宽区物态方程,适用温度、密度范围分别为20～10⁸ K,10⁻⁷～2000 g/cm³。与已有多类实验如冲击压缩实验、静高压等温线实验、声速等实验结果对比表明,新构建的氢宽区物态方程具有较高的置信度,为天体物理、惯性约束聚变、国际热核实验堆等工程物理设计提供高精度的支撑数据。氢宽区物态方程的构建及验证方法亦可适用于其同位素氘,该方法构建的氘宽区物态方程与2019年最新发表的主雨贡纽、二次冲击雨贡纽数据的吻合程度明显优于当前国外模型。指出了未来研究需要关注的状态区域。     

Gas-phase photoreactions of anthracene, 2-aminoanthracene,and pyrene with oxygen and water vapors

Excited singlet (S ₁) and triplet (T ₁) state quenching by O₂ and by (O₂ + H₂O) gas-vapor mixtures was studied in the gas phase for polycyclic aromatic hydrocarbons (PAHs, anthracene, 2-aminoanthracene, pyrene). Addition of water vapor is shown not to influence quenching of both fluorescence and delayed fluorescence of PAHs by oxygen. The role of complexes stabilized by charge transfer and hydrogen bonds in quenching the excited states of PAHs by atmospheric gases was analyzed. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 342–348, May–June, 2009.     

AgF desalination procedure for the routine determination of oxygen and hydrogen isotopic composition of saline waters and brines

The routine methods for stable oxygen and hydrogen isotope analysis of water involve water–CO₂ gas equilibration and water reduction on hot metal (e.g. Zn, Cr, U) and subsequent mass spectrometric analysis of the evolved gases of CO₂ and H₂ for ¹⁸O/¹⁶O and ²H/¹H ratios, respectively. Precise determination of the isotopic composition of water in brines with application of these standard methods is still problematic and technically often impossible due to detrimental influence of dissolved salts. The new method of brine desalination presented in this study overcomes the problem of the isotope salt effects encountered during the application of the routine techniques for the determination of the isotopic composition of high saline waters. The procedure combines two technical steps: (i) the chemical precipitation of Mg and Ca ions as insoluble non-hydroscopic fluorides, and (ii) the vacuum distillation of water from solution–precipitate mixture. The application of simple vacuum distillation allows full extraction of water and dehydration of remaining salts in a temperature range from 300 to 350?°C without hydrogen and oxygen isotope fractionation. The precision and accuracy of δ¹⁸O and δ²H determination of saline waters and brines with prior application of AgF desalination procedure is comparable with that usually obtained for fresh waters.     

The influence of the benthic frontal zone on acoustic wave propagation in the ocean and evaluation of the possibilities of its ray tomography

The specificity of ray trajectories in the presence of a benthic front, which is the boundary between the Antarctic deep and bottom waters, has been considered. Deep-water “noncanonical” caustic surfaces confined to the front have been found. The ability to reconstruct a sound velocity profile in the benthic frontal zone has been evaluated using methods of ray tomography in the ocean. A possible reconstruction of the profile using a horizontal displacement of the receiving antenna or transmitter at relatively small depths has been shown. Original Russian Text ? V.S. Ivanov, P.N. Kravchun, 2009, published in Vestnik Moskovskogo Universiteta. Fizika, 2009, No. 2, pp. 92–97.     

Snow gauge undercatch and its effect on the hydrogen and oxygen stable isotopic composition of precipitation

ABSTRACT

We investigated the influence of post-collection changes and snow gauge undercatch on the stable isotopic compositions of winter precipitation. Post-collection changes by evaporation or sublimation can be severe, and may be minimized, but not eliminated, by emptying collection gauges immediately after snowfall. Snow gauge undercatch caused two main effects: a small direct effect caused by preferential separation of snow particles during snowfall, and a much larger effect on the measured stable isotopic compositions of average annual precipitation as a result of under representation of winter precipitation. Despite these effects, however, we found little change to calculated local meteoric water lines (LMWL) for Saskatoon, SK, Canada. A comprehensive 27-year LMWL for Saskatoon which incorporates these effects can be described by δ²H?=?7.69?±?0.096?×?δ¹⁸O?–?2.22?±?1.72 (r²?=?0.97, n?=?208).     

不同荷载水平及速率下超软土水相核磁共振试验研究

大规模建设中面临越来越多的淤泥等超软土地基处理,其目的是尽可能排出超软土体中的水而使土体固结,以改善其物理力学性能.静动力排水固结法试图利用高能量冲击而将超软土中部分结合水转换为自由水,进而实现更多水的排出而有效固结.然而,目前还不十分清楚能造成这种水相变化的冲击荷载究竟要达到何种水平及速率.为此,在模拟条件的、淤泥土的不同类型荷载水平及速率试验基础上,进行核磁共振水相测试,探索了典型荷载水平及速率下这种超软土中结合水可转化为自由水的条件及规律,主要为:1)对应于通常工程荷载的较低能量真三轴试验荷载速率与水平(1.6 MPa/s与100 kPa及以下),淤泥类超软土中非自由水不能转化为自由水.2)对应于静动力排水固结法条件的高速冲击荷载下(每击荷载水平3787 kPa,速率631.2 MPa/s),非自由水可转化为自由水;且冲击总能量越大(遍数及击数越多),就越易析出自由水.3)约束样品的侧限刚度对非自由水转化为自由水的影响可忽略.     

同时基于氢键和卤键的尿素含碘衍生物对卤素阴离子的识别机理

采用密度泛函B3LYP(Becke, three-parameter, Lee-Yang-Parr)量子化学理论方法探讨了同时基于氢键和卤键者两种弱相互作用的尿素无氟含碘衍生物对卤素阴离子（F-,Cl-,Br-和I-）的识别机理, 结果发现尿素衍生物受体分子A以其结构中的两个N-H键和两个C-I与卤素阴离子间形成四齿弱键进行识别. 其中包括2个N-H…X-红移氢键和2个C-I…X-蓝移卤键弱相互作用. 另外, 经BSSE校正后的A…F-, A…Cl-, A…Br-和A…I-分子识别体系中相互作用能ΔECP分别为-48.90, -121.78, -311.42和-96.55 kJ/mol, 从结合强度上来看, 受体A对Br-和Cl-具有较好的识别能力, 而对F-的识别能力相对较弱. 此外, 采用自然键轨道(NBO)理论分析了C…X-（X= F-,Cl-,Br-和I-）识别体系中红移氢键和蓝移卤键的电子行为与性质.