Au_n(n=2-7)在金红石型TiO_2(110)面吸附的理论研究

采用密度泛函理论,在分子水平上研究了负载金团簇对金红石型二氧化钛光催化性能的影响及机理。优化得到了6种金团簇(n=2-7)稳定结构,并分别吸附于金红石型二氧化钛(110)面形成稳定吸附体系。研究表明,Au_n团簇与TiO_2(110)面上的氧原子形成共价键,属于化学吸附,Au-O键长是影响体系稳定性的主要因素,奇数Au_n团簇吸附稳定性优于偶数的,出现奇偶振荡现象; Au_n团簇使TiO_2能带发生裂分,在禁带中增加多个能级,随着Au_n团簇的增大,TiO_2禁带宽度明显变窄,吸收光进入可见光区,增强了二氧化钛的光催化性能。     

远红外纳米陶瓷对叉鞭金藻生长的影响

单细胞藻类是鱼、虾、贝类等苗种生产的重要基础性活饵料.探索单细胞藻的培育新技术对于解决饵料藻类生产中的诸多问题具有重要的现实意义.远红外纳米陶瓷具有改变水分子团簇结构诱发生物效应的功能.本试验在叉鞭金藻(Dicrateria sp.)培养瓶中放入远红外纳米陶瓷材料一枚,其他培养条件与对照组相同,在培养结束时,置入纳米陶瓷的试验组的最高藻密度为345.3×104～397.8×104cells/cm3,而所有对照组在平台期能达到的最高藻密度为293.8×104～323.0×104cells/cm3,平均增长约20%,试验组达到最大密度的时间比对照组达到最高密度的时间提前了2～4d,试验组与对照组存在显著性差异,表明远红外纳米陶瓷可促进叉鞭金藻的生长,具有生产应用的前景.     

旋转层化二维海洋中扰动的连续谱临界层分析

讨论了旋转层化二维海洋垂直切变基本流中海洋内部波动扰动连续谱临界层出现的情况和可分性问题.当存在垂直切变基本流时,横波型扰动表现为3类波动:一对重力惯性波和一支涡旋波,这3类波动均存在连续谱和临界层;当扰动波长大于该临界波长的1/2而小于临界波长时,则涡旋波的连续谱与重力惯性波的连续谱两波可发生重叠,但临界层不相重叠.在扰动尺度和地转参数小而基本流切变大的条件下, 扰动波长小于临界波长的1/2时,这3类波动的连续谱会发生重叠,在重叠区会出现涡旋-重力惯性混合波,临界层可能发生重叠.     

蒸汽冷凝过程的分子团聚模型及其对不凝性气体影响传热性能的解释

根据相变过程的微观物理机理和热力学特性,提出了冷凝传热过程中,近壁面蒸汽分子经由团聚阶段进而冷凝成宏观液滴的物理模型.并将团聚体分布与滴状冷凝传热性能相联系,从而研究不凝性气体对滴状冷凝传热过程的影响.在改进的Dillmann和Meier(DM)模型基础上,将分子团聚过程中的临界过饱和度与冷凝过程中的过冷度相联系,以及将团聚体的能量特性与液固界面物理化学特性相联系,将团聚模型与考虑固液界面效应的滴状冷凝传热模型相联系,建立了近壁面条件影响的分子团聚模型.利用模型计算了近壁面蒸汽中团簇体尺寸和分布,以及不凝     

Fe-Al金属间化合物抗腐蚀性能的密度泛函研究

应用BPW91/Lanl2dz/6-31g(d)方法深入研究Al原子掺杂Fen(n≤8)团簇的基态结构和稳定性,获得较为准确的几何信息.为了消除基组误差,在Lanl2dz/6-31g(d)混合基组优化结构的基础上,应用全电子基组(6-311 g(2d,2p)进行单点计算,获得的能量与该基组全优化结果一致.通过计算发现1个Al原子很难掺杂到铁团簇结构的中间,倾向于分布在铁簇的表面,并且它的掺杂也难以改变铁簇的主体结构.对Fen-1Al团簇进行稳定性分析,二级能量差分、HOMO-LUMO能隙以及垂直电离势都一致表明Fe3Al具有特殊的稳定性.而Fe3Al金属间化合物具有优异的抗氧化、抗硫化以及耐海水等腐蚀性能,很好地支持了作者的理论结果.因此,应用密度泛函方法获得的量化参数能从原子、分子角度反映Fe-Al合金的耐腐蚀性能.     

退火对B掺杂纳米金刚石薄膜微结构和电化学性能的影响

采用热丝化学气相沉积法制备B掺杂纳米金刚石薄膜,并对薄膜进行真空退火处理,系统研究了不同退火温度对B掺杂纳米金刚石薄膜的微结构和电化学性能的影响.结果表明,当退火温度升高到800 ℃后,薄膜的Raman谱图中由未退火时在1157,1346,1470,1555 cm^-1处的4个峰转变为只有D峰和G峰,说明晶界上的氢大量解吸附量减少;并且D峰和G峰的积分强度比I_D/I_G值变为最小,即sp²相团簇     

密度泛函理论对ZrnPd团簇结构和性质的研究

用B3LYP/LANL2DZ方法对Zr_nPd(n =1—13)团簇的平衡几何结构、能量、频率、电子性质和磁性进行了计算.研究表明,Pd原子位于表面的异构体更为稳定,其中Zr₇Pd,Zr₁₂Pd团簇稳定性高,是幻数团簇;此外,相对于Zr_nCo与Zr_nFe团簇,Zr_nPd团簇参与化学反应的能力较弱,化学稳定性更     

不等直径串列双圆柱体绕流的数值模拟

利用Fluent软件模拟雷诺数为200时不同间距比G/D和直径比d/D情况下的圆柱绕流现象。根据模拟结果分析G/D和d/D对圆柱体的涡脱落形态,大、小柱体的升力,阻力系数和St数的影响,结果表明涡脱落形态随着G/D和d/D的变化呈现不同的形式,在G/D小于临界间距比时呈现单一涡脱落形态,在G/D大于临界间距比时,呈现双旋涡脱落形态;临界间距比随着d/D增大而增大。在临界间距比附近大、小柱体的升力和阻力系数值及St数变化较大,大、小柱体的St数具有相同的变化规律,St随着d/D的增大而减小。     

大海马游泳行为及游泳能力测定与分析

利用自制的鱼类游泳能力测定装置,观察了大海马垂直和水平方向的最大临界游速,描述了大海马的游泳行为,并评估其游泳能力。结果表明:水温25.5℃±1.0℃条件下,体长6 cm个体水平方向的临界游速达到峰值为4.23 cm/s±0.23 cm/s;随体长的增加和减少,临界游速都有所下降,体长至约10 cm时临界游速为2.86 cm/s±0.02 cm/s。该物种在水平游泳时,游泳速度与尾部的倾斜角度有关,倾角越大,速度越大,当倾角达到55°时,速度达到最大值,而大于该角度,身体就失去平衡不能进行逆水流游动。大海马体长在6 cm时达到垂直方向的临界游速峰值,为0.372 cm/s±0.014 cm/s,此时的绝对临界速度为0.085 BL/s±0.010 BL/s。至体长增长到13 cm时,基本趋于稳定,与水平方向游速变化趋势相似。     

载Fe3+纳米TiO2薄膜去除球形棕囊藻赤潮生物的研究

球形棕囊藻Phaeocystis globosa 是近年来在我国沿海频发的有毒有害赤潮藻.为了寻找一种简单、有效和安伞的去除赤潮藻的方法,探讨了纳米TiO2 薄膜以及载Fe3+纳米TiO2薄膜在可见光条件下对球形棕囊藻的除藻效果.结果表明,载Fe3+纳米TiO2除藻效果好于未载Fe3+的纳米TiO2,藻液中投加载Fe3+纳米TiO2薄膜的量为20mg·L-1时,可见光照射48h后,藻液中细胞密度由4.08×104cell·mL-1降低到0.01×104cell·mL-1,叶绿素a浓度由0.43mg·L-1降低到0.001mg·L-1,除藻率达到99.7%,除藻速率符合准一级反应动力学方程.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

《Acta Oceanologica Sinica》Vol. 33(2014) contents

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INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,