Steady Current Induced Seabed Scour around a Vibrating Pipeline

Most of the existing researches either focus on vortex-induced vibrations (VIVs) of a pipeline near a rigid boundary, or on seabed scour around a fixed pipeline. In this study, the coupling effects between pipeline vibration and sand scour are investigated experimentally. Experimental results indicate that there often exist two phases in the process of sand scouring around the pipeline with an initial embedment, i.e. Phase I: scour beneath pipe without VIV, and Phase II: scour with VIV of pipe. During Phase II, the amplitude of pipe vibration gets larger and its frequency gets smaller while the sand beneath the pipe is being scoured, and finally the pipe vibration and sand scour get into an equilibrium state. This indicates that sand scouring has an influence upon not only the amplitude of pipe vibration but also its frequency. Moreover, the equilibrium scour depth decreases with increasing initial gap-to-diameter ratio for both the fixed pipes and vibrating pipes. For a given value of initial gapto- diameter ratio (e0/D), the vibrating pipe may induce a deeper scour hole than the fixed pipe in the examined range of initial gap-to-diameter ratios (−0.25 < e0/D < 0.75).

Physical Modeling And Parametric Study On Two-Degree-Of-Freedom Viv Of A Cylinder Near Rigid Wall

Unlike most previous studies on the transverse vortex-induced vibration(VIV) of a cylinder mainly under the wallfree condition (Williamson & Govardhan,2004),this paper experimentally investigates the vortex-induced vibration of a cylinder with two degrees of freedom near a rigid wall exposed to steady flow.The amplitude and frequency responses of the cylinder are discussed.The lee wake flow patterns of the cylinder undergoing VIV were visualized by employing the hydrogen bubble technique.The effects of the gap-to-diameter ratio (e0/D) and the mass ratio on the vibration amplitude and frequency are analyzed.Comparisons of VIV response of the cylinder are made between one degree (only transverse) and two degrees of freedom (streamwise and transverse) and those between the present study and previous ones.The experimental observation indicates that there are two types of streamwise vibration,i.e.the first streamwise vibration (FSV) with small amplitude and the second streamwise vibration (SSV) which coexists with transverse vibration.The vortex shedding pattem for the FSV is approximately symmetric and that for the SSV is alternate.The first streamwise vibration tends to disappear with the decrease of e0/D.For the case of large gap-to-diameter ratios (e.g.e0/D = 0.54～1.58),the maximum amplitudes of the second streamwise vibration and transverse one increase with the increasing gapto-diameter ratio.But for the case of small gap-to-diameter ratios (e.g.e0/D = 0.16,0.23),the vibration amplitude of the cylinder increases slowly at the initial stage (i.e.at small reduced velocity V,),and across the maximum amplitude it decreases quickly at the last stage (i.e.at large Vr).Within the range ofthe examined small mass ratio (m＜4),both streamwise and transverse vibration amplitude of the cylinder decrease with the increase of mass ratio for the fixed value of V,.The vibration range (in terms of Vr ) tends to widen with the decrease of the mass ratio.In the second streamwise vibration region,the vibration frequency of the cylinder with a small mass ratio (e.g.mx = 1.44) undergoes a jump at a certain Vr,.The maximum amplitudes of the transverse vibration for two-degree-of-freedom case is larger than that for one-degree-of-freedom case,but the transverse vibration frequency of the cylinder with two degrees of freedom is lower than that with one degree of freedom (transverse).

利用耳石日轮技术研究长江中游草鱼幼鱼的孵化期及生长

根据耳石日轮对2004年采自洞庭湖和新滩口江段的草鱼幼鱼进行日龄(D)鉴定,孵化时间推算以及生长的研究。草鱼幼鱼所有样品体长(BL,mm)生长方程为BL=-53.4195+3.1650D,体重(W,g)生长方程为W=0.9816 e0.0633D,体长体重相关方程为W=0.00001BL3.1003。孵化时间最早为5月14日,最晚为7月11日,主要集中在5月下旬和6月份。研究发现三峡大坝在139m水位运行后长江中游仍有草鱼产卵,最早繁殖时间稍晚于历史记录。

四种底栖螺类饥饿代谢的研究

研究了四种常见优势底栖螺类的饥饿代谢(R,mgO2/ind.d)与温度(T,℃)、体重(Wd,mg dry-wt或Ww,mg wet-wt)的关系,并计算出三者间的复合关系,分别是:铜锈环棱螺,R=0.044Wd0.537e0.061T;长角涵螺,R=0.0004Ww0.9405·e0.0735T;纹沼螺,R=0.004Wd1.072e0.091T;短沟蜷,R=0.023Wd0.777e0.042T。

模拟生物膜的电化学研究

本文简要介绍了生物膜的组成、结构和一些基本性质，详细描述了各种生物膜模型（支撑磷脂双层膜、非支撑磷脂双层膜、泡囊等等）的制备方法。概要地总结了模拟生物膜的各个领域的研究情况，着重评述了模拟生物膜在电化学、生物传感器、膜片钳、图案化领域的研究进展。采用电化学、各种谱学以及扫描探针显微镜等方法对支撑双层磷脂膜、磷脂浇铸膜等不同的模拟生物膜体系进行了研究。主要结果如下：1．将一种支撑磷脂膜一杂化双层膜（Hbrid bilayerer membrane，HBM）首次用于钙离子与磷脂作用的研究，以Fe（CN）63-为探针，发现钙离子可诱导HBM产生离子通道，且通道的打开与关闭能反复运转，并用STM观察这一现象。2.Ru（bPy）32+的电化学发光法和电催化法被首先用于研究支持脂质双层膜（sBLM）的离子通道行为。高氯酸根可以诱导DODAB（dimethyldioctadecylammonium）产生离子通道行为。离子通道的产生存在着一个闺值，当高氯酸根阴离子的浓度超过0.1μM时离子通道打开，当浓度低于0.1μM时离子通道关闭。当高氯酸根离子浓度高于0.1μM时，被打开的离子通道的数量随着高氯酸根阴离子浓度的增加而增加，在1200μM时达到平衡。离子通道的打开和关闭行为是可逆的。在此基础上，研制了一种用于检测高氯酸根离子的传感器。3，用循环伏安法和交流阻抗法研究了稀土离子与支撑磷脂双层膜的相互作用．稀土离子可以影响支撑磷脂双层膜的结构，使之产生一些小孔，通过这些小孔Fe（CN）63/4可以到达电极表面，显示其电化学行为。Fe（CN）63／4-的氧化还原电流随着稀土离子的浓度的增加而变大，对于E矿＋当浓度达到1．2卿时，电流不再增加。发现三种稀土离子与膜作用的能力如下：Eu3+＞Th3＋＞La3＋。4．铁氰酸根离子通常被用来作离子通道传感器的标记物。在本项工作中，我们首次发现铁氰酸根离子本身也可以作为一种刺激物来控制玻碳电极上DDAB（一种合成磷脂）制备出的支撑双层磷脂膜的通透性。我们利用循环伏安、交流阻抗的方法来研究这种现象。支撑双层磷脂膜与铁氰化物的反应与时间有关。进一步地，我们研制了一种铁氰酸根离子传感器。这种离子通道响应灵敏度较高，它可以检测的铁氰化物的最小浓度为5μM。5．稳定的磷脂浇铸膜是通过把含磷脂的氯仿溶液浇铸到玻碳电极上制备的。我们把一种新的媒介质一去甲肾上腺素嵌入到这种磷脂浇铸膜中。磷脂浇铸膜可以被视为一种生物膜模型。用这个体系对抗坏血酸进行电催化氧化，与在裸玻碳电极上相比，阳极过电位降低了约250 mV。浇铸膜内去甲肾上腺素的电化学行为是受扩散控制的，其扩散系数是1.87×10-5cm2／s。在浓度为0.5-10 mmol／L的范围内，催化电流随抗坏血酸的浓度增大而呈线性增加。在同时含有抗坏血酸和尿酸的溶液中，我们用循环伏安法可以同时侧得两个峰，这两个峰之间的峰位差大约为147mV。6．卵磷脂泡囊和血红蛋白在热解石墨电极上制备的薄膜内，血红蛋白可以实现其直接电化学。血红蛋白在薄膜内表现出薄层电化学行为。其式电位E0在pH 3.5-7.0内随pH值直线变化，斜率为-46.4 mV/pH。磷脂膜内的血红蛋白对H2O2显示了很好的催化还原行为。基于此，研制了无媒介体的H2O2传感器。7．我们合成了一种人工磷脂（二甲基二（十二烷基）澳化钱，DDAB）保护的金纳米粒子。在这些金纳米粒子的促进下，血红蛋白可以表现出直接电子转移（DET）反应，其式电位位于-169mVvs Ag/AgCl参比电极。光谱数据表明电极上的血红蛋白没有变性。这种磷脂保护的金纳米粒子很稳定（至少8个月），它们的平均直径是6.42nm。这是首次应用单层膜保护的纳米粒子去实现蛋白质的直接电化学反应。8．我们在一种新的基底一碳电极上构建了杂化双层膜（HBM）。这是对其它基底上构建的HBM的一种扩展。首先，通过电化学扫描将烷基胺修饰在碳电极表面，使之在电极上形成单层膜。由于烷基链部分向外，因此所构筑的界面是疏水的。然后在碳电极的疏水表面铺展一层磷脂单层膜。所生成的HBM通过电化学和ATR-FTIR技术来表征。根据ATR-FTIR的结果，脂质的有序常数（S）为0.73。这种杂化膜具有磷脂／烷基硫醇HBM的优点。这种HBM在生物传感面具有潜在的应用。

烙铁头(TRI MERESURUS MUCROSQUAMATUS)蛇毒中精氨酸酯酶的研究

采用DEAE－sephadex A-50、Sephadex G-100、CM-sepharose cl-6B三步柱层析，从烙铁头(T. mucrosquamatus)蛇毒中纯化得到的精氨酸酯酶在聚丙烯酰胺凝胶电泳(pH 8.3)和SDS－聚丙烯酰胺凝胼电泳中均呈现单一的蛋白带。其分子量为29000，等电点pI为5.2；由225个氨基酸残基组成，其中Gly,Asp和Glu的含量较高。它是一个糖蛋白，含有0.5%的中性已糖和0.75%的唾液酸，对热及酸碱变化较稳定。在280nm波长处有典型的蛋白质吸收峰，此时的消光数E0.1%/1cm为1.332。该酶具有较强的精氨酸酯酶活性和纤维蛋白原溶解活性，无出血活性、酪蛋白水解活性以及粗毒中含有的其它酶活性。从烙铁头(T. mucrosquamatus)蛇毒中纯化的具纤维蛋白原溶解活性的精氨酸酯酶（MFAE）是一丝氨酸蛋白酶，其活性可被PMSF抑制而不受EDTA的影响。MFAE酶促反应的最适pH为8.4，最适温度55 ℃; pH7.6、37 ℃时水解BAEER的米氏常数K_m为20 * 10~(-3)M。该酶能降解纯化人纤维蛋白原的Bβ链以及纯化牛纤维蛋白原的Aα和Bβ链，并有一定的纤维蛋白溶解活性。它能明显延长兔血浆的凝血酶时间和复钙时间。纯化的MFAE无出血活性、凝血酶样活性及血小板聚集活性，对ADP、AA、TMVA、Melittin等诱导的血小板聚集也无抑制或解聚作用。本文还测定了它对凝血酶及胞浆毒特异性合成三肽底物的水解活性。

Resonant Raman Scattering and Photoluminescence Emissions from Above Bandgap Levels in Dilute GaAsN Alloy

The transitions of E0 ,E0 ＋A0, and E＋ in dilute GaAs（1-x） Nx alloys with x = 0.10% ,0.22% ,0.36% ,and 0.62% are observed by micro-photoluminescence. Resonant Raman scattering results further confirm that they are from the intrinsic emissions in the studied dilute GaAsN alloys rather than some localized exciton emissions in the GaAsN alloys. The results show that the nitrogen-induced E E＋ and E0 ＋ A0 transitions in GaAsN alloys intersect at a nitrogen content of about 0.16%. It is demonstrated that a small amount of isoelectronic doping combined with micro-photoluminescence allows direct observation of above band gap transitions that are not usually accessible in photoluminescence.

梯度材料的黏附接触封闭解

本文给出了半径为R的刚性球体与梯度材料弹性半空间黏附接触的封闭解。梯度材料的杨氏模量随深度呈幂次变化E=E0(z/c0)k,考虑接触体表面力的作用,最终得到了外加载荷与接触半径的显式关系,及拉脱时的临界外力及临界半径的解析表达式。当k为0时,结果则为著名的JKR理论解;当k=1时,则得到Gibson材料的黏附接触封闭解。本文的解析结果为进一步分析梯度材料的黏附特性及工程实际应用提供了有效的理论工具。

E_0值对潜水蒸发计算精度影响分析

目前常用潜水蒸发经验公式中,都包含了埋深为零时的潜水蒸发强度,并认为可用水面蒸发强度代替。但对不同土质,由于土壤含水孔隙大小及与大气直接交换的空间不同,必然造成不同土壤质地埋深为零时的蒸发量差异。选用阿维里扬诺夫公式、清华公式和叶氏公式,利用新疆渭干河灌区地下水均衡试验场实测潜水蒸发数据、就E0分别为水面蒸发强度和埋深为零时潜水蒸发强度两种情况进行计算与对比分析。结果表明:除细砂和砾石外,若用水面蒸发强度代替埋深为零时的潜水蒸发强度,计算结果会产生一定误差,应选用埋深为零时的潜水蒸发强度进行计算。提出了清华公式中参数η新的求解方法,建立了η与地下水埋深的指数函数关系。研究结果对潜水蒸发经验公式求解不同土质潜水蒸发量时E0的选用及清华公式中参数η的计算提供参考。

含铜氧化酶在活性炭上的固定及直接电化学

以吸附的方法将两种具有代表性的含铜氧化酶酪氨酸酶(Tyr)和漆酶(Lac)固定在活性炭粉表面, 结果表明, 活性炭能促进Tyr和Lac的直接电子转移反应, 循环伏安曲线上表现出一对准可逆的氧化还原峰; 式量电位E0' 几乎不随扫速而变化. 进一步的实验结果显示, 固定在活性炭上的Tyr和Lac能保持对O2还原的电催化作用. 本文固定酶的方法具有简单、易于操作和酶活性保持良好等优点, 可用于获得其他生物氧化还原蛋白质和酶的直接电子转移以及制备生物燃料电池电极催化剂.

铁氰化钐修饰电极的制备、表征及电催化

用电化学循环扫描的方法将铁氰化钐沉积在玻碳电极表面,形成铁氰化钐修饰电极(SmHCF/GC),扫描电镜研究表明,SmHCF颗粒(113±13)μm附着在电极表面;红外光谱结果表明,SmCHF中CN的弯曲振动吸收峰出现在20615cm-1处。SmHCF/GC在循环伏安曲线上出现一对很好的氧化还原峰,在20mV/s时,氧化还原峰电位分别为Epa=207mV,Epc=171mV;式量电位E0′=189mV;随着支持电解质浓度的增加,氧化还原峰电位正移,式量电位E0′与支持电解质浓度(logc)之间有线性关系,斜率为504mV。SmHCF/GC电极对神经递质多巴胺(DA)的氧化具有电催化作用,催化电流随DA浓度的增加而增加,在10～150mmol/L范围内有线性关系。

APPLICATIONS OF RAPID SCAN SPECTROELECTROCHEMISTRY - DETERMINATION OF HETEROGENEOUS ELECTRON-TRANSFER RATE-CONSTANT OF BILIVERDIN OXIDATION

The rapid scan spectrometer was used to determine the heterogeneous electron transfer rate parameters for the oxidation of Biliverdin in DMF by single potential step thin layer spectroelectrochemical techniques and yielded an average formal heterogeneous electron transfer rate constant K(s, h)0' = 2.45 (+/-0.12) x 10(-4) cm s-1, electrochemical transfer coefficient alpha = 0.694+/-0.008. The oxidation process of Biliverdin was also studied and the formal potential E0 = 0.637 V (vs. Ag/AgCl) was obtained.

SPECTROELECTROCHEMICAL STUDY OF BILIRUBIN IN DIMETHYL FORMAMIDE

The electrochemical reduction of bilirubin (BR) in dimethyl formamide (DMF) is discussed in detail. The kinetic study of the electroreduction process of BR results in values of 7.94 x 10(-6) cm2/s for the diffusion coefficient and about 10(-3) cm/s for the standard heterogeneous electrode reaction rate constant. Thin-layer spectroelectrochemical investigations of BR exhibit a blue shift and a red shift at E(pc) = -0.6 V and E(pc) = -0.85 V respectively. They also give values of E0' = -1.55 V and n = 1 for the reduction process, and E0' = -1.35 V and n = 1 for the oxidation process. It was found experimentally that as the potential changes from negative to positive, the sequential color changes are similar to those of some of the color components in visible light. A mechanism for BR electroreduction in DMF has been proposed.