Studies on two-phase co-current air/non-Newtonian shear-thinning fluid flows in inclined smooth pipes

In this work. co-current flow characteristics of air/non-Newtonian liquid systems in inclined smooth pipes are studied experimentally and theoretically using transparent tubes of 20, 40 and 60 turn in diameter. Each tube includes two 10 m lone pipe branches connected by a U-bend that is capable of being inclined to any angle, from a completely horizontal to a fully vertical position. The flow rate of each phase is varied over a wide range. The studied flow phenomena are bubbly, plug flow, slug flow, churn flow and annular flow. These are observed and recorded by a high flow. stratified flow. -speed camera over a wide range of operating conditions. The effects of the liquid phase properties, the inclination angle and the pipe diameter on two-phase flow characteristics are systematically studied. The Heywood-Charles model for horizontal flow was modified to accommodate stratified flow in inclined pipes, taking into account the average void fraction and pressure drop of the mixture flow of a gas/non-Newtonian liquid. The pressure drop gradient model of Taitel and Barnea for a gas/Newtonian liquid slug flow was extended to include liquids possessing shear-thinning flow behaviour in inclined pipes. The comparison of the predicted values with the experimental data shows that the models presented here provide a reasonable estimate of the average void fraction and the corresponding pressure drop for the mixture flow of a gas/ non-Newtonian liquid. (C) 2007 Elsevier Ltd. All rights reserved.

Low-temperature (10 K) infrared measurement of interstitial oxygen in heavily antimony-doped silicon via wafer thinning

A new technique is reported for the rapid determination of interstitial oxygen in heavily Sb-doped silicon. This technique includes wafer thinning and low-temperature 10 K infrared measurement on highly thinned wafers. The fine structure of the interstitial oxygen absorption band around 1136 cm(-1) is obtained. Our results show that this method efficiently reduces free-carrier absorption interference, allowing a high reliability of measurement, and can be used at resistivities down to 1 x 10(-2) Omega cm for heavily Sb-doped silicon.

Numerical simulation of a bubble rising in shear-thinning fluids

The motion of a single bubble rising freely in quiescent non-Newtonian viscous fluids was investigated experimentally and computationally. The non-Newtonian effects in the flow of viscous inelastic fluids are modeled by the Carreau theological model. An improved level set approach for computing the incompressible two-phase flow with deformable free interface is used. The control volume formulation with the SIMPLEC algorithm incorporated is used to solve the governing equations on a staggered Eulerian grid. The simulation results demonstrate that the algorithm is robust for shear-thinning liquids with large density (rho(1)/rho(g) up to 10(3)) and high viscosity (eta(1)/eta(g) up to 10(4)). The comparison of the experimental measurements of terminal bubble shape and velocity with the computational results is satisfactory. It is shown that the local change in viscosity around a bubble greatly depends on the bubble shape and the zero-shear viscosity of non-Newtonian shear-thinning liquids. The shear-rate distribution and velocity fields are used to elucidate the formation of a region of large viscosity at the rear of a bubble as a result of the rather stagnant flow behind the bubble. The numerical results provide the basis for further investigations, such as the numerical simulation of viscoelastic fluids. (C) 2010 Elsevier B.V. All rights reserved.

Numerical simulation of a single fluid particle rising in non-Newtonian fluids

In this work, a level set method is developed for simulating the motion of a fluid particle rising in non-Newtonian fluids described by generalized Newtonian as well as viscoelastic model fluids. As the shear-thinning model we use a Carreau-Yasuda model, and the viscoelastic effect can be modeled with Oldroyd-B constitutive equations. The control volume formulation with the SIMPLEC algorithm incorporated is used to solve the governing equations on a staggered Eulerian grid. The level set method is implemented to compute the motion of a bubble in a Newtonian fluid as one of typical examples for validation, and the computational results are in good agreement with the reported experimental data．The level set method is also applied for simulating a Newtonian drop rising in Carreau-Yasuda and Oldroyd-B fluids．Numerical results including noticeably negative wake behind the drop and viscosity field are obtained, and compare satisfactorily with the known literature data.

古田山亚热带常绿阔叶林密度制约普遍性研究

密度制约是否为自然森林维持物种共存的普遍性机制，生态学家对此一直就有争议。目前密度制约的普遍性研究主要集中于热带森林，而针对亚热带森林的研究还比较少见。本文以浙江古田山24 公顷亚热带常绿阔叶林固定监测样地第一次调查数据为基础，主要采用点格局分析的双变量函数g(r)，研究了密度制约是否作用于样地内大部分木本植物，目的在于探讨密度制约在亚热带常绿阔叶林内物种多样性维持中的作用。 检验密度制约效应的常用方法是: 假定在种内竞争、种内个体之间的病虫害传播等条件下，种群的聚集程度是否随年龄的增加而下降。但是生境的异质性也可能导致种群聚集程度的下降。所以在密度制约的普遍性检验之前，首先分析了生境异质性是否影响树木的分布，然后分析种群分布格局，探讨除了生境异质性以外其它影响种群分布的驱动因子，同时为分析密度制约的发生做解释。结果发现生境异质性影响古田山树木的分布。用完全随机零模型不排除异质性，被检验的64个物种几乎在0-30m所有的尺度上都表现聚集。用异质性泊松分布零模型排除异质性，59个被检验物种中58个表现聚集。排不排除异质性，同种聚集都在整个样地中占主要地位，而且随着远离目标个体同种个体的密度逐渐下降，植株主要聚集在同种邻体的周围。结合下面的关联性分析，更新植株主要集中在成年个体周围，说明除了生境异质性效应促进树木聚集分布以外，以繁殖体为中心的局部扩散是大部分物种同种聚集的主要原因。 环境异质性影响树木分布，干扰密度制约的检验。然而，排除生境异质性的影响，也不能肯定密度制约是否是群落物种多样性普遍性的维持机制。用随机标签零模型案例-对照设计，小径级生长阶段的树木格局作为案例，成年树作为对照代表生境异质性的作用，通过小径级树木格局与成年树格局相比，排除生境异质性的干扰，64个被检验物种中50种(78.1%)表现了密度制约稀疏效应。结果表明密度制约稀疏机制调节了样地大部分物种，是古田山亚热带森林群落物种多样性维持的重要机制。同时，密度制约稀疏效应主要发生在局部尺度上，与同种短距离聚集结果一致。另外，密度制约稀疏效应更易于影响丰富种(24公顷样地内个体数>1000)的种群结构。 Janzen-Connell假说的距离制约模型认为繁殖体制约后代更新成功，导致成年树个体间距增大，并得到众多的野外观察证明。然而，在大尺度的森林样地研究中，没有发现这个效应广泛存在。本研究采用独立性零模型分析了不同生活史阶段在空间上的关联性，特别是成年树和幼树、小树的关联性，反过来推演是否成年树对后代的距离制约驱动了种群分布的空间动态。综合分析古田山64个物种的不同径级阶段的空间关联性，同时参照Condit 等(1992，1994)的研究结果：成年树对后代的距离制约效应在小于5m的尺度上发生强烈。有20个物种（31.3%）的更新体聚集密度最高点在离成年树≥5m的距离上，加上21个物种的更新体与成年树的关联性成相互排斥和随机分布，64个被检验的物种中有41(64.1%)个物种表现了Janzen-Connell 假说的繁殖体对后代的距离制约效应。同时，54(84.4%)个物种的小树成为新的成年树，出现在成年体周围小于5m的距离内的比例最高。结果表明这个效应提高成年树的间距是有限的，然而，它仍然调节了样地内大部分物种的分布格局，促进了物种共存。 同种密度制约调节建成树木（胸径≥1cm）的空间结构得到很好的研究。然而最近的研究表明：病菌不仅在同种个体之间传播，同时也在近缘物种之间传播。因此，只包括同种个体的密度制约模型可能大大低估了密度制约效应的作用。本研究分析了古田山24 公顷内159 个物种。运用平均谱系多样性指数(APd) 和最近分类谱系多样性指数(NTPd)检验随着目标个体径级的增加系统发育结构变化的趋势。研究发现，在15、20、30m 的尺度上，APd 指数都随着生长阶段的增加而显著提高，在10、15、20、30m 的尺度上，NTPd 随着生长阶段的增加而显著提高；在5m 的尺度上，谱系多样性与生长阶段不存在显著关联性，这些结果表明谱系多样性制约与取样尺度相关。在DBH >30 cm 生长阶段， APd 下降，NTPd 上升，说明谱系多样性制约加大老树之间的谱系距离，但是由于类似的生境偏好，又倾向于聚集在类似的生境。 本研究的结果表明同种和近缘种的密度制约是亚热带常绿阔叶林生物多样性群落水平上重要的维持机制，为Janzen-Connell 假说提供了支持；同时，生境异质性和局部扩散能在维持森林物种多样性中发挥重要作用。

Oxidative damage in unfertilized eggs of Chinese rare minnow (Gobiocypris rarus) exposed to nonylphenol

In the present study, female Chinese rare minnows (Gobiocypris rarus) were used as in vivo models and exposed to nonylphenol (NP) at concentrations of 1 to 200 mu g/L for 21 d under semistatic conditions. Molecular biomarkers of oxidative stress were measured in unfertilized eggs and included reactive oxygen species (ROS), lipid peroxidation products (thiobarbituric acid-reactive substances [TBARS] and protein carbonyl), superoxide dismutase activity, and glutathione. Cathepsin D activity as an indicator of egg viability also was assayed. Nonylphenol induced ROS formation in unfertilized eggs in all exposed groups compared to the controls. The levels of protein carbonyl and TBARS in unfertilized eggs were significantly increased (p < 0.05) at 10 to 200 and 100 to 200 mu g/L, respectively. Good positive correlations were shown between ROS induction and levels of TBARS and protein carbonyl in eggs (R = 0.918, p < 0.05 and R = 0.784, p < 0.05, respectively). Superoxide dismutase activity in eggs was significantly inhibited (p < 0.05) in the 50 to 200 mu g/L exposure groups. Glutathione levels in eggs were significantly depleted (p < 0.05) at 100 to 200 mu g/L concentrations. In addition, ROS induction resulted in oxidative damage to lipid and protein in chorions. Significant reductions (p < 0.05) of the protein and lipid contents in chorions were both found in the 50 to 200 mu g/L exposure groups. A previous study found that NP exposure could lead to chorion thinning in zebra fish. Thus, the reductions in protein and lipid contents in chorion could be the reason for chorion thinning by NP exposure. Meanwhile, cathepsin D activity was significantly inhibited (p < 0.05) in all exposure groups. The results demonstrated that NP-induced oxidative stress could damage the chorion of unfertilized eggs and lead to a decline in gamete quality in female Chinese rare minnow.

Direct Wafer Bonding Technology employing vacuum-cavity pre-bonding

A novel low temperature direct wafer bonding technology employing vacuum-cavity pre-bonding is proposed and applied in bonding of InGaAs/Si couple wafers under 300 degrees C and InP/GaAs couple wafers under 350 degrees C. Aligning accuracy of 0.5 mu m is achieved. During wafer bonding process the pressure on the couple wafers is 10MPa. The interface energy is sufficiently high to allow thinning of the wafers down from 350um to about 100um. And the tensile strength test indicates the bonding energy of bonded samples is about equal to the bonded samples at 550 degrees C.

基于数学形态学的联机手写字符识别去噪方法

手写输入时由于笔尖抖动等原因产生了大量噪声,有效地去除噪声是手写识别的前提和关键。根据联机手写识别中手写体字符形态的特性,分析了手写时由于各种原因而产生的噪声,运用数学形态学中膨胀、腐蚀、细化等基本运算,提出了一种将数学形态学应用于联机手写识别预处理的方法,该方法可以有效地消除大量的冗余信息。测试结果表明,提出的方法可行,具有很好的鲁棒性,可以配合其他方案应用于各种联机手写字符识别中。

间伐对仁用杏园土壤理化性质及生长结果的影响

为了探讨密闭仁用杏园衰败的原因,采用常规的方法研究了间伐对仁用杏园土壤养分、水分及树体生长等方面的影响。结果表明:间伐减小了土壤容重,略微增加了土壤孔隙度;间伐显著提高了0-40 cm土层土壤有机质、0-20 cm土层土壤全氮,略微提高了0-20 cm土层土壤全磷;间伐显著提高了0-80 cm土层土壤速效氮、0-40 cm土层土壤速效磷和0-60 cm土层土壤速效钾,且间伐强度越大土壤养分越高;间伐显著提高了0-500cm土层土壤水分,在干旱的春季、夏季优为显著,且间伐强度越大,土壤水分越高;间伐显著促进了仁用杏生长,提高了坐果率和杏仁产量。白于山山区仁用杏间伐后密度应为167~222株/hm2。

Non-modal instabilities of two-dimensional disturbances in plane Couette flow of a power-law fluid

Instabilities of fluid flows have traditionally been investigated by normal mode analysis, i.e. by linearizing the equations of flow and testing for unstable eigenvalues of the linearized problem. However, the results of eigenvalue analysis agree poorly in many cases with experiments, especially for shear flows. In this paper we study the instabilities of two-dimensional Couette flow of a polymeric fluid in the framework of non-modal stability theory rather than normal mode analysis. A power-law model is used to describe the polymeric liquid. We focus on the response to external excitations and initial conditions by examining the pseudospectra structures and the transient energy growths. For both Newtonian and non-Newtonian flows, the results show that there can be a rather large transient growth even though the linear operator of Couette flow has no unstable eigenvalue. The effects of non-Newtonian viscosity on the transient behaviors are examined in this study. The results show that the "shear-thinning/shear-thickening" effect increases/decreases the amplitude of responses to external excitations and initial conditions. (C) 2010 Elsevier B.V. All rights reserved.

川西亚高山针叶林主要针叶树种年轮生态学研究

米亚罗地区是四川西部较为典型的亚高山针叶林区域之一。为建立该地区主要针叶树种岷江冷杉、云杉、紫果云杉和红杉的年轮宽度年表资料，了解不同海拔高度岷江冷杉原始林和不同恢复过程的人工针叶林及次生混交林树木径向生长规律，结合样地调查，用生长锥钻取了树木芯样做年轮生态学分析。芯样经过标准化程序固定和打磨抛光后，用WinDENDRO图像分析系统测量年轮宽度序列，用COFECHA程序交叉定年和控制测量数据质量，用ARSTAN程序建立了4个主要针叶树种的地区年表和不同海拔高度岷江冷杉林及人工针叶林和次生混交林针叶树的样地年表。 4个主要针叶树种年轮宽度年表的平均敏感度低于0.2，而其晚材宽度年表都具相对较高的平均敏感度。早材宽度与年轮总宽度标准化年表间的相关系数均在0.9以上；晚材宽度与年轮总宽度标准化年表间的相关系数则种间差异较大，红杉的最高，岷江冷杉的最低。岷江冷杉晚材宽度与年轮总宽度的相关性从1970年以后明显下降，而其他种的相关系数则随时间变化较小。树种之间标准化年表显著正相关，而云杉与紫果云杉和红杉与岷江冷杉之间相关系数明显较高。年表序列的第1主分量表达了4个树种树木共同径向生长变化格局；第2至第4主分量分别表达了云杉属和冷杉属、常绿针叶树种和落叶针叶树种以及云杉和紫果云杉树木径向生长变化差异。 不同海拔高度的8个岷江冷杉样地年轮宽度年表序列敏感度大体上随海拔高度升高而降低。各样地早材宽度与年轮总宽度年表之间的相关系数均在0.9以上，且随海拔高度变化不大；晚材宽度与年轮总宽度之间的相关系数随海拔高度的变化较大，并有随海拔升高而降低的趋势。样地年表序列之间相关系数差异很大，高海拔样地年表间多为显著正相关；低海拔样地年表间的相关系数变化不一；高海拔和低海拔样地年表之间相关性较差，且多不显著。样地年表的第1主分量能解释年表序列总方差的37.5%，反映了不同海拔高度岷江冷杉林木共同的径向生长变化格局；第2和第3主分量分别解释总方差的24.5%和18.2%，表现出明显的高海拔和低海拔样地树木间不同的径向生长变化，除一些样地例外，它们一般与低海拔样地年表有正相关，与高海拔样地年表有负相关。在那些另外的样地，海拔以外的其他因素可能也影响了树木径向生长变化。不同海拔高度样地林木的生长抑制和生长释放频率在不同时期表现出较大的差异，表明了不同的干扰历史和林木补充时间。 人工针叶林和次生混交林各样地林木早材宽度与其年轮总宽度年表之间相关系数均高达0.9以上；晚材宽度与年轮总宽度年表之间也都显著正相关，但人工针叶林样地的明显较高。样地年表序列之间的相关关系表现为，林分起源和经营管理相似的样地年表之间的相关系数明显较高，如人工针叶林与人工针叶林尽管树种不同，但样地年表之间显著正相关，而与次生混交林样地年表间关系不显著；反之亦然。综合比较各项生长参数及不同时期的树木径向生长速率，人工针叶林树木的胸径增长至少在40年以内是优于次生混交林的同种（或不同种）针叶树的。不同样地林木生长释放和生长抑制及人工针叶林树木胸高断面积增长分析表明，除严重的人为干扰外，林分郁闭后林木密度过大是造成高频率生长抑制的主要原因，在林分发育的适当时期通过抚育间伐等措施调控林分密度，是保证林木胸高断面积在一定时期内保持较高的连年增长的关键。日本落叶松作为引进的树种，在海拔3100 m左右种植表现良好，近30年来各项生长指标均高于林龄相近的云杉人工林，因此，适当用其作为川西亚高山针叶林采伐迹地快速恢复是合理的。 Miyaluo area is one of the typical regions covered by subalpine coniferous forests in western Sichuan province of southwestern China. To develop the regional tree-ring width chronology series for the dominant conifers such as Abies faxoniana, Picea asperata, P. purpurea and Larix potaninii, and to understand the radial growth patterns of conifers in Abies faxoniana natural forest stands at different altitudes, and in coniferous plantations and natural regenerated mixed stands in their different restoring processes as well, increment cores were sampled in the field together with conventional plots investigations for dendroecological analyses. After the increment cores being prepared according to standard procedures, the ring widths (total-ring and intra-ring widths) were measured with a WinDENDRO image-analysis system, and the measured tree-ring sequences were crossdated and quality-controlled with the software COFECHA. Using the software ARSTAN, we developed tree-ring width based chronology series of the four dominant conifers, eight site-specific Abies faxoniana chronologies, and seven site-specific chronologies of conifers in coniferous plantations and natural regenerated mixed stands. Mean sensitivities for total ring width chronologies of the four sampled dominant conifers were all below 0.2, while those for the latewood width chronologies of the same species were relatively much higher. Correlation coefficients between standard earlywood and total ring width chronologies of the four conifers were all above 0.9, but those between standard latewood and total ring width chronologies exhibited differences among species, with the coefficient of Larix potaninii the highest and that of Abies faxoniana the lowest. Correlation coefficients between latewood and total ring width of A. faxoniana obviously decreased from 1920-1970 for successive 50-year segments with 10-years lag analyses, though the same for the other three species changed unnoticeably with time. Tree-ring standard chronologies among species showed significant positive correlations, with the correlation coefficients between chronologies of Picea asperata and P. purpurea, and of Larix potaninii and Abies faxoniana relatively much higher. The first principal component of tree-ring chronologies represented the common radial growth patterns of the four conifers in Miyaluo area. The second, third and fourth PCs expressed the differences in radial growth responses for the genus Picea and Abies, for the evergreen and deciduous confers, and for the two species of the genus Picea, respectively. In general, mean sensitivities of the eight Abies faxoniana site-specific tree-ring width chronologies decreased with increasing altitude. The correlation coefficients between earlywood and total ring width chronologies for all sites reached 0.9, which did not change much with altitude; but those between latewood and total ring width chronologies diversified, with a decreasing tendency from lower altitudinal sites to higher altitudinal sites. Correlation coefficients among site chronologies varied considerably, with significant positive correlations among higher site chronologies, mixed results among lower site chronologies, and poor and insignificant correlations between chronologies of higher site and lower site. The first PC, which represents 37.5% of the total variance, reflected a common radial growth response at sites of different altitudes, and it showed a tendency of explaining more variance with increasing altitude. The second and the third PCs contributed to 24.5% and 18.2% of the total variance, respectively, exhibiting distinctive differences in radial growth responses between low- and high-altitudinal sites. With some exceptions, the radial growth represented by the second and third PCs had a positive correlation with that at the low-altitudinal sites and a negative correlation with that at the high-altitudinal sites. For those exceptional sites, factors other than altitude might also play a role in affecting tree-ring growth variations. Trees in stands of different altitudes showed great differences in frequencies of growth suppressions and releases through times, suggesting different disturbance histories and periods when trees recruiting to the canopy. Correlation coefficients between earlywood and total ring width chronologies for all sites of coniferous plantations and natural regenerated mixed stands were also above 0.9; and the same between latewood width and total ring width chronologies all positively correlated, too, with the coefficients of the coniferous plantations obviously much higher. Correlations among site chronologies showed that the coefficients among sites with similar stand origin and management regimes were much higher than those among sites with different stand origin and management regimes. For example, significant positive correlations were found for chronologies among different coniferous plantations, irrespective of species differences; while insignificant correlations between chronologies of the same conifer from a coniferous plantation and a natural regenerated mixed stand, and vise versa. Integrative comparisons of different tree growth parameters and radial growth rates at different stages indicated that the diameter at breast height (DBH) increments for trees in coniferous plantations were faster than those for trees of the same (or different) species in the natural regenerated mixed stands, at least within their first 40 years of stand development. Analyses of growth releases and suppressions, and basal area increments of trees in different stands demonstrated that over-dense individuals after canopy closure was the main factor resulting in high frequencies of radial growth suppressions, with some exceptions of severe man-made disturbances. Therefore, to ensure a continuous basal area current annual increment in certain periods, tree density controlling through thinning in due time during the stand development process are necessary. It should be mentioned that, as an introduced conifer to Miyaluo area, Larix kaempferi grew quite well at altitude of ca. 3100 m after planting in 1970s. In their near 30 years of stand development, Larix kaempferi trees exhibited faster growth in various parameters than Picea asperata trees of the similar stand age did. Thus we think it reasonable to use Larix kaempferi as a fast restoring species at appropriate sites of cutting blanks of subalpine coniferous forests in western Sichuan.

Composition dependence of the crystallization behavior and morphology of the poly(ethylene oxide)-poly(epsilon-caprolactone) diblock copolymer

The crystallization behavior and morphology of the crystalline-crystalline poly(ethylene oxide)-poly(epsilon-caprolactone) diblock copolymer (PEO-b-PCL) was studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), small-angle X-ray scattering (SAXS), and hot-stage polarized optical microscope (POM). The mutual effects between the PEO and PCL blocks were significant, leading to the obvious composition dependence of the crystallization behavior and morphology of PEO-b-PCL. In this study, the PEO block length was fixed (M-n = 5000) and the weight ratio of PCL/PEO was tailored by changing the PCL block length. Both blocks could crystallize in PEO-b-PCL with the PCL weight fraction (WFPCL) of 0.23-0.87. For the sample with the WFPCL of 0.36 or less, the PEO block crystallized first, resulting in the obvious confinement of the PCL block and vice versa for the sample with WFPCL of 0.43 or more. With increasing WFPCL, the crystallinity of PEO reduced continuously while the variation of the PCL crystallinity exhibited a maximum. The long period of PEO-b-PCL increased with increasing WFPCL from 0.16 to 0.50 but then decreased with the further increase of WFPCL due to the interaction of the respective variation of the thicknesses of the PEO and PCL crystalline lamellae.

Isothermal crystallization kinetics of PEO in poly(ethylene terephthalate)-poly(ethylene oxide) segmented copolymers. I. Effect of the sofi-block length

The isothermal crystallization kinetics of poly(ethylene oxide) (PEO) block in two poly(ethylene terephthalate) (PET)-PEO segmented copolymers was studied with differential scanning calorimetry. The Avrami equation failed to describe the overall crystallization process, but a modified Avrami equation, the Q equation, did. The crystallizability of the PET block and the different lengths of the PEO block exerted strong influences on the crystallization process, the crystallinity, and time final morphology of the PEO block. The mechanism of nucleation and the growth dimension of the PEG block were different because of the crystallizability of time PET block and the compositional heterogeneity. The crystallization of the PEO block was physically constrained by the microstructure of time PET crystalline phase, which resulted in a lower crystallization rate. However, this influence became weak with the increase in the soft-block length. (C) 2000 John Wiley & Sons, Inc.

Electrochemical studies of lipophilic ion transport through BLM. The influence of sterols on its transport

Cyclic voltammetry was employed to study the influence of sterols on the lipophilic ion transport through the BLM. The mole fraction of the sterols (cholesterol, oxidized cholesterol). as referred to total lipid, was varied in a range of 0-0.8. Data demonstrate that a thin-layer model is suitable to this BLM system. By this model, the number of charges transported per lipophilic ion, the concentration of the ion in the membrane bulk phase and the aqueous/membrane phase partition coefficient could be calculated. These parameters proved that sterols had an obvious influence on the lipophilic ion transport. Cholesterol had a stronger influence on the ion transport than oxidized cholesterol. Its incorporation into egg lecithin membranes increased the partition coefficient beta of the ion up to more than 3-fold. Yet, oxidized cholesterol incorporated into egg lecithin membranes only increased the beta up to less than 2-fold, and the beta had no great variation at different oxidized cholesterol mole fractions. The higher beta obtained was partly due to the trace amount of solvent existing in the core of the lipid bilayers. At the different sterol mole fractions, combining the change of beta with the change of peak current, we also concluded that sterols had somewhat inhibiting effect on the ion transport at the higher sterols mole fraction (>0.4). These results are explained in terms of the possible change of dipole potential of the membrane produced by sterols and the decrease of the membrane fluidity caused by the condensation effect of sterols and the thinning effect caused by sterols. The substituting group (in the oxidized cholesterol) had some inhibiting effects on the ion transport at higher mole fractions (oxidized cholesterol mole fraction >0.4).