Measurements of surface tension of organic solvents using a simple microfabricated chip

Measurement of the surface tension of organic solvents using a simple microfabricated chip was developed based on the principle of differential capillary rise. The theory, design, fabrication, and characterization of the chip were described. A two-step etching technique was used to fabricate a number of microchannels with different dimensions on the glass substrate. Capillarity was used to introduce liquid samples, which requires no power supply or actuator to be applied in the experiment. Liquid in different microchannels generated capillary rise with different heights, by which surface tension maybe calculated. Seven common organic solvents, ethanol, acetone, acetonitrile, dichloromethane, hexane, methanol, and toluene, were tested at room temperature. The surface tension of ethanol at different temperatures was measured over the range of 5-45 degrees C. Relative standard deviation for seven replicate measurements at each temperature is 0.20-0.74%. The results showed good reproducibility and acceptable precision compared with traditional methods. Very low reagent consumptions and short analysis time were achieved using this simple method.     

Contour into texture: information content of surface contours and texture flow

Both surface contours and texture patterns can provide strong cues to the three-dimensional shape of a surface in space. Many of the most perceptually salient texture patterns have a strong flowlike structure, resulting from the directional nature of the surface textures from which they project. Under the minimal assumption that an oriented surface texture is homogeneous, the texture flow on a developable surface can be shown to follow parallel geodesics of the surface. The geometry of texture flow is therefore equivalent to that of an important class of surface contours: those that project from parallel geodesics of a developable surface. I derive a set of differential equations that support the estimation of surface shape from geodesic surface contours under spherical perspective, for both parallel and nonparallel contours. For perfectly oriented textures, the equations apply directly to the integrated flow lines in a texture image. For weakly oriented textures, perspective projection distorts the projected orientation of flow lines away from the idealized case of pure contours; however, simulations show that for a large class of textures, these distortions will be small and limited largely to extreme surface poses. The geometrical analysis, along with a number of phenomenal demonstrations and psychophysical results, suggests that the human visual system co-opts shape from contour mechanisms to estimate surface shape from texture flow.     

纹理分析在肝脏超声图像组织定征中的应用

现代超声医学影像通过研究超声传播中与生物组织相互作用后携带的图像纹理信息进行组织定征,为临床各学科疾病的检查、诊断和介入治疗提供了一条重要手段.本文在对目前文献进行分析和综合的基础上,首先阐述了图像纹理分析的常用方法,然后对纹理分析在肝脏超声图像中的应用进行了介绍,最后讨论了存在的问题及研究展望.     

The modulation of surface texture for single-crystalline Si solar cells using calibrated silver nanoparticles as a catalyst

We have employed Ag nanoparticles with calibrated size as catalysts to modulate the surface texture of single-crystalline Si surfaces for reducing sunlight reflectivity. Both experiments and theoretical analysis have proved that a well-organized microporous structure on the pyramids can be obtained by optimizing the size of Ag nanoparticles and the texturing time, and the Si wafer with such structures can effectively reduce the reflectivity of sunlight. However, based on the conventional cell fabrication process, the performance of silicon solar cells with such microporous structures gets degraded. It is closely associated with the strong surface recombination and the high phosphorus diffusion barrier induced by the microporous textures. These results are interesting for us to understand the application of nanotechnology on the silicon solar cell.     

Measurements of surface magnetic fields of perpendicular and longitudinal magnetic recorded transitions using a magnetoresistive transducer

Quasi-static recording experiments employing a hybrid single-pole-type write head and a vertical magnetoresistive transducer (MRT) read head are presented. The MRT is shown to be able to measure asymmetries of the remanent magnetization of transitions recorded in perpendicular and longitudinal media. The effects of varying the write field angle by adjusting the write shim placement with respect to the auxiliary pole is shown to be useful in determining the resultant remanent magnetization. Dynamic recording responses correlate with the quasi-static measurements. A model of recorded transitions is presented which combines in-plane arctangent and vertical complementary arctangent remanent magnetization distributions.     

基于CFD的新型表面织构仿真分析

摩擦、磨损是导致运动副失效的主要因素,而表面织构化是一种改善运动副摩擦学性能的有效手段。为此,在传统圆形和三角形表面织构的基础上,设计了几种新型表面织构,并分别建立其二维和三维模型;利用CFD（computational fluid dynamics,计算流体力学）软件Fluent对新型表面织构进行仿真分析,研究了表面织构的几何参数（圆弧状凸起高度和三角形形状）和分布角度对其表面的速度场和承载力的影响。结果表明：对于圆形表面织构,底部有圆弧状凸起的普遍具有更大的承载力,且当凸起高度为0.6 mm时,其承载力达到最大;对于三角形表面织构,所设计的新型三角形Ⅰ表面织构的承载力较大;表面织构的分布角度对其承载力的影响显著,当分布角度为75°时,表面织构的承载力最大。研究结果可为运动副表面织构的设计及优化提供一定的理论参考。     

Temperature mapping near the surface of ultrasound transducers using susceptibility- compensated magnetic resonance imaging

Magnetic resonance imaging (MRI)-based temperature mapping very close to the surface of an ultrasound transducer is not possible due to the large magnetic susceptibility-induced image artifacts that arise from the materials used in transducer construction. Here, it is shown in phantoms that "susceptibility-compensated" MRI sequences can be used to measure thermal increases ~1 mm from the surface of a 4-element cymbal array transducer, which has been used widely for noninvasive transdermal drug delivery. The estimated temperatures agree well with those measured using thermocouples.     

Three-dimensional surface texture of Portland cement concrete pavements containing nanosilica

Pavement surface texture is critical to tire/pavement interaction. Texture characteristics of concrete containing nanosilica pavement surface has not yet been directly investigated, although researchers have found that nanosilica improved pavement friction values and durability. Specimens with various nanosilica content are tested for three-dimensional (3D) texture height maps which are decomposed using discrete wavelet transform for the calculation of 3D texture indices for macrotexture and microtexture. It is found that 3D texture indices increase correspondingly with the increment of nanosilica content. Significant relationship with R ² values between 0.80 and 0.99 is found between various texture indices and nanosilica content. The increased texture amplitude indicates enhanced pavement friction and then safety. The increment of core material volume implies more texture in the core region, which indicates better longevity of texture. The findings of this research agree with the results of other studies that nanosilica increased the abrasion resistance and frictional property of concrete surface.     

Refractive Index Measurements using a CCD

We measure the refractive index of materials using a CCD camera with a laser beam profiler in the familiar Brewster's angle experiment. This allows us to isolate quickly and accurately the Brewster's angle close to the resolution of the sample rotation stage. The uncertainty in the index of refraction measurement is similar to that of the standard minimum-deviation technique.     

Engineering the surface texture and shape of channels in ceramic substrates

Ceramic/ceramic joining can transform surface channels on a ceramic subcomponent into an interior channel. Interior channels have a number of potential uses in advanced ceramic applications, including application as conduits of a variety of fluids, such as fuel, medicine, or cooling fluids. For cooling fluids in particular, the surface texture and shape of the channel can greatly affect its heat transfer and fluid flow characteristics. This paper explores means of “engineering” the surface textures and shapes of such channels, including the fabrication of channels with circular and non-circular cross-sections as well as channels with smooth or textured walls (and channels with a combination of smooth and textured regions). The microstructure of the channels is analyzed using laser scanning confocal microscopy (LSCM). Although LSCM has been used extensively in biological studies, this study is one of the first studies to apply LSCM as a tool to characterize three-dimensional shapes and textures in ceramic materials.     

Computer-generated holograms for three-dimensional surface objects with shade and texture

Digitally synthetic holograms of surface model objects are investigated for reconstructing three-dimensional objects with shade and texture. The objects in the proposed techniques are composed of planar surfaces, and a property function defined for each surface provides shape and texture. The field emitted from each surface is independently calculated by a method based on rotational transformation of the property function by use of a fast Fourier transform (FFT) and totaled on the hologram. This technique has led to a reduction in computational cost: FFT operation is required only once for calculating a surface. In addition, another technique based on a theoretical model of the brightness of the reconstructed surfaces enables us to shade the surface of a reconstructed object as designed. Optical reconstructions of holograms synthesized by the proposed techniques are demonstrated.     

驱动速度对表面粗糙度参数测量准确度的影响

该文针对轮廓法M制触针式表面粗糙度测量仪器由于其驱动速度变化可能引起表面粗糙度评定参数测量准确度受损的问题，从参数的定义、轮廓的滤波特性、轮廓的畸变等方面作出了较为详细的分析和讨论，同时也提出了改善驱动机构速度特性和仪器信号处理方法的一些思路和建议。     

齿面粗糙纹理方向对齿轮润滑效应的影响

 不同的机械加工方法会形成相异的表面粗糙纹理.为了探析不同粗糙纹理对齿轮传动润滑效应之影响,基于实际测量所获得的一系列粗糙度数值,进行了45组数值计算.计算结果显示：当粗糙度均方根值σ≤0.15 μm时,粗糙度对齿面油膜厚度与接触应力影响甚微;当σ>0.15 μm后,随着σ的增大,纵、横向纹理粗糙齿面接触应力均呈线性规律增加,但前者的接触应力始终大于后者.尤其是当σ≥0.55 μm时,与光滑齿面相比,纵、横向纹理粗糙齿面接触应力分别增大90%和80%;与此同时,纵向纹理膜厚值减低40%,而横向纹理膜厚值增大80%以上.在此基础上,针对纵、横向两种粗糙纹理齿面,分别建立了轮齿接触应力与齿面粗糙度之间的回归方程.最后,给出了横向纹理粗糙齿面的润滑效果要优于纵向纹理粗糙齿面的研究结论.     

Fiber texture and surface composition of evaporated gold films on quartz

The fiber texture, surface composition and homogeneity of polycrystalline films of gold 300–2000 Å thick evaporated onto quartz in the pressure range from 1.5 × 10⁻² to 2 × 10⁻⁷ Pa were investigated by means of X-ray diffraction, electron microscopy, Auger electron spectroscopy and gas sorption experiments. No qualitative differences are observed between the films characterized here and previous results reported for glass substrates: a (111) fiber orientation is observed and is enhanced as the substrate temperature, during or after the deposition, is increased. The percentage of gold present at the surface and the surface homogeneity are more sensitive to the cleaning and outgassing procedure than to the actual pressure during deposition. The uniformity of the quartz substrate has little influence on the surface homogeneity of the gold film.     

Use of biomimetic hexagonal surface texture in friction against lubricated skin

Smooth contact pads that evolved in insects, amphibians and mammals to enhance the attachment abilities of the animals'' feet are often dressed with surface micropatterns of different shapes that act in the presence of a fluid secretion. One of the most striking surface patterns observed in contact pads of these animals is based on a hexagonal texture, which is recognized as a friction-oriented feature capable of suppressing both stick–slip and hydroplaning while enabling friction tuning. Here, we compare this design of natural friction surfaces to textures developed for working in similar conditions in disposable safety razors. When slid against lubricated human skin, the hexagonal surface texture is capable of generating about twice the friction of its technical competitors, which is related to it being much more effective at channelling of the lubricant fluid out of the contact zone. The draining channel shape and contact area fraction are found to be the most important geometrical parameters governing the fluid drainage rate.     

Field-induced surface texture in 3He-A in the presence of superflow

The effect of superflow on the magnetic field-induced surface texture in ³He-A is studied theoretically. We find that in the presence of small superflow the surface texture becomes nonplanar. The NMR satellite frequencies associated with the surface texture are obtained.Supported by National Science Foundation grant No. DMR76-21032.     

Measurements of the infrared emissivity of a wind-roughened sea surface

Spectral statistical-analysis techniques were developed and applied to high-spectral-resolution infrared measurements of the sea surface. The effective incidence angle of a ship-borne instrument in typical at-sea conditions was found to introduce errors of up to 0.7 K in sea-surface temperature retrievals at a 55 degrees view angle. The sea-surface emissivity was determined over the 8-12-microm window at view angles of 40 degrees and 55 degrees and at wind speeds up to 13 ms(-1). The emissivity was found to increase in magnitude with increasing wind speed, rather than decrease, as predicted by widely used parameterizations. Use of these parameterizations can cause significant bias in remote sensing of sea-surface temperature in noncalm conditions.