WorldWideScience

Sample records for surface texture patterns

  1. A new procedure for characterizing textured surfaces with a deterministic pattern of valley features

    DEFF Research Database (Denmark)

    Godi, Alessandro; Kühle, A; De Chiffre, Leonardo

    2013-01-01

    In recent years there has been the development of a high number of manufacturing methods for creating textured surfaces which often present deterministic patterns of valley features. Unfortunately, suitable methodologies for characterizing them are lacking. Existing standards cannot in fact...

  2. A plateau–valley separation method for textured surfaces with a deterministic pattern

    DEFF Research Database (Denmark)

    Godi, Alessandro; Kühle, Anders; De Chiffre, Leonardo

    2014-01-01

    The effective characterization of textured surfaces presenting a deterministic pattern of lubricant reservoirs is an issue with which many researchers are nowadays struggling. Existing standards are not suitable for the characterization of such surfaces, providing at times values without physical...... division of the two regions, which can be studied separately according to their specific function. The case of a turned multifunctional profile is presented depicting the lacks in efficacy of standardized methods and therefore studied with this new methodology. Limitations of the method are eventually...

  3. Rational design of organic semiconductors for texture control and self-patterning on halogenated surfaces

    KAUST Repository

    Ward, Jeremy W.

    2014-05-15

    Understanding the interactions at interfaces between the materials constituting consecutive layers within organic thin-film transistors (OTFTs) is vital for optimizing charge injection and transport, tuning thin-film microstructure, and designing new materials. Here, the influence of the interactions at the interface between a halogenated organic semiconductor (OSC) thin film and a halogenated self-assembled monolayer on the formation of the crystalline texture directly affecting the performance of OTFTs is explored. By correlating the results from microbeam grazing incidence wide angle X-ray scattering (μGIWAXS) measurements of structure and texture with OTFT characteristics, two or more interaction paths between the terminating atoms of the semiconductor and the halogenated surface are found to be vital to templating a highly ordered morphology in the first layer. These interactions are effective when the separating distance is lower than 2.5 dw, where dw represents the van der Waals distance. The ability to modulate charge carrier transport by several orders of magnitude by promoting "edge-on" versus "face-on" molecular orientation and crystallographic textures in OSCs is demonstrated. It is found that the "edge-on" self-assembly of molecules forms uniform, (001) lamellar-textured crystallites which promote high charge carrier mobility, and that charge transport suffers as the fraction of the "face-on" oriented crystallites increases. The role of interfacial halogenation in mediating texture formation and the self-patterning of organic semiconductor films, as well as the resulting effects on charge transport in organic thin-film transistors, are explored. The presence of two or more anchoring sites between a halogenated semiconductor and a halogenated self-assembled monolayer, closer than about twice the corresponding van der Waals distance, alter the microstructure and improve electrical properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Laser textured surface gradients

    Science.gov (United States)

    Ta, Van Duong; Dunn, Andrew; Wasley, Thomas J.; Li, Ji; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Esenturk, Emre; Connaughton, Colm; Shephard, Jonathan D.

    2016-05-01

    This work demonstrates a novel technique for fabricating surfaces with roughness and wettability gradients and their subsequent applications for chemical sensors. Surface roughness gradients on brass sheets are obtained directly by nanosecond laser texturing. When these structured surfaces are exposed to air, their wettability decreases with time (up to 20 days) achieving both spatial and temporal wettability gradients. The surfaces are responsive to organic solvents. Contact angles of a series of dilute isopropanol solutions decay exponentially with concentration. In particular, a fall of 132° in contact angle is observed on a surface gradient, one order of magnitude higher than the 14° observed for the unprocessed surface, when the isopropanol concentration increased from 0 to 15.6 wt%. As the wettability changes gradually over the surface, contact angle also changes correspondingly. This effect offers multi-sensitivity at different zones on the surface and is useful for accurate measurement of chemical concentration.

  5. Quantitative Characterisation of Surface Texture

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Lonardo, P.M.; Trumpold, H.

    2000-01-01

    This paper reviews the different methods used to give a quantitative characterisation of surface texture. The paper contains a review of conventional 2D as well as 3D roughness parameters, with particular emphasis on recent international standards and developments. It presents new texture...

  6. Laser surface texturing: chosen problems

    Science.gov (United States)

    Antoszewski, Bogdan; Sek, Piotr

    2013-01-01

    In modern machines for realization of goals like lubrication intesyfication, heat flow intensyfiacation, microflow simulation; more and more often surface texturing is used. It became possible due to develepment of technologies that use sources of concentrated energy stream like microlasers. The paper shows results of experimental investigation on seal rings made of silicon carbide. Experiments were conducted using seal rings without surface modifications and a seal rings with a geometrical surface textures made with Nd:Yag laser.

  7. EUROMET SUPPLEMENTARY COMPARISON - SURFACE TEXTURE

    DEFF Research Database (Denmark)

    Koenders, L.; Andreasen, Jan Lasson; De Chiffre, Leonardo

    At the length meeting in Prague in Oct. 1999 a new comparison was suggested on surface texture. The last comparison on this field was finished in 1989. In the meantime the instrumentation, the standards and the written standards have been improved including some software filters. The pilot...... laboratories for this supplementary comparison on surface texture are the Centre for Geometrical Metrology at the Technical University of Denmark and the Micro- and Nanotopography laboratory at the Physikalisch-Technische Bundesanstalt, Germany....

  8. Laser surface texturing of tool steel: textured surfaces quality evaluation

    Science.gov (United States)

    Šugár, Peter; Šugárová, Jana; Frnčík, Martin

    2016-05-01

    In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

  9. Surface texture metrology for high precision surfaces

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Gasparin, Stefania; Tosello, Guido

    2010-01-01

    This paper introduces some of the challenges related to surface texture measurement of high precision surfaces. The paper is presenting two case studies related to polished tool surfaces and micro part surfaces. In both cases measuring instrumentation, measurement procedure and the measurement...

  10. Surface texture metrology for high precision surfaces

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Gasparin, Stefania; Tosello, Guido

    2010-01-01

    This paper introduces some of the challenges related to surface texture measurement of high precision surfaces. The paper is presenting two case studies related to polished tool surfaces and micro part surfaces. In both cases measuring instrumentation, measurement procedure and the measurement re...

  11. High Power Picosecond Laser Surface Micro-texturing of H13 Tool Steel and Pattern Replication onto ABS Plastics via Injection Moulding

    Science.gov (United States)

    Otanocha, Omonigho B.; Li, Lin; Zhong, Shan; Liu, Zhu

    2016-03-01

    H13 tool steels are often used as dies and moulds for injection moulding of plastic components. Certain injection moulded components require micro-patterns on their surfaces in order to modify the physical properties of the components or for better mould release to reduce mould contamination. With these applications it is necessary to study micro-patterning to moulds and to ensure effective pattern transfer and replication onto the plastic component during moulding. In this paper, we report an investigation into high average powered (100 W) picosecond laser interactions with H13 tool steel during surface micro-patterning (texturing) and the subsequent pattern replication on ABS plastic material through injection moulding. Design of experiments and statistical modelling were used to understand the influences of laser pulse repetition rate, laser fluence, scanning velocity, and number of scans on the depth of cut, kerf width and heat affected zones (HAZ) size. The characteristics of the surface patterns are analysed. The process parameter interactions and significance of process parameters on the processing quality and efficiency are characterised. An optimum operating window is recommended. The transferred geometry is compared with the patterns generated on the dies. A discussion is made to explain the characteristics of laser texturing and pattern replication on plastics.

  12. Development of low friction snake-inspired deterministic textured surfaces

    Science.gov (United States)

    Cuervo, P.; López, D. A.; Cano, J. P.; Sánchez, J. C.; Rudas, S.; Estupiñán, H.; Toro, A.; Abdel-Aal, H. A.

    2016-06-01

    The use of surface texturization to reduce friction in sliding interfaces has proved successful in some tribological applications. However, it is still difficult to achieve robust surface texturing with controlled designer-functionalities. This is because the current existing gap between enabling texturization technologies and surface design paradigms. Surface engineering, however, is advanced in natural surface constructs especially within legless reptiles. Many intriguing features facilitate the tribology of such animals so that it is feasible to discover the essence of their surface construction. In this work, we report on the tribological behavior of a novel class of surfaces of which the spatial dimensions of the textural patterns originate from micro-scale features present within the ventral scales of pre-selected snake species. Mask lithography was used to produce implement elliptical texturizing patterns on the surface of titanium alloy (Ti6Al4V) pins. To study the tribological behavior of the texturized pins, pin-on-disc tests were carried out with the pins sliding against ultra-high molecular weight polyethylene discs with no lubrication. For comparison, two non-texturized samples were also tested under the same conditions. The results show the feasibility of the texturization technique based on the coefficient of friction of the textured surfaces to be consistently lower than that of the non-texturized samples.

  13. Using texture synthesis in fractal pattern design

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Traditional fractal pattern design has some disadvantages such as inability to effectively reflect the characteristics of real scenery and texture. We propose a novel pattern design technique combining fractal geometry and image texture synthesis to solve these problems. We have improved Wei and Levoy (2000)'s texture synthesis algorithm by first using two-dimensional autocorrelation function to analyze the structure and distribution of textures, and then determining the size of L neighborhood.Several special fractal sets were adopted and HSL (Hue, Saturation, and Light) color space was chosen. The fractal structure was used to manipulate the texture synthesis in HSL color space where the pattern's color can be adjusted conveniently. Experiments showed that patterns with different styles and different color characteristics can be more efficiently generated using the new technique.

  14. Quantitative Characterisation of Surface Texture

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Lonardo, P.M.; Trumpold, H.;

    2000-01-01

    This paper reviews the different methods used to give a quantitative characterisation of surface texture. The paper contains a review of conventional 2D as well as 3D roughness parameters, with particular emphasis on recent international standards and developments. It presents new texture...... characterisation methods, such as fractals, wavelets, change trees and others, including for each method a short review, the parameters that the new methods calculate, and applications of the methods to solve surface problems. The paper contains a discussion on the relevance of the different parameters...... and quantification methods in terms of functional correlations, and it addresses the need for reducing the large number of existing parameters. The review considers the present situation and gives suggestions for future activities....

  15. Separation Surfaces in the Spectral TV Domain for Texture Decomposition

    Science.gov (United States)

    Horesh, Dikla; Gilboa, Guy

    2016-09-01

    In this paper we introduce a novel notion of separation surfaces for image decomposition. A surface is embedded in the spectral total-variation (TV) three dimensional domain and encodes a spatially-varying separation scale. The method allows good separation of textures with gradually varying pattern-size, pattern-contrast or illumination. The recently proposed total variation spectral framework is used to decompose the image into a continuum of textural scales. A desired texture, within a scale range, is found by fitting a surface to the local maximal responses in the spectral domain. A band above and below the surface, referred to as the \\textit{Texture Stratum}, defines for each pixel the adaptive scale-range of the texture. Based on the decomposition an application is proposed which can attenuate or enhance textures in the image in a very natural and visually convincing manner.

  16. OPTIMIZED LOCAL TERNARY PATTERNS: A NEW TEXTURE MODEL WITH SET OF OPTIMAL PATTERNS FOR TEXTURE ANALYSIS

    Directory of Open Access Journals (Sweden)

    G. Madasamy Raja

    2013-01-01

    Full Text Available Texture analysis is one of the important as well as useful tasks in image processing applications. Many texture models have been developed over the past few years and Local Binary Patterns (LBP is one of the simple and efficient approach among them. A number of extensions to the LBP method have been also presented but the problem remains challenging in feature vector generation and comparison. As textures are oriented and scaled differently, a texture model should effectively handle grey-scale variation, rotation variation, illumination variation and noise. The length of the feature vector in a texture model also plays an important role in deciding the time complexity of the texture analysis. This study proposes a new texture model, called Optimized Local Ternary Patterns (OLTP in the spatial methods of texture analysis. The proposed texture model is based on Local Ternary Patterns (LTP, which in turn is based on LBP. A new concept called “Level of Optimality” to select the optimal set of patterns is discussed in this study. This proposed texture model uses only optimal patterns to extract the textural information from the digital images and thereby reducing the length of the feature vector. This proposed model is robust to image rotation, grey-scale transformation, histogram equalization and noise. The results are compared with other widely used texture models by applying classification tests to variety of texture images from the standard Brodatz texture database. Experimental results prove that the proposed texture model is robust to grey-scale variation, image rotation, histogram equalization and noise. Experimental results also show that the proposed texture model improves the classification accuracy and the speed of the classification process. In all tested tasks, the proposed method outperforms the earlier methods.

  17. Optical simulation of surface textured TCO using FDTD method

    Science.gov (United States)

    Elviyanti, I. L.; Purwanto, H.; Kusumandari

    2016-02-01

    The purpose of this research is simulating the transmittance of surface textured transparent conducting oxide (TCO) for Dye-Sensitized Solar Cell (DSSC) application. The simulation based on finite difference time domain (FDTD) was performed using the MatLab software for flat and pyramid surface textured TCO. Fluorine-doped tin oxide (FTO) and indium tin oxide (ITO) were used as TCO material. The transmittance simulation of flat TCO was compared to UV-Vis spectrophotometer measurement of real TCO to ensure the accuracy of the simulation. Then, the transmittance simulation of pyramid surface textures of TCO is higher than a flat one. It suggested that surface texturing enhance the path of light through dispersion and reflectance light by the pattern of the surface. This result indicates that surface textured increasing the transmittance of TCO through a complex light trapping mechanism which might be used to increase the light harvesting for DSSC application.

  18. Quantitative texture analysis of electrodeposited line patterns

    DEFF Research Database (Denmark)

    Pantleon, Karen; Somers, Marcel A.J.

    2005-01-01

    Free-standing line patterns of Cu and Ni were manufactured by electrochemical deposition into lithographically prepared patterns. Electrodeposition was carried out on top of a highly oriented Au-layer physically vapor deposited on glass. Quantitative texture analysis carried out by means of x...

  19. Quantitative texture analysis of electrodeposited line patterns

    DEFF Research Database (Denmark)

    Pantleon, Karen; Somers, Marcel A.J.

    2005-01-01

    Free-standing line patterns of Cu and Ni were manufactured by electrochemical deposition into lithographically prepared patterns. Electrodeposition was carried out on top of a highly oriented Au-layer physically vapor deposited on glass. Quantitative texture analysis carried out by means of x...

  20. Detection of surfaces for projection of texture

    Science.gov (United States)

    Molinier, Thierry; Fofi, David; Gorria, Patrick; Salvi, Joaquim

    2007-01-01

    Augmented reality is used to improve color segmentation on human's body or on precious no touch artefacts. We propose a technique based on structured light to project texture on a real object without any contact with it. Such techniques can be apply on medical application, archeology, industrial inspection and augmented prototyping. Coded structured light is an optical technique based on active stereovision which allows shape acquisition. By projecting a light pattern onto the surface of an object and capturing images with a camera, a large number of correspondences can be found and 3D points can be reconstructed by means of triangulation.

  1. Lizard-Skin Surface Texture

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1 The south polar region of Mars is covered seasonally with translucent carbon dioxide ice. In the spring gas subliming (evaporating) from the underside of the seasonal layer of ice bursts through weak spots, carrying dust from below with it, to form numerous dust fans aligned in the direction of the prevailing wind. The dust gets trapped in the shallow grooves on the surface, helping to define the small-scale structure of the surface. The surface texture is reminiscent of lizard skin (figure 1). Observation Geometry Image PSP_003730_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 14-May-2007. The complete image is centered at -85.2 degrees latitude, 181.5 degrees East longitude. The range to the target site was 248.5 km (155.3 miles). At this distance the image scale is 24.9 cm/pixel (with 1 x 1 binning) so objects 75 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 06:04 PM and the scene is illuminated from the west with a solar incidence angle of 69 degrees, thus the sun was about 21 degrees above the horizon. At a solar longitude of 237.5 degrees, the season on Mars is Northern Autumn.

  2. Staphylococcus epidermidis adhesion on hydrophobic and hydrophilic textured biomaterial surfaces.

    Science.gov (United States)

    Xu, Li-Chong; Siedlecki, Christopher A

    2014-06-01

    It is of great interest to use nano- or micro-structured surfaces to inhibit microbial adhesion and biofilm formation and thereby to prevent biomaterial-associated infection, without modification of the surface chemistry or bulk properties of the materials and without use of the drugs. Our previous study showed that a submicron textured polyurethane surface can inhibit staphylococcal bacterial adhesion and biofilm formation. To further understand the effect of the geometry of textures on bacterial adhesion as well as the underlying mechanism, in this study, submicron and micron textured polyurethane surfaces featuring ordered arrays of pillars were fabricated and modified to have different wettabilities. All the textured surfaces were originally hydrophobic and showed significant reductions in Staphylococcus epidermidis RP62A adhesion in phosphate buffered saline or 25% platelet poor plasma solutions under shear, as compared to smooth surfaces. After being subjected to an air glow discharge plasma treatment, all polyurethane surfaces were modified to hydrophilic, and reductions in bacterial adhesion on surfaces were subsequently found to be dependent on the size of the patterns. The submicron patterned surfaces reduced bacterial adhesion, while the micron patterned surfaces led to increased bacterial adhesion. The extracellular polymeric substances (EPS) from the S. epidermidis cell surfaces were extracted and purified, and were coated on a glass colloidal surface so that the adhesion force and separation energy in interactions of the EPS and the surface could be measured by colloidal probe atomic force microscopy. These results were consistent with the bacterial adhesion observations. Overall, the data suggest that the increased surface hydrophobicity and the decreased availability of the contact area contributes to a reduction in bacterial adhesion to the hydrophobic textured surfaces, while the availability of the contact area is the primary determinant factor

  3. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    K R Y Simha; Anirudhan Pottirayil; Pradeep L Menezes; Satish V Kailas

    2008-06-01

    Directionality of grinding marks influences the coefficient of friction during sliding. Depending on the sliding direction the coefficient of friction varies between maximum and minimum for textured surfaces. For random surfaces without any texture the friction coefficient becomes independent of the sliding direction. This paper proposes the concept of a friction tensor analogous to the heat conduction tensor in anisotropic media. This implies that there exists two principal friction coefficients $\\mu_{1,2}$ analogous to the principal conductivities $k_{1,2}$. For symmetrically textured surfaces the principal directions are orthogonal with atleast one plane of symmetry. However, in the case of polished single crystalline solids in relative sliding motion, crystallographic texture controls the friction tensor.

  4. Method of Direct Texture Synthesis on Arbitrary Surfaces

    Institute of Scientific and Technical Information of China (English)

    Fu-Li Wu; Chun-Hui Mei; Jiao-Ying Shi

    2004-01-01

    A direct texture synthesis method on arbitrary surfaces is proposed in this paper. The idea is to recursively map triangles on surface to texture space until the surface is completely mapped. First, the surface is simplified and a tangential vector field is created over the simplified mesh. Then, mapping process searches for the most optimal texture coordinates in texture sample for each triangle, and the textures of neighboring triangles are blended on the mesh. All synthesized texture triangles are compressed to an atlas. Finally, the simplified mesh is subdivided to approach the initial surface. The algorithm has several advantages over former methods:it synthesizes texture on surface without local parameterization; it does not need partitioning surface to patches;and it does not need a particular texture sample. The results demonstrate that the new algorithm is applicable to a wide variety of texture samples and any triangulated surfaces.

  5. Heterogeneous patterns enhancing static and dynamic texture classification

    Science.gov (United States)

    Rosa da Silva, Núbia; Martinez Bruno, Odemir

    2013-02-01

    Some mixtures, such as colloids like milk, blood, and gelatin, have homogeneous appearance when viewed with the naked eye, however, to observe them at the nanoscale is possible to understand the heterogeneity of its components. The same phenomenon can occur in pattern recognition in which it is possible to see heterogeneous patterns in texture images. However, current methods of texture analysis can not adequately describe such heterogeneous patterns. Common methods used by researchers analyse the image information in a global way, taking all its features in an integrated manner. Furthermore, multi-scale analysis verifies the patterns at different scales, but still preserving the homogeneous analysis. On the other hand various methods use textons to represent the texture, breaking texture down into its smallest unit. To tackle this problem, we propose a method to identify texture patterns not small as textons at distinct scales enhancing the separability among different types of texture. We find sub patterns of texture according to the scale and then group similar patterns for a more refined analysis. Tests were performed in four static texture databases and one dynamical one. Results show that our method provide better classification rate compared with conventional approaches both in static and in dynamic texture.

  6. Friction reduction using discrete surface textures: principle and design

    Science.gov (United States)

    Hsu, Stephen M.; Jing, Yang; Hua, Diann; Zhang, Huan

    2014-08-01

    There have been many reports on the use of dimples, grooves, and other surface textures to control friction in sliding interfaces. The effectiveness of surface textures in friction reduction has been demonstrated in conformal contacts under high speed low load applications such as mechanical seals and automotive water pump seals, etc., resulting in reduced friction and longer durability. For sliding components with higher contact pressures or lower speeds, conflicting results were reported. Reasons for the inconsistency may be due to the differences in texture fabrication techniques, lack of dimple size and shape uniformity, and different tester used. This paper examines the basic principles on which surface textural patterns influence friction under the three principle lubrication regimes: hydrodynamic, elastohydrodynamic, and boundary lubrication regimes. Our findings suggest that each regime requires specific dimple size, shape, depth, and areal density to achieve friction reduction. Control experiments were also conducted to explore mechanisms of friction reduction. The dimple geometric shape and the dimple's orientation with respect to the sliding direction influence friction significantly. The underlying mechanisms for friction control via textures are discussed.

  7. SURFACE TEXTURE ANALYSIS FOR FUNCTIONALITY CONTROL

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Andreasen, Jan Lasson; Tosello, Guido

    This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This docume...... contains a short description of each case story, 3-D roughness parameters analysis and relation with the product’s functionality.......This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This document...

  8. Dropwise condensation on inclined textured surfaces

    CERN Document Server

    Khandekar, Sameer

    2014-01-01

    Dropwise Condensation on Textured Surfaces presents a holistic framework for understanding dropwise condensation through mathematical modeling and meaningful experiments. The book presents a review of the subject required to build up models as well as to design experiments. Emphasis is placed on the effect of physical and chemical texturing and their effect on the bulk transport phenomena. Application of the model to metal vapor condensation is of special interest. The unique behavior of liquid metals, with their low Prandtl number and high surface tension, is also discussed. The model predicts instantaneous drop size distribution for a given level of substrate subcooling and derives local as well as spatio-temporally averaged heat transfer rates and wall shear stress.

  9. Wetting transitions on textured hydrophilic surfaces

    Science.gov (United States)

    Ishino, C.; Okumura, K.

    2008-04-01

    We consider the quasi-static energy of a drop on a textured hydrophilic surface, with taking the contact angle hysteresis (CAH) into account. We demonstrate how energy varies as the contact state changes from the Cassie state (in which air is trapped at the drop bottom) to the Wenzel state (in which liquid fills the texture at the drop bottom) assuming that the latter state nucleates from the center of the drop bottom. When the textured substrate is hydrophilic enough to allow spontaneous penetration of liquid film of the texture thickness, the present theory asserts that the drop develops into an experimentally observed state in which a drop looks like an egg fried without flipped over (sunny-side up) with a well-defined radius of “the egg yolk.” Otherwise, the final contact state of the drop becomes like a Wenzel state, but with the contact circle smaller than the original Wenzel state due to the CAH. We provide simple analytical estimations for the yolk radius of the “sunny-side-up” state and for the final radius of the contact circle of the pseudo-Wenzel state.

  10. Surface texture measurement for additive manufacturing

    Science.gov (United States)

    Triantaphyllou, Andrew; Giusca, Claudiu L.; Macaulay, Gavin D.; Roerig, Felix; Hoebel, Matthias; Leach, Richard K.; Tomita, Ben; Milne, Katherine A.

    2015-06-01

    The surface texture of additively manufactured metallic surfaces made by powder bed methods is affected by a number of factors, including the powder’s particle size distribution, the effect of the heat source, the thickness of the printed layers, the angle of the surface relative to the horizontal build bed and the effect of any post processing/finishing. The aim of the research reported here is to understand the way these surfaces should be measured in order to characterise them. In published research to date, the surface texture is generally reported as an Ra value, measured across the lay. The appropriateness of this method for such surfaces is investigated here. A preliminary investigation was carried out on two additive manufacturing processes—selective laser melting (SLM) and electron beam melting (EBM)—focusing on the effect of build angle and post processing. The surfaces were measured using both tactile and optical methods and a range of profile and areal parameters were reported. Test coupons were manufactured at four angles relative to the horizontal plane of the powder bed using both SLM and EBM. The effect of lay—caused by the layered nature of the manufacturing process—was investigated, as was the required sample area for optical measurements. The surfaces were also measured before and after grit blasting.

  11. Completed Local Ternary Pattern for Rotation Invariant Texture Classification

    Directory of Open Access Journals (Sweden)

    Taha H. Rassem

    2014-01-01

    Full Text Available Despite the fact that the two texture descriptors, the completed modeling of Local Binary Pattern (CLBP and the Completed Local Binary Count (CLBC, have achieved a remarkable accuracy for invariant rotation texture classification, they inherit some Local Binary Pattern (LBP drawbacks. The LBP is sensitive to noise, and different patterns of LBP may be classified into the same class that reduces its discriminating property. Although, the Local Ternary Pattern (LTP is proposed to be more robust to noise than LBP, however, the latter’s weakness may appear with the LTP as well as with LBP. In this paper, a novel completed modeling of the Local Ternary Pattern (LTP operator is proposed to overcome both LBP drawbacks, and an associated completed Local Ternary Pattern (CLTP scheme is developed for rotation invariant texture classification. The experimental results using four different texture databases show that the proposed CLTP achieved an impressive classification accuracy as compared to the CLBP and CLBC descriptors.

  12. Self-adaptive surface texture design for friction reduction across the lubrication regimes

    Science.gov (United States)

    Hsu, Stephen M.; Jing, Yang; Zhao, Fei

    2016-03-01

    Surface texturing has been shown to reduce friction and improve durability in mechanical face seals and metal forming operations, and lightly loaded thrust bearings. However, the success has been limited to conformal contacts and low load high speed operating conditions, i.e. hydrodynamic lubrication dominated regime. Both experiments and numerical simulations have shown that textural patterns, under higher loading and/or slower speeds may increase friction and even cause the lubrication film collapse. Specific designs of surface texture pattern, as its shape, depth and density, are required for different lubrication regimes. Our own study has shown (Hsu et al 2014 J. Phys. D: Appl. Phys. 47 335307) that large/shallow dimple reduces friction in hydrodynamic lubrication regime, whereas small/deep dimple shows benefit in mixed/boundary lubrication regimes (if the textural designs can provides hydrodynamic/hydrostatic lift forces to reduce the machine loading). In considering an engine component typically experiences duty cycles that may cross various lubrication regimes, a multiscale surface texture design appears attractive. This type of mixed shape texturing combines textures designed for low load, high speed operating conditions and the textures that are designed for high load, low speed operations. In this paper, two types of multiscale surface texture designs are presented. Ball-on-three-flats (BOTF) wear tester (under high loading conditions) is used to evaluate the performance of these multiscale texture designs along with the baselines of un-textured surfaces under the same surface preparation procedures. Two texture designs with only a single shape dimples are included in the study. Results suggest that multiscale surface texture design not only further reduces friction in comparison to the textures with single shape dimples, but also shows the effectiveness across hydrodynamic regimes to the mixed lubrication regimes.

  13. Texture Pattern Generation Using Clonal Mosaic

    Institute of Scientific and Technical Information of China (English)

    How Jiann Teo; Kok Cheong Wong

    2006-01-01

    In this paper, an effective system for synthesizing animal skin patterns on arbitrary polygonal surfaces is developed. To accomplish the task, a system inspired by the Clonal Mosaic (CM) model is proposed. The CM model simulates cells' reactions on arbitrary surface. By controlling the division, mutation and repulsion of cells, a regulated spatial arrangement of cells is formed. This arrangement of cells shows appealing result, which is comparable with those natural patterns observed from animal skin. However, a typical CM simulation process incurs high computational cost, where the distances among cells across a polygonal surface are measured and the movements of cells are constrained on the surface. In this framework, an approach is proposed to transform each of the original 3D geometrical planes of the surface into its Canonical Reference Plane Structure. This structure helps to simplify a 3D computational problem into a more manageable 2D problem. Furthermore, the concept of Local Relaxation is developed to optimally enhance the relaxation process for a typical CM simulation. The performances of the proposed solution methods have been verified with extensive experimental results.

  14. Dynamic air layer on textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev

    2013-09-03

    We provide an experimental demonstration that a novel macroscopic, dynamic continuous air layer or plastron can be sustained indefinitely on textured superhydrophobic surfaces in air-supersaturated water by a natural gas influx mechanism. This type of plastron is an intermediate state between Leidenfrost vapor layers on superheated surfaces and the equilibrium Cassie-Baxter wetting state on textured superhydrophobic surfaces. We show that such a plastron can be sustained on the surface of a centimeter-sized superhydrophobic sphere immersed in heated water and variations of its dynamic behavior with air saturation of the water can be regulated by rapid changes of the water temperature. The simple experimental setup allows for quantification of the air flux into the plastron and identification of the air transport model of the plastron growth. Both the observed growth dynamics of such plastrons and millimeter-sized air bubbles seeded on the hydrophilic surface under identical air-supersaturated solution conditions are consistent with the predictions of a well-mixed gas transport model. © 2013 American Chemical Society.

  15. Dynamic air layer on textured superhydrophobic surfaces.

    Science.gov (United States)

    Vakarelski, Ivan U; Chan, Derek Y C; Marston, Jeremy O; Thoroddsen, Sigurdur T

    2013-09-03

    We provide an experimental demonstration that a novel macroscopic, dynamic continuous air layer or plastron can be sustained indefinitely on textured superhydrophobic surfaces in air-supersaturated water by a natural gas influx mechanism. This type of plastron is an intermediate state between Leidenfrost vapor layers on superheated surfaces and the equilibrium Cassie-Baxter wetting state on textured superhydrophobic surfaces. We show that such a plastron can be sustained on the surface of a centimeter-sized superhydrophobic sphere immersed in heated water and variations of its dynamic behavior with air saturation of the water can be regulated by rapid changes of the water temperature. The simple experimental setup allows for quantification of the air flux into the plastron and identification of the air transport model of the plastron growth. Both the observed growth dynamics of such plastrons and millimeter-sized air bubbles seeded on the hydrophilic surface under identical air-supersaturated solution conditions are consistent with the predictions of a well-mixed gas transport model.

  16. Contact angle hysteresis on textured surfaces with nanowire clusters.

    Science.gov (United States)

    Liao, Ying-Chih; Chiang, Cheng-Kun; Lu, Yen-Wen

    2013-04-01

    Nanowire arrays with various agglomeration patterns were synthesized by adjusting the solvent evaporation rates. Nanowires with 200 nm diameter and 2-25 microm in length were fabricated from an anodic aluminum oxide (AAO) porous template. Various drying treatments were applied to develop nanostructured surfaces with topological differences. Due to surface tension forces, copper nanowires after thermal and evaporative drying treatments agglomerated into clusters, while supercritical drying technique provided excellent bundled-free and vertically-standing nanowire arrays. Although all dried surfaces exhibited hydrophobic nature, the contact angle hysteresis, or the difference between advancing and receding angles, was found to be larger on those surfaces with bundled nanowire clusters. To explain the difference, the wetted solid fraction on each surface was calculated using the Cassie-Baxter model to show that the hysteresis was contributed by liquid/solid contact area on the textured surfaces.

  17. Touching Textured Surfaces: Cells in Somatosensory Cortex Respond Both to Finger Movement and to Surface Features

    Science.gov (United States)

    Darian-Smith, Ian; Sugitani, Michio; Heywood, John; Karita, Keishiro; Goodwin, Antony

    1982-11-01

    Single neurons in Brodmann's areas 3b and 1 of the macaque postcentral gyrus discharge when the monkey rubs the contralateral finger pads across a textured surface. Both the finger movement and the spatial pattern of the surface determine this discharge in each cell. The spatial features of the surface are represented unambiguously only in the responses of populations of these neurons, and not in the responses of the constituent cells.

  18. Evaluation of long bone surface textures as ontogenetic indicators in centrosaurine ceratopsids.

    Science.gov (United States)

    Tumarkin-Deratzian, Allison R

    2009-09-01

    The search for criteria for aging non-mammalian fossil vertebrates has preoccupied paleobiologists in recent years. Previous studies of the long bones of pterosaurs and modern and subfossil birds as well as of cranial material of centrosaurine ceratopsid dinosaurs have documented variations in surface textures that seem to be ontogenetically related. In this study, long bones from the centrosaurine ceratopsid genera Centrosaurus, Einiosaurus, and Pachyrhinosaurus are examined to test the hypothesis that changes in bone surface textures and reduction of surface porosity could be correlated with size (and presumably age) classes, as has been previously documented in pterosaurs and birds. The data set includes 141 bones representing all six long bone elements, collected from monodominant centrosaurine bone beds. Bone surface patterns are documented by macroscopic visual examination, and a sequence of five texture classes ordered by decreasing surface porosity is described based on the common distributions of these patterns. Calculations of Spearman's rank correlation coefficients reveal significant correlations between texture class and size. The smallest bones are invariably associated with porous midshaft textures that grade to fibrous and long-grained patterns proximally and distally [Texture Class (TC) 1]. Post-hoc analysis after Kruskal-Wallis ANOVA on ranks confirms that the mean size of TC1 bones is, in most cases, significantly different than the mean size of bones in other texture classes. Results of this study suggest the presence of an ontogenetic surface textural signal in centrosaurine long bones; however, comparison of texture classes with size-independent maturity criteria is needed to clarify further the potential ontogenetic significance of higher texture classes.

  19. Perceived beauty of random texture patterns: A preference for complexity.

    Science.gov (United States)

    Friedenberg, Jay; Liby, Bruce

    2016-07-01

    We report two experiments on the perceived aesthetic quality of random density texture patterns. In each experiment a square grid was filled with a progressively larger number of elements. Grid size in Experiment 1 was 10×10 with elements added to create a variety of textures ranging from 10%-100% fill levels. Participants rated the beauty of the patterns. Average judgments across all observers showed an inverted U-shaped function that peaked near middle densities. In Experiment 2 grid size was increased to 15×15 to see if observers preferred patterns with a fixed density or a fixed number of elements. The results of the second experiment were nearly identical to that of the first showing a preference for density over fixed element number. Ratings in both studies correlated positively with a GIF compression metric of complexity and with edge length. Within the range of stimuli used, observers judge more complex patterns to be more beautiful.

  20. The Application of Marker Based Segmentation for Surface Texture Characterization

    Directory of Open Access Journals (Sweden)

    Che Pin Nuraini binti

    2016-01-01

    Full Text Available Structured surfaces have been increasingly used in industry for a variety of applications, including improving the tribological properties of the surfaces. Surface metrology plays an important role in this discipline since with the help of surface metrology technology, surface texture can be measured, visualize and quantified. Traditional surface texture parameters, such as roughness and waviness, cannot be related to the function for structured surfaces due to the less statistical description and little information. Therefore, a new approaches based on characterizing the structured surface is introduces where this paper focus on type of edges grain surface. To identify features, it is a must to detect the location of the edges and segmented the features based on the detected edges. Hence characterization of surface texture segmentation based on the edges detection is developing using Marker Based segmentation and it is prove that this method is possible to be used in order to characterize the structured surface.

  1. Use of Textured Surfaces to Mitigate Sliding Friction and Wear of Lubricated and Non-Lubricated Contacts

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL

    2012-03-01

    If properly employed, the placement of three-dimensional feature patterns, also referred to as textures, on relatively-moving, load-bearing surfaces can be beneficial to their friction and wear characteristics. For example, geometric patterns can function as lubricant supply channels or depressions in which to trap debris. They can also alter lubricant flow in a manner that produces thicker load-bearing films locally. Considering the area occupied by solid areas and spaces, textures also change the load distribution on surfaces. At least ten different attributes of textures can be specified, and their combinations offer wide latitude in surface engineering. By employing directional machining and grinding procedures, texturing has been used on bearings and seals for well over a half century, and the size scales of texturing vary widely. This report summarizes past work on the texturing of load-bearing surfaces, including past research on laser surface dimpling of ceramics done at ORNL. Textured surfaces generally show most pronounced effects when they are used in conformal or nearly conformal contacts, like that in face seals. Combining textures with other forms of surface modification and lubrication methods can offer additional benefits in surface engineering for tribology. As the literature and past work at ORNL shows, texturing does not always provide benefits. Rather, the selected pattern and arrangement of features must be matched to characteristics of the proposed application, bearing materials, and lubricants.

  2. Classification of interstitial lung disease patterns with topological texture features

    CERN Document Server

    Huber, Markus B; Leinsinger, Gerda; Ray, Lawrence A; Wismüller, Axel; 10.1117/12.844318

    2010-01-01

    Topological texture features were compared in their ability to classify morphological patterns known as 'honeycombing' that are considered indicative for the presence of fibrotic interstitial lung diseases in high-resolution computed tomography (HRCT) images. For 14 patients with known occurrence of honey-combing, a stack of 70 axial, lung kernel reconstructed images were acquired from HRCT chest exams. A set of 241 regions of interest of both healthy and pathological (89) lung tissue were identified by an experienced radiologist. Texture features were extracted using six properties calculated from gray-level co-occurrence matrices (GLCM), Minkowski Dimensions (MDs), and three Minkowski Functionals (MFs, e.g. MF.euler). A k-nearest-neighbor (k-NN) classifier and a Multilayer Radial Basis Functions Network (RBFN) were optimized in a 10-fold cross-validation for each texture vector, and the classification accuracy was calculated on independent test sets as a quantitative measure of automated tissue characteriza...

  3. Tribological performance analysis of textured steel surfaces under lubricating conditions

    Science.gov (United States)

    Singh, R. C.; Pandey, R. K.; Rooplal; Ranganath, M. S.; Maji, S.

    2016-09-01

    The tribological analysis of the lubricated conformal contacts formed between the smooth/textured surfaces of steel discs and smooth surface of steel pins under sliding conditions have been considered. Roles of dimples’ pitch of textured surfaces have been investigated experimentally to understand the variations of coefficient of friction and wear at the tribo-contacts under fully flooded lubricated conditions. Substantial reductions in coefficient of friction and wear at the tribo-interfaces have been observed in presence of textures on the rotating discs for both fully flooded and starved conditions in comparison to the corresponding lubricating conditions of the interfaces formed between the smooth surfaces of disc and pin. In presence of surface texture, the coefficient of friction reduces considerable at elevated sliding speeds (>2 m/s) and unit loads (>0.5 MPa) for the set of operating parameters considered in the analysis.

  4. DNS of turbulent flows over superhydrophobic surfaces: effect of texture randomness

    Science.gov (United States)

    Seo, Jongmin; Mani, Ali

    2016-11-01

    Superhydrophobic surfaces (SHS) are non-wetting surfaces consisting of hydrophobic material and nano/micro-scale structures. When in contact with overlaying liquid flows, such structures can entrap gas and therefore suppress the direct contact between water and solid, reducing skin friction. SHS patterns can utilize a wide range of geometries including posts, ridges, and etched holes, either in a pre-specified arrangement or randomly distributed. In this work we investigate how the randomness of such patterns affect the drag reduction and interfacial robustness when these surfaces are under turbulent flows. We perform direct numerical simulations of turbulent flows over randomly patterned slip surface on a wide range of texture parameters. We present slip lengths of randomly distributed SHS for texture widths w+ = 4 - 26, and solid fractions from 11% to 25%. For fixed gas fraction and texture size, the slip lengths of randomly distributed textures are less than those of aligned textures. We show that the geometric randomness of texture distribution weakens the interfacial robustness of the gas pocket. Support from Office of Naval Research (ONR) under Grant #3002451214 is gratefully acknowledged.

  5. Study on the fabrication of titanium surface texture by nanosecond laser and its wettability

    Directory of Open Access Journals (Sweden)

    Chengjuan YANG

    2016-08-01

    Full Text Available Laser processing technology can produce various types of surface textures on material. In order to investigate the effect of surface texture type processed by laser on the wettability, line, grid and spot patterns are fabricated on titanium surface based on nanosecond laser processing technology. Then surface morphology, water contact angle, roughness and chemical composition of the processed titanium surface are analyzed by scanning electron microscope, contact angle measuring device, surface analyzer and X-ray photoelectron spectroscopy, respectively. It is found that the roughness of titanium surfaces processed by nanosecond laser increases significantly compared with that of the unprocessed titanium surface, while the surface contact angles of the processed titanium surfaces are all less than 90°. As time goes on, the chemical composition variation of ablated titanium surface results in the change of material surface free energy, which leads to a general increase of the surface contact angle. Finally, the surface contact angle is almost unchanged once the chemical composition of titanium surface reaches steady state. For each type of surface texture, surface contact angle increases as the roughness rises. The surface contact angles of processed titanium surfaces with line, grid and spot patterns can be 157.2°, 153.1° and 134.6°, which verifies the possibility of wettability change of titanium from hydrophilicity to hydrophobicity.

  6. Applications of pattern recognition in aluminum alloy texture characterization

    Science.gov (United States)

    Liu, Guizhong; Rehbein, D. K.; Foley, James C.; Thompson, R. B.

    2000-05-01

    This paper presents a methodology to extract texture information in Aluminum alloys using pattern recognition algorithm. The orientation of the samples can be obtained by the orientation Image Microscope (OIM) technique. The ISO DATA pattern recognition algorithm is implemented to classify the OIM data into different clusters. Based on the classification results, the probability density function (pdf) is estimated. Then, the pdf is expanded as a series of Legendre functions with coefficients, i.e., the orientation distribution coefficients (ODC) as texture parameters. Three of these ODC's are of special interests, namely W400, W420, and W440. This paper includes results from ultrasonic NDE and this novel algorithm.—Ames Laboratory is operated for U.S. Department of Energy by Iowa State University under Contract W-7405-ENG-82. This work was supported by the Office of Basic Energy Sciences as a part of the Center of Excellence of the Synthesis and Processing of Advanced Materials.

  7. Classifying Similarity and Defect Fabric Textures based on GLCM and Binary Pattern Schemes

    Directory of Open Access Journals (Sweden)

    R. Obula Konda Reddy

    2013-11-01

    Full Text Available Textures are one of the basic features in visual searching,computational vision and also a general property of any surface having ambiguity. This paper presents a texture classification system which has high tolerance against illumination variation. A Gray Level Co-occurrence Matrix (GLCM and binary pattern based automated similarity identification and defect detection model is presented. Different features are calculated from both GLCM and binary patterns (LBP, LLBP, and SLBP. Then a new rotation-invariant, scale invariant steerable decomposition filter is applied to filter the four orientation sub bands of the image. The experimental results are evaluated and a comparative analysis has been performed for the four different feature types. Finally the texture is classified by different classifiers (PNN, K-NN and SVM and the classification performance of each classifier is compared. The experimental results have shown that the proposed method produces more accuracy and better classification accuracy over other methods.

  8. Critical heat flux maxima during boiling crisis on textured surfaces

    Science.gov (United States)

    Dhillon, Navdeep Singh; Buongiorno, Jacopo; Varanasi, Kripa K.

    2015-01-01

    Enhancing the critical heat flux (CHF) of industrial boilers by surface texturing can lead to substantial energy savings and global reduction in greenhouse gas emissions, but fundamentally this phenomenon is not well understood. Prior studies on boiling crisis indicate that CHF monotonically increases with increasing texture density. Here we report on the existence of maxima in CHF enhancement at intermediate texture density using measurements on parametrically designed plain and nano-textured micropillar surfaces. Using high-speed optical and infrared imaging, we study the dynamics of dry spot heating and rewetting phenomena and reveal that the dry spot heating timescale is of the same order as that of the gravity and liquid imbibition-induced dry spot rewetting timescale. Based on these insights, we develop a coupled thermal-hydraulic model that relates CHF enhancement to rewetting of a hot dry spot on the boiling surface, thereby revealing the mechanism governing the hitherto unknown CHF enhancement maxima. PMID:26346098

  9. Drops bouncing off macro-textured superhydrophobic surfaces

    CERN Document Server

    Moqaddam, Ali Mazloomi; Karlin, Ilya

    2016-01-01

    Recent experiments with droplets impacting a macro-textured superhydrophobic surfaces revealed new regimes of bouncing with a remarkable reduction of the contact time. We present here a comprehensive numerical study that reveals the physics behind these new bouncing regimes and quantify the role played by various external and internal forces that effect the dynamics of a drop impacting a complex surface. For the first time, three-dimensional simulations involving macro-textured surfaces are performed. Aside from demonstrating that simulations reproduce experiments in a quantitative manner, the study is focused on analyzing the flow situations beyond current experiments. We show that the experimentally observed reduction of contact time extends to higher Weber numbers, and analyze the role played by the texture density. Moreover, we report a non-linear behavior of the contact time with the increase of the Weber number for application relevant imperfectly coated textures, and also study the impact on tilted sur...

  10. Classification of interstitial lung disease patterns with topological texture features

    Science.gov (United States)

    Huber, Markus B.; Nagarajan, Mahesh; Leinsinger, Gerda; Ray, Lawrence A.; Wismüller, Axel

    2010-03-01

    Topological texture features were compared in their ability to classify morphological patterns known as 'honeycombing' that are considered indicative for the presence of fibrotic interstitial lung diseases in high-resolution computed tomography (HRCT) images. For 14 patients with known occurrence of honey-combing, a stack of 70 axial, lung kernel reconstructed images were acquired from HRCT chest exams. A set of 241 regions of interest of both healthy and pathological (89) lung tissue were identified by an experienced radiologist. Texture features were extracted using six properties calculated from gray-level co-occurrence matrices (GLCM), Minkowski Dimensions (MDs), and three Minkowski Functionals (MFs, e.g. MF.euler). A k-nearest-neighbor (k-NN) classifier and a Multilayer Radial Basis Functions Network (RBFN) were optimized in a 10-fold cross-validation for each texture vector, and the classification accuracy was calculated on independent test sets as a quantitative measure of automated tissue characterization. A Wilcoxon signed-rank test was used to compare two accuracy distributions and the significance thresholds were adjusted for multiple comparisons by the Bonferroni correction. The best classification results were obtained by the MF features, which performed significantly better than all the standard GLCM and MD features (p interstitial lung diseases when compared to standard texture analysis methods.

  11. Characterisation of group behaviour surface texturing with multi-layers fitting method

    Science.gov (United States)

    Kang, Zhengyang; Fu, Yonghong; Ji, Jinghu; Wang, Hao

    2016-07-01

    Surface texturing was widely applied in improving the tribological properties of mechanical components, but study of measurement of this technology was still insufficient. This study proposed the multi-layers fitting (MLF) method to characterise the dimples array texture surface. Based on the synergistic effect among the dimples, the 3D morphology of texture surface was rebuilt by 2D stylus profiler in the MLF method. The feasible regions of texture patterns and sensitive parameters were confirmed by non-linear programming, and the processing software of MLF method was developed based on the Matlab®. The characterisation parameters system of dimples was defined mathematically, and the accuracy of MLF method was investigated by comparison experiment. The surface texture specimens were made by laser surface texturing technology, in which high consistency of dimples' size and distribution was achieved. Then, 2D profiles of different dimples were captured by employing Hommel-T1000 stylus profiler, and the data were further processed by MLF software to rebuild 3D morphology of single dimple. The experiment results indicated that the MLF characterisation results were similar to those of Wyko T1100, the white light interference microscope. It was also found that the stability of MLF characterisation results highly depended on the number of captured cross-sections.

  12. Orthogonal combination of local binary patterns for dynamic texture recognition

    Science.gov (United States)

    Chen, Yin; Guo, Xuejun; Klein, Dominik

    2015-12-01

    Dynamic texture (DT) is an extension of texture to the temporal domain. Recognizing DTs has received increasing attention. Volume local binary pattern (VLBP) is the most widely used descriptor for DTs. However, it is time consuming to recognize DTs using VLBP due to the large scale of data and the high dimensionality of the descriptor itself. In this paper, we propose a new operator called orthogonal combination of VLBP (OC-VLBP) for DT recognition. The original VLBP is decomposed both longitudinally and latitudinally, and then combined to constitute the OC-VLBP operator, so that the dimensionality of the original VLBP descriptor is lowered. The experimental results show that the proposed operator significantly reduces the computational costs of recognizing DTs without much loss in recognizing accuracy.

  13. Algorithms and software for areal surface texture function parameters

    Science.gov (United States)

    Smith, I. M.; Harris, P. M.; Todhunter, L. D.; Giusca, C.; Jiang, X.; Scott, P.; Leach, R. K.

    2017-10-01

    Software for the evaluation of areal surface texture function parameters is described. Definitions of the parameters, expressed in terms of the inverse areal material ratio function, are provided along with details of the numerical algorithms employed in the software to implement calculations to evaluate approximations to the parameters according to those definitions. Results obtained using the software to process a number of data sets representing different surfaces are compared with those returned by proprietary software for surface texture measurement. Differences in the results, arising from different choices being made when implementing the steps in the parameter evaluation process, are discussed.

  14. A scattering model for surface-textured thin films

    NARCIS (Netherlands)

    Jäger, K.; Zeman, M.

    2009-01-01

    We present a mathematical model that relates the surface morphology of randomly surface-textured thin films with the intensity distribution of scattered light. The model is based on the first order Born approximation [see e.g., M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge University

  15. A scattering model for surface-textured thin films

    NARCIS (Netherlands)

    Jäger, K.; Zeman, M.

    2009-01-01

    We present a mathematical model that relates the surface morphology of randomly surface-textured thin films with the intensity distribution of scattered light. The model is based on the first order Born approximation [see e.g., M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge University

  16. Texture Classification in Lung CT Using Local Binary Patterns

    DEFF Research Database (Denmark)

    Sørensen, Lauge Emil Borch Laurs; Shaker, Saher B.; de Bruijne, Marleen

    2008-01-01

    Abstract In this paper we propose to use local binary patterns (LBP) as features in a classification framework for classifying different texture patterns in lung computed tomography. Image intensity is included by means of the joint LBP and intensity histogram, and classification is performed using...... the k nearest neighbor classifier with histogram similarity as distance measure. The proposed method is evaluated on a set of 168 regions of interest comprising normal tissue and different emphysema patterns, and compared to a filter bank based on Gaussian derivatives. The joint LBP and intensity...... histogram, achieving a classification accuracy of 95.2%, shows superior performance to using the common approach of taking moments of the filter response histograms as features, and slightly better performance than using the full filter response histograms instead. Classification results are better than...

  17. Correlation between gloss reflectance and surface texture in photographic paper.

    Science.gov (United States)

    Vessot, Kevin; Messier, Paul; Hyde, Joyce M; Brown, Christopher A

    2015-01-01

    Surface textures of a large collection of photographic papers dating from 1896 to the present were measured using a laser scanning confocal microscope (LSCM) with four different objective lenses. Roughness characterization parameters were calculated from the texture measurements and were compared with gloss measurements. Characterization by the area-scale fractal dimension (Das) and the area-scale fractal complexity (Asfc) provided the strongest correlations between gloss reflectance and surface texture. The measurements with the 5× and 10× objectives, which contained many large-scale, spiky measurement artifacts that distorted the measurement, resulted in the strongest correlations (R(2)  > 0.8) compared to the 20× and 50× (R(2)  < 0.5). The presence of spiky artifacts in the measurements, which increases when the magnification of the objective lens is decreased, appears to amplify surface features in such a way to improve the correlations.

  18. Multi-texture local ternary pattern for face recognition

    Science.gov (United States)

    Essa, Almabrok; Asari, Vijayan

    2017-05-01

    In imagery and pattern analysis domain a variety of descriptors have been proposed and employed for different computer vision applications like face detection and recognition. Many of them are affected under different conditions during the image acquisition process such as variations in illumination and presence of noise, because they totally rely on the image intensity values to encode the image information. To overcome these problems, a novel technique named Multi-Texture Local Ternary Pattern (MTLTP) is proposed in this paper. MTLTP combines the edges and corners based on the local ternary pattern strategy to extract the local texture features of the input image. Then returns a spatial histogram feature vector which is the descriptor for each image that we use to recognize a human being. Experimental results using a k-nearest neighbors classifier (k-NN) on two publicly available datasets justify our algorithm for efficient face recognition in the presence of extreme variations of illumination/lighting environments and slight variation of pose conditions.

  19. Investigation of the tribology behaviour of the graphene nanosheets as oil additives on textured alloy cast iron surface

    Science.gov (United States)

    Zheng, Dan; Cai, Zhen-bing; Shen, Ming-xue; Li, Zheng-yang; Zhu, Min-hao

    2016-11-01

    Tribological properties of graphene nanosheets (GNS) as lubricating oil additives on textured surfaces were investigated using a UMT-2 tribotester. The lubricating fluids keeping a constant temperature of 100 °C were applied to a GCr15 steel ball and an RTCr2 alloy cast iron plate with various texture designs (original surface, dimple density of 22.1%, 19.6% and 44.2%). The oil with GNS adding showed good tribological properties (wear reduced 50%), especially on the textured surfaces (the reduction in wear was high at over 90%). A combined effect between GNS additives and laser surface texturing (LST) was revealed, which is not a simple superposition of the two factors mentioned. A mechanism is proposed to explain for these results -the graphene layers sheared at the sliding contact interfaces, and form a protective film, which is closely related with the GNS structures and surface texture patterns.

  20. A Study on the Surface Oxidation Behavior of Cube-textured Nickel Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Ji Hyun; Kim, Byeong Joo; Kim, Jae Geun; Kim, Ho Jin; Hong, Gye Won; Lee, Hee Gyoun [Korea Polytechnic University, Siheung (Korea, Republic of); Yoo, Jai Moo [Korea Instititue of Machinery and Matrials, Changwon (Korea, Republic of); Pradeep, Halder [College of Namoscale Science and Engineering, University at Albany, State University of NewYork, Albany (United States)

    2005-10-15

    We investigated the surface oxidation behavior of cube-textured polycrystalline nickel at various oxidation conditions. Cube-textured NiO film was formed on a cube-textured polycrystalline nickel regardless of oxidation conditions but different growth behavior of NiO crystals was observed depending on the oxidation conditions. The introduction of water vapor into O{sub 2} did not affect the texture evolution, but rough and porous microstructure was developed. Microstructure of NiO film tends to be denser as the oxygen partial pressure increases. It is interesting that peak of theta - two theta diffraction pattern started to get stronger in air atmosphere and plane became the major texture in the substrate oxidized in high purity argon gas. Small amount of high index crystallographic plane NiO peak crystal was observed when N{sub 2}Owas used as an oxidant while only plane crystal was formed in dry O{sub 2} atmosphere. Flat and smooth surface was changed into rough faceted one when ramping rate to oxidation temperature was faster. The grain size of NiO was decreased when the oxygen partial pressure was low. It was also observed that the modification of nickel surface suppressed the development of texture.

  1. Surface texturing of superconductors by controlled oxygen pressure

    Science.gov (United States)

    Chen, N.; Goretta, K.C.; Dorris, S.E.

    1999-01-05

    A method of manufacture of a textured layer of a high temperature superconductor on a substrate is disclosed. The method involves providing an untextured high temperature superconductor material having a characteristic ambient pressure peritectic melting point, heating the superconductor to a temperature below the peritectic temperature, establishing a reduced pO{sub 2} atmosphere below ambient pressure causing reduction of the peritectic melting point to a reduced temperature which causes melting from an exposed surface of the superconductor and raising pressure of the reduced pO{sub 2} atmosphere to cause solidification of the molten superconductor in a textured surface layer. 8 figs.

  2. Nanoparticle-textured surfaces from spin coating.

    Science.gov (United States)

    Weiss, R A; Zhai, X; Dobrynin, A V

    2008-05-20

    Rough surfaces composed of discrete but relatively uniform nanoparticles were prepared from a lightly sulfonated polystyrene ionomer by spin coating from tetrahydrofuran (THF) or a THF/methanol mixture onto a silica surface. The particle morphology is consistent with the spinodal decomposition of the film surface occurring during spin coating. The particles are well wetted to the silica, and if heated for a long time above the ionomer's glass-transition temperature, the particles flow and coalesce into a smooth, homogeneous film.

  3. Drops bouncing off macro-textured superhydrophobic surfaces

    Science.gov (United States)

    Mazloomi Moqaddam, Ali; Chikatamarla, Shyam S.; Karlin, Iliya V.

    2017-08-01

    Recent experiments with droplets impacting a macro-textured superhydrophobic surfaces revealed new regimes of bouncing with a remarkable reduction of the contact time. We present here a comprehensive numerical study that reveals the physics behind these new bouncing regimes and quantify the role played by various external and internal forces that effect the dynamics of a drop impacting a complex surface. For the first time, three-dimensional simulations involving macro-textured surfaces are performed. Aside from demonstrating that simulations reproduce experiments in a quantitative manner, the study is focused on analyzing the flow situations beyond current experiments. We show that the experimentally observed reduction of contact time extends to higher Weber numbers, and analyze the role played by the texture density. Moreover, we report a non-linear behavior of the contact time with the increase of the Weber number for application relevant imperfectly coated textures, and also study the impact on tilted surfaces in a wide range of Weber numbers. Finally, we present novel energy analysis techniques that elaborate and quantify the interplay between the kinetic and surface energy, and the role played by the dissipation for various Weber numbers.

  4. Neuronal Alignment On Asymmetric Textured Surfaces

    CERN Document Server

    Beighley, Ross; Sekeroglu, Koray; Atherton, Timothy; Demirel, Melik C; Staii, Cristian

    2013-01-01

    Axonal growth and the formation of synaptic connections are key steps in the development of the nervous system. Here we present experimental and theoretical results on axonal growth and interconnectivity in order to elucidate some of the basic rules that neuronal cells use for functional connections with one another. We demonstrate that a unidirectional nanotextured surface can bias axonal growth. We perform a systematic investigation of neuronal processes on asymmetric surfaces and quantify the role that biomechanical surface cues play in neuronal growth. These results represent an important step towards engineering directed axonal growth for neuro-regeneration studies.

  5. Control and characterization of textured, hydrophobic ionomer surfaces

    Science.gov (United States)

    Wang, Xueyuan

    Polymer thin films are of increasing interest in many industrial and technological applications. Superhydrophobic, self-cleaning surfaces have attracted a lot of attention for their application in self-cleaning, anti-sticking coatings, stain resistance, or anti-contamination surfaces in diverse technologies, including medical, transportation, textiles, electronics and paints. This thesis focuses on the preparation of nanometer to micrometer-size particle textured surfaces which are desirable for super water repellency. Textured surfaces consisting of nanometer to micrometer-sized lightly sulfonated polystyrene ionomer (SPS) particles were prepared by rapid evaporation of the solvent from a dilute polymer solution cast onto silica. The effect of the solvent used to spin coat the film, the molecular weight of the ionomer, and the rate of solvent evaporation were investigated. The nano-particle or micron-particle textured ionomer surfaces were prepared by either spin coating or solution casting ionomer solutions at controlled evaporation rates. The surface morphologies were consistent with a spinodal decomposition mechanism where the surface first existed as a percolated-like structure and then ripened into droplets if molecular mobility was retained for sufficient time. The SPS particles or particle aggregates were robust and resisted deformation even after annealing at 120°C for one week. The water contact angles on as-prepared surfaces were relatively low, ~ 90° since the polar groups in ionomer reduce the surface hydrophobicity. After chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltrichlorosilane, the surface contact angles increased to ~ 109° on smooth surfaces and ~140° on the textured surfaces. Water droplets stuck to these surfaces even when tilted 90 degrees. Superhydrophobic surfaces were prepared by spraying coating ionomer solutions and Chemical Vapor Deposition (CVD) of 1H,1H,2H,2H-perfluorooctyltrichlorosilane onto textured surfaces. The

  6. Observation of water condensate on hydrophobic micro textured surfaces

    Science.gov (United States)

    Kim, Ki Wook; Do, Sang Cheol; Ko, Jong Soo; Jeong, Ji Hwan

    2013-07-01

    We visually observed that a dropwise condensation occurred initially and later changed into a filmwise condensation on hydrophobic textured surface at atmosphere pressure condition. It was observed that the condensate nucleated on the pillar side walls of the micro structure and the bottom wall adhered to the walls and would not be lifted to form a spherical water droplet using environmental scanning electron microscope.

  7. Texture Gradient Effectiveness in the Perception of Surface Slant

    Science.gov (United States)

    Rosinski, Richard R.; Levine, Nancy Parker

    1976-01-01

    To assess the development of monocular slant perception as well as the relative effectiveness of different sources of information, 90 children in first, third, and fifth grades and 30 college adults were asked to make judgments of surface slant on the basis of monocular texture gradient information. (Author/JH)

  8. Static Performance of Surface Textured Magnetorheological Fluid Journal Bearings

    Directory of Open Access Journals (Sweden)

    D.A. Bompos

    2015-09-01

    Full Text Available Previous studies of journal bearings with artificial texturing on the bearing surface show potential benefits in certain cases. These benefits are usually focused on a specific operating area of the bearing, whereas under certain operating conditions the performance of the bearing is deteriorating due to the surface texturing. Gaining control over the viscosity of the lubricant may become a useful tool in order to take advantage of the surface texturing in a wider range of loads and journal velocities. One way to achieve this control is the use of magnetorheological fluid journal bearings. Magnetorheological fluids are solutions of iron based paramagnetic particles in conventional lubricant. Under the influence of an external magnetic field, these particles form chains, they hinder the flow of the lubricant and they ultimately alter its apparent viscosity. In this work the two techniques are combined in order to optimize the behaviour of the journal bearing in as much a variety of operating conditions as possible. Different shapes applied on the surface texturing will be examined.

  9. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces.

    Science.gov (United States)

    Vakarelski, Ivan U; Patankar, Neelesh A; Marston, Jeremy O; Chan, Derek Y C; Thoroddsen, Sigurdur T

    2012-09-13

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling--by heat transfer--the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating.

  10. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev

    2012-09-12

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

  11. Conveying the 3D Shape of Transparent Surfaces Via Texture

    Science.gov (United States)

    Interrante, Victoria; Fuchs, Henry; Pizer, Stephen

    1997-01-01

    Transparency can be a useful device for depicting multiple overlapping surfaces in a single image. The challenge is to render the transparent surfaces in such a way that their three-dimensional shape can be readily understood and their depth distance from underlying structures clearly perceived. This paper describes our investigations into the use of sparsely-distributed discrete, opaque texture as an 'artistic device' for more explicitly indicating the relative depth of a transparent surface and for communicating the essential features of its 3D shape in an intuitively meaningful and minimally occluding way. The driving application for this work is the visualization of layered surfaces in radiation therapy treatment planning data, and the technique is illustrated on transparent isointensity surfaces of radiation dose. We describe the perceptual motivation and artistic inspiration for defining a stroke texture that is locally oriented in the direction of greatest normal curvature (and in which individual strokes are of a length proportional to the magnitude of the curvature in the direction they indicate), and discuss several alternative methods for applying this texture to isointensity surfaces defined in a volume. We propose an experimental paradigm for objectively measuring observers' ability to judge the shape and depth of a layered transparent surface, in the course of a task relevant to the needs of radiotherapy treatment planning, and use this paradigm to evaluate the practical effectiveness of our approach through a controlled observer experiment based on images generated from actual clinical data.

  12. Texture analysis of cervical cell nuclei by segmentation of chromatin patterns

    NARCIS (Netherlands)

    Smeulders, A.W.M.; Leyte-Veldstra, L.; Ploem, J.S.; Cornelisse, C.JJ.

    1979-01-01

    Texture parameters of the nuclear chromatin pattern can contribute to the automated classification of specimens on the basis of single cell analysis in cervical cytology. Current texture parameters are abstract and therefore hamper understanding. In this paper texture parameters are described that c

  13. Nanosecond laser textured superhydrophobic metallic surfaces and their chemical sensing applications

    Science.gov (United States)

    Ta, Duong V.; Dunn, Andrew; Wasley, Thomas J.; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Connaughton, Colm; Shephard, Jonathan D.

    2015-12-01

    This work demonstrates superhydrophobic behavior on nanosecond laser patterned copper and brass surfaces. Compared with ultrafast laser systems previously used for such texturing, infrared nanosecond fiber lasers offer a lower cost and more robust system combined with potentially much higher processing rates. The wettability of the textured surfaces develops from hydrophilicity to superhydrophobicity over time when exposed to ambient conditions. The change in the wetting property is attributed to the partial deoxidation of oxides on the surface induced during laser texturing. Textures exhibiting steady state contact angles of up to ∼152° with contact angle hysteresis of around 3-4° have been achieved. Interestingly, the superhydrobobic surfaces have the self-cleaning ability and have potential for chemical sensing applications. The principle of these novel chemical sensors is based on the change in contact angle with the concentration of methanol in a solution. To demonstrate the principle of operation of such a sensor, it is found that the contact angle of methanol solution on the superhydrophobic surfaces exponentially decays with increasing concentration. A significant reduction, of 128°, in contact angle on superhydrophobic brass is observed, which is one order of magnitude greater than that for the untreated surface (12°), when percent composition of methanol reaches to 28%.

  14. Interface shear strength of textured geomembrane with nonwoven geotextile and change pattern of surface asperity%糙面土工膜与无纺土工织物界面剪切强度及表面粗糙度变化规律

    Institute of Scientific and Technical Information of China (English)

    施建勇; 李砚

    2016-01-01

    为了量化糙面土工膜表面粗糙度变化规律,研制了表面粗糙度测量仪,并进行了不同法向应力下糙面土工膜和无纺土工织物界面剪切和对应的糙面土工膜表面粗糙度试验。研究表明,糙面土工膜和无纺土工织物界面剪切强度是由糙面土工膜粗糙凸起和无纺土工织物纤维相互嵌入和拉拽作用产生的,界面的剪切峰值摩擦系数主要受到法向应力的影响,界面强度发展到残余强度,糙面土工膜粗糙凸起磨损趋于稳定,无纺土工织物纤维定向排列完成。%In order to quantitatively investigate the pattern of change of the surface asperity of textured geomembrane, a new apparatus for measuring surface asperity was developed. Interface shear tests of textured geomembrane with nonwoven geotextile under different normal stresses and corresponding tests on the surface asperity of textured geomembrane were conducted. The results show that the interface shear strength of textured geomembrane with nonwoven geotextile is caused by the embedding and pulling actions between textured points of geomembrane and geotextile fabric. The peak interface shear friction coefficient is mainly influenced by normal stress. When the interface shear strength tends to be residual strength, the damage to textured points of geomembrane tends to be stable and the fabric orientation of geotextile is fully achieved.

  15. Ion Beam Textured and Coated Surfaces Experiment (IBEX)

    Science.gov (United States)

    Mirtich, Michael J.; Rutledge, Sharon K.; Stevens, Nicholas; Olle, Raymond; Merrow, James

    1992-01-01

    Ion beam textured and commercial materials suitable for use in space power systems were flown in low Earth orbit on the Long Duration Exposure Facility (LDEF) for 5.8 years. Because of their location on LDEF (98 deg from the ram direction), the 36 materials were primarily exposed to vacuum ultraviolet radiation, thermal cycling, the vacuum of space, the micrometeoroid environment, and grazing incidence atomic oxygen. Measurements of solar absorptance and thermal emittance (pre- and post-flight) showed no changes for almost all of the materials, except for the S-13G and Kapton and coated Kapton samples. The optical property stability of ion beam textured surfaces and most other surfaces indicates that they are functionally durable to the synergistic rigors of the space environment.

  16. Temperature dependent droplet impact dynamics on flat and textured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Azar Alizadeh; Vaibhav Bahadur; Sheng Zhong; Wen Shang; Ri Li; James Ruud; Masako Yamada; Liehi Ge; Ali Dhinojwala; Manohar S Sohal (047160)

    2012-03-01

    Droplet impact dynamics determines the performance of surfaces used in many applications such as anti-icing, condensation, boiling and heat transfer. We study impact dynamics of water droplets on surfaces with chemistry/texture ranging from hydrophilic to superhydrophobic and across a temperature range spanning below freezing to near boiling conditions. Droplet retraction shows very strong temperature dependence especially for hydrophilic surfaces; it is seen that lower substrate temperatures lead to lesser retraction. Physics-based analyses show that the increased viscosity associated with lower temperatures can explain the decreased retraction. The present findings serve to guide further studies of dynamic fluid-structure interaction at various temperatures.

  17. Surface classification and detection of latent fingerprints based on 3D surface texture parameters

    Science.gov (United States)

    Gruhn, Stefan; Fischer, Robert; Vielhauer, Claus

    2012-06-01

    In the field of latent fingerprint detection in crime scene forensics the classification of surfaces has importance. A new method for the scientific analysis of image based information for forensic science was investigated in the last years. Our image acquisition based on a sensor using Chromatic White Light (CWL) with a lateral resolution up to 2 μm. The used FRT-MicroProf 200 CWL 600 measurement device is able to capture high-resolution intensity and topography images in an optical and contact-less way. In prior work, we have suggested to use 2D surface texture parameters to classify various materials, which was a novel approach in the field of criminalistic forensic using knowledge from surface appearance and a chromatic white light sensor. A meaningful and useful classification of different crime scene specific surfaces is not existent. In this work, we want to extend such considerations by the usage of fourteen 3D surface parameters, called 'Birmingham 14'. In our experiment we define these surface texture parameters and use them to classify ten different materials in this test set-up and create specific material classes. Further it is shown in first experiments, that some surface texture parameters are sensitive to separate fingerprints from carrier surfaces. So far, the use of surface roughness is mainly known within the framework of material quality control. The analysis and classification of the captured 3D-topography images from crime scenes is important for the adaptive preprocessing depending on the surface texture. The adaptive preprocessing in dependency of surface classification is necessary for precise detection because of the wide variety of surface textures. We perform a preliminary study in usage of these 3D surface texture parameters as feature for the fingerprint detection. In combination with a reference sample we show that surface texture parameters can be an indication for a fingerprint and can be a feature in latent fingerprint detection.

  18. Texturing of UHMWPE surface via NIL for low friction and wear properties

    Energy Technology Data Exchange (ETDEWEB)

    Kustandi, Tanu Suryadi; Low, Hong Yee [Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore); Choo, Jian Huei; Sinha, Sujeet K, E-mail: hy-low@imre.a-star.edu.s, E-mail: mpesks@nus.edu.s [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2010-01-13

    Wear is a major obstacle limiting the useful life of implanted ultra-high molecular weight polyethylene (UHMWPE) components in total joint arthroplasty. It has been a continuous effort in the implant industry to reduce the frictional wear problem of UHMWPE by improving the structure, morphology and mechanical properties of the polymer. In this paper, a new paradigm that utilizes nanoimprint lithography (NIL) in producing textures on the surface of UHMWPE is proposed to efficiently improve the tribological properties of the polymer. Friction and wear experiments were conducted on patterned and controlled (non-patterned) UHMWPE surfaces using a commercial tribometer, mounted with a silicon nitride ball, under a dry-sliding condition with normal loads ranging from 60 to 200 mN. It has been shown that the patterned UHMWPE surface showed a reduction in the coefficient of friction between 8% and 35% as compared with the controlled (non-patterned) surface, depending on the magnitude of the normal load. Reciprocating wear experiments also showed that the presence of surface textures on the polymer resulted in lower wear depth and width, with minimal material transfer to the sliding surface.

  19. Laser textured superhydrophobic surfaces and their applications for homogeneous spot deposition

    Science.gov (United States)

    Ta, Van Duong; Dunn, Andrew; Wasley, Thomas J.; Li, Ji; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Esenturk, Emre; Connaughton, Colm; Shephard, Jonathan D.

    2016-03-01

    This work reports the laser surface modification of 304S15 stainless steel to develop superhydrophobic properties and the subsequent application for homogeneous spot deposition. Superhydrophobic surfaces, with steady contact angle of ∼154° and contact angle hysteresis of ∼4°, are fabricated by direct laser texturing. In comparison with common pico-/femto-second lasers employed for this patterning, the nanosecond fiber laser used in this work is more cost-effective, compact and allows higher processing rates. The effect of laser power and scan line separation on surface wettability of textured surfaces are investigated and optimized fabrication parameters are given. Fluid flows and transportations of polystyrene (PS) nanoparticles suspension droplets on the processed surfaces and unprocessed wetting substrates are investigated. After evaporation is complete, the coffee-stain effect is observed on the untextured substrates but not on the superhydrophobic surfaces. Uniform deposition of PS particles on the laser textured surfaces is achieved and the deposited material is confined to smaller area.

  20. Study on tribological properties of multi-layer surface texture on Babbitt alloys surface

    Science.gov (United States)

    Zhang, Dongya; Zhao, Feifei; Li, Yan; Li, Pengyang; Zeng, Qunfeng; Dong, Guangneng

    2016-12-01

    To improve tribological properties of Babbitt alloys, multi-layer surface texture consisted of the main grooves and secondary micro-dimples are fabricated on the Babbitt substrate through laser pulse ablation. The tribological behaviors of multi-layer surface texture are investigated using a rotating type pin-on-disc tribo-meter under variation sliding speeds, and the film pressure distributions on the textured surfaces are simulated using computational fluid dynamics (CFD) method for elucidating the possible mechanisms. The results suggest that: (i) the multi-layer surface texture can reduce friction coefficient of Babbitt alloy, which has lowest friction coefficient of 0.03, in case of the groove parameter of 300 μm width and 15% of area density; (ii) the improvement effect may be more sensitive to the groove area density and the siding speed, and the textured surface with lower area density has lower friction coefficient under high sliding speed. Based on the reasons of (i) the secondary micro-dimples on Babbitt alloy possesses a hydrophobicity surface and (ii) the CFD analysis indicates that main grooves enhancing hydrodynamic effect, thus the multi-layer surface texture is regarded as dramatically improve the lubricating properties of the Babbitt alloy.

  1. Lubrication of textured surfaces: a general theory for flow and shear stress factors.

    Science.gov (United States)

    Scaraggi, Michele

    2012-08-01

    We report on a mean field theory of textured surface lubrication. We study the fluid flow dynamics occurring at the interface as a function of the texture characteristics, e.g. texture area density, shape and distribution of microstructures, and local slip lengths. The present results may be very important for the investigation of tailored microtextured surfaces for low-friction hydrodynamic applications.

  2. Wetting theory for small droplets on textured solid surfaces

    CERN Document Server

    Kim, Donggyu; Ryu, Seunghwa

    2016-01-01

    Conventional wetting theories on rough surfaces with Wenzel, Cassie-Baxter, and Penetrate modes suggest the possibility of tuning the contact angle by adjusting the surface texture. Despite decades of intensive study, there are still many experimental results that are not well understood because conventional wetting theory, which assume an infinite droplet size, has been used to explain measurements of finite-sized droplets. In this study, we suggest a wetting theory that is applicable to any droplet size based on the free energy landscape analysis of various wetting modes of finite-sized droplets on a 2D textured surface. The key finding of our study is that there are many quantized wetting angles with local free energy minima; the implication of this is remarkable. We find that the conventional theories can predict the contact angle at the global free energy minimum if the droplet size is 40 times or larger than the characteristic scale of the surface roughness. Furthermore, we confirm that the pinning orig...

  3. Modulated surface textures for enhanced scattering in thin-film silicon solar cells

    NARCIS (Netherlands)

    Isabella, O.; Battaglia, C.; Ballif, C.; Zeman, M.

    2012-01-01

    Nano-scale randomly textured front transparent oxides are superposed on micro-scale etched glass substrates to form modulated surface textures. The resulting enhanced light scattering is implemented in single and double junction thin-film silicon solar cells.

  4. Surface Modification of Textured Dielectrics and Their Wetting Behavior

    Science.gov (United States)

    Kumar, Vijay; Dhillon, Ajaypal Singh; Sharma, Niti Nipun

    2017-02-01

    Controlling the wettability on dielectric materials is a classical topic in surface engineering. Surface texturing and deposition of self-assembled monolayers (SAMs) are major approaches to achieve lower or higher water contact angle ( θ c) and thereby making surface less or more wettable (more hydrophobic). Dielectric surfaces wetting has been engineered by surface modification and has been shown to achieve θ c to a maximum of 120° ± 5°. Further improvement in θ c to an extent greater than 150° ± 5° is desired to render the surface superhydrophobic. We report in this work an achievement of θ c > 150° ± 5° by combining the plasma-treated surface and octadecyltrichlorosilane (OTS) SAMs deposition on dielectrics, and this had been shown on dielectric ranging from low- k to high- k values. The improvement in wetting behavior and quality of dielectric surface with monolayer on plasma-treated surfaces are (is) investigated and characterized using atomic-force microscope (AFM), scanning electron microscope (SEM), contact angle goniometer, and Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) and are compared with untreated dielectric surface with OTS monolayers.

  5. Surface Modification of Textured Dielectrics and Their Wetting Behavior

    Science.gov (United States)

    Kumar, Vijay; Dhillon, Ajaypal Singh; Sharma, Niti Nipun

    2017-01-01

    Controlling the wettability on dielectric materials is a classical topic in surface engineering. Surface texturing and deposition of self-assembled monolayers (SAMs) are major approaches to achieve lower or higher water contact angle (θ c) and thereby making surface less or more wettable (more hydrophobic). Dielectric surfaces wetting has been engineered by surface modification and has been shown to achieve θ c to a maximum of 120° ± 5°. Further improvement in θ c to an extent greater than 150° ± 5° is desired to render the surface superhydrophobic. We report in this work an achievement of θ c > 150° ± 5° by combining the plasma-treated surface and octadecyltrichlorosilane (OTS) SAMs deposition on dielectrics, and this had been shown on dielectric ranging from low-k to high-k values. The improvement in wetting behavior and quality of dielectric surface with monolayer on plasma-treated surfaces are (is) investigated and characterized using atomic-force microscope (AFM), scanning electron microscope (SEM), contact angle goniometer, and Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) and are compared with untreated dielectric surface with OTS monolayers.

  6. Fast Characterization of Moving Samples with Nano-Textured Surfaces

    CERN Document Server

    Madsen, Morten Hannibal; Zalkovskij, Maksim; Karamehmedović, Mirza; Garnæs, Jørgen

    2015-01-01

    We characterize nano-textured surfaces by optical diffraction techniques using an adapted commercial light microscope with two detectors, a CCD camera and a spectrometer. The acquisition and analyzing time for the topological parameters height, width, and sidewall angle is only a few milliseconds of a grating. We demonstrate that the microscope has a resolution in the nanometer range, also in an environment with many vibrations, such as a machine floor. Furthermore, we demonstrate an easy method to find the area of interest with the integrated CCD camera.

  7. Droplets impact on textured surfaces: Mesoscopic simulation of spreading dynamics

    Science.gov (United States)

    Wang, Yuxiang; Chen, Shuo

    2015-02-01

    Superhydrophobic surfaces have attracted much attention due to their excellent water-repellent property. In the present study, droplets in the ideal Cassie state were focused on, and a particle-based numerical method, many-body dissipative particle dynamics, was employed to explore the mechanism of droplets impact on textured surfaces. A solid-fluid interaction with three linear weight functions was used to generate different wettability and a simple but efficient method was introduced to compute the contact angle. The simulated results show that the static contact angle is in good agreement with the Cassie-Baxter formula for smaller ∅S and Fa, but more deviation will be produced for larger ∅S and Fa, and it is related to the fact that the Cassie-Baxter theory does not consider the contact angle hysteresis effect in their formula. Furthermore, high impact velocity can induce large contact angle hysteresis on textured surfaces with larger ∅S and Fa. The typical time-based evolutions of the spreading diameter were simulated, and they were analyzed from an energy transformation viewpoint. These results also show that the dynamical properties of droplet, such as rebounding or pinning, contact time and maximum spreading diameters, largely depend on the comprehensive effects of the material wettability, fraction of the pillars and impact velocities of the droplets.

  8. The effect of surface texture on the kinetic friction of a nanowire on a substrate

    Science.gov (United States)

    Xie, Hongtao; Mead, James; Wang, Shiliang; Huang, Han

    2017-01-01

    The friction between Al2O3 nanowires and silicon substrates of different surface textures was characterised by use of optical manipulation. It was found that surface textures had significant effect on both the friction and the effective contact area between a nanowire and a substrate. A genetic algorithm was developed to determine the effective contact area between the nanowire and the textured substrate. The frictional force was found to be nearly proportional to the effective contact area, regardless of width, depth, spacing and orientation of the surface textures. Interlocking caused by textured grooves was not observed in this study. PMID:28322351

  9. Analysis of Surface Texturization of Solar Cells by Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Hsiao-Yen Chung

    2008-01-01

    Full Text Available The purpose of this paper is to develop a simple new model, based on the classic molecular dynamics simulation (MD, alternative to complex electron-photon interactions to analyze the surface texturization of solar cells. This methodology can easily propose the absorptance differences between texturing and nontexturing solar cells. To verify model feasibility, this study simulates square, pyramidal, and semicircular texturization surfaces. Simulations show that surface texturization effectively increases the absorptance of incident light for solar cells, and this paper presents optimal texturization shapes. The MD model can also be potentially used to predict the efficiency promotion in any optical reflection-absorption cases.

  10. Numerical analysis of monocrystalline silicon solar cells with fine nanoimprinted textured surface

    Science.gov (United States)

    Yoshinaga, Seiya; Ishikawa, Yasuaki; Araki, Shinji; Honda, Tatsuki; Jiang, Yunjiang; Uraoka, Yukiharu

    2017-02-01

    We investigated the surface reflectance of nanoimprinted textures on silicon. Zirconium oxide, which is a wide-bandgap inorganic dielectric material, was used as the texturing material. We performed several calculations to optimize the textures for the production of high-efficiency bulk-type monocrystalline silicon solar cells. Our analysis revealed that nanoimprinted textured solar cells exhibit a lower reverse saturation current density than a solar cell with a conventional etched texture. It was also confirmed that the photocarrier generation rate for a solar cell with a submicron-scale nanoimprinted texture has little dependence on the texture shape. Furthermore, the weighted average reflectance of an optimized nanoimprinted textured solar cell was substantially reduced to 3.72%, suggesting that texture formation by nanoimprint lithography is an extremely effective technology for producing high-efficiency solar cells at a low cost.

  11. Use of biomimetic hexagonal surface texture in friction against lubricated skin.

    Science.gov (United States)

    Tsipenyuk, Alexey; Varenberg, Michael

    2014-05-01

    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.

  12. Reliable Classification of Geologic Surfaces Using Texture Analysis

    Science.gov (United States)

    Foil, G.; Howarth, D.; Abbey, W. J.; Bekker, D. L.; Castano, R.; Thompson, D. R.; Wagstaff, K.

    2012-12-01

    Communication delays and bandwidth constraints are major obstacles for remote exploration spacecraft. Due to such restrictions, spacecraft could make use of onboard science data analysis to maximize scientific gain, through capabilities such as the generation of bandwidth-efficient representative maps of scenes, autonomous instrument targeting to exploit targets of opportunity between communications, and downlink prioritization to ensure fast delivery of tactically-important data. Of particular importance to remote exploration is the precision of such methods and their ability to reliably reproduce consistent results in novel environments. Spacecraft resources are highly oversubscribed, so any onboard data analysis must provide a high degree of confidence in its assessment. The TextureCam project is constructing a "smart camera" that can analyze surface images to autonomously identify scientifically interesting targets and direct narrow field-of-view instruments. The TextureCam instrument incorporates onboard scene interpretation and mapping to assist these autonomous science activities. Computer vision algorithms map scenes such as those encountered during rover traverses. The approach, based on a machine learning strategy, trains a statistical model to recognize different geologic surface types and then classifies every pixel in a new scene according to these categories. We describe three methods for increasing the precision of the TextureCam instrument. The first uses ancillary data to segment challenging scenes into smaller regions having homogeneous properties. These subproblems are individually easier to solve, preventing uncertainty in one region from contaminating those that can be confidently classified. The second involves a Bayesian approach that maximizes the likelihood of correct classifications by abstaining from ambiguous ones. We evaluate these two techniques on a set of images acquired during field expeditions in the Mojave Desert. Finally, the

  13. The effect of controlled microrobotized blasting on implant surface texturing and early osseointegration.

    Science.gov (United States)

    Gil, Luiz F; Marin, Charles; Teixeira, Hellen; Marão, Heloisa F; Tovar, Nick; Khan, Rehan; Bonfante, Estevam A; Janal, Malvin; Coelho, Paulo G

    2016-02-01

    Surface topography modifications have become a key strategy for hastening the host-to-implant response to implantable materials. The present study evaluated the effect of three different carefully controlled surface texture patterns achieved through microrobotized blasting (controlled to high, medium and low roughness) relative to a larger scale blasting procedure (control) in early osseointegration in a canine model. Four commercially pure grade 2 titanium alloy implants (one of each surface) were bilaterally placed in the radii of six beagle dogs and allowed end points of 1 and 6 weeks in vivo. Following sacrifice, implants in bone were non-decalcified processed for bone morphologic and histometric (bone-to-implant contact; bone area fraction occupancy) evaluation. Surface topography was characterized by scanning electron microscopy and optical interferometry. Results showed initial osteogenic tissue interaction at one week and new bone in intimate contact with all implant surfaces at 6 weeks. At 1 and 6 weeks in vivo, higher bone-to-implant and bone area fraction occupancy were observed for the high texture pattern microrobotized blasted surface relative to others.

  14. Ethnicity prediction and classification from iris texture patterns: A survey on recent advances

    CSIR Research Space (South Africa)

    Mabuza-Hocquet, Gugulethu

    2017-03-01

    Full Text Available The prediction and classification of ethnicity based on iris texture patterns using image processing, artificial intelligence and computer vision techniques is still a recent topic in iris biometrics. While the large body of knowledge and research...

  15. Wetting theory for small droplets on textured solid surfaces

    Science.gov (United States)

    Kim, Donggyu; Pugno, Nicola M.; Ryu, Seunghwa

    2016-11-01

    Conventional wetting theories on rough surfaces with Wenzel, Cassie-Baxter, and Penetrate modes suggest the possibility of tuning the contact angle by adjusting the surface texture. Despite decades of intensive study, there are still many experimental results that are not well understood because conventional wetting theory, which assumes an infinite droplet size, has been used to explain measurements of finite-sized droplets. Here, we suggest a wetting theory applicable to a wide range of droplet size for the three wetting modes by analyzing the free energy landscape with many local minima originated from the finite size. We find that the conventional theory predicts the contact angle at the global minimum if the droplet size is about 40 times or larger than the characteristic scale of the surface roughness, regardless of wetting modes. Furthermore, we obtain the energy barrier of pinning which can induce the contact angle hysteresis as a function of geometric factors. We validate our theory against experimental results on an anisotropic rough surface. In addition, we discuss the wetting on non-uniformly rough surfaces. Our findings clarify the extent to which the conventional wetting theory is valid and expand the physical understanding of wetting phenomena of small liquid drops on rough surfaces.

  16. Combined Effect of Textured Patterns and Graphene Flake Additives on Tribological Behavior under Boundary Lubrication.

    Science.gov (United States)

    Cai, Zhen-bing; Zhao, Lei; Zhang, Xu; Yue, Wen; Zhu, Min-hao

    2016-01-01

    A ball-on-plate wear test was employed to investigate the effectiveness of graphene (GP) nanoparticles dispersed in a synthetic-oil-based lubricant in reducing wear. The effect by area ratio of elliptically shaped dimple textures and elevated temperatures were also explored. Pure PAO4 based oil and a mixture of this oil with 0.01 wt% GP were compared as lubricants. At pit area ratio of 5%, GP-base oil effectively reduced friction and wear, especially at 60 and 100 °C. Under pure PAO4 oil lubrication, the untextured surfaces gained low friction coefficients (COFs) and wear rates under 60 and 100 °C. With increasing laser--texture area ratio, the COF and wear rate decreased at 25 and 150 °C but increased at 60 and 100 °C. Under the GP-based oil lubrication, the textured surface with 5% area ratio achieved the lowest COF among those of the area ratios tested at all test temperatures. Meanwhile, the textured surface with 20% area ratio obtained the highest COF among those of the area ratios. With the joint action of GP and texture, the textured surface with 10% area ratio exhibited the best anti-wear performance among all of the textured surfaces at all test temperatures.

  17. Combined Effect of Textured Patterns and Graphene Flake Additives on Tribological Behavior under Boundary Lubrication

    Science.gov (United States)

    Cai, Zhen-bing; Zhao, Lei; Zhang, Xu; Yue, Wen; Zhu, Min-hao

    2016-01-01

    A ball-on-plate wear test was employed to investigate the effectiveness of graphene (GP) nanoparticles dispersed in a synthetic-oil-based lubricant in reducing wear. The effect by area ratio of elliptically shaped dimple textures and elevated temperatures were also explored. Pure PAO4 based oil and a mixture of this oil with 0.01 wt% GP were compared as lubricants. At pit area ratio of 5%, GP-base oil effectively reduced friction and wear, especially at 60 and 100°C. Under pure PAO4 oil lubrication, the untextured surfaces gained low friction coefficients (COFs) and wear rates under 60 and 100°C. With increasing laser—texture area ratio, the COF and wear rate decreased at 25 and 150°C but increased at 60 and 100°C. Under the GP-based oil lubrication, the textured surface with 5% area ratio achieved the lowest COF among those of the area ratios tested at all test temperatures. Meanwhile, the textured surface with 20% area ratio obtained the highest COF among those of the area ratios. With the joint action of GP and texture, the textured surface with 10% area ratio exhibited the best anti-wear performance among all of the textured surfaces at all test temperatures. PMID:27054762

  18. Fabrication, surface properties, and origin of superoleophobicity for a model textured surface.

    Science.gov (United States)

    Zhao, Hong; Law, Kock-Yee; Sambhy, Varun

    2011-05-17

    Inspired by the superhydrophobic effect displayed in nature, we set out to mimic the interplay between the chemistry and physics in the lotus leaf to see if the same design principle can be applied to control wetting and adhesion between toners and inks on various printing surfaces. Since toners and inks are organic materials, superoleophobicity has become our design target. In this work, we report the design and fabrication of a model superoleophobic surface on silicon wafer. The model surface was created by photolithography, consisting of texture made of arrays of ∼3 μm diameter pillars, ∼7 μm in height with a center-to-center spacing of 6 μm. The surface was then made oleophobic with a fluorosilane coating, FOTS, synthesized by the molecular vapor deposition technique with tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane. Contact angle measurement shows that the surface exhibits super repellency toward water and oil (hexadecane) with a water and hexadecane contact angles at 156° and 158°, respectively. Since the sliding angles for both liquids are also very small (∼10°), we conclude that the model surface is both superhydrophobic and superoleophobic. By comparing with the contact angle data of the bare silicon surfaces (both smooth and textured), we also conclude that the superoleophobicity is a result of both surface texturing and fluorination. Results from investigations of the effects of surface modification and pillar geometry indicate that both surface oleophobicity and pillar geometry are contributors to the superoleophobicity. More specifically, we found that superoleophobicity can only be attained on our model textured surface when the flat surface coating has a relatively high oleophobicity (i.e., with a hexadecane contact angle of >73°). SEM examination of the pillars with higher magnification reveals that the side wall in each pillar is not smooth; rather it consists of a ∼300 nm wavy structure (due to the Bosch etching process

  19. Experimental study on effect of surface vibration on micro textured surfaces with hydrophobic and hydrophilic materials

    Science.gov (United States)

    Yao, Chun-Wei; Lai, Chen-Ling; Alvarado, Jorge L.; Zhou, Jiang; Aung, Kendrick T.; Mejia, Jose E.

    2017-08-01

    Artificial hydrophobic surfaces have been studied in the last ten years in an effort to understand the effects of structured micro- and nano-scale features on droplet motion and self-cleaning mechanisms. Among these structured surfaces, micro-textured surfaces consisting of a combination of hydrophilic and hydrophobic materials have been designed, fabricated and characterized to understand how surface properties and morphology affect enhanced self-cleaning mechanisms. However, use of micro textured surfaces leads to a strong pinning effect that takes place between the droplets and the hydrophobic-hydrophilic edge, leading to a significant contact angle hysteresis effect. This research study focuses on the effects of surface vibrations on droplet shedding at different inclined angles on micro-textured surfaces. Surface vibration and shedding processes were experimentally characterized using a high speed imaging system. Experimental results show that droplets under the influence of surface vibration depict different contour morphologies when vibrating at different resonance frequencies. Moreover, droplet sliding angles can be reduced through surface vibration when the proper combination of droplet size and surface morphology is prescribed.

  20. Real-time color-based texture analysis for sophisticated defect detection on wooden surfaces

    Science.gov (United States)

    Polzleitner, Wolfgang; Schwingshakl, Gert

    2004-10-01

    We describe a scanning system developed for the classification and grading of surfaces of wooden tiles. The system uses color imaging sensors to analyse the surfaces of either hard- or softwood material in terms of the texture formed by grain lines (orientation, spatial frequency, and color), various types of colorization, and other defects like knots, heart wood, cracks, holes, etc. The analysis requires two major tracks: the assignment of a tile to its texture class (like A, B, C, 1, 2, 3, Waste), and the detection of defects that decrease the commercial value of the tile (heart wood, knots, etc.). The system was initially developed under the international IMS program (Intelligent Manufacturing Systems) by an industry consortium. During the last two years it has been further developed, and several industrial systems have been installed, and are presently used in production of hardwood flooring. The methods implemented reflect some of the latest developments in the field of pattern recognition: genetic feature selection, two-dimensional second order statistics, special color space transforms, and classification by neural networks. In the industrial scenario we describe, many of the features defining a class cannot be described mathematically. Consequently a focus was the design of a learning architecture, where prototype texture samples are presented to the system, which then automatically finds the internal representation necessary for classification. The methods used in this approach have a wide applicability to problems of inspection, sorting, and optimization of high-value material typically used in the furniture, flooring, and related wood manufacturing industries.

  1. Composite fillings microleakage after TEM00 Er: YAG laser texturing of human tooth enamel surface

    Science.gov (United States)

    Belikov, A. V.; Shatilova, K. V.; Skrypnik, A. V.; Fedotov, D. Y.

    2010-11-01

    The results of comparative investigation of methylene-blue microleakage between tooth enamel surface and light-cure composites various fluidity are presented. An enamel surface was treated by traditional methods or laser method (laser texturing). The role of adhesive systems is investigated at enamel texturing by the TEM00 Er: YAG radiation. It is shown, that microleakage was not observed when enamel was textured by the TEM00 Er: YAG laser radiation and covered with flowable composite "Revolution" (Kerr) without adhesive system. It is established, that for laser textured surfaces methylene-blue microleakage depends on distance between microcraters.

  2. Comparing Shape and Texture Features for Pattern Recognition in Simulation Data

    Energy Technology Data Exchange (ETDEWEB)

    Newsam, S; Kamath, C

    2004-12-10

    Shape and texture features have been used for some time for pattern recognition in datasets such as remote sensed imagery, medical imagery, photographs, etc. In this paper, we investigate shape and texture features for pattern recognition in simulation data. In particular, we explore which features are suitable for characterizing regions of interest in images resulting from fluid mixing simulations. Three texture features--gray level co-occurrence matrices, wavelets, and Gabor filters--and two shape features--geometric moments and the angular radial transform--are compared. The features are evaluated using a similarity retrieval framework. Our preliminary results indicate that Gabor filters perform the best among the texture features and the angular radial transform performs the best among the shape features. The feature which performs the best overall is dependent on how the groundtruth dataset is created.

  3. Thermodynamic analysis of shark skin texture surfaces for microchannel flow

    Science.gov (United States)

    Yu, Hai-Yan; Zhang, Hao-Chun; Guo, Yang-Yu; Tan, He-Ping; Li, Yao; Xie, Gong-Nan

    2016-09-01

    The studies of shark skin textured surfaces in flow drag reduction provide inspiration to researchers overcoming technical challenges from actual production application. In this paper, three kinds of infinite parallel plate flow models with microstructure inspired by shark skin were established, namely blade model, wedge model and the smooth model, according to cross-sectional shape of microstructure. Simulation was carried out by using FLUENT, which simplified the computation process associated with direct numeric simulations. To get the best performance from simulation results, shear-stress transport k-omega turbulence model was chosen during the simulation. Since drag reduction mechanism is generally discussed from kinetics point of view, which cannot interpret the cause of these losses directly, a drag reduction rate was established based on the second law of thermodynamics. Considering abrasion and fabrication precision in practical applications, three kinds of abraded geometry models were constructed and tested, and the ideal microstructure was found to achieve best performance suited to manufacturing production on the basis of drag reduction rate. It was also believed that bionic shark skin surfaces with mechanical abrasion may draw more attention from industrial designers and gain wide applications with drag-reducing characteristics.

  4. High friction and low wear properties of laser-textured ceramic surface under dry friction

    Science.gov (United States)

    Xing, Youqiang; Deng, Jianxin; Wu, Ze; Wu, Fengfang

    2017-08-01

    Two kinds of grooved textures with different spacing were fabricated on Al2O3/TiC ceramic surface by an Nd:YAG laser. The dry tribological properties of the textured samples were investigated by carrying out unidirectional rotary sliding friction and wear tests using a ball-on-disk tribometer. Results show that the laser textured samples exhibit higher friction coefficient and excellent wear resistance compared with the smooth sample under dry friction conditions. Furthermore, the texture morphology and spacing have a significant influence on the tribological properties. The sample with small texture spacing may be beneficial to increasing the friction coefficient, and the wavy-grooved sample exhibits the highest friction coefficient and shallowest wear depth. The increasing friction coefficient and anti-wear properties are attributed to the combined effects of the increased surface roughness, reduced real contact area, micro-cutting effect by the texture edges and entrapment of wear debris.

  5. Evaluation of Tire/Surfacing/Base Contact Stresses and Texture Depth

    Directory of Open Access Journals (Sweden)

    W.J.vdM. Steyn

    2015-03-01

    Full Text Available Tire rolling resistance has a major impact on vehicle fuel consumption. Rolling resistance is the loss of energy due to the interaction between the tire and the pavement surface. This interaction is a complicated combination of stresses and strains which depend on both tire and pavement related factors. These include vehicle speed, vehicle weight, tire material and type, road camber, tire inflation pressure, pavement surfacing texture etc. In this paper the relationship between pavement surface texture depth and tire/surfacing contact stress and area is investigated. Texture depth and tire/surfacing contact stress were measured for a range of tire inflation pressures on five different pavement surfaces. In the analysis the relationship between texture and the generated contact stresses as well as the contact stress between the surfacing and base layer are presented and discussed, and the anticipated effect of these relationships on the rolling resistance of vehicles on the surfacings, and subsequent vehicle fuel economy discussed.

  6. Impact of surface roughness and soil texture on mineral dust emission fluxes modeling

    Science.gov (United States)

    Menut, Laurent; PéRez, Carlos; Haustein, Karsten; Bessagnet, Bertrand; Prigent, Catherine; Alfaro, StéPhane

    2013-06-01

    Dust production models (DPM) used to estimate vertical fluxes of mineral dust aerosols over arid regions need accurate data on soil and surface properties. The Laboratoire Inter-Universitaire des Systemes Atmospheriques (LISA) data set was developed for Northern Africa, the Middle East, and East Asia. This regional data set was built through dedicated field campaigns and include, among others, the aerodynamic roughness length, the smooth roughness length of the erodible fraction of the surface, and the dry (undisturbed) soil size distribution. Recently, satellite-derived roughness length and high-resolution soil texture data sets at the global scale have emerged and provide the opportunity for the use of advanced schemes in global models. This paper analyzes the behavior of the ERS satellite-derived global roughness length and the State Soil Geographic data base-Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) using an advanced DPM in comparison to the LISA data set over Northern Africa and the Middle East. We explore the sensitivity of the drag partition scheme (a critical component of the DPM) and of the dust vertical fluxes (intensity and spatial patterns) to the roughness length and soil texture data sets. We also compare the use of the drag partition scheme to a widely used preferential source approach in global models. Idealized experiments with prescribed wind speeds show that the ERS and STATSGO-FAO data sets provide realistic spatial patterns of dust emission and friction velocity thresholds in the region. Finally, we evaluate a dust transport model for the period of March to July 2011 with observed aerosol optical depths from Aerosol Robotic Network sites. Results show that ERS and STATSGO-FAO provide realistic simulations in the region.

  7. Controlling cell adhesion via replication of laser micro/nano-textured surfaces on polymers

    Energy Technology Data Exchange (ETDEWEB)

    Koufaki, Niki; Ranella, Anthi; Barberoglou, Marios; Psycharakis, Stylianos; Fotakis, Costas; Stratakis, Emmanuel [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), 711 10, Heraklion, Crete (Greece); Aifantis, Katerina E, E-mail: stratak@iesl.forth.gr [Lab of Mechanics and Materials, Aristotle University of Thessaloniki, Thessaloniki (Greece)

    2011-12-15

    The aim of this study is to investigate cell adhesion and viability on highly rough polymeric surfaces with gradient roughness ratios and wettabilities prepared by microreplication of laser micro/nano-textured Si surfaces. Negative replicas on polydimethylsiloxane as well as positive ones on a photocurable (organically modified ceramic) and a biodegradable (poly(lactide-co-glycolide)) polymer have been successfully reproduced. The final culture substrates comprised from forests of micron-sized conical spikes exhibiting a range of roughness ratios and wettabilities, was achieved by changing the laser fluence used to fabricate the original template surfaces. Cell culture experiments were performed with the fibroblast NIH/3T3 and PC12 neuronal cell lines in order to investigate how these surfaces are capable of modulating different types of cellular responses including, viability, adhesion and morphology. The results showed a preferential adhesion of both cell types on the microstructured surfaces compared to the unstructured ones. In particular, the fibroblast NIH/3T3 cells show optimal adhesion for small roughness ratios, independent of the surface wettability and polymer type, indicating a non-monotonic dependence of cell adhesion on surface energy. In contrast, the PC12 cells were observed to adhere well to the patterned surfaces independent of the roughness ratio and wettability. These experimental findings are correlated with micromechanical measurements performed on the unstructured and replicated surfaces and discussed on the basis of previous observations describing the relation of cell response to surface energy and rigidity.

  8. Novel Unique Technique for Generating Ticket Identifier Using Image Texture Patterns

    Directory of Open Access Journals (Sweden)

    Mrs. Jayashree Katti

    2014-05-01

    Full Text Available A paperless ticketing system with an application through which user can purchase a mobile ticket. Once the purchasing information is provided, the mobile ticket can be sent to the respective users mobile. A new method is introduced to generate tickets in which texture pattern is generated for digest provided by md5. The ticket is sent in the format of image consisting of texture patterns. Ticket can be verified by ticket checker using an application developed to verify genuine ticket. This system will be a revolution in the m-commerce world.

  9. Bio-inspired design of ice-retardant devices based on benthic marine invertebrates: the effect of surface texture

    Directory of Open Access Journals (Sweden)

    Homayun Mehrabani

    2014-09-01

    Full Text Available Growth of ice on surfaces poses a challenge for both organisms and for devices that come into contact with liquids below the freezing point. Resistance of some organisms to ice formation and growth, either in subtidal environments (e.g., Antarctic anchor ice, or in environments with moisture and cold air (e.g., plants, intertidal begs examination of how this is accomplished. Several factors may be important in promoting or mitigating ice formation. As a start, here we examine the effect of surface texture alone. We tested four candidate surfaces, inspired by hard-shelled marine invertebrates and constructed using a three-dimensional printing process. We examined sub-polar marine organisms to develop sample textures and screened them for ice formation and accretion in submerged conditions using previous methods for comparison to data for Antarctic organisms. The sub-polar organisms tested were all found to form ice readily. We also screened artificial 3-D printed samples using the same previous methods, and developed a new test to examine ice formation from surface droplets as might be encountered in environments with moist, cold air. Despite limitations inherent to our techniques, it appears surface texture plays only a small role in delaying the onset of ice formation: a stripe feature (corresponding to patterning found on valves of blue mussels, Mytilus edulis, or on the spines of the Antarctic sea urchin Sterechinus neumayeri slowed ice formation an average of 25% compared to a grid feature (corresponding to patterning found on sub-polar butterclams, Saxidomas nuttalli. The geometric dimensions of the features have only a small (∼6% effect on ice formation. Surface texture affects ice formation, but does not explain by itself the large variation in ice formation and species-specific ice resistance observed in other work. This suggests future examination of other factors, such as material elastic properties and surface coatings, and their

  10. Pore scale investigation of textural effects on salt precipitation dynamics and patterns in drying porous media

    Science.gov (United States)

    Norouzi Rad, Mansoureh; Shokri, Nima

    2014-05-01

    During stage-1 evaporation from saline porous media, the capillary-induced liquid flow from the interior to the surface of porous media supplies the evaporative demand and transfers the dissolved salt toward the surface where evaporation occurs. This mode of mass transfer is influenced by several factors such as properties of the evaporating fluid and transport properties of porous media. In this work, we carried out a comprehensive pore scale study using X-ray micro-tomography to understand the effects of the texture on the dynamics of salt precipitation and deposition patterns in drying saline porous media. To do so, four different samples of quartz sand with different particle size distributions were used enabling us to constrain the effects of particle size on the salt precipitation patterns and dynamics. The packed beds were saturated with NaCl solution of 3 Molal and the X-ray imaging was continued for 22 hours with temporal resolution of 30 min resulting in pore scale information about the evaporation and precipitation dynamics. During evaporation from saline porous media, salt concentration continuously increases in preferential evaporating sites at the surface until it reaches the solubility limit which is followed by salt precipitation. Thanking to the pore-scale information, the effects of pore size distribution on the dynamics and patterns of salt precipitation were delineated with high spatial and temporal resolutions. Our results show more precipitation at the early stage of the evaporation in the case of sand with the larger particle size due to the presence of a fewer evaporation sites at the surface. Having more preferential evaporation sites at the surface of sand with finer particle sizes affects the patterns and thickness of the salt crust deposited on the surface such that a thinner salt crust was formed in the case of sand with smaller particle size which covered a larger area at the surface as opposed to the thicker patchy crusts in samples

  11. Surface texturing for adaptive Ag/MoS_2 solid lubricant plating

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The objective of this research is to prepare specially designed surface texture on hard steel surface by electrochemical micromachining (EM) and to incorporate electroless plated Ag/MoS2 solid lubricant coating into the dimples of EM textured steel surface to effectively reduce friction and wear of steel-steel contacts. The friction and wear behavior of the Ag/MoS2 solid lubricant coating on EM textured steel surface was evaluated in relation to the size and spacing of the dimples thereon. The microstructur...

  12. Identifying Differences and Similarities in Static and Dynamic Contact Angles between Nanoscale and Microscale Textured Surfaces Using Molecular Dynamics Simulations.

    Science.gov (United States)

    Slovin, Mitchell R; Shirts, Michael R

    2015-07-28

    We quantify some of the effects of patterned nanoscale surface texture on static contact angles, dynamic contact angles, and dynamic contact angle hysteresis using molecular dynamics simulations of a moving Lennard-Jones droplet in contact with a solid surface. We observe static contact angles that change with the introduction of surface texture in a manner consistent with theoretical and experimental expectations. However, we find that the introduction of nanoscale surface texture at the length scale of 5-10 times the fluid particle size does not affect dynamic contact angle hysteresis even though it changes both the advancing and receding contact angles significantly. This result differs significantly from microscale experimental results where dynamic contact angle hysteresis decreases with the addition of surface texture due to an increase in the receding contact angle. Instead, we find that molecular-kinetic theory, previously applied only to nonpatterned surfaces, accurately describes dynamic contact angle and dynamic contact angle hysteresis behavior as a function of terminal fluid velocity. Therefore, at length scales of tens of nanometers, the kinetic phenomena such as contact line pinning observed at larger scales become insignificant in comparison to the effects of molecular fluctuations for moving droplets, even though the static properties are essentially scale-invariant. These findings may have implications for the design of highly hierarchical structures with particular wetting properties. We also find that quantitatively determining the trends observed in this article requires the careful selection of system and analysis parameters in order to achieve sufficient accuracy and precision in calculated contact angles. Therefore, we provide a detailed description of our two-surface, circular-fit approach to calculating static and dynamic contact angles on surfaces with nanoscale texturing.

  13. A validated computational model for the design of surface textures in full-film lubricated sliding

    Science.gov (United States)

    Schuh, Jonathon; Lee, Yong Hoon; Allison, James; Ewoldt, Randy

    2016-11-01

    Our recent experimental work showed that asymmetry is needed for surface textures to decrease friction in full-film lubricated sliding (thrust bearings) with Newtonian fluids; textures reduce the shear load and produce a separating normal force. The sign of the separating normal force is not predicted by previous 1-D theories. Here we model the flow with the Reynolds equation in cylindrical coordinates, numerically implemented with a pseudo-spectral method. The model predictions match experiments, rationalize the sign of the normal force, and allow for design of surface texture geometry. To minimize sliding friction with angled cylindrical textures, an optimal angle of asymmetry β exists. The optimal angle depends on the film thickness but not the sliding velocity within the applicable range of the model. The model has also been used to optimize generalized surface texture topography while satisfying manufacturability constraints.

  14. Tribological Analysis of Ventral Scale Structure in a Python Regius in Relation to Laser Textured Surfaces

    CERN Document Server

    Abdel-aal, Hisham A

    2013-01-01

    Laser Texturing is one of the leading technologies applied to modify surface topography. To date, however, a standardized procedure to generate deterministic textures is virtually non-existent. In nature, especially in squamata, there are many examples of deterministic structured textures that allow species to control friction and condition their tribological response for efficient function. In this work, we draw a comparison between industrial surfaces and reptilian surfaces. We chose the python regius species as a bio-analogue with a deterministic surface. We first study the structural make up of the ventral scales of the snake (both construction and metrology). We further compare the metrological features of the ventral scales to experimentally recommended performance indicators of industrial surfaces extracted from open literature. The results indicate the feasibility of engineering a Laser Textured Surface based on the reptilian ornamentation constructs. It is shown that the metrological features, key to...

  15. Effect of surface penetrating sealant on surface texture and microhardness of composite resins.

    Science.gov (United States)

    Bertrand, M F; Leforestier, E; Muller, M; Lupi-Pégurier, L; Bolla, M

    2000-01-01

    The application of Fortify (Bisco, Lombard, IL), an unfilled resin, to the surface of composite resin restorations is intended to fill in defects in the surface that persist despite polishing, improve marginal integrity, and increase these materials' resistance to abrasion. The aim of this study was to observe the surface texture by scanning electron microscopy and measure the microhardness of the surface. For each sample of composite resin covered with glaze, 40 measurements were made of the thickness of the resin. Measurements of the Vickers microhardness included three samples of composite resin, three samples of glaze, and six samples of composite resin covered with glaze. A relationship was established between microhardness and thickness. Scanning electron microscopy showed a noticeable improvement in the surface texture. Nevertheless, areas were seen in which glaze seemed very thin or even completely absent. Measurements of the thickness ranged from 0-70 microm. The mean microhardness of composite resin was 65.8 +/- 0.7, while the mean hardness of glaze was 7.3 +/- 0.7. The microhardness of the double layer was reduced, depending on the thickness of the glazing resin. The capacity of glaze to mask surface defects of composite resin was shown, but it was difficult to obtain a regular surface with liquid resin. The application of this product caused a decrease of the microhardness of the composite resin's surface.

  16. Ultra short pulse laser generated surface textures for anti-ice applications in aviation

    NARCIS (Netherlands)

    Römer, G.W.; Del Cerro, D.A.; Sipkema, R.C.J.; Groenendijk, M.N.W.; Huis in 't Veld, A.J.

    2009-01-01

    By laser ablation with ultra short laser pulses in the pico- and femto-second range, well controlled dual scaled micro- and nano-scaled surface textures can be obtained. The micro-scale of the texture is mainly determined by the dimensions of the laser spot, whereas the superimposed nano-structure

  17. Ultra short pulse laser generated surface textures for anti-ice applications in aviation

    NARCIS (Netherlands)

    Römer, G.W.; Del Cerro, D.A.; Sipkema, R.C.J.; Groenendijk, M.N.W.; Huis in 't Veld, A.J.

    2009-01-01

    By laser ablation with ultra short laser pulses in the pico- and femto-second range, well controlled dual scaled micro- and nano-scaled surface textures can be obtained. The micro-scale of the texture is mainly determined by the dimensions of the laser spot, whereas the superimposed nano-structure i

  18. Antireflective surface patterned by rolling mask lithography

    Science.gov (United States)

    Seitz, Oliver; Geddes, Joseph B.; Aryal, Mukti; Perez, Joseph; Wassei, Jonathan; McMackin, Ian; Kobrin, Boris

    2014-03-01

    A growing number of commercial products such as displays, solar panels, light emitting diodes (LEDs and OLEDs), automotive and architectural glass are driving demand for glass with high performance surfaces that offer anti-reflective, self-cleaning, and other advanced functions. State-of-the-art coatings do not meet the desired performance characteristics or cannot be applied over large areas in a cost-effective manner. "Rolling Mask Lithography" (RML™) enables highresolution lithographic nano-patterning over large-areas at low-cost and high-throughput. RML is a photolithographic process performed using ultraviolet (UV) illumination transmitted through a soft cylindrical mask as it rolls across a substrate. Subsequent transfer of photoresist patterns into the substrate is achieved using an etching process, which creates a nanostructured surface. The current generation exposure tool is capable of patterning one-meter long substrates with a width of 300 mm. High-throughput and low-cost are achieved using continuous exposure of the resist by the cylindrical photomask. Here, we report on significant improvements in the application of RML™ to fabricate anti-reflective surfaces. Briefly, an optical surface can be made antireflective by "texturing" it with a nano-scale pattern to reduce the discontinuity in the index of refraction between the air and the bulk optical material. An array of cones, similar to the structure of a moth's eye, performs this way. Substrates are patterned using RML™ and etched to produce an array of cones with an aspect ratio of 3:1, which decreases the reflectivity below 0.1%.

  19. Experimental Study on Momentum Transfer of Surface Texture in Taylor-Couette Flow

    Science.gov (United States)

    Xue, Yabo; Yao, Zhenqiang; Cheng, De

    2017-05-01

    The behavior of Taylor-Couette (TC) flow has been extensively studied. However, no suitable torque prediction models exist for high-capacity fluid machinery. The Eckhardt-Grossmann-Lohse (EGL) theory, derived based on the Navier-Stokes equations, is proposed to model torque behavior. This theory suggests that surfaces are the significant energy transfer interfaces between cylinders and annular flow. This study mainly focuses on the effects of surface texture on momentum transfer behavior through global torque measurement. First, a power-law torque behavior model is built to reveal the relationship between dimensionless torque and the Taylor number based on the EGL theory. Second, TC flow apparatus is designed and built based on the CNC machine tool to verify the torque behavior model. Third, four surface texture films are tested to check the effects of surface texture on momentum transfer. A stereo microscope and three-dimensional topography instrument are employed to analyze surface morphology. Global torque behavior is measured by rotating a multi component dynamometer, and the effects of surface texture on the annular flow behavior are observed via images obtained using a high-speed camera. Finally, torque behaviors under four different surface conditions are fitted and compared. The experimental results indicate that surface textures have a remarkable influence on torque behavior, and that the peak roughness of surface texture enhances the momentum transfer by strengthening the fluctuation in the TC flow.

  20. Texture feature ranking with relevance learning to classify interstitial lung disease patterns

    NARCIS (Netherlands)

    Huber, Markus B.; Bunte, Kerstin; Nagarajan, Mahesh B.; Biehl, Michael; Ray, Lawrence A.; Wismueller, Axel

    2012-01-01

    Objective: The generalized matrix learning vector quantization (GMLVQ) is used to estimate the relevance of texture features in their ability to classify interstitial lung disease patterns in high-resolution computed tomography images. Methodology: After a stochastic gradient descent, the GMLVQ algo

  1. Pyramidal texturing of silicon surface via inorganic-organic hybrid alkaline liquor for heterojunction solar cells

    Science.gov (United States)

    Wang, Fengyou; Zhang, Xiaodan; Wang, Liguo; Jiang, Yuanjian; Wei, Changchun; Zhao, Ying

    2015-10-01

    We demonstrate a new class of silicon texturing approach based on inorganic (sodium hydroxide, NaOH) and organic (tetramethylammonium hydroxide, TMAH) alkaline liquor etching processes for photovoltaic applications. The first stage of inorganic alkaline etching textures the silicon surface rapidly with large pyramids and reduces the cost. The subsequent organic alkaline second-etching improves the coverage of small pyramids on the silicon surface and strip off the metallic contaminants produced by the first etching step. In addition, it could smoothen the surface of the pyramids to yield good morphology. In this study, the texturing duration of both etching steps was controlled to optimize the optical and electrical properties as well as the surface morphology and passivation characteristics of the silicon substrates. Compared with traditional inorganic NaOH texturing, this hybrid process yields smoother (111) facets of the pyramids, fewer residual Na+ ions on the silicon surface, and a shorter processing period. It also offers the advantage of lower cost compared with the organic texturing method based on the use of only TMAH. We applied this hybrid texturing process to fabricate silicon heterojunction solar cells, which showed a remarkable improvement compared with the cells based on traditional alkaline texturing processes.

  2. Crystallographic Texture Difference Between Center and Sub-Surface of Thin Cold-Drawn Pearlitic Steel Wires

    Science.gov (United States)

    Zhao, Tian-Zhang; Zhang, Guang-Liang; Song, Hong-Wu; Cheng, Ming; Zhang, Shi-Hong

    2014-09-01

    The texture difference between the center and sub-surface of pearlitic steel wires, which were manufactured by continuous cold drawing, was investigated by orientation distribution function based on electron back-scattered diffraction at different drawing passes. A perfect fiber texture parallel to drawing direction develops gradually with drawing strain increasing at the wire center, while at the sub-surface, a quasi fiber texture with the orientation nearly parallel to the circumferential direction is found. This texture at the sub-surface is softer than the perfect fiber texture in tension. The reasons for this texture difference and influences on the wire's mechanical properties are discussed.

  3. Experimental research of surface roughness and surface texture after laser cladding

    Science.gov (United States)

    Przestacki, Damian; Majchrowski, Radomir; Marciniak-Podsadna, Lidia

    2016-12-01

    The objective of the investigation was to identify surface integrity of machined parts after laser cladding. Surface analysis was made by using novel metrology methods: auto correlation and gradient distributions. An Infinite Focus Measurement Machine (IFM) has been used for the surface texture analysis. The study has been performed within a production facility during the prototyping process of new products. There are many methods available for geometric and surface topography measurements: contact and non-contact, micro and nanoscale approaches. An optical method based on the measurement of light reflected or scattered from the surface of an examined object can be used for this purpose. We have tested the application of an advanced 3D scanner for this purpose - optical scanner ATOS II. The scanner ATOS II represents the optical method, i.e. the digital light projection (DLP) method. The system consists of a projector and two digital cameras capable of supplying 1.4 million of measuring points per second. This method enables to scan elements from a few millimeters to a several dozen of meters in size. The roughness analysis is based on 2D measurements, which gave two-dimensional characteristics of the surface. In last decades, the metrology of the surface layer notes dynamical development as a science. During the last decades, many scientists and constructors became convinced that the third dimension should be added to the surface analysis. At present, 3D analysis of the surface geometry is widely accepted. In order to complete the topography analysis of the surface texture after laser cladding, our team worked out original program for 2D and 3D surface analysis. It was called TAS (topography analysis and simulation) and was based on Matlab software. Four modules were developed: the initial data processing module, basic parameters calculating module, data visualization module, and digital filtration module.

  4. Effect of Q-switched Laser Surface Texturing of Titanium on Osteoblast Cell Response

    Science.gov (United States)

    Voisey, K. T.; Scotchford, C. A.; Martin, L.; Gill, H. S.

    Titanium and its alloys are important biomedical materials. It is known that the surface texture of implanted medical devices affects cell response. Control of cell response has the potential to enhance fixation of implants into bone and, in other applications, to prevent undesired cell adhesion. The potential use of a 100W Q-switched YAG laser miller (DMG Lasertec 60 HSC) for texturing titanium is investigated. A series of regular features with dimensions of the order of tens of micrometers are generated in the surface of titanium samples and the cell response to these features is determined. Characterisation of the laser milled features reveals features with a lengthscale of a few microns superposed on the larger scale structures, this is attributed to resolidification of molten droplets generated and propelled over the surface by individual laser pulses. The laser textured samples are exposed to osteoblast cells and it is seen that cells do respond to the features in the laser textured surfaces.

  5. Effect of strontium tantalate surface texture on nickel nanoparticle dispersion by electroless deposition

    Energy Technology Data Exchange (ETDEWEB)

    Compean-González, C.L. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66451 (Mexico); Arredondo-Torres, V.M. [Facultad de Químico Farmacobiología, Universidad Michoacana de San Nicolás de Hidalgo, Tzintzuntzan #173, Col. Matamoros, Morelia, Michoacán C.P. 58240 (Mexico); Zarazúa-Morin, M.E. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66451 (Mexico); Figueroa-Torres, M.Z., E-mail: m.zyzlila@gmail.com [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66451 (Mexico)

    2015-09-15

    Highlights: • Efficient short-time procedure for nickel nanoparticles dispersion by electroless. • Nanoparticles are spherical in shape with an average size of 15 nm. • Influence of surface texture on deposition temperature and time was observed. • Nickel deposition can be done below 50 °C. - Abstract: The present work studies the effect of smooth and porous texture of Sr{sub 2}Ta{sub 2}O{sub 7} on its surface modification with nickel nanoparticles through electroless deposition technique. The influence of temperature to control Ni nanoparticles loading amount and dispersion were analyzed. Nitrogen adsorption isotherms were used to examine surface texture characteristics. The morphology was observed by scanning electron microscopy (MEB) equipped with an energy dispersive spectrometry system (EDS), which was used to determine the amount of deposited Ni. The material with smooth texture (SMT) consists of big agglomerates of semispherical shape particles of 400 nm. Whilst the porous texture (PRT) exhibit a pore-wall formed of needles shape particles of around 200 nm in size. Results indicated that texture characteristics strongly influence the deposition reaction rate; for PRT oxide, Ni deposition can be done from 20 °C while for SMT oxide deposition begins at 40 °C. Analysis of Sr{sub 2}Ta{sub 2}O{sub 7} surface indicated that in both textures, Ni nanoparticles with spherical shape in the range of 10–20 nm were obtained.

  6. Optimization-based design of surface textures for thin-film Si solar cells.

    Science.gov (United States)

    Sheng, Xing; Johnson, Steven G; Michel, Jurgen; Kimerling, Lionel C

    2011-07-04

    We numerically investigate the light-absorption behavior of thin-film silicon for normal-incident light, using surface textures to enhance absorption. We consider a variety of texture designs, such as simple periodic gratings and commercial random textures, and examine arbitrary irregular periodic textures designed by multi-parameter optimization. Deep and high-index-contrast textures exhibit strong anisotropic scattering that is outside the regime of validity of the Lambertian models commonly used to describe texture-induced absorption enhancement for normal incidence. Over a 900-1100 nm wavelength range, our optimized surface texture in two dimensions (2D) enhances absorption by a factor of 2.7 πn, considerably larger than the original πn Lambertian result and exceeding by almost 50% a recent generalization of Lambertian model for periodic structures in finite spectral range. However, the πn Lambertian limit still applies for isotropic incident light, and our structure obeys this limit when averaged over all the angles. Therefore, our design can be thought of optimizing the angle/enhancement tradeoff for periodic textures.

  7. Comparison and optimization of randomly textured surfaces in thin-film solar cells.

    Science.gov (United States)

    Rockstuhl, C; Fahr, S; Bittkau, K; Beckers, T; Carius, R; Haug, F-J; Söderström, T; Ballif, C; Lederer, F

    2010-09-13

    Using rigorous diffraction theory we investigate the scattering properties of various random textures currently used for photon management in thin-film solar cells. We relate the haze and the angularly resolved scattering function of these cells to the enhancement of light absorption. A simple criterion is derived that provides an explanation why certain textures operate more beneficially than others. Using this criterion we propose a generic surface profile that outperforms the available substrates. This work facilitates the understanding of the effect of randomly textured surfaces and provides guidelines towards their optimization.

  8. Mechanism of surface texture evolution in pure copper strips subjected to double rolling

    Directory of Open Access Journals (Sweden)

    Xiyong Wang

    2014-02-01

    Full Text Available Developing ultra-thin copper foils with different surface roughness and microstructure has important significance for improving the service performance and reducing the production cost of high-end circuit boards. In this paper, pure copper strips with initial cube texture were subjected to a double rolling process (deformation amount ranges from 50% to 95%, and the surface textures evolution law and mechanism of double-rolled strips were studied by an X-ray diffraction technique. The results show that when a deformation amount increased from 50% to 70%, the grains of two surfaces rotate away from the cube orientation, and the formed textures of two surfaces mainly consisted of C, S and B orientation components. The orientation density values for these three components on bright surface only had slight difference; the orientation density values for C and S components were much larger than that for B components on a matt surface. When the deformation amount increased to 90%, the increase extents of orientation density values for C and S components were obviously larger than that for B components on a bright surface; the increase extents of orientation density values for these three components were almost the same on the matt surface. It has been found that when deformation amount reaches 95%, the grains orientation of bright surface were relatively concentrated, and the orientation density value for C texture obviously increased to 11.68 and that for B texture was only 3.15; the grains orientation of matt surface were relatively dispersed, and the orientation density value for C texture increased to 9.26 and that for B texture obviously increased to 6.35, and the density values of these two textures had less difference. For the condition of strong compressive and shear stress on the bright surface, grains were mainly rotating to C texture orientation; compared with the bright surface, “semi-free” deformation condition on the matt surface is

  9. Image-space texture-based output-coherent surface flow visualization.

    Science.gov (United States)

    Huang, Jin; Pan, Zherong; Chen, Guoning; Chen, Wei; Bao, Hujun

    2013-09-01

    Image-space line integral convolution (LIC) is a popular scheme for visualizing surface vector fields due to its simplicity and high efficiency. To avoid inconsistencies or color blur during the user interactions, existing approaches employ surface parameterization or 3D volume texture schemes. However, they often require expensive computation or memory cost, and cannot achieve consistent results in terms of both the granularity and color distribution on different scales. This paper introduces a novel image-space surface flow visualization approach that preserves the coherence during user interactions. To make the noise texture under different viewpoints coherent, we propose to precompute a sequence of mipmap noise textures in a coarse-to-fine manner for consistent transition, and map the textures onto each triangle with randomly assigned and constant texture coordinates. Further, a standard image-space LIC is performed to generate the flow texture. The proposed approach is simple and GPU-friendly, and can be easily combined with various texture-based flow visualization techniques. By leveraging viewpoint-dependent backward tracing and mipmap noise phase, our method can be incorporated with the image-based flow visualization (IBFV) technique for coherent visualization of unsteady flows. We demonstrate consistent and highly efficient flow visualization on a variety of data sets.

  10. Comparative Study of Leaf Surface Texture and Ability to Expand of Cured Tobacco

    Directory of Open Access Journals (Sweden)

    Rohr R

    2014-12-01

    Full Text Available Tobacco leaf texture, appreciated by the difference of surface roughness of cured leaves, is studies with light microscopy and scanning electron microscopy (SEM. The leaf texture is obviously determined by the presence or absence of conical cellular protuberances on the adaxial side of the leaf. Considering the anatomic point of view, the leaf thickness, always more important when the leaf texture is open, is the only objective criterion which could be associated to the texture. The ultra-structural study with SEM and transmission electron microscopy (TEM demonstrates that the expansion capacity of tobacco doesn't rely on cytological factors such as cellular reserves or debris. The expansion capacity could be inversely proportional with the relative importance of the mesophyll comparing to palisade parenchyma. On the studied material, no direct relation between the leaf texture and the expansion capacity has been noticed.

  11. Optimization of hybrid antireflection structure integrating surface texturing and multi-layer interference coating

    Science.gov (United States)

    Kubota, Shigeru; Kanomata, Kensaku; Suzuki, Takahiko; Hirose, Fumihiko

    2014-10-01

    The antireflection structure (ARS) for solar cells is categorized to mainly two different techniques, i.e., the surface texturing and the single or multi-layer antireflection interference coating. In this study, we propose a novel hybrid ARS, which integrates moth eye texturing and multi-layer coat, for application to organic photovoltaics (OPVs). Using optical simulations based on the finite-difference time-domain (FDTD) method, we conduct nearly global optimization of the geometric parameters characterizing the hybrid ARS. The proposed optimization algorithm consists of two steps: in the first step, we optimize the period and height of moth eye array, in the absence of multi-layer coating. In the second step, we optimize the whole structure of hybrid ARS by using the solution obtained by the first step as the starting search point. The methods of the simple grid search and the Hooke and Jeeves pattern search are used for global and local searches, respectively. In addition, we study the effects of deviations in the geometric parameters of hybrid ARS from their optimized values. The design concept of hybrid ARS is highly beneficial for broadband light trapping in OPVs.

  12. Mapping lava flow textures using three-dimensional measures of surface roughness

    Science.gov (United States)

    Mallonee, H. C.; Kobs-Nawotniak, S. E.; McGregor, M.; Hughes, S. S.; Neish, C.; Downs, M.; Delparte, D.; Lim, D. S. S.; Heldmann, J. L.

    2016-12-01

    Lava flow emplacement conditions are reflected in the surface textures of a lava flow; unravelling these conditions is crucial to understanding the eruptive history and characteristics of basaltic volcanoes. Mapping lava flow textures using visual imagery alone is an inherently subjective process, as these images generally lack the resolution needed to make these determinations. Our team has begun mapping lava flow textures using visual spectrum imagery, which is an inherently subjective process involving the challenge of identifying transitional textures such as rubbly and slabby pāhoehoe, as these textures are similar in appearance and defined qualitatively. This is particularly problematic for interpreting planetary lava flow textures, where we have more limited data. We present a tool to objectively classify lava flow textures based on quantitative measures of roughness, including the 2D Hurst exponent, RMS height, and 2D:3D surface area ratio. We collected aerial images at Craters of the Moon National Monument (COTM) using Unmanned Aerial Vehicles (UAVs) in 2015 and 2016 as part of the FINESSE (Field Investigations to Enable Solar System Science and Exploration) and BASALT (Biologic Analog Science Associated with Lava Terrains) research projects. The aerial images were stitched together to create Digital Terrain Models (DTMs) with resolutions on the order of centimeters. The DTMs were evaluated by the classification tool described above, with output compared against field assessment of the texture. Further, the DTMs were downsampled and reevaluated to assess the efficacy of the classification tool at data resolutions similar to current datasets from other planetary bodies. This tool allows objective classification of lava flow texture, which enables more accurate interpretations of flow characteristics. This work also gives context for interpretations of flows with comparatively low data resolutions, such as those on the Moon and Mars. Textural maps based on

  13. Texture feature selection with relevance learning to classify interstitial lung disease patterns

    Science.gov (United States)

    Huber, Markus B.; Bunte, Kerstin; Nagarajan, Mahesh B.; Biehl, Michael; Ray, Lawrence A.; Wismueller, Axel

    2011-03-01

    The Generalized Matrix Learning Vector Quantization (GMLVQ) is used to estimate the relevance of texture features in their ability to classify interstitial lung disease patterns in high-resolution computed tomography (HRCT) images. After a stochastic gradient descent, the GMLVQ algorithm provides a discriminative distance measure of relevance factors, which can account for pairwise correlations between different texture features and their importance for the classification of healthy and diseased patterns. Texture features were extracted from gray-level co-occurrence matrices (GLCMs), and were ranked and selected according to their relevance obtained by GMLVQ and, for comparison, to a mutual information (MI) criteria. A k-nearest-neighbor (kNN) classifier and a Support Vector Machine with a radial basis function kernel (SVMrbf) were optimized in a 10-fold crossvalidation for different texture feature sets. In our experiment with real-world data, the feature sets selected by the GMLVQ approach had a significantly better classification performance compared with feature sets selected by a MI ranking.

  14. Textured surface structures formed using new techniques on transparent conducting Al-doped zinc oxide films prepared by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Minami, Tadatsugu [Optoelectronic Device System R& D Center, Kanazawa Institute of Technology, Nonoichi, Ishikawa 921-8501 (Japan); Miyata, Toshihiro, E-mail: tmiyata@neptune.kanazawa-it.ac.jp [Optoelectronic Device System R& D Center, Kanazawa Institute of Technology, Nonoichi, Ishikawa 921-8501 (Japan); Uozaki, Ryousuke [Optoelectronic Device System R& D Center, Kanazawa Institute of Technology, Nonoichi, Ishikawa 921-8501 (Japan); Sai, Hitoshi; Koida, Takashi [Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan)

    2016-09-01

    Surface-textured Al-doped ZnO (AZO) films formed using two new techniques based on magnetron sputtering deposition were developed by optimizing the light scattering properties to be suitable for transparent electrode applications in thin-film silicon solar cells. Scrambled egg-like surface-textured AZO films were prepared using a new texture formation technique that post-etched pyramidal surface-textured AZO films prepared under deposition conditions suppressing c-axis orientation. In addition, double surface-textured AZO films were prepared using another new texture formation technique that completely removed, by post-etching, the pyramidal surface-textured AZO films previously prepared onto the initially deposited low resistivity AZO films; simultaneously, the surface of the low resistivity films was slightly etched. However, the obtained very high haze value in the range from the near ultraviolet to visible light in the scrambled egg-like surface-textured AZO films did not contribute significantly to the obtainable photovoltaic properties in the solar cells fabricated using the films. Significant light scattering properties as well as a low sheet resistance could be achieved in the double surface-textured AZO films. In addition, a significant improvement of external quantum efficiency in the range from the near ultraviolet to visible light was achieved in superstrate-type n-i-p μc-Si:H solar cells fabricated using a double surface-textured AZO film prepared under optimized conditions as the transparent electrode. - Highlights: • Double surface-textured AZO films prepared using a new texture formation technique • Extensive light scattering properties with low sheet resistance achieved in the double surface-textured AZO films • Improved external quantum efficiency of μc-Si:H solar cells using a double surface-textured AZO film.

  15. Optimizing Geometry Mediated Skin Friction Drag on Riblet-Textured Surfaces

    Science.gov (United States)

    Raayai, Shabnam; McKinley, Gareth

    2016-11-01

    Micro-scale riblets have been shown to modify the skin friction drag on patterned surfaces. Shark skin is widely known as a natural example of this passive drag reduction mechanism and artificial riblet tapes have been previously used in the America's Cups tournament resulting in a 1987 victory. Previous experiments with riblet surfaces in turbulent boundary layer flow have shown 4-8% reduction in the skin friction drag. Our computations with sinusoidal riblet surfaces in high Reynolds number laminar boundary layer flow and experiments with V-grooves in laminar Taylor-Couette flow also show that the reduction in skin friction can be substantial and depends on the spacing and height of the riblets. In the boundary layer setting, this frictional reduction is also a function of the length of the plate in the flow direction, while in the Taylor Couette setting it depends on the gap size. In the current work, we use scaling arguments and conformal mapping to establish a simplified theory for laminar flow over V-groove riblets and explore the self-similarity of the velocity contours near the patterned surface. We combine these arguments with theoretical and numerical calculations using Matlab and OpenFOAM to show that the drag reduction achievable in laminar flow over riblet surfaces depends on a rescaled form of the Reynolds number combined with the aspect ratio of the texture (defined in terms of the ratio of the height to spacing of the riblets). We then use these results to explain the underlying physical mechanisms driving frictional drag reduction and offer recommendations for designing low drag surfaces.

  16. Systems and Methods of Laser Texturing of Material Surfaces and Their Applications

    Science.gov (United States)

    Gupta, Mool C. (Inventor); Nayak, Barada K. (Inventor)

    2014-01-01

    The surface of a material is textured and by exposing the surface to pulses from an ultrafast laser. The laser treatment causes pillars to form on the treated surface. These pillars provide for greater light absorption. Texturing and crystallization can be carried out as a single step process. The crystallization of the material provides for higher electric conductivity and changes in optical and electronic properties of the material. The method may be performed in vacuum or a gaseous environment. The gaseous environment may aid in texturing and/or modifying physical and chemical properties of the surfaces. This method may be used on various material surfaces, such as semiconductors, metals and their alloys, ceramics, polymers, glasses, composites, as well as crystalline, nanocrystalline, polycrystalline, microcrystalline, and amorphous phases.

  17. Local binary pattern texture-based classification of solid masses in ultrasound breast images

    Science.gov (United States)

    Matsumoto, Monica M. S.; Sehgal, Chandra M.; Udupa, Jayaram K.

    2012-03-01

    Breast cancer is one of the leading causes of cancer mortality among women. Ultrasound examination can be used to assess breast masses, complementarily to mammography. Ultrasound images reveal tissue information in its echoic patterns. Therefore, pattern recognition techniques can facilitate classification of lesions and thereby reduce the number of unnecessary biopsies. Our hypothesis was that image texture features on the boundary of a lesion and its vicinity can be used to classify masses. We have used intensity-independent and rotation-invariant texture features, known as Local Binary Patterns (LBP). The classifier selected was K-nearest neighbors. Our breast ultrasound image database consisted of 100 patient images (50 benign and 50 malignant cases). The determination of whether the mass was benign or malignant was done through biopsy and pathology assessment. The training set consisted of sixty images, randomly chosen from the database of 100 patients. The testing set consisted of forty images to be classified. The results with a multi-fold cross validation of 100 iterations produced a robust evaluation. The highest performance was observed for feature LBP with 24 symmetrically distributed neighbors over a circle of radius 3 (LBP24,3) with an accuracy rate of 81.0%. We also investigated an approach with a score of malignancy assigned to the images in the test set. This approach provided an ROC curve with Az of 0.803. The analysis of texture features over the boundary of solid masses showed promise for malignancy classification in ultrasound breast images.

  18. Experimental Study on Tribological Properties of Laser Textured 45 Steel Surface

    Directory of Open Access Journals (Sweden)

    Li Zhi Peng

    2016-01-01

    Full Text Available In order to study the influence of pits’ size parameters on the tribological properties of textured friction pairs, using the Nd:YAG laser micro machining system and the “single pulse at the same point, interval more times” processing technics to process the pits on the surface of 45 steel. The dimension parameters of pits texture were obtained by orthogonal experimental design. The tribological experiment of GCr15 pin/45 steel disc was carried out by UMT-2 test machine. The surface morphology of the specimens was analyzed by using scanning electron microscopy. The experimental results show that the pits texture on the surface of 45 steel can effectively reduce the friction coefficient and the wear on the condition of oil-rich lubrication. The textured specimen with diameter 60μm, depth 6μm and surface density 10% has the lowest friction coefficient, and the friction coefficient is reduced by 21% compared with the smooth specimen. By analyzing the wear morphology on the surface of 45 steel, it is found that the surface of pits texture can obviously reduce the wear.

  19. Femtosecond pulsed laser textured titanium surfaces with stable superhydrophilicity and superhydrophobicity

    Science.gov (United States)

    Li, Bao-jia; Li, Huang; Huang, Li-jing; Ren, Nai-fei; Kong, Xia

    2016-12-01

    A facile and highly-efficient laser scanning process coupled with a simple silanization modification was used to prepare textured titanium (Ti) surfaces with stable superhydrophilicity and superhydrophobicity. Femtosecond pulsed laser scanning along two mutually perpendicular directions led to the formation of binary structures featuring micrometer-scale spikes covered with nanometer-scale ripples. The period of the spikes significantly increased and the period of the ripples irregularly changed in the narrow range of 550-600 nm with the increase of laser fluence. The obtained laser-textured Ti surfaces were hydrophilic or even superhydrophilic, and the superhydrophilic laser-textured Ti surface using a laser fluence of 1.5 J/cm2 was observed to retain its wetting property after 30 days of storage in ambient atmosphere. After silanization, all the laser-textured Ti surfaces exhibited high hydrophobicity or superhydrophobicity, and the superhydrophobic laser-textured Ti surfaces using laser fluences of 1.5 and 1.8 J/cm2 remained stable when stored in air for over 30 days. The results imply the potential applications of these surfaces in a variety of fields.

  20. Substrate texture properties induce triatomine probing on bitten warm surfaces

    Directory of Open Access Journals (Sweden)

    Lorenzo Marcelo G

    2011-06-01

    Full Text Available Abstract Background In this work we initially evaluated whether the biting process of Rhodnius prolixus relies on the detection of mechanical properties of the substrate. A linear thermal source was used to simulate the presence of a blood vessel under the skin of a host. This apparatus consisted of an aluminium plate and a nickel-chrome wire, both thermostatized and presented at 33 and 36°C, respectively. To evaluate whether mechanical properties of the substrate affect the biting behaviour of bugs, this apparatus was covered by a latex membrane. Additionally, we evaluated whether the expression of probing depends on the integration of bilateral thermal inputs from the antennae. Results The presence of a latex cover on a thermal source induced a change in the biting pattern shown by bugs. In fact, with latex covered sources it was possible to observe long bites that were never performed in response to warm metal surfaces. The total number of bites was higher in intact versus unilaterally antennectomized insects. These bites were significantly longer in intact than in unilaterally antennectomized insects. Conclusions Our results suggest that substrate recognition by simultaneous input through thermal and mechanical modalities is required for triggering maxillary probing activity.

  1. Texturing of titanium (Ti6Al4V) medical implant surfaces with MHz-repetition-rate femtosecond and picosecond Yb-doped fiber lasers.

    Science.gov (United States)

    Erdoğan, Mutlu; Öktem, Bülent; Kalaycıoğlu, Hamit; Yavaş, Seydi; Mukhopadhyay, Pranab K; Eken, Koray; Ozgören, Kıvanç; Aykaç, Yaşar; Tazebay, Uygar H; Ilday, F Ömer

    2011-05-23

    We propose and demonstrate the use of short pulsed fiber lasers in surface texturing using MHz-repetition-rate, microjoule- and sub-microjoule-energy pulses. Texturing of titanium-based (Ti6Al4V) dental implant surfaces is achieved using femtosecond, picosecond and (for comparison) nanosecond pulses with the aim of controlling attachment of human cells onto the surface. Femtosecond and picosecond pulses yield similar results in the creation of micron-scale textures with greatly reduced or no thermal heat effects, whereas nanosecond pulses result in strong thermal effects. Various surface textures are created with excellent uniformity and repeatability on a desired portion of the surface. The effects of the surface texturing on the attachment and proliferation of cells are characterized under cell culture conditions. Our data indicate that picosecond-pulsed laser modification can be utilized effectively in low-cost laser surface engineering of medical implants, where different areas on the surface can be made cell-attachment friendly or hostile through the use of different patterns.

  2. Finite size effects on textured surfaces: recovering contact angles from vagarious drop edges.

    Science.gov (United States)

    Gauthier, Anaïs; Rivetti, Marco; Teisseire, Jérémie; Barthel, Etienne

    2014-02-18

    A clue to understand wetting hysteresis on superhydrophobic surfaces is the relation between receding contact angle and surface textures. When the surface textures are large, there is a significant distribution of local contact angles around the drop. As seen from the cross section, the apparent contact angle oscillates as the triple line recedes. Our experiments demonstrate that the origin of these oscillations is a finite size effect. Combining side and bottom views of the drop, we take into account the 3D conformation of the surface near the edge to evaluate an intrinsic contact angle from the oscillations of the apparent contact angle. We find that for drops receding on axisymmetric textures the intrinsic receding contact angle is the minimum value of the oscillation while for a square lattice it is the maximum.

  3. Self-similarity Based Editing of 3D Surface Textures Using Height and Albedo Maps

    Institute of Scientific and Technical Information of China (English)

    DONG Junyu; REN Jing; CHEN Guojiang

    2007-01-01

    This paper presents an inexpensive method for self-similarity based editing of real-world 3D surface textures by using height and albedo maps. Unlike self-similarity based 2D texture editing approaches which only make changes to pixel color or intensity values, this technique also allows surface geometry and reflectance of the captured 3D surface textures to be edited and relit using illumination conditions and viewing angles that differ from those of the original. A single editing operation at a given location affects all similar areas and produces changes on all images of the sample rendered under different conditions. Since surface height and albedo maps can be used to describe seabed topography and geologic features, which play important roles in many oceanic processes, the proposed method can be effectively employed in applications regarding visualization and simulation of oceanic phenomena.

  4. Droplet hysteresis investigation on non-wetting striped textured surfaces: A lattice Boltzmann study

    Science.gov (United States)

    Zheng, Rongye; Liu, Haihu; Sun, Jinju; Ba, Yan

    2014-10-01

    The Cassie-Baxter model is widely used to predict the apparent contact angles on textured super-hydrophobic surfaces. However, it has been challenged by some recent studies, since it does not consider contact angle hysteresis and surface structure characteristics near the contact line. The present study is to investigate the contact angle hysteresis on striped textured surfaces, and its elimination through vibrating the substrate. The two-phase flow is simulated by a recently proposed lattice Boltzmann model for high-density-ratio flows. Droplet evolutions under various initial contact angles are simulated, and it is found that different contact angles exist for the same textured surface. The importance of the contact line structure for droplet pinning is underlined via a study of droplet behavior on a composite substrate, with striped textured structure inside and flat structure outside. A “stick-jump” motion is found for the advancing contact line on the striped textured surface. Due to hysteresis, the contact angles after advancing are not consistent with the Cassie-Baxter model. The stable equilibrium is obtained through properly vibrating the substrate, and the resulted contact angles are consistent with Cassie's predictions.

  5. Effect of surface texture and working gap on the braking performance of the magnetorheological fluid brake

    Science.gov (United States)

    Wang, Na; Li, Dong Heng; Li Song, Wan; Chao Xiu, Shi; Zhi Meng, Xiang

    2016-10-01

    In this paper, the effect of the surface textures of braking disc on the braking performance is experimentally investigated under the conditions of different working gaps and applied currents. For this purpose, a new configuration of magnetorheological fluid brake (MRB) with adjustable working gap is developed to improve the manufacturing accuracy and cost, and to reduce the problem of replacing the braking disc. In addition, the braking discs with three types of surface texture are designed and machined. Based on the test bed developed for the proposed MRB, a series of experiments are carried out on the manufactured prototype and the results are presented to obtain the relationship among the surface texture of the braking disc, applied current, working gap and the braking performance. The results show that the braking torque is significantly influenced by the working gap and surface texture of the braking disc, and the maximum braking torque is obtained on the conditions of 0.25 mm working gap and the braking disc with square surface texture.

  6. Characteristics of laser textured silicon surface and effect of mud adhesion on hydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Ali, H. [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Khaled, M. [CHEM Department, King Fahd University of Petroleum & Minerals, Dhahran (Saudi Arabia); Al-Aqeeli, N.; Abu-Dheir, N. [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Varanasi, K.K. [Mechanical Engineering, Massachusetts Institute of Technology, Boston, MA (United States)

    2015-10-01

    Highlights: • Laser treatment increases surface microhardness and slightly lowers surface fracture toughness. • Residual stress formed is compressive and self-annealing effect of laser tracks lowers residual stress. • Nitride species lowers surface energy and adhesion work required to remove dust. • Mud residues do not have notable effect on fracture toughness and microhardness of treated surface. • Mud residues lower surface hydrophobicity. - Abstract: Laser gas assisted texturing of silicon wafer surface is carried out. Morphological and metallurgical changes in the treated layer are examined using the analytical tools. Microhardness and fracture toughness of the laser treated surface are measured using the indentation technique while residual stress formed is determined from the X-ray diffraction data. The hydrophobicity of the textured surfaces are assessed incorporating the contact angle data and compared with those of as received workpiece surfaces. Environmental dust accumulation and mud formation, due to air humidity, at the laser treated and as received workpiece surfaces are simulated and the effect of the mud residues on the properties of the laser treated surface are studied. The adhesion work due to the presence of the mud on the laser treated surface is also measured. It is found that laser textured surface composes of micro/nano poles and fibers, which in turn improves the surface hydrophobicity significantly. In addition, formation of nitride species contributes to microhardness increase and enhancement of surface hydrophobicity due to their low surface energy. The mud residues do not influence the fracture toughness and microhardness of the laser textured surface; however, they reduced the surface hydrophobicity significantly.

  7. HIGH AND LOW RESOLUTION TEXTURED MODELS OF COMPLEX ARCHITECTURAL SURFACES

    Directory of Open Access Journals (Sweden)

    E. K. Stathopoulou

    2012-09-01

    Full Text Available During the recent years it has become obvious that 3D technology, applied mainly with the use of terrestrial laser scanners (TLS is the most suitable technique for the complete geometric documentation of complex objects, whether they are monuments or architectural constructions in general. However, it is rather a challenging task to convert an acquired point cloud into a realistic 3D polygonal model that can simultaneously satisfy high resolution modeling and visualization demands. The aim of the visualization of a simple or complex object is to create a 3D model that best describes the reality within the computer environment. This paper is dedicated especially in the visualization of a complex object's 3D model, through high, as well as low resolution textured models. The object of interest for this study was the Almoina (Romanesque Door of the Cathedral of Valencia in Spain.

  8. High and Low Resolution Textured Models of Complex Architectural Surfaces

    Science.gov (United States)

    Stathopoulou, E. K.; Valanis, A.; Lerma, J. L.; Georgopoulos, A.

    2011-09-01

    During the recent years it has become obvious that 3D technology, applied mainly with the use of terrestrial laser scanners (TLS) is the most suitable technique for the complete geometric documentation of complex objects, whether they are monuments or architectural constructions in general. However, it is rather a challenging task to convert an acquired point cloud into a realistic 3D polygonal model that can simultaneously satisfy high resolution modeling and visualization demands. The aim of the visualization of a simple or complex object is to create a 3D model that best describes the reality within the computer environment. This paper is dedicated especially in the visualization of a complex object's 3D model, through high, as well as low resolution textured models. The object of interest for this study was the Almoina (Romanesque) Door of the Cathedral of Valencia in Spain.

  9. Wear Characterization of Cemented Carbides (WC–CoNi Processed by Laser Surface Texturing under Abrasive Machining Conditions

    Directory of Open Access Journals (Sweden)

    Shiqi Fang

    2017-06-01

    Full Text Available Cemented carbides are outstanding engineering materials widely used in quite demanding material removal applications. In this study, laser surface texturing is implemented for enhancing, at the surface level, the intrinsic bulk-like tribological performance of these materials. In this regard, hexagonal pyramids patterned on the cutting surface of a tungsten cemented carbide grade (WC–CoNi have been successfully introduced by means of laser surface texturing. It simulates the surface topography of conventional honing stones for abrasive application. The laser-produced structure has been tested under abrasive machining conditions with full lubrication. Wear of the structure has been characterized and compared, before and after the abrasive machining test, in terms of changes in geometry aspect and surface integrity. It is found that surface roughness of the machined workpiece was improved by the laser-produced structure. Wear characterization shows that laser treatment did not induce any significant damage to the cemented carbide. During the abrasive machining test, the structure exhibited a high wear resistance. Damage features were only discerned at the contacting surface, whereas geometrical shape of pyramids remained unchanged.

  10. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    Science.gov (United States)

    Sandoval Amador, A.; Carreño Garcia, H.; Escobar Rivero, P.; Peña Ballesteros, D. Y.; Estupiñán Duran, H. A.

    2016-02-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti6Al4V surfaces were evaluated. Ti6Al4V surfaces were textured using a CO2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment.

  11. Texture- and deformability-based surface recognition by tactile image analysis.

    Science.gov (United States)

    Khasnobish, Anwesha; Pal, Monalisa; Tibarewala, D N; Konar, Amit; Pal, Kunal

    2016-08-01

    Deformability and texture are two unique object characteristics which are essential for appropriate surface recognition by tactile exploration. Tactile sensation is required to be incorporated in artificial arms for rehabilitative and other human-computer interface applications to achieve efficient and human-like manoeuvring. To accomplish the same, surface recognition by tactile data analysis is one of the prerequisites. The aim of this work is to develop effective technique for identification of various surfaces based on deformability and texture by analysing tactile images which are obtained during dynamic exploration of the item by artificial arms whose gripper is fitted with tactile sensors. Tactile data have been acquired, while human beings as well as a robot hand fitted with tactile sensors explored the objects. The tactile images are pre-processed, and relevant features are extracted from the tactile images. These features are provided as input to the variants of support vector machine (SVM), linear discriminant analysis and k-nearest neighbour (kNN) for classification. Based on deformability, six household surfaces are recognized from their corresponding tactile images. Moreover, based on texture five surfaces of daily use are classified. The method adopted in the former two cases has also been applied for deformability- and texture-based recognition of four biomembranes, i.e. membranes prepared from biomaterials which can be used for various applications such as drug delivery and implants. Linear SVM performed best for recognizing surface deformability with an accuracy of 83 % in 82.60 ms, whereas kNN classifier recognizes surfaces of daily use having different textures with an accuracy of 89 % in 54.25 ms and SVM with radial basis function kernel recognizes biomembranes with an accuracy of 78 % in 53.35 ms. The classifiers are observed to generalize well on the unseen test datasets with very high performance to achieve efficient material

  12. Transition from Cassie to impaled state during drop impact on groove-textured solid surfaces.

    Science.gov (United States)

    Vaikuntanathan, V; Sivakumar, D

    2014-05-07

    Liquid drops impacted on textured surfaces undergo a transition from the Cassie state characterized by the presence of air pockets inside the roughness valleys below the drop to an impaled state with at least one of the roughness valleys filled with drop liquid. This occurs when the drop impact velocity exceeds a particular value referred to as the critical impact velocity. The present study investigates such a transition process during water drop impact on surfaces textured with unidirectional parallel grooves referred to as groove-textured surfaces. The process of liquid impalement into a groove in the vicinity of drop impact through de-pinning of the three-phase contact line (TPCL) beneath the drop as well as the critical impact velocity were identified experimentally from high speed video recordings of water drop impact on six different groove-textured surfaces made from intrinsically hydrophilic (stainless steel) as well as intrinsically hydrophobic (PDMS and rough aluminum) materials. The surface energy of various 2-D configurations of liquid-vapor interface beneath the drop near the drop impact point was theoretically investigated to identify the locally stable configurations and establish a pathway for the liquid impalement process. A force balance analysis performed on the liquid-vapor interface configuration just prior to TPCL de-pinning provided an expression for the critical drop impact velocity, Uo,cr, beyond which the drop state transitions from the Cassie to an impaled state. The theoretical model predicts that Uo,cr increases with the increase in pillar side angle, α, and intrinsic hydrophobicity whereas it decreases with the increase in groove top width, w, of the groove-textured surface. The quantitative predictions of the theoretical model were found to show good agreement with the experimental measurements of Uo,cr plotted against the surface texture geometry factor in our model, {tan(α/2)/w}(0.5).

  13. Capturing the surface texture and shape of pollen: a comparison of microscopy techniques.

    Directory of Open Access Journals (Sweden)

    Mayandi Sivaguru

    Full Text Available Research on the comparative morphology of pollen grains depends crucially on the application of appropriate microscopy techniques. Information on the performance of microscopy techniques can be used to inform that choice. We compared the ability of several microscopy techniques to provide information on the shape and surface texture of three pollen types with differing morphologies. These techniques are: widefield, apotome, confocal and two-photon microscopy (reflected light techniques, and brightfield and differential interference contrast microscopy (DIC (transmitted light techniques. We also provide a first view of pollen using super-resolution microscopy. The three pollen types used to contrast the performance of each technique are: Croton hirtus (Euphorbiaceae, Mabea occidentalis (Euphorbiaceae and Agropyron repens (Poaceae. No single microscopy technique provided an adequate picture of both the shape and surface texture of any of the three pollen types investigated here. The wavelength of incident light, photon-collection ability of the optical technique, signal-to-noise ratio, and the thickness and light absorption characteristics of the exine profoundly affect the recovery of morphological information by a given optical microscopy technique. Reflected light techniques, particularly confocal and two-photon microscopy, best capture pollen shape but provide limited information on very fine surface texture. In contrast, transmitted light techniques, particularly differential interference contrast microscopy, can resolve very fine surface texture but provide limited information on shape. Texture comprising sculptural elements that are spaced near the diffraction limit of light (~250 nm; NDL presents an acute challenge to optical microscopy. Super-resolution structured illumination microscopy provides data on the NDL texture of A. repens that is more comparable to textural data from scanning electron microscopy than any other optical

  14. Surface texture and percolation effects in microporous oriented films of polyolefins

    Science.gov (United States)

    Novikov, D. V.; Kuryndin, I. S.; Bukošek, V.; Elyashevich, G. K.

    2012-11-01

    The surface structure of polypropylene and polyethylene microporous films prepared by the extrusion of the polymer melt with the subsequent stages of annealing, uniaxial extension, and thermal fixation of the samples has been analyzed using scanning electron microscopy. It has been shown that percolation through pores corresponds to the axial texture of the surface with the channel structure described by the fractal cluster model. The transition from open pores (through-flow channels) to closed pores leads to the formation of surface regions with a biaxial texture. An increase in the density of the solid phase cluster is accompanied by the formation of a homogeneous biaxial texture with a period of alternation of the density in two mutually perpendicular directions, one of which coincides with the direction of orientation of the films.

  15. An analysis of type F2 software measurement standards for profile surface texture parameters

    Science.gov (United States)

    Todhunter, L. D.; Leach, R. K.; Lawes, S. D. A.; Blateyron, F.

    2017-06-01

    This paper reports on an in-depth analysis of ISO 5436 part 2 type F2 reference software for the calculation of profile surface texture parameters that has been performed on the input, implementation and output results of the reference software developed by the National Physical Laboratory (NPL), the National Institute of Standards and Technology (NIST) and Physikalisch-Technische Bundesanstalt (PTB). Surface texture parameters have been calculated for a selection of 17 test data files obtained from the type F1 reference data sets on offer from NPL and NIST. The surface texture parameter calculation results show some disagreements between the software methods of the National Metrology Institutes. These disagreements have been investigated further, and some potential explanations are given.

  16. Wetting Patterns and Nitrate Distributions in Layered-Textural Soils Under Drip Irrigation

    Institute of Scientific and Technical Information of China (English)

    LI Jiu-sheng; JI Hong-yan; LI Bei; LIU Yu-chun

    2007-01-01

    Laboratory experiments were conducted in different sequence and thickness of the soil layers to investigate the effects of layered-textural soils on wetting patterns and water and nitrate distributions from a surface point source under various combinations of application rate and applied volume. Three layered soils, including a sandy-over-sandy loam (SL), a sandy loam-over-sandy (LS), and a sandy loam-sandy-sandy loam (LSL), and two uniform soils (a uniform sandy loam and a uniform sandy soil) were tested. In the experiments, the application rate was varied from 0.69 to 3.86 L h-1 and the applied volume from 5.7 to 12.1 L. The experimental results demonstrated that the wetting patterns and water and nitrate distributions were greatly affected by the sequence and thickness of soil layers as well as the application rate and volume applied. An interface existing in the layered soils, whether a fine-over-coarse or a coarse-over-fine, had a common feature of limiting downward water movement and of increasing horizontal water movement. For the fine-over-coarse layered soils of LS and LSL, water and nitrate were uniformly distributed at a given depth in the top layer soil. For a coarse-over-fine layered soil of SL, however, water accumulated in the sublayer soil underneath the interface and a zone of lower nitrate concentration was observed. The effect of application rate on water distribution pattern was dependent upon soil layering. A minor influence of application rate on water distribution for the fine-over-coarse layered soils (LS and LSL) than for the uniform soils was found. To obtain a greater wetted depth through selecting the emitters having a smaller application rate, which is a common method in the system design for a uniform soil, may not be necessarily applied for the layered soils.Measurements of nitrate distribution showed that nitrate accumulated toward the boundary of the wetted volume for both the uniform and the layered soils. This suggests the

  17. Segmentation of Textures Defined on Flat vs. Layered Surfaces using Neural Networks: Comparison of 2D vs. 3D Representations.

    Science.gov (United States)

    Oh, Sejong; Choe, Yoonsuck

    2007-08-01

    Texture boundary detection (or segmentation) is an important capability in human vision. Usually, texture segmentation is viewed as a 2D problem, as the definition of the problem itself assumes a 2D substrate. However, an interesting hypothesis emerges when we ask a question regarding the nature of textures: What are textures, and why did the ability to discriminate texture evolve or develop? A possible answer to this question is that textures naturally define physically distinct (i.e., occluded) surfaces. Hence, we can hypothesize that 2D texture segmentation may be an outgrowth of the ability to discriminate surfaces in 3D. In this paper, we conducted computational experiments with artificial neural networks to investigate the relative difficulty of learning to segment textures defined on flat 2D surfaces vs. those in 3D configurations where the boundaries are defined by occluding surfaces and their change over time due to the observer's motion. It turns out that learning is faster and more accurate in 3D, very much in line with our expectation. Furthermore, our results showed that the neural network's learned ability to segment texture in 3D transfers well into 2D texture segmentation, bolstering our initial hypothesis, and providing insights on the possible developmental origin of 2D texture segmentation function in human vision.

  18. Influence Of Laser Beam Intensity On Geometry Parameters Of A Single Surface Texture Element

    Directory of Open Access Journals (Sweden)

    Antoszewski B.

    2015-09-01

    Full Text Available Laser surface texturing is used more and more often in modern machines for the implementation of variety of purposes such as for example intensification of lubrication, intensification of heat exchange, stimulation of microfluidics, increasing the chemical activity of the surface. Owing to the development of technologies using a concentrated energy flux, including laser microprocessing, it has become feasible. The present paper concentrates on the selection of parameters of laser microprocessing with picosecond pulses so as to obtain the highest efficiency and accuracy of the execution of a single texture element.

  19. Microplastics in the surface sediments from the Beijiang River littoral zone: Composition, abundance, surface textures and interaction with heavy metals.

    Science.gov (United States)

    Wang, Jundong; Peng, Jinping; Tan, Zhi; Gao, Yifan; Zhan, Zhiwei; Chen, Qiuqiang; Cai, Liqi

    2017-03-01

    While large quantities of studies on microplastics in the marine environment have been widely carried out, few were available in the freshwater environment. The occurrence and characteristics, including composition, abundance, surface texture and interaction with heavy metals, of microplastics in the surface sediments from Beijiang River littoral zone were investigated. The concentrations of microplastics ranged from 178 ± 69 to 544 ± 107 items/kg sediment. SEM images illustrated that pits, fractures, flakes and adhering particles were the common patterns of degradation. Chemical weathering of microplastics was also observed and confirmed by μ-FTIR. EDS spectra displayed difference in the elemental types of metals on the different surface sites of individual microplastic, indicating that some metals carried by microplastics were not inherent but were derived from the environment. The content of metals (Ni, Cd, Pb, Cu, Zn and Ti) in microplastics after ultrasonic cleaning has been analyzed by ICP-MS. Based on data from the long-term sorption of metals by microplastics and a comparison of metal burden between microplastics, macroplastics and fresh plastic products, we suggested that the majority of heavy metals carried by microplastics were derived from inherent load.

  20. Fabrication of micro-nano composite textured surface for slurry sawn mc-Si wafers cell

    Science.gov (United States)

    Niu, Y. C.; liu, Z.; Ren, X. K.; Liu, X. J.; Liu, H. T.; Jiang, Y. S.

    2017-01-01

    In order to enhance the PV efficiency of the cell made from slurry sawn (SS) mc-Si wafers, using a Ag-assisted electroless etching (AgNO3+HF+H2O2) combined with an auxiliary etching (HF+HNO3) the RENA textured SS mc-Si wafers (called as RENA wafers) were further textured (nano pores were formed on the original micro pits) to change into micro-nano composite textured wafers (called as MN-RENA wafers). The solar cells made from the MN-RENA wafers had a better PV efficiency than that of RENA wafers. This is mainly attributed to the higher light-trapping of the micro-nano composite texture. The nano size texture enhanced the light-trap of wafer surface and, at the same time, the micro size texture maintained the light-trap uniformity of different gains of RENA wafer. However, there still exist a potential for optimization, such as, the SiNx passviation coating should be improved to be deposited more uniformly in order to passivate the bottom of pits better and to reduce the reflectance of the obtuse tips of pits.

  1. Surface Texturing-Plasma Nitriding Duplex Treatment for Improving Tribological Performance of AISI 316 Stainless Steel

    Directory of Open Access Journals (Sweden)

    Naiming Lin

    2016-10-01

    Full Text Available Surface texturing-plasma nitriding duplex treatment was conducted on AISI 316 stainless steel to improve its tribological performance. Tribological behaviors of ground 316 substrates, plasma-nitrided 316 (PN-316, surface-textured 316 (ST-316, and duplex-treated 316 (DT-316 in air and under grease lubrication were investigated using a pin-on-disc rotary tribometer against counterparts of high carbon chromium bearing steel GCr15 and silicon nitride Si3N4 balls. The variations in friction coefficient, mass loss, and worn trace morphology of the tested samples were systemically investigated and analyzed. The results showed that a textured surface was formed on 316 after electrochemical processing in a 15 wt % NaCl solution. Grooves and dimples were found on the textured surface. As plasma nitriding was conducted on a 316 substrate and ST-316, continuous and uniform nitriding layers were successfully fabricated on the surfaces of the 316 substrate and ST-316. Both of the obtained nitriding layers presented thickness values of more than 30 μm. The nitriding layers were composed of iron nitrides and chromium nitride. The 316 substrate and ST-316 received improved surface hardness after plasma nitriding. When the tribological tests were carried out under dry sliding and grease lubrication conditions, the tested samples showed different tribological behaviors. As expected, the DT-316 samples revealed the most promising tribological properties, reflected by the lowest mass loss and worn morphologies. The DT-316 received the slightest damage, and its excellent tribological performance was attributed to the following aspects: firstly, the nitriding layer had high surface hardness; secondly, the surface texture was able to capture wear debris, store up grease, and then provide continuous lubrication.

  2. Surface Texturing-Plasma Nitriding Duplex Treatment for Improving Tribological Performance of AISI 316 Stainless Steel.

    Science.gov (United States)

    Lin, Naiming; Liu, Qiang; Zou, Jiaojuan; Guo, Junwen; Li, Dali; Yuan, Shuo; Ma, Yong; Wang, Zhenxia; Wang, Zhihua; Tang, Bin

    2016-10-27

    Surface texturing-plasma nitriding duplex treatment was conducted on AISI 316 stainless steel to improve its tribological performance. Tribological behaviors of ground 316 substrates, plasma-nitrided 316 (PN-316), surface-textured 316 (ST-316), and duplex-treated 316 (DT-316) in air and under grease lubrication were investigated using a pin-on-disc rotary tribometer against counterparts of high carbon chromium bearing steel GCr15 and silicon nitride Si₃N₄ balls. The variations in friction coefficient, mass loss, and worn trace morphology of the tested samples were systemically investigated and analyzed. The results showed that a textured surface was formed on 316 after electrochemical processing in a 15 wt % NaCl solution. Grooves and dimples were found on the textured surface. As plasma nitriding was conducted on a 316 substrate and ST-316, continuous and uniform nitriding layers were successfully fabricated on the surfaces of the 316 substrate and ST-316. Both of the obtained nitriding layers presented thickness values of more than 30 μm. The nitriding layers were composed of iron nitrides and chromium nitride. The 316 substrate and ST-316 received improved surface hardness after plasma nitriding. When the tribological tests were carried out under dry sliding and grease lubrication conditions, the tested samples showed different tribological behaviors. As expected, the DT-316 samples revealed the most promising tribological properties, reflected by the lowest mass loss and worn morphologies. The DT-316 received the slightest damage, and its excellent tribological performance was attributed to the following aspects: firstly, the nitriding layer had high surface hardness; secondly, the surface texture was able to capture wear debris, store up grease, and then provide continuous lubrication.

  3. Synthesis and texturization processes of (super)-hydrophobic fluorinated surfaces by atmospheric plasma

    CERN Document Server

    Hubert, Julie; Dufour, Thierry; Vandencasteele, Nicolas; Reniers, François; Viville, Pascal; Lazzaroni, Roberto; Raes, M; Terryn, Herman

    2016-01-01

    The synthesis and texturization processes of fluorinated surfaces by means of atmospheric plasma are investigated and presented through an integrated study of both the plasma phase and the resulting material surface. Three methods enhancing the surface hydrophobicity up to the production of super-hydrophobic surfaces are evaluated: (i) the modification of a polytetrafluoroethylene (PTFE) surface, (ii) the plasma deposition of fluorinated coatings and (iii) the incorporation of nanoparticles into those fluorinated films. In all the approaches, the nature of the plasma gas appears to be a crucial parameter for the desired property. Although a higher etching of the PTFE surface can be obtained with a pure helium plasma, the texturization can only be created if O2 is added to the plasma, which simultaneously decreases the total etching. The deposition of CxFy films by a dielectric barrier discharge leads to hydrophobic coatings with water contact angles (WCAs) of 115{\\textdegree}, but only the filamentary argon d...

  4. Automated Facial Expression Recognition Using Gradient-Based Ternary Texture Patterns

    Directory of Open Access Journals (Sweden)

    Faisal Ahmed

    2013-01-01

    Full Text Available Recognition of human expression from facial image is an interesting research area, which has received increasing attention in the recent years. A robust and effective facial feature descriptor is the key to designing a successful expression recognition system. Although much progress has been made, deriving a face feature descriptor that can perform consistently under changing environment is still a difficult and challenging task. In this paper, we present the gradient local ternary pattern (GLTP—a discriminative local texture feature for representing facial expression. The proposed GLTP operator encodes the local texture of an image by computing the gradient magnitudes of the local neighborhood and quantizing those values in three discrimination levels. The location and occurrence information of the resulting micropatterns is then used as the face feature descriptor. The performance of the proposed method has been evaluated for the person-independent face expression recognition task. Experiments with prototypic expression images from the Cohn-Kanade (CK face expression database validate that the GLTP feature descriptor can effectively encode the facial texture and thus achieves improved recognition performance than some well-known appearance-based facial features.

  5. Multi-scale microstructural characterization of micro-textured Ti-6Al-4V surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Soboyejo, W.O.; Mercer, C.; Allameh, S.; Nemetski, B. [Princeton Materials Inst., NJ (United States). Dept. of Mechanical and Aerospace Engineering; Marcantonio, N. [Brown Univ., Providence, RI (United States). Div. of Engineering; Ricci, J.L. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). Dept. of Orthodontics

    2001-07-01

    This paper presents the results of a multi-scale microstructural characterization of micro-textured Ti-6Al-4V surfaces that are used in biomedical implants. The hierarchies of substructural and microstructural features associated with laser micro-texturing, mechanical polishing and surface blasting with alumina pellets are elucidated via atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and optical microscopy (OM). The nano-scale roughness profiles for the different surface textures are characterized via AFM. Sub-micron precipitates and dislocation substructures associated with wrought processing and laser processing are revealed by TEM. OM and SEM micro- and mesoscale images of the groove structures and then described before discussing the implications of the result for the optimization of laser processing schemes. The implications of the results are examined for the fabrication of micro-textured surfaces that will facilitate the self organization of proteins, and the attachment of mammalian cells to the Ti-6Al-4V surfaces in biomedical implants. (orig.)

  6. Fabrication of Micro/Nano-textured Titanium Alloy Implant Surface and Its Inlfuence on Hydroxyapatite Coatings

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rui; WAN Yi; AI Xing; MEN Bo; WANG Teng; LIU Zhanqiang; ZHANG Dong

    2016-01-01

    We put forward a protocol combining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant. Firstly, the operational parameters of the laser were optimized to obtain an optimum current. Secondly, the laser with the optimum operational parameters was used to fabricate micro pits. Thirdly, multiple acid etching was used to clean the clinkers of micro pits and generate submicron and nanoscale structures. Finally, the bioactivity of the samples was measured in a simulated body lfuid. The results showed that the micropits with a diameter of 150 μm and depth of 50 μm were built successfully with the optimized working current of 13 A. In addition, submicron and nanoscale structures, with 0.5-2 μm microgrooves and 10-20 nm nanopits, were superimposed on micro pits surface by multiple acid etching. There was thick and dense HA coating only observed on the multiscale micro/nano-textured surface compared with polished and micro-textured surface. This indicated that the multiscale micro/nano-texture surface showed better ability toward HA formation, which increased the bioactivity of implants.

  7. Roughness analysis for textured surfaces over several orders of magnitudes

    Energy Technology Data Exchange (ETDEWEB)

    Vepsäläinen, Laura, E-mail: laura.vepsalainen@uef.fi [Department of Chemistry, University of Eastern Finland, Joensuu Campus, P.O. Box 111, FI-80101 Joensuu (Finland); Stenberg, Petri, E-mail: petri.stenberg@uef.fi [Department of Physics and Mathematics, University of Eastern Finland, Joensuu Campus, P.O. Box 111, FI-80101 Joensuu (Finland); Pääkkönen, Pertti, E-mail: pertti.paakkonen@uef.fi [Department of Physics and Mathematics, University of Eastern Finland, Joensuu Campus, P.O. Box 111, FI-80101 Joensuu (Finland); Kuittinen, Markku, E-mail: markku.kuittinen@uef.fi [Department of Physics and Mathematics, University of Eastern Finland, Joensuu Campus, P.O. Box 111, FI-80101 Joensuu (Finland); Suvanto, Mika, E-mail: mika.suvanto@uef.fi [Department of Chemistry, University of Eastern Finland, Joensuu Campus, P.O. Box 111, FI-80101 Joensuu (Finland); Pakkanen, Tapani A., E-mail: tapani.pakkanen@uef.fi [Department of Chemistry, University of Eastern Finland, Joensuu Campus, P.O. Box 111, FI-80101 Joensuu (Finland)

    2013-11-01

    Multiscale structured surfaces have roughness distributions at various spatial frequencies that affect surface properties of materials. A recently developed filtered power spectral density (FPSD) method for surface roughness characterization was generalized to comprise structures from micro- to nanoscale. Furthermore, a uniform analysis method for micro- and nanoscale characterization over five orders of magnitudes was found by combining optical profilometry data, at the microscale level and atomic force microscopy data, at the nanoscale level. The FPSD method was also combined with structure simulation for multiscales, thus the roughness distributions can be designed and studied without the fabrication of structures. Furthermore, the FPSD simulation offers a design tool for structure–property correlations.

  8. Surface Texturing Investigated for a High Solar Absorptance Low Infrared Emittance Solar Collector

    Science.gov (United States)

    Jaworske, Donald A.

    2001-01-01

    The objective of this work was to design, build, and vacuum test a high solar absorptance, low infrared emittance solar collector for heat engine and thermal switching applications. Mini-satellites proposed by the Applied Physics Laboratory for operation in environments that are subject to radiation threat may utilize a heat engine for power and a thermal bus for thermal control. To achieve this goal, a surface having high solar absorptance and low infrared emittance is needed. At the NASA Glenn Research Center, one concept being pursued to achieve this goal is texturing high thermal conductivity graphite epoxy composites using a directed atomic oxygen beam and then coating the textured surface with a reflective metallic coating. Coupons were successfully textured, coated, and evaluated. A variety of texturing conditions were explored, and textures were documented by scanning electron microscopy. Copper, gold, silver, iridium, and aluminum coatings were applied, and the highest solar absorptance to infrared emittance ratio was found to be 1.3. A full-sized solar collector was manufactured with this ratio, and the amount of heat collected was observed using an Inconel calorimeter installed in a bench-top vacuum chamber equipped with a solar simulator. Results to date indicate good heat flow through the system, with 9 W of heat flow measured by the calorimeter.

  9. Patterned nonadhesive surfaces: superhydrophobicity and wetting regime transitions.

    Science.gov (United States)

    Nosonovsky, Michael; Bhushan, Bharat

    2008-02-19

    Nonadhesive and water-repellent surfaces are required for many tribological applications. We study mechanisms of wetting of patterned superhydrophobic Si surfaces, including the transition between various wetting regimes during microdroplet evaporation in environmental scanning electron microscopy (ESEM) and for contact angle and contact angle hysteresis measurements. Wetting involves interactions at different scale levels: macroscale (water droplet size), microscale (surface texture size), and nanoscale (molecular size). We propose a generalized formulation of the Wenzel and Cassie equations that is consistent with the broad range of experimental data. We show that the contact angle hysteresis involves two different mechanisms and how the transition from the metastable partially wetted (Cassie) state to the homogeneously wetted (Wenzel) state depends upon droplet size and surface pattern parameters.

  10. Simulating the Effect of Modulated Tool-Path Chip Breaking On Surface Texture and Chip Length

    Energy Technology Data Exchange (ETDEWEB)

    Smith, K.S.; McFarland, J.T.; Tursky, D. A.; Assaid, T. S.; Barkman, W. E.; Babelay, Jr., E. F.

    2010-04-30

    One method for creating broken chips in turning processes involves oscillating the cutting tool in the feed direction utilizing the CNC machine axes. The University of North Carolina at Charlotte and the Y-12 National Security Complex have developed and are refining a method to reliably control surface finish and chip length based on a particular machine's dynamic performance. Using computer simulations it is possible to combine the motion of the machine axes with the geometry of the cutting tool to predict the surface characteristics and map the surface texture for a wide range of oscillation parameters. These data allow the selection of oscillation parameters to simultaneously ensure broken chips and acceptable surface characteristics. This paper describes the machine dynamic testing and characterization activities as well as the computational method used for evaluating and predicting chip length and surface texture.

  11. Optical stent inspection of surface texture and coating thickness

    Science.gov (United States)

    Bermudez, Carlos; Laguarta, Ferran; Cadevall, Cristina; Matilla, Aitor; Ibañez, Sergi; Artigas, Roger

    2017-02-01

    Stent quality control is a critical process. Coronary stents have to be inspected 100% so no defective stent is implanted into a human body. We have developed a high numerical aperture optical stent inspection system able to acquire both 2D and 3D images. Combining a rotational stage, an area camera with line-scan capability and a triple illumination arrangement, unrolled sections of the outer, inner, and sidewalls surfaces are obtained with high resolution. During stent inspection, surface roughness and coating thickness uniformity is of high interest. Due to the non-planar shape of the surface of the stents, the thickness values of the coating need to be corrected with the 3D surface local slopes. A theoretical model and a simulation are proposed, and a measurement with white light interferometry is shown. Confocal and spectroscopic reflectometry showed to be limited in this application due to stent surface roughness. Due to the high numerical aperture of the optical system, only certain parts of the stent are in focus, which is a problem for defect detection, specifically on the sidewalls. In order to obtain fully focused 2D images, an extended depth of field algorithm has been implemented. A comparison between pixel variance and Laplacian filtering is shown. To recover the stack image, two different methods are proposed: maximum projection and weighted intensity. Finally, we also discuss the implementation of the processing algorithms in both the CPU and GPU, targeting real-time 2-Million pixel image acquisition at 50 frames per second.

  12. Relation between light trapping and surface topography of plasma textured crystalline silicon wafers

    NARCIS (Netherlands)

    Souren, F. M. M.; Rentsch, J.; M. C. M. van de Sanden,

    2015-01-01

    Currently, in the photovoltaic industry, wet chemical etching technologies are used for saw damage removal and surface texturing. Alternative to wet chemical etching is plasma etching. However, as for example, the linear microwave plasma technique, developed by Roth&Rau, has not been implemented

  13. Relation between light trapping and surface topography of plasma textured crystalline silicon wafers

    NARCIS (Netherlands)

    Souren, F. M. M.; Rentsch, J.; M. C. M. van de Sanden,

    2015-01-01

    Currently, in the photovoltaic industry, wet chemical etching technologies are used for saw damage removal and surface texturing. Alternative to wet chemical etching is plasma etching. However, as for example, the linear microwave plasma technique, developed by Roth&Rau, has not been implemented

  14. Temporal and spatial evolution characteristics of gas-liquid two-phase flow pattern based on image texture spectrum descriptor

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xi-guo; JIN Ning-de; WANG Zhen-ya; ZHANG Wen-yin

    2009-01-01

    The dynamic image information of typical gas-liquid two-phase flow patterns in vertical upward pipe is captured by a high-speed dynamic camera. The texture spectrum descriptor is used to describe the texture characteristics of the processed images whose content is represented in the form of texture spectrum histogram, and four time-varying characteristic param-eter indexes which represent image texture structure of different flow patterns are extracted. The study results show that the amplitude fluctuation of texture characteristic parameter indexes of bubble flow is lowest and shows very random complex dynamic behavior; the amplitude fluctuation of slug flow is higher and shows intermittent motion behavior between gas slug and liquid slug, and the amplitude fluctuation of churn flow is the highest and shows better periodicity; the amplitude fluctuation of bubble-slug flow is from low to high and oscillating frequence is higher than that of slug flow, and includes the features of both slug flow and bubble flow; the slug-churn flow loses the periodicity of slug flow and churn flow, and the amplitude fluctuation is high. The results indicate that the image texture characteristic parameter indexes of different flow pattern can reflect the flow characteristics of gas-liquid two-phase flow, which provides a new approach to tmderstand the temporal and spatial evolution of flow pattern dynamics.

  15. Random Surface Texturing of Silicon Dioxide Using Gold Agglomerates

    Science.gov (United States)

    2016-07-01

    cells work by converting sunlight (electromagnetic radiation ) into electricity. Photon absorption needs to occur inside the solar cell’s active...underneath. SEM and AFM were the primary characterization techniques used to evaluate the resulting surfaces, before and after etching, and after

  16. Surface texturing of sialon ceramic by femtosecond pulsed laser

    CSIR Research Space (South Africa)

    Tshabalala, Lerato C

    2017-01-01

    Full Text Available AlONSi(sub3)N(sub4) ceramic using the Ti: Sapphire Femtosecond laser system was investigated. Parametric analysis was conducted using surface drilling, unidirectional and cross-hatching machining procedures performed on the substrate at a varied power...

  17. Mean shift texture surface detection based on WT and COM feature image selection

    Institute of Scientific and Technical Information of China (English)

    HAN Yan-fang; SHI Peng-fei

    2006-01-01

    Mean shift is a widely used clustering algorithm in image segmentation. However, the segmenting results are not so good as expected when dealing with the texture surface due to the influence of the textures. Therefore, an approach based on wavelet transform (WT), co-occurrence matrix (COM) and mean shift is proposed in this paper. First, WT and COM are employed to extract the optimal resolution approximation of the original image as feature image. Then, mean shift is successfully used to obtain better detection results. Finally, experiments are done to show this approach is effective.

  18. A Study of Hand Back Skin Texture Patterns for Personal Identification and Gender Classification

    Directory of Open Access Journals (Sweden)

    Jin Xie

    2012-06-01

    Full Text Available Human hand back skin texture (HBST is often consistent for a person and distinctive from person to person. In this paper, we study the HBST pattern recognition problem with applications to personal identification and gender classification. A specially designed system is developed to capture HBST images, and an HBST image database was established, which consists of 1,920 images from 80 persons (160 hands. An efficient texton learning based method is then presented to classify the HBST patterns. First, textons are learned in the space of filter bank responses from a set of training images using the -minimization based sparse representation (SR technique. Then, under the SR framework, we represent the feature vector at each pixel over the learned dictionary to construct a representation coefficient histogram. Finally, the coefficient histogram is used as skin texture feature for classification. Experiments on personal identification and gender classification are performed by using the established HBST database. The results show that HBST can be used to assist human identification and gender classification.

  19. Mechanical interlocking of cotton fibers on slightly textured surfaces of metallic cylinders

    Science.gov (United States)

    Zhang, Youqiang; Tian, Yu; Meng, Yonggang

    2016-05-01

    Mechanical interlocking is widely applied in industry and general lives of human beings. In this work, we realized the control of locking or sliding states of cotton fibers on the metal surfaces with slightly different textures through traditional machining. Three types of sliding states, i.e., locking, one-way sliding, and two-way sliding have been achieved. It is found that the locking or sliding of the cotton fibers on the metallic cylinder depends on the friction coefficient and the ratio of cotton fiber diameter, 2r, to the height of the rough peaks, h, of metal surfaces. When the critical ratio h/r exceeds 1, the cotton fibers could tightly attach to the metallic surface through mechanical interlocking. This work provided a convenient and universal method for the control of interlocking or sliding of fiber-based materials on textured surfaces.

  20. Enhanced quantum efficiency of photoelectron emission, through surface textured metal electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Anna; Bandaru, Prabhakar R., E-mail: pbandaru@ucsd.edu [Program in Materials Science, Department of Mechanical Engineering, University of California, San Diego, La Jolla, California, 92130 (United States); Moody, Nathan A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-03-15

    It is predicted that the quantum efficiency (QE) of photoelectron emission from metals may be enhanced, possibly by an order of magnitude, through optimized surface texture. Through extensive computational simulations, it is shown that the absorption enhancement in select surface groove geometries may be a dominant contributor to enhanced QE and corresponds to localized Fabry–Perot resonances. The inadequacy of extant analytical models in predicting the QE increase, and suggestions for further improvement, are discussed.

  1. Fast wettability transition from hydrophilic to superhydrophobic laser-textured stainless steel surfaces under low-temperature annealing

    Science.gov (United States)

    Ngo, Chi-Vinh; Chun, Doo-Man

    2017-07-01

    Recently, the fabrication of superhydrophobic metallic surfaces by means of pulsed laser texturing has been developed. After laser texturing, samples are typically chemically coated or aged in ambient air for a relatively long time of several weeks to achieve superhydrophobicity. To accelerate the wettability transition from hydrophilicity to superhydrophobicity without the use of additional chemical treatment, a simple annealing post process has been developed. In the present work, grid patterns were first fabricated on stainless steel by a nanosecond pulsed laser, then an additional low-temperature annealing post process at 100 °C was applied. The effect of 100-500 μm step size of the textured grid upon the wettability transition time was also investigated. The proposed post process reduced the transition time from a couple of months to within several hours. All samples showed superhydrophobicity with contact angles greater than 160° and sliding angles smaller than 10° except samples with 500 μm step size, and could be applied in several potential applications such as self-cleaning and control of water adhesion.

  2. Holographic microscopy and microfluidics platform for measuring wall stress and 3D flow over surfaces textured by micro-pillars

    Science.gov (United States)

    Bocanegra Evans, Humberto; Gorumlu, Serdar; Aksak, Burak; Castillo, Luciano; Sheng, Jian

    2016-06-01

    Understanding how fluid flow interacts with micro-textured surfaces is crucial for a broad range of key biological processes and engineering applications including particle dispersion, pathogenic infections, and drag manipulation by surface topology. We use high-speed digital holographic microscopy (DHM) in combination with a correlation based de-noising algorithm to overcome the optical interference generated by surface roughness and to capture a large number of 3D particle trajectories in a microfluidic channel with one surface patterned with micropillars. It allows us to obtain a 3D ensembled velocity field with an uncertainty of 0.06% and 2D wall shear stress distribution at the resolution of ~65 μPa. Contrary to laminar flow in most microfluidics, we find that the flow is three-dimensional and complex for the textured microchannel. While the micropillars affect the velocity flow field locally, their presence is felt globally in terms of wall shear stresses at the channel walls. These findings imply that micro-scale mixing and wall stress sensing/manipulation can be achieved through hydro-dynamically smooth but topologically rough micropillars.

  3. Effect of droplet size on wetting behavior on laser textured SiC surface

    Science.gov (United States)

    Wang, Rong; Bai, Shaoxian

    2015-10-01

    Effect of droplet size on wetting behavior on laser textured SiC surface was studied in this work. The micro-square-convex surface was processed on smooth surface with intrisinc contact angle 101°. Then contact angles were measured on both smooth and textured surface by sessile drop method using deionized water with different droplet volume. It was found that there was significant droplet size effect on wetting behaviors for the textured SiC surface. Contact angles on smooth surface kept stable for different water droplet volume with a variation amplitude 13°. However, contact angles increased significantly from 42.25° to 131.25° with increasing droplet volume from 0.001 μL to 1 μL, then remained unchanged when the droplet volume exceeds 1 μL. The correlation analysis shows that contact angles increase with the increasing ratio of base diameter and groove width, then keep stable when the ratio exceeds 25, which explains the wetting behavior for different droplet volume.

  4. Modeling broad-scale patterns of avian species richness across the Midwestern United States with measures of satellite image texture

    Science.gov (United States)

    Patrick D. Culbert; Volker C. Radeloff; Veronique St-Louis; Curtis H. Flather; Chadwick D. Rittenhouse; Thomas P. Albright; Anna M. Pidgeon

    2012-01-01

    Avian biodiversity is threatened, and in order to prioritize limited conservation resources and conduct effective conservation planning a better understanding of avian species richness patterns is needed. The use of image texture measures, as a proxy for the spatial structure of land cover and vegetation, has proven useful in explaining patterns of avian abundance and...

  5. Surface fractal dimensions and textural properties of mesoporous alkaline-earth hydroxyapatites

    Energy Technology Data Exchange (ETDEWEB)

    Vilchis-Granados, J. [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico); Granados-Correa, F., E-mail: francisco.granados@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Barrera-Díaz, C.E. [Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico)

    2013-08-15

    This work examines the surface fractal dimensions (D{sub f}) and textural properties of three different alkaline-earth hydroxyapatites. Calcium, strontium and barium hydroxyapatite compounds were successfully synthesized via chemical precipitation method and characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and N{sub 2}-physisorption measurements. Surface fractal dimensions were determined using single N{sub 2}-adsorption/desorption isotherms method to quantify the irregular surface of as-prepared compounds. The obtained materials were also characterized through their surface hydroxyl group content, determined by the mass titration method. It was found that the D{sub f} values for the three materials covered the range of 0.77 ± 0.04–2.33 ± 0.11; these results indicated that the materials tend to have smooth surfaces, except the irregular surface of barium hydroxyapatite. Moreover, regarding the synthesized calcium hydroxyapatite exhibited better textural properties compared with the synthesized strontium and barium hydroxyapatites for adsorbent purposes. However, barium hydroxyapatite shows irregular surface, indicating a high population of active sites across the surface, in comparison with the others studied hydroxyapatites. Finally, the results showed a linear correlation between the surface hydroxyl group content at the external surface of materials and their surface fractal dimensions.

  6. Surface morphology of highly ordered nanotube formed and laser textured beta titanium alloys.

    Science.gov (United States)

    Kim, Jae-Un; Jeong, Yong-Hoon; Choe, Han-Cheol

    2013-03-01

    The aim of the present study is to produce and characterize a well-controlled surface texture on Ti-35Nb-xHf alloys to promote osseointegration. Ti-35Nb-xHf (x = 0, 3, 7 and 15 wt.%) alloys were prepared by arc melting and heat treated for 12 hr at 1000 degrees C in an argon atmosphere and then water quenching. For surface texturing, an amplified Ti: sapphire laser system was used for generating 184 femtosecond (FS, 10(-15) sec) laser pulses with the pulse energy over 30 mJ at a 1 kHz repetition rate with a central wavelength of 800 nm. The nanotube formation was achieved by anodizing a Ti-35Nb-xHf alloy in H3PO4 electrolytes containing 0.8 wt.% NaF at room temperature. The surface morphology of nano/micro structure will enhance osseointegration and cell adhesion.

  7. Effect of fingerprints orientation on skin vibrations during tactile exploration of textured surfaces

    CERN Document Server

    Prevost, Alexis; Debrégeas, Georges

    2009-01-01

    In humans, the tactile perception of fine textures is mediated by skin vibrations when scanning the surface with the fingertip. These vibrations are encoded by specific mechanoreceptors, Pacinian corpuscules (PCs), located about 2 mm below the skin surface. In a recent article, we performed experiments using a biomimetic sensor which suggest that fingerprints (epidermal ridges) may play an important role in shaping the subcutaneous stress vibrations in a way which facilitates their processing by the PC channel. Here we further test this hypothesis by directly recording the modulations of the fingerpad/substrate friction force induced by scanning an actual fingertip across a textured surface. When the fingerprints are oriented perpendicular to the scanning direction, the spectrum of these modulations shows a pronounced maximum around the frequency v/lambda, where v is the scanning velocity and lambda the fingerprints period. This simple biomechanical result confirms the relevance of our previous finding for hu...

  8. Effect of fingerprints orientation on skin vibrations during tactile exploration of textured surfaces.

    Science.gov (United States)

    Prevost, Alexis; Scheibert, Julien; Debrégeas, Georges

    2009-09-01

    In humans, the tactile perception of fine textures is mediated by skin vibrations when scanning the surface with the fingertip. These vibrations are encoded by specific mechanoreceptors, Pacinian corpuscules (PCs), located about 2 mm below the skin surface. In a recent article, we performed experiments using a biomimetic sensor which suggest that fingerprints (epidermal ridges) may play an important role in shaping the subcutaneous stress vibrations in a way which facilitates their processing by the PC channel. Here we further test this hypothesis by directly recording the modulations of the fingerpad/substrate friction force induced by scanning an actual fingertip across a textured surface. When the fingerprints are oriented perpendicular to the scanning direction, the spectrum of these modulations shows a pronounced maximum around the frequency v/lambda, where v is the scanning velocity and lambda the fingerprints period. This simple biomechanical result confirms the relevance of our previous finding for human touch.

  9. Molecular kinetic theory of boundary slip on textured surfaces by molecular dynamics simulations

    Science.gov (United States)

    Wang, LiYa; Wang, FengChao; Yang, FuQian; Wu, HengAn

    2014-11-01

    A theoretical model extended from the Frenkel-Eyring molecular kinetic theory (MKT) was applied to describe the boundary slip on textured surfaces. The concept of the equivalent depth of potential well was adopted to characterize the solid-liquid interactions on the textured surfaces. The slip behaviors on both chemically and topographically textured surfaces were investigated using molecular dynamics (MD) simulations. The extended MKT slip model is validated by our MD simulations under various situations, by constructing different complex surfaces and varying the surface wettability as well as the shear stress exerted on the liquid. This slip model can provide more comprehensive understanding of the liquid flow on atomic scale by considering the influence of the solid-liquid interactions and the applied shear stress on the nano-flow. Moreover, the slip velocity shear-rate dependence can be predicted using this slip model, since the nonlinear increase of the slip velocity under high shear stress can be approximated by a hyperbolic sine function.

  10. Molecular kinetic theory of boundary slip on textured surfaces by molecular dynamics simulations

    Institute of Scientific and Technical Information of China (English)

    WANG LiYa; WANG FengChao; YANG FuQian; WU HengAn

    2014-01-01

    A theoretical model extended from the Frenkel-Eyring molecular kinetic theory (MKT) was applied to describe the boundary slip on textured surfaces.The concept of the equivalent depth of potential well was adopted to characterize the solid-liquid interactions on the textured surfaces.The slip behaviors on both chemically and topographically textured surfaces were investigated using molecular dynamics (MD) simulations.The extended MKT slip model is validated by our MD simulations under various situations,by constructing different complex surfaces and varying the surface wettability as well as the shear stress exerted on the liquid.This slip model can provide more comprehensive understanding of the liquid flow on atomic scale by considering the influence of the solid-liquid interactions and the applied shear stress on the nano-flow.Moreover,the slip velocity shear-rate dependence can be predicted using this slip model,since the nonlinear increase of the slip velocity under high shear stress can be approximated by a hyperbolic sine function.

  11. Influence of citric acid on the surface texture of glass ionomer restorative materials

    Directory of Open Access Journals (Sweden)

    Dappili SwamiRanga Reddy

    2014-01-01

    Full Text Available Aim: This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Materials and Methods: Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7. Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, ΅m of each specimen was measured using a surface profilometer (Taylor & Habson, UK. Data was analyzed using one-way analysis of variance (ANOVA and Tukey′s HSD test at a significance level of 0.05. Results: The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. Conclusion: The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of

  12. Study on cavitation effect of mechanical seals with laser-textured porous surface

    Science.gov (United States)

    Liu, T.; Chen, H. l.; Liu, Y. H.; Wang, Q.; Liu, Z. B.; Hou, D. H.

    2012-11-01

    Study on the mechanisms underlying generation of hydrodynamic pressure effect associated with laser-textured porous surface on mechanical seal, is the key to seal and lubricant properties. The theory model of mechanical seals with laser-textured porous surface (LES-MS) based on cavitation model was established. The LST-MS was calculated and analyzed by using Fluent software with full cavitation model and non-cavitation model and film thickness was predicted by the dynamic mesh technique. The results indicate that the effect of hydrodynamic pressure and cavitation are the important reasons to generate liquid film opening force on LST-MS; Cavitation effect can enhance hydrodynamic pressure effect of LST-MS; The thickness of liquid film could be well predicted with the method of dynamic mesh technique on Fluent and it becomes larger as the increasing of shaft speed and the decreasing of pressure.

  13. Analysis of Pyramidal Surface Texturization of Silicon Solar Cells by Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Hsiao-Yen Chung

    2008-01-01

    Full Text Available The purpose of this paper is to explore the relations between surface texturization and absorptance of multicrystalline silicon solar cells by a simple new model, based on the classic molecular (MD dynamics simulation, alternative to complex electron-photon interactions to analyze the surface texturization of solar cells. In this study, the large tilted angle leads to the lower efficiency of solar cell. To consider the effect of incident angle, a range of high efficiency exists due to the increasing probability of second reflection. Furthermore, the azimuth angle of incident light also affects the efficiency of solar cells. Our results agree well with previous studies. This MD model can potentially be used to predict the efficiency promotion in any optical reflection-absorption cases.

  14. A NOVEL WRAPPING CURVELET TRANSFORMATION BASED ANGULAR TEXTURE PATTERN (WCTATP EXTRACTION METHOD FOR WEED IDENTIFICATION

    Directory of Open Access Journals (Sweden)

    D. Ashok Kumar

    2016-02-01

    Full Text Available Apparently weed is a major menace in crop production as it competes with crop for nutrients, moisture, space and light which resulting in poor growth and development of the crop and finally yield. Yield loss accounts for even more than 70% when crops are frown under unweeded condition with severe weed infestation. Weed management is the most significant process in the agricultural applications to improve the crop productivity rate and reduce the herbicide application cost. Existing weed detection techniques does not yield better performance due to the complex background, illumination variation and crop and weed overlapping in the agricultural field image. Hence, there arises a need for the development of effective weed identification technique. To overcome this drawback, this paper proposes a novel Wrapping Curvelet Transformation Based Angular Texture Pattern Extraction Method (WCTATP for weed identification. In our proposed work, Global Histogram Equalization (GHE is used improve the quality of the image and Adaptive Median Filter (AMF is used for filtering the impulse noise from the image. Plant image identification is performed using green pixel extraction and k-means clustering. Wrapping Curvelet transform is applied to the plant image. Feature extraction is performed to extract the angular texture pattern of the plant image. Particle Swarm Optimization (PSO based Differential Evolution Feature Selection (DEFS approach is applied to select the optimal features. Then, the selected features are learned and passed through an RVM based classifier to find out the weed. Edge detection and contouring is performed to identify the weed in the plant image. The Fuzzy rule-based approach is applied to detect the low, medium and high levels of the weed patchiness. From the experimental results, it is clearly observed that the accuracy of the proposed approach is higher than the existing Support Vector Machine (SVM based approaches. The proposed approach

  15. An international comparison of surface texture parameters quantification on polymer artefacts using optical instruments

    DEFF Research Database (Denmark)

    Tosello, Guido; Haitjema, H.; Leach, R.K.

    2016-01-01

    scanning interferometers) from thirteen research laboratories worldwide. Results demonstrated that: (i)Agreement among different instruments could be achieved to a limited extent; (ii) standardisedguidelines for uncertainty evaluation of areal surface parameters are needed for users; (iii......An international comparison of optical instruments measuring polymer surfaces with arithmetic mean height values in the sub-micrometre range has been carried out. The comparison involved sixteen optical surface texture instruments (focus variation instruments, confocal microscopes and coherent......) it is essentialthat the performance characteristics (and especially the spatial frequency response) of an instrument isunderstood prior to a measurement....

  16. Influence of Conditioned Surface Textures on Plain Journal Bearing Performance Working on HL Conditions

    OpenAIRE

    Vélez-Restrepo J.M.; Toro-Botero F.M.; Suárez-Bustamante F.A.

    2012-01-01

    As an answer to the need for reducing friction losses on bearings, dynamic seals, piston rings, cutting tools and others, a lot of work has been dedicated to mechanical systems study whose surfaces have been textured in a controlled way. Theoretical models and experimental results have shown improvements on the tribological performance of these systems regarding untextured systems, working under the same conditions. This paper presents a numerical model for getting relationships among the ope...

  17. Increasing the hydrophobicity degree of stonework by means of laser surface texturing: An application on Zimbabwe black granites

    Science.gov (United States)

    Chantada, A.; Penide, J.; Riveiro, A.; del Val, J.; Quintero, F.; Meixus, M.; Soto, R.; Lusquiños, F.; Pou, J.

    2017-10-01

    Tailoring the wetting characteristics of materials has gained much interest in applications related to surface cleaning in both industry and home. Zimbabwe black granite is a middle-to-fine-grained natural stone commonly used as countertops in kitchens and bathrooms. In this study, the laser texturing of Zimbabwe black granite surfaces is investigated with the aim to enhance its hydrophobic character, thus reducing the attachment of contaminants on the surface. Two laser sources (λ = 1064 and 532 nm) were used for this purpose. The treatment is based on the irradiation of the stone by a laser focused on the surface of the targeting sample. The influence of different laser processing parameters on the surface characteristics of granite (wettability, roughness, and chemistry) was statistically assessed. Most suitable laser processing parameters required to obtain the highest hydrophobicity degree were identified. It has been possible to identify the 532 nm laser wavelength as the most effective one to increase the hydrophobic degree of Zimbabwe black granite surface. The phenomenon governing wettability changes was found to be the surface roughness patterns, given the unaltered chemical surface composition after laser processing.

  18. Surface Patterning and Nanowire Biosensor Construction

    DEFF Research Database (Denmark)

    Iversen, Lars

    2008-01-01

    This thesis describes the preparation and characterization of three systems where surfaces of solid matter are interfaced with organic and biomolecular components, with the aim of creating (I) Patterned surfaces and (II) Functional nanowire sensor platforms for bionanotechnological applications...... assembled monolayer on gold, a technique useful for creating diverse monolayer patterns in a direct-write fashion. Addition of a second alkanethiol forms a topologically ultra flat but chemically patterned surface, which by inspection with scanning electron microscopy and atomic force microscopy revealed...

  19. Surface passivation of nano-textured fluorescent SiC by atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

    2016-01-01

    Nano-textured surfaces have played a key role in optoelectronic materials to enhance the light extraction efficiency. In this work, morphology and optical properties of nano-textured SiC covered with atomic layer deposited (ALD) TiO2 were investigated. In order to obtain a high quality surface...... for TiO2 deposition, a three-step cleaning procedure was introduced after RIE etching. The morphology of anatase TiO2 indicates that the nano-textured substrate has a much higher surface nucleated grain density than a flat substrate at the beginning of the deposition process. The corresponding...... reflectance increases with TiO2 thickness due to increased surface diffuse reflection. The passivation effect of ALD TiO2 thin film on the nano-textured fluorescent 6H-SiC sample was also investigated and a PL intensity improvement of 8.05% was obtained due to the surface passivation....

  20. The effect of laser surface texturing on the tribological performance of different Sialon ceramic phases

    Institute of Scientific and Technical Information of China (English)

    Bhupendra Joshi; Khagendra Tripathi; Gobinda Gyawali; Soo Wohn Lee

    2016-01-01

    A tribological performance was carried out on different types of hot press Sialon ceramics regarding the phases, i.e., theα-Sialon phase, theβ-Sialon phase, and theα/β-Sialon composite phase. The different phases of Sialon ceramics were analyzed by XRD patterns. For the tribological performance, the Sialon ceramics were laser textured and the starved lubrication method was applied with different dimple pitches under a load of 10 N at room temperature. The material having a dimple pitch of 200μm shows the lowest coefficient of friction. Theα/β-Sialon composite phase shows the least coefficient of friction i.e. 0.04 and 0.1 for the textured and polished (without being textured) samples, respectively. The Sialon ceramics show mild wear and therefore, the wear rate of the steel ball (mating partner) was taken into account for the wear analysis. Theα-Sialon phase having a higher hardness shows the least wear in comparison to theα/β-Sialon composite phase and theβ-Sialon phase.

  1. Long-lasting solid lubrication by CNT-coated patterned surfaces

    Science.gov (United States)

    Reinert, L.; Lasserre, F.; Gachot, C.; Grützmacher, P.; MacLucas, T.; Souza, N.; Mücklich, F.; Suarez, S.

    2017-02-01

    The use of lubricants (solid or liquid) is a well-known and suitable approach to reduce friction and wear of moving machine components. Another possibility to influence the tribological behaviour is the formation of well-defined surface topographies such as dimples, bumps or lattice-like pattern geometries by laser surface texturing. However, both methods are limited in their effect: surface textures may be gradually destroyed by plastic deformation and lubricants may be removed from the contact area, therefore no longer properly protecting the contacting surfaces. The present study focuses on the combination of both methods as an integral solution, overcoming individual limitations of each method. Multiwall carbon nanotubes (MWCNT), a known solid lubricant, are deposited onto laser surface textured samples by electrophoretic deposition. The frictional behaviour is recorded by a tribometer and resulting wear tracks are analysed by scanning electron microscopy and Raman spectroscopy in order to reveal the acting tribological mechanisms. The combined approach shows an extended, minimum fivefold longevity of the lubrication and a significantly reduced degradation of the laser textures. Raman spectroscopy proves decelerated MWCNT degradation and oxide formation in the contact. Finally, a lubricant entrapping model based on surface texturing is proposed and demonstrated.

  2. Optical design and laser ablation of surface textures: demonstrating total internal reflection

    Science.gov (United States)

    Gommans, Hans; Booij, Silvia; Pijlman, Fetze; Krijn, Marcel; de Zwart, Siebe; Sepkhanov, Ruslan; Beaumont, Dave; van der Schaft, Hans; Sanders, Rene

    2015-09-01

    In lighting applications key drivers for optical design of surface textures are integration of optical elements, the disentanglement of optical functionality and appearance and late stage configuration. We investigated excimer laser ablation as a mastering technology for micro textured surfaces, where we targeted an increase in correspondence between surface design and ablated surface for high aspect ratio structures. To achieve this we have improved the photo mask design using a heuristic algorithm that corrects for the angular dependence of the ablation process and the loss of image resolution at ablation depths that exceed the depth of field. Using this approach we have been able to demonstrate close correspondence between designed and ablated facet structures up to 75° inclination at 75 μm depth. These facet design parameters allow for total internal reflection (TIR) as a means of beam deflection which is demonstrated in a range of mono shaped cone arrays in hexagonal tessellation. BSDF analysis was used to characterize the narrow TIR deflection beams that matched the peak positions of the design down to 28° apex. In addition, a single surface TIR-Fresnel lens design with focal distance 5 mm has been manufactured using this photo mask design algorithm and beam collimation up to 12° beam angle and 32° field angle is shown. These outcomes demonstrate that the laser ablation process intrinsically yields sufficient small dispersion in structure and fillet radii for lighting applications.

  3. Invisible Surface Charge Pattern on Inorganic Electrets

    DEFF Research Database (Denmark)

    Wang, Fei; Hansen, Ole

    2013-01-01

    We propose an easy method to pattern the surface charge of ${\\rm SiO}_{2}$ electrets without patterning the dielectric layer. By eliminating the use of metal guard electrodes, both the charge efficiency and the surface charge stability in humid environments improve. We apply the concept to a vibr...

  4. Large-Scale Point-Cloud Visualization through Localized Textured Surface Reconstruction.

    Science.gov (United States)

    Arikan, Murat; Preiner, Reinhold; Scheiblauer, Claus; Jeschke, Stefan; Wimmer, Michael

    2014-09-01

    In this paper, we introduce a novel scene representation for the visualization of large-scale point clouds accompanied by a set of high-resolution photographs. Many real-world applications deal with very densely sampled point-cloud data, which are augmented with photographs that often reveal lighting variations and inaccuracies in registration. Consequently, the high-quality representation of the captured data, i.e., both point clouds and photographs together, is a challenging and time-consuming task. We propose a two-phase approach, in which the first (preprocessing) phase generates multiple overlapping surface patches and handles the problem of seamless texture generation locally for each patch. The second phase stitches these patches at render-time to produce a high-quality visualization of the data. As a result of the proposed localization of the global texturing problem, our algorithm is more than an order of magnitude faster than equivalent mesh-based texturing techniques. Furthermore, since our preprocessing phase requires only a minor fraction of the whole data set at once, we provide maximum flexibility when dealing with growing data sets.

  5. Surface texture and some properties of acrylic resins submitted to chemical polishing.

    Science.gov (United States)

    Braun, K O; Mello, J A N; Rached, R N; Del Bel Cury, A A

    2003-01-01

    The effects of chemical polishing on dental acrylic resin properties are not well clarified. This study evaluated the effect of chemical and mechanical polishing on the residual monomer release (RM), Knoop hardness (KH), transverse strength (TS) and surface texture (ST) of a heat- and self-cured acrylic resin. Four groups were formed: GI-self-cured resin/mechanical polishing; GII-self-cured resin/chemical polishing; GIII-heat-cured resin/mechanical polishing; GIV-heat-cured resin/chemical polishing. Following the polishing procedures, specimens were stored in distilled water at 37 degrees C. The KH and RM measurements were taken after 1, 2, 8 and 32 days of storage, and TS after 2, 8 and 32 days. Surface texture was observed under SEM evaluation. Results were compared statistically at a confidence level of 95%. The following conclusions were drawn: (1) regardless of the acrylic resin and the period of analysis, chemical polishing increased RM levels, reduced KH, and did not affect TS significantly; (2) water storage increased the surface hardness of GII and GIV; (3) GII and GIV showed a smooth and wavy surface under SEM evaluation.

  6. Investigation of mechanical responses to the tactile perception of surfaces with different textures using the finite element method

    Directory of Open Access Journals (Sweden)

    Wei Tang

    2016-07-01

    Full Text Available Tactile perception is essential for humans to perceive the world, and it usually results in mechanical responses from the finger. In this study, a nonlinear, viscoelastic, and multilayered finite element model of the finger was developed. The relationship between the mechanical responses within the finger and tactile perception while the finger scanned different surface textures was studied. The results showed that the sensitivity of tactile perception is affected by the peak value of von Mises stress, which is itself determined by the shape and density of a given texture. The von Mises stress varies periodically with time, and this variation depends on the periodicity of the texture. Displacement signals around Pacinian corpuscles have periodic variation. The period of displacement decreases as the density of the texture increases. The spectral centroid increases as the spacing of the texture decreases. The related mechanisms are discussed in this article.

  7. The Friction Reducing Effect of Square-Shaped Surface Textures under Lubricated Line-Contacts—An Experimental Study

    Directory of Open Access Journals (Sweden)

    Ping Lu

    2016-07-01

    Full Text Available Surface texturing has been shown to be an effective modification approach for improving tribological performance. This study examined the friction reduction effect generated by square dimples of different sizes and geometries. Dimples were fabricated on the surface of ASP2023 steel plates using femtosecond laser-assisted surface texturing techniques, and reciprocating sliding line contact tests were carried out on a Plint TE77 tribometer using a smooth 52100 bearing steel roller and textured ASP2023 steel plates. The tribological characterization of the friction properties indicated that the textured samples had significantly lowered the friction coefficient in both boundary (15% improvement and mixed lubrication regimes (13% improvement. Moreover, the high data sampling rate results indicated that the dimples work as lubricant reservoirs in the boundary lubrication regime.

  8. Femtosecond laser surface texturing of titanium as a method to reduce the adhesion of Staphylococcus aureus and biofilm formation

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Alexandre [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Elie, Anne-Marie [Bordeaux University, CBMN UMR 5248, CNRS, Bordeaux Science Agro, 1 Rue du G. de Gaulle, 33170 Gradignan (France); Plawinski, Laurent [Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Serro, Ana Paula [Instituto Superior Técnico, Universidade de Lisboa, CQE-Centro de Química Estrutural, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); Botelho do Rego, Ana Maria [Instituto Superior Técnico, Universidade de Lisboa, CQFM-Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology - IN, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); Almeida, Amélia [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Urdaci, Maria C. [Bordeaux University, CBMN UMR 5248, CNRS, Bordeaux Science Agro, 1 Rue du G. de Gaulle, 33170 Gradignan (France); Durrieu, Marie-Christine [Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Vilar, Rui, E-mail: rui.vilar@tecnico.ulisboa.pt [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

    2016-01-01

    Graphical abstract: - Highlights: • The short-term adhesion of Staphylococcus aureus onto femtosecond laser textured surfaces of titanium was investigated. • The laser textured surfaces consist of laser-induced periodic surface structures (LIPSS) and nanopillars. • The laser treatment enhances the hydrophilicity and the surface free energy of the material. • The laser treatment reduces significantly the adhesion of S. aureus and biofilm formation. • Femtosecond laser surface texturing of titanium is a simple and promising method for endowing dental and orthopedic implants with antibacterial properties. - Abstract: The aim of the present work was to investigate the possibility of using femtosecond laser surface texturing as a method to reduce the colonization of Grade 2 Titanium alloy surfaces by Staphylococcus aureus and the subsequent formation of biofilm. The laser treatments were carried out with a Yb:KYW chirped-pulse-regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. Two types of surface textures, consisting of laser-induced periodic surface structures (LIPSS) and nanopillars, were produced. The topography, chemical composition and phase constitution of these surfaces were investigated by atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction. Surface wettability was assessed by the sessile drop method using water and diiodomethane as testing liquids. The response of S. aureus put into contact with the laser treated surfaces in controlled conditions was investigated by epifluorescence microscopy and scanning electron microscopy 48 h after cell seeding. The results achieved show that the laser treatment reduces significantly the bacterial adhesion to the surface as well as biofilm formation as compared to a reference polished surfaces and suggest that femtosecond laser texturing is a simple and promising method

  9. [Effect of freezing and cooking on the texture and electrophoretic pattern of the proteins of octopus arms (Octopus vulgaris)].

    Science.gov (United States)

    Reyes, Genara; Nirchio, Mauro; Bello, Rafael; Borderías, Javier

    2014-09-01

    Texture is the most valuable feature in cephalopods. Factors that mainly affect the texture of octopus are: freezing, scalding and cooking. The aim of this study was to assess the effect of freezing, scalding and length of cooking time on the texture and electrophoretic pattern of proteins of octopus arms. Octopuses were trapped near Margarita Island and carried with ice to the laboratory where they were packed and subjected to: a) freezing at -27 degrees C or at -20 degrees C b) scalding c) cooking for 25 min, 35 min or 45 min. Shear force was determined by Kramer cell on strips of octopus arms. SDS-PAGE was done according to the Laemmli method with 12% polyacrilamide gels. A sensory evaluation of the preference of texture was carried out using a hedonic scale of 7-points and a non-trained panel. Octopus texture was not affected by freezing temperature or scalding. Frozen octopus was softer after cooking than fresh. The longer the cooking time was, the softer the octopus was. Myosin heavy chain (MHC) was not significantly affected by scalding or cooking; however large aggregates heavier than MHC, new bands and loss of resolution of the bands appeared. Myosin and paramyosin bands were more affected by freezing prior to cooking.

  10. Computer Graphics Meets Image Fusion: the Power of Texture Baking to Simultaneously Visualise 3d Surface Features and Colour

    Science.gov (United States)

    Verhoeven, G. J.

    2017-08-01

    Since a few years, structure-from-motion and multi-view stereo pipelines have become omnipresent in the cultural heritage domain. The fact that such Image-Based Modelling (IBM) approaches are capable of providing a photo-realistic texture along the threedimensional (3D) digital surface geometry is often considered a unique selling point, certainly for those cases that aim for a visually pleasing result. However, this texture can very often also obscure the underlying geometrical details of the surface, making it very hard to assess the morphological features of the digitised artefact or scene. Instead of constantly switching between the textured and untextured version of the 3D surface model, this paper presents a new method to generate a morphology-enhanced colour texture for the 3D polymesh. The presented approach tries to overcome this switching between objects visualisations by fusing the original colour texture data with a specific depiction of the surface normals. Whether applied to the original 3D surface model or a lowresolution derivative, this newly generated texture does not solely convey the colours in a proper way but also enhances the smalland large-scale spatial and morphological features that are hard or impossible to perceive in the original textured model. In addition, the technique is very useful for low-end 3D viewers, since no additional memory and computing capacity are needed to convey relief details properly. Apart from simple visualisation purposes, the textured 3D models are now also better suited for on-surface interpretative mapping and the generation of line drawings.

  11. High-resolution (SIMS) versus bulk sulfur isotope patterns of pyrite in Proterozoic microbialites with diverse mat textures

    Science.gov (United States)

    Gomes, M. L.; Fike, D. A.; Bergmann, K.; Knoll, A. H.

    2015-12-01

    Sulfur (S) isotope signatures of sedimentary pyrite preserved in marine rocks provide a rich suite of information about changes in biogeochemical cycling associated with the evolution of microbial metabolisms and oxygenation of Earth surface environments. Conventionally, these S isotope records are based on bulk rock measurements. Yet, in modern microbial mat environments, S isotope compositions of sulfide can vary by up to 40‰ over a spatial range of ~ 1 mm. Similar ranges of S isotope variability have been found in Archean pyrite grains using both Secondary Ion Mass Spectrometry and other micro-analytical techniques. These micron-scale patterns have been linked to changes in rates of microbial sulfate reduction and/or sulfide oxidation, isotopic distillation of the sulfate reservoir due to microbial sulfate reduction, and post-depositional alteration. Fine-scale mapping of S isotope compositions of pyrite can thus be used to differentiate primary environmental signals from post-depositional overprinting - improving our understanding of both. Here, we examine micron-scale S isotope patterns of pyrite in microbialites from the Mesoproterozoic-Neoproterozoic Sukhaya Tunguska Formation and Neoproterozoic Draken Formation in order to explore S isotope variability associated with different mat textures and pyrite grain morphologies. A primary goal is to link modern observations of how sulfide spatial isotope distributions reflect active microbial communities present at given depths in the mats to ancient processes driving fine-sale pyrite variability in microbialites. We find large (up to 60‰) S isotope variability within a spatial range of less than 2.5cm. The micron-scale S isotope measurements converge around the S isotope composition of pyrite extracted from bulk samples of the same microbialites. These micron-scale pyrite S isotope patterns have the potential to reveal important information about ancient biogeochemical cycling in Proterozoic mat environments

  12. TEXTURAL FRACTOGRAPHY

    Directory of Open Access Journals (Sweden)

    Hynek Lauschmann

    2011-05-01

    Full Text Available The reconstitution of the history of a fatigue process is based on the knowledge of any correspondences between the morphology of the crack surface and the velocity of the crack growth (crack growth rate - CGR. The textural fractography is oriented to mezoscopic SEM magnifications (30 to 500x. Images contain complicated textures without distinct borders. The aim is to find any characteristics of this texture, which correlate with CGR. Pre-processing of images is necessary to obtain a homogeneous texture. Three methods of textural analysis have been developed and realized as computational programs: the method based on the spectral structure of the image, the method based on a Gibbs random field (GRF model, and the method based on the idealization of light objects into a fibre process. In order to extract and analyze the fibre process, special methods - tracing fibres and a database-oriented analysis of a fibre process - have been developed.

  13. Laser scanning on road pavements: a new approach for characterizing surface texture.

    Science.gov (United States)

    Bitelli, Gabriele; Simone, Andrea; Girardi, Fabrizio; Lantieri, Claudio

    2012-01-01

    The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the "texture" appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey.

  14. Investigation of mechanism: spoof SPPs on periodically textured metal surface with pyramidal grooves

    Science.gov (United States)

    Tian, Lili; Liu, Jianlong; Zhou, Keya; Gao, Yang; Liu, Shutian

    2016-08-01

    In microwave and terahertz frequency band, a textured metal surface can support spoof surface plasmon polaritons (SSPPs). In this paper, we explore a SSPPs waveguide composed of a metal block with pyramidal grooves. Under the deep subwavelength condition, theoretical formulas for calculation of dispersion relations are derived based on the modal expansion method (MEM). Using the obtained formulas, a general analysis is given about the properties of the SSPPs in the waveguides with upright and downward pyramidal grooves. It is demonstrated that the SSPPs waveguides with upright pyramidal grooves give better field-confinement. Numerical simulations are used to check the theoretical analysis and show good agreement with the analytical results. In addition, the group velocity of the SSPPs propagating along the waveguide is explored and two structures are designed to show how to trap the SSPPs on the metal surface. The calculation methodology provided in this paper can also be used to deal with the SSPPs waveguides with irregular grooves.

  15. A New Rig for Testing Textured Surfaces in Pure Sliding Conditions

    DEFF Research Database (Denmark)

    Godi, Alessandro; Grønbæk, J.; Mohaghegh, Kamran

    2013-01-01

    for cylinder liners. To prove the efficacy of a particular textured surface, it is paramount to perform experimental tests under controlled laboratory conditions. In this paper, a new test rig simulating pure sliding conditions is presented, dubbed axial sliding test. It presents four major components: a rod......, a sleeve, a housing and a stripwound container. The rod and the sleeve are the two surfaces in relative sliding motion; the stripwound container maintains a constant, but adjustable normal pressure, and the housing serves as interface between the sleeve and the container. For carrying out the test, two......-turned rod against a mirror-polished sleeve. Qualitatively, the multifunctional surfaces improve the friction conditions, but a more structured test campaign is required. It is furthermore assessed the repeatability of the test device, in order to rely on the results obtained. Ten repetitions made...

  16. Evolution of texture and microstructure in pulsed electro-deposited Cu treated by Surface Mechanical Attrition Treatment (SMAT)

    Energy Technology Data Exchange (ETDEWEB)

    Blonde, Romain [LETAM, CNRS 3143, Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Chan, Hoi-Lam [The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Allain-Bonasso, Nathalie [LETAM, CNRS 3143, Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Bolle, Bernard [LETAM, Ecole Nationale d' Ingenieurs de Metz, Ile du Saulcy, 57045 Metz (France); Grosdidier, Thierry [LETAM, CNRS 3143, Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Lu, Jian, E-mail: mmmelu@inet.polyu.edu.h [The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

    2010-08-15

    This paper presents the microstructure and texture evolution in pulsed electro-deposited copper samples and the additional effect of the Surface Mechanical Attrition Treatment (SMAT), which were analyzed by means of electron backscattering and X-ray diffractions. A transition in the microstructure was observed as the thickness of the deposit increased: from randomly oriented equiaxed (3D) nanograins at the beginning of the deposition process towards elongated (2D) nanograins having a strong <1 1 0> fibre texture. Meanwhile, the SMAT treatment is shown to randomize the strong texture of the electrodeposits.

  17. Surface patterning of nanoparticles with polymer patches

    Science.gov (United States)

    Choueiri, Rachelle M.; Galati, Elizabeth; Thérien-Aubin, Héloïse; Klinkova, Anna; Larin, Egor M.; Querejeta-Fernández, Ana; Han, Lili; Xin, Huolin L.; Gang, Oleg; Zhulina, Ekaterina B.; Rubinstein, Michael; Kumacheva, Eugenia

    2016-10-01

    Patterning of colloidal particles with chemically or topographically distinct surface domains (patches) has attracted intense research interest. Surface-patterned particles act as colloidal analogues of atoms and molecules, serve as model systems in studies of phase transitions in liquid systems, behave as ‘colloidal surfactants’ and function as templates for the synthesis of hybrid particles. The generation of micrometre- and submicrometre-sized patchy colloids is now efficient, but surface patterning of inorganic colloidal nanoparticles with dimensions of the order of tens of nanometres is uncommon. Such nanoparticles exhibit size- and shape-dependent optical, electronic and magnetic properties, and their assemblies show new collective properties. At present, nanoparticle patterning is limited to the generation of two-patch nanoparticles, and nanoparticles with surface ripples or a ‘raspberry’ surface morphology. Here we demonstrate nanoparticle surface patterning, which utilizes thermodynamically driven segregation of polymer ligands from a uniform polymer brush into surface-pinned micelles following a change in solvent quality. Patch formation is reversible but can be permanently preserved using a photocrosslinking step. The methodology offers the ability to control the dimensions of patches, their spatial distribution and the number of patches per nanoparticle, in agreement with a theoretical model. The versatility of the strategy is demonstrated by patterning nanoparticles with different dimensions, shapes and compositions, tethered with various types of polymers and subjected to different external stimuli. These patchy nanocolloids have potential applications in fundamental research, the self-assembly of nanomaterials, diagnostics, sensing and colloidal stabilization.

  18. High-efficiency si/polymer hybrid solar cells based on synergistic surface texturing of Si nanowires on pyramids.

    Science.gov (United States)

    He, Lining; Lai, Donny; Wang, Hao; Jiang, Changyun; Rusli

    2012-06-11

    An efficient Si/PEDOT:PSS hybrid solar cell using synergistic surface texturing of Si nanowires (SiNWs) on pyramids is demonstrated. A power conversion efficiency (PCE) of 9.9% is achieved from the cells using the SiNW/pyramid binary structure, which is much higher than similar cells based on planar Si, pyramid-textured Si, and SiNWs. The PCE is the highest reported to-date for hybrid cells based on Si nanostructures and PEDOT.

  19. High friction on ice provided by elastomeric fiber composites with textured surfaces

    Science.gov (United States)

    Rizvi, R.; Naguib, H.; Fernie, G.; Dutta, T.

    2015-03-01

    Two main applications requiring high friction on ice are automobile tires and footwear. The main motivation behind the use of soft rubbers in these applications is the relatively high friction force generated between a smooth rubber contacting smooth ice. Unfortunately, the friction force between rubber and ice is very low at temperatures near the melting point of ice and as a result we still experience automobile accidents and pedestrian slips and falls in the winter. Here, we report on a class of compliant fiber-composite materials with textured surfaces that provide outstanding coefficients of friction on wet ice. The fibrous composites consist of a hard glass-fiber phase reinforcing a compliant thermoplastic polyurethane matrix. The glass-fiber phase is textured such that it is aligned transversally and protruding out of the elastomer surface. Our analysis indicates that the exposed fiber phase exhibits a "micro-cleat" effect, allowing for it to fracture the ice and increase the interfacial contact area thereby requiring a high force to shear the interface.

  20. Investigation of the biofouling properties of several algae on different textured chemical modified silicone surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jihai [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Wenjie, E-mail: zhaowj@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Peng, Shusen; Zeng, Zhixiang; Zhang, Xin [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wu, Xuedong, E-mail: xdwu@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Xue, Qunji [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2014-08-30

    Highlights: • Engineered pillars, pits and grooves spaced 3–12 μm apart were fabricated on siloxane modified acrylic resin films. • The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. • The feature size and geometry displayed a substantial correlation with the antifouling properties. • A comparatively physical fouling deterrent mechanism was analyzed. - Abstract: Engineered pillars, pits and grooves spaced 3, 6, 9 and 12 μm apart were fabricated on siloxane modified acrylic resin films. The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. These films showed various antifouling performances to Ulothrix, Closterium and Navicula. For Navicula (length: 10–12 μm), the feature size and geometry displayed a substantial correlation with the antifouling properties. The film with pillars spaced 3 μm reduced Navicula settlement by 73% compared to the control surface. For Closterium (length: 45–55 μm), their responses were governed by the same underlying thermodynamic principles as wettability, the largest reduction in Closterium, 81%, was obtained on the surface with grooves spaced 12 μm apart. For Ulothrix (length: 5–8 mm), the surface also showed the best antifouling performance, the reduction ratio of the settlement on the surface with grooves spaced 12 μm apart could even reach 92%. At last, physical fouling deterrent mechanisms for the films with various textures were analyzed in detail. The feature size and geometry display a substantial correlation with the antifouling properties when the size of fouling algae is close to the textures. With the increasing size for algae, antifouling performance was getting better on surface with pillars or grooves because the algae are bridged between two or more features other than stabilizing its entire mass on one single feature or able to settle between features.

  1. Laser texturing of Hastelloy C276 alloy surface for improved hydrophobicity and friction coefficient

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.

    2016-03-01

    Laser treatment of Hastelloy C276 alloy is carried out under the high pressure nitrogen assisting gas environment. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools including, scanning electron and atomic force microscopes, X-ray diffraction, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. Microhardness is measured and the residual stress formed in the laser treated surface is determined from the X-ray data. The hydrophibicity of the laser treated surface is assessed using the sessile drop method. Friction coefficient of the laser treated layer is obtained incorporating the micro-tribometer. It is found that closely spaced laser canning tracks create a self-annealing effect in the laser treated layer and lowers the thermal stress levels through modifying the cooling rates at the surface. A dense structure, consisting of fine size grains, enhances the microhardness of the surface. The residual stress formed at the surface is compressive and it is in the order of -800 MPa. Laser treatment improves the surface hydrophobicity significantly because of the formation of surface texture composing of micro/nano-pillars.

  2. Solder wetting behavior enhancement via laser-textured surface microcosmic topography

    Science.gov (United States)

    Chen, Haiyan; Peng, Jianke; Fu, Li; Wang, Xincheng; Xie, Yan

    2016-04-01

    In order to reduce or even replace the use of Sn-Pb solder in electronics industry, the laser-textured surface microstructures were used to enhance the wetting behavior of lead free solder during soldering. According to wetting theory and Sn-Ag-Cu lead free solder performance, we calculated and designed four microcosmic structures with the similar shape and different sizes to control the wetting behavior of lead free solder. The micro-structured surfaces with different dimensions were processed on copper plates by fiber femtosecond laser, and the effect of microstructures on wetting behavior was verified experimentally. The results showed that the wetting angle of Sn-Ag-Cu solder on the copper plate with microstructures decreased effectively compared with that on the smooth copper plate. The wetting angles had a sound fit with the theoretical values calculated by wetting model. The novel method provided a feasible route for adjusting the wetting behavior of solders and optimizing solders system.

  3. Influence of surface texture on the galling characteristics of lean duplex and austenitic stainless steels

    DEFF Research Database (Denmark)

    Wadman, Boel; Eriksen, J.; Olsson, M.;

    2010-01-01

    of sheet materials and lubricants. The strip reduction test, a severe sheet forming tribology test was used to simulate the conditions during ironing. This investigation shows that the risk of galling is highly dependent on the surface texture of the duplex steel. Trials were also performed......Two simulative test methods were used to study galling in sheet forming of two types of stainless steel sheet: austenitic (EN 1.4301) and lean duplex LDX 2101 (EN 1.4162) in different surface conditions. The pin-on-disc test was used to analyse the galling resistance of different combinations...... in an industrial tool used for high volume production of pump components, to compare forming of LDX 2101 and austenitic stainless steel with equal thickness. The forming forces, the geometry and the strains in the sheet material were compared for the same component. It was found that LDX steels can be formed...

  4. Regenerated collagen fibers with grooved surface texture: Physicochemical characterization and cytocompatibility.

    Science.gov (United States)

    Wang, Xiang; Wu, Tong; Wang, Wei; Huang, Chen; Jin, Xiangyu

    2016-01-01

    A novel type of protein fibers, regenerated collagen fibers (RC) from cattle skin, was prepared through wet-spinning. Due to the combined effect of solvent exchange and subsequent drawing process, the fibers were found to have a grooved surface texture. The grooves provided not only ordered topographical cues, but also increased surface area. Protein content of the RC fibers was confirmed by Fourier Transform infrared spectroscopy (FTIR) and ninhydrin color reaction. The fibers could be readily fabricated into nonwovens or other textiles, owning to their comparable physical properties to other commercialized fibers. Cell growth behavior on RC nonwovens suggested both early adhesion and prompt proliferation. The high moisture regain, good processability, along with the excellent cytocompatibility indicated that the RC fibers and nonwovens developed in this study might offer a good candidate for biomedical and healthcare applications.

  5. A synergetic effect of surface texture and field-effect passivations on improving Si solar cell performance

    Science.gov (United States)

    Qiu, Ying; Wang, Liangxing; Hao, Hongchen; Shi, Wei; Lu, Ming

    2015-07-01

    P-type Si substrate based solar cells were prepared with indium-tin-oxide thin films as the front top electrodes and Al layers as the rear ones. A synergetic effect of surface texture and field-effect passivations on improving Si solar cell performance was investigated. The surface texture was conducted by NaOH etching of Si, and field-effect passivations were performed by introducing SiO2 and Al2O3 thin film layers at the front and rear sides of the Si solar cell, respectively. The surface texture treatment makes the Si solar cell efficiency increase from 9.81% to 11.08%. After the synergetic treatments of surface texture and field-effect passivations, the efficiency further increased to 15.04%, that is, a more than 50% relative efficiency enhancement was obtained. This work demonstrates the significant effectiveness and facile applicability of the synergetic effect of surface texture and field-effect passivations on improving Si solar cell performance.

  6. Some unusual electronic patterns on graphite surface

    Indian Academy of Sciences (India)

    Shyam K Choudhury; Anjan K Gupta

    2008-02-01

    We report on the observation of some unusual electronic patterns on a graphite surface using scanning tunneling spectroscopy (STM). We attribute these patterns to different types of strain near the surface. One such pattern seen on a particular layer comprises of two-dimensional spatially varying super-lattice and one-dimensional fringes. This pattern is present in a finite region of a layer on the surface confined between two carbon fibers. We attribute this spatially varying super-lattice structure to the shear strain generated in the top layer due to the restraining fibers. We have also developed a model with the Moirµe rotation hypothesis that gives us a better insight into such large-scale spatially varying patterns. We have been able to model the above-observed pattern. We also report another pattern near a defect, which we attribute to the change in density of states due to the physical buckling of the top graphite layer. Part of this buckled layer is found to be buried under another layer and this region shows a reversed contrast and thus supporting our idea of buckling. We also performed tunneling spectroscopy measurements on various regions of these patterns which show significant variations in the density of states.

  7. Interfacial molecular assem- bly and surface patterning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on a brief review of the traditional surface patterning research, this article introduces the recent progress in the research on surface patterning via molecular self-assembly. Because the size scale of molecular self-as- semblies is in the range of 1-100 nm, the method of molecular self-assembly can easily lead to the construction of ordered structures in nanometer scale, and thus break through the size limit of traditional lithography. Some novel ways of molecular self-assembly for surface patterning are particularly introduced in this review, including supramo- lecular architecture at interface, chemisorption of dendron thoils, and surface aggregation of bolaform amphiphiles. Provided that we know more and more about the basic principles governing the surface morphology, it is believed that interfacial molecular assembly would be a very competitive supramolecular technique, and a potential application in many fields such as surface property adjustment, organic patterned devices, surface molecular recognition, and com-binatorial chemistry is greatly anticipated.

  8. Conducting elastomer surface texturing: a path to electrode spotting. Application to the biochip production.

    Science.gov (United States)

    Marquette, Christophe A; Blum, Loïc J

    2004-09-15

    A new active support for electro-chemiluminescent biochip preparation has been developed. This material was based on an original material composed of graphite modified polydimethyl siloxane (PDMS). The addressed inclusion of Sepharose beads at the surface of this elastomeric electrode generated interesting local high specific surface. The electrode was characterised by electrochemical (cyclic voltametry, chronoamperomatry) and imaging (scanning electron microscopy (SEM)) methods, and a surface area increase factor of 50 was found, linked to the texturing of the surface generated by the presence of the Sepharose beads. The consequence of this increase was shown to be a jump of the local electrochemical activity which induced a well defined and localised electro-chemiluminescent signal. The new material was used to design biochips based on the electro-chemiluminescent reaction of luminol with enzymatically produced hydrogen peroxide. Thus, when using beads bearing bio-molecules such nucleic acid or human IgG, in conjunction with glucose oxidas-labelled DNA or antibody, sensitive biochips could be obtained with detection limits of 10(11) and 10(10) molecules, respectively. Multi-parameter enzyme-based biochips could also be achieved by locally adsorbing, at the PDMS-graphite surface, either glucose oxidase, lactate oxidase or choline oxidase. Detection limits of 10 microM for lactate and choline and 20 microM for glucose were found, with detection ranging over two decades at least.

  9. Texture Analysis of Hydrophobic Polycarbonate and Polydimethylsiloxane Surfaces via Persistent Homology

    Directory of Open Access Journals (Sweden)

    Ali Nabi Duman

    2017-09-01

    Full Text Available Due to recent climate change-triggered, regular dust storms in the Middle East, dust mitigation has become the critical issue for solar energy harvesting devices. One of the methods to minimize and prevent dust adhesion and create self-cleaning abilities is to generate hydrophobic characteristics on surfaces. The purpose of this study is to explore the topological features of hydrophobic surfaces. We use non-standard techniques from topological data analysis to extract morphological features from the AFM images. Our method recovers most of the previous qualitative observations in a robust and quantitative way. Persistence diagrams, which is a summary of topological structures, witness quantitatively that the crystallized polycarbonate (PC surface possesses spherulites, voids, and fibrils, and the texture height and spherulite concentration increases with the increased immersion period. The approach also shows that the polydimethylsiloxane (PDMS exactly copied the structures at the PC surface but 80 to 90 percent of the nanofibrils were not copied at PDMS surface. We next extract a feature vector from each persistence diagram to show which experiments hold features with similar variance using principal component analysis (PCA. The K-means clustering algorithm is applied to the matrix of feature vectors to support the PCA result, grouping experiments with similar features.

  10. Modification of wetting property of Inconel 718 surface by nanosecond laser texturing

    Science.gov (United States)

    Yang, Z.; Tian, Y. L.; Yang, C. J.; Wang, F. J.; Liu, X. P.

    2017-08-01

    Topographic and wetting properties of Inconel 718 (IN718) surfaces were modified via nanosecond laser treatment. In order to investigate surface wetting behavior without additional post treatment, three kinds of microstructures were created on IN718 surfaces, including line pattern, grid pattern and spot pattern. From the viewpoint of surface morphology, the results show that laser ablated grooves and debris significantly altered the surface topography as well as surface roughness compared with the non-treated surfaces. The effects of laser parameters, such as laser scanning speed and laser power, on surface features were also discussed. We have observed the laser treated surfaces of IN718 showed very high hydrophilicity just after laser ablation under ambient air condition. And this hydrophilic property has changed rapidly to the other state, very high hydrophobicity over about 20 days. Further experiments and analysis have been carried out so as to investigate this phenomenon. Based on the XPS analysis, the results indicate that the change of wetting property from hydrophilic to hydrophobic over time may be due to the surface chemistry modifications, especially carbon content. After the contact angles reached steady state, the maximum water contact angle (WCA) for line-patterned and grid-patterned surfaces increased to 152.3 ± 1.2° and 156.8 ± 1.1° with the corresponding rolling angle (RA) of 8.8 ± 1.1° and 6.5 ± 0.8°, respectively. These treated IN718 surfaces exhibited superhydrophobic property. However, the maximum WCA for the spot-patterned surfaces just increased to 140.8 ± 2.8° with RA above 10°. Therefore, it is deduced that laser-inscribed modification of surface wettability has high sensitivity to surface morphology and surface chemical compositions. This work can be utilized to optimize the laser processing parameters so as to fabricate desired IN718 surfaces with hydrophobic or even superhydrophobic property and thus extend the applications

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

    Science.gov (United States)

    Gu, Xin; Yu, Xuegong; Liu, Tao; Li, Dongsheng; Yang, Deren

    2011-01-01

    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.

  12. Coupling between elytra of some beetles: Mechanism, forces and effect of surface texture

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Lightweight materials, structures and coupling mechanisms are very important for realizing advanced flight vehicles. Here, we obtained the geometric structures and morphologies of the elytra of beetles and ascertained its coupling zone by using the histological section technique and SEM. We set up a three-dimensional motion observing system to monitor the opening and closing behaviour of elytra in beetles and to determine the motion mechanism. We constructed a force measuring system to measure the coupling forces between elytra. The results show that elytra open and close by rotating about a single axle, where the coupling forces may be as high as 160 times its own bodyweight, the elytra coupling with the tenon and mortise mechanism, surface texture and opening angle between elytra heavily influence the coupling forces. These results may provide insights into the design mechanism and structure for future vehicles of flight.

  13. Influence of Conditioned Surface Textures on Plain Journal Bearing Performance Working on HL Conditions

    Directory of Open Access Journals (Sweden)

    Vélez-Restrepo J.M.

    2012-07-01

    Full Text Available As an answer to the need for reducing friction losses on bearings, dynamic seals, piston rings, cutting tools and others, a lot of work has been dedicated to mechanical systems study whose surfaces have been textured in a controlled way. Theoretical models and experimental results have shown improvements on the tribological performance of these systems regarding untextured systems, working under the same conditions. This paper presents a numerical model for getting relationships among the operational conditions (load, speed, and dynamic viscosity, the minimum lubricate film thickness, the friction coefficient and the conditioned micro-topography of a plain sliding bearing working under a hydrodynamic regime. Moreover, regarding other similar works the constructed model allows studying the combined effect of the micro-wedges that work as micro-bearings, and the typical convergent macro-wedge of these study elements.

  14. The Soil Characteristic Curve at Low Water Contents: Relations to Specific Surface Area and Texture

    DEFF Research Database (Denmark)

    Resurreccion, Augustus; Møldrup, Per; Schjønning, Per;

    Accurate description of the soil-water retention curve (SWRC) at low water contents is important for simulating water dynamics, plant-water relations, and microbial processes in surface soil. Soil-water retention at soil-water matric potential of less than -10 MPa, where adsorptive forces dominate...... that measurements by traditional pressure plate apparatus generally overestimated water contents at -1.5 MPa (plant wilting point). The 41 soils were classified into four textural classes based on the so-called Dexter index n (= CL/OC), and the Tuller-Or (TO) general scaling model describing the water film...... thickness at a given soil-water matric potential (low organic soils with n > 10, the estimated SA from the dry soil-water retention was in good agreement with the SA measured using ethylene glycol monoethyl ether (SA_EGME). A strong relationship between the ratio...

  15. Textural, surface, thermal and sorption properties of the functionalized activated carbons and carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Nowicki Piotr

    2015-12-01

    Full Text Available Two series of functionalised carbonaceous adsorbents were prepared by means of oxidation and nitrogenation of commercially available activated carbon and multi-walled carbon nanotubes. The effect of nitrogen and oxygen incorporation on the textural, surface, thermal and sorption properties of the adsorbents prepared was tested. The materials were characterized by elemental analysis, low-temperature nitrogen sorption, thermogravimetric study and determination of the surface oxygen groups content. Sorptive properties of the materials obtained were characterized by the adsorption of methylene and alkali blue 6B as well as copper(II ions. The final products were nitrogen- and oxygen-enriched mesoporous adsorbents of medium-developed surface area, showing highly diverse N and O-heteroatom contents and acidic-basic character of the surface. The results obtained in our study have proved that through a suitable choice of the modification procedure of commercial adsorbents it is possible to produce materials with high sorption capacity towards organic dyes as well as copper(II ions.

  16. Surface Patterning and Nanowire Biosensor Construction

    DEFF Research Database (Denmark)

    Iversen, Lars

    2008-01-01

    surface. A central limitation to this biosensor principle is the screening of analyte charge by mobile ions in electrolytes with physiological ionic strength. To overcome this problem, we propose to use as capture agents proteins which undergo large conformational changes. Using structure based protein...... be biofunctionalized, integrated in FETs, and used to detect charged species, as shown for H+ ions for pH sensing....... assembly on e.g. glass surfaces, providing parallel patterning via gentle and oriented protein immobilization. Such protein patterns are useful for miniaturized bioassays of protein function. Second, in a very different approach, we use a highly focused laser beam to locally desorb alkanethiols from a self...

  17. Influence of ceramic surface texture on the wear of gold alloy and heat-pressed ceramics.

    Science.gov (United States)

    Saiki, Osamu; Koizumi, Hiroyasu; Nogawa, Hiroshi; Hiraba, Haruto; Akazawa, Nobutaka; Matsumura, Hideo

    2014-01-01

    The purpose of this study was to evaluate the influence of ceramic surface texture on the wear of rounded rod specimens. Plate specimens were fabricated from zirconia (ZrO2), feldspathic porcelain, and lithium disilicate glass ceramics (LDG ceramics). Plate surfaces were either ground or polished. Rounded rod specimens with a 2.0-mm-diameter were fabricated from type 4 gold alloy and heat-pressed ceramics (HP ceramics). Wear testing was performed by means of a wear testing apparatus under 5,000 reciprocal strokes of the rod specimen with 5.9 N vertical loading. The results were statistically analyzed with a non-parametric procedure. The gold alloy showed the maximal height loss (90.0 µm) when the rod specimen was abraded with ground porcelain, whereas the HP ceramics exhibited maximal height loss (49.8 µm) when the rod specimen was abraded with ground zirconia. There was a strong correlation between height loss of the rod and surface roughness of the underlying plates, for both the gold alloy and HP ceramics.

  18. Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture

    Directory of Open Access Journals (Sweden)

    Gabriele Bitelli

    2012-07-01

    Full Text Available The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey.

  19. Regenerated collagen fibers with grooved surface texture: Physicochemical characterization and cytocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Wu, Tong [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Wang, Wei [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Huang, Chen, E-mail: hc@dhu.edu.cn [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Jin, Xiangyu [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China)

    2016-01-01

    A novel type of protein fibers, regenerated collagen fibers (RC) from cattle skin, was prepared through wet-spinning. Due to the combined effect of solvent exchange and subsequent drawing process, the fibers were found to have a grooved surface texture. The grooves provided not only ordered topographical cues, but also increased surface area. Protein content of the RC fibers was confirmed by Fourier Transform infrared spectroscopy (FTIR) and ninhydrin color reaction. The fibers could be readily fabricated into nonwovens or other textiles, owning to their comparable physical properties to other commercialized fibers. Cell growth behavior on RC nonwovens suggested both early adhesion and prompt proliferation. The high moisture regain, good processability, along with the excellent cytocompatibility indicated that the RC fibers and nonwovens developed in this study might offer a good candidate for biomedical and healthcare applications. - Highlights: • Wet-spun regenerated collagen fibers having aligned surface grooves • Comparable physiochemical properties to commercialized fibers • Readily processed into nonwovens • Excellent cytocompatibility with prompt cell adhesion and proliferation.

  20. Femtosecond laser surface texturing of titanium as a method to reduce the adhesion of Staphylococcus aureus and biofilm formation

    Science.gov (United States)

    Cunha, Alexandre; Elie, Anne-Marie; Plawinski, Laurent; Serro, Ana Paula; Botelho do Rego, Ana Maria; Almeida, Amélia; Urdaci, Maria C.; Durrieu, Marie-Christine; Vilar, Rui

    2016-01-01

    The aim of the present work was to investigate the possibility of using femtosecond laser surface texturing as a method to reduce the colonization of Grade 2 Titanium alloy surfaces by Staphylococcus aureus and the subsequent formation of biofilm. The laser treatments were carried out with a Yb:KYW chirped-pulse-regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. Two types of surface textures, consisting of laser-induced periodic surface structures (LIPSS) and nanopillars, were produced. The topography, chemical composition and phase constitution of these surfaces were investigated by atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction. Surface wettability was assessed by the sessile drop method using water and diiodomethane as testing liquids. The response of S. aureus put into contact with the laser treated surfaces in controlled conditions was investigated by epifluorescence microscopy and scanning electron microscopy 48 h after cell seeding. The results achieved show that the laser treatment reduces significantly the bacterial adhesion to the surface as well as biofilm formation as compared to a reference polished surfaces and suggest that femtosecond laser texturing is a simple and promising method for endowing dental and orthopedic titanium implants with antibacterial properties, reducing the risk of implant-associated infections without requiring immobilized antibacterial substances, nanoparticles or coatings.

  1. Trend patterns in global sea surface temperature

    DEFF Research Database (Denmark)

    Barbosa, S.M.; Andersen, Ole Baltazar

    2009-01-01

    Isolating long-term trend in sea surface temperature (SST) from El Nino southern oscillation (ENSO) variability is fundamental for climate studies. In the present study, trend-empirical orthogonal function (EOF) analysis, a robust space-time method for extracting trend patterns, is applied...

  2. Wafer Surface Charge Reversal as a Method of Simplifying Nanosphere Lithography for Reactive Ion Etch Texturing of Solar Cells

    Directory of Open Access Journals (Sweden)

    Daniel Inns

    2007-01-01

    Full Text Available A simplified nanosphere lithography process has been developed which allows fast and low-waste maskings of Si surfaces for subsequent reactive ion etching (RIE texturing. Initially, a positive surface charge is applied to a wafer surface by dipping in a solution of aluminum nitrate. Dipping the positive-coated wafer into a solution of negatively charged silica beads (nanospheres results in the spheres becoming electrostatically attracted to the wafer surface. These nanospheres form an etch mask for RIE. After RIE texturing, the reflection of the surface is reduced as effectively as any other nanosphere lithography method, while this batch process used for masking is much faster, making it more industrially relevant.

  3. Nuclear Technology. Course 27: Metrology. Module 27-4, Angle Measurement Instruments, Optical Projections and Surface Texture Gages.

    Science.gov (United States)

    Selleck, Ben; Espy, John

    This fourth in a series of eight modules for a course titled Metrology describes the universal bevel protractor and the sine bar, the engineering microscope and optical projector, and several types of surface texture gages. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3)…

  4. Cooling Enhancement by Drop Impact and Pool Boiling on Nano-textured Surfaces Under Normal Gravity Conditions and at Zero and Increased Gravity in Parabolic Flights

    Science.gov (United States)

    Yarin, Alexander; Sinha-Ray, Suman; Jun, Seongchul

    2014-03-01

    The earth experiments with drop impact onto metal-plated electrospun nanofiber mats encompass a single drop, or drop trains or jets impacts. The results on drop cooling and pool boiling on nano-textured surface were obtained during the parabolic flights supported by NASA and ESA. Pool boiling on nano-textured surfaces was studied for ethanol and water as working fluids. The nano-textured surfaces were copper platelets covered with copper-plated electrospun nanofibers. The results revealed that the heat flux in boiling on the nano-textured surfaces was about 3-8 times higher than that on the bare copper. This stems from the fact that nano-textured surfaces promote bubble growth by increasing the average temperature of fluid surrounding growing bubbles. Nano-textured surfaces facilitated bubble growth rate and increase bubble detachment frequency. On the other hand, the critical heat flux (CHF) on the nano-textured surfaces was found to be very close to its counterpart on the bare copper surfaces. However, the heat flux on the nano-textured surfaces in transition boiling was significantly higher than on the bare copper ones, since the presence of nanofibers prevented bubble merging and delayed formation of vapor film.

  5. Wetting transition on patterned surfaces: transition states and energy barriers.

    Science.gov (United States)

    Ren, Weiqing

    2014-03-18

    We study the wetting transition on microstructured hydrophobic surfaces. We use the string method [J. Chem. Phys. 2007, 126, 164103; J. Chem. Phys. 2013, 138, 134105] to accurately compute the transition states, the energy barriers, and the minimum energy paths for the wetting transition from the Cassie-Baxter state to the Wenzel state. Numerical results are obtained for the wetting of a hydrophobic surface textured with a square lattice of pillars. It is found that the wetting of the solid substrate occurs via infiltration of the liquid in a single groove, followed by lateral propagation of the liquid front. The propagation of the liquid front proceeds in a stepwise manner, and a zipping mechanism is observed during the infiltration of each layer. The minimum energy path for the wetting transition goes through a sequence of intermediate metastable states, whose wetted areas reflect the microstructure of the patterned surface. We also study the dependence of the energy barrier on the drop size and the gap between the pillars.

  6. Surface Evolution of Nano-Textured 4H–SiC Homoepitaxial Layers after High Temperature Treatments: Morphology Characterization and Graphene Growth

    Directory of Open Access Journals (Sweden)

    Xingfang Liu

    2015-09-01

    Full Text Available Nano-textured 4H–SiC homoepitaxial layers (NSiCLs were grown on 4H–SiC(0001 substrates using a low pressure chemical vapor deposition technique (LPCVD, and subsequently were subjected to high temperature treatments (HTTs for investigation of their surface morphology evolution and graphene growth. It was found that continuously distributed nano-scale patterns formed on NSiCLs which were about submicrons in-plane and about 100 nanometers out-of-plane in size. After HTTs under vacuum, pattern sizes reduced, and the sizes of the remains were inversely proportional to the treatment time. Referring to Raman spectra, the establishment of multi-layer graphene (MLG on NSiCL surfaces was observed. MLG with sp2 disorders was obtained from NSiCLs after a high temperature treatment under vacuum at 1700 K for two hours, while MLG without sp2 disorders was obtained under Ar atmosphere at 1900 K.

  7. Fabrication of friction-reducing texture surface by selective laser melting of ink-printed (SLM-IP) copper (Cu) nanoparticles(NPs)

    Science.gov (United States)

    Wang, Xinjian; Liu, Junyan; Wang, Yang; Fu, Yanan

    2017-02-01

    This paper reports a process of selective laser melting of ink-printed (SLM-IP) copper (Cu) nanoparticles(NPs) for the fabrication of full dense Cu friction-reducing texture on the metallic surface in ambient condition. This technique synthesizes pure Cu by chemical reduction route using an organic solvent during laser melting in the atmosphere environment, and provides a flexible additive manufacture approach to form complex friction-reduction texture on the metallic surface. Microtextures of ring and disc arrays have been fabricated on the stainless steel surface by SLM-IP Cu NPs. The friction coefficient has been measured under the lubricating condition of the oil. Disc texture surface (DTS) has a relatively low friction coefficient compared with ring texture surface (RTS), Cu film surface (Cu-FS) and the untreated substrate. The study suggests a further research on SLM-IP approach for complex microstructure or texture manufacturing, possibly realizing its advantage of flexibility.

  8. Light-Induced Surface Patterning of Silica.

    Science.gov (United States)

    Kang, Hong Suk; Lee, Seungwoo; Choi, Jaeho; Lee, Hongkyung; Park, Jung-Ki; Kim, Hee-Tak

    2015-10-27

    Manipulating the size and shape of silica precursor patterns using simple far-field light irradiation and transforming such reconfigured structures into inorganic silica patterns by pyrolytic conversion are demonstrated. The key concept of our work is the use of an azobenzene incorporated silica precursor (herein, we refer to this material as azo-silane composite) as ink in a micromolding process. The moving direction of azo-silane composite is parallel to light polarization direction; in addition, the amount of azo-silane composite movement can be precisely determined by controlling light irradiation time. By exploiting this peculiar phenomenon, azo-silane composite patterns produced using the micromolding technique are arbitrarily manipulated to obtain various structural features including high-resolution size or sophisticated shape. The photoreconfigured patterns formed with azo-silane composites are then converted into pure silica patterns through pyrolytic conversion. The pyrolytic converted silica patterns are uniformly formed over a large area, ensuring crack-free formation and providing high structural fidelity. Therefore, this optical manipulation technique, in conjunction with the pyrolytic conversion process, opens a promising route to the design of silica patterns with finely tuned structural features in terms of size and shape. This platform for designing silica structures has significant value in various nanotechnology fields including micro/nanofluidic channel for lab-on-a-chip devices, transparent superhydrophobic surfaces, and optoelectronic devices.

  9. Classification of grass pollen through the quantitative analysis of surface ornamentation and texture.

    Science.gov (United States)

    Mander, Luke; Li, Mao; Mio, Washington; Fowlkes, Charless C; Punyasena, Surangi W

    2013-11-07

    Taxonomic identification of pollen and spores uses inherently qualitative descriptions of morphology. Consequently, identifications are restricted to categories that can be reliably classified by multiple analysts, resulting in the coarse taxonomic resolution of the pollen and spore record. Grass pollen represents an archetypal example; it is not routinely identified below family level. To address this issue, we developed quantitative morphometric methods to characterize surface ornamentation and classify grass pollen grains. This produces a means of quantifying morphological features that are traditionally described qualitatively. We used scanning electron microscopy to image 240 specimens of pollen from 12 species within the grass family (Poaceae). We classified these species by developing algorithmic features that quantify the size and density of sculptural elements on the pollen surface, and measure the complexity of the ornamentation they form. These features yielded a classification accuracy of 77.5%. In comparison, a texture descriptor based on modelling the statistical distribution of brightness values in image patches yielded a classification accuracy of 85.8%, and seven human subjects achieved accuracies between 68.33 and 81.67%. The algorithmic features we developed directly relate to biologically meaningful features of grass pollen morphology, and could facilitate direct interpretation of unsupervised classification results from fossil material.

  10. Surface texture and hardness of dental alloys processed by alternative technologies

    Science.gov (United States)

    Porojan, Liliana; Savencu, Cristina E.; Topală, Florin I.; Porojan, Sorin D.

    2017-08-01

    Technological developments have led to the implementation of novel digitalized manufacturing methods for the production of metallic structures in prosthetic dentistry. These technologies can be classified as based on subtractive manufacturing, assisted by computer-aided design/computer-aided manufacturing (CAD/CAM) systems, or on additive manufacturing (AM), such as the recently developed laser-based methods. The aim of the study was to assess the surface texture and hardness of metallic structures for dental restorations obtained by alternative technologies: conventional casting (CST), computerized milling (MIL), AM power bed fusion methods, respective selective laser melting (SLM) and selective laser sintering (SLS). For the experimental analyses metallic specimens made of Co-Cr dental alloys were prepared as indicated by the manufacturers. The specimen structure at the macro level was observed by an optical microscope and micro-hardness was measured in all substrates. Metallic frameworks obtained by AM are characterized by increased hardness, depending also on the surface processing. The formation of microstructural defects can be better controlled and avoided during SLM and MIL process. Application of power bed fusion techniques, like SLS and SLM, is currently a challenge in dental alloys processing.

  11. Scatterometry—fast and robust measurements of nano-textured surfaces

    Science.gov (United States)

    Hannibal Madsen, Morten; Hansen, Poul-Erik

    2016-06-01

    Scatterometry is a fast, precise and low cost way to determine the mean pitch and dimensional parameters of periodic structures with lateral resolution of a few nanometer. It is robust enough for in-line process control and precise and accurate enough for metrology measurements. Furthermore, scatterometry is a non-destructive technique capable of measuring buried structures, for example a grating covered by a thick oxide layer. As scatterometry is a non-imaging technique, mathematical modeling is needed to retrieve structural parameters that describe a surface. In this review, the three main steps of scatterometry are discussed: the data acquisition, the simulation of diffraction efficiencies and the comparison of data and simulations. First, the intensity of the diffracted light is measured with a scatterometer as a function of incoming angle, diffraction angle and/or wavelength. We discuss the evolution of the scatterometers from the earliest angular scatterometers to the new imaging scatterometers. The basic principle of measuring diffraction efficiencies in scatterometry has remained the same since the beginning, but the instrumental improvements have made scatterometry a state-of-the-art solution for fast and accurate measurements of nano-textured surfaces. The improvements include extending the wavelength range from the visible to the extreme ultra-violet range, development of Fourier optics to measure all diffraction orders simultaneously, and an imaging scatterometer to measure area of interests smaller than the spot size. Secondly, computer simulations of the diffraction efficiencies are discussed with emphasis on the rigorous coupled-wave analysis (RCWA) method. RCWA has, since the mid-1990s, been the preferred method for grating simulations due to the speed of the algorithms. In the beginning the RCWA method suffered from a very slow convergence rate, and we discuss the historical improvements to overcome this challenge, e.g. by the introduction of Li

  12. Surface texture change on-demand and microfluidic devices based on thickness mode actuation of dielectric elastomer actuators (DEAs)

    Science.gov (United States)

    Ankit, Ankit; Nguyen, Anh Chien; Mathews, Nripan

    2017-04-01

    Tactile feedback devices and microfluidic devices have huge significance in strengthening the area of robotics, human machine interaction and low cost healthcare. Dielectric Elastomer Actuators (DEAs) are an attractive alternative for both the areas; offering the advantage of low cost and simplistic fabrication in addition to the high actuation strains. The inplane deformations produced by the DEAs can be used to produce out-of-plane deformations by what is known as the thickness mode actuation of DEAs. The thickness mode actuation is achieved by adhering a soft passive layer to the DEA. This enables a wide area of applications in tactile applications without the need of complex systems and multiple actuators. But the thickness mode actuation has not been explored enough to understand how the deformations can be improved without altering the material properties; which is often accompanied with increased cost and a trade off with other closely associated material properties. We have shown the effect of dimensions of active region and non-active region in manipulating the out-of-plane deformation. Making use of this, we have been able to demonstrate large area devices and complex patterns on the passive top layer for the surface texture change on-demand applications. We have also been able to demonstrate on-demand microfluidic channels and micro-chambers without the need of actually fabricating the channels; which is a cost incurring and cumbersome process.

  13. Effects of texture on salt precipitation dynamics and deposition patterns in drying porous media

    Science.gov (United States)

    Norouzi Rad, Mansoureh; Shokri, Nima

    2015-04-01

    Understanding the physics of water evaporation from saline porous media is important in many natural and engineering applications such as durability of building materials and preservation of monuments, CO2 sequestration and water quality. Also excess of salt accumulation in soil may result in soil salinization which is a global problem adversely affecting vegetation, plant growth and crop production. Thus it is important to understand the parameters affecting salt transport and precipitation in porous media. We applied X-ray micro-tomography to investigate the dynamics of salt precipitation during evaporation from porous media as influenced by the particle and pore sizes. The packed beds were saturated with NaCl solution of 3 Molal and the time-lapse X-ray imaging was continued for one day. The results show that the presence of preferential evaporation sites (associated with fine pores) on the surface of the sand columns influences significantly the patterns and dynamics of NaCl precipitation (Norouzi Rad et al., 2013; Norouzi Rad and Shokri, 2014). They confirm the formation of an increasingly thick and discrete salt crust with increasing grain size in the sand column due to the presence of fewer fine pores (preferential precipitation sites) at the surface compared to the sand packs with finer grains. Fewer fine pores on the surface also results in shorter stage-1 precipitation for the columns with larger grain sizes. A simple model for the evolution of salt crust thickness based on this principle shows a good agreement with our experiments. Our results provide new insights regarding the physics of salt precipitation and its complex dynamics in porous media during evaporation. References Norouzi Rad, M., Shokri, N., Sahimi, M. (2013), Pore-Scale Dynamics of Salt Precipitation in Drying Porous Media, Phys. Rev. E, 88, 032404. Norouzi Rad, M., Shokri, N. (2014), Effects of grain angularity on NaCl precipitation in porous media during evaporation, Water Resour. Res

  14. Computer Modeling of the Surface Texture Treated by Mill with Curved Cutting Edge

    Directory of Open Access Journals (Sweden)

    M. S. Potapova

    2015-01-01

    Full Text Available Application of mills with a curvilinear profile of the cutting edge (often called rough end mills allows us to increase milling rate, but a roughness of the surface treated by such mills is higher, than after milling by the "ordinary" mills with the "smooth" cutting edge. Deterioration of a roughness is caused by a curvature of cutting edge. The shape and sizes of a profile are of crucial importance for forming roughness on a surface. A literary review revealed that depending on a profile of the cutting edge the roughness of the machined surface makes Ra2…12,5μm.There is a developed parametrical computer model to visualize roughness formed on a surface after milling by the fluting cutter and curved cutting edge mill. The computer model also allows a 3D chip type to be cut off from a work-piece by the mills with various cutting edge profiles. When developing the model it was assumed that the tilt angle of a cutting flute is equal 0 °, a trajectory of the tooth movement is a circle rather than a trochoidal curve.An experimental test of the model has shown that the radial beats of the mill teeth have a very significant effect on the extent of the roughness formed on the machined surface. After amendments - taking into consideration teeth beats - introduced into model the modeling error made less than 5% that can be explained by the fact that profile parameters of the cutting edge of mills embedded in the model are inaccurate because of the tilt angle the cutting flutes.The analysis of the surface model has shown that after milling the work piece has a cellular structure. Each tooth with curved cutting edge forms the cell repeating with the next turn of a mill. The adjacent teeth form identical cells displaced in the feed path with respect to the cell formed by the previous tooth by the chip load Sz. Unlike processing by the ordinary mills with the "smooth" cutting edge in this case on a surface there is a surface texture not only in the feed

  15. Hybrid micro/nano-structure formation by angular laser texturing of Si surface for surface enhanced Raman scattering.

    Science.gov (United States)

    Xu, Kaichen; Zhang, Chentao; Zhou, Rui; Ji, Rong; Hong, Minghui

    2016-05-16

    Surface enhanced Raman spectroscopy (SERS) has drawn much research interest in the past decades as an efficient technique to detect low-concentration molecules. Among many technologies, which can be used to fabricate SERS substrates, laser ablation is a simple and high-speed method to produce large-area SERS substrates. This work investigates the angular texturing effect by dynamic laser ablation and its influence on SERS signals. By tuning the angle between the Si surface and laser irradiation, the distributions and sizes of laser induced hybrid micro/nano-structures are studied. By decorating with a silver film, plenty of hot spots can be created among these structures for SERS. It is found that when the incident laser angle is 15° at the laser fluence of 16.0 J/cm2, the SERS performance is well optimized. This work realizes antisymmetric distribution of nanoparticles deposited on Si surface, which provides a flexible tuning of the hybrid micro/nano-structures' fabrication with high controllability for practical applications.

  16. Experimental study of light output power for vertical GaN-based light-emitting diodes with various textured surface and thickness of GaN layer

    Directory of Open Access Journals (Sweden)

    Ho-Sang Kwack

    2012-06-01

    Full Text Available The light output power (LOP of vertical-type GaN-based light emitting diodes (LED with surface roughness (texture can be changed by texture size, density, and thickness of GaN film or by the combined effects of texture formation and thickness of GaN film. We have investigated these changes experimentally and note that the enhancement of the LOP by a factor of 2.4 can be improved with optimum texturing parameters as compared to that without texturing. In addition, the LOP of GaN-based LEDs under the same texture density increase slightly as thickness of GaN film decreases. Base on these results, we have evidently demonstrated that the enhancement factors of LOP are related to the correlation between texture size (density and thickness of GaN film.

  17. A semi-automatic multiple view texture mapping for the surface model extracted by laser scanning

    Science.gov (United States)

    Zhang, Zhichao; Huang, Xianfeng; Zhang, Fan; Chang, Yongmin; Li, Deren

    2008-12-01

    Laser scanning is an effective way to acquire geometry data of the cultural heritage with complex architecture. After generating the 3D model of the object, it's difficult to do the exactly texture mapping for the real object. we take effort to create seamless texture maps for a virtual heritage of arbitrary topology. Texture detail is acquired directly from the real object in a light condition as uniform as we can make. After preprocessing, images are then registered on the 3D mesh by a semi-automatic way. Then we divide the mesh into mesh patches overlapped with each other according to the valid texture area of each image. An optimal correspondence between mesh patches and sections of the acquired images is built. Then, a smoothing approach is proposed to erase the seam between different images that map on adjacent mesh patches, based on texture blending. The obtained result with a Buddha of Dunhuang Mogao Grottoes is presented and discussed.

  18. Effect of surface texturing on superoleophobicity, contact angle hysteresis, and "robustness".

    Science.gov (United States)

    Zhao, Hong; Park, Kyoo-Chul; Law, Kock-Yee

    2012-10-23

    Previously, we reported the creation of a fluorosilane (FOTS) modified pillar array silicon surface comprising ~3-μm-diameter pillars (6 μm pitch with ~7 μm height) that is both superhydrophobic and superoleophobic, with water and hexadecane contact angles exceeding 150° and sliding angles at ~10° owing to the surface fluorination and the re-entrant structure in the side wall of the pillar. In this work, the effects of surface texturing (pillar size, spacing, and height) on wettability, contact angle hysteresis, and "robustness" are investigated. We study the static, advancing, and receding contact angles, as well as the sliding angles as a function of the solid area fraction. The results reveal that pillar size and pillar spacing have very little effect on the static and advancing contact angles, as they are found to be insensitive to the solid area fraction from 0.04 to ~0.4 as the pillar diameter varies from 1 to 5 μm and the center-to-center spacing varies from 4.5 to 12 μm. On the other hand, sliding angle, receding contact angle, and contact angle hysteresis are found to be dependent on the solid area fraction. Specifically, receding contact angle decreases and sliding angle and hysteresis increase as the solid area fraction increases. This effect can be attributable to the increase in pinning as the solid area fraction increases. Surface Evolver modeling shows that water wets and pins the pillar surface whereas hexadecane wets the pillar surface and then penetrates into the side wall of the pillar with the contact line pinning underneath the re-entrant structure. Due to the penetration of the hexadecane drop into the pillar structure, the effect on the receding contact angle and hysteresis is larger relative to that of water. This interpretation is supported by studying a series of FOTS pillar array surfaces with varying overhang thickness. With the water drop, the contact line is pinned on the pillar surface and very little overhang thickness effect

  19. A modified Cassie-Baxter relationship to explain contact angle hysteresis and anisotropy on non-wetting textured surfaces.

    Science.gov (United States)

    Choi, Wonjae; Tuteja, Anish; Mabry, Joseph M; Cohen, Robert E; McKinley, Gareth H

    2009-11-01

    The Cassie-Baxter model is widely used to predict the apparent contact angles obtained on composite (solid-liquid-air) superhydrophobic interfaces. However, the validity of this model has been repeatedly challenged by various research groups because of its inherent inability to predict contact angle hysteresis. In our recent work, we have developed robust omniphobic surfaces which repel a wide range of liquids. An interesting corollary of constructing such surfaces is that it becomes possible to directly image the solid-liquid-air triple-phase contact line on a composite interface, using an electron microscope with non-volatile organic liquids or curable polymers. Here, we fabricate a range of model superoleophobic surfaces with controlled surface topography in order to correlate the details of the local texture with the experimentally observed apparent contact angles. Based on these experiments, in conjunction with numerical simulations, we modify the classical Cassie-Baxter relation to include a local differential texture parameter which enables us to quantitatively predict the apparent advancing and receding contact angles, as well as contact angle hysteresis. This quantitative prediction also allows us to provide an a priori estimation of roll-off angles for a given textured substrate. Using this understanding we design model substrates that display extremely small or extremely large roll-off angles, as well as surfaces that demonstrate direction-dependent wettability, through a systematic control of surface topography and connectivity.

  20. Growth of wrinkle-free graphene on texture-controlled platinum films and thermal-assisted transfer of large-scale patterned graphene.

    Science.gov (United States)

    Choi, Jae-Kyung; Kwak, Jinsung; Park, Soon-Dong; Yun, Hyung Duk; Kim, Se-Yang; Jung, Minbok; Kim, Sung Youb; Park, Kibog; Kang, Seoktae; Kim, Sung-Dae; Park, Dong-Yeon; Lee, Dong-Su; Hong, Suk-Kyoung; Shin, Hyung-Joon; Kwon, Soon-Yong

    2015-01-27

    Growth of large-scale patterned, wrinkle-free graphene and the gentle transfer technique without further damage are most important requirements for the practical use of graphene. Here we report the growth of wrinkle-free, strictly uniform monolayer graphene films by chemical vapor deposition on a platinum (Pt) substrate with texture-controlled giant grains and the thermal-assisted transfer of large-scale patterned graphene onto arbitrary substrates. The designed Pt surfaces with limited numbers of grain boundaries and improved surface perfectness as well as small thermal expansion coefficient difference to graphene provide a venue for uniform growth of monolayer graphene with wrinkle-free characteristic. The thermal-assisted transfer technique allows the complete transfer of large-scale patterned graphene films onto arbitrary substrates without any ripples, tears, or folds. The transferred graphene shows high crystalline quality with an average carrier mobility of ∼ 5500 cm(2) V(-1) s(-1) at room temperature. Furthermore, this transfer technique shows a high tolerance to variations in types and morphologies of underlying substrates.

  1. Fluoride influences nickel-titanium orthodontic wires' surface texture and friction resistance

    Science.gov (United States)

    Abbassy, Mona Aly

    2016-01-01

    Objectives: The aim of this study was to investigate the effects exerted by the acidulated fluoride gel on stainless steel and nickel-titanium (Ni-Ti) orthodontic wires. Materials and Methods: Sixty stainless steel and Ni-Ti orthodontic archwires were distributed into forty archwires used for in vitro study and twenty for in situ study. Fluoride was applied for 1 h in the in vitro experiment while it was applied for 5 min in the in situ experiment. The friction resistance of all wires with ceramic brackets before/after topical fluoride application was measured using a universal testing machine at 1 min intervals of moving wire. Moreover, surface properties of the tested wires before/after fluoride application and before/after friction test were examined by a scanning electron microscope (SEM). Dunnett's t-test was used to compare frictional resistance of as-received stainless steel wires and Ni-Ti wires to the wires treated by fluoride in vitro and in situ (P < 0.05). Two-way ANOVA was used to compare the effect of fluoride application and type of wire on friction resistance in vitro and in situ (P < 0.05). Results: Ni-Ti wires recorded significantly high friction resistance after fluoride application when compared to stainless steel wires in vitro, P < 0.05. Fluoride application did not significantly affect the friction resistance of the tested wires in situ, P < 0.05. SEM observation revealed deterioration of the surface texture of the Ni-Ti wires after fluoride application in vitro and in situ. Conclusions: The in vitro fluoride application caused an increase in friction resistance of Ni-Ti wires when compared to stainless steel wires. In vitro and in situ fluoride application caused deterioration in surface properties of Ni-Ti wires. PMID:27843886

  2. Submicron Surface-Patterned Fibers and Textiles

    Science.gov (United States)

    2016-11-04

    Submitted to 1 DOI: 10.1002/adma.((please add manuscript number)) Article type : Communication Submicron surface-patterned fibers and...we investigate three specific types of physical forming techniques: milling, laser cutting, and molding (Figure S1). Each method has its unique...semi-crystalline Submitted to 4 polymers, such as polyvinylidene fluoride (PVDF). Conventional molding methods for plastics limit the feature

  3. Effects of surface texturing on the performance of biocompatible UHMWPE as a bearing material during in vitro lubricated sliding/rolling motion.

    Science.gov (United States)

    López-Cervantes, Adrián; Domínguez-López, Iván; Barceinas-Sánchez, José Dolores Oscar; García-García, Adrián Luis

    2013-04-01

    The effect of surface texturing on the performance of biocompatible ultra-high molecular weight polyethylene (UHMWPE) as a bearing material has been investigated using the kinematic range of motions reported for a knee-joint replacement. An experimental apparatus consisting of a ball and a disk rotating independently from each other was used to compare the performance of UHMWPE textured versus plain surfaces, under different combinations of sliding and rolling motion, better known as sliding-to-rolling ratio (SRR). Performance was evaluated through the coefficient of traction of a tribosystem comprising a steel ball on a flat UHMWPE disk and distilled water at 36°C, acting as lubricant. A square array of cavities with diameter D=0.397mm and center-to-center spacing of 1.5D was machined on UHMWPE disks. The experimental design considered two levels for cavity depth, D and D/2, and two for the applied load, 17 and 25N. The SRR was varied from 1 to 11% and the mean speed range was set from 5 to 55mm/s, covering the kinematics and contact pressure conditions of a sauntering cycle on a knee-joint replacement. Stribeck curves of the plain and textured surfaces were obtained and compared against one another. The results demonstrate that the proposed surface pattern reduces the coefficient of traction of the tribological system for the 17N load in the entire kinematic range explored, while for the 25N load the effects were more noticeable at low mean speed and SRR, corresponding to the beginning of motion.

  4. Effect of illuminating and viewing geometry on the color coordinates of samples with various surface textures.

    Science.gov (United States)

    Billmeyer, F W; Marcus, R T

    1969-04-01

    Color measurements with several different illuminating/viewing geometries were carried out for samples with four different surface textures in four different colors: matte papers, glossy papers, ceramic or porcelain enamel tiles, and polished opaque glasses, with ISCC-NBS color designations moderate pink, pale orange-yellow, dark bluish-green, and dark gray. On a single instrument (Cary 14 spectrophotometer), three geometries were used: normal/diffuse (N/D), diffuse/normal (D/N) and normal/45 degrees (N/45). For comparison, measurements were also made on a GE spectrophotometer (GERS) using near-normal/diffuse geometry. All integrating sphere (diffuse) measurements were made with specular component both included and excluded. Specular gloss and goniophotometric reflectance measurements were made. For these samples, the Cary 14 N/D and GERS results are in good agreement, and the results with N/D and D/N geometries are essentially equivalent, but there is strong evidence of the serious problem of incomplete exclusion of the specular component with all of the integrating sphere geometries when operated in the specular-excluded mode, even with samples normally considered to be highly glossy or highly matte.

  5. Excimer laser texturing of natural composite polymer surfaces for studying cell-to-substrate specific response

    Energy Technology Data Exchange (ETDEWEB)

    Dinca, V., E-mail: dincavalentina@yahoo.com [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Alloncle, P.; Delaporte, P. [Aix-Marseille University, CNRS, LP3 Laboratory, Campus de Luminy, 13288 Marseille (France); Ion, V. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Faculty of Physics, University of Bucharest, 077125 Magurele (Romania); Rusen, L.; Filipescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering – IFIN HH, Magurele, Bucharest (Romania); Luculescu, C.; Dinescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest (Romania)

    2015-10-15

    Highlights: • Roughness gradients are obtained in one step by applying single laser pulses and sample tilting. • BSA protein and cell dependence behavior onto gradient characteristics was studied. • The degradation of the samples by lysozyme was correlated to its ability to access the textured area. - Abstract: Surface modifications of biocompatible materials are among the main factors used for enhancing and promoting specific cellular activities (e.g. spreading, adhesion, migration, and differentiation) for various types of medical applications such as implants, microfluidic devices, or tissue engineering scaffolds. In this work an excimer laser at 193 nm was used to fabricate chitosan–collagen roughness gradients. The roughness gradients were obtained in one step by applying single laser pulses and sample tilting. Fourier transform infrared spectroscopy measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectro-ellipsometry (SE) were used for sample characterization. The goal is to determine the optimal morpho-chemical characteristics of these structures for in vitro tailoring of protein adsorption and cell behavior. The response induced by the roughness gradient onto various cell lines (i.e. L 929 fibroblasts, HEP G2 hepatocytes, OLN 93 oligodendrocytes, M63 osteoblasts) and bovine serum albumin (BSA) protein absorption was investigated.

  6. Novel low-cost approach for removal of surface contamination before texturization of commercial monocrystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, U. [Electronics and Telecommunication Engineering Department, IC Design and Fabrication Centre, Jadavpur University, Kolkata 700032 (India); School of Information and Communication Engineering, Sungkyunkwan University, 300, Chun-Chun dong, Jangan-gu, Suwon, 440-746 (Korea); Dhungel, S.K.; Yi, J. [School of Information and Communication Engineering, Sungkyunkwan University, 300, Chun-Chun dong, Jangan-gu, Suwon, 440-746 (Korea); Mondal, A.K. [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 71103 (India); Saha, H. [Electronics and Telecommunication Engineering Department, IC Design and Fabrication Centre, Jadavpur University, Kolkata 700032 (India)

    2007-07-23

    This paper reports a novel approach on the surface treatment of monocrystalline silicon solar cells using an inorganic chemical, sodium hypochlorite (NaOCl) that has some remarkable properties. The treatment of contaminated crystalline silicon wafer with hot NaOCl helps the removal of organic contaminants due to its oxidizing properties. The objective of this paper is to establish the effectiveness of this treatment using hot NaOCl solution before the saw damage removal step of the conventional NaOH texturing approach. A comparative study of surface morphology and FTIR analyses of textured monocrystalline silicon surfaces with and without NaOCl pre-treatment is also reported. The process could result in a significant low cost approach viable for cleaning silicon wafers on a mass production scale. (author)

  7. Texturing of the Silicon Substrate with Nanopores and Si Nanowires for Anti-reflecting Surfaces of Solar Cells

    Directory of Open Access Journals (Sweden)

    A.A. Druzhinin

    2015-06-01

    Full Text Available The paper presents the prospects of obtaining a functional multi-layer anti-reflecting coating of the front surface of solar cells by texturing the surface of the silicon by electrochemical etching. The physical model of the "Black Si" coating with discrete inhomogeneity of the refractive index and technological aspects of producing of "Black Si" functional anti-reflecting coatings were presented. The investigation results of the spectral characteristics of the obtained multilayer multiporous "Black Si" coatings for silicon solar cells made by electrochemical etching are presented. The possibility of creating the texture on a silicon wafer surface using silicon nanowires and ordered nanopores obtained by metal-assisted chemical etching was shown.

  8. Textural evidence for jamming and dewatering of a sub-surface, fluid-saturated granular flow

    Science.gov (United States)

    Sherry, T. J.; Rowe, C. D.; Kirkpatrick, J. D.; Brodsky, E. E.

    2011-12-01

    Sand injectites are spectacular examples of large-scale granular flows involving migration of hundreds of cubic meters of sand slurry over hundreds of meters to kilometers in the sub-surface. By studying the macro- and microstructural textures of a kilometer-scale sand injectite, we interpret the fluid flow regimes during emplacement and define the timing of formation of specific textures in the injected material. Fluidized sand sourced from the Santa Margarita Fm., was injected upward into the Santa Cruz Mudstone, Santa Cruz County, California. The sand injectite exposed at Yellow Bank Beach records emplacement of both hydrocarbon and aqueous sand slurries. Elongate, angular mudstone clasts were ripped from the wall rock during sand migration, providing evidence for high velocity, turbid flow. However, clast long axis orientations are consistently sub-horizontal suggesting the slurry transitioned to a laminar flow as the flow velocity decreased in the sill-like intrusion. Millimeter to centimeter scale laminations are ubiquitous throughout the sand body and are locally parallel to the mudstone clast long axes. The laminations are distinct in exposure because alternating layers are preferentially cemented with limonite sourced from later groundwater infiltration. Quantitative microstructural analyses show that the laminations are defined by subtle oscillations in grain alignment between limonite and non-limonite stained layers. Grain packing, size and shape distributions do not vary. The presence of limonite in alternating layers results from differential infiltration of groundwater, indicating permeability changes between the layers despite minimal grain scale differences. Convolute dewatering structures deform the laminations. Dolomite-cemented sand, a signature of hydrocarbon saturation, forms irregular bodies that cross-cut the laminations and dewatering structures. Laminations are not formed in the dolomite-cemented sand. The relative viscosity difference

  9. Effects of textural and surface characteristics of microporous activated carbons on the methane adsorption capacity at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Bastos-Neto, M. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil); Canabrava, D.V. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil); Torres, A.E.B. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil); Rodriguez-Castellon, E. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, 29071 Malaga (Spain); Jimenez-Lopez, A. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, 29071 Malaga (Spain); Azevedo, D.C.S. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil)]. E-mail: diana@gpsa.ufc.br; Cavalcante, C.L. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil)

    2007-04-30

    The objective of this study is to relate textural and surface characteristics of selected microporous activated carbons to their methane storage capacity. In this work, a magnetic suspension balance (Rubotherm, Germany) was used to measure methane adsorption isotherms of several activated carbon samples. Textural characteristics were assessed by nitrogen adsorption on a regular surface area analyzer (Autosorb-MP, by Quantachrome, USA). N{sub 2} adsorption was analysed by conventional models (BET, DR, HK) and by Monte Carlo molecular simulations. Elemental and surface analyses were performed by X-ray photoelectronic spectroscopy (XPS) for the selected samples. A comparative analysis was then carried out with the purpose of defining some correlation among the variables under study. For the system under study, pore size distribution and micropore volume seem to be a determining factor as long as the solid surface is perfectly hydrophobic. It was concluded that the textural parameters per se do not unequivocally determine natural gas storage capacities. Surface chemistry and methane adsorption equilibria must be taken into account in the decision-making process of choosing an adsorbent for gas storage.

  10. The study of FTO surface texturing fabrication using Argon plasma etching technique for DSSC applications

    Science.gov (United States)

    Jayanti, Lindha; Kusumandari; Sujitno, Tjipto; Suryana, Risa

    2016-02-01

    This paper is aimed to investigate the fabrication of the fluorine-doped tin oxide (FTO) texturing by using Argon (Ar) plasma etching. The pressure and temperature of Ar gas during plasma etching were 1.6 mbar and 240-285oC, respectively. The plasma etching time was varied from 3 and 10 min. We also prepared without etching samples as reference. UV-Vis spectrophotometer showed that the transmittances of etching samples are higher than the without etching samples. The root mean square roughness (Rq) of etching samples are lower than the without etching samples. It is considered that the Ar ions bombardment can modify the FTO surfaces. However, the etching time does not significantly affect the FTO surfaces for 3 min and 10 min. The Rq of the without etching sample, the etching sample for 3 min, and the etching sample for 10 min are 11.697 nm, 9.859 nm, and 9.777 nm, respectively. These results are good agreement with the four point probe measurement that indicated that the sheet resistance (RS) for each the without sample, the etching sample for 3 min, and the etching sample for 10 min are 16.817 Ωsq, 16.067 Ω/sq, and 15.990 Ω/sq. In addition, the optical transmittance of the etching sample for 3 min and the etching sample for 10 min at wavelengths of 350 - 850 nm are almost similar. This is evidence that the etching time below 10 min cannot significantly change the morphology, optical and electrical properties.

  11. Antiferromagnetic textures and dynamics on the surface of a heavy metal

    OpenAIRE

    Zarzuela, Ricardo; Tserkovnyak, Yaroslav

    2017-01-01

    We investigate the formation and dynamics of spin textures in antiferromagnetic insulators adjacent to a heavy-metal substrate with strong spin-orbit interactions. Exchange coupling to conduction electrons engenders an effective anisotropy, Dzyaloshinskii-Moriya interactions, and a magnetoelectric effect for the N\\'{e}el order, which can conspire to produce nontrivial antiferromagnetic textures. Current-driven spin transfer enabled by the heavy metal, furthermore, triggers ultrafast (THz) osc...

  12. Improved adaptability of polyaryl-ether-ether-ketone with texture pattern and graphite-like carbon film for bio-tribological applications

    Science.gov (United States)

    Ren, Siming; Huang, Jinxia; Cui, Mingjun; Pu, Jibin; Wang, Liping

    2017-04-01

    With the development of surface treatment technology, an increasing number of bearings, seals, dynamic friction drive or even biomedical devices involve a textured surface to improve lubrication and anti-wear. The present investigation has been conducted in order to evaluate the friction and wear behaviours of textured polyaryl-ether-ether-ketone (PEEK) coated with a graphite-like carbon (GLC) film sliding against stainless steel pin in biological medium. Compared with pure PEEK, the PEEK coated with GLC film shows excellent tribological performance with a low friction of 0.08 and long lifetime (wear volumes are about 3.78 × 10-4 mm3 for un-textured one and 2.60 × 10-4 mm3 for textured GLC film after 36,000 s of sliding) under physiological saline solution. In particular, the GLC film with appropriate dimple area density is effective to improve friction reduction and wear resistance properties of PEEK substrate under biological solution, which is attributed to the entrapment of wear debris in the dimples to inhibit the graphitization and the fluid dynamic pressure effect derived from the texture surface to increase the thickness in elastohydrodynamic lubrication (EHL) film during sliding motions. Moreover, the friction coefficient of GLC film under physiological saline solution decreases with the increase in the applied load. With the increasing applied load, the texture surface is responsible for accounting the improved wear resistance and a much lower graphitization of the GLC film during whole test.

  13. Transition Texture Synthesis

    Institute of Scientific and Technical Information of China (English)

    Yueh-Yi Lai; Wen-Kai Tai

    2008-01-01

    Synthesis of transition textures is essential for displaying visually acceptable appearances on a terrain. This investigation presents a modified method for synthesizing the transition texture to be tiled on a terrain. All transition pattern types are recognized for a number of input textures. The proposed modified patch-based sampling texture synthesis approach, using the extra feature map of the input source and target textures for patch matching, can synthesize any transition texture on a succession pattern by initializing the output texture using a portion of the source texture enclosed in a transition cut. The transition boundary is further enhanced to improve the visual effect by tracing out the integral texture elements. Either the Game of Life model or Wang tiles method are exploited to present a good-looking profile of successions on a terrain for tiling transition textures. Experimental results indicate that the proposed method requires few input textures, yet synthesizes numerous tileable transition textures, which are useful for obtaining a vivid appearance of a terrain.

  14. Topographic Controls on Spatial Patterns of Soil Texture and Moisture in a Semi-arid Montane Catchment with Aspect-Dependent Vegetation

    Science.gov (United States)

    Lehman, B. M.; Niemann, J. D.

    2008-12-01

    Soil moisture exerts significant control over the partitioning of latent and sensible energy fluxes, the magnitude of both vertical and lateral water fluxes, the physiological and water-use characteristics of vegetation, and nutrient cycling. Considerable progress has been made in determining how soil characteristics, topography, and vegetation influence spatial patterns of soil moisture in humid environments at the catchment, hillslope, and plant scales. However, understanding of the controls on soil moisture patterns beyond the plant scale in semi-arid environments remains more limited. This study examines the relationships between the spatial patterns of near surface soil moisture (upper 5 cm), terrain indices, and soil properties in a small, semi-arid, montane catchment. The 8 ha catchment, located in the Cache La Poudre River Canyon in north-central Colorado, has a total relief of 115 m and an average elevation of 2193 m. It is characterized by steep slopes and shallow, gravelly/sandy soils with scattered granite outcroppings. Depth to bedrock ranges from 0 m to greater than 1 m. Vegetation in the catchment is highly correlated with topographic aspect. In particular, north-facing hillslopes are predominately vegetated by ponderosa pines, while south-facing slopes are mostly vegetated by several shrub species. Soil samples were collected at a 30 m resolution to characterize soil texture and bulk density, and several datasets consisting of more than 300 point measurements of soil moisture were collected using time domain reflectometry (TDR) between Fall 2007 and Summer 2008 at a 15 m resolution. Results from soil textural analysis performed with sieving and the ASTM standard hydrometer method show that soil texture is finer on the north-facing hillslope than on the south-facing hillslope. Cos(aspect) is the best univariate predictor of silts, while slope is the best predictor of coarser fractions up to fine gravel. Bulk density increases with depth but shows no

  15. OUT-OF-FOCUS REGION SEGMENTATION OF 2D SURFACE IMAGES WITH THE USE OF TEXTURE FEATURES

    Directory of Open Access Journals (Sweden)

    K. Anding

    2015-09-01

    Full Text Available A segmentation method of out-of-focus image regions for processed metal surfaces, based on focus textural features is proposed. Such regions contain small amount of useful information. The object of study is a metal surface, which has a cone shape. Some regions of images are blurred because the depth of field of industrial cameras is limited. Automatic removal of out-of-focus regions in such images is one of the possible solutions to this problem. Focus texture features were used to calculate characteristics that describe the sharpness of particular image area. Such features are used in autofocus systems of microscopes and cameras, and their application for segmentation of out-of-focus regions of images is unusual. Thirty-four textural features were tested on a set of metal surface images with out-of-focus regions. The most useful features, usable for segmentation of an image more accurately, are an average grey level and spatial frequency. Proposed segmentation method of out-of-focus image regions for metal surfaces can be successfully applied for evaluation of processing quality of materials with the use of industrial cameras. The method has simple implementation and high calculating speed.

  16. The influence of hierarchical hybrid micro/nano-textured titanium surface with titania nanotubes on osteoblast functions.

    Science.gov (United States)

    Zhao, Lingzhou; Mei, Shenglin; Chu, Paul K; Zhang, Yumei; Wu, Zhifen

    2010-07-01

    Hierarchical hybrid micro/nano-textured titanium surface topographies with titania nanotubes were produced by simple acid etching followed by anodization to mimic the hierarchical structure of bone tissues. Primary rat osteoblasts were used to evaluate the bioactivity. The microtopography formed by acid etching of titanium induced inconsistent osteoblast functions with initial cell adhesion and osteogenesis-related gene expression being dramatically enhanced while other cell behaviors such as proliferation, intracellular total protein synthesis and alkaline phosphatase activity, collagen secretion, and extracellular matrix mineralization being depressed. In comparison, addition of nanotubes to the microtopography led to enhancement of multiple osteoblast functions. Nearly all the cell functions investigated in this study were retained or promoted. Compared to a microtopography, the enhancement of multiple cell functions observed from the hierarchical micro/nano-textured surfaces is expected to lead to faster bone maturation around the titanium implants without compromising the bone mass. In addition, the hierarchical micro/nano-textured surfaces still retain the mechanical interlocking ability of the microtopography thereby boding well for osseointegration. Our study reveals a synergistic role played by the micro and nanotopographies in osteoblast functions and provides insight to the design of better biomedical implant surfaces.

  17. Fabrication of broadband antireflective black metal surfaces with ultra-light-trapping structures by picosecond laser texturing and chemical fluorination

    Science.gov (United States)

    Zheng, Buxiang; Wang, Wenjun; Jiang, Gedong; Mei, Xuesong

    2016-06-01

    A hybrid method consisting of ultrafast laser-assisted texturing and chemical fluorination treatment was applied for efficiently enhancing the surface broadband antireflection to fabricate black titanium alloy surface with ultra-light-trapping micro-nanostructure. Based on the theoretical analysis of surface antireflective principle of micro-nanostructures and fluoride film, the ultra-light-trapping micro-nanostructures have been processed using a picosecond pulsed ultrafast laser on titanium alloy surfaces. Then fluorination treatment has been performed by using fluoroalkyl silane solution. According to X-ray diffraction phase analysis of the surface compositions and measurement of the surface reflectance using spectrophotometer, the broadband antireflective properties of titanium alloy surface with micro-nano structural characteristics were investigated before and after fluorination treatment. The results show that the surface morphology of micro-nanostructures processed by picosecond laser has significant effects on the antireflection of light waves to reduce the surface reflectance, which can be further reduced using chemical fluorination treatment. The high antireflection of over 98 % in a broad spectral range from ultraviolet to infrared on the surface of metal material has been achieved for the surface structures, and the broadband antireflective black metal surfaces with an extremely low reflectance of ultra-light-trapping structures have been obtained in the wavelength range from ultraviolet-visible to near-infrared, middle-wave infrared. The average reflectance of microgroove groups structured surface reaches as low as 2.43 % over a broad wavelength range from 200 to 2600 nm. It indicates that the hybrid method comprising of picosecond laser texturing and chemical fluorination can effectively induce the broadband antireflective black metal surface. This method has a potential application for fabricating antireflective surface used to improve the

  18. Application of local binary pattern and human visual Fibonacci texture features for classification different medical images

    Science.gov (United States)

    Sanghavi, Foram; Agaian, Sos

    2017-05-01

    The goal of this paper is to (a) test the nuclei based Computer Aided Cancer Detection system using Human Visual based system on the histopathology images and (b) Compare the results of the proposed system with the Local Binary Pattern and modified Fibonacci -p pattern systems. The system performance is evaluated using different parameters such as accuracy, specificity, sensitivity, positive predictive value, and negative predictive value on 251 prostate histopathology images. The accuracy of 96.69% was observed for cancer detection using the proposed human visual based system compared to 87.42% and 94.70% observed for Local Binary patterns and the modified Fibonacci p patterns.

  19. The roles of fluid transport and surface reaction in reaction-induced fracturing, with implications for the development of mesh textures in serpentinites

    Science.gov (United States)

    Shimizu, Hiroyuki; Okamoto, Atsushi

    2016-09-01

    The distinct element method was used to simulate chemical-mechanical-hydraulic processes that occur during serpentinization (volume-increasing hydration) within the oceanic lithosphere. The proposed model considers water transported in two ways: advective flow along fractures and through matrices. Variations in fracture pattern and system evolution were examined using two nondimensional parameters: the ratios of the rates of flow in fracture ( Ψ F) and matrix ( Ψ M) to the surface reaction rate. In cases of fixed Ψ F and Ψ M with sufficiently low reaction rates, the fracture pattern is not dependent on the surface reaction rate. Otherwise, the fracture pattern varies systematically as a function of Ψ F and Ψ M. At low Ψ F (≤1) and low Ψ M (≤1), the reaction proceeds from the boundaries inward and forms fine fractures layer by layer. At high Ψ F (≥10,000) and low Ψ M (≤10), the reaction proceeds from the boundaries inward and forms polygonal fracture networks. As Ψ M increases (>100), the reaction tends to proceed homogeneously from the boundaries without fracturing. A comparison of natural and simulated textures reveals that the following conditions are necessary to develop mesh textures during serpentinization in the oceanic lithosphere. (1) The surface reaction rate must be similar to or higher than the fluid flow rate in the matrix (or than the diffusive transport of water), and much lower than the fluid flow rate along fractures. (2) Original olivine grain boundaries act as pathways for fluid transport; these pathways may result from thermal or tectonic stress-induced cracking prior to serpentinization.

  20. Pressure-induced topological insulator in NaBaBi with right-handed surface spin texture

    Science.gov (United States)

    Sun, Yan; Wang, Qing-Ze; Wu, Shu-Chun; Felser, Claudia; Liu, Chao-Xing; Yan, Binghai

    2016-05-01

    Starting from the three-dimensional Dirac semimetal in Na3Bi , we found a topological insulator (TI) in the known compound of NaBaBi by extra pressure. The TI of NaBaBi can be viewed as the distorted version of Na3Bi with breaking inversion symmetry. When the exchange-correlation energy is considered in generalized gradient approximation (GGA), the TI phase has a band inversion between the Bi-p and Na-s orbitals. Since GGA often overestimates the band inversion, we also performed more accurate calculations by using hybrid functional theory (HSE). From HSE calculations we found that NaBaBi exhibits as a trivial insulator at zero pressure, and the other TI phase with p -d inversion can be achieved by pressure. Though both of two TI phases have Dirac-cone-type surface states, they have opposite spin textures. In the upper cone, a lefthanded spin texture exists for the s -p inverted phase (similar to a common TI, e.g., Bi2Se3 ), whereas a righthanded spin texture appears for the p -d inverted phase. This work presents a prototype model of a TI exhibits righthanded spin texture.

  1. Micro- and nano-porous surface patterns prepared by surface-confined directional melt crystallization of solvent

    Science.gov (United States)

    Kim, Byoung Soo; Kim, Hyun Jin; An, Suyeong; Chi, Sangwon; Kim, Junseok; Lee, Jonghwi

    2017-07-01

    Recently, numerous attempts have been made to engineer micro- and nano-porous surface patterns or to develop convenient preparation methods for the practical applications of self-cleaning surfaces, water-repellent surfaces, novel textures, etc. Herein, we introduce a simple, cheap, and repeatable crystallization-based method to produce porous surface structures, on any surface of already fabricated polymeric materials. Contact of the solvent phase with cooled polymer surfaces enabled the limited dissolution of the surfaces and the subsequent extremely fast melt crystallization of the solvent. After removing the crystals, various micro- and nano-porous patterns were obtained, whose pore sizes ranged over three orders of magnitude. Pore depth was linearly dependent on the dissolution time. Crystal growth was mainly directed normal to the surfaces, but it was also controlled in-plane, resulting in cylindrical or lamellar structures. Superhydrophobic surfaces were successfully prepared on both polystyrene and polycarbonate. This process offers a novel surface engineering tool for a variety of polymer surfaces, whose topology can be conveniently controlled over a wide range by crystal engineering.

  2. Study on the tribological properties of the amphiphobic textured metal surface%金属微结构双疏表面的摩擦特性研究

    Institute of Scientific and Technical Information of China (English)

    王莉; 严诚平; 王权岱; 郭方亮; 郝秀清

    2012-01-01

    University of Science and Technology, Wuhan 430074, China) Abstract Microstructure arrays on tin-bronze and bearing steel substrates have been obtained through laser surface texturing technology and then the fluoride treatment on the textured surface was performed, which results in the metal surface with amphiphobic(hydrophobic/oleophobic) property. The tribological properties of the fabricated specimens have been investigated experimentally including the effect of texturing shape, load, and sliding speed. The results show that the textured surfaces could obtain lower friction coefficient than smooth surfaces under the same lubricated conditions and the lowest friction coefficients are 0. 037 and 0. 026 for tin-bronze and bearing steel respectively. Among specimens with various texture shape of surface, the texture with circle shape is optimal for friction reduction. Besides, the effect of the load on friction coefficient varies with the different property of substrate materials. In addition, the friction property of the specimens with various pattern densities on surface shows a visible transition in the same manner from a high-friction coefficient at the lowest speed to lower values then to little higher values as the speed increases, which is consistent with the Stribeck curve in a manner.%通过激光加工在锡青铜(ZQSn6.50.1)和轴承钢(GCr15)表面制备了微结构阵列,并进行低表面能处理,得到了2种金属双疏(疏水/疏油)表面.对制备的试样进行摩擦学性能实验研究,分别考察2种试样表面不同微结构形状、载荷及摩擦速度对其摩擦学性能的影响.结果表明:在相同润滑条件下,锡青铜和轴承钢双疏表面摩擦系数均比各自光滑试样表面低,最低分别为0.037和0.026;2种金属双疏表面具有圆形微凹坑阵列结构时,具有最优的减阻效果;载荷对试件摩擦系数的影响因材料特性不同而不同;随着速度的增加,不同图案密度微结构表面

  3. Computer Texture Mapping for Laser Texturing of Injection Mold

    Directory of Open Access Journals (Sweden)

    Yongquan Zhou

    2014-04-01

    Full Text Available Laser texturing is a relatively new multiprocess technique that has been used for machining 3D curved surfaces; it is more flexible and efficient to create decorative texture on 3D curved surfaces of injection molds so as to improve the surface quality and achieve cosmetic surface of molded plastic parts. In this paper, a novel method of laser texturing 3D curved surface based on 3-axis galvanometer scanning unit has been presented to prevent the texturing of injection mold surface from much distortion which is often caused by traditional texturing processes. The novel method has been based on the computer texture mapping technology which has been developed and presented. The developed texture mapping algorithm includes surface triangulation, notations, distortion measurement, control, and numerical method. An interface of computer texture mapping has been built to implement the algorithm of texture mapping approach to controlled distortion rate of 3D texture math model from 2D original texture applied to curvature surface. Through a case study of laser texturing of a high curvature surface of injection mold of a mice top case, it shows that the novel method of laser texturing meets the quality standard of laser texturing of injection mold.

  4. Functional anatomy of the equine temporomandibular joint: Collagen fiber texture of the articular surfaces.

    Science.gov (United States)

    Adams, K; Schulz-Kornas, E; Arzi, B; Failing, K; Vogelsberg, J; Staszyk, C

    2016-11-01

    In the last decade, the equine masticatory apparatus has received much attention. Numerous studies have emphasized the importance of the temporomandibular joint (TMJ) in the functional process of mastication. However, ultrastructural and histological data providing a basis for biomechanical and histopathological considerations are not available. The aim of the present study was to analyze the architecture of the collagen fiber apparatus in the articular surfaces of the equine TMJ to reveal typical morphological features indicating biomechanical adaptions. Therefore, the collagen fiber alignment was visualized using the split-line technique in 16 adult warmblood horses without any history of TMJ disorders. Within the central two-thirds of the articular surfaces of the articular tubercle, the articular disc and the mandibular head, split-lines ran in a correspondent rostrocaudal direction. In the lateral and medial aspects of these articular surfaces, the split-line pattern varied, displaying curved arrangements in the articular disc and punctual split-lines in the bony components. Mediolateral orientated split-lines were found in the rostral and caudal border of the articular disc and in the mandibular fossa. The complex movements during the equine chewing cycle are likely assigned to different areas of the TMJ. The split-line pattern of the equine TMJ is indicative of a relative movement of the joint components in a preferential rostrocaudal direction which is consigned to the central aspects of the TMJ. The lateral and medial aspects of the articular surfaces provide split-line patterns that indicate movements particularly around a dorsoventral axis.

  5. Histological evaluation of capsules formed by silicon implants coated with polyurethane foam and with a textured surface in rats.

    Science.gov (United States)

    Silva, Eduardo Nascimento; Ribas-Filho, Jurandir Marcondes; Czeczko, Nicolau Gregori; Pachnicki, Jan Pawel Andrade; Netto, Mário Rodrigues Montemor; Lipinski, Leandro Cavalcante; Noronha, Lucia de; Colman, Joelmir; Zeni, João Otavio; Carvalho, Caroline Aragão de

    2016-12-01

    To assess the capsules formed by silicone implants coated with polyurethane foam and with a textured surface. Sixty-four Wistar albinus rats were divided into two groups of 32 each using polyurethane foam and textured surface. The capsules around the implants were analyzed for 30, 50, 70 and 90 days. Were analyzed the following parameters: foreign body reaction, granulation tissue, presence of myofibroblasts, neoangiogenesis, presence of synovial metaplasia, capsular thickness, total area and collagen percentage of type I and III, in capsules formed around silicone implants in both groups. The foreign body reaction was only present in the four polyurethane subgroups. The formation of granulation tissue and the presence of myofibroblasts were higher in the four polyurethane subgroups. Regarding to neoangiogenesis and synovial metaplasia, there was no statistical difference between the groups. Polyurethane group presented (all subgroups) a greater capsule thickness, a smaller total area and collagen percentage of type I and a higher percentage area of type III, with statistical difference. The use of polyurethane-coated implants should be stimulated by the long-term results in a more stable capsule and a lower incidence of capsular contracture, despite developing a more intense and delayed inflammatory reaction in relation to implants with textured surface.

  6. Earth Surface Patterns in 200 Years (Invited)

    Science.gov (United States)

    Werner, B.

    2009-12-01

    What kinds of patterns will characterize Earth's surface in 200 years? This question is addressed using a complex systems dynamical framework for distinct levels of description in a hierarchy, in which time scale and spatial extent increase and number of variables decrease with level, and in which levels are connected nonlinearly to each other via self-organization and slaving and linearly to the external environment. Self-organized patterns linking the present to 200 years in the future must be described dynamically on a level with a time scale of centuries. Human-landscape coupling will play a prominent role in the formation of these patterns as population peaks and interactions become nonlinear over these time scales. Three related examples illustrate this approach. First, the response of human-occupied coastlines to rising sea level. Coastlines in wealthy regions develop a spatially varying boom and bust pattern, with response amplified by structures meant to delay the effects of sea level rise. Coastlines in economically disadvantaged regions experience a subdued response, with populations developing a culture of displacement that minimizes human-landscape interactions in a context of scarce resources. Second, the evolution of nation-state borders with degrading ecosystems, declining resource availability and increasing transportation costs. The maintenance of strong borders as selective filtration systems (goods, capital and people) is based on a cost-benefit analysis in which the economic benefits accruing from long distance, globalized resource exploitation are weighed against policing and infrastructure costs. As costs rise above benefits, borders fragment, with a transition to local barriers and conflicts, and mobile peoples moving to resources. Third, trends in urbanization and development of megacities under economic and environmental stress. The pattern of rapid growth of megacities through inward migration, with displaced people occupying high

  7. Strength of bed nets as function of denier, knitting pattern, texturizing and polymer

    Science.gov (United States)

    2011-01-01

    Background Bursting strength is a standard method for evaluating mosquito net strength. This article suggests that tension strength with one grab and one hook better represent how holes are generated in bed nets in real life. Methods Measurements of bursting strength and tension strengths in the two directions are analysed for eight model nets created for the study. The nets were made in the most commonly used denier (75 and 100 D) and mesh (156 holes/inch2) for multifilament polyester yarns, texturized or not, and with 4 or 6 sided holes. All were made from one polyester quality. Data was arranged in a randomized, complete block design and analysed for significant variables and their interactions. Data was then subjected to regression analyses using net square metre weight as a weighting factor with stepwise removal of variables. This revealed how the four textile variables interacted and allowed for making predictions for the strength of commercial nets in polyester or polyethylene. Results For the model nets, higher denier provided higher bursting strength and tension strengths, texturizing weakened nets and four-sided holes were stronger than six-sided holes. Even when compensating for square metre weight, 100 D nets are stronger than 75 D nets. Results for the commercial polyester net nets are less clear, probably because of different qualities of polyester. Tensile strength: a 75 denier net knitted tightly to provide the same square metre weight as a standard 100 denier net therefore does not obtain the same strength. Polyethylene nets are made of mono-fibre yarns and, therefore, have higher tension strength in both directions than multifilament polyester nets. For bursting strength results overlap for 100 denier yarns of both yarn types. As a class, commercial polyethylene nets are stronger than commercial polyester net whatever method is used for evaluation. Conclusion Tension strength measured in the length and width directions of the net using one hook

  8. Unconventional Fermi surface spin patterns in the (Bi/Pb/Sb)/Ag(111) surface alloy

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Fabian; Dil, Hugo [Physik Institut Universitaet Zuerich (Switzerland); Swiss Light Source PSI (Switzerland); Petrov, Vladimir [Physics Institute St Petersburg (Russian Federation); Patthey, Luc [Swiss Light Source PSI (Switzerland); Osterwalder, Juerg [Physik Institut Universitaet Zuerich (Switzerland)

    2009-07-01

    By a controllable change in the stoichiometry of the long range ordered mixed surface alloy (Bi/Pb/Sb)/Ag(111) the Rashba and Fermi energy can be tuned over a wide range. We show by spin and angle-resolved photoemission spectroscopy that the spin structure of the individual surface state bands remain unaffected despite the random intermixing of the adatoms. We further report on the observation of unconventional Fermi surface spin textures. These spin textures are found when the Fermi energy lies between the crossing point and the apex of the Rashba type Kramer's pair. The results will be discussed in the context of spin transport.

  9. High-speed surface functionalization by direct laser interference patterning (Conference Presentation)

    Science.gov (United States)

    Dyck, Tobias; Lasagni, Andrés.-Fabián.

    2017-03-01

    The material processing by two or more interfering laser beams, is referred to as Direct Laser Interference Patterning (DLIP). The periodic intensity pattern of the overlapping laser beams is used to ablate or modify the material so a functionalization of the surface is achieved. By adjusting the number, direction, intensity and polarization of the interfering beams, the detailed geometry of the intensity pattern can be shaped and the realizable feature sizes can be continuously adjusted within the micro- and submicrometer range. Consequently, the surface texture can be engineered and tailored to perfectly suit the needs of a given application. Typical applications of DLIP range from in- and out coupling of light in solar cells or organic LEDs over improvement of tribological properties in engine parts to security markings and decoration applications due to the shimmering effect of the periodic textures. On laboratory scale, an improvement over unprocessed surfaces has been demonstrated in all of these mentioned applications. However, so far the feed rates have not sufficed to allow an industrial application of the technology. Now, in a joint project of laser manufacturer, optics designer and engineering company, a machine platform has been developed which allows high surface processing speeds in an industrial environment. Feed rates in the range of square meters per minute (corresponding to about one billion features per second) can be achieved. With the help of this platform, DLIP can finally be lifted to industrial application.

  10. Surface electromyography pattern of human swallowing

    Directory of Open Access Journals (Sweden)

    Spadaro Alessandro

    2008-03-01

    Full Text Available Abstract Background The physiology of swallowing is characterized by a complex and coordinated activation of many stomatognathic, pharyngeal, and laryngeal muscles. Kinetics and electromyographic studies have widely investigated the pharyngeal and laryngeal pattern of deglutition in order to point out the differences between normal and dysphagic people. In the dental field, muscular activation during swallowing is believed to be the cause of malocclusion. Despite the clinical importance given to spontaneous swallowing, few physiologic works have studied stomatognathic muscular activation and mandibular movement during spontaneous saliva swallowing. The aim of our study was to investigate the activity patterns of the mandibular elevator muscles (masseter and anterior temporalis muscles, the submental muscles, and the neck muscles (sternocleidomastoid muscles in healthy people during spontaneous swallowing of saliva and to relate the muscular activities to mandibular movement. Methods The spontaneous swallowing of saliva of 111 healthy individuals was analyzed using surface electromyography (SEMG and a computerized kinesiography of mandibular movement. Results Fifty-seven of 111 patients swallowed without occlusal contact (SNOC and 54 individuals had occlusal contact (SOC. The sternocleidomastoid muscles showed a slight, but constant activation during swallowing. The SEMG of the submental and sternocleidomastoid muscles showed no differences between the two groups. The SEMG of the anterior temporalis and masseter muscles showed significant differences (p Conclusion The data suggest that there is not a single "normal" or "typical" pattern for spontaneous saliva swallowing. The polygraph seemed a valuable, simple, non-invasive and reliable tool to study the physiology of swallowing.

  11. Chromatin Fractal Organization, Textural Patterns, and Circularity of Nuclear Envelope in Adrenal Zona Fasciculata Cells.

    Science.gov (United States)

    Pantic, Igor; Nesic, Dejan; Basailovic, Milos; Cetkovic, Mila; Mazic, Sanja; Suzic-Lazic, Jelena; Popevic, Martin

    2016-12-01

    Despite previous research efforts in the fields of histology and cell physiology, the relationship between chromatin structural organization and nuclear shape remains unclear. The aim of this research was to test the existence and strength of correlations between mathematical parameters of chromatin microarchitecture and roundness of the nuclear envelope. On a sample of 240 nuclei of adrenal zona fasciculata cells stained using the DNA-specific Feulgen method, we quantified fractal parameters such as fractal dimension and lacunarity, as well as textural parameters such as angular second moment (ASM), entropy, inverse difference moment, contrast, and variance. Circularity of the nuclear envelope was determined from the nuclear area and perimeter. The results indicate that there is a statistically significant negative correlation between chromatin ASM and circularity. Moreover, there was a statistically significant positive correlation between chromatin fractal dimension and envelope circularity. This is the first study to demonstrate these relationships in adrenal tissue, and also one of the first studies to test the connection between circularity and fractal and gray-level co-occurrence matrix parameters in DNA-specific Feulgen stain. The results could be useful both as an addition to the current knowledge on chromatin/nuclear envelope interactions, and for design of future computer-assisted research software for evaluation of nuclear morphology.

  12. Combined effects of short-term rainfall patterns and soil texture on nitrogen cycling -- A Modeling Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C.; Riley, W.J.

    2009-11-01

    Precipitation variability and magnitude are expected to change in many parts of the world over the 21st century. We examined the potential effects of intra-annual rainfall patterns on soil nitrogen (N) transport and transformation in the unsaturated soil zone using a deterministic dynamic modeling approach. The model (TOUGHREACT-N), which has been tested and applied in several experimental and observational systems, mechanistically accounts for microbial activity, soil-moisture dynamics that respond to precipitation variability, and gaseous and aqueous tracer transport in the soil. Here, we further tested and calibrated the model against data from a precipitation variability experiment in a tropical system in Costa Rica. The model was then used to simulate responses of soil moisture, microbial dynamics, nitrogen (N) aqueous and gaseous species, N leaching, and N trace-gas emissions to changes in rainfall patterns; the effect of soil texture was also examined. The temporal variability of nitrate leaching and NO, N{sub 2}, and N{sub 2}O effluxes were significantly influenced by rainfall dynamics. Soil texture combined with rainfall dynamics altered soil moisture dynamics, and consequently regulated soil N responses to precipitation changes. The clay loam soil more effectively buffered water stress during relatively long intervals between precipitation events, particularly after a large rainfall event. Subsequent soil N aqueous and gaseous losses showed either increases or decreases in response to increasing precipitation variability due to complex soil moisture dynamics. For a high rainfall scenario, high precipitation variability resulted in as high as 2.4-, 2.4-, 1.2-, and 13-fold increases in NH{sub 3}, NO, N{sub 2}O and NO{sub 3}{sup -} fluxes, respectively, in clay loam soil. In sandy loam soil, however, NO and N{sub 2}O fluxes decreased by 15% and 28%, respectively, in response to high precipitation variability. Our results demonstrate that soil N cycling

  13. The influence of surface texture and wettability on initial bacterial adhesion on titanium and zirconium oxide dental implants.

    Science.gov (United States)

    Wassmann, Torsten; Kreis, Stefan; Behr, Michael; Buergers, Ralf

    2017-12-01

    This study aims to investigate bacterial adhesion on different titanium and ceramic implant surfaces, to correlate these findings with surface roughness and surface hydrophobicity, and to define the predominant factor for bacterial adhesion for each material. Zirconia and titanium specimens with different surface textures and wettability (5.0 mm in diameter, 1.0 mm in height) were prepared. Surface roughness was measured by perthometer (R a ) and atomic force microscopy, and hydrophobicity according to contact angles by computerized image analysis. Bacterial suspensions of Streptococcus sanguinis and Staphylococcus epidermidis were incubated for 2 h at 37 °C with ten test specimens for each material group and quantified with fluorescence dye CytoX-Violet and an automated multi-detection reader. Variations in surface roughness (R a ) did not lead to any differences in adhering S. epidermidis, but higher R a resulted in increased S. sanguinis adhesion. In contrast, higher bacterial adhesion was observed on hydrophobic surfaces than on hydrophilic surfaces for S. epidermidis but not for S. sanguinis. The potential to adhere S. sanguinis was significantly higher on ceramic surfaces than on titanium surfaces; no such preference could be found for S. epidermidis. Both surface roughness and wettability may influence the adhesion properties of bacteria on biomaterials; in this context, the predominant factor is dependent on the bacterial species. Wettability was the predominant factor for S. epidermidis and surface texture for S. sanguinis. Zirconia did not show any lower bacterial colonization potential than titanium. Arithmetical mean roughness values R a (measured by stylus profilometer) are inadequate for describing surface roughness with regard to its potential influence on microbial adhesion.

  14. Is It Possible to Classify Topsoil Texture Using a Sensor Located 800 km Away from the Surface?

    Directory of Open Access Journals (Sweden)

    José Alexandre Melo Demattê

    Full Text Available ABSTRACT It is often difficult for pedologists to “see” topsoils indicating differences in properties such as soil particle size. Satellite images are important for obtaining quick information for large areas. However, mapping extensive areas of bare soil using a single image is difficult since most areas are usually covered by vegetation. Thus, the aim of this study was to develop a strategy to determine bare soil areas by fusing multi-temporal satellite images and classifying them according to soil textures. Three different areas located in two states in Brazil, with a total of 65,000 ha, were evaluated. Landsat images of a specific dry month (September over five consecutive years were collected, processed, and subjected to atmospheric correction (values in surface reflectance. Non-vegetated areas were discriminated from vegetated ones using the Linear Spectral Mixture Model (LSMM and Normalized Difference Vegetation Index (NDVI. Thus, we were able to fuse images with only bare soil. Field samples were taken from bare soil pixel areas. Pixels of soils with different textures (soil texture classifications were used for supervised classification in which all areas with exposed soil were classified. Single images reached an average of 36 % bare soil, where the mapper could only “see” these points. After using the proposed methodology, we reached a maximum of 85 % in bare areas; therefore, a pedologist would have proper conditions for generating a continuous map of spatial variations in soil properties. In addition, we mapped soil textural classes with accuracy up to 86.7 % for clayey soils. Overall accuracy was 63.8 %. The method was tested in an unknown area to validate the accuracy of our classification method. Our strategy allowed us to discriminate and categorize different soil textures in the field with 90 % accuracy using images. This method can assist several professionals in soil science, from pedologists to mappers of soil

  15. Texturing in titanium grade 2 surface irradiate with ultrashort pulse laser; Texturizacao em superficies de titanio grau 2 irradiadas com laser com pulsos ultracurtos

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Alessandro Francelino

    2015-07-01

    The texturing laser micromachining is an important alternative to improve the bonding adhesion between composites and titanium, which are applied to structural components in the aerospace industry. The texturing running on titanium plates is due to the fact that the preferred joining technique for many composite materials is the adhesive bonding. In this work, titanium plates were texturized using laser ultrashort pulses temporal widths of femtoseconds. This process resulted in minimal heat transfer to the material, avoiding deformation of the titanium plate surface as well as the formation of resolidified material in the ablated region. These drawbacks have occurred with the use of nanoseconds pulses. Were performed three types of texturing using laser with femtosecond pulses, with variations in the distances between the machined lines. The analysis of the obtained surfaces found that the wettability increases when there is the increased distance between the texturing lines. Advancing in the analysis by optical profilometry of textured surfaces was observed that there is substantial increase in the volume available for penetration of structural adhesive when the distances between the textured lines are diminished. In tensile tests conducted it was observed that there is an increase in shear strength of the adhesive joint by reducing the distance between the textured lines. (author)

  16. Surface characteristics of debris-covered glacier tongues in the Khumbu Himalaya derived from remote sensing texture analysis

    Science.gov (United States)

    Racoviteanu, Adina; Arnaud, Yves; Nicholson, Lindsay

    2013-04-01

    The delineation of debris-covered glaciers remains a challenge in optical remote sensing, due to the similarity of the spectral signature of debris-covered ice to surrounding lateral moraines, making it difficult to apply standard semi-automated algorithms commonly used for clean ice delineation. Furthermore, supraglacial debris exhibits considerable spatial variability in its characteristics such as debris cover thickness, particle size, thermal resistance and thermal conductivity. These properties are needed in order to map the extent of debris cover and to estimate ice melt under the debris cover or at the surface. In this study we evaluate the potential of texture analysis for detecting surface characteristics of debris-cover glacier tongues in the Khumbu Himalaya, using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and high-resolution Ikonos data. We focus on mapping supra-glacier lakes and exposed ice walls using texture analysis algorithms such as grey-level co-occurrence measures (GLCM), filtering, image segmentation, and particle boundaries. We compare the performance of various existing commercial software suitable for texture analysis such as ERDAS Objective, Aphelion, as well as public domain image display and analysis software used originally for medical analysis, notably Image SXM and ImageJ. Preliminary results based on geostatistics and GLCM measures show differences in surface roughness of debris cover when compared to surrounding ice-free moraines. We expand on these results and aim at developing a quasi-automated algorithm for extracting surface features, which will be used as input in an energy balance model for estimating melting under debris cover as well as surface ice melt.

  17. Surface electromyography pattern of human swallowing.

    Science.gov (United States)

    Monaco, Annalisa; Cattaneo, Ruggero; Spadaro, Alessandro; Giannoni, Mario

    2008-03-26

    The physiology of swallowing is characterized by a complex and coordinated activation of many stomatognathic, pharyngeal, and laryngeal muscles. Kinetics and electromyographic studies have widely investigated the pharyngeal and laryngeal pattern of deglutition in order to point out the differences between normal and dysphagic people. In the dental field, muscular activation during swallowing is believed to be the cause of malocclusion.Despite the clinical importance given to spontaneous swallowing, few physiologic works have studied stomatognathic muscular activation and mandibular movement during spontaneous saliva swallowing.The aim of our study was to investigate the activity patterns of the mandibular elevator muscles (masseter and anterior temporalis muscles), the submental muscles, and the neck muscles (sternocleidomastoid muscles) in healthy people during spontaneous swallowing of saliva and to relate the muscular activities to mandibular movement. The spontaneous swallowing of saliva of 111 healthy individuals was analyzed using surface electromyography (SEMG) and a computerized kinesiography of mandibular movement. Fifty-seven of 111 patients swallowed without occlusal contact (SNOC) and 54 individuals had occlusal contact (SOC). The sternocleidomastoid muscles showed a slight, but constant activation during swallowing. The SEMG of the submental and sternocleidomastoid muscles showed no differences between the two groups. The SEMG of the anterior temporalis and masseter muscles showed significant differences (p swallowing was significantly higher in the SNOC subjects. Gender and age were not related to electromyographic activation. Healthy SOC and SNOC behaved in different ways. The data suggest that there is not a single "normal" or "typical" pattern for spontaneous saliva swallowing. The polygraph seemed a valuable, simple, non-invasive and reliable tool to study the physiology of swallowing.

  18. Nanosecond laser texturing of uniformly and non-uniformly wettable micro structured metal surfaces for enhanced boiling heat transfer

    Science.gov (United States)

    Zupančič, Matevž; Može, Matic; Gregorčič, Peter; Golobič, Iztok

    2017-03-01

    Microstructured uniformly and non-uniformly wettable surfaces were created on 25-μm-thin stainless steel foils by laser texturing using a marking nanosecond Nd:YAG laser (λ = 1064 nm) and utilizing various laser fluences and scan line separations. High-speed photography and high-speed IR thermography were used to investigate nucleate boiling heat transfer on the microstructured surfaces. The most pronounced results were obtained on a surface with non-uniform microstructure and non-uniform wettability. The obtained results show up to a 110% higher heat transfer coefficients and 20-40 times higher nucleation site densities compared to the untextured surface. We show that the number of active nucleation sites is significantly increased in the vicinity of microcavities that appeared in areas with the smallest (10 μm) scan line separation. Furthermore, this confirms the predictions of nucleation criteria and proves that straightforward, cost-effective nanosecond laser texturing allows the production of cavities with diameters of up to a few micrometers and surfaces with non-uniform wettability. Additionally, this opens up important possibilities for a more deterministic control over the complex boiling process.

  19. Bio-inspired design of ice-retardant devices based on benthic marine invertebrates: the effect of surface texture

    CERN Document Server

    Mehrabani, Homayun; Tse, Kyle; Evangelista, Dennis

    2014-01-01

    Growth of ice on surfaces poses a challenge for both organisms and for devices that come into contact with liquids below the freezing point. Resistance of some organisms to ice formation and growth, either in subtidal environments (e.g. Antarctic anchor ice), or in environments with moisture and cold air (e.g. plants, intertidal) begs examination of how this is accomplished. Several factors may be important in promoting or mitigating ice formation. As a start, here we examine the effect of surface texture alone. We tested four candidate surfaces, inspired by hard-shelled marine invertebrates and constructed using a three-dimensional printing process. We screened biological and artifical samples for ice formation and accretion in submerged conditions using previous methods, and developed a new test to examine ice formation from surface droplets as might be encountered in environments with moist, cold air. It appears surface texture plays only a small role in delaying the onset of ice formation: a stripe featur...

  20. Protein surface patterning using nanoscale PEG hydrogels.

    Science.gov (United States)

    Hong, Ye; Krsko, Peter; Libera, Matthew

    2004-12-01

    We have used focused electron-beam cross-linking to create nanosized hydrogels and thus present a new method with which to bring the attractive biocompatibility associated with macroscopic hydrogels into the submicron length-scale regime. Using amine-terminated poly(ethylene glycol) thin films on silicon substrates, we generate nanohydrogels with lateral dimensions of order 200 nm which can swell by a factor of at least five, depending on the radiative dose. With the focused electron beam, high-density arrays of such nanohydrogels can be flexibly patterned onto silicon surfaces. Significantly, the amine groups remain functional after e-beam exposure, and we show that they can be used to covalently bind proteins and other molecules. We use bovine serum albumin to amplify the number of amine groups, and we further demonstrate that different proteins can be covalently bound to different hydrogel pads on the same substrate to create multifunctional surfaces useful in emerging bio/proteomic and sensor technologies.

  1. Electrochemically grown rough-textured nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Pawan; Postetter, David; Saragnese, Daniel [Johns Hopkins University, Department of Chemical and Biomolecular Engineering (United States); Papadakis, Stergios J. [Johns Hopkins University, Applied Physics Laboratory (United States); Gracias, David H., E-mail: dgracias@jhu.ed [Johns Hopkins University, Department of Chemical and Biomolecular Engineering (United States)

    2010-03-15

    Nanowires with a rough surface texture show unusual electronic, optical, and chemical properties; however, there are only a few existing methods for producing these nanowires. Here, we describe two methods for growing both free standing and lithographically patterned gold (Au) nanowires with a rough surface texture. The first strategy is based on the deposition of nanowires from a silver (Ag)-Au plating solution mixture that precipitates an Ag-Au cyanide complex during electrodeposition at low current densities. This complex disperses in the plating solution, thereby altering the nanowire growth to yield a rough surface texture. These nanowires are mass produced in alumina membranes. The second strategy produces long and rough Au nanowires on lithographically patternable nickel edge templates with corrugations formed by partial etching. These rough nanowires can be easily arrayed and integrated with microscale devices.

  2. Analysis of image versus position, scale and direction reveals pattern texture anisotropy

    Directory of Open Access Journals (Sweden)

    Roland eLehoucq

    2015-01-01

    Full Text Available Pattern heterogeneities and anisotropies often carry significant physical information. We provide a toolbox which: (i cumulates analysis in terms of position, direction and scale; (ii is as general as possible; (iii is simple and fast to understand, implement, execute and exploit.It consists in dividing the image into analysis boxes at a chosen scale; in each box an ellipse (the inertia tensor is fitted to the signal and thus determines the direction in which the signal is more present. This tensor can be averaged in position and/or be used to study the dependence with scale. This choice is formally linked with Leray transforms and anisotropic wavelet analysis. Such protocol is intutively interpreted and consistent with what the eye detects: relevant scales, local variations in space, priviledged directions. It is fast and parallelizable.Its several variants are adaptable to the user's data and needs. It is useful to statistically characterize anisotropies of 2D or 3D patterns in which individual objects are not easily distinguished, with only minimal pre-processing of the raw image, and more generally applies to data in higher dimensions.It is less sensitive to edge effects, and thus better adapted for a multiscale analysis down to small scale boxes, than pair correlation function or Fourier transform.Easy to understand and implement,it complements more sophisticated methods such as Hough transform or diffusion tensor imaging.We use it on various fracture patterns (sea ice cover, thin sections of granite, granular materials, to pinpoint the maximal anisotropy scales. The results are robust to noise and to user choices. This toolbox could turn also useful for granular materials, hard condensed matter, geophysics, thin films, statistical mechanics, characterisation of networks, fluctuating amorphous systems, inhomogeneous and disordered systems, or medical imaging, among others.

  3. Deep Filter Banks for Texture Recognition, Description, and Segmentation.

    Science.gov (United States)

    Cimpoi, Mircea; Maji, Subhransu; Kokkinos, Iasonas; Vedaldi, Andrea

    Visual textures have played a key role in image understanding because they convey important semantics of images, and because texture representations that pool local image descriptors in an orderless manner have had a tremendous impact in diverse applications. In this paper we make several contributions to texture understanding. First, instead of focusing on texture instance and material category recognition, we propose a human-interpretable vocabulary of texture attributes to describe common texture patterns, complemented by a new describable texture dataset for benchmarking. Second, we look at the problem of recognizing materials and texture attributes in realistic imaging conditions, including when textures appear in clutter, developing corresponding benchmarks on top of the recently proposed OpenSurfaces dataset. Third, we revisit classic texture represenations, including bag-of-visual-words and the Fisher vectors, in the context of deep learning and show that these have excellent efficiency and generalization properties if the convolutional layers of a deep model are used as filter banks. We obtain in this manner state-of-the-art performance in numerous datasets well beyond textures, an efficient method to apply deep features to image regions, as well as benefit in transferring features from one domain to another.

  4. Texture coding in the rat whisker system: slip-stick versus differential resonance.

    Directory of Open Access Journals (Sweden)

    Jason Wolfe

    2008-08-01

    Full Text Available Rats discriminate surface textures using their whiskers (vibrissae, but how whiskers extract texture information, and how this information is encoded by the brain, are not known. In the resonance model, whisker motion across different textures excites mechanical resonance in distinct subsets of whiskers, due to variation across whiskers in resonance frequency, which varies with whisker length. Texture information is therefore encoded by the spatial pattern of activated whiskers. In the competing kinetic signature model, different textures excite resonance equally across whiskers, and instead, texture is encoded by characteristic, nonuniform temporal patterns of whisker motion. We tested these models by measuring whisker motion in awake, behaving rats whisking in air and onto sandpaper surfaces. Resonant motion was prominent during whisking in air, with fundamental frequencies ranging from approximately 35 Hz for the long Delta whisker to approximately 110 Hz for the shorter D3 whisker. Resonant vibrations also occurred while whisking against textures, but the amplitude of resonance within single whiskers was independent of texture, contradicting the resonance model. Rather, whiskers resonated transiently during discrete, high-velocity, and high-acceleration slip-stick events, which occurred prominently during whisking on surfaces. The rate and magnitude of slip-stick events varied systematically with texture. These results suggest that texture is encoded not by differential resonant motion across whiskers, but by the magnitude and temporal pattern of slip-stick motion. These findings predict a temporal code for texture in neural spike trains.

  5. Neuronal encoding of texture in the whisker sensory pathway.

    Directory of Open Access Journals (Sweden)

    Ehsan Arabzadeh

    2005-01-01

    Full Text Available A major challenge of sensory systems neuroscience is to quantify brain activity underlying perceptual experiences and to explain this activity as the outcome of elemental neuronal response properties. Rats make extremely fine discriminations of texture by "whisking" their vibrissae across an object's surface, yet the neuronal coding underlying texture sensations remains unknown. Measuring whisker vibrations during active whisking across surfaces, we found that each texture results in a unique "kinetic signature" defined by the temporal profile of whisker velocity. We presented these texture-induced vibrations as stimuli while recording responses of first-order sensory neurons and neurons in the whisker area of cerebral cortex. Each texture is encoded by a distinctive, temporally precise firing pattern. To look for the neuronal coding properties that give rise to texture-specific firing patterns, we delivered horizontal and vertical whisker movements that varied randomly in time ("white noise" and found that the response probabilities of first-order neurons and cortical neurons vary systematically according to whisker speed and direction. We applied the velocity-tuned spike probabilities derived from white noise to the sequence of velocity features in the texture to construct a simulated texture response. The close match between the simulated and real responses indicates that texture coding originates in the selectivity of neurons to elemental kinetic events.

  6. Contrast negation and texture synthesis differentially disrupt natural texture appearance.

    Science.gov (United States)

    Balas, Benjamin

    2012-01-01

    Natural textures have characteristic image statistics that make them discriminable from unnatural textures. For example, both contrast negation and texture synthesis alter the appearance of natural textures even though each manipulation preserves some features while disrupting others. Here, we examined the extent to which contrast negation and texture synthesis each introduce or remove critical perceptual features for discriminating unnatural textures from natural textures. We find that both manipulations remove information that observers use for distinguishing natural textures from transformed versions of the same patterns, but do so in different ways. Texture synthesis removes information that is relevant for discrimination in both abstract patterns and ecologically valid textures, and we also observe a category-dependent asymmetry for identifying an "oddball" real texture among synthetic distractors. Contrast negation exhibits no such asymmetry, and also does not impact discrimination performance in abstract patterns. We discuss our results in the context of the visual system's tuning to ecologically relevant patterns and other results describing sensitivity to higher-order statistics in texture patterns.

  7. Iron oxide porous nanorods with different textural properties and surface composition: Preparation, characterization and electrochemical lithium storage capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Tartaj, Pedro; Amarilla, Jose M. [Instituto de Ciencia de Materiales de Madrid (CSIC), Campus Universitario de Cantoblanco, 28049, Madrid (Spain)

    2011-02-15

    We here report a method for the facile and large scale preparation of lithium-ion battery anodes based on {alpha}-Fe{sub 2}O{sub 3} (hematite) nanorods with different textural characteristics and surface composition. The method combines electrostatically driven self-assembly approaches with specific adsorption and magnetically easy to disrupt soft aggregates. Special emphasis has been set to correlate the textural characteristics (porosity) and surface composition (core, core-nanoshell and core-double nanoshells) of nanorods with their electrochemical response. Thus, we have shown that nanorods present a nanophase whose specific capacity strongly depends on the lithium transport distances (nanorods with slit-shape mesopores running along their long axis vs. non-porous or surface blocked nanorods). We have also shown that the capacity retention of this nanophase after several charge-discharge processes depends on maintaining the structural integrity of the nanorods. Essential for the success of this latter study has been the use of nanorods that offer a simple tool (oriented X-ray line broadening) to follow their electrochemical grinding. Our data suggest that {alpha}-Fe{sub 2}O{sub 3} mesoporous nanorods could both operate at a voltage and retain a capacity similar to that of nanostructured lithium titanates anodes if actions are taken to prevent electrochemical grinding. (author)

  8. Investigation of the Influence of Shapes-Texture on Surface Deformation of UHMWPE as a Bearing Material in Static Normal Load and Rolling Contact

    Science.gov (United States)

    Lestari, W. D.; Ismail, R.; Jamari, J.; Bayuseno, A. P.

    2017-05-01

    Surface texture is a common method for improving wear properties of a tribo-pair of soft and hard bearing material. The reduction of wear rates on the contacting surface material is becoming important issues. In the present study, analysis of the contact pressure on the flat surface of UHMWPE (Ultra High Molecular Weight Polyethylene) under the static- and rolling motion with the surface of steel ball used the 3D finite element method (FEM) (the ABAQUS software version 6.12). Five shaped-texture models (square, circle, ellipse, triangle, and chevron) were presented on the flat surface for analysis. The normal load of 17, 30 and 50 N was deliberately set-up for static and rolling contact analysis. The contact pressure was determined to predict the wear behavior of the shaped-texture on the flat surface of UHMWPE. The results have shown that the static normal load yielded the lowest von-Mises stress distribution on the shaped-texture of the ellipse for all values applied a load, while the square shape experienced the highest stress distribution. Under rolling contact, however, the increasing load yielded the increasing von Mises stress distribution for the texture with a triangle shape. Moreover, the texture shapes for circle, ellipse, and chevron respectively, may undergo the lowest stress distribution for all load. The wear calculation provided that the circle and square shape may undergo the highest wear rates. Obviously, the surface texture of circle, ellipse, and chevron may experience the lowest wear rates and is potential for use in the surface engineering of bearing materials.

  9. Surface nano-texturing of silicon by picosecond laser irradiation through TiO2 nanotube arrays

    Science.gov (United States)

    Babu, K. E. Sarath Raghavendra; Duraiselvam, Muthukannan

    2015-10-01

    This article presents, nano-texturing of crystalline silicon by irradiating picosecond laser with variable spatial intensity, caused by optically non-linear TiO2 nanotube arrays (TNTA). Along with micro-scale surface structure, highly ordered laser-induced periodic surface structures (LIPSS) was observed at nano-scale. The periodicity (Λ) of the LIPSS generated was near to the laser wavelength (532 nm). Surface morphology at micro-level was characterized by optical microscopy (OM) and white light interferometer (WLI) and at the nano-scale by scanning electron microscope (SEM) and atomic force microscope (AFM). The results highlight the potential use of TNTA as a single step process to produce micro/nanostructures without any gas/liquid medium under ambient condition.

  10. Adsorption of dyes by ACs prepared from waste tyre reinforcing fibre. Effect of texture, surface chemistry and pH.

    Science.gov (United States)

    Acevedo, Beatriz; Rocha, Raquel P; Pereira, Manuel F R; Figueiredo, José L; Barriocanal, Carmen

    2015-12-01

    This paper compares the importance of the texture and surface chemistry of waste tyre activated carbons in the adsorption of commercial dyes. The adsorption of two commercial dyes, Basic Astrazon Yellow 7GLL and Reactive Rifafix Red 3BN on activated carbons made up of reinforcing fibres from tyre waste and low-rank bituminous coal was studied. The surface chemistry of activated carbons was modified by means of HCl-HNO3 treatment in order to increase the number of functional groups. Moreover, the influence of the pH on the process was also studied, this factor being of great importance due to the amphoteric characteristics of activated carbons. The activated carbons made with reinforcing fibre and coal had the highest SBET, but the reinforcing fibre activated carbon samples had the highest mesopore volume. The texture of the activated carbons was not modified upon acid oxidation treatment, unlike their surface chemistry which underwent considerable modification. The activated carbons made with a mixture of reinforcing fibre and coal experienced the largest degree of oxidation, and so had more acid surface groups. The adsorption of reactive dye was governed by the mesoporous volume, whilst surface chemistry played only a secondary role. However, the surface chemistry of the activated carbons and dispersive interactions played a key role in the adsorption of the basic dye. The adsorption of the reactive dye was more favored in a solution of pH 2, whereas the basic dye was adsorbed more easily in a solution of pH 12. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Determination of crystal grain orientations by optical microscopy at textured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lausch, D.; Gläser, M.; Hagendorf, C. [Team Mikrostrukturdiagnostik und Analytik, Fraunhofer-Center für Silizium-Photovoltaik CSP, Walter-Hülse-Straße 1 Halle (Saale), Sachsen-Anhalt D-06120 (Germany)

    2013-11-21

    In this contribution, a new method to determine the crystal orientation with the example of chemical treated silicon wafers by means of optical microscopy has been demonstrated. The introduced procedure represents an easy method to obtain all relevant parameters to describe the crystal structure of the investigated material, i.e., the crystal grain orientation and the grain boundary character. The chemical treatment is a standard mono-texture for solar cells, well known in the solar industry. In general, this concept can also be applied to other crystalline materials, i.e., GaAs, SiC, etc., the only thing that needs to be adjusted is the texturing method to reveal specific crystal planes and the calculation model. In conclusion, an application of this method is shown with the example of the defect classification of recombination active defects in mc-Si solar cell. The introduced method demonstrates a simple and quick opportunity to improve the crystallization process and the quality of electronic devices by means of an optical microscope and a chemical treatment of the material.

  12. Design of fabric texture pattern based on digital printing technology%基于数码印花技术纺织面料肌理图案设计

    Institute of Scientific and Technical Information of China (English)

    梁惠娥; 张冠峰; 王潮霞

    2013-01-01

    Using digital printing as a technical support,texture pattern design was analyzed based on the morphological feature of texture pattern and the pattern design principle of digital ink-jet printing of fabrics.The paper discussed the advantages of application of the digital inkjet printing technique to the texture pattern design,including the widening of color gamut,improvement of pattern color effect,the increase of flexibility of pattern design,and the benefit for expression of design concepts of designers.The design principle and general rule of texture pattern design of fabrics using digital printing technology were presented via the analysis of the texture form and the characteristics of computer texture pattern design.The repeated permutation,gradual change and multiplicity combination of texture structure were conducted by means of summarization,abstraction and decomposition.Texture pattern was then applied to the print pattern design of fabrics reasonably so as to satisfy aesthetic taste of modern consumers who pursuit individual character.It also improved the added value and increased the variety of digital printed products.%以数码印花作为技术支撑,结合肌理图案的形态特征和纺织面料数字喷墨印花图案设计原则对肌理图案设计进行分析,提出了数字喷墨印花技术在肌理图案设计中对于肌理色彩和结构等表现手法上的优势,扩展了肌理图案的色域,改善了图案的色彩效果,增添了图案的灵活性,更加方便了设计师设计理念的表达和展现.结合对肌理图案形式的分析和现代计算机肌理图案设计特点提出了纺织面料数码印花肌理图案的设计原则和一般规律,通过概括、提炼、分解等手法将肌理的组织结构进行重复排列、渐变和多样组合,进而将肌理图案合理的运用于纺织面料印花图案设计中,增加产品附加值,扩充数码印花产品种类,满足现代消费者追求个性的审美品味.

  13. Deposition of Ultrathin Nano-Hydroxyapatite Films on Laser Micro-Textured Titanium Surfaces to Prepare a Multiscale Surface Topography for Improved Surface Wettability/Energy

    Directory of Open Access Journals (Sweden)

    Maria Surmeneva

    2016-10-01

    Full Text Available The primary aim of this study was to analyse the correlation between topographical features and chemical composition with the changes in wettability and the surface free energy of microstructured titanium (Ti surfaces. Periodic microscale structures on the surface of Ti substrates were fabricated via direct laser interference patterning (DLIP. Radio-frequency magnetron sputter deposition of ultrathin nanostructured hydroxyapatite (HA films was used to form an additional nanoscale grain morphology on the microscale-structured Ti surfaces to generate multiscale surface structures. The surface characteristics were evaluated using atomic force microscopy and contact angle and surface free energy measurements. The structure and phase composition of the HA films were investigated using X-ray diffraction. The HA-coated periodic microscale structured Ti substrates exhibited a significantly lower water contact angle and a larger surface free energy compared with the uncoated Ti substrates. Control over the wettability and surface free energy was achieved using Ti substrates structured via the DLIP technique followed by the deposition of a nanostructured HA coating, which resulted in the changes in surface chemistry and the formation of multiscale surface topography on the nano- and microscale.

  14. Effects of texture component orientation on orientation flow visibility for 3-D shape perception.

    Science.gov (United States)

    Fowler, Michelle L; Li, Andrea

    2013-01-01

    In images of textured 3-D surfaces, orientation flows created by the texture components parallel to the surface slant play a critical role in conveying the surface slant and shape. This study examines the visibility of these orientation flows in complex patterns. Specifically, we examine the effect of orientation of neighboring texture components on orientation flow visibility. Complex plaids consisting of gratings equally spaced in orientation were mapped onto planar and curved surfaces. The visibility of the component that creates the orientation flows was quantified by measuring its contrast threshold (CT) while varying the combination of neighboring components present in the pattern. CTs were consistently lowest only when components closest in orientation to that of the orientation flows were subtracted from the pattern. This finding suggests that a previously reported frequency-selective cross-orientation suppression mechanism involved with the perception of 3-D shape from texture is affected by proximity in orientation of concurrent texture components.

  15. Effects of texture component orientation on orientation flow visibility for 3-D shape perception.

    Directory of Open Access Journals (Sweden)

    Michelle L Fowler

    Full Text Available In images of textured 3-D surfaces, orientation flows created by the texture components parallel to the surface slant play a critical role in conveying the surface slant and shape. This study examines the visibility of these orientation flows in complex patterns. Specifically, we examine the effect of orientation of neighboring texture components on orientation flow visibility. Complex plaids consisting of gratings equally spaced in orientation were mapped onto planar and curved surfaces. The visibility of the component that creates the orientation flows was quantified by measuring its contrast threshold (CT while varying the combination of neighboring components present in the pattern. CTs were consistently lowest only when components closest in orientation to that of the orientation flows were subtracted from the pattern. This finding suggests that a previously reported frequency-selective cross-orientation suppression mechanism involved with the perception of 3-D shape from texture is affected by proximity in orientation of concurrent texture components.

  16. Evaporation of elongated droplets on chemically stripe-patterned surfaces

    NARCIS (Netherlands)

    Jansen, H.P.; Zandvliet, H.J.W.; Kooij, E.S.

    2015-01-01

    We investigate the evaporation of elongated droplets on chemically striped patterned surfaces. Variation of elongation is achieved by depositing droplets on surfaces with varying ratios of hydrophobic and hydrophilic stripe widths. Elongated droplets evaporate faster than more spherical droplets. Bo

  17. Pattern design on 3D triangular garment surfaces

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper focuses on a pattern design method for a 3D triangular garment surface. Firstly, some definitions of 3D style lines are proposed for designing the boundaries of patterns as drawing straight lines or splines on the triangular surface.Additionally some commonly used style lines are automatically generated to enhance design efficiency. Secondly, after style lines are preprocessed, a searching method is presented for quickly obtaining the boundaries and patches of a pattern on the 3D triangular surface. Finally a new pattern design reuse method is introduced by encoding/decoding the style line information. After style lines are encoded, the pattern design information can be saved in a pattern template and when decoding this template on a new garment surface, it automates the pattern generation for made-to-measure apparel products.

  18. Configuration effects on texture transparency.

    Science.gov (United States)

    Kawabe, Takahiro; Miura, Kayo

    2004-01-01

    This study examined the factors producing the perception of transparency between overlaid regions composed of Gabor micro-patterns as functions of their spatial frequency, separation of overlaid regions, and types of orientation modulation. The results showed that the likelihood of perceiving transparency was high both when (1) the difference in Gabor spatial frequency between regions was large, and (2) the region boundary, which was formed by short-range orientation differences in the Gabor micro-patterns, clearly emerged. We conclude that texture transparency appears to result from an interaction between a boundary-detection mechanism defining the shape of each region and a surface-detection mechanism assigning the boundary.

  19. Facile fabrication of functional PDMS surfaces with tunable wettablity and high adhesive force via femtosecond laser textured templating

    Directory of Open Access Journals (Sweden)

    Yanlei Hu

    2014-12-01

    Full Text Available Femtosecond laser processing is emerged as a promising tool to functionalize surfaces of various materials, including metals, semiconductors, and polymers. However, the productivity of this technique is limited by the low efficiency of laser raster scanning. Here we report a facile approach for efficiently producing large-area functional polymer surfaces, by which metal is firstly textured by a femtosecond laser, and the as-prepared hierarchical structures are subsequently transferred onto polydimethylsiloxane (PDMS surfaces. Aluminum pieces covered by laser induced micro/nano-structures act as template masters and their performance of displaying diverse colors are investigated. Polymer replicas are endowed with tunable wetting properties, which are mainly attributed to the multi-scale surface structures. Furthermore, the surfaces are found to have extremely high adhesive force for water drops because of the high water penetration depth and the resultant high contact angle hysteresis. This characteristic facilitates many potential applications like loss-free tiny water droplets transportation. The reusability of metal master and easiness of soft lithography make it to be a very simple, fast and cost-efficient way for mass production of functional polymeric surfaces.

  20. Analysis of machinable structures and their wettability of rotary ultrasonic texturing method

    Science.gov (United States)

    Xu, Shaolin; Shimada, Keita; Mizutani, Masayoshi; Kuriyagawa, Tsunemoto

    2016-10-01

    Tailored surface textures at the micro- or nanoscale dimensions are widely used to get required functional performances. Rotary ultrasonic texturing (RUT) technique has been proved to be capable of fabricating periodic micro- and nanostructures. In the present study, diamond tools with geometrically defined cutting edges were designed for fabricating different types of tailored surface textures using the RUT method. Surface generation mechanisms and machinable structures of the RUT process are analyzed and simulated with a 3D-CAD program. Textured surfaces generated by using a triangular pyramid cutting tip are constructed. Different textural patterns from several micrometers to several tens of micrometers with few burrs were successfully fabricated, which proved that tools with a proper two-rake-face design are capable of removing cutting chips efficiently along a sinusoidal cutting locus in the RUT process. Technical applications of the textured surfaces are also discussed. Wetting properties of textured aluminum surfaces were evaluated by combining the test of surface roughness features. The results show that the real surface area of the textured aluminum surfaces almost doubled by comparing with that of a flat surface, and anisotropic wetting properties were obtained due to the obvious directional textural features.

  1. Surface-induced patterns from evaporating droplets of aqueous carbon nanotube dispersions

    KAUST Repository

    Zeng, Hongbo

    2011-06-07

    Evaporation of aqueous droplets of carbon nanotubes (CNTs) coated with a physisorbed layer of humic acid (HA) on a partially hydrophilic substrate induces the formation of a film of CNTs. Here, we investigate the role that the global geometry of the substrate surfaces has on the structure of the CNT film. On a flat mica or silica surface, the evaporation of a convex droplet of the CNT dispersion induces the well-known "coffee ring", while evaporation of a concave droplet (capillary meniscus) of the CNT dispersion in a wedge of two planar mica sheets or between two crossed-cylinder sheets induces a large area (>mm 2) of textured or patterned films characterized by different short- and long-range orientational and positional ordering of the CNTs. The resulting patterns appear to be determined by two competing or cooperative sedimentation mechanisms: (1) capillary forces between CNTs giving micrometer-sized filaments parallel to the boundary line of the evaporating droplet and (2) fingering instability at the boundary line of the evaporating droplet and subsequent pinning of CNTs on the surface giving micrometer-sized filaments of CNTs perpendicular to this boundary line. The interplay between substrate surface geometry and sedimentation mechanisms gives an extra control parameter for manipulating patterns of self-assembling nanoparticles at substrate surfaces. © 2011 American Chemical Society.

  2. The effects of sous-vide cooking parameters on texture and cell wall modifications in two apple cultivars: A response surface methodology approach.

    Science.gov (United States)

    Ortiz, Abel; Le Meurlay, Dominique; Lara, Isabel; Symoneaux, Ronan; Madieta, Emmanuel; Mehinagic, Emira

    2017-03-01

    This work aimed at evaluating the effects of sous-vide cooking parameters, such as time and temperature and their interactions, on textural attributes of 'Mondial Gala' and 'Granny Smith' apple cultivars. For this, different response surface methodology-based models were developed. This methodology proved a suitable means for the assessment of changes in textural parameters and cell wall modifications during the processing of apples. 'Mondial Gala' fruit displayed better aptitude for the preservation of textural properties after high-temperature processing conditions and were therefore apparently more suited to sous-vide cooking than 'Granny Smith' apples. Pectin methylesterase activity levels in 'Mondial Gala' apples were enhanced at mild temperatures and pectins in this cultivar displayed a lower degree of methylation. Therefore, the establishment of calcium-mediated linkages between cell wall polymers might have been favoured in 'Mondial Gala' apples, thus reinforcing tissues and improving the preservation of textural attributes, in comparison to 'Granny Smith' samples.

  3. The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs

    Science.gov (United States)

    Neiva, Rodrigo F.; Gil, Luiz Fernando; Tovar, Nick; Janal, Malvin N.; Marao, Heloisa Fonseca; Pinto, Nelson; Coelho, Paulo G.

    2016-01-01

    Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL) were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1) dual acid-etched (DAE, micrometer scale textured) and (2) micrometer/nanometer scale textured (Ossean™ surface). L-PRF (Intraspin system, Intra-Lock International) was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α = 0.05) evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal), individually or in combination on bone area fraction occupancy (BAFO). Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants. PMID:28042577

  4. Patterning surface by site selective capture of biopolymer hydrogel beads.

    Science.gov (United States)

    Guyomard-Lack, Aurélie; Moreau, Céline; Delorme, Nicolas; Marquis, Mélanie; Fang, Aiping; Bardeau, Jean-François; Cathala, Bernard

    2012-06-01

    This communication describes the fabrication of microstructured biopolymer surfaces by the site-selective capture of pectin hydrogel beads. A positively charged surface consisting of poly-L-lysine (PLL) was subjected to site-selective enzymatic degradation using patterned polydimethylsiloxane (PDMS) stamps covalently modified with trypsin, according to the recently described method. The patterned surface was used to capture ionically cross-linked pectin beads. The desired patterning of the hydrogel surfaces was generated by site-selective immobilization of these pectin beads. The ability of the hydrogels to be dried and swollen in water was assessed.

  5. Buffer layers on metal surfaces having biaxial texture as superconductor substrates

    Science.gov (United States)

    Paranthaman, Mariappan; Lee, Dominic F.; Kroeger, Donald M.; Goyal, Amit

    2000-01-01

    Buffer layer architectures are epitaxially deposited on biaxially-textured rolled substrates of nickel and/or copper and their alloys for high current conductors, and more particularly buffer layer architectures such as Y.sub.2 O.sub.3 /Ni, YSZ/Y.sub.2 O.sub.3 /Ni, RE.sub.2 O.sub.3 /Ni, (RE=Rare Earth), RE.sub.2 O.sub.3 /Y.sub.2 O.sub.3 /Ni, RE.sub.2 O.sub.3 /CeO.sub.2 /Ni, and RE.sub.2 O.sub.3 /YSZ/CeO.sub.2 /Ni, Y.sub.2 O.sub.3 /Cu, YSZ/Y.sub.2 O.sub.3 /Cu, RE.sub.2 O.sub.3 /Cu, RE.sub.2 O.sub.3 /Y.sub.2 O.sub.3 /Cu, RE.sub.2 O.sub.3 /CeO.sub.2 /Cu, and RE.sub.2 O.sub.3 /YSZ/CeO.sub.2 /Cu. Deposition methods include physical vapor deposition techniques which include electron-beam evaporation, rf magnetron sputtering, pulsed laser deposition, thermal evaporation, and solution precursor approaches, which include chemical vapor deposition, combustion CVD, metal-organic decomposition, sol-gel processing, and plasma spray.

  6. High fidelity replication of surface texture and geometric form of a high aspect ratio aerodynamic test component

    Science.gov (United States)

    Walton, Karl; Fleming, Leigh; Goodhand, Martin; Racasan, Radu; Zeng, Wenhan

    2016-06-01

    This paper details, assesses and validates a technique for the replication of a titanium wind tunnel test aerofoil in polyurethane resin. Existing resin replication techniques are adapted to overcome the technical difficulties associated with casting a high aspect ratio component. The technique is shown to have high replication fidelity over all important length-scales. The blade chord was accurate to 0.02%, and the maximum blade thickness was accurate to 2.5%. Important spatial and amplitude areal surface texture parameter were accurate to within 2%. Compared to an existing similar system using correlation areal parameters the current technique is shown to have lower fidelity and this difference is discussed. The current technique was developed for the measurement of boundary layer flow ‘laminar to turbulent’ transition for gas turbine compressor blade profiles and this application is illustrated.

  7. The impact of a Leidenfrost drop on a spoked surface texture

    Science.gov (United States)

    Shiri, Samira; Patterson, Colin; Bird, James

    2016-11-01

    Liquid drops can bounce when they impact non-wetting surfaces. Recently, studies have demonstrated that the time that the bouncing drop contacts a superhydrophobic surface can be reduced by incorporating ridged macrotextures on the surface. Yet the existing models aimed at explaining this phenomenon offer incompatible predictions of the contact time when a drop impacts multiple intersecting macrotextures, or spokes. Furthermore, it is unclear whether the effects of the macrotexture on the drop hydrodynamics extend to non-wetting surfaces in which direct contact is avoided by a thin vapor layer. Here we demonstrate that the phenomenon observed for macrotextured, superhydrophobic surfaces extends to macrotextured, wettable surfaces above the Leidenfrost temperature. We show that the number of droplets and overall residence time both depend on the number of intersecting spokes. Finally, we compare and contrast our results with mechanistic models to rationalize various elements of the phenomenon.

  8. A texture-based rolling bearing fault diagnosis scheme using adaptive optimal kernel time frequency representation and uniform local binary patterns

    Science.gov (United States)

    Chen, Haizhou; Wang, Jiaxu; Li, Junyang; Tang, Baoping

    2017-03-01

    This paper presents a new scheme for rolling bearing fault diagnosis using texture features extracted from the time-frequency representations (TFRs) of the signal. To derive the proposed texture features, firstly adaptive optimal kernel time frequency representation (AOK-TFR) is applied to extract TFRs of the signal which essentially describe the energy distribution characteristics of the signal over time and frequency domain. Since the AOK-TFR uses the signal-dependent radially Gaussian kernel that adapts over time, it can exactly track the minor variations in the signal and provide an excellent time-frequency concentration in noisy environment. Simulation experiments are furthermore performed in comparison with common time-frequency analysis methods under different noisy conditions. Secondly, the uniform local binary pattern (uLBP), which is a computationally simple and noise-resistant texture analysis method, is used to calculate the histograms from the TFRs to characterize rolling bearing fault information. Finally, the obtained histogram feature vectors are input into the multi-SVM classifier for pattern recognition. We validate the effectiveness of the proposed scheme by several experiments, and comparative results demonstrate that the new fault diagnosis technique performs better than most state-of-the-art techniques, and yet we find that the proposed algorithm possess the adaptivity and noise resistance qualities that could be very useful in real industrial applications.

  9. Non-textured laser modification of silica glass surface: Wettability control and flow channel formation

    Science.gov (United States)

    Aono, Yuko; Hirata, Atsushi; Tokura, Hitoshi

    2016-05-01

    Local wettability of silica glass surface is modified by infrared laser irradiation. The silica glass surface exhibits hydrophobic property in the presence of sbnd CF3 or sbnd (CH3)2 terminal functional groups, which are decomposed by thermal treatment, and degree of the decomposition depends on the applied heat. Laser irradiation can control the number of remaining functional groups according to the irradiation conditions; the contact angle of deionized water on the laser modified surfaces range from 100° to 40°. XPS analysis confirms that the variation in wettability corresponds to the number of remaining sbnd CF3 groups. The laser irradiation achieves surface modification without causing any cracks or damages to the surface, as observed by SEM and AFM; moreover, surface transparency to visible light and surface roughness remains unaffected. The proposed method is applied to plane flow channel systems. Dropped water spreads only on the hydrophilic and invisible line modified by the laser irradiation without formation of any grooves. This indicates that the modified line can act as a surface channel. Furthermore, self-transportation of liquid is also demonstrated on a channel with gradually-varied wettability along its length. A water droplet on a hydrophobic side is self-transported to a hydrophilic side due to contact-angle hysteresis force without any actuators or external forces.

  10. Wetting property of smooth and textured hydrophobic surfaces under condensation condition

    Science.gov (United States)

    Hao, PengFei; Lv, CunJing; Yao, ZhaoHui; Niu, FengLei

    2014-11-01

    Static and dynamic wetting behaviors of sessile droplet on smooth, microstructured and micro/nanostructured surface under condensation condition are systematically studied. In contrast to the conventional droplet wetting on such natural materials by dropping, we demonstrate here that when dropwise condensation occurs, the sessile droplet will transit from the Cassie-Baxter wetting state to the Wenzel wetting state or partial Cassie-Baxter wetting state on the microstructured surface or the micro/nanostructured surface, which leads to a strong adhesion between the droplet and the substrate. In contrast, the apparent contact angle and the sliding angle on the smooth surface changes a little before and after the condensation because of small roughness. Theoretical analysis shows that the roughness factor controls the adhesion force of the droplet during condensation, and a theoretical model is constructed which will be helpful for us to understand the relationship between the adhesion force and the geometry of the surface.

  11. Physically and chemically stable ionic liquid-infused textured surfaces showing excellent dynamic omniphobicity

    Directory of Open Access Journals (Sweden)

    Daniel F. Miranda

    2014-05-01

    Full Text Available A fluorinated and hydrophobic ionic liquid (IL, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide, effectively served as an advantageous lubricating liquid for the preparation of physically and chemically stable omniphobic surfaces based on slippery liquid-infused porous surfaces. Here, we used particulate microstructures as supports, prepared by the chemical vapor deposition of 1,3,5,7-tetramethylcyclotetrasiloxane and subsequent surface modification with (3-aminopropyltriethoxysilane. Confirmed by SEM and contact angle measurements, the resulting IL-infused microtextured surfaces are smooth and not only water but also various low surface tension liquids can easily slide off at low substrate tilt angles of <5°, even after exposure to high temperature, vacuum, and UV irradiation.

  12. Physically and chemically stable ionic liquid-infused textured surfaces showing excellent dynamic omniphobicity

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Daniel F.; Urata, Chihiro; Masheder, Benjamin; Dunderdale, Gary J.; Hozumi, Atsushi, E-mail: a.hozumi@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98, Anagahora, Shimo-Shidami, Moriyama-ku, Nagoya, Aichi 463-8560 (Japan); Yagihashi, Makoto [Nagoya Municipal Industrial Research Institute, Rokuban, Atsuta-ku, Nagoya 456-0058 (Japan)

    2014-05-01

    A fluorinated and hydrophobic ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, effectively served as an advantageous lubricating liquid for the preparation of physically and chemically stable omniphobic surfaces based on slippery liquid-infused porous surfaces. Here, we used particulate microstructures as supports, prepared by the chemical vapor deposition of 1,3,5,7-tetramethylcyclotetrasiloxane and subsequent surface modification with (3-aminopropyl)triethoxysilane. Confirmed by SEM and contact angle measurements, the resulting IL-infused microtextured surfaces are smooth and not only water but also various low surface tension liquids can easily slide off at low substrate tilt angles of <5°, even after exposure to high temperature, vacuum, and UV irradiation.

  13. Role of roughness parameters on the tribology of randomly nano-textured silicon surface.

    Science.gov (United States)

    Gualtieri, E; Pugno, N; Rota, A; Spagni, A; Lepore, E; Valeri, S

    2011-10-01

    This experimental work is oriented to give a contribution to the knowledge of the relationship among surface roughness parameters and tribological properties of lubricated surfaces; it is well known that these surface properties are strictly related, but a complete comprehension of such correlations is still far to be reached. For this purpose, a mechanical polishing procedure was optimized in order to induce different, but well controlled, morphologies on Si(100) surfaces. The use of different abrasive papers and slurries enabled the formation of a wide spectrum of topographical irregularities (from the submicro- to the nano-scale) and a broad range of surface profiles. An AFM-based morphological and topographical campaign was carried out to characterize each silicon rough surface through a set of parameters. Samples were subsequently water lubricated and tribologically characterized through ball-on-disk tribometer measurements. Indeed, the wettability of each surface was investigated by measuring the water droplet contact angle, that revealed a hydrophilic character for all the surfaces, even if no clear correlation with roughness emerged. Nevertheless, this observation brings input to the purpose, as it allows to exclude that the differences in surface profile affect lubrication. So it is possible to link the dynamic friction coefficient of rough Si samples exclusively to the opportune set of surface roughness parameters that can exhaustively describe both height amplitude variations (Ra, Rdq) and profile periodicity (Rsk, Rku, Ic) that influence asperity-asperity interactions and hydrodynamic lift in different ways. For this main reason they cannot be treated separately, but with dependent approach through which it was possible to explain even counter intuitive results: the unexpected decreasing of friction coefficient with increasing Ra is justifiable by a more consistent increasing of kurtosis Rku.

  14. An ontology design pattern for surface water features

    Science.gov (United States)

    Sinha, Gaurav; Mark, David; Kolas, Dave; Varanka, Dalia; Romero, Boleslo E.; Feng, Chen-Chieh; Usery, E. Lynn; Liebermann, Joshua; Sorokine, Alexandre

    2014-01-01

    Surface water is a primary concept of human experience but concepts are captured in cultures and languages in many different ways. Still, many commonalities exist due to the physical basis of many of the properties and categories. An abstract ontology of surface water features based only on those physical properties of landscape features has the best potential for serving as a foundational domain ontology for other more context-dependent ontologies. The Surface Water ontology design pattern was developed both for domain knowledge distillation and to serve as a conceptual building-block for more complex or specialized surface water ontologies. A fundamental distinction is made in this ontology between landscape features that act as containers (e.g., stream channels, basins) and the bodies of water (e.g., rivers, lakes) that occupy those containers. Concave (container) landforms semantics are specified in a Dry module and the semantics of contained bodies of water in a Wet module. The pattern is implemented in OWL, but Description Logic axioms and a detailed explanation is provided in this paper. The OWL ontology will be an important contribution to Semantic Web vocabulary for annotating surface water feature datasets. Also provided is a discussion of why there is a need to complement the pattern with other ontologies, especially the previously developed Surface Network pattern. Finally, the practical value of the pattern in semantic querying of surface water datasets is illustrated through an annotated geospatial dataset and sample queries using the classes of the Surface Water pattern.

  15. Effect of energy drinks on the surface texture of nanoflled composite resin.

    Science.gov (United States)

    Al-Samadani, Khalid H

    2013-09-01

    To study the effect of three energy drinks on the surface roughness of nanoflled composite resins after different periods of aging time. Composite resin disks, 6 mm diameter, 3 mm thickness were prepared from Filtec Z350 XT, Tetric EvoCeram and Filtec Z250 XT. Specimens fr/8om each material were tested after aging with Red Bull, Bison and Power Horse energy drinks and distilled water as a control. Specimens were stored at 37°C in dark containers for 1, 3 and 6 months. Surface roughness Ra was assessed using a surface scanning interferometry before and after each storage period. Surface roughness differences ΔRa and Ra among specimens were measured. Mean values were statistically analyzed using multiple repeated measured (ANOVA), variance and multiple comparisons of the mean values were done with Bonferroni test, with p energy drinks was signifcantly different for all tested materials at all three times p Energy drinks used in this study had surface degradation effect on the tested composite resin materials. The surface roughness increased with aging time however, it was clinically acceptable in all test groups after 6 months. The effect of energy drinks solutions on the surface roughness parameter of resin composites depends on type of solution and its acidity contents.

  16. Generation of 1D interference patterns of Bloch surface waves

    Science.gov (United States)

    Kadomina, E. A.; Bezus, E. A.; Doskolovich, L. L.

    2016-09-01

    Interference patterns of Bloch surface waves with a period that is significantly less than the wavelength of incident radiation are formed using dielectric diffraction gratings located on the surface of photonic crystal. The simulation based on electromagnetic diffraction theory is used to demonstrate the possibility of high-quality interference patterns due to resonant enhancement of higher evanescent diffraction orders related to the excitation of the Bloch surface waves. The contrast of the interference patterns is close to unity, and the period is less than the period of the diffraction structure by an order of magnitude.

  17. Anti-adhesion effects of liquid-infused textured surfaces on high-temperature stainless steel for soft tissue

    Science.gov (United States)

    Zhang, Pengfei; Chen, Huawei; Zhang, Liwen; Zhang, Deyuan

    2016-11-01

    Soft tissue adhesion on the electrosurgical instruments can induce many serious complications, such as failure of hemostasis and damage to the surrounding soft tissue. The soft tissue adhesion is mainly caused by the high temperature on the instrument surface generally made of stainless steel. Nepenthes inspired liquid-infused surfaces (LIS), highly promising for anti-adhesion, have attracted considerable interests. In this paper, we investigated the anti-adhesion effects of LIS on high-temperature stainless steel for soft tissue for the first time, aiming to develop a new approach to solve the soft tissue adhesion problem. The textured surface, acting as the holding structures, was fabricated by photolithography-assisted chemical etching. Silicone oil, with good biocompatibility and high-temperature resistance, was chosen as the infused liquid. The adhesion force measurements for soft tissue on the LIS at high temperatures indicated that the soft tissue adhesion force was decreased by approximately 80% at 250 °C. Besides, the cycle tests of soft tissue adhesion force demonstrated the excellent stability of prepared LIS. We anticipate that LIS will be of great promise for practical applications on the electrosurgical instruments.

  18. Atomically flat surface of (0 0 1) textured FePt thin films by residual stress control

    Science.gov (United States)

    Liu, S. H.; Hsiao, S. N.; Chou, C. L.; Chen, S. K.; Lee, H. Y.

    2015-11-01

    Single-layered Fe52Pt48 films with thickness of 10 nm were sputter-deposited on glass substrates. Rapid thermal annealing with different heating rates (10-110 K/s) was applied to transform as-deposited fcc phase into L10 phase and meanwhile to align [0 0 1]-axis of L10 crystal along plane normal direction. Based on X-ray diffractometry using synchrotron radiation source, the texture coefficient of (0 0 1)-plane increases with increasing heating rate from 10 to 40 K/s, which is correlated with perpendicular magnetic anisotropy and in-plane tensile stress analyzed by asymmetric sin2 ψ method. Furthermore, it was revealed by atomic force microscopy that the dewetting process occurred as heating rate was raised up to 80 K/s and higher. The change in the microstructure due to stress relaxation leads to the degradation of (0 0 1) orientation and magnetic properties. Surface roughness is closely related to the in-plane tensile stress. Enhanced perpendicular magnetic anisotropy and atomically flat surface were achieved for the samples annealed at 40 K/s, which may be suitable for further practical applications. This work also suggests a feasible way for surface engineering by controlling internal stress of the FePt without introducing cap layer.

  19. Experimental study of surface texture and resonance mechanism of booming sand

    Institute of Scientific and Technical Information of China (English)

    QU; JianJun; ZHANG; KeCun; SUN; Bo; JIANG; ShengXiang; DONG; GuangRong; ZU; RuiPing; FANG; HaiYan

    2007-01-01

    The sound-producing mechanism of booming sand has long been a pending problem in the blown sand physics. Based on the earlier researches, the authors collected some silent sand samples from Tengger Desert, Australian Desert, Kuwait Desert, beaches of Hainan Island and Japanese coast as well as the soundless booming sand samples from the Mingsha Mountain in Dunhuang to make washing experiments. In the meantime the chemical corrosion experiment of glass micro-spheres, surface coating experiment and SEM examination were also conducted. The experimental results show that the sound production of booming sand seems to have nothing to do with the presence of SiO2 gel on the surface of sand grains and unrelated to the surface chemical composition of sand grains but is related to the resonance cavities formed by porous (pit-like) physical structure resulting from a number of factors such as wind erosion, water erosion, chemical corrosion and SiO2 gel deposition, etc. Its resonance mechanism is similar to that of Hemholz resonance cavity. Under the action of external forces, numerous spherical and sand grains with smooth surface and porous surface are set in motion and rub with each other to produce extremely weak vibration sound and then become audible sound by human ears through the magnification of surface cavity resonance. However the booming sands may lose their resonance mechanism and become silent sand due to the damping action caused by the invasion of finer particles such as dust and clay into surface holes of sand grains. Therefore, clearing away fine pollutants on the quartz grain surface is an effective way to make silent sand emit audible sound.

  20. 表面结构的分类与识别%Classification and Recognition of Surface Texture

    Institute of Scientific and Technical Information of China (English)

    MURALIKRISHNAN B; BUI Son H; RAJA J

    2004-01-01

    Measurement and characterization of surface texture is an important aspect of precision metrology.Historically this has involved partitioning a profile into different wavelength regimes referred to as roughness,waviness and form followed by numerical quantization.Parameters computed are then inspected for tolerance compliance to ensure a part performs its intended function.This approach is satisfactory when the specification has been carefully determined and the process is sta ble.However,when the manufacturing process is under development or when instability or modifications to the process in validate specifications,there is a need to study surface finish parameters in relation to functional performance or process measures.In this context,the problem of surface texture classification and recognition are discussed.Advanced techniques developed for this purpose along with applications are presented.Also,the techniques discussed here will be useful across large bandwidth,from the characterization of nano scale to traditional micro scale surfaces.%表面结构的测量与特征描述是精密计量技术的一个重要方面,传统上包括将轮廓情况根据不同的波长范围划分为粗糙度、波纹度和形状及后续的数字量化.按算得的参数检查它是否为公差允许,以保证零件执行其指定的功能.当技术特性已经经过仔细确定,并且其过程稳定时,该方法是令人满意的;但是,当制造过程正在进行中或过程的不稳定、过程变化使技术特性失效时,就需要研究和功能表现及过程评定相关的表面参数.讨论了表面结构的分类与识别问题.同时阐述了为此目的而开发的先进技术及其应用.所研究的技术对从纳米尺度到传统的微米尺度的较大带宽范围内的表面特征描述都是有效的.

  1. Parametrization of textural patterns in {sup 123}I-ioflupane imaging for the automatic detection of Parkinsonism

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Murcia, F. J., E-mail: fjesusmartinez@ugr.es; Górriz, J. M.; Ramírez, J. [Signal Processing and Biomedical Applications Research Group, Department of Signal Theory, Networking and Communications, University of Granada, Granada 18071 (Spain); Moreno-Caballero, M.; Gómez-Río, M. [Department of Nuclear Medicine, Virgen de las Nieves Hospital, Granada 18071 (Spain)

    2014-01-15

    Purpose: A novel approach to a computer aided diagnosis system for the Parkinson's disease is proposed. This tool is intended as a supporting tool for physicians, based on fully automated methods that lead to the classification of{sup 123}I-ioflupane SPECT images. Methods: {sup 123}I-ioflupane images from three different databases are used to train the system. The images are intensity and spatially normalized, then subimages are extracted and a 3D gray-level co-occurrence matrix is computed over these subimages, allowing the characterization of the texture using Haralick texture features. Finally, different discrimination estimation methods are used to select a feature vector that can be used to train and test the classifier. Results: Using the leave-one-out cross-validation technique over these three databases, the system achieves results up to a 97.4% of accuracy, and 99.1% of sensitivity, with positive likelihood ratios over 27. Conclusions: The system presents a robust feature extraction method that helps physicians in the diagnosis task by providing objective, operator-independent textural information about{sup 123}I-ioflupane images, commonly used in the diagnosis of the Parkinson's disease. Textural features computation has been optimized by using a subimage selection algorithm, and the discrimination estimation methods used here makes the system feature-independent, allowing us to extend it to other databases and diseases.

  2. When lithography meets self-assembly: a review of recent advances in the directed assembly of complex metal nanostructures on planar and textured surfaces

    Science.gov (United States)

    Hughes, Robert A.; Menumerov, Eredzhep; Neretina, Svetlana

    2017-07-01

    One of the foremost challenges in nanofabrication is the establishment of a processing science that integrates wafer-based materials, techniques, and devices with the extraordinary physicochemical properties accessible when materials are reduced to nanoscale dimensions. Such a merger would allow for exacting controls on nanostructure positioning, promote cooperative phenomenon between adjacent nanostructures and/or substrate materials, and allow for electrical contact to individual or groups of nanostructures. With neither self-assembly nor top-down lithographic processes being able to adequately meet this challenge, advancements have often relied on a hybrid strategy that utilizes lithographically-defined features to direct the assembly of nanostructures into organized patterns. While these so-called directed assembly techniques have proven viable, much of this effort has focused on the assembly of periodic arrays of spherical or near-spherical nanostructures comprised of a single element. Work directed toward the fabrication of more complex nanostructures, while still at a nascent stage, has nevertheless demonstrated the possibility of forming arrays of nanocubes, nanorods, nanoprisms, nanoshells, nanocages, nanoframes, core-shell structures, Janus structures, and various alloys on the substrate surface. In this topical review, we describe the progress made in the directed assembly of periodic arrays of these complex metal nanostructures on planar and textured substrates. The review is divided into three broad strategies reliant on: (i) the deterministic positioning of colloidal structures, (ii) the reorganization of deposited metal films at elevated temperatures, and (iii) liquid-phase chemistry practiced directly on the substrate surface. These strategies collectively utilize a broad range of techniques including capillary assembly, microcontact printing, chemical surface modulation, templated dewetting, nanoimprint lithography, and dip-pen nanolithography and

  3. On Discrete Killing Vector Fields and Patterns on Surfaces

    KAUST Repository

    Ben-Chen, Mirela

    2010-09-21

    Symmetry is one of the most important properties of a shape, unifying form and function. It encodes semantic information on one hand, and affects the shape\\'s aesthetic value on the other. Symmetry comes in many flavors, amongst the most interesting being intrinsic symmetry, which is defined only in terms of the intrinsic geometry of the shape. Continuous intrinsic symmetries can be represented using infinitesimal rigid transformations, which are given as tangent vector fields on the surface - known as Killing Vector Fields. As exact symmetries are quite rare, especially when considering noisy sampled surfaces, we propose a method for relaxing the exact symmetry constraint to allow for approximate symmetries and approximate Killing Vector Fields, and show how to discretize these concepts for generating such vector fields on a triangulated mesh. We discuss the properties of approximate Killing Vector Fields, and propose an application to utilize them for texture and geometry synthesis. Journal compilation © 2010 The Eurographics Association and Blackwell Publishing Ltd.

  4. Wetting property of smooth and textured hydrophobic surfaces under condensation condition

    Institute of Scientific and Technical Information of China (English)

    HAO PengFei; LV CunJing; YAO ZhaoHui; NIU FengLei

    2014-01-01

    Static and dynamic wetting behaviors of sessile droplet on smooth,microstructured and micro/nanostructured surface under condensation condition are systematically studied.In contrast to the conventional droplet wetting on such natural materials by dropping,we demonstrate here that when dropwise condensation occurs,the sessile droplet will transit from the Cassie-Baxter wetting state to the Wenzel wetting state or partial Cassie-Baxter wetting state on the microstructured surface or the micro/nanostructured surface,which leads to a strong adhesion between the droplet and the substrate.In contrast,the apparent contact angle and the sliding angle on the smooth surface changes a little before and after the condensation because of small roughness.Theoretical analysis shows that the roughness factor controls the adhesion force of the droplet during condensation,and a theoretical model is constructed which will be helpful for us to understand the relationship between the adhesion force and the geometry of the surface.

  5. Biomolecule surface patterning may enhance membrane association

    CERN Document Server

    Pogodin, Sergey; Baulin, Vladimir A

    2012-01-01

    Under dehydration conditions, amphipathic Late Embryogenesis Abundant (LEA) proteins fold spontaneously from a random conformation into alpha-helical structures and this transition is promoted by the presence of membranes. To gain insight into the thermodynamics of membrane association we model the resulting alpha-helical structures as infinite rigid cylinders patterned with hydrophobic and hydrophilic stripes oriented parallel to their axis. Statistical thermodynamic calculations using Single Chain Mean Field (SCMF) theory show that the relative thickness of the stripes controls the free energy of interaction of the alpha-helices with a phospholipid bilayer, as does the bilayer structure and the depth of the equilibrium penetration of the cylinders into the bilayer. The results may suggest the optimal thickness of the stripes to mimic the association of such protein with membranes.

  6. Surface roughness measurement using dichromatic speckle pattern: an experimental study.

    Science.gov (United States)

    Fujii, H; Lit, J W

    1978-09-01

    Surface roughness is studied experimentally by making use of the statistical properties of dichromatic speckle patterns. The rms intensity difference between two speckle patterns produced by two argon laser lines are analyzed in the far field as functions of the object surface roughness and the difference in the two wavenumbers of the illuminating light. By applying previously derived formulas, the rms surface roughness is obtained from rms intensity differences. Glass and metal rough surfaces are used. Other than the scattering arrangement, the experimental setup has a simple spectrometric system and an electronic analyzing circuit.

  7. SHAPE FROM TEXTURE USING LOCALLY SCALED POINT PROCESSES

    Directory of Open Access Journals (Sweden)

    Eva-Maria Didden

    2015-09-01

    Full Text Available Shape from texture refers to the extraction of 3D information from 2D images with irregular texture. This paper introduces a statistical framework to learn shape from texture where convex texture elements in a 2D image are represented through a point process. In a first step, the 2D image is preprocessed to generate a probability map corresponding to an estimate of the unnormalized intensity of the latent point process underlying the texture elements. The latent point process is subsequently inferred from the probability map in a non-parametric, model free manner. Finally, the 3D information is extracted from the point pattern by applying a locally scaled point process model where the local scaling function represents the deformation caused by the projection of a 3D surface onto a 2D image.

  8. A 2-year report on maxillary and mandibular fixed partial dentures supported by Astra Tech dental implants. A comparison of 2 implants with different surface textures

    DEFF Research Database (Denmark)

    Karlsson, U; Gotfredsen, K; Olsson, C

    1998-01-01

    In 50 partially edentulous patients, 133 (48 maxillary; 85 mandibular) Astra Tech dental implants of 2 different surface textures (machined; TiO-blasted) were alternately installed, supporting 52 fixed partial dentures (FPDs). Before abutment connection 2 machined implants (1 mandibular; 1...

  9. Assessment methods of injection moulded nano-patterned surfaces

    DEFF Research Database (Denmark)

    Menotti, S.; Bisacco, G.; Hansen, H. N.

    2014-01-01

    algorithm for feature recognition. To compare the methods, the mould insert and a number of replicated nano-patterned surfaces, injection moulded with an induction heating aid, were measured on nominally identical locations by means of an atomic force microscope mounted on a manual CMM........ In this work two different methods for quantitative characterization of random nano-patterned surfaces were compared and assessed. One method is based on the estimation of the roughness amplitude parameters Sa and Sz (ISO 25178). The second method is based on pore and particle analysis using the watershed......Assessment of nano-patterned surfaces requires measurements with nano-metric resolution. In order to enable the optimization of the moulding process it is necessary to develop a robust method for quantitative characterization of the replication quality of random nano-patterned surfaces...

  10. Mechanical properties and fractal analysis of the surface texture of sputtered hydroxyapatite coatings

    Science.gov (United States)

    Bramowicz, Miroslaw; Braic, Laurentiu; Azem, Funda Ak; Kulesza, Slawomir; Birlik, Isil; Vladescu, Alina

    2016-08-01

    This aim of this work is to establish a relationship between the surface morphology and mechanical properties of hydroxyapatite coatings prepared using RF magnetron sputtering at temperatures in the range from 400 to 800 °C. The topography of the samples was scanned using atomic force microscopy, and the obtained 3D maps were analyzed using fractal methods to derive the spatial characteristics of the surfaces. X-ray photoelectron spectroscopy revealed the strong influence of the deposition temperature on the Ca/P ratio in the growing films. The coatings deposited at 600-800 °C exhibited a Ca/P ratio between 1.63 and 1.69, close to the stoichiometric hydroxyapatite (Ca/P = 1.67), which is crucial for proper osseointegration. Fourier-transform infrared spectroscopy showed that the intensity of phosphate absorption bands increased with increasing substrate temperature. Each sample exhibited well defined and sharp hydroxyapatite band at 566 cm-1, although more pronounced for the coatings deposited above 500 °C. Both the hardness and elastic modulus of the coated samples decrease with increasing deposition temperature. The surface morphology strongly depends on the deposition temperature. The sample deposited at 400 °C exhibits circular cavities dug in an otherwise flat surface. At higher deposition temperatures, these cavities increase in size and start to overlap each other so that at 500 °C the surface is composed of closely packed peaks and ridges. At that point, the characteristics of the surface turns from the dominance of cavities to grains of similar size, and develops in a similar manner at higher temperatures.

  11. Nickel replicas as calibration reference standards for industrial surface texture instruments

    DEFF Research Database (Denmark)

    Sammatini-Malberg, Maria-Pia

    The present report is a documentation of measurements carried out at DTU on Nickel replicas. The research is performed in the frame of the project with contract SMT4-CT97-2176 with title: Calibration Standards for Surface Topography Measuring Systems down to Nanometric Scale.......The present report is a documentation of measurements carried out at DTU on Nickel replicas. The research is performed in the frame of the project with contract SMT4-CT97-2176 with title: Calibration Standards for Surface Topography Measuring Systems down to Nanometric Scale....

  12. Effect of superhydrophobic surface morphology on evaporative deposition patterns

    Science.gov (United States)

    Dicuangco, Mercy; Dash, Susmita; Weibel, Justin A.; Garimella, Suresh V.

    2014-05-01

    Prediction and active control of the spatial distribution of particulate deposits obtained from sessile droplet evaporation are vital in printing, nanostructure assembly, biotechnology, and other applications that require localized deposits. This Letter presents surface wettability-based localization of evaporation-driven particulate deposition and the effect of superhydrophobic surface morphology on the distribution of deposits. Sessile water droplets containing suspended latex particles are evaporated on non-wetting textured surfaces with varying microstructure geometry at ambient conditions. The droplets are visualized throughout the evaporation process to track the temporal evolution of contact radius and apparent contact angle. The resulting particle deposits on the substrates are quantitatively characterized. The experimental results show that superhydrophobic surfaces suppress contact-line deposition during droplet evaporation, thereby providing an effective means of localizing the deposition of suspended particles. A correlation between deposit size and surface morphology, explained in terms of the interface pressure balance at the transition between wetting states, reveals an optimum surface morphology for minimizing the deposit coverage area.

  13. Photochromic film texturing with speckle illumination: application to goods authentication

    Science.gov (United States)

    Crespo-Monteiro, Nicolas; Destouches, Nathalie; Fournel, Thierry

    2012-10-01

    Thanks to the localized surface plasmon resonance of silver nanoparticles, mesoporous titania films loaded with silver salts manifest a photochromic behavior that can be used to perform updatable laser microinscriptions. Under UV illumination, the silver salts are reduced into silver nanoparticles and the illuminated areas become grey-brown. This coloration can be completely erased by oxidizing the silver nanoparticles with a polychromatic or monochromatic visible light whose spectrum lies in the resonance band of silver nanoparticles. The paper investigates the usage of such photochromic Ag/TiO2 films for creating an updatable random texturing. Random textures are produced on coated glass samples, initially homogeneous, by exposing them to speckle patterns resulting from the scattering of a UV laser beam from an optically rough surface. The stability of such textures under homogeneous UV post-exposures is investigated as a function of the speckle exposure time. Under optimized exposure conditions, the textures remain stable enough for a long time and the differences between textures are sufficiently discriminative to use the texturing process for goods authentication. This is demonstrated by calculating the correlation coefficient of thousands of couples of texture images. The numerical treatment of images has the advantage to be robust to changes in the sample repositioning between different image records. The rewritability of the samples is characterized through the comparison of different textures successively erased and written at the same place on multiple samples.

  14. Phakic Pattern Pseudoexfoliation Material Accumulation on Intraocular Lens Surface

    Directory of Open Access Journals (Sweden)

    Emre Güler

    2014-03-01

    Full Text Available Pseudophakic pseudoexfoliation is the accumulation of pseudoexfoliation material on the intraocular lens. Most of the cases have showed scattered flecks of pseudoexfoliation material on the surface of the intraocular lens. However, the phakic pattern consisting of classic three-zone on the intraocular lens is rarely observed. In this case report, we describe a phakic pattern pseudoexfoliation material on the intraocular lens surface 8 years after cataract extraction. (Turk J Ophthalmol 2014; 44: 156-7

  15. Phakic Pattern Pseudoexfoliation Material Accumulation on Intraocular Lens Surface

    OpenAIRE

    Emre Güler; Aylin Tenlik; Tuba Kara Akyüz

    2014-01-01

    Pseudophakic pseudoexfoliation is the accumulation of pseudoexfoliation material on the intraocular lens. Most of the cases have showed scattered flecks of pseudoexfoliation material on the surface of the intraocular lens. However, the phakic pattern consisting of classic three-zone on the intraocular lens is rarely observed. In this case report, we describe a phakic pattern pseudoexfoliation material on the intraocular lens surface 8 years after cataract extraction. (Turk J Ophthalm...

  16. Nickel replicas as calibration reference standards for industrial surface texture instruments

    DEFF Research Database (Denmark)

    Sammatini-Malberg, Maria-Pia

    The present report is a documentation of measurements carried out at DTU on Nickel replicas. The research is performed in the frame of the project with contract SMT4-CT97-2176 with title: Calibration Standards for Surface Topography Measuring Systems down to Nanometric Scale....

  17. Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

    2012-07-01

    Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

  18. SUPPLEMENTARY COMPARISON - EUROMET.L-S11 comparison on surface texture

    DEFF Research Database (Denmark)

    Koenders, L.; Andreasen, Jan Lasson; De Chiffre, Leonardo

    2004-01-01

    The measurement of roughness of technical surfaces is important in research and for industry. There are a lot of 2D roughness parameters that are defined and standardized by ISO. Calibration standards can be used to calibrate the instruments and ensure traceability to the SI unit of length. Most ...

  19. Mechanical properties and fractal analysis of the surface texture of sputtered hydroxyapatite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Bramowicz, Miroslaw [University of Warmia and Mazury in Olsztyn, Faculty of Technical Sciences, Oczapowskiego 11, 10-719 Olsztyn (Poland); Braic, Laurentiu [National Institute for Optoelectronics, 409 Atomistilor, 077125, Magurele (Romania); Azem, Funda Ak [Dokuz Eylul University, Engineering Faculty, Metallurgical and Materials Engineering Department, Tinaztepe Campus, 35397, Izmir (Turkey); Kulesza, Slawomir [University of Warmia and Mazury in Olsztyn, Faculty of Mathematics and Computer Science, Sloneczna 54, 10-710 Olsztyn (Poland); Birlik, Isil [Dokuz Eylul University, Engineering Faculty, Metallurgical and Materials Engineering Department, Tinaztepe Campus, 35397, Izmir (Turkey); Vladescu, Alina, E-mail: alinava@inoe.ro [National Institute for Optoelectronics, 409 Atomistilor, 077125, Magurele (Romania)

    2016-08-30

    Highlights: • Hydroxyapatite were prepared at temperatures in the range from 400 to 800 °C. • The coatings prepared at 800 °C is closer to the stoichiometric hydroxyapatite. • Hardness and elastic modulus decreased with increasing deposition temperature. • The surface morphology strongly depends on the deposition temperature. • Mesokurtic height distribution pulled towards larger heights were formed at high temperature. - Abstract: This aim of this work is to establish a relationship between the surface morphology and mechanical properties of hydroxyapatite coatings prepared using RF magnetron sputtering at temperatures in the range from 400 to 800 °C. The topography of the samples was scanned using atomic force microscopy, and the obtained 3D maps were analyzed using fractal methods to derive the spatial characteristics of the surfaces. X-ray photoelectron spectroscopy revealed the strong influence of the deposition temperature on the Ca/P ratio in the growing films. The coatings deposited at 600–800 °C exhibited a Ca/P ratio between 1.63 and 1.69, close to the stoichiometric hydroxyapatite (Ca/P = 1.67), which is crucial for proper osseointegration. Fourier-transform infrared spectroscopy showed that the intensity of phosphate absorption bands increased with increasing substrate temperature. Each sample exhibited well defined and sharp hydroxyapatite band at 566 cm{sup −1}, although more pronounced for the coatings deposited above 500 °C. Both the hardness and elastic modulus of the coated samples decrease with increasing deposition temperature. The surface morphology strongly depends on the deposition temperature. The sample deposited at 400 °C exhibits circular cavities dug in an otherwise flat surface. At higher deposition temperatures, these cavities increase in size and start to overlap each other so that at 500 °C the surface is composed of closely packed peaks and ridges. At that point, the characteristics of the surface turns from the

  20. Identification and comparison of electrical tapes using instrumental and statistical techniques: I. Microscopic surface texture and elemental composition.

    Science.gov (United States)

    Goodpaster, John V; Sturdevant, Amanda B; Andrews, Kristen L; Brun-Conti, Leanora

    2007-05-01

    Comparisons of polyvinyl chloride electrical tape typically rely upon evaluating class characteristics such as physical dimensions, surface texture, and chemical composition. Given the various techniques that are available for this purpose, a comprehensive study has been undertaken to establish an optimal analytical scheme for electrical tape comparisons. Of equal importance is the development of a quantitative means for sample discrimination. In this study, 67 rolls of black electrical tape representing 34 different nominal brands were analyzed via scanning electron microscopy and energy dispersive spectroscopy. Differences in surface roughness, calendering marks, and filler particle size were readily apparent, including between some rolls of the same nominal brand. The relative amounts of magnesium, aluminum, silicon, sulfur, lead, chlorine, antimony, calcium, titanium, and zinc varied greatly between brands and, in some cases, could be linked to the year of manufacture. For the first time, quantitative differentiation of electrical tapes was achieved through multivariate statistical techniques, with 36 classes identified within the sample population. A single-blind study was also completed where questioned tape samples were correctly associated with known exemplars. Finally, two case studies are presented where tape recovered from an improvised explosive device is compared with tape recovered from a suspect.

  1. Modification of Activated Carbon by Means of Microwave Heating and Its Effects on the Pore Texture and Surface Chemistry

    Directory of Open Access Journals (Sweden)

    Liqiang Zhang

    2013-02-01

    Full Text Available Two kinds of typical activated carbons (coal based AC and coconut shell based AC were modified in a flow of N2 gas has been carried out using a microwave device operating at 2450 MHz and different input power, instead of a conventional furnace. The samples were analyzed by means of low temperature N2 adsorption, elemental analysis and Boehm titration. The results show that microwave heating is an effective means of activated carbon modification. The temperature of activated carbon increases rapidly under microwave heating and then gradual increase to a quasi-stationary temperature. The pore texture of activated carbon changes slightly after microwave treatment and the two activated carbons still keep rich pore structure. The oxygen functional groups decompose and evolve with the form of CO and CO2. This in turn gives rise to a significant decrease in oxygen content. These changes of oxygen contents increase as the microwave input power increases. During microwave treatment, a gradual decrease in the surface acidic functional groups is observed. More important, with the removal of the surface acidic groups, the number of the basic group increased gradually, the activated carbon with oxygen functional groups become basic properties material.

  2. Modification of Activated Carbon by Means of Microwave Heating and Its Effects on the Pore Texture and Surface Chemistry

    Directory of Open Access Journals (Sweden)

    Bing Li

    2013-02-01

    Full Text Available Two kinds of typical Activated Carbons (coal based AC and coconut shell based AC were modified in a flow of N0 gas has been carried out using a microwave device operating at 2450 MHz and different input power, instead of a conventional furnace. The samples were analyzed by means of low temperatureN0 adsorption, elemental analysis and Boehm titration. The results show that microwave heating is an effective means of activated carbon modification. The temperature of activated carbon increases rapidly under microwave heating and then gradual increase to a quasi-stationary temperature. The pore texture of activated carbon changes slightly after microwave treatment and the two activated carbons still keep rich pore structure. The oxygen functional groups decompose and evolve with the form of CO and CO2. This in turn gives rise to a significant decrease in oxygen content. These changes of oxygen contents increase as the microwave input power increases. During microwave treatment, a gradual decrease in the surface acidic functional groups is observed. More important, with the removal of the surface acidic groups, the number of the basic group increased gradually, the activated carbon with oxygen functional groups become basic properties material.

  3. Surface textured molybdenum doped zinc oxide thin films prepared for thin film solar cells using pulsed direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.C., E-mail: ielinyc@cc.ncue.edu.tw; Wang, B.L.; Yen, W.T.; Shen, C.H.

    2011-06-01

    In this study, we examined the effect of etching on the electrical properties, transmittance, and scattering of visible light in molybdenum doped zinc oxide, ZnO:Mo (MZO) thin films prepared by pulsed direct current magnetron sputtering. We used two different etching solutions - KOH and HCl - to alter the surface texture of the MZO thin film so that it could trap light. The experimental results showed that an MZO film with a minimum resistivity of about 8.9 x 10{sup -4} {Omega} cm and visible light transitivity of greater than 80% can be obtained without heating at a Mo content of 1.77 wt.%, sputtering power of 100 W, working pressure of 0.4 Pa, pulsed frequency of 10 kHz, and film thickness of 500 nm. To consider the effect of resistivity and optical diffuse transmittance, we performed etching of an 800 nm thick MZO thin film with 0.5 wt.% HCl for 3-6 s at 300 K. Consequently, we obtained a resistivity of 1.74-2.75 x 10{sup -3} {Omega} cm, total transmittance at visible light of 67%-73%, diffuse transmittance at visible light of 25.1%-28.4%, haze value of 0.34-0.42, and thin film surface crater diameters of 220-350 nm.

  4. Scattering patterns of dihedral corner reflectors with impedance surface impedances

    Science.gov (United States)

    Balanis, Constantine A.; Griesser, Timothy; Liu, Kefeng

    The radar cross section patterns of lossy dihedral corner reflectors are calculated using a uniform geometrical theory of diffraction for impedance surfaces. All terms of up to third order reflections are considered for patterns in the principal plane. The surface waves are included whenever they exist for reactive surface impedances. The dihedral corner reflectors examined have right, obtuse, and acute interior angles, and patterns over the entire 360 deg azimuthal plane are calculated. The surface impedances can be different on the four faces of the dihedral corner reflector; however, the surface impedance must be uniform over each face. Computed cross sections are compared with a moment method technique for a dielectric/ferrite absorber coating on a metallic corner reflector. The analysis of the dihedral corner reflector is important because it demonstrates many of the important scattering contributors of complex targets including both interior and exterior wedge diffraction, half-plane diffraction, and dominant multiple reflections and diffractions.

  5. Adsorption of HP Lattice Proteins on Patterned Surfaces

    Science.gov (United States)

    Wilson, Matthew; Shi, Guangjie; Landau, David P.; Li, Ying Wai; Wuest, Thomas

    2014-03-01

    The HP lattice model[2] is a course-grained, yet useful tool for modeling protein sequences where amino acids are treated as either hydrophobic (H) or polar (P) monomers. With the use of Wang-Landau sampling and an efficient set of Monte-Carlo moves[3], HP lattice proteins adsorbed on patterned surfaces are studied. Each substrate is modeled as a periodically bounded pattern of lattice sites that interact with either H or P monomers in the lattice protein, where the energy contributions of the surface are determined by assigned coupling strengths. By analyzing energy degeneracies, along with the thermodynamic and structural quantities of the protein, both the protein folding and surface adsorption can be observed. The adsorption behavior of the lattice proteins on patterned surfaces will be compared to those interacting with uniform surfaces. Research supported by NSF.

  6. The Reliability of Pattern Classification in Bloodstain Pattern Analysis, Part 1: Bloodstain Patterns on Rigid Non-absorbent Surfaces.

    Science.gov (United States)

    Taylor, Michael C; Laber, Terry L; Kish, Paul E; Owens, Glynn; Osborne, Nikola K P

    2016-07-01

    This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non-absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed.

  7. Variations in Surface Texture of the North Polar Residual Cap of Mars

    Science.gov (United States)

    Milkovich, S. M.; Byrne, S.; Russell, P. S.

    2011-01-01

    The northern polar residual cap (NPRC) of Mars is a water ice deposit with a rough surface made up of pits, knobs, and linear depressions on scales of tens of meters. This roughness manifests as a series of bright mounds and dark hollows in visible images; these bright and dark patches have a characteristic wavelength and orientation. Spectral data indicate that the surface of the NPRC is composed of large-grained (and therefore old) water ice. Due to the presence of this old ice, it is thought that the NPRC is in a current state of net loss of material a result potentially at odds with impact crater statistics, which suggest ongoing deposition over the past 10-20 Kyr.

  8. SUPPLEMENTARY COMPARISON - EUROMET.L-S11 comparison on surface texture

    DEFF Research Database (Denmark)

    Koenders, L.; Andreasen, Jan Lasson; De Chiffre, Leonardo

    2004-01-01

    of those used are traced back to SI by national metrology institutes (NMi), which should participate in international comparison to proof the validation of measurement results. Sixteen NMi from the EUROMET region carried out measurements on standards between May 2001 and March 2003. The set of standards......The measurement of roughness of technical surfaces is important in research and for industry. There are a lot of 2D roughness parameters that are defined and standardized by ISO. Calibration standards can be used to calibrate the instruments and ensure traceability to the SI unit of length. Most...... used complied with ISO 5436-1 and consisted of one depth-setting standard of type A, three calibration standards of type C, three standards of type D1 and one standard of type D2. The participants aimed to measure 50 surface roughness parameters. These included the most interesting parameters...

  9. Imaging of surface spin textures on bulk crystals by scanning electron microscopy.

    Science.gov (United States)

    Akamine, Hiroshi; Okumura, So; Farjami, Sahar; Murakami, Yasukazu; Nishida, Minoru

    2016-11-22

    Direct observation of magnetic microstructures is vital for advancing spintronics and other technologies. Here we report a method for imaging surface domain structures on bulk samples by scanning electron microscopy (SEM). Complex magnetic domains, referred to as the maze state in CoPt/FePt alloys, were observed at a spatial resolution of less than 100 nm by using an in-lens annular detector. The method allows for imaging almost all the domain walls in the mazy structure, whereas the visualisation of the domain walls with the classical SEM method was limited. Our method provides a simple way to analyse surface domain structures in the bulk state that can be used in combination with SEM functions such as orientation or composition analysis. Thus, the method extends applications of SEM-based magnetic imaging, and is promising for resolving various problems at the forefront of fields including physics, magnetics, materials science, engineering, and chemistry.

  10. Variations in Surface Texture of the North Polar Residual Cap of Mars

    Science.gov (United States)

    Milkovich, S. M.; Byrne, S.; Russell, P. S.

    2011-01-01

    The northern polar residual cap (NPRC) of Mars is a water ice deposit with a rough surface made up of pits, knobs, and linear depressions on scales of tens of meters. This roughness manifests as a series of bright mounds and dark hollows in visible images; these bright and dark patches have a characteristic wavelength and orientation. Spectral data indicate that the surface of the NPRC is composed of large-grained (and therefore old) water ice. Due to the presence of this old ice, it is thought that the NPRC is in a current state of net loss of material a result potentially at odds with impact crater statistics, which suggest ongoing deposition over the past 10-20 Kyr.

  11. Functional anatomy of the equine temporomandibular joint: Collagen fiber texture of the articular surfaces

    OpenAIRE

    Adams, K.; Schulz-Kornas, E; Arzi, B.; Failing, K.; Vogelsberg, J; Staszyk, C

    2016-01-01

    In the last decade, the equine masticatory apparatus has received much attention. Numerous studies have emphasized the importance of the temporomandibular joint (TMJ) in the functional process of mastication. However, ultrastructural and histological data providing a basis for biomechanical and histopathological considerations are not available. The aim of the present study was to analyze the architecture of the collagen fiber apparatus in the articular surfaces of the equine TMJ to reveal ty...

  12. Surface morphology and physical properties of partially melt textured Mn doped Bi-2223

    Directory of Open Access Journals (Sweden)

    Indu Verma

    2011-09-01

    Full Text Available The samples of Bi2Sr2Ca2Cu3-xMnxO10+δ (x = 0.0 to 0.30 were prepared by the standard solid-state reaction method. The phase identification characteristics of synthesized (HTSC materials were explored through powder X-ray diffractometer reveals that all the samples crystallize in orthorhombic structure with lattice parameters a = 5.4053 Å, b = 5.4110 Å and c = 37.0642 Å up to Mn concentration of x = 0.30. The critical temperature (Tc measured by standard four probe method has been found to depress from 108 K to 70 K as Mn content (x increases from 0.00 to 0.30. The effects of sintering temperature on the surface morphology of Bi2Sr2Ca2Cu3-xMnxO10+δ have also been investigated. The surface morphology investigated through scanning electron microscope and atomic force microscopy (SEM & AFM results that voids are decreasing but grains size increases as the Mn concentration increases besides, nanosphere like structures on the surface of the Mn doped Bi2Sr2Ca2Cu3-xMnxO10+δ (Bi-2223 samples.

  13. The spectral emittance and stability of coatings and textured surfaces for thermophotovoltaic (TPV) radiator applications

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.; Hollenbeck, J.L.

    2000-11-01

    Coatings or surface modifications are needed to improve the surface emissivity of materials under consideration for TPV radiator applications to a value of 0.8 or higher. Vacuum plasma spray coatings (ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, Fe{sub 2}TiO{sub 5}, ZrTiO{sub 4}, ZrO{sub 2} + 8% Y{sub 2}O{sub 3} + 2% HfO{sub 2}, and Al{sub 2}O{sub 3} + TiO{sub 2}) and a chemical vapor deposited coating of rhenium whiskers were used to increase the surface emissivity of refractory metal and nickel-base materials. Emittance measurements following 4000 hours of vacuum annealing at 1100 C show that only the ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, and Al{sub 2}O{sub 3} + TiO{sub 2} coatings have the desired thermal stability, and maintain emissivity values higher than 0.8. These coatings are graybody emitters, and provide a high emissivity value in the wavelength range that is relevant to the TPV cells. The highest emissivity values were observed for the Al{sub 2}O{sub 3} + TiO{sub 2} coatings, with post-anneal values higher than graphite.

  14. Light scattering effect of ITO:Zr/AZO films deposited on periodic textured glass surface morphologies for silicon thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Shahzada Qamar [Sungkyunkwan University, Department of Energy Science, Suwon (Korea, Republic of); COMSATS Institute of Information Technology, Department of Physics, Lahore (Pakistan); Kwon, Gi Duk; Kim, Sunbo; Balaji, Nagarajan; Shin, Chonghoon; Kim, Sangho; Khan, Shahbaz; Pribat, Didier [Sungkyunkwan University, Department of Energy Science, Suwon (Korea, Republic of); Ahn, Shihyun; Le, Anh Huy Tuan; Park, Hyeongsik; Raja, Jayapal; Lee, Youn-Jung [Sungkyunkwan University, College of Information and Communication Engineering, Suwon (Korea, Republic of); Razaq, Aamir [COMSATS Institute of Information Technology, Department of Physics, Lahore (Pakistan); Velumani, S. [Sungkyunkwan University, College of Information and Communication Engineering, Suwon (Korea, Republic of); Department of Electrical Engineering (SEES), Mexico City (Mexico); Yi, Junsin [Sungkyunkwan University, Department of Energy Science, Suwon (Korea, Republic of); Sungkyunkwan University, College of Information and Communication Engineering, Suwon (Korea, Republic of)

    2015-09-15

    Various SF{sub 6}/Ar plasma-textured periodic glass surface morphologies for high transmittance, haze ratio and low sheet resistance of ITO:Zr films are reported. The SF{sub 6}/Ar plasma-textured glass surface morphologies were changed from low aspect ratio to high aspect ratio with the increase in RF power from 500 to 600 W. The micro- and nano-size features of textured glass surface morphologies enhanced the haze ratio in visible as well as NIR wavelength region. Micro-size textured features also influenced the sheet resistance and electrical characteristics of ITO:Zr films due to step coverage. The ITO:Zr/AZO bilayer was used as front TCO electrode for p-i-n amorphous silicon thin film solar cells with current density-voltage characteristics as: V{sub oc} = 875 mV, FF = 70.90 %, J{sub sc} = 11.31 mA/cm{sup 2}, η = 7.02 %. (orig.)

  15. Imaging of surface spin textures on bulk crystals by scanning electron microscopy

    OpenAIRE

    Hiroshi Akamine; So Okumura; Sahar Farjami; Yasukazu Murakami; Minoru Nishida

    2016-01-01

    Direct observation of magnetic microstructures is vital for advancing spintronics and other technologies. Here we report a method for imaging surface domain structures on bulk samples by scanning electron microscopy (SEM). Complex magnetic domains, referred to as the maze state in CoPt/FePt alloys, were observed at a spatial resolution of less than 100 nm by using an in-lens annular detector. The method allows for imaging almost all the domain walls in the mazy structure, whereas the visualis...

  16. Facile stamp patterning method for superhydrophilic/superhydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, Sungnam, E-mail: blueden@postech.ac.kr; Hwang, Woonbong, E-mail: whwang@postech.ac.kr [Department of Mechanical Engineering, POSTECH, Pohang 680-749 (Korea, Republic of)

    2015-11-16

    Patterning techniques are essential to many research fields such as chemistry, biology, medicine, and micro-electromechanical systems. In this letter, we report a simple, fast, and low-cost superhydrophobic patterning method using a superhydrophilic template. The technique is based on the contact stamping of the surface during hydrophobic dip coating. Surface characteristics were measured using scanning electron microscopy and energy-dispersive X-ray spectroscopic analysis. The results showed that the hydrophilic template, which was contacted with the stamp, was not affected by the hydrophobic solution. The resolution study was conducted using a stripe shaped stamp. The patterned line was linearly proportional to the width of the stamp line with a constant narrowing effect. A surface with regions of four different types of wetting was fabricated to demonstrate the patterning performance.

  17. Proceedings of the Second Annual Symposium on Mathematical Pattern Recognition and Image Analysis Program

    Science.gov (United States)

    Guseman, L. F., Jr. (Principal Investigator)

    1984-01-01

    Several papers addressing image analysis and pattern recognition techniques for satellite imagery are presented. Texture classification, image rectification and registration, spatial parameter estimation, and surface fitting are discussed.

  18. High resolution imaging of surface patterns of single bacterial cells

    Energy Technology Data Exchange (ETDEWEB)

    Greif, Dominik; Wesner, Daniel [Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld (Germany); Regtmeier, Jan, E-mail: jan.regtmeier@physik.uni-bielefeld.de [Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld (Germany); Anselmetti, Dario [Experimental Biophysics and Applied Nanoscience, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld (Germany)

    2010-09-15

    We systematically studied the origin of surface patterns observed on single Sinorhizobium meliloti bacterial cells by comparing the complementary techniques atomic force microscopy (AFM) and scanning electron microscopy (SEM). Conditions ranged from living bacteria in liquid to fixed bacteria in high vacuum. Stepwise, we applied different sample modifications (fixation, drying, metal coating, etc.) and characterized the observed surface patterns. A detailed analysis revealed that the surface structure with wrinkled protrusions in SEM images were not generated de novo but most likely evolved from similar and naturally present structures on the surface of living bacteria. The influence of osmotic stress to the surface structure of living cells was evaluated and also the contribution of exopolysaccharide and lipopolysaccharide (LPS) by imaging two mutant strains of the bacterium under native conditions. AFM images of living bacteria in culture medium exhibited surface structures of the size of single proteins emphasizing the usefulness of AFM for high resolution cell imaging.

  19. Wave optical simulation of the light trapping properties of black silicon surface textures.

    Science.gov (United States)

    Bett, Alexander Jürgen; Eisenlohr, Johannes; Höhn, Oliver; Repo, Päivikki; Savin, Hele; Bläsi, Benedikt; Goldschmidt, Jan Christoph

    2016-03-21

    Due to their low reflectivity and effective light trapping properties black silicon nanostructured surfaces are promising front side structures for thin crystalline silicon solar cells. For further optimization of the light trapping effect, particularly in combination with rear side structures, it is necessary to simulate the optical properties of black silicon. Especially, the angular distribution of light in the silicon bulk after passage through the front side structure is relevant. In this paper, a rigorous coupled wave analysis of black silicon is presented, where the black silicon needle shaped structure is approximated by a randomized cone structure. The simulated absorptance agrees well with measurement data. Furthermore, the simulated angular light distribution within the silicon bulk shows that about 70% of the light can be subjected to internal reflection, highlighting the good light trapping properties.

  20. Excimer laser texturing of natural composite polymer surfaces for studying cell-to-substrate specific response

    Science.gov (United States)

    Dinca, V.; Alloncle, P.; Delaporte, P.; Ion, V.; Rusen, L.; Filipescu, M.; Mustaciosu, C.; Luculescu, C.; Dinescu, M.

    2015-10-01

    Surface modifications of biocompatible materials are among the main factors used for enhancing and promoting specific cellular activities (e.g. spreading, adhesion, migration, and differentiation) for various types of medical applications such as implants, microfluidic devices, or tissue engineering scaffolds. In this work an excimer laser at 193 nm was used to fabricate chitosan-collagen roughness gradients. The roughness gradients were obtained in one step by applying single laser pulses and sample tilting. Fourier transform infrared spectroscopy measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectro-ellipsometry (SE) were used for sample characterization. The goal is to determine the optimal morpho-chemical characteristics of these structures for in vitro tailoring of protein adsorption and cell behavior. The response induced by the roughness gradient onto various cell lines (i.e. L 929 fibroblasts, HEP G2 hepatocytes, OLN 93 oligodendrocytes, M63 osteoblasts) and bovine serum albumin (BSA) protein absorption was investigated.

  1. Seals Having Textured Portions for Protection in Space Environments

    Science.gov (United States)

    Daniels, Christopher (Inventor); Garafolo, Nicholas (Inventor)

    2016-01-01

    A sealing construct for a space environment includes a seal-bearing object, a seal on the seal-bearing object, and a seal-engaging object. The seal includes a seal body having a sealing surface, and a textured pattern at the sealing surface, the textured pattern defining at least one shaded channel surface. The seal-engaging object is selectively engaged with the seal-bearing object through the seal. The seal-engaging object has a sealing surface, wherein, when the seal-engaging object is selectively engaged with the seal-bearing object, the sealing surface of the seal-engaging object engages the sealing surface of the seal, and the seal is compressed between the seal-bearing object and the seal-engaging object such that at least one shaded channel surface engages the sealing surface of the seal-engaging object.

  2. Multicomponent Droplet Evaporation on Chemical Micro-Patterned Surfaces

    Science.gov (United States)

    He, Minghao; Liao, Dong; Qiu, Huihe

    2017-02-01

    The evaporation and dynamics of a multicomponent droplet on a heated chemical patterned surface were presented. Comparing to the evaporation process of a multicomponent droplet on a homogenous surface, it is found that the chemical patterned surface can not only enhance evaporation by elongating the contact line, but also change the evaporation process from three regimes for the homogenous surface including constant contact line (CCL) regime, constant contact angle (CCA) regime and mix mode (MM) to two regimes, i.e. constant contact line (CCL) and moving contact line (MCL) regimes. The mechanism of contact line stepwise movement in MCL regimes in the microscopic range is investigated in detail. In addition, an improved local force model on the contact line was employed for analyzing the critical receding contact angles on homogenous and patterned surfaces. The analysis results agree well for both surfaces, and confirm that the transition from CCL to MCL regimes indicated droplet composition changes from multicomponent to monocomponent, providing an important metric to predict and control the dynamic behavior and composition of a multicomponent droplet using a patterned surface.

  3. LOCAL TEXTURE DESCRIPTION FRAMEWORK FOR TEXTURE BASED FACE RECOGNITION

    Directory of Open Access Journals (Sweden)

    R. Reena Rose

    2014-02-01

    Full Text Available Texture descriptors have an important role in recognizing face images. However, almost all the existing local texture descriptors use nearest neighbors to encode a texture pattern around a pixel. But in face images, most of the pixels have similar characteristics with that of its nearest neighbors because the skin covers large area in a face and the skin tone at neighboring regions are same. Therefore this paper presents a general framework called Local Texture Description Framework that uses only eight pixels which are at certain distance apart either circular or elliptical from the referenced pixel. Local texture description can be done using the foundation of any existing local texture descriptors. In this paper, the performance of the proposed framework is verified with three existing local texture descriptors Local Binary Pattern (LBP, Local Texture Pattern (LTP and Local Tetra Patterns (LTrPs for the five issues viz. facial expression, partial occlusion, illumination variation, pose variation and general recognition. Five benchmark databases JAFFE, Essex, Indian faces, AT&T and Georgia Tech are used for the experiments. Experimental results demonstrate that even with less number of patterns, the proposed framework could achieve higher recognition accuracy than that of their base models.

  4. Automated analysis of art object surfaces using time-averaged digital speckle pattern interferometry

    Science.gov (United States)

    Lukomski, Michal; Krzemien, Leszek

    2013-05-01

    Technical development and practical evaluation of a laboratory built, out-of-plane digital speckle pattern interferometer (DSPI) are reported. The instrument was used for non-invasive, non-contact detection and characterization of early-stage damage, like fracturing and layer separation, of painted objects of art. A fully automated algorithm was developed for recording and analysis of vibrating objects utilizing continuous-wave laser light. The algorithm uses direct, numerical fitting or Hilbert transformation for an independent, quantitative evaluation of the Bessel function at every point of the investigated surface. The procedure does not require phase modulation and thus can be implemented within any, even the simplest, DSPI apparatus. The proposed deformation analysis is fast and computationally inexpensive. Diagnosis of physical state of the surface of a panel painting attributed to Nicolaus Haberschrack (a late-mediaeval painter active in Krakow) from the collection of the National Museum in Krakow is presented as an example of an in situ application of the developed methodology. It has allowed the effectiveness of the deformation analysis to be evaluated for the surface of a real painting (heterogeneous colour and texture) in a conservation studio where vibration level was considerably higher than in the laboratory. It has been established that the methodology, which offers automatic analysis of the interferometric fringe patterns, has a considerable potential to facilitate and render more precise the condition surveys of works of art.

  5. Magnetism, spin texture and in-gap states. Atomic specialization at the surface of oxygen-deficient SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Jeschke, Harald O.; Altmeyer, Michaela; Valenti, Roser [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Rozenberg, Marcelo; Gabay, Marc [Laboratoire de Physique des Solides, Bat 510, Universite Paris-Sud, 91405 Orsay (France)

    2016-07-01

    We investigate the electronic structure and spin texture at the (001) surface of SrTiO{sub 3} in the presence of oxygen vacancies by means of ab initio density functional theory (DFT) calculations of slabs. Relativistic non-magnetic DFT calculations exhibit Rashba-like spin winding with a characteristic energy scale ∝ 10 meV. However, when surface magnetism on the Ti ions is included, bands become spin-split with an energy difference ∝ 100 meV at the Γ point. This energy scale is comparable to the observations in SARPES experiments performed on the two-dimensional electronic states confined near the (001) surface of SrTiO{sub 3}. We find the spin polarized state to be the ground state of the system, and while magnetism tends to suppress the effects of the relativistic Rashba interaction, signatures of it are still clearly visible in terms of complex spin textures.

  6. Imaging textural variation in the acoustoelastic coefficient of aluminum using surface acoustic waves.

    Science.gov (United States)

    Ellwood, R; Stratoudaki, T; Sharples, S D; Clark, M; Somekh, M G

    2015-11-01

    Much interest has arisen in nonlinear acoustic techniques because of their reported sensitivity to variations in residual stress, fatigue life, and creep damage when compared to traditional linear ultrasonic techniques. However, there is also evidence that the nonlinear acoustic properties are also sensitive to material microstructure. As many industrially relevant materials have a polycrystalline structure, this could potentially complicate the monitoring of material processes when using nonlinear acoustics. Variations in the nonlinear acoustoelastic coefficient on the same length scale as the microstructure of a polycrystalline sample of aluminum are investigated in this paper. This is achieved by the development of a measurement protocol that allows imaging of the acoustoelastic response of a material across a samples surface at the same time as imaging the microstructure. The development, validation, and limitations of this technique are discussed. The nonlinear acoustic response is found to vary spatially by a large factor (>20) between different grains. A relationship is observed when the spatial variation of the acoustoelastic coefficient is compared to the variation in material microstructure.

  7. Wet-Chemical Surface Texturing of Sputter-Deposited ZnO:Al Films as Front Electrode for Thin-Film Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Xia Yan

    2015-01-01

    Full Text Available Transparent conductive oxides (TCOs play a major role as the front electrodes of thin-film silicon (Si solar cells, as they can provide optical scattering and hence improved photon absorption inside the devices. In this paper we report on the surface texturing of aluminium-doped zinc oxide (ZnO:Al or AZO films for improved light trapping in thin-film Si solar cells. The AZO films are deposited onto soda-lime glass sheets via pulsed DC magnetron sputtering. Several promising AZO texturing methods are investigated using diluted hydrochloric (HCl and hydrofluoric acid (HF, through a two-step etching process. The developed texturing procedure combines the advantages of the HCl-induced craters and the smaller and jagged—but laterally more uniform—features created by HF etching. In the two-step process, the second etching step further enhances the optical haze, while simultaneously improving the uniformity of the texture features created by the HCl etch. The resulting AZO films show large haze values of above 40%, good scattering into large angles, and a surface angle distribution that is centred at around 30°, which is known from the literature to provide efficient light trapping for thin-film Si solar cells.

  8. Texture analysis of collagen second-harmonic generation images based on local difference local binary pattern and wavelets differentiates human skin abnormal scars from normal scars.

    Science.gov (United States)

    Liu, Yao; Zhu, Xiaoqin; Huang, Zufang; Cai, Jianyong; Chen, Rong; Xiong, Shuyuan; Chen, Guannan; Zeng, Haishan

    2015-01-01

    Quantitative methods for noninvasive diagnosis of scars are a challenging issue in medicine. This work aims to implement a texture analysis method for quantitatively discriminating abnormal scars from normal scars based on second-harmonic generation (SHG) images. A local difference local binary pattern (LD-LBP) operator combined with a wavelet transform was explored to extract diagnosis features from scar SHG images that were related to the alteration in collagen morphology. Based on the quantitative parameters including the homogeneity, directional and coarse features in SHG images, the scar collagen SHG images were classified into normal or abnormal scars by a support vector machine classifier in a leave-one-out cross-validation procedure. Our experiments and data analyses demonstrated apparent differences between normal and abnormal scars in terms of their morphological structure of collagen. By comparing with gray level co-occurrence matrix, wavelet transform, and combined basic local binary pattern and wavelet transform with respect to the accuracy and receiver operating characteristic analysis, the method proposed herein was demonstrated to achieve higher accuracy and more reliable classification of SHG images. This result indicated that the extracted texture features with the proposed method were effective in the classification of scars. It could provide assistance for physicians in the diagnostic process.

  9. Surface micro- and nano-texturing of stainless steel by femtosecond laser for the control of cell migration

    Science.gov (United States)

    Martínez-Calderon, M.; Manso-Silván, M.; Rodríguez, A.; Gómez-Aranzadi, M.; García-Ruiz, J. P.; Olaizola, S. M.; Martín-Palma, R. J.

    2016-11-01

    The precise control over the interaction between cells and the surface of materials plays a crucial role in optimizing the integration of implanted biomaterials. In this regard, material surface with controlled topographic features at the micro- and nano-scales has been proved to affect the overall cell behavior and therefore the final osseointegration of implants. Within this context, femtosecond (fs) laser micro/nano machining technology was used in this work to modify the surface structure of stainless steel aiming at controlling cell adhesion and migration. The experimental results show that cells tend to attach and preferentially align to the laser-induced nanopatterns oriented in a specific direction. Accordingly, the laser-based fabrication method here described constitutes a simple, clean, and scalable technique which allows a precise control of the surface nano-patterning process and, subsequently, enables the control of cell adhesion, migration, and polarization. Moreover, since our surface-patterning approach does not involve any chemical treatments and is performed in a single step process, it could in principle be applied to most metallic materials.

  10. Dominant patterns of winter Arctic surface wind variability

    Institute of Scientific and Technical Information of China (English)

    WU Bingyi; John Walsh; LIU Jiping; ZHANG Xiangdong

    2014-01-01

    Dominant statistical patterns of winter Arctic surface wind (WASW) variability and their impacts on Arctic sea ice motion are investigated using the complex vector empirical orthogonal function (CVEOF) method. The results indicate that the leading CVEOF of Arctic surface wind variability, which accounts for 33% of the covariance, is characterized by two different and alternating spatial patterns (WASWP1 and WASWP2). Both WASWP1 and WASWP2 show strong interannual and decadal variations, superposed on their declining trends over past decades. Atmospheric circulation anomalies associated with WASWP1 and WASWP2 exhibit, respectively, equivalent barotropic and some baroclinic characteristics, differing from the Arctic dipole anomaly and the seesaw structure anomaly between the Barents Sea and the Beaufort Sea. On decadal time scales, the decline trend of WASWP2 can be attributed to persistent warming of sea surface temperature in the Greenland—Barents—Kara seas from autumn to winter, relfecting the effect of the Arctic warming. The second CVEOF, which accounts for 18% of the covariance, also contains two different spatial patterns (WASWP3 and WASWP4). Their time evolutions are signiifcantly correlated with the North Atlantic Oscillation (NAO) index and the central Arctic Pattern, respectively, measured by the leading EOF of winter sea level pressure (SLP) north of 70°N. Thus, winter anomalous surface wind pattern associated with the NAO is not the most important surface wind pattern. WASWP3 and WASWP4 primarily relfect natural variability of winter surface wind and neither exhibits an apparent trend that differs from WASWP1 or WASWP2. These dominant surface wind patterns strongly inlfuence Arctic sea ice motion and sea ice exchange between the western and eastern Arctic. Furthermore, the Fram Strait sea ice volume lfux is only signiifcantly correlated with WASWP3. The results demonstrate that surface and geostrophic winds are not interchangeable in terms of

  11. Polymer Brushes as Functional, Patterned Surfaces for Nanobiotechnology.

    Science.gov (United States)

    Welch, M Elizabeth; Xu, Youyong; Chen, Hongjun; Smith, Norah; Tague, Michele E; Abruña, Héctor D; Baird, Barbara; Ober, Christopher K

    2013-01-01

    Polymer brushes have many desirable characteristics such as the ability to tether molecules to a substrate or change the properties of a surface. Patterning of polymer films has been an area of great interest due to the broad range of applications including bio-related and medicinal research. Consequently, we have investigated patterning techniques for polymer brushes which allow for two different functionalities on the same surface. This method has been applied to a biosensor device which requires both polymer brushes and a photosensitizer to be polymerized on a patterned gold substrate. Additionally, the nature of patterned polymer brushes as removable thin films was explored. An etching process has enabled us to lift off very thin membranes for further characterization with the potential of using them as Janus membranes for biological applications.

  12. Nanoscale 2.5-dimensional surface patterning with plasmonic lithography.

    Science.gov (United States)

    Jung, Howon; Park, Changhoon; Oh, Seonghyeon; Hahn, Jae W

    2017-08-29

    We report an extension of plasmonic lithography to nanoscale 2.5-dimensional (2.5D) surface patterning. To obtain the impulse response of a plasmonic lithography system, we described the field distribution of a point dipole source generated by a metallic ridge aperture with a theoretical model using the concepts of quasi-spherical waves and surface plasmon-polaritons. We performed deconvolution to construct an exposure map of a target shape for patterning. For practical applications, we fabricated several nanoscale and microscale structures, such as a cone, microlens array, nanoneedle, and a multiscale structure using the plasmonic lithography system. We verified the possibility of applying plasmonic lithography to multiscale structuring from a few tens of nanometres to a few micrometres in the lateral dimension. We obtained a root-mean-square error of 4.7 nm between the target shape and the patterned shape, and a surface roughness of 11.5 nm.

  13. Classification of Simultaneous Movements using Surface EMG Pattern Recognition

    OpenAIRE

    Young, Aaron J.; Smith, Lauren H.; Rouse, Elliott J.; Hargrove, Levi J.

    2012-01-01

    Advanced upper-limb prostheses capable of actuating multiple degrees of freedom (DOF) are now commercially available. Pattern recognition algorithms that use surface electromyography (EMG) signals show great promise as multi-DOF controllers. Unfortunately, current pattern recognition systems are limited to activate only one degree of freedom at a time. This study introduces a novel classifier based on Bayesian theory to provide classification of simultaneous movements. This approach and two o...

  14. Chemoselective ligand patterning of electroactive surfaces using microfluidics.

    Science.gov (United States)

    Westcott, Nathan P; Yousaf, Muhammad N

    2009-10-01

    To generate model substrates for cell adhesion, we have developed two different biocompatible strategies based on self-assembled monolayers (SAMs) of alkanethiolates on gold terminated with latent ketones and aldehydes. Under spatial control, the hydroquinone and alcohol-terminated SAMs can be oxidized to allow for oxyamine ligand patterning on the surface with microfluidic cassettes. These immobilization strategies were characterized by electrochemistry, fluorescence, and utilizing a cell adhesive peptide, cell patterns were generated.

  15. Analysis of surface soil moisture patterns in agricultural landscapes using empirical orthogonal functions

    Directory of Open Access Journals (Sweden)

    W. Korres

    2009-08-01

    Full Text Available Soil moisture is one of the fundamental variables in hydrology, meteorology and agriculture. Nevertheless, its spatio-temporal patterns in agriculturally used landscapes affected by multiple natural (rainfall, soil, topography etc. and agronomic (fertilisation, soil management etc. factors are often not well known. The aim of this study is to determine the dominant factors governing the spatio-temporal patterns of surface soil moisture in a grassland and an arable land test site within the Rur catchment in Western Germany. Surface soil moisture (0–6 cm has been measured in an approx. 50×50 m grid at 14 and 17 dates (May 2007 to November 2008 in both test sites. To analyse spatio-temporal patterns of surface soil moisture, an Empirical Orthogonal Function (EOF analysis was applied and the results were correlated with parameters derived from topography, soil, vegetation and land management to connect the pattern to related factors and processes. For the grassland test site, the analysis results in one significant spatial structure (first EOF, which explains about 57.5% of the spatial variability connected to soil properties and topography. The weight of the first spatial EOF is stronger on wet days. The highest temporal variability can be found in locations with a high percentage of soil organic carbon (SOC. For the arable land test site, the analysis yields two significant spatial structures, the first EOF, explaining 38.4% of the spatial variability, shows a highly significant correlation to soil properties, namely soil texture. The second EOF, explaining 28.3% of the spatial variability, is connected to differences in land management. The soil moisture in the arable land test site varies more during dry and wet periods on locations with low porosity.

  16. Effect of finishing technique on the microleakage and surface texture of resin-modified glass ionomer restorative materials.

    Science.gov (United States)

    Wilder, A D; Swift, E J; May, K N; Thompson, J Y; McDougal, R A

    2000-07-01

    The purpose of this study was to evaluate the effects of wet and dry finishing/polishing procedures on the microleakage and surface texture of resin-modified glass ionomer (RMGI) restorative materials. Class V cavity preparations were made at the cemento-enamel junction (CEJ) on the buccal and lingual surface of 30 extracted human molars. The teeth were restored in three groups of 10 (20 preparations in each group) using Fuji II LC and Vitremer, both RMGIs, and Fuji II, a capsulated conventional glass ionomer cement (control). One restoration per tooth was finished/polished with copious applications of water and the other was finished/polished without water. All restorations were finished/polished using a sequence of four abrasive disks. Finishing/polishing was initiated according to manufacturers' instructions-immediately after light-curing Fuji II LC and Vitremer, and 15min after placement for Fuji II. The specimens were thermocycled and subjected to a silver nitrate leakage test. Each tooth was sectioned buccolingually and examined with an optical microscope at 40x to determine the extent of microleakage at enamel and dentin margins. The data were subjected to a non-parametric statistical analysis. To evaluate surface roughness after polishing, three disks each of Vitremer and Fuji II LC were fabricated in Teflon molds. One disk of each material was not finished/polished (control). The others were finished/polished using Sof-Lex abrasive disks. One specimen of each material was kept wet during all finishing/polishing procedures, while the other was kept dry. Atomic force microscopy was used to determine the average roughness (R(a)) of the specimens. For each material, microleakage at the enamel margin was very slight. Leakage of the conventional glass ionomer Fuji II was severe at dentin margins. Statistical analysis indicated that both Vitremer and Fuji II LC had significantly less leakage than Fuji II, and that Vitremer had significantly less leakage than Fuji

  17. Droplet impact patterns on inclined surfaces with variable properties

    Science.gov (United States)

    Lockard, Michael; Neitzel, G. Paul; Smith, Marc K.

    2014-11-01

    Bloodstain pattern analysis is used in the investigation of a crime scene to infer the impact velocity and size of an impacting droplet and, from these, the droplet's point and cause of origin. The final pattern is the result of complex fluid mechanical processes involved in the impact and spreading of a blood drop on a surface coupled with the wetting properties of the surface itself. Experiments have been designed to study these processes and the resulting patterns for the case of a single Newtonian water droplet impacting a planar, inclined surface with variable roughness and wetting properties. Results for Reynolds numbers in the range of (9,000 - 27,000) and Weber numbers in the range of (300 - 2,600) will be presented. Transient video images and final impact patterns will be analyzed and compared with results from traditional bloodstain pattern-analysis techniques used by the forensics community. In addition, preliminary work with a new Newtonian blood simulant designed to match the viscosity and surface tension of blood will be presented. Supported by the National Institute of Justice.

  18. An Ontology Design Pattern for Surface Water Features

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Gaurav [Ohio University; Mark, David [University at Buffalo (SUNY); Kolas, Dave [Raytheon BBN Technologies; Varanka, Dalia [U.S. Geological Survey, Rolla, MO; Romero, Boleslo E [University of California, Santa Barbara; Feng, Chen-Chieh [National University of Singapore; Usery, Lynn [U.S. Geological Survey, Rolla, MO; Liebermann, Joshua [Tumbling Walls, LLC; Sorokine, Alexandre [ORNL

    2014-01-01

    Surface water is a primary concept of human experience but concepts are captured in cultures and languages in many different ways. Still, many commonalities can be found due to the physical basis of many of the properties and categories. An abstract ontology of surface water features based only on those physical properties of landscape features has the best potential for serving as a foundational domain ontology. It can then be used to systematically incor-porate concepts that are specific to a culture, language, or scientific domain. The Surface Water ontology design pattern was developed both for domain knowledge distillation and to serve as a conceptual building-block for more complex surface water ontologies. A fundamental distinction is made in this on-tology between landscape features that act as containers (e.g., stream channels, basins) and the bodies of water (e.g., rivers, lakes) that occupy those containers. Concave (container) landforms semantics are specified in a Dry module and the semantics of contained bodies of water in a Wet module. The pattern is imple-mented in OWL, but Description Logic axioms and a detailed explanation is provided. The OWL ontology will be an important contribution to Semantic Web vocabulary for annotating surface water feature datasets. A discussion about why there is a need to complement the pattern with other ontologies, es-pecially the previously developed Surface Network pattern is also provided. Fi-nally, the practical value of the pattern in semantic querying of surface water datasets is illustrated through a few queries and annotated geospatial datasets.

  19. Modeling contact angle hysteresis on chemically patterned and superhydrophobic surfaces.

    Science.gov (United States)

    Kusumaatmaja, H; Yeomans, J M

    2007-05-22

    We investigate contact angle hysteresis on chemically patterned and superhydrophobic surfaces, as the drop volume is quasistatically increased and decreased. We consider both two (cylindrical drops) and three (spherical drops) dimensions using analytical and numerical approaches to minimize the free energy of the drop. In two dimensions, we find, in agreement with other authors, a slip, jump, stick motion of the contact line. In three dimensions, this behavior persists, but the position and magnitude of the contact line jumps are sensitive to the details of the surface patterning. In two dimensions, we identify analytically the advancing and receding contact angles on the different surfaces, and we use numerical insights to argue that these provide bounds for the three-dimensional cases. We present explicit simulations to show that a simple average over the disorder is not sufficient to predict the details of the contact angle hysteresis and to support an explanation for the low contact angle hysteresis of suspended drops on superhydrophobic surfaces.

  20. Improved broadband antireflection in Schottky-like junction of conformal Al-doped ZnO layer on chemically textured Si surfaces

    Science.gov (United States)

    Saini, C. P.; Barman, A.; Kumar, M.; Sahoo, P. K.; Som, T.; Kanjilal, A.

    2014-09-01

    Chemically textured Si with improved absorption in the complete range of solar spectrum is investigated by ultraviolet/visible/near-infrared (UV/Vis/NIR) spectroscopy, showing an average specular reflectance of ˜0.4% in the wavelength of 500-3000 nm. The pyramidal structures on such solar-blind Si can reduce the reflectance further below 0.1% in the UV region by conformal growth of granular Al-doped ZnO (AZO) films. X-ray diffraction analyses suggest the growth of polycrystalline AZO on faceted-Si. Moreover, marginal increase in electrical conductivity of AZO is found on textured surfaces, whereas rise in leakage current in Schottky-like Ag/AZO/Si/Ag heterostructure devices is noticed with increasing Si surface area.

  1. Emotional effects of dynamic textures

    NARCIS (Netherlands)

    Toet, A.; Henselmans, M.; Lucassen, M.P.; Gevers, T.

    2011-01-01

    This study explores the effects of various spatiotemporal dynamic texture characteristics on human emotions. The emotional experience of auditory (eg, music) and haptic repetitive patterns has been studied extensively. In contrast, the emotional experience of visual dynamic textures is still largely

  2. Extracting Canopy Surface Texture from Airborne Laser Scanning Data for the Supervised and Unsupervised Prediction of Area-Based Forest Characteristics

    Directory of Open Access Journals (Sweden)

    Mikko T. Niemi

    2016-07-01

    Full Text Available Area-based analyses of airborne laser scanning (ALS data are an established approach to obtain wall-to-wall predictions of forest characteristics for vast areas. The analyses of sparse data in particular are based on the height value distributions, which do not produce optimal information on the horizontal forest structure. We evaluated the complementary potential of features quantifying the textural variation of ALS-based canopy height models (CHMs for both supervised (linear regression and unsupervised (k-Means clustering analyses. Based on a comprehensive literature review, we identified a total of four texture analysis methods that produced rotation-invariant features of different order and scale. The CHMs and the textural features were derived from practical sparse-density, leaf-off ALS data originally acquired for ground elevation modeling. The features were extracted from a circular window of 254 m2 and related with boreal forest characteristics observed from altogether 155 field sample plots. Features based on gray-level histograms, distribution of forest patches, and gray-level co-occurrence matrices were related with plot volume, basal area, and mean diameter with coefficients of determination (R2 of up to 0.63–0.70, whereas features that measured the uniformity of local binary patterns of the CHMs performed poorer. Overall, the textural features compared favorably with benchmark features based on the point data, indicating that the textural features contain additional information useful for the prediction of forest characteristics. Due to the developed processing routines for raster data, the CHM features may potentially be extracted with a lower computational burden, which promotes their use for applications such as pre-stratification or guiding the field plot sampling based solely on ALS data.

  3. Climate and soil texture influence patterns of forb species richness and composition in big sagebrush plant communities across their spatial extent in the western US

    Science.gov (United States)

    Pennington, Victoria E.; Palmquist, Kyle A.; Bradford, John B.; Lauenroth, William K.

    2017-01-01

    Article for outlet: Plant Ecology. Abstract: Big sagebrush (Artemisia tridentata Nutt.) plant communities are widespread non-forested drylands in western North American and similar to all shrub steppe ecosystems world-wide are composed of a shrub overstory layer and a forb and graminoid understory layer. Forbs account for the majority of plant species diversity in big sagebrush plant communities and are important for ecosystem function. Few studies have explored the geographic patterns of forb species richness and composition and their relationships with environmental variables in these communities. Our objectives were to examine the small and large-scale spatial patterns in forb species richness and composition and the influence of environmental variables. We sampled forb species richness and composition along transects at 15 field sites in Colorado, Idaho, Montana, Nevada, Oregon, Utah, and Wyoming, built species-area relationships to quantify differences in forb species richness at sites, and used Principal Components Analysis and nonmetric multidimensional scaling to identify relationships among environmental variables and forb species richness and composition. We found that species richness was most strongly correlated with soil texture, while species composition was most related to climate. The combination of climate and soil texture influences water availability, with important consequences for forb species richness and composition, which suggests climate-change induced modification of soil water availability may have important implications for plant species diversity in the future. Our paper is the first to our knowledge to examine forb biodiversity patterns in big sagebrush ecosystems in relation to environmental factors across the big sagebrush region.

  4. Self-organized surface ripple pattern formation by ion implantation

    Science.gov (United States)

    Hofsäss, Hans; Zhang, Kun; Bobes, Omar

    2016-10-01

    Ion induced ripple pattern formation on solid surfaces has been extensively studied in the past and the theories describing curvature dependent ion erosion as well as redistribution of recoil atoms have been very successful in explaining many features of the pattern formation. Since most experimental studies use noble gas ion irradiation, the incorporation of the ions into the films is usually neglected. In this work we show that the incorporation or implantation of non-volatile ions also leads to a curvature dependent term in the equation of motion of a surface height profile. The implantation of ions can be interpreted as a negative sputter yield; and therefore, the effect of ion implantation is opposite to the one of ion erosion. For angles up to about 50°, implantation of ions stabilizes the surface, whereas above 50°, ion implantation contributes to the destabilization of the surface. We present simulations of the curvature coefficients using the crater function formalism and we compare the simulation results to the experimental data on the ion induced pattern formation using non-volatile ions. We present several model cases, where the incorporation of ions is a crucial requirement for the pattern formation.

  5. Surface tracking in polymers: a pattern discrimination technique using fractals

    Energy Technology Data Exchange (ETDEWEB)

    Rajini, V; Kumar, K Udaya [Department of High Voltage Engineering, College of Engineering Guindy, Anna University, Chennai-600025 (India)

    2006-08-21

    The geometrical patterns of dielectric breakdown like electrical trees, surface discharges and lightning are known to be fractal in nature. These fractal patterns can be analysed numerically using fractal dimensions and lacunarity. Surface tracking occurring in high voltage insulation systems is a very complex phenomenon and more so the shapes of tracking patterns. It has been fairly well established that the shapes and the underlying parameters causing tracking have a one-to-one correspondence and therefore methods to describe and quantify these patterns must be explored. This contribution reports preliminary results of such a study wherein two-dimensional (2D) tracking patterns of gamma irradiated ethylene propylene diene monomer (EPDM) were analysed and found to possess fairly reasonable pattern discriminating abilities. This approach appears promising and further research is essential before any long-term predictions can be made. It is also interesting to note that the ac tracking resistance of EPDM decreases with an increase in the radiation dose. The erosion depth affected by radiation was also studied.

  6. Fractal patterns applied to implant surface: definitions and perspectives.

    Science.gov (United States)

    Dohan Ehrenfest, David M

    2011-10-01

    Fractal patterns are frequently found in nature, but they are difficult to reproduce in artificial objects such as implantable materials. In this article, a definition of the concept of fractals for osseointegrated surfaces is suggested, based on the search for quasi-self-similarity on at least 3 scales of investigation: microscale, nanoscale, and atomic/crystal scale. Following this definition, the fractal dimension of some surfaces may be defined (illustrated here with the Intra-Lock Ossean surface). However the biological effects of this architecture are still unknown and should be examined carefully in the future.

  7. Plasma-nitriding assisted micro-texturing into stainless steel molds

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2015-01-01

    Full Text Available Micro-texturing has grown up to be one of the most promising procedures. This related application required for large-area, fine micro-texturing onto the stainless steel mold materials. A new method other than laser-machining, micro-milling or micro-EDM was awaited for further advancement of this micro-texturing. In the present paper, a plasma nitriding assisted micro-texturing was developed to make various kinds of micro-patterns onto the martensitic stainless steels. First, original patterns were printed onto the surface of substrate by using the ink-jet printer. Then, the masked substrate was subjected to high density plasma nitriding; the un-masked surfaces were nitrided to have higher hardness. This nitrided substrate was further treated by sand-blasting to selectively dig the soft, masked surfaces. Finally, the micro-patterned martensitic stainless steel substrate was fabricated as a mold to duplicate these micro-patterns onto the work materials. The spatial resolution and depth profile controllability of this plasma nitriding assisted micro-texturing was investigated for variety of initial micro-patterns. The original size and dimension of initial micro-patterns were precisely compared with the three dimensional geometry of micro-textures after blasting treatment. The plastic cover case for smart cellular phones was employed to demonstrate how useful this processing is in practice.

  8. Computerized analysis of interstitial lung diseases on chest radiographs based on lung texture, geometric-pattern features, and artificial neural networks

    Science.gov (United States)

    Ishida, Takayuki; Katsuragawa, Shigehiko; Nakamura, Katsumi; Ashizawa, Kazuto; MacMahon, Heber; Doi, Kunio

    2002-05-01

    For computerized detection of interstitial lung disease on chest radiographs, we developed three different methods: texture analysis based on the Fourier transform, geometric- pattern feature analysis, and artificial neural network (ANN) analysis of image data. With these computer-aided diagnostic methods, quantitative measures can be obtained. To improve the diagnostic accuracy, we investigated combined classification schemes by using the results obtained with the three methods for distinction between normal and abnormal chest radiographs with interstitial opacities. The sensitivities of texture analysis, geometric analysis, and ANN analysis were 88.0+/- 1.6%, 91.0+/- 2.6%, and 87.5+/- 1.9%, respectively, at a specificity of 90.0%, whereas the sensitivity of a combined classification scheme with the logical OR operation was improved to 97.1%+/- 1.5% at the same specificity of 90.0%. The combined scheme can achieve higher accuracy than the individual methods for distinction between normal and abnormal cases with interstitial opacities.

  9. Unconventional spin texture of a topologically nontrivial semimetal Sb(110)

    DEFF Research Database (Denmark)

    Strózecka, A.; Eiguren, A.; Bianchi, Marco;

    2012-01-01

    of Sb(110). The existence of the unconventional spin texture is corroborated by the investigations of the electron scattering on this surface. The charge interference patterns formed around single scattering impurities, imaged by scanning tunneling microscopy, reveal the absence of direct backscattering...

  10. STUDY ON THE TEXTURE OF A FRICTION STIR WELDED Mg-Al-Ca ALLOY

    Institute of Scientific and Technical Information of China (English)

    D.T. Zhang; M. Suzuki; K. Maruyama

    2006-01-01

    Macro-texture of an Mg-Al-Ca alloy prepared by friction stir welding (FSW) was investigated through pole figure measurement and X-ray diffraction (XRD) pattern analysis. It was found that at the top and bottom surfaces of friction stir zone (FSZ), (0002) basal planes of magnesium tend to be arranged parallel to the plate surface. In the cross section of FSZ, no obvious texture had evolved and (0002) basal planes showed a random distribution.

  11. Electrochemically Inducible Surfaces for Patterning Two Distinct Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Inseong; Yeo, Woon-Seok [Konkuk University,Seoul (Korea, Republic of)

    2016-04-15

    Herein, we report on a new multicomponent patterning method based on electrochemically inducible self-assembled monolayers on gold. Two different masked functional groups on monolayers are activated to give amine and acetylene moieties through electrochemical activations at negative potential and positive potential, respectively. The resulting amine and acetylene groups are further used as chemical handles for incorporation of ligand molecules via well-known chemoselective conjugation reactions such as amine-specific conjugation chemistry and click reaction. The chemical conversions of masked functional groups to amine and acetylene groups were characterized by cyclic voltammetry. We demonstrated the orthogonal immobilization of two fluorescent dyes on the patterned surface along the patterned features. Our strategy can provide a useful platform technology for the preparation of multicomponent ligand-patterned substrates with various advantages such as chemical flexibility, mild reaction conditions, and high yields of two orthogonal chemical reactions of amine-specific conjugation and click reaction.

  12. The Development of Laser Texturing and Laser Strength System of Roller Surface%轧辊表面激光毛化/强化系统的研制

    Institute of Scientific and Technical Information of China (English)

    钟如涛; 牟文广; 王靓; 莫衡阳

    2013-01-01

    The system used to laser texturing and laser strength on roller surface was developed,This was composed of IPG5000 fiber laser,texturing system,strength system,processing machine and control system,The technology of Chopping disc,prism and the vibration mirror were used,The integration technology of laser hardening function and laser texturing function and disordered texturing technology were solved.The results show that the system has higher precision,stable and reliable.The system is suitable for laser texturing and laser strengthen for roller of Less than 800 mm in diameter and less than 5 500 mm in length or flat workpieces of less than 5 500 mm in length.%研制开发了轧辊表面激光毛化/强化组合系统,此系统由IPG 5000光纤激光器、毛化系统、强化系统、加工机床和控制系统组成,采用了斩光盘、棱镜组合以及振镜技术,解决了激光强化和激光毛化功能的集成以及无序毛化等难点问题.结果表明:此系统精度高,性能稳定、可靠;适用于直径小于800 mm,长度小于5 500 mm轧辊或长度小于5 500ram平面工件的激光毛化和激光强化.

  13. Change of texture, microdeformation and hardness in surface layer of TiNi alloy depending on the number of pulses of electron beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Meisner, L. L., E-mail: llm@ispms.tsc.ru; Meisner, S. N., E-mail: msn@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Markov, A. B., E-mail: a.markov@hq.tsc.ru; Yakovlev, E. V., E-mail: yakovev@lve.hcei.tsc.ru; Ozur, G. E., E-mail: ozur@lve.hcei.tsc.ru [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); Rotshtein, V. P., E-mail: vrotshtein@yahoo.com [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Tomsk State Pedagogical University, Tomsk, 634050 (Russian Federation); Mironov, Yu. P., E-mail: myp@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    This work comprises a study of the influence of the pulse number of low-energy high-current electron beam (LEHCEB) exposure on the value and character of distribution of residual elastic stresses, texturing effects and the relationship between structural-phase states and physical and mechanical properties of the modified surface layers of TiNi alloy. LEHCEB processing of the surface of TiNi samples was carried out using a RITM-SP [3] installation. Energy density of electron beam was constant at E{sub s} = 3.9 ± 0.5 J/cm{sup 2}; pulse duration was 2.8 ± 0.3 μs. The number of pulses in the series was changeable, (n = 2–128). It was shown that as the result of multiple LEHCEB processing of TiNi samples, hierarchically organized multilayer structure is formed in the surface layer. The residual stress field of planar type is formed in the modified surface layer as following: in the direction of the normal to the surface the strain component ε{sub ⊥} < 0 (compressing strain), and in a direction parallel to the surface, the strain component ε{sub ||} > 0 (tensile deformation). Texturing effects and the level of residual stresses after LEHCEB processing of TiNi samples with equal energy density of electron beam (∼3.8 J/cm{sup 2}) depend on the number of pulses and increase with the rise of n > 10.

  14. CHF Enhancement by Surface Patterning based on Hydrodynamic Instability Model

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Han; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    If the power density of a device exceeds the CHF point, bubbles and vapor films will be covered on the whole heater surface. Because vapor films have much lower heat transfer capabilities compared to the liquid layer, the temperature of the heater surface will increase rapidly, and the device could be damaged due to the heater burnout. Therefore, the prediction and the enhancement of the CHF are essential to maximizing the efficient heat removal region. Numerous studies have been conducted to describe the CHF phenomenon, such as hydrodynamic instability theory, macrolayer dryout theory, hot/dry spot theory, and bubble interaction theory. The hydrodynamic instability model, proposed by Zuber, is the predominant CHF model that Helmholtz instability attributed to the CHF. Zuber assumed that the Rayleigh-Taylor (RT) instability wavelength is related to the Helmholtz wavelength. Lienhard and Dhir proposed a CHF model that Helmholtz instability wavelength is equal to the most dangerous RT wavelength. In addition, they showed the heater size effect using various heater surfaces. Lu et al. proposed a modified hydrodynamic theory that the Helmholtz instability was assumed to be the heater size and the area of the vapor column was used as a fitting factor. The modified hydrodynamic theories were based on the change of Helmholtz wavelength related to the RT instability wavelength. In the present study, the change of the RT instability wavelength, based on the heater surface modification, was conducted to show the CHF enhancement based on the heater surface patterning in a plate pool boiling. Sapphire glass was used as a base heater substrate, and the Pt film was used as a heating source. The patterning surface was based on the change of RT instability wavelength. In the present work the study of the CHF was conducted using bare Pt and patterned heating surfaces.

  15. [Visual Texture Agnosia in Humans].

    Science.gov (United States)

    Suzuki, Kyoko

    2015-06-01

    Visual object recognition requires the processing of both geometric and surface properties. Patients with occipital lesions may have visual agnosia, which is impairment in the recognition and identification of visually presented objects primarily through their geometric features. An analogous condition involving the failure to recognize an object by its texture may exist, which can be called visual texture agnosia. Here we present two cases with visual texture agnosia. Case 1 had left homonymous hemianopia and right upper quadrantanopia, along with achromatopsia, prosopagnosia, and texture agnosia, because of damage to his left ventromedial occipitotemporal cortex and right lateral occipito-temporo-parietal cortex due to multiple cerebral embolisms. Although he showed difficulty matching and naming textures of real materials, he could readily name visually presented objects by their contours. Case 2 had right lower quadrantanopia, along with impairment in stereopsis and recognition of texture in 2D images, because of subcortical hemorrhage in the left occipitotemporal region. He failed to recognize shapes based on texture information, whereas shape recognition based on contours was well preserved. Our findings, along with those of three reported cases with texture agnosia, indicate that there are separate channels for processing texture, color, and geometric features, and that the regions around the left collateral sulcus are crucial for texture processing.

  16. Vibrations and spatial patterns in biomimetic surfaces: using the shark-skin effect to control blood clotting.

    Science.gov (United States)

    Ramachandran, Rahul; Maani, Nazanin; Rayz, Vitaliy L; Nosonovsky, Michael

    2016-08-01

    We study the effect of small-amplitude fast vibrations and small-amplitude spatial patterns on various systems involving wetting and liquid flow, such as superhydrophobic surfaces, membranes and flow pipes. First, we introduce a mathematical method of averaging the effect of small spatial and temporal patterns and substituting them with an effective force. Such an effective force can change the equilibrium state of a system as well as a phase state, leading to surface texture-induced and vibration-induced phase control. Vibration and patterns can effectively jam holes in vessels with liquid, separate multi-phase flow, change membrane properties, result in propulsion and locomotion and lead to many other multi-scale, nonlinear effects including the shark-skin effect. We discuss the application of such effects to blood flow for novel biomedical 'haemophobic' applications which can prevent blood clotting and thrombosis by controlling the surface pattern at a wall of a vessel (e.g. a catheter or stent).This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'.

  17. Combinatorial design of textured mechanical metamaterials.

    Science.gov (United States)

    Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin

    2016-07-28

    The structural complexity of metamaterials is limitless, but, in practice, most designs comprise periodic architectures that lead to materials with spatially homogeneous features. More advanced applications in soft robotics, prosthetics and wearable technology involve spatially textured mechanical functionality, which requires aperiodic architectures. However, a naive implementation of such structural complexity invariably leads to geometrical frustration (whereby local constraints cannot be satisfied everywhere), which prevents coherent operation and impedes functionality. Here we introduce a combinatorial strategy for the design of aperiodic, yet frustration-free, mechanical metamaterials that exhibit spatially textured functionalities. We implement this strategy using cubic building blocks-voxels-that deform anisotropically, a local stacking rule that allows cooperative shape changes by guaranteeing that deformed building blocks fit together as in a three-dimensional jigsaw puzzle, and three-dimensional printing. These aperiodic metamaterials exhibit long-range holographic order, whereby the two-dimensional pixelated surface texture dictates the three-dimensional interior voxel arrangement. They also act as programmable shape-shifters, morphing into spatially complex, but predictable and designable, shapes when uniaxially compressed. Finally, their mechanical response to compression by a textured surface reveals their ability to perform sensing and pattern analysis. Combinatorial design thus opens up a new avenue towards mechanical metamaterials with unusual order and machine-like functionalities.

  18. Combinatorial design of textured mechanical metamaterials

    Science.gov (United States)

    Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin

    2016-07-01

    The structural complexity of metamaterials is limitless, but, in practice, most designs comprise periodic architectures that lead to materials with spatially homogeneous features. More advanced applications in soft robotics, prosthetics and wearable technology involve spatially textured mechanical functionality, which requires aperiodic architectures. However, a naive implementation of such structural complexity invariably leads to geometrical frustration (whereby local constraints cannot be satisfied everywhere), which prevents coherent operation and impedes functionality. Here we introduce a combinatorial strategy for the design of aperiodic, yet frustration-free, mechanical metamaterials that exhibit spatially textured functionalities. We implement this strategy using cubic building blocks—voxels—that deform anisotropically, a local stacking rule that allows cooperative shape changes by guaranteeing that deformed building blocks fit together as in a three-dimensional jigsaw puzzle, and three-dimensional printing. These aperiodic metamaterials exhibit long-range holographic order, whereby the two-dimensional pixelated surface texture dictates the three-dimensional interior voxel arrangement. They also act as programmable shape-shifters, morphing into spatially complex, but predictable and designable, shapes when uniaxially compressed. Finally, their mechanical response to compression by a textured surface reveals their ability to perform sensing and pattern analysis. Combinatorial design thus opens up a new avenue towards mechanical metamaterials with unusual order and machine-like functionalities.

  19. The reliance of insolation pattern on surface aspect

    Science.gov (United States)

    Saad, N. Md; Hamid, J. R. Abdul; Mohd Suldi, A.

    2014-02-01

    The Sun's radiated energy is an important source in realizing the green technology concept construction. When interacting with the atmosphere and objects on the Earth's surface incoming solar radiation (insolation) will create insolation patterns that are ambiguous and as a result need to be investigated further. This paper explores the insolation pattern and ambiguities against topographic surfaces in the context of direct, diffuse, and reflectance irradiance. The topography is modeled from LiDAR data as Digital Surface Model (DSM) and Digital Terrain Model (DTM). The generated DSM and DTM were converted to Triangular Irregular Network (TIN) format within the Arc GIS environment before the insolation pattern could be visualized. The slope and aspect of the topography has an impact on the insolation which is the emphasis of this paper. The main outcome from the study is the insolation map and plots of relationship between the insolation and surface aspect. The findings from this study should contribute to the sustainable practices of green building technology.

  20. Nanoscale patterning, macroscopic reconstruction, and enhanced surface stress by organic adsorption on vicinal surfaces

    Science.gov (United States)

    Pollinger, Florian; Schmitt, Stefan; Sander, Dirk; Tian, Zhen; Kirschner, Jürgen; Vrdoljak, Pavo; Stadler, Christoph; Maier, Florian; Marchetto, Helder; Schmidt, Thomas; Schöll, Achim; Umbach, Eberhard

    2017-01-01

    Self-organization is a promising method within the framework of bottom-up architectures to generate nanostructures in an efficient way. The present work demonstrates that self-organization on the length scale of a few to several tens of nanometers can be achieved by a proper combination of a large (organic) molecule and a vicinal metal surface if the local bonding of the molecule on steps is significantly stronger than that on low-index surfaces. In this case thermal annealing may lead to large mass transport of the subjacent substrate atoms such that nanometer-wide and micrometer-long molecular stripes or other patterns are being formed on high-index planes. The formation of these patterns can be controlled by the initial surface orientation and adsorbate coverage. The patterns arrange self-organized in regular arrays by repulsive mechanical interactions over long distances accompanied by a significant enhancement of surface stress. We demonstrate this effect using the planar organic molecule PTCDA as adsorbate and Ag(10 8 7) and Ag(775) surfaces as substrate. The patterns are directly observed by STM, the formation of vicinal surfaces is monitored by high-resolution electron diffraction, the microscopic surface morphology changes are followed by spectro-microscopy, and the macroscopic changes of surface stress are measured by a cantilever bending method. The in situ combination of these complementary techniques provides compelling evidence for elastic interaction and a significant stress contribution to long-range order and nanopattern formation.

  1. Application des ondelettes à l'analyse de texture et à l'inspection de surface industrielle

    Science.gov (United States)

    Wolf, D.; Husson, R.

    1993-11-01

    This paper presents a method of texture analysis based on multiresolution wavelets analysis. We discuss the problem of theoretical and experimental choice of the wavelet. Statistical modelling of wavelet images is treated and it results in considering statistical distribution to be a generalized Gaussian law. An algorithm for texture classification is developed with respect of the variances of different wavelet images. An industrial application of this algorithm illustrates its quality and proves its aptitude for automation of certain tasks in industrial control. Nous présentons une méthode d'analyse de texture fondée sur l'analyse multirésolution par ondelettes. Nous discutons du problème du choix théorique et expérimental de l'ondelette. Le problème de la modélisation statistique des images d'ondelettes est traité et aboutit à considérer la distribution statistique comme une loi de Gauss généralisée. Un algorithme de classification de texture est construit à l'aide de la variance des différentes images d'ondelettes. Enfin, une application industrielle de cet algorithme illustre ses qualités et démontre son aptitude à l'automatisation de certaines tâches de contrôle industriel.

  2. Feature-aware natural texture synthesis

    KAUST Repository

    Wu, Fuzhang

    2014-12-04

    This article presents a framework for natural texture synthesis and processing. This framework is motivated by the observation that given examples captured in natural scene, texture synthesis addresses a critical problem, namely, that synthesis quality can be affected adversely if the texture elements in an example display spatially varied patterns, such as perspective distortion, the composition of different sub-textures, and variations in global color pattern as a result of complex illumination. This issue is common in natural textures and is a fundamental challenge for previously developed methods. Thus, we address it from a feature point of view and propose a feature-aware approach to synthesize natural textures. The synthesis process is guided by a feature map that represents the visual characteristics of the input texture. Moreover, we present a novel adaptive initialization algorithm that can effectively avoid the repeat and verbatim copying artifacts. Our approach improves texture synthesis in many images that cannot be handled effectively with traditional technologies.

  3. Spatial and temporal codes mediate the tactile perception of natural textures.

    Science.gov (United States)

    Weber, Alison I; Saal, Hannes P; Lieber, Justin D; Cheng, Ju-Wen; Manfredi, Louise R; Dammann, John F; Bensmaia, Sliman J

    2013-10-15

    When we run our fingers over the surface of an object, we acquire information about its microgeometry and material properties. Texture information is widely believed to be conveyed in spatial patterns of activation evoked across one of three populations of cutaneous mechanoreceptive afferents that innervate the fingertips. Here, we record the responses evoked in individual cutaneous afferents in Rhesus macaques as we scan a diverse set of natural textures across their fingertips using a custom-made rotating drum stimulator. We show that a spatial mechanism can only account for the processing of coarse textures. Information about most natural textures, however, is conveyed through precise temporal spiking patterns in afferent responses, driven by high-frequency skin vibrations elicited during scanning. Furthermore, these texture-specific spiking patterns predictably dilate or contract in time with changes in scanning speed; the systematic effect of speed on neuronal activity suggests that it can be reversed to achieve perceptual constancy across speeds. The proposed temporal coding mechanism involves converting the fine spatial structure of the surface into a temporal spiking pattern, shaped in part by the mechanical properties of the skin, and ascribes an additional function to vibration-sensitive mechanoreceptive afferents. This temporal mechanism complements the spatial one and greatly extends the range of tangible textures. We show that a combination of spatial and temporal mechanisms, mediated by all three populations of afferents, accounts for perceptual judgments of texture.

  4. Analysis of surface soil moisture patterns in agricultural landscapes using Empirical Orthogonal Functions

    Directory of Open Access Journals (Sweden)

    W. Korres

    2010-05-01

    Full Text Available Soil moisture is one of the fundamental variables in hydrology, meteorology and agriculture. Nevertheless, its spatio-temporal patterns in agriculturally used landscapes that are affected by multiple natural (rainfall, soil, topography etc. and agronomic (fertilisation, soil management etc. factors are often not well known. The aim of this study is to determine the dominant factors governing the spatio-temporal patterns of surface soil moisture in a grassland and an arable test site that are located within the Rur catchment in Western Germany. Surface soil moisture (0–6 cm was measured in an approx. 50×50 m grid during 14 and 17 measurement campaigns (May 2007 to November 2008 in both test sites. To analyse the spatio-temporal patterns of surface soil moisture, an Empirical Orthogonal Function (EOF analysis was applied and the results were correlated with parameters derived from topography, soil, vegetation and land management to link the patterns to related factors and processes. For the grassland test site, the analysis resulted in one significant spatial structure (first EOF, which explained 57.5% of the spatial variability connected to soil properties and topography. The statistical weight of the first spatial EOF is stronger on wet days. The highest temporal variability can be found in locations with a high percentage of soil organic carbon (SOC. For the arable test site, the analysis resulted in two significant spatial structures, the first EOF, which explained 38.4% of the spatial variability, and showed a highly significant correlation to soil properties, namely soil texture and soil stone content. The second EOF, which explained 28.3% of the spatial variability, is linked to differences in land management. The soil moisture in the arable test site varied more strongly during dry and wet periods at locations with low porosity. The method applied is capable of identifying the dominant parameters controlling spatio-temporal patterns of

  5. Curvature-induced symmetry breaking determines elastic surface patterns.

    Science.gov (United States)

    Stoop, Norbert; Lagrange, Romain; Terwagne, Denis; Reis, Pedro M; Dunkel, Jörn

    2015-03-01

    Symmetry-breaking transitions associated with the buckling and folding of curved multilayered surfaces-which are common to a wide range of systems and processes such as embryogenesis, tissue differentiation and structure formation in heterogeneous thin films or on planetary surfaces-have been characterized experimentally. Yet owing to the nonlinearity of the underlying stretching and bending forces, the transitions cannot be reliably predicted by current theoretical models. Here, we report a generalized Swift-Hohenberg theory that describes wrinkling morphology and pattern selection in curved elastic bilayer materials. By testing the theory against experiments on spherically shaped surfaces, we find quantitative agreement with analytical predictions for the critical curves separating labyrinth, hybrid and hexagonal phases. Furthermore, a comparison to earlier experiments suggests that the theory is universally applicable to macroscopic and microscopic systems. Our approach builds on general differential-geometry principles and can thus be extended to arbitrarily shaped surfaces.

  6. Enhancement of light extraction efficiency of vertical LED with patterned graphene as current spreading layer

    Science.gov (United States)

    Singh, Sumitra; Sai Nandini, Annam Deepthi; Pal, Suchandan; Dhanavantri, Chenna

    2016-01-01

    In this paper we report an optimised pattern of surface textured graphene current spreading layer (CSL) for the enhancement of light extraction efficiency (LEE) in InGaN/GaN vertical light emitting diodes (V-LEDs). It is found that by texturing graphene surface LEE improves drastically. This improvement is attributed to better current spreading of graphene and increased random and multiple scattering of light through textured surfaces. Simulation results illustrate that V-LEDs with surface textured (hexagonal pattern) ITO as CSL shows threefold improvement in light extraction efficiency compared to V-LEDs with no surface texturing on ITO CSL. Further, LEE of V-LEDs having patterned graphene CSL is compared with that for indium tin oxide (ITO) CSL. V-LEDs with optimised hexagonal patterning on graphene CSL shows 13.42% enhancement of LEE compared to that of LED with hexagonal patterning on ITO surface.

  7. Using Pattern Search Methods for Surface Structure Determinationof Nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhengji; Meza, Juan; Van Hove, Michel

    2006-06-09

    Atomic scale surface structure plays an important roleindescribing many properties of materials, especially in the case ofnanomaterials. One of the most effective techniques for surface structuredetermination is low-energy electron diffraction (LEED), which can beused in conjunction with optimization to fit simulated LEED intensitiesto experimental data. This optimization problem has a number ofcharacteristics that make it challenging: it has many local minima, theoptimization variables can be either continuous or categorical, theobjective function can be discontinuous, there are no exact analyticderivatives (and no derivatives at all for categorical variables), andfunction evaluations are expensive. In this study, we show how to apply aparticular class of optimization methods known as pattern search methodsto address these challenges. These methods donot explicitly usederivatives, and are particularly appropriate when categorical variablesare present, an important feature that has not been addressed in previousLEED studies. We have found that pattern search methods can produceexcellent results, compared to previously used methods, both in terms ofperformance and locating optimal results.

  8. A new method for patterning azopolymer thin film surfaces

    Science.gov (United States)

    Sorkhabi, Sh. Golghasemi; Barille, R.; Ahmadi-Kandjani, S.; Zielinska, S.; Ortyl, E.

    2017-04-01

    We present a simple bottom-up approach via an incoherent unpolarized illumination and the choice of a solvent-droplet-induced-dewetting method to photoinduce nano doughnuts on the surface of azopolymer thin films. We demonstrate that doughnut-shaped nanostructures can be formed and tailored with a wide range of typical sizes, thus providing a rich field of applications using surface photo-patterning. Furthermore, due to the presence of highly photoactive azobenzene derivative in the material, illumination of these nanostructures by a polarized laser light shows the possibility of a further growth and reshaping opening the way for fundamental studies of size-dependent scaling laws of optical properties and possible fabrication of nano-reactor or nano-trap patterns.

  9. Argon ion beam induced surface pattern formation on Si

    Energy Technology Data Exchange (ETDEWEB)

    Hofsäss, H.; Bobes, O.; Zhang, K. [2nd Institute of Physics, Faculty of Physics, University Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2016-01-21

    The development of self-organized surface patterns on Si due to noble gas ion irradiation has been studied extensively in the past. In particular, Ar ions are commonly used and the pattern formation was analyzed as function of ion incidence angle, ion fluence, and ion energies between 250 eV and 140 keV. Very few results exist for the energy regime between 1.5 keV and 10 keV and it appears that pattern formation is completely absent for these ion energies. In this work, we present experimental data on pattern formation for Ar ion irradiation between 1 keV and 10 keV and ion incidence angles between 50° and 75°. We confirm the absence of patterns at least for ion fluences up to 10{sup 18} ions/cm{sup 2}. Using the crater function formalism and Monte Carlo simulations, we calculate curvature coefficients of linear continuum models of pattern formation, taking into account contribution due to ion erosion and recoil redistribution. The calculations consider the recently introduced curvature dependence of the erosion crater function as well as the dynamic behavior of the thickness of the ion irradiated layer. Only when taking into account these additional contributions to the linear theory, our simulations clearly show that that pattern formation is strongly suppressed between about 1.5 keV and 10 keV, most pronounced at 3 keV. Furthermore, our simulations are now able to predict whether or not parallel oriented ripple patterns are formed, and in case of ripple formation the corresponding critical angles for the whole experimentally studied energies range between 250 eV and 140 keV.

  10. Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates

    Energy Technology Data Exchange (ETDEWEB)

    Springer, J. [Forschungszentrum Julich GmbH, Julich (Germany). Institute of Photovoltaics; Academy of Sciences of the Czech Republic, Prague (Czech Republic). Institute of Physics; Rech, B.; Reetz, W.; Muller, J. [Forschungszentrum Julich GmbH, Julich (Germany). Institute of Photovoltaics; Vanecek, M. [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Institute of Physics

    2005-01-01

    Influence of front TCO thickness, surface texture and different back reflectors on short-circuit current density and fill factor of thin film silicon solar cells were investigated. For the front TCO studies, we used ZnO layers of different thickness and applied wet chemical etching in diluted HCl. This approach allowed us to adjust ZnO texture and thickness almost independently. Additionally, we used optical modeling to calculate optical absorption losses in every layer. Results show that texture and thickness reduction of front ZnO increase quantum efficiency over the whole spectral range. The major gain is in the red/IR region. However, the higher sheet resistance of the thin ZnO causes a reduction in fill factor. In the back reflector studies, we compared four different back reflectors: ZnO/Ag, Ag, ZnO/Al and Al. ZnO/Ag yielded the best, Al the worst light trapping properties. Furthermore, the Ag back contact turned out to be superior to ZnO/Al for microcrystalline cells. Finally, the smooth ZnO/Ag back contact showed a higher reflectivity than the rough one. We prepared pin cells with rough and smooth ZnO/Ag interface, leaving the roughness of all other interfaces unchanged. (author)

  11. A cytocompatible micro/nano-textured surface with Si-doped titania mesoporous arrays fabricated by a one-step anodization.

    Science.gov (United States)

    Liu, Huibing; Huang, Xiaobo; Yu, Hanwu; Yang, Xiaoning; Zhang, Xiangyu; Hang, Ruiqiang; Tang, Bin

    2017-04-01

    To mimic the hierarchical structure of bone tissues, a hybrid micro/nano-textured titanium surface with Si-doped TiO2 mesoporous arrays is fabricated by a one-step high current anodization (HCA). Specifically, the HCA is carried out in a electrolyte containing NO3(-) and SiO3(2-). The NO3(-) in the electrolyte is demonstrated to play a key role in mediating the formation of honeycombed TiO2 mesoporous arrays, which are different than the nanotubes formed by the mediating of F(-) ion in the conventional anodization. This unique structure endows the coating with improved mechanical properties compared to the nanotube layer. In addition, the Si is incorporated into the coating in a concentration-dependent manner. With the increase of Si doping amount in the coating, both the hydrophilic properties and surface free energy of coatings are obviously enhanced. The cell culture test shows that the osteoblast behaviors on this surface are positively influenced by the doped Si. Therefore, this micro/nano-textured surface coating doped with Si may endow the Ti-based implants long-term stability and good osseointegration.

  12. Mapping Soil Texture of a Plain Area Using Fuzzy-c-Means Clustering Method Based on Land Surface Diurnal Temperature Difference

    Institute of Scientific and Technical Information of China (English)

    WANG De-Cai; ZHANG Gan-Lin; PAN Xian-Zhang; ZHAO Yu-Guo; ZHAO Ming-Song; WANG Gai-Fen

    2012-01-01

    The use of landscape covariates to estimate soil properties is not suitable for the areas of low relief due to the high variability of soil properties in similar topographic and vegetation conditions.A new method was implemented to map regional soil texture (in terms of sand,silt and clay contents) by hypothesizing that the change in the land surface diurnal temperature difference (DTD) is related to soil texture in case of a relatively homogeneous rainfall input.To examine this hypothesis,the DTDs from moderate resolution imagine spectroradiometer (MODIS) during a selected time period,i.e.,after a heavy rainfall between autumn harvest and autumn sowing,were classified using fuzzy-c-means (FCM) clustering.Six classes were generated,and for each class,the sand (> 0.05 mm),silt (0.002-0.05 mm) and clay (< 0.002 mm) contents at the location of maximum membership value were considered as the typical values of that class.A weighted average model was then used to digitally map soil texture.The results showed that the predicted map quite accurately reflected the regional soil variation.A validation dataset produced estimates of error for the predicted maps of sand,silt and clay contents at root mean of squared error values of 8.4%,7.8% and 2.3%,respectively,which is satisfactory in a practical context.This study thus provided a methodology that can help improve the accuracy and efficiency of soil texture mapping in plain areas using easily available data sources.

  13. Quantitative texture-based assessment of one-year changes in fibrotic reticular patterns on HRCT in scleroderma lung disease treated with oral cyclophosphamide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun J.; Brown, Matthew S. [David Geffen School of Medicine, UCLA, Center for Computer Vision and Imaging Biomarker, Department of Radiological Sciences, Los Angeles, CA (United States); Elashoff, Robert [David Geffen School of Medicine, UCLA, Department of Biostatistics and Biomathematics, Los Angeles, CA (United States); Li, Gang [School of Public Health, UCLA, Department of Biostatistics, Los Angeles, CA (United States); Gjertson, David W. [School of Public Health and David Geffen School of Medicine, UCLA, Department of Biostatistics and Pathology, Los Angeles (United States); Lynch, David A. [National Jewish Health, Radiology Department, Denver, CO (United States); Strollo, Diane C. [UPMC Presbyterian, Radiology Department, Pittsburgh, PA (United States); Kleerup, Eric; Tashkin, Donald P. [David Geffen School of Medicine, UCLA, Department of Med-Pul and Critical Care, Los Angeles, CA (United States); Chong, Daniel; Shah, Sumit K.; Ahmad, Shama; Abtin, Fereidoun; Goldin, Jonathan G. [David Geffen School of Medicine, UCLA, Department of Radiological Sciences, Los Angeles, CA (United States)

    2011-12-15

    The Scleroderma Lung Study showed the efficacy of cyclophosphamide in modestly improving the forced vital capacity (FVC) compared with placebo over 1 year. Using changes in texture-based scores that quantify lung fibrosis as the percentage involvement of reticulation patterns, the effectiveness of cyclophosphamide was re-assessed by examining its impact on quantitative lung fibrosis (QLF). Axial HRCT images were acquired (1-mm slice thickness, 10-mm increments) in the prone position at inspiration. A validated model for quantifying interstitial disease patterns was applied to images from 83 subjects at baseline and 12 months. Scores were calculated for six zones (upper, mid, lower of the right/left lung) and the whole lung. Average changes were compared. Correlations were performed between QLF and physiological and clinical scores. From the most severe zones identified at baseline, QLF scores decreased by 2.6% in the cyclophosphamide group, whereas they increased by 9.1% in the placebo group, leading to {proportional_to}12% difference (p = 0.0027). Between-treatment difference in whole lung QLF was {proportional_to}5% (p = 0.0190). Significant associations were observed between changes in QLF and FVC (r = -0.33), dyspnea score (r = -0.29), and consensus visual score (p = 0.0001). QLF scores provide an objective quantitative tool for assessing treatment efficacy in scleroderma-related interstitial lung disease. (orig.)

  14. E-beam-patterned hydrogels to control nanoscale surface bioactivity

    Science.gov (United States)

    Krsko, P.; Saaem, I.; Clancy, R.; Geller, H.; Soteropoulos, P.; Libera, M.

    2005-11-01

    We are interested in controlling the spatial distribution of proteins on surfaces at cellular and subcellular length scales. To do this, we use a variation of e-beam lithography in a field-emission scanning electron microscope (SEM) to radiation crosslink thin films of water- soluble polymers such as poly(ethylene glycol) [PEG] and poly (carboxylic acids). We can simultaneously pattern the resulting hydrogels on silicon or glass surfaces with nanoscale and microscale feature sizes. Using hydroxy-terminated PEG 6800 we create gels with swell ratios between unity and fifteen depending on the degree of radiation crosslinking, and the swelling properties can be interpreted in terms of the Flory-Rehner formulation modified for one-dimensional swelling. While lightly-crosslinked PEG gels resist protein adsorption and cell adhesion as expected, highly crosslinked PEG gels adsorb such proteins as fibronectin and laminin and consequently become adhesive to fibroblasts, macrophages, and neurons. By spatially modulating the degree of crosslinking, we can localize these cells on surfaces and, for example, direct neurite outgrowth. If instead of using hydroxy-terminated PEG we use amine- terminated PEG, we introduce the additional flexibility of creating high-swelling PEG gels that resist nonspecific protein adsorption but to which specific proteins can be covalently bound. These can be surface patterned at submicron spacings, and we can pattern 7500 nanohydrogels in a 100 micron diameter arrays in 10 seconds. This is an areal density ~104 times greater than a modern DNA/protein chip, and the required bioreagents for chip fabrication and processing are proportionately less. We can bind fibronectin and laminin to different arrays, and we show that these proteins maintain their biospecificity after binding to the nanohydrogels with high fidelity. Looking to applications in next-generation protein-chip technology, our most recent experiments compare the performance of nanohydrogel

  15. Laser surface texturing of 316L stainless steel in air and water: A method for increasing hydrophilicity via direct creation of microstructures

    Science.gov (United States)

    Razi, Sepehr; Madanipour, Khosro; Mollabashi, Mahmoud

    2016-06-01

    Laser processing of materials in water contact is sometimes employed for improving the machining, cutting or welding quality. Here, we demonstrate surface patterning of stainless steel grade 316L by nano-second laser processing in air and water. Suitable adjustments of laser parameters offer a variety of surface patterns on the treated targets. Furthermore alterations of different surface features such as surface chemistry and wettability are investigated in various processing circumstances. More than surface morphology, remarkable differences are observed in the surface oxygen content and wettability of the samples treated in air and water at the same laser processing conditions. Mechanisms of the changes are discussed extensively.

  16. How subsurface patterns affect surface energy budget patterns: a sudanian case study

    Science.gov (United States)

    Robert, D.; Cohard, J.; Descloitres, M.; Vandervaere, J.; Braud, I.; Vauclin, M.

    2011-12-01

    Fractured bedrock areas are still challenging for hydrological modeling because of their complex underground property distributions. The heterogeneity in soil hydraulic properties, for example, can control the subsurface water fluxes and create surface soil moisture pattern which becomes preferential areas for runoff production or evapotranspiration. This study aimed to evaluate the impact of a bedrock topography, including outcropping, on subsurface water fluxes and the induced energy budget patterns at the surface. To deal with these ground water/surface water interactions, we run the Parflow-CLM distributed coupled land surface and groundwater model over the 12km2 Ara watershed (Northern Benin) for different bedrock configurations. The Ara catchment is submitted to a sudanian climate with 1200mm total rainfall per year. It is part of the AMMA-Catch project in which 3 meso sites have been documented along a south to north transect in West Africa. The geology of the Ara catchment is composed of metamorphic rocks. The main orientation of the geological structures (and of the gneiss foliation) is roughly north-south and the dip angle is 20° east. These structure create patterns in effective porosity distribution which is supposed to induce subsurface flow perpendicular to surface slope direction. Controlled Parflow-CLM simulation results are compared with energy budget data, including 3 net radiation measurements, eddy covariance station, scintillometric measurements to estimate evapotranspiration at different scales. The experimental device also include ground measurements like distributed surface soil moisture profile and piezometers. Parflow-CLM simulations are in good agreement with energy budget observations if observed Leaf Area Index time series are take into account. Then different hydraulic property distributions (effective porosity, hydraulic transmissivity, water retention curves) are evaluated through watershed dynamic differences.

  17. Contrast-negation and texture synthesis differentially disrupt natural texture appearance

    Directory of Open Access Journals (Sweden)

    Benjamin J Balas

    2012-11-01

    Full Text Available Natural textures have characteristic image statistics that make them discriminable from unnatural textures. For example, both contrast-negation and texture synthesis alter the appearance of natural textures even though each manipulation preserves some features while disrupting others. Here, we examined the extent to which contrast-negation and texture synthesis each introduce or remove critical perceptual features for discriminating unnatural textures from natural textures. We find that both manipulations remove information that observers use for distinguishing natural textures from transformed versions of the same patterns, but do so in different ways. Texture synthesis removes information that is relevant for discrimination in both abstract patterns and ecologically valid textures, and we also observe a category-dependent asymmetry for identifying an oddball real texture among synthetic distractors. Contrast negation exhibits no such asymmetry, and also does not impact discrimination performance in abstract patterns. We discuss our results in the context of the visual system’s tuning to ecologically relevant patterns and other results describing sensitivity to higher-order statistics in texture patterns.

  18. The influence of surface treatment on the implant roughness pattern

    Directory of Open Access Journals (Sweden)

    Marcio Borges Rosa

    2012-10-01

    Full Text Available An important parameter for the clinical success of dental implants is the formation of direct contact between the implant and surrounding bone, whose quality is directly influenced by the implant surface roughness. A screw-shaped design and a surface with an average roughness of Sa of 1-2 µm showed a better result. The combination of blasting and etching has been a commonly used surface treatment technique. The versatility of this type of treatment allows for a wide variation in the procedures in order to obtain the desired roughness. OBJECTIVES: To compare the roughness values and morphological characteristics of 04 brands of implants, using the same type of surface treatment. In addition, to compare the results among brands, in order to assess whether the type of treatment determines the values and the characteristics of implant surface roughness. MATERIAL AND METHODS: Three implants were purchased directly from each selected company in the market, i.e., 03 Brazilian companies (Biomet 3i of Brazil, Neodent and Titaniumfix and 01 Korean company (Oneplant. The quantitative or numerical characterization of the roughness was performed using an interferometer. The qualitative analysis of the surface topography obtained with the treatment was analyzed using scanning electron microscopy images. RESULTS: The evaluated implants showed a significant variation in roughness values: Sa for Oneplant was 1.01 µm; Titaniumfix reached 0.90 µm; implants from Neodent 0.67 µm, and Biomet 3i of Brazil 0.53 µm. Moreover, the SEM images showed very different patterns for the surfaces examined. CONCCLUSIONS: The surface treatment alone is not able to determine the roughness values and characteristics.

  19. 考虑粗糙度影响的表面织构最优参数设计模型%Optimal design model of surface texture with surface roughness considered

    Institute of Scientific and Technical Information of China (English)

    马晨波; 朱华; 孙见君

    2011-01-01

    为考察表面粗糙度对织构表面摩擦学性能的影响,采用求解基于平均雷诺方程的表面织构润滑计算模型的方法,研究综合粗糙度和方向参数等对摩擦系数及最优织构参数的影响规律.结果表明:当织构表面具有横向粗糙条纹时具有较优的摩擦学性能表现;当综合粗糙度σ〈0.5μm时,摩擦系数和最优织构深度不随综合粗糙度的变化而变化,当σ≥0.5μm时,摩擦系数和最优织构深度随粗糙度的增大而增大;最优织构直径随综合粗糙度的增大而增大,最优织构面积比与综合粗糙度之间不相关,最优织构参数不随方向参数的变化而变化.在仿真结果的基础上,建立考虑粗糙度影响时表面织构的最优参数设计模型,试验验证所建立的模型是合理的和正确的.%In order to investigate the frictional performance of textured surfaces when its surface roughness was considered,the influences of composite root-mean-square(RMS) and the orientation parameter on the friction coefficient as well as the optimal parameters of textured surfaces were studied by solving the lubrication computation model of surface texture based on the average Reynolds equation.The results show that: the textured surfaces with the traverse surface roughness have the perfect frictional performance;the friction coefficient and the optimal depth of surface texture increase with the accretion of the composite RMS(σ) when σ0.5 μm,while the friction coefficient and the optimal depth of surface texture do not change with the composite RMS when σ≥0.5 μm;the larger the composite RMS,the larger the optimal diameter of surface texture,the optimal area ratio is not related to the composite RMS,the optimal parameters are not bound up with the orientation parameter.An optimal design model of surface texture is established based on the computational results,and the validation of the model is also verified.

  20. Transient and self-limited nanostructures on patterned surfaces

    Science.gov (United States)

    Dimastrodonato, V.; Pelucchi, E.; Zestanakis, P. A.; Vvedensky, D. D.

    2013-05-01

    Site-controlled quantum dots formed during the deposition of (Al)GaAs layers by metal-organic vapor-phase epitaxy on GaAs(111)B substrates patterned with inverted pyramids result in geometric and compositional self-ordering along the vertical axis of the template. We describe a theoretical scheme that reproduces the experimentally observed time-dependent behavior of this process, including the evolution of the recess and the increase of Ga incorporation along the base of the template to stationary values determined by alloy composition and other growth parameters. Our work clarifies the interplay between kinetics and geometry for the development of self-ordered nanostructures on patterned surfaces, which is essential for the reliable on-demand design of confined systems for applications to quantum optics.

  1. Static contact angle versus volume of distilled water drop on micro patterned surfaces

    OpenAIRE

    Batichsheva Kseniya; Feoktistov Dmitriy; Ovchinikov Vladimir; Misyura Sergey

    2017-01-01

    Static contact angle was determined experimentally in the condition of wetting of polished and laser patterned surfaces of stainless steel substrates by distilled water drops with different volumes. In contrast with polished surface, the contact angle was found to depend on drop volume on micro patterned surfaces. In addition, the enhancement of both hydrophilic and hydrophobic properties was observed on laser patterned surfaces.

  2. Emotional Effects of Dynamic Textures

    Directory of Open Access Journals (Sweden)

    Alexander Toet

    2011-12-01

    Full Text Available This study explores the effects of various spatiotemporal dynamic texture characteristics on human emotions. The emotional experience of auditory (eg, music and haptic repetitive patterns has been studied extensively. In contrast, the emotional experience of visual dynamic textures is still largely unknown, despite their natural ubiquity and increasing use in digital media. Participants watched a set of dynamic textures, representing either water or various different media, and self-reported their emotional experience. Motion complexity was found to have mildly relaxing and nondominant effects. In contrast, motion change complexity was found to be arousing and dominant. The speed of dynamics had arousing, dominant, and unpleasant effects. The amplitude of dynamics was also regarded as unpleasant. The regularity of the dynamics over the textures' area was found to be uninteresting, nondominant, mildly relaxing, and mildly pleasant. The spatial scale of the dynamics had an unpleasant, arousing, and dominant effect, which was larger for textures with diverse content than for water textures. For water textures, the effects of spatial contrast were arousing, dominant, interesting, and mildly unpleasant. None of these effects were observed for textures of diverse content. The current findings are relevant for the design and synthesis of affective multimedia content and for affective scene indexing and retrieval.

  3. Catalytically favorable surface patterns in Pt-Au nanoclusters

    KAUST Repository

    Mokkath, Junais Habeeb

    2013-01-01

    Motivated by recent experimental demonstrations of novel PtAu nanoparticles with highly enhanced catalytic properties, we present a systematic theoretical study that explores principal catalytic indicators as a function of the particle size and composition. We find that Pt electronic states in the vicinity of the Fermi level combined with a modified electron distribution in the nanoparticle due to Pt-to-Au charge transfer are the origin of the outstanding catalytic properties. From our model we deduce the catalytically favorable surface patterns that induce ensemble and ligand effects. © The Royal Society of Chemistry 2013.

  4. Ellipsometry characterization of polycrystalline ZnO layers with the modeling of carrier concentration gradient: Effects of grain boundary, humidity, and surface texture

    Energy Technology Data Exchange (ETDEWEB)

    Sago, Keisuke; Fujiwara, Hiroyuki, E-mail: fujiwara@gifu-u.ac.jp [Center of Innovative Photovoltaic Systems (CIPS), Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan); Kuramochi, Hideto; Iigusa, Hitoshi; Utsumi, Kentaro [Tokyo Research Laboratory, TOSOH Co., Ltd., 2743-1 Hayakawa, Ayase-shi, Kanagawa 252-1123 (Japan)

    2014-04-07

    Spectroscopic ellipsometry (SE) has been applied to study the effects of grain boundary, humidity, and surface texture on the carrier transport properties of Al-doped ZnO layers fabricated by dc and rf magnetron sputtering. In the SE analysis, the variation in the free carrier absorption toward the growth direction, induced by the ZnO grain growth on foreign substrates, has been modeled explicitly by adopting a multilayer model in which the optical carrier concentration (N{sub opt}) varies continuously with a constant optical mobility (μ{sub opt}). The effect of the grain boundary has been studied by comparing μ{sub opt} with Hall mobility (μ{sub Hall}). The change in μ{sub Hall}/μ{sub opt} indicates a sharp structural transition of the ZnO polycrystalline layer at a thickness of d ∼ 500 nm, which correlates very well with the structure confirmed by transmission electron microscopy. In particular, below the transition thickness, the formation of the high density grain boundary leads to the reduction in the μ{sub Hall}/μ{sub opt} ratio as well as N{sub opt}. As a result, we find that the thickness dependence of the carrier transport properties is almost completely governed by the grain boundary formation. On the other hand, when the ZnO layer is exposed to wet air at 85 °C, μ{sub Hall} reduces drastically with a minor variation of μ{sub opt} due to the enhanced grain boundary scattering. We have also characterized textured ZnO:Al layers prepared by HCl wet etching by SE. The analysis revealed that the near-surface carrier concentration increases slightly after the etching. We demonstrate that the SE technique can be applied to distinguish various rough textured structures (size ∼ 1 μm) of the ZnO layers prepared by the HCl etching.

  5. Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption.

    Science.gov (United States)

    Giannakoudakis, Dimitrios; Saroyan, Hayarpi; Lazaridis, Nikolaos; Deliyanni, Eleni

    2016-04-01

    Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption. Dimitrios Giannakoudakis1, Hayarpi Saroyan2, Nikolaos Lazaridis2, Eleni Deliyanni2 1 City College of New York, Chemistry Department, 160 Convent Avenue, New York, United States 2 Laboratory of General and oInorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece In this study, the effect of preparation route of a mesoporous magnetic activated carbon on Reactive Black 5 (RB5) adsorption was investigated. The synthesis of the magnetic activated carbon was achieved both with (i) impregnation method (Bmi), and (ii) co-precipitation with two precipitation agents: NaOH (Bm) and NH4OH (Bma). After synthesis, the full characterization with various techniques (SEM, FTIR, XRD, DTA, DTG, VSM) was achieved in order to testify the effect of the preparation route on its textural and surface properties. It was shown that after the precipitation method the prepared carbon presented a collapsed texture and small magnetic properties. Effects of initial solution pH, effect of temperature, adsorption isotherms and kinetics were investigated in order to conclude about the aforementioned effect of the preparation method on dye adsorption performance of the magnetic carbons. The adsorption evaluation of the magnetic activated carbon presented higher adsorption capacity of Bmi carbon (350 mg/g) and lower of Bm (150 mg/g). Equilibrium experiments are also performed studying the effect of contact time (pseudo-first and -second order equations) and temperature (isotherms at 25, 45 and 65 °C fitted to Langmuir and Freundlich model). A full thermodynamic evaluation was carried out, calculating the parameters of enthalpy, free energy and entropy (ΔHο, ΔGο and ΔSο). The characterization with various techniques revealed the possible interactions/forces of dye-composite system.

  6. Curvature-induced symmetry breaking determines elastic surface patterns

    Science.gov (United States)

    Stoop, Norbert; Lagrange, Romain; Terwagne, Denis; Reis, Pedro M.; Dunkel, Jörn

    2015-03-01

    Symmetry-breaking transitions associated with the buckling and folding of curved multilayered surfaces—which are common to a wide range of systems and processes such as embryogenesis, tissue differentiation and structure formation in heterogeneous thin films or on planetary surfaces—have been characterized experimentally. Yet owing to the nonlinearity of the underlying stretching and bending forces, the transitions cannot be reliably predicted by current theoretical models. Here, we report a generalized Swift-Hohenberg theory that describes wrinkling morphology and pattern selection in curved elastic bilayer materials. By testing the theory against experiments on spherically shaped surfaces, we find quantitative agreement with analytical predictions for the critical curves separating labyrinth, hybrid and hexagonal phases. Furthermore, a comparison to earlier experiments suggests that the theory is universally applicable to macroscopic and microscopic systems. Our approach builds on general differential-geometry principles and can thus be extended to arbitrarily shaped surfaces.

  7. Human epididymis: structural pattern, total length and inner surface area.

    Science.gov (United States)

    Skandhan, Kalanghot P; Soni, Ashutosh; Joshi, Anantkumar; Avni, Kalanghot P S; Gupta, Bansi Dhar

    2017-05-24

    The organ epididymis is secured the name considering it functioned as an appendix to the testis; earlier testis was called as didymi. Regarding the length of human epididymis, several values are attributed by different authors. The present study was aimed to find out the pattern, total length and inner surface area of human epididymis. The study was conducted by employing microsurgical procedures on five testes from unclaimed human dead bodies. Caput was formed by few tubes interconnecting at three levels. These tubes led to corpus, which in turn was having more number of tubes interconnecting at different levels. Tubules were many looking like a mesh. United tubes of corpus form the single tube to form cauda. Epididymis length was 30.48 cm. Inner surface area was 818.16 mm2. Reported values of others seem to be a modified version from that of animals. Authors believe that organic revolutionary changes in man led to a reduction in the length of epididymis.

  8. Wetting of two-dimensional physically patterned surfaces

    Science.gov (United States)

    Bell, Michael Scott

    An understanding of wetting phenomena is important, in part, due to the many practical applications of controlled wetting. Some of the most exciting applications involve superhydrophobic surfaces, on which water droplets exhibit contact angles larger than 150° and contact angle hysteresis less than 10°. These surfaces are notable for their low-drag, antifouling, and self-cleaning properties, among others. Wetting is known to be affected by both the chemistry and the physical patterning of a surface, with the chemistry affecting what is called the intrinsic contact angle, which is the contact angle displayed by a droplet on a smooth flat surface made of the given material. To date, the largest intrinsic contact angle observed for any material is only about 120°, which does not confer superhydrophobicity. Thus, physical patterning is a crucial component of any superhydrophobic surface. Interestingly, many natural examples of superhydrophobic surfaces exist, with one of the most notable being the lotus leaf. In designing such surfaces, scientists have turned to the natural examples for inspiration, and have found that most natural examples have multiple (usually two) scales of roughness, commonly referred to as hierarchical roughness. Though hierarchical roughness is ubiquitous in the superhydrophobic surfaces of the natural world, its precise role in conferring superhydrophobicity has so far remained elusive. In this work, we develop a thermodynamic model to study the wetting of two-dimensional physically patterned surfaces. Past models that have been developed for this purpose often make several assumptions: the drop must be much larger than the surface features while simultaneously being small enough that the effects of gravity are negligible. Many of these models ultimately rely on the older Cassie and Wenzel models, which themselves make assumptions about the drop size relative to the surface features--namely that the drop is again much larger than the surface

  9. Analytic methods for predicting biosettlement on patterned surfaces

    Science.gov (United States)

    Long, Christopher James

    Marine organism fouling of surfaces has significant impact on our environment and the economy. Increased fuel use due to drag costs approximately $600 million annually in the United States alone. The efficiency of marine vessels substantially decreases due to fouling. Toxins in some antifouling paints accumulate in the marine environment and produce negative effects on the marine ecology. There is a critical need for effective non-toxic, anti-fouling, marine coatings that reduce operational costs and the overall environmental impact of ocean vessels on the environment. Our approach is to investigate the interaction between the wettability of surfaces with the response of fouling organisms. One of the ways the wettability can be influenced is through the use of topography. Since the topographies have directionality, the direction dependence of the wettability was determined on several microscale topographies that have previously shown antifouling potential. Breaking microscale ridges into the discontinuous features in the antifouling topographies reduced the anisotropies in the contact angles, but did not eliminate anisotropy. The number of distinct features in the design and the area fraction of the topographic features were found to influence settlement of the fouling alga Ulva linza. A biosettlement model, refined from previous work, predicts the settlement of Ulva linza to three previously untested surfaces. These surfaces significantly reduced the settlement of these spores in vitro by up to 78%. The attachment of another species of fouler, the diatom Navicula perminuta, was reduced by approximately 35% on several surfaces that reduced Ulva linza settlement. The Navicula cells responded differently to the topographies than the Ulva linza spores. A mapping technique was developed to determine the two-dimensional settlement pattern of cells on the topographical surfaces. This technique revealed and quantified several preferential locations for Ulva linza

  10. Liquid jet impinging orthogonally on a wettability-patterned surface

    Science.gov (United States)

    Koukoravas, Theodore; Ghosh, Aritra; Sinha Mahapatra, Pallab; Ganguly, Ranjan; Megaridis, Constantine

    2016-11-01

    Jet impingement has many technological applications because of its numerous merits, especially those related to the ability of liquids to carry away heat very efficiently. The present study introduces a new configuration employing a wettability-patterning approach to divert an orthogonally-impinging laminar water jet onto a predetermined portion of the target surface. Diverging wettable tracks on a superhydrophobic background provide the means to re-direct the impinging jet along paths determined by the shape of these tracks on the solid surface. In a heat transfer example of this method, an open-surface heat exchanger is constructed and its heat transfer performance is characterized. Since this approach facilitates prolonged liquid contact with the underlying heated surface through thin-film spreading, evaporative cooling is also promoted. We demonstrate flow cases extracting 100 W/cm2 at water flow rates of O(10 mL/min). By comparing with other jet-impingement cooling approaches, the present method provides roughly four times more efficient cooling by using less amount of coolant. The reduced coolant use, combined with the gravity-independent character of this technique, offer a new paradigm for compact heat transfer devices designed to operate in reduced- or zero-gravity environments.

  11. Liquid Droplet Impact Dynamics on Micro-Patterned Superhydrophobic Surfaces

    CERN Document Server

    Clavijo, Cristian; Crockett, Julie

    2013-01-01

    The video exhibits experimental qualitative and quantitative results of water/glycerol (50%/50% by mass) droplet impact on two types of micro-patterned superhydrophobic surfaces. The two types of surfaces used were 80% cavity fraction ribs and posts with a periodic spacing of 40 {\\mu}m and 32 {\\mu}m, respectively. All surfaces were manufactured through photolithography. The impact Weber number is used as the dynamic parameter to compare splash and rebound behaviors between the two types of surfaces. While droplets exhibit similar dynamics at low Weber numbers, rebound jet speed (normalized by droplet impact speed) is notably higher on posts than ribs for all Weber numbers tested here (5 265. On posts, satellite droplets also follow a specific path but in a different orientation. Satellite droplets form in locations aligned with the post lattice structure. This behavior is observed for 600 < We < 750. Jet rebound exhibits an interesting phenomenon on ribs under certain conditions. Due to the uneven shear...

  12. A texture based pattern recognition approach to distinguish melanoma from non-melanoma cells in histopathological tissue microarray sections.

    Directory of Open Access Journals (Sweden)

    Elton Rexhepaj

    Full Text Available AIMS: Immunohistochemistry is a routine practice in clinical cancer diagnostics and also an established technology for tissue-based research regarding biomarker discovery efforts. Tedious manual assessment of immunohistochemically stained tissue needs to be fully automated to take full advantage of the potential for high throughput analyses enabled by tissue microarrays and digital pathology. Such automated tools also need to be reproducible for different experimental conditions and biomarker targets. In this study we present a novel supervised melanoma specific pattern recognition approach that is fully automated and quantitative. METHODS AND RESULTS: Melanoma samples were immunostained for the melanocyte specific target, Melan-A. Images representing immunostained melanoma tissue were then digitally processed to segment regions of interest, highlighting Melan-A positive and negative areas. Color deconvolution was applied to each region of interest to separate the channel containing the immunohistochemistry signal from the hematoxylin counterstaining channel. A support vector machine melanoma classification model was learned from a discovery melanoma patient cohort (n = 264 and subsequently validated on an independent cohort of melanoma patient tissue sample images (n = 157. CONCLUSION: Here we propose a novel method that takes advantage of utilizing an immuhistochemical marker highlighting melanocytes to fully automate the learning of a general melanoma cell classification model. The presented method can be applied on any protein of interest and thus provides a tool for quantification of immunohistochemistry-based protein expression in melanoma.

  13. Generation of Focused Electric Field Patterns at Dielectric Surfaces

    Science.gov (United States)

    Olofsson, Jessica; Levin, Mikael; Strömberg, Anette; Weber, Stephen G.; Ryttsén, Frida; Orwar, Owe

    2006-01-01

    We here report on a concept for creating well-defined electric field gradients between the boundaries of capillary electrode (a capillary of a nonconducting material equipped with an interior metal electrode) outlets, and dielectric surfaces. By keeping a capillary electrode opening close to a boundary between a conducting solution and a nonconducting medium, a high electric field can be created close to the interface by field focusing effects. By varying the inner and outer diameters of the capillary, the span of electric field strengths and the field gradient obtained can be controlled, and by varying the slit height between the capillary rim and the surface, or the applied current, the average field strength and gradient can be varied. Field focusing effects and generation of electric field patterns were analyzed using finite element method simulations. We experimentally verified the method by electroporation of a fluorescent dye (fluorescein diphosphate) into adherent, monolayered cells (PC-12 and WSS-1) and obtained a pattern of fluorescent cells corresponding to the focused electric field. PMID:16013887

  14. Quantitative Morphologic Analysis of Boulder Shape and Surface Texture to Infer Environmental History: A Case Study of Rock Breakdown at the Ephrata Fan, Channeled Scabland, Washington

    Science.gov (United States)

    Ehlmann, Bethany L.; Viles, Heather A.; Bourke, Mary C.

    2008-01-01

    Boulder morphology reflects both lithology and climate and is dictated by the combined effects of erosion, transport, and weathering. At present, morphologic information at the boulder scale is underutilized as a recorder of environmental processes, partly because of the lack of a systematic quantitative parameter set for reporting and comparing data sets. We develop such a parameter set, incorporating a range of measures of boulder form and surface texture. We use standard shape metrics measured in the field and fractal and morphometric classification methods borrowed from landscape analysis and applied to laser-scanned molds. The parameter set was pilot tested on three populations of basalt boulders with distinct breakdown histories in the Channeled Scabland, Washington: (1) basalt outcrop talus; (2) flood-transported boulders recently excavated from a quarry; and (3) flood-transported boulders, extensively weathered in situ on the Ephrata Fan surface. Size and shape data were found to distinguish between flood-transported and untransported boulders. Size and edge angles (approximately 120 degrees) of flood-transported boulders suggest removal by preferential fracturing along preexisting columnar joints, and curvature data indicate rounding relative to outcrop boulders. Surface textural data show that boulders which have been exposed at the surface are significantly rougher than those buried by fan sediments. Past signatures diagnostic of flood transport still persist on surface boulders, despite ongoing overprinting by processes in the present breakdown environment through roughening and fracturing in situ. Further use of this quantitative boulder parameter set at other terrestrial and planetary sites will aid in cataloging and understanding morphologic signatures of environmental processes.

  15. Quantitative Morphologic Analysis of Boulder Shape and Surface Texture to Infer Environmental History: A Case Study of Rock Breakdown at the Ephrata Fan, Channeled Scabland, Washington

    Science.gov (United States)

    Ehlmann, Bethany L.; Viles, Heather A.; Bourke, Mary C.

    2008-01-01

    Boulder morphology reflects both lithology and climate and is dictated by the combined effects of erosion, transport, and weathering. At present, morphologic information at the boulder scale is underutilized as a recorder of environmental processes, partly because of the lack of a systematic quantitative parameter set for reporting and comparing data sets. We develop such a parameter set, incorporating a range of measures of boulder form and surface texture. We use standard shape metrics measured in the field and fractal and morphometric classification methods borrowed from landscape analysis and applied to laser-scanned molds. The parameter set was pilot tested on three populations of basalt boulders with distinct breakdown histories in the Channeled Scabland, Washington: (1) basalt outcrop talus; (2) flood-transported boulders recently excavated from a quarry; and (3) flood-transported boulders, extensively weathered in situ on the Ephrata Fan surface. Size and shape data were found to distinguish between flood-transported and untransported boulders. Size and edge angles (approximately 120 degrees) of flood-transported boulders suggest removal by preferential fracturing along preexisting columnar joints, and curvature data indicate rounding relative to outcrop boulders. Surface textural data show that boulders which have been exposed at the surface are significantly rougher than those buried by fan sediments. Past signatures diagnostic of flood transport still persist on surface boulders, despite ongoing overprinting by processes in the present breakdown environment through roughening and fracturing in situ. Further use of this quantitative boulder parameter set at other terrestrial and planetary sites will aid in cataloging and understanding morphologic signatures of environmental processes.

  16. Improved bioactivity of selective laser melting titanium: Surface modification with micro-/nano-textured hierarchical topography and bone regeneration performance evaluation.

    Science.gov (United States)

    Xu, Jia-Yun; Chen, Xian-Shuai; Zhang, Chun-Yu; Liu, Yun; Wang, Jing; Deng, Fei-Long

    2016-11-01

    Selective laser melting (SLM) titanium requires surface modification to improve its bioactivity. The microrough surface of it can be utilized as the micro primary substrate to create a micro-/nano-textured topography for improved bone regeneration. In this study, the microrough SLM titanium substrate was optimized by sandblasting, and nano-porous features of orderly arranged nanotubes and disorderly arranged nanonet were produced by anodization (SAN) and alkali-heat treatment (SAH), respectively. The results were compared with the control group of an untreated surface (native-SLM) and a microtopography only surface treated by acid etching (SLA). The effects of the different topographies on cell functions and bone formation performance were evaluated in vitro and in vivo. It was found that micro-/nano-textured topographies of SAN and SAH showed enhanced cell behaviour relative to the microtopography of SLA with significantly higher proliferation on the 1st, 3rd, 5th and 7th day (P<0.05) and higher total protein contents on the 14th day (P<0.05). In vivo, SAN and SAH formed more successively regenerated bone, which resulted in higher bone-implant contact (BIC%) and bone-bonding force than native-SLM and SLA. In addition, the three-dimensional nanonet of SAH was expected to be more similar to native extracellular matrix (ECM) and thus led to better bone formation. The alkaline phosphatase activity of SAH was significantly higher than the other three groups at an earlier stage of the 7th day (P<0.05) and the BIC% was nearly double that of native-SLM and SLA in the 8th week. In conclusion, the addition of nano-porous features on the microrough SLM titanium surface is effective in improving the bioactivity and bone regeneration performance, in which the ECM-like nanonet with a disorderly arranged biomimetic feature is suggested to be more efficient than nanotubes.

  17. Magnetic texture of Nd2Fe14B solidified in the surface layer of anisotropic sintered-magnets

    Institute of Scientific and Technical Information of China (English)

    PAN Jing; LIU Xincai; TU Fenghua

    2006-01-01

    The arrangements of the easy magnetization axis [001] of columnar Nd2Fe14B crystals in the laser scanned layer on anisotropic sintered Nd15Fe77B8 magnets were investigated by XRD and the Bitter method. The results show that the common effects of both the heat flux and the substrate magnetization orientation constrain the columnar Nd2Fe14B solidified from the laser melting pool to form the c -axis texture orientated with the same direction as that of the substrate, when the geometric relationship between the heat flux in the laser scanning layer and c -axis texture orientation of the substrate is perpendicular to each other, and if the laser scanning velocity is no less than 25 mm·min-1 . The c -axes of columnar Nd2Fe14B crystals are no longer randomly distributed in the plane normal to their preferential growing direction as they are randomly done in both ingots cooled by water-cooling copper mould and directionally solidified Nd-Fe-B rods.

  18. Influence of texture coefficient on surface morphology and sensing properties of W-doped nanocrystalline tin oxide thin films.

    Science.gov (United States)

    Kumar, Manjeet; Kumar, Akshay; Abhyankar, A C

    2015-02-18

    For the first time, a new facile approach based on simple and inexpensive chemical spray pyrolysis (CSP) technique is used to deposit Tungsten (W) doped nanocrystalline SnO2 thin films. The textural, optical, structural and sensing properties are investigated by GAXRD, UV spectroscopy, FESEM, AFM, and home-built sensing setup. The gas sensing results indicate that, as compared to pure SnO2, 1 wt % W-doping improves sensitivity along with better response (gas at operating temperatures of ∼225 °C. The optimal composition of 1 wt % W-doped films exhibit lowest crystallite size of the order of ∼8-10 nm with reduced energy band gap and large roughness values of 3.82 eV and 3.01 nm, respectively. Reduction in texture coefficient along highly dense (110) planes with concomitant increase along loosely packed (200) planes is found to have prominent effect on gas sensing properties of W-doped films.

  19. Enhancement of silicon using micro-patterned surfaces of thin films

    Directory of Open Access Journals (Sweden)

    E Kaivosoja

    2010-04-01

    Full Text Available Micro-textured biomaterials might enhance cytocompatibility of silicon-based micro-electro-mechanical system (bio-MEMS dummies. Photolithography-physical vapour deposition was used to produce diamond-like carbon (DLC or Ti squares and circles on silicon, and also their inverse replicas; then DLC and Ti were compared for their guiding potential, using a SaOS-2 cell model. Scanning electron microscopy at 48 hours indicated cells were well-spread on large-sized patterns (several cells on one pattern and assumed the geometrical architecture of underlying features. Medium-sized patterns (slightly smaller than solitary indicator cells were inhabited by singular cells, which stretched from one island to another, assuming longitudinal or branching morphologies. On small-sized patterns (much smaller than individual cells cells covered large micro-textured areas, but cellular filopodia bypassed the bare silicon. Immunofluorescence and confocal laser scanning microscopy indicated that the actin cytoskeleton and vinculin-containing adhesion junctions were present on the patterned areas, but not on the bare silicon. Cell density/coverage disclosed a 3.4-3.7-fold preference for the biomaterial patterns over silicon substrate (p < 0.001. Differences in the cellular response between materials were lost at 120 hours when cells were confluent. The working hypothesis was proven; enhancement by micro-patterning depends on the pattern size, shape and material and can be used to improve biocompatibility during the initial integration phase of the device.

  20. Focal Conic Flower Textures at Curved Interfaces

    Directory of Open Access Journals (Sweden)

    Daniel A. Beller

    2013-12-01

    Full Text Available Focal conic domains (FCDs in smectic-A liquid crystals have drawn much attention, both for their exquisitely structured internal form and for their ability to direct the assembly of micromaterials and nanomaterials in a variety of patterns. A key to directing FCD assembly is control over the eccentricity of the domain. Here, we demonstrate a new paradigm for creating spatially varying FCD eccentricity by confining a hybrid-aligned smectic with curved interfaces. In particular, we manipulate interface behavior with colloidal particles in order to experimentally produce two examples of what has recently been dubbed the flower texture [C. Meyer et al., Focal Conic Stacking in Smectic A Liquid Crystals: Smectic Flower and Apollonius Tiling, Materials 2, 499, 2009MATEG91996-194410.3390/ma2020499], where the focal hyperbolæ diverge radially outward from the center of the texture, rather than inward as in the canonical éventail or fan texture. We explain how this unconventional assembly can arise from appropriately curved interfaces. Finally, we present a model for this system that applies the law of corresponding cones, showing how FCDs may be embedded smoothly within a “background texture” of large FCDs and concentric spherical layers, in a manner consistent with the qualitative features of the smectic flower. Such understanding could potentially lead to disruptive liquid-crystal technologies beyond displays, including patterning, smart surfaces, microlens arrays, sensors, and nanomanufacturing.

  1. Laser interference patterning methods: Possibilities for high-throughput fabrication of periodic surface patterns

    Science.gov (United States)

    Lasagni, Andrés Fabián

    2017-06-01

    Fabrication of two- and three-dimensional (2D and 3D) structures in the micro- and nano-range allows a new degree of freedom to the design of materials by tailoring desired material properties and, thus, obtaining a superior functionality. Such complex designs are only possible using novel fabrication techniques with high resolution, even in the nanoscale range. Starting from a simple concept, transferring the shape of an interference pattern directly to the surface of a material, laser interferometric processing methods have been continuously developed. These methods enable the fabrication of repetitive periodic arrays and microstructures by irradiation of the sample surface with coherent beams of light. This article describes the capabilities of laser interference lithographic methods for the treatment of both photoresists and solid materials. Theoretical calculations are used to calculate the intensity distributions of patterns that can be realized by changing the number of interfering laser beams, their polarization, intensity and phase. Finally, different processing systems and configurations are described and, thus, demonstrating the possibility for the fast and precise tailoring of material surface microstructures and topographies on industrial relevant scales as well as several application cases for both methods.

  2. Plasma assisted nitriding for micro-texturing onto martensitic stainless steels*

    Directory of Open Access Journals (Sweden)

    Katoh Takahisa

    2015-01-01

    Full Text Available Micro-texturing method has grown up to be one of the most promising procedures to form micro-lines, micro-dots and micro-grooves onto the mold-die materials and to duplicate these micro-patterns onto metallic or polymer sheets via stamping or injection molding. This related application requires for large-area, fine micro-texturing onto the martensitic stainless steel mold-die materials. A new method other than laser-machining, micro-milling or micro-EDM is awaited for further advancement of this micro-texturing. In the present paper, a new micro-texturing method is developed on the basis of the plasma assisted nitriding to transform the two-dimensionally designed micro-patterns to the three dimensional micro-textures in the martensitic stainless steels. First, original patterns are printed onto the surface of stainless steel molds by using the dispenser or the ink-jet printer. Then, the masked mold is subjected to high density plasma nitriding; the un-masked surfaces are nitrided to have higher hardness, 1400 Hv than the matrix hardness, 200 Hv of stainless steels. This nitrided mold is further treated by sand-blasting to selectively remove the soft, masked surfaces. Finally, the micro-patterned martensitic stainless steel mold is fabricated as a tool to duplicate these micro-patterns onto the plastic materials by the injection molding.

  3. Fabrication of sub-micron surface structures on copper, stainless steel and titanium using picosecond laser interference patterning

    Energy Technology Data Exchange (ETDEWEB)

    Bieda, Matthias, E-mail: matthias.bieda@iws.fraunhofer.de [Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, 01277 Dresden (Germany); Siebold, Mathias, E-mail: m.siebold@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Lasagni, Andrés Fabián, E-mail: andres_fabian.lasagni@tu-dresden.de [Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, 01277 Dresden (Germany); Technische Universität Dresden, Institut für Fertigungstechnik, 01062 Dresden (Germany)

    2016-11-30

    Highlights: • Laser interference patterning is introduced to generate sub-micrometer surface pattern. • The two-temperature model is applied to ps-laser interference patterning of metals. • Line-like structures with a pitch of 0.7 μm were fabricated on SAE 304, Ti and Cu. • The process is governed by a photo-thermal mechanism for a pulse duration of 35 ps. • A “cold”-ablation process for metals requires a pulse duration shorter than 10 ps. - Abstract: Picosecond direct laser interference patterning (ps-DLIP) is investigated theoretically and experimentally for the bulk metals copper, stainless steel and titanium. While surface texturing with nanosecond pulses is limited to feature sizes in the micrometer range, utilizing picosecond pulses can lead to sub-micrometer structures. The modelling and simulation of ps-DLIP are based on the two-temperature model and were carried out for a pulse duration of 35 ps at 515 nm wavelength and a laser fluence of 0.1 J/cm{sup 2}. The subsurface temperature distribution of both electrons and phonons was computed for periodic line-like structures with a pitch of 0.8 μm. The increase in temperature rises for a lower absorption coefficient and a higher thermal conductivity. The distance, at which the maximum subsurface temperature occurs, increases for a small absorption coefficient. High absorption and low thermal conductivity minimize internal heating and give rise to a pronounced surface micro topography with pitches smaller than 1 μm. In order to confirm the computed results, periodic line-like surface structures were produced using two interfering beams of a Yb:YAG-Laser with 515 nm wavelength and a pulse duration of 35 ps. It was possible to obtain a pitch of 0.7 μm on the metallic surfaces.

  4. Methods for analyzing surface texture effects of volcanoes with Plinian and subplinian eruptions types: Cases of study Lascar (23 S) and Chaiten (42 S), Chile

    CERN Document Server

    Fernandez, L; Salinas, R

    2016-01-01

    This paper presents a new methodology that provides the analysis of surface texture changes in areas adjacent to the volcano and its impact product of volcanic activity. To do this, algorithms from digital image processing such as the co-occurrence matrix and the wavelet transform are used. These methods are working on images taken by the Landsat satellite platform sensor 5 TM and Landsat 7 ETM + sensor, and implemented with the purpose of evaluating superficial changes that can warn of surface movements of the volcano. The results were evaluated by similarity metrics for grayscale images, and validated in two different scenarios that have the same type of eruption, but differ, essentially, in climate and vegetation. Finally, the proposed algorithm is presented, setting the parameters and constraints for implementation and use.

  5. Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Satoshi

    2012-11-01

    This work addresses the metal nanocluster growth process on prepatterned substrates, the development of atomistic simulation method with respect to an acceleration of the atomistic transition states, and the continuum model of the ion-beam inducing semiconductor surface pattern formation mechanism. Experimentally, highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO{sub 2} surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well-separated. The first topic is the investigation of this growth process with a continuum theoretical approach to the surface gas condensation as well as an atomistic cluster growth model. The atomistic simulation model is a lattice-based kinetic Monte-Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag monomers and {approx}1 nm square surface migration ranges of Ag monomers. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. The second topic specifies the acceleration scheme utilized in the metallic cluster growth model. Concerning the atomistic movements, a classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements

  6. Effect of Vegetation Patterns on SAR derived Surface Soil Moisture Distribution

    Science.gov (United States)

    Koyama, C. N.; Schneider, K.

    2012-12-01

    Soil moisture can be regarded as one of the important life sustaining entities on our planet. Among its various functions, the first is probably to enable the growth of vegetation on the land surface. Apart from this, water stored in soils plays many other important roles in the global water (and energy) cycle. In the past decades, radar imaging has proven its potential to quantitatively estimate the near surface water content of soils at high spatial resolutions. The use of active microwave data to measure surface soil moisture requires the consideration of several factors like e.g. soil texture, surface roughness, and vegetation. Among these factors, the presence of a vegetation cover is perhaps the major impediment to accurate quantitative retrievals of soil moisture. On the one hand, the vegetation has a disturbing effect on the radar reflectivity and thus causes errors in the soil moisture retrieval which is generally based on theoretical or experimental relationships between the dielectric properties of the soil surface and the radar backscattering coefficient. On the other hand, the spatial distribution of vegetation with e.g. different crop types with different transpiration coefficients and different phenological development, etc, can cause large variations in the plant water consumption and thus has a significant impact on the soil moisture patterns. We have developed methods to estimate the amount of biomass for different crop types and the underlying surface soil water content directly from polarimetric L-band SAR images. While the horizontally-transmit horizontally-receive co-polarization (hh) is most sensitive towards the dielectric soil properties, the horizontally-transmit vertically-receive cross-polarization (hv) is much more sensitive towards the backscattering from the vegetation canopy. In addition the polarimetric observables entropy (H), alpha angle (α), and the total reflected power (span), all of which are highly affected by the canopy

  7. Hydrodynamic approach to surface pattern formation by ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Mario, E-mail: marioc@upcomillas.es [Grupo Interdisciplinar de Sistemas Complejos (GISC) and Grupo de Dinamica No Lineal (DNL), Escuela Tecnica Superior de Ingenieri a - ICAI, Universidad Pontificia Comillas, E-28015 Madrid (Spain); Cuerno, Rodolfo [Departamento de Matematicas and GISC, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganes (Spain)

    2012-02-15

    On the proper timescale, amorphous solids can flow. Solid flow can be observed macroscopically in glaciers or lead pipes, but it can also be artificially enhanced by creating defects. Ion Beam Sputtering (IBS) is a technique in which ions with energies in the 0.110 keV range impact against a solid target inducing defect creation and dynamics, and eroding its surface leading to formation of ordered nanostructures. Despite its technological interest, a basic understanding of nanopattern formation processes occurring under IBS of amorphizable targets has not been clearly established, recent experiments on Si having largely questioned knowledge accumulated during the last two decades. A number of interfacial equations have been proposed in the past to describe these phenomena, typically by adding together different contributions coming from surface diffusion, ion sputtering or mass redistribution, etc. in a non-systematic way. Here, we exploit the general idea of solids flowing due to ion impacts in order to establish a general framework into which different mechanisms (such as viscous flow, stress, diffusion, or sputtering) can be incorporated, under generic physical conservation laws. As opposed to formulating phenomenological interfacial equations, this approach allows to assess systematically the relevance and interplay of different physical mechanisms influencing surface pattern formation by IBS.

  8. Integration of plasma-assisted surface chemical modification, soft lithography, and protein surface activation for single-cell patterning

    Science.gov (United States)

    Cheng, Q.; Komvopoulos, K.

    2010-07-01

    Surface patterning for single-cell culture was accomplished by combining plasma-assisted surface chemical modification, soft lithography, and protein-induced surface activation. Hydrophilic patterns were produced on Parylene C films deposited on glass substrates by oxygen plasma treatment through the windows of polydimethylsiloxane shadow masks. After incubation first with Pluronic F108 solution and then serum medium overnight, surface seeding with mesenchymal stem cells in serum medium resulted in single-cell patterning. The present method provides a means of surface patterning with direct implications in single-cell culture.

  9. Combination of 3D skin surface texture features and 2D ABCD features for improved melanoma diagnosis.

    Science.gov (United States)

    Ding, Yi; John, Nigel W; Smith, Lyndon; Sun, Jiuai; Smith, Melvyn

    2015-10-01

    Two-dimensional asymmetry, border irregularity, colour variegation and diameter (ABCD) features are important indicators currently used for computer-assisted diagnosis of malignant melanoma (MM); however, they often prove to be insufficient to make a convincing diagnosis. Previous work has demonstrated that 3D skin surface normal features in the form of tilt and slant pattern disruptions are promising new features independent from the existing 2D ABCD features. This work investigates that whether improved lesion classification can be achieved by combining the 3D features with the 2D ABCD features. Experiments using a nonlinear support vector machine classifier show that many combinations of the 2D ABCD features and the 3D features can give substantially better classification accuracy than using (1) single features and (2) many combinations of the 2D ABCD features. The best 2D and 3D feature combination includes the overall 3D skin surface disruption, the asymmetry and all the three colour channel features. It gives an overall 87.8 % successful classification, which is better than the best single feature with 78.0 % and the best 2D feature combination with 83.1 %. These demonstrate that (1) the 3D features have additive values to improve the existing lesion classification and (2) combining the 3D feature with all the 2D features does not lead to the best lesion classification. The two ABCD features not selected by the best 2D and 3D combination, namely (1) the border feature and (2) the diameter feature, were also studied in separate experiments. It found that inclusion of either feature in the 2D and 3D combination can successfully classify 3 out of 4 lesion groups. The only one group not accurately classified by either feature can be classified satisfactorily by the other. In both cases, they have shown better classification performances than those without the 3D feature in the combinations. This further demonstrates that (1) the 3D feature can be used to

  10. Depth image enhancement using perceptual texture priors

    Science.gov (United States)

    Bang, Duhyeon; Shim, Hyunjung

    2015-03-01

    A depth camera is widely used in various applications because it provides a depth image of the scene in real time. However, due to the limited power consumption, the depth camera presents severe noises, incapable of providing the high quality 3D data. Although the smoothness prior is often employed to subside the depth noise, it discards the geometric details so to degrade the distance resolution and hinder achieving the realism in 3D contents. In this paper, we propose a perceptual-based depth image enhancement technique that automatically recovers the depth details of various textures, using a statistical framework inspired by human mechanism of perceiving surface details by texture priors. We construct the database composed of the high quality normals. Based on the recent studies in human visual perception (HVP), we select the pattern density as a primary feature to classify textures. Upon the classification results, we match and substitute the noisy input normals with high quality normals in the database. As a result, our method provides the high quality depth image preserving the surface details. We expect that our work is effective to enhance the details of depth image from 3D sensors and to provide a high-fidelity virtual reality experience.

  11. Guiding catalytically active particles with chemically patterned surfaces

    CERN Document Server

    Uspal, W E; Dietrich, S; Tasinkevych, M

    2016-01-01

    Catalytically active Janus particles suspended in solution create gradients in the chemical composition of the solution along their surfaces, as well as along any nearby container walls. The former leads to self-phoresis, while the latter gives rise to chemi-osmosis, providing an additional contribution to self-motility. Chemi-osmosis strongly depends on the molecular interactions between the diffusing chemical species and the wall. We show analytically, using an approximate "point-particle" approach, that by chemically patterning a planar substrate one can direct the motion of Janus particles: the induced chemi-osmotic flows can cause particles to either "dock" at the chemical step between the two materials, or to follow a chemical stripe. These theoretical predictions are confirmed by full numerical calculations. Generically, docking occurs for particles which tend to move away from their catalytic caps, while stripe-following occurs in the opposite case. Our analysis reveals the physical mechanisms governi...

  12. Surface Patterning of Ceramic Phosphor Plate for Light Extraction

    Science.gov (United States)

    Mao, An

    Light-Emitting Diodes (LEDs) are expected to replace traditional lighting sources in the near future due to their energy-efficiency, optical design flexibility and good reliability over traditional lighting sources. III-V nitride blue LEDs with powdered phosphors have been used commercially to get white emission. However, due to scattering losses, thermal issues as well as the surface reactivity with common encapsulants, LEDs fabricated with powdered phosphors have limitations in achieving high luminous efficacy, high chromatic stability and good color-rendering properties. Solid, non-scattering phosphors could avoid many of these limitations, but issues of light extraction and coupling of excitation radiation to the phosphor require development to insure efficient operation. Photonic crystal structures fabricated into or on non-scattering phosphors can be used to address these challenges. In this thesis, a lift-off process with bilayer resist system is developed to create nanopatterns. A photonic crystal structure is fabricated by low cost molecular transfer lithography (MxL) with bi-layer resist system on non-scattering phosphor plate used for white emission to increase the extraction efficiency. In Chapter 1, some basic background concepts which appear frequently in this thesis are introduced. These concepts include the Stokes shift and backscattering phenomenon for powder phosphors as well as non-scattering phosphors. In Chapter 2, a non-scattering single crystal phosphor with a patterned surface is proposed to replace the powdered phosphors used for color converted LEDs. A non-scattering phosphor YAG:Ce ceramic phosphor plate (CPP) patterned with TiO2 photonic crystal structure is selected for convenience to demonstrate the concept. The physical origin of light extraction of the proposed structure is discussed. The simulation principles and results are discussed in this chapter to find the optimized photonic crystal structure for light extraction. In Chapter 3

  13. Plasma-surface modification vs air oxidation on carbon obtained from peach stone: Textural and chemical changes and the efficiency as adsorbents

    Science.gov (United States)

    De Velasco Maldonado, Paola S.; Hernández-Montoya, Virginia; Montes-Morán, Miguel A.

    2016-10-01

    Carbons were prepared from peach stones (Prunus persica) using different carbonization temperatures (600, 800 and 1000 °C). A selected sample was modified by oxidation using conventional oxidation techniques (thermal treatment in air atmosphere) and with cold oxygen plasma oxidation, under different conditions. Samples were characterized using elemental analysis, FT-IR spectroscopy, nitrogen adsorption isotherms at -196 °C, SEM/EDX analysis, potentiometric titration and XPS analysis. Carbons with and without oxidation were employed in the adsorption of Pb2+ in aqueous solution. Results obtained indicated that the materials with high contents of acidic oxygen groups were more efficient in the removal of Pb2+, values as high as approx. 40 mg g-1 being obtained for the best performing carbon. Textural properties of the original, un-oxidized carbon were significantly altered only after oxidation under air atmosphere at 450 °C. On the other hand, the samples oxidized with plasma show little changes in the textural parameters and a slight increase in the specific surface was observed for the sample treated at high RF power (100 W). Additionally, a significant increment of the oxygen content was observed for the plasma oxidized samples, as measured by XPS.

  14. Application of Response Surface Methodology to Study the Effects of Brisket Fat, Soy Protein Isolate, and Cornstarch on Nutritional and Textural Properties of Rabbit Sausages

    Directory of Open Access Journals (Sweden)

    Joseph M. Wambui

    2017-01-01

    Full Text Available The effects of brisket fat, soy protein isolate, and cornstarch on chemical and textural properties of rabbit sausages were studied using surface response methodology. Sausage samples were prepared using a five-level three-variable Central Composite Rotatable Design with 16 combinations, including two replicates of the center point, carried out in random order. The level of brisket fat (BF, soy protein isolate (SPI, and cornstarch (CS in the sausage formulation ranged within 8.3–16.7%, 0.7–2.3%, and 1.3–4.7%, respectively. Increasing BF decreased moisture and ash contents but increased protein and fat contents of the sausages (p<0.05. Increasing SPI increased moisture content but decreased ash and carbohydrate contents of the sausages (p<0.05. Increasing CS increased carbohydrate content (p<0.05. Increasing BF increased hardness, adhesiveness, cohesiveness, and chewiness but decreased springiness (p<0.05. SPI addition increased springiness but decreased adhesiveness, cohesiveness, and chewiness (p<0.05. In conclusion, varying the levels of BF and SPI had a more significant effect on chemical and textural properties of rabbit sausages than CS.

  15. 太阳能级多晶硅片表面制绒的研究%Research of Texturization on Multi-crystalline Silicon Surface for Solar Cell

    Institute of Scientific and Technical Information of China (English)

    管世兵; 殷伟琦; 严俊; 顾顺超

    2013-01-01

    主要研究多晶硅太阳能电池片工业制绒的酸腐蚀过程,腐蚀液是由HNO3、HF和H2 SiF6组成的混合液,未添加其他试剂作为反应缓释剂;采用SEM和紫外分光光度计对多晶硅片表面制绒形貌进行观察和检测分析.实验过程中,按照工业生产的实际模型,首先研究确定了最佳腐蚀时间为2 min,之后主要研究了酸腐蚀过程中的H2SiF6浓度对多晶硅表面制绒效果的影响,优化得到H2SiF6的最低含量为2%,并确定最佳腐蚀工艺条件,为进一步回收利用腐蚀废液提供依据.%The acid etching process for industrial texturing of multi-crystalline silicon solar cells was studied. In this process, multi-crystalline silicon wafers were textured in acid solution, which was constituted with HNO3, HF and H2SiF6, without any other reagents as release agent. By using the SEM and UV spectrophotometer, detailed study of the surface morphology and optical properties of the different etched surfaces were carried out. During the experiment, the study was focused on the etching time at first, and obtained a best etching time of 2 min. Then the influence of H2SiF6 concentration in the acid solution on multi-crystalline silicon surface texturing effect was studied, with the actual model of industrial productioa From the analytical results, H2SiF6 content and etching conditions were optimized, which would be the basis for further recycling of waste solution.

  16. Nonequilibrium spin texture within a thin layer below the surface of current-carrying topological insulator Bi2 Se3 : A first-pr