Journal articles on the topic 'Associated surface form'
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Turov, V. V., P. P. Gorbyk, T. V. Krupska, S. P. Turanska, V. F. Chekhun, and N. Yu Luk'yanova. "Composite systems for medical purposes, created on the basis of hydrophobic silica." Surface 13(28) (December 30, 2021): 246–75. http://dx.doi.org/10.15407/surface.2021.13.246.
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Composite systems with certain cytotoxic (AM1/lectin) and adsorption (AM1/gelatin) activity have been developed on the basis of methyl silica and protein molecules – lectin and gelatin. For both types of composites, mechanisms of water binding to the surface and methods of transferring of hydrophobic materials into the aquatic environment have been investigated. The state of interfacial water in air, organic and acid media was studied. It has been found that the presence of a hydrophobic component in composites stabilizes of surface water in a weakly associated state, when a significant part of water molecules does not form hydrogen bonds. Liquid hydrophobic medium enhances this effect, and the strong acid (trifluoroacetic), added to it, promotes the transition of water to a strongly associated state. It has been shown that the redistribution of water in the interparticle intervals of AM1 with protein molecules immobilized on their surface changes under the influence of mechanical loads. Mechanoactivated samples are characterized by the possibility of water penetration into the spaces between the primary particles of methyl silica. It has been shown that immobilization of lectin on the surface of AM1 is accompanied by an increase in the interfacial energy gS from 4.1 to 5.2 J/g. This is due to an increase in the concentration of strongly bound water. If we analyze the changes in the distributions of radii R of the clusters of adsorbed water, we can state that in the water adsorbed by native lectin molecules, there are two main maxima at R = 1 and 3 nm. In the immobilized state, the maximum at R = 1 nm is present in both types of water (of different order), but the second maximum is observed only for more ordered associates.
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Keum, Jong Hae. "Every algebraic Kummer surface is the K3-cover of an Enriques surface." Nagoya Mathematical Journal 118 (June 1990): 99–110. http://dx.doi.org/10.1017/s0027763000003019.
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A Kummer surface is the minimal desingularization of the surface T/i, where T is a complex torus of dimension 2 and i the involution automorphism on T. T is an abelian surface if and only if its associated Kummer surface is algebraic. Kummer surfaces are among classical examples of K3-surfaces (which are simply-connected smooth surfaces with a nowhere-vanishing holomorphic 2-form), and play a crucial role in the theory of K3-surfaces. In a sense, all Kummer surfaces (resp. algebraic Kummer surfaces) form a 4 (resp. 3)-dimensional subset in the 20 (resp. 19)-dimensional family of K3-surfaces (resp. algebraic K3 surfaces).
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Robaszewska, Maria. "On some flat connection associated with locally symmetric surface." Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica 13, no. 1 (December 1, 2014): 19–43. http://dx.doi.org/10.2478/aupcsm-2014-0003.
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Abstract For every two-dimensional manifold M with locally symmetric linear connection ∇, endowed also with ∇-parallel volume element, we construct a flat connection on some principal fibre bundle P(M,G). Associated with - satisfying some particular conditions - local basis of TM local connection form of such a connection is an R(G)-valued 1-form build from the dual basis ω1, ω2 and from the local connection form ω of ▽. The structural equations of (M,∇) are equivalent to the condition dΩ-Ω∧Ω=0. This work was intended as an attempt to describe in a unified way the construction of similar 1-forms known for constant Gauss curvature surfaces, in particular of that given by R. Sasaki for pseudospherical surfaces.
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Beiu, Valeriu, Leonard Dăuş, Marilena Jianu, Adela Mihai, and Ion Mihai. "On a Surface Associated with Pascal’s Triangle." Symmetry 14, no. 2 (February 19, 2022): 411. http://dx.doi.org/10.3390/sym14020411.
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An open problem in reliability theory is that of finding all the coefficients of the reliability polynomial associated with particular networks. Because reliability polynomials can be expressed in Bernstein form (hence linked to binomial coefficients), it is clear that an extension of the classical discrete Pascal’s triangle (comprising all the binomial coefficients) to a continuous version (exhibiting infinitely many values in between the binomial coefficients) might be geometrically helpful and revealing. That is why we have decided to investigate the geometric properties of a continuous extension of Pascal’s triangle including: Gauss curvatures, mean curvatures, geodesics, and level curves, as well as their symmetries.
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Pegna, Joseph, and Franz-Erich Wolter. "Surface Curve Design by Orthogonal Projection of Space Curves Onto Free-Form Surfaces." Journal of Mechanical Design 118, no. 1 (March 1, 1996): 45–52. http://dx.doi.org/10.1115/1.2826855.
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A novel technique for designing curves on surfaces is presented. The design specifications for this technique derive from other works on curvature continuous surface fairing. Briefly stated, the technique must provide a computationally efficient method for the design of surface curves that is applicable to a very general class of surface formulations. It must also provide means to define a smooth natural map relating two or more surface curves. The resulting technique is formulated as a geometric construction that maps a space curve onto a surface curve. It is designed to be coordinate independent and provides isoparametric maps for multiple surface curves. Generality of the formulation is attained by solving a tensorial differential equation formulated in terms of local differential properties of the surfaces. For an implicit surface, the differential equation is solved in three-space. For a parametric surface the tensorial differential equation is solved in the parametric space associated with the surface representation. This technique has been tested on a broad class of examples including polynomials, splines, transcendental parametric and implicit surface representations.
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Jiang, Muwei, Han Xie, Jinyu Zhu, Hao Ma, Naiqing Zheng, Siqi Li, Jiahui Xiao, Yirou Wang, Linjun Cai, and Xiaoxia Han. "Molecular form-specific immunoassays for neutrophil gelatinase-associated lipocalin by surface-enhanced Raman spectroscopy." Sensors and Actuators B: Chemical 297 (October 2019): 126742. http://dx.doi.org/10.1016/j.snb.2019.126742.
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Froeliger, Eunice H., and Paula Fives-Taylor. "Streptococcus parasanguisFimbria-Associated Adhesin Fap1 Is Required for Biofilm Formation." Infection and Immunity 69, no. 4 (April 1, 2001): 2512–19. http://dx.doi.org/10.1128/iai.69.4.2512-2519.2001.
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ABSTRACT The sanguis streptococci are primary colonizers of the tooth surface and thus form the foundation for the complex multiple species biofilm known as dental plaque. In addition, these bacteria can colonize native and prosthetic heart valves and are a common cause of endocarditis. Little is known about the molecular mechanisms governing multiple or single species biofilm development within this group of organisms. Using an in vitro assay for biofilm formation, we determined that (i) Streptococcus parasanguis FW213 can form biofilms on inert surfaces such as polystyrene and (ii) environmental and nutritional factors, such as glucose, affect S. parasanguisbiofilm formation. Several isogenic mutants of FW213 were tested in the biofilm assay. Strains containing mutations in fap1, a gene encoding a protein required for assembly of fimbriae, were deficient in biofilm formation. Mutants defective in recA, PepO endopeptidase activity, or the production of a fimbriae-associated protein, FimA, were still capable of biofilm formation. Phase-contrast microscopy was used to follow biofilm development by wild-type andfap1 mutant strains on plastic coverslips over time. Wild-type FW213 attached to the surface, formed aggregates of cells, and eventually formed a dense layer of cells that included microcolonies. In contrast, few fap1 mutant cells were observed attached to the surface, and no cell aggregates or microcolonies were formed. These results suggest that the long peritrichous fimbriae of FW213 are critical for the formation of biofilms on solid surfaces.
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Chandra, Jyotsna, Jasmine D. Patel, Jian Li, Guangyin Zhou, Pranab K. Mukherjee, Thomas S. McCormick, James M. Anderson, and Mahmoud A. Ghannoum. "Modification of Surface Properties of Biomaterials Influences the Ability of Candida albicans To Form Biofilms." Applied and Environmental Microbiology 71, no. 12 (December 2005): 8795–801. http://dx.doi.org/10.1128/aem.71.12.8795-8801.2005.
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ABSTRACT Candida albicans biofilms form on indwelling medical devices (e.g., denture acrylic or intravenous catheters) and are associated with both oral and invasive candidiasis. Here, we determined whether surface modifications of polyetherurethane (Elasthane 80A [E80A]), polycarbonateurethane, and poly(ethyleneterephthalate) (PET) can influence fungal biofilm formation. Polyurethanes were modified by adding 6% polyethylene oxide (6PEO), 6% fluorocarbon, or silicone, while the PET surface was modified to generate hydrophilic, hydrophobic, cationic, or anionic surfaces. Formation of biofilm was quantified by determining metabolic activity and total biomass (dry weight), while its architecture was analyzed by confocal scanning laser microscopy (CSLM). The metabolic activity of biofilm formed by C. albicans on 6PEO-E80A was significantly reduced (by 78%) compared to that of biofilm formed on the nonmodified E80A (optical densities of 0.054 ± 0.020 and 0.24 ± 0.10, respectively; P = 0.037). The total biomass of Candida biofilm formed on 6PEO-E80A was 74% lower than that on the nonmodified E80A surface (0.46 ± 0.15 versus 1.76 ± 0.32 mg, respectively; P = 0.003). Fungal cells were easily detached from the 6PEO-E80A surface, and we were unable to detect C. albicans biofilm on this surface by CSLM. All other surface modifications allowed formation of C. albicans biofilm, with some differences in thearchitecture. Correlation between contact angle and biofilm formation was observed for polyetherurethane substrates (r = 0.88) but not for PET biomaterials (r = −0.40). This study illustrates that surface modification is a viable approach for identifying surfaces that have antibiofilm characteristics. Investigations into the clinical utility of the identified surfaces are warranted.
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Tang, Peifu, Wei Zhang, Yan Wang, Boxun Zhang, Hao Wang, Changjian Lin, and Lihai Zhang. "Effect of Superhydrophobic Surface of Titanium onStaphylococcus aureusAdhesion." Journal of Nanomaterials 2011 (2011): 1–8. http://dx.doi.org/10.1155/2011/178921.
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Despite the systemic antibiotics prophylaxis, orthopedic implants still remain highly susceptible to bacterial adhesion and resulting in device-associated infection. Surface modification is an effective way to decrease bacterial adhesion. In this study, we prepared surfaces with different wettability on titanium surface based on TiO2nanotube to examine the effect of bacterial adhesion. Firstly, titanium plates were calcined to form hydrophilic TiO2nanotube films of anatase phase. Subsequently, the nanotube films and inoxidized titaniums were treated with 1H, 1H, 2H, 2H-perfluorooctyl-triethoxysilane (PTES), forming superhydrophobic and hydrophobic surfaces. Observed by SEM and contact angle measurements, the different surfaces have different characteristics.Staphylococcus aureus(SA) adhesion on different surfaces was evaluated. Our experiment results show that the superhydrophobic surface has contact angles of water greater than 150∘and also shows high resistance to bacterial contamination. It is indicated that superhydrophobic surface may be a factor to reduce device-associated infection and could be used in clinical practice.
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Rogalski, A. A., and S. J. Singer. "An integral glycoprotein associated with the membrane attachment sites of actin microfilaments." Journal of Cell Biology 101, no. 3 (September 1, 1985): 785–801. http://dx.doi.org/10.1083/jcb.101.3.785.
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An integral membrane protein associated with sites of microfilament-membrane attachment has been identified by a newly developed IgG1 monoclonal antibody. This antibody, MAb 30B6, was derived from hybridoma fusion experiments using intact mitotic cells of chick embryo fibroblasts as the immunization vehicle as well as the screening probe for cell surface antigens. In immunofluorescent experiments with fixed cells, MAb 30B6 surface labeling is uniquely correlated with microfilament distributions in the cleavage furrow region of dividing chick embryo fibroblasts and cardiac myocytes in culture. The MAb 30B6 antigen in addition is associated with microfilament-membrane attachment sites in interphase fibroblasts at the dorsal surface, the adhesion plaque region at the ventral surface, and at junction-like regions of cell-cell contact. It is also found co-localized with the membrane-dense plaques of smooth muscle. The MAb 30B6 antigen is expressed in a wide number of chicken cell types (particularly smooth muscle cells, platelets, and endothelial cells), but not in erythrocytes. Some of the molecular characteristics of the MAb 30B6 antigen have been determined from immunoblotting, immunoaffinity chromatography, immunoprecipitation, cell extraction, and charge shift electrophoresis experiments. It is an integral sialoglycoprotein with an apparent molecular mass of 130 kD (reduced form)/107 kD (nonreduced form) in SDS PAGE. Another prominent glycoprotein species with an apparent molecular mass of 175 kD (reduced form)/165 kD (nonreduced form) in SDS PAGE is co-isolated on MAb 30B6 affinity columns, but appears to be antigenically distinct since it is not recognized by MAb 30B6 in immunoblotting or immunoprecipitation experiments. By virtue of its surface distributions relative to actin microfilaments and its integral protein character, we propose that the MAb 30B6 antigen is an excellent candidate for the function of directly or indirectly anchoring microfilaments to the membrane.
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Jamieson, Bruce, and Charles Fierz. "Heat flow from wet to dry snowpack layers and associated faceting." Annals of Glaciology 38 (2004): 187–94. http://dx.doi.org/10.3189/172756404781814762.
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AbstractLayers of faceted crystals adjacent to crusts form the failure layers for some unexpected dry-slab avalanches. This paper focuses on the case of facets that form when dry snow overlies wet snow. From a basic equation for heat flow in solids, the approximate freezing time of the wet layer is derived. Seven experiments are described in which a wet layer was placed between two dry-snowlayers in a cold laboratory. Measured freezing times are comparable to the freezing times from the approximate solution assuming that latent heat from the irreducible water content flowed up. In four of the experiments, evidence of faceting was observed at the base of the upper dry snow layer within 5 hours and before the wet layer froze. In all seven experiments faceting was observed in the upper dry layer after the wet layer froze. Simulations performed with the snow-cover model SNOWPACK yield freezing times that agree reasonably with the approximate solution and allow the influence of various parameters on the results to be explored. In addition, simulated temperatures and grain evolution are compared with observations, showing good agreement.
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Vaux, D. J., and S. Gordon. "Intracellular antigens associated with the cytoplasmic surface of phagolysosomes." Journal of Cell Science 77, no. 1 (August 1, 1985): 109–27. http://dx.doi.org/10.1242/jcs.77.1.109.
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Monoclonal antibodies were prepared to study the cytoplasmic face of latex phagolysosomes isolated from thioglycollate-elicited mouse peritoneal macrophages. Phagolysosomes obtained by sucrose flotation contained latent beta-glucuronidase activity and tightly associated cellular proteins and glycoproteins. Fluorescence-activated cell sorter analysis, scanning and transmission electron microscopy showed that the particle preparation contained greater than 98% monomers and dimers, invested with a smooth layer of membrane and minimally contaminated with cytoplasmic adhesions. Sera for immunized rats bound preferentially to isolated phagolysosomes rather than intact cells and monoclonal antibodies PL-1 and PL-4 were isolated on this basis. Indirect fluorescent, radio- and peroxidase immunobinding assays with intact and methanol-permeabilized cells confirmed that antigens PL-1 and PL-4 were exclusively intracellular and that well-washed phagolysosomes bound both antibodies. These antigens were found in a variety of cells from several species and in macrophages not fed latex. Although the PL-1 antigen could not be immunoprecipitated, intracellular staining was characteristic of intermediate filament distribution, that is, it was in the form of a fine intersecting network, which collapsed, reversibly, in a rim round the nucleus upon treatment with colcemid. The staining pattern was undetectable in cells 1 h after adherence to a substratum, but gradually appeared after 6–12 h. The PL-4 antibody has been shown elsewhere to define a Ca2+-binding protein of approximately 20 000 molecular weight, which is phosphorylated during phagocytosis. This antibody stained stress fibres and revealed a widespread punctate distribution of antigen within cells at all stages after adhesion. The nature of the association between these intracellular antigens and phagolysosomes and their possible role in phagocytosis are not known.
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Metgud, Mrityunjay, Renuka Patil, Vinayak Kumbhojkar, and Niranjan Prabhakar. "Localized Gingival Hyperplasia Associated with Pregnancy." Journal of South Asian Federation of Obstetrics and Gynaecology 2, no. 2 (2010): 155–56. http://dx.doi.org/10.5005/jp-journals-10006-1088.
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ABSTRACT Localized gingival hyperplasia associated with pregnancy is a polypoid form of capillary hemangioma seen as a small, deep red or purplish lesion with a pedunculated base and a lobulated surface, which grows up to several centimeters in size. Its significant incidence of occurrence (1.5-8%) during pregnancy warrants the need for a meticulous oral hygiene care so as to reduce and eliminate the exuberant tissue response to local irritation or trauma seen in such cases. The manuscript highlights one such case report seen in our department.
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Jalid, Abdelilah, Said Hariri, and Jean Paul Senelaer. "Estimation of form deviation and the associated uncertainty in coordinate metrology." International Journal of Quality & Reliability Management 32, no. 5 (May 5, 2015): 456–71. http://dx.doi.org/10.1108/ijqrm-06-2012-0087.
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Purpose – The uncertainty evaluation for coordinate measuring machine metrology is problematic due to the diversity of the parameters that can influence the measurement result. From discrete coordinate data taken on curve (or surface) the software of these machines proceeds to an identification of the measured feature, the parameters of the substitute feature serve in the phase of calculation to estimate the form error of form, and the decisions made based on the result measurement may be outliers when the uncertainty associated to the measurement result is not taken into account. The paper aims to discuss these issues. Design/methodology/approach – The authors relied on the orthogonal distance regression (ODR) algorithm to estimate the parameters of the substitute geometrical elements and their uncertainties. The solution of the problem is resolved by an iterative calculation according to the Levenberg Marquard optimization method. The authors have also presented in this paper the propagation model of uncertainties to the circularity error. This model is based on the law of propagation of the uncertainties defined in the GUM. Findings – This work proposes a model based on ODR to estimates parameters of the substitute geometrical elements and their uncertainties. This contribution allows us to estimate the uncertaintof the form error by applying the law of propagation of uncertainties. An example of calculating the circularity error and the associated uncertainty is explained. This method can be applied to others geometry type: line, plan, sphere, cylinder and cone. Practical implications – This work interested manufacturing firms by allowing them: to meet the normative, which requires that each measurement must be accompanied by its uncertainty-in conformity assessment, the decision-making must take account of this uncertainty to avoid the aberrant decisions. Informing the operators on the capability of their measurement process Originality/value – This work proposes a model based on ODR to estimates parameters of the substitute geometrical elements and its uncertainties. without the hypothesis of small displacements torsor, this method integrates the uncertainty on the coordinates of points and can be applied in any reference placemark. This contribution allows us also to estimate the uncertainty of the form error by applying the law of propagation of uncertainties.
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McCabe, Ryan M., Parker MacCready, and Geno Pawlak. "Form Drag due to Flow Separation at a Headland." Journal of Physical Oceanography 36, no. 11 (November 1, 2006): 2136–52. http://dx.doi.org/10.1175/jpo2966.1.
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Abstract Observational and model estimates of the form drag on Three Tree Point, a headland located in a tidal channel of Puget Sound, Washington, are presented. Subsurface, Three Tree Point is a sloping ridge. Tidal flow over this ridge gives rise to internal lee waves that lead to wave drag and enhanced mixing. At the same time, horizontal flow separation produces a headland eddy that distorts the surface height field in the lee of the point. Two observational methods for estimating the portion of the form drag associated with deformation of the surface height field, referred to here as the “external” form drag, are also introduced. Drogued drifters and ship-mounted acoustic current profiles from different days are used to indirectly map the flood-tide surface height field. Data are derived from a depth shallow enough that baroclinic pressure gradient forcing may be neglected, and yet deep enough that wind stress may also be ignored. This leaves an approximate balance between the acceleration and surface height pressure gradient, permitting, in this case, two independent estimates of the surface height (to within a constant). These fields are used to calculate the external form drag at the headland. Drag estimates from both observational datasets agree well. External form drag decreases offshore of the headland as expected, and is highly dependent on tidal phase, with maximum drag leading peak flood currents by 1–2 h at this location. Form drag is much larger than model estimates of the frictional drag, implying that it is the dominant mechanism extracting energy from the barotropic tide. A kinematic argument is also presented to show why the external form drag should increase in importance relative to the frictional drag as the topographic slope and tidal excursion increase.
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Zhang, Rui, Xing Ai, Yi Wan, Zhanqiang Liu, Dong Zhang, and Sheng Feng. "Surface Corrosion Resistance in Turning of Titanium Alloy." International Journal of Corrosion 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/823172.
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This work addresses the issues associated with implant surface modification. We propose a method to form the oxide film on implant surfaces by dry turning to generate heat and injecting oxygen-rich gas at the turning-tool flank. The morphology, roughness, composition, and thickness of the oxide films in an oxygen-rich atmosphere were characterized using scanning electron microscopy, optical profiling, and Auger electron spectroscopy. Electrochemical methods were used to study the corrosion resistance of the modified surfaces. The corrosion resistance trends, analyzed relative to the oxide film thickness, indicate that the oxide film thickness is the major factor affecting the corrosion resistance of titanium alloys in a simulated body fluid (SBF). Turning in an oxygen-rich atmosphere can form a thick oxide film on the implant surface. The thickness of surface oxide films processed at an oxygen concentration of 80% was improved to 4.6 times that of films processed at an oxygen concentration of 21%; the free corrosion potential shifted positively by 0.357 V, which significantly improved the corrosion resistance of titanium alloys in the SBF. Therefore, the proposed method may (partially) replace the subsequent surface oxidation. This method is significant for biomedical development because it shortens the process flow, improves the efficiency, and lowers the cost.
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Cole, Stephanie J., Angela R. Records, Mona W. Orr, Sara B. Linden, and Vincent T. Lee. "Catheter-Associated Urinary Tract Infection by Pseudomonas aeruginosa Is Mediated by Exopolysaccharide-Independent Biofilms." Infection and Immunity 82, no. 5 (March 4, 2014): 2048–58. http://dx.doi.org/10.1128/iai.01652-14.
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ABSTRACTPseudomonas aeruginosais an opportunistic human pathogen that is especially adept at forming surface-associated biofilms.P. aeruginosacauses catheter-associated urinary tract infections (CAUTIs) through biofilm formation on the surface of indwelling catheters.P. aeruginosaencodes three extracellular polysaccharides, PEL, PSL, and alginate, and utilizes the PEL and PSL polysaccharides to form biofilmsin vitro; however, the requirement of these polysaccharides duringin vivoinfections is not well understood. Here we show in a murine model of CAUTI that PAO1, a strain harboringpel,psl, andalggenes, and PA14, a strain harboringpelandalggenes, form biofilms on the implanted catheters. To determine the requirement of exopolysaccharide duringin vivobiofilm infections, we tested isogenic mutants lacking thepel,psl, andalgoperons and showed that PA14 mutants lacking these operons can successfully form biofilms on catheters in the CAUTI model. To determine the host factor(s) that induces the ΔpelDmutant to form biofilm, we tested mouse, human, and artificial urine and show that urine can induce biofilm formation by the PA14 ΔpelDmutant. By testing the major constituents of urine, we show that urea can induce apel-,psl-, andalg-independent biofilm. Thesepel-,psl-, andalg-independent biofilms are mediated by the release of extracellular DNA. Treatment of biofilms formed in urea with DNase I reduced the biofilm, indicating that extracellular DNA supports biofilm formation. Our results indicate that the opportunistic pathogenP. aeruginosautilizes a distinct program to form biofilms that are independent of exopolysaccharides during CAUTI.
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Cai, Yindi, Yuan-Liu Chen, Yuki Shimizu, So Ito, and Wei Gao. "Molecular dynamics simulation of elastic–plastic deformation associated with tool–workpiece contact in force sensor–integrated fast tool servo." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 232, no. 11 (October 24, 2016): 1893–902. http://dx.doi.org/10.1177/0954405416673116.
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The tool–workpiece interactions when a single-point diamond cutting tool with specific tool edge geometry is made to contact with a copper workpiece are evaluated by the molecular dynamics simulations under different temperatures, boundary conditions and model sizes for ultra-precision microcutting and in-process surface form measurement based on a force sensor–integrated fast tool servo. It is confirmed that the proposed multi-relaxation time method is effective to stabilize the workpiece molecular dynamics model over a wide temperature range up to the room temperature under which a practical microcutting and on-machine surface form metrology process are conducted. The boundary condition and model size of the molecular dynamics model are then optimized to make reliable and cost-effective simulations for evaluation of the elastic–plastic transition contact depth and the corresponding contact force when a diamond tool with a practical edge sharpness of up to 30 nm is employed for microcutting and on-machine surface form metrology.
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Fedele, F., C. Chandre, and M. Farazmand. "Kinematics of fluid particles on the sea surface: Hamiltonian theory." Journal of Fluid Mechanics 801 (July 21, 2016): 260–88. http://dx.doi.org/10.1017/jfm.2016.453.
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We derive the John–Sclavounos equations, describing the motion of a fluid particle on the sea surface, from first principles using Lagrangian and Hamiltonian formalisms applied to the motion of a frictionless particle constrained on an unsteady surface. This framework leads to a number of new insights into the particle kinematics. The main result is that vorticity generated on a stress-free surface vanishes at a wave crest when the horizontal particle velocity equals the crest propagation speed, which is the kinematic criterion for wave breaking. If this holds for the largest crest, then the symplectic two-form associated with the Hamiltonian dynamics reduces instantaneously to that associated with the motion of a particle in free flight, as if the surface did not exist. Further, exploiting the conservation of the Hamiltonian function for steady surfaces and travelling waves, we show that particle velocities remain bounded at all times, ruling out the possibility of the finite-time blowup of solutions.
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Pa, Pai Shan. "Grinding Combination of Electrochemical Smoothing On SKH 51 Surface." Key Engineering Materials 389-390 (September 2008): 410–16. http://dx.doi.org/10.4028/www.scientific.net/kem.389-390.410.
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A new finish mode combination of grinding and electrochemical smoothing executes a finish processes on SKH 51 surface is investigated. In the experiment, a high rotational speed of finish tool produces a better finish. A thin electrode associated with higher current density provides a larger discharge space for a better finish. The design change from a full form finish-tool to a partial finish-tool leads more discharge space, which creates better finishes than full form tool. It is a great contribution that the synchronous finish processes has a high efficiency than the electrochemical smoothing to make the workpiece surface smooth and bright.
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Pentecost, Allan. "Cyanobacteria associated with hot spring travertines." Canadian Journal of Earth Sciences 40, no. 11 (November 1, 2003): 1447–57. http://dx.doi.org/10.1139/e03-075.
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Cyanobacteria are the major oxygenic photosynthetic microorganisms of hot spring travertines. This review describes the known cyanobacterium flora of travertine-depositing waters > 37 °C. The communities develop either upon (epilithon) or within (endolithon) the travertine surface, where they may influence the travertine fabric by providing nucleation sites for calcium carbonate. Mat photosynthesis locally increases the amount of travertine deposited, but the importance of photosynthesis in travertine deposition is rarely significant because the main loss of CO2is by atmospheric evasion of the hot, CO2-rich waters. The Oscillatoriales are the most important group of cyanobacteria in terms of their biomass, but the taxonomy of the order is in a state of chaos. Molecular methods will ultimately disclose the true affinities of the organisms but, at present, the use of form-taxa based upon morphological characters provides a practical alternative. Identification of fossilized cyanobacteria is problematic since few of the key characters survive as fossils. The known cyanobacterium flora is tabulated and an analytical key provided to identify the form-taxa of hot spring travertines.
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Magirl, C. S., and F. P. Incropera. "Flow and Morphological Conditions Associated With Unidirectional Solidification of Aqueous Ammonium Chloride." Journal of Heat Transfer 115, no. 4 (November 1, 1993): 1036–43. http://dx.doi.org/10.1115/1.2911358.
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Using a 27 percent aqueous ammonium chloride solution as a transparent analog, shadowgraph and dye injection techniques have been employed to observe flow and morphological conditions associated with unidirectional solidification (UDS) from below. Dendritic crystals, which initially form at the cold surface, reject lighter, solute deficient fluid, and the attendant instability is manifested by finger-type double-diffusive convection phenomena. As a two-phase (solid/liquid), or mushy, region grows from the bottom surface, vertical channels develop in the mushy region, and solutal plumes that emanate from the channels are characterized primarily by an ascending, oscillatory motion and secondarily by wisps of fluid, which detach and descend from bends in the plumes. In time, double-diffusive convection layers also form in the melt. From a numerical simulation of the process, it is concluded that the channels originate from perturbations at the liquid interface, which cause localized remelting and create conditions conducive to development of the channels.
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Bayard, Pierre, Victor Patty, and Federico Sánchez-Bringas. "On Lorentzian surfaces in ℝ2,2." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 147, no. 1 (January 6, 2017): 61–88. http://dx.doi.org/10.1017/s0308210516000147.
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We study the second-order invariants of a Lorentzian surface in ℝ2,2, and the curvature hyperbolas associated with its second fundamental form. Besides the four natural invariants, new invariants appear in some degenerate situations. We then introduce the Gauss map of a Lorentzian surface and give an extrinsic proof of the vanishing of the total Gauss and normal curvatures of a compact Lorentzian surface. The Gauss map and the second-order invariants are then used to study the asymptotic directions of a Lorentzian surface and discuss their causal character. We also consider the relation of the asymptotic lines with the mean directionally curved lines. We finally introduce and describe the quasi-umbilic surfaces, and the surfaces whose four classical invariants vanish identically.
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Zhu, Lin, Jens Kreth, Sarah E. Cross, James K. Gimzewski, Wenyuan Shi, and Fengxia Qi. "Functional characterization of cell-wall-associated protein WapA in Streptococcus mutans." Microbiology 152, no. 8 (August 1, 2006): 2395–404. http://dx.doi.org/10.1099/mic.0.28883-0.
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Streptococcus mutans is known as a primary pathogen responsible for dental caries. One of the virulence factors of S. mutans in cariogenicity is its ability to attach to the tooth surface and form a biofilm. Several surface proteins have been shown to be involved in this process. A 29 kDa surface protein named wall-associated protein A (WapA, antigen A or antigen III), was previously used as a vaccine in animal studies for immunization against dental caries. However, the function of WapA in S. mutans is still not clear. This study characterized the function of WapA in cell surface structure and biofilm formation. Compared to the wild-type, the wapA mutant had much-reduced cell chain length, diminished cell–cell aggregation, altered cell surface ultrastructure, and unstructured biofilm architecture. Furthermore, in vivo force spectroscopy revealed that the cell surface of the wapA mutant was less sticky than that of the wild-type cells. More interestingly, these phenotypic differences diminished as sucrose concentration in the medium was increased to 0.5 %. Real-time RT-PCR analysis demonstrated that sucrose strongly repressed wapA gene expression in both planktonic and biofilm cells. These results suggest that the WapA protein plays an important structural role on the cell surface, which ultimately affects sucrose-independent cell–cell aggregation and biofilm architecture.
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Savistky, Daniel, and Michael Morabito. "Surface Wave Contours Associated with the Forebody Wake of Stepped Planing Hulls." Marine Technology and SNAME News 47, no. 01 (January 1, 2010): 1–16. http://dx.doi.org/10.5957/mtsn.2010.47.1.1.
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Results of an extensive series of model tests that define the longitudinal surface wake profiles aft of prismatic hulls having deadrise angles of 10º, 20º and 30º are presented. Empirical equations are developed that quantitatively define these profiles and are in a form that can be easily applied by designers of stepped planing hulls. These equations are applicable for an expected range of variations in trim angle, speed coefficient, and loading coefficient typical for these hulls. A brief introduction to the concept and to the hydrodynamic advantages of stepped planing hulls is presented to orient the reader as to the importance of wake data in their design. Examples are presented that illustrate the application of these wake data for stepped planing hulls with wetted forebody chine to achieve maximum hydrodynamic lift/drag ratios. Finally experimental results are presented that illustrate the potential resistance penalty associated with the operation of chines dry forebodies where the stagnation line crosses the step.
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Dobrzański, Paweł, and Paweł Pawlus. "Modification of Robust Filtering of Stratified Surface Topography." Metrology and Measurement Systems 20, no. 1 (March 1, 2013): 107–18. http://dx.doi.org/10.2478/mms-2013-0010.
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Abstract Various components of surface texture are identified, namely form, waviness and roughness. Separation of these components is done by digital filtering. Several problems exist during analysis of two-process surfaces. Therefore the Gaussian robust profile filtering technique was established and has been studied here. The computer generated 2D profiles and 3D surface topographies having triangular scratches as well as measured stratified surfaces were subjected to filtration. However even robust filter applications cause distortion of profiles having valleys wider than 100 μm. In order to minimize the distortion associated with wide and deep valleys, the robust filter should be modified. A special procedure was elaborated for minimizing distortion of roughness profiles caused by filtration. Application of this method to analyses of several profiles was presented. The difference between 1-D and 2-D filtering of surface topography using the same kind of filter was discussed. As a result we found that modification of a 2-D surface topography filter was not necessary.
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Dean, M. F., H. Martin, and P. A. Sansom. "Characterization of a thioredoxin-related surface protein." Biochemical Journal 304, no. 3 (December 15, 1994): 861–67. http://dx.doi.org/10.1042/bj3040861.
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A surface-associated sulphydryl (thiol) protein (SASP) constitutively present in most nucleated cells was purified from human THP-1 monocytes and rat C6 glioma cells. The human protein was similar in mass and isoelectric point and had the same N-terminal amino acid sequence to adult T-cell leukemia-derived factor (ADF), a growth factor secreted by human lymphoid cells which is able to induce increased expression of interleukin-2 receptors. A further internal amino acid sequence, determined following cleavage of human SASP with cyanogen bromide, was also identical to the corresponding sequence deduced for ADF. Samples of SASP were able to reductively depolymerize human immunoglobulin, a property shared with thioredoxin, a ubiquitous protein, almost identical to ADF, with an essential function in many thiol-dependent reducing reactions. Furthermore, SASP purified from rat C6 glioma cells had an identical N-terminal amino acid sequence to that deduced for rat liver thioredoxin, showing that they were both members of the same family of proteins. The use of membrane-impermeable thiol reagents indicated that SASP was predominantly a cell-surface protein, and was not normally secreted. This SASP protein appeared to be a surface-associated form of thioredoxin that was constitutively present in a wide range of cells and was related to ADF, a secreted form of the same protein.
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CHEN, XIAOJUN, and TAKUMA KIMURA. "FINITE ELEMENT SURFACE FITTING FOR BRIDGE MANAGEMENT." International Journal of Information Technology & Decision Making 05, no. 04 (December 2006): 671–81. http://dx.doi.org/10.1142/s0219622006002180.
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We propose a new finite element surface fitting method which can handle very large databases. This method uses finite element discretization to find an approximation of a smooth function which minimizes a sum of data residuals and second derivatives under some constraints on data. The finite element discretization derives a large scale constrained quadratic program, which can be reformulated as a system of piecewise linear equations. We develop a preconditioned Newton method to solve the system efficiently. We apply this method to form surfaces over Aomori Region in Japan by geographic databases, such that every bridge became associated with environmental information.
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Jeznach, Oliwia, Dorota Kolbuk, and Paweł Sajkiewicz. "Aminolysis of Various Aliphatic Polyesters in a Form of Nanofibers and Films." Polymers 11, no. 10 (October 14, 2019): 1669. http://dx.doi.org/10.3390/polym11101669.
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Surface functionalization of polymer scaffolds is a method used to improve interactions of materials with cells. A frequently used method for polyesters is aminolysis reaction, which introduces free amine groups on the surface. In this study, nanofibrous scaffolds and films of three different polyesters–polycaprolactone (PCL), poly(lactide-co-caprolactone) (PLCL), and poly(l-lactide) (PLLA) were subjected to this type of surface modification under the same conditions. Efficiency of aminolysis was evaluated on the basis of ninhydrin tests and ATR–FTIR spectroscopy. Also, impact of this treatment on the mechanical properties, crystallinity, and wettability of polyesters was compared and discussed from the perspective of aminolysis efficiency. It was shown that aminolysis is less efficient in the case of nanofibers, particularly for PCL nanofibers. Our hypothesis based on the fundamentals of classical high speed spinning process is that the lower efficiency of aminolysis in the case of nanofibers is associated with the radial distribution of crystallinity of electrospun fiber with more crystalline skin, strongly inhibiting the reaction. Moreover, the water contact angle results demonstrate that the effect of free amino groups on wettability is very different depending on the type and the form of polymer. The results of this study can help to understand fundamentals of aminolysis-based surface modification.
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Hahn, Jack. "One-Piece Root-Form Implants: A Return to Simplicity." Journal of Oral Implantology 31, no. 2 (April 1, 2005): 77–84. http://dx.doi.org/10.1563/0-737.1.
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Abstract Immediately loaded 1-piece dental implants were a standard treatment modality more than 30 years ago and, on occasion, resulted in excellent clinical successes. However, this technology also became associated with significant failure rates and fell out of favor. Since then, understanding of the site requirements and placement procedures necessary to ensure primary stability have advanced considerably. Implant designs and surface treatments also have evolved. In light of this greater understanding, a 1-piece root-form implant system has been developed. This article describes 4 clinical cases in which use of the new system was employed. In each case, the results included excellent stability, esthetics, and patient satisfaction.
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Polyakov, Maxim V., and Peter Schweitzer. "Forces inside hadrons: Pressure, surface tension, mechanical radius, and all that." International Journal of Modern Physics A 33, no. 26 (September 18, 2018): 1830025. http://dx.doi.org/10.1142/s0217751x18300259.
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The physics related to the form factors of the energy–momentum tensor spans a wide spectrum of problems, and includes gravitational physics, hard-exclusive reactions, hadronic decays of heavy quarkonia, and the physics of exotic hadrons described as hadroquarkonia. It also provides access to the “last global unknown property:” the D-term. We review the physics associated with the form factors of the energy–momentum tensor and the D-term, their interpretations in terms of mechanical properties, their applications, and the current experimental status.
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Gritsans, Armands, and Felix Sadyrbaev. "TWO-PARAMETER NONLINEAR OSCILLATIONS: THE NEUMANN PROBLEM." Mathematical Modelling and Analysis 16, no. 1 (April 8, 2011): 23–38. http://dx.doi.org/10.3846/13926292.2011.559449.
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Boundary value problems of the form are considered, where In our considerations functions f and g are generally nonlinear. We give a description of a solution set of the problem (i), (ii). It consist of all triples () such that (λ,μ,x(t)) nontrivially ′solves the problem(i),(ii) and |x (z)| = α at zero points z of the function x(t) (iii). We show that this solution set is a union of solution surfaces which are centro-affine equivalent. Each solution surface is associated with nontrivial solutions with definite nodal type. Properties of solution surfaces are studied. It is shown, in particular, that solution surface associated with solutions with exactly i zeroes in the interval (a,b) is centro-affne equivalent to a solution surface of the Dirichlet problem (i), x(a) = 0 = x(b), (iii) corresponding to solutions with odd number of zeros 2j − 1 (i ≠ 2j)in the interval (a,b).
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Šuba, Jaroslav, Iveta Štyriaková, Igor Štyriak, and Darina Štyriaková. "Microbial Dissolution of Iron Surface Coatings in Industrial Minerals." Solid State Phenomena 262 (August 2017): 255–58. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.255.
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The purpose of this work was to investigate the phenomenon of microbial iron reduction in industrial minerals and materials. These materials are generally not pure, often associated with impurities usually in the form of Fe3+. In all cases, the presence of iron affects the colour and the physical properties of the mineral and therefore lowers their industrial value and limits their application. In this study bentonite, kaolin and quartz sand sample were used for the experiments and compared in effectiveness of iron dissolution. The experimental results showed that after 30 days of bioleaching process, bacteria are able to remove 9.29% of Fe occurring in the kaolin sample (K-I) in amorphous form of oxyhydroxides and approximately 12% of Fe from the bentonite sample (B-JP) also in amorphous form of oxyhydroxides. In the quartz sand sample C3-15D, the concentration of Fe decreased by 15% after 15 days of bioleaching process and in the sample C3-30D after 30 days of bioleaching process by 24.7%.
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Stanisˇic´, M. M., and K. C. Gupta. "Closed-Form Solutions to the Spherical Joint Attachment Problem." Journal of Mechanical Design 114, no. 2 (June 1, 1992): 269–73. http://dx.doi.org/10.1115/1.2916942.
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This paper presents closed-form solutions to the problem of defining the attachment of a spherical joint (a ball and socket) in a spatial linkage. The defined attachment should minimize the opening angle of the socket, maximizing the ball retention capability. Previous solutions to this problem have used iterative searching techniques, which are computationally intense. In this paper the problem is reformulated as a surface fitting problem. Two formulations are presented, both of which require the solution of the associated eigenvalue problems. The eigenvectors correspond to the central axis of symmetry for the socket opening. A numerical example is presented to compare the results obtained by these formulations with those available in the literature.
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DELİCEOĞLU, A. "Topology of two-dimensional flow associated with degenerate dividing streamline on a free surface." European Journal of Applied Mathematics 24, no. 1 (September 25, 2012): 77–101. http://dx.doi.org/10.1017/s0956792512000319.
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Topology of two-dimensional flow associated with degenerate dividing streamline on a free surface is analysed from a topological point of view by considering the critical point concept. Streamline patterns and their bifurcations in the vicinity of a free surface were investigated by Brøns (Brøns, M. (1994) Topological fluid dynamics of interfacial flows. Phys. Fluids6, 2730–2736). Brøns's work is extended to the case of a stream function, including the fourth-order normal form approach. From this, a complete description of bifurcations which can occur in two-dimensional incompressible flow is obtained up to codimension three. The theory is applied to the patterns found numerically in a roll coater.
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Cowie, R., J. Graham, and S. Gielen. "The Contribution of Provisual Actions to Judgments of form in Depth." Perception 25, no. 1_suppl (August 1996): 30. http://dx.doi.org/10.1068/v96p0118.
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An action is ‘provisual’ if it is meant to improve the information that can be obtained through vision. Eye and head movements are the most studied examples, but it is more a general phenomenon, including for example manoeuvring for position. The effect of allowing provisual manipulation was compared with more traditional ways of facilitating perception of form in depth. Stimuli were parallel projections of a square and a rectangle (whose proportions ranged from 1 : 1.1 to 1 : 1.4), both slanted in depth, presented side by side on a computer screen. Nine subjects judged which was which. Information varied along three dimensions: (1) surface type—outline, shaded, and textured; (2) dimensionality—structures were either 2-D, or had a ‘leg’ at each corner (normal to the surface); (3) movement—static, passive (rotary) motion, and provisual (where subjects manoeuvred the objects using a mouse). Surface effects were weak ( p=0.047). Dimensionality had a stronger effect ( p=0.0003). The effect of passive movement was comparable, but provisual manipulation gave much better discrimination, irrespective of surface or dimensionality, reaching a ceiling with rectangle proportions around 1 : 1.3. The subjects' usual strategy was to manoeuvre structures into a roughly frontoparallel position. The judgment is almost trivial in that position, but finding it is an interesting theoretical problem—particularly given the demonstration that it can be achieved from parallel projections of a few coplanar points. A model is being developed based on neural networks capable of learning the probabilities associated with viewpoints and trajectories.
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Palaniyar, Nades, Ross A. Ridsdale, Stephen A. Hearn, Yew Meng Heng, F. Peter Ottensmeyer, Fred Possmayer, and George Harauz. "Filaments of surfactant protein A specifically interact with corrugated surfaces of phospholipid membranes." American Journal of Physiology-Lung Cellular and Molecular Physiology 276, no. 4 (April 1, 1999): L631—L641. http://dx.doi.org/10.1152/ajplung.1999.276.4.l631.
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Pulmonary surfactant, a mixture of lipids and surfactant proteins (SPs), plays an important role in respiration and gas exchange. SP-A, the major SP, exists as an octadecamer that can self-associate to form elongated protein filaments in vitro. We have studied here the association of purified bovine SP-A with lipid vesicle bilayers in vitro with negative staining with uranyl acetate and transmission electron microscopy. Native bovine surfactant was also examined by transmission electron microscopy of thinly sectioned embedded material. Lipid vesicles made from dipalmitoylphosphatidylcholine and egg phosphatidylcholine (1:1 wt/wt) generally showed a smooth surface morphology, but some large vesicles showed a corrugated one. On the smooth-surfaced vesicles, SP-As primarily interacted in the form of separate octadecamers or as multidirectional protein networks. On the surfaces of the striated vesicles, SP-As primarily formed regularly spaced unidirectional filaments. The mean spacing between adjacent striations and between adjacent filaments was 49 nm. The striated surfaces were not essential for the formation of filaments but appeared to stabilize them. In native surfactant preparations, SP-A was detected in the dense layers. This latter arrangement of the lipid bilayer-associated SP-As supported the potential relevance of the in vitro structures to the in vivo situation.
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Mizunoe, Yoshimitsu, Sun Nyunt Wai, Akemi Takade, and Shin-Ichi Yoshida. "Isolation and Characterization of Rugose Form of Vibrio cholerae O139 Strain MO10." Infection and Immunity 67, no. 2 (February 1, 1999): 958–63. http://dx.doi.org/10.1128/iai.67.2.958-963.1999.
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ABSTRACT An extracellular exopolysaccharide (slime) is produced byVibrio cholerae O139 MO10 in response to nutrient starvation. The presence of this slime layer on the cell surface and its subsequent release have been shown to be associated with biofilm formation and the change from a normal smooth colony morphology to a rugose one. An immunoelectron microscopic examination demonstrated that there is an epitope common to the exopolysaccharide antigen of V. cholerae O1 and that of O139 MO10.
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Gomes, João Henrique Gaia, Marcos Gervasio Pereira, Fabiana da Costa Barros, Cristiane Figueira da Silva, Vanessa Aparecida Freó, and Alexandre dos Santos Medeiros. "Edaphic attributes in pedoforms of gullies, in the Southeast region of Brazil." Revista em Agronegócio e Meio Ambiente 14, no. 4 (July 31, 2021): 1–13. http://dx.doi.org/10.17765/2176-9168.2021v14n4e7687.
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Water erosion acts as the main form of soil degradation, promoting the release of particles that associated with factors such as climate, relief, soil vegetation and use and occupation favor this process. This study aimed to evaluate whether gullies are more likely to be present in a specific type of landform and how physical and chemical soil characteristics vary between the internal and external environments of concave and convex gullies. The study was performed in the Cachimbal River sub-basin, Pinheiral (RJ). Gullies were mapped and the quantitative and qualitative evaluations (occurrence in concave or convex surface). For each type of landform, one gully was selected. Soil samples (disturbed and undisturbed) were collected from the internal and external surfaces of each gully at a depth of 0-10 cm and soil chemical and physical characteristics were determined. More gullies were present in convex landforms and differences in soil characteristics were observed between the internal and external gully surfaces, but not between different landforms. Ca+2, S value, H+Al, T value, Mg+2, TOC and K+ were associated with the external surface, and P, Al+3, aluminum saturation, V%, and pH with the internal surface. Natural and total clay content, and soil and particle density were the physical characteristics associated with the external surface, and total and fine sand content, porosity, degree of flocculation, and silt content with the internal surface.
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Lee, Seungbok, and Peter A. Kolodziej. "The plakin Short Stop and the RhoA GTPase are required for E-cadherin-dependent apical surface remodeling during tracheal tube fusion." Development 129, no. 6 (March 15, 2002): 1509–20. http://dx.doi.org/10.1242/dev.129.6.1509.
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Cells in vascular and other tubular networks require apical polarity in order to contact each other properly and to form lumen. As tracheal branches join together in Drosophila melanogaster embryos, specialized cells at the junction form a new E-cadherin-based contact and assemble an associated track of F-actin and the plakin Short Stop (shot). In these fusion cells, the apical surface determinant Discs Lost (Dlt) is subsequently deposited and new lumen forms along the track. In shot mutant embryos, the fusion cells fail to remodel the initial E-cadherin contact, to make an associated F-actin structure and to form lumenal connections between tracheal branches. Shot binding to F-actin and microtubules is required to rescue these defects. This finding has led us to investigate whether other regulators of the F-actin cytoskeleton similarly affect apical cell surface remodeling and lumen formation. Expression of constitutively active RhoA in all tracheal cells mimics the shot phenotype and affects Shot localization in fusion cells. The dominant negative RhoA phenotype suggests that RhoA controls apical surface formation throughout the trachea. We therefore propose that in fusion cells, Shot may function downstream of RhoA to form E-cadherin-associated cytoskeletal structures that are necessary for apical determinant localization.
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Xu, Xiao Cun, Zhe Jun Yuan, and Yu Quan Chen. "The New Technology of Floating Polishing of Large Die Surfaces." Key Engineering Materials 315-316 (July 2006): 294–98. http://dx.doi.org/10.4028/www.scientific.net/kem.315-316.294.
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During the transferring process of the large die surfaces, there are extensive needs of die surface polishing. Since almost large die surfaces are free-form surfaces, currently, these are almost manually implemented. In order to overcome this barrier, this paper focuses on a new technology of floating polishing, including a) the design of polisher body which has five degrees of freedom and realize the floating polishing while keep the polishing head being indifference equilibrium within the working range, b) normal force of polishing head on die surface analyses and experimental verification by using the slip line field method, and c) establishments of the interference boundaries between dies surface features and polishing head. The research achievements will be used for the development of a portable, state-of-the-art polishing machine and the optimization of the associated polishing process parameters in near future.
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Smith, Daniel R., Manuel Maestre-Reyna, Gloria Lee, Harry Gerard, Andrew H. J. Wang, and Paula I. Watnick. "In situ proteolysis of theVibrio choleraematrix protein RbmA promotes biofilm recruitment." Proceedings of the National Academy of Sciences 112, no. 33 (August 3, 2015): 10491–96. http://dx.doi.org/10.1073/pnas.1512424112.
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The estuarine gram-negative rod and human diarrheal pathogenVibrio choleraesynthesizes a VPS exopolysaccharide-dependent biofilm matrix that allows it to form a 3D structure on surfaces. Proteins associated with the matrix include, RbmA, RbmC, and Bap1. RbmA, a protein whose crystallographic structure suggests two binding surfaces, associates with cells by means of a VPS-dependent mechanism and promotes biofilm cohesiveness and recruitment of cells to the biofilm. Here, we show that RbmA undergoes limited proteolysis within the biofilm. This proteolysis, which is carried out by the hemagglutinin/protease and accessory proteases, yields the 22-kDa C-terminal polypeptide RbmA*. RbmA* remains biofilm-associated. Unlike full-length RbmA, the association of RbmA* with cells is no longer VPS-dependent, likely due to an electropositive surface revealed by proteolysis. We provide evidence that this proteolysis event plays a role in recruitment of VPS−cells to the biofilm surface. Based on our findings, we propose that association of RbmA with the matrix reinforces the biofilm structure and leads to limited proteolysis of RbmA to RbmA*. RbmA*, in turn, promotes recruitment of cells that have not yet initiated VPS synthesis to the biofilm surface. The assignment of two functions to RbmA, separated by a proteolytic event that depends on matrix association, dictates an iterative cycle in which reinforcement of recently added biofilm layers precedes the recruitment of new VPS−cells to the biofilm.
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Goldman, Robert D., and Jonathan C. R. Jones. "On the use of human autoantibodies in the determination of cytoskeletal-cell surface interactions." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 16–17. http://dx.doi.org/10.1017/s0424820100084387.
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Intermediate filaments (IF) form a cytoskeletal system which appears to connect the nuclear surface with the cell surface. At the level of the nuclear surface, IF appear to be anchored to the outer nuclear envelope membrane and/or to nuclear pore complexes. In turn, these cytoplasmic IF are also thought to be linked in some unknown fashion to the nuclear lamina which is composed primarily of a polymer of the Type V IF proteins, the nuclear lamins. At the level of the cell surface, IF are connected to plasma membrane associated structures at sites of cell-cell and cellsubstrate adhesion. In epithelial cells, adhesion sites between cells include desmosomes and the major adhesion sites between basal cell surfaces and the basement membrane are termed hemidesmosomes.
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Brown, Helen L., Mark Reuter, Louise J. Salt, Kathryn L. Cross, Roy P. Betts, and Arnoud H. M. van Vliet. "Chicken Juice Enhances Surface Attachment and Biofilm Formation of Campylobacter jejuni." Applied and Environmental Microbiology 80, no. 22 (September 5, 2014): 7053–60. http://dx.doi.org/10.1128/aem.02614-14.
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ABSTRACTThe bacterial pathogenCampylobacter jejuniis primarily transmitted via the consumption of contaminated foodstuffs, especially poultry meat. In food processing environments,C. jejuniis required to survive a multitude of stresses and requires the use of specific survival mechanisms, such as biofilms. An initial step in biofilm formation is bacterial attachment to a surface. Here, we investigated the effects of a chicken meat exudate (chicken juice) onC. jejunisurface attachment and biofilm formation. Supplementation of brucella broth with ≥5% chicken juice resulted in increased biofilm formation on glass, polystyrene, and stainless steel surfaces with fourC. jejuniisolates and oneC. coliisolate in both microaerobic and aerobic conditions. When incubated with chicken juice,C. jejuniwas both able to grow and form biofilms in static cultures in aerobic conditions. Electron microscopy showed thatC. jejunicells were associated with chicken juice particulates attached to the abiotic surface rather than the surface itself. This suggests that chicken juice contributes toC. jejunibiofilm formation by covering and conditioning the abiotic surface and is a source of nutrients. Chicken juice was able to complement the reduction in biofilm formation of an aflagellated mutant ofC. jejuni, indicating that chicken juice may support food chain transmission of isolates with lowered motility. We provide here a useful model for studying the interaction ofC. jejunibiofilms in food chain-relevant conditions and also show a possible mechanism forC. jejunicell attachment and biofilm initiation on abiotic surfaces within the food chain.
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Pa, Pai Shan. "Design of Sword-Form Electrode and Ultrasonic-Aid in Electrochemical Finishing of AISI 4340 Surface." Key Engineering Materials 364-366 (December 2007): 674–79. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.674.
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It is difficult to execute the polishing process for swords surface. This study provides a design of sword-form electrode and a new area finishing process using an ultrasonic energy transmitted into the electrolyte to assist the process of electrochemical finishing on the surface of nickel chromium steels beyond traditional polishing process of sword surface instead of the conventional hand or machines surface finishing. The surface of the sword is electrochemically finished by different types of feeding electrodes as a finishing operation. In the experiment, four types of electrode were used with continuous direct current and axial electrode feed applied. The controlled factors included the chemical composition and concentration of the electrolyte, die material, initial gap width, and flow rate of electrolyte. The experimental parameters were current rating, feed rate of electrode, frequency and power level of ultrasonics, and electrode geometry. The higher current rating with ultrasonic assistance can avoid the difficulty of dregs discharge, thus reducing the finishing time. For the design of electrodes, an electrode of arc-end shape with small end radius and small wedge angle provides larger discharge space and better finishing effect. The electrode of round-pin shape with semicircular end is associated with higher current density and provides more opening discharge space and performs best. A low-cost and effective finishing process of the sword surface is presented. It is a great contribution that the ultrasonic-aided electrochemical finishing after sword finish just needs quite a shorter time than manual or machine polishing to make the surface of swords smooth and bright.
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Akin, Cem, Gerard Fumo, Akif S. Yavuz, Peter E. Lipsky, Len Neckers, and Dean D. Metcalfe. "A novel form of mastocytosis associated with a transmembrane c-kit mutation and response to imatinib." Blood 103, no. 8 (April 15, 2004): 3222–25. http://dx.doi.org/10.1182/blood-2003-11-3816.
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Abstract Mutational analysis of the c-kit gene in a patient with a previously undescribed variant of mast cell disease revealed a germline mutation, Phe522Cys, within the transmembrane portion of the Kit receptor protein. Transfection experiments revealed that the mutation caused ligand-independent autophosphorylation of Kit, which was inhibited by the tyrosine kinase inhibitor imatinib mesylate. The patient's bone marrow biopsy and aspirate displayed unique pathologic features with the presence of excessive numbers of mature-appearing mast cells and absence of aberrant mast cell surface expression of CD2, CD25, and CD35. Therapy with imatinib mesylate resulted in a dramatic improvement in mast cell burden and clinical symptoms. These results highlight the significance of the transmembrane region of Kit in activation of the molecule and its importance in mast cell development and suggest a role for screening for transmembrane c-kit mutations in patients with mastocytosis in association with the decision to use imatinib mesylate. (Blood. 2004;103:3222-3225)
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Hall, R. W., and M. D. Savage. "Two-Dimensional Elastohydrodynamic Lubrication Part 1: The Associated Dry Contact Problem." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 202, no. 5 (September 1988): 347–53. http://dx.doi.org/10.1243/pime_proc_1988_202_132_02.
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Associated with each elastohydrodynamic (EHD) lubrication problem there is a dry contact problem with the same contact zone, |x| a, surface displacement, υ(x), and pressure distribution, p(x). This paper considers the two-dimensional dry contact problem and shows how Poritsky's closed-form solution can be used to derive results of fundamental importance to EHD lubrication. In particular, it is shown that singularities in pressure and pressure gradient arise from discontinuities in dυ/dx and d2υ/dx2. In addition, with υ(x) expressed as a Fourier cosine series of the form υ(x) = Σn Bn cos nη (where x = a cos η, 0 ≤ η ≤ π), it follows that at the end points of the contact zone, Reynolds boundary conditions are natural conditions yielding straightforward conditions on the Fourier coefficients, Bn.
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Matsuno, Osamu, Eishi Miyazaki, Shinichi Nureki, Takuya Ueno, Masaru Ando, and Toshihide Kumamoto. "Soluble CD26 is inversely Associated with Disease Severity in Patients with Chronic Eosinophilic Pneumonia." Biomarker Insights 1 (January 2006): 117727190600100. http://dx.doi.org/10.1177/117727190600100012.
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Backgrounds CD26, a multifunctional T cell surface glycoprotein, is a type II transmembrane protein containing only six amino acid residues in its cytoplasmic region. In addition to its membrane form, CD26 exists in plasma in a soluble form (sCD26), which is thought to be the extracellular domain of the molecule cleaved from the cell surface. Recent studies indicated CD26 have an important role in the pathogenesis of asthma, known as Th2 like disease. The function of CD26 in the esosinophlic lung disease is not well understood. Methods Serum sCD26 was determined by enzyme-linked immunosorbent assay in patients with acute eosinophilic pneumonia, chronic eosinophilic pneumonia (CEP), and sarcoidosis, and in healthy volunteers, to establish its value for discriminating between disease entities and as marker of disease activity. Results Soluble CD26 was significantly reduced in CEP and was related to disease severity. In particular, sCD26 was inversely correlated with arterial oxygen tension in CEP. Conclusion Serum levels of sCD26 might appear to be useful as a new marker of CEP disease activity.
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Boier-Martin, Ioana, Remi Ronfard, and Fausto Bernardini. "Detail-Preserving Variational Surface Design With Multiresolution Constraints." Journal of Computing and Information Science in Engineering 5, no. 2 (February 23, 2005): 104–10. http://dx.doi.org/10.1115/1.1891824.
Full textAbstract:
We present a variational framework for rapid shape prototyping. The modeled shape is represented as a Catmull-Clark multiresolution subdivision surface which is interactively deformed by direct user input. Free-form design goals are formulated as constraints on the shape and the modeling problem is cast into a constrained optimization one. The focus of this paper is on handling multiresolution constraints of different kinds and on preserving surface details throughout the deformation process. Our approach eliminates the need for an explicit decomposition of the input model into frequency bands and the overhead associated with saving and restoring high-frequency detail after global shape fairing. Instead, we define a deformation vector field over the model and we optimize its energy. Surface details are considered as part of the rest shape and are preserved during free-form model editing. We explore approximating the solution of the optimization problem to various degrees to balance trade-offs between interactivity and accuracy of the results.
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Žagar, Tomaž, Miha Pavšič, and Aljaž Gaber. "Destabilization of EpCAM dimer is associated with increased susceptibility towards cleavage by TACE." PeerJ 9 (May 21, 2021): e11484. http://dx.doi.org/10.7717/peerj.11484.
Full textAbstract:
The cell-surface protein EpCAM is a carcinoma marker utilized in diagnostics and prognostics, and a promising therapeutic target. It is involved in nuclear signaling via regulated intramembrane proteolysis (RIP). Many aspects of this process are not fully understood, including the events at the molecular level leading to the exposure of cleavage sites, buried at the dimerization interface. To investigate the effect of dimer stability on cleavage susceptibility we prepared two mutants of human EpCAM ectodomain: a monomeric form, and a disulfide-stabilized dimeric form. We show that the disulfide-stabilized dimer is resistant to tumor necrosis factor-α-converting enzyme (TACE) cleavage, while the monomeric form is more susceptible than the predominantly dimeric wild type. This provides experimental evidence that the oligomeric state of EpCAM is a determinant in RIP and demonstrates the usefulness of the oligomeric state-specific mutants in investigations of EpCAM biological function.