WorldWideScience

Sample records for traction force adhesion

  1. Cellular adhesome screen identifies critical modulators of focal adhesion dynamics, cellular traction forces and cell migration behaviour

    Science.gov (United States)

    Fokkelman, Michiel; Balcıoğlu, Hayri E.; Klip, Janna E.; Yan, Kuan; Verbeek, Fons J.; Danen, Erik H. J.; van de Water, Bob

    2016-01-01

    Cancer cells migrate from the primary tumour into surrounding tissue in order to form metastasis. Cell migration is a highly complex process, which requires continuous remodelling and re-organization of the cytoskeleton and cell-matrix adhesions. Here, we aimed to identify genes controlling aspects of tumour cell migration, including the dynamic organization of cell-matrix adhesions and cellular traction forces. In a siRNA screen targeting most cell adhesion-related genes we identified 200+ genes that regulate size and/or dynamics of cell-matrix adhesions in MCF7 breast cancer cells. In a subsequent secondary screen, the 64 most effective genes were evaluated for growth factor-induced cell migration and validated by tertiary RNAi pool deconvolution experiments. Four validated hits showed significantly enlarged adhesions accompanied by reduced cell migration upon siRNA-mediated knockdown. Furthermore, loss of PPP1R12B, HIPK3 or RAC2 caused cells to exert higher traction forces, as determined by traction force microscopy with elastomeric micropillar post arrays, and led to considerably reduced force turnover. Altogether, we identified genes that co-regulate cell-matrix adhesion dynamics and traction force turnover, thereby modulating overall motility behaviour. PMID:27531518

  2. Prediction of traction forces of motile cells.

    Science.gov (United States)

    Roux, Clément; Duperray, Alain; Laurent, Valérie M; Michel, Richard; Peschetola, Valentina; Verdier, Claude; Étienne, Jocelyn

    2016-10-06

    When crawling on a flat substrate, living cells exert forces on it via adhesive contacts, enabling them to build up tension within their cytoskeleton and to change shape. The measurement of these forces has been made possible by traction force microscopy (TFM), a technique which has allowed us to obtain time-resolved traction force maps during cell migration. This cell 'footprint' is, however, not sufficient to understand the details of the mechanics of migration, that is how cytoskeletal elements (respectively, adhesion complexes) are put under tension and reinforce or deform (respectively, mature and/or unbind) as a result. In a recent paper, we have validated a rheological model of actomyosin linking tension, deformation and myosin activity. Here, we complement this model with tentative models of the mechanics of adhesion and explore how closely these models can predict the traction forces that we recover from experimental measurements during cell migration. The resulting mathematical problem is a PDE set on the experimentally observed domain, which we solve using a finite-element approach. The four parameters of the model can then be adjusted by comparison with experimental results on a single frame of an experiment, and then used to test the predictive power of the model for following frames and other experiments. It is found that the basic pattern of traction forces is robustly predicted by the model and fixed parameters as a function of current geometry only.

  3. Traction forces exerted by epithelial cell sheets

    International Nuclear Information System (INIS)

    Saez, A; Anon, E; Ghibaudo, M; Di Meglio, J-M; Hersen, P; Ladoux, B; Du Roure, O; Silberzan, P; Buguin, A

    2010-01-01

    Whereas the adhesion and migration of individual cells have been well described in terms of physical forces, the mechanics of multicellular assemblies is still poorly understood. Here, we study the behavior of epithelial cells cultured on microfabricated substrates designed to measure cell-to-substrate interactions. These substrates are covered by a dense array of flexible micropillars whose deflection enables us to measure traction forces. They are obtained by lithography and soft replica molding. The pillar deflection is measured by video microscopy and images are analyzed with home-made multiple particle tracking software. First, we have characterized the temporal and spatial distributions of traction forces of cellular assemblies of various sizes. The mechanical force balance within epithelial cell sheets shows that the forces exerted by neighboring cells strongly depend on their relative position in the monolayer: the largest deformations are always localized at the edge of the islands of cells in the active areas of cell protrusions. The average traction stress rapidly decreases from its maximum value at the edge but remains much larger than the inherent noise due to the force resolution of our pillar tracking software, indicating an important mechanical activity inside epithelial cell islands. Moreover, these traction forces vary linearly with the rigidity of the substrate over about two decades, suggesting that cells exert a given amount of deformation rather than a force. Finally, we engineer micropatterned substrates supporting pillars with anisotropic stiffness. On such substrates cellular growth is aligned with respect to the stiffest direction in correlation with the magnitude of the applied traction forces.

  4. Observer Based Traction/Braking Control Design for High Speed Trains Considering Adhesion Nonlinearity

    OpenAIRE

    Cai, Wenchuan; Liao, Wenhao; Li, Danyong; Song, Yongduan

    2014-01-01

    Train traction/braking control, one of the key enabling technologies for automatic train operation, literally takes its action through adhesion force. However, adhesion coefficient of high speed train (HST) is uncertain in general because it varies with wheel-rail surface condition and running speed; thus, it is extremely difficult to be measured, which makes traction/braking control design and implementation of HSTs greatly challenging. In this work, force observers are applied to estimate t...

  5. Observer Based Traction/Braking Control Design for High Speed Trains Considering Adhesion Nonlinearity

    Directory of Open Access Journals (Sweden)

    Wenchuan Cai

    2014-01-01

    Full Text Available Train traction/braking control, one of the key enabling technologies for automatic train operation, literally takes its action through adhesion force. However, adhesion coefficient of high speed train (HST is uncertain in general because it varies with wheel-rail surface condition and running speed; thus, it is extremely difficult to be measured, which makes traction/braking control design and implementation of HSTs greatly challenging. In this work, force observers are applied to estimate the adhesion force or/and the resistance, based on which simple traction/braking control schemes are established under the consideration of actual wheel-rail adhesion condition. It is shown that the proposed controllers have simple structure and can be easily implemented from real applications. Numerical simulation also validates the effectiveness of the proposed control scheme.

  6. 3D Viscoelastic Traction Force Microscopy

    Science.gov (United States)

    Toyjanova, Jennet; Hannen, Erin; Bar-Kochba, Eyal; Darling, Eric M.; Henann, David L.; Franck, Christian

    2014-01-01

    Native cell-material interactions occur on materials differing in their structural composition, chemistry, and physical compliance. While the last two decades have shown the importance of traction forces during cell-material interactions, they have been almost exclusively presented on purely elastic in-vitro materials. Yet, most bodily tissue materials exhibit some level of viscoelasticity, which could play an important role in how cells sense and transduce tractions. To expand the realm of cell traction measurements and to encompass all materials from elastic to viscoelastic, this paper presents a general, and comprehensive approach for quantifying 3D cell tractions in viscoelastic materials. This methodology includes the experimental characterization of the time-dependent material properties for any viscoelastic material with the subsequent mathematical implementation of the determined material model into a 3D traction force microscopy (3D TFM) framework. Utilizing this new 3D viscoelastic TFM (3D VTFM) approach, we quantify the influence of viscosity on the overall material traction calculations and quantify the error associated with omitting time-dependent material effects, as is the case for all other TFM formulations. We anticipate that the 3D VTFM technique will open up new avenues of cell-material investigations on even more physiologically relevant time-dependent materials including collagen and fibrin gels. PMID:25170569

  7. Capillary network formation from dispersed endothelial cells: Influence of cell traction, cell adhesion, and extracellular matrix rigidity

    Science.gov (United States)

    Ramos, João R. D.; Travasso, Rui; Carvalho, João

    2018-01-01

    The formation of a functional vascular network depends on biological, chemical, and physical processes being extremely well coordinated. Among them, the mechanical properties of the extracellular matrix and cell adhesion are fundamental to achieve a functional network of endothelial cells, able to fully cover a required domain. By the use of a Cellular Potts Model and Finite Element Method it is shown that there exists a range of values of endothelial traction forces, cell-cell adhesion, and matrix rigidities where the network can spontaneously be formed, and its properties are characterized. We obtain the analytical relation that the minimum traction force required for cell network formation must obey. This minimum value for the traction force is approximately independent on the considered cell number and cell-cell adhesion. We quantify how these two parameters influence the morphology of the resulting networks (size and number of meshes).

  8. Visualizing the interior architecture of focal adhesions with high-resolution traction maps.

    Science.gov (United States)

    Morimatsu, Masatoshi; Mekhdjian, Armen H; Chang, Alice C; Tan, Steven J; Dunn, Alexander R

    2015-04-08

    Focal adhesions (FAs) are micron-sized protein assemblies that coordinate cell adhesion, migration, and mechanotransduction. How the many proteins within FAs are organized into force sensing and transmitting structures is poorly understood. We combined fluorescent molecular tension sensors with super-resolution light microscopy to visualize traction forces within FAs with <100 nm spatial resolution. We find that αvβ3 integrin selectively localizes to high force regions. Paxillin, which is not generally considered to play a direct role in force transmission, shows a higher degree of spatial correlation with force than vinculin, talin, or α-actinin, proteins with hypothesized roles as force transducers. These observations suggest that αvβ3 integrin and paxillin may play important roles in mechanotransduction.

  9. Traction force dynamics predict gap formation in activated endothelium

    Energy Technology Data Exchange (ETDEWEB)

    Valent, Erik T.; Nieuw Amerongen, Geerten P. van; Hinsbergh, Victor W.M. van; Hordijk, Peter L., E-mail: p.hordijk@vumc.nl

    2016-09-10

    In many pathological conditions the endothelium becomes activated and dysfunctional, resulting in hyperpermeability and plasma leakage. No specific therapies are available yet to control endothelial barrier function, which is regulated by inter-endothelial junctions and the generation of acto-myosin-based contractile forces in the context of cell-cell and cell-matrix interactions. However, the spatiotemporal distribution and stimulus-induced reorganization of these integral forces remain largely unknown. Traction force microscopy of human endothelial monolayers was used to visualize contractile forces in resting cells and during thrombin-induced hyperpermeability. Simultaneously, information about endothelial monolayer integrity, adherens junctions and cytoskeletal proteins (F-actin) were captured. This revealed a heterogeneous distribution of traction forces, with nuclear areas showing lower and cell-cell junctions higher traction forces than the whole-monolayer average. Moreover, junctional forces were asymmetrically distributed among neighboring cells. Force vector orientation analysis showed a good correlation with the alignment of F-actin and revealed contractile forces in newly formed filopodia and lamellipodia-like protrusions within the monolayer. Finally, unstable areas, showing high force fluctuations within the monolayer were prone to form inter-endothelial gaps upon stimulation with thrombin. To conclude, contractile traction forces are heterogeneously distributed within endothelial monolayers and force instability, rather than force magnitude, predicts the stimulus-induced formation of intercellular gaps. - Highlights: • Endothelial monolayers exert dynamic- and heterogeneous traction forces. • High traction forces correlate with junctional areas and the F-actin cytoskeleton. • Newly formed inter-endothelial gaps are characterized by opposing traction forces. • Force stability is a key feature controlling endothelial permeability.

  10. Traction force dynamics predict gap formation in activated endothelium

    International Nuclear Information System (INIS)

    Valent, Erik T.; Nieuw Amerongen, Geerten P. van; Hinsbergh, Victor W.M. van; Hordijk, Peter L.

    2016-01-01

    In many pathological conditions the endothelium becomes activated and dysfunctional, resulting in hyperpermeability and plasma leakage. No specific therapies are available yet to control endothelial barrier function, which is regulated by inter-endothelial junctions and the generation of acto-myosin-based contractile forces in the context of cell-cell and cell-matrix interactions. However, the spatiotemporal distribution and stimulus-induced reorganization of these integral forces remain largely unknown. Traction force microscopy of human endothelial monolayers was used to visualize contractile forces in resting cells and during thrombin-induced hyperpermeability. Simultaneously, information about endothelial monolayer integrity, adherens junctions and cytoskeletal proteins (F-actin) were captured. This revealed a heterogeneous distribution of traction forces, with nuclear areas showing lower and cell-cell junctions higher traction forces than the whole-monolayer average. Moreover, junctional forces were asymmetrically distributed among neighboring cells. Force vector orientation analysis showed a good correlation with the alignment of F-actin and revealed contractile forces in newly formed filopodia and lamellipodia-like protrusions within the monolayer. Finally, unstable areas, showing high force fluctuations within the monolayer were prone to form inter-endothelial gaps upon stimulation with thrombin. To conclude, contractile traction forces are heterogeneously distributed within endothelial monolayers and force instability, rather than force magnitude, predicts the stimulus-induced formation of intercellular gaps. - Highlights: • Endothelial monolayers exert dynamic- and heterogeneous traction forces. • High traction forces correlate with junctional areas and the F-actin cytoskeleton. • Newly formed inter-endothelial gaps are characterized by opposing traction forces. • Force stability is a key feature controlling endothelial permeability.

  11. Traction force microscopy of engineered cardiac tissues.

    Science.gov (United States)

    Pasqualini, Francesco Silvio; Agarwal, Ashutosh; O'Connor, Blakely Bussie; Liu, Qihan; Sheehy, Sean P; Parker, Kevin Kit

    2018-01-01

    Cardiac tissue development and pathology have been shown to depend sensitively on microenvironmental mechanical factors, such as extracellular matrix stiffness, in both in vivo and in vitro systems. We present a novel quantitative approach to assess cardiac structure and function by extending the classical traction force microscopy technique to tissue-level preparations. Using this system, we investigated the relationship between contractile proficiency and metabolism in neonate rat ventricular myocytes (NRVM) cultured on gels with stiffness mimicking soft immature (1 kPa), normal healthy (13 kPa), and stiff diseased (90 kPa) cardiac microenvironments. We found that tissues engineered on the softest gels generated the least amount of stress and had the smallest work output. Conversely, cardiomyocytes in tissues engineered on healthy- and disease-mimicking gels generated significantly higher stresses, with the maximal contractile work measured in NRVM engineered on gels of normal stiffness. Interestingly, although tissues on soft gels exhibited poor stress generation and work production, their basal metabolic respiration rate was significantly more elevated than in other groups, suggesting a highly ineffective coupling between energy production and contractile work output. Our novel platform can thus be utilized to quantitatively assess the mechanotransduction pathways that initiate tissue-level structural and functional remodeling in response to substrate stiffness.

  12. Model for adhesion clutch explains biphasic relationship between actin flow and traction at the cell leading edge

    Science.gov (United States)

    Craig, Erin M.; Stricker, Jonathan; Gardel, Margaret L.; Mogilner, Alex

    2015-01-01

    Cell motility relies on the continuous reorganization of a dynamic actin-myosin-adhesion network at the leading edge of the cell, in order to generate protrusion at the leading edge and traction between the cell and its external environment. We analyze experimentally measured spatial distributions of actin flow, traction force, myosin density, and adhesion density in control and pharmacologically perturbed epithelial cells in order to develop a mechanical model of the actin-adhesion-myosin self-organization at the leading edge. A model in which the F-actin network is treated as a viscous gel, and adhesion clutch engagement is strengthened by myosin but weakened by actin flow, can explain the measured molecular distributions and correctly predict the spatial distributions of the actin flow and traction stress. We test the model by comparing its predictions with measurements of the actin flow and traction stress in cells with fast and slow actin polymerization rates. The model predicts how the location of the lamellipodium-lamellum boundary depends on the actin viscosity and adhesion strength. The model further predicts that the location of the lamellipodium-lamellum boundary is not very sensitive to the level of myosin contraction. PMID:25969948

  13. Creep force modelling for rail traction vehicles based on the Fastsim algorithm

    Science.gov (United States)

    Spiryagin, Maksym; Polach, Oldrich; Cole, Colin

    2013-11-01

    The evaluation of creep forces is a complex task and their calculation is a time-consuming process for multibody simulation (MBS). A methodology of creep forces modelling at large traction creepages has been proposed by Polach [Creep forces in simulations of traction vehicles running on adhesion limit. Wear. 2005;258:992-1000; Influence of locomotive tractive effort on the forces between wheel and rail. Veh Syst Dyn. 2001(Suppl);35:7-22] adapting his previously published algorithm [Polach O. A fast wheel-rail forces calculation computer code. Veh Syst Dyn. 1999(Suppl);33:728-739]. The most common method for creep force modelling used by software packages for MBS of running dynamics is the Fastsim algorithm by Kalker [A fast algorithm for the simplified theory of rolling contact. Veh Syst Dyn. 1982;11:1-13]. However, the Fastsim code has some limitations which do not allow modelling the creep force - creep characteristic in agreement with measurements for locomotives and other high-power traction vehicles, mainly for large traction creep at low-adhesion conditions. This paper describes a newly developed methodology based on a variable contact flexibility increasing with the ratio of the slip area to the area of adhesion. This variable contact flexibility is introduced in a modification of Kalker's code Fastsim by replacing the constant Kalker's reduction factor, widely used in MBS, by a variable reduction factor together with a slip-velocity-dependent friction coefficient decreasing with increasing global creepage. The proposed methodology is presented in this work and compared with measurements for different locomotives. The modification allows use of the well recognised Fastsim code for simulation of creep forces at large creepages in agreement with measurements without modifying the proven modelling methodology at small creepages.

  14. Model-based traction force microscopy reveals differential tension in cellular actin bundles.

    Science.gov (United States)

    Soiné, Jérôme R D; Brand, Christoph A; Stricker, Jonathan; Oakes, Patrick W; Gardel, Margaret L; Schwarz, Ulrich S

    2015-03-01

    Adherent cells use forces at the cell-substrate interface to sense and respond to the physical properties of their environment. These cell forces can be measured with traction force microscopy which inverts the equations of elasticity theory to calculate them from the deformations of soft polymer substrates. We introduce a new type of traction force microscopy that in contrast to traditional methods uses additional image data for cytoskeleton and adhesion structures and a biophysical model to improve the robustness of the inverse procedure and abolishes the need for regularization. We use this method to demonstrate that ventral stress fibers of U2OS-cells are typically under higher mechanical tension than dorsal stress fibers or transverse arcs.

  15. Quantifying the Traction Force of a Single Cell by Aligned Silicon Nanowire Array

    KAUST Repository

    Li, Zhou

    2009-10-14

    The physical behaviors of stationary cells, such as the morphology, motility, adhesion, anchorage, invasion and metastasis, are likely to be important for governing their biological characteristics. A change in the physical properties of mammalian cells could be an indication of disease. In this paper, we present a silicon-nanowire-array based technique for quantifying the mechanical behavior of single cells representing three distinct groups: normal mammalian cells, benign cells (L929), and malignant cells (HeLa). By culturing the cells on top of NW arrays, the maximum traction forces of two different tumor cells (HeLa, L929) have been measured by quantitatively analyzing the bending of the nanowires. The cancer cell exhibits a larger traction force than the normal cell by ∼20% for a HeLa cell and ∼50% for a L929 cell. The traction forces have been measured for the L929 cells and mechanocytes as a function of culture time. The relationship between cells extending area and their traction force has been investigated. Our study is likely important for studying the mechanical properties of single cells and their migration characteristics, possibly providing a new cellular level diagnostic technique. © 2009 American Chemical Society.

  16. High resolution, large deformation 3D traction force microscopy.

    Directory of Open Access Journals (Sweden)

    Jennet Toyjanova

    Full Text Available Traction Force Microscopy (TFM is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D imaging and traction force analysis (3D TFM have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients.

  17. Rigid two-axis MEMS force plate for measuring cellular traction force

    International Nuclear Information System (INIS)

    Takahashi, Hidetoshi; Jung, Uijin G; Shimoyama, Isao; Kan, Tetsuo; Tsukagoshi, Takuya; Matsumoto, Kiyoshi

    2016-01-01

    Cellular traction force is one of the important factors for understanding cell behaviors, such as spreading, migration and differentiation. Cells are known to change their behavior according to the mechanical stiffness of the environment. However, the measurement of cell traction forces on a rigid environment has remained difficult. This paper reports a micro-electromechanical systems (MEMS) force plate that provides a cellular traction force measurement on a rigid substrate. Both the high force sensitivity and high stiffness of the substrate were obtained using piezoresistive sensing elements. The proposed force plate consists of a 70 µ m  ×  15 µ m  ×  5 µ m base as the substrate for cultivating a bovine aortic smooth muscle cell, and the supporting beams with piezoresistors on the sidewall and the surface were used to measure the forces in both the horizontal and vertical directions. The spring constant and force resolution of the fabricated force plate in the horizontal direction were 0.2 N m −1 and less than 0.05 µ N, respectively. The cell traction force was measured, and the traction force increased by approximately 1 µ N over 30 min. These results demonstrate that the proposed force plate is applicable as an effective traction force measurement. (paper)

  18. Novel characteristics of traction force in biliary self-expandable metallic stents.

    Science.gov (United States)

    Hori, Yasuki; Hayashi, Kazuki; Yoshida, Michihiro; Naitoh, Itaru; Ban, Tesshin; Miyabe, Katsuyuki; Kondo, Hiromu; Nishi, Yuji; Umemura, Shuichiro; Fujita, Yasuaki; Natsume, Makoto; Kato, Akihisa; Ohara, Hirotaka; Joh, Takashi

    2017-05-01

    In recent years, knowledge concerning the mechanical properties of self-expandable metallic stents (SEMS) has increased. In a previous study, we defined traction force and traction momentum and reported that these characteristics are important for optimal stent deployment. However, traction force and traction momentum were represented as relative values and were not evaluated in various conditions. The purpose of the present study was to measure traction force in various situations assumed during SEMS placement. Traction force and traction momentum were measured in non-stricture, stricture, and angled stricture models using in-house equipment. Stricture and angled stricture models had significantly higher traction force and traction momentum than those of the non-stricture model (stricture vs non-stricture: traction force, 7.2 N vs 1.4 N, P stent influenced the traction force. Clinicians should be aware of the transition of the traction force and should schedule X-ray imaging during SEMS placement. © 2017 Japan Gastroenterological Endoscopy Society.

  19. DEFINITION OF LOCOMOTIVE TRACTION FORCE WITH REGARD TO UNEVEN LOADING OF WHEEL-MOTOR BLOCK

    Directory of Open Access Journals (Sweden)

    B. Ye. Bodnar

    2013-11-01

    Full Text Available Purpose. The article describes the most common methods for determining the locomotive traction force. Solving the tasks of traction calculations involves determination of the forces influencing the train at every point of the way. When choosing a rational trajectory of the train motion and the development of operational regulations of train driving it is necessary to determine the actual value of the locomotive traction force. Considering various factors, power value of traction electric motor of locomotive may have significant differences. Advancement of the operational definition system of the locomotive traction force during the calculations by electrical parameters of traction electric motor with regard to uneven load of wheel-motor block is the purpose of the article. Methodology. The method of determining the traction force of locomotives and diesel locomotives with electric transmission, which is based on primary data acquisition of traction electric engines of direct current behavior, was proposed. Sensors and their integration into the electrical circuitry of the locomotive in order to get the data in digital form and for operational calculation of the each traction motor mode and the definition of locomotive traction force are presented. Findings. The experimental investigation of the system of locomotive traction force determination with the electric traction motor ED-105 was offered. A comparison of electrical and mechanical power of the electric motor was conducted. Originality. The system of locomotives power operational definition, which takes into account the variable electro-mechanical factors of wheel and motor blocks and increases the accuracy of the calculations, was proposed. Practical value. The system is a part of an onboard complex in definition of energy-efficient regimes for trains movement and provides the definition of accelerating and decelerating forces.

  20. Local traction force in the proximal leading process triggers nuclear translocation during neuronal migration.

    Science.gov (United States)

    Umeshima, Hiroki; Nomura, Ken-Ichi; Yoshikawa, Shuhei; Hörning, Marcel; Tanaka, Motomu; Sakuma, Shinya; Arai, Fumihito; Kaneko, Makoto; Kengaku, Mineko

    2018-04-05

    Somal translocation in long bipolar neurons is regulated by actomyosin contractile forces, yet the precise spatiotemporal sites of force generation are unknown. Here we investigate the force dynamics generated during somal translocation using traction force microscopy. Neurons with a short leading process generated a traction force in the growth cone and counteracting forces in the leading and trailing processes. In contrast, neurons with a long leading process generated a force dipole with opposing traction forces in the proximal leading process during nuclear translocation. Transient accumulation of actin filaments was observed at the dipole center of the two opposing forces, which was abolished by inhibition of myosin II activity. A swelling in the leading process emerged and generated a traction force that pulled the nucleus when nuclear translocation was physically hampered. The traction force in the leading process swelling was uncoupled from somal translocation in neurons expressing a dominant negative mutant of the KASH protein, which disrupts the interaction between cytoskeletal components and the nuclear envelope. Our results suggest that the leading process is the site of generation of actomyosin-dependent traction force in long bipolar neurons, and that the traction force is transmitted to the nucleus via KASH proteins. Copyright © 2018 Elsevier B.V. and Japan Neuroscience Society. All rights reserved.

  1. Nano-mechanics of Tunable Adhesion using Non Covalent Forces

    Energy Technology Data Exchange (ETDEWEB)

    Kenneth Liechti

    2012-09-08

    The objective of this program was to examine, via experiment and atomistic and continuum analysis, coordinated noncovalent bonding over a range of length scales with a view to obtaining modulated, patterned and reversible bonding at the molecular level. The first step in this project was to develop processes for depositing self-assembled monolayers (SAMs) bearing carboxylic acid and amine moieties on Si (111) surfaces and probe tips of an interfacial force microscope (IFM). This allowed the adhesive portion of the interactions between functionalized surfaces to be fully captured in the force-displacement response (force profiles) that are measured by the IFM. The interactionswere extracted in the form of traction-separation laws using combined molecular and continuum stress analyses. In this approach, the results of molecular dynamics analyses of SAMs subjected to simple stress states are used to inform continuum models of their stress-strain behavior. Continuum analyses of the IFM experiment were then conducted, which incorporate the stress-strain behavior of the SAMs and traction-separation relations that represent the interactions between the tip and functionalized Si surface. Agreement between predicted and measured force profiles was taken to imply that the traction-separation relations have been properly extracted. Scale up to larger contact areas was considered by forming Si/SAM/Si sandwiches and then separating them via fracture experiments. The mode 1 traction-separation relations have been extracted using fracture mechanics concepts under mode 1 and mixed-mode conditions. Interesting differences were noted between the three sets of traction-separation relations.

  2. Application on forced traction test in surgeries for orbital blowout fracture

    Directory of Open Access Journals (Sweden)

    Bao-Hong Han

    2014-05-01

    Full Text Available AIM: To discuss the application of forced traction test in surgeries for orbital blowout fracture.METHODS: The clinical data of 28 patients with reconstructive surgeries for orbital fracture were retrospectively analyzed. All patients were treated with forced traction test before/in/after operation. The eyeball movement and diplopia were examined and recorded pre-operation, 3 and 6mo after operation, respectively.RESULTS: Diplopia was improved in all 28 cases with forced traction test. There was significant difference between preoperative and post-operative diplopia at 3 and 6mo(PCONCLUSION: Forced traction test not only have a certain clinical significance in diagnosis of orbital blowout fracture, it is also an effective method in improving diplopia before/in/after operation.

  3. Measurement of the traction force of biological cells by digital holography

    Science.gov (United States)

    Yu, Xiao; Cross, Michael; Liu, Changgeng; Clark, David C.; Haynie, Donald T.; Kim, Myung K.

    2011-01-01

    The traction force produced by biological cells has been visualized as distortions in flexible substrata. We have utilized quantitative phase microscopy by digital holography (DH-QPM) to study the wrinkling of a silicone rubber film by motile fibroblasts. Surface deformation and the cellular traction force have been measured from phase profiles in a direct and straightforward manner. DH-QPM is shown to provide highly efficient and versatile means for quantitatively analyzing cellular motility. PMID:22254175

  4. IMPLEMENTATION MODEL OF MOTOR TRACTION FORCE OF MAGLEV TRAIN

    Directory of Open Access Journals (Sweden)

    V. O. Polyakov

    2016-08-01

    Full Text Available Purpose. Traction force implementation (TFI by the motor of magnetic levitation train (MLT occurs in the process of electric-to-kinetic energy transformation at interaction of inductor and armature magnetic fields. Ac-cordingly, the aim of this study is to obtain a correct description of such energy transformation. Methodology. At the present stage, a mathematical and, in particular, computer simulation is the main and most universal tool for analysis and synthesis of processes and systems. At the same time, radical advantages of this tool make the precision of selection of a particular research methodology even more important. It is especially important for such a large and complex system as MLT. Therefore the special attention in the work is given to the rationale for choosing the research paradigm selective features. Findings. The analysis results of existing TFI process model versions indicate that each of them has both advantages and disadvantages. Therefore, one of the main results of this study was the creation of a mathematical model for such process that would preserve the advantages of previous versions, but would be free from their disadvantages. The work provides rationale for application (for the purposes of research of train motor TFI of the integrative holistic paradigm, which assimilates the advantages of the theory of electric circuit and magnetic field. Originality. The priority of creation of such paradigm and corresponding version of FI model constitute the originality of the research. Practical value. The main manifestation of practical value of this research in the opportunity, in case of use of its results, for significant increase in efficiency of MLT dynamic studies, on the condition that their generalized costs will not rise.

  5. Tracking Traction Force Changes of Single Cells on the Liquid Crystal Surface

    Directory of Open Access Journals (Sweden)

    Chin Fhong Soon

    2015-01-01

    Full Text Available Cell migration is a key contributor to wound repair. This study presents findings indicating that the liquid crystal based cell traction force transducer (LCTFT system can be used in conjunction with a bespoke cell traction force mapping (CTFM software to monitor cell/surface traction forces from quiescent state in real time. In this study, time-lapse photo microscopy allowed cell induced deformations in liquid crystal coated substrates to be monitored and analyzed. The results indicated that the system could be used to monitor the generation of cell/surface forces in an initially quiescent cell, as it migrated over the culture substrate, via multiple points of contact between the cell and the surface. Future application of this system is the real-time assaying of the pharmacological effects of cytokines on the mechanics of cell migration.

  6. Optimal arm posture control and tendon traction forces of a coupled tendon-driven manipulator

    International Nuclear Information System (INIS)

    Ma, Shugen

    1997-01-01

    In this study, the optimum arm posture of a coupled tendon-driven multijoint manipulator arm (or CT Arm) at maximum payload output was derived and the corresponding tendon traction forces were also analyzed, during management of a heavy payload by the manipulator in a gravity environment. The CT Arm is special tendon traction transmission mechanism in which a pair of tendons used to drive a joint is pulled from base actuators via pulleys mounted on the base-side joints. This mechanism enables optimal utilization of the coupled drive function of tendon traction forces and thus enables the lightweight manipulator to exhibit large payload capability. The properties of the CT Arm mechanism are elucidated by the proposed optimal posture control scheme. Computer simulation was also executed to verify the validity of the proposed control scheme. (author)

  7. Microparticle adhesion studies by atomic force microscopy

    NARCIS (Netherlands)

    Segeren, L.H.G.J.; Siebum, B.; Karssenberg, F.G.; Berg, van den J.W.A.; Vancso, G.J.

    2002-01-01

    Atomic force microscopy (AFM) is one of the most flexible and simple techniques for probing surface interactions. This article reviews AFM studies on particle adhesion. Special attention is paid to the characterization of roughness and its effect on adhesion. This is of importance when comparing the

  8. Adhesion force imaging in air and liquid by adhesion mode atomic force microscopy

    NARCIS (Netherlands)

    van der Werf, Kees; Putman, C.A.J.; Putman, Constant A.; de Grooth, B.G.; Greve, Jan

    1994-01-01

    A new imaging mode for the atomic force microscope(AFM), yielding images mapping the adhesion force between tip and sample, is introduced. The adhesion mode AFM takes a force curve at each pixel by ramping a piezoactuator, moving the silicon‐nitride tip up and down towards the sample. During the

  9. Finger-Shaped GelForce: Sensor for Measuring Surface Traction Fields for Robotic Hand.

    Science.gov (United States)

    Sato, K; Kamiyama, K; Kawakami, N; Tachi, S

    2010-01-01

    It is believed that the use of haptic sensors to measure the magnitude, direction, and distribution of a force will enable a robotic hand to perform dexterous operations. Therefore, we develop a new type of finger-shaped haptic sensor using GelForce technology. GelForce is a vision-based sensor that can be used to measure the distribution of force vectors, or surface traction fields. The simple structure of the GelForce enables us to develop a compact finger-shaped GelForce for the robotic hand. GelForce that is developed on the basis of an elastic theory can be used to calculate surface traction fields using a conversion equation. However, this conversion equation cannot be analytically solved when the elastic body of the sensor has a complicated shape such as the shape of a finger. Therefore, we propose an observational method and construct a prototype of the finger-shaped GelForce. By using this prototype, we evaluate the basic performance of the finger-shaped GelForce. Then, we conduct a field test by performing grasping operations using a robotic hand. The results of this test show that using the observational method, the finger-shaped GelForce can be successfully used in a robotic hand.

  10. Adhesive forces at bimetallic interfaces

    International Nuclear Information System (INIS)

    Das, M.P.; Nafari, N.; Ziesche, P.; Kaschner, H.R.

    1987-03-01

    Force concepts in condensed systems have progressed significantly in recent years. In the context of bimetallic interfaces we consider the Pauli-Hellman-Feynman theorem, use it to check the variational calculations of interfacial energies and estimate the force constants. (author). 13 refs, 2 figs, 2 tabs

  11. Calculation of locomotive traction force in transient rolling contact

    Directory of Open Access Journals (Sweden)

    Voltr P.

    2017-06-01

    Full Text Available To represent thewheel-rail contact in numerical simulations of rail vehicles, simplified models (Fastsim, Pola´ch etc. are usually employed. These models are designed for steady rolling only, which is perfectly suitable in many cases. However, it is shown to be limiting for simulations at very low vehicle speeds, and therefore it does not actually allow simulation of vehicle running at arbitrarily variable speed. The simplified model of transient rolling, which involves calculation of the stress distribution in the discretised contact area, overcomes this disadvantage but might be unnecessarily complex for more simple simulations. In this paper, an approximative creep force computation method for transient rolling is presented. Its purpose is not to study the transient phenomena themselves but provide a simple and readily available way to prevent incorrect results of the numerical simulation when the vehicle speed approaches zero. The proper function of the proposed method is demonstrated by a simulation of start-up and interrupted sliding of a four-axle locomotive.

  12. Direct observation of CD4 T cell morphologies and their cross-sectional traction force derivation on quartz nanopillar substrates using focused ion beam technique

    Science.gov (United States)

    Kim, Dong-Joo; Kim, Gil-Sung; Hyung, Jung-Hwan; Lee, Won-Yong; Hong, Chang-Hee; Lee, Sang-Kwon

    2013-07-01

    Direct observations of the primary mouse CD4 T cell morphologies, e.g., cell adhesion and cell spreading by culturing CD4 T cells in a short period of incubation (e.g., 20 min) on streptavidin-functionalized quartz nanopillar arrays (QNPA) using a high-content scanning electron microscopy method were reported. Furthermore, we first demonstrated cross-sectional cell traction force distribution of surface-bound CD4 T cells on QNPA substrates by culturing the cells on top of the QNPA and further analysis in deflection of underlying QNPA via focused ion beam-assisted technique.

  13. An adhesive contact mechanics formulation based on atomistically induced surface traction

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Houfu [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Ren, Bo [Livermore Software Technology Corporation, 7374 Las Positas Road, Livermore, CA 94551 (United States); Li, Shaofan, E-mail: shaofan@berkeley.edu [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2015-12-01

    In this work, we have developed a novel multiscale computational contact formulation based on the generalized Derjuguin approximation for continua that are characterized by atomistically enriched constitutive relations in order to study macroscopic interaction between arbitrarily shaped deformable continua. The proposed adhesive contact formulation makes use of the microscopic interaction forces between individual particles in the interacting bodies. In particular, the double-layer volume integral describing the contact interaction (energy, force vector, matrix) is converted into a double-layer surface integral through a mathematically consistent approach that employs the divergence theorem and a special partitioning technique. The proposed contact model is formulated in the nonlinear continuum mechanics framework and implemented using the standard finite element method. With no large penalty constant, the stiffness matrix of the system will in general be well-conditioned, which is of great significance for quasi-static analysis. Three numerical examples are presented to illustrate the capability of the proposed method. Results indicate that with the same mesh configuration, the finite element computation based on the surface integral approach is faster and more accurate than the volume integral based approach. In addition, the proposed approach is energy preserving even in a very long dynamic simulation.

  14. High-Force Versus Low-Force Lumbar Traction in Acute Lumbar Sciatica Due to Disc Herniation: A Preliminary Randomized Trial.

    Science.gov (United States)

    Isner-Horobeti, Marie-Eve; Dufour, Stéphane Pascal; Schaeffer, Michael; Sauleau, Erik; Vautravers, Philippe; Lecocq, Jehan; Dupeyron, Arnaud

    This study compared the effects of high-force versus low-force lumbar traction in the treatment of acute lumbar sciatica secondary to disc herniation. A randomized double blind trial was performed, and 17 subjects with acute lumbar sciatica secondary to disc herniation were assigned to high-force traction at 50% body weight (BW; LT50, n = 8) or low force traction at 10% BW (LT10, n = 9) for 10 sessions in 2 weeks. Radicular pain (visual analogue scale [VAS]), lumbo-pelvic-hip complex motion (finger-to-toe test), lumbar-spine mobility (Schöber-Macrae test), nerve root compression (straight-leg-raising test), disability (EIFEL score), drug consumption, and overall evaluation of each patient were measured at days 0, 7, 1, 4, and 28. Significant (P sciatica secondary to disc herniation who received 2 weeks of lumbar traction reported reduced radicular pain and functional impairment and improved well-being regardless of the traction force group to which they were assigned. The effects of the traction treatment were independent of the initial level of medication and appeared to be maintained at the 2-week follow-up. Copyright © 2016. Published by Elsevier Inc.

  15. Local adhesive surface properties studied by force microscopy

    International Nuclear Information System (INIS)

    Lekka, M.; Lekki, J.; Marszalek, M.; Stachura, Z.; Cleff, B.

    1998-01-01

    Scanning force microscopy was used in the contact mode to determine the adhesion force between a mica surface and a silicon nitride tip. The measurements were performed in an aqueous solution of sodium and calcium chlorides. The adhesion force according to the Derjaguin-Landau-Verwey-Overbeek theory depends on the competition between two kinds of forces: van der Waals and electrostatic 'double layer'. Two different curves of adhesion force versus salt concentration were obtained from the experiment with monovalent and divalent ions. The tip-surface adhesion force was determined from a statistical analysis of data obtained from the force vs. distance retracting curves. (author)

  16. Design rules for biomolecular adhesion: lessons from force measurements.

    Science.gov (United States)

    Leckband, Deborah

    2010-01-01

    Cell adhesion to matrix, other cells, or pathogens plays a pivotal role in many processes in biomolecular engineering. Early macroscopic methods of quantifying adhesion led to the development of quantitative models of cell adhesion and migration. The more recent use of sensitive probes to quantify the forces that alter or manipulate adhesion proteins has revealed much greater functional diversity than was apparent from population average measurements of cell adhesion. This review highlights theoretical and experimental methods that identified force-dependent molecular properties that are central to the biological activity of adhesion proteins. Experimental and theoretical methods emphasized in this review include the surface force apparatus, atomic force microscopy, and vesicle-based probes. Specific examples given illustrate how these tools have revealed unique properties of adhesion proteins and their structural origins.

  17. Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements

    Science.gov (United States)

    Tong, Ming Hui; Huang, Nan; Zhang, Wei; Zhou, Zhuo Long; Ngan, Alfonso Hing Wan; Du, Yanan; Chan, Barbara Pui

    2016-01-01

    Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively.

  18. Micropillar displacements by cell traction forces are mechanically correlated with nuclear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qingsen; Makhija, Ekta; Hameed, F.M. [Mechanobiology Institute, National University of Singapore (Singapore); Shivashankar, G.V., E-mail: shiva.gvs@gmail.com [Mechanobiology Institute, National University of Singapore (Singapore); Department of Biological Sciences, National University of Singapore (Singapore)

    2015-05-29

    Cells sense physical cues at the level of focal adhesions and transduce them to the nucleus by biochemical and mechanical pathways. While the molecular intermediates in the mechanical links have been well studied, their dynamic coupling is poorly understood. In this study, fibroblast cells were adhered to micropillar arrays to probe correlations in the physical coupling between focal adhesions and nucleus. For this, we used novel imaging setup to simultaneously visualize micropillar deflections and EGFP labeled chromatin structure at high spatial and temporal resolution. We observed that micropillar deflections, depending on their relative positions, were positively or negatively correlated to nuclear and heterochromatin movements. Our results measuring the time scales between micropillar deflections and nucleus centroid displacement are suggestive of a strong elastic coupling that mediates differential force transmission to the nucleus. - Highlights: • Correlation between focal adhesions and nucleus studied using novel imaging setup. • Micropillar and nuclear displacements were measured at high resolution. • Correlation timescales show strong elastic coupling between cell edge and nucleus.

  19. The Role of the Electrostatic Force in Spore Adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Eunhyea [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Lee, Ida [University of Tennessee, Knoxville (UTK); Tsouris, Costas [ORNL

    2010-01-01

    Electrostatic force is investigated as one of the components of the adhesion force between Bacillus thuringiensis (Bt) spores and planar surfaces. The surface potentials of a Bt spore and a mica surface are experimentally obtained using a combined atomic force microscopy (AFM)-scanning surface potential microscopy technique. On the basis of experimental information, the surface charge density of the spores is estimated at 0.03 {micro}C/cm{sup 2} at 20% relative humidity and decreases with increasing humidity. The Coulombic force is introduced for the spore-mica system (both charged, nonconductive surfaces), and an electrostatic image force is introduced to the spore-gold system because gold is electrically conductive. The Coulombic force for spore-mica is repulsive because the components are similarly charged, while the image force for the spore-gold system is attractive. The magnitude of both forces decreases with increasing humidity. The electrostatic forces are added to other force components, e.g., van der Waals and capillary forces, to obtain the adhesion force for each system. The adhesion forces measured by AFM are compared to the estimated values. It is shown that the electrostatic (Coulombic and image) forces play a significant role in the adhesion force between spores and planar surfaces.

  20. A novel assessment of the traction forces upon settlement of two typical marine fouling invertebrates using PDMS micropost arrays

    Directory of Open Access Journals (Sweden)

    Kang Xiao

    2018-01-01

    Full Text Available Marine biofouling poses a severe threat to maritime and aquaculture industries. To prevent the attachment of marine biofouling organisms on man-made structures, countless cost and effort was spent annually. In particular, most attention has been paid on the development of efficient and environmentally friendly fouling-resistant coatings, as well as larval settlement mechanism of several major biofouling invertebrates. In this study, polydimethylsiloxane (PDMS micropost arrays were utilized as the settlement substrata and opposite tractions were identified during early settlement of the barnacle Amphibalanus amphitrite and the bryozoan Bugula neritina. The settling A. amphitrite pushed the periphery microposts with an average traction force of 376.2 nN, while settling B. neritina pulled the periphery microposts with an average traction force of 205.9 nN. These micropost displacements are consistent with the body expansion of A. amphitrite during early post-settlement metamorphosis stage and elevation of wall epithelium of B. neritina during early pre-ancestrula stage, respectively. As such, the usage of micropost array may supplement the traditional histological approach to indicate the early settlement stages or even the initiation of larval settlement of marine fouling organisms, and could finally aid in the development of automatic monitoring platform for the real-time analysis on this complex biological process.

  1. Single-cell force spectroscopy of pili-mediated adhesion

    Science.gov (United States)

    Sullan, Ruby May A.; Beaussart, Audrey; Tripathi, Prachi; Derclaye, Sylvie; El-Kirat-Chatel, Sofiane; Li, James K.; Schneider, Yves-Jacques; Vanderleyden, Jos; Lebeer, Sarah; Dufrêne, Yves F.

    2013-12-01

    Although bacterial pili are known to mediate cell adhesion to a variety of substrates, the molecular interactions behind this process are poorly understood. We report the direct measurement of the forces guiding pili-mediated adhesion, focusing on the medically important probiotic bacterium Lactobacillus rhamnosus GG (LGG). Using non-invasive single-cell force spectroscopy (SCFS), we quantify the adhesion forces between individual bacteria and biotic (mucin, intestinal cells) or abiotic (hydrophobic monolayers) surfaces. On hydrophobic surfaces, bacterial pili strengthen adhesion through remarkable nanospring properties, which - presumably - enable the bacteria to resist high shear forces under physiological conditions. On mucin, nanosprings are more frequent and adhesion forces larger, reflecting the influence of specific pili-mucin bonds. Interestingly, these mechanical responses are no longer observed on human intestinal Caco-2 cells. Rather, force curves exhibit constant force plateaus with extended ruptures reflecting the extraction of membrane nanotethers. These single-cell analyses provide novel insights into the molecular mechanisms by which piliated bacteria colonize surfaces (nanosprings, nanotethers), and offer exciting avenues in nanomedicine for understanding and controlling the adhesion of microbial cells (probiotics, pathogens).

  2. Adhesion force of staphylococcus aureus on various biomaterial surfaces.

    Science.gov (United States)

    Alam, Fahad; Balani, Kantesh

    2017-01-01

    Staphylococcus comprises of more than half of all pathogens in orthopedic implant infections and they can cause major bone infection which can result in destruction of joint and bone. In the current study, adhesion force of bacteria on the surface of various biomaterial surfaces is measured using atomic force microscope (AFM). Staphylococcus aureus was immobilized on an AFM tipless cantilever as a force probe to measure the adhesion force between bacteria and biomaterials (viz. ultra-high molecular weight poly ethylene (UHMWPE), stainless steel (SS), Ti-6Al-4V alloy, hydroxyapatite (HA)). At the contact time of 10s, UHMWPE shows weak adhesion force (~4nN) whereas SS showed strong adhesion force (~15nN) due to their surface energy and surface roughness. Bacterial retention and viability experiment (3M™ petrifilm test, agar plate) dictates that hydroxyapatite shows the lowest vaibility of bacteria, whereas lowest bacterial retention is observed on UHMWPE surface. Similar results were obtained from live/dead staining test, where HA shows 65% viability, whereas on UHMWPE, SS and Ti-6Al-4V, the bacterial viability is 78%, 94% and 97%, respectively. Lower adhesion forces, constrained pull-off distance (of bacterial) and high antibacterial resistance of bioactive-HA makes it a potential biomaterial for bone-replacement arthroplasty. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Development And Use Of Advanced Microfabricated Traction Force Sensing Substrates To Study The Effect of Nanosilver On Human Macrophages

    Science.gov (United States)

    Stark, Daniel Thomas

    While nanoparticles are a natural byproduct of combustion and a number of natural processes, engineered nanoparticles have only recently entered the consumer market. This motivates the development of methods for studying their effects on human cells, thereby indicating how larger models such as animals and humans might react to them. This research develops a method to mechanically characterize cellular traction forces as a measure of exposure to nanoparticles. To do this, 1microm micropillar molds were fabricated in silicon wafers using smooth sidewall reactive ion plasma etching technologies. Polydimethylsiloxane (PDMS), was cured inside the silicon molds, subsequently treated for cell culture and used to measure cellular traction forces over time in live cell time-lapse experiments. For the first time, transmitted light was used to visualize the PDMS micropillars; a force resolution of 5.6 +/-2.1nN was achieved across all experiments using a standard Olympus IX81 confocal microscope affixed with a 60x NA2.1 objective. To initiate cellular movement, monocyte chemoattractant protein (MCP-1) was conjugated to 1microm latex beads. The effects of 40nm silver nanoparticle exposures were quantified using the micropillar array. Changes in cellular behavior between the control group and cells exposed to nanosilver were not significant, although a comparison between the 5microg/ml and 10microg/ml nanosilver concentrations yielded strong significance using a 2 sided Students t test.

  4. Determination of adhesion forces between smooth and structured solids

    International Nuclear Information System (INIS)

    Fischer, Hartmut R.; Gelinck, Edwin R.M.

    2012-01-01

    Highlights: ► Extension of know data with respect to decency of adhesion from probe radius to 8 decades. ► Use of large interaction surface areas for precision measurement of adhesion forces. ► Deliberated increase of roughness as tool to tune adhesion forces and to suppress spontaneous adhesion. - Abstract: Surfaces tend to be made smoother in order to gain flatness or in order to fulfill the need for more precise and reproducible positioning of parts. Adhesion or even sticking of the surfaces is a major showstopper for these applications. There are several measures that can be taken in order to reduce spontaneous adhesion. Quantification of the effectiveness of the chosen solution is most often done using an atomic force microscope (AFM) with probes varying from 1 nm to 8 μm of contact diameter. A serious disadvantage in measuring adhesion by sharp tips is the wear of the tips. Sharp tips wear easily, resulting in undefined contact areas. When the real area of contact is not well defined, the quantification of the adhesion force is not significant. In the current study results of AFM measurements from literature with different tip diameters of colloidal probes are compared with AFM cantilevers with a plateau tip and using probes from large spheres using an alternative setup in combination with a Universal Nano-mechanical Analyzer (UNAT). Test results are shown. Another part of the study deals with a deliberately roughening of smooth surfaces to minimize (spontaneous) adhesion. Good agreement has been found with existing results.

  5. Toward single cell traction microscopy within 3D collagen matrices

    International Nuclear Information System (INIS)

    Hall, Matthew S.; Long, Rong; Feng, Xinzeng; Huang, YuLing; Hui, Chung-Yuen; Wu, Mingming

    2013-01-01

    Mechanical interaction between the cell and its extracellular matrix (ECM) regulates cellular behaviors, including proliferation, differentiation, adhesion, and migration. Cells require the three-dimensional (3D) architectural support of the ECM to perform physiologically realistic functions. However, current understanding of cell–ECM and cell–cell mechanical interactions is largely derived from 2D cell traction force microscopy, in which cells are cultured on a flat substrate. 3D cell traction microscopy is emerging for mapping traction fields of single animal cells embedded in either synthetic or natively derived fibrous gels. We discuss here the development of 3D cell traction microscopy, its current limitations, and perspectives on the future of this technology. Emphasis is placed on strategies for applying 3D cell traction microscopy to individual tumor cell migration within collagen gels. - Highlights: • Review of the current state of the art in 3D cell traction force microscopy. • Bulk and micro-characterization of remodelable fibrous collagen gels. • Strategies for performing 3D cell traction microscopy within collagen gels

  6. Toward single cell traction microscopy within 3D collagen matrices

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Matthew S. [Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853 (United States); Long, Rong [Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada T6G 2G8 (Canada); Feng, Xinzeng [Department of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853 (United States); Huang, YuLing [Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853 (United States); Hui, Chung-Yuen [Department of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853 (United States); Wu, Mingming, E-mail: mw272@cornell.edu [Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853 (United States)

    2013-10-01

    Mechanical interaction between the cell and its extracellular matrix (ECM) regulates cellular behaviors, including proliferation, differentiation, adhesion, and migration. Cells require the three-dimensional (3D) architectural support of the ECM to perform physiologically realistic functions. However, current understanding of cell–ECM and cell–cell mechanical interactions is largely derived from 2D cell traction force microscopy, in which cells are cultured on a flat substrate. 3D cell traction microscopy is emerging for mapping traction fields of single animal cells embedded in either synthetic or natively derived fibrous gels. We discuss here the development of 3D cell traction microscopy, its current limitations, and perspectives on the future of this technology. Emphasis is placed on strategies for applying 3D cell traction microscopy to individual tumor cell migration within collagen gels. - Highlights: • Review of the current state of the art in 3D cell traction force microscopy. • Bulk and micro-characterization of remodelable fibrous collagen gels. • Strategies for performing 3D cell traction microscopy within collagen gels.

  7. Young adult patient with two palatally maxillary impacted canines and forced traction on rigid arches of stabilization. Case report.

    Science.gov (United States)

    Mucedero, M; Pezzuto, C; Rozzi, M; Ricchiuti, M R; Cozza, P

    2016-01-01

    Young adult patient treated for impaction of two maxillary canines. C.S., 15 years, female. Diagnostic evaluation by clinical and radiographic examinations shows permanent dentition with persistence of 5.3 and 6.3, impaction of 1.3 and 2.3, dento-skeletal Cl I malocclusion, normodivergence of bone bases. Analysis of TC dentalscan confirms the palatal impaction of 1.3 and 2.3. The treatment plan provided an orthodontic-surgical approach for adequate space management in dental arch, evaluation of eruption movements, choice of anchorage device, surgical exposure and application of the brackets. Deciduous canines have been extracted and an edgewise appliance with rigid rectangular full thickness archwires has been used to align the arches and to obtain maximum anchorage during the forced traction. The surgical phase, for exposure of 1.3 and 2.3 respectively, performed an open technique by excisional uncovering and a close technique by a repositioned flap. The case has been finalized for the achievement of the right occlusal keys. The possibility to choose the surgical technique depending on the intraosseous position of impacted teeth in association to the edgewise therapy with full thickness arches allows to realize an effectiveness surgical-orthodontic approach for the forced traction of impacted teeth in a favourable position.

  8. Adhesion forces and coaggregation between vaginal staphylococci and lactobacilli.

    Directory of Open Access Journals (Sweden)

    Jessica A Younes

    Full Text Available Urogenital infections are the most common ailments afflicting women. They are treated with dated antimicrobials whose efficacy is diminishing. The process of infection involves pathogen adhesion and displacement of indigenous Lactobacillus crispatus and Lactobacillus jensenii. An alternative therapeutic approach to antimicrobial therapy is to reestablish lactobacilli in this microbiome through probiotic administration. We hypothesized that lactobacilli displaying strong adhesion forces with pathogens would facilitate coaggregation between the two strains, ultimately explaining the elimination of pathogens seen in vivo. Using atomic force microscopy, we found that adhesion forces between lactobacilli and three virulent toxic shock syndrome toxin 1-producing Staphylococcus aureus strains, were significantly stronger (2.2-6.4 nN than between staphylococcal pairs (2.2-3.4 nN, especially for the probiotic Lactobacillus reuteri RC-14 (4.0-6.4 nN after 120 s of bond-strengthening. Moreover, stronger adhesion forces resulted in significantly larger coaggregates. Adhesion between the bacteria occurred instantly upon contact and matured within one to two minutes, demonstrating the potential for rapid anti-pathogen effects using a probiotic. Coaggregation is one of the recognized mechanisms through which lactobacilli can exert their probiotic effects to create a hostile micro-environment around a pathogen. With antimicrobial options fading, it therewith becomes increasingly important to identify lactobacilli that bind strongly with pathogens.

  9. Quantifying the Traction Force of a Single Cell by Aligned Silicon Nanowire Array

    KAUST Repository

    Li, Zhou; Song, Jinhui; Mantini, Giulia; Lu, Ming-Yen; Fang, Hao; Falconi, Christian; Chen, Lih-Juann; Wang, Zhong Lin

    2009-01-01

    The physical behaviors of stationary cells, such as the morphology, motility, adhesion, anchorage, invasion and metastasis, are likely to be important for governing their biological characteristics. A change in the physical properties of mammalian

  10. Traction cytometry: regularization in the Fourier approach and comparisons with finite element method.

    Science.gov (United States)

    Kulkarni, Ankur H; Ghosh, Prasenjit; Seetharaman, Ashwin; Kondaiah, Paturu; Gundiah, Namrata

    2018-05-09

    Traction forces exerted by adherent cells are quantified using displacements of embedded markers on polyacrylamide substrates due to cell contractility. Fourier Transform Traction Cytometry (FTTC) is widely used to calculate tractions but has inherent limitations due to errors in the displacement fields; these are mitigated through a regularization parameter (γ) in the Reg-FTTC method. An alternate finite element (FE) approach computes tractions on a domain using known boundary conditions. Robust verification and recovery studies are lacking but essential in assessing the accuracy and noise sensitivity of the traction solutions from the different methods. We implemented the L2 regularization method and defined a maximum curvature point in the traction with γ plot as the optimal regularization parameter (γ*) in the Reg-FTTC approach. Traction reconstructions using γ* yield accurate values of low and maximum tractions (Tmax) in the presence of up to 5% noise. Reg-FTTC is hence a clear improvement over the FTTC method but is inadequate to reconstruct low stresses such as those at nascent focal adhesions. FE, implemented using a node-by-node comparison, showed an intermediate reconstruction compared to Reg-FTTC. We performed experiments using mouse embryonic fibroblast (MEF) and compared results between these approaches. Tractions from FTTC and FE showed differences of ∼92% and 22% as compared to Reg-FTTC. Selection of an optimum value of γ for each cell reduced variability in the computed tractions as compared to using a single value of γ for all the MEF cells in this study.

  11. Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Boks, N.P.; Norde, W.; Meil, H.C.; Busscher, H.J.

    2008-01-01

    Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F-prev) and to detach adhering bacteria (F-det) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the

  12. Quantification of Staphylococcus aureus adhesion forces on various dental restorative materials using atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Merghni, Abderrahmen, E-mail: abderrahmen_merghni@yahoo.fr [Laboratoire des Maladies Transmissibles et Substances biologiquement actives (LR99ES27) Faculté de Pharmacie de Monastir, Université de Monastir (Tunisia); Kammoun, Dorra [Laboratoire de Biomatériaux et Biotechnologie, Faculté de Médecine Dentaire, Monastir (Tunisia); Hentati, Hajer [Laboratoire de Recherche en Santé Orale et Réhabilitation Bucco-Faciale (LR12ES11), Faculté de Médecine Dentaire de Monastir, Université de Monastir (Tunisia); Janel, Sébastien [BioImaging Center Lille-FR3642, Lille (France); Popoff, Michka [Cellular Microbiology and Physics of Infection-CNRS UMR8204, INSERM U1019, Institut Pasteur de Lille, Lille University (France); Lafont, Frank [BioImaging Center Lille-FR3642, Lille (France); Cellular Microbiology and Physics of Infection-CNRS UMR8204, INSERM U1019, Institut Pasteur de Lille, Lille University (France); Aouni, Mahjoub [Laboratoire des Maladies Transmissibles et Substances biologiquement actives (LR99ES27) Faculté de Pharmacie de Monastir, Université de Monastir (Tunisia); Mastouri, Maha [Laboratoire des Maladies Transmissibles et Substances biologiquement actives (LR99ES27) Faculté de Pharmacie de Monastir, Université de Monastir (Tunisia); Laboratoire de Microbiologie, CHU Fattouma Bourguiba de Monastir (Tunisia)

    2016-08-30

    Highlights: • 4 dental restorative materials were characterized for roughness, angle contact water and surface free energy. • AFM adhesion forces of S. aureus to tested materials were achieved in presence and absence of salivary conditioning film. • S. aureus initial adhesion is dependent on the surface free energy and roughness. - Abstract: In the oral cavity dental restorative biomaterials can act as a reservoir for infection with opportunistic Staphylococcus aureus pathogen, which can lead to the occurrence of secondary caries and treatment failures. Our aim was to evaluate the adhesion forces by S. aureus on four dental restorative biomaterials and to correlate this finding to differences in specific surface characteristics. Additionally, the influence of salivary conditioning films in exerted adhesion forces was investigated. The substrate hydrophobicity was measured by goniometer and the surface free energy was calculated using the equilibrium advancing contact angle values of water, formamide, and diiodomethane on the tested surfaces. The surface roughness was determined using atomic force microscope (AFM). Additionally, cell force spectroscopy was achieved to quantify the forces that drive cell-substrate interactions. S. aureus bacterium exerted a considerable adhesion forces on various dental restorative materials, which decreased in the presence of saliva conditioning film. The influence of the surface roughness and free energy in initial adhesion appears to be more important than the effect of hydrophobicity, either in presence or absence of saliva coating. Hence, control of surface properties of dental restorative biomaterials is of crucial importance in preventing the attachment and subsequent the biofilm formation.

  13. Quantification of Staphylococcus aureus adhesion forces on various dental restorative materials using atomic force microscopy

    International Nuclear Information System (INIS)

    Merghni, Abderrahmen; Kammoun, Dorra; Hentati, Hajer; Janel, Sébastien; Popoff, Michka; Lafont, Frank; Aouni, Mahjoub; Mastouri, Maha

    2016-01-01

    Highlights: • 4 dental restorative materials were characterized for roughness, angle contact water and surface free energy. • AFM adhesion forces of S. aureus to tested materials were achieved in presence and absence of salivary conditioning film. • S. aureus initial adhesion is dependent on the surface free energy and roughness. - Abstract: In the oral cavity dental restorative biomaterials can act as a reservoir for infection with opportunistic Staphylococcus aureus pathogen, which can lead to the occurrence of secondary caries and treatment failures. Our aim was to evaluate the adhesion forces by S. aureus on four dental restorative biomaterials and to correlate this finding to differences in specific surface characteristics. Additionally, the influence of salivary conditioning films in exerted adhesion forces was investigated. The substrate hydrophobicity was measured by goniometer and the surface free energy was calculated using the equilibrium advancing contact angle values of water, formamide, and diiodomethane on the tested surfaces. The surface roughness was determined using atomic force microscope (AFM). Additionally, cell force spectroscopy was achieved to quantify the forces that drive cell-substrate interactions. S. aureus bacterium exerted a considerable adhesion forces on various dental restorative materials, which decreased in the presence of saliva conditioning film. The influence of the surface roughness and free energy in initial adhesion appears to be more important than the effect of hydrophobicity, either in presence or absence of saliva coating. Hence, control of surface properties of dental restorative biomaterials is of crucial importance in preventing the attachment and subsequent the biofilm formation.

  14. Agent-based modeling traction force mediated compaction of cell-populated collagen gels using physically realistic fibril mechanics.

    Science.gov (United States)

    Reinhardt, James W; Gooch, Keith J

    2014-02-01

    Agent-based modeling was used to model collagen fibrils, composed of a string of nodes serially connected by links that act as Hookean springs. Bending mechanics are implemented as torsional springs that act upon each set of three serially connected nodes as a linear function of angular deflection about the central node. These fibrils were evaluated under conditions that simulated axial extension, simple three-point bending and an end-loaded cantilever. The deformation of fibrils under axial loading varied <0.001% from the analytical solution for linearly elastic fibrils. For fibrils between 100 μm and 200 μm in length experiencing small deflections, differences between simulated deflections and their analytical solutions were <1% for fibrils experiencing three-point bending and <7% for fibrils experiencing cantilever bending. When these new rules for fibril mechanics were introduced into a model that allowed for cross-linking of fibrils to form a network and the application of cell traction force, the fibrous network underwent macroscopic compaction and aligned between cells. Further, fibril density increased between cells to a greater extent than that observed macroscopically and appeared similar to matrical tracks that have been observed experimentally in cell-populated collagen gels. This behavior is consistent with observations in previous versions of the model that did not allow for the physically realistic simulation of fibril mechanics. The significance of the torsional spring constant value was then explored to determine its impact on remodeling of the simulated fibrous network. Although a stronger torsional spring constant reduced the degree of quantitative remodeling that occurred, the inclusion of torsional springs in the model was not necessary for the model to reproduce key qualitative aspects of remodeling, indicating that the presence of Hookean springs is essential for this behavior. These results suggest that traction force mediated matrix

  15. The emergence of extracellular matrix mechanics and cell traction forces as important regulators of cellular self-organization.

    Science.gov (United States)

    Checa, Sara; Rausch, Manuel K; Petersen, Ansgar; Kuhl, Ellen; Duda, Georg N

    2015-01-01

    Physical cues play a fundamental role in a wide range of biological processes, such as embryogenesis, wound healing, tumour invasion and connective tissue morphogenesis. Although it is well known that during these processes, cells continuously interact with the local extracellular matrix (ECM) through cell traction forces, the role of these mechanical interactions on large scale cellular and matrix organization remains largely unknown. In this study, we use a simple theoretical model to investigate cellular and matrix organization as a result of mechanical feedback signals between cells and the surrounding ECM. The model includes bi-directional coupling through cellular traction forces to deform the ECM and through matrix deformation to trigger cellular migration. In addition, we incorporate the mechanical contribution of matrix fibres and their reorganization by the cells. We show that a group of contractile cells will self-polarize at a large scale, even in homogeneous environments. In addition, our simulations mimic the experimentally observed alignment of cells in the direction of maximum stiffness and the building up of tension as a consequence of cell and fibre reorganization. Moreover, we demonstrate that cellular organization is tightly linked to the mechanical feedback loop between cells and matrix. Cells with a preference for stiff environments have a tendency to form chains, while cells with a tendency for soft environments tend to form clusters. The model presented here illustrates the potential of simple physical cues and their impact on cellular self-organization. It can be used in applications where cell-matrix interactions play a key role, such as in the design of tissue engineering scaffolds and to gain a basic understanding of pattern formation in organogenesis or tissue regeneration.

  16. The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness

    Directory of Open Access Journals (Sweden)

    Daniel Gandyra

    2015-01-01

    Full Text Available We report a novel, practical technique for the concerted, simultaneous determination of both the adhesion force of a small structure or structural unit (e.g., an individual filament, hair, micromechanical component or microsensor to a liquid and its elastic properties. The method involves the creation and development of a liquid meniscus upon touching a liquid surface with the structure, and the subsequent disruption of this liquid meniscus upon removal. The evaluation of the meniscus shape immediately before snap-off of the meniscus allows the quantitative determination of the liquid adhesion force. Concurrently, by measuring and evaluating the deformation of the structure under investigation, its elastic properties can be determined. The sensitivity of the method is remarkably high, practically limited by the resolution of the camera capturing the process. Adhesion forces down to 10 µN and spring constants up to 2 N/m were measured. Three exemplary applications of this method are demonstrated: (1 determination of the water adhesion force and the elasticity of individual hairs (trichomes of the floating fern Salvinia molesta. (2 The investigation of human head hairs both with and without functional surface coatings (a topic of high relevance in the field of hair cosmetics was performed. The method also resulted in the measurement of an elastic modulus (Young’s modulus for individual hairs of 3.0 × 105 N/cm2, which is within the typical range known for human hair. (3 Finally, the accuracy and validity of the capillary adhesion technique was proven by examining calibrated atomic force microscopy cantilevers, reproducing the spring constants calibrated using other methods.

  17. Effect of capillary condensation on friction force and adhesion.

    Science.gov (United States)

    Feiler, Adam A; Stiernstedt, Johanna; Theander, Katarina; Jenkins, Paul; Rutland, Mark W

    2007-01-16

    Friction force measurements have been conducted with a colloid probe on mica and silica (both hydrophilic and hydrophobized) after long (24 h) exposure to high-humidity air. Adhesion and friction measurements have also been performed on cellulose substrates. The long exposure to high humidity led to a large hysteresis between loading and unloading in the friction measurements with separation occurring at large negative applied loads. The large hysteresis in the friction-load relationship is attributed to a contact area hysteresis of the capillary condensate which built up during loading and did not evaporate during the unloading regime. The magnitude of the friction force varied dramatically between substrates and was lowest on the mica substrate and highest on the hydrophilic silica substrate, with the hydrophobized silica and cellulose being intermediate. The adhesion due to capillary forces on cellulose was small compared to that on the other substrates, due to the greater roughness of these surfaces.

  18. Traction Stresses Exerted by Adherent Cells: From Angiogenesis to Metastasis

    Science.gov (United States)

    Reinhart-King, Cynthia

    2010-03-01

    Cells exert traction stresses against their substrate that mediate their ability to sense the mechanical properties of their microenvironment. These same forces mediate cell adhesion, migration and the formation of stable cell-cell contacts during tissue formation. In this talk, I will present our data on the traction stresses generated by endothelial cells and metastatic breast cancer cells focused on understanding the processes of angiogenesis and metastasis, respectively. In the context of capillary formation, our data indicate that the mechanics of the substrate play a critical role in establishing endothelial cell-cell contacts. On more compliant substrates, endothelial cell shape and traction stresses polarize and promote the formation of stable cell-cell contacts. On stiffer substrates, traction stresses are less polarized and cell connectivity is disrupted. These data indicate that the mechanical properties of the microenvironment may drive cell connectivity and the formation of stable cell-cell contacts through the reorientation of traction stresses. In our studies of metastatic cell migration, we have found that traction stresses increase with increasing metastatic potential. We investigated three lines of varying metastatic potential (MCF10A, MCF7 and MDAMB231). MDAMB231, which are the most invasive, exert the most significant forces as measured by Traction Force Microscopy. These data present the possibility that cellular traction stress generation aids in the ability of metastatic cells to migrate through the matrix-dense tumor microenvironment. Such measurements are integral to link the mechanical and chemical microenvironment with the resulting response of the cell in health and disease.

  19. Adhesive force of a single gecko foot-hair

    Science.gov (United States)

    Autumn, Kellar; Liang, Yiching A.; Hsieh, S. Tonia; Zesch, Wolfgang; Chan, Wai Pang; Kenny, Thomas W.; Fearing, Ronald; Full, Robert J.

    2000-06-01

    Geckos are exceptional in their ability to climb rapidly up smooth vertical surfaces. Microscopy has shown that a gecko's foot has nearly five hundred thousand keratinous hairs or setae. Each 30-130µm long seta is only one-tenth the diameter of a human hair and contains hundreds of projections terminating in 0.2-0.5µm spatula-shaped structures. After nearly a century of anatomical description, here we report the first direct measurements of single setal force by using a two-dimensional micro-electro-mechanical systems force sensor and a wire as a force gauge. Measurements revealed that a seta is ten times more effective at adhesion than predicted from maximal estimates on whole animals. Adhesive force values support the hypothesis that individual seta operate by van der Waals forces. The gecko's peculiar behaviour of toe uncurling and peeling led us to discover two aspects of setal function which increase their effectiveness. A unique macroscopic orientation and preloading of the seta increased attachment force 600-fold above that of frictional measurements of the material. Suitably orientated setae reduced the forces necessary to peel the toe by simply detaching above a critical angle with the substratum.

  20. Cell origami: self-folding of three-dimensional cell-laden microstructures driven by cell traction force.

    Directory of Open Access Journals (Sweden)

    Kaori Kuribayashi-Shigetomi

    Full Text Available This paper describes a method of generating three-dimensional (3D cell-laden microstructures by applying the principle of origami folding technique and cell traction force (CTF. We harness the CTF as a biological driving force to fold the microstructures. Cells stretch and adhere across multiple microplates. Upon detaching the microplates from a substrate, CTF causes the plates to lift and fold according to a prescribed pattern. This self-folding technique using cells is highly biocompatible and does not involve special material requirements for the microplates and hinges to induce folding. We successfully produced various 3D cell-laden microstructures by just changing the geometry of the patterned 2D plates. We also achieved mass-production of the 3D cell-laden microstructures without causing damage to the cells. We believe that our methods will be useful for biotechnology applications that require analysis of cells in 3D configurations and for self-assembly of cell-based micro-medical devices.

  1. Cell origami: self-folding of three-dimensional cell-laden microstructures driven by cell traction force.

    Science.gov (United States)

    Kuribayashi-Shigetomi, Kaori; Onoe, Hiroaki; Takeuchi, Shoji

    2012-01-01

    This paper describes a method of generating three-dimensional (3D) cell-laden microstructures by applying the principle of origami folding technique and cell traction force (CTF). We harness the CTF as a biological driving force to fold the microstructures. Cells stretch and adhere across multiple microplates. Upon detaching the microplates from a substrate, CTF causes the plates to lift and fold according to a prescribed pattern. This self-folding technique using cells is highly biocompatible and does not involve special material requirements for the microplates and hinges to induce folding. We successfully produced various 3D cell-laden microstructures by just changing the geometry of the patterned 2D plates. We also achieved mass-production of the 3D cell-laden microstructures without causing damage to the cells. We believe that our methods will be useful for biotechnology applications that require analysis of cells in 3D configurations and for self-assembly of cell-based micro-medical devices.

  2. Theoretical study of the effect of probe shape on adhesion force between probe and substrate in atomic force microscope experiment

    OpenAIRE

    Yang, Li; Hu, Junhui; Kong, Lingjiang

    2017-01-01

    The quantitative description of adhesion force dependence on the probe shapes are of importance in many scientific and industrial fields. In order to elucidate how the adhesion force varied with the probe shape in atomic force microscope manipulation experiment, we performed a theoretical study of the influences of the probe shape (the sphere and parabolic probe) on the adhesion force at different humidity. We found that the combined action of the triple point and the Kelvin radius guiding th...

  3. Surface adhesion properties of graphene and graphene oxide studied by colloid-probe atomic force microscopy

    International Nuclear Information System (INIS)

    Ding Yanhuai; Zhang Ping; Ren Huming; Zhuo Qin; Yang Zhongmei; Jiang Xu; Jiang Yong

    2011-01-01

    Surface adhesion properties are important to various applications of graphene-based materials. Atomic force microscopy is powerful to study the adhesion properties of samples by measuring the forces on the colloidal sphere tip as it approaches and retracts from the surface. In this paper we have measured the adhesion force between the colloid probe and the surface of graphene (graphene oxide) nanosheet. The results revealed that the adhesion force on graphene and graphene oxide surface were 66.3 and 170.6 nN, respectively. It was found the adhesion force was mainly determined by the water meniscus, which was related to the surface contact angle of samples.

  4. Quantitative measurement of changes in adhesion force involving focal adhesion kinase during cell attachment, spread, and migration

    International Nuclear Information System (INIS)

    Wu, C.-C.; Su, H.-W.; Lee, C.-C.; Tang, M.-J.; Su, F.-C.

    2005-01-01

    Focal adhesion kinase (FAK) is a critical protein for the regulation of integrin-mediated cellular functions and it can enhance cell motility in Madin-Darby canine kidney (MDCK) cells by hepatocyte growth factor (HGF) induction. We utilized optical trapping and cytodetachment techniques to measure the adhesion force between pico-Newton and nano-Newton (nN) for quantitatively investigating the effects of FAK on adhesion force during initial binding (5 s), beginning of spreading (30 min), spreadout (12 h), and migration (induced by HGF) in MDCK cells with overexpressed FAK (FAK-WT), FAK-related non-kinase (FRNK), as well as normal control cells. Optical tweezers was used to measure the initial binding force between a trapped cell and glass coverslide or between a trapped bead and a seeded cell. In cytodetachment, the commercial atomic force microscope probe with an appropriate spring constant was used as a cyto-detacher to evaluate the change of adhesion force between different FAK expression levels of cells in spreading, spreadout, and migrating status. The results demonstrated that FAK-WT significantly increased the adhesion forces as compared to FRNK cells throughout all the different stages of cell adhesion. For cells in HGF-induced migration, the adhesion force decreased to almost the same level (∼600 nN) regardless of FAK levels indicating that FAK facilitates cells to undergo migration by reducing the adhesion force. Our results suggest FAK plays a role of enhancing cell adhesive ability in the binding and spreading, but an appropriate level of adhesion force is required for HGF-induced cell migration

  5. The influence of aerodynamic forces on the vehicle bodywork of railway traction

    Directory of Open Access Journals (Sweden)

    Sorin ARSENE

    2016-03-01

    Full Text Available The increase of the driving speed in railway system requires a comprehensive analysis on the vehicle aerodynamics, on the manner in which the performance is affected or related to the additional loads on various components. The aerodynamic forces have a greater impact in the case of medium and high values of the relative velocity of the air flow near the vehicle. This paper aims to analyze the loads caused by the aerodynamic forces on the bodywork of the electric locomotive, of 5100 kW LE 060 EA type. In this respect, the bodywork and the chassis of locomotive were modelled in a 3D format; then a series of air flow simulations were performed for different values of the vehicle velocity ranging between 0 km/h and 200 km/h.

  6. Investigating single molecule adhesion by atomic force spectroscopy.

    Science.gov (United States)

    Stetter, Frank W S; Kienle, Sandra; Krysiak, Stefanie; Hugel, Thorsten

    2015-02-27

    Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. At the same time the AFM tip is passivated to prevent unspecific interactions between the tip and the substrate, which is a prerequisite to study single molecules attached to the AFM tip. Analyses to determine the adhesion force, the adhesion length, and the free energy of these molecules on solid surfaces and bio-interfaces are shortly presented and external references for further reading are provided. Example molecules are the poly(amino acid) polytyrosine, the graft polymer PI-g-PS and the phospholipid POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine). These molecules are desorbed from different surfaces like CH3-SAMs, hydrogen terminated diamond and supported lipid bilayers under various solvent conditions. Finally, the advantages of force spectroscopic single molecule experiments are discussed including means to decide if truly a single molecule has been studied in the experiment.

  7. The adhesion force of Notch with Delta and the rate of Notch signaling

    OpenAIRE

    Ahimou, Francois; Mok, Lee-Peng; Bardot, Boris; Wesley, Cedric

    2004-01-01

    Notch signaling is repeatedly used during animal development to specify cell fates. Using atomic force microscopy on live cells, chemical inhibitors, and conventional analyses, we show that the rate of Notch signaling is linked to the adhesion force between cells expressing Notch receptors and Delta ligand. Both the Notch extracellular and intracellular domains are required for the high adhesion force with Delta. This high adhesion force is lost within minutes, primarily due to the action of ...

  8. Studying the Adhesion Force and Glass Transition of Thin Polystyrene Films by Atomic Force Microscopy

    DEFF Research Database (Denmark)

    Kang, Hua; Qian, Xiaoqin; Guan, Li

    2018-01-01

    microscopy (AFM)-based forcedistance curve to study the relaxation dynamics and the film thickness dependence of glass transition temperature (T-g) for normal thin polystyrene (PS) films supported on silicon substrate. The adhesion force (F-ad) between AFM tip and normal thin PS film surfaces...

  9. AFM measurements of adhesive forces between carbonaceous particles and the substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tianqi [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Peng, Wei, E-mail: pengwei@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Shen, Ke [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Yu, Suyuan, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Educations, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

    2015-11-15

    Highlights: • Adhesive force of spherical carbonaceous particle MCMBs and HTR-10 graphite matrix debris were measured for the first time. • The measured equivalent works of adhesion were much smaller than the ideal values. • The shape factor and the particle morphology reduce the adhesive force. • The adhesion effect does not change directly with the asperity size. - Abstract: Graphite dust is carbonaceous particles generated during operation of High Temperature Gas-Cooled Reactors (HTR). Graphite dust resuspension is the key behavior associated with HTR source term analyses and environmental safety assessment. The adhesive force is the key factor that determines the resuspension rate. The present study used an atomic force microscope (AFM) to measure the adhesive force between a single carbonaceous particle and the substrate. The measurements were performed on mica, graphite IG110 and Inconel 800H. The prepared “probe cantilevers” were mesocarbon microbeads (MCMB), fuel element debris from HTR-10 and graphite NBG18. The equivalent work of adhesion was derived from the measured adhesive force and calculated based on substrate profile approximation and the JKR theoretical model. The measured work was smaller than the ideal work of adhesion, most likely due to the rough particle morphology and the rough substrate surface. Additionally, a shape factor imposes a constraint on the lateral deformation of the particles. Furthermore, surface roughness could reduce the adhesive force some depending on the particle size. Once the particle was too small to be trapped into a trough, the adhesive force would not be further reduced.

  10. AFM measurements of adhesive forces between carbonaceous particles and the substrates

    International Nuclear Information System (INIS)

    Zhang, Tianqi; Peng, Wei; Shen, Ke; Yu, Suyuan

    2015-01-01

    Highlights: • Adhesive force of spherical carbonaceous particle MCMBs and HTR-10 graphite matrix debris were measured for the first time. • The measured equivalent works of adhesion were much smaller than the ideal values. • The shape factor and the particle morphology reduce the adhesive force. • The adhesion effect does not change directly with the asperity size. - Abstract: Graphite dust is carbonaceous particles generated during operation of High Temperature Gas-Cooled Reactors (HTR). Graphite dust resuspension is the key behavior associated with HTR source term analyses and environmental safety assessment. The adhesive force is the key factor that determines the resuspension rate. The present study used an atomic force microscope (AFM) to measure the adhesive force between a single carbonaceous particle and the substrate. The measurements were performed on mica, graphite IG110 and Inconel 800H. The prepared “probe cantilevers” were mesocarbon microbeads (MCMB), fuel element debris from HTR-10 and graphite NBG18. The equivalent work of adhesion was derived from the measured adhesive force and calculated based on substrate profile approximation and the JKR theoretical model. The measured work was smaller than the ideal work of adhesion, most likely due to the rough particle morphology and the rough substrate surface. Additionally, a shape factor imposes a constraint on the lateral deformation of the particles. Furthermore, surface roughness could reduce the adhesive force some depending on the particle size. Once the particle was too small to be trapped into a trough, the adhesive force would not be further reduced.

  11. The adhesion force of Notch with Delta and the rate of Notch signaling.

    Science.gov (United States)

    Ahimou, Francois; Mok, Lee-Peng; Bardot, Boris; Wesley, Cedric

    2004-12-20

    Notch signaling is repeatedly used during animal development to specify cell fates. Using atomic force microscopy on live cells, chemical inhibitors, and conventional analyses, we show that the rate of Notch signaling is linked to the adhesion force between cells expressing Notch receptors and Delta ligand. Both the Notch extracellular and intracellular domains are required for the high adhesion force with Delta. This high adhesion force is lost within minutes, primarily due to the action of Presenilin on Notch. Reduced turnover or Delta pulling accelerate this loss. These data suggest that strong adhesion between Notch and Delta might serve as a booster for initiating Notch signaling at a high rate.

  12. Behavior of adhesion forces of silicone adhesive sealants and mastic butyl under the influence of ionizing radiation

    International Nuclear Information System (INIS)

    Costa, Wanderley da

    2012-01-01

    Adhesives are products that can keep materials together by bonds between the surfaces. Sealants are products that can keep filled a space between two surfaces, through a barrier that is configured as a 'bridge' between the two surfaces. The mastic is a product made of a mixture of substances with the primary butyl polymer, with the consistency of a mass not dried that can be used as a sealant. The polysiloxane, also known as silicone are the most important synthetic polymers with inorganic structure, and are matrices of silicone adhesive sealants. To demonstrate the behavior of the adhesive forces of these products under different conditions, we used five different techniques. These products were subjected to two different conditions to verify the behavior of adhesion, one at the environmental condition and another under the ionizing radiation. The results showed not only differences between products (silicone and mastic), but also that the adhesive forces have different behaviors under the conditions which the samples were subjected. With this was reached the goal of this study that aspired show the differences between the mastic and silicone, this last one is often considered - erroneously - the same as mastic. Thus it was proven that: 1. silicone can be regarded as an adhesive and a sealant at ambient conditions, 2. mastic improves substantially adhesion in an environment of ionizing radiation and this property can be an excellent alternative to the adhesive market. (author)

  13. Open coil traction system.

    Science.gov (United States)

    Vibhute, Pavankumar Janardan

    2012-01-01

    Sliding mechanics have become a popular method for space closure, with the development of preadjusted edgewise appliances. Furthermore, various space closing auxiliaries have been developed and extensively evaluated for their clinical efficiency. Their effectiveness is enhanced with optimum force magnitude and low load deflection rate/force decay. With the advent of nickel-titanium (Ni-Ti) springs in orthodontics, load deflection rates have been markedly reduced. To use Ni-Ti springs, clinicians have to depend upon prefabricated closed coil springs. The open coil traction system, or open coil retraction spring, is developed utilizing Ni-Ti open coil springs for orthodontic space closure. This article describes the fabrication and clinical application of the open coil traction system, which has a number of advantages. It sustains a low load deflection rate with optimum force magnitude, and its design is adjustable for a desired length and force level. It is fail-safe for both activation and deactivation (ie, it cannot be overactivated, and the decompression limit of the open coil is controlled by the operator). The open coil traction system can be offset from the mucosa to help reduce soft tissue impingement.

  14. Bacterial Adhesion Forces to Ag-Impregnated Contact Lens Cases and Transmission to Contact Lenses

    NARCIS (Netherlands)

    Qu, Wenwen; Busscher, Henk J.; van der Mei, Henny C.; Hooymans, Johanna M. M.

    Purpose: To measure adhesion forces of Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens to a rigid contact lens (CL), standard polypropylene, and Ag-impregnated lens cases using atomic force microscopy and determine bacterial transmission from lens case to CL. Methods: Adhesion

  15. Bond-Strengthening in Staphylococcal Adhesion to Hydrophilic and Hydrophobic Surfaces Using Atomic Force Microscopy

    NARCIS (Netherlands)

    Boks, N.P.; Busscher, H.J.; Mei, van der H.C.; Norde, W.

    2008-01-01

    Time-dependent bacterial adhesion forces of four strains of Staphylococcus epidermidis to hydrophobic and hydrophilic surfaces were investigated. Initial adhesion forces differed significantly between the two surfaces and hovered around -0.4 nN. No unambiguous effect of substratum surface

  16. Probing living bacterial adhesion by single cell force spectroscopy using atomic force microscopy

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Ogaki, Ryosuke; Regina, Viduthalai R.

    be considered. We have therefore developed a simple and versatile method to make single-cell bacterial probes for measuring single cell adhesion with atomic force microscopy (AFM).[1] A single-cell probe was readily made by picking up a bacterial cell from a glass surface using a tipless AFM cantilever coated...... random immobilization is obtained by submerging the cantilever in a bacterial suspension. The reported method provides a general platform for investigating single cell interactions of bacteria with different surfaces and other cells by AFM force spectroscopy, thus improving our understanding....... The strain-dependent susceptibility to bacterial colonization on conventional PLL-g-PEG illustrates how bacterial diversity challenges development of “universal” antifouling coatings, and AFM single-cell force spectroscopy was proven to be a powerful tool to provide insights into the molecular mechanisms...

  17. Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces.

    Science.gov (United States)

    Oras, Sven; Vlassov, Sergei; Berholts, Marta; Lõhmus, Rünno; Mougin, Karine

    2018-01-01

    Adhesion forces between functionalized gold colloidal nanoparticles (Au NPs) and scanning probe microscope silicon tips were experimentally investigated by atomic force microscopy (AFM) equipped with PeakForce QNM (Quantitative Nanoscale Mechanics) module. Au NPs were synthesized by a seed-mediated process and then functionalized with thiols containing different functional groups: amino, hydroxy, methoxy, carboxy, methyl, and thiol. Adhesion measurements showed strong differences between NPs and silicon tip depending on the nature of the tail functional group. The dependence of the adhesion on ligand density for different thiols with identical functional tail-group was also demonstrated. The calculated contribution of the van der Waals (vdW) forces between particles was in good agreement with experimentally measured adhesive values. In addition, the adhesion forces were evaluated between flat Au films functionalized with the same molecular components and silicon tips to exclude the effect of particle shape on the adhesion values. Although adhesion values on flat substrates were higher than on their nanoparticle counterparts, the dependance on functional groups remained the same.

  18. Force-Induced Calpain Cleavage of Talin Is Critical for Growth, Adhesion Development, and Rigidity Sensing.

    Science.gov (United States)

    Saxena, Mayur; Changede, Rishita; Hone, James; Wolfenson, Haguy; Sheetz, Michael P

    2017-12-13

    Cell growth depends upon formation of cell-matrix adhesions, but mechanisms detailing the transmission of signals from adhesions to control proliferation are still lacking. Here, we find that the scaffold protein talin undergoes force-induced cleavage in early adhesions to produce the talin rod fragment that is needed for cell cycle progression. Expression of noncleavable talin blocks cell growth, adhesion maturation, proper mechanosensing, and the related property of EGF activation of motility. Further, the expression of talin rod in the presence of noncleavable full-length talin rescues cell growth and other functions. The cleavage of talin is found in early adhesions where there is also rapid turnover of talin that depends upon calpain and TRPM4 activity as well as the generation of force on talin. Thus, we suggest that an important function of talin is its control over cell cycle progression through its cleavage in early adhesions.

  19. Osteopontin adsorption to Gram-positive cells reduces adhesion forces and attachment to surfaces under flow

    DEFF Research Database (Denmark)

    Kristensen, M F; Zeng, G; Neu, T R

    2017-01-01

    caries or medical device-related infections. It further investigated if OPN's effect on adhesion is caused by blocking the accessibility of glycoconjugates on bacterial surfaces. Bacterial adhesion was determined in a shear-controlled flow cell system in the presence of different concentrations of OPN......The bovine milk protein osteopontin (OPN) may be an efficient means to prevent bacterial adhesion to dental tissues and control biofilm formation. This study sought to determine to what extent OPN impacts adhesion forces and surface attachment of different bacterial strains involved in dental......, and interaction forces of single bacteria were quantified using single-cell force spectroscopy before and after OPN exposure. Moreover, the study investigated OPN's effect on the accessibility of cell surface glycoconjugates through fluorescence lectin-binding analysis. OPN strongly affected bacterial adhesion...

  20. Wall Climbing Robot Using Electrostatic Adhesion Force Generated by Flexible Interdigital Electrodes

    Directory of Open Access Journals (Sweden)

    Rong Liu

    2013-01-01

    Full Text Available Electrostatic adhesion technology has broad application prospects on wall climbing robots because of its unique characteristics compared with other types of adhesion technologies. A double tracked wall climbing robot based on electrostatic adhesion technology is presented including electrode panel design, mechanical structure design, power supply system design and control system design. A theoretical adhesion model was established and the electrostatic potential and field were expressed by series expansions in terms of solutions of the Laplace function. Based on this model, the electrostatic adhesion force was calculated using the Maxwell stress tensor formulation. Several important factors which may influence the electrostatic adhesion force were analysed and discussed by both FEM simulation and theoretical calculation. In addition, experiments on the adhesion performance of the electrode panel and the climbing performance of the robot on various wall materials were carried out. Both the simulation and experiment results verify the feasibility of electrostatic adhesion technology being applied on wall climbing robots. The theoretical model and calculation method for the electrostatic adhesion force proposed in this paper are also justified.

  1. Influence of surface roughness on streptococcal adhesion forces to composite resins

    NARCIS (Netherlands)

    Mei, Li; Busscher, Henk J; van der Mei, Henny C; Ren, Yijin

    OBJECTIVE: To determine streptococcal adhesion forces with composite resins with different surface roughness. METHODS: Polishing and grinding were applied to obtain smooth (roughness 20 nm), moderately rough (150 nm) and rough (350 nm) surfaces of two orthodontic, light-cured composites. Adhesion

  2. Adhesion Forces and Coaggregation between Vaginal Staphylococci and Lactobacilli

    NARCIS (Netherlands)

    Younes, Jessica A.; van der Mei, Henny C.; van den Heuvel, Edwin; Busscher, Henk J.; Reid, Gregor

    2012-01-01

    Urogenital infections are the most common ailments afflicting women. They are treated with dated antimicrobials whose efficacy is diminishing. The process of infection involves pathogen adhesion and displacement of indigenous Lactobacillus crispatus and Lactobacillus jensenii. An alternative

  3. Superhydrophobic gecko feet with high adhesive forces towards water and their bio-inspired materials

    Science.gov (United States)

    Liu, Kesong; Du, Jiexing; Wu, Juntao; Jiang, Lei

    2012-01-01

    Functional integration is an inherent characteristic for multiscale structures of biological materials. In this contribution, we first investigate the liquid-solid adhesive forces between water droplets and superhydrophobic gecko feet using a high-sensitivity micro-electromechanical balance system. It was found, in addition to the well-known solid-solid adhesion, the gecko foot, with a multiscale structure, possesses both superhydrophobic functionality and a high adhesive force towards water. The origin of the high adhesive forces of gecko feet to water could be attributed to the high density nanopillars that contact the water. Inspired by this, polyimide films with gecko-like multiscale structures were constructed by using anodic aluminum oxide templates, exhibiting superhydrophobicity and a strong adhesive force towards water. The static water contact angle is larger than 150° and the adhesive force to water is about 66 μN. The resultant gecko-inspired polyimide film can be used as a ``mechanical hand'' to snatch micro-liter liquids. We expect this work will provide the inspiration to reveal the mechanism of the high-adhesive superhydrophobic of geckos and extend the practical applications of polyimide materials.

  4. Influence of removal time and particle size on the particle substrate adhesion force

    Directory of Open Access Journals (Sweden)

    M. A. Felicetti

    2008-03-01

    Full Text Available An investigation was conducted on influence of removal time on the particle substrate adhesive force. The centrifuge technique was used to determine the adhesion force at different compression and removal rates. A microcentrifuge with a maximum rotation of 14000 rpm was used to both compress upon particles and remove them from the surface of the substrate. An image analysis program (Image-Pro Plus 4.5 was employed to monitor the number of particles adhering to and removed from the surface of the substrate after each increase in angular speed. The influence of removal time on the adhesion force was investigated, using removal times of 1, 3 and 5 minutes, which indicated that removal time does not interfere with the adhesion force within the diameter range analyzed here.

  5. Rapid and serial quantification of adhesion forces of yeast and Mammalian cells.

    Directory of Open Access Journals (Sweden)

    Eva Potthoff

    Full Text Available Cell adhesion to surfaces represents the basis for niche colonization and survival. Here we establish serial quantification of adhesion forces of different cell types using a single probe. The pace of single-cell force-spectroscopy was accelerated to up to 200 yeast and 20 mammalian cells per probe when replacing the conventional cell trapping cantilever chemistry of atomic force microscopy by underpressure immobilization with fluidic force microscopy (FluidFM. In consequence, statistically relevant data could be recorded in a rapid manner, the spectrum of examinable cells was enlarged, and the cell physiology preserved until approached for force spectroscopy. Adhesion forces of Candida albicans increased from below 4 up to 16 nN at 37°C on hydrophobic surfaces, whereas a Δhgc1-mutant showed forces consistently below 4 nN. Monitoring adhesion of mammalian cells revealed mean adhesion forces of 600 nN of HeLa cells on fibronectin and were one order of magnitude higher than those observed for HEK cells.

  6. Potential dependent adhesion forces on bare and underpotential deposition modified electrode surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Serafin, J.M.; Hsieh, S.J.; Monahan, J.; Gewirth, A.A. [Univ. of Illinois, Urbana, IL (United States)

    1998-12-03

    Adhesion force measurements are used to determine the potential dependence of the force of adhesion between a Si{sub 3}N{sub 4} cantilever and a Au(111) surface modified by the underpotential deposition (upd) of Bi or Cu in acid solution or by oxide formation. The measured work of adhesion is near zero for most of the potential region examined in Bi upd but rises after the formation of a full Bi monolayer. The work of adhesion is high at positive potentials for Cu upd but then decreases as the Cu partial and full monolayers are formed. The work of adhesion is low in the oxide region on Au(111) but rises following the sulfate disordering transition at 1.1 V vs NHE. These results are interpreted in terms of the degree of solvent order on the electrode surface.

  7. Superhydrophobic Zr-based metallic glass surface with high adhesive force

    Science.gov (United States)

    Li, Ning; Xia, Ting; Heng, Liping; Liu, Lin

    2013-06-01

    Micro/nano hierarchical structures were constructed on Zr35Ti30Be26.75Cu8.25 metallic glass surface by silicon moulding and subsequently chemical etching. The as-formed surface exhibited both superhydrophobicity and high adhesive force towards water. The superhydrophobicity is rationalized based on the modified Cassie-Baxter model [A. B. D. Cassie and S. Baxter, Trans. Faraday Soc. 40, 546 (1944)]. The origin of the robust adhesion is described in terms of intermolecular capillary forces. The present results not only provide a method to fabricate superhydrophobic metallic glasses surface but also explore an important industrial application as dry adhesives and transport of liquid microdroplets.

  8. Study of adhesion of vertically aligned carbon nanotubes to a substrate by atomic-force microscopy

    Science.gov (United States)

    Ageev, O. A.; Blinov, Yu. F.; Il'ina, M. V.; Il'in, O. I.; Smirnov, V. A.; Tsukanova, O. G.

    2016-02-01

    The adhesion to a substrate of vertically aligned carbon nanotubes (VA CNT) produced by plasmaenhanced chemical vapor deposition has been experimentally studied by atomic-force microscopy in the current spectroscopy mode. The longitudinal deformation of VA CNT by applying an external electric field has been simulated. Based on the results, a technique of determining VA CNT adhesion to a substrate has been developed that is used to measure the adhesion strength of connecting VA CNT to a substrate. The adhesion to a substrate of VA CNT 70-120 nm in diameter varies from 0.55 to 1.19 mJ/m2, and the adhesion force from 92.5 to 226.1 nN. When applying a mechanical load, the adhesion strength of the connecting VA CNT to a substrate is 714.1 ± 138.4 MPa, and the corresponding detachment force increases from 1.93 to 10.33 μN with an increase in the VA CNT diameter. As an external electric field is applied, the adhesion strength is almost doubled and is 1.43 ± 0.29 GPa, and the corresponding detachment force is changed from 3.83 to 20.02 μN. The results can be used in the design of technological processes of formation of emission structures, VA CNT-based elements for vacuum microelectronics and micro- and nanosystem engineering, and also the methods of probe nanodiagnostics of VA CNT.

  9. Single molecule force measurements delineate salt, pH and surface effects on biopolymer adhesion

    International Nuclear Information System (INIS)

    Pirzer, T; Geisler, M; Hugel, T; Scheibel, T

    2009-01-01

    In this paper we probe the influence of surface properties, pH and salt on the adhesion of recombinant spider silk proteins onto solid substrates with single molecule force spectroscopy. A single engineered spider silk protein (monomeric C 16 or dimeric (QAQ) 8 NR3) is covalently bound with one end to an AFM tip, which assures long-time measurements for hours with one and the same protein. The tip with the protein is brought into contact with various substrates at various buffer conditions and then retracted to desorb the protein. We observe a linear dependence of the adhesion force on the concentration of three selected salts (NaCl, NaH 2 PO 4 and NaI) and a Hofmeister series both for anions and cations. As expected, the more hydrophobic C 16 shows a higher adhesion force than (QAQ) 8 NR3, and the adhesion force rises with the hydrophobicity of the substrate. Unexpected is the magnitude of the dependences—we never observe a change of more than 30%, suggesting a surprisingly well-regulated balance between dispersive forces, water-structure-induced forces as well as co-solute-induced forces in biopolymer adhesion

  10. Single molecule force measurements delineate salt, pH and surface effects on biopolymer adhesion

    Science.gov (United States)

    Pirzer, T.; Geisler, M.; Scheibel, T.; Hugel, T.

    2009-06-01

    In this paper we probe the influence of surface properties, pH and salt on the adhesion of recombinant spider silk proteins onto solid substrates with single molecule force spectroscopy. A single engineered spider silk protein (monomeric C16 or dimeric (QAQ)8NR3) is covalently bound with one end to an AFM tip, which assures long-time measurements for hours with one and the same protein. The tip with the protein is brought into contact with various substrates at various buffer conditions and then retracted to desorb the protein. We observe a linear dependence of the adhesion force on the concentration of three selected salts (NaCl, NaH2PO4 and NaI) and a Hofmeister series both for anions and cations. As expected, the more hydrophobic C16 shows a higher adhesion force than (QAQ)8NR3, and the adhesion force rises with the hydrophobicity of the substrate. Unexpected is the magnitude of the dependences—we never observe a change of more than 30%, suggesting a surprisingly well-regulated balance between dispersive forces, water-structure-induced forces as well as co-solute-induced forces in biopolymer adhesion.

  11. The effect of adhesion on the contact radius in atomic force microscopy indentation

    International Nuclear Information System (INIS)

    Sirghi, L; Rossi, F

    2009-01-01

    The effect of adhesion on nanoscale indentation experiments makes the interpretation of force-displacement curves acquired in these experiments very difficult. The indentation force results from the addition of adhesive and elastic forces at the indenter-sample contact. The evolution of the two forces during the indentation is determined by the variation of the indenter-sample contact radius. In the present work the variation of contact radius during atomic force microscopy (AFM) indentation of elastic and adhesive samples with conical indenters (AFM tips) is indirectly determined by measurements of the contact dynamic stiffness. For weak sample deformations, the contact radius is determined mainly by the adhesion force and indenter apex radius. For strong sample deformations, the contact radius increases linearly with the increase of the indenter displacement, the slope of this linear dependence being in agreement with Sneddon's theory of indentation (Sneddon 1965 Int. J. Eng. Sci. 3 47). Based on these results, a theoretical expression of indentation force dependence on displacement is found. This expression allows for determination of the thermodynamic work of adhesion at the indenter-sample interface and the sample elasticity modulus.

  12. Evaluation of adhesion forces of Staphylococcus aureus along the length of Candida albicans hyphae.

    Science.gov (United States)

    Ovchinnikova, Ekaterina S; Krom, Bastiaan P; Busscher, Henk J; van der Mei, Henny C

    2012-11-27

    Candida albicans is a human fungal pathogen, able to cause both superficial and serious, systemic diseases and is able to switch from yeast cells to long, tube-like hyphae, depending on the prevailing environmental conditions. Both morphological forms of C. albicans are found in infected tissue, often in combination with Staphylococcus aureus. Although bacterial adhesion to the different morphologies of C. albicans has been amply studied, possible differences in staphylococcal adhesion forces along the length of C. albicans hyphae have never been determined. In this study, we aim to verify the hypothesis that the forces mediating S. aureus NCTC8325-4GFP adhesion to hyphae vary along the length of C. albicans SC5314 and MB1 hyphae, as compared with adhesion to yeast cells. C. albicans hyphae were virtually divided into a "tip" (the growing and therefore youngest part of the hyphae), a "middle" and a so-called "head" region (the yeast cell from which germination started). Adhesion forces between S. aureus NCTC8325-4GFP and the different regions of C. albicans SC5314 hyphae were measured using atomic force microscopy. Strong adhesion forces were found at the tip and middle regions of C. albicans hyphae (-4.1 nN and -4.0 nN, respectively), while much smaller adhesion forces were measured at the head region (-0.3 nN). Adhesion forces exerted by the head region were comparable with the forces arising from budding yeast cells (-0.5 nN). A similar regional dependence of the staphylococcal adhesion forces was found for the clinical isolate involved in this study, C. albicans MB1. This is the first time that differences in adhesion forces between S. aureus and different regions of C. albicans hyphae have been demonstrated on a quantitative basis, supporting the view that the head region is different from the remainder of the hyphae. Notably it can be concluded that the properties of the hyphal head region are similar to those of budding yeast cells. These novel findings

  13. Adhesion

    Science.gov (United States)

    ... Supplements Videos & Tools Español You Are Here: Home → Medical Encyclopedia → Adhesion URL of this page: //medlineplus.gov/ency/article/001493.htm Adhesion To use the sharing features on this page, please enable JavaScript. Adhesions are bands of scar-like tissue that form between two ...

  14. Single Cell Force Spectroscopy for Quantification of Cellular Adhesion on Surfaces

    Science.gov (United States)

    Christenson, Wayne B.

    Cell adhesion is an important aspect of many biological processes. The atomic force microscope (AFM) has made it possible to quantify the forces involved in cellular adhesion using a technique called single cell force spectroscopy (SCFS). AFM based SCFS offers versatile control over experimental conditions for probing directly the interaction between specific cell types and specific proteins, surfaces, or other cells. Transmembrane integrins are the primary proteins involved in cellular adhesion to the extra cellular matix (ECM). One of the chief integrins involved in the adhesion of leukocyte cells is alpha Mbeta2 (Mac-1). The experiments in this dissertation quantify the adhesion of Mac-1 expressing human embryonic kidney (HEK Mac-1), platelets, and neutrophils cells on substrates with different concentrations of fibrinogen and on fibrin gels and multi-layered fibrinogen coated fibrin gels. It was shown that multi-layered fibrinogen reduces the adhesion force of these cells considerably. A novel method was developed as part of this research combining total internal reflection microscopy (TIRFM) with SCFS allowing for optical microscopy of HEK Mac-1 cells interacting with bovine serum albumin (BSA) coated glass after interacting with multi-layered fibrinogen. HEK Mac-1 cells are able to remove fibrinogen molecules from the multi-layered fibrinogen matrix. An analysis methodology for quantifying the kinetic parameters of integrin-ligand interactions from SCFS experiments is proposed, and the kinetic parameters of the Mac-1 fibrinogen bond are quantified. Additional SCFS experiments quantify the adhesion of macrophages and HEK Mac-1 cells on functionalized glass surfaces and normal glass surfaces. Both cell types show highest adhesion on a novel functionalized glass surface that was prepared to induce macrophage fusion. These experiments demonstrate the versatility of AFM based SCFS, and how it can be applied to address many questions in cellular biology offering

  15. Measurement of cell adhesion force by vertical forcible detachment using an arrowhead nanoneedle and atomic force microscopy

    International Nuclear Information System (INIS)

    Ryu, Seunghwan; Hashizume, Yui; Mishima, Mari; Kawamura, Ryuzo; Tamura, Masato; Matsui, Hirofumi; Matsusaki, Michiya; Akashi, Mitsuru; Nakamura, Chikashi

    2014-01-01

    Graphical abstract: - Highlights: • We developed a method to measure cell adhesion force by detaching cell using an arrowhead nanoneedle and AFM. • A nanofilm consisting of fibronectin and gelatin was formed on cell surface to reinforce the cell cortex. • By the nanofilm lamination, detachment efficiencies of strongly adherent cell lines were improved markedly. - Abstract: The properties of substrates and extracellular matrices (ECM) are important factors governing the functions and fates of mammalian adherent cells. For example, substrate stiffness often affects cell differentiation. At focal adhesions, clustered–integrin bindings link cells mechanically to the ECM. In order to quantitate the affinity between cell and substrate, the cell adhesion force must be measured for single cells. In this study, forcible detachment of a single cell in the vertical direction using AFM was carried out, allowing breakage of the integrin–substrate bindings. An AFM tip was fabricated into an arrowhead shape to detach the cell from the substrate. Peak force observed in the recorded force curve during probe retraction was defined as the adhesion force, and was analyzed for various types of cells. Some of the cell types adhered so strongly that they could not be picked up because of plasma membrane breakage by the arrowhead probe. To address this problem, a technique to reinforce the cellular membrane with layer-by-layer nanofilms composed of fibronectin and gelatin helped to improve insertion efficiency and to prevent cell membrane rupture during the detachment process, allowing successful detachment of the cells. This method for detaching cells, involving cellular membrane reinforcement, may be beneficial for evaluating true cell adhesion forces in various cell types

  16. Study of Adhesion Interaction Using Atomic Force Microscopy

    Science.gov (United States)

    Grybos, J.; Pyka-Fosciak, G.; Lebed, K.; Lekka, M.; Stachura, Z.; Styczeñ, J.

    2003-05-01

    An atomic force microscope is a useful tool to study the interaction forces at molecular level. In particular the atomic force microscope can measure an unbinding force needed to separate the two single molecule complexes. Recent studies have shown that such unbinding force depends linearly on the logarithm of the applied loading rate, defined as a product of scanning velocity and the spring constant characterizing the investigated system (cantilever vs. surface). This dependence can be used to study the energy landscape shape of a molecular complex by the estimation of energy barrier locations and the related dissociation rates. In the present work the complex consisting of ethylene(di)aminetetraacetic acid and the bovine serum albumin was measured. The dependence between the unbinding force and the logarithm of the loading rate was linear. Using the Bell model describing the dissociation of the above molecules caused by the action of the external bond breaking force, two parameters were estimated: the dissociation rate and the position of the energy barrier needed to overcome during a transition from a bound to unbound state. The obtained results are similar to those obtained for a typical ligand--receptor interaction.

  17. Study of the time effect on the strength of cell-cell adhesion force by a novel nano-picker

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yajing, E-mail: shen@robo.mein.naogya-u.ac.jp [Dept. of Micro-Nano Systems Engineering, Nagoya University, Nagoya 464-8603 (Japan); Nakajima, Masahiro [Center for Micro-Nano Mechatronics, Nagoya University, Nagoya 464-8603 (Japan); Kojima, Seiji; Homma, Michio [Division of Biological Science, Nagoya University, Nagoya 464-8603 (Japan); Fukuda, Toshio [Dept. of Micro-Nano Systems Engineering, Nagoya University, Nagoya 464-8603 (Japan); Center for Micro-Nano Mechatronics, Nagoya University, Nagoya 464-8603 (Japan)

    2011-06-03

    Highlights: {yields} A nano-picker is developed for single cell adhesion force measurement. {yields} The adhesion of picker-cell has no influence to the cell-cell measurement result. {yields} Cell-cell adhesion force has a rise at the first few minutes and then becomes constant. -- Abstract: Cell's adhesion is important to cell's interaction and activates. In this paper, a novel method for cell-cell adhesion force measurement was proposed by using a nano-picker. The effect of the contact time on the cell-cell adhesion force was studied. The nano-picker was fabricated from an atomic force microscopy (AFM) cantilever by nano fabrication technique. The cell-cell adhesion force was measured based on the deflection of the nano-picker beam. The result suggests that the adhesion force between cells increased with the increasing of contact time at the first few minutes. After that, the force became constant. This measurement methodology was based on the nanorobotic manipulation system inside an environmental scanning electron microscope. It can realize both the observation and manipulation of a single cell at nanoscale. The quantitative and precise cell-cell adhesion force result can be obtained by this method. It would help us to understand the single cell interaction with time and would benefit the research in medical and biological fields potentially.

  18. Bacterial adhesion forces to Ag-impregnated contact lens cases and transmission to contact lenses.

    Science.gov (United States)

    Qu, Wenwen; Busscher, Henk J; van der Mei, Henny C; Hooymans, Johanna M M

    2013-03-01

    To measure adhesion forces of Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens to a rigid contact lens (CL), standard polypropylene, and Ag-impregnated lens cases using atomic force microscopy and determine bacterial transmission from lens case to CL. Adhesion forces of bacterial strains to Ag-impregnated and polypropylene lens cases and a rigid CL were measured using atomic force microscopy. Adhesion forces were used to calculate Weibull distributions, from which transmission probabilities from lens case to CL were derived. Transmission probabilities were compared with actual transmission of viable bacteria from a lens case to the CL in 0.9% NaCl and in an antimicrobial lens care solution. Bacterial transmission probabilities from polypropylene lens cases based on force analysis coincided well for all strains with actual transmission in 0.9% NaCl. Bacterial adhesion forces on Ag-impregnated lens cases were much smaller than that on polypropylene and CLs, yielding a high probability of transmission. Comparison with actual bacterial transmission indicated bacterial killing due to Ag ions during colony-forming unit transmission from an Ag-impregnated lens case, especially for P. aeruginosa. Transmission of viable bacteria from Ag-impregnated lens cases could be further decreased by use of an antimicrobial lens care solution instead of 0.9% NaCl. Bacterial transmission probabilities are higher from Ag-impregnated lens cases than from polypropylene lens cases because of small adhesion forces, but this is compensated for by enhanced bacterial killing due to Ag impregnation, especially when in combination with an antimicrobial lens care solution. This calls for a balanced combination of antimicrobial lens care solutions and surface properties of a lens case and CL.

  19. Insights into the relation between adhesion force and chalcopyrite-bioleaching by Acidithiobacillus ferrooxidans.

    Science.gov (United States)

    Zhu, Jianyu; Wang, Qianfen; Zhou, Shuang; Li, Qian; Gan, Min; Jiang, Hao; Qin, Wenqing; Liu, Xueduan; Hu, Yuehua; Qiu, Guanzhou

    2015-02-01

    This paper presents a study on the relation between bacterial adhesion force and bioleaching rate of chalcopyrite, which sheds light on the influence of interfacial interaction on bioleaching behavior. In our research, Acidithiobacillus ferrooxidans (A. ferrooxidans) were adapted to grow with FeSO4 · 7H2O, element sulfur or chalcopyrite. Then, surface properties of Acidithiobacillus ferrooxidans and chalcopyrite were analyzed by contact angle, zeta potential and Fourier transform infrared spectroscopy (FTIR). Adhesion force between bacteria and chalcopyrite was measured by atomic force microscopy (AFM). Attachment and bioleaching behaviors were also monitored. The results showed that A. ferrooxidans adapted with chalcopyrite exhibited the strongest adhesion force to chalcopyrite and the highest bioleaching rate. Culture adapted with sulfur bacteria took second place and FeSO4 · 7H2O-adapted bacteria were the lowest. Bioleaching rate and bacterial attachment capacity were positively related to bacterial adhesion force, which is affected by the nature of energy source. According to this work, the attachment of bacteria to chalcopyrite surface is one of the most important aspects that influence the bioleaching process of chalcopyrite. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Competition of elastic and adhesive properties of carbon nanotubes anchored to atomic force microscopy tips

    International Nuclear Information System (INIS)

    Bernard, Charlotte; Marsaudon, Sophie; Boisgard, Rodolphe; Aime, Jean-Pierre

    2008-01-01

    In this paper we address the mechanical properties of carbon nanotubes anchored to atomic force microscopy (AFM) tips in a detailed analysis of experimental results and exhaustive description of a simple model. We show that volume elastic and surface adhesive forces both contribute to the dynamical AFM experimental signals. Their respective weights depend on the nanotube properties and on an experimental parameter: the oscillation amplitude. To quantify the elastic and adhesive contributions, a simple analytical model is used. It enables analytical expressions of the resonance frequency shift and dissipation that can be measured in the atomic force microscopy dynamical frequency modulation mode. It includes the nanotube adhesive contribution to the frequency shift. Experimental data for single-wall and multi-wall carbon nanotubes compare well to the model predictions for different oscillation amplitudes. Three parameters can be extracted: the distance necessary to unstick the nanotube from the surface and two spring constants corresponding to tube compression and to the elastic force required to overcome the adhesion force

  1. Influence of the forces on the adhesion behavior of graphite dust in HTGR

    International Nuclear Information System (INIS)

    Peng Wei; Sun Xiaokai; Zhang Tianqi; Yu Suyuan

    2015-01-01

    The behavior of the graphite dust is important to the safety of High Temperature Gas-cooled Reactors. The present study focuses on the forces which make the graphite dust attach or detach from the surface in HTGR. The effect of graphite dust size, the fluid velocity and the surface energy between the particles and the substrate were investigated. The result showed that van der Waals adhesion force is the main factors affecting the dust attach on the surface, the gravity force and the electrostatic force were much smaller than it. For small particles, both the aerodynamic lift and drag are smaller than van der Waals adhesion force. While for the large particles, the coupled effects of aerodynamic lift and drag can make the dust detach from the substrate easier. Both the aerodynamic lift and drag forces will increase quickly as the fluid velocity increases. The surface energy is an important parameter for van der Waals adhesion force, which will decrease as the surface energy decreases. (author)

  2. Atomic force microscopic investigation of commercial pressure sensitive adhesives for forensic analysis.

    Science.gov (United States)

    Canetta, Elisabetta; Adya, Ashok K

    2011-07-15

    Pressure sensitive adhesive (PSA), such as those used in packaging and adhesive tapes, are very often encountered in forensic investigations. In criminal activities, packaging tapes may be used for sealing packets containing drugs, explosive devices, or questioned documents, while adhesive and electrical tapes are used occasionally in kidnapping cases. In this work, the potential of using atomic force microscopy (AFM) in both imaging and force mapping (FM) modes to derive additional analytical information from PSAs is demonstrated. AFM has been used to illustrate differences in the ultrastructural and nanomechanical properties of three visually distinguishable commercial PSAs to first test the feasibility of using this technique. Subsequently, AFM was used to detect nanoscopic differences between three visually indistinguishable PSAs. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  3. Characterisation of cellular adhesion reinforcement by multiple bond force spectroscopy in alveolar epithelial cells.

    Science.gov (United States)

    Nguyen, Ngoc-Minh; Angely, Christelle; Andre Dias, Sofia; Planus, Emmanuelle; Filoche, Marcel; Pelle, Gabriel; Louis, Bruno; Isabey, Daniel

    2017-07-01

    Integrin-mediated adhesion is a key process by which cells physically connect with their environment, and express sensitivity and adaptation through mechanotransduction. A critical step of cell adhesion is the formation of the first bonds which individually generate weak contacts (∼tens pN) but can sustain thousand times higher forces (∼tens nN) when associated. We propose an experimental validation by multiple bond force spectroscopy (MFS) of a stochastic model predicting adhesion reinforcement permitted by non-cooperative, multiple bonds on which force is homogeneously distributed (called parallel bond configuration). To do so, spherical probes (diameter: 6.6 μm), specifically coated by RGD-peptide to bind integrins, are used to statically indent and homogenously stretch the multiple bonds created for short contact times (2 s) between the bead and the surface of epithelial cells (A549). Using different separation speeds (v = 2, 5, 10 μm/s) and measuring cellular Young's modulus as well as the local stiffness preceding local rupture events, we obtain cell-by-cell the effective loading rates both at the global cell level and at the local level of individual constitutive bonds. Local rupture forces are in the range: f*=60-115 pN , whereas global rupture (detachment) forces reach F*=0.8-1.7 nN . Global and local rupture forces both exhibit linear dependencies with the effective loading rate, the slopes of these two linear relationships providing an estimate of the number of independent integrin bonds constituting the tested multiple bond structure (∼12). The MFS method enables to validate the reinforcement of integrin-mediated adhesion induced by the multiple bond configuration in which force is homogeneously distributed amongst parallel bonds. Local rupture events observed in the course of a spectroscopy manoeuver (MFS) lead to rupture force values considered in the literature as single-integrin bonds. Adhesion reinforcement permitted by the parallel

  4. Nanomechanical measurement of adhesion and migration of leukemia cells with phorbol 12-myristate 13-acetate treatment.

    Science.gov (United States)

    Zhou, Zhuo Long; Ma, Jing; Tong, Ming-Hui; Chan, Barbara Pui; Wong, Alice Sze Tsai; Ngan, Alfonso Hing Wan

    The adhesion and traction behavior of leukemia cells in their microenvironment is directly linked to their migration, which is a prime issue affecting the release of cancer cells from the bone marrow and hence metastasis. In assessing the effectiveness of phorbol 12-myristate 13-acetate (PMA) treatment, the conventional batch-cell transwell-migration assay may not indicate the intrinsic effect of the treatment on migration, since the treatment may also affect other cellular behavior, such as proliferation or death. In this study, the pN-level adhesion and traction forces between single leukemia cells and their microenvironment were directly measured using optical tweezers and traction-force microscopy. The effects of PMA on K562 and THP1 leukemia cells were studied, and the results showed that PMA treatment significantly increased cell adhesion with extracellular matrix proteins, bone marrow stromal cells, and human fibroblasts. PMA treatment also significantly increased the traction of THP1 cells on bovine serum albumin proteins, although the effect on K562 cells was insignificant. Western blots showed an increased expression of E-cadherin and vimentin proteins after the leukemia cells were treated with PMA. The study suggests that PMA upregulates adhesion and thus suppresses the migration of both K562 and THP1 cells in their microenvironment. The ability of optical tweezers and traction-force microscopy to measure directly pN-level cell-protein or cell-cell contact was also demonstrated.

  5. Adhesion forces in AFM of redox responsive polymer grafts: Effects of tip hydrophilicity

    NARCIS (Netherlands)

    Feng, Xueling; Kieviet, B.D.; Song, Jing; Schön, Peter Manfred; Vancso, Gyula J.

    2014-01-01

    The adherence between silicon nitride AFM tips and redox-active poly(ferrocenylsilanes) (PFS) grafts ongold was investigated by electrochemical AFM force spectroscopy. Before the adhesion measurementssilicon nitride AFM probes were cleaned with organic solvents (acetone and ethanol) or piranha

  6. Quantifying cellular mechanics and adhesion in renal tubular injury using single cell force spectroscopy.

    Science.gov (United States)

    Siamantouras, Eleftherios; Hills, Claire E; Squires, Paul E; Liu, Kuo-Kang

    2016-05-01

    Tubulointerstitial fibrosis represents the major underlying pathology of diabetic nephropathy where loss of cell-to-cell adhesion is a critical step. To date, research has predominantly focussed on the loss of cell surface molecular binding events that include altered protein ligation. In the current study, atomic force microscopy single cell force spectroscopy (AFM-SCFS) was used to quantify changes in cellular stiffness and cell adhesion in TGF-β1 treated kidney cells of the human proximal tubule (HK2). AFM indentation of TGF-β1 treated HK2 cells showed a significant increase (42%) in the elastic modulus (stiffness) compared to control. Fluorescence microscopy confirmed that increased cell stiffness is accompanied by reorganization of the cytoskeleton. The corresponding changes in stiffness, due to F-actin rearrangement, affected the work of detachment by changing the separation distance between two adherent cells. Overall, our novel data quantitatively demonstrate a correlation between cellular elasticity, adhesion and early morphologic/phenotypic changes associated with tubular injury. Diabetes affects many patients worldwide. One of the long term problems is diabetic nephropathy. Here, the authors utilized atomic force microscopy single cell force spectroscopy (AFM- SCFS) to study cellular stiffness and cell adhesion after TGF1 treatment in human proximal tubule kidney cells. The findings would help further understand the overall disease mechanism in diabetic patients. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Investigation of adhesion and mechanical properties of human glioma cells by single cell force spectroscopy and atomic force microscopy.

    Science.gov (United States)

    Andolfi, Laura; Bourkoula, Eugenia; Migliorini, Elisa; Palma, Anita; Pucer, Anja; Skrap, Miran; Scoles, Giacinto; Beltrami, Antonio Paolo; Cesselli, Daniela; Lazzarino, Marco

    2014-01-01

    Active cell migration and invasion is a peculiar feature of glioma that makes this tumor able to rapidly infiltrate into the surrounding brain tissue. In our recent work, we identified a novel class of glioma-associated-stem cells (defined as GASC for high-grade glioma--HG--and Gasc for low-grade glioma--LG) that, although not tumorigenic, act supporting the biological aggressiveness of glioma-initiating stem cells (defined as GSC for HG and Gsc for LG) favoring also their motility. Migrating cancer cells undergo considerable molecular and cellular changes by remodeling their cytoskeleton and cell interactions with surrounding environment. To get a better understanding about the role of the glioma-associated-stem cells in tumor progression, cell deformability and interactions between glioma-initiating stem cells and glioma-associated-stem cells were investigated. Adhesion of HG/LG-cancer cells on HG/LG-glioma-associated stem cells was studied by time-lapse microscopy, while cell deformability and cell-cell adhesion strengths were quantified by indentation measurements by atomic force microscopy and single cell force spectroscopy. Our results demonstrate that for both HG and LG glioma, cancer-initiating-stem cells are softer than glioma-associated-stem cells, in agreement with their neoplastic features. The adhesion strength of GSC on GASC appears to be significantly lower than that observed for Gsc on Gasc. Whereas, GSC spread and firmly adhere on Gasc with an adhesion strength increased as compared to that obtained on GASC. These findings highlight that the grade of glioma-associated-stem cells plays an important role in modulating cancer cell adhesion, which could affect glioma cell migration, invasion and thus cancer aggressiveness. Moreover this work provides evidence about the importance of investigating cell adhesion and elasticity for new developments in disease diagnostics and therapeutics.

  8. Integrin and glycocalyx mediated contributions to cell adhesion identified by single cell force spectroscopy

    International Nuclear Information System (INIS)

    Boettiger, D; Wehrle-Haller, B

    2010-01-01

    The measurement of cell adhesion using single cell force spectroscopy methods was compared with earlier methods for measuring cell adhesion. This comparison provided a means and rationale for separating components of the measurement retract curve that were due to interactions between the substrate and the glycocalyx, and interactions that were due to cell surface integrins binding to a substrate-bound ligand. The glycocalyx adhesion was characterized by multiple jumps with dispersed jump sizes that extended from 5 to 30 μm from the origin. The integrin mediated adhesion was represented by the F max (maximum detachment force), was generally within the first 5 μm and commonly detached with a single rupture cascade. The integrin peak (F max ) increases with time and the rate of increase shows large cell to cell variability with a peak ∼ 50 nN s -1 and an average rate of increase of 75 pN s -1 . This is a measure of the rate of increase in the number of adhesive integrin-ligand bonds/cell as a function of contact time.

  9. An in vitro correlation of mechanical forces and metastatic capacity

    International Nuclear Information System (INIS)

    Indra, Indrajyoti; Undyala, Vishnu; Kandow, Casey; Thirumurthi, Umadevi; Beningo, Karen A; Dembo, Micah

    2011-01-01

    Mechanical forces have a major influence on cell migration and are predicted to significantly impact cancer metastasis, yet this idea is currently poorly defined. In this study we have asked if changes in traction stress and migratory properties correlate with the metastatic progression of tumor cells. For this purpose, four murine breast cancer cell lines derived from the same primary tumor, but possessing increasing metastatic capacity, were tested for adhesion strength, traction stress, focal adhesion organization and for differential migration rates in two-dimensional and three-dimensional environments. Using traction force microscopy (TFM), we were surprised to find an inverse relationship between traction stress and metastatic capacity, such that force production decreased as the metastatic capacity increased. Consistent with this observation, adhesion strength exhibited an identical profile to the traction data. A count of adhesions indicated a general reduction in the number as metastatic capacity increased but no difference in the maturation as determined by the ratio of nascent to mature adhesions. These changes correlated well with a reduction in active beta-1 integrin with increasing metastatic ability. Finally, in two dimensions, wound healing, migration and persistence were relatively low in the entire panel, maintaining a downward trend with increasing metastatic capacity. Why metastatic cells would migrate so poorly prompted us to ask if the loss of adhesive parameters in the most metastatic cells indicated a switch to a less adhesive mode of migration that would only be detected in a three-dimensional environment. Indeed, in three-dimensional migration assays, the most metastatic cells now showed the greatest linear speed. We conclude that traction stress, adhesion strength and rate of migration do indeed change as tumor cells progress in metastatic capacity and do so in a dimension-sensitive manner

  10. Friction and Adhesion Forces of Bacillus thuringiensis Spores on Planar Surfaces in Atmospheric Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kweon, Hyojin [Georgia Inst. of Technology, Atlanta, GA (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States); Tsouris, Costas [Georgia Inst. of Technology, Atlanta, GA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2011-11-07

    The kinetic friction force and the adhesion force of Bacillus thuringiensis spores on planar surfaces in atmospheric systems were studied using atomic force microscopy. The influence of relative humidity (RH) on these forces varied for different surface properties including hydrophobicity, roughness, and surface charge. The friction force of the spore was greater on a rougher surface than on mica, which is atomically flat. As RH increases, the friction force of the spores decreases on mica whereas it increases on rough surfaces. The influence of RH on the interaction forces between hydrophobic surfaces is not as strong as for hydrophilic surfaces. The friction force of the spore is linear to the sum of the adhesion force and normal load on the hydrophobic surface. In conclusion, the poorly defined surface structure of the spore and the adsorption of contaminants from the surrounding atmosphere are believed to cause a discrepancy between the calculated and measured adhesion forces.

  11. Exploring the elasticity and adhesion behavior of cardiac fibroblasts by atomic force microscopy indentation

    Energy Technology Data Exchange (ETDEWEB)

    Codan, B.; Del Favero, G. [Department of Engineering and Architecture, University of Trieste (Italy); Martinelli, V. [Department of Engineering and Architecture, University of Trieste (Italy); International Center for Genetic Engineering and Biotechnology, Trieste (Italy); Long, C.S.; Mestroni, L. [University of Colorado Cardiovascular Institute, University of Colorado Denver, Aurora, CO (United States); Sbaizero, O., E-mail: sbaizero@units.it [Department of Engineering and Architecture, University of Trieste (Italy)

    2014-07-01

    AFM was used to collect the whole force–deformation cell curves. They provide both the elasticity and adhesion behavior of mouse primary cardiac fibroblasts. To confirm the hypothesis that a link exists between the membrane receptors and the cytoskeletal filaments causing therefore changing in both elasticity and adhesion behavior, actin-destabilizing Cytochalsin D was administrated to the fibroblasts. From immunofluorescence observation and AFM loading/unloading curves, cytoskeletal reorganization as well as a change in the elasticity and adhesion was indeed observed. Elasticity of control fibroblasts is three times higher than that for fibroblasts treated with 0.5 μM Cytochalasin. Moreover, AFM loading–unloading curves clearly show the different mechanical behavior of the two different cells analyzed: (i) for control cells the AFM cantilever rises during the dwell time while cells with Cytochalasin fail to show such an active resistance; (ii) the maximum force to deform control cells is quite higher and as far as adhesion is concern (iii) the maximum separation force, detachment area and the detachment process time are much larger for control compared to the Cytochalasin treated cells. Therefore, alterations in the cytoskeleton suggest that a link must exist between the membrane receptors and the cytoskeletal filaments beneath the cellular surface and inhibition of actin polymerization has effects on the whole cell mechanical behavior as well as adhesion. - Highlights: • The whole AFM force–deformation cell curves were analyzed. • They provide information on both the elasticity and adhesion behavior. • Actin-destabilizing Cytochalasin D was administrated to the fibroblasts. • Change in elasticity and adhesion was ascribed to cytoskeletal reorganization. • A link exists between the membrane receptors and the cytoskeletal filaments.

  12. Exploring the elasticity and adhesion behavior of cardiac fibroblasts by atomic force microscopy indentation

    International Nuclear Information System (INIS)

    Codan, B.; Del Favero, G.; Martinelli, V.; Long, C.S.; Mestroni, L.; Sbaizero, O.

    2014-01-01

    AFM was used to collect the whole force–deformation cell curves. They provide both the elasticity and adhesion behavior of mouse primary cardiac fibroblasts. To confirm the hypothesis that a link exists between the membrane receptors and the cytoskeletal filaments causing therefore changing in both elasticity and adhesion behavior, actin-destabilizing Cytochalsin D was administrated to the fibroblasts. From immunofluorescence observation and AFM loading/unloading curves, cytoskeletal reorganization as well as a change in the elasticity and adhesion was indeed observed. Elasticity of control fibroblasts is three times higher than that for fibroblasts treated with 0.5 μM Cytochalasin. Moreover, AFM loading–unloading curves clearly show the different mechanical behavior of the two different cells analyzed: (i) for control cells the AFM cantilever rises during the dwell time while cells with Cytochalasin fail to show such an active resistance; (ii) the maximum force to deform control cells is quite higher and as far as adhesion is concern (iii) the maximum separation force, detachment area and the detachment process time are much larger for control compared to the Cytochalasin treated cells. Therefore, alterations in the cytoskeleton suggest that a link must exist between the membrane receptors and the cytoskeletal filaments beneath the cellular surface and inhibition of actin polymerization has effects on the whole cell mechanical behavior as well as adhesion. - Highlights: • The whole AFM force–deformation cell curves were analyzed. • They provide information on both the elasticity and adhesion behavior. • Actin-destabilizing Cytochalasin D was administrated to the fibroblasts. • Change in elasticity and adhesion was ascribed to cytoskeletal reorganization. • A link exists between the membrane receptors and the cytoskeletal filaments

  13. A new technical approach to quantify cell-cell adhesion forces by AFM

    International Nuclear Information System (INIS)

    Puech, Pierre-Henri; Poole, Kate; Knebel, Detlef; Muller, Daniel J.

    2006-01-01

    Cell-cell adhesion is a complex process that is involved in the tethering of cells, cell-cell communication, tissue formation, cell migration and the development and metastasis of tumors. Given the heterogeneous and complex nature of cell surfaces it has previously proved difficult to characterize individual cell-cell adhesion events. Force spectroscopy, using an atomic force microscope, is capable of resolving such individual cell-cell binding events, but has previously been limited in its application due to insufficient effective pulling distances. Extended pulling range is critical in studying cell-cell interactions due to the potential for large cell deformations. Here we describe an approach to such experiments, where the sample stage can be moved 100 μm in the z-direction, by closed loop, linearized piezo elements. Such an approach enables an increase in pulling distance sufficient for the observation of long-distance cell-unbinding events without reducing the imaging capabilities of the atomic force microscope. The atomic force microscope head and the piezo-driven sample stage are installed on an inverted optical microscope fitted with a piezo-driven objective, to allow the monitoring of cell morphology by conventional light microscopy, concomitant with force spectroscopy measurements. We have used the example of the WM115 melanoma cell line binding to human umbilical vein endothelial cells to demonstrate the capabilities of this system and the necessity for such an extended pulling range when quantifying cell-cell adhesion events

  14. Atomic force microscopy measurements of bacterial adhesion and biofilm formation onto clay-sized particles

    Science.gov (United States)

    Huang, Qiaoyun; Wu, Huayong; Cai, Peng; Fein, Jeremy B.; Chen, Wenli

    2015-01-01

    Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of −3.0 ± 0.4 nN and −330 ± 43 aJ (10−18 J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions. PMID:26585552

  15. Molecular Velcro constructed from polymer loop brushes showing enhanced adhesion force

    Science.gov (United States)

    Zhou, Tian; Han, Biao; Han, Lin; Li, Christopher; Department of Materials Science; Engineering Team; School of Biomedical Engineering, Science; Health Systems Team

    2015-03-01

    Molecular Velcro is commonly seen in biological systems as the formation of strong physical entanglement at molecular scale could induce strong adhesion, which is crucial to many biological processes. To mimic this structure, we designed, and fabricated polymer loop brushes using polymer single crystals with desired surface functionality and controlled chain folding. Compared with reported loop brushes fabricated using triblock copolymers, the present loop bushes have precise loop sizes, loop grafting density, and well controlled tethering locations on the solid surface. Atomic force microscopy-based force spectroscopy measurements using a polymer chain coated probe reveal that the adhesion force are significantly enhanced on the loop brush surface as compared with its single-strand counterpart. This study directly shows the effect of polymer brush conformation on their properties, and suggests a promising strategy for advanced polymer surface design.

  16. Effect of low temperature oxygen plasma treatment on microstructure and adhesion force of graphene

    Science.gov (United States)

    Zhu, Jun; Deng, Heijun; Xue, Wei; Wang, Quan

    2018-01-01

    Graphene has attracted strong attention due to its unique mechanical, electrical, thermal and magnetic properties. In this work, we investigate the effect of low temperature oxygen plasma treatment on microstructure and adhesion force of single-layer graphene (SLG). Low temperature oxygen plasma is used to treat SLG grown by chemical vapor deposition through varying the exposure time. Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy are utilized to identify changes before and after treatment. Raman spectra of treated graphene reveal that peak intensity of the characteristic D and D' peaks increase. Meanwhile, degradation of the G and 2D peaks in X-ray photoelectron spectroscopy indicates that abundant Csbnd OH and Cdbnd O functional groups are introduced into graphene after treatment. AFM investigation shows that surface roughness and adhesion force of treated graphene increase significantly firstly and then slowly. Therefore, this work would offer a practical route to improve the performance of graphene-based devices.

  17. Orthodontic traction of impacted canine using magnet: a case report

    OpenAIRE

    Li, Larry CF; Wong, Ricky WK; King, Nigel M

    2008-01-01

    ABSTRACT: A 15 year and 1 month old Chinese female with palatally impacted upper left canine was successfully treated with an upper removable appliance with a magnet incorporated to provide orthodontic traction force. This case report indicates the possibility of using magnetic force as a safe, effective and comfortable way for orthodontic traction.

  18. Osteopontin Reduces the Adhesion Force of Dental Bacteria Without Blocking Bacterial Cell Surface Glycoconjugates

    DEFF Research Database (Denmark)

    Kristensen, Mathilde Frost; Zeng, Guanghong; Neu, Thomas R.

    2017-01-01

    . paracasei, and lectins VGA and WGA to S. mitis. Immobilized bacteria were incubated with these lectins in the presence and absence of OPN. For each combination, 12 confocal images were acquired with fixed microscope settings, and average fluorescence intensities were determined. Experiments were performed......The bovine milk protein osteopontin (OPN) has been shown to reduce the adhesion of oral bacteria to saliva-coated surfaces, which reduces biofilm formation and may contribute to caries control. We now quantified the effect of OPN (Lacprodan OPN-10) treatment on the adhesion force of Lactobacillus...... and after OPN treatment. Adhesion energy was found to be reduced by 94% for L. paracasei and 61% for A. naeslundii (pbacteria was screened. Lectins BanLec, ConA, VGA and WGA bound well to A. naeslundii, lectins ABA and HPA to L...

  19. Surface force measurements and simulations of mussel-derived peptide adhesives on wet organic surfaces.

    Science.gov (United States)

    Levine, Zachary A; Rapp, Michael V; Wei, Wei; Mullen, Ryan Gotchy; Wu, Chun; Zerze, Gül H; Mittal, Jeetain; Waite, J Herbert; Israelachvili, Jacob N; Shea, Joan-Emma

    2016-04-19

    Translating sticky biological molecules-such as mussel foot proteins (MFPs)-into synthetic, cost-effective underwater adhesives with adjustable nano- and macroscale characteristics requires an intimate understanding of the glue's molecular interactions. To help facilitate the next generation of aqueous adhesives, we performed a combination of surface forces apparatus (SFA) measurements and replica-exchange molecular dynamics (REMD) simulations on a synthetic, easy to prepare, Dopa-containing peptide (MFP-3s peptide), which adheres to organic surfaces just as effectively as its wild-type protein analog. Experiments and simulations both show significant differences in peptide adsorption on CH3-terminated (hydrophobic) and OH-terminated (hydrophilic) self-assembled monolayers (SAMs), where adsorption is strongest on hydrophobic SAMs because of orientationally specific interactions with Dopa. Additional umbrella-sampling simulations yield free-energy profiles that quantitatively agree with SFA measurements and are used to extract the adhesive properties of individual amino acids within the context of MFP-3s peptide adhesion, revealing a delicate balance between van der Waals, hydrophobic, and electrostatic forces.

  20. Retinal Changes Induced by Epiretinal Tangential Forces

    Directory of Open Access Journals (Sweden)

    Mario R. Romano

    2015-01-01

    Full Text Available Two kinds of forces are active in vitreoretinal traction diseases: tangential and anterior-posterior forces. However, tangential forces are less characterized and classified in literature compared to the anterior-posterior ones. Tangential epiretinal forces are mainly due to anomalous posterior vitreous detachment (PVD, vitreoschisis, vitreopapillary adhesion (VPA, and epiretinal membranes (ERMs. Anomalous PVD plays a key role in the formation of the tangential vectorial forces on the retinal surface as consequence of gel liquefaction (synchysis without sufficient and fast vitreous dehiscence at the vitreoretinal interface. The anomalous and persistent adherence of the posterior hyaloid to the retina can lead to vitreomacular/vitreopapillary adhesion or to a formation of avascular fibrocellular tissue (ERM resulting from the proliferation and transdifferentiation of hyalocytes resident in the cortical vitreous remnants after vitreoschisis. The right interpretation of the forces involved in the epiretinal tangential tractions helps in a better definition of diagnosis, progression, prognosis, and surgical outcomes of vitreomacular interfaces.

  1. Quantifying bacterial adhesion on antifouling polymer brushes via single-cell force spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Janel, S.; de los Santos Pereira, Andres; Bruns, M.; Lafont, F.

    2015-01-01

    Roč. 6, č. 31 (2015), s. 5740-5751 ISSN 1759-9954 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : antifouling polymer brushes * single-cell force spectroscopy * bacterial adhesion Subject RIV: BO - Biophysics Impact factor: 5.687, year: 2015

  2. Analysis of long- and short-range contribution to adhesion work in cardiac fibroblasts: An atomic force microscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Sbaizero, O., E-mail: sbaizero@units.it [Department of Engineering and Architecture, University of Trieste (Italy); University of Colorado Cardiovascular Institute, University of Colorado Denver, Aurora (United States); DelFavero, G. [Department of Engineering and Architecture, University of Trieste (Italy); Martinelli, V. [International Center for Genetic Engineering and Biotechnology, Trieste (Italy); Long, C.S.; Mestroni, L. [University of Colorado Cardiovascular Institute, University of Colorado Denver, Aurora (United States)

    2015-04-01

    Atomic force microscopy (AFM) for single-cell force spectroscopy (SCFS) and Poisson statistic were used to analyze the detachment work recorded during the removal of gold-covered microspheres from cardiac fibroblasts. The effect of Cytochalasin D, a disruptor of the actin cytoskeleton, on cell adhesion was also tested. The adhesion work was assessed using a Poisson analysis also derived from single-cell force spectroscopy retracting curves. The use of Poisson analysis to get adhesion work from AFM curves is quite a novel method, and in this case, proved to be effective to study the short-range and long-range contributions to the adhesion work. This method avoids the difficult identification of minor peaks in the AFM retracting curves by creating what can be considered an average adhesion work. Even though the effect of actin depolymerisation is well documented, its use revealed that control cardiac fibroblasts (CT) exhibit a work of adhesion at least 5 times higher than that of the Cytochalasin treated cells. However, our results indicate that in both cells short-range and long-range contributions to the adhesion work are nearly equal and the same heterogeneity index describes both cells. Therefore, we infer that the different adhesion behaviors might be explained by the presence of fewer membrane adhesion molecules available at the AFM tip–cell interface under circumstances where the actin cytoskeleton has been disrupted. - Highlights: • AFM force–deformation curve was used to characterize the cardiac fibroblast adhesion behavior. • The amount and nature of adhesion were assessed using a Poisson analysis applied to the AFM curve. • The work of adhesion for control cells was about four times higher than that of the Cyt-D treated cells. • Short- and long-range contributions to adhesion are nearly equal for both control and treated cells.

  3. Normally Oriented Adhesion versus Friction Forces in Bacterial Adhesion to Polymer-Brush Functionalized Surfaces Under Fluid Flow

    NARCIS (Netherlands)

    Swartjes, Jan J. T. M.; Veeregowda, Deepak H.; van der Mei, Henny C.; Busscher, Henk J.; Sharma, Prashant K.

    2014-01-01

    Bacterial adhesion is problematic in many diverse applications. Coatings of hydrophilic polymer chains in a brush configuration reduce bacterial adhesion by orders of magnitude, but not to zero. Here, the mechanism by which polymer-brush functionalized surfaces reduce bacterial adhesion from a

  4. Mapping molecular adhesion sites inside SMIL coated capillaries using atomic force microscopy recognition imaging

    Energy Technology Data Exchange (ETDEWEB)

    Leitner, Michael [Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz (Austria); Stock, Lorenz G. [Division of Chemistry and Bioanalytics, Department of Molecular Biology, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Christian Doppler Laboratory for Innovative Tools for the Characterization of Biosimilars, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Traxler, Lukas [Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz (Austria); Leclercq, Laurent [Institut des Biomolécules Max Mousseron (IBMM, UMR 5247, CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier), Place Eugène Bataillon, CC 1706, 34095 Montpellier (France); Bonazza, Klaus; Friedbacher, Gernot [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164, 1060 Vienna (Austria); Cottet, Hervé [Institut des Biomolécules Max Mousseron (IBMM, UMR 5247, CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier), Place Eugène Bataillon, CC 1706, 34095 Montpellier (France); Stutz, Hanno [Division of Chemistry and Bioanalytics, Department of Molecular Biology, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Christian Doppler Laboratory for Innovative Tools for the Characterization of Biosimilars, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Ebner, Andreas, E-mail: andreas.ebner@jku.at [Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz (Austria)

    2016-08-03

    Capillary zone electrophoresis (CZE) is a powerful analytical technique for fast and efficient separation of different analytes ranging from small inorganic ions to large proteins. However electrophoretic resolution significantly depends on the coating of the inner capillary surface. High technical efforts like Successive Multiple Ionic Polymer Layer (SMIL) generation have been taken to develop stable coatings with switchable surface charges fulfilling the requirements needed for optimal separation. Although the performance can be easily proven in normalized test runs, characterization of the coating itself remains challenging. Atomic force microscopy (AFM) allows for topographical investigation of biological and analytical relevant surfaces with nanometer resolution and yields information about the surface roughness and homogeneity. Upgrading the scanning tip to a molecular biosensor by adhesive molecules (like partly inverted charged molecules) allows for performing topography and recognition imaging (TREC). As a result, simultaneously acquired sample topography and adhesion maps can be recorded. We optimized this technique for electrophoresis capillaries and investigated the charge distribution of differently composed and treated SMIL coatings. By using the positively charged protein avidin as a single molecule sensor, we compared these SMIL coatings with respect to negative charges, resulting in adhesion maps with nanometer resolution. The capability of TREC as a functional investigation technique at the nanoscale was successfully demonstrated. - Highlights: • SMIL coating allows generation of homogeneous ultra-flat surfaces. • Molecular electrostatic adhesion forces can be determined in the inner wall of CZE capillary with picoNewton accuracy. • Topographical images and simultaneously acquired adhesion maps yield morphological and chemical information at the nanoscale.

  5. Influence of tip indentation on the adhesive behavior of viscoelastic polydimethylsiloxane networks studied by atomic force microscopy

    NARCIS (Netherlands)

    Pickering, J.P.; Vancso, Gyula J.

    2001-01-01

    A commercial atomic force microscope (AFM) outfitted with a custom control and data acquisition system was used to investigate the adhesive nature of a viscoelastic polydimethylsiloxane (PDMS) network. Due to the complex dependence of the adhesion of this sample on factors such as indentation,

  6. Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe

    Directory of Open Access Journals (Sweden)

    Juan V. Escobar

    2017-04-01

    Full Text Available We present a procedure to perform and interpret pull-off force measurements during the jump-off-contact process between a liquid drop and rough surfaces using a conventional atomic force microscope. In this method, a micrometric liquid mercury drop is attached to an AFM tipless cantilever to measure the force required to pull this drop off a rough surface. We test the method with two surfaces: a square array of nanometer-sized peaks commonly used for the determination of AFM tip sharpness and a multi-scaled rough diamond surface containing sub-micrometer protrusions. Measurements are carried out in a nitrogen atmosphere to avoid water capillary interactions. We obtain information about the average force of adhesion between a single peak or protrusion and the liquid drop. This procedure could provide useful microscopic information to improve our understanding of wetting phenomena on rough surfaces.

  7. Local elasticity and adhesion of nanostructures on Drosophila melanogaster wing membrane studied using atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Ryan, E-mail: rbwagner@purdue.edu [School of Mechanical Engineering, Purdue University, West Lafayette (United States); Brick Nanotechnology Center, Purdue University, West Lafayette (United States); Pittendrigh, Barry R. [Department of Entomology, University of Illinois, Champaign (United States); Raman, Arvind, E-mail: raman@purdue.edu [School of Mechanical Engineering, Purdue University, West Lafayette (United States); Brick Nanotechnology Center, Purdue University, West Lafayette (United States)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer We studied the wing membrane of Drosophila melanogaster with atomic force microscopy. Black-Right-Pointing-Pointer We report the structure, elasticity, and adhesion on the wing membrane in air and nitrogen environments. Black-Right-Pointing-Pointer Results provide insight into the nature of the wing membrane enabling the development of biomimetic surface and micro air vehicles. - Abstract: Insect wings have a naturally occurring, complex, functional, hierarchical microstructure and nanostructure, which enable a remarkably water-resistant and self-cleaning surface. Insect wings are used as a basis for engineering biomimetic materials; however, the material properties of these nanostructures such as local elastic modulus and adhesion are poorly understood. We studied the wings of the Canton-S strain of Drosophila melanogaster (hereafter referred to as Drosophila) with atomic force microscopy (AFM) to quantify the local material properties of Drosophila wing surface nanostructures. The wings are found to have a hierarchical structure of 10-20 {mu}m long, 0.5-1 {mu}m diameter hair, and at a much smaller scale, 100 nm diameter and 30-60 nm high bumps. The local properties of these nanoscale bumps were studied under ambient and dry conditions with force-volume AFM. The wing membrane was found to have a elastic modulus on the order of 1000 MPa and the work of adhesion between the probe and wing membrane surface was found to be on the order of 100 mJ/m{sup 2}, these properties are the same order of magnitude as common thermoplastic polymers such as polyethylene. The difference in work of adhesion between the nanoscale bump and membrane does not change significantly between ambient (relative humidity of 30%) or dry conditions. This suggests that the nanoscale bumps and the surrounding membrane are chemically similar and only work to increase hydrophobicity though surface roughening or the geometric lotus effect.

  8. Local elasticity and adhesion of nanostructures on Drosophila melanogaster wing membrane studied using atomic force microscopy

    International Nuclear Information System (INIS)

    Wagner, Ryan; Pittendrigh, Barry R.; Raman, Arvind

    2012-01-01

    Highlights: ► We studied the wing membrane of Drosophila melanogaster with atomic force microscopy. ► We report the structure, elasticity, and adhesion on the wing membrane in air and nitrogen environments. ► Results provide insight into the nature of the wing membrane enabling the development of biomimetic surface and micro air vehicles. - Abstract: Insect wings have a naturally occurring, complex, functional, hierarchical microstructure and nanostructure, which enable a remarkably water-resistant and self-cleaning surface. Insect wings are used as a basis for engineering biomimetic materials; however, the material properties of these nanostructures such as local elastic modulus and adhesion are poorly understood. We studied the wings of the Canton-S strain of Drosophila melanogaster (hereafter referred to as Drosophila) with atomic force microscopy (AFM) to quantify the local material properties of Drosophila wing surface nanostructures. The wings are found to have a hierarchical structure of 10–20 μm long, 0.5–1 μm diameter hair, and at a much smaller scale, 100 nm diameter and 30–60 nm high bumps. The local properties of these nanoscale bumps were studied under ambient and dry conditions with force-volume AFM. The wing membrane was found to have a elastic modulus on the order of 1000 MPa and the work of adhesion between the probe and wing membrane surface was found to be on the order of 100 mJ/m 2 , these properties are the same order of magnitude as common thermoplastic polymers such as polyethylene. The difference in work of adhesion between the nanoscale bump and membrane does not change significantly between ambient (relative humidity of 30%) or dry conditions. This suggests that the nanoscale bumps and the surrounding membrane are chemically similar and only work to increase hydrophobicity though surface roughening or the geometric lotus effect.

  9. Single-cell force spectroscopy as a technique to quantify human red blood cell adhesion to subendothelial laminin.

    Science.gov (United States)

    Maciaszek, Jamie L; Partola, Kostyantyn; Zhang, Jing; Andemariam, Biree; Lykotrafitis, George

    2014-12-18

    Single-cell force spectroscopy (SCFS), an atomic force microscopy (AFM)-based assay, enables quantitative study of cell adhesion while maintaining the native state of surface receptors in physiological conditions. Human healthy and pathological red blood cells (RBCs) express a large number of surface proteins which mediate cell-cell interactions, or cell adhesion to the extracellular matrix. In particular, RBCs adhere with high affinity to subendothelial matrix laminin via the basal cell adhesion molecule and Lutheran protein (BCAM/Lu). Here, we established SCFS as an in vitro technique to study human RBC adhesion at baseline and following biochemical treatment. Using blood obtained from healthy human subjects, we recorded adhesion forces from single RBCs attached to AFM cantilevers as the cell was pulled-off of substrates coated with laminin protein. We found that an increase in the overall cell adhesion measured via SCFS is correlated with an increase in the resultant total force measured on 1 µm(2) areas of the RBC membrane. Further, we showed that SCFS can detect significant changes in the adhesive response of RBCs to modulation of the cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) pathway. Lastly, we identified variability in the RBC adhesion force to laminin amongst the human subjects, suggesting that RBCs maintain diverse levels of active BCAM/Lu adhesion receptors. By using single-cell measurements, we established a powerful new method for the quantitative measurement of single RBC adhesion with specific receptor-mediated binding. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. THE TRACTION ELECTRIC OPERATION AND ITS EXPLOITATION ABILITIES

    Directory of Open Access Journals (Sweden)

    V. M. Bezruchenko

    2011-04-01

    Full Text Available The possibilities of asynchronous traction electric motor drive are considered at the certain coupling mass taking into account the coupling restrictions. A variant of using the regulation law for electric motor drive allowing realizing traction force more rationally is offered. The possibility of reaching the speeds to 220 km/h for electric locomotive DS3 is shown

  11. Soybean biodiesel consumption in agricultural tractor submitted the two forces in the traction bar; Consumo de biodiesel de soja em trator agricola submetido a duas forcas na barra de tracao

    Energy Technology Data Exchange (ETDEWEB)

    Camara, Felipe T. da [Universidade Federal do Ceara (UFC), Juazeiro do Norte, CE (Brazil)], E-mail: felipe.camara@cariri.ufc.br; Lopes, Afonso; Silva, Rouverson P. da; Oliveira, Melina C.J. de; Torres, Luma S. [Universidade Estadual Paulista (FCAV/UNESP), SP (Brazil). Fac. de Ciencias Agrarias e Veterinarias. Dept. de Engenharia Rural

    2009-07-01

    Due to the great development occurred in the world after the Second World War and the establishment of patterns of increasingly intense, the energy demand amounted to the point, putting at risk the non-renewable energy sources such as oil, coal minerals, among others, with growing interest in renewable energies, among which the biodiesel has been detached. In this sense, the present work had for objective to evaluate the fuel consumption of a tractor Valtra BM100 4x2 TDA, running with ethyl biodiesel from soybean filtered in seven mixture proportions mixed with the diesel, subject to two forces in the traction bar. The work was conducted in the Department of Rural Engineering of the Paulista State University (UNESP), Jaboticabal Campus, in an entirely randomized designed, in a factorial diagram 2 x 7, with three repetitions. The treatments were a combination for two forces in the traction bar (10 and 22 kN) and seven mixture proportions (B{sub 0}, B{sub 5}, B{sub 1}5, B{sub 2}5, B{sub 5}0, B{sub 7}5 e B{sub 1}00). The results showed that the addition of up to 25% biodiesel to diesel has not changed the fuel consumption, and the greatest force resulted in greater consumption volume and weight, and lower specific consumption, by better use of the power of the tractor. (author)

  12. Regression analysis of traction characteristics of traction fluids

    Science.gov (United States)

    Loewenthal, S. H.; Rohn, D. A.

    1983-01-01

    Traction data for Santotrac 50 and TDF-88 over a wide range of operating conditions were analyzed. An eight term correlation equation to predict the maximum traction coefficient and a six term correlation equation to predict the initial slope of the traction curve were developed. The slope correlation was corrected for size effect considering the compliance of the disks. The effects of different operating conditions on the traction performance of each traction fluid were studied. Both fluids exhibited a loss in traction with increases in spin, but the losses with the TDF-88 fluid were not as severe as those with Santotrac 50. Overall, both fluids exhibited similar performance, showing an increase in traction with contact pressure up to about 2.0 GPa, and a reduction in traction with higher surface speeds up to about 100 m/sec. The apparent stiffness of the traction contact, that is, film disk combination, increases with contact pressure and decreases with speed.

  13. Forced-rupture of cell-adhesion complexes reveals abrupt switch between two brittle states

    Science.gov (United States)

    Toan, Ngo Minh; Thirumalai, D.

    2018-03-01

    Cell adhesion complexes (CACs), which are activated by ligand binding, play key roles in many cellular functions ranging from cell cycle regulation to mediation of cell extracellular matrix adhesion. Inspired by single molecule pulling experiments using atomic force spectroscopy on leukocyte function-associated antigen-1 (LFA-1), expressed in T-cells, bound to intercellular adhesion molecules (ICAM), we performed constant loading rate (rf) and constant force (F) simulations using the self-organized polymer model to describe the mechanism of ligand rupture from CACs. The simulations reproduce the major experimental finding on the kinetics of the rupture process, namely, the dependence of the most probable rupture forces (f*s) on ln rf (rf is the loading rate) exhibits two distinct linear regimes. The first, at low rf, has a shallow slope, whereas the slope at high rf is much larger, especially for a LFA-1/ICAM-1 complex with the transition between the two occurring over a narrow rf range. Locations of the two transition states (TSs) extracted from the simulations show an abrupt change from a high value at low rf or constant force, F, to a low value at high rf or F. This unusual behavior in which the CACs switch from one brittle (TS position is a constant over a range of forces) state to another brittle state is not found in forced-rupture in other protein complexes. We explain this novel behavior by constructing the free energy profiles, F(Λ)s, as a function of a collective reaction coordinate (Λ), involving many key charged residues and a critical metal ion (Mg2+). The TS positions in F(Λ), which quantitatively agree with the parameters extracted using the Bell-Evans model, change abruptly at a critical force, demonstrating that it, rather than the molecular extension, is a good reaction coordinate. Our combined analyses using simulations performed in both the pulling modes (constant rf and F) reveal a new mechanism for the two loading regimes observed in the

  14. Effect of ambient humidity on the strength of the adhesion force of single yeast cell inside environmental-SEM

    International Nuclear Information System (INIS)

    Shen, Yajing; Nakajima, Masahiro; Ridzuan Ahmad, Mohd; Kojima, Seiji; Homma, Michio; Fukuda, Toshio

    2011-01-01

    A novel method for measuring an adhesion force of single yeast cell is proposed based on a nanorobotic manipulation system inside an environmental scanning electron microscope (ESEM). The effect of ambient humidity on a single yeast cell adhesion force was studied. Ambient humidity was controlled by adjusting the chamber pressure and temperature inside the ESEM. It has been demonstrated that a thicker water film was formed at a higher humidity condition. The adhesion force between an atomic force microscopy (AFM) cantilever and a tungsten probe which later on known as a substrate was evaluated at various humidity conditions. A micro-puller was fabricated from an AFM cantilever by use of focused ion beam (FIB) etching. The adhesion force of a single yeast cell (W303) to the substrate was measured using the micro-puller at the three humidity conditions: 100%, 70%, and 40%. The results showed that the adhesion force between the single yeast cell and the substrate is much smaller at higher humidity condition. The yeast cells were still alive after being observed and manipulated inside ESEM based on the result obtained from the re-culturing of the single yeast cell. The results from this work would help us to understand the ESEM system better and its potential benefit to the single cell analysis research. -- Research highlights: → A nanorobotic manipulation system was developed inside an ESEM. → A micro-puller was designed for single yeast cell adhesion force measurement. → Yeast cells were still alive after being observed and manipulated inside ESEM. → Yeast cell adhesion force to substrate is smaller at high humidity condition than at low humidity condition.

  15. Effect of ambient humidity on the strength of the adhesion force of single yeast cell inside environmental-SEM

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yajing, E-mail: shen@robo.mein.nagoya-u.ac.jp [Department of Micro-Nano Systems Engineering, Nagoya University, Nagoya 464-8603 (Japan); Nakajima, Masahiro [Department of Micro-Nano Systems Engineering, Nagoya University, Nagoya 464-8603 (Japan); Ridzuan Ahmad, Mohd [Department of Mechatronics and Robotics, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Skudai 81310 (Malaysia); Kojima, Seiji; Homma, Michio [Department of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602 (Japan); Fukuda, Toshio [Department of Micro-Nano Systems Engineering, Nagoya University, Nagoya 464-8603 (Japan)

    2011-07-15

    A novel method for measuring an adhesion force of single yeast cell is proposed based on a nanorobotic manipulation system inside an environmental scanning electron microscope (ESEM). The effect of ambient humidity on a single yeast cell adhesion force was studied. Ambient humidity was controlled by adjusting the chamber pressure and temperature inside the ESEM. It has been demonstrated that a thicker water film was formed at a higher humidity condition. The adhesion force between an atomic force microscopy (AFM) cantilever and a tungsten probe which later on known as a substrate was evaluated at various humidity conditions. A micro-puller was fabricated from an AFM cantilever by use of focused ion beam (FIB) etching. The adhesion force of a single yeast cell (W303) to the substrate was measured using the micro-puller at the three humidity conditions: 100%, 70%, and 40%. The results showed that the adhesion force between the single yeast cell and the substrate is much smaller at higher humidity condition. The yeast cells were still alive after being observed and manipulated inside ESEM based on the result obtained from the re-culturing of the single yeast cell. The results from this work would help us to understand the ESEM system better and its potential benefit to the single cell analysis research. -- Research highlights: {yields} A nanorobotic manipulation system was developed inside an ESEM. {yields} A micro-puller was designed for single yeast cell adhesion force measurement. {yields} Yeast cells were still alive after being observed and manipulated inside ESEM. {yields} Yeast cell adhesion force to substrate is smaller at high humidity condition than at low humidity condition.

  16. Interactions between Rotavirus and Suwannee River Organic Matter: Aggregation, Deposition, and Adhesion Force Measurement

    KAUST Repository

    Gutierrez, Leonardo

    2012-08-21

    Interactions between rotavirus and Suwannee River natural organic matter (NOM) were studied by time-resolved dynamic light scattering, quartz crystal microbalance, and atomic force microscopy. In NOM-containing NaCl solutions of up to 600 mM, rotavirus suspension remained stable for over 4 h. Atomic force microscopy (AFM) measurement for interaction force decay length at different ionic strengths showed that nonelectrostatic repulsive forces were mainly responsible for eliminating aggregation in NaCl solutions. Aggregation rates of rotavirus in solutions containing 20 mg C/L increased with divalent cation concentration until reaching a critical coagulation concentration of 30 mM CaCl2 or 70 mM MgCl2. Deposition kinetics of rotavirus on NOM-coated silica surface was studied using quartz crystal microbalance. Experimental attachment efficiencies for rotavirus adsorption to NOM-coated surface in MgCl2 solution were lower than in CaCl2 solution at a given divalent cation concentration. Stronger adhesion force was measured for virus-virus and virus-NOM interactions in CaCl2 solution compared to those in MgCl2 or NaCl solutions at the same ionic strength. This study suggested that divalent cation complexation with carboxylate groups in NOM and on virus surface was an important mechanism in the deposition and aggregation kinetics of rotavirus. © 2012 American Chemical Society.

  17. Spectral force analysis using atomic force microscopy reveals the importance of surface heterogeneity in bacterial and colloid adhesion to engineered surfaces.

    Science.gov (United States)

    Ma, Huilian; Winslow, Charles J; Logan, Bruce E

    2008-04-01

    Coatings developed to reduce biofouling of engineered surfaces do not always perform as expected based on their native properties. One reason is that a relatively small number of highly adhesive sites, or the heterogeneity of the coated surface, may control the overall response of the system to initial bacterial deposition. It is shown here using an approach we call spectral force analysis (SFA), based on force volume imaging of the surface with atomic force microscopy, that the behavior of surfaces and coatings can be better understood relative to bacterial adhesion. The application of vapor deposited TiO(2) metal oxide increased bacterial and colloid adhesion, but coating the surface with silica oxide reduced adhesion in a manner consistent with SFA based on analysis of the "stickiest" sites. Application of a TiO(2)-based paint to a surface produced a relatively non-fouling surface. Addition of a hydrophilic layer coating to this surface should have decreased fouling. However, it was observed that this coating actually increased fouling. Using SFA it was shown that the reason for the increased adhesion of bacteria and particles to the hydrophilic layer was that the surface produced by this coating was highly heterogeneous, resulting in a small number of sites that created a stickier surface. These results show that while it is important to manufacture surfaces with coatings that are relatively non-adhesive to bacteria, it is also essential that these coatings have a highly uniform surface chemistry.

  18. Atomic force microscope adhesion measurements and atomistic molecular dynamics simulations at different humidities

    International Nuclear Information System (INIS)

    Seppä, Jeremias; Sairanen, Hannu; Korpelainen, Virpi; Husu, Hannu; Heinonen, Martti; Lassila, Antti; Reischl, Bernhard; Raiteri, Paolo; Rohl, Andrew L; Nordlund, Kai

    2017-01-01

    Due to their operation principle atomic force microscopes (AFMs) are sensitive to all factors affecting the detected force between the probe and the sample. Relative humidity is an important and often neglected—both in experiments and simulations—factor in the interaction force between AFM probe and sample in air. This paper describes the humidity control system designed and built for the interferometrically traceable metrology AFM (IT-MAFM) at VTT MIKES. The humidity control is based on circulating the air of the AFM enclosure via dryer and humidifier paths with adjustable flow and mixing ratio of dry and humid air. The design humidity range of the system is 20–60 %rh. Force–distance adhesion studies at humidity levels between 25 %rh and 53 %rh are presented and compared to an atomistic molecular dynamics (MD) simulation. The uncertainty level of the thermal noise method implementation used for force constant calibration of the AFM cantilevers is 10 %, being the dominant component of the interaction force measurement uncertainty. Comparing the simulation and the experiment, the primary uncertainties are related to the nominally 7 nm radius and shape of measurement probe apex, possible wear and contamination, and the atomistic simulation technique details. The interaction forces are of the same order of magnitude in simulation and measurement (5 nN). An elongation of a few nanometres of the water meniscus between probe tip and sample, before its rupture, is seen in simulation upon retraction of the tip in higher humidity. This behaviour is also supported by the presented experimental measurement data but the data is insufficient to conclusively verify the quantitative meniscus elongation. (paper)

  19. Elastic model of the traction behavior of two traction lubricants

    Science.gov (United States)

    Loewenthal, S. H.; Rohn, D. A.

    1984-01-01

    In the analysis of rolling-sliding concentrated contacts, such as gears, bearings and traction drives, the traction characteristics of the lubricant are of prime importance. The elastic shear modulus and limiting shear stress properties of the lubricant dictate the traction/slip characteristics and power loss associated with an EHD contact undergoing slip and/or spin. These properties can be deducted directly from the initial slope m and maximum traction coefficient micron of an experimental traction curve. In this investigation, correlation equations are presented to predict m and micron for two modern traction fluids based on the regression analysis of 334 separate traction disk machine experiments. The effects of contact pressure, temperature, surface velocity, ellipticity ratio are examined. Problems in deducing lubricant shear moduli from disk machine tests are discussed. Previously announced in STAR as N83-20116

  20. Single cell adhesion force measurement for cell viability identification using an AFM cantilever-based micro putter

    Science.gov (United States)

    Shen, Yajing; Nakajima, Masahiro; Kojima, Seiji; Homma, Michio; Kojima, Masaru; Fukuda, Toshio

    2011-11-01

    Fast and sensitive cell viability identification is a key point for single cell analysis. To address this issue, this paper reports a novel single cell viability identification method based on the measurement of single cell shear adhesion force using an atomic force microscopy (AFM) cantilever-based micro putter. Viable and nonviable yeast cells are prepared and put onto three kinds of substrate surfaces, i.e. tungsten probe, gold and ITO substrate surfaces. A micro putter is fabricated from the AFM cantilever by focused ion beam etching technique. The spring constant of the micro putter is calibrated using the nanomanipulation approach. The shear adhesion force between the single viable or nonviable cell and each substrate is measured using the micro putter based on the nanorobotic manipulation system inside an environmental scanning electron microscope. The adhesion force is calculated based on the deflection of the micro putter beam. The results show that the adhesion force of the viable cell to the substrate is much larger than that of the nonviable cell. This identification method is label free, fast, sensitive and can give quantitative results at the single cell level.

  1. Influence of the Molecular Adhesion Force on the Indentation Depth of a Particle into the Wafer Surface in the CMP Process

    Directory of Open Access Journals (Sweden)

    Zhou Jianhua

    2014-01-01

    Full Text Available By theoretical calculation, the external force on the particle conveyed by pad asperities and the molecular adhesion force between particle and wafer are compared and analyzed quantitatively. It is confirmed that the molecular adhesion force between particle and wafer has a great influence on the chemical mechanical polishing (CMP material removal process. Considering the molecular adhesion force between particle and wafer, a more precise model for the indentation of a particle into the wafer surface is developed in this paper, and the new model is compared with the former model which neglected the molecular adhesion force. Through theoretical analyses, an approach and corresponding critical values are applied to estimate whether the molecular adhesion force in CMP can be neglected. These methods can improve the precision of the material removal model of CMP.

  2. Targeted traction of impacted teeth with C-tube miniplates.

    Science.gov (United States)

    Chung, Kyu-Rhim; Kim, Yong; Ahn, Hyo-Won; Lee, Dongjoo; Yang, Dong-Min; Kim, Seong-Hun; Nelson, Gerald

    2014-09-01

    Orthodontic traction of impacted teeth has typically been performed using full fixed appliance as anchorage against the traction force. This conventional approach can be difficult to apply in the mixed dentition if the partial fixed appliance offers an insufficient anchor unit. In addition, full fixed appliance can induce unwanted movement of adjacent teeth. This clinical report presents 3 cases where impacted teeth were recovered in the mixed or transitional dentition with skeletal anchorage on the opposite arch without full fixed appliance. Instead, intermaxillary traction was used to bring the impacted teeth into position. With this approach, side effects on teeth and periodontal tissues adjacent to the impaction were minimized.

  3. Energy and wear optimisation of train longitudinal dynamics and of traction and braking systems

    Science.gov (United States)

    Conti, R.; Galardi, E.; Meli, E.; Nocciolini, D.; Pugi, L.; Rindi, A.

    2015-05-01

    Traction and braking systems deeply affect longitudinal train dynamics, especially when an extensive blending phase among different pneumatic, electric and magnetic devices is required. The energy and wear optimisation of longitudinal vehicle dynamics has a crucial economic impact and involves several engineering problems such as wear of braking friction components, energy efficiency, thermal load on components, level of safety under degraded or adhesion conditions (often constrained by the current regulation in force on signalling or other safety-related subsystem). In fact, the application of energy storage systems can lead to an efficiency improvement of at least 10% while, as regards the wear reduction, the improvement due to distributed traction systems and to optimised traction devices can be quantified in about 50%. In this work, an innovative integrated procedure is proposed by the authors to optimise longitudinal train dynamics and traction and braking manoeuvres in terms of both energy and wear. The new approach has been applied to existing test cases and validated with experimental data provided by Breda and, for some components and their homologation process, the results of experimental activities derive from cooperation performed with relevant industrial partners such as Trenitalia and Italcertifer. In particular, simulation results are referred to the simulation tests performed on a high-speed train (Ansaldo Breda Emu V250) and on a tram (Ansaldo Breda Sirio Tram). The proposed approach is based on a modular simulation platform in which the sub-models corresponding to different subsystems can be easily customised, depending on the considered application, on the availability of technical data and on the homologation process of different components.

  4. Disc-shaped LIM for levitation and traction force control powered by the source using the component synchronous with the motor speed

    Directory of Open Access Journals (Sweden)

    Morizane Toshimitsu

    2015-12-01

    Full Text Available It has been proposed that a novel maglev transport system uses both of the attractive force and thrust force of the Linear Induction Motor (LIM. In our proposal, these two forces will be controlled by two different frequency components. One of the frequency components is synchronous with the motor speed (fm. Another frequency component is drive frequency (fd. Our proposed system enables the independent and simultaneous control of the attractive and thrust force of LIM. Each value of the attractive and the thrust force generated by fm and fd must be identified in order to design that LIM control system. For these purpose, a disc-shaped LIM has been developed as an experimental equipment. The force profiles, especially around zero slip, have been analyzed under experimental conditions.

  5. Unusual Complication of Suprapubic Cystostomy in a Male Patient with Tetraplegia: Traction on Foley Catheter Leading to Extrusion of Foley Balloon from Urinary Bladder and Suprapubic Urinary Fistula – Importance of Securely Anchoring Suprapubic Catheter with Adhesive Tape or BioDerm Tube Holder

    Directory of Open Access Journals (Sweden)

    Subramanian Vaidyanathan

    2007-01-01

    Full Text Available Suprapubic cystostomy is recommended to patients with neuropathic bladder to prevent complications of long-term urethral catheter drainage. We present a 50-year-old male patient with tetraplegia who had long-term urethral catheter drainage. Following flexible cystoscopy, he developed a urine leak from the right side of the scrotum. Suprapubic cystostomy was performed. After suprapubic cystostomy, the urinary fistula healed completely. A follow-up cystourethrogram confirmed an intact urethra with no leak of contrast. Six weeks later, this patient presented with a hole below the suprapubic cystostomy through which a small amount of urine was leaking. A keyhole dressing had been applied around the suprapubic catheter and the catheter was hanging loosely, thus permitting traction on the catheter, especially when the urine bag was full. Computerised tomography of the pelvis showed extrusion of the Foley balloon from the urinary bladder, but the tip of the catheter was still located within the bladder. The extruded catheter was removed and a Foley catheter was inserted, ensuring that the balloon was inflated within the urinary bladder. The suprapubic catheter was secured firmly to the anterior abdominal wall with a BioDerm Tube Holder, thus preventing any traction on the catheter or Foley balloon. The urine leak through the hole below the suprapubic cystostomy stopped and the sinus healed. This case illustrates the need to anchor the suprapubic catheter securely to the anterior abdominal wall with adhesive tape or BioDerm Tube Holder to prevent traction and consequent displacement of the catheter or Foley balloon.

  6. Influence of the adhesion force crystal/heat exchanger surface on fouling mitigation

    International Nuclear Information System (INIS)

    Forster, M.; Augustin, W.; Bohnet, M.

    1999-01-01

    The accumulation of unwanted crystalline deposits (fouling) reduces the efficiency of heat exchangers considerably. In order to decrease the cost of fouling two strategies have been developed. The first fouling mitigation strategy is based on the modification of energy-and-geometry-related characteristics of the heat transfer surface to realize an increased duration of the induction period. By means of a drop-shape-analysis measurement device the interaction at the interface crystal/heat transfer surface is determined. The deployment of the fracture energy model and the interfacial defect model relates wetting characteristics to the adhesion phenomenon. Hence, a first estimation of the optimal choice of surface material is realized. Furthermore, the influence of surface topography on interfacial interactions has been analyzed. The second fouling mitigation strategy is based on the adjustment of the hydrodynamic flow conditions using a pulsation technique. Here, single strokes of higher velocity are superimposed on the stationary flow. These strokes shift the equilibrium of forces to an improved removal process. Fouling experiments have proved that pulsation is a powerful tool to mitigate the built-up of fouling layers on heat transfer surfaces. (author)

  7. Advanced Integrated Traction System

    Energy Technology Data Exchange (ETDEWEB)

    Greg Smith; Charles Gough

    2011-08-31

    The United States Department of Energy elaborates the compelling need for a commercialized competitively priced electric traction drive system to proliferate the acceptance of HEVs, PHEVs, and FCVs in the market. The desired end result is a technically and commercially verified integrated ETS (Electric Traction System) product design that can be manufactured and distributed through a broad network of competitive suppliers to all auto manufacturers. The objectives of this FCVT program are to develop advanced technologies for an integrated ETS capable of 55kW peak power for 18 seconds and 30kW of continuous power. Additionally, to accommodate a variety of automotive platforms the ETS design should be scalable to 120kW peak power for 18 seconds and 65kW of continuous power. The ETS (exclusive of the DC/DC Converter) is to cost no more than $660 (55kW at $12/kW) to produce in quantities of 100,000 units per year, should have a total weight less than 46kg, and have a volume less than 16 liters. The cost target for the optional Bi-Directional DC/DC Converter is $375. The goal is to achieve these targets with the use of engine coolant at a nominal temperature of 105C. The system efficiency should exceed 90% at 20% of rated torque over 10% to 100% of maximum speed. The nominal operating system voltage is to be 325V, with consideration for higher voltages. This project investigated a wide range of technologies, including ETS topologies, components, and interconnects. Each technology and its validity for automotive use were verified and then these technologies were integrated into a high temperature ETS design that would support a wide variety of applications (fuel cell, hybrids, electrics, and plug-ins). This ETS met all the DOE 2010 objectives of cost, weight, volume and efficiency, and the specific power and power density 2015 objectives. Additionally a bi-directional converter was developed that provides charging and electric power take-off which is the first step

  8. Adhesion strength of a living cell to various substrates measured using a cup-attached atomic force microscopy chip

    Science.gov (United States)

    Kim, Hyonchol; Ishibashi, Kenta; Matsuo, Kosuke; Kira, Atsushi; Onomura, Yui; Okada, Tomoko; Nakamura, Chikashi

    2018-03-01

    Cell adhesion strengths to various substrates were quantitatively measured using atomic force microscopy (AFM). A cup-shaped metal hemisphere was attached to the apex of the AFM cantilever, the “cup-chip” approached a cell (FP10SC2) to pick it up, the captured cell approached any one of six different substrates [gold (Au), nickel (Ni), bovine serum albumin (BSA), an amino group (NH2), poly(tetrafluoroethylene) (PTFE), and structured PTFE (sPTFE)], and the cell adhesion strength at the initial contact period was evaluated by detaching the cell from the substrate. The results obtained showed that the force needed to detach the cell from the NH2 substrate was more than 3-fold larger than that of metal substrates (Au and Ni), more than 15-fold larger than that of biochemically treated substrates (BSA), and more than 20-fold larger than that of hydrophobic substrates (PTFE and sPTFE). Using differences in adhesion strengths, a cell on a sPTFE substrate was picked up using a BSA-coated cup-chip, placed on a NH2 substrate, repeating this cell manipulation five times, and line patterning of cells was achieved. These results indicate that measurements of cell adhesion strength are fundamental to fabricate desired cell networks and the cup-chip is a useful tool for achieving easy cell manipulation.

  9. Manipulation of polystyrene nanoparticles on a silicon wafer in the peak force tapping mode in water: pH-dependent friction and adhesion force

    Energy Technology Data Exchange (ETDEWEB)

    Schiwek, Simon; Stark, Robert W., E-mail: stark@csi.tu-darmstadt.de, E-mail: dietz@csi.tu-darmstadt.de; Dietz, Christian, E-mail: stark@csi.tu-darmstadt.de, E-mail: dietz@csi.tu-darmstadt.de [Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Heim, Lars-Oliver [Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany)

    2015-03-14

    The friction force between nanoparticles and a silicon wafer is a crucial parameter for cleaning processes in the semiconductor industry. However, little is known about the pH-dependency of the friction forces and the shear strength at the interface. Here, we push polystyrene nanoparticles, 100 nm in diameter, with the tip of an atomic force microscope and measure the pH-dependency of the friction, adhesion, and normal forces on a silicon substrate covered with a native silicon dioxide layer. The peak force tapping mode was applied to control the vertical force on these particles. We successively increased the applied load until the particles started to move. The main advantage of this technique over single manipulation processes is the achievement of a large number of manipulation events in short time and in a straightforward manner. Geometrical considerations of the interaction forces at the tip-particle interface allowed us to calculate the friction force and shear strength from the applied normal force depending on the pH of an aqueous solution. The results clearly demonstrated that particle removal should be performed with a basic solution at pH 9 because of the low interaction forces between particle and substrate.

  10. Atomic force microscopic corroboration of bond ageing for adhesion of Streptococcus thermophilus to solid substrata

    NARCIS (Netherlands)

    Vadillo-Rodriguez, V.; Busscher, H.J.; Norde, W.; Vries, de J.

    2004-01-01

    Initial bacterial adhesion is considered to be reversible, but over time the adhesive bond between a bacterium and a substratum surface may strengthen, turning the process into an irreversible state. Microbial desorption has been studied in situ in controlled flow devices as a function of the

  11. A fast and quantitative evaluation of the Aspergillus fumigatus biofilm adhesion properties by means of digital pulsed force mode

    International Nuclear Information System (INIS)

    Maiorana, Alessandro; Papi, Massimiliano; Bugli, Francesca; Torelli, Riccardo; Maulucci, Giuseppe; Cacaci, Margherita; Posteraro, Brunella; Sanguinetti, Maurizio; De Spirito, Marco

    2013-01-01

    The opportunistic pathogenic mould Aspergillus fumigatus (A. fumigatus) is an increasing cause of morbidity and mortality in immunocompromised and in part immunocompetent patients. A. fumigatus can grow in multicellular communities by the formation of a hyphal network embedded in an extracellular matrix (ECM) meanly composed by polysaccharides, melanin, proteins. Because adhesion properties is one primary factor affecting the balance between growth, detachment and biofilm formation, its quantification is essential in understanding, predicting, and modelling biofilm development. Atomic force microscopy (AFM) imaging and force spectroscopy have recently opened a range of novel applications in microbiology including the imaging and manipulation of membrane proteins at the subnanometer level, the observation of the surface of living cells at high resolution, the mapping of local properties such as surface charges, the measurement of elastic properties of cell-surface constituents and the probing of cellular interactions using functionalized probes. Nevertheless, the principal disadvantage of this approach is the relatively slow acquisition rate that makes AFM is not able to detect fast dynamics. In this study we demonstrated that digital pulsed force mode (DPFM) atomic force microscopy can be used to obtain high-resolution topographical images and to quantify the adhesion properties of the A. fumigatus biofilm with an high acquisition rate. Here we show by means of DPFM-AFM that Alginate Lyase (AlgL), an enzyme known to reduce negatively charged alginate levels in microbial biofilm, is able to reduce the biofilm adhesion forces forming several nano-fractures in the ECM. These results suggest that the AlgL could used to enhance the antifungal drugs transit through the ECM.

  12. A fast and quantitative evaluation of the Aspergillus fumigatus biofilm adhesion properties by means of digital pulsed force mode

    Energy Technology Data Exchange (ETDEWEB)

    Maiorana, Alessandro [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Papi, Massimiliano, E-mail: m.papi@rm.unicatt.it [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Bugli, Francesca; Torelli, Riccardo [Istituto di Microbiologia, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Maulucci, Giuseppe [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Cacaci, Margherita; Posteraro, Brunella; Sanguinetti, Maurizio [Istituto di Microbiologia, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); De Spirito, Marco [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy)

    2013-08-15

    The opportunistic pathogenic mould Aspergillus fumigatus (A. fumigatus) is an increasing cause of morbidity and mortality in immunocompromised and in part immunocompetent patients. A. fumigatus can grow in multicellular communities by the formation of a hyphal network embedded in an extracellular matrix (ECM) meanly composed by polysaccharides, melanin, proteins. Because adhesion properties is one primary factor affecting the balance between growth, detachment and biofilm formation, its quantification is essential in understanding, predicting, and modelling biofilm development. Atomic force microscopy (AFM) imaging and force spectroscopy have recently opened a range of novel applications in microbiology including the imaging and manipulation of membrane proteins at the subnanometer level, the observation of the surface of living cells at high resolution, the mapping of local properties such as surface charges, the measurement of elastic properties of cell-surface constituents and the probing of cellular interactions using functionalized probes. Nevertheless, the principal disadvantage of this approach is the relatively slow acquisition rate that makes AFM is not able to detect fast dynamics. In this study we demonstrated that digital pulsed force mode (DPFM) atomic force microscopy can be used to obtain high-resolution topographical images and to quantify the adhesion properties of the A. fumigatus biofilm with an high acquisition rate. Here we show by means of DPFM-AFM that Alginate Lyase (AlgL), an enzyme known to reduce negatively charged alginate levels in microbial biofilm, is able to reduce the biofilm adhesion forces forming several nano-fractures in the ECM. These results suggest that the AlgL could used to enhance the antifungal drugs transit through the ECM.

  13. A Facile All-Solution-Processed Surface with High Water Contact Angle and High Water Adhesive Force.

    Science.gov (United States)

    Chen, Mei; Hu, Wei; Liang, Xiao; Zou, Cheng; Li, Fasheng; Zhang, Lanying; Chen, Feiwu; Yang, Huai

    2017-07-12

    A series of sticky superhydrophobicity surfaces with high water contact angle and high water adhesive force is facilely prepared via an all-solution-processed method based on polymerization-induced phase separation between liquid crystals (LCs) and epoxy resin, which produces layers of epoxy microspheres (EMSs) with nanofolds on the surface of a substrate. The morphologies and size distributions of EMSs are confirmed by scanning electron microscopy. Results reveal that the obtained EMS coated-surface exhibits high apparent contact angle of 152.0° and high water adhesive force up to 117.6 μN. By varying the composition of the sample or preparing conditions, the sizes of the produced EMSs can be artificially regulated and, thus, control the wetting properties and water adhesive behaviors. Also, the sticky superhydrophobic surface exhibits excellent chemical stability, as well as long-term durability. Water droplet transportation experiments further prove that the as-made surface can be effectively used as a mechanical hand for water transportation applications. Based on this, it is believed that the simple method proposed in this paper will pave a new way for producing a sticky superhydrophobic surface and obtain a wide range of use.

  14. Interactions between Rotavirus and Suwannee River Organic Matter: Aggregation, Deposition, and Adhesion Force Measurement

    KAUST Repository

    Gutierrez, Leonardo; Nguyen, Thanh H.

    2012-01-01

    M, rotavirus suspension remained stable for over 4 h. Atomic force microscopy (AFM) measurement for interaction force decay length at different ionic strengths showed that nonelectrostatic repulsive forces were mainly responsible for eliminating aggregation

  15. Footwear traction and lower extremity noncontact injury.

    Science.gov (United States)

    Wannop, John W; Luo, Geng; Stefanyshyn, Darren J

    2013-11-01

    Football is the most popular high school sport; however, it has the highest rate of injury. Speculation has been prevalent that foot fixation due to high footwear traction contributes to injury risk. Therefore, the purpose of the study was to determine whether a relationship exists between the athlete's specific footwear traction (measured with their own shoes on the field of play) and lower extremity noncontact injury in high school football. For 3 yr, 555 high school football athletes had their footwear traction measured on the actual field of play at the start of the season, and any injury the athletes suffered during a game was recorded. Lower extremity noncontact injury rates, grouped based on the athlete's specific footwear traction (both translational and rotational), were compared. For translational traction, injury rate reached a peak of 23.3 injuries/1000 game exposures within the midrange of translational traction, before decreasing to 5.0 injuries/1000 game exposures in the high range of traction. For rotational traction, there was a steady increase in injury rate as footwear traction increased, starting at 4.2 injuries/1000 game exposures at low traction and reaching 19.2 injuries/1000 game exposures at high traction. A relationship exists between footwear traction and noncontact lower extremity injury, with increases in rotational traction leading to a greater injury rate and increases in translational traction leading to a decrease in injury. It is recommended that athletes consider selecting footwear with the lowest rotational traction values for which no detriment in performance results.

  16. Binding affinity and adhesion force of organophosphate hydrolase enzyme with soil particles related to the isoelectric point of the enzyme.

    Science.gov (United States)

    Islam, Shah Md Asraful; Yeasmin, Shabina; Islam, Md Saiful; Islam, Md Shariful

    2017-07-01

    The binding affinity of organophosphate hydrolase enzyme (OphB) with soil particles in relation to the isoelectric point (pI) was studied. Immobilization of OphB with soil particles was observed by confocal microscopy, Fourier transform infrared spectroscopy (FT-IR), and Atomic force microscopy (AFM). The calculated pI of OphB enzyme was increased from 8.69 to 8.89, 9.04 and 9.16 by the single, double and triple mutant of OphB enzyme, respectively through the replacement of negatively charged aspartate with positively charged histidine. Practically, the binding affinity was increased to 5.30%, 11.50%, and 16.80% for single, double and triple mutants, respectively. In contrast, enzyme activity of OphB did not change by the mutation of the enzyme. On the other hand, adhesion forces were gradually increased for wild type OphB enzyme (90 pN) to 96, 100 and 104 pN for single, double and triple mutants of OphB enzyme, respectively. There was an increasing trend of binding affinity and adhesion force by the increase of isoelectric point (pI) of OphB enzyme. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Effects of swelling forces on the durability of wood adhesive bonds

    Science.gov (United States)

    Blake M. Hofferber; Edward Kolodka; Rishawn Brandon; Robert J. Moon; Charles R. Frihart

    2006-01-01

    The purpose of this study was to investigate the role of wood swelling on performance of wood-adhesive bonds (resorcinol formaldehyde, epoxy, emulsion polymerisocyanate), for untreated and acetylated wood. Effects of these treatments on measured strain anisotropy and swelling stress were measured and then related to compressive shear strength and percentage wood...

  18. Computation of Slip analysis to detect adhesion for protection of rail vehicle and derailment

    Directory of Open Access Journals (Sweden)

    Zulfiqar Ali Soomro

    2015-07-01

    Full Text Available Adhesion level for the proper running of rail wheelset on track is crucial problem in detecting slippage to avoid accidents. The slippage of rail wheels has been observed applying forward and lateral motions to slip velocity and torsion motion. The longitudinal and lateral forces behavior is watched with respect to traction force to note correlation based on angle of attack. The deriving torque relation with tractive torque is watched to check slippage. Coulomb’s law is applied in terms of tangential forces to normal forces owing to creep co-efficient and friction to know adhesion. Nadal’s limiting ratio is applied to escape from wheel climb and derailment from track depending upon wheel profile and flange on straight path and curves.

  19. Variation of adhesive force at the interface of Pd and SrTiO3 as a consequence of residual stresses

    International Nuclear Information System (INIS)

    Nazarpour, Soroush; Cirera, Albert

    2011-01-01

    Initially, Pd thin films were deposited over a hard substrate using electron beam physical vapour deposition. The growth and the surface roughness of the films were analysed and their effects upon the conventional indentation test were discussed. Afterwards, an experimental method is described which can measure the critical fracture force in thin films using oscillating indentation. Initially, repetitive contacts at a single point with the purpose of identifying the fracture time provide the fracture force versus fracture time plot. Non-linear curve fitting of the data reveals the theoretical fracture force by a single indentation, which is called the critical fracture force. Arguments are put forward to show the relation between piling up height and applied force. Discrepancies were observed in the plot of the ratio between total indentation depth and piling up height versus applied force when higher loads than a critical fracture force were applied. Discrepancies appear as a result of indenting the substrate. A nanoscratch test facilitated the possibility of measuring adhesion strength and adhesion energy of the films considering the measured critical fracture force as the maximum applied force. The relation between residual compressive stresses, adhesion strength, plastic deformation and piling up area was discussed using dislocation theories. Indentation with high applied loads leaves behind large plastic deformation and reduces the accuracy and reliability of the test results. Hence, lower loads (in the order of nanonewtons) were applied using atomic force microscopy in the friction mode. A pulling off force was mapped in each thickness of Pd films. The results confirm that the area around a hillock exhibits a higher pulling off force due to the local stress relaxation as a consequence of hillock formation. By repeating the mapping process over different areas with various applying forces, the plot of the pulling off force versus applied load was drawn

  20. Underwater adhesion of abalone: The role of van der Waals and capillary forces

    Energy Technology Data Exchange (ETDEWEB)

    Lin, A.Y.M., E-mail: albertlin22@yahoo.com [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Brunner, R. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States)] [Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093 (United States); Chen, P.Y. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Talke, F.E. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States)] [Center for Magnetic Recording Research, University of California, San Diego, La Jolla, CA 92093 (United States); Meyers, M.A. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States)] [Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093 (United States)] [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States)

    2009-08-15

    The observation of the pedal foot of the red abalone Haliotis rufescens reveals the presence of micrometer-scaled setae terminating in nanometer-sized cylindrical fibrils, with some resemblance to those found on the gecko foot. Atomic force microscopy (AFM) pull-off force measurements on a single seta are compared with theoretical estimates for van der Waals attraction obtained through the Johnson-Kendall-Roberts (JKR) equation, approximately 600 nN, and show agreement. The use of the JKR equation is justified through an analysis of the shape of the fibril extremities (parabolic) as well as their diameter ({approx}200 nm). Measurements under varying humidity conditions indicate that additional capillary interactions play a role, since the pull-off force increases with humidity. It is proposed that both van der Waals and capillary forces play a role in the attachment mechanism of H. rufescens, effectively enabling suction to reach its theoretical limit. Bulk pull-off force measurements on entire live animals yield an average detachment stress of 115 kPa, consistent with theoretical estimates. The setae and nanoscale fibril terminations enable compliance to surfaces with a variety of roughnesses, effectively sealing the interface, in addition to providing capillary and van der Waals forces.

  1. Underwater adhesion of abalone: The role of van der Waals and capillary forces

    International Nuclear Information System (INIS)

    Lin, A.Y.M.; Brunner, R.; Chen, P.Y.; Talke, F.E.; Meyers, M.A.

    2009-01-01

    The observation of the pedal foot of the red abalone Haliotis rufescens reveals the presence of micrometer-scaled setae terminating in nanometer-sized cylindrical fibrils, with some resemblance to those found on the gecko foot. Atomic force microscopy (AFM) pull-off force measurements on a single seta are compared with theoretical estimates for van der Waals attraction obtained through the Johnson-Kendall-Roberts (JKR) equation, approximately 600 nN, and show agreement. The use of the JKR equation is justified through an analysis of the shape of the fibril extremities (parabolic) as well as their diameter (∼200 nm). Measurements under varying humidity conditions indicate that additional capillary interactions play a role, since the pull-off force increases with humidity. It is proposed that both van der Waals and capillary forces play a role in the attachment mechanism of H. rufescens, effectively enabling suction to reach its theoretical limit. Bulk pull-off force measurements on entire live animals yield an average detachment stress of 115 kPa, consistent with theoretical estimates. The setae and nanoscale fibril terminations enable compliance to surfaces with a variety of roughnesses, effectively sealing the interface, in addition to providing capillary and van der Waals forces.

  2. The role of the cytoskeleton in cellular force generation in 2D and 3D environments

    International Nuclear Information System (INIS)

    Kraning-Rush, Casey M; Carey, Shawn P; Califano, Joseph P; Smith, Brooke N; Reinhart-King, Cynthia A

    2011-01-01

    To adhere and migrate, cells generate forces through the cytoskeleton that are transmitted to the surrounding matrix. While cellular force generation has been studied on 2D substrates, less is known about cytoskeletal-mediated traction forces of cells embedded in more in vivo-like 3D matrices. Recent studies have revealed important differences between the cytoskeletal structure, adhesion, and migration of cells in 2D and 3D. Because the cytoskeleton mediates force, we sought to directly compare the role of the cytoskeleton in modulating cell force in 2D and 3D. MDA-MB-231 cells were treated with agents that perturbed actin, microtubules, or myosin, and analyzed for changes in cytoskeletal organization and force generation in both 2D and 3D. To quantify traction stresses in 2D, traction force microscopy was used; in 3D, force was assessed based on single cell-mediated collagen fibril reorganization imaged using confocal reflectance microscopy. Interestingly, even though previous studies have observed differences in cell behaviors like migration in 2D and 3D, our data indicate that forces generated on 2D substrates correlate with forces within 3D matrices. Disruption of actin, myosin or microtubules in either 2D or 3D microenvironments disrupts cell-generated force. These data suggest that despite differences in cytoskeletal organization in 2D and 3D, actin, microtubules and myosin contribute to contractility and matrix reorganization similarly in both microenvironments

  3. Counter traction makes endoscopic submucosal dissection easier.

    Science.gov (United States)

    Oyama, Tsuneo

    2012-11-01

    Poor counter traction and poor field of vision make endoscopic submucosal dissection (ESD) difficult. Good counter traction allows dissections to be performed more quickly and safely. Position change, which utilizes gravity, is the simplest method to create a clear field of vision. It is useful especially for esophageal and colon ESD. The second easiest method is clip with line method. Counter traction made by clip with line accomplishes the creation of a clear field of vision and suitable counter traction thereby making ESD more efficient and safe. The author published this method in 2002. The name ESD was not established in those days; the name cutting endoscopic mucosal resection (EMR) or EMR with hook knife was used. The other traction methods such as external grasping forceps, internal traction, double channel scope, and double scopes method are introduced in this paper. A good strategy for creating counter traction makes ESD easier.

  4. The effects of adhesive forces on the collision behavior of polyolefin particles

    Czech Academy of Sciences Publication Activity Database

    Ledvinková, Blanka; Kosek, J.

    2013-01-01

    Roč. 243, July (2013), s. 27-39 ISSN 0032-5910 R&D Projects: GA ČR GA103/09/2066 Institutional support: RVO:67985874 Keywords : adhersive forces * agglomeration * chain entanglement * discrete element method * gas polymerization Subject RIV: BK - Fluid Dynamics Impact factor: 2.269, year: 2013 http://www.sciencedirect.com/science/article/pii/S0032591013002362

  5. Climbing ability of teneral and sclerotized adult bed bugs and assessment of adhesive properties of the exoskeletal fluid using atomic force microscopy.

    Directory of Open Access Journals (Sweden)

    Kevin R Hinson

    Full Text Available We observed that teneral adults (72 h, and sclerotized group 2 (S2 bed bugs (n = 30, height climbed = 2.64 cm at >72 h post molt. When heights from all climbing events were summed, teneral bed bugs (650.8 cm climbed differed significantly (P< 0.01 from recently sclerotized (82 cm climbed and sclerotized (group 1 = 104.6 cm climbed, group 2 = 107.8 cm climbed bed bugs. These findings suggested that the external surface of teneral bed bug exoskeletons possess an adhesive property. Using atomic force microscopy (AFM, we found that adhesion force of an exoskeletal (presumably molting fluid decreased almost five-fold from 88 to 17 nN within an hour of molting. Our findings may have implications for laboratory safety and the effectiveness of bed bug traps, barriers, and biomimetic-based adhesives.

  6. Plica neuropathica causing traction alopecia

    Directory of Open Access Journals (Sweden)

    K Pavithran

    1990-01-01

    Full Text Available A middle aged woman developed matting of the hairs of the scalp following use of a home made shampoo that contained leaves of Hibiscus rosasiensis. The entangled and matted hair mass in the occipital region pulled hairs of the vertex region of the scalp, resulting in a patch of traction alopecia. Release of tension on the hairs by cutting them with scissors prevented further extension of alopecia.

  7. The impact of the neurodevelopmental traction technique on activation of lateral abdominal muscles in children aged 11-13 years.

    Science.gov (United States)

    Gogola, Anna; Gnat, Rafał; Dziub, Dorota; Gwóźdź, Michalina; Zaborowska, Małgorzata

    2016-06-27

    The aim of the study was to evaluate the activation of lateral abdominal muscles (LAM) in response to neurodevelopmental traction technique as assessed by ultrasounds as well as to compare the effects of different traction forces. An experiment with repeated measurements of the dependent variables was conducted. Thirty-seven children (22 girls) participated. Measurements of LAM thickness (indicating LAM activation) were performed bilaterally during traction of 5% body weight: 1) in neutral position, 2) in 20° posterior trunk inclination; during traction of 15% body weight: 3) in neutral position, 4) in 20° posterior trunk inclination. The ultrasound technology was employed. When applying the lighter traction the superficial LAM (external and internal oblique muscles) showed significant changes. The mean thickness of both muscles during traction increased (both p  0.05). Stronger traction elicited smaller changes. External and internal oblique muscles showed significant increases (p stronger traction (p Stronger traction induces smaller LAM thickness changes than lighter traction.

  8. Counter Traction Makes Endoscopic Submucosal Dissection Easier

    OpenAIRE

    Oyama, Tsuneo

    2012-01-01

    Poor counter traction and poor field of vision make endoscopic submucosal dissection (ESD) difficult. Good counter traction allows dissections to be performed more quickly and safely. Position change, which utilizes gravity, is the simplest method to create a clear field of vision. It is useful especially for esophageal and colon ESD. The second easiest method is clip with line method. Counter traction made by clip with line accomplishes the creation of a clear field of vision and suitable co...

  9. Traction Control System for Motorcycles

    Directory of Open Access Journals (Sweden)

    Cardinale Pascal

    2009-01-01

    Full Text Available Traction control is a widely used control system to increase stability and safety of four wheel vehicles. Automatic stability control is used in the BMW K1200R motorcycle and in motoGP competition, but not in other motorcycles. This paper presents an algorithm and a low-cost real-time hardware implementation for motorcycles. A prototype has been developed, applied on a commercial motorcycle, and tested in a real track. The control system that can be tuned by the driver during the race has been appreciated by the test driver.

  10. Tire-road friction estimation and traction control strategy for motorized electric vehicle

    Science.gov (United States)

    Jin, Li-Qiang; Yue, Weiqiang

    2017-01-01

    In this paper, an optimal longitudinal slip ratio system for real-time identification of electric vehicle (EV) with motored wheels is proposed based on the adhesion between tire and road surface. First and foremost, the optimal longitudinal slip rate torque control can be identified in real time by calculating the derivative and slip rate of the adhesion coefficient. Secondly, the vehicle speed estimation method is also brought. Thirdly, an ideal vehicle simulation model is proposed to verify the algorithm with simulation, and we find that the slip ratio corresponds to the detection of the adhesion limit in real time. Finally, the proposed strategy is applied to traction control system (TCS). The results showed that the method can effectively identify the state of wheel and calculate the optimal slip ratio without wheel speed sensor; in the meantime, it can improve the accelerated stability of electric vehicle with traction control system (TCS). PMID:28662053

  11. 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.

  12. Physical Basis for Interfacial Traction-Separation Models

    International Nuclear Information System (INIS)

    Neville R. Moody

    2002-01-01

    Many weapon components contain interfaces between dissimilar materials where cracks can initiate and cause failure. In recent years many researchers in the fracture community have adopted a cohesive zone model for simulating crack propagation (based upon traction-separation relations) Sandia is implementing this model in its ASCI codes. There is, however, one important obstacle to using a cohesive zone modeling approach. At the present time traction-separation relations are chosen in an ad hoc manner. The goal of the present work is to determine a physical basis for Traction-Separation (T-U) relations. This report presents results of a program aimed at determining the dependence of such relations on adhesive and bulk properties. The work focused on epoxy/solid interfaces, although the approach is applicable to a broad range of materials. Asymmetric double cantilevered beam and free surface film nanoindentation fracture toughness tests were used to generate a unique set of data spanning length scales, applied mode mixities, and yield (plastic) zone constraint. The crucial roles of crack tip plastic zone size and interfacial adhesion were defined by varying epoxy layer thickness and using coupling agents or special self-assembled monolayers in preparing the samples. The nature of the yield zone was probed in collaborative experiments run at the Advanced Photon Source. This work provides an understanding of the major phenomena governing polymer/solid interfacial fracture and identifies the essential features that must be incorporated in a T-U based cohesive zone failure model. We believe that models using physically based T-U relations provide a more accurate and widely applicable description of interface cracking than models using ad hoc relations. Furthermore, these T-U relations provide an essential tool for using models to tailor interface properties to meet design needs

  13. Advanced dc-Traction-Motor Control System

    Science.gov (United States)

    Vittone, O.

    1985-01-01

    Motor-control concept for battery-powered vehicles includes stateof-the-art power-transistor switching and separate excitation of motor windings in traction and regenerative braking. Switching transistors and other components of power-conditioning subsystem operate under control of computer that coordinates traction, braking, and protective functions.

  14. Elastohydrodynamic Traction Properties of Seed Oils

    Science.gov (United States)

    The elastohydrodynamic traction coefficient (tc) properties of nine seed oils of varying chemical structures, PAO and hexadecane, were investigated using a ball-on disk traction apparatus. The seed oils were: castor oil, a triglyceride with hydroxyl functional group; jojoba, a monoglyceride; and s...

  15. Elastohydrodynamic (EHD) traction properties of seed oils

    Science.gov (United States)

    The elastohydrodynamic traction coefficient (tc) properties of nine seed oils of varying chemical structures, PAO and hexadecane, were investigated using a ball-on disk traction apparatus. The seed oils were: castor oil, a triglyceride with hydroxyl functional group; jojoba, a monoglyceride; and sev...

  16. CALCULATION OF A MECHANICAL CHARACTERISTIC OF ELECTRIC TRACTION MOTOR OF ELECTRIC VEHICLE

    Directory of Open Access Journals (Sweden)

    Phuong Le Ngo

    2017-01-01

    Full Text Available The traction characteristic of an electric vehicle is the main characteristic of mechanical system that reflects its key performance indicators. Implementation of the traction characteristic is based on controlling angular speed and torque of electric traction motor in an automatic control system. The static mechanical characteristic of an electric traction motor in an automatic control system is the most important characteristic that determines weight, size and operating characteristics of an electric traction motor and serves as the basis for design. The most common variants of constructive implementation of a traction electric drive are analyzed, and a scheme is chosen for further design. Lagrange’s equation for electric mechanical system with one degree of freedom is written in generalized coordinates. In order to determine the generalized forces, elementary operation of all moments influencing on a moving car has been calculated. The resulting equation of motion of the electric vehicle corresponding to the design scheme, as well as the expressions for calculation of characteristic points of static mechanical characteristics of traction motor (i.e. the maximum and minimum time, minimum power are obtained. In order to determine the nominal values of the angular velocity and the power of electric traction motor, a method based on ensuring the movement of the vehicle in the standard cycle has been developed. The method makes it possible to calculate characteristic points of the mechanical characteristic with the lowest possible power rating. The algorithm for calculation of mechanical characteristics of the motor is presented. The method was applied to calculate static mechanical characteristic of an electric traction motor for a small urban electric truck.

  17. Force-activatable biosensor enables single platelet force mapping directly by fluorescence imaging.

    Science.gov (United States)

    Wang, Yongliang; LeVine, Dana N; Gannon, Margaret; Zhao, Yuanchang; Sarkar, Anwesha; Hoch, Bailey; Wang, Xuefeng

    2018-02-15

    Integrin-transmitted cellular forces are critical for platelet adhesion, activation, aggregation and contraction during hemostasis and thrombosis. Measuring and mapping single platelet forces are desired in both research and clinical applications. Conventional force-to-strain based cell traction force microscopies have low resolution which is not ideal for cellular force mapping in small platelets. To enable platelet force mapping with submicron resolution, we developed a force-activatable biosensor named integrative tension sensor (ITS) which directly converts molecular tensions to fluorescent signals, therefore enabling cellular force mapping directly by fluorescence imaging. With ITS, we mapped cellular forces in single platelets at 0.4µm resolution. We found that platelet force distribution has strong polarization which is sensitive to treatment with the anti-platelet drug tirofiban, suggesting that the ITS force map can report anti-platelet drug efficacy. The ITS also calibrated integrin molecular tensions in platelets and revealed two distinct tension levels: 12-54 piconewton (nominal values) tensions generated during platelet adhesion and tensions above 54 piconewton generated during platelet contraction. Overall, the ITS is a powerful biosensor for the study of platelet mechanobiology, and holds great potential in antithrombotic drug development and assessing platelet activity in health and disease. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Asymmetry of activation of lateral abdominal muscles during the neurodevelopmental traction technique.

    Science.gov (United States)

    Gogola, Anna; Gnat, Rafał; Zaborowska, Małgorzata; Dziub, Dorota; Gwóźdź, Michalina

    2018-01-01

    The aim of the study was to evaluate the symmetry and pattern of activation of lateral abdominal muscles (LAM) in response to neurodevelopmental traction technique. Measurements of LAM thickness were performed in four experimental conditions: during traction with the force of 5% body weight (5% traction): 1) in neutral position, 2) in 20° posterior trunk inclination; during traction with the force of 15% body weight (15% traction): 3) in neutral position, 4) in 20° posterior trunk inclination. Thirty-seven healthy children participated in the study. Not applicable. To evaluate LAM activation level ultrasound technology was employed (two Mindray DP660 devices (Mindray, Shenzhen, China) with 75L38EA linear probes). An experiment with repeated measurements of the dependent variables was conducted. Side-to-side LAM activation asymmetry showed relatively high magnitude, however, significant difference was found only in case of the obliquus externus (OE) during stronger traction (P muscle differences were most pronounced between the OE and TrA (P muscles showing less intense activation. In statistical terms, the only signs of side-to-side asymmetry of LAM activation are visible in case of the OE, however, the magnitude of asymmetry is relatively high. The results allow to identify patterns of activation of LAM in children showing typical development that will serve as a reference in future studies in children with neurological disorder. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Wood : adhesives

    Science.gov (United States)

    A.H. Conner

    2001-01-01

    This chapter on wood adhesives includes: 1) Classification of wood adhesives 2) Thermosetting wood adhesives 3) Thermoplastic adhesives, 4) Wood adhesives based on natural sources 5) Nonconventional bonding of wood 6) Wood bonding.

  20. Integrated Traction Control Strategy for Distributed Drive Electric Vehicles with Improvement of Economy and Longitudinal Driving Stability

    Directory of Open Access Journals (Sweden)

    Xudong Zhang

    2017-01-01

    Full Text Available This paper presents an integrated traction control strategy (ITCS for distributed drive electric vehicles. The purpose of the proposed strategy is to improve vehicle economy and longitudinal driving stability. On high adhesion roads, economy optimization algorithm is applied to maximize motors efficiency by means of the optimized torque distribution. On low adhesion roads, a sliding mode control (SMC algorithm is implemented to guarantee the wheel slip ratio around the optimal slip ratio point to make full use of road adhesion capacity. In order to avoid the disturbance on slip ratio calculation due to the low vehicle speed, wheel rotational speed is taken as the control variable. Since the optimal slip ratio varies according to different road conditions, Bayesian hypothesis selection is utilized to estimate the road friction coefficient. Additionally, the ITCS is designed for combining the vehicle economy and stability control through three traction allocation cases: economy-based traction allocation, pedal self-correcting traction allocation and inter-axles traction allocation. Finally, simulations are conducted in CarSim and Matlab/Simulink environment. The results show that the proposed strategy effectively reduces vehicle energy consumption, suppresses wheels-skid and enhances the vehicle longitudinal stability and dynamic performance.

  1. Dry adhesives with sensing features

    International Nuclear Information System (INIS)

    Krahn, J; Menon, C

    2013-01-01

    Geckos are capable of detecting detachment of their feet. Inspired by this basic observation, a novel functional dry adhesive is proposed, which can be used to measure the instantaneous forces and torques acting on an adhesive pad. Such a novel sensing dry adhesive could potentially be used by climbing robots to quickly realize and respond appropriately to catastrophic detachment conditions. The proposed torque and force sensing dry adhesive was fabricated by mixing Carbon Black (CB) and Polydimethylsiloxane (PDMS) to form a functionalized adhesive with mushroom caps. The addition of CB to PDMS resulted in conductive PDMS which, when under compression, tension or torque, resulted in a change in the resistance across the adhesive patch terminals. The proposed design of the functionalized dry adhesive enables distinguishing an applied torque from a compressive force in a single adhesive pad. A model based on beam theory was used to predict the change in resistance across the terminals as either a torque or compressive force was applied to the adhesive patch. Under a compressive force, the sensing dry adhesive was capable of measuring compression stresses from 0.11 Pa to 20.9 kPa. The torque measured by the adhesive patch ranged from 2.6 to 10 mN m, at which point the dry adhesives became detached. The adhesive strength was 1.75 kPa under an applied preload of 1.65 kPa for an adhesive patch with an adhesive contact area of 7.07 cm 2 . (paper)

  2. Dry adhesives with sensing features

    Science.gov (United States)

    Krahn, J.; Menon, C.

    2013-08-01

    Geckos are capable of detecting detachment of their feet. Inspired by this basic observation, a novel functional dry adhesive is proposed, which can be used to measure the instantaneous forces and torques acting on an adhesive pad. Such a novel sensing dry adhesive could potentially be used by climbing robots to quickly realize and respond appropriately to catastrophic detachment conditions. The proposed torque and force sensing dry adhesive was fabricated by mixing Carbon Black (CB) and Polydimethylsiloxane (PDMS) to form a functionalized adhesive with mushroom caps. The addition of CB to PDMS resulted in conductive PDMS which, when under compression, tension or torque, resulted in a change in the resistance across the adhesive patch terminals. The proposed design of the functionalized dry adhesive enables distinguishing an applied torque from a compressive force in a single adhesive pad. A model based on beam theory was used to predict the change in resistance across the terminals as either a torque or compressive force was applied to the adhesive patch. Under a compressive force, the sensing dry adhesive was capable of measuring compression stresses from 0.11 Pa to 20.9 kPa. The torque measured by the adhesive patch ranged from 2.6 to 10 mN m, at which point the dry adhesives became detached. The adhesive strength was 1.75 kPa under an applied preload of 1.65 kPa for an adhesive patch with an adhesive contact area of 7.07 cm2.

  3. TRACTION RESISTANCE IN CHITOSAN TREATED COTTON

    Directory of Open Access Journals (Sweden)

    LOX Wouter

    2015-05-01

    Full Text Available Nowadays natural products interest has increased. However, when some products are included on textile fibers, they have no affinity and need some binders or other kind of auxiliaries to improve the yeld of the process, and some of them are not so natural as the product which are binding and consequently the “bio” definition is missed as some of them can be considered as highly pollutant. Chitosan is a common used bonding agent for cotton. It improves the antimicrobial and antifungal activity, improves wound healing and is a non-toxic bonding agent. The biopolymer used in this work is chitosan, which is a deacetylated derivative of chitin. These properties depend on the amount of deacetylation (DD and the Molecular weight (MW. Along with these improving properties, as it requires some acid pH to ve solved the treatment with chitosan can have some decreasing mechanical properties. The aim of that paper is to evaluate the change in breaking force of the treated samples and a change in elongation of those samples. It compared different amounts of concentration of chitosan with non treated cotton. The traction resistance test were performed on a dynamometer. The test was conducted according to the UNE EN ISO 13934-1 standard.

  4. Characterizing components of the Saw Palmetto Berry Extract (SPBE) on prostate cancer cell growth and traction

    International Nuclear Information System (INIS)

    Scholtysek, Carina; Krukiewicz, Aleksandra A.; Alonso, Jose-Luis; Sharma, Karan P.; Sharma, Pal C.; Goldmann, Wolfgang H.

    2009-01-01

    Saw Palmetto Berry Extract (SPBE) is applied for prostate health and treatment of urinary tract infections, nonbacterial prostitis and Benign Prostatic Hyperplasia (BPH) in man. An assumption is that SPBE affects tumor cell progression and migration in breast and prostate tissue. In this work, DU-145 cells were used to demonstrate that SPBE and its sterol components, β-sitosterol and stigmasterol, inhibit prostate cancer growth by increasing p53 protein expression and also inhibit carcinoma development by decreasing p21 and p27 protein expression. In the presence of cholesterol, these features are not only reversed but increased significantly. The results show for the first time the potential of SPBE, β-sitosterol and stigmasterol as potential anti-tumor agents. Since the protein p53 is also regarded as nuclear matrix protein facilitating actin cytoskeletal binding, 2D tractions were measured. The cell adhesion strength in the presence of SPBE, β-sitosterol and cholesterol and the observation was that the increase in p53 expression triggered an increase in the intracellular force generation. The results suggest a dual function of p53 in cells.

  5. Characterizing components of the Saw Palmetto Berry Extract (SPBE) on prostate cancer cell growth and traction.

    Science.gov (United States)

    Scholtysek, Carina; Krukiewicz, Aleksandra A; Alonso, José-Luis; Sharma, Karan P; Sharma, Pal C; Goldmann, Wolfgang H

    2009-02-13

    Saw Palmetto Berry Extract (SPBE) is applied for prostate health and treatment of urinary tract infections, nonbacterial prostitis and Benign Prostatic Hyperplasia (BPH) in man. An assumption is that SPBE affects tumor cell progression and migration in breast and prostate tissue. In this work, DU-145 cells were used to demonstrate that SPBE and its sterol components, beta-sitosterol and stigmasterol, inhibit prostate cancer growth by increasing p53 protein expression and also inhibit carcinoma development by decreasing p21 and p27 protein expression. In the presence of cholesterol, these features are not only reversed but increased significantly. The results show for the first time the potential of SPBE, beta-sitosterol and stigmasterol as potential anti-tumor agents. Since the protein p53 is also regarded as nuclear matrix protein facilitating actin cytoskeletal binding, 2D tractions were measured. The cell adhesion strength in the presence of SPBE, beta-sitosterol and cholesterol and the observation was that the increase in p53 expression triggered an increase in the intracellular force generation. The results suggest a dual function of p53 in cells.

  6. Integrated traction control strategy for distributed drive electric vehicles with improvement of economy and longitudinal driving stability

    OpenAIRE

    Zhang, Xudong; Göhlich, Dietmar

    2017-01-01

    This paper presents an integrated traction control strategy (ITCS) for distributed drive electric vehicles. The purpose of the proposed strategy is to improve vehicle economy and longitudinal driving stability. On high adhesion roads, economy optimization algorithm is applied to maximize motors efficiency by means of the optimized torque distribution. On low adhesion roads, a sliding mode control (SMC) algorithm is implemented to guarantee the wheel slip ratio around the optimal slip ratio po...

  7. Mechanism underlying bioinertness of self-assembled monolayers of oligo(ethyleneglycol)-terminated alkanethiols on gold: protein adsorption, platelet adhesion, and surface forces.

    Science.gov (United States)

    Hayashi, Tomohiro; Tanaka, Yusaku; Koide, Yuki; Tanaka, Masaru; Hara, Masahiko

    2012-08-07

    The mechanism underlying the bioinertness of the self-assembled monolayers of oligo(ethylene glycol)-terminated alkanethiol (OEG-SAM) was investigated with protein adsorption experiments, platelet adhesion tests, and surface force measurements with an atomic force microscope (AFM). In this work, we performed systematic analysis with SAMs having various terminal groups (-OEG, -OH, -COOH, -NH(2), and -CH(3)). The results of the protein adsorption experiment by the quartz crystal microbalance (QCM) method suggested that having one EG unit and the neutrality of total charges of the terminal groups are essential for protein-resistance. In particular, QCM with energy dissipation analyses indicated that proteins absorb onto the OEG-SAM via a very weak interaction compared with other SAMs. Contrary to the protein resistance, at least three EG units as well as the charge neutrality of the SAM are found to be required for anti-platelet adhesion. When the identical SAMs were formed on both AFM probe and substrate, our force measurements revealed that only the OEG-SAMs possessing more than two EG units showed strong repulsion in the range of 4 to 6 nm. In addition, we found that the SAMs with other terminal groups did not exhibit such repulsion. The repulsion between OEG-SAMs was always observed independent of solution conditions [NaCl concentration (between 0 and 1 M) and pH (between 3 and 11)] and was not observed in solution mixed with ethanol, which disrupts the three-dimensional network of the water molecules. We therefore concluded that the repulsion originated from structured interfacial water molecules. Considering the correlation between the above results, we propose that the layer of the structured interfacial water with a thickness of 2 to 3 nm (half of the range of the repulsion observed in the surface force measurements) plays an important role in deterring proteins and platelets from adsorption or adhesion.

  8. Particle adhesion and removal

    CERN Document Server

    Mittal, K L

    2015-01-01

    The book provides a comprehensive and easily accessible reference source covering all important aspects of particle adhesion and removal.  The core objective is to cover both fundamental and applied aspects of particle adhesion and removal with emphasis on recent developments.  Among the topics to be covered include: 1. Fundamentals of surface forces in particle adhesion and removal.2. Mechanisms of particle adhesion and removal.3. Experimental methods (e.g. AFM, SFA,SFM,IFM, etc.) to understand  particle-particle and particle-substrate interactions.4. Mechanics of adhesion of micro- and  n

  9. Traction-related problems after hip arthroscopy

    DEFF Research Database (Denmark)

    Frandsen, Lone; Lund, Bent; Grønbech Nielsen, Torsten

    2017-01-01

    . The questionnaire included questions on patients' perceptions of traction-related problems in the groin area, at the knee and ankle and how patients had coped with these problems. A total of 100 consecutive patients undergoing hip arthroscopy filled out the questionnaire. Primary findings of this study were that 74......% of patients reported some sort of traction-related problems after hip arthroscopy. About 32% of the patients had problems in the groin area and 49% of the patients complained of symptoms in the knee joint. A total of 37% of the patients had experienced problems from the traction boot in the ankle area....... The complications were found to be temporary and disappeared after 2-4 weeks. Five patients still had complaints after 3 months. All five patients had a pre-existing knee injury prior to undergoing hip arthroscopy. Traction-related problems after hip arthroscopy are a challenge and our study showed that 74...

  10. Traction-related problems after hip arthroscopy

    Science.gov (United States)

    Lund, Bent; Grønbech Nielsen, Torsten; Lind, Martin

    2017-01-01

    Abstract Traction-related problems are poorly described in the existing literature. The purpose of this prospective study was to describe traction-related problems and how patients perceive these problems. The study was a descriptive cohort study and data were collected from questionnaires and patient files. The questionnaire included questions on patients’ perceptions of traction-related problems in the groin area, at the knee and ankle and how patients had coped with these problems. A total of 100 consecutive patients undergoing hip arthroscopy filled out the questionnaire. Primary findings of this study were that 74% of patients reported some sort of traction-related problems after hip arthroscopy. About 32% of the patients had problems in the groin area and 49% of the patients complained of symptoms in the knee joint. A total of 37% of the patients had experienced problems from the traction boot in the ankle area. The complications were found to be temporary and disappeared after 2–4 weeks. Five patients still had complaints after 3 months. All five patients had a pre-existing knee injury prior to undergoing hip arthroscopy. Traction-related problems after hip arthroscopy are a challenge and our study showed that 74% of the patients reported traction-related problems. This is significantly higher than previously reported. The present study found a high rate of complaints from the knee and ankle joints that have not previously been reported. The presented data suggest the need for more pre-surgery patient information about possible traction-related problems. PMID:28630721

  11. Effective Maxillary Protraction with Tandem Traction Bow Appliance

    Directory of Open Access Journals (Sweden)

    Pravin Kumar S Marure

    2014-01-01

    Full Text Available Tandem traction bow appliance (TTBA promotes patient compliance, because it is more esthetic and comfortable than extraoral appliances. TTBA should be used only in case where maxillary deficiency and normal mandible is present. Advantages of it includes good oral hygiene, early treatment of any Class III malocclusion, optimal retention, distribution of the forces for protraction to all maxillary teeth, free mandibular movement. It can be used in conjunction with fixed appliances if necessary. This paper includes two case reports. The treatment results in both the cases demonstrated significant skeletal and dental response to TTBA therapy. Skeletal change was primarily a result of anterior movement of the maxilla.

  12. Traction Control Study for a Scaled Automated Robotic Car

    OpenAIRE

    Morton, Mark A.

    2004-01-01

    This thesis presents the use of sliding mode control applied to a 1/10th scale robotic car to operate at a desired slip. Controlling the robot car at any desired slip has a direct relation to the amount of force that is applied to the driving wheels based on road surface conditions. For this model, the desired traction/slip is maintained for a specific surface which happens to be a Lego treadmill platform. How the platform evolved and the robot car was designed are also covered. To parame...

  13. Active cell-matrix coupling regulates cellular force landscapes of cohesive epithelial monolayers

    Science.gov (United States)

    Zhao, Tiankai; Zhang, Yao; Wei, Qiong; Shi, Xuechen; Zhao, Peng; Chen, Long-Qing; Zhang, Sulin

    2018-03-01

    Epithelial cells can assemble into cohesive monolayers with rich morphologies on substrates due to competition between elastic, edge, and interfacial effects. Here we present a molecularly based thermodynamic model, integrating monolayer and substrate elasticity, and force-mediated focal adhesion formation, to elucidate the active biochemical regulation over the cellular force landscapes in cohesive epithelial monolayers, corroborated by microscopy and immunofluorescence studies. The predicted extracellular traction and intercellular tension are both monolayer size and substrate stiffness dependent, suggestive of cross-talks between intercellular and extracellular activities. Our model sets a firm ground toward a versatile computational framework to uncover the molecular origins of morphogenesis and disease in multicellular epithelia.

  14. Polymer adhesion predictions for oral dosage forms to enhance drug administration safety. Part 2: In vitro approach using mechanical force methods.

    Science.gov (United States)

    Drumond, Nélio; Stegemann, Sven

    2018-06-01

    Predicting the potential for unintended adhesion of solid oral dosage forms (SODF) to mucosal tissue is an important aspect that should be considered during drug product development. Previous investigations into low strength mucoadhesion based on particle interactions methods provided evidence that rheological measurements could be used to obtain valid predictions for the development of SODF coatings that can be safely swallowed. The aim of this second work was to estimate the low mucoadhesive strength properties of different polymers using in vitro methods based on mechanical forces and to identify which methods are more precise when measuring reduced mucoadhesion. Another aim was to compare the obtained results to the ones achieved with in vitro particle interaction methods in order to evaluate which methodology can provide stronger predictions. The combined results correlate between particle interaction methods and mechanical force measurements. The polyethylene glycol grades (PEG) and carnauba wax showed the lowest adhesive potential and are predicted to support safe swallowing. Hydroxypropyl methylcellulose (HPMC) along with high molecular grades of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) exhibited strong in vitro mucoadhesive strength. The combination of rheological and force tensiometer measurements should be considered when assessing the reduced mucoadhesion of polymer coatings to support safe swallowing of SODF. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Traction control of an electric vehicle based on nonlinear observers

    Directory of Open Access Journals (Sweden)

    Diego A. Aligia

    2017-12-01

    Full Text Available A traction control strategy for a four-wheel electric vehicle is proposed in this paper. The strategy is based on nonlinear observers which allows estimating the maximum force that can be transmitted to the road. Knowledge of the maximum force allows controlling the slip of the driving wheels, preventing the wheel’s slippage in low-grip surfaces. The proposed strategy also allows to avoid the undesired yaw moment in the vehicle which occurs when road conditions on either side of it are dierent. This improves the eciency and the control of the vehicle, avoiding possible losses of stability that can result in risks for its occupants. Both the proposed observer and the control strategy are designed based on a dynamic rotational model of the wheel and a brush force model. Simulation results are obtained based on a complete vehicle model on the Simulink/CarSim platform.

  16. Neutrophil adhesion and chemotaxis depend on substrate mechanics

    International Nuclear Information System (INIS)

    Jannat, Risat A; Hammer, Daniel A; Robbins, Gregory P; Ricart, Brendon G; Dembo, Micah

    2010-01-01

    Neutrophil adhesion to the vasculature and chemotaxis within tissues play critical roles in the inflammatory response to injury and pathogens. Unregulated neutrophil activity has been implicated in the progression of numerous chronic and acute diseases such as rheumatoid arthritis, asthma and sepsis. Cell migration of anchorage-dependent cells is known to depend on both chemical and mechanical interactions. Although neutrophil responses to chemical cues have been well characterized, little is known about the effect of underlying tissue mechanics on neutrophil adhesion and migration. To address this question, we quantified neutrophil migration and traction stresses on compliant hydrogel substrates with varying elasticity in a micromachined gradient chamber in which we could apply either a uniform concentration or a precise gradient of the bacterial chemoattractant fMLP. Neutrophils spread more extensively on substrates of greater stiffness. In addition, increasing the stiffness of the substrate leads to a significant increase in the chemotactic index for each fMLP gradient tested. As the substrate becomes stiffer, neutrophils generate higher traction forces without significant changes in cell speed. These forces are often displayed in pairs and focused in the uropod. Increases in the mean fMLP concentration beyond the K D of the receptor lead to a decrease in chemotactic index on all surfaces. Blocking with an antibody against β 2 -integrins leads to a significant reduction, but not an elimination, of directed motility on stiff materials, but no change in motility on soft materials, suggesting neutrophils can display both integrin-dependent and integrin-independent motility. These findings are critical for understanding how neutrophil migration may change in different mechanical environments in vivo and can be used to guide the design of migration inhibitors that more efficiently target inflammation.

  17. Neutrophil adhesion and chemotaxis depend on substrate mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Jannat, Risat A; Hammer, Daniel A [Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 South 33rd Street, Philadelphia, PA 19104 (United States); Robbins, Gregory P; Ricart, Brendon G [Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 311A Towne Building, 220 South 33rd Street, Philadelphia, PA 19104 (United States); Dembo, Micah, E-mail: hammer@seas.upenn.ed [Department of Biomedical Engineering, Boston University, 44 Cummington Street, Boston, MA 02215 (United States)

    2010-05-19

    Neutrophil adhesion to the vasculature and chemotaxis within tissues play critical roles in the inflammatory response to injury and pathogens. Unregulated neutrophil activity has been implicated in the progression of numerous chronic and acute diseases such as rheumatoid arthritis, asthma and sepsis. Cell migration of anchorage-dependent cells is known to depend on both chemical and mechanical interactions. Although neutrophil responses to chemical cues have been well characterized, little is known about the effect of underlying tissue mechanics on neutrophil adhesion and migration. To address this question, we quantified neutrophil migration and traction stresses on compliant hydrogel substrates with varying elasticity in a micromachined gradient chamber in which we could apply either a uniform concentration or a precise gradient of the bacterial chemoattractant fMLP. Neutrophils spread more extensively on substrates of greater stiffness. In addition, increasing the stiffness of the substrate leads to a significant increase in the chemotactic index for each fMLP gradient tested. As the substrate becomes stiffer, neutrophils generate higher traction forces without significant changes in cell speed. These forces are often displayed in pairs and focused in the uropod. Increases in the mean fMLP concentration beyond the K{sub D} of the receptor lead to a decrease in chemotactic index on all surfaces. Blocking with an antibody against {beta}{sub 2}-integrins leads to a significant reduction, but not an elimination, of directed motility on stiff materials, but no change in motility on soft materials, suggesting neutrophils can display both integrin-dependent and integrin-independent motility. These findings are critical for understanding how neutrophil migration may change in different mechanical environments in vivo and can be used to guide the design of migration inhibitors that more efficiently target inflammation.

  18. Trends in mica–mica adhesion reflect the influence of molecular details on long-range dispersion forces underlying aggregation and coalignment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dongsheng; Chun, Jaehun; Xiao, Dongdong; Zhou, Weijiang; Cai, Huacheng; Zhang, Lei; Rosso, Kevin M.; Mundy, Christopher J.; Schenter, Gregory K.; De Yoreo, James J.

    2017-07-05

    Oriented attachment of nanocrystalline subunits is recognized as a common crystallization pathway that is closely related to formation of nanoparticle superlattices, mesocrystals, and other kinetically stabilized structures. Approaching particles have been observed to rotate to achieve co-alignment while separated by nanometer-scale solvent layers. Little is known about the forces that drive co-alignment, particularly in this “solvent-separated” regime. To obtain a mechanistic understanding of this process, we used atomic force microscopy-based dynamic force spectroscopy with tips fabricated from oriented mica to measure the adhesion forces between mica (001) surfaces in electrolyte solutions as a function of orientation, temperature, electrolyte type, and electrolyte concentration. The results reveal a ~60° periodicity as well as a complex dependence on electrolyte concentration and temperature. A continuum model that considers the competition between electrostatic repulsion and van der Waals attraction, augmented by microscopic details that include surface separation, water structure, ion hydration, and charge regulation at the interface, qualitatively reproduces the observed trends and implies that dispersion forces are responsible for establishing co-alignment in the solvent-separated state.

  19. In situ atomic force microscopy studies of reversible light-induced switching of surface roughness and adhesion in azobenzene-containing PMMA films

    International Nuclear Information System (INIS)

    Mueller, M.; Gonzalez-Garcia, Y.; Pakula, C.; Zaporojtchenko, V.; Strunskus, T.; Faupel, F.; Herges, R.; Zargarani, D.; Magnussen, O.M.

    2011-01-01

    Thin films in the range 40-80 nm of a blend of PMMA with an azobenzene derivative have been studied directly during UV and blue light irradiation by atomic force microscopy (AFM), revealing highly reversible changes in the surface roughness and the film adhesion. UV light induces an ∼80% increase in surface roughness, whereas illumination by blue light completely reverses these changes. Based on the observed surface topography and transition kinetics a reversible mass flow mechanisms is suggested, where the polarity changes upon switching trigger a wetting-dewetting transition in a surface segregation layer of the chromophore. Similar AFM measurements of the pull-off force indicate a decrease upon UV and an increase after blue light illumination with a complex kinetic behavior: a rapid initial change, attributed to the change in the cis isomer fraction of the azobenzene derivative, and a more gradual change, indicative of slow structural reorganization.

  20. A facile and cost-effective approach to engineer surface roughness for preparation of large-scale superhydrophobic substrate with high adhesive force

    Science.gov (United States)

    Zhou, Bingpu; Tian, Jingxuan; Wang, Cong; Gao, Yibo; Wen, Weijia

    2016-12-01

    This study presents a convenient avenue to fabricate polydimethylsiloxane (PDMS) with controllable surface morphologies and wetting characteristics via standard molding technique. The templates with engineered surface roughness were simply prepared by combinations of microfluidics and photo-polymerization of N-Isopropylacrylamide (NIPAM). The surface morphology of mold could be adjusted via ultraviolet-curing duration or the grafting density, which means that the surface of PDMS sample replicated from the mold could also be easily controlled based on the proposed method. Furthermore, via multiple grafting and replication processes, we have successfully demonstrated that hydrophobicity properties of prepared PDMS samples could be swiftly enhanced to ∼154° with highly adhesive force with resident water droplets. The obtained PDMS samples exhibited well resistance to external mechanical deformation even up to 100 cycles. The proposed scheme is timesaving, cost-effective and suitable for large-scale production of superhydrophobic PDMS substrates. We believe that the presented approach can provide a promising method for preparing superhydrophobic surface with highly adhesive force for on-chip liquid transport, localized reaction, etc.

  1. Modeling of traction-coupling properties of wheel propulsor

    Science.gov (United States)

    Sakhapov, R. L.; Nikolaeva, R. V.; Gatiyatullin, M. H.; Makhmutov, M. M.

    2017-12-01

    In conditions of operation of aggregates on soils with low bearing capacity, the main performance indicators of their operation are determined by the properties of retaining the functional qualities of the propulsor. Therefore, the parameters of the anti-skid device can not be calculated by only one criterion. The equipment of propellers with anti-skid devices, which allow to reduce the compaction effect of the propulsion device on the soil, seems to be a rational solution to the problem of increasing traction and coupling properties of the driving wheels. The mathematical model is based on the study of the interaction of the driving wheel with anti-skid devices and a deformable bearing surface, which takes into account the wheel diameter, skid coefficient, the parameters of the anti-skid device, the physical and mechanical properties of the soil. As a basic mathematical model that determines the dependence of the coupling properties on the wheel parameters, the model obtained as a result of integration and reflecting the process of soil deformation from the shear stress is adopted. The total value of the resistance forces will determine the force of the hitch pressure on the horizontal soil layers, and the value of its deformation is the degree of wheel slippage. When the anti-skid devices interact with the soil, the traction capacity of the wheel is composed of shear forces, soil shear and soil deformation forces with detachable hooks. As a result of the interaction of the hook with the soil, the latter presses against the walls of the hook with the force equal to the sum of the hook load and the resistance to movement. During operation, the linear dimensions of the hook will decrease, which is not taken into account by the safety factor. Abrasive wear of the thickness of the hook is approximately proportional to the work of friction caused by the movement of the hook when inserted into the soil and slipping the wheel.

  2. ENERGY EFFICIENCY DETERMINATION OF LOADING-BACK SYSTEM OF ELECTRIC TRACTION MACHINES

    Directory of Open Access Journals (Sweden)

    A. M. Afanasov

    2014-03-01

    Full Text Available Purpose.Acceptance post-repair testsof electric traction machinesare conducted onloading-backstandsthat reducethe overall power costsfor the tests.Currentlya numberof possiblecircuit designs of loading-backsystems of electric machines are known, but there is nomethod of determiningtheir energy efficiency. This in turn makes difficult the choiceof rationaloptions. The purpose of the article is the development of the corresponding methodo-logy to make easier this process. Methodology. Expressions for determining theenergy efficiency ofa stand for testingof electric traction machineswere obtained using the generalizedscheme analysisof energy transformationsin the loading-backsystems of universal structure. Findings.Thetechnique wasoffered and the analytical expressions for determining the energy efficiency of loading-backsystemsof electric traction machines wereobtained. Energy efficiency coefficientofloading-backsystemisproposed to consider as the ratio of the total actionenergy of the mechanical and electromotive forces, providing anchors rotation and flowof currents in electric machines, which are being tested,to the total energy, consumed during the test from the external network. Originality. The concept was introduced and the analytical determination method of the energy efficiency of loading-backsystem in electric traction machines was offered. It differs by efficiency availability of power sources and converters, as well as energy efficiency factors of indirect methods of loss compensation. Practical value. The proposed technique of energy efficiency estimation of a loading-backsystemcan be used in solving the problem of rational options choice of schematics stands decisions for electric traction machines acceptance tests of main line and industrial transport.

  3. Substrate, focal adhesions, and actin filaments: a mechanical unit with a weak spot for mechanosensitive proteins

    International Nuclear Information System (INIS)

    Kirchenbuechler, David; Born, Simone; Kirchgessner, Norbert; Houben, Sebastian; Hoffmann, Bernd; Merkel, Rudolf

    2010-01-01

    Mechanosensing is a vital prerequisite for dynamic remodeling of focal adhesions and cytoskeletal structures upon substrate deformation. For example, tissue formation, directed cell orientation or cell differentiation are regulated by such mechanosensing processes. Focal adhesions and the actin cytoskeleton are believed to be involved in these processes, but where mechanosensing molecules are located and how elastic substrate, focal adhesions and the cytoskeleton couple with each other upon substrate deformation still remains obscure. To approach these questions we have developed a sensitive method to apply defined spatially decaying deformation fields to cells cultivated on ultrasoft elastic substrates and to accurately quantify the resulting displacements of the actin cytoskeleton, focal adhesions, as well as the substrate. Displacement fields were recorded in live cell microscopy by tracking either signals from fluorescent proteins or marker particles in the substrate. As model cell type we used myofibroblasts. These cells are characterized by highly stable adhesion and force generating structures but are still able to detect mechanical signals with high sensitivity. We found a rigid connection between substrate and focal adhesions. Furthermore, stress fibers were found to be barely extendable almost over their whole lengths. Plastic deformation took place only at the very ends of actin filaments close to focal adhesions. As a result, this area became elongated without extension of existing actin filaments by polymerization. Both ends of the stress fibers were mechanically coupled with detectable plastic deformations on either site. Interestingly, traction force dependent substrate deformation fields remained mostly unaffected even when stress fiber elongations were released. These data argue for a location of mechanosensing proteins at the ends of actin stress fibers and describe, except for these domains, the whole system to be relatively rigid for tensile

  4. Traction alopecia: A neglected entity in 2017

    Directory of Open Access Journals (Sweden)

    Christiana Oyinlola Akingbola

    2017-01-01

    Full Text Available Traction alopecia was first described in 1904 but is still a cause of scarring hair loss in young women worldwide. It is unique in being initially a reversible then an irreversible (scarring form of alopecia. Linked to tightly-pulled hairstyles, it is seen across all races. The pattern of hair loss depends on the style creating it but most commonly affects the frontotemporal hairline. There are some new examination findings associated with traction alopecia, which are traction folliculitis, the fringe sign and hair casts (pseudonits on dermatoscopy. These may prove key in prompting early specialist referral. The mainstay of current treatment is cessation of the contributing hairstyles. Camouflage, anti-inflammatory or growth-stimulating topical preparations are second line treatments. In later stages of severe traction alopecia hair transplantation may be the only effective treatment. The evidence basis for medical intervention with topical agents is anecdotal at best. Furthermore, additional research is required to clarify the pathogenesis of this biphasic alopecia. Until then, prompt diagnosis and identification of causative hairstyles are focus of current dermatological practice.

  5. Traction alopecia: the root of the problem

    Directory of Open Access Journals (Sweden)

    Billero V

    2018-04-01

    Full Text Available Victoria Billero, Mariya MitevaDepartment of Dermatology and Cutaneous Surgery, University of Miami School of Medicine, Miami, FL, USAAbstract: Traction alopecia (TA affects one-third of women of African descent who wear various forms of traumatic hairstyling for a prolonged period of time. The risk of TA is increased by the extent of pulling and duration of traction, as well as the use of chemical relaxation. The frequent use of tight buns or ponytails, the attachment of weaves or hair extensions, and tight braids (such as cornrows and dreadlocks are believed to be the highest risk hairstyles. TA can also occur in the setting of religious and occupational traumatic hairstyling. In its later stages, the disease may progress into an irreversible scarring alopecia if traumatic hairstyling continues without appropriate intervention. The most common clinical presentation includes marginal alopecia and non-marginal patchy alopecia. A clue to the clinical diagnosis is the preservation of the fringe sign as opposed to its loss in frontal fibrosing alopecia (FFA. Dermoscopy can be helpful in the diagnosis and can detect the ongoing traction by the presence of hair casts. Histopathology can distinguish TA from alopecia areata, FFA, and patchy central centrifugal cicatricial alopecia. Currently, there is no cure. Therefore, it is imperative that clinicians educate high-risk populations about TA and those practices that may convey the risk of hair loss. Keywords: hair loss, alopecia, dermoscopy, trichoscopy, traction alopecia, African-American 

  6. Denture Adhesives

    Science.gov (United States)

    ... Devices Products and Medical Procedures Dental Devices Denture Adhesives Share Tweet Linkedin Pin it More sharing options ... Wearers Reporting Problems to the FDA Background Denture adhesives are pastes, powders or adhesive pads that may ...

  7. Traction for low-back pain with or without sciatica.

    NARCIS (Netherlands)

    Clarke, J.A.; van Tulder, M.W.; Blomberg, S.E.; de Vet, H.C.W.; van der Heijden, G.J.; Bronfort, G.; Bouter, L.M.

    2007-01-01

    Background: Traction is used to treat low-back pain (LBP), often with other treatments. Objectives: To determine traction's effectiveness, compared to reference treatments, placebo, sham traction or no treatment for LBP. Search strategy: We searched CENTRAL (The Cochrane Library 2006, issue 4),

  8. The Determination of the Asynchronous Traction Motor Characteristics of Locomotive

    Directory of Open Access Journals (Sweden)

    Pavel Grigorievich Kolpakhchyan

    2017-01-01

    Full Text Available The article deals with the problem of the locomotive asynchronous traction motor control with the AC diesel-electric transmission. The limitations of the torque of the traction motor when powered by the inverter are determined. The recommendations to improve the use of asynchronous traction motor of locomotives with the AC diesel-electric transmission are given.

  9. 21 CFR 882.5960 - Skull tongs for traction.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Skull tongs for traction. 882.5960 Section 882...) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5960 Skull tongs for traction. (a) Identification. Skull tongs for traction is an instrument used to immobilize a patient with a...

  10. COMPARATIVE ANALYSIS OF CONVERTER STRUCTURES OF THE TRACTION DRIVE PROSPECTIVE MULTI-SYSTEM ELECTRIC LOCOMOTIVES WITH DC TRACTION MOTORS

    Directory of Open Access Journals (Sweden)

    A. M. Muha

    2009-03-01

    Full Text Available In the article the structured schemes of steady-state converter are offered for traction drive of promising multisystem electric locomotives with traction engines of direct current and their comparative analysis is conducted.

  11. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    Science.gov (United States)

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-04

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects.

  12. Optical tweezers for the measurement of binding forces: system description and application for the study of E. coli adhesion

    Science.gov (United States)

    Fallman, Erik G.; Schedin, Staffan; Andersson, Magnus J.; Jass, Jana; Axner, Ove

    2003-06-01

    Optical tweezers together with a position sensitive detection system allows measurements of forces in the pN range between micro-sized biological objects. A prototype force measurement system has been constructed around in inverted microscope with an argon-ion pumped Ti:sapphire laser as light source for optical trapping. A trapped particle in the focus of the high numerical aperture microscope-objective behaves like an omni-directional mechanical spring if an external force displaces it. The displacement from the equilibrium position is a measure of the exerted force. For position detection of the trapped particle (polystyrene beads), a He-Ne laser beam is focused a small distance below the trapping focus. An image of the bead appears as a distinct spot in the far field, monitored by a photosensitive detector. The position data is converted to a force measurement by a calibration procedure. The system has been used for measuring the binding forces between E-coli bacterial adhesin and their receptor sugars.

  13. Sub-micron magnetic patterns and local variations of adhesion force induced in non-ferromagnetic amorphous steel by femtosecond pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huiyan; Feng, Yuping [Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, E08193 (Spain); Nieto, Daniel [Microoptics and GRIN Optics Group, Applied Physics Department, University of Santiago de Compostela, E15782 Santiago de Compostela (Spain); García-Lecina, Eva [Unidad de Superficies Metálicas, IK4-CIDETEC, E20009 Donostia-San Sebastián Gipuzkoa (Spain); Mcdaniel, Clare [National Centre for Laser Applications, School of Physics, National University of Ireland, Galway (Ireland); Díaz-Marcos, Jordi [Unitat de Tècniques Nanomètriques, Centres Científics i Tecnològics, Universitat de Barcelona, E08028 Barcelona (Spain); Flores-Arias, María Teresa [Microoptics and GRIN Optics Group, Applied Physics Department, University of Santiago de Compostela, E15782 Santiago de Compostela (Spain); O’Connor, Gerard M. [National Centre for Laser Applications, School of Physics, National University of Ireland, Galway (Ireland); Baró, Maria Dolors [Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, E08193 (Spain); Pellicer, Eva, E-mail: eva.pellicer@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, E08193 (Spain); and others

    2016-05-15

    Highlights: • Formation of ripples after femtosecond pulsed laser irradiation (FSPLI) of metallic glass was studied. • Magnetic patterning at the surface of non-ferromagnetic amorphous steel was induced by FSPLI. • The origin of the generated ferromagnetism is the laser-induced devitrification. - Abstract: Periodic ripple and nanoripple patterns are formed at the surface of amorphous steel after femtosecond pulsed laser irradiation (FSPLI). Formation of such ripples is accompanied with the emergence of a surface ferromagnetic behavior which is not initially present in the non-irradiated amorphous steel. The occurrence of ferromagnetic properties is associated with the laser-induced devitrification of the glassy structure to form ferromagnetic (α-Fe and Fe{sub 3}C) and ferrimagnetic [(Fe,Mn){sub 3}O{sub 4} and Fe{sub 2}CrO{sub 4}] phases located in the ripples. The generation of magnetic structures by FSPLI turns out to be one of the fastest ways to induce magnetic patterning without the need of any shadow mask. Furthermore, local variations of the adhesion force, wettability and nanomechanical properties are also observed and compared to those of the as-cast amorphous alloy. These effects are of interest for applications (e.g., biological, magnetic recording, etc.) where both ferromagnetism and tribological/adhesion properties act synergistically to optimize material performance.

  14. Traction calculation of band conveyors using the ''Nairi-2'' computer

    Energy Technology Data Exchange (ETDEWEB)

    Kutlunin, V A; Livshis, A V; Pod' yemshchikov, A N

    1982-01-01

    An algorithm is described and a program is introduced for traction calculation of band conveyors using the ''Nairi-2'' computer. The calculation system of the conveyor is derived by means of dividing the closed loop of the band into straight sections, which are separated by drums. The number of sections depends on the number of drums, the bypass system of them by the band, the shape of the conveyor route and in each specific case, a specific number is chosen. The initial information for the computer is assigned by a matrix, each row of which consists of parameters of the corresponding section. As a result, the forces of the beginning and end of the sections are found, and the required output of the drive motors with observance of the conditions of non-slippage of the drive drums and limiting of the maximum slack of the band between rollers are also found. The program allows one to make traction calculations of band conveyors with any routing shape for any number and position of the drive drums.

  15. Reversible adhesion switching of porous fibrillar adhesive pads by humidity.

    Science.gov (United States)

    Xue, Longjian; Kovalev, Alexander; Dening, Kirstin; Eichler-Volf, Anna; Eickmeier, Henning; Haase, Markus; Enke, Dirk; Steinhart, Martin; Gorb, Stanislav N

    2013-01-01

    We report reversible adhesion switching on porous fibrillar polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) adhesive pads by humidity changes. Adhesion at a relative humidity of 90% was more than nine times higher than at a relative humidity of 2%. On nonporous fibrillar adhesive pads of the same material, adhesion increased only by a factor of ~3.3. The switching performance remained unchanged in at least 10 successive high/low humidity cycles. Main origin of enhanced adhesion at high humidity is the humidity-induced decrease in the elastic modulus of the polar component P2VP rather than capillary force. The presence of spongelike continuous internal pore systems with walls consisting of P2VP significantly leveraged this effect. Fibrillar adhesive pads on which adhesion is switchable by humidity changes may be used for preconcentration of airborne particulates, pollutants, and germs combined with triggered surface cleaning.

  16. Orthodontic Traction of Impacted Canine Using Cantilever

    OpenAIRE

    Nakandakari, Cláudia; Gonçalves, João Roberto; Cassano, Daniel Serra; Raveli, Taísa Boamorte; Bianchi, Jonas; Raveli, Dirceu Barnabé

    2016-01-01

    The impaction of the maxillary canines causes relevant aesthetic and functional problems. The multidisciplinary approach to the proper planning and execution of orthodontic traction of the element in question is essential. Many strategies are cited in the literature; among them is the good biomechanical control in order to avoid possible side effects. The aim of this paper is to present a case report in which a superior canine impacted by palatine was pulled out with the aid of the cantilever...

  17. Digital Model of Railway Electric Traction Lines

    Science.gov (United States)

    Garg, Rachana; Mahajan, Priya; Kumar, Parmod

    2017-08-01

    The characteristic impedance and propagation constant define the behavior of signal propagation over the transmission lines. The digital model for railway traction lines which includes railway tracks is developed, using curve fitting technique in MATLAB. The sensitivity of this model has been computed with respect to frequency. The digital sensitivity values are compared with the values of analog sensitivity. The developed model is useful for digital protection, integrated operation, control and planning of the system.

  18. Understanding the traction of tennis surfaces

    OpenAIRE

    Clarke, James; Carré, Matt; Richardson, Andrea; Yang, Zhijun; Damm, Loic; Dixon, Sharon

    2011-01-01

    The traction provided by a footwear-surface interaction can have an impact on player safety, performance and overall enjoyment of sport. Mechanical test methods used for the testing and categorisation of safe playing surfaces do not tend to simulate loads occurring during participation on the surface, and thus are unlikely to predict human response to the surface. For example, the pendulum system routinely employed by the International Tennis Federation (I.T.F.) utilises a standard rubber ‘fo...

  19. Functionally different pads on the same foot allow control of attachment: stick insects have load-sensitive "heel" pads for friction and shear-sensitive "toe" pads for adhesion.

    Directory of Open Access Journals (Sweden)

    David Labonte

    Full Text Available Stick insects (Carausius morosus have two distinct types of attachment pad per leg, tarsal "heel" pads (euplantulae and a pre-tarsal "toe" pad (arolium. Here we show that these two pad types are specialised for fundamentally different functions. When standing upright, stick insects rested on their proximal euplantulae, while arolia were the only pads in surface contact when hanging upside down. Single-pad force measurements showed that the adhesion of euplantulae was extremely small, but friction forces strongly increased with normal load and coefficients of friction were [Formula: see text] 1. The pre-tarsal arolium, in contrast, generated adhesion that strongly increased with pulling forces, allowing adhesion to be activated and deactivated by shear forces, which can be produced actively, or passively as a result of the insects' sprawled posture. The shear-sensitivity of the arolium was present even when corrected for contact area, and was independent of normal preloads covering nearly an order of magnitude. Attachment of both heel and toe pads is thus activated partly by the forces that arise passively in the situations in which they are used by the insects, ensuring safe attachment. Our results suggest that stick insect euplantulae are specialised "friction pads" that produce traction when pressed against the substrate, while arolia are "true" adhesive pads that stick to the substrate when activated by pulling forces.

  20. Orthodontic Traction of Impacted Canine Using Cantilever

    Directory of Open Access Journals (Sweden)

    Cláudia Nakandakari

    2016-01-01

    Full Text Available The impaction of the maxillary canines causes relevant aesthetic and functional problems. The multidisciplinary approach to the proper planning and execution of orthodontic traction of the element in question is essential. Many strategies are cited in the literature; among them is the good biomechanical control in order to avoid possible side effects. The aim of this paper is to present a case report in which a superior canine impacted by palatine was pulled out with the aid of the cantilever on the Segmented Arch Technique (SAT concept. A 14.7-year-old female patient appeared at clinic complaining about the absence of the upper right permanent canine. The proposed treatment prioritized the traction of the upper right canine without changing the occlusion and aesthetics. For this, it only installed the upper fixed appliance (Roth with slot 0.018, opting for SAT in order to minimize unwanted side effects. The use of cantilever to the traction of the upper right canine has enabled an efficient and predictable outcome, because it is of statically determined mechanics.

  1. Traction alopecia: the root of the problem.

    Science.gov (United States)

    Billero, Victoria; Miteva, Mariya

    2018-01-01

    Traction alopecia (TA) affects one-third of women of African descent who wear various forms of traumatic hairstyling for a prolonged period of time. The risk of TA is increased by the extent of pulling and duration of traction, as well as the use of chemical relaxation. The frequent use of tight buns or ponytails, the attachment of weaves or hair extensions, and tight braids (such as cornrows and dreadlocks) are believed to be the highest risk hairstyles. TA can also occur in the setting of religious and occupational traumatic hairstyling. In its later stages, the disease may progress into an irreversible scarring alopecia if traumatic hairstyling continues without appropriate intervention. The most common clinical presentation includes marginal alopecia and non-marginal patchy alopecia. A clue to the clinical diagnosis is the preservation of the fringe sign as opposed to its loss in frontal fibrosing alopecia (FFA). Dermoscopy can be helpful in the diagnosis and can detect the ongoing traction by the presence of hair casts. Histopathology can distinguish TA from alopecia areata, FFA, and patchy central centrifugal cicatricial alopecia. Currently, there is no cure. Therefore, it is imperative that clinicians educate high-risk populations about TA and those practices that may convey the risk of hair loss.

  2. Efeito da profundidade de trabalho das hastes sulcadoras de uma semeadora-adubadora na patinagem, na força de tração e no consumo de combustível de um trator agrícola Effects of work operation depth of shanks in a seeder-fertilizer on slip, traction force and fuel consumption of a tractor

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Zambillo Palma

    2010-10-01

    are unnecessary. However, there are many problems regarding compaction of the surface layers of soils due to machinery traffic and crop-livestock integration. The solution found by the farmers is the change of the double disc on the seeders for the shanks, which operate deeper. Therefore, this work aimed to evaluate different operation depths of the shank, analyzing the fuel consumption, traction force, slip index, draw-bar leverage, specific consumption of fuel and the theoretical field capacity of a tractor pulling a seeder-fertilizer over a soil compacted due to crop-livestock integration. The treatments were composed of four depths of the shanks, which were placed operating 100, 150, 200 and 250 mm deep. The experiments were carried out in randomized blocks design with four treatments and three repetitions at the Engineering Department of the Federal University of Lavras. The results showed that the increasing of operation depth of the shanks in a compacted soil increases the fuel consumption, the slip index and the leverage on the draw-bar. But when the shanks operated 50 mm beyond the most compacted layer, the traction force and the slip index have decreased, increasing the theoretical field capacity.

  3. Home Cervical Traction to Reduce Neck Pain in Fighter Pilots.

    Science.gov (United States)

    Chumbley, Eric M; O'Hair, Nicole; Stolfi, Adrienne; Lienesch, Christopher; McEachen, James C; Wright, Bruce A

    2016-12-01

    Most fighter pilots report cervical pain during their careers. Recommendations for remediation lack evidence. We sought to determine whether regular use of a home cervical traction device could decrease reported cervical pain in F-15C pilots. An institutional review board-approved, Health Insurance Portability and Accountability Act-compliant, controlled crossover study was undertaken with 21 male F-15C fighter pilots between February and June 2015. Of the 21 subjects, 12 completed 6 wk each of traction and control, while logging morning, postflying, and post-traction pain. Pain was compared with paired t-tests between the periods, from initial pain scores to postflying, and postflying to post-traction. In the traction phase, initial pain levels increased postflight, from 1.2 (0.7) to 1.6 (1.0) Subsequent post-traction pain levels decreased to 1.3 (0.9), with a corresponding linear decrease in pain relative to pain reported postflight. The difference in pain levels after traction compared to initial levels was not significant, indicating that cervical traction was effective in alleviating flying-related pain. Control pain increased postflight from 1.4 (0.9) to 1.9 (1.3). Daily traction phase pain was lower than the control, but insignificant. To our knowledge, this is the first study of home cervical traction to address fighter pilots' cervical pain. We found a small but meaningful improvement in daily pain rating when using cervical traction after flying. These results help inform countermeasure development for pilots flying high-performance aircraft. Further study should clarify the optimal traction dose and timing in relation to flying.Chumbley EM, O'Hair N, Stolfi A, Lienesch C, McEachen JC, Wright BA. Home cervical traction to reduce neck pain in fighter pilots. Aerosp Med Hum Perform. 2016; 87(12):1010-1015.

  4. Physics of adhesion

    International Nuclear Information System (INIS)

    Gerberich, W W; Cordill, M J

    2006-01-01

    Adhesion physics was relegated to the lowest echelons of academic pursuit until the advent of three seemingly disconnected events. The first, atomic force microscopy (AFM), eventually allowed fine-scale measurement of adhesive point contacts. The second, large-scale computational materials science, now permits both hierarchical studies of a few thousand atoms from first principles or of billions of atoms with less precise interatomic potentials. The third is a microelectronics industry push towards the nanoscale which has provided the driving force for requiring a better understanding of adhesion physics. In the present contribution, an attempt is made at conjoining these separate events into an updating of how theoretical and experimental approaches are providing new understanding of adhesion physics. While all material couples are briefly considered, the emphasis is on metal/semiconductor and metal/ceramic interfaces. Here, adhesion energies typically range from 1 to 100 J m -2 where the larger value is considered a practical work of adhesion. Experimental emphasis is on thin-film de-adhesion for 10 to 1000 nm thick films. For comparison, theoretical approaches from first principles quantum mechanics to embedded atom methods used in multi-scale modelling are utilized

  5. A case of traction retinal detachment in a patient with Gaucher disease.

    Science.gov (United States)

    Watanabe, Akira; Gekka, Tamaki; Arai, Kota; Tsuneoka, Hiroshi

    2017-01-01

    This is the first report of vitreous surgery for traction retinal detachment in a patient with type III Gaucher disease with multiple vitreous opacities. A 16-year-old boy who was diagnosed with Gaucher disease at age two and was undergoing enzyme replacement therapy presented with numerous white opacities of varying sizes in the vitreous bodies of both eyes. Visual acuity was 20/40 in the right eye and 20/2000 in the left eye. The retina of the left eye was completely detached, and vitreous surgery was performed. Liquefaction of the vitreous body was advanced, and the central part of the vitreous cavity contained almost no vitreous humor. The macular region was successfully aspirated with a vitreous cutter to form a posterior vitreous detachment. From the optic disk to the nasal side, however, posterior vitreous detachment formation was prevented by strong adhesions between the retina and the vitreous body. The traction retinal detachment of the posterior fundus improved after vitreous body resection alone. Traction retinal detachment may occur as a result of severe vitreous liquefaction in cases of Gaucher disease with numerous vitreous opacities.

  6. Degradation-mediated cellular traction directs stem cell fate in covalently crosslinked three-dimensional hydrogels

    Science.gov (United States)

    Khetan, Sudhir; Guvendiren, Murat; Legant, Wesley R.; Cohen, Daniel M.; Chen, Christopher S.; Burdick, Jason A.

    2013-05-01

    Although cell-matrix adhesive interactions are known to regulate stem cell differentiation, the underlying mechanisms, in particular for direct three-dimensional encapsulation within hydrogels, are poorly understood. Here, we demonstrate that in covalently crosslinked hyaluronic acid (HA) hydrogels, the differentiation of human mesenchymal stem cells (hMSCs) is directed by the generation of degradation-mediated cellular traction, independently of cell morphology or matrix mechanics. hMSCs within HA hydrogels of equivalent elastic moduli that permit (restrict) cell-mediated degradation exhibited high (low) degrees of cell spreading and high (low) tractions, and favoured osteogenesis (adipogenesis). Moreover, switching the permissive hydrogel to a restrictive state through delayed secondary crosslinking reduced further hydrogel degradation, suppressed traction, and caused a switch from osteogenesis to adipogenesis in the absence of changes to the extended cellular morphology. Furthermore, inhibiting tension-mediated signalling in the permissive environment mirrored the effects of delayed secondary crosslinking, whereas upregulating tension induced osteogenesis even in the restrictive environment.

  7. Force loading explains spatial sensing of ligands by cells

    Science.gov (United States)

    Oria, Roger; Wiegand, Tina; Escribano, Jorge; Elosegui-Artola, Alberto; Uriarte, Juan Jose; Moreno-Pulido, Cristian; Platzman, Ilia; Delcanale, Pietro; Albertazzi, Lorenzo; Navajas, Daniel; Trepat, Xavier; García-Aznar, José Manuel; Cavalcanti-Adam, Elisabetta Ada; Roca-Cusachs, Pere

    2017-12-01

    Cells can sense the density and distribution of extracellular matrix (ECM) molecules by means of individual integrin proteins and larger, integrin-containing adhesion complexes within the cell membrane. This spatial sensing drives cellular activity in a variety of normal and pathological contexts. Previous studies of cells on rigid glass surfaces have shown that spatial sensing of ECM ligands takes place at the nanometre scale, with integrin clustering and subsequent formation of focal adhesions impaired when single integrin-ligand bonds are separated by more than a few tens of nanometres. It has thus been suggested that a crosslinking ‘adaptor’ protein of this size might connect integrins to the actin cytoskeleton, acting as a molecular ruler that senses ligand spacing directly. Here, we develop gels whose rigidity and nanometre-scale distribution of ECM ligands can be controlled and altered. We find that increasing the spacing between ligands promotes the growth of focal adhesions on low-rigidity substrates, but leads to adhesion collapse on more-rigid substrates. Furthermore, disordering the ligand distribution drastically increases adhesion growth, but reduces the rigidity threshold for adhesion collapse. The growth and collapse of focal adhesions are mirrored by, respectively, the nuclear or cytosolic localization of the transcriptional regulator protein YAP. We explain these findings not through direct sensing of ligand spacing, but by using an expanded computational molecular-clutch model, in which individual integrin-ECM bonds—the molecular clutches—respond to force loading by recruiting extra integrins, up to a maximum value. This generates more clutches, redistributing the overall force among them, and reducing the force loading per clutch. At high rigidity and high ligand spacing, maximum recruitment is reached, preventing further force redistribution and leading to adhesion collapse. Measurements of cellular traction forces and actin flow speeds

  8. Protein adhesives

    Science.gov (United States)

    Charles R. Frihart; Linda F. Lorenz

    2018-01-01

    Nature uses a wide variety of chemicals for providing adhesion internally (e.g., cell to cell) and externally (e.g., mussels to ships and piers). This adhesive bonding is chemically and mechanically complex, involving a variety of proteins, carbohydrates, and other compounds.Consequently,the effect of protein structures on adhesive properties is only partially...

  9. Incorporation of soft shaped hydrogel sheets into microfluidic systems using a simple adhesion masking process

    Science.gov (United States)

    Young, Dylan C.; Newsome, Isabel G.; Scrimgeour, Jan

    2017-12-01

    We report the use of simple adhesion masking in fabricating shaped, photo-polymerizable hydrogel sheets with very small elastic moduli on glass substrates. Direct ink masking of surface crosslinking groups allows for low cost hydrogel patterning that is compatible with materials where crosslinking is both photo- and chemically initiated. Mechanical removal of the unwanted polymerized material reveals the shaped hydrogel. The mechanical properties of the shaped hydrogels were characterized by exposure to well-defined shear flow inside the microfluidic device. We show that hydrogel sheets with elastic moduli down to 7.5 Pa can be shaped with millimeter feature sizes using this approach. The shaped hydrogels are suitable for applications such as the detection of shear flow, cell culture, and traction force microscopy.

  10. Measuring Rock-Fluid Adhesion Directly

    Science.gov (United States)

    Tadmor, R.

    2017-12-01

    We show how to measure directly solid-liquid adhesion. We consider the normal adhesion, the work adhesion, and the lateral adhesion. The technique at the center of the method is Centrifugal Adhesion Balance (CAB) which allows coordinated manipulation of normal and lateral forces. For example: 1. It allows to induce an increase in the normal force which pulls on a liquid drop while keeping zero lateral force. This method mimics a drop that is subjected to a gravitational force that is gradually increasing. 2. It allows to increase the lateral force at zero normal force, mimicking zero gravity. From this one can obtain additional solid-liquid interaction parameters. When performing work of adhesion measurements, the values obtained are independent of drop size and are in agreement with theoretical predictions.

  11. Skeletal traction and intramedullary nailing cost-effectiveness

    African Journals Online (AJOL)

    In the operative group 24 patients had union with one delayed union while in the traction group 12 patients had union, 9 with mal union and 4 delayed union. Conclusion: Intramedullary nailing is more cost-effective than skeletal traction. It met the dominant strategy, because it was significantly less costly than skeletal ...

  12. Traction for low-back pain with or without sciatica

    NARCIS (Netherlands)

    Wegner, I.; Widyahehening, I.S.; van Tulder, M.W.; Blomberg, S.E.I.; de Vet, H.C.W.; Brønfort, G.; Bouter, L.M.; van der Heijden, G.J.

    2013-01-01

    Background Traction has been used to treat low-back pain (LBP), often in combination with other treatments. We included both manual and machine-delivered traction in this review. This is an update of a Cochrane review first published in 1995, and previously updated in 2006. Objectives To assess the

  13. Development of Traction Drive Motors for the Toyota Hybrid System

    Science.gov (United States)

    Kamiya, Munehiro

    Toyota Motor Corporation developed in 2005 a new hybrid system for a large SUV. This system included the new development of a high-speed traction drive motor achieving a significant increase in power weight ratio. This paper provides an overview of the hybrid system, discusses the characteristics required of a traction drive motor, and presents the technologies employed in the developed motor.

  14. Cost effectiveness of using surgery versus skeletal traction in ...

    African Journals Online (AJOL)

    The financial cost benefit of surgery was further complimented by better functional outcomes. Conclusion: The data indicates a cost advantage of managing femoral shaft fracture by surgery compared to traction. Furthermore the longer hospital stay in the traction group is associated with more malunion, limb deformity and ...

  15. Gecko adhesion pad: a smart surface?

    Science.gov (United States)

    Pesika, Noshir S.; Zeng, Hongbo; Kristiansen, Kai; Zhao, Boxin; Tian, Yu; Autumn, Kellar; Israelachvili, Jacob

    2009-11-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  16. Gecko adhesion pad: a smart surface?

    Energy Technology Data Exchange (ETDEWEB)

    Pesika, Noshir S [Chemical and Biomolecular Engineering Department, Tulane University, New Orleans, LA 70118 (United States); Zeng Hongbo [Chemical and Materials Engineering Department, University of Alberta, Edmonton, AB, T6G 2V4 (Canada); Kristiansen, Kai; Israelachvili, Jacob [Chemical Engineering Department, University of California, Santa Barbara, CA 93117 (United States); Zhao, Boxin [Chemical Engineering Department and Waterloo Institute of Nanotechnology, University of Waterloo, Ontario, N2L 3G1 (Canada); Tian Yu [State Key Laboratory of Tribology, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China); Autumn, Kellar, E-mail: npesika@tulane.ed [Department of Biology, Lewis and Clark College, Portland, OR 97219 (United States)

    2009-11-18

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  17. Gecko adhesion pad: a smart surface?

    International Nuclear Information System (INIS)

    Pesika, Noshir S; Zeng Hongbo; Kristiansen, Kai; Israelachvili, Jacob; Zhao, Boxin; Tian Yu; Autumn, Kellar

    2009-01-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  18. Influence of AC system design on the realisation of tractive efforts by high adhesion locomotives

    Science.gov (United States)

    Spiryagin, Maksym; Wolfs, Peter; Cole, Colin; Stichel, Sebastian; Berg, Mats; Manfred, Plöchl

    2017-08-01

    The main task for heavy haul railway operators is to reduce the cost of exported minerals and enhance the long-term viability of rail transport operations through increasing productivity by running longer and heavier trains. The common opinion is that this is achievable by means of implementation of high adhesion locomotives with advanced AC traction technologies. Modern AC high adhesion locomotives are very complex mechatronic systems and can be designed with two alternative traction topologies of either bogie or individual axle controls. This paper describes a modelling approach for these two types of AC traction systems with the application of an advanced co-simulation methodology, where an electrical system and a traction algorithm are modelled in Matlab/Simulink, and a mechanical system is modelled in a multibody software package. Although the paper concentrates on the analysis of the functioning for these two types of traction control systems, the choice of reference slip values also has an influence on the performance of both systems. All these design variations and issues have been simulated for various adhesion conditions at the wheel-rail interface and their influence on the high traction performance of a locomotive equipped with two three-axle bogies has been discussed.

  19. Análisis de la fuerza isométrica en la propulsión y tracción en slalom en silla de ruedas y su relación con el rendimiento y la clasificación funcional. [Isometric force in wheelchair slalom during traction and propulsion and their relationship with performance and functional classification].

    Directory of Open Access Journals (Sweden)

    Raúl Reina

    2013-10-01

    profiles of the Cerebral Palsy International Sports and Recreation Association, took part in the study (5 ♂ and 4 ♀. Participants performed two maximal isometric force tests (propulsion and traction with their competition wheelchairs in which maximum force (Fmax, average force (Fmed, execution time and time used to reach different Fmax percentages were recorded. In addition, participants carried out two specific performance tests: a 16 m linear sprint with an inversion door after 8 m; and two 4 m linear displacements with a zig-zag round trip. The measured variable was execution time using photocell gates. Significant differences were found between D3 and D4 in propulsion tests for Fmax (p = 0,007 and Fmean (p = 0,002, being this last one higher. Significant statistical differences were found between D2 and D3 in specific performance tests (inversion: p = 0,034 and zig-zag: p = 0,010, being D3 the quickest group. Results show a non-linear relationship between classification divisions and the performance.http://dx.doi.org/10.5232/ricyde2013.03402

  20. Electric vehicle regenerative antiskid braking and traction control system

    Science.gov (United States)

    Cikanek, Susan R.

    1995-01-01

    An antiskid braking and traction control system for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes one or more sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensors and determining if regenerative antiskid braking control, requiring hydrualic braking control, or requiring traction control are required. The processor then employs a control strategy based on the determined vehicle state and provides command signals to a motor controller to control the operation of the electric traction motor and to a brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative antiskid braking control, hydraulic braking control, and traction control.

  1. Alignment of displaced or impacted teeth with the traction chain.

    Science.gov (United States)

    Sander, Franz Martin; Sander, Christian; Sander, Franz Günter

    2006-07-01

    To align those teeth in the dental arch that cannot erupt or are displaced, they must be surgically exposed. After the traction device is attached, the tooth is again covered with the mucoperiosteal flap to protect the tissues involved. For this reason, the loss of this traction device must be absolutely avoided in order to prevent another surgical intervention. Here at the University of Ulm, we have developed and tested an optimized traction chain for that purpose. The chain is attached to the tooth with a laser-roughened pad applying the acid-etching technique. The chain links serve as fixation elements for traction devices such as elastic ligatures or piggyback archwires. At the same time, one can determine the distance covered by the tooth by the number of the erupting chain links. We demonstrate the clinical application of this traction device in two cases.

  2. Electric vehicle regenerative antiskid braking and traction control system

    Science.gov (United States)

    Cikanek, S.R.

    1995-09-12

    An antiskid braking and traction control system for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes one or more sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensors and determining if regenerative antiskid braking control, requiring hydraulic braking control, or requiring traction control are required. The processor then employs a control strategy based on the determined vehicle state and provides command signals to a motor controller to control the operation of the electric traction motor and to a brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative antiskid braking control, hydraulic braking control, and traction control. 10 figs.

  3. Reversible manipulation of the adhesive forces of TiO{sub 2}/polybenzoxazine nanoassembled coatings through UV irradiation and thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Sheng-Feng; Kao, Tzu-Hao [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 106, Taiwan, ROC (China); Cheng, Chih-Chia [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan, ROC (China); Chang, Chi-Jung [Department of Chemical Engineering, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan, ROC (China); Chen, Jem-Kun, E-mail: jkchen@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 106, Taiwan, ROC (China)

    2015-12-01

    Graphical abstract: We developed a simple approach, mixing TiO{sub 2} nanoparticles and 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (BA), to obtain a UV-responsive surfaces after thermal treatment. Because the wettability between TiO{sub 2} nanoparticles and BA, a nanoassembled structure was generated on the surface during the coating process. Results indicate that the mixing 30 wt% TiO{sub 2} nanoparticles into PBA matrix generated the superhydrophobic surface (static water contact angle > 150°) with ca. 1° of sliding angle. The superhydrophobic TiO{sub 2}/PBA nanoassembled surface can be converted by photocatalytic oxidation into a highly hydrophilic one (static water contact angle ∼ 0°) within five minimums. Interestingly, the hydrophilic surface can be converted back into a superhydrophobic surface by heat treatment. A water droplet can be transported among the surfaces that UV-irradiated for various times. Velocity of the droplet on the 15°-titled surface could be also manipulated with UV irradiation for various times. The correlations between PBA and TiO{sub 2} nanoparticles would provide insight into the designing and developing of light-responsive surfaces. - Highlights: • Nanoassembly of PBA and TiO{sub 2} NPs are generated with superhydrophobicity. • The superhydrophobicity can be converted to hydrophilic surface within 5 min. • The hydrophilic surface can be converted back into a superhydrophobic surface. • Adhesive force of the nanoassemblies can be manipulated by UV illumination time. - Abstract: In this study we mixed TiO{sub 2} nanoparticles (NPs) with 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (BA), as a precursor to a polybenzoxazine (PBA), to generate nanocomposite surfaces possessing low surface free energies. Because of extreme phase separation between the TiO{sub 2} NPs and BA, their mixtures featured nanoassembled structures on their surfaces. After thermal curing, we obtained PBA/TiO{sub 2} nanoassembled (PTN) surfaces possessing

  4. Electrochemical, atomic force microscopy and infrared reflection absorption spectroscopy studies of pre-formed mussel adhesive protein films on carbon steel for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan, E-mail: fanzhang@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Div. of Surface and Corrosion Science, Drottning Kristinas vaeg.51, SE-100 44 Stockholm (Sweden); Pan, Jinshan [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Div. of Surface and Corrosion Science, Drottning Kristinas vaeg.51, SE-100 44 Stockholm (Sweden); Claesson, Per Martin [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Div. of Surface and Corrosion Science, Drottning Kristinas vaeg.51, SE-100 44 Stockholm (Sweden); Institute for Surface Chemistry, P.O. Box 5607, SE-114 86 Stockholm (Sweden); Brinck, Tore [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Physical Chemistry, Division of Physical Chemistry, Teknikringen 36, SE-10044 Stockholm (Sweden)

    2012-10-01

    Electrochemical measurements, in situ and ex situ atomic force microscopy (AFM) experiments and infrared reflection absorption spectroscopy (IRAS) analysis were performed to investigate the formation and stability as well as corrosion protection properties of mussel adhesive protein (Mefp-1) films on carbon steel, and the influence of cross-linking by NaIO{sub 4} oxidation. The in situ AFM measurements show flake-like adsorbed protein aggregates in the film formed at pH 9. The ex situ AFM images indicate multilayer-like films and that the film becomes more compact and stable in NaCl solution after the cross-linking. The IRAS results reveal the absorption bands of Mefp-1 on carbon steel before and after NaIO{sub 4} induced oxidation of the pre-adsorbed protein. Within a short exposure time, a certain corrosion protection effect was noted for the pre-formed Mefp-1 film in 0.1 M NaCl solution. Cross-linking the pre-adsorbed film by NaIO{sub 4} oxidation significantly enhanced the protection efficiency by up to 80%. - Highlights: Black-Right-Pointing-Pointer Mussel protein was tested as 'green' corrosion protection strategy for steel. Black-Right-Pointing-Pointer At pH 9, the protein adsorbs on carbon steel and forms a multilayer-like film. Black-Right-Pointing-Pointer NaIO{sub 4} leads to structural changes and cross-linking of the protein film. Black-Right-Pointing-Pointer Cross-linking results in a dense and compact film with increased stability. Black-Right-Pointing-Pointer Cross-linking of preformed film significantly enhances the corrosion protection.

  5. Improved Adhesion and Compliancy of Hierarchical Fibrillar Adhesives.

    Science.gov (United States)

    Li, Yasong; Gates, Byron D; Menon, Carlo

    2015-08-05

    The gecko relies on van der Waals forces to cling onto surfaces with a variety of topography and composition. The hierarchical fibrillar structures on their climbing feet, ranging from mesoscale to nanoscale, are hypothesized to be key elements for the animal to conquer both smooth and rough surfaces. An epoxy-based artificial hierarchical fibrillar adhesive was prepared to study the influence of the hierarchical structures on the properties of a dry adhesive. The presented experiments highlight the advantages of a hierarchical structure despite a reduction of overall density and aspect ratio of nanofibrils. In contrast to an adhesive containing only nanometer-size fibrils, the hierarchical fibrillar adhesives exhibited a higher adhesion force and better compliancy when tested on an identical substrate.

  6. Stretchable, Adhesion-Tunable Dry Adhesive by Surface Wrinkling

    KAUST Repository

    Jeong, Hoon Eui

    2010-02-16

    We introduce a simple yet robust method of fabricating a stretchable, adhesion-tunable dry adhesive by combining replica molding and surface wrinkling. By utilizing a thin, wrinkled polydimethyl siloxane (PDMS) sheet with a thickness of 1 mm with built-in micropillars, active, dynamic control of normal and shear adhesion was achieved. Relatively strong normal (∼10.8 N/cm2) and shear adhesion (∼14.7 N/cm2) forces could be obtained for a fully extended (strained) PDMS sheet (prestrain of∼3%), whereas the forces could be rapidly reduced to nearly zero once the prestrain was released (prestrain of ∼0.5%). Moreover, durability tests demonstrated that the adhesion strength in both the normal and shear directions was maintained over more than 100 cycles of attachment and detachment. © 2010 American Chemical Society.

  7. Stretchable, Adhesion-Tunable Dry Adhesive by Surface Wrinkling

    KAUST Repository

    Jeong, Hoon Eui; Kwak, Moon Kyu; Suh, Kahp Y.

    2010-01-01

    We introduce a simple yet robust method of fabricating a stretchable, adhesion-tunable dry adhesive by combining replica molding and surface wrinkling. By utilizing a thin, wrinkled polydimethyl siloxane (PDMS) sheet with a thickness of 1 mm with built-in micropillars, active, dynamic control of normal and shear adhesion was achieved. Relatively strong normal (∼10.8 N/cm2) and shear adhesion (∼14.7 N/cm2) forces could be obtained for a fully extended (strained) PDMS sheet (prestrain of∼3%), whereas the forces could be rapidly reduced to nearly zero once the prestrain was released (prestrain of ∼0.5%). Moreover, durability tests demonstrated that the adhesion strength in both the normal and shear directions was maintained over more than 100 cycles of attachment and detachment. © 2010 American Chemical Society.

  8. Adhesion enhancement of biomimetic dry adhesives by nanoparticle in situ synthesis

    International Nuclear Information System (INIS)

    Díaz Téllez, J P; Harirchian-Saei, S; Li, Y; Menon, C

    2013-01-01

    A novel method to increase the adhesion strength of a gecko-inspired dry adhesive is presented. Gold nanoparticles are synthesized on the tips of the microfibrils of a polymeric dry adhesive to increase its Hamaker constant. Formation of the gold nanoparticles is qualitatively studied through a colour change in the originally transparent substance and quantitatively analysed using ultraviolet–visible spectrophotometry. A pull-off force test is employed to quantify the adhesion enhancement. Specifically, adhesion forces of samples with and without embedded gold nanoparticles are measured and compared. The experimental results indicate that an adhesion improvement of 135% can be achieved. (paper)

  9. Wheel Slip Control for Improving Traction-Ability and Energy Efficiency of a Personal Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Kanghyun Nam

    2015-07-01

    Full Text Available In this paper, a robust wheel slip control system based on a sliding mode controller is proposed for improving traction-ability and reducing energy consumption during sudden acceleration for a personal electric vehicle. Sliding mode control techniques have been employed widely in the development of a robust wheel slip controller of conventional internal combustion engine vehicles due to their application effectiveness in nonlinear systems and robustness against model uncertainties and disturbances. A practical slip control system which takes advantage of the features of electric motors is proposed and an algorithm for vehicle velocity estimation is also introduced. The vehicle velocity estimator was designed based on rotational wheel dynamics, measurable motor torque, and wheel velocity as well as rule-based logic. The simulations and experiments were carried out using both CarSim software and an experimental electric vehicle equipped with in-wheel-motors. Through field tests, traction performance and effectiveness in terms of energy saving were all verified. Comparative experiments with variations of control variables proved the effectiveness and practicality of the proposed control design.

  10. Cellular Adhesion and Adhesion Molecules

    OpenAIRE

    SELLER, Zerrin

    2014-01-01

    In recent years, cell adhesion and cell adhesion molecules have been shown to be important for many normal biological processes, including embryonic cell migration, immune system functions and wound healing. It has also been shown that they contribute to the pathogenesis of a large number of common human disorders, such as rheumatoid arthritis and tumor cell metastasis in cancer. In this review, the basic mechanisms of cellular adhesion and the structural and functional features of adhes...

  11. An advanced pitch change mechanism incorporating a hybrid traction drive

    Science.gov (United States)

    Steinetz, B. M.; Loewenthal, S. H.; Sargisson, D. F.; White, G.

    1984-01-01

    A design of a propeller pitch control mechanism is described that meets the demanding requirements of a high-power, advanced turboprop. In this application, blade twisting moment torque can be comparable to that of the main reduction gearbox output: precise pitch control, reliability and compactness are all at a premium. A key element in the design is a compact, high-ratio hybrid traction drive which offers low torque ripple and high torsional stiffness. The traction drive couples a high speed electric motor/alternator unit to a ball screw that actuates the blade control links. The technical merits of this arrangement and the performance characteristics of the traction drive are discussed.

  12. Improved throughput traction microscopy reveals pivotal role for matrix stiffness in fibroblast contractility and TGF-β responsiveness

    Science.gov (United States)

    Marinković, Aleksandar; Mih, Justin D.; Park, Jin-Ah; Liu, Fei

    2012-01-01

    Lung fibroblast functions such as matrix remodeling and activation of latent transforming growth factor-β1 (TGF-β1) are associated with expression of the myofibroblast phenotype and are directly linked to fibroblast capacity to generate force and deform the extracellular matrix. However, the study of fibroblast force-generating capacities through methods such as traction force microscopy is hindered by low throughput and time-consuming procedures. In this study, we improved at the detail level methods for higher-throughput traction measurements on polyacrylamide hydrogels using gel-surface-bound fluorescent beads to permit autofocusing and automated displacement mapping, and transduction of fibroblasts with a fluorescent label to streamline cell boundary identification. Together these advances substantially improve the throughput of traction microscopy and allow us to efficiently compute the forces exerted by lung fibroblasts on substrates spanning the stiffness range present in normal and fibrotic lung tissue. Our results reveal that lung fibroblasts dramatically alter the forces they transmit to the extracellular matrix as its stiffness changes, with very low forces generated on matrices as compliant as normal lung tissue. Moreover, exogenous TGF-β1 selectively accentuates tractions on stiff matrices, mimicking fibrotic lung, but not on physiological stiffness matrices, despite equivalent changes in Smad2/3 activation. Taken together, these results demonstrate a pivotal role for matrix mechanical properties in regulating baseline and TGF-β1-stimulated contraction of lung fibroblasts and suggest that stiff fibrotic lung tissue may promote myofibroblast activation through contractility-driven events, whereas normal lung tissue compliance may protect against such feedback amplification of fibroblast activation. PMID:22659883

  13. Mechanisms of adhesion in geckos.

    Science.gov (United States)

    Autumn, Kellar; Peattie, Anne M

    2002-12-01

    The extraordinary adhesive capabilities of geckos have challenged explanation for millennia, since Aristotle first recorded his observations. We have discovered many of the secrets of gecko adhesion, yet the millions of dry, adhesive setae on the toes of geckos continue to generate puzzling new questions and valuable answers. Each epidermally-derived, keratinous seta ends in hundreds of 200 nm spatular tips, permitting intimate contact with rough and smooth surfaces alike. Prior studies suggested that adhesive force in gecko setae was directly proportional to the water droplet contact angle (θ) , an indicator of the free surface energy of a substrate. In contrast, new theory suggests that adhesion energy between a gecko seta and a surface (W(GS)) is in fact proportional to (1 + cosθ), and only for θ > 60°. A reanalysis of prior data, in combination with our recent study, support the van der Waals hypothesis of gecko adhesion, and contradict surface hydrophobicity as a predictor of adhesion force. Previously, we and our collaborators measured the force production of a single seta. Initial efforts to attach a seta failed because of improper 3D orientation. However, by simulating the dynamics of gecko limbs during climbing (based on force plate data) we discovered that, in single setae, a small normal preload, combined with a 5 μm displacement yielded a very large adhesive force of 200 microNewton (μN), 10 times that predicted by whole-animal measurements. 6.5 million setae of a single tokay gecko attached maximally could generate 130 kg force. This raises the question of how geckos manage to detach their feet in just 15 ms. We discovered that simply increasing the angle that the setal shaft makes with the substrate to 30° causes detachment. Understanding how simultaneous attachment and release of millions of setae are controlled will require an approach that integrates levels ranging from molecules to lizards.

  14. Adhesion science

    CERN Document Server

    Comyn, John

    1997-01-01

    The use of adhesives is widespread and growing, and there are few modern artefacts, from the simple cereal packet, to the jumbo jet, that are without this means of joining. Adhesion Science provides an illuminating account of the science underlying the use of adhesives, a branch of chemical technology which is fundamental to the science of coatings and composite materials and to the performance of all types of bonded structures. This book guides the reader through the essential basic polymer science, and the chemistry of adhesives in use at present. It discusses surface preparation for adhesive bonding, and the use of primers and coupling agents. There is a detailed chapter on contact angles and what can be predicted from them. A simple guide on stress distribution joints and how this relates to testing is included. It also examines the interaction of adhesives and the environment, including an analysis of the resistance of joints to water, oxygen and ultra-violet light. Adhesion Science provides a comprehens...

  15. Resistência mecânica do solo e força de tração em hastes sulcadoras de semeadoras-adubadoras em sistema de integração lavoura-pecuária Mechanical resistance of soil and traction force by planter chisel type openers in crop-livestock system

    Directory of Open Access Journals (Sweden)

    Osmar Conte

    2008-12-01

    Full Text Available A integração lavoura-pecuária, realizada mediante a implantação de pastagens no inverno e a semeadura de milho ou soja no verão, constitui-se numa alternativa para a diversificação de atividades e ampliação dos lucros. Animais em pastejo, principalmente em áreas agrícolas manejadas sob semeadura direta, podem resultar na compactação adicional do solo, diagnosticada geralmente pelo aumento de resistência do solo à penetração (RP. Com o objetivo de avaliar a correlação entre RP e força de tração (FT medida em hastes sulcadoras de semeadoras-adubadoras, nos anos de 2004 e 2005, foi conduzido um experimento em São Miguel das Missões - RS, em Latossolo Vermelho (0.540 kg kg-1 de argila. Os tratamentos consistiram em quatro intensidades de pastejo, que resultaram em alturas de pastagem de 10; 20; 30 e 40 cm, e de testemunha sem pastejo, organizados em DBC, com três repetições. Avaliou-se a RP, no final do período de pastejo, e na semeadura da soja, obteve-se a FT exigida nas hastes sulcadoras de semeadoras-adubadoras. A RP e a FT aumentaram com o incremento na intensidade de pastejo. A correlação entre essas variáveis foi significativa, comprovando que é possível avaliar o estado de compactação do solo por meio da medição da FT requerida pelas hastes sulcadoras de semeadoras-adubadoras.The use of crop-livestock integration systems, with forage implantation during winter and corn or soybean sown during summer, has become an alternative to activity diversification while magnifying profits. Cattle grazing, mainly in agricultural areas under no-tillage, can result in additional soil compaction, which can usually be diagnosed by increases in soil resistance to penetration (RP. Aiming to evaluate the correlation between RP and traction force (FT measured with cutting shafts, in the years of 2004 and 2005, an experiment was conducted in São Miguel das Missões - RS, Brazil, in an Oxisoil (0.540 kg kg-1 clay content

  16. Cellular dynamics of bovine aortic smooth muscle cells measured using MEMS force sensors

    Science.gov (United States)

    Tsukagoshi, Takuya; Nguyen, Thanh-Vinh; Hirayama Shoji, Kayoko; Takahashi, Hidetoshi; Matsumoto, Kiyoshi; Shimoyama, Isao

    2018-04-01

    Adhesive cells perceive the mechanical properties of the substrates to which they adhere, adjusting their cellular mechanical forces according to their biological characteristics. This mechanical interaction subsequently affects the growth, locomotion, and differentiation of the cell. However, little is known about the detailed mechanism that underlies this interaction between adherent cells and substrates because dynamically measuring mechanical phenomena is difficult. Here, we utilize microelectromechamical systems force sensors that can measure cellular traction forces with high temporal resolution (~2.5 µs) over long periods (~3 h). We found that the cellular dynamics reflected physical phenomena with time scales from milliseconds to hours, which contradicts the idea that cellular motion is slow. A single focal adhesion (FA) generates an average force of 7 nN, which disappears in ms via the action of trypsin-ethylenediaminetetraacetic acid. The force-changing rate obtained from our measurements suggests that the time required for an FA to decompose was nearly proportional to the force acting on the FA.

  17. Functional Group Imaging by Adhesion AFM

    NARCIS (Netherlands)

    Berger, C.E.H.; Berger, C.E.H.; van der Werf, Kees; Kooyman, R.P.H.; de Grooth, B.G.; Greve, Jan

    1995-01-01

    Recently developed adhesion atomic force microscopy was used as a technique to map the spatial arrangement of chemical functional groups at a surface with a lateral resolution of 20 nm. The ratio of the adhesion forces for different functional groups can be compared with values determined from the

  18. Adaptive control system of dump truck traction electric drive

    Science.gov (United States)

    Bolshunova, O. M.; Korzhev, A. A.; Kamyshyan, A. M.

    2018-03-01

    The paper describes the operational factors that determine the accident rate of a quarry motor vehicle and assessment of their impact on the choice of the operation mode of the traction drive control system.

  19. Intravitreal injection of perfluoropropane for the treatment of vitreomacular traction

    Directory of Open Access Journals (Sweden)

    Xiao-Ping Wan

    2013-07-01

    Full Text Available AIM: To study the efficacy of a single intravitreal injection of perfluoropropane(C3F8in releasing vitreomacular traction. METHODS: Twelve eyes of 12 consecutive patients with vitreomacular traction received a single intravitreal injection of 0.3mL 100%(C3F8were retrospectively analyzed. The best corrected vision acuity and the neural epithelium thickness of central macular were observed. RESULTS: One month following treatment, vitreomacular traction was released in 5 eyes(42%, mean final visual acuity(VAimproved 0.04 and mean central foveal thickness decreased by 69μm. The vision acuity before and after treatment were 0.20±0.07, 0.25±0.04 respectively.CONCLUSION: Intravitreal C3F8 injection could offer a minimally invasive alternative to pars plana vitrectomy in patients with vitreomacular traction.

  20. THE FLOW ANALYSIS ABOUT TRACTION OF QUARRY TRAINS

    Directory of Open Access Journals (Sweden)

    G. K. Getman

    2010-04-01

    Full Text Available The method of determination of constituents of expense of electric power on traction of quarry trains is resulted in the article, and also the degree of their intercommunication with the mode of train motion is analysed.

  1. INTELLIGENT DIAGNOSTIC SYSTEM OF EMERGENCY SITUATIONS IN TRACTION SUBSTATIONS DC

    Directory of Open Access Journals (Sweden)

    Sh. N. Nasyrov

    2009-09-01

    Full Text Available In the article the architecture and algorithm of operating an expert system providing the efficiency of functioning the electric equipment for traction substation as well as the four-parameter belonging function are determined.

  2. Tractional retinal detachment in Usher syndrome type II.

    Science.gov (United States)

    Rani, Alka; Pal, Nikhil; Azad, Raj Vardhan; Sharma, Yog Raj; Chandra, Parijat; Vikram Singh, Deependra

    2005-08-01

    Retinal detachment is a rare complication in patients with retinitis pigmentosa. A case is reported of tractional retinal detachment in a patient with retinitis pigmentosa and sensorineural hearing loss, which was diagnosed as Usher syndrome type II. Because of the poor visual prognosis, the patient refused surgery in that eye. Tractional retinal detachment should be added to the differential diagnoses of visual loss in patients with retinitis pigmentosa.

  3. Modeling of Sylgard Adhesive Strength

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Ralph Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-03

    Sylgard is the name of a silicone elastomeric potting material manufactured by Dow Corning Corporation.1 Although the manufacturer cites its low adhesive strength as a feature of this product, thin layers of Sylgard do in fact have a non-negligible strength, which has been measured in recent tensile and shear debonding tests. The adhesive strength of thin layers of Sylgard potting material can be important in applications in which components having signi cantly di erent thermal expansion properties are potted together, and the potted assembly is subjected to temperature changes. The tensile and shear tractions developed on the potted surfaces of the components can cause signi cant internal stresses, particularly for components made of low-strength materials with a high area-to-volume ratio. This report is organized as follows: recent Sylgard debonding tests are rst brie y summarized, with particular attention to the adhesion between Sylgard and PBX 9501, and also between Sylgard and aluminum. Next, the type of numerical model that will be used to simulate the debonding behavior exhibited in these tests is described. Then the calibration of the debonding model will be illustrated. Finally, the method by which the model parameters are adjusted (scaled) to be applicable to other, non- tested bond thicknesses is summarized, and all parameters of the model (scaled and unscaled) are presented so that other investigators can reproduce all of the simulations described in this report as well as simulations of the application of interest.

  4. Integral Sensor Fault Detection and Isolation for Railway Traction Drive.

    Science.gov (United States)

    Garramiola, Fernando; Del Olmo, Jon; Poza, Javier; Madina, Patxi; Almandoz, Gaizka

    2018-05-13

    Due to the increasing importance of reliability and availability of electric traction drives in Railway applications, early detection of faults has become an important key for Railway traction drive manufacturers. Sensor faults are important sources of failures. Among the different fault diagnosis approaches, in this article an integral diagnosis strategy for sensors in traction drives is presented. Such strategy is composed of an observer-based approach for direct current (DC)-link voltage and catenary current sensors, a frequency analysis approach for motor current phase sensors and a hardware redundancy solution for speed sensors. None of them requires any hardware change requirement in the actual traction drive. All the fault detection and isolation approaches have been validated in a Hardware-in-the-loop platform comprising a Real Time Simulator and a commercial Traction Control Unit for a tram. In comparison to safety-critical systems in Aerospace applications, Railway applications do not need instantaneous detection, and the diagnosis is validated in a short time period for reliable decision. Combining the different approaches and existing hardware redundancy, an integral fault diagnosis solution is provided, to detect and isolate faults in all the sensors installed in the traction drive.

  5. Behavior of single lap composite bolted joint under traction loading: Experimental investigation

    Science.gov (United States)

    Awadhani, L. V.; Bewoor, Anand

    2018-04-01

    Composite bolted joints are preferred connection in the composite structures to facilitate the dismantling for the replacements/ maintenance work. The joint behavior under tractive forces has been studied in order to understand the safety of the structure designed. The main objective of this paper is to investigate the behavior of single-lap joints in carbon fiber reinforced epoxy composites under traction loading conditions. The experiments were designed to identify the effect of bolt diameter, stacking sequence and loading rate on the properties of the joint. The experimental results show that the parameters influence the joint performance significantly.

  6. Evaluation of Strategies to Reducing Traction Energy Consumption of Metro Systems Using an Optimal Train Control Simulation Model

    Directory of Open Access Journals (Sweden)

    Shuai Su

    2016-02-01

    Full Text Available Increasing attention is being paid to the energy efficiency in metro systems to reduce the operational cost and to advocate the sustainability of railway systems. Classical research has studied the energy-efficient operational strategy and the energy-efficient system design separately to reduce the traction energy consumption. This paper aims to combine the operational strategies and the system design by analyzing how the infrastructure and vehicle parameters of metro systems influence the operational traction energy consumption. Firstly, a solution approach to the optimal train control model is introduced, which is used to design the Optimal Train Control Simulator(OTCS. Then, based on the OTCS, the performance of some important energy-efficient system design strategies is investigated to reduce the trains’ traction energy consumption, including reduction of the train mass, improvement of the kinematic resistance, the design of the energy-saving gradient, increasing the maximum traction and braking forces, introducing regenerative braking and timetable optimization. As for these energy-efficient strategies, the performances are finally evaluated using the OTCS with the practical operational data of the Beijing Yizhuang metro line. The proposed approach gives an example to quantitatively analyze the energy reduction of different strategies in the system design procedure, which may help the decision makers to have an overview of the energy-efficient performances and then to make decisions by balancing the costs and the benefits.

  7. THE EIGHT-WHEEL LOCOMOTIVE DC3 WITH THE SECOND TYPE OF RATING UNLOADING AND ADDITIONAL LOADING OF WHEELS AND DEFLECTIONS SPRING SUSPENSION DURING TRACTION EFFORTS TRANSFER FROM BOGIES TO BODY WITH USING RECLINING TRACTIONS

    Directory of Open Access Journals (Sweden)

    V. A. Bratash

    2010-11-01

    Full Text Available In the article the calculation formulas for determination of unloadings (finishings loadings of wheels and bendings of a spring suspension of 8-wheel electric locomotive DS 3 with the hauling transmission of the second kind at the transmission of tractive forces from the bogies to the body through sloping tractions are presented. Numerical calculations are executed on the example of mainline freight-and-passenger electric locomotive DS 3.

  8. Traction for low-back pain with or without sciatica.

    Science.gov (United States)

    Wegner, Inge; Widyahening, Indah S; van Tulder, Maurits W; Blomberg, Stefan E I; de Vet, Henrica Cw; Brønfort, Gert; Bouter, Lex M; van der Heijden, Geert J

    2013-08-19

    Traction has been used to treat low-back pain (LBP), often in combination with other treatments. We included both manual and machine-delivered traction in this review. This is an update of a Cochrane review first published in 1995, and previously updated in 2006. To assess the effects of traction compared to placebo, sham traction, reference treatments and no treatment in people with LBP. We searched the Cochrane Back Review Group Specialized Register, the Cochrane Central Register of Controlled Trials (2012, Issue 8), MEDLINE (January 2006 to August 2012), EMBASE (January 2006 to August 2012), CINAHL (January 2006 to August 2012), and reference lists of articles and personal files. The review authors are not aware of any important new randomized controlled trial (RCTs) on this topic since the date of the last search. RCTs involving traction to treat acute (less than four weeks' duration), subacute (four to 12 weeks' duration) or chronic (more than 12 weeks' duration) non-specific LBP with or without sciatica. Two review authors independently performed study selection, risk of bias assessment and data extraction. As there were insufficient data for statistical pooling, we performed a descriptive analysis. We did not find any case series that identified adverse effects, therefore we evaluated adverse effects that were reported in the included studies. We included 32 RCTs involving 2762 participants in this review. We considered 16 trials, representing 57% of all participants, to have a low risk of bias based on the Cochrane Back Review Group's 'Risk of bias' tool.For people with mixed symptom patterns (acute, subacute and chronic LBP with and without sciatica), there was low- to moderate-quality evidence that traction may make little or no difference in pain intensity, functional status, global improvement or return to work when compared to placebo, sham traction or no treatment. Similarly, when comparing the combination of physiotherapy plus traction with

  9. Adhesion molecules

    CERN Document Server

    Preedy, Victor R

    2016-01-01

    This book covers the structure and classification of adhesion molecules in relation to signaling pathways and gene expression. It discusses immunohistochemical localization, neutrophil migration, and junctional, functional, and inflammatory adhesion molecules in pathologies such as leukocyte decompression sickness and ischemia reperfusion injury. Highlighting the medical applications of current research, chapters cover diabetes, obesity, and metabolic syndrome; hypoxia; kidney disease; smoking, atrial fibrillation, and heart disease, the brain and dementia; and tumor proliferation. Finally, it looks at molecular imaging and bioinformatics, high-throughput technologies, and chemotherapy.

  10. Maximum Safety Regenerative Power Tracking for DC Traction Power Systems

    Directory of Open Access Journals (Sweden)

    Guifu Du

    2017-02-01

    Full Text Available Direct current (DC traction power systems are widely used in metro transport systems, with running rails usually being used as return conductors. When traction current flows through the running rails, a potential voltage known as “rail potential” is generated between the rails and ground. Currently, abnormal rises of rail potential exist in many railway lines during the operation of railway systems. Excessively high rail potentials pose a threat to human life and to devices connected to the rails. In this paper, the effect of regenerative power distribution on rail potential is analyzed. Maximum safety regenerative power tracking is proposed for the control of maximum absolute rail potential and energy consumption during the operation of DC traction power systems. The dwell time of multiple trains at each station and the trigger voltage of the regenerative energy absorbing device (READ are optimized based on an improved particle swarm optimization (PSO algorithm to manage the distribution of regenerative power. In this way, the maximum absolute rail potential and energy consumption of DC traction power systems can be reduced. The operation data of Guangzhou Metro Line 2 are used in the simulations, and the results show that the scheme can reduce the maximum absolute rail potential and energy consumption effectively and guarantee the safety in energy saving of DC traction power systems.

  11. [PVD-silicoating before cementation of zirconia-based knee prostheses effects better cement adhesion and lower aseptic loosening rates].

    Science.gov (United States)

    Marx, R; Faramarzi, R; Oberbach, T; Begand, S; Grätz, N; Wirtz, D C

    2012-02-01

    CoCrMo alloys are contraindicated for allergy patients. For these patients, cemented or uncemented prostheses made of titanium alloy are indicated. Uncemented prostheses, however, have low primary retention, particularly the tibial components of knee joint prostheses because of the lack of a positive locking. Therefore, for knee replacement cemented CoCrMo prostheses may be suitable also for allergy sufferers if these are masked by ZrN or TiNbN layers. Alternatively the CoCrMo alloy may be replaced by high-strength oxide ceramics. For adhesion of bone cement to the ceramic surface, however, only inefficient mechanical retention spots are exposed as compared with a metal surface. Undercuts generated by corundum blasting, although highly efficient on a CoCrMo surface, are not such efficient centres on a ceramic surface due to its brittleness. Therefore, the mechanical component of retention is significantly reduced. When specific adhesion between bone cement and surface does not exist due to physical and chemical forces, the hydrolytic stability will be insufficient. Micromotions are promoted and early aseptic loosening is predictable. Silicoating of the ceramic surface will allow specific adhesion and can result in better hydrolytic stability of bonding. In order to evaluate the effectiveness of silicoating the bond strengths of blasted (mean size of corundum grains 50 µm) and silicate layered alumina-toughened zirconia (ATZ) surfaces were compared with "as fired" surfaces by utilising TiAlV probes (diameter 6 mm) for traction-adhesive strength testing. Samples machined out of CoCrMo alloy were utilised for reference. After preparing the samples for traction-adhesive strength testing (sequence: substrate, silicate and silane, protective lacquer [PolyMA], bone cement, TiAlV probe) they were aged up to 360 days at 37 °C in Ringer's solution. The bond strengths observed for all ageing intervals were well above 20 MPa and much higher and more hydrolytically

  12. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    , which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to significantly...... tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion...... is the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental parameters...

  13. The Simulation of the Traction Drive with Middle-Frequency Transformer

    Directory of Open Access Journals (Sweden)

    Pavel Drabek

    2008-01-01

    Full Text Available This paper presents research motivated by industrial demand for special traction drive topology devoted to minimization of traction transformer weight against topology with classical 50Hz traction transformer. The special traction drive topology for AC power systems consists of input high voltage trolley converter (single phase matrix converter –middle frequency transformer - output converter - traction motor has been described. The main attention has been given tothe control algorithm of the traction topology (inserting of NULL vector of matrix converter and Two-value control ofsecondary active rectifier.

  14. Contact traction analysis for profile change during coining process

    International Nuclear Information System (INIS)

    Kim, Hyung Kyu; Yoon, Kyung Ho; Kang, Heung Seok; Song, Kee Nam

    2002-01-01

    Contact tractions are analysed in the case of the change in contact profile occurring during the coining process of a thin strip material. The changed profile is assumed as a concave circular arc in the central part of the contact region which is smoothly connected with convex circular arcs at both sides, referring to the actual measurement of the coined material. The profile is discretized and the known solutions of singular integral equations are used. Since the contact profile affects the contact traction and relevant tribological behaviour (e.g. wear) as well, an accurate definition of the profile is necessary in the analysis of material failure. Parametric study is conducted with the variation of the radii and distance of the arcs, which defines the height difference between the summits of the arcs. Considered is the contact profile, which can give the negligible variation of the traction in comparison with that before the coining process

  15. A modification of the maitland roll top traction table.

    Science.gov (United States)

    Kneipp, K

    1975-03-01

    This modification of the Maitland Roll Top Traction Table (Maitland, 1973) differs from the original as follows: 1. The two weight-bearing leaves are enclosed by a "guide frame" and the "U-piece" of the original is replaced by a hinged "gate" at the foot, which can be opened downwards for lumbar traction, or can be locked to restrain the leaves when the table is required for other purposes. 2. Four rollers of light steel replace the wooden dowels. 3. The modified table in use by the author is held by a floor peg, and is set up be-between two walls 10' 6″ apart which provide purchase points for traction. Alternatively, purchase at the head end can be taken by hooks attached to the table itself. 4. The design permits a six-foot plinth to be used. Copyright © 1975 Australian Physiotherapy Association. Published by . All rights reserved.

  16. Traction sheave elevator, hoisting unit and machine space

    Science.gov (United States)

    Hakala, Harri; Mustalahti, Jorma; Aulanko, Esko

    2000-01-01

    Traction sheave elevator consisting of an elevator car moving along elevator guide rails, a counterweight moving along counterweight guide rails, a set of hoisting ropes (3) on which the elevator car and counterweight are suspended, and a drive machine unit (6) driving a traction sheave (7) acting on the hoisting ropes (3) and placed in the elevator shaft. The drive machine unit (6) is of a flat construction. A wall of the elevator shaft is provided with a machine space with its open side facing towards the shaft, the essential parts of the drive machine unit (6) being placed in the space. The hoisting unit (9) of the traction sheave elevator consists of a substantially discoidal drive machine unit (6) and an instrument panel (8) mounted on the frame (20) of the hoisting unit.

  17. THE MEASUREMENT ELECTROMAGNETIC INTERFERENCE IN THE REVERSE TRACTION NETWORK

    Directory of Open Access Journals (Sweden)

    T. M. Serdiuk

    2009-09-01

    Full Text Available The original automated method of measurement of electrical noise in the return electric-traction network is proposed. It is realized on the base of car-laboratory “Automatics, telemechanics and communication”. The mathematic model of return electric-traction network is developed to scientific bases of automated measurement. It allows us obtaining the mathematic expressions for change of voltage and current harmonics in the rail net and taking into account the inhomogeneity of lines for the following analytic determination of a source of electric noise.

  18. Simple traction-immobilization device for CT scanners

    International Nuclear Information System (INIS)

    Robertson, J.; Federle, M.P.

    1983-01-01

    Successful computed tomographic (CT) scanning of acutely ill or traumatized patients often requires immobilization or traction of the extremities. Existing medical appliances and external fixation devices often are cumbersome, produce technical artifacts, or are uncomfortable for patients. This paper describes a traction-immobilization device that overcomes many of these difficulties. The authors have used this device successfully in several hundred cases and found that it markedly facilitated patient comfort and throughput. Construction is simple and inexpensive, using materials available in most hardware stores

  19. Temperature control of power semiconductor devices in traction applications

    Science.gov (United States)

    Pugachev, A. A.; Strekalov, N. N.

    2017-02-01

    The peculiarity of thermal management of traction frequency converters of a railway rolling stock is highlighted. The topology and the operation principle of the automatic temperature control system of power semiconductor modules of the traction frequency converter are designed and discussed. The features of semiconductors as an object of temperature control are considered; the equivalent circuit of thermal processes in the semiconductors is suggested, the power losses in the two-level voltage source inverters are evaluated and analyzed. The dynamic properties and characteristics of the cooling fan induction motor electric drive with the scalar control are presented. The results of simulation in Matlab are shown for the steady state of thermal processes.

  20. Molybdenum protective coatings adhesion to steel substrate

    Science.gov (United States)

    Blesman, A. I.; Postnikov, D. V.; Polonyankin, D. A.; Teplouhov, A. A.; Tyukin, A. V.; Tkachenko, E. A.

    2017-06-01

    Protection of the critical parts, components and assemblies from corrosion is an urgent engineering problem and many other industries. Protective coatings’ forming on surface of metal products is a promising way of corrosionprevention. The adhesion force is one of the main characteristics of coatings’ durability. The paper presents theoretical and experimental adhesion force assessment for coatings formed by molybdenum magnetron sputtering ontoa steel substrate. Validity and reliability of results obtained by simulation and sclerometry method allow applying the developed model for adhesion force evaluation in binary «steel-coating» systems.

  1. Vaginal epithelial cells regulate membrane adhesiveness to co-ordinate bacterial adhesion.

    Science.gov (United States)

    Younes, Jessica A; Klappe, Karin; Kok, Jan Willem; Busscher, Henk J; Reid, Gregor; van der Mei, Henny C

    2016-04-01

    Vaginal epithelium is colonized by different bacterial strains and species. The bacterial composition of vaginal biofilms controls the balance between health and disease. Little is known about the relative contribution of the epithelial and bacterial cell surfaces to bacterial adhesion and whether and how adhesion is regulated over cell membrane regions. Here, we show that bacterial adhesion forces with cell membrane regions not located above the nucleus are stronger than with regions above the nucleus both for vaginal pathogens and different commensal and probiotic lactobacillus strains involved in health. Importantly, adhesion force ratios over membrane regions away from and above the nucleus coincided with the ratios between numbers of adhering bacteria over both regions. Bacterial adhesion forces were dramatically decreased by depleting the epithelial cell membrane of cholesterol or sub-membrane cortical actin. Thus, epithelial cells can regulate membrane regions to which bacterial adhesion is discouraged, possibly to protect the nucleus. © 2015 John Wiley & Sons Ltd.

  2. Adhesive Strength of dry Adhesive Structures Depending on the Thickness of Metal Coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gyu Hye; Kwon, Da Som; Kim, Mi Jung; Kim, Su Hee; Yoon, Ji Won; An, Tea Chang; Hwang, Hui Yun [Andong National Univ., Andong (Korea, Republic of)

    2016-07-15

    Recently, engineering applications have started to adopt solutions inspired by nature. The peculiar adhesive properties of gecko skin are an example, as they allow the animal to move freely on vertical walls and even on ceilings. The high adhesive forces between gecko feet and walls are due to the hierarchical microscopical structure of the skin. In this study, the effect of metal coatings on the adhesive strength of synthetic, hierarchically structured, dry adhesives was investigated. Synthetic dry adhesives were fabricated using PDMS micro-molds prepared by photolithography. Metal coatings on synthetic dry adhesives were formed by plasma sputtering. Adhesive strength was measured by pure shear tests. The highest adhesion strengths were found with coatings composed of 4 nm thick layers of Indium, 8 nm thick layers of Zinc and 6 nm thick layers of Gold, respectively.

  3. Adhesive Strength of dry Adhesive Structures Depending on the Thickness of Metal Coating

    International Nuclear Information System (INIS)

    Kim, Gyu Hye; Kwon, Da Som; Kim, Mi Jung; Kim, Su Hee; Yoon, Ji Won; An, Tea Chang; Hwang, Hui Yun

    2016-01-01

    Recently, engineering applications have started to adopt solutions inspired by nature. The peculiar adhesive properties of gecko skin are an example, as they allow the animal to move freely on vertical walls and even on ceilings. The high adhesive forces between gecko feet and walls are due to the hierarchical microscopical structure of the skin. In this study, the effect of metal coatings on the adhesive strength of synthetic, hierarchically structured, dry adhesives was investigated. Synthetic dry adhesives were fabricated using PDMS micro-molds prepared by photolithography. Metal coatings on synthetic dry adhesives were formed by plasma sputtering. Adhesive strength was measured by pure shear tests. The highest adhesion strengths were found with coatings composed of 4 nm thick layers of Indium, 8 nm thick layers of Zinc and 6 nm thick layers of Gold, respectively

  4. Scaling Principles for Understanding and Exploiting Adhesion

    Science.gov (United States)

    Crosby, Alfred

    A grand challenge in the science of adhesion is the development of a general design paradigm for adhesive materials that can sustain large forces across an interface yet be detached with minimal force upon command. Essential to this challenge is the generality of achieving this performance under a wide set of external conditions and across an extensive range of forces. Nature has provided some guidance through various examples, e.g. geckos, for how to meet this challenge; however, a single solution is not evident upon initial investigation. To help provide insight into nature's ability to scale reversible adhesion and adapt to different external constraints, we have developed a general scaling theory that describes the force capacity of an adhesive interface in the context of biological locomotion. We have demonstrated that this scaling theory can be used to understand the relative performance of a wide range of organisms, including numerous gecko species and insects, as well as an extensive library of synthetic adhesive materials. We will present the development and testing of this scaling theory, and how this understanding has helped guide the development of new composite materials for high capacity adhesives. We will also demonstrate how this scaling theory has led to the development of new strategies for transfer printing and adhesive applications in manufacturing processes. Overall, the developed scaling principles provide a framework for guiding the design of adhesives.

  5. MODELING OF TRACTION SYNCHRONOUS PERMANENT MAGNET MOTOR MODES

    Directory of Open Access Journals (Sweden)

    Y.N. Vas’kovsky

    2013-10-01

    Full Text Available A mathematical model of electromagnetic field for simulating operational modes of traction synchronous motors with permanent magnets intended for electric vehicles is developed. The mathematical model takes into account real-time rotor rotation and allows calculating and analyzing the motor basic running characteristics as time functions.

  6. Physical and electrocardiographic evaluation of horses used for wagon traction

    Directory of Open Access Journals (Sweden)

    M.M. Bomfim

    Full Text Available ABSTRACT The objective of this research was to evaluate the electrocardiogram (ECG of horses used for wagon traction and to compare the results with the parameters obtained from inactive horses or horses submitted to a training routine. Fifty-six 3-15-year-old healthy horses (22 females and 34 males were divided into three groups: control (without a work routine; N=21, wagon traction (N=25 and athlete (N=10 and submitted to physical examination and ECG (at rest. The rhythm, heart rate (HR, amplitude and duration of ECG waveforms and intervals were obtained from the frontal plane and base-apex leads. Heart score (HS was calculated using the arithmetic mean of QRS duration in LI, LII and LIII. Measurements of ECG waves were smaller in control group, in comparison with wagon traction and athlete groups, suggesting that exercise can change ECG. Similar results were observed in the wagon traction and athlete groups, but the electrophysiological adjustments to exercise were not the same for these groups.

  7. LOADING OF MECHANICAL TRANSMISSION OF TROLLEYBUS TRACTION DRIVING GEAR

    Directory of Open Access Journals (Sweden)

    A. I. Safonov

    2009-01-01

    Full Text Available The paper analyzes factors that determine dynamic loads of mechanical transmission of trolleybus traction driving gear. The paper proposes a methodology for determination of calculative moments of loading transmission elements. Results of the research are analyzed and recommendations on  dynamic reduction of trolleybus transmission are given in the paper. 

  8. Traction control of an electric formula student racing car

    NARCIS (Netherlands)

    Loof, J.W.; Besselink, I.J.M.; Nijmeijer, H.

    2014-01-01

    This article describes the design of a traction control system in an electric Formula Student vehicle. In many race applications the accelerator pedal is difficult to control for an in-experienced driver, especially in the case of electric vehicles, where a large torque is available from standstill.

  9. COMPROMISE, OPTIMAL AND TRACTIONAL ACCOUNTS ON PARETO SET

    Directory of Open Access Journals (Sweden)

    V. V. Lahuta

    2010-11-01

    Full Text Available The problem of optimum traction calculations is considered as a problem about optimum distribution of a resource. The dynamic programming solution is based on a step-by-step calculation of set of points of Pareto-optimum values of a criterion function (energy expenses and a resource (time.

  10. Development of low AC loss windings for superconducting traction transformer

    International Nuclear Information System (INIS)

    Kamijo, H; Hata, H; Fukumoto, Y; Tomioka, A; Bohno, T; Yamada, H; Ayai, N; Yamasaki, K; Kato, T; Iwakuma, M; Funaki, K

    2010-01-01

    We have been developing a light weight and high efficiency superconducting traction transformer for railway rolling stock. We designed and fabricated a prototype superconducting traction transformer of a floor-mount type for Shinkansen rolling stock in 2004. We performed the type-test, the system-test, and the vibration-test. Consequently, we could verify that the transformer satisfied the requirement almost exactly as initially planned. However, there have been raised some problems to be solved to put superconducting traction transformer into practical use such that AC loss of the superconducting tape must be lower and the capacity of the refrigerator must be larger. Especially it is the most important to reduce the AC loss of superconducting windings for lightweight and high efficiency. The AC loss must be reduced near the theoretical value of superconducting tape with multifilament. In this study, we fabricated and evaluated the Bi2223 tapes as introduced various measures to reduce the AC loss. We confirmed that the AC loss of the narrow type of Bi2223 tapes with twist of filaments is lower, and we fabricated windings of this tape for use in superconducting traction transformer.

  11. Quality electricity lines of external power systems electric traction DC

    Directory of Open Access Journals (Sweden)

    A.V. Petrov

    2012-08-01

    Full Text Available The results of studies that compare and analyze the numerical values of some key indicators quality electricity in the lines of the external power supply system the electric traction DC. As a supplement are additional and fundamental values of energy losses in them.

  12. THE DYNAMICS AND TRACTION ENERGY METRICS LOCOMOTIVE VL40

    Directory of Open Access Journals (Sweden)

    S. V. Pylypenko

    2008-03-01

    Full Text Available In the article the results of dynamic running and traction-energy tests of the electric locomotive VL40U are presented. In accordance with the test results a conclusion about the suitability of electric locomotive of such a type for operation with trains containing up to 15 passenger coaches inclusive is made.

  13. Apicotomy as Treatment for Failure of Orthodontic Traction

    Directory of Open Access Journals (Sweden)

    Leandro Berni Osório

    2013-01-01

    Full Text Available Objective. The purpose of this study was to present a case report that demonstrated primary failure in a tooth traction that was subsequently treated with apicotomy technique. Case Report. A 10-year-old girl had an impacted upper right canine with increased pericoronal space, which was apparent on a radiographic image. The right maxillary sinus showed an opacity suggesting sinusitis. The presumptive diagnosis was dentigerous cyst associated with maxillary sinus infection. The plan for treatment included treatment of the sinus infection and cystic lesion and orthodontic traction of the canine after surgical exposure and bonding of an orthodontic appliance. The surgical procedure, canine position, root dilaceration, and probably apical ankylosis acted in the primary failure of the orthodontic traction. Surgical apical cut of the displaced teeth was performed, and tooth position in the dental arch was possible, with a positive response to the pulp vitality test. Conclusion. Apicotomy is an effective technique to treat severe canine displacement and primary orthodontic traction failure of palatally displaced canines.

  14. Adhesion mechanism of a gecko-inspired oblique structure with an adhesive tip for asymmetric detachment

    International Nuclear Information System (INIS)

    Sekiguchi, Yu; Sato, Chiaki; Takahashi, Kunio

    2015-01-01

    An adhesion model of an oblique structure with an adhesive tip is proposed by considering a limiting stress for adhesion to describe the detachment mechanism of gecko foot hairs. When a force is applied to the root of the oblique structure, normal and shear stresses are generated at contact and the adhesive tip is detached from the surface when reaching the limiting stress. An adhesion criterion that considers both the normal and shear stresses is introduced, and the asymmetric detachment of the oblique structure is theoretically investigated. In addition, oblique beam array structures are manufactured, and an inclination effect of the structure on the asymmetric detachment is experimentally verified. (paper)

  15. Design and fabrication of polymer based dry adhesives inspired by the gecko adhesive system

    Science.gov (United States)

    Jin, Kejia

    There has been significant interest in developing dry adhesives mimicking the gecko adhesive system, which offers several advantages compared to conventional pressure sensitive adhesives. Specifically, gecko adhesive pads have anisotropic adhesion properties: the adhesive pads (spatulae) stick strongly when sheared in one direction but are non-adherent when sheared in the opposite direction. This anisotropy property is attributed to the complex topography of the array of fine tilted and curved columnar structures (setae) that bear the spatulae. In this thesis, easy, scalable methods, relying on conventional and unconventional techniques are presented to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provide anisotropic adhesion properties. In the first part of the study, the anisotropic adhesion and friction properties of samples with various tilt angles to test the validity of a nanoscale tape-peeling model of spatular function are measured. Consistent with the Peel Zone model, samples with lower tilt angles yielded larger adhesion forces. Contact mechanics of the synthetic array were highly anisotropic, consistent with the frictional adhesion model and gecko-like. Based on the original design, a new design of gecko-like dry adhesives was developed which showed superior tribological properties and furthermore showed anisotropic adhesive properties without the need for tilt in the structures. These adhesives can be used to reversibly suspend weights from vertical surfaces (e.g., walls) and, for the first time to our knowledge, horizontal surfaces (e.g., ceilings) by simultaneously and judiciously activating anisotropic friction and adhesion forces. Furthermore, adhesion properties between artificial gecko-inspired dry adhesives and rough substrates with varying roughness are studied. The results suggest that both adhesion and friction forces on a rough substrate depends significantly on the

  16. Evaluation of force degradation characteristics of orthodontic latex elastics in vitro and in vivo.

    Science.gov (United States)

    Wang, Tong; Zhou, Gang; Tan, Xianfeng; Dong, Yaojun

    2007-07-01

    To evaluate the characteristics of force degradation of latex elastics in clinical applications and in vitro studies. Samples of 3/16-inch latex elastics were investigated, and 12 students between the ages of 12 and 15 years were selected for the intermaxillary and intramaxillary tractions. The elastics in the control groups were set in artificial saliva and dry room conditions and were stretched 20 mm. The repeated-measure two-way analysis of variance and nonlinear regression analysis were used to identify statistical significance. Overall, there were statistically significant differences between the different methods and observation intervals. At 24- and 48-hour time intervals, the force decreased during in vivo testing and in artificial saliva (P .05). In intermaxillary traction the percentage of initial force remaining after 48 hours was 61%. In intramaxillary traction and in artificial saliva the percentage of initial force remaining was 71%, and in room conditions 86% of initial force remained. Force degradation of latex elastics was different according to their environmental conditions. There was significantly more force degradation in intermaxillary traction than in intramaxillary traction. The dry room condition caused the least force loss. There were some differences among groups in the different times to start wearing elastics in intermaxillary traction but no significant differences in intramaxillary traction.

  17. Influences of Traction Load Shock on Artificial Partial Discharge Faults within Traction Transformer—Experimental Test for Pattern Recognition

    Directory of Open Access Journals (Sweden)

    Shuaibing Li

    2017-10-01

    Full Text Available Partial discharge (PD measurement and its pattern recognition are vital to fault diagnosis of transformers, especially to those traction substation transformers undergoing repetitive traction load shocks. This paper presents the primary factors induced by traction load shocks including high total harmonics distortion (THD, transient voltage impulse and high-temperature rise, and their effects on the feature parameters of PD. Experimental tests are conducted on six artificial PD models with these factors introduced one by one. Results reveal that the maximum PD quantity and the PD repetitive rate are favorable to be enlarged when the oil temperature exceeds 80 °C or the THD is higher than 16% with certain orders of harmonic. The decline in PD inception voltage can mainly be attributed to the transient voltage impulse. The variation in central frequency of the fast Fourier transformation (FFT spectra transformed from ultra-high frequency signals can mainly be attributed to high THD, especially when it exceeds 20%. The temperature rise has no significant influence on the FFT spectra; the transient voltage impulse, however, can result in a central frequency shift of the floating particle discharge. With the rapid development of high-speed railways, the study presented in this paper will be helpful for field PD detection and recognition of traction substation transformers in the future.

  18. Fibrillar Adhesive for Climbing Robots

    Science.gov (United States)

    Pamess, Aaron; White, Victor E.

    2013-01-01

    A climbing robot needs to use its adhesive patches over and over again as it scales a slope. Replacing the adhesive at each step is generally impractical. If the adhesive or attachment mechanism cannot be used repeatedly, then the robot must carry an extra load of this adhesive to apply a fresh layer with each move. Common failure modes include tearing, contamination by dirt, plastic deformation of fibers, and damage from loading/ unloading. A gecko-like fibrillar adhesive has been developed that has been shown useful for climbing robots, and may later prove useful for grasping, anchoring, and medical applications. The material consists of a hierarchical fibrillar structure that currently contains two levels, but may be extended to three or four levels in continuing work. The contacting level has tens of thousands of microscopic fibers made from a rubberlike material that bend over and create intimate contact with a surface to achieve maximum van der Waals forces. By maximizing the real area of contact that these fibers make and minimizing the bending energy necessary to achieve that contact, the net amount of adhesion has been improved dramatically.

  19. Research of the multipolar induction traction frequency regulated motor

    Directory of Open Access Journals (Sweden)

    V. Ia. Bespalov

    2014-01-01

    Full Text Available The paper considers the application features of traction induction electric motors in transmissions of vehicles. It shows that one of important stages in their designing is to choose the number of poles. In traction electric drives engines with the raised number of poles without comprehensive assessment of such solution are often applied. The paper investigates dynamic and power characteristics of the multi-polar traction asynchronous engine (TAE designed and made for using in the individual electric drive of heavy-load wheeled cars. The basic functional elements of the model to simulate the electric drive in Matlab environment with the Simulink and SimPower Systems applications in the structure with vector control are described, and the simulation modeling results of its dynamic mechanical characteristics are provided. It is established that because of increased alternating frequency of currents of the multi-polar engine in the range of high speeds there is an excessive decrease in the torque and the requirement for constancy of the target capacity, corresponding to the specified traction characteristic is not fulfilled. It is a consequence of the waveform distortion of engine phase current in the range of high speeds because of incapability of the power source to compensate an increasing EMF of movement as the speed continues to grow.The paper studies the influence of increased current frequencies on the additional losses in the engine. The analysis of electromagnetic field penetration depth in the copper conductor of stator winding at high frequency allowed us to establish a significant skin – effect. The quantitative assessment is given to this phenomenon by results of numerical calculation of electromagnetic field distribution in a stator groove. Significant increase in additional losses in the engine is established, and estimates of flow loss extent because of damping actions of eddy currents in the laminated steel of stator at

  20. Role of flexural stiffness of leukocyte microvilli in adhesion dynamics

    Science.gov (United States)

    Wu, Tai-Hsien; Qi, Dewei

    2018-03-01

    Previous work reported that microvillus deformation has an important influence on dynamics of cell adhesion. However, the existing studies were limited to the extensional deformation of microvilli and did not consider the effects of their bending deformation on cell adhesion. This Rapid Communication investigates the effects of flexural stiffness of microvilli on the rolling process related to adhesion of leukocytes by using a lattice-Boltzmann lattice-spring method (LLM) combined with adhesive dynamics (AD) simulations. The simulation results reveal that the flexural stiffness of microvilli and their bending deformation have a profound effect on rolling velocity and adhesive forces. As the flexural stiffness of the microvilli decreases, their bending angles increase, resulting in an increase in the number of receptor-ligand bonds and adhesive bonding force and a decrease in the rolling velocity of leukocytes. The effects of flexural stiffness on deformation and adhesion represent crucial factors involved in cell adhesion.

  1. Research on a New Bilateral Self-locking Mechanism for an Inchworm Micro In-pipe Robot with Large Traction

    Directory of Open Access Journals (Sweden)

    Junhong Yang

    2014-10-01

    Full Text Available In this paper, we present an innovative bilaterally-controllable self-locking mechanism that can be applied to the micro in-pipe robot. The background and state of the art of the inchworm micro in-pipe robot is briefly described in the very beginning of the paper, where the main factors that influence the traction ability are also discussed. Afterwards, the micro in-pipe robots’ propulsion principle based on a unidirectional self-locking mechanism is discussed. Then, several kinds of self-locking mechanisms are compared, and a new bilaterally-controllable self-locking mechanism is proposed. By implementing the self-locking mechanism, the robot's tractive force is no longer restricted by the friction force, and both two-way motion and position locking for the robot can be achieved. Finally, the traction experiment is conducted using a prototype robot with the new bilaterally-controllable self-locking mechanism. Test results show that this new self-locking mechanism can adapt itself to a diameter of >17~>20 mm and has a blocking force up to 25N, and the maximum tractive force of the in-pipe robot based on such a locking mechanism is 12N under the maximum velocity of 10mm/s.

  2. Design methodology for nano-engineered surfaces to control adhesion: Application to the anti-adhesion of particles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taekyung [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); School of Mechanical Engineering, Yonsei University, Seoul 03722 (Korea, Republic of); Min, Cheongwan [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); Jung, Myungki; Lee, Jinhyung; Park, Changsu [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); School of Mechanical Engineering, Yonsei University, Seoul 03722 (Korea, Republic of); Kang, Shinill, E-mail: snlkang@yonsei.ac.kr [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); School of Mechanical Engineering, Yonsei University, Seoul 03722 (Korea, Republic of)

    2016-12-15

    Highlights: • A design method using the Derjaguin approximation with FEA for low-adhesion surface. • Fabrication of nanostructures with small adhesion forces by presented design method. • Characterization of adhesion force via AFM FD-curve with modified atypical tips. • Verification of low-adhesion of designed surfaces using centrifugal detachment tests. • Investigation of interdependence of hydrophobicity and anti-adhesion force. - Abstract: With increasing demand for means of controlling surface adhesion in various applications, including the semiconductor industry, optics, micro/nanoelectromechanical systems, and the medical industry, nano-engineered surfaces have attracted much attention. This study suggests a design methodology for nanostructures using the Derjaguin approximation in conjunction with finite element analysis for the control of adhesion forces. The suggested design methodology was applied for designing a nano-engineered surface with low-adhesion properties. To verify this, rectangular and sinusoidal nanostructures were fabricated and analyzed using force-distance curve measurements using atomic force microscopy and centrifugal detachment testing. For force-distance curve measurements, modified cantilevers with tips formed with atypical particles were used. Subsequently, centrifugal detachment tests were also conducted. The surface wettability of rectangular and sinusoidal nanostructures was measured and compared with the measured adhesion force and the number of particles remaining after centrifugal detachment tests.

  3. Posture manipulation for rescue activity via small traction robots

    International Nuclear Information System (INIS)

    Iwano, Yuki; Osuka, Koichi; Amano, Hisanori

    2006-01-01

    We discuss a conceptual design of rescue robots against nuclear-power plant accidents. We claim that the rescue robots in nuclear-power plants should have the following properties. (1) The size is small. (2) The structure is simple. (3) The number of the robots is large. This paper studies the rescue robots to rescue people in an area polluted with radioactive leakage in nuclear power institutions. In particular, we propose a rescue system which consists of a group of small mobile robots. First, small traction robots set the posture of the fainted victims to carry easily, and carry them to the safety space with the mobile robots for the stretcher composition. In this paper, we describe the produced small traction robots. And, we confirm that the robots can manipulate a 40 kg dummy doll's posture. We also examine the optimal number of robots from a perspective of working efficiency in the assumption spot. (author)

  4. Fabrication of Superconducting Traction Transformer for Railway Rolling Stock

    International Nuclear Information System (INIS)

    Kamijo, H; Hata, H; Fujimoto, H; Inoue, A; Nagashima, K; Ikeda, K; Yamada, H; Sanuki, Y; Tomioka, A; Uwamori, K; Yoshida, S; Iwakuma, M; Funaki, K

    2006-01-01

    We designed a floor type single-phase 4 MVA superconducting traction transformer for Shinkansen rolling stock. In this study, we fabricated a prototype superconducting traction transformer based on this design. This transformer of the core-type design has a primary winding, four secondary windings and a tertiary winding. The windings are wound by Bi2223 superconducting tapes and cooled by subcooled liquid nitrogen. The core is kept at room temperature. The cryostat is made of GFRP with two holes to pass core legs through. The outer dimensions are about 1.2m x 0.7m x 1.9m excluding the compressor. Its weight is 1.71t excluding that of refrigerator and compressor. The transformer was tested according to Japanese Industrial Standards (JIS)-E5007. We confirmed that the performance of transformer has been achieved almost exactly as planned. The rated capacity is equivalent to 3.5MVA in the superconducting state

  5. Evidence for van der Waals adhesion in gecko setae

    OpenAIRE

    Autumn, Kellar; Sitti, Metin; Liang, Yiching A.; Peattie, Anne M.; Hansen, Wendy R.; Sponberg, Simon; Kenny, Thomas W.; Fearing, Ronald; Israelachvili, Jacob N.; Full, Robert J.

    2002-01-01

    Geckos have evolved one of the most versatile and effective adhesives known. The mechanism of dry adhesion in the millions of setae on the toes of geckos has been the focus of scientific study for over a century. We provide the first direct experimental evidence for dry adhesion of gecko setae by van der Waals forces, and reject the use of mechanisms relying on high surface polarity, including capillary adhesion. The toes of live Tokay geckos were highly hydrophobic, and adhered equally well ...

  6. Creation of electromechanical device for electric vehicle traction

    Directory of Open Access Journals (Sweden)

    Денис Юрьевич Зубенко

    2016-10-01

    Full Text Available The problems of creation of electromechanical device for electric vehicle traction are considered in the article. The aim of creation this design are the replacement of the internal combustion engine on electromechanical device. For this electromechanical device are constructed model, which describe processes that occur in the electric drive of electromechanical device. Characteristics of the main modes of motion were recorded. The introduction of electromechanical device will reduce the level of emissions and reduce noise in the cities

  7. Modern Solutions for Automation of Electrical Traction Power Supply Systems

    Directory of Open Access Journals (Sweden)

    Ana Mihaela Andreica

    2011-09-01

    Full Text Available This paper presents modern solutions for the automation of the electrical traction power supply system used in urban public transport (trams, trolleybuses and subway trains. The monitoring and control of this process uses SCADA distributed architectures, grouped around a central point (dispatcher who controls all field sensors, transmitters and actuators using programmable logical controllers. The presented applications refer to the Bucharest electrical transport infrastructure.

  8. REACTIVE POWER DEVICES IN SYSTEMS OF ELECTRIC TRACTION

    Directory of Open Access Journals (Sweden)

    M. O. Kostin

    2010-04-01

    Full Text Available A comparative characteristic of different concepts and expressions for determination of reactive power in the circuits with non-sinusoidal electric values has been given. For the first Ukrainian electric locomotives of DE1 type with the system of DC electric traction, the values of reactive power after Budeany, Fryze, and also the differential, integral and generalized reactive powers have been determined. Some measures on reducing its consumption by the DC electric rolling stock have been suggested.

  9. Road dust from pavement wear and traction sanding

    Energy Technology Data Exchange (ETDEWEB)

    Kupiainen, K.

    2007-07-01

    Vehicles affect the concentrations of ambient airborne particles through exhaust emissions, but particles are also formed in the mechanical processes in the tire-road interface, brakes, and engine. Particles deposited on or in the vicinity of the road may be re-entrained, or resuspended, into air through vehicle-induced turbulence and shearing stress of the tires. A commonly used term for these particles is 'road dust'. The processes affecting road dust emissions are complex and currently not well known. Road dust has been acknowledged as a dominant source of PM10 especially during spring in the sub-arctic urban areas, e.g. in Scandinavia, Finland, North America and Japan. The high proportion of road dust in sub-arctic regions of the world has been linked to the snowy winter conditions that make it necessary to use traction control methods. Traction control methods include dispersion of traction sand, melting of ice with brine solutions, and equipping the tires with either metal studs (studded winter tires), snow chains, or special tire design (friction tires). Several of these methods enhance the formation of mineral particles from pavement wear and/or from traction sand that accumulate in the road environment during winter. When snow and ice melt and surfaces dry out, traffic-induced turbulence makes some of the particles airborne. A general aim of this study was to study processes and factors underlying and affecting the formation and emissions of road dust from paved road surfaces. Special emphasis was placed on studying particle formation and sources during tire road interaction, especially when different applications of traction control, namely traction sanding and/or winter tires were in use. Respirable particles with aerodynamic diameter below 10 micrometers (PM10) have been the main concern, but other size ranges and particle size distributions were also studied. The following specific research questions were addressed: (i) How do traction

  10. Probing bacterial adhesion at the single-cell level

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Müller, Torsten; Meyer, Rikke Louise

    be considered. We have developed a simple and versatile method to make single-cell bacterial probes for measuring single cell adhesion by force spectroscopy using atomic force microscopy (AFM). A single-cell probe was readily made by picking up a bacterial cell from a glass surface by approaching a tipless AFM...... cantilever coated with the commercial cell adhesive CellTakTM. We applied the method to study adhesion of living cells to abiotic surfaces at the single-cell level. Immobilisation of single bacterial cells to the cantilever was stable for several hours, and viability was confirmed by Live/Dead staining...... on the adhesion force, we explored the bond formation and adhesive strength of four different bacterial strains towards three abiotic substrates with variable hydrophobicity and surface roughness. The adhesion force and final rupture length were dependent on bacterial strains, surfaces properties, and time...

  11. Insights into adhesion of abalone: A mechanical approach.

    Science.gov (United States)

    Li, Jing; Zhang, Yun; Liu, Sai; Liu, Jianlin

    2018-01-01

    Many living creatures possess extremely strong capability of adhesion, which has aroused great attention of many scientists and engineers. Based on the self-developed equipment, we measured the normal and shear adhesion strength of the abalone underwater and out of water on different contact surfaces. It is found that the adhesion force of the abalone can amount to 200 or 300 times its body weight. The effects of wettability and roughness of the surface, and the frictional coefficient of mucus on the adhesion strength have been discussed. The theoretical calculation manifests that the normal adhesion force mainly stems from the suction pressure, van der Waals force and capillary force of the pedal, and their limit values are given. These findings may provide some inspirations to engineer new-typed materials, micro-devices, adhesives and medicine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Adhesion experiments using an AFM-Parameters of influence

    NARCIS (Netherlands)

    Dos Santos Ferreira, O.; Gelinck, E.R.M.; Graaf, D. de; Fischer, H.

    2010-01-01

    Adhesion measurements were performed by AFM (Atomic Force Microscopy). It was shown that many parameters need to be controlled in order to provide reproducible and quantitative results. Adhesion forces were shown to depend on combination of materials characteristics and testing geometry as well as

  13. Adhesion of Spores of Bacillus thuringiensis on a Planar Surface

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Lee, Ida [University of Tennessee, Knoxville (UTK); Joy, David Charles [ORNL; Palumbo, Anthony Vito [ORNL; Tsouris, Costas [ORNL

    2010-01-01

    Adhesion of spores of Bacillus thuringiensis (Bt) and spherical silica particles on surfaces was experimentally and theoretically investigated in this study. Topography analysis via atomic force microscopy (AFM) and electron microscopy indicates that Bt spores are rod shaped, {approx}1.3 {mu}m in length and {approx}0.8 {mu}m in diameter. The adhesion force of Bt spores and silica particles on gold-coated glass was measured at various relative humidity (RH) levels by AFM. It was expected that the adhesion force would vary with RH because the individual force components contributing to the adhesion force depend on RH. The adhesion force between a particle and a planar surface in atmospheric environments was modeled as the contribution of three major force components: capillary, van der Waals, and electrostatic interaction forces. Adhesion force measurements for Bt spore (silica particle) and the gold surface system were comparable with calculations. Modeling results show that there is a critical RH value, which depends on the hydrophobicity of the materials involved, below which the water meniscus does not form and the contribution of the capillary force is zero. As RH increases, the van der Waals force decreases while the capillary force increases to a maximum value.

  14. Sustainability Aspects of Energy Conversion in Modern High-Speed Trains with Traction Induction Motors

    Directory of Open Access Journals (Sweden)

    Marc A. Rosen

    2015-03-01

    Full Text Available Some aspects are illustrated of energy conversion processes during the operation of electric railway vehicles with traction induction motors, in order to support transport systems’ sustainability. Increasing efforts are being expended to enhance the sustainability of transportation technologies and systems. Since electric drive systems are used with variable voltage variable frequency (VVVF inverters and traction induction motors, these machines with appropriate controls can realize both traction and electric braking regimes for electric traction vehicles. In line with this idea, this paper addresses the operation sustainability of electric railway vehicles highlighting the chain of interactions among the main electric equipment on an electrically driven railway system supplied from an a.c. contact line: The contact line-side converter, the machine-side converter and the traction induction motor. The paper supports the findings that electric traction drive systems using induction motors fed by network-side converters and VVVF inverters enhance the sustainable operation of railway trains.

  15. Adhesion in microelectronics

    CERN Document Server

    Mittal, K L

    2014-01-01

    This comprehensive book will provide both fundamental and applied aspects of adhesion pertaining to microelectronics in a single and easily accessible source. Among the topics to be covered include; Various theories or mechanisms of adhesionSurface (physical or chemical) characterization of materials as it pertains to adhesionSurface cleaning as it pertains to adhesionWays to improve adhesionUnraveling of interfacial interactions using an array of pertinent techniquesCharacterization of interfaces / interphasesPolymer-polymer adhesionMetal-polymer adhesion  (metallized polymers)Polymer adhesi

  16. Interfacial force measurements using atomic force microscopy

    NARCIS (Netherlands)

    Chu, L.

    2018-01-01

    Atomic Force Microscopy (AFM) can not only image the topography of surfaces at atomic resolution, but can also measure accurately the different interaction forces, like repulsive, adhesive and lateral existing between an AFM tip and the sample surface. Based on AFM, various extended techniques have

  17. Orthodontic traction of a transmigrated mandibular canine using mini-implant: a case report and review.

    Science.gov (United States)

    Plaza, Sonia Patricia

    2016-12-01

    The patient in this case is an 11-year-old girl, whose mandibular left canine was transmigrated. The traction to the arch was assisted by using a temporary skeletal anchorage device. After 5 months of poor response to traction, the biomechanics were re-adjusted, obtaining effective traction in to the arch in 12 months. After this period, the treatment was completed with fixed orthodontic appliances.

  18. Distributed active traction control system applied to the RoboCup middle size league

    OpenAIRE

    Almeida, José; Dias, André; Sequeira, João; Martins, Alfredo; Silva, Eduardo

    2013-01-01

    This work addresses the problem of traction control in mobile wheeled robots in the particular case of the RoboCup Middle Size League (MSL). The slip control problem is formulated using simple friction models for ISePorto Team robots with a differential wheel configuration. Traction was also characterized experimentally in the MSL scenario for relevant game events. This work proposes a hierarchical traction control architecture which relies in local slip detection and con...

  19. Reflections about Adhesive Systems

    OpenAIRE

    de Freitas Borges, Marciano; Diesel, Pâmela Gutheil; Corrêa, Fernanda Gomez; Bernardi, Eledana; Fernandes Montagner, Anelise; Skupien, Jovito Adiel; Susin, Alexandre Henrique

    2010-01-01

    The adhesive systems are responsible for an efficient union between teeth and resin, resulting in a longevity restoration. They are organic molecules di or multifunctional that contain reactive groups that interact with dentin and with the resin monomer of composite resin. The adhesive systems are characterized by wet adhesion, which is a result of presence of hidrophylics radicals in their compositions, to promote a better bond and the best properties of the adhesion. Adhesive systems may us...

  20. Evidence for van der Waals adhesion in gecko setae.

    Science.gov (United States)

    Autumn, Kellar; Sitti, Metin; Liang, Yiching A; Peattie, Anne M; Hansen, Wendy R; Sponberg, Simon; Kenny, Thomas W; Fearing, Ronald; Israelachvili, Jacob N; Full, Robert J

    2002-09-17

    Geckos have evolved one of the most versatile and effective adhesives known. The mechanism of dry adhesion in the millions of setae on the toes of geckos has been the focus of scientific study for over a century. We provide the first direct experimental evidence for dry adhesion of gecko setae by van der Waals forces, and reject the use of mechanisms relying on high surface polarity, including capillary adhesion. The toes of live Tokay geckos were highly hydrophobic, and adhered equally well to strongly hydrophobic and strongly hydrophilic, polarizable surfaces. Adhesion of a single isolated gecko seta was equally effective on the hydrophobic and hydrophilic surfaces of a microelectro-mechanical systems force sensor. A van der Waals mechanism implies that the remarkable adhesive properties of gecko setae are merely a result of the size and shape of the tips, and are not strongly affected by surface chemistry. Theory predicts greater adhesive forces simply from subdividing setae to increase surface density, and suggests a possible design principle underlying the repeated, convergent evolution of dry adhesive microstructures in gecko, anoles, skinks, and insects. Estimates using a standard adhesion model and our measured forces come remarkably close to predicting the tip size of Tokay gecko seta. We verified the dependence on size and not surface type by using physical models of setal tips nanofabricated from two different materials. Both artificial setal tips stuck as predicted and provide a path to manufacturing the first dry, adhesive microstructures.

  1. Adhesive performance of precoated brackets after expiration.

    Science.gov (United States)

    Cloud, Cayce C; Trojan, Terry M; Suliman, Sam N; Tantbirojn, Daranee; Versluis, Antheunis

    2016-03-01

    To evaluate adhesive performance in terms of debonding forces of precoated metal and ceramic brackets 4 years after expiration. Buccal and lingual surfaces of embedded extracted maxillary premolars were etched with 34% Tooth Conditioner Gel (Dentsply Caulk, Milford, Del), rinsed, and dried. Transbond MIP (3M Unitek, Monrovia, Calif) was applied prior to placing adhesive precoated brackets (APC II Victory stainless steel and APC Plus Clarity ceramic brackets, 3M Unitek). The preexpiration brackets had 29-35 months before, and the postexpiration brackets were 45-52 months past, their expiration dates. Sample size was 17-21 per group. Debonding forces were determined by subjecting the bonded brackets to a shear force in a universal testing machine. Debonding forces were compared using two-way ANOVA. Debonded surfaces were examined under a stereomicroscope to determine failure modes, which were compared using the chi-square test. No statistically significant difference was found in debonding forces (P  =  .8581) or failure modes (P  =  .4538) between expired and unexpired brackets. Metal brackets required statistically significantly higher debonding forces than did ceramic brackets (P  =  .0001). For both expired and unexpired brackets, failure modes were mostly cohesive in the adhesive layer for ceramic brackets, and mixed between adhesive and cohesive failure in the adhesive layer for metal brackets. Adhesive precoated brackets did not have any reduction in enamel-adhesion properties up to 4 years after their expiration date. Extended shelf life testing for precoated dental brackets may be worth considering.

  2. Do uniform tangential interfacial stresses enhance adhesion?

    Science.gov (United States)

    Menga, Nicola; Carbone, Giuseppe; Dini, Daniele

    2018-03-01

    We present theoretical arguments, based on linear elasticity and thermodynamics, to show that interfacial tangential stresses in sliding adhesive soft contacts may lead to a significant increase of the effective energy of adhesion. A sizable expansion of the contact area is predicted in conditions corresponding to such scenario. These results are easily explained and are valid under the assumptions that: (i) sliding at the interface does not lead to any loss of adhesive interaction and (ii) spatial fluctuations of frictional stresses can be considered negligible. Our results are seemingly supported by existing experiments, and show that frictional stresses may lead to an increase of the effective energy of adhesion depending on which conditions are established at the interface of contacting bodies in the presence of adhesive forces.

  3. Frequency of vitreo macular traction in diabetic macular edema on optical coherence tomography

    International Nuclear Information System (INIS)

    Fatima, N.; Islam, Q.U.; Shafique, M.

    2017-01-01

    To determine the frequency of vitreo macular traction (VMT) in patients of diabetic macular edema (DME) as detected on spectral domain optical coherence tomography (SD-OCT). Study Design: Cross-sectional study. Place and Duration of Study: Armed Forces Institute of Ophthalmology (AFIO) Rawalpindi, from May 2013 to Jan 2014. Patients and Methods: Diabetic patients of less than 18 years of age with DME and central macular thickness of more than 250 micrometers (micro m) were included. The patients with idiopathic VMT, history of vitreoretinal surgery, and history of other retinal vascular diseases were excluded from the study. Dilated fundus was done in each patient using 90 D lens on a slit lamp biomicroscope and patients with diabetic retinopathy changes and DME were subjected to OCT examination using Topcon 3-D OCT 1000 (Topcon Corporation). Record of each patient including demographic data, ocular findings and OCT data were endorsed on a pre-devised proforma. Results: Seventy one eyes of 68 patients were included, 36 (50.7 percent) were males and 35 (49.29 percent) were females. Mean age was 53.17 +- 8.79 years. Mean central macular thickness (CMT) was 361.8 +- 109 mu m. VMT was detected in 17 (23.9 percent) eyes. Amongst these, 2(12.5 percent) eyes had vitreofoveal traction, epiretinal membrane was found in 4 (25 percent) eyes and 11(62.5 percent) eyes had extra foveal VMT. Conclusion: Detection of VMT in about a quarter of cases reflects that OCT is a viable tool for early detection of vitreomacular interface abnormalities. (author)

  4. Model-based efficiency evaluation of combine harvester traction drives

    Directory of Open Access Journals (Sweden)

    Steffen Häberle

    2015-08-01

    Full Text Available As part of the research the drive train of the combine harvesters is investigated in detail. The focus on load and power distribution, energy consumption and usage distribution are explicitly explored on two test machines. Based on the lessons learned during field operations, model-based studies of energy saving potential in the traction train of combine harvesters can now be quantified. Beyond that the virtual machine trial provides an opportunity to compare innovative drivetrain architectures and control solutions under reproducible conditions. As a result, an evaluation method is presented and generically used to draw comparisons under local representative operating conditions.

  5. FreedomCAR Advanced Traction Drive Motor Development Phase I

    Energy Technology Data Exchange (ETDEWEB)

    Ley, Josh (UQM Technologies, Inc.); Lutz, Jon (UQM Technologies, Inc.)

    2006-09-01

    The overall objective of this program is to design and develop an advanced traction motor that will meet the FreedomCAR and Vehicle Technologies (FCVT) 2010 goals and the traction motor technical targets. The motor specifications are given in Section 1.3. Other goals of the program include providing a cost study to ensure the motor can be developed within the cost targets needed for the automotive industry. The program has focused on using materials that are both high performance and low costs such that the performance can be met and cost targets are achieved. In addition, the motor technologies and machine design features must be compatible with high volume manufacturing and able to provide high reliability, efficiency, and ruggedness while simultaneously reducing weight and volume. Weight and volume reduction will become a major factor in reducing cost, material cost being the most significant part of manufacturing cost at high volume. Many motor technology categories have been considered in the past and present for traction drive applications, including: brushed direct current (DC), PM (PM) brushless dc (BLDC), alternating current (AC) induction, switched reluctance and synchronous reluctance machines. Of these machine technologies, PM BLDC has consistently demonstrated an advantage in terms of power density and efficiency. As rare earth magnet cost has declined, total cost may also be reduced over the other technologies. Of the many different configurations of PM BLDC machines, those which incorporate power production utilizing both magnetic torque as well as reluctance torque appear to have the most promise for traction applications. There are many different PM BLDC machine configurations which employ both of these torque producing mechanisms; however, most would fall into one of two categories--some use weaker magnets and rely more heavily on reluctance torque (reluctance-dominant PM machines), others use strong PMs and supplement with reluctance torque

  6. Sliding Adhesion Dynamics of Isolated Gecko Setal Arrays

    Science.gov (United States)

    Sponberg, Simon; Autumn, Kellar

    2003-03-01

    The tokay gecko (Gekko gecko) can adhere to nearly any surface through van der Waals interactions of the specialized setae (b-keratin "hairs") of its toe pads. Our recent research has suggested that a gecko is substantially overbuilt for static adhesion requiring as little as 0.03of its theoretical adhesive capacity. We performed the first sliding adhesion experiments on this novel biological adhesive to determine its response to dynamic loading. We isolated arrays of setae and constructed a precision controlled Robo-toe to study sliding effects. Our results indicate that, unlike many typical adhesives, gecko setal arrays exhibit an increased frictional force upon sliding (mk > ms) which further increases with velocity, suggesting that perturbation rejection may be an evolutionary design principle underlying the evolution of the gecko adhesive. We compare these dynamic properties with those of other adhesives and explore the impacts of these results on the design of artificial adhesives.

  7. A microfabricated gecko-inspired controllable and reusable dry adhesive

    International Nuclear Information System (INIS)

    Chary, Sathya; Tamelier, John; Turner, Kimberly

    2013-01-01

    Geckos utilize a robust reversible adhesive to repeatedly attach and detach from a variety of vertical and inverted surfaces, using structurally anisotropic micro- and nano-scale fibrillar structures. These fibers, when suitably articulated, are able to control the real area of contact and thereby generate high-to-low van der Waals forces. Key characteristics of the natural system include highly anisotropic adhesion and shear forces for controllable attachment, a high adhesion to initial preload force ratio (μ′) of 8–16, lack of inter-fiber self-adhesion, and operation over more than 30 000 cycles without loss of adhesion performance. A highly reusable synthetic adhesive has been developed using tilted polydimethylsiloxane (PDMS) half-cylinder micron-scale fibers, retaining up to 77% of the initial value over 10 000 repeated test cycles against a flat glass puck. In comparison with other gecko-inspired adhesives tested over 10 000 cycles or more thus far, this paper reports the highest value of μ′, along with a large shear force of ∼78 kPa, approaching the 88–226 kPa range of gecko toes. The anisotropic adhesion forces are close to theoretical estimates from the Kendall peel model, quantitatively showing how lateral shearing articulation in a manner similar to the gecko may be used to obtain adhesion anisotropy with synthetic fibers using a combination of tilt angle and anisotropic fiber geometry. (paper)

  8. A microfabricated gecko-inspired controllable and reusable dry adhesive

    Science.gov (United States)

    Chary, Sathya; Tamelier, John; Turner, Kimberly

    2013-02-01

    Geckos utilize a robust reversible adhesive to repeatedly attach and detach from a variety of vertical and inverted surfaces, using structurally anisotropic micro- and nano-scale fibrillar structures. These fibers, when suitably articulated, are able to control the real area of contact and thereby generate high-to-low van der Waals forces. Key characteristics of the natural system include highly anisotropic adhesion and shear forces for controllable attachment, a high adhesion to initial preload force ratio (μ‧) of 8-16, lack of inter-fiber self-adhesion, and operation over more than 30 000 cycles without loss of adhesion performance. A highly reusable synthetic adhesive has been developed using tilted polydimethylsiloxane (PDMS) half-cylinder micron-scale fibers, retaining up to 77% of the initial value over 10 000 repeated test cycles against a flat glass puck. In comparison with other gecko-inspired adhesives tested over 10 000 cycles or more thus far, this paper reports the highest value of μ‧, along with a large shear force of ˜78 kPa, approaching the 88-226 kPa range of gecko toes. The anisotropic adhesion forces are close to theoretical estimates from the Kendall peel model, quantitatively showing how lateral shearing articulation in a manner similar to the gecko may be used to obtain adhesion anisotropy with synthetic fibers using a combination of tilt angle and anisotropic fiber geometry.

  9. Adhesion Between Poly(dimethylsiloxane) Layers

    DEFF Research Database (Denmark)

    Yu, Liyun; Daugaard, Anders Egede; Skov, Anne Ladegaard

    Different adhesion methods of poly(dimethylsiloxane) (PDMS) layers were studied with respect to adhesional force and the resulting rheology of the two-layered PDMS films were investigated. The role of adhesion between PDMS layers on the performances of two-layer structures was studied with peel...... strength test and by SEM pictures. The rheology of the double-layered compared to the monolayer films changed in some cases which indicates that the adhesion process needs to be carefully introduced in order not to alter the final properties....

  10. Regulation of brain tumor dispersal by NKCC1 through a novel role in focal adhesion regulation.

    Directory of Open Access Journals (Sweden)

    Tomas Garzon-Muvdi

    Full Text Available Glioblastoma (GB is a highly invasive and lethal brain tumor due to its universal recurrence. Although it has been suggested that the electroneutral Na(+-K(+-Cl(- cotransporter 1 (NKCC1 can play a role in glioma cell migration, the precise mechanism by which this ion transporter contributes to GB aggressiveness remains poorly understood. Here, we focused on the role of NKCC1 in the invasion of human primary glioma cells in vitro and in vivo. NKCC1 expression levels were significantly higher in GB and anaplastic astrocytoma tissues than in grade II glioma and normal cortex. Pharmacological inhibition and shRNA-mediated knockdown of NKCC1 expression led to decreased cell migration and invasion in vitro and in vivo. Surprisingly, knockdown of NKCC1 in glioma cells resulted in the formation of significantly larger focal adhesions and cell traction forces that were approximately 40% lower than control cells. Epidermal growth factor (EGF, which promotes migration of glioma cells, increased the phosphorylation of NKCC1 through a PI3K-dependant mechanism. This finding is potentially related to WNK kinases. Taken together, our findings suggest that NKCC1 modulates migration of glioma cells by two distinct mechanisms: (1 through the regulation of focal adhesion dynamics and cell contractility and (2 through regulation of cell volume through ion transport. Due to the ubiquitous expression of NKCC1 in mammalian tissues, its regulation by WNK kinases may serve as new therapeutic targets for GB aggressiveness and can be exploited by other highly invasive neoplasms.

  11. MONITORING OF ELECTRICAL ENERGY QUALITY ON THE TRACTION SUBSTATION INPUT

    Directory of Open Access Journals (Sweden)

    O.G. Gryb

    2015-12-01

    Full Text Available For the implementation of measures to maintain the quality of the energy industrial enterprises have to spend a significant material and monetary assets. In this regard, significant is the feasibility study of the allocation of such funds and, primarily, the determination of the economic damage arising from low quality of electricity. The reliability of the electricity metering system, relay protection and automation of modern digital substations depends on the quality of electrical energy. At the present time to improve the reliability of the substation operation it is necessary to monitor indicators of quality of electric energy, allowing you to take organizational and technical solutions for their improvement. Monitoring the power quality at the input traction substation has shown that indicators such as the coefficient of the n-th harmonic component of the voltage does not meet the standards GOST 13109-97. The source of higher harmonics is a voltage Converter used on the locomotive. To eliminate higher harmonics in the supply network for traction substations will need to install power filters. Today, the USB-analyzer of power quality «Digital measurement system of power quality» type of CSICE of accuracy class 0.2. Work energy requires reliable and quality electricity supply to consumers. The new model of balancing energy market are bilateral contracts. The main task of this market, it ensure the stable and reliable operation of the unified energy system of Ukraine, that is, transmission and supply of electricity of appropriate quality.

  12. Control algorithms for single inverter dual induction motor system applied to railway traction; Commande algorithmique d'un systeme mono-onduleur bimachine asynchrone destine a la traction ferroviaire

    Energy Technology Data Exchange (ETDEWEB)

    Pena Eguiluz, R.

    2002-11-15

    The goal of this work concerns the modelling and the behaviour characterisation of a single inverter dual induction motor system applied to a railway traction bogie (BB36000) in order to concept its control. First part of this job is dedicated to the detailed description of overall system. The influence analysis of the internal perturbations (motor parameters variation) and, external perturbations (pantograph detachment, adherence loss, stick-slip) of the system have made considering the field oriented control applied to each motor of the bogie (classical traction structure). vi In a second part, a novel propulsion structure is proposed. It is composed by a single pulse-width modulated two level voltage source inverter. It supplies two parallel connected induction motors, which generate the transmitted traction force to the bogie wheels. The locomotive case represents the common load for the two motors. Several co-operative control strategies (CS) are studied. They are: the mean CS, the double mean CS, the master - slave switched CS and, the mean differential CS. In addition, an appropriated electric modes observer structure for these different controls has studied. These controls have validated applying the perturbations to the models using the solver SABER. This special approach is equivalent to quasi-experimentation, because the mechanical and the electrical system components have modelled using MAST language and, the sample control has created by a C code programme in the SABER environment. Third part is dedicated to the mechanical sensor suppression and, its adaptation in the cooperative control strategies. The partial speed reconstruction methods are: the fundamental frequency relation, the mechanical Kalman filter, the variable structure observer and the MRAS. Finally, the hardware system configuration of the experimental realisation is described. (author)

  13. Chapter 9:Wood Adhesion and Adhesives

    Science.gov (United States)

    Charles R. Frihart

    2013-01-01

    The recorded history of bonding wood dates back at least 3000 years to the Egyptians (Skeist and Miron 1990, River 1994a), and adhesive bonding goes back to early mankind (Keimel 2003). Although wood and paper bonding are the largest applications for adhesives, some of the fundamental aspects leading to good bonds are not fully understood. Better understanding of these...

  14. Osteo-odonto-keratoprosthesis (OOKP) and the testing of three different adhesives for bonding bovine teeth with optical poly-(methyl methacrylate) (PMMA) cylinder.

    Science.gov (United States)

    Weisshuhn, K; Berg, I; Tinner, D; Kunz, C; Bornstein, M M; Steineck, M; Hille, K; Goldblum, D

    2014-07-01

    Preparation of the lamina during osteo-odonto-keratoprosthesis (OOKP) design is complex, and its longevity and watertightness important. To date, only acrylic bone cements have been used for bonding the optical cylinder to the tooth dentine. Our aim was to evaluate different dental adhesives for OOKP preparation. Specimens of bovine teeth were produced by preparing 1.5-mm thick dentine slices with holes having a diameter of 3.5 mm. Each group (n=10 per group) was luted with either classic poly-(methyl methacrylate) (PMMA) bone cement, universal resin cement or glass ionomer cement. All specimens underwent force measurement using a uniaxial traction machine. The highest mean force required to break the bond was measured for PMMA bone cement (128.2 N) followed by universal resin cement (127.9 N), with no statistically significant difference. Glass ionomer cement showed significantly lower force resistance (78.1 N). Excellent bonding strength combined with easy application was found for universal resin cement, and thus, it is a potential alternative to acrylic bone cement in OOKP preparation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  15. Changes in dynamics processes of the muscles’ traction under influence of stress-factors

    Directory of Open Access Journals (Sweden)

    D. M. Nozdrenko

    2006-01-01

    Full Text Available Change of fibers’ dynamic parameters of the frog Rana temporaria skeletal muscle m. tibialis traction under influence of modulated stimulation and aluminium chloride solutions was studied. At 10-4,5·10-4 and 10‑3 M·l-1 concentrations of aluminium chloride the nonlinear decrease of the muscle fibers’ traction parameters was observed.

  16. Skull traction for cervical spinal injury in Enugu: A 5‑year ...

    African Journals Online (AJOL)

    Forty‑one had the American Spinal Injury Association (ASIA) Grade A whereas 64 had incomplete cord injury of ASIA Grades B–E. Forty‑eight had Crutchfield traction whereas 57 had Gardner‑Wells traction. At the end of treatment, no patient improved among those with ASIA Grades A and B. All the 12 cases of mortality ...

  17. Introducing the inbed spinal traction kit for use on patients with low ...

    African Journals Online (AJOL)

    BACKGROUND: Low backpain is a common malady in our environment. BODY: The in-bed spinal Traction kit is designed and assembled by the authors for use in treatment of Low Back Pain. The aim is to reduce cost, shorten period of Hospital stay and immobilization encountered when skin Traction Devices are used in ...

  18. The Harmonoise/IMAGINE model for traction noise of powered railway vehicles

    NARCIS (Netherlands)

    Dittrich, M.G.; Zhang, X.

    2006-01-01

    Traction noise is one of the noise sources of powered railway vehicles such as locomotives, electric- and diesel-powered multiple unit trains and high-speed trains. Especially at speeds below 60 km/h and at idling, but also at acceleration conditions for a wide range of speeds, traction noise can be

  19. Impedance-Based Harmonic Instability Assessment in Multiple Electric Trains and Traction Network Interaction System

    DEFF Research Database (Denmark)

    Tao, Haidong; Hu, Haitao; Wang, Xiongfei

    2018-01-01

    This paper presents an impedance-based method to systematically investigate the interaction between multi-train and traction networks, focusing on evaluating the harmonic instability problems. Firstly, the interaction mechanism of multi-train and the traction network is represented as a feedback ...

  20. THz Properties of Adhesives

    Science.gov (United States)

    Stübling, E.; Gomell, L.; Sommer, S.; Winkel, A.; Kahlmeyer, M.; Böhm, S.; Koch, M.

    2018-06-01

    We determined the THz properties of 12 different adhesives which are mainly used for industrial purposes. The adhesives applied can be classified according to their chemical structure: epoxy resins, acrylic resins, and polyurethane based materials. This work represents a basis for future studies, which will concentrate on aging effects, including the absorption of water of adhesive joints. Thus, the dielectric properties of the unaged adhesives are investigated and the results of these measurements are described herein.

  1. A mechanical model of biomimetic adhesive pads with tilted and hierarchical structures.

    Science.gov (United States)

    Schargott, M

    2009-06-01

    A 3D model for hierarchical biomimetic adhesive pads is constructed. It is based on the main principles of the adhesive pads of the Tokay gecko and consists of hierarchical layers of vertical or tilted beams, where each layer is constructed in such a way that no cohesion between adjacent beams can occur. The elastic and adhesive properties are calculated analytically and numerically. For the adhesive contact on stochastically rough surfaces, the maximum adhesion force increases with increasing number of hierarchical layers. Additional calculations show that the adhesion force also depends on the height spectrum of the rough surface.

  2. A mechanical model of biomimetic adhesive pads with tilted and hierarchical structures

    Energy Technology Data Exchange (ETDEWEB)

    Schargott, M [Institute of Mechanics, Technische Universitaet Berlin, Strd 17 Juni 135, 10623 Berlin (Germany)], E-mail: martin.schargott@tu-berlin.de

    2009-06-01

    A 3D model for hierarchical biomimetic adhesive pads is constructed. It is based on the main principles of the adhesive pads of the Tokay gecko and consists of hierarchical layers of vertical or tilted beams, where each layer is constructed in such a way that no cohesion between adjacent beams can occur. The elastic and adhesive properties are calculated analytically and numerically. For the adhesive contact on stochastically rough surfaces, the maximum adhesion force increases with increasing number of hierarchical layers. Additional calculations show that the adhesion force also depends on the height spectrum of the rough surface.

  3. A mechanical model of biomimetic adhesive pads with tilted and hierarchical structures

    International Nuclear Information System (INIS)

    Schargott, M

    2009-01-01

    A 3D model for hierarchical biomimetic adhesive pads is constructed. It is based on the main principles of the adhesive pads of the Tokay gecko and consists of hierarchical layers of vertical or tilted beams, where each layer is constructed in such a way that no cohesion between adjacent beams can occur. The elastic and adhesive properties are calculated analytically and numerically. For the adhesive contact on stochastically rough surfaces, the maximum adhesion force increases with increasing number of hierarchical layers. Additional calculations show that the adhesion force also depends on the height spectrum of the rough surface

  4. Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

    Science.gov (United States)

    Cikanek, Susan R.

    1994-01-01

    An regenerative antiskid braking and traction control system using fuzzy logic for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensor and determining if regenerative antiskid braking control, requiring hydraulic braking control, and requiring traction control are required. The processor then employs fuzzy logic based on the determined vehicle state and provides command signals to a motor controller to control operation of the electric traction motor and to the brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative braking control, hydraulic braking control, and traction control.

  5. Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

    Science.gov (United States)

    Cikanek, S.R.

    1994-10-25

    An regenerative antiskid braking and traction control system using fuzzy logic for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensor and determining if regenerative antiskid braking control, requiring hydraulic braking control, and requiring traction control are required. The processor then employs fuzzy logic based on the determined vehicle state and provides command signals to a motor controller to control operation of the electric traction motor and to the brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative braking control, hydraulic braking control, and traction control. 123 figs.

  6. The role played by the Coulombic traction for an interface crack in dissimilar piezoelectric materials

    International Nuclear Information System (INIS)

    Li Qun; Chen Yiheng

    2008-01-01

    The role played by the Coulombic traction for an interface crack in dissimilar piezoelectric materials is clarified. Based on the extended Stroh theory, the Coulombic traction, usually neglected in piezoelectric fracture, is imposed on the interface crack surfaces. It is found that the low-capacitance medium (air or vacuum) inside the crack gap yields some large Coulombic traction as compared to the applied mechanical loading whether the remanent polarization of piezoelectric material is considered or not. Thus, previous investigations based on the traction-free condition underestimate the role of the Coulombic traction and in turn may yield unexpected errors for the effective stress intensity factor (SIF) and energy release rate (ERR) at the crack tip. (technical note)

  7. PH dependent adhesive peptides

    Science.gov (United States)

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  8. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    . As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will become...

  9. Force sensing using 3D displacement measurements in linear elastic bodies

    Science.gov (United States)

    Feng, Xinzeng; Hui, Chung-Yuen

    2016-07-01

    In cell traction microscopy, the mechanical forces exerted by a cell on its environment is usually determined from experimentally measured displacement by solving an inverse problem in elasticity. In this paper, an innovative numerical method is proposed which finds the "optimal" traction to the inverse problem. When sufficient regularization is applied, we demonstrate that the proposed method significantly improves the widely used approach using Green's functions. Motivated by real cell experiments, the equilibrium condition of a slowly migrating cell is imposed as a set of equality constraints on the unknown traction. Our validation benchmarks demonstrate that the numeric solution to the constrained inverse problem well recovers the actual traction when the optimal regularization parameter is used. The proposed method can thus be applied to study general force sensing problems, which utilize displacement measurements to sense inaccessible forces in linear elastic bodies with a priori constraints.

  10. Bacterial interaction forces in adhesion dynamics

    NARCIS (Netherlands)

    Boks, Niels Peter

    2009-01-01

    Wanneer interactiekrachten tussen bacteriën en oppervlakken bepaald worden, hangen deze erg af van de gebruikte meettechniek. De mechanismen die verantwoordelijk zijn voor deze verschillen zijn echter nog niet duidelijk. Om hier meer inzicht in te krijgen, zijn in dit onderzoek interactiekrachten

  11. Novel Transverse Flux Machine for Vehicle Traction Applications: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Z.; Ahmed, A.; Husain, I.; Muljadi, E.

    2015-04-02

    A novel transverse flux machine topology for electric vehicle traction applications using ferrite magnets is presented in this paper. The proposed transverse flux topology utilizes novel magnet arrangements in the rotor that are similar to the Halbach array to boost flux linkage; on the stator side, cores are alternately arranged around a pair of ring windings in each phase to make use of the entire rotor flux that eliminates end windings. Analytical design considerations and finite-element methods are used for an optimized design of a scooter in-wheel motor. Simulation results from finite element analysis (FEA) show that the motor achieved comparable torque density to conventional rare-earth permanent magnet (PM) machines. This machine is a viable candidate for direct-drive applications with low cost and high torque density.

  12. Syntegra: complete integration of traction, bogie and brake systems

    Energy Technology Data Exchange (ETDEWEB)

    Loewenstein, L.; Wangelin, F. von [Siemens AG, Transportation Systems, Erlangen (Germany). Group Technology TS GT; Teichmann, M.; Hoffmann, T. [Siemens TS, Graz (Austria); Joeckel, A. [Siemens Automation and Drives, Nuernberg (Germany)

    2007-07-01

    With Syntegra {sup registered} technology, Siemens has developed an approach to the complete integration of traction, bogie and brake systems, and this has initially been put into practice for metro, underground and S-Bahn (urban regional express) trains. Syntegra constitutes a fundamentally new approach, achieving a greater intensity of integration compared with the types of drive system that have been in use up until now. With Syntegra, the bogie, transmission and brake components are all brought together as part of one and the same system. The integration and, more especially, the technological advances within the three named areas bring about numerous synergies. The new generation of powered bogie features a combination of high efficiency, low dead weight and reduced emissions. A Syntegra drive system achieves a performance which is markedly better than that of conventional systems. (orig.)

  13. Traction for low back pain with or without sciatica: an updated systematic review within the framework of the Cochrane collaboration

    NARCIS (Netherlands)

    Clarke, J.; van Tulder, M.; Blomberg, S; de Vet, H.C.W.; van der Heijden, G; Bronfort, G.

    2006-01-01

    STUDY DESIGN. Systematic review. OBJECTIVE. To determine if traction is more effective than reference treatments, placebo/sham traction, or no treatment for low back pain (LBP). SUMMARY OF BACKGROUND DATA. Various types of traction are used in the treatment of LBP, often in conjunction with other

  14. Preparation and characterization of UV-curable cationic composite adhesive

    International Nuclear Information System (INIS)

    Shen Yan; Yang Wenbin; Li Yintao; Xie Changqiong; Li Yingjun; Cheng Yafei; Zhou Yuanlin; Lu Zhongyuan

    2011-01-01

    UV-curable cationic composite adhesives containing TiO 2 nanostructures were prepared by using 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate(CE) as monomer, triphenylsulfonium hexafluorophosphate salt (PI-432) as photoinitiator and titanium isopropoxide (TIP) as inorganic precursor. The morphology of the composite adhesives was characterized by atom force microscopy (AFM). The effect of TIP content on refractive index and transmittance of adhesives were studied. The results show that TiO 2 nanostructures, the average diameter of which is 20 nm or so, can be uniformly dispersed in polymers of composite adhesives. The refractive index of adhesives can be adjusted from 1.501 9 to 1.544 9 with the change of TIP content. The transmittance of adhesives has a slight reduce with the increase of TIP content. When TIP content is up to 40%, the transmittance of composite adhesives remains around 90% or so. (authors)

  15. On the Adhesion performance of a single electrospun fiber

    Science.gov (United States)

    Baji, Avinash; Zhou, Limin; Mai, Yiu-Wing; Yang, Zhifang; Yao, Haimin

    2015-01-01

    The micro- and nano-scale fibrillar structures found on the feet of spiders and geckos function as adhesion devices which allow them to adhere to both molecularly smooth and rough surfaces. This adhesion has been argued to arise from intermolecular forces, such as van der Waals (vdW) force, acting at the interface between any two materials in contact. Thus, it is possible to mimic their adhesion using synthetic nanostructured analogs. Herein, we report the first successful pull-off force measurements on a single electrospun fiber and show the potential of using electrospinning to fabricate adhesive analogs. A single fiber is glued to the atomic force microscope cantilever, and its adhesion to a metal substrate is studied by recording the pull-off force/displacement curves. The measured adhesive force of ~18 nN matches closely that of their biological counterparts. Similar to natural structures, the adhesive mechanism of these electrospun structures is controlled by vdW interactions.

  16. Hierarchical capillary adhesion of microcantilevers or hairs

    International Nuclear Information System (INIS)

    Liu Jianlin; Feng Xiqiao; Xia Re; Zhao Hongping

    2007-01-01

    As a result of capillary forces, animal hairs, carbon nanotubes or nanowires of a periodically or randomly distributed array often assemble into hierarchical structures. In this paper, the energy method is adopted to analyse the capillary adhesion of microsized hairs, which are modelled as clamped microcantilevers wetted by liquids. The critical conditions for capillary adhesion of two hairs, three hairs or two bundles of hairs are derived in terms of Young's contact angle, elastic modulus and geometric sizes of the beams. Then, the hierarchical capillary adhesion of hairs is addressed. It is found that for multiple hairs or microcantilevers, the system tends to take a hierarchical structure as a result of the minimization of the total potential energy of the system. The level number of structural hierarchy increases with the increase in the number of hairs if they are sufficiently long. Additionally, we performed experiments to verify our theoretical solutions for the adhesion of microbeams

  17. Analysis methods of stochastic transient electro–magnetic processes in electric traction system

    Directory of Open Access Journals (Sweden)

    T. M. Mishchenko

    2013-04-01

    Full Text Available Purpose. The essence and basic characteristics of calculation methods of transient electromagnetic processes in the elements and devices of non–linear dynamic electric traction systems taking into account the stochastic changes of voltages and currents in traction networks of power supply subsystem and power circuits of electric rolling stock are developed. Methodology. Classical methods and the methods of non–linear electric engineering, as well as probability theory method, especially the methods of stationary ergodic and non–stationary stochastic processes application are used in the research. Findings. Using the above-mentioned methods an equivalent circuit and the system of nonlinear integra–differential equations for electromagnetic condition of the double–track inter-substation zone of alternating current electric traction system are drawn up. Calculations allow obtaining electric traction current distribution in the areas of feeder zones. Originality. First of all the paper is interesting and important from scientific point of view due to the methods, which allow taking into account probabilistic character of change for traction voltages and electric traction system currents. On the second hand the researches develop the most efficient methods of nonlinear circuits’ analysis. Practical value. The practical value of the research is presented in application of the methods to the analysis of electromagnetic and electric energy processes in the traction power supply system in the case of high-speed train traffic.

  18. Traction bronchiectasis in cryptogenic fibrosing alveolitis: associated computed tomographic features and physiological significance

    Energy Technology Data Exchange (ETDEWEB)

    Desai, Sujal R. [Department of Radiology, King' s College Hospital, Denmark Hill, SE5 9RS, London (United Kingdom); Wells, Athol U.; Bois, Roland M. du [Interstitial Lung Disease Unit, Royal Brompton Hospital, Emmanuel Kaye Building, Manresa Road, Fulham, SW6 6LR, London (United Kingdom); Rubens, Michael B.; Hansell, David M. [Department of Radiology, Royal Brompton Hospital, Sydney Street, SW3 6NP, London (United Kingdom)

    2003-08-01

    Our objective was to evaluate the associated CT features and physiological consequences of traction bronchiectasis in patients with cryptogenic fibrosing alveolitis (CFA). The CT scans of 212 patients with CFA (158 men, 54 women; mean age 62.2{+-}10.6 years) were evaluated independently by two observers. The extent of fibrosis, the proportions of a reticular pattern and ground-glass opacification and the extent of emphysema were scored at five levels. The predominant CT pattern, coarseness of a reticular pattern and severity of traction bronchiectasis were graded semiquantitatively. Physiological indices were correlated with CT features. There was traction bronchiectasis on CT in 202 of 212 (95%) patients. Increasingly severe traction bronchiectasis was independently associated with increasingly extensive CFA (p<0.0005), a coarser reticular pattern (p<0.001), a lower proportion of ground-glass opacification (p<0.005) and less extensive emphysema (p<0.0005). Increasingly severe traction bronchiectasis was independently related to depression of DL{sub CO} (p<0.005), FVC (p=0.02) and pO{sub 2} (p<0.0005), but not indices of air-flow obstruction. In CFA, traction bronchiectasis increases with more extensive disease, a lower proportion of ground-glass opacification and a coarser reticular pattern, but it decreases with concurrent emphysema. Increasingly severe traction bronchiectasis is associated with additional physiological impairment for a given extent of pulmonary fibrosis and emphysema. (orig.)

  19. Leading-process actomyosin coordinates organelle positioning and adhesion receptor dynamics in radially migrating cerebellar granule neurons.

    Science.gov (United States)

    Trivedi, Niraj; Ramahi, Joseph S; Karakaya, Mahmut; Howell, Danielle; Kerekes, Ryan A; Solecki, David J

    2014-12-02

    During brain development, neurons migrate from germinal zones to their final positions to assemble neural circuits. A unique saltatory cadence involving cyclical organelle movement (e.g., centrosome motility) and leading-process actomyosin enrichment prior to nucleokinesis organizes neuronal migration. While functional evidence suggests that leading-process actomyosin is essential for centrosome motility, the role of the actin-enriched leading process in globally organizing organelle transport or traction forces remains unexplored. We show that myosin ii motors and F-actin dynamics are required for Golgi apparatus positioning before nucleokinesis in cerebellar granule neurons (CGNs) migrating along glial fibers. Moreover, we show that primary cilia are motile organelles, localized to the leading-process F-actin-rich domain and immobilized by pharmacological inhibition of myosin ii and F-actin dynamics. Finally, leading process adhesion dynamics are dependent on myosin ii and F-actin. We propose that actomyosin coordinates the overall polarity of migrating CGNs by controlling asymmetric organelle positioning and cell-cell contacts as these cells move along their glial guides.

  20. Surgical management of retinal diseases: proliferative diabetic retinopathy and traction retinal detachment.

    Science.gov (United States)

    Cruz-Iñigo, Yousef J; Acabá, Luis A; Berrocal, Maria H

    2014-01-01

    Current indications for pars plana vitrectomy in patients with proliferative diabetic retinopathy (PDR) include vitreous hemorrhage, tractional retinal detachment (TRD), combined tractional and rhegmatogenous retinal detachment (CTRRD), diabetic macular edema associated with posterior hyaloidal traction, and anterior segment neovascularization with media opacities. This chapter will review the indications, surgical objectives, adjunctive pharmacotherapy, microincision surgical techniques, and outcomes of diabetic vitrectomy for PDR, TRD, and CTRRD. With the availability of new microincision vitrectomy technology, wide-angle microscope viewing systems, and pharmacologic agents, vitrectomy can improve visual acuity and achieve long-term anatomic stability in eyes with severe complications from PDR. © 2014 S. Karger AG, Basel

  1. Geckos as Springs: Mechanics Explain Across-Species Scaling of Adhesion.

    Science.gov (United States)

    Gilman, Casey A; Imburgia, Michael J; Bartlett, Michael D; King, Daniel R; Crosby, Alfred J; Irschick, Duncan J

    2015-01-01

    One of the central controversies regarding the evolution of adhesion concerns how adhesive force scales as animals change in size, either among or within species. A widely held view is that as animals become larger, the primary mechanism that enables them to climb is increasing pad area. However, prior studies show that much of the variation in maximum adhesive force remains unexplained, even when area is accounted for. We tested the hypothesis that maximum adhesive force among pad-bearing gecko species is not solely dictated by toepad area, but also depends on the ratio of toepad area to gecko adhesive system compliance in the loading direction, where compliance (C) is the change in extension (Δ) relative to a change in force (F) while loading a gecko's adhesive system (C = dΔ/dF). Geckos are well-known for their ability to climb on a range of vertical and overhanging surfaces, and range in mass from several grams to over 300 grams, yet little is understood of the factors that enable adhesion to scale with body size. We examined the maximum adhesive force of six gecko species that vary in body size (~2-100 g). We also examined changes between juveniles and adults within a single species (Phelsuma grandis). We found that maximum adhesive force and toepad area increased with increasing gecko size, and that as gecko species become larger, their adhesive systems become significantly less compliant. Additionally, our hypothesis was supported, as the best predictor of maximum adhesive force was not toepad area or compliance alone, but the ratio of toepad area to compliance. We verified this result using a synthetic "model gecko" system comprised of synthetic adhesive pads attached to a glass substrate and a synthetic tendon (mechanical spring) of finite stiffness. Our data indicate that increases in toepad area as geckos become larger cannot fully account for increased adhesive abilities, and decreased compliance must be included to explain the scaling of adhesion in

  2. Adhesion mechanisms of nanoparticle silver to substrate materials: identification

    International Nuclear Information System (INIS)

    Joo, Sungchul; Baldwin, Daniel F

    2010-01-01

    Nanoparticle silver (NPS) conductors are increasingly being investigated for printed electronics applications. However, the adhesion mechanism of the nanoparticle silver to substrate materials has not been identified yet. In particular, the adhesion of NPS to organic materials such as the widely used polyimide Kapton HN and Kapton FPC dry films is concerned with low adhesion strength because the processed polymer surface is chemically inert. Moreover, its adhesion to substrate materials such as benzocyclobutene (BCB), copper and aluminum was found to be very weak. Therefore, in this paper, the mechanisms of NPS adhesion to organic and inorganic materials are identified as the first step in improving NPS adhesion strength. Improving the adhesion strength of NPS will be the key issue for printed electronics applications. The adhesion of NPS to substrate materials was found to be mainly attributed to van der Waals forces based on particle adhesion mechanisms. This finding provides the initiative of developing an adhesion prediction model of NPS to substrate materials in order to provide guidelines for improving the NPS adhesion strength to the substrate materials used in printed electronics.

  3. Corrosion, haemocompatibility and bacterial adhesion behaviour of ...

    Indian Academy of Sciences (India)

    TiZrN coating was deposited on 316L stainless steel (SS) by the reactive magnetron co-sputtering technique. Cubic phase of TiZrN with uniform surface morphology was observed by X-ray diffraction and atomic force microscopy. Bacterial adhesion, haemocompatibility and corrosion behaviour of TiZrN coating were ...

  4. Energetics of bacterial adhesion

    International Nuclear Information System (INIS)

    Loosdrecht, M.C.M. van; Zehnder, A.J.B.

    1990-01-01

    For the description of bacterial adhesion phenomena two different physico-chemical approaches are available. The first one, based on a surface Gibbs energy balance, assumes intimate contact between the interacting surfaces. The second approach, based on colloid chemical theories (DLVO theory), allows for two types of adhesion: 1) secondary minimum adhesion, which is often weak and reversible, and 2) irreversible primary minimum adhesion. In the secondary minimum adhesion a thin water film remains present between the interacting surface. The merits of both approaches are discussed in this paper. In addition, the methods available to measure the physico-chemical surface characteristics of bacteria and the influence of adsorbing (in)organic compounds, extracellular polymers and cell surface appendages on adhesion are summarized. (author) 2 figs., 1 tab., 50 refs

  5. Radiation-curable adhesives

    International Nuclear Information System (INIS)

    Woods, J.G.

    1992-01-01

    Radiation-curable adhesives may be classified into two broad categories. In the first category, adhesive bonding occurs as a direct result of irradiation. The second category includes pressure-sensitive and hot-melt adhesives, which are composed of linear or lightly cross-linked polymers prepared by a radiation-induced polymerization reaction. This chapter is mainly concerned with radiation-curable adhesives of the first category. The various adhesive types are discussed and adhesive performance is examined, particularly in relation to the chemistry and chemical technology which underlies the individual materials. A description of a limited number of representative applications is included as is an outline of recent developments of curing and dispensing equipment. 268 refs., 14 figs., 13 tabs

  6. The adhesive strength and initial viscosity of denture adhesives.

    Science.gov (United States)

    Han, Jian-Min; Hong, Guang; Dilinuer, Maimaitishawuti; Lin, Hong; Zheng, Gang; Wang, Xin-Zhi; Sasaki, Keiichi

    2014-11-01

    To examine the initial viscosity and adhesive strength of modern denture adhesives in vitro. Three cream-type denture adhesives (Poligrip S, Corect Cream, Liodent Cream; PGS, CRC, LDC) and three powder-type denture adhesives (Poligrip Powder, New Faston, Zanfton; PGP, FSN, ZFN) were used in this study. The initial viscosity was measured using a controlled-stress rheometer. The adhesive strength was measured according to ISO-10873 recommended procedures. All data were analyzed independently by one-way analysis of variance combined with a Student-Newman-Keuls multiple comparison test at a 5% level of significance. The initial viscosity of all the cream-type denture adhesives was lower than the powder-type adhesives. Before immersion in water, all the powder-type adhesives exhibited higher adhesive strength than the cream-type adhesives. However, the adhesive strength of cream-type denture adhesives increased significantly and exceeded the powder-type denture adhesives after immersion in water. For powder-type adhesives, the adhesive strength significantly decreased after immersion in water for 60 min, while the adhesive strength of the cream-type adhesives significantly decreased after immersion in water for 180 min. Cream-type denture adhesives have lower initial viscosity and higher adhesive strength than powder type adhesives, which may offer better manipulation properties and greater efficacy during application.

  7. Synaptic Cell Adhesion

    OpenAIRE

    Missler, Markus; Südhof, Thomas C.; Biederer, Thomas

    2012-01-01

    Chemical synapses are asymmetric intercellular junctions that mediate synaptic transmission. Synaptic junctions are organized by trans-synaptic cell adhesion molecules bridging the synaptic cleft. Synaptic cell adhesion molecules not only connect pre- and postsynaptic compartments, but also mediate trans-synaptic recognition and signaling processes that are essential for the establishment, specification, and plasticity of synapses. A growing number of synaptic cell adhesion molecules that inc...

  8. The Effect of 2 Forms of Talocrural Joint Traction on Dorsiflexion Range of Motion and Postural Control in Those With Chronic Ankle Instability.

    Science.gov (United States)

    Powden, Cameron J; Hogan, Kathleen K; Wikstrom, Erik A; Hoch, Matthew C

    2017-05-01

    Talocrural joint mobilizations are commonly used to address deficits associated with chronic ankle instability (CAI). Examine the immediate effects of talocrural joint traction in those with CAI. Blinded, crossover. Laboratory. Twenty adults (14 females; age = 23.80 ± 4.02 y; height = 169.55 ± 12.38 cm; weight = 78.34 ± 16.32 kg) with self-reported CAI participated. Inclusion criteria consisted of a history of ≥1 ankle sprain, ≥2 episodes of giving way in the previous 3 mo, answering "yes" to ≥4 questions on the Ankle Instability Instrument, and ≤24 on the Cumberland Ankle Instability Tool. Subjects participated in 3 sessions in which they received a single treatment session of sustained traction (ST), oscillatory traction (OT), or a sham condition in a randomized order. Interventions consisted of four 30-s sets of traction with 1 min of rest between sets. During ST and OT, the talus was distracted distally from the ankle mortise to the end-range of accessory motion. ST consisted of continuous distraction and OT involved 1-s oscillations between the mid and end-range of accessory motion. The sham condition consisted of physical contact without force application. Preintervention and postintervention measurements of weight-bearing dorsiflexion, dynamic balance, and static single-limb balance were collected. The independent variable was treatment (ST, OT, sham). The dependent variables included pre-to-posttreatment change scores for the WBLT (cm), normalized SEBTAR (%), and time-to-boundary (TTB) variables(s). Separate 1-way ANOVAs examined differences between treatments for each dependent variable. Alpha was set a priori at P manual therapies.

  9. Reversible Thermoset Adhesives

    Science.gov (United States)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  10. A novel anchorage technique for transnasal traction in rigid external maxillary distraction.

    Science.gov (United States)

    Varol, A; Basa, S

    2013-12-01

    We describe an effective technique for anchorage of transnasal traction in the management of maxillary rotation during external distraction. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  11. Basilar impression in osteogenesis imperfecta: can it be treated with halo traction and posterior fusion?

    NARCIS (Netherlands)

    Noske, D. P.; van Royen, B. J.; Bron, J. L.; Vandertop, W. P.

    2006-01-01

    Basilar impression (BI) and hydrocephalus complicating osteogenesis imperfecta (OI) is usually treated by anterior transoral decompression and posterior fixation. Nevertheless, it may be questioned if posterior fusion following axial halo traction is adequate in patients with symptomatic BI

  12. Performance Analysis of Permanent Magnet Motors for Electric Vehicles (EV Traction Considering Driving Cycles

    Directory of Open Access Journals (Sweden)

    Thanh Anh Huynh

    2018-05-01

    Full Text Available This paper evaluates the electromagnetic and thermal performance of several traction motors for electric vehicles (EVs. Two different driving cycles are employed for the evaluation of the motors, one for urban and the other for highway driving. The electromagnetic performance to be assessed includes maximum motor torque output for vehicle acceleration and the flux weakening capability for wide operating range under current and voltage limits. Thermal analysis is performed to evaluate the health status of the magnets and windings for the prescribed driving cycles. Two types of traction motors are investigated: two interior permanent magnet motors and one permanent magnet-assisted synchronous reluctance motor. The analysis results demonstrate the benefits and disadvantages of these motors for EV traction and provide suggestions for traction motor design. Finally, experiments are conducted to validate the analysis.

  13. Protein Modifiers Generally Provide Limited Improvement in Wood Bond Strength of Soy Flour Adhesives

    Science.gov (United States)

    Charles R. Frihart; Linda Lorenz

    2013-01-01

    Soy flour adhesives using a polyamidoamine-epichlorohydrin (PAE) polymeric coreactant are used increasingly as wood adhesives for interior products. Although these adhesives give good performance, higher bond strength under wet conditions is desirable. Wet strength is important for accelerated tests involving the internal forces generated by the swelling of wood and...

  14. Modular PM Motor Drives for Automotive Traction Applications

    International Nuclear Information System (INIS)

    Su, G.J.

    2001-01-01

    This paper presents modular permanent magnet (PM) motor drives for automotive traction applications. A partially modularized drive system consisting of a single PM motor and multiple inverters is described. The motor has multiple three-phase stator winding sets and each winding set is driven with a separate three-phase inverter module. A truly modularized inverter and motor configuration based on an axial-gap PM motor is then introduced, in which identical PM motor modules are mounted on a common shaft and each motor module is powered by a separate inverter module. The advantages of the modular approach for both inverter and motor include: (1) power rating scalability-one design meets different power requirements by simply stacking an adequate number of modules, thus avoiding redesigning and reducing the development cost, (2) increased fault tolerance, and (3) easy repairing. A prototype was constructed by using two inverters and an axial-gap PM motor with two sets of three-phase stat or windings, and it is used to assist the diesel engine in a hybrid electric vehicle converted from a Chevrolet Suburban. The effect of different pulse-width-modulation strategies for both motoring and regenerative modes on current control is analyzed. Torque and regenerative control algorithms are implemented with a digital signal processor. Analytical and initial testing results are included in the paper

  15. Traction suture modification to tongue-in-groove caudal septoplasty.

    Science.gov (United States)

    Indeyeva, Y A; Lee, T S; Gordin, E; Chan, D; Ducic, Y

    2018-02-01

    Caudal septal deviation leads to unfavorable esthetic as well as functional effects on the nasal airway. A modification to the tongue-in-groove (TIG) technique to correct these caudal septal deformities is described. With placement of a temporary suspension suture to the caudal septum, manual traction is applied, assuring that the caudal septum remains in the midline position while it is being secured with multiple through-and-through, trans-columellar and trans-septal sutures. From 2003 to 2016, 148 patients underwent endonasal septoplasty using this modified technique, with excellent functional and cosmetic outcomes and a revision rate of 1.4%. This modified TIG technique replaces the periosteal suture that secures the caudal septum to the midline nasal crest in the original TIG technique. This simplifies the procedure and minimizes the risk of securing the caudal septum off-midline when used in endonasal septoplasty. Copyright © 2017 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  16. Repeated origin and loss of adhesive toepads in geckos.

    Directory of Open Access Journals (Sweden)

    Tony Gamble

    Full Text Available Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive mechanism, but lack of a comprehensive phylogeny has hindered efforts to determine how frequently adhesive toepads have been gained and lost. Here we present a multigene phylogeny of geckos, including 107 of 118 recognized genera, and determine that adhesive toepads have been gained and lost multiple times, and remarkably, with approximately equal frequency. The most likely hypothesis suggests that adhesive toepads evolved 11 times and were lost nine times. The overall external morphology of the toepad is strikingly similar in many lineages in which it is independently derived, but lineage-specific differences are evident, particularly regarding internal anatomy, with unique morphological patterns defining each independent derivation.

  17. Repeated origin and loss of adhesive toepads in geckos.

    Science.gov (United States)

    Gamble, Tony; Greenbaum, Eli; Jackman, Todd R; Russell, Anthony P; Bauer, Aaron M

    2012-01-01

    Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads) that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive mechanism, but lack of a comprehensive phylogeny has hindered efforts to determine how frequently adhesive toepads have been gained and lost. Here we present a multigene phylogeny of geckos, including 107 of 118 recognized genera, and determine that adhesive toepads have been gained and lost multiple times, and remarkably, with approximately equal frequency. The most likely hypothesis suggests that adhesive toepads evolved 11 times and were lost nine times. The overall external morphology of the toepad is strikingly similar in many lineages in which it is independently derived, but lineage-specific differences are evident, particularly regarding internal anatomy, with unique morphological patterns defining each independent derivation.

  18. Sustainability Aspects of Energy Conversion in Modern High-Speed Trains with Traction Induction Motors

    OpenAIRE

    Marc A. Rosen; Doru A. Nicola; Cornelia A. Bulucea; Daniel C. Cismaru

    2015-01-01

    Some aspects are illustrated of energy conversion processes during the operation of electric railway vehicles with traction induction motors, in order to support transport systems’ sustainability. Increasing efforts are being expended to enhance the sustainability of transportation technologies and systems. Since electric drive systems are used with variable voltage variable frequency (VVVF) inverters and traction induction motors, these machines with appropriate controls can realize both tra...

  19. Group traction drive as means to increase energy efficiency of lokomotives of open-pit transport

    Science.gov (United States)

    Antipin, D. Ya; Izmerov, O. V.; Bishutin, S. G.; Kobishchanov, V. V.

    2017-10-01

    Questions of possible use of a group drive for locomotives of an open-pit transport are considered. The possibility of a significant reduction of traction costs in the case of a combination of a group traction drive with devices for the non-inertial regulation of the coefficient of friction between the wheel and the rail has been shown, and new patentable solutions have been proposed.

  20. Innovative Electrostatic Adhesion Technologies

    Science.gov (United States)

    Bryan, Tom; Macleod, Todd; Gagliano, Larry; Williams, Scott; McCoy, Brian

    2015-01-01

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA gripper pad surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and

  1. Changes in materials properties explain the effects of humidity on gecko adhesion.

    Science.gov (United States)

    Puthoff, Jonathan B; Prowse, Michael S; Wilkinson, Matt; Autumn, Kellar

    2010-11-01

    Geckos owe their remarkable stickiness to millions of dry setae on their toes, and the mechanism of adhesion in gecko setae has been the topic of scientific scrutiny for over two centuries. Previously, we demonstrated that van der Waals forces are sufficient for strong adhesion and friction in gecko setae, and that water-based capillary adhesion is not required. However, recent studies demonstrated that adhesion increases with relative humidity (RH) and proposed that surface hydration and capillary water bridge formation is important or even necessary. In this study, we confirmed a significant effect of RH on gecko adhesion, but rejected the capillary adhesion hypothesis. While contact forces of isolated tokay gecko setal arrays increased with humidity, the increase was similar on hydrophobic and hydrophilic surfaces, inconsistent with a capillary mechanism. Contact forces increased with RH even at high shear rates, where capillary bridge formation is too slow to affect adhesion. How then can a humidity-related increase in adhesion and friction be explained? The effect of RH on the mechanical properties of setal β-keratin has escaped consideration until now. We discovered that an increase in RH softens setae and increases viscoelastic damping, which increases adhesion. Changes in setal materials properties, not capillary forces, fully explain humidity-enhanced adhesion, and van der Waals forces remain the only empirically supported mechanism of adhesion in geckos.

  2. The adhesion behavior of carbon coating studied by re-indentation during in situ TEM nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xue; Diao, Dongfeng, E-mail: dfdiao@szu.edu.cn

    2016-01-30

    Graphical abstract: Nanoscale adhesion induced response in terms of re-indentation was directly observed. During unloading (start from B), the re-indentation phenomenon with the displacement sudden drop and the external loading force change from tension (C) to compression (D) within 0.1 s was captured by in situ TEM nanoindentation. - Highlights: • In situ TEM nanoindentation was performed on carbon coating. • Adhesion induced nano-response of re-indentation was directly observed. • Adhesive forces were measured from the load–displacement curves. • Adhesion energies released for re-indentation were quantitatively analyzed. • Carbon coating reduced the impact of adhesion for silicon substrate. - Abstract: We report a nanoscale adhesion induced nano-response in terms of re-indentation during in situ transmission electron microscope (TEM) nanoindentation on the carbon coating with silicon substrate. The adhesive force generated with nanoindentation was measured, and re-indentation phenomenon during unloading with displacement sudden drop and external loading force change from tension to compression was found. The occurrence of re-indentation during unloading was ascribed to the adhesive force of the contact interface between the indenter and the coating surface. Adhesion energies released for re-indentation processes were quantitatively analyzed from the re-indentation load–displacement curves, and carbon coating reduced the impact of adhesion for silicon substrate. The adhesion induced nano-response of contact surfaces would affect the reliability and performance of nano devices.

  3. Spatiotemporal patterns formed by deformed adhesive in peeling

    International Nuclear Information System (INIS)

    Yamazaki, Yoshihiro; Toda, Akihiko

    2007-01-01

    Dynamical properties of peeling an adhesive tape are investigated experimentally as an analogy of sliding friction. An adhesive tape is peeled by pulling an elastic spring connected to the tape. Controlling its spring constant k and pulling speed V, peel force is measured and spatiotemporal patterns formed on the peeled tape by deformed adhesive are observed. It is found that there exist two kinds of adhesive state in peeling front. The emergence of multiple states is caused by the stability of a characteristic structure (tunnel structure) formed by deformed adhesive. Tunnel structures are distributed spatiotemporally on adhesive tape after peeling. Based on the spatiotemporal distribution, a morphology-dynamical phase diagram is constructed on k-V space and is divided into the four regions: (A) uniform pattern with tunnel structure, (B) uniform pattern without tunnel structure, (C) striped pattern with oscillatory peeling, and (D) spatiotemporally coexistent pattern

  4. A Study of Torque Vectoring and Traction Control for an All-Wheel Drive Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Maharun Mui’nuddin

    2014-07-01

    Full Text Available Common vehicle always experience energy loss during cornering manoeuver. Thus, to ensure it did not happened especially at high speed, a study of torque vectoring and traction control need to be made since it can increase the traction control of tyres during cornering at high speed. The study of torque vectoring and traction control for an all-wheel drive electric vehicle was conducted by modelling an all-wheel drive electric vehicle (EV in ADAMS/Car software. In addition, an optimal control algorithm will be developed for best performance to minimize energy losses using MATLAB/Simulink software. Furthermore, to prove the effectiveness of the all-wheel drive electric, the torque and traction control simulation of the all-wheel drive electric vehicle will be compared with uncontrolled electric vehicle model. According to the result, torque vectoring and traction control of in-wheel motor in all wheel drive EV can help to increase the performance of the electric vehicle during cornering manoeuver. In conclusion, this study of torque vectoring and traction control for an all-wheel drive electric vehicle will help researchers to improve the design of the future electric vehicle in term of the vehicle performance during cornering manoeuvre.

  5. Acetabular labral tears: contrast-enhanced MR imaging under continuous leg traction

    Energy Technology Data Exchange (ETDEWEB)

    Nishii, T. [Div. of Functional Diagnostic Imaging, Biomedical Research Center, Osaka Univ. Medical School, Suita (Japan); Nakanishi, K. [Dept. of Radiology, Osaka Univ. Medical School, Suita (Japan); Sugano, N. [Dept. of Orthopaedic Surgery, Osaka Univ. Medical School, Suita (Japan); Naito, H. [Div. of Functional Diagnostic Imaging, Biomedical Research Center, Osaka Univ. Medical School, Suita (Japan); Tamura, S. [Div. of Functional Diagnostic Imaging, Biomedical Research Center, Osaka Univ. Medical School, Suita (Japan); Ochi, T. [Dept. of Orthopaedic Surgery, Osaka Univ. Medical School, Suita (Japan)

    1996-05-01

    The objective of this study was to evaluate the effects of continuous leg traction on contrast-enhanced MR imaging of the hip joint and to determine whether MR imaging under these conditions is useful for demonstrating acetabular labral tears. Nineteen hips underwent MR imaging with a T1-weighted spin-echo sequence, followed by MR imaging under continuous leg traction after intravenous injection of gadolinium-DTPA. Joint fluid enhancement and labral contour detection were evaluated. Eleven hips had labral tears shown by conventional arthrography, arthroscopy and macroscopic surgical findings. Assessment of labral tears by MR imaging was correlated with the diagnosis based on these standard techniques. Joint fluid enhancement was obtained in all hips at 30 min after injection. Superior and inferior labral surfaces were completely delineated in 1 hip on the unenhanced MR images, and in 7 and 13 hips, respectively, on the enhanced images under traction. The enhanced images under traction depicted 9 of the 11 labral tears. Comparison between the unenhanced image and the enhanced image under traction avoided mistaking undercutting of the labrum for a tear in 4 hips. Contrast-enhanced MR imaging under traction was valuable for detecting labral tears non-invasively and without radiation. Follow-up examinations using this method in patients with acetabular dysplasia can help to clarify the natural course of labral disorders and enable better treatment planning. (orig./MG)

  6. Traction bronchiectasis in cryptogenic fibrosing alveolitis: associated computed tomographic features and physiological significance

    International Nuclear Information System (INIS)

    Desai, Sujal R.; Wells, Athol U.; Bois, Roland M. du; Rubens, Michael B.; Hansell, David M.

    2003-01-01

    Our objective was to evaluate the associated CT features and physiological consequences of traction bronchiectasis in patients with cryptogenic fibrosing alveolitis (CFA). The CT scans of 212 patients with CFA (158 men, 54 women; mean age 62.2±10.6 years) were evaluated independently by two observers. The extent of fibrosis, the proportions of a reticular pattern and ground-glass opacification and the extent of emphysema were scored at five levels. The predominant CT pattern, coarseness of a reticular pattern and severity of traction bronchiectasis were graded semiquantitatively. Physiological indices were correlated with CT features. There was traction bronchiectasis on CT in 202 of 212 (95%) patients. Increasingly severe traction bronchiectasis was independently associated with increasingly extensive CFA (p CO (p 2 (p<0.0005), but not indices of air-flow obstruction. In CFA, traction bronchiectasis increases with more extensive disease, a lower proportion of ground-glass opacification and a coarser reticular pattern, but it decreases with concurrent emphysema. Increasingly severe traction bronchiectasis is associated with additional physiological impairment for a given extent of pulmonary fibrosis and emphysema. (orig.)

  7. Adhesive interactions with wood

    Science.gov (United States)

    Charles R. Frihart

    2004-01-01

    While the chemistry for the polymerization of wood adhesives has been studied systematically and extensively, the critical aspects of the interaction of adhesives with wood are less clearly understood. General theories of bond formation need to be modified to take into account the porosity of wood and the ability of chemicals to be absorbed into the cell wall....

  8. Adhesive compositions and methods

    Science.gov (United States)

    Allen, Scott D.; Sendijarevic, Vahid; O'Connor, James

    2017-12-05

    The present invention encompasses polyurethane adhesive compositions comprising aliphatic polycarbonate chains. In one aspect, the present invention encompasses polyurethane adhesives derived from aliphatic polycarbonate polyols and polyisocyanates wherein the polyol chains contain a primary repeating unit having a structure:. In another aspect, the invention provides articles comprising the inventive polyurethane compositions as well as methods of making such compositions.

  9. Soy protein adhesives

    Science.gov (United States)

    Charles R. Frihart

    2010-01-01

    In the quest to manufacture and use building materials that are more environmentally friendly, soy adhesives can be an important component. Trees fix and store carbon dioxide in the atmosphere. After the trees are harvested, machinery converts the wood into strands, which are then bonded together with adhesives to form strandboard, used in constructing long-lasting...

  10. Intercellular adhesion molecule-1 augments myoblast adhesion and fusion through homophilic trans-interactions.

    Science.gov (United States)

    Pizza, Francis X; Martin, Ryan A; Springer, Evan M; Leffler, Maxwell S; Woelmer, Bryce R; Recker, Isaac J; Leaman, Douglas W

    2017-07-11

    The overall objective of the study was to identify mechanisms through which intercellular adhesion molecule-1 (ICAM-1) augments the adhesive and fusogenic properties of myogenic cells. Hypotheses were tested using cultured myoblasts and fibroblasts, which do not constitutively express ICAM-1, and myoblasts and fibroblasts forced to express full length ICAM-1 or a truncated form lacking the cytoplasmic domain of ICAM-1. ICAM-1 mediated myoblast adhesion and fusion were quantified using novel assays and cell mixing experiments. We report that ICAM-1 augments myoblast adhesion to myoblasts and myotubes through homophilic trans-interactions. Such adhesive interactions enhanced levels of active Rac in adherent and fusing myoblasts, as well as triggered lamellipodia, spreading, and fusion of myoblasts through the signaling function of the cytoplasmic domain of ICAM-1. Rac inhibition negated ICAM-1 mediated lamellipodia, spreading, and fusion of myoblasts. The fusogenic property of ICAM-1-ICAM-1 interactions was restricted to myogenic cells, as forced expression of ICAM-1 by fibroblasts did not augment their fusion to ICAM-1+ myoblasts/myotubes. We conclude that ICAM-1 augments myoblast adhesion and fusion through its ability to self-associate and initiate Rac-mediated remodeling of the actin cytoskeleton.

  11. Wrist Traction During MR Arthrography Improves Detection of Triangular Fibrocartilage Complex and Intrinsic Ligament Tears and Visibility of Articular Cartilage.

    Science.gov (United States)

    Lee, Ryan K L; Griffith, James F; Ng, Alex W H; Nung, Ryan C H; Yeung, David K W

    2016-01-01

    The purpose of this study was to assess the effects of traction during MR arthrography of the wrist on joint space widening, cartilage visibility, and detection of tears of the triangular fibrocartilage complex (TFCC) and intrinsic ligaments. A prospective study included 40 wrists in 39 patients (25 men, 14 women; mean age, 35 years). MR arthrography was performed with a 3-T MRI system with and without axial traction. Two radiologists independently measured wrist and carpal joint space widths and semiquantitatively graded articular cartilage visibility. Using conventional arthrography as the reference standard and working in consensus, they assessed for the presence of tears of the TFCC, lunotriquetral ligament (LTL), and scapholunate ligament (SLL). Visibility of a tear before traction was compared with visibility after traction. With traction, all joint spaces in the wrist and carpus were significantly widened (change, 0.15-1.01 mm; all p < 0.006). Subjective cartilage visibility of all joint spaces improved after traction (all p ≤ 0.048) except for that of the radioscaphoid space, which was well visualized even before traction. Conventional arthrography depicted 24 TFCC tears, seven LTL tears, and three SLL tears. The accuracy of tear detection improved after traction for the TFCC (98% after traction vs 83% before traction), the LTL (100% vs 88%), and the SLL (100% vs 95%). Tear visibility improved after traction for 54% of TFCC tears, 71% of LTL tears, and 66% of SLL tears. Wrist MR arthrography with axial traction significantly improved the visibility of articular cartilage and the detection and visibility of tears of the TFCC and intrinsic ligaments. The results favor more widespread use of traction during MR arthrography of the wrist.

  12. Controllable biomimetic adhesion using embedded phase change material

    International Nuclear Information System (INIS)

    Krahn, J; Sameoto, D; Menon, C

    2011-01-01

    In many cases, such as in the instance of climbing robots or temporary adhesives, there is the need to be able to dynamically control the level of adhesion a biomimetic dry adhesive can provide. In this study, the effect of changing the backing layer stiffness of a dry adhesive is examined. Embedding a phase change material within the backing of a synthetic dry adhesive sheet allows the stiffness to be tailored at different points of a preload and adhesion cycle. Larger contact areas and more equal load sharing between adhesive fibres can be achieved by increasing the backing layer stiffness after initial deformation when the adhesive backing is loaded in its softened state. Adhesion behaviour is examined when the backing layer is maintained in solid and softened phases during complete load cycles and for load cycles under the condition of contact with the softened phase backing followed by pull-off during the solid phase. Absolute adhesion force is increased for trials in which a soft backing layer hardens prior to pull-off. This effect is due to the increased contact area made between the rounded probe and the softened material during preloading and the more equal load sharing condition during pull-off when the backing layer becomes stiff again

  13. ADHESIVE SYSTEM AFFECTS REPAIR BOND STRENGTH OF RESIN COMPOSITE

    Directory of Open Access Journals (Sweden)

    Özgür IRMAK

    2017-10-01

    Full Text Available Purpose: This study evaluated the effects of different adhesive systems on repair bond strength of aged resin composites. Materials and Methods: Ninety composite discs were built and half of them were subjected to thermal aging. Aged and non-aged specimens were repaired with resin composite using three different adhesive systems; a two-step self-etch adhesive, a two-step total-etch adhesive and a one-step self-etch adhesive; then they were subjected to shear forces. Data were analyzed statistically. Results: Adhesive type and aging significantly affected the repair bond strengths (p<0.0001. No statistical difference was found in aged composite groups repaired with two-step self- etch or two-step total-etch adhesive. One-step self-etch adhesive showed lower bond strength values in aged composite repair (p<0.0001. Conclusion: In the repair of aged resin composite, two-step self-etch and two-step total-etch adhesives exhibited higher shear bond strength values than that of one-step self-etch adhesive.

  14. Reversible low adhesive to high adhesive superhydrophobicity transition on ZnO nanoparticle surfaces

    International Nuclear Information System (INIS)

    Li, Jian; Jing, Zhijiao; Yang, Yaoxia; Zha, Fei; Yan, Long; Lei, Ziqiang

    2014-01-01

    Superhydrophobic ZnO surfaces with water contact angle of 162° and sliding angle of 2° were fabricated successfully by spraying hydrophobic ZnO nanoparticle suspensions without limitations the shape and size of substrates. The as-prepared superhydrophobic ZnO surfaces are low adhesive and a water droplet easily rolls off with the surface slightly tilted. However, after being irradiated by UV light through a photomask, it becomes highly adhesive, on which a water droplet is firmly pinned without any movement. Further annealing the irradiated film, water droplets can roll off the surface again. Reversible transition between the low adhesive rolling state and high adhesive pinning state can be realized simply by UV illumination and heat treatment alternately. At the same time, the maximum adhesive force between the superhydrophobic ZnO surfaces and the water droplet changes from extreme low (∼5.1 μN) to very high (∼136.1 μN). When irradiated without a photomask, the surface became hydrophilic. Additionally, a water droplet can be transfered from the low adhesive superhydrophobic ZnO surfaces to the hydrophilic ZnO surfaces using the high adhesive superhydrophobic ZnO surfaces as a mechanical hand.

  15. Passively stuck: death does not affect gecko adhesion strength.

    Science.gov (United States)

    Stewart, William J; Higham, Timothy E

    2014-12-01

    Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos (Gekko gecko) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  16. Adhesive contact: from atomistic model to continuum model

    International Nuclear Information System (INIS)

    Fan Kang-Qi; Jia Jian-Yuan; Zhu Ying-Min; Zhang Xiu-Yan

    2011-01-01

    Two types of Lennard-Jones potential are widely used in modeling adhesive contacts. However, the relationships between the parameters of the two types of Lennard-Jones potential are not well defined. This paper employs a self-consistent method to derive the Lennard-Jones surface force law from the interatomic Lennard-Jones potential with emphasis on the relationships between the parameters. The effect of using correct parameters in the adhesion models is demonstrated in single sphere-flat contact via continuum models and an atomistic model. Furthermore, the adhesion hysteresis behaviour is investigated, and the S-shaped force-distance relation is revealed by the atomistic model. It shows that the adhesion hysteresis loop is generated by the jump-to-contact and jump-off-contact, which are illustrated by the S-shaped force-distance curve. (atomic and molecular physics)

  17. Adhesion of perfume-filled microcapsules to model fabric surfaces.

    Science.gov (United States)

    He, Yanping; Bowen, James; Andrews, James W; Liu, Min; Smets, Johan; Zhang, Zhibing

    2014-01-01

    The retention and adhesion of melamine formaldehyde (MF) microcapsules on a model fabric surface in aqueous solution were investigated using a customised flow chamber technique and atomic force microscopy (AFM). A cellulose film was employed as a model fabric surface. Modification of the cellulose with chitosan was found to increase the retention and adhesion of microcapsules on the model fabric surface. The AFM force-displacement data reveal that bridging forces resulting from the extension of cellulose chains dominate the adhesion between the microcapsule and the unmodified cellulose film, whereas electrostatic attraction helps the microcapsules adhere to the chitosan-modified cellulose film. The correlation between results obtained using these two complementary techniques suggests that the flow chamber device can be potentially used for rapid screening of the effect of chemical modification on the adhesion of microparticles to surfaces, reducing the time required to achieve an optimal formulation.

  18. Modeling cytoskeletal flow over adhesion sites: competition between stochastic bond dynamics and intracellular relaxation

    International Nuclear Information System (INIS)

    Sabass, Benedikt; Schwarz, Ulrich S

    2010-01-01

    In migrating cells, retrograde flow of the actin cytoskeleton is related to traction at adhesion sites located at the base of the lamellipodium. The coupling between the moving cytoskeleton and the stationary adhesions is mediated by the continuous association and dissociation of molecular bonds. We introduce a simple model for the competition between the stochastic dynamics of elastic bonds at the moving interface and relaxation within the moving actin cytoskeleton represented by an internal viscous friction coefficient. Using exact stochastic simulations and an analytical mean field theory, we show that the stochastic bond dynamics lead to biphasic friction laws as observed experimentally. At low internal dissipation, stochastic bond dynamics lead to a regime of irregular stick-and-slip motion. High internal dissipation effectively suppresses cooperative effects among bonds and hence stabilizes the adhesion.

  19. Electrical Energy Quality Studies in 3 kV DC Electric Traction Systems for Different Schemes of Connection Traction Substation to Power Utility System

    Directory of Open Access Journals (Sweden)

    Leszek Mierzejewski

    2004-01-01

    Full Text Available The paper present aspects of DC electric traction system influence on electric energetic system. Study is based on modeling and simulation of electrified railway line. After simulation, there was performed analysis of energy quality, whitch using results of simulation and supply systems parameters.

  20. Dry adhesives from carbon nanofibers grown in an open ethanol flame

    Directory of Open Access Journals (Sweden)

    Christian Lutz

    2017-12-01

    Full Text Available Based on magnetic-field-assisted growth of carbon nanofibers in an open ethanol flame we fabricated arrays of carbon nanofibers with different degrees of orientation. Inspired by the dry adhesive system of geckos we investigated the adhesive properties of such carbon nanofiber arrays with ordered and random orientation. AFM-based force spectroscopy revealed that adhesion force and energy rise linear with preload force. Carbon nanofibers oriented by a magnetic field show a 68% higher adhesion (0.66 N/cm2 than the randomly oriented fibers. Endurance tests revealed that the carbon nanofiber arrays withstand 50.000 attachment/detachment cycles without observable wear.

  1. Partial-thickness macular hole in vitreomacular traction syndrome: a case report and review of the literature

    Directory of Open Access Journals (Sweden)

    Al Sabti Khalid

    2010-01-01

    Full Text Available Abstract Introduction Vitreomacular traction syndrome has recently been recognized as a distinct clinical condition. It may lead to many complications, such as cystoid macular edema, macular pucker formation, tractional macular detachment, and full-thickness macular hole formation. Case presentation We report a case of vitreomacular traction syndrome with eccentric traction at the macula and a partial-thickness macular hole in a 63-year-old Pakistani Punjabi man. The patient was evaluated using optical coherence tomography, and he underwent a successful pars plana vitrectomy. After the operation, his foveal contour regained normal configuration, and his visual acuity improved from 20/60 to 20/30. Conclusions Pars plana vitrectomy prevents the progression of a partial thickness macular hole in vitreomacular traction syndrome. The relief of traction by vitrectomy restores foveal anatomy and visual acuity in this condition.

  2. Oracle9i database gains traction among leading European customers

    CERN Multimedia

    2002-01-01

    The Oracle Corporation software group, today announced that more than 600 customers worldwide have purchased Oracle9i Real Application Clusters. Some of the European customers include Austrian Railways, BACS, Bavarian Police Force, CERN, e-Spatial, Navision a/s and the North Rhine-Westphalia Police Force.

  3. EB curable laminating adhesives

    International Nuclear Information System (INIS)

    Matsuyama, Asao; Kobayashi, Masahide; Gotoh, Sakiko

    1992-01-01

    New developed solvent free EB curable laminating adhesives have two liquid components, A with hydroxy and acryloyl group, B with isocyanate and acryloyl group in a molecule. These EB laminating adhesives do not need any aging process, which is a big advantage, and are very suitable for environment, safety, and health because of no heating process and solvent free formulas. And we have made basic research about the relation of peel strength or heat seal strength versus Tg of cured film, elongation at break, elastic modulus, and so on. Basic specifications of the new developed adhesives are shown. (author)

  4. Adhesive and morphological characteristics of surface chemically modified polytetrafluoroethylene films

    International Nuclear Information System (INIS)

    Hopp, B.; Kresz, N.; Kokavecz, J.; Smausz, T.; Schieferdecker, H.; Doering, A.; Marti, O.; Bor, Z.

    2004-01-01

    In the present paper, we report an experimental determination of adhesive and topographic characteristics of chemically modified surface of polytetrafluoroethylene (PTFE) films. The surface chemistry was modified by ArF excimer laser irradiation in presence of triethylene-tetramine photoreagent. The applied laser fluence was varied in the range of 0.4-9 mJ/cm 2 , and the number of laser pulses incident on the same area was 1500. To detect the changes in the adhesive features of the treated Teflon samples, we measured receding contact angle for distilled water and adhesion strength, respectively. It was found that the receding contact angle decreased from 96 deg. to 30-37 deg. and the adhesion strength of two-component epoxy glue to the treated sample surface increased from 0.03 to 9 MPa in the applied laser fluence range. Additionally, it was demonstrated that the adhesion of human cells to the modified Teflon samples is far better than to the untreated ones. The contact mode and pulsed force mode atomic force microscopic investigations of the treated samples demonstrated that the measured effective contact area of the irradiated films does not differ significantly from that of the original films, but the derived adhesion force is stronger on the modified samples than on the untreated ones. Hence, the increased adhesion of the treated Teflon films is caused by the higher surface energy

  5. Quantitative analysis of the orthodontic and orthopedic effects of maxillary traction.

    Science.gov (United States)

    Baumrind, S; Korn, E L; Isaacson, R J; West, E E; Molthen, R

    1983-11-01

    This article analyzes differences in displacement of ANS and of the upper first molar when different vectors of force are delivered to the maxilla in non-full-banded Phase I mixed-dentition treatment of Class II malocclusion. The sample is identical to that for which we have previously reported differences in change in several key measures of mandibular and facial shape. It includes a cervical-traction group, a high-pull-to-upper-molar group, a modified-activator group, and an untreated Class II control group. Using newly developed computer-conducted procedures, which are described, we have been able to partition the orthodontic and orthopedic components of upper molar displacement and also to isolate treatment effects from those attributable to spontaneous growth and development. In the region of ANS, small but statistically significant and clinically meaningful differences were noted between treatments. When the intercurrent effects of growth and development had been factored out (Table III), orthopedic distal displacement of ANS was significantly greater in the high-pull and cervical groups than in the activator group. Orthopedic downward displacement of ANS was seen to be significantly greater in the cervical group than in the high-pull and activator groups. In the region of the first molar cusp, mean distal displacement of the tooth as an orthopedic effect was found to be almost identical in the cervical and high-pull groups (although variability was greater in the cervical group), but the mean orthodontic effect was significantly greater in the high-pull group than in the cervical group. In the cervical group, where relatively light forces were used for relatively long treatment periods on average, more of the total distal displacement of the upper molar was of an orthopedic character than of an orthodontic character. Conversely, in the high-pull group, in which relatively heavier forces tended to be used for briefer treatment periods, most of the distal

  6. Device for lengthening of a musculotendinous unit by direct continuous traction in the sheep

    Directory of Open Access Journals (Sweden)

    Zumstein Matthias A

    2012-05-01

    Full Text Available Abstract Background Retraction, atrophy and fatty infiltration are signs subsequent to chronic rotator cuff tendon tears. They are associated with an increased pennation angle and a shortening of the muscle fibers in series. These deleterious changes of the muscular architecture are not reversible with current repair techniques and are the main factors for failed rotator cuff tendon repair. Whereas fast stretching of the retracted musculotendinous unit results in proliferation of non-contractile fibrous tissue, slow stretching may lead to muscle regeneration in terms of sarcomerogenesis. To slowly stretch the retracted musculotendinous unit in a sheep model, two here described tensioning devices have been developed and mounted on the scapular spine of the sheep using an expandable threaded rod, which has been interposed between the retracted tendon end and the original insertion site at the humeral head. Traction is transmitted in line with the musculotendinous unit by sutures knotted on the expandable threaded rod. The threaded rod of the tensioner is driven within the body through a rotating axis, which enters the body on the opposite side. The tendon end, which was previously released (16 weeks prior from its insertion site with a bone chip, was elongated with a velocity of 1 mm/day. Results After several steps of technical improvements, the tensioner proved to be capable of actively stretching the retracted and degenerated muscle back to the original length and to withstand the external forces acting on it. Conclusion This technical report describes the experimental technique for continuous elongation of the musculotendinous unit and reversion of the length of chronically shortened muscle.

  7. The structure of cell-matrix adhesions: the new frontier.

    Science.gov (United States)

    Hanein, Dorit; Horwitz, Alan Rick

    2012-02-01

    Adhesions between the cell and the extracellular matrix (ECM) are mechanosensitive multi-protein assemblies that transmit force across the cell membrane and regulate biochemical signals in response to the chemical and mechanical environment. These combined functions in force transduction, signaling and mechanosensing contribute to cellular phenotypes that span development, homeostasis and disease. These adhesions form, mature and disassemble in response to actin organization and physical forces that originate from endogenous myosin activity or external forces by the extracellular matrix. Despite advances in our understanding of the protein composition, interactions and regulation, our understanding of matrix adhesion structure and organization, how forces affect this organization, and how these changes dictate specific signaling events is limited. Insights across multiple structural levels are acutely needed to elucidate adhesion structure and ultimately the molecular basis of signaling and mechanotransduction. Here we describe the challenges and recent advances and prospects for unraveling the structure of cell-matrix adhesions and their response to force. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Optical adhesive property study

    Energy Technology Data Exchange (ETDEWEB)

    Sundvold, P.D.

    1996-01-01

    Tests were performed to characterize the mechanical and thermal properties of selected optical adhesives to identify the most likely candidate which could survive the operating environment of the Direct Optical Initiation (DOI) program. The DOI system consists of a high power laser and an optical module used to split the beam into a number of channels to initiate the system. The DOI requirements are for a high shock environment which current military optical systems do not operate. Five candidate adhesives were selected and evaluated using standardized test methods to determine the adhesives` physical properties. EC2216, manufactured by 3M, was selected as the baseline candidate adhesive based on the test results of the physical properties.

  9. Solid-state transformer-based new traction drive system and control

    Science.gov (United States)

    Feng, Jianghua; Shang, Jing; Zhang, Zhixue; Liu, Huadong; Huang, Zihao

    2017-11-01

    A new type of traction drive system consisting of solid-state traction transformer (SSTT), inverter unit, auxiliary inverter, traction motor and other key components is built in order to suit the demand of developing the next-generation electric traction system which will be efficient and lightweight, with high power density. For the purpose of reducing system volume and weight and improving efficiency and grid-side power quality, an efficient SSTT optimized topology combining high-voltage cascaded rectifiers with high-power high-frequency LLC resonant converter is proposed. On this basis, an integrated control strategy built upon synchronous rotating reference frame is presented to achieve unified control over fundamental active, reactive and harmonic components. The carrier-interleaving phase shift modulation strategy is proposed to improve the harmonic performance of cascaded rectifiers. In view of the secondary pulsating existing in a single-phase system, the mathematical model of secondary power transfer is built, and the mechanism of pulsating voltage resulting in beat frequency of LLC resonant converter is revealed, so as to design optimum matching of system parameters. Simulation and experimental results have verified that the traction system and control scheme mentioned in this paper are reasonable and superior and that they meet the future application requirements for rail transit.

  10. The aspect of vector control using the asynchronous traction motor in locomotives

    Directory of Open Access Journals (Sweden)

    L. Liudvinavičius

    2009-12-01

    Full Text Available The article examines curves controlling asynchronous traction motors increasingly used in locomotive electric drives the main task of which is to create a tractive effort-speed curve of an ideal locomotive Fk = f(v, including a hyperbolic area the curve of which will create conditions showing that energy created by the diesel engine of diesel locomotives (electric locomotives and in case of electric trains, electricity taken from the contact network over the entire range of locomotive speed is turned into efficient work. Mechanical power on wheel sets is constant Pk = Fkv = const, the power of the diesel engine is fully used over the entire range of locomotive speed. Tractive effort-speed curve Fk(v shows the dependency of locomotive traction power Fk on movement speed v. The article presents theoretical and practical aspects relevant to creating the structure of locomotive electric drive and selecting optimal control that is especially relevant to creating the structure of locomotive electric drive using ATM (asynchronous traction motor that gains special popularity in traction rolling stock replacing DC traction motors having low reliability. The frequency modes of asynchronous motor speed regulation are examined. To control ATM, the authors suggest the method of vector control presenting the structural schemes of a locomotive with ATM and control algorithm.

  11. Bioinspired pressure actuated adhesive system

    NARCIS (Netherlands)

    Paretkar, D.R.; Kamperman, M.M.G.; Schneider, A.S.; Martina, D.; Creton, C.; Arzt, E.

    2011-01-01

    We developed a dry synthetic adhesive system inspired by gecko feet adhesion that can switch reversibly from adhesion to non-adhesion with applied pressure as external stimulus. Micropatterned polydimethylsiloxane (PDMS) surfaces with pillars of 30 µm length and 10 µm diameter were fabricated using

  12. Many Roles of Wood Adhesives

    Science.gov (United States)

    Charles R. Frihart

    2014-01-01

    Although wood bonding is one of the oldest applications of adhesives, going back to early recorded history (1), some aspects of wood bonds are still not fully understood. Most books in the general area of adhesives and adhesion do not cover wood bonding. However, a clearer understanding of wood bonding and wood adhesives can lead to improved products. This is important...

  13. Cohesion and Adhesion with Proteins

    Science.gov (United States)

    Charles R. Frihart

    2016-01-01

    With increasing interest in bio-based adhesives, research on proteins has expanded because historically they have been used by both nature and humans as adhesives. A wide variety of proteins have been used as wood adhesives. Ancient Egyptians most likely used collagens tobond veneer to wood furniture, then came casein (milk), blood, fish scales, and soy adhesives, with...

  14. Cellular contractility and substrate elasticity: a numerical investigation of the actin cytoskeleton and cell adhesion.

    Science.gov (United States)

    Ronan, William; Deshpande, Vikram S; McMeeking, Robert M; McGarry, J Patrick

    2014-04-01

    Numerous experimental studies have established that cells can sense the stiffness of underlying substrates and have quantified the effect of substrate stiffness on stress fibre formation, focal adhesion area, cell traction, and cell shape. In order to capture such behaviour, the current study couples a mixed mode thermodynamic and mechanical framework that predicts focal adhesion formation and growth with a material model that predicts stress fibre formation, contractility, and dissociation in a fully 3D implementation. Simulations reveal that SF contractility plays a critical role in the substrate-dependent response of cells. Compliant substrates do not provide sufficient tension for stress fibre persistence, causing dissociation of stress fibres and lower focal adhesion formation. In contrast, cells on stiffer substrates are predicted to contain large amounts of dominant stress fibres. Different levels of cellular contractility representative of different cell phenotypes are found to alter the range of substrate stiffness that cause the most significant changes in stress fibre and focal adhesion formation. Furthermore, stress fibre and focal adhesion formation evolve as a cell spreads on a substrate and leading to the formation of bands of fibres leading from the cell periphery over the nucleus. Inhibiting the formation of FAs during cell spreading is found to limit stress fibre formation. The predictions of this mutually dependent material-interface framework are strongly supported by experimental observations of cells adhered to elastic substrates and offer insight into the inter-dependent biomechanical processes regulating stress fibre and focal adhesion formation.

  15. Effects of traction on the blood circulation of femoral head: DSA study on a canine model

    International Nuclear Information System (INIS)

    Yang Xiujun; Xiao Jian; Ren Qile; Fu Shiping; Li Wei; Xiao Xiangsheng

    2010-01-01

    Objective: To study the influence of traction on the blood circulation of femur head and its evaluation by DSA. Methods: Using micro-catheter, transfemoral selective femoral circumflex arteriography in 22 healthy dogs was performed in unilateral hip before (Group A, n=22) and immediately (Group B, n=22), 30 (Group D, n=22), 60 (Group E, n=20), 90 (Group F, n=10), 120 (Group G, n= 10) minutes during 2 kg skin hip traction, and immediately after traction removal (Group H, I, J, L and O) , and 30 minutes after traction removal with 60, 90 and 120 minutes continuous traction (Group K, M and P) , and 60 minutes after traction removal with 90 and 120 minutes continuous traction (Group N and Q). DSA was also performed immediately during 4 kg weight traction before continuous traction in 12 hips (Group C). Blood circulation of the femoral head was evaluated mainly by observing its perfusion and time of circulation. Femur head perfusion was assessed as good scoring 3, poor scoring 2 and extremely poor scoring 1. Femur head circulation time was assessed as normal scoring 3, prolonged scoring 2 and remarkably prolonged scoring 1. Analysis of variance was employed for analysis of the angiographic findings between different groups. Results: Good femoral head perfusion in Group A to Q was 22, 0, 0, 0, 0, 0, 0, 22, 22, 1, 18, 0, 0, 8, 0, 0 and 1 hips respectively, poor one was 0, 22, 8, 22, 15, 4, 1, 0, 0, 15, 2, 4, 6, 2, 1, 3 and 8 hips, respectively, extremely poor one was 0, 0, 4, 0, 5, 6, 9, 0, 0, 4, 0, 6, 4, 0, 9, 7 and 1 hips, respectively; and normal femoral head blood circulation time was 22, 0, 0, 0, 0, 0, 0, 22, 22, 1, 18, 0, 0, 8, 0, 0 and 1 hips, respectively, prolonged one was 0, 22, 9, 22, 15, 4, 2, 0, 0, 15, 2, 5, 7, 2, 2, 4 and 8 hips, respectively, remarkably prolonged one was 0, 0, 3, 0, 5, 6, 8, 0, 0, 4, 0, 5, 3, 0, 8, 6 and 1 hips, respectively. F value of femoral head perfusion among group A and B,group B and C, group B, D, E, F and G, Group H, I, J, L and O

  16. Traction endurance biomechanical study of metallic suture anchors at different insertion angles

    Directory of Open Access Journals (Sweden)

    Azato Flávia Namie

    2003-01-01

    Full Text Available The suture anchors' insertion angle and its traction resistance are the main subjects of this study. Twenty trials were realized using threaded suture anchors in four diferents angulations (30º /45º /60º /90º in human bone (distal femur and another twenty trials in artificial bone (SawboneTM. The anchors were pulled out being tractioned uprightly from its bone surface by a Kratos Universal test machine. The human bone results found no relation between the main subjects of this study, so whithout statistical value. On the other hand at the artificial bone the insertion angle of 90º beared more traction, being statistically significant compared to the other angles.

  17. [The application of delayed skin grafting combined traction in severe joint cicatricial contracture].

    Science.gov (United States)

    Xu, Zihan; Zhang, Zhenxin; Wang, Benfeng; Sun, Yaowen; Guo, Yadong; Gao, Wenjie; Qin, Gaoping

    2014-11-01

    To investigate the effect of delayed skin grafting combined traction in severe joint cicatricial contracture. At the first stage, the joint cicatricial contracture was released completely with protection of vessels, nerves and tendons. The wound was covered with allogenetic skin or biomaterials. After skin traction for 7-14 days, the joint could reach the extension position. Then the skin graft was performed on the wound. 25 cases were treated from Mar. 2000 to May. 2013. Primary healing was achieved at the second stage in all the cases. The skin graft had a satisfactory color and elasticity. Joint function was normal. All the patients were followed up for 3 months to 11 years with no hypertrophic scar and contraction relapse, except for one case who didn' t have enough active exercise on shoulder joint. Delayed skin grafting combined traction can effectively increase the skin graft survival rate and improve the joint function recovery.

  18. An overview of the development of lead/acid traction batteries for electric vehicles in India

    Science.gov (United States)

    Sivaramaiah, G.; Subramanian, V. R.

    Electric vehicles (EVs) made an entry into the Indian scene quite recently in the area of passenger transportation, milk floats and other similar applications. The industrial EV market, with various models of fork-lift trucks and platform trucks already in wide use all over India, is a better understood application of EV batteries. The lead/acid traction batteries available in India are not of high-energy density. The best available indigenous lead/acid traction battery has an energy density ( C/5 rate) of 30 W h kg -1 as against 39 W h kg -1 available abroad. This paper reviews the developmental efforts relating to lead/acid traction batteries for electric vehicle applications in India, such as prototype road vehicles, commercial vehicles, rail cars, and locomotives. Due to the need for environmental protection and recognition of exhaustible, finite supplies of petroleum fuel, the Indian government is presently taking active interest in EV projects.

  19. Ulnar nerve injury due to lateral traction device during shoulder arthroscopy: Was it avoidable?

    Directory of Open Access Journals (Sweden)

    Vivek Pandey

    2017-01-01

    Full Text Available Most of the nerve injuries reported during shoulder arthroscopy in a beach chair, or lateral position is related to inappropriate patient positioning or excess traction. The lateral decubitus position is more vulnerable for traction-related neuropraxia. The present case serves as an important lesson from an avoidable situation of “having a one track mind” of the surgical team during the arthroscopic repair of shoulder instability performed in the lateral decubitus position. The operating surgeon must supervise the appropriate positioning of the patient on operation table and adequate padding of vulnerable bony points before beginning of shoulder arthroscopy to prevent any position-related nerve injuries. This is probably the first case to illustrate an unusual cause of ulnar nerve compression particularly related to the use of an additional traction device in the arthroscopic repair of shoulder instability performed in lateral decubitus position, which has not been previously defined.

  20. Experimental research of vehicle traction properties for reconstruction of traffic accidents

    Directory of Open Access Journals (Sweden)

    Dudziak Marian

    2018-01-01

    Full Text Available In order to broaden the database of motor vehicle traction properties in unusual conditions, the research team has performed experimental studies: on wet and snow-covered surfaces. Tests of vehicles equipped with winter tyres with non-skid snow chains have been performed on snow-covered surfaces. It has been shown that on snowy surface chains affect vehicle traction properties, mostly during acceleration. They increase the rate of acceleration up to 50% compared to a vehicle with winter tyres without chains. The results of the performed research can be the basis for the full reconstruction of road accidents under these conditions. Knowledge of traction properties of cars in difficult and unusual conditions is an important cognitive factor and serves to improve road safety.

  1. Severe Postoperative Complications may be Related to Mesenteric Traction Syndrome during Open Esophagectomy

    DEFF Research Database (Denmark)

    Ambrus, R; Svendsen, L B; Secher, N H

    2017-01-01

    . RESULTS: Flushing appeared in 17 (open) and 5 (robotically assisted) surgical cases ( p = 0.001). Mean arterial pressure was stable during both types of surgeries, but infusion of vasopressors during the first hour of open surgery was related to development of widespread (Grade II) flushing ( p = 0......BACKGROUND: During abdominal surgery, traction of the mesenterium provokes mesenteric traction syndrome, including hypotension, tachycardia, and flushing, along with an increase in plasma prostacyclin (PGI2). We evaluated whether postoperative complications are related to mesenteric traction...... syndrome during esophagectomy. METHODS: Flushing, hemodynamic variables, and plasma 6-keto-PGF1α were recorded during the abdominal part of open ( n = 25) and robotically assisted ( n = 25) esophagectomy. Postoperative complications were also registered, according to the Clavien-Dindo classification...

  2. Halo-gravity traction in the treatment of severe spinal deformity: a systematic review and meta-analysis.

    Science.gov (United States)

    Yang, Changsheng; Wang, Huafeng; Zheng, Zhaomin; Zhang, Zhongmin; Wang, Jianru; Liu, Hui; Kim, Yongjung Jay; Cho, Samuel

    2017-07-01

    Halo-gravity traction has been reported to successfully assist in managing severe spinal deformity. This is a systematic review of all studies on halo-gravity traction in the treatment of spinal deformity to provide information for clinical practice. A comprehensive search was conducted for articles on halo-gravity traction in the treatment of spinal deformity according to the PRISMA guidelines. Appropriate studies would be included and analyzed. Preoperative correction rate of spinal deformity, change of pulmonary function and prevalence of complications were the main measurements. Sixteen studies, a total of 351 patients, were included in this review. Generally, the initial Cobb angle was 101.1° in the coronal plane and 80.5° in the sagittal plane, and it was corrected to 49.4° and 56.0° after final spinal fusion. The preoperative correction due to traction alone was 24.1 and 19.3%, respectively. With traction, the flexibility improved 6.1% but postoperatively the patients did not have better correction. Less aggressive procedures and improved pulmonary function were observed in patients with traction. The prevalence of traction-related complications was 22% and three cases of neurologic complication related to traction were noted. The prevalence of total complications related to surgery was 32% and that of neurologic complications was 1%. Partial correction could be achieved preoperatively with halo-gravity traction, and it may help decrease aggressive procedures, improve preoperative pulmonary function, and reduce neurologic complications. However, traction could not increase preoperative flexibility or final correction. Traction-related complications, although usually not severe, were not rare.

  3. From the Cover: Evidence for van der Waals adhesion in gecko setae

    Science.gov (United States)

    Autumn, Kellar; Sitti, Metin; Liang, Yiching A.; Peattie, Anne M.; Hansen, Wendy R.; Sponberg, Simon; Kenny, Thomas W.; Fearing, Ronald; Israelachvili, Jacob N.; Full, Robert J.

    2002-09-01

    Geckos have evolved one of the most versatile and effective adhesives known. The mechanism of dry adhesion in the millions of setae on the toes of geckos has been the focus of scientific study for over a century. We provide the first direct experimental evidence for dry adhesion of gecko setae by van der Waals forces, and reject the use of mechanisms relying on high surface polarity, including capillary adhesion. The toes of live Tokay geckos were highly hydrophobic, and adhered equally well to strongly hydrophobic and strongly hydrophilic, polarizable surfaces. Adhesion of a single isolated gecko seta was equally effective on the hydrophobic and hydrophilic surfaces of a microelectro-mechanical systems force sensor. A van der Waals mechanism implies that the remarkable adhesive properties of gecko setae are merely a result of the size and shape of the tips, and are not strongly affected by surface chemistry. Theory predicts greater adhesive forces simply from subdividing setae to increase surface density, and suggests a possible design principle underlying the repeated, convergent evolution of dry adhesive microstructures in gecko, anoles, skinks, and insects. Estimates using a standard adhesion model and our measured forces come remarkably close to predicting the tip size of Tokay gecko seta. We verified the dependence on size and not surface type by using physical models of setal tips nanofabricated from two different materials. Both artificial setal tips stuck as predicted and provide a path to manufacturing the first dry, adhesive microstructures.

  4. Asperity interaction in adhesive contact of metallic rough surfaces

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    The analysis of adhesive contact of metallic rough surfaces considering the effect of asperity interaction is the subject of this investigation. The micro-contact model of asperity interactions developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64) is combined with the elastic plastic adhesive contact model developed by Chang et al (1988 Trans. ASME: J. Tribol. 110 50-6) to consider the asperity interaction and elastic-plastic deformation in the presence of surface forces simultaneously. The well-established elastic adhesion index and plasticity index are used to consider the different contact conditions. Results show that asperity interaction influences the load-separation behaviour in elastic-plastic adhesive contact of metallic rough surfaces significantly and, in general, adhesion is reduced due to asperity interactions

  5. Polymer powder adhesion to metallic surface improvement with plasma

    International Nuclear Information System (INIS)

    Hladik, J.; Pichal, J.; Spatenka, P.; Pichal, J.; Spatenka, P.

    2008-01-01

    Useful method for corrosion prevention is coating of a base material with a suitable substance. It performs a barrier between the base material and its environment. Great attractions in this field have found polymers, among them polyethylenes (PE). Due to the low adhesion grade of unmodified polymer powder or granules the application of any modification process increasing the adhesion grade is crucial. At present there is no universal approach to polymer adhesion improvement and there have been employed various quite different techniques. Our research employed the PE adhesion improvement by plasma modification. There were used two plasma reactors - the microwave low pressure reactor and the atmospheric reactor employing dielectric barrier discharge (DBD). The adhesion of the powder was determined by measurement of strength force demanded for displacement of the PE-metal joint

  6. The geometric clutch at 20: stripping gears or gaining traction?

    Science.gov (United States)

    Lindemann, Charles B; Lesich, Kathleen A

    2015-08-01

    It has been 20 years since the geometric clutch (GC) hypothesis was first proposed. The core principle of the GC mechanism is fairly simple. When the axoneme of a eukaryotic flagellum is bent, mechanical stress generates forces transverse to the outer doublets (t-forces). These t-forces can push doublets closer together or pry them apart. The GC hypothesis asserts that changes in the inter-doublet spacing caused by t-forces are responsible for the activation and deactivation of the dynein motors, that creates the beat cycle. A series of computer models utilizing the clutch mechanism has shown that it can simulate ciliary and flagellar beating. The objective of the present review is to assess where things stand with the GC hypothesis in the clarifying light of new information. There is considerable new evidence to support the hypothesis. However, it is also clear that it is necessary to modify some of the original conceptions of the hypothesis so that it can be consistent with the results of recent experimental and ultrastructural studies. In particular, dynein deactivation by t-forces must be able to occur with dyneins that remain attached to the B-subtubule of the adjacent doublet. © 2015 Society for Reproduction and Fertility.

  7. Role of seta angle and flexibility in the gecko adhesion mechanism

    Science.gov (United States)

    Hu, Congcong; Alex Greaney, P.

    2014-08-01

    A model is developed to describe the reversible nature of gecko dry adhesion. The central aspect of this model is that the seta can be easily peeled away from the contacting surface by a small moment at the contact tip. It is shown that this contact condition is very sensitive, but can result in robust adhesion if individual setae are canted and highly flexible. In analogy to the "cone of friction," we consider the "adhesion region"—the domain of normal and tangential forces that maintain adhesion. Results demonstrate that this adhesion region is highly asymmetric enabling the gecko to adhere under a variety of loading conditions associated with scuttling horizontally, vertically, and inverted. Moreover, under each of these conditions, there is a low energy path to de-adhesion. In this model, obliquely canted seta (as possessed by geckos) rather than vertically aligned fibers (common in synthetic dry adhesive) provides the most robust adhesion.

  8. Comparison of the environmental performance of light mechanization and animal traction using a modular LCA approach

    DEFF Research Database (Denmark)

    Cerutti, Alessandro K.; Calvo, Angela; Bruun, Sander

    2014-01-01

    Animal traction has supported humans in most field operations since the origin of agriculture. With the introduction of mechanization, humans gained access to much more work power at similar management costs and were able to significantly increase the productivity and time efficiency of field...... Italy, while use of machine traction was evaluated using field data on two-wheel tractors performing the operations in similar production systems, converted to the specific functional unit. Owing to the differing properties of mechanical and living systems, it was difficult to establish a reliable...

  9. Simulation of Trolleybus Traction Induction Drive With Supercapacitor Energy Storage System

    Science.gov (United States)

    Brazis, V.; Latkovskis, L.; Grigans, L.

    2010-01-01

    The article considers the possibilities of saving the regenerative braking energy in Škoda 24Tr type trolleybuses by installing the onboard supercapacitor energy storage system (ESS) and improving its performance with automated switching to the autonomous traction mode. Proposed is an ESS control system with constant DC bus voltage in the supercapacitor charging mode and supercapacitor current proportional to the AC drive current in the discharging mode. The authors investigate stability of the trolleybus ESS control system operating together with AC traction drive in various overhead voltage failure modes. The co-simulation of ESS operation was done by Matlab/Simulink AC drive and PSIM ESS continuous models.

  10. Parametric tests of a traction drive retrofitted to an automotive gas turbine

    Science.gov (United States)

    Rohn, D. A.; Lowenthal, S. H.; Anderson, N. E.

    1980-01-01

    The results of a test program to retrofit a high performance fixed ratio Nasvytis Multiroller Traction Drive in place of a helical gear set to a gas turbine engine are presented. Parametric tests up to a maximum engine power turbine speed of 45,500 rpm and to a power level of 11 kW were conducted. Comparisons were made to similar drives that were parametrically tested on a back-to-back test stand. The drive showed good compatibility with the gas turbine engine. Specific fuel consumption of the engine with the traction drive speed reducer installed was comparable to the original helical gearset equipped engine.

  11. Multiroller traction drive speed reducer: Evaluation for automotive gas turbine engine

    Science.gov (United States)

    Rohn, D. A.; Anderson, N. E.; Loewenthal, S. H.

    1982-01-01

    Tests were conducted on a nominal 14:1 fixed-ratio Nasvytis multiroller traction drive retrofitted as the speed reducer in an automotive gas turbine engine. Power turbine speeds of 45,000 rpm and a drive output power of 102 kW (137 hp) were reached. The drive operated under both variable roller loading (proportional to torque) and fixed roller loading (automatic loading mechanism locked). The drive operated smoothly and efficiently as the engine speed reducer. Engine specific fuel consumption with the traction speed reducer was comparable to that with the original helical gearset.

  12. Peel testing behavior of mushroom-top terminated structured adhesives

    Science.gov (United States)

    Hossfeld, Craig Kenneth

    Synthetic structured surfaces have been created based on the extraordinary adhesive ability exhibited by insects, spiders, and geckos. The adhesion of synthetic and natural structured adhesives is attributed to the cumulative addition of van der Waals forces acting on the structures of the surface. It has been shown that for synthetic surfaces a "mushroom top" or "flanged" terminating structure exhibits the highest adhesion. Unfortunately, due to the variety of testing and fabrication techniques and the small scale of previous studies, the detachment behavior of these structures is not well understood. This research systematically investigated the effect of peel angle, pillar diameter, flange diameter, and pillar aspect ratio on the force required for peeling. Explicit emphasis was placed on relatively large pillar structures to allow for in situ optical visualization in order to gain insights into fundamental mechanisms which dictate peeling. Traditional molding techniques were used to fabricate optical-scale mushroom terminated structures with pillar diameters of 1mm and 400microm and aspect ratios of 1, 3, and 5. Results were quantitatively compared to peel testing theory for conventional adhesives. It was convincingly demonstrated that the adhesive energy of a patterned surface changes as function of angle, and cannot be treated as a constant. The variability in the energy was linked to mechanistic differences in detachment through in situ observations and finite element analysis. Experimental results show that smaller pillars do not necessarily lead to higher adhesion during peeling, aspect ratio plays little role in peeling adhesive behavior, and pillar flange size is critical to adhesion. The conclusions from this study outline design parameters for mushroom topped dry adhesives in peeling applications.

  13. ONCE AGAIN ABOUT DETERMINATION OF SAVING OF ENERGY FOR TRACTION DUE TO PARTIAL CUT–OFF OF TRACTION ENGINES OF ELECTRIC ROLLING STOCK

    Directory of Open Access Journals (Sweden)

    G. K. Getman

    2013-09-01

    Full Text Available Purpose. In general the well known methods for determination of energy saving due to the partial traction engines cut-off based on their comparison to efficiency coefficient or to the power of energy losses do not allow objective estimation of efficiency of these measures and in a number of cases result in erroneous results and errors. The search for new more advanced methods for determination of energy saving at the partial cut-off of the traction engines is needed. Methodology. The method of calculation determination of energy saving when partial cutting-off of the traction engines is offered. It is based on the use of rationality coefficient as the loading mode of the electric power consumption for the measuring instrument of transportation activity. Findings. Using the given mathematical expressions it is possible to determine the energy saving in both the relative and absolute values and set the terms (motion speed and route gradient, under which the energy saving will take place. Originality. The method of the task solving, which is based on the evaluation of energy consumption differences for the compared variants (not on the comparison of efficiency coefficient or differences of power of energy losses is offered. Practical value. The given methodology allows obtaining more exact conclusions in relation to the electric power consumption, as the comparison of energy losses power or the efficiency coefficient does not determine precisely the electric power consumption for traction. Therefore the conclusions based on the comparison of power of energy losses or efficiency coefficient can appear inexact.

  14. Single cell adhesion assay using computer controlled micropipette.

    Directory of Open Access Journals (Sweden)

    Rita Salánki

    Full Text Available Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today's techniques typically have an extremely low throughput (5-10 cells per day. Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min. We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a

  15. Systemic design of synchronous traction drives for large speed-range electric vehicle; Conception systemique de chaines de traction synchrones pour vehicule electrique a large gamme de vitesse

    Energy Technology Data Exchange (ETDEWEB)

    Randi, S.A.

    2003-04-15

    The presented study deals with a systemic approach based design of permanent magnet brush-less actuators. The considered system is the electric vehicle motorized with this actuator on a large speed range. First, the review of vehicles architectures and general specifications put emphasis on the design problem complexity and the interest of a simultaneous design taking account of the whole traction chain driving cycle. Then the IPM plane and lumped parameter models are used to bring out the variables which characterizes the work beyond the base speed and the ability in flux weakening operation. The properties of machines with two rotor parts in such operation are studied. The new degrees of freedom available with these structures bring new solutions for drives with larger speed range. Then a model taking account each subsystem is presented and implemented in a global SABER simulator, involving sizing models of components. This tool enables to study the work of the traction chain over significant driving cycles and the performances evaluation. A last, this simulator is brought into work so as to perform a simultaneous design of the traction chain components as battery, inverter, machine, gear, thanks to an optimisation procedure based on genetic algorithm able to process continuous sizes variations and structure modifications, considering performance criteria on losses and cost. (author)

  16. Elucidating How Wood Adhesives Bond to Wood Cell Walls using High-Resolution Solution-State NMR Spectroscopy

    Science.gov (United States)

    Daniel J. Yelle

    2013-01-01

    Some extensively used wood adhesives, such as pMDI (polymeric methylene diphenyl diisocyanate) and PF (phenol formaldehyde) have shown excellent adhesion properties with wood. However, distinguishing whether the strength is due to physical bonds (i.e., van der Waals, London, or hydrogen bond forces) or covalent bonds between the adherend and the adhesive is not fully...

  17. Traction and lubricant film temperature as related to the glass transition temperature and solidification. [using infrared spectroscopy on EHD contacts

    Science.gov (United States)

    Lauer, J. L.; Peterkin, M. E.

    1978-01-01

    Does a traction fluid have to be a glass or solid under operating conditions. Infrared spectra on dynamic EHD contacts of several types of fluid were used to determine the surface and oil-film temperatures. Polarized spectral runs were made to study molecular alignment. Static glass transition pressures at appropriate temperatures were between 0.1 and 2.0 GPa, with the traction fluid showing the highest. In the EHD contact region, the traction fluid showed both the highest film temperatures as well as the greatest degree of molecular alignment. A plot of the difference between the film and surface temperatures vs shear rate resulted in a master plot valid for all the fluids. From this work, the authors propose a model of 'fluid' traction, where friction between parallel rough molecules provides the traction.

  18. Electrically Conductive Epoxy Adhesives

    Directory of Open Access Journals (Sweden)

    Lan Bai

    2011-02-01

    Full Text Available Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. The effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured adhesive matrix viscosity on the electrical conduction behavior of epoxy-based adhesives are presented in this work. For this purpose, epoxy-based adhesives were prepared using conductive fillers of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 μm in diameter, and 160 or 260 μm in length. HCl and H3PO4 acid solutions were used to etch and remove the surface oxide layers from the fillers. The plane resistance of filled adhesive films was measured using the four-point method. In all cases of conductive filler addition, the planar resistivity levels for the composite adhesive films increased when the film thickness was reduced. The shape of resistivity-thickness curves was negative exponential decaying type and was modeled using a mathematical relation. The relationships between the conductive film resistivities and the filler volume fractions were also derived mathematically based on the experimental data. Thus, the effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity could be included empirically by using these mathematical relations based on the experimental data. By utilizing the relations we proposed to model thickness-dependent and volume fraction-dependent conduction behaviors separately, we were able to describe the combined and coupled volume fraction-film thickness relationship mathematically based on our experimental data.

  19. The electron beam cure of epoxy paste adhesives

    International Nuclear Information System (INIS)

    Farmer, J.D.; Janke, C.J.; Lopata, V.J.

    1998-01-01

    Recently developed epoxy paste adhesives were electron beam cured and experimentally explored to determine their suitability for use in an aerospace-quality aircraft component. There were two major goals for this program. The first was to determine whether the electron beam-curable past adhesives were capable of meeting the requirements of the US Air Force T-38 supersonic jet trainer composite windshield frame. The T-38 windshield frame's arch is currently manufactured by bonding thin stainless steel plies using an aerospace-grade thermally-cured epoxy film adhesive. The second goal was to develop the lowest cost hand layup and debulk process that could be used to produce laminated steel plies with acceptable properties. The laminate properties examined to determine adhesive suitability include laminate mechanical and physical properties at room, adhesive tack, out-time capability, and the debulk requirements needed to achieve these properties. Eighteen past adhesives and four scrim cloths were experimentally examined using this criteria. One paste adhesive was found to have suitable characteristics in each of these categories and was later chosen for the manufacture of the T-38 windshield frame. This experimental study shows that by using low-cost debulk and layup processes, the electron beam-cured past adhesive mechanical and physical properties meet the specifications of the T-38 composite windshield frame

  20. BACKGROUNDS OF EXPERIMENTAL INVESTIGATION OF ELECTROMAGNETIC COMPATIBILITY OF TRACTION ASYNCHRONOUS ELECTRIC DRIVES IN THE STRUCTURE OF DC TRACTION POWER SUPPLY SYSTEM

    Directory of Open Access Journals (Sweden)

    YU. S. Bondarenko

    2014-04-01

    Full Text Available Purpose. Application of physical modeling as a tool for research of any events or systems is becoming more widespread, including the field of railway transport. At the same time the adequacy of results that can be obtained, depends largely on the similarity degree of the physical model to real system. From the standpoint of the traction asynchronous electric drive (TAED research together with the traction power supply system research, the similarity can not be determined by the direct proportion of the parameters, because the processes nature accompanying the operation of these systems is non-linear. These features should be taken into account in the experimental setup, the basis for constructing of which is establishing of the system similarity that defines the purpose of this paper. Methodology. At the heart of the experimental setup creation laid reproduction of processes of energy transformation in the system of the DC traction power supply. Determination of the similarity degree of the proposed facility to the real system was carried out using the basic theorems of the similarity theory, their additional provisions on the complexity and nonlinear systems, as well as elements of mathematical analysis. Findings. According to the results of work: 1 The block diagram, the energy conversion mechanism of which is similar to the real system was received. This scheme is the basis of experimental setup, built in the future for the study of electromagnetic compatibility of TAED in the structure of DC traction electric power supply system. 2 Similarity of obtained structural scheme with the real system with the mechanism definition of calculating the scaling relations was established. Originality. In the process of establishing the similarity a simplified method for determining the scaling relations for nonlinear systems was suggested. They are identical in their structure components, but have different capacities. Practical value. Experimental

  1. Long-lived force patterns and deformation waves at repulsive epithelial boundaries

    Science.gov (United States)

    Rodríguez-Franco, Pilar; Brugués, Agustí; Marín-Llauradó, Ariadna; Conte, Vito; Solanas, Guiomar; Batlle, Eduard; Fredberg, Jeffrey J.; Roca-Cusachs, Pere; Sunyer, Raimon; Trepat, Xavier

    2017-10-01

    For an organism to develop and maintain homeostasis, cell types with distinct functions must often be separated by physical boundaries. The formation and maintenance of such boundaries are commonly attributed to mechanisms restricted to the cells lining the boundary. Here we show that, besides these local subcellular mechanisms, the formation and maintenance of tissue boundaries involves long-lived, long-ranged mechanical events. Following contact between two epithelial monolayers expressing, respectively, EphB2 and its ligand ephrinB1, both monolayers exhibit oscillatory patterns of traction forces and intercellular stresses that tend to pull cell-matrix adhesions away from the boundary. With time, monolayers jam, accompanied by the emergence of deformation waves that propagate away from the boundary. This phenomenon is not specific to EphB2/ephrinB1 repulsion but is also present during the formation of boundaries with an inert interface and during fusion of homotypic epithelial layers. Our findings thus unveil a global physical mechanism that sustains tissue separation independently of the biochemical and mechanical features of the local tissue boundary.

  2. Switchable bio-inspired adhesives

    Science.gov (United States)

    Kroner, Elmar

    2015-03-01

    Geckos have astonishing climbing abilities. They can adhere to almost any surface and can run on walls and even stick to ceilings. The extraordinary adhesion performance is caused by a combination of a complex surface pattern on their toes and the biomechanics of its movement. These biological dry adhesives have been intensely investigated during recent years because of the unique combination of adhesive properties. They provide high adhesion, allow for easy detachment, can be removed residue-free, and have self-cleaning properties. Many aspects have been successfully mimicked, leading to artificial, bio-inspired, patterned dry adhesives, and were addressed and in some aspects they even outperform the adhesion capabilities of geckos. However, designing artificial patterned adhesion systems with switchable adhesion remains a big challenge; the gecko's adhesion system is based on a complex hierarchical surface structure and on advanced biomechanics, which are both difficult to mimic. In this paper, two approaches are presented to achieve switchable adhesion. The first approach is based on a patterned polydimethylsiloxane (PDMS) polymer, where adhesion can be switched on and off by applying a low and a high compressive preload. The switch in adhesion is caused by a reversible mechanical instability of the adhesive silicone structures. The second approach is based on a composite material consisting of a Nickel- Titanium (NiTi) shape memory alloy and a patterned adhesive PDMS layer. The NiTi alloy is trained to change its surface topography as a function of temperature, which results in a change of the contact area and of alignment of the adhesive pattern towards a substrate, leading to switchable adhesion. These examples show that the unique properties of bio-inspired adhesives can be greatly improved by new concepts such as mechanical instability or by the use of active materials which react to external stimuli.

  3. Design of salient pole PM synchronous machines for a vehicle traction application. Analysis and implementation

    Energy Technology Data Exchange (ETDEWEB)

    Rilla, M.

    2012-07-01

    This doctoral thesis presents a study on the development of a liquid-cooled frame salient pole permanent-magnet-exited traction machine for a four-wheel-driven electric car. The emphasis of the thesis is put on a radial flux machine design in order to achieve a light-weight machine structure for traction applications. The design features combine electromagnetic and thermal design methods, because traction machine operation does not have a strict operating point. Arbitrary load cycles and the flexible supply require special attention in the design process. It is shown that accurate modelling of the machine magnetic state is essential for high-performance operation. The saturation effect related to the cross-saturation has to be taken carefully into account in order to achieve the desired operation. Two prototype machines have been designed and built for testing: one totally enclosed machine with a special magnet module pole arrangement and another through-ventilated machine with a more traditional embedded magnet structure. Both structures are built with magnetically salient structures in order to increase the torque production capability with the reluctance torque component. Both machine structures show potential for traction usage. However, the traditional embedded magnet design turns out to be mechanically the more secure one of these two machine options. (orig.)

  4. Spatial discretization methods for air gap permeance calculations in double salient traction motors

    NARCIS (Netherlands)

    Ilhan, E.; Kremers, M.F.J.; Motoasca, T.E.; Paulides, J.J.H.; Lomonova, E.

    2012-01-01

    Weight limitations in electric/hybrid cars demand the highest possible power-to-weight ratio from the traction motor, as in double salient permanent magnet (PM) machines. Their high flux densities in the air gap result in nonlinear analytical models, which need to be time optimized. The incorporated

  5. Performance Availability Assessment of Combined Multi Power Source Traction Drive Considering Real Operational Conditions

    Directory of Open Access Journals (Sweden)

    Frenkel Ilia

    2016-09-01

    Full Text Available The present paper deals with the vehicle’s traction electric drive, consisting of several various electric power sources. One of the main requirements for such systems are the safety and sustainable operations, achieved largely the implementation of an uninterrupted supply of the vehicle’s propulsion system with an electric power.

  6. Wavelet Entropy-Based Traction Inverter Open Switch Fault Diagnosis in High-Speed Railways

    Directory of Open Access Journals (Sweden)

    Keting Hu

    2016-03-01

    Full Text Available In this paper, a diagnosis plan is proposed to settle the detection and isolation problem of open switch faults in high-speed railway traction system traction inverters. Five entropy forms are discussed and compared with the traditional fault detection methods, namely, discrete wavelet transform and discrete wavelet packet transform. The traditional fault detection methods cannot efficiently detect the open switch faults in traction inverters because of the low resolution or the sudden change of the current. The performances of Wavelet Packet Energy Shannon Entropy (WPESE, Wavelet Packet Energy Tsallis Entropy (WPETE with different non-extensive parameters, Wavelet Packet Energy Shannon Entropy with a specific sub-band (WPESE3,6, Empirical Mode Decomposition Shannon Entropy (EMDESE, and Empirical Mode Decomposition Tsallis Entropy (EMDETE with non-extensive parameters in detecting the open switch fault are evaluated by the evaluation parameter. Comparison experiments are carried out to select the best entropy form for the traction inverter open switch fault detection. In addition, the DC component is adopted to isolate the failure Isolated Gate Bipolar Transistor (IGBT. The simulation experiments show that the proposed plan can diagnose single and simultaneous open switch faults correctly and timely.

  7. Severe Postoperative Complications may be Related to Mesenteric Traction Syndrome during Open Esophagectomy.

    Science.gov (United States)

    Ambrus, R; Svendsen, L B; Secher, N H; Goetze, J P; Rünitz, K; Achiam, M P

    2017-09-01

    During abdominal surgery, traction of the mesenterium provokes mesenteric traction syndrome, including hypotension, tachycardia, and flushing, along with an increase in plasma prostacyclin (PGI 2 ). We evaluated whether postoperative complications are related to mesenteric traction syndrome during esophagectomy. Flushing, hemodynamic variables, and plasma 6-keto-PGF 1α were recorded during the abdominal part of open ( n = 25) and robotically assisted ( n = 25) esophagectomy. Postoperative complications were also registered, according to the Clavien-Dindo classification. Flushing appeared in 17 (open) and 5 (robotically assisted) surgical cases ( p = 0.001). Mean arterial pressure was stable during both types of surgeries, but infusion of vasopressors during the first hour of open surgery was related to development of widespread (Grade II) flushing ( p = 0.036). For patients who developed flushing, heart rate and plasma 6-keto-PGF 1α also increased ( p = 0.001 and p syndrome manifests more frequently during open than robotically assisted esophagectomy, and postoperative complications appear to be associated with severe mesenteric traction syndrome.

  8. Improving mandibular contour: A pilot study for indication of PPLA traction thread use.

    Science.gov (United States)

    Guida, Stefania; Persechino, Flavia; Rubino, Giuseppe; Pellacani, Giovanni; Farnetani, Francesca; Urtis, Giacomo Giovanni

    2018-02-20

    The request for less-aggressive procedures to improve mandibular contour is increasing. Several kinds of threads have been used for this purpose. Nevertheless, PLLA (poly-L-Lactic acid) traction thread procedure has not been previously described. To investigate the role of PLLA traction threads in improving mandibular contour. Twenty women were enrolled in the study. They were differentially classified for skin laxity. Patients were treated in a single session with two PLLA traction threads per side. Specific post-procedure instructions were given to patients, and complications occurred after the procedures were estimated. A Fisher's t-test was performed to identify criteria related to longevity of results. We found longevity of results to be associated with younger age (p = 0.001), absence of severe skin laxity of jawline and neck (p = 0.001), and aesthetic satisfaction (p = 0.024). Edema, swelling, and temporary skin contour irregularities were found in most cases (N = 16; 80%), whereas paresthesia resolving without sequelae in 2-4 weeks was found in two cases (10%). Our results show that selected patients, younger than 51 and showing a mild-moderate degree of skin laxity of jawline and neck angle represent ideal candidates for PLLA traction thread treatment. Further studies will be performed to confirm our results.

  9. Orthodontic Management with Traction and Asymmetric Extraction for Multiple Impacted Permanent Maxillary Teeth - A Case Report.

    Science.gov (United States)

    Niu, Qiannan; Zhang, Liang; Dai, Juan; Li, Feifei; Feng, Xue

    2016-01-01

    Multiple impacted teeth are a rare eruption disturbance that increases the case complexity. In this article, we described a 13-year-old boy whose 5 permanent maxillary teeth were not erupted although their root formation was complete. The orthodontic treatment with traction and asymmetric extraction was performed to achieve a significantly improved functional and esthetic result.

  10. Brushless traction PM Machines using commercial drive technology, part I: Design methodology and motor design

    NARCIS (Netherlands)

    Kazmin, Evgeny; Lomonova, E.A.; Paulides, J.J.H.

    2008-01-01

    A concept design approach for the brushless PM traction motor, which has crucial constraints on volume envelope and on the drive, is presented. The considered motor drive is the three-phase DC/AC converter, which is commercially available on the modern market of the standard variable frequency

  11. The determination of the pressure-viscosity coefficient of two traction oils using film thickness measurements

    NARCIS (Netherlands)

    Leeuwen, van H.J.

    2010-01-01

    The pressure-viscosity coefficients of two commercial traction fluids are determined by fitting calculation results on accurate film thickness measurements, obtained at a wide range of speeds, and different temperatures. Film thickness values are calculated using a numerical method and approximation

  12. Efficient start–up energy management via nonlinear control for eco–traction systems

    International Nuclear Information System (INIS)

    Becherif, M.; Ramadan, H.S.; Ayad, M.Y.; Hissel, D.; Desideri, U.; Antonelli, M.

    2017-01-01

    Highlights: • Renewable HPS for the train start-up within feeding durations. • Dynamic modelling of the modern HPS applied to traction systems. • Port-Controlled Hamiltonian (PCH) design for supercapacitors’ charge/discharge operation. • Experimental validation and applicability of HPSs for energy management in eco-tractions. - Abstract: Electrochemical capacitors, called supercapacitors (SCs) or ultracapacitors, are devices conveniently used for embedded electrical energy management owing to their huge capacitance, low internal resistance and flexible control through power electronic conversion. This paper proposes a main power supply of hybrid Wind Generator (WG)–SC within the train station for feeding the traction onboard SC through specified limited feeding transit durations. Onboard SCs provide the train with the requested start–up self–energy. The hybrid WG–SCs system is an environmental–friendly source that enables the independency on national grid and guarantees an efficient bidirectional power transfer for energy management with enhanced dynamic performance. Therefore, the dynamic modelling and the experimental analysis of the modern hybrid WG–SCs used for managing the charge/discharge operation of SCs at Unity Power Factor (UPF) mode are presented. For this purpose, the Port–Controlled Hamiltonian (PCH) methodology is deduced and explicitly presented. Simulation results, via MATLAB™, reveal that the proposed PCH control methodology can be successfully implemented to ensure acceptable system dynamic behavior. Numerical results are validated with experimental measurements to investigate the significance of the PCH approach for the energy management operation in eco-tractions.

  13. Original Paper Effects of oxen yoke and donkey collar on traction ...

    African Journals Online (AJOL)

    The realization of mechanized zaï with draft animal encounters the weakness of hitch traction capabilities. To overcome this issue, a study was conducted in three villages in the northern Burkina Faso with the aim at evaluating the effect of improved yoke and improved collar respectively with oxen and donkey harnessing on ...

  14. Defining Strong State Accountability Systems: How Can Better Standards Gain Greater Traction? A First Look

    Science.gov (United States)

    Reed, Eileen; Scull, Janie; Slicker, Gerilyn; Winkler, Amber M.

    2012-01-01

    Rigorous standards and aligned assessments are vital tools for boosting education outcomes but they have little traction without strong accountability systems that attach consequences to performance. In this pilot study, Eileen Reed, Janie Scull, Gerilyn Slicker, and Amber Winkler lay out the essential features of such accountability systems,…

  15. Skull traction for cervical spinal injury in Enugu: A 5‑year ...

    African Journals Online (AJOL)

    2015-11-05

    Nov 5, 2015 ... Background: Treatment of cervical spine injury is the most challenging of all the injuries of the spine, and there is yet no agreement on the best method of care. Objective: We studied the complications and outcome of two skull traction devices used to treat cases of cervical spine injury in three centers in ...

  16. Increase of energy efficiency of testing of traction electric machines of direct and pulsating current

    Directory of Open Access Journals (Sweden)

    A.M. Afanasov

    2015-03-01

    Full Text Available The results of the analysis of the effect of the load current of traction electric machines when tested for heating on the total electricity consumption for the test are presented. It is shown that increase of load current at the heating test permits to significantly reduce the consumption of electrical energy, and reduce the testing time without reducing its quality.

  17. The history of modern spinal traction with particular reference to neural disorders.

    Science.gov (United States)

    Shterenshis, M V

    1997-03-01

    The last 200 years of the history of spinal traction is described in the present article. The study starts at the end of the 18th century with the works of JA Venel (1789) who tried to apply the Hippocratic idea to modern surgery. Orthopedic specialists of the last century were mostly preoccupied with corsets and the method gained broader popularity when neurologists paid attention to the similar method of suspension. The Russian neurologist Osip Mochutkovsky described suspension as a method for the treatment of tabes dorsalis in an article published in the Russian magazine 'Vratch' in 1883. His works became known in Europe when JM Charcot paid attention to it and published a special short monograph on this subject in 1889. This work was translated into English (1889) and Russian (1890) and the method became popular in the treatment of tabes dorsalis and other neurological diseases. The eminent Russian neurologist VM Bekhterev proposed the combination of body suspension with cervical traction (1893). Some years later Gilles de la Tourette promoted the use of spinal traction in his neurological clinic (1897). Unfortunately neurologists worked without the cooperation of orthopedic specialists. During the first decades of the 20th century suspension was also replaced by traction in neurology. This method was used by both neurologists and orthopedic specialists but in the last decades neurologists lost their interests in it and it found greater use in traumatology and in spinal surgery where it is still in use today.

  18. Distributed Active Traction Control System Applied to the RoboCup Middle Size League

    Directory of Open Access Journals (Sweden)

    José Almeida

    2013-10-01

    Full Text Available This work addresses the problem of traction control in mobile wheeled robots in the particular case of the RoboCup Middle Size League (MSL. The slip control problem is formulated using simple friction models for ISePorto Team Robots with a differential wheel configuration. Traction was also characterized experimentally in the MSL scenario for relevant game events. This work proposes a hierarchical traction control architecture which relies on local slip detection and control at each wheel, with relevant information being relayed to a higher level responsible for global robot motion control. A dedicated one axis control embedded hardware subsystem allowing complex local control, high frequency current sensing and odometric information procession was developed. This local axis control board is integrated in a distributed system using CAN bus communications. The slipping observer was implemented in the axis control hardware nodes integrated in the ISePorto Robots and was used to control and detect loss of traction. An external vision system was used to perform a qualitative analysis of the slip detection and observer performance results are presented.

  19. Operation analysis of AC traction motors in terms of electromagnetic torque capability on sustainable railway vehicles

    Directory of Open Access Journals (Sweden)

    Bulucea Cornelia A.

    2016-01-01

    Full Text Available Sustainable operation of electric railway systems represents a significant purpose nowadays in the development of high power and high speed locomotives and trains. At present, high speed electric vehicles mostly work with three-phase induction motors or three-phase synchronous motors as traction motors. The two electric machine types have different efficiencies at different operation points, and experience differences with respect to safety, speed and power, energy use and exergy efficiency. An important issue that correlates these aspects is the electromagnetic torque developed by an electric traction motor. In order to provide an overview of the technical performance of the operation of sustainable railway systems, a detailed analysis is carried out of the electromagnetic torque capability of AC electric motors utilized as traction motors in modern locomotives of high power and/or high speed. The results of this work may help in enhancing the main criteria for optimising the safe and sustainable operation of electric railway traction systems.

  20. Direct measurements of intermolecular forces by chemical force microscopy

    Science.gov (United States)

    Vezenov, Dmitri Vitalievich

    1999-12-01

    Detailed description of intermolecular forces is key to understanding a wide range of phenomena from molecular recognition to materials failure. The unique features of atomic force microscopy (AFM) to make point contact force measurements with ultra high sensitivity and to generate spatial maps of surface topography and forces have been extended to include measurements between well-defined organic molecular groups. Chemical modification of AFM probes with self-assembled monolayers (SAMs) was used to make them sensitive to specific molecular interactions. This novel chemical force microscopy (CFM) technique was used to probe forces between different molecular groups in a range of environments (vacuum, organic liquids and aqueous solutions); measure surface energetics on a nanometer scale; determine pK values of the surface acid and base groups; measure forces to stretch and unbind a short synthetic DNA duplex and map the spatial distribution of specific functional groups and their ionization state. Studies of adhesion forces demonstrated the important contribution of hydrogen bonding to interactions between simple organic functionalities. The chemical identity of the tip and substrate surfaces as well as the medium had a dramatic effect on adhesion between model monolayers. A direct correlation between surface free energy and adhesion forces was established. The adhesion between epoxy polymer and model mixed SAMs varied with the amount of hydrogen bonding component in the monolayers. A consistent interpretation of CFM measurements in polar solvents was provided by contact mechanics models and intermolecular force components theory. Forces between tips and surfaces functionalized with SAMs terminating in acid or base groups depended on their ionization state. A novel method of force titration was introduced for highly local characterization of the pK's of surface functional groups. The pH-dependent changes in friction forces were exploited to map spatially the

  1. Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives.

    Science.gov (United States)

    Baracco, Bruno; Fuentes, M Victoria; Garrido, Miguel A; González-López, Santiago; Ceballos, Laura

    2013-07-01

    The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers' instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24 h, 37 °C) or thermocycled (5,000 cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α = 0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24 h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin-dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.

  2. ANALYSIS OF ENERGY EFFICIENCY OF OPERATING MODES OF ELECTRICAL SYSTEMS WITH THE TRACTION LOADS

    Directory of Open Access Journals (Sweden)

    V. E. Bondarenko

    2017-03-01

    Full Text Available Innovative scenarios of reliable energy supply of transportation process aimed at reducing the specific energy consumption and increase energy efficiency of the systems of electric traction. The paper suggests innovative energy saving directions in traction networks of railways and new circuit solutions accessing traction substations in energy systems networks, ensure energy security of the transportation process. To ensure the energy security of rail transport special schemes were developed to propose the concept of external power traction substations, which would increase the number of connections to the networks of 220 – 330 kV, as well as the creation of transport and energy corridors, development of its own supply of electric networks of 110 kV substations and mobile RP-110 kV of next generation. Therefore, the investment program of the structures owned by the Ukrainian Railways (Ukrzaliznytsia need to be synchronized in their technological characteristics, as well as the criteria of reliability and quality of power supply with the same external energy investment programs. It is found that without any load on left or right supplying arm one of two less loaded phases of traction transformer begins generating specific modes in the supplying three-phase line. Thus, modes of mobile substation cause leakage in one of the phases of the supply line of traction transformers of active-capacitive current, and as a result generating energy in the main power line of 154 kV, which is fixed and calculated by electricity meters. For these three phase mode supply network is necessary to use 1st algorithm, i.e. taking into account the amount of electricity as the energy in all phases. For effective application of reactive power compensation devices in the AC traction power supply systems it is proposed to develop regulatory documentation on necessity of application and the order of choice of parameters and placement of compensation systems taking into

  3. Adhesive Bioactive Coatings Inspired by Sea Life.

    Science.gov (United States)

    Rego, Sónia J; Vale, Ana C; Luz, Gisela M; Mano, João F; Alves, Natália M

    2016-01-19

    Inspired by nature, in particular by the marine mussels adhesive proteins (MAPs) and by the tough brick-and-mortar nacre-like structure, novel multilayered films are prepared in the present work. Organic-inorganic multilayered films, with an architecture similar to nacre based on bioactive glass nanoparticles (BG), chitosan, and hyaluronic acid modified with catechol groups, which are the main components responsible for the outstanding adhesion in MAPs, are developed for the first time. The biomimetic conjugate is prepared by carbodiimide chemistry and analyzed by ultraviolet-visible spectrophotometry. The buildup of the multilayered films is monitored with a quartz crystal microbalance with dissipation monitoring, and their topography is characterized by atomic force microscopy. The mechanical properties reveal that the films containing catechol groups and BG present an enhanced adhesion. Moreover, the bioactivity of the films upon immersion in a simulated body fluid solution is evaluated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. It was found that the constructed films promote the formation of bonelike apatite in vitro. Such multifunctional mussel inspired LbL films, which combine enhanced adhesion and bioactivity, could be potentially used as coatings of a variety of implants for orthopedic applications.

  4. Microfabricated adhesive mimicking gecko foot-hair

    Science.gov (United States)

    Geim, A. K.; Dubonos, S. V.; Grigorieva, I. V.; Novoselov, K. S.; Zhukov, A. A.; Shapoval, S. Yu.

    2003-07-01

    The amazing climbing ability of geckos has attracted the interest of philosophers and scientists alike for centuries. However, only in the past few years has progress been made in understanding the mechanism behind this ability, which relies on submicrometre keratin hairs covering the soles of geckos. Each hair produces a miniscule force ~10-7 N (due to van der Waals and/or capillary interactions) but millions of hairs acting together create a formidable adhesion of ~10 N cm-2: sufficient to keep geckos firmly on their feet, even when upside down on a glass ceiling. It is very tempting to create a new type of adhesive by mimicking the gecko mechanism. Here we report on a prototype of such 'gecko tape' made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion. Our approach shows a way to manufacture self-cleaning, re-attachable dry adhesives, although problems related to their durability and mass production are yet to be resolved.

  5. an Adhesive Patch

    Directory of Open Access Journals (Sweden)

    S. Mojtaba Taghizadeh

    2013-01-01

    Full Text Available Drug-in-adhesive transdermal drug delivery systems  TDDSs containing stimulants, termed as energetic substances, such as caffeine and pantothenic acid, were studied. Caffeine is a white crystalline substance and a stimulant to central nervous system. In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. Pantothenic acid, also recognized as vitamin B5, is a water-soluble vitamin. For many animals, pantothenic acid is an essential nutrient. Animals require pantothenic acid to synthesize and metabolize proteins, carbohydrates and fats. For this purpose caffeine and pantothenic acid were  used  as  drug  components with  6.32%  and  1.12%  loadings,  in  different functional and non-functional acrylic pressure sensitive adhesives (PSAs of 52.89%, respectively. Ethylene glycol as a chemical enhancer was used in all TDDSs with 39.67%. The effect of PSAs  type on  in vitro  release and adhesion properties  (peel strength and tack values from drug delivery devices were evaluated. It was found that TDDS containing -COOH functional PSA showed  the  lowest steady state fux. The adhesion properties of the samples were improved by addition of functional acrylic PSA in formulations.

  6. Leukocyte adhesion deficiencies

    NARCIS (Netherlands)

    van de Vijver, Edith; van den Berg, Timo K.; Kuijpers, Taco W.

    2013-01-01

    During inflammation, leukocytes play a key role in maintaining tissue homeostasis through elimination of pathogens and removal of damaged tissue. Leukocytes migrate to the site of inflammation by crawling over and through the blood vessel wall, into the tissue. Leukocyte adhesion deficiencies (ie,

  7. Adhesive tape exfoliation

    DEFF Research Database (Denmark)

    Bohr, Jakob

    2015-01-01

    Single-crystal graphite can be cleaved by the use of an adhesive tape. This was also the initial route for obtaining graphene, a one-layer thick graphite slab. In this letter a few simple and fun considerations are presented in an attempt to shed some light on why this procedure is successful...

  8. Wood Composite Adhesives

    Science.gov (United States)

    Gomez-Bueso, Jose; Haupt, Robert

    The global environment, in which phenolic resins are being used for wood composite manufacture, has changed significantly during the last decade. This chapter reviews trends that are driving the use and consumption of phenolic resins around the world. The review begins with recent data on volume usage and regional trends, followed by an analysis of factors affecting global markets. In a section on environmental factors, the impact of recent formaldehyde emission regulations is discussed. The section on economics introduces wood composite production as it relates to the available adhesive systems, with special emphasis on the technical requirement to improve phenolic reactivity. Advances in composite process technology are introduced, especially in regard to the increased demands the improvements place upon adhesive system performance. The specific requirements for the various wood composite families are considered in the context of adhesive performance needs. The results of research into current chemistries are discussed, with a review of recent findings regarding the mechanisms of phenolic condensation and acceleration. Also, the work regarding alternate natural materials, such as carbohydrates, lignins, tannins, and proteinaceous materials, is presented. Finally, new developments in alternative adhesive technologies are reported.

  9. Friction and adhesion of gecko-inspired PDMS flaps on rough surfaces.

    Science.gov (United States)

    Yu, Jing; Chary, Sathya; Das, Saurabh; Tamelier, John; Turner, Kimberly L; Israelachvili, Jacob N

    2012-08-07

    Geckos have developed a unique hierarchical structure to maintain climbing ability on surfaces with different roughness, one of the extremely important parameters that affect the friction and adhesion forces between two surfaces. Although much attention has been paid on fabricating various structures that mimic the hierarchical structure of a gecko foot, yet no systematic effort, in experiment or theory, has been made to quantify the effect of surface roughness on the performance of the fabricated structures that mimic the hierarchical structure of geckos. Using a modified surface forces apparatus (SFA), we measured the adhesion and friction forces between microfabricated tilted PDMS flaps and optically smooth SiO(2) and rough SiO(2) surfaces created by plasma etching. Anisotropic adhesion and friction forces were measured when sliding the top glass surface along (+y) and against (-y) the tilted direction of the flaps. Increasing the surface roughness first increased the adhesion and friction forces measured between the flaps and the rough surface due to topological matching of the two surfaces but then led to a rapid decrease in both of these forces. Our results demonstrate that the surface roughness significantly affects the performance of gecko mimetic adhesives and that different surface textures can either increase or decrease the adhesion and friction forces of the fabricated adhesives.

  10. Efficacy of Prone Lumbar Traction on Chronic Discogenic Low Back Pain and Disability

    Directory of Open Access Journals (Sweden)

    Mahmoud Beyki

    2007-09-01

    Full Text Available Objectives: To compare the outcomes of prone and supine lumbar traction in patients with chronic discogenic low back pain. Methods: The test was prospective and randomized control trial. The structure of trial was Urban Physical Medicine and Rehabilitation clinic. Participants was included of A total of 124 subjects with chronic low back pain (LBP and evidence of a degenerative and/or herniated inter-vertebral disk at 1 or more levels of the lumbar spine, who have not our exclusion criteria. There was A 4-week course of lumbar traction, prone or supine in case and control groups consecutively, consisting of six 30-minute sessions every other days, followed by four 30-minute sessions every 3 days. The numeric Visual pain rating scale and the Oswestry Disability Index (ODI were completed at pre-intervention and discharge (within 2 weeks of the last visit. Results: A total of 124 subjects completed the treatment protocol. We noted significant improvements for all post-intervention outcome scores when compared with pre-intervention scores (P<0.01. Also found significant difference between 2 groups in favor of prone traction (P<0.01 Discussion: Traction applied in the prone position for 4 weeks was associated with improvements in pain intensity and ODI scores at discharge, in a sample of patients with activity limiting LBP. However, because we lacked a reasonable long time follow-up, we cannot imply a long lasting relationship between the traction and outcome, and a long time follow-up is suggested.

  11. Effects of Different Angles of the Traction Table on Lumbar Spine Ligaments: A Finite Element Study.

    Science.gov (United States)

    Farajpour, Hekmat; Jamshidi, Nima

    2017-12-01

    The traction bed is a noninvasive device for treating lower back pain caused by herniated intervertebral discs. In this study, we investigated the impact of the traction bed on the lower back as a means of increasing the disc height and creating a gap between facet joints. Computed tomography (CT) images were obtained from a female volunteer and a three-dimensional (3D) model was created using software package MIMICs 17.0. Afterwards, the 3D model was analyzed in an analytical software (Abaqus 6.14). The study was conducted under the following traction loads: 25%, 45%, 55%, and 85% of the whole body weight in different angles. Results indicated that the loading angle in the L3-4 area had 36.8%, 57.4%, 55.32%, 49.8%, and 52.15% effect on the anterior longitudinal ligament, posterior longitudinal ligament, intertransverse ligament, interspinous ligament, and supraspinous ligament, respectively. The respective values for the L4-5 area were 32.3%, 10.6%, 53.4%, 56.58%, and 57.35%. Also, the body weight had 63.2%, 42.6%, 44.68%, 50.2%, and 47.85% effect on the anterior longitudinal ligament, posterior longitudinal ligament, intertransverse ligament, interspinous ligament, and supraspinous ligament, respectively. The respective values for the L4-5 area were 67.7%, 89.4%, 46.6%, 43.42% and 42.65%. The authenticity of results was checked by comparing with the experimental data. The results show that traction beds are highly effective for disc movement and lower back pain relief. Also, an optimal angle for traction can be obtained in a 3D model analysis using CT or magnetic resonance imaging images. The optimal angle would be different for different patients and thus should be determined based on the decreased height of the intervertebral disc, weight and height of patients.

  12. Posterior-only surgery with preoperative skeletal traction for management of severe scoliosis.

    Science.gov (United States)

    Mehrpour, Saeedreza; Sorbi, Reza; Rezaei, Reza; Mazda, Keyvan

    2017-04-01

    The surgical treatment of severe adolescent spinal deformities is challenging and carries substantial risks of mortality and morbidity. To mitigate this risk, surgeons have employed various methods as this study designed to evaluate the safety and effectiveness of preoperative halo-femoral or halo gravity traction (HGT) followed by posterior-only surgery in the management of severe scoliosis. A total number of 23 patients with severe scoliosis treated by preoperative skeletal traction (halo gravity or halo femoral) followed by posterior fusion and instrumentation in one stage. All patients were followed for a minimum of 2 years after surgery. The average age of the patients was 12.7 years at the time of surgery. Mean of the Cobb angle improved from 99.9° ± 8.2° preoperatively to 75.3° ± 8° post-traction and 49.5° ± 7.7° postoperatively. Kyphosis angle corrected from 56.4° ± 9.5° to 38.6° ± 5.8°. The preop-FVC% was 41 ± 6.1% and after 1 year follow-up FVC% was 45.7 ± 7.7%. No patients required an anterior release due to amount of their deformity. Despite the benefits of modern instrumentation procedures, the treatment of severe scoliosis can be very competing. We think that by applying preoperative halo femoral traction and halo-gravity traction, managing severe scoliosis will be in safe and easy manner and can lead to better deformity correction and less neurological complications and facilitate to avoid anterior operation for severe scoliosis and its related complications.

  13. ELECTRODYNAMICS OF TRANSMISSION AND LOSSES OF POWER IN THE DEVICES OF ELECTRIC TRACTION SYSTEMS

    Directory of Open Access Journals (Sweden)

    M. O. Kostin

    2014-01-01

    Full Text Available Purpose. Theoretical justification of the "field" approach (based on electromagnetic field to the transmission and losses of power in the devices of traction power supply systems and electric rolling stock. Methodology. The methods of electromagnetic field theory and, in particular, the theory and practice of electromagnetic energy transmission based on the concept of the Poynting vector and elements of the theory of propagation, reflection and refraction of plane electromagnetic waves were used. Findings. Theoretical studies of electromagnetic energy transmission from the traction substation to the electric rolling stock through dielectric (air surrounding traction network: between the contact wire and the rail were carried out. It is proposed strategic designing "squat" (low types of electric rolling stock. The components of electric energy flow through the roof of electric rolling stock and its frontal part of the body were estimated. This allows reliable etimating active power losses in electric traction system. To compensate the reactive power consumed by electric rolling stock, which is conditioned by standing waves, it is proposed (for extinction of the the last to develop and put in front of electric rolling stock the layer of particular environment with the necessary parameters. Originality. The "field" principle of the power transmission analysis and its losses arising in electric traction system was first proposed. The laws of motion of electromagnetic energy flows through the roof and the frontal part of the body of electric rolling stock were established. Practical value. An expression of the absolute value of the Poynting vector in the points of dielectric (air between the contact wire and the rail was obtained. This allows assessing the highest density of energy, which is transferred to the time unit and predicting the main dimensions of the unit of electric rolling stock. The energy indices of the roof of electric rolling stock

  14. Long-Life, Lightweight, Multi-Roller Traction Drives for Planetary Vehicle Surface Exploration

    Science.gov (United States)

    Klein, Richard C.; Fusaro, Robert L.; Dimofte, Florin

    2012-01-01

    NASA s initiative for Lunar and Martian exploration will require long lived, robust drive systems for manned vehicles that must operate in hostile environments. The operation of these mechanical drives will pose a problem because of the existing extreme operating conditions. Some of these extreme conditions include operating at a very high or very cold temperature, operating over a wide range of temperatures, operating in very dusty environments, operating in a very high radiation environment, and operating in possibly corrosive environments. Current drive systems use gears with various configurations of teeth. These gears must be lubricated with oil (or grease) and must have some sort of a lubricant resupply system. For drive systems, oil poses problems such as evaporation, becoming too viscous and eventually freezing at cold temperatures, being too thin to lubricate at high temperatures, being degraded by the radiation environment, being contaminated by the regolith (soil), and if vaporized (and not sealed), it will contaminate the regolith. Thus, it may not be advisable or even possible to use oil because of these limitations. An oil-less, compact traction vehicle drive is a drive designed for use in hostile environments like those that will be encountered on planetary surfaces. Initially, traction roller tests in vacuum were conducted to obtain traction and endurance data needed for designing the drives. From that data, a traction drive was designed that would fit into a prototype lunar rover vehicle, and this design data was used to construct several traction drives. These drives were then tested in air to determine their performance characteristics, and if any final corrections to the designs were necessary. A limitation with current speed reducer systems such as planetary gears and harmonic drives is the high-contact stresses that occur at tooth engagement and in the harmonic drive wave generator interface. These high stresses induce high wear of solid

  15. CALCULATION OF MAGNETIC CHARACTERISTICS OF TRACTION ELECTRIC ENGINE WITH THE USE OF IMPROVED UNIVERSAL MAGNETIC CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    A. Y. Drubetskyi

    2017-06-01

    Full Text Available Purpose. The article is aimed to develop a technique for calculating the magnetic characteristics of uncompensated traction electric motors (TEM at any degree of attenuation of excitation based on the approximating expression for improved universal magnetic characteristics (UMC. It is also necessary to conduct an analysis of expressions for improved UMC with the aim of finding an expression that most fully satisfies the requirements for developing a technique for determining the inductive parameters of TEM. Methodology. It is necessary to determine the saturation coefficient for each degree of attenuation of the excitation for building the characteristics with the improved UMC. This can only be done analytically. To simplify the analytical finding of the saturation coefficient, the method based on solving a system of two equations is proposed, one of which is UMC itself, and the second one is a straight line whose angular coefficient is proportional to the saturation coefficient. Resulting values of the saturation coefficient for the excitation degrees β < 1 are essentially the coefficients of the shape of the magnetic characteristic. To get rid of the need to determine the coefficients of approximation each time in the calculation of characteristics a form of improved UMC is proposed, in which the magnetomotive force (MMF of the excitation winding serves as the argument's role. Findings. Using the improved UMC it is possible to calculate the characteristics of uncompensated TEMs for any degree of attenuation of excitation. The accuracy of the calculation at β = 1 does not differ from that in the calculation for UMC, proposed by Prof. M. D. Nakhodkin. The same accuracy is preserved at excitation degrees that are different from unity. Originality. An analytical technique for calculating the magnetic (speed characteristics of uncompensated TEM for any degree of attenuation with the help of an improved UMC is proposed. The analytical technique

  16. Fibrous hyaluronic acid hydrogels that direct MSC chondrogenesis through mechanical and adhesive cues.

    Science.gov (United States)

    Kim, Iris L; Khetan, Sudhir; Baker, Brendon M; Chen, Christopher S; Burdick, Jason A

    2013-07-01

    Electrospinning has recently gained much interest due to its ability to form scaffolds that mimic the nanofibrous nature of the extracellular matrix, such as the size and depth-dependent alignment of collagen fibers within hyaline cartilage. While much progress has been made in developing bulk, isotropic hydrogels for tissue engineering and understanding how the microenvironment of such scaffolds affects cell response, these effects have not been extensively studied in a nanofibrous system. Here, we show that the mechanics (through intrafiber crosslink density) and adhesivity (through RGD density) of electrospun hyaluronic acid (HA) fibers significantly affect human mesenchymal stem cell (hMSC) interactions and gene expression. Specifically, hMSC spreading, proliferation, and focal adhesion formation were dependent on RGD density, but not on the range of fiber mechanics investigated. Moreover, traction-mediated fiber displacements generally increased with more adhesive fibers. The expression of chondrogenic markers, unlike trends in cell spreading and cytoskeletal organization, was influenced by both fiber mechanics and adhesivity, in which softer fibers and lower RGD densities generally enhanced chondrogenesis. This work not only reveals concurrent effects of mechanics and adhesivity in a fibrous context, but also highlights fibrous HA hydrogels as a promising scaffold for future cartilage repair strategies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Gecko-Inspired Electrospun Flexible Fiber Arrays for Adhesion

    Science.gov (United States)

    Najem, Johnny F.

    The ability of geckos to adhere to vertical solid surfaces comes from their remarkable feet with millions of projections terminating in nanometer spatulae. We present a simple yet robust method for fabricating directionally sensitive dry adhesives. By using electrospun nylon 6 nanofiber arrays, we create gecko-inspired dry adhesives, that are electrically insulating, and that show shear adhesion strength of 27 N/cm2 on a glass slide. This measured value is 270% that reported of gecko feet and 97-fold above normal adhesion strength of the same arrays. The data indicate a strong shear binding-on and easy normal lifting-off. This anisotropic strength distribution is attributed to an enhanced shear adhesion strength with decreasing fiber diameter (d) and an optimum performance of nanofiber arrays in the shear direction over a specific range of thicknesses. With use of electrospinning, we report the fabrication of nylon 6 nanofiber arrays that show a friction coefficient (mu) of 11.5. These arrays possess significant shear adhesion strength and low normal adhesion strength. Increasing the applied normal load considerably enhances the shear adhesion strength and mu, irrespective of d and fiber arrays thickness (T). Fiber bending stiffness and fiber surface roughness are considerably decreased with diminishing d while fiber packing density is noticeably increased. These enhancements are proposed to considerably upsurge the shear adhesion strength between nanofiber arrays and a glass slide. The latter upsurge is mainly attributed to a sizeable proliferation in van der Waals (vdW) forces. These nanofiber arrays can be alternatively bound-on and lifted-off over a glass slide with a trivial decrease in the initial mu and adhesion strength. By using selective coating technique, we have also created hierarchical structures having closely packed nanofibers with d of 50 nm. We determine the effects of applied normal load, fiber surface roughness, loading angle, d, T, and repeated

  18. Physically based principles of cell adhesion mechanosensitivity in tissues

    International Nuclear Information System (INIS)

    Ladoux, Benoit; Nicolas, Alice

    2012-01-01

    The minimal structural unit that defines living organisms is a single cell. By proliferating and mechanically interacting with each other, cells can build complex organization such as tissues that ultimately organize into even more complex multicellular living organisms, such as mammals, composed of billions of single cells interacting with each other. As opposed to passive materials, living cells actively respond to the mechanical perturbations occurring in their environment. Tissue cell adhesion to its surrounding extracellular matrix or to neighbors is an example of a biological process that adapts to physical cues. The adhesion of tissue cells to their surrounding medium induces the generation of intracellular contraction forces whose amplitude adapts to the mechanical properties of the environment. In turn, solicitation of adhering cells with physical forces, such as blood flow shearing the layer of endothelial cells in the lumen of arteries, reinforces cell adhesion and impacts cell contractility. In biological terms, the sensing of physical signals is transduced into biochemical signaling events that guide cellular responses such as cell differentiation, cell growth and cell death. Regarding the biological and developmental consequences of cell adaptation to mechanical perturbations, understanding mechanotransduction in tissue cell adhesion appears as an important step in numerous fields of biology, such as cancer, regenerative medicine or tissue bioengineering for instance. Physicists were first tempted to view cell adhesion as the wetting transition of a soft bag having a complex, adhesive interaction with the surface. But surprising responses of tissue cell adhesion to mechanical cues challenged this view. This, however, did not exclude that cell adhesion could be understood in physical terms. It meant that new models and descriptions had to be created specifically for these biological issues, and could not straightforwardly be adapted from dead matter

  19. Adhesive bonding of wood materials

    Science.gov (United States)

    Charles B. Vick

    1999-01-01

    Adhesive bonding of wood components has played an essential role in the development and growth of the forest products industry and has been a key factor in the efficient utilization of our timber resource. The largest use of adhesives is in the construction industry. By far, the largest amounts of adhesives are used to manufacture building materials, such as plywood,...

  20. METHODS AND RESEARCH CONCERNING SERVICE LIFE EXTENSION OF SUPORTING STRUCTURES OF TRACTION ROLLING STOCK FOR INDUSTRIAL TRANSPORT

    Directory of Open Access Journals (Sweden)

    O. M. Bondarev

    2014-04-01

    Full Text Available Purpose. The purpose of work is scientifically grounded introduction of the acquired techniques into works for service life extension of the traction and motor rolling stock for industrial transport. Methodology. To achieve the purpose it was analyzed the acquired techniques for service life extension of the traction and motor rolling stock for mainline transport. The acquired techniques during solution of problems concerning the service life extension of rolling stock units were adapted to the locomotives TGM6A and traction aggregates OPE1. Findings. On the basis of experimental and theoretical complex of studies some results were obtained. They gave the ground to determine the possibility of acquired techniques use when solving the problems on service life extension of rolling stock units concerning locomotives TGM6A and traction aggregates OPE1. Originality. On the basis of conducted experimental and theoretical studies scientific maintenance of the works providing extension of service life of traction and motor units of industrial rolling stock was executed. Practical value. Technical solutions and measures, which have to be carried out during operation within the prolonged appointed service life of traction and motor units of industrial rolling stock enterprises using locomotives and traction aggregates to provide the basic technological cycles were developed.

  1. Diagnostic performance of direct traction MR arthrography of the hip: detection of chondral and labral lesions with arthroscopic comparison

    International Nuclear Information System (INIS)

    Schmaranzer, Florian; Klauser, Andrea; Henninger, Benjamin; Kogler, Michael; Schmaranzer, Ehrenfried; Forstner, Thomas; Reichkendler, Markus

    2015-01-01

    To assess diagnostic performance of traction MR arthrography of the hip in detection and grading of chondral and labral lesions with arthroscopic comparison. Seventy-five MR arthrograms obtained ± traction of 73 consecutive patients (mean age, 34.5 years; range, 14-54 years) who underwent arthroscopy were included. Traction technique included weight-adapted traction (15-23 kg), a supporting plate for the contralateral leg, and intra-articular injection of 18-27 ml (local anaesthetic and contrast agent). Patients reported on neuropraxia and on pain. Two blinded readers independently assessed femoroacetabular cartilage and labrum lesions which were correlated with arthroscopy. Interobserver agreement was calculated using κ values. Joint distraction ± traction was evaluated in consensus. No procedure had to be stopped. There were no cases of neuropraxia. Accuracy for detection of labral lesions was 92 %/93 %, 91 %/83 % for acetabular lesions, and 92 %/88 % for femoral cartilage lesions for reader 1/reader 2, respectively. Interobserver agreement was moderate (κ = 0.58) for grading of labrum lesions and substantial (κ = 0.7, κ = 0.68) for grading of acetabular and femoral cartilage lesions. Joint distraction was achieved in 72/75 and 14/75 hips with/without traction, respectively. Traction MR arthrography safely enabled accurate detection and grading of labral and chondral lesions. (orig.)

  2. Diagnostic performance of direct traction MR arthrography of the hip: detection of chondral and labral lesions with arthroscopic comparison

    Energy Technology Data Exchange (ETDEWEB)

    Schmaranzer, Florian; Klauser, Andrea; Henninger, Benjamin [Medical University Innsbruck, Department of Radiology, Innsbruck (Austria); Kogler, Michael; Schmaranzer, Ehrenfried [District Hospital St. Johann in Tyrol, Department of Radiology, St. Johann in Tyrol (Austria); Forstner, Thomas [Johannes Keppler University, Department for Applied Systems Research and Statistics, Linz (Austria); Reichkendler, Markus [District Hospital St. Johann in Tyrol, Department of Orthopedic Surgery, St. Johann in Tyrol (Austria)

    2015-06-01

    To assess diagnostic performance of traction MR arthrography of the hip in detection and grading of chondral and labral lesions with arthroscopic comparison. Seventy-five MR arthrograms obtained ± traction of 73 consecutive patients (mean age, 34.5 years; range, 14-54 years) who underwent arthroscopy were included. Traction technique included weight-adapted traction (15-23 kg), a supporting plate for the contralateral leg, and intra-articular injection of 18-27 ml (local anaesthetic and contrast agent). Patients reported on neuropraxia and on pain. Two blinded readers independently assessed femoroacetabular cartilage and labrum lesions which were correlated with arthroscopy. Interobserver agreement was calculated using κ values. Joint distraction ± traction was evaluated in consensus. No procedure had to be stopped. There were no cases of neuropraxia. Accuracy for detection of labral lesions was 92 %/93 %, 91 %/83 % for acetabular lesions, and 92 %/88 % for femoral cartilage lesions for reader 1/reader 2, respectively. Interobserver agreement was moderate (κ = 0.58) for grading of labrum lesions and substantial (κ = 0.7, κ = 0.68) for grading of acetabular and femoral cartilage lesions. Joint distraction was achieved in 72/75 and 14/75 hips with/without traction, respectively. Traction MR arthrography safely enabled accurate detection and grading of labral and chondral lesions. (orig.)

  3. Integrated Cooling System for Induction Motor Traction Drives, CARAT Program Phase Two Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Konrad, Charles E. [VPT, Inc., Blacksburg, VA (United States)

    2002-12-03

    This Program is directed toward improvements in electric vehicle/hybrid electric vehicle traction systems, and in particular, the development of a low cost, highly efficient, compact traction motor-controller system targeted for high volume automotive use. Because of the complex inter-relationships between the motor and the controller, the combination of motor and controller must be considered as a system in the design and evaluation of overall cost and performance. The induction motor is ideally suited for use as a traction motor because of its basic ruggedness, low cost, and high efficiency. As one can see in Figure 1.1, the induction motor traction drive has been continually evolving through a succession of programs spanning the past fifteen years. VPT marketed an induction motor-based traction drive system, the EV2000, which proved to be a reliable, high performance system that was used in a wide range of vehicles. The EV2000 drives evolved from the Modular Electric Vehicle Program (MEVP) and has been used in vehicles ranging in size from 3,000 lb. autos and utility vans, to 32,000 lb. city transit buses. Vehicles powered by the EV2000 induction motor powertrain have accumulated over 2 million miles of service. The EV2000 induction motor system represents 1993 state-of-the-art technology, and evolved from earlier induction motor programs that drove induction motor speeds up to 15,000 rpm to reduce the motor size and cost. It was recognized that the improvements in power density and motor cost sought in the PNGV program could only be achieved through increases in motor speed. Esson’s Rule for motor power clearly states that the power obtainable from a given motor design is the product of motor speed and volume. In order to meet the CARAT Program objectives, the maximum speed goal of the induction motor designed in this Program was increased from 15,000 rpm to 20,000 rpm while maintaining the efficiency and durability demonstrated by lower speed designs done in

  4. Joining of rubber substrate with bronze surface by the method of molecular adhesion

    International Nuclear Information System (INIS)

    Oravec, J.; Preto, J.; Hronkovic, J.; Melus, P.; Hirahara, H.; Sang, J.

    2017-01-01

    During the adhesion process using the adhesives there are many risks of defects caused by boundary stress, strength and to resolve these traditional adhesive problems a method called molecule adhesion technology, was used. This method can successfully adhere different materials and has the advantages such as material independence and strong adhesion strength without any adhesive agent. The impact of selected coupling agents on the green and final adhesion on the boundary bronze surface - natural rubber based coating blend was studied in the presented work. Wires of bronze (Cu/Sn 96:4) coated steel bead wire were submerged in solutions of coupling agents in ethanol for 30 s at various temperature and dried. The effect of the surface modification was evaluated by measuring of XPS, FT-IR, the morphology of the brass plate surfaces after the treatment was studied by the atomic force microscopy (AFM). (authors)

  5. Cell adhesion on nanotextured slippery superhydrophobic substrates.

    Science.gov (United States)

    Di Mundo, Rosa; Nardulli, Marina; Milella, Antonella; Favia, Pietro; d'Agostino, Riccardo; Gristina, Roberto

    2011-04-19

    In this work, the response of Saos2 cells to polymeric surfaces with different roughness/density of nanometric dots produced by a tailored plasma-etching process has been studied. Topographical features have been evaluated by atomic force microscopy, while wetting behavior, in terms of water-surface adhesion energy, has been evaluated by measurements of drop sliding angle. Saos2 cytocompatibility has been investigated by scanning electron microscopy, fluorescent microscopy, and optical microscopy. The similarity in outer chemical composition has allowed isolation of the impact of the topographical features on cellular behavior. The results indicate that Saos2 cells respond differently to surfaces with different nanoscale topographical features, clearly showing a certain inhibition in cell adhesion when the nanoscale is particularly small. This effect appears to be attenuated in surfaces with relatively bigger nanofeatures, though these express a more pronounced slippery/dry wetting character. © 2011 American Chemical Society

  6. Geckos as Springs: Mechanics Explain Across-Species Scaling of Adhesion.

    Directory of Open Access Journals (Sweden)

    Casey A Gilman

    Full Text Available One of the central controversies regarding the evolution of adhesion concerns how adhesive force scales as animals change in size, either among or within species. A widely held view is that as animals become larger, the primary mechanism that enables them to climb is increasing pad area. However, prior studies show that much of the variation in maximum adhesive force remains unexplained, even when area is accounted for. We tested the hypothesis that maximum adhesive force among pad-bearing gecko species is not solely dictated by toepad area, but also depends on the ratio of toepad area to gecko adhesive system compliance in the loading direction, where compliance (C is the change in extension (Δ relative to a change in force (F while loading a gecko's adhesive system (C = dΔ/dF. Geckos are well-known for their ability to climb on a range of vertical and overhanging surfaces, and range in mass from several grams to over 300 grams, yet little is understood of the factors that enable adhesion to scale with body size. We examined the maximum adhesive force of six gecko species that vary in body size (~2-100 g. We also examined changes between juveniles and adults within a single species (Phelsuma grandis. We found that maximum adhesive force and toepad area increased with increasing gecko size, and that as gecko species become larger, their adhesive systems become significantly less compliant. Additionally, our hypothesis was supported, as the best predictor of maximum adhesive force was not toepad area or compliance alone, but the ratio of toepad area to compliance. We verified this result using a synthetic "model gecko" system comprised of synthetic adhesive pads attached to a glass substrate and a synthetic tendon (mechanical spring of finite stiffness. Our data indicate that increases in toepad area as geckos become larger cannot fully account for increased adhesive abilities, and decreased compliance must be included to explain the scaling of

  7. Efficacy of denture adhesives in maxillary dentures using gnathodynamometry: a comparative study.

    Science.gov (United States)

    Polyzois, Gregory; Lagouvardos, Panagiotis; Frangou, Maria; Stefaniotis, Theodoros

    2011-07-01

    The purpose of this study was to investigate the effect of four commercially available denture adhesives on the incisal and premolar dislodgement forces of maxillary complete dentures by using an electronic and disposable gnathodynamometer and compare the measured incisal forces for differences. This study was conducted with 12 complete maxillary denture wearers. Four commercially available denture adhesives Super Corega(®), Corega Ultra(®), Super Corega Powder(®) and Fittydent Cationic(®) were investigated. Testing protocol and sequence included baseline measurements without adhesives (control) for previous and new dentures and then replications of measurements with the four adhesives. Maximum dislodgement forces were recorded in two sites between central incisors and the left 2nd premolars by using an electronic and disposable gnathodynamometer. To estimate the effect of the different adhesives on the dislodgement forces, data were analyzed by a 2- and 3-way ANOVA, while for estimating the agreement of the two devices a Bland-Altman and Mountain plots were used. ANOVAs indicated significant differences between adhesives (p adhesives increase the denture dislodgement forces, but with differences among them. The two devices do not highly agree with each other, but each one alone is useful in estimating dislodgement forces in clinical practice and research.

  8. Experimental approach for adhesion strength of ATF cladding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun; Kim, Hyochan; Yang, Yongsik; In, Wangkee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Haksung [Hanyang University, Seoul (Korea, Republic of)

    2016-10-15

    The quality of a coating depends on the quality of its adhesion bond strength between the coating and the underlying substrate. Therefore, it is essential to evaluate the adhesion properties of the coating. There are many available test methods for the evaluation of coatings adhesion bond strength. Considering these restrictions of the coated cladding, the scratch test is useful for evaluation of adhesion properties compared to other methods. The purpose of the present study is to analyze the possibility of adhesion bond strength evaluation of ATF coated cladding by scratch testing on coatings cross sections. Experimental approach for adhesion strength of ATF coated cladding was investigated in the present study. The scratch testing was chosen as a testing method. Uncoated zircaloy-4 tube was employed as a reference and plasma spray and arc ion coating were selected as a ATF coated claddings for comparison. As a result, adhesion strengths of specimens affect the measured normal and tangential forces. For the future, the test will be conducted for CrAl coated cladding by laser coating, which is the most promising ATF cladding. Computational analysis with finite element method will also be conducted to analyze a stress distribution in the cladding tube.

  9. Syndecans and cell adhesion

    DEFF Research Database (Denmark)

    Couchman, J R; Chen, L; Woods, A

    2001-01-01

    Now that transmembrane signaling through primary cell-matrix receptors, integrins, is being elucidated, attention is turning to how integrin-ligand interactions can be modulated. Syndecans are transmembrane proteoglycans implicated as coreceptors in a variety of physiological processes, including...... cell adhesion, migration, response to growth factors, development, and tumorigenesis. This review will describe this family of proteoglycans in terms of their structures and functions and their signaling in conjunction with integrins, and indicate areas for future research....

  10. Adhesion between coating layers based on epoxy and silicone

    DEFF Research Database (Denmark)

    Svendsen, Jacob R.; Kontogeorgis, Georgios; Kiil, Søren

    2007-01-01

    The adhesion between a silicon tie-coat and epoxy primers, used in marine coating systems, has been studied in this work. Six epoxy coatings (with varying chain lengths of the epoxy resins), some of which have shown problems with adhesion to the tie-coat during service life, have been considered....... The experimental investigation includes measurements of the surface tension of the tie-coat and the critical surface tensions of the epoxies, topographic investigation of the surfaces of cured epoxy coatings via atomic force microscopy (AFM), and pull-off tests for investigating the strength of adhesion...... to the silicon/epoxy systems. Calculations for determining the roughness factor of the six epoxy coatings (based on the AFM topographies) and the theoretical work of adhesion have been carried out. The coating surfaces are also characterized based on the van Oss-Good theory. Previous studies on the modulus...

  11. Tenomodulin expression in the periodontal ligament enhances cellular adhesion.

    Directory of Open Access Journals (Sweden)

    Yuske Komiyama

    Full Text Available Tenomodulin (Tnmd is a type II transmembrane protein characteristically expressed in dense connective tissues such as tendons and ligaments. Its expression in the periodontal ligament (PDL has also been demonstrated, though the timing and function remain unclear. We investigated the expression of Tnmd during murine tooth eruption and explored its biological functions in vitro. Tnmd expression was related to the time of eruption when occlusal force was transferred to the teeth and surrounding tissues. Tnmd overexpression enhanced cell adhesion in NIH3T3 and human PDL cells. In addition, Tnmd-knockout fibroblasts showed decreased cell adhesion. In the extracellular portions of Tnmd, the BRICHOS domain or CS region was found to be responsible for Tnmd-mediated enhancement of cell adhesion. These results suggest that Tnmd acts on the maturation or maintenance of the PDL by positively regulating cell adhesion via its BRICHOS domain.

  12. Laboratory test for ice adhesion strength using commercial instrumentation.

    Science.gov (United States)

    Wang, Chenyu; Zhang, Wei; Siva, Adarsh; Tiea, Daniel; Wynne, Kenneth J

    2014-01-21

    A laboratory test method for evaluating ice adhesion has been developed employing a commercially available instrument normally used for dynamic mechanical analysis (TA RSA-III). This is the first laboratory ice adhesion test that does not require a custom-built apparatus. The upper grip range of ∼10 mm is an enabling feature that is essential for the test. The method involves removal of an ice cylinder from a polymer coating with a probe and the determination of peak removal force (Ps). To validate the test method, the strength of ice adhesion was determined for a prototypical glassy polymer, poly(methyl methacrylate). The distance of the probe from the PMMA surface has been identified as a critical variable for Ps. The new test provides a readily available platform for investigating fundamental surface characteristics affecting ice adhesion. In addition to the ice release test, PMMA coatings were characterized using DSC, DCA, and TM-AFM.

  13. The effect of water on the gecko adhesive system

    Science.gov (United States)

    Stark, Alyssa Yeager

    The gecko adhesive system is a dry, reversible adhesive that is virtually surface-insensitive due to the utilization of intermolecular van der Waals forces. Remarkably, although detailed models of the adhesive mechanism exist and hundreds of gecko-inspired synthetics have been fabricated, our ability to fully replicate the system still falls short. One reason for this is our limited understanding of how the system performs in natural environments. To begin to resolve this I focused on one particular environmental parameter, water. Although thin layers of water can disrupt van der Waals forces, I hypothesized that geckos are able to retain or regain adhesive function on wet surfaces. I was motivated to investigate this hypothesis because many species of gecko are native to the tropics, a climate where we expect surface water to be prevalent, thus it is likely geckos have some mechanism to overcome the challenges associated with surface water and wetting. Despite the challenge water should pose to adhesion, I found that when tested on hydrophobic substrates geckos cling equally well in air and water. Conversely, on wet hydrophilic substrates geckos cannot support their body weight. Investigating these results further, I found that the superhydrophobic nature of the adhesive toe pads allows geckos to form an air bubble around their foot, which when pressed into contact with a hydrophobic substrate likely removes water from the adhesive interface. When the toe pads are no longer superhydrophobic however, geckos cannot support their body weight and fall from substrates. In order to regain adhesion geckos only need to take about ten steps on a dry substrate to self-dry their toe pads. Finally, when measuring a dynamic component of adhesion, running, we found that geckos are able to maintain speed on misted hydrophobic and hydrophilic substrates, contrary to what we would predict based on static shear adhesion measurements. In conclusion, my research provides a detailed

  14. Effect of surface tension on the behavior of adhesive contact based on Lennard-Jones potential law

    Science.gov (United States)

    Zhu, Xinyao; Xu, Wei

    2018-02-01

    The present study explores the effect of surface tension on adhesive contact behavior where the adhesion is interpreted by long-range intermolecular forces. The adhesive contact is analyzed using the equivalent system of a rigid sphere and an elastic half space covered by a membrane with surface tension. The long-range intermolecular forces are modeled with the Lennard‒Jones (L‒J) potential law. The current adhesive contact issue can be represented by a nonlinear integral equation, which can be solved by Newton‒Raphson method. In contrast to previous studies which consider intermolecular forces as short-range, the present study reveals more details of the features of adhesive contact with surface tension, in terms of jump instabilities, pull-off forces, pressure distribution within the contact area, etc. The transition of the pull-off force is not only consistent with previous studies, but also presents some new interesting characteristics in the current situation.

  15. The nucleus is an intracellular propagator of tensile forces in NIH 3T3 fibroblasts

    Science.gov (United States)

    Alam, Samer G.; Lovett, David; Kim, Dae In; Roux, Kyle J.; Dickinson, Richard B.; Lele, Tanmay P.

    2015-01-01

    ABSTRACT Nuclear positioning is a crucial cell function, but how a migrating cell positions its nucleus is not understood. Using traction-force microscopy, we found that the position of the nucleus in migrating fibroblasts closely coincided with the center point of the traction-force balance, called the point of maximum tension (PMT). Positioning of the nucleus close to the PMT required nucleus–cytoskeleton connections through linker of nucleoskeleton-to-cytoskeleton (LINC) complexes. Although the nucleus briefly lagged behind the PMT following spontaneous detachment of the uropod during migration, the nucleus quickly repositioned to the PMT within a few minutes. Moreover, traction-generating spontaneous protrusions deformed the nearby nucleus surface to pull the nuclear centroid toward the new PMT, and subsequent retraction of these protrusions relaxed the nuclear deformation and restored the nucleus to its original position. We propose that the protruding or retracting cell boundary transmits a force to the surface of the nucleus through the intervening cytoskeletal network connected by the LINC complexes, and that these forces help to position the nucleus centrally and allow the nucleus to efficiently propagate traction forces across the length of the cell during migration. PMID:25908852

  16. Functional adhesive surfaces with “gecko” effect: the concept of contact splitting

    NARCIS (Netherlands)

    Kamperman, M.M.G.; Kroner, E.; Campo, del A.; McMeeking, R.M.; Arzt, E.

    2010-01-01

    Nature has developed reversibly adhesive surfaces whose stickiness has attracted much research attention over the last decade. The central lesson from nature is that “patterned” or “fibrillar” surfaces can produce higher adhesion forces to flat and rough substrates than smooth surfaces. This paper

  17. Elastic coupling of nascent apCAM adhesions to flowing actin networks.

    Science.gov (United States)

    Mejean, Cecile O; Schaefer, Andrew W; Buck, Kenneth B; Kress, Holger; Shundrovsky, Alla; Merrill, Jason W; Dufresne, Eric R; Forscher, Paul

    2013-01-01

    Adhesions are multi-molecular complexes that transmit forces generated by a cell's acto-myosin networks to external substrates. While the physical properties of some of the individual components of adhesions have been carefully characterized, the mechanics of the coupling between the cytoskeleton and the adhesion site as a whole are just beginning to be revealed. We characterized the mechanics of nascent adhesions mediated by the immunoglobulin-family cell adhesion molecule apCAM, which is known to interact with actin filaments. Using simultaneous visualization of actin flow and quantification of forces transmitted to apCAM-coated beads restrained with an optical trap, we found that adhesions are dynamic structures capable of transmitting a wide range of forces. For forces in the picoNewton scale, the nascent adhesions' mechanical properties are dominated by an elastic structure which can be reversibly deformed by up to 1 µm. Large reversible deformations rule out an interface between substrate and cytoskeleton that is dominated by a number of stiff molecular springs in parallel, and favor a compliant cross-linked network. Such a compliant structure may increase the lifetime of a nascent adhesion, facilitating signaling and reinforcement.

  18. Elastic coupling of nascent apCAM adhesions to flowing actin networks.

    Directory of Open Access Journals (Sweden)

    Cecile O Mejean

    Full Text Available Adhesions are multi-molecular complexes that transmit forces generated by a cell's acto-myosin networks to external substrates. While the physical properties of some of the individual components of adhesions have been carefully characterized, the mechanics of the coupling between the cytoskeleton and the adhesion site as a whole are just beginning to be revealed. We characterized the mechanics of nascent adhesions mediated by the immunoglobulin-family cell adhesion molecule apCAM, which is known to interact with actin filaments. Using simultaneous visualization of actin flow and quantification of forces transmitted to apCAM-coated beads restrained with an optical trap, we found that adhesions are dynamic structures capable of transmitting a wide range of forces. For forces in the picoNewton scale, the nascent adhesions' mechanical properties are dominated by an elastic structure which can be reversibly deformed by up to 1 µm. Large reversible deformations rule out an interface between substrate and cytoskeleton that is dominated by a number of stiff molecular springs in parallel, and favor a compliant cross-linked network. Such a compliant structure may increase the lifetime of a nascent adhesion, facilitating signaling and reinforcement.

  19. Advanced state prediction of lithium-ion traction batteries in hybrid and battery electric vehicle applications

    Energy Technology Data Exchange (ETDEWEB)

    Jadidi, Yasser

    2011-07-01

    Automotive power trains with high energy efficiencies - particularly to be found in battery and hybrid electric vehicles - find increasing attention in the focus of reduction of exhaust emissions and increase of mileage. The underlying concept, the electrification of the power train, is subject to the traction battery and its battery management system since the capability of the battery permits and restricts electric propulsion. Consequently, the overall vehicle efficiency and in particular the operation strategy performance strongly depends on the quality of information about the battery. Besides battery technology, the key challenges are given by both the accurate prediction of battery behaviour and the electrochemical battery degradation that leads to power and capacity fade of the traction battery. This book provides the methodology for development of a battery state monitoring and prediction algorithm for application in a battery management system that accounts for the effects of electrochemical degradation. (orig.)

  20. Concept for a Differential Lock and Traction Control Model in Automobiles

    Science.gov (United States)

    Shukul, A. K.; Hansra, S. K.

    2014-01-01

    The automobile is a complex integration of electronics and mechanical components. One of the major components is the differential which is limited due to its shortcomings. The paper proposes a concept of a cost effective differential lock and traction for passenger cars to sports utility vehicles alike, employing a parallel braking mechanism coming into action based on the relative speeds of the wheels driven by the differential. The paper highlights the employment of minimum number of components unlike the already existing systems. The system was designed numerically for the traction control and differential lock for the world's cheapest car. The paper manages to come up with all the system parameters and component costing making it a cost effective system.