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Sample records for afm tapping mode

  1. Tapping and contact mode imaging of native chromosomes and extraction of genomic DNA using AFM tips

    NASA Astrophysics Data System (ADS)

    Sun, Yingchun; Arakawa, Hideo; Osada, Toshiya; Ikai, Atsushi

    2002-03-01

    It is very important both in medicine and biology to clarify the chromosomal structure to understand its functions. In a standard cytogenetic procedure, chromosomes are often fixed in a mixture of acetic acid and methanol. This process most likely changes the mechanical property of chromosomes. We adopted a method to prepare native and unfixed chromosomes from mouse 3T3 cells and used tapping and contact mode atomic force microscopy (AFM) to image and manipulate them. Modified AFM tips were used to image chromosomes in contact mode in air, and then the chromosome samples were immobilized on a substrate and placed in a buffer solution to pull out DNA-histone complexes from them after they were optimally treated with trypsin. From the AFM images, we could see several bands and granular structures on chromosomes. We obtained force curves indicating long fiber extensions from native chromosomes both with low (in high concentration of NaCl) and high forces (physiological conditions). The result suggested that the degree of chromosome condensation decreased in high concentration of salt. It agrees with the known fact of histone H1 dissociation in a high concentration of salt. We intend to pull out DNA-histone complexes from chromosomes for later molecular operations on them using an AFM.

  2. Hydrodynamic effects of the tip movement on surface nanobubbles: a combined tapping mode, lift mode and force volume mode AFM study.

    PubMed

    Walczyk, Wiktoria; Hain, Nicole; Schönherr, Holger

    2014-08-28

    We report on an Atomic Force Microscopy (AFM) study of AFM tip-nanobubble interactions in experiments conducted on argon surface nanobubbles on HOPG (highly oriented pyrolytic graphite) in water in tapping mode, lift mode and Force Volume (FV) mode AFM. By subsequent data acquisition on the same nanobubbles in these three different AFM modes, we could directly compare the effect of different tip-sample interactions. The tip-bubble interaction strength was found to depend on the vertical and horizontal position of the tip on the bubble with respect to the bubble center. The interaction forces measured experimentally were in good agreement with the forces calculated using the dynamic interaction model. The strength of the hydrodynamic effect was also found to depend on the direction of the tip movement. It was more pronounced in the FV mode, in which the tip approaches the bubble from the top, than in the lift mode, in which the tip approaches the bubble from the side. This result suggests that the direction of tip movement influences the bubble deformation. The effect should be taken into account when nanobubbles are analysed by AFM in various scanning modes. PMID:24988375

  3. Particle deformation induced by AFM tapping under different setpoint voltages

    NASA Astrophysics Data System (ADS)

    Wu, Chung-Lin; Farkas, Natalia; Dagata, John A.; He, Bo-Ching; Fu, Wei-En

    2014-09-01

    The measured height of polystyrene nanoparticles varies with setpoint voltage during atomic force microscopy (AFM) tapping-mode imaging. Nanoparticle height was strongly influenced by the magnitude of the deformation caused by the AFM tapping forces, which was determined by the setpoint voltage. This influence quantity was studied by controlling the operational AFM setpoint voltage. A test sample consisting of well-dispersed 60-nm polystyrene and gold nanoparticles co-adsorbed on poly-l-lysine-coated mica was studied in this research. Gold nanoparticles have not only better mechanical property than polystyrene nanoparticles, but also obvious facets in AFM phase image. By using this sample of mixed nanoparticles, it allows us to confirm that the deformation resulted from the effect of setpoint voltage, not noise. In tapping mode, the deformation of polystyrene nanoparticles increased with decreasing setpoint voltage. Similar behavior was observed with both open loop and closed loop AFM instruments.

  4. Combined scanning electrochemical atomic force microscopy for tapping mode imaging

    NASA Astrophysics Data System (ADS)

    Kueng, A.; Kranz, C.; Mizaikoff, B.; Lugstein, A.; Bertagnolli, E.

    2003-03-01

    With the integration of submicro- and nanoelectrodes into atomic force microscopy (AFM) tips using microfabrication techniques, an elegant approach combining scanning electrochemical microscopy (SECM) with atomic force microscopy has recently been demonstrated. Simultaneous imaging of topography and electrochemistry at a sample surface in AFM tapping mode with integrated SECM-AFM cantilevers oscillated at or near their resonance frequency is shown. In contrast to contact mode AFM imaging frictional forces at the sample surface are minimized. Hence, topographical and electrochemical information of soft surfaces (e.g., biological species) can be obtained.

  5. Nanomechanical basis for imaging soft materials with tapping mode atomic force microscopy

    SciTech Connect

    Howard, A.J.; Rye, R.R.; Houston, J.E.

    1996-02-01

    The surfaces of virgin and chemically etched poly(tetrafluoroethylene) (PTFE) have been studied using scanning electron microscopy (SEM), and atomic force microscopy (AFM) in both contact and tapping modes. Contact mode AFM images of this relatively soft polymeric material are dominated by tip-induced imaging artifacts. When subsequent, AFM imaging was performed in tapping mode these artifacts were eliminated, and comparable tapping mode AFM and SEM images were obtained for even the highly porous, unstable surface that results from sodium naphthalenide etching. Interfacial force microscopy force versus displacement, and creep experiments were performed to determine the nanomechanical nature of virgin PTFE. These experiments show that virgin PTFE is a viscoelastic material which is capable of supporting large forces on the millisecond time scale but creeps dramatically at longer times. Clearly, with scanning probe techniques which utilize constant probe force feedback, one should expect image distortions, as we observe, with soft materials such as virgin or etched PTFE. Conversely, with tapping mode AFM, rational images require contact times ({mu}s) that are much shorter than creep times (ms). Thus, viscoelastic material characteristics determine the need for tapping mode AFM over contact mode AFM. By comparing tapping mode AFM images of virgin and etched PTFE surfaces, we can understand the three-dimensional character of the etched surface necessary for mechanical interlocking and resultant strong metal adhesion.

  6. Self-oscillating tapping mode atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Manning, L.; Rogers, B.; Jones, M.; Adams, J. D.; Fuste, J. L.; Minne, S. C.

    2003-09-01

    A piezoelectric microcantilever probe is demonstrated as a self-oscillator used for tapping mode atomic force microscopy. The integrated piezoelectric film on the cantilever serves as the frequency-determining component of an oscillator circuit; oscillation near the cantilever's resonant frequency is maintained by applying positive feedback to the film via this circuit. This new mode, which is a step towards more compact and parallel tapping mode AFM imaging, is demonstrated by imaging an evaporated gold film on a silicon substrate. A self-oscillating frequency spectrum and a force-distance curve are also presented.

  7. Analysis of dynamic cantilever behavior in tapping mode atomic force microscopy.

    PubMed

    Deng, Wenqi; Zhang, Guang-Ming; Murphy, Mark F; Lilley, Francis; Harvey, David M; Burton, David R

    2015-10-01

    Tapping mode atomic force microscopy (AFM) provides phase images in addition to height and amplitude images. Although the behavior of tapping mode AFM has been investigated using mathematical modeling, comprehensive understanding of the behavior of tapping mode AFM still poses a significant challenge to the AFM community, involving issues such as the correct interpretation of the phase images. In this paper, the cantilever's dynamic behavior in tapping mode AFM is studied through a three dimensional finite element method. The cantilever's dynamic displacement responses are firstly obtained via simulation under different tip-sample separations, and for different tip-sample interaction forces, such as elastic force, adhesion force, viscosity force, and the van der Waals force, which correspond to the cantilever's action upon various different representative computer-generated test samples. Simulated results show that the dynamic cantilever displacement response can be divided into three zones: a free vibration zone, a transition zone, and a contact vibration zone. Phase trajectory, phase shift, transition time, pseudo stable amplitude, and frequency changes are then analyzed from the dynamic displacement responses that are obtained. Finally, experiments are carried out on a real AFM system to support the findings of the simulations. PMID:26303510

  8. Dynamic force microscopy simulator (dForce): A tool for planning and understanding tapping and bimodal AFM experiments.

    PubMed

    Guzman, Horacio V; Garcia, Pablo D; Garcia, Ricardo

    2015-01-01

    We present a simulation environment, dForce, which can be used for a better understanding of dynamic force microscopy experiments. The simulator presents the cantilever-tip dynamics for two dynamic AFM methods, tapping mode AFM and bimodal AFM. It can be applied for a wide variety of experimental situations in air or liquid. The code provides all the variables and parameters relevant in those modes, for example, the instantaneous deflection and tip-surface force, velocity, virial, dissipated energy, sample deformation and peak force as a function of time or distance. The simulator includes a variety of interactions and contact mechanics models to describe AFM experiments including: van der Waals, Hertz, DMT, JKR, bottom effect cone correction, linear viscoelastic forces or the standard linear solid viscoelastic model. We have compared two numerical integration methods to select the one that offers optimal accuracy and speed. The graphical user interface has been designed to facilitate the navigation of non-experts in simulations. Finally, the accuracy of dForce has been tested against numerical simulations performed during the last 18 years. PMID:25821676

  9. Dynamic force microscopy simulator (dForce): A tool for planning and understanding tapping and bimodal AFM experiments

    PubMed Central

    Guzman, Horacio V; Garcia, Pablo D

    2015-01-01

    Summary We present a simulation environment, dForce, which can be used for a better understanding of dynamic force microscopy experiments. The simulator presents the cantilever–tip dynamics for two dynamic AFM methods, tapping mode AFM and bimodal AFM. It can be applied for a wide variety of experimental situations in air or liquid. The code provides all the variables and parameters relevant in those modes, for example, the instantaneous deflection and tip–surface force, velocity, virial, dissipated energy, sample deformation and peak force as a function of time or distance. The simulator includes a variety of interactions and contact mechanics models to describe AFM experiments including: van der Waals, Hertz, DMT, JKR, bottom effect cone correction, linear viscoelastic forces or the standard linear solid viscoelastic model. We have compared two numerical integration methods to select the one that offers optimal accuracy and speed. The graphical user interface has been designed to facilitate the navigation of non-experts in simulations. Finally, the accuracy of dForce has been tested against numerical simulations performed during the last 18 years. PMID:25821676

  10. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy

    SciTech Connect

    Loganathan, Muthukumaran; Bristow, Douglas A.

    2014-04-15

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.

  11. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy.

    PubMed

    Loganathan, Muthukumaran; Bristow, Douglas A

    2014-04-01

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields. PMID:24784614

  12. RAPID COMMUNICATION: Frequency and force modulation atomic force microscopy: low-impact tapping-mode imaging without bistability

    NASA Astrophysics Data System (ADS)

    Solares, Santiago D.

    2007-07-01

    Since the 1980s, atomic force microscopy (AFM) has rapidly developed into a versatile, high-resolution characterization technique, available in a variety of imaging modes. Within intermittent-contact tapping-mode, imaging bistability and sample mechanical damage continue to be two of the most important challenges faced daily by AFM users. Recently, a new double-control-loop tapping-mode imaging algorithm (frequency and amplitude modulation AFM, FAM-AFM) was proposed and evaluated within numerical simulations, demonstrating a reduction in the repulsive tip sample forces and the absence of bistability. This article presents a much simpler algorithm, frequency and force modulation AFM (FFM-AFM), which requires only a single control loop and offers the same benefits as FAM-AFM. The concept is applied to calculate the cross-sectional scan of a carbon nanotube sample resting on a silicon surface, which is then compared to a previously reported image obtained in conventional amplitude-modulation tapping-mode, shown to be in agreement with the experimental result.

  13. Dynamics of the nanoneedle probe in trolling mode AFM.

    PubMed

    Abdi, Ahmad; Pishkenari, Hossein Nejat; Keramati, Ramtin; Minary-Jolandan, Majid

    2015-05-22

    Atomic force microscopy (AFM), as an indispensable tool for nanoscale characterization, presents major drawbacks for operation in a liquid environment arising from the large hydrodynamic drag on the vibrating cantilever. The newly introduced 'Trolling mode' (TR-mode) AFM resolves this complication by using a specialized nanoneedle cantilever that keeps the cantilever outside of the liquid. Herein, a mechanical model with a lumped mass was developed to capture the dynamics of such a cantilever with a nanoneedle tip. This new developed model was applied to investigate the effects of the needle-liquid interface on the performance of the AFM, including the imaging capability in liquid. PMID:25915451

  14. Tapping mode quartz crystal resonator based scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Seo, Yongho; Jhe, Wonho

    2005-01-01

    We have built a high-speed, tapping mode scanning force microscope using a high frequency quartz crystal resonator. In our design, a cantilever tip was attached to the end of an optical fiber which was glued to a thickness shear mode, AT-cut quartz crystal resonator so as to vibrate in the longitudinal direction. This design allows the microscope to be operated in tapping mode with the flexibility of shear mode operation, which leads to an expected improvement of image quality. Furthermore, combining this geometry with an optical microscope leads to the possibility of commercial applications.

  15. Topography imaging with a heated atomic force microscope cantilever in tapping mode

    SciTech Connect

    Park, Keunhan; Lee, Jungchul; Zhang, Zhuomin M.; King, William P.

    2007-04-15

    This article describes tapping mode atomic force microscopy (AFM) using a heated AFM cantilever. The electrical and thermal responses of the cantilever were investigated while the cantilever oscillated in free space or was in intermittent contact with a surface. The cantilever oscillates at its mechanical resonant frequency, 70.36 kHz, which is much faster than its thermal time constant of 300 {mu}s, and so the cantilever operates in thermal steady state. The thermal impedance between the cantilever heater and the sample was measured through the cantilever temperature signal. Topographical imaging was performed on silicon calibration gratings of height 20 and 100 nm. The obtained topography sensitivity is as high as 200 {mu}V/nm and the resolution is as good as 0.5 nm/Hz{sup 1/2}, depending on the cantilever power. The cantilever heating power ranges 0-7 mW, which corresponds to a temperature range of 25-700 deg. C. The imaging was performed entirely using the cantilever thermal signal and no laser or other optics was required. As in conventional AFM, the tapping mode operation demonstrated here can suppress imaging artifacts and enable imaging of soft samples.

  16. Investigation of temperature induced mechanical changes in supported bilayers by variants of tapping mode atomic force microscopy.

    PubMed

    Shamitko-Klingensmith, Nicole; Legleiter, Justin

    2015-01-01

    Tapping mode atomic force microscopy (AFM) is an invaluable technique for examining topographical features of biological materials in solution, and there has been a growing interest in developing techniques to provide further compositional contrast and information concerning surface mechanical properties. Phase shifts, cantilever response at higher harmonic frequencies of the drive, and time-resolved tip/sample force reconstruction have all been shown to provide additional compositional contrast of surfaces, as compared to basic tapping mode AFM imaging. This study aimed to demonstrate the relative ability of these different imaging techniques to detect temperature induced changes in the elastic modulus of supported total brain lipid extract (TBLE) bilayer patches on mica. To aid in direct comparison between the different imaging techniques, all required data was obtained simultaneously while capturing traditional tapping mode AFM topography images. While all of the techniques were able to provide compositional contrast consistent with known temperature-induced changes in the bilayer patch, interpretation of the resulting contrast was not always straightforward. Phase imaging suffered from contrast inversion. Individual harmonics responded in a variety of ways to the temperature-induced changes in elastic modulus of the bilayer. The maximum tapping force (or peak force) associated with imaging the bilayer correctly reflected the changes in elastic modulus of the lipid bilayer. Importantly, as the required data can be obtained simultaneously, combining these different imaging techniques can lead to a more complete understanding of a sample's mechanical features. PMID:25369473

  17. Viscoelasticity of living cells allows high resolution imaging by tapping mode atomic force microscopy.

    PubMed

    Putman, C A; van der Werf, K O; de Grooth, B G; van Hulst, N F; Greve, J

    1994-10-01

    Application of atomic force microscopy (AFM) to biological objects and processes under physiological conditions has been hampered so far by the deformation and destruction of the soft biological materials invoked. Here we describe a new mode of operation in which the standard V-shaped silicon nitride cantilever is oscillated under liquid and damped by the interaction between AFM tip and sample surface. Because of the viscoelastic behavior of the cellular surface, cells effectively "harden" under such a tapping motion at high frequencies and become less susceptible to deformation. Images obtained in this way primarily reveal the surface structure of the cell. It is now possible to study physiological processes, such as cell growth, with a minimal level of perturbation and high spatial resolution (approximately 20 nm). PMID:7819507

  18. Accurate force spectroscopy in tapping mode atomic force microscopy in liquids

    NASA Astrophysics Data System (ADS)

    Xu, Xin; Melcher, John; Raman, Arvind

    2010-01-01

    Existing force spectroscopy methods in tapping mode atomic force microscopy (AFM) such as higher harmonic inversion [M. Stark, R. W. Stark, W. M. Heckl, and R. Guckenberger, Proc. Natl. Acad. Sci. U.S.A. 99, 8473 (2002)] or scanning probe acceleration microscopy [J. Legleiter, M. Park, B. Cusick, and T. Kowalewski, Proc. Natl. Acad. Sci. U.S.A. 103, 4813 (2006)] or integral relations [M. Lee and W. Jhe, Phys. Rev. Lett. 97, 036104 (2006); S. Hu and A. Raman, Nanotechnology 19, 375704 (2008); H. Hölscher, Appl. Phys. Lett. 89, 123109 (2006); A. J. Katan, Nanotechnology 20, 165703 (2009)] require and assume as an observable the tip dynamics in a single eigenmode of the oscillating microcantilever. We demonstrate that this assumption can distort significantly the extracted tip-sample interaction forces when applied to tapping mode AFM with soft cantilevers in liquid environments. This exception is due to the fact that under these conditions the second eigenmode is momentarily excited and the observed tip dynamics clearly contains contributions from the fundamental and second eigenmodes. To alleviate this problem, a simple experimental method is proposed to screen the second eigenmode contributions in the observed tip deflection signal to allow accurate tip-sample force reconstruction in liquids. The method is implemented experimentally to reconstruct interaction forces on polymer, bacteriorhodopsin membrane, and mica samples in buffer solutions.

  19. High-speed tapping-mode atomic force microscopy using a Q-controlled regular cantilever acting as the actuator: Proof-of-principle experiments

    SciTech Connect

    Balantekin, M.; Satır, S.; Torello, D.; Değertekin, F. L.

    2014-12-15

    We present the proof-of-principle experiments of a high-speed actuation method to be used in tapping-mode atomic force microscopes (AFM). In this method, we do not employ a piezotube actuator to move the tip or the sample as in conventional AFM systems, but, we utilize a Q-controlled eigenmode of a cantilever to perform the fast actuation. We show that the actuation speed can be increased even with a regular cantilever.

  20. Force reconstruction from tapping mode force microscopy experiments

    NASA Astrophysics Data System (ADS)

    Payam, Amir F.; Martin-Jimenez, Daniel; Garcia, Ricardo

    2015-05-01

    Fast, accurate, and robust nanomechanical measurements are intensely studied in materials science, applied physics, and molecular biology. Amplitude modulation force microscopy (tapping mode) is the most established nanoscale characterization technique of surfaces for air and liquid environments. However, its quantitative capabilities lag behind its high spatial resolution and robustness. We develop a general method to transform the observables into quantitative force measurements. The force reconstruction algorithm has been deduced on the assumption that the observables (amplitude and phase shift) are slowly varying functions of the tip-surface separation. The accuracy and applicability of the method is validated by numerical simulations and experiments. The method is valid for liquid and air environments, small and large free amplitudes, compliant and rigid materials, and conservative and non-conservative forces.

  1. A control approach to cross-coupling compensation of piezotube scanners in tapping-mode atomic force microscope imaging

    NASA Astrophysics Data System (ADS)

    Wu, Ying; Shi, Jian; Su, Chanmin; Zou, Qingze

    2009-04-01

    In this article, an approach based on the recently developed inversion-based iterative control (IIC) to cancel the cross-axis coupling effect of piezoelectric tube scanners (piezoscanners) in tapping-mode atomic force microscope (AFM) imaging is proposed. Cross-axis coupling effect generally exists in piezoscanners used for three-dimensional (x-y-z axes) nanopositioning in applications such as AFM, where the vertical z-axis movement can be generated by the lateral x-y axes scanning. Such x /y-to-z cross-coupling becomes pronounced when the scanning is at large range and/or at high speed. In AFM applications, the coupling-caused position errors, when large, can generate various adverse effects, including large imaging and topography distortions, and damage of the cantilever probe and/or the sample. This paper utilizes the IIC technique to obtain the control input to precisely track the coupling-caused x /y-to-z displacement (with sign-flipped). Then the obtained input is augmented as a feedforward control to the existing feedback control in tapping-mode imaging, resulting in the cancellation of the coupling effect. The proposed approach is illustrated through two exemplary applications in industry, the pole-tip recession examination, and the nanoasperity measurement on hard-disk drive. Experimental results show that the x /y-to-z coupling effect in large-range (20 and 45 μm) tapping-mode imaging at both low to high scan rates (2, 12.2 to 24.4 Hz) can be effectively removed.

  2. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    PubMed Central

    2015-01-01

    Summary This paper introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretation of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tapping-mode imaging, for both of which the force curves exhibit the expected features. Finally, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments. PMID:26734515

  3. The nanoscale phase distinguishing of PCL-PB-PCL blended in epoxy resin by tapping mode atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Li, Huiqin; Sun, Limin; Shen, Guangxia; Liang, Qi

    2012-02-01

    In this work, we investigated the bulk phase distinguishing of the poly(ɛ-caprolactone)-polybutadiene-poly(ɛ-caprolactone) (PCL-PB-PCL) triblock copolymer blended in epoxy resin by tapping mode atomic force microscopy (TM-AFM). We found that at a set-point amplitude ratio ( r sp) less than or equal to 0.85, a clear phase contrast could be obtained using a probe with a force constant of 40 N/m. When r sp was decreased to 0.1 or less, the measured size of the PB-rich domain relatively shrank; however, the height images of the PB-rich domain would take reverse (translating from the original light to dark) at r sp = 0.85. Force-probe measurements were carried out on the phase-separated regions by TM-AFM. According to the phase shift angle vs. r sp curve, it could be concluded that the different force exerting on the epoxy matrix or on the PB-rich domain might result in the height and phase image reversion. Furthermore, the indentation depth vs. r sp plot showed that with large tapping force (lower r sp), the indentation depth for the PB-rich domain was nearly identical for the epoxy resin matrix.

  4. The nanoscale phase distinguishing of PCL-PB-PCL blended in epoxy resin by tapping mode atomic force microscopy

    PubMed Central

    2012-01-01

    In this work, we investigated the bulk phase distinguishing of the poly(ε-caprolactone)-polybutadiene-poly(ε-caprolactone) (PCL-PB-PCL) triblock copolymer blended in epoxy resin by tapping mode atomic force microscopy (TM-AFM). We found that at a set-point amplitude ratio (rsp) less than or equal to 0.85, a clear phase contrast could be obtained using a probe with a force constant of 40 N/m. When rsp was decreased to 0.1 or less, the measured size of the PB-rich domain relatively shrank; however, the height images of the PB-rich domain would take reverse (translating from the original light to dark) at rsp = 0.85. Force-probe measurements were carried out on the phase-separated regions by TM-AFM. According to the phase shift angle vs. rsp curve, it could be concluded that the different force exerting on the epoxy matrix or on the PB-rich domain might result in the height and phase image reversion. Furthermore, the indentation depth vs. rsp plot showed that with large tapping force (lower rsp), the indentation depth for the PB-rich domain was nearly identical for the epoxy resin matrix. PMID:22360980

  5. The formation of liquid bridge in different operating modes of AFM

    NASA Astrophysics Data System (ADS)

    Wei, Zheng; Sun, Yan; Ding, WenXuan; Wang, ZaiRan

    2016-09-01

    The liquid bridge is one of the principal factors that cause artifacts in ambient-pressure atomic force microscope (AFM) images. Additionally, it is the main component of the adhesion force in ambient conditions. To understand the AFM imaging mechanism and the sample characteristics, it is essential to study the liquid bridge. This study interprets the physical mechanism involved in liquid bridge formation, which is composed of three different physical processes: the squeezing process, capillary condensation, and liquid film flow. We discuss the contributions of these three mechanisms to the volume and the capillary force of the liquid bridge in different AFM operation modes.

  6. Improvement of tapping-mode scanning near-field optical microscope

    NASA Astrophysics Data System (ADS)

    Zhuo, Wenjiang; Li, Qin; Sun, Jialin; Xu, Jianhua; Zhao, Jun; Guo, Jihua

    2000-10-01

    The commercial crystal tuning fork glued with an optical fiber probe is used as the sensitive detecting element for the tapping-mode scanning near-field optical microscopy. Firstly, the single-mode optical fiber is etched down to a small diameter to decrease the burden of the tuning fork. Secondary, the fiber is etched for the second time to form the sharp tip with large cone angle. Thirdly, the fiber probe, with nanometric tip and high light throughput, is glued to tuning fork by Cyanoacrylate Adhesive. The measured quality factor, Q, of the tuning fork/optical fiber probe assembly prepared in this way is higher than 300. The optical signal is modulated to the frequency of the tuning fork by optical fiber probe as it is detecting the topography of sample. The high-resolution of the tapping- mode detector is proved by imaging the topography of the grating and biological cell.

  7. Tip Effect of the Tapping Mode of Atomic Force Microscope in Viscous Fluid Environments.

    PubMed

    Shih, Hua-Ju; Shih, Po-Jen

    2015-01-01

    Atomic force microscope with applicable types of operation in a liquid environment is widely used to scan the contours of biological specimens. The contact mode of operation allows a tip to touch a specimen directly but sometimes it damages the specimen; thus, a tapping mode of operation may replace the contact mode. The tapping mode triggers the cantilever of the microscope approximately at resonance frequencies, and so the tip periodically knocks the specimen. It is well known that the cantilever induces extra liquid pressure that leads to drift in the resonance frequency. Studies have noted that the heights of protein surfaces measured via the tapping mode of an atomic force microscope are ~25% smaller than those measured by other methods. This discrepancy may be attributable to the induced superficial hydrodynamic pressure, which is worth investigating. In this paper, we introduce a semi-analytical method to analyze the pressure distribution of various tip geometries. According to our analysis, the maximum hydrodynamic pressure on the specimen caused by a cone-shaped tip is ~0.5 Pa, which can, for example, pre-deform a cell by several nanometers in compression before the tip taps it. Moreover, the pressure calculated on the surface of the specimen is 20 times larger than the pressure without considering the tip effect; these results have not been motioned in other papers. Dominating factors, such as surface heights of protein surface, mechanical stiffness of protein increasing with loading velocity, and radius of tip affecting the local pressure of specimen, are also addressed in this study. PMID:26225979

  8. APOBEC3G Interacts with ssDNA by Two Modes: AFM Studies

    NASA Astrophysics Data System (ADS)

    Shlyakhtenko, Luda S.; Dutta, Samrat; Banga, Jaspreet; Li, Ming; Harris, Reuben S.; Lyubchenko, Yuri L.

    2015-10-01

    APOBEC3G (A3G) protein has antiviral activity against HIV and other pathogenic retroviruses. A3G has two domains: a catalytic C-terminal domain (CTD) that deaminates cytidine, and a N-terminal domain (NTD) that binds to ssDNA. Although abundant information exists about the biological activities of A3G protein, the interplay between sequence specific deaminase activity and A3G binding to ssDNA remains controversial. We used the topographic imaging and force spectroscopy modalities of Atomic Force Spectroscopy (AFM) to characterize the interaction of A3G protein with deaminase specific and nonspecific ssDNA substrates. AFM imaging demonstrated that A3G has elevated affinity for deaminase specific ssDNA than for nonspecific ssDNA. AFM force spectroscopy revealed two distinct binding modes by which A3G interacts with ssDNA. One mode requires sequence specificity, as demonstrated by stronger and more stable complexes with deaminase specific ssDNA than with nonspecific ssDNA. Overall these observations enforce prior studies suggesting that both domains of A3G contribute to the sequence specific binding of ssDNA.

  9. Analytical evaluation of describing functions arising from harmonic balance analysis of tapping mode atomic force microscope.

    PubMed

    Mamedov, B A

    2008-05-01

    A new algorithm of harmonic balance analysis of tapping mode atomic force microscopes has been developed. The new algorithm is applicable to analytical evaluation of a large class of common tip-sample interaction potentials. The extensive test calculations show that the proposed algorithm in this work is the efficient one in practical computations. The comparative values presented in tables are acceptable and have the excellent agreement with the numerical results. PMID:18513097

  10. Direct measurement of optical force induced by near-field plasmonic cavity using dynamic mode AFM

    SciTech Connect

    Guan, Dongshi; Hang, Zhi Hong; Marset, Zsolt; Liu, Hui; Kravchenko, Ivan I.; Chan, Ho Bun; Chan, C. T.; Tong, Penger

    2015-11-20

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. Lastly, the experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.

  11. Direct measurement of optical force induced by near-field plasmonic cavity using dynamic mode AFM

    DOE PAGESBeta

    Guan, Dongshi; Hang, Zhi Hong; Marset, Zsolt; Liu, Hui; Kravchenko, Ivan I.; Chan, Ho Bun; Chan, C. T.; Tong, Penger

    2015-11-20

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength goldmore » disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. Lastly, the experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.« less

  12. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM.

    PubMed

    Guan, Dongshi; Hang, Zhi Hong; Marcet, Zsolt; Liu, Hui; Kravchenko, I I; Chan, C T; Chan, H B; Tong, Penger

    2015-01-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. The experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures. PMID:26586455

  13. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM

    PubMed Central

    Guan, Dongshi; Hang, Zhi Hong; Marcet, Zsolt; Liu, Hui; Kravchenko, I. I.; Chan, C. T.; Chan, H. B.; Tong, Penger

    2015-01-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. The experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures. PMID:26586455

  14. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM

    NASA Astrophysics Data System (ADS)

    Guan, Dongshi; Hang, Zhi Hong; Marcet, Zsolt; Liu, Hui; Kravchenko, I. I.; Chan, C. T.; Chan, H. B.; Tong, Penger

    2015-11-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. The experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.

  15. Analyzing the Effect of Capillary Force on Vibrational Performance of the Cantilever of an Atomic Force Microscope in Tapping Mode with Double Piezoelectric Layers in an Air Environment.

    PubMed

    Nahavandi, Amir; Korayem, Moharam Habibnejad

    2015-10-01

    The aim of this paper is to determine the effects of forces exerted on the cantilever probe tip of an atomic force microscope (AFM). These forces vary according to the separation distance between the probe tip and the surface of the sample being examined. Hence, at a distance away from the surface (farther than d(on)), these forces have an attractive nature and are of Van der Waals type, and when the probe tip is situated in the range of a₀≤ d(ts) ≤ d(on), the capillary force is added to the Van der Waals force. At a distance of d(ts) ≤ a₀, the Van der Waals and capillary forces remain constant at intermolecular distances, and the contact repulsive force repels the probe tip from the surface of sample. The capillary force emerges due to the contact of thin water films with a thickness of h(c) which have accumulated on the sample and probe. Under environmental conditions a layer of water or hydrocarbon often forms between the probe tip and sample. The capillary meniscus can grow until the rate of evaporation equals the rate of condensation. For each of the above forces, different models are presented. The smoothness or roughness of the surfaces and the geometry of the cantilever tip have a significant effect on the modeling of forces applied on the probe tip. Van der Waals and the repulsive forces are considered to be the same in all the simulations, and only the capillary force is altered in order to evaluate the role of this force in the AFM-based modeling. Therefore, in view of the remarkable advantages of the piezoelectric microcantilever and also the extensive applications of the tapping mode, we investigate vibrational motion of the piezoelectric microcantilever in the tapping mode. The cantilever mentioned is entirely covered by two piezoelectric layers that carry out both the actuation of the probe tip and the measuringof its position. PMID:26324257

  16. A novel self-sensing technique for tapping-mode atomic force microscopy

    SciTech Connect

    Ruppert, Michael G.; Moheimani, S. O. Reza

    2013-12-15

    This work proposes a novel self-sensing tapping-mode atomic force microscopy operation utilizing charge measurement. A microcantilever coated with a single piezoelectric layer is simultaneously used for actuation and deflection sensing. The cantilever can be batch fabricated with existing micro electro mechanical system processes. The setup enables the omission of the optical beam deflection technique which is commonly used to measure the cantilever oscillation amplitude. Due to the high amount of capacitive feedthrough in the measured charge signal, a feedforward control technique is employed to increase the dynamic range from less than 1 dB to approximately 35 dB. Experiments show that the conditioned charge signal achieves excellent signal-to-noise ratio and can therefore be used as a feedback signal for atomic force microscopy imaging.

  17. A novel self-sensing technique for tapping-mode atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Ruppert, Michael G.; Moheimani, S. O. Reza

    2013-12-01

    This work proposes a novel self-sensing tapping-mode atomic force microscopy operation utilizing charge measurement. A microcantilever coated with a single piezoelectric layer is simultaneously used for actuation and deflection sensing. The cantilever can be batch fabricated with existing micro electro mechanical system processes. The setup enables the omission of the optical beam deflection technique which is commonly used to measure the cantilever oscillation amplitude. Due to the high amount of capacitive feedthrough in the measured charge signal, a feedforward control technique is employed to increase the dynamic range from less than 1 dB to approximately 35 dB. Experiments show that the conditioned charge signal achieves excellent signal-to-noise ratio and can therefore be used as a feedback signal for atomic force microscopy imaging.

  18. A novel self-sensing technique for tapping-mode atomic force microscopy.

    PubMed

    Ruppert, Michael G; Moheimani, S O Reza

    2013-12-01

    This work proposes a novel self-sensing tapping-mode atomic force microscopy operation utilizing charge measurement. A microcantilever coated with a single piezoelectric layer is simultaneously used for actuation and deflection sensing. The cantilever can be batch fabricated with existing micro electro mechanical system processes. The setup enables the omission of the optical beam deflection technique which is commonly used to measure the cantilever oscillation amplitude. Due to the high amount of capacitive feedthrough in the measured charge signal, a feedforward control technique is employed to increase the dynamic range from less than 1 dB to approximately 35 dB. Experiments show that the conditioned charge signal achieves excellent signal-to-noise ratio and can therefore be used as a feedback signal for atomic force microscopy imaging. PMID:24387461

  19. Tip-sample interaction in tapping-mode scanning force microscopy

    NASA Astrophysics Data System (ADS)

    de Pablo, P. J.; Colchero, J.; Luna, M.; Gómez-Herrero, J.; Baró, A. M.

    2000-05-01

    Tip-sample interaction in intermittent contact scanning force microscopy, also called tapping mode, is experimentally studied to determine under which conditions tip-sample contact is established. Force vs distance curves are made while the cantilever is oscillating at its resonance frequency. Cantilevers with different force constants driven at different oscillation amplitudes have been used. In addition, samples with different hardness, such as silicon oxide, glass, and highly orientated pyrolytic graphite were taken as sample surface. From the analysis of the data we conclude that by choosing appropriate operating conditions, tip-sample contact can be avoided. This operating regime is of general interest in scanning force microscopy, since it allows imaging of even the softest samples.

  20. Imaging resolution of AFM with probes modified with FIB.

    PubMed

    Skibinski, J; Rebis, J; Wejrzanowski, T; Rozniatowski, K; Pressard, K; Kurzydlowski, K J

    2014-11-01

    This study concerns imaging of the structure of materials using AFM tapping (TM) and phase imaging (PI) mode, using probes modified with focused ion beam (FIB). Three kinds of modifications were applied - thinning of the cantilever, sharpening of the tip and combination of these two modifications. Probes shaped in that way were used for AFM investigations with Bruker AFM Nanoscope 8. As a testing material, titanium roughness standard supplied by Bruker was used. The results show that performed modifications influence the oscillation of the probes. In particular thinning of the cantilever enables one to acquire higher self-resonant frequencies, which can be advantageous for improving the quality of imaging in PI mode. It was found that sharpening the tip improves imaging resolution in tapping mode, which is consistent with existing knowledge, but lowered the quality of high frequency topography images. In this paper the Finite Element Method (FEM) was used to explain the results obtained experimentally. PMID:25080273

  1. Haitian Tap-Taps

    ERIC Educational Resources Information Center

    Sterling, Joan

    2011-01-01

    In the small island country of Haiti, colorful taxis transport the natives to the market. Although the taxis may be crowded with people, goods, and even livestock, it is considered a luxury to ride rather than go on foot. The children's picture book, "Tap-Tap," is a wonderful introduction to the culture of this land. The name "tap-tap" is derived…

  2. Parameter sensitivity analysis of nonlinear piezoelectric probe in tapping mode atomic force microscopy for measurement improvement

    SciTech Connect

    McCarty, Rachael; Nima Mahmoodi, S.

    2014-02-21

    The equations of motion for a piezoelectric microcantilever are derived for a nonlinear contact force. The analytical expressions for natural frequencies and mode shapes are obtained. Then, the method of multiple scales is used to analyze the analytical frequency response of the piezoelectric probe. The effects of nonlinear excitation force on the microcantilever beam's frequency and amplitude are analytically studied. The results show a frequency shift in the response resulting from the force nonlinearities. This frequency shift during contact mode is an important consideration in the modeling of AFM mechanics for generation of more accurate imaging. Also, a sensitivity analysis of the system parameters on the nonlinearity effect is performed. The results of a sensitivity analysis show that it is possible to choose parameters such that the frequency shift minimizes. Certain parameters such as tip radius, microcantilever beam dimensions, and modulus of elasticity have more influence on the nonlinearity of the system than other parameters. By changing only three parameters—tip radius, thickness, and modulus of elasticity of the microbeam—a more than 70% reduction in nonlinearity effect was achieved.

  3. Application of Tapping-Mode Scanning Probe Electrospray Ionization to Mass Spectrometry Imaging of Additives in Polymer Films

    PubMed Central

    Shimazu, Ryo; Yamoto, Yoshinari; Kosaka, Tomoya; Kawasaki, Hideya; Arakawa, Ryuichi

    2014-01-01

    We report the application of tapping-mode scanning probe electrospray ionization (t-SPESI) to mass spectrometry imaging of industrial materials. The t-SPESI parameters including tapping solvent composition, solvent flow rate, number of tapping at each spot, and step-size were optimized using a quadrupole mass spectrometer to improve mass spectrometry (MS) imaging of thin-layer chromatography (TLC) and additives in polymer films. Spatial resolution of approximately 100 μm was achieved by t-SPESI imaging mass spectrometry using a fused-silica capillary (50 μm i.d., 150 μm o.d.) with the flow rate set at 0.2 μL/min. This allowed us to obtain discriminable MS imaging profiles of three dyes separated by TLC and the additive stripe pattern of a PMMA model film depleted by UV irradiation. PMID:26819894

  4. AFM PeakForce QNM mode: Evidencing nanometre-scale mechanical properties of chitin-silica hybrid nanocomposites.

    PubMed

    Smolyakov, G; Pruvost, S; Cardoso, L; Alonso, B; Belamie, E; Duchet-Rumeau, J

    2016-10-20

    PeakForce Quantitative Nanomechanical Mapping (QNM) AFM mode was used to explore the mechanical properties of textured chitin-silica hybrid films at the nanoscale. The influence of the force applied by the tip on the sample surface was studied for standard homogeneous samples, for chitin nanorods and for chitin-silica hybrid nanocomposites. Thick films of superimposed chitin nanorods showed a monotonous increase of DMT modulus (based on the Derjaguin-Muller-Toporov model) owing to an increase in modulus at the interface between nanorods due to geometrical constraints of the AFM acquisition. A similar variation of DMT modulus was obtained for chitin-silica hybrid thick films related to mechanical strengthening induced by the presence of silica. This work revealed the role of the organic-inorganic interface, at the nanoscale, in the mechanical behaviour of textured materials using PeakForce QNM mode, with optimized analysis conditions. PMID:27474579

  5. Personal electronics printing via tapping mode composite liquid metal ink delivery and adhesion mechanism.

    PubMed

    Zheng, Yi; He, Zhi-Zhu; Yang, Jun; Liu, Jing

    2014-01-01

    Printed electronics is becoming increasingly important in a variety of newly emerging areas. However, restricted to the rather limited conductive inks and available printing strategies, the current electronics manufacture is usually confined to industry level. Here, we show a highly cost-effective and entirely automatic printing way towards personal electronics making, through introducing a tapping-mode composite fluid delivery system. Fundamental mechanisms regarding the reliable printing, transfer and adhesion of the liquid metal inks on the substrate were disclosed through systematic theoretical interpretation and experimental measurements. With this liquid metal printer, a series of representative electronic patterns spanning from single wires to desired complex configurations such as integrated circuit (IC), printed-circuits-on-board (PCB), electronic paintings, or more do-it-yourself (DIY) devices, were demonstrated to be printed out with high precision in a moment. And the total machine cost already reached personally affordable price. This is hard to achieve by a conventional PCB technology which generally takes long time and is material, water and energy consuming, while the existing printed electronics is still far away from the real direct printing goal. The present work opens the way for large scale personal electronics manufacture and is expected to generate important value for the coming society. PMID:24699375

  6. Personal electronics printing via tapping mode composite liquid metal ink delivery and adhesion mechanism

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; He, Zhi-Zhu; Yang, Jun; Liu, Jing

    2014-04-01

    Printed electronics is becoming increasingly important in a variety of newly emerging areas. However, restricted to the rather limited conductive inks and available printing strategies, the current electronics manufacture is usually confined to industry level. Here, we show a highly cost-effective and entirely automatic printing way towards personal electronics making, through introducing a tapping-mode composite fluid delivery system. Fundamental mechanisms regarding the reliable printing, transfer and adhesion of the liquid metal inks on the substrate were disclosed through systematic theoretical interpretation and experimental measurements. With this liquid metal printer, a series of representative electronic patterns spanning from single wires to desired complex configurations such as integrated circuit (IC), printed-circuits-on-board (PCB), electronic paintings, or more do-it-yourself (DIY) devices, were demonstrated to be printed out with high precision in a moment. And the total machine cost already reached personally affordable price. This is hard to achieve by a conventional PCB technology which generally takes long time and is material, water and energy consuming, while the existing printed electronics is still far away from the real direct printing goal. The present work opens the way for large scale personal electronics manufacture and is expected to generate important value for the coming society.

  7. Personal electronics printing via tapping mode composite liquid metal ink delivery and adhesion mechanism

    PubMed Central

    Zheng, Yi; He, Zhi-Zhu; Yang, Jun; Liu, Jing

    2014-01-01

    Printed electronics is becoming increasingly important in a variety of newly emerging areas. However, restricted to the rather limited conductive inks and available printing strategies, the current electronics manufacture is usually confined to industry level. Here, we show a highly cost-effective and entirely automatic printing way towards personal electronics making, through introducing a tapping-mode composite fluid delivery system. Fundamental mechanisms regarding the reliable printing, transfer and adhesion of the liquid metal inks on the substrate were disclosed through systematic theoretical interpretation and experimental measurements. With this liquid metal printer, a series of representative electronic patterns spanning from single wires to desired complex configurations such as integrated circuit (IC), printed-circuits-on-board (PCB), electronic paintings, or more do-it-yourself (DIY) devices, were demonstrated to be printed out with high precision in a moment. And the total machine cost already reached personally affordable price. This is hard to achieve by a conventional PCB technology which generally takes long time and is material, water and energy consuming, while the existing printed electronics is still far away from the real direct printing goal. The present work opens the way for large scale personal electronics manufacture and is expected to generate important value for the coming society. PMID:24699375

  8. Controlled-Resonant Surface Tapping-Mode Scanning Probe Electrospray Ionization Mass Spectrometry Imaging

    SciTech Connect

    Lorenz, Matthias; Ovchinnikova, Olga S; Kertesz, Vilmos; Van Berkel, Gary J

    2014-01-01

    This paper reports on the advancement of a controlled-resonance surface tapping-mode single capillary liquid junction extraction/ESI emitter for mass spectrometry imaging. The basic instrumental setup and the general operation of the system were discussed and optimized performance metrics were presented. The ability to spot sample, lane scan and chemically image in an automated and controlled fashion were demonstrated. Rapid, automated spot sampling was demonstrated for a variety of compound types including the cationic dye basic blue 7, the oligosaccharide cellopentaose, and the protein equine heart cytochrome c. The system was used for lane scanning and chemical imaging of the cationic dye crystal violet in inked lines on glass and for lipid distributions in mouse brain thin tissue sections. Imaging of the lipids in mouse brain tissue under optimized conditions provided a spatial resolution of approximately 35 m based on the ability to distinguish between features observed both in the optical and mass spectral chemical images. The sampling spatial resolution of this system was comparable to the best resolution that has been reported for other types of atmospheric pressure liquid extraction-based surface sampling/ionization techniques used for mass spectrometry imaging.

  9. Atomic force microscope nanolithography: dip-pen, nanoshaving, nanografting, tapping mode, electrochemical and thermal nanolithography.

    PubMed

    Rosa, Luis G; Liang, Jian

    2009-12-01

    Atomic force microscopy (AFM) has been widely employed as a nanoscopic lithography technique. In this review, we summarize the current state of research in this field. We introduce the various forms of the technique, such as nanoshaving, nanografting and dip-pen nanolithography, which we classify according to the different interactions between the AFM probe and the substrate during the nanolithography fabrication process. Mechanical force, applied by the tip to the substrate, is the variable that can be controlled with good precision in AFM and it has been utilized in patterning self-assembled monolayers. In such applications, the AFM tip can break some relatively weak chemical bonds inside the monolayer. In general, the state of the art for AFM nanolithography demonstrates the power, resolution and versatility of the technique. PMID:21832507

  10. Dielectric charging by AFM in tip-to-sample space mode: overview and challenges in revealing the appropriate mechanisms.

    PubMed

    Makasheva, K; Villeneuve-Faure, C; Laurent, C; Despax, B; Boudou, L; Teyssedre, G

    2015-07-24

    The study of charge distribution on the surface and in the bulk of dielectrics is of great scientific interest because of the information gained on the storage and transport properties of the medium. Nevertheless, the processes at the nanoscale level remain out of the scope of the commonly used diagnostic methods. Atomic force microscopy (AFM) is currently applied for both injection and imaging of charges on dielectric thin films at the nanoscale level to answer the increasing demand for characterization of miniaturized components used in microelectronics, telecommunications, electrophotography, electrets, etc. However, the mechanisms for dielectric charging by AFM are not well documented, and an analysis of the literature shows that inappropriate mechanisms are sometimes presented. It is shown here that corona discharge, frequently pointed out as a likely mechanism for dielectric charging by AFM in tip-to-sample space mode, cannot develop in such small distances. Furthermore, a review of different mechanisms surmised to be at the origin of dielectric charging at the nanoscale level is offered. Field electron emission enhanced by thermionic emission is identified as a likely mechanism for dielectric charging at the nanoscale level. Experimental validation of this mechanism is obtained for typical electric field strengths in AFM. PMID:26133237

  11. Dielectric charging by AFM in tip-to-sample space mode: overview and challenges in revealing the appropriate mechanisms

    NASA Astrophysics Data System (ADS)

    Makasheva, K.; Villeneuve-Faure, C.; Laurent, C.; Despax, B.; Boudou, L.; Teyssedre, G.

    2015-07-01

    The study of charge distribution on the surface and in the bulk of dielectrics is of great scientific interest because of the information gained on the storage and transport properties of the medium. Nevertheless, the processes at the nanoscale level remain out of the scope of the commonly used diagnostic methods. Atomic force microscopy (AFM) is currently applied for both injection and imaging of charges on dielectric thin films at the nanoscale level to answer the increasing demand for characterization of miniaturized components used in microelectronics, telecommunications, electrophotography, electrets, etc. However, the mechanisms for dielectric charging by AFM are not well documented, and an analysis of the literature shows that inappropriate mechanisms are sometimes presented. It is shown here that corona discharge, frequently pointed out as a likely mechanism for dielectric charging by AFM in tip-to-sample space mode, cannot develop in such small distances. Furthermore, a review of different mechanisms surmised to be at the origin of dielectric charging at the nanoscale level is offered. Field electron emission enhanced by thermionic emission is identified as a likely mechanism for dielectric charging at the nanoscale level. Experimental validation of this mechanism is obtained for typical electric field strengths in AFM.

  12. Investigation of bacterial-mineral interactions using Fluid Tapping Mode ™ Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Grantham, Meg C.; Dove, Patricia M.

    1996-07-01

    Bacterial adhesion to the porous media of subsurface environments and their mobility through these systems are of interest in biogeochemistry. Dissimilatory reducing bacteria can be major contributors to good or poor water quality due to their ability to catalyze sulfate and iron reduction as well as denitrification reactions. Advances in Fluid Cell Tapping Mode ™ Atomic Force Microscopy (Fluid TMAFM) make it possible to better understand these natural phenomena through direct observations of live bacteria-mineral surface interactions. This study used Fluid TMAFM to investigate the effect of iron coatings on the interactions of Shewanella putrefaciens with silica glass surfaces (as analogues for quartz). S. putrefaciens are facultative anaerobic dissimilatory Fe-reducing bacteria that are closely related to Pseudomonas spp. These were seeded onto ferric iron oxyhydroxide coated (Fe-coated) and uncoated silica glass substrates in aqueous solutions of varying nutrient composition and incubated under aerobic conditions for 1-4 days. Seeded and control surfaces were examined using Air and Fluid TMAFM. Observations of live bacteria-surface interactions found that bacteria in nutrient-depleted solutions adhered to Fe-coated substrates more strongly than bacteria seeded in nutrient-rich solutions. Under nutrient-limited conditions, the adhered bacteria corrode the iron coating to form bacteria-shaped depressions within 3 days of exposure. As much as 10% of the iron coatings were mobilized. Also, they adhered more strongly to Fe-coated than uncoated silica glass. Bacteria seeded in nutrient-enriched solutions were mostly flagellated suggesting that motility and adhesion are related. These findings suggest that adhesion, motility, and iron surface chemistry are interrelated in subsurface environments where Fe-reducing microorganisms are present.

  13. Mode coupling in a hanging-fiber AFM used as a rheological probe

    NASA Astrophysics Data System (ADS)

    Devailly, C.; Laurent, J.; Steinberger, A.; Bellon, L.; Ciliberto, S.

    2014-06-01

    We analyze the advantages and drawbacks of a method which measures the viscosity of liquids at microscales, using a thin glass fiber fixed on the tip of a cantilever of an ultra-low-noise Atomic Force Microscope (AFM). When the fiber is dipped into a liquid, the dissipation of the cantilever-fiber system, which is linked to the liquid viscosity, can be computed from the power spectral density of the thermal fluctuations of the cantilever deflection. The high sensitivity of the AFM allows us to show the existence and to develop a model of the coupling between the dynamics of the fiber and that of the cantilever. This model, which accurately fits the experimental data, gives also more insights into the dynamics of coupled microdevices in a viscous environment.

  14. Imaging of biomaterials in liquids: a comparison between conventional and Q-controlled amplitude modulation ('tapping mode') atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Ebeling, D.; Hölscher, H.; Fuchs, H.; Anczykowski, B.; Schwarz, U. D.

    2006-04-01

    Lambda phage DNA and DPPC thin films are imaged in liquids by atomic force microscopy applying the amplitude modulation mode ('tapping mode') with active enhancement of the Q-factor by a 'Q-control' electronics. The topography of the resulting images is compared with images obtained without active Q-control. To enable a meaningful comparison, individual scan lines are alternately recorded with and without Q-factor enhancement using scan parameters optimized for each mode separately. As the major finding, significant height differences of topographical features are observed between the two modes. The heights measured with active Q-control are reproducibly higher compared to the ones observed without Q enhancement. This effect is attributed to the reduction of tip-sample forces by Q-control.

  15. The structure of high-methoxyl sugar acid gels of citrus pectin as determined by AFM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Images of native high methoxyl sugar acid gels (HMSAG) were obtained by atomic force microscopy (AFM) in the Tapping ModeTM. Electronic thinning of the pectin strands to one pixel wide allowed the pectin network to be viewed in the absence of variable strand widths related to preferentially solvate...

  16. Qplus AFM driven nanostencil.

    PubMed

    Grévin, B; Fakir, M; Hayton, J; Brun, M; Demadrille, R; Faure-Vincent, J

    2011-06-01

    We describe the development of a novel setup, in which large stencils with suspended silicon nitride membranes are combined with atomic force microscopy (AFM) regulation by using tuning forks. This system offers the possibility to perform separate AFM and nanostencil operations, as well as combined modes when using stencil chips with integrated tips. The flexibility and performances are demonstrated through a series of examples, including wide AFM scans in closed loop mode, probe positioning repeatability of a few tens of nanometer, simultaneous evaporation of large (several hundred of micron square) and nanoscopic metals and fullerene patterns in static, multistep, and dynamic modes. This approach paves the way for further developments, as it fully combines the advantages of conventional stenciling with the ones of an AFM driven shadow mask. PMID:21721701

  17. Exploring the tip-sample interaction regimes in the presence of hysteretic forces in the tapping mode atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Korayem, M. H.; Eghbal, M. M.; Ebrahimi, N.

    2011-07-01

    In this article, the tip-sample interaction regimes in the presence of hysteretic forces are investigated using atomic force microscopy in the tapping mode. For this purpose, two samples that cause the formation of hysteretic forces, namely, silicon (stiff sample) with an adsorbed water film and polyethylene (compliant sample), are used. Also, for deriving the equation of motion of the microcantilever, the continuous beam model is used, and for determining the contact forces, depending on the sample under investigation, the Derjaguin-Muller-Toporov and Johnson-Kendall-Roberts contact mechanics models are used. The results indicate that the hysteretic interaction forces generate high-periodic and irregular responses at certain tip-sample separation distances. In fact, at these distances, a family of steady-state attractors is found that can be observed in one branch on the minimum tip-sample separation curves and in two separate branches on the average force curves. The reason for this occurrence might be the alternate formation of a liquid column between the probe tip and the sample (in the presence of ambient moisture), and for the compliant sample, the reason might be the alternate formation of an adhesion neck. In this article, the role of hysteretic forces in producing the hysteresis of the amplitude-separation curves is also explored.

  18. Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model

    PubMed Central

    2014-01-01

    Summary This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip–sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip–sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip–sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided. PMID:25383277

  19. An approach towards 3D sensitive AFM cantilevers

    NASA Astrophysics Data System (ADS)

    Koops, Richard; Fokkema, Vincent

    2014-04-01

    The atomic force microscope (AFM) tapping mode is a highly sensitive local probing technique that is very useful to study and measure surface properties down to the atomic scale. The tapping mode is mostly implemented using the resonance of the first bending mode of the cantilever and therefore provides sensitivity mainly along the direction of this oscillation. Driven by the semiconductor industry, there is an increasing need for accurate measurements of nanoscale structures for side wall characterization by AFM that requires additional sensitivity in the lateral direction. The conventional tapping mode has been augmented by various authors, for example by tilting the cantilever system (Cho et al 2011 Rev. Sci. Instrum. 82 023707) to access the sidewall or using a torsion mode (Dai et al 2011 Meas. Sci. Technol. 22 094009) of the cantilever to provide additional lateral sensitivity. These approaches however trade lateral sensitivity for vertical sensitivity or still lack sensitivity in the remaining lateral direction. We present an approach towards true 3D sensitivity for AFM cantilevers based on simultaneous excitation and optical detection of multiple cantilever resonance modes along three axes. Tuning the excitation of the cantilever to specific frequencies provides a mechanism to select only those cantilever modes that have the desired characteristics. Additionally, cantilever engineering has been used to design and create a substructure within the cantilever that has been optimized for specific resonance behavior around 4 MHz. In contrast to the conventional approach of using a piezo to actuate the cantilever modulation, we present results on photo-thermal excitation using an intensity modulated low-power laser source. By tightly focusing the excitation spot on the cantilever we were able to attain a deflection efficiency of 0.7 nm µW-1 for the first bending mode. The presented approach results in an efficient all optical excitation and deflection detection

  20. Measurement of Young's modulus variation with layer pair and interplanar spacing in gold–nickel nanolaminates using nanoindentation and the tapping mode

    SciTech Connect

    Ahmed, H. S. Tanvir; Jankowski, Alan F.

    2015-03-28

    The features of grain size and interface separation strengthen the mechanical behavior of metallic nanolaminates. In addition, the presence of interlayer lattice strains can lead to a superlattice structure within the nanolaminate. The superlattice affects intrinsic properties of technological interest including electronic, magnetic, and elastic. The complex elastic and plastic behaviors of gold–nickel nanolaminate superlattice coatings as studied using nanoindentation are revisited with the tapping mode of a force microscope. Young's modulus is determined with nanoindentation during the initial elastic unloading after plastic deformation at depths up to one-fifth the coating thickness. The tapping mode provides a measurement during the initial elastic deformation at depths of only a few nanometers. The tapping mode utilizes the shift in the resonant frequency of the probe-cantilever system as contact is made with the sample surface. Both of these nanoprobe test methods produce results for measurements conducted with loading normal to the surface plane. A softening in the Young's modulus of gold–nickel nanolaminate coatings occurs for samples with layer pair spacing between 1 and 9 nm. The magnitude of softening corresponds with a progressive increase in the tensile state as measured with the change of interplanar spacing along the growth direction.

  1. Measurement of Young's modulus variation with layer pair and interplanar spacing in gold-nickel nanolaminates using nanoindentation and the tapping mode

    NASA Astrophysics Data System (ADS)

    Ahmed, H. S. Tanvir; Jankowski, Alan F.

    2015-03-01

    The features of grain size and interface separation strengthen the mechanical behavior of metallic nanolaminates. In addition, the presence of interlayer lattice strains can lead to a superlattice structure within the nanolaminate. The superlattice affects intrinsic properties of technological interest including electronic, magnetic, and elastic. The complex elastic and plastic behaviors of gold-nickel nanolaminate superlattice coatings as studied using nanoindentation are revisited with the tapping mode of a force microscope. Young's modulus is determined with nanoindentation during the initial elastic unloading after plastic deformation at depths up to one-fifth the coating thickness. The tapping mode provides a measurement during the initial elastic deformation at depths of only a few nanometers. The tapping mode utilizes the shift in the resonant frequency of the probe-cantilever system as contact is made with the sample surface. Both of these nanoprobe test methods produce results for measurements conducted with loading normal to the surface plane. A softening in the Young's modulus of gold-nickel nanolaminate coatings occurs for samples with layer pair spacing between 1 and 9 nm. The magnitude of softening corresponds with a progressive increase in the tensile state as measured with the change of interplanar spacing along the growth direction.

  2. Characterization of the interaction between AFM tips and surface nanobubbles.

    PubMed

    Walczyk, Wiktoria; Schönherr, Holger

    2014-06-24

    While the presence of gaseous enclosures observed at various solid-water interfaces, the so-called "surface nanobubles", has been confirmed by many groups in recent years, their formation, properties, and stability have not been convincingly and exhaustively explained. Here we report on an atomic force microscopy (AFM) study of argon nanobubbles on highly oriented pyrolitic graphite (HOPG) in water to elucidate the properties of nanobubble surfaces and the mechanism of AFM tip-nanobubble interaction. In particular, the deformation of the nanobubble-water interface by the AFM tip and the question whether the AFM tip penetrates the nanobubble during scanning were addressed by this combined intermittent contact (tapping) mode and force volume AFM study. We found that the stiffness of nanobubbles was smaller than the cantilever spring constant and comparable with the surface tension of water. The interaction with the AFM tip resulted in severe quasi-linear deformation of the bubbles; however, in the case of tip-bubble attraction, the interface deformed toward the tip. We tested two models of tip-bubble interaction, namely, the capillary force and the dynamic interaction model, and found, depending on the tip properties, good agreement with experimental data. The results showed that the tip-bubble interaction strength and the magnitude of the bubble deformation depend strongly on tip and bubble geometry and on tip and substrate material, and are very sensitive to the presence of contaminations that alter the interfacial tension. In particular, nanobubbles interacted differently with hydrophilic and hydrophobic AFM tips, which resulted in qualitatively and quantitatively different force curves measured on the bubbles in the experiments. To minimize bubble deformation and obtain reliable AFM results, nanobubbles must be measured with a sharp hydrophilic tip and with a cantilever having a very low spring constant in a contamination-free system. PMID:24856074

  3. Tunable negative-tap photonic microwave filter based on a cladding-mode coupler and an optically injected laser of large detuning.

    PubMed

    Chan, Sze-Chun; Liu, Qing; Wang, Zhu; Chiang, Kin Seng

    2011-06-20

    A tunable negative-tap photonic microwave filter using a cladding-mode coupler together with optical injection locking of large wavelength detuning is demonstrated. Continuous and precise tunability of the filter is realized by physically sliding a pair of bare fibers inside the cladding-mode coupler. Signal inversion for the negative tap is achieved by optical injection locking of a single-mode semiconductor laser. To couple light into and out of the cladding-mode coupler, a pair of matching long-period fiber gratings is employed. The large bandwidth of the gratings requires injection locking of an exceptionally large wavelength detuning that has never been demonstrated before. Experimentally, injection locking with wavelength detuning as large as 27 nm was achieved, which corresponded to locking the 36-th side mode. Microwave filtering with a free-spectral range tunable from 88.6 MHz to 1.57 GHz and a notch depth larger than 35 dB was obtained. PMID:21716440

  4. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    DOE PAGESBeta

    Solares, Santiago D.

    2015-11-26

    This study introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretationmore » of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tappingmode imaging, for both of which the force curves exhibit the expected features. Lastly, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.« less

  5. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    SciTech Connect

    Solares, Santiago D.

    2015-11-26

    This study introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretation of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tappingmode imaging, for both of which the force curves exhibit the expected features. Lastly, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.

  6. Study of the sensitivity and resonant frequency of the torsional modes of an AFM cantilever with a sidewall probe based on a nonlocal elasticity theory.

    PubMed

    Abbasi, Mohammad; Karami Mohammadi, Ardeshir

    2015-05-01

    A relationship based on a nonlocal elasticity theory is developed to investigate the torsional sensitivity and resonant frequency of an atomic force microscope (AFM) with assembled cantilever probe (ACP). This ACP comprises a horizontal cantilever and a vertical extension, and a tip located at the free end of the extension, which makes the AFM capable of topography at sidewalls of microstructures. First, the governing differential equations of motion and boundary conditions for dynamic analysis are obtained by a combination of the basic equations of nonlocal elasticity theory and Hamilton's principle. Afterward, a closed-form expression for the sensitivity of vibration modes has been obtained using the relationship between the resonant frequency and contact stiffness of cantilever and sample. These analysis accounts for a better representation of the torsional behavior of an AFM with sidewall probe where the small-scale effect are significant. The results of the proposed model are compared with those of classical beam theory. The results show that the sensitivities and resonant frequencies of ACP predicted by the nonlocal elasticity theory are smaller than those obtained by the classical beam theory. PMID:25755027

  7. AFM study of polymer lubricants on hard disk surfaces

    NASA Astrophysics Data System (ADS)

    Bao, G. W.; Troemel, M.; Li, S. F. Y.

    Thin liquid films of PFPE (perfluoropolyether) lubricants dip-coated on hard disk surfaces were imaged with non-contact mode AFM. Demnum lubricants with phosphazene additives exhibited strong interactions with a silicon tip due to the formation of liquid bridges between the lubricants and the tip, as indicated by a remarkable hysteresis loop between approach and retraction curves in force vs. distance measurements. Features resulting from capillary forces due to tip tapping to the lubricants were revealed, which demonstrated that the capillary forces could be used to lock the non-contacting tip at a certain separation from the substrate surface to obtain AFM images. Force vs. distance curves for Fomblin Z-dol lubricants showed negligible hysteresis effects and features corresponding to lateral distortion of the tip by the lubricants only were observed. In both cases, only when the tip was positioned far above the surfaces could the natural distributions of the lubricants be imaged.

  8. PeakForce Tapping resolves individual microvilli on living cells.

    PubMed

    Schillers, Hermann; Medalsy, Izhar; Hu, Shuiqing; Slade, Andrea L; Shaw, James E

    2016-02-01

    Microvilli are a common structure found on epithelial cells that increase the apical surface thus enhancing the transmembrane transport capacity and also serve as one of the cell's mechanosensors. These structures are composed of microfilaments and cytoplasm, covered by plasma membrane. Epithelial cell function is usually coupled to the density of microvilli and its individual size illustrated by diseases, in which microvilli degradation causes malabsorption and diarrhea. Atomic force microscopy (AFM) has been widely used to study the topography and morphology of living cells. Visualizing soft and flexible structures such as microvilli on the apical surface of a live cell has been very challenging because the native microvilli structures are displaced and deformed by the interaction with the probe. PeakForce Tapping® is an AFM imaging mode, which allows reducing tip-sample interactions in time (microseconds) and controlling force in the low pico-Newton range. Data acquisition of this mode was optimized by using a newly developed PeakForce QNM-Live Cell probe, having a short cantilever with a 17-µm-long tip that minimizes hydrodynamic effects between the cantilever and the sample surface. In this paper, we have demonstrated for the first time the visualization of the microvilli on living kidney cells with AFM using PeakForce Tapping. The structures observed display a force dependence representing either the whole microvilli or just the tips of the microvilli layer. Together, PeakForce Tapping allows force control in the low pico-Newton range and enables the visualization of very soft and flexible structures on living cells under physiological conditions. PMID:26414320

  9. Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.

    PubMed

    Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

    2011-06-15

    In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are

  10. Device level 3D characterization using PeakForce AFM

    NASA Astrophysics Data System (ADS)

    Timoney, Padraig; Zhang, Xiaoxiao; Vaid, Alok; Hand, Sean; Osborne, Jason; Milligan, Eric; Feinstein, Adam

    2016-03-01

    Traditional metrology solutions face a range of challenges at the 1X node such as three dimensional (3D) measurement capabilities, shrinking overlay and critical dimension (CD) error budgets driven by multi-patterning and via in trench CD measurements. With advent of advanced technology nodes and 3D processing, an increasing need is emerging for in-die metrology including across-structure and structure-to-structure characterization. A myriad of work has emerged in the past few years intending to address these challenges from various aspects; in-die OCD with reduced spot size and tilt beam on traditional critical dimension scanning electron microscopy (CDSEM) for height measurements. This paper explores the latest capability offered by PeakForceTM Tapping Atomic Force Microscopy (PFT-AFM). The use of traditional harmonic tapping mode for scanning high aspect ratio, and complex "3D" wafer structures, results in limited depth probing capability as well as excessive tip wear. These limitations arise due to the large tip-sample interaction volume in such confined spaces. PeakForce Tapping eliminates these limitations through direct real time control of the tip-sample interaction contact force. The ability of PeakForce to measure, and respond directly to tip- sample interaction forces results in more detailed feature resolution, reduced tip wear, and improved depth capability. In this work, the PFT-AFM tool was applied for multiple applications, including the 14nm fin and replacement metal gate (RMG) applications outlined below. Results from DOE wafers, detailed measurement precision studies and correlation to reference metrology are presented for validation of this methodology. With the fin application, precision of 0.3nm is demonstrated by measuring 5 dies with 10 consecutive runs. Capability to resolve within-die and localized within-macro height variation is also demonstrated. Results obtained from the fin measurements support the increasing trend that measurements

  11. Characterization of deep nanoscale surface trenches with AFM using thin carbon nanotube probes in amplitude-modulation and frequency-force-modulation modes

    NASA Astrophysics Data System (ADS)

    Solares, Santiago D.

    2008-01-01

    The characterization of deep surface trenches with atomic force microscopy (AFM) presents significant challenges due to the sharp step edges that disturb the instrument and prevent it from faithfully reproducing the sample topography. Previous authors have developed AFM methodologies to successfully characterize semiconductor surface trenches with dimensions on the order of tens of nanometers. However, the study of imaging fidelity for features with dimensions smaller than 10 nm has not yet received sufficient attention. Such a study is necessary because small features in some cases lead to apparently high-quality images that are distorted due to tip and sample mechanical deformation. This paper presents multi-scale simulations, illustrating common artifacts affecting images of nanoscale trenches taken with fine carbon nanotube probes within amplitude-modulation and frequency-force-modulation AFM (AM-AFM and FFM-AFM, respectively). It also describes a methodology combining FFM-AFM with a step-in/step-out algorithm analogous to that developed by other groups for larger trenches, which can eliminate the observed artifacts. Finally, an overview of the AFM simulation methods is provided. These methods, based on atomistic and continuum simulation, have been previously used to study a variety of samples including silicon surfaces, carbon nanotubes and biomolecules.

  12. AFM as an analysis tool for high-capacity sulfur cathodes for Li-S batteries.

    PubMed

    Hiesgen, Renate; Sörgel, Seniz; Costa, Rémi; Carlé, Linus; Galm, Ines; Cañas, Natalia; Pascucci, Brigitta; Friedrich, K Andreas

    2013-01-01

    In this work, material-sensitive atomic force microscopy (AFM) techniques were used to analyse the cathodes of lithium-sulfur batteries. A comparison of their nanoscale electrical, electrochemical, and morphological properties was performed with samples prepared by either suspension-spraying or doctor-blade coating with different binders. Morphological studies of the cathodes before and after the electrochemical tests were performed by using AFM and scanning electron microscopy (SEM). The cathodes that contained polyvinylidene fluoride (PVDF) and were prepared by spray-coating exhibited a superior stability of the morphology and the electric network associated with the capacity and cycling stability of these batteries. A reduction of the conductive area determined by conductive AFM was found to correlate to the battery capacity loss for all cathodes. X-ray diffraction (XRD) measurements of Li2S exposed to ambient air showed that insulating Li2S hydrolyses to insulating LiOH. This validates the significance of electrical ex-situ AFM analysis after cycling. Conductive tapping mode AFM indicated the existence of large carbon-coated sulfur particles. Based on the analytical findings, the first results of an optimized cathode showed a much improved discharge capacity of 800 mA·g(sulfur)(-1) after 43 cycles. PMID:24205455

  13. AFM as an analysis tool for high-capacity sulfur cathodes for Li–S batteries

    PubMed Central

    Sörgel, Seniz; Costa, Rémi; Carlé, Linus; Galm, Ines; Cañas, Natalia; Pascucci, Brigitta; Friedrich, K Andreas

    2013-01-01

    Summary In this work, material-sensitive atomic force microscopy (AFM) techniques were used to analyse the cathodes of lithium–sulfur batteries. A comparison of their nanoscale electrical, electrochemical, and morphological properties was performed with samples prepared by either suspension-spraying or doctor-blade coating with different binders. Morphological studies of the cathodes before and after the electrochemical tests were performed by using AFM and scanning electron microscopy (SEM). The cathodes that contained polyvinylidene fluoride (PVDF) and were prepared by spray-coating exhibited a superior stability of the morphology and the electric network associated with the capacity and cycling stability of these batteries. A reduction of the conductive area determined by conductive AFM was found to correlate to the battery capacity loss for all cathodes. X-ray diffraction (XRD) measurements of Li2S exposed to ambient air showed that insulating Li2S hydrolyses to insulating LiOH. This validates the significance of electrical ex-situ AFM analysis after cycling. Conductive tapping mode AFM indicated the existence of large carbon-coated sulfur particles. Based on the analytical findings, the first results of an optimized cathode showed a much improved discharge capacity of 800 mA·g(sulfur)−1 after 43 cycles. PMID:24205455

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

    SciTech Connect

    Schiwek, Simon; Stark, Robert W. E-mail: dietz@csi.tu-darmstadt.de; Dietz, Christian E-mail: dietz@csi.tu-darmstadt.de; Heim, Lars-Oliver

    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.

  15. ezAFM: A low cost Atomic Force Microscope(AFM)

    NASA Astrophysics Data System (ADS)

    Celik, Umit; Celik, Kubra; Aslan, Husnu; Kehribar, Ihsan; Dede, Munir; Ozgur Ozer, H.; Oral, Ahmet

    2012-02-01

    A low cost AFM, ezAFM is developed for educational purposes as well as research. Optical beam deflection method is used to measure the deflection of cantilever. ezAFM scanner is built using voice coil motors (VCM) with ˜50x50x6 μm scan area. The microscope uses alignment free cantilevers, which minimizes setup times. FPGA based AFM feedback Control electronics is developed. FPGA technology allows us to drive all peripherals in parallel. ezAFM Controller is connected to PC by USB 2.0 interface as well as Wi-Fi. We have achieved <5nm lateral and ˜0.01nm vertical resolution. ezAFM can image single atomic steps in HOPG and mica. An optical microscope with <3 μm resolution is also integrated into the system. ezAFM supports different AFM operation modes such as dynamic mode, contact mode, lateral force microscopy. Advanced modes like magnetic force microscopy and electric force microscopy will be implemented later on. The new ezAFM system provides, short learning times for student labs, quick setup and easy to transport for portable applications with the best price/performance ratio. The cost of the system starts from 15,000, with system performance comparable with the traditional AFM systems.

  16. Analysis of AFM cantilever dynamics close to sample surface

    NASA Astrophysics Data System (ADS)

    Habibnejad Korayem, A.; Habibnejad Korayem, Moharam; Ghaderi, Reza

    2013-07-01

    For imaging and manipulation of biological specimens application of atomic force microscopy (AFM) in liquid is necessary. In this paper, tapping-mode AFM cantilever dynamics in liquid close to sample surface is modeled and simulated by well defining the contact forces. The effect of cantilever tilting angle has been accounted carefully. Contact forces have some differences in liquid in comparison to air or vacuum in magnitude or formulation. Hydrodynamic forces are also applied on the cantilever due to the motion in liquid. A continuous beam model is used with its first mode and forward-time simulation method for simulation of its hybrid dynamics and the frequency response and amplitude versus separation diagrams are extracted. The simulation results show a good agreement with experimental results. The resonance frequency in liquid is so small in comparison to air due to additional mass and also additional damping due to the viscosity of the liquid around. The results show that the effect of separation on free vibration amplitude is great. Its effect on resonance frequency is considerable too.

  17. Solid State Microstructure of Poly(L-lactide-co-meso-lactide) Copolymers by AFM

    NASA Astrophysics Data System (ADS)

    Kanchanasopa, M.; Manias, E.; Runt, J.

    2002-03-01

    The focus in the present study is on characterization of the lamellar morphology of poly(L-lactide) and two L-lactide/meso-lactide random copolymers containing 3 and 6 the same (Mn = 65,000, PDI = 2) and crystallization behavior is therefore controlled by comonomer content. Degrees of crystallinity and crystallization rates decrease substantially with increasing meso-lactide content in the copolymers. Tapping mode AFM experiments on the surfaces of films, previously isothermally crystallized at selected temperatures, were conducted. Similar experiments were also performed on cross-sections, microtomed from the crystallized films. Tapping force plays an important role in all experiments, particularly for low crystallinity samples. Mean lamellar thicknesses derived from analysis of height images agree well with those determined previously from small-angle x-ray scattering experiments.

  18. Carbon nanotube/carbon nanotube composite AFM probes prepared using ion flux molding

    NASA Astrophysics Data System (ADS)

    Chesmore, Grace; Roque, Carrollyn; Barber, Richard

    The performance of carbon nanotube-carbon nanotube composite (CNT/CNT composite) atomic force microscopy (AFM) probes is compared to that of conventional Si probes in AFM tapping mode. The ion flux molding (IFM) process, aiming an ion beam at the CNT probe, aligns the tip to a desired angle. The result is a relatively rigid tip that is oriented to offset the cantilever angle. Scans using these probes reveal an improvement in image accuracy over conventional tips, while allowing higher aspect ratio imaging of 3D surface features. Furthermore, the lifetimes of CNT-CNT composite tips are observed to be longer than both conventional tips and those claimed for other CNT technologies. Novel applications include the imaging of embiid silk. Supported by the Clare Boothe Luce Research Scholars Award and Carbon Design Innovations.

  19. Browsing TAP Services with TapHandle

    NASA Astrophysics Data System (ADS)

    Louys, M.; Michel, L.; Mantelet, G.; Bonnarel, F.

    2012-09-01

    TapHandle is a Web application merging multiple services based on the IVOA Table Access Protocol (TAP) in one page. TAP resources are presented in an expandable tree whose leaves represent SQL tables. Both table description and content can be immediately displayed. A smart ADQL editor helps to setup queries on one table. A shopping cart facility allows users to get data of interest. A filter enriches the data layout with anchors pointing to remote services.

  20. Controlled AFM detachments and movement of nanoparticles: gold clusters on HOPG at different temperatures

    NASA Astrophysics Data System (ADS)

    Tripathi, Manoj; Paolicelli, Guido; D'Addato, Sergio; Valeri, Sergio

    2012-06-01

    The effect of temperature on the onset of movement of gold nanoclusters (diameter 27 nm) deposited on highly oriented pyrolytic graphite (HOPG) has been studied by atomic force microscopy (AFM) techniques. Using the AFM with amplitude modulation (tapping mode AFM) we have stimulated and controlled the movement of individual clusters. We show how, at room temperature, controlled detachments and smooth movements can be obtained for clusters having dimensions comparable to or smaller than the tip radius. Displacement is practically visible in real time and it can be started and stopped easily by adjusting only one parameter, the tip amplitude oscillation. Analysing the energy dissipation signal at the onset of nanocluster sliding we evaluated a detachment threshold energy as a function of temperature in the range 300-413 K. We also analysed single cluster thermal induced displacement and combining this delicate procedure with AFM forced movement behaviour we conclude that detachment threshold energy is directly related to the activation energy of nanocluster diffusion and it scales linearly with temperature as expected for a single-particle thermally activated process.

  1. Simultaneous Nanomechanical and Electrochemical Mapping: Combining Peak Force Tapping Atomic Force Microscopy with Scanning Electrochemical Microscopy.

    PubMed

    Knittel, Peter; Mizaikoff, Boris; Kranz, Christine

    2016-06-21

    Soft electronic devices play a crucial role in, e.g., neural implants as stimulating electrodes, transducers for biosensors, or selective drug-delivery. Because of their elasticity, they can easily adapt to their environment and prevent immunoreactions leading to an overall improved long-term performance. In addition, flexible electronic devices such as stretchable displays will be increasingly used in everyday life, e.g., for so-called electronic wearables. Atomic force microscopy (AFM) is a versatile tool to characterize these micro- and nanostructured devices in terms of their topography. Using advanced imaging techniques such as peak force tapping (PFT), nanomechanical properties including adhesion, deformation, and Young's modulus can be simultaneously mapped along with surface features. However, conventional AFM provides limited laterally resolved information on electrical or electrochemical properties such as the activity of an electrode array. In this study, we present the first combination of AFM with scanning electrochemical microscopy (SECM) in PFT mode, thereby offering spatially correlated electrochemical and nanomechanical information paired with high-resolution topographical data under force control (QNM-AFM-SECM). The versatility of this combined scanning probe approach is demonstrated by mapping topographical, electrochemical, and nanomechanical properties of gold microelectrodes and of gold electrodes patterned onto polydimethylsiloxane. PMID:27203837

  2. NASA/UK TAP

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The purpose of the Technology Applications Program (TAP) is to provide problem solving information and assistance to both the public and private sectors in the Commonwealth of Kentucky, with emphasis primarily in the public sector. The TAP accesses over 1200 online computer databases, including files from the U.S., Canada, Europe, and Australia. During the 1985 to 1986 contract period, TAP responded to 645 inquiries which resulted in an increase of 16 percent over the 1984 to 1985 contract period. The activities of TAP for the 1985 to 1986 contract period are summarized.

  3. TAp73 promotes anabolism

    PubMed Central

    Amelio, Ivano; Antonov, Alexey A.; Catani, Maria Valeria; Massoud, Renato; Bernassola, Francesca; Knight, Richard A.; Melino, Gerry; Rufini, Alessandro

    2014-01-01

    Metabolic adaptation has emerged as a hallmark of cancer and a promising therapeutic target, as rapidly proliferating cancer cells adapt their metabolism increasing nutrient uptake and reorganizing metabolic fluxes to support biosynthesis. The transcription factor p73 belongs to the p53-family and regulates tumorigenesis via its two N-terminal isoforms, with (TAp73) or without (ΔNp73) a transactivation domain. TAp73 acts as tumor suppressor, at least partially through induction of cell cycle arrest and apoptosis and through regulation of genomic stability. Here, we sought to investigate whether TAp73 also affects metabolic profiling of cancer cells. Using high throughput metabolomics, we unveil a thorough and unexpected role for TAp73 in promoting Warburg effect and cellular metabolism. TAp73-expressing cells show increased rate of glycolysis, higher amino acid uptake and increased levels and biosynthesis of acetyl-CoA. Moreover, we report an extensive TAp73-mediated upregulation of several anabolic pathways including polyamine and synthesis of membrane phospholipids. TAp73 expression also increases cellular methyl-donor S-adenosylmethionine (SAM), possibly influencing methylation and epigenetics, and promotes arginine metabolism, suggestive of a role in extracellular matrix (ECM) modeling. In summary, our data indicate that TAp73 regulates multiple metabolic pathways that impinge on numerous cellular functions, but that, overall, converge to sustain cell growth and proliferation. PMID:25514460

  4. Exploring the retention properties of CaF2 nanoparticles as possible additives for dental care application with tapping-mode atomic force microscope in liquid.

    PubMed

    Wasem, Matthias; Köser, Joachim; Hess, Sylvia; Gnecco, Enrico; Meyer, Ernst

    2014-01-13

    Amplitude-modulation atomic force microscopy (AM-AFM) is used to determine the retention properties of CaF2 nanoparticles adsorbed on mica and on tooth enamel in liquid. From the phase-lag of the forced cantilever oscillation the local energy dissipation at the detachment point of the nanoparticle was determined. This enabled us to compare different as-synthesized CaF2 nanoparticles that vary in shape, size and surface structure. CaF2 nanoparticles are candidates for additives in dental care products as they could serve as fluorine-releasing containers preventing caries during a cariogenic acid attack on the teeth. We show that the adherence of the nanoparticles is increased on the enamel substrate compared to mica, independently of the substrate roughness, morphology and size of the particles. PMID:24455460

  5. Exploring the retention properties of CaF2 nanoparticles as possible additives for dental care application with tapping-mode atomic force microscope in liquid

    PubMed Central

    Köser, Joachim; Hess, Sylvia; Gnecco, Enrico; Meyer, Ernst

    2014-01-01

    Summary Amplitude-modulation atomic force microscopy (AM-AFM) is used to determine the retention properties of CaF2 nanoparticles adsorbed on mica and on tooth enamel in liquid. From the phase-lag of the forced cantilever oscillation the local energy dissipation at the detachment point of the nanoparticle was determined. This enabled us to compare different as-synthesized CaF2 nanoparticles that vary in shape, size and surface structure. CaF2 nanoparticles are candidates for additives in dental care products as they could serve as fluorine-releasing containers preventing caries during a cariogenic acid attack on the teeth. We show that the adherence of the nanoparticles is increased on the enamel substrate compared to mica, independently of the substrate roughness, morphology and size of the particles. PMID:24455460

  6. Examination of Humidity Effects on Measured Thickness and Interfacial Phenomena of Exfoliated Graphene on SiO2 via AC-AFM

    NASA Astrophysics Data System (ADS)

    Jinkins, Katherine; Camacho, Jorge; Farina, Lee; Wu, Yan

    2015-03-01

    Tapping (AC) mode Atomic Force Microscopy (AFM) is commonly used to determine the thickness of graphene samples. However, AFM measurements have been shown to be sensitive to environmental conditions such as adsorbed water, in turn dependent on relative humidity (RH). In the present study, AC-AFM is used to measure the thickness and loss tangent of exfoliated graphene on silicon dioxide (SiO2) as RH is increased from 10% to 80%. We show that the measured thickness of graphene is dependent on RH. Loss tangent is an AFM imaging technique that interprets the phase information as a relationship between the stored and dissipated energy in the tip-sample interaction. This study demonstrates the loss tangent of the graphene and oxide regions are both affected by humidity, with generally higher loss tangent for graphene than SiO2. As RH increases, we observe the loss tangent of both materials approaches the same value. We hypothesize that there is a layer of water trapped between the graphene and SiO2 substrate to explain this observation. Using this interpretation, the loss tangent images also indicate movement and change in this trapped water layer as RH increases, which impacts the measured thickness of graphene using AC-AFM.

  7. Phase-Imaging with a Sharpened Multi-Walled Carbon Nanotube AFM Tip: Investigation of Low-k Dielectric Polymer Hybrids

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V.; Stevens, Ramsey M.; Meyyappan, M.; Volksen, Willi; Miller, Robert D.

    2005-01-01

    Phase shift tapping mode scanning force microscopy (TMSFM) has evolved into a very powerful technique for the nanoscale surface characterization of compositional variations in heterogeneous samples. Phase shift signal measures the difference between the phase angle of the excitation signal and the phase angle of the cantilever response. The signal correlates to the tip-sample inelastic interactions, identifying the different chemical and/or physical property of surfaces. In general, the resolution and quality of scanning probe microscopic images are highly dependent on the size of the scanning probe tip. In improving AFM tip technology, we recently developed a technique for sharpening the tip of a multi-walled carbon nanotube (CNT) AFM tip, reducing the radius of curvature of the CNT tip to less than 5 nm while still maintaining the inherent stability of multi-walled CNT tips. Herein we report the use of sharpened (CNT) AFM tips for phase-imaging of polymer hybrids, a precursor for generating nanoporous low-k dielectrics for on-chip interconnect applications. Using sharpened CNT tips, we obtained phase-contrast images having domains less than 10 nm. In contrast, conventional Si tips and unsharpened CNT tips (radius greater than 15 nm) were not able to resolve the nanoscale domains in the polymer hybrid films. C1early, the size of the CNT tip contributes significantly to the resolution of phase-contrast imaging. In addition, a study on the nonlinear tapping dynamics of the multi-walled CNT tip indicates that the multi-walled CNT tip is immune to conventional imaging instabilities related to the coexistence of attractive and repulsive tapping regimes. This factor may also contribute to the phase-contrast image quality of multi-walled CNT AFM tips. This presentation will also offer data in support of the stability of the CNT tip for phase shift TMSFM.

  8. In-situ Measurement of In-Plane and Out-of-Plane Force Gradient with a Torsional Resonance Mode AFM

    NASA Astrophysics Data System (ADS)

    Su, C.; Huang, L.; Neilson, P.; Kelley, V.

    2003-12-01

    We introduce a new method to perform sequential measurements of the in-plane and out-of-plane magnetic force gradient components using the same topographic scan lines to preserve geometrical position registry at the nanometer scale. This method applies both flexural and torsional resonant oscillations of the same atomic force microscope cantilever probe for the determination of respective vertical and lateral force gradient components in a sequence of scans. Using magnetic domains in a hard drive with known stray field, as simulated by finite element analysis, we have demonstrated that the two oscillation modes provide complementary information about the orientation of the magnetic momentum of the probe tips. The matching of both vertical and lateral force gradient data with that of the finite element simulation occurs only at a unique orientation of tip magnetization. Furthermore, it was found that force gradient measurements using torsion mode are able to determine in-plane anisotropy.

  9. Physics on Tap

    ERIC Educational Resources Information Center

    Wheeler, Andrew P. S.

    2012-01-01

    This article aims to describe how to visualize surface tension effects in liquid jets. A simple experiment is proposed using the liquid jet flow from a mains water tap/faucet. Using a modern digital camera with a high shutter speed, it is possible to visualize the instabilities (capillary waves) that form within the jet due to the action of…

  10. Combined quantitative ultrasonic and time-resolved interaction force AFM imaging

    SciTech Connect

    Parlak, Z.; Degertekin, F. L.

    2011-01-15

    The authors describe a method where quantitative ultrasonic atomic force microscopy (UAFM) is achieved during time-resolved interaction force (TRIF) imaging in intermittent contact mode. The method uses a calibration procedure for quantitative UAFM. It improves elasticity measurements of stiff regions of surfaces while retaining the capabilities of the TRIF mode for topography, adhesion, dissipation, and elasticity measurements on soft regions of sample surfaces. This combination is especially advantageous when measuring and imaging samples with broad stiffness range in a nondestructive manner. The experiments utilize an active AFM probe with high bandwidth and the UAFM calibration is performed by measuring the magnitude of the time-resolved UAFM signal at a judiciously chosen frequency for different contact stiffness values during individual taps. Improved sensitivity to stiff surface elasticity is demonstrated on a special sample. The results show that combining UAFM with TRIF provides 2.5 GPa (5%) standard deviation on the silicon surface reduced Young's modulus, representing 5x improvement over using only TRIF mode imaging.

  11. Target Acquisition and Positioning Study (TAPS)

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The Scientific Instruments for the Large Space Telescope (LST) require a high degree of accuracy for positioning targets within their respective entrance apertures. The acquisition, verification of position, and guidance during an experiment must be accomplished with a minimum loss of observing time for the maximum effectiveness of the total mission. This study evaluates several viable concepts and modes of operation that are applicable for a Target Acquisition and Positioning System (TAPS) that is responsive to the LST instrument requirements.

  12. TAP usage in SIMBAD

    NASA Astrophysics Data System (ADS)

    Anaïs, O.; Gregory, M.; Marc, W.

    2015-09-01

    TAP (Table Access Protocol promoted by IVOA) is available on SIMBAD web site since July 2012. We will have a look of all kinds of uses and try to figure out how people use it in SIMBAD. Thanks to ADQL (Astronomical Data Query Language), everyone can write their own query using criteria on all data available in the database. In the SIMBAD database, more than 30 tables are available. It can be rather difficult to write a complex query. We will see how many joins between tables are used, and how many fields are used in the queries. The SIMBAD usage is going to change thanks to this new feature, a new way to search in the database.

  13. Spectral and AFM characterization of trimethylammoniophenylporphyrin and concanavalin A associate in solution and monolithic SiO 2 gels obtained by the sol-gel method

    NASA Astrophysics Data System (ADS)

    Polska, Katarzyna; Radzki, Stanisław

    2008-06-01

    The associate between water-soluble cationic tetrakis[4-(trimethylammonio)phenyl] porphyrin (H2TTMePP) and concanavalin A (Con A) has been studied in the tris-buffer solution by absorption and emission electron spectroscopy. The porphyrin and porphyrin concanavalin associate has been incorporated into the monolithic pure silica gels obtained by polycondensation of tetraethoxysilane. The optically transparent dried gels were studied using absorption and fluorescence spectroscopic techniques and also by the tapping mode of atomic force microscopy (AFM). Complex formation between porphyrin and concanavalin takes place in both solution and gel. In these media porphyrin and its lectin associate exhibit luminescence emission in the vis-ir range when excited with visible light. Upon binding to concanavalin A the increase in porphyrin fluorescence intensity and the red-shift in the absorption and emission maxima have been observed. AFM visualisation of porphyrin and the porphyrin-concanavalin conjugate shows significant differences between nanostructures of the pure porphyrin and complex doped gels. It has been found that the ''smooth'' surfaces of silica gels prepared by the sol-gel technique are an excellent medium for the AFM visualisation of biomolecules.

  14. TAP 1: Training Program Manual

    SciTech Connect

    Not Available

    1993-08-01

    The Training Accreditation Program (TAP) was established by the Department of Energy (DOE) to assist in achieving excellence in the development and implementation of performance-based nuclear facility training programs. The TAP establishes the objectives and criteria against which DOE nuclear facility training is evaluated for accreditation. The TAP Staff provides assistance to contractors, develops training guidelines, and evaluates the quality and effectiveness of facility training. This manual describes the accreditation process, provides functional descriptions for positions which require accredited training programs, provides a brief discussion of performance-based training, contains the objectives and criteria that must be addressed in training programs subject to accreditation, and includes a glossary.

  15. Modeling the Interaction between AFM Tips and Pinned Surface Nanobubbles.

    PubMed

    Guo, Zhenjiang; Liu, Yawei; Xiao, Qianxiang; Schönherr, Holger; Zhang, Xianren

    2016-01-26

    Although the morphology of surface nanobubbles has been studied widely with different AFM modes, AFM images may not reflect the real shapes of the nanobubbles due to AFM tip-nanobubble interactions. In addition, the interplay between surface nanobubble deformation and induced capillary force has not been well understood in this context. In our work we used constraint lattice density functional theory to investigate the interaction between AFM tips and pinned surface nanobubbles systematically, especially concentrating on the effects of tip hydrophilicity and shape. For a hydrophilic tip contacting a nanobubble, its hydrophilic nature facilitates its departure from the bubble surface, displaying a weak and intermediate-range attraction. However, when the tip squeezes the nanobubble during the approach process, the nanobubble shows an elastic effect that prevents the tip from penetrating the bubble, leading to a strong nanobubble deformation and repulsive interactions. On the contrary, a hydrophobic tip can easily pierce the vapor-liquid interface of the nanobubble during the approach process, leading to the disappearance of the repulsive force. In the retraction process, however, the adhesion between the tip and the nanobubble leads to a much stronger lengthening effect on nanobubble deformation and a strong long-range attractive force. The trends of force evolution from our simulations agree qualitatively well with recent experimental AFM observations. This favorable agreement demonstrates that our model catches the main intergradient of tip-nanobubble interactions for pinned surface nanobubbles and may therefore provide important insight into how to design minimally invasive AFM experiments. PMID:26751634

  16. Physics of Beer Tapping

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rodríguez, Javier; Casado-Chacón, Almudena; Fuster, Daniel

    2014-11-01

    The popular bar prank known in colloquial English as beer tapping consists in hitting the top of a beer bottle with a solid object, usually another bottle, to trigger the foaming over of the former within a few seconds. Despite the trick being known for a long time, to the best of our knowledge, the phenomenon still lacks scientific explanation. Although it seems natural to think that shock-induced cavitation enhances the diffusion of CO2 from the supersaturated bulk liquid into the bubbles by breaking them up, the subtle mechanism by which this happens remains unknown. Here, we show that the overall foaming-over process can be divided into three stages where different physical phenomena take place in different time scales: namely, the bubble-collapse (or cavitation) stage, the diffusion-driven stage, and the buoyancy-driven stage. In the bubble-collapse stage, the impact generates a train of expansion-compression waves in the liquid that leads to the fragmentation of preexisting gas cavities. Upon bubble fragmentation, the sudden increase of the interface-area-to-volume ratio enhances mass transfer significantly, which makes the bubble volume grow by a large factor until CO2 is locally depleted. At that point buoyancy takes over, making the bubble clouds rise and eventually form buoyant vortex rings whose volume grows fast due to the feedback between the buoyancy-induced rising speed and the advection-enhanced CO2 transport from the bulk liquid to the bubble. The physics behind this explosive process sheds insight into the dynamics of geological phenomena such as limnic eruptions.

  17. PREFACE: Non-contact AFM Non-contact AFM

    NASA Astrophysics Data System (ADS)

    Giessibl, Franz J.; Morita, Seizo

    2012-02-01

    This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of

  18. A Unique Self-Sensing, Self-Actuating AFM Probe at Higher Eigenmodes

    PubMed Central

    Wu, Zhichao; Guo, Tong; Tao, Ran; Liu, Leihua; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2015-01-01

    With its unique structure, the Akiyama probe is a type of tuning fork atomic force microscope probe. The long, soft cantilever makes it possible to measure soft samples in tapping mode. In this article, some characteristics of the probe at its second eigenmode are revealed by use of finite element analysis (FEA) and experiments in a standard atmosphere. Although the signal-to-noise ratio in this environment is not good enough, the 2 nm resolution and 0.09 Hz/nm sensitivity prove that the Akiyama probe can be used at its second eigenmode under FM non-contact mode or low amplitude FM tapping mode, which means that it is easy to change the measuring method from normal tapping to small amplitude tapping or non-contact mode with the same probe and equipment. PMID:26580619

  19. Effect of tip mass on frequency response and sensitivity of AFM cantilever in liquid.

    PubMed

    Farokh Payam, Amir; Fathipour, Morteza

    2015-03-01

    The effect of tip mass on the frequency response and sensitivity of atomic force microscope (AFM) cantilever in the liquid environment is investigated. For this purpose, using Euler-Bernoulli beam theory and considering tip mass and hydrodynamic functions in a liquid environment, an expression for the resonance frequencies of AFM cantilever in liquid is derived. Then, based on this expression, the effect of the surface contact stiffness on the flexural mode of a rectangular AFM cantilever in fluid is investigated and compared with the case where the AFM cantilever operates in the air. The results show that in contrast with an air environment, the tip mass has no significant impact on the resonance frequency and sensitivity of the AFM cantilever in the liquid. Hence, analysis of AFM behaviour in liquid environment by neglecting the tip mass is logical. PMID:25562584

  20. Radioactive substances in tap water.

    PubMed

    Atsuumi, Ryo; Endo, Yoshihiko; Suzuki, Akihiko; Kannotou, Yasumitu; Nakada, Masahiro; Yabuuchi, Reiko

    2014-01-01

    A 9.0 magnitude (M) earthquake with an epicenter off the Sanriku coast occurred at 14: 46 on March 11, 2011. TEPCO Fukushima Daiichi Nuclear Power Plant (F-1 NPP) was struck by the earthquake and its resulting tsunami. Consequently a critical nuclear disaster developed, as a large quantity of radioactive materials was released due to a hydrogen blast. On March 16(th), 2011, radioiodine and radioactive cesium were detected at levels of 177 Bq/kg and 58 Bq/kg, respectively, in tap water in Fukushima city (about 62km northwest of TEPCO F-1 NPP). On March 20th, radioiodine was detected in tap water at a level of 965 Bq/kg, which is over the value-index of restrictions on food and drink intake (radioiodine 300 Bq/kg (infant intake 100 Bq/kg)) designated by the Nuclear Safety Commission. Therefore, intake restriction measures were taken regarding drinking water. After that, although the all intake restrictions were lifted, in order to confirm the safety of tap water, an inspection system was established to monitor all tap water in the prefecture. This system has confirmed that there has been no detection of radioiodine or radioactive cesium in tap water in the prefecture since May 5(th), 2011. Furthermore, radioactive strontium ((89) Sr, (90)Sr) and plutonium ((238)Pu, (239)Pu+(240)Pu) in tap water and the raw water supply were measured. As a result, (89) Sr, (238)Pu, (239)Pu+(240)Pu were undetectable and although (90)Sr was detected, its committed effective dose of 0.00017 mSv was much lower than the yearly 0.1 mSv of the World Health Organization guidelines for drinking water quality. In addition, the results did not show any deviations from past inspection results. PMID:25030724

  1. Geothermal Energy: Tapping the Potential

    ERIC Educational Resources Information Center

    Johnson, Bill

    2008-01-01

    Ground source geothermal energy enables one to tap into the earth's stored renewable energy for heating and cooling facilities. Proper application of ground-source geothermal technology can have a dramatic impact on the efficiency and financial performance of building energy utilization (30%+). At the same time, using this alternative energy…

  2. Dynamics of a Tapped Granular Column

    NASA Astrophysics Data System (ADS)

    Rosato, Anthony; Blackmore, Denis; Zuo, Luo; Hao, Wu; Horntrop, David

    2015-11-01

    We consider the behavior of a column of spheres subjected to a time-dependent vertical taps. Of interest are various dynamical properties, such as the motion of its mass center, its response to taps of different intensities and forms, and the effect of system size and material properties. The interplay between diverse time and length scales are the key contributors to the column's evolving dynamics. Soft sphere discrete element simulations were conducted over a very wide parameter space to obtain a portrait of column behavior as embodied by the collective dynamics of the mass center motion. Results compared favorably with a derived reduced-order paradigm of the mass center motion (surprisingly analogous to that for a single bouncing ball on an oscillating plate) with respect to dynamical regimes and their transitions. A continuum model obtained from a system of Newtonian equations, as a locally averaged limit in the transport mode along trajectories is described, and a numerical solution protocol for a one-dimensional system is outlined. Typical trajectories and density evolution profiles are shown. We conclude with a discussion of our investigations to relate predictions of the continuum and reduced dynamical systems models with discrete simulations.

  3. In situ QCM and TM-AFM investigations of the early stages of degradation of silver and copper surfaces

    NASA Astrophysics Data System (ADS)

    Kleber, Ch.; Hilfrich, U.; Schreiner, M.

    2007-01-01

    The early stages of atmospheric corrosion of pure copper and pure silver specimens were investigated performing in situ tapping mode atomic force microscopy (TM-AFM), in situ quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS). The information obtained by TM-AFM is the change of the topography of the sample surfaces with emphasis on the shape and lateral distribution of the corrosion products grown within the first hours of weathering. The simultaneously performed in situ QCM measurements are indicating the mass changes due to possibly occurring corrosive processes on the surface during weathering and are therefore a valuable tool for the determination of corrosion rates. Investigations were carried out in synthetic air at different levels of relative humidity (RH) with and without addition of 250 ppb SO 2 as acidifying agent. On a polished copper surface the growth of corrosion products could be observed by TM-AFM analysis at 60% RH without any addition of acidifying gases [M. Wadsak, M. Schreiner, T. Aastrup, C. Leygraf, Surf. Sci. 454-456 (2000) 246-250]. On a weathered copper surface the addition of SO 2 to the moist air stream leads to the formation of additional features as already described in the literature [M. Wadsak, M. Schreiner, T. Aastrup, C. Leygraf, Surf. Sci. 454-456 (2000) 246-250; Ch. Kleber, J. Weissenrieder, M. Schreiner, C. Leygraf, Appl. Surf. Sci. 193 (2002) 245-253]. Exposing a silver specimen to humidity leads to the degradation of the surface structure as well as to a formation of corrosion products, which could be detected by in situ QCM measurements. After addition of 250 ppb SO 2 to the moist gas stream an increase of the formed feature's volume on the silver surface could be observed by TM-AFM measurements. The results obtained additionally from the in situ QCM measurements confirm the influence of SO 2 due to a further increase of the mass of the formed corrosion layer (and therefore an increase of the

  4. High speed AFM studies of 193 nm immersion photoresists during TMAH development

    NASA Astrophysics Data System (ADS)

    Ngunjiri, Johnpeter; Meyers, Greg; Cameron, Jim; Suzuki, Yasuhiro; Jeon, Hyun; Lee, Dave; Choi, Kwang Mo; Kim, Jung Woo; Im, Kwang-Hwyi; Lim, Hae-Jin

    2016-03-01

    In this paper we report on our studies of the dynamic process of resist development in real time. Using High Speed - Atomic Force Microscopy (HS-AFM) in dilute developer solution, changes in morphology and nanomechanical properties of patterned resist were monitored. The Bruker Dimension FastScan AFMTM was applied to analyze 193 nm acrylic-based immersion resists in developer. HS-AFM operated in Peak Force mapping mode allowed for concurrent measurements of image topography resist stiffness, adhesion to AFM probe and deformation during development. In our studies we focused on HS-AFM topography data as it readily revealed detailed information about initial resist morphology, followed by a resist swelling process and eventual dissolution of the exposed resist areas. HS-AFM showed potential for tracking and understanding development of patterned resist films and can be useful in evaluating the dissolution properties of different resist designs.

  5. Conductive supports for combined AFM SECM on biological membranes

    NASA Astrophysics Data System (ADS)

    Frederix, Patrick L. T. M.; Bosshart, Patrick D.; Akiyama, Terunobu; Chami, Mohamed; Gullo, Maurizio R.; Blackstock, Jason J.; Dooleweerdt, Karin; de Rooij, Nico F.; Staufer, Urs; Engel, Andreas

    2008-09-01

    Four different conductive supports are analysed regarding their suitability for combined atomic force and scanning electrochemical microscopy (AFM-SECM) on biological membranes. Highly oriented pyrolytic graphite (HOPG), MoS2, template stripped gold, and template stripped platinum are compared as supports for high resolution imaging of reconstituted membrane proteins or native membranes, and as electrodes for transferring electrons from or to a redox molecule. We demonstrate that high resolution topographs of the bacterial outer membrane protein F can be recorded by contact mode AFM on all four supports. Electrochemical feedback experiments with conductive cantilevers that feature nanometre-scale electrodes showed fast re-oxidation of the redox couple Ru(NH3)63+/2+ with the two metal supports after prolonged immersion in electrolyte. In contrast, the re-oxidation rates decayed quickly to unpractical levels with HOPG or MoS2 under physiological conditions. On HOPG we observed heterogeneity in the re-oxidation rate of the redox molecules with higher feedback currents at step edges. The latter results demonstrate the capability of conductive cantilevers with small electrodes to measure minor variations in an SECM signal and to relate them to nanometre-scale features in a simultaneously recorded AFM topography. Rapid decay of re-oxidation rate and surface heterogeneity make HOPG or MoS2 less attractive for combined AFM-SECM experiments on biological membranes than template stripped gold or platinum supports.

  6. Transient response of tapping scanning force microscopy in liquids

    SciTech Connect

    Chen, G.Y.; Warmack, R.J. |; Oden, P.I.; Thundat, T.

    1996-03-01

    Tapping-mode scanning force microscopy in liquids is usually accomplished by acoustic excitation of the cantilever because of the strong viscous damping. Contact of the tip with the sample surface results in a damping of the cantilever amplitude with an anharmonic response. This interaction is modeled as a viscous-damped, one-dimensional harmonic oscillator periodically perturbed by an exponential surface potential. Experimental results verify the validity of the model. {copyright} {ital 1996 American Vacuum Society}

  7. MOS-based nanocapacitor using C-AFM

    NASA Astrophysics Data System (ADS)

    Hill, Daniel; Sadewasser, Sascha; Aymerich, Xavier

    2003-04-01

    This report details the attempts made to realise nanocapacitors for nanoscale MOS based integrated circuits by AFM anodic oxidation, and therefore isolation, of nano-sized squares of poly-silicon, titanium and aluminium on Si/SiO2. Conductive AFM (C-AFM) was used to perform topographical and electrical characterisation. The experiments were performed with contact mode C-AFM, in ambient air, using Pt-Ir, Co-Cr and Ti coated (20nm) n-type silicon cantilevers. Each sample consisted of a 3-5nm thick conductor deposited on 6nm of SiO2, which was thermally grown on Phosphorus doped (1019 cm-3) n-type Si(100) substrates. Standard cleaning and passivation processes were used. Poly-silicon was immediately found to be too rough to oxidise. Initial current-voltage measurements inside of the titanium-oxide squares suggest initial isolation followed by degradation through Fowler-Nordheim tunnelling. Measurement inconsistencies seen suggest charge storage on the surface or tip with the barrier height of the native titanium oxide thought to be responsible. Al has a thicker natural oxide. To overcome this we designed a series of structures consisting of a Ti finger on SiO2, that is connected to a Ti bond pad, allowing direct probing by a semiconductor parameter analyser. AFM anodic oxidation was performed upon these Ti fingers to reduce their in-plane dimensions towards the nanoscale. To confirm the existence of a nanocapacitor topographical and electrical measurements were then done on and around them.

  8. Weyl semimetal state in TaP: experimental discovery

    NASA Astrophysics Data System (ADS)

    Shibayev, Pavel; Hasan Research Group Team

    Despite their extreme rareness in nature, Weyl semimetals provide the first realization of Weyl fermions. After families of tantalum-based (TaAs, TaP) and niobium-based (NbAs, NbP) compounds were recently predicted as Weyl semimetal candidates, our group experimentally realized the Weyl semimetal state in TaP. Angle-resolved photoemission spectroscopy (ARPES) was used to probe the surface features of TaP. Weyl fermion cones and nodes were directly observed in the bulk, and Fermi arcs were observed on the surface. The surface states were found to possess a rich structure, containing topological Fermi arcs and topologically trivial closed contours in the neighborhood of Weyl points. This finding opens up possibilities to study the relationship between trivial and topological surface states on the surface of a Weyl semimetal. By determining the number of chiral edge modes on a closed path enclosing the Weyl node, bulk-boundary correspondence was demonstrated, leading to the establishment of a topologically nontrivial nature of the Weyl semimetal state in TaP. The work at Princeton and Princeton-led ARPES measurements were supported by the Gordon and Betty Moore Foundations EPiQS Initiative through Grant GBMF4547 (Hasan) and by U.S. Department of Energy DE-FG-02-05ER46200.

  9. Non-plugging pressure tap

    DOEpatents

    Echtler, Joseph P.

    1978-01-01

    A pressure tap having utility in an environment of a solid-gas phase process flow includes a tubular coupling part having attached over a passage therethrough at an end opening thereof exposed to the flow a grating of spaced bars, and affixed internally across a passage therethrough so as to cover over an opening therein a screen which maintains contained within the passage between it and the grating a matrix of smooth spheres. The grating bars are so oriented by the disposition of the aforesaid end opening with respect to the flow such that accumulations of solids therebetween tending to bridge the opening are removed therefrom by the flow.

  10. Single ricin detection by AFM chemomechanical mapping

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research reports a method of detecting ricin molecules immobilized on chemically modified gold (Au;111) surface by chemomechanically mapping the molecular interactions with a chemically modified Atomic Force Microscope (AFM) tip. AFM images resolved the different fold-up conformations of single...

  11. Manufacturing process of nanofluidics using afm probe

    NASA Astrophysics Data System (ADS)

    Karingula, Varun Kumar

    A new process for fabricating a nano fluidic device that can be used in medical application is developed and demonstrated. Nano channels are fabricated using a nano tip in indentation mode on AFM (Atomic Force Microscopy). The nano channels are integrated between the micro channels and act as a filter to separate biomolecules. Nano channels of 4 to7 m in length, 80nm in width, and at varying depths from 100nm to 850 nm allow the resulting device to separate selected groups of lysosomes and other viruses. Sharply developed vertical micro channels are produced from a deep reaction ion etching followed by deposition of different materials, such as gold and polymers, on the top surface, allowing the study of alternative ways of manufacturing a nanofluidic device. PDMS (Polydimethylsiloxane) bonding is performed to close the top surface of the device. An experimental setup is used to test and validate the device by pouring fluid through the channels. A detailed cost evaluation is conducted to compare the economical merits of the proposed process. It is shown that there is a 47:7% manufacturing time savings and a 60:6% manufacturing cost savings.

  12. Imaging surface nanobubbles at graphite-water interfaces with different atomic force microscopy modes

    NASA Astrophysics Data System (ADS)

    Yang, Chih-Wen; Lu, Yi-Hsien; Hwang, Ing-Shouh

    2013-05-01

    We have imaged nanobubbles on highly ordered pyrolytic graphite (HOPG) surfaces in pure water with different atomic force microscopy (AFM) modes, including the frequency-modulation, the tapping, and the PeakForce techniques. We have compared the performance of these modes in obtaining the surface profiles of nanobubbles. The frequency-modulation mode yields a larger height value than the other two modes and can provide more accurate measurement of the surface profiles of nanobubbles. Imaging with PeakForce mode shows that a nanobubble appears smaller and shorter with increasing peak force and disappears above a certain peak force, but the size returns to the original value when the peak force is reduced. This indicates that imaging with high peak forces does not cause gas removal from the nanobubbles. Based on the presented findings and previous AFM observations, the existing models for nanobubbles are reviewed and discussed. The model of gas aggregate inside nanobubbles provides a better explanation for the puzzles of the high stability and the contact angle of surface nanobubbles.

  13. Imaging of a soft, weakly adsorbing, living cell with a colloid probe tapping atomic force microscope technique.

    PubMed

    McNamee, Cathy E; Pyo, Nayoung; Tanaka, Saaya; Kanda, Yoichi; Higashitani, Ko

    2006-01-15

    Here, we propose a new method to improve the atomic force microscopy (AFM) image resolution of soft samples, such as cells, in liquid. Attaching a colloid probe to a cantilever was seen improve the image resolution of a living cell in a physiological buffer solution, obtained by the normal tapping mode, when compared to an image obtained using a regular cantilever tip. This may be due to the averaging out of the cantilever tip swinging caused by the visco-elasticity of the cell. The resolution was best, when silica spheres with a 3.3 microm diameter were attached. Although larger spheres gave a resolution better than a bare cantilever tip, their resolution was less than that obtained for the 3.3 microm diameter silica colloid. This dependency of the image resolution on the colloid probe size may be a result of the increased macroscopic van der Waals attraction between the cell and probe, the decreased repulsive force dependence on the cantilever probe radius, and the decrease in resolution due to the increased probe size. The size of the colloid probe, which should be attached to the cantilever to give the best image resolution, would be the one that optimises the combined result of these facts. PMID:16406494

  14. Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves.

    PubMed

    Al-Musawi, R S J; Brousseau, E B; Geng, Y; Borodich, F M

    2016-09-23

    Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves. PMID:27532247

  15. Probing ternary solvent effect in high Voc polymer solar cells using advanced AFM techniques

    DOE PAGESBeta

    Li, Chao; Soleman, Mikhael; Lorenzo, Josie; Dhasmana, Nitesh; Chantharasupawong, Panit; Ievlev, Anton; Gesquiere, Andre; Tetard, Laurene; Thomas, Jayan

    2016-01-25

    This work describes a simple method to develop a high Voc low band gap PSCs. In addition, two new atomic force microscopy (AFM)-based nanoscale characterization techniques to study the surface morphology and physical properties of the structured active layer are introduced. With the help of ternary solvent processing of the active layer and C60 buffer layer, a bulk heterojunction PSC with Voc more than 0.9 V and conversion efficiency 7.5% is developed. In order to understand the fundamental properties of the materials ruling the performance of the PSCs tested, AFM-based nanoscale characterization techniques including Pulsed-Force-Mode AFM (PFM-AFM) and Mode-Synthesizing AFMmore » (MSAFM) are introduced. Interestingly, MSAFM exhibits high sensitivity for direct visualization of the donor–acceptor phases in the active layer of the PSCs. Lastly, conductive-AFM (cAFM) studies reveal local variations in conductivity in the donor and acceptor phases as well as a significant increase in photocurrent in the PTB7:ICBA sample obtained with the ternary solvent processing.« less

  16. Nanoscale rippling on polymer surfaces induced by AFM manipulation

    PubMed Central

    2015-01-01

    Summary Nanoscale rippling induced by an atomic force microscope (AFM) tip can be observed after performing one or many scans over the same area on a range of materials, namely ionic salts, metals, and semiconductors. However, it is for the case of polymer films that this phenomenon has been widely explored and studied. Due to the possibility of varying and controlling various parameters, this phenomenon has recently gained a great interest for some technological applications. The advent of AFM cantilevers with integrated heaters has promoted further advances in the field. An alternative method to heating up the tip is based on solvent-assisted viscoplastic deformations, where the ripples develop upon the application of a relatively low force to a solvent-rich film. An ensemble of AFM-based procedures can thus produce nanoripples on polymeric surfaces quickly, efficiently, and with an unprecedented order and control. However, even if nanorippling has been observed in various distinct modes and many theoretical models have been since proposed, a full understanding of this phenomenon is still far from being achieved. This review aims at summarizing the current state of the art in the perspective of achieving control over the rippling process on polymers at a nanoscale level. PMID:26733086

  17. Investigation of the Mechanoelectrical Transduction at Single Stereocilia by Afm

    NASA Astrophysics Data System (ADS)

    Langer, M. G.; Fink, S.; Löffler, K.; Koitschev, A.; Zenner, H.-P.

    2003-02-01

    The transduction of sound into an electrical signal in the inner ear is closely related to the mechanical properties of the hair bundles cytoskeleton and cross-linkage. In this study the effect of lateral cross-links on hair bundle mechanics and the transduction current response is demonstrated on the level of individual stereocilia. For experiments stereocilia of outer hair cells of postnatal rats (P3 - P8) were scanned with a sharp AFM tip at nanometerscale. Transduction currents were simultaneously recorded in the whole-cell-recording mode with patch clamp. AFM was used as a nanotool for local mechanical stimulation and force measurement at stereocilia whereas patch clamp serves as a detector for the electrical response of the cell. In a first experiment force transmission between adjacent stereocilia of the V- and W- shaped hair bundles of outer hair cells was investigated. Results showed that a force exerted to a single stereocilium declined to 36 % at the nearest adjacent stereocilium of the same row. This result supposes AFM to be convenient for local displacement of single stereocilia. For control, the local response of transduction channels was measured at single stereocilia of the same hair bundle. Measured transduction current amplitudes ranged from 9 to 49 pA supposing an opening of one to five transduction channels. Both, weak force transmission by lateral cross-links and small transduction current amplitudes indicate a weak mechanical interaction between individual stereocilia of the tallest row of stereocilia of outer hair cells from postnatal rats.

  18. TAP 3: Training Program Support Manual

    SciTech Connect

    Not Available

    1993-08-01

    The Training Accreditation Program (TAP) establishes objectives and criteria against which DOE nuclear facility training is evaluated to determine readiness for accreditation. TAP 3 has been developed to assist the contractor in preparing the initial Self-Evaluation Report, Training Program Accreditation Plan, and the CSER (contractor self-evaluation report).

  19. 49 CFR 192.151 - Tapping.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the pipeline. (b) Where a ductile iron pipe is tapped, the extent of full-thread engagement and the... determined by service conditions. (c) Where a threaded tap is made in cast iron or ductile iron pipe, the... (102 millimeters) cast iron or ductile iron pipe, without reinforcement. However, in areas...

  20. 49 CFR 192.151 - Tapping.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... the pipeline. (b) Where a ductile iron pipe is tapped, the extent of full-thread engagement and the... determined by service conditions. (c) Where a threaded tap is made in cast iron or ductile iron pipe, the... (102 millimeters) cast iron or ductile iron pipe, without reinforcement. However, in areas...

  1. 49 CFR 192.151 - Tapping.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the pipeline. (b) Where a ductile iron pipe is tapped, the extent of full-thread engagement and the... determined by service conditions. (c) Where a threaded tap is made in cast iron or ductile iron pipe, the... (102 millimeters) cast iron or ductile iron pipe, without reinforcement. However, in areas...

  2. Self-Advancing Step-Tap Drills

    NASA Technical Reports Server (NTRS)

    Pettit, Donald R.; Camarda, Charles J.; Penner, Ronald K.; Franklin, Larry D.

    2007-01-01

    Self-advancing tool bits that are hybrids of drills and stepped taps make it possible to form threaded holes wider than about 1/2 in. (about 13 mm) without applying any more axial force than is necessary for forming narrower pilot holes. These self-advancing stepped-tap drills were invented for use by space-suited astronauts performing repairs on reinforced carbon/carbon space-shuttle leading edges during space walks, in which the ability to apply axial drilling forces is severely limited. Self-advancing stepped-tap drills could also be used on Earth for making wide holes without applying large axial forces. A self-advancing stepped-tap drill (see figure) includes several sections having progressively larger diameters, typically in increments between 0.030 and 0.060 in. (between about 0.8 and about 1.5 mm). The tip section, which is the narrowest, is a pilot drill bit that typically has a diameter between 1/8 and 3/16 in. (between about 3.2 and about 4.8 mm). The length of the pilot-drill section is chosen, according to the thickness of the object to be drilled and tapped, so that the pilot hole is completed before engagement of the first tap section. Provided that the cutting-edge geometry of the drill bit is optimized for the material to be drilled, only a relatively small axial force [typically of the order of a few pounds (of the order of 10 newtons)] must be applied during drilling of the pilot hole. Once the first tap section engages the pilot hole, it is no longer necessary for the drill operator to apply axial force: the thread engagement between the tap and the workpiece provides the axial force to advance the tool bit. Like the pilot-drill section, each tap section must be long enough to complete its hole before engagement of the next, slightly wider tap section. The precise values of the increments in diameter, the thread pitch, the rake angle of the tap cutting edge, and other geometric parameters of the tap sections must be chosen, in consideration of

  3. Comparison of dynamic lever STM and noncontact AFM

    NASA Astrophysics Data System (ADS)

    Guggisberg, M.; Bammerlin, M.; Lüthi, R.; Loppacher, C.; Battiston, F.; Lü, J.; Baratoff, A.; Meyer, E.; Güntherodt, H.-J.

    We investigate interaction effects which occur in scanning tunneling microscopy (STM) by performing local force spectroscopy with an oscillating tip while imaging Si(111)7×7 terraces in the dynamic lever STM mode (constant time-averaged current). It is found that true atomic resolution is achieved close to the minimum of the resonance frequency vs. distance curve and even closer to the sample. On the other hand true atomic resolution in noncontact AFM (constant frequency shift) is expected several nm away from this minimum, in the range where the frequency shift becomes more negative with decreasing distance.

  4. Nano Mechanical Machining Using AFM Probe

    NASA Astrophysics Data System (ADS)

    Mostofa, Md. Golam

    Complex miniaturized components with high form accuracy will play key roles in the future development of many products, as they provide portability, disposability, lower material consumption in production, low power consumption during operation, lower sample requirements for testing, and higher heat transfer due to their very high surface-to-volume ratio. Given the high market demand for such micro and nano featured components, different manufacturing methods have been developed for their fabrication. Some of the common technologies in micro/nano fabrication are photolithography, electron beam lithography, X-ray lithography and other semiconductor processing techniques. Although these methods are capable of fabricating micro/nano structures with a resolution of less than a few nanometers, some of the shortcomings associated with these methods, such as high production costs for customized products, limited material choices, necessitate the development of other fabricating techniques. Micro/nano mechanical machining, such an atomic force microscope (AFM) probe based nano fabrication, has, therefore, been used to overcome some the major restrictions of the traditional processes. This technique removes material from the workpiece by engaging micro/nano size cutting tool (i.e. AFM probe) and is applicable on a wider range of materials compared to the photolithographic process. In spite of the unique benefits of nano mechanical machining, there are also some challenges with this technique, since the scale is reduced, such as size effects, burr formations, chip adhesions, fragility of tools and tool wear. Moreover, AFM based machining does not have any rotational movement, which makes fabrication of 3D features more difficult. Thus, vibration-assisted machining is introduced into AFM probe based nano mechanical machining to overcome the limitations associated with the conventional AFM probe based scratching method. Vibration-assisted machining reduced the cutting forces

  5. Excimer laser machining of optical fiber taps

    NASA Astrophysics Data System (ADS)

    Coyle, Richard J.; Serafino, Anthony J.; Grimes, Gary J.; Bortolini, James R.

    1991-05-01

    Precision openings for construction of an optical backplane have been machined in an optical fiber using an excimer laser operating at a wavelength of 193 nm. The openings were made by imaging the laser beam onto the polymer fiber cladding with a telescope, then ablating the cladding with a sufficient number of pulses to expose the core. Circular openings measuring 250 and 625 microns and elliptical openings measuring 650 X 350 microns have been made in the cladding of a 1 mm polymer-clad silica fiber. Examination by scanning electron microscopy reveals that the best quality openings are obtained with either the smaller circular geometry or the elliptical geometry. For various reasons, elliptical openings, with the major axis oriented along the longitudinal axis of the fiber, appear more suitable for tap construction. Individual optical fiber taps have been constructed by attaching a tap fiber to a laser machined opening in a central fiber using an ultraviolet-curable acralate. Individual tap measurements were made on the elliptical and the 250 micron circular openings. In addition, a triple tap assembly was made using elliptical tap openings. These results indicate that the excimer laser machining technique may be applicable to the construction of a linear tapped bus for optical backplanes.

  6. Traffic Aware Planner (TAP) Flight Evaluation

    NASA Technical Reports Server (NTRS)

    Maris, John M.; Haynes, Mark A.; Wing, David J.; Burke, Kelly A.; Henderson, Jeff; Woods, Sharon E.

    2014-01-01

    NASA's Traffic Aware Planner (TAP) is a cockpit decision support tool that has the potential to achieve significant fuel and time savings when it is embedded in the data-rich Next Generation Air Transportation System (NextGen) airspace. To address a key step towards the operational deployment of TAP and the NASA concept of Traffic Aware Strategic Aircrew Requests (TASAR), a system evaluation was conducted in a representative flight environment in November, 2013. Numerous challenges were overcome to achieve this goal, including the porting of the foundational Autonomous Operations Planner (AOP) software from its original simulation-based, avionics-embedded environment to an Electronic Flight Bag (EFB) platform. A flight-test aircraft was modified to host the EFB, the TAP application, an Automatic Dependent Surveillance Broadcast (ADS-B) processor, and a satellite broadband datalink. Nine Evaluation Pilots conducted 26 hours of TAP assessments using four route profiles in the complex eastern and north-eastern United States airspace. Extensive avionics and video data were collected, supplemented by comprehensive inflight and post-flight questionnaires. TAP was verified to function properly in the live avionics and ADS-B environment, characterized by recorded data dropouts, latency, and ADS-B message fluctuations. Twelve TAP-generated optimization requests were submitted to ATC, of which nine were approved, and all of which resulted in fuel and/or time savings. Analysis of subjective workload data indicated that pilot interaction with TAP during flight operations did not induce additional cognitive loading. Additionally, analyses of post-flight questionnaire data showed that the pilots perceived TAP to be useful, understandable, intuitive, and easy to use. All program objectives were met, and the next phase of TAP development and evaluations with partner airlines is in planning for 2015.

  7. Energy-Saving RAM-Power Tap

    NASA Technical Reports Server (NTRS)

    Bruner, Alan Roy

    1987-01-01

    Reverse-flow HEXFET(R) minimizes voltage drop and power dissipation. HEXFET(R) scheme reduces voltage drop by approximately 80 percent. Design for power tap for random-access memory (RAM) has potential application in digital systems.

  8. Hydration states of AFm cement phases

    SciTech Connect

    Baquerizo, Luis G.; Matschei, Thomas; Scrivener, Karen L.; Saeidpour, Mahsa; Wadsö, Lars

    2015-07-15

    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  9. AFM indentation study of breast cancer cells

    SciTech Connect

    Li, Q.S.; Lee, G.Y.H.; Ong, C.N.; Lim, C.T.

    2008-10-03

    Mechanical properties of individual living cells are known to be closely related to the health and function of the human body. Here, atomic force microscopy (AFM) indentation using a micro-sized spherical probe was carried out to characterize the elasticity of benign (MCF-10A) and cancerous (MCF-7) human breast epithelial cells. AFM imaging and confocal fluorescence imaging were also used to investigate their corresponding sub-membrane cytoskeletal structures. Malignant (MCF-7) breast cells were found to have an apparent Young's modulus significantly lower (1.4-1.8 times) than that of their non-malignant (MCF-10A) counterparts at physiological temperature (37 deg. C), and their apparent Young's modulus increase with loading rate. Both confocal and AFM images showed a significant difference in the organization of their sub-membrane actin structures which directly contribute to their difference in cell elasticity. This change may have facilitated easy migration and invasion of malignant cells during metastasis.

  10. Association of TAP1 and TAP2 genes with susceptibility to pulmonary tuberculosis in Koreans.

    PubMed

    Roh, Eun Youn; Yoon, Jong Hyun; Shin, Sue; Song, Eun Young; Park, Myoung Hee

    2015-06-01

    Tuberculosis remains an important public health problem in Koreans. However, very few studies have reported on the genetic factors associated with TB susceptibility in Koreans. The aim of this study was to elucidate the genetic factors associated with susceptibility to pulmonary tuberculosis (PTB). We investigated the transporter associated with antigen processing -1 (TAP1) and TAP2 gene polymorphisms in 160 Korean PTB patients (categorized according to extent of lesion and TB medication history) and 210 controls. TAP2*C/E frequency was significantly increased in the PTB (pc = 0.004, OR = 2.28). TAP2*Bky2/C/E were enriched in the retreated, far-advanced and total PTB compared with the controls (pc = 0.015, OR = 3.27; pc = 0.019, OR = 2.56; pc = 2.8 × 10(-4) , OR = 2.42, respectively). In the comparison of TAP2 gene with the DRB1*08:03, which is associated with TAP2*Bky2 and PTB in Koreans, we demonstrated the hierarchy of these association factors. TAP2*C/E is independent factors as strong as DRB1*08:03, and TAP2*C/E interacts with DRB1*08:03, resulting in a striking combined association. Our results suggest that TAP2 gene has an association with PTB susceptibility, the extent of the lesion or recurrence. These associations are independent from and additive with DRB1*08:03. PMID:25846714

  11. Nanoscale crystallization of phase change Ge2Sb2Te5 film with AFM lithography.

    PubMed

    Kim, JunHo

    2010-01-01

    We have made nanoindents on Ge(2)Sb(2)Te(5)(GST) films using electric field-assisted atomic force microscope (AFM) lithography. GST shows increase of material density and electric conductivity as it changes from amorphous to crystalline phases. By applying electric field between AFM probe-tip and GST surface, nanoscale crystallization could be induced on tip contact area. As the crystallized GST exhibits increase of material density, that is to say depression of volume, nanoindented surface with crystallization is created on host amorphous GST (a-GST) film. For the AFM lithography, a highly conductive tip, which showed voltage-switching characteristics in current-voltage spectroscopy of GST film, was found to be very suitable for recording and sensing crystallized nanoindents on the GST film. By varying sample bias voltages, we performed nanoscale crystallization, and measured the nanostructured film in AFM conductance-image (C-image) mode and topography-image (T-image) mode, simultaneously. Two types of crystallized wires were fabricated on (a-GST) film. Type-I was sensed in only C-image, whereas Type-II was sensed in both C-image and T-image. These nanowires are discussed in terms of crystallization of GST and sensitivity of current (or topography) sensing. By repeated lithography, larger size of nanoindented wires were also produced, which indicates line-dimension controllability of AFM lithography. PMID:20853405

  12. Conductance of AFM Deformed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Svizhenko, Alexei; Maiti, Amitesh; Anatram, M. P.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on the electrical conductivity of carbon nanotubes upon deformation by atomic force microscopy (AFM). The density of states and conductance were computed using four orbital tight-binding method with various parameterizations. Different chiralities develop bandgap that varies with chirality.

  13. Contact nanomechanical measurements with the AFM

    NASA Astrophysics Data System (ADS)

    Geisse, Nicholas

    2013-03-01

    The atomic force microscope (AFM) has found broad use in the biological sciences largely due to its ability to make measurements on unfixed and unstained samples under liquid. In addition to imaging at multiple spatial scales ranging from micro- to nanometer, AFMs are commonly used as nanomechanical probes. This is pertinent for cell biology, as it has been demonstrated that the geometrical and mechanical properties of the extracellular microenvironment are important in such processes as cancer, cardiovascular disease, muscular dystrophy, and even the control of cell life and death. Indeed, the ability to control and quantify these external geometrical and mechanical parameters arises as a key issue in the field. Because AFM can quantitatively measure the mechanical properties of various biological samples, novel insights to cell function and to cell-substrate interactions are now possible. As the application of AFM to these types of problems is widened, it is important to understand the performance envelope of the technique and its associated data analyses. This talk will discuss the important issues that must be considered when mechanical models are applied to real-world data. Examples of the effect of different model assumptions on our understanding of the measured material properties will be shown. Furthermore, specific examples of the importance of mechanical stimuli and the micromechanical environment to the structure and function of biological materials will be presented.

  14. A Batch Fabricated SECM-AFM Probe

    NASA Astrophysics Data System (ADS)

    Dobson, P. S.; Macpherson, J. V.; Holder, M.; Weaver, J. M. R.

    2003-12-01

    A scheme for the fabrication of combined Scanning Electrochemical Microscopy — Atomic Force Microscopy (SECM-AFM) probes is presented for both silicon nitride and silicon cantilevers. The advantages over exsisting methods used for their production is explained. The process flow is described and initial results from electrodeposition of silver are presented.

  15. Probing the probe: AFM tip-profiling via nanotemplates to determine Hamaker constants from phase-distance curves.

    PubMed

    Rodriguez, Raul D; Lacaze, Emmanuelle; Jupille, Jacques

    2012-10-01

    A method to determine the van der Waals forces from phase-distance curves recorded by atomic force microscopy (AFM) in tapping mode is presented. The relationship between the phase shift and the tip-sample distance is expressed as a function of the product of the Hamaker constant by tip radius. Silica-covered silicon tips are used to probe silica-covered silicon substrate in dry conditions to avoid capillary effects. Tips being assumed spherical, radii are determined in situ by averaging profiles recorded in different directions on hematite nanocrystals acting as nanotemplates, thus accounting for tip anisotropy. Through a series of reproducible measurements performed with tips of various radii (including the in-situ characterization of a damaged tip), a value of (6.3±0.4)×10(-20) J is found for the Hamaker constant of interacting silica surfaces in air, in good agreement with tabulated data. The results demonstrate that the onset of the tip-surface interaction is dominated by the van der Waals forces and that the total force can be modeled in the framework of the harmonic approximation. Based on the tip radius and the Hamaker constant associated to the tip-substrate system, the model is quite flexible. Once the Hamaker constant is known, a direct estimate of the tip size can be achieved whereas when the tip size is known, a quantitative evaluation of the van der Waals force becomes possible on different substrates with a spatial resolution at the nanoscale. PMID:22922181

  16. Fabrication of tungsten probe for hard tapping operation in atomic force microscopy.

    PubMed

    Han, Guebum; Ahn, Hyo-Sok

    2016-02-01

    We propose a method of producing a tungsten probe with high stiffness for atomic force microscopy (AFM) in order to acquire enhanced phase contrast images and efficiently perform lithography. A tungsten probe with a tip radius between 20nm and 50nm was fabricated using electrochemical etching optimized by applying pulse waves at different voltages. The spring constant of the tungsten probe was determined by finite element analysis (FEA), and its applicability as an AFM probe was evaluated by obtaining topography and phase contrast images of a Si wafer sample partly coated with Au. Enhanced hard tapping performance of the tungsten probe compared with a commercial Si probe was confirmed by conducting hard tapping tests at five different oscillation amplitudes on single layer graphene grown by chemical vapor deposition (CVD). To analyze the damaged graphene sample, the test areas were investigated using tip-enhanced Raman spectroscopy (TERS). The test results demonstrate that the tungsten probe with high stiffness was capable of inducing sufficient elastic and plastic deformation to enable obtaining enhanced phase contrast images and performing lithography, respectively. PMID:26630069

  17. Torsional tapping atomic force microscopy for molecular resolution imaging of soft matter

    NASA Astrophysics Data System (ADS)

    Hobbs, Jamie; Mullin, Nic

    2012-02-01

    Despite considerable advances in image resolution on challenging, soft systems, a method for obtaining molecular resolution on `real' samples with significant surface roughness has remained elusive. Here we will show that a relatively new technique, torsional tapping AFM (TTAFM), is capable of imaging with resolution down to 3.7 Angrstrom on the surface of `bulk' polymer films [1]. In TTAFM T-shaped cantilevers are driven into torsional oscillation. As the tip is offset from the rotation axis this provides a tapping motion. Due to the high frequency and Q of the oscillation and relatively small increase in spring constant, improved cantilever dynamics and force sensitivity are obtained. As the tip offset from the torsional axis is relatively small (typically 25 microns), the optical lever sensitivity is considerably improved compared to flexural oscillation. Combined these give a reduction in noise floor by a factor of 12 just by changing the cantilever geometry. The ensuing low noise allows the use of ultra-sharp `whisker' tips with minimal blunting. As the cantilevers remain soft in the flexural axis, the force when imaging with error is also reduced, further protecting the tip. We will show that this combination allows routine imaging of the molecular structure of semicrystalline polymer films, including chain folds, loose loops and tie-chains in polyethylene, and the helical conformation of polypropylene within the crystal, using a standard, commercial AFM. [4pt] [1] N Mullin, JK Hobbs, PRL 107, 197801 (2011)

  18. Gaining Momentum, Losing Ground. Tapping America's Potential (TAP) Progress Report, 2008. Executive Summary

    ERIC Educational Resources Information Center

    Tapping America's Potential, 2008

    2008-01-01

    In July 2005, Business Roundtable and fifteen of America's most prominent business organizations--Tapping America's Potential, the TAP coalition--issued a report stating that "one of the pillars of American economic prosperity--U.S. scientific and technological superiority--is beginning to atrophy even as other nations are developing their own…

  19. A mechanical evaluation of pre-tapped and self-tapped screws in small bones.

    PubMed

    Bell, J C; Ness, M G

    2007-01-01

    The purpose of this study was to compare the holding powers of 2.7 mm pre-tapped and self-tapped screws placed closely together and tightened in small bones. Pairs of metatarsals were collected from healthy, skeletally mature Greyhounds and part of a 2.7 mm dynamic compression plate was fixed to the dorsal surface of each bone using three 2.7 mm screws. Identical screws were used throughout but only one of each pair of bones had threads pre-cut using a tap prior to insertion. All of the screws were tightened before the constructs were mounted in a materials testing machine and the centrally placed screw was loaded incrementally until failure. Load-deformation curves were plotted and yield point, ultimate load to failure, stiffness and energy prior to yield point were measured. Mean values were recorded for each parameter and Student's T-test was used to test the null hypothesis that there is no difference in holding power between pre-tapped and self-tapped screws. Significant mechanical differences were not found between pre-tapped and self-tapped screws placed closely together and tightened into small bones. Self-tapped screws can be considered for use in small animal surgery even when multiple screws are to be placed closely together in relatively small pieces of bone. PMID:18038003

  20. Self-advancing step-tap tool

    NASA Technical Reports Server (NTRS)

    Pettit, Donald R. (Inventor); Penner, Ronald K. (Inventor); Franklin, Larry D. (Inventor); Camarda, Charles J. (Inventor)

    2008-01-01

    Methods and tool for simultaneously forming a bore in a work piece and forming a series of threads in said bore. In an embodiment, the tool has a predetermined axial length, a proximal end, and a distal end, said tool comprising: a shank located at said proximal end; a pilot drill portion located at said distal end; and a mill portion intermediately disposed between said shank and said pilot drill portion. The mill portion is comprised of at least two drill-tap sections of predetermined axial lengths and at least one transition section of predetermined axial length, wherein each of said at least one transition section is sandwiched between a distinct set of two of said at least two drill-tap sections. The at least two drill-tap sections are formed of one or more drill-tap cutting teeth spirally increasing along said at least two drill-tap sections, wherein said tool is self-advanced in said work piece along said formed threads, and wherein said tool simultaneously forms said bore and said series of threads along a substantially similar longitudinal axis.

  1. TAp73 transcriptionally represses BNIP3 expression

    PubMed Central

    Petrova, Varvara; Mancini, Mara; Agostini, Massimiliano; Knight, Richard A; Annicchiarico-Petruzzelli, Margherita; Barlev, Nikolai A; Melino, Gerry; Amelio, Ivano

    2015-01-01

    TAp73 is a tumor suppressor transcriptional factor, belonging to p53 family. Alteration of TAp73 in tumors might lead to reduced DNA damage response, cell cycle arrest and apoptosis. Carcinogen-induced TAp73−/− tumors display also increased angiogenesis, associated to hyperactivition of hypoxia inducible factor signaling. Here, we show that TAp73 suppresses BNIP3 expression, directly binding its gene promoter. BNIP3 is a hypoxia responsive protein, involved in a variety of cellular processes, such as autophagy, mitophagy, apoptosis and necrotic-like cell death. Therefore, through different cellular process altered expression of BNIP3 may differently contribute to cancer development and progression. We found a significant upregulation of BNIP3 in human lung cancer datasets, and we identified a direct association between BNIP3 expression and survival rate of lung cancer patients. Our data therefore provide a novel transcriptional target of TAp73, associated to its antagonistic role on HIF signaling in cancer, which might play a role in tumor suppression. PMID:25950386

  2. Physical properties of polyacrylamide gels probed by AFM and rheology

    NASA Astrophysics Data System (ADS)

    Abidine, Yara; Laurent, Valérie M.; Michel, Richard; Duperray, Alain; Iulian Palade, Liviu; Verdier, Claude

    2015-02-01

    Polymer gels have been shown to behave as viscoelastic materials but only a small amount of data is usually provided in the glass transition. In this paper, the dynamic moduli G\\prime and G\\prime\\prime of polyacrylamide hydrogels are investigated using both an AFM in contact force modulation mode and a classical rheometer. The validity is shown by the matching of the two techniques. Measurements are carried out on gels of increasing polymer concentration in a wide frequency range. A model based on fractional derivatives is successfully used, covering the whole frequency range. G\\text{N}0 , the plateau modulus, as well as several other parameters are obtained at low frequencies. The model also predicts the slope a of both moduli in the glass transition, and a transition frequency f\\text{T} is introduced to separate the gel-like behavior with the glassy state. Its variation with polymer content c gives a dependence f\\text{T}∼ c1.6 , in good agreement with previous theories. Therefore, the AFM data provides new information on the physics of polymer gels.

  3. Dual AFM probes alignment based on vision guidance

    NASA Astrophysics Data System (ADS)

    Zhang, Hua-kun; Gao, Si-tian; Lu, Ming-zhen; Wang, Long-long

    2013-10-01

    Atomic force microscope (AFM) with dual probes that operate together can measure both side walls excellently at the same time, which virtually eliminates the prevalent effect of probe width that contributes a large component of uncertainty in measurement results and finally obtains the critical dimension (CD)(e.g. the linewidth) through data synthesis. In calibration process, the dual probes must contact each other in advance, which realizes the alignment in the three dimensions, to establish a zero reference point and ensure the accuracy of measurement. Because nowadays the optical resolution of advanced lens have exceeded micrometer range, and the size of probes is within micro level, it is possible to acquire dual probes images in both horizontal and vertical directions, through which the movement of the probes can be controlled in time. In order to further enhance the alignment precision, sub-pixel edge detection method based on Zernike orthogonal moment is used to obtain relative position between these two probes, which helps the tips alignment attains sub-micron range. Piezoelectric nanopositioning stages calibrated by laser interferometer are used to implement fine movement of the probes to verify the accuracy of the experimental results. To simplify the system, novel self-sensing and self-actuating probe based on a quartz tuning fork combined with a micromachined cantilever is used for dynamic mode AFM. In this case, an external optical detection system is not needed, so the system is simple and small.

  4. Ensuring cost effectiveness in the TAP process

    SciTech Connect

    Trego, A.L.

    1992-06-16

    The Training Accredition Program (TAP) at the Waste Isolation Division (WID) is discussed by the general manager. Cost effectiveness in the TAP process is made possible by saving through sharing which refers to the exchange and co-development of information and technology among Westinghouse Government owned-contractor operators and with other organizations. In 1990 a comprehensive management and supervisor training (MAST) program plan was devised and a MAST certification program of 31 self-paced written moduler was developed. This program has proven to be inexpensive to develop and implement when compared to classroom training. In addition, total quality is used as a tool to continuously improve work process. Continuous improvement requires continued evaluation of work process, such as TAP analysis and development in summary to make training at DOE facilities the most cost-effective training anywhere, we need to share, challenge conventional wisdom, and seek to continuously improve.

  5. Building an Archive Backbone Extending TAP

    NASA Astrophysics Data System (ADS)

    Molinaro, M.; Apollo, P.; Knapic, C.; Smareglia, R.

    2014-05-01

    A data center (DC) willing to add VO (Virtual Observatory) capabilities to existing archival resources, or new ones, will probably face some issues regarding the constraints on the existing structure of the datasets. On the opposite direction a DC may want to give priority to VO flavored data access but maintain flexibility on proprietary or dedicated access solutions. This contribution tries to delineate a solution, feasible for both approaches, taking advantage of the IVOA (International Virtual Observatory Alliance) existing standards and, at the same time, forcing no constraint at archive generation or ingestion level. The IVOA TAP (Table Access Protocol) specification generalizes the way a set of database schemas and tables, related or not, can be deployed as a queryable resource in the framewok of the Virtual Observatory. The TAP protocol itself has, at its core, a DB schema, named TAP_SCHEMA, that actually acts as an attribute-extended information schema for the exposed set of tables; the TAP_SCHEMA, in short, describes the content of the schemas and tables, and their connections, in a VO aware flavour. It seems then quite immediate to think about pushing the generalization step a little further, i.e. to extend the TAP_SCHEMA itself to provide a more general description of an astrophysical archive (or part of it). Here we discuss on how, adding optional tables and columns to the TAP_SCHEMA, it would be possible to create an archive thin layer solution in terms of this DB schema alongside with a content manager application for it. The goal is to provide a re-usable, configurable connection between an archive's back end and front end, having the benefit of creating a VO translation layer to ease VO resource and service deployment and preserving custom data access and publishing.

  6. Tap upgrade wins praise all round.

    PubMed

    Berry, Hannah

    2011-06-01

    An ongoing upgrading of clinical handwashing facilities at its hospitals by NHS Lanarkshire is seeing the Scottish Health Board replace, in many cases, ageing basins and taps subject to Healthcare Environment Inspectorate (HEI) criticism, with standardised modules comprising a clinical basin, Horne Engineering's Optitherm thermostatic tap, and soap and towel dispensers, all mounted on a single integrated panel structure. As Home's marketing manager, Hannah Berry, explains, one of the many benefits is that the Board's Estates Department no longer needs a large "arsenal" of spare parts in stock for different fittings. PMID:21776925

  7. Detection of Pathogens Using AFM and SPR

    NASA Astrophysics Data System (ADS)

    Vaseashta, Ashok

    2005-03-01

    A priori detection of pathogens in food and water has become a subject of paramount importance. Several recent incidents have resulted in the government passing stringent regulations for tolerable amounts of contamination of food products. Identification and/or monitoring of bacterial contamination in food are critical. The conventional methods of pathogen detection require time-consuming steps to arrive disembark at meaningful measurement in a timely manner as the detection time exceeds the time in which perishable food recycles through the food chain distribution. The aim of this presentation is to outline surface plasmon resonance (SPR) and atomic force microscopy (AFM) as two methods for fast detect6ion of pathogens. Theoretical basis of SPR and experimental results of SPR and AFM on E. coli O157:H7 and prion are presented.

  8. An advanced AFM sensor for high-aspect ratio pattern profile in-line measurement

    NASA Astrophysics Data System (ADS)

    Watanabe, Masahiro; Baba, Shuichi; Nakata, Toshihiko; Kurenuma, Toru; Kuroda, Hiroshi; Hiroki, Takenori

    2006-03-01

    Design rule shrinkage and the wider adoption of new device structures such as STI, copper damascene interconnects, and deep trench structures have increased the necessity of in-line process monitoring of step heights and profiles of device structures. For monitoring active device patterns, not test patterns as in OCD, AFM is the only non-destructive 3D monitoring tool. The barriers to using AFM in-line monitoring are its slow throughput and the accuracy degradation associated with probe tip wear and spike noise caused by unwanted oscillation on the steep slopes of high-aspect-ratio patterns. Our proprietary AFM scanning method, Step in mode®, is the method best suited to measuring high-aspect-ratio pattern profiles. Because the probe is not dragged on the sample surface as in conventional AFM, the profile trace fidelity across steep slopes is excellent. Because the probe does not oscillate and hit the sample at a high frequency as in AC scanning mode, this mode is free from unwanted spurious noises on steep sample slopes and incurs extremely little probe tip wear. To fully take advantage of the above properties, we have developed an AFM sensor optimized for in-line use, which produces accurate profile data at high speeds. The control scheme we have developed for the AFM sensor, which we call "Smart Step-in", elaborately analyses the contact force signal, enabling efficient probe tip scanning and a low and stable contact force. The mechanism of the AFM sensor has been optimized for the higher scanning rate and has improved the accuracy, such as the scanning planarity, position and height accuracy, and slope angle accuracy. Our prototype AFM sensor can scan high-aspect-ratio patterns while stabilizing the contact force at 3 nN. The step height measurement repeatability was 0.8 nm (3σ). A STI-like test pattern was scanned, and the steep sidewalls with angles of 84° were measured with high fidelity and without spurious noises.

  9. Visualization of internal structure of banana starch granule through AFM.

    PubMed

    Peroni-Okita, Fernanda H G; Gunning, A Patrick; Kirby, Andrew; Simão, Renata A; Soares, Claudinéia A; Cordenunsi, Beatriz R

    2015-09-01

    Atomic force microscopy (AFM) is a high resolution technique for studying the external and internal structures of starch granules. For this purpose granules were isolated from bananas and embedded in a non-penetrating resin. To achieve image contrast of the ultrastructure, the face of the cut blocks were wetted in steam and force modulation mode imaging was used. Images of starch from green bananas showed large variation of height across the granule due to a locational specific absorption of water and swelling of amorphous regions; the data reveal that the center of the granules are structurally different and have different viscoelastic properties. Images of starches from ripe bananas showed an even greater different level of organization: absence of growth rings around the hilum; the central region of the granule is richer in amylose; very porous surface with round shaped dark structures; the size of blocklets are larger than the green fruits. PMID:26005137

  10. Characterizing Cell Mechanics with AFM and Microfluidics

    NASA Astrophysics Data System (ADS)

    Walter, N.; Micoulet, A.; Suresh, S.; Spatz, J. P.

    2007-03-01

    Cell mechanical properties and functionality are mainly determined by the cytoskeleton, besides the cell membrane, the nucleus and the cytosol, and depend on various parameters e.g. surface chemistry and rigidity, surface area and time available for cell spreading, nutrients and drugs provided in the culture medium. Human epithelial pancreatic and mammary cancer cells and their keratin intermediate filaments are the main focus of our work. We use Atomic Force Microscopy (AFM) to study cells adhering to substrates and Microfluidic Channels to probe cells in suspension, respectively. Local and global properties are extracted by varying AFM probe tip size and the available adhesion area for cells. Depth-sensing, instrumented indentation tests with AFM show a clear difference in contact stiffness for cells that are spread of controlled substrates and those that are loosely attached. Microfluidic Channels are utilized in parallel to evaluate cell deformation and ``flow resistance'', which are dependent on channel cross section, flow rate, cell nucleus size and the mechanical properties of cytoskeleton and membrane. The results from the study are used to provide some broad and quantitative assessments of the connections between cellular/subcellular mechanics and biochemical origins of disease states.

  11. Functional Imaging of Human Vestibular Cortex Activity Elicited by Skull Tap and Auditory Tone Burst

    NASA Technical Reports Server (NTRS)

    Noohi, Fatemeh; Kinnaird, Catherine; Wood, Scott; Bloomberg, Jacob; Mulavara, Ajitkumar; Seidler, Rachael

    2014-01-01

    The aim of the current study was to characterize the brain activation in response to two modes of vestibular stimulation: skull tap and auditory tone burst. The auditory tone burst has been used in previous studies to elicit saccular Vestibular Evoked Myogenic Potentials (VEMP) (Colebatch & Halmagyi 1992; Colebatch et al. 1994). Some researchers have reported that airconducted skull tap elicits both saccular and utricle VEMPs, while being faster and less irritating for the subjects (Curthoys et al. 2009, Wackym et al., 2012). However, it is not clear whether the skull tap and auditory tone burst elicit the same pattern of cortical activity. Both forms of stimulation target the otolith response, which provides a measurement of vestibular function independent from semicircular canals. This is of high importance for studying the vestibular disorders related to otolith deficits. Previous imaging studies have documented activity in the anterior and posterior insula, superior temporal gyrus, inferior parietal lobule, pre and post central gyri, inferior frontal gyrus, and the anterior cingulate cortex in response to different modes of vestibular stimulation (Bottini et al., 1994; Dieterich et al., 2003; Emri et al., 2003; Schlindwein et al., 2008; Janzen et al., 2008). Here we hypothesized that the skull tap elicits the similar pattern of cortical activity as the auditory tone burst. Subjects put on a set of MR compatible skull tappers and headphones inside the 3T GE scanner, while lying in supine position, with eyes closed. All subjects received both forms of the stimulation, however, the order of stimulation with auditory tone burst and air-conducted skull tap was counterbalanced across subjects. Pneumatically powered skull tappers were placed bilaterally on the cheekbones. The vibration of the cheekbone was transmitted to the vestibular cortex, resulting in vestibular response (Halmagyi et al., 1995). Auditory tone bursts were also delivered for comparison. To validate

  12. Deepwater cold tapping developed for repairs

    SciTech Connect

    Quir, R.

    1984-04-01

    Deep tests of cold tapping equipment for subsea pipeline repairs and line modifications have been successfully conducted in Hjeltefjorden near Bergen, Norway, in 462 ft water depth by Total Marine Norsk A/S. The operations were conducted from the Ugland-Comex 1, a DP diving support vessel, by the Kongsberg Vapenfabrikk/Comex Services joint venture. Objective of the cold tapping project was to devise a system that would avoid flooding of a subsea oil or gas pipeline during repair of the line or during modification of the line, such as adding a tee. Principle of the cold tapping method is to insert a plug on either side of the section on which work is to be conducted, thereby effectively isolating both the pipe from the seawater and the section of pipe involved from the fluid moving through the pipeline. Pipeline repair times could be cut by as much as 50% with the cold tapping method. Repairs usually involve either a wet buckle (which produces a hole in the line and forces the operator to shut down production until repairs are made) or a dry buckle, which generally is an obstruction to pigs and a weak point in the line.

  13. S-TAP Program in Elementary Education.

    ERIC Educational Resources Information Center

    Concordia Coll., Moorhead, MN.

    In September 1971, Concordia College in Minnesota developed the Self-Teacher Actualization Program (S-TAP). This program enabled junior year elementary education majors to be involved daily with the teaching of children through clinical experiences in the public schools in five curriculum areas (reading, language arts, social studies, math, and…

  14. 49 CFR 192.151 - Tapping.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Tapping. 192.151 Section 192.151 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL...

  15. TAP into Learning, Fall-Winter 2000.

    ERIC Educational Resources Information Center

    Burns, Mary; Dimock, Vicki; Martinez, Danny

    2000-01-01

    This document consists of the final three issues of "TAP into Learning" (Technology Assistance Program). The double fall issue focuses on knowledge construction and on using multimedia applications in the classroom. Contents include: "Knowledge Under Construction"; "Hegel and the Dialectic"; "Implications for Teaching and Learning"; "How Can…

  16. Tapping Epistemological Resources for Learning Physics.

    ERIC Educational Resources Information Center

    Hammer, David; Elby, Andrew

    2003-01-01

    Explores connections between naive epistemology and everyday instructional practice. Reviews examples of naive epistemologies as made up of fine-grained, context-sensitive resources. Presents strategies designed to help students tap those resources for learning introductory physics. Reflects on this work as an example of interplay between two…

  17. Ideomotor effects of pitch on continuation tapping.

    PubMed

    Ammirante, Paolo; Thompson, William F; Russo, Frank A

    2011-02-01

    The ideomotor principle predicts that perception will modulate action where overlap exists between perceptual and motor representations of action. This effect is demonstrated with auditory stimuli. Previous perceptual evidence suggests that pitch contour and pitch distance in tone sequences may elicit tonal motion effects consistent with listeners' implicit awareness of the lawful dynamics of locomotive bodies. To examine modulating effects of perception on action, participants in a continuation tapping task produced a steady tempo. Auditory tones were triggered by each tap. Pitch contour randomly and persistently varied within trials. Pitch distance between successive tones varied between trials. Although participants were instructed to ignore them, tones systematically affected finger dynamics and timing. Where pitch contour implied positive acceleration, the following tap and the intertap interval (ITI) that it completed were faster. Where pitch contour implied negative acceleration, the following tap and the ITI that it completed were slower. Tempo was faster with greater pitch distance. Musical training did not predict the magnitude of these effects. There were no generalized effects on timing variability. Pitch contour findings demonstrate how tonal motion may elicit the spontaneous production of accents found in expressive music performance. PMID:20694921

  18. Comparison of TAPS Packages for Engineering

    ERIC Educational Resources Information Center

    Sidhu, S. Manjit

    2008-01-01

    Purpose: This paper aims to present the development of technology-assisted problem solving (TAPS) packages at University Tenaga Nasional (UNITEN). The project is the further work of the development of interactive multimedia based packages targeted for students having problems in understanding the subject of engineering mechanics dynamics.…

  19. Cooling of a Tapped Granular Column

    NASA Astrophysics Data System (ADS)

    Rosato, Anthony; Zuo, Luo; Blackmore, Denis

    2013-11-01

    We present the results of a discrete element investigation of the cooling of a tapped column of uniform, inelastic spherical particles (d) as it evolves to a state of zero kinetic energy. A linear loading-unloading soft contact model is employed, while tapping is simulated by applying a half-sine pulse of amplitude a/ d and frequency f to a rigid floor supporting the column. For sufficiently energetic taps, the column dilates and then contracts over a time scale ts, which depends on the number of particles N, restitution coefficient e, as well as tap parameters (a/ d, f) . Simulation data for (1 <= N <= 50) with other parameters being held constant suggested that a time-averaged collision frequency fc scaled with N. Values of ts, determined by identifying the instant when the kinetic energy thereafter remained less than 0.001%of its maximum value, were well-correlated with the form α (e) N-1 + β (e) . Lastly, simulations were in good agreement with physical considerations, suggesting that ts should scale with (1 - e2)-1 and inversely with fc. Supported in part by NSF Grant CMMI-1029809.

  20. Project TAPS. Progress Report Number 2.

    ERIC Educational Resources Information Center

    Desch, S. H.; Stolurow, L. M.

    TRIGEM, a computer-assisted instruction (CAI) course developed as a part of Project TAPS (Teaching Anatomy with Programed Schematics) is designed to teach the anatomy of the maxillary division of the trigeminal nerve. This course is currently operational on the Harvard CAI System which uses an IBM S 360/Model 65 as the central processor, either…

  1. 49 CFR 192.151 - Tapping.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... of cracks and have good threads; and (2) A 11/4-inch (32 millimeters) tap may be made in a 4-inch... Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL AND OTHER...

  2. Evaluating a Tap Water Contamination Incident Attributed to Oil Contamination by Nontargeted Screening Strategies.

    PubMed

    Wang, Beili; Wan, Yi; Zheng, Guomao; Hu, Jianying

    2016-03-15

    The present study applied nontargeted screening techniques as a novel approach to evaluate the tap water samples collected during the "4.11" tap water pollution incident occurred on April 11, 2014 in Lanzhou in west China. Multivariate analysis (PCA and OPLS-DA) of about 3000 chemical features obtained in extracts of tap water samples by ultrahigh-pressure liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) analysis showed significantly different chemical profiles in tap water from pollution regions versus reference regions during the event. These different chemical profiles in samples from different regions were not observed in samples collected during the nonpollution period. The compounds responsible for the differences in profiles between regions were identified as naphthenic acids (NAs) and oxidized NAs (oxy-NAs) after the sample extracts underwent bromination to explore saturations, dansylation to identify hydroxylations and corresponding MS/MS mode analysis. A consistent finding was further observed in the targeted analysis of NA mixtures, demonstrating that the Lanzhou "4.11" tap water pollution incident could be attributed to oil spill pollution, and NA mixtures would be a marker for oil contamination. Such evaluations can help to rapidly discriminate pollution sources in accidental pollution events and contribute to regular water monitoring management of water safety issues. PMID:26862992

  3. BOREAS AFM-6 Surface Meteorological Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) collected surface meteorological data from 21 May to 20 Sep 1994 near the Southern Study Area-Old Jack Pine (SSA-OJP) tower site. The data are in tabular ASCII files. The surface meteorological data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  4. Measurement of Bulk and Tapped Density on Pharmaceutical Powders

    NASA Astrophysics Data System (ADS)

    Goldfarb, David; Ramachandruni, Hanu

    2003-11-01

    The bulk and tapped density of pharmaceutical powders are often measured for processability. The tapped density is measured for two primary purposes: (i) the tapped value is more reproducibly measured than the bulk value, and (ii) the "flowability" of a powder is inferred from the ratio of these two measured densities. The density ratio method is compared to flowability measurements on a Johanson Flow Indicizer. These methods are evaluated for monodisperse glass beads as well as for common pharmaceutical excipients and blends. The "tapped" density of a pharmaceutical powder is determined using a tapped density tester, which is set to tap the powder at a fixed impact force and frequency. The methods for measurement in the U.S. pharmaceutical industry are specified in the U.S. Pharmacopeia (USP). Tapped density by the USP method is determined by a linear progression of the number of taps. In light of experiments performed over the past decade, exhibiting a slow relaxation approach to the final packing state (logarithmic with the number of taps), the tapped density measured with the USP method is further explored. Additionally, the dependence of the tapped density on the conditions specified in the USP method, e.g., sample size and time separation between taps, is examined.

  5. Tapping the wind's power over water

    SciTech Connect

    Greenberger, L.S.

    1992-03-15

    This article describes a new wind power concept. Tethered wind turbines are flown at a height of one to three kilometers above the Massachusetts coast, where they would tap the strong coastal winds and deliver 17 MW of power each to substations on the shore. The cost is about 6.3 cents per kw, but the load factor of 57% justifies the higher cost.

  6. What's Wrong with the Tap? Examining Perceptions of Tap Water and Bottled Water at Purdue University

    NASA Astrophysics Data System (ADS)

    Saylor, Amber; Prokopy, Linda Stalker; Amberg, Shannon

    2011-09-01

    The environmental impacts of bottled water prompted us to explore drinking water choices at Purdue University, located in West Lafayette, IN. A random sample of 2,045 Purdue University students, staff, and faculty was invited to participate in an online survey. The survey assessed current behaviors as well as perceived barriers and benefits to drinking tap water versus bottled water. 677 surveys were completed for a response rate of 33.1%. We then conducted qualitative interviews with a purposive sample of university undergraduates ( n = 21) to obtain contextual insights into the survey results and the beliefs of individuals with a variety of drinking water preferences. This study revealed that women drink disproportionately more bottled water then men while undergraduate students drink more than graduate students, staff and faculty. The study also uncovered a widespread belief that recycling eliminates the environmental impacts of bottled water. Important barriers to drinking tap water at Purdue include: perceived risks from tap water and the perceived safety of bottled water, preferring the taste of bottled water, and the convenience of drinking bottled water. The qualitative interviews revealed that drinking water choices can be influenced by several factors—especially whether individuals trust tap water to be clean—but involve varying levels of complexity. The implications of these results for social marketing strategies to promote tap water are discussed.

  7. Studying post-etching silicon crystal defects on 300mm wafer by automatic defect review AFM

    NASA Astrophysics Data System (ADS)

    Zandiatashbar, Ardavan; Taylor, Patrick A.; Kim, Byong; Yoo, Young-kook; Lee, Keibock; Jo, Ahjin; Lee, Ju Suk; Cho, Sang-Joon; Park, Sang-il

    2016-03-01

    light scattering. Likewise, SEM cannot be used effectively for post-inspection defect review and classification of these very shallow types of defects. To verify and obtain accurate shape and three-dimensional information of those defects, automatic defect review AFM (ADR AFM) is utilized for accurate locating and imaging of DOI. In ADR AFM, non-contact mode imaging is used for non-destructive characterization and preserving tip sharpness for data repeatability and reproducibility. Locating DOI and imaging are performed automatically with a throughput of many defects per hour. Topography images of DOI has been collected and compared with SEM images. The ADR AFM has been shown as a non-destructive metrology tool for defect review and obtaining three-dimensional topography information.

  8. [AFM fishing of proteins under impulse electric field].

    PubMed

    Ivanov, Yu D; Pleshakova, T O; Malsagova, K A; Kaysheva, A L; Kopylov, A T; Izotov, A A; Tatur, V Yu; Vesnin, S G; Ivanova, N D; Ziborov, V S; Archakov, A I

    2016-05-01

    A combination of (atomic force microscopy)-based fishing (AFM-fishing) and mass spectrometry allows to capture protein molecules from solutions, concentrate and visualize them on an atomically flat surface of the AFM chip and identify by subsequent mass spectrometric analysis. In order to increase the AFM-fishing efficiency we have applied pulsed voltage with the rise time of the front of about 1 ns to the AFM chip. The AFM-chip was made using a conductive material, highly oriented pyrolytic graphite (HOPG). The increased efficiency of AFM-fishing has been demonstrated using detection of cytochrome b5 protein. Selection of the stimulating pulse with a rise time of 1 ns, corresponding to the GHz frequency range, by the effect of intrinsic emission from water observed in this frequency range during water injection into the cell. PMID:27562998

  9. Accurate Calibration and Uncertainty Estimation of the Normal Spring Constant of Various AFM Cantilevers

    PubMed Central

    Song, Yunpeng; Wu, Sen; Xu, Linyan; Fu, Xing

    2015-01-01

    Measurement of force on a micro- or nano-Newton scale is important when exploring the mechanical properties of materials in the biophysics and nanomechanical fields. The atomic force microscope (AFM) is widely used in microforce measurement. The cantilever probe works as an AFM force sensor, and the spring constant of the cantilever is of great significance to the accuracy of the measurement results. This paper presents a normal spring constant calibration method with the combined use of an electromagnetic balance and a homemade AFM head. When the cantilever presses the balance, its deflection is detected through an optical lever integrated in the AFM head. Meanwhile, the corresponding bending force is recorded by the balance. Then the spring constant can be simply calculated using Hooke’s law. During the calibration, a feedback loop is applied to control the deflection of the cantilever. Errors that may affect the stability of the cantilever could be compensated rapidly. Five types of commercial cantilevers with different shapes, stiffness, and operating modes were chosen to evaluate the performance of our system. Based on the uncertainty analysis, the expanded relative standard uncertainties of the normal spring constant of most measured cantilevers are believed to be better than 2%. PMID:25763650

  10. Single-Molecule Studies of Integrins by AFM-Based Force Spectroscopy on Living Cells

    NASA Astrophysics Data System (ADS)

    Eibl, Robert H.

    The characterization of cell adhesion between two living cells at the single-molecule level, i.e., between one adhesion receptor and its counter-receptor, appears to be an experimental challenge. Atomic force microscopy (AFM) can be used in its force spectroscopy mode to determine unbinding forces of a single pair of adhesion receptors, even with a living cell as a probe. This chapter provides an overview of AFM force measurements of the integrin family of cell adhesion receptors and their ligands. A focus is given to major integrins expressed on leukocytes, such as lymphocyte function-associated antigen 1 (LFA-1) and very late antigen 4 (VLA-4). These receptors are crucial for leukocyte trafficking in health and disease. LFA-1 and VLA-1 can be activated within the bloodstream from a low-affinity to a high-affinity receptor by chemokines in order to adhere strongly to the vessel wall before the receptor-bearing leukocytes extravasate. The experimental considerations needed to provide near-physiological conditions for a living cell and to be able to measure adequate forces at the single-molecule level are discussed in detail. AFM technology has been developed into a modern and extremely sensitive tool in biomedical research. It appears now that AFM force spectroscopy could enter, within a few years, medical applications in diagnosis and therapy of cancer and autoimmune diseases.

  11. BOREAS AFM-06 Mean Temperature Profile Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) tower from 21 May 1994 to 20 Sep 1994. The data set provides temperature profiles at 15 heights, containing the variables of virtual temperature, vertical velocity, the speed of sound, and w-bar. The data are stored in tabular ASCII files. The mean temperature profile data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  12. BOREAS AFM-6 Boundary Layer Height Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) site. This data set provides boundary layer height information over the site. The data were collected from 21 May 1994 to 20 Sep 1994 and are stored in tabular ASCII files. The boundary layer height data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  13. BOREAS AFM-06 Mean Wind Profile Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Administration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) tower from 21 May 1994 to 20 Sep 1994. The data set provides wind profiles at 38 heights, containing the variables of wind speed; wind direction; and the u-, v-, and w-components of the total wind. The data are stored in tabular ASCII files. The mean wind profile data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  14. Functional Imaging of Human Vestibular Cortex Activity Elicited by Skull Tap and Auditory Tone Burst

    NASA Technical Reports Server (NTRS)

    Noohi, F.; Kinnaird, C.; Wood, S.; Bloomberg, J.; Mulavara, A.; Seidler, R.

    2016-01-01

    The current study characterizes brain activation in response to two modes of vestibular stimulation: skull tap and auditory tone burst. The auditory tone burst has been used in previous studies to elicit either the vestibulo-spinal reflex (saccular-mediated colic Vestibular Evoked Myogenic Potentials (cVEMP)), or the ocular muscle response (utricle-mediated ocular VEMP (oVEMP)). Some researchers have reported that air-conducted skull tap elicits both saccular and utricle-mediated VEMPs, while being faster and less irritating for the subjects. However, it is not clear whether the skull tap and auditory tone burst elicit the same pattern of cortical activity. Both forms of stimulation target the otolith response, which provides a measurement of vestibular function independent from semicircular canals. This is of high importance for studying otolith-specific deficits, including gait and balance problems that astronauts experience upon returning to earth. Previous imaging studies have documented activity in the anterior and posterior insula, superior temporal gyrus, inferior parietal lobule, inferior frontal gyrus, and the anterior cingulate cortex in response to different modes of vestibular stimulation. Here we hypothesized that skull taps elicit similar patterns of cortical activity as the auditory tone bursts, and previous vestibular imaging studies. Subjects wore bilateral MR compatible skull tappers and headphones inside the 3T GE scanner, while lying in the supine position, with eyes closed. Subjects received both forms of the stimulation in a counterbalanced fashion. Pneumatically powered skull tappers were placed bilaterally on the cheekbones. The vibration of the cheekbone was transmitted to the vestibular system, resulting in the vestibular cortical response. Auditory tone bursts were also delivered for comparison. To validate our stimulation method, we measured the ocular VEMP outside of the scanner. This measurement showed that both skull tap and auditory

  15. TAP 2: Performance-Based Training Manual

    SciTech Connect

    Not Available

    1993-08-01

    Cornerstone of safe operation of DOE nuclear facilities is personnel performing day-to-day functions which accomplish the facility mission. Performance-based training is fundamental to the safe operation. This manual has been developed to support the Training Accreditation Program (TAP) and assist contractors in efforts to develop performance-based training programs. It provides contractors with narrative procedures on performance-based training that can be modified and incorporated for facility-specific application. It is divided into sections dealing with analysis, design, development, implementation, and evaluation.

  16. Segregation in Fluidized versus Tapped Packs

    NASA Astrophysics Data System (ADS)

    Tarzia, Marco; Fierro, Annalisa; Nicodemi, Mario; Coniglio, Antonio

    2004-11-01

    We compare the predictions of two different statistical mechanics approaches, corresponding to different physical measurements, proposed to describe binary granular mixtures subjected to some external driving (continuous shaking or tap dynamics). In particular we analytically solve at a mean field level the partition function of a simple hard sphere lattice model under gravity and focus on the phenomenon of size segregation. We find that the two approaches lead to similar results and seem to coincide in the limit of very low shaking amplitude. However, they give different predictions of the crossovers from Brazil nut effect to reverse Brazil nut effect with respect to the shaking amplitude, which could be detected experimentally.

  17. AFM study of mineral wettability with reservoir oils.

    PubMed

    Kumar, K; Dao, E; Mohanty, K K

    2005-09-01

    Wettability plays a key role in determining fluid distributions and consequently the multiphase flow and transport in petroleum reservoirs. Many crude oils have polar organic components that collect at oil-water interfaces and can adsorb onto the mineral surface if the brine film breaks, rendering the medium oil-wet or mixed-wet. Mica and silica surfaces have been aged with brine and crude oils to induce oil component adsorption. Bulk oil is eventually replaced by water in these experiments by washing with common solvents without ever drying the mineral surface. The organic deposit on the mineral surface is studied by atomic force microscopy in the tapping mode under water. Drying the surface during the removal of bulk oil induces artifacts; it is essential to keep the surface wet at all times before atomic force microscopy or contact angle measurement. As the mean thickness of the organic deposit increases, the oil-water contact angle increases. The organic deposits left behind after extraction of oil by common aromatic solvents used in core studies, such as toluene and decalin, are thinner than those left behind by non-aromatic solvents, such as cyclohexane. The force of adhesion with a probe sphere for minerals aged with just the asphaltene fraction is similar to that of the whole oil. The force of adhesion for the minerals aged with just the resin fraction is the highest of all SARA (saturates, aromatics, resins, and asphaltenes) fractions. PMID:16009229

  18. Calibration of AFM cantilever stiffness: a microfabricated array of reflective springs.

    PubMed

    Cumpson, P J Peter J; Zhdan, Peter; Hedley, John

    2004-08-01

    Calibration of the spring constant of atomic force microscope (AFM) cantilevers is necessary for the measurement of nanonewton and piconewton forces, which are critical to analytical applications of AFM in the analysis of polymer surfaces, biological structures and organic molecules. We have developed a compact and easy-to-use reference standard for this calibration. The new artifact consists of an array of 12 dual spiral-cantilever springs, each supporting a mirrored polycrystalline silicon disc of 160 microm in diameter. These devices were fabricated by a three-layer polysilicon surface micromachining method, including a reflective layer of gold on chromium. We call such an array a Microfabricated Array of Reference Springs (MARS). These devices have a number of advantages. Cantilever calibration using this device is straightforward and rapid. The devices have very small inertia, and are therefore resistant to shock and vibration. This means they need no careful treatment except reasonably clean laboratory conditions. The array spans the range of spring constant from around 0.16 to 11 N/m important in AFM, allowing almost all contact-mode AFM cantilevers to be calibrated easily and rapidly. Each device incorporates its own discrete gold mirror to improve reflectivity. The incorporation of a gold mirror both simplifies calibration of the devices themselves (via Doppler velocimetry) and allows interferometric calibration of the AFM z-axis using the apparent periodicity in the force-distance curve before contact. Therefore, from a single force-distance curve, taking about one second to acquire, one can calibrate the cantilever spring constant and, optionally, the z-axis scale. These are all the data one needs to make accurate and reliable force measurements. PMID:15231316

  19. A Wide Dynamic Range Tapped Linear Array Image Sensor

    NASA Astrophysics Data System (ADS)

    Washkurak, William D.; Chamberlain, Savvas G.; Prince, N. Daryl

    1988-08-01

    Detectors for acousto-optic signal processing applications require fast transient response as well as wide dynamic range. There are two major choices of detectors: conductive or integration mode. Conductive mode detectors have an initial transient period before they reach then' i equilibrium state. The duration of 1 his period is dependent on light level as well as detector capacitance. At low light levels a conductive mode detector is very slow; response time is typically on the order of milliseconds. Generally. to obtain fast transient response an integrating mode detector is preferred. With integrating mode detectors. the dynamic range is determined by the charge storage capability of the tran-sport shift registers and the noise level of the image sensor. The conventional net hod used to improve dynamic range is to increase the shift register charge storage capability. To achieve a dynamic range of fifty thousand assuming two hundred noise equivalent electrons, a charge storage capability of ten million electrons would be required. In order to accommodate this amount of charge. unrealistic shift registers widths would be required. Therefore, with an integrating mode detector it is difficult to achieve a dynamic range of over four orders of magnitude of input light intensity. Another alternative is to solve the problem at the photodetector aml not the shift, register. DALSA's wide dynamic range detector utilizes an optimized, ion implant doped, profiled MOSFET photodetector specifically designed for wide dynamic range. When this new detector operates at high speed and at low light levels the photons are collected and stored in an integrating fashion. However. at bright light levels where transient periods are short, the detector switches into a conductive mode. The light intensity is logarithmically compressed into small charge packets, easily carried by the CCD shift register. As a result of the logarithmic conversion, dynamic ranges of over six orders of

  20. Differing Dynamics of Intrapersonal and Interpersonal Coordination: Two-finger and Four-Finger Tapping Experiments

    PubMed Central

    Kodama, Kentaro; Furuyama, Nobuhiro; Inamura, Tetsunari

    2015-01-01

    Finger-tapping experiments were conducted to examine whether the dynamics of intrapersonal and interpersonal coordination systems can be described equally by the Haken—Kelso—Bunz model, which describes inter-limb coordination dynamics. This article reports the results of finger-tapping experiments conducted in both systems. Two within-subject factors were investigated: the phase mode and the number of fingers. In the intrapersonal experiment (Experiment 1), the participants were asked to tap, paced by a gradually hastening auditory metronome, looking at their fingers moving, using the index finger in the two finger condition, or the index and middle finger in the four-finger condition. In the interpersonal experiment (Experiment 2), pairs of participants performed the task while each participant used the outside hand, tapping with the index finger in the two finger condition, or the index and middle finger in the four-finger condition. Some results did not agree with the HKB model predictions. First, from Experiment 1, no significant difference was observed in the movement stability between the in-phase and anti-phase modes in the two finger condition. Second, from Experiment 2, no significant difference was found in the movement stability between the in-phase and anti-phase mode in the four-finger condition. From these findings, different coordination dynamics were inferred between intrapersonal and interpersonal coordination systems against prediction from the previous studies. Results were discussed according to differences between intrapersonal and interpersonal coordination systems in the availability of perceptual information and the complexity in the interaction between limbs derived from a nested structure. PMID:26070119

  1. Study of relaxation and transport processes by means of AFM based dielectric spectroscopy

    SciTech Connect

    Miccio, Luis A.

    2014-05-15

    Since its birth a few years ago, dielectric spectroscopy studies based on atomic force microscopy (AFM) have gained a growing interest. Not only the frequency and temperature ranges have become broader since then but also the kind of processes that can be studied by means of this approach. In this work we analyze the most adequate experimental setup for the study of several dielectric processes with a spatial resolution of a few nanometers by using force mode AFM based dielectric spectroscopy. Proof of concept experiments were performed on PS/PVAc blends and PMMA homopolymer films, for temperatures ranging from 300 to 400 K. Charge transport processes were also studied by this approach. The obtained results were analyzed in terms of cantilever stray contribution, film thickness and relaxation strength. We found that the method sensitivity is strongly coupled with the film thickness and the relaxation strength, and that it is possible to control it by using an adequate experimental setup.

  2. Probing of local dissolution of Al-alloys in chloride solutions by AFM and SECM

    NASA Astrophysics Data System (ADS)

    Davoodi, A.; Pan, J.; Leygraf, C.; Norgren, S.

    2006-05-01

    Local dissolution of Al alloys was probed in situ in chloride solutions by using atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). Preferential dissolution in the boundary region between some intermetallic particles (IMPs) and alloy matrix, and trench formation around large IMPs during free immersion and under electrochemical anodic polarization were observed, which indicate different dissolution behavior associated to different types of IMPs. Moreover, by using an integrated AFM/SECM system with a dual mode cantilever/microelectrode probe, simultaneous probing of electrochemical active sites and topographic changes over the same area was performed with sub-micron resolution. This allowed the ongoing localized corrosion processes related to the IMP to be revealed.

  3. Multiple-bipolar-tap tunable spectrum sliced microwave photonic filter.

    PubMed

    Chen, Tong; Yi, Xiaoke; Huang, Thomas; Minasian, Robert A

    2010-12-01

    A spectrum sliced microwave photonic signal processor structure, which is all-fiber based and features simplicity, together with the ability to realize tunability, reconfigurability, bipolar taps, and multiple-tap rf filtering, is presented. It is based on thermally controlled optical slicing filters induced into two linearly chirped fiber Bragg gratings. Experimental results demonstrate the realization of versatile microwave photonic filters with frequency tunable, reconfiguration, and bipolar-tap generation capabilities. PMID:21124570

  4. Integration of small taps into (existing) HVDC links

    SciTech Connect

    Bahrman, M.; Baker, M.; Bowles, J.

    1995-07-01

    Tapping of HVDC lines to serve intermediate loads or to pick up dispersed generation has always presented formidable technical and economic challenges to transmission planners and to system designers. These challenges have been particularly daunting when the power rating of the tap is small compared to that of the main terminals. This document provides transmission planners with various factors which need to be considered in evaluating the feasibility of tapping existing HVDC transmission lines or in developing alternatives for potential new transmission schemes.

  5. Microrheology using a custom-made AFM

    NASA Astrophysics Data System (ADS)

    Kosgodagan Acharige, Sebastien; Benzaquen, Michael; Steinberger, Audrey

    In the past few years, a new method was developed to measure local properties of liquids (X. Xiong et al., Phys. Rev. E 80, 2009). This method consists of gluing a micron-sized glass fiber at the tip of an AFM cantilever and probing the liquid with it. In ENS Lyon, this method was perfected (C. Devailly et al., EPL, 106 5, 2014) with the help of an interferometer developped in the same laboratory (L. Bellon et al., Opt. Commun. 207 49, 2002 and P. Paolino et al., Rev. Sci. Instrum. 84, 2013), which background noise can reach 10-14 m /√{ Hz } . This method allows us to measure a wide range of viscosities (1 mPa . s to 500 mPa . s) of transparent and opaque fluids using a small sample volume ( 5 mL). In this presentation, I will briefly describe the interferometer developped in ENS Lyon, then explain precisely the microrheology measurements and then compare the experimental results to a model developped by M. Benzaquen. This work is supported financially by the ANR project NANOFLUIDYN (Grant Number ANR-13-BS10-0009).

  6. BOREAS AFM-07 SRC Surface Meteorological Data

    NASA Technical Reports Server (NTRS)

    Osborne, Heather; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Young, Kim; Wittrock, Virginia; Shewchuck, Stan; Smith, David E. (Technical Monitor)

    2000-01-01

    The Saskatchewan Research Council (SRC) collected surface meteorological and radiation data from December 1993 until December 1996. The data set comprises Suite A (meteorological and energy balance measurements) and Suite B (diffuse solar and longwave measurements) components. Suite A measurements were taken at each of ten sites, and Suite B measurements were made at five of the Suite A sites. The data cover an approximate area of 500 km (North-South) by 1000 km (East-West) (a large portion of northern Manitoba and northern Saskatchewan). The measurement network was designed to provide researchers with a sufficient record of near-surface meteorological and radiation measurements. The data are provided in tabular ASCII files, and were collected by Aircraft Flux and Meteorology (AFM)-7. The surface meteorological and radiation data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  7. Does an auditory distractor sequence affect self-paced tapping?

    PubMed

    Repp, Bruno H

    2006-01-01

    This study investigated whether an auditory distractor (D) sequence affects the timing of self-paced finger tapping. To begin with, Experiment 1 replicated earlier findings by showing that, when taps are synchronized with an isochronous auditory target (T) sequence, an isochronous D sequence of different tempo and pitch systematically modulates the tap timing. The extent of the modulation depended on the relative intensity of the T and D tones, but not on their pitch distance. Experiment 2 then used a synchronization-continuation paradigm in which D sequences of different tempi were introduced only during continuation tapping. Although the D sequences rarely captured the taps completely, they did increase the tapping variability and deviations from the correct tempo. Furthermore, they eliminated the negative correlation between successive inter-tap intervals and led to intermittent phase locking when the tapping period was close to the period of the D sequence. These distractor effects occurred regardless of whether or not the taps generated auditory feedback tones. The distractor effects thus depend neither on the intention to synchronize with a T sequence nor on the simultaneous perception of two auditory sequences. Rather, they seem to reflect a basic attraction of rhythmic movement to auditory rhythms. PMID:16098944

  8. Spinal anesthesia in a caesarian case after dry tap.

    PubMed

    Das, Hridoy Kumar; Gunjal, M K; Toshikhane, Hemant D

    2014-01-01

    The case report here is a case of cesarean operation under subarachnoid block, which resulted after a failed lumber puncture, known to be "dry tap." The result is that it was uneventful surgery without any additive anesthetics being required after injecting 2.2 ml Bupivacaine 0.5% (H). Although cases have been reported with mixed experiences of dry tap and different causes are also explained, but still there is a need to find few other reasons for "dry tap." Hence, thought to present the case for putting forward a question that if there is any more cause for dry tap. PMID:25886116

  9. Brain activities during synchronized tapping task.

    PubMed

    Hiroyasu, Tomoyuki; Murakami, Akiho; Mao Gto; Yokouchi, Hisatake

    2015-08-01

    This study aims to investigate how people process information about other people to determine a response during human-to-human cooperative work. As a preliminary study, the mechanism of cooperative work was examined using interaction between a machine and a human. This machine was designed to have an "other person" model that simulates an emotional model of another person. The task performed in the experiment was a synchronized tapping task. Two models were prepared for this experiment, a simple model that does not employ the other person model and a synchronized model that employs the other person model. Subjects performed cooperative work with these machines. During the experiment, brain activities were measured using functional near-infrared spectroscopy. It was observed that the left inferior frontal gyrus was activated more with the synchronized model than the simple model. PMID:26737670

  10. Tapping into the Energy of Black Holes

    NASA Astrophysics Data System (ADS)

    Motl, Patrick M.; Lenher, L.; Liebling, S.; Palenzuela, C.; Neilsen, D.; Hirschmann, E.

    2012-01-01

    The extraction of rotational energy from a spinning black hole via the Blandford-Znajek mechanism has long been understood as an important component in models to explain energetic jets from compact astrophysical sources. Here we show more generally that the kinetic energy of the black hole, both rotational and translational, can be tapped, thereby producing even more luminous jets powered by the interaction of the black hole with its surrounding plasma. We study the resulting Poynting jet that arises from single boosted black holes and binary black hole systems. In the latter case, we find that increasing the orbital angular momenta of the system and/or the spins of the individual black holes results in an enhanced Poynting flux.

  11. Calibration Testing of Network Tap Devices

    SciTech Connect

    Popovsky, Barbara; Chee, Brian; Frincke, Deborah A.

    2007-11-14

    Abstract: Understanding the behavior of network forensic devices is important to support prosecutions of malicious conduct on computer networks as well as legal remedies for false accusations of network management negligence. Individuals who seek to establish the credibility of network forensic data must speak competently about how the data was gathered and the potential for data loss. Unfortunately, manufacturers rarely provide information about the performance of low-layer network devices at a level that will survive legal challenges. This paper proposes a first step toward an independent calibration standard by establishing a validation testing methodology for evaluating forensic taps against manufacturer specifications. The methodology and the theoretical analysis that led to its development are offered as a conceptual framework for developing a standard and to "operationalize" network forensic readiness. This paper also provides details of an exemplar test, testing environment, procedures and results.

  12. Segmental calibration for commercial AFM in vertical direction

    NASA Astrophysics Data System (ADS)

    Shi, Yushu; Gao, Sitian; Lu, Mingzhen; Li, Wei; Xu, Xuefang

    2013-01-01

    Atomic force microscopy (AFM) is most widely applied in scientific research and industrial production. AFM is a scanning probe imaging and measuring device, useful for physical and chemical studies. Depends on its basic structure, microscopic surface pattern can be measured and captured by mechanically scanning. Its vertical and horizon resolution can reach to 0.01nm and 0.1nm. Commonly the measurement values of commercial AFM are directly from scanning piezoelectric tube, so that it not a traceable value. In order to solve the problem of commercial AFM's traceability, step height standard references are applied to calibrate the piezoelectric ceramic housing in scanning tube. All of the serial of step height standard references, covering the commercial AFM vertical scale, are calibrated by Metrology AFM developed by National Institute of Metrology (NIM), China. Three interferometers have been assembled in its XYZ axis, therefore the measurement value can directly trace to laser wavelength. Because of nonlinear characteristic of PZT, the method of segmental calibration is proposed. The measurement scale can be divided into several subsections corresponding to the calibrated values of the series of step height standards references. By this method the accuracy of measurements can be ensured in each segment measurement scale and the calibration level of the whole instrument can be promoted. In order to get a standard step shape by commercial AFM, substrate removal method is applied to deal with the bow shape problem.

  13. Horizontal tapping furnace and method of operation

    SciTech Connect

    Wunsche, E.R.

    1987-07-14

    A metallurgical furnace is described including: a furnace floor and a furnace wall means extending generally upwardly about the floor, the furnace having a vertical axis and a horizontal axis, means mounting the furnace for pivotal tilting movement about the horizontal axis between a non-tilted, normal upright position, and a tilted discharge position with the furnace tilted less than 15/sup 0/ to the vertical axis; a hearth zone defined between the floor and wall means adapted to house a bath of liquid metal of predetermined volume, the hearth zone having an upper end defining a predetermined upper level for the bath and for a layer of liquid slag floating on the upper level, when the furnace is in a non-tilted, normal upright position; the hearth zone having a lower end adjacent the floor, a tapping passage extending through the wall means from a liquid metal discharge outlet at an outer end into the lower end of the hearth zone, at an inner end, the discharge outlet being defined by an outwardly facing passage wall and the passage at the outer end; the tapping passage disposed generally parallel to the horizontal axis and vertically below the predetermined upper level, when the furnace is in the non-tilted, normal, upright position; a discharge outlet closure having a closure surface and pivotally mounted externally of the passage for pivotal to and for movement towards and away from the furnace wall means between a first position. The closure surface engages the passage wall at the outer end to fully close the discharge outlet, and a second position spaced apart from the passage wall.

  14. TAPS repair shows value of deformation monitoring

    SciTech Connect

    Simmons, G.G.; Ferrell, J.F.

    1986-04-07

    For Arctic pipelines, especially those built in river and floodplain areas, a monitoring system is essential for detecting impending pipe damage. This was a major lesson derived from last year's repair and rerouting of a section of the Trans-Alaska Pipeline (TAPS) at milepost (mp) 200. The line at this point crosses a river and floodplain area in which any surface evidence of pipe damage is obliterated, thus making ground surface conditions unreliable indicators of pipe settlement. The wintertime repair project, with rerouted pipe of about 4,000 ft long, cost $27 million. The affected pipe was buried beneath the main channel of the Dietrich River, 200.6 miles from the beginning of the pipeline at Prudhoe Bay, and 84 miles above the Arctic Circle. As part of Alyeska's continuing monitoring program, a corrosion and deformation (C/D) pig traverses the TAPS pipe at regular intervals. This pig has proven helpful in locating places where excessive settlement has caused deformation of the pipe. The C/D pig detects pipe diameter changes as small as 0.25 in. The radial and longitudinal locations of the pipe change have proven quite accurate. A review of the results of the June 1984 C/D pig run revealed a pipe wall ovality anomaly with a sinusoidal shape indicating a wrinkle. This wrinkle was small when compared with other wrinkles Alyeska had found and subsequently repaired. A comparison of previous C/D pig runs for this location revealed a wrinkle with an amplitude of 0.25 in. which had developed in previously smooth pipe in the space of a year.

  15. Graphite, graphene on SiC, and graphene nanoribbons: Calculated images with a numerical FM-AFM

    PubMed Central

    Castanié, Fabien; Nony, Laurent; Gauthier, Sébastien

    2012-01-01

    Summary Background: Characterization at the atomic scale is becoming an achievable task for FM-AFM users equipped, for example, with a qPlus sensor. Nevertheless, calculations are necessary to fully interpret experimental images in some specific cases. In this context, we developed a numerical AFM (n-AFM) able to be used in different modes and under different usage conditions. Results: Here, we tackled FM-AFM image calculations of three types of graphitic structures, namely a graphite surface, a graphene sheet on a silicon carbide substrate with a Si-terminated surface, and finally, a graphene nanoribbon. We compared static structures, meaning that all the tip and sample atoms are kept frozen in their equilibrium position, with dynamic systems, obtained with a molecular dynamics module allowing all the atoms to move freely during the probe oscillations. Conclusion: We found a very good agreement with experimental graphite and graphene images. The imaging process for the deposited nanoribbon demonstrates the stability of our n-AFM to image a non-perfectly planar substrate exhibiting a geometrical step as well as a material step. PMID:22497004

  16. Raman and AFM study of gamma irradiated plastic bottle sheets

    SciTech Connect

    Ali, Yasir; Kumar, Vijay; Dhaliwal, A. S.; Sonkawade, R. G.

    2013-02-05

    In this investigation, the effects of gamma irradiation on the structural properties of plastic bottle sheet are studied. The Plastic sheets were exposed with 1.25MeV {sup 60}Co gamma rays source at various dose levels within the range from 0-670 kGy. The induced modifications were followed by micro-Raman and atomic force microscopy (AFM). The Raman spectrum shows the decrease in Raman intensity and formation of unsaturated bonds with an increase in the gamma dose. AFM image displays rough surface morphology after irradiation. The detailed Raman analysis of plastic bottle sheets is presented here, and the results are correlated with the AFM observations.

  17. AFM Studies of Conformational Changes in Proteins and Peptides

    NASA Astrophysics Data System (ADS)

    Ploscariu, Nicoleta; Sukthankar, Pinakin; Tomich, John; Szoszkiewicz, Robert

    2015-03-01

    Here, we present estimates of molecular stiffness and mechanical energy dissipation factors for some examples of proteins and peptides. The results are obtained from AFM force spectroscopy measurements. To determine molecular stiffness and mechanical energy dissipation factors we developed a model based on measuring several resonance frequencies of an AFM cantilever in contact with either single protein molecule or peptides adsorbed on arbitrary surface. We used compliant AFM cantilevers with a small aspect ratio - a ratio of length to width - in air and in liquid, including biologically relevant phosphate buffered saline medium. Department of Physics.

  18. 49 CFR 192.627 - Tapping pipelines under pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Tapping pipelines under pressure. 192.627 Section 192.627 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS... under pressure. Each tap made on a pipeline under pressure must be performed by a crew qualified to...

  19. 49 CFR 192.627 - Tapping pipelines under pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Tapping pipelines under pressure. 192.627 Section 192.627 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS... under pressure. Each tap made on a pipeline under pressure must be performed by a crew qualified to...

  20. 49 CFR 192.627 - Tapping pipelines under pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Tapping pipelines under pressure. 192.627 Section 192.627 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS... under pressure. Each tap made on a pipeline under pressure must be performed by a crew qualified to...

  1. 49 CFR 192.627 - Tapping pipelines under pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Tapping pipelines under pressure. 192.627 Section 192.627 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS... under pressure. Each tap made on a pipeline under pressure must be performed by a crew qualified to...

  2. The mineral content of tap water in United States households

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The composition of tap water contributes to dietary intake of minerals. The USDA’s Nutrient Data Laboratory (NDL) conducted a study of the mineral content of residential tap water, to generate current data for the USDA National Nutrient Database. Sodium, potassium, calcium, magnesium, iron, copper...

  3. Water use and time analysis in ablution from taps

    NASA Astrophysics Data System (ADS)

    Zaied, Roubi A.

    2016-04-01

    There is a lack of water resources and an extreme use of potable water in our Arab region. Ablution from taps was studied since it is a repeated daily activity that consumes more water. Five different tap types are investigated for water consumption fashions including traditional mixing tap and automatic tap. Analyzing 100 experimental observations revealed that 22.7-28.8 % of ablution water is used for washing of feet and the largest water waste occurs during washing of face portions. Moreover, 30-47 % amount of water consumed in ablution from taps is wasted which can be saved if tap releases water only at moments of need. The push-type tap is being spread recently especially in airports. If it is intended for use in ablution facilities, batch duration and volume must be tuned. When each batch is 0.25 L of water and lasts for 3 s, 3 L are sufficient for one complete ablution in average which means considerable saving. A cost-benefit model is proposed for using different tap types and an economic feasibility study is performed on a case study. This analysis can help us to design better ablution systems.

  4. Regulation of skin aging and heart development by TAp63.

    PubMed

    Paris, M; Rouleau, M; Pucéat, M; Aberdam, D

    2012-02-01

    Since the discovery of the TP63 gene in 1998, many studies have demonstrated that ΔNp63, a p63 isoform of the p53 gene family, is involved in multiple functions during skin development and in adult stem/progenitor cell regulation. In contrast, TAp63 studies have been mostly restricted to its apoptotic function and more recently as the guardian of oocyte integrity. TAp63 endogenous expression is barely detectable in embryos and adult (except in oocytes), presumably because of its rapid degradation and the lack of antibodies able to detect weak expression. Nevertheless, two recent independent studies have demonstrated novel functions for TAp63 that could have potential implications to human pathologies. The first discovery is related to the protective role of TAp63 on premature aging. TAp63 controls skin homeostasis by maintaining dermal and epidermal progenitor/stem cell pool and protecting them from senescence, DNA damage and genomic instability. The second study is related to the role of TAp63, expressed by the primitive endoderm, on heart development. This unexpected role for TAp63 has been discovered by manipulation of embryonic stem cells in vitro and confirmed by the severe cardiomyopathy observed in brdm2 p63-null embryonic hearts. Interestingly, in both cases, TAp63 acts in a cell-nonautonomous manner on adjacent cells. Here, we discuss these findings and their potential connection during development. PMID:22158419

  5. Tapping the Sugar Maple--Learning and Appreciating

    ERIC Educational Resources Information Center

    Malone, Charles

    1976-01-01

    The article discusses how to tap a maple tree. Tapping a maple tree to produce maple syrup can: (1) lead to better understanding in many subject areas, (2) develop skills through participation in a rewarding activity, and (3) help students appreciate the many important roles that trees play in our environment and daily lives. (NQ)

  6. Healthy and Creative Tap Dance: Teaching a Lifetime Physical Activity

    ERIC Educational Resources Information Center

    Hernandez, Barbara L. Michiels; Ozmun, Michelle; Keeton, Gladys

    2013-01-01

    As a result of competitive dance television shows, interest in tap dance seems to have increased in the past few years. Tap dance is a challenging and fun lifetime physical activity that is appropriate for people of all ages. It is an excellent activity for K-12 physical education programs, higher education, parks and recreation facilities,…

  7. TAP High School Symposium: Lessons Learned from Principals and Teachers

    ERIC Educational Resources Information Center

    Barnett, Joshua H.

    2014-01-01

    Since the 1999-2000 school year, TAP: The System for Teacher and Student Advancement (TAP) has been implemented in hundreds of schools across the nation and demonstrated an ability to raise student achievement, improve the quality of instruction and increase the ability of high-need schools to recruit, retain and support effective teachers. The…

  8. A Dynamic Tap Allocation for Concurrent CMA-DD Equalizers

    NASA Astrophysics Data System (ADS)

    Trindade, Diego von B. M.; Halmenschlager, Vitor; Ortolan, Leonardo; De Castro, Maria C. F.; De Castro, Fernando C. C.; Ourique, Fabrício

    2010-12-01

    This paper proposes a dynamic tap allocation for the concurrent CMA-DD equalizer as a low complexity solution for the blind channel deconvolution problem. The number of taps is a crucial factor which affects the performance and the complexity of most adaptive equalizers. Generally an equalizer requires a large number of taps in order to cope with long delays in the channel multipath profile. Simulations show that the proposed new blind equalizer is able to solve the blind channel deconvolution problem with a specified and reduced number of active taps. As a result, it minimizes the output excess mean square error due to inactive taps during and after the equalizer convergence and the hardware complexity as well.

  9. Rational fabrication of a gold-coated AFM TERS tip by pulsed electrodeposition.

    PubMed

    Yang, Li-Kun; Huang, Teng-Xiang; Zeng, Zhi-Cong; Li, Mao-Hua; Wang, Xiang; Yang, Fang-Zu; Ren, Bin

    2015-11-21

    Reproducible fabrication of sharp gold- or silver-coated tips has become the bottleneck issue in tip-enhanced Raman spectroscopy, especially for atomic force microscopy (AFM)-based TERS. Herein, we developed a novel method based on pulsed electrodeposition to coat a thin gold layer over atomic force microscopy (AFM) tips to produce plasmonic TERS tips with high reproducibility. We systematically investigated the influence of the deposition potential and step time on the surface roughness and sharpness. This method allows the rational control of the radii of gold-coated TERS tips from a few to hundreds of nanometers, which allows us to systematically study the dependence of the TERS enhancement on the radius of the gold-coated AFM tip. The maximum TERS enhancement was achieved for the tip radius in the range of 60-75 nm in the gap mode. The coated gold layer has a strong adhesion with the silicon tip surface, which is highly stable in water, showing the great potential for application in the aqueous environment. PMID:26482226

  10. A low-cost AFM setup with an interferometer for undergraduates and secondary-school students

    NASA Astrophysics Data System (ADS)

    Bergmann, Antje; Feigl, Daniela; Kuhn, David; Schaupp, Manuel; Quast, Günter; Busch, Kurt; Eichner, Ludwig; Schumacher, Jens

    2013-07-01

    Atomic force microscopy (AFM) is an important tool in nanotechnology. This method makes it possible to observe nanoscopic surfaces beyond the resolution of light microscopy. In order to provide undergraduate and secondary-school students with insights into this world, we have developed a very robust low-cost AFM setup with a Fabry-Perot interferometer as a detecting device. This setup is designed to be operated almost completely manually and its simplicity gives access to a profound understanding of the working principle. Our AFM is operated in a constant height mode, i.e. the topography of the sample surface is represented directly by the deflection of the cantilever. Thus, the measuring procedure can be understood even by secondary-school students; furthermore, it is the method with the lowest cost, totalling not more than 10-15 k Euros. Nevertheless, we are able to examine a large variety of sample topographies such as CD and DVD surfaces, IC structures, blood cells, butterfly wings or moth eyes. Furthermore, force-distance curves can be recorded and the tensile moduli of some materials can be evaluated. We present our setup in detail and describe its working principles. In addition, we show various experiments which have already been performed by students.

  11. EEMD based pitch evaluation method for accurate grating measurement by AFM

    NASA Astrophysics Data System (ADS)

    Li, Changsheng; Yang, Shuming; Wang, Chenying; Jiang, Zhuangde

    2016-09-01

    The pitch measurement and AFM calibration precision are significantly influenced by the grating pitch evaluation method. This paper presents the ensemble empirical mode decomposition (EEMD) based pitch evaluation method to relieve the accuracy deterioration caused by high and low frequency components of scanning profile during pitch evaluation. The simulation analysis shows that the application of EEMD can improve the pitch accuracy of the FFT-FT algorithm. The pitch error is small when the iteration number of the FFT-FT algorithms was 8. The AFM measurement of the 500 nm-pitch one-dimensional grating shows that the EEMD based pitch evaluation method could improve the pitch precision, especially the grating line position precision, and greatly expand the applicability of the gravity center algorithm when particles and impression marks were distributed on the sample surface. The measurement indicates that the nonlinearity was stable, and the nonlinearity of x axis and forward scanning was much smaller than their counterpart. Finally, a detailed pitch measurement uncertainty evaluation model suitable for commercial AFMs was demonstrated and a pitch uncertainty in the sub-nanometer range was achieved. The pitch uncertainty was reduced about 10% by EEMD.

  12. Ultrasharp high-aspect-ratio probe array for SECM and AFM Analysis

    NASA Astrophysics Data System (ADS)

    Tao, Ye; Fasching, Rainer J.; Prinz, Fritz B.

    2004-07-01

    A powerful experimental tool, ultra-sharp nano-electrode array is designed, fabricated and characterized. The application on a combination of Scanning Electrochemical Microscopy (SECM) and the Atomic Force Microcopy (AFM) is demonstrated. It can measure sample electrochemically initiated by SECM changes of topography while detecting topography using AFM. In order to realize this, a specialized probe system that is composed of a micro-mechanical bending structure necessary for the AFM mode and an electrochemical UME-tip required for a high performance SECM is crucial. The probe array is a row of silicon transducers embedded in silicon nitride cantilever array. The sharp high-aspect ratio (20:1) silicon tips are shaped and a thin layer of silicon nitride is deposited, which embeds the silicon tips in a silicon nitride layer so that they protrude through the nitride. Thus, the embedded silicon tips with a diameter less than 600 nm, the top radius less than 20 nm, and the aspect ratio as high as 20 can be achieved. A metal layer and an insulator layer are deposited on these tip structures to make each probe selectively conductive. Finally, cantilever structures are shaped and released by etching the silicon substrate from the backside. Electrochemical and impedance spectroscopic characterization show electrochemical functionality of the transducer system.

  13. Rational fabrication of a gold-coated AFM TERS tip by pulsed electrodeposition

    NASA Astrophysics Data System (ADS)

    Yang, Li-Kun; Huang, Teng-Xiang; Zeng, Zhi-Cong; Li, Mao-Hua; Wang, Xiang; Yang, Fang-Zu; Ren, Bin

    2015-10-01

    Reproducible fabrication of sharp gold- or silver-coated tips has become the bottleneck issue in tip-enhanced Raman spectroscopy, especially for atomic force microscopy (AFM)-based TERS. Herein, we developed a novel method based on pulsed electrodeposition to coat a thin gold layer over atomic force microscopy (AFM) tips to produce plasmonic TERS tips with high reproducibility. We systematically investigated the influence of the deposition potential and step time on the surface roughness and sharpness. This method allows the rational control of the radii of gold-coated TERS tips from a few to hundreds of nanometers, which allows us to systematically study the dependence of the TERS enhancement on the radius of the gold-coated AFM tip. The maximum TERS enhancement was achieved for the tip radius in the range of 60-75 nm in the gap mode. The coated gold layer has a strong adhesion with the silicon tip surface, which is highly stable in water, showing the great potential for application in the aqueous environment.

  14. Ability of Lactobacillus rhamnosus GAF01 to remove AFM1 in vitro and to counteract AFM1 immunotoxicity in vivo.

    PubMed

    Abbès, Samir; Salah-Abbès, Jalila Ben; Sharafi, Hakimeh; Jebali, Rania; Noghabi, Kambiz Akbari; Oueslati, Ridha

    2013-01-01

    Aflatoxin M1 (AFM1) has been detected in many parts of the world both in raw milk and many dairy products, causing great economic losses and human disease. Unfortunately, there are few studies dealing with AFM1 immunotoxicity/interactions with lactic acid bacteria for potential application as a natural preventive agent. The aim of this study was to isolate (from dairy products) food-grade probiotic bacteria able to degrade/bind AFM1 in vitro and evaluate whether the same organism(s) could impart a protective role against AFM1-induced immunotoxicity in exposed Balb/c mice. Bacteria (Lactobacillus plantarum MON03 and L. rhamnosus GAF01) were isolated from Tunisian artisanal butter and then tested for abilities to eliminate AFM1 from phosphate-buffered saline (PBS) and reconstituted milk (containing 0.05, 0.10, and 0.20 µg AFM1/ml) after 0, 6, and 24 h at 37°C. Results showed that the selected bacteria could 'remove' AFM1 both in PBS and skimmed milk. The binding abilities of AFM1 by L. plantarum MON03 and L. rhamnosus GAF01 strains (at 10(8) CFU/ml) in PBS and reconstituted milk ranged, respectively, from 16.1-78.6% and 15.3-95.1%; overall, L. rhamnosus showed a better potential for removal than L. plantarum. 'Removal' appeared to be by simple binding; the bacteria/AFM1 complex was stable and only a very small proportion of mycotoxin was released back into the solution. L. rhamnosus GAF01 had the highest binding capacity and was selected for use in the in vivo study. Those results indicated that use of the organism prevented AFM1-induced effects on total white and red blood cells, and lymphocyte subtypes, after 15 days of host treatment. These studies clearly indicated that L. rhamnosus GAF01 was able to bind AFM1 in vitro and-by mechanisms that might also be related to a binding effect-counteract AFM1-induced immunotoxicity. Moreover, by itself, this bacterium was not toxic and could potentially be used as an additive in dairy products and in biotechnology for

  15. Atomic force microscopy combined with optical tweezers (AFM/OT)

    NASA Astrophysics Data System (ADS)

    Pierini, F.; Zembrzycki, K.; Nakielski, P.; Pawłowska, S.; Kowalewski, T. A.

    2016-02-01

    The role of mechanical properties is essential to understand molecular, biological materials, and nanostructures dynamics and interaction processes. Atomic force microscopy (AFM) is the most commonly used method of direct force evaluation, but due to its technical limitations this single probe technique is unable to detect forces with femtonewton resolution. In this paper we present the development of a combined atomic force microscopy and optical tweezers (AFM/OT) instrument. The focused laser beam, on which optical tweezers are based, provides us with the ability to manipulate small dielectric objects and to use it as a high spatial and temporal resolution displacement and force sensor in the same AFM scanning zone. We demonstrate the possibility to develop a combined instrument with high potential in nanomechanics, molecules manipulation and biological studies. AFM/OT equipment is described and characterized by studying the ability to trap dielectric objects and quantifying the detectable and applicable forces. Finally, optical tweezers calibration methods and instrument applications are given.

  16. In vitro evaluation of the loosening characteristics of self-tapped and non-self-tapped cortical bone screws.

    PubMed

    Vangsness, C T; Carter, D R; Frankel, V H

    1981-06-01

    The heads of self-tapping and non-self-tapping screws in dog femurs were exposed to a cyclic shearing force of 110 N for 200 loading cycles. This cyclic shear loading created a decrease in pull-out strength for both screw types of approximately 11% (p less than 0.01). No statistically significant difference in pull-out strength was found between screw types either before or after cyclic loading. A linear relationship between pull-out force and cortical thickness was observed for both screw types. These tests corroborated past work which showed equal holding power for the self-tapping and non-self-tapping screw. The progressive loosening of the screws with cyclic shear loading was accompanied by increasing load-displacement hysteresis and screw head migration. Greater hysteresis suggested that the non-self-tapping screw might have loosened more than the self-tapping screw from this applied loading schedule. Bone microcracking around screw threads before and after cyclic loading was observed by scanning electron microscopy. Photomicrographs of one non-self-tapping screw type and two self-tapping screw types showed microcracks at the tip of the outer diameter of the screw thread. More microcracks were observed after application of cyclic shear loading. PMID:7249457

  17. Nanoscale structural features determined by AFM for single virus particles.

    PubMed

    Chen, Shu-wen W; Odorico, Michael; Meillan, Matthieu; Vellutini, Luc; Teulon, Jean-Marie; Parot, Pierre; Bennetau, Bernard; Pellequer, Jean-Luc

    2013-11-21

    In this work, we propose "single-image analysis", as opposed to multi-image averaging, for extracting valuable information from AFM images of single bio-particles. This approach allows us to study molecular systems imaged by AFM under general circumstances without restrictions on their structural forms. As feature exhibition is a resolution correlation, we have performed AFM imaging on surfaces of tobacco mosaic virus (TMV) to demonstrate variations of structural patterns with probing resolution. Two AFM images were acquired with the same tip at different probing resolutions in terms of pixel width, i.e., 1.95 and 0.49 nm per pixel. For assessment, we have constructed an in silico topograph based on the three-dimensional crystal structure of TMV as a reference. The prominent artifacts observed in the AFM-determined shape of TMV were attributed to tip convolutions. The width of TMV rod was systematically overestimated by ~10 nm at both probing resolutions of AFM. Nevertheless, the effects of tip convolution were less severe in vertical orientation so that the estimated height of TMV by AFM imaging was in close agreement with the in silico X-ray topograph. Using dedicated image processing algorithms, we found that at low resolution (i.e., 1.95 nm per pixel), the extracted surface features of TMV can be interpreted as a partial or full helical repeat (three complete turns with ~7.0 nm in length), while individual protein subunits (~2.5 nm) were perceivable only at high resolution. The present study shows that the scales of revealed structural features in AFM images are subject to both probing resolution and processing algorithms for image analysis. PMID:24056758

  18. The Conductance of Nanotubes Deformed by the AFM Tip

    NASA Technical Reports Server (NTRS)

    Svizhenko, Alexei; Maiti, Amitesh; Anantram, M. P.

    2003-01-01

    The conductance drop under AFM-tip deformation can be explained by stretching of the tube length. NT sensors can be built utilizing uniform stretching. Single sp3 bond cross section cannot block electrons, because another conducting path may exist. AFM tip which forms sp3 bonds with the tube will decrease conductance. In the "table experiment" a conductance drop of 2 orders of magnitude happened only after some bonds were broken.

  19. Designer cantilevers for even more accurate quantitative measurements of biological systems with multifrequency AFM

    NASA Astrophysics Data System (ADS)

    Contera, S.

    2016-04-01

    Multifrequency excitation/monitoring of cantilevers has made it possible both to achieve fast, relatively simple, nanometre-resolution quantitative mapping of mechanical of biological systems in solution using atomic force microscopy (AFM), and single molecule resolution detection by nanomechanical biosensors. A recent paper by Penedo et al [2015 Nanotechnology 26 485706] has made a significant contribution by developing simple methods to improve the signal to noise ratio in liquid environments, by selectively enhancing cantilever modes, which will lead to even more accurate quantitative measurements.

  20. Performance evaluation of conventional and water saving taps.

    PubMed

    Fidar, A M; Memon, F A; Butler, D

    2016-01-15

    The rapid pace of urbanisation comes with considerable environmental implications including pressures on already stressed limited water resources. In urban areas, most of the water use is associated with water consumption in buildings. The second largest use of water is via taps. It is often assumed that water taps with low flow rates can contribute to reduced per capita water consumption. However, this is based on very little evidence. This paper presents the synthesis of a 13,000 high resolution observations made to investigate the actual water consumption of innovative (water saving) electronic taps and conventional mixer taps. High resolution flow-meters and data loggers were fitted into two washrooms in two different buildings of a higher education institution to record the water use through the basin taps. The recorded data provided information on duration, frequency of use and volume of water consumption per use. The data was helpful in identifying trends in hot and cold water use and therefore can be useful in estimating energy for producing hot water and associated greenhouse gas emissions. Analysis of the observed data suggests that the low flow taps have greater mean water consumption per event than the conventional taps and water consumption is more influenced by user behaviour rather than the technology. PMID:26437352

  1. TAP Report - Southwest Idaho Juniper Working Group

    SciTech Connect

    Gresham, Garold Linn

    2015-09-01

    There is explicit need for characterization of the materials for possible commercialization as little characterization data exists. Pinyon-juniper woodlands are a major ecosystem type found in the Southwest and the Intermountain West regions of the United States including Nevada, Idaho and Oregon. These widespread ecosystems are characterized by the presence of several different species of pinyon and juniper as the dominant plant cover. Since the 1800s, pinyon-juniper woodlands have rapidly expanded their range at the expense of existing ecosystems. Additionally, existing woodlands have become denser, progressively creating potential fire hazards as seen in the Soda Fire, which burned more than 400 sq. miles. Land managers responsible for these areas often desire to reduce pinyon-juniper coverage on their lands for a variety of reasons, as stated in the Working Group objectives. However, the cost of clearing thinning pinyon-juniper stands can be prohibitive. One reason for this is the lack of utilization options for the resulting biomass that could help recover some of the cost of pinyon-juniper stand management. The goal of this TAP effort was to assess the feedstock characteristics of biomass from a juniper harvested from Owyhee County to evaluate possible fuel and conversion utilization options.

  2. An advanced AFM sensor: its profile accuracy and low probe wear property for high aspect ratio patterns

    NASA Astrophysics Data System (ADS)

    Watanabe, Masahiro; Baba, Shuichi; Nakata, Toshihiko; Kurenuma, Toru; Kunitomo, Yuichi; Edamura, Manabu

    2007-03-01

    Design rule shrinkage and wider adoption of new device structures such as STI, copper damascene interconnects, and deep trench structures have made the need for in-line process monitoring of step heights and profiles of device structures more urgent. To monitor active device patterns, as opposed to test patterns as in OCD, AFM is the only non-destructive 3D monitoring tool. The barriers to using AFM in-line monitoring are its slow throughput and the accuracy degradation associated with probe tip wear and spike noise caused by unwanted oscillation on the steep slopes of high-aspect-ratio patterns. Our proprietary AFM scanning method, StepIn TM mode, is the method best suited to measuring high-aspect-ratio pattern profiles. Because the probe is not dragged on the sample surface as in conventional AFM, the profile trace fidelity across steep slopes is excellent. Because the probe does not oscillate and hit the sample at a high frequency, as in AC scanning mode, this mode is free from unwanted spurious noises on steep sample slopes and incurs extremely little probe tip wear. To take full advantage of the above properties, we have developed an AFM sensor that is optimized for in-line use and produces accurate profile data at high speeds and incurs little probe tip wear. The control scheme we have developed for the AFM sensor, which we call "Advanced StepIn TM", elaborately analyses the contact force signal, enabling efficient probe tip scanning and a low and stable contact force. With a developed AFM sensor that realizes this concept, we conducted an intensive evaluation on the effect of low and stable contact force scan. Probes with HDC (high density carbon) tips were used for the evaluation. The experiment proves that low contact force enhances the measured profile fidelity by preventing probe tip slip on steep slopes. Dynamics simulation of these phenomena was also conducted, and its results agreed well with the experimental results. The low contact force scan also

  3. Experimental discovery of a topological Weyl semimetal state in TaP.

    PubMed

    Xu, Su-Yang; Belopolski, Ilya; Sanchez, Daniel S; Zhang, Chenglong; Chang, Guoqing; Guo, Cheng; Bian, Guang; Yuan, Zhujun; Lu, Hong; Chang, Tay-Rong; Shibayev, Pavel P; Prokopovych, Mykhailo L; Alidoust, Nasser; Zheng, Hao; Lee, Chi-Cheng; Huang, Shin-Ming; Sankar, Raman; Chou, Fangcheng; Hsu, Chuang-Han; Jeng, Horng-Tay; Bansil, Arun; Neupert, Titus; Strocov, Vladimir N; Lin, Hsin; Jia, Shuang; Hasan, M Zahid

    2015-11-01

    Weyl semimetals are expected to open up new horizons in physics and materials science because they provide the first realization of Weyl fermions and exhibit protected Fermi arc surface states. However, they had been found to be extremely rare in nature. Recently, a family of compounds, consisting of tantalum arsenide, tantalum phosphide (TaP), niobium arsenide, and niobium phosphide, was predicted as a Weyl semimetal candidates. We experimentally realize a Weyl semimetal state in TaP. Using photoemission spectroscopy, we directly observe the Weyl fermion cones and nodes in the bulk, and the Fermi arcs on the surface. Moreover, we find that the surface states show an unexpectedly rich structure, including both topological Fermi arcs and several topologically trivial closed contours in the vicinity of the Weyl points, which provides a promising platform to study the interplay between topological and trivial surface states on a Weyl semimetal's surface. We directly demonstrate the bulk-boundary correspondence and establish the topologically nontrivial nature of the Weyl semimetal state in TaP, by resolving the net number of chiral edge modes on a closed path that encloses the Weyl node. This also provides, for the first time, an experimentally practical approach to demonstrating a bulk Weyl fermion from a surface state dispersion measured in photoemission. PMID:26702446

  4. Experimental discovery of a topological Weyl semimetal state in TaP

    PubMed Central

    Xu, Su-Yang; Belopolski, Ilya; Sanchez, Daniel S.; Zhang, Chenglong; Chang, Guoqing; Guo, Cheng; Bian, Guang; Yuan, Zhujun; Lu, Hong; Chang, Tay-Rong; Shibayev, Pavel P.; Prokopovych, Mykhailo L.; Alidoust, Nasser; Zheng, Hao; Lee, Chi-Cheng; Huang, Shin-Ming; Sankar, Raman; Chou, Fangcheng; Hsu, Chuang-Han; Jeng, Horng-Tay; Bansil, Arun; Neupert, Titus; Strocov, Vladimir N.; Lin, Hsin; Jia, Shuang; Hasan, M. Zahid

    2015-01-01

    Weyl semimetals are expected to open up new horizons in physics and materials science because they provide the first realization of Weyl fermions and exhibit protected Fermi arc surface states. However, they had been found to be extremely rare in nature. Recently, a family of compounds, consisting of tantalum arsenide, tantalum phosphide (TaP), niobium arsenide, and niobium phosphide, was predicted as a Weyl semimetal candidates. We experimentally realize a Weyl semimetal state in TaP. Using photoemission spectroscopy, we directly observe the Weyl fermion cones and nodes in the bulk, and the Fermi arcs on the surface. Moreover, we find that the surface states show an unexpectedly rich structure, including both topological Fermi arcs and several topologically trivial closed contours in the vicinity of the Weyl points, which provides a promising platform to study the interplay between topological and trivial surface states on a Weyl semimetal’s surface. We directly demonstrate the bulk-boundary correspondence and establish the topologically nontrivial nature of the Weyl semimetal state in TaP, by resolving the net number of chiral edge modes on a closed path that encloses the Weyl node. This also provides, for the first time, an experimentally practical approach to demonstrating a bulk Weyl fermion from a surface state dispersion measured in photoemission. PMID:26702446

  5. RegTAP - a New API to the VO Registry

    NASA Astrophysics Data System (ADS)

    Demleitner, M.

    2015-09-01

    The Virtual Observatory (VO) Registry is a comprehensive directory of astronomical services maintained collaboratively by major data centers across the globe. Until now, the API to the Registry as used by clients and users relied on several outdated standards, and has interoperability issues with more advanced queries. With RegTAP, there is now a relational schema exposed via the VO's Table Access Protocol as implemented by many clients, and several compliant services already exist. While many users will just use UIs operating RegTAP , both advanced users and client authors will want to directly operate the API. This paper provides an overview of RegTAP.

  6. TAp73 promotes anti-senescence-anabolism not proliferation

    PubMed Central

    Agostini, Massimiliano; Niklison-Chirou, Maria Victoria; Catani, Maria Valeria; Knight, Richard A.; Melino, Gerry; Rufini, Alessandro

    2014-01-01

    TAp73, a member of the p53 family, has been traditionally considered a tumor suppressor gene, but a recent report has claimed that it can promote cellular proliferation. This assumption is based on biochemical evidence of activation of anabolic metabolism, with enhanced pentose phosphate shunt (PPP) and nucleotide biosynthesis. Here, while we confirm that TAp73 expression enhances anabolism, we also substantiate its role in inhibiting proliferation and promoting cell death. Hence, we would like to propose an alternative interpretation of the accumulating data linking p73 to cellular metabolism: we suggest that TAp73 promotes anabolism to counteract cellular senescence rather than to support proliferation. PMID:25554796

  7. Development of a COLD TAPPING pipeline repair system

    SciTech Connect

    Quin, R.

    1985-01-01

    The COLD TAPPING technique provides a system that avoids flooding of a subsea pipeline during modifications, such as adding a connecting tee, or repair of the line. Pipeline pressure is equalised with the hydrostatic pressure of the seawater. A tap is performed on each side of the line to be modified. Plugs are inserted and inflated. Conventional hyperbaric welding is employed to effect the modifications or insertion of a new pipeline section. The plugs are removed by pigging and a clean line is restored without protrusions or weak points. Deep water trial have shown that the COLD TAPPING operation can be accomplished in under two days.

  8. Parametric effects in nanobeams and AFM

    SciTech Connect

    Claeyssen, J. C. R.; Tonetto, L.; Carvalho, J. B.; Copetti, R. D.

    2014-12-10

    Vibration dynamics of forced cantilever beams that are used in nanotechnology such as atomic force microscope modeling and carbon nanotubes is considered in terms of a fundamental response within a matrix framework. The modeling equations are written as a matrix differential equation subject to tip-sample general boundary conditions. At the junctions, where there are discontinuities due to different material or beam thickness, compatibility conditions are prescribed. Forced responses are given by convolution of the input load with the time domain Green matrix function. The corresponding matrix transfer function and modes of a multispan cantilever beam are determined in terms of solution basis of the same shape generated by a fundamental solution. Simulations were performed for a three stepped beam with a piezoelectric patch subject to pulse forcing terms and with surface effects.

  9. Parametric effects in nanobeams and AFM

    NASA Astrophysics Data System (ADS)

    Claeyssen, J. C. R.; Tonetto, L.; Carvalho, J. B.; Copetti, R. D.

    2014-12-01

    Vibration dynamics of forced cantilever beams that are used in nanotechnology such as atomic force microscope modeling and carbon nanotubes is considered in terms of a fundamental response within a matrix framework. The modeling equations are written as a matrix differential equation subject to tip-sample general boundary conditions. At the junctions, where there are discontinuities due to different material or beam thickness, compatibility conditions are prescribed. Forced responses are given by convolution of the input load with the time domain Green matrix function. The corresponding matrix transfer function and modes of a multispan cantilever beam are determined in terms of solution basis of the same shape generated by a fundamental solution. Simulations were performed for a three stepped beam with a piezoelectric patch subject to pulse forcing terms and with surface effects.

  10. Changes in collagen fibril pattern and adhesion force with collagenase-induced injury in rat Achilles tendon observed via AFM.

    PubMed

    Lee, Gi-Ja; Choi, Samjin; Chon, Jinmann; Yoo, Seungdon; Cho, Ilsung; Park, Hun-Kuk

    2011-01-01

    The Achilles tendon consists mainly of type I collagen fibers that contain collagen fibrils. When the Achilles tendon is injured, it is inflamed. The collagenase-induced model has been widely used to study tendinitis. The major advantages of atomic force microscopy (AFM) over conventional optical and electron microscopy for bio-imaging include its non-requirement of a special coating and vacuum, and its capability to perform imaging in all environments. AFM force-distance measurements have become a fundamental tool in the fields of surface chemistry, biochemistry and materials science. Therefore, the changes in the ultrastructure and adhesion force of the collagen fibrils on the Achilles tendons of rats with Achilles tendinitis were observed using AFM. The changes in the structure of the Achilles tendons were evaluated based on the diameter and D-banding of the collagen fibrils. Collagenase-induced Achilles tendinitis was induced with the injection of 30 microl crude collagenase into 7-week-old male Sprague-Dawley rats. The animals were each sacrificed on the first, second, third, fifth and seventh day after the collagenase injection. The normal and injured Achilles tendons were fixed in 4% buffered formalin and dehydrated with increasing concentrations of ethanol. AFM was performed using the non-contact mode at the resolution of 512 x 512 pixels, with a scan speed of 0.8 line/sec. The adhesion force was measured via the force-distance curve that resulted from the interactions between the AFM tip and the collagen fibril sample using the contact mode. The diameter of the collagen fibrils in the Achilles tendons significantly decreased (p < 0.05) after the collagenase injection, and the pattern of the D-banding of the collagen fibrils was similar to that of the diameter changes. The adhesion force decreased until the fifth day after the collagenase injection, but increased on the seventh day after the collagenase injection (p < 0.0001). PMID:21446543

  11. Beer tapping: dynamics of bubbles after impact

    NASA Astrophysics Data System (ADS)

    Mantič-Lugo, V.; Cayron, A.; Brun, P.-T.; Gallaire, F.

    2015-12-01

    Beer tapping is a well known prank where a bottle of beer is impacted from the top by a solid object, usually another bottle, leading to a sudden foam overflow. A description of the shock-driven bubble dynamics leading to foaming is presented based on an experimental and numerical study evoking the following physical picture. First, the solid impact produces a sudden downwards acceleration of the bottle creating a strong depression in the liquid bulk. The existing bubbles undergo a strong expansion and a sudden contraction ending in their collapse and fragmentation into a large amount of small bubbles. Second, the bubble clouds present a large surface area to volume ratio, enhancing the CO2 diffusion from the supersaturated liquid, hence growing rapidly and depleting the CO2. The clouds of bubbles migrate upwards in the form of plumes pulling the surrounding liquid with them and eventually resulting in the foam overflow. The sudden pressure drop that triggers the bubble dynamics with a collapse and oscillations is modelled by the Rayleigh-Plesset equation. The bubble dynamics from impact to collapse occurs over a time (tb ≃ 800 μs) much larger than the acoustic time scale of the liquid bulk (tac = 2H/c ≃ 80 μs), for the experimental container of height H = 6 cm and a speed of sound around c ≃ 1500 m/s. This scale separation, together with the comparison of numerical and experimental results, suggests that the pressure drop is controlled by two parameters: the acceleration of the container and the distance from the bubble to the free surface.

  12. Pre-tapped and self-tapping screws in children's mandibles. A scanning electron microscopic examination of the implant beds.

    PubMed

    Bähr, W; Stoll, P

    1991-10-01

    One hundred 2 mm AO miniscrews were inserted into the mandibles of eight fresh cadavers aged 8 to 12 years. Scanning electron microscopic examination of the implant beds showed cracks and accumulated bone material, as well as signs of crushing and shearing stress, regardless of whether the screws were pre-tapped or not. When, during screw insertion, the axis of the screw deviated by at least 10 degrees from the axis of the tap, two intersecting threads resulted. It is concluded that during osteosynthesis in child mandibles pre-tapping is not recommended. PMID:1742264

  13. VIEW FACING EAST LOOKING DOWN FROM OPEN HEARTH TAPPING FLOOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW FACING EAST LOOKING DOWN FROM OPEN HEARTH TAPPING FLOOR AREA, NOTE FOUNDATIONS OF OPEN HEARTH FURNACES. - Pittsburgh Steel Company, Monessen Works, Open Hearth Plant, Donner Avenue, Monessen, Westmoreland County, PA

  14. 'Hard' Tap Water Linked to Eczema in Babies

    MedlinePlus

    ... gov/medlineplus/news/fullstory_159150.html 'Hard' Tap Water Linked to Eczema in Babies Skin condition seems ... likely in areas with high mineral content in water, study finds To use the sharing features on ...

  15. 'Hard' Tap Water Linked to Eczema in Babies

    MedlinePlus

    ... medlineplus.gov/news/fullstory_159150.html 'Hard' Tap Water Linked to Eczema in Babies Skin condition seems ... likely in areas with high mineral content in water, study finds To use the sharing features on ...

  16. Novel Brain Cancer Treatment Taps into Sound Waves

    MedlinePlus

    ... nih.gov/medlineplus/news/fullstory_159386.html Novel Brain Cancer Treatment Taps Into Sound Waves Experimental device ... 15, 2016 WEDNESDAY, June 15, 2016 (HealthDay News) -- Brain cancer patients might benefit from an implantable ultrasound ...

  17. Water resources along the TAPS route, Alaska, 1970-74

    USGS Publications Warehouse

    Childers, Joseph M.; Nauman, J.W.; Kernodle, D.R.; Doyle, P.F.

    1978-01-01

    The U.S. Geological Survey installed 10 streamgaging and water-quality stations along the trans-Alaska pipeline route (TAPS) starting in 1970. These stations, mostly north of Fairbanks, add to the historical network of gaging stations and provide records of hydrologic conditions along the TAPS route. Selected data from 23 gaging stations along the TAPS route for the period 1970-74 (prior to construction of the pipeline) are compiled in graphic form. The data include annual hydrographs of daily mean or instantaneous values of a standard set of parameters which are indicative of physical, chemical and biological conditions of the streams. The hydrographs facilitate comparisons of data, both in time and between stream sites. Thus , they are a tool for evaluating streamflow characteristics along the TAPS route during the preconstruction period. (Woodard-USGS)

  18. Astronomy on Tap: science engagement in the pub

    NASA Astrophysics Data System (ADS)

    Livermore, Rachael C.; Silverman, Jeffrey Michael

    2015-08-01

    Astronomy on Tap is a series of free lectures by astronomers in the pub, aimed at disseminating the latest research to the public in an informal setting. Started in New York City in 2013, Astronomy on Tap has now expanded to seven cities across North and South America. Organized by local astronomers, each event features talks by astronomers from local institutions or visitors, or others whose professions or hobbies intersect with astronomy, along with games and opportunities for the public to interact with professional astronomers. The largest Astronomy on Tap events are in Austin, Texas, attracting over 150 people each month, which consists of populations outside of the self-selected groups that might be reached by more formal EPO activities. The organisers of Astronomy on Tap in Austin (AoTATX) will discuss the impact of and feedback from all of the locations, and present information on setting up new satellite locations.

  19. Global Team Taps into DNA Behind Type 2 Diabetes

    MedlinePlus

    ... news/fullstory_159810.html Global Team Taps Into DNA Behind Type 2 Diabetes Many common gene variations ... the researchers assessed the influence of rare, "private" DNA differences along with common DNA differences that many ...

  20. In-Situ AFM Investigation of Solid Electrolyte Interphase Formation and Failure Mechanisms in Lithium -Ion Batteries

    NASA Astrophysics Data System (ADS)

    Mueller, Thomas; Kumar, Ravi; Tokranov, Anton; Huang, Teddy; Li, Chunzeng; Xiao, Xingcheng; Sheldon, Brian

    The formation and evolution of the solid electrolyte interphase (SEI) is critical for lifetime and performance of lithium-ion batteries (LIBs), particularly for LIBs with high energy density materials such as silicon. Si has almost ten time theoretical specific capacity vs graphite, but its volume changes during cycling (up to 400%) put enormous strains on the SEI layer, resulting in continuous capacity loss. In this study we report in situ atomic force microscopy (AFM) investigation on the formation and failure mechanisms of SEI layer using patterned Si island structures. Due to the shear lag effect, patterned Si islands go through lateral expansion and Contraction, putting the SEI layer in tension and compression during lithiation and delithiation, respectively. Experimentally, we performed the studies in a glovebox with <1 ppm O2 and H2O, using PeakForce Tapping to image the extremely fragile SEI layer. We show for the first time the in operando cracking of SEI layer. To understand the mechanics of the SEI layer, the critical strain for cracking was derived from a progression of the AFM images. Our studies provide new insight into SEI formation, evolution and its mechanical response, and offer guidance to tailor passivation layers for optimal performance.

  1. A Posterior TAP Block Provides More Effective Analgesia Than a Lateral TAP Block in Patients Undergoing Laparoscopic Gynecologic Surgery: A Retrospective Study

    PubMed Central

    Yoshiyama, Sakatoshi; Ueshima, Hironobu; Sakai, Ryomi; Otake, Hiroshi

    2016-01-01

    Background. There are a few papers that compared the lateral transversus abdominis plane (TAP) block with the posterior TAP block. Our study aimed to compare retrospectively the quality of analgesia after laparoscopic gynecologic surgery using the lateral TAP block with general anesthesia versus the posterior TAP block with general anesthesia. Method. Sixty-seven adult female patients were included in this retrospective study. Of these patients, thirty-four patients received the lateral TAP block with general anesthesia (lat. TAP group), and the rest of thirty-three patients received the posterior TAP block with general anesthesia (pos. TAP group). Pain scores both at rest and at movement and the use of additional analgesic drugs were recorded in the postoperative care unit within twenty-four hours after the operation. Postoperative complications were noted. Results. Patients who received pos. TAP reported lower visual analog scale (VAS) pain scores in all points, within twenty-four hours after the operation, than patients who received lat. TAP. Moreover, with the use of additional analgesic drugs, the incidence of nausea and vomiting during the first twenty-four hours after surgery was lower in the pos. TAP group than in the lat. TAP group. Conclusion. The posterior TAP block provided more effective analgesia than the lateral TAP block in patients undergoing laparoscopic gynecologic surgery. PMID:26941794

  2. AFM investigation of Martian soil simulants on micromachined Si substrates.

    PubMed

    Vijendran, S; Sykulska, H; Pike, W T

    2007-09-01

    The micro and nanostructures of Martian soil simulants with particles in the micrometre-size range have been studied using a combination of optical and atomic force microscopy (AFM) in preparation for the 2007 NASA Phoenix Mars Lander mission. The operation of an atomic force microscope on samples of micrometre-sized soil particles is a poorly investigated area where the unwanted interaction between the scanning tip and loose particles results in poor image quality and tip contamination by the sample. In order to mitigate these effects, etched silicon substrates with a variety of features have been used to facilitate the sorting and gripping of particles. From these experiments, a number of patterns were identified that were particularly good at isolating and immobilizing particles for AFM imaging. This data was used to guide the design of micromachined substrates for the Phoenix AFM. Both individual particles as well as aggregates were successfully imaged, and information on sizes, shapes and surface morphologies were obtained. This study highlights both the strengths and weaknesses of AFM for the potential in situ investigation of Martian soil and dust. Also presented are more general findings of the limiting operational constraints that exist when attempting the AFM of high aspect ratio particles with current technology. The performance of the final designs of the substrates incorporated on Phoenix will be described in a later paper. PMID:17760618

  3. Tapping lakes in Norway: clean but risky energy

    SciTech Connect

    Not Available

    1986-12-01

    Four hydroelectric projects are currently underway and two more are expected to begin within the next couple of years in Norway, using lake taps. The Ulla-Forre project is presently under construction which uses lake taps to link 30 lakes and many rivers through a network of tunnels and dams. Environmentalists are concerned that dams and other above-ground components of these projects will interfere with the migration routes of reindeer and spawning salmon.

  4. TAP - Tools for Adaptive Partitioning v. 0.99 Beta

    2008-11-19

    TAP is a set of tools which are essential for conducting research on adaptive partitioners. The basic premise is that a single partitioner may not be a good choice for adaptive mesh simulations; rather one must match a partitioner (obtained from a partitioning package like Zoltan, ParMetis etc) with the mesh being partitioned. TAP provides the tools that can judge the suitability of a partitioning algorithm to a given mesh.

  5. Lessons from the TAPS study-knowledge and skills errors.

    PubMed

    Makeham, Meredith A B; Mira, Michael; Kidd, Michael R

    2008-03-01

    The Threats to Australian Patient Safety (TAPS) Study collected 648 anonymous reports about threats to patient safety from a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened and would not want to happen again, regardless of who was at fault or the outcome of the event. This series of articles presents clinical lessons resulting from the TAPS study. PMID:18345364

  6. Lessons from the TAPS study - message handling and appointment systems.

    PubMed

    Makeham, Meredith A B; Cooper, Chris; Kidd, Michael R

    2008-06-01

    The Threats to Australian Patient Safety (TAPS) Study collected 648 anonymous reports about threats to patient safety from a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened, and would not want to happen again, regardless of who was at fault or the outcome of the event. This series of articles presents clinical lessons resulting from the TAPS study. PMID:18523697

  7. Lessons from the TAPS study--recall and reminder systems.

    PubMed

    Makeham, Meredith A B; Saltman, Deborah C; Kidd, Michael R

    2008-11-01

    The Threats to Australian Patient Safety (TAPS) study collected 648 anonymous reports about threats to patient safety from a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened and would not want to happen again, regardless of who was at fault or the outcome of the event. THis series of articles presents clinical lessons resulting from the TAPS study. PMID:19037466

  8. Lessons from the TAPS study - management of medical emergencies.

    PubMed

    Makeham, Meredith A B; Saltman, Deborah C; Kidd, Michael R

    2008-07-01

    The Threats to Australian Patient Safety (TAPS) study collected 648 anonymous reports about threats to patient safety by a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened, and would not want to happen again, regardless of who was at fault or the outcome of the event. This series of articles presents clinical lessons resulting from the TAPS study. PMID:18592074

  9. Lessons from the TAPS study - errors relating to medical records.

    PubMed

    Makeham, Meredith A B; Bridges-Webb, Charles; Kidd, Michael R

    2008-04-01

    The Threats to Australian Patient Safety (TAPS) Study collected 648 anonymous reports about threats to patient safety from a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened and would not want to happen again, regardless of who was at fault or the outcome of the event. This series of articles presents clinical lessons resulting from the TAPS study. PMID:18398521

  10. Comparative Raman study of Weyl semimetals TaAs, NbAs, TaP and NbP.

    PubMed

    Liu, H W; Richard, P; Zhao, L X; Chen, G-F; Ding, H

    2016-07-27

    We report a comparative polarized Raman study of Weyl semimetals TaAs, NbAs, TaP and NbP. The evolution of the phonon frequencies with the sample composition allows us to determine experimentally which atoms are mainly involved for each vibration mode. Our results confirm previous first-principles calculations indicating that the A1, B1(2), E(2) and E(3) modes involve mainly the As(P) atoms, the B1(1) mode is mainly related to Ta(Nb) atoms, and the E(1) mode involves both kinds of atoms. By comparing the energy of the different modes, we establish that the B1(1), B1(2), E(2) and E(3) become harder with increasing chemical pressure. This behaviour differs from our observation on the A1 mode, which decreases in energy, in contrast to its behaviour under external pressure. PMID:27248581

  11. Comparative Raman study of Weyl semimetals TaAs, NbAs, TaP and NbP

    NASA Astrophysics Data System (ADS)

    Liu, H. W.; Richard, P.; Zhao, L. X.; Chen, G.-F.; Ding, H.

    2016-07-01

    We report a comparative polarized Raman study of Weyl semimetals TaAs, NbAs, TaP and NbP. The evolution of the phonon frequencies with the sample composition allows us to determine experimentally which atoms are mainly involved for each vibration mode. Our results confirm previous first-principles calculations indicating that the A1, B1(2), E(2) and E(3) modes involve mainly the As(P) atoms, the B1(1) mode is mainly related to Ta(Nb) atoms, and the E(1) mode involves both kinds of atoms. By comparing the energy of the different modes, we establish that the B1(1), B1(2), E(2) and E(3) become harder with increasing chemical pressure. This behaviour differs from our observation on the A1 mode, which decreases in energy, in contrast to its behaviour under external pressure.

  12. Charging C60 islands with the AFM tip.

    PubMed

    Hoff, Brice; Henry, Claude R; Barth, Clemens

    2016-01-01

    We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system. PMID:26617348

  13. Liquid contact resonance AFM: analytical models, experiments, and limitations

    NASA Astrophysics Data System (ADS)

    Parlak, Zehra; Tu, Qing; Zauscher, Stefan

    2014-11-01

    Contact resonance AFM (CR-AFM) is a scanning probe microscopy technique that utilizes the contact resonances of the AFM cantilever for concurrent imaging of topography and surface stiffness. The technique has not been used in liquid until recently due to analytical and experimental difficulties, associated with viscous damping of cantilever vibrations and fluid loading effects. To address these difficulties, (i) an analytical approach for contact resonances in liquid is developed, and (ii) direct excitation of the contact resonances is demonstrated by actuating the cantilever directly in a magnetic field. By implementing the analytical approach and the direct actuation through magnetic particles, quantitative stiffness imaging on surfaces with a wide range of stiffness can be achieved in liquid with soft cantilevers and low contact forces.

  14. AFM of biological complexes: what can we learn?

    PubMed Central

    Gaczynska, Maria; Osmulski, Pawel A.

    2009-01-01

    The term “biological complexes” broadly encompasses particles as diverse as multisubunit enzymes, viral capsids, transport cages, molecular nets, ribosomes, nucleosomes, biological membrane components and amyloids. The complexes represent a broad range of stability and composition. Atomic force microscopy offers a wealth of structural and functional data about such assemblies. For this review, we choose to comment on the significance of AFM to study various aspects of biology of selected nonmembrane protein assemblies. Such particles are large enough to reveal many structural details under the AFM probe. Importantly, the specific advantages of the method allow for gathering dynamic information about their formation, stability or allosteric structural changes critical for their function. Some of them have already found their way to nanomedical or nanotechnological applications. Here we present examples of studies where the AFM provided pioneering information about the biology of complexes, and examples of studies where the simplicity of the method is used toward the development of potential diagnostic applications. PMID:19802337

  15. Improvement in metrology on new 3D-AFM platform

    NASA Astrophysics Data System (ADS)

    Schmitz, Ingo; Osborn, Marc; Hand, Sean; Chen, Qi

    2008-10-01

    According to the 2007 edition of the ITRS roadmap, the requirement for CD uniformity of isolated lines on a binary or attenuated phase shift mask is 2.1nm (3σ) in 2008 and requires improvement to1.3 nm (3σ) in 2010. In order to meet the increasing demand for CD uniformity on photo masks, improved CD metrology is required. A next generation AFM, InSightTM 3DAFM, has been developed to meet these increased requirements for advanced photo mask metrology. The new system achieves 2X improvement in CD and depth precision on advanced photo masks features over the previous generation 3D-AFM. This paper provides measurement data including depth, CD, and sidewall angle metrology. In addition the unique capabilities of damage-free defect inspection and Nanoimprint characterization by 3D AFM are presented.

  16. Mounting of Escherichia coli spheroplasts for AFM imaging.

    SciTech Connect

    Sullivan, Claretta J; Morrell-Falvey, Jennifer L; Allison, David P; Doktycz, Mitchel John

    2005-11-01

    The cytoplasmic membrane of Escherichia coli (E. coli) is the location of numerous, chemically specific transporters and recognition elements. Investigation of this membrane in vivo by atomic force microscopy (AFM) requires removal of the cell wall and stable immobilization of the spheroplast. AFM images demonstrate that spheroplasts can be secured with warm gelatin applied to the mica substrate just before the addition of a spheroplast suspension. The resulting preparation can be repeatedly imaged by AFM over the course of several hours. Confocal fluorescence imaging confirms the association of the spheroplasts with the gelatin layer. Gelatin molecules are known to reorder into a network after heating. Entrapment within this gelatin network is believed to be responsible for the immobilization of spheroplasts on mica.

  17. Surface Morphological Studies on Nerve Cells by AFM

    NASA Astrophysics Data System (ADS)

    Durkaya, Goksel; Zhong, Lei; Rehder, Vincent; Dietz, Nikolaus

    2009-03-01

    Surface morphological properties of fixed and living nerve cells removed from the buccal ganglion of Helisoma trivolvis have been studied by using Atomic Force Microscopy (AFM). Identified, individual neurons were removed from the buccal ganglion of Helisoma trivolvis and plated into poly-L-lysine coated glass cover-slips. The growth of the nerve cells was stopped and fixed with 0.1% Glutaraldehyde and 4% Formaldehyde solution after extension of growth cones at the tip of the axons. Topography and softness of growth cone filopodia and overlying lamellopodium (veil) were probed by AFM. Information obtained from AFM's amplitude and phase channels have been used for determination of softness of the region probed. The results of structural studies on the cells are linked to their mechanical properties and internal molecular density distribution.

  18. Charging C60 islands with the AFM tip

    NASA Astrophysics Data System (ADS)

    Hoff, Brice; Henry, Claude R.; Barth, Clemens

    2015-12-01

    We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system.We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR04541J

  19. BOREAS AFM-04 Twin Otter Aircraft Flux Data

    NASA Technical Reports Server (NTRS)

    MacPherson, J. Ian; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Desjardins, Raymond L.; Smith, David E. (Technical Monitor)

    2000-01-01

    The BOREAS AFM-5 team collected and processed data from the numerous radiosonde flights during the project. The goals of the AFM-05 team were to provide large-scale definition of the atmosphere by supplementing the existing AES aerological network, both temporally and spatially. This data set includes basic upper-air parameters collected from the network of upper-air stations during the 1993, 1994, and 1996 field campaigns over the entire study region. The data are contained in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884) or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  20. GPIM AF-M315E Propulsion System

    NASA Technical Reports Server (NTRS)

    Spores, Ronald A.; Masse, Robert; Kimbrel, Scott; McLean, Chris

    2014-01-01

    The NASA Space Technology mission Directorate's (STMD) Green Propellant Infusion Mission (GPIM) Technology Demonstration Mission (TDM) will demonstrate an operational AF-M315E green propellant propulsion system. Aerojet-Rocketdyne is responsible for the development of the propulsion system payload. This paper statuses the propulsion system module development, including thruster design and system design; Initial test results for the 1N engineering model thruster are presented. The culmination of this program will be high-performance, green AF-M315E propulsion system technology at TRL 7+, with components demonstrated to TRL 9, ready for direct infusion to a wide range of applications for the space user community.

  1. Learning about Modes in Atomic Force Microscopy by Means of Hands-On Activities Based on a Simple Apparatus

    ERIC Educational Resources Information Center

    Phuapaiboon, Unchada; Panijpan, Bhinyo; Osotchan, Tanakorn

    2009-01-01

    This study was conducted to examine the results of using a low-cost hands-on setup in combination with accompanying activities to promote understanding of the contact mode of atomic force microscopy (AFM). This contact mode setup enabled learners to study how AFM works by hand scanning using probing cantilevers with different characteristics on…

  2. Chicken TAP genes differ from their human orthologues in locus organisation, size, sequence features and polymorphism.

    PubMed

    Walker, Brian A; van Hateren, Andrew; Milne, Sarah; Beck, Stephan; Kaufman, Jim

    2005-05-01

    We have previously shown that in the chicken major histocompatibility complex, the two transporters associated with antigen processing genes (TAP1 and TAP2) are located head to head between two classical class I genes. Here we show that the region between these two TAP genes has transcription factor-binding sites in common with class I gene promoters. The TAP genes are also up-regulated by interferon-gamma in a similar way to mammalian TAP genes and in a way that suggests they are both transcribed from a bi-directional promoter. The gene structures of TAP1 and TAP2 differ from that of human TAPs in that TAP1 has a truncated exon 1 and TAP2 has fused exons, resulting in a much smaller gene size. The truncation of TAP1 results in the loss of approximately 150 amino acids, which are thought to be involved in endoplasmic reticulum retention, heterodimer formation and tapasin binding, compared to human TAP1. Most of the protein sequence features involved in binding ATP are conserved, with two exceptions: chicken TAP1 has a glycine in the switch region where other TAPs have glutamine or histidine, and both chicken TAP genes have serines in the C motif where mammalian TAP2 has an alanine. Lastly, the chicken TAP genes are highly polymorphic, with at least as many TAP alleles as there are class I alleles, as seen by investigating nine inbred lines of chicken. The close proximity of the TAP genes to the class I genes and the high level of polymorphism may allow co-evolution of the genes, allowing TAP molecules to transport peptides specifically for the class I molecules of that haplotype. PMID:15900495

  3. AFM CHARACTERIZATION OF LASER INDUCED DAMAGE ON CDZNTE CRYSTAL SURFACES

    SciTech Connect

    Hawkins, S; Lucile Teague, L; Martine Duff, M; Eliel Villa-Aleman, E

    2008-06-10

    Semi-conducting CdZnTe (or CZT) crystals can be used in a variety of detector-type applications. CZT shows great promise for use as a gamma radiation spectrometer. However, its performance is adversely affected by point defects, structural and compositional heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), secondary phases and in some cases, damage caused by external forces. One example is damage that occurs during characterization of the surface by a laser during Raman spectroscopy. Even minimal laser power can cause Te enriched areas on the surface to appear. The Raman spectra resulting from measurements at moderate intensity laser power show large increases in peak intensity that is attributed to Te. Atomic Force Microscopy (AFM) was used to characterize the extent of damage to the CZT crystal surface following exposure to the Raman laser. AFM data reveal localized surface damage in the areas exposed to the Raman laser beam. The degree of surface damage to the crystal is dependent on the laser power, with the most observable damage occurring at high laser power. Moreover, intensity increases in the Te peaks of the Raman spectra are observed even at low laser power with little to no visible damage observed by AFM. AFM results also suggest that exposure to the same amount of laser power yields different amounts of surface damage depending on whether the exposed surface is the Te terminating face or the Cd terminating face of CZT.

  4. 3D Color Digital Elevation Map of AFM Sample

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This color image is a three dimensional (3D) view of a digital elevation map of a sample collected by NASA's Phoenix Mars Lander's Atomic Force Microscope (AFM).

    The image shows four round pits, only 5 microns in depth, that were micromachined into the silicon substrate, which is the background plane shown in red. This image has been processed to reflect the levelness of the substrate.

    A Martian particle only one micrometer, or one millionth of a meter, across is held in the upper left pit.

    The rounded particle shown at the highest magnification ever seen from another world is a particle of the dust that cloaks Mars. Such dust particles color the Martian sky pink, feed storms that regularly envelop the planet and produce Mars' distinctive red soil.

    The particle was part of a sample informally called 'Sorceress' delivered to the AFM on the 38th Martian day, or sol, of the mission (July 2, 2008). The AFM is part of Phoenix's microscopic station called MECA, or the Microscopy, Electrochemistry, and Conductivity Analyzer.

    The AFM was developed by a Swiss-led consortium, with Imperial College London producing the silicon substrate that holds sampled particles.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  5. Structural investigations on native collagen type I fibrils using AFM

    SciTech Connect

    Strasser, Stefan; Zink, Albert; Janko, Marek; Heckl, Wolfgang M.; Thalhammer, Stefan . E-mail: stefan.thalhammer@gsf.de

    2007-03-02

    This study was carried out to determine the elastic properties of single collagen type I fibrils with the use of atomic force microscopy (AFM). Native collagen fibrils were formed by self-assembly in vitro characterized with the AFM. To confirm the inner assembly of the collagen fibrils, the AFM was used as a microdissection tool. Native collagen type I fibrils were dissected and the inner core uncovered. To determine the elastic properties of collagen fibrils the tip of the AFM was used as a nanoindentor by recording force-displacement curves. Measurements were done on the outer shell and in the core of the fibril. The structural investigations revealed the banding of the shell also in the core of native collagen fibrils. Nanoindentation experiments showed the same Young's modulus on the shell as well as in the core of the investigated native collagen fibrils. In addition, the measurements indicate a higher adhesion in the core of the collagen fibrils compared to the shell.

  6. Introduction to Atomic Force Microscopy (AFM) in Biology.

    PubMed

    Kreplak, Laurent

    2016-01-01

    The atomic force microscope (AFM) has the unique capability of imaging biological samples with molecular resolution in buffer solution over a wide range of time scales from milliseconds to hours. In addition to providing topographical images of surfaces with nanometer- to angstrom-scale resolution, forces between single molecules and mechanical properties of biological samples can be investigated from the nano-scale to the micro-scale. Importantly, the measurements are made in buffer solutions, allowing biological samples to "stay alive" within a physiological-like environment while temporal changes in structure are measured-e.g., before and after addition of chemical reagents. These qualities distinguish AFM from conventional imaging techniques of comparable resolution, e.g., electron microscopy (EM). This unit provides an introduction to AFM on biological systems and describes specific examples of AFM on proteins, cells, and tissues. The physical principles of the technique and methodological aspects of its practical use and applications are also described. © 2016 by John Wiley & Sons, Inc. PMID:27479503

  7. Hydrodynamic effects in fast AFM single-molecule force measurements.

    PubMed

    Janovjak, Harald; Struckmeier, Jens; Müller, Daniel J

    2005-02-01

    Atomic force microscopy (AFM) allows the critical forces that unfold single proteins and rupture individual receptor-ligand bonds to be measured. To derive the shape of the energy landscape, the dynamic strength of the system is probed at different force loading rates. This is usually achieved by varying the pulling speed between a few nm/s and a few microm/s, although for a more complete investigation of the kinetic properties higher speeds are desirable. Above 10 microm/s, the hydrodynamic drag force acting on the AFM cantilever reaches the same order of magnitude as the molecular forces. This has limited the maximum pulling speed in AFM single-molecule force spectroscopy experiments. Here, we present an approach for considering these hydrodynamic effects, thereby allowing a correct evaluation of AFM force measurements recorded over an extended range of pulling speeds (and thus loading rates). To support and illustrate our theoretical considerations, we experimentally evaluated the mechanical unfolding of a multi-domain protein recorded at 30 microm/s pulling speed. PMID:15257425

  8. AFM Structural Characterization of Drinking Water Biofilm under Physiological Conditions

    EPA Science Inventory

    Due to the complexity of mixed culture drinking water biofilm, direct visual observation under in situ conditions has been challenging. In this study, atomic force microscopy (AFM) revealed the three dimensional morphology and arrangement of drinking water relevant biofilm in air...

  9. Quantum amplification and quantum optical tapping with squeezed states and correlated quantum states

    NASA Technical Reports Server (NTRS)

    Ou, Z. Y.; Pereira, S. F.; Kimble, H. J.

    1994-01-01

    Quantum fluctuations in a nondegenerate optical parametric amplifier (NOPA) are investigated experimentally with a squeezed state coupled into the internal idler mode of the NOPA. Reductions of the inherent quantum noise of the amplifier are observed with a minimum noise level 0.7 dB below the usual noise level of the amplifier with its idler mode in a vacuum state. With two correlated quantum fields as the amplifier's inputs and proper adjustment of the gain of the amplifier, it is shown that the amplifier's intrinsic quantum noise can be completely suppressed so that noise-free amplification is achieved. It is also shown that the NOPA, when coupled to either a squeezed state or a nonclassically correlated state, can realize quantum tapping of optical information.

  10. Neural Tube Defects In Mice Exposed To Tap Water

    PubMed Central

    Mallela, Murali K; Werre, Stephen R; Hrubec, Terry C

    2010-01-01

    In May of 2006 we suddenly began to observe neural tube defects (NTDs) in embryos of untreated control mice. We hypothesized the mice were being exposed unknowingly to a teratogenic agent and investigated the cause. Our results suggested that NTDs were not resulting from bedding material, feed, strain or source of the mice. Additionally, mice were negative for routine and comprehensive screens of pathogens. To further test whether the NTDs resulted from infectious or genetic cause localized to our facility, we obtained three strains of timed pregnant mice from commercial suppliers located in 4 different states. All strains and sources of mice arrived in our laboratory with NTDs, implying that commercially available mice were possibly exposed to a teratogen prior to purchase. Our investigation eventually concluded that exposure to tap water was causing the NTDs. The incidence of NTDs was greatest in purchased mice provided tap water and lowest in purchased mice provided distilled deionized water (DDI). Providing mice DDI water for two generations (F2-DDI) eliminated the NTDs. When F2-DDI mice were provided tap water from three different urban areas prior to breeding, their offspring again developed NTDs. Increased length of exposure to tap water significantly increased the incidence of NTDs. These results indicate that a contaminant in municipal tap water is likely causing NTDs in mice. The unknown teratogen appears to have a wide geographic distribution but has not yet been identified. Water analysis is currently underway to identify candidate contaminants that might be responsible for the malformations. PMID:20549630

  11. Novel Polymer Linkers for Single Molecule AFM Force Spectroscopy

    PubMed Central

    Tong, Zenghan; Mikheikin, Andrey; Krasnoslobodtsev, Alexey; Lv, Zhengjian; Lyubchenko, Yuri L.

    2013-01-01

    Flexible polymer linkers play an important role in various imaging and probing techniques that require surface immobilization, including atomic force microscopy (AFM). In AFM force spectroscopy, polymer linkers are necessary for the covalent attachment of molecules of interest to the AFM tip and the surface. The polymer linkers tether the molecules and provide their proper orientation in probing experiments. Additionally, the linkers separate specific interactions from nonspecific short-range adhesion and serve as a reference point for the quantitative analysis of single molecule probing events. In this report, we present our results on the synthesis and testing of a novel polymer linker and the identification of a number of potential applications for its use in AFM force spectroscopy experiments. The synthesis of the linker is based on the well-developed phosphoramidate (PA) chemistry that allows the routine synthesis of linkers with predetermined lengths and PA composition. These linkers are homogeneous in length and can be terminated with various functional groups. PA linkers with different functional groups were synthesized and tested in experimental systems utilizing different immobilization chemistries. We probed interactions between complementary DNA oligonucleotides; DNA and protein complexes formed by the site-specific binding protein SfiI; and interactions between amyloid peptide (Aβ42). The results of the AFM force spectroscopy experiments validated the feasibility of the proposed approach for the linker design and synthesis. Furthermore, the properties of the tether (length, functional groups) can be adjusted to meet the specific requirements for different force spectroscopy experiments and system characteristics, suggesting that it could be used for a large number of various applications. PMID:23624104

  12. Non-reciprocal directional dichroism in the AFM phase of BiFeO3 at THz frequencies

    NASA Astrophysics Data System (ADS)

    Nagel, Urmas; Rõõm, T.; Farkas, D.; Szaller, D.; Bordács, S.; Kézsmárki, I.; Engelkamp, H.; Ozaki, Y.; Tomiaki, Y.; Ito, T.; Fishman, Randy S.

    We did THz absorption spectroscopy of BiFeO3 single crystals in the AFM phase, where the spin cycloid is destroyed in magnetic fields between 18 T and 32 T in Voigt geometry at 1.6 K. If B0 ∥ [ 1 1 0 ] , we see strong directional dichroism (DD) of absorption of the magnon mode with light propagating along the direction of the ferroelectric polarization k ∥ P ∥ [ 111 ] and eω ∥ [ 1 1 0 ] , bω ∥ [ 1 1 2 ] . The sign of DD can be reversed (i) by reversing the direction of B0 or (ii) by flipping the sample, thus reversing the propagation direction of light. The observed effect is caused by the strong magneto-electric coupling in the collinear AFM phase. Research sponsored by the Estonian Ministry of Education and Research (IUT23-3).

  13. Structural Evolution of a Granular Pack under Manual Tapping

    NASA Astrophysics Data System (ADS)

    Iikawa, Naoki; Bandi, Mahesh M.; Katsuragi, Hiroaki

    2015-09-01

    We experimentally study a two-dimensional (2D) granular pack of photoelastic disks subject to vertical manual tapping. Using bright- and dark-field images, we employ gradient-based image analysis methods to analyze various structural quantities. These include the packing fraction (ϕ), force per disk (Fd), and force chain segment length (l) as functions of the tapping number (τ). The increase in the packing fraction with the tapping number is found to exponentially approach an asymptotic value. An exponential distribution is observed for the cumulative numbers of both the force per disk Fd:Ncum(Fd) = AFexp ( - Fd/F0), and the force chain segment length l:Ncum(l) = Alexp ( - l/l0). Whereas the coefficient AF varies with τ for Fd, l shows no dependence on τ. The τ dependences of Fd and ϕ allow us to posit a linear relationship between the total force of the granular pack Ftot*(τ ) and ϕ(τ).

  14. Lattice-resolution imaging of the sapphire (0 0 0 1) surface in air by AFM

    NASA Astrophysics Data System (ADS)

    Gan, Yang; Wanless, Erica J.; Franks, George V.

    2007-02-01

    Lattice-resolution images of single-crystal α-alumina (sapphire) (0 0 0 1) surfaces have been obtained using contact-mode AFM under ambient conditions. It was found that the hexagonal surface lattice has a periodicity of 0.47 ± 0.11 nm, which is identical to that reported previously when the same surface was imaged in water. Large lattice corrugations (as high as 1 nm) were observed, but were concluded to be imaging artifacts because of the strong friction which causes additional deflection of the cantilever. The additional deflection of the cantilever is registered by the detector of the optical beam-deflection AFM resulting in an overestimation of the height at each lattice point. Abrupt changes were also resolved in the topography including honeycomb patterns and a transition from 2D lattices to 1D parallel stripes, with scanning direction. These phenomena can be explained by the commensurate sliding between the tip and sapphire surface due to the strong contact force.

  15. Spontaneous aggregation of humic acid observed with AFM at different pH.

    PubMed

    Colombo, Claudio; Palumbo, Giuseppe; Angelico, Ruggero; Cho, Hyen Goo; Francioso, Ornella; Ertani, Andrea; Nardi, Serenella

    2015-11-01

    Atomic force microscopy in contact (AFM-C) mode was used to investigate the molecular dynamics of leonardite humic acid (HA) aggregate formed at different pH values. HA nanoparticles dispersed at pH values ranging from 2 to 12 were observed on a mica surface under dry conditions. The most clearly resolved and well-resulted AFM images of single particle were obtained at pH 5, where HA appeared as supramolecular particles with a conic shape and a hole in the centre. Those observations suggested that HA formed under these conditions exhibited a pseudo-amphiphilic nature, with secluded hydrophobic domains and polar subunits in direct contact with hydrophilic mica surface. Based on molecular simulation methods, a lignin-carbohydrate complex (LCC) model was proposed to explain the HA ring-like morphology. The LCC model optimized the parameters of β-O-4 linkages between 14 units of 1-4 phenyl propanoid, and resulted in an optimized structure comprising 45-50 linear helical molecules looped spirally around a central cavity. Those results added new insights on the adsorption mechanism of HA on polar surfaces as a function of pH, which was relevant from the point of view of natural aggregation in soil environment. PMID:26295541

  16. Insulated Conducting Cantilevered Nanotips and Two-Chamber Recording System for High Resolution Ion Sensing AFM

    PubMed Central

    Meckes, Brian; Arce, Fernando Teran; Connelly, Laura S.; Lal, Ratnesh

    2014-01-01

    Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels. PMID:24663394

  17. Structure, cell wall elasticity and polysaccharide properties of living yeast cells, as probed by AFM

    NASA Astrophysics Data System (ADS)

    Alsteens, David; Dupres, Vincent; McEvoy, Kevin; Wildling, Linda; Gruber, Hermann J.; Dufrêne, Yves F.

    2008-09-01

    Although the chemical composition of yeast cell walls is known, the organization, assembly, and interactions of the various macromolecules remain poorly understood. Here, we used in situ atomic force microscopy (AFM) in three different modes to probe the ultrastructure, cell wall elasticity and polymer properties of two brewing yeast strains, i.e. Saccharomyces carlsbergensis and S. cerevisiae. Topographic images of the two strains revealed smooth and homogeneous cell surfaces, and the presence of circular bud scars on dividing cells. Nanomechanical measurements demonstrated that the cell wall elasticity of S. carlsbergensis is homogeneous. By contrast, the bud scar of S. cerevisiae was found to be stiffer than the cell wall, presumably due to the accumulation of chitin. Notably, single molecule force spectroscopy with lectin-modified tips revealed major differences in polysaccharide properties of the two strains. Polysaccharides were clearly more extended on S. cerevisiae, suggesting that not only oligosaccharides, but also polypeptide chains of the mannoproteins were stretched. Consistent with earlier cell surface analyses, these findings may explain the very different aggregation properties of the two organisms. This study demonstrates the power of using multiple complementary AFM modalities for probing the organization and interactions of the various macromolecules of microbial cell walls.

  18. STM and AFM; Which is Better for Surface Structural Analysis? Non- contact AFM Studies on Ge/Si(105) Surface

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yukio

    2006-03-01

    Scanning tunneling microscopy (STM) has been utilized to determine surface atomic structure with its highly resolved images. Probing surface electronic states near the Fermi energy (EF), STM images, however, do not necessarily represent the atomic structure of surfaces. It has been believed that atomic force microscopy (AFM) provides us surface topographic images without being disturbed by the electronic states. In order to prove the surpassing performance, we performed noncontact (nc) AFM on the Ge/Si(105) surface [1], which is a facet plane of the ?hut? clusters formed on Ge-deposited Si(001) surface. It is found that STM images taken on the surface, either filled- or empty-state images, do not show all surface atoms because of the electronic effect; some surface atoms have dangling bond states below EF and other surface atoms have states above EF. [2]. In a nc-AFM image, on the other hand, all surface atoms having a dangling bond are observed [3], directly representing an atomic structure of the surface. Electronic information can also be obtained in AFM by using a Kelvin-probe method. From atomically resolved potential profile we obtained, charge transfer among the dangling bond states is directly demonstrated. These results clearly demonstrate that highly-resolved nc-AFM with a Kelvin-probe method is an ideal tool for analysis of atomic structures and electronic properties of surfaces. This work was done in collaboration with T. Eguchi, K. Akiyama, T. An, and M. Ono, ISSP, Univ. Tokyo and JST, Y. Fujikawa and T. Sakurai, IMR. Tohoku Univ. T. Hashimoto, AIST, Y. Morikawa, ISIR, Osaka Univ. K. Terakura, Hokkaido Univ., and M.G. Lagally, University of Wisconsin-Madison. [1] T. Eguchi et al., Phys. Rev. Lett. 93, 266102 (2004). [2] Y. Fujikawa et al., Phys. Rev. Lett. 88, 176101 (2002). [3] T. Eguchi and Y. Hasegawa, Phys. Rev. Lett. 89, 256105 (2002)

  19. High-speed tapping for N/C machining centers

    SciTech Connect

    Friend, J.P.

    1991-11-01

    Through a series of experiments, a new high-speed tapping technique was developed for N/C machining centers. The new technique produces high quality threads in a fraction of the time previously required, using the same equipment. Threads are produced to precise size and depth in a single pass at speeds up to 5000 rpm. Thread sizes ranged from 0.80 UNM (Unified Miniature Thread Series) (0.0315 in. major diameter) to 0.250-20 UN (Unified Screw Threads) in both blind and through-hole applications. The materials tapped included 17-4 PH stainless steel, 300 series stainless steel, and 6061-T6 aluminum. 10 figs.

  20. Femtosecond laser inscription of asymmetric directional couplers for in-fiber optical taps and fiber cladding photonics.

    PubMed

    Grenier, Jason R; Fernandes, Luís A; Herman, Peter R

    2015-06-29

    Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits. PMID:26191688

  1. Interferon Alpha Signalling and Its Relevance for the Upregulatory Effect of Transporter Proteins Associated with Antigen Processing (TAP) in Patients with Malignant Melanoma

    PubMed Central

    Ensslen, Silke; Marquardt, Yvonne; Czaja, Katharina; Joussen, Sylvia; Beer, Daniel; Abele, Rupert; Plewnia, Gabriele; Tampé, Robert; Merk, Hans F.; Hermanns, Heike M.; Baron, Jens M.

    2016-01-01

    Introduction Interferon alpha (IFNα) is routinely used in the clinical practice for adjuvant systemic melanoma therapy. Understanding the molecular mechanism of IFNα effects and prediction of response in the IFNα therapy regime allows initiation and continuation of IFNα treatment for responder and exclusion of non-responder to avoid therapy inefficacy and side-effects. The transporter protein associated with antigen processing-1 (TAP1) is part of the MHC class I peptide-loading complex, and important for antigen presentation in tumor and antigen presenting cells. In the context of personalized medicine, we address this potential biomarker TAP1 as a target of IFNα signalling. Results We could show that IFNα upregulates TAP1 expression in peripheral blood mononuclear cells (PBMCs) of patients with malignant melanoma receiving adjuvant high-dose immunotherapy. IFNα also induced expression of TAP1 in mouse blood and tumor tissue and suppressed the formation of melanoma metastasis in an in vivo B16 tumor model. Besides its expression, TAP binding affinity and transport activity is induced by IFNα in human monocytic THP1 cells. Furthermore, our data revealed that IFNα clearly activates phosphorylation of STAT1 and STAT3 in THP1 and A375 melanoma cells. Inhibition of Janus kinases abrogates the IFNα-induced TAP1 expression. These results suggest that the JAK/STAT pathway is a crucial mediator for TAP1 expression elicited by IFNα treatment. Conclusion We suppose that silencing of TAP1 expression provides tumor cells with a mechanism to escape cytotoxic T-lymphocyte recognition. The observed benefit of IFNα treatment could be mediated by the shown dual effect of TAP1 upregulation in antigen presenting cells on the one hand, and of TAP1 upregulation in ‘silent’ metastatic melanoma cells on the other hand. In conclusion, this work contributes to a better understanding of the mode of action of IFNα which is essential to identify markers to predict, assess and

  2. Wedged AFM-cantilevers for parallel plate cell mechanics.

    PubMed

    Stewart, Martin P; Hodel, Adrian W; Spielhofer, Andreas; Cattin, Cedric J; Müller, Daniel J; Helenius, Jonne

    2013-04-01

    The combination of atomic force microscopy (AFM) and optical microscopy has gained popularity for mechanical analysis of living cells. In particular, recent AFM-based assays featuring tipless cantilevers and whole-cell deformation have yielded insights into cellular function, structure, and dynamics. However, in these assays the standard ≈10° tilt of the cantilever prevents uniaxial loading, which complicates assessment of cellular geometry and can cause cell sliding or loss of loosely adherent cells. Here, we describe an approach to modify tipless cantilevers with wedges and, thereby, achieve proper parallel plate mechanics. We provide guidance on material selection, the wedge production process, property and geometry assessment, and the calibration of wedged cantilevers. Furthermore, we demonstrate their ability to simplify the assessment of cell shape, prevent lateral displacement of round cells during compression, and improve the assessment of cell mechanical properties. PMID:23473778

  3. AFM-based mechanical characterization of single nanofibres.

    PubMed

    Neugirg, Benedikt R; Koebley, Sean R; Schniepp, Hannes C; Fery, Andreas

    2016-04-28

    Nanofibres are found in a broad variety of hierarchical biological systems as fundamental structural units, and nanofibrillar components are playing an increasing role in the development of advanced functional materials. Accurate determination of the mechanical properties of single nanofibres is thus of great interest, yet measurement of these properties is challenging due to the intricate specimen handling and the exceptional force and deformation resolution that is required. The atomic force microscope (AFM) has emerged as an effective, reliable tool in the investigation of nanofibrillar mechanics, with the three most popular approaches-AFM-based tensile testing, three-point deformation testing, and nanoindentation-proving preferable to conventional tensile testing in many (but not all) cases. Here, we review the capabilities and limitations of each of these methods and give a comprehensive overview of the recent advances in this field. PMID:27055900

  4. Insights into Epoxy Network Nanostructural Heterogeneity Using AFM-IR.

    PubMed

    Morsch, Suzanne; Liu, Yanwen; Lyon, Stuart B; Gibbon, Simon R

    2016-01-13

    The first direct observation of a chemically heterogeneous nanostructure within an epoxy resin is reported. Epoxy resins comprise the matrix component of many high performance composites, coatings and adhesives, yet the molecular network structure that underpins the performance of these industrially essential materials is not well understood. Internal nodular morphologies have repeatedly been reported for epoxy resins analyzed using SEM or AFM, yet the origin of these features remains a contentious subject, and epoxies are still commonly assumed to be chemically homogeneous. Uniquely, in this contribution we use the recently developed AFM-IR technique to eliminate previous differences in interpretation, and establish that nodule features correspond to heterogeneous network connectivity within an epoxy phenolic formulation. PMID:26694687

  5. Nano-Bio-Mechanics of Neuroblastoma Cells Using AFM

    NASA Astrophysics Data System (ADS)

    Bastatas, Lyndon; Matthews, James; Kang, Min; Park, Soyeun

    2011-10-01

    We have conducted an in vitro study to determine the elastic moduli of neurobalstoma cell lines using atomic force microscopy. Using a panel of cell lines established from neuroblastoma patients at different stages of disease progress and treatment, we have investigated the differences in elastic moduli during a course of cancer progression and chemotherapy. The cells were grown on the hard substrates that are chemically functionalized to enhance adhesion. We have performed the AFM indentation experiments with different applied forces from the AFM probe. For the purpose of the comparison between cell lines, the indentations were performed only on cell centers. The obtained force-distance curves were analyzed using the Hertz model in order to extract the elastic moduli. We have found that the elastic moduli of human neuroblastoma cells significantly varied during the disease progression. We postulate that the observed difference might be affected by the treatment and chemotherapy.

  6. AFM-based mechanical characterization of single nanofibres

    NASA Astrophysics Data System (ADS)

    Neugirg, Benedikt R.; Koebley, Sean R.; Schniepp, Hannes C.; Fery, Andreas

    2016-04-01

    Nanofibres are found in a broad variety of hierarchical biological systems as fundamental structural units, and nanofibrillar components are playing an increasing role in the development of advanced functional materials. Accurate determination of the mechanical properties of single nanofibres is thus of great interest, yet measurement of these properties is challenging due to the intricate specimen handling and the exceptional force and deformation resolution that is required. The atomic force microscope (AFM) has emerged as an effective, reliable tool in the investigation of nanofibrillar mechanics, with the three most popular approaches--AFM-based tensile testing, three-point deformation testing, and nanoindentation--proving preferable to conventional tensile testing in many (but not all) cases. Here, we review the capabilities and limitations of each of these methods and give a comprehensive overview of the recent advances in this field.

  7. Molecular modeling of enzyme attachment on AFM probes.

    PubMed

    Oliveira, Guedmiller S; Leite, Fabio L; Amarante, Adriano M; Franca, Eduardo F; Cunha, Richard A; Briggs, James M; Freitas, Luiz C G

    2013-09-01

    The immobilization of enzymes on atomic force microscope tip (AFM tip) surface is a crucial step in the development of nanobiosensors to be used in detection process. In this work, an atomistic modeling of the attachment of the acetyl coenzyme A carboxylase (ACC enzyme) on a functionalized AFM tip surface is proposed. Using electrostatic considerations, suitable enzyme-surface orientations with the active sites of the ACC enzyme available for interactions with bulk molecules were found. A 50 ns molecular dynamics trajectory in aqueous solution was obtained and surface contact area, hydrogen bonding and protein stability were analyzed. The enzyme-surface model proposed here with minor adjustment can be applied to study antigen-antibody interactions as well as enzyme immobilization on silica for chromatography applications. PMID:24029365

  8. BOREAS AFM-5 Level-1 Upper Air Network Data

    NASA Technical Reports Server (NTRS)

    Barr, Alan; Hrynkiw, Charmaine; Newcomer, Jeffrey A. (Editor); Hall, Forrest G. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-5 team collected and processed data from the numerous radiosonde flights during the project. The goals of the AFM-05 team were to provide large-scale definition of the atmosphere by supplementing the existing Atmospheric Environment Service (AES) aerological network, both temporally and spatially. This data set includes basic upper-air parameters collected from the network of upper-air stations during the 1993, 1994, and 1996 field campaigns over the entire study region. The data are contained in tabular ASCII files. The level-1 upper-air network data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files also are available on a CD-ROM (see document number 20010000884).

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

    NASA Astrophysics Data System (ADS)

    Feng, Xueling; Kieviet, Bernard D.; Song, Jing; Schön, Peter M.; Vancso, G. Julius

    2014-02-01

    The adherence between silicon nitride AFM tips and redox-active poly(ferrocenylsilanes) (PFS) grafts on gold was investigated by electrochemical AFM force spectroscopy. Before the adhesion measurements silicon nitride AFM probes were cleaned with organic solvents (acetone and ethanol) or piranha solution. Interestingly, these different AFM tip cleaning procedures drastically affected the observed adhesion forces. Water contact angle measurements on the corresponding AFM probe chips showed that piranha treatment resulted in a significant increase of AFM probe chip surface hydrophilicity compared to the organic solvent treatment. Obviously this hydrophilicity change caused drastic, even opposite changes in the tip-PFS adhesive force measurement upon electrode potential change to reversibly oxidize and reduce the PFS grafts. Our findings are of pivotal importance for AFM tip adhesion measurements utilizing standard silicon nitride AFM tips. Probe hydrophilicity must be carefully taken into consideration and controlled.

  10. Obtaining reliable friction data at the nanoscale by tuning AFM parameters

    NASA Astrophysics Data System (ADS)

    Kim, Sung Hyun; Kim, Suenne

    2015-03-01

    Carefully devised experimental study of friction at the nanoscale in dry system is desired for proper mathematical modeling or for quantitative research. Experimentally, contact mode atomic force microscope (AFM) which is able to perform lateral force microscopy (LFM) can be used for acquiring frictional data. To obtain reliable LFM information, we have investigated the effect of scanning parameters, especially gain and scanning rate, on the LFM measurements. Depending on the parameters selected, the relative ratio of the friction force obtained from graphene to that of SiO2 varies greatly from about 1 to 0.1. We will discuss, here, firstly how to understand this behavior and secondly the parameter-optimization procedure for the LFM imaging, which is different from the height imaging, eventually to aid quantitative LFM studies. This research was supported by Basic Science Research Program through NRF of Korea funded by the ministry of Education (2014R1A1A2056555).

  11. LET Spectrum Measurements In CR-39 PNTD With AFM

    NASA Astrophysics Data System (ADS)

    Johnson, C. E.; DeWitt, J. M.; Benton, E. R.; Yasuda, N.; Benton, E. V.

    2011-06-01

    Energetic protons, neutrons, and heavy ions undergoing collisions with target nuclei of varying Z can produce residual heavy recoil fragments via intra-nuclear cascade/evaporation reactions. The particles produced in these non-elastic collisions generally have such extremely short range (˜<10 μm) that they cannot be directly observed by conventional detection methods including CR-39 plastic nuclear track detector (PNTD) that has been chemically etched for analysis by standard visible light microscopy. However, high-LET recoil fragments having range on the order of several cell diameters can be produced in tissue during radiotherapy using proton and carbon beams. We have developed a method to analyze short-range, high-LET tracks in CR-39 plastic nuclear track detector (PNTD) using short duration chemical etching (˜<1 μm) following by automated atomic force microscope (AFM) scanning. The post-scan data processing used in this work was based on semi-automated matrix analysis opposed to traditional grey-scale image analysis. This method takes advantage of the 3-D data obtained via AFM to achieve robust discrimination of nuclear tracks from other features inherently present in the post-etch detector surface. Through automation of AFM scanning, sufficient AFM scan frames were obtained to attain an LET spectrum spanning the LET range from 200-1500 keV/μm. In addition to our experiments, simulations were carried out with the Monte Carlo transport code, FLUKA. To demonstrate this method, CR-39 PNTD was exposed to the proton therapy beam at Loma Linda University Medical Center (LLUMC) at 60 and 230 MeV. Additionally, detectors were exposed to 1 GeV protons at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). For these exposures CR-39 PNTD, Al and Cu target foils were used between detector layers.

  12. AFM and SThM Characterization of Graphene

    NASA Astrophysics Data System (ADS)

    Foy, Christopher; Sidorov, Anton; Chen, Xunchi; Ruan, Ming; Berger, Claire; de Heer, Walter; Jiang, Zhigang

    2012-03-01

    We report on detailed characterization of epitaxial grown graphene on SiC and chemical vapor deposition grown graphene on Cu foil using atomic force microscopy (AFM) and scanning thermal microscopy (SThM). We focus on the electronic and thermal properties of graphene grain boundaries, and thus providing valuable feedback to materials growth. Specifically, we perform thermal conductivity contrast mapping and surface potential mapping of graphene, and compare with that obtained on the Au electrodes and the substrate.

  13. Investigation of biopolymer networks by means of AFM

    NASA Astrophysics Data System (ADS)

    Keresztes, Z.; Rigó, T.; Telegdi, J.; Kálmán, E.

    Natural hydrogel alginate was investigated by means of atomic force microscopy (AFM) to gain microscale information on the morphological and rheological properties of the biopolymer network cross-linked by various cations. Local rheological properties of the gels measured by force spectroscopy gave correlation between increasing ion selectivity and increasing polymer elasticity. Adhesive forces acting between the surface of the gel and the probe, and also the intrinsic rheological properties of bulk polymers affect the microscopical image formation.

  14. LET Spectrum Measurements In CR-39 PNTD With AFM

    SciTech Connect

    Johnson, C. E.; DeWitt, J. M.; Benton, E. R.; Yasuda, N.; Benton, E. V.

    2011-06-01

    Energetic protons, neutrons, and heavy ions undergoing collisions with target nuclei of varying Z can produce residual heavy recoil fragments via intra-nuclear cascade/evaporation reactions. The particles produced in these non-elastic collisions generally have such extremely short range ({approx}<10 {mu}m) that they cannot be directly observed by conventional detection methods including CR-39 plastic nuclear track detector (PNTD) that has been chemically etched for analysis by standard visible light microscopy. However, high-LET recoil fragments having range on the order of several cell diameters can be produced in tissue during radiotherapy using proton and carbon beams. We have developed a method to analyze short-range, high-LET tracks in CR-39 plastic nuclear track detector (PNTD) using short duration chemical etching ({approx}<1 {mu}m) following by automated atomic force microscope (AFM) scanning. The post-scan data processing used in this work was based on semi-automated matrix analysis opposed to traditional grey-scale image analysis. This method takes advantage of the 3-D data obtained via AFM to achieve robust discrimination of nuclear tracks from other features inherently present in the post-etch detector surface. Through automation of AFM scanning, sufficient AFM scan frames were obtained to attain an LET spectrum spanning the LET range from 200-1500 keV/{mu}m. In addition to our experiments, simulations were carried out with the Monte Carlo transport code, FLUKA. To demonstrate this method, CR-39 PNTD was exposed to the proton therapy beam at Loma Linda University Medical Center (LLUMC) at 60 and 230 MeV. Additionally, detectors were exposed to 1 GeV protons at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). For these exposures CR-39 PNTD, Al and Cu target foils were used between detector layers.

  15. Quantitative nano-mechanics of biological cells with AFM

    NASA Astrophysics Data System (ADS)

    Sokolov, Igor

    2013-03-01

    The importance of study of living cells is hard to overestimate. Cell mechanics is a relatively young, yet not a well-developed area. Besides just a fundamental interest, large practical need has emerged to measure cell mechanics quantitatively. Recent studies revealed a significant correlation between stiffness of biological cells and various human diseases, such as cancer, malaria, arthritis, and even aging. However, really quantitative studies of mechanics of biological cells are virtually absent. It is not even clear if the cell, being a complex and heterogeneous object, can be described by the elastic modulus at all. Atomic force microscopy (AFM) is a natural instrument to study properties of cells in their native environments. Here we will demonstrate that quantitative measurements of elastic modulus of cells with AFM are possible. Specifically, we will show that the ``cell body'' (cell without ``brush'' surface layer, a non-elastic layer surrounding cells) typically demonstrates the response of a homogeneous elastic medium up to the deformation of 10-20%, but if and only if a) the cellular brush layer is taken into account, b) rather dull AFM probes are used. This will be justified with the help of the strong condition of elastic behavior of material: the elastic modulus is shown to be independent on the indentation depth. We will also demonstrate that an attempt either to ignore the brush layer or to use sharp AFM probes will result in the violation of the strong condition, which implies impossibility to use the concept of the elastic modulus to describe cell mechanics in such experiments. Examples of quantitative measurements of the Young's modulus of the cell body and the cell brush parameters will be given for various cells. Address when submitting: Clarkson University, Potsdam, NY 13699

  16. LET spectrum measurements in Cr-39 PNTD with AFM

    SciTech Connect

    Johnson, Carl Edward; De Witt, Joel M; Benton, Eric R; Yasuda, Nakahiro; Benton, Eugene V

    2010-01-01

    Energetic protons, neutrons, and heavy ions undergoing collisions with target nuclei of varying Z can produce residual heavy recoil fragments via intra-nuclear cascade/evaporation reactions. The particles produced in these non-elastic collisions generally have such extremely short range ({approx}< 10 {mu}m) that they cannot be directly observed by conventional detection methods including CR-39 plastic nuclear track detector (PNTD) that has been chemically etched for analysis by standard visible light microscopy. However, high-LET recoil fragments having range on the order of several cell diameters can be produced in tissue during radiotherapy using proton and carbon beams. We have developed a method to analyze short-range, high-LET tracks in CR-39 plastic nuclear track detector (PNTD) using short duration chemical etching ({approx}< 1 {mu}m) followed by automated atomic force microscope (AFM) scanning. The post-scan data processing used in this work was based on semi-automated matrix analysis opposed to traditional grey-scale image analysis. This method takes advantage of the 3-D data obtained via AFM to achieve robust discrimination of nuclear tracks from other features. Through automation of AFM scanning, sufficient AFM scan frames were obtained to attain an LET spectrum spanning the LET range from 200-1500 keV/{mu}m. In addition to our experiments, simulations were carried out with the Monte Carlo transport code, FLUKA. To demonstrate this method, CR-39 PNTD was exposed to the proton therapy beam at Loma Linda University Medical Center (LLUMC) at 60 and 230 MeV. Additionally, detectors were exposed to I GeV protons at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). For these exposures CR-39 PNTD, Al and Cu target foils were used between detector layers.

  17. Near-Field Spectroscopy with Nanoparticles Deposited by AFM

    NASA Technical Reports Server (NTRS)

    Anderson, Mark S.

    2008-01-01

    An alternative approach to apertureless near-field optical spectroscopy involving an atomic-force microscope (AFM) entails less complexity of equipment than does a prior approach. The alternative approach has been demonstrated to be applicable to apertureless near-field optical spectroscopy of the type using an AFM and surface enhanced Raman scattering (SERS), and is expected to be equally applicable in cases in which infrared or fluorescence spectroscopy is used. Apertureless near-field optical spectroscopy is a means of performing spatially resolved analyses of chemical compositions of surface regions of nanostructured materials. In apertureless near-field spectroscopy, it is common practice to utilize nanostructured probe tips or nanoparticles (usually of gold) having shapes and dimensions chosen to exploit plasmon resonances so as to increase spectroscopic-signal strengths. To implement the particular prior approach to which the present approach is an alternative, it is necessary to integrate a Raman spectrometer with an AFM and to utilize a special SERS-active probe tip. The resulting instrumentation system is complex, and the tasks of designing and constructing the system and using the system to acquire spectro-chemical information from nanometer-scale regions on a surface are correspondingly demanding.

  18. Tissue section AFM: In situ ultrastructural imaging of native biomolecules

    PubMed Central

    Graham, Helen K.; Hodson, Nigel W.; Hoyland, Judith A.; Millward-Sadler, Sarah J.; Garrod, David; Scothern, Anthea; Griffiths, Christopher E.M.; Watson, Rachel E.B.; Cox, Thomas R.; Erler, Janine T.; Trafford, Andrew W.; Sherratt, Michael J.

    2010-01-01

    Conventional approaches for ultrastructural high-resolution imaging of biological specimens induce profound changes in bio-molecular structures. By combining tissue cryo-sectioning with non-destructive atomic force microscopy (AFM) imaging we have developed a methodology that may be applied by the non-specialist to both preserve and visualize bio-molecular structures (in particular extracellular matrix assemblies) in situ. This tissue section AFM technique is capable of: i) resolving nm–µm scale features of intra- and extracellular structures in tissue cryo-sections; ii) imaging the same tissue region before and after experimental interventions; iii) combining ultrastructural imaging with complimentary microscopical and micromechanical methods. Here, we employ this technique to: i) visualize the macro-molecular structures of unstained and unfixed fibrillar collagens (in skin, cartilage and intervertebral disc), elastic fibres (in aorta and lung), desmosomes (in nasal epithelium) and mitochondria (in heart); ii) quantify the ultrastructural effects of sequential collagenase digestion on a single elastic fibre; iii) correlate optical (auto fluorescent) with ultrastructural (AFM) images of aortic elastic lamellae. PMID:20144712

  19. AFM imaging of functionalized carbon nanotubes on biological membranes

    NASA Astrophysics Data System (ADS)

    Lamprecht, C.; Liashkovich, I.; Neves, V.; Danzberger, J.; Heister, E.; Rangl, M.; Coley, H. M.; McFadden, J.; Flahaut, E.; Gruber, H. J.; Hinterdorfer, P.; Kienberger, F.; Ebner, A.

    2009-10-01

    Multifunctional carbon nanotubes are promising for biomedical applications as their nano-size, together with their physical stability, gives access into the cell and various cellular compartments including the nucleus. However, the direct and label-free detection of carbon nanotube uptake into cells is a challenging task. The atomic force microscope (AFM) is capable of resolving details of cellular surfaces at the nanometer scale and thus allows following of the docking of carbon nanotubes to biological membranes. Here we present topographical AFM images of non-covalently functionalized single walled (SWNT) and double walled carbon nanotubes (DWNT) immobilized on different biological membranes, such as plasma membranes and nuclear envelopes, as well as on a monolayer of avidin molecules. We were able to visualize DWNT on the nuclear membrane while at the same time resolving individual nuclear pore complexes. Furthermore, we succeeded in localizing individual SWNT at the border of incubated cells and in identifying bundles of DWNT on cell surfaces by AFM imaging.

  20. Oxide nanocrystal based nanocomposites for fabricating photoplastic AFM probes.

    PubMed

    Ingrosso, Chiara; Martin-Olmos, Cristina; Llobera, Andreu; Innocenti, Claudia; Sangregorio, Claudio; Striccoli, Marinella; Agostiano, Angela; Voigt, Anja; Gruetzner, Gabi; Brugger, Jürgen; Perez-Murano, Francesc; Curri, Maria Lucia

    2011-11-01

    We report on the synthesis, characterization and application of a novel nanocomposite made of a negative tone epoxy based photoresist modified with organic-capped Fe(2)O(3) nanocrystals (NCs). The mechanical properties of the nanocomposite drastically improve upon incorporation of a suitable concentration of NCs in the polymer, without deteriorating its photolithography performance. High aspect ratio 3D microstructures made of the nanocomposite have been fabricated with a uniform surface morphology and with a resolution down to few micrometres. The embedded organic-capped Fe(2)O(3) NCs drastically increase the stiffness and hardness of the epoxy based photoresist matrix, making the final material extremely interesting for manufacturing miniaturized polymer based mechanical devices and systems. In particular, the nanocomposite has been used as structural material for fabricating photoplastic Atomic Force Microscopy (AFM) probes with integrated tips showing outstanding mechanical response and high resolution imaging performance. The fabricated probes consist of straight cantilevers with low stress-gradient and high quality factors, incorporating sharp polymeric tips. They present considerably improved performance compared to pure epoxy based photoresist AFM probes, and to commercial silicon AFM probes. PMID:21858377

  1. Modeling of Manganese Ferroalloy Slag Properties and Flow During Tapping

    NASA Astrophysics Data System (ADS)

    Muller, Jacques; Zietsman, Johannes Hendrik; Pistorius, Petrus Christiaan

    2015-12-01

    Stable operation of submerged-arc furnaces producing high-carbon ferromanganese (HCFeMn) and silicomanganese (SiMn) requires tapping of consistent amounts of liquid slag and metal. Minimal effort to initiate and sustain tapping at reasonable rates is desired, accommodating fluctuations in especially slag chemical composition and temperature. An analytical model is presented that estimates the tapping rate of the liquid slag-metal mixture as a function of taphole dimensions, coke bed particulate properties, and slag and metal physicochemical properties with dependencies on chemical composition and temperature. This model may be used to evaluate the sensitivity to fluctuations in these parameters, and to determine the influence of converting between HCFeMn and SiMn production. The model was applied to typical HCFeMn and SiMn process conditions, using modeled slag viscosities and densities. Tapping flow rates estimated were comparable to operational data and found to be dependent mostly on slag viscosity. Slag viscosities were generally lower for typical SiMn slags due to the higher temperature used for calculating viscosity. It was predicted that flow through the taphole would mostly develop into laminar flow, with the pressure drop predominantly over the coke bed. Flow rates were found to be more dependent on the taphole diameter than on the taphole length.

  2. 20. Detail, Furnace A, shows the drill used to tap ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Detail, Furnace A, shows the drill used to tap the furnace (at center left) and the 'mud gun' used to close it up with a clay plug (at lower right). Metal chute at center (next to drill) was used to clean out furnace prior to its abandonment. - Central Furnaces, 2650 Broadway, east bank of Cuyahoga River, Cleveland, Cuyahoga County, OH

  3. Media Leader Tapped to Head New York City Schools

    ERIC Educational Resources Information Center

    Samuels, Christina A.

    2010-01-01

    When Mayor Michael R. Bloomberg sought a leader for the New York City schools in 2002, his outside-the-box choice was Joel I. Klein, a former assistant U.S. attorney general who had no experience as a school administrator. Eight years later, in seeking a replacement for Mr. Klein, Mr. Bloomberg has tapped yet another person from outside education:…

  4. Guide to Implementing TAP. Teens for AIDS Prevention Project.

    ERIC Educational Resources Information Center

    Center for Population Options, Washington, DC.

    Teens for AIDS Prevention (TAP) is a model peer intervention program designed by the Center for Population Options to increase knowledge and change attitudes and behaviors among youth to reduce their risk of Human Immunodeficiency Virus (HIV) infection. The program utilizes peer pressure in a positive sense: to encourage youth to protect…

  5. 17. SOUTHEAST VIEW OF THE TAPPING SIDE OF BASIC OXYGEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. SOUTHEAST VIEW OF THE TAPPING SIDE OF BASIC OXYGEN FURNACE No. 2 ON THE OPERATING FLOOR OF THE FURNACE AISLE IN THE BOP SHOP. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  6. Multiplication of Legionella spp. in tap water containing Hartmannella vermiformis.

    PubMed Central

    Wadowsky, R M; Wilson, T M; Kapp, N J; West, A J; Kuchta, J M; States, S J; Dowling, J N; Yee, R B

    1991-01-01

    A model was developed to study the multiplication of various Legionella spp. in tap water containing Hartmannella vermiformis. Tap water cultures prepared with the following components were suitable for the multiplication studies: Legionella spp., 10(3) CFU/ml; H. vermiformis, 10(4.4) cysts per ml; and killed Pseudomonas paucimobilis, 10(9) cells per ml. Cocultures were incubated at 37 degrees C for at least 1 week. The following legionellae multiplied in tap water cocultures in each replicate experiment: L. bozemanii (WIGA strain), L. dumoffii (NY-23 and TX-KL strains), L. micdadei (two environmental strains), and L. pneumophila (six environmental strains and one clinical isolate). Growth yield values for these strains were 0.6 to 3.5 log CFU/ml. Legionellae which did not multiply in replicate cocultures included L. anisa (one strain), L. bozemanii (MI-15 strain), L. micdadei (a clinical isolate), L. longbeachae, (one strain), and L. pneumophila (Philadelphia 1 strain). L. gormanii and an environmental isolate of L. pneumophila multiplied in only one of three experiments. None of the legionellae multiplied in tap water containing only killed P. paucimobilis. The mean growth yield (+/- standard deviation) of H. vermiformis in the cocultures was 1.2 +/- 0.1 log units/ml. H. vermiformis supports multiplication of only particular strains of legionellae, some of which are from diverse origins. PMID:1892386

  7. 9. Tower building. Hot water tap floor shown. Mixing vat ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Tower building. Hot water tap floor shown. Mixing vat at center level. Juices mix and flow and left lower level. Copper kettles are down below view level. Looking toward front of building. - Tivoli-Union Brewery, 1320-1348 Tenth Street, Denver, Denver County, CO

  8. "Bottled or Tap?" A Controversy for Science, Economics, and Society

    ERIC Educational Resources Information Center

    Lapham, Steven S.

    2009-01-01

    Every year, Americans spend billions of dollars on bottled water. They purchase a bottle from the vending machine or buy a case at the grocery, no longer considering the water that's freely available from their taps. As consumers and as citizens, however, Americans should pause to study the personal and public consequences of this choice. In this…

  9. 49 CFR 192.627 - Tapping pipelines under pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Tapping pipelines under pressure. 192.627 Section 192.627 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION...

  10. Tapping a Potential for the Good of All.

    ERIC Educational Resources Information Center

    Rabo, Annika

    Historically, the spread of universal formal mass education in the West is closely linked to emergence of nation-states. This is also true of the Third World. The salient feature of education today is that it reflects a model of society in which citizens, including children, are seen as a potential to be tapped for development of the nation, as…

  11. Cascaded Amplifying Quantum Optical Taps: A Robust Noiseless Optical Bus

    SciTech Connect

    Bencheikh, K.; Simonneau, C.; Levenson, J.A.

    1997-01-01

    Two identical amplifying quantum optical taps, based on noiseless optical parametric amplification and twin beam quantum correlation, have been implemented in a series configuration and experimentally investigated. The result is an optical bus which we have shown to be robust with respect to downstream losses. {copyright} {ital 1996} {ital The American Physical Society}

  12. TRIHALOMETHANE LEVELS IN HOME TAP WATER AND SEMEN QUALITY

    EPA Science Inventory

    Trihalomethane Levels in Home Tap Water and Semen Quality
    Laura Fenster, 1 Kirsten Waller, 2 Gayle Windham, 1 Tanya Henneman, 2 Meredith Anderson, 2 Pauline Mendola, 3 James W. Overstreet, 4 Shanna H. Swan5

    1California Department of Health Services, Division of Environm...

  13. TAp73 is a central transcriptional regulator of airway multiciliogenesis.

    PubMed

    Nemajerova, Alice; Kramer, Daniela; Siller, Saul S; Herr, Christian; Shomroni, Orr; Pena, Tonatiuh; Gallinas Suazo, Cristina; Glaser, Katharina; Wildung, Merit; Steffen, Henrik; Sriraman, Anusha; Oberle, Fabian; Wienken, Magdalena; Hennion, Magali; Vidal, Ramon; Royen, Bettina; Alevra, Mihai; Schild, Detlev; Bals, Robert; Dönitz, Jürgen; Riedel, Dietmar; Bonn, Stefan; Takemaru, Ken-Ichi; Moll, Ute M; Lizé, Muriel

    2016-06-01

    Motile multiciliated cells (MCCs) have critical roles in respiratory health and disease and are essential for cleaning inhaled pollutants and pathogens from airways. Despite their significance for human disease, the transcriptional control that governs multiciliogenesis remains poorly understood. Here we identify TP73, a p53 homolog, as governing the program for airway multiciliogenesis. Mice with TP73 deficiency suffer from chronic respiratory tract infections due to profound defects in ciliogenesis and complete loss of mucociliary clearance. Organotypic airway cultures pinpoint TAp73 as necessary and sufficient for basal body docking, axonemal extension, and motility during the differentiation of MCC progenitors. Mechanistically, cross-species genomic analyses and complete ciliary rescue of knockout MCCs identify TAp73 as the conserved central transcriptional integrator of multiciliogenesis. TAp73 directly activates the key regulators FoxJ1, Rfx2, Rfx3, and miR34bc plus nearly 50 structural and functional ciliary genes, some of which are associated with human ciliopathies. Our results position TAp73 as a novel central regulator of MCC differentiation. PMID:27257214

  14. MALLEABLE IRON BULL LADLE, HOLDS IRON AFTER IT IS TAPPED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MALLEABLE IRON BULL LADLE, HOLDS IRON AFTER IT IS TAPPED OUT OF THE CUPOLA UNTIL IT NEEDED BY POURERS ON THE CONVEYOR LINES WHO FILL MOBILE LADLES ATTACHED TO OVERHEAD RAIL SYSTEMS AS THE BULL LADLE TIPS. - Stockham Pipe & Fittings Company, Malleable Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  15. Two Axis Pointing System (TAPS) attitude acquisition, determination, and control

    NASA Technical Reports Server (NTRS)

    Azzolini, John D.; Mcglew, David E.

    1990-01-01

    The Two Axis Pointing System (TAPS) is a 2 axis gimbal system designed to provide fine pointing of Space Transportation System (STS) borne instruments. It features center-of-mass instrument mounting and will accommodate instruments of up to 1134 kg (2500 pounds) which fit within a 1.0 by 1.0 by 4.2 meter (40 by 40 by 166 inch) envelope. The TAPS system is controlled by a microcomputer based Control Electronics Assembly (CEA), a Power Distribution Unit (PDU), and a Servo Control Unit (SCU). A DRIRU-II inertial reference unit is used to provide incremental angles for attitude propagation. A Ball Brothers STRAP star tracker is used for attitude acquisition and update. The theory of the TAPS attitude determination and error computation for the Broad Band X-ray Telescope (BBXRT) are described. The attitude acquisition is based upon a 2 star geometric solution. The acquisition theory and quaternion algebra are presented. The attitude control combines classical position, integral and derivative (PID) control with techniques to compensate for coulomb friction (bias torque) and the cable harness crossing the gimbals (spring torque). Also presented is a technique for an adaptive bias torque compensation which adjusts to an ever changing frictional torque environment. The control stability margins are detailed, with the predicted pointing performance, based upon simulation studies. The TAPS user interface, which provides high level operations commands to facilitate science observations, is outlined.

  16. Design Approaches and Comparison of TAPS Packages for Engineering

    ERIC Educational Resources Information Center

    Sidhu, S. Manjit

    2007-01-01

    Purpose: The paper's purpose is to promote the use of modern technologies such as multimedia packages to engineering students. The aim is to help them to learning in their learning, visualization, problem solving and understanding engineering concepts such as in mechanics dynamics. Design/methodology/approach: TAPS packages are developed to help…

  17. Poliovirus concentration from tap water with electropositive adsorbent filters.

    PubMed

    Sobsey, M D; Glass, J S

    1980-08-01

    Simple, reliable, and efficient concentration of poliovirus from tap water was obtained with two types of electropositive filter media, one of which is available in the form of a pleated cartridge filter (Virozorb 1MDS). Virus adsorption from tap water between pH 3.5 and 7.5 was more efficient with electropositive filters than with Filterite filters. Elution of adsorbed viruses was more efficient with beef extract in glycine, pH 9.5, than with glycine-NaOH, pH 11.0. In paired comparative studies, electropositive filters, with adsorption at pH 7.5 and no added polyvalent cation salts, gave less variable virus concentration efficiencies than did Filterite filters with adsorption at pH 3.5 plus added MgCl2. Recovery of poliovirus from 1,000-liter tap water volumes was approximately 30% efficient with both Virozorb 1MDS and Filterite pleated cartridge filters, but the former were much simpler to use. The virus adsorption behavior of these filters appears to be related to their surface charge properties, with more electropositive filters giving more efficient virus adsorption from tap water at higher pH levels. PMID:6258472

  18. 37. Tap room with bar, looking from east to west ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. Tap room with bar, looking from east to west showing part of the mural (on north wall) depicting nautical and whaling themes. (mural and bar were removed 1998 - 99 respectively.) - Fort Ord, Soldiers' Club, California State Highway 1 near Eighth Street, Seaside, Monterey County, CA

  19. Complexity matching effects in bimanual and interpersonal syncopated finger tapping.

    PubMed

    Coey, Charles A; Washburn, Auriel; Hassebrock, Justin; Richardson, Michael J

    2016-03-11

    The current study was designed to investigate complexity matching during syncopated behavioral coordination. Participants either tapped in (bimanual) syncopation using their two hands, or tapped in (interpersonal) syncopation with a partner, with each participant using one of their hands. The time series of inter-tap intervals (ITI) from each hand were submitted to fractal analysis, as well as to short-term and multi-timescale cross-correlation analyses. The results demonstrated that the fractal scaling of one hand's ITI was strongly correlated to that of the other hand, and this complexity matching effect was stronger in the bimanual condition than in the interpersonal condition. Moreover, the degree of complexity matching was predicted by the strength of short-term cross-correlation and the stability of the asynchrony between the two tapping series. These results suggest that complexity matching is not specific to the inphase synchronization tasks used in past research, but is a general result of coordination between complex systems. PMID:26840612

  20. Effects of lateral tip control in CD-AFM width metrology

    NASA Astrophysics Data System (ADS)

    Dixson, Ronald; Ng, Boon Ping; Orji, Ndubuisi

    2014-09-01

    Critical dimension atomic force microscopes (CD-AFMs) use flared tips and two-dimensional sensing and position control of the tip-sample interaction to enable scanning of features with near-vertical or reentrant sidewalls. Sidewall sensing usually involves lateral dither of the tip, which was the case in the first two generations of CD-AFM. Current, third-generation instruments also have a fast dither tube actuation (FDTA) mode where a control algorithm and fast response piezo actuator are used to position the tip in a manner that resembles touch-triggering of coordinate measuring machines (CMMs). All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. When lateral dithering is involved, this effect is readily understood as the addition of a dither envelope to the geometrical tip width. The effective tip width is a key correction parameter for accurate feature width measurements and is typically estimated using a tip calibration procedure. However, the possibility exists of small errors in the estimated tip width due to variations and dependencies of the effective width on tip, tool, material, and environmental parameters. We are investigating this possibility through a systematic study of the dependence of the apparent width on measurement mode, dither amplitude, tip type, and sample composition. While we believe that there are potential effects that should be considered carefully, we also conclude, particularly for silicon features, that most potential biases can be removed by performing the calibration and measurement exercises under the same conditions.

  1. BIOMECHANICAL EVALUATION OF THE INFLUENCE OF CERVICAL SCREWS TAPPING AND DESIGN

    PubMed Central

    Silva, Patricia; Rosa, Rodrigo César; Shimano, Antonio Carlos; Albuquerque de Paula, Francisco José; Volpon, José Batista; Aparecido Defino, Helton Luiz

    2015-01-01

    Objective: To assess if the screw design (self-drilling/self-tapping) and the pilot hole tapping could affect the insertion torque and screw pullout strength of the screw used in anterior fixation of the cervical spine. Methods: Forty self-tapping screws and 20 self-drilling screws were inserted into 10 models of artificial bone and 10 cervical vertebrae of sheep. The studied parameters were the insertion torque and pullout strength. The following groups were created: Group I-self-tapping screw insertion after pilot hole drilling and tapping; Group II-self-tapping screw insertion after pilot hole drilling without tapping; Group III-self-drilling screw insertion without drilling and tapping. In Groups I and II, the pilot hole had 14.0 mm in depth and was made with a 3mmn drill, while tapping was made with a 4mm tap. The insertion torque was measured and the pullout test was performed. The comparison between groups was made considering the mean insertion torque and the maximum mean pullout strength with the variance analysis (ANOVA; p≤ 0.05). Results: Previous drilling and tapping of pilot hole significantly decreased the insertion torque and the pullout strength. Conclusion: The insertion torque and pullout strength of self-drilling screws were significantly higher when compared to self-tapping screws inserted after pilot hole tapping. PMID:27004189

  2. Phthalate occurrence in rivers and tap water from central Spain.

    PubMed

    Domínguez-Morueco, N; González-Alonso, S; Valcárcel, Y

    2014-12-01

    The aim of this study is to evaluate the presence and concentrations of the main phthalates in water from the Jarama and Manzanares rivers in the region of Madrid (RM, Central Spain), the most densely populated region of Spain, and to determine the possible oestrogenic activity based on found phthalate concentration. The presence of phthalates in major supply drinking water areas of the RM was also analysed, thus allowing a preliminary assessment of the health risks resulting from the concentrations obtained. The results of this study show the presence of the three (dimethyl phthalate (DMP), diethyl phthalate (DEP) di-n-butyl phthalate (DBP)) of five phthalates studied (dimethyl phthalate (DMP), diethyl phthalate (DEP), di-(2-ethylhexyl) phthalate (DEHP), benzyl-butyl phthalate (BBP) and di-n-butyl phthalate (DBP)). The DBP was found in both river and tap water samplers, whereas DMP and DEP were found in only drinking water samples. The DBP was found to make the highest average contribution to pollution in both river and tap water. The DEHP was not found in both the river and tap water because it is one of the most regulated phthalates. The highest phthalate contamination was found in the Manzanares river and in those areas that receive treated water from the Tagus river. The phthalates found in river and tap water in the RM do not represent a potential oestrogenic risk for the aquatic environment or humans. A preliminary risk assessment suggested that the risk of exposure to phthalates from tap water in this study is acceptable, although continuous monitoring of the presence of these substances in both drinking and river water should be undertaken to detect possible increases in their concentrations. This is the first study to analyse the presence of phthalates in both rivers and drinking water of the centre of Spain. PMID:25217752

  3. A Swing Level Controlled Transmitter for Single-Ended Signaling with Center-Tapped Termination

    NASA Astrophysics Data System (ADS)

    Jang, Young-Chan

    A swing level controlled voltage-mode transmitter is proposed to support a stub series-terminated logic channel with center-tapped termination. This transmitter provides a swing level control to support the diagnostic mode and improve the signal integrity in the absence of the destination termination. By using the variable parallel termination, the proposed transmitter maintains the constant output impedance of the source termination while the swing level is controlled. Also, the series termination using an external resistor is used to reduce the impedance mismatch effect due to the parasitic components of the capacitor and inductor. To verify the proposed transmitter, the voltage-mode driver, which provides eight swing levels with the constant output impedance of about 50Ω, was implemented using a 70nm 1-poly 3-metal DRAM process with a 1.5V supply. The jitter reduction of 54% was measured with the swing level controlled voltage-mode driver in the absence of the destination termination at 1.6-Gb/s.

  4. AFM and SEM study of the effects of etching on IPS-Empress 2 TM dental ceramic

    NASA Astrophysics Data System (ADS)

    Luo, X.-P.; Silikas, N.; Allaf, M.; Wilson, N. H. F.; Watts, D. C.

    2001-10-01

    The aim of this study was to investigate the effects of increasing etching time on the surface of the new dental material, IPS-Empress 2 TM glass ceramic. Twenty one IPS-Empress 2 TM glass ceramic samples were made from IPS-Empress 2 TM ingots through lost-wax, hot-pressed ceramic fabrication technology. All samples were highly polished and cleaned ultrasonically for 5 min in acetone before and after etching with 9.6% hydrofluoric acid gel. The etching times were 0, 10, 20, 30, 60, 90 and 120 s respectively. Microstructure was analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to evaluate the surface roughness and topography. Observations with SEM showed that etching with hydrofluoric acid resulted in preferential dissolution of glass matrix, and that partially supported crystals within the glass matrix were lost with increasing etching time. AFM measurements indicated that etching increased the surface roughness of the glass-ceramic. A simple least-squares linear regression was used to establish a relationship between surface roughness parameters ( Ra, RMS), and etching time, for which r2>0.94. This study demonstrates the benefits of combining two microscopic methods for a better understanding of the surface. SEM showed the mode of action of hydrofluoric acid on the ceramic and AFM provided valuable data regarding the extent of surface degradation relative to etching time.

  5. Reconciling measurements in AFM reference metrology when using different probing techniques

    NASA Astrophysics Data System (ADS)

    Rana, Narender; Archie, Charles; Foucher, Johann

    2011-03-01

    CD-AFM can report CD measurements to several nanometer differences when different probing techniques including probe types, scan methods, or data analyses are employed on the same sample despite using standard calibration techniques. This potentially weakens the assertion that this instrument is inherently accurate. It is particularly important to resolve these discrepancies given the measurement challenges where multiple probing techniques need to be employed to get complete CD information. Probe type refers to tip construction methods that can significantly affect geometrical aspects of probe such as effective length, width, and edge height as well as material composition and coating. Scan code refers to CD or DT mode of tool operation. Analysis includes probe geometry deconvolution and measurement algorithms. These challenges in measurement accuracy are especially significant for the foot or bottom CD metrology of 3D structures. This paper explores the impact of these different probing techniques on the measurement accuracy. In one series of experiments, measurements for different probing techniques are compared when the test and the referencing structures are composed of similar material and possess smooth vertical profiles. The investigation is then extended to explore the accuracy of bottom CD measurement of non vertical profiles encountered in actual process development. A hybrid method using CD and DT modes has been tested to measure the bottom CD of challenging pitch structures. The limited space for the probe is particularly problematic for CD mode but the accuracy of DT mode for CD measurement is a concern. Other challenges will also be discussed along with possible solutions. CD-AFM has increased uncertainty when it comes to measuring within 15 nm of the bottom of a structure. In this regime details of the shape of the probe and the method by which this shape is extracted from the raw data become important. Measured CDs can vary by a few nanometers

  6. Spatial dependence of polycrystalline FTO’s conductance analyzed by conductive atomic force microscope (C-AFM)

    SciTech Connect

    Peixoto, Alexandre Pessoa; Costa, J. C. da

    2014-05-15

    Fluorine-doped Tin oxide (FTO) is a highly transparent, electrically conductive polycrystalline material frequently used as an electrode in organic solar cells and optical-electronic devices [1–2]. In this work a spatial analysis of the conductive behavior of FTO was carried out by Conductive-mode Atomic Force Microscopy (C-AFM). Rare highly oriented grains sample give us an opportunity to analyze the top portion of polycrystalline FTO and compare with the border one. It is shown that the current flow essentially takes place through the polycrystalline edge at grain boundaries.

  7. TAPS: an automated tool for identification of skills, knowledges, and abilities using natural language task description

    SciTech Connect

    Jorgensen, C.C.; Carter, R.J.

    1986-01-01

    A prototype, computer-based tool (TAPS) has been developed to aid training system developers in identifying skills, knowledges, and abilities (SKAs) during task analysis. TAPS uses concepts of flexible pattern matching to evaluate English descriptions of job behaviors and to recode them as SKA lists. This paper addresses the rationale for TAPS and describes its design including SKA definitions and task analysis logic. It also presents examples of TAPS's application.

  8. The Ability to Tap to a Beat Relates to Cognitive, Linguistic, and Perceptual Skills

    ERIC Educational Resources Information Center

    Tierney, Adam T.; Kraus, Nina

    2013-01-01

    Reading-impaired children have difficulty tapping to a beat. Here we tested whether this relationship between reading ability and synchronized tapping holds in typically-developing adolescents. We also hypothesized that tapping relates to two other abilities. First, since auditory-motor synchronization requires monitoring of the relationship…

  9. Oropharyngeal Tularemia Outbreak Associated with Drinking Contaminated Tap Water, Turkey, July–September 2013

    PubMed Central

    Celebi, Bekir; Isik, Mehmet Emirhan; Tutus, Celal; Ozturk, Huseyin; Temel, Fehminaz; Kizilaslan, Mecit; Zhu, Bao-Ping

    2015-01-01

    In 2013, an oropharyngeal tularemia outbreak in Turkey affected 55 persons. Drinking tap water during the likely exposure period was significantly associated with illness (attack rate 27% vs. 11% among non–tap water drinkers). Findings showed the tap water source had been contaminated by surface water, and the chlorination device malfunctioned. PMID:26584074

  10. 40 CFR 141.86 - Monitoring requirements for lead and copper in tap water.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... copper in tap water. 141.86 Section 141.86 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 141.86 Monitoring requirements for lead and copper in tap water. (a) Sample site location. (1) By the... the water system can collect the number of lead and copper tap samples required in paragraph (c)...

  11. 40 CFR 141.86 - Monitoring requirements for lead and copper in tap water.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... copper in tap water. 141.86 Section 141.86 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 141.86 Monitoring requirements for lead and copper in tap water. (a) Sample site location. (1) By the... the water system can collect the number of lead and copper tap samples required in paragraph (c)...

  12. 40 CFR 141.86 - Monitoring requirements for lead and copper in tap water.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... copper in tap water. 141.86 Section 141.86 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 141.86 Monitoring requirements for lead and copper in tap water. (a) Sample site location. (1) By the... the water system can collect the number of lead and copper tap samples required in paragraph (c)...

  13. TAp63 suppress metastasis via miR-133b in colon cancer cells

    PubMed Central

    Lin, C W; Li, X R; Zhang, Y; Hu, G; Guo, Y H; Zhou, J Y; Du, J; Lv, L; Gao, K; Zhang, Y; Deng, H

    2014-01-01

    Background: TAp63 is a tumour-suppressor protein that is often underexpressed in various types of cancer. It has been shown to activate gene transcription depending on the transcription domain and to be closely related with metastasis. In this study, we demonstrate that TAp63 suppresses metastasis in colon cancer cells through microRNA-133b. Methods: We evaluated the correlation of TAp63 and miR-133b with HT-29 and SW-620 cells and investigated the roles of TAp63 in the expression of RhoA, E-cadherin and vimentin. We further investigated the roles of TAp63-mediated invasion and migration of colon cancer cells. Results: TAp63 expression is downregulated in colon cancer, and microRNA-133b is a transcriptional target of TAp63. Furthermore, microRNA-133b is essential for the inhibitory effects of TAp63 on RhoA, E-cadherin and vimentin. Moreover, TAp63 inhibits cell migration and invasion through microRNA-133b. Correspondingly, the inhibitory effect of TAp63 on RhoA, E-cadherin, vimentin, migration and invasion can be blocked by the microRNA-133b inhibitor. Conclusions: TAp63 and microRNA-133b were able to suppress the metastasis of colon cancer. Both TAp63 and microRNA-133b may be potential biomarkers for diagnosis in colon cancer metastasis and may provide unique therapeutic targets for this common malignancy. PMID:24594999

  14. Solvent-mediated repair and patterning of surfaces by AFM

    SciTech Connect

    Elhadj, S; Chernov, A; De Yoreo, J

    2007-10-30

    A tip-based approach to shaping surfaces of soluble materials with nanometer-scale control is reported. The proposed method can be used, for example, to eliminate defects and inhomogeneities in surface shape, repair mechanical or laser-induced damage to surfaces, or perform 3D lithography on the length scale of an AFM tip. The phenomenon that enables smoothing and repair of surfaces is based on the transport of material from regions of high- to low-curvature within the solution meniscus formed in a solvent-containing atmosphere between the surface in question and an AFM tip scanned over the surface. Using in situ AFM measurements of the kinetics of surface remodeling on KDP (KH{sub 2}PO{sub 4}) crystals in humid air, we show that redistribution of solute material during relaxation of grooves and mounds is driven by a reduction in surface free energy as described by the Gibbs-Thomson law. We find that the perturbation from a flat interface evolves according to the diffusion equation where the effective diffusivity is determined by the product of the surface stiffness and the step kinetic coefficient. We also show that, surprisingly, if the tip is instead scanned over or kept stationary above an atomically flat area of the surface, a convex structure is formed with a diameter that is controlled by the dimensions of the meniscus, indicating that the presence of the tip and meniscus reduces the substrate chemical potential beneath that of the free surface. This allows one to create nanometer-scale 3D structures of arbitrary shape without the removal of substrate material or the use of extrinsic masks or chemical compounds. Potential applications of these tip-based phenomena are discussed.

  15. Applications of AFM for atomic manipulation and spectroscopy

    NASA Astrophysics Data System (ADS)

    Custance, Oscar

    2009-03-01

    Since the first demonstration of atom-by-atom assembly [1], atomic manipulation with scanning tunneling microscopy has yielded stunning realizations in nanoscience. A new exciting panorama has been recently opened with the possibility of manipulating atoms at surfaces using atomic force microscopy (AFM) [2-5]. In this talk, we will present two different approaches that enable patterning structures at semiconductor surfaces by manipulating individual atoms with AFM and at room temperature [2, 3]. We will discuss the physics behind each protocol through the analysis of the measured forces associated with these manipulations [3-5]. Another challenging issue in scanning probe microscopy is the ability to disclose the local chemical composition of a multi-element system at atomic level. Here, we will introduce a single-atom chemical identification method, which is based on detecting the forces between the outermost atom of the AFM tip and the atoms at a surface [6]. We demonstrate this identification procedure on a particularly challenging system, where any discrimination attempt based solely on topographic measurements would be impossible to achieve. [4pt] References: [0pt] [1] D. M. Eigler and E. K. Schweizer, Nature 344, 524 (1990); [0pt] [2] Y. Sugimoto, M. Abe, S. Hirayama, N. Oyabu, O. Custance and S. Morita, Nature Materials 4, 156 (2005); [0pt] [3] Y. Sugimoto, P. Pou, O. Custance, P. Jelinek, M. Abe, R. Perez and S. Morita, Science 322, 413 (2008); [0pt] [4] Y. Sugimoto, P. Jelinek, P. Pou, M. Abe, S. Morita, R. Perez and O. Custance, Phys. Rev. Lett. 98, 106104 (2007); [0pt] [5] M. Ternes, C. P. Lutz, C. F. Hirjibehedin, F. J. Giessibl and A. J. Heinrich, Science 319, 1066 (2008); [0pt] [6] Y. Sugimoto, P. Pou, M. Abe, P. Jelinek, R. Perez, S. Morita, and O. Custance, Nature 446, 64 (2007)

  16. The Advancing State of AF-M315E Technology

    NASA Technical Reports Server (NTRS)

    Masse, Robert; Spores, Ronald A.; McLean, Chris

    2014-01-01

    The culmination of twenty years of applied research in hydroxyl ammonium nitrate (HAN)-based monopropellants, the NASA Space Technology mission Directorate's (STMD) Green Propellant Infusion Mission (GPIM) will achieve the first on-orbit demonstration of an operational AF-M315E green propellant propulsion system by the end of 2015. Following an contextual overview of the completed flight design of the GPIM propellant storage and feed system, results of first operation of a flight-representative heavyweight 20-N engineering model thruster (to be conducted in mid-2014) are presented with performance comparisons to prior lab model (heavyweight) test articles.

  17. VirusTAP: Viral Genome-Targeted Assembly Pipeline

    PubMed Central

    Yamashita, Akifumi; Sekizuka, Tsuyoshi; Kuroda, Makoto

    2016-01-01

    Although next-generation sequencing (NGS) technology provides a comprehensive means with which to identify potential pathogens from clinical specimens, simple and user-friendly bioinformatics pipelines are expected to obtain the entire viral genome sequence, subsequently providing traceability, based on extensive molecular phylogenetic analyses. We have developed a web-based integrated NGS analysis tool for the viral genome (virus genome-targeted assembly pipeline: VirusTAP), which includes extensive sequence subtraction of host- or bacteria-related NGS reads prior to de novo assembly, leading to the prompt and accurate assembly of viral genome sequences from metagenomic NGS reads. The VirusTAP web site is at https://gph.niid.go.jp/cgi-bin/virustap/index.cgi/. PMID:26870004

  18. Spontaneous synchronized tapping to an auditory rhythm in a chimpanzee

    PubMed Central

    Hattori, Yuko; Tomonaga, Masaki; Matsuzawa, Tetsuro

    2013-01-01

    Humans actively use behavioral synchrony such as dancing and singing when they intend to make affiliative relationships. Such advanced synchronous movement occurs even unconsciously when we hear rhythmically complex music. A foundation for this tendency may be an evolutionary adaptation for group living but evolutionary origins of human synchronous activity is unclear. Here we show the first evidence that a member of our closest living relatives, a chimpanzee, spontaneously synchronizes her movement with an auditory rhythm: After a training to tap illuminated keys on an electric keyboard, one chimpanzee spontaneously aligned her tapping with the sound when she heard an isochronous distractor sound. This result indicates that sensitivity to, and tendency toward synchronous movement with an auditory rhythm exist in chimpanzees, although humans may have expanded it to unique forms of auditory and visual communication during the course of human evolution. PMID:23535698

  19. Spontaneous synchronized tapping to an auditory rhythm in a chimpanzee.

    PubMed

    Hattori, Yuko; Tomonaga, Masaki; Matsuzawa, Tetsuro

    2013-01-01

    Humans actively use behavioral synchrony such as dancing and singing when they intend to make affiliative relationships. Such advanced synchronous movement occurs even unconsciously when we hear rhythmically complex music. A foundation for this tendency may be an evolutionary adaptation for group living but evolutionary origins of human synchronous activity is unclear. Here we show the first evidence that a member of our closest living relatives, a chimpanzee, spontaneously synchronizes her movement with an auditory rhythm: After a training to tap illuminated keys on an electric keyboard, one chimpanzee spontaneously aligned her tapping with the sound when she heard an isochronous distractor sound. This result indicates that sensitivity to, and tendency toward synchronous movement with an auditory rhythm exist in chimpanzees, although humans may have expanded it to unique forms of auditory and visual communication during the course of human evolution. PMID:23535698

  20. Fouling Study of Silicon Oxide Pores Exposed to Tap Water

    SciTech Connect

    Nilsson, J.; Bourcier, W.L.; Lee, J.R.I.; Letant, S.E.; /LLNL, Livermore

    2007-07-12

    We report on the fouling of Focused Ion Beam (FIB)-fabricated silicon oxide nanopores after exposure to tap water for two weeks. Pore clogging was monitored by Scanning Electron Microscopy (SEM) on both bare silicon oxide and chemically functionalized nanopores. While fouling occurred on hydrophilic silicon oxide pore walls, the hydrophobic nature of alkane chains prevented clogging on the chemically functionalized pore walls. These results have implications for nanopore sensing platform design.

  1. Developments in signal processing and interpretation in laser tapping

    NASA Astrophysics Data System (ADS)

    Perton, M.; Neron, C.; Blouin, A.; Monchalin, J.-P.

    2013-01-01

    A novel technique, called laser-tapping, based on the thermoelastic excitation by laser like laser-ultrasonics has been previously introduced for inspecting honeycomb and foam core structures. If the top skin is delaminated or detached from the substrate, the detached layer is driven into vibration. The interpretation of the vibrations in terms of Lamb wave resonances is first discussed for a flat bottom hole configuration and then used to determine appropriate signal processing for samples such as honeycomb structures.

  2. Barometric fluctuations in wells tapping deep unconfined aquifers.

    USGS Publications Warehouse

    Weeks, E.P.

    1979-01-01

    Barometric effects on water levels in unconfined aquifers can be computed by solution of the differential equation governing the flow of gas in the unsaturated zone subject to the appropriate boundary conditions. Solutions to this equation for two sets of boundary conditions were applied to compute water level response in a well tapping the Ogallala Formation near Lubbock, Texas from simultaneous microbarograph records. -from Author

  3. Browsing TAP Services with TAPHandle and DataLink

    NASA Astrophysics Data System (ADS)

    Michel, L.; Louys, M.; Bonnarel, F.

    2014-05-01

    Here we present an update of the TAPhandle application and how it operates with other standards in the Virtual Observatory (VO): Registry, Data Access Protocols, SAMP protocol. This new version investigates and implements a new concept of links between data and services elaborated currently as a new VO capability: the DataLink protocol. More than a simple browser, TapHandle captures the of astronomical datasets and offers a clear and handy interface on top of the TAP VO infrastructure. This application helps the user to discover, sort out and select datasets of interest for the scientist. It shows for each discovered dataset a selection of tools that the user may launch to go deeper in the data exploration, like image preview, spectral model fitting, average map for a data cube, etc. Tap-Handle evolves towards more flexibility to describe data sets with associated services that can explore and transform them either with VO-aware applications but also with specific science tools developped in the astronomical community. The SAMP protocol is at work to organize the data flow between the various tools.

  4. Case Report: A case report of dry tap during ventriculostomy

    PubMed Central

    Munakomi, Sunil; Bhattarai, Binod

    2015-01-01

    Pneumocephalus following ventriculoperitoneal (VP) shunt insertion is an exceptionally rare occurrence. We report such an event after attempting ventricular puncture (ventriculostomy) for VP shunt insertion and then discuss the management of the same. Dry tap can lead to multiple attempts for ventriculostomy with the associated added risks of complications, as well as complicating the subsequent management. In addition, there is an increased risk of tension pneumocephalus, seizure and shunt failure due to a blockage by air bubbles. Our patient presented with features of raised intracranial pressure two months following craniotomy and evacuation of traumatic subdural hematoma. External ventricular puncture revealed egress of CSF under pressure. Upon attempting VP shunting for post-traumatic hydrocephalus, we experienced dry tap during ventricular puncture that complicated further management. We placed the proximal shunt in the presumed location of the foramen of Monro of ipsilateral frontal horn of lateral ventricle and did not remove the external ventricular drain. Post-operative CT scan revealed pneumoventriculi as the cause for the dry tap during ventricular puncture. Patient was managed with 100% oxygen. He showed gradual improvement and was later discharged. This case shows that variations in the procedure, including head down positioning, adequate cruciate dural incision prior to cortex puncture, and avoiding excessive egress of CSF can help to prevent such complications. PMID:27239267

  5. Case Report: A case report of dry tap during ventriculostomy.

    PubMed

    Munakomi, Sunil; Bhattarai, Binod

    2015-01-01

    Pneumocephalus following ventriculoperitoneal (VP) shunt insertion is an exceptionally rare occurrence. We report such an event after attempting ventricular puncture (ventriculostomy) for VP shunt insertion and then discuss the management of the same. Dry tap can lead to multiple attempts for ventriculostomy with the associated added risks of complications, as well as complicating the subsequent management. In addition, there is an increased risk of tension pneumocephalus, seizure and shunt failure due to a blockage by air bubbles. Our patient presented with features of raised intracranial pressure two months following craniotomy and evacuation of traumatic subdural hematoma. External ventricular puncture revealed egress of CSF under pressure. Upon attempting VP shunting for post-traumatic hydrocephalus, we experienced dry tap during ventricular puncture that complicated further management. We placed the proximal shunt in the presumed location of the foramen of Monro of ipsilateral frontal horn of lateral ventricle and did not remove the external ventricular drain. Post-operative CT scan revealed pneumoventriculi as the cause for the dry tap during ventricular puncture. Patient was managed with 100% oxygen. He showed gradual improvement and was later discharged. This case shows that variations in the procedure, including head down positioning, adequate cruciate dural incision prior to cortex puncture, and avoiding excessive egress of CSF can help to prevent such complications. PMID:27239267

  6. Channel erosion surveys along proposed TAPS route, Alaska, July 1971

    USGS Publications Warehouse

    Childers, Joseph M.

    1972-01-01

    The U.S. Geological Survey has the threefold responsibility along the proposed route of the Trans-Alaska Pipeline System (TAPS): to investigate possible hydroloqic hazards to the pipeline, to investigate possible impacts of the pipeline on water resources, and to develop a better understanding of Arctic hydrology. Because the proposed pipeline route lies within many stream channels, one of the obvious hydrologic hazards is channel erosion. It was considered a major hazard in a report by Hadley (1969) after a short reconnaissance of the proposed pipeline route and also in a national assessment of water resources by the Water Resources Council (1968). The U.S. Department of Interior has also recognized the channel erosion problems in considering the environmental impacts of TAPS and has stipulated conditions for their control (U.S. Dept. of Interior, 1972a, b). The Alyeska Pipeline Service Company (APSC), who would build and operate TAPS, has described methods for complying with the Department of Interior stipulations for channel and erosion control (APSC, 1971).

  7. Improving the Lateral Resolution of Quartz Tuning Fork-Based Sensors in Liquid by Integrating Commercial AFM Tips into the Fiber End

    PubMed Central

    Gonzalez, Laura; Martínez-Martín, David; Otero, Jorge; de Pablo, Pedro José; Puig-Vidal, Manel; Gómez-Herrero, Julio

    2015-01-01

    The use of quartz tuning fork sensors as probes for scanning probe microscopy is growing in popularity. Working in shear mode, some methods achieve a lateral resolution comparable with that obtained with standard cantilevered probes, but only in experiments conducted in air or vacuum. Here, we report a method to produce and use commercial AFM tips in electrically driven quartz tuning fork sensors operating in shear mode in a liquid environment. The process is based on attaching a standard AFM tip to the end of a fiber probe which has previously been sharpened. Only the end of the probe is immersed in the buffer solution during imaging. The lateral resolution achieved is about 6 times higher than that of the etched microfiber on its own. PMID:25594596

  8. Investigation of microwave photonic filter based on multiple longitudinal modes fiber laser source

    NASA Astrophysics Data System (ADS)

    Cao, Yuan; Li, Feng; Feng, Xinhuan; Lu, Chao; Guan, Bai-ou; Wai, P. K. A.

    2015-06-01

    We theoretically study the transfer function of a finite impulse response microwave photonic filter (FIR-MPF) system using a multi-wavelength fiber laser source by considering multiple longitudinal modes in each wavelength. The full response function with the response from longitudinal mode taps is obtained. We also discussed the influence of the longitudinal mode envelope and mode spacing on the performance of FIR-MPF. The response function of the longitudinal mode taps is fully discussed and the contribution is compared with the response of the carrier suppression factor for double sideband (DSB) modulation. The multiple longitudinal modes structure in the wavelength taps can be utilized to engineer the response of the FIR-MPF such that desirable features such as high side lode suppression ratio can be realized. The analysis provides a guideline for designing incoherent FIR-MPF systems.

  9. Raman confocal microscopy and AFM combined studies of cancerous cells treated with Paclitaxel

    NASA Astrophysics Data System (ADS)

    Derely, L.; Collart Dutilleul, P.-Y.; Michotte de Welle, Sylvain; Szabo, V.; Gergely, C.; Cuisinier, F. J. G.

    2011-03-01

    Paclitaxel interferes with the normal function of microtubule breakdown, induces apoptosis in cancer cells and sequesters free tubulin. As this drug acts also on other cell mechanisms it is important to monitor its accumulation in the cell compartments. The intracellular spreading of the drug was followed using a WITEC 300R confocal Raman microscope equipped with a CCD camera. Hence Atomic force microscopy (an MFP3D- Asylum Research AFM) in imaging and force mode was used to determine the morphological and mechanical modifications induced on living cells. These studies were performed on living epithelial MCF-7 breast cancer cells. Paclitaxel was added to cell culture media for 3, 6 and 9 hours. Among the specific paclitaxel Raman bands we selected the one at 1670 cm-1 because it is not superposed by the spectrum of the cells. Confocal Raman images are formed by monitoring this band, the NH2 and the PO4 band. Paclitaxel slightly accumulates in the nucleus forming patches. The drug is also concentrated in the vicinity of the cell membrane and in an area close to the nucleus where proteins accumulate. Our AFM images reveal that the treated cancerous MCF-7 cells keep the same size as the non treated ones, but their shape becomes more oval. Cell's elasticity is also modified: a difference of 2 kPa in the Young Modulus characterizes the treated MCF-7 mammary cancerous cell. Our observations demonstrate that paclitaxel acts not only on microtubules but accumulates also in other cell compartments (nucleus) where microtubules are absent.

  10. Viscoelasticity of gelatin surfaces probed by AFM noise analysis.

    PubMed

    Benmouna, Farida; Johannsmann, Diethelm

    2004-01-01

    The viscoelastic properties of surfaces of swollen gelatin were investigated by analyzing the Brownian motion of an atomic force microscopy (AFM) cantilever in contact with the gel surface. A micron-sized glass sphere attached to the AFM cantilever is used as the dynamic probe. When the sphere approaches the gelatin surface, there is a static repulsive force without a jump into contact. The cantilever's Brownian movement is monitored in parallel, providing access to the dynamic sphere-surface interaction as quantified by the dynamic spring constant, kappa, and the drag coefficient, xi. Gelatin is used as a model substance for a variety of other soft surfaces, where the stiffness of the gel can be varied via the solvent quality, the bloom number, and the pH. The modulus derived from the static force-distance curve is in the kPa range, consistent with the literature. However, the dynamic spring constant as derived from the Brownian motion is much larger than the static differential spring constant dF/dz. On retraction, one observes a rather strong adhesion hysteresis. The strength of the bridge (as given by the dynamic spring constant and the drag coefficient) is very small. PMID:15745019

  11. Iron oxide mineral-water interface reactions studied by AFM

    SciTech Connect

    Hawley, M.E.; Rogers, P.S.Z.

    1994-07-01

    Natural iron mineral surfaces have been examined in air by atomic force (AFM) and scanning tunneling (STM) microscopies. A number of different surface features were found to be characteristic of the native surface. Even surfaces freshly exposed by crushing larger crystals were found to have a pebbly surface texture caused by the presence of thin coatings of what might be surface precipitates. This finding is interpreted as evidence for previous exposure to water, probably through an extensive network of microfractures. Surface reactions on the goethite crystals were studied by AFM at size resolutions ranging from microns to atomic resolution before, during, and after reaction with distilled water and 0.lN HCl. Immediate and extensive surface reconfiguration occurred on contact with water. In one case, after equilibration with water for 3 days, surface reprecipitation, etching and pitting were observed. Atomic resolution images taken under water were found to be disordered. The result of surface reaction was generally to increase the surface area substantially through the extension of surface platelet arrays, present prior to reaction. This work is being done in support of the site characterization project at Yucca Mountain.

  12. Pathogen identification using peptide nanotube biosensors and impedance AFM

    NASA Astrophysics Data System (ADS)

    Maccuspie, Robert I.

    Pathogen identification at highly sensitive levels is crucial to meet urgent needs in fighting the spread of disease or detecting bioterrorism events. Toward that end, a new method for biosensing utilizing fluorescent antibody nanotubes is proposed. Fundamental studies on the self-assembly of these peptide nanotubes are performed, as are applications of aligning these nanotubes on surfaces. As biosensors, these nanotubes incorporate recognition units with antibodies at their ends and fluorescent signaling units at their sidewalls. When viral pathogens were mixed with these antibody nanotubes in solution, the nanotubes rapidly aggregated around the viruses. The size of the aggregates increased as the concentration of viruses increased, as detected by flow cytometry on the order of attomolar concentrations by changes in fluorescence and light scattering intensities. This enabled determination of the concentrations of viruses at trace levels (102 to 106 pfu/mL) within 30 minutes from the receipt of samples to the final quantitative data analysis, as demonstrated on Adenovirus, Herpes Simplex Virus, Influenza, and Vaccinia virus. As another separate approach, impedance AFM is used to study the electrical properties of individual viruses and nanoparticles used as model systems. The design, development, and implementation of the impedance AFM for an Asylum Research platform is described, as well as its application towards studying the impedance of individual nanoparticles as a model system for understanding the fundamental science of how the life cycle of a virus affects its electrical properties. In combination, these approaches fill a pressing need to quantify viruses both rapidly and sensitively.

  13. SU-8 hollow cantilevers for AFM cell adhesion studies

    NASA Astrophysics Data System (ADS)

    Martinez, Vincent; Behr, Pascal; Drechsler, Ute; Polesel-Maris, Jérôme; Potthoff, Eva; Vörös, Janos; Zambelli, Tomaso

    2016-05-01

    A novel fabrication method was established to produce flexible, transparent, and robust tipless hollow atomic force microscopy (AFM) cantilevers made entirely from SU-8. Channels of 3 μm thickness and several millimeters length were integrated into 12 μm thick and 40 μm wide cantilevers. Connected to a pressure controller, the devices showed high sealing performance with no leakage up to 6 bars. Changing the cantilever lengths from 100 μm to 500 μm among the same wafer allowed the targeting of various spring constants ranging from 0.5 to 80 N m‑1 within a single fabrication run. These hollow polymeric AFM cantilevers were operated in the optical beam deflection configuration. To demonstrate the performance of the device, single-cell force spectroscopy experiments were performed with a single probe detaching in a serial protocol more than 100 Saccharomyces cerevisiae yeast cells from plain glass and glass coated with polydopamine while measuring adhesion forces in the sub-nanoNewton range. SU-8 now offers a new alternative to conventional silicon-based hollow cantilevers with more flexibility in terms of complex geometric design and surface chemistry modification.

  14. Comparison of particle sizes determined with impactor, AFM and SEM

    NASA Astrophysics Data System (ADS)

    Gwaze, Patience; Annegarn, Harold J.; Huth, Joachim; Helas, Günter

    2007-11-01

    Particles size comparisons were made between conventional aerodynamic and mobility sizing techniques and physical geometric sizes measured by high resolution microscopes. Atmospheric particles were collected during the wet and dry seasons in the Amazonian ecosystems. Individual particles deposited on four stages of the MOUDI (Micro-Orifice Uniform Deposition Impactor) were characterised for particle volumes, projected surface diameters and morphologies with an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). AFM and SEM size distributions were verified against distributions derived from response functions of individual MOUDI stages as specified by Winklmayr et al. [Winklmayr, W., Wang, H.-C., John, W., 1990. Adaptation of the Twomey algorithm to the inversion of cascade impactor data. Aerosol Science and Technology 13, 322-331.]. Particles indicated inherent discrepancies in sizing techniques. Particle volumes were systematically lower than expected by factors of up to 3.6. Differences were attributed to loss of mass, presumably water adsorbed on particles. Losses were high and could not be accounted for by measured humidity growth factors suggesting significant losses of other volatile compounds as well, particularly on particles that were collected during the wet season. Microscopy results showed that for hygroscopic particles, microscopy sizes depend on the relative humidity history of particles before and after sampling. Changes in relative humidity significantly altered particle morphologies. Depending on when changes occur, such losses will bias not only microscopy particle sizes but also impactor mass distributions and number concentrations derived from collected particles.

  15. AFM analysis of bleaching effects on dental enamel microtopography

    NASA Astrophysics Data System (ADS)

    Pedreira de Freitas, Ana Carolina; Espejo, Luciana Cardoso; Botta, Sergio Brossi; Teixeira, Fernanda de Sa; Luz, Maria Aparecida A. Cerqueira; Garone-Netto, Narciso; Matos, Adriana Bona; Salvadori, Maria Cecilia Barbosa da Silveira

    2010-02-01

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 μm × 15 μm area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  16. Synergistic cooperation of MDM2 and E2F1 contributes to TAp73 transcriptional activity

    SciTech Connect

    Kasim, Vivi; Huang, Can; Zhang, Jing; Jia, Huizhen; Wang, Yunxia; Yang, Li; Miyagishi, Makoto; Wu, Shourong

    2014-07-04

    Highlights: • MDM2 is a novel positive regulator of TAp73 transcriptional activity. • MDM2 colocalizes together and physically interacts with E2F1. • Synergistic cooperation of MDM2 and E2F1 is crucial for TAp73 transcription. • MDM2 regulates TAp73 transcriptional activity in a p53-independent manner. - Abstract: TAp73, a structural homologue of p53, plays an important role in tumorigenesis. E2F1 had been reported as a transcriptional regulator of TAp73, however, the detailed mechanism remains to be elucidated. Here we reported that MDM2-silencing reduced the activities of the TAp73 promoters and the endogenous TAp73 expression level significantly; while MDM2 overexpression upregulated them. We further revealed that the regulation of TAp73 transcriptional activity occurs as a synergistic effect of MDM2 and E2F1, most probably through their physical interaction in the nuclei. Furthermore, we also suggested that MDM2 might be involved in DNA damage-induced TAp73 transcriptional activity. Finally, we elucidated that MDM2-silencing reduced the proliferation rate of colon carcinoma cells regardless of the p53 status. Our data show a synergistic effect of MDM2 and E2F1 on TAp73 transcriptional activity, suggesting a novel regulation pathway of TAp73.

  17. Effect of different head positions on the jaw closing point during tapping movements.

    PubMed

    Yamamoto, T; Nishigawa, K; Bando, E; Hosoki, M

    2009-01-01

    This study aimed to investigate the effects of different head positions on jaw closing points during tapping movements. The jaw movements of 20 adult volunteers were assessed using a new jaw-tracking device. All subjects had stable maximal intercuspation with their natural dentitions. The subjects were asked to seat on a dental chair with their head upright, and tapping movements were recorded for 5 s without any further instructions. After the chair was reclined to the horizontal position, tapping movements were also recorded with the head in the supine position. The location of the tapping point was defined as the jaw position which was the most closed to the maximum intercuspal position during each tapping stroke. Fifteen tapping points were obtained from the upright and supine head positions of each subject. Six-hundred tapping points were compared to evaluate the effects of different head positions. With the head upright, tapping points were relatively stable and close to the jaw position at the maximum intercuspation. However, in the supine position, tapping points varied widely and shifted forward. The average distance between the positions of the incisal point at the maximum intercuspation and at the tapping points was 0.11 mm (SD, 0.10) in the upright position and 0.30 mm (SD, 0.08) in the supine position. A Wilcoxon signed rank test showed a significant difference (P < 0.01) between these distances. We conclude that tapping points shift anteriorly in the supine position. PMID:18976269

  18. Sensing Thumb-to-Finger Taps for Symbolic Input in VR/AR Environments.

    PubMed

    Prätorius, Manuel; Burgbacher, Ulrich; Valkov, Dimitar; Hinrichs, Klaus

    2015-01-01

    Thumb-to-finger tap interaction can be employed to perform eyes-free, discrete, symbolic input in virtual and augmented reality environments. The DigiTap device is worn on the wrist to keep the hand free from any instrumentation so as not to impair tactile sense and dexterity. DigiTap senses the jerk that is caused by a tap and takes an image sequence to detect the tap location. The device can recognize taps at 12 different locations on the fingers, and at some positions, it can even distinguish between different tap strengths. The authors conducted an extended user study to evaluate users' abilities to interact with the device and perform symbolic input. PMID:26416361

  19. TAp63 is a master transcriptional regulator of lipid and glucose metabolism.

    PubMed

    Su, Xiaohua; Gi, Young Jin; Chakravarti, Deepavali; Chan, Io Long; Zhang, Aijun; Xia, Xuefeng; Tsai, Kenneth Y; Flores, Elsa R

    2012-10-01

    TAp63 prevents premature aging, suggesting a link to genes that regulate longevity. Further characterization of TAp63-/- mice revealed that these mice develop obesity, insulin resistance, and glucose intolerance similar to those seen in mice lacking two key metabolic regulators, Silent information regulator T1 (Sirt1) and AMPK. While the roles of Sirt1 and AMPK in metabolism have been well studied, their upstream regulators are not well understood. We found that TAp63 is important in regulating energy metabolism by accumulating in response to metabolic stress and transcriptionally activating Sirt1, AMPKα2, and LKB1, resulting in increased fatty acid synthesis and decreased fatty acid oxidation. Moreover, we found that TAp63 lowers blood glucose levels in response to metformin. Restoration of Sirt1, AMPKα2, and LKB1 in TAp63-/- mice rescued some of the metabolic defects of the TAp63-/- mice. Our study defines a role for TAp63 in metabolism and weight control. PMID:23040072

  20. A Novel Atomic Force Microscope with Multi-Mode Scanner

    NASA Astrophysics Data System (ADS)

    Qin, Chun; Zhang, Haijun; Xu, Rui; Han, Xu; Wang, Shuying

    2016-01-01

    A new type of atomic force microscope (AFM) with multi-mode scanner is proposed. The AFM system provides more than four scanning modes using a specially designed scanner with three tube piezoelectric ceramics and three stack piezoelectric ceramics. Sample scanning of small range with high resolution can be realized by using tube piezos, meanwhile, large range scanning can be achieved by stack piezos. Furthermore, the combination with tube piezos and stack piezos not only realizes high-resolution scanning of small samples with large- scale fluctuation structure, but also achieves small range area-selecting scanning. Corresponding experiments are carried out in terms of four different scanning modes showing that the AFM is of reliable stability, high resolution and can be widely applied in the fields of micro/nano-technology.

  1. Combined solid-state and mechanically-switched transformer tap-changer

    SciTech Connect

    Eitzmann, M.A.; Hill, A.T.

    1995-04-18

    Disclosed is an End-Turn Solid-State Switching (ETSS) transformer tap which makes use of a high-speed solid-state switching network to select either the end-turn lead or one of a number of non-isolated taps on a transformer regulating winding, and connects the selected tap to, while disconnecting the previously selected tap from, a single output conductor carrying the transformer load current. ETSS effectively changes the reference to one of the possible taps interfaced to a solid-state switching network. The same transformer regulating winding connected to ETSS can also be connected in series with a slow-speed mechanically-switched tap-changer (LTC). ETSS selects one connection point on the regulating winding while LTC operation selects the second point. A difference voltage is produced, depending on the number of turns between the ETSS selected tap and the LTC selected tap. The sign of the difference in voltage depends on whether the ETSS selected tap is higher or lower than the LTC selected tap. The difference or tap selected voltage is in series with the transformer load current. In one embodiment, the high-speed solid-state switching network uses a ``Staggered Progression of Solid-State Switches`` (SPSS) to select one of a number of non-isolated taps on a transformer regulating winding and connect the selected tap in series with the load circuit. A switching network arranged according to the method SPSS reduces the necessary total switch power rating, and steady-state losses. ETSS can accomplish modulation of the tap-selected voltage about the nominal value established by the LTC. 9 figs.

  2. The importance of correcting for variable probe-sample interactions in AFM-IR spectroscopy: AFM-IR of dried bacteria on a polyurethane film.

    PubMed

    Barlow, Daniel E; Biffinger, Justin C; Cockrell-Zugell, Allison L; Lo, Michael; Kjoller, Kevin; Cook, Debra; Lee, Woo Kyung; Pehrsson, Pehr E; Crookes-Goodson, Wendy J; Hung, Chia-Suei; Nadeau, Lloyd J; Russell, John N

    2016-08-01

    AFM-IR is a combined atomic force microscopy-infrared spectroscopy method that shows promise for nanoscale chemical characterization of biological-materials interactions. In an effort to apply this method to quantitatively probe mechanisms of microbiologically induced polyurethane degradation, we have investigated monolayer clusters of ∼200 nm thick Pseudomonas protegens Pf-5 bacteria (Pf) on a 300 nm thick polyether-polyurethane (PU) film. Here, the impact of the different biological and polymer mechanical properties on the thermomechanical AFM-IR detection mechanism was first assessed without the additional complication of polymer degradation. AFM-IR spectra of Pf and PU were compared with FTIR and showed good agreement. Local AFM-IR spectra of Pf on PU (Pf-PU) exhibited bands from both constituents, showing that AFM-IR is sensitive to chemical composition both at and below the surface. One distinct difference in local AFM-IR spectra on Pf-PU was an anomalous ∼4× increase in IR peak intensities for the probe in contact with Pf versus PU. This was attributed to differences in probe-sample interactions. In particular, significantly higher cantilever damping was observed for probe contact with PU, with a ∼10× smaller Q factor. AFM-IR chemical mapping at single wavelengths was also affected. We demonstrate ratioing of mapping data for chemical analysis as a simple method to cancel the extreme effects of the variable probe-sample interactions. PMID:27403761

  3. AFM CHARACTERIZATION OF RAMAN LASER INDUCED DAMAGE ON CDZNTECRYSTAL SURFACES

    SciTech Connect

    Teague, L.; Duff, M.

    2008-10-07

    High quality CdZnTe (or CZT) crystals have the potential for use in room temperature gamma-ray and X-ray spectrometers. Over the last decade, the methods for growing high quality CZT have improved the quality of the produced crystals however there are material features that can influence the performance of these materials as radiation detectors. The presence of structural heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), and secondary phases (SPs) can have an impact on the detector performance. There is considerable need for reliable and reproducible characterization methods for the measurement of crystal quality. With improvements in material characterization and synthesis, these crystals may become suitable for widespread use in gamma radiation detection. Characterization techniques currently utilized to test for quality and/or to predict performance of the crystal as a gamma-ray detector include infrared (IR) transmission imaging, synchrotron X-ray topography, photoluminescence spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In some cases, damage caused by characterization methods can have deleterious effects on the crystal performance. The availability of non-destructive analysis techniques is essential to validate a crystal's quality and its ability to be used for either qualitative or quantitative gamma-ray or X-ray detection. The work presented herein discusses the damage that occurs during characterization of the CZT surface by a laser during Raman spectroscopy, even at minimal laser powers. Previous Raman studies have shown that the localized annealing from tightly focused, low powered lasers results in areas of higher Te concentration on the CZT surface. This type of laser damage on the surface resulted in decreased detector performance which was most likely due to increased leakage current caused by areas of higher Te concentration. In this study

  4. AFM surface investigation of polyethylene modified by ion bombardment

    NASA Astrophysics Data System (ADS)

    Švorčík, V.; Arenholz, E.; Hnatowicz, V.; Rybka, V.; Öchsner, R.; Ryssel, H.

    1998-07-01

    Polyethylene (PE) was irradiated with 63 keV Ar + and 155 keV Xe + ions to fluences of 1 × 10 13 to 3 × 10 15 cm -2 with ion energies being chosen in order to achieve approximately the same penetration depth for both species. The PE surface morphology was examined by means of atomic force microscopy (AFM), whereas the concentration of free radicals and conjugated double bonds, both created by the ion irradiation, were determined using electron paramagnetic resonance (EPR) and UV-VIS spectroscopy, respectively. As expected, the degradation of PE was higher after irradiation with heavier Xe + ions but the changes in the PE surface morphology were more pronounced for Ar + ions. This newly observed effect can be explained by stronger compaction of the PE surface layer in the case of the Xe + irradiation, connected with a reduction of free volume available.

  5. FM-AFM crossover in vanadium oxide nanomaterials

    NASA Astrophysics Data System (ADS)

    Demishev, S. V.; Chernobrovkin, A. L.; Glushkov, V. V.; Grigorieva, A. V.; Goodilin, E. A.; Sluchanko, N. E.; Samarin, N. A.; Semeno, A. V.

    2010-01-01

    The magnetic properties of nanomaterials based on vanadium oxide (multiwall nanotubes, nanorods, and nanolayers) have been investigated in the temperature range of 1.8-220 K by high-frequency (60-GHz) EPR. A transition from a ferromagnetic temperature dependence to an antiferromagnetic temperature dependence has been observed in nanorods and nanotubes with a decrease in the temperature. The FM-AFM crossover observed near T C ˜ 110 K is accompanied by a low-temperature increase in the Curie constant by a factor of 2.7-7. The comparison of the experimental data for various VO x nanoparticles indicates that the most probable cause of the change in the type of magnetic interaction is a change in the concentration of V4+ magnetic ions.

  6. Adhesion forces between AFM tips and superficial dentin surfaces.

    PubMed

    Pelin, I M; Piednoir, A; Machon, D; Farge, P; Pirat, C; Ramos, S M M

    2012-06-15

    In this work, we study the adhesion forces between atomic force microscopy (AFM) tips and superficial dentin etched with phosphoric acid. Initially, we quantitatively analyze the effect of acid etching on the surface heterogeneity and the surface roughness, two parameters that play a key role in the adhesion phenomenon. From a statistical study of the force-distance curves, we determine the average adhesion forces on the processed substrates. Our results show that the average adhesion forces, measured in water, increase linearly with the acid exposure time. The highest values of such forces are ascribed to the high density of collagen fibers on the etched surfaces. The individual contribution of exposed collagen fibrils to the adhesion force is highlighted. We also discuss in this paper the influence of the environmental medium (water/air) in the adhesion measurements. We show that the weak forces involved require working in the aqueous medium. PMID:22472512

  7. BOREAS AFM-04 Twin Otter Aircraft Sounding Data

    NASA Technical Reports Server (NTRS)

    MacPherson, J. Ian; Desjardins, Raymond L.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-4 team used the National Research Council, Canada (NRC) Twin Otter aircraft to make sounding measurements through the boundary layer. These measurements included concentrations of carbon dioxide and ozone, atmospheric pressure, dry bulb temperature, potential temperature, dewpoint temperature, calculated mixing ratio, and wind speed and direction. Aircraft position, heading, and altitude were also recorded. Data were collected at both the Northern Study Area (NSA) and the Southern Study Area (SSA) in 1994 and 1996. These data are stored in tabular ASCII files. The Twin Otter aircraft sounding data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files also are available on a CD-ROM (see document number 20010000884).

  8. AFM of self-assembled lambda DNA-histone networks.

    PubMed

    Liu, YuYing; Guthold, Martin; Snyder, Matthew J; Lu, HongFeng

    2015-10-01

    Atomic force microscopy (AFM) was used to investigate the self-assembly behavior of λ-DNA and histones at varying histone:DNA ratios. Without histones and at the lowest histone:DNA ratio (less than one histone per 1000 base pairs of DNA), the DNA appeared as individual (uncomplexed), double-stranded DNA molecules. At increasing histone concentrations (one histone per 500, 250 and 167 base pairs of DNA), the DNA molecules started to form extensive polygonal networks of mostly pentagons and hexagons. The observed networks might be one of the naturally occurring, stable DNA-histone structures. The condensing effects of the divalent cations Mg(2+) and Ca(2+) on the DNA-histone complexes were also investigated. The networks persisted at high Mg(2+) concentration (20mM) and the highest histone concentration. At high Ca(2+) concentration and the highest histone concentration, the polygonal network disappeared and, instead, individual, tightly condensed aggregates were formed. PMID:26141439

  9. Mechanical Characterization of Photo-crosslinkable Hydrogels with AFM

    NASA Astrophysics Data System (ADS)

    McKenna, Alyssa; Byun, Myunghwan; Hayward, Ryan; Aidala, Katherine

    2012-02-01

    Stimuli-responsive hydrogel films formed from photo-crosslinkable polymers are versatile materials for controlled drug delivery devices, three-dimensional micro-assemblies, and components in microfluidic systems. For such applications, it is important to understand both the mechanical properties and the dynamics responses of these materials. We describe the use of atomic force microscope (AFM) based indentation experiments to characterize the properties of poly(N-isopropylacrylamide) copolymer films, crosslinked by activation of pendent benzophenone units using ultraviolet light. In particular, we study how the elastic modulus of the material, determined using the Johnson, Kendall, and Roberts model, depends on UV dose, and simultaneously investigate stress relaxation in these materials in the context of viscoelastic and poroelastic relaxation models.

  10. Loss tangent imaging: Theory and simulations of repulsive-mode tapping atomic force microscopy

    SciTech Connect

    Proksch, Roger; Yablon, Dalia G.

    2012-02-13

    An expression for loss tangent measurement of a surface in amplitude modulation atomic force microscopy is derived using only the cantilever phase and the normalized cantilever amplitude. This provides a direct measurement of substrate compositional information that only requires tuning of the cantilever resonance to provide quantitative information. Furthermore, the loss tangent expression incorporates both the lost and stored energy into one term that represents a fundamental interpretation of the phase signal in amplitude modulation imaging. Numerical solutions of a cantilever tip interacting with a simple Voigt modeled surface agree with the derived loss tangent to within a few percent.

  11. Recent advances in exchange bias of layered magnetic FM/AFM systems

    NASA Astrophysics Data System (ADS)

    Liu, ZhongYuan

    2013-01-01

    The exchange bias (EB) has been investigated in magnetic materials with the ferromagnetic (FM)/antiferromagnetic (AFM) contacting interfaces for more than half a century. To date, the significant progress has been made in the layered magnetic FM/AFM thin film systems. EB mechanisms have shown substantive research advances. Here some of the new advances are introduced and discussed with the emphasis on the influence of AFM layer, the interlayer EB coupling across nonmagnetic spacer, and the interlayer coupling across AFM layer, as well as EB related to multiferrioc materials and electrical control.

  12. Tapped granular column dynamics: simulations, experiments and modeling

    NASA Astrophysics Data System (ADS)

    Rosato, A. D.; Zuo, L.; Blackmore, D.; Wu, H.; Horntrop, D. J.; Parker, D. J.; Windows-Yule, C.

    2016-07-01

    This paper communicates the results of a synergistic investigation that initiates our long term research goal of developing a continuum model capable of predicting a variety of granular flows. We consider an ostensibly simple system consisting of a column of inelastic spheres subjected to discrete taps in the form of half sine wave pulses of amplitude a/ d and period τ . A three-pronged approach is used, consisting of discrete element simulations based on linear loading-unloading contacts, experimental validation, and preliminary comparisons with our continuum model in the form of an integro-partial differential equation.

  13. Belief propagation vs. TAP for decoding corrupted messages

    NASA Astrophysics Data System (ADS)

    Kabashima, Y.; Saad, D.

    1998-12-01

    We employ two different methods, based on belief propagation and TAP, for decoding corrupted messages encoded by employing Sourlas's method, where the code word comprises products of K bits selected randomly from the original message. We show that the equations obtained by the two approaches are similar and provide the same solution as the one obtained by the replica approach in some cases (K = 2). However, we also show that for K >= 3 and unbiased messages the iterative solution is sensitive to the initial conditions and is likely to provide erroneous solutions; and that it is generally beneficial to use Nishimori's temperature, especially in the case of biased messages.

  14. A continuously tunable multi-tap complex-coefficient microwave photonic filter based on a tilted fiber Bragg grating.

    PubMed

    Shahoei, Hiva; Yao, Jianping

    2013-03-25

    The coupling coefficients of the cladding-mode resonances of a tilted fiber Bragg grating (TFBG) are linearly increasing or decreasing in different wavelength regions. Based on the Kramers-Kronig relations, when the coupling coefficients are linearly increasing, the phase shifts are linearly increasing correspondingly. This feature is employed, for the first time, for the implementation of a multi-tap continuously tunable microwave photonic filter with complex coefficients by using a TFBG. By locating the optical carriers of single-sideband-modulated signals at the cladding-mode resonances of the TFBG which has linearly increasing depths, linearly increasing phase shifts are introduced to the optical carriers. By beating the optical carriers with the single sidebands, the phase shifts are translated to the microwave signals, and thus complex coefficients with the required linearly increasing phase shifts are generated. The tunability of the complex coefficients is realized by optically pumping the TFBG which is written in an erbium/ytterbium (Er/Yb) co-doped fiber. A proof-of-concept experiment is performed; a three- and four-tap filter with a frequency tunable range of 150 and 120 MHz, respectively, are demonstrated. PMID:23546134

  15. PREFACE: NC-AFM 2005: Proceedings of the 8th International Conference on Non-Contact Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Reichling, M.; Mikosch, W.

    2006-04-01

    formation allow the highly resolved measurement of a number of physical properties far beyond the determination of surface topography. The development of techniques allowing atomic resolution dynamic mode imaging in liquids pushes the door open for an atomic precision analysis of biological samples under physiological conditions. In each of these fields, the conference demonstrated cutting-edge results and also provided perspectives for the next steps on the roadmap of NC-AFM towards the development of its full extent. The conference in Bad Essen was made possible by the continuous dedication of the local management and we are most grateful to Frauke Riemann, Joachim Fontaine and the members of the supporting team for the smooth organization. We gratefully appreciate the financial support of the exhibitors, namely Anfatec, HALCYONICS, JEOL, LOT-Oriel, NanoMagnetics, NT-MDT, Omicron, Schaefer Technology, SURFACE, UNISOKU and the local sponsors which enabled us to provide free participation at the conference for ten promising young researchers who had submitted excellent contributions. It was a great pleasure for us to continue our most successful collaboration with Nanotechnology as our partner for the proceedings publication and we would like to thank Ian Forbes and the publishing team for the professional handling of the peer review and all production matters.

  16. Tap-Hole Life Cycle Design Criteria: A Case Study Based on Silicomanganese Production

    NASA Astrophysics Data System (ADS)

    Steenkamp, J. D.; Sutherland, J. J.; Hayman, D. A.; Muller, J.

    2016-06-01

    Managing the tapping of furnaces is a challenge to most furnace operators. As a hole is made in the refractory lining and re-filled with clay, several times a day, the tap-hole is one of the weak spots in the refractory lining. Tap-hole failures are high-risk events, and steps should be taken to minimize the risks. Designing for the life-cycle of the tap-hole is proposed and discussed as a way of minimizing the risks associated with tap-hole failure. Design criteria are proposed not only for a total reline and normal operation but also for emergency conditions, as well as maintenance, and repair of the tap-hole. The criteria are discussed in the context of silicomanganese production in South Africa.

  17. Tap-Hole Life Cycle Design Criteria: A Case Study Based on Silicomanganese Production

    NASA Astrophysics Data System (ADS)

    Steenkamp, J. D.; Sutherland, J. J.; Hayman, D. A.; Muller, J.

    2016-03-01

    Managing the tapping of furnaces is a challenge to most furnace operators. As a hole is made in the refractory lining and re-filled with clay, several times a day, the tap-hole is one of the weak spots in the refractory lining. Tap-hole failures are high-risk events, and steps should be taken to minimize the risks. Designing for the life-cycle of the tap-hole is proposed and discussed as a way of minimizing the risks associated with tap-hole failure. Design criteria are proposed not only for a total reline and normal operation but also for emergency conditions, as well as maintenance, and repair of the tap-hole. The criteria are discussed in the context of silicomanganese production in South Africa.

  18. Accessing planetary plasma datasets via the TAP and PDAP protocols

    NASA Astrophysics Data System (ADS)

    Bourrel, N.; Cecconi, B.; Le Sidaner, P.; Érard, S.; Gangloff, M.; Jacquey, C.; Berthier, J.; Pallier, E.; Topf, F.

    2012-09-01

    There are many challenges to achieving interoperability and data sharing across heterogeneous systems. Systems and data are implemented and stored across multiple platforms and specifications. This has created rigid point-topoint integrations. To allow the interoperability of data discovery when querying planetary science data centers, the needs are to have common standards and specifications to search and retrieve data from the disparate sources provides. From a data producer perspective, they are provided with a common construct on how to expose their data, without having to compromise their internal implementation, that users and systems can easily discover, search, and consume. TAP (Table Access Protocol) and PDAP (Planetary Data Access Protocol) are protocols to access, distributed and retrieve planetary data. They can permit to provide an interoperable and flexible environment to search, aggregate and retrieve data. We will present the prototype of interoperable system planetary plasma datasets based in the Planetary Science Resource Data Model designed by EuroPlaNet IDIS (Integrated and Distributed Information Service) via the TAP and PDAP protocols.

  19. Quality assessment of Romanian bottled mineral water and tap water.

    PubMed

    M Carstea, Elfrida; Levei, Erika A; Hoaghia, Maria-Alexandra; Savastru, Roxana

    2016-09-01

    This study reports the evaluation of bottled mineral water characteristics using fluorescence spectroscopy (synchronous fluorescence scans and emission spectra) and physico-chemical analyses. Samples from 14 still mineral water brands were compared to 11 tap waters collected from two Romanian cities. Correlation and factor analyses were undertaken to understand the relationships between the individual components. The concentration of major and minor ions showed great variation between the bottled mineral water samples highlighting the diversity of the water intakes, while in the case of tap water the chemical composition was relatively similar for samples collected in the same city. Fluorescence data showed that the mineral water contained low quantities of organic matter. The humic fraction was dominant in all samples, while the microbial fraction was low in most samples. Synchronous fluorescence scans provided more information, regarding the composition of organic matter, compared to emission spectra. The study evidenced the correlation between fluorescence parameters and major elements and highlighted the potential of using fluorescence for qualitative evaluation of the bottled mineral water quality, as a screening method before undertaking complex analyses. PMID:27526046

  20. Endosymbionts of Acanthamoeba Isolated from Domestic Tap Water in Korea

    PubMed Central

    Choi, Seon Hee; Cho, Min Kyoung; Ahn, Soon Cheol; Lee, Ji Eun; Lee, Jong Soo; Kim, Dong-Hee; Xuan, Ying-Hua; Hong, Yeon Chul; Kong, Hyun Hee; Chung, Dong Il

    2009-01-01

    In a previous study, we reported our discovery of Acanthamoeba contamination in domestic tap water; in that study, we determined that some Acanthamoeba strains harbor endosymbiotic bacteria, via our molecular characterization by mitochondrial DNA restriction fragment length polymorphism (Mt DNA RFLP). Five (29.4%) among 17 Acanthamoeba isolates contained endosymbionts in their cytoplasm, as demonstrated via orcein staining. In order to estimate their pathogenicity, we conducted a genetic characterization of the endosymbionts in Acanthamoeba isolated from domestic tap water via 16S rDNA sequencing. The endosymbionts of Acanthamoeba sp. KA/WP3 and KA/WP4 evidenced the highest level of similarity, at 97% of the recently published 16S rDNA sequence of the bacterium, Candidatus Amoebophilus asiaticus. The endosymbionts of Acanthamoeba sp. KA/WP8 and KA/WP12 shared a 97% sequence similarity with each other, and were also highly similar to Candidatus Odyssella thessalonicensis, a member of the α-proteobacteria. The endosymbiont of Acanthamoeba sp. KA/WP9 exhibits a high degree of similarity (85-95%) with genus Methylophilus, which is not yet known to harbor any endosymbionts. This is the first report, to the best of our knowledge, to show that Methylophilus spp. can live in the cytoplasm of Acanthamoeba. PMID:19967080

  1. Bimolecular affinity purification: a variation of TAP with multiple applications.

    PubMed

    Starokadomskyy, Petro; Burstein, Ezra

    2014-01-01

    The identification of true interacting partners of any given bait can be plagued by the nonspecific purification of irrelevant proteins. To avoid this problem, Tandem Affinity Purification (TAP) is a widely used procedure in molecular biology as this reduces the chance of nonspecific proteins being present in the final preparation. In this approach, two different affinity tags are fused to the protein bait. Herein, we review in detail a variation on the TAP procedure that we have previously developed, where the affinity moieties are placed on two different proteins that form a complex in vivo. This variation, which we refer to as Bimolecular Affinity Purification (BAP), is suited for the identification of specific molecular complexes marked by the presence of two known proteins. We have utilized BAP for characterization of molecular complexes and evaluation of proteins interaction. Another application of BAP is the isolation of ubiquitin-like proteins (UBL)-modified fractions of a given protein and characterization of the lysine-acceptor site and structure of UBL-chains. PMID:24943324

  2. Experimental studies on intake headloss of a blasted lake tap

    NASA Astrophysics Data System (ADS)

    Yang, James; Billstein, Mats; Engström, Fredrik; Strand, Rikard

    2014-03-01

    In existing reservoirs, construction of an intake is sometimes achieved by so-called lake tapping, a submerged tunnel piercing by blasting out the rock plug at the intake. The blasting process involves phases of rock, water, air and gas released from the explosive charge; the resulting entrance profile often differs from design assumptions. The intake headloss is a factor of concern for power generation. For a vertical intake formed by lake tapping, experiments have been carried out in a 1:30 physical model to examine the effect of entrance shapes on intake headlosses. The purpose is that, if there is potential to reduce the headlosses, the originally blasted intake shape would be modified. In the model, five alternative shapes are evaluated. The test results show that to enlarge the vertical shaft area is the most effective way to reduce the intake headloss; to further blast out a narrow channel upstream does not give much effect. Bearing in mind the risk of free-surface vortex at the intake, the influence of the intake modifications on vortex is also checked.

  3. A prototype tap test imaging system: Initial field test results

    NASA Astrophysics Data System (ADS)

    Peters, J. J.; Barnard, D. J.; Hudelson, N. A.; Simpson, T. S.; Hsu, D. K.

    2000-05-01

    This paper describes a simple, field-worthy tap test imaging system that gives quantitative information about the size, shape, and severity of defects and damages. The system consists of an accelerometer, electronic circuits for conditioning the signal and measuring the impact duration, a laptop PC and data acquisition and processing software. The images are generated manually by tapping on a grid printed on a plastic sheet laid over the part's surface. A mechanized scanner is currently under development. The prototype has produced images for a variety of aircraft composite and metal honeycomb structures containing flaws, damages, and repairs. Images of the local contact stiffness, deduced from the impact duration using a spring model, revealed quantitatively the stiffness reduction due to flaws and damages, as well as the stiffness enhancement due to substructures. The system has been field tested on commercial and military aircraft as well as rotor blades and engine decks on helicopters. Field test results will be shown and the operation of the system will be demonstrated.—This material is based upon work supported by the Federal Aviation Administration under Contract #DTFA03-98-D-00008, Delivery Order No. IA016 and performed at Iowa State University's Center for NDE as part of the Center for Aviation Systems Reliability program.

  4. The EPN-TAP protocol for the Planetary Science Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Erard, S.; Cecconi, B.; Le Sidaner, P.; Berthier, J.; Henry, F.; Molinaro, M.; Giardino, M.; Bourrel, N.; André, N.; Gangloff, M.; Jacquey, C.; Topf, F.

    2014-11-01

    A Data Access Protocol has been set up to search and retrieve Planetary Science data in general. This protocol will allow the user to select a subset of data from an archive in a standard way, based on the IVOA Table Access Protocol (TAP). The TAP mechanism is completed by an underlying Data Model and reference dictionaries. This paper describes the principle of the EPN-TAP protocol and interfaces, underlines the choices that have been made, and discusses possible evolutions.

  5. BOREAS AFM-12 1-km AVHRR Seasonal Land Cover Classification

    NASA Technical Reports Server (NTRS)

    Steyaert, Lou; Hall, Forrest G.; Newcomer, Jeffrey A. (Editor); Knapp, David E. (Editor); Loveland, Thomas R.; Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-12 team's efforts focused on regional scale Surface Vegetation and Atmosphere (SVAT) modeling to improve parameterization of the heterogeneous BOREAS landscape for use in larger scale Global Circulation Models (GCMs). This regional land cover data set was developed as part of a multitemporal one-kilometer Advanced Very High Resolution Radiometer (AVHRR) land cover analysis approach that was used as the basis for regional land cover mapping, fire disturbance-regeneration, and multiresolution land cover scaling studies in the boreal forest ecosystem of central Canada. This land cover classification was derived by using regional field observations from ground and low-level aircraft transits to analyze spectral-temporal clusters that were derived from an unsupervised cluster analysis of monthly Normalized Difference Vegetation Index (NDVI) image composites (April-September 1992). This regional data set was developed for use by BOREAS investigators, especially those involved in simulation modeling, remote sensing algorithm development, and aircraft flux studies. Based on regional field data verification, this multitemporal one-kilometer AVHRR land cover mapping approach was effective in characterizing the biome-level land cover structure, embedded spatially heterogeneous landscape patterns, and other types of key land cover information of interest to BOREAS modelers.The land cover mosaics in this classification include: (1) wet conifer mosaic (low, medium, and high tree stand density), (2) mixed coniferous-deciduous forest (80% coniferous, codominant, and 80% deciduous), (3) recent visible bum, vegetation regeneration, or rock outcrops-bare ground-sparsely vegetated slow regeneration bum (four classes), (4) open water and grassland marshes, and (5) general agricultural land use/ grasslands (three classes). This land cover mapping approach did not detect small subpixel-scale landscape

  6. State estimation of voltage and phase-shift transformer tap settings

    SciTech Connect

    Teixeira, P.A.; Brammer, S.R.; Rutz, W.L. ); Merritt, W.C.; Salmonsen, J.L. )

    1992-08-01

    Traditionally, state estimation algorithms have treated each transformer tap setting (voltage transformer turns ratio or phase-shift transformer angle) as a fixed parameter of the network, even though the real-time measurement may be in error or non-existent. In this paper, a new transformer tap estimation technique is presented which incorporates the function directly into the state estimation algorithm. The procedure provides for turns ratio and phase angle measurements and treats each transformer tap setting as an independent state variable. Test results for an actual 300-bus network demonstrate the tap estimation capability.

  7. Tap water nasal irrigation in adults with seasonal allergic rhinitis: a randomized double-blind study.

    PubMed

    Xiong, Min; Fu, Xiaoyan; Deng, Wenting; Lai, Huangwen; Yang, Chuanhong

    2014-06-01

    Saline nasal irrigation is effective in the treatment of seasonal allergic rhinitis, and sodium chloride itself has no antiallergic effects. The mechanism of saline nasal irrigation depends mainly on washing away allergens and inflammatory mediators induced by allergic reactions. Tap water has the same washing effects as saline. In this study, it was investigated if tap water nasal irrigation was effective in the treatment of seasonal allergic rhinitis. Sixty-four patients diagnosed with seasonal allergic rhinitis were enrolled. Patients were randomized to tap water nasal irrigation group and non-tap water nasal irrigation group for treatment. Patients of both groups were treated with desloratadine. Treatment outcomes were measured using allergic rhinitis Quality of Life (QoL) survey was completed at baseline and after 3 weeks of therapy. There were statistically significant differences in QoL scores between tap water nasal irrigation group and non-tap water nasal irrigation group. The tap water nasal irrigation group had better QoL scores than the non-tap water nasal irrigation group. Tap water nasal irrigation can be a valuable adjuvant therapy for patients with seasonal allergic rhinitis. PMID:24091560

  8. Heat treatment-induced functional and structural aspects of Mus musculus TAp63γ

    NASA Astrophysics Data System (ADS)

    Xu, Ya; Wang, Jing-Zhang; Li, Jun-Song; Huang, Xin-He; Xing, Zhi-Hua; Du, Lin-Fang

    2011-06-01

    TAp63γ plays as an important tumor suppressor gene protecting from cancer development, especially in p53-deficient cancer cells under stresses. Here, we investigated the effects of heat treatment on the functional and structural stabilities of TAp63γ by means of the electrophoretic mobility shift assay, intrinsic tryptophan fluorescence, exogenous ANS fluorescence, and CD spectroscopies. The electrophoretic mobility shift assay result showed that the DNA binding activity of GST-TAp63γ decreased above 55 °C. The intrinsic fluorescence spectra indicated an increase of the hydrophobicity and a decrease of the polarity in the microenvironments around the tyrosine and tryptophan residues. The ANS fluorescence spectra suggested that the hydrophobic pockets in TAp63γ gradually unfolded below 50 °C. The above results indicated that TAp63γ partially unfolded at 55 °C, while the CD result showed that TAp63γ still processed a pronounced secondary structure at the same temperature, suggesting that heat treatment possibly induced the molten globule state of TAp63γ, which was an intermediate state between the native and denatured protein. Taken together, TAp63γ is a relatively unstable protein, but it has higher activity than p53 at about 50 °C. The presented work also implies that TAp63γ may play an important role in stressed microenvironments especially when p53 is deficient.

  9. Tap or bottled water: drinking preferences among urban minority children and adolescents.

    PubMed

    Huerta-Saenz, Lina; Irigoyen, Matilde; Benavides, Jorge; Mendoza, Maria

    2012-02-01

    The last decade has seen an increasing trend in consumer preference of bottled water over tap water. Little is known what type of water children and adolescents prefer for drinking and what their parents think of their community tap water. The study objective was to assess drinking water preferences, perceptions of the qualities of tap water and bottled water, and fluoride knowledge in an urban pediatric population. We conducted an anonymous survey of a convenience sample of caretakers of children and adolescents at an urban clinic regarding their preferences for tap or bottled water, their perceptions of the quality of tap and bottled water and their knowledge of fluoride. Of the 208 participants (79% African American, 9% Latino), 59% drank tap water, 80% bottled water. Only 17% drank tap water exclusively, 38% drank bottled water exclusively, 42% drank both. We found no significant differences in water preferences across age groups, from infancy to adulthood, or among ethnic groups. Ratings for taste, clarity, purity and safety were significantly higher for bottled water than tap water (P < 0.001). Only 24% were aware of fluoride in drinking water. We conclude bottled water was preferred over tap water in an urban minority pediatric population. Perceptions of the qualities of water seemed to drive drinking preferences. Public health strategies are needed to increase public awareness of the impact of bottled water consumption on oral health, household budgets and the environment. PMID:21643824

  10. Synchronized tapping facilitates learning sound sequences as indexed by the P300.

    PubMed

    Kamiyama, Keiko S; Okanoya, Kazuo

    2014-01-01

    The purpose of the present study was to determine whether and how single finger tapping in synchrony with sound sequences contributed to the auditory processing of them. The participants learned two unfamiliar sound sequences via different methods. In the tapping condition, they learned an auditory sequence while they tapped in synchrony with each sound onset. In the no tapping condition, they learned another sequence while they kept pressing a key until the sequence ended. After these learning sessions, we presented the two melodies again and recorded event-related potentials (ERPs). During the ERP recordings, 10% of the tones within each melody deviated from the original tones. An analysis of the grand average ERPs showed that deviant stimuli elicited a significant P300 in the tapping but not in the no-tapping condition. In addition, the significance of the P300 effect in the tapping condition increased as the participants showed highly synchronized tapping behavior during the learning sessions. These results indicated that single finger tapping promoted the conscious detection and evaluation of deviants within the learned sequences. The effect was related to individuals' musical ability to coordinate their finger movements along with external auditory events. PMID:25400564

  11. Nano-Wilhelmy investigation of dynamic wetting properties of AFM tips through tip-nanobubble interaction.

    PubMed

    Wang, Yuliang; Wang, Huimin; Bi, Shusheng; Guo, Bin

    2016-01-01

    The dynamic wetting properties of atomic force microscopy (AFM) tips are of much concern in many AFM-related measurement, fabrication, and manipulation applications. In this study, the wetting properties of silicon and silicon nitride AFM tips are investigated through dynamic contact angle measurement using a nano-Wilhelmy balance based method. This is done by capillary force measurement during extension and retraction motion of AFM tips relative to interfacial nanobubbles. The working principle of the proposed method and mathematic models for dynamic contact angle measurement are presented. Geometric models of AFM tips were constructed using scanning electronic microscopy (SEM) images taken from different view directions. The detailed process of tip-nanobubble interaction was investigated using force-distance curves of AFM on nanobubbles. Several parameters including nanobubble height, adhesion and capillary force between tip and nanobubbles are extracted. The variation of these parameters was studied over nanobubble surfaces. The dynamic contact angles of the AFM tips were calculated from the capillary force measurements. The proposed method provides direct measurement of dynamic contact angles for AFM tips and can also be taken as a general approach for nanoscale dynamic wetting property investigation. PMID:27452115

  12. Nano-Wilhelmy investigation of dynamic wetting properties of AFM tips through tip-nanobubble interaction

    PubMed Central

    Wang, Yuliang; Wang, Huimin; Bi, Shusheng; Guo, Bin

    2016-01-01

    The dynamic wetting properties of atomic force microscopy (AFM) tips are of much concern in many AFM-related measurement, fabrication, and manipulation applications. In this study, the wetting properties of silicon and silicon nitride AFM tips are investigated through dynamic contact angle measurement using a nano-Wilhelmy balance based method. This is done by capillary force measurement during extension and retraction motion of AFM tips relative to interfacial nanobubbles. The working principle of the proposed method and mathematic models for dynamic contact angle measurement are presented. Geometric models of AFM tips were constructed using scanning electronic microscopy (SEM) images taken from different view directions. The detailed process of tip-nanobubble interaction was investigated using force-distance curves of AFM on nanobubbles. Several parameters including nanobubble height, adhesion and capillary force between tip and nanobubbles are extracted. The variation of these parameters was studied over nanobubble surfaces. The dynamic contact angles of the AFM tips were calculated from the capillary force measurements. The proposed method provides direct measurement of dynamic contact angles for AFM tips and can also be taken as a general approach for nanoscale dynamic wetting property investigation. PMID:27452115

  13. Beyond topography - enhanced imaging of cometary dust with the MIDAS AFM

    NASA Astrophysics Data System (ADS)

    Bentley, M. S.; Torkar, K.; Jeszenszky, H.; Romstedt, J.

    2013-09-01

    The MIDAS atomic force microscope (AFM) onboard the Rosetta spacecraft is primarily designed to return the 3D shape and structure of cometary dust particles collected at comet 67P/Churyumov-Gerasimenko [1]. Commercial AFMs have, however, been further developed to measure many other sample properties. The possibilities to make such measurements with MIDAS are explored here.

  14. Nano-Wilhelmy investigation of dynamic wetting properties of AFM tips through tip-nanobubble interaction

    NASA Astrophysics Data System (ADS)

    Wang, Yuliang; Wang, Huimin; Bi, Shusheng; Guo, Bin

    2016-07-01

    The dynamic wetting properties of atomic force microscopy (AFM) tips are of much concern in many AFM-related measurement, fabrication, and manipulation applications. In this study, the wetting properties of silicon and silicon nitride AFM tips are investigated through dynamic contact angle measurement using a nano-Wilhelmy balance based method. This is done by capillary force measurement during extension and retraction motion of AFM tips relative to interfacial nanobubbles. The working principle of the proposed method and mathematic models for dynamic contact angle measurement are presented. Geometric models of AFM tips were constructed using scanning electronic microscopy (SEM) images taken from different view directions. The detailed process of tip-nanobubble interaction was investigated using force-distance curves of AFM on nanobubbles. Several parameters including nanobubble height, adhesion and capillary force between tip and nanobubbles are extracted. The variation of these parameters was studied over nanobubble surfaces. The dynamic contact angles of the AFM tips were calculated from the capillary force measurements. The proposed method provides direct measurement of dynamic contact angles for AFM tips and can also be taken as a general approach for nanoscale dynamic wetting property investigation.

  15. Assessment of metal concentrations in tap-water - from source to the tap: a case study from Szczecin, Poland

    NASA Astrophysics Data System (ADS)

    Górski, Józef; Siepak, Marcin

    2014-03-01

    The concentrations of Al, As, Cd, Cu, Pb, Zn, Ni, Fe and Mn were determined in June 2010 for 100 tap-water samples, collected directly at consumers in the older part of the city of Szczecin (Poland). Increased concentrations of metals were thus detected. This concerns mainly Fe (19% of samples showed concentrations above drinking-water quality standards) and Pb (5%). In some samples, the maximum admissible concentration levels for Mn, Cu and Ni were also exceeded. This was not the case for Al, despite the use of aluminium compounds during water treatment; the Al concentrations in treated water were, however, significantly higher than in raw water. It was also found that (1) the corrosive properties of water (low alkalinity and increased concentration of sulphates), (2) the water-treatment processes causing a decrease of the pH and an increase of the CO2, and (3) transport of the treated water over long distances (30 km) provide favourable conditions for the leaching of metals from water-pipe networks. The type of material used in domestic plumbing and the content of Ce, Fe, Mn, Ni and Cd in the tap-water at consumers show a correlation. The high content of Pb is mainly a result of lead pipes connecting the network to the buildings

  16. BOREAS AFM-2 Wyoming King Air 1994 Aircraft Sounding Data

    NASA Technical Reports Server (NTRS)

    Kelly, Robert D.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The BOREAS AFM-2 team used the University of Wyoming King Air aircraft during IFCs 1, 2, and 3 in 1994 to collected pass-by-pass fluxes (and many other statistics) for the large number of level (constant altitude), straight-line passes used in a variety of flight patterns over the SSA and NSA and areas along the transect between these study areas. The data described here form a second set, namely soundings that were incorporated into nearly every research flight by the King Air in 1994. These soundings generally went from near the surface to above the inversion layer. Most were flown immediately after takeoff or immediately after finishing the last flux pattern of that particular day's flights. The parameters that were measured include wind direction, wind speed, west wind component (u), south wind component (v), static pressure, air dry bulb temperature, potential temperature, dewpoint, temperature, water vapor mixing ratio, and CO2 concentration. Data on the aircraft's location, attitude, and altitude during data collection are also provided. These data are stored in tabular ASCH files. The data files are available on a CD-ROM (see document number 20010000884) or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  17. BOREAS AFM-03-NCAR Electra 1994 Aircraft Sounding Data

    NASA Technical Reports Server (NTRS)

    Lenschow, Donald H.; Oncley, Steven P.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-3 team used the National Center for Atmospheric Research's (NCAR) Electra aircraft to make sounding measurements to study the planetary boundary layer using in situ and remote-sensing measurements. Measurements were made of wind speed and direction, air pressure and temperature, potential temperature, dewpoint, mixing ratio of H, O, CO, concentration, and ozone concentration. Twenty-five research missions were flown over the Northern Study Area (NSA), Southern Study Area (SSA), and the transect during BOREAS Intensive Field Campaigns (IFCs) 1, 2, and 3 during 1994. All missions had from four to ten soundings through the top of the planetary boundary layer. This sounding data set contains all of the in situ vertical profiles through the boundary layer top that were made (with the exception of 'porpoise' maneuvers). Data were recorded in one-second time intervals. These data are stored in tabular ASCII files. The NCAR Electra 1994 aircraft sounding data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  18. AFM-based force microsensor for a microrobot

    NASA Astrophysics Data System (ADS)

    Fatikow, Sergej; Fahlbusch, Stephan

    2001-10-01

    Microrobots are the result of increasing research activities at the border between microsystem technology and robotics. Today already, robots with dimensions of a few cubic- centimeters can be developed. Like conventional robots, microrobots represent a complex system that usually contains several different types of actuators and sensors. The measurement of gripping forces is the most important sensor application in micromanipulation besides visual servoing to protect the parts from too high surface pressures and thereby damage during the assembly process. Very small forces in the range of 200 (mu) N down to 0.1 (mu) N or even less have to be sensed. Thus, the aim of our current research activities is the development of a high-resolution integrated force microsensor for measuring gripping forces in a microhandling robot. On the one hand, the sensor should be a device for teleoperated manipulation tasks in a flexible microhandling station. On the other hand, typical microhandling operations should to a large extend be automated with the aid of computer-based signal processing of sensor information. The user should be provided with an interface for teleoperated manipulation and an interface for partially automated manipulation of microobjects. In this paper, a concept for the measurement of gripping forces in microrobotics using piezoresistive AFM (atomic force microscope) cantilevers is introduced. Further on, the concept of a microrobot-based SEM station and its applications are presented.

  19. AFM Investigation of Liquid-Filled Polymer Microcapsules Elasticity.

    PubMed

    Sarrazin, Baptiste; Tsapis, Nicolas; Mousnier, Ludivine; Taulier, Nicolas; Urbach, Wladimir; Guenoun, Patrick

    2016-05-10

    Elasticity of polymer microcapsules (MCs) filled with a liquid fluorinated core is studied by atomic force microscopy (AFM). Accurately characterized spherical tips are employed to obtain the Young's moduli of MCs having four different shell thicknesses. We show that those moduli are effective ones because the samples are composites. The strong decrease of the effective MC elasticity (from 3.0 to 0.1 GPa) as the shell thickness decreases (from 200 to 10 nm) is analyzed using a novel numerical approach. This model describes the evolution of the elasticity of a coated half-space according to the contact radius, the thickness of the film, and the elastic moduli of bulk materials. This numerical model is consistent with the experimental data and allows simulating the elastic behavior of MCs at high frequencies (5 MHz). While the quasi-static elasticity of the MCs is found to be very dependent on the shell thickness, the high frequency (5 MHz) elastic behavior of the core leads to a stable behavior of the MCs (from 2.5 to 3 GPa according to the shell thickness). Finally, the effect of thermal annealing on the MCs elasticity is investigated. The Young's modulus is found to decrease because of the reduction of the shell thickness due to the loss of the polymer. PMID:27058449

  20. Microbiological tap water profile of a medium-sized building and effect of water stagnation.

    PubMed

    Lipphaus, Patrick; Hammes, Frederik; Kötzsch, Stefan; Green, James; Gillespie, Simon; Nocker, Andreas

    2014-01-01

    Whereas microbiological quality of drinking water in water distribution systems is routinely monitored for reasons of legal compliance, microbial numbers in tap water are grossly understudied. Motivated by gross differences in water from private households, we applied in this study flow cytometry as a rapid analytical method to quantify microbial concentrations in water sampled at diverse taps in a medium size research building receiving chlorinated water. Taps differed considerably in frequency of usage and were located in laboratories, bathrooms, and a coffee kitchen. Substantial differences were observed between taps with concentrations (per mL) in the range from 6.29 x 10(3) to 7.74 x 10(5) for total cells and from 1.66 x 10(3) to 4.31 x 10(5) for intact cells. The percentage of intact cells varied between 7% and 96%. Water from taps with very infrequent use showed the highest bacterial numbers and the highest proportions of intact cells. Stagnation tended to increase microbial numbers in water from those taps which were otherwise frequently used. Microbial numbers in other taps that were rarely opened were not affected by stagnation as their water is probably mostly stagnant. For cold water taps, microbial numbers and the percentage of intact cells tended to decline with flushing with the greatest decline for taps used least frequently whereas microbial concentrations in water from hot water taps tended to be somewhat more stable. We conclude that microbiological water quality is mainly determined by building-specific parameters. Tap water profiling can provide valuable insight into plumbing system hygiene and maintenance. PMID:24645441

  1. Contamination of tap water on an ocean-going vessel.

    PubMed

    Meyer, Gabriele; Neubauer, Birger; Schepers, Bernd-Fred

    2007-04-01

    The crew of a container vessel detected an aromatic odor of the tap water that was produced on board. As the origin of the contamination was not obvious, water was taken at different sampling sites of the water supply of the vessel. Samples were analyzed for occurrence of chemical substances by GC-MS. Thereby xylene and ethylbenzene were detected in nearly each sample. The highest xylene concentration was found in the sample from the fresh water tank. As xylene was used as solvent in the tank coating, it could be concluded that it was released by the coating. Consequently, the crew was advised to ventilate and clean the fresh water tanks. PMID:17616872

  2. The BaF sub 2 photon spectrometer TAPS

    SciTech Connect

    Novotny, R. . II Physics Inst.)

    1991-04-01

    The detector system TAPS (Two/Three Atm Photon Spectrometer) has been designed and installed to study high energy photons as well neutral mesons produced in relativistic heavy ion reactions. The spectrometer will consist of up to 384 individual BaF{sub 2}-modules packed in arrays of 64 scintillators. Each spectrometer arm, which carries two detector blocks, can be moved around the target location independently. This paper presents the design concept, the specifications of the individual scintillator and test results of sub-arrays performed with monochromatic photons and charged particles. first experiments at GANIL and SIS have been performed exploiting heavy ion beams up to a projectile energy of 1GeV/u.

  3. Towards metering tap water by Lorentz force velocimetry

    NASA Astrophysics Data System (ADS)

    Vasilyan, Suren; Ebert, Reschad; Weidner, Markus; Rivero, Michel; Halbedel, Bernd; Resagk, Christian; Fröhlich, Thomas

    2015-11-01

    In this paper, we present enhanced flow rate measurement by applying the contactless Lorentz Force Velocimetry (LFV) technique. Particularly, we show that the LFV is a feasible technique for metering the flow rate of salt water in a rectangular channel. The measurements of the Lorentz forces as a function of the flow rate are presented for different electrical conductivities of the salt water. The smallest value of conductivity is achieved at 0.06 S·m-1, which corresponds to the typical value of tap water. In comparison with previous results, the performance of LFV is improved by approximately 2 orders of magnitude by means of a high-precision differential force measurement setup. Furthermore, the sensitivity curve and the calibration factor of the flowmeter are provided based on extensive measurements for the flow velocities ranging from 0.2 to 2.5 m·s-1 and conductivities ranging from 0.06 to 10 S·m-1.

  4. Channel erosion surveys along the TAPS route, Alaska, 1977

    USGS Publications Warehouse

    Loeffler, Robert M.; Childers, Joseph M.

    1977-01-01

    Channel surveys were made along the trans-Alaska pipeline system (TAPS) route during 1977 at the same 28 sites that were studied in 1976. In addition, a new site at pipeline mile 22 near Deadhorse (alignment No 134) along the Sagavanirktok River was put under surveillance. Except for changes wrought by the completion of construction, most of the sites showed very little change. Significant events include virtual completion of all construction activities along the pipeline, the pipeline startup , and the breakup flood along the Sagavanirktok River which breached many river-training structures. In general, 1977 saw heavy flooding on streams draining the north and south slopes of the Brooks Range and only moderate flooding on streams further south. Aerial photogrammetric surveys were used again in 1977 on the same seven sites as in 1976. Results document the applicability of the method for channel erosion studies. (Woodard-USGS)

  5. Channel erosion surveys along TAPS route, Alaska, 1974

    USGS Publications Warehouse

    Childers, Joseph; Jones, Stanley H.

    1975-01-01

    Repeated site surveys and aerial photographs at 26 stream crossings along the trans-Alaska pipeline system (TAPS) route during the period 1969-74 provide chronologie records of channel changes that predate pipeline-related construction at the sites. The 1974 surveys and photographs show some of the channel changes wrought by construction of the haul road from the Yukon River to Prudhoe Bay and by construction of camps and working pads all along the pipeline route. No pipeline crossings were constructed before 1975. These records of channel changes together with flood and icing measurements are part of the United States Department of the lnterior's continuing surveillance program to document the hydrologic aspects of the trans-Alaska pipeline and its environmental impacts.

  6. Cyclospora cayetanensis travels in tap water on Italian trains.

    PubMed

    Giangaspero, A; Marangi, M; Arace, E

    2015-03-01

    Tap water samples from the toilets of an Italian national railway train were collected over a period of 10 months and tested for the presence of Cyclospora cayetanensis (C. cayetanensis) using EvaGreen® real-time polymerase chain reaction (RT-PCR) assay coupled with high resolution melting (HRM) analysis for protozoan detection and oocyst quantification. C. cayetanensis positive samples were detected in March, April, and May 2013, with the number of oocysts of 4, 5, and 11 per liter, respectively. This is the first finding of C. cayetanensis in water samples in Italy. The findings call for an improvement of hygiene and water safety by the Italian national railway company. PMID:25719480

  7. Quantitative risk assessment of Cryptosporidium in tap water in Ireland.

    PubMed

    Cummins, E; Kennedy, R; Cormican, M

    2010-01-15

    Cryptosporidium species are protozoan parasites associated with gastro-intestinal illness. Following a number of high profile outbreaks worldwide, it has emerged as a parasite of major public health concern. A quantitative Monte Carlo simulation model was developed to evaluate the annual risk of infection from Cryptosporidium in tap water in Ireland. The assessment considers the potential initial contamination levels in raw water, oocyst removal and decontamination events following various process stages, including coagulation/flocculation, sedimentation, filtration and disinfection. A number of scenarios were analysed to represent potential risks from public water supplies, group water schemes and private wells. Where surface water is used additional physical and chemical water treatment is important in terms of reducing the risk to consumers. The simulated annual risk of illness for immunocompetent individuals was below 1 x 10(-4) per year (as set by the US EPA) except under extreme contamination events. The risk for immunocompromised individuals was 2-3 orders of magnitude greater for the scenarios analysed. The model indicates a reduced risk of infection from tap water that has undergone microfiltration, as this treatment is more robust in the event of high contamination loads. The sensitivity analysis highlighted the importance of watershed protection and the importance of adequate coagulation/flocculation in conventional treatment. The frequency of failure of the treatment process is the most important parameter influencing human risk in conventional treatment. The model developed in this study may be useful for local authorities, government agencies and other stakeholders to evaluate the likely risk of infection given some basic input data on source water and treatment processes used. PMID:19945145

  8. How Well Do Computer-Generated Faces Tap Face Expertise?

    PubMed Central

    Crookes, Kate; Ewing, Louise; Gildenhuys, Ju-dith; Kloth, Nadine; Hayward, William G.; Oxner, Matt; Pond, Stephen; Rhodes, Gillian

    2015-01-01

    The use of computer-generated (CG) stimuli in face processing research is proliferating due to the ease with which faces can be generated, standardised and manipulated. However there has been surprisingly little research into whether CG faces are processed in the same way as photographs of real faces. The present study assessed how well CG faces tap face identity expertise by investigating whether two indicators of face expertise are reduced for CG faces when compared to face photographs. These indicators were accuracy for identification of own-race faces and the other-race effect (ORE)–the well-established finding that own-race faces are recognised more accurately than other-race faces. In Experiment 1 Caucasian and Asian participants completed a recognition memory task for own- and other-race real and CG faces. Overall accuracy for own-race faces was dramatically reduced for CG compared to real faces and the ORE was significantly and substantially attenuated for CG faces. Experiment 2 investigated perceptual discrimination for own- and other-race real and CG faces with Caucasian and Asian participants. Here again, accuracy for own-race faces was significantly reduced for CG compared to real faces. However the ORE was not affected by format. Together these results signal that CG faces of the type tested here do not fully tap face expertise. Technological advancement may, in the future, produce CG faces that are equivalent to real photographs. Until then caution is advised when interpreting results obtained using CG faces. PMID:26535910

  9. Sensitive detection of atrazine in tap water using TELISA.

    PubMed

    Qie, Zhiwei; Bai, Jialei; Xie, Bin; Yuan, Lin; Song, Nan; Peng, Yuan; Fan, Xianjun; Zhou, Huanying; Chen, Fengchun; Li, Shuang; Ning, Baoan; Gao, Zhixian

    2015-08-01

    A highly sensitive flow injection analysis (FIA)-based thermal enzyme-linked immunoassay, TELISA, was developed for the rapid detection of atrazine (ATZ) in tap water. ATZ and β-lactamase-labeled ATZ were employed in a competitive immunoassay using a monoclonal antibody (mAb). After the off-column liquid-phase competition, the mAb was captured on the Protein G Sepharose™ 4 Fast Flow (PGSFF) column support material. Injected β-lactamase substrate ampicillin was degraded by the column-bound ATZ-β-lactamase, generating a detectable heat signal. Several assay parameters were optimized, including substrate concentration, flow rates and regeneration conditions, as well as the mAb and ATZ-β dilution ratios and concentrations. The assay linear range was 0.73-4.83 ng mL(-1) with a detection limit of 0.66 ng mL(-1). An entire heat signal requires 10 min for generation, and the cycle time is less than 40 min. The results were reproducible and stable. ATZ-spiked tap water samples exhibited a recovery rate of 103%-116%, which correlated with the UHPLC-MS/MS measurements. We attributed this significant increase in sensitivity over our previously published work to the following factors: (i) the capture of already-formed immune complexes on the column via immobilized Protein G, which eliminated chemical immobilization of the antibody; (ii) off-column preincubation allows the formation of immune complexes under nearly ideal conditions; and (iii) multiple buffers can be used to, in one case, enhance immune-complex formation and in the other to maximize enzymatic activity. Furthermore, the scheme creates a universal assay platform in which sensing is performed in the off-column incubation and detection after capture in the enzyme thermistor (ET) detector, which opens up the possibility of detecting any antigen for which antibodies were available. PMID:26061585

  10. Expanding the Universe of "Astronomy on Tap" Public Outreach Events

    NASA Astrophysics Data System (ADS)

    Rice, Emily L.; Levine, Brian; Livermore, Rachael C.; Silverman, Jeffrey M.; LaMassa, Stephanie M.; Tyndall, Amy; Muna, Demitri; Garofali, Kristen; Morris, Brett; Byler, Nell; Fyhrie, Adalyn; Rehnberg, Morgan; Hart, Quyen N.; Connelly, Jennifer L.; Silvia, Devin W.; Morrison, Sarah J.; Agarwal, Bhaskar; Tremblay, Grant; Schwamb, Megan E.

    2016-01-01

    Astronomy on Tap (AoT, astronomyontap.org) is free public outreach event featuring engaging science presentations in bars, often combined with music, games, and prizes, to encourage a fun, interactive atmosphere. AoT events feature several short astronomy-related presentations primarily by local professional scientists, but also by visiting scientists, students, educators, amatuer astronomers, writers, and artists. Events are held in social venues (bars, coffee shops, art galleries, etc.) in order to bring science directly to the public in a relaxed, informal atmosphere. With this we hope to engage a more diverse audience than typical lectures at academic and cultural institutions and to develop enthusiasm for science among voting, tax-paying adults. The flexible format and content of an AoT event is easy to adapt and expand based on the priorities, resources, and interests of local organizers. The social nature of AoT events provides important professional development and networking opportunities in science communication. Since the first New York City event in April 2013, Astronomy on Tap has expanded to more than ten cities globally, including monthly events in NYC, Austin, Seattle, and Tucson; semi-regular events in Columbus, New Haven, Santiago, Toronto, and Denver; occasional (so far) events in Rochester (NY), Baltimore, Lansing, and Washington, DC; and one-off events in Chicago and Taipei. Several venues regularly attract audiences of over 200 people. We have received media coverage online, in print, and occasionally even on radio and television. In this poster we describe the overarching goals and characteristics of AoT events, distinct adaptations of various locations, resources we have developed, and the methods we use to coordinate among the worldwide local organizers.

  11. TAP Helps States and Local Governments Reach Their Wind Power Goals

    SciTech Connect

    Not Available

    2007-08-01

    Technical Assistance Project: Wind and Hydropower Program provides information to state and local officials regarding the U.S. Department of Energy's Technical Assistance Project (TAP). The TAP program provides access to wind energy experts at U.S. Department of Energy (DOE) national laboratories, including the National Renewable Energy Laboratory (NREL), Oak Ridge National Laboratory (ORNL), and Lawrence Berkeley National Laboratory (LBNL).

  12. TAp63 prevents premature aging by promoting adult stem cell maintenance

    PubMed Central

    Su, Xiaohua; Paris, Maryline; Gi, Young Jin; Tsai, Kenneth Y.; Cho, Min Soon; Lin, Yu-Li; Biernaskie, Jeffrey A.; Sinha, Satrajit; Prives, Carol; Pevny, Larysa H.; Miller, Freda D.; Flores, Elsa R.

    2012-01-01

    SUMMARY The cellular mechanisms that regulate the maintenance of adult tissue stem cells are still largely unknown. We show here that the p53 family member, TAp63, is essential for maintenance of epidermal and dermal precursors and that, in its absence, these precursors senesce and skin ages prematurely. Specifically, we have developed a TAp63 conditional knockout mouse and used it to ablate TAp63 in the germline (TAp63−/−) or in K14-expressing cells in the basal layer of the epidermis (TAp63fl/fl;K14cre+). TAp63−/− mice age prematurely and develop blisters, skin ulcerations, senescence of hair follicle-associated dermal and epidermal cells, and decreased hair morphogenesis. These phenotypes are likely due to loss of TAp63 in dermal and epidermal precursors since both cell types show defective proliferation, early senescence, and genomic instability. These data indicate that TAp63 serves to maintain adult skin stem cells by regulating cellular senescence and genomic stability, thereby preventing premature tissue aging. PMID:19570515

  13. An Evaluation of the Teacher Advancement Program (TAP) in Chicago: Year Two Impact Report

    ERIC Educational Resources Information Center

    Glazerman, Steven; Seifullah, Allison

    2010-01-01

    In 2007, the Chicago Public Schools (CPS) began implementing a schoolwide reform called the Teacher Advancement Program (TAP) using funds from the federal Teacher Incentive Fund (TIF) and private foundations. Under the TAP model, teachers can earn extra pay and responsibilities through promotion to mentor or master teacher as well as annual…

  14. Tapping into the Academic Workforce: Beyond Complaints to Dialogue, Resolution and Accommodation.

    ERIC Educational Resources Information Center

    Labeouf, Joanne P.

    This document highlights some of the main problems in using temporary, adjunct, and part-time (TAP) faculty, a practice that is becoming commonplace in higher education, especially at the community college level. Institutions use TAP faculty for several reasons: economic motivation, staffing flexibility in times of fluctuating enrollments,…

  15. TAp63 regulates oncogenic miR-155 to mediate migration and tumour growth

    PubMed Central

    Mattiske, Sam; Ho, Kristen; Noll, Jacqueline E.; Neilsen, Paul M.; Callen, David F.; Suetani, Rachel J.

    2013-01-01

    miR-155 is an oncogenic microRNA which is upregulated in many solid cancers. The targets of miR-155 are well established, with over 100 confirmed mRNA targets. However, the regulation of miR-155 and the basis of its upregulation in cancer is not well understood. We have previously shown that miR-155 is regulated by p63, and here we investigate the role of the major p63 isoforms TAp63 and ΔNp63 in this regulation. When the TAp63 isoform was knocked down, or exogenously overexpressed, miR-155 levels were elevated in response to TAp63 knockdown or reduced in response to TAp63 overexpression. The ΔNp63 isoform is shown to directly bind to the p63 response element on the miR-155 host gene, and this binding is enriched when TAp63 is knocked down. This could indicate that TAp63 prevents ΔNp63 from binding to the miR-155 host gene. The knockdown of TAp63, and the subsequent elevation of miR-155, enhances migration and tumour growth similar to that seen when directly overexpressing miR-155. The migratory phenotype is abrogated when miR-155 is inhibited, indicating that miR-155 is responsible for the phenotypic effect of TAp63 knockdown. PMID:24177167

  16. An Evaluation of the Chicago Teacher Advancement Program (Chicago TAP) after Four Years. Final Report

    ERIC Educational Resources Information Center

    Glazerman, Steven; Seifullah, Allison

    2012-01-01

    In 2007, using funds from the federal Teacher Incentive Fund (TIF) and private foundations, the Chicago Public Schools (CPS) began piloting its version of a schoolwide reform model called the Teacher Advancement Program (TAP). Under the TAP model, teachers can earn extra pay and take on increased responsibilities through promotion (to mentor…

  17. XPS and AFM Study of GaAs Surface Treatment

    SciTech Connect

    Contreras-Guerrero, R.; Wallace, R. M.; Aguirre-Francisco, S.; Herrera-Gomez, A.; Lopez-Lopez, M.

    2008-11-13

    Obtaining smooth and atomically clean surfaces is an important step in the preparation of a surface for device manufacturing. In this work different processes are evaluated for cleaning a GaAs surface. A good surface cleaning treatment is that which provides a high level of uniformity and controllability of the surface. Different techniques are useful as cleaning treatments depending on the growth process to be used. The goal is to remove the oxygen and carbon contaminants and then form a thin oxide film to protect the surface, which is easy to remove later with thermal desorption mechanism like molecular beam epitaxy (MBE) with minimal impact to the surface. In this study, atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were used to characterize the structure of the surface, the composition, as well as detect oxygen and carbon contaminant on the GaAs surface. This study consists in two parts. The first part the surface was subjected to different chemical treatments. The chemical solutions were: (a)H{sub 2}SO{sub 4}:H{sub 2}O{sub 2}:H{sub 2}O(4:1:100), (b) HCl: H{sub 2}O(1:3), (c)NH{sub 4}OH 29%. The treatments (a) and (b) reduced the oxygen on the surface. Treatment (c) reduces carbon contamination. In the second part we made MOS devices on the surfaces treated. They were characterized by CV and IV electrical measurements. They show frequency dispersion.

  18. AFM nanoscale indentation in air of polymeric and hybrid materials with highly different stiffness

    NASA Astrophysics Data System (ADS)

    Suriano, Raffaella; Credi, Caterina; Levi, Marinella; Turri, Stefano

    2014-08-01

    In this study, nanomechanical properties of a variety of polymeric materials was investigated by means of AFM. In particular, selecting different AFM probes, poly(methyl methacrylate) (PMMA), polydimethylsiloxane (PDMS) bulk samples, sol-gel hybrid thin films and hydrated hyaluronic acid hydrogels were indented in air to determine the elastic modulus. The force-distance curves and the indentation data were found to be greatly affected by the cantilever stiffness and by tip geometry. AFM indentation tests show that the choice of the cantilever spring constant and of tip shape is crucially influenced by elastic properties of samples. When adhesion-dominated interactions occur between the tip and the surface of samples, force-displacement curves reveal that a suitable functionalization of AFM probes allows the control of such interactions and the extraction of Young' modulus from AFM curves that would be otherwise unfeasible. By applying different mathematical models depending on AFM probes and materials under investigation, the values of Young's modulus were obtained and compared to those measured by rheological and dynamic mechanical analysis or to literature data. Our results show that a wide range of elastic moduli (10 kPa-10 GPa) can be determined by AFM in good agreement with those measured by conventional macroscopic measurements.

  19. Tuning the resonance of a photonic crystal microcavity with an AFM probe.

    PubMed

    Märki, Iwan; Salt, Martin; Herzig, Hans Peter

    2006-04-01

    We present theoretical and experimental results on switching and tuning of a two-dimensional photonic crystal resonant microcavity by means of a silicon AFM tip, probing the highly localized optical field in the vicinity of the cavity. On-off switching and modulation of the transmission signal in the kHz range is achieved by bringing an AFM tip onto the center of the microcavity, inducing a damping effect on the transmission resonance. Tuning of the resonant wavelength in the order of several nanometers becomes possible by inserting the AFM tip into one of the holes of the Bragg mirror forming the microcavity in the propagation direction. PMID:19516436

  20. Development of portable experimental set-up for AFM to work at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Agarwal, D. H.; Bhatt, P. M.; Pathan, A. M.; Patel, Hitarthi; Joshi, U. S.

    2012-06-01

    We report on the designing aspects and fabrication of low temperature atomic force microscope (AFM) to study the surface structures of nanomaterials. Several key features of design including liquid nitrogen reservoir, vacuum chamber, vibration isolation table etc. have been presented. The whole set up was assembled in-house at a fairly low cost to be used with any commercial AFM system. The surface morphology of important oxide (In0.94Sn0.04)2O3 (ITO) thin film nanostructures has been investigated using the cryogenic AFM set up.

  1. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW).

    PubMed

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin; Anderson, Bruce; Cheng, Shuiping

    2016-05-15

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg · L(-1)). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (ΦPS II) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. PMID:26897579

  2. MetaRep, an extended CMAS 3D program to visualize mafic (CMAS, ACF-S, ACF-N) and pelitic (AFM-K, AFM-S, AKF-S) projections

    NASA Astrophysics Data System (ADS)

    France, Lydéric; Nicollet, Christian

    2010-06-01

    MetaRep is a program based on our earlier program CMAS 3D. It is developed in MATLAB ® script. MetaRep objectives are to visualize and project major element compositions of mafic and pelitic rocks and their minerals in the pseudo-quaternary projections of the ACF-S, ACF-N, CMAS, AFM-K, AFM-S and AKF-S systems. These six systems are commonly used to describe metamorphic mineral assemblages and magmatic evolutions. Each system, made of four apices, can be represented in a tetrahedron that can be visualized in three dimensions with MetaRep; the four tetrahedron apices represent oxides or combination of oxides that define the composition of the projected rock or mineral. The three-dimensional representation allows one to obtain a better understanding of the topology of the relationships between the rocks and minerals and relations. From these systems, MetaRep can also project data in ternary plots (for example, the ACF, AFM and AKF ternary projections can be generated). A functional interface makes it easy to use and does not require any knowledge of MATLAB ® programming. To facilitate the use, MetaRep loads, from the main interface, data compiled in a Microsoft Excel ™ spreadsheet. Although useful for scientific research, the program is also a powerful tool for teaching. We propose an application example that, by using two combined systems (ACF-S and ACF-N), provides strong confirmation in the petrological interpretation.

  3. Tip Based Nanofabrication Using Multi-mode Scanning Probe Microscopy

    NASA Astrophysics Data System (ADS)

    Hu, Weihua

    Scanning probe microscopy (SPM) based nanotechnology is a promising technology in nano-device fabrication. It is able to both manipulate nanostructures and characterize the created nanopatterns using the nano-tip of the scanning probe on a mechanical basis or electrical basis. With the tip and device on similar scales, nano-tip based fabrication permits accurate control over the device geometry through tip manipulation with nanometer (or better) accuracy. However, SPM based nanofabrication is a slow process because the scanning velocity of the microscopy is low. Large, multi-tip arrays offer the possibility for parallel device fabrication, allowing mass fabrication with nanometer control. The goal of Tip-directed Field-emission Assisted Nanofabrication (TFAN) project was to realize parallel fabrication using our probe arrays. We started by fabricating nanodevice using one single probe. In this work, we investigated the study of fabricating single electron transistor (SET) using one single SPM probe. There were four stages we went through toward fabricating a SET. The first stage was to accomplish atomic-precision lithography in TFAN system. Atomic level lithography was achieved by desorbing hydrogen atoms, which were previously adsorbed to the Si(100)-2 × 1 surface, in ultrahigh vacuum scanning tunneling microscopy (UHV-STM). The second stage was to develop method for fabricating SET. SPM based local oxidation was chosen as the method to fabricate a SET on a thin titanium (Ti) film. A multi-mode SPM oxidation method was developed, in which both scanning tunneling microscopy (STM) mode and atomic microscopy (AFM) mode local oxidation were used to fabricated Ti-TiOx-Ti structures with the same conductive AFM probe. This multi-mode method enabled significantly fine feature size control by STM mode, working on insulating SiO2 substrates needed to isolate the device by AFM mode and in situ electrical characterization with conductive AFM mode. After developing the multi-mode

  4. Characterization and allelic variation of the transporters associated with antigen processing (TAP) genes in the domestic dog (Canis lupus familiaris).

    PubMed

    Gojanovich, Gregory S; Ross, Peter; Holmer, Savannah G; Holmes, Jennifer C; Hess, Paul R

    2013-12-01

    The function of the transporters associated with antigen processing (TAP) complex is to shuttle antigenic peptides from the cytosol to the endoplasmic reticulum to load MHC class I molecules for CD8(+) T-cell immunosurveillance. Here we report the promoter and coding regions of the canine TAP1 and TAP2 genes, which encode the homologous subunits forming the TAP heterodimer. By sampling genetically divergent breeds, polymorphisms in both genes were identified, although there were few amino acid differences between alleles. Splice variants were also found. When aligned to TAP genes of other species, functional regions appeared conserved, and upon phylogenetic analysis, canine sequences segregated appropriately with their orthologs. Transfer of the canine TAP2 gene into a murine TAP2-defective cell line rescued surface MHC class I expression, confirming exporter function. This data should prove useful in investigating the association of specific TAP defects or alleles with immunity to intracellular pathogens and cancer in dogs. PMID:23892057

  5. Characterization and allelic variation of the transporters associated with antigen processing (TAP) genes in the domestic dog (Canis lupus familiaris)

    PubMed Central

    Gojanovich, Gregory S.; Ross, Peter; Holmer, Savannah R.; Holmes, Jennifer C.; Hess, Paul R.

    2013-01-01

    The function of the transporters associated with antigen processing (TAP) complex is to shuttle antigenic peptides from the cytosol to the endoplasmic reticulum to load MHC class I molecules for CD8+ T-cell immunosurveillance. Here we report the promoter and coding regions of the canine TAP1 and TAP2 genes, which encode the homologous subunits forming the TAP heterodimer. By sampling genetically divergent breeds, polymorphisms in both genes were identified, although there were few amino acid differences between alleles. Splice variants were also found. When aligned to TAP genes of other species, functional regions appeared conserved, and upon phylogenetic analysis, canine sequences segregated appropriately with their orthologs. Transfer of the canine TAP2 gene into a murine TAP2-defective cell line rescued surface MHC class I expression, confirming exporter function. This data should prove useful in investigating the association of specific TAP defects or alleles with immunity to intracellular pathogens and cancer in dogs. PMID:23892057

  6. Probing Cytoskeletal Structures by Coupling Optical Superresolution and AFM Techniques for a Correlative Approach

    PubMed Central

    Chacko, Jenu Varghese; Zanacchi, Francesca Cella; Diaspro, Alberto

    2013-01-01

    In this article, we describe and show the application of some of the most advanced fluorescence superresolution techniques, STED AFM and STORM AFM microscopy towards imaging of cytoskeletal structures, such as microtubule filaments. Mechanical and structural properties can play a relevant role in the investigation of cytoskeletal structures of interest, such as microtubules, that provide support to the cell structure. In fact, the mechanical properties, such as the local stiffness and the elasticity, can be investigated by AFM force spectroscopy with tens of nanometers resolution. Force curves can be analyzed in order to obtain the local elasticity (and the Young's modulus calculation by fitting the force curves from every pixel of interest), and the combination with STED/STORM microscopy integrates the measurement with high specificity and yields superresolution structural information. This hybrid modality of superresolution-AFM working is a clear example of correlative multimodal microscopy. PMID:24027190

  7. Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM-SECM.

    PubMed

    Avdic, A; Lugstein, A; Wu, M; Gollas, B; Pobelov, I; Wandlowski, T; Leonhardt, K; Denuault, G; Bertagnolli, E

    2011-04-01

    We demonstrate a reliable microfabrication process for a combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) measurement tool. Integrated cone-shaped sensors with boron doped diamond (BDD) or gold (Au) electrodes were fabricated from commercially available AFM probes. The sensor formation process is based on mature semiconductor processing techniques, including focused ion beam (FIB) machining, and highly selective reactive ion etching (RIE). The fabrication approach preserves the geometry of the original AFM tips resulting in well reproducible nanoscaled sensors. The feasibility and functionality of the fully featured tips are demonstrated by cyclic voltammetry, showing good agreement between the measured and calculated currents of the cone-shaped AFM-SECM electrodes. PMID:21368355

  8. Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM-SECM

    NASA Astrophysics Data System (ADS)

    Avdic, A.; Lugstein, A.; Wu, M.; Gollas, B.; Pobelov, I.; Wandlowski, T.; Leonhardt, K.; Denuault, G.; Bertagnolli, E.

    2011-04-01

    We demonstrate a reliable microfabrication process for a combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) measurement tool. Integrated cone-shaped sensors with boron doped diamond (BDD) or gold (Au) electrodes were fabricated from commercially available AFM probes. The sensor formation process is based on mature semiconductor processing techniques, including focused ion beam (FIB) machining, and highly selective reactive ion etching (RIE). The fabrication approach preserves the geometry of the original AFM tips resulting in well reproducible nanoscaled sensors. The feasibility and functionality of the fully featured tips are demonstrated by cyclic voltammetry, showing good agreement between the measured and calculated currents of the cone-shaped AFM-SECM electrodes.

  9. Using XAFS, EDAX and AFM in comparative study of various natural and synthetic emeralds

    NASA Astrophysics Data System (ADS)

    Parikh, P.; Saini, N. L.; Dalela, S.; Bhardwaj, D. M.; Fernandes, S.; Gupta, R. P.; Garg, K. B.

    2003-01-01

    We have performed XAFS, EDAX and AFM studies on some natural and synthetic emeralds. While the XAFS results yield information on changes in the valence of the Cr ion and the n-n distance the AFM is used to determine the areal atomic density on surface of the crystals. It is a pilot study to explore if the three techniques can offer a possible way of distinguishing between the natural and synthetic emeralds and the results are promising.

  10. A Multifunctional Frontloading Approach for Repeated Recycling of a Pressure-Controlled AFM Micropipette.

    PubMed

    Roder, Phillip; Hille, Carsten

    2015-01-01

    Fluid force microscopy combines the positional accuracy and force sensitivity of an atomic force microscope (AFM) with nanofluidics via a microchanneled cantilever. However, adequate loading and cleaning procedures for such AFM micropipettes are required for various application situations. Here, a new frontloading procedure is described for an AFM micropipette functioning as a force- and pressure-controlled microscale liquid dispenser. This frontloading procedure seems especially attractive when using target substances featuring high costs or low available amounts. Here, the AFM micropipette could be filled from the tip side with liquid from a previously applied droplet with a volume of only a few μL using a short low-pressure pulse. The liquid-loaded AFM micropipettes could be then applied for experiments in air or liquid environments. AFM micropipette frontloading was evaluated with the well-known organic fluorescent dye rhodamine 6G and the AlexaFluor647-labeled antibody goat anti-rat IgG as an example of a larger biological compound. After micropipette usage, specific cleaning procedures were tested. Furthermore, a storage method is described, at which the AFM micropipettes could be stored for a few hours up to several days without drying out or clogging of the microchannel. In summary, the rapid, versatile and cost-efficient frontloading and cleaning procedure for the repeated usage of a single AFM micropipette is beneficial for various application situations from specific surface modifications through to local manipulation of living cells, and provides a simplified and faster handling for already known experiments with fluid force microscopy. PMID:26636981

  11. A Multifunctional Frontloading Approach for Repeated Recycling of a Pressure-Controlled AFM Micropipette

    PubMed Central

    Roder, Phillip; Hille, Carsten

    2015-01-01

    Fluid force microscopy combines the positional accuracy and force sensitivity of an atomic force microscope (AFM) with nanofluidics via a microchanneled cantilever. However, adequate loading and cleaning procedures for such AFM micropipettes are required for various application situations. Here, a new frontloading procedure is described for an AFM micropipette functioning as a force- and pressure-controlled microscale liquid dispenser. This frontloading procedure seems especially attractive when using target substances featuring high costs or low available amounts. Here, the AFM micropipette could be filled from the tip side with liquid from a previously applied droplet with a volume of only a few μL using a short low-pressure pulse. The liquid-loaded AFM micropipettes could be then applied for experiments in air or liquid environments. AFM micropipette frontloading was evaluated with the well-known organic fluorescent dye rhodamine 6G and the AlexaFluor647-labeled antibody goat anti-rat IgG as an example of a larger biological compound. After micropipette usage, specific cleaning procedures were tested. Furthermore, a storage method is described, at which the AFM micropipettes could be stored for a few hours up to several days without drying out or clogging of the microchannel. In summary, the rapid, versatile and cost-efficient frontloading and cleaning procedure for the repeated usage of a single AFM micropipette is beneficial for various application situations from specific surface modifications through to local manipulation of living cells, and provides a simplified and faster handling for already known experiments with fluid force microscopy. PMID:26636981

  12. Automatic and Objective Assessment of Alternating Tapping Performance in Parkinson's Disease

    PubMed Central

    Memedi, Mevludin; Khan, Taha; Grenholm, Peter; Nyholm, Dag; Westin, Jerker

    2013-01-01

    This paper presents the development and evaluation of a method for enabling quantitative and automatic scoring of alternating tapping performance of patients with Parkinson's disease (PD). Ten healthy elderly subjects and 95 patients in different clinical stages of PD have utilized a touch-pad handheld computer to perform alternate tapping tests in their home environments. First, a neurologist used a web-based system to visually assess impairments in four tapping dimensions (‘speed’, ‘accuracy’, ‘fatigue’ and ‘arrhythmia’) and a global tapping severity (GTS). Second, tapping signals were processed with time series analysis and statistical methods to derive 24 quantitative parameters. Third, principal component analysis was used to reduce the dimensions of these parameters and to obtain scores for the four dimensions. Finally, a logistic regression classifier was trained using a 10-fold stratified cross-validation to map the reduced parameters to the corresponding visually assessed GTS scores. Results showed that the computed scores correlated well to visually assessed scores and were significantly different across Unified Parkinson's Disease Rating Scale scores of upper limb motor performance. In addition, they had good internal consistency, had good ability to discriminate between healthy elderly and patients in different disease stages, had good sensitivity to treatment interventions and could reflect the natural disease progression over time. In conclusion, the automatic method can be useful to objectively assess the tapping performance of PD patients and can be included in telemedicine tools for remote monitoring of tapping. PMID:24351667

  13. X-ray microtomography study of the compaction process of rods under tapping

    NASA Astrophysics Data System (ADS)

    Fu, Yang; Xi, Yan; Cao, Yixin; Wang, Yujie

    2012-05-01

    We present an x-ray microtomography study of the compaction process of cylindrical rods under tapping. The process is monitored by measuring the evolution of the orientational order parameter, local, and overall packing densities as a function of the tapping number for different tapping intensities. The slow relaxation dynamics of the orientational order parameter can be well fitted with a stretched-exponential law with stretching exponents ranging from 0.9 to 1.6. The corresponding relaxation time versus tapping intensity follows an Arrhenius behavior which is reminiscent of the slow dynamics in thermal glassy systems. We also investigated the boundary effect on the ordering process and found that boundary rods order faster than interior ones. In searching for the underlying mechanism of the slow dynamics, we estimated the initial random velocities of the rods under tapping and found that the ordering process is compatible with a diffusion mechanism. The average coordination number as a function of the tapping number at different tapping intensities has also been measured, which spans a range from 6 to 8.

  14. Cowpox virus protein CPXV012 eludes CTLs by blocking ATP binding to TAP.

    PubMed

    Luteijn, Rutger D; Hoelen, Hanneke; Kruse, Elisabeth; van Leeuwen, Wouter F; Grootens, Jennine; Horst, Daniëlle; Koorengevel, Martijn; Drijfhout, Jan W; Kremmer, Elisabeth; Früh, Klaus; Neefjes, Jacques J; Killian, Antoinette; Lebbink, Robert Jan; Ressing, Maaike E; Wiertz, Emmanuel J H J

    2014-08-15

    CD8(+) CTLs detect virus-infected cells through recognition of virus-derived peptides presented at the cell surface by MHC class I molecules. The cowpox virus protein CPXV012 deprives the endoplasmic reticulum (ER) lumen of peptides for loading onto newly synthesized MHC class I molecules by inhibiting the transporter associated with Ag processing (TAP). This evasion strategy allows the virus to avoid detection by the immune system. In this article, we show that CPXV012, a 9-kDa type II transmembrane protein, prevents peptide transport by inhibiting ATP binding to TAP. We identified a segment within the ER-luminal domain of CPXV012 that imposes the block in peptide transport by TAP. Biophysical studies show that this domain has a strong affinity for phospholipids that are also abundant in the ER membrane. We discuss these findings in an evolutionary context and show that a frameshift deletion in the CPXV012 gene in an ancestral cowpox virus created the current form of CPXV012 that is capable of inhibiting TAP. In conclusion, our findings indicate that the ER-luminal domain of CPXV012 inserts into the ER membrane, where it interacts with TAP. CPXV012 presumably induces a conformational arrest that precludes ATP binding to TAP and, thus, activity of TAP, thereby preventing the presentation of viral peptides to CTLs. PMID:25024387

  15. TAp63 is a master transcriptional regulator of lipid and glucose metabolism

    PubMed Central

    Su, Xiaohua; Gi, Young Jin; Chakravarti, Deepavali; Chan, Io Long; Zhang, Aijun; Xia, Xuefeng; Tsai, Kenneth Y.; Flores, Elsa R.

    2012-01-01

    SUMMARY TAp63 prevents premature aging suggesting a link to genes that regulate longevity. Further characterization of TAp63−/− mice revealed that these mice develop obesity, insulin resistance, and glucose intolerance, similar to those seen in mice lacking two key metabolic regulators, Silent information regulator T1 (Sirt1) and AMPK. While the roles of Sirt1 and AMPK in metabolism have been well studied, their upstream regulators are not well understood. We found that TAp63 is important in regulating energy metabolism by accumulating in response to metabolic stress and transcriptionally activating Sirt1, AMPKα2, and LKB1 resulting in increased fatty acid synthesis and decreased fatty acid oxidation. Moreover, we found that TAp63 lowers blood glucose levels in response to metformin. Restoration of Sirt1, AMPKα2, and LKB1 in TAp63−/− mice rescued some of the metabolic defects of the TAp63−/− mice. Our study defines a role for TAp63 in metabolism and weight control. PMID:23040072

  16. Cold tapping method shows promise for subsea repair

    SciTech Connect

    Not Available

    1983-07-01

    The Comex/Konsberg Total Marine Norsk project consists of positioning two Kleber plugs into the pipe to isolate the damaged section. In subsea pipe line repair, two main types of damage can be considered: 1. wet buckle; 2. dry buckle. A serious wet buckle means a hole in the line and the line operator will shut down production and flood the line with a corrosion inhibitor in order to minimize pollution and loss of gas. The line is flooded and the repair procedure is conducted without use of ''tapping'' techniques. A standard hyperbaric welding operation can be done by use of wellknown and proven diving methods. A dry buckle or a small leakage means the line is able to keep pressure and move gas. However, a buckle often means an obstruction to pigs. By experience the operator knows that a dry buckle strongly weakens the line and may grow gradually into a wet buckle. Because the operator first wants to keep line output reliability, he prefers to replace the damaged section as soon as the buckle is located.

  17. Channel erosion surveys along TAPS route, Alaska, 1976

    USGS Publications Warehouse

    Doyle, Paul F.; Childers, Joseph M.

    1977-01-01

    Channel surveys were made along the TAPS (Trans-Alaska Pipeline System) route during 1976 at the same 27 sites that were surveyed in 1975. One additional site was put under surveillance in 1976. Except for construction changes wrought by installation of the pipeline, most of the sites surveyed showed very little change since the 1975 surveys. Some of the significant events of 1976 at the monitored crossing sites include: glacier-dammed lake break-out floods on the Tazlina and Tsina Rivers, severe icings on the Gulkana River which resulted in a spring flood 3-4 feet (1 meter) over banktop, and virtual completion of all the buried crossings and all but one overhead crossing before the 1976 channel erosion resurveys were made. Aerial photogrammetric surveys were used again in 1976 on the same seven sites as in 1975. Comparison of the photogrammetric surveys with each other and with on-the-ground surveys indicate that the method is generally applicable for channel erosion studies. However, it requires engineering judgement and personal knowledge of the site to avoid reaching inaccurate conclusions about channel change in some instances. (Woodard-USGS)

  18. Sphingomonas hankyongensis sp. nov. isolated from tap water.

    PubMed

    Yun, Sung-Sik; Siddiqi, Muhammad Zubair; Lee, Soon-Youl; Kim, Minseok S; Choi, KangDuk; Im, Wan-Taek

    2016-10-01

    A Gram reaction-negative, strictly aerobic, non-motile, translucent and rod-shaped bacterium (designated W1-2-4(T)) isolated from tap water was characterized by a polyphasic approach to clarify its taxonomic position. Strain W1-2-4(T) was observed to grow optimally at 25-30 °C and at pH 6.5 on nutrient agar. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain W1-2-4(T) belongs to the genus Sphingomonas and is most closely related to the Sphingomonas fennica K101(T) (95.3 % similarity). The G+C content of genomic DNA was 67.1 mol%. Chemotaxonomic data [major ubiquinone-Q-10, major polyamine-homospermidine, major fatty acids-summed feature 8 (comprising C18:1 ω7c/ω6c), C16:0 and C14:0 2OH] supported the affiliation of strain W1-2-4(T) to the genus Sphingomonas. Strain W1-2-4(T) could be differentiated genotypically and phenotypically from the recognized species of the genus Sphingomonas. The novel isolate therefore represents a novel species, for which the name Sphingomonas hankyongensis sp. nov. is proposed, with the type strain W1-2-4(T) (=KACC 18308(T) = LMG 28595(T)). PMID:27177900

  19. AFM/CLSM data visualization and comparison using an open-source toolkit.

    PubMed

    Rajwa, Bartek; McNally, Helen A; Varadharajan, Padma; Sturgis, Jennifer; Robinson, J Paul

    2004-06-01

    There is a vast difference in the traditional presentation of AFM data and confocal data. AFM data are presented as surface contours while confocal data are usually visualized using either surface- or volume-rendering techniques. Finding a common meaningful visualization platform is not an easy task. AFM and CLSM technologies are complementary and are more frequently being used to image common biological systems. In order to provide a presentation method that would assist us in evaluating cellular morphology, we propose a simple visualization strategy that is comparative, intuitive, and operates within an open-source environment of ImageJ, SurfaceJ, and VolumeJ applications. In order to find some common ground for AFM-CLSM image comparison, we have developed a plug-in for ImageJ, which allows us to import proprietary image data sets into this application. We propose to represent both AFM and CLSM image data sets as shaded elevation maps with color-coded height. This simple technique utilizes the open source VolumeJ and SurfaceJ plug-ins. To provide an example of this visualization technique, we evaluated the three-dimensional architecture of living chick dorsal root ganglia and sympathetic ganglia measured independently with AFM and CLSM. PMID:15352089

  20. Membrane-based actuation for high-speed single molecule force spectroscopy studies using AFM.

    PubMed

    Sarangapani, Krishna; Torun, Hamdi; Finkler, Ofer; Zhu, Cheng; Degertekin, Levent

    2010-07-01

    Atomic force microscopy (AFM)-based dynamic force spectroscopy of single molecular interactions involves characterizing unbinding/unfolding force distributions over a range of pulling speeds. Owing to their size and stiffness, AFM cantilevers are adversely affected by hydrodynamic forces, especially at pulling speeds >10 microm/s, when the viscous drag becomes comparable to the unbinding/unfolding forces. To circumvent these adverse effects, we have fabricated polymer-based membranes capable of actuating commercial AFM cantilevers at speeds >or=100 microm/s with minimal viscous drag effects. We have used FLUENT, a computational fluid dynamics (CFD) software, to simulate high-speed pulling and fast actuation of AFM cantilevers and membranes in different experimental configurations. The simulation results support the experimental findings on a variety of commercial AFM cantilevers and predict significant reduction in drag forces when membrane actuators are used. Unbinding force experiments involving human antibodies using these membranes demonstrate that it is possible to achieve bond loading rates >or=10(6) pN/s, an order of magnitude greater than that reported with commercial AFM cantilevers and systems. PMID:20054686

  1. Survival of herpes simplex virus type 1 in saliva and tap water contaminating some common objects.

    PubMed

    Bardell, D

    1993-01-01

    Survival at room temperature (21-24 degrees C) of herpes simplex virus type 1 (HSV-1) in saliva on plastic doorknobs and chrome-plated tap handles was investigated. There was no loss of infectious virus before 30 min. Between 30 and 60 min there was a 2-log drop in titre, and infectious virus could still be recovered after 2 h, the longest period tested. The marked drop in titre coincided with drying of the saliva. There was no decline in titre of infectious HSV-1 in a humid atmosphere in which the saliva remained liquid. Similar results were seen with HSV-1 in tap water on tap handles. PMID:8395643

  2. Saliva promotes survival and even proliferation of Candida species in tap water.

    PubMed

    Barbot, Vanessa; Migeot, Virginie; Rodier, Marie-Hélène; Deborde, Marie; Imbert, Christine

    2011-11-01

    Candida yeasts colonize the human oral cavity as commensals or opportunistic pathogens. They may be isolated from water circulating in dental unit waterlines mixed with traces of saliva mainly because of the dysfunction of antiretraction valves. This study deals with the growth ability of Candida albicans, Candida glabrata and Candida parapsilosis in tap water with saliva (0-20% v/v). Results show that C. glabrata is the most susceptible species in tap water. Furthermore, saliva promotes both survival and proliferation of the three studied Candida species in tap water. PMID:22092759

  3. On the Cutting Performance of Coated HSS Taps When Machining of Austenitic Steel

    NASA Astrophysics Data System (ADS)

    Sliwkova, Petra; Piska, Miroslav

    2014-12-01

    The paper deals with a quality of the PVD coated HSS taps when cutting the stainless austenitic chromiumnickel non-stabilized steel DIN 1.4301 (X5CrNi 18-10). The main attention is focused on the analysis of loading (cutting moment, specific energy) of the HSS taps by means of pieso-electrical dynamometer Kistler 9272 and the relation between the quality of duplex and triplex PVD coatings and their effects on the quality of machined thread surfaces and tool life of the taps. The results showed a safe and stabilized cutting with acceptable quality of threads for HSSE with the TiN+TiCN+DLC coating.

  4. Dual-Mode HDAC Prodrug for Covalent Modification and Subsequent Inhibitor Release

    PubMed Central

    2016-01-01

    Histone deacetylase inhibitors (HDACi) target abnormal epigenetic states associated with a variety of pathologies, including cancer. Here, the development of a prodrug of the canonical broad-spectrum HDACi suberoylanilide hydroxamic acid (SAHA) is described. Although hydroxamic acids are utilized universally in the development of metalloenzyme inhibitors, they are considered to be poor pharmacophores with reduced activity in vivo. We developed a prodrug of SAHA by appending a promoiety, sensitive to thiols, to the hydroxamic acid warhead (termed SAHA-TAP). After incubation of SAHA-TAP with an HDAC, the thiol of a conserved HDAC cysteine residue becomes covalently tagged with the promoiety, initiating a cascade reaction that leads to the release of SAHA. Mass spectrometry and enzyme kinetics experiments validate that the cysteine residue is covalently appended with the TAP promoiety. SAHA-TAP demonstrates cytotoxicity activity against various cancer cell lines. This strategy represents an original prodrug design with a dual mode of action for HDAC inhibition. PMID:25974739

  5. Strength by atomic force microscopy (AFM): Molecular dynamics of water layer squeezing on magnesium oxide

    NASA Astrophysics Data System (ADS)

    Kendall, K.; Dhir, Aman; Yong, Chin W.

    2010-11-01

    Localised strength testing of materials is often carried out in an atomic force microscope (AFM), as foreseen by Kelly in his book Strong Solids (Clarendon Press, Oxford, 1966). During AFM indentation experiments, contamination can strongly influence the observed strength and theoretical interpretation of the results is a major problem. Here, we use molecular dynamics computer modelling to describe the contact of NaCl and MgO crystal probes onto surfaces, comparable to an AFM experiment. Clean NaCl gave elastic, brittle behaviour in contact simulations at 300 K, whereas MgO was more plastic, leading to increased toughness. This paper also considers the strength of an oxide substrate contaminated by water molecules and tested by indentation with a pyramidal probe of oxide crystal. Recent theory on the effect of liquid contaminant layers on surface strength has been mainly focussed on Lennard Jones (LJ) molecules with some studies on alcohols and water, described by molecular dynamics, which allows the molecules to be squeezed out as the crystal lattice is deformed. In this work, we have focused on water by studying the forces between a magnesium oxide (MgO) atomic force microscope (AFM) probe and an MgO slab. Force versus separation has been plotted as the AFM probe was moved towards and away from the substrate. Simulation results showed that the water layers could be removed in steps, giving up to four force peaks. The last monolayer of water could not be squeezed out, even at pressures where MgO deformed plastically. Interestingly, with water present, strength was reduced, but more in tensile than compressive measurements. In conclusion, water contaminating the oxide surface in AFM strength testing is structured. Water layer squeezing removal can be predicted by molecular modelling, which may be verified by AFM experiments to show that water can influence the strength of perfect crystals at the nanometre scale.

  6. A software tool for STED-AFM correlative super-resolution microscopy

    NASA Astrophysics Data System (ADS)

    Koho, Sami; Deguchi, Takahiro; Löhmus, Madis; Näreoja, Tuomas; Hänninen, Pekka E.

    2015-03-01

    Multi-modal correlative microscopy allows combining the strengths of several imaging techniques to provide unique contrast. However it is not always straightforward to setup instruments for such customized experiments, as most microscope manufacturers use their own proprietary software, with limited or no capability to interface with other instruments - this makes correlation of the multi-modal data extremely challenging. We introduce a new software tool for simultaneous use of a STimulated Emission Depletion (STED) microscope with an Atomic Force Microscope (AFM). In our experiments, a Leica TCS STED commercial super-resolution microscope, together with an Agilent 5500ilm AFM microscope was used. With our software, it is possible to synchronize the data acquisition between the STED and AFM instruments, as well as to perform automatic registration of the AFM images with the super-resolution STED images. The software was realized in LabVIEW; the registration part was also implemented as an ImageJ script. The synchronization was realized by controlling simple trigger signals, also available in the commercial STED microscope, with a low-cost National Instruments USB-6501 digital I/O card. The registration was based on detecting the positions of the AFM tip inside the STED fieldof-view, which were then used as registration landmarks. The registration should work on any STED and tip-scanning AFM microscope combination, at nanometer-scale precision. Our STED-AFM correlation method has been tested with a variety of nanoparticle and fixed cell samples. The software will be released under BSD open-source license.

  7. A rapid and automated relocation method of an AFM probe for high-resolution imaging.

    PubMed

    Zhou, Peilin; Yu, Haibo; Shi, Jialin; Jiao, Niandong; Wang, Zhidong; Wang, Yuechao; Liu, Lianqing

    2016-09-30

    The atomic force microscope (AFM) is one of the most powerful tools for high-resolution imaging and high-precision positioning for nanomanipulation. The selection of the scanning area of the AFM depends on the use of the optical microscope. However, the resolution of an optical microscope is generally no larger than 200 nm owing to wavelength limitations of visible light. Taking into consideration the two determinants of relocation-relative angular rotation and positional offset between the AFM probe and nano target-it is therefore extremely challenging to precisely relocate the AFM probe to the initial scan/manipulation area for the same nano target after the AFM probe has been replaced, or after the sample has been moved. In this paper, we investigate a rapid automated relocation method for the nano target of an AFM using a coordinate transformation. The relocation process is both simple and rapid; moreover, multiple nano targets can be relocated by only identifying a pair of reference points. It possesses a centimeter-scale location range and nano-scale precision. The main advantages of this method are that it overcomes the limitations associated with the resolution of optical microscopes, and that it is label-free on the target areas, which means that it does not require the use of special artificial markers on the target sample areas. Relocation experiments using nanospheres, DNA, SWCNTs, and nano patterns amply demonstrate the practicality and efficiency of the proposed method, which provides technical support for mass nanomanipulation and detection based on AFM for multiple nano targets that are widely distributed in a large area. PMID:27559679

  8. TAp63gamma is required for the late stages of myogenesis

    PubMed Central

    Cefalù, S; Lena, AM; Vojtesek, B; Musarò, A; Rossi, A; Melino, G; Candi, E

    2015-01-01

    p53 family members, p63 and p73, play a role in controlling early stage of myogenic differentiation. We demonstrated that TAp63gamma, unlike the other p53 family members, is markedly up-regulated during myogenic differentiation in murine C2C7 cell line. We also found that myotubes formation was inhibited upon TAp63gamma knock-down, as also indicated by atrophyic myotubes and reduction of myoblasts fusion index. Analysis of TAp63gamma-dependend transcripts identified several target genes involved in skeletal muscle contractility energy metabolism, myogenesis and skeletal muscle autocrine signaling. These results indicate that TAp63gamma is a late marker of myogenic differentiation and, by controlling different sub-sets of target genes, it possibly contributes to muscle growth, remodeling, functional differentiation and tissue homeostasis. PMID:25790093

  9. Tapping of Love waves in an isotropic surface waveguide by surface-to-bulk wave transduction.

    NASA Technical Reports Server (NTRS)

    Tuan, H.-S.; Chang, C.-P.

    1972-01-01

    A theoretical study of tapping a Love wave in an isotropic microacoustic surface waveguide is given. The surface Love wave is tapped by partial transduction into a bulk wave at a discontinuity. It is shown that, by careful design of the discontinuity, the converted bulk wave power and the radiation pattern may be controlled. General formulas are derived for the calculation of these important characteristics from a relatively general surface contour deformation.

  10. Digital tapped delay lines for HWIL testing of matched filter radar receivers

    NASA Astrophysics Data System (ADS)

    Olson, Richard F.; Braselton, William J.; Mohlere, Richard D.

    2009-05-01

    Matched filter processing for pulse compression of phase coded waveforms is a classic method for increasing radar range measurement resolution. A generic approach for simulating high resolution range extended radar scenes in a Hardware in the Loop (HWIL) test environment is to pass the phase coded radar transmit pulse through an RF tapped delay line comprised of individually amplitude- and phase-weighted output taps. In the generic approach, the taps are closely spaced relative to time intervals equivalent to the range resolution of the compressed radar pulse. For a range-extended high resolution clutter scene, the increased number of these taps can make an analog implementation of an RF tapped delay system impractical. Engineers at the U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) have addressed this problem by transferring RF tapped delay line signal operations to the digital domain. New digital tapped delay line (DTDL) systems have been designed and demonstrated which are physically compact compared to analog RF TDLs, leverage low cost FPGA and data converter technology, and may be readily expanded using open slots in a VME card cage. In initial HWIL applications, the new DTDLs have been shown to produce better dynamic range in pulse compressed range profiles than their analog TDL predecessors. This paper describes the signal requirements and system architecture for digital tapped delay lines. Implementation, performance, and HWIL simulation integration issues for AMRDEC's first generation DTDLs are addressed. The paper concludes with future requirements and plans for ongoing DTDL technology development at AMRDEC.

  11. Lessons from the TAPS study - communication failures between hospitals and general practices.

    PubMed

    Makeham, Meredith A B; Mira, Michael; Kidd, Michael R

    2008-09-01

    The Threats to Australian Patient Safety (TAPS) study collected 648 anonymous reports about threats to patient safety from a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened and would not want to happen again, regardless of who was at fault or the outcome of the event. This series of articles presents clinical lessons resulting from the TAPS study. PMID:18797522

  12. Lessons from the TAPS study - reducing the risk of patient harm.

    PubMed

    Makeham, Meredith A B; Stromer, Simone; Kidd, Michael R

    2008-05-01

    The Threats to Australian Patient Safety (TAPS) Study collected 648 anonymous reports about threats to patient safety from a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened and would not want to happen again, regardless of who was at fault or the outcome of the event. This series of articles presents clinical lessons resulting from the TAPS study. PMID:18464963

  13. Lessons from the TAPS study. Warfarin: a major cause of threats to patient safety.

    PubMed

    Makeham, Meredith A B; Saltman, Deborah C; Kidd, Michael R

    2008-10-01

    The Threats to Australian Patient Safety (TAPS) study collected 648 anonymous reports about threats to patient safety from a representative random sample of Australian general practitioners. These contained any events the GPs felt should not have happened, and would not want to happen again, regardless of who was at fault or the outcome of the event. This series of articles presents clinical lessons resulting from the TAPS study. PMID:19002300

  14. Establishing Tap Reliability in Expert Witness Testimony: Using Scenarios to Identify Calibration Needs

    SciTech Connect

    Endicott-Popovsky, Barbara E.; Fluckiger, Jerry D.; Frincke, Deborah A.

    2007-04-26

    In this paper we expand work initially described in calibrating low-level network taps, where we used examples of how one might establish the degree of soundness for network data gathering devices, using low-level tap calibration as our example. Our approach in this paper is adapted from Weismann's Flaw Hypothesis Methodology for penetration testing design, and extends the earlier work by considering a broader range of typical misuse and attack scenarios, again with respect to lower layer network devices.

  15. Efficacy of Niclosamide as a potential topical antipenetrant (TAP) against cercariae of Schistosoma mansoni in monkeys.

    PubMed

    Bruce, J I; Miller, R; Lightner, L; Yoganathan, S

    1992-01-01

    A 1% (W/V) formulation of Niclosamide (2', 5-Dichloro-4-nitrosalicylanilide) (TAP) was tested on Cebus apella monkeys as a topical prophylactic against schistosomiasis mansoni. Two experiments were conducted using the same formulation. In the first experiment, the TAP provided complete protection against schistosomiasis for 3 days. Of the 4 monkeys treated with TAP 7 days before exposure to Schistosoma mansoni cercariae, 2 were completely protected. The remaining 2 monkeys of the 7 day treatment group had a 78% or greater reduction in adult worm burdens when compared to the placebo treated monkeys. The second experiment was designed to determine the time between day 3 and 7 when the TAP no longer provided complete protection. However, all of the TAP treated monkeys in this experiment were completely protected, even the monkeys treated 7 days earlier. In both experiments, all monkeys used as infection controls and those receiving only the placebo became infected and showed typical experimental schistosomiasis. These results demonstrate that the TAP could provide fast acting, short-term protection to people who must enter cercariae infested water. PMID:1343909

  16. p53 and TAp63 Promote Keratinocyte Proliferation and Differentiation in Breeding Tubercles of the Zebrafish

    PubMed Central

    Fischer, Boris; Metzger, Manuel; Richardson, Rebecca; Knyphausen, Philipp; Ramezani, Thomas; Franzen, Rainer; Schmelzer, Elmon; Bloch, Wilhelm; Carney, Thomas J.; Hammerschmidt, Matthias

    2014-01-01

    p63 is a multi-isoform member of the p53 family of transcription factors. There is compelling genetic evidence that ΔNp63 isoforms are needed for keratinocyte proliferation and stemness in the developing vertebrate epidermis. However, the role of TAp63 isoforms is not fully understood, and TAp63 knockout mice display normal epidermal development. Here, we show that zebrafish mutants specifically lacking TAp63 isoforms, or p53, display compromised development of breeding tubercles, epidermal appendages which according to our analyses display more advanced stratification and keratinization than regular epidermis, including continuous desquamation and renewal of superficial cells by derivatives of basal keratinocytes. Defects are further enhanced in TAp63/p53 double mutants, pointing to partially redundant roles of the two related factors. Molecular analyses, treatments with chemical inhibitors and epistasis studies further reveal the existence of a linear TAp63/p53->Notch->caspase 3 pathway required both for enhanced proliferation of keratinocytes at the base of the tubercles and their subsequent differentiation in upper layers. Together, these studies identify the zebrafish breeding tubercles as specific epidermal structures sharing crucial features with the cornified mammalian epidermis. In addition, they unravel essential roles of TAp63 and p53 to promote both keratinocyte proliferation and their terminal differentiation by promoting Notch signalling and caspase 3 activity, ensuring formation and proper homeostasis of this self-renewing stratified epithelium. PMID:24415949

  17. Sub-surface imaging of carbon nanotube-polymer composites using dynamic AFM methods.

    PubMed

    Cadena, Maria J; Misiego, Rocio; Smith, Kyle C; Avila, Alba; Pipes, Byron; Reifenberger, Ron; Raman, Arvind

    2013-04-01

    High-resolution sub-surface imaging of carbon nanotube (CNT) networks within polymer nanocomposites is demonstrated through electrical characterization techniques based on dynamic atomic force microscopy (AFM). We compare three techniques implemented in the single-pass configuration: DC-biased amplitude modulated AFM (AM-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) in terms of the physics of sub-surface image formation and experimental robustness. The methods were applied to study the dispersion of sub-surface networks of single-walled nanotubes (SWNTs) in a polyimide (PI) matrix. We conclude that among these methods, the KPFM channel, which measures the capacitance gradient (∂C/∂d) at the second harmonic of electrical excitation, is the best channel to obtain high-contrast images of the CNT network embedded in the polymer matrix, without the influence of surface conditions. Additionally, we propose an analysis of the ∂C/∂d images as a tool to characterize the dispersion and connectivity of the CNTs. Through the analysis we demonstrate that these AFM-based sub-surface methods probe sufficiently deep within the SWNT composites, to resolve clustered networks that likely play a role in conductivity percolation. This opens up the possibility of dynamic AFM-based characterization of sub-surface dispersion and connectivity in nanostructured composites, two critical parameters for nanocomposite applications in sensors and energy storage devices. PMID:23478510

  18. Enabling accurate gate profile control with inline 3D-AFM

    NASA Astrophysics Data System (ADS)

    Bao, Tianming; Lopez, Andrew; Dawson, Dean

    2009-05-01

    The logic and memory semiconductor device technology strives to follow the aggressive ITRS roadmap. The ITRS calls for increased 3D metrology to meet the demand for tighter process control at 45nm and 32nm nodes. In particular, gate engineering has advanced to a level where conventional metrology by CD-SEM and optical scatterometry (OCD) faces fundamental limitations without involvement of 3D atomic force microscope (3D-AFM or CD-AFM). This paper reports recent progress in 3D-AFM to address the metrology need to control gate dimension in MOSFET transistor formation. 3D-AFM metrology measures the gate electrode at post-etch with the lowest measurement uncertainty for critical gate geometry, including linewidth, sidewall profile, sidewall angle (SWA), line width roughness (LWR), and line edge roughness (LER). 3D-AFM enables accurate gate profile control in three types of metrology applications: reference metrology to validate CD-SEM and OCD, inline depth or 3D monitoring, or replacing TEM for 3D characterization for engineering analysis.

  19. Development of a new generation of active AFM tools for applications in liquids

    NASA Astrophysics Data System (ADS)

    Rollier, A.-S.; Jenkins, D.; Dogheche, E.; Legrand, B.; Faucher, M.; Buchaillot, L.

    2010-08-01

    Atomic force microscopy (AFM) is a powerful imaging tool with high-resolution imaging capability. AFM probes consist of a very sharp tip at the end of a silicon cantilever that can respond to surface artefacts to produce an image of the topography or surface features. They are intrinsically passive devices. For imaging soft biological samples, and also for samples in liquid, it is essential to control the AFM tip position, both statically and dynamically, and this is not possible using external actuators mounted on the AFM chip. AFM cantilevers have been fabricated using silicon micromachining to incorporate a piezoelectric thin film actuator for precise control. The piezoelectric thin films have been fully characterized to determine their actuation performance and to characterize the operation of the integrated device. Examples of the spatial and vertical response are presented to illustrate their imaging capability. For operation in a liquid environment, the dynamic behaviour has been modelled and verified experimentally. The optimal drive conditions for the cantilever, along with their dynamic response, including frequency and phase in air and water, are presented.

  20. Effect of AFM probe geometry on visco-hyperelastic characterization of soft materials.

    PubMed

    Boccaccio, Antonio; Lamberti, Luciano; Papi, Massimiliano; De Spirito, Marco; Pappalettere, Carmine

    2015-08-14

    Atomic force microscopy (AFM) nanoindentation is very suited for nano- and microscale mechanical characterization of soft materials. Although the structural response of polymeric networks that form soft matter depends on viscous effects caused by the relative slippage of polymeric chains, the usual assumption made in the AFM-based characterization is that the specimen behaves as a purely elastic material and viscous forces are negligible. However, for each geometric configuration of the AFM tip, there will be a limit indentation rate above which viscous effects must be taken into account to correctly determine mechanical properties. A parametric finite element study conducted on 12 geometric configurations of a blunt cone AFM tip (overall, the study included about 200 finite element analyses) allowed us to determine the limit indentation rate for each configuration. The selected tip dimensions cover commercially available products and account for changes in tip geometry caused by serial measurements. Nanoindentation rates cover typical experimental conditions set in AFM bio-measurements on soft matter. Viscous effects appear to be more significant in the case of sharper tips. This implies that, if quantitative data on sample viscosity are not available, using a rounded indenter and carrying out experiments below the limit indentation rate will allow errors in the determination of mechanical properties to be minimized. PMID:26201503

  1. AFM1 in Milk: Physical, Biological, and Prophylactic Methods to Mitigate Contamination

    PubMed Central

    Giovati, Laura; Magliani, Walter; Ciociola, Tecla; Santinoli, Claudia; Conti, Stefania; Polonelli, Luciano

    2015-01-01

    Aflatoxins (AFs) are toxic, carcinogenic, immunosuppressive secondary metabolites produced by some Aspergillus species which colonize crops, including many dietary staple foods and feed components. AFB1 is the prevalent and most toxic among AFs. In the liver, it is biotransformed into AFM1, which is then excreted into the milk of lactating mammals, including dairy animals. AFM1 has been shown to be cause of both acute and chronic toxicoses. The presence of AFM1 in milk and dairy products represents a worldwide concern since even small amounts of this metabolite may be of importance as long-term exposure is concerned. Contamination of milk may be mitigated either directly, decreasing the AFM1 content in contaminated milk, or indirectly, decreasing AFB1 contamination in the feed of dairy animals. Current strategies for AFM1 mitigation include good agricultural practices in pre-harvest and post-harvest management of feed crops (including storage) and physical or chemical decontamination of feed and milk. However, no single strategy offers a complete solution to the issue. PMID:26512694

  2. Mode-synthesizing atomic force microscopy for volume characterization of mixed metal nanoparticles.

    PubMed

    Vitry, P; Bourillot, E; Tétard, L; Plassard, C; Lacroute, Y; Lesniewska, E

    2016-09-01

    Atomic force microscopy (AFM) and other techniques derived from AFM have revolutionized the understanding of materials and biology at the nanoscale, but mostly provide surface properties. The observation of subsurface nanoscale features and properties remains a great challenge in nanometrology. The operating principle of the mode-synthesizing AFM (MSAFM) is based on the interaction of two ultrasonic waves, one launched by the AFM probe fp , a second launched by the sample fs , and their resulting nonlinear frequency mixing. Recent developments highlighted the need for quantitative correlation between the role of the frequency actuation of the probe fp and the sample fs . Here we present the great potential of MSAFM for advanced volume characterization of metallic nanoparticles presenting a multilayered structure composed of a nickel core surrounded by a gold envelope. PMID:27018572

  3. Evaluation of the electrical contact area in contact-mode scanning probe microscopy

    SciTech Connect

    Celano, Umberto E-mail: u.celano@gmail.com; Chintala, Ravi Chandra; Vandervorst, Wilfried; Hantschel, Thomas; Giammaria, Guido; Conard, Thierry; Bender, Hugo

    2015-06-07

    The tunneling current through an atomic force microscopy (AFM) tip is used to evaluate the effective electrical contact area, which exists between tip and sample in contact-AFM electrical measurements. A simple procedure for the evaluation of the effective electrical contact area is described using conductive atomic force microscopy (C-AFM) in combination with a thin dielectric. We characterize the electrical contact area for coated metal and doped-diamond tips operated at low force (<200 nN) in contact mode. In both cases, we observe that only a small fraction (<10 nm{sup 2}) of the physical contact (∼100 nm{sup 2}) is effectively contributing to the transport phenomena. Assuming this reduced area is confined to the central area of the physical contact, these results explain the sub-10 nm electrical resolution observed in C-AFM measurements.

  4. Evaluation of the electrical contact area in contact-mode scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Celano, Umberto; Hantschel, Thomas; Giammaria, Guido; Chintala, Ravi Chandra; Conard, Thierry; Bender, Hugo; Vandervorst, Wilfried

    2015-06-01

    The tunneling current through an atomic force microscopy (AFM) tip is used to evaluate the effective electrical contact area, which exists between tip and sample in contact-AFM electrical measurements. A simple procedure for the evaluation of the effective electrical contact area is described using conductive atomic force microscopy (C-AFM) in combination with a thin dielectric. We characterize the electrical contact area for coated metal and doped-diamond tips operated at low force (<200 nN) in contact mode. In both cases, we observe that only a small fraction (<10 nm2) of the physical contact (˜100 nm2) is effectively contributing to the transport phenomena. Assuming this reduced area is confined to the central area of the physical contact, these results explain the sub-10 nm electrical resolution observed in C-AFM measurements.

  5. The guardians of the genome (p53, TA-p73, and TA-p63) are regulators of tumor suppressor miRNAs network.

    PubMed

    Boominathan, Lakshmanane

    2010-12-01

    The tumor suppressor p53 homologues, TA-p73, and p63 have been shown to function as tumor suppressors. However, how they function as tumor suppressors remains elusive. Here, I propose a number of tumor suppressor pathways that illustrate how the TA-p73 and p63 could function as negative regulators of invasion, metastasis, and cancer stem cells (CSCs) proliferation. Furthermore, I provide molecular insights into how TA-p73 and p63 could function as tumor suppressors. Remarkably, the guardians--p53, p73, and p63--of the genome are in control of most of the known tumor suppressor miRNAs, tumor suppressor genes, and metastasis suppressors by suppressing c-myc through miR-145/let-7/miR-34/TRIM32/PTEN/FBXW7. In particular, p53 and TA-p73/p63 appear to upregulate the expression of (1) tumor suppressor miRNAs, such as let-7, miR-34, miR-15/16a, miR-145, miR-29, miR-26, miR-30, and miR-146a; (2) tumor suppressor genes, such as PTEN, RBs, CDKN1a/b/c, and CDKN2a/b/c/d; (3) metastasis suppressors, such as Raf kinase inhibitory protein, CycG2, and DEC2, and thereby they enlarge their tumor suppressor network to inhibit tumorigenesis, invasion, angiogenesis, migration, metastasis, and CSCs proliferation. PMID:20922462

  6. Quality comparison of tap water vs. bottled water in the industrial city of Yanbu (Saudi Arabia).

    PubMed

    Ahmad, Maqbool; Bajahlan, Ahmad S

    2009-12-01

    This study was conducted to compare the quality of bottled water with potabilized desalinated tap water. Fourteen brands of local and imported bottled water samples were collected from the local market and analyzed for physicochemical parameters in the Royal Commission Environmental Laboratory. Results were compared with 5-year continuous monitoring data of tap water from different locations in Madinat Yanbu Al-Sinaiyah (MYAS) including storage tanks of desalination plant. Results show that there was no significant difference in the quality of tap water and bottled water. Bacteriological test was never found positive in the 5-year data in tap water. Similarly, physicochemical analysis shows the persistent quality of tap water. Based on hardness analysis, bottled and tap water are categorized as soft water. Trihalomethanes (THMs) study also indicates that traces of disinfection by products (DBPs) are present in both tap and bottled water and are much less than the World Health Organization and Environmental Protection Agency maximum permissible limits. It is also important to note that the tap water distribution network in MAYS is a high-pressure recirculation network and there is no chance to grow bacteria in stagnant water in pipe lines or houses. Recently, the Royal Commission has replaced the whole drinking water network, which was made of asbestos-cemented pipes with glass-reinforced plastic (GRP) pipes, to avoid any asbestos contaminations. Based on these results, it is concluded that drinking water distributed in the city is of very good and persistent quality, comparable with bottled water. Continuous monitoring also guarantees the safe drinking water to the community. Hence, it is the responsibility of the Royal Commission to encourage the peoples in the city to drink tap water as it is as good as bottled water even better than some of the brands and is monitored regularly. It is also much cheaper compared to bottled water and is available round the clock

  7. Polo-like kinase 2 acting as a promoter in human tumor cells with an abundance of TAp73

    PubMed Central

    Hu, ZhengBo; Xu, ZunYing; Liao, XiaoHong; Yang, Xiao; Dong, Cao; Luk, KuaDi; Jin, AnMin; Lu, Hai

    2015-01-01

    Background TAp73, a member of the p53 tumor suppressor family, is frequently overexpressed in malignant tumors in humans. TAp73 abundance and phosphorylation modification result in variations in transcriptional activity. In a previous study, we found that the antitumor function of TAp73 was reactivated by dephosphorylation in head and neck squamous cell carcinomas. Polo-like kinase 2 (PLK2) displayed a close relationship with the p53 family in affecting the fate of cells. Herein, we investigate the hypothesis that PLK2 phosphorylates TAp73 and inhibits TAp73 function. Materials and methods Head and neck squamous cell carcinoma cell lines and osteosarcoma cell lines were used as natural models of the different expression levels of TAp73. Phosphorylation predictor software Scansite 3.0 and the predictor GPS-polo 1.0 were used to analyze the phosphorylation sites. Coimmunoprecipitation, phosphor-tag Western blot, metabolic labeling, and indirect immunofluorescence assays were used to determine the interactions between PLK2 and TAp73. TAp73 activity was assessed by Western blot and reverse transcription polymerase chain reaction, which we used to detect P21 and PUMA, both downstream genes of TAp73. The physiological effects of PLK2 cross talk with TAp73 on cell cycle progress and apoptosis were observed by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling assays. Results PLK2 binds to and phosphorylates TAp73. PLK2 phosphorylates TAp73 at residue Ser48 and prohibits TAp73 translocation to the nucleus. Additionally, PLK2 inhibition combined with a DNA-damaging drug upregulated p21 and PUMA mRNA expression to a greater extent than DNA-damaging drug treatment alone. Inhibiting PLK2 in TAp73-enriched cells strengthened the effects of the DNA-damaging drug on both G1 phase arrest and apoptosis. Pretreatment with TAp73-siRNA weakened these effects. Conclusion These findings reveal a novel PLK2 function (catalyzed phosphorylation of TAp73) which

  8. AFM-based force spectroscopy measurements of mature amyloid fibrils of the peptide glucagon

    NASA Astrophysics Data System (ADS)

    Dong, Mingdong; Bruun Hovgaard, Mads; Mamdouh, Wael; Xu, Sailong; Otzen, Daniel Erik; Besenbacher, Flemming

    2008-09-01

    We report on the mechanical characterization of individual mature amyloid fibrils by atomic force microscopy (AFM) and AFM-based single-molecule force spectroscopy (SMFS). These self-assembling materials, formed from the 29-residue amphiphatic peptide hormone glucagon, were found to display a reversible elastic behaviour. Based on AFM morphology and SMFS studies, we suggest that the observed elasticity is due to a force-induced conformational transition which is reversible due to the β-helical conformation of protofibrils, allowing a high degree of extension. The elastic properties of such mature fibrils contribute to their high stability, suggesting that the internal hydrophobic interactions of amyloid fibrils are likely to be of fundamental importance in the assembly of amyloid fibrils and therefore for the understanding of the progression of their associated pathogenic disorders. In addition, such biological amyloid fibril structures with highly stable mechanical properties can potentially be used to produce nanofibres (nanowires) that may be suitable for nanotechnological applications.

  9. AFM-assisted fabrication of thiol SAM pattern with alternating quantified surface potential

    PubMed Central

    2011-01-01

    Thiol self-assembled monolayers (SAMs) are widely used in many nano- and bio-technology applications. We report a new approach to create and characterize a thiol SAMs micropattern with alternating charges on a flat gold-coated substrate using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We produced SAMs-patterns made of alternating positively charged, negatively charged, and hydrophobic-terminated thiols by an automated AFM-assisted manipulation, or nanografting. We show that these thiol patterns possess only small topographical differences as revealed by AFM, and distinguished differences in surface potential (20-50 mV), revealed by KPFM. The pattern can be helpful in the development of biosensor technologies, specifically for selective binding of biomolecules based on charge and hydrophobicity, and serve as a model for creating surfaces with quantified alternating surface potential distribution. PMID:21711703

  10. A sub-50 nm three-step height sample for AFM calibration

    NASA Astrophysics Data System (ADS)

    Yang, Shuming; Li, Changsheng; Wang, Chenying; Jiang, Zhuangde

    2014-12-01

    In this paper, a sub-50 nm three-step height sample was made for vertical calibration of atomic force microscopy (AFM) and a new step height evaluation algorithm based on polynomial fitting is discussed. The influences of AFM artefacts such as particles, image bow and high-order errors on step height were studied. The experimental results showed that the polynomial order p2 and threshold t were not critical factors. However, the increment Δh and the polynomial order p used in the calculation of optimal shifting distance were important and must be carefully considered. Δh = 0.1 nm and p ≥ 4 were determined to get a stable step height. The sample had small roughness and good uniformity. It has the potential to serve as a high quality step height standard sample for AFM calibration.

  11. Review and perspectives of AFM application on the study of deformable drop/bubble interactions.

    PubMed

    Wang, Wei; Li, Kai; Ma, Mengyu; Jin, Hang; Angeli, Panagiota; Gong, Jing

    2015-11-01

    The applications of Atomic Force Microscopy (AFM) on the study of dynamic interactions and film drainage between deformable bodies dispersed in aqueous solutions are reviewed in this article. Novel experimental designs and recent advances in experimental methodologies are presented, which show the advantage of using AFM as a tool for probing colloidal interactions. The effects of both DLVO and non-DLVO forces on the colloid stabilization mechanism are discussed. Good agreement is found between the force - drop/bubble deformation behaviour revealed by AFM measurements and the theoretical modeling of film drainage process, giving a convincing explanation of the occurrence of certain phenomenon. However, the behaviour and shape of deformable drops as they approach or retract is still not well resolved. In addition, when surfactants are present further research is needed on the absorption of surfactant molecules into the interfaces, their mobility and the effects on interfacial film properties. PMID:26344865

  12. Imaging and force measurement of LDL and HDL by AFM in air and liquid

    PubMed Central

    Gan, Chaoye; Ao, Meiying; Liu, Zhanghua; Chen, Yong

    2015-01-01

    The size and biomechanical properties of lipoproteins are tightly correlated with their structures/functions. While atomic force microscopy (AFM) has been used to image lipoproteins the force measurement of these nano-sized particles is missing. We detected that the sizes of LDL and HDL in liquid are close to the commonly known values. The Young’s modulus of LDL or HDL is ∼0.4 GPa which is similar to that of some viral capsids or nanovesicles but greatly larger than that of various liposomes. The adhesive force of LDL or HDL is small (∼200 pN). The comparison of AFM detection in air and liquid was also performed which is currently lacking. Our data may provide useful information for better understanding and AFM detection of lipoproteins. PMID:25893163

  13. Mapping site-specific endonuclease binding to DNA by direct imaging with AFM

    SciTech Connect

    Allison, D.P.; Thundat, T.; Doktycz, M.J.; Kerper, P.S.; Warmack, R.J.; Modrich, P.; Isfort, R.J.

    1995-12-31

    Physical mapping of DNA can be accomplished by direct AFM imaging of site specific proteins bound to DNA molecules. Using Gln-111, a mutant of EcoRI endonuclease with a specific affinity for EcoRI sites 1,000 times greater than wild type enzyme but with cleavage rate constants reduced by a factor of 10{sup 4}, the authors demonstrate site-specific mapping by direct AFM imaging. Images are presented showing specific-site binding of Gln-111 to plasmids having either one (pBS{sup +}) or two (pMP{sup 32}) EcoRI sites. Identification of the Gln-111/DNA complex is greatly enhanced by biotinylation of the complex followed by reaction with streptavidin gold prior to imaging. Image enhancement coupled with improvements in the preparation techniques for imaging large DNA molecules, such as lambda DNA (47 kb), has the potential to contribute to direct AFM restriction mapping of cosmid-sized genomic DNAs.

  14. Multiparametric high-resolution imaging of native proteins by force-distance curve-based AFM.

    PubMed

    Pfreundschuh, Moritz; Martinez-Martin, David; Mulvihill, Estefania; Wegmann, Susanne; Muller, Daniel J

    2014-05-01

    A current challenge in the life sciences is to understand how the properties of individual molecular machines adjust in order to meet the functional requirements of the cell. Recent developments in force-distance (FD) curve-based atomic force microscopy (FD-based AFM) enable researchers to combine sub-nanometer imaging with quantitative mapping of physical, chemical and biological properties. Here we present a protocol to apply FD-based AFM to the multiparametric imaging of native proteins under physiological conditions. We describe procedures for experimental FD-based AFM setup, high-resolution imaging of proteins in the native unperturbed state with simultaneous quantitative mapping of multiple parameters, and data interpretation and analysis. The protocol, which can be completed in 1-3 d, enables researchers to image proteins and protein complexes in the native unperturbed state and to simultaneously map their biophysical and biochemical properties at sub-nanometer resolution. PMID:24743419

  15. AFM characterization of nonwoven material functionalized by ZnO sputter coating

    SciTech Connect

    Deng Bingyao; Yan Xiong; Wei Qufu Gao Weidong

    2007-10-15

    Sputter coatings provide new approaches to the surface functionalization of textile materials. In this study, polyethylene terephthalate (PET) nonwoven material was used as a substrate for creating functional nanostructures on the fiber surfaces. A magnetron sputter coating was used to deposit functional zinc oxide (ZnO) nanostructures onto the nonwoven substrate. The evolution of the surface morphology of the fibers in the nonwoven web was examined using atomic force microscopy (AFM). The AFM observations revealed a significant difference in the morphology of the fibers before and after the sputter coating. The AFM images also indicated the effect of the sputtering conditions on the surface morphology of the fibers. The increase in the sputtering time led to the growth of the ZnO grains on the fiber surfaces. The higher pressure in the sputtering chamber could cause the formation of larger grains on the fiber surfaces. The higher power used also generated larger grains on the fiber surfaces.

  16. High precision attachment of silver nanoparticles on AFM tips by dielectrophoresis.

    PubMed

    Leiterer, Christian; Wünsche, Erik; Singh, Prabha; Albert, Jens; Köhler, Johann M; Deckert, Volker; Fritzsche, Wolfgang

    2016-05-01

    AFM tips are modified with silver nanoparticles using an AC electrical field. The used technique works with sub-micron precision and also does not require chemical modification of the tip. Based on the electrical parameters applied in the process, particle density and particle position on the apex of the tip can be adjusted. The feasibility of the method is proven by subsequent tip-enhanced Raman spectroscopy (TERS) measurements using the fabricated tips as a measurement probe. Since this modification process itself does not require any lithographic processing, the technique can be easily adapted to modify AFM tips with a variety of nanostructures with pre-defined properties, while being parallelizable for a potential commercial application. Graphical abstract Silver nanoparticles attached to AFM tips using dielectrophoresis. Comparing nanoparticles attached using 1 kHz (left) to 1 MHz (right), SEM and optical (inset) images. PMID:26968565

  17. Tor proteins and protein phosphatase 2A reciprocally regulate Tap42 in controlling cell growth in yeast.

    PubMed Central

    Jiang, Y; Broach, J R

    1999-01-01

    Tor proteins, homologous to DNA-dependent protein kinases, participate in a signal transduction pathway in yeast that regulates protein synthesis and cell wall expansion in response to nutrient availability. The anti-inflammatory drug rapamycin inhibits yeast cell growth by inhibiting Tor protein signaling. This leads to diminished association of a protein, Tap42, with two different protein phosphatase catalytic subunits; one encoded redundantly by PPH21 and PPH22, and one encoded by SIT4. We show that inactivation of either Cdc55 or Tpd3, which regulate Pph21/22 activity, results in rapamycin resistance and that this resistance correlates with an increased association of Tap42 with Pph21/22. Furthermore, we show Tor-dependent phosphorylation of Tap42 both in vivo and in vitro and that this phosphorylation is rapamycin sensitive. Inactivation of Cdc55 or Tpd3 enhances in vivo phosphorylation of Tap42. We conclude that Tor phosphorylates Tap42 and that phosphorylated Tap42 effectively competes with Cdc55/Tpd3 for binding to the phosphatase 2A catalytic subunit. Furthermore, Cdc55 and Tpd3 promote dephosphorylation of Tap42. Thus, Tor stimulates growth-promoting association of Tap42 with Pph21/22 and Sit4, while Cdc55 and Tpd3 inhibit this association both by direct competition and by dephosphorylation of Tap42. These results establish Tap42 as a target of Tor and add further refinement to the Tor signaling pathway. PMID:10329624

  18. MEMS piezoresistive ring resonator for AFM imaging with pico-Newton force resolution

    NASA Astrophysics Data System (ADS)

    Xiong, Z.; Walter, B.; Mairiaux, E.; Faucher, M.; Buchaillot, L.; Legrand, B.

    2013-03-01

    A new concept of atomic force microscope (AFM) oscillating probes using electrostatic excitation and piezoresistive detection is presented. The probe is characterized by electrical methods in vacuum and by mechanical methods in air. A frequency-mixing measurement technique is developed to reduce the parasitic signal floor. The probe resonance frequencies are in the 1 MHz range and the quality factor is measured about 53 000 in vacuum and 3000 in air. The ring probe is mounted onto a commercial AFM set-up and topographic images of patterned sample surfaces are obtained. The force resolution deduced from the measurements is about 10 pN Hz-0.5.

  19. Coexistence of orbital and CE-AFM orders in colossal magnetoresistance manganites: A symmetry perspective

    NASA Astrophysics Data System (ADS)

    Ribeiro, J. L.

    2016-07-01

    The complex interplay between order parameters of different nature that dominates the physics of colossal magnetoresistance manganites is analysed from a symmetry based perspective. Phenomenological energies are given for the different competing phases. It is shown that the general trends observed in different systems, such as the mutual exclusion of orbital order and A-AFM order and the related stabilization of the CE-AFM order, stem to large extend from the symmetry of the parameters involved. The possible stabilization of complex phases where charge and orbital order coexist with magnetic and ferroelectric states is also anticipated.

  20. FRAME (Force Review Automation Environment): MATLAB-based AFM data processor.

    PubMed

    Partola, Kostyantyn R; Lykotrafitis, George

    2016-05-01

    Data processing of force-displacement curves generated by atomic force microscopes (AFMs) for elastic moduli and unbinding event measurements is very time consuming and susceptible to user error or bias. There is an evident need for consistent, dependable, and easy-to-use AFM data processing software. We have developed an open-source software application, the force review automation environment (or FRAME), that provides users with an intuitive graphical user interface, automating data processing, and tools for expediting manual processing. We did not observe a significant difference between manually processed and automatically processed results from the same data sets. PMID:26972765

  1. Direct visualization of the trimeric structure of the ASIC1a channel, using AFM imaging

    SciTech Connect

    Carnally, Stewart M.; Dev, Harveer S.; Stewart, Andrew P.; Barrera, Nelson P.; Van Bemmelen, Miguel X.; Schild, Laurent; Henderson, Robert M.; Edwardson, J.Michael

    2008-08-08

    There has been confusion about the subunit stoichiometry of the degenerin family of ion channels. Recently, a crystal structure of acid-sensing ion channel (ASIC) 1a revealed that it assembles as a trimer. Here, we used atomic force microscopy (AFM) to image unprocessed ASIC1a bound to mica. We detected a mixture of subunit monomers, dimers and trimers. In some cases, triple-subunit clusters were clearly visible, confirming the trimeric structure of the channel, and indicating that the trimer sometimes disaggregated after adhesion to the mica surface. This AFM-based technique will now enable us to determine the subunit arrangement within heteromeric ASICs.

  2. Multiparametric imaging of biological systems by force-distance curve-based AFM.

    PubMed

    Dufrêne, Yves F; Martínez-Martín, David; Medalsy, Izhar; Alsteens, David; Müller, Daniel J

    2013-09-01

    A current challenge in the life sciences is to understand how biological systems change their structural, biophysical and chemical properties to adjust functionality. Addressing this issue has been severely hampered by the lack of methods capable of imaging biosystems at high resolution while simultaneously mapping their multiple properties. Recent developments in force-distance (FD) curve-based atomic force microscopy (AFM) now enable researchers to combine (sub)molecular imaging with quantitative mapping of physical, chemical and biological interactions. Here we discuss the principles and applications of advanced FD-based AFM tools for the quantitative multiparametric characterization of complex cellular and biomolecular systems under physiological conditions. PMID:23985731

  3. Probing the PEDOT:PSS/cell interface with conductive colloidal probe AFM-SECM

    NASA Astrophysics Data System (ADS)

    Knittel, P.; Zhang, H.; Kranz, C.; Wallace, G. G.; Higgins, M. J.

    2016-02-01

    Conductive colloidal probe Atomic Force-Scanning Electrochemical Microscopy (AFM-SECM) is a new approach, which employs electrically insulated AFM probes except for a gold-coated colloid located at the end of the cantilever. Hence, force measurements can be performed while biasing the conductive colloid under physiological conditions. Moreover, such colloids can be modified by electrochemical polymerization resulting, e.g. in conductive polymer-coated spheres, which in addition may be loaded with specific dopants. In contrast to other AFM-based single cell force spectroscopy measurements, these probes allow adhesion measurements at the cell-biomaterial interface on multiple cells in a rapid manner while the properties of the polymer can be changed by applying a bias. In addition, spatially resolved electrochemical information e.g., oxygen reduction can be obtained simultaneously. Conductive colloid AFM-SECM probes modified with poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) are used for single cell force measurements in mouse fibroblasts and single cell interactions are investigated as a function of the applied potential.Conductive colloidal probe Atomic Force-Scanning Electrochemical Microscopy (AFM-SECM) is a new approach, which employs electrically insulated AFM probes except for a gold-coated colloid located at the end of the cantilever. Hence, force measurements can be performed while biasing the conductive colloid under physiological conditions. Moreover, such colloids can be modified by electrochemical polymerization resulting, e.g. in conductive polymer-coated spheres, which in addition may be loaded with specific dopants. In contrast to other AFM-based single cell force spectroscopy measurements, these probes allow adhesion measurements at the cell-biomaterial interface on multiple cells in a rapid manner while the properties of the polymer can be changed by applying a bias. In addition, spatially resolved electrochemical

  4. AFM and XPA data on structural features and properties of films and powders based on naphthalocyanines

    NASA Astrophysics Data System (ADS)

    Ramonova, A. G.; Nakusov, A. T.; Sozanov, V. G.; Bliev, A. P.; Magkoev, T. T.

    2015-06-01

    The template synthesis is used to produce powders and films based on naphthalocyanines and the corresponding metal complexes (Pc, CuPc, and NiPc). The atomic-force microscopy (AFM) and X-ray phase analysis (XPA) are employed in the study of structure and phase of fine powders and nanostructured films. The AFM data are used to determine the orientation and density of primary particles packed in the film. The XPA method is used to study the chemical composition and crystal structure of the synthesized samples. The regularities related to the structural features that affect the electrophysical properties of the films under study are revealed.

  5. Presence and sources of anthropogenic perfluoroalkyl acids in high-consumption tap-water based beverages.

    PubMed

    Eschauzier, Christian; Hoppe, Maria; Schlummer, Martin; de Voogt, Pim

    2013-01-01

    This study investigates the presence and sources of perfluorinated alkyl acids (PFAAs) in tap water and corresponding tap-water based beverages such as coffee and cola collected in the city of Amsterdam, The Netherlands. Exposure pathways studies have shown that low concentrations of PFAA in tap water already may pose a high contribution to daily human exposure. Tap water samples (n=4) had higher concentrations of PFAAs than the corresponding post-mixed cola (n=4). The lower PFAA levels in the cola were attributed to the pre-treatment of tap water in the mixing machines and dilution with cola syrup. In coffee samples from a coffee machine perfluorooctanoic acid (PFOA) at 4 ng L(-1) was the dominating analyte (n=12). The concentrations of PFHpA, PFOA and non branched PFOS were found to be significantly higher in manually (self) brewed coffee than in the corresponding tap water (n=4). The contribution from short-chain PFAA analogs could not be quantified due to low recoveries. Leaching experiments at different temperatures were performed with fluoropolymers-containing tubes to investigate the potential of leaching from tubes used in beverage preparation (n=16). Fluoropolymer tubes showed leaching of PFAAs at high (80°C) temperature but its relevance for contamination of beverages in practice is small. The specific contribution from perfluoropolymer tubing inside the beverage preparation machines could not be assessed since no information was available from the manufacturers. The present study shows that although different beverage preparation processes possibly affect the concentrations of PFAAs encountered in the final consumed product, the water used for preparation remains the most important source of PFAAs. This in turn has implications for areas where drinking water is contaminated. Tap-water based beverages will possibly be an additional source of human exposure to PFAAs and need to be considered in exposure modeling. PMID:22939265

  6. Stable isotope ratios of tap water in the contiguous United States

    NASA Astrophysics Data System (ADS)

    Bowen, Gabriel J.; Ehleringer, James R.; Chesson, Lesley A.; Stange, Erik; Cerling, Thure E.

    2007-03-01

    Understanding links between water consumers and climatological (precipitation) sources is essential for developing strategies to ensure the long-term sustainability of water supplies. In pursing this understanding a need exists for tools to study and monitor complex human-hydrological systems that involve high levels of spatial connectivity and supply problems that are regional, rather than local, in nature. Here we report the first national-level survey of stable isotope ratios in tap water, including spatially and temporally explicit samples from a large number of cities and towns across the contiguous United States. We show that intra-annual ranges of tap water isotope ratios are relatively small (e.g., <10‰ for δ2H) at most sites. In contrast, spatial variation in tap water isotope ratios is very large, spanning ranges of 163‰ for δ2H and 23.6‰ for δ18O. The spatial distribution of tap water isotope ratios at the national level is similar to that of stable isotope ratios of precipitation. At the regional level, however, pervasive differences between tap water and precipitation isotope ratios can be attributed to hydrological factors in the water source to consumer chain. These patterns highlight the potential for monitoring of tap water isotope ratios to contribute to the study of regional water supply stability and provide warning signals for impending water resource changes. We present the first published maps of predicted tap water isotope ratios for the contiguous United States, which will be useful in guiding future research on human-hydrological systems and as a tool for applied forensics and traceability studies.

  7. Thermodynamics of peptide binding to the transporter associated with antigen processing (TAP).

    PubMed

    Neumann, Lars; Abele, Rupert; Tampé, Robert

    2002-12-13

    The ATP-binding cassette (ABC) transporter TAP plays an essential role in antigen processing and immune response to infected or malignant cells. TAP translocates proteasomal degradation products from the cytosol into the endoplasmic reticulum, where MHC class I molecules are loaded with these peptides. Kinetically stable peptide-MHC complexes are transported to the cell surface for inspection by cytotoxic T lymphocytes. The transport cycle of TAP is initiated by peptide binding, which is responsible for peptide selection and for stimulation of ATP-hydrolysis and subsequent translocation. Here we have analysed the driving forces for the formation of the peptide-TAP complex by kinetic and thermodynamic methods. First, the apparent peptide association and dissociation rates were determined at various temperatures. Strikingly, very high activation energies for apparent association (E(a)(ass)=106 kJmol(-1)) and dissociation (E(a)(diss)=80 kJmol(-1)) of the peptide-TAP complex were found. Next, the temperature-dependence of the peptide affinity constants was investigated by equilibrium-binding assays. Along with calculations of free enthalpy deltaG, enthalpy deltaH and entropy deltaS, a large positive change in heat capacity was resolved (deltaC degrees =23 kJmol(-1)K(-1)), indicating a fundamental structural reorganization of the TAP complex upon peptide binding. The inspection of the conformational entropy reveals that approximately one-fourth of all TAP residues is rearranged. These thermodynamic studies indicate that at physiological temperature, peptide binding is endothermic and driven by entropy. PMID:12470952

  8. Cross-cultural influences on rhythm processing: reproduction, discrimination, and beat tapping

    PubMed Central

    Cameron, Daniel J.; Bentley, Jocelyn; Grahn, Jessica A.

    2015-01-01

    The structures of musical rhythm differ between cultures, despite the fact that the ability to entrain movement to musical rhythm occurs in virtually all individuals across cultures. To measure the influence of culture on rhythm processing, we tested East African and North American adults on perception, production, and beat tapping for rhythms derived from East African and Western music. To assess rhythm perception, participants identified whether pairs of rhythms were the same or different. To assess rhythm production, participants reproduced rhythms after hearing them. To assess beat tapping, participants tapped the beat along with repeated rhythms. We expected that performance in all three tasks would be influenced by the culture of the participant and the culture of the rhythm. Specifically, we predicted that a participant’s ability to discriminate, reproduce, and accurately tap the beat would be better for rhythms from their own culture than for rhythms from another culture. In the rhythm discrimination task, there were no differences in discriminating culturally familiar and unfamiliar rhythms. In the rhythm reproduction task, both groups reproduced East African rhythms more accurately than Western rhythms, but East African participants also showed an effect of cultural familiarity, leading to a significant interaction. In the beat tapping task, participants in both groups tapped the beat more accurately for culturally familiar than for unfamiliar rhythms. Moreover, there were differences between the two participant groups, and between the two types of rhythms, in the metrical level selected for beat tapping. The results demonstrate that culture does influence the processing of musical rhythm. In terms of the function of musical rhythm, our results are consistent with theories that musical rhythm enables synchronization. Musical rhythm may foster musical cultural identity by enabling within-group synchronization to music, perhaps supporting social cohesion

  9. Assessment of water use for estimating exposure to tap water contaminants.

    PubMed

    Shimokura, G H; Savitz, D A; Symanski, E

    1998-02-01

    Epidemiological studies examining the association between exposure to tap water contaminants (such as chlorination by-products) and disease outcomes (such as cancer and adverse reproductive outcomes) have been limited by inaccurate exposure assessment. Failure to take into account the variation in beverage and tap water consumption and exposure to volatile contaminants through inhalation and dermal absorption can introduce misclassification in assessing the association between exposure to tap water contaminants and health. To refine exposure assessment of tap water contaminants, we describe in detail the tap water consumption, showering, and bathing habits of pregnant women and their male partners as assessed by a questionnaire and a 3-day water diary. We found good agreement between questionnaire and 3-day water diary values for drinking water intake (Pearson's r = 0.78) and for time spent showering(r = 0.68) and bathing (r = 0.78). Half of the participants consumed tap water on a regular basis with an overall mean +/- 1 standard deviation (SD) of 0. 78 +/- 0.51 l/day. Our results further suggest that full-time employees, compared to women working part-time or less, have more heterogeneous consumption patterns over time. Seventy-nine percent of women and 94% of men took showers for an average of 11.6 +/-4.0 min and 10.4 +/- 4.8 min, respectively. Baths were taken more frequently by women than men (21% vs. 3%) for an average of 22.9 +/-10.1 min and 21.3 +/- 12.4 min, respectively. Thus, these patterns of tap water use should be considered in the design and interpretation of environmental epidemiology studies. PMID:9432970

  10. An Evaluation of the Impacts of AF-M315E Propulsion Systems for Varied Mission Applications

    NASA Technical Reports Server (NTRS)

    Deans, Matthew C.; Oleson, Steven R.; Fittje, James; Colozza, Anthony; Packard, Tom; Gyekenyesi, John; McLean, Christopher H.; Spores, Ronald A.

    2015-01-01

    The purpose of the AF-M315E COMPASS study is to identify near-term (3-5 years) and long term (5 years +) opportunities for infusion, specifically the thruster and associated component technologies being developed as part of the GPIM project. Develop design reference missions which show the advantages of the AF-M315E green propulsion system. Utilize a combination of past COMPASS designs and selected new designs to demonstrate AF-M315E advantages. Use the COMPASS process to show the puts and takes of using AF-M315E at the integrated system level.

  11. Novel combination of near-field s-SNOM microscopy with peak-force tapping for nano-chemical and nano-mechanical material characterization with sub-20 nm spatial resolution

    NASA Astrophysics Data System (ADS)

    Wagner, Martin; Carneiro, Karina; Habelitz, Stefan; Mueller, Thomas; BNS Team; UCSF Team

    Heterogeneity in material systems requires methods for nanoscale chemical identification. Scattering scanning near-field microscopy (s-SNOM) is chemically sensitive in the infrared fingerprint region while providing down to 10 nm spatial resolution. This technique detects material specific tip-scattering in an atomic force microscope. Here, we present the first combination of s-SNOM with peak-force tapping (PFT), a valuable AFM technique that allows precise force control between tip and sample down to 10s of pN. The latter is essential for imaging fragile samples, but allows also quantitative extraction of nano-mechanical properties, e.g. the modulus. PFT can further be complemented by KPFM or conductive AFM for nano-electrical mapping, allowing access to nanoscale optical, mechanical and electrical information in a single instrument. We will address several questions ranging from graphene plasmonics to material distributions in polymers. We highlight a biological application where dental amelogenin protein was studied via s-SNOM to learn about its self-assembly into nanoribbons. At the same time PFT allows to track crystallization to distinguish protein from apatite crystals for which amelogenin is supposed to act as a template.

  12. Demographic factors associated with perceptions about water safety and tap water consumption among adults in Santa Clara County, California, 2011.

    PubMed

    van Erp, Brianna; Webber, Whitney L; Stoddard, Pamela; Shah, Roshni; Martin, Lori; Broderick, Bonnie; Induni, Marta

    2014-01-01

    The objective of this study was to examine differences in tap water consumption and perceptions of bottle versus tap water safety for Hispanics and non-Hispanic whites, as well as associations with other demographic characteristics. Data are from the Santa Clara County, California, Dietary Practices Survey (2011; N = 306). We used logistic regression to examine associations between demographic characteristics and 1) perceptions that bottled water is safer than tap and 2) primarily consuming tap water. Hispanics were less likely than non-Hispanic whites to primarily drink tap water (OR = 0.33; 95% CI, 0.11-0.99), although there was no significant difference in perceptions that bottled water is safer between these groups (OR = 0.50; 95% CI, 0.11-2.27). Hispanics may be an important population for interventions promoting tap water consumption. PMID:24921901

  13. Unexpected lack of specificity of a rabbit polyclonal TAP-L (ABCB9) antibody

    PubMed Central

    van Endert, Peter; Lawand, Myriam

    2015-01-01

    In this article, we describe the surprising non-specific reactivity in immunoblots of a rabbit polyclonal antibody (ref. Abcam 86222) expected to recognize the transporter associated with antigen processing like (TAP-L, ABCB9) protein. Although this antibody, according to company documentation, recognizes a band with the expected molecular weight of 84 kDa in HeLa, 293T and mouse NIH3T3 whole-cell lysates, we found that this band is also present in immunoblots of TAP-L deficient bone marrow-derived dendritic cell (BMDC) whole-cell lysates in three independent replicates. We performed extensive verification by multiple PCR tests to confirm the complete absence of the ABCB9 gene in our TAP-L deficient mice. We conclude that the antibody tested cross-reacts with an unidentified protein present in TAP-L knockout cells, which coincidentally runs at the same molecular weight as TAP-L. These findings underline the pitfalls of antibody specificity testing in the absence of cells lacking expression of the target protein.

  14. TAp73 is essential for germ cell adhesion and maturation in testis

    PubMed Central

    Holembowski, Lena; Kramer, Daniela; Riedel, Dietmar; Sordella, Raffaella; Nemajerova, Alice; Dobbelstein, Matthias

    2014-01-01

    A core evolutionary function of the p53 family is to protect the genomic integrity of gametes. However, the role of p73 in the male germ line is unknown. Here, we reveal that TAp73 unexpectedly functions as an adhesion and maturation factor of the seminiferous epithelium orchestrating spermiogenesis. TAp73 knockout (TAp73KO) and p73KO mice, but not ΔNp73KO mice, display a “near-empty seminiferous tubule” phenotype due to massive premature loss of immature germ cells. The cellular basis of this phenotype is defective cell–cell adhesions of developing germ cells to Sertoli nurse cells, with likely secondary degeneration of Sertoli cells, including the blood–testis barrier, which leads to disruption of the adhesive integrity and maturation of the germ epithelium. At the molecular level, TAp73, which is produced in germ cells, controls a coordinated transcriptional program of adhesion- and migration-related proteins including peptidase inhibitors, proteases, receptors, and integrins required for germ–Sertoli cell adhesion and dynamic junctional restructuring. Thus, we propose the testis as a unique organ with strict division of labor among all family members: p63 and p53 safeguard germ line fidelity, whereas TAp73 ensures fertility by enabling sperm maturation. PMID:24662569

  15. TAp73 suppresses tumor angiogenesis through repression of proangiogenic cytokines and HIF-1α activity

    PubMed Central

    Stantic, Marina; Sakil, Habib A. M.; Zirath, Hanna; Fang, Trixy; Sanz, Gema; Fernandez-Woodbridge, Alejandro; Marin, Ana; Susanto, Evelyn; Mak, Tak W.; Arsenian Henriksson, Marie; Wilhelm, Margareta T.

    2015-01-01

    The p53-family member TAp73 is known to function as a tumor suppressor and regulates genomic integrity, cellular proliferation, and apoptosis; however, its role in tumor angiogenesis is poorly understood. Here we demonstrate that TAp73 regulates tumor angiogenesis through repression of proangiogenic and proinflammatory cytokines. Importantly, loss of TAp73 results in highly vascularized tumors, as well as an increase in vessel permeability resulting from disruption of vascular endothelial-cadherin junctions between endothelial cells. In contrast, loss of the oncogenic p73 isoform ΔNp73 leads to reduced blood vessel formation in tumors. Furthermore, we show that up-regulated ΔNp73 levels are associated with increased angiogenesis in human breast cancer and that inhibition of TAp73 results in an accumulation of HIF-1α and up-regulation of HIF-1α target genes. Taken together, our data demonstrate that loss of TAp73 or ΔNp73 up-regulation activates the angiogenic switch that stimulates tumor growth and progression. PMID:25535357

  16. TAp73 is required for spermatogenesis and the maintenance of male fertility

    PubMed Central

    Inoue, Satoshi; Tomasini, Richard; Rufini, Alessandro; Elia, Andrew J.; Agostini, Massimiliano; Amelio, Ivano; Cescon, Dave; Dinsdale, David; Zhou, Lily; Harris, Isaac S.; Lac, Sophie; Silvester, Jennifer; Li, Wanda Y.; Sasaki, Masato; Haight, Jillian; Brüstle, Anne; Wakeham, Andrew; Mckerlie, Colin; Jurisicova, Andrea; Melino, Gerry; Mak, Tak W.

    2014-01-01

    The generation of viable sperm proceeds through a series of coordinated steps, including germ cell self-renewal, meiotic recombination, and terminal differentiation into functional spermatozoa. The p53 family of transcription factors, including p53, p63, and p73, are critical for many physiological processes, including female fertility, but little is known about their functions in spermatogenesis. Here, we report that deficiency of the TAp73 isoform, but not p53 or ΔNp73, results in male infertility because of severe impairment of spermatogenesis. Mice lacking TAp73 exhibited increased DNA damage and cell death in spermatogonia, disorganized apical ectoplasmic specialization, malformed spermatids, and marked hyperspermia. We demonstrated that TAp73 regulates the mRNA levels of crucial genes involved in germ stem/progenitor cells (CDKN2B), spermatid maturation/spermiogenesis (metalloproteinase and serine proteinase inhibitors), and steroidogenesis (CYP21A2 and progesterone receptor). These alterations of testicular histology and gene expression patterns were specific to TAp73 null mice and not features of mice lacking p53. Our work provides previously unidentified in vivo evidence that TAp73 has a unique role in spermatogenesis that ensures the maintenance of mitotic cells and normal spermiogenesis. These results may have implications for the diagnosis and management of human male infertility. PMID:24449892

  17. Continuation tapping to triggered melodies: motor resonance effects of melodic motion.

    PubMed

    Ammirante, Paolo; Thompson, William F

    2012-01-01

    Common Coding theory predicts that perceived action should resonate in produced action to which it bears some resemblance. Here we show that the qualities of motion commonly attributed to melodies are instantiated in motor plans that control timed movements. Participants attempted to tap a steady beat. Each tap triggered a sounded tone, and successive tones were systematically varied in pitch to form short melodies. Tapping behavior was monitored with motion capture. Although instructed to ignore them, triggered tones systematically affected timing and finger movement. When slower melodic motion was implied by a contour change or a smaller pitch displacement, the interval-tap interval (ITI) was longer. When faster melodic motion was implied by a preserved pitch contour or a larger pitch displacement, ITI was shorter. Kinematic recordings suggested that ITI Error arose from an initial failure to disambiguate perception (i.e., velocity implied by melodic motion) from action (i.e., finger velocity [FV]). Early in the tap trajectory, slower FV was associated with longer ITI and faster FV was associated with shorter ITI. These associations were reversed near mid-trajectory, suggesting a transition from execution of motor planning to online control (Glover et al. in Exp Brain Res 154:103-108, 2004). PMID:22038717

  18. Comparison of timing and force control of foot tapping between elderly and young subjects

    PubMed Central

    Takimoto, Koji; Takebayashi, Hideaki; Miyamoto, Kenzo; Takuma, Yutaka; Inoue, Yoshikazu; Miyamoto, Shoko; Okabe, Takao; Okuda, Takahiro; Kaba, Hideto

    2016-01-01

    [Purpose] To examine the ability of young and elderly individuals to control the timing and force of periodic sequential foot tapping. [Subjects and Methods] Participants were 10 young (age, 22.1 ± 4.3 years) and 10 elderly individuals (74.8 ± 6.7 years) who were healthy and active. The foot tapping task consisted of practice (stimulus-synchronized tapping with visual feedback) and recall trials (self-paced tapping without visual feedback), periodically performed in this order, at 500-, 1,000-, and 2,000-ms target interstimulus-onset intervals, with a target force of 20% maximum voluntary contraction of the ankle plantar-flexor muscle. [Results] The coefficients of variation of force and intertap interval, used for quantifying the steadiness of the trials, were significantly greater in the elderly than in the young individuals. At the 500-ms interstimulus-onset interval, age-related effects were observed on the normalized mean absolute error of force, which was used to quantify the accuracy of the trials. The coefficients of variation of intertap interval for elderly individuals were significantly greater in the practice than in the recall trials at the 500- and 1,000-ms interstimulus-onset intervals. [Conclusion] The elderly individuals exhibited greater force and timing variability than the young individuals and showed impaired visuomotor processing during foot tapping sequences. PMID:27390445

  19. Selective enhancement of individual cantilever high resonance modes.

    PubMed

    Penedo, Marcos; Hormeño, Silvia; Prieto, Patricia; Alvaro, Raquel; Anguita, José; Briones, Fernando; Luna, Mónica

    2015-12-01

    Multifrequency atomic force microscopy (AFM) in liquid media where several eigenmodes or harmonics are simultaneously excited is improving the performance of the scanning probe techniques in biological studies. As a consequence, an important effort is being made to search for a reliable, efficient and strong cantilever high mode excitation method that operates in liquids. In this work we present (theoretical and experimentally) a technique for improving the efficiency of the most common excitation methods currently used in AFM operated in liquids: photothermal, torque (MAC Mode™) and magnetostriction. By etching specific areas of the cantilever coating, the oscillation amplitude (both flexural and torsional) of each specific eigenmode increases, leading to an improvement in signal to noise ratio of the multifrequency techniques. As an alternative, increment in high mode oscillation amplitude is also obtained by Ga(+) ion implantation in the specific areas of the magnetic material. PMID:26559931

  20. Selective enhancement of individual cantilever high resonance modes

    NASA Astrophysics Data System (ADS)

    Penedo, Marcos; Hormeño, Silvia; Prieto, Patricia; Alvaro, Raquel; Anguita, José; Briones, Fernando; Luna, Mónica

    2015-12-01

    Multifrequency atomic force microscopy (AFM) in liquid media where several eigenmodes or harmonics are simultaneously excited is improving the performance of the scanning probe techniques in biological studies. As a consequence, an important effort is being made to search for a reliable, efficient and strong cantilever high mode excitation method that operates in liquids. In this work we present (theoretical and experimentally) a technique for improving the efficiency of the most common excitation methods currently used in AFM operated in liquids: photothermal, torque (MAC Mode™) and magnetostriction. By etching specific areas of the cantilever coating, the oscillation amplitude (both flexural and torsional) of each specific eigenmode increases, leading to an improvement in signal to noise ratio of the multifrequency techniques. As an alternative, increment in high mode oscillation amplitude is also obtained by Ga+ ion implantation in the specific areas of the magnetic material.