WorldWideScience

Sample records for single mechanism acting

  1. Single Audit: Single Audit Act Effectiveness Issues

    National Research Council Canada - National Science Library

    Thompson, Sally

    2002-01-01

    As discussed in the report we are releasing today, our work to review agency actions to ensure that recipients take timely and appropriate corrective actions to fix audit findings contained in single...

  2. Comparison of double-acting and single-acting synthetic jets

    Czech Academy of Sciences Publication Activity Database

    Hsu, S.S.; Trávníček, Zdeněk; Chou, C.-C.; Chen, C. C.; Wang, A. B.

    2013-01-01

    Roč. 203, December (2013), s. 291-299 ISSN 0924-4247 Institutional support: RVO:61388998 Keywords : synthetic jet * double-acting & single acting machines * PIV Subject RIV: BK - Fluid Dynamics Impact factor: 1.943, year: 2013 http://dx.doi.org/10.1016/j.sna.2013.09.005

  3. Single banking supervision and the single supervisory mechanism

    Directory of Open Access Journals (Sweden)

    Gheorghe, C. A.

    2013-06-01

    Full Text Available A resolution seems to have been found for the banking crisis. The first steps have been made towards the construction of the Economic and Monetary Union, steps involving the single supervision of banks, in order to avoid the discount of a new financial crisis on the expense of the EU state members. The Single Supervisory Mechanism – SSM is to become effective as of March 1, 2014, at the earliest.

  4. Continuum mechanics of single-substance bodies

    CERN Document Server

    Eringen, A Cemal

    1975-01-01

    Continuum Physics, Volume II: Continuum Mechanics of Single-Substance Bodies discusses the continuum mechanics of bodies constituted by a single substance, providing a thorough and precise presentation of exact theories that have evolved during the past years. This book consists of three parts-basic principles, constitutive equations for simple materials, and methods of solution. Part I of this publication is devoted to a discussion of basic principles irrespective of material geometry and constitution that are valid for all kinds of substances, including composites. The geometrical notions, k

  5. Mechanical Properties Of Single Crystal Ceramics

    Science.gov (United States)

    Rowcliffe, D. J.; Johnson, S. M.

    1987-03-01

    Approaches to characterizing the mechanical behavior of single crystal ceramics are reviewed. Consideration is given to techniques applicable to large crystals and to indentation techniques that can be used on crystals of 1 mm or less. The importance of flaws in controlling the mechanical behavior of brittle ceramics is discussed, leading to an emphasis on fracture mechanics methods. These techniques are applicable to the determination of fracture toughness and to the measurement of slow crack growth in aggresive environments. Indentation processes have been analyzed extensively and the good understanding of stress fields and micro-mechanics of indentation has led to techniques to measure hardness, toughness and elastic modulus. Measurements of hardness anistropy can be used to determine slip planes and also provide considerable information on local plastic flow in brittle crystals.

  6. Mechanism of single atom switch on silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Thirstrup, C.

    1998-01-01

    We demonstrate single atom switch on silicon which operates by displacement of a hydrogen atom on the silicon (100) surface at room temperature. We find two principal effects by which the switch is controlled: a pronounced maximum of the switching probability as function of sample bias...... and a preferred direction of switching as function of STM tip position. Based on first principles calculations, are show that this behaviour is due to a novel mechanism involving an electronic excitation of a localized surface resonance. (C) 1998 Elsevier Science B.V. All rights reserved....

  7. Single-ion nonlinear mechanical oscillator

    International Nuclear Information System (INIS)

    Akerman, N.; Kotler, S.; Glickman, Y.; Dallal, Y.; Keselman, A.; Ozeri, R.

    2010-01-01

    We study the steady-state motion of a single trapped ion oscillator driven to the nonlinear regime. Damping is achieved via Doppler laser cooling. The ion motion is found to be well described by the Duffing oscillator model with an additional nonlinear damping term. We demonstrate here the unique ability of tuning both the linear as well as the nonlinear damping coefficients by controlling the laser-cooling parameters. Our observations pave the way for the investigation of nonlinear dynamics on the quantum-to-classical interface as well as mechanical noise squeezing in laser-cooling dynamics.

  8. Investigation of Chirality Selection Mechanism of Single Walled Carbon Nanotube

    Science.gov (United States)

    2016-12-13

    AFRL-AFOSR-JP-TR-2017-0007 Investigation of Chirality Selection Mechanism of Single -Walled Carbon Nanotube Seun Min Kim KOREA INSTITUTE OF SCIENCE...Selection Mechanism of Single -Walled Carbon Nanotube 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1-4099 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR...research involved investigation of two fundamental mechanisms of carbon nanotube (CNT) growth: chirality selection of single -walled CNT (SWCNT) and

  9. Optimal mechanisms for single machine scheduling

    NARCIS (Netherlands)

    Heydenreich, B.; Mishra, D.; Müller, R.; Uetz, Marc Jochen; Papadimitriou, C.; Zhang, S.

    2008-01-01

    We study the design of optimal mechanisms in a setting here job-agents compete for being processed by a service provider that can handle one job at a time. Each job has a processing time and incurs a waiting cost. Jobs need to be compensated for waiting. We consider two models, one where only the

  10. Molecular mechanics applied to single-walled carbon nanotubes

    OpenAIRE

    Ávila,Antonio Ferreira; Lacerda,Guilherme Silveira Rachid

    2008-01-01

    Single-walled carbon nanotubes, with stiffness of 1.0 TPa and strength of 60 GPa, are a natural choice for high strength materials. A problem, however, arises when experimental data are compiled. The large variability of experimental data leads to the development of numerical models denominated molecular mechanics, which is a "symbiotic" association of molecular dynamics and solid mechanics. This paper deals with molecular mechanics simulations of single-walled carbon nanotubes. To be able to...

  11. Adderall XR: long acting stimulant for single daily dosing.

    Science.gov (United States)

    Sallee, Floyd R; Smirnoff, Alexander V

    2004-11-01

    Adderall XR (SLI381) is the latest addition to the group of psychostimulant formulations, which provides the mixed amphetamine salts contained in Adderall as a single-daily dose formulation. Adderall XR is indicated for the treatment of attention deficit hyperactivity disorder in children and adolescents, with recent US Food and Drug Administration approval for attention deficit hyperactivity disorder in adults. Novel and important aspects of Adderall XR is its 12 h duration of action, relative superior efficacy to nonstimulant atomoxetine in a comparator trial, and significant quality of life impact in children, confirmed by the largest effectiveness trial yet to be performed for any attention deficit hyperactivity disorder therapy. Potentially important benefits of Adderall XR are proven safety and efficacy in adults with attention deficit hyperactivity disorder and positive postmarketing findings in treating oppositional defiant disorder -- the most common comorbidity in children with attention deficit hyperactivity disorder. This review summarizes the important properties of Adderall XR, to include a distinct two-stage delivery system and combination of active ingredients, offering unique advantages. Relevant clinical trials and the newest data from meeting reports are also discussed.

  12. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    - rent work to evaluate the mechanical properties of Zigzag, Armchair and Chiral Single wall Carbon Nanotubes (SWCNT) of different diameters and chiralities. Three dif- ferent types of atomic bonds, that is Carbon–Carbon covalent bond and ...

  13. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    40, Part 4, June 2015, pp. 1301–1311. c Indian Academy of Sciences. Estimation of mechanical properties of single wall carbon nanotubes using molecular mechanics approach. P SUBBA RAO1,2,∗, SUNIL ANANDATHEERTHA3,. G NARAYANA NAIK1 and S GOPALAKRISHNAN1. 1Department of Aerospace Engineering ...

  14. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    Molecular mechanics based finite element analysis is adopted in the current work to evaluate the mechanical properties of Zigzag, Armchair and Chiral Single wall Carbon Nanotubes (SWCNT) of different diameters and chiralities. Three different types of atomic bonds, that is Carbon–Carbon covalent bond and two types of ...

  15. The bacterial fimbrial tip acts as a mechanical force sensor.

    Directory of Open Access Journals (Sweden)

    Pavel Aprikian

    2011-05-01

    Full Text Available There is increasing evidence that the catch bond mechanism, where binding becomes stronger under tensile force, is a common property among non-covalent interactions between biological molecules that are exposed to mechanical force in vivo. Here, by using the multi-protein tip complex of the mannose-binding type 1 fimbriae of Escherichia coli, we show how the entire quaternary structure of the adhesive organella is adapted to facilitate binding under mechanically dynamic conditions induced by flow. The fimbrial tip mediates shear-dependent adhesion of bacteria to uroepithelial cells and demonstrates force-enhanced interaction with mannose in single molecule force spectroscopy experiments. The mannose-binding, lectin domain of the apex-positioned adhesive protein FimH is docked to the anchoring pilin domain in a distinct hooked manner. The hooked conformation is highly stable in molecular dynamics simulations under no force conditions but permits an easy separation of the domains upon application of an external tensile force, allowing the lectin domain to switch from a low- to a high-affinity state. The conformation between the FimH pilin domain and the following FimG subunit of the tip is open and stable even when tensile force is applied, providing an extended lever arm for the hook unhinging under shear. Finally, the conformation between FimG and FimF subunits is highly flexible even in the absence of tensile force, conferring to the FimH adhesin an exploratory function and high binding rates. The fimbrial tip of type 1 Escherichia coli is optimized to have a dual functionality: flexible exploration and force sensing. Comparison to other structures suggests that this property is common in unrelated bacterial and eukaryotic adhesive complexes that must function in dynamic conditions.

  16. Phonon number measurements using single photon opto-mechanics

    International Nuclear Information System (INIS)

    Basiri-Esfahani, S; Akram, U; Milburn, G J

    2012-01-01

    We describe a system composed of two coupled optical cavity modes with a coupling modulated by a bulk mechanical resonator. In addition, one of the cavity modes is irreversibly coupled to a single photon source. Our scheme is an opto-mechanical realization of the Jaynes–Cummings model where the qubit is a dual rail optical qubit while the bosonic degree of freedom is a matter degree of freedom realized as the bulk mechanical excitation. We show the possibility of engineering phonon number states of the mechanical oscillator in such a system by computing the conditional state of the mechanics after successive photon counting measurements. (paper)

  17. Quasi free mechanism in single photon double ionization of helium

    Energy Technology Data Exchange (ETDEWEB)

    Schoeffler, Markus; Stuck, Christian [Frankfurt Univ., Frankfurt am Main (Germany). Inst. fuer Kernphysik; Lawrence Berkeley National Lab, Berkeley, CA (United States); Jahnke, Till; Waitz, Markus; Trinter, Florian; Lenz, Ute; Schmidt-Boecking, Horst; Doerner, Reinhard [Frankfurt Univ., Frankfurt am Main (Germany). Inst. fuer Kernphysik; Jones, Mathew; Landers, Allen [Auburn University, Auburn, AL (United States); Belkacem, Ali; Weber, Thorsten [Lawrence Berkeley National Lab, Berkeley, CA (United States); Cocke, Lew [Kansas State University, Manhattan, KS (United States)

    2012-07-01

    Double ionization of Helium by a single photon is widely believed to proceed through two mechanisms: knock-off (TS1) or shake-off, with the last one dominating at high photon energies. A new mechanism, termed ''Quasi Free Mechanism'' (QFM) was predicted 35 years ago by Amusia and coworkers, but escaped experimental observation till today. Here we provide the first proof of this mechanism using 800 eV photons from the Advanced Light Source. Fragments (electrons and ions) were measured in coincidence using momentum spectroscopy (COLTRIMS). He{sup (}2+) ions with zero momentum were found - the fingerprint for the QFM.

  18. Single molecule insights on conformational selection and induced fit mechanism

    DEFF Research Database (Denmark)

    Hatzakis, Nikos

    2014-01-01

    of unsynchronized molecules, often masking intrinsic dynamic behavior of proteins and biologically significant transient intermediates. Single molecule measurements are emerging as a powerful tool for characterizing protein function. They offer the direct observation and quantification of the activity, abundance...... and lifetime of multiple states and transient intermediates in the energy landscape, that are typically averaged out in non-synchronized ensemble measurements. Here we survey new insights from single molecule studies that advance our understanding of the molecular mechanisms underlying biomolecular recognition....

  19. DeActs : genetically encoded tools for perturbing the actin cytoskeleton in single cells

    NARCIS (Netherlands)

    Harterink, Martin; Santos Esteves da Silva, Marta; Will, Lena; Turan, Julia; Ibrahim, Adiljan; Lang, Alexander E; Van Battum, Eljo Y; Pasterkamp, R Jeroen; Kapitein, Lukas C; Kudryashov, Dmitri; Barres, Ben A; Hoogenraad, Casper C; Zuchero, J Bradley

    2017-01-01

    The actin cytoskeleton is essential for many fundamental biological processes, but tools for directly manipulating actin dynamics are limited to cell-permeable drugs that preclude single-cell perturbations. Here we describe DeActs, genetically encoded actin-modifying polypeptides, which effectively

  20. Electrical and mechanical effects in single-molecule junctions

    NARCIS (Netherlands)

    Seldenthuis, J.S.

    2011-01-01

    In single-molecule junctions, the behavior of a device is determined by the properties of an individual molecule. In this thesis we develop several models to describe both electrical and mechanical effects in such devices, which can be used to design molecules with a specific functionality. We show

  1. Antidepressant effects of ketamine: mechanisms underlying fast-acting novel antidepressants

    Directory of Open Access Journals (Sweden)

    Caroline Ann Browne

    2013-12-01

    Full Text Available Newer antidepressants are needed for the many individuals with major depressive disorder that do not respond adequately to treatment and because of a delay of weeks before the emergence of therapeutic effects. Recent evidence from clinical trials shows that the NMDA antagonist ketamine is a revolutionary novel antidepressant because it acts rapidly and is effective for treatment-resistant patients. A single infusion of ketamine alleviates depressive symptoms in treatment-resistant depressed patients within hours and these effects may be sustained for up to 2 weeks. Although the discovery of ketamine’s effects has reshaped drug discovery for antidepressants, the psychotomimetic properties of this compound limit the use of this therapy to the most severely ill patients. In order to develop additional antidepressants like ketamine, adequate preclinical behavioral screening paradigms for fast-acting antidepressants need to be established and used to identify the underlying neural mechanisms. This review examines the preclinical literature attempting to model the antidepressant-like effects of ketamine. Acute administration of ketamine has produced effects in behavioral screens for antidepressants like the forced swim test, novelty suppression of feeding and in rodent models for depression. Protracted behavioral effects of ketamine have been reported to appear after a single treatment that last for days. This temporal pattern is similar to its clinical effects and may serve as a new animal paradigm for rapid antidepressant effects in humans. In addition, protracted changes in molecules mediating synaptic plasticity have been implicated in mediating the antidepressant-like behavioral effects of ketamine. Current preclinical studies are examining compounds with more specific pharmacological effects at glutamate receptors and synapses in order to develop additional rapidly acting antidepressants without the hallucinogenic side effects or abuse

  2. Enhancing the mechanical properties of single-crystal CVD diamond.

    Science.gov (United States)

    Liang, Qi; Yan, Chih-Shiue; Meng, Yufei; Lai, Joseph; Krasnicki, Szczesny; Mao, Ho-Kwang; Hemley, Russell J

    2009-09-09

    Approaches for enhancing the strength and toughness of single-crystal diamond produced by chemical vapor deposition (CVD) at high growth rates are described. CVD processes used to grow single-crystal diamond in high density plasmas were modified to incorporate boron and nitrogen. Semi-quantitative studies of mechanical properties were carried out using Vickers indentation techniques. The introduction of boron in single-crystal CVD diamond can significantly enhance the fracture toughness of this material without sacrificing its high hardness (∼78 GPa). Growth conditions were varied to investigate its effect on boron incorporation and optical properties by means of photoluminescence, infrared, and ultraviolet-visible absorption spectroscopy. Boron can be readily incorporated into single-crystal diamond by the methods used, but with nitrogen addition, the incorporation of boron was hindered. The spectroscopic measurements indicate that nitrogen and boron coexist in the diamond structure, which helps explain the origin of the enhanced fracture toughness of this material. Further, low pressure/high temperature annealing can enhance the intrinsic hardness of single-crystal CVD diamond by a factor of two without appreciable loss in fracture toughness. This doping and post-growth treatment of diamond may lead to new technological applications that require enhanced mechanical properties of diamond.

  3. Single-cell mechanics: the parallel plates technique.

    Science.gov (United States)

    Bufi, Nathalie; Durand-Smet, Pauline; Asnacios, Atef

    2015-01-01

    We describe here the parallel plates technique which enables quantifying single-cell mechanics, either passive (cell deformability) or active (whole-cell traction forces). Based on the bending of glass microplates of calibrated stiffness, it is easy to implement on any microscope, and benefits from protocols and equipment already used in biology labs (coating of glass slides, pipette pullers, micromanipulators, etc.). We first present the principle of the technique, the design and calibration of the microplates, and various surface coatings corresponding to different cell-substrate interactions. Then we detail the specific cell preparation for the assays, and the different mechanical assays that can be carried out. Finally, we discuss the possible technical simplifications and the specificities of each mechanical protocol, as well as the possibility of extending the use of the parallel plates to investigate the mechanics of cell aggregates or tissues. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Mechanism of the superior mechanical strength of nanometer-sized metal single crystals revealed

    KAUST Repository

    Afify, N. D.

    2013-10-01

    Clear understanding of the superior mechanical strength of nanometer-sized metal single crystals is required to derive advanced mechanical components retaining such superiority. Although high quality studies have been reported on nano-crystalline metals, the superiority of small single crystals has neither been fundamentally explained nor quantified to this date. Here we present a molecular dynamics study of aluminum single crystals in the size range from 4.1 nm to 40.5 nm. We show that the ultimate mechanical strength deteriorates exponentially as the single crystal size increases. The small crystals superiority is explained by their ability to continuously form vacancies and to recover them. © 2013 Published by Elsevier B.V.

  5. Mechanisms for tertiary creep of single crystal superalloy

    Science.gov (United States)

    Staroselsky, Alexander; Cassenti, Brice

    2008-12-01

    During the thermal-mechanical loading of high temperature single crystal turbine components, all three creep—stages: primary, secondary and tertiary, manifest themselves and, hence, none of them can be neglected. The development of a creep law that includes all three stages is especially important in the case of non-homogeneous thermal loading of the component where significant stress redistribution and relaxation will result. Thus, local creep analysis is crucial for proper design of damage tolerant airfoils. We have developed a crystallographic-based constitutive model and fully coupled it with damage kinetics. The model extends existing approaches for cyclic and thermal-cyclic loading of anisotropic elasto-viscoplastic deformation behavior and damage kinetics of single-crystal materials, allowing prediction of tertiary creep and failure initiation of high temperature components. Our damage model bridges the gap between dislocation dynamics and the continuum mechanics scales and can be used to represent tertiary as well as primary and secondary creep.

  6. Mechanical properties of hydroxyapatite single crystals from nanoindentation data

    Science.gov (United States)

    Zamiri, A.; De, S.

    2011-01-01

    In this paper we compute elasto-plastic properties of hydroxyapatite single crystals from nanindentation data using a two-step algorithm. In the first step the yield stress is obtained using hardness and Young’s modulus data, followed by the computation of the flow parameters. The computational approach is first validated with data from existing literature. It is observed that hydroxyapatite single crystals exhibit anisotropic mechanical response with a lower yield stress along the [1010] crystallographic direction compared to the [0001] direction. Both work hardening rate and work hardening exponent are found to be higher for indentation along the [0001] crystallographic direction. The stress-strain curves extracted here could be used for developing constitutive models for hydroxyapatite single crystals. PMID:21262492

  7. Declarative Memory Consolidation: Mechanisms Acting during Human Sleep

    Science.gov (United States)

    Gais, Steffen; Born, Jan

    2004-01-01

    Of late, an increasing number of studies have shown a strong relationship between sleep and memory. Here we summarize a series of our own studies in humans supporting a beneficial influence of slow-wave sleep (SWS) on declarative memory formation, and try to identify some mechanisms that might underlie this influence. Specifically, these…

  8. Deformation mechanisms in nanoscale single crystalline electroplated copper pillars

    Science.gov (United States)

    Jennings, Andrew T.

    Scientific research in nanotechnology has enabled advances in a diverse range of applications, such as: electronics, chemical sensing, and cancer treatment. In order to transition these nanotechnology-driven innovations out of the laboratory and into real-world applications, the resilience and mechanical reliability of nanoscale structures must be well understood in order to preserve functionality under real-world operating environments. Understanding the mechanical properties of nanoscale materials is especially important because several authors have shown that single crystalline metal pillars produced through focused-ion-beam milling have unique properties when the pillar diameter, D, approaches nanotechnology-relevant dimensions. The strength, sigma, of these pillars is size-dependent and is well described through a power-law relation showing that smaller is stronger: sigma∝D-n , where n is the exponent and is found to be 0.5≤n≤1.0 in face-centered-cubic metals. In this work, the fundamental deformation mechanisms governing the size-dependent mechanical properties are investigated through uniaxial compression and tension tests of electroplated single crystalline copper pillars with diameters between 75 nm and 1000 nm. At larger pillar diameters, D >125 nm, these copper pillars are shown to obey a similar size-dependent regime, demonstrating that the "smaller is stronger" phenomenon is a function of the pillar microstructure, as opposed to the fabrication route. Furthermore, the dominant dislocation mechanism in this size-dependent regime is shown to be the result of single-arm, or spiral, sources. At smaller pillar diameters, D≤125 nm, a strain-rate-dependent mechanism transition is observed through both the size-strength relation and also quantitative, experimental measures of the activation volume. This new deformation regime is characterized by a size-independent strength and is governed by surface dislocation nucleation, a thermally activated

  9. Transport mechanisms acting in toroidal devices: a theoretician's view

    International Nuclear Information System (INIS)

    Carreras, B.A.

    1992-01-01

    Understanding the basic mechanisms of transport in toroidal confinement devices remains one of the more challenging scientific issues in magnetic confinement. At the same time, it is a critical issue for the magnetic fusion program. Recent progress in understanding fluctuations and transport has been fostered by the development and use of new diagnostics, bringing new perspectives on these studies. This has stimulated new theoretical developments. A view of the most recent issues and progress in this area is given. The role of long wavelengths in core transport and the relation between shear flows and turbulence at the plasma edge are the primary topics considered. (Author)

  10. Mechanical characterization of cellulose single nanofiber by atomic force microscopy

    Science.gov (United States)

    Zhai, Lindong; Kim, Jeong Woong; Lee, Jiyun; Kim, Jaehwan

    2017-04-01

    Cellulose fibers are strong natural fibers and they are renewable, biodegradable and the most abundant biopolymer in the world. So to develop new cellulose fibers based products, the mechanical properties of cellulose nanofibers would be a key. The atomic microscope is used to measure the mechanical properties of cellulose nanofibers based on 3-points bending of cellulose nanofiber. The cellulose nanofibers were generated for an aqueous counter collision system. The cellulose microfibers were nanosized under 200 MPa high pressure. The cellulose nanofiber suspension was diluted with DI water and sprayed on the silicon groove substrate. By performing a nanoscale 3-points bending test using the atomic force microscopy, a known force was applied on the center of the fiber. The elastic modulus of the single nanofiber is obtained by calculating the fiber deflection and several parameters. The elastic modulus values were obtained from different resources of cellulose such as hardwood, softwood and cotton.

  11. Single-molecule mechanics of protein-labelled DNA handles

    Directory of Open Access Journals (Sweden)

    Vivek S. Jadhav

    2016-01-01

    Full Text Available DNA handles are often used as spacers and linkers in single-molecule experiments to isolate and tether RNAs, proteins, enzymes and ribozymes, amongst other biomolecules, between surface-modified beads for nanomechanical investigations. Custom DNA handles with varying lengths and chemical end-modifications are readily and reliably synthesized en masse, enabling force spectroscopic measurements with well-defined and long-lasting mechanical characteristics under physiological conditions over a large range of applied forces. Although these chemically tagged DNA handles are widely used, their further individual modification with protein receptors is less common and would allow for additional flexibility in grabbing biomolecules for mechanical measurements. In-depth information on reliable protocols for the synthesis of these DNA–protein hybrids and on their mechanical characteristics under varying physiological conditions are lacking in literature. Here, optical tweezers are used to investigate different protein-labelled DNA handles in a microfluidic environment under different physiological conditions. Digoxigenin (DIG-dsDNA-biotin handles of varying sizes (1000, 3034 and 4056 bp were conjugated with streptavidin or neutravidin proteins. The DIG-modified ends of these hybrids were bound to surface-modified polystyrene (anti-DIG beads. Using different physiological buffers, optical force measurements showed consistent mechanical characteristics with long dissociation times. These protein-modified DNA hybrids were also interconnected in situ with other tethered biotinylated DNA molecules. Electron-multiplying CCD (EMCCD imaging control experiments revealed that quantum dot–streptavidin conjugates at the end of DNA handles remain freely accessible. The experiments presented here demonstrate that handles produced with our protein–DNA labelling procedure are excellent candidates for grasping single molecules exposing tags suitable for molecular

  12. Mechanism of Positive Allosteric Modulators Acting on AMPA Receptors

    Energy Technology Data Exchange (ETDEWEB)

    Jin,R.; Clark, S.; Weeks, A.; Dudman, J.; Gouaux, E.; Partin, K.

    2005-01-01

    Ligand-gated ion channels involved in the modulation of synaptic strength are the AMPA, kainate, and NMDA glutamate receptors. Small molecules that potentiate AMPA receptor currents relieve cognitive deficits caused by neurodegenerative diseases such as Alzheimer's disease and show promise in the treatment of depression. Previously, there has been limited understanding of the molecular mechanism of action for AMPA receptor potentiators. Here we present cocrystal structures of the glutamate receptor GluR2 S1S2 ligand-binding domain in complex with aniracetam [1-(4-methoxybenzoyl)-2-pyrrolidinone] or CX614 (pyrrolidino-1, 3-oxazino benzo-1, 4-dioxan-10-one), two AMPA receptor potentiators that preferentially slow AMPA receptor deactivation. Both potentiators bind within the dimer interface of the nondesensitized receptor at a common site located on the twofold axis of molecular symmetry. Importantly, the potentiator binding site is adjacent to the 'hinge' in the ligand-binding core 'clamshell' that undergoes conformational rearrangement after glutamate binding. Using rapid solution exchange, patch-clamp electrophysiology experiments, we show that point mutations of residues that interact with potentiators in the cocrystal disrupt potentiator function. We suggest that the potentiators slow deactivation by stabilizing the clamshell in its closed-cleft, glutamate-bound conformation.

  13. Mechanical properties and formation mechanisms of a wire of single gold atoms

    DEFF Research Database (Denmark)

    Rubio-Bollinger, G.; Bahn, Sune Rastad; Agrait, N.

    2001-01-01

    A scanning tunneling microscope supplemented with a force sensor is used to study the mechanical properties of a novel metallic nanostructure: a freely suspended chain of single gold atoms. We find that the bond strength of the nanowire is about twice that of a bulk metallic bond. We perform ab i...... stiffness of the nanostructure is strongly affected by the detailed local atomic arrangement at the chain bases.......A scanning tunneling microscope supplemented with a force sensor is used to study the mechanical properties of a novel metallic nanostructure: a freely suspended chain of single gold atoms. We find that the bond strength of the nanowire is about twice that of a bulk metallic bond. We perform ab...... initio calculations of the force at chain fracture and compare quantitatively with experimental measurements. The observed mechanical failure and nanoelastic processes involved during atomic wire fabrication are investigated using molecular dynamics simulations, and we find that the total effective...

  14. Colloid retention mechanisms in single, saturated, variable-aperture fractures.

    Science.gov (United States)

    Rodrigues, S N; Dickson, S E; Qu, J

    2013-01-01

    The characterization of fractured aquifers is commonly limited to the methodologies developed for unconsolidated porous media aquifers, which results in many uncertainties. Recent work indicates that fractured rocks remove more particulates than they are conventionally credited for. This research was designed to quantify the number of Escherichia coli RS2-GFP retained in single, saturated, variable-aperture fractures extracted from the natural environment. Conservative solute and E. coli RS2-GFP tracer experiments were used to elucidate the relationships between dominant retention mechanisms, aperture field characteristics, and flow rate. A non-destructive method of determining a surrogate measure of a coefficient of variation (COV(S)) for each fracture was used to better understand the transport behaviour of E. coli RS2-GFP. The results from this research all point to the importance of aperture field characterization in understanding the fate and transport of contaminants in fractured aquifers. The mean aperture was a very important characteristic in determining particulate recovery, so were matrix properties, COV(s), and flow rate. It was also determined that attachment is a much more significant retention mechanism than straining under the conditions employed in this research. Finally, it was demonstrated that the dominant retention mechanism in a fracture varies depending on the specific discharge. An improved understanding of the mechanisms that influence the fate and transport of contaminants through fractures will lead to the development of better tools and methodologies for the characterization of fractured aquifers, as well as the ability to manipulate the relevant mechanisms to increase or decrease retention, depending on the application. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Synchronization of impacting mechanical systems with a single constraint

    Science.gov (United States)

    Baumann, Michael; Biemond, J. J. Benjamin; Leine, Remco I.; van de Wouw, Nathan

    2018-01-01

    This paper addresses the synchronization problem of mechanical systems subjected to a single geometric unilateral constraint. The impacts of the individual systems, induced by the unilateral constraint, generally do not coincide even if the solutions are arbitrarily 'close' to each other. The mismatch in the impact time instants demands a careful choice of the distance function to allow for an intuitively correct comparison of the discontinuous solutions resulting from the impacts. We propose a distance function induced by the quotient metric, which is based on an equivalence relation using the impact map. The distance function obtained in this way is continuous in time when evaluated along jumping solutions. The property of maximal monotonicity, which is fulfilled by most commonly used impact laws, is used to significantly reduce the complexity of the distance function. Based on the simplified distance function, a Lyapunov function is constructed to investigate the synchronization problem for two identical one-dimensional mechanical systems. Sufficient conditions for the uncoupled individual systems are provided under which local synchronization is guaranteed. Furthermore, we present an interaction law which ensures global synchronization, also in the presence of grazing trajectories and accumulation points (Zeno behavior). The results are illustrated using numerical examples of a 1-DOF mechanical impact oscillator which serves as stepping stone in the direction of more general systems.

  16. Mechanisms of Cellular Proteostasis: Insights from Single-Molecule Approaches

    Science.gov (United States)

    Bustamante, Carlos J.; Kaiser, Christian M.; Maillard, Rodrigo A.; Goldman, Daniel H.; Wilson, Christian A.M.

    2015-01-01

    Cells employ a variety of strategies to maintain proteome homeostasis. Beginning during protein biogenesis, the translation machinery and a number of molecular chaperones promote correct de novo folding of nascent proteins even before synthesis is complete. Another set of molecular chaperones helps to maintain proteins in their functional, native state. Polypeptides that are no longer needed or pose a threat to the cell, such as misfolded proteins and aggregates, are removed in an efficient and timely fashion by ATP-dependent proteases. In this review, we describe how applications of single-molecule manipulation methods, in particular optical tweezers, are shedding new light on the molecular mechanisms of quality control during the life cycles of proteins. PMID:24895851

  17. Waterbomb base: a symmetric single-vertex bistable origami mechanism

    Science.gov (United States)

    Hanna, Brandon H.; Lund, Jason M.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.

    2014-09-01

    The origami waterbomb base is a single-vertex bistable origami mechanism that has unique properties which may prove useful in a variety of applications. It also shows promise as a test bed for smart materials and actuation because of its straightforward geometry and multiple phases of motion, ranging from simple to more complex. This study develops a quantitative understanding of the symmetric waterbomb base's kinetic behavior. This is done by completing kinematic and potential energy analyses to understand and predict bistable behavior. A physical prototype is constructed and tested to validate the results of the analyses. Finite element and virtual work analyses based on the prototype are used to explore the locations of the stable equilibrium positions and the force-deflection response. The model results are verified through comparisons to measurements on a physical prototype. The resulting models describe waterbomb base behavior and provide an engineering tool for application development.

  18. Waterbomb base: a symmetric single-vertex bistable origami mechanism

    International Nuclear Information System (INIS)

    Hanna, Brandon H; Lund, Jason M; Magleby, Spencer P; Howell, Larry L; Lang, Robert J

    2014-01-01

    The origami waterbomb base is a single-vertex bistable origami mechanism that has unique properties which may prove useful in a variety of applications. It also shows promise as a test bed for smart materials and actuation because of its straightforward geometry and multiple phases of motion, ranging from simple to more complex. This study develops a quantitative understanding of the symmetric waterbomb base's kinetic behavior. This is done by completing kinematic and potential energy analyses to understand and predict bistable behavior. A physical prototype is constructed and tested to validate the results of the analyses. Finite element and virtual work analyses based on the prototype are used to explore the locations of the stable equilibrium positions and the force–deflection response. The model results are verified through comparisons to measurements on a physical prototype. The resulting models describe waterbomb base behavior and provide an engineering tool for application development. (paper)

  19. Exploration of mechanisms underlying the strain-rate-dependent mechanical property of single chondrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Trung Dung; Gu, YuanTong, E-mail: yuantong.gu@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland (Australia)

    2014-05-05

    Based on the characterization by Atomic Force Microscopy, we report that the mechanical property of single chondrocytes has dependency on the strain-rates. By comparing the mechanical deformation responses and the Young's moduli of living and fixed chondrocytes at four different strain-rates, we explore the deformation mechanisms underlying this dependency property. We found that the strain-rate-dependent mechanical property of living cells is governed by both of the cellular cytoskeleton and the intracellular fluid when the fixed chondrocytes are mainly governed by their intracellular fluid, which is called the consolidation-dependent deformation behavior. Finally, we report that the porohyperelastic constitutive material model which can capture the consolidation-dependent behavior of both living and fixed chondrocytes is a potential candidature to study living cell biomechanics.

  20. Opto-acoustic microscopy reveals adhesion mechanics of single cells

    Science.gov (United States)

    Abi Ghanem, Maroun; Dehoux, Thomas; Liu, Liwang; Le Saux, Guillaume; Plawinski, Laurent; Durrieu, Marie-Christine; Audoin, Bertrand

    2018-01-01

    Laser-generated GHz-ultrasonic-based technologies have shown the ability to image single cell adhesion and stiffness simultaneously. Using this new modality, we here demonstrate quantitative indicators to investigate contact mechanics and adhesion processes of the cell. We cultured human cells on a rigid substrate, and we used an inverted pulsed opto-acoustic microscope to generate acoustic pulses containing frequencies up to 100 GHz in the substrate. We map the reflection of the acoustic pulses at the cell-substrate interface to obtain images of the acoustic impedance of the cell, Zc, as well as of the stiffness of the interface, K, with 1 μm lateral resolution. Our results show that the standard deviation ΔZc reveals differences between different cell types arising from the multiplicity of local conformations within the nucleus. From the distribution of K-values within the nuclear region, we extract a mean interfacial stiffness, Km, that quantifies the average contact force in areas of the cell displaying weak bonding. By analogy with classical contact mechanics, we also define the ratio of the real to nominal contact areas, Sr/St. We show that Km can be interpreted as a quantitative indicator of passive contact at metal-cell interfaces, while Sr/St is sensitive to active adhesive processes in the nuclear region. The ability to separate the contributions of passive and active adhesion processes should allow gaining insight into cell-substrate interactions, with important applications in tissue engineering.

  1. [Liver enzymes elevation: etiologic study and efficiency of a single-act office visit].

    Science.gov (United States)

    Bendezú García, Rogger Álvaro; Casado Martín, Marta; Lázaro Sáez, Marta; Patrón Román, Gustavo Óliver; Gálvez Miras, Alejandra; Rodríguez Laiz, Gonzalo P; González Sánchez, Mercedes; Vega Sáenz, José Luis

    2013-01-01

    Liver enzyme (LE) elevation is a common finding in routine blood analysis. There is very little information on the most prevalent causes of these alterations in our population. In addition, a number of tests and several visits to the specialist are required to reach a diagnosis. For these reasons, we designed a protocol to streamline the evaluation of patients with LE elevations in a single-act office visit. From March 2008 until June 2010, we studied all patients with incidental LE elevation (isolated transaminase elevation, combined elevation of alkaline phosphatase [FA] and gamma-glutamyl transpeptidase [GGT], or isolated elevation of GGT) who were referred by their primary care physicians. At the time of referral, a complete biochemistry analysis was performed (LE, viral serology, autoantibodies, ceruloplasmin, iron metabolism, alpha-1-antitrypsin and thyroid hormones) and the patients underwent an abdominal ultrasound scan on the day of the office evaluation by the hepatologist. A total of 427 patients were included in our study. The most common cause of transaminase elevation was non-alcoholic fatty liver disease (NAFLD) (40%), followed by alcohol intake (17%), and hepatitis C virus infection (13%). Elevated GGT levels were most commonly related to NAFLD (30%), closely followed by alcohol intake (27%), and hepatotoxicity (8%). Combined elevation of GGT and FA was associated with NAFLD (21%), alcohol (17%), and hepatotoxicity (11%). Self-limited elevation was seen in 9% of the patients and we could not identify a definite cause in 11%. A definitive diagnosis was reached in 79% of the patients. The single-act office visit has proven to be efficient, yielding a diagnosis in most of the patients. The most common cause of elevated LE was NAFLD. Transaminase elevation must be confirmed before a more thorough work-up is started. Copyright © 2013 Elsevier España, S.L. and AEEH y AEG. All rights reserved.

  2. Mechanical Properties of a Single Electrospun Fiber and its Structures

    NARCIS (Netherlands)

    Gu, S.; Gu, Shuying; Wu, Qi-Lin; Ren, Jie; Vancso, Gyula J.

    2005-01-01

    A method to measure the Young's modulus of a single electrospun polyacrylonitrile (PAN) fiber is reported. The Young's modulus can be calculated from the force-displacement curves obtained by the bending of a single fiber attached to an atomic force microscopy (AFM) cantilever. It is suggested that

  3. Development of big five domains and facets in adulthood: mean-level age trends and broadly versus narrowly acting mechanisms.

    Science.gov (United States)

    Soto, Christopher J; John, Oliver P

    2012-08-01

    Data from a cross-sectional sample (N = 601 men and women) and a longitudinal sample (N = 125 women) were used to test hypotheses about the development of Big Five domains and facets from early adulthood through middle age. Analyses of mean-level age trends indicated that overall Agreeableness and Conscientiousness increased with age and that several facets showed distinctive trends that replicated across the samples. Cross-sectional analyses of trait intercorrelations and covariances indicated that interrelations between the Big Five domains, and between their more specific facets, were quite similar at older versus younger ages. Finally, longitudinal analyses of individual-level changes indicated that (a) different people's personalities changed in markedly different ways; (b) these changes were predominantly independent, rather than correlated, across Big Five domains; and (c) the pattern of change correlations between Big Five facets could be explained by the facets' interrelations at the first assessment time. Taken together, these results suggest that a complete understanding of personality development requires consideration of facet-level traits and that adult personality development is predominantly influenced by narrowly acting mechanisms that each affect a single Big Five domain, or a small cluster of related facets, rather than by broadly acting mechanisms that simultaneously affect previously independent traits. © 2011 The Authors. Journal of Personality © 2011, Wiley Periodicals, Inc.

  4. Piezoresistivity of mechanically drawn single-walled carbon nanotube (SWCNT) thin films-: mechanism and optimizing principle

    Science.gov (United States)

    Obitayo, Waris

    The individual carbon nanotube (CNT) based strain sensors have been found to have excellent piezoresistive properties with a reported gauge factor (GF) of up to 3000. This GF on the other hand, has been shown to be structurally dependent on the nanotubes. In contrast, to individual CNT based strain sensors, the ensemble CNT based strain sensors have very low GFs e.g. for a single walled carbon nanotube (SWCNT) thin film strain sensor, GF is ~1. As a result, studies which are mostly numerical/analytical have revealed the dependence of piezoresistivity on key parameters like concentration, orientation, length and diameter, aspect ratio, energy barrier height and Poisson ratio of polymer matrix. The fundamental understanding of the piezoresistive mechanism in an ensemble CNT based strain sensor still remains unclear, largely due to discrepancies in the outcomes of these numerical studies. Besides, there have been little or no experimental confirmation of these studies. The goal of my PhD is to study the mechanism and the optimizing principle of a SWCNT thin film strain sensor and provide experimental validation of the numerical/analytical investigations. The dependence of the piezoresistivity on key parameters like orientation, network density, bundle diameter (effective tunneling area), and length is studied, and how one can effectively optimize the piezoresistive behavior of a SWCNT thin film strain sensors. To reach this goal, my first research accomplishment involves the study of orientation of SWCNTs and its effect on the piezoresistivity of mechanically drawn SWCNT thin film based piezoresistive sensors. Using polarized Raman spectroscopy analysis and coupled electrical-mechanical test, a quantitative relationship between the strain sensitivity and SWCNT alignment order parameter was established. As compared to randomly oriented SWCNT thin films, the one with draw ratio of 3.2 exhibited ~6x increase on the GF. My second accomplishment involves studying the

  5. The Role Of Soft Law Acts In The Mechanism Of Functioning Of International Organizations

    Directory of Open Access Journals (Sweden)

    Olga N. Shpakovych

    2014-12-01

    Full Text Available Present article focuses on the norms of soft law in the framework of international organizations. Today majority of scientists become an interesting phenomenon decision of international organizations which are increasingly sound as a category of "soft law" and its influence on the development of international law in general. International organizations cease to be the "second" subject of international law, and if you have not won the first place, it is only a matter of time. In the article the role of soft law in the mechanism of international organizations functioning are shown, the legal nature and impact of these acts on the member states. In our opinion, norms of "soft law", as a rule, contained in resolutions of international organizations are non-binding and do not formally bind member states. Norms of "soft law" are often adheres by the states and moreover are implemented into the national legal systems by incorporating similar in content standards into the national legislation. This is due to the fact that norms of "soft law" has a weight of moral and political significance and, as a rule, are created by organizations that have a considerable authority. Jurists generally distinguish two kinds of acts of recommendatory force: model acts (laws and recommended acts which are not model, adopted in the framework of international organizations. In this connection the question of each mentioned method influence on the legislation of state. In our opinion, one of distinguishing features of the model recommendatory acts has is quite limited influence on the law of states and a narrow scope. At the same time, recommendatory acts of some specialized international organizations have a more complex effect on the development of national legislation, contain the highest level of standards, and as well develop international treaty provisions.

  6. Physical mechanisms of single-event effects in advanced microelectronics

    International Nuclear Information System (INIS)

    Schrimpf, Ronald D.; Weller, Robert A.; Mendenhall, Marcus H.; Reed, Robert A.; Massengill, Lloyd W.

    2007-01-01

    The single-event error rate in advanced semiconductor technologies can be estimated more accurately than conventional methods by using simulation based on accurate descriptions of a large number of individual particle interactions. The results can be used to select the ion types and energies for accelerator testing and to identify situations in which nuclear reactions will contribute to the error rate

  7. Coupling of single quantum emitters to plasmons propagating on mechanically etched wires

    DEFF Research Database (Denmark)

    Kumar, Shailesh; Huck, Alexander; Lu, Ying-Wei

    2013-01-01

    We demonstrate the coupling of a single nitrogen vacancy center in a nanodiamond to propagating plasmonic modes of mechanically etched silver nanowires. The mechanical etch is performed on single crystalline silver nanoplates by the tip of an atomic force microscope cantilever to produce wires...

  8. Failure mechanisms in single-point incremental forming of metals

    DEFF Research Database (Denmark)

    Silva, Maria B.; Nielsen, Peter Søe; Bay, Niels

    2011-01-01

    The last years saw the development of two different views on how failure develops in single-point incremental forming (SPIF). Today, researchers are split between those claiming that fracture is always preceded by necking and those considering that fracture occurs with suppression of necking. Eac...... and involves independent determination of formability limits by necking and fracture using tensile and hydraulic bulge tests in conjunction with SPIF of benchmark shapes under laboratory conditions.......The last years saw the development of two different views on how failure develops in single-point incremental forming (SPIF). Today, researchers are split between those claiming that fracture is always preceded by necking and those considering that fracture occurs with suppression of necking. Each...... on formability limits and development of fracture. The unified view conciliates the aforementioned different explanations on the role of necking in fracture and is consistent with the experimental observations that have been reported in the past years. The work is performed on aluminium AA1050-H111 sheets...

  9. Mechanisms of photoconduction degradation in cadmium-sulfide single crystals

    International Nuclear Information System (INIS)

    Burlak, A.V.; Ignatov, A.V.; Serdyuk, V.V.; Furlej, A.I.

    1987-01-01

    Calculation of the kinetics of degradation in photosensitive semiconductors of A 2 B 6 group is presented. It enables to consider the mechanism of photoconduction degradation ( PD ) on the basis of experimental dependences of photoconduction on time, mesured at diffeent temperatures and intensities of exciting light. Experimental investigations of PD were conducted with copper alloyed CdS volumetric crystals. It was concluded that PD in studied samples was conditioned by small donor ( Cdi ) depature to sinks

  10. Mechanism of action of direct-acting antiviral agents in treatment of chronic hepatitis C

    Directory of Open Access Journals (Sweden)

    WEN Xiaoyu

    2016-09-01

    Full Text Available With the development and launch of direct-acting antiviral agents (DAAs in the world in recent years, therapeutic regimens for chronic hepatitis C are constantly evolving. DAAs will also be launched in China in the near future. DAAs mainly target at the non-structural proteins of HCV and can inhibit HCV RNA replication. This article introduces the targets, mechanism of action, and resistance characteristics of different DAAs, as well as their current research and development in China and the results of phase Ⅲ clinical studies, in order to provide a reference for combined therapeutic strategies with DAAs in the treatment for chronic hepatitis C.

  11. Integration of Plasticity Mechanisms within a Single Sensory Neuron of C. elegans Actuates a Memory.

    Science.gov (United States)

    Hawk, Josh D; Calvo, Ana C; Liu, Ping; Almoril-Porras, Agustin; Aljobeh, Ahmad; Torruella-Suárez, María Luisa; Ren, Ivy; Cook, Nathan; Greenwood, Joel; Luo, Linjiao; Wang, Zhao-Wen; Samuel, Aravinthan D T; Colón-Ramos, Daniel A

    2018-01-17

    Neural plasticity, the ability of neurons to change their properties in response to experiences, underpins the nervous system's capacity to form memories and actuate behaviors. How different plasticity mechanisms act together in vivo and at a cellular level to transform sensory information into behavior is not well understood. We show that in Caenorhabditis elegans two plasticity mechanisms-sensory adaptation and presynaptic plasticity-act within a single cell to encode thermosensory information and actuate a temperature preference memory. Sensory adaptation adjusts the temperature range of the sensory neuron (called AFD) to optimize detection of temperature fluctuations associated with migration. Presynaptic plasticity in AFD is regulated by the conserved kinase nPKCε and transforms thermosensory information into a behavioral preference. Bypassing AFD presynaptic plasticity predictably changes learned behavioral preferences without affecting sensory responses. Our findings indicate that two distinct neuroplasticity mechanisms function together through a single-cell logic system to enact thermotactic behavior. VIDEO ABSTRACT. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Crystallization and mechanical properties of functionalized single-walled carbon nanotubes/polyvinylidene fluoride composites

    DEFF Research Database (Denmark)

    Ma, Jing; Iftekharul Haque, Rubaiyet; Larsen, Mikael

    2012-01-01

    Single-walled carbon nanotubes were purified and functionalized by nitric acid and octadecylamine. Raman and Fourier transform infrared spectroscopy were used to characterize the functionalization of the single-walled carbon nanotubes. Polyvinylidene flouride nanocomposites containing 1 wt......% purified or functionalized single-walled carbon nanotubes were prepared by solution blending and injection molding. The dispersion of different carbon nanotubes in dimethylformamide and in polyvinylidene flouride has been investigated. Mechanical properties show that adding single-walled carbon nanotubes...

  13. Operation analysis of a Chebyshev-Pantograph leg mechanism for a single DOF biped robot

    Science.gov (United States)

    Liang, Conghui; Ceccarelli, Marco; Takeda, Yukio

    2012-12-01

    In this paper, operation analysis of a Chebyshev-Pantograph leg mechanism is presented for a single degree of freedom (DOF) biped robot. The proposed leg mechanism is composed of a Chebyshev four-bar linkage and a pantograph mechanism. In contrast to general fully actuated anthropomorphic leg mechanisms, the proposed leg mechanism has peculiar features like compactness, low-cost, and easy-operation. Kinematic equations of the proposed leg mechanism are formulated for a computer oriented simulation. Simulation results show the operation performance of the proposed leg mechanism with suitable characteristics. A parametric study has been carried out to evaluate the operation performance as function of design parameters. A prototype of a single DOF biped robot equipped with two proposed leg mechanisms has been built at LARM (Laboratory of Robotics and Mechatronics). Experimental test shows practical feasible walking ability of the prototype, as well as drawbacks are discussed for the mechanical design.

  14. A novel experimental mechanics method for measuring the light pressure acting on a solar sail membrane

    Science.gov (United States)

    Shi, Aiming; Jiang, Li; Dowell, Earl H.; Qin, Zhixuan

    2017-02-01

    Solar sail is a high potential `sailing craft' for interstellar exploration. The area of the first flight solar sail demonstrator named "IKAROS" is 200 square meters. Future interplanetary missions will require solar sails at least on the order of 10000 square meters (or larger). Due to the limitation of ground facilities, the size of experimental sample should not be large. Furthermore the ground experiments have to be conducted in gravitational field, so the gravity effect must be considered in a ground test. To obtain insight into the solar sail membrane dynamics, a key membrane flutter (or limit cycle oscillations) experiment with light forces acting on it must be done. But one big challenge is calibrating such a tiny light force by as a function of the input power. In this paper, a gravity-based measuring method for light pressure acting on membrane is presented. To explain the experimental principle, an ideal example of a laser beam with expanders and a metal film is studied. Based on calculations, this experimental mechanics method for calibrating light pressure with an accuracy of 0.01 micro-Newton may be realized by making the light force balance the gravity force on the metal films. This gravity-based measuring method could not only be applied to study the dynamics characteristics of solar sail membrane structure with different light forces, but could also be used to determine more accurate light forces/loads acting on solar sail films and hence to enhance the determination of the mechanical properties of the solar sail membrane structure.

  15. A Fast and Self-Acting Release-Caging-Mechanism for Actively Driven Drop Tower Systems

    Science.gov (United States)

    Gierse, Andreas; Kaczmarczik, Ulrich; Greif, Andreas; Selig, Hanns; von Kampen, Peter; Könemann, Thorben; Lämmerzahl, Claus

    2017-10-01

    Today's and future scientific research programs ask for high quality microgravity conditions of 10-6 g on ground combined with high repetition rates of 100 flights per day or more. Accordingly, a new type of drop tower, the GraviTower Bremen, (GTB), has been suggested and is currently under development. As a first stage of development, a GTB-Prototype (GTB-Pro) has been designed which uses an active rope drive to accelerate a slider/drag shield and an experiment therein on a vertical parabola. During the free fall phase, the experiment is decoupled from the slider by a self-acting Release-Caging-Mechanism (RCM). Our prototype will provide 2.5 s of microgravity for experiments of up to 500 kg for at least 100 times per day. In this article, the final concept of the engineering of the active rope drive and the RCM are presented in detail. Based on extensive simulations aiming at an optimization of the whole system we developed a hydraulic rope drive system with minimized vibrational amplitude and low number of eigenfrequencies. The RCM achieves a very fast (≤ 0.1 s) self-acting release of the experiment from the slider by making use of the dynamics of the hydraulic rope drive. Furthermore, passive hydraulic stop dampers in the RCM build a passive and self-acting recoupling mechanism. This system is optimized for a fast decoupling to compensate for the time limitation posed by the chosen drive technology. The simulations included a comparison of different drive technologies, physical effects like the Coriolis force, and the dynamics of the RCM system itself.

  16. Conduction Mechanisms and Structure of Ionomeric Single-Ion Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Ralph H. [Pennsylvania State Univ., University Park, PA (United States); Maranas, Janna K. [Pennsylvania State Univ., University Park, PA (United States); Mueller, Karl T. [Pennsylvania State Univ., University Park, PA (United States); Runt, James [Pennsylvania State Univ., University Park, PA (United States); Winey, Karen I. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    2015-03-01

    Our team has designed using DFT (Gaussian) and synthesized low glass transition temperature single-ion conductors that are either polyanions that conduct small cations Li+, Na+, Cs+ or polycations that conduct small anions F-, OH-, Br-. We utilize a wide range of complimentary experimental materials characterization tools to understand ion transport; differential scanning calorimetry, dielectric relaxation spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, linear viscoelasticity, X-ray scattering and molecular dynamics simulations. The glass transition temperature Tg needs to be as low as possible to facilitate ion transport, so the nonionic parts of the polymer need to be polar, flexible and have strong solvation interactions with the ions. The lowest Tg we have managed for polyanions conducting Li+ is -60 °C. In contrast, polysiloxanes with PEO side chains and tetrabutylphosphonium cationic side groups have Tg ≈ -75 °C that barely increases with ion content, as anticipated by DFT. A survey of all polyanions in the literature suggests that Tg < -80 °C is needed to achieve the 10-4 S/cm conductivity needed for battery separators.

  17. Understanding the kinetic mechanism of RNA single base pair formation.

    Science.gov (United States)

    Xu, Xiaojun; Yu, Tao; Chen, Shi-Jie

    2016-01-05

    RNA functions are intrinsically tied to folding kinetics. The most elementary step in RNA folding is the closing and opening of a base pair. Understanding this elementary rate process is the basis for RNA folding kinetics studies. Previous studies mostly focused on the unfolding of base pairs. Here, based on a hybrid approach, we investigate the folding process at level of single base pairing/stacking. The study, which integrates molecular dynamics simulation, kinetic Monte Carlo simulation, and master equation methods, uncovers two alternative dominant pathways: Starting from the unfolded state, the nucleotide backbone first folds to the native conformation, followed by subsequent adjustment of the base conformation. During the base conformational rearrangement, the backbone either retains the native conformation or switches to nonnative conformations in order to lower the kinetic barrier for base rearrangement. The method enables quantification of kinetic partitioning among the different pathways. Moreover, the simulation reveals several intriguing ion binding/dissociation signatures for the conformational changes. Our approach may be useful for developing a base pair opening/closing rate model.

  18. Single-step brazing process for mono-block joints and mechanical testing

    International Nuclear Information System (INIS)

    Casalegno, V.; Ferraris, M.; Salvo, M.; Rizzo, S.; Merola, M.

    2007-01-01

    Full text of publication follows: Plasma facing components act as actively cooled thermal shields to sustain thermal and particle loads during normal and transient operations in ITER (International Thermonuclear Experimental Reactor). The plasma-facing layer is referred to as 'armour', which is made of either carbon fibre reinforced carbon composite (CFC) or tungsten (W). CFC is the reference design solution for the lower part of the vertical target of the ITER divertor. The armour is joined onto an actively cooled substrate, the heat sink, made of precipitation hardened copper alloy CuCrZr through a thin pure copper interlayer to decrease, by plastic deformation, the joint interface stresses; in fact, the CFC to Cu joint is affected by the CTE mismatch between the ceramic and metallic material. A new method of joining CFC to copper and CFC/Cu to CuCrZr alloy was effectively developed for the flat-type configuration; the feasibility of this process also for mono-block geometry and the development of a procedure for testing mono-block-type mock-ups is described in this work. The mono-block configuration consists of copper alloy pipe shielded by CFC blocks. It is worth noting that in mono-block configuration, the large thermal expansion mismatch between CFC and copper alloy is more significant than for flat-tile configuration, due to curved interfaces. The joining technique foresees a single-step brazing process: the brazing of the three materials (CFC-Cu-CuCrZr) can be performed in a single heat treatment using the same Cu/Ge based braze. The composite surface was modified by solid state reaction with chromium with the purpose of increasing the wettability of CFC by the brazing alloy. The CFC substrate reacts with Cr which, forming a carbide layer, allows a large reduction of the contact angle; then, the brazing of CFC to pure copper and pure copper to CuCrZr by the same treatment is feasible. This process allows to obtain good joints using a non-active brazing

  19. Draft forces prediction model for standard single tines by using principles of soil mechanics and soil profile evaluation

    Directory of Open Access Journals (Sweden)

    Amer Khalid Ahmed Al-Neama

    2017-06-01

    Full Text Available This paper explains a model to predict the draft force acting on varying standard single tines by using principles of soil mechanics and soil profile evaluation. Draft force (Fd measurements were made with four standard single tines comprising Heavy Duty, Double Heart, Double Heart with Wings and Duck Foot. Tine widths were 6.5, 13.5, 45 and 40 cm, respectively. The test was conducted in a soil bin with sandy loam soil. The effects of forward speeds and working depths on draft forces were investigated under controlled lab conditions. Results were evaluated based on a prediction model. A good correlation between measured and predicted Fd values for all tines with an average absolute variation less than 15 % was found.

  20. Mechanisms of gravitropism in single-celled systems

    Science.gov (United States)

    Greuel, Nicole; Braun, Markus; Hauslage, Jens; Wiemann, Katharina

    pressure exerted by sedimented statoliths. Instead, the experiments provide evidence that graviperception depends on direct interactions between statoliths and a yet unknown gravireceptor.Graviperception in higher plant statocytes was also found to be not dependent on mechanical pressure but on direct interactions between gravireceptors and statoliths. In contrast to Chara rhizoids, however, the actin system of higher plant statocytes is not essentially required for gravity-sensing. Parabolic flight experiments and ground controls indicated that disruption of the actin cytoskeleton in root statocytes by using Latrunculin B results in an increased gravisensitivity and in a promoted gravitropic curvature rather than in an inhibition. It is speculated that the actomyosin system in statocytes has a fine-tuning function in the early phases of gravity sensing. Actin in higher plant statocytes may be required to optimize statolith-receptor interactions and to keep the sensing system highly sensitive on one hand, but on the other hand actomyosin-statolith interactions seem to avoid unfavourable responses to only transient stimuli.Investigating the unicellular characean rhizoid has greatly enhanced our understanding of gravity sensing processes in plants and there is increasing evidence that higher plants and characean rhizoids share common processes in the signalling pathway of gravity-oriented growth.

  1. Design of Electro-Mechanical Dual-Acting Pulley Continuously Variable Transmission

    Directory of Open Access Journals (Sweden)

    K.B. Tawi

    2015-06-01

    Full Text Available Pulley-based continuously variable transmission (CVT with a metal pushing V-belt is fast becoming the preferred choice for global carmakers due to its potential particularly in terms of fuel efficiency thanks to its continuous and wide ratio range. Nevertheless, the existing CVTs still face the issues of high power consumption from the engine because of the application of an electro-hydro-mechanical (EHM actuation system for its ratio changing process and clamping force mechanism. To address this issue, researchers from Universiti Teknologi Malaysia have successfully developed the prototype of an electro-mechanical dual-acting pulley continuously variable transmission (EMDAP CVT for automotive applications. The prototype of EMDAP CVT is developed for a maximum input torque of 160 Nm with the application of a metal pushing V-belt. The results from the testing prove that the prototype can vary its ratio from 2.8 to 0.6 and no continuous power is required to maintain a constant CVT ratio. These results suggest that the prototype is workable and future testing in a real car is possible.

  2. Expression of Ski can act as a negative feedback mechanism on retinoic acid signaling.

    Science.gov (United States)

    Melling, Meaghan A; Friendship, Charlotte R C; Shepherd, Trevor G; Drysdale, Thomas A

    2013-06-01

    Retinoic acid signaling is essential for many aspects of early development in vertebrates. To control the levels of signaling, several retinoic acid target genes have been identified that act to suppress retinoic acid signaling in a negative feedback loop. The nuclear protein Ski has been extensively studied for its ability to suppress transforming growth factor-beta (TGF-β) signaling but has also been implicated in the repression of retinoic acid signaling. We demonstrate that ski expression is up-regulated in response to retinoic acid in both early Xenopus embryos and in human cell lines. Blocking retinoic acid signaling using a retinoic acid antagonist results in a corresponding decrease in the levels of ski mRNA. Finally, overexpression of SKI in human cells results in reduced levels of CYP26A1 mRNA, a known target of retinoic acid signaling. Our results, coupled with the known ability of Ski to repress retinoic acid signaling, demonstrate that Ski expression is a novel negative feedback mechanism acting on retinoic acid signaling. Copyright © 2013 Wiley Periodicals, Inc.

  3. Beta-Adrenergic Receptors and Mechanisms in Asthma: The New Long-Acting Beta-Agonists

    Directory of Open Access Journals (Sweden)

    Robert G Townley

    1996-01-01

    Full Text Available The objective is to review β-adrenergic receptors and mechanisms in the immediate and late bronchial reaction in asthma and the new long-acting β-agonist. This will be discussed in light of the controversy of the potential adverse effect of regular use of long-acting β-agonists. We studied the effect of formoterol on the late asthmatic response (LAR and airway inflammation in guinea-pigs. Formoterol suppressed the LAR, antigen-induced airway inflammation and hyperresponsiveness, although isoproterenol failed to inhibit these parameters. β-Adrenergic hyporesponsiveness, and cholinergic and a- adrenergic hyperresponsiveness have been implicated in the pathogenesis of asthma. A decrease in β-adrenoreceptor function can result either from exogenously administered β-agonist or from exposure to allergens resulting in a late bronchial reaction. There is increasing evidence that eosinophils, macrophages, and lymphocytes which are of primary importance in the late bronchial reaction are also modulated by β2- adrenoreceptors. In functional studies of guinea-pig or human isolated trachea and lung parenchyma, PAF and certain cytokines significantly reduced the potency of isoproterenol to reverse methacholine- or histamine-induced contraction. The effect of glucocorticoids on pulmonary β-adrenergic receptors and responses suggests an important role for glucocorticoids to increase β-adrenergic receptors and responsiveness.

  4. Double-slit experiment with single wave-driven particles and its relation to quantum mechanics

    DEFF Research Database (Denmark)

    Andersen, Anders Peter; Madsen, Jacob; Reichelt, Christian Günther

    2015-01-01

    even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes......¨dinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can...... not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics....

  5. Bio imaging of intracellular NO production in single bone cells after mechanical stimulation

    NARCIS (Netherlands)

    Vatsa, A.; Mizuno, D.; Smit, T.H.; Schmidt, C.; Mac Kintosh, F.C.; Klein-Nulend, J.

    2006-01-01

    We show the intracellular upregulation of NO production after mechanical stimulation, an essential chemical signal in bone remodeling. This is done in real time using the fluorescent chromophore DAR-4M AM. Differences in cellular response to mechanical stimulation of different regions of a single

  6. Discovery and Characterization of ACT-451840: an Antimalarial Drug with a Novel Mechanism of Action.

    Science.gov (United States)

    Boss, Christoph; Aissaoui, Hamed; Amaral, Nathalie; Bauer, Aude; Bazire, Stephanie; Binkert, Christoph; Brun, Reto; Bürki, Cédric; Ciana, Claire-Lise; Corminboeuf, Olivier; Delahaye, Stephane; Dollinger, Claire; Fischli, Christoph; Fischli, Walter; Flock, Alexandre; Frantz, Marie-Céline; Girault, Malory; Grisostomi, Corinna; Friedli, Astrid; Heidmann, Bibia; Hinder, Claire; Jacob, Gael; Le Bihan, Amelie; Malrieu, Sophie; Mamzed, Saskia; Merot, Aurelien; Meyer, Solange; Peixoto, Sabrina; Petit, Nolwenn; Siegrist, Romain; Trollux, Julien; Weller, Thomas; Wittlin, Sergio

    2016-09-20

    More than 40 % of the world's population is at risk of being infected with malaria. Most malaria cases occur in the countries of sub-Saharan Africa, Central and South America, and Asia. Resistance to standard therapy, including artemisinin combinations, is increasing. There is an urgent need for novel antimalarials with new mechanisms of action. In a phenotypic screen, we identified a series of phenylalanine-based compounds that exhibit antimalarial activity via a new and yet unknown mechanism of action. Our optimization efforts culminated in the selection of ACT-451840 [(S,E)-N-(4-(4-acetylpiperazin-1-yl)benzyl)-3-(4-(tert-butyl)phenyl)-N-(1-(4-(4-cyanobenzyl)piperazin-1-yl)-1-oxo-3-phenylpropan-2-yl)acrylamide] for clinical development. Herein we describe our optimization efforts from the screening hit to the potential drug candidate with respect to antiparasitic activity, drug metabolism and pharmacokinetics (DMPK) properties, and in vivo pharmacological efficacy. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Analysis of the impacts of mechanical errors on the RF performance of a single spoke cavity

    International Nuclear Information System (INIS)

    Yao Zhongyuan; Lu Xiangyang; Zhang Baocheng; Quan Shengwen; He Feisi; Zhao Kui

    2010-01-01

    Mechanical errors can not be avoided in fabrication. They will cause geometry errors and have impacts on the cavity performance. This paper systematically analyzes the impacts of mechanical errors on the RF performance of Peking University single spoke cavity. The various kinds of shape and size errors are considered, the influences on the resonation frequency and field flatness are studied by numerical simulation and the theoretical models are analyzed. The results show that the single spoke cavity is robust with respect to the mechanical tolerance. It also indicates the most essential factors for fabrication. (authors)

  8. Controlled switching of single-molecule junctions by mechanical motion of a phenyl ring

    Directory of Open Access Journals (Sweden)

    Yuya Kitaguchi

    2015-10-01

    Full Text Available Mechanical methods for single-molecule control have potential for wide application in nanodevices and machines. Here we demonstrate the operation of a single-molecule switch made functional by the motion of a phenyl ring, analogous to the lever in a conventional toggle switch. The switch can be actuated by dual triggers, either by a voltage pulse or by displacement of the electrode, and electronic manipulation of the ring by chemical substitution enables rational control of the on-state conductance. Owing to its simple mechanics, structural robustness, and chemical accessibility, we propose that phenyl rings are promising components in mechanical molecular devices.

  9. SSO - Single-Sign-On Profile: Authentication Mechanisms Version 2.0

    Science.gov (United States)

    Taffoni, Giuliano; Schaaf, André; Rixon, Guy; Major, Brian; Taffoni, Giuliano

    2017-05-01

    Approved client-server authentication mechanisms are described for the IVOA single-sign-on profile: No Authentication; HTTP Basic Authentication; TLS with passwords; TLS with client certificates; Cookies; Open Authentication; Security Assertion Markup Language; OpenID. Normative rules are given for the implementation of these mechanisms, mainly by reference to pre-existing standards. The Authorization mechanisms are out of the scope of this document.

  10. Single methyl groups can act as toggle switches to specify transmembrane protein-protein interactions

    DEFF Research Database (Denmark)

    He, Li; Steinocher, Helena; Shelar, Ashish

    2017-01-01

    of leucine and isoleucine (called LIL traptamers) that specifically activate the erythropoietin receptor (EPOR) in mouse cells to confer growth factor independence. We discovered that the placement of a single side chain methyl group at specific positions in a traptamer determined whether it associated......Transmembrane domains (TMDs) engage in protein-protein interactions that regulate many cellular processes, but the rules governing the specificity of these interactions are poorly understood. To discover these principles, we analyzed 26-residue model transmembrane proteins consisting exclusively...... productively with the TMD of the human EPOR, the mouse EPOR, or both receptors. Association of the traptamers with the EPOR induced EPOR oligomerization in an orientation that stimulated receptor activity. These results highlight the high intrinsic specificity of TMD interactions, demonstrate that a single...

  11. Investigating and improving student understanding of quantum mechanics in the context of single photon interference

    Science.gov (United States)

    Marshman, Emily; Singh, Chandralekha

    2017-06-01

    Single photon experiments involving a Mach-Zehnder interferometer can illustrate the fundamental principles of quantum mechanics, e.g., the wave-particle duality of a single photon, single photon interference, and the probabilistic nature of quantum measurement involving single photons. These experiments explicitly make the connection between the abstract quantum theory and concrete laboratory settings and have the potential to help students develop a solid grasp of the foundational issues in quantum mechanics. Here we describe students' conceptual difficulties with these topics in the context of Mach-Zehnder interferometer experiments with single photons and how the difficulties found in written surveys and individual interviews were used as a guide in the development of a Quantum Interactive Learning Tutorial (QuILT). The QuILT uses an inquiry-based approach to learning and takes into account the conceptual difficulties found via research to help upper-level undergraduate and graduate students learn about foundational quantum mechanics concepts using the concrete quantum optics context. It strives to help students learn the basics of quantum mechanics in the context of single photon experiment, develop the ability to apply fundamental quantum principles to experimental situations in quantum optics, and explore the differences between classical and quantum ideas in a concrete context. We discuss the findings from in-class evaluations suggesting that the QuILT was effective in helping students learn these abstract concepts.

  12. Recovery Act : Near-Single-Crystalline Photovoltaic Thin Films on Polycrystalline, Flexible Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Venkat Selvamanickam; Alex Freundlich

    2010-11-29

    III-V photovoltaics have exhibited efficiencies above 40%, but have found only a limited use because of the high cost of single crystal substrates. At the other end of the spectrum, polycrystalline and amorphous thin film solar cells offer the advantage of low-cost fabrication, but have not yielded high efficiencies. Our program is based on single-crystalline-like thin film photovoltaics on polycrystalline substrates using biaxially-textured templates made by Ion Beam-Assisted Deposition (IBAD). MgO templates made by IBAD on flexible metal substrate have been successfully used for epitaxial growth of germanium films. In spite of a 4.5% lattice mismatch, heteroepitaxial growth of Ge was achieved on CeO2 that was grown on IBAD MgO template. Room temperature optical bandgap of the Ge films was identified at 0.67 eV indicating minimal residual strain. Refraction index and extinction coefficient values of the Ge films were found to match well with that measured from a reference Ge single crystal. GaAs has been successfully grown epitaxially on Ge on metal substrate by molecular beam epitaxy. RHEED patterns indicate self annihilation of antiphase boundaries and the growth of a single domain GaAs. The GaAs is found to exhibit strong photoluminescence signal and, an existence of a relatively narrow (FWHM~20 meV) band-edge excitons measured in this film indicates a good optoelectronic quality of deposited GaAs. While excellent epitaxial growth has been achieved in GaAs on flexible metal substrates, the defect density of the films as measured by High Resolution X-ray Diffraction and etch pit experiments showed a high value of 5 * 10^8 per cm^2. Cross sectional transmission electron microscopy of the multilayer architecture showed concentration of threading dislocations near the germanium-ceria interface. The defect density was found decrease as the Ge films were made thicker. The defects appear to originate from the MgO layer presumably because of large lattice mismatches

  13. Imaging Action Potential in Single Mammalian Neurons by Tracking the Accompanying Sub-Nanometer Mechanical Motion.

    Science.gov (United States)

    Yang, Yunze; Liu, Xian-Wei; Wang, Hui; Yu, Hui; Guan, Yan; Wang, Shaopeng; Tao, Nongjian

    2018-03-28

    Action potentials in neurons have been studied traditionally by intracellular electrophysiological recordings and more recently by the fluorescence detection methods. Here we describe a label-free optical imaging method that can measure mechanical motion in single cells with a sub-nanometer detection limit. Using the method, we have observed sub-nanometer mechanical motion accompanying the action potential in single mammalian neurons by averaging the repeated action potential spikes. The shape and width of the transient displacement are similar to those of the electrically recorded action potential, but the amplitude varies from neuron to neuron, and from one region of a neuron to another, ranging from 0.2-0.4 nm. The work indicates that action potentials may be studied noninvasively in single mammalian neurons by label-free imaging of the accompanying sub-nanometer mechanical motion.

  14. Retrocausation acting in the single-electron double-slit interference experiment

    Science.gov (United States)

    Hokkyo, Noboru

    The single electron double-slit interference experiment is given a time-symmetric interpretation and visualization in terms of the intermediate amplitude of transition between the particle source and the detection point. It is seen that the retarded (causal) amplitude of the electron wave expanding from the source shows an advanced (retrocausal) bifurcation and merging in passing through the double-slit and converges towards the detection point as if guided by the advanced (retrocausal) wave from the detected electron. An experiment is proposed to confirm the causation-retrocausation symmetry of the electron behavior by observing the insensitivity of the interference pattern to non-magnetic obstacles placed in the shadows of the retarded and advanced waves appearing on the rear and front sides of the double-slit.

  15. Relationships among the structural topology, bond strength, and mechanical properties of single-walled aluminosilicate nanotubes.

    Science.gov (United States)

    Liou, Kai-Hsin; Tsou, Nien-Ti; Kang, Dun-Yen

    2015-10-21

    Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.

  16. Estimation of turgor pressure through comparison between single plant cell and pressurized shell mechanics

    Science.gov (United States)

    Durand-Smet, P.; Gauquelin, E.; Chastrette, N.; Boudaoud, A.; Asnacios, A.

    2017-10-01

    While plant growth is well known to rely on turgor pressure, it is challenging to quantify the contribution of turgor pressure to plant cell rheology. Here we used a custom-made micro-rheometer to quantify the viscoelastic behavior of isolated plant cells while varying their internal turgor pressure. To get insight into how plant cells adapt their internal pressure to the osmolarity of their medium, we compared the mechanical behavior of single plant cells to that of a simple, passive, pressurized shell: a soccer ball. While both systems exhibited the same qualitative behavior, a simple mechanical model allowed us to quantify turgor pressure regulation at the single cell scale.

  17. Mass sensors with mechanical traps for weighing single cells in different fluids.

    Science.gov (United States)

    Weng, Yaochung; Delgado, Francisco Feijó; Son, Sungmin; Burg, Thomas P; Wasserman, Steven C; Manalis, Scott R

    2011-12-21

    We present two methods by which single cells can be mechanically trapped and continuously monitored within the suspended microchannel resonator (SMR) mass sensor. Since the fluid surrounding the trapped cell can be quickly and completely replaced on demand, our methods are well suited for measuring changes in cell size and growth in response to drugs or other chemical stimuli. We validate our methods by measuring the density of single polystyrene beads and Saccharomyces cerevisiae yeast cells with a precision of approximately 10(-3) g cm(-3), and by monitoring the growth of single mouse lymphoblast cells before and after drug treatment.

  18. Recovery Act: Hydroelectric Facility Improvement Project - Replacement of Current Mechanical Seal System with Rope Packing System

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Jessica D.

    2013-05-29

    On January 27, 2010 the City of North Little Rock, Arkansas received notification of the awarding of a Department of Energy (DOE) grant totaling $450,000 in funding from the American Recovery and Reinvestment Act (ARRA) under the Project Title: Recovery Act: Hydroelectric Facility Improvement Project – Automated Intake Clearing Equipment and Materials Management. The purpose of the grant was for improvements to be made at the City’s hydroelectric generating facility located on the Arkansas River. Improvements were to be made through the installation of an intake maintenance device (IMD) and the purchase of a large capacity wood grinder. The wood grinder was purchased in order to receive the tree limbs, tree trunks, and other organic debris that collects at the intake of the plant during high flow. The wood grinder eliminates the periodic burning of the waste material that is cleared from the intake and reduces any additional air pollution to the area. The resulting organic mulch has been made available to the public at no charge. Design discussion and planning began immediately and the wood grinder was purchased in July of 2010 and immediately put to work mulching debris that was gathered regularly from the intake of the facility. The mulch is currently available to the public for free. A large majority of the design process was spent in discussion with the Corps of Engineers to obtain approval for drawings, documents, and permits that were required in order to make changes to the structure of the powerhouse. In April of 2011, the City’s Project Engineer, who had overseen the application, resigned and left the City’s employ. A new Systems Mechanical Engineer was hired and tasked with overseeing the project. The transfer of responsibility led to a re-examination of the original assumptions and research upon which the grant proposal was based. At that point, the project went under review and a trip was booked for July 2011 to visit facilities that currently

  19. Overview and Design of self-acting pitch control mechanism for vertical axis wind turbine using multi body simulation approach

    DEFF Research Database (Denmark)

    Chougule, Prasad; Nielsen, Søren R.K.

    2014-01-01

    mechanism is given. A pitch control linkage mechanism for vertical axis wind turbine is modeled by multi-body approach using MSC Software. Aerodynamic loads are predicted from a mathematical model based on double multiple stream tube method. An appropriate airfoil which works at low Reynolds number...... is selected for blade design. It is also focused on commercialization of the vertical axis wind turbine which incorporates the self-acting pitch control system. These aerodynamic load model will be coupled with the multi-body model in future work for optimization of the pitch control linkage mechanism. A 500...... problem of self-start inability and has low power coefficient as compare to the horizontal axis wind turbine. These two problems can be eliminated by incorporating the blade pitching mechanism. So, in this paper overview of various pitch control systems is discussed and design of self-acting pitch...

  20. Strain-hardening in nano-structured single phase steels: mechanisms and control.

    Science.gov (United States)

    Bouaziz, O; Barbier, D

    2012-11-01

    The detrimental effect of grain size refinement on the strain hardening is highlighted in single phase steels. A physical based approach for understanding the underlying mechanisms is presented. In order to overcome this limitation a promising metallurgical route exploiting the thermal stability of mechanically induced twins in austenitic steels has been successfully applied to a stainless grade confirming the opportunity to get nano-structured alloys exhibiting high yield stress with high strain-hardening.

  1. Double-slit experiment with single wave-driven particles and its relation to quantum mechanics.

    Science.gov (United States)

    Andersen, Anders; Madsen, Jacob; Reichelt, Christian; Rosenlund Ahl, Sonja; Lautrup, Benny; Ellegaard, Clive; Levinsen, Mogens T; Bohr, Tomas

    2015-07-01

    In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006)] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

  2. Double-slit experiment with single wave-driven particles and its relation to quantum mechanics

    Science.gov (United States)

    Andersen, Anders; Madsen, Jacob; Reichelt, Christian; Rosenlund Ahl, Sonja; Lautrup, Benny; Ellegaard, Clive; Levinsen, Mogens T.; Bohr, Tomas

    2015-07-01

    In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006), 10.1103/PhysRevLett.97.154101] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

  3. Mechanical characterization and single asperity scratch behaviour of dry zinc and manganese phosphate coatings

    NARCIS (Netherlands)

    Ernens, D.; de Rooij, M. B.; Pasaribu, H. R.; van Riet, E.J.; van Haaften, W.M.; Schipper, D. J.

    The goal of this study is to characterise the mechanical properties of zinc and manganese phosphate coatings before and after running in. The characterization is done with nano-indentation to determine the individual crystal hardness and single asperity scratch tests to investigate the deformation

  4. Mechanism of DNA–binding loss upon single-point mutation in p53

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    provides an excellent prototype system to elucidate the different mechanisms underlying the loss in DNA binding affinity and specificity upon single point mutation because over 50% of all human cancers involve p53 mutations, which occur mostly in the sequence–specific DNA–binding central domain (residues 102–292, ...

  5. Comparison of Numerical Modelling of Degradation Mechanisms in Single Mode Optical Fibre Using MATLAB and VPIphotonics

    Directory of Open Access Journals (Sweden)

    Jana Sajgalikova

    2015-01-01

    Full Text Available Mathematical models for description of physical phenomena often use the statistical description of the individual phenomena and solve those using suitable methods. If we want to develop numerical model of optical communication system based on transmission through single mode optical fibres, we need to consider whole series of phenomena that affect various parts of the system. In the single-mode optical fibre we often encounter influence of chromatic dispersion and nonlinear Kerr effects. By observing various different degradation mechanisms, every numerical model should have its own limits, which fulfil more detailed specification. It is inevitable to consider them in evaluation. In this paper, we focus on numerical modelling of degradation mechanisms in single-mode optical fibre. Numerical solution of non-linear Schroedinger equation is performed by finite difference method applied in MATLAB environment and split-step Fourier method, which is implemented by VPIphotonics software.

  6. Mechanisms and Implications of Dual-Acting Methotrexate in Folate-Targeted Nanotherapeutic Delivery

    Directory of Open Access Journals (Sweden)

    Pamela T. Wong

    2015-01-01

    Full Text Available The rational design of a nanoplatform in drug delivery plays a crucial role in determining its targeting specificity and efficacy in vivo. A conventional approach relies on the surface conjugation of a nanometer-sized particle with two functionally distinct types of molecules, one as a targeting ligand, and the other as a therapeutic agent to be delivered to the diseased cell. However, an alternative simplified approach can be used, in which a single type of molecule displaying dual function as both a targeting ligand and therapeutic agent is conjugated to the nanoparticle. In this review, we evaluate the validity of this new strategy by using methotrexate, which displays multifunctional mechanisms of action. Methotrexate binds to the folate receptor, a surface biomarker frequently overexpressed in tumor cells, and also inhibits dihydrofolate reductase, an enzyme critical for cell survival and division. Thus we describe a series of fifth generation poly(amido amine dendrimers conjugated with methotrexate, and discuss several lines of evidence supporting the efficacy of this new platform strategy based on surface plasmon resonance spectroscopy, enzyme activity assays, and cell-based studies with folate receptor (+ KB cancer cells.

  7. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Mills

    2009-03-05

    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  8. Physics colloquium: Single-electron counting in quantum metrology and in statistical mechanics

    CERN Multimedia

    Geneva University

    2011-01-01

    GENEVA UNIVERSITY Ecole de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92olé   Lundi 17 octobre 2011 17h00 - Ecole de Physique, Auditoire Stueckelberg PHYSICS COLLOQUIUM « Single-electron counting in quantum metrology and in statistical mechanics » Prof. Jukka Pekola Low Temperature Laboratory, Aalto University Helsinki, Finland   First I discuss the basics of single-electron tunneling and its potential applications in metrology. My main focus is in developing an accurate source of single-electron current for the realization of the unit ampere. I discuss the principle and the present status of the so-called single- electron turnstile. Investigation of errors in transporting electrons one by one has revealed a wealth of observations on fundamental phenomena in mesoscopic superconductivity, including individual Andreev...

  9. Enhanced mechanical properties of single-walled carbon nanotubes due to chemical functionalization.

    Science.gov (United States)

    He, X Q; Kuang, Y D; Chen, C Y; Li, G Q

    2009-05-27

    Recent studies have shown that the chemical functionalization of carbon nanotubes weakens most of their mechanical properties such as the critical buckling force under compression and the critical buckling moment under torsion. However, the mechanical properties including the critical bending curvature and the critical bending moment of single-walled carbon nanotubes can be improved after functionalization as shown in this paper. The molecular mechanics simulations reveal that there exists an optimum functionalization degree at which the critical curvatures of the functionalized carbon nanotubes reaches its maximum value. The critical curvatures of the carbon nanotubes increase with increasing functionalization degree below the optimum value, while the critical curvatures change little as the functionalization degree is beyond the optimum value. The influences of the bending directions and the aspect ratios of the functionalized carbon nanotubes are also examined via molecular mechanics simulations.

  10. Single-molecule folding mechanism of an EF-hand neuronal calcium sensor

    DEFF Research Database (Denmark)

    Heiðarsson, Pétur Orri; Otazo, Mariela R.; Bellucci, Luca

    2013-01-01

    EF-hand calcium sensors respond structurally to changes in intracellular Ca2+ concentration, triggering diverse cellular responses and resulting in broad interactomes. Despite impressive advances in decoding their structure-function relationships, the folding mechanism of neuronal calcium sensors...... is still elusive. We used single-molecule optical tweezers to study the folding mechanism of the human neuronal calcium sensor 1 (NCS1). Two intermediate structures induced by Ca2+ binding to the EF-hands were observed during refolding. The complete folding of the C domain is obligatory for the folding...

  11. DNA-cisplatin binding mechanism peculiarities studied with single molecule stretching experiments

    Science.gov (United States)

    Crisafuli, F. A. P.; Cesconetto, E. C.; Ramos, E. B.; Rocha, M. S.

    2012-02-01

    We propose a method to determine the DNA-cisplatin binding mechanism peculiarities by monitoring the mechanical properties of these complexes. To accomplish this task, we have performed single molecule stretching experiments by using optical tweezers, from which the persistence and contour lengths of the complexes can be promptly measured. The persistence length of the complexes as a function of the drug total concentration in the sample was used to deduce the binding data, from which we show that cisplatin binds cooperatively to the DNA molecule, a point which so far has not been stressed in binding equilibrium studies of this ligand.

  12. Crowding by a single bar: probing pattern recognition mechanisms in the visual periphery.

    Science.gov (United States)

    Põder, Endel

    2014-11-06

    Whereas visual crowding does not greatly affect the detection of the presence of simple visual features, it heavily inhibits combining them into recognizable objects. Still, crowding effects have rarely been directly related to general pattern recognition mechanisms. In this study, pattern recognition mechanisms in visual periphery were probed using a single crowding feature. Observers had to identify the orientation of a rotated T presented briefly in a peripheral location. Adjacent to the target, a single bar was presented. The bar was either horizontal or vertical and located in a random direction from the target. It appears that such a crowding bar has very strong and regular effects on the identification of the target orientation. The observer's responses are determined by approximate relative positions of basic visual features; exact image-based similarity to the target is not important. A version of the "standard model" of object recognition with second-order features explains the main regularities of the data. © 2014 ARVO.

  13. Investigation of Chirality Selection Mechanism of Single Walled Carbon Nanotube-3

    Science.gov (United States)

    2017-12-14

    paper as a result of the grant titled: Synthesis of CNT forest with narrow diameter distribution from the Fe ion implanted wafer, Carbon , vol. 123, pp...Jin Park, Seung Min Kim*, and Kun-Hong Lee*, “Synthesis of CNT forest with narrow diameter distribution from the Fe ion implanted wafer”, Carbon ...AFRL-AFOSR-JP-TR-2017-0078 Investigation of Chirality Selection Mechanism of Single-Walled Carbon Nanotube-3 Seun Min Kim KOREA INSTITUTE OF SCIENCE

  14. Adaptive kanban control mechanism for a single-stage hybrid system

    Science.gov (United States)

    Korugan, Aybek; Gupta, Surendra M.

    2002-02-01

    In this paper, we consider a hybrid manufacturing system with two discrete production lines. Here the output of either production line can satisfy the demand for the same type of product without any penalties. The interarrival times for demand occurrences and service completions are exponentially distributed i.i.d. variables. In order to control this type of manufacturing system we suggest a single stage pull type control mechanism with adaptive kanbans and state independent routing of the production information.

  15. Solar project description for Zien Mechanical Contractors-I single family residence, Milwaukee, Wisconsin

    Science.gov (United States)

    Beers, D.

    1980-02-01

    The Zien Mechanical site is a single family residence located in Milwaukee, Wisconsin. The home has two separate solar energy systems: an air system for space heating and cooling; a liquid system to preheat the potable hot water. The space heating and cooling system design and operation modes are described. The space heating system is designed to apply approximately 44 percent of the space heating requirements for the 1388 square foot residence. Engineering drawings are provided and the performance evaluation instrumentation is described.

  16. Fabrication of single phase 2D homologous perovskite microplates by mechanical exfoliation

    Science.gov (United States)

    Li, Junze; Wang, Jun; Zhang, Yingjun; Wang, Haizhen; Lin, Gaoming; Xiong, Xuan; Zhou, Weihang; Luo, Hongmei; Li, Dehui

    2018-04-01

    The two-dimensional (2D) Ruddlesden-Popper type perovskites have attracted intensive interest for their great environmental stability and various potential optoelectronic applications. Fundamental understanding of the photophysical and electronic properties of the 2D perovskites with pure single phase is essential for improving the performance of the optoelectronic devices and designing devices with new architectures. Investigating the optical and electronic properties of these materials with pure single phase is required to obtain pure single phase 2D perovskites. Here, we report on an alternative approach to fabricate (C4H9NH3)2(CH3NH3) n-1Pb n I3n+1 microplates with pure single n-number perovskite phase for n  >  2 by mechanical exfoliation. Micro-photoluminescence and absorption spectroscopy studies reveal that the as-synthesized 2D perovskite plates for n  >  2 are comprised by dominant n-number phase and small inclusions of hybrid perovskite phases with different n values, which is supported by excitation power dependent photoluminescence. By mechanical exfoliation method, 2D perovskite microplates with the thickness of around 20 nm are obtained, which surprisingly have single n-number perovskite phase for n  =  2-5. In addition, we have demonstrated that the exfoliated 2D perovskite microplates can be integrated with other 2D layered materials such as boron nitride, and are able to be transferred to prefabricated electrodes for photodetections. Our studies not only provide a strategy to prepare 2D perovskites with a single n-number perovskite phase allowing us to extract the basic optical and electronic parameters of pure phase perovskites, but also demonstrate the possibility to integrate the 2D perovskites with other 2D layered materials to extend the device’s functionalities.

  17. Effects of specimen size and yttria concentration on mechanical properties of single crystalline yttria-stabilized tetragonal zirconia nanopillars

    Science.gov (United States)

    Zhang, Ning; Asle Zaeem, Mohsen

    2017-07-01

    The nanoscale plastic deformation of yttria-stabilized tetragonal zirconia (YSTZ) is highly dependent on the crystallographic orientations, i.e., dislocation is induced when the loading direction is 45° tilted to {111} and {101} slip planes, while tetragonal to monoclinic phase transformation dominates the plastic deformation when loading direction is perpendicular to the slip planes. This study investigates the effects of specimen size and yttria concentration on the mechanical response of single crystalline YSTZ nanopillars. Through uniaxial compression test, the smaller-is-stronger phenomenon is revealed in nanopillars deformed through a dislocation motion mechanism. Serrated stacking faults are observed in the smallest nanopillar, while neat primary slip plane forms in the largest nanopillar. In contrast, the larger-is-stronger relation is observed in nanopillars in which deformation is mediated by tetragonal to monoclinic phase transformation. It is noted that the ratio of transformed monoclinic phase to the remaining tetragonal phase is the highest in the smallest nanopillar. The strength of nanopillars is identified to decrease by increasing the amount of yttria due to the creation of more oxygen vacancies that act as weak points to facilitate dislocation motion and accelerate phase transformation.

  18. Single-stranded DNA fragments of insect-specific nuclear polyhedrosis virus act as selective DNA insecticides for gypsy moth control.

    Science.gov (United States)

    Oberemok, Volodymyr V; Skorokhod, Oleksii A

    2014-07-01

    This paper focuses on the DNA insecticides as a novel preparation against gypsy moth (Lymantria dispar) based on DNA fragments of the anti-apoptotic gene of its nuclear polyhedrosis virus. It was found that the external application of a solution with two single-stranded DNA fragments from BIR and RING domains of LdMNPV (L.dispar multicapsid nuclear polyhedrosis virus) IAP-3 (inhibitor of apoptosis) gene induces a significantly higher mortality of gypsy moth caterpillars in comparison with the application of the control solutions. This effect does not depend on the infection of caterpillars with LdMNPV. The results also show that DNA insecticides based on LdMNPV IAP-3 gene fragments can be selective in action, and at least are not harmful to tobacco hornworm (Manduca sexta) and black cutworm (Agrotis ipsilon). Part of the gypsy moth genome cloned with the fragments of BIR and RING domains of LdMNPV IAP-3 gene as primers, has an overlap with the corresponding part of the LdMNPV IAP-3 gene and L.dispar IAP-1 mRNA for an inhibitor of apoptosis protein with the high cover by query, allows assuming that we cloned a part of gypsy moth anti-apoptosis gene. This finding gives the grounding that proposed here DNA insecticides might act through the blocking of the mechanisms involved in post transcriptional expression of insect anti-apoptosis genes. The results show the insecticidal potential of the viral genome fragments that can be used to create safe and relatively fast-acting DNA insecticides to control the quantity of gypsy moth populations, important task for forestry and agriculture. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Overview and Design of self-acting pitch control mechanism for vertical axis wind turbine using multi body simulation approach

    International Nuclear Information System (INIS)

    Chougule, Prasad; Nielsen, Søren

    2014-01-01

    Awareness about wind energy is constantly growing in the world. Especially a demand for small scale wind turbine is increasing and various products are available in market. There are mainly two types of wind turbines, horizontal axis wind turbine and vertical axis wind turbines. Horizontal axis wind turbines are suitable for high wind speed whereas vertical axis wind turbines operate relatively low wind speed area. Vertical axis wind turbines are cost effective and simple in construction as compared to the horizontal axis wind turbine. However, vertical axis wind turbines have inherent problem of self-start inability and has low power coefficient as compare to the horizontal axis wind turbine. These two problems can be eliminated by incorporating the blade pitching mechanism. So, in this paper overview of various pitch control systems is discussed and design of self-acting pitch mechanism is given. A pitch control linkage mechanism for vertical axis wind turbine is modeled by multi-body approach using MSC Software. Aerodynamic loads are predicted from a mathematical model based on double multiple stream tube method. An appropriate airfoil which works at low Reynolds number is selected for blade design. It is also focused on commercialization of the vertical axis wind turbine which incorporates the self-acting pitch control system. These aerodynamic load model will be coupled with the multi-body model in future work for optimization of the pitch control linkage mechanism. A 500 Watt vertical axis wind turbine is designed and it is planned to implement the self-acting pitch control mechanism in real model

  20. Large Deflections Mechanical Analysis of a Suspended Single-Wall Carbon Nanotube under Thermoelectrical Loading

    Directory of Open Access Journals (Sweden)

    Assaf Ya'akobovitz

    2011-01-01

    Full Text Available Following the recent progress in integrating single-wall carbon nanotubes (SWCNTs into silicon-based micro-electromechanical systems (MEMS, new modeling tools are needed to predict their behavior under different loads, including thermal, electrical and mechanical. In the present study, the mechanical behavior of SWCNTs under thermoelectrical loading is analyzed using a large deflection geometrically nonlinear string model. The effect of the resistive heating was found to have a substantial influence on the SWCNTs behavior, including significant enhancement of the strain (up to the millistrains range and buckling due to the thermal expansion. The effect of local buckling sites was also studied and was found to enhance the local strain. The theoretical and numerical results obtained in the present study demonstrate the importance of resistive heating in the analysis of SWCNTs and provide an additional insight into the unique mechanics of suspended SWCNTs.

  1. Resistance to the macrolide antibiotic tylosin is conferred by single methylations at 23S rRNA nucleotides G748 and A2058 acting in synergy

    Science.gov (United States)

    Liu, Mingfu; Douthwaite, Stephen

    2002-01-01

    The macrolide antibiotic tylosin has been used extensively in veterinary medicine and exerts potent antimicrobial activity against Gram-positive bacteria. Tylosin-synthesizing strains of the Gram-positive bacterium Streptomyces fradiae protect themselves from their own product by differential expression of four resistance determinants, tlrA, tlrB, tlrC, and tlrD. The tlrB and tlrD genes encode methyltransferases that add single methyl groups at 23S rRNA nucleotides G748 and A2058, respectively. Here we show that methylation by neither TlrB nor TlrD is sufficient on its own to give tylosin resistance, and resistance is conferred by the G748 and A2058 methylations acting together in synergy. This synergistic mechanism of resistance is specific for the macrolides tylosin and mycinamycin that possess sugars extending from the 5- and 14-positions of the macrolactone ring and is not observed for macrolides, such as carbomycin, spiramycin, and erythromycin, that have different constellations of sugars. The manner in which the G748 and A2058 methylations coincide with the glycosylation patterns of tylosin and mycinamycin reflects unambiguously how these macrolides fit into their binding site within the bacterial 50S ribosomal subunit. PMID:12417742

  2. Morphological and mechanical characterization of composite calcite/SWCNT-COOH single crystals.

    Science.gov (United States)

    Calvaresi, Matteo; Falini, Giuseppe; Pasquini, Luca; Reggi, Michela; Fermani, Simona; Gazzadi, Gian Carlo; Frabboni, Stefano; Zerbetto, Francesco

    2013-08-07

    A growing number of classes of organic (macro)molecular materials have been trapped into inorganic crystalline hosts, such as calcite single crystals, without significantly disrupting their crystalline lattices. Inclusion of an organic phase plays a key role in enhancing the mechanical properties of the crystals, which are believed to share structural features with biogenic minerals. Here we report the synthesis and mechanical characterization of composite calcite/SWCNT-COOH single crystals. Once entrapped into the crystals SWCNT-COOH appeared both as aggregates of entangled bundles and nanoropes. Their observation was possible only after crystal etching, fracture or FIB (focused ion beam) cross-sectioning. SWCNT-COOHs occupied a small volume fraction and were randomly distributed into the host crystal. They did not strongly affect the crystal morphology. However, although the Young's modulus of composite calcite/SWCNT-COOH single crystals was similar to that of pure calcite their hardness increased by about 20%. Thus, SWCNT-COOHs provide an obstacle against the dislocation-mediated propagation of plastic deformation in the crystalline slip systems, in analogy with the well-known hardness increase in fiber-reinforced composites.

  3. Mechanical and microstructural characterization of single and double pass Aluminum AA6061 friction stir weld joints

    International Nuclear Information System (INIS)

    Othman, N H; Shah, L H; Ishak, M

    2015-01-01

    This study focuses on the effect of single pass (SP), double sided pass (DSP) and normal double pass (NDP) method on friction stir welding of aluminum AA6061. Two pieces of AA6061 alloy with thickness of 6 mm were friction stir welded by using conventional milling machine. The rotational speeds that were used in this study were 800 rpm, 1000 rpm and 1200 rpm, respectively. The welding speed is fixed to 100 mm/min. Microstructure observation of welded area was studied by using optical microscope. Tensile test and Vickers hardness test were used to evaluate the mechanical properties of this specimen. Mechanical property analysis results indicate that at low rotational speeds, defects such as surface lack of fill and tunneling in the welded area can be observed. Vickers hardness of specimens however did not vary much when rotational speed is varied. Welded specimens using single pass method shows higher tensile strength and hardness value compared to both double pass methods up to 180.61 MPa. Moreover, DSP showed better tensile test and hardness test compared to NDP method. The optimum parameters were found to be single pass method with 1200 rpm of rotational speed. Therefore economically sound to only perform SP method to obtain maximum tensile strength for AA6061 FSW with thickness of 6 mm. (paper)

  4. MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    V.S. Malyar

    2016-06-01

    Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.

  5. A Failure Criterion for Single-Walled Carbon Nanotubes Based on Molecular Mechanics

    Science.gov (United States)

    Avila, Antonio; Lacerda, Guilherme

    2008-03-01

    Single-walled carbon nanotubes (SWNT) are the natural choice for high performance materials. The problem, however, rises when the experimental data are compared against each other. The large variability of experimental data lead to development of a new set of numerical simulations called molecular mechanics, which is a ``symbiotic'' association of molecular dynamics and solid mechanics. This papers deals with a molecular mechanics simulations of single-walled carbon nanotubes. Three SWNT configurations and its combinations were simulated, i.e. armchair, zigzag and chiral. The failure criterion introduced is based on modified Morse's potential with dissociation energy of 124 Kcal/mol and an inflection point considered is around 13% of strain. The numerical data are in good agreement with data from Belytschko et al. (2002) where the failure occurred at 10.6% strain at 65.2 GPa of stress. To be able to identify the highest stress concentration region, one end of the SWNT all degrees-of-freedom were fixed and a prescribed axial displacement was applied at the opposite end. The Sadoc (chiral-chiral) configuration had the highest stress at the smallest chiral SWNT. For the Dunlap configuration (chiral-zigzag) the highest stress occurred at chiral part close to the pentagon location.

  6. Electrical properties and mechanical stability of anchoring groups for single-molecule electronics

    Directory of Open Access Journals (Sweden)

    Riccardo Frisenda

    2015-07-01

    Full Text Available We report on an experimental investigation of transport through single molecules, trapped between two gold nano-electrodes fabricated with the mechanically controlled break junction (MCBJ technique. The four molecules studied share the same core structure, namely oligo(phenylene ethynylene (OPE3, while having different aurophilic anchoring groups: thiol (SAc, methyl sulfide (SMe, pyridyl (Py and amine (NH2. The focus of this paper is on the combined characterization of the electrical and mechanical properties determined by the anchoring groups. From conductance histograms we find that thiol anchored molecules provide the highest conductance; a single-level model fit to current–voltage characteristics suggests that SAc groups exhibit a higher electronic coupling to the electrodes, together with better level alignment than the other three groups. An analysis of the mechanical stability, recording the lifetime in a self-breaking method, shows that Py and SAc yield the most stable junctions while SMe form short-lived junctions. Density functional theory combined with non-equlibrium Green’s function calculations help in elucidating the experimental findings.

  7. Single-nary philosophy for non-linear study of mechanics of materials

    International Nuclear Information System (INIS)

    Tran, C.

    2005-01-01

    Non-linear study of mechanics of materials is formulated in this paper as a problem of meta-intelligent system analysis. Non-linearity will be singled out as an important concept for understanding of high-order complex systems. Through single-nary thinking, which will be represented in this work, we introduce a modification of Aristotelian philosophy using modal logic and multi-valued logic (these logics we call 'high-order' logic). Next, non-linear cause - effect relations are expressed through non-additive measures and multiple-information aggregation principles based on fuzzy integration. The study of real time behaviors, required experiences and intuition, will be realized using truth measures (non-additive measures) and a procedure for information processing in intelligence levels. (author)

  8. Rings and rackets from single-wall carbon nanotubes: manifestations of mesoscale mechanics.

    Science.gov (United States)

    Wang, Yuezhou; Semler, Matthew R; Ostanin, Igor; Hobbie, Erik K; Dumitrică, Traian

    2014-11-21

    We combine experiments and distinct element method simulations to understand the stability of rings and rackets formed by single-walled carbon nanotubes assembled into ropes. Bending remains a soft deformation mode in ropes because intra-rope sliding of the constituent nanotubes occurs with ease. Our simulations indicate that the formation of these aggregates can be attributed to the mesoscopic mechanics of entangled nanotubes and to the sliding at the contacts. Starting from the single-walled carbon nanotubes, the sizes of the rings and rackets' heads increase with the rope diameter, indicating that the stability of the experimental aggregates can be largely explained by the competition between bending and van der Waals adhesion energies. Our results and simulation method should be useful for understanding nanoscale fibers in general.

  9. Effect of cobalt on microstructural parameters and mechanical properties of Ni-base single crystal superalloys

    International Nuclear Information System (INIS)

    Suzuki, Takanobu; Imai, Hachiro; Yokokawa, Tadaharu; Kobayashi, Toshiharu; Koizumi, Yutaka; Harada, Hiroshi

    2007-01-01

    The alloying effect of Cobalt (Co) to microstructural parameters and mechanical properties, such as partitioning ratios of alloying elements and creep strength, of Re-bearing Ni-base single crystal superalloys have been investigated. The second generation single crystal superalloys, TMS-82+, Ni-7.8Co-4.9Cr-1.9Mo-8.7W-5.3Al-6.0Ta-2.4Re-0.1Hf, in mass% (8Co) was compared to a Co-free (0Co) and 15 mass% Co (15Co) alloy which had the same chemical composition as TMS-82+ except that Co was changed. It was shown that the partitioning ratios of alloying elements trend to k(=X γ /X' γ )=1, as the content of Co was increased. Furthermore, it was found that there was suitable content of Co for the creep strength under various temperature-stress conditions. (author)

  10. Investigation on crystalline perfection, mechanical, piezoelectric and ferroelectric properties of L-tartaric acid single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Murugan, G. Senthil, E-mail: nanosen@gmail.com; Ramasamy, P., E-mail: nanosen@gmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam, Tamilnadu - 603110 (India)

    2014-04-24

    Polar organic nonlinear optical material, L-tartaric acid single crystals have been grown from slow evaporation solution growth technique. Single crystal X-ray diffraction study indicates that the grown crystal crystallized in monoclinic system with space group P2{sub 1}. Crystalline perfection of the crystal has been evaluated by high resolution X-ray diffraction technique and it reveals that the crystal quality is good and free from structural grain boundaries. Mechanical stability of the crystal has been analyzed by Vickers microhardness measurement and it exhibits reverse indentation size effect. Piezoelectric d{sub 33} co-efficient for the crystal has been examined and its value is 47 pC/N. The ferroelectric behaviour of the crystal was analyzed by polarization-electric field hysteresis loop measurement.

  11. Design and Development of a Solar Thermal Collector with Single Axis Solar Tracking Mechanism

    OpenAIRE

    Theebhan Mogana; Long Chua Yaw; Tiong Tay Tee

    2016-01-01

    The solar energy is a source of energy that is abundant in Malaysia and can be easily harvested. However, because of the rotation of the Earth about its axis, it is impossible to harvest the solar energy to the maximum capacity if the solar thermal collector is placed fix to a certain angle. In this research, a solar thermal dish with single axis solar tracking mechanism that will rotate the dish according to the position of the sun in the sky is designed and developed, so that more solar ray...

  12. Mechanical behavior study of single cell contraction by digital image correlation technique

    Science.gov (United States)

    Huang, Jianyong; Wu, Jia; Qin, Lei; Zhu, Tao; Xiong, Chunyang; Zhang, Youyi; Fang, Jing

    2008-11-01

    Precise determination of cellular traction forces has important significance in assessing cellular mechanical characteristic on micro/nano scale. Elastic substrate method is a useful way to study cellular traction forces, in which the cells are cultured on elastic gel substrate marked by randomly embedding fluorescent microbeads and they exert mechanical forces on the film to cause deformation of the substrate material. In this paper, we investigate the acquisition of deformation field induced by single cardiac myocyte by using digital image correlation (DIC) technique. In view of the fact that cellular force restoration is essentially an ill-posed inverse problem, which implies that the force reconstruction is susceptible to the input displacement noise, we develop a novel optimal filtering scheme in two-dimensional Fourier space to restrain displacement noise amplification. Experiments of traction force recovery for a real cardiac myocyte indicate the optimal scheme in combination with the DIC method enables us to reconstruct cellular traction fields with high accuracy.

  13. Transcending the biomarker mindset: deciphering disease mechanisms at the single cell level.

    Science.gov (United States)

    Danna, Erika A; Nolan, Garry P

    2006-02-01

    The application of proteomics to disease research promises to enhance the understanding and treatment of many human maladies through the identification of molecular profiles associated with each disease. However, although much is made of the utility of molecular signatures as markers of disease state, insufficient emphasis is often placed on the simultaneous need for biological mechanism inquiry. Focused and detailed analyses of disease-associated signaling networks have the potential to be more mechanistically informative than large-scale proteomic profiling approaches, providing insight into the cellular processes involved in pathogenesis, disease progression and therapeutic resistance; while still providing diagnostic or clinical management direction. Phospho-specific flow cytometry provides a method for the analysis of pathological signaling networks, enabling the investigation of disease mechanisms at the single-cell level.

  14. Molecular scale buckling mechanics in individual aligned single-wall carbon nanotubes on elastomeric substrates.

    Science.gov (United States)

    Khang, Dahl-Young; Xiao, Jianliang; Kocabas, Coskun; MacLaren, Scott; Banks, Tony; Jiang, Hanqing; Huang, Yonggang Y; Rogers, John A

    2008-01-01

    We have studied the scaling of controlled nonlinear buckling processes in materials with dimensions in the molecular range (i.e., approximately 1 nm) through experimental and theoretical studies of buckling in individual single-wall carbon nanotubes on substrates of poly(dimethylsiloxane). The results show not only the ability to create and manipulate patterns of buckling at these molecular scales, but also, that analytical continuum mechanics theory can explain, quantitatively, all measurable aspects of this system. Inverse calculation applied to measurements of diameter-dependent buckling wavelengths yields accurate values of the Young's moduli of individual SWNTs. As an example of the value of this system beyond its use in this type of molecular scale metrology, we implement parallel arrays of buckled SWNTs as a class of mechanically stretchable conductor.

  15. Influence of cobalt, tantalum, and tungsten on the microstructure and mechanical properties of superalloy single crystals

    International Nuclear Information System (INIS)

    Nathal, M.V.; Ebert, L.J.

    1982-01-01

    The influence of Co, Ta, and W on the microstructure and mechanical properties of nickel base super-alloy single crystals was investigated. A matrix of alloys was based on Mar-M 247 stripped of C, B, Zr, and Hf. The microstructures of the alloys were examined using optical and electron microscopy, phase extraction, X-ray diffraction, and differential thermal analysis. Tensile and creep-rupture tests were performed at 1000 C. An increase in tensile and creep strength resulted when Co was removed from alloys containing high refractory metal contents, but Co effects were negligible for alloys with lower refractory metal levels. In the composition range studied, W was more effective than Ta in increasing the creep resistance. The mechanical properties are discussed in relation to the microstructures of the alloys

  16. Influence of cobalt, tantalum, and tungsten on the microstructure and mechanical properties of superalloy single crystals

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1982-01-01

    The influence of Co, Ta, and W on the microstructure and mechanical properties of nickel base super-alloy single crystals was investigated. A matrix of alloys was based on Mar-M 247 stripped of C, B, Zr, and Hf. The microstructures of the alloys were examined using optical and electron microscopy, phase extraction, X-ray diffraction, and differential thermal analysis. Tensile and creep-rupture tests were performed at 1000 C. An increase in tensile and creep strength resulted when Co was removed from alloys containing high refractory metal contents, but Co effects were negligible for alloys with lower refractory metal levels. In the composition range studied, W was more effective than Ta in increasing the creep resistance. The mechanical properties are discussed in relation to the microstructures of the alloys.

  17. Experimental studies of the dynamic mechanical response of a single polymer chain

    DEFF Research Database (Denmark)

    Thormann, Esben; Evans, Drew R.; Craig, Vincent S. J.

    2006-01-01

    The high-frequency and low-amplitude dynamic mechanical response from a single poly(vinyl alcohol) chain was investigated. Modification of a commercial atomic force microscope enabled high-frequency and low-amplitude periodic deformations of polymer chains during extension to be performed...... mechanical response from poly(vinyl alcohol) does not differ from its static response. This result is not unexpected as poly(vinyl alcohol) is a highly flexible polymer with intramolecular relaxation processes taking place on a short time scale. The choice of a polymer with a fast relaxation allows its...... static properties to be recovered from the dynamic measurements and enables the method suggested in this paper for decoupling the polymer response from the hydrodynamic response to be validated....

  18. Mechanics governs single-cell signaling and multi-cell robustness in biofilm infections

    Science.gov (United States)

    Gordon, Vernita

    In biofilms, bacteria and other microbes are embedded in extracellular polymers (EPS). Multiple types of EPS can be produced by a single bacterial strain - the reasons for this redundancy are not well-understood. Our work suggests that different polymers may confer distinct mechanical benefits. Our model organism is Pseudomonas aeruginosa, an opportunistic human pathogen that forms chronic biofilm infections associated with increased antibiotic resistance and evasion of the immune defense. Biofilms initiate when bacteria attach to a surface, sense the surface, and change their gene expression. Changes in gene expression are regulated by a chemical signal, cyclic-di-GMP. We find that one EPS material, called ``PEL,'' enhances surface sensing by increasing mechanical coupling of single bacteria to the surface. Measurements of bacterial motility suggest that PEL may increase frictional interactions between the surface and the bacteria. Consistent with this, we show that bacteria increase cyclic-di-GMP signaling in response to mechanical shear stress. Mechanosensing has long been known to be important to the function of cells in higher eukaryotes, but this is one of only a handful of studies showing that bacteria can sense and respond to mechanical forces. For the mature biofilm, the embedding polymer matrix can protect bacteria both chemically and mechanically. P. aeruginosa infections in the cystic fibrosis (CF) lung often last for decades, ample time for the infecting strain(s) to evolve. Production of another EPS material, alginate, is well-known to tend to increase over time in CF infections. Alginate chemically protects biofilms, but also makes them softer and weaker. Recently, it is being increasingly recognized that bacteria in chronic CF infections also evolve to increase PSL production. We use oscillatory bulk rheology to determine the unique contributions of EPS materials to biofilm mechanics. Unlike alginate, increased PSL stiffens biofilms. Increasing both

  19. Identification of two-step chemical mechanisms using small temperature oscillations and a single tagged species.

    Science.gov (United States)

    Closa, F; Gosse, C; Jullien, L; Lemarchand, A

    2015-05-07

    In order to identify two-step chemical mechanisms, we propose a method based on a small temperature modulation and on the analysis of the concentration oscillations of a single tagged species involved in the first step. The thermokinetic parameters of the first reaction step are first determined. Then, we build test functions that are constant only if the chemical system actually possesses some assumed two-step mechanism. Next, if the test functions plotted using experimental data are actually even, the mechanism is attributed and the obtained constant values provide the rate constants and enthalpy of reaction of the second step. The advantage of the protocol is to use the first step as a probe reaction to reveal the dynamics of the second step, which can hence be relieved of any tagging. The protocol is anticipated to apply to many mechanisms of biological relevance. As far as ligand binding is considered, our approach can address receptor conformational changes or dimerization as well as competition with or modulation by a second partner. The method can also be used to screen libraries of untagged compounds, relying on a tracer whose concentration can be spectroscopically monitored.

  20. 3D Thermal and Mechanical Analysis of a Single Event Burnout

    Science.gov (United States)

    Peretti, Gabriela; Demarco, Gustavo; Romero, Eduardo; Tais, Carlos

    2015-08-01

    This paper presents a study related to thermal and mechanical behavior of power DMOS transistors during a Single Event Burnout (SEB) process. We use a cylindrical heat generation region for emulating the thermal and mechanical phenomena related to the SEB. In this way, it is avoided the complexity of the mathematical treatment of the ion-device interaction. This work considers locating the heat generation region in positions that are more realistic than the ones used in previous work. For performing the study, we formulate and validate a new 3D model for the transistor that maintains the computational cost at reasonable level. The resulting mathematical models are solved by means of the Finite Element Method. The simulations results show that the failure dynamics is dominated by the mechanical stress in the metal layer. Additionally, the time to failure depends on the heat source position, for a given power and dimension of the generation region. The results suggest that 3D modeling should be considered for a detailed study of thermal and mechanical effects induced by SEBs.

  1. Twenty years' single-center experience with mechanical heart valves: a critical review of anticoagulation policy.

    Science.gov (United States)

    Van Nooten, Guido J; Caes, Frank; François, Katrien; Van Bellleghem, Yves; Bové, Thierry; Vandenplas, Guy; Taeymans, Yves

    2012-01-01

    Since January 1990, a variety of mechanical valves (St. Jude Medical, CarboMedics, ATS Medical) have been implanted routinely at the authors' institution. The study aim was to analyze, retrospectively, the 20-year clinical results of those mechanical valves, and to challenge the anticoagulation policy employed over the years. Between January 1990 and December 2008, a total of 2,108 mechanical valves was inserted into 1,887 consecutive patients (1,346 aortic, 725 mitral, 27 tricuspid, 10 pulmonary). The mean age of the patients was 63 +/- 13.2 years, and the majority (61%) were males. Preoperatively, 71% the patients were in NYHA class > or = III (average 3.01). The most frequent comorbidities included: atrial fibrillation (n = 594), coronary disease (n = 567) and diabetes (n = 398). The follow up (99% complete) totaled 13,721 patient-years (pt-yr), and ranged from 12 to 241 months (average 84 months). In-hospital mortality was 5.2% (n = 98, 14 valve-related). Of the 629 late deaths, the majority were cardiac (n = 276). Survival (Kaplan-Meier estimation) was significantly better for aortic valve patients compared to mitral or multiple valve replacement (Mantel-Cox, p valve thrombosis 0.31, thromboembolism 1.08, and bleeding 0.91. However, as repeated events occurred in several patients, the hazard function was not constant. Multivariate analysis (Cox regression model) showed age > 70 years (p or = III (p II as significant risk factors for thromboembolism, while long-acting coumadin and NYHA class > II were significant risk factors for bleeding. This 20-year experience demonstrated excellent clinical outcomes for patients with mechanical prostheses, with no valve structural failure and an acceptable incidence of adverse events. INR values between 2-2.5 for aortic valve patients, and 3-3.5 for mitral valve patients, yielded the fewest major adverse events.

  2. Hepatitis C Virus and Hepatocellular Carcinoma: Pathogenetic Mechanisms and Impact of Direct-Acting Antivirals.

    Science.gov (United States)

    Schietroma, Ivan; Scheri, Giuseppe Corano; Pinacchio, Claudia; Statzu, Maura; Petruzziello, Arnolfo; Vullo, Vincenzo

    2018-01-01

    Globally, between 64 and 103 million people are chronically infected with Hepatitis C virus (HCV), with more than 4.6 million people in the United States and is associated with more than 15.000 deaths annually. Chronic infection can result in cirrhosis and hepatocellular carcinoma. Epidemiological studies have indicated that persistent infection with hepatitis C virus (HCV) is a major risk for the development of hepatocellular carcinoma (HCC), mainly through chronic inflammation, cell deaths, and proliferation. Despite the new direct-acting antiviral drugs (DAA's) being able to clear the HCV, HCC recurrence rate in these patients is still observed. In this review we highlighted some aspects that could be involved in the onset of HCV-induced HCC such as immune system, viral factors and host genetics factors.Moreover, we focused on some of the last reports about the effects of DAA's on the HCV clearance and their potential implications in HCC recurrence.

  3. The Single Supervisory Mechanism: the Building Pillar of the European Banking Union

    Directory of Open Access Journals (Sweden)

    Luigi Chiarella

    2016-07-01

    Full Text Available One of the lessons learned from the 2008 financial crisis is that when a bank in Europe goes into trouble the ensuing effects can reach far beyond the immediate threat to its depositors and shareholders. In particular, the crisis has revealed the extent to which irresponsible behavior in the banking sector could undermine the foundations of the financial system and threaten the real economy, turning a banking crisis into a sovereign debt crisis as occurred in the eurozone in 2011. In response to this lesson, Member States first tried to address the systemic fragility of their banking systems through national policy tools, but countries that share a common currency and are more interdependent required more integrated responses. Therefore, at the euro area summit in June 2012, the European Council agreed to break the vicious circle between banks and sovereign debt and decided to create a banking union that would allow a centralized supervision for banks in the euro area through a newly established Single Supervisory Mechanism (SSM and a centralized resolution scheme. The SSM became operational in November 2014 and represents the building pillar of the banking union. The purpose of this paper is then to provide, after a brief description of the background (Par. 1, an analysis of the Single Supervisory Mechanism, illustrating its functioning (Par. 2, then focusing on the position and the powers of the ECB within it (Par. 3 and finally pointing out some remarks on the potential weaknesses of the new regime (Par. 4.

  4. Single and competitive adsorption of OMPs by carbon nanotubes - mechanism and fitting models

    Science.gov (United States)

    Kamińska, Gabriela; Dudziak, Mariusz; Bohdziewicz, Jolanta; Kudlek, Edyta

    2017-11-01

    The adsorption of three organic micropollutants (diclofenac - DFN, pentachlorophenol - PCP and octylphenol - OP) on two kinds of carbon nanotubes (single walled carbon nanotubes - SWCNT and single walled carbon nanotubes with amine group - SWCNT-NH2) was investigated, in single and bicomponent solution at pH 5. SWCNT-NH2 had three times lower specific surface area than SWCNT. Significant differences were observed in sorption capacity of SWCNT and SWCNT-NH2 for given chemicals. The sorption uptake changes in the following order: OP > PCP > DFN for SWCNT and DFN > PCP > OP for SWCNT-NH2. A few times higher adsorption of OP on SWCNT came from low OP solubility in water in comparison to PCP and DFN. While, higher adsorption of DFN and PCP on SWCNT-NH2 was a result of electrostatic attraction between dissociated form of these chemicals and positively charged SWCNT-NH2 at pH 5. In adsorption from bicomponent solution, significant competition was observed between PCP and DFN due to similar adsorption mechanism on SWCNT-NH2. Opposite tendency was observed for SWCNT, DFN did not greatly affect adsorption of PCP and OP since they were very easily absorbable by sigma-sigma interaction.

  5. Single and competitive adsorption of OMPs by carbon nanotubes – mechanism and fitting models

    Directory of Open Access Journals (Sweden)

    Kamińska Gabriela

    2017-01-01

    Full Text Available The adsorption of three organic micropollutants (diclofenac – DFN, pentachlorophenol – PCP and octylphenol – OP on two kinds of carbon nanotubes (single walled carbon nanotubes – SWCNT and single walled carbon nanotubes with amine group – SWCNT-NH2 was investigated, in single and bicomponent solution at pH 5. SWCNT-NH2 had three times lower specific surface area than SWCNT. Significant differences were observed in sorption capacity of SWCNT and SWCNT-NH2 for given chemicals. The sorption uptake changes in the following order: OP > PCP > DFN for SWCNT and DFN > PCP > OP for SWCNT-NH2. A few times higher adsorption of OP on SWCNT came from low OP solubility in water in comparison to PCP and DFN. While, higher adsorption of DFN and PCP on SWCNT-NH2 was a result of electrostatic attraction between dissociated form of these chemicals and positively charged SWCNT-NH2 at pH 5. In adsorption from bicomponent solution, significant competition was observed between PCP and DFN due to similar adsorption mechanism on SWCNT-NH2. Opposite tendency was observed for SWCNT, DFN did not greatly affect adsorption of PCP and OP since they were very easily absorbable by sigma-sigma interaction.

  6. Free vibration analysis of single-walled boron nitride nanotubes based on a computational mechanics framework

    Science.gov (United States)

    Yan, J. W.; Tong, L. H.; Xiang, Ping

    2017-12-01

    Free vibration behaviors of single-walled boron nitride nanotubes are investigated using a computational mechanics approach. Tersoff-Brenner potential is used to reflect atomic interaction between boron and nitrogen atoms. The higher-order Cauchy-Born rule is employed to establish the constitutive relationship for single-walled boron nitride nanotubes on the basis of higher-order gradient continuum theory. It bridges the gaps between the nanoscale lattice structures with a continuum body. A mesh-free modeling framework is constructed, using the moving Kriging interpolation which automatically satisfies the higher-order continuity, to implement numerical simulation in order to match the higher-order constitutive model. In comparison with conventional atomistic simulation methods, the established atomistic-continuum multi-scale approach possesses advantages in tackling atomic structures with high-accuracy and high-efficiency. Free vibration characteristics of single-walled boron nitride nanotubes with different boundary conditions, tube chiralities, lengths and radii are examined in case studies. In this research, it is pointed out that a critical radius exists for the evaluation of fundamental vibration frequencies of boron nitride nanotubes; opposite trends can be observed prior to and beyond the critical radius. Simulation results are presented and discussed.

  7. Modeling single molecule junction mechanics as a probe of interface bonding

    Science.gov (United States)

    Hybertsen, Mark S.

    2017-03-01

    Using the atomic force microscope based break junction approach, applicable to metal point contacts and single molecule junctions, measurements can be repeated thousands of times resulting in rich data sets characterizing the properties of an ensemble of nanoscale junction structures. This paper focuses on the relationship between the measured force extension characteristics including bond rupture and the properties of the interface bonds in the junction. A set of exemplary model junction structures has been analyzed using density functional theory based calculations to simulate the adiabatic potential surface that governs the junction elongation. The junction structures include representative molecules that bond to the electrodes through amine, methylsulfide, and pyridine links. The force extension characteristics are shown to be most effectively analyzed in a scaled form with maximum sustainable force and the distance between the force zero and force maximum as scale factors. Widely used, two parameter models for chemical bond potential energy versus bond length are found to be nearly identical in scaled form. Furthermore, they fit well to the present calculations of N-Au and S-Au donor-acceptor bonds, provided no other degrees of freedom are allowed to relax. Examination of the reduced problem of a single interface, but including relaxation of atoms proximal to the interface bond, shows that a single-bond potential form renormalized by an effective harmonic potential in series fits well to the calculated results. This allows relatively accurate extraction of the interface bond energy. Analysis of full junction models shows cooperative effects that go beyond the mechanical series inclusion of the second bond in the junction, the spectator bond that does not rupture. Calculations for a series of diaminoalkanes as a function of molecule length indicate that the most important cooperative effect is due to the interactions between the dipoles induced by the donor

  8. Hip-abductor fatigue and single-leg landing mechanics in women athletes.

    Science.gov (United States)

    Patrek, Mary F; Kernozek, Thomas W; Willson, John D; Wright, Glenn A; Doberstein, Scott T

    2011-01-01

    Reduced hip-abductor strength and muscle activation may be associated with altered lower extremity mechanics, which are thought to increase the risk for anterior cruciate ligament injury. However, experimental evidence supporting this relationship is limited. To examine the changes in single-leg landing mechanics and gluteus medius recruitment that occur after a hip-abductor fatigue protocol. Descriptive laboratory study. Twenty physically active women (age  =  21.0 ± 1.3 years). Participants were tested before (prefatigue) and after (postfatigue) a hip-abductor fatigue protocol consisting of repetitive side-lying hip abduction. Outcome measures included sagittal-plane and frontal-plane hip and knee kinematics at initial contact and at 60 milliseconds after initial contact during 5 single-leg landings from a height of 40 cm. Peak hip and knee sagittal-plane and frontal-plane joint moments during this time interval were also analyzed. Measures of gluteus medius activation, including latency, peak amplitude, and integrated signal, were recorded. A small (hip-abduction angle at initial contact and a small (hip at initial contact or at 60 milliseconds after initial contact. Peak external knee-adduction moment decreased 27% and peak hip adduction moment decreased 24% during the postfatigue landing condition. Gluteus medius activation was delayed after the protocol, but no difference in peak or integrated signal was seen during the landing trials. Changes observed during single-leg landings after hip-abductor fatigue were not generally considered unfavorable to the integrity of the anterior cruciate ligament. Further work may be justified to study the role of hip-abductor activation in protecting the knee during landing.

  9. Mobility-limiting mechanisms in single and dual channel strained Si/SiGe MOSFETs

    International Nuclear Information System (INIS)

    Olsen, S.H.; Dobrosz, P.; Escobedo-Cousin, E.; Bull, S.J.; O'Neill, A.G.

    2005-01-01

    Dual channel strained Si/SiGe CMOS architectures currently receive great attention due to maximum performance benefits being predicted for both n- and p-channel MOSFETs. Epitaxial growth of a compressively strained SiGe layer followed by tensile strained Si can create a high mobility buried hole channel and a high mobility surface electron channel on a single relaxed SiGe virtual substrate. However, dual channel n-MOSFETs fabricated using a high thermal budget exhibit compromised mobility enhancements compared with single channel devices, in which both electron and hole channels form in strained Si. This paper investigates the mobility-limiting mechanisms of dual channel structures. The first evidence of increased interface roughness due to the introduction of compressively strained SiGe below the tensile strained Si channel is presented. Interface corrugations degrade electron mobility in the strained Si. Roughness measurements have been carried out using AFM and TEM. Filtering AFM images allowed roughness at wavelengths pertinent to carrier transport to be studied and the results are in agreement with electrical data. Furthermore, the first comparison of strain measurements in the surface channels of single and dual channel architectures is presented. Raman spectroscopy has been used to study channel strain both before and after processing and indicates that there is no impact of the buried SiGe layer on surface macrostrain. The results provide further evidence that the improved performance of the single channel devices fabricated using a high thermal budget arises from improved surface roughness and reduced Ge diffusion into the Si channel

  10. Mechanical Revascularization for Acute Ischemic Stroke: A Single-Center, Retrospective Analysis

    International Nuclear Information System (INIS)

    Jeromel, Miran; Milosevic, Z. V.; Kocijancic, I. J.; Lovric, D.; Svigelj, V.; Zvan, B.

    2013-01-01

    BackgroundEndovascular mechanical revascularization (thrombectomy) is an increasingly used method for intracranial large vessel recanalization in acute stroke. The purpose of the study was to analyze the recanalization rate, clinical outcome, and complication rate in our stroke patients treated with mechanical revascularization. A total of 57 patients with large vessel stroke (within 3 h for anterior and 12 h for posterior circulation) were treated with mechanical revascularization at a single center during 24 months. The primary goal of endovascular treatment using different mechanical devices was recanalization of the occluded vessel. Recanalization rate (reported as thrombolysis in cerebral infarction [TICI] score), clinical outcome (reported as National Institutes of Health Stroke Scale [NIHSS] score and modified Rankin scale [mRS] score), as well as periprocedural complications were analyzed. The mean age of the patients was 63.1 ± 12.9 years, with baseline median NIHSS score of 14 (interquartile range, 9.5–19). Successful recanalization (TICI 2b or 3) was achieved in 41 (72 %) patients. Twenty patients (35 %) presented with favorable outcome (mRS ≤2) 30 days after stroke. Overall, significant neurological improvement (≥4 NIHSS point reduction) occurred in 36 (63 %) patients. A clinically significant procedure-related adverse events (vessel disruption, peri/postprocedural intracranial bleeding) defined with decline in NIHSS of ≥4 or death occurred in three (5 %) patients. The study showed a high recanalization rate with improved clinical outcome and a low rate of periprocedural complications in our stroke patients treated with mechanical revascularization. Therefore, we could conclude that endovascular revascularization (primary or in combination with a bridging thrombolysis) was an effective and safe procedure for intracranial large vessel recanalization in acute stroke.

  11. 76 FR 66950 - Privacy Act; Notice of Revision of System of Records, the Single Family Housing Enterprise Data...

    Science.gov (United States)

    2011-10-28

    ... Revision of System of Records, the Single Family Housing Enterprise Data Warehouse AGENCY: Office of the... systems, the Single Family Housing Enterprise Data Warehouse (SFHEDW). The revision to the record system...: Single Family Housing Enterprise Data Warehouse (SFHEDW). System location: The HUD Data Center, Hewlett...

  12. TRANSPARENT TESTA 16 and 15 act through different mechanisms to control proanthocyanidin accumulation in Arabidopsis testa.

    Science.gov (United States)

    Xu, W; Bobet, S; Le Gourrierec, J; Grain, D; De Vos, D; Berger, A; Salsac, F; Kelemen, Z; Boucherez, J; Rolland, A; Mouille, G; Routaboul, J M; Lepiniec, L; Dubos, C

    2017-05-17

    Flavonoids are secondary metabolites that fulfil a multitude of functions during the plant life cycle. In Arabidopsis proanthocyanidins (PAs) are flavonoids that specifically accumulate in the innermost integuments of the seed testa (i.e. endothelium), as well as in the chalaza and micropyle areas, and play a vital role in protecting the embryo against various biotic and abiotic stresses. PAs accumulation in the endothelium requires the activity of the MADS box transcription factor TRANSPARENT TESTA (TT) 16 (ARABIDOPSIS B-SISTER/AGAMOUS-LIKE 32) and the UDP-glycosyltransferase TT15 (UGT80B1). Interestingly tt16 and tt15 mutants display a very similar flavonoid profiles and patterns of PA accumulation. By using a combination of genetic, molecular, biochemical, and histochemical methods, we showed that both TT16 and TT15 act upstream the PA biosynthetic pathway, but through two distinct genetic routes. We also demonstrated that the activity of TT16 in regulating cell fate determination and PA accumulation in the endothelium is required in the chalaza prior to the globular stage of embryo development. Finally this study provides new insight showing that TT16 and TT15 functions extend beyond PA biosynthesis in the inner integuments of the Arabidopsis seed coat. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  13. Field electron emission characteristics and physical mechanism of individual single-layer graphene.

    Science.gov (United States)

    Xiao, Zhiming; She, Juncong; Deng, Shaozhi; Tang, Zikang; Li, Zhibing; Lu, Jianming; Xu, Ningsheng

    2010-11-23

    Due to its difficulty, experimental measurement of field emission from a single-layer graphene has not been reported, although field emission from a two-dimensional (2D) regime has been an attractive topic. The open surface and sharp edge of graphene are beneficial for field electron emission. A 2D geometrical effect, such as massless Dirac fermion, can lead to new mechanisms in field emission. Here, we report our findings from in situ field electron emission characterization on an individual singe-layer graphene and the understanding of the related mechanism. The measurement of field emission from the edges was done using a microanode probe equipped in a scanning electron microscope. We show that repeatable stable field emission current can be obtained after a careful conditioning process. This enables us to examine experimentally the typical features of the field emission from a 2D regime. We plot current versus applied field data, respectively, in ln(I/E(3/2)) ∼ 1/E and ln(I/E(3)) ∼ 1/E(2) coordinates, which have recently been proposed for field emission from graphene in high- and low-field regimes. It is observed that the plots all exhibit an upward bending feature, revealing that the field emission processes undergo from a low- to high-field transition. We discuss with theoretical analysis the physical mechanism responsible for the new phenomena.

  14. A robust single-beam optical trap for a gram-scale mechanical oscillator.

    Science.gov (United States)

    Altin, P A; Nguyen, T T-H; Slagmolen, B J J; Ward, R L; Shaddock, D A; McClelland, D E

    2017-11-06

    Precise optical control of microscopic particles has been mastered over the past three decades, with atoms, molecules and nano-particles now routinely trapped and cooled with extraordinary precision, enabling rapid progress in the study of quantum phenomena. Achieving the same level of control over macroscopic objects is expected to bring further advances in precision measurement, quantum information processing and fundamental tests of quantum mechanics. However, cavity optomechanical systems dominated by radiation pressure - so-called 'optical springs' - are inherently unstable due to the delayed dynamical response of the cavity. Here we demonstrate a fully stable, single-beam optical trap for a gram-scale mechanical oscillator. The interaction of radiation pressure with thermo-optic feedback generates damping that exceeds the mechanical loss by four orders of magnitude. The stability of the resultant spring is robust to changes in laser power and detuning, and allows purely passive self-locking of the cavity. Our results open up a new way of trapping and cooling macroscopic objects for optomechanical experiments.

  15. Dynamic mechanical analysis of single walled carbon nanotubes/polymethyl methacrylate nanocomposite films

    International Nuclear Information System (INIS)

    Badawi, Ali; Al Hosiny, N.

    2015-01-01

    Dynamic mechanical properties of nanocomposite films with different ratios of single walled carbon nanotubes/polymethyl methacrylate (SWCNTs/PMMA) are studied. Nanocomposite films of different ratios (0, 0.5, 1.0, and 2.0 weight percent (wt%)) of SWCNTs/PMMA are fabricated by using a casting technique. The morphological and structural properties of both SWCNT powder and SWCNTs/PMMA nanocomposite films are investigated by using a high resolution transmission electron microscope and x-ray diffractometer respectively. The mechanical properties including the storage modulus, loss modulus, loss factor (tan δ) and stiffness of the nanocomposite film as a function of temperature are recorded by using a dynamic mechanical analyzer at a frequency of 1 Hz. Compared with pure PMMA film, the nanocomposite films with different ratios of SWCNTs/PMMA are observed to have enhanced storage moduli, loss moduli and high stiffness, each of which is a function of temperature. The intensity of the tan δ peak for pure PMMA film is larger than those of the nanocomposite films. The glass transition temperature (T g ) of SWCNTs/PMMA nanocomposite film shifts towards the higher temperature side with respect to pure PMMA film from 91.2 °C to 99.5 °C as the ratio of SWCNTs/PMMA increases from 0 to 2.0 wt%. (paper)

  16. MEMS measurements of single cell stiffness decay due to cyclic mechanical loading.

    Science.gov (United States)

    Barazani, Bruno; Warnat, Stephan; MacIntosh, Andrew J; Hubbard, Ted

    2017-08-25

    The goal of this study was to measure the mechanical stiffness of individual cells and to observe changes due to the application of repeated cell mechanical loads. 28 single baker's yeast cells (Saccharomyces cerevisiae) were fatigue tested and had their stiffness measured during repetitive loading cycles performed by a MEMS squeezer in aqueous media. Electrothermal micro-actuators compressed individual cells against a reference back spring; cell and spring motions were measured using a FFT image analysis technique with ~10 nm resolution. Cell stiffness was calculated based on measurements of cell elongation vs. applied force which resulted in stiffness values in the 2-10 N/m range. The effect of increased force was studied for cells mechanically cycled 37 times. Cell stiffness decreased as the force and the cycle number increased. After 37 loading cycles (~4 min), forces of 0.24, 0.29, 0.31, and 0.33 μN caused stiffness drops of 5%, 13%, 31% and 41% respectively. Cells force was then set to 0.29 μN and cells were tested over longer runs of 118 and 268 cycles. After 118 cycles (~12 min) cells experienced an average stiffness drop of 68%. After 268 cycles (~25 min) cells had a stiffness drop of 77%, and appeared to reach a stiffness plateau of 20-25% of the initial stiffness after approximately 200 cycles.

  17. Computational exploration of single-protein mechanics by steered molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sotomayor, Marcos [Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio (United States)

    2015-12-31

    Hair cell mechanotransduction happens in tens of microseconds, involves forces of a few picoNewtons, and is mediated by nanometer-scale molecular conformational changes. As proteins involved in this process become identified and their high resolution structures become available, multiple tools are being used to explore their “single-molecule responses” to force. Optical tweezers and atomic force microscopy offer exquisite force and extension resolution, but cannot reach the high loading rates expected for high frequency auditory stimuli. Molecular dynamics (MD) simulations can reach these fast time scales, and also provide a unique view of the molecular events underlying protein mechanics, but its predictions must be experimentally verified. Thus a combination of simulations and experiments might be appropriate to study the molecular mechanics of hearing. Here I review the basics of MD simulations and the different methods used to apply force and study protein mechanics in silico. Simulations of tip link proteins are used to illustrate the advantages and limitations of this method.

  18. PolyMUMPs MEMS device to measure mechanical stiffness of single cells in aqueous media

    Science.gov (United States)

    Warnat, S.; King, H.; Forbrigger, C.; Hubbard, T.

    2015-02-01

    A method of experimentally determining the mechanical stiffness of single cells by using differential displacement measurements in a two stage spring system is presented. The spring system consists of a known MEMS reference spring and an unknown cellular stiffness: the ratio of displacements is related to the ratio of stiffness. A polyMUMPs implementation for aqueous media is presented and displacement measurements made from optical microphotographs using a FFT based displacement method with a repeatability of ~20 nm. The approach was first validated on a MEMS two stage spring system of known stiffness. The measured stiffness ratios of control structures (i) MEMS spring systems and (ii) polystyrene microspheres were found to agree with theoretical values. Mechanical tests were then performed on Saccharomyces cerevisiae (Baker’s yeast) in aqueous media. Cells were placed (using a micropipette) inside MEMS measuring structures and compressed between two jaws using an electrostatic actuator and displacements measured. Tested cells showed stiffness values between 5.4 and 8.4 N m-1 with an uncertainty of 11%. In addition, non-viable cells were tested by exposing viable cells to methanol. The resultant mean cell stiffness dropped by factor of 3 × and an explicit discrimination between viable and non-viable cells based on mechanical stiffness was seen.

  19. Simultaneous single-molecule measurements of phage T7 replisome composition and function reveal the mechanism of polymerase exchange

    NARCIS (Netherlands)

    Loparo, Joseph J.; Kulczyk, Arkadiusz W.; Richardson, Charles C.; Oijen, Antoine M. van

    2011-01-01

    A complete understanding of the molecular mechanisms underlying the functioning of large, multiprotein complexes requires experimental tools capable of simultaneously visualizing molecular architecture and enzymatic activity in real time. We developed a novel single-molecule assay that combines the

  20. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures

    OpenAIRE

    Shim, Hye Won; Yang, Byoung-Eun

    2015-01-01

    PURPOSE To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos? implants. MATERIALS AND METHODS This was a retrospective clinical study that analyzed 450 single Ankylos? implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to ag...

  1. Gene expression suggests double-segmental and single-segmental patterning mechanisms during posterior segment addition in the beetle Tribolium castaneum.

    Science.gov (United States)

    Janssen, Ralf

    2014-01-01

    In the model arthropod Drosophila, all segments are patterned simultaneously in the blastoderm. In most other arthropods, however, posterior segments are added sequentially from a posterior segment addition zone. Posterior addition of single segments likely represents the ancestral mode of arthropod segmentation, although in Drosophila, segments are patterned in pairs by the pair-rule genes. It has been shown that in the new model insect, the beetle Tribolium, a segmentation clock operates that apparently patterns all segments in pairs as well. Here, I report on the expression of the segment polarity gene H15/midline in Tribolium. In the anterior embryo, segmental stripes of H15 appear in pairs, but in the posterior of the embryo stripes appear in a single-segmental periodicity. This implies that either two completely different segmentation-mechanisms may act in the germ band of Tribolium, that the segmentation clock changes its periodicity during development, or that the speed in which posterior segments are patterned changes. In any case, the data suggest the presence of another (or modified), yet undiscovered, mechanism of posterior segment addition in one of the best-understood arthropod models. The finding of a hitherto unrecognized segmentation mechanism in Tribolium may have major implications for the understanding of the origin of segmentation mechanisms, including the origin of pair rule patterning. It also calls for (re)-investigation of posterior segment addition in Tribolium and other previously studied arthropod models.

  2. Structural, spectral and mechanical studies of bimetallic crystal: cadmium manganese thiocyanate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, M.; Vijaya Prasath, G.; Mahalingam, T.; Ravi, G. [Alagappa University, Department of Physics, Karaikudi (India); Bhagavannarayan, G.; Vijayan, N. [National Physical Laboratory, Materials Characterization Division, New Delhi (India)

    2012-09-15

    A nonlinear optical bimetallic thiocyanate complex crystal, cadmium manganese thiocyanate (CMTC) has been successfully synthesized. The growth of single crystals of cadmium manganese thiocyanate has been accomplished from aqueous solution using slow evaporation method. The presence of manganese and cadmium in the synthesized material was confirmed through energy dispersive spectrum (EDS) analysis. Structural analysis was carried out using powder X-ray diffractometer (PXRD) and crystalline perfection of the grown crystals was ascertained by high-resolution X-ray diffraction (HRXRD) analysis. Fourier transform infrared (FTIR) spectrum was taken to confirm the functional groups. The transmittance spectrum of the crystal in the UV-visible region has been recorded and the cutoff wavelength has been determined. The dielectric measurements for the crystals were performed for various frequencies and temperatures. The mechanical properties were evaluated by Vickers microhardness testing, which reveals hardness and stiffness constant of the crystals. (orig.)

  3. Design and Development of a Solar Thermal Collector with Single Axis Solar Tracking Mechanism

    Directory of Open Access Journals (Sweden)

    Theebhan Mogana

    2016-01-01

    Full Text Available The solar energy is a source of energy that is abundant in Malaysia and can be easily harvested. However, because of the rotation of the Earth about its axis, it is impossible to harvest the solar energy to the maximum capacity if the solar thermal collector is placed fix to a certain angle. In this research, a solar thermal dish with single axis solar tracking mechanism that will rotate the dish according to the position of the sun in the sky is designed and developed, so that more solar rays can be reflected to a focal point and solar thermal energy can be harvested from the focal point. Data were collected for different weather conditions and performance of the solar thermal collector with a solar tracker were studied and compared with stationary solar thermal collector.

  4. A Single Polyaniline Nanofiber Field Effect Transistor and Its Gas Sensing Mechanisms

    Science.gov (United States)

    Chen, Dajing; Lei, Sheng; Chen, Yuquan

    2011-01-01

    A single polyaniline nanofiber field effect transistor (FET) gas sensor fabricated by means of electrospinning was investigated to understand its sensing mechanisms and optimize its performance. We studied the morphology, field effect characteristics and gas sensitivity of conductive nanofibers. The fibers showed Schottky and Ohmic contacts based on different electrode materials. Higher applied gate voltage contributes to an increase in gas sensitivity. The nanofiber transistor showed a 7% reversible resistance change to 1 ppm NH3 with 10 V gate voltage. The FET characteristics of the sensor when exposed to different gas concentrations indicate that adsorption of NH3 molecules reduces the carrier mobility in the polyaniline nanofiber. As such, nanofiber-based sensors could be promising for environmental and industrial applications. PMID:22163969

  5. Failure of single electron descriptions of molecular orbital collision processes. [Electron promotion mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Elston, S.B.

    1978-01-01

    Inner-shell excitation occurring in low and moderate (keV range) energy collisions between light atomic and ionic systems is frequently describable in terms of molecular promotion mechanisms, which were extensively explored both theoretically and experimentally. The bulk of such studies have concentrated on processes understandable through the use of single- and independent-electron models. Nonetheless, it is possible to find cases of inner-shell excitation in relatively simple collision systems which involve nearly simultaneous multiple-electron transitions and transitions induced by inherently two-electron interactions. Evidence for these many- and nonindependent-electron phenomena in inner-shell excitation processes and the importance of considering such effects in the interpretation of collisionally induced excitation spectra is discussed. 13 references.

  6. Do environmental changes or juvenile competition act as mechanisms of species displacement in crayfishes?

    Science.gov (United States)

    Westhoff, Jacob T.; DiStefano, R.J.; Magoulick, D.D.

    2012-01-01

    The Big Creek Crayfish, Orconectes peruncus, is native to the St. Francis River drainage in Missouri, USA and is often absent where the introduced Woodland Crayfish, Orconectes hylas, has established. We performed a field experiment to determine whether effects of current abiotic conditions and interspecific competition with O. hylas were responsible for displacement of O. peruncus from parts of their former range. We examined growth and survival of juvenile male O. peruncus exposed to juvenile male O. hylas in enclosures at two sites in the former range of O. peruncus. Enclosures contained 8 (low density) or 16 individuals (high density) and had O. peruncus only (control) or both species (interspecific treatment). Juvenile O. peruncus were able to survive and grow in portions of their former range, implicating biotic versus abiotic factors in the displacement of O. peruncus. Survival rates of O. peruncus did not differ among treatments at either site. Orconectes peruncus showed significant growth in all treatments and interspecific effects were not greater than intraspecific effects on O. peruncus growth rates. High-density treatments showed significantly reduced O. peruncus growth rates compared to low-density treatments, except in Carver Creek interspecific treatments. When considered in the context of previous studies examining the effects of O. hylas on O. peruncus, results suggest that neither direct competition between juvenile males of the two species or abiotic change are responsible for the decreased range of O. peruncus. Additional research is required to determine the mechanism(s) driving the displacement of O. peruncus. ?? 2011 Springer Science+Business Media B.V.

  7. Mechanical confinement for tuning ferroelectric response in PMN-PT single crystal

    Science.gov (United States)

    Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

    2015-02-01

    Ferroelectrics form an important class of materials and are employed for a variety of applications. However, specific applications dictate the need of tailored ferroelectric response. This creates a requirement to obtain ferroelectric materials with tunable properties. Generally, chemical modifications or domain engineering are employed to this effect. This study attempts to shed light on the use of compressive pre-stresses for tuning and enhancing the ferroelectric properties. For the purpose, polarization versus electric field hysteresis data for 68Pb(Mn1/3Nb2/3)O3-32PbTiO3 (PMN-PT) single crystals were obtained as a function of uniaxial compressive stresses and operating temperatures. These data were utilized to investigate the effects of mechanical confinement for four individual case studies of electrocaloric effect, electrical energy storage, pyroelectric, and piezoelectric effect. A significant improvement was obtained for all case studies. The adiabatic temperature change was improved by ≈80% (28 MPa, 353 K); energy storage density increased by a factor of five (28 MPa, 353 K); pyroelectric figure of merits improved by an order of magnitude (21 MPa) and the piezoelectric coefficient was tailored (variable stress). The results offer promising insight into the use of directional confinement for improving application specific ferroelectric properties in PMN-PT single crystal.

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

    Science.gov (United States)

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

    2016-05-01

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

  9. Role of solvent environments in single molecule conductance used insulator-modified mechanically controlled break junctions

    Science.gov (United States)

    Muthusubramanian, Nandini; Maity, Chandan; Galan Garcia, Elena; Eelkema, Rienk; Grozema, Ferdinand; van der Zant, Herre; Kavli Institute of Nanoscience Collaboration; Department of Chemical Engineering Collaboration

    We present a method for studying the effects of polar solvents on charge transport through organic/biological single molecules by developing solvent-compatible mechanically controlled break junctions of gold coated with a thin layer of aluminium oxide using plasma enhanced atomic layer deposition (ALD). The optimal oxide thickness was experimentally determined to be 15 nm deposited at ALD operating temperature of 300°C which yielded atomically sharp electrodes and reproducible single-barrier tunnelling behaviour across a wide conductance range between 1 G0 and 10-7 G0. The insulator protected MCBJ devices were found to be effective in various solvents such as deionized water, phosphate buffered saline, methanol, acetonitrile and dichlorobenzene. The yield of molecular junctions using such insulated electrodes was tested by developing a chemical protocol for synthesizing an amphipathic form of oligo-phenylene ethynylene (OPE3-PEO) with thioacetate anchoring groups. This work has further applications in studying effects of solvation, dipole orientation and other thermodynamic interactions on charge transport. Eu Marie Curie Initial Training Network (ITN). MOLECULAR-SCALE ELECTRONICS: ``MOLESCO'' Project Number 606728.

  10. Mechanisms of temporal variation in single-nephron blood flow in rats

    DEFF Research Database (Denmark)

    Yip, K P; Holstein-Rathlou, N H; Marsh, D J

    1993-01-01

    Modified laser-Doppler velocimetry was used to determine the number of different mechanisms regulating single-nephron blood flow. Two oscillations were identified in star vessel blood flow, one at 20-50 mHz and another at 100-200 mHz. Tubuloglomerular feedback (TGF) mediates the slower oscillation......, and the faster one is probably myogenic in origin. Acute hypertension increased autospectral power in the 20-50 mHz and 100-200 mHz frequency bands to 282 +/- 50 and 248 +/- 64%, respectively, of control even though mean single-nephron blood flow was autoregulated. Mean blood flow increased 24.6 +/- 6.1% when...... TGF was inhibited by intratubular perfusion with furosemide, and it decreased 42.8 +/- 3.9% when TGF was saturated by tubular perfusion with artificial tubular fluid at high rates. Autospectral power in the low-frequency band decreased 50.5 +/- 9.6% during furosemide and decreased 74.9 +/- 5.9% during...

  11. Experimental results of single screw mechanical tests: a follow-up to SAND2005-6036.

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sandwook; Lee, Kenneth L.; Korellis, John S.; McFadden, Sam X.

    2006-08-01

    The work reported here was conducted to address issues raised regarding mechanical testing of attachment screws described in SAND2005-6036, as well as to increase the understanding of screw behavior through additional testing. Efforts were made to evaluate fixture modifications and address issues of interest, including: fabrication of 45{sup o} test fixtures, measurement of the frictional load from the angled fixture guide, employment of electromechanical displacement transducers, development of a single-shear test, and study the affect of thread start orientation on single-shear behavior. A286 and 302HQ, No.10-32 socket-head cap screws were tested having orientations with respect to the primary loading axis of 0{sup 0}, 45{sup o}, 60{sup o}, 75{sup o} and 90{sup o} at stroke speeds 0,001 and 10 in/sec. The frictional load resulting from the angled screw fixture guide was insignificant. Load-displacement curves of A286 screws did not show a minimum value in displacement to failure (DTF) for 60{sup o} shear tests. Tests of 302HQ screws did not produce a consistent trend in DTF with load angle. The effect of displacement rate on DTF became larger as shear angle increased for both A286 and 302HQ screws.

  12. The nesprin-cytoskeleton interface probed directly on single nuclei is a mechanically rich system.

    Science.gov (United States)

    Balikov, Daniel A; Brady, Sonia K; Ko, Ung Hyun; Shin, Jennifer H; de Pereda, Jose M; Sonnenberg, Arnoud; Sung, Hak-Joon; Lang, Matthew J

    2017-09-03

    The cytoskeleton provides structure and plays an important role in cellular function such as migration, resisting compression forces, and transport. The cytoskeleton also reacts to physical cues such as fluid shear stress or extracellular matrix remodeling by reorganizing filament associations, most commonly focal adhesions and cell-cell cadherin junctions. These mechanical stimuli can result in genome-level changes, and the physical connection of the cytoskeleton to the nucleus provides an optimal conduit for signal transduction by interfacing with nuclear envelope proteins, called nesprins, within the LINC (linker of the nucleus to the cytoskeleton) complex. Using single-molecule on single nuclei assays, we report that the interactions between the nucleus and the cytoskeleton, thought to be nesprin-cytoskeleton interactions, are highly sensitive to force magnitude and direction depending on whether cells are historically interfaced with the matrix or with cell aggregates. Application of ∼10-30 pN forces to these nesprin linkages yielded structural transitions, with a base transition size of 5-6 nm, which are speculated to be associated with partial unfoldings of the spectrin domains of the nesprins and/or structural changes of histones within the nucleus.

  13. Extension of lifespan in C. elegans by naphthoquinones that act through stress hormesis mechanisms.

    Directory of Open Access Journals (Sweden)

    Piper R Hunt

    Full Text Available Hormesis occurs when a low level stress elicits adaptive beneficial responses that protect against subsequent exposure to severe stress. Recent findings suggest that mild oxidative and thermal stress can extend lifespan by hormetic mechanisms. Here we show that the botanical pesticide plumbagin, while toxic to C. elegans nematodes at high doses, extends lifespan at low doses. Because plumbagin is a naphthoquinone that can generate free radicals in vivo, we investigated whether it extends lifespan by activating an adaptive cellular stress response pathway. The C. elegans cap'n'collar (CNC transcription factor, SKN-1, mediates protective responses to oxidative stress. Genetic analysis showed that skn-1 activity is required for lifespan extension by low-dose plumbagin in C. elegans. Further screening of a series of plumbagin analogs identified three additional naphthoquinones that could induce SKN-1 targets in C. elegans. Naphthazarin showed skn-1dependent lifespan extension, over an extended dose range compared to plumbagin, while the other naphthoquinones, oxoline and menadione, had differing effects on C. elegans survival and failed to activate ARE reporter expression in cultured mammalian cells. Our findings reveal the potential for low doses of naturally occurring naphthoquinones to extend lifespan by engaging a specific adaptive cellular stress response pathway.

  14. Extracellular DNA Release Acts as an Antifungal Resistance Mechanism in Mature Aspergillus fumigatus Biofilms

    Science.gov (United States)

    Rajendran, Ranjith; Williams, Craig; Lappin, David F.; Millington, Owain; Martins, Margarida

    2013-01-01

    Aspergillus fumigatus has been shown to form biofilms that are associated with adaptive antifungal resistance mechanisms. These include multidrug efflux pumps, heat shock proteins, and extracellular matrix (ECM). ECM is a key structural and protective component of microbial biofilms and in bacteria has been shown to contain extracellular DNA (eDNA). We therefore hypothesized that A. fumigatus biofilms also possess eDNA as part of the ECM, conferring a functional role. Fluorescence microscopy and quantitative PCR analyses demonstrated the presence of eDNA, which was released phase dependently (8 autolysis, were significantly upregulated as the biofilm matured and that inhibition of chitinases affected biofilm growth and stability, indicating mechanistically that autolysis was possibly involved. Finally, using checkerboard assays, it was shown that combinational treatment of biofilms with DNase plus amphotericin B and caspofungin significantly improved antifungal susceptibility. Collectively, these data show that eDNA is an important structural component of A. fumigatus ECM that is released through autolysis, which is important for protection from environmental stresses, including antifungal therapy. PMID:23314962

  15. Identifying sequential substrate binding at the single-molecule level by enzyme mechanical stabilization.

    Science.gov (United States)

    Rivas-Pardo, Jaime Andrés; Alegre-Cebollada, Jorge; Ramírez-Sarmiento, César A; Fernandez, Julio M; Guixé, Victoria

    2015-01-01

    Enzyme-substrate binding is a dynamic process intimately coupled to protein structural changes, which in turn changes the unfolding energy landscape. By the use of single-molecule force spectroscopy (SMFS), we characterize the open-to-closed conformational transition experienced by the hyperthermophilic adenine diphosphate (ADP)-dependent glucokinase from Thermococcus litoralis triggered by the sequential binding of substrates. In the absence of substrates, the mechanical unfolding of TlGK shows an intermediate 1, which is stabilized in the presence of Mg·ADP(-), the first substrate to bind to the enzyme. However, in the presence of this substrate, an additional unfolding event is observed, intermediate 1*. Finally, in the presence of both substrates, the unfolding force of intermediates 1 and 1* increases as a consequence of the domain closure. These results show that SMFS can be used as a powerful experimental tool to investigate binding mechanisms of different enzymes with more than one ligand, expanding the repertoire of protocols traditionally used in enzymology.

  16. Finite element analysis of mechanics of lateral transmission of force in single muscle fiber.

    Science.gov (United States)

    Zhang, Chi; Gao, Yingxin

    2012-07-26

    Most of the myofibers in long muscles of vertebrates terminate within fascicles without reaching either end of the tendon, thus force generated in myofibers has to be transmitted laterally through the extracellular matrix (ECM) to adjacent fibers; which is defined as the lateral transmission of force in skeletal muscles. The goal of this study was to determine the mechanisms of lateral transmission of force between the myofiber and ECM. In this study, a 2D finite element model of single muscle fiber was developed to study the effects of mechanical properties of the endomysium and the tapered ends of myofiber on lateral transmission of force. Results showed that most of the force generated is transmitted near the end of the myofiber through shear to the endomysium, and the force transmitted to the end of the model increases with increased stiffness of ECM. This study also demonstrated that the tapered angle of the myofiber ends can reduce the stress concentration near the myofiber end while laterally transmitting force efficiently. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Modification of mechanical properties of single crystal aluminum oxide by ion beam induced structural changes

    International Nuclear Information System (INIS)

    Ensinger, W.; Nowak, R.; Horino, Y.; Baba, K.

    1993-01-01

    The mechanical behaviour of ceramics is essentially determined by their surface qualities. As a surface modification technique, ion implantation provides the possibility to modify the mechanical properties of ceramics. Highly energetic ions are implanted into the near-surface region of a material and modify its composition and structure. Ions of aluminum, oxygen, nickel and tantalum were implanted into single-crystal α-aluminum oxide. Three-point bending tests showed that an increase in flexural strength of up to 30% could be obtained after implantation of aluminum and oxygen. Nickel and tantalum ion implantation increased the fracture toughness. Indentation tests with Knoop and Vickers diamonds and comparison of the lengths of the developed radial cracks showed that ion implantation leads to a reaction in cracking. The observed effects are assigned to radiation induced structural changes of the ceramic. Ion bombardment leads to radiation damage and formation of compressive stress. In case of tantalum implantation, the implanted near-surface zone becomes amorphous. These effects make the ceramic more resistant to fracture. (orig.)

  18. On the Mechanical Behavior of a New Single-Crystal Superalloy for Industrial Gas Turbine Applications

    Science.gov (United States)

    Sato, Atsushi; Moverare, Johan J.; Hasselqvist, Magnus; Reed, Roger C.

    2012-07-01

    The mechanical behavior of a new single-crystal nickel-based superalloy for industrial gas turbine (IGT) applications is studied under creep and out-of-phase (OP) thermomechanical fatigue (TMF) conditions. Neutron diffraction methods and thermodynamic modeling are used to quantify the variation of the gamma prime ( γ') strengthening phase around the γ' solvus temperature; these aid the design of primary aging heat treatments to develop either uniform or bimodal microstructures of the γ' phase. Under creep conditions in the temperature range 1023 K to 1123 K (750 °C to 850 °C), with stresses between 235 to 520 MPa, the creep performance is best with a finer and uniform γ' microstructure. On the other hand, the OP TMF performance improves when the γ' precipitate size is larger. Thus, the micromechanical degradation mechanisms occurring during creep and TMF are distinct. During TMF, localized shear banding occurs with the γ' phase penetrated by dislocations; however, during creep, the dislocation activity is restricted to the matrix phase. The factors controlling TMF resistance are rationalized.

  19. Single-molecule FRET unveils induced-fit mechanism for substrate selectivity in flap endonuclease 1

    KAUST Repository

    Rashid, Fahad

    2017-02-23

    Human flap endonuclease 1 (FEN1) and related structure-specific 5\\'nucleases precisely identify and incise aberrant DNA structures during replication, repair and recombination to avoid genomic instability. Yet, it is unclear how the 5\\'nuclease mechanisms of DNA distortion and protein ordering robustly mediate efficient and accurate substrate recognition and catalytic selectivity. Here, single-molecule sub-millisecond and millisecond analyses of FEN1 reveal a protein-DNA induced-fit mechanism that efficiently verifies substrate and suppresses off-target cleavage. FEN1 sculpts DNA with diffusion-limited kinetics to test DNA substrate. This DNA distortion mutually \\'locks\\' protein and DNA conformation and enables substrate verification with extreme precision. Strikingly, FEN1 never misses cleavage of its cognate substrate while blocking probable formation of catalytically competent interactions with noncognate substrates and fostering their pre-incision dissociation. These findings establish FEN1 has practically perfect precision and that separate control of induced-fit substrate recognition sets up the catalytic selectivity of the nuclease active site for genome stability.

  20. A structural mechanics study of single-walled carbon nanotubes generalized from atomistic simulation.

    Science.gov (United States)

    Chen, Xi; Cao, Guoxin

    2006-02-28

    A new structural mechanics model is developed to closely duplicate the atomic configuration and behaviours of single-walled carbon nanotubes (SWCNTs). The SWCNTs are effectively represented by a space frame, where primary and secondary beams are used to bridge the nearest and next-nearest carbon atoms, to mimic energies associated with bond stretching and angle variation, respectively. The elastic properties of the frame components are generalized from molecular dynamics (MD) simulation based on an accurate ab initio force field, and numerical analyses of tension, bending, and torsion are carried out on nine different SWCNTs. The space-frame model also closely duplicates the buckling behaviours of SWCNTs in torsion and bending. In addition, by repeating the same process with continuum shell and beam models, new elastic and section parameters are fitted from the MD benchmark experiments. As an application, all three models are employed to study the thermal vibration behaviours of SWCNTs, and excellent agreements with MD analyses are found. The present analysis is a systematic structural mechanics attempt to fit SWCNT properties for several basic deformation modes and applicable to a variety of SWCNTs. The continuum models and fitted parameters may be used to effectively simulate the overall deformation behaviours of SWCNTs at much larger length- and timescales than pure MD analysis.

  1. Single Vacuum Bagging and Autoclave Curing System Influence on Physical and Mechanical Properties of Phenolic Composites

    Directory of Open Access Journals (Sweden)

    M.A. Mirzapour

    2010-12-01

    Full Text Available Industrial production of thermoset composite components involves the application of a vacuum bagging and autoclave pressure to minimize void percentage, usually to less than 5%. Phenolic resin systems generate water as a reaction byproduct via condensation reactions during curing at elevated temperatures. In this paper, vacuum bagging and simple manufactured autoclave curing systems are used for manufacturing of asbestos/phenolic composites and the effects of processing conditions on manufactured composites are investigated. The traditional single-vacuum-bag process is unable to manage the volatiles effectively, resulting in inferior laminates having voids. The autoclave process cure cycle (temperature/pressure profiles for the selected composite system is designed to emit volatiles during curing reactions effectively and produce composites with low void contents and excellent mechanical properties. Laminate consolidation quality is characterized by optical photomicrography for the cross-sections and measurements of void content and mechanical properties. The void content of phenolic composites as opposed to other composites increases as pressure increases up to 3 bar and it is then decreased beyond it. A product of 124% lower void content, 13% higher density, 24% higher flexural strength and 27% higher flexural modulus can be fabricated in composites obtainedby autoclave processing.

  2. Mechanical properties of single nanostructures investigated by in-situ AFM and micro-XRD

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, Thomas; Scheler, Thomas; Magalhaes-Paniago, Rogerio; Metzger, Till Hartmut [ESRF, Grenoble (France)

    2010-07-01

    In recent years, nanostructures attracted enormous attention due to size-effects influencing the structural, optical, electrical, and mechanical properties of materials with low dimensions. Concerning the mechanical properties mainly the plastic regime was explored showing a trend that ''smaller is stronger''. In contrast, studies of the elastic behaviour of nanowires revealed contradictory results concerning the influence of size-effects on the elasticity. To investigate single nanoobjects in the elastic regime, we combined an in-situ AFM with XRD in a microfocused beam. The AFM is used to image the sample surface, to select an individual nanostructure, and to apply pressure on a chosen object. Due to the interaction between the AFM-tip and the compressed object the resonance frequency of the AFM force sensor shifts to larger values enabling us to derive the stiffness of the contact area. Simultaneous to the pressure application, XRD images around a pre-defined Bragg peak are recorded. These images allow for the determination of the elastic lattice parameter change in-situ. From the contact stiffness and the lattice parameter change, the Young modulus of an individual nanoobject is derived. Here, we present results both for SiGe islands grown by liquid-phase epitaxy on Si wafers and GaAs nanorods created by selective-area metalorganic vapor phase epitaxy on GaAs substrates.

  3. Microcontroller Based Proportional Derivative Plus Conditional Integral Controller for Electro-Mechanical Dual Acting Pulley Continuously Variable Transmission Ratio Control

    Science.gov (United States)

    Budianto, A.; Tawi, K. B.; Hussein, M.; Supriyo, B.; Ariyono, S.; Che Kob, M. S.; Ezlamy Zulkifli, Mohd; K, Khairuldean A.; Daraoh, Aishah

    2012-09-01

    Electro-Mechanical Dual Acting Pulley (EMDAP) Continuously Variable Transmission (CVT) is a transmission utilized by electro-mechanical actuated system. It has a potential to reduce energy consumption because it only needs power during changing CVT ratio and no power is needed to maintain CVT ratio due to self lock mechanism design. This paper proposed simple proportional derivative plus conditional integral (PDCI) controller to control EMDAP CVT ratio which can be simply implemented on a microcontroller. This proposed controller used Astrom-Hagglund method and Ziegler-Nichols formula to tune PDCI gain. The Proportional Derivative controller is directly activated from the start but Integral controller is only activated when the error value reaches error value setting point. Simulation using Matlab/Simulink software was conducted to evaluate PDCI system performance. The simulation results showed PDCI controller has ability to perform maximum overshoot 0.1%, 0.001 steady state error and 0.5s settling time. For clamping condition, settling time is about 11.46s during changing ratio from 2.0 to 0.7, while for release condition, settling time is about 8.33s during changing ratio from 0.7 to 2.0.

  4. Single sample expression-anchored mechanisms predict survival in head and neck cancer.

    Directory of Open Access Journals (Sweden)

    Xinan Yang

    2012-01-01

    Full Text Available Gene expression signatures that are predictive of therapeutic response or prognosis are increasingly useful in clinical care; however, mechanistic (and intuitive interpretation of expression arrays remains an unmet challenge. Additionally, there is surprisingly little gene overlap among distinct clinically validated expression signatures. These "causality challenges" hinder the adoption of signatures as compared to functionally well-characterized single gene biomarkers. To increase the utility of multi-gene signatures in survival studies, we developed a novel approach to generate "personal mechanism signatures" of molecular pathways and functions from gene expression arrays. FAIME, the Functional Analysis of Individual Microarray Expression, computes mechanism scores using rank-weighted gene expression of an individual sample. By comparing head and neck squamous cell carcinoma (HNSCC samples with non-tumor control tissues, the precision and recall of deregulated FAIME-derived mechanisms of pathways and molecular functions are comparable to those produced by conventional cohort-wide methods (e.g. GSEA. The overlap of "Oncogenic FAIME Features of HNSCC" (statistically significant and differentially regulated FAIME-derived genesets representing GO functions or KEGG pathways derived from HNSCC tissue among three distinct HNSCC datasets (pathways:46%, p<0.001 is more significant than the gene overlap (genes:4%. These Oncogenic FAIME Features of HNSCC can accurately discriminate tumors from control tissues in two additional HNSCC datasets (n = 35 and 91, F-accuracy = 100% and 97%, empirical p<0.001, area under the receiver operating characteristic curves = 99% and 92%, and stratify recurrence-free survival in patients from two independent studies (p = 0.0018 and p = 0.032, log-rank. Previous approaches depending on group assignment of individual samples before selecting features or learning a classifier are limited by design to

  5. A mini-overview of single muscle fibre mechanics: the effects of age, inactivity and exercise in animals and humans.

    Science.gov (United States)

    Jee, Hyunseok; Kim, Jong-Hee

    2017-09-05

    Many basic movements of living organisms are dependent on muscle function. Muscle function allows for the coordination and harmonious integrity of movement that is necessary for various biological processes. Gross and fine motor skills are both regulated at the micro-level (single muscle fibre level), controlled by neuronal regulation, and it is therefore important to understand muscle function at both micro- and macro-levels to understand the overall movement of living organisms. Single muscle mechanics and the cellular environment of muscles fundamentally allow for the harmonious movement of our bodies. Indeed, a clear understanding of the functionality of muscle at the micro-level is indispensable for explaining muscular function at the macro-(whole gross muscle) level. By investigating single muscle fibre mechanics, we can also learn how other factors such Ca2+ kinetics, enzyme activity and contractile proteins can contribute to muscle mechanics at the micro- and macro-levels. Further, we can also describe how aging affects the capacity of skeletal muscle cells, as well as how exercise can prevent aging-based sarcopenia and frailty. The purpose of this review is to introduce and summarise the current knowledge of single muscle fibre mechanics in light of aging and inactivity. We then describe how exercise mitigates negative muscle adaptations that occur under those circumstances. In addition, single muscle fibre mechanics in both animal and human models are discussed.

  6. Mechanical performance of cement- and screw-retained all-ceramic single crowns on dental implants.

    Science.gov (United States)

    Obermeier, Matthias; Ristow, Oliver; Erdelt, Kurt; Beuer, Florian

    2018-03-01

    This in-vitro study was performed to compare the contact wear, fracture strength and failure mode of implant-supported all-ceramic single crowns manufactured with various fabrication and fixation concepts. Fifty dental implants (Conelog Ø 4,3mm/L11mm, Camlog Biotechnologies AG) were embedded and treated with all-ceramic molar single-crowns. Three groups received hand-layered zirconia crowns (IPS e.max Ceram/ IPS e.max ZirCAD, Ivoclar Vivadent AG): CZL (cement-retained zirconia-based layered) group crowns were cemented conventionally, SZL (screw-retained zirconia-based layered) group crowns were screw-retained, MZL (modified zirconia-based layered) group crowns showed a different coping design with screw retention. The specimens of SST (screw-retained sintering-technique) and SFL (screw-retained full-contour lithium-disilicate) group were CAD/CAM (Computer-aided design/computer-aided manufacturing) fabricated in the sintering technique (IPS e.max ZirCAD/IPS e.max CAD, Ivoclar Vivadent AG) and full-contour of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent AG) respectively and screw-retained. All specimens underwent artificial aging, load until failure and a scanning electron microscopy (SEM) analysis. The received data were statistically compared (one-way ANOVA; Student-Newman-Keuls test; Mann-Whitney U-test) at a significance level of 5%. Mouth-motion fatigue testing caused two abutment fractures (SST group and SZL group) and two chipping events (CZL group). Specimens of MZL group showed statistically significant less contact wear compared to the other groups (pCAD/CAM fabricated specimens towards manually veneered components. The mode of retention did not influence the fracture resistance but the failure patterns of the specimens. CAD/CAM milled lithium-disilicate crowns seemed to be a preserving factor for dental implants. The mode of retention and veneering influences the mechanical performance of implant-supported single crowns.

  7. Single-molecule exploration of photoprotective mechanisms in light-harvesting complexes

    Science.gov (United States)

    Yang, Hsiang-Yu; Schlau-Cohen, Gabriela S.; Gwizdala, Michal; Krüger, Tjaart; Xu, Pengqi; Croce, Roberta; van Grondelle, Rienk; Moerner, W. E.

    2015-03-01

    Plants harvest sunlight by converting light energy to electron flow through the primary events in photosynthesis. One important question is how the light harvesting machinery adapts to fluctuating sunlight intensity. As a result of various regulatory processes, efficient light harvesting and photoprotection are balanced. Some of the biological steps in the photoprotective processes have been extensively studied and physiological regulatory factors have been identified. For example, the effect of lumen pH in changing carotenoid composition has been explored. However, the importance of photophysical dynamics in the initial light-harvesting steps and its relation to photoprotection remain poorly understood. Conformational and excited-state dynamics of multi-chromophore pigment-protein complexes are often difficult to study and limited information can be extracted from ensemble-averaged measurements. To address the problem, we use the Anti-Brownian ELectrokinetic (ABEL) trap to investigate the fluorescence from individual copies of light-harvesting complex II (LHCII), the primary antenna protein in higher plants, in a solution-phase environment. Perturbative surface immobilization or encapsulation schemes are avoided, and therefore the intrinsic dynamics and heterogeneity in the fluorescence of individual proteins are revealed. We perform simultaneous measurements of fluorescence intensity (brightness), excited-state lifetime, and emission spectrum of single trapped proteins. By analyzing the correlated changes between these observables, we identify forms of LHCII with different fluorescence intensities and excited-state lifetimes. The distinct forms may be associated with different energy dissipation mechanisms in the energy transfer chain. Changes of relative populations in response to pH and carotenoid composition are observed, which may extend our understanding of the molecular mechanisms of photoprotection.

  8. Effectiveness of ACT-Based Parenting Training to Mothers on the Depression of Children with Cleft Lip and Palate: A Single Subject Study

    Directory of Open Access Journals (Sweden)

    محمد صالح فقیهی

    2017-06-01

    Full Text Available The purpose of this study was to determine the effectiveness of Parenting Training based on Acceptance and Commitment Therapy (ACT to mothers on the depression of children with cleft lip and palate. The research method was based on a single case and individual intervention study. The sample was constituted of 65 Isfahanian children with cleft lip and palate. Parenting skills based on ACT were taught to five mothers of children with cleft lip and palate who achieved the minimum score in screening. After three baseline sessions for each child, ACT parenting skills were taught to their mothers in 8 individual sessions companied with testing the child’s depression in every session. Three follow-up sessions after 15 days, 1 month and 3 months were set to evaluate children’s depression. The Kovacs Children’s Depression Inventory (CDI was used to test the children’s depression. The results were analyzed with visual analysis and descriptive statistics. This particular intervention was effective on depression. Based on the results of the present study, it can be concluded that ACT parenting training to mothers of children with cleft lips and palates was effective on reducing depression and that an on-time intervention can improve these children's depression.

  9. Three mechanisms model of shale gas in real state transport through a single nanopore

    Science.gov (United States)

    Li, Dongdong; Zhang, Yanyu; Sun, Xiaofei; Li, Peng; Zhao, Fengkai

    2018-02-01

    At present, the apparent permeability models of shale gas consider only the viscous flow and Knudsen diffusion of free gas, but do not take into account the influence of surface diffusion. Moreover, it is assumed that shale gas is in ideal state. In this paper, shale gas is assumed in real state, a new apparent permeability model for shale gas transport through a single nanopore is developed that captures many important migration mechanisms, such as viscous flow and Knudsen diffusion of free gas, surface diffusion of adsorbed gas. According to experimental data, the accuracy of apparent permeability model was verified. What’s more, the effects of pressure and pore radius on apparent permeability, and the effects on the permeability fraction of viscous flow, Knudsen diffusion and surface diffusion were analysed, separately. Finally, the results indicate that the error of the developed model in this paper was 3.02%, which is less than the existing models. Pressure and pore radius seriously affect the apparent permeability of shale gas. When the pore radius is small or pressure is low, the surface diffusion cannot be ignored. When the pressure and the pore radius is big, the viscous flow occupies the main position.

  10. Microstructures and mechanical properties of β-NiAlHf coated single crystal superalloy

    International Nuclear Information System (INIS)

    Gong, Xueyuan; Yang, Yonghong; Ma, Yue; Peng, Hui; Guo, Hongbo

    2016-01-01

    A β-NiAlHf coating was deposited by electron beam physical vapor deposition (EB-PVD) onto single crystal (SC) superalloy substrate. The microstructure evolution of the NiAlHf coating after annealing at 1100 °C was investigated and the mechanical properties of the coated substrate were also concerned. The crack initiation and propagation behavior of the coated substrate during three-point bending was studied. An interdiffusion zone (IDZ) was formed between the coating and substrate and the hardness of the precipitates in the IDZ layer was relatively higher than that of the coating and the substrate. The annealed specimen during bending revealed different crack initiation and propagation behavior from the uncoated specimen. Cracks were initiated at the carbides in the uncoated alloy. For the coated specimen after 10 h annealing, cracks were initiated mostly in the IDZ layer, due to the presence of μ-TCP phases. For the coated specimen after 50 h annealing, cracks were generated at the top of triangle-shaped γ′-Ni 3 Al phases where stress concentration occurred, which finally propagated into the substrate, leading to the reduction of the alloy in strength.

  11. Tribology. Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts.

    Science.gov (United States)

    Gosvami, N N; Bares, J A; Mangolini, F; Konicek, A R; Yablon, D G; Carpick, R W

    2015-04-03

    Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converters over time. Using atomic force microscopy in ZDDP-containing lubricant base stock at elevated temperatures, we monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts. Surface-based nucleation, growth, and thickness saturation of patchy tribofilms were observed. The growth rate increased exponentially with either applied compressive stress or temperature, consistent with a thermally activated, stress-assisted reaction rate model. Although some models rely on the presence of iron to catalyze tribofilm growth, the films grew regardless of the presence of iron on either the tip or substrate, highlighting the critical role of stress and thermal activation. Copyright © 2015, American Association for the Advancement of Science.

  12. Mechanical properties of ANTRIX balloon film and fabrication of single cap large volume balloons

    Science.gov (United States)

    Suneel Kumar, B.; Sreenivasan, S.; Subba Rao, J. V.; Manchanda, R. K.

    2008-11-01

    The zero pressure plastic balloons used for high altitude studies are generally made from polyethylene material. Tensile properties of the thin film polymer are the key parameters for material selection due to extremely low temperature of -90 °C encountered by the balloons in the tropopause region during the ascent at equatorial latitudes. The physical and structural properties of the material determine the uniformity of the stress distribution over the entire shell. Load stresses from the suspended load propagate via load tapes heat sealed along with the gore seals as per the balloon design. A balance between this heat seal strength and the film strength is a desirable property of the basic resin in terms of the bubble strength, gauge uniformity, and long-term storage properties. In addition, the design of the top shell of the balloon and its stress distribution play an important role since only a fraction of the balloon is deployed during the filling operation and the ascent. In this paper we describe the mechanical properties of the 'ANTRIX' film developed by us and the optimized design of single cap balloons, which have been successfully used in our experiments over the past 5 years.

  13. Strength and Failure Mechanism of Composite-Steel Adhesive Bond Single Lap Joints

    Directory of Open Access Journals (Sweden)

    Kai Wei

    2018-01-01

    Full Text Available Carbon fiber-reinforced plastics- (CFRP- steel single lap joints with regard to tensile loading with two levels of adhesives and four levels of overlap lengths were experimentally analyzed and numerically simulated. Both joint strength and failure mechanism were found to be highly dependent on adhesive type and overlap length. Joints with 7779 structural adhesive were more ductile and produced about 2-3 kN higher failure load than MA830 structural adhesive. Failure load with the two adhesives increased about 147 N and 176 N, respectively, with increasing 1 mm of the overlap length. Cohesion failure was observed in both types of adhesive joints. As the overlap length increased, interface failure appeared solely on the edge of the overlap in 7779 adhesive joints. Finite element analysis (FEA results revealed that peel and shear stress distributions were nonuniform, which were less severe as overlap length increased. Severe stress concentration was observed on the overlap edge, and shear failure of the adhesive was the main reason for the adhesive failure.

  14. Single Layer Bismuth Iodide: Computational Exploration of Structural, Electrical, Mechanical and Optical Properties

    Science.gov (United States)

    Ma, Fengxian; Zhou, Mei; Jiao, Yalong; Gao, Guoping; Gu, Yuantong; Bilic, Ante; Chen, Zhongfang; Du, Aijun

    2015-12-01

    Layered graphitic materials exhibit new intriguing electronic structure and the search for new types of two-dimensional (2D) monolayer is of importance for the fabrication of next generation miniature electronic and optoelectronic devices. By means of density functional theory (DFT) computations, we investigated in detail the structural, electronic, mechanical and optical properties of the single-layer bismuth iodide (BiI3) nanosheet. Monolayer BiI3 is dynamically stable as confirmed by the computed phonon spectrum. The cleavage energy (Ecl) and interlayer coupling strength of bulk BiI3 are comparable to the experimental values of graphite, which indicates that the exfoliation of BiI3 is highly feasible. The obtained stress-strain curve shows that the BiI3 nanosheet is a brittle material with a breaking strain of 13%. The BiI3 monolayer has an indirect band gap of 1.57 eV with spin orbit coupling (SOC), indicating its potential application for solar cells. Furthermore, the band gap of BiI3 monolayer can be modulated by biaxial strain. Most interestingly, interfacing electrically active graphene with monolayer BiI3 nanosheet leads to enhanced light absorption compared to that in pure monolayer BiI3 nanosheet, highlighting its great potential applications in photonics and photovoltaic solar cells.

  15. Assessment of continuum mechanics models in predicting buckling strains of single-walled carbon nanotubes.

    Science.gov (United States)

    Zhang, Y Y; Wang, C M; Duan, W H; Xiang, Y; Zong, Z

    2009-09-30

    This paper presents an assessment of continuum mechanics (beam and cylindrical shell) models in the prediction of critical buckling strains of axially loaded single-walled carbon nanotubes (SWCNTs). Molecular dynamics (MD) simulation results for SWCNTs with various aspect (length-to-diameter) ratios and diameters will be used as the reference solutions for this assessment exercise. From MD simulations, two distinct buckling modes are observed, i.e. the shell-type buckling mode, when the aspect ratios are small, and the beam-type mode, when the aspect ratios are large. For moderate aspect ratios, the SWCNTs buckle in a mixed beam-shell mode. Therefore one chooses either the beam or the shell model depending on the aspect ratio of the carbon nanotubes (CNTs). It will be shown herein that for SWCNTs with long aspect ratios, the local Euler beam results are comparable to MD simulation results carried out at room temperature. However, when the SWCNTs have moderate aspect ratios, it is necessary to use the more refined nonlocal beam theory or the Timoshenko beam model for a better prediction of the critical strain. For short SWCNTs with large diameters, the nonlocal shell model with the appropriate small length scale parameter can provide critical strains that are in good agreement with MD results. However, for short SWCNTs with small diameters, more work has to be done to refine the nonlocal cylindrical shell model for better prediction of critical strains.

  16. Altered cell mechanics from the inside: dispersed single wall carbon nanotubes integrate with and restructure actin.

    Science.gov (United States)

    Holt, Brian D; Shams, Hengameh; Horst, Travis A; Basu, Saurav; Rape, Andrew D; Wang, Yu-Li; Rohde, Gustavo K; Mofrad, Mohammad R K; Islam, Mohammad F; Dahl, Kris Noel

    2012-05-23

    With a range of desirable mechanical and optical properties, single wall carbon nanotubes (SWCNTs) are a promising material for nanobiotechnologies. SWCNTs also have potential as biomaterials for modulation of cellular structures. Previously, we showed that highly purified, dispersed SWCNTs grossly alter F-actin inside cells. F-actin plays critical roles in the maintenance of cell structure, force transduction, transport and cytokinesis. Thus, quantification of SWCNT-actin interactions ranging from molecular, sub-cellular and cellular levels with both structure and function is critical for developing SWCNT-based biotechnologies. Further, this interaction can be exploited, using SWCNTs as a unique actin-altering material. Here, we utilized molecular dynamics simulations to explore the interactions of SWCNTs with actin filaments. Fluorescence lifetime imaging microscopy confirmed that SWCNTs were located within ~5 nm of F-actin in cells but did not interact with G-actin. SWCNTs did not alter myosin II sub-cellular localization, and SWCNT treatment in cells led to significantly shorter actin filaments. Functionally, cells with internalized SWCNTs had greatly reduced cell traction force. Combined, these results demonstrate direct, specific SWCNT alteration of F-actin structures which can be exploited for SWCNT-based biotechnologies and utilized as a new method to probe fundamental actin-related cellular processes and biophysics.

  17. Altered Cell Mechanics from the Inside: Dispersed Single Wall Carbon Nanotubes Integrate with and Restructure Actin

    Directory of Open Access Journals (Sweden)

    Mohammad F. Islam

    2012-05-01

    Full Text Available With a range of desirable mechanical and optical properties, single wall carbon nanotubes (SWCNTs are a promising material for nanobiotechnologies. SWCNTs also have potential as biomaterials for modulation of cellular structures. Previously, we showed that highly purified, dispersed SWCNTs grossly alter F-actin inside cells. F-actin plays critical roles in the maintenance of cell structure, force transduction, transport and cytokinesis. Thus, quantification of SWCNT-actin interactions ranging from molecular, sub-cellular and cellular levels with both structure and function is critical for developing SWCNT-based biotechnologies. Further, this interaction can be exploited, using SWCNTs as a unique actin-altering material. Here, we utilized molecular dynamics simulations to explore the interactions of SWCNTs with actin filaments. Fluorescence lifetime imaging microscopy confirmed that SWCNTs were located within ~5 nm of F-actin in cells but did not interact with G-actin. SWCNTs did not alter myosin II sub-cellular localization, and SWCNT treatment in cells led to significantly shorter actin filaments. Functionally, cells with internalized SWCNTs had greatly reduced cell traction force. Combined, these results demonstrate direct, specific SWCNT alteration of F-actin structures which can be exploited for SWCNT-based biotechnologies and utilized as a new method to probe fundamental actin-related cellular processes and biophysics.

  18. Studies of single walled carbon nanotubes for biomedical, mechanical and electrical applications using atomic force microscopy

    Science.gov (United States)

    Lahiji, Roya Roientan

    The promise of carbon nanotubes to provide high-strength composites implies that carbon nanotubes might find widespread use throughout the world, implying that humans everywhere will be exposed to carbon nanotube-containing materials. In order to study what effects if any carbon nanotubes might have on the function of living cells, we have studied the association of single stranded DNA (ssDNA) with single wall carbon nanotubes (SWCNTs) as a first step toward understanding the interaction of SWCNTs with living matter. Studies have been performed on both as-received and chemically oxidized SWCNTs to better understand the preferential association of ssDNA with SWCNTs. Samples of T30 ssDNA:SWCNT were examined under ambient conditions using non-contact Atomic Force Microscopy (AFM)) techniques. AFM images of well-dispersed, as-received SWCNTs revealed isolated features on the SWCNT that are 1.4 to 2.8 nm higher than the bare SWCNT itself. X-ray Photoemission Spectroscopy (XPS) confirmed these features to be T30 ssDNA in nature. Chemically oxidizing SWCNTs before dispersion by sonication is found to be an effective way to increase the number of T30 ssDNA features. A series of experiments showed that free radical scavengers such as ascorbic acid and trolox can effectively prevent the conjugation of ssDNA to SWCNTs, suggesting a significant role of free radicals in this association. Also hybridization of the complimentary ssDNA sequences showed the covalent nature of this association. These results are important to understanding the precise mechanism of ssDNA:SWCNT association and provide valuable information for future use in electronics, biosensors and as a possible drug carrier into individual cells. If SWCNTs are used in biosensor or circuit design applications then it is important to note how much energy can be stored in a SWCNT based on its shape and configuration before a permanent damage is introduced to it. Therefore a study has been done on bending SWCNTs into

  19. The Antiviral Mechanism of an Influenza A Virus Nucleoprotein-Specific Single-Domain Antibody Fragment

    Energy Technology Data Exchange (ETDEWEB)

    Hanke, Leo; Knockenhauer, Kevin E.; Brewer, R. Camille; van Diest, Eline; Schmidt, Florian I.; Schwartz, Thomas U.; Ploegh, Hidde L. (Whitehead); (MIT)

    2016-12-13

    Alpaca-derived single-domain antibody fragments (VHHs) that target the influenza A virus nucleoprotein (NP) can protect cells from infection when expressed in the cytosol. We found that one such VHH, αNP-VHH1, exhibits antiviral activity similar to that of Mx proteins by blocking nuclear import of incoming viral ribonucleoproteins (vRNPs) and viral transcription and replication in the nucleus. We determined a 3.2-Å crystal structure of αNP-VHH1 in complex with influenza A virus NP. The VHH binds to a nonconserved region on the body domain of NP, which has been associated with binding to host factors and serves as a determinant of host range. Several of the NP/VHH interface residues determine sensitivity of NP to antiviral Mx GTPases. The structure of the NP/αNP-VHH1 complex affords a plausible explanation for the inhibitory properties of the VHH and suggests a rationale for the antiviral properties of Mx proteins. Such knowledge can be leveraged for much-needed novel antiviral strategies.

    IMPORTANCEInfluenza virus strains can rapidly escape from protection afforded by seasonal vaccines or acquire resistance to available drugs. Additional ways to interfere with the virus life cycle are therefore urgently needed. The influenza virus nucleoprotein is one promising target for antiviral interventions. We have previously isolated alpaca-derived single-domain antibody fragments (VHHs) that protect cells from influenza virus infection if expressed intracellularly. We show here that one such VHH exhibits antiviral activities similar to those of proteins of the cellular antiviral defense (Mx proteins). We determined the three-dimensional structure of this VHH in complex with the influenza virus nucleoprotein and identified the interaction site, which overlaps regions that determine sensitivity of the virus to Mx proteins. Our data define a new vulnerability of influenza virus, help us to better understand the cellular antiviral mechanisms, and

  20. The Antiviral Mechanism of an Influenza A Virus Nucleoprotein-Specific Single-Domain Antibody Fragment.

    Science.gov (United States)

    Hanke, Leo; Knockenhauer, Kevin E; Brewer, R Camille; van Diest, Eline; Schmidt, Florian I; Schwartz, Thomas U; Ploegh, Hidde L

    2016-12-13

    Alpaca-derived single-domain antibody fragments (VHHs) that target the influenza A virus nucleoprotein (NP) can protect cells from infection when expressed in the cytosol. We found that one such VHH, αNP-VHH1, exhibits antiviral activity similar to that of Mx proteins by blocking nuclear import of incoming viral ribonucleoproteins (vRNPs) and viral transcription and replication in the nucleus. We determined a 3.2-Å crystal structure of αNP-VHH1 in complex with influenza A virus NP. The VHH binds to a nonconserved region on the body domain of NP, which has been associated with binding to host factors and serves as a determinant of host range. Several of the NP/VHH interface residues determine sensitivity of NP to antiviral Mx GTPases. The structure of the NP/αNP-VHH1 complex affords a plausible explanation for the inhibitory properties of the VHH and suggests a rationale for the antiviral properties of Mx proteins. Such knowledge can be leveraged for much-needed novel antiviral strategies. Influenza virus strains can rapidly escape from protection afforded by seasonal vaccines or acquire resistance to available drugs. Additional ways to interfere with the virus life cycle are therefore urgently needed. The influenza virus nucleoprotein is one promising target for antiviral interventions. We have previously isolated alpaca-derived single-domain antibody fragments (VHHs) that protect cells from influenza virus infection if expressed intracellularly. We show here that one such VHH exhibits antiviral activities similar to those of proteins of the cellular antiviral defense (Mx proteins). We determined the three-dimensional structure of this VHH in complex with the influenza virus nucleoprotein and identified the interaction site, which overlaps regions that determine sensitivity of the virus to Mx proteins. Our data define a new vulnerability of influenza virus, help us to better understand the cellular antiviral mechanisms, and provide a well-characterized tool to

  1. Advanced mechanisms for the promotion of renewable energy-Models for the future evolution of the German Renewable Energy Act

    International Nuclear Information System (INIS)

    Langniss, Ole; Diekmann, Jochen; Lehr, Ulrike

    2009-01-01

    The German Renewable Energy Act (EEG) has been very successful in promoting the deployment of renewable electricity technologies in Germany. The increasing share of EEG power in the generation portfolio, increasing amounts of fluctuating power generation, and the growing European integration of power markets governed by competition calls for a re-design of the EEG. In particular, a more efficient system integration and commercial integration of the EEG power is needed to, e.g. better matching feed-in to demand and avoiding stress on electricity grids. This article describes three different options to improve the EEG by providing appropriate incentives and more flexibility to the promotion mechanism and the quantitative compensation scheme without jeopardising the fast deployment of renewable energy technologies. In the 'Retailer Model', it becomes the responsibility of the end-use retailers to adapt the EEG power to the actual demand of their respective customers. The 'Market Mediator Model' establishes an independent market mediator responsible to market the renewable electricity. This model is the primary choice when new market entrants are regarded as crucial for the better integration of renewable energy and enhanced competition. The 'Optional Bonus Model' relies more on functioning markets since power plant operators can alternatively choose to market the generated electricity themselves with a premium on top of the market price instead of a fixed price

  2. Mechanically Reconfigurable Single-Arm Spiral Antenna Array for Generation of Broadband Circularly Polarized Orbital Angular Momentum Vortex Waves.

    Science.gov (United States)

    Li, Long; Zhou, Xiaoxiao

    2018-03-23

    In this paper, a mechanically reconfigurable circular array with single-arm spiral antennas (SASAs) is designed, fabricated, and experimentally demonstrated to generate broadband circularly polarized orbital angular momentum (OAM) vortex waves in radio frequency domain. With the symmetrical and broadband properties of single-arm spiral antennas, the vortex waves with different OAM modes can be mechanically reconfigurable generated in a wide band from 3.4 GHz to 4.7 GHz. The prototype of the circular array is proposed, conducted, and fabricated to validate the theoretical analysis. The simulated and experimental results verify that different OAM modes can be effectively generated by rotating the spiral arms of single-arm spiral antennas with corresponding degrees, which greatly simplify the feeding network. The proposed method paves a reconfigurable way to generate multiple OAM vortex waves with spin angular momentum (SAM) in radio and microwave satellite communication applications.

  3. Development of the SAIT single-port surgical access robot--slave arm based on RCM mechanism.

    Science.gov (United States)

    Roh, Se-gon; Lee, Younbaek; Lee, Jongwon; Ha, Taesin; Sang, Taejun; Moon, Kyung-Won; Lee, Minhyong; Choi, Jung-yun

    2015-01-01

    An innovative single-port surgical robot has recently been developed by the Samsung Advanced Institute of Technology (SAIT). The robot can reach various surgical sites inside the abdominal cavity from a single incision on the body. It has two 7-DOF surgical tools, a 3-DOF endoscope, a flexible hyper-redundant 6-DOF guide tube, and a 6-DOF manipulator. This paper primarily focuses on the manipulator, called a slave arm, which is capable of setting the location of a Remote Center Motion (RCM) point. Because the surgical tools can explore the abdominal area through a small incision point when the RCM point is aligned with the incision area, the RCM mechanism is an integral part of the manipulator for single-port surgery. The mechanical feature, operational principle, control method, and the system architecture of the slave arm are introduced in this paper. In addition, manipulation experiments conducted validate its efficacy.

  4. Experimental study of micro-milling mechanism and surface quality of a nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Qi; Gong, Yadong; Zhou, Yun Guang; Wen, Xue Long [School of Mechanical Engineering and Automation, Northeastern University, Shenyang (China)

    2017-01-15

    Micro-milling is widely used as a method for machining of micro-parts with high precision and efficiency. Taking the nickel-based single-crystal superalloy DD98 as the research object, the crystal characteristics of single-crystal materials were analysed, and the removal mechanism of single-crystal micro-milled parts was described. Based on molecular dynamics, a simulation model for nickel-based single-crystal superalloy DD98 micro-milling was established. Based on the response surface method of central composite design, the influences of spindle speed, feed rate, and milling depth on the surface roughness were examined, and a second-order regression model of the DD98 surface roughness was established. Using analysis of variance and the residuals of the model, a significant influence on surface roughness was found in the following order from large to small: Feed rate, spindle speed, and milling depth. Comparisons were conducted between the micro-milling experimental values and the predicted model values for different process parameters. The results show that the model fit is relatively high, and the adaptability is good. Scanning electron microscopy analysis of the micro-milling surfaces was performed to verify the slip and the removal mechanism of single-crystal materials. These results offer a theoretical reference and experimental basis for micro-milling of single-crystal materials.

  5. Single particle tracking-based reaction progress kinetic analysis reveals a series of molecular mechanisms of cetuximab-induced EGFR processes in a single living cell.

    Science.gov (United States)

    Kim, Do-Hyeon; Kim, Dong-Kyun; Zhou, Kai; Park, Soyeon; Kwon, Yonghoon; Jeong, Min Gyu; Lee, Nam Ki; Ryu, Sung Ho

    2017-07-01

    Cellular processes occur through the orchestration of multi-step molecular reactions. Reaction progress kinetic analysis (RPKA) can provide the mechanistic details to elucidate the multi-step molecular reactions. However, current tools have limited ability to simultaneously monitor dynamic variations in multiple complex states at the single molecule level to apply RPKA in living cells. In this research, a single particle tracking-based reaction progress kinetic analysis (sptRPKA) was developed to simultaneously determine the kinetics of multiple states of protein complexes in the membrane of a single living cell. The subpopulation ratios of different states were quantitatively (and statistically) reliably extracted from the diffusion coefficient distribution rapidly acquired by single particle tracking at constant and high density over a long period of time using super-resolution microscopy. Using sptRPKA, a series of molecular mechanisms of epidermal growth factor receptor (EGFR) cellular processing induced by cetuximab were investigated. By comprehensively measuring the rate constants and cooperativity of the molecular reactions involving four EGFR complex states, a previously unknown intermediate state was identified that represents the rate limiting step responsible for the selectivity of cetuximab-induced EGFR endocytosis to cancer cells.

  6. Dual-Stack Single-Radio Communication Architecture for UAV Acting As a Mobile Node to Collect Data in WSNs

    Directory of Open Access Journals (Sweden)

    Ali Sayyed

    2015-09-01

    Full Text Available The use of mobile nodes to collect data in a Wireless Sensor Network (WSN has gained special attention over the last years. Some researchers explore the use of Unmanned Aerial Vehicles (UAVs as mobile node for such data-collection purposes. Analyzing these works, it is apparent that mobile nodes used in such scenarios are typically equipped with at least two different radio interfaces. The present work presents a Dual-Stack Single-Radio Communication Architecture (DSSRCA, which allows a UAV to communicate in a bidirectional manner with a WSN and a Sink node. The proposed architecture was specifically designed to support different network QoS requirements, such as best-effort and more reliable communications, attending both UAV-to-WSN and UAV-to-Sink communications needs. DSSRCA was implemented and tested on a real UAV, as detailed in this paper. This paper also includes a simulation analysis that addresses bandwidth consumption in an environmental monitoring application scenario. It includes an analysis of the data gathering rate that can be achieved considering different UAV flight speeds. Obtained results show the viability of using a single radio transmitter for collecting data from the WSN and forwarding such data to the Sink node.

  7. Dual-Stack Single-Radio Communication Architecture for UAV Acting As a Mobile Node to Collect Data in WSNs.

    Science.gov (United States)

    Sayyed, Ali; de Araújo, Gustavo Medeiros; Bodanese, João Paulo; Becker, Leandro Buss

    2015-09-16

    The use of mobile nodes to collect data in a Wireless Sensor Network (WSN) has gained special attention over the last years. Some researchers explore the use of Unmanned Aerial Vehicles (UAVs) as mobile node for such data-collection purposes. Analyzing these works, it is apparent that mobile nodes used in such scenarios are typically equipped with at least two different radio interfaces. The present work presents a Dual-Stack Single-Radio Communication Architecture (DSSRCA), which allows a UAV to communicate in a bidirectional manner with a WSN and a Sink node. The proposed architecture was specifically designed to support different network QoS requirements, such as best-effort and more reliable communications, attending both UAV-to-WSN and UAV-to-Sink communications needs. DSSRCA was implemented and tested on a real UAV, as detailed in this paper. This paper also includes a simulation analysis that addresses bandwidth consumption in an environmental monitoring application scenario. It includes an analysis of the data gathering rate that can be achieved considering different UAV flight speeds. Obtained results show the viability of using a single radio transmitter for collecting data from the WSN and forwarding such data to the Sink node.

  8. Single and two-mode mechanical squeezing of an optically levitated nanodiamond via dressed-state coherence

    Science.gov (United States)

    Ge, Wenchao; Bhattacharya, M.

    2016-10-01

    Nonclassical states of macroscopic objects are promising for ultrasensitive metrology as well as testing quantum mechanics. In this work, we investigate dissipative mechanical quantum state engineering in an optically levitated nanodiamond. First, we study single-mode mechanical squeezed states by magnetically coupling the mechanical motion to a dressed three-level system provided by a nitrogen-vacancy center in the nanoparticle. Quantum coherence between the dressed levels is created via microwave fields to induce a two-phonon transition, which results in mechanical squeezing. Remarkably, we find that in ultrahigh vacuum quantum squeezing is achievable at room temperature with feedback cooling. For moderate vacuum, quantum squeezing is possible with cryogenic temperature. Second, we present a setup for two mechanical modes coupled to the dressed three levels, which results in two-mode squeezing analogous to the mechanism of the single-mode case. In contrast to previous works, our study provides a deterministic method for engineering macroscopic squeezed states without the requirement for a cavity.

  9. Direct correlation of single-molecule properties with bulk mechanical performance for the biomimetic design of polymers.

    Science.gov (United States)

    Chung, Jaeyoon; Kushner, Aaron M; Weisman, Adam C; Guan, Zhibin

    2014-11-01

    For rational design of advanced polymeric materials, it is critical to establish a clear mechanistic link between the molecular structure of a polymer and the emergent bulk mechanical properties. Despite progress towards this goal, it remains a major challenge to directly correlate the bulk mechanical performance to the nanomechanical properties of individual constituent macromolecules. Here, we show a direct correlation between the single-molecule nanomechanical properties of a biomimetic modular polymer and the mechanical characteristics of the resulting bulk material. The multi-cyclic single-molecule force spectroscopy (SMFS) data enabled quantitative derivation of the asymmetric potential energy profile of individual module rupture and re-folding, in which a steep dissociative pathway accounted for the high plateau modulus, while a shallow associative well explained the energy-dissipative hysteresis and dynamic, adaptive recovery. These results demonstrate the potential for SMFS to serve as a guide for future rational design of advanced multifunctional materials.

  10. Discharge mechanisms and electrochemical impedance spectroscopy measurements of single negative and positive lead-acid battery plates

    Energy Technology Data Exchange (ETDEWEB)

    D' Alkaine, C.V. [Group of Electrochemistry and Polymers, Chemistry Department, Federal University of Sao Carlos, 13560-905 Sao Carlos, SP (Brazil); Mengarda, P.; Impinnisi, P.R. [Battery Laboratory, Institute of Technology for Development - LACTEC, Curitiba, PR (Brazil)

    2009-06-01

    This study interpreted open circuit impedance measurements of single negative and positive lead-acid battery plates, which were at different discharge levels and arranged in a four-electrode cell. This was performed in the framework of a proposed general model of charge/discharge reactions, morphological models of active materials, and based on interpretation of the characteristics of single negative and positive plates as measured by electrochemical impedance spectroscopy (EIS). This study shows that the proposed reaction models, morphological characteristics and EIS attributions are compatible with the obtained EIS data. The analysis indicates that negative and positive plate reaction mechanisms cannot be those proposed by the dissolution-precipitation mechanism alone. Rather, the reactions seem to obey the various mechanisms and morphologic ideas proposed in the present paper. It is shown that variations in the resistivity and dielectric constants of discharged films need to be studied in greater detail than film thicknesses to gain a better understanding of the processes. (author)

  11. A Single Protein S-acyl Transferase Acts through Diverse Substrates to Determine Cryptococcal Morphology, Stress Tolerance, and Pathogenic Outcome.

    Directory of Open Access Journals (Sweden)

    Felipe H Santiago-Tirado

    2015-05-01

    Full Text Available Cryptococcus neoformans is an opportunistic yeast that kills over 625,000 people yearly through lethal meningitis. Host phagocytes serve as the first line of defense against this pathogen, but fungal engulfment and subsequent intracellular proliferation also correlate with poor patient outcome. Defining the interactions of this facultative intracellular pathogen with host phagocytes is key to understanding the latter's opposing roles in infection and how they contribute to fungal latency, dissemination, and virulence. We used high-content imaging and a human monocytic cell line to screen 1,201 fungal mutants for strains with altered host interactions and identified multiple genes that influence fungal adherence and phagocytosis. One of these genes was PFA4, which encodes a protein S-acyl transferase (PAT, one of a family of DHHC domain-containing proteins that catalyzes lipid modification of proteins. Deletion of PFA4 caused dramatic defects in cryptococcal morphology, stress tolerance, and virulence. Bioorthogonal palmitoylome-profiling identified Pfa4-specific protein substrates involved in cell wall synthesis, signal transduction, and membrane trafficking responsible for these phenotypic alterations. We demonstrate that a single PAT is responsible for the modification of a subset of proteins that are critical in cryptococcal pathogenesis. Since several of these palmitoylated substrates are conserved in other pathogenic fungi, protein palmitoylation represents a potential avenue for new antifungal therapeutics.

  12. Parallel versus Off-Pathway Michaelis-Menten Mechanism for Single-Enzyme Kinetics of a Fluctuating Enzyme.

    Science.gov (United States)

    Kumar, Ashutosh; Maity, Hiranmay; Dua, Arti

    2015-07-09

    Recent fluorescence spectroscopy measurements of the turnover time distribution of single-enzyme turnover kinetics of β-galactosidase provide evidence of Michaelis-Menten kinetics at low substrate concentration. However, at high substrate concentrations, the dimensionless variance of the turnover time distribution shows systematic deviations from the Michaelis-Menten prediction. This difference is attributed to conformational fluctuations in both the enzyme and the enzyme-substrate complex and to the possibility of both parallel- and off-pathway kinetics. Here, we use the chemical master equation to model the kinetics of a single fluctuating enzyme that can yield a product through either parallel- or off-pathway mechanisms. An exact expression is obtained for the turnover time distribution from which the mean turnover time and randomness parameters are calculated. The parallel- and off-pathway mechanisms yield strikingly different dependences of the mean turnover time and the randomness parameter on the substrate concentration. In the parallel mechanism, the distinct contributions of enzyme and enzyme-substrate fluctuations are clearly discerned from the variation of the randomness parameter with substrate concentration. From these general results, we conclude that an off-pathway mechanism, with substantial enzyme-substrate fluctuations, is needed to rationalize the experimental findings of single-enzyme turnover kinetics of β-galactosidase.

  13. Mechanical energy losses in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zelada, Griselda I. [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Lambri, Osvaldo Agustin [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Instituto de Fisica Rosario - CONICET, Member of the CONICET& #x27; s Research Staff, Avda. Pellegrini 250, 2000 Rosario (Argentina); Bozzano, Patricia B. [Laboratorio de Microscopia Electronica, Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499, 1650 San Martin (Argentina); Garcia, Jose Angel [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain)

    2012-10-15

    Mechanical spectroscopy (MS) and transmission electron microscopy (TEM) studies have been performed in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum, oriented for single slip, in order to study the dislocation dynamics in the temperature range within one third of the melting temperature. A damping peak related to the interaction of dislocation lines with both prismatic loops and tangles of dislocations was found. The peak temperature ranges between 900 and 1050 K, for an oscillating frequency of about 1 Hz. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. The effects of alloy purity on the mechanical behavior of soft oriented NiAl single crystals

    Science.gov (United States)

    Weaver, M. L.; Kaufman, M. J.; Noebe, R. D.

    1993-01-01

    Preliminary results of the effects of alloy purity on the mechanical properties of NiAl single crystals are presented. Two stoichiometric NiAl single crystals with different impurity contents were studied. It is concluded that reductions in the interstitial and substitutional levels cause reduced yield strengths in NiAl. Heat treatment also results in reduced yield and flow stresses in both CP-NiAl and Hp-NiAl which are considered to be due to a reduction in the concentration of thermal vacancies due to vacancy coalescence during heat treatment.

  15. Mechanism of DNA–binding loss upon single-point mutation in p53

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    Despite our current understanding of protein−DNA recognition, the mechanism(s) underlying the loss in protein−DNA binding affinity/ ... Keywords. p53 mutants; protein-DNA interactions; molecular dynamics simulations; free energy decomposition. Abbreviations ... of the salt–bridge with Asp 281, resulting in the loss of DNA.

  16. Studies of propane flame soot acting as heterogeneous ice nuclei in conjunction with single particle soot photometer measurements

    Directory of Open Access Journals (Sweden)

    I. Crawford

    2011-09-01

    Full Text Available The ice nucleation efficiency of propane flame soot particles with and without a sulphuric acid coating was investigated using the aerosol and cloud chamber facility AIDA (Aerosol Interaction and Dynamics in the Atmosphere. The test soot for cloud formation simulations was produced using a propane flame Combustion Aerosol Standard generator (CAST, Jing-CAST Technologies. The organic carbon content (OC of the test soot was altered in a reproducible fashion by changing the fuel/air mixture of the generator. The soot content of ice nuclei was subsequently investigated using a combination of a pumped counterflow virtual impactor (PCVI to separate and evaporate the ice crystals, and a DMT single particle soot photometer (SP2 to examine the mixing state of the BC containing ice residuals.

    Ice nucleation was found to be most efficient for uncoated soot of low organic carbon content (~5 % organic carbon content where deposition freezing occurred at an ice saturation ratio Sice ~ 1.22 at a temperature T = 226.6 K with 25 % of the test soot becoming active as ice nuclei. Propane flame soot of higher organic carbon content (~30 % and ~70 % organic carbon content showed significantly lower ice nucleation efficiency (an activated fraction of the order of a few percent in the experiments than the low organic carbon content soot, with water saturation being required for freezing to occur. Ice nucleation occurred over the range Sice = 1.22–1.70, and T = 223.2–226.6 K. Analysis of the SP2 data showed that the 5 % organic carbon content soot had an undetectable OC coating whereas the 30 % organic carbon content soot had a thicker or less volatile OC coating.

    The application of a sulphuric acid coating to the flame soot shifted the threshold of the onset of freezing towards that of the homogeneous freezing of sulphuric acid; for the minimum OC flame soot this inhibited nucleation since the

  17. Fluctuation mechanisms in superconductors nanowire single-photon counters, enabled by effective top-down manufacturing

    CERN Document Server

    Bartolf, Holger

    2016-01-01

    Holger Bartolf discusses state-of-the-art detection concepts based on superconducting nanotechnology as well as sophisticated analytical formulæ that model dissipative fluctuation-phenomena in superconducting nanowire single-photon detectors. Such knowledge is desirable for the development of advanced devices which are designed to possess an intrinsic robustness against vortex-fluctuations and it provides the perspective for honorable fundamental science in condensed matter physics. Especially the nanowire detector allows for ultra-low noise detection of signals with single-photon sensitivity and GHz repetition rates. Such devices have a huge potential for future technological impact and might enable unique applications (e.g. high rate interplanetary deep-space data links from Mars to Earth). Contents Superconducting Single-Photon Detectors Nanotechnological Manufacturing; Scale: 10 Nanometer Berezinskii-Kosterlitz Thouless (BKT) Transition, Edge-Barrier, Phase Slips Target Groups Researchers and students of...

  18. Mechanical and Electrical Properties of a Polyimide Film Significantly Enhanced by the Addition of Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Meador, Michael A.

    2005-01-01

    Single-wall carbon nanotubes have been shown to possess a combination of outstanding mechanical, electrical, and thermal properties. The use of carbon nanotubes as an additive to improve the mechanical properties of polymers and/or enhance their thermal and electrical conductivity has been a topic of intense interest. Nanotube-modified polymeric materials could find a variety of applications in NASA missions including large-area antennas, solar arrays, and solar sails; radiation shielding materials for vehicles, habitats, and extravehicular activity suits; and multifunctional materials for vehicle structures and habitats. Use of these revolutionary materials could reduce vehicle weight significantly and improve vehicle performance and capabilities.

  19. Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio

    Science.gov (United States)

    Wiesen, Bernard (Inventor)

    2008-01-01

    This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

  20. A Single-Molecule View of Genome Editing Proteins: Biophysical Mechanisms for TALEs and CRISPR/Cas9.

    Science.gov (United States)

    Cuculis, Luke; Schroeder, Charles M

    2017-06-07

    Exciting new advances in genome engineering have unlocked the potential to radically alter the treatment of human disease. In this review, we discuss the application of single-molecule techniques to uncover the mechanisms behind two premier classes of genome editing proteins: transcription activator-like effector nucleases (TALENs) and the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated system (Cas). These technologies have facilitated a striking number of gene editing applications in a variety of organisms; however, we are only beginning to understand the molecular mechanisms governing the DNA editing properties of these systems. Here, we discuss the DNA search and recognition process for TALEs and Cas9 that have been revealed by recent single-molecule experiments.

  1. Different quantization mechanisms in single-electron pumps driven by surface acoustic waves

    DEFF Research Database (Denmark)

    Utko, P.; Gloos, K.; Hansen, Jørn Bindslev

    2006-01-01

    We have studied the acoustoelectric current in single-electron pumps driven by surface acoustic waves. We have found that in certain parameter ranges two different sets of quantized steps dominate the acoustoelectric current versus gate-voltage characteristics. In some cases, both types of quanti......We have studied the acoustoelectric current in single-electron pumps driven by surface acoustic waves. We have found that in certain parameter ranges two different sets of quantized steps dominate the acoustoelectric current versus gate-voltage characteristics. In some cases, both types...

  2. A comparative study of microstructure and mechanical properties between friction stir welded single and double phase brass alloys

    Energy Technology Data Exchange (ETDEWEB)

    Heidarzadeh, A.; Saeid, T., E-mail: saeid@sut.ac.ir

    2016-01-01

    This study was done in order to compare the microstructure and mechanical properties of friction stir welded single and double phase brass alloys. The microstructure of the joints were examined using optical microscope, scanning electron microscope (SEM), scanning transmission electron microscope (STEM), and X-ray diffraction. Furthermore, tensile test and fractography were applied to evaluate the mechanical properties of the joints. The results showed that the grain size of the stir zone in the double phase joint was smaller than that of the single phase alloy. In comparison with base metals, both of the joints contained high density of dislocations with a qualitatively similar texture. However, the dislocation density of the double phase joint was somewhat lower than that of the single phase one. Moreover, the joints had higher tensile strength, lower elongation and less ductile fracture compared to their base metals due to their finer grain size and higher dislocation density. The double phase joint had higher strength and lower elongation than single phase joint due to the effect of the second phase.

  3. Fragmentation mechanisms based on single drop steam explosion experiments using flash X-ray radiography

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Frost, D.L.

    1994-01-01

    Flash X-ray and high-speed regular photography were used to investigate the fragmentation processes during the vapor explosion of single drops of molten metal immersed in water. For relatively low ambient flow velocities ( 45 m/s), vapor bubble growth is diminished and high-speed motion of vapor within the bubble leads to an enhanced fragmentation rate. (orig.)

  4. Single molecule charge transport : From a quantum mechanical to a classical description

    NARCIS (Netherlands)

    Kocherzhenko, A.A.; Grozema, F.C.; Siebbeles, L.D.A.

    2010-01-01

    This paper explores charge transport at the single molecule level. The conductive properties of both small organic molecules and conjugated polymers (molecular wires) are considered. In particular, the reasons for the transition from fully coherent to incoherent charge transport and the approaches

  5. Quantum Sensing of Mechanical Motion with a Single InAs Quantum Dot

    Science.gov (United States)

    2017-03-01

    manipulate s the entangle hanical racker1, Mi a E. Econo el Scheibn arch Laborat e Solutions, I at the Naval ysics, Virginia es...stal waveguide the membrane h resolution ed by sending cavity with a . , resolu single photo ...ability to as enhance the this platform . . . .

  6. Single shot damage mechanism of Mo/Si multilayer optics under intense pulsed XUV-exposures

    NARCIS (Netherlands)

    Khorsand, A.R.; Sobierajski, R.; Louis, Eric; Bruijn, S.; Gleeson, A.; van de Kruijs, Robbert Wilhelmus Elisabeth; Gullikson, E.M.; Bijkerk, Frederik

    2010-01-01

    We investigated single shot damage of Mo/Si multilayer coatings exposed to the intense fs XUV radiation at the Free-electron LASer facility in Hamburg - FLASH. The interaction process was studied in situ by XUV reflectometry, time resolved optical microscopy, and “post-mortem” by

  7. Mechanical properties of mammalian single smooth muscle cells. I. A low cost large range microforce transducer.

    NARCIS (Netherlands)

    J.J. Glerum (Jacobus); R. van Mastrigt (Ron)

    1990-01-01

    textabstractA transducer has been developed for measuring the minute forces generated during isometric contractions (1.0-10.0 microN) of single smooth muscle cells from the pig urinary bladder and the human uterus. In addition to its high sensitivity, resolution and stability (100 mV microN-1, and

  8. Exploring transduction mechanisms of protein transduction domains (PTDs) in living cells utilizing single-quantum dot tracking (SQT) technology.

    Science.gov (United States)

    Suzuki, Yasuhiro

    2012-01-01

    Specific protein domains known as protein transduction domains (PTDs) can permeate cell membranes and deliver proteins or bioactive materials into living cells. Various approaches have been applied for improving their transduction efficacy. It is, therefore, crucial to clarify the entry mechanisms and to identify the rate-limiting steps. Because of technical limitations for imaging PTD behavior on cells with conventional fluorescent-dyes, how PTDs enter the cells has been a topic of much debate. Utilizing quantum dots (QDs), we recently tracked the behavior of PTD that was derived from HIV-1 Tat (TatP) in living cells at the single-molecule level with 7-nm special precision. In this review article, we initially summarize the controversy on TatP entry mechanisms; thereafter, we will focus on our recent findings on single-TatP-QD tracking (SQT), to identify the major sequential steps of intracellular delivery in living cells and to discuss how SQT can easily provide direct information on TatP entry mechanisms. As a primer for SQT study, we also discuss the latest findings on single particle tracking of various molecules on the plasma membrane. Finally, we discuss the problems of QDs and the challenges for the future in utilizing currently available QD probes for SQT. In conclusion, direct identification of the rate-limiting steps of PTD entry with SQT should dramatically improve the methods for enhancing transduction efficiency.

  9. Exploring Transduction Mechanisms of Protein Transduction Domains (PTDs in Living Cells Utilizing Single-Quantum Dot Tracking (SQT Technology

    Directory of Open Access Journals (Sweden)

    Yasuhiro Suzuki

    2012-01-01

    Full Text Available Specific protein domains known as protein transduction domains (PTDs can permeate cell membranes and deliver proteins or bioactive materials into living cells. Various approaches have been applied for improving their transduction efficacy. It is, therefore, crucial to clarify the entry mechanisms and to identify the rate-limiting steps. Because of technical limitations for imaging PTD behavior on cells with conventional fluorescent-dyes, how PTDs enter the cells has been a topic of much debate. Utilizing quantum dots (QDs, we recently tracked the behavior of PTD that was derived from HIV-1 Tat (TatP in living cells at the single-molecule level with 7-nm special precision. In this review article, we initially summarize the controversy on TatP entry mechanisms; thereafter, we will focus on our recent findings on single-TatP-QD tracking (SQT, to identify the major sequential steps of intracellular delivery in living cells and to discuss how SQT can easily provide direct information on TatP entry mechanisms. As a primer for SQT study, we also discuss the latest findings on single particle tracking of various molecules on the plasma membrane. Finally, we discuss the problems of QDs and the challenges for the future in utilizing currently available QD probes for SQT. In conclusion, direct identification of the rate-limiting steps of PTD entry with SQT should dramatically improve the methods for enhancing transduction efficiency.

  10. Electrical trapping mechanism of single-microparticles in a pore sensor

    Directory of Open Access Journals (Sweden)

    Akihide Arima

    2016-11-01

    Full Text Available Nanopore sensing via resistive pulse technique are utilized as a potent tool to characterize physical and chemical property of single –molecules and –particles. In this article, we studied the influence of particle trajectory to the ionic conductance through a pore. We performed the optical/electrical simultaneous sensing of electrophoretic capture dynamics of single-particles at a pore using a microchannel/nanopore system. We detected ionic current drops synchronous to a fluorescently dyed particle being electrophoretically drawn and become immobilized at a pore in the optical imaging. We also identified anomalous trapping events wherein particles were captured at nanoscale pin-holes formed unintentionally in a SiN membrane that gave rise to relatively small current drops. This method is expected to be a useful platform for testing novel nanopore sensor design wherein current behaves in unpredictable manner.

  11. Investigation of Chirality Selection Mechanism of Single-Walled Carbon Nanotube

    Science.gov (United States)

    2015-07-17

    strong fibers [6, 7], membranes [8], and super - capacitor electrodes [9] have been proposed and demonstrated in a laboratory environment. However, the...Hatori, M. Yumura, and S. Iijima, “Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super ... capacitor electrodes,” Nature Mater. 5, 987 (2006). [10] Y. Li, D. Mann, M. Rolandi, W. Kim, A. Ural, S. Hung, A. Javey, J. Cao, D. Dunwei, E. Yenilmez

  12. Theoretical study of catalytic mechanism for single-site water oxidation process.

    Science.gov (United States)

    Lin, Xiangsong; Hu, Xiangqian; Concepcion, Javier J; Chen, Zuofeng; Liu, Shubin; Meyer, Thomas J; Yang, Weitao

    2012-09-25

    Water oxidation is a linchpin in solar fuels formation, and catalysis by single-site ruthenium complexes has generated significant interest in this area. Combining several theoretical tools, we have studied the entire catalytic cycle of water oxidation for a single-site catalyst starting with [Ru(II)(tpy)(bpm)(OH(2))](2+) (i.e., [Ru(II)-OH(2)](2+); tpy is 2,2':6',2''-terpyridine and bpm is 2,2'-bypyrimidine) as a representative example of a new class of single-site catalysts. The redox potentials and pK(a) calculations for the first two proton-coupled electron transfers (PCETs) from [Ru(II)-OH(2)](2+) to [Ru(IV) = O](2+) and the following electron-transfer process to [Ru(V) = O](3+) suggest that these processes can proceed readily in acidic or weakly basic conditions. The subsequent water splitting process involves two water molecules, [Ru(V) = O](3+) to generate [Ru(III)-OOH](2+), and H(3)O(+) with a low activation barrier (~10 kcal/mol). After the key O-O bond forming step in the single-site Ru catalysis, another PECT process oxidizes [Ru(III)-OOH](2+) to [Ru(IV)-OO](2+) when the pH is lower than 3.7. Two possible forms of [Ru(IV)-OO](2+), open and closed, can exist and interconvert with a low activation barrier (catalytic cycle. This understanding is helpful in the design of new catalysts for water oxidation.

  13. Mechanical signals in plant development: a new method for single cell studies

    Science.gov (United States)

    Lynch, T. M.; Lintilhac, P. M.

    1997-01-01

    Cell division, which is critical to plant development and morphology, requires the orchestration of hundreds of intracellular processes. In the end, however, cells must make critical decisions, based on a discrete set of mechanical signals such as stress, strain, and shear, to divide in such a way that they will survive the mechanical loads generated by turgor pressure and cell enlargement within the growing tissues. Here we report on a method whereby tobacco protoplasts swirled into a 1.5% agarose entrapment medium will survive and divide. The application of a controlled mechanical load to agarose blocks containing protoplasts orients the primary division plane of the embedded cells. Photoelastic analysis of the agarose entrapment medium can identify the lines of principal stress within the agarose, confirming the hypothesis that cells divide either parallel or perpendicular to the principal stress tensors. The coincidence between the orientation of the new division wall and the orientation of the principal stress tensors suggests that the perception of mechanical stress is a characteristic of individual plant cells. The ability of a cell to determine a shear-free orientation for a new partition wall may be related to the applied load through the deformation of the matrix material. In an isotropic matrix a uniaxial load will produce a rotationally symmetric strain field, which will define a shear-free plane. Where high stress intensities combine with the loading geometry to produce multiaxial loads there will be no axis of rotational symmetry and hence no shear free plane. This suggests that two mechanisms may be orienting the division plane, one a mechanism that works in rotationally symmetrical fields, yielding divisions perpendicular to the compressive tensor, parallel to the long axis of the cell, and one in asymmetric fields, yielding divisions parallel to the short axis of the cell and the compressive tensor.

  14. Structural, mechanical and light yield characterisation of heat treated LYSO:Ce single crystals for medical imaging applications

    CERN Document Server

    Mengucci, P; Auffray, E; Barucca, G; Cecchi, C; Chipaux, R; Cousson, A; Davì, F; Di Vara, N; Rinaldi, D; Santecchia, E

    2015-01-01

    Five single crystals of cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) grown by the Czochralski method were submitted to structural characterisation by X-ray (XRD) and neutron (ND) diffraction, scanning (SEM) and transmission (TEM) electron microscopy and energy dispersive microanalysis (EDS). The Ultimate Tensile Strength (UTS), the Young Modulus (YM) and the Light Yield (LY) of the samples were also measured in order to correlate the mechanical and the optical behaviour of the crystals with the characteristics of their microstructure. Two of the samples analysed were also heat treated at 300 °C for 10 h to evidence possible variations induced by the temperature in the optical and mechanical response of the crystals. Results showed that the mean compositional variations evidenced by the structural analyses do not affect the mechanical and optical behaviour of the samples. On the contrary, the thermal treatment could induce the formation of coherent spherical particles (size 10 to 15 nm), not unifo...

  15. Mechanical Stabilization of Martensite in Cu-Ni-Al Single Crystal and Unconventional Way to Detect It

    Science.gov (United States)

    Heczko, O.; Vronka, M.; Veřtát, P.; Rameš, M.; Onderková, K.; Kopecký, V.; Krátká, P.; Ge, Y.

    2018-03-01

    The microstructures and transformation behaviour of self-accommodated and mechanically stabilized martensite of Cu69.4Ni3.4Al27.2 (at.%) single crystal were investigated by optical microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetometry. XRD and TEM analyses showed the presence of both 2H and 18R phases in self-accommodated martensite. The mechanical compression of martensite (≈ 100 MPa) increased markedly the transformation temperature to austenite, i.e. resulting in significant mechanical stabilization of martensite. The 18R phase disappeared after the compression. This reveals the important role of 18R phase in transformation behaviour of Cu-Ni-Al alloy. Furthermore, we demonstrate that thermo-magnetic measurement is suitable method to analyse the martensitic transformation even for diamagnetic material.

  16. The Effects of Mechanical and Thermal Stimuli on Local Field Potentials and Single Unit Activity in Parkinson's Disease Patients.

    Science.gov (United States)

    Belasen, Abigail; Youn, Youngwon; Gee, Lucy; Prusik, Julia; Lai, Brant; Ramirez-Zamora, Adolfo; Rizvi, Khizer; Yeung, Philip; Shin, Damian S; Argoff, Charles; Pilitsis, Julie G

    2016-10-01

    Chronic pain is a major, debilitating symptom of Parkinson's disease (PD). Although, deep brain stimulation (DBS) has been shown to improve pain outcomes, the mechanisms underlying this phenomenon are unclear. Microelectrode recording allows us to measure both local field potentials (LFPs) and single neuronal unit activity (SUA). In this study, we examined how single unit and LFP oscillatory activity in the basal ganglia are impacted by mechanical and thermal sensory stimuli and explored their role in pain modulation. We assessed changes in LFPs and SUAs in the subthalamic nucleus (STN), globus pallidus interna (Gpi), and globus pallidus externa (Gpe) following exposure with mechanical or thermal stimuli. Sensory thresholds were determined pre-operatively using quantitative sensory testing. Based on these data, patients were exposed to innocuous and noxious mechanical, pressure, and thermal stimuli at individualized thresholds. In the STN, LFP alpha oscillatory activity and SUA increased in response to innocuous mechanical stimuli; SUA further increased in response to noxious mechanical, noxious pressure, and noxious thermal stimuli (p thermal stimuli; SUA also increased in response to innocuous thermal stimuli (p thermal stimuli increased LFP gammaactivity; noxious pressure stimuli decreased low betaactivity; SUA increased in response to noxious thermal stimuli (p thermal stimuli alter basal ganglia LFPs and SUAs in PD. While STN SUA increases nearly uniformly to all sensory stimuli, SUA in the pallidal nuclei respond solely to thermal stimuli. Similarly, thermal stimuli yield increases in pallidal LFP activity, but not STN activity. We speculate that DBS may provide analgesia through suppression of stimuli-specific changes in basal ganglia activity, supporting a role for these nuclei in sensory and pain processing circuits. © 2016 International Neuromodulation Society.

  17. Mechanical properties of cocoons constructed consecutively by a single silkworm caterpillar, Bombyx mori

    Science.gov (United States)

    Huang, S. Q.; Zhao, H. P.; Feng, X. Q.; Cui, W.; Lin, Z.; Xu, M. Q.

    2008-04-01

    Most animals have the ability to adapt, to some extends and in different ways, the variation or disturbance of environment. In our experiments, we forced a silkworm caterpillar to spin two, three or four thin cocoons by taking it out from the cocoon being constructed. The mechanical properties of these cocoons were studied by static tensile tests and dynamic mechanical thermal analysis. Though external disturbances may cause the decrease in the total weight of silk spun by the silkworm, a gradual enhancement was interestingly found in the mechanical properties of these thin cocoons. Scanning electron microscopy observations of the fractured specimens of the cocoons showed that there exist several different energy dissipation mechanisms occurred simultaneously at macro-, meso-, and micro-scales, yielding a superior capacity of cocoons to adsorb the energy of possible attacks from the outside and to protect efficiently its pupa against damage. Through evolution of millions of years, therefore, the silkworm Bombyx mori seems to have gained the ability to adapt external disturbances and to redesign a new cocoon with optimized protective function when its first cocoon has been damaged for some reasons.

  18. Single Molecular Detection via Micro-Scale Polymeric Opto-Electro-Mechanical Systems

    Science.gov (United States)

    2005-06-01

    5.1.1.1.2 Mechanical Characteristics The dynamics of the bottom Y microlens scanner were characterized with a Microvision Stroboscopic Motion...Hong, "Multidimensional motion analysis of MEMS using computer microvision ," Proc. IEEE Solid-State Sensor and Actuator Workshop, 150-155 (1998

  19. Insulator-protected mechanically controlled break junctions for measuring single-molecule conductance in aqueous environments

    NARCIS (Netherlands)

    Muthusubramanian, N.; Galan, E.; Maity, C.; Eelkema, R.; Grozema, F.C.; van der Zant, H.S.J.

    2016-01-01

    We present a method to fabricate insulated gold mechanically controlled break junctions (MCBJ) by coating the metal with a thin layer of aluminum oxide using plasma enhanced atomic layer deposition. The Al2O3 thickness deposited on the MCBJ devices was varied from 2 to 15 nm

  20. Acute effects of single and multiple level thoracic manipulations on chronic mechanical neck pain: a randomized controlled trial

    Science.gov (United States)

    Puntumetakul, Rungthip; Suvarnnato, Thavatchai; Werasirirat, Phurichaya; Uthaikhup, Sureeporn; Yamauchi, Junichiro; Boucaut, Rose

    2015-01-01

    Background Thoracic spine manipulation has become a popular alternative to local cervical manipulative therapy for mechanical neck pain. This study investigated the acute effects of single-level and multiple-level thoracic manipulations on chronic mechanical neck pain (CMNP). Methods Forty-eight patients with CMNP were randomly allocated to single-level thoracic manipulation (STM) at T6–T7 or multiple-level thoracic manipulation (MTM), or to a control group (prone lying). Cervical range of motion (CROM), visual analog scale (VAS), and the Thai version of the Neck Disability Index (NDI-TH) scores were measured at baseline, and at 24-hour and at 1-week follow-up. Results At 24-hour and 1-week follow-up, neck disability and pain levels were significantly (Pneck disability, pain level at rest, and CROM between the STM and MTM groups. Conclusion These results suggest that both single-level and multiple-level thoracic manipulation improve neck disability, pain levels, and CROM at 24-hour and 1-week follow-up in patients with CMNP. PMID:25624764

  1. Growth Mechanism of Single-Walled Carbon Nanotubes on Iron–Copper Catalyst and Chirality Studies by Electron Diffraction

    DEFF Research Database (Denmark)

    He, Maoshuai; Liu, Bilu; Chernov, Alexander I.

    2012-01-01

    Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type....... by impregnation, showing similar catalytic performance as the atomic layer deposition-prepared catalyst, yielding single-walled carbon nanotubes with a similar narrow chirality distribution.......Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type....... The growth mechanisms as well as the roles of different components in the catalyst were studied in situ using environmental transmission electron microscopy and infrared spectroscopy. On the basis of the understanding of carbon nanotube growth mechanisms, an MgO-supported FeCu catalyst was prepared...

  2. Assessment of the Pharmacokinetics, Pharmacodynamics, and Safety of Single Doses of TV-1106, a Long-Acting Growth Hormone, in Healthy Japanese and Caucasian Subjects.

    Science.gov (United States)

    Cohen-Barak, Orit; Barkay, Hadas; Rasamoelisolo, Michele; Butler, Kathleen; Yamada, Kazumasa; Bassan, Merav; Yoon, Esther; Spiegelstein, Ofer

    2017-07-01

    TV-1106 is a human serum albumin genetically fused to recombinant human growth hormone, designed to provide a long-acting alternative to daily growth hormone (GH) injections in patients with GH deficiency. This study investigated the pharmacokinetics, pharmacodynamics, and safety of single subcutaneous doses of TV-1106 (7.5, 15, 50, and 100 mg) in Japanese (n = 44) and caucasian (n = 44) healthy subjects. TV-1106 pharmacokinetics and pharmacodynamics were comparable in Japanese and caucasian populations. TV-1106 demonstrated relatively slow absorption (median t max , 10-30 hours) and a mean elimination half-life of 26-36 hours. Apparent clearance and volume of distribution decreased with increasing TV-1106 doses in both populations and appeared to increase more than dose proportionality across the tested doses. Insulin-like growth factor-1 (IGF-1) and IGF binding protein-3 (IGFBP-3) increased in a dose-related manner, with maximum responses observed at 33-96 and 42-109 hours, respectively. IGF-1 and IGFBP-3 returned to baseline values at 168 hours following 7.5 and 15 mg of TV-1106, and 336 hours following 50 and 100 mg of TV-1106. TV-1106 appeared safe in both populations. There was no evidence of differences in pharmacokinetics, pharmacodynamics, or safety of TV-1106 between Japanese and caucasian populations. The data also demonstrate long-acting growth hormone properties of TV-1106 and support its potential for once-weekly dosing. © 2016, The Authors. Clinical Pharmacology in Drug Development Published by Wiley Periodicals, Inc. on behalf of The American College of Clinical Pharmacology.

  3. Environmental effects on deformation mechanism and dislocation microstructure in fatigued copper single crystal

    International Nuclear Information System (INIS)

    Yang, J.H.; Zhang, X.P.; Mai, Y.-W.; Jia, W.P.; Ke, W.

    2005-01-01

    The deformation and dislocation microstructure of a [0 1 3] double-slip-oriented copper single crystal under a symmetric tension-compression cyclic load were characterized at room temperature in open-air and a neutral 0.5 M NaCl aqueous solution, respectively. The surface morphology of deformed specimens and the dislocation structures at saturation stage of cyclic deformation were observed using scanning electron microscopy (SEM) by the electron channeling contrast (ECC) technique and transmission electron microscopy (TEM). The results show that the saturation dislocation structures during the corrosion fatigue in the 0.5 M NaCl aqueous solution mainly consist of labyrinth, wall and vein dislocation microstructures, as well as deformation twins, which differ from the wall and vein dislocation structures in open-air environment. More importantly, here we report TEM observations that provide evidence of deformation twinning in the [0 1 3] double-slip-oriented copper single crystal during corrosion fatigue at room temperature and a very slow strain rate, which was generally only observed at sub-ambient temperature and/or high strain rate conditions

  4. Promoters Architecture-Based Mechanism for Noise-Induced Oscillations in a Single-Gene Circuit.

    Science.gov (United States)

    Guisoni, N; Monteoliva, D; Diambra, L

    2016-01-01

    It is well known that single-gene circuits with negative feedback loop can lead to oscillatory gene expression when they operate with time delay. In order to generate these oscillations many processes can contribute to properly timing such delay. Here we show that the time delay coming from the transitions between internal states of the cis-regulatory system (CRS) can drive sustained oscillations in an auto-repressive single-gene circuit operating in a small volume like a cell. We found that the cooperative binding of repressor molecules is not mandatory for a oscillatory behavior if there are enough binding sites in the CRS. These oscillations depend on an adequate balance between the CRS kinetic, and the synthesis/degradation rates of repressor molecules. This finding suggest that the multi-site CRS architecture can play a key role for oscillatory behavior of gene expression. Finally, our results can also help to synthetic biologists on the design of the promoters architecture for new genetic oscillatory circuits.

  5. Single Particle Tracking to Characterize the Mechanism of Pore Formation by Pore Forming Proteins

    OpenAIRE

    Subburaj, Yamunadevi

    2014-01-01

    Pore formation is a common natural mechanism occurring in large number of organisms where proteins are involved as toxins, effectors in immune response or apoptosis. Despite intense research, the structural and dynamic aspects of oligomerization and membrane permeabilization by pore forming proteins remains poorly understood. In this work we have aimed to provide a better understanding on dynamics, oligomerization and pore forming process of two proteins; a) Equinatoxin II, b) Bax (Bcl2 famil...

  6. Electric-field-tunable mechanical properties of relaxor ferroelectric single crystal measured by nanoindentation

    OpenAIRE

    Zhou, Hao; Pei, Yongmao; Li, Faxin; Luo, Haosu; Fang, Daining

    2014-01-01

    Electric field dependent mechanical properties of relaxor ferroelectric material Pb(Mn1/3Nb2/3)O3-PbTiO3 are investigated with the nanoindentation technique. Giant electric-field-tunable apparent elastic modulus (up to -39%), hardness (-9% to 20%) and energy dissipation (up to -13%) are reported. Based on experimental data, a characterization method of electromechanical coupled nanoindentation is proposed. In this method, an electric field tunable scaling relationship among elastic modulus, h...

  7. Experimental studies of the dynamic mechanical response of a single polymer chain

    DEFF Research Database (Denmark)

    Thormann, Esben; Evans, Drew R.; Craig, Vincent S. J.

    2006-01-01

    mechanical response from poly(vinyl alcohol) does not differ from its static response. This result is not unexpected as poly(vinyl alcohol) is a highly flexible polymer with intramolecular relaxation processes taking place on a short time scale. The choice of a polymer with a fast relaxation allows its...... static properties to be recovered from the dynamic measurements and enables the method suggested in this paper for decoupling the polymer response from the hydrodynamic response to be validated....

  8. Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. 1 and 2

    International Nuclear Information System (INIS)

    Brieger, M.

    2004-01-01

    The established statistical interpretation of quantum mechanics never envisioned our today's ability to handle and investigate single particles in trap devices. After scrutinizing the development of quantum mechanics, we point out that Schroedinger's equation establishes an energy representation, which obtains the energy eigenvalues as extrema of the energy curve or on the energy hypersurface, respectively. We also strongly emphasize its never exhausted capability of accounting in classical terms and full detail for the dynamics of single particles in closed systems. This is demonstrated for several familiar examples. They show that the eigensolutions to Schroedinger's equation must not blindly be identified with physically stationary states. The gained insight into the true dynamics allows to describe, without involving QED, the time evolution of a complete spontaneous transition as being driven by unbalanced internal dynamics. This mechanism relies on the fact that perfect balances are only possible in the exact extrema of the total energy and that any deviation, which is characterized by nonstationary states, makes multipole moments oscillate and emit electromagnetic radiation. (orig.)

  9. Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Brieger, M. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Technische Physik

    2004-07-01

    The established statistical interpretation of quantum mechanics never envisioned our today's ability to handle and investigate single particles in trap devices. After scrutinizing the development of quantum mechanics, we point out that Schroedinger's equation establishes an energy representation, which obtains the energy eigenvalues as extrema of the energy curve or on the energy hypersurface, respectively. We also strongly emphasize its never exhausted capability of accounting in classical terms and full detail for the dynamics of single particles in closed systems. This is demonstrated for several familiar examples. They show that the eigensolutions to Schroedinger's equation must not blindly be identified with physically stationary states. The gained insight into the true dynamics allows to describe, without involving QED, the time evolution of a complete spontaneous transition as being driven by unbalanced internal dynamics. This mechanism relies on the fact that perfect balances are only possible in the exact extrema of the total energy and that any deviation, which is characterized by nonstationary states, makes multipole moments oscillate and emit electromagnetic radiation. (orig.)

  10. Crystal growth, structural, thermal and mechanical behavior of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals

    Science.gov (United States)

    Mahadevan, M.; Ramachandran, K.; Anandan, P.; Arivanandhan, M.; Bhagavannarayana, G.; Hayakawa, Y.

    2014-12-01

    Single crystals of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of L-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method.

  11. Mechanical stability of a locked step-plate versus single compression screw fixation for medial displacement calcaneal osteotomy.

    Science.gov (United States)

    Konan, Sujith; Meswania, Jay; Blunn, Gordon W; Madhav, Rohit T; Oddy, Michael J

    2012-08-01

    Reconstruction of a flatfoot commonly involves a calcaneal Medial Displacement Osteotomy (MDO) to correct hindfoot valgus in combination with soft tissue procedures. We compared fixation of an MDO using either a single, large cannulated screw versus a locking step-plate in load to failure in a cadaveric model. Eight matched pairs of cadaveric limbs were loaded using a mechanical testing rig. Two pairs served as non-operated controls. The remaining paired limbs underwent a 10-mm MDO stabilized either with a single 7-mm screw or a step-plate with four locking screws. One pair was used as a pilot study and the remaining five pairs were loaded up to 4500 N to failure. In the five pairs loaded to failure, the median (with 95% CI) maximum force were 1779 N (1099-2312) and 826 N (288-1607) for the plate and screw, respectively (p = 0.043). With single screw fixation, the tuberosity fragment consistently failed by rotation and angulation into varus. With plate fixation, failure occurred as the screws cut through the internal surfaces of the tuberosity and body with no failure at the screw-plate interface. In this cadaveric model, a locked step-plate supported a significantly higher maximum force than a single large cannulated screw. The magnitude of the load supported by the locking step-plate suggests that allowing early weightbearing post-operation may be safe in clinical practice before union of the osteotomy.

  12. Influence of composition on the microstructure and mechanical properties of a nickel-base superalloy single crystal

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1984-01-01

    The effects of cobalt, tantalum, and tungsten contents on the microstructure and mechanical properties of single crystal Mar-M247 were investigated. Elevated temperature tensile and creep-rupture properties of 001 oriented single crystals were related to microstructural features of the alloys. Substitution of Ni for Co in the high refractory metal alloys increased the lattice mismatch, which was considered to be the cause of the increases in tensile and creep strength. Substitution of Ni for Ta caused large decreases in tensile strength and creep life, consistent with decreases in gamma prime volume fraction, lattice mismatch, and solid solution hardening. Substitution of W for Ta resulted in decreased life at high stresses, which was related to small decreases in mismatch and volume fraction. However, the W substitution resulted in improved life at low stresses, which was related to solid solution strengthening by W.

  13. Effects of low temperature neutron irradiation on the mechanical properties of iron single crystals

    International Nuclear Information System (INIS)

    Kitajima, K.; Abe, H.; Takamura, S.; Okuda, S.

    1975-01-01

    Measurements were made on tensile properties and their recovery characteristics of single crystals of pure iron and iron containing carbon of 4 to 60 ppm irradiated in reactor to the dose of 3 x 10 16 to approximately 3 x 10 17 nvt (greater than 0.1 MeV) at approximately 5 0 K. The yield stress showed large softening at less than or equal to 90 0 K saturating to a value nearly independent of orientations for greater than or equal to 1 x 10 17 nvt. The softening recovered and hardening set in at several temperature stages. The activation energies of the recovery and the activation parameters of plastic deformations at various annealing stages were determined. Carbon suppressed the softening and its recovery but much enhanced the hardening at the stage of 300 to approximately 400 0 K

  14. Effect of grain defects on the mechanical behavior of nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Haibin; Guo, Haiding [Nanjing Univ. of Aeronautics and Astronautics (China). Jiangsu Province Key Lab. of Aerospace Power System

    2017-03-15

    In this paper, a single crystal (SC) partition model, consisting of primary grains and grain defects, is proposed to simulate the weakening effect of grain defects generated at geometric discontinuities of SC materials. The plastic deformation of SC superalloy is described with the modified yield criterion, associated flow rule and hardening law. Then a bicrystal model containing only one group of misoriented grains under uniaxial loading is constructed and analyzed in the commercial finite element software ABAQUS. The simulation results indicate that the yield strength and elastic modulus of misoriented grains, which are determined by the crystallographic orientation, have a significant effect on the stress distribution of the bicrystal model. A critical stress, which is calculated by the stress state at critical regions, is proposed to evaluate the local stress rise at the sub-boundary of primary and misoriented grains.

  15. Electronic properties of dislocations introduced mechanically at room temperature on a single crystal silicon surface

    International Nuclear Information System (INIS)

    Ogawa, Masatoshi; Kamiya, Shoji; Izumi, Hayato; Tokuda, Yutaka

    2012-01-01

    This paper focuses on the effects of temperature and environment on the electronic properties of dislocations in n-type single crystal silicon near the surface. Deep level transient spectroscopy (DLTS) analyses were carried out with Schottky electrodes and p + -n junctions. The trap level, originally found at E C -0.50 eV (as commonly reported), shifted to a shallower level at E C -0.23 eV after a heat treatment at 350 K in an inert environment. The same heat treatment in lab air, however, did not cause any shift. The trap level shifted by the heat treatment in an inert environment was found to revert back to the original level when the specimens were exposed to lab air again. Therefore, the intrinsic trap level is expected to occur at E C -0.23 eV and shift sensitively with gas adsorption in air.

  16. PEDIATRIC HEAD INJURIES, MECHANISM TO MANAGEMENT: EXPERIENCE OF A SINGLE CENTER

    Directory of Open Access Journals (Sweden)

    Pankaj

    2016-01-01

    Full Text Available INTRODUCTION Head injury is very common in modern life. Patients of any age group may have head injury however mechanism of head injury, pathophysiology and outcome of head injury is quite different in adults as compared to children. Road traffic accident is a common mode of head injury in adults while fall from height and household abuse is common mode in children. In Western countries, there is a separate registry system for pediatric head injury but there is no such system exist in india. Our present study is focused on pediatric head injury and evaluation of factors that affect the final outcome in pediatric patients.

  17. Change-over natural and mechanical ventilation system energy consumption in single-family buildings

    Science.gov (United States)

    Kostka, Maria; Szulgowska-Zgrzywa, Małgorzata

    2017-11-01

    The parameters of the outside air in Poland cause that in winter it is reasonable to use a mechanical ventilation equipped with a heat recovery exchanger. The time of spring, autumn, summer evenings and nights are often characterized by the parameters of the air, which allow for a natural ventilation and reduce the electricity consumption. The article presents the possibilities of energy consumption reduction for three energy standards of buildings located in Poland, ventilated by a change-over hybrid system. The analysis was prepared on the assumption that the air-to-water heat pump is the heat source for the buildings.

  18. Fetal Tendinous Connection Between the Tensor Tympani and Tensor Veli Palatini Muscles: A Single Digastric Muscle Acting for Morphogenesis of the Cranial Base.

    Science.gov (United States)

    Rodríguez-Vázquez, José Francisco; Sakiyama, Koji; Abe, Hiroshi; Amano, Osamu; Murakami, Gen

    2016-04-01

    Some researchers contend that in adults the tensor tympani muscle (TT) connects with the tensor veli palatini muscle (TVP) by an intermediate tendon, in disagreement with the other researchers. To resolve this controversy, we examined serial sections of 50 human embryos and fetuses at 6-17 weeks of development. At 6 weeks, in the first pharyngeal arch, a mesenchymal connection was found first to divide a single anlage into the TT and TVP. At and after 7 weeks, the TT was connected continuously with the TVP by a definite tendinous tissue mediolaterally crossing the pharyngotympanic tube. At 11 weeks another fascia was visible covering the cranial and lateral sides of the tube. This "gonial fascia" had two thickened borders: the superior one corresponded to a part of the connecting tendon between the TT and TVP; the inferior one was a fibrous band ending at the os goniale near the lateral end of the TVP. In association with the gonial fascia, the fetal TT and TVP seemed to provide a functional complex. The TT-TVP complex might first help elevate the palatal shelves in association with the developing tongue. Next, the tubal passage, maintained by contraction of the muscle complex, seems to facilitate the removal of loose mesenchymal tissues from the tympanic cavity. Third, the muscle complex most likely determined the final morphology of the pterygoid process. Consequently, despite the controversial morphologies in adults, the TT and TVP seemed to make a single digastric muscle acting for the morphogenesis of the cranial base. © 2016 Wiley Periodicals, Inc.

  19. Mechanical unfolding of proteins: reduction to a single-reaction coordinate unfolding potential, and an application of the Jarzynski Relation

    Science.gov (United States)

    Olmsted, Peter; West, Daniel; Paci, Emanuele

    2007-03-01

    Single molecule force spectroscopy (AFM, optical tweezers, etc) has revolutionized the study of many biopolymers, including DNA, RNA, and proteins. In this talk I will discuss recent work on modelling of mechanical unfolding of proteins, as often probed by AFM. I will address two issues in obtaining a coarse-grained description of protein unfolding: how to project the entire energy landscape onto an effective one dimensional unfolding potential, and how to apply the Jarzynski Relation to extract equilibrium free energies from nonequilibrium unfolding experiments.

  20. Lifetimes of organic photovoltaics: Design and synthesis of single oligomer molecules in order to study chemical degradation mechanisms

    DEFF Research Database (Denmark)

    Alstrup, J.; Norrman, K.; Jørgensen, M.

    2006-01-01

    Degradation mechanisms in organic and polymer photovoltaics are addressed through the study of an organic photovoltaic molecule based on a single phenylene-vinylene-type oligomer molecule. The synthesis of such a model compound with different end-groups is presented that allows for assignment...... of degradation products from different parts of the molecule. Photovoltaic devices with and without C(60) have been prepared and their characteristics under AM1.5 conditions are reported. The degradation of the active phenylene-vinylene compound in darkness and after 20h of illumination were investigated using...

  1. Organization of DNA partners and strand exchange mechanisms during Flp site-specific recombination analyzed by difference topology, single molecule FRET and single molecule TPM.

    Science.gov (United States)

    Ma, Chien-Hui; Liu, Yen-Ting; Savva, Christos G; Rowley, Paul A; Cannon, Brian; Fan, Hsiu-Fang; Russell, Rick; Holzenburg, Andreas; Jayaram, Makkuni

    2014-02-20

    Flp site-specific recombination between two target sites (FRTs) harboring non-homology within the strand exchange region does not yield stable recombinant products. In negatively supercoiled plasmids containing head-to-tail sites, the reaction produces a series of knots with odd-numbered crossings. When the sites are in head-to-head orientation, the knot products contain even-numbered crossings. Both types of knots retain parental DNA configuration. By carrying out Flp recombination after first assembling the topologically well defined Tn3 resolvase synapse, it is possible to determine whether these knots arise by a processive or a dissociative mechanism. The nearly exclusive products from head-to-head and head-to-tail oriented "non-homologous" FRT partners are a 4-noded knot and a 5-noded knot, respectively. The corresponding products from a pair of native (homologous) FRT sites are a 3-noded knot and a 4-noded catenane, respectively. These results are consistent with non-homology-induced two rounds of dissociative recombination by Flp, the first to generate reciprocal recombinants containing non-complementary base pairs and the second to produce parental molecules with restored base pairing. Single molecule fluorescence resonance energy transfer (smFRET) analysis of geometrically restricted FRTs, together with single molecule tethered particle motion (smTPM) assays of unconstrained FRTs, suggests that the sites are preferentially synapsed in an anti-parallel fashion. This selectivity in synapse geometry occurs prior to the chemical steps of recombination, signifying early commitment to a productive reaction path. The cumulative topological, smFRET and smTPM results have implications for the relative orientation of DNA partners and the directionality of strand exchange during recombination mediated by tyrosine site-specific recombinases. Copyright © 2013. Published by Elsevier Ltd.

  2. Internal mechanical stresses and the thermodynamic and adhesion parameters of the metal condensate-single-crystal silicon system

    Science.gov (United States)

    Coman, B. P.; Juzevych, V. N.

    2012-07-01

    The kinetics of generation of internal mechanical stresses σ( d) in chromium, copper, gold, and aluminum thin films on single-crystal silicon substrates at different deposition rates has been experimentally investigated using the cantilever method. A two-step character of the variations in internal tensile stresses has been revealed. The regularities of the formation of the maximum level of mechanical stresses in the condensates under investigation have been established. The energy and adhesion parameters of chromium, copper, gold, and aluminum nanolayers on silicon, germanium, and nickel substrates have been studied using the macroscopic methods of surface physics. The interfacial energy, interfacial tension, work of adhesion, interfacial charge, and a new energy characteristic of the interfacial layer, namely, the energy of adhesive bonds, which exceeds the interfacial energy, have been determined.

  3. Emergence of azole resistance in Aspergillus fumigatus and spread of a single resistance mechanism.

    Directory of Open Access Journals (Sweden)

    Eveline Snelders

    2008-11-01

    Full Text Available BACKGROUND: Resistance to triazoles was recently reported in Aspergillus fumigatus isolates cultured from patients with invasive aspergillosis. The prevalence of azole resistance in A. fumigatus is unknown. We investigated the prevalence and spread of azole resistance using our culture collection that contained A. fumigatus isolates collected between 1994 and 2007. METHODS AND FINDINGS: We investigated the prevalence of itraconazole (ITZ resistance in 1,912 clinical A. fumigatus isolates collected from 1,219 patients in our University Medical Centre over a 14-y period. The spread of resistance was investigated by analyzing 147 A. fumigatus isolates from 101 patients, from 28 other medical centres in The Netherlands and 317 isolates from six other countries. The isolates were characterized using phenotypic and molecular methods. The electronic patient files were used to determine the underlying conditions of the patients and the presence of invasive aspergillosis. ITZ-resistant isolates were found in 32 of 1,219 patients. All cases were observed after 1999 with an annual prevalence of 1.7% to 6%. The ITZ-resistant isolates also showed elevated minimum inhibitory concentrations of voriconazole, ravuconazole, and posaconazole. A substitution of leucine 98 for histidine in the cyp51A gene, together with two copies of a 34-bp sequence in tandem in the gene promoter (TR/L98H, was found to be the dominant resistance mechanism. Microsatellite analysis indicated that the ITZ-resistant isolates were genetically distinct but clustered. The ITZ-sensitive isolates were not more likely to be responsible for invasive aspergillosis than the ITZ-resistant isolates. ITZ resistance was found in isolates from 13 patients (12.8% from nine other medical centres in The Netherlands, of which 69% harboured the TR/L98H substitution, and in six isolates originating from four other countries. CONCLUSIONS: Azole resistance has emerged in A. fumigatus and might be more

  4. Comparison of the Local Tolerability to 5 Long-acting Drug Nanosuspensions with Different Stabilizing Excipients, Following a Single Intramuscular Administration in the Rat.

    Science.gov (United States)

    Chamanza, Ronnie; Darville, Nicolas; van Heerden, Marjolein; De Jonghe, Sandra

    2018-01-01

    To investigate the effects of common nanosuspension-stabilizing excipients on the nature and temporal evolution of histopathological changes at intramuscular (i.m.) administration sites, 5 groups of 39 male rats per group received a single injection of 1 of the 5 analogous crystalline drug nanosuspensions containing 200 mg/ml of an antiviral compound with particle sizes of ±200 nm and identical vehicle compositions, except for the type of nanosuspension stabilizer. The investigated stabilizers were poloxamer 338, poloxamer 407, d-α-tocopherol polyethylene glycol 1,000-succinate (TPGS), polysorbate 80, and polysorbate 80 combined with egg phosphatidylglycerol. Histopathology and immunohistochemistry revealed progressive inflammatory changes at the i.m. administration sites and the draining lymph nodes that differed according to the time point of sacrifice and the type of stabilizer. Although the overall time course of inflammatory changes was similar across the groups, differences in the nature, severity, and timing of the inflammatory response were observed between animals injected with poloxamer- or TPGS-containing nanosuspensions and those injected with formulations containing polysorbate 80. A more severe and prolonged active inflammatory phase, the presence of multinucleate giant cells, prolonged macrophage infiltration of the formulation depot, and more persistent histiocytic infiltrates in the lymph nodes were observed in the polysorbate 80-containing nanosuspension groups. Such vehicle-mediated effects could influence the overall tolerability profile of long-acting nanosuspensions.

  5. Electric-field-tunable mechanical properties of relaxor ferroelectric single crystal measured by nanoindentation

    Science.gov (United States)

    Zhou, Hao; Pei, Yongmao; Li, Faxin; Luo, Haosu; Fang, Daining

    2014-02-01

    Electric field dependent mechanical properties of relaxor ferroelectric material Pb(Mn1/3Nb2/3)O3-PbTiO3 are investigated with the nanoindentation technique. Giant electric-field-tunable apparent elastic modulus (up to -39%), hardness (-9% to 20%), and energy dissipation (up to -13%) are reported. Based on experimental data, a characterization method of electromechanical coupled nanoindentation is proposed. In this method, an electric field tunable scaling relationship among elastic modulus, hardness, and indentation work for ferroelectric materials can be determined. In addition, this method can be used to obtain the electric-field-dependent elastic modulus and hardness, and avoid the estimate of contact area in the Oliver-Pharr method. Finally, the different effects on elastic modulus between positive and negative electric fields can be explained by the flexoelectric effect.

  6. Fragmentation mechanisms based on single drop steam explosion experiments using flash X-ray radiography

    Energy Technology Data Exchange (ETDEWEB)

    Ciccarelli, G. (Brookhaven National Lab., Dept. of Advanced Technology, Upton, NY (United States)); Frost, D.L. (Mechanical Engineering Dept., McGill Univ., Montreal, PQ (Canada))

    1994-02-01

    Flash X-ray and high-speed regular photography were used to investigate the fragmentation processes during the vapor explosion of single drops of molten metal immersed in water. For relatively low ambient flow velocities (<5 m/s), a comparison of the breakup of hot and cold drops shows that whereas cold drops breakup due to the stripping of fragments by the relative flow, the fragmentation of a hot drop is dominated by the growth and collapse of a vapor bubble. X-ray radiographs show during the growth of the bubble, that fine filaments of metal protrude from the drop and the drop surface becomes highly convoluted. Using a simple model for the bubble dynamics, an estimate of the energy budget shows that the majority (about 80%) of the thermal energy transfer occurs during bubble collapse. For hot drops at higher flow velocities (>45 m/s), vapor bubble growth is diminished and high-speed motion of vapor within the bubble leads to an enhanced fragmentation rate. (orig.)

  7. Efficient single-pixel multispectral imaging via non-mechanical spatio-spectral modulation.

    Science.gov (United States)

    Li, Ziwei; Suo, Jinli; Hu, Xuemei; Deng, Chao; Fan, Jingtao; Dai, Qionghai

    2017-01-27

    Combining spectral imaging with compressive sensing (CS) enables efficient data acquisition by fully utilizing the intrinsic redundancies in natural images. Current compressive multispectral imagers, which are mostly based on array sensors (e.g, CCD or CMOS), suffer from limited spectral range and relatively low photon efficiency. To address these issues, this paper reports a multispectral imaging scheme with a single-pixel detector. Inspired by the spatial resolution redundancy of current spatial light modulators (SLMs) relative to the target reconstruction, we design an all-optical spectral splitting device to spatially split the light emitted from the object into several counterparts with different spectrums. Separated spectral channels are spatially modulated simultaneously with individual codes by an SLM. This no-moving-part modulation ensures a stable and fast system, and the spatial multiplexing ensures an efficient acquisition. A proof-of-concept setup is built and validated for 8-channel multispectral imaging within 420~720 nm wavelength range on both macro and micro objects, showing a potential for efficient multispectral imager in macroscopic and biomedical applications.

  8. Zn Electrodeposition on Single-Crystal GaN(0001 Surface: Nucleation and Growth Mechanism

    Directory of Open Access Journals (Sweden)

    Fei Peng

    2016-01-01

    Full Text Available The electrochemical deposition of zinc on single-crystal n-type GaN(0001 from a sulphate solution has been investigated on the basis of electrochemical techniques including cyclic voltammetry, chronoamperometry, and Tafel plot. The morphology and crystal structure of zinc deposits have been characterized by means of scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray analysis. The result has revealed that the deposition of Zn on GaN electrode commenced at a potential of −1.12 V versus Ag/AgCl. According to the Tafel plot, an exchange current density of ~0.132 mA cm−2 was calculated. In addition, the current transient measurements have shown that Zn deposition process followed the instantaneous nucleation in 10 mM ZnSO4 + 0.5 M Na2SO4 + 0.5 M H3BO3 (pH = 4.

  9. Electrochemical deposition of copper on single-crystal gallium nitride(0001) electrode: nucleation and growth mechanism

    International Nuclear Information System (INIS)

    Zhao, Yu; Deng, Feng-Xiang; Hu, Li-Feng; Liu, Yong-Qiang; Pan, Ge-Bo

    2014-01-01

    Highlights: • The nucleation and growth of Cu electrodeposition on n-GaN was explored. • The Cu deposition commenced at a large negative potential of −840 mV vs. Pt/Pt 2+ . • The deposition process was quasi-reversible and mass transfer limited. • The deposition occurred on the conduction band of n-GaN. - Abstract: The electrodeposition of Cu on n-type single-crystal GaN(0001) electrode from sulfate solution was investigated by electrochemical techniques and scanning electron microscopy. It was found that Cu deposition on GaN(0001) commenced at a large negative potential of −840 mV vs. Pt/Pt 2+ and was quasi-reversible and mass transfer limited. On the basis of Tafel plot, a low exchange current density of ∼ 2.3 × 10 −6 mA cm −2 was calculated. This was mainly due to the limited free electrons in the conduction band of GaN. In addition, the current transient measurements revealed that the deposition process followed the progressive nucleation in 0.5 M H 2 SO 4 + 5 mM CuSO 4 . The instantaneous nucleation was observed only at the large applied potential of −1.1 V

  10. Transport of single-walled carbon nanotubes in porous media: filtration mechanisms and reversibility.

    Science.gov (United States)

    Jaisi, Deb P; Saleh, Navid B; Blake, Ruth E; Elimelech, Menachem

    2008-11-15

    Deposition of nanomaterials onto surfaces is a key process governing their transport, fate, and reactivity in aquatic systems. We evaluated the transport and deposition behavior of carboxyl functionalized single-walled carbon nanotubes (SWNTs) in a well-defined porous medium composed of clean quartz sand over a range of solution chemistries. Our results showthat increasing solution ionic strength or addition of calcium ions result in increased SWNT deposition (filtration). This observation is consistent with conventional colloid deposition theories, thereby suggesting that physicochemical filtration plays an important role in SWNT transport. However, the relatively insignificant change of SWNT filtration at low ionic strengths (water (C/Co = 0.90) indicate that physical straining also plays a role in the capture of SWNTs within the packed sand column. It is proposed that SWNT shape and structure, particularly the very large aspect ratio and its highly bundled (aggregated) state in aqueous solutions, contribute considerably to straining in flow through porous media. We conclude that both physicochemical filtration and straining play a role at low (introduction of low ionic strength solution following deposition experiments with monovalent salt (KCl). In contrast, SWNTs deposited in the presence of calcium ions were not released upon introduction of low ionic strength solution to the packed column, even when humic acid was present in solution during SWNT deposition.

  11. Overexpression of cypin alters dendrite morphology, single neuron activity, and network properties via distinct mechanisms

    Science.gov (United States)

    Rodríguez, Ana R.; O'Neill, Kate M.; Swiatkowski, Przemyslaw; Patel, Mihir V.; Firestein, Bonnie L.

    2018-02-01

    Objective. This study investigates the effect that overexpression of cytosolic PSD-95 interactor (cypin), a regulator of synaptic PSD-95 protein localization and a core regulator of dendrite branching, exerts on the electrical activity of rat hippocampal neurons and networks. Approach. We cultured rat hippocampal neurons and used lipid-mediated transfection and lentiviral gene transfer to achieve high levels of cypin or cypin mutant (cypinΔPDZ PSD-95 non-binding) expression cellularly and network-wide, respectively. Main results. Our analysis revealed that although overexpression of cypin and cypinΔPDZ increase dendrite numbers and decrease spine density, cypin and cypinΔPDZ distinctly regulate neuronal activity. At the single cell level, cypin promotes decreases in bursting activity while cypinΔPDZ reduces sEPSC frequency and further decreases bursting compared to cypin. At the network level, by using the Fano factor as a measure of spike count variability, cypin overexpression results in an increase in variability of spike count, and this effect is abolished when cypin cannot bind PSD-95. This variability is also dependent on baseline activity levels and on mean spike rate over time. Finally, our spike sorting data show that overexpression of cypin results in a more complex distribution of spike waveforms and that binding to PSD-95 is essential for this complexity. Significance. Our data suggest that dendrite morphology does not play a major role in cypin action on electrical activity.

  12. Electronic transport mechanism and photocurrent generations of single-crystalline InN nanowires

    Science.gov (United States)

    Lee, Sunghun; Lee, Wonjoo; Seo, Kwanyong; Kim, Jinhee; Han, Sung-Hwan; Kim, Bongsoo

    2008-10-01

    Nanodevices using individual indium nitride nanowires are fabricated by e-beam lithography. The nanowires have diameters of 40-80 nm, lengths up to several tens of micrometres and single-crystalline nature. We observed ohmic I-V behaviour of InN nanowires above nearly 100 K, which is consistent with the pinning Fermi level of the metal electrode near the conduction band edge of InN nanowire. At low temperatures, the device shows typical semiconductor behaviour along with a quantum tunnelling effect through the Schottky barrier rather than thermally activated transport. The activation energy calculated above and below 80 K is 28.2 and 5.08 meV, respectively. We have also fabricated a photocurrent generation device using InN nanowires. The photocurrent of an acceptor-sensitizer dyad with di-(3-aminopropyl)-viologen (DAPV) and a Ru complex on an InN nanowires/ITO plate was 8.3 nA cm-2, which increased by 62.7% compared to that without InN nanowire layers.

  13. Fabrication of a mechanically aligned single-wafer MEMS turbine with turbocharger

    Science.gov (United States)

    Pelekies, S. O.; Schuhmann, T.; Gardner, W. G.; Camacho, A.; Protz, J. M.

    2010-10-01

    We describe the fabrication of a turbocharged, microelectromechanical system (MEMS) turbine. The turbine will be part of a standalone power unit and includes extra layers to connect the turbine to a generator. The project goal is to demonstrate the successful combination of several features, namely: silicon fusion bonding (SFB), a micro turbocharger [2], two rotors, mechanical alignment between two wafers [1], and the use of only one 5" silicon wafer. The dimension of the actual turbine casing will be 14mm. The turbine rotor will have a diameter of 8mm. Given these dimensions, MEMS processes are an adequate way to fabricate the device, but it will be necessary to stack up seven different layers to build the turbine, as it is not possible to construct it out of one thick wafer. SFB will be used for bonding because it permits the great precision necessary for high quality alignment. Yet a more precise alignment will be necessary between the layers that contain the turbine rotor, to decrease imbalance and guarantee operation at a very high rpm. To achieve these tight tolerances, a mechanical alignment feature announced by Liudi Jiang [1] is used. The alignment accuracy is expected to be around 200nm. Despite the fact that the turbine consists of multiple layers, it will be fabricated on only one silicon-on-insulator (SOI) wafer. As a result, all layers are exposed to the same process flow. The fabrication process includes MEMS technology as photolithography, nine deep reactive ion etching (DRIE) steps, and six SFB operations. A total of 14 masks are necessary for the fabrication.

  14. Elastic hydrogel as a sensor for detection of mechanical stress generated by single cells grown in three-dimensional environment.

    Science.gov (United States)

    Huang, Jianyong; Wang, Liangli; Xiong, Chunyang; Yuan, Fan

    2016-08-01

    Cell volume growth occurs in all living tissues. The growth exerts mechanical stresses on surrounding tissues that may alter tissue microenvironment, and have significant implications in health and diseases. However, the level of growth stress generated by single cells in three-dimensional (3D) environment remains to be determined. To this end, we developed a growth force microscopy technique to determine 3D distribution of the stress. The technique was based on encapsulation of cells in elastic hydrogels, and involved 3D particle tracking and mechanical analysis of gel deformation. Data from the study demonstrated that the growth stress was dynamic, and the stress distribution at the gel-cell interface was correlated inversely to the mean surface curvature or the distance to the geometric center of the cell. The stress averaged over the cell surface increased with increasing gel stiffness, suggesting that cells could alter growth stress in response to stiffness change in microenvironment. These findings suggested that the elastic hydrogel-based microscopy technique had a potential to provide new insights into mechanisms of mechanical interactions between cell and its microenvironment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Dynamic quantitative visualization of single cell alignment and migration and matrix remodeling in 3-D collagen hydrogels under mechanical force.

    Science.gov (United States)

    Pang, Yonggang; Wang, Xiaoli; Lee, Dongkeun; Greisler, Howard P

    2011-05-01

    We developed a live imaging system enabling dynamic visualization of single cell alignment induced by external mechanical force in a 3-D collagen matrix. The alignment dynamics and migration of smooth muscle cells (SMCs) were studied by time lapse differential interference contrast and/or phase contrast microscopy. Fluorescent and reflection confocal microcopy were used to study the SMC morphology and the microscale collagen matrix remodeling induced by SMCs. A custom developed program was used to quantify the cell migration and matrix remodeling. Our system enables cell concentration-independent alignment eliminating cell-to-cell interference and enables dynamic cell tracking, high magnification observation and rapid cell alignment accomplished in a few hours compared to days in traditional models. We observed that cells sense and response to the mechanical signal before cell spreading. Under mechanical stretch the migration directionality index of SMCs is 46.3% more than those cells without external stretch; the dynamic direction of cell protrusion is aligned to that of the mechanical force; SMCs showed directional matrix remodeling and the alignment index calculated from the matrix in front of cell protrusions is about 3 fold of that adjacent to cell bodies. Our results indicate that the mechanism of cell alignment is directional cell protrusion. Mechano-sensing, directionality in cell protrusion dynamics, cell migration and matrix remodeling are highly integrated. Our system provides a platform for studying the role of mechanical force on the cell matrix interactions and thus finds strategies to optimize selected properties of engineered tissues. Published by Elsevier Ltd.

  16. Parallels and Differences in the Attitudes towards Single-Firm Conduct: What are the Reasons? The History, Interpretation and Underlying Principles of Sec. 2 Sherman Act and Art. 82 EC

    OpenAIRE

    SCHWEITZER, Heike

    2007-01-01

    In the US and in the EU, the antitrust rules on single-firm conduct are currently under review. Antitrust authorities on both sides of the Atlantic are reconsidering the tests to be applied in order to distinguish between lawful competition on the merits and exclusionary conduct. In the transatlantic comparison that accompanies the review, it has been observed that in the US, the tests for identifying anti-competitive single-firm conduct under Sec. 2 Sherman Act are frequently ...

  17. Effect of Casting Parameters on the Microstructural and Mechanical Behavior of Magnesium AZ31-B Alloy Strips Cast on a Single Belt Casting Simulator

    Directory of Open Access Journals (Sweden)

    Ahmad Changizi

    2014-01-01

    Full Text Available Strips of magnesium alloy AZ31-B were cast on a simulator of a horizontal single belt caster incorporating a moving mold system. Mixtures of CO2 and sulfur hexafluoride (SF6 gases were used as protective atmosphere during melting and casting. The castability of the AZ31-B strips was investigated for a smooth, low carbon steel substrate, and six copper substrates with various textures and roughnesses. Graphite powder was used to coat the substrates. The correlation between strip thickness and heat flux was investigated. It was found that the heat flux from the forming strip to the copper substrate was higher than that to the steel substrate, while coated substrates registered lower heat fluxes than uncoated substrates. The highest heat flux from the strip was recorded for casting on macrotextured copper substrates with 0.15 mm grooves. As the thickness of the strip decreased, the net heat flux decreased. As the heat flux increased, the grain sizes of the strips were reduced, and the SDAS decreased. The mechanical properties were improved when the heat flux increased. The black layers which formed on the strips’ surfaces were analyzed and identified as nanoscale MgO particles. Nano-Scale particles act as light traps and appeared black.

  18. Optimized design and structural mechanics of a single-piece composite helicopter driveshaft

    Science.gov (United States)

    Henry, Todd C.

    In rotorcraft driveline design, single-piece composite driveshafts have much potential for reducing driveline mass and complexity over multi-segmented metallic driveshafts. The singlepiece shaft concept is enabled by the relatively high fatigue strain capacity of fiber reinforced polymer composites over metals. Challenges for single-piece driveshaft design lie in addressing the self-heating behavior of the composite due to the material damping, as well as, whirling stability, torsional buckling stability, and composite strength. Increased composite temperature due to self-heating reduces the composite strength and is accounted for in this research. The laminate longitudinal stiffness ( Ex) and strength (Fx) are known to be heavily degraded by fiber undulation, however, both are not well understood in compression. The whirling stability (a function of longitudinal stiffness) and the composite strength are strongly influential in driveshaft optimization, and thus are investigated further through the testing of flat and filament wound composite specimens. The design of single-piece composite driveshafts, however, needs to consider many failure criteria, including hysteresis-induced overheating, whirl stability, torsional buckling stability, and material failure by overstress. The present investigation uses multi-objective optimization to investigate the design space which visually highlights design trades. Design variables included stacking sequence, number of laminas, and number of hanger bearings. The design goals were to minimize weight and maximize the lowest factor of safety by adaptively generating solutions to the multi-objective problem. Several design spaces were investigated by examining the effect of misalignment, ambient temperature, and constant power transmission on the optimized solution. Several materials of interest were modeled using experimentally determined elastic properties and novel temperature-dependent composite strength. Compared to the

  19. Exploring particulate retention mechanisms through visualization of E. coli transport through a single, saturated fracture

    Science.gov (United States)

    Burke, M. G.; Dickson, S. E.; Schutten, M.

    2011-12-01

    Groundwater is an extremely valuable resource; a large body of work has been conducted towards remediating, tracking and reducing its contamination. Even so, there are large gaps within the current understanding of groundwater flow and contaminant transport, particularly within fractured media. Fractured media has the ability transport contaminants over longer distances in less time relative to porous media. Furthermore, colloids display unique transport characteristics in comparison to dissolved constituents, including the fact that they typically exhibit earlier initial arrival times. Of particular concern to human health are pathogenic microorganisms, which often originate from fecal contamination. Escherichia coli is a common indicator for fecal contamination; some strains are pathogenic, causing acute illness and sometimes death, in humans. A comprehensive understanding of the transport and retention of E. coli in fractured media will improve our ability to accurately assess whether a site is at risk of becoming contaminated by pathogenic microorganisms. Therefore, the goal of this work is to expand our mechanistic understanding particulate retention, specifically E. coli, in fractures, and the influence of flow rate on these mechanisms. In order to achieve this goal, clear epoxy casts were fabricated of two dolomitic limestone fractures retrieved from a quarry in Guelph, Ontario. Each aperture field was characterized through hydraulic and tracer tests, and measured directly using the light transmission technique. E. coli RS2-GFP, which is a non-pathogenic strain of E. coli that has been tagged with a green fluorescent protein, was injected into the cast under three separate specific discharges ranging from 5 - 30 m/d. These experiments were conducted on an ultraviolet light source, and a high resolution charged-couple device (CCD) camera was employed to take photos at regular intervals in order to capture the dominant flow paths and the areas of retention

  20. Study of the mechanical properties of single- layer and multi-layer metallic coatings with protective-decorative applications

    Directory of Open Access Journals (Sweden)

    Cherneva Sabina

    2018-01-01

    Full Text Available Single thin coating of matt nickel (Nimat, a mirror bright copper (Cubright, a mirror bright nickel (Nibright and their combinations were electrochemically deposited on brass substrate with thickness 500 μm. The basic aim was electrodeposition of two-layer Cubright/Nimat and Nibright/Cubright systems, and three-layer Nibright Cubrigh/Nimat system, which are among the most widely applied protective and decorative systems in light and medium operating conditions of corrosion. The thicknesses of the obtained films varied from 1 μm to 3.25 μm. They were investigated via nanoindentation experiments, in order to characterize their basic physical and mechanical characteristics, related with their good adhesion and corrosion protective ability, as well as ensuring the integrity of the system “protective coating/substrate” to possible mechanical, dynamic and/or thermal stresses. As a result, load-displacement curves were obtained and indentation hardness and indentation modulus were calculated using the Oliver & Pharr approximation method. The dependence of the indentation modulus and the indentation hardness on the depth of the indentation, surface morphology and structure of the obtained coatings, their texture and surface roughness were investigated too. The obtained results showed that the three-layer Nibright/Cubright /Niimat/CuZn37 system has highest indentation modulus and indentation hardness, following by two-layer Nibright/Cubright system and single layer coatings.

  1. A polypeptide-DNA hybrid with selective linking capability applied to single molecule nano-mechanical measurements using optical tweezers.

    Directory of Open Access Journals (Sweden)

    Fatemeh Moayed

    Full Text Available Many applications in biosensing, biomaterial engineering and single molecule biophysics require multiple non-covalent linkages between DNA, protein molecules, and surfaces that are specific yet strong. Here, we present a novel method to join proteins and dsDNA molecule at their ends, in an efficient, rapid and specific manner, based on the recently developed linkage between the protein StrepTactin (STN and the peptide StrepTag II (ST. We introduce a two-step approach, in which we first construct a hybrid between DNA and a tandem of two STs peptides (tST. In a second step, this hybrid is linked to polystyrene bead surfaces and Maltose Binding Protein (MBP using STN. Furthermore, we show the STN-tST linkage is more stable against forces applied by optical tweezers than the commonly used biotin-Streptavidin (STV linkage. It can be used in conjunction with Neutravidin (NTV-biotin linkages to form DNA tethers that can sustain applied forces above 65 pN for tens of minutes in a quarter of the cases. The method is general and can be applied to construct other surface-DNA and protein-DNA hybrids. The reversibility, high mechanical stability and specificity provided by this linking procedure make it highly suitable for single molecule mechanical studies, as well as biosensing and lab on chip applications.

  2. Thermo-Mechanical Analysis of a Single-Pass Weld Overlay and Girth Welding in Lined Pipe

    Science.gov (United States)

    Obeid, Obeid; Alfano, Giulio; Bahai, Hamid

    2017-08-01

    The paper presents a nonlinear heat-transfer and mechanical finite-element (FE) analyses of a two-pass welding process of two segments of lined pipe made of a SUS304 stainless steel liner and a C-Mn steel pipe. The two passes consist of the single-pass overlay welding (inner lap weld) of the liner with the C-Mn steel pipe for each segment and the single-pass girth welding (outer butt weld) of the two segments. A distributed power density of the moving welding torch and a nonlinear heat-transfer coefficient accounting for both radiation and convection have been used in the analysis and implemented in user subroutines for the FE code ABAQUS. The modeling procedure has been validated against previously published experimental results for stainless steel and carbon steel welding separately. The model has been then used to determine the isotherms induced by the weld overlay and the girth welding and to clarify their influence on the transient temperature field and residual stress in the lined pipe. Furthermore, the influence of the cooling time between weld overlay and girth welding and of the welding speed have been examined thermally and mechanically as they are key factors that can affect the quality of lined pipe welding.

  3. Advanced Propfan Engine Technology (APET) definition study, single and counter-rotation gearbox/pitch change mechanism design

    Science.gov (United States)

    Anderson, R. D.

    1985-01-01

    Single-rotation propfan-powered regional transport aircraft were studied to identify key technology development issues and programs. The need for improved thrust specific fuel consumption to reduce fuel burned and aircraft direct operating cost is the dominant factor. Typical cycle trends for minimizing fuel consumption are reviewed, and two 10,000 shp class engine configurations for propfan propulsion systems for the 1990's are presented. Recommended engine configurations are both three-spool design with dual spool compressors and free power turbines. The benefits of these new propulsion system concepts were evaluated using an advanced airframe, and results are compared for single-rotation propfan and turbofan advanced technology propulsion systems. The single-rotation gearbox is compared to a similar design with current technology to establish the benefits of the advanced gearbox technology. The conceptual design of the advanced pitch change mechanism identified a high pressure hydraulic system that is superior to the other contenders and completely external to the gearboxes.

  4. A single-patterned five-band terahertz metamaterial absorber based on multiple resonance mechanisms

    Science.gov (United States)

    Ju, Zong-De; Xu, Guo-Qing; Wei, Zhi-Hua; Li, Jing; Zhao, Qian; Huang, Jie

    2018-01-01

    A single-patterned five-band terahertz metamaterial absorber based on simple metal-dielectric-metal sandwich structure is investigated and demonstrated. The numerical simulations reveal the different dependence of the absorption ability on the incident polarization angle, dielectric layer, and structural dimensions of the single pattern. The extracted electric field distribution indicates that the five-band near-perfect absorption performance (average over 98%) mainly originates from the combination of LC, dipole, quadrupole, and high-order resonance. The researches on magnetic field and power loss density distributions further reveal the absorption mechanism. Moreover, additional resonance mode can be excited to form a six-band high-performance absorber only by adjusting some geometric dimensions of the single pattern with multiple resonance modes. The simple method provides us a very good idea to implement a super multi-band absorber. The proposed absorbers here can be applied in massive related fields, such as metamaterial sensors, thermal radiation, and imaging system.

  5. Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Nagapandiselvi, P., E-mail: nagapandiselvip@ssn.edu.in [Department of Physics, SSN College of Engineering, Kalavakkam (India); Baby, C. [Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai (India); Gopalakrishnan, R. [Crystal Research Lab, Department of Physics, Anna University, Chennai (India)

    2016-09-15

    Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra established the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.

  6. Foot muscle morphology is related to center of pressure sway and control mechanisms during single-leg standing.

    Science.gov (United States)

    Zhang, Xianyi; Schütte, Kurt Heinrich; Vanwanseele, Benedicte

    2017-09-01

    Maintaining balance is vitally important in everyday life. Investigating the effects of individual foot muscle morphology on balance may provide insights into neuromuscular balance control mechanisms. This study aimed to examine the correlation between the morphology of foot muscles and balance performance during single-leg standing. Twenty-eight recreational runners were recruited in this study. An ultrasound device was used to measure the thickness and cross-sectional area of three intrinsic foot muscles (abductor hallucis, flexor digitorum brevis and quadratus plantae) and peroneus muscles. Participants were required to perform 30s of single-leg standing for three trials on a force plate, which was used to record the center of pressure (COP). The standard deviation of the amplitude and ellipse area of the COP were calculated. In addition, stabilogram diffusion analysis (SDA) was performed on COP data. Pearson correlation coefficients were computed to examine the correlation between foot muscle morphology and traditional COP parameters as well as with SDA parameters. Our results showed that larger abductor hallucis correlated to smaller COP sway, while larger peroneus muscles correlated to larger COP sway during single-leg standing. Larger abductor hallucis also benefited open-loop dynamic stability, as well as supported a more efficient transfer from open-loop to closed loop control mechanisms. These results suggest that the morphology of foot muscles plays an important role in balance performance, and that strengthening the intrinsic foot muscles may be an effective way to improve balance. Copyright © 2017. Published by Elsevier B.V.

  7. Neuromuscular Control Mechanisms During Single-Leg Jump Landing in Subacute Ankle Sprain Patients: A Case Control Study.

    Science.gov (United States)

    Allet, Lara; Zumstein, Franziska; Eichelberger, Patric; Armand, Stéphane; Punt, Ilona M

    2017-03-01

    Optimal neuromuscular control mechanisms are essential for preparing, maintaining, and restoring functional joint stability during jump landing and to prevent ankle injuries. In subacute ankle sprain patients, neither muscle activity nor kinematics during jump landing has previously been assessed. To compare neuromuscular control mechanisms and kinematics between subacute ankle sprain patients and healthy persons before and during the initial contact phase of a 25-cm single-leg jump. Case-control study. University hospital. Fifteen patients with grade I or II acute ankle sprains were followed up after 4 weeks of conservative management not involving physical therapy. Subjects performed alternately 3 single-leg forward jumps of 25 cm (toe-to-heel distance) barefoot. Their results were compared with the data of 15 healthy subjects. Electromyographic (EMG) activity of the musculus (m.) gastrocnemius lateralis, m. tibialis anterior, and m. peroneus longus as well as kinematics for ankle, knee, and hip joint were recorded for pre-initial contact (IC) phase, post-initial contact phase, and reflex-induced phase. The results showed that EMG activity of the 3 muscles did not differ between ankle sprain patients (n = 15) and healthy persons (n = 15) for any of the analyzed time intervals (all P > .05). However, during the pre-IC phase, ankle sprain patients presented less plantar flexion, as well as during the post-IC phase after jump landing, compared to healthy persons (P ankle joint can lead to neuromuscular control mechanism disturbances through which functional instability might arise. III. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  8. A novel mechanism of high-level, broad-spectrum antibiotic resistance caused by a single base pair change in Neisseria gonorrhoeae.

    Science.gov (United States)

    Ohneck, Elizabeth A; Zalucki, Yaramah M; Johnson, Paul J T; Dhulipala, Vijaya; Golparian, Daniel; Unemo, Magnus; Jerse, Ann E; Shafer, William M

    2011-01-01

    aid in the development of new antimicrobial therapies and genetic methods for antimicrobial resistance testing. This study was undertaken to characterize a novel mechanism of antibiotic resistance regulation in N. gonorrhoeae. Here we show that a single base pair mutation generates a second, stronger promoter for mtrCDE transcription that acts independently of the known efflux system regulators and results in high-level antimicrobial resistance.

  9. Structural, mechanical and light yield characterisation of heat treated LYSO:Ce single crystals for medical imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Mengucci, P., E-mail: p.mengucci@univpm.it [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); André, G. [Laboratoire Léon Brillouin, CEA-CNRS, CE-Saclay, 91191 Gif sur Yvette cedex (France); Auffray, E. [Department PH-CMX CERN, Route de Meyrin, 1211 Geneva 23 (Switzerland); Barucca, G. [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Cecchi, C. [Dipartimento di Fisica e Geologia, Università di Perugia, Via A. Pascoli, 06123 Perugia (Italy); Chipaux, R. [CEA DSM/IRFU/SEDI, CE-Saclay, 91191 Gif sur Yvette cedex (France); Cousson, A. [Laboratoire Léon Brillouin, CEA-CNRS, CE-Saclay, 91191 Gif sur Yvette cedex (France); Davì, F. [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Di Vara, N. [Department PH-CMX CERN, Route de Meyrin, 1211 Geneva 23 (Switzerland); Rinaldi, D.; Santecchia, E. [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy)

    2015-06-11

    Five single crystals of cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) grown by the Czochralski method were submitted to structural characterisation by X-ray (XRD) and neutron (ND) diffraction, scanning (SEM) and transmission (TEM) electron microscopy and energy dispersive microanalysis (EDS). The Ultimate Tensile Strength (UTS), the Young Modulus (YM) and the Light Yield (LY) of the samples were also measured in order to correlate the mechanical and the optical behaviour of the crystals with the characteristics of their microstructure. Two of the samples analysed were also heat treated at 300 °C for 10 h to evidence possible variations induced by the temperature in the optical and mechanical response of the crystals. Results showed that the mean compositional variations evidenced by the structural analyses do not affect the mechanical and optical behaviour of the samples. On the contrary, the thermal treatment could induce the formation of coherent spherical particles (size 10 to 15 nm), not uniformly distributed inside the sample, that strongly reduce the UTS and YM values, but it does not affect the optical response of the crystal. This latter result was attributed to the low value of the heating temperature (300 °C) that is not sufficiently high to induce annealing of the oxygen vacancies traps that are responsible of the deterioration of the scintillation properties of the LYSO:Ce crystals. This study was carried out in the framework of the Crystal Clear Collaboration (CCC)

  10. Single or in Combination Antimicrobial Resistance Mechanisms of Klebsiella pneumoniae Contribute to Varied Susceptibility to Different Carbapenems

    Science.gov (United States)

    Tsai, Yu-Kuo; Liou, Ci-Hong; Fung, Chang-Phone; Lin, Jung-Chung; Siu, L. Kristopher

    2013-01-01

    Resistance to carbapenems has been documented by the production of carbapenemase or the loss of porins combined with extended-spectrum β-lactamases or AmpC β-lactamases. However, no complete comparisons have been made regarding the contributions of each resistance mechanism towards carbapenem resistance. In this study, we genetically engineered mutants of Klebsiella pneumoniae with individual and combined resistance mechanisms, and then compared each resistance mechanism in response to ertapenem, imipenem, meropenem, doripenem and other antibiotics. Among the four studied carbapenems, ertapenem was the least active against the loss of porins, cephalosporinases and carbapenemases. In addition to the production of KPC-2 or NDM-1 alone, resistance to all four carbapenems could also be conferred by the loss of two major porins, OmpK35 and OmpK36, combined with CTX-M-15 or DHA-1 with its regulator AmpR. Because the loss of OmpK35/36 alone or the loss of a single porin combined with bla CTX-M-15 or bla DHA-1-ampR expression was only sufficient for ertapenem resistance, our results suggest that carbapenems other than ertapenem should still be effective against these strains and laboratory testing for non-susceptibility to other carbapenems should improve the accurate identification of these isolates. PMID:24265784

  11. High Temperature Deformation Mechanism in Hierarchical and Single Precipitate Strengthened Ferritic Alloys by In Situ Neutron Diffraction Studies

    Science.gov (United States)

    Song, Gian; Sun, Zhiqian; Li, Lin; Clausen, Bjørn; Zhang, Shu Yan; Gao, Yanfei; Liaw, Peter K.

    2017-04-01

    The ferritic Fe-Cr-Ni-Al-Ti alloys strengthened by hierarchical-Ni2TiAl/NiAl or single-Ni2TiAl precipitates have been developed and received great attentions due to their superior creep resistance, as compared to conventional ferritic steels. Although the significant improvement of the creep resistance is achieved in the hierarchical-precipitate-strengthened ferritic alloy, the in-depth understanding of its high-temperature deformation mechanisms is essential to further optimize the microstructure and mechanical properties, and advance the development of the creep resistant materials. In the present study, in-situ neutron diffraction has been used to investigate the evolution of elastic strain of constitutive phases and their interactions, such as load-transfer/load-relaxation behavior between the precipitate and matrix, during tensile deformation and stress relaxation at 973 K, which provide the key features in understanding the governing deformation mechanisms. Crystal-plasticity finite-element simulations were employed to qualitatively compare the experimental evolution of the elastic strain during tensile deformation at 973 K. It was found that the coherent elastic strain field in the matrix, created by the lattice misfit between the matrix and precipitate phases for the hierarchical-precipitate-strengthened ferritic alloy, is effective in reducing the diffusional relaxation along the interface between the precipitate and matrix phases, which leads to the strong load-transfer capability from the matrix to precipitate.

  12. Security analysis with improved design of post-confirmation mechanism for quantum sealed-bid auction with single photons

    Science.gov (United States)

    Zhang, Ke-Jia; Kwek, Leong-Chuan; Ma, Chun-Guang; Zhang, Long; Sun, Hong-Wei

    2018-02-01

    Quantum sealed-bid auction (QSA) has been widely studied in quantum cryptography. For a successful auction, post-confirmation is regarded as an important mechanism to make every bidder verify the identity of the winner after the auctioneer has announced the result. However, since the auctioneer may be dishonest and collude with malicious bidders in practice, some potential loopholes could exist. In this paper, we point out two types of collusion attacks for a particular post-confirmation technique with EPR pairs. And it is not difficult to see that there exists no unconditionally secure post-confirmation mechanism in the existing QSA model, if the dishonest participants have the ability to control multiparticle entanglement. In the view of this, we note that some secure implementation could exist if the participants are supposed to be semi-quantum, i.e., they can only control single photons. Finally, two potential methods to design post-confirmation mechanism are presented in this restricted scenario.

  13. Dually cross-linked single network poly(acrylic acid) hydrogels with superior mechanical properties and water absorbency.

    Science.gov (United States)

    Zhong, Ming; Liu, Yi-Tao; Liu, Xiao-Ying; Shi, Fu-Kuan; Zhang, Li-Qin; Zhu, Mei-Fang; Xie, Xu-Ming

    2016-06-28

    Poly(acrylic acid) (PAA) hydrogels with superior mechanical properties, based on a single network structure with dual cross-linking, are prepared by one-pot free radical polymerization. The network structure of the PAA hydrogels is composed of dual cross-linking: a dynamic and reversible ionic cross-linking among the PAA chains enabled by Fe(3+) ions, and a sparse covalent cross-linking enabled by a covalent cross-linker (Bis). Under deformation, the covalently cross-linked PAA chains remain intact to maintain their original configuration, while the Fe(3+)-enabled ionic cross-linking among the PAA chains is broken to dissipate energy and then recombined. It is found that the mechanical properties of the PAA hydrogels are significantly influenced by the contents of covalent cross-linkers, Fe(3+) ions and water, which can be adjusted within a substantial range and thus broaden the applications of the hydrogels. Meanwhile, the PAA hydrogels have excellent recoverability based on the dynamic and reversible ionic cross-linking enabled by Fe(3+) ions. Moreover, the swelling capacity of the PAA hydrogels is as high as 1800 times in deionized water due to the synergistic effects of ionic and covalent cross-linkings. The combination of balanced mechanical properties, efficient recoverability, high swelling capacity and facile preparation provides a new method to obtain high-performance hydrogels.

  14. Mechanical behavior of ultra-fine grained and nanocrystalline metals and single crystals: Experiments, modeling and simulations

    Science.gov (United States)

    Liu, Jian

    Ultra-fine grained (ufg, 100 nm viscoplastic phenomenological Khan--Liang--Farrokh (KLF) model is used to correlate the experimental results of the ufg/nc Ti. Crystal Plasticity Finite Element Method (CPFEM) with three different single crystal plasticity constitutive models is used for the purpose of incorporating strain rate and temperature effects into CPFEM. The classical and two newly developed single crystal plasticity models are used to simulate the deformation responses of single crystal aluminum. A constitutive model based on intragranular dislocation slip is shown to correlate closely to the stain rate effect and latent hardening behavior of single crystal Al. For ufg/nc face-centered cubic (FCC) material, we assume that dislocation slip is still the most important deformation mechanism while there is no interaction between dislocations within grains. We develop a constitutive model based on dislocation glide within ufg/nc grains and include all stages of dislocation activities especially their interactions with GB. An Arrhenius type rate is established based on the thermal activated depinning of dislocations from GB obstacles. The thermal strength is obtained as a function of the activation energy of the GB obstacles and the activation length. The athermal part includes the strength due to the grain size dependence and the strength due to the dislocation density. The model parameters for two ufg/nc materials are determined by comparing experimental results to the one dimensional (1D) flow stress model using a Taylor's factor. The new constitutive model is incorporated into three dimensional crystal plasticity and the crystal plasticity model is implemented into a UMAT subroutine of ABAQUS finite element program. The uniaxial deformation responses of two ufg/nc materials are simulated using the previously determined model parameters. CPFEM simulations give flow stress predictions that are very close to 1D model correlations/predictions. It is a clear

  15. Preparation and applications of mechanically exfoliated single-layer and multilayer MoS₂ and WSe₂ nanosheets.

    Science.gov (United States)

    Li, Hai; Wu, Jumiati; Yin, Zongyou; Zhang, Hua

    2014-04-15

    Although great progress has been achieved in the study of graphene, the small current ON/OFF ratio in graphene-based field-effect transistors (FETs) limits its application in the fields of conventional transistors or logic circuits for low-power electronic switching. Recently, layered transition metal dichalcogenide (TMD) materials, especially MoS2, have attracted increasing attention. In contrast to its bulk material with an indirect band gap, a single-layer (1L) MoS2 nanosheet is a semiconductor with a direct band gap of ~1.8 eV, which makes it a promising candidate for optoelectronic applications due to the enhancement of photoluminescence and high current ON/OFF ratio. Compared with TMD nanosheets prepared by chemical vapor deposition and liquid exfoliation, mechanically exfoliated ones possess pristine, clean, and high-quality structures, which are suitable for the fundamental study and potential applications based on their intrinsic thickness-dependent properties. In this Account, we summarize our recent research on the preparation, characterization, and applications of 1L and multilayer MoS2 and WSe2 nanosheets produced by mechanical exfoliation. During the preparation of nanosheets, we proposed a simple optical identification method to distinguish 1L and multilayer MoS2 and WSe2 nanosheets on a Si substrate coated with 90 and 300 nm SiO2. In addition, we used Raman spectroscopy to characterize mechanically exfoliated 1L and multilayer WSe2 nanosheets. For the first time, a new Raman peak at 308 cm(-1) was observed in the spectra of WSe2 nanosheets except for the 1L WSe2 nanosheet. Importantly, we found that the 1L WSe2 nanosheet is very sensitive to the laser power during characterization. The high power laser-induced local oxidation of WSe2 nanosheets and single crystals was monitored by Raman spectroscopy and atomic force microscopy (AFM). Hexagonal and monoclinic structured WO3 thin films were obtained from the local oxidization of single- to triple

  16. Mechanical properties of nickel-coated single-walled carbon nanotubes and their embedded gold matrix composites

    International Nuclear Information System (INIS)

    Song Haiyang; Zha Xinwei

    2010-01-01

    The effects of nickel coating on the mechanical behaviors of armchair single-walled carbon nanotubes (SWCNTs) and their embedded gold matrix composites under axial tension are investigated using molecular dynamics (MD) simulation method. The results show that the Young's moduli and tensile strength of SWCNTs obviously decrease after nickel coating. For armchair SWCNTs, the decreased ratio of the Young's moduli of SWCNTs with smaller radius is larger than that of SWCNTs with larger radius. A comparison is made between the response to Young's modulus of a composite with parallel embedded nanotube and the response of a composite with vertically embedded nanotube. The results show that the uncoated SWCNT can enhance the Young's modulus of composite under the condition of parallel embedment, but such improvement disappears under the condition of vertical embedment because the interaction between SWCNT and gold matrix is too weak for effective load transfer. However, the nickel-coated SWCNT can indeed significantly improve the composite behavior.

  17. Single Session of Functional Electrical Stimulation-Assisted Walking Produces Corticomotor Symmetry Changes Related to Changes in Poststroke Walking Mechanics.

    Science.gov (United States)

    Palmer, Jacqueline A; Hsiao, HaoYuan; Wright, Tamara; Binder-Macleod, Stuart A

    2017-05-01

    Recent research demonstrated that the symmetry of corticomotor drive with the paretic and nonparetic plantarflexor muscles was related to the biomechanical ankle moment strategy that people with chronic stroke used to achieve their greatest walking speeds. Rehabilitation strategies that promote corticomotor balance might improve poststroke walking mechanics and enhance functional ambulation. The study objectives were to test the effectiveness of a single session of gait training using functional electrical stimulation (FES) to improve plantarflexor corticomotor symmetry and plantarflexion ankle moment symmetry and to determine whether changes in corticomotor symmetry were related to changes in ankle moment symmetry within the session. This was a repeated-measures crossover study. On separate days, 20 people with chronic stroke completed a session of treadmill walking either with or without the use of FES of their ankle dorsi- and plantarflexor muscles. We calculated plantarflexor corticomotor symmetry using transcranial magnetic stimulation and plantarflexion ankle moment symmetry during walking between the paretic and the nonparetic limbs before and after each session. We compared changes and tested relationships between corticomotor symmetry and ankle moment symmetry following each session. Following the session with FES, there was an increase in plantarflexor corticomotor symmetry that was related to the observed increase in ankle moment symmetry. In contrast, following the session without FES, there were no changes in corticomotor symmetry or ankle moment symmetry. No stratification was made on the basis of lesion size, location, or clinical severity. These findings demonstrate, for the first time (to our knowledge), the ability of a single session of gait training with FES to induce positive corticomotor plasticity in people in the chronic stage of stroke recovery. They also provide insight into the neurophysiologic mechanisms underlying improvements in

  18. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures.

    Science.gov (United States)

    Shim, Hye Won; Yang, Byoung-Eun

    2015-12-01

    To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos® implants. This was a retrospective clinical study that analyzed 450 single Ankylos® implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to age, sex, implant length or diameter, bone graft, arch, and position. The 8-year CSR was 96.9%. Thirteen (2.9%) implants failed because of early osseointegration failure in 3, marginal bone loss in 6, and abutment fracture in 4. Screw loosening occurred in 10 implants (2.2%), and 10 abutment fractures occurred. All abutment fractures were located in the neck, and concurrent screw fractures were observed. The CSR and rate of screw loosening did not differ significantly according to factors. The CFR was higher in middle-aged patients (5.3% vs 0.0% in younger and older patients); for teeth in a molar position (5.8% vs 0.0% for premolar or 1.1% for anterior position); and for larger-diameter implants (4.5% for 4.5 mm and 6.7% for 5.5 mm diameter vs 0.5% for 3.5 mm diameter) (all Ptooth restoration in Koreans. However, relatively frequent abutment fractures (2.2%) were observed and some fractures resulted in implant failures. Middle-aged patients, the molar position, and a large implant diameter were associated with a high incidence of abutment fracture.

  19. Hippo pathway effectors control cardiac progenitor cell fate by acting as dynamic sensors of substrate mechanics and nanostructure

    KAUST Repository

    Mosqueira, Diogo

    2014-03-25

    Stem cell responsiveness to extracellular matrix (ECM) composition and mechanical cues has been the subject of a number of investigations so far, yet the molecular mechanisms underlying stem cell mechano-biology still need full clarification. Here we demonstrate that the paralog proteins YAP and TAZ exert a crucial role in adult cardiac progenitor cell mechano-sensing and fate decision. Cardiac progenitors respond to dynamic modifications in substrate rigidity and nanopattern by promptly changing YAP/TAZ intracellular localization. We identify a novel activity of YAP and TAZ in the regulation of tubulogenesis in 3D environments and highlight a role for YAP/TAZ in cardiac progenitor proliferation and differentiation. Furthermore, we show that YAP/TAZ expression is triggered in the heart cells located at the infarct border zone. Our results suggest a fundamental role for the YAP/TAZ axis in the response of resident progenitor cells to the modifications in microenvironment nanostructure and mechanics, thereby contributing to the maintenance of myocardial homeostasis in the adult heart. These proteins are indicated as potential targets to control cardiac progenitor cell fate by materials design. © 2014 American Chemical Society.

  20. Single-dose ethanol administration activates the hypothalamic-pituitary-adrenal axis: exploration of the mechanism of action.

    Science.gov (United States)

    Thiagarajan, A B; Mefford, I N; Eskay, R L

    1989-10-01

    Activation of the hypothalamic-pituitary-adrenal axis (HPAA) by single-dose ethanol administration, which achieved moderately high blood ethanol levels, was explored in naive rats in order to determine the mechanism of ethanol's activation of the stress axis. Adult male rats received a single dose (3.2 g/kg body weight-1 of a 12% solution of ethanol in physiological saline. The plasma concentration of immunoreactive (ir) adrenocorticotropic hormone (ACTH), beta-endorphin (BE) and corticosterone (CS) was determined by radioimmunoassay, whereas, plasma concentrations of epinephrine (E) and norepinephrine (NE) were quantified following reverse-phase liquid chromatographic separation and amperometric detection. Ethanol induced maximal plasma ACTH levels within minutes, which declined toward basal levels by 60 min, whereas, plasma concentration of CS rose rapidly and remained elevated at 60 min. Plasma ACTH and CS levels in saline-treated control animals did not vary significantly at any time point. Consistent with co-release of ACTH from corticotrophs, the plasma concentration of ir-BE increased 5-fold at 15 min and declined towards basal levels at 60 min after-ethanol challenge. Plasma E increased 10- to 20-fold as compared to saline controls or preinjection levels and returned to preinjection levels by 90 min, in a manner similar to ethanol-induced changes in proopiomelanocortin-derived peptides and CS. Removal of the adrenal medulla and thus the source of E prior to ethanol administration, did not attenuate activation of the HPAA. Passive immunoneutralization of arginine vasopressin (AVP), using a high-titer AVP antiserum and a protocol which was found to block ether-induced ACTH secretion by 40% in adult male rats, failed to even partially block ethanol-induced ACTH or CS secretion. The results of this study indicate that neither adrenal medulla-derived E nor AVP are significant regulators or coregulators of corticotroph secretions following a moderately high

  1. Growth, structural, optical, mechanical and quantum chemical analysis of unidirectional grown bis(guanidinium) 5-sulfosalicylate (BGSSA) single crystal

    Science.gov (United States)

    Sreedevi, R.; Saravana Kumar, G.; Amarsingh Bhabu, K.; Balu, T.; Murugakoothan, P.; Rajasekaran, T. R.

    2018-02-01

    Bis(guanidinium) 5-sulfosalicylate single crystal was grown by using Sankaranarayanan-Ramasamy (SR) method from the solution of methanol and water in equimolar ratio. Good quality crystal with 50 mm length and 10 mm in diameter was grown. The grown crystal was subjected to single crystal X-ray diffraction analysis to confirm the crystal structure and it was found to be orthorhombic. UV-Vis-NIR spectroscopic study revealed that the SR method grown crystal had good optical transparency with wide optical band gap of 4.4 eV. The presence of the functional groups and modes of vibrations were identified by FTIR spectroscopy recorded in the range 4000-400 cm-1. The mechanical strength of the grown crystal was confirmed using Vickers microhardness tester by applying load from 25 g to 100 g. Density functional theory (DFT) method with B3LYP/6-31-G (d,p) level basis set was employed and hence the optimized molecular geometry, first order hyperpolarizability, dipole moment, thermodynamic functions, molecular electrostatic potential and frontier molecular orbital analysis of the grown BGSSA sample was computed and analysed.

  2. Molecular dynamics study on the evolution of interfacial dislocation network and mechanical properties of Ni-based single crystal superalloys

    Science.gov (United States)

    Li, Nan-Lin; Wu, Wen-Ping; Nie, Kai

    2018-05-01

    The evolution of misfit dislocation network at γ /γ‧ phase interface and tensile mechanical properties of Ni-based single crystal superalloys at various temperatures and strain rates are studied by using molecular dynamics (MD) simulations. From the simulations, it is found that with the increase of loading, the dislocation network effectively inhibits dislocations emitted in the γ matrix cutting into the γ‧ phase and absorbs the matrix dislocations to strengthen itself which increases the stability of structure. Under the influence of the temperature, the initial mosaic structure of dislocation network gradually becomes irregular, and the initial misfit stress and the elastic modulus slowly decline as temperature increasing. On the other hand, with the increase of the strain rate, it almost has no effect on the elastic modulus and the way of evolution of dislocation network, but contributes to the increases of the yield stress and tensile strength. Moreover, tension-compression asymmetry of Ni-based single crystal superalloys is also presented based on MD simulations.

  3. Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

    Science.gov (United States)

    Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

    2018-04-01

    Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

  4. Electro-opto-mechanical radio-frequency oscillator driven by guided acoustic waves in standard single-mode fiber

    Directory of Open Access Journals (Sweden)

    Yosef London

    2017-04-01

    Full Text Available An opto-electronic radio-frequency oscillator that is based on forward scattering by the guided acoustic modes of a standard single-mode optical fiber is proposed and demonstrated. An optical pump wave is used to stimulate narrowband, resonant guided acoustic modes, which introduce phase modulation to a co-propagating optical probe wave. The phase modulation is converted to an intensity signal at the output of a Sagnac interferometer loop. The intensity waveform is detected, amplified, and driven back to modulate the optical pump. Oscillations are achieved at a frequency of 319 MHz, which matches the resonance of the acoustic mode that provides the largest phase modulation of the probe wave. Oscillations at the frequencies of competing acoustic modes are suppressed by at least 40 dB. The linewidth of the acoustic resonance is sufficiently narrow to provide oscillations at a single longitudinal mode of the hybrid cavity. Competing longitudinal modes are suppressed by at least 38 dB as well. Unlike other opto-electronic oscillators, no radio-frequency filtering is required within the hybrid cavity. The frequency of oscillations is entirely determined by the fiber opto-mechanics.

  5. Emission allowance trading under the Clean Air Act Amendments: An incentive mechanism for the adoption of Clean Coal Technologies

    International Nuclear Information System (INIS)

    South, D.W.; McDermott, K.A.

    1993-01-01

    Title IV of the Clean Air Act Amendments of 1990 (P.L. 101-549) uses tradeable SO 2 allowances as a means of reducing acidic emissions from the electricity generating industry. The use of emission allowances generates two important results; first, utilities are given the flexibility to choose their optimal (least cost) compliance strategies and second, the use of emission allowances creates greater incentives for the development and commercialization of innovative emissions control technology. Clean Coal Technologies (CCTs) are able to generate electricity more efficiently, use a wide variety of coal grades and types, and dramatically reduce emissions of SO 2 , NO x , CO 2 , and PM per kWh. However, development and adoption of the technology is limited by a variety of regulatory and technological risks. The use of SO 2 emission allowances may be able to provide incentives for utility (and nonutility) adoption of this innovative technology. Emission allowances permit the utility to minimize costs on a systemwide basis and provides rewards for addition emission reductions. As CCTs are a more efficient and low emitting source of electricity, the development and implementation of this technology is desirable. This paper will explore the relationship between the incentives created by the SO 2 allowance market and CCT development. Regulatory hindrances and boons for the allowance market shall also be identified to analyze how market development, state mandates, and incentive regulation will effect the ability of allowances to prompt CCT adoption

  6. Acute effects of single and multiple level thoracic manipulations on chronic mechanical neck pain: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Puntumetakul R

    2015-01-01

    Full Text Available Rungthip Puntumetakul,1,2 Thavatchai Suvarnnato,1,3 Phurichaya Werasirirat,1 Sureeporn Uthaikhup,2 Junichiro Yamauchi,4,5 Rose Boucaut6 1School of Physical Therapy, Faculty of Associated Medical Sciences, 2Research Center in Back, Neck, Other Joint Pain and Human Performance, 3Physical Therapy Unit, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; 4Graduate School of Human Health Sciences, Tokyo Metropolitan University, 5Future Institute for Sport Sciences, Tokyo, Japan; 6School of Health Sciences (Physiotherapy, University of South Australia, Adelaide, SA, Australia Background: Thoracic spine manipulation has become a popular alternative to local cervical manipulative therapy for mechanical neck pain. This study investigated the acute effects of single-level and multiple-level thoracic manipulations on chronic mechanical neck pain (CMNP.Methods: Forty-eight patients with CMNP were randomly allocated to single-level thoracic manipulation (STM at T6–T7 or multiple-level thoracic manipulation (MTM, or to a control group (prone lying. Cervical range of motion (CROM, visual analog scale (VAS, and the Thai version of the Neck Disability Index (NDI-TH scores were measured at baseline, and at 24-hour and at 1-week follow-up.Results: At 24-hour and 1-week follow-up, neck disability and pain levels were significantly (P<0.05 improved in the STM and MTM groups compared with the control group. CROM in flexion and left lateral flexion were increased significantly (P<0.05 in the STM group when compared with the control group at 1-week follow-up. The CROM in right rotation was increased significantly after MTM compared to the control group (P<0.05 at 24-hour follow-up. There were no statistically significant differences in neck disability, pain level at rest, and CROM between the STM and MTM groups.Conclusion: These results suggest that both single-level and multiple-level thoracic manipulation improve neck disability

  7. CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter; Austin, Phillip A.; Bacmeister, J.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; Del Genio, Anthony D.; De Roode, Stephan R.; Endo , Satoshi; Franklin, Charmaine N.; Golaz, Jean-Christophe; Hannay, Cecile; Heus, Thijs; Isotta, Francesco A.; Jean-Louis, Dufresne; Kang, In-Sik; Kawai, Hideaki; Koehler, M.; Larson, Vincent E.; Liu, Yangang; Lock, Adrian; Lohmann, U.; Khairoutdinov, Marat; Molod, Andrea M.; Neggers, Roel; Rasch, Philip J.; Sandu, Irina; Senkbeil, Ryan; Siebesma, A. P.; Siegenthaler-Le Drian, Colombe; Stevens, Bjorn; Suarez, Max; Xu, Kuan-Man; Von Salzen, Knut; Webb, Mark; Wolf, Audrey; Zhao, M.

    2013-12-26

    Large Eddy Models (LES) and Single Column Models (SCM) are used in a surrogate climate change 101 to investigate the physical mechanism of low cloud feedbacks in climate models. Enhanced surface-102 driven boundary layer turbulence and shallow convection in a warmer climate are found to be 103 dominant mechanisms in SCMs.

  8. A Modified Model Reference Adaptive Control for a Single Motor of Latch Type Control Element Drive Mechanism

    International Nuclear Information System (INIS)

    Park, Bae Jeong

    2016-01-01

    A modified Model Reference Adaptive Control (MRAC) for a single motor of latch type Control Element Drive Mechanism (CEDM) is described herein. The CEDM has complicated dynamic characteristics including electrical, mechanical, and magnetic effects. The previous control system has utilized a Proportional-Integral (PI) controller, and the control performance is limited according to nonlinear dynamic characteristics and environmental conditions. The modified MRAC using system identification (ID) technique improves the control performance in the operating condition such as model parameter variation and environmental condition change. The modified MRAC using the identified reference model with feed-forward gain and 180Hz noise reduction filter presents better performance under normal and/or abnormal condition. The simplified reference model can make H/W implementation more practical on the viewpoint of less computation and good performance. Actually, the CEDM controller shall be capable of controlling 101 control element assemblies (CEAs) individually in the nuclear power plant. Because the load conditions and the environmental condition around the 101 CEAs are all different minutely, the proposed modified MRAC can be a good practice. The modified MRAC controller will be applied in the real nuclear power plant later and this will overcome some weak point of PI controller

  9. Enhancement of the thermal and mechanical properties of polyurethane/polyvinyl chloride blend by loading single walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    A.M. Hezma

    2017-06-01

    Full Text Available Structural, thermal, and mechanical properties of pure blend and nanocomposites based on polyurethane (PU and polyvinyl chloride (PVC doped with low different content of single walled-carbon nanotubes (SWCNTs were studied. The nanocomposites at different concentration were prepared via casting technique. The interaction between PU/PVC and CNTs were examined via FT-IR studies. The changes in the structures of the nanocomposites were examined using X- Ray Diffraction (XRD, and the results indicated that the amorphous domains of nanocomposites increased with increasing SWCNTs content. Transmission electron microscope (TEM observation indicated that SWCNTs surface was wrapped with the polymer with the thermal properties of nanocomposites improved. The mechanical behavior of the nanocomposites was evaluated as a function of SWCNTs content. The main enhancement in tensile properties was observed, e.g., the tensile strength and elastic modulus increased compared with the pure blend, which may be attributed to the interaction and adhesion between CNTs and the polymer matrices due to the hydrogen bonding between carbonyl groups (C=O of polymer blend chains and carboxylic acid (COOH groups of CNTs.

  10. Development of an in vivo visual robot system with a magnetic anchoring mechanism and a lens cleaning mechanism for laparoendoscopic single-site surgery (LESS).

    Science.gov (United States)

    Feng, Haibo; Dong, Dinghui; Ma, Tengfei; Zhuang, Jinlei; Fu, Yili; Lv, Yi; Li, Liyi

    2017-12-01

    Surgical robot systems which can significantly improve surgical procedures have been widely used in laparoendoscopic single-site surgery (LESS). For a relative complex surgical procedure, the development of an in vivo visual robot system for LESS can effectively improve the visualization for surgical robot systems. In this work, an in vivo visual robot system with a new mechanism for LESS was investigated. A finite element method (FEM) analysis was carried out to ensure the safety of the in vivo visual robot during the movement, which was the most important concern for surgical purposes. A master-slave control strategy was adopted, in which the control model was established by off-line experiments. The in vivo visual robot system was verified by using a phantom box. The experiment results show that the robot system can successfully realize the expected functionalities and meet the demands of LESS. The experiment results indicate that the in vivo visual robot with high manipulability has great potential in clinical application. Copyright © 2017 John Wiley & Sons, Ltd.

  11. Single-point ACT2 gene mutation in the Arabidopsis root hair mutant der1-3 affects overall actin organization, root growth and plant development.

    Science.gov (United States)

    Vaškebová, L; Šamaj, J; Ovecka, M

    2017-12-27

    The actin cytoskeleton forms a dynamic network in plant cells. A single-point mutation in the DER1 (deformed root hairs1) locus located in the sequence of ACTIN2, a gene for major actin in vegetative tissues of Arabidopsis thaliana, leads to impaired root hair development (Ringli C, Baumberger N, Diet A, Frey B, Keller B. 2002. ACTIN2 is essential for bulge site selection and tip growth during root hair development of Arabidopsis. Plant Physiology129: 1464-1472). Only root hair phenotypes have been described so far in der1 mutants, but here we demonstrate obvious aberrations in the organization of the actin cytoskeleton and overall plant development. Organization of the actin cytoskeleton in epidermal cells of cotyledons, hypocotyls and roots was studied qualitatively and quantitatively by live-cell imaging of transgenic lines carrying the GFP-FABD2 fusion protein and in fixed cells after phalloidin labelling. Patterns of root growth were characterized by FM4-64 vital staining, light-sheet microscopy imaging and microtubule immunolabelling. Plant phenotyping included analyses of germination, root growth and plant biomass. Speed of germination, plant fresh weight and total leaf area were significantly reduced in the der1-3 mutant in comparison with the C24 wild-type. Actin filaments in root, hypocotyl and cotyledon epidermal cells of the der1-3 mutant were shorter, thinner and arranged in more random orientations, while actin bundles were shorter and had altered orientations. The wavy pattern of root growth in der1-3 mutant was connected with higher frequencies of shifted cell division planes (CDPs) in root cells, which was consistent with the shifted positioning of microtubule-based preprophase bands and phragmoplasts. The organization of cortical microtubules in the root cells of the der1-3 mutant, however, was not altered. Root growth rate of the der1-3 mutant is not reduced, but changes in the actin cytoskeleton organization can induce a wavy root growth pattern

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

    Science.gov (United States)

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

    2014-01-01

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

  13. Relating mechanical properties and chemical bonding in an inorganic-organic framework material: a single-crystal nanoindentation study.

    Science.gov (United States)

    Tan, Jin Chong; Furman, Joshua D; Cheetham, Anthony K

    2009-10-14

    We report the application of nanoindentation and atomic force microscopy to establish the fundamental relationships between mechanical properties and chemical bonding in a dense inorganic-organic framework material: Ce(C(2)O(4))(HCO(2)), 1. Compound 1 is a mixed-ligand 3-D hybrid which crystallizes in an orthorhombic space group, in which its three basic building blocks, i.e. the inorganic metal-oxygen-metal (M-O-M) chains and the two organic bridging ligands, (oxalate and formate) are all oriented perpendicular to one another. This unique architecture enabled us to decouple the elastic and plastic mechanical responses along the three primary axes of a single crystal to understand the contribution associated with stiff vs compliant basic building blocks. The (001)-oriented facet that features rigid oxalate ligands down the c-axis exhibits the highest stiffness and hardness (E approximately 78 GPa and H approximately 4.6 GPa). In contrast, the (010)-oriented facet was found to be the most compliant and soft (E approximately 43 GPa and H approximately 3.9 GPa), since the formate ligand, which is the more compliant building block within this framework, constitutes the primary linkages down the b-axis. Notably, intermediate stiffness and hardness (E approximately 52 GPa and H approximately 4.1 GPa) were measured on the (100)-oriented planes. This can be attributed to the Ce-O-Ce chains that zigzag down the a-axis (Ce...Ce metal centers form an angle of approximately 132 degrees) and also the fact that the 9-coordinated CeO(9) polyhedra are expected to be geometrically more compliant. Our results present the first conclusive evidence that the crystal orientation dominated by inorganic chains is not necessarily more robust from the mechanical properties standpoint. Rigid organic bridging ligands (such as oxalate), on the other hand, can be used to produce greater stiffness and hardness properties in a chosen crystallographic orientation. This study demonstrates that

  14. Negative Ion MALDI Mass Spectrometry of Polyoxometalates (POMs): Mechanism of Singly Charged Anion Formation and Chemical Properties Evaluation

    Science.gov (United States)

    Boulicault, Jean E.; Alves, Sandra; Cole, Richard B.

    2016-08-01

    MALDI-MS has been developed for the negative ion mode analysis of polyoxometalates (POMs). Matrix optimization was performed using a variety of matrix compounds. A first group of matrixes offers MALDI mass spectra containing abundant intact singly charged anionic adduct ions, as well as abundant in-source fragmentations at elevated laser powers. A relative ranking of the ability to induce POM fragmentation is found to be: DAN > CHCA > CNA > DIT> HABA > DCTB > IAA. Matrixes of a second group provide poorer quality MALDI mass spectra without observable fragments. Sample preparation, including the testing of salt additives, was performed to optimize signals for a model POM, POMc12, the core structure of which bears four negative charges. The matrix 9-cyanoanthracene (CNA) provided the best signals corresponding to singly charged intact POMc12 anions. Decompositions of these intact anionic species were examined in detail, and it was concluded that hydrogen radical-induced mechanisms were not prevalent, but rather that the observed prompt fragments originate from transferred energy derived from initial electronic excitation of the CNA matrix. Moreover, in obtained MALDI mass spectra, clear evidence of electron transfer to analyte POM species was found: a manifestation of the POMs ability to readily capture electrons. The affinity of polyanionic POMc12 toward a variety of cations was evaluated and the following affinity ranking was established: Fe3+ > Al3+ > Li+ > Ga3+ > Co2+ > Cr3+ > Cu2+ > [Mn2+, Mg2+] > [Na+, K+]. Thus, from the available cationic species, specific adducts are preferentially formed, and evidence is given that these higher affinity POM complexes are formed in the gas phase during the early stages of plume expansion.

  15. Prospective, multicenter, single-arm study of mechanical thrombectomy using Solitaire Flow Restoration in acute ischemic stroke.

    Science.gov (United States)

    Pereira, Vitor M; Gralla, Jan; Davalos, Antoni; Bonafé, Alain; Castaño, Carlos; Chapot, René; Liebeskind, David S; Nogueira, Raul G; Arnold, Marcel; Sztajzel, Roman; Liebig, Thomas; Goyal, Mayank; Besselmann, Michael; Moreno, Antonio; Moreno, Alfredo; Schroth, Gerhard

    2013-10-01

    Mechanical thrombectomy using stent retriever devices have been advocated to increase revascularization in intracranial vessel occlusion. We present the results of a large prospective study on the use of the Solitaire Flow Restoration in patients with acute ischemic stroke. Solitaire Flow Restoration Thrombectomy for Acute Revascularization was an international, multicenter, prospective, single-arm study of Solitaire Flow Restoration thrombectomy in patients with large vessel anterior circulation strokes treated within 8 hours of symptom onset. Strict criteria for site selection were applied. The primary end point was the revascularization rate (thrombolysis in cerebral infarction ≥2b) of the occluded vessel as determined by an independent core laboratory. The secondary end point was the rate of good functional outcome (defined as 90-day modified Rankin scale, 0-2). A total of 202 patients were enrolled across 14 comprehensive stroke centers in Europe, Canada, and Australia. The median age was 72 years, 60% were female patients. The median National Institute of Health Stroke Scale was 17. Most proximal intracranial occlusion was the internal carotid artery in 18%, and the middle cerebral artery in 82%. Successful revascularization was achieved in 79.2% of patients. Device and procedure-related severe adverse events were found in 7.4%. Favorable neurological outcome was found in 57.9%. The mortality rate was 6.9%. Any intracranial hemorrhagic transformation was found in 18.8% of patients, 1.5% were symptomatic. In this single-arm study, treatment with the Solitaire Flow Restoration device in intracranial anterior circulation occlusions results in high rates of revascularization, low risk of clinically relevant procedural complications, and good clinical outcomes in combination with low mortality at 90 days. http://www.clinicaltrials.gov. Unique identifier: NCT01327989.

  16. Comparative study between transcriptionally- and translationally-acting adenine riboswitches reveals key differences in riboswitch regulatory mechanisms.

    Directory of Open Access Journals (Sweden)

    Jean-François Lemay

    2011-01-01

    Full Text Available Many bacterial mRNAs are regulated at the transcriptional or translational level by ligand-binding elements called riboswitches. Although they both bind adenine, the adenine riboswitches of Bacillus subtilis and Vibrio vulnificus differ by controlling transcription and translation, respectively. Here, we demonstrate that, beyond the obvious difference in transcriptional and translational modulation, both adenine riboswitches exhibit different ligand binding properties and appear to operate under different regulation regimes (kinetic versus thermodynamic. While the B. subtilis pbuE riboswitch fully depends on co-transcriptional binding of adenine to function, the V. vulnificus add riboswitch can bind to adenine after transcription is completed and still perform translation regulation. Further investigation demonstrates that the rate of transcription is critical for the B. subtilis pbuE riboswitch to perform efficiently, which is in agreement with a co-transcriptional regulation. Our results suggest that the nature of gene regulation control, that is transcription or translation, may have a high importance in riboswitch regulatory mechanisms.

  17. Mechanical impedance of the sitting human body in single-axis compared to multi-axis whole-body vibration exposure.

    Science.gov (United States)

    Holmlund, P; Lundström, R

    2001-01-01

    The study was aimed to investigate the mechanical impedance of the sitting human body and to compare data obtained in laboratory single-axis investigations with multi-axis data from in vehicle measurements. The experiments were performed in a laboratory for single-axis measurements. The multi-axis exposure was generated with an eight-seat minibus where the rear seats had been replaced with a rigid one. The subjects in the multi-axis experiment all participated in the single-axis experiments. There are quite a few investigations in the literature describing the human response to single-axis exposure. The response from the human body can be expected to be affected by multi-axis input in a different way than from a single-axis exposure. The present knowledge of the effect of multiple axis exposure is very limited. The measurements were performed using a specially designed force and accelerometer plate. This plate was placed between the subject and the hard seat. Outcome shows a clear difference between mechanical impedance for multi-axis exposure compared to single-axis. This is especially clear in the x-direction where the difference is very large. The conclusion is that it seems unlikely that single-axis mechanical impedance data can be directly transferred to a multi-axis environment. This is due to the force cross-talk between different directions.

  18. Physiological effects of a single chest physiotherapy session in mechanically ventilated and extubated preterm neonates.

    Science.gov (United States)

    Mehta, Y; Shetye, J; Nanavati, R; Mehta, A

    2016-01-01

    To assess the changes on various physiological cardio-respiratory parameters with a single chest physiotherapy session in mechanically ventilated and extubated preterm neonates with respiratory distress syndrome. This is a prospective observational study in a neonatal intensive care unit setting. Sixty preterm neonates with respiratory distress syndrome, thirty mechanically ventilated and thirty extubated preterm neonates requiring chest physiotherapy were enrolled in the study. Parameters like heart rate (HR), respiratory rate (RR), Silverman Anderson score (SA score in extubated), oxygen saturation (SpO2) and auscultation findings were noted just before, immediately after chest physiotherapy but before suctioning, immediately after suctioning and after 5 minutes of the session. The mean age of neonates was 9.55±5.86 days and mean birth weight was 1550±511.5 g. As there was no significant difference in the change in parameters on intergroup comparison, further analysis was done considering two groups together (n = 60) except for SA score. As SA score was measured only in extubated neonates. HR did not change significantly during chest physiotherapy compared to the baseline but significantly decreased after 15 minutes (p = 0.01). RR and SA score significantly increased after suctioning (p = 0.014) but reduced after 15 minutes (p = physiotherapy (p = physiotherapy may help facilitate the overall well-being of a fragile preterm neonate. Lung auscultation finding suggests that after suctioning, there was a significant reduction in crepitation (p = 0.0000) but significant increase in crepitation after 15 minutes (p = physiotherapy. Chest physiotherapy is safe in preterm neonates. Suctioning causes significant cardio-respiratory parameter changes, but within normal physiological range. Thus, chest physiotherapy should be performed with continuous monitoring only when indicated and not as a routine procedure. More research is needed

  19. The mechanism of the nitric oxide-mediated enhancement of tert-butylhydroperoxide-induced DNA single strand breakage

    Science.gov (United States)

    Guidarelli, Andrea; Clementi, Emilio; Sciorati, Clara; Cantoni, Orazio

    1998-01-01

    Caffeine (Cf) enhances the DNA cleavage induced by tert-butylhydroperoxide (tB-OOH) in U937 cells via a mechanism involving Ca2+-dependent mitochondrial formation of DNA-damaging species (Guidarelli et al., 1997b). Nitric oxide (NO) is not involved in this process since U937 cells do not express the constitutive nitric oxide synthase (cNOS).Treatment with the NO donors S-nitroso-N-acetyl-penicillamine (SNAP, 10 μM), or S-nitrosoglutathione (GSNO, 300 μM), however, potentiated the DNA strand scission induced by 200 μM tB-OOH. The DNA lesions generated by tB-OOH alone, or combined with SNAP, were repaired with superimposable kinetics and were insensitive to anti-oxidants and peroxynitrite scavengers but suppressed by iron chelators.SNAP or GSNO did not cause mitochondrial Ca2+ accumulation but their enhancing effects on the tB-OOH-induced DNA strand scission were prevented by ruthenium red, an inhibitor of the calcium uniporter of mitochondria. Furthermore, the enhancing effects of both SNAP and GSNO were identical to and not additive with those promoted by the Ca2+-mobilizing agents Cf or ATP.The SNAP- or GSNO-mediated enhancement of the tB-OOH-induced DNA cleavage was abolished by the respiratory chain inhibitors rotenone and myxothiazol and was not apparent in respiration-deficient cells.It is concluded that, in cells which do not express the enzyme cNOS, exogenous NO enhances the accumulation of DNA single strand breaks induced by tB-OOH via a mechanism involving inhibition of complex III. PMID:9846647

  20. Different diffusion mechanisms of oxygen in ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re = Y, Ho) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vovk, R.V.; Boiko, Y.I.; Bogdanov, V.V.; Kamchatnaya, S.N.; Goulatis, I.L. [V. N. Karazin Kharkiv National University, 4 Svobody sq., 61077 Kharkiv (Ukraine); Chroneos, A. [Faculty of Engineering, Environment and Computing, Coventry University, Priory Street, Coventry CV1 5FB (United Kingdom); Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom)

    2017-05-15

    Highlights: • Single file diffusion mechanism of oxygen ions. • Ho modifies the diffusion mechanism in the oxygen sublattice. • Ho changes the efficient interaction of ions in CuO-planes. - Abstract: In the present study, the time dependencies of the resistivity of ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re=Y, Ho) single crystals with varying degree of deviation from oxygen stoichiometry was investigated. It was shown that the accelerated transport of oxygen ions in the initial stage of the process can be carried out along the one-dimensional non-stoichiometric vacancies’ accumulation by the single file diffusion mechanism. The final phase redistribution of oxygen ions in ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re = Y, Ho) is described by the classical mechanism of volume diffusion. The substitution of yttrium by holmium significantly affects the charge redistribution and changes the efficient interaction of ions in CuO-planes, thereby modifying the mass transfer diffusion mechanisms in the oxygen sublattice. Thus, a significant length change of the time intervals occurs, corresponding to the oxygen ions’ single file and volume diffusion mechanisms.

  1. Effect of Low Angle Grain Boundaries on Mechanical Properties of DD5 Single Crystal Ni-base Superalloy

    Directory of Open Access Journals (Sweden)

    QIN Jianchao

    2017-06-01

    Full Text Available The effects of low angle grain boundaries on the mechanical properties of second generation single crystal superalloy DD5 were investigated and the test specimens were prepared by using seeds. The results show that at 870 ℃, the yield strength and breaking strength showed no difference when the angle is below 16.1°. The elongation is higher than 15% when the angle is below 11.4°, but the elongation decreases quickly when angle is above 11.4°. At 980 ℃/250 MPa, the rupture life is higher than 130 h when the angle is below 5.1°, and decreased slowly when the angle is above 5.1°. The rupture life still remaines 85% when the angle is 14.8°. But the rupture life decreases quickly when the angle is above 14.8°.At 1093 ℃/158 MPa, the rupture life is higher than 30 h when the angle is below 5.1°, and decreases when the angle is above 5.1°.

  2. Atomic mechanism for the growth of wafer-scale single-crystal graphene: theoretical perspective and scanning tunneling microscopy investigations

    Science.gov (United States)

    Niu, Tianchao; Zhang, Jialin; Chen, Wei

    2017-12-01

    Chemical vapor deposition (CVD) is the most promising approach for producing low-cost, high-quality, and large area graphene. Revealing the graphene growth mechanism at the atomic-scale is of great importance for realizing single crystal graphene (SCG) over wafer scale. Density functional theoretical (DFT) calculations are playing an increasingly important role in revealing the structure of the most stable carbon species, understanding the evolution processes, and disclosing the active sites. Scanning tunneling microscopy (STM) is a powerful surface characterization tool to illustrate the real space distribution and atomic structures of growth intermediates during the CVD process. Combining them together can provide valuable information to improve the atomically controlled growth of SCG. Starting from a basic concept of the substrate effect on realizing SCG, this review covers the progress made in theoretical investigations on various carbon species during graphene growth on different transition metal substrates, in the STM study of the structural intermediates on transition metal surfaces, and in synthesizing graphene nanoribbons with atomic-precise width and edge structure, ending with a perspective on the future development of 2D materials beyond graphene.

  3. A First-Principle Theoretical Study of Mechanical and Electronic Properties in Graphene Single-Walled Carbon Nanotube Junctions

    Directory of Open Access Journals (Sweden)

    Ning Yang

    2017-11-01

    Full Text Available The new three-dimensional structure that the graphene connected with SWCNTs (G-CNTs, Graphene Single-Walled Carbon Nanotubes can solve graphene and CNTs′ problems. A comprehensive study of the mechanical and electrical performance of the junctions was performed by first-principles theory. There were eight types of junctions that were constituted by armchair and zigzag graphene and (3,3, (4,0, (4,4, and (6,0 CNTs. First, the junction strength was investigated. Generally, the binding energy of armchair G-CNTs was stronger than that of zigzag G-CNTs, and it was the biggest in the armchair G-CNTs (6,0. Likewise, the electrical performance of armchair G-CNTs was better than that of zigzag G-CNTs. Charge density distribution of G-CNTs (6,0 was the most homogeneous. Next, the impact factors of the electronic properties of armchair G-CNTs were investigated. We suggest that the band gap is increased with the length of CNTs, and its value should be dependent on the combined effect of both the graphene’s width and the CNTs’ length. Last, the relationship between voltage and current (U/I were studied. The U/I curve of armchair G-CNTs (6,0 possessed a good linearity and symmetry. These discoveries will contribute to the design and production of G-CNT-based devices.

  4. Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing

    Science.gov (United States)

    Villegas, Irene F.; Palardy, Genevieve

    2016-01-01

    This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints. PMID:26890931

  5. Mechanical properties of Bi,Pb(2223) single filaments and Ic(ε) behaviour in longitudinally strained tapes

    International Nuclear Information System (INIS)

    Passerini, Reynald; Dhalle, Marc; Seeber, Bernd; Fluekiger, Rene

    2002-01-01

    The Young's modulus and fracture stress of isolated Bi,Pb(2223) filaments were deduced from three-point bending tests performed at different stages of the tapes preparation. These results were introduced in the model describing the evolution of critical current of tapes submitted to a longitudinal strain in view to predict their irreversible strain limit ε irr . These calculated irreversible strain limits were compared to measured values, taken from a set of tapes made with different filling factors and composite matrices. This experiment shows that the predicted irreversible strain limits correspond to the measured ones. Presenting the I c behaviour of highly stressed tapes in a magnetic field, we discuss the evolution of the ratio I strong c0 /I c0 versus strain. This value, representative of the fraction of the critical current attributed to strongly connected grains, increases significantly during the crack formation regime at ε > ε irr . This indicates that mechanically weak links correspond to electromagnetically weak ones. This result is further confirmed by comparing the modulus of rupture obtained in single filaments extracted from tapes with different I c values

  6. Concomitant mitral valve surgery with aortic valve replacement: a 21-year experience with a single mechanical prosthesis

    Directory of Open Access Journals (Sweden)

    Sidhu Pushpinder

    2007-05-01

    Full Text Available Abstract Background Long-term survival for combined aortic and mitral valve replacement appears to be determined by the mitral valve prosthesis from our previous studies. This 21-year retrospective study assess long-term outcome and durability of aortic valve replacement (AVR with either concomitant mitral valve replacement (MVR or mitral valve repair (MVrep. We consider only a single mechanical prosthesis. Methods Three hundred and sixteen patients underwent double valve replacement (DVR (n = 273 or AVR+MVrep (n = 43, in the period 1977 to 1997. Follow up of 100% was achieved via telephone questionnaire and review of patients' medical records. Actuarial analysis of long-term survival was determined by Kaplan-Meier method. The Cox regression model was used to evaluate potential predictors of mortality. Results There were seventeen cases (5.4% of early mortality and ninety-six cases of late mortality. Fifteen-year survival was similar in both groups at 44% and 57% for DVR and AVR+MVrep respectively. There were no significant differences in valve related deaths, anticoagulation related complications, or prosthetic valve endocarditis between the groups. There were 6 cases of periprosthetic leak in the DVR group. Sex, pre-operative mitral and aortic valve pathology or previous cardiac surgery did not significantly affect outcome. Conclusion The mitral valve appears to be the determinant of survival following double valve surgery and survival is not significantly influenced by mitral valve repair.

  7. Dispersion of single-wall carbon nanotubes with supramolecular Congo red - properties of the complexes and mechanism of the interaction.

    Science.gov (United States)

    Jagusiak, Anna; Piekarska, Barbara; Pańczyk, Tomasz; Jemioła-Rzemińska, Małgorzata; Bielańska, Elżbieta; Stopa, Barbara; Zemanek, Grzegorz; Rybarska, Janina; Roterman, Irena; Konieczny, Leszek

    2017-01-01

    A method of dispersion of single-wall carbon nanotubes (SWNTs) in aqueous media using Congo red (CR) is proposed. Nanotubes covered with CR constitute the high capacity system that provides the possibility of binding and targeted delivery of different drugs, which can intercalate into the supramolecular, ribbon-like CR structure. The study revealed the presence of strong interactions between CR and the surface of SWNTs. The aim of the study was to explain the mechanism of this interaction. The interaction of CR and carbon nanotubes was studied using spectral analysis of the SWNT-CR complex, dynamic light scattering (DLS), differential scanning calorimetry (DSC) and microscopic methods: atomic force microscopy (AFM), transmission (TEM), scanning (SEM) and optical microscopy. The results indicate that the binding of supramolecular CR structures to the surface of the nanotubes is based on the "face to face stacking". CR molecules attached directly to the surface of the nanotubes can bind further, parallel-oriented molecules and form supramolecular and protruding structures. This explains the high CR binding capacity of carbon nanotubes. The presented system - containing SWNTs covered with CR - offers a wide range of biomedical applications.

  8. Privacy Act

    Science.gov (United States)

    Learn about the Privacy Act of 1974, the Electronic Government Act of 2002, the Federal Information Security Management Act, and other information about the Environmental Protection Agency maintains its records.

  9. Mechanism

    Directory of Open Access Journals (Sweden)

    Yao Yu

    2010-01-01

    Full Text Available The kinematics analysis method of a novel 3-DOF wind tunnel mechanism based on cable-driven parallel mechanism is provided. Rodrigues' parameters are applied to express the transformation matrix of the wire-driven mechanism in the paper. The analytical forward kinematics model is described as three quadratic equations using three Rodridgues' parameters based on the fundamental theory of parallel mechanism. Elimination method is used to remove two of the variables, so that an eighth-order polynomial with one variable is derived. From the equation, the eight sets of Rodridgues' parameters and corresponding Euler angles for the forward kinematical problem can be obtained. In the end, numerical example of both forward and inverse kinematics is included to demonstrate the presented forward-kinematics solution method. The numerical results show that the method for the position analysis of this mechanism is effective.

  10. Growth, mechanical, and magnetic study of SmFeO{sub 3} single crystal grown by optical floating zone technique

    Energy Technology Data Exchange (ETDEWEB)

    Babu, P. Ramesh [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhaumik, Indranil [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India); Ganesamoorthy, S. [Material Science Group, IGCAR, Kalpakkam, Tamil Nadu (India); Kalainathan, S., E-mail: kalainathan@yahoo.com [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhatt, R.; Karnal, A.K.; Gupta, P.K. [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India)

    2016-08-15

    Single crystals of Samarium orthoferrite (SmFeO{sub 3}) have been grown by the optical floating zone technique. The growth parameters to yield good quality crystals are 5 mm/h for pulling and 30–40 rpm for rotation. The mechanical behavior of the grown crystal has been investigated. Rosette pattern has been observed around the indentation and the microhardness has been found to decreases non-linearly with the applied load. For load higher than 1.96 N there is a transition from palmqvist to median crack due to plastic deformation of the crystal. The hardness parameters like fracture toughness, brittleness index, and yield strength have also been calculated for palmqvist and median cracks occurring on the crystal surface. The magnetic investigations revealed that a magnetic transition in the range of 300–180 K. Above 180 K, the magnetization decreases as Sm and Fe sublattices have opposite spins. At high temperature, two anomalies are observed, one due to near spin reorientation (T{sub SR} = 480 K) and the other is AFM to paramagnetic transitions (T{sub N} = 670 K). The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state of the SmFeO{sub 3} crystals. Bloch parameter (3.28 × 10{sup −5} K{sup −3/2}) has also been evaluated. - Highlights: • SmFeO{sub 3} single crystals have been grown by OFZ technique in air. • The microhardness has been found to decreases non-linearly with the applied load. • At 472 K, spin reorientation occurs in Fe sublattice. • The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state. • Bloch 3/2-law holds good for SmFeO{sub 3} (B-parameter as 3.28 × 10{sup −5} K{sup −3/2}).

  11. Stress-induced formation mechanism of stacking fault tetrahedra in nano-cutting of single crystal copper

    International Nuclear Information System (INIS)

    Wang, Quanlong; Bai, Qingshun; Chen, Jiaxuan; Guo, Yongbo; Xie, Wenkun

    2015-01-01

    Graphical abstract: In this paper, molecular dynamics simulation is performed to study the distribution of dislocation defects and local atomic crystal structure of single crystal copper. The stress distribution is investigated which is calculated by virial stress and analyzed by static pressure. The results are shown in (a)–(d). It is indicated that the compressive stress mainly spreads over the shear-slip zone, and the tensile stress is consisted in flank friction zone, shown in (a). The high tensile stress in subsurface is the source of stress, shown in (b). By the driven action of the stress source, the initial stair-rod dislocation nucleates. Then the dislocation climbs along four {1 1 1} planes under the stress driven action, shown in (d). Finally, the SFT is formed by the interaction of the compressive stress and the tensile stress which come from the shear-slip zone and friction zone, respectively. Besides, stair-rod dislocation, stacking faults and dislocation loop are also nucleated in the subsurface, shown in (c). Dislocation distribution, local atomic crystal structure state and stress-induced formation process of SFT by atomic. - Highlights: • A novel defect structure “stress-induced stacking fault tetrahedra” is revealed. • Atomic structural evolution and stress state distribution of the SFT are studied. • The stress-induced formation mechanism of the SFT is proposed. - Abstract: Stacking fault tetrahedra commonly existed in subsurface of deformed face center cubic metals, has great influence on machining precision and surface roughness in nano-cutting. Here we report, a stacking fault tetrahedra is formed in subsurface of workpiece during nano-cutting. The variation of cutting force and subsurface defects distribution are studied by using molecular dynamics simulation. The stress distribution is investigated which is calculated by virial stress and analyzed by static compression. The result shows that the cutting force has a rapidly

  12. A Single Atom Antenna

    International Nuclear Information System (INIS)

    Trinter, Florian; Williams, Joshua B; Weller, Miriam; Waitz, Markus; Pitzer, Martin; Voigtsberger, Jörg; Schober, Carl; Kastirke, Gregor; Müller, Christian; Goihl, Christoph; Burzynski, Phillip; Wiegandt, Florian; Wallauer, Robert; Kalinin, Anton; Schmidt, Lothar Ph H; Schöffler, Markus S; Jahnke, Till; Dörner, Reinhard; Chiang, Ying-Chih; Gokhberg, Kirill

    2015-01-01

    Here we demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single (helium) atom acting as the antenna and a second (neon) atom acting as a receiver. (paper)

  13. Effects of stereo-regularity on the single-chain mechanics of polylactic acid and its implications on the physical properties of bulk materials.

    Science.gov (United States)

    Cheng, Bo; Qian, Lu; Qian, Hu-Jun; Lu, Zhong-Yuan; Cui, Shuxun

    2017-10-05

    The material properties of polylactic acid (PLA) are largely determined by its stereo-regularity (tacticity). To find out the origin at the molecular level, the single-chain mechanics of poly-l-lactic acid (PLLA) and poly-d,l-lactide (PDLLA) were comparatively investigated by single-molecule atomic force microscopy (AFM). At a low concentration, PLLA adopted a random-coil conformation in a good solvent. At a high concentration, however, the PLLA chain can be induced into a helix, which consumed additional energy during unfolding by further stretching. Due to the random arrangement of l- and d-repeating units in the PDLLA chain, PDLLA adopts a random-coil conformation at all concentrations. The difference in single-chain mechanics of PLLA and PDLLA at high concentrations may be the cause of their different macroscopic properties. This is the first report to reveal the stereo-regularity-dependent mechanics of a polymer at the single-molecule level, which may help to bridge the gap between understanding single-molecule and materials properties.

  14. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  15. Isotherm, thermodynamic, kinetics, and adsorption mechanism studies of Ethidium bromide by single-walled carbon nanotube and carboxylate group functionalized single-walled carbon nanotube.

    Science.gov (United States)

    Moradi, Omid; Fakhri, Ali; Adami, Saeideh; Adami, Sepideh

    2013-04-01

    The studies of kinetics and thermodynamics of adsorption of Ethidium bromide in aqueous solutions on single-walled carbon nanotube (SWCNT) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces were by UV-Vis spectroscopy. The adsorption kinetics for SWCNT-COOH and SWCNTs were well described by a intra-particle diffusion model, while Langmuir, Freundlich, Harkins-Jura, and Halsey isotherms described the adsorption isotherms, and the adsorption thermodynamic parameters of equilibrium constant (K0), standard free energy (ΔG0), standard enthalpy (ΔH0), and standard entropy changes (ΔS0) were measured. The maximum surface coverage for SWCNTs is 36.10% and for SWCNT-COOH is 38.42%. The values of ΔH0 and ΔG0 suggested that the adsorption of EtBr on SWCNT-COOH and SWCNTs was endothermic and spontaneous. The adsorption of EtBr on SWCNT-COOH is more than SWCNTs surfaces. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. CO oxidation mechanism on the γ-Al{sub 2}O{sub 3} supported single Pt atom: First principle study

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Hongwei, E-mail: gaohongw369@ms.xjb.ac.cn

    2016-08-30

    Highlights: • DFT studied on CO oxidation mechanism on Pt/γ-Al{sub 2}O{sub 3} catalyst. • DFT studied on the adsorption properties of single Pt on Pt/γ-Al{sub 2}O{sub 3} catalyst. • Pt adsorptions on the Al-terminated surface are more favorable than the ones on the O-terminated surface. • The reactive O*−O−C*=O intermediate mechanism is the dominant reaction pathway for CO oxidation on Pt/γ-Al{sub 2}O{sub 3}. - Abstract: Understanding the role of metal-support interaction for the supported single-atom catalysts is very important in heterogeneous catalysis. Here, Three different CO oxidation mechanisms on Pt/γ-Al{sub 2}O{sub 3} catalyst were probed by periodic density functional theory (DFT) calculations in detail, namely the reactive O*−O−C*=O intermediate mechanism, the reactive CO{sub 3} intermediate mechanism and the Pt-Al{sup 3+} double sites mechanism. According to the calculated results analysis, we concluded that the dominant reaction pathway at the low temperatures is the reactive O*−O−C*=O intermediate mechanism. Our results are in very good agreement with the experimental evidence for O*−O−C*=O coverage on Pt/γ-Al{sub 2}O{sub 3} at room temperature by an in situ diffuse reflectance infrared detector.

  17. Single-cell mechanics--An experimental-computational method for quantifying the membrane-cytoskeleton elasticity of cells.

    Science.gov (United States)

    Tartibi, M; Liu, Y X; Liu, G-Y; Komvopoulos, K

    2015-11-01

    The membrane-cytoskeleton system plays a major role in cell adhesion, growth, migration, and differentiation. F-actin filaments, cross-linkers, binding proteins that bundle F-actin filaments to form the actin cytoskeleton, and integrins that connect the actin cytoskeleton network to the cell plasma membrane and extracellular matrix are major cytoskeleton constituents. Thus, the cell cytoskeleton is a complex composite that can assume different shapes. Atomic force microscopy (AFM)-based techniques have been used to measure cytoskeleton material properties without much attention to cell shape. A recently developed surface chemical patterning method for long-term single-cell culture was used to seed individual cells on circular patterns. A continuum-based cell model, which uses as input the force-displacement response obtained with a modified AFM setup and relates the membrane-cytoskeleton elastic behavior to the cell geometry, while treating all other subcellular components suspended in the cytoplasmic liquid (gel) as an incompressible fluid, is presented and validated by experimental results. The developed analytical-experimental methodology establishes a framework for quantifying the membrane-cytoskeleton elasticity of live cells. This capability may have immense implications in cell biology, particularly in studies seeking to establish correlations between membrane-cytoskeleton elasticity and cell disease, mortality, differentiation, and migration, and provide insight into cell infiltration through nonwoven fibrous scaffolds. The present method can be further extended to analyze membrane-cytoskeleton viscoelasticity, examine the role of other subcellular components (e.g., nucleus envelope) in cell elasticity, and elucidate the effects of mechanical stimuli on cell differentiation and motility. This is the first study to decouple the membrane-cytoskeleton elasticity from cell stiffness and introduce an effective approach for measuring the elastic modulus. The

  18. Watching single molecules dance

    Science.gov (United States)

    Mehta, Amit Dinesh

    Molecular motors convert chemical energy, from ATP hydrolysis or ion flow, into mechanical motion. A variety of increasingly precise mechanical probes have been developed to monitor and perturb these motors at the single molecule level. Several outstanding questions can be best approached at the single molecule level. These include: how far does a motor progress per energy quanta consumed? how does its reaction cycle respond to load? how many productive catalytic cycles can it undergo per diffusional encounter with its track? and what is the mechanical stiffness of a single molecule connection? A dual beam optical trap, in conjunction with in vitro ensemble motility assays, has been used to characterize two members of the myosin superfamily: muscle myosin II and chick brain myosin V. Both move the helical polymer actin, but myosin II acts in large ensembles to drive muscle contraction or cytokinesis, while myosin V acts in small numbers to transport vesicles. An optical trapping apparatus was rendered sufficiently precise to identify a myosin working stroke with 1nm or so, barring systematic errors such as those perhaps due to random protein orientations. This and other light microscopic motility assays were used to characterize myosin V: unlike myosin II this vesicle transport protein moves through many increments of travel while remaining strongly bound to a single actin filament. The step size, stall force, and travel distance of myosin V reveal a remarkably efficient motor capable of moving along a helical track for over a micrometer without significantly spiraling around it. Such properties are fully consistent with the putative role of an organelle transport motor, present in small numbers to maintain movement over long ranges relative to cellular size scales. The contrast between myosin II and myosin V resembles that between a human running on the moon and one walking on earth, where the former allows for faster motion when in larger ensembles but for less

  19. Translation effects on vertical Bridgman growth and optical, mechanical and surface analysis of 2-phenylphenol single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sadhasivam, S., E-mail: sadha.phy1@gmail.com [Department of Physics, Center for Crystal Growth, SSN College of Engineering, Tamil Nadu, India-603 110 (India); Perumal, Rajesh Narayana

    2016-05-06

    2-phenylphenol optical crystals were grown in cone ampoules using vertical Bridgman technique. Single crystal of 2-phenylphenol with 150 mm length has been grown. The inclination on the conical part of the ampoule reduces the growth defects in the 2-phenylphenol single crystal. The lattice parameters and structure studied using single crystal X-ray diffraction method. 2-phenylphenol single crystal belongs to orthorhombic space group Fdd2. The micro translation rate affects crystal growth of 2-phenylphenol crystal was studied. The translation rate dependent defects present in the crystal were investigated by transmittance, indentation and etching characterizations. The dislocation induced indentation crack lengths variations were studied. Etch pits and striations observed for the selective etchants furnish significant information on growth aspects and degree of defect present in the crystal.

  20. ACT Test

    Science.gov (United States)

    ... Content View Sources Ask Us Also Known As ACT Activated Coagulation Time Formal Name Activated Clotting Time ... What is being tested? The activated clotting time (ACT) is a test that is used primarily to ...

  1. Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds

    Science.gov (United States)

    Yang, Xiao; Li, Huijian; Hu, Minzheng; Liu, Zeliang; Wärnå, John; Cao, Yuying; Ahuja, Rajeev; Luo, Wei

    2018-04-01

    A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zrsbnd O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (ν) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

  2. From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials.

    Science.gov (United States)

    D'Amore, Antonio; Amoroso, Nicholas; Gottardi, Riccardo; Hobson, Christopher; Carruthers, Christopher; Watkins, Simon; Wagner, William R; Sacks, Michael S

    2014-11-01

    In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters adjusted to match the macro-level mechanical test data. Fiber model validation was performed at the microscopic level by individual fiber mechanical tests using AFM. Results demonstrated very good agreement to the experimental data, and revealed the formation of extended preferential fiber orientations spanning the entire model space. We speculate that these emergent structures may be responsible for the tissue-like macroscale behaviors observed in electrospun scaffolds. To conclude, the modeling approach has implications for (1) gaining insight on the intricate relationship between fabrication variables, structure, and mechanics to manufacture more functional devices/materials, (2) elucidating the effects of cell or particulate inclusions on global construct mechanics, and (3) fabricating better performing tissue surrogates that could recapitulate native tissue mechanics. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Preparation and characterization of functionalized single walled carbon nanotubes (fSWCNT)/ Hydroxyapatite (HAp)-Nylon hybridized composite biomaterial to study the mechanical properties

    Science.gov (United States)

    Khanal, Suraj; Leventouri, Theodora; Mahfuz, Hassan; Rondinone, Adam

    2014-03-01

    Synthetic hydroxyapatite (HAp) bears poor mechanical properties that limit its applicability in orthopedics. We study the possibility of overcoming such limitations by incorporating functionalized single walled carbon nanotubes (fSWCNT) in a biocompatible/bioactive nano-composite. We present results from synthesis and characterization of samples prepared under different processing parameters. Ultra sonication method was to disperse functionalized single walled carbon nanotubes (fSWCNT) in HAp followed by a simple hot assorting method to incorporate with polymerized ɛ-caprolactam. The fracture toughness of the composite materials was tested in compliance with the ASTM D-5045 standard. We have found that while the fracture toughness strongly depends on the processing parameters, a value comparable to the one for cortical bone is achieved. Mechanical properties, electron microscopy and crystal structure properties of the composite materials will be discussed.

  4. Human adipose tissue mesenchymal stromal cells and their extracellular vesicles act differentially on lung mechanics and inflammation in experimental allergic asthma.

    Science.gov (United States)

    de Castro, Ligia Lins; Xisto, Debora Gonçalves; Kitoko, Jamil Zola; Cruz, Fernanda Ferreira; Olsen, Priscilla Christina; Redondo, Patricia Albuquerque Garcia; Ferreira, Tatiana Paula Teixeira; Weiss, Daniel Jay; Martins, Marco Aurélio; Morales, Marcelo Marcos; Rocco, Patricia Rieken Macedo

    2017-06-24

    Asthma is a chronic inflammatory disease that can be difficult to treat due to its complex pathophysiology. Most current drugs focus on controlling the inflammatory process, but are unable to revert the changes of tissue remodeling. Human mesenchymal stromal cells (MSCs) are effective at reducing inflammation and tissue remodeling; nevertheless, no study has evaluated the therapeutic effects of extracellular vesicles (EVs) obtained from human adipose tissue-derived MSCs (AD-MSC) on established airway remodeling in experimental allergic asthma. C57BL/6 female mice were sensitized and challenged with ovalbumin (OVA). Control (CTRL) animals received saline solution using the same protocol. One day after the last challenge, each group received saline, 10 5 human AD-MSCs, or EVs (released by 10 5  AD-MSCs). Seven days after treatment, animals were anesthetized for lung function assessment and subsequently euthanized. Bronchoalveolar lavage fluid (BALF), lungs, thymus, and mediastinal lymph nodes were harvested for analysis of inflammation. Collagen fiber content of airways and lung parenchyma were also evaluated. In OVA animals, AD-MSCs and EVs acted differently on static lung elastance and on BALF regulatory T cells, CD3 + CD4 + T cells, and pro-inflammatory mediators (interleukin [IL]-4, IL-5, IL-13, and eotaxin), but similarly reduced eosinophils in lung tissue, collagen fiber content in airways and lung parenchyma, levels of transforming growth factor-β in lung tissue, and CD3 + CD4 + T cell counts in the thymus. No significant changes were observed in total cell count or percentage of CD3 + CD4 + T cells in the mediastinal lymph nodes. In this immunocompetent mouse model of allergic asthma, human AD-MSCs and EVs effectively reduced eosinophil counts in lung tissue and BALF and modulated airway remodeling, but their effects on T cells differed in lung and thymus. EVs may hold promise for asthma; however, further studies are required to elucidate the different

  5. [On improvement of the mechanism for establishing and changing indicators of quality and food safety in the regulatory and legal acts of the Eurasian Economical Union].

    Science.gov (United States)

    Arnautov, O V

    2016-01-01

    In accordance with the Treaty on the Eurasian Economic Union (EAEU) to ensure the sanitary and epidemiological welfare of the population within the Union, a coordinated policy in agreed policy in the sphere of application of sanitary measures is carried out. Sanitary measures are the obligatory requirements and procedures, including requirements for the final product, processing methods, production, transportation, storage and disposal, sampling procedures, methods of research (tests), risk assessment, the state registration, requirements for packaging directly aimed at ensuring the safety of products (goods) in order to protect human welfare, and they should be applied on the basis having a scientific explanation, and only to the extent that is necessary to protect human welfare. Sanitary measures applied within the Union should be based on international and regional standards, guidelines and (or) the recommendations, except when they based on appropriate scientific studies and explanations. In this case sanitary measures which could provide a higher level of sanitary protection are introduced. At present, the mechanism of the development, justification and approval of common sanitary and epidemiological requirements (ESR) and procedures of the Eurasian Economic Commission (the Commission) is not installed. The absence of a clear mechanism for the development, approval and implementation of the ESR to the products (goods) on the basis having a scientific explanation on the one hand could lead to the creation of unjustified barriers to foreign and mutual trade, on the other--to weaken the level of safety for human life and health of products (goods) placed on markets of the Union. In order to bring the regulatory legal acts of the Customs Union in accordance with the Treaty on the Eurasian Economic Union the Commission in cooperation with the competent authorities of the Member States in the field of sanitary and epidemiological welfare developed the project of

  6. Two-color spectroscopy of UV excited ssDNA complex with a single-wall nanotube probe: Fast nucleobase autoionization mechanism

    OpenAIRE

    Ignatova, Tetyana; Balaeff, Alexander; Zheng, Ming; Blades, Michael; Stoeckl, Peter; Rotkin, Slava V.

    2015-01-01

    DNA autoionization is a fundamental process wherein UV-photoexcited nucleobases dissipate energy by charge transfer to the environment without undergoing chemical damage. Here, single-wall carbon nanotubes (SWNT) are explored as a photoluminescent reporter for studying the mechanism and rates of DNA autoionization. Two-color photoluminescence spectroscopy allows separate photoexcitation of the DNA and the SWNTs in the UV and visible range, respectively. A strong SWNT photoluminescence quenchi...

  7. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  8. A Proof-of-Concept Clinical Trial of A Single Luteal Use of Long-Acting Gonadotropin-Releasing Hormone Antagonist Degarelix in Controlled Ovarian Stimulation for In Vitro Fertilization: Long Antagonist Protocol

    Directory of Open Access Journals (Sweden)

    Evangelos G. Papanikolaou

    2018-03-01

    Full Text Available IntroductionA drawback of gonadotropin-releasing hormone (GnRH antagonist protocols in in vitro fertilization (IVF is that they have limited flexibility in cycle programming. This proof of concept study explored the efficacy of a single-dose, long-acting GnRH antagonist IVF protocol. Trial registration number is NCT03240159, retrospectively registered on March 08, 2017.Materials and methodsThe efficacy of a single-dose long-acting antagonist, degarelix, was explored initially in healthy donors and subsequently in infertile patients. In the first part, five healthy oocyte donors underwent ovarian stimulation with this new protocol: in the late luteal phase, at day 24, a bolus injection of degarelix was administered subcutaneously to control the LH surge in the follicular phase. Ovarian stimulation with gonadotropins was initiated subsequently from day 7 to day 10. End points were first to inhibit the LH surge later in the follicular phase and, second, to retrieve mature oocytes for IVF. In the second part, five infertile women received the same bolus injection of degarelix administered during the luteal phase at day 24. Different gonadotropin starting days (day 2 through day 8 were tested in order to observe possible differences in ovarian stimulation. In these infertile patients, fresh embryo transfers were performed to assess the pregnancy efficacy of this protocol on pregnancy outcomes and to address any possible negative effects on endometrium receptivity.ResultsIn the first part of the study, all donors were effectively downregulated with a single luteal dose of 0.5 ml of degarelix for up to 22 days until the final oocyte maturation triggering day. Mature oocytes were retrieved after 36 h from all patients and all produced 2–7 blastocysts. In the second part, all five infertile patients achieved sufficient LH downregulation and completed ovarian stimulation without any LH surge. All patients (except one with freeze all strategy had

  9. Homogeneous and single-side-operational connector mechanism for self-reconfigurable, self-assembly and self-healing systems

    Science.gov (United States)

    Shen, Wei-Min (Inventor); Kovac, Robert M. (Inventor)

    2012-01-01

    Designs of single-end-operative reconfigurable genderless connectors that include a base, a plurality of movable jaws that are formed on the base and can engage to the jaws of another connector, and an actuator that is mounted on the base and can engage and move the jaws of the reconfigurable connector to connect the reconfigurable connector with another connector.

  10. Landing mechanics during single hop for distance in females following anterior cruciate ligament reconstruction compared to healthy controls.

    Science.gov (United States)

    Trigsted, Stephanie M; Post, Eric G; Bell, David R

    2017-05-01

    To determine possible differences in single-hop kinematics and kinetics in females with anterior cruciate ligament reconstruction compared to healthy controls. A second purpose was to make comparisons between the healthy and reconstructed limbs. Subjects were grouped based on surgical status (33 ACLR patients and 31 healthy controls). 3D motion capture synchronized with force plates was used to capture the landing phase of three successful trials of single hop for distance during a single data collection session. Peak values during the loading phase were analysed. Subjects additionally completed three successful trials of the triple hop for distance Tegner activity scale and International Knee Document Committee 2000 (IKDC). Controls demonstrated greater peak knee flexion and greater internal knee extension moment and hip extension moment than ACLR subjects. Within the ACLR group, the healthy limb exhibited greater peak knee flexion, hip flexion, hip extension moment, single hop and triple hops for distance and normalized quadriceps strength. Patients who undergo anterior cruciate ligament reconstruction land in a more extended posture when compared to healthy controls and compared to their healthy limb. III.

  11. A Polypeptide-DNA Hybrid with Selective Linking Capability Applied to Single Molecule Nano-Mechanical Measurements Using Optical Tweezers

    NARCIS (Netherlands)

    Moayed, F.; Mashaghi, A.; Tans, S.J.

    2013-01-01

    Many applications in biosensing, biomaterial engineering and single molecule biophysics require multiple non-covalent linkages between DNA, protein molecules, and surfaces that are specific yet strong. Here, we present a novel method to join proteins and dsDNA molecule at their ends, in an

  12. Highly parallel and short-acting amplification with locus-specific primers to detect single nucleotide polymorphisms by the DigiTag2 assay.

    Directory of Open Access Journals (Sweden)

    Nao Nishida

    Full Text Available The DigiTag2 assay enables analysis of a set of 96 SNPs using Kapa 2GFast HotStart DNA polymerase with a new protocol that has a total running time of about 7 hours, which is 6 hours shorter than the previous protocol. Quality parameters (conversion rate, call rate, reproducibility and concordance were at the same levels as when genotype calls were acquired using the previous protocol. Multiplex PCR with 192 pairs of locus-specific primers was available for target preparation in the DigiTag2 assay without the optimization of reaction conditions, and quality parameters had the same levels as those acquired with 96-plex PCR. The locus-specific primers were able to achieve sufficient (concentration of target amplicon ≥5 nM and specific (concentration of unexpected amplicons <2 nM amplification within 2 hours, were also able to achieve detectable amplifications even when working in a 96-plex or 192-plex form. The improved DigiTag2 assay will be an efficient platform for screening an intermediate number of SNPs (tens to hundreds of sites in the replication analysis after genome-wide association study. Moreover, highly parallel and short-acting amplification with locus-specific primers may thus facilitate widespread application to other PCR-based assays.

  13. Studies of the kinetics and mechanisms of ammonia synthesis and hydrodesulfurization on metal single-crystal surfaces

    International Nuclear Information System (INIS)

    Gellman, A.J.; Asscher, M.; Somorjai, G.A.

    1985-01-01

    The authors studied the ammonia synthesis reaction over Fe and Re single crystal surfaces and the hydrodesulfurization of thiophene over the Mo(100) single crystal surface. The studies have been performed using UHV surface science tools with the capability of exposing the surfaces to high pressure, high temperature reaction conditions. The ammonia synthesis reaction was shown to be extremely sensitive to surface structure on both Fe and Re, favoring surfaces with a rough or open topography. The HDS reaction on the Mo(100) surface has been shown to be similar to that on MoS/sub 2/ and appears to proceed via a reaction path that does not produce a strong Mo-S bond as an intermediate species

  14. The influnece of the partial single reduction on mechanical properties wires made from trip steel with 0,43 % C

    Directory of Open Access Journals (Sweden)

    S. Wiewiórowska

    2015-01-01

    Full Text Available Large strain inhomogeneity is caused by the shape of deformation zone of die and by the friction between tool and deformed wire for multistage wire drawing processes. The influence on the value of the redundant strain by the use of different partial single reductions during all wire drawing process was observed. This problem is particularly important for TRIP steel wires drawing processes because the strain intensity influences on the speed of retained austenite transformation into martensite.

  15. Surface growth mechanisms and structural faulting in the growth of large single and spherulitic titanosilicate ETS-4 crystals

    Science.gov (United States)

    Miraglia, Peter Q.; Yilmaz, Bilge; Warzywoda, Juliusz; Sacco, Albert

    2004-10-01

    Morphological, surface and crystallographic analyses of titanosilicate ETS-4 products, with diverse habits ranging from spherulitic particles composed of submicron crystallites to large single crystals, are presented. Pole figures revealed that crystal surfaces with a-, b- and c- axes corresponded to , and directions, respectively. Thus, technologically important 8-membered ring pores and titania chains in ETS-4 run along the b-axis of single crystals and terminate at the smallest crystal face. Height of the spiral growth steps observed on {1 0 0} and {0 0 1} surfaces corresponded to the interplanar spacings associated with their crystallographic orientation, and is equivalent to the thickness of building units that form the ETS-4 framework. Data suggest that the more viscous synthesis mixtures, with a large driving force for growth, increased the two- and three-dimensional nucleation, while limiting the transport of nutrients to the growth surface. These conditions increase the tendency for stacking fault formation on {1 0 0} surfaces and small angle branching, which eventually results in spherulitic growth. The growth of high quality ETS-4 single crystals (from less viscous synthesis mixtures) occurred at lower surface nucleation rates. Data suggest that these high quality, large crystals grew due to one-dimensional nucleation at spiral hillocks, and indicate that under these conditions un-faulted growth is preferred.

  16. Fluid balance and length of mechanical ventilation in children admitted to a single Pediatric Intensive Care Unit.

    Science.gov (United States)

    Vidal, Solange; Pérez, Augusto; Eulmesekian, Pablo

    2016-08-01

    Associations between cumulative fluid balance and a prolonged duration of assisted mechanical ventilation have been described in adults. The aim of this study was to evaluate whether fluid balance in the first 48 hours of assisted mechanical ventilation initiation was associated with a prolonged duration of this process among children in the Pediatric Intensive Care Unit (PICU). Retrospective cohort of patients in the PICU o, Hospital Italiano de Buenos Aires, between 1/1/2010 and 6/30/2012. Balance was calculated in percentage of body weight; prolonged mechanical ventilation was defined as >7 days, and confounders were registered. Univariate and multivariate analyses were performed. Two hundred and forty-nine patients were mechanically ventilated for over 48 hours; 163 were included in the study. Balance during the first 48 hours of mechanical ventilation was 5.7% ± 5.86; 82 patients (50.3%) were on mechanical ventilation for more than 7 days. Age 〈 4 years old (OR 3.21, 95% CI 1.38-7.48, p 0.007), respiratory disease (OR 4.94, 95% CI 1.51-16.10, p 0.008), septic shock (OR 4.66, 95% CI 1.10-19.65, p 0.036), Pediatric Logistic Organ Dysfunction (PELOD) 〉 10 (OR 2.44, 95% CI 1.234.85, p 0.011), and positive balance 〉 13% (OR 4.02, 95% CI 1.08-15.02, p 0.038) were associated with prolonged mechanical ventilation. The multivariate model resulted in an OR 2.58, 95% CI: 1.17-5.58, p= 0.018 for PELOD 〉 10, and an OR 3.7, 95% CI: 0.91-14.94, p= 0.066 for positive balance 〉 13%. Regarding prolonged mechanical ventilation, the multivariate model showed an independent association with organ dysfunction (PELOD 〉 10) and a trend towards an association with positive balance 〉 13%. Sociedad Argentina de Pediatría.

  17. Comparative Efficacy and Mechanisms of a Single-Session Pain Psychology Class in Chronic Low Back Pain: Study Protocol for a Randomized Controlled Trial.

    Science.gov (United States)

    Darnall, Beth D; Ziadni, Maisa S; Roy, Anuradha; Kao, Ming-Chih; Sturgeon, John A; Cook, Karon F; Lorig, Kate; Burns, John W; Mackey, Sean C

    2018-03-06

    The Institute of Medicine (IOM) reported that chronic pain affects about 100 million U.S. adults, with chronic low back pain (CLBP) cited as the most prevalent type. Pain catastrophizing is a psychological construct shown to predict the development and trajectory of chronic pain and patient response to pain treatments. While effective treatment for pain catastrophizing typically includes eight-session groups of cognitive behavioral therapy (CBT), a single-session targeted treatment class yielded promising results which, if replicated and extended, could prove to efficiently and cost-effectively reduce pain catastrophizing. In this trial, we seek to determine the comparative efficacy of this novel single-session pain catastrophizing class to an eight-session course of pain CBT and a single-session back pain health education class. We will also explore the psychosocial mechanisms and outcomes of pain catastrophizing treatment. In this trial we will randomize 231 individuals with CLBP to one of three treatment arms: (1) pain-CBT (eight weekly 2-h group sessions with home exercises and readings); (2) a single 2-h pain catastrophizing class; or (3) a single 2-h back pain health education class (active control). For the primary outcome of pain catastrophizing, the trial is designed as a non-inferiority test between pain-CBT and the single-session pain catastrophizing class, and as a superiority test between the single-session pain catastrophizing class and the health education class. Team researchers masked to treatment assignment will assess outcomes up to six months post treatment. If the single-session targeted pain catastrophizing class is found to be an effective treatment for patients with CLBP, this low cost and low burden treatment could dismantle many of the current barriers and burdens of effective pain care. Further, elucidation of the mechanisms of pain catastrophizing treatments will facilitate future research on the topic as well as further development and

  18. Single-molecule folding mechanisms of the apo- and Mg2+-bound states of human neuronal calcium sensor-1

    DEFF Research Database (Denmark)

    Naqvi, Mohsin M; Heiðarsson, Pétur Orri; Otazo, Mariela R

    2015-01-01

    Neuronal calcium sensor-1 (NCS-1) is the primordial member of a family of proteins responsible primarily for sensing changes in neuronal Ca(2+) concentration. NCS-1 is a multispecific protein interacting with a number of binding partners in both calcium-dependent and independent manners, and acting...... in a variety of cellular processes in which it has been linked to a number of disorders such as schizophrenia and autism. Despite extensive studies on the Ca(2+)-activated state of NCS proteins, little is known about the conformational dynamics of the Mg(2+)-bound and apo states, both of which are populated...... by populating one intermediate state consisting of a folded C-domain and an unfolded N-domain. The interconversion at equilibrium between the different molecular states populated by NCS-1 was monitored in real time through constant-force measurements and the energy landscapes underlying the observed transitions...

  19. Single-Molecule Titration in a Protein Nanoreactor Reveals the Protonation/Deprotonation Mechanism of a C:C Mismatch in DNA.

    Science.gov (United States)

    Ren, Hang; Cheyne, Cameron G; Fleming, Aaron M; Burrows, Cynthia J; White, Henry S

    2018-04-18

    Measurement of single-molecule reactions can elucidate microscopic mechanisms that are often hidden from ensemble analysis. Herein, we report the acid-base titration of a single DNA duplex confined within the wild-type α-hemolysin (α-HL) nanopore for up to 3 h, while monitoring the ionic current through the nanopore. Modulation between two states in the current-time trace for duplexes containing the C:C mismatch in proximity to the latch constriction of α-HL is attributed to the base flipping of the C:C mismatch. As the pH is lowered, the rate for the C:C mismatch to flip from the intra-helical state to the extra-helical state ( k intra-extra ) decreases, while the rate for base flipping from the extra-helical state to the intra-helical state ( k extra-intra ) remains unchanged. Both k intra-extra and k extra-intra are on the order of 1 × 10 -2 s -1 to 1 × 10 -1 s -1 and remain stable over the time scale of the measurement (several hours). Analysis of the pH-dependent kinetics of base flipping using a hidden Markov kinetic model demonstrates that protonation/deprotonation occurs while the base pair is in the intra-helical state. We also demonstrate that the rate of protonation is limited by transport of H + into the α-HL nanopore. Single-molecule kinetic isotope experiments exhibit a large kinetic isotope effect (KIE) for k intra-extra ( k H / k D ≈ 5) but a limited KIE for k extra-intra ( k H / k D ≈ 1.3), supporting our model. Our experiments correspond to the longest single-molecule measurements performed using a nanopore, and demonstrate its application in interrogating mechanisms of single-molecule reactions in confined geometries.

  20. H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts: Hydrothermal preparation and formation mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Chang, K.-H. [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621, Taiwan (China); Hu, C.-C. [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621, Taiwan (China)], E-mail: cchu@che.nthu.edu.tw

    2007-10-15

    The formation mechanism of highly pure H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts is clarified in a hydrothermal synthesis process with a specially designed precursor solution containing V{sup 5+} and V{sup 4+} in a fixed ratio of 2/1. This specially designed precursor solution provides an additional merit for the rapid fabrication of highly pure H{sub 2}V{sub 3}O{sub 8} nanobelts through a simple hydrothermal route. During the hydrothermal synthesis process, V{sup 5+} species initially reacts with some V{sup 4+} to form a metastable, whisker-like V{sub 10}O{sub 24} . nH{sub 2}O (n < 12). The V{sup 5+} species dissolved from the whisker-like V{sub 10}O{sub 24} . nH{sub 2}O reacts continuously with residual V{sup 4+} ions in the precursor solution to form seeds of H{sub 2}V{sub 3}O{sub 8} single-crystals. The anisotropic growth of H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts with length > 10 {mu}m and width between 50 and 150 nm occurs with prolonging the hydrothermal time. Finally, highly pure H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts are obtained when the hydrothermal time reaches 4 h. The textures of vanadium oxides prepared at different hydrothermal times are systematically compared through X-ray diffraction, transmission electron microscopic and X-ray photoelectron spectroscopic analyses to clarify the synthesis mechanism of H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts.

  1. Curatorial Acts

    NARCIS (Netherlands)

    Bal, M.

    2012-01-01

    In a self-critical inquiry into my own recent work of co-curating and the experience of seeing my video work being curated by others, this article examines acts of framing as performative acts that seek to transform visitors' preconceptions. This affective effect is pursued by means of immersion,

  2. Single-molecule tracking of small GTPase Rac1 uncovers spatial regulation of membrane translocation and mechanism for polarized signaling

    Science.gov (United States)

    Das, Sulagna; Yin, Taofei; Yang, Qingfen; Zhang, Jingqiao; Wu, Yi I.; Yu, Ji

    2015-01-01

    Polarized Rac1 signaling is a hallmark of many cellular functions, including cell adhesion, motility, and cell division. The two steps of Rac1 activation are its translocation to the plasma membrane and the exchange of nucleotide from GDP to GTP. It is, however, unclear whether these two processes are regulated independent of each other and what their respective roles are in polarization of Rac1 signaling. We designed a single-particle tracking (SPT) method to quantitatively analyze the kinetics of Rac1 membrane translocation in living cells. We found that the rate of Rac1 translocation was significantly elevated in protrusions during cell spreading on collagen. Furthermore, combining FRET sensor imaging with SPT measurements in the same cell, the recruitment of Rac1 was found to be polarized to an extent similar to that of the nucleotide exchange process. Statistical analysis of single-molecule trajectories and optogenetic manipulation of membrane lipids revealed that Rac1 membrane translocation precedes nucleotide exchange, and is governed primarily by interactions with phospholipids, particularly PI(3,4,5)P3, instead of protein factors. Overall, the study highlights the significance of membrane translocation in spatial Rac1 signaling, which is in addition to the traditional view focusing primarily on GEF distribution and exchange reaction. PMID:25561548

  3. The influence of cobalt, tantalum, and tungsten on the elevated temperature mechanical properties of single crystal nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1985-01-01

    The influence of composition on the tensile and creep strength of 001-line oriented nickel-base superalloy single crystals at temperatures near 1000 C was investigated. Cobalt, tantalum, and tungsten concentrations were varied according to a matrix of compositions based on the single crystal version of MAR-M247. For alloys with the baseline refractory metal level of 3 wt pct Ta and 10 wt pct W, decreases in Co level from 10 to 0 wt pct resulted in increased tensile and creep strength. Substitution of 2 wt pct W for 3 wt pct Ta resulted in decreased creep life at high stresses, but improved life at low stresses. Substitution of Ni for Ta caused large reductions in tensile strength and creep resistance, and corresponding increases in ductility. For these alloys with low Ta-plus-W totals, strength was independent of Co level. The effects of composition on properties were related to the microstructural features of the alloys. In general, high creep strength was associated with high levels of gamma-prime volume fraction, gamma-gamma-prime lattice mismatch, and solid solution hardening.

  4. The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation.

    Science.gov (United States)

    Ali, Sajjad; Fu Liu, Tian; Lian, Zan; Li, Bo; Sheng Su, Dang

    2017-08-23

    The mechanism of CO oxidation by O 2 on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory. We determine that single Au atoms can be trapped effectively by the defects on SWCNTs. The defects on SWCNTs can enhance both the binding strength and catalytic activity of the supported single Au atom. Fundamental aspects such as adsorption energy and charge transfer are elucidated to analyze the adsorption properties of CO and O 2 and co-adsorption of CO and O 2 molecules. It is found that CO binds stronger than O 2 on Au supported SWCNT. We clearly demonstrate that the defected SWCNT surface promotes electron transfer from the supported single Au atom to O 2 molecules. On the other hand, this effect is weaker for pristine SWCNTs. It is observed that the high density of spin-polarized states are localized in the region of the Fermi level due to the strong interactions between Au (5d orbital) and the adjacent carbon (2p orbital) atoms, which influence the catalytic performance. In addition, we elucidate both the Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms of CO oxidation by O 2 . For the LH pathway, the barriers of the rate-limiting step are calculated to be 0.02 eV and 0.05 eV for Au/m-SWCNT and Au/di-SWCNT, respectively. To regenerate the active sites, an ER-like reaction occurs to form a second CO 2 molecule. The ER pathway is observed on Au/m-SWCNT, Au/SW-SWCNT and Au/SWCNT in which the Au/m-SWCNT has a smaller barrier. The comparison with a previous study (Lu et al., J. Phys. Chem. C, 2009, 113, 20156-20160.) indicates that the curvature effect of SWCNTs is important for the catalytic property of the supported single Au. Overall, Au/m-SWCNT is identified as the most active catalyst for CO oxidation compared to pristine SWCNT, SW-SWCNT and di-SWCNT. Our findings give a

  5. The kink-pair mechanism and low-temperature flow-stress behaviour of strontium titanate single crystals

    International Nuclear Information System (INIS)

    Castillo-Rodriguez, M.; Sigle, W.

    2011-01-01

    The mechanical behaviour of strontium titanate exhibits a remarkable behaviour at low temperature, in the so-called regime A, where the flow stress experiences two different temperature dependences separated by a noticeably abrupt drop in between. The dislocation microstructure was investigated and, by making adequate use of the kink-pair model, we interpret this behaviour as a transition from the short- to the long-segment limit of kink-pair formation. The fit parameters are found to be physically sound.

  6. Depressurization and boiling of a single magmatic fluid as a mechanism for tin-tungsten deposit formation

    OpenAIRE

    Maximilian Korges; Philipp Weis; Volker Lüders; Oscar Laurent

    2018-01-01

    Tin (Sn) and tungsten (W) mineralization are commonly associated with each other in relation to highly evolved granites, but economical ore grades are restricted to rare global occurrences and mineralization styles are highly variable, indicating different mechanisms for ore formation. The Sn-W Zinnwald deposit in the Erzgebirge (Germany and the Czech Republic) in the roof zone of a Variscan Li-F granite hosts two contrasting styles of mineralization: (1) cassiterite (Sn) in greisen bodies, a...

  7. Measurement of the mechanical properties of single Synechocystis sp. strain PCC6803 cells in different osmotic concentrations using a robot-integrated microfluidic chip.

    Science.gov (United States)

    Chang, Di; Sakuma, Shinya; Kera, Kota; Uozumi, Nobuyuki; Arai, Fumihito

    2018-03-23

    Synechocystis sp. strain PCC6803 (Synechocystis) is a model microorganism and its mechanosensitive (MS) channels play important roles in its osmoadaptation mechanism. When the osmotic concentration of the culture environment changes, the inner pressure of the cell also changes due to the transportation of water through ion channels. Because the tension in the cell membrane relates to the inner pressure, we expect that the response of the MS channels to an osmotic concentration change could be evaluated by measuring their mechanical properties. Here, we propose a system for the measurement of the mechanical properties of a single Synechocystis cell. We developed a robot-integrated microfluidic chip combined with optical tweezers. The chip has an external actuated pushing probe and a force sensor probe. A single cell was located between the tip of both probes using the optical tweezers and was then deformed using the probes. As a result, we could measure the force and deformation and compare the Young's moduli of two groups: a group of wild type cells and a group of mutant (genetically modified) cells with a defect in the MS channels, at three different osmotic concentrations. The results showed that the Young's modulus of each group changed according to the osmotic concentration, while changes in cell size were too small to be detected. These results confirmed that the proposed evaluation method provides an understanding of the physiological function of MS channels for keeping the cell integrity of microorganisms when the cells are exposed to different external osmotic changes.

  8. Single nanowire electrode electrochemistry of silicon anode by in situ atomic force microscopy: solid electrolyte interphase growth and mechanical properties.

    Science.gov (United States)

    Liu, Xing-Rui; Deng, Xin; Liu, Ran-Ran; Yan, Hui-Juan; Guo, Yu-Guo; Wang, Dong; Wan, Li-Jun

    2014-11-26

    Silicon nanowires (SiNWs) have attracted great attention as promising anode materials for lithium ion batteries (LIBs) on account of their high capacity and improved cyclability compared with bulk silicon. The interface behavior, especially the solid electrolyte interphase (SEI), plays a significant role in the performance and stability of the electrodes. We report herein an in situ single nanowire atomic force microscopy (AFM) method to investigate the interface electrochemistry of silicon nanowire (SiNW) electrode. The morphology and Young's modulus of the individual SiNW anode surface during the SEI growth were quantitatively tracked. Three distinct stages of the SEI formation on the SiNW anode were observed. On the basis of the potential-dependent morphology and Young's modulus evolution of SEI, a mixture-packing structural model was proposed for the SEI film on SiNW anode.

  9. Dominant pinning mechanisms in YBa2Cu3O7-x films on single and polycrystalline yttria stabilized zirconia substrates

    Science.gov (United States)

    Harshavardhan, K. S.; Rajeswari, M.; Hwang, D. M.; Chen, C. Y.; Sands, T.; Venkatesan, T.; Tkaczyk, J. E.; Lay, K. W.; Safari, A.

    1992-04-01

    Critical-current densities have been measured in YBa2Cu3O7-x films deposited on (100) yttria stabilized zirconia (YSZ) and polycrystalline YSZ substrates as a function of temperature (4.5-88 K), magnetic field (0-1 T) and orientation relative to the applied field. The results indicate that in films on polycrystalline substrates, surface and interface pinning play a dominant role at high temperatures. In films on (100) YSZ, pinning is mainly due to intrinsic layer pinning as well as extrinsic pinning associated with the interaction of the fluxoids with point defects and low energy planar (2D) boundaries. The differences are attributed to the intrinsic rigidity of single fluxoids which is reduced in films on polycrystalline substrates thereby weakening the intrinsic layer pinning.

  10. Promoting mechanism of N-doped single-walled carbon nanotubes for O2 dissociation and SO2 oxidation

    Science.gov (United States)

    Chen, Yanqiu; Yin, Shi; Chen, Yang; Cen, Wanglai; Li, Jianjun; Yin, Huaqiang

    2018-03-01

    Although heteroatom doping in carbon based catalysts have recently received intensive attentions, the role of the intrinsically porous structure of practical carbon materials and their potential synergy with doping atoms are still unclear. To investigate the complex effects, a range of N-doped single-walled carbon nanotubes (SWCNTs) were used to investigate their potential use for O2 dissociation and the subsequent SO2 oxidation using density functional theory. It is found that graphite N doping can synergize with the outer surface of SWCNTs to facilitate the dissociation of O2. The barrier for the dissociation on dual graphite N-doped SWCNT-(8, 8) is as low as 0.3 eV, and the subsequent SO2 oxidation is thermodynamically favorable and kinetically feasible. These results spotlight on developing promising carboncatalyst via utilization of porous gemometry and heteroatom-doping of carbon materials simultaneously.

  11. Emergence of cytotoxic resistance in cancer cell populations: Single-cell mechanisms and population-level consequences

    International Nuclear Information System (INIS)

    Lorenzi, Tommaso; Chisholm, Rebecca H.; Lorz, Alexander; Neves de Almeida, Luís; Clairambault, Jean; Larsen, Annette K.; Escargueil, Alexandre

    2016-01-01

    We formulate an individual-based model and a population model of phenotypic evolution, under cytotoxic drugs, in a cancer cell population structured by the expression levels of survival-potential and proliferation-potential. We apply these models to a recently studied experimental system. Our results suggest that mechanisms based on fundamental laws of biology can reversibly push an actively-proliferating, and drug-sensitive, cell population to transition into a weakly-proliferative and drug-tolerant state, which will eventually facilitate the emergence of more potent, proliferating and drug-tolerant cells.

  12. Emergence of cytotoxic resistance in cancer cell populations: Single-cell mechanisms and population-level consequences

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzi, Tommaso [Centre de Mathématiques et de Leurs Applications, ENS Cachan, CNRS, Cachan 94230 Cedex, France & INRIA-Paris-Rocquencourt, MAMBA Team, Domaine de Voluceau, BP105, 78153 Le Chesnay Cedex (France); Chisholm, Rebecca H. [School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW 2052 (Australia); Lorz, Alexander; Neves de Almeida, Luís; Clairambault, Jean [Sorbonne Universités, UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); CNRS, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); INRIA-Paris-Rocquencourt, MAMBA Team, Domaine de Voluceau, BP105, 78153 Le Chesnay Cedex (France); Larsen, Annette K.; Escargueil, Alexandre [Sorbonne Universités, UPMC Univ Paris 06, F-75005, Paris (France); INSERM, UMR-S 938, Laboratory of “Cancer Biology and Therapeutics”, F-75012, Paris (France)

    2016-06-08

    We formulate an individual-based model and a population model of phenotypic evolution, under cytotoxic drugs, in a cancer cell population structured by the expression levels of survival-potential and proliferation-potential. We apply these models to a recently studied experimental system. Our results suggest that mechanisms based on fundamental laws of biology can reversibly push an actively-proliferating, and drug-sensitive, cell population to transition into a weakly-proliferative and drug-tolerant state, which will eventually facilitate the emergence of more potent, proliferating and drug-tolerant cells.

  13. Mechanical Control of Whole Body Shape by a Single Cuticular Protein Obstructor-E in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Reiko Tajiri

    2017-01-01

    Full Text Available Body shapes are much more variable than body plans. One way to alter body shapes independently of body plans would be to mechanically deform bodies. To what extent body shapes are regulated physically, or molecules involved in physical control of morphogenesis, remain elusive. During fly metamorphosis, the cuticle (exoskeleton covering the larval body contracts longitudinally and expands laterally to become the ellipsoidal pupal case (puparium. Here we show that Drosophila melanogaster Obstructor-E (Obst-E is a protein constituent of the larval cuticle that confers the oriented contractility/expandability. In the absence of obst-E function, the larval cuticle fails to undergo metamorphic shape change and finally becomes a twiggy puparium. We present results indicating that Obst-E regulates the arrangement of chitin, a long-chain polysaccharide and a central component of the insect cuticle, and directs the formation of supracellular ridges on the larval cuticle. We further show that Obst-E is locally required for the oriented shape change of the cuticle during metamorphosis, which is associated with changes in the morphology of those ridges. Thus, Obst-E dramatically affects the body shape in a direct, physical manner by controlling the mechanical property of the exoskeleton.

  14. Analysis of mechanical properties of N2in situ doped polycrystalline 3C-SiC thin films by chemical vapor deposition using single-precursor hexamethyildisilane

    International Nuclear Information System (INIS)

    Kim, Kang-San; Han, Ki-Bong; Chung, Gwiy-Sang

    2010-01-01

    This paper describes the mechanical properties of poly (polycrystalline) 3C-SiC thin films with N 2 in situ doping. In this work, in situ doped poly 3C-SiC film was deposited by using the atmospheric pressure chemical vapor deposition (APCVD) method at 1200 deg. C using single-precursor hexamethyildisilane: Si 2 (CH 3 ) 6 (HMDS) as Si and C precursors, and 0∼100 sccm N 2 as the dopant source gas. The mechanical properties of doped poly 3C-SiC thin films were measured by nano-indentation. Young's modulus and hardness were measured to be 285 and 35 GPa at 0 sccm N 2 , respectively. Young's modulus and hardness decreased with increasing N 2 flow rate. Surface morphology was evaluated by atomic force microscopy (AFM) according to N 2 flow rate.

  15. Balancing Acts

    Science.gov (United States)

    ... Past Issues Special Section: Focus on Communication Balancing Acts Past Issues / Fall 2008 Table of Contents For ... scientific research on hearing, balance, smell, taste, voice, speech, and language—common elements in how we perceive ...

  16. A microfluidic-enabled mechanical microcompressor for the immobilization of live single- and multi-cellular specimens.

    Science.gov (United States)

    Yan, Yingjun; Jiang, Liwei; Aufderheide, Karl J; Wright, Gus A; Terekhov, Alexander; Costa, Lino; Qin, Kevin; McCleery, W Tyler; Fellenstein, John J; Ustione, Alessandro; Robertson, J Brian; Johnson, Carl Hirschie; Piston, David W; Hutson, M Shane; Wikswo, John P; Hofmeister, William; Janetopoulos, Chris

    2014-02-01

    A microcompressor is a precision mechanical device that flattens and immobilizes living cells and small organisms for optical microscopy, allowing enhanced visualization of sub-cellular structures and organelles. We have developed an easily fabricated device, which can be equipped with microfluidics, permitting the addition of media or chemicals during observation. This device can be used on both upright and inverted microscopes. The apparatus permits micrometer precision flattening for nondestructive immobilization of specimens as small as a bacterium, while also accommodating larger specimens, such as Caenorhabditis elegans, for long-term observations. The compressor mount is removable and allows easy specimen addition and recovery for later observation. Several customized specimen beds can be incorporated into the base. To demonstrate the capabilities of the device, we have imaged numerous cellular events in several protozoan species, in yeast cells, and in Drosophila melanogaster embryos. We have been able to document previously unreported events, and also perform photobleaching experiments, in conjugating Tetrahymena thermophila.

  17. Single-Nucleotide Mutations in Reveal Novel Functions and Regulatory Mechanisms of the Fragile X Syndrome Protein FMRP

    Directory of Open Access Journals (Sweden)

    Joshua A. Suhl

    2015-01-01

    Full Text Available Fragile X syndrome is a monogenic disorder and a common cause of intellectual disability. Despite nearly 25 years of research on FMR1, the gene underlying the syndrome, very few pathological mutations other than the typical CGG-repeat expansion have been reported. This is in contrast to other X-linked, monogenic, intellectual disability disorders, such as Rett syndrome, where many point mutations have been validated as causative of the disorder. As technology has improved and significantly driven down the cost of sequencing, allowing for whole genes to be sequenced with relative ease, in-depth sequencing studies on FMR1 have recently been performed. These studies have led to the identification of novel variants in FMR1 , where some of which have been functionally evaluated and are likely pathogenic. In this review, we discuss recently identified FMR1 variants, the ways these novel variants cause dysfunction, and how they reveal new regulatory mechanisms and functionalities of the gene.

  18. Phase transformation mechanism in lithium manganese nickel oxide revealed by single-crystal hard X-ray microscopy

    Science.gov (United States)

    Kuppan, Saravanan; Xu, Yahong; Liu, Yijin; Chen, Guoying

    2017-02-01

    Understanding the reaction pathway and kinetics of solid-state phase transformation is critical in designing advanced electrode materials with better performance and stability. Despite the first-order phase transition with a large lattice mismatch between the involved phases, spinel LiMn1.5Ni0.5O4 is capable of fast rate even at large particle size, presenting an enigma yet to be understood. The present study uses advanced two-dimensional and three-dimensional nano-tomography on a series of well-formed LixMn1.5Ni0.5O4 (0growth process instead of a shrinking-core or a particle-by-particle process. Superior kinetics of (100) facets at the vertices of truncated octahedral particles promote preferential delithiation, whereas the observation of strain-induced cracking suggests mechanical degradation in the material.

  19. AN INVESTIGATION INTO THE MECHANICS OF SINGLE CRYSTAL TURBINE BLADES WITH A VIEW TOWARDS ENHANCING GAS TURBINE EFFICIENCY

    Energy Technology Data Exchange (ETDEWEB)

    K.R. Rajagopal; I.J. Rao

    2006-05-05

    The demand for increased efficiency of gas turbines used in power generation and aircraft applications has fueled research into advanced materials for gas turbine blades that can withstand higher temperatures in that they have excellent resistance to creep. The term ''Superalloys'' describes a group of alloys developed for applications that require high performance at elevated temperatures. Superalloys have a load bearing capacity up to 0.9 times their melting temperature. The objective of the investigation was to develop a thermodynamic model that can be used to describe the response of single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model. Having developed the model, its efficacy was to be tested by corroborating the predictions of the model with available experimental data. Such a model was developed and it is implemented in the finite element software ABAQUS/STANDARD through a user subroutine (UMAT) so that the model can be used in realistic geometries that correspond to turbine blades.

  20. Synthesis, growth, optical and anisotropic mechanical behaviour of organic nonlinear optical imidazolium 2-chloro-4-nitrobenzoate single crystals

    Science.gov (United States)

    Krishnakumar, Varadharajan; Jayaprakash, Jeyaram; Boobas, Singaram; Komathi, Muniraj

    2016-10-01

    The title compound, imidazolium 2-chloro-4-nitrobenzoate (I2C4NB), has been synthesized and optical quality single crystals were grown with a dimension of 4 × 2 × 1 mm3 using an ethanol and acetone (1:1) mixed solvent by slow evaporation solution growth technique. The powder XRD analysis confirmed the crystal structure and found that it is crystallized in the non-centrosymmetric space group P21 with the monoclinic system. The symmetries of molecular vibrations were confirmed by FT-IR spectrum. The CHN(S) analysis confirmed the stoichiometric composition of the grown crystal. It also exhibits a good transparency in the entire visible region (300-800nm) and it was thermally stable up to 131.1 °C. The microhardness measurement shows the anisotropic nature of I2C4NB and also that it belongs to a soft material category. Photoconductivity studies reveal a linear increase of the photocurrent with respect to the applied electric field. HOMO LUMO studies were carried out for the crystal. The second harmonic generation test by the Kurtz powder method shows that the crystal exhibits phase matching and a conversion efficiency which is 2 times that of KDP.

  1. Enhanced mechanical properties of single walled carbon nanotube-borosilicate glass composite due to cushioning effect and localized plastic flow

    Directory of Open Access Journals (Sweden)

    Sujan Ghosh

    2011-12-01

    Full Text Available A borosilicate glass composite has been fabricated incorporating Single Wall Carbon Nanotubes (SWCNT in the glass matrix by melt-quench technique. Hardness and the fracture toughness of the composite, were found to increase moderately with respect to the base glass. Interestingly one can observe accumulation of SWCNT bundles around the crack zone though no such accumulation was observed in the crack free indentation zone. The enhanced hardness of the composite was discussed by correlating the cushioning as well as toughening behavior of the agglomerated SWCNT bundles. On the other hand enhanced plastic flow was proposed to be the prime reason for the accumulation of SWCNT bundles around the crack, which increases the toughness of the composite by reducing the crack length. Moreover to ascertain the enhanced plasticity of the composite than that of the glass we calculated the recovery resistance of glass and the composite where recovery resistance of composite was found to be higher than that of the glass.

  2. Effect of single and multi-wall carbon nanotubes on the mechanical properties of Gd-123 superconducting phase

    Science.gov (United States)

    Anas, M.; Ebrahim, Shaker; Eldeen, I. G.; Awad, R.; Abou-Aly, A. I.

    2017-10-01

    The influence of single wall carbon nanotubes SWCNTs and multi wall carbon nanotubes MWCNTs on Vickers microhardness of Gd-123 superconducting phase is studied. Samples of type (SWCNTs)x and (MWCNTs)xGdBa2Cu3O7-δ, composite where, 0.0 ≤ x ≤ 0.1 wt.%, are prepared by solid-state reaction technique. The samples are characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM). Moreover the samples are examined by measuring electrical resistivity and Vickers microhardness. The obtained results showed an enhancement in the phase formation and grains connectivity up to 0.06 and 0.08 wt.% for SWCNTs and MWCNTs added samples, respectively. Likewise the superconducting transition temperature Tc was improved at a low content of CNTs but it suppressed for higher concentrations. In addition, the analysis of Vickers microhardness measurements suggests that the most suitable model that describes the behavior of our sample is proportional specimen resistance PSR model.

  3. Different mechanisms of radiation-induced loss of heterozygosity in two human lymphoid cell lines from a single donor

    Science.gov (United States)

    Wiese, C.; Gauny, S. S.; Liu, W. C.; Cherbonnel-Lasserre, C. L.; Kronenberg, A.

    2001-01-01

    Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis combined with microsatellite marker analysis showed that the increase in TK1 mutagenesis in WTK1 cells could be attributed, in part, to mitotic recombination. The microsatellite marker analysis over a 64-cM region on chromosome 17q indicated that the recombinational events could initiate at different positions between the TK1 locus and the centromere. Virtually all of the recombinational LOH events extended beyond the TK1 locus to the most telomeric marker. In general, longer LOH tracts were observed in mutants from WTK1 cells than in mutants from TK6 cells. Taken together, the results demonstrate that the incidence of radi-ation-induced mutations is dependent on the genetic background of the cell at risk, on the locus examined, and on the mechanisms for mutation available at the locus of interest.

  4. Mechanical performance of a screw-type veterinary suture anchor subjected to single load to failure and cyclic loads.

    Science.gov (United States)

    Balara, Jason M; McCarthy, Robert J; Boudrieau, Randy J; Kraus, Karl H

    2004-01-01

    To characterize the mechanical performance of a veterinary bone anchor under static and cyclic loads. Mechanical testing study. Cadaveric canine humeri. Humeri (6 pairs) were collected from skeletally mature dogs (mean [+/-SD] age, 17.2+/-2.1 months; weight, 20.8+/-1.5 kg). Bone anchors were inserted in the proximal metaphysis using nylon, and were longitudinally extracted. For the opposite humerus, anchors were subjected to longitudinal cyclic load (50% of the load at failure of their pair) for 1200 cycles then longitudinally loaded to failure. Anchors were then installed in a similar and adjacent area of these 2(nd) humeri with nylon and cyclically tested perpendicular to the axis of anchor insertion (100% of the longitudinal holding power of their pair) for 1200 cycles, then perpendicularly loaded to failure. Paired t-tests were used to compare holding power before and after longitudinal cyclic testing. Longitudinal holding power of the screw-type anchor in the proximal humerus was 385+/-30 N. Anchor pullout was the only mode of failure. Anchors in the paired humeri did not fail after 1200 cycles of 50% longitudinal loading, and post-cycle holding strength was not different (335+/-87 N; P=.32). Perpendicularly loaded anchors did not fail after 1200 cycles of 100% of opposite longitudinal holding strength, and had post-cycle perpendicular holding strengths of 514+/-72 N. Suture breakage was the mode of failure. Bone anchor holding strength is dependent on orientation of suture load. Screw-type bone anchor holding strength was not affected by longitudinal cyclic loading, and holding strengths of approximately 385 N can be expected in metaphyseal bone of large-breed mature dogs. Perpendicularly loaded anchors have higher failure loads, and holding strength of approximately 514 N can be expected in metaphyseal bone of the proximal humerus.

  5. Molecular beam study of the mechanism of catalyzed hydrogen--deuterium exchange on platinum single crystal surfaces

    International Nuclear Information System (INIS)

    Bernasek, S.L.; Somorjai, G.A.

    1975-01-01

    The hydrogen--deuterium exchange reaction was studied by molecular beam scattering on low and high Miller index crystal faces of platinum in the surface temperature range of 300--1300degreeK. Under the condition of the experiments which put strict limitation on the residence time of the detected molecules, the reaction product, HD, was readily detectable from the high Miller index, stepped surfaces (integrated reaction probability, defined as total desorbed HD flux divided by D 2 flux, is approx.10/sup -1/) while HD formation was below the limit of detectability on the Pt(111) low Miller index surface (reaction probability 2 beam pressure and half-order in H 2 background pressure. The absence of beam kinetic energy dependence of the rate indicates that the molecular adsorption does not require activation energy. The surface is able to store a sufficiently large concentration of atoms which react with the molecules by a two-branch mechanism. The rate constants for this two-branch mechanism were determined under conditions of constant H atom coverage, reducing the bimolecular reaction to a pseudo-first-order reaction. At lower temperatures ( 1 = (2plus-or-minus1) times10 5 exp(-4.5plus-or-minus0.5 kcal/RT) sec/sup -1/. The rate determining step appears to be the diffusion of the D 2 molecule on the surface to a step site where HD is formed via a three-center (atom--molecule) reaction, or via a two-center (atom--atom) reaction subsequent to D 2 dissociation at the step. At higher temperatures (>600degreeK) the reaction between an adsorbed H atom and an incident D 2 gas molecule competes with the low temperature branch. The rate constant for this branch is k 2 = (1plus-or-minus2) times10 2 exp(-0.6plus-or-minus0.3 kcal/RT) sec/sup -1/

  6. Altered lower extremity joint mechanics occur during the star excursion balance test and single leg hop after ACL-reconstruction in a collegiate athlete.

    Science.gov (United States)

    Samaan, Michael A; Ringleb, Stacie I; Bawab, Sebastian Y; Greska, Eric K; Weinhandl, Joshua T

    2018-03-15

    The effects of ACL-reconstruction on lower extremity joint mechanics during performance of the Star Excursion Balance Test (SEBT) and Single Leg Hop (SLH) are limited. The purpose of this study was to determine if altered lower extremity mechanics occur during the SEBT and SLH after ACL-reconstruction. One female Division I collegiate athlete performed the SEBT and SLH tasks, bilaterally, both before ACL injury and 27 months after ACL-reconstruction. Maximal reach, hop distances, lower extremity joint kinematics and moments were compared between both time points. Musculoskeletal simulations were used to assess muscle force production during the SEBT and SLH at both time points. Compared to the pre-injury time point, SEBT reach distances were similar in both limbs after ACL-reconstruction except for the max anterior reach distance in the ipsilateral limb. The athlete demonstrated similar hop distances, bilaterally, after ACL-reconstruction compared to the pre-injury time point. Despite normal functional performance during the SEBT and SLH, the athlete exhibited altered lower extremity joint mechanics during both of these tasks. These results suggest that measuring the maximal reach and hop distances for these tasks, in combination with an analysis of the lower extremity joint mechanics that occur after ACL-reconstruction, may help clinicians and researchers to better understand the effects of ACL-reconstruction on the neuromuscular system during the SEBT and SLH.

  7. Time-Dependent Mechanical Response of APbX3 (A = Cs, CH3NH3; X = I, Br) Single Crystals

    KAUST Repository

    Reyes-Martinez, Marcos A.

    2017-05-02

    The ease of processing hybrid organic-inorganic perovskite (HOIPs) films, belonging to a material class with composition ABX3 , from solution and at mild temperatures promises their use in deformable technologies, including flexible photovoltaic devices, sensors, and displays. To successfully apply these materials in deformable devices, knowledge of their mechanical response to dynamic strain is necessary. The authors elucidate the time- and rate-dependent mechanical properties of HOIPs and an inorganic perovskite (IP) single crystal by measuring nanoindentation creep and stress relaxation. The observation of pop-in events and slip bands on the surface of the indented crystals demonstrate dislocation-mediated plastic deformation. The magnitudes of creep and relaxation of both HOIPs and IPs are similar, negating prior hypothesis that the presence of organic A-site cations alters the mechanical response of these materials. Moreover, these samples exhibit a pronounced increase in creep, and stress relaxation as a function of indentation rate whose magnitudes reflect differences in the rates of nucleation and propagation of dislocations within the crystal structures of HOIPs and IP. This contribution provides understanding that is critical for designing perovskite devices capable of withstanding mechanical deformations.

  8. Levels of reflective thinking and patient safety: an investigation of the mechanisms that impact on student learning in a single cohort over a 5 year curriculum.

    Science.gov (United States)

    Ambrose, Lucy J; Ker, Jean S

    2014-08-01

    Existing research into learning about patient safety focuses on identifying how educational interventions improve educational outcomes but few studies offer evidence that inform educators about the mechanisms involved in learning about patient safety. The current evidence based in undergraduates is also limited to outcomes that relate to knowledge and skills. A realist approach involving three cycles of data collection in a single cohort of students over 5 years used different outcomes in Kirkpatrick's framework to identify the mechanisms that influence students learning about patient safety. Data source 1. Focus groups identified an overarching theoretical model of the mechanisms that influence patient safety learning for medical students. Data source 2 Identified if the mechanisms from data source 1 could be demonstrated at the outcome level of knowledge and attitudes. Data source 3 Established associations between mechanisms and outcomes at skills and behavioural level, in a standardised simulated ward setting. Data source 1: The interpretation of data from seven focus groups involving sixty students identified reflection at two levels of Mezirow's descriptions; reflection and critical reflection as mechanisms that influence learning about error. Data source 2: Sixty-one students participated. The associations found, reflection and knowledge of actions to take for patient safety, r = 0.44 (P = 0.00) and critical reflection and intentions regarding patient safety, r = 0.40 (P = 0.00) Data source 3: Forty-eight students participated. The correlation identified associations between critical reflection and planned changes following feedback was, r = 0.48 (P = 0.00) and reflection and knowledge based errors r = -0.30 (P = 0.03). A realist approach identified two different levels of reflection were associated with different patient safety outcomes for this cohort of students. Critical reflection was associated with attitudes and reflection was associated with

  9. Single-asperity contact mechanics with positive and negative work of adhesion: Influence of finite-range interactions and a continuum description for the squeeze-out of wetting fluids.

    Science.gov (United States)

    Müser, Martin H

    2014-01-01

    In this work, single-asperity contact mechanics is investigated for positive and negative work of adhesion Δγ. In the latter case, finite-range repulsion acts in addition to hard-wall constraints. This constitutes a continuum model for a contact immersed in a strongly wetting fluid, which can only be squeezed out in the center of the contact through a sufficiently large normal load F N. As for positive work of adhesion, two stable solutions can coexist in a finite range of normal loads. The competing solutions can be readily interpreted as contacts with either a load-bearing or a squeezed-out fluid. The possibility for coexistence and the subsequent discontinuous wetting and squeeze-out instabilities depend not only on the Tabor coefficient μT but also on the functional form of the finite-range repulsion. For example, coexistence and discontinuous wetting or squeeze-out do not occur when the repulsion decreases exponentially with distance. For positive work of adhesion, the normal displacement mainly depends on F N, Δγ, and μT but - unlike the contact area - barely on the functional form of the finite-range attraction. The results can benefit the interpretation of atomic force microscopy in liquid environments and the modeling of multi-asperity contacts.

  10. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    International Nuclear Information System (INIS)

    Wei, Pei; Wei, Zhengying; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-01-01

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  11. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Pei; Wei, Zhengying, E-mail: zywei@mail.xjtu.edu.cn; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-06-30

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  12. Mechanism of adsorption of single and double stranded DNA on gold and silver nanoparticles: Investigating some important parameters in bio-sensing applications.

    Science.gov (United States)

    Farkhari, Nahid; Abbasian, Sara; Moshaii, Ahmad; Nikkhah, Maryam

    2016-12-01

    The mechanism of adsorption of single and double stranded DNAs on colloidal gold and silver nanoparticles has been studied by measuring the resistance of the nanoparticles, surrounded by various oligonucleotides, against salt induced aggregation. It is shown that both single and double stranded DNAs can be adsorbed on the metal nanoparticles and the adsorption strength is determined by the interaction between various bases of DNA and the nanoparticles. By changing the salt concentration, the difference between adsorption of various DNA strands on the nanoparticles can be specified. The results indicate that a key parameter in success of a sensing assay of DNA hybridization is the salt concentration which should be greater than a minimum threshold depending on the nanoparticles characteristics. We have also investigated the interaction mechanism between various DNA bases with the metal nanoparticles. For both gold and silver nanoparticles, adenine has the highest and thymine has the lowest attachment to the nanoparticles. From surface enhanced Raman spectroscopy (SERS) data of various bases in the presence of gold nanoparticles, the probable interaction points in the bases with the nanoparticles have been determined, which are mainly the nitrogen sites of these oligonucleotides. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Real-time single-molecule tethered particle motion experiments reveal the kinetics and mechanisms of Cre-mediated site-specific recombination

    Science.gov (United States)

    Fan, Hsiu-Fang

    2012-01-01

    Tyrosine family recombinases (YRs) are widely utilized in genome engineering systems because they can easily direct DNA rearrangement. Cre recombinases, one of the most commonly used types of YRs, catalyze site-specific recombination between two loxP sites without the need for high-energy cofactors, other accessory proteins or a specific DNA target sequence between the loxP sites. Previous structural, analytical ultracentrifuge and electrophoretic analyses have provided details of the reaction kinetics and mechanisms of Cre recombinase activity; whether there are reaction intermediates or side pathways involved has been left unaddressed. Using tethered particle motion (TPM), the Cre-mediated site-specific recombination process has been delineated, from beginning to end, at the single-molecule level, including the formation of abortive complexes and wayward complexes blocking inactive nucleoprotein complexes from entering the recombination process. Reversibility in the strand-cleavage/-ligation process and the formation of a thermally stable Holliday junction intermediate were observed within the Cre-mediated site-specific recombination process. Rate constants for each elementary step, which explain the overall reaction outcomes under various conditions, were determined. Taking the findings of this study together, they demonstrate the potential of single-molecule methodology as an alternative approach for exploring reaction mechanisms in detail. PMID:22467208

  14. Angle dependence on the anisotropic magnetoresistance amplitude of a single-contacted Ni nanowire subjected to a thermo-mechanical strain

    Energy Technology Data Exchange (ETDEWEB)

    Melilli, G.; Madon, B.; Wegrowe, J.-E., E-mail: jean-eric.wegrowe@polytechnique.edu; Clochard, M.-C., E-mail: clochard@cea.fr

    2015-12-15

    The effects of thermoelastic and piezoelectric strain of an active track-etched β-PVDF polymer matrix on an electrodeposited single-contacted Ni nanowire (NW) are investigated at the nanoscale by measuring the change of magnetization (i.e. using the inverse magnetostriction effect). The magnetization state is measured locally by anisotropic magnetoresistance (AMR). The ferromagnetic NW plays thus the role of a mechanical probe that allows the effects of mechanical strain to be characterized and described qualitatively and quantitatively. The inverse magnetostriction was found to be responsible for a quasi-disappearance of the AMR signal for a variation of the order of ΔT ≈ 10 K. In other terms, the variation of the magnetization due to the stress compensates the effect of external magnetic field applied on the NW resistance. The induced stress field in a single Ni NW was found 1000 time higher than the bulk stress field (due to thermal expansion measured on the PVDF). This amplification could be attributed to three nanoscopic effects: (1) a stress mismatch between the Ni NW and the membrane, (2) a non-negligible role of the surface tension on Ni NW Young modulus, and (3) the possibility of non-linear stress–strain law. We investigate here the role of these different contributions using track-etched polymer membranes irradiated at various angles (α{sub irrad}) leading to, after electrodeposition, embedded Ni NWs of different orientations.

  15. Angle dependence on the anisotropic magnetoresistance amplitude of a single-contacted Ni nanowire subjected to a thermo-mechanical strain

    Science.gov (United States)

    Melilli, G.; Madon, B.; Wegrowe, J.-E.; Clochard, M.-C.

    2015-12-01

    The effects of thermoelastic and piezoelectric strain of an active track-etched β-PVDF polymer matrix on an electrodeposited single-contacted Ni nanowire (NW) are investigated at the nanoscale by measuring the change of magnetization (i.e. using the inverse magnetostriction effect). The magnetization state is measured locally by anisotropic magnetoresistance (AMR). The ferromagnetic NW plays thus the role of a mechanical probe that allows the effects of mechanical strain to be characterized and described qualitatively and quantitatively. The inverse magnetostriction was found to be responsible for a quasi-disappearance of the AMR signal for a variation of the order of ΔT ≈ 10 K. In other terms, the variation of the magnetization due to the stress compensates the effect of external magnetic field applied on the NW resistance. The induced stress field in a single Ni NW was found 1000 time higher than the bulk stress field (due to thermal expansion measured on the PVDF). This amplification could be attributed to three nanoscopic effects: (1) a stress mismatch between the Ni NW and the membrane, (2) a non-negligible role of the surface tension on Ni NW Young modulus, and (3) the possibility of non-linear stress-strain law. We investigate here the role of these different contributions using track-etched polymer membranes irradiated at various angles (αirrad) leading to, after electrodeposition, embedded Ni NWs of different orientations.

  16. Angle dependence on the anisotropic magnetoresistance amplitude of a single-contacted Ni nanowire subjected to a thermo-mechanical strain

    International Nuclear Information System (INIS)

    Melilli, G.; Madon, B.; Wegrowe, J.-E.; Clochard, M.-C.

    2015-01-01

    The effects of thermoelastic and piezoelectric strain of an active track-etched β-PVDF polymer matrix on an electrodeposited single-contacted Ni nanowire (NW) are investigated at the nanoscale by measuring the change of magnetization (i.e. using the inverse magnetostriction effect). The magnetization state is measured locally by anisotropic magnetoresistance (AMR). The ferromagnetic NW plays thus the role of a mechanical probe that allows the effects of mechanical strain to be characterized and described qualitatively and quantitatively. The inverse magnetostriction was found to be responsible for a quasi-disappearance of the AMR signal for a variation of the order of ΔT ≈ 10 K. In other terms, the variation of the magnetization due to the stress compensates the effect of external magnetic field applied on the NW resistance. The induced stress field in a single Ni NW was found 1000 time higher than the bulk stress field (due to thermal expansion measured on the PVDF). This amplification could be attributed to three nanoscopic effects: (1) a stress mismatch between the Ni NW and the membrane, (2) a non-negligible role of the surface tension on Ni NW Young modulus, and (3) the possibility of non-linear stress–strain law. We investigate here the role of these different contributions using track-etched polymer membranes irradiated at various angles (α irrad ) leading to, after electrodeposition, embedded Ni NWs of different orientations.

  17. Single-molecule supercoil-relaxation assay as a screening tool to determine the mechanism and efficacy of human topoisomerase IB inhibitors

    Science.gov (United States)

    Seol, Yeonee; Zhang, Hongliang; Agama, Keli; Lorence, Nicholas; Pommier, Yves; Neuman, Keir C.

    2015-01-01

    Human nuclear type IB topoisomerase (Top1) inhibitors are widely used and powerful anti-cancer agents. In this study, we introduce and validate a single-molecule supercoil relaxation assay as a molecular pharmacology tool for characterizing therapeutically relevant Top1 inhibitors. Using this assay, we determined the effects on Top1 supercoil relaxation activity of four Top1 inhibitors; three clinically relevant: camptothecin, LMP-400, LMP-776 (both indenoisoquinoline derivatives), and one natural product in preclinical development, lamellarin-D. Our results demonstrate that Top1 inhibitors have two distinct effects on Top1 activity: a decrease in supercoil relaxation rate and an increase in religation inhibition. The type and magnitude of the inhibition mode depend both on the specific inhibitor and on the topology of the DNA substrate. In general, the efficacy of inhibition is significantly higher with supercoiled than with relaxed DNA substrates. Comparing single-molecule inhibition with cell growth inhibition (IC50) measurements showed a correlation between the binding time of the Top1 inhibitors and their cytotoxic efficacy, independent of the mode of inhibition. This study demonstrates that the single-molecule supercoil relaxation assay is a sensitive method to elucidate the detailed mechanisms of Top1 inhibitors and is relevant for the cellular efficacy of Top1 inhibitors. PMID:26351326

  18. Sorption mechanisms of phenanthrene, lindane, and atrazine with various humic acid fractions from a single soil sample.

    Science.gov (United States)

    Wang, Xilong; Guo, Xiaoying; Yang, Yu; Tao, Shu; Xing, Baoshan

    2011-03-15

    The sorption behavior of organic compounds (phenanthrene, lindane, and atrazine) to sequentially extracted humic acids and humin from a peat soil was examined. The elemental composition, XPS and (13)C NMR data of sorbents combined with sorption isotherm data of the tested compounds show that nonspecific interactions govern sorption of phenanthrene and lindane by humic substances. Their sorption is dependent on surface and bulk alkyl carbon contents of the sorbents, rather than aromatic carbon. Sorption of atrazine by these sorbents, however, is regulated by polar interactions (e.g., hydrogen bonding). Carboxylic and phenolic moieties are key components for H-bonding formation. Thermal analysis reveals that sorption of apolar (i.e., phenanthrene and lindane) and polar (i.e., atrazine) compounds by humic substances exhibit dissimilar relationships with condensation and thermal stability of sorption domains, emphasizing the major influence of domain spatial arrangement on sorption of organic compounds with distinct polarity. Results of pH-dependent sorption indicate that reduction in sorption of atrazine by the tested sorbents is more evident than phenanthrene with increasing pH, supporting the dependence of organic compound sorption on its polarity and structure. This study highlights the different interaction mechanisms of apolar and polar organic compounds with humic substances.

  19. A computational chemistry study on friction of h-MoS(2). Part I. Mechanism of single sheet lubrication.

    Science.gov (United States)

    Onodera, Tasuku; Morita, Yusuke; Suzuki, Ai; Koyama, Michihisa; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Dassenoy, Fabrice; Minfray, Clotilde; Joly-Pottuz, Lucile; Martin, Jean-Michel; Miyamoto, Akira

    2009-12-31

    In this work, we theoretically investigated the friction mechanism of hexagonal MoS(2) (a well-known lamellar compound) using a computational chemistry method. First, we determined several parameters for molecular dynamics simulations via accurate quantum chemistry calculations and MoS(2) and MoS(2-x)O(x) structures were successfully reproduced. We also show that the simulated Raman spectrum and peak shift on X-ray diffraction patterns were in good agreement with those of experiment. The atomic interactions between MoS(2) sheets were studied by using a hybrid quantum chemical/classical molecular dynamics method. We found that the predominant interaction between two sulfur layers in different MoS(2) sheets was Coulombic repulsion, which directly affects the MoS(2) lubrication. MoS(2) sheets adsorbed on a nascent iron substrate reduced friction further due to much larger Coulombic repulsive interactions. Friction for the oxygen-containing MoS(2) sheets was influenced by not only the Coulomb repulsive interaction but also the atomic-scale roughness of the MoS(2)/MoS(2) sliding interface.

  20. Keep focussing: striatal dopamine multiple functions resolved in a single mechanism tested in a simulated humanoid robot

    Directory of Open Access Journals (Sweden)

    Vincenzo G. Fiore

    2014-02-01

    Full Text Available The effects of striatal dopamine (DA on behavior have been widely investigated over the past decades, with ``phasic'' burst firings considered as the key expression of a reward prediction error responsible for reinforcement learning. Less well studied is tonic DA, where putative functions include the idea that it is a regulator of vigor, incentive salience, disposition to exert an effort and a modulator of approach strategies. We present a preliminary model combining tonic and phasic DA to show how different outflows triggered by either intrinsically or extrinsically motivating stimuli dynamically affect the basal ganglia by impacting on a selection process that this system performs on the inputs provided by the targeted cortex.The model, which has been tested on the simulated humanoid robot iCub in the interaction with a mechatronic board, shows the putative functions ascribed to DA emerging from the combination of a standard computational mechanism coupled to a differential sensitivity to the presence of DA across the striatum.

  1. The Parkinsonian Gait Spatiotemporal Parameters Quantified by a Single Inertial Sensor before and after Automated Mechanical Peripheral Stimulation Treatment

    Directory of Open Access Journals (Sweden)

    Ana Kleiner

    2015-01-01

    Full Text Available This study aims to evaluate the change in gait spatiotemporal parameters in subjects with Parkinson’s disease (PD before and after Automated Mechanical Peripheral Stimulation (AMPS treatment. Thirty-five subjects with PD and 35 healthy age-matched subjects took part in this study. A dedicated medical device (Gondola was used to administer the AMPS. All patients with PD were treated in off levodopa phase and their gait performances were evaluated by an inertial measurement system before and after the intervention. The one-way ANOVA for repeated measures was performed to assess the differences between pre- and post-AMPS and the one-way ANOVA to assess the differences between PD patients and the control group. Spearman’s correlations assessed the associations between patients with PD clinical status (H&Y and the percentage of improvement of the gait variables after AMPS (α<0.05 for all tests. The PD group had an improvement of 14.85% in the stride length; 14.77% in the gait velocity; and 29.91% in the gait propulsion. The correlation results showed that the higher the H&Y classification, the higher the stride length percentage of improvement. The treatment based on AMPS intervention seems to induce a better performance in the gait pattern of PD patients, mainly in intermediate and advanced stages of the condition.

  2. Single-molecule magnetism in three related {Co(III)2Dy(III)2}-acetylacetonate complexes with multiple relaxation mechanisms.

    Science.gov (United States)

    Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S

    2013-06-17

    Three new heterometallic complexes with formulas of [Dy(III)2Co(III)2(OMe)2(teaH)2(acac)4(NO3)2] (1), [Dy(III)2Co(III)2(OH)2(teaH)2(acac)4(NO3)2]·4H2O (2), and [Dy(III)2Co(III)2(OMe)2(mdea)2(acac)4(NO3)2] (3) were characterized by single-crystal X-ray diffraction and by dc and ac magnetic susceptibility measurements. All three complexes have an identical "butterfly"-type metallic core that consists of two Dy(III) ions occupying the "body" position and two diamagnetic low-spin Co(III) ions occupying the outer "wing-tips". Each complex displays single-molecule magnet (SMM) behavior in zero applied magnetic field, with thermally activated anisotropy barriers of 27, 28, and 38 K above 7.5 K for 1-3, respectively, as well as observing a temperature-independent mechanism of relaxation below 5 K for 1 and 2 and at 3 K for 3, indicating fast quantum tunneling of magnetization (QTM). A second, faster thermally activated relaxation mechanism may also be active under a zero applied dc field as derived from the Cole-Cole data. Interestingly, these complexes demonstrate further relaxation modes that are strongly dependent upon the application of a static dc magnetic field. Dilution experiments that were performed on 1, in the {Y(III)2Co(III)2} diamagnetic analog, show that the slow magnetic relaxation is of a single-ion origin, but it was found that the neighboring ion also plays an important role in the overall relaxation dynamics.

  3. Co-lateralized bilingual mechanisms for reading in single and dual language contexts: evidence from visual half-field processing of action words in proficient bilinguals

    Directory of Open Access Journals (Sweden)

    Marlena eKrefta

    2015-08-01

    Full Text Available When reading, proficient bilinguals seem to engage the same cognitive circuits regardless of the language in use. Yet, whether or not such ‘bilingual’ mechanisms would be lateralized in the same way in distinct – single or dual – language contexts is a question for debate. To fill this gap, we tested 18 highly proficient Polish (L1 – English (L2 childhood bilinguals whose task was to read aloud one of the two laterally presented action verbs, one stimulus per visual half field. While in the single-language blocks only L1 or L2 words were shown, in the subsequent mixed-language blocks words from both languages were concurrently displayed. All stimuli were presented for 217 ms followed by masks in which letters were replaced with hash marks. Since in non-simultaneous bilinguals the control of language, skilled actions (including reading, and representations of action concepts are typically left lateralized, the vast majority of our participants showed the expected, significant right visual field advantage for L1 and L2, both for accuracy and response times. The observed effects were nevertheless associated with substantial variability in the strength of the lateralization of the mechanisms involved. Moreover, although it could be predicted that participants’ performance should be better in a single-language context, accuracy was significantly higher and response times were significantly shorter in a dual-language context, irrespective of the language tested. Finally, for both accuracy and response times, there were significant positive correlations between the laterality indices (LIs of both languages independent of the context, with a significantly greater left-sided advantage for L1 vs. L2 in the mixed-language blocks, based on LIs calculated for response times. Thus, despite similar representations of the two languages in the bilingual brain, these results also point to the functional separation of L1 and L2 in the dual

  4. Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. III and IV

    Energy Technology Data Exchange (ETDEWEB)

    Brieger, M. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Technische Physik

    2005-07-01

    The rigorous solution to Schroedinger's nonrelativistic time-dependent equation of a single electron's spin-orbit or magnetic hyperfine interaction reveals the full dynamics of angular momentum coupling especially in the presence of an external, arbitrarily oriented magnetic field. Besides of making a description of major dynamical properties possible in simple classical terms, it also sheds new light on the seeming quantization of states: They turn out to be exceptional states of dynamical balance, which in the field-free case are only made possible by the respective pairs of Clebsch-Gordan coefficients. Moreover, the results not only show that integer and half-integer quantum numbers of the total angular momentum only apply to this special case but that in the general case they are also able to obtain the well-known splitting pattern of the stationary energy levels in the field as produced by separately identifiable, field-dependent contributions from the spin-orbit or the magnetic hyperfine interactions on the one hand, and the magnetic dipole interaction with external magnetic fields on the other in a way not accessible to the Breit-Rabi formula. The results further demonstrate that the total magnetic moment responds quite sensitively to even weak field strengths, i.e., with substantial changes although the linear Zeeman effect suggests their seeming constancy in low fields also for levels with vertical stroke M{sub J} vertical stroke < l+1/2. Although Schroedinger's equation is equivalent to an energy representation this detailed description of the behavior of the total magnetic moment is made possible by the fortunate fact that the coupling magnetic moments enter the Hamiltonian linearly. This circumstance can be exploited to describe in full detail how the total magnetic moment behaves in an arbitrarily oriented magnetic field. It is found that its motion in this environment consists of a basic Larmor precession about the field direction

  5. ‘N-of-1-pathways’ unveils personal deregulated mechanisms from a single pair of RNA-Seq samples: towards precision medicine

    Science.gov (United States)

    Gardeux, Vincent; Achour, Ikbel; Li, Jianrong; Maienschein-Cline, Mark; Li, Haiquan; Pesce, Lorenzo; Parinandi, Gurunadh; Bahroos, Neil; Winn, Robert; Foster, Ian; Garcia, Joe G N; Lussier, Yves A

    2014-01-01

    Background The emergence of precision medicine allowed the incorporation of individual molecular data into patient care. Indeed, DNA sequencing predicts somatic mutations in individual patients. However, these genetic features overlook dynamic epigenetic and phenotypic response to therapy. Meanwhile, accurate personal transcriptome interpretation remains an unmet challenge. Further, N-of-1 (single-subject) efficacy trials are increasingly pursued, but are underpowered for molecular marker discovery. Method ‘N-of-1-pathways’ is a global framework relying on three principles: (i) the statistical universe is a single patient; (ii) significance is derived from geneset/biomodules powered by paired samples from the same patient; and (iii) similarity between genesets/biomodules assesses commonality and differences, within-study and cross-studies. Thus, patient gene-level profiles are transformed into deregulated pathways. From RNA-Seq of 55 lung adenocarcinoma patients, N-of-1-pathways predicts the deregulated pathways of each patient. Results Cross-patient N-of-1-pathways obtains comparable results with conventional genesets enrichment analysis (GSEA) and differentially expressed gene (DEG) enrichment, validated in three external evaluations. Moreover, heatmap and star plots highlight both individual and shared mechanisms ranging from molecular to organ-systems levels (eg, DNA repair, signaling, immune response). Patients were ranked based on the similarity of their deregulated mechanisms to those of an independent gold standard, generating unsupervised clusters of diametric extreme survival phenotypes (p=0.03). Conclusions The N-of-1-pathways framework provides a robust statistical and relevant biological interpretation of individual disease-free survival that is often overlooked in conventional cross-patient studies. It enables mechanism-level classifiers with smaller cohorts as well as N-of-1 studies. Software http://lussierlab.org/publications/N-of-1-pathways

  6. On the mechanism of isoprenaline- and forskolin-induced depolarization of single guinea-pig ventricular myocytes.

    Science.gov (United States)

    Egan, T M; Noble, D; Noble, S J; Powell, T; Twist, V W; Yamaoka, K

    1988-06-01

    1. Isoprenaline (10 nM to 1 microM) and forskolin (0.6-100 microM) depolarized single guinea-pig myocytes studied in vitro. Under voltage clamp both agents caused an inward current to flow. 2. These effects were abolished by propranolol (100 nM) and the beta1-antagonist metoprolol (100-200 nM), but not by the beta2-agonist [corrected] salbutamol (1 microM). 3. The interaction of isoprenaline with forskolin, caffeine or isobutylmethylxanthine (IBMX) on current amplitude was as expected if all of these drugs were causing inward current by increasing intracellular levels of cyclic adenosine monophosphate (cyclic AMP). Low concentrations of forskolin (less than 600 nM) or IBMX (less than 20 microM) potentiated the effect of isoprenaline, whereas isoprenaline caused no further inward current in cells in which high concentrations of forskolin (600 nM-100 microM) or IBMX (20 microM-1 mM) were already evoking maximum inward current. 4. Isoprenaline-induced inward current was reduced 30-50% by acetylcholine (10-30 microM). This action of acetylcholine was blocked by atropine (100 nM). 5. The effect of isoprenaline on holding current was critically dependent on temperature. The onset of the current was delayed and its amplitude reduced as the myocyte was cooled from 37 degrees C to ambient temperature (22-24 degrees C). 6. Isoprenaline-induced inward current was not affected by the potassium channel blockers barium (2 mM) or tetraethylammonium (TEA; 10-20 mM). The amplitude of the inward current did not vary as a function of [K+]o. 7. The inward current was not affected by the calcium channel blockers cadmium 1 mM, or nifedipine (10 microM), or when internal calcium was reduced by including EGTA in the recording electrode filling solution. 8. The amplitude of the current was also unaffected by caesium (5 mM), which blocks the hyperpolarization-activated, non-specific channel if, or by strophanthidin (10 microM) which blocks the Na+-K+ pump. It was unchanged by substitution

  7. Insights into the Molecular Mechanisms Underlying Mammalian P2X7 Receptor Functions and Contributions in Diseases, Revealed by Structural Modeling and Single Nucleotide Polymorphisms

    Science.gov (United States)

    Jiang, Lin-Hua; Baldwin, Jocelyn M.; Roger, Sebastien; Baldwin, Stephen A.

    2013-01-01

    The mammalian P2X7 receptors (P2X7Rs), a member of the ionotropic P2X receptor family with distinctive functional properties, play an important part in mediating extracellular ATP signaling in health and disease. A clear delineation of the molecular mechanisms underlying the key receptor properties, such as ATP-binding, ion permeation, and large pore formation of the mammalian P2X7Rs, is still lacking, but such knowledge is crucial for a better understanding of their physiological functions and contributions in diseases and for development of therapeutics. The recent breakthroughs in determining the atomic structures of the zebrafish P2X4.1R in the closed and ATP-bound open states have provided the long-awaited structural information. The human P2RX7 gene is abundant with non-synonymous single nucleotide polymorphisms (NS-SNPs), which generate a repertoire of human P2X7Rs with point mutations. Characterizations of the NS-SNPs identified in patients of various disease conditions and the resulting mutations have informed previously unknown molecular mechanisms determining the mammalian P2X7R functions and diseases. In this review, we will discuss the new insights into such mechanisms provided by structural modeling and recent functional and genetic linkage studies of NS-SNPs. PMID:23675347

  8. Insights into the molecular mechanisms underlying mammalian P2X7 receptor functions and contributions in diseases, revealed by structural modeling and single nucleotide polymorphisms

    Directory of Open Access Journals (Sweden)

    Lin-Hua eJiang

    2013-05-01

    Full Text Available The mammalian P2X7 receptors (P2X7Rs, a member of the ionotropic P2X receptor family with distinctive functional properties, play an important part in mediating extracellular ATP signaling in health and disease. A clear delineation of the molecular mechanisms underlying the key receptor properties, such as ATP-binding, ion permeation, and large pore formation of the mammalian P2X7Rs, is still lacking, but such knowledge is crucial for a better understanding of their physiological functions and contributions in diseases and for development of therapeutics. The recent breakthroughs in determining the atomic structures of the zebrafish P2X4.1R in the closed and ATP-bound open states have provided the long-awaited structural information. The human P2RX7 gene is abundant with non-synonymous single nucleotide polymorphisms (NS-SNPs, which generate a repertoire of human P2X7Rs with point mutations. Characterizations of the NS-SNPs identified in patients of various disease conditions and the resulting mutations have informed previously unknown molecular mechanisms determining the mammalian P2X7R functions and diseases. In this review, we will discuss the new insights into such mechanisms provided by structural modeling and recent functional and genetic linkage studies of NS-SNPs.

  9. Bipolar single-wall carbon nanotube field-effect transistor

    OpenAIRE

    Babic, Bakir; Iqbal, Mahdi; Schonenberger, Christian

    2002-01-01

    We use a simultaneous flow of ethylene and hydrogen gases to grow single wall carbon nanotubes by chemical vapor deposition. Strong coupling to the gate is inferred from transport measurements for both metallic and semiconducting tubes. At low-temperatures, our samples act as single-electron transistors where the transport mechanism is mainly governed by Coulomb blockade. The measurements reveal very rich quantized energy level spectra spanning from valence to conduction band. The Coulomb dia...

  10. Influence of van der Waals contact forces on the deformation mechanics of thin flexible membranes assembled from metallic or semiconducting single-wall carbon nanotubes

    Science.gov (United States)

    Hobbie, Erik K.; Harris, John; Iyer, Swathi; Huh, Ji Yeon; Fagan, Jeffrey A.; Hudson, Steven D.; Stafford, Christopher M.

    2011-03-01

    Thin membranes of single-wall carbon nanotubes (SWCNTs) assembled from either metallic or semiconducting SWCNTs are subjected to the compressive strains imposed by a stretched elastic substrate, and the mechanical characteristics of the membranes are inferred from the topography of the wrinkling instability that emerges. By depositing comparable films on quartz, we also use optical (UV-Vis-NIR) absorption spectroscopy to compute the effective London dispersion spectra of the purified materials, and from these we compute the attractive part of the van der Waals potential between nanotubes of identical electronic type as a function of separation and relative orientation. We find significant differences in the strength and shape of the contact potential depending on electronic type, which in turn are evident in the modulus and yield strain measured from the deformation of the films. Supported by the NSF through CMMI-0969155 and the DOE through DE-FG36-08GO88160.

  11. Determining fracture-mechanics characteristics of reactor pressure vessel steels applying the single-specimen compliance method and correlations to notch impact energy

    International Nuclear Information System (INIS)

    Bergmann, U.; Boehmert, J.; Viehrig, H.W.

    1995-03-01

    Fracture-mechanics crack resistance parameters based on the J integral are useful to describe the failure behaviour of high-toughness reactor pressure vessel steels. This paper presents methodical results concerning the estimation of crack growth resistance curves of precracked and sidegrooved Charpy sized 3-PB specimens by using the single specimen compliance method. Crack initiation toughness values are estimated on the basis of the measured stretch zone with and as a technical equivalent values from the crack resistant curves described by a polynom. The wide range of toughness or strength of the investigated steels allows to investigate relationships known from the literature between the upper shelf Charpy-V notch energy and the crack growth resistance behaviour. The relationships provide acceptable technical approaches, but they can only insufficiently describe the physical meaning. (orig.) [de

  12. Effects of Manganese (Ii Sulphate on Structural, Spectral, Optical, Thermal and Mechanical Properties of L-Alanine Sodium Sulphate Single Crystals

    Directory of Open Access Journals (Sweden)

    F. Praveena

    2017-04-01

    Full Text Available New Non-linear Optical materials have been attracting in the research world for their potential applications in emerging opto-electronic technology. The dipolar nature of amino acid leads to peculiar physical and chemical properties, thus making a good candidate for NLO applications. Single crystals of manganese(II sulphate doped L-Alanine sodium sulphate(LASS has been synthesized by slow evaporation technique. Structural property of the grown crystals are characterized by X-ray powder diffraction,FT-IR spectral analysis conforms all the functional groups. Thermogravity (TG and differential themogravimetric (DTA analysis have been performed to study the thermal stability of the crystals. The second harmonic generation efficiency was measured by Kurtz-Perry powder technique. The transmission and absorption of electromagnetic radiation is analysed through UV-VIS spectrum. Microhardness was measured at different applied load to understand the mechanical stability of the crystal.

  13. Microscopic mechanisms for long QT syndrome type 1 revealed by single-channel analysis of I(Ks) with S3 domain mutations in KCNQ1.

    Science.gov (United States)

    Eldstrom, Jodene; Wang, Zhuren; Werry, Daniel; Wong, Nathan; Fedida, David

    2015-02-01

    The slowly activating delayed rectifier current IKs participates in cardiac repolarization, particularly at high heart rates, and mutations in this K(+) channel complex underlie long QT syndrome (LQTS) types 1 and 5. The purpose of this study was to determine biophysical mechanisms of LQT1 through single-channel kinetic analysis of IKs carrying LQT1 mutations in the S3 transmembrane region of the pore-forming subunit KCNQ1. We analyzed cell-attached recordings from mammalian cells in which a single active KCNQ1 (wild type or mutant) and KCNE1 complex could be detected. The S3 mutants of KCNQ1 studied (D202H, I204F, V205M, and S209F), with the exception of S209F, all led to a reduction in channel activity through distinct kinetic mechanisms. D202H, I204F, and V205M showed decreased open probability (Po) compared with wild type (0.07, 0.04, and 0.12 vs 0.2); increased first latency from 1.66 to >2 seconds at +60 mV (I204F, V205M); variable-to-severe reductions in open dwell times (≥50% in V205M); stabilization of closed states (D202H); and an inability of channels to reach full conductance levels (V205M, I204F). S209F is a kinetic gain-of-function mutation with a high Po (0.40) and long open-state dwell times. S3 mutations in KCNQ1 cause diverse kinetic defects in I(Ks), affecting opening and closing properties, and can account for LQT1 phenotypes. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  14. Scanning Electron Microscopy Analysis of the Adaptation of Single-Unit Screw-Retained Computer-Aided Design/Computer-Aided Manufacture Abutments After Mechanical Cycling.

    Science.gov (United States)

    Markarian, Roberto Adrian; Galles, Deborah Pedroso; Gomes França, Fabiana Mantovani

    To measure the microgap between dental implants and custom abutments fabricated using different computer-aided design/computer-aided manufacture (CAD/CAM) methods before and after mechanical cycling. CAD software (Dental System, 3Shape) was used to design a custom abutment for a single-unit, screw-retained crown compatible with a 4.1-mm external hexagon dental implant. The resulting stereolithography file was sent for manufacturing using four CAD/CAM methods (n = 40): milling and sintering of zirconium dioxide (ZO group), cobalt-chromium (Co-Cr) sintered via selective laser melting (SLM group), fully sintered machined Co-Cr alloy (MM group), and machined and sintered agglutinated Co-Cr alloy powder (AM group). Prefabricated titanium abutments (TI group) were used as controls. Each abutment was placed on a dental implant measuring 4.1× 11 mm (SA411, SIN) inserted into an aluminum block. Measurements were taken using scanning electron microscopy (SEM) (×4,000) on four regions of the implant-abutment interface (IAI) and at a relative distance of 90 degrees from each other. The specimens were mechanically aged (1 million cycles, 2 Hz, 100 N, 37°C) and the IAI width was measured again using the same approach. Data were analyzed using two-way analysis of variance, followed by the Tukey test. After mechanical cycling, the best adaptation results were obtained from the TI (2.29 ± 1.13 μm), AM (3.58 ± 1.80 μm), and MM (1.89 ± 0.98 μm) groups. A significantly worse adaptation outcome was observed for the SLM (18.40 ± 20.78 μm) and ZO (10.42 ± 0.80 μm) groups. Mechanical cycling had a marked effect only on the AM specimens, which significantly increased the microgap at the IAI. Custom abutments fabricated using fully sintered machined Co-Cr alloy and machined and sintered agglutinated Co-Cr alloy powder demonstrated the best adaptation results at the IAI, similar to those obtained with commercial prefabricated titanium abutments after mechanical cycling. The

  15. Federal Technology Transfer Act (FTTA)

    Science.gov (United States)

    EPA's Federal Technology Transfer Act (FTTA) is a mechanism with which EPA can patent its inventions and license them to companies, through which innovative technologies can enter the marketplace to improve the environment and human health.

  16. Evolving microstructure, magnetic properties and phase transition in a mechanically alloyed Ni0.5Zn0.5Fe2O4 single sample

    Science.gov (United States)

    Ismail, Ismayadi; Hashim, Mansor; Kanagesan, Samikannu; Ibrahim, Idza Riati; Nazlan, Rodziah; Wan Ab Rahman, Wan Norailiana; Abdullah, Nor Hapishah; Mohd Idris, Fadzidah; Bahmanrokh, Ghazaleh; Shafie, Mohd Shamsul Ezzad; Manap, Masni

    2014-02-01

    We report on an investigation to unravel the dependence of magnetic properties on microstructure while they evolve in parallel under the influence of sintering temperature of a single sample of Ni0.5Zn0.5Fe2O4 synthesized via mechanical alloying. A single sample, instead of the normally practiced approach of using multiple samples, was sintered at various sintering temperatures from 500 °C to 1400 °C. The morphology of the samples was studied by means of scanning electron microscopy (SEM) equipped with EDX; density measurement was conducted using the Archimedes principle; and hysteresis measurement was carried out using a B-H hysteresisgraph system. XRD data showed that the first appearance of a single phase was at 800 °C and an amorphous phase was traced at lower sintering temperatures. We correlated the microstructure and the magnetic properties and showed that the important grain-size threshold for the appearance of significant ordered magnetism (mainly ferromagnetism) was about ≥0.3 µm. We found that there were three stages of magnetic phase evolution produced via the sintering process with increasing temperatures. The first stage was dominated by paramagnetic states with some superparamagnetic behavior; the second stage was influenced by moderately ferromagnetic states and some paramagnetic states; and the third stage consisted of strongly ferromagnetic states with negligible paramagnetic states. We found that three factors sensitively influenced the sample's content of ordered magnetism—the ferrite-phase crystallinity degree, the number of grains above the critical grain size and the number of large enough grains for domain wall accommodation.

  17. Current sharing temperature of NbTi SULTAN samples compared to prediction using a single pinning mechanism parametrization for NbTi strand

    International Nuclear Information System (INIS)

    Pong, Ian; Vostner, Alexander; Devred, Arnaud; Bessette, Denis; Mitchell, Neil; Bordini, Bernardo; Bottura, Luca; Jewell, Matthew; Long Feng; Wu Yu

    2012-01-01

    NbTi strands to be used in four of the six ITER poloidal field (PF) coils, all the correction coils (CC) and all the superconducting feeder busbars are being produced in China. Short full-size qualification conductor (cabled and jacketed) samples have been developed at ASIPP and tested at CRPP. Single pinning mechanism parametrization for this Chinese strand (type S2) has been obtained using the Bottura scaling law. The determination of the scaling parameters using a Kramer-type regression method will be described. A comparison between the critical temperature at the operating current and field of a single strand as determined by the parametrization and the current sharing temperature (T CS ) of a few conductor samples tested at the SULTAN facility will be made. The validity and limitation of the estimation will be discussed. The estimated T CS dependence on various (superconducting critical as well as geometric and volumetric) parameters will be assessed using the modelled critical surface. Errors propagated from critical current (I c ) measurements of the strands and parameter fitting, and other uncertainties, will be quantified. (paper)

  18. Microstructure and mechanical properties of a single crystal NiAl alloy with Zr or Hf rich G-phase precipitates

    Science.gov (United States)

    Locci, I. E.; Noebe, R. D.; Bowman, R. R.; Miner, R. V.; Nathal, M. V.; Darolia, R.

    1991-01-01

    The possibility of producing NiAl reinforced with the G-phase (Ni16X6Si7), where X is Zr or Hf, has been investigated. The microstructure of these NiAl alloys have been characterized in the as-cast and annealed conditions. The G-phases are present as fine cuboidal precipitates (10 to 40 nm) and have lattice parameters almost four times that of NiAl. They are coherent with the matrix and fairly resistant to coarsening during annealing heat treatments. Segregation and nonuniform precipitate distribution observed in as-cast materials were eliminated by homogenization at temperatures near 1600 K. Slow cooling from these temperatures resulted in large plate shaped precipitates, denuded zones, and a loss of coherency in some of the large particles. Faster cooling produced a homogeneous fine distribution of cuboidal G-phase particles in the matrix. Preliminary mechanical properties for the Zr-doped alloy are presented and compared to binary single crystal NiAl. The presence of these precipitates appears to have an important strengthening effect at temperatures not less than 1000 K compared to binary NiAl single crystals.

  19. Growth, optical, thermal, mechanical and dielectric studies of sodium succinate hexahydrate (β phase) single crystal: A promising third order NLO material

    Science.gov (United States)

    Mageshwari, P. S. Latha; Priya, R.; Krishnan, S.; Joseph, V.; Das, S. Jerome

    2016-11-01

    A third order nonlinear optical (NLO)single crystals of sodium succinate hexahydrate (SSH) (β phase) has been grown by a slow evaporation growth technique using aqueous solution at ambient temperature. The lattice parameters and morphology of SSH were determined by single crystal X-ray diffraction analysis. SSH crystallizes in centrosymmetric monoclinic system with space group P 21 / c and the crystalline purity was analyzed by powder X-ray diffraction analysis. The UV-vis-NIR spectrum reveals that the crystal is transparent in the entire visible region. The recorded FT-IR spectrum verified the presence of various functional groups in the material. NMR analysis of the grown crystal confirms the structural elucidation and detects the major and minor functional groups present in the title compound. ICP-OES analysis proved the presence of sodium in SSH. TG-DTA/DSCanalysis was used to investigate the thermal stability of the material. The dielectric permittivity and dielectric loss of SSH were carried out as a function of frequency for different temperatures and the results were discussed. The mechanical stability was evaluated from Vicker's microhardness test. The third order nonlinear optical properties of SSH has been investigated employing Z-scan technique with He-Ne laser operating at 632.8 nm wavelength.

  20. A vapor response mechanism study of surface-modified single-walled carbon nanotubes coated chemiresistors and quartz crystal microbalance sensor arrays.

    Science.gov (United States)

    Lu, Hung-Ling; Lu, Chia-Jung; Tian, Wei-Cheng; Sheen, Horn-Jiunn

    2015-01-01

    This paper compares the selectivity and discusses the response mechanisms of various surface-modified, single-walled carbon nanotube (SWCNT)-coated sensor arrays for the detection of volatile organic compounds (VOCs). Two types of sensor platforms, chemiresistor and quartz crystal microbalance (QCM), were used to probe the resistance changes and absorption masses during vapor sensing. Four sensing materials were used in this comparison study: pristine, acidified, esterified, and surfactant (sodium dodecyl sulfate, SDS)-coated SWCNTs. SWCNT-coated QCMs reached the response equilibrium faster than the chemiresistors did, which revealed a delay diffusion behavior at the inter-tube junction. In addition, the calibration lines for QCMs were all linear, but the chemiresistors showed curvature calibration lines which indicated less effectiveness of swelling at high concentrations. While the sorption of vapor molecules caused an increase in the resistance for most SWCNTs due to the swelling, the acidified SWCNTs showed no responses to nonpolar vapors and a negative response to hydrogen bond acceptors. This discovery provided insight into the inter-tube interlocks and conductivity modulation of acidified SWCNTs via a hydrogen bond. The results in this study provide a stepping-stone for further understanding of the mechanisms behind the vapor selectivity of surface-modified SWCNT sensor arrays. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Single fiber push-out characterization of interfacial mechanical properties in unidirectional CVI-C/SiC composites by the nano-indentation technique

    Science.gov (United States)

    Zhang, Lifeng; Ren, Chengzu; Zhou, Changling; Xu, Hongzhao; Jin, Xinmin

    2015-12-01

    The characterization of interfaces in woven ceramic matrix composites is one of the most challenging problems in composite application. In this investigation, a new model material consisting of the chemical vapor infiltration unidirectional C/SiC composites with PyC fiber coating were prepared and evaluated to predict the interfacial mechanic properties of woven composites. Single fiber push-out/push-back tests with the Berkovich indenter were conducted on the thin sliced specimens using nano-indentation technique. To give a detailed illustration of the interfacial crack propagation and failure mechanism, each sector during the push-out process was analyzed at length. The test results show that there is no detectable difference between testing a fiber in a direct vicinity to an already tested fiber and testing a fiber in vicinity to not-pushed fibers. Moreover, the interface debonding and fiber sliding mainly occur at the PyC coating, and both the fiber and surrounding matrix have no plastic deformation throughout the process. Obtained from the load-displacement curve, the interfacial debonding strength (IDS) and friction stress (IFS) amount to, respectively, 35 ± 5 MPa and 10 ± 1 MPa. Based on the findings, the interfacial properties with PyC fiber coating can be predicted. Furthermore, it is expected to provide a useful guideline for the design, evaluation and optimal application of CVI-C/SiC.

  2. Light-induced energetic decoupling as a mechanism for phycobilisome-related energy dissipation in red algae: a single molecule study.

    Directory of Open Access Journals (Sweden)

    Lu-Ning Liu

    Full Text Available BACKGROUND: Photosynthetic organisms have developed multiple protective mechanisms to prevent photodamage in vivo under high-light conditions. Cyanobacteria and red algae use phycobilisomes (PBsomes as their major light-harvesting antennae complexes. The orange carotenoid protein in some cyanobacteria has been demonstrated to play roles in the photoprotective mechanism. The PBsome-itself-related energy dissipation mechanism is still unclear. METHODOLOGY/PRINCIPAL FINDINGS: Here, single-molecule spectroscopy is applied for the first time on the PBsomes of red alga Porphyridium cruentum, to detect the fluorescence emissions of phycoerythrins (PE and PBsome core complex simultaneously, and the real-time detection could greatly characterize the fluorescence dynamics of individual PBsomes in response to intense light. CONCLUSIONS/SIGNIFICANCE: Our data revealed that strong green-light can induce the fluorescence decrease of PBsome, as well as the fluorescence increase of PE at the first stage of photobleaching. It strongly indicated an energetic decoupling occurring between PE and its neighbor. The fluorescence of PE was subsequently observed to be decreased, showing that PE was photobleached when energy transfer in the PBsomes was disrupted. In contrast, the energetic decoupling was not observed in either the PBsomes fixed with glutaraldehyde, or the mutant PBsomes lacking B-PE and remaining b-PE. It was concluded that the energetic decoupling of the PBsomes occurs at the specific association between B-PE and b-PE within the PBsome rod. Assuming that the same process occurs also at the much lower physiological light intensities, such a decoupling process is proposed to be a strategy corresponding to PBsomes to prevent photodamage of the photosynthetic reaction centers. Finally, a novel photoprotective role of gamma-subunit-containing PE in red algae was discussed.

  3. Development of a Mechanism for Measuring Forces and Aligning Moment Acting on the Steering Wheels of a Four-Wheel Vehicle

    Directory of Open Access Journals (Sweden)

    A Hajiahmad

    2014-09-01

    Full Text Available In this paper, a low-cost dynamometer for rolling, steered wheels is described. The dynamometer was constructed to determine whether such an instrumented mechanism was practical. Four S-beam load cells, an Opto-counter and a potentiometer were used to obtain all moments, and forces using dynamic and kinematic analysis. Minimal simplifying assumptions considered for the required calculations. Overturning, aligning and rolling resistance moments besides vertical force are directly measured by the load cells. The Opto-counter detects wheel angular velocity and the potentiometer was used to measure the steering angle. The results showed that the mechanism was very well calibrated with a coefficient of determination of over 0.99 and can be used to define wheel dynamic behavior.

  4. Mechanisms of Cisplatin-Induced Apoptosis and of Cisplatin Sensitivity: Potential of BIN1 to Act as a Potent Predictor of Cisplatin Sensitivity in Gastric Cancer Treatment

    OpenAIRE

    Tanida, Satoshi; Mizoshita, Tsutomu; Ozeki, Keiji; Tsukamoto, Hironobu; Kamiya, Takeshi; Kataoka, Hiromi; Sakamuro, Daitoku; Joh, Takashi

    2012-01-01

    Cisplatin is the most important and efficacious chemotherapeutic agent for the treatment of advanced gastric cancer. Cisplatin forms inter- and intrastrand crosslinked DNA adducts and its cytotoxicity is mediated by propagation of DNA damage recognition signals to downstream pathways involving ATR, p53, p73, and mitogen-activated protein kinases, ultimately resulting in apoptosis. Cisplatin resistance arises through a multifactorial mechanism involving reduced drug uptake, increased drug inac...

  5. An examination of resveratrol's mechanisms of action in human tissue: impact of a single dose in vivo and dose responses in skeletal muscle ex vivo.

    Directory of Open Access Journals (Sweden)

    Cameron B Williams

    Full Text Available The current study tested the hypothesis that a single, moderate dose of RSV would activate the AMPK/SIRT1 axis in human skeletal muscle and adipose tissue. Additionally, the effects of RSV on mitochondrial respiration in PmFBs were examined. Eight sedentary men (23.8±2.4 yrs; BMI: 32.7±7.1 reported to the lab on two occasions where they were provided a meal supplemented with 300 mg of RSV or a placebo. Blood samples, and a muscle biopsy were obtained in the fasted state and again, with the addition of an adipose tissue biopsy, two hours post-prandial. The effect of RSV on mitochondrial respiration was examined in PmFBs taken from muscle biopsies from an additional eight men (23.4±5.4 yrs; BMI: 24.4±2.8. No effect of RSV was observed on nuclear SIRT1 activity, acetylation of p53, or phosphorylation of AMPK, ACC or PKA in either skeletal muscle or adipose tissue. A decrease in post absorptive insulin levels was accompanied by elevated skeletal muscle phosphorylation of p38 MAPK, but no change in either skeletal muscle or adipose tissue insulin signalling. Mitochondrial respiration in PmFBs was rapidly inhibited by RSV at 100-300 uM depending on the substrate examined. These results question the efficacy of a single dose of RSV at altering skeletal muscle and adipose tissue AMPK/SIRT1 activity in humans and suggest that RSV mechanisms of action in humans may be associated with altered cellular energetics resulting from impaired mitochondrial ATP production.

  6. Predominant Occupation of the Class I MHC Molecule H-2Kwm7 with a Single Self-peptide Suggests a Mechanism for its Diabetes-protective Effect

    Energy Technology Data Exchange (ETDEWEB)

    Brims, D.; Qian, J; Jarchum, I; Mikesh, L; Palmieri, E; Ramagopal, U; Malashkevich, V; Chaparro, R; Lund, T; et. al.

    2010-01-01

    Type 1 diabetes (T1D) is an autoimmune disease characterized by T cell-mediated destruction of insulin-producing pancreatic {beta} cells. In both humans and the non-obese diabetic (NOD) mouse model of T1D, class II MHC alleles are the primary determinant of disease susceptibility. However, class I MHC genes also influence risk. These findings are consistent with the requirement for both CD{sup 4+} and CD{sup 8+} T cells in the pathogenesis of T1D. Although a large body of work has permitted the identification of multiple mechanisms to explain the diabetes-protective effect of particular class II MHC alleles, studies examining the protective influence of class I alleles are lacking. Here, we explored this question by performing biochemical and structural analyses of the murine class I MHC molecule H-2K{sup wm7}, which exerts a diabetes-protective effect in NOD mice. We have found that H-2K{sup wm7} molecules are predominantly occupied by the single self-peptide VNDIFERI, derived from the ubiquitous protein histone H2B. This unexpected finding suggests that the inability of H-2K{sup wm7} to support T1D development could be due, at least in part, to the failure of peptides from critical {beta}-cell antigens to adequately compete for binding and be presented to T cells. Predominant presentation of a single peptide would also be expected to influence T-cell selection, potentially leading to a reduced ability to select a diabetogenic CD{sup 8+} T-cell repertoire. The report that one of the predominant peptides bound by T1D-protective HLA-A*31 is histone derived suggests the potential translation of our findings to human diabetes-protective class I MHC molecules.

  7. Bulk crystal growth, optical, mechanical and ferroelectric properties of new semiorganic nonlinear optical and piezoelectric Lithium nitrate monohydrate oxalate single crystal

    Science.gov (United States)

    Dalal, Jyoti; Kumar, Binay

    2016-01-01

    New semiorganic nonlinear optical single crystals of Lithium nitrate oxalate monohydrate (LNO) were grown by slow evaporation solution technique. Single crystal X-ray diffraction study indicated that LNO crystal belongs to the triclinic system with space group P1. Various functional groups present in the material were identified by FTIR and Raman analysis. UV-vis study showed the high transparency of crystals with a wide band gap 5.01 eV. Various Optical constants i.e. Urbach energy (Eu), extinction coefficient (K), refractive index, optical conductivity, electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data which have applications in optoelectronic devices. A sharp emission peak was found at 438 nm in photoluminescence measurement, which revealed suitability of crystal for fabricating violet lasers. In dielectric studies, a peak has been observed at 33 °C which is due to ferroelectric to paraelectric phase transition. Piezoelectric charge coefficients (d33 = 9.2 pC/N and g33) have been calculated, which make it a suitable for piezoelectric devices applications. In ferroelectric studies, a saturated loop was found in which the values of coercive field and remnant polarization were found to be 2.18 kV/cm and 0.39 μC/cm2, respectively. Thermal behavior was studied by TGA and DSC studies. The relative SHG efficiency of LNO was found to be 1.2 times that of KDP crystal. In microhardness study, Meyer's index value was found to be 1.78 which revealed its soft nature. These optical, dielectric, piezoelectric, ferroelectric, mechanical and non-linear optical properties of grown crystal establish the usefulness of this material for optoelectronics, non-volatile memory and piezoelectric devices applications.

  8. Online differentiation of mineral phase in aerosol particles by ion formation mechanism using a LAAP-TOF single-particle mass spectrometer

    Directory of Open Access Journals (Sweden)

    N. A. Marsden

    2018-01-01

    Full Text Available Mineralogy of silicate mineral dust has a strong influence on climate and ecosystems due to variation in physiochemical properties that result from differences in composition and crystal structure (mineral phase. Traditional offline methods of analysing mineral phase are labour intensive and the temporal resolution of the data is much longer than many atmospheric processes. Single-particle mass spectrometry (SPMS is an established technique for the online size-resolved measurement of particle composition by laser desorption ionisation (LDI followed by time-of-flight mass spectrometry (TOF-MS. Although non-quantitative, the technique is able to identify the presence of silicate minerals in airborne dust particles from markers of alkali metals and silicate molecular ions in the mass spectra. However, the differentiation of mineral phase in silicate particles by traditional mass spectral peak area measurements is not possible. This is because instrument function and matrix effects in the ionisation process result in variations in instrument response that are greater than the differences in composition between common mineral phases.In this study, we introduce a novel technique that enables the differentiation of mineral phase in silicate mineral particles by ion formation mechanism measured from subtle changes in ion arrival times at the TOF-MS detector. Using a combination of peak area and peak centroid measurements, we show that the arrangement of the interstitial alkali metals in the crystal structure, an important property in silicate mineralogy, influences the ion arrival times of elemental and molecular ion species in the negative ion mass spectra. A classification scheme is presented that allowed for the differentiation of illite–smectite, kaolinite and feldspar minerals on a single-particle basis. Online analysis of mineral dust aerosol generated from clay mineral standards produced mineral fractions that are in agreement with bulk

  9. Online differentiation of mineral phase in aerosol particles by ion formation mechanism using a LAAP-TOF single-particle mass spectrometer

    Science.gov (United States)

    Marsden, Nicholas A.; Flynn, Michael J.; Allan, James D.; Coe, Hugh

    2018-01-01

    Mineralogy of silicate mineral dust has a strong influence on climate and ecosystems due to variation in physiochemical properties that result from differences in composition and crystal structure (mineral phase). Traditional offline methods of analysing mineral phase are labour intensive and the temporal resolution of the data is much longer than many atmospheric processes. Single-particle mass spectrometry (SPMS) is an established technique for the online size-resolved measurement of particle composition by laser desorption ionisation (LDI) followed by time-of-flight mass spectrometry (TOF-MS). Although non-quantitative, the technique is able to identify the presence of silicate minerals in airborne dust particles from markers of alkali metals and silicate molecular ions in the mass spectra. However, the differentiation of mineral phase in silicate particles by traditional mass spectral peak area measurements is not possible. This is because instrument function and matrix effects in the ionisation process result in variations in instrument response that are greater than the differences in composition between common mineral phases.In this study, we introduce a novel technique that enables the differentiation of mineral phase in silicate mineral particles by ion formation mechanism measured from subtle changes in ion arrival times at the TOF-MS detector. Using a combination of peak area and peak centroid measurements, we show that the arrangement of the interstitial alkali metals in the crystal structure, an important property in silicate mineralogy, influences the ion arrival times of elemental and molecular ion species in the negative ion mass spectra. A classification scheme is presented that allowed for the differentiation of illite-smectite, kaolinite and feldspar minerals on a single-particle basis. Online analysis of mineral dust aerosol generated from clay mineral standards produced mineral fractions that are in agreement with bulk measurements reported by

  10. Mechanism-based pharmacokinetic/pharmacodynamic modeling of rat prefrontal cortical dopamine response to dual acting norepinephrine reuptake inhibitor and 5-HT1A partial agonist.

    Science.gov (United States)

    Li, Cheryl Shuang-wu; Zhang, Liming; Haske, Taraneh; Dounay, Amy; Gray, David; Barta, Nancy; Brodfuehrer, Joanne; Lepsy, Christopher; Campbell, Brian

    2012-06-01

    Evidence suggests that compounds possessing both norepinephrine reuptake inhibition and 5-HT(1A) partial agonism (NRI/5-HT(1A)) activities may have a greater efficacy in treating neuropsychiatric disorders than compounds possessing either activity alone. The objectives of the present study were first to characterize the pharmacokinetic/pharmacodynamic (PK/PD) relationship of the plasma concentrations of atomoxetine (NRI) and buspirone (5-HT(1A) partial agonist), administered alone and in combination, on the prefrontal cortex dopamine levels in rats, and second to use the model developed to characterize the PK/PD relationship of novel NRI/5-HT(1A) compounds, PF-04269339 and PF-03529936, in a NRI/5-HT(1A) drug discovery program. Maximal dopamine elevation was twofold higher after administration of atomoxetine and buspirone in combination, PF-04269339, or PF-03529936 than after administration of atomoxetine or buspirone alone. A mechanism-based extended indirect response model characterized the time profiles of the prefrontal cortex dopamine response to atomoxetine and buspirone, administered alone or in combination. After fixing three mechanism-specific pharmacodynamic parameters (I (max) and γ2 for NRI and γ1 for 5-HT(1A)) based on the model for atomoxetine and/or buspirone, the model fitted the exposure-response profiles of PF-04269339 and PF-03529936 well. Good in vitro-to-in vivo correlation was demonstrated with the compound-specific pharmacodynamic parameters (IC(50) for NRI and SC(50) and S (max) for 5-HT(1A)) across the compounds. In summary, a piecewise modeling approach was used successfully for the characterization of the PK/PD relationship of novel NRI/5-HT(1A) compounds on prefrontal cortex dopamine levels in rats. The application and value of the mechanism-based modeling in the dual pharmacology drug discovery program are also discussed.

  11. UVB induces a genome-wide acting negative regulatory mechanism that operates at the level of transcription initiation in human cells.

    Science.gov (United States)

    Gyenis, Akos; Umlauf, David; Ujfaludi, Zsuzsanna; Boros, Imre; Ye, Tao; Tora, Làszlò

    2014-07-01

    Faithful transcription of DNA is constantly threatened by different endogenous and environmental genotoxic effects. Transcription coupled repair (TCR) has been described to stop transcription and quickly remove DNA lesions from the transcribed strand of active genes, permitting rapid resumption of blocked transcription. This repair mechanism has been well characterized in the past using individual target genes. Moreover, numerous efforts investigated the fate of blocked RNA polymerase II (Pol II) during DNA repair mechanisms and suggested that stopped Pol II complexes can either backtrack, be removed and degraded or bypass the lesions to allow TCR. We investigated the effect of a non-lethal dose of UVB on global DNA-bound Pol II distribution in human cells. We found that the used UVB dose did not induce Pol II degradation however surprisingly at about 93% of the promoters of all expressed genes Pol II occupancy was seriously reduced 2-4 hours following UVB irradiation. The presence of Pol II at these cleared promoters was restored 5-6 hours after irradiation, indicating that the negative regulation is very dynamic. We also identified a small set of genes (including several p53 regulated genes), where the UVB-induced Pol II clearing did not operate. Interestingly, at promoters, where Pol II promoter clearance occurs, TFIIH, but not TBP, follows the behavior of Pol II, suggesting that at these genes upon UVB treatment TFIIH is sequestered for DNA repair by the TCR machinery. In agreement, in cells where the TCR factor, the Cockayne Syndrome B protein, was depleted UVB did not induce Pol II and TFIIH clearance at promoters. Thus, our study reveals a UVB induced negative regulatory mechanism that targets Pol II transcription initiation on the large majority of transcribed gene promoters, and a small subset of genes, where Pol II escapes this negative regulation.

  12. UVB induces a genome-wide acting negative regulatory mechanism that operates at the level of transcription initiation in human cells.

    Directory of Open Access Journals (Sweden)

    Akos Gyenis

    2014-07-01

    Full Text Available Faithful transcription of DNA is constantly threatened by different endogenous and environmental genotoxic effects. Transcription coupled repair (TCR has been described to stop transcription and quickly remove DNA lesions from the transcribed strand of active genes, permitting rapid resumption of blocked transcription. This repair mechanism has been well characterized in the past using individual target genes. Moreover, numerous efforts investigated the fate of blocked RNA polymerase II (Pol II during DNA repair mechanisms and suggested that stopped Pol II complexes can either backtrack, be removed and degraded or bypass the lesions to allow TCR. We investigated the effect of a non-lethal dose of UVB on global DNA-bound Pol II distribution in human cells. We found that the used UVB dose did not induce Pol II degradation however surprisingly at about 93% of the promoters of all expressed genes Pol II occupancy was seriously reduced 2-4 hours following UVB irradiation. The presence of Pol II at these cleared promoters was restored 5-6 hours after irradiation, indicating that the negative regulation is very dynamic. We also identified a small set of genes (including several p53 regulated genes, where the UVB-induced Pol II clearing did not operate. Interestingly, at promoters, where Pol II promoter clearance occurs, TFIIH, but not TBP, follows the behavior of Pol II, suggesting that at these genes upon UVB treatment TFIIH is sequestered for DNA repair by the TCR machinery. In agreement, in cells where the TCR factor, the Cockayne Syndrome B protein, was depleted UVB did not induce Pol II and TFIIH clearance at promoters. Thus, our study reveals a UVB induced negative regulatory mechanism that targets Pol II transcription initiation on the large majority of transcribed gene promoters, and a small subset of genes, where Pol II escapes this negative regulation.

  13. An Explicit Formulation of Singularity-Free Dynamic Equations of Mechanical Systems in Lagrangian Form---Part one: Single Rigid Bodies

    Directory of Open Access Journals (Sweden)

    Pål Johan From

    2012-04-01

    Full Text Available This paper presents the explicit dynamic equations of a mechanical system. The equations are presented so that they can easily be implemented in a simulation software or controller environment and are also well suited for system and controller analysis. The dynamics of a general mechanical system consisting of one or more rigid bodies can be derived from the Lagrangian. We can then use several well known properties of Lie groups to guarantee that these equations are well defined. This will, however, often lead to rather abstract formulation of the dynamic equations that cannot be implemented in a simulation software directly. In this paper we close this gap and show what the explicit dynamic equations look like. These equations can then be implemented directly in a simulation software and no background knowledge on Lie theory and differential geometry on the practitioner's side is required. This is the first of two papers on this topic. In this paper we derive the dynamics for single rigid bodies, while in the second part we study multibody systems. In addition to making the equations more accessible to practitioners, a motivation behind the papers is to correct a few errors commonly found in literature. For the first time, we show the detailed derivations and how to arrive at the correct set of equations. We also show through some simple examples that these correspond with the classical formulations found from Lagrange's equations. The dynamics is derived from the Boltzmann--Hamel equations of motion in terms of local position and velocity variables and the mapping to the corresponding quasi-velocities. Finally we present a new theorem which states that the Boltzmann--Hamel formulation of the dynamics is valid for all transformations with a Lie group topology. This has previously only been indicated through examples, but here we also present the formal proof. The main motivation of these papers is to allow practitioners not familiar with

  14. Differences in the mechanical properties of the developing cerebral cortical proliferative zone between mice and ferrets at both the tissue and single-cell levels

    Directory of Open Access Journals (Sweden)

    Arata Nagasaka

    2016-11-01

    Full Text Available Cell-producing events in developing tissues are mechanically dynamic throughout the cell cycle. In many epithelial systems, cells are apicobasally tall, with nuclei and somata that adopt different apicobasal positions because nuclei and somata move in a cell cycle–dependent manner. This movement is apical during G2 phase and basal during G1 phase, whereas mitosis occurs at the apical surface. These movements are collectively referred to as interkinetic nuclear migration, and such epithelia are called pseudostratified. The embryonic mammalian cerebral cortical neuroepithelium is a good model for highly pseudostratified epithelia, and we previously found differences between mice and ferrets in both horizontal cellular density (greater in ferrets and nuclear/somal movements (slower during G2 and faster during G1 in ferrets. These differences suggest that neuroepithelial cells alter their nucleokinetic behavior in response to physical factors that they encounter, which may form the basis for evolutionary transitions towards more abundant brain-cell production from mice to ferrets and primates. To address how mouse and ferret neuroepithelia may differ physically in a quantitative manner, we used atomic force microscopy to determine that the vertical stiffness of their apical surface is greater in ferrets (Young’s modulus = 1700 Pa than in mice (1400 Pa. We systematically analyzed factors underlying the apical-surface stiffness through experiments to pharmacologically inhibit actomyosin or microtubules and to examine recoiling behaviors of the apical surface upon laser ablation and also through electron microscopy to observe adherens junction. We found that although both actomyosin and microtubules are partly responsible for the apical-surface stiffness, the mousesingle, dissociated neuroepithelial cells is

  15. Sclerostin is a locally acting regulator of late-osteoblast/preosteocyte differentiation and regulates mineralization through a MEPE-ASARM-dependent mechanism.

    Science.gov (United States)

    Atkins, Gerald J; Rowe, Peter S; Lim, Hui P; Welldon, Katie J; Ormsby, Renee; Wijenayaka, Asiri R; Zelenchuk, Lesya; Evdokiou, Andreas; Findlay, David M

    2011-07-01

    The identity of the cell type responsive to sclerostin, a negative regulator of bone mass, is unknown. Since sclerostin is expressed in vivo by mineral-embedded osteocytes, we tested the hypothesis that sclerostin would regulate the behavior of cells actively involved in mineralization in adult bone, the preosteocyte. Differentiating cultures of human primary osteoblasts exposed to recombinant human sclerostin (rhSCL) for 35 days displayed dose- and time-dependent inhibition of in vitro mineralization, with late cultures being most responsive in terms of mineralization and gene expression. Treatment of advanced (day 35) cultures with rhSCL markedly increased the expression of the preosteocyte marker E11 and decreased the expression of mature markers DMP1 and SOST. Concomitantly, matrix extracellular phosphoglycoprotein (MEPE) expression was increased by rhSCL at both the mRNA and protein levels, whereas PHEX was decreased, implying regulation through the MEPE-ASARM axis. We confirmed that mineralization by human osteoblasts is exquisitely sensitive to the triphosphorylated ASARM-PO4 peptide. Immunostaining revealed that rhSCL increased the endogenous levels of MEPE-ASARM. Importantly, antibody-mediated neutralization of endogenous MEPE-ASARM antagonized the effect of rhSCL on mineralization, as did the PHEX synthetic peptide SPR4. Finally, we found elevated Sost mRNA expression in the long bones of HYP mice, suggesting that sclerostin may drive the increased MEPE-ASARM levels and mineralization defect in this genotype. Our results suggest that sclerostin acts through regulation of the PHEX/MEPE axis at the preosteocyte stage and serves as a master regulator of physiologic bone mineralization, consistent with its localization in vivo and its established role in the inhibition of bone formation. Copyright © 2011 American Society for Bone and Mineral Research.

  16. CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

    Science.gov (United States)

    Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter N.; Austin, Phillip H.; Bacmeister, Julio T.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; DelGenio, Anthony; hide

    2013-01-01

    1] CGILS-the CFMIP-GASS Intercomparison of Large Eddy Models (LESs) and single column models (SCMs)-investigates the mechanisms of cloud feedback in SCMs and LESs under idealized climate change perturbation. This paper describes the CGILS results from 15 SCMs and 8 LES models. Three cloud regimes over the subtropical oceans are studied: shallow cumulus, cumulus under stratocumulus, and well-mixed coastal stratus/stratocumulus. In the stratocumulus and coastal stratus regimes, SCMs without activated shallow convection generally simulated negative cloud feedbacks, while models with active shallow convection generally simulated positive cloud feedbacks. In the shallow cumulus alone regime, this relationship is less clear, likely due to the changes in cloud depth, lateral mixing, and precipitation or a combination of them. The majority of LES models simulated negative cloud feedback in the well-mixed coastal stratus/stratocumulus regime, and positive feedback in the shallow cumulus and stratocumulus regime. A general framework is provided to interpret SCM results: in a warmer climate, the moistening rate of the cloudy layer associated with the surface-based turbulence parameterization is enhanced; together with weaker large-scale subsidence, it causes negative cloud feedback. In contrast, in the warmer climate, the drying rate associated with the shallow convection scheme is enhanced. This causes positive cloud feedback. These mechanisms are summarized as the "NESTS" negative cloud feedback and the "SCOPE" positive cloud feedback (Negative feedback from Surface Turbulence under weaker Subsidence-Shallow Convection PositivE feedback) with the net cloud feedback depending on how the two opposing effects counteract each other. The LES results are consistent with these interpretations

  17. S. 1225: to bill to amend the Atomic Energy Act of 1954, as amended, to establish a comprehensive, equitable, reliable, and efficient mechanism for full compensation of the public in the event of an accident. Introduced in the Senate of the United States, Ninety-Ninth Congress, Second Session, May 24, 1985

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    The Price-Anderson Act Amendments of 1985 amend the Atomic Energy Act of 1954 to establish a comprehensive, equitable, reliable, and efficient mechanism for full compensation of the public in the event of an accident. The amended Act sets the amount of financial protection required as the amount of liability insurance available from private sources, with power plants having a rated capacity of 100,000 KWe or more required to have the maximum amount available at reasonable cost. The Act also changes the terms of indemnification agreements for activities done under contract to DOE

  18. Post-injection delirium/sedation syndrome in patients with schizophrenia treated with olanzapine long-acting injection, II: investigations of mechanism

    Directory of Open Access Journals (Sweden)

    Stickelmeyer Mary

    2010-06-01

    Full Text Available Abstract Background Olanzapine long-acting injection (LAI is a salt-based depot antipsychotic combining olanzapine and pamoic acid. The slow intramuscular dissolution of this practically insoluble salt produces an extended release of olanzapine lasting up to 4 weeks. However, in a small number of injections ( Methods Healthcare providers involved in the PDSS cases were queried for clinical information around the events. Plasma samples from patients experiencing PDSS were collected when possible (12/30 cases and olanzapine concentrations compared with the known pharmacokinetic profile for olanzapine LAI. Product batches and used vials from the PDSS cases were evaluated for compliance with established manufacturing standards and/or possible user error. Because this depot formulation depends upon slow dissolution at the intramuscular injection site, in-vitro experiments were conducted to assess solubility of olanzapine pamoate in various media. Results Injection administrators reported no unusual occurrences during the injection. No anomalies were found with the product batches or the remaining suspension in the used vials. Olanzapine concentrations during PDSS events were higher than the expected 5-73 ng/mL range, with concentrations exceeding 100 ng/mL and in some cases reaching >600 ng/mL during the first hours after injection but then returning to the expected therapeutic range within 24 to 72 hours. Solubility and dissolution rate of olanzapine pamoate were also found to be substantially greater in plasma than in other media such as those approximating the environment in muscle tissue. Conclusions Manufacturing irregularities, improper drug reconstitution, and inappropriate dosing were ruled out as possible causes of PDSS. In-vitro solubility and in-vivo pharmacokinetic investigations suggest that PDSS is related to exposure of the injected product to a substantial volume of blood. This exposure is most likely the result of unintended partial

  19. Hemodynamic mechanisms of the attenuated blood pressure response to mental stress after a single bout of maximal dynamic exercise in healthy subjects

    Directory of Open Access Journals (Sweden)

    F.J. Neves

    2012-07-01

    Full Text Available To determine the hemodynamic mechanisms responsible for the attenuated blood pressure response to mental stress after exercise, 26 healthy sedentary individuals (age 29 ± 8 years underwent the Stroop color-word test before and 60 min after a bout of maximal dynamic exercise on a treadmill. A subgroup (N = 11 underwent a time-control experiment without exercise. Blood pressure was continuously and noninvasively recorded by infrared finger photoplethysmography. Stroke volume was derived from pressure signals, and cardiac output and peripheral vascular resistance were calculated. Perceived mental stress scores were comparable between mental stress tests both in the exercise (P = 0.96 and control (P = 0.24 experiments. After exercise, the blood pressure response to mental stress was attenuated (pre: 10 ± 13 vs post: 6 ± 7 mmHg; P 0.05. In conclusion, a single bout of maximal dynamic exercise attenuates the blood pressure response to mental stress in healthy subjects, along with lower stroke volume and cardiac output, denoting an acute modulatory action of exercise on the central hemodynamic response to mental stress.

  20. The mechanism of the transient depression of the erythropoietic rate induced in the rat by a single injection of uranyl nitrate

    International Nuclear Information System (INIS)

    Giglio, M.J.; Brandan, N.; Leal, T.L.; Bozzini, C.E.

    1989-01-01

    With the purpose of assessing the effect of uranyl nitrate (UN) on the rate of erythropoiesis, 1 mg/kg of the compound was injected iv to adult female Wistar rats. The dosing vehicle was injected into control animals. A single injection of UN induced a transient depression of the rate of red cell volume 59 Fe uptake, which reached its lowest value (68% depression) by the seventh postinjection day. By 14 days, 59 Fe incorporation had returned to normal. The amount of iron going to erythroid tissue per hour, reticulocyte count, and immunoreactive erythropoietin concentration in both plasma and kidney extracts were also significantly depressed in UN-treated rats in relation to these values in vehicle-injected rats by the seventh postinjection day. Dose-response curves for exogenous erythropoietin (Epo) performed in polycythemic intact and UN-treated rats 7 days after drug injection revealed a significant depression of the response in UN-injected animals. Moreover, bone marrow cells obtained from rats pretreated with UN formed a reduced number of erythroid colonies in vitro in response to Epo. Therefore, possible mechanisms for the observed transient depression in the rate of erythropoiesis associated with acute UN treatment include decreased Epo production and direct or indirect damage of erythroid progenitor cells

  1. Opto-mechanical design of a buckling cavity in a novel high-performance outside-plant robust field installable single-mode fibre connector

    Science.gov (United States)

    Ebraert, Evert; Van Erps, Jürgen; Beri, Stefano; Watté, Jan; Thienpont, Hugo

    2014-05-01

    Fibre-to-the-home (FTTH) networks provide an ideal means to reach the goal the European Union has set to provide 50 % of the households with a broadband connection faster than 100 Mb/s. Deployment of FTTH networks, which is still costly today, could be significantly boosted by novel ferrule-less connectors which don't require highly skilled personnel and allow installation in the field. We propose a ferrule-less connector in which two single-mode fibres (SMFs) are aligned and maintain physical contact by ensuring that at least one fibre is in a buckled state. To this end, we design a cavity in which a fibre can buckle in a controlled way. Using finite element analysis simulations to investigate the shape of the formed buckle for various buckling cavity lengths, we show that it can be accurately approximated by a cosine function. In addition, the optical performance of a buckled SMF is investigated by bending loss calculations and simulations. We show a good agreement between the analytical and the simulated bending loss results for a G.652 fibre at a wavelength of 1550 nm. Buckling cavity lengths smaller than 20 mm should be avoided to keep the optical bending loss due to buckling below 0.1 dB. In this case the cavity height should at least be 2 mm to avoid mechanical confinement of the fibre.

  2. Granulomatous Lung Disease Requiring Mechanical Ventilation Induced by a Single Application of Oxaliplatin-Based Chemotherapy for Colorectal Cancer: A Case Report

    Directory of Open Access Journals (Sweden)

    Dane Wildner

    2013-01-01

    Full Text Available Combined chemotherapeutic regimens in conjunction with oxaliplatin are considered safe and effective treatment options in the clinical management of metastatic colorectal cancer. A 62-year-old male patient with a metastatic rectal carcinoma developed a pulmonary reaction after the first application of the combined standard chemotherapy regimen (5-fluorouracil and sodium folinic acid as a 24 h infusion and oxaliplatin. Following the first dose of chemotherapy, the patient developed acute dyspnoea and fever. A computerised scan of the chest revealed bilateral pulmonary patchy consolidation. Despite high-dose empiric antibiotic and antimycotic treatment, no clinical improvement was seen. The patient's condition deteriorated, and he required invasive mechanical ventilation. Diagnostic thoracoscopic wedge resections were performed for further diagnosis. The histological workup revealed distinct granulomatous inflammation, but no microbial pathogens were to be found. Thereupon, a drug-induced reaction to chemotherapy was suspected and high-dose steroid treatment initiated. Subsequently, the patient's respiratory condition improved and he was extubated. The present case exemplifies the rare course of a bilateral pneumonia-like, drug-induced granulomatous reaction following a single application of oxaliplatin. In addition to the known side effects of oxaliplatin-containing combination chemotherapy, unexpected serious adverse events in the form of pulmonary toxicities should also be taken into account.

  3. Effect of rare-earth dopants on the growth and structural, optical, electrical and mechanical properties of L-arginine phosphate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Arjunan, S., E-mail: arjunan_hce@yahoo.co.i [Department of Physics, Sri Ramachandra University, Porur, Chennai (India); Bhaskaran, A. [Department of Physics, Dr. Ambedkar Government College, Chennai (India); Kumar, R. Mohan; Mohan, R. [Department of Physics, Presidency College, Chennai (India); Jayavel, R. [Crystal Growth Centre, Anna University, Chennai (India)

    2010-09-17

    Research highlights: {yields} Thorium, Lanthanum and Cerium rare-earth ions were doped with L-arginine phosphate material and the crystals were grown by slow evaporation technique. {yields} The transparency of the rare-earth doped LAP crystals has enhanced compared to pure LAP. {yields} The powder SHG measurements revealed that the SHG output of rare-earth doped LAP crystals increases considerably compared to that of LAP. {yields} Vicker's hardness number of as-grown crystal of LAP is higher than that of rare-earth doped LAP crystals. - Abstract: Effect of Thorium, Lanthanum and Cerium rare-earth ions on the growth and properties of L-arginine phosphate single crystals has been reported. The incorporation of rare-earth dopants into the L-arginine phosphate crystals is confirmed by Inductively Coupled Plasma-Mass Spectroscopy analysis. The unit cell parameters for pure and rare-earth doped L-arginine phosphate crystals have been estimated by powder X-ray diffraction studies. UV-visible studies revealed the transmittance percentage and cut-off wavelengths of the grown crystals. Powder second harmonic generation measurement has been carried out for pure and doped L-arginine phosphate crystals. The dielectric behavior of the grown crystals was analyzed for different frequencies at room temperature. The mechanical properties have been determined for pure and the doped L-arginine phosphate crystals.

  4. Capillary electrophoretic enantioseparation of basic drugs using a new single-isomer cyclodextrin derivative and theoretical study of the chiral recognition mechanism.

    Science.gov (United States)

    Liu, Yongjing; Deng, Miaoduo; Yu, Jia; Jiang, Zhen; Guo, Xingjie

    2016-05-01

    A novel single-isomer cyclodextrin derivative, heptakis {2,6-di-O-[3-(1,3-dicarboxyl propylamino)-2-hydroxypropyl]}-β-cyclodextrin (glutamic acid-β-cyclodextrin) was synthesized and used as a chiral selector in capillary electrophoresis for the enantioseparation of 12 basic drugs, including terbutaline, clorprenaline, tulobuterol, clenbuterol, procaterol, carvedilol, econazole, miconazole, homatropine methyl bromide, brompheniramine, chlorpheniramine and pheniramine. The primary factors affecting separation efficiency, which include the background electrolyte pH, the concentration of glutamic acid-β-cyclodextrin and phosphate buffer concentration, were investigated. Satisfactory enantioseparations were obtained using an uncoated fused-silica capillary of 50 cm (effective length 40 cm) × 50 μm id with 120 mM phosphate buffer (pH 2.5-4.0) containing 0.5-4.5 mM glutamic acid-β-cyclodextrin as background electrolyte. A voltage of 20 kV was applied and the capillary temperature was kept at 20°C. The results proved that glutamic acid-β-cyclodextrin was an effective chiral selector for studied 12 basic drugs. Moreover, the possible chiral recognition mechanism of brompheniramine, chlorpheniramine and pheniramine on glutamic acid-β-cyclodextrin was investigated using the semi-empirical Parametric Method 3. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. IGFBP2 Produces Rapid-Acting and Long-Lasting Effects in Rat Models of Posttraumatic Stress Disorder via a Novel Mechanism Associated with Structural Plasticity.

    Science.gov (United States)

    Burgdorf, Jeffrey; Colechio, Elizabeth M; Ghoreishi-Haack, Nayereh; Gross, Amanda L; Rex, Christopher S; Zhang, Xiao-Lei; Stanton, Patric K; Kroes, Roger A; Moskal, Joseph R

    2017-06-01

    Posttraumatic stress disorder is an anxiety disorder characterized by deficits in the extinction of aversive memories. Insulin-like growth factor 1 (IGF1) is the only growth factor that has shown anxiolytic and antidepressant properties in human clinical trials. In animal studies, insulin-like growth factor binding protein 2 (IGFBP2) shows both IGF1-dependent and IGF1-independent pharmacological effects, and IGFBP2 expression is upregulated by rough-and-tumble play that induces resilience to stress. IGFBP2 was evaluated in Porsolt, contextual fear conditioning, and chronic unpredictable stress models of posttraumatic stress disorder. The dependence of IGFBP2 effects on IGF1- and AMPA-receptor activation was tested using selective receptor antagonists. Dendritic spine morphology was measured in the dentate gyrus and the medial prefrontal cortex 24 hours after in vivo dosing. IGFBP2 was 100 times more potent than IGF1 in the Porsolt test. Unlike IGF1, effects of IGFBP2 were not blocked by the IGF1-receptor antagonist JB1, or by the AMPA-receptor antagonist 2,3-Dioxo-6-nitro-1,2,3,4 tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX) in the Porsolt test. IGFBP2 (1 µg/kg) and IGF1 (100 µg/kg i.v.) each facilitated contextual fear extinction and consolidation. Using a chronic unpredictable stress paradigm, IGFBP2 reversed stress-induced effects in the Porsolt, novelty-induced hypophagia, sucrose preference, and ultrasonic vocalization assays. IGFBP2 also increased mature dendritic spine densities in the medial prefrontal cortex and hippocampus 24 hours postdosing. These data suggest that IGFBP2 has therapeutic-like effects in multiple rat models of posttraumatic stress disorder via a novel IGF1 receptor-independent mechanism. These data also suggest that the long-lasting effects of IGFBP2 may be due to facilitation of structural plasticity at the dendritic spine level. IGFBP2 and mimetics may have therapeutic potential for the treatment of posttraumatic stress disorder

  6. Common Mechanism of Pathogenesis in Gastrointestinal Diseases Implied by Consistent Efficacy of Single Chinese Medicine Formula: A PRISMA-Compliant Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Ling, Wei; Li, Yang; Jiang, Wei; Sui, Yi; Zhao, Hai-Lu

    2015-07-01

    = 2989; OR = 3.94, 95% CI = 3.17-4.90). The relapse rate was 12.9% for SNS, significantly <46.5% for conventional therapies (OR = 0.16, 95% CI = 0.11-0.25).The consistent efficacy of the single TCM formula implicates common mechanisms of pathogenesis in GI disorders.

  7. A single-step synthesis and the kinetic mechanism for monodisperse and hexagonal-phase NaYF4:Yb, Er upconversion nanophosphors.

    Science.gov (United States)

    Shan, Jingning; Ju, Yiguang

    2009-07-08

    A single-step synthesis for monodisperse and hexagonal-phase (beta) NaYF(4):Yb, Er upconversion nanophosphors (UCNPs) with a consistent hexagonal prism shape in the size range from 18 to 200 nm was achieved. The kinetic mechanisms for the particle phase transition and growth were examined. The beta-UCNPs were obtained via co-thermolysis of trifluoroacetate precursors in octadecene (ODE) with combined ligands of oleic acid (OA) and trioctylphosphine (TOP). The experimental results showed that the combined OA-TOP ligand was crucial for changing the surface energy and controlling the particle shape over a broad size range. It was found that the particle sizes could be controlled by varying the molar ratios of Na(CF(3)COO)/Re(CF(3)COO)(3) (Re = Y, Yb, and Er). A high Na/Re ratio accelerated the cubic-phase (alpha)-->beta transition and promoted the growth of smaller beta-UCNPs. The formation of beta-UCNPs was classified into kinetic and diffusion controlled stages, depending on the reaction temperature and the dominant crystalline phases formed in each stage. In stage I, 250-310 degrees C, NaF generation was the limiting step and alpha-UCNPs were formed via a 'burst of nucleation'. In stage II, above 310 degrees C, the alpha-UCNPs formed were re-dissolved and the growth of beta-UCNPs was a diffusion controlled process governed by the Gibbs-Thompson effect. A quasi-steady-state species assumption for NaF and a chemical potential equilibrium in the solution were introduced to explain the particle size dependence on Na/Re ratios. The study of UC luminescence showed that the UC intensity was proportional to the sizes of the beta-UCNPs.

  8. Mechanical Model of Geometric Cell and Topological Algorithm for Cell Dynamics from Single-Cell to Formation of Monolayered Tissues with Pattern

    KAUST Repository

    Kachalo, Sëma

    2015-05-14

    Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues). Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software is publicly

  9. Mechanical model of geometric cell and topological algorithm for cell dynamics from single-cell to formation of monolayered tissues with pattern.

    Directory of Open Access Journals (Sweden)

    Sëma Kachalo

    Full Text Available Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues. Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software

  10. Mechanisms of deep brain stimulation

    Science.gov (United States)

    Cheng, Jennifer J.; Eskandar, Emad N.

    2015-01-01

    Deep brain stimulation (DBS) is widely used for the treatment of movement disorders including Parkinson's disease, essential tremor, and dystonia and, to a lesser extent, certain treatment-resistant neuropsychiatric disorders including obsessive-compulsive disorder. Rather than a single unifying mechanism, DBS likely acts via several, nonexclusive mechanisms including local and network-wide electrical and neurochemical effects of stimulation, modulation of oscillatory activity, synaptic plasticity, and, potentially, neuroprotection and neurogenesis. These different mechanisms vary in importance depending on the condition being treated and the target being stimulated. Here we review each of these in turn and illustrate how an understanding of these mechanisms is inspiring next-generation approaches to DBS. PMID:26510756

  11. Prevalence of obesity and the effect on length of mechanical ventilation and length of stay in intensive care patients: A single site observational study.

    Science.gov (United States)

    Dennis, Diane M; Bharat, Chrianna; Paterson, Timothy

    2017-05-01

    To provide a snapshot of the prevalence of abnormal body mass index (BMI) in a sample of intensive care unit (ICU) patients; to identify if any medical specialty was associated with abnormal BMI and to explore associations between BMI and ICU-related outcomes. Obesity is an escalating public health issue across developed nations but there is little data pertaining to critically ill patients who require care that is expensive. Retrospective observational audit of 735 adult patients (median age 58 years) admitted to the Sir Charles Gairdner Hospital 23 bed tertiary ICU between November 2012 and June 2014. Primary outcome measure was patient BMI: underweight (obese (30-39.99kg/m 2 ) or extreme obese (40kg/m 2 or above). Other measures included gender, acute physiology and chronic health evaluation II score, admission specialty, length of mechanical ventilation (MV), length of stay (LOS) and mortality. Compared to the general population there was a higher proportion of obese patients within the cohort with the majority of patients overweight (33.9%) or obese (36.5%) and median BMI of 27.9 (IQR 7.9). There were no significant differences between specialties for BMI (p=0.103) and abnormal BMI was not found to impact negatively on mortality (ICU, p=0.373; hospital, p=0.330). Normal BMI patients had shorter length of MV than other BMI categories and the impact of BMI on ICU LOS was dependent on length of MV. Overweight patients ventilated for five days or more had a shorter LOS, and extremely obese non-ventilated patients had a longer LOS, compared to normal weight patients. Although the obesity-disease relationship is increasingly complex and data presented reflects categorical BMI for patients admitted to a single ICU site it may be important to consider the cost implications of caring for this cohort especially with regard to MV and LOS. Copyright © 2016 Australian College of Critical Care Nurses Ltd. Published by Elsevier Ltd. All rights reserved.

  12. Comparison of the Mechanical Characteristics of a Universal Small Biplane Plating Technique Without Compression Screw and Single Anatomic Plate With Compression Screw.

    Science.gov (United States)

    Dayton, Paul; Ferguson, Joe; Hatch, Daniel; Santrock, Robert; Scanlan, Sean; Smith, Bret

    2016-01-01

    To better understand the mechanical characteristics of biplane locked plating in small bone fixation, the present study compared the stability under cyclic cantilever loading of a 2-plate locked biplane (BPP) construct without interfragmentary compression with that of a single-plate locked construct with an additional interfragmentary screw (SPS) using surrogate bone models simulating Lapidus arthrodesis. In static ultimate plantar bending, the BPP construct failed at significantly greater load than did the SPS construct (556.2 ± 37.1 N versus 241.6 ± 6.3 N, p = .007). For cyclic failure testing in plantar bending at a 180-N starting load, the BPP construct failed at a significantly greater number of cycles (158,322 ± 50,609 versus 13,718 ± 10,471 cycles) and failure load (242.5 ± 25.0 N versus 180.0 ± 0.0 N) than the SPS construct (p = .002). For cyclic failure testing in plantar bending at a 120-N starting load, the results were not significantly different between the BPP and SPS constructs for the number of cycles (207,646 ± 45,253 versus 159,334 ± 69,430) or failure load (205.0 ± 22.4 N versus 185.0 ± 33.5 N; p = .300). For cyclic testing with 90° offset loading (i.e., medial to lateral bending) at a 120-N starting load, all 5 BPP constructs (tension side) and 2 of the 5 SPS constructs reached 250,000 cycles without failure. Overall, the present study found the BPP construct to have superior or equivalent stability in multiplanar orientations of force application in both static and fatigue testing. Thus, the concept of biplane locked plating, using 2 low profile plates and unicortical screw insertion, shows promise in small bone fixation, because it provides consistent stability in multiplanar orientations, making it universally adaptable to many clinical situations. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  13. Federal Funding Accountability and Transparency Act

    Science.gov (United States)

    Public Law 109-282, the Federal Funding Accountability and Transparency Act of 2006 as amended (FFATA), requires disclosure of all entities and organizations receiving Federal funds through a single publicly accessible website.

  14. Acting together: Mechanisms of intentional coordination

    NARCIS (Netherlands)

    Vesper, C.

    2013-01-01

    Coordination with other people is a central part of human life. Whenever we wave at a friend, help our neighbor carry her shopping bag up the stairs, dance tango or talk to one another, we need to take another person’s actions into account and accordingly adapt how we do our part in the interaction.

  15. Atomic Energy Commission Act, 2000 (Act 588)

    International Nuclear Information System (INIS)

    2000-01-01

    Act 588 of the Republic of Ghana entitled, Atomic Energy Commission Act, 2000, amends and consolidates the Atomic Energy Commission Act, 204 of 1963 relating to the establishment of the Atomic Energy Commission. Act 588 makes provision for the Ghana Atomic Energy Commission to establish more institutes for the purpose of research in furtherance of its functions and also promote the commercialization of its research and development results. (E.A.A.)

  16. Potential mechanisms explaining why hydrolyzed casein-based diets outclass single amino acid-based diets in the prevention of autoimmune diabetes in diabetes-prone BB rats

    NARCIS (Netherlands)

    Visser, J. T. J.; Bos, N. A.; Harthoorn, L. F.; Stellaard, F.; Beijer-Liefers, S.; Rozing, J.; van Tol, E. A. F.

    Background It remains controversial whether avoidance of dietary diabetogenic triggers, such as cow's milk proteins, can prevent type 1 diabetes in genetically susceptible individuals. Here, different extensive casein hydrolysates (HC) and single amino acid (AA) formulations were tested for their

  17. Mg2+-Dependent High Mechanical Anisotropy of Three-Way-Junction pRNA as Revealed by Single-Molecule Force Spectroscopy.

    Science.gov (United States)

    Sun, Yang; Di, Weishuai; Li, Yiran; Huang, Wenmao; Wang, Xin; Qin, Meng; Wang, Wei; Cao, Yi

    2017-08-01

    Mechanical anisotropy is ubiquitous in biological tissues but is hard to reproduce in synthetic biomaterials. Developing molecular building blocks with anisotropic mechanical response is the key towards engineering anisotropic biomaterials. The three-way-junction (3WJ) pRNA, derived from ϕ29 DNA packaging motor, shows strong mechanical anisotropy upon Mg 2+ binding. In the absence of Mg 2+ , 3WJ-pRNA is mechanically weak without noticeable mechanical anisotropy. In the presence of Mg 2+ , the unfolding forces can differ by more than 4-fold along different pulling directions, ranging from about 47 pN to about 219 pN. Mechanical anisotropy of 3WJ-pRNA stems from pulling direction dependent cooperativity for the rupture of two Mg 2+ binding sites, which is a novel mechanism for the mechanical anisotropy of biomacromolecules. It is anticipated that 3WJ-pRNA can be used as a key element for the construction of biomaterials with controllable mechanical anisotropy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Mechanisms of adaptation from a multiple to a single step recovery strategy following repeated exposure to forward loss of balance in older adults.

    Directory of Open Access Journals (Sweden)

    Christopher P Carty

    Full Text Available When released from an initial, static, forward lean angle and instructed to recover with a single step, some older adults are able to meet the task requirements, whereas others either stumble or fall. The purpose of the present study was to use the concept of margin of stability (MoS to investigate balance recovery responses in the anterior-posterior direction exhibited by older single steppers, multiple steppers and those that are able to adapt from multiple to single steps following exposure to repeated forward loss of balance. One hundred and fifty-one healthy, community dwelling, older adults, aged 65-80 years, participated in the study. Participants performed four trials of the balance recovery task from each of three initial lean angles. Balance recovery responses in the anterior-posterior direction were quantified at three events; cable release (CR, toe-off (TO and foot contact (FC, for trials performed at the intermediate lean angle. MoS was computed as the anterior-posterior distance between the forward boundary of the Base of Support (BoS and the vertical projection of the velocity adjusted centre of mass position (XCoM. Approximately one-third of participants adapted from a multiple to a single step recovery strategy following repeated exposure to the task. MoS at FC for the single and multiple step trials in the adaptation group were intermediate between the exclusively single step group and the exclusively multiple step group, with the single step trials having a significant, 3.7 times higher MoS at FC than the multiple step trials. Consistent with differences between single and multiple steppers, adaptation from multiple to single steps was attributed to an increased BoS at FC, a reduced XCoM at FC and an increased rate of BoS displacement from TO to FC. Adaptations occurred within a single test session and suggest older adults that are close to the threshold of successful recovery can rapidly improve dynamic stability following

  19. Bioassay-Guided Isolation of Anti-Inflammatory Components from the Bulbs of Lilium brownii var. viridulum and Identifying the Underlying Mechanism through Acting on the NF-κB/MAPKs Pathway.

    Science.gov (United States)

    Ma, Ting; Wang, Zhen; Zhang, Yang-Mei; Luo, Jian-Guang; Kong, Ling-Yi

    2017-03-23

    The bulbs of Lilium brownii var. viridulum (LB) are commonly used as both traditional Chinese medicines and popular functional food for many centuries in China. Previous studies reported that the extract of lily bulbs exhibited anti-inflammatory activity both in vivo and in vitro, but its active components and associated molecular mechanisms remain elusive. In the present study, using bioassay-guided isolation method, two phenylpropenoid acylglycerols, 1- O -feruloyl-2- O - p -coumaroylglycerol ( 1 ) and 1,3- O -diferuloylglycerol ( 2 ), were obtained and identified from the chloroform fraction of LB. Both compounds 1 and 2 significantly decreased the production of nitrite oxide (NO) in lipopolysaccharide (LPS)-stimulated mouse macrophage RAW264.7 cells in a dose-dependent manner with half maximal inhibitory concentration (IC 50 ) values of 9.12 ± 0.72 μM and 12.01 ± 1.07 μM, respectively. They also inhibited the production of prostaglandin E2 (PGE2) and several other pro-inflammatory cytokines, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Furthermore, compounds 1 and 2 downregulated the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). They also inhibited the nuclear translocation of nuclear factor-κB (NF-κB) p65 subunit and suppressed mitogen-activated protein kinases (MAPKs) pathway. Taken these data together, compounds 1 and 2 exhibited anti-inflammatory activities through acting on the NF-κB and MAPKs pathway. This research provides the first evidence on the major bioactive constituents and related molecular mechanisms of LB as an anti-inflammatory agent. Our findings also advanced the understanding of LB as a traditional herbal medicine for the prevention and treatment of inflammation.

  20. Solid-state flow, mechanical alloying, and melt-related phenomena for [001] single-crystal tungsten ballistic rod penetrators interacting with steel targets

    Science.gov (United States)

    Pizana, Carlos

    This research program consists of a detailed microstructural investigation of in-target, single-crystal [001], clad (with Inconel 718) and unclad, W long-rod, ballistic penetrators. The rods were shot into rolled homogeneous armor (RHA) steel targets approximately 76 mm in thickness at impact velocities ranging from 1100 m/s to 1350 m/s. A comprehensive microstructural overview of the penetration process was obtained from this investigation. Solid-state flow/erosion, solid-state target/rod mixing as well as influencing factors such as strain rate, penetration performance, cladding interference and the interaction between target and projectile were emphasized. Some of the microstructural features observed, including deformation twins, cleaving, adiabatic shear bands and DRX support an overall solid-state penetration process. Furthermore they provide for a unifying perspective for the applicability of the hydrodynamic paradigm (DOP ≈ l∘rp/rt ) and earlier mechanistic erosion approaches. DRX and grain growth within adiabatic shear bands observed at specific high strain/strain-rate zones within the rods suggest that the projectile erodes by means of these microstructures in a solid-state form. This erosion process contributes to the performance of the rod by either allowing optimum flow of rod material which would increase penetration depth, or by maximizing rod material consumption which would reduce it. Since flow and/or erosion are also necessary in the target for perforation to occur, it is not surprising that the erosion process in the target was observed to mirror the one in the projectile. That is both target and projectile developed erosion zones with DRX facilitating the extreme deformation via dense overlapping shear band formation. Mechanical alloying and/or mixing of the target (steel) and rod (W, or W-Inconel 718) was also observed and investigated. Selective etching techniques as well as energy-dispersive x-ray mapping revealed unambiguous evidence of

  1. Transient receptor potential cation channel A1 (TRPA1) mediates decrements in cardiac mechanical function and dysrhythmia caused by a single air pollution exposure in mice

    Science.gov (United States)

    This work, which will be presented at SOT 2014, demonstrates that a single exposure to either ozone or acrolein causes decrements in cardiac function and altered electrical activity (i.e. arrhythmia). The results suggest that this effect is mediated by the airway sensor TRPA1. ...

  2. Mechanical properties of mammalian single smooth muscle cells. II. Evaluation of a modified technique for attachment of cells to the measurement apparatus

    NARCIS (Netherlands)

    J.J. Glerum (Jacobus); R. van Mastrigt (Ron)

    1990-01-01

    textabstractA method is described for attaching isolated single smooth muscle cells to an apparatus designed for measuring the longitudinal forces developed passively and actively by the cell upon straining, electrical or pharmacological stimulation. Primary attachment of the cell is based on its

  3. From single muscle fiber to whole muscle mechanics: a finite element model of a muscle bundle with fast and slow fibers.

    Science.gov (United States)

    Marcucci, Lorenzo; Reggiani, Carlo; Natali, Arturo N; Pavan, Piero G

    2017-12-01

    Muscles exhibit highly complex, multi-scale architecture with thousands of muscle fibers, each with different properties, interacting with each other and surrounding connective structures. Consequently, the results of single-fiber experiments are scarcely linked to the macroscopic or whole muscle behavior. This is especially true for human muscles where it would be important to understand of how skeletal muscles disorders affect patients' life. In this work, we developed a mathematical model to study how fast and slow muscle fibers, well characterized in single-fiber experiments, work and generate together force and displacement in muscle bundles. We characterized the parameters of a Hill-type model, using experimental data on fast and slow single human muscle fibers, and comparing experimental data with numerical simulations obtained from finite element (FE) models of single fibers. Then, we developed a FE model of a bundle of 19 fibers, based on an immunohistochemically stained cross section of human diaphragm and including the corresponding properties of each slow or fast fiber. Simulations of isotonic contractions of the bundle model allowed the generation of its apparent force-velocity relationship. Although close to the average of the force-velocity curves of fast and slow fibers, the bundle curve deviates substantially toward the fast fibers at low loads. We believe that the present model and the characterization of the force-velocity curve of a fiber bundle represents the starting point to link the single-fiber properties to those of whole muscle with FE application in phenomenological models of human muscles.

  4. t-PA power-pulse spray with rheolytic mechanical thrombectomy using cross-sectional image-guided portal vein access for single setting treatment of subacute superior mesenteric vein thrombosis

    Directory of Open Access Journals (Sweden)

    Mubin I Syed

    2018-01-01

    Full Text Available Background: Isolated superior mesenteric vein (SMV thrombosis is a rare but potentially fatal condition if untreated. Current treatments include transjugular or transhepatic approaches for rheolytic mechanical thrombectomy and subsequent infusions of thrombolytics. Tissue plasminogen activator (t-PA power-pulse spray can provide benefit in a single setting without thrombolytic infusions. Computed tomography (CT guidance for portal vein access is underutilized in this setting. Materials and Methods: Case 1 discusses acute SMV thrombosis treated with rheolytic mechanical thrombectomy alone using ultrasound guidance for portal vein access. Case 2 discusses subacute SMV thrombosis treated with the addition of t-PA power-pulse spray to the rheolytic mechanical thrombectomy, using CT guidance for portal vein access. Results: With rheolytic mechanical thrombectomy alone, the patient in Case 1 had significant improvement in abdominal pain. Follow-up CT demonstrated no residual SMV thrombosis and the patient continued to do well in long-term follow-up. With the addition of t-PA power-pulse spray to rheolytic mechanical thrombectomy, the patient in Case 2 with subacute SMV thrombosis dramatically improved postprocedure with resolution of abdominal pain. Follow-up imaging demonstrated patency to the SMV and partial resolution of thrombus. The patient continued to do well at 2-year follow-up. Conclusions: Adding t-PA power-pulse spray to rheolytic mechanical thrombectomy can provide benefit in a single setting versus mechanical thrombectomy alone and prevent the need for subsequent infusions of thrombolytic therapy. CT guidance is a useful alternative of localization for portal vein access via the transhepatic route that is nonoperator-dependent and helpful in the case of obese patients.

  5. Nuclear Regulatory Authority Act, 2015 (Act 895)

    International Nuclear Information System (INIS)

    2015-04-01

    An Act to establish a Nuclear Regulatory Authority in Ghana. This Act provides for the regulation and management of activities and practices for the peaceful use of nuclear material or energy, and to provide for the protection of persons and the environment against the harmful effects of radiation; and to ensure the effective implementation of the country’s international obligations and for related matters. This Act replaced the Radiation Protection Instrument, of 1993 (LI 1559).

  6. HASP: human acts simulation program

    International Nuclear Information System (INIS)

    Asai, Kiyoshi; Kambayashi, Shaw; Higuchi, Kenji; Kume, Etsuo; Otani, Takayuki; Fujii, Minoru; Uenaka, Junji; Fujisaki, Masahide.

    1990-01-01

    The Human Acts Simulation Program (HASP) aims computer simulations of mechanized human acts in a nuclear plant by a human shaped intelligent robot. The HASP has started as a ten-year program at Japan Atomic Energy Research Institute since 1987. The purposes of HASP are threefold as follows; development of basic and generalized design technologies for intelligent robots, development of basic technologies for an advanced intelligent and automatic nuclear power plant, and provision of artificial intelligence techniques for researchers in the nuclear field. In this paper, the contents of the HASP are described. (author)

  7. Raman excitation profiles of hybrid systems constituted by single-layer graphene and free base phthalocyanine: Manifestations of two mechanisms of graphene-enhanced Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Uhlířová, T.; Mojzeš, P.; Melníková Komínková, Zuzana; Kalbáč, Martin; Sutrová, Veronika; Šloufová, I.; Vlčková, B.

    2017-01-01

    Roč. 48, č. 10 (2017), s. 1270-1281 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:61388955 ; RVO:61389013 Keywords : graphene -enhanced Raman scattering * single-layer graphene * free base phthalocyanine * Raman excitation profiles * photoinduced charge transfer Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 2.969, year: 2016

  8. Raman excitation profiles of hybrid systems constituted by single-layer graphene and free base phthalocyanine: Manifestations of two mechanisms of graphene-enhanced Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Uhlířová, T.; Mojzeš, P.; Melníková Komínková, Zuzana; Kalbáč, Martin; Sutrová, Veronika; Šloufová, I.; Vlčková, B.

    2017-01-01

    Roč. 48, č. 10 (2017), s. 1270-1281 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:61388955 ; RVO:61389013 Keywords : graphene-enhanced Raman scattering * single-layer graphene * free base phthalocyanine * Raman excitation profiles * photoinduced charge transfer Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 2.969, year: 2016

  9. A combined experimental atomic force microscopy-based nanoindentation and computational modeling approach to unravel the key contributors to the time-dependent mechanical behavior of single cells.

    Science.gov (United States)

    Florea, Cristina; Tanska, Petri; Mononen, Mika E; Qu, Chengjuan; Lammi, Mikko J; Laasanen, Mikko S; Korhonen, Rami K

    2017-02-01

    Cellular responses to mechanical stimuli are influenced by the mechanical properties of cells and the surrounding tissue matrix. Cells exhibit viscoelastic behavior in response to an applied stress. This has been attributed to fluid flow-dependent and flow-independent mechanisms. However, the particular mechanism that controls the local time-dependent behavior of cells is unknown. Here, a combined approach of experimental AFM nanoindentation with computational modeling is proposed, taking into account complex material behavior. Three constitutive models (porohyperelastic, viscohyperelastic, poroviscohyperelastic) in tandem with optimization algorithms were employed to capture the experimental stress relaxation data of chondrocytes at 5 % strain. The poroviscohyperelastic models with and without fluid flow allowed through the cell membrane provided excellent description of the experimental time-dependent cell responses (normalized mean squared error (NMSE) of 0.003 between the model and experiments). The viscohyperelastic model without fluid could not follow the entire experimental data that well (NMSE = 0.005), while the porohyperelastic model could not capture it at all (NMSE = 0.383). We also show by parametric analysis that the fluid flow has a small, but essential effect on the loading phase and short-term cell relaxation response, while the solid viscoelasticity controls the longer-term responses. We suggest that the local time-dependent cell mechanical response is determined by the combined effects of intrinsic viscoelasticity of the cytoskeleton and fluid flow redistribution in the cells, although the contribution of fluid flow is smaller when using a nanosized probe and moderate indentation rate. The present approach provides new insights into viscoelastic responses of chondrocytes, important for further understanding cell mechanobiological mechanisms in health and disease.

  10. Mechanical, Thermal, and Electrical Energy Storage in a Single Working Body: Electrification and Thermal Effects upon Pressure-Induced Water Intrusion-Extrusion in Nanoporous Solids.

    Science.gov (United States)

    Grosu, Yaroslav; Mierzwa, Michał; Eroshenko, Valentine A; Pawlus, Sebastian; Chorażewski, Mirosław; Nedelec, Jean-Marie; Grolier, Jean-Pierre E

    2017-03-01

    This paper presents the first experimental evidence of pronounced electrification effects upon reversible cycle of forced water intrusion-extrusion in nanoporous hydrophobic materials. Recorded generation of electricity combined with high-pressure calorimetric measurements improves the energy balance of {nanoporous solid + nonwetting liquid} systems by compensating mechanical and thermal energy hysteresis in the cycle. Revealed phenomena provide a novel way of "mechanical to electrical" and/or "thermal to electrical" energy transformation with unprecedented efficiency and additionally open a perspective to increase the efficiency of numerous energy applications based on such systems taking advantage of electricity generation during operational cycle.

  11. Respiratory mechanics

    CERN Document Server

    Wilson, Theodore A

    2016-01-01

    This book thoroughly covers each subfield of respiratory mechanics: pulmonary mechanics, the respiratory pump, and flow. It presents the current understanding of the field and serves as a guide to the scientific literature from the golden age of respiratory mechanics, 1960 - 2010. Specific topics covered include the contributions of surface tension and tissue forces to lung recoil, the gravitational deformation of the lung, and the interdependence forces that act on pulmonary airways and blood vessels. The geometry and kinematics of the ribs is also covered in detail, as well as the respiratory action of the external and internal intercostal muscles, the mechanics of the diaphragm, and the quantitative compartmental models of the chest wall is also described. Additionally, flow in the airways is covered thoroughly, including the wave-speed and viscous expiratory flow-limiting mechanisms; convection, diffusion and the stationary front; and the distribution of ventilation. This is an ideal book for respiratory ...

  12. Levels of Reflective Thinking and Patient Safety: An Investigation of the Mechanisms that Impact on Student Learning in a Single Cohort over a 5 Year Curriculum

    Science.gov (United States)

    Ambrose, Lucy J.; Ker, Jean S.

    2014-01-01

    Existing research into learning about patient safety focuses on identifying how educational interventions improve educational outcomes but few studies offer evidence that inform educators about the mechanisms involved in learning about patient safety. The current evidence based in undergraduates is also limited to outcomes that relate to knowledge…

  13. The predictive value of single nucleotide polymorphisms in the VEGF system to the efficacy of first-line treatment with bevacizumab plus chemotherapy in patients with metastatic colorectal cancer : Results from the Nordic ACT trial

    DEFF Research Database (Denmark)

    Hansen, Torben Frøstrup; Christensen, René Depont; Andersen, Rikke Fredslund

    2012-01-01

    PURPOSE: Bevacizumab and chemotherapy is a common choice for first-line treatment of metastatic colorectal cancer (mCRC). So far, no predictive markers have been identified. The aim was to investigate the possible predictive value of single nucleotide polymorphisms (SNPs) in the vascular endothel......PURPOSE: Bevacizumab and chemotherapy is a common choice for first-line treatment of metastatic colorectal cancer (mCRC). So far, no predictive markers have been identified. The aim was to investigate the possible predictive value of single nucleotide polymorphisms (SNPs) in the vascular...... endothelial growth factor (VEGF) system in this setting. METHODS: Pre-treatment blood samples and response evaluations were available from 218 of the 249 included patients. All patients received bevacizumab and chemotherapy comprising fluorouracil and leucovorin or capecitabine combined with either...... marker for bevacizumab plus chemotherapy in patients with mCRC. Patients with the A allele appeared to have increased response rates. The results call for validation....

  14. Experimental techniques for single cell and single molecule biomechanics

    International Nuclear Information System (INIS)

    Lim, C.T.; Zhou, E.H.; Li, A.; Vedula, S.R.K.; Fu, H.X.

    2006-01-01

    Stresses and strains that act on the human body can arise either from external physical forces or internal physiological environmental conditions. These biophysical interactions can occur not only at the musculoskeletal but also cellular and molecular levels and can determine the health and function of the human body. Here, we seek to investigate the structure-property-function relationship of cells and biomolecules so as to understand their important physiological functions as well as establish possible connections to human diseases. With the recent advancements in cell and molecular biology, biophysics and nanotechnology, several innovative and state-of-the-art experimental techniques and equipment have been developed to probe the structural and mechanical properties of biostructures from the micro- down to picoscale. Some of these experimental techniques include the optical or laser trap method, micropipette aspiration, step-pressure technique, atomic force microscopy and molecular force spectroscopy. In this article, we will review the basic principles and usage of these techniques to conduct single cell and single molecule biomechanics research

  15. Atomic Act amended

    International Nuclear Information System (INIS)

    Drabova, D.

    2002-01-01

    In the paper by the chairwoman of the Czech nuclear regulatory authority, the history of Czech nuclear legislation is outlined, the reasons for the amendment of the Atomic Act (Act No. 18/1997) are explained, and the amendments themselves are highlighted. The Act No. 13/2002 of 18 December 2001 is reproduced from the official Collection of Acts of the Czech Republic in the facsimile form. The following acts were thereby amended: Atomic Act No. 18/1997, Metrology Act No. 505/1990, Public Health Protection Act No. 258/2000, and Act No. 2/1969 on the Establishment of Ministries and Other Governmental Agencies of the Czech Republic. (P.A.)

  16. Two-component regulatory system ActS/ActR is required for Sinorhizobium meliloti adaptation to oxidative stress.

    Science.gov (United States)

    Tang, Guirong; Wang, Sunjun; Lu, Dawei; Huang, Leqi; Li, Ningning; Luo, Li

    2017-05-01

    The two-component system ActS/ActR plays important roles in bacterial adaptation to abiotic stress, including acid tolerance and oxidant resistance. However, the underlying regulatory mechanism is not clear. In this study, we found that the ActS/ActR system is required for adaptation to oxidative stress by regulating the transcription of the genes actR, katB, gshA and gshB1. The actS and actR mutants were sensitive to low pH and oxidants such as H 2 O 2 , oxidized glutathione (GSSG) and sodium nitroprusside (SNP). The expression of actR by using a plasmid rescued the defect of SNP sensitivity for all actS and actR mutants. The expression of actS and actR were suppressed by treatment with H 2 O 2 . The expression of actS, actR, oxyR, katA and katB was required for ActS and ActR under normal conditions. The induction of katB, gshA and gshB1 depended on ActS and ActR during treatment with H 2 O 2 and SNP. Our findings revealed that the ActS/ActR system is a key redox regulator in S. meliltoi and provides a new cue to understanding Rhizobium-legume symbiosis. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  17. Current-Transport Mechanisms in the AlInN/AlN/GaN single-channel and AlInN/AlN/GaN/AlN/GaN double-channel heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, Engin, E-mail: engina@bilkent.edu.tr [Nanotechnology Research Center, Department of Physics, Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, 06800 Ankara (Turkey); Turan, Sevil; Gökden, Sibel; Teke, Ali [Department of Physics, Faculty of Science and Letters, Balıkesir University, Çağış Kampüsü, 10145 Balıkesir (Turkey); Özbay, Ekmel [Nanotechnology Research Center, Department of Physics, Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, 06800 Ankara (Turkey)

    2013-12-02

    Current-transport mechanisms were investigated in Schottky contacts on AlInN/AlN/GaN single channel (SC) and AlInN/AlN/GaN/AlN/GaN double channel (DC) heterostructures. A simple model was adapted to the current-transport mechanisms in DC heterostructure. In this model, two Schottky diodes are in series: one is a metal–semiconductor barrier layer (AIInN) Schottky diode and the other is an equivalent Schottky diode, which is due to the heterojunction between the AlN and GaN layer. Capacitance–voltage studies show the formation of a two-dimensional electron gas at the AlN/GaN interface in the SC and the first AlN/GaN interface from the substrate direction in the DC. In order to determine the current mechanisms for SC and DC heterostructures, we fit the analytical expressions given for the tunneling current to the experimental current–voltage data over a wide range of applied biases as well as at different temperatures. We observed a weak temperature dependence of the saturation current and a fairly small dependence on the temperature of the tunneling parameters in this temperature range. At both a low and medium forward-bias voltage values for Schottky contacts on AlInN/AlN/GaN/AlN/GaN DC and AlInN/AlN/GaN SC heterostructures, the data are consistent with electron tunneling to deep levels in the vicinity of mixed/screw dislocations in the temperature range of 80–420 K. - Highlights: • Current mechanisms were investigated on single and double channel heterostructures. • A model was adapted to the current mechanisms in double channel heterostructures. • We observed a weak temperature dependence of the saturation current. • And a small dependence of the tunneling parameters in this temperature range.

  18. Current-Transport Mechanisms in the AlInN/AlN/GaN single-channel and AlInN/AlN/GaN/AlN/GaN double-channel heterostructures

    International Nuclear Information System (INIS)

    Arslan, Engin; Turan, Sevil; Gökden, Sibel; Teke, Ali; Özbay, Ekmel

    2013-01-01

    Current-transport mechanisms were investigated in Schottky contacts on AlInN/AlN/GaN single channel (SC) and AlInN/AlN/GaN/AlN/GaN double channel (DC) heterostructures. A simple model was adapted to the current-transport mechanisms in DC heterostructure. In this model, two Schottky diodes are in series: one is a metal–semiconductor barrier layer (AIInN) Schottky diode and the other is an equivalent Schottky diode, which is due to the heterojunction between the AlN and GaN layer. Capacitance–voltage studies show the formation of a two-dimensional electron gas at the AlN/GaN interface in the SC and the first AlN/GaN interface from the substrate direction in the DC. In order to determine the current mechanisms for SC and DC heterostructures, we fit the analytical expressions given for the tunneling current to the experimental current–voltage data over a wide range of applied biases as well as at different temperatures. We observed a weak temperature dependence of the saturation current and a fairly small dependence on the temperature of the tunneling parameters in this temperature range. At both a low and medium forward-bias voltage values for Schottky contacts on AlInN/AlN/GaN/AlN/GaN DC and AlInN/AlN/GaN SC heterostructures, the data are consistent with electron tunneling to deep levels in the vicinity of mixed/screw dislocations in the temperature range of 80–420 K. - Highlights: • Current mechanisms were investigated on single and double channel heterostructures. • A model was adapted to the current mechanisms in double channel heterostructures. • We observed a weak temperature dependence of the saturation current. • And a small dependence of the tunneling parameters in this temperature range

  19. Some Calculated (p,α Cross-Sections Using the Alpha Particle Knock-On and Triton Pick-Up Reaction Mechanisms: An Optimisation of the Single-Step Feshbach–Kerman–Koonin (FKK Theory

    Directory of Open Access Journals (Sweden)

    Felix S. Olise

    2016-04-01

    Full Text Available The Feshbach–Kerman–Koonin (FKK multi-step direct (MSD theory of pre-equilibrium reactions has been used to compute the single-step cross-sections for some (p,α reactions using the knock-on and pick-up reaction mechanisms at two incident proton energies. For the knock-on mechanism, the reaction was assumed to have taken place by the direct ejection of a preformed alpha cluster in a shell-model state of the target. But the reaction was assumed to have taken place by the pick-up of a preformed triton cluster (also bound in a shell-model state of the target core by the incident proton for the pick-up mechanism. The Yukawa forms of potential were used for the proton-alpha (for the knock-on process and proton-triton (for the pick-up process interaction and several parameter sets for the proton and alpha-particle optical potentials. The calculated cross-sections for both mechanisms gave satisfactory fits to the experimental data. Furthermore, it has been shown that some combinations of the calculated distorted wave Born approximation cross-sections for the two reaction mechanisms in the FKK MSD theory are able to give better fits to the experimental data, especially in terms of range of agreement. In addition, the theory has been observed to be valid over a wider range of energy.

  20. [The effect of the inhalation of a single atrovent dose on pulmonary ventilation function and respiratory mechanics in patients with chronic obstructive bronchitis].

    Science.gov (United States)

    Tetenev, F F; Cherniavskaia, G M

    1989-01-01

    A study was made of the action of inhalation of a single atrovent dose in 20 patients with chronic obstructive bronchitis. All the patients demonstrated a considerable abatement or disappearance of dyspnea, and a reduction of the number of dry rales. The vital capacity of the lungs, the volume of forced expiration, maximal pulmonary ventilation, MOCmax, MOC50, and MOC75 substantially increased. The respiratory work diminished on the average by 32.3% primarily due to the lessening of non-elastic lung resistance. The rise of pulmonary static extensibility and reduction of pulmonary elastic propulsion were recorded. In patients with and without clinical signs of bronchospasm, the action of atrovent was identical.

  1. Clinical Factors Associated With Adherence to the Premedication Protocol for Withdrawal of Mechanical Ventilation in Terminally Ill Patients: A 4-Year Experience at a Single Medical Center in Asia.

    Science.gov (United States)

    Wang, Chao-Hui; Huang, Pei-Wei; Hung, Chia-Yen; Lee, Shu-Hui; Kao, Chen-Yi; Wang, Hung-Ming; Hung, Yu-Shin; Su, Po-Jung; Kuo, Yung-Chia; Hsieh, Chia-Hsun; Chou, Wen-Chi

    2018-05-01

    Data on end-of-life care practices in Asia are scarce. This study aimed to analyze the clinical factors associated with the recommended premedication protocol for mechanical ventilation withdrawal, in Taiwan. A total of 135 terminally ill patients who had mechanical ventilation withdrawn between 2013 and 2016 from a single medical center in Taiwan were enrolled. A premedication protocol of morphine and midazolam intravenous bolus was routinely recommended for the patients before mechanical ventilation withdrawal. Receipt of opioids and/or benzodiazepines during the withdrawal process was defined as full (both), partial (1 drug), and no (none) adherence. The clinical factors relevant to the adherence of recommended premedication protocol for mechanical ventilation withdrawal were analyzed. Overall, 126 (93.3%) patients died, 8 (5.9%) patients were transferred to other institutions for further care, and 1 (0.7%) patient was discharged to home after mechanical ventilation withdrawal. The median survival time was 45 minutes, and 102 (75.6%) patients died within 1 day after the withdrawal process. The full, partial, and no adherence rates for premedication guideline were 17.8%, 40.0%, and 42.2%, respectively. The main diagnosis of cancer, receipt of hospice care, and preservation of spontaneous respiration were independent variables associated with the partial or full adherence to the premedication protocol. Our data show that adherence to the premedication protocol for mechanical ventilation withdrawal in terminally ill patients was inadequate in Taiwan. Promoting hospice care and educating medical personnel in the compassionate withdrawal of mechanical ventilation, especially in patients with noncancer disease, are warranted.

  2. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... Treatments and Therapies Airway Clearance Airway Clearance Techniques (ACTs) There are different ways to clear your airways. ... or caregiver. Older kids and adults can choose ACTs that they can do on their own. Share ...

  3. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... Open Enrollment Periods Claims and Appeals Glossary of Common Health Insurance Terms Understanding Travel Insurance Research X ... with CF and her father: Demonstrate and discuss common ACT therapies Offer their tips for fitting ACTs ...

  4. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... CF Treatments and Therapies Airway Clearance Airway Clearance Techniques (ACTs) There are different ways to clear your ... for fitting ACTs into daily life Airway Clearance Techniques | Webcast To learn more about how you can ...

  5. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... Therapeutics Lab Developing New Treatments The CF Foundation offers a number of resources for learning about clinical ... her father: Demonstrate and discuss common ACT therapies Offer their tips for fitting ACTs into daily life ...

  6. Airway Clearance Techniques (ACTs)

    Medline Plus

    Full Text Available ... the smaller airways to attack bacteria. Choose What's Best for You Your respiratory therapist or another member ... specific ACTs for you to try. However, the best ACT is the one that you are most ...

  7. Mechanisms of gas bubble retention and release: results for Hanford Waste Tanks 241-S-102 and 241-SY-103 and single-shell tank simulants

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, P.A.; Rassat, S.D.; Bredt, P.R.; Konynenbelt, J.H.; Tingey, S.M.; Mendoza, D.P.

    1996-09-01

    Research at Pacific Northwest National Laboratory (PNNL) has probed the physical mechanisms and waste properties that contribute to the retention and release of flammable gases from radioactive waste stored in underground tanks at Hanford. This study was conducted for Westinghouse Hanford Company as part of the PNNL Flammable Gas Project. The wastes contained in the tanks are mixes of radioactive and chemical products, and some of these wastes are known to generate mixtures of flammable gases, including hydrogen, nitrous oxide, and ammonia. Because these gases are flammable, their retention and episodic release pose a number of safety concerns.

  8. Mechanisms of gas bubble retention and release: results for Hanford Waste Tanks 241-S-102 and 241-SY-103 and single-shell tank simulants

    International Nuclear Information System (INIS)

    Gauglitz, P.A.; Rassat, S.D.; Bredt, P.R.; Konynenbelt, J.H.; Tingey, S.M.; Mendoza, D.P.

    1996-09-01

    Research at Pacific Northwest National Laboratory (PNNL) has probed the physical mechanisms and waste properties that contribute to the retention and release of flammable gases from radioactive waste stored in underground tanks at Hanford. This study was conducted for Westinghouse Hanford Company as part of the PNNL Flammable Gas Project. The wastes contained in the tanks are mixes of radioactive and chemical products, and some of these wastes are known to generate mixtures of flammable gases, including hydrogen, nitrous oxide, and ammonia. Because these gases are flammable, their retention and episodic release pose a number of safety concerns

  9. Nuclear Installations Act 1965

    International Nuclear Information System (INIS)

    1965-01-01

    This Act governs all activities related to nuclear installations in the United Kingdom. It provides for the licensing procedure for nuclear installations, the duties of licensees, the competent authorities and carriers of nuclear material in respect of nuclear occurrences, as well as for the system of third party liability and compensation for nuclear damage. The Act repeals the Nuclear Installations (Licensing and Insurance) Act 1959 and the Nuclear Installations (Amendment Act) 1965 except for its Section 17(2). (NEA) [fr

  10. Deep soft-tissue massage applied to healthy calf muscle has no effect on passive mechanical properties: a randomized, single-blind, cross-over study.

    Science.gov (United States)

    Thomson, Daniel; Gupta, Amitabh; Arundell, Jesica; Crosbie, Jack

    2015-01-01

    Massage is often applied with the intention of improving flexibility or reducing stiffness in musculotendinous tissue. There is, however, a lack of supporting evidence that such mechanical effects occur. The purpose of the study was to investigate the effect of massage on the passive mechanical properties of the calf muscle complex. Twenty nine healthy volunteers aged between 18 and 45 years of age had their calf muscle compliance and ankle joint dorsiflexion range of motion (ROM) measured using an instrumented footplate before, immediately and 30 minutes after a ten minute application of deep massage or superficial heating to the calf muscle complex. Repeated measures analysis of variance was used to determine differences between testing sessions and the types of intervention. Reliability testing for the measurement method was conducted using analysis of variance both within and between testing sessions. There was no significant change in calf muscle stiffness or ankle dorsiflexion range of motion with or without the application of calf massage. Inter- and intra-session reliability were very high, ICC > 0.88 (p calf muscle complex. The findings of this study suggest that the use of massage to increase tissue flexibility prior to activity is not justified.

  11. Strategies to improve phase-stability of ultrafast swept source optical coherence tomography for single shot imaging of transient mechanical waves at 16 kHz frame rate

    Energy Technology Data Exchange (ETDEWEB)

    Song, Shaozhen; Wei, Wei; Hsieh, Bao-Yu; Pelivanov, Ivan; O' Donnell, Matthew [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Shen, Tueng T.; Wang, Ruikang K., E-mail: wangrk@uw.edu [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Department of Ophthalmology, University of Washington, Seattle, Washington 98104 (United States)

    2016-05-09

    We present single-shot phase-sensitive imaging of propagating mechanical waves within tissue, enabled by an ultrafast optical coherence tomography (OCT) system powered by a 1.628 MHz Fourier domain mode-locked (FDML) swept laser source. We propose a practical strategy for phase-sensitive measurement by comparing the phases between adjacent OCT B-scans, where the B-scan contains a number of A-scans equaling an integer number of FDML buffers. With this approach, we show that micro-strain fields can be mapped with ∼3.0 nm sensitivity at ∼16 000 fps. The system's capabilities are demonstrated on porcine cornea by imaging mechanical wave propagation launched by a pulsed UV laser beam, promising non-contact, real-time, and high-resolution optical coherence elastography.

  12. Cryogenic separation of hydrogen isotopes in single-walled carbon and boron-nitride nanotubes: insight into the mechanism of equilibrium quantum sieving in quasi-one-dimensional pores.

    Science.gov (United States)

    Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P

    2008-07-17

    Quasi-one-dimensional cylindrical pores of single-walled boron nitride and carbon nanotubes efficiently differentiate adsorbed hydrogen isotopes at 33 K. Extensive path integral Monte Carlo simulations revealed that the mechanisms of quantum sieving for both types of nanotubes are quantitatively similar; however, the stronger and heterogeneous external solid-fluid potential generated from single-walled boron nitride nanotubes enhanced the selectivity of deuterium over hydrogen both at zero coverage and at finite pressures. We showed that this enhancement of the D(2)/H(2) equilibrium selectivity results from larger localization of hydrogen isotopes in the interior space of single-walled boron nitride nanotubes in comparison to that of equivalent single-walled carbon nanotubes. The operating pressures for efficient quantum sieving of hydrogen isotopes are strongly depending on both the type as well as the size of the nanotube. For all investigated nanotubes, we predicted the occurrence of the minima of the D(2)/H(2) equilibrium selectivity at finite pressure. Moreover, we showed that those well-defined minima are gradually shifted upon increasing of the nanotube pore diameter. We related the nonmonotonic shape of the D(2)/H(2) equilibrium selectivity at finite pressures to the variation of the difference between the average kinetic energy computed from single-component adsorption isotherms of H(2) and D(2). In the interior space of both kinds of nanotubes hydrogen isotopes formed solid-like structures (plastic crystals) at 33 K and 10 Pa with densities above the compressed bulk para-hydrogen at 30 K and 30 MPa.

  13. Effects of Vacancy Concentration and Temperature on Mechanical Properties of Single-Crystal γ-TiAl Based on Molecular Dynamics Simulation

    Science.gov (United States)

    Ruicheng, Feng; Hui, Cao; Haiyan, Li; Zhiyuan, Rui; Changfeng, Yan

    2018-01-01

    Molecular dynamics simulation is used to analyze tensile strength and elastic modulus under different temperatures and vacancy concentrations. The effects of temperature and vacancy concentration on the mechanical properties of γ-TiAl alloy are investigated. The results show that the ultimate stress, ultimate strain and elastic modulus decrease nonlinearly with increasing temperature and vacancy concentration. As the temperature increases, the plastic of material is reinforced. The influence of temperature on strength and elastic modulus is larger than that of vacancy concentration. The evolution process of vacancy could be observed clearly. Furthermore, vacancies with different concentrations develop into voids first as a function of external forces or other factors, micro cracks evolve from those voids, those micro cracks then converge to a macro crack, and fracture will finally occur. The vacancy evolution process cannot be observed clearly owing to the thermal motion of atoms at high temperature. In addition, potential energy is affected by both temperature and vacancy concentration.

  14. Spontaneous mechanical and electrical activities of human calf musculature at rest assessed by repetitive single-shot diffusion-weighted MRI and simultaneous surface electromyography.

    Science.gov (United States)

    Schwartz, Martin; Steidle, Günter; Martirosian, Petros; Ramos-Murguialday, Ander; Preißl, Hubert; Stemmer, Alto; Yang, Bin; Schick, Fritz

    2018-05-01

    Assessment of temporal and spatial relations between spontaneous mechanical activities in musculature (SMAM) at rest as revealed by diffusion-weighted imaging (DWI) and electrical muscular activities in surface EMG (sEMG). Potential influences of static and radiofrequency magnetic fields on muscular activity on sEMG measurements at rest were examined systematically. Series of diffusion-weighted stimulated echo planar imaging were recorded with concurrent sEMG measurements. Electrical activities in sEMG were analyzed by non-parametric Friedman and two-sample Kolmogorov-Smirnov test. Direct correlation of both modalities was investigated by temporal mapping of electrical activity in sEMG to DWI repetition interval. Electrical activities in sEMG and number of visible SMAMs in DWI showed a strong correlation (ρ = 0.9718). High accordance between sEMG activities and visible SMAMs in DWI in a near-surface region around sEMG electrodes was achieved. Characteristics of sEMG activities were almost similar under varying magnetic field conditions. Visible SMAMs in DWI have shown a close and direct relation to concurrent signals recorded by sEMG. MR-related magnetic fields had no significant effects on findings in sEMG. Hence, appearance of SMAMs in DWI should not be considered as imaging artifact or as effects originating from the special conditions of MR examinations. Spatial and temporal distributions of SMAMs indicate characteristics of spontaneous (microscopic) mechanical muscular action at rest. Therefore, DWI techniques should be considered as non-invasive tools for studying physiology and pathophysiology of spontaneous activities in resting muscle. Magn Reson Med 79:2784-2794, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  15. General method of analysis of kinetic equations for multistep reversible mechanisms in the single-exponential regime: application to kinetics of open complex formation between Esigma70 RNA polymerase and lambdaP(R) promoter DNA.

    Science.gov (United States)

    Tsodikov, O V; Record, M T

    1999-03-01

    A novel analytical method based on the exact solution of equations of kinetics of unbranched first- and pseudofirst-order mechanisms is developed for application to the process of Esigma70 RNA polymerase (R)-lambdaPR promoter (P) open complex formation, which is described by the minimal three-step mechanism with two kinetically significant intermediates (I1, I2), [equation: see text], where the final product is an open complex RPo. The kinetics of reversible and irreversible association (pseudofirst order, [R] > [P]) to form long-lived complexes (RPo and I2) and the kinetics of dissociation of long-lived complexes both exhibit single exponential behavior. In this situation, the analytical method provides explicit expressions relating observed rate constants to the microscopic rate constants of mechanism steps without use of rapid equilibrium or steady-state approximations, and thereby provides a basis for interpreting the composite rate constants of association (ka), isomerization (ki), and dissociation (kd) obtained from experiment for this or any other sequential mechanism of any number of steps. In subsequent papers, we apply this formalism to analyze kinetic data obtained in the reversible and irreversible binding regimes of Esigma70 RNA polymerase (R)-lambdaP(R) promoter (P) open complex formation.

  16. Mechanical characteristics of hybrid multilayer Green Tape[sup TM] ceramics sintered in a 2. 45 GHz single mode microwave cavity. [A commercial alumina-based product

    Energy Technology Data Exchange (ETDEWEB)

    Bansky, J.; Engemann, J. (Univ. of Wuppertal (Germany)); Bartley, D.; Asmussen, J.; Case, E.; Connery, S. (Michigan State Univ., East Lansing (United States))

    1993-04-01

    Research indicates that microwave energy offers many advantages over conventional heating methods. These advantages generally can be divided into two categories. One of them is the reduction in processing time and temperature, and the second one is the fabrication of materials with unique and/or superior properties. Microwave energy appears to be especially advantageous for the processing of many types of ceramics requiring high thermal process temperatures. This is connected with the increased coupling efficiency of ceramics at high temperatures with the microwave energy, the more uniform volumetric heating, and increased densification rates at lower processing temperatures. This paper describes microwave sintering of a commercial alumina-based product, Green Tape[sup TM] Dielectric 851AT (DuPont), that is designed for use as a material for hybrid integrated multilayer structures in the production of hybrid integrated circuits, as well as for some unconventional applications (ion optics, sensors, etc) (4,5). This study compares mechanical properties of conventionally and microwave sintered Green Tape[sup TM] 851AT hybrid multilayer structures.

  17. Mechanoenzymatics and Nanoassembly of Single Molecules

    Science.gov (United States)

    Puchner, Elias M.; Gaub, Hermann E.

    We investigated the muscle enzyme, titin kinase, by means of single-molecule force spectroscopy. Our results show that the binding of ATP, which is the first step of its signaling cascade controlling the muscle gene expression and protein turnover, is mechanically induced. The detailed determination of barrier positions in the mechanical activation pathway and the corresponding functional states allow structural insight, by comparing the experiment with molecular dynamics simulations. From our results, we conclude that titin kinase acts as a natural force sensor controlling the muscle build-up. To study the interplay of functional units, we developed the single-molecule cut-and-paste technique, which combines the precision of AFM with the selectivity of DNA hybridization. Functional units can be assembled one-by-one in an arbitrarily predefined pattern, with an accuracy that is better than 11 nm. The cyclic assembly process is optically monitored and mechanically recorded by force-extension traces. Using biotin as a functional unit attached to the transported DNA, patterns of binding sites may be created, to which streptavidin-modified nanoobjects like fluorescent nanoparticles can specifically self-assemble in a second step.

  18. Mechanisms of physiological adjustment of N2 fixation in Cicer arietinum L. (chickpea) during early stages of water deficit: single or multi-factor controls.

    Science.gov (United States)

    Nasr Esfahani, Maryam; Sulieman, Saad; Schulze, Joachim; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo; Tran, Lam-Son Phan

    2014-09-01

    Drought negatively impacts symbiotic nitrogen fixation (SNF) in Cicer arietinum L. (chickpea), thereby limiting yield potential. Understanding how drought affects chickpea nodulation will enable the development of strategies to biotechnologically engineer chickpea varieties with enhanced SNF under drought conditions. By analyzing carbon and nitrogen metabolism, we studied the mechanisms of physiological adjustment of nitrogen fixation in chickpea plants nodulated with Mesorhizobium ciceri during both drought stress and subsequent recovery. The nitrogenase activity, levels of several key carbon (in nodules) and nitrogen (in both nodules and leaves) metabolites and antioxidant compounds, as well as the activity of related nodule enzymes were examined in M. ciceri-inoculated chickpea plants under early drought stress and subsequent recovery. Results indicated that drought reduced nitrogenase activity, and that this was associated with a reduced expression of the nifK gene. Furthermore, drought stress promoted an accumulation of amino acids, mainly asparagine in nodules (but not in leaves), and caused a cell redox imbalance in nodules. An accumulation of organic acids, especially malate, in nodules, which coincided with the decline of nodulated root respiration, was also observed under drought stress. Taken together, our findings indicate that reduced nitrogenase activity occurring at early stages of drought stress involves, at least, the inhibition of respiration, nitrogen accumulation and an imbalance in cell redox status in nodules. The results of this study demonstrate the potential that the genetic engineering-based improvement of SNF efficiency could be applied to reduce the impact of drought on the productivity of chickpea, and perhaps other legume crops. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  19. A neuro-mechanical model of a single leg joint highlighting the basic physiological role of fast and slow muscle fibres of an insect muscle system.

    Directory of Open Access Journals (Sweden)

    Tibor Istvan Toth

    Full Text Available In legged animals, the muscle system has a dual function: to produce forces and torques necessary to move the limbs in a systematic way, and to maintain the body in a static position. These two functions are performed by the contribution of specialized motor units, i.e. motoneurons driving sets of specialized muscle fibres. With reference to their overall contraction and metabolic properties they are called fast and slow muscle fibres and can be found ubiquitously in skeletal muscles. Both fibre types are active during stepping, but only the slow ones maintain the posture of the body. From these findings, the general hypothesis on a functional segregation between both fibre types and their neuronal control has arisen. Earlier muscle models did not fully take this aspect into account. They either focused on certain aspects of muscular function or were developed to describe specific behaviours only. By contrast, our neuro-mechanical model is more general as it allows functionally to differentiate between static and dynamic aspects of movement control. It does so by including both muscle fibre types and separate motoneuron drives. Our model helps to gain a deeper insight into how the nervous system might combine neuronal control of locomotion and posture. It predicts that (1 positioning the leg at a specific retraction angle in steady state is most likely due to the extent of recruitment of slow muscle fibres and not to the force developed in the individual fibres of the antagonistic muscles; (2 the fast muscle fibres of antagonistic muscles contract alternately during stepping, while co-contraction of the slow muscle fibres takes place during steady state; (3 there are several possible ways of transition between movement and steady state of the leg achieved by varying the time course of recruitment of the fibres in the participating muscles.

  20. Mechanical arm trainer for the treatment of the severely affected arm after a stroke: a single-blinded randomized trial in two centers.

    Science.gov (United States)

    Hesse, S; Werner, C; Pohl, M; Mehrholz, J; Puzich, U; Krebs, H I

    2008-10-01

    To test whether training with a new mechanical arm trainer leads to better outcomes than electrical stimulation of the paretic wrist extensors in subacute stroke patients with severe upper limb paresis. Electrical stimulation is a standard and reimbursable form of therapy in Germany. Randomized controlled trial of 54 inpatients enrolled 4-8 wks from stroke onset, mean upper-extremity subsection of Fugl-Meyer assessment (0-66) at admission less than 18. In addition to standard care, all patients practiced 20-30 mins arm trainer or electrical stimulation every workday for 6 wks, totaling 30 sessions. Primary outcome was the Fugl-Meyer assessment, secondary outcomes were the Box and Block test, the Medical Research Council and the modified Ashworth scale, blindly assessed at enrollment, after 6 wks, and at 3-mo follow-up. Both groups were homogeneous at study onset. Shoulder pain occurred in two arm trainer patients. The primary Fugl-Meyer assessment outcome improved for both groups over time (P Fugl-Meyer assessment scores were 8.8 +/- 4.8 (19.2 +/- 14.5) for the arm trainer and 8.6 +/- 3.5 (13.6 +/- 7.9) for the electrical stimulation group. No patient could transport a block initially, but at completion significantly more arm trainer patients were able to transport at least three blocks (five vs. zero, P = 0.023). No significant differences were observed between the groups on the secondary Box and Block outcome at follow-up (eight vs. four patients). All Box and Block responders had an initial Fugl-Meyer assessment > or =10. Arm trainer training did not lead to a superior primary outcome over electrical stimulation training. However, "good performers" on the secondary outcome seemed to benefit more from the arm trainer training.

  1. Single-Photon Optomechanics

    Science.gov (United States)

    Nunnenkamp, A.; Børkje, K.; Girvin, S. M.

    2011-08-01

    Optomechanics experiments are rapidly approaching the regime where the radiation pressure of a single photon displaces the mechanical oscillator by more than its zero-point uncertainty. We show that in this limit the power spectrum has multiple sidebands and that the cavity response has several resonances in the resolved-sideband limit. Using master-equation simulations, we also study the crossover from the weak-coupling many-photon to the single-photon strong-coupling regime. Finally, we find non-Gaussian steady states of the mechanical oscillator when multiphoton transitions are resonant. Our study provides the tools to detect and take advantage of this novel regime of optomechanics.

  2. Uso de motores monofásicos acoplados mecanicamente em série, em irrigação por pivô central Utilization of mechanically coupled single phase motors in series in central pivot irrigation system

    Directory of Open Access Journals (Sweden)

    Delly Oliveira Filho

    2005-03-01

    Full Text Available A utilização de sistemas de irrigação por pivô central requer elevada potência elétrica, o que, em geral, implica em alto investimento inicial. No Brasil, a maioria das fazendas é eletrificada no sistema monofásico, devido ao fato de sua implantação requerer cerca de 40% do investimento inicial exigido pelo sistema trifásico. Salienta-se que a maior potência disponível no mercado de motores monofásicos no Brasil é de 9,2 kW (12,5 cv. Para suprir demanda de potência acima desta com sistema monofásico, propõe-se acoplar os motores monofásicos mecanicamente em série. Este trabalho teve como objetivo estimar o rendimento de um sistema de acoplamento e sua viabilidade técnico-econômica, comparado-o com outras formas de fornecimento de energia, diesel e sistema elétrico trifásico.The utilization of central pivot irrigation system requires in most cases high electric power which imply in high initial investment. Most of the Brazilian farms are electrified in the single phase electrical system, due to the fact that their implementation requires only about 40% of the initial investment as compared to three phase system. In Brazilian market the highest available power of single phase motors is 9.2 kW (12.5 hp. To supply power demand above this limit with single phase system one could couple mechanically the single phase motors in series. The objective of this work was to estimate the efficiency of such coupling system and to evaluate the economic and technical feasibility compared with other forms of energy supply such as diesel and three phase electrical system.

  3. Low-energy cross-section calculations of single molecules by electron impact: a classical Monte Carlo transport approach with quantum mechanical description

    Science.gov (United States)

    Madsen, J. R.; Akabani, G.

    2014-05-01

    The present state of modeling radio-induced effects at the cellular level does not account for the microscopic inhomogeneity of the nucleus from the non-aqueous contents (i.e. proteins, DNA) by approximating the entire cellular nucleus as a homogenous medium of water. Charged particle track-structure calculations utilizing this approximation are therefore neglecting to account for approximately 30% of the molecular variation within the nucleus. To truly understand what happens when biological matter is irradiated, charged particle track-structure calculations need detailed knowledge of the secondary electron cascade, resulting from interactions with not only the primary biological component—water--but also the non-aqueous contents, down to very low energies. This paper presents our work on a generic approach for calculating low-energy interaction cross-sections between incident charged particles and individual molecules. The purpose of our work is to develop a self-consistent computational method for predicting molecule-specific interaction cross-sections, such as the component molecules of DNA and proteins (i.e. nucleotides and amino acids), in the very low-energy regime. These results would then be applied in a track-structure code and thereby reduce the homogenous water approximation. The present methodology—inspired by seeking a combination of the accuracy of quantum mechanics and the scalability, robustness, and flexibility of Monte Carlo methods—begins with the calculation of a solution to the many-body Schrödinger equation and proceeds to use Monte Carlo methods to calculate the perturbations in the internal electron field to determine the interaction processes, such as ionization and excitation. As a test of our model, the approach is applied to a water molecule in the same method as it would be applied to a nucleotide or amino acid and compared with the low-energy cross-sections from the GEANT4-DNA physics package of the Geant4 simulation toolkit

  4. Correlation between cross-bridge kinetics obtained from Trp fluorescence of myofibril suspensions and mechanical studies of single muscle fibers in rabbit psoas.

    Science.gov (United States)

    Candau, Robin; Kawai, Masataka

    2011-12-01

    Our goal is to correlate kinetic constants obtained from fluorescence studies of myofibril suspension with those from mechanical studies of skinned muscle fibers from rabbit psoas. In myofibril studies, the stopped-flow technique with tryptophan fluorescence was used; in muscle fiber studies, tension transients with small amplitude sinusoidal length perturbations were used. All experiments were performed using the equivalent solution conditions (200 mM ionic strength, pH 7.00) at 10°C. The concentration of MgATP was varied to characterize kinetic constants of the ATP binding step 1 (K (1): dissociation constant), the binding induced cross-bridge detachment step 2 (k (2), k (-2): rate constants), and the ATP cleavage step 3 (k (3), k (-3)). In myofibrils we found that K (1) = 0.52 ± 0.08 mM (±95% confidence limits), k (2) = 242 ± 24 s(-1), and k (-2) ≈ 0; in muscle fibers, K (1) = 0.46 ± 0.06 mM, k (2) = 286 ± 32 s(-1), and k (-2) = 57 ± 21 s(-1). From these results, we conclude that myofibrils and muscle fibers exhibit nearly equal ATP binding step, and nearly equal ATP binding induced cross-bridge detachment step. Consequently, there is a good correlation between process C (phase 2 of step analysis) and the cross-bridge detachment step. The reverse detachment step is finite in fibers, but almost absent in myofibrils. We further studied partially cross-linked myofibrils and found little change in steps 2 and 3, indicating that cross-linking does not affect these steps. However, we found that K (1) is 2.5× of native myofibrils, indicating that MgATP binding is weakened by the presence of the extra load. We further studied the phosphate (Pi) effect in myofibrils, and found that Pi is a competitive inhibitor of MgATP, with the inhibitory dissociation constant of ~9 mM. Similar results were also deduced from fiber studies. To characterize the ATP cleavage step in myofibrils, we measured the slow rate constant in fluorescence, and

  5. Radioactive Substances Act 1960

    International Nuclear Information System (INIS)

    1960-01-01

    This Act regulates the keeping and use of radioactive material and makes provision for the disposal and storage of radioactive waste in the United Kingdom. It provides for a licensing system for such activities and for exemptions therefrom, in particular as concerns the United Kingdom Atomic Energy Authority. The Act repeals Section 4(5) of the Atomic Energy Authority Act, 1954 which made temporary provision for discharge of waste on or from premises occupied by the Authority. (NEA) [fr

  6. Learning dialog act processing

    OpenAIRE

    Wermter, Stefan; Löchel, Matthias

    1996-01-01

    In this paper we describe a new approach for learning dialog act processing. In this approach we integrate a symbolic semantic segmentation parser with a learning dialog act network. In order to support the unforeseeable errors and variations of spoken language we have concentrated on robust data-driven learning. This approach already compares favorably with the statistical average plausibility method, produces a segmentation and dialog act assignment for all utterances in a robust manner,...

  7. Radiological Protection Act 1970

    International Nuclear Information System (INIS)

    1970-01-01

    This Act provides for the establishment of a Radiological Protection Board to undertake research and advise on protection from radiation hazards. Its functions include provision of advice to Government departments with responsibilities in relation to protection of sectors of the community or the community as a whole against the hazards of ionizing radiation. The Act, which lays down that the Board shall replace certain departments concerned with radiation protection, repeals several Sections of the Radioactive Substances Act 1948 and the Science and Technology Act 1965. (NEA) [fr

  8. Adaptive mechanically controlled lubrication mechanism found in articular joints

    Science.gov (United States)

    Greene, George W.; Banquy, Xavier; Lee, Dong Woog; Lowrey, Daniel D.; Yu, Jing; Israelachvili, Jacob N.

    2011-01-01

    Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attributed to a single mechanism acting alone but on the synergistic action of multiple “modes” of lubrication that are adapted to provide optimum lubrication as the normal loads, shear stresses, and rates change. Hyaluronic acid (HA) is abundant in cartilage and synovial fluid and widely thought to play a principal role in joint lubrication although this role remains unclear. HA is also known to complex readily with the glycoprotein lubricin (LUB) to form a cross-linked network that has also been shown to be critical to the wear prevention mechanism of joints. Friction experiments on porcine cartilage using the surface forces apparatus, and enzymatic digestion, reveal an “adaptive” role for an HA-LUB complex whereby, under compression, nominally free HA diffusing out of the cartilage becomes mechanically, i.e., physically, trapped at the interface by the increasingly constricted collagen pore network. The mechanically trapped HA-LUB complex now acts as an effective (chemically bound) “boundary lubricant”—reducing the friction force slightly but, more importantly, eliminating wear damage to the rubbing/shearing surfaces. This paper focuses on the contribution of HA in cartilage lubrication; however, the system as a whole requires both HA and LUB to function optimally under all conditions. PMID:21383143

  9. Adaptive mechanically controlled lubrication mechanism found in articular joints.

    Science.gov (United States)

    Greene, George W; Banquy, Xavier; Lee, Dong Woog; Lowrey, Daniel D; Yu, Jing; Israelachvili, Jacob N

    2011-03-29

    Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attributed to a single mechanism acting alone but on the synergistic action of multiple "modes" of lubrication that are adapted to provide optimum lubrication as the normal loads, shear stresses, and rates change. Hyaluronic acid (HA) is abundant in cartilage and synovial fluid and widely thought to play a principal role in joint lubrication although this role remains unclear. HA is also known to complex readily with the glycoprotein lubricin (LUB) to form a cross-linked network that has also been shown to be critical to the wear prevention mechanism of joints. Friction experiments on porcine cartilage using the surface forces apparatus, and enzymatic digestion, reveal an "adaptive" role for an HA-LUB complex whereby, under compression, nominally free HA diffusing out of the cartilage becomes mechanically, i.e., physically, trapped at the interface by the increasingly constricted collagen pore network. The mechanically trapped HA-LUB complex now acts as an effective (chemically bound) "boundary lubricant"--reducing the friction force slightly but, more importantly, eliminating wear damage to the rubbing/shearing surfaces. This paper focuses on the contribution of HA in cartilage lubrication; however, the system as a whole requires both HA and LUB to function optimally under all conditions.

  10. Act II of the Sunshine Act.

    Science.gov (United States)

    Pham-Kanter, Genevieve

    2014-11-01

    To coincide with the introduction in the United States of the Sunshine Act, Genevieve Pham-Kanter discusses what we need to look for to fight hidden bias and deliberate or unconscious corruption. Please see later in the article for the Editors' Summary.

  11. Act II of the Sunshine Act.

    Directory of Open Access Journals (Sweden)

    Genevieve Pham-Kanter

    2014-11-01

    Full Text Available To coincide with the introduction in the United States of the Sunshine Act, Genevieve Pham-Kanter discusses what we need to look for to fight hidden bias and deliberate or unconscious corruption. Please see later in the article for the Editors' Summary.

  12. 25 CFR 700.33 - Act (The Act).

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false Act (The Act). 700.33 Section 700.33 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.33 Act (The Act). (a) The Act. The Act is Pub. L. 93-531, (88 Stat...

  13. Assessment of the adsorption mechanism of Flutamide anticancer drug on the functionalized single-walled carbon nanotube surface as a drug delivery vehicle: An alternative theoretical approach based on DFT and MD

    Science.gov (United States)

    Kamel, Maedeh; Raissi, Heidar; Morsali, Ali; Shahabi, Mahnaz

    2018-03-01

    In the present work, we have studied the drug delivery performance of the functionalized (5, 5) single-walled carbon nanotube with a carboxylic acid group for Flutamide anticancer drug in the gas phase as well as water solution by means of density functional theory calculations. The obtained results confirmed the energetic stability of the optimized geometries and revealed that the nature of drug adsorption on the functionalized carbon nanotube is physical. Our computations showed that the hydrogen bonding between active sites of Flutamide molecule and the carboxyl functional group of the nanotube plays a vital role in the stabilization of the considered configurations. The natural bond orbital analysis suggested that the functionalized nanotube plays the role of an electron donor and Flutamide molecule acts as an electron acceptor at the investigated complexes. In addition, molecular dynamics simulation is also utilized to investigate the effect of functionalized carbon nanotube chirality on the dynamic process of drug molecule adsorption on the nanotube surface. Simulation results demonstrated that drug molecules are strongly adsorbed on the functionalized nanotube surface with (10,5) chirality, as reflected by the most negative van der Waals interaction energy and a high number of hydrogen bonds between the functionalized nanotube and drug molecules.

  14. A new microcavity design for single molecule detection

    International Nuclear Information System (INIS)

    Steiner, M.; Schleifenbaum, F.; Stupperich, C.; Failla, A.V.; Hartschuh, A.; Meixner, A.J.

    2006-01-01

    We present a new microcavity design which allows for efficient detection of single molecules by measuring the molecular fluorescence emission coupled into a resonant cavity mode. The Fabry-Perot-type microresonator consists of two silver mirrors separated by a thin polymer film doped with dye molecules in ultralow concenctration. By slightly tilting one of the mirrors different cavity lengths can be selected within the same sample. Locally, on a μm scale, the microcavity still acts as a planar Fabry-Perot resonator. Using scanning confocal fluorescence microscopy, single emitters on resonance with a single mode of the microresonator can be spatially addressed. Our microcavity is demonstrated to be well-suited for investigating the coupling mechanism between single quantum emitters and single modes of the electromagnetic field. The microcavity layout could be integrated in a lab-on-a-microchip design for ultrasensitive microfluidic analytics and can be considered as an important improvement for single photon sources based on single molecules operating at room temperature

  15. Current and future peripherally-acting antitussives.

    Science.gov (United States)

    Dicpinigaitis, Peter V

    2006-07-28

    Cough is among the most common complaints for which medical evaluation is sought. The clinical significance of this problem is evidenced by the enormous financial expenditure on prescription and non-prescription cough remedies worldwide. Centrally-acting antitussive agents, such as opiates, are often associated with undesirable or intolerable side effects, including sedation, nausea, and constipation. Therefore, safe and effective peripherally-acting antitussive agents are particularly desirable. Relatively few commercially-available products suppress cough through a peripheral mechanism of action. Recent research in the field of cough has resulted in the development of several new classes of compounds that may prove to be clinically useful peripherally-acting antitussives.

  16. THE CHILD JUSTICE ACT: PROCEDURAL SENTENCING ISSUES

    African Journals Online (AJOL)

    Stephan

    2012-08-08

    Aug 8, 2012 ... research visits, and the Max Planck Institute for Foreign and International Criminal Law,. Freiburg, Germany ... Whether or not a pre-sentence report should be obtained before a child offender is sentenced has ...... the Criminal Procedure Act. It is important to read the quoted part of section 85(1) as a single ...

  17. Electrochemical and Electron Paramagnetic Resonance Study of the Mechanism of Oxidation of Phenazine-di-N-oxide in the Presence of Isopropyl alcohol at Glassy Carbon and Single-Walled Carbon Nanotube Electrodes

    International Nuclear Information System (INIS)

    Kulakovskaya, S.I.; Kulikov, A.V.; Sviridova, L.N.; Stenina, E.V.

    2014-01-01

    Graphical abstract: - Highlights: • The mechanism of oxidation of phenazine-di-N-oxide in the presence of isopropyl alcohol was studied. • The results are explained in terms of the E 1 C 1 E 2 C 2 mechanism of the two-stage electrode process. • The total two-electron catalytic oxidation of i-PrOH in the complex with the phenazine-di-N-oxide radical cation was assumed to occur. - Abstract: The mechanism of oxidation of phenazine-di-N-oxide in the presence of isopropyl alcohol was studied by cyclic voltammetry at glassy carbon (GC) and single-walled carbon nanotubes (SWCNT) electrodes in 0.1 M LiClO 4 solutions in acetonitrile. The adsorption of phenazine-di-N-oxide at SWCNT electrode in 0.1 M LiClO 4 solution in acetonitrile was investigated by measurement of the dependence of the differential double layer capacitance of the electrode C on potential E. The effect of isopropyl alcohol on the shape of cyclic voltammograms (CVs) of phenazine-di-N-oxide and the intensity of Electron Paramagnetic Resonance (EPR) signal of its radical cation was investigated. The catalytic currents were recorded at the oxidation of phenazine-di-N-oxide at SWCNT and GC electrodes in the presence of isopropyl alcohol. The results were explained in terms of the E 1 C 1 E 2 C 2 mechanism of two-stage electrode process characterized by catalytic current recorded at the second electrode stage. The overall two-electron catalytic oxidation of isopropyl alcohol in complex with the phenazine-di-N-oxide radical cation was assumed to occur. It was shown that SWCNT electrodes can be used in the electrocatalytic oxidation of organic compounds in the presence of electrochemically generated phenazine-di-N-oxide radical cation

  18. Evolving microstructure, magnetic properties and phase transition in a mechanically alloyed Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} single sample

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Ismayadi, E-mail: kayzen@gmail.com [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, Mansor; Kanagesan, Samikannu; Ibrahim, Idza Riati; Nazlan, Rodziah; Wan Ab Rahman, Wan Norailiana; Abdullah, Nor Hapishah; Mohd Idris, Fadzidah; Bahmanrokh, Ghazaleh; Shafie, Mohd Shamsul Ezzad [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Manap, Masni [Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2014-02-15

    We report on an investigation to unravel the dependence of magnetic properties on microstructure while they evolve in parallel under the influence of sintering temperature of a single sample of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} synthesized via mechanical alloying. A single sample, instead of the normally practiced approach of using multiple samples, was sintered at various sintering temperatures from 500 °C to 1400 °C. The morphology of the samples was studied by means of scanning electron microscopy (SEM) equipped with EDX; density measurement was conducted using the Archimedes principle; and hysteresis measurement was carried out using a B–H hysteresisgraph system. XRD data showed that the first appearance of a single phase was at 800 °C and an amorphous phase was traced at lower sintering temperatures. We correlated the microstructure and the magnetic properties and showed that the important grain-size threshold for the appearance of significant ordered magnetism (mainly ferromagnetism) was about ≥0.3 µm. We found that there were three stages of magnetic phase evolution produced via the sintering process with increasing temperatures. The first stage was dominated by paramagnetic states with some superparamagnetic behavior; the second stage was influenced by moderately ferromagnetic states and some paramagnetic states; and the third stage consisted of strongly ferromagnetic states with negligible paramagnetic states. We found that three factors sensitively influenced the sample's content of ordered magnetism—the ferrite-phase crystallinity degree, the number of grains above the critical grain size and the number of large enough grains for domain wall accommodation. - Highlights: • Grain-size threshold for starting-point appearance of ordered magnetism in single sample Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}. • The activation energies of grain growth were 16.10 kJ/mol and 137.65 kJ/mol. • Activation energy can be correlated to the first

  19. Nuclear Installations Act 1969

    International Nuclear Information System (INIS)

    1969-01-01

    The purpose of this Act is to amend the Nuclear Installations Act 1965 to bring it into full compliance with the international conventions on nuclear third party liability to which the United Kingdom is a Signatory, namely, the Paris Convention, the Brussels Supplementary Convention and the Vienna Convention. (NEA) [fr