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Sample records for hollow electron lens

  1. Hollow Electron Lens Simulation for the SPS

    CERN Document Server

    Previtali, V; Stancari, G; Valishev, A

    2013-01-01

    The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations

  2. Thermomechanical Assessment of the Collector for the Hollow Electron Lens

    CERN Document Server

    Anderson, George Bowers

    2017-01-01

    The hollow electron lens (HEL) is a system proposed for the High Luminosity upgrade of the Large Hadron Collider LHC (HL-LHC) [1]. Being considered for installation at LHC point 4, the HEL improves halo control and collimation of proton beams in the collider [2]. This is achieved by creating a hollow tube of electrons using an electron gun. This axisymmetric electron cloud travels around the proton beam for a few meters, overlapping with the proton beam halo, until the electron cloud is dissipated in a collector, which is the focus of this project. A 3D image of the HEL system is found in Figure 1 and a further technical description of such electron lenses is available in [3].

  3. Preliminary Design Study of the Hollow Electron Lens for LHC

    CERN Document Server

    Perini, Diego; CERN. Geneva. ATS Department

    2017-01-01

    A Hollow Electron Lens (HEL) has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field generated by a set of superconducting solenoids. The first step of the design is the definition of the magnetic fields that drive the electron trajectories. The estimation of such trajectories by means of a dedicated MATLAB® tool is presented. The influence of the main geometrical and electrical parameters are analysed and discussed. Then, the main mechanical design choices for the solenoids, cryostats gun and collector are described. The aim of this paper is to provide an overview of the preliminary design of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar ...

  4. Effect of pulsed hollow electron-lens operation on the proton beam core in LHC

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, Miriam [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Valishev, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-11-08

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the HL-LHC. In order to further increase the diffusion rates for a fast halo removal as e.g. desired before the squeeze, the electron lens (e-lens) can be operated in pulsed mode. In case of profile imperfections in the electron beam the pulsing of the e-lens induces noise on the proton beam which can, depending on the frequency content and strength, lead to emittance growth. In order to study the sensitivity to the pulsing pattern and the amplitude, a beam study (machine development MD) at the LHC has been proposed for August 2016 and we present in this note the preparatory simulations and estimates.

  5. Effect of pulsed hollow electron-lens operation on the proton beam core in LHC

    CERN Document Server

    Fitterer, Miriam; Valishev, Alexander

    2016-01-01

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the HL-LHC. In order to further increase the diffusion rates for a fast halo removal as e.g. desired before the squeeze, the electron lens (e-lens) can be operated in pulsed mode. In case of profile imperfections in the electron beam the pulsing of the e-lens induces noise on the proton beam which can, depending on the frequency content and strength, lead to emittance growth. In order to study the sensitivity to the pulsing pattern and the amplitude, a beam study (machine development MD) at the LHC has been proposed for August 2016 and we present in this note the preparatory simulations and estimates.

  6. Preliminary Mechanical Design Study of the Hollow Electron Lens for HL-LHC

    Energy Technology Data Exchange (ETDEWEB)

    Zanoni, Carlo [CERN; Gobbi, Giorgia [CERN; Perini, Diego [CERN; Stancari, Giulio [Fermilab

    2017-05-01

    A Hollow Electron Lens (HEL) has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a hollow beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field. The first step of the design is the definition of the magnetic field that drives the electron trajectories. The estimation of such trajectories by means of a dedicated MATLAB tool is presented. The influence of the main geometrical and electrical parameters is analyzed and discussed. Then, the main mechanical design choices for the solenoids, cryostats gun and collector are described. The aim of this paper is to provide an overview of the feasibility study of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar devices.

  7. Preliminary Mechanical Design Study of the Hollow Electron Lens for HL-LHC

    Science.gov (United States)

    Zanoni, Carlo; Gobbi, Giorgia; Perini, Diego; Stancari, Giulio

    2017-07-01

    A Hollow Electron Lens (HEL) has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a hollow beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field. The first step of the design is the definition of the magnetic field that drives the electron trajectories. The estimation of such trajectories by means of a dedicated MATLAB tool is presented. The influence of the main geometrical and electrical parameters is analyzed and discussed. Then, the main mechanical design choices for the solenoids, cryostats gun and collector are described. The aim of this paper is to provide an overview of the feasibility study of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar devices.

  8. Calculation of the transverse kicks generated by the bends of a hollow electron lens

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio

    2014-03-25

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam in high-energy accelerators. They were used in the Fermilab Tevatron collider for abort-gap clearing, beam-beam compensation, and halo scraping. A beam-beam compensation scheme based upon electron lenses is currently being implemented in the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. This work is in support of a conceptual design of hollow electron beam scraper for the Large Hadron Collider. It also applies to the implementation of nonlinear integrable optics with electron lenses in the Integrable Optics Test Accelerator at Fermilab. We consider the axial asymmetries of the electron beam caused by the bends that are used to inject electrons into the interaction region and to extract them. A distribution of electron macroparticles is deposited on a discrete grid enclosed in a conducting pipe. The electrostatic potential and electric fields are calculated using numerical Poisson solvers. The kicks experienced by the circulating beam are estimated by integrating the electric fields over straight trajectories. These kicks are also provided in the form of interpolated analytical symplectic maps for numerical tracking simulations, which are needed to estimate the effects of the electron lens imperfections on proton lifetimes, emittance growth, and dynamic aperture. We outline a general procedure to calculate the magnitude of the transverse proton kicks, which can then be generalized, if needed, to include further refinements such as the space-charge evolution of the electron beam, magnetic fields generated by the electron current, and longitudinal proton dynamics.

  9. Guide for 3D WARP simulations of hollow electron beam lenses. Practical explanation on basis of Tevatron electron lens test stand

    Energy Technology Data Exchange (ETDEWEB)

    Moens, Vince [Ecole Polytechnique Federale de Lausanne (EPFL) (Switzerland)

    2014-06-08

    The purpose of this guide is to help successive students handle WARP. It outlines the installation of WARP on personal computers as well as super-computers and clusters. It furthermore teaches the reader how to handle the WARP environment and run basic scripts. Lastly it outlines how to execute the current Hollow Electron Beam Lens scripts.

  10. Simulation study of Hollow Electron Beam Collimation in HL-LHC.

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Stancari, G. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Valishev, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Redaelli, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-10-05

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the HL-LHC. In this note we evaluate the performance of a hollow electron lens for different HL-LHC scenarios in terms of halo removal rates and the effect of profile imperfections of the electron beam on the proton beam core in case of a pulsed operation of the e-lens.

  11. Strength assessment of a cryostat used by the hollow electron test station.

    CERN Document Server

    Efremov, Filip

    2015-01-01

    The following report explains the work I have done on my summer student work project and the experience I have gained during the process. The work consisted of a strength assessment of a cryogenic vacuum insulated vessel according to European regulations. The cryogenic vacuum insulated vessel is used for the cooling of the solenoids. The solenoids are used in the hollow electron test station and create the magnetic fields used for testing electron guns and validating the concept of a hollow electron lens.

  12. HOLLOW ELECTRON BEAM COLLIMATION FOR HL-LHC - EFFECT ON THE BEAM CORE

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermilab; Stancari, G. [Fermilab; Valishev, A. [Fermilab; Bruce, R. [CERN; Papadopoulou, S. [CERN; Papotti, G. [CERN; Pellegrini, D. [CERN; Pellegrini, S. [CERN; Valuch, D. [CERN; Wagner, J. F. [CERN

    2016-10-05

    Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.

  13. Contact lens surface by electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jung Hyuck [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Suk Ju; Hwang, Kwang Ha; Jeon Jin [Dongshin Univ., Naju (Korea, Republic of)

    2011-07-01

    Contact lens materials needs good biocompatibility, high refractive index, high optical transparency, high water content etc. Surface treat method by using plasma and radiation can modify the physical and/or chemical properties of the contact lens surface. Radiation technology such as electron beam irradiation can apply to polymerization reaction and enhance the functionality of the polymer.The purpose of this study is to modify of contact lens surface by using Eb irradiation technology. Electron beam was irradiated to the contact lens surface which was synthesized thermal polymerization method and commercial contact lens to modify physical and chemical properties. Ft-IR, XP, UV-vis spectrophotometer, water content, oxygen trans-metastability were used to characterize the surface state, physicochemical, and optical property of the contact lens treated with Eb. The water content and oxygen transmissibility of the contact lens treated with Eb were increased due to increase in the hydrophilic group such as O-C=O and OH group on the contact lens surface which could be produced by possible reaction between carbon and oxygen during the Eb irradiation. All of the lenses showed the high optical transmittance above 90%. In this case of B/Es, TES, Ti contact lens, the optical transmittance decreased about 5% with increasing Eb dose in the wavelength of UV-B region. The contact lens modified by Eb irradiation could improve the physical properties of the contact lens such as water content and oxygen transmissibility.

  14. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G.; Kuznetsov, G.; Shiltsev, V.; Still, D.A.; Valishev, A.; Vorobiev, L.G.; Assmann, R.; Kabantsev, A.

    2010-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams

  15. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G; Kuznetsov, G; Shiltsev, V; Still, D A; Valishev, A; Vorobiev, L G; Assmann, R; Kabantsev, A

    2012-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.

  16. RHIC electron lens test bench diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Gassner, D.; Beebe, E.; Fischer, W.; Gu, X.; Hamdi, K.; Hock, J.; Liu, C.; Miller, T.; Pikin, A.; Thieberger, P.

    2011-05-16

    An Electron Lens (E-Lens) system will be installed in RHIC to increase luminosity by counteracting the head-on beam-beam interaction. The proton beam collisions at the RHIC experimental locations will introduce a tune spread due to a difference of tune shifts between small and large amplitude particles. A low energy electron beam will be used to improve luminosity and lifetime of the colliding beams by reducing the betatron tune shift and spread. In preparation for the Electron Lens installation next year, a test bench facility will be used to gain experience with many sub-systems. This paper will discuss the diagnostics related to measuring the electron beam parameters.

  17. Plans for Deployment of Hollow Electron Lenses at the LHC for Enhanced Beam Collimation

    Energy Technology Data Exchange (ETDEWEB)

    Redaelli, S. [CERN; Bertarelli, A. [CERN; Bruce, R. [CERN; Perini, D. [CERN; Rossi, A. [CERN; Salvachua, B. [CERN; Stancari, G. [Fermilab; Valishev, A. [Fermilab

    2015-06-01

    Hollow electron lenses are considered as a possible means to improve the LHC beam collimation system, providing active control of halo diffusion rates and suppressing the population of transverse halos. After a very successful experience at the Tevatron, a conceptual design of a hollow e-lens optimized for the LHC was produced. Recent further studies have led to a mature preliminary technical design. In this paper, possible scenarios for the deployment of this technology at the LHC are elaborated in the context of the scheduled LHC long shutdowns until the full implementation of the HL-LHC upgrade in 2023. Possible setups of electron beam test stands at CERN and synergies with other relevant electron beam programmes are also discussed.

  18. Pulser for the Tevatron electron lens gun

    Energy Technology Data Exchange (ETDEWEB)

    Iouri Terechkine et al.

    2004-05-18

    To compensate for beam-beam interaction in Tevatron, an ''electron lens'' is considered to be an effective instrument. When a bunch of electrons with energy in the range (10-16) kV is overlapping with a bunch of antiprotons, the resulting focusing force for antiprotons can be adjusted by changing the electron beam current and by profiling its radial distribution. There exist several scenarios of how the system must function. According to one of them, an electron gun that supplies electrons must be fed by voltage pulses that follow with the frequency of antiproton bunches circulating in the Tevatron, which is about 2.5 MHz. To provide focusing tailored for each individual antiproton bunch, a modulator of the gun (pulser) must allow pulse-to-pulse voltage change. This report will cover main approaches to a design of a pulser for use with the gun of the Tevatron Electron Lens.

  19. Simulations of Gaussian electron guns for RHIC electron lens

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-02-28

    Simulations of two versions of the electron gun for RHIC electron lens are presented. The electron guns have to generate an electron beam with Gaussian radial profile of the electron beam density. To achieve the Gaussian electron emission profile on the cathode we used a combination of the gun electrodes and shaping of the cathode surface. Dependence of electron gun performance parameters on the geometry of electrodes and the margins for electrodes positioning are presented.

  20. The correction of electron lens aberrations.

    Science.gov (United States)

    Hawkes, P W

    2015-09-01

    The progress of electron lens aberration correction from about 1990 onwards is chronicled. Reasonably complete lists of publications on this and related topics are appended. A present for Max Haider and Ondrej Krivanek in the year of their 65th birthdays. By a happy coincidence, this review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65. It is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction. They would both wish to associate their colleagues with such a tribute but it is the names of Haider and Krivanek (not forgetting Joachim Zach) that will remain in the annals of electron optics, next to that of Harald Rose. I am proud to know that both regard me as a friend as well as a colleague. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. An adjustable electron achromat for cathode lens microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-12-15

    Chromatic aberration correction in light optics began with the invention of a two-color-corrected achromatic crown/flint lens doublet by Chester Moore Hall in 1730. Such color correction is necessary because any single glass shows dispersion (i.e. its index of refraction changes with wavelength), which can be counteracted by combining different glasses with different dispersions. In cathode lens microscopes (such as Photo Electron Emission Microscopy – PEEM) we encounter a similar situation, where the chromatic aberration coefficient of the cathode lens shows strong dispersion, i.e. depends (non-linearly) on the energy with which the electrons leave the sample. Here I show how a cathode lens in combination with an electron mirror can be configured as an adjustable electron achromat. The lens/mirror combination can be corrected at two electron energies by balancing the settings of the electron mirror against the settings of the cathode lens. The achromat can be adjusted to deliver optimum performance, depending on the requirements of a specific experiment. Going beyond the achromat, an apochromat would improve resolution and transmission by a very significant margin. I discuss the requirements and outlook for such a system, which for now remains a wish waiting for fulfilment. - Highlights: • The properties of cathode objective lens plus electron mirror are discussed. • In analogy with light-optical achromats, cathode lens plus mirror can be configured as an electron achromat. • Unlike light optics, the electron achromat can be adjusted to best fulfill experimental requirements.

  2. The correction of electron lens aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hawkes, P.W., E-mail: peter.hawkes@cemes.fr

    2015-09-15

    The progress of electron lens aberration correction from about 1990 onwards is chronicled. Reasonably complete lists of publications on this and related topics are appended. A present for Max Haider and Ondrej Krivanek in the year of their 65th birthdays. By a happy coincidence, this review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65. It is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction. They would both wish to associate their colleagues with such a tribute but it is the names of Haider and Krivanek (not forgetting Joachim Zach) that will remain in the annals of electron optics, next to that of Harald Rose. I am proud to know that both regard me as a friend as well as a colleague. - Highlights: • Geometrical aberration correction. • Chromatic aberration correction. • 50 pm resolution. • High-resolution electron energy-loss spectroscopy. • Extensive bibliographies.

  3. Electron and ion kinetics in a micro hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G J; Iza, F; Lee, J K [Electronics and Electrical Engineering Department, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2006-10-21

    Electron and ion kinetics in a micro hollow cathode discharge are investigated by means of two-dimensional axisymmetric particle-in-cell Monte Carlo collision simulations. Argon discharges at 10 and 300 Torr are studied for various driving currents. Electron and ion energy probability functions (IEPF) are shown at various times and locations to study the spatio-temporal behaviour of the discharge. The electron energy probability function (EEPF) evolves from the Druyvesteyn type in the early stages of the discharge into a two (or three) temperature distribution when steady state is reached. In steady state, secondary electrons accelerated across the cathode fall populate the high energy tail of the EEPF while the low energy region is populated by trapped electrons. The IEPF evolves from a Maxwellian in the negative glow (bulk) to a two temperature distribution on the cathode surface. The overpopulation of low energy ions near the cathode surface is attributed to a larger collision cross section for low energy ions and ionization within the cathode fall.

  4. Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

    CERN Document Server

    Fitterer, M; Valishev, A; Bruce, R; Papotti, G; Redaelli, S; Valentino, G; Valentino, G; Valuch, D; Xu, C

    2017-01-01

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

  5. Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermilab; Stancari, G. [Fermilab; Valishev, A. [Fermilab; Bruce, R. [CERN; Papotti, G [CERN; Redaelli, S. [CERN; Valentino, G. [Malta U.; Valentino, G. [CERN; Valuch, D. [CERN; Xu, C. [CERN

    2017-06-13

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

  6. Polarization response of RHIC electron lens lattices

    Directory of Open Access Journals (Sweden)

    V. H. Ranjbar

    2016-10-01

    Full Text Available Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. In particular we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and threshold strengths of the spin resonances. These results are benchmarked and compared to two dimensional direct tracking results for the RHIC e-lens lattice and the standard lattice. Finally we consider the effect of longitudinal motion via chromatic scans using direct six dimensional lattice tracking.

  7. Observations and Measurements of Anomalous Hollow Electron Beams in a Storage Ring

    CERN Document Server

    Wu, Y K; Wu, Juhao

    2005-01-01

    This paper reports first observations and measurements of anomalous hollow electron beams in a storage ring. In a lattice with a negative chromaticity, hollow electron beams consisting of a solid core beam inside and a large ring beam outside have been created and studied in the Duke storage ring. We report the detailed measurements of the hollow beam phenomenon, including its distinct image pattern, spectrum signature, and its evolution with time. By capturing the post-instability bursting beam, the hollow beam is a unique model system for studying the transverse instabilities, in particular, the interplay of the wake field and the lattice nonlinearity. In addition, the hollow beam can be used as a powerful tool to study the linear and nonlinear particle dynamics in the storage ring.

  8. The electronic properties of superatom states of hollow molecules.

    Science.gov (United States)

    Feng, Min; Zhao, Jin; Huang, Tian; Zhu, Xiaoyang; Petek, Hrvoje

    2011-05-17

    Electronic and optical properties of molecules and molecular solids are traditionally considered from the perspective of the frontier orbitals and their intermolecular interactions. How molecules condense into crystalline solids, however, is mainly attributed to the long-range polarization interaction. In this Account, we show that long-range polarization also introduces a distinctive set of diffuse molecular electronic states, which in quantum structures or solids can combine into nearly-free-electron (NFE) bands. These NFE properties, which are usually associated with good metals, are vividly evident in sp(2) hybridized carbon materials, specifically graphene and its derivatives. The polarization interaction is primarily manifested in the screening of an external charge at a solid/vacuum interface. It is responsible for the universal image potential and the associated unoccupied image potential (IP) states, which are observed even at the He liquid/vacuum interface. The molecular electronic properties that we describe are derived from the IP states of graphene, which float above and below the molecular plane and undergo free motion parallel to it. Rolling or wrapping a graphene sheet into a nanotube or a fullerene transforms the IP states into diffuse atom-like orbitals that are bound primarily to hollow molecular cores, rather than the component atoms. Therefore, we named them the superatom molecular orbitals (SAMOs). Like the excitonic states of semiconductor nanostructures or the plasmonic resonances of metallic nanoparticles, SAMOs of fullerene molecules, separated by their van der Waals distance, can combine to form diatomic molecule-like orbitals of C(60) dimers. For larger aggregates, they form NFE bands of superatomic quantum structures and solids. The overlap of the diffuse SAMO wavefunctions in van der Waals solids provides a different paradigm for band formation than the valence or conduction bands formed by interaction of the more tightly bound

  9. Experimental and Numerical Studies on the Proposed Application of Hollow Electron Beam Collimation for the LHC at CERN

    Energy Technology Data Exchange (ETDEWEB)

    Moens, Vince [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-01-01

    This thesis work was carried out in the framework of the U.S. LHC Accelerator Research Program (USLARP), a collaboration between the European Organization for Nuclear Research (CERN) and the U.S. Department of Energy. The first half of the work was completed at Fermilab (USA), the location of the Tevatron, a proton-antiproton collider and the second largest particle collider in the world. The second half was completed at CERN (Switzerland), the location of the largest proton collider in the world (Large Hadron Collider (LHC)). This thesis characterizes a Hollow Electron Beam (HEB) for possible usage at the LHC to enhance its collimation through Hollow Electron Beam Lenses (HEBLs). Collimation is a long established principle in high energy particle accelerators. Hollow Electron Beam Collimation (HEBC) aims to enhance current collimation systems by controlling diffusion of primary halo particles into the limiting aperture. It works on the principle of a transverse radial electric field that kicks the primary halo particles outwards upon each pass in a multi-pass system. The transverse field is produced by a HEB that is coaxially aligned with the accelerator beam, producing a negligible electric field in the center and a strong transverse electric field at amplitudes higher than the inner radius of the electron beam. Ideally, halo particles are affected without perturbation of the beam core. One of the main advantages of this system is to decrease the dependence on instantaneous loss spikes and beam jitter. A solid experimental basis of HEBC was accumulated at the Tevatron. The application of this technique at the LHC is now under investigation. The aim of this thesis is to present a preliminary report to support a future optimal conceptual design report. It characterizes the available hardware in order to facilitate the design of a Hollow Electron Gun (HEG) for the LHC, characterizes the effect on beam diffusion by determining the transverse electric fields of the

  10. Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, I.A.; Stancari, G.; Valishev, A.; /Fermilab; Shatilov, D.N.; /Novosibirsk, IYF

    2012-05-01

    The concept of augmenting the conventional collimation system of high-energy storage rings with a hollow electron beam was successfully demonstrated in experiments at the Tevatron. A reliable numerical model is required for understanding particle dynamics in the presence of a hollow beam collimator. Several models were developed to describe imperfections of the electron beam profile and alignment. The features of the imperfections are estimated from electron beam profile measurements. Numerical simulations of halo removal rates are compared with experimental data taken at the Tevatron.

  11. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Previtali, Valentina [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Valishev, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bruce, Roderik [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Redaelli, Stefano [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Rossi, Adriana [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Salvachua Ferrando, Belen [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-06-26

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. We are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were checked to ensure that undesired effects were suppressed. Hardware specifications were based on the Tevatron devices and on preliminary engineering integration studies in the LHC machine. Required resources and a possible timeline were also outlined, together with a brief discussion of alternative halo-removal schemes and of other possible uses of electron lenses to improve the performance of the LHC.

  12. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    CERN Document Server

    Stancari, Giulio; Valishev, Alexander; Bruce, Roderik; Redaelli, Stefano; Rossi, Adriana; Salvachua Ferrando, Belen

    2014-01-01

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. Within the US LHC Accelerator Research Program (LARP) and the European FP7 HiLumi LHC Design Study, we are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were check...

  13. Anterior lens epithelium in cataract patients with retinitis pigmentosa - scanning and transmission electron microscopy study.

    Science.gov (United States)

    Andjelic, Sofija; Drašlar, Kazimir; Hvala, Anastazija; Hawlina, Marko

    2017-05-01

    In retinitis pigmentosa (RP) patients, relatively minor lens opacity in central part of posterior pole of the lens may cause disproportionate functional symptoms requiring cataract operation. To investigate the possible structural reasons for this opacity development, we studied the structure of the lens epithelium of patients with RP. The anterior lens capsule (aLC: basement membrane and associated lens epithelial cells, LECs) was obtained from cataract surgery and prepared for scanning and transmission electron microscopy (SEM and TEM). Both SEM and TEM show a number of abnormal features in the anterior lens epithelium of cataract patients with RP. The abnormalities appear mainly as holes, thinning and degradation of the epithelium, with the dimensions from cataractous lens. We suggest that the lens epithelium has a role in the development of the cataract in patients with RP. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  14. FEL indulators with the hollow-ring electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Epp, V.; Bordovitsyn, V. [Tomsk State Univ. (Russian Federation); Kozhevnikov, A. [Tomsk Pedagogical Institute (Russian Federation)] [and others

    1995-12-31

    A conceptual design of undulators with a modulated longitudinal magnetic field is proposed. The magnetic field is created by use of a solenoid with axis coincident with the electron beam axis. In order to modulate the magnetic field we propose an insertion of a row of alternating ferromagnetic and superconducting diaphragms in line with electron beam. The simulation of two-dimensional distribution of the magnetic field in the plane containing undulator axis was made using the computer code {open_quotes}Mermaid{close_quotes}. The magnetic field was analysed as a function of the system geometry. The dependence on the spacing l between superconducting diaphragms, inner a and outer b radii of the last ones is investigated. Two versions of the device are considered: with ferromagnetic rings made of magnetically soft material placed between the superconducting diaphragms and without them. It is shown that the field modulation depth increases with ratio of b/l and can exceed 50% in case of the ferromagnetic insertions. An approximate analytical calculation of the magnetic field distribution is performed as follows. The axial-symmetrical magnetic field can be defined by the vector potential with only one nonzero component A(r,{phi}) where r and {phi} are the cylindrical coordinates. The solution of the Laplace`s equation is found under the assumption that the magnetic field is infinitely extended and periodic along the z-axis. The boundary conditions are defined by the undulator design. The result is used for the calculation of the particle dynamics and for the investigations of the trajectory stability. The spectral and angular distribution of the radiation emitted from the described systems is found. The estimations show that the proposed design allows to create relatively high magnitude of the magnetic field (up to 1 T) with a short period about 1 cm or less.

  15. Electron Acceleration by Beating of Two Intense Cross-Focused Hollow Gaussian Laser Beams in Plasma

    Science.gov (United States)

    Mahmoud, Saleh T.; Gauniyal, Rakhi; Ahmad, Nafis; Rawat, Priyanka; Purohit, Gunjan

    2018-01-01

    This paper presents propagation of two cross-focused intense hollow Gaussian laser beams (HGBs) in collisionless plasma and its effect on the generation of electron plasma wave (EPW) and electron acceleration process, when relativistic and ponderomotive nonlinearities are simultaneously operative. Nonlinear differential equations have been set up for beamwidth of laser beams, power of generated EPW, and energy gain by electrons using WKB and paraxial approximations. Numerical simulations have been carried out to investigate the effect of typical laser-plasma parameters on the focusing of laser beams in plasmas and further its effect on power of excited EPW and acceleration of electrons. It is observed that focusing of two laser beams in plasma increases for higher order of hollow Gaussian beams, which significantly enhanced the power of generated EPW and energy gain. The amplitude of EPW and energy gain by electrons is found to enhance with an increase in the intensity of laser beams and plasma density. This study will be useful to plasma beat wave accelerator and in other applications requiring multiple laser beams. Supported by United Arab Emirates University for Financial under Grant No. UPAR (2014)-31S164

  16. Direct electron transfer and electrochemical study of hemoglobin immobilized in ZnO hollow spheres.

    Science.gov (United States)

    Liu, Changhua; Xu, Jing; Wu, Zongfang

    2011-10-01

    ZnO hollow spheres were firstly prepared. A new type of amperometric hydrogen peroxide biosensor was fabricated by entrapping Hemoglobin (Hb) through the ZnO hollow spheres (ZHS) nanoparticles. The composition morphology and size were studied by transmission electron microscopy. The surface topography of the prepared films was imaged by atomic force microscope (AFM). Several techniques, including UV-vis absorption spectroscopy, cyclic voltammetry, chronoamperometry were employed to characterize the performance of the biosensor. The results indicated that the ZHS nanoparticles had enhanced the performance of the hydrogen peroxide sensors. The electrochemical parameters of Hb in the ZHS were calculated by the results of the electron-transfer coefficient (α) and the apparent heterogeneous electron-transfer rate constant K (s) as 0.5 and 3.1 s(-1), respectively. The resulting biosensors showed a wide linear range from 2.1 × 10(-6) to 5.18 × 10(-3) M, with a low detection limit of 7.0 × 10(-7) M (S/N = 3) under optimized experimental conditions. The results demonstrated that the ZHS matrix may improve the protein loading with the retention of bioactivity and greatly promote the direct electron transfer, which can be attributed to its unique morphology, high specific surface area, and biocompatibility. The biosensor obtained from this study possesses high sensitivity, good reproducibility, and long-term stability.

  17. Corrections of magnification and focusing in a cathode lens-equipped scanning electron microscope.

    Science.gov (United States)

    Zobacová, J; Zobac, M; Oral, M; Müllerová, I; Frank, L

    2006-01-01

    One of the well-proven and efficient methods of obtaining a very low-energy impact of primary electrons in the scanning electron microscope is to introduce a retarding field element below the pole piece of the objective lens (OL). It is advantageous to use the specimen alone as the negatively biased electrode (i.e., cathode of the cathode lens). The optical power of the cathode lens modifies some of the standard parameters of the image formation such as relation of working distance to OL excitation or magnification to the scanning coils current, the impact angle of primary electrons, and so forth. In computer-controlled electron microscopes these parameters, particularly with regard to focusing and magnification, can be corrected automatically. Derivation of algorithms for such corrections and their experimental verifications are presented in this paper. Furthermore, a more accurate analytical expression for the focal length of an aperture lens is derived.

  18. Axicon Lens for Electrons Using a Magnetic Vortex: The Efficient Generation of a Bessel Beam

    Science.gov (United States)

    Zheng, Changlin; Petersen, Timothy C.; Kirmse, Holm; Neumann, Wolfgang; Morgan, Michael J.; Etheridge, Joanne

    2017-10-01

    We demonstrate experimentally an efficient electron axicon lens using a magnetic vortex. We show that naturally occurring magnetic vortices with circular magnetic moment distributions in a soft-magnetic thin film create conical phase shifts for fast electrons. Such radially symmetric linear phase ramps are equivalent to ideal light optical axicons. We apply this lens to generate efficient nondiffracting electron Bessel beams, which we observe experimentally in through-focus Lorentz images as well as in propagated off-axis electron holograms. This highlights the potential for using magnetic nanostructures as highly efficient and flexible phase plates for crafting desired electron beam shapes.

  19. Control of the diocotron instability of a hollow electron beam with periodic dipole magnets

    Science.gov (United States)

    Jo, Y. H.; Kim, J. S.; Stancari, G.; Chung, M.; Lee, H. J.

    2018-01-01

    A method to control the diocotron instability of a hollow electron beam with periodic dipole magnetic fields has been investigated by a two-dimensional particle-in-cell simulation. At first, relations between the diocotron instability and several physical parameters such as the electron number density, the current and shape of the electron beam, and the solenoidal field strength are theoretically analyzed without periodic dipole magnetic fields. Then, we study the effects of the periodic dipole magnetic fields on the diocotron instability using the two-dimensional particle-in-cell simulation. In the simulation, we considered the periodic dipole magnetic field applied along the propagation direction of the beam, as a temporally varying magnetic field in the beam frame. A stabilizing effect is observed when the oscillating frequency of the dipole magnetic field is optimally chosen, which increases with the increasing amplitude of the dipole magnetic field.

  20. Electron Lens Construction for the Integrable Optics Test Accelerator at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    McGee, Mike [Fermilab; Carlson, Kermit [Fermilab; Nobrega, Lucy [Fermilab; Stancari, Giulio [Fermilab; Valishev, Alexander [Fermilab

    2016-06-01

    The Integrable Optics Test Accelerator (IOTA) is proposed for operation at Fermilab. The goal of IOTA is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. The IOTA is a 40 m circumference, 150 MeV (e-), 2.5 MeV (p⁺) diagnostic test ring. Construction of an electron lens for IOTA is necessary for both electron and proton operation. Components required for the Electron Lens design include; a 0.8 T conventional water-cooled main solenoid, and magnetic bending and focusing elements. The foundation of the design relies on repurposing the Fermilab Tevatron Electron Lens II (TELII) gun and collector under ultra-high vacuum (UHV) conditions.

  1. High-quality electron beam generation in a proton-driven hollow plasma wakefield accelerator

    Science.gov (United States)

    Li, Y.; Xia, G.; Lotov, K. V.; Sosedkin, A. P.; Hanahoe, K.; Mete-Apsimon, O.

    2017-10-01

    Simulations of proton-driven plasma wakefield accelerators have demonstrated substantially higher accelerating gradients compared to conventional accelerators and the viability of accelerating electrons to the energy frontier in a single plasma stage. However, due to the strong intrinsic transverse fields varying both radially and in time, the witness beam quality is still far from suitable for practical application in future colliders. Here we demonstrate the efficient acceleration of electrons in proton-driven wakefields in a hollow plasma channel. In this regime, the witness bunch is positioned in the region with a strong accelerating field, free from plasma electrons and ions. We show that the electron beam carrying the charge of about 10% of 1 TeV proton driver charge can be accelerated to 0.6 TeV with a preserved normalized emittance in a single channel of 700 m. This high-quality and high-charge beam may pave the way for the development of future plasma-based energy frontier colliders.

  2. Demonstration of electron beam focusing by a laser-plasma lens

    CERN Document Server

    Thaury, Cédric; Döpp, Andreas; Lehe, Remi; Lifschitz, Agustin; Phuoc, Kim Ta; Gautier, Julien; Goddet, Jean-Philippe; Tafzi, Amar; Flacco, Alessandro; Tissandier, Fabien; Sebban, Stéphane; Rousse, Antoine; Malka, Victor

    2014-01-01

    Laser-plasma technology promises a drastic reduction of the size of high energy electron accelerators. It could make free electron lasers available to a broad scientific community, and push further the limits of electron accelerators for high energy physics. Furthermore the unique femtosecond nature of the source makes it a promising tool for the study of ultra-fast phenomena. However, applications are hindered by the lack of suitable lens to transport this kind of high-current electron beams, mainly due to their divergence. Here we show that this issue can be solved by using a laser-plasma lens, in which the field gradients are five order of magnitude larger than in conventional optics. We demonstrate a reduction of the divergence by nearly a factor of three, which should allow for an efficient coupling of the beam with a conventional beam transport line.

  3. The objective lens of the electron microscope with correction of spherical and axial chromatic aberrations.

    Science.gov (United States)

    Bimurzaev, S B; Aldiyarov, N U; Yakushev, E M

    2017-10-01

    The paper describes the principle of operation of a relatively simple aberration corrector for the transmission electron microscope objective lens. The electron-optical system of the aberration corrector consists of the two main elements: an electrostatic mirror with rotational symmetry and a magnetic deflector formed by the round-shaped magnetic poles. The corrector operation is demonstrated by calculations on the example of correction of basic aberrations of the well-known objective lens with a bell-shaped distribution of the axial magnetic field. Two of the simplest versions of the corrector are considered: a corrector with a two-electrode electrostatic mirror and a corrector with a three-electrode electrostatic mirror. It is shown that using the two-electrode mirror one can eliminate either spherical or chromatic aberration of the objective lens, without changing the value of its linear magnification. Using a three-electrode mirror, it is possible to eliminate spherical and chromatic aberrations of the objective lens simultaneously, which is especially important in designing electron microscopes with extremely high resolution. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Medical Application of Free Electron Laser Trasmittance using Hollow Optical Fiber

    CERN Document Server

    Suzuki, Sachiko; Ishii, Katsonuri

    2004-01-01

    Mid-infrared Free Electron Laser (FEL) is expected as new application for biomedical surgery. However, delivery of MIR-FEL into the body is difficult because the common glass optical fibers have strong absorption at MIR region. A good operational and flexible line for FEL is required at medical field. A Hollow optical fiber is developed for IR laser and high-power laser delivery. We evaluated the fiber for FEL transmission line. This fiber is coated with cyclic olefin polymer (COP) and silver thin film on the inside of glass capillary tube. It is 700 μm-bore and 1m in lengths. The fiber transmission loss of the measured wavelength region of 5.5 μm to 12 μm is less than 1dB/m when the fiber is straight and 1.2 dB/m when bent to radius of 20 cm. Additionally, the output beam profile and the pulse structure is not so different form incidence beam. In conclusion, the fiber is suitable for delivery of the FEL energy for applications in medical and laser surgery.

  5. Stretchable Electronic Platform for Soft and Smart Contact Lens Applications

    OpenAIRE

    Vasquez Quintero, Andrés Felipe; Verplancke, Rik; De Smet, Herbert; Vanfleteren, Jan

    2017-01-01

    A stretchable platform with spherical-shaped electronics based on thermo- plastic polyurethane (TPU) is introduced for soft smart contact lenses. The low glass transition temperature of TPU, its relatively low hardness, and its proven biocompatibility (i.e., protection of exterior body wounds) fulfill the essential requirements for eye wearable devices. These requirements include optical transparency, conformal fitting, and flexibility comparable with soft contact lense...

  6. Beam Dynamics in an Electron Lens with the Warp Particle-in-cell Code

    CERN Document Server

    Stancari, Giulio; Redaelli, Stefano

    2014-01-01

    Electron lenses are a mature technique for beam manipulation in colliders and storage rings. In an electron lens, a pulsed, magnetically confined electron beam with a given current-density profile interacts with the circulating beam to obtain the desired effect. Electron lenses were used in the Fermilab Tevatron collider for beam-beam compensation, for abort-gap clearing, and for halo scraping. They will be used in RHIC at BNL for head-on beam-beam compensation, and their application to the Large Hadron Collider for halo control is under development. At Fermilab, electron lenses will be implemented as lattice elements for nonlinear integrable optics. The design of electron lenses requires tools to calculate the kicks and wakefields experienced by the circulating beam. We use the Warp particle-in-cell code to study generation, transport, and evolution of the electron beam. For the first time, a fully 3-dimensional code is used for this purpose.

  7. A magnetized Einzel lens electron dump for the Linac4 H− ion source

    CERN Document Server

    Midttun, O; Kronberger, M; Lettry, J; Pereira, H; Scrivens, R

    2013-01-01

    Linac4 is a 160 MeV linear accelerator which will inject negative hydrogen ions (H−) into CERN’s Proton Synchrotron Booster, a required upgrade to improve the beam brightness in the LHC injector chain. A volume production RF ion source, based on the design of the DESY RF source was implemented, but showed considerable electron dump ablation during operation at 45 keV beam energy. To reduce the electron beam power density in the dump, a magnetized Einzel lens is designed that reduces the beam energy to 10 keV before permanentmagnets dump the electrons on a tungsten surface. Presented in this paper are simulations of the design using IBSimu, the tunable range of parameters depending on the extracted H− and electron current, as well as details of the implementation, the choice of pulsed power converters and the electrode alignment system. In addition, simulations of proton extraction from this source will be shown.

  8. eV-TEM: Transmission electron microscopy in a low energy cathode lens instrument

    Energy Technology Data Exchange (ETDEWEB)

    Geelen, Daniël, E-mail: geelen@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Thete, Aniket [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Schaff, Oliver; Kaiser, Alexander [SPECS GmbH, Voltastrasse 5, D-13355 Berlin (Germany); Molen, Sense Jan van der [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Tromp, Rudolf [IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, NY 10598 (United States)

    2015-12-15

    We are developing a transmission electron microscope that operates at extremely low electron energies, 0–40 eV. We call this technique eV-TEM. Its feasibility is based on the fact that at very low electron energies the number of energy loss pathways decreases. Hence, the electron inelastic mean free path increases dramatically. eV-TEM will enable us to study elastic and inelastic interactions of electrons with thin samples. With the recent development of aberration correction in cathode lens instruments, a spatial resolution of a few nm appears within range, even for these very low electron energies. Such resolution will be highly relevant to study biological samples such as proteins and cell membranes. The low electron energies minimize adverse effects due to radiation damage. - Highlights: • We present a new way of performing low energy transmission electron microscopy in an aberration corrected LEEM/PEEM instrument. • We show a proof of principle where we measure transmitted electrons through a suspended graphene monolayer with a preliminary setup. • We present an improved setup design that provides better control of the incident electron beam.

  9. HIGH-CURRENT COLD CATHODE FIELD EMISSION ARRAY FOR ELECTRON LENS APPLICATION

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L

    2012-12-28

    During Phase I, the following goals were achieved: (1) design and fabrication of a novel, nano-dimensional CNT field emitter assembly for high current density application, with high durability; (2) fabrication of a ceramic based micro channel plate (MCP) and characterization of its secondary electron emission; and (3) characterizing the CNT/MCP cathode for high field emission and durability. As a result of these achievements, a relatively high current density of ~ 1.2 A/cm2 from a CNT cathode and single channel MCP were measured. The emission current was also extremely stable with a peak-to-peak variation of only 1.8%. The emission current could be further enhanced to meet requirements for electron lens applications by increasing the number of MCP channels. A calculation for maximum possible current density with a 1200 channel/cm2 MCP, placed over a cathode with 1200 uniformly functioning CNTs, would be ~1.46 kA/cm2, neglecting space charge limitations. Clearly this level of emission is far greater than what is needed for the electron lens application, but it does offer a highly comforting margin to account for sub-standard emitters and/or to allow the lesser challenge of building a cathode with fewer channels/cm2. A satisfactory goal for the electron lens application would be a controllable emission of 2-4 mA per channel in an ensemble of 800-1200 uniformly-functioning channels/cm2, and a cathode with overall area of about 1 cm2.

  10. The electron lens test bench for the relativistic heavy ion collider at Brookhaven National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X., E-mail: xgu@bnl.gov; Altinbas, F.Z.; Beebe, E.; Fischer, W.; Frak, B.M.; Gassner, D.M.; Hamdi, K.; Hock, J.; Hoff, L.; Kankiya, P.; Lambiase, R.; Luo, Y.; Mapes, M.; Mi, J.; Miller, T.; Montag, C.; Nemesure, S.; Okamura, M.; Olsen, R.H.; Pikin, A.I.; and others

    2014-04-11

    To compensate for the beam–beam effects from the proton–proton interactions at the two interaction points IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC), we are constructing two electron lenses (e-lenses) that we plan to install in the interaction region IR10. Before installing them, the electron gun, collector, instrumentation were tested and the electron beam properties were qualified on an electron lens test bench. We will present the test results and discuss our measurement of the electron beam current and of the electron gun perveance. We achieved a maximum current of 1 A with 5 kV energy for both the pulsed- and the DC-beam (which is a long turn-by-turn pulse beam). We measured beam transverse profiles with an yttrium aluminum garnet (YAG) screen and pinhole detector, and compared those to simulated beam profiles. Measurements of the pulsed electron beam stability were obtained by measuring the modulator voltage.

  11. Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, P; Vaz, P [Technological and Nuclear Institute, Estrada Nacional No 10, 2686-953 Sacavem (Portugal); Zankl, M; Schlattl, H, E-mail: pedro.nogueira@helmholtz-muenchen.de [Helmholtz Zentrum Muenchen-German Research Center for Environmental Health, Research Unit Medical Radiation Physics and Diagnostics, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

    2011-11-07

    The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

  12. [Corneal epithelial changes of soft contact lens wearers under a transmission electron microscope].

    Science.gov (United States)

    Gu, Hao; Tang, Li

    2015-03-01

    To investigate the difference in corneal epithelium between patients with and without soft contact lens (SCL) wearing, and to analyze corneal epithelial changes of the eyes with long-time SCL wearing. In this cross sectional study, the subjects were divided into two groups: 13 patients of daily SCL wearers and 11 control subjects who had never worn contact lenses. The flap of corneal epithelium was observed by transmission electron microscopy. The corneal epithelial microvillus density was compared between the two groups. Transmission electron micrographs of the control group showed a tight connection between cells, regularly aligned basal cells, and continuous basement membrane. Compared with the control group, SCL wearers showed incomplete basement membrane, swollen epithelial cells, swollen mitochondria, and widened intercellular interstices. The density of corneal epithelium microvilli [(0.071466 +/- 0.015889)/microm2 vs. (0.139851 +/- 0.024171)/micro2] was lower (t = 8.312, P < 0.05). Long-term SCL wearing can induce remarkable changes of corneal epithelial tissue, and the density of corneal epithelial microvilli decreases.

  13. SU-E-T-556: Monte Carlo Generated Dose Distributions for Orbital Irradiation Using a Single Anterior-Posterior Electron Beam and a Hanging Lens Shield

    Energy Technology Data Exchange (ETDEWEB)

    Duwel, D [Cincinnati, OH (United States); Lamba, M; Elson, H; Kumar, N [University of Cincinnati, Cincinnati, OH (United States)

    2015-06-15

    Purpose: Various cancers of the eye are successfully treated with radiotherapy utilizing one anterior-posterior (A/P) beam that encompasses the entire content of the orbit. In such cases, a hanging lens shield can be used to spare dose to the radiosensitive lens of the eye to prevent cataracts. Methods: This research focused on Monte Carlo characterization of dose distributions resulting from a single A-P field to the orbit with a hanging shield in place. Monte Carlo codes were developed which calculated dose distributions for various electron radiation energies, hanging lens shield radii, shield heights above the eye, and beam spoiler configurations. Film dosimetry was used to benchmark the coding to ensure it was calculating relative dose accurately. Results: The Monte Carlo dose calculations indicated that lateral and depth dose profiles are insensitive to changes in shield height and electron beam energy. Dose deposition was sensitive to shield radius and beam spoiler composition and height above the eye. Conclusion: The use of a single A/P electron beam to treat cancers of the eye while maintaining adequate lens sparing is feasible. Shield radius should be customized to have the same radius as the patient’s lens. A beam spoiler should be used if it is desired to substantially dose the eye tissues lying posterior to the lens in the shadow of the lens shield. The compromise between lens sparing and dose to diseased tissues surrounding the lens can be modulated by varying the beam spoiler thickness, spoiler material composition, and spoiler height above the eye. The sparing ratio is a metric that can be used to evaluate the compromise between lens sparing and dose to surrounding tissues. The higher the ratio, the more dose received by the tissues immediately posterior to the lens relative to the dose received by the lens.

  14. A hollow cathode ion source for production of primary ions for the BNL electron beam ion source

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, James, E-mail: alessi@bnl.gov; Beebe, Edward; Carlson, Charles; McCafferty, Daniel; Pikin, Alexander; Ritter, John [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2014-02-15

    A hollow cathode ion source, based on one developed at Saclay, has been modified significantly and used for several years to produce all primary 1+ ions injected into the Relativistic Heavy Ion Collider Electron Beam Ion Source (EBIS) at Brookhaven. Currents of tens to hundreds of microamperes have been produced for 1+ ions of He, C, O, Ne, Si, Ar, Ti, Fe, Cu, Kr, Xe, Ta, Au, and U. The source is very simple, relying on a glow discharge using a noble gas, between anode and a solid cathode containing the desired species. Ions of both the working gas and ionized sputtered cathode material are extracted, and then the desired species is selected using an ExB filter before being transported into the EBIS trap for charge breeding. The source operates pulsed with long life and excellent stability for most species. Reliable ignition of the discharge at low gas pressure is facilitated by the use of capacitive coupling from a simple toy plasma globe. The source design, and operating experience for the various species, is presented.

  15. The physical and chemical properties of polymerization reaction for contact lens irradiated by electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Sin, Junghyeok; Jun, Jin [Dongshin Univ., Naju (Korea, Republic of)

    2010-07-01

    Can EB irradiation be possible the polymerization of HEMA without the cross-linker and initiator? The physical and chemical properties of the polymers are compared between the two polymerization methods Discuss the effects of the EB irradiation on the polymerization for having a good physical properties for the both hard and soft contact lens. EB irradiation can be used to the polymerization reaction and the EB polymerization take place at a very short period of time without any cross-linker and initiator and initiator above 100 kGy of EB dose. The polymer synthesized by EB irradiation can improve the physical properties of contact lens {yields} increase of the OH group on the surface by EB irradiation, resulting in increase o the water content and oxygen permeability of the contact lens The contact lens synthesized by EB irradiation could improve the physical properties of the contact lens, and specially can apply to a disposable soft contact lens with high water content and oxygen permeability.

  16. Hollow Core?

    Science.gov (United States)

    Qiao, G. J.; Liu, J. F.; Wang, Yang; Wu, X. J.; Han, J. L.

    We carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could be $\\beta<0.5^\\circ$. The ``hollow core'' is in agreement with Inverse Compton Scattering model of radio pulsars.

  17. Fast Focal Point Correction in Prism-Coupled Total Internal Reflection Scanning Imager Using an Electronically Tunable Lens

    Directory of Open Access Journals (Sweden)

    Chenggang Zhu

    2018-02-01

    Full Text Available Total internal reflection (TIR is useful for interrogating physical and chemical processes that occur at the interface between two transparent media. Yet prism-coupled TIR imaging microscopes suffer from limited sensing areas due to the fact that the interface (the object plane is not perpendicular to the optical axis of the microscope. In this paper, we show that an electrically tunable lens can be used to rapidly and reproducibly correct the focal length of an oblique-incidence scanning microscope (OI-RD in a prism-coupled TIR geometry. We demonstrate the performance of such a correction by acquiring an image of a protein microarray over a scan area of 4 cm2 with an effective resolution of less than 20 microns. The electronic focal length tuning eliminates the mechanical movement of the illumination lens in the scanning microscope and in turn the noise and background drift associated with the motion.

  18. Grain size determination in nano-scale polycrystalline aggregates by precession illumination-hollow cone dark field imaging in the transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Kulovits, A.K., E-mail: akk8@pitt.edu; Facco, G.; Wiezorek, J.M.K.

    2012-01-15

    Precession illumination hollow cone dark field (PI-HCDF) transmission electron microscopy (TEM) provides high contrast multi-beam dark field images, which are suitable for effective and robust grain size measurements in nano-scale polycrystalline aggregates. Precession illumination with slightly converged electron beam probes and precession angles up to 3 Degree-Sign has been produced using a computer-controlled system using a JEOL JEM 2000FX TEM instrument. Theoretical and practical aspects of the experimental technique are discussed using example precession illumination hollow cone diffraction patterns from single crystalline NiAl and the importance of selecting the appropriate precession angle for PI-HCDF image formation and interpretation is described. Results obtained for precession illumination are compared with those of conventional parallel beam illumination experiments. Nanocrystalline Al has been used to evaluate the influence of the precession angle on PI-HCDF image contrast with a focus on grain size analysis. PI-HCDF imaging has been applied for grain size measurements in regions of a nanocrystalline Al thin film adjacent to the edge of a pulsed laser melted and rapidly solidified region and determined the dimensions of a heat-affected zone. - Highlights: Black-Right-Pointing-Pointer New TEM method for grain size measurements combines TEM resolution with obtainability of statistically significant data sets. Black-Right-Pointing-Pointer We use precession illumination to produce time precession illumination hollow cone diffraction patterns PI-HCDP. Black-Right-Pointing-Pointer Contrast in dark field images (PI-HCDF) formed from PI-HCDP is easy to interpret as dynamical effects are reduced. Black-Right-Pointing-Pointer PI-HCDFs use several time-averaged g-rings simultaneously and contain more information than conventional DF-images. Black-Right-Pointing-Pointer Easy contrast interpretation and less dark field images required, allows fast, robust and

  19. A new practical model of an objective lens with assembling clearance for transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Li Wenping, E-mail: liwp@buaa.edu.c [Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Gui Lijiang; Wu Jian; Dong Quanlin; Yao Junen [Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China)

    2011-03-01

    A new objective lens model including magnetic pole pieces, coil windings, magnetic circuit as well as the assembling clearance between the pole piece and magnetic circuit is developed to obtain high simulation precision. The calculation is based on the second-order finite element method (SOFEM) with the measured B-H magnetization curves of the lens materials. The magnetic pole pieces and magnetic circuit are firstly optimized to reduce the lens saturation and obtain minimum spherical aberration coefficient, then modified to release the magnetic flux leakage caused by the increased clearance. In the end, an example is given for a 200 kV TEM with the point resolution of 0.25 nm and off-axis aberration coefficients at the image plane are calculated for dynamic correction. Results show that the magnetic circuit is unsaturated and the saturated area is only 0.8x4.8 mm{sup 2} around the lower pole piece with a maximum magnetic flux density of 2.537 T. This model can reduce the magnetic flux leakage and obtain the point resolution with smaller excitation. The calculation also shows that the off-axis aberrations require correcting dynamically to acquire fine image quality under low system magnification.

  20. Growth of hollow cell spheroids in microbead templated chambers.

    Science.gov (United States)

    Wang, Eddie; Wang, Dong; Geng, Andrew; Seo, Richard; Gong, Xiaohua

    2017-10-01

    Cells form hollow, spheroidal structures during the development of many tissues, including the ocular lens, inner ear, and many glands. Therefore, techniques for in vitro formation of hollow spheroids are valued for studying developmental and disease processes. Current in vitro methods require cells to self-organize into hollow morphologies; we explored an alternative strategy based on cell growth in predefined, spherical scaffolds. Our method uses sacrificial, gelatin microbeads to simultaneously template spherical chambers within a hydrogel and deliver cells into the chambers. We use mouse lens epithelial cells to demonstrate that cells can populate the internal surfaces of the chambers within a week to create numerous hollow spheroids. The platform supports manipulation of matrix mechanics, curvature, and biochemical composition to mimic in vivo microenvironments. It also provides a starting point for engineering organoids of tissues that develop from hollow spheroids. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Effect of energy band gap in graphene on negative refraction through the veselago lens and electron conductance

    Science.gov (United States)

    Dahal, Dipendra; Gumbs, Godfrey

    2017-01-01

    A remarkable property of intrinsic graphene is that upon doping, electrons and holes travel through the monolayer thick material with constant velocity which does not depend on energy up to about 0.3 eV (Dirac fermions), as though the electrons and holes are massless particles and antiparticles which move at the Fermi velocity vF. Consequently, there is Klein tunneling at a p-n junction, in which there is no backscattering at normal incidence of massless Dirac fermions. However, this process yielding perfect transmission at normal incidence is expected to be affected when the group velocity of the charge carriers is energy dependent and there is non-zero effective mass for the target particle. We investigate how away from normal incidence the combined effect of incident electron energy ɛ and band gap parameter Δ can determine whether a p-n junction would allow focusing of an electron beam by behaving like a Veselago lens with negative refractive index. We demonstrate that there is a specific region in ɛ - Δ space where the index of refraction is negative, i.e., where monolayer graphene behaves as a metamaterial. Outside this region, the refractive index may be positive or there may be no refraction at all. We compute the ballistic conductance across a p-n junction as a function of Δ and ɛ and compare our results with those for a single electrostatic potential barrier and multiple barriers.

  2. Field calculations, single-particle tracking, and beam dynamics with space charge in the electron lens for the Fermilab Integrable Optics Test Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Noll, Daniel [Goethe Univ., Frankfurt (Germany); Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-11-17

    An electron lens is planned for the Fermilab Integrable Optics Test Accelerator as a nonlinear element for integrable dynamics, as an electron cooler, and as an electron trap to study space-charge compensation in rings. We present the main design principles and constraints for nonlinear integrable optics. A magnetic configuration of the solenoids and of the toroidal section is laid out. Singleparticle tracking is used to optimize the electron path. Electron beam dynamics at high intensity is calculated with a particle-in-cell code to estimate current limits, profile distortions, and the effects on the circulating beam. In the conclusions, we summarize the main findings and list directions for further work.

  3. Design and performance of a 30 KV electron gun with ten independent cathodes & a magnetic lens.

    Energy Technology Data Exchange (ETDEWEB)

    Rudys, Joseph Matthew; Reed, Kim Warren

    2006-08-01

    Measurements on a 30 kV electron gun with ten independent cathodes, operating in a 6.5 Tesla (T) magnetic field are presented. An earlier paper covered the design of this electron gun [1]. Experimental results are compared to model predictions. Beam current is compared to theoretical space charge limited flow.

  4. Spatial Control of Photoemitted Electron Beams using a Micro-Lens-Array Transverse-Shaping Technique

    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, A. [Northern Illinois U.; Qiang, G. [Tsinghua U., Beijing, Dept. Eng. Phys.; Ha, G. [POSTECH; Wisniewski, E. [Argonne (main); Piot, P. [NIU, DeKalb; Power, J. G. [Argonne (main); Gai, W. [Argonne (main)

    2017-07-24

    A common issue encountered in photoemission electron sources used in electron accelerators is the transverse inhomogeneity of the laser distribution resulting from the laser-amplification process and often use of frequency up conversion in nonlinear crystals. A inhomogeneous laser distribution on the photocathode produces charged beams with lower beam quality. In this paper, we explore the possible use of microlens arrays (fly-eye light condensers) to dramatically improve the transverse uniformity of the drive laser pulse on UV photocathodes. We also demonstrate the use of such microlens arrays to generate transversely-modulated electron beams and present a possible application to diagnose the properties of a magnetized beam.

  5. Direct observation of iron-induced conformational changes of mitochondrial DNA by high-resolution field-emission in-lens scanning electron microscopy.

    OpenAIRE

    Yaffee, M; Walter, P; Richter, C; Müller, M

    1996-01-01

    When respiring rat liver mitochondria are incubated in the presence of Fe(III) gluconate, their DNA (mtDNA) relaxes from the supercoiled to the open circular form dependent on the iron dose. Anaerobiosis or antioxidants fail to completely inhibit the unwinding. High-resolution field-emission in-lens scanning electron microscopy imaging, in concert with backscattered electron detection, pinpoints nanometer-range iron colloids bound to mtDNA isolated from iron-exposed mitochondria. High-resolut...

  6. The Electrospun Ceramic Hollow Nanofibers

    Directory of Open Access Journals (Sweden)

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  7. Hollow MEMS

    DEFF Research Database (Denmark)

    Larsen, Peter Emil

    a hollow MEMS sensor has been designed, fabricated and tested. Combined density, viscosity, buoyant mass spectrometry and IR absorption spectroscopy are possible on liquid samples and micron sized suspended particles (e.g. single cells). Measurements are based on changes in the resonant behavior...... of these sensors. Optimization of the microfabrication process has led to a process yield of almost 100% .This is achieved despite the fact, that the process still offers a high degree of flexibility. By simple modifications the Sensor shape can be optimized for different size ranges and sensitivities...... technologies and pre-concentration approaches. A thorough theoretical analysis of the expected sensor responsivity and sensitivity is performed. Predictions made are confirmed by finite element simulations. Using these tools the sensor geometry is optimized for ideal performance in both mass density and IR...

  8. Quadrupole lens alignment with improved STIM and secondary electron imaging for Proton Beam Writing

    Science.gov (United States)

    Qureshi, Sarfraz; Raman, P. Santhana; Stegmaier, Alrik; van Kan, Jeroen A.

    2017-08-01

    Minimal proximity effect coupled with uniform energy deposition in thin polymer layers make Proton Beam Writing (PBW) an intuitive direct-write lithographic technique. Feature sizes matching the focused beam spot size have been fabricated in photoresists down to 19 nm. Reproducible sub-10 nm beam focusing will make PBW a promising contender for sub-10 nm lithography. In this paper, we present beam size characterization by imaging a PBW resolution standard using transmitted/scattered ions and secondary electrons. Using Scanning Transmission Ion Microscopy (STIM) spectra for 1 and 2 MeV H2+ beams, we experimentally measure the thickness of the resolution standard to be 0.9 ± 0.1 μm, applying two independent calibration methods, which match the original intended thickness during fabrication. Through bias optimization of a Micro-Channel Plate (MCP), we show a tuneable secondary electron detection per proton for imaging with a maximum of 75% e/p for a beam of 1 MeV H2+. Based on STIM mode beam size measurement, we discuss considerations for quadrupole system alignment in order to remove higher order translational and rotational misalignments critical to achieve sub-40 nm spot sizes. A spot size of 13 × 32 nm2 (STIM) was achieved using a newly developed interface, capable of autofocusing ion beams and performing PBW.

  9. Engineers' Responsibilities for Global Electronic Waste: Exploring Engineering Student Writing Through a Care Ethics Lens.

    Science.gov (United States)

    Campbell, Ryan C; Wilson, Denise

    2017-04-01

    This paper provides an empirically informed perspective on the notion of responsibility using an ethical framework that has received little attention in the engineering-related literature to date: ethics of care. In this work, we ground conceptual explorations of engineering responsibility in empirical findings from engineering student's writing on the human health and environmental impacts of "backyard" electronic waste recycling/disposal. Our findings, from a purposefully diverse sample of engineering students in an introductory electrical engineering course, indicate that most of these engineers of tomorrow associated engineers with responsibility for the electronic waste (e-waste) problem in some way. However, a number of responses suggested attempts to deflect responsibility away from engineers towards, for example, the government or the companies for whom engineers work. Still other students associated both engineers and non-engineers with responsibility, demonstrating the distributed/collective nature of responsibility that will be required to achieve a solution to the global problem of excessive e-waste. Building upon one element of a framework for care ethics adopted from the wider literature, these empirical findings are used to facilitate a preliminary, conceptual exploration of care-ethical responsibility within the context of engineering and e-waste recycling/disposal. The objective of this exploration is to provide a first step toward understanding how care-ethical responsibility applies to engineering. We also hope to seed dialogue within the engineering community about its ethical responsibilities on the issue. We conclude the paper with a discussion of its implications for engineering education and engineering ethics that suggests changes for educational policy and the practice of engineering.

  10. Switching a Nanocluster Core from Hollow to Non-hollow

    KAUST Repository

    Bootharaju, Megalamane Siddaramappa

    2016-03-24

    Modulating the structure-property relationship in atomically precise nanoclusters (NCs) is vital for developing novel NC materials and advancing their applications. While promising biphasic ligand-exchange (LE) strategies have been developed primarily to attain novel NCs, understanding the mechanistic aspects involved in tuning the core and the ligand-shell of NCs in such biphasic processes is challenging. Here, we design a single phase LE process that enabled us to elucidate the mechanism of how a hollow NC (e.g., [Ag44(SR)30]4-, -SR: thiolate) converts into a non-hollow NC (e.g., [Ag25(SR)18]-), and vice versa. Our study reveals that the complete LE of the hollow [Ag44(SPhF)30]4- NCs (–SPhF: 4-fluorobenzenethiolate) with incoming 2,4-dimethylbenzenethiol (HSPhMe2) induced distortions in the Ag44 structure forming the non-hollow [Ag25(SPhMe2)18]- by a disproportionation mechanism. While the reverse reaction of [Ag25(SPhMe2)18]- with HSPhF prompted an unusual dimerization of Ag25, followed by a rearrangement step that reproduces the original [Ag44(SPhF)30]4-. Remarkably, both the forward and the backward reactions proceed through similar size intermediates that seem to be governed by the boundary conditions set by the thermodynamic and electronic stability of the hollow and non-hollow metal cores. Furthermore, the resizing of NCs highlights the surprisingly long-range effect of the ligands which are felt by atoms far deep in the metal core, thus opening a new path for controlling the structural evolution of nanoparticles.

  11. Distinguishing thermal lens effect from electronic third-order nonlinear self-phase modulation in liquid suspensions of 2D nanomaterials.

    Science.gov (United States)

    Wang, Yanan; Tang, Yingjie; Cheng, Peihong; Zhou, Xufeng; Zhu, Zhuan; Liu, Zhaoping; Liu, Dong; Wang, Zhiming; Bao, Jiming

    2017-03-09

    The interaction of light with atomically thin nanomaterials has attracted enormous research interest in order to understand two-dimensional (2D) electron systems and develop novel opto-electronic devices. The observations of spatial self-phase modulation and the associated multiple diffraction ring patterns in liquid suspensions of 2D nanomaterials are believed to be excellent examples of strong laser interaction with 2D nanomaterials and this phenomenon has been attributed to their large electronic third-order susceptibilities. By performing a series of control experiments with liquid suspensions of graphene and graphene oxide flakes in different solvents at various temperatures under an increasing modulation frequency of laser illumination, we first show that the diffraction ring pattern has little dependence on the type of nanomaterial but strongly depends on the duration of laser illumination. A laser induced local refractive index change is then monitored by a weaker probe beam, resulting in the divergent diffraction of the probe beam that indicates a lower self-induced refractive index in the center of the pump laser beam than at its periphery: a clear signature of the thermal lens effect. Finally, we use computational fluid dynamics to simulate laser induced temperature and index changes of the suspensions. The evolution of diffraction rings is well correlated to the transient temperature distribution. Our understanding of complex laser interactions with nanomaterial suspensions and the associated thermal lens effect paves the way for further basic studies and fluid opto-electronic applications of 2D nanomaterials.

  12. Metamaterial Lens of Specifiable Frequency-Dependent Focus and Adjustable Aperture for Electron Cyclotron Emission in the DIII-D Tokamak

    Science.gov (United States)

    Hammond, K. C.; Massidda, S. D.; Capecchi, W. J.; Volpe, F. A.

    2013-08-01

    Electron Cyclotron Emission (ECE) of different frequencies originates at different locations in non-uniformly magnetized plasmas. For simultaneous observation of multiple ECE frequencies from the outside edge of a toroidal plasma confinement device (e.g. a tokamak), the focal length of the collecting optics should increase with the frequency to maximize the resolution on a line of sight along the magnetic field gradient. Here we present the design and numerical study of a zoned metamaterial lens with such characteristics, for possible deployment with the 83-130 GHz ECE radiometer in the DIII-D tokamak. The lens consists of a concentric array of miniaturized element phase-shifters. These were reverse-engineered starting from the desired Gaussian beam waist locations and further optimized to account for diffraction and finite-aperture effects that tend to displace the waist. At the same time we imposed high and uniform transmittance, averaged over all phase-shifters. The focal length is shown to increase from 1.32 m to 2.08 m over the frequency range of interest, as desired for low-field DIII-D discharges (B = -1.57 T). Retracting the lens to receded positions rigidly moves the waists accordingly, resulting in a good match—within a fraction of the Rayleigh length—of the EC-emitting layer positions at higher fields (up to B= -2.00 T). Further, it is shown how varying the lens aperture might move the waists "non-rigidly" to better match the non-rigid movement of the EC-emitting layers with the magnetic field. The numerical method presented is very general and can be used to engineer any dependence of the focal length on the frequency, including zero or minimal chromatic aberration.

  13. Hollow Prosthetic Eyes.

    Science.gov (United States)

    Worrell, Emma

    A new technique to produce hollow prostheses is presented. A small case series of patients utilized standard methods to fabricate hollow ocular prostheses where rehabilitation had proved difficult. This article describes the fabrication and results of hollow ocular prostheses. Each hollow eye was significantly reduced in weight, one-third lighter than the original weight, with the exact size, shape, and volume of the existing solid prosthesis. This simple design significantly reduced the weight of these eyes and revolutionized these patients' rehabilitation. Previously the solid prostheses overburdened the lower eyelids, causing discomfort, irritation, discharge, and reddening, whereas the new lightweight prostheses are unobtrusive, comfortable, and good aesthetically.

  14. Computational predictions of zinc oxide hollow structures

    Science.gov (United States)

    Tuoc, Vu Ngoc; Huan, Tran Doan; Thao, Nguyen Thi

    2018-03-01

    Nanoporous materials are emerging as potential candidates for a wide range of technological applications in environment, electronic, and optoelectronics, to name just a few. Within this active research area, experimental works are predominant while theoretical/computational prediction and study of these materials face some intrinsic challenges, one of them is how to predict porous structures. We propose a computationally and technically feasible approach for predicting zinc oxide structures with hollows at the nano scale. The designed zinc oxide hollow structures are studied with computations using the density functional tight binding and conventional density functional theory methods, revealing a variety of promising mechanical and electronic properties, which can potentially find future realistic applications.

  15. [Hollow foot in adults].

    Science.gov (United States)

    Braun, S

    1997-01-01

    Contrary to the general impression, the hollow foot is much more common than the flat foot. We distinguish three categories of hollow foot: varus hollow (clinical form I), valgus hollow (clinical form II), and pseudo-hollow (clinical form III). These three clinical forms have a common deviation dynamics, the consequence of shortening of the sural-Achilles-calcaneoplantar system. Metatarsalgia often precedes deformation of the front of the foot. Talalgia is linked to excess traction or to a conflict between the heel and the back of the shoe. Common therapy consists of plantar orthoses, eventually toe orthoses and orthopedic shoes. When surgery is used in the adult, it is generally not to correct excess cavus but to correct problems of the front of the foot such as hallux valgus, involvement of the second metatarsal bone (??), or toenails.

  16. Sunglass Lens

    Science.gov (United States)

    1984-01-01

    Foster Grant's Space Technology Lens, manufactured under license from NASA, combines NASA technology with Foster Grant's own technology. The NASA contribution was a highly abrasion-resistant coating developed at Ames Research Center as a means of protecting plastic surfaces of aerospace equipment from the sometimes harsh environments to which they are subjected. The Space Tech Lens, now manufactured by Fosta-Tek, surpasses glass in abrasion resistant properties and has five times better scratch resistance than the most popular corrective lenses.

  17. Lens Model

    DEFF Research Database (Denmark)

    Nash, Ulrik William

    2014-01-01

    Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory of probabil......Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory...... of probabilistic functionalism, and concerns the environment and the mind, and adaptation by the latter to the former. This entry is about the lens model, and probabilistic functionalism more broadly. Focus will mostly be on firms and their employees, but, to fully appreciate the scope, we have to keep in mind...

  18. Application of modified hollow fiber liquid phase microextraction in conjunction with chromatography-electron capture detection for quantification of acrylamide in waste water samples at ultra-trace levels.

    Science.gov (United States)

    Sobhi, Hamid Reza; Ghambarian, Mahnaz; Behbahani, Mohammad; Esrafili, Ali

    2017-03-03

    Herein, a simple and sensitive method was successfully developed for the extraction and quantification of acrylamide in water samples. Initially, acrylamide was derivatized through a bromination process. Subsequently, a modified hollow-fiber liquid-phase microextraction was applied for the extraction of the brominated acrylamide from a 10-ml portion of an aqueous sample. Briefly, in this method, the derivatized acrylamide (2,3-dibromopropionamide) was extracted from the aqueous sample into a thin layer of an organic solvent sustained in pores of a porous hollow fiber. Then, it was back-extracted using a small volume of organic acceptor solution (acetonitril, 25μl) located inside the lumen of the hollow fiber followed by gas chromatography-electron capture detection (GC-ECD). The optimal conditions were examined for the extraction of the analyte such as: the organic solvent: dihexyl ether+10% tri-n-octyl phosphine oxide; stirring rate: 750rpm; no salt addition and 30min extraction time. These optimal extraction conditions allowed excellent enrichment factor values for the method. Enrichment factor, detection limit (S/N=3) and dynamic linear range of 60, 2ngL-1 and 50-1000ngL-1 to be determined for the analyte. The relative standard deviations (RSD%) representing precision of the method were in the range of 2.2-5.8 based on the average of three measurements. Accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 93 to 108%. Finally, the method proved to be simple, rapid, and cost-effective for routine screen of acrylamide-contaminated highly-complicated untreated waste water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Determination of the solid angle and response function of a hemispherical spectrograph with injection lens for Auger electrons emitted from long lived projectile states.

    Science.gov (United States)

    Doukas, S; Madesis, I; Dimitriou, A; Laoutaris, A; Zouros, T J M; Benis, E P

    2015-04-01

    We present SIMION 8.1 Monte Carlo type simulations of the response function and detection solid angle for long lived Auger states (lifetime τ ∼ 10(-9) - 10(-5) s) recorded by a hemispherical spectrograph with injection lens and position sensitive detector used for high resolution Auger spectroscopy of ion beams. Also included in these simulations for the first time are kinematic effects particular to Auger emission from fast moving projectile ions such as line broadening and solid angle limitations allowing for a more accurate and realistic line shape modeling. Our results are found to be in excellent agreement with measured electron line shapes of both long lived 1s2s2p(4)P and prompt Auger projectile states formed by electron capture in collisions of 25.3 MeV F(7+) with H2 and 12.0 MeV C(4+) with Ne recorded at 0° to the beam direction. These results are important for the accurate evaluation of the 1s2s2p (4)P/(2)P ratio of K-Auger cross sections whose observed non-statistical production by electron capture into He-like ions, recently a field of interesting interpretations, awaits further resolution.

  20. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  1. How do Colluvial Hollows Fill?

    Science.gov (United States)

    Hales, T. C.; Parker, R.; Mudd, S. M.; Grieve, S. W. D.

    2016-12-01

    In humid, soil-mantled mountains shallow landslides commonly initiate in colluvial hollows, areas where convergent topography can lead to high pore pressures during storms. Immediately post-landslide initiation, a thin veneer of colluvial material accumulates by small-scale slumping from landslide headscarps. Thereafter colluvium accumulates in hollows primarily through creep-dominated processes like tree throw and animal burrowing, recording the hillslope sediment flux since the last landslide event. We measured the post-landslide hillslope sediment flux in 30 colluvial hollows in the southern Appalachians using radiocarbon measurements collected from soil pits excavated at the centre of steep, landslide-prone hollows. We collected material from the soil-saprolite/bedrock boundary at each location for radiocarbon dating and dated different chemical fractions of the soil (humic acid, humin, charcoal) in an attempt to bracket the "true" age of the soil. We calculated infilling rates of each hollow by measuring soil depths in cross-hollow transects and dividing this by the age of the hollow. The interquartile range of hollow basal ages is 2278-8184 cal. yrs B.P., demonstrating the long return period of landslides in most colluvial hollows. Hillslope erosion rates calculated assuming a linear diffusion transport law show that the transport coefficient (diffusivity) of the hollows varied by 4 orders of magnitude 10-5 to 10-1 m2 yr-1, despite the hollows being formed in regionally consistent geology and vegetation. Uncertainty in the dating and hollow geometry measurements can, at most, account for an order of magnitude of that variability. Our results show that hollows have a phase of rapid infilling that slows through time, consistent with previous observations. Despite this, the oldest hollows show several orders of magnitude variation in the transport coefficient, suggesting local, hollow scale variations in process significantly affect hillslope erosion rates.

  2. Electronic Portfolio Adoption: Developing a Framework by Exploring Faculty Perspectives Through the Lens of Diffusion of Innovation Theory

    OpenAIRE

    Blevins, Samantha Jane

    2013-01-01

    The use of electronic portfolios (ePortfolios) to support learning, assessment, and professional development across higher education has increased in recent years. However, higher education faculty who are instrumental to successful adoption and implementation are not often invited as active participants in the innovation process. In addition, while student perspectives of ePortfolio adoption are well represented in the literature, faculty perspectives are not. The goal of this research study...

  3. Hollow fiber liquid-liquid-liquid microextraction followed by solid-phase microextraction and in situ derivatization for the determination of chlorophenols by gas chromatography-electron capture detection.

    Science.gov (United States)

    Saraji, Mohammad; Ghani, Milad

    2015-10-30

    A method based on the combination of hollow fiber liquid-liquid-liquid microextraction and solid-phase microextraction (SPME) followed by gas chromatography-electron capture detection was developed for the determination of chlorophenols in water and wastewater samples. Silica microstructures fabricated on the surface of a stainless steel wire were coated by an organic solvent and used as a SPME fiber. The analytes were extracted through a hollow fiber membrane containing n-decane from sample solution to an alkaline aqueous acceptor phase. They were then extracted and in situ derivatized on the SPME fiber using acetic anhydride. Experimental parameters such as the type of extraction solvent, acceptor phase NaOH concentration, donor phase HCl concentration, the amount of derivatizing reagent, salt concentration, stirring rate and extraction time were investigated and optimized. The precision of the method for the analytes at 0.02-30μgL(-1) concentration level ranged from 7.1 to 10.2% (as intra-day relative standard deviation) and 6.4 to 9.8% (as inter-day relative standard deviation). The linear dynamic ranges were in the interval of 5-500μgL(-1), 0.05-5μgL(-1), 0.02-1μgL(-1) and 0.001-0.5μgL(-1) for 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, respectively. The enrichment factors were between 432 and 785. The limits of detection were in the range of 0.0004-1.2μgL(-1). Tap water, well water and wastewater samples were also analyzed to evaluate the method capability for real sample analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Evaluation of a new electronic preoperative reference marker for toric intraocular lens implantation by two different methods of analysis: Adobe Photoshop versus iTrace.

    Science.gov (United States)

    Farooqui, Javed Hussain; Sharma, Mansi; Koul, Archana; Dutta, Ranjan; Shroff, Noshir Minoo

    2017-01-01

    The aim of this study is to compare two different methods of analysis of preoperative reference marking for toric intraocular lens (IOL) after marking with an electronic marker. Cataract and IOL Implantation Service, Shroff Eye Centre, New Delhi, India. Fifty-two eyes of thirty patients planned for toric IOL implantation were included in the study. All patients had preoperative marking performed with an electronic preoperative two-step toric IOL reference marker (ASICO AE-2929). Reference marks were placed at 3-and 9-o'clock positions. Marks were analyzed with two systems. First, slit-lamp photographs taken and analyzed using Adobe Photoshop (version 7.0). Second, Tracey iTrace Visual Function Analyzer (version 5.1.1) was used for capturing corneal topograph examination and position of marks noted. Amount of alignment error was calculated. Mean absolute rotation error was 2.38 ± 1.78° by Photoshop and 2.87 ± 2.03° by iTrace which was not statistically significant (P = 0.215). Nearly 72.7% of eyes by Photoshop and 61.4% by iTrace had rotation error ≤3° (P = 0.359); and 90.9% of eyes by Photoshop and 81.8% by iTrace had rotation error ≤5° (P = 0.344). No significant difference in absolute amount of rotation between eyes when analyzed by either method. Difference in reference mark positions when analyzed by two systems suggests the presence of varying cyclotorsion at different points of time. Both analysis methods showed an approximately 3° of alignment error, which could contribute to 10% loss of astigmatic correction of toric IOL. This can be further compounded by intra-operative marking errors and final placement of IOL in the bag.

  5. Preparation and surface encapsulation of hollow TiO nanoparticles for electrophoretic displays

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Qian [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tan Tingfeng, E-mail: tantingfeng@sina.com [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Qi Peng [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Wang Shirong, E-mail: wangshirong@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Bian Shuguang [High Technology Research and Development Center, Ministry of Science and Technology, Beijing 100044 (China); Li Xianggao; An Yong; Liu Zhaojun [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2011-02-01

    Hollow black TiO nanosparticles were obtained via deposition of inorganic coating on the surface of hollow core-shell polymer latex with Ti(OBu){sub 4} as precursor and subsequent calcination in ammonia gas. Hollow TiO particles were characterized by scanning electron microscope, transmission electronic microscopy, X-ray diffraction, and thermogravimetric analysis. Encapsulation of TiO via dispersion polymerization was promoved by pretreating the pigments with 3-(trimethoxysilyl) propyl methacrylate, making it possible to prepare hollow TiO-polymer particles. When St and DVB were used as polymerization monomer, hollow TiO-polymer core-shell particles came into being via dispersion polymerization, and the lipophilic degree is 28.57%. Glutin-arabic gum microcapsules containing TiO-polymer particles electrophoretic liquid were prepared using via complex coacervation. It was founded that hollow TiO-polymer particles had enough electrophoretic mobility after coating with polymer.

  6. Preparation and surface encapsulation of hollow TiO nanoparticles for electrophoretic displays

    Science.gov (United States)

    Zhao, Qian; Tan, Tingfeng; Qi, Peng; Wang, Shirong; Bian, Shuguang; Li, Xianggao; An, Yong; Liu, Zhaojun

    2011-02-01

    Hollow black TiO nanosparticles were obtained via deposition of inorganic coating on the surface of hollow core-shell polymer latex with Ti(OBu)4 as precursor and subsequent calcination in ammonia gas. Hollow TiO particles were characterized by scanning electron microscope, transmission electronic microscopy, X-ray diffraction, and thermogravimetric analysis. Encapsulation of TiO via dispersion polymerization was promoved by pretreating the pigments with 3-(trimethoxysilyl) propyl methacrylate, making it possible to prepare hollow TiO-polymer particles. When St and DVB were used as polymerization monomer, hollow TiO-polymer core-shell particles came into being via dispersion polymerization, and the lipophilic degree is 28.57%. Glutin-arabic gum microcapsules containing TiO-polymer particles electrophoretic liquid were prepared using via complex coacervation. It was founded that hollow TiO-polymer particles had enough electrophoretic mobility after coating with polymer.

  7. Synthesis of barium-strontium titanate hollow tubes using Kirkendall effect

    Science.gov (United States)

    Chen, Xuncai; Im, SangHyuk; Kim, Jinsoo; Kim, Woo-Sik

    2018-02-01

    (BaSr)TiO3 hexagonal hollow tubes was fabricated by a solid-state interfacial reaction including a Kirkendall diffusion. Using a co-precipitation and sol-gel process, a core@shell structure of (BaSr)CO3@TiO2 rods were prepared, and then converted to (BaSr)TiO3 hollow tubes at 750 °C. This was a first achievement of single-phase crystal hollow tube. Here, the inner diameter and wall thickness of hollow tube were about 700 nm and 130 nm, respectively. The fabrication of (BaSr)TiO3 hollow tubes was monitored with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to investigate their formation mechanism. The present synthetic approach would provide a new insight into the design and fabrication of hollow architectures of many perovskite oxides.

  8. Hollow Microporous Organic Capsules

    Science.gov (United States)

    Li, Buyi; Yang, Xinjia; Xia, Lingling; Majeed, Muhammad Irfan; Tan, Bien

    2013-01-01

    Fabrication of hollow microporous organic capsules (HMOCs) could be very useful because of their hollow and porous morphology, which combines the advantages of both microporous organic polymers and non-porous nanocapsules. They can be used as storage materials or reaction chambers while supplying the necessary path for the design of controlled uptake/release systems. Herein, the synthesis of HMOCs with high surface area through facile emulsion polymerization and hypercrosslinking reactions, is described. Due to their tailored porous structure, these capsules possessed high drug loading efficiency, zero-order drug release kinetics and are also demonstrated to be used as nanoscale reactors for the prepareation of nanoparticles (NPs) without any external stabilizer. Moreover, owing to their intrinsic biocompatibility and fluorescence, these capsules exhibit promising prospect for biomedical applications. PMID:23820511

  9. Synthesis, characterization and properties of hollow nickel phosphide nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ni Yonghong; Tao Ali; Hu Guangzhi; Cao Xiaofeng; Wei Xianwen; Yang Zhousheng [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China)

    2006-10-14

    Nickel phosphide (Ni{sub 12}P{sub 5}) hollow nanospheres with a mean diameter of 100 nm and a shell thickness of 15-20 nm have been successfully prepared by a hydrothermal-microemulsion route, using NaH{sub 2}PO{sub 2} as a phosphorus source. XRD, EDS (HR)TEM, SEM and the SAED pattern were used to characterize the final product. Experiments showed that the as-prepared nickel phosphide hollow nanospheres could selectively catalytically degrade some organic dyes such as methyl red and Safranine T under 254 nm UV light irradiation. At the same time, the nickel phosphide hollow nanospheres showed a stronger ability to promote electron transfer between the glass-carbon electrode and adrenalin than nickel phosphide honeycomb-like particles prepared by a simple hydrothermal route. A possible formation process for nickel phosphide hollow nanospheres was suggested based on the experimental results.

  10. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul

    2013-08-07

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  11. Hollow bunches production

    CERN Document Server

    Hancock, S

    2017-01-01

    Hollow bunches address the issue of high-brightnessbeams suffering from transverse emittance growth in a strongspace charge regime. During the Proton Synchrotron (PS)injection plateau, the negative space charge tune shift canpush the beam onto theQy=6integer resonance. Modify-ing the longitudinal bunch profile in order to reduce the peakline charge density alleviates the detrimental impact of spacecharge. To this end we first produce longitudinally hollowphase space distributions in the PS Booster by exciting aparametric resonance with the phase loop feedback system.These inherently flat bunches are then transferred to the PS,where the beam becomes less prone to the emittance growthcaused by the integer resonance.During the late 2016 machine development sessions inthe PS Booster we profited from solved issues from 2015and managed to reliably extract hollow bunches of1.3eVsmatched longitudinal area. Furthermore, first results to cre-ate hollow bunches with larger longitudinal emittances to-wards the LHC Inject...

  12. Femtosecond Kerr-lens autocorrelation.

    Science.gov (United States)

    Sheik-Bahae, M

    1997-03-15

    An autocorrelation measurement of femtosecond laser pulse duration using the Kerr-lens mechanism is demonstrated. This technique can also be used as a sensitive and absolutely calibratable method for measuring ultrafast optical nonlinearities. A method that uses an electronic spectral-filtering scheme is proposed for determining the frequency chirp of pulses by interferometric autocorrelation.

  13. Formation of hollow atoms at metal- and insulator surfaces

    NARCIS (Netherlands)

    Morgenstern, R; Khemliche, H; Hoekstra, R

    1998-01-01

    The interaction of multiply charged ions with various surfaces gives rise to the formation of so-called hollow atoms via multiple electron capture into excited orbitals. The potential energy of the ions is partly converted into photons and kinetic energy of emitted electrons during subsequent decay

  14. Contact lens in keratoconus

    Directory of Open Access Journals (Sweden)

    Varsha M Rathi

    2013-01-01

    Full Text Available Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP lenses, soft and soft toric lenses, piggy back contact lenses (PBCL, hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL.

  15. Contact Lens Compliance

    OpenAIRE

    Jinabhai, A.

    2013-01-01

    Although contact lens-related complications are rare, and most are managed without any lasting side-effects, several reports have identified a variety of risk factors associated with lens wear complications. Among these risk factors, some are unalterable, such as age or gender. Others, however, are modifiable, for example, poor lens case hygiene or hand-washing and, therefore, can be targeted to maximise successful lens wear. This article reviews different aspects of contact lens non-compliance

  16. Metal oxide hollow nanoparticles formation by a single nanosecond pulsed laser ablation in liquid

    Science.gov (United States)

    Zhang, Tao; Wang, Zhen; Hwang, David J.

    2017-10-01

    In this study, the trend of metal oxide hollow nanoparticles formation is experimentally inspected by a single nanosecond pulsed laser ablation of a bulk metal material in water and/or ethanol. Analysis results by transmission electron microscope indicate that the hollow formation can be completed or initiated by a single nanosecond laser pulse, dictated by the diffusive thermo-chemical and/or bubble-assisted assembly mechanisms, depending on the surrounding liquid medium and laser parameters. The results not only provide experimental clues to unveiling complex mechanisms involved with the hollow formation by the multiple laser shots but also will contribute to improving the hollow particle production efficiency.

  17. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  18. Synthesis and upconversion luminescence properties of YF3:Yb3+/Er3+ hollow nanofibers derived from Y2O3:Yb3+/Er3+ hollow nanofibers

    Science.gov (United States)

    Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2013-06-01

    YF3:Yb3+/Er3+ hollow nanofibers were successfully fabricated via fluorination of the relevant Y2O3:Yb3+/Er3+ hollow nanofibers which were obtained by calcining the electrospun PVP/[Y(NO3)3 + Yb(NO3)3 + Er(NO3)3] composite nanofibers. The morphology and properties of the products were investigated in detail by X-ray diffraction, scanning electron microscope, transmission electron microscope, and fluorescence spectrometer. YF3:Yb3+/Er3+ hollow nanofibers were pure orthorhombic phase with space group Pnma and were hollow-centered structure with mean diameter of 174 ± 22 nm, and YF3:Yb3+/Er3+ hollow nanofibers are composed of nanoparticles with size in the range of 30-60 nm. Upconversion emission spectrum analysis manifested that YF3:Yb3+/Er3+ hollow nanofibers emitted strong green and weak red upconversion emissions centering at 523, 545, and 654 nm, respectively. The green and red emissions were, respectively, originated from 2H11/2/4S3/2 → 4I15/2 and 4F9/2 → 4Il5/2 energy levels transitions of the Er3+ ions. Moreover, the emitting colors of YF3:Yb3+/Er3+ hollow nanofibers were located in the green region in CIE chromaticity coordinates diagram. This preparation technique could be applied to prepare other rare earth fluoride upconversion luminescence hollow nanofibers.

  19. Ultrafast laser driven micro-lens to focus and energy select MeV protons

    Energy Technology Data Exchange (ETDEWEB)

    Toncian, Toma

    2008-05-15

    A technique for simultaneous focusing and energy selection of high-current, MeV proton beams using radial, transient electric fields (10{sup 7}-10{sup 10} V/m) triggered on the inner wall of a hollow micro-cylinder by an intense, sub-picosecond laser-pulse is presented. Due to the transient nature of the radial focusing field, the proposed method allows selection of a desired range out of the spectrum of the poly-energetic proton beam. This technique addresses current drawbacks of laser-accelerated proton beams, i.e. their broad spectrum and divergence at the source. This thesis presents both experimental and computational studies that led to the understanding of the physical processes driving the micro-lens. After an one side irradiation of a hollow metallic cylinder a radial electric field develops inside the cylinder. Hot electrons generated by the interaction between laser pulse and cylinder wall spread inside the cylinder generating a plasma at the wall. This plasma expands into vacuum and sustains an electric field that acts as a collecting lens on a proton beam propagating axially through the cylinder. Both focusing and the reduction of the intrinsic beam divergence from 20 deg to.3 deg for a narrow spectral range was demonstrated. By sub-aperturing the beam a narrow spectral range ({delta}{epsilon}/{epsilon} < 3%) was selected from the poly-energetic beam. The micro-lens properties are tunable allowing for optimization towards applications. Optical probing techniques and proton imaging were employed to study the spacial and temporal evolution of the field and revealed a complex physical scenario of the rise and decay of the radial electric field. Each aspect studied experimentally is interpreted using 2D PIC and ray tracing simulations. A very good agreement between the experimental and computational data is found. The PIC simulations are used to upscale the demonstrated micro-lens capabilities to the focusing of a 270 MeV proton beam, an energy relevant

  20. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... lens. In Butler's case, the lenses caused an infection and left her with a corneal abrasion. "I ... lenses? Sep 13, 2017 Contact Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally ...

  1. Formation and Stability of Hollow MgO Nanoshells

    NARCIS (Netherlands)

    Krishnan, G.; Palasantzas, G.; Kooi, B.J.

    High temperature annealing of gas phase synthesized Mg nanoparticles surrounded by an MgO shell leads to formation of hollow MgO nanoshells due to the evaporation assisted Kirkendall effect. Under electron beam exposure in TEM, the (220) MgO facets reduce their high surface energy by forming cube

  2. Anionic ligand assisted synthesis of 3-D hollow TiO2 architecture with enhanced photoelectrochemical performance.

    Science.gov (United States)

    Shin, Seong Sik; Kim, Dong Wook; Park, Jong Hoon; Kim, Dong Hoe; Kim, Ju Seong; Hong, Kug Sun; Cho, In Sun

    2014-12-30

    Hollow structured materials have shown great advantages for use in photoelectrochemical devices. However, their poor charge transport limits overall device performance. Here, we report a unique 3-D hollow architecture of TiO2 that greatly improves charge transport properties. We found that citric acid (CA) plays crucial roles in the formation of the 3-D hollow architecture. First, CA controls the hydrolysis rate of Ti ions and facilitates surface hydrolysis on templates during hydrothermal synthesis. Second, CA suppresses the growth of the carbon template at the initial reaction stage, resulting in the formation of comparatively small hollow fibers. More importantly, a prolonged hydrothermal reaction with CA enables a hollow sphere to grow into entangled hollow fibers via biomimetic swallowing growth. To demonstrate advantages of the 3-D hollow architecture for photoelectrochemical devices, we evaluated its photoelectrochemical performance, specifically the electrolyte diffusion and electron dynamics, by employing dye-sensitized solar cells as a model device. A systemic analysis reveals that the 3-D hollow architecture greatly improves both the electrolyte diffusion and electron transport compared to those of the nanoparticle and hollow sphere due to the elongated porous hollow morphology as well as the densely interconnected nanoparticles at the wall layer.

  3. Hollow micro/nanomaterials as nanoreactors for photocatalysis

    Directory of Open Access Journals (Sweden)

    Xiaobo Li

    2013-10-01

    Full Text Available Learning from nature, one of the most prominent goals of photocatalysis is to assemble multifunctional photocatalytic units in an integrated, high performance device that is capable of using solar energy to produce “solar hydrogen” from aqueous media. By analogy with natural systems it is clear that scaffolds with multi-scale structural architectures are necessary. In this perspective, recent progress related to the use of hollow micro/nanomaterials as nanoreactors for photocatalysis is discussed. Organised, multi-scale assemblies of photocatalytic units on hollow scaffolds is an emerging area that shows much promise for the synthesis of high performance photocatalysts. Not only do improved transport and diffusion characteristics play an import role, but increased electron/hole separation lifetimes as well as improved light harvesting characteristics by the hollow structures also do so and are touched upon in this short perspective.

  4. The use of hollow cathodes in deposition processes: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Muhl, Stephen, E-mail: muhl@unam.mx; Pérez, Argelia

    2015-03-31

    The first report of a discharge in a hollow cathode was by F. Paschen in 1916. That study showed that such a system was capable of producing a high electron flux and relatively low ion and neutral temperatures. About 40 years later, the work of Lidsky and others showed that hollow cathode arc discharges were one of the best plasma sources available at that time. The term “hollow cathode discharges” has commonly been used in reference to almost any discharge in a cathode with a cavity-like geometry, such that the plasma was enclosed or partially bound by the electrode walls that were at the cathode potential. Just as the magnetic field trapping of the electrons in a magnetron cathode results in an increase in the plasma density, in the hollow cathode, the reduced electron loss due to the geometry of the cathode also results in a higher plasma density. At least three types of discharge can be established in a hollow cathode. At low power and/or at relatively low gas pressures, the plasma is a “conventional” discharge characterized by low currents and medium to high voltages (we will call this a discharge in a hollow cathode or D-HC). Even this type of plasma has a higher density than a normal planar parallel-plate or magnetron system because the hollow geometry strongly reduces the loss of electrons. Using an adequate combination of gas pressure and applied power with a given hollow cathode diameter, or separation of the cathode surface, the negative glow of the plasma can expand to occupy the majority of the interior volume of the cathode. Under this condition the plasma current can, for the same voltage, be 100 to 1000 times the value of the “simple” D-HC discharge, and the plasma density is correspondingly larger (we call this a hollow cathode discharge or HCD). If the cathode is not cooled, the discharge can transform into a dispersed arc as the electrode temperature increases and thermal-field electron emission becomes an important additional source

  5. Contact lens in keratoconus

    OpenAIRE

    Rathi, Varsha M; Preeji S Mandathara; Srikanth Dumpati

    2013-01-01

    Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the En...

  6. REFRACTIVE NEUTRON LENS

    OpenAIRE

    Petrov, P. V.; Kolchevsky, N. N.

    2013-01-01

    Compound concave refractive lenses are used for focusing neutron beam. Investigations of spectral and focusing properties of a refractive neutron lens are presented. Resolution of the imaging system on the base of refractive neutron lenses depends on material properties and parameters of neutron source. Model of refractive neutron lens are proposed. Results of calculation diffraction resolution and focal depth of refractive neutron lens are discussed.

  7. Hollow-tip scanning photoelectron microscopy

    Science.gov (United States)

    Cherkun, A. P.; Mironov, B. N.; Aseyev, S. A.; Chekalin, S. V.

    2014-07-01

    A new type of microscopy based on scanning in vacuum by a beam of charged particles transmitted through a hollow probe has been implemented. This approach provides controllable motion of spatially localized ion, electron, molecular (atomic), and soft X-ray beams and investigation of the surface in the shear force mode. In the photoelectron mode, in which electrons are transmitted through a 2-μm quartz capillary, a surface profile of gadolinium irradiated by 400-nm femtosecond laser pulses has been visualized with a subwave spatial resolution. The new method of microscopy opens an opportunity of investigations in the field of nanometer local photodesorption of molecular ions (one of the last ideas of V.S. Letokhov).

  8. Co-Flow Hollow Cathode Technology

    Science.gov (United States)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  9. One-pot template-free synthesis of uniform-sized fullerene-like magnetite hollow spheres

    Science.gov (United States)

    Zhu, Qing; Zhang, Yue; Liu, Zheng; Zhou, Xinrui; Zhang, Xinmei; Zeng, Lintao

    2015-11-01

    Uniform-sized Fe3O4 hollow spheres with average diameter of 250 nm and shell thickness of ∼50 nm have been successfully synthesized through a simple hydrothermal route with the presence of di-n-propylamine (DPA) as a weak-base. The reaction time and DPA amount play important roles in the formation of the magnetite hollow spheres. The structures of the products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The results show that the single-crystalline Fe3O4 hollow spheres are composed of well-aligned magnetite nanoparticles (NPs). The magnetic property investigation shows that these hollow spheres have a higher saturation magnetization (Ms) than the solid spheres. Furthermore, a possible mechanism for the formation of magnetite hollow spheres is proposed based on the experimental observations.

  10. Morphology conserving aminopropyl functionalization of hollow silica nanospheres in toluene

    Science.gov (United States)

    Dobó, Dorina G.; Berkesi, Dániel; Kukovecz, Ákos

    2017-07-01

    Inorganic nanostructures containing cavities of monodisperse diameter distribution find applications in e.g. catalysis, adsorption and drug delivery. One of their possible synthesis routes is the template assisted core-shell synthesis. We synthesized hollow silica spheres around polystyrene cores by the sol-gel method. The polystyrene template was removed by heat treatment leaving behind a hollow spherical shell structure. The surface of the spheres was then modified by adding aminopropyl groups. Here we present the first experimental evidence that toluene is a suitable alternative functionalization medium for the resulting thin shells, and report the comprehensive characterization of the amino-functionalized hollow silica spheres based on scanning electron microscopy, transmission electron microscopy, N2 adsorption, FT-IR spectroscopy, Raman spectroscopy and electrokinetic potential measurement. Both the presence of the amino groups and the preservation of the hollow spherical morphology were unambiguously proven. The introduction of the amine functionality adds amphoteric character to the shell as shown by the zeta potential vs. pH function. Unlike pristine silica particles, amino-functionalized nanosphere aqueous sols can be stable at both acidic and basic conditions.

  11. Hollow waveguide for urology treatment

    Science.gov (United States)

    Jelínková, H.; Němec, M.; Koranda, P.; Pokorný, J.; Kőhler, O.; Drlík, P.; Miyagi, M.; Iwai, K.; Matsuura, Y.

    2010-02-01

    The aim of our work was the application of the special sealed hollow waveguide system for the urology treatment - In our experimental study we have compared the effects of Ho:YAG (wavelength 2100 nm) and Er:YAG (wavelength 2940 nm) laser radiation both on human urinary stones (or compressed plaster samples which serve as a model) fragmentation and soft ureter tissue incision in vitro. Cyclic Olefin Polymer - coated silver (COP/Ag) hollow glass waveguides with inner and outer diameters 700 and 850 μm, respectively, were used for the experiment. To prevent any liquid to diminish and stop the transmission, the waveguide termination was utilized.

  12. Quartz antenna with hollow conductor

    Science.gov (United States)

    Leung, Ka-Ngo; Benabou, Elie

    2002-01-01

    A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

  13. Hollow Force, Hollow Metaphor: Assessing The Current Defense Drawdown

    Science.gov (United States)

    2016-04-04

    of a period of war and the threats diminish and everyone starts cutting the hell out of the defense budget….we are not going to hollow out the force...and tactical unit performance at the National Training Center. Henderson concluded that structural barriers and adopted practices in the new All

  14. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... level of care or consideration as a standard contact lens because they can be purchased over-the-counter ... Teenager Blinded In One Eye By Non-Prescription Contact Lens Laura: Vision Loss After Just 10 Hours Robyn: ...

  15. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct 31, 2016 What You Should Know About Swimming and Your Eyes Aug 16, 2016 5 Steps to Healthy Contact Lens Use May 31, 2016 More Eye Health News Eyeglasses May One Day Treat Glaucoma JAN 18, ...

  16. Artificial crystalline lens

    NARCIS (Netherlands)

    Norrby, S.; Koopmans, S.; Terwee, T.

    2006-01-01

    Replacement of the crystalline lens with a synthetic soft material (ACL) has been shown to produce 3 to 5 D of accommodation following pharmacologic stimulation in primates for up to 1 year postoperatively. The eyes were relatively clear, suggesting that an injectable synthetic lens is a feasible

  17. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct 31, 2016 What You Should Know About Swimming and Your Eyes Aug 16, 2016 5 Steps to Healthy Contact Lens Use May 31, 2016 More Eye Health News Top ...

  18. Studies on poly (vinyl chloride/silica dioxide composite hollow fiber membrane

    Directory of Open Access Journals (Sweden)

    Mei Shuo

    2016-01-01

    Full Text Available Poly (vinyl chloride/silica dioxide composite hollow fiber membranes were prepared by using the method of immersion-precipitation process. The influences of stretching ratio on the formation of the interfacial microporous of poly (vinyl chloride/silica dioxide composite hollow fiber membranes were specifically investigated by scanning electron microscope, dynamic mechanical analysis, and finite element method. Results show that with the stretching ratio increasing, numerous IFM appear on the surface of membranes. Finite element method actually reflects the dynamic change of microporous structure of poly (vinyl chloride/silica dioxide composite hollow fiber membranes.

  19. Contact lens hygiene compliance and lens case contamination: A review.

    Science.gov (United States)

    Wu, Yvonne Tzu-Ying; Willcox, Mark; Zhu, Hua; Stapleton, Fiona

    2015-10-01

    A contaminated contact lens case can act as a reservoir for microorganisms that could potentially compromise contact lens wear and lead to sight threatening adverse events. The rate, level and profile of microbial contamination in lens cases, compliance and other risk factors associated with lens case contamination, and the challenges currently faced in this field are discussed. The rate of lens case contamination is commonly over 50%. Coagulase-negative Staphylococcus, Bacillus spp., Pseudomonas aeruginosa and Serratia marcescens are frequently recovered from lens cases. In addition, we provide suggestions regarding how to clean contact lens cases and improve lens wearers' compliance as well as future lens case design for reducing lens case contamination. This review highlights the challenges in reducing the level of microbial contamination which require an industry wide approach. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  20. Synthesis and characterization of hollow spherical copper phosphide (Cu 3P) nanopowders

    Science.gov (United States)

    Liu, Shuling; Qian, Yitai; Xu, Liqiang

    2009-03-01

    In this paper, hollow spherical Cu 3P nanopowders were synthesized by using copper sulfate pentahydrate (CuSO 4ṡ5H 2O) and yellow phosphorus in a mixed solvent of glycol, ethanol and water at 140-180 ∘C for 12 h. X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), electron diffraction pattern (ED) and transmission electronic microscopy (TEM) studies show that the as-synthesized nanocrystal is pure hexagonal phase Cu 3P with a hollow spherical morphology. Based on the TEM observations, a possible aggregation growth mechanism was proposed for the formation of Cu 3P hollow structures. Meanwhile, the effects of some key factors such as solvents, reaction temperature and reaction time on the final formation of the Cu 3P hollow structure were also discussed.

  1. Rethinking contact lens aftercare.

    Science.gov (United States)

    Efron, Nathan; Morgan, Philip B

    2017-09-01

    The evolution of contact lens technology and clinical practice over the past three decades has been remarkable, with dramatic improvements in material biocompatibility, better lens designs and care systems, and more flexible and convenient modalities of wear. However, our approach to the aftercare examination has remained conservative, with the general modus operandi having not fully evolved from the difficult, early years of fitting non-regular replacement rigid and low water content hydrogel lenses. In this paper, we review current aftercare practice and in particular, the preferred frequency that lens wearers should return for routine visits and the appropriateness of regulations governing contact lens prescription expiry. Four key clinical reasons for conducting a routine aftercare visit are identified: preserving ocular health, maintaining good vision, optimising comfort and ensuring satisfactory lens fitting performance. Commercial reasons for conducting aftercare visits are also considered. A decision matrix is presented to help practitioners decide on an appropriate time interval between routine aftercare visits. The first aftercare visit should always take place within one to two weeks of lens dispensing. After this, the following time intervals between routine aftercare visits are advised as a general guideline: soft daily disposable, 24 months; soft daily reusable and rigid daily wear, 12 months; soft and rigid extended wear, six months. These aftercare visit frequencies may need to be adjusted when rapid rates of refractive change are anticipated, such as every six months during child/teenager myopic progression and every 12 months during the advancement of presbyopia. Numerous clinical caveats for varying these recommended aftercare frequencies are also discussed. Those new to lens wear should be seen within the first two months of lens dispensing. Regulatory authorities charged with the responsibility of stipulating the validity of a contact

  2. One-pot template-free synthesis of uniform-sized fullerene-like magnetite hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Qing; Zhang, Yue, E-mail: 273551472@qq.com; Liu, Zheng; Zhou, Xinrui; Zhang, Xinmei; Zeng, Lintao

    2015-11-30

    Graphical abstract: Uniform-sized Fe{sub 3}O{sub 4} hollow spheres with average diameter of 250 nm and shell thickness of ∼50 nm have been successfully synthesized through a simple hydrothermal route with the presence of di-n-propylamine (DPA) as a weak-base. The magnetic property investigation shows that these hollow spheres have a higher saturation magnetization (M{sub s}) than the solid spheres. Furthermore, a possible mechanism for the formation of magnetite hollow spheres is proposed based on the experimental observations. - Highlights: • Uniform-sized Fe{sub 3}O{sub 4} hollow microspheres were prepared by a hydrothermal method. • The used reagent di-n-propylamine made it easy for further surface modification. • The saturation magnetization of hollow spheres was higher than that of solid ones. • The formation mechanism was discussed. • This method provides a convenient way to fabricate other hollow ferrite spheres. - Abstract: Uniform-sized Fe{sub 3}O{sub 4} hollow spheres with average diameter of 250 nm and shell thickness of ∼50 nm have been successfully synthesized through a simple hydrothermal route with the presence of di-n-propylamine (DPA) as a weak-base. The reaction time and DPA amount play important roles in the formation of the magnetite hollow spheres. The structures of the products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The results show that the single-crystalline Fe{sub 3}O{sub 4} hollow spheres are composed of well-aligned magnetite nanoparticles (NPs). The magnetic property investigation shows that these hollow spheres have a higher saturation magnetization (M{sub s}) than the solid spheres. Furthermore, a possible mechanism for the formation of magnetite hollow spheres is proposed based on the experimental observations.

  3. Review of small aspheric glass lens molding technologies

    Science.gov (United States)

    Yin, Shaohui; Jia, Hongpeng; Zhang, Guanhua; Chen, Fengjun; Zhu, Kejun

    2017-03-01

    Aspheric lens can eliminate spherical aberrations, coma, astigmatism, field distortions, and other adverse factors. This type of lens can also reduce the loss of light energy and obtain high-quality images and optical characteristics. The demand for aspheric lens has increased in recent years because of its advantageous use in the electronics industry, particularly for compact, portable devices and high-performance products. As an advanced manufacturing technology, the glass lens molding process has been recognized as a low-cost and high-efficiency manufacturing technology for machining small-diameter aspheric lens for industrial production. However, the residual stress and profile deviation of the glass lens are greatly affected by various key technologies for glass lens molding, including glass and mold-die material forming, mold-die machining, and lens molding. These key technical factors, which affect the quality of the glass lens molding process, are systematically discussed and reviewed to solve the existing technical bottlenecks and problems, as well as to predict the potential applicability of glass lens molding in the future.

  4. Role of Aquaporin 0 in lens biomechanics.

    Science.gov (United States)

    Sindhu Kumari, S; Gupta, Neha; Shiels, Alan; FitzGerald, Paul G; Menon, Anil G; Mathias, Richard T; Varadaraj, Kulandaiappan

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5(-/-)), AQP0 KO (heterozygous KO: AQP0(+/-); homozygous KO: AQP0(-/-); all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0(+/-) lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer

  5. Hollow Nanospheres Array Fabrication via Nano-Conglutination Technology.

    Science.gov (United States)

    Zhang, Man; Deng, Qiling; Xia, Liangping; Shi, Lifang; Cao, Axiu; Pang, Hui; Hu, Song

    2015-09-01

    Hollow nanospheres array is a special nanostructure with great applications in photonics, electronics and biochemistry. The nanofabrication technique with high resolution is crucial to nanosciences and nano-technology. This paper presents a novel nonconventional nano-conglutination technology combining polystyrenes spheres (PSs) self-assembly, conglutination and a lift-off process to fabricate the hollow nanospheres array with nanoholes. A self-assembly monolayer of PSs was stuck off from the quartz wafer by the thiol-ene adhesive material, and then the PSs was removed via a lift-off process and the hollow nanospheres embedded into the thiol-ene substrate was obtained. Thiolene polymer is a UV-curable material via "click chemistry" reaction at ambient conditions without the oxygen inhibition, which has excellent chemical and physical properties to be attractive as the adhesive material in nano-conglutination technology. Using the technique, a hollow nanospheres array with the nanoholes at the diameter of 200 nm embedded into the rigid thiol-ene substrate was fabricated, which has great potential to serve as a reaction container, catalyst and surface enhanced Raman scattering substrate.

  6. Telescopic vision contact lens

    Science.gov (United States)

    Tremblay, Eric J.; Beer, R. Dirk; Arianpour, Ashkan; Ford, Joseph E.

    2011-03-01

    We present the concept, optical design, and first proof of principle experimental results for a telescopic contact lens intended to become a visual aid for age-related macular degeneration (AMD), providing magnification to the user without surgery or external head-mounted optics. Our contact lens optical system can provide a combination of telescopic and non-magnified vision through two independent optical paths through the contact lens. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8x - 3x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision.

  7. Role of Aquaporin 0 in lens biomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Sindhu Kumari, S.; Gupta, Neha [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); Shiels, Alan [Washington University School of Medicine, St. Louis, MO (United States); FitzGerald, Paul G. [Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA (United States); Menon, Anil G. [University of Cincinnati College of Medicine, Cincinnati, OH (United States); Mathias, Richard T. [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States); Varadaraj, Kulandaiappan, E-mail: kulandaiappan.varadaraj@stonybrook.edu [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States)

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5{sup −/−}), AQP0 KO (heterozygous KO: AQP0{sup +/−}; homozygous KO: AQP0{sup −/−}; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0{sup +/−} lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and

  8. Uniform hollow magnetite spheres: Facile synthesis, growth mechanism, and their magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xing, E-mail: xzhou@mail.usts.edu.cn [School of Chemistry, Biology and Material Engineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Research Center for Engineering Technology of Polymeric Composites of Shanxi Province, North University of China, Taiyuan 030051 (China); Zhao, Guizhe [Research Center for Engineering Technology of Polymeric Composites of Shanxi Province, North University of China, Taiyuan 030051 (China); Liu, Yaqing, E-mail: zfflyq98@163.com [Research Center for Engineering Technology of Polymeric Composites of Shanxi Province, North University of China, Taiyuan 030051 (China)

    2014-11-15

    Highlights: • Uniform Fe{sub 3}O{sub 4} hollow spheres with high saturation magnetization were synthesized through a simple solvothermal process. • Without using any hard templates or external magnetic field. • The as-prepared magnetite hollow spheres exhibit a ferromagnetic behavior with high Ms of ca. 85.9 emu/g at room temperature. • The morphology of Fe{sub 3}O{sub 4} with nanoparticles, hollow, and irregular structures could be adjusted by changing the reactive conditions. - Abstract: Hierarchical porous Fe{sub 3}O{sub 4} hollow spheres with high saturation magnetization were synthesized through a simple solvothermal process in ethylene glycol (EG) in the presence of Tetrabutylammonium chloride (TBAC) and urea. By investigating the effect of reaction temperature, time, the amount of urea, and concentration of iron ion on the formation of hollow spheres, it was proposed that the main formation mechanism of hollow spheres is Ostwald ripening process combined with assembly-then-inside-out evacuation process. Additionally, it is found that the morphology of Fe{sub 3}O{sub 4} with nanoparticles, hollow, and irregular structures could be adjusted by changing the above factors. The resulting products were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). The hierarchical porous Fe{sub 3}O{sub 4} hollow spheres exhibited enhanced saturation magnetization as compared with Fe{sub 3}O{sub 4} nanoparticles.

  9. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... with Colored Contact Lenses Julian: Teenager Blinded In One Eye By Non-Prescription Contact Lens Laura: Vision ... Robyn: Blurry Vision and Daily Eye Drops After One Use Facts About Colored Contacts and Halloween Safety ...

  10. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... glow-in-the-dark lizard lenses, costume contacts can certainly add a spooky, eye-popping touch. But ... consideration as a standard contact lens because they can be purchased over-the-counter or on the ...

  11. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Purchase the colored contact lenses from an eye product retailer who asks for a prescription. Follow the contact lens care directions for cleaning, disinfecting, and wearing the lenses. Never share contact ...

  12. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses ...

  13. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Contact Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent ... tech and from super cool to super gross. New treatment possibilities were a feel-good favorite. But ...

  14. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Eye By Non-Prescription Contact Lens Laura: Vision Loss After Just 10 Hours Robyn: Blurry Vision and ... Therapy Approved to Treat Rare Cause of Vision Loss DEC 21, 2017 By Dan Gudgel The U.S. ...

  15. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Contact Lens Facts Over-the-Counter Costume Contacts May Contain Chemicals Harmful to Eyes Four Ways Over- ... without a prescription are breaking the law, and may be fined $11,000 per violation. "Many of ...

  16. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... had not been properly fitted by an eye care professional, the lenses stuck to my eye like ... lenses do not require the same level of care or consideration as a standard contact lens because ...

  17. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct ...

  18. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... impulsive buy from a souvenir shop, but 10 hours after she first put in a pair of ... Contact Lens Laura: Vision Loss After Just 10 Hours Robyn: Blurry Vision and Daily Eye Drops After ...

  19. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... Costume Contact Lenses Can Ruin Vision Eye Makeup Safety In fact, it is illegal to sell colored ...

  20. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Contact Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent ... at bedtime, can significantly slow the progression o… New Dry Eye Treatment is a Tear-Jerker JUL ...

  1. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... new application of artificial intelligence shows whether a patient’s eyes point to high blood pressure or risk ...

  2. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Vision and Daily Eye Drops After One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume Contacts May Contain Chemicals ...

  3. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... in a pair of colored contact lenses, Laura Butler of Parkersburg, W.Va., had "extreme pain in ... to wear any kind of contact lens. In Butler's case, the lenses caused an infection and left ...

  4. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ... ask for a prescription. There is no such thing as a "one size fits all" contact lens. ...

  5. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct ... Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American Academy of Ophthalmology 2017 ...

  6. Viscous froth lens

    Science.gov (United States)

    Green, T. E.; Bramley, A.; Lue, L.; Grassia, P.

    2006-11-01

    Microscale models of foam structure traditionally incorporate a balance between bubble pressures and surface tension forces associated with curvature of bubble films. In particular, models for flowing foam microrheology have assumed this balance is maintained under the action of some externally imposed motion. Recently, however, a dynamic model for foam structure has been proposed, the viscous froth model, which balances the net effect of bubble pressures and surface tension to viscous dissipation forces: this permits the description of fast-flowing foam. This contribution examines the behavior of the viscous froth model when applied to a paradigm problem with a particularly simple geometry: namely, a two-dimensional bubble “lens.” The lens consists of a channel partly filled by a bubble (known as the “lens bubble”) which contacts one channel wall. An additional film (known as the “spanning film”) connects to this bubble spanning the distance from the opposite channel wall. This simple structure can be set in motion and deformed out of equilibrium by applying a pressure across the spanning film: a rich dynamical behavior results. Solutions for the lens structure steadily propagating along the channel can be computed by the viscous froth model. Perturbation solutions are obtained in the limit of a lens structure with weak applied pressures, while numerical solutions are available for higher pressures. These steadily propagating solutions suggest that small lenses move faster than large ones, while both small and large lens bubbles are quite resistant to deformation, at least for weak applied back pressures. As the applied back pressure grows, the structure with the small lens bubble remains relatively stiff, while that with the large lens bubble becomes much more compliant. However, with even further increases in the applied back pressure, a critical pressure appears to exist for which the steady-state structure loses stability and unsteady

  7. Fabrication of Metallic Hollow Nanoparticles

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  8. Low-temperature template-free synthesis of Cu 2O hollow spheres

    Science.gov (United States)

    Sui, Yongming; Zhang, Yanyan; Fu, Wuyou; Yang, Haibin; Zhao, Qiang; Sun, Peng; Ma, Dong; Yuan, Mingxia; Li, Yixing; Zou, Guangtian

    2009-04-01

    Cuprous oxide (Cu 2O) hollow spheres have been successfully prepared via a template-free hydrothermal method with the assistance of poly(vinylprrolidone) (PVP) at 90 °C. The structure and morphology of the Cu 2O hollow spheres were characterized by X-ray diffraction, field-emission scanning electron microscope, and transmission electron microscope. The as-prepared hollow spheres are cubic phase Cu 2O. The as-prepared products have a hollow sphere structure with outer diameters of 400-700 nm and the thickness of shells is about 40-70 nm. Poly(vinylprrolidone) is employed for the first time to improve the stabilization of crystalline phase occurred at a rate commensurate with localized Ostwald ripening and self-transformation for producing Cu 2O hollow spheres. A possible PVP-assisted Ostwald ripening process is proposed for the formation of Cu 2O hollow spheres on the basis of intermediate products at different growth stages.

  9. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  10. TESS Lens-Bezel Assembly Modal Testing

    Science.gov (United States)

    Dilworth, Brandon J.; Karlicek, Alexandra

    2017-01-01

    The Transiting Exoplanet Survey Satellite (TESS) program, led by the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology (MIT) will be the first-ever spaceborne all-sky transit survey. MIT Lincoln Laboratory is responsible for the cameras, including the lens assemblies, detector assemblies, lens hoods, and camera mounts. TESS is scheduled to be launched in August of 2017 with the primary goal to detect small planets with bright host starts in the solar neighborhood, so that detailed characterizations of the planets and their atmospheres can be performed. The TESS payload consists of four identical cameras and a data handling unit. Each camera consists of a lens assembly with seven optical elements and a detector assembly with four charge-coupled devices (CCDs) including their associated electronics. The optical prescription requires that several of the lenses are in close proximity to a neighboring element. A finite element model (FEM) was developed to estimate the relative deflections between each lens-bezel assembly under launch loads to predict that there are adequate clearances preventing the lenses from making contact. Modal tests using non-contact response measurements were conducted to experimentally estimate the modal parameters of the lens-bezel assembly, and used to validate the initial FEM assumptions. Key Words Non-contact measurements, modal analysis, model validation

  11. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  12. Space charge mitigation with longitudinally hollow bunches

    CERN Document Server

    AUTHOR|(CDS)2088716; Hancock, Steven; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  13. Method to fabricate hollow microneedle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kravitz, Stanley H. (Placitas, NM); Ingersoll, David (Albuquerque, NM); Schmidt, Carrie (Los Lunas, NM); Flemming, Jeb (Albuquerque, NM)

    2006-11-07

    An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

  14. A novel method for preparation of hollow and solid carbon spheres

    Indian Academy of Sciences (India)

    Wintec

    Abstract. Hollow and solid carbon spheres were prepared by the reaction of ferrocene and ammonium carbo- nate in a sealed quartz tube at 500°C. The morphology and microstructure of the product were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron ...

  15. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  16. Mechanical 144 GHz beam steering with all-metallic epsilon-near-zero lens antenna

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco-Peña, V., E-mail: victor.pacheco@unavarra.es; Torres, V., E-mail: victor.torres@unavarra.es; Orazbayev, B., E-mail: b.orazbayev@unavarra.es; Beruete, M., E-mail: miguel.beruete@unavarra.es; Sorolla, M. [Antennas Group-TERALAB, Universidad Pública de Navarra, Campus Arrosadía, 31006 Pamplona (Spain); Navarro-Cía, M., E-mail: m.navarro@imperial.ac.uk [Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2BT (United Kingdom); Centre for Plasmonics and Metamaterials, Imperial College London, London SW7 2AZ (United Kingdom); Centre for Terahertz Science and Engineering, Imperial College London, London SW7 2AZ (United Kingdom); Engheta, N., E-mail: engheta@ee.upenn.edu [Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2014-12-15

    An all-metallic steerable beam antenna composed of an ε-near-zero (ENZ) metamaterial lens is experimentally demonstrated at 144 GHz (λ{sub 0} = 2.083 mm). The ENZ lens is realized by an array of narrow hollow rectangular waveguides working just near and above the cut-off of the TE{sub 10} mode. The lens focal arc on the xz-plane is initially estimated analytically as well as numerically and compared with experimental results demonstrating good agreement. Next, a flange-ended WR-6.5 waveguide is placed along the lens focal arc to evaluate the ENZ-lens antenna steerability. A gain scan loss below 3 dB is achieved for angles up to ±15°.

  17. Fabrication and upconversion luminescence properties of YF3:Er3+ hollow nanofibers via monoaxial electrospinning combined with fluorination method.

    Science.gov (United States)

    Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2014-06-01

    YF3:Er3+ hollow nanofibers were successfully fabricated via fluorination of the relevant Y2O3:Er3+ hollow nanofibers which were obtained by calcining the electrospun PVP/[Y(NO3)3 + Er(NO3)3] composite nanofibers. The morphology and properties of the products were investigated in detail by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and fluorescence spectrometer. YF3:Er3+ hollow nanofibers were pure orthorhombic phase with space group Pnma and were hollow-centered structure with the mean diameter of 172 +/- 23 nm, and YF3:Er3+ hollow nanofibers were composed of nanoparticles with the diameter ranging from 30 nm to 50 nm. Upconversion emission spectrum analysis manifested that YF3:Er3+ hollow nanofibers emitted strong green and weak red upconversion emission centering at 524 nm, 543 nm and 653 nm, respectively. The green emissions and the red emission were respectively originated from 2H11/2/4S3/2 --> 4I15/2 and 4F9/2 --> 4I15/2 energy levels transitions of the Er3+ ions. Moreover, the emitting colors of YF3:Er3+ hollow nanofibers were located in the green region in CIE chromaticity coordinates diagram. The luminescent intensity of YF3:Er3+ hollow nanofibers was increased remarkably with the increasing doping concentration of Er3+ ions. The possible formation mechanism of YF3:Er3+ upconversion luminescence hollow nanofibers was also discussed. This preparation technique could be applied to prepare other rare earth fluoride upconversion luminescence hollow nanofibers.

  18. Hierarchical Ag/AgCl-TiO{sub 2} hollow spheres with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu Long; Yin, Hao Yong [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Nie, Qiu Lin, E-mail: nieqiulin@hdu.edu.cn [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Wei Wei [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhang, Yang; LiYuan, Qiu [College of Science, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2017-01-01

    The hierarchical Ag/AgCl-TiO{sub 2} hollow spheres were synthesized by depositing Ag/AgCl nanoparticles on TiO{sub 2} hollow spheres via a precipitation photoreduction method, and they were further characterized using TGA, SEM, TEM, XRD, XPS, UV–vis DRS and photoelectric chemical analysis. The analysis showed that the hierarchical Ag/AgCl-TiO{sub 2} hollow spheres exhibited the highest photocatalytic activity, which was approximately 13 times higher than that of TiO{sub 2} hollow spheres. The high photocatalytic activity of the composites is due to efficient electron-hole pairs separation at the photocatalyst interfaces, and localized surface plasmon resonance of Ag nanoparticles formed on AgCl particles in the degradation reaction. - Highlights: • TiO{sub 2} hollow spheres were prepared by a sacrificial template method. • The hollow spheres were modified with Ag/AgCl to form the heterojunctions. • The modification may produce synergistic effect of LSPR and hollow structure. • Visible light photocatalytic activity was enhanced on this hollow catalyst. • The mechanism of the improved photocatalytic performance was discussed.

  19. Fabrication and characterization of functionally graded poly(vinylidine fluoride)-silver nanocomposite hollow fibers for sustainable water recovery

    KAUST Repository

    Francis, Lijo

    2014-12-01

    Poly(vinylidine fluoride) (PVDF) asymmetric hydrophobic hollow fibers were fabricated successfully using dryjet wet spinning. Hydrophobic silver nanoparticles were synthesized and impregnated into the PVDF polymer matrix and functionally graded PVDF-silver nanocomposite hollow fibers are fabricated and tested in the direct contact membrane distillation (DCMD) process. The as-synthesized silver nanoparticles were characterized for Transmission Electron Microscopy (TEM), particle size distribution (PSD) and Ultra Violet (UV) visible spectroscopy. Both the PVDF and PVDF-silver nanocomposite asymmetric hollow fibers were characterized for their morphology, water contact angle and mechanical strength. Addition of hydrophobic silver nanoparticles was found to enhance the hydrophobicity and ~ 2.5 fold increase the mechanical strength of the hollow fibers. A water vapor flux of 31.9kg m-2 h-1 was observed at a feed inlet temperature of 80 °C and at a permeate temperature of 20 °C in the case of hollow fiber membrane modules fabricated using PVDF hollow fibers; the water vapor flux was found to be increased by about 8% and to reach 34.6kg m-2 h-1 for the hollow fiber membrane modules fabricated from the PVDF-silver nanocomposite hollow fibers at the same operating conditions with 99.99% salt rejection.

  20. Hollow system with fin. Transient Green function method combination for two hollow cylinders

    Directory of Open Access Journals (Sweden)

    Buikis Andris

    2017-01-01

    Full Text Available In this paper we develop mathematical model for three dimensional heat equation for the system with hollow wall and fin and construct its analytical solution for two hollow cylindrical sample. The method of solution is based on Green function method for one hollow cylinder. On the conjugation conditions between both hollow cylinders we construct solution for system wall with fin. As result we come to integral equation on the surface between both hollow cylinders. Solution is obtained in the form of second kind Fredholm integral equation. The generalizing of Green function method allows us to use Green function method for regular non-canonical domains.

  1. Electron optics

    CERN Document Server

    Grivet, Pierre; Bertein, F; Castaing, R; Gauzit, M; Septier, Albert L

    1972-01-01

    Electron Optics, Second English Edition, Part I: Optics is a 10-chapter book that begins by elucidating the fundamental features and basic techniques of electron optics, as well as the distribution of potential and field in electrostatic lenses. This book then explains the field distribution in magnetic lenses; the optical properties of electrostatic and magnetic lenses; and the similarities and differences between glass optics and electron optics. Subsequent chapters focus on lens defects; some electrostatic lenses and triode guns; and magnetic lens models. The strong focusing lenses and pris

  2. Hollow plasmonic antennas for broadband SERS spectroscopy

    Directory of Open Access Journals (Sweden)

    Gabriele C. Messina

    2015-02-01

    Full Text Available The chemical environment of cells is an extremely complex and multifaceted system that includes many types of proteins, lipids, nucleic acids and various other components. With the final aim of studying these components in detail, we have developed multiband plasmonic antennas, which are suitable for highly sensitive surface enhanced Raman spectroscopy (SERS and are activated by a wide range of excitation wavelengths. The three-dimensional hollow nanoantennas were produced on an optical resist by a secondary electron lithography approach, generated by fast ion-beam milling on the polymer and then covered with silver in order to obtain plasmonic functionalities. The optical properties of these structures have been studied through finite element analysis simulations that demonstrated the presence of broadband absorption and multiband enhancement due to the unusual geometry of the antennas. The enhancement was confirmed by SERS measurements, which showed a large enhancement of the vibrational features both in the case of resonant excitation and out-of-resonance excitation. Such characteristics indicate that these structures are potential candidates for plasmonic enhancers in multifunctional opto-electronic biosensors.

  3. Hollow nanocrystals and method of making

    Science.gov (United States)

    Alivisatos, A Paul [Oakland, CA; Yin, Yadong [Moreno Valley, CA; Erdonmez, Can Kerem [Berkeley, CA

    2011-07-05

    Described herein are hollow nanocrystals having various shapes that can be produced by a simple chemical process. The hollow nanocrystals described herein may have a shell as thin as 0.5 nm and outside diameters that can be controlled by the process of making.

  4. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... an Ophthalmologist Patient Stories Español Eye Health / News Halloween Hazard: The Hidden Dangers of Buying Decorative Contact ... After One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter ...

  5. Contact Lens Risks

    Science.gov (United States)

    ... any lens solution. Do not expose your contact lenses to any water: tap, bottled, distilled, lake or ocean water. Never ... resistant to treatment and cure. Remove your contact lenses before swimming. ... in swimming pool water, hot tubs, lakes and the ocean Replace your ...

  6. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... in the United States. All contact lenses are medical devices that require a prescription and proper fitting by an eye-care professional. ... care professional such as an ophthalmologist — an eye medical doctor — who will ... a valid prescription that includes the brand name, lens measurements, and ...

  7. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... or in beauty salons, novelty shops or in pop-up Halloween stores are not FDA-approved and are ... Lens-Related Eye Infections Mar 01, 2017 New Technology Helps the Legally Blind Be More Independent Oct ...

  8. Modification of W surfaces by exposure to hollow cathode plasmas

    Science.gov (United States)

    Stancu, C.; Stokker-Cheregi, F.; Moldovan, A.; Dinescu, M.; Grisolia, C.; Dinescu, G.

    2017-10-01

    In this work, we assess the surface modifications induced on W samples following exposure to He and He/H2 radiofrequency plasmas in hollow cathode discharge configuration. Our study addresses issues that relate to the use of W in next-generation fusion reactors and, therefore, the investigation of W surface degradation following exposure and heating by plasmas to temperatures above 1000 °C is of practical importance. For these experiments, we used commercially available tungsten samples having areas of 30 × 15 mm and 0.1 mm thickness. The hollow cathode plasma was produced using a radiofrequency (RF) generator (13.56 MHz) between parallel plate electrodes. The W samples were mounted as one of the electrodes. The He and He/H2 plasma discharges had a combined effect of heating and bombardment of the W surfaces. The surface modifications were studied for discharge powers between 200 and 300 W, which resulted in the heating of the samples to temperatures between 950 and 1230 °C, respectively. The samples were weighed prior and after plasma exposure, and loss of mass was measured following plasma exposure times up to 90 min. The analysis of changes in surface morphology was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, optical emission spectra of the respective plasmas were recorded from the region localized inside the hollow cathode gap. We discuss the influence of experimental parameters on the changes in surface morphology.

  9. Clinical survey of lens care in contact lens patients.

    Science.gov (United States)

    Ky, W; Scherick, K; Stenson, S

    1998-10-01

    Overall, contact lenses provide a safe and effective modality for vision correction. However, problems do occasionally arise. Up to 80% of contact lens complications can be traced to poor patient compliance with recommended lens care guidelines. We conducted a survey to evaluate the level of patient compliance in specific areas of lens care and maintenance and to assess patient knowledge of basic contact lens information. Patients were asked to complete an anonymous 15 question survey that focused on lens care--specifically the use of contact lens cleaners, methods of disinfection, enzyme treatments, use of rewetting drops, and the frequency of follow-up exams. In addition, the survey included six true/false questions relating to contact lens care and safety. There were a total of 103 participants in the study. Approximately 24% of patients stated they never cleaned their lenses prior to disinfection, and 5% used saline solutions as their primary mode of disinfection. A sizable portion of those surveyed (43% of soft lens wearers and 71% of rigid gas permeable lens wearers) either never used enzyme cleaners or used them less than once a month. Seventy percent of patients either never used rewetting drops or used them less than once a day. Twenty-nine percent of patients consulted their eye care professionals every 2 years and 6% less often than every two years. Six questions assessed patient knowledge of contact lens care safety. Of a possible six out of six correct answers, the mean number of correct responses was 3.74. A sizable proportion of contact lens wearers do not adequately adhere to recommended contact lens care, and many have an inadequate understanding of contact lens care guidelines. Therefore, it is important that practitioners place more emphasis on patient education at the time of initial contact lens fitting and reinforce such instruction during follow-up visits.

  10. Synthesis and Characterization of Gd2O3 Hollow Microspheres Using a Template-Directed Method

    Science.gov (United States)

    Jiang, Xueliang; Yu, Lu; Yao, Chu; Zhang, Fuqing; Zhang, Jiao; Li, Chenjian

    2016-01-01

    Uniform rare-earth gadolinium oxide (Gd2O3) hollow microspheres, as formed through a urea-assisted homogenous precipitation process using carbon spheres as a template and a subsequent heat treatment, were characterized by using X-ray diffraction, Fourier transformed infared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Tellet surface area measurement. The results indicate that the final products can be indexed to a cubic Gd2O3 phase with high purity and have a uniform morphology at 500 nm in diameter and 20 nm in shell thickness. The as-synthesized Gd2O3 hollow microspheres exhibited a superior photooxidation activity to that of Gd2O3 powder and an effect similar to P25, significantly broadening the potential of Gd2O3 hollow microspheres for many practical applications. PMID:28773446

  11. Synthesis and Characterization of Gd2O3 Hollow Microspheres Using a Template-Directed Method

    Directory of Open Access Journals (Sweden)

    Xueliang Jiang

    2016-04-01

    Full Text Available Uniform rare-earth gadolinium oxide (Gd2O3 hollow microspheres, as formed through a urea-assisted homogenous precipitation process using carbon spheres as a template and a subsequent heat treatment, were characterized by using X-ray diffraction, Fourier transformed infared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Tellet surface area measurement. The results indicate that the final products can be indexed to a cubic Gd2O3 phase with high purity and have a uniform morphology at 500 nm in diameter and 20 nm in shell thickness. The as-synthesized Gd2O3 hollow microspheres exhibited a superior photooxidation activity to that of Gd2O3 powder and an effect similar to P25, significantly broadening the potential of Gd2O3 hollow microspheres for many practical applications.

  12. Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

    KAUST Repository

    Pan, Yue

    2010-03-16

    Nanoparticles that self-assemble on a liquid-liquid interface serve as the building block for making heterodimeric nanostructures. Specifically, hollow iron oxide nanoparticles within hexane form colloidosomes in the aqueous solution of silver nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectrometry, X-ray diffraction, UV-vis spectroscopy, and SQUID were used to characterize the heterodimers. Interestingly, the formation of silver nanoparticles helps the removal of spinglass layer on the hollow iron oxide nanoparticles. This work demonstrates a powerful yet convenient strategy for producing sophisticated, multifunctional nanostructures. © 2010 American Chemical Society.

  13. Hollow Palladium Nanoparticles Facilitated Biodegradation of an Azo Dye by Electrically Active Biofilms

    KAUST Repository

    Kalathil, Shafeer

    2016-08-04

    Dye wastewater severely threatens the environment due to its hazardous and toxic effects. Although many methods are available to degrade dyes, most of them are far from satisfactory. The proposed research provides a green and sustainable approach to degrade an azo dye, methyl orange, by electrically active biofilms (EABs) in the presence of solid and hollow palladium (Pd) nanoparticles. The EABs acted as the electron generator while nanoparticles functioned as the electron carrier agents to enhance degradation rate of the dye by breaking the kinetic barrier. The hollow Pd nanoparticles showed better performance than the solid Pd nanoparticles on the dye degradation, possibly due to high specific surface area and cage effect. The hollow cavities provided by the nanoparticles acted as the reaction centers for the dye degradation.

  14. Improved luminescence behavior of YVO4:Eu3+ hollow microspheres by Ca2+ doping

    Science.gov (United States)

    Jiu, Hongfang; Jiao, Hongqian; Zhang, Lixin; Jia, Wanbao; Huang, Changshui; Chang, Jianxia

    2015-07-01

    The YVO4:Eu3+/Ca2+ hollow microspheres were prepared via a urea-based homogeneous precipitation method in the presence of colloidal melamine formaldehyde resin (MF) microspheres as templates without heat treatment. Photoluminescence characteristics of YVO4:Eu3+ hollow microspheres are studied. X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) measurements were carried out to characterize their structural and luminescent properties. When compared with those of YVO4:Eu3+ hollow microsphere, the emissions of codoped sample with Ca2+ are greatly enhanced. The intensity of charge transfer absorption at 312 nm and its red emission have been greatly increased by codoping the Ca2+ ion into the YVO4:Eu3+ lattice.

  15. The soft-focus lens and Anglo-American pictorialism

    OpenAIRE

    Young, William Russell

    2008-01-01

    Electronic version excludes illustrations for which permission has not been granted by the rights holder The history, practice and aesthetic of the soft focus lens in photography is elucidated and developed from its earliest statements of need to the current time with a particular emphasis on its role in the development of the Pictorialist movement. Using William Crawford's concept of photographic 'syntax', the use of the soft focus lens is explored as an example of how technology shapes s...

  16. Hollow glass fibers in reinforcing glass ionomer cements.

    Science.gov (United States)

    Garoushi, Sufyan; Vallittu, Pekka; Lassila, Lippo

    2017-02-01

    This study investigated the reinforcing effect of hollow and solid discontinuous glass fiber fillers with two different loading fractions on select mechanical properties of conventional and resin modified glass ionomer cements (GICs). Experimental fiber reinforced GIC was prepared by adding discontinuous glass fiber (hollow/solid) of 0.5mm in length to the powder of commercial GICs (GC Fuji IX and II LC) with two different weight ratios (5 and 10wt%) using a high speed mixing machine. Fracture toughness, work of fracture, flexural strength, flexural modulus, compressive strength and diametral tensile strength were determined for each experimental and control material. The specimens (n=7) were wet stored (37°C for one day) before testing. Scanning electron microscopy was used to evaluate the microstructure of the experimental fiber reinforced GICs. Fiber length analysis was carried out to investigate the fiber length distribution of experimental GICs. The results were analyzed statistically using ANOVA followed by Tukey's post hoc test. Level of significance was set at 0.05. An increase in fracture toughness (280 and 200%) and flexural strength (170 and 140%) of hollow discontinuous glass fiber reinforced (10wt%) conventional and resin modified GICs respectively, were achieved compared to unreinforced materials (p0.05) between the fiber reinforced and unreinforced GICs. The use of hollow discontinuous glass fiber fillers with conventional and resin modified GIC matrix is a novel reinforcement. It yielded superior toughening and flexural performance compared to the particulate GICs used. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David)

    2008-11-03

    Hollow micro-nanostructures are of great interest in many current and emerging areas of technology. Perhaps the best-known example of the former is the use of fly-ash hollow particles generated from coal power plants as partial replacement for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic strategies for hollow structures. These strategies are broadly categorized into four themes, which include well-established approaches, such as conventional hard-templating and soft-templating methods, as well as newly emerging methods based on sacrificial templating and template-free synthesis. Success in each has inspired multiple variations that continue to drive the rapid evolution of the field. The Review therefore focuses on the fundamentals of each process, pointing out advantages and disadvantages where appropriate. Strategies for generating more complex hollow structures, such as rattle-type and nonspherical hollow structures, are also discussed. Applications of hollow structures in lithium batteries, catalysis and sensing, and biomedical applications are reviewed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA,.

  18. Sodium Acetate Orientated Hollow/Mesoporous Magnetite Nanoparticles: Facile Synthesis, Characterization and Formation Mechanism

    Directory of Open Access Journals (Sweden)

    Quanguo He

    2018-02-01

    Full Text Available Monodispersed magnetite (Fe3O4 nanospheres with hollow or porous interior structures were synthesized by a facile one-pot solvothermal route. The facile synthetic process was carried out by using iron (III chloride hexahydrate (FeCl3·6H2O as only ferric ion resource, and anhydrous sodium acetate (NaAc as structure-directing agent in an ethylene glycol solution without any templates or surfactants involved. The sizes, morphologies, crystal structures and magnetic properties of hollow Fe3O4 NPs are characterized via Scanning electron microscopy (SEM, Transmission electron microscopy (TEM, X-ray powder diffraction (XRD and Vibrating sample magnetometer (VSM techniques. The influences of reaction time, molar ratio of reactants on the morphologies and magnetic performances are also investigated. The different morphologies of magnetite (Fe3O4 particles were presented with tunable size ranging from 85 to 250 nm and controllable structures including porous and hollow construction by using different amount of anhydrous NaAc. A plausible mechanism based on sodium acetate assistant local Ostwald ripening is proposed for acquiring the tailorable morphology and magnetic performance. Such a design conception of anhydrous NaAc assisted Ostwald ripening applied here is a significant alternative for synthesizing hollow magnetic particles, and it could elucidate some light to understand and construct other novel hollow/mesoporous nanostructures.

  19. Formation of hollow bone-like morphology of calcium carbonate on surfactant/polymer templates

    Science.gov (United States)

    Mantilaka, M. M. M. G. P. G.; Pitawala, H. M. T. G. A.; Rajapakse, R. M. G.; Karunaratne, D. G. G. P.; Upul Wijayantha, K. G.

    2014-04-01

    Novel hollow, bone-like structures of Precipitated Calcium Carbonate (PCC) are fabricated, for the first time, starting from naturally occurring dolomite. The hollow, bone-like structures are prepared by precipitating calcium carbonate on self-assembled poly(acrylic acid)/cetyltrimethylammonium chloride (PAA/CTAC) template. Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Field Emission Scanning Electron Microscopic (FE-SEM) studies reveal that the bone-like structure is composed of Amorphous Calcium Carbonate (ACC) nanoparticles in the center and calcite nanoparticles at the edges. Bone-like PCC particles are in particle length of 2-3 μm and particle width of 1 μm. The internal hollow structures of bone-like particles are observed from TEM images. As identified by FE-SEM images, the bone-like structure has been formed through the crystal growth of initially formed ACC nanoparticles. The ACC particles are stabilized in the center while the calcite crystals have been grown from the ACC toward the edges of the structure to form a bone-like morphology. We also propose a possible mechanism for the formation of hollow bone-like PCC in this study. The fabricated hollow, bone-like PCC has potential applications in the preparation of release systems such as drugs, cosmetics and pigments.

  20. Synergistic effects of hollow structure and surface fluorination on the photocatalytic activity of titania

    Energy Technology Data Exchange (ETDEWEB)

    Lv Kangle, E-mail: lvkangle@mail.scuec.edu.cn [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, South-Central University for Nationalities, Wuhan 430074 (China); State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Yu Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Deng Kejian; Sun Jie; Zhao Yanxi; Du Dongyun; Li Mei [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, South-Central University for Nationalities, Wuhan 430074 (China)

    2010-01-15

    To study the synergistic effects of hollow structure and surface fluorination on the photoactivity of TiO{sub 2}, TiO{sub 2} hollow microspheres were synthesized by a hydrolysis-precipitate method using sulfonated polystyrene (PS) as templates and tetrabutylorthotitanate (TBOT) as precursor, and then calcined at 500 {sup o}C for 2 h. The calcined samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N{sub 2} sorption. Photocatalytic activity was evaluated using reactive brilliant red X3B, an anionic organic dye, as a model pollutant in water. The results show that the photocatalytic activity of TiO{sub 2} hollow microspheres is significantly higher than that of TiO{sub 2} nanoparticles prepared in the same experimental conditions. At pH 7 and 3, the apparent rate constants of the former exceed that of the latter by a factor of 3.38 and 3.15, respectively. After surface fluorination at pH 3, the photoactivity of hollow microspheres and nanoparticles further increases for another 1.61 and 2.19 times, respectively. The synergistic effect of surface fluorination and hollow structure can also be used to prepare other highly efficient photocatalyst.

  1. The facile fabrication of hollow Cu{sub 2}O nanoparticles induced by the kirkendall effect on Cu@Ag core-shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Ying; Kim, Sang Ho; Piao, Longhai [Dept. of Chemistry, Kongju National University, Kongju (Korea, Republic of); Kang, Hyun Suk; Lee, Byung Cheol [Radiation Integrated System Research Division, Korea Atomic Energy Research Institute (KAERI), Daejeon (Korea, Republic of); Lim, Young S. [Green Ceramics Division, Korea Institute of Ceramic Engineering and Technology, Seoul (Korea, Republic of)

    2015-08-15

    Many studies have been recently performed on hollow inorganic nanoparticles (NPs) because of their unique structural superiority and special physico-chemical properties, such as their low density, high specific surface area, and the effect of their void space. Hollow inorganic NPs may result in tremendous improvements in catalysts, magnetics, sensors, microelectronics, chemical reactors, drug delivery, light-weight structural materials, and so on. Because of these comprehensive applications, various methods have been used for fabricating hollow inorganic NPs, including the template method, interface-mineralizing, Ostwald ripening, galvanic replacement, and the Kirkendall effect of their void space. The hollow NPs obtained by heating at 150 .deg. C for 30 min were characterized using high-resolution transmission electron microscopy (HRTEM) to thoroughly investigate their lattice structure and surface topography. Figure 3(a) and (b) separately shows the HRTEM and the selected area electron diffraction (Sated) images of the hollow NPs thus obtained.

  2. Hollow Core, Whispering Gallery Resonator Sensors

    CERN Document Server

    Ward, Jonathan M; Chormaic, Síle Nic

    2014-01-01

    A review of hollow core whispering gallery resonators (WGRs)is given. After a short introduction to the topic of whispering gallery resonators we provide a description of whispering gallery modes in hollow or liquid core WGRs. Next, whispering gallery mode (WGM) sensing mechanisms are outlined and some fabrication methods for microbubbles, microcapillaries and other tubular WGM devices are discussed. We then focus on the most common applications of hollow core WGRs, namely refractive index and temperature sensing, gas sensing, force sensing, biosensing, and lasing. The review highlights some of the key papers in this field and gives the reader a general overview of the current state-of-the-art.

  3. [Correct contact lens hygiene].

    Science.gov (United States)

    Blümle, S; Kaercher, T; Khaireddin, R

    2013-06-01

    Although contact lenses have long been established in ophthalmology, practical aspects of handling contact lenses is becoming increasingly less important in the clinical training as specialist for ophthalmology. Simultaneously, for many reasons injuries due to wearing contact lenses are increasing. In order to correct this discrepancy, information on contact lenses and practical experience with them must be substantially increased from a medical perspective. This review article deals with the most important aspects for prevention of complications, i.e. contact lens hygiene.

  4. Synthesis and electrophoretic deposition of hollow-TiO{sub 2} nanoparticles for dye sensitized solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Chava, Rama Krishna; Raj, Sudarsan; Yu, Yeon-Tae, E-mail: yeontae@jbnu.ac.kr

    2016-07-05

    Hollow TiO{sub 2} nanoparticles having ∼200 nm size are successfully prepared via selective etching of Au@TiO{sub 2} core shell nanoparticles which were synthesized by microwave hydrothermal growth. Electrophoretic deposition was successfully applied to make hollow TiO{sub 2} nanoparticles scattering layer for dye-sensitized solar cells (DSSCs) applications. The surface morphology and roughness features of deposited hollow TiO{sub 2} nanoparticles films are studied by field emission scanning electron microscope and atomic force microscope techniques respectively. The light scattering property of H–TiO{sub 2} makes it a promising candidate for use as the scattering layer in dye sensitized solar cells. Enhanced J{sub SC} values for the H–TiO{sub 2} based DSSCs were attributed to larger dye adsorption and stronger light scattering compared to the commercial TiO{sub 2} nanoparticle with a crystalline size of 20 nm. - Highlights: • Hollow TiO{sub 2} are produced by KCN etching of Au@TiO{sub 2} core–shell NPs. • EPD was successfully applied to make hollow TiO{sub 2} NPs film. • Compact, crack free and uniform hollow TiO{sub 2} NPs film was obtained by EPD. • Scattering layer of hollow TiO{sub 2} NPs was successfully introduced in DSS Cell.

  5. Prolonging contact lens wear and making contact lens wear safer.

    Science.gov (United States)

    Foulks, Gary N

    2006-02-01

    To summarize the present status of safety and efficacy of contact lens wear. Literature review. Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses. Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses. The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.

  6. Retrofitting of bridge hollow piers with CFRP

    OpenAIRE

    Pedro Delgado; Patrício Rocha; João Pedrosa; António Arêde; Nelson Vila Pouca; Miguel Santos; Aníbal Costa; Raimundo Delgado

    2007-01-01

    Hollow bridge piers generally have large section dimensions, with reinforcement barsspread along both wall faces. Unlike common solid section columns, quite often the shear effect hasgreat importance on the pier behavior. Therefore, it is of particular relevance that special attention isgiven to this issue when the assessment and retrofit of RC hollow section piers is envisaged. Representativeof typical bridge construction, RC piers were tested at LESE ¿ the Laboratory of Earthquakeand Struct...

  7. Titania coated hollow glass microspheres for environmental applications

    Science.gov (United States)

    Koopman, Mark C.

    The potential applicability of titania coated hollow glass microspheres (HGMs) to the photocatalytic degradation of microbiological and organic chemical water pollutants could have dramatic positive effects on improving the quality of industrial wastewaters that empty into rivers and streams, as well as potential use in economically improving the quality of drinking water. Heterogeneous photocatalysis using titania has been extensively studied since the 1990's because of its non-toxic nature, its high quantum yield of electrons and photo-holes, and its ability to use ambient solar radiation as a power source. Although titania embodies extraordinarily attractive properties for a range of environmental applications, a viable substrate or method of using the material effectively has not been recognized. HGMs are particularly attractive as a support for titania because of their low density and high surface area to volume ratio, but details of how they react to imposed loading, wear, and impact have not been addressed, nor have materials engineering analyses that could maximize their utility been made. In this study we have examined the microstructure, morphology and micro-compression properties of two types of titania coated hollow microspheres, a commercially produced HGM and cenospheres, a derivative of fly ash. Comparisons of uncoated and titania coated hollow microspheres showed improved failure loads and facture energies for the titania coated materials over the uncoated hollow microspheres. Also, the relationship between failure load and hollow microsphere diameter was characterized and the function employed to explain part of the gain in average failure load for the HGMs. Microscopic examination of titania coated HGMs that were subjected to various turbulent conditions, as well as intentional fracture, indicated good interfacial integrity, which supports the viability of both types of HGMs for potential applications. The photocatalytic reactivity of the titania

  8. Etched glass self-assembles into micron-size hollow platonic solids

    KAUST Repository

    Boukhalfa, Sofiane

    2012-10-03

    The interaction between the spreading of a hydrofluoric acid-based drop on a glass surface and its etching rate gives rise to hollow crystals of various shapes, including cubes, triangles, and icosahedra. These geometries are dependent on their position with respect to the contact line, where a rim forms by agglutination, similar to the formation of a coffee stain. Atomic force microscopy indentation and transmission electron microscopy observations revealed that these crystals are hollow ammonium-fluosilicate-based cryptohalite shells. © 2012 American Chemical Society.

  9. Facile fabrication of AgCl@polypyrrole-chitosan core-shell nanoparticles and polymeric hollow nanospheres.

    Science.gov (United States)

    Cheng, Daming; Xia, Haibing; Chan, Hardy Sze On

    2004-11-09

    A one-step sequential method for preparing AgCl@polypyrrole-chitosan core-shell nanoparticles and subsequently the formation of polypyrrole-chitosan hollow nanospheres is reported. The formation of the core and the shell is performed in one reaction medium almost simultaneously. Transmission electron microscopy (TEM) images show the presence of core-shell nanoparticles and hollow nanospheres. Ultraviolet-visible (UV-vis) studies reveal that AgCl was formed first followed by polypyrrole. X-ray diffration (XRD) and UV-vis studies show that AgCl was present in the core-shell nanoparticles and could be removed completely from the core.

  10. Interaction of slow and highly charged ions with surfaces: formation of hollow atoms

    Energy Technology Data Exchange (ETDEWEB)

    Stolterfoht, N.; Grether, M.; Spieler, A.; Niemann, D. [Hahn-Meitner Institut, Berlin (Germany). Bereich Festkoerperphysik; Arnau, A.

    1997-03-01

    The method of Auger spectroscopy was used to study the interaction of highly charged ions with Al and C surfaces. The formation of hollow Ne atoms in the first surface layers was evaluated by means of a Density Functional theory including non-linear screening effects. The time-dependent filling of the hollow atom was determined from a cascade model yielding information about the structure of the K-Auger spectra. Variation of total intensities of the L- and K-Auger peaks were interpreted by the cascade model in terms of attenuation effects on the electrons in the solid. (author)

  11. Plasma lens experiments at the Final Focus Test Beam

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, B. [California Univ., Los Angeles, CA (United States)]|[Lawrence Berkeley Lab., CA (United States); Chattopadhyay, S. [Lawrence Berkeley Lab., CA (United States); Chen, P. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)] [and others

    1993-04-01

    We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam ionization of a working gas. At an increased bunch population of 2.5 {times} 10{sup 10}, tunneling ionization of a gas target by an electron beam -- an effect which has never been observed before -- should be significant. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.

  12. A templated method to Bi2WO6 hollow microspheres and their conversion to double-shell Bi2O3/Bi2WO6 hollow microspheres with improved photocatalytic performance.

    Science.gov (United States)

    Li, Xiaona; Huang, Renkun; Hu, Yanhua; Chen, Yongjuan; Liu, Wenjun; Yuan, Rusheng; Li, Zhaohui

    2012-06-04

    Bi(2)WO(6) hollow microspheres with dimension of ca. 1.5 μm were synthesized via a hydrothermal method using polystyrene particles as the template. The as-prepared Bi(2)WO(6) hollow microspheres can be further transformed to double-shell Bi(2)O(3)/Bi(2)WO(6) hollow microspheres. The samples were fully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, N(2)-sorption Brunauer-Emmett-Teller surface area, UV-vis diffuse-reflectance spectroscopy, and X-ray photoelectron spectroscopy. The as-formed double-shell Bi(2)O(3)/Bi(2)WO(6) hollow microspheres exhibit enhanced photocatalytic activity due to the hollow nature and formation of the p-n junction between p-type Bi(2)O(3) and n-type Bi(2)WO(6). The study provides a general and effective method in the fabrication of composition and dimension-tunable composite hollow microspheres with sound heterojunctions that may show a variety of applications.

  13. Lens cytoskeleton and after-cataract.

    Science.gov (United States)

    Rafferty, N S; Rafferty, K A

    1992-01-01

    Lens epithelial and other ocular cells contain complex arrays of actin filaments which might be expected to allow them to migrate following injury: specifically into the capsular sac in cases of extracapsular cataract extraction or traumatic cataract. To test the possibility, a culture system was developed using a melanotic strain of mice, in which migrating cells are often 'marked' by melanosomes. Injured lenses were cultured on permeable membranes in contact with nutrient medium, and surrounded by iridial tract fragments. After study by light and electron microscopy, it was established that both pigmented and unpigmented cells migrated from the surrounding explants, apparently along the substrate meniscus, to the outside of the lens capsule and then through the wound to the capsule interior. This study suggests a source of cells in development of after-cataract syndrome.

  14. Nb{sub 2}O{sub 5} hollow nanospheres as anode material for enhanced performance in lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sasidharan, Manickam [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan); Gunawardhana, Nanda [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Yoshio, Masaki, E-mail: yoshio@cc.saga-u.ac.jp [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Nakashima, Kenichi, E-mail: nakashik@cc.saga-u.ac.jp [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

    2012-09-15

    Graphical abstract: Nb{sub 2}O{sub 5} hollow nanosphere constructed electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles and maintains structural integrity and excellent cycling stability. Highlights: ► Nb{sub 2}O{sub 5} hollow nanospheres synthesis was synthesized by soft-template. ► Nb{sub 2}O{sub 5} hollow nanospheres were investigated as anode material in Li-ion battery. ► Nanostructured electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles. ► The electrode maintains the structural integrity and excellent cycling stability. ► Nanosized shell domain facilitates fast lithium intercalation/deintercalation. -- Abstract: Nb{sub 2}O{sub 5} hollow nanospheres of average diameter ca. ∼29 nm and hollow cavity size ca. 17 nm were synthesized using polymeric micelles with core–shell–corona architecture under mild conditions. The hollow particles were thoroughly characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal (TG/DTA) and nitrogen adsorption analyses. Thus obtained Nb{sub 2}O{sub 5} hollow nanospheres were investigated as anode materials for lithium ion rechargeable batteries for the first time. The nanostructured electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles of charge/discharge at a rate of 0.5 C. More importantly, the hollow particles based electrodes maintains the structural integrity and excellent cycling stability even after exposing to high current density 6.25 A g{sup −1}. The enhanced electrochemical behavior is ascribed to hollow cavity coupled with nanosized Nb{sub 2}O{sub 5} shell domain that facilitates fast lithium intercalation/deintercalation kinetics.

  15. Contact lens correction of presbyopia.

    Science.gov (United States)

    Morgan, Philip B; Efron, Nathan

    2009-08-01

    The ageing population highlights the need to provide effective optical solutions for presbyopic contact lens wearers. However, data gathered from annual contact lens fitting surveys demonstrate that fewer than 40% of contact lens wearers over 45 years of age (virtually all of whom can be presumed to suffer a partial or complete loss of accommodation) are prescribed a presbyopic correction. Furthermore, monovision is prescribed as frequently as multifocal lenses. These observations suggest that an optimal solution to the contact lens correction of presbyopia remains elusive.

  16. Synthesis of Hollow CdS-TiO2 Microspheres with Enhanced Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Yuning Huo

    2012-01-01

    Full Text Available CdS-TiO2 composite photocatalyst in the shape of hollow microsphere was successfully synthesized via the hard-template preparation with polystyrene microspheres followed by ion-exchange approach. The hollow CdS-TiO2 microspheres significantly extended the light adsorption into visible light region, comparing to TiO2 microspheres. It led to much higher photocatalytic activities of hollow CdS-TiO2 microspheres than that of TiO2 during the photodegradation of rhodamine B under visible light irradiations. Furthermore, the well-remained hollow structure could achieve light multireflection within the interior cavities and the separation of photo-induced electrons and holes is efficient in CdS-TiO2, which were facilitated to improving the photoactivity.

  17. A template-free method for stable CuO hollow microspheres fabricated from a metal organic framework (HKUST-1)

    Science.gov (United States)

    Zhang, Suoying; Liu, Hong; Liu, Pengfei; Yang, Zhuhong; Feng, Xin; Huo, Fengwei; Lu, Xiaohua

    2015-05-01

    Uniform CuO hollow microspheres were successfully achieved from a non-uniform metal organic framework by using a template-free method. The process mechanism has been revealed to be spherical aggregation and Ostwald ripening. When tested in CO oxidation and heat treatment, these assembled microspheres exhibited an excellent catalytic performance and show a much better stability than the inherited hollow structure from MOFs.Uniform CuO hollow microspheres were successfully achieved from a non-uniform metal organic framework by using a template-free method. The process mechanism has been revealed to be spherical aggregation and Ostwald ripening. When tested in CO oxidation and heat treatment, these assembled microspheres exhibited an excellent catalytic performance and show a much better stability than the inherited hollow structure from MOFs. Electronic supplementary information (ESI) available: The experiment details, auxiliary FESEM, XRD, BET and TG results of synthesized products. See DOI: 10.1039/c5nr01443c

  18. Up-conversion in rare earth-doped silica hollow spheres

    Science.gov (United States)

    Fortes, Luís M.; Li, Yigang; Réfega, Ricardo; Clara Gonçalves, M.

    2012-06-01

    In the present work, Er/Yb co-doped silica hollow spheres are prepared in a two-step process. In a first step, polystyrene-core is silica coated in situ by a modified Stöber sol-gel method and in the second one, the sacrificial polystyrene core is thermally removed. The core-shell and the hollow spheres are characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). PL measurements show up-conversion phenomena upon excitation at 975 nm, through the emission of blue (˜490 nm), green (˜523 nm and ˜536 nm) and red (˜655 nm) light. The up-conversion phenomena are discussed and modelled. The developed model explains the up-conversion phenomena of Er/Yb co-doped silica hollow spheres, with special agreement for high Yb/Er ratio.

  19. Preparation and evaluation of glyceryl monooleate-coated hollow-bioadhesive microspheres for gastroretentive drug delivery.

    Science.gov (United States)

    Liu, Yuanfen; Zhang, Jianjun; Gao, Yuan; Zhu, Jiabi

    2011-07-15

    The purpose of this study was to produce hollow and bioadhesive microspheres to lengthen drug retention time in the stomach. In these microspheres, ethylcellulose was used as the matrix, Eudragit EPO was employed to modulate the release rate, and glyceryl monooleate (GMO) was the bioadhesive polymer in situ. The morphological characteristics of the microspheres were defined using scanning electron microscopy. The in vitro release test showed that the release rate of drug from the microspheres was pH-dependent, and was not influenced by the GMO coating film. The prepared microspheres demonstrated strong mucoadhesive properties with good buoyancy both in vitro and in vivo. Pharmacokinetic analysis indicated that the elimination half-life time of the hollow-bioadhesive microspheres was prolonged, and that the elimination rate was decreased. In conclusion, the hollow-bioadhesive synergic drug delivery system may be advantageous in the treatment of stomach diseases. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. The 2014 IODC lens design problem: the Cinderella lens

    Science.gov (United States)

    Juergens, Richard C.

    2014-12-01

    The lens design problem for the 2014 IODC is to design a 100 mm focal length lens in which all the components of the lens can be manufactured from ten Schott N-BK7 lens blanks 100 mm in diameter x 30 mm thick. The lens is used monochromatically at 587.56 nm. The goal of the problem is to maximize the product of the entrance pupil diameter and the semi-field of view while holding the RMS wavefront error to <= 0.070 wave within the field of view. There were 45 entries from 13 different countries. Four different commercial lens design programs were used, along with six custom, in-house programs. The number of lens elements in the entries ranged from 10 to 52. The winning entry from Jon Ehrmann had 25 lens elements, and had an entrance pupil diameter of 33.9 mm and a semi-field of view of 62.5° for a merit function product of 2,119.

  1. Compliance among soft contact lens wearers.

    OpenAIRE

    Kuzman, Tomislav; Barišić Kutija, Marija; Masnec, Sanja; Jandroković, Sonja; Mrazovac, Danijela; Jurišić, Darija; Škegro, Ivan; Kalauz, Miro; Kordić, Rajko

    2014-01-01

    Contact lens compliance is proven to be crucial for preventing lens wear-related complications because of the interdependence of the steps in lens care regime and their influence on lens system microbial contamination. Awareness of the patients' lens handling compliance as well as correct recognition of non-compliant behaviours is the basis for creating more targeted strategies for patient education. The aim of this study was to investigate compliance among soft contact lens (SCL) wearers in ...

  2. Magnetic and optical properties of electrospun hollow nanofibers of SnO2 doped with Ce-ion

    Science.gov (United States)

    Mohanapriya, P.; Pradeepkumar, R.; Victor Jaya, N.; Natarajan, T. S.

    2014-07-01

    Cerium doped SnO2 hollow nanofibers were synthesized by electrospinning. High resolution scanning electron microscope (HRSEM) and transmission electron microscopy (TEM) analysis showed hollow nanofibers with diameters around ˜200 nm. The optimized substitution of Ce ion into SnO2 lattices happened above 6 mol. % doping as confirmed by Powder X-ray diffraction (XRD) studies. Optical band gap was decreased by the doping confirming the direct energy transfer between f-electrons of rare earth ion and the SnO2 conduction or valence band. The compound also exhibited room temperature ferromagnetism with the saturation magnetization of 19 × 10-5 emu/g at 6 mol. %. This study demonstrates the Ce doped SnO2 hollow nanofibers for applications in magneto-optoelectronic devices.

  3. Dual focus polarisation splitting lens.

    Science.gov (United States)

    Moseley, Paul; Savini, Giorgio; Zhang, Jin; Ade, Peter

    2017-10-16

    We have successfully designed and measured a unique polarisation splitting lens which focuses the orthogonal linear polarisations side-by-side in the lens focal plane. This concept can find application in situations where there is limited space for the beam splitters and focusing optics that are required for incoherent detectors.

  4. Focusing on Contact Lens Safety

    Science.gov (United States)

    ... these solutions require special care. Always remove contact lenses before swimming. Never reuse any lens solution. Always discard all of the used solution after each use, and add fresh solution to your lens case. Do not expose your contacts to any water (which includes lake, pond, and ocean water as ...

  5. Criteria for choosing lens implants.

    Science.gov (United States)

    Rado, G; Filip, M; Costea, J; Niculescu, C; Pienaru, M

    1998-01-01

    Choosing the proper artificial lens can be a problem, especially for the young surgeons, considering the fact that the "market" is so rich in possibilities. The present paper analyses the lens according to their dimension, form and material, in a perspective based on personal experience.

  6. Lens epithelial cell layer formation related to hydrogel foldable intraocular lenses

    NARCIS (Netherlands)

    Koch, M.W.; Kalicharan, D; van der Want, JJL

    1999-01-01

    Purpose: To determine the incidence of postoperative lens epithelial cel (LEC) layer formation anterior to the Hydroview hydrogel foldable intraocular lens (IOL), the effect on vision, and the appearance under scanning electron microscopy (SEM). Setting: Eye Unit of district general hospital,

  7. Contact and noncontact laser preparation of hard dental tissues by Er:YAG laser radiation delivered by hollow glass waveguide or articulated arm

    Science.gov (United States)

    Dostalova, Tatjana; Jelinkova, Helena; Miyagi, Mitsunobu; Nemec, Michal; Hamal, Karel; Krejsa, Otakar

    1999-05-01

    The differences between a contact and non-contact Er:YAG laser hard dental tissue preparation were verified. The influence of laser energy and number of pulses on a profile and depth of a drilled cavity was investigated. The delivery systems used were an articulated arm and a cyclic olefin polymer-coated silver hollow glass waveguide with or without a special sapphire tip. In the case of the non-contact preparation, the laser radiation was directed onto the dental tissue by focusing optics (CaF2 lens) together with the cooling water spray in order to ensure that the tissues will not be burned. The water spray was also used during the preparation when the waveguide with a sapphire tip was used to deliver the radiation. For the evaluation of shapes, depth and profiles of the prepared cavities the metallographic microscope, photographs from the light microscope and scanning electron microsec were used. From the result it follows that great differences exist in the laser speed, value of energy, the profile, and depth of the cavities prepared by the contact and non-contact preparation. In the case of contact ablation the procedure is quicker, the energy fluence needed is lower and more precise cavities with larger diameters are produced.

  8. A 13000-hour test of a mercury hollow cathode

    Science.gov (United States)

    Rawlin, V. K.

    1973-01-01

    A mercury-fed hollow cathode was tested for 12,979 hours in a bell jar at SERT 2 neutralizer operating conditions. The net electron current drawn to a collector was 0.25 ampere at average collector voltages between 21.8 and 36.7 volts. The mercury flow rate was varied from 5.6 to 30.8 equivalent milliamperes to give stable operation at the desired electrode voltages and currents. Variations with time in the neutralizer discharge characteristics were observed and hypothesized to be related to changes in the cathode orifice dimensions and the availability of electron emissive material. A facility failure caused abnormal test conditions for the last 876 hours and led to the cathode heater failure which concluded the test.

  9. Method for the production of fabricated hollow microspheroids

    Energy Technology Data Exchange (ETDEWEB)

    Wickramanayake, Shan; Luebke, David R.

    2015-06-09

    The method relates to the fabrication of a polymer microspheres comprised of an asymmetric layer surrounding a hollow interior. The fabricated hollow microsphere is generated from a nascent hollow microsphere comprised of an inner core of core fluid surrounded by a dope layer of polymer dope, where the thickness of the dope layer is at least 10% and less than 50% of the diameter of the inner core. The nascent hollow microsphere is exposed to a gaseous environment, generating a vitrified hollow microsphere, which is subsequently immersed in a coagulation bath. Solvent exchange produces a fabricated hollow microsphere comprised of a densified outer skin surrounding a macroporous inner layer, which surrounds a hollow interior. In an embodiment, the polymer is a polyimide or a polyamide-imide, and the non-solvent in the core fluid and the coagulation bath is water. The fabricated hollow microspheres are particularly suited as solvent supports for gas separation processes.

  10. Process for manufacturing hollow fused-silica insulator cylinder

    Science.gov (United States)

    Sampayan, Stephen E.; Krogh, Michael L.; Davis, Steven C.; Decker, Derek E.; Rosenblum, Ben Z.; Sanders, David M.; Elizondo-Decanini, Juan M.

    2001-01-01

    A method for building hollow insulator cylinders that can have each end closed off with a high voltage electrode to contain a vacuum. A series of fused-silica round flat plates are fabricated with a large central hole and equal inside and outside diameters. The thickness of each is related to the electron orbit diameter of electrons that escape the material surface, loop, and return back. Electrons in such electron orbits can support avalanche mechanisms that result in surface flashover. For example, the thickness of each of the fused-silica round flat plates is about 0.5 millimeter. In general, the thinner the better. Metal, such as gold, is deposited onto each top and bottom surface of the fused-silica round flat plates using chemical vapor deposition (CVD). Eutectic metals can also be used with one alloy constituent on the top and the other on the bottom. The CVD, or a separate diffusion step, can be used to defuse the deposited metal deep into each fused-silica round flat plate. The conductive layer may also be applied by ion implantation or gas diffusion into the surface. The resulting structure may then be fused together into an insulator stack. The coated plates are aligned and then stacked, head-to-toe. Such stack is heated and pressed together enough to cause the metal interfaces to fuse, e.g., by welding, brazing or eutectic bonding. Such fusing is preferably complete enough to maintain a vacuum within the inner core of the assembled structure. A hollow cylinder structure results that can be used as a core liner in a dielectric wall accelerator and as a vacuum envelope for a vacuum tube device where the voltage gradients exceed 150 kV/cm.

  11. Wedged multilayer Laue lens

    Science.gov (United States)

    Conley, Ray; Liu, Chian; Qian, Jun; Kewish, Cameron M.; Macrander, Albert T.; Yan, Hanfei; Kang, Hyon Chol; Maser, Jörg; Stephenson, G. Brian

    2008-05-01

    A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures.

  12. Zinc oxide hollow micro spheres and nano rods: Synthesis and applications in gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, Saba, E-mail: saba_hrb@yahoo.com [Department of Chemistry, University of Sargodha, Sargodha 40100 (Pakistan); Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Institute of Advanced Marine Materials, Harbin Engineering University, 150001 (China); Janjua, Muhammad Ramzan Saeed Ashraf, E-mail: Janjua@uos.edu.pk [Department of Chemistry, University of Sargodha, Sargodha 40100 (Pakistan); Ahmad, Tauqeer; Mehmood, Tahir [Department of Chemistry, University of Sargodha, Sargodha 40100 (Pakistan); Li, Songnan [Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Jing, Xiaoyan [Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Institute of Advanced Marine Materials, Harbin Engineering University, 150001 (China)

    2014-09-15

    Zinc oxide nano rods and micro hollow spheres are successfully fabricated by adopting a simple solvo-thermal approach without employing any surfactant/template by keeping heating time as variable. The prepared products are characterized by using different instruments such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In order to investigate the morphological dependence on the reaction time, analogous experiments with various reaction times are carried out. Depending upon heating time, different morphological forms have been identified such as hollow microsphere (4 μm to 5 μm) and nano rods with an average diameter of approximately 100 nm. The fabricated materials are also tested for ethanol gas sensor applications and zinc oxide hollow microsphere proven to be an efficient gas sensing materials. Nitrogen adsorption–desorption measurement was performed to understand better performance of zinc oxide micro hollow spheres as effective ethanol gas sensing material. - Graphical abstract: Graphical abstract is represented by zinc oxide sphere (prepared by simple solvothermal approach), its XRD pattern(characterization) and finally its application in gas sensing. - Highlights: • Zinc oxide spheres were prepared by using solvothermal method. • Detailed description of the morphology of microspheres assembled by nano rods. • Formation mechanism of zinc oxide spheres assembled by nano rods. • Zinc oxide spheres and nano rods displayed very good gas sensing ability.

  13. Hollow metal nanostructures for enhanced plasmonics: synthesis, local plasmonic properties and applications

    Science.gov (United States)

    Genç, Aziz; Patarroyo, Javier; Sancho-Parramon, Jordi; Bastús, Neus G.; Puntes, Victor; Arbiol, Jordi

    2017-01-01

    Metallic nanostructures have received great attention due to their ability to generate surface plasmon resonances, which are collective oscillations of conduction electrons of a material excited by an electromagnetic wave. Plasmonic metal nanostructures are able to localize and manipulate the light at the nanoscale and, therefore, are attractive building blocks for various emerging applications. In particular, hollow nanostructures are promising plasmonic materials as cavities are known to have better plasmonic properties than their solid counterparts thanks to the plasmon hybridization mechanism. The hybridization of the plasmons results in the enhancement of the plasmon fields along with more homogeneous distribution as well as the reduction of localized surface plasmon resonance (LSPR) quenching due to absorption. In this review, we summarize the efforts on the synthesis of hollow metal nanostructures with an emphasis on the galvanic replacement reaction. In the second part of this review, we discuss the advancements on the characterization of plasmonic properties of hollow nanostructures, covering the single nanoparticle experiments, nanoscale characterization via electron energy-loss spectroscopy and modeling and simulation studies. Examples of the applications, i.e. sensing, surface enhanced Raman spectroscopy, photothermal ablation therapy of cancer, drug delivery or catalysis among others, where hollow nanostructures perform better than their solid counterparts, are also evaluated.

  14. Plasma characteristics in the discharge region of a 20 A emission current hollow cathode

    Science.gov (United States)

    Mingming, SUN; Tianping, ZHANG; Xiaodong, WEN; Weilong, GUO; Jiayao, SONG

    2018-02-01

    Numerical calculation and fluid simulation methods were used to obtain the plasma characteristics in the discharge region of the LIPS-300 ion thruster’s 20 A emission current hollow cathode and to verify the structural design of the emitter. The results of the two methods indicated that the highest plasma density and electron temperature, which improved significantly in the orifice region, were located in the discharge region of the hollow cathode. The magnitude of plasma density was about 1021 m‑3 in the emitter and orifice regions, as obtained by numerical calculations, but decreased exponentially in the plume region with the distance from the orifice exit. Meanwhile, compared to the emitter region, the electron temperature and current improved by about 36% in the orifice region. The hollow cathode performance test results were in good agreement with the numerical calculation results, which proved that that the structural design of the emitter and the orifice met the requirements of a 20 A emission current. The numerical calculation method can be used to estimate plasma characteristics in the preliminary design stage of hollow cathodes.

  15. Hollow metal nanostructures for enhanced plasmonics: synthesis, local plasmonic properties and applications

    Directory of Open Access Journals (Sweden)

    Genç Aziz

    2016-09-01

    Full Text Available Metallic nanostructures have received great attention due to their ability to generate surface plasmon resonances, which are collective oscillations of conduction electrons of a material excited by an electromagnetic wave. Plasmonic metal nanostructures are able to localize and manipulate the light at the nanoscale and, therefore, are attractive building blocks for various emerging applications. In particular, hollow nanostructures are promising plasmonic materials as cavities are known to have better plasmonic properties than their solid counterparts thanks to the plasmon hybridization mechanism. The hybridization of the plasmons results in the enhancement of the plasmon fields along with more homogeneous distribution as well as the reduction of localized surface plasmon resonance (LSPR quenching due to absorption. In this review, we summarize the efforts on the synthesis of hollow metal nanostructures with an emphasis on the galvanic replacement reaction. In the second part of this review, we discuss the advancements on the characterization of plasmonic properties of hollow nanostructures, covering the single nanoparticle experiments, nanoscale characterization via electron energy-loss spectroscopy and modeling and simulation studies. Examples of the applications, i.e. sensing, surface enhanced Raman spectroscopy, photothermal ablation therapy of cancer, drug delivery or catalysis among others, where hollow nanostructures perform better than their solid counterparts, are also evaluated.

  16. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  17. Dynamics of hollow atom formation in intense x-ray pulses probed by partial covariance mapping.

    Science.gov (United States)

    Frasinski, L J; Zhaunerchyk, V; Mucke, M; Squibb, R J; Siano, M; Eland, J H D; Linusson, P; v d Meulen, P; Salén, P; Thomas, R D; Larsson, M; Foucar, L; Ullrich, J; Motomura, K; Mondal, S; Ueda, K; Osipov, T; Fang, L; Murphy, B F; Berrah, N; Bostedt, C; Bozek, J D; Schorb, S; Messerschmidt, M; Glownia, J M; Cryan, J P; Coffee, R N; Takahashi, O; Wada, S; Piancastelli, M N; Richter, R; Prince, K C; Feifel, R

    2013-08-16

    When exposed to ultraintense x-radiation sources such as free electron lasers (FELs) the innermost electronic shell can efficiently be emptied, creating a transient hollow atom or molecule. Understanding the femtosecond dynamics of such systems is fundamental to achieving atomic resolution in flash diffraction imaging of noncrystallized complex biological samples. We demonstrate the capacity of a correlation method called "partial covariance mapping" to probe the electron dynamics of neon atoms exposed to intense 8 fs pulses of 1062 eV photons. A complete picture of ionization processes competing in hollow atom formation and decay is visualized with unprecedented ease and the map reveals hitherto unobserved nonlinear sequences of photoionization and Auger events. The technique is particularly well suited to the high counting rate inherent in FEL experiments.

  18. Adiabatic Rearrangement of Hollow PV Towers

    Directory of Open Access Journals (Sweden)

    Eric A Hendricks

    2010-10-01

    Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane

  19. Potential of Hollow Glass Microsphere as Cement Replacement for Lightweight Foam Concrete on Thermal Insulation Performance

    Directory of Open Access Journals (Sweden)

    Shahidan Shahiron

    2017-01-01

    Full Text Available Global warming can be defined as a gradual increase in the overall temperature of the earth’s atmosphere. A lot of research work has been carried out to reduce that heat inside the residence such as the used of low density products which can reduce the self-weight, foundation size and construction costs. Foamed concrete it possesses high flow ability, low self-weight, minimal consumption of aggregate, controlled low strength and excellent thermal insulation properties. This study investigate the characteristics of lightweight foamed concrete where Portland cement (OPC was replaced by hollow glass microsphere (HGMs at 0%, 3%, 6%, 9% by weight. The density of wet concrete is 1000 kg/m3 were tested with a ratio of 0.55 for all water binder mixture. Lightweight foamed concrete hollow glass microsphere (HGMs produced were cured by air curing and water curing in tank for 7, 14 and 28 days. A total of 52 concrete cubes of size 100mm × 100mm × 100mm and 215mm × 102.5mm × 65mm were produced. Furthermore, Scanning Electron Microscope (SEM and X-ray fluorescence (XRF were carried out to study the chemical composition and physical properties of crystalline materials in hollow glass microspheres. The experiments involved in this study are compression strength, water absorption test, density and thermal insulation test. The results show that the compressive strength of foamed concrete has reached the highest in 3% of hollow glass microsphere with less water absorption and less of thermal insulation. As a conclusion, the quantity of hollow glass microsphere plays an important role in determining the strength and water absorption and also thermal insulation in foamed concrete and 3% hollow glass microspheres as a replacement for Portland cement (OPC showed an optimum value in this study as it presents a significant effect than other percentage.

  20. Hollow mesoporous raspberry-like colloids with removable caps as photoresponsive nanocontainers

    Science.gov (United States)

    Hu, Chi; West, Kevin R.; Scherman, Oren A.

    2016-04-01

    The fabrication, characterisation and controlled cargo release of hollow mesoporous raspberry-like colloids (HMRCs), which are assembled by utilising host-guest complexation of cucurbit[8]uril (CB[8]) are described. CB[8] is employed as a supramolecular linker to `stick' the viologen functionalised paramagnetic iron oxide nanoparticles onto an azobenzene functionalised hollow mesoporous silica core. The formed HMRCs are photoresponsive and can be reversibly disassembled upon light irradiation, endowing them with an ability to release loaded cargo under photocontrol. While the assembled HMRCs retain cargo inside their cavity, disassembled particles with their iron oxide nanoparticle `caps' removed will release the loaded cargo through the mesoporous shell of the hollow silica colloids. A model system using a boronic acid derivative as the cargo in the HMRCs and Alizarin Red salt as a sensor for the released boronic acid is demonstrated.The fabrication, characterisation and controlled cargo release of hollow mesoporous raspberry-like colloids (HMRCs), which are assembled by utilising host-guest complexation of cucurbit[8]uril (CB[8]) are described. CB[8] is employed as a supramolecular linker to `stick' the viologen functionalised paramagnetic iron oxide nanoparticles onto an azobenzene functionalised hollow mesoporous silica core. The formed HMRCs are photoresponsive and can be reversibly disassembled upon light irradiation, endowing them with an ability to release loaded cargo under photocontrol. While the assembled HMRCs retain cargo inside their cavity, disassembled particles with their iron oxide nanoparticle `caps' removed will release the loaded cargo through the mesoporous shell of the hollow silica colloids. A model system using a boronic acid derivative as the cargo in the HMRCs and Alizarin Red salt as a sensor for the released boronic acid is demonstrated. Electronic supplementary information (ESI) available. See DOI: 10.1039/C6NR01016D

  1. Microelectrofluidic lens for variable curvature

    Science.gov (United States)

    Chang, Jong-hyeon; Lee, Eunsung; Jung, Kyu-Dong; Lee, Seungwan; Choi, Minseog; Kim, Woonbae

    2012-10-01

    This paper presents a tunable liquid lens based on microelectrofluidic technology which integrates electrowetting and microfluidics. In the novel microelectrofluidic lens (MEFL), electrowetting in the hydrophobic surface channel induces the Laplace pressure difference between two fluidic interfaces on the lens aperture and the surface channel. Then, the pressure difference makes the lens curvature tunable. The previous electrowetting lens in which the contact angle changes at the side wall has a certain limitation of the curvature variation because of the contact angle saturation. Although the contact angle saturation also appears in the surface channel of the MEFL, the low surface channel increases the Laplace pressure and it makes the MEFL to have full variation of the optical power possible. The magnitude of the applied voltage determines the lens curvature in the analog mode MEFL as well as the electrowetting lens. Digital operation is also possible when the control electrodes of the MEFL are patterned to have an array. It is expected that the proposed MEFL is able to be widely used because of its full variation of the optical power without the use of oil and digital operation with fast response.

  2. The preparation and high-frequency electromagnetic properties of ferrimagnetic bisphthalonitrile–Fe{sub 3}O{sub 4} core–shell hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Junji; Du, Aiyu; Jin, Fei; Wang, Zicheng; Liu, Xiaobo, E-mail: liuxb@uestc.edu.cn

    2013-08-15

    A novel kind of ferrimagnetic core–shell hollow microsphere was prepared by a two-step solvothermal method with bisphthalonitrile and FeCl{sub 3}. Scanning electron microscope and transmission electron microscope images show that the diameter of hollow microsphere is about 320 nm and the hollow microspheres are made of small Fe{sub 3}O{sub 4} nanoparticles. Compared with traditional pure Fe{sub 3}O{sub 4} nanoparticles, the hollow microspheres exhibited very strong magnetism due to their special structures. The saturation magnetization and coercivity of the ferrimagnetic hollow microspheres were 103.9 emu g{sup −1} and 161.6 Oe, respectively. The electromagnetic properties of hybrids showed cooperative nonlinear magnetic and dielectric resonance in Ku-band. Moreover, the hybrid hollow microspheres also showed electromagnetic shielding characteristics in Ku-band. Three nesting reflection loss peaks can be seen around 13.0, 16.0 and 17.3 GHz. A minimum reflection loss of −38.5 dB was reached at 17.3 GHz with an absorber thickness of 4.2 mm. - Highlights: • A novel kind of ferrimagnetic core–shell hollow microspheres was prepared. • The core–shell microspheres showed strong magnetism. • The sample showed cooperative nonlinear magnetic resonance in Ku-band. • The microspheres showed absorption properties only in Ku-band.

  3. Microfabricated hollow microneedle array using ICP etcher

    Energy Technology Data Exchange (ETDEWEB)

    Ji Jing [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Tay, Francis E H [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Miao Jianmin [MicroMachines Center, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF{sub 6}/O{sub 2} isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  4. Microfabricated hollow microneedle array using ICP etcher

    Science.gov (United States)

    Ji, Jing; Tay, Francis E. H.; Miao, Jianmin

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF6/O2 isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  5. Bioreactor design considerations for hollow organs.

    Science.gov (United States)

    Fish, Jeff; Halberstadt, Craig; McCoy, Darell W; Robbins, Neil

    2013-01-01

    There are many important considerations in the design, construction, and use of a bioreactor for growing hollow organs such as vessels, gastrointestinal tissue, esophagus, and others. The growth of new organs requires a specialized container that provides sterility and an environment conducive to cell-seeding and attachment onto a three-dimensional bioabsorbable porous scaffold, incubation, maturation, and shipping for implantation. The materials' selection, dimensions, manufacturing, testing, and use of the bioreactor are all factors that should be considered in designing a bioreactor for the development of hollow organs.

  6. Scaffold Characteristics for Functional Hollow Organ Regeneration

    Directory of Open Access Journals (Sweden)

    Daniel Eberli

    2010-01-01

    Full Text Available Many medical conditions require surgical reconstruction of hollow organs. Tissue engineering of organs and tissues is a promising new technique without harvest site morbidity. An ideal biomaterial should be biocompatible, support tissue formation and provide adequate structural support. It should degrade gradually and provide an environment allowing for cell-cell interaction, adhesion, proliferation, migration, and differentiation. Although tissue formation is feasible, functionality has never been demonstrated. Mainly the lack of proper innervation and vascularisation are hindering contractility and normal function. In this chapter we critically review the current state of engineering hollow organs with a special focus on innervation and vascularisation.

  7. Synthesis and Characterization of Hollow Magnetic Alloy (GdNi2, Co5Gd Nanospheres Coated with Gd2O3

    Directory of Open Access Journals (Sweden)

    Wang Li

    2014-01-01

    Full Text Available Uniform magnetic hollow nanospheres (GdNi2, Co5Gd coated with Gd2O3 have been successfully prepared on a large scale via a urea-based homogeneous precipitation method using silica (SiO2 spheres as sacrificed templates, followed by subsequent heat treatment. Nitrogen sorption measurements and scanning electron microscope reveal that these hollow-structured magnetic nanospheres have the mesoporous shells that are composed of a large amount of uniform nanoparticles. After reduction treatment, these nanoparticles exhibit superparamagnetism that might have potential applications in medicine. Furthermore, the developed synthesis route may provide an important guidance for the preparation of other multifunctional hollow spherical materials.

  8. The Hollow-Face Illusion in Infancy: Do Infants See a Screen Based Rotating Hollow Mask as Hollow?

    Directory of Open Access Journals (Sweden)

    Aki Tsuruhara

    2011-06-01

    Full Text Available We investigated whether infants experience the hollow-face illusion using a screen-based presentation of a rotating hollow mask. In experiment 1 we examined preferential looking between rotating convex and concave faces. Adults looked more at the concave—illusory convex—face which appears to counter rotate. Infants of 7- to 8-month-old infants preferred the convex face, and 5- to 6-month-olds showed no preference. While older infants discriminate, their preference differed from that of adults possibly because they don't experience the illusion or counter rotation. In experiment 2 we tested preference in 7- to 8-month-olds for angled convex and concave static faces both before and after habituation to the stimuli shown in experiment 1. The infants showed a novelty preference for the static shape opposite to the habituation stimulus, together with a general preference for the static convex face. This shows that they discriminate between convex and concave faces and that habituation to either transfers across a change in view. Seven- to eight-month-olds have been shown to discriminate direction of rigid rotation on the basis of perspective changes. Our results suggest that this, perhaps together with a weaker bias to perceive faces as convex, allows these infants to see the screen-based hollow face as hollow even though adults perceive it as convex.

  9. Lens surface roughening for tears invariant contact lens performance

    Science.gov (United States)

    Zalevsky, Zeev; Azogui, Jonathan; Limon, Ofer; Rudnitsky, Arkady

    2014-03-01

    In many extended depth of focus diffractive or interferometry based ophthalmic contact lenses the time varied tears layers affect the ophthalmic functionality of the lens. In this paper we present a new approach involving nano pillars realized inside the grooves of a contact lens aiming to implement any type of extended depth of focus or diffractive optical element for ophthalmic applications in order to solve the micro fluidics layer uncertainty within the micro sag features.

  10. Contact Allergy To Hard Contact Lens

    Directory of Open Access Journals (Sweden)

    J S Pasricha

    1985-01-01

    Full Text Available Three patients developed recurrent irritation, redness and watery discharge from their eyes after using hard contact lens. Patch tests were positive with the material of the hard contact lens and negative with teepol, sodium lauryl sulphate and material of the soft contact lens. All the three patients became alright after they stopped,using hard contact lens.

  11. Self-assembly of hollow MoS{sub 2} microflakes by one-pot hydrothermal synthesis for efficient electrocatalytic hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Aishi; Cui, Renjie; He, Yanna; Wang, Qi [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); Zhang, Jian, E-mail: iamjzhang@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); Yang, Jianping [School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210023 (China); Li, Xing’ao, E-mail: lxahbmy@126.com [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210023 (China)

    2017-07-31

    Highlights: • A new hollow MoS{sub 2} microflakes are prepared by hydrothermal synthesis firstly. • SEM and TEM study show the structural nature of hollow microflakes in depth. • The unique hollow structures have large surface area owing to the cavity. • The hollow microflakes show better HER performance than their solid counterparts. - Abstract: Molybdenum disulfide (MoS{sub 2}) has emerged as a promising non-precious metal catalyst for hydrogen evolution reaction (HER) in recent years. Some strategies including nanotechnology as well as atom doping have been employed in the preparing of electrocatalysts for high-activity and stability. To the best of our knowledge, hollow MoS{sub 2} microflakes assembled from ultrathin nanosheets have not been prepared previously. In this work, a simple, facile and environmentally friendly hydrothermal synthesis was utilized for the fabrication of hollow MoS{sub 2} microflakes for the first time. The unique hollow structures have fascinating properties, such as the large surface and low density. The morphology and structure of MoS{sub 2} microflakes were confirmed by XRD, SEM, TEM and Raman. The composition of these materials was identified by the X-ray photoelectron spectroscopy. Notably, the as-prepared hollow MoS{sub 2} microflakes showed better electrocatalytic activity than other samples. The hollow flake-like structure can not only increase the active edge sites owing to the large specific surface area, but also enhance the electron transport to improve the electrocatalytic activity. Benefiting from these factors, the hollow MoS{sub 2} microflakes exhibited electrocatalytic activity and excellent stability with a low overpotential about 85 mV and a Tafel slope of 59 mV per decade.

  12. Hollow circular-truncated cone resonator and its hollow variable biconical laser beam

    Science.gov (United States)

    Liu, Jinglun; Chen, Mei; Wang, Qionghua; Sun, Nianchun

    2014-05-01

    To obtain a hollow variable biconical laser beam (HVBLB), a CO2 laser having a hollow circular-truncated cone resonator (HCTCR) is presented. This HCTCR comprises a rotationally symmetric total-reflecting concave mirror at the bottom, a rotationally symmetric part-reflecting convex mirror at the top, and a hollow circular-truncated cone discharge tube at the middle. The cross section of this generated biconical laser beam changes from annulus to circular to annulus and the size of this cross section from big to small to large as the propagation distance increases. So, a kind of laser beam with variable center intensity from zero to peak value to zero is obtained and is known as HVBLB. Due to the inclusion of part of the hollow laser beam (HLB) and solid laser beam, this HVBLB requires no additional beam-shaping element and has broad applications such as optical trapping and commercial manufacturing.

  13. A Prototype Antifungal Contact Lens

    OpenAIRE

    Ciolino, Joseph B; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.; Kohane, Daniel S.

    2011-01-01

    Econazole-eluting contact lenses with a novel design provided extended antifungal activity against the Candida albicans fungus. This drug-eluting contact lens could be used to treat and prevent fungal ocular infections.

  14. Cataract mutations and lens development.

    Science.gov (United States)

    Graw, J

    1999-03-01

    The lens plays an essential role for proper eye development. Mouse mutants affecting lens development are excellent models for corresponding human disorders. Moreover, using mutations in particular genes the process of eye and lens development can be dissected into distinct steps. Therefore, three mouse mutants will be described in detail and discussed affecting three essential stages: formation of the lens vesicle, initiation of secondary lens fiber cell formation, and terminal differentiation of the secondary fiber cells. The mutant aphakia (ak) has been characterized by bilaterally apakic eyes [Varnum and Stevens (1968) J. Hered. 59, 147-150], and the corresponding gene was mapped to chromosome 19 [Varnum and Stevens (1975) Mouse News Letters 53, 35]. Recent investigations in our laboratory refined the linkage 0.6 +/- 0.3 N cm proximal to the microsatellite marker D19Mit10. The linked gene Pax2, responsible for proper development of the posterior part of the eye and the optic nerve, was excluded as candidate gene by sequence analysis. Histological analysis of the homozygous ak mutants revealed a persisting lens stalk and subsequently the formation of lens rudiments. The lens defects led to irregular iris development and retinal folding. Congenital aphakia is known as a rare human anomaly. Besides a corneal dystrophy (CDTB), no corresponding disease is localized at the homologous region of human chromosome 10q23. The Cat3 mutations are characterized by vacuolated lenses caused by alterations in the beginning of secondary lens fiber cell differentiation at embryonic day 12.5. Secondary malformations develop at the cornea and the iris, but the retina remains unaffected. Two mutant alleles of the Cat3 locus have been mapped to mouse chromosome 10 very close to the microsatellite markers D10Mit41 and D10Mit95 (less than 0.3 cM). Since Cat3 is mapped to a position, which is homologous to human chromosome 12q21-24, the disorder cornea plana congenita can be considered

  15. Hollow fibre supported liquid membrane extraction of ...

    African Journals Online (AJOL)

    A simple sample pre-treatment method utilizing hollow fibre supported liquid membrane (HFSLM) was carried out on pharmaceuticals samples comprising of cough syrups (CS1 and CS2) and an anti-inflammatory product (AI). The active ingredients targeted in the extraction process were diphenylhydramine (DPH), ...

  16. Electromagnetic and microwave absorbing properties of hollow ...

    Indian Academy of Sciences (India)

    A mass of hollow carbon nanospheres (HCNSs) was fabricated by chemical vapour deposition of methane over Ni/Al2O3 catalyst at 600 °C. The products were ... Airworthiness Certification Technology Research and Management Centre, Civil Aviation University of China, Tianjin 300 300, China; School of Materials Science ...

  17. Smart Reinvention of the Contact Lens with Graphene.

    Science.gov (United States)

    Choi, Kyoungjun; Park, Hyung Gyu

    2017-06-27

    With potential benefits to the 71 million contact lens users worldwide, contact lenses are being reinvented in the form of smart wearable electronics. In this issue of ACS Nano, Lee et al. report on the fascinating functions of a graphene-based smart contact lens that is able to protect eyes from electromagnetic waves and dehydration. Graphene and two-dimensional materials can be exploited in many opportunities in the development of smart contact lenses. Here, we briefly review and describe prospects for the future of smart contact lenses that incorporate graphene in their platforms.

  18. Single lens laser beam shaper

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA

    2011-10-04

    A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

  19. Trisodium citrate-assisted synthesis of highly water-dispersible and superparamagnetic mesoporous Fe{sub 3}O{sub 4} hollow microspheres via solvothermal process

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xi; Wang, Fumin; Cai, Wangfeng; Zhang, Xubin, E-mail: tjzxb@tju.edu.cn

    2015-07-05

    Highlights: • Mesoporous Fe{sub 3}O{sub 4} hollow microspheres were prepared by a facile trisodium citrate-assisted solvothermal method. • The product exhibits high water-dispersibility and superparamagnetism at room temperature. • Ostwald ripening process was responsible for the formation of hollow structures. • The Fe{sub 3}O{sub 4} hollow microspheres are ideal candidates for various biomedical applications. - Abstract: Highly water-dispersible and superparamagnetic mesoporous Fe{sub 3}O{sub 4} hollow microspheres were prepared by a facile trisodium citrate-assisted solvothermal method. The composition, morphology and structure of the product were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis, Brunauer–Emmett–Teller (BET) and vibrating sample magnetometer (VSM). The results showed that the obtained Fe{sub 3}O{sub 4} hollow microspheres were composed of nanoparticles about 21 nm in diameter and exhibited superparamagnetic properties with relatively high saturation magnetization at room temperature. Trisodium citrate played a crucial role as an electrostatic stabilizer in the formation of Fe{sub 3}O{sub 4} hollow microspheres and Ostwald ripening process was responsible for the formation of hollow structures. The Fe{sub 3}O{sub 4} hollow microspheres were mesoporous and highly water-dispersible, indicating that the Fe{sub 3}O{sub 4} hollow microspheres are ideal candidates for various biomedical applications.

  20. Preparation of hollow core/shell microspheres of hematite and its adsorption ability for samarium.

    Science.gov (United States)

    Yu, Sheng-Hui; Yao, Qi-Zhi; Zhou, Gen-Tao; Fu, Sheng-Quan

    2014-07-09

    Hollow core/shell hematite microspheres with diameter of ca. 1-2 μm have been successfully achieved by calcining the precursor composite microspheres of pyrite and polyvinylpyrrolidone (PVP) in air. The synthesized products were characterized by a wide range of techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and Brunauer-Emmett-Teller (BET) gas sorptometry. Temperature- and time-dependent experiments unveil that the precursor pyrite-PVP composite microspheres finally transform into hollow core/shell hematite microspheres in air through a multistep process including the oxidation and sulfation of pyrite, combustion of PVP occluded in the precursor, desulfation, aggregation, and fusion of nanosized hematite as well as mass transportation from the interior to the exterior of the microspheres. The formation of the hollow core/shell microspheres dominantly depends on the calcination temperature under current experimental conditions, and the aggregation of hematite nanocrystals and the core shrinking during the oxidation of pyrite are responsible for the formation of the hollow structures. Moreover, the adsorption ability of the hematite for Sm(III) was also tested. The results exhibit that the hematite microspheres have good adsorption activity for trivalent samarium, and that its adsorption capacity strongly depends on the pH of the solution, and the maximum adsorption capacity for Sm(III) is 14.48 mg/g at neutral pH. As samarium is a typical member of the lanthanide series, our results suggest that the hollow hematite microspheres have potential application in removal of rare earth elements (REEs) entering the water environment.

  1. A course in lens design

    CERN Document Server

    Velzel, Chris

    2014-01-01

    A Course in Lens Design is an instruction in the design of image-forming optical systems. It teaches how a satisfactory design can be obtained in a straightforward way. Theory is limited to a minimum, and used to support the practical design work. The book introduces geometrical optics, optical instruments and aberrations. It gives a description of the process of lens design and of the strategies used in this process. Half of its content is devoted to the design of sixteen types of lenses, described in detail from beginning to end. This book is different from most other books on lens design because it stresses the importance of the initial phases of the design process: (paraxial) lay-out and (thin-lens) pre-design. The argument for this change of accent is that in these phases much information can be obtained about the properties of the lens to be designed. This information can be used in later phases of the design. This makes A Course in Lens Design a useful self-study book, and a suitable basis for an intro...

  2. Y2O3:Eu3+ core-in-multi-hollow microspheres: facile synthesis and luminescence properties.

    Science.gov (United States)

    Liu, Guixia; Liu, Shujun; Dong, Xiangting; Wang, Jinxian

    2011-11-01

    Y2O3:Eu3+ core-in-multi-hollow microspheres were synthesized via a facile hydrothermal method in the presence of glucose followed by a subsequent heat-treatment process. X-ray diffraction (XRD) pattern shows that the as-obtained hollow spheres are cubic phase of Y2O3. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images indicate that the samples are three layer hollow spheres with a diameter of 2-4 microm and the outermost wall thickness of 100 nm, the size of the inner core is about 300-400 nm, and the sub-outer wall thickness is about 100 nm. X-ray energy dispersive spectrum (EDS) shows that the samples are composed of Y, Eu and O. Photoluminescence spectra show that the hollow spheres have a strong characteristic red emission corresponding to the 5D0 - 7F2 transition of Eu3+ ions under ultraviolet excitation. This method can be used to synthesize other rare earth oxide hollow luminescent materials.

  3. Highly uniform hollow GdF3 spheres: controllable synthesis, tuned luminescence, and drug-release properties.

    Science.gov (United States)

    Lv, Ruichan; Gai, Shili; Dai, Yunlu; Niu, Na; He, Fei; Yang, Piaoping

    2013-11-13

    In this paper, uniform hollow mesoporous GdF3 micro/nanospheres were successfully prepared by a facile two-step synthesis route without using any surfactant, catalyst, and further calcination process. The precursor Gd(OH)CO3 spheres are prepared by a coprecipitation process. After that, uniform and size-tunable GdF3 hollow spheres were easily coprecipitated with NaBF4 at the sacrifice of the precursor with low temperature and short reaction time. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution TEM, N2 adsorption/desorption, and up-conversion (UC) photoluminescence spectra were used to characterize the as-obtained products. It is found that the initial pH value and NaBF4/Gd(3+) molar ratios play important roles in the structures, sizes, and phases of the hollow products. The growth mechanism of the hollow spheres has been systematically investigated based on the Kirkendall effect. Under 980 nm IR laser excitation, UC luminescence of the as-prepared Yb(3+)/Er(3+)-codoped GdF3 hollow spheres can be changed by a simple adjustment of the concentration of the Yb(3+) ion. Enhanced red emission is obtained by introducing Li(+) ions in GdF3:Yb(3+)/Er(3+). Furthermore, a doxorubicin release experiment and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide cytotoxicity assay reveal that the product has potential application in drug delivery and targeted cancer therapy.

  4. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...... is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible...

  5. Bacterial and fungal biofilm formation on contact lenses and their susceptibility to lens care solutions.

    Science.gov (United States)

    Kackar, Siddharth; Suman, Ethel; Kotian, M Shashidhar

    2017-01-01

    Microbial biofilm formation on contact lenses and lens storage cases may be a risk factor for contact lens-associated corneal infections. Various types of contact lens care solutions are used to reduce microbial growths on lenses. The present study aimed at comparing the growths of biofilms on the different contact lenses and lens cases. The study also aimed at determining the effect of lens care solutions and bacteriophage on these biofilms. One type of hard lens and two types of soft lenses were used for the study. The organisms used were Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 60193 and Escherichia coli ATCC 25922. Biofilm production was performed by modified O'Toole and Kolter method and effect of lens cleaning solutions and a crude coliphage on biofilms was also studied. Results were visualised using scanning electron microscopy and quantitated by colony counting method and spectrophotometric measurement of optical density (OD). Statistical analysis was done by SPSS 11.5, Kruskal-Wallis test and Chi-square test. Soft lens cleaning solutions had a significant inhibitory effect (P = 0.020) on biofilm formation on soft lenses and also lens cases (P contact lenses.

  6. Bacterial and fungal biofilm formation on contact lenses and their susceptibility to lens care solutions

    Directory of Open Access Journals (Sweden)

    Siddharth Kackar

    2017-01-01

    Full Text Available Background: Microbial biofilm formation on contact lenses and lens storage cases may be a risk factor for contact lens-associated corneal infections. Various types of contact lens care solutions are used to reduce microbial growths on lenses. Objectives: The present study aimed at comparing the growths of biofilms on the different contact lenses and lens cases. The study also aimed at determining the effect of lens care solutions and bacteriophage on these biofilms. Materials and Methods: One type of hard lens and two types of soft lenses were used for the study. The organisms used were Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 60193 and Escherichia coli ATCC 25922. Biofilm production was performed by modified O'Toole and Kolter method and effect of lens cleaning solutions and a crude coliphage on biofilms was also studied. Results were visualised using scanning electron microscopy and quantitated by colony counting method and spectrophotometric measurement of optical density (OD. Statistical analysis was done by SPSS 11.5, Kruskal–Wallis test and Chi-square test. Results: Soft lens cleaning solutions had a significant inhibitory effect (P = 0.020 on biofilm formation on soft lenses and also lens cases (P < 0.001. Soft lens cleaning solution 2 was more efficient than solution 1. However, no such inhibitory effect was observed with regard to hard lens cleaning solution, but for a significant reduction in the OD values (P < 0.001. There was no significant inhibitory effect by bacteriophages. Conclusion: This study showed the importance of selecting the appropriate lens cleaning solution to prevent biofilm production on contact lenses.

  7. A framework of cloud supported collaborative design in glass lens moulds based on aspheric measurement

    Science.gov (United States)

    Zhu, Yongjian; Wang, Yu; Na, Jingxin; Zhi, Yanan; Fan, Yufeng

    2013-09-01

    Aspheric mould design includes the top-down design and reversal design. In this paper, a new framework of reversal design is proposed combining with cloud supported collaborative design (CSCD) based on aspheric measurement. The framework is a kind of collaborative platform, which is composed of eight modules, including the computerized aspheric precision measurement module (CAPM), computer-aided optical design of aspheric lens system (CAOD), computer-aided design of lens mould (CADLM), FEM(finite element method) simulation of lens molding module (FEMLM), computer-aided manufacture of lens and moulds (CAMLM), measurement data analysis module (MDAM), optical product lifecycle management module (OPLM) and cloud computing network module (CCNM). In this framework, the remote clients send an improved requirement or fabrication demand about optical lens system through CCNM, which transfers this signal to OPLM. In OPLM, one main server is in charge of the task distribution and collaborative work of other six modules. The first measurement data of aspheric lens are produced by clients or our proposed platform CAPM, then are sent to CAOD for optimization and the electronic drawings of lens moulds are generated in CADLM module. According the design drawings, the FEMLM could give the lens-molding simulation parameters through FEM software. The simulation data are used for the second design of moulds in CADLM module. In this case, the moulds could be fabricated in CAMLM by ultra-precision machine, and the aspheric lens could be also produced by lens-molding machine in CAMLM. At last, the final shape of aspheric lens could be measured in CAPM and the data analysis could be conducted in MDAM module. Through the proposed framework, all the work described above could be performed coordinately. And the optimum design data of lens mould could be realized and saved, then shared by all the work team.

  8. Individual hollow and mesoporous aero-graphitic microtube based devices for gas sensing applications

    Science.gov (United States)

    Lupan, Oleg; Postica, Vasile; Marx, Janik; Mecklenburg, Matthias; Mishra, Yogendra K.; Schulte, Karl; Fiedler, Bodo; Adelung, Rainer

    2017-06-01

    In this work, individual hollow and mesoporous graphitic microtubes were integrated into electronic devices using a FIB/SEM system and were investigated as gas and vapor sensors by applying different bias voltages (in the range of 10 mV-1 V). By increasing the bias voltage, a slight current enhancement is observed, which is mainly attributed to the self-heating effect. A different behavior of ammonia NH3 vapor sensing by increasing the applied bias voltage for hollow and mesoporous microtubes with diameters down to 300 nm is reported. In the case of the hollow microtube, an increase in the response was observed, while a reverse effect has been noticed for the mesoporous microtube. It might be explained on the basis of the higher specific surface area (SSA) of the mesoporous microtube compared to the hollow one. Thus, at room temperature when the surface chemical reaction rate (k) prevails on the gas diffusion rate (DK) the structures with a larger SSA possess a higher response. By increasing the bias voltage, i.e., the overall temperature of the structure, DK becomes a limiting step in the gas response. Therefore, at higher bias voltages the larger pores will facilitate an enhanced gas diffusion, i.e., a higher gas response. The present study demonstrates the importance of the material porosity towards gas sensing applications.

  9. Sensitive Nonenzymatic Electrochemical Glucose Detection Based on Hollow Porous NiO

    Science.gov (United States)

    He, Gege; Tian, Liangliang; Cai, Yanhua; Wu, Shenping; Su, Yongyao; Yan, Hengqing; Pu, Wanrong; Zhang, Jinkun; Li, Lu

    2018-01-01

    Transition metal oxides (TMOs) have attracted extensive research attentions as promising electrocatalytic materials. Despite low cost and high stability, the electrocatalytic activity of TMOs still cannot satisfy the requirements of applications. Inspired by kinetics, the design of hollow porous structure is considered as a promising strategy to achieve superior electrocatalytic performance. In this work, cubic NiO hollow porous architecture (NiO HPA) was constructed through coordinating etching and precipitating (CEP) principle followed by post calcination. Being employed to detect glucose, NiO HPA electrode exhibits outstanding electrocatalytic activity in terms of high sensitivity (1323 μA mM-1 cm-2) and low detection limit (0.32 μM). The excellent electrocatalytic activity can be ascribed to large specific surface area (SSA), ordered diffusion channels, and accelerated electron transfer rate derived from the unique hollow porous features. The results demonstrate that the NiO HPA could have practical applications in the design of nonenzymatic glucose sensors. The construction of hollow porous architecture provides an effective nanoengineering strategy for high-performance electrocatalysts.

  10. Hollow nickel-aluminium-manganese layered triple hydroxide nanospheres with tunable architecture for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Chandrasekaran, Nivedhini Iswarya; Muthukumar, Harshiny; Sekar, Aiswarya Devi; Manickam, Matheswaran, E-mail: math.chem95@gmail.com

    2017-07-01

    Hollow triple layered Ni-Al-Mn hydroxide nanocomposite is a promising electrode material with high capacitance value. Moreover, the material provides a high energy density with good cycling stability. Here we demonstrate the facile method for preparation of hollow layered triple hydroxide material in a combination of Nickel, Aluminium and Manganese with high surface area and mesoporous nature. Owing to its high electrode area and fast electron-ion transfer nature, the hollow Ni-Al-Mn hydroxide exhibits the high capacitance of 1756 F/g at 4 A/g and retains its capacitance value upto 89.5% of initial values after 4000 cycles. Additionally, it provides a higher energy density of 239.0795 Wh/kg at a power density of 1980 W/kg. HLTH of Ni-Al-Mn nanocomposite provides a better capacitance effect. Finally, this material provides a general approach for designing supercapacitor with tunable nanostructure and enhanced supercapacitor behaviour has a large application in energy storage and conversion devices. - Highlights: • An approach to acquire a hollow Ni-Al-Mn layered triple hydroxide is presented. • HLTH shows a large surface area suitable for electrochemical performance. • Exhibits high energy density of 239.07 Wh/kg at a power density of 1980 W/kg. • Recorded specific capacitance of 1756 F/g at current density 4 A/g. • HLTH retains 89.5% of initial capacitance values after 4000 cycles.

  11. Electrospun manganese-cobalt oxide hollow nanofibres synthesized via combustion reactions and their lithium storage performance

    Science.gov (United States)

    Hwang, Soo Min; Kim, So Yeun; Kim, Jae-Geun; Kim, Ki Jae; Lee, Jong-Won; Park, Min-Sik; Kim, Young-Jun; Shahabuddin, Mohammed; Yamauchi, Yusuke; Kim, Jung Ho

    2015-04-01

    Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries.Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries. Electronic supplementary information (ESI) available: Experimental section; additional thermal analyses; XRD patterns; SEM and TEM results; N2 adsorption isotherms; differential capacity plots of galvanostatic voltage profiles and coulombic efficiency during cycling. See DOI: 10.1039/c5nr01145k

  12. Low-temperature solvothermal synthesis of EuS hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Yong; Wang, Hong; Li, Peng; Fu, Yao, E-mail: fuyaozn@126.com; Xing, Mingming; Jiang, Tao; Luo, Xixian, E-mail: luoxixiandl@126.com

    2014-09-15

    Graphical abstract: Synthesis of EuS hollow microspheres at low-temperature via solvothermal method for the first time. - Highlights: • We adopt an improved method to synthesise the (Phen)Eu(Et{sub 2}CNS{sub 2}){sub 3} in deionized water. • We have successfully synthesised the EuS hollow microsphere at 230 °C in acetonitrile. • The price of acetonitrile is more inexpensive, so the price of preparation was reduced. - Abstract: EuS crystals are synthesized by low-temperature solvothermal decomposition of the single source precursor complex (Phen)Eu(Et{sub 2}CNS{sub 2}){sub 3} in acetonitrile. X-ray powder diffraction, scanning electron microscopy, granulocyte diameter statistical analysis, surface energy-dispersive X-ray spectroscopy analysis, and UV–vis absorption spectroscopy are used to characterize the structure and properties of the obtained EuS crystals. The results show that the formed EuS crystals are uniform hollow microspheres with a typical cubic phase structure of rock salt and the average particle size of 2.01 μm. The mechanisms for the thermal decomposition of the precursor complex and the formation of the EuS hollow microspheres are postulated based on the experimental observations and previous reports.

  13. Hollow fiber membranes with different external corrugated surfaces for desalination by membrane distillation

    Science.gov (United States)

    García-Fernández, Loreto; García-Payo, Carmen; Khayet, Mohamed

    2017-09-01

    Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were prepared using the phase inversion spinning technique under a wet gap mode. Different corrugated outer surfaces were obtained by means of a micro-engineered spinneret, spraying the external coagulant on the nascent fiber along gap, and different spinning parameters, namely, the gap distance and the external coagulant flow rate. A quantitative evaluation of the corrugation size and shape was carried out by electron scanning microscopy and atomic force microscopy. The effect of the corrugation size and shape on the direct contact membrane distillation (DCMD) performance has been studied. The corrugated outer surface acted as micro-turbulence promoters mitigating the temperature polarization effect and enhanced the external effective surface area for condensation. Both factors improved the DCMD permeability of the hollow fiber membranes. However, corrugations with V-shaped valleys depths greater than about 30 μm did not always improve the DCMD permeate flux. It was found that the membrane prepared with the spray wetting mode exhibited the best desalination performance. The salt rejection factor of all prepared hollow fiber membranes was greater than 99.9% and the highest DCMD permeate flux of this study was greater than those reported so far for the PVDF-HFP hollow fiber membranes.

  14. Actual Stationary State for Plasma Lens

    CERN Document Server

    Zadorozhny, Vladimir F; Parsa, Zohreh

    2005-01-01

    The electrostatic plasma lens (PL) provides an attractive and unique tool for manipulating high-current heavy ion beams. The fundamental concept of the PL is based on the use of magnetically insulated electrons and equipotentialization of magnetic field lines. Rigorous application of PL is, however, limited. The reason is the estimation behaviour of electrons for complicated magnetic fields runs into severe difficults.We show that there are specific conditions that admit steady-state of a longitudinal motion, and consider a question of it stability. These results are needed to develop an optimized PL with minimal spherical aberation, in party by optimization of the magnetic field conficuration in the low-magnetic-field range.

  15. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    Science.gov (United States)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  16. InOOH hollow spheres synthesized by a simple hydrothermal reaction.

    Science.gov (United States)

    Zhu, Hongliang; Yao, Kuihong; Zhang, Hui; Yang, Deren

    2005-11-10

    Novel micrometer-sized indium oxyhydroxide (InOOH) hollow spheres were successfully synthesized via a citric acid (CA) assisted hydrothermal process. The morphology, crystal structure, and optical properties of the product were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and UV-vis diffuse reflectance spectroscopy (DRS). The optical band gap, E(g), was estimated to be 3.5 eV from the DRS spectrum, which is almost equal to that of indium oxide. Furthermore, on the basis of a series of SEM observations, phenomenological elucidation of a mechanism for the growth of the InOOH hollow spheres has been presented; key factors for the formation of the structures have been proposed.

  17. Microscopic and spectroscopic investigation of an explanted opacified intraocular lens

    Energy Technology Data Exchange (ETDEWEB)

    Simon, V., E-mail: viosimon@phys.ubbcluj.ro [Babeş-Bolyai University, Faculty of Physics and Interdisciplinary Research Institute on Bio-Nano-Sciences, 400084 Cluj-Napoca (Romania); Radu, T.; Vulpoi, A. [Babeş-Bolyai University, Faculty of Physics and Interdisciplinary Research Institute on Bio-Nano-Sciences, 400084 Cluj-Napoca (Romania); Rosca, C. [Optilens Clinic of Ophthalmology, 400604 Cluj-Napoca (Romania); Eniu, D. [Iuliu Haţieganu University of Medicine and Pharmacy, Department of Molecular Sciences, 400349 Cluj-Napoca (Romania)

    2015-01-15

    Highlights: • Changes on intraocular lens (IOL) surface after implantation. • Partial opacification of IOL central area. • Elemental composition on IOL surface prior to and after implantation. • First XPS depth profiling examination of the opacifying deposits. • Cell-mediated hydroxyapatite structuring. - Abstract: The investigated polymethylmethacrylate intraocular lens explanted an year after implantation presented a fine granularity consisting of ring-like grains of about 15 μm in diameter. In order to evidence the changes occurred on intraocular lens relative to morphology, elemental composition and atomic environments, microscopic and spectroscopic analyses were carried out using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), energy-dispersive X-ray (EDS), and X-ray photoelectron (XPS) spectroscopies. The results revealed that the grains contain hydroxyapatite mineral phase. A protein layer covers the lens both in opacified and transparent zones. The amide II band is like in basal epithelial cells. The shape and size of the grains, and the XPS depth profiling results indicate the possibility of a cell-mediated process involving lens epithelial cells which fagocitated apoptotic epithelial cells, and in which the debris derived from cell necrosis were calcified. To the best of our knowledge, this is the first investigation on explanted intraocular lenses using XPS depth profiling in order to examine the inside of the opacifying deposits.

  18. A facile synthesis of luminescent YVO4:Eu3+ hollow microspheres in virtue of template function of the SDS-PEG soft clusters

    Science.gov (United States)

    Wang, Juan; Yan, Yinglin; Hojamberdiev, Mirabbos; Ruan, Xiaoguang; Cai, Anjiang; Xu, Yunhua

    2012-08-01

    Hollow europium-doped yttrium orthovanadate (YVO4:Eu3+) microspheres were fabricated via a sodium dodecyl sulfate (SDS)-polyethylene glycol (PEG)-assisted hydrothermal technique. The as-synthesized hollow YVO4:Eu3+ microspheres were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). The obtained results showed that the morphology and size of the hollow microspheres have a strong dependence on the hydrothermal reaction time of the YVO4:Eu3+ powders. It is believed that the SDS-PEG clusters perform a function of dual soft-template that results in a unique template-induced secondary assembly in the one-pot synthesis of hollow YVO4:Eu3+ microspheres. The photoluminescence measurement revealed that the YVO4:Eu3+ powders with a spherical hollow shape have better red luminescence compared to the YVO4:Eu3+ solid microspheres. As a result, the controlled synthesis of hollow YVO4:Eu3+ microspheres not only has a great theoretical significance in studying the three-dimensional control and selective synthesis of inorganic materials but also benefits the potential applications based on hollow YVO4:Eu3+ microspheres owing to reducing the usage of expensive rare-earth elements.

  19. Hierarchical hollow spheres of Fe2O3 @polyaniline for lithium ion battery anodes.

    Science.gov (United States)

    Jeong, Jae-Min; Choi, Bong Gill; Lee, Soon Chang; Lee, Kyoung G; Chang, Sung-Jin; Han, Young-Kyu; Lee, Young Boo; Lee, Hyun Uk; Kwon, Soonjo; Lee, Gaehang; Lee, Chang-Soo; Huh, Yun Suk

    2013-11-20

    Hierarchical hollow spheres of Fe2 O3 @polyaniline are fabricated by template-free synthesis of iron oxides followed by a post in- and exterior construction. A combination of large surface area with porous structure, fast ion/electron transport, and mechanical integrity renders this material attractive as a lithium-ion anode, showing superior rate capability and cycling performance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. 3D Hollow Sn@Carbon-Graphene Hybrid Material as Promising Anode for Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Xiaoyu Zheng

    2014-01-01

    Full Text Available A 3D hollow Sn@C-graphene hybrid material (HSCG with high capacity and excellent cyclic and rate performance is fabricated by a one-pot assembly method. Due to the fast electron and ion transfer as well as the efficient carbon buffer structure, the hybrid material is promising in high-performance lithium-ion battery.

  1. Time lens assisted photonic sampling extraction

    Science.gov (United States)

    Petrillo, Keith Gordon

    Telecommunication bandwidth demands have dramatically increased in recent years due to Internet based services like cloud computing and storage, large file sharing, and video streaming. Additionally, sensing systems such as wideband radar, magnetic imaging resonance systems, and complex modulation formats to handle large data transfer in telecommunications require high speed, high resolution analog-to-digital converters (ADCs) to interpret the data. Accurately processing and acquiring the information at next generation data rates from these systems has become challenging for electronic systems. The largest contributors to the electronic bottleneck are bandwidth and timing jitter which limit speed and reduce accuracy. Optical systems have shown to have at least three orders of magnitude increase in bandwidth capabilities and state of the art mode locked lasers have reduced timing jitters into thousands of attoseconds. Such features have encouraged processing signals without the use of electronics or using photonics to assist electronics. All optical signal processing has allowed the processing of telecommunication line rates up to 1.28 Tb/s and high resolution analog-to-digital converters in the 10s of gigahertz. The major drawback to these optical systems is the high cost of the components. The application of all optical processing techniques such as a time lens and chirped processing can greatly reduce bandwidth and cost requirements of optical serial to parallel converters and push photonically assisted ADCs into the 100s of gigahertz. In this dissertation, the building blocks to a high speed photonically assisted ADC are demonstrated, each providing benefits to its own respective application. A serial to parallel converter using a continuously operating time lens as an optical Fourier processor is demonstrated to fully convert a 160-Gb/s optical time division multiplexed signal to 16 10-Gb/s channels with error free operation. Using chirped processing, an

  2. [Contact lens care and maintenance].

    Science.gov (United States)

    Bloise, L

    2017-04-01

    All contact lenses with replacement schedules longer than daily must be maintained. At each step of their use, the lenses may be contaminated. Contact lens solutions perform the essential functions of cleaning, decontaminating and preserving the lenses to prevent infectious problems and improve wearing comfort. Contact lens contamination essentially comes from hands, cleaning solutions, cases, water and the environment. The pathogenic microorganisms are mainly Gram-negative bacteria, fungi and amoebae. Contact lens deposits may or may not have an organic origin. Their presence increases the risk of infection because they serve as a nutrient matrix for microbes, and they are responsible for wearing discomfort. Contact lens solutions differ in their composition, their mechanism of action and the concentration of the various agents. To prescribe the best lens care system to each wearer and for each material, it is necessary to be very familiar with them. Maintenance is the main cause of discomfort with contact lenses, either through improper use, solution-material incompatibility, or a reaction of the wearer to the components. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  4. Mesoporous hollow spheres from soap bubbling.

    Science.gov (United States)

    Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

    2012-02-01

    The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. Space Charge Mitigation by Hollow Bunches

    CERN Multimedia

    Oeftiger, AO

    2014-01-01

    To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \\epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.

  6. Automated Fresnel lens tester system

    Energy Technology Data Exchange (ETDEWEB)

    Phipps, G.S.

    1981-07-01

    An automated data collection system controlled by a desktop computer has been developed for testing Fresnel concentrators (lenses) intended for solar energy applications. The system maps the two-dimensional irradiance pattern (image) formed in a plane parallel to the lens, whereas the lens and detector assembly track the sun. A point detector silicon diode (0.5-mm-dia active area) measures the irradiance at each point of an operator-defined rectilinear grid of data positions. Comparison with a second detector measuring solar insolation levels results in solar concentration ratios over the image plane. Summation of image plane energies allows calculation of lens efficiencies for various solar cell sizes. Various graphical plots of concentration ratio data help to visualize energy distribution patterns.

  7. [Contact lens-related keratitis].

    Science.gov (United States)

    Steiber, Zita; Berta, András; Módis, László

    2013-11-10

    Nowadays, keratitis, corneal infection due to wearing contact lens means an increasingly serious problem. Neglected cases may lead to corneal damage that can cause blindness in cases of otherwise healthy eyes. Early diagnosis based on the clinical picture and the typical patient history is an important way of prevention. Prophylaxis is substantial to avoid bacterial and viral infection that is highly essential in this group of diseases. Teaching contact lens wearers the proper contact lens care, storage, sterility, and hygiene regulations is of great importance. In case of corneal inflammation early accurate diagnosis supported by microbiological culture from contact lenses, storage boxes or cornea is very useful. Thereafter, targeted drug therapy or in therapy-resistant cases surgical treatment may even be necessary in order to sustain suitable visual acuity.

  8. Compliance among soft contact lens wearers.

    Science.gov (United States)

    Kuzman, Tomislav; Kutija, Marija Barisić; Masnec, Sanja; Jandroković, Sonja; Mrazovac, Danijela; Jurisić, Darija; Skegro, Ivan; Kalauz, Miro; Kordić, Rajko

    2014-12-01

    Contact lens compliance is proven to be crucial for preventing lens wear-related complications because of the interdependence of the steps in lens care regime and their influence on lens system microbial contamination. Awareness of the patients' lens handling compliance as well as correct recognition of non-compliant behaviours is the basis for creating more targeted strategies for patient education. The aim of this study was to investigate compliance among soft contact lens (SCL) wearers in different aspects of lens care handling and wearing habits. In our research 50 asymptomatic lens wearers filled out a questionnaire containing demographic data, lens type, hygiene and wearing habits, lenses and lens care system replacement schedule and self-evaluation of contact lens handling hygiene. We established criteria of compliance according to available manufacturer's recommendations, prior literature and our clinical experience. Only 2 (4%) of patients were fully compliant SCL wearers. The most common non-compliant behaviours were insufficient lens solution soaking time (62%), followed by failure to daily exchange lens case solution and showering while wearing lenses. 44% of patients reported storing lenses in saline solution. Mean lens storage case replacement was 3.6 months, with up to 78% patients replacing lens case at least once in 3 months. Average grade in self evaluating level of compliance was very good (4 +/- 0.78) (from 1-poor level of hygiene to 5-great level of hygiene). Lens wearers who reported excessive daily lens wear and more than 10 years of lens wearing experience were also found to be less compliant with other lens system care procedures. (t = -2.99, df=47, p lens system maintenance steps. Most common non-compliant behaviours were the ones that are crucial for maintaining lens sterility and preventing infection. Despite the low objective compliance rate, self grading was relatively high. Therefore, these results indicate the need for patient

  9. Template-Free Synthesis of Hollow-Structured Co 3 O 4 Nanoparticles as High-Performance Anodes for Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Deli; Yu, Yingchao; He, Huan; Wang, Jie; Zhou, Weidong; Abruña, Hector D.

    2015-02-24

    We have developed a template-free procedure to synthesize Co3O4 hollow-structured nanoparticles on a Vulcan XC-72 carbon support. The material was synthesized via an impregnation–reduction method followed by air oxidation. In contrast to spherical particles, the hollow-structured Co3O4 nanoparticles exhibited excellent lithium storage capacity, rate capability, and cycling stability when used as the anode material in lithium-ion batteries. Electrochemical testing showed that the hollow-structured Co3O4 particles delivered a stable reversible capacity of about 880 mAh/g (near the theoretical capacity of 890 mAh/g) at a current density of 50 mA/g after 50 cycles. The superior electrochemical performance is attributed to its unique hollow structure, which combines nano- and microscale properties that facilitate electron transfer and enhance structural robustness.

  10. Effects of copper content on the shell characteristics of hollow steel spheres manufactured using an advanced powder metallurgy technique

    Science.gov (United States)

    Sazegaran, Hamid; Kiani-Rashid, Ali-Reza; Khaki, Jalil Vahdati

    2016-04-01

    Metallic hollow spheres are used as base materials in the manufacture of hollow sphere structures and metallic foams. In this study, steel hollow spheres were successfully manufactured using an advanced powder metallurgy technique. The spheres' shells were characterized by optical microscopy in conjunction with microstructural image analysis software, scanning electron microscopy (SEM), energy- dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The microscopic evaluations revealed that the shells consist of sintered iron powder, sintered copper powder, sodium silicate, and porosity regions. In addition, the effects of copper content on various parameters such as shell defects, microcracks, thickness, and porosities were investigated. The results indicated that increasing the copper content results in decreases in the surface fraction of shell porosities and the number of microcracks and an increase in shell thickness.

  11. Contact lens care in keratoconus.

    Science.gov (United States)

    Zhou, Alana J; Kitamura, Keiko; Weissman, Barry A

    2003-12-01

    To quantify the complexity involved in fitting contact lenses on the eyes of patients with keratoconus. The contact lens care of one randomly selected eye each of 38 keratoconus patients was retrospectively analyzed and compared to that of 38 gender and age matched controls. We evaluated the number of diagnostic contact lenses used to establish the initial contact lens order, number of ordered rigid gas permeable (RGP) contact lenses needed to complete the fit, number of office visits during the initial 4 months of care, best spectacle and RGP contact lenses corrected Log MAR visual acuities, complications encountered, and whether or not the patient was successful in contact lens wear. Keratoconic eyes statistically used more diagnostic lenses, more ordered lenses, and more office visits than did normal eyes. Visual acuities improved from an average of 20/40 with spectacles to an average of 20/20 by use of RGP contact lenses in keratoconic eyes. Visions were corrected to 20/20 with both spectacles and contact lenses in control eyes. Sixty nine percent (69%) of keratoconic eyes and 95% of controls were successful in contact lens wear. Contact lens care of keratoconic eyes is more challenging than care of normal eyes because of the need for more diagnostic and ordered contact lenses and the use of more professional time. Keratoconic eyes may suffer more complications than normals during contact lens care, but this does not affect the success rates, and such patients benefit from enhanced visual acuity with RGP contact lenses compared to that achieved with spectacles.

  12. One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Bei Cheng

    2012-01-01

    Full Text Available Monoclinic-phase BiVO4 hollow microspheres with diameters of about 2–4 μm have been successfully fabricated in high yield by a one-pot template-free hydrothermal route. The reaction duration and urea concentration are shown to play important roles in the formation of the BiVO4 hollow microspheres. X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption isotherms, fourier transform infrared spectrometry, and UV-visible diffuse reflectance spectroscopy are used to characterize the products. The results show that all the as-prepared BiVO4 samples have monoclinic phase structure and exhibit good crystallinity. A formation mechanism for the BiVO4 hollow spherical structure via a localized Ostwald ripening is proposed based on the experimental observations. In addition, studies of the photocatalytic properties by exposure to visible light irradiation demonstrate that the as-obtained BiVO4 hollow spheres show potential photocatalytic application. Hydroxyl radicals (•OH are not detected on the surface of visible-light-illuminated BiVO4 by the photoluminescence technique, suggesting that •OH is not the dominant photooxidant and photogenerated hole could directly take part in photocatalytic reaction. The prepared BiVO4 hollow spheres are also of great interest in pigment, catalysis, separation technology, biomedical engineering, and nanotechnology.

  13. Three-dimensional interconnected cobalt oxide-carbon hollow spheres arrays as cathode materials for hybrid batteries

    Directory of Open Access Journals (Sweden)

    Jiye Zhan

    2016-06-01

    Full Text Available Hierarchical porous metal oxides arrays is critical for development of advanced energy storage devices. Herein, we report a facile template-assisted electro-deposition plus glucose decomposition method for synthesis of multilayer CoO/C hollow spheres arrays. The CoO/C arrays consist of multilayer interconnected hollow composite spheres with diameters of ∼350 nm as well as thin walls of ∼20 nm. Hierarchical hollow spheres architecture with 3D porous networks are achieved. As cathode of high-rate hybrid batteries, the multilayer CoO/C hollow sphere arrays exhibit impressive enhanced performances with a high capacity (73.5 mAh g−1 at 2 A g−1, and stable high-rate cycling life (70 mAh g−1 after 12,500 cycles at 2 A g−1. The improved electrochemical performance is owing to the composite hollow-sphere architecture with high contact area between the active materials and electrolyte as well as fast ion/electron transportation path.

  14. Topological robotics in lens spaces

    Science.gov (United States)

    González, Jesús

    2005-11-01

    Motivated by the work of Farber, Tabachnikov and Yuzvinsky on the motion planning problem for projective spaces, we give an estimate for the topological complexity (TC) of lens spaces in terms of certain generalized “skew” maps between spheres. This last concept turns out to be closely related to that for a generalized axial map developed by Astey, Davis and the author to characterize the smallest Euclidean dimension where (2-torsion) lens spaces can be immersed. As a result, this suggests an alternative simpler “TC-approach” to the classical immersion problem for real projective spaces, whose initial stages we settle by means of techniques in obstruction theory.

  15. Silica hollow spheres with nano-macroholes like diatomaceous earth.

    Science.gov (United States)

    Fujiwara, Masahiro; Shiokawa, Kumi; Sakakura, Ikuko; Nakahara, Yoshiko

    2006-12-01

    Artificial synthesis of hollow cell walls of diatoms is an ultimate target of nanomaterial science. The addition of some water-soluble polymers such as sodium polymethacrylate to a solution of water/oil/water emulsion system, which is an essential step of the simple synthetic procedure of silica hollow spheres (microcapsules), led to the formation of silica hollow spheres with nano-macroholes (>100 nm) in their shell walls, the morphologies of which are analogous to those of diatom earth.

  16. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-13

    Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

  17. Pinhole Viewing Strengthens the Hollow-Face Illusion

    OpenAIRE

    Koessler, Trent; Hill, Harold

    2015-01-01

    A hollow (concave) mask appears convex when viewed from beyond a certain distance even when viewed stereoscopically—this is the hollow-face illusion. At close viewing distances, the same mask is seen as hollow even when disparity information is eliminated by monocular viewing. A potential source of nonpictorial, monocular information that favors a veridical percept at close distances is accommodation in conjunction with focus blur. In this article, we used pinhole viewing to minimize this pot...

  18. Submicrometer Hollow Bioglass Cones Deposited by Radio Frequency Magnetron Sputtering: Formation Mechanism, Properties, and Prospective Biomedical Applications.

    Science.gov (United States)

    Popa, A C; Stan, G E; Besleaga, C; Ion, L; Maraloiu, V A; Tulyaganov, D U; Ferreira, J M F

    2016-02-01

    This work reports on the unprecedented magnetron sputtering deposition of submicrometric hollow cones of bioactive glass at low temperature in the absence of any template or catalyst. The influence of sputtering conditions on the formation and development of bioglass cones was studied. It was shown that larger populations of well-developed cones could be achieved by increasing the argon sputtering pressure. A mechanism describing the growth of bioglass hollow cones is presented, offering the links for process control and reproducibility of the cone features. The composition, structure, and morphology of the as-synthesized hollow cones were investigated by energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), grazing incidence geometry X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)-selected area electron diffraction (SAED). The in vitro biological performance, assessed by degradation tests (ISO 10993-14) and cytocompatibility assays (ISO 10993-5) in endothelial cell cultures, was excellent. This allied with resorbability and the unique morphological features make the submicrometer hollow cones interesting candidate material devices for focal transitory permeabilization of the blood-brain barrier in the treatment of carcinoma and neurodegenerative disorders.

  19. 21 CFR 886.3600 - Intraocular lens.

    Science.gov (United States)

    2010-04-01

    ... DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3600 Intraocular lens. (a) Identification. An... the natural lens of an eye. (b) Classification. Class III. (c) Date PMA or notice of completion of a...

  20. Highly uniform α-NaYF4:Yb/Er hollow microspheres and their application as drug carrier.

    Science.gov (United States)

    Han, Yunhua; Gai, Shili; Ma, Ping'an; Wang, Liuzhen; Zhang, Milin; Huang, Shaohua; Yang, Piaoping

    2013-08-19

    Highly uniform α-NaYF4:Yb/Er hollow microspheres have been successfully prepared via a simple two-step route. First, the core-shell structured MF@Y(OH)CO3:Yb/Er precursor was fabricated by a urea-based homogeneous precipitation method using colloidal melamine formaldehyde (MF) microspheres as template. Then the Y(OH)CO3:Yb/Er precursor was transformed into hollow NaYF4:Yb/Er (α and β mixed phase) by a subsequent solvothermal method, and MF microspheres were dissolved in the solvent simultaneously. The mixed phase of NaYF4:Yb/Er was transferred into pure α-NaYF4:Yb/Er by calcination. The as-prepared hollow microspheres were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrum (EDS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and upconversion (UC) luminescence spectroscopy. It is found that the template can be removed without additional calcination or etching process. α-NaYF4:Yb/Er hollow microspheres exhibit bright upconversion (UC) luminescence under 980 nm laser diode (LD) excitation. Furthermore, the hollow microspheres show sustained and pH-dependent doxorubicin hydrochloride (DOX) release properties; in particular, the emission intensity increases with the release amount of drug, making the release process able to be tracked or monitored by the change of the emission intensity, which demonstrates the high potential of this kind of hollow fluorescent material in drug delivery fields.

  1. Robust SiO2-modified CoFe2O4 hollow nanofibers with flexible room temperature magnetic performance.

    Science.gov (United States)

    Jing, Panpan; Pan, Lining; Du, Jinlu; Wang, Jianbo; Liu, Qingfang

    2015-05-21

    A range of robust SiO2-modified CoFe2O4 hollow nanofibers with high uniformity and productivity were successfully prepared via polyvinylpyrrolidone-sol assisted electrospinning followed by annealing at a high temperature of 1000 °C, and they were characterized using scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction and X-ray photoelectron spectroscopy in detail. It was demonstrated that amorphous SiO2 has a significant influence on not only the surface morphology, microstructure and crystalline size but also the room temperature magnetic performance of the inverse spinel CoFe2O4 nanofibers. The pure CoFe2O4 sample shows a particle chain rod-shape appearance but the SiO2-modified CoFe2O4 sample shows a robust hollow fibrous structure. With increasing SiO2 content, an increase at first and then a decrease in coercivity (Hc) and monotonously a decrease in saturation magnetization (Ms) have been determined in the obtained modified CoFe2O4 hollow nanofibers. A maximum Ms of about 80 emu g(-1) and a maximum Hc of about 1477 Oe could be, respectively, acquired from the pure CoFe2O4 nanorods and the modified CoFe2O4 hollow nanofibers with about 14.9% SiO2. The changes in Ms, Hc and the structure evolution mechanism of these SiO2-modified CoFe2O4 hollow nanofibers have been elaborated systematically. Furthermore, it is suggested that amorphous SiO2 enables effectively improving the structure endurance of 1D electrospun inorganic oxide hollow nanostructures being subjected to high temperatures.

  2. Contact lens trends over three decades in a hospital-based practice in India.

    Science.gov (United States)

    Rajan, Rajni; Mahadevan, Rajeswari; Thomas, Ann Mary; Bhattacharjee, Pradipta

    2017-09-26

    Contact lens fittings in a hospital-based practice are different from those in private practices because of specialised conditions. Few studies have been published on material preferences of such wearers, especially in long-term wearers. The aim of this study is to document contact lens prescribing trends in a hospital-based practice among long-term lens wearers and to identify their demographic profile. Subjects reporting to a contact lens clinic of a tertiary eye-care centre in India from 1 January 2014 to 31 December 2014, with a minimum of five years of lens wear, were included in the study. Data were collected retrospectively from the electronic medical charts of these subjects. Three hundred and sixty subjects were included in the study. The average duration of contact lens wear among the subjects was 9 ± 5 years (range: 5-35 years). The average age of the subjects was 31.38 ± 11.75 years (age range: 5-78 years). Hydrogel material and soft spherical type were preferred by most of the soft lens wearers (53 per cent). Eighty per cent of subjects followed hand hygiene and cleaning regimen practices. The preference for monthly replacement lenses and silicone hydrogel material increased over the years. Regular after-care consultations could enforce the need for compliance with hand hygiene and cleaning regimens among lens wearers. © 2017 Optometry Australia.

  3. Histochemical analysis of bandage contact lens precipitates.

    Science.gov (United States)

    Nessim, Maged; Pandey, Suresh K; Werner, Liliana; Mohammed, Musadiq; Kumar, Vinod

    2008-02-01

    Contact lens deposits have been reported previously with extended wear of soft contact lenses, with proteins, lipids, mucous, and various salts such as chloride, potassium and calcium being deposited on the lens surface [1]. We report an unusual case of precipitates on the surface of a bandage contact lens (BCL) following intensive treatment with topical preservative free artificial tears. Evaluation included microscopic and histochemical analysis of the BCL. We have also reviewed the literature for previous reports of contact lens precipitates.

  4. Magnetic and Optical Properties of Submicron-Size Hollow Spheres

    Directory of Open Access Journals (Sweden)

    Hirofumi Yoshikawa

    2010-02-01

    Full Text Available Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials, and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

  5. Luneburg modified lens for surface water waves

    Science.gov (United States)

    Pichard, Helene; Maurel, Agnes; Petitjeans, Phillipe; Martin, Paul; Pagneux, Vincent

    2015-11-01

    It is well known that when the waves pass across an elevated bathymetry, refraction often results in amplification of waves behind it. In this sense, focusing of liquid surface waves can be used to enhance the harvest efficiency of ocean power. An ocean wave focusing lens concentrates waves on a certain focal point by transforming straight crest lens of incident waves into circular ones just like an optical lens. These devices have attracted ocean engineers and are promising because they enable the effective utilization of wave energy, the remaining challenge being to increase the harvest efficiency of the lens. In this work, in order to improve well known focusing of surface liquid waves by lens, the propagation of liquid surface waves through a Luneburg modified lens is investigated. The traditional Luneburg lens is a rotationally symmetric lens with a spatially varying refractive-index profile that focuses an incident plane wave on the rim of the lens. The modified Luneburg lens allows to choose the position of the focal point, which can lie inside or outside the lens. This new degree of freedom leads to enhanced focusing and tunable focusing. The focusing of linear surface waves through this lens is investigated and is shown to be more efficient than classical profile lenses.

  6. A microcapillary lens for X-rays

    CERN Document Server

    Dudchik, Y I

    1999-01-01

    A new design of a compound refractive lens for X-rays is proposed. The lens is made as a set of glue microlenses placed in a glass capillary. The technique of lens fabrication is described. Results of ray tracing calculations for 8 and 15 keV photons are represented.

  7. Contact Lens-related Complications: A Review.

    Science.gov (United States)

    Alipour, Fateme; Khaheshi, Saeed; Soleimanzadeh, Mahya; Heidarzadeh, Somayeh; Heydarzadeh, Sepideh

    2017-01-01

    Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years.

  8. Contact lens-related complications: A review

    Directory of Open Access Journals (Sweden)

    Fateme Alipour

    2017-01-01

    Full Text Available Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years.

  9. Contact Lens-related Complications: A Review

    Science.gov (United States)

    Alipour, Fateme; Khaheshi, Saeed; Soleimanzadeh, Mahya; Heidarzadeh, Somayeh; Heydarzadeh, Sepideh

    2017-01-01

    Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years. PMID:28540012

  10. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  11. Professoren og Ålen

    DEFF Research Database (Denmark)

    Poulsen, Bo

    2016-01-01

    Biolog og havforsker Johannes Schmidt regnes for at være Danmarks mest betydningsfulde havforsker gennem tiderne. Hans mange forskningsbaserede jordomsejlinger bragte ham til eksotiske egne og til opdagelsen af adskillige nye dyrearter. Dog blev særligt ålen og dens gydepladser et hovedfokus...

  12. ECTOPIC LENS EXTRACTION IN CHILDREN

    Directory of Open Access Journals (Sweden)

    Vladimir Pfeifer

    2002-12-01

    Full Text Available Background. Ectopia lentis continues to be a therapeutic challenge for ophthalmologists. It can occur as an isolated condition, after ocular trauma, in association with other ocular disorders, as part of a systemic mesodermal disease or a complication of general metabolic disorders. Minimal subluxation of the lens may cause no visual symptoms, but in more advanced cases serious optical disturbances arise. The most important is amblyopia. Surgical treatment options include iris manipulation, lens discission, aspiration, intracapsular or extracapsular extraction, and pars plana lensectomy. The choice of surgical technique remains controversial, in part because of the historically poor visual results and high rate of perioperative complications, including vitreous loss and retinal detachment.Methods. We describe a surgical technique based on the use of the Cionni endocapsular tension ring, dry irrigation aspiration of lens material, centration of the capsular bag and foldable intraocular lens implantation into the bag. With mentioned surgical technique 8 patients were operated; 4 boys and 4 girls, together 11 eyes.Results. The final BCVA after follow up period improved in 9 eyes and it remained the same as before operation in one eye. Statistical comparison of preoperative and postoperative visual acuities showed significant improvement. On the other hand there was no correlation between preoperative and postoperative visual acuity.Conclusions. This surgical procedure is an alternative approach in solving this challenging cases of ectopia lentis with good postoperative visual rehabilitation.

  13. The Ultrawideband Leaky Lens Antenna

    NARCIS (Netherlands)

    Bruni, S.; Neto, A.; Marliani, F.

    2007-01-01

    A novel directive and nondispersive antenna is presented: the ultrawideband (UWB) leaky lens. It is based on the broad band Cherenkov radiation occurring at a slot printed between different infinite homogeneous dielectrics. The first part of the paper presents the antenna concept and the UWB design.

  14. A facile approach to synthesize SiO2 · Re2O3 (Re = Y, Eu, La, Sm, Tb, Pr) hollow sphere and its application in drug release

    Science.gov (United States)

    Li, Zhihua; Zhu, Lin; Liu, Qian; Du, Yu; Wang, Feng

    2013-10-01

    Multifunctional SiO2 · Re2O3 (Re = Y, Eu, La, Sm, Tb, Pr) hollow spheres (HSs) have been fabricated using an acidic Re3+ ion solution. Under ultraviolet radiation, functional HSs emit different colors of light according to the different rare-earth ions embedded into the shell of SiO2 hollow spheres. The as-prepared hollow capsules were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Brunauer-Emmett-Teller method, scanning electron microscopy, and energy-dispersive spectrometry. Drug loading and release experiments have been carried out using SiO2 · Eu2O3 HSs that acted as drug carriers. The results demonstrate that the multifunctional HSs exhibit a high storage capacity and the ability of retaining drug stability and activity, which indicates that the as-synthesized fluorescent hollow capsules are a potential candidate as drug delivery materials.

  15. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator.

    Science.gov (United States)

    Gessner, Spencer; Adli, Erik; Allen, James M; An, Weiming; Clarke, Christine I; Clayton, Chris E; Corde, Sebastien; Delahaye, J P; Frederico, Joel; Green, Selina Z; Hast, Carsten; Hogan, Mark J; Joshi, Chan; Lindstrøm, Carl A; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A; Mori, Warren B; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m(-1) is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  16. Synthesis of hollow Cu1.8S nano-cubes for electromagnetic interference shielding.

    Science.gov (United States)

    Jiang, Wanchun; Wu, Fan; Jiang, Yijun; Sun, Mengxiao; Zhang, Kun; Xia, Yilu; Wang, Derong; Xie, Aming

    2017-08-03

    The applications of inorganic semiconductor nano-structures as electromagnetic interference (EMI) shielding materials have been scarcely researched. Herein, we have designed hollow Cu1.8S nano-cubes via a mild anion exchange and etching process. These 30 wt% hollow Cu1.8S nano-cubes loaded in wax can display 30 dB of EMI shielding effectiveness (SE) in the whole tested frequency range of 2-18 GHz with a sample thickness of only 1 mm. This good EMI shielding performance can be attributed to the high electric conductivity, which leads to a high dielectric constant. This research opens up the possibility for the applications of inorganic semiconductor nano-structures as lightweight EMI shielding materials, especially in the areas of aerospace, automobile and sophisticated electronics.

  17. Electrochemically Active Polymeric Hollow Fibers based on Poly(ether- b -amide)/Carbon Nanotubes

    KAUST Repository

    Cuevas, Carolina

    2017-09-18

    A simple and effective method to incorporate catalytic activity to a hollow fiber membrane is reported. Polyetherimide hollow fiber membranes were coated with a solution containing carboxyl-functionalized multi-walled carbon nanotubes and poly(ether-b-amide). Electron microscopy images confirmed the presence of a layer of percolating carbon nanotubes on the surface of the membranes. Cyclic voltammetry and linear swept voltammetry experiments showed that these membranes are able to drive the reactions of hydrogen evolution, and oxygen reduction, making them a cheaper, and greener substitute for platinum based cathodes in microbial bioelectrochemical systems. Water flux and molecular weight cut off experiments indicated that the electrochemically active coating layer does not affect the ultrafiltration performance of the membrane.

  18. Biomolecule-assisted hydrothermal synthesis and properties of manganese sulfide hollow microspheres

    Science.gov (United States)

    Ma, Wei; Chen, Gen; Zhang, Dan; Zhou, Kechao; Qiu, Guanzhou; Liu, Xiaohe

    2012-11-01

    Gamma-manganese sulfide (γ-MnS) hollow microspheres have been successfully synthesized via a biomolecule-assisted hydrothermal process in the presence of L-cysteine and urea at 180 °C for 24 h. In the synthesis system, L-cysteine was employed as not only a sulfur source, but also a coordination agent. The structure, morphology and optical properties of as-prepared products have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and photoluminescence (PL) spectrum. Reaction parameters such as ratio of L-cysteine to urea, surfactants and reaction time played a significant role in controlling the morphology of as-prepared products. The probable formation mechanism of the γ-MnS hollow microsphere was proposed on the basis of the experimental results.

  19. Cu20Si12: A Hollow Cage Constituted of a Copper Dodecahedron and a Silicon Icosahedron.

    Science.gov (United States)

    Zhao, Hui-Yan; Wang, Jing; Ai, Ling-Yan; Liu, Ying

    2016-08-11

    A stable hollow copper silicide cage with Ih symmetry, Cu20Si12, constituted of a copper dodecahedron and a silicon icosahedron, was investigated using density functional theory. Molecular dynamics simulations show that Cu20Si12 retains its geometric topology up to an effective temperature of about 962 K. The molecule has a HOMO-LUMO gap of 1.099 eV, indicating its relatively high chemical stability. These frontier molecular orbitals show clear characteristics of hybridization between Si 3p and Cu 3d electrons. This proposed structure helps to extend the range of high-symmetry molecular polyhedral species. The hollow space within Cu20Si12 can be used to accommodate other atoms or molecules and emphasizes the benefit of studying endohedral fullerenes.

  20. Fabrication of carbon nanotube-polyimide composite hollow microneedles for transdermal drug delivery.

    Science.gov (United States)

    Lyon, Bradley J; Aria, Adrianus I; Gharib, Morteza

    2014-12-01

    We introduce a novel method for fabricating hollow microneedles for transdermal drug delivery using a composite of vertically-aligned carbon nanotubes and polyimide. Patterned bundles of carbon nanotubes are used as a porous scaffold for defining the microneedle geometry. Polyimide resin is wicked through the carbon nanotube scaffold to reinforce the structure and provide the prerequisite strength for achieving skin penetration. The high aspect ratio and bottom-up assembly of carbon nanotubes allow the structure of the microneedles to be created in a single step of nanotube fabrication, providing a simple, scalable method for producing hollow microneedles. To demonstrate the utility of these microneedles, liquid delivery experiments are performed. Successful delivery of aqueous methylene blue dye into both hydrogel and swine skin in vitro is demonstrated. Electron microscopy images of the microneedles taken after delivery confirm that the microneedles do not sustain any structural damage during the delivery process.

  1. Tube entrance lens focus control

    Science.gov (United States)

    Weisser, D. C.; Fifield, L. K.; Kitchen, T. F. G.; Tunningley, T. B.; Lobanov, N. R.; Muirhead, A. G.

    2013-02-01

    The entrance of the accelerator tube in a large electrostatic accelerator imposes a strong lens that dominates the beam optics. The magnification of the lens is large because of the low injection energy, the high voltage gradient of the acceleration tube and the long distance to the terminal. In the absence of the acceleration, the magnification would produce an unacceptably large beam spot at the terminal. The tyranny of the lens is especially irksome when the accelerator is required to operate at a lower terminal voltage than the one corresponding to the nominal gradient at high voltage. One way around the difficulty, used in NEC Pelletron accelerators, is to insert a series of nylon and steel rods that short together units of the acceleration structure at the terminal leaving the ones near the entrance close to the nominal gradient for optimum transmission. This operation takes time and risks the loss of insulating gas. Another alternative used in the 25URC at Oak Ridge National Laboratory, is to focus the beam at the tube entrance, substantially diluting the effect of the entrance lens. The beam then diverges and so requires an additional lens part way to the terminal. This solution is only partially effective and still necessitates use of shorting rods for low voltage operation. The fact that these elaborate strategies are used is evidence that the alternative of lowering the injection energy as the terminal voltage is lowered imposes enough problems that it is not used in practice. We have modeled a solution that controls the voltage gradient at the tube entrance using an external power supply. This not only maintains the focusing effect of the lens but provides the opportunity to tune the beam by adjusting the entrance lens. A 150 kV power supply outside the pressure vessel feeds a controllable voltage through a high voltage feed-through to the fifth electrode of the accelerator tube. Thus 150 kV on this electrode creates the nominal gradient of 30 kV per

  2. Multifocal contact lens myopia control.

    Science.gov (United States)

    Walline, Jeffrey J; Greiner, Katie L; McVey, M Elizabeth; Jones-Jordan, Lisa A

    2013-11-01

    Previous studies on soft multifocal contact lens myopia control published in the peer-reviewed literature reported findings of noncommercial contact lenses worn for 1 year or less. This study sought to determine the progression of myopia and axial elongation of children fitted with commercially available distance center soft multifocal contact lenses for 2 years. Eight- to eleven-year-old children with -1.00 D to -6.00 D spherical component and less than 1.00 D astigmatism were fitted with soft multifocal contact lenses with a +2.00 D add (Proclear Multifocal "D"; CooperVision, Fairport, NY). They were age- and gender-matched to participants from a previous study who were fitted with single-vision contact lenses (1 Day Acuvue; Vistakon, Jacksonville, FL). A-scan ultrasound and cycloplegic autorefraction were performed at baseline, after 1 year, and after 2 years. Multilevel modeling was used to compare the rate of change of myopia and axial length between single-vision and soft multifocal contact lens wearers. Forty participants were fitted with soft multifocal contact lenses, and 13 did not contribute complete data (5 contributed 1 year of data). The adjusted mean ± standard error spherical equivalent progression of myopia at 2 years was -1.03 ± 0.06 D for the single-vision contact lens wearers and -0.51 ± 0.06 for the soft multifocal contact lens wearers (p < 0.0001). The adjusted mean axial elongation was 0.41 ± 0.03 and 0.29 ± 0.03 for the single-vision and soft multifocal contact lens wearers, respectively (p < 0.0016). Soft multifocal contact lens wear resulted in a 50% reduction in the progression of myopia and a 29% reduction in axial elongation during the 2-year treatment period compared to a historical control group. Results from this and other investigations indicate a need for a long-term randomized clinical trial to investigate the potential for soft multifocal contact lens myopia control.

  3. Facile Synthesis of Rambutan-Like ZnO Hierarchical Hollow Microspheres with Highly Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Ke-Jian Ju

    2015-01-01

    Full Text Available Rambutan-like ZnO hierarchical hollow microspheres (ZnO HHMs were constructed under hydrothermal conditions, using carboxyl methyl starch (CMS as a soft template. The resulting products were characterized by using X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The experimental parameters and growth mechanism of rambutan-like ZnO HHMs were discussed in some detail. The as-prepared samples displayed improved photocatalytic activity for the degradation of rhodamine B under ultraviolet (UV irradiation.

  4. Impact of soft contact lens edge design and midperipheral lens shape on the epithelium and its indentation with lens mobility.

    Science.gov (United States)

    Wolffsohn, James S; Drew, Thomas; Dhallu, Sandeep; Sheppard, Amy; Hofmann, Greg J; Prince, Mark

    2013-09-11

    To evaluate the influence of soft contact lens midperipheral shape profile and edge design on the apparent epithelial thickness and indentation of the ocular surface with lens movement. Four soft contact lens designs comprising of two different plano midperipheral shape profiles and two edge designs (chiseled and knife edge) of silicone-hydrogel material were examined in 26 subjects aged 24.7 ± 4.6 years, each worn bilaterally in randomized order. Lens movement was imaged enface on insertion, at 2 and 4 hours with a high-speed, high-resolution camera simultaneous to the cross-section of the edge of the contact lens interaction with the ocular surface captured using optical coherence tomography (OCT) nasally, temporally, and inferiorly. Optical imaging distortions were individually corrected for by imaging the apparent distortion of a glass slide surface by the removed lens. Apparent epithelial thickness varied with edge position (P design. Horizontal and vertical lens movement did not change with time postinsertion. Vertical motion was affected by midperipheral lens shape profile (P design (P designs. Dynamic OCT coupled with high-resolution video demonstrated that soft contact lens movement and image-corrected ocular surface indentation were influenced by both lens edge design and midperipheral lens shape profiles.

  5. Lens stem cells may reside outside the lens capsule: an hypothesis

    Directory of Open Access Journals (Sweden)

    Meyer Rita A

    2007-06-01

    Full Text Available Abstract In this paper, we consider the ocular lens in the context of contemporary developments in biological ideas. We attempt to reconcile lens biology with stem cell concepts and a dearth of lens tumors. Historically, the lens has been viewed as a closed system, in which cells at the periphery of the lens epithelium differentiate into fiber cells. Theoretical considerations led us to question whether the intracapsular lens is indeed self-contained. Since stem cells generate tumors and the lens does not naturally develop tumors, we reasoned that lens stem cells may not be present within the capsule. We hypothesize that lens stem cells reside outside the lens capsule, in the nearby ciliary body. Our ideas challenge the existing lens biology paradigm. We begin our discussion with lens background information, in order to describe our lens stem cell hypothesis in the context of published data. Then we present the ciliary body as a possible source for lens stem cells, and conclude by comparing the ocular lens with the corneal epithelium.

  6. MnO{sub 2}-wrapped hollow graphitized carbon nanosphere electrode for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Jing; Yang, Xing; Zhou, Haiyan; Kang, Liping; Lei, Zhibin [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710062 (China); School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062 (China); Liu, Zong-Huai, E-mail: zhliu@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710062 (China); School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062 (China)

    2016-01-15

    Highlights: • MnO{sub 2}/HGC nanospheres are prepared by a cooperative template wrapping method. • MnO{sub 2}/HGC nanospheres possess large specific surface area. • MnO{sub 2}/HGC nanospheres are benefit for transmission of ions and electrons. • MnO{sub 2}/HGC electrodes exhibit a high specific capacitance. - Abstract: MnO{sub 2}-wrapped hollow graphitized carbon nanospheres (MnO{sub 2}/HGC) electrodes are prepared by a cooperative template wrapping method. hollow Graphitized carbon nanospheres (HGC) are firstly obtained by carbonizing phenolic resin followed by etching the SiO{sub 2} template, then the MnO{sub 2} ultrathin nanoplates are coated on the surfaces of the HGC nanospheres through a redox reaction between KMnO{sub 4} and HGC nanospheres. The as-prepared MnO{sub 2}/HGC hollow nanospheres possess porous structure and large specific surface area (∼230 m{sup 2} g{sup −1}). The specific capacitances of MnO{sub 2}/HGC nanosphere electrodes with different mass ratios of MnO{sub 2} to HGC are about 340–380 F g{sup −1} at a scan rate of 5 mV s{sup −1} in Na{sub 2}SO{sub 4} solution, and shows relative good cycling performance of the initial capacitance after 1000 cycles. The good specific capacitance is ascribed to the novel hollow nanosphere structure, which possesses high surface-to-volume ratio, and makes it easy for the mass diffusion of electrolyte and transmission of ions and electrons and also maintains the mechanical integrality.

  7. Fabrication of polycrystalline diamond refractive X-ray lens by femtosecond laser processing

    Energy Technology Data Exchange (ETDEWEB)

    Kononenko, T.V.; Ralchenko, V.G.; Ashkinazi, E.E.; Konov, V.I. [General Physics Institute of Russian Academy of Sciences, Moscow (Russian Federation); National Research Nuclear University ' ' MEPhI' ' , Moscow (Russian Federation); Polikarpov, M.; Ershov, P. [Immanuel Kant Baltic Federal University, Functional Nanomaterials, Kaliningrad (Russian Federation); Kuznetsov, S.; Yunkin, V. [Institute of Microelectronics Technology RAS, Chernogolovka, Moscow region (Russian Federation); Snigireva, I. [European Synchrotron Radiation Facility, Grenoble (France)

    2016-03-15

    X-ray planar compound refractive lenses were fabricated from a polycrystalline diamond plate grown by chemical vapor deposition, by precise through cutting with femtosecond laser pulses. The lens geometry and the surface morphology were investigated with optical and scanning electron microscopy, while the material structure modification was analyzed by Raman spectroscopy. The results of the preliminary lens test at 9.25-keV X-rays are presented. (orig.)

  8. Modern lens antennas for communications engineering

    CERN Document Server

    Thornton, John

    2012-01-01

    The aim of this book is to present the modern design principles and analysis of lens antennas. It gives graduates and RF/Microwave professionals the design insights in order to make full use of lens antennas.  Why do we want to write a book in lens antennas? Because this topic has not been thoroughly publicized, its importance is underestimated. As antennas play a key role in communication systems, recent development in wireless communications would indeed benefit from the characteristics of lens antennas: low profile, and low cost etc.  The major advantages of lens antennas are na

  9. Design and fabrication of Ni nanowires having periodically hollow nanostructures

    Science.gov (United States)

    Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2014-09-01

    interior surfaces of AAO. The Ni shell layer allows the Ni segments to remain even after dissolution of the Ag segments. Because the electroplating conditions can be easily controlled, we could carefully adjust the size and pitch of the periodically hollow nanospaces. We also describe a method for the fabrication of Ni nanorods by forming an Ag shell instead of a Ni shell on the Ni-Ag barcode nanowire, in which the interior of the AAO surfaces was modified with a compound bearing a thiol group prior to electroplating. Electronic supplementary information (ESI) available: Information on the current profile during pulsed-electroplating, the histogram for the Ni and nanopores, and STEM images of obtained nanowires. See DOI: 10.1039/c4nr02625j

  10. Spectral Clustering of Hermean craters hollows

    Science.gov (United States)

    Lucchetti, Alice; Pajola, Maurizio; Cremonese, Gabriele; Carli, Cristian; Marzo, Giuseppe; Roush, Ted

    2017-04-01

    The Mercury Dual Imaging System (MDIS, Hawkins et al., 2007) onboard NASA MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, provided high-resolution images of "hollows", i.e. shallow, irregular, rimless, flat-floored depressions with bright interiors and halos, often found on crater walls, rims, floors and central peaks (Blewett et al., 2011, 2013). The formation mechanism of these features was suggested to be related to the depletion of subsurface volatiles (Blewett et al., 2011, Vaughan et al., 2012). To understand the hollows' mineralogical composition, which can provide new insights on Mercury's surface characterization, we applied a spectral clustering method to different craters where hollows are present. We chose, as first test case, the 20 km wide Dominici crater due to previous multiple spectral detection (Vilas et al., 2016). We used the MDIS WAC dataset covering Dominici crater with a scale of 935 m/pixel through eight filters, ranging from 0.433 to 0.996 μm. First, the images have been photometrically corrected using the Hapke parameters (Hapke et al., 2002) derived in Domingue et al. (2015). We then applied a statistical clustering over the entire dataset based on a K-means partitioning algorithm (Marzo et al., 2006). This approach was developed and evaluated by Marzo et al. (2006, 2008, 2009) and makes use of the Calinski and Harabasz criterion (Calinski, T., Harabasz, J., 1974) to identify the intrinsically natural number of clusters, making the process unsupervised. The natural number of ten clusters was identified and spectrally separates the Dominici surrounding terrains from its interior, as well as the two hollows from their edges. The units located on the brightest part of the south wall/rim of Dominici crater clearly present a wide absorption band between 0.558 and 0.828 μm. Hollows surrounding terrains typically present a red slope in the VNIR with a possible weak absorption band centered at 0.748

  11. Conjunctival impression cytology in contact lens wearers.

    Directory of Open Access Journals (Sweden)

    Simon Priya

    2002-01-01

    Full Text Available PURPOSE: To evaluate the cytological changes in conjunctiva following regular contact lens wear and to determine the correlation, if any, between severity of cytological alteration and symptoms related to contact lens wear. METHODS: One hundred eyes (50 normal asymptomatic subjects who served as a control group were studied by conjunctival impression cytology (CIC. These subjects were fitted with rigid gas permeable (RGP or soft contact lenses and were followed up at the end of 3 and 6 months. At each follow-up visit the CIC was repeated. A filter paper with the impression specimen was stained with periodic acid schiff (PAS and haematoxylin stain to study goblet cell loss. Papanicolaou stain was done to study squamous metaplasia. The cytological changes were graded using the system described by Natadisastra et al. RESULTS: Severity of cytological changes increased with the duration of contact lens wear (P = 0.00001. At the end of 6 months, 60% of symptomatic eyes wearing soft contact lens and RGP lens showed abnormal CIC changes. None of the asymptomatic RGP contact lens wearing eyes showed abnormal CIC changes whereas 33.4% of the asymptomatic soft contact lens wearing eyes showed abnormal CIC changes (P = 0.033. Epithelial changes occurred within 3-6 months of contact lens fitting. CONCLUSION: Severity of cytological changes increased with duration of lens wear (P = 0.00001. Prevalence and severity of cytological alteration is more in symptomatic contact lens wearers. Soft contact lens wearers although asymptomatic showed severe CIC changes.

  12. Hollow-Fiber Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  13. Life Cycle Tests on a Hollow Cathode Based Plasma Contactor

    Science.gov (United States)

    Vaughn, Jason A.; Schneider, Todd A.; Munafo, Paul (Technical Monitor)

    2001-01-01

    The propulsive Small Expendable Deployer System (ProSEDS) mission is designed to provide an on-orbit demonstration of the electrodynamic propulsion capabilities of tethers in space. The ProSEDS experiment will be a secondary payload on a Delta II unmanned expendable booster with a mission duration of 12 days. A 5-km conductive tether is attached to the Delta II second stage and collects current from the low Earth orbit (LEO) plasma, and a Hollow Cathode Plasma Contactor (HCPC) emits the collected electrons from the Delta II, completing the electrical circuit to the ambient plasma. The HCPC for the ProSEDS mission have made it necessary to turn off the HCPC once a minute throughout the entire mission. Because of the unusual operating requirements by the ProSEDS mission, an engineering development unit of the HCPC was built to demonstrate the HCPC design would start reliably for the life of the ProSEDS mission. During the life test the engineering unit cycled for over 10,000 on/off cycles without missing a single start, and during that same test the HCPC unit demonstrated the capability to emit 0 to 5 A electron emission current. The performance of the HCPC unit during this life test will be discussed.

  14. Investigation on raspberry-like magnetic-hollow silica nanospheres and its preliminary application for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunlei; Yan, Juntao, E-mail: yanjuntaonihao@163.com [Wuhan Polytechnic University, College of Chemistry and Environmental Engineering (China); Li, Zhanfeng; Wang, Hongyan; Cui, Xuejun [Jilin University, College of Chemistry (China)

    2013-09-15

    A series of raspberry-like magnetic-hollow silica nanospheres were successfully synthesized via the sol-gel process, which was based on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene. The Fe{sub 3}O{sub 4}@SiO{sub 2} particles as the outer shell were compactly assembled on the surface of PS, and then magnetic-hollow nanospheres were obtained by calcination. Different synthesis conditions including the amount of NH{sub 4}OH, TEOS, Fe{sub 3}O{sub 4}, and the adding time of PS were systematically investigated to discuss the influence of these conditions on the morphology and structure. The prepared magnetic-hollow nanospheres were systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectrometry, energy-dispersive X-ray analysis, thermogravimetric analysis and nitrogen adsorption-desorption measurement. SEM and TEM images exhibited that the obtained samples with the perfect spherical profile and large cavities structure were well monodisperse and uniform under the optimized condition. Zeta-potential analysis was employed to make clear the formation mechanism of raspberry-like PS@Fe{sub 3}O{sub 4}@SiO{sub 2} composite nanosphere. Moreover, the drug release of ibuprofen experiment results demonstrated that the magnetic-hollow nanospheres could be used as a drug carrier to slowly release and deliver drugs.

  15. Direct synthesis of solid and hollow carbon nanospheres over NaCl crystals using acetylene by chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chandra Kishore, S.; Anandhakumar, S.; Sasidharan, M., E-mail: sasidharan.m@res.srmuniv.ac.in

    2017-04-01

    Highlights: • Hollow and solid carbon nanospheres were synthesized by CVD method. • NaCl was used as template for direct growth of carbon nanospheres. • Separation of NaCl from the mixture is made easy by dissolving in water. • The hollow carbon nanospheres exhibit high specific capacity in Li-ion batteries than the graphite anodes. - Abstract: Carbon nanospheres (CNS) with hollow and solid morphologies have been synthesised by a simple chemical vapour deposition method using acetylene as a carbon precursor. Sodium chloride (NaCl) powder as a template was used for the direct growth of CNS via facile and low-cost approach. The effect of various temperatures (500 °C, 600 °C and 700 °C) and acetylene flow rates were investigated to study the structural evolution on the carbon products. The purified CNS thus obtained was characterized by various physicochemical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and cyclicvoltametry. The synthesised hollow nanospheres were investigated as anode materials for Li-ion batteries. After 25 cycles of repeated charge/discharge cycles, the discharge and charge capacities were found to be 574 mAh/g and 570 mAh/g, respectively which are significantly higher than the commercial graphite samples.

  16. Casting of particle-based hollow shapes

    Science.gov (United States)

    Menchhofer, Paul

    1995-01-01

    A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product.

  17. Porous-wall hollow glass microspheres as carriers for biomolecules

    Science.gov (United States)

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  18. Wet spinning of asymmetric hollow fibre membranes for gas separation

    NARCIS (Netherlands)

    van 't Hof, Jacob Adriaan

    1988-01-01

    This thesis describes the spinning and characterizatin of hollow fibre membranes for gas separation. The type of fibres studied here are made by a wet spinning process. A homogeneous solution is prepared, consisting of a polymer in a suitable organic solvent, and extruded as a hollow fibre. Both the

  19. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material

    Directory of Open Access Journals (Sweden)

    Bidhan Shrestha

    2015-01-01

    Full Text Available Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  20. optimizing compression zone of flanged hollow cored concrete ...

    African Journals Online (AJOL)

    eobe

    effective flange width and the hollow core position in the compression zone of a plain concrete beam with a point loaded at .... OPTIMIZING COMPRESSION ZONE OF FLANGED HOLLOW CORED CONCRETE BEAMS USING MOMENT OF INERTIA THEORY, ... chi-square test, a correction factor was obtained using.

  1. Safety of carbon fibre reinforced plastic hollow sections in ...

    African Journals Online (AJOL)

    The use of steel hollow sections as compression members in structures has been a common practice. This study highlights the safety of using Carbon Fibre Reinforced Plastic (CFRP) hollow sections as compression structural members. The primary compression members in structures are columns and this study uses Finite ...

  2. Surface Charging Controlling of the Chinese Space Station with Hollow Cathode Plasma Contactor

    Science.gov (United States)

    Jiang, Kai; Wang, Xianrong; Qin, Xiaogang; Yang, Shengsheng; Yang, Wei; Zhao, Chengxuan; Chen, Yifeng; Shi, Liang; Tang, Daotan; Xie, Kan

    2016-07-01

    A highly charged manned spacecraft threatens the life of an astronaut and extravehicular activity, which can be effectively reduced by controlling the spacecraft surface charging. In this article, the controlling of surface charging on Chinese Space Station (CSS) is investigated, and a method to reduce the negative potential to the CSS is the emission electron with a hollow cathode plasma contactor. The analysis is obtained that the high voltage (HV) solar array of the CSS collecting electron current can reach 4.5 A, which can be eliminated by emitting an adequate electron current on the CSS. The theoretical analysis and experimental results are addressed, when the minimum xenon flow rate of the hollow cathode is 4.0 sccm, the emission electron current can neutralize the collected electron current, which ensures that the potential of the CSS can be controlled in a range of less than 21 V, satisfied with safety voltage. The results can provide a significant reference value to define a flow rate to the potential controlling programme for CSS.

  3. Template Free Synthesis of Hollow Ball-Like Nano-Fe2O3 and Its Application to the Detection of Dimethyl Methylphosphonate at Room Temperature

    Directory of Open Access Journals (Sweden)

    Guang Li

    2012-04-01

    Full Text Available This paper is focused on the template-free synthesis of nanosized ferric oxide (nano-Fe2O3 and its application in quartz crystal microbalance (QCM resonators to detect dimethyl methylphosphonate (DMMP, a simulant of Sarin. The X-ray diffraction (XRD patterns confirm that the synthesized samples are made of Fe2O3 and the scanning electron microscopy (SEM pictures show that the samples have ball-like shapes. The DMMP sensors with a sensing film of hollow ball-like and solid ball-like Fe2O3 are fabricated and their sensing characteristics are compared. The sensitivity of the hollow ball-like Fe2O3 sensor is more than 500% higher than the one of the solid ball-like Fe2O3 sensor. The hollow ball-like nano-Fe2O3 can be synthesized by a novel low temperature hydrothermal method. The sensors with the hollow ball-like Fe2O3 film perform well in a range of 1 to 6 ppm, with a sensitivity of 29 Hz/ppm at room temperature, while the appropriate recoverability and selectivity are maintained. In addition, the performance of different thicknesses of the sensing film of the hollow ball-like nano-Fe2O3 is investigated and the optimized relative film thickness of the hollow ball-like nano-Fe2O3 is found to be 20 μg/mm2.

  4. Modeling the evaporation of a pre-lens tear film on a contact lens

    Science.gov (United States)

    Anderson, Daniel; Talbott, Kevin; Xu, Amber; Seshaiyer, Padmanabhan

    2011-11-01

    We develop a model for evaporation of a post-blink pre-lens tear film in the presence of a porous contact lens. The tear film is modeled as a Newtonian fluid and the flow in the contact lens is assumed to obey Darcy's law. The evaporation model treats the contact lens as a wetting surface. Evaporative mass flux thins the pre-lens film down to a nonzero steady thickness at which point evaporation continues by drawing fluid up through the contact lens. Both one and two-dimensional models are explored. The post-lens film (between the contact lens and the corneal surface) is not included explicitly in the model but is assumed to act as a reservoir that supplies fluid drawn up through the contact lens. Supported by NSF CSUMS and REU programs.

  5. A 200 W Hall thruster with hollow indented anode

    Science.gov (United States)

    Ding, Yongjie; Sun, Hezhi; Wei, Liqiu; Li, Peng; Su, Hongbo; Peng, Wuji; Yu, Daren

    2017-10-01

    A hollow indented anode is proposed for increasing the neutral gas density in a discharge channel, in order to improve the performance of the thruster. The experimental results show that a hollow indented anode structure can effectively improve the performance, compared to a hollow straight anode under similar operating conditions, in terms of thrust, propellant utilization, ionization rate, and anode efficiency. Furthermore, simulations show that the indented anode can effectively increase the neutral gas density in a discharge channel and on the centerline of the channel, compared to a hollow straight anode. In addition, it can increase the ionization rate in the channel and the pre-ionization in the anode. Therefore, the hollow indented anode could be considered as an important design idea for improving thruster performance.

  6. Hollow fiber bioreactor technology for tissue engineering applications.

    Science.gov (United States)

    Eghbali, Hadis; Nava, Michele M; Mohebbi-Kalhori, Davod; Raimondi, Manuela T

    2016-01-01

    Hollow fiber bioreactors are the focus of scientific research aiming to mimic physiological vascular networks and engineer organs and tissues in vitro. The reason for this lies in the interesting features of this bioreactor type, including excellent mass transport properties. Indeed, hollow fiber bioreactors allow limitations to be overcome in nutrient transport by diffusion, which is often an obstacle to engineer sizable constructs in vitro. This work reviews the existing literature relevant to hollow fiber bioreactors in organ and tissue engineering applications. To this purpose, we first classify the hollow fiber bioreactors into 2 categories: cylindrical and rectangular. For each category, we summarize their main applications both at the tissue and at the organ level, focusing on experimental models and computational studies as predictive tools for designing innovative, dynamic culture systems. Finally, we discuss future perspectives on hollow fiber bioreactors as in vitro models for tissue and organ engineering applications.

  7. Self-templated chemically stable hollow spherical covalent organic framework

    Science.gov (United States)

    Kandambeth, Sharath; Venkatesh, V.; Shinde, Digambar B.; Kumari, Sushma; Halder, Arjun; Verma, Sandeep; Banerjee, Rahul

    2015-04-01

    Covalent organic frameworks are a family of crystalline porous materials with promising applications. Although active research on the design and synthesis of covalent organic frameworks has been ongoing for almost a decade, the mechanisms of formation of covalent organic frameworks crystallites remain poorly understood. Here we report the synthesis of a hollow spherical covalent organic framework with mesoporous walls in a single-step template-free method. A detailed time-dependent study of hollow sphere formation reveals that an inside-out Ostwald ripening process is responsible for the hollow sphere formation. The synthesized covalent organic framework hollow spheres are highly porous (surface area ~1,500 m2 g-1), crystalline and chemically stable, due to the presence of strong intramolecular hydrogen bonding. These mesoporous hollow sphere covalent organic frameworks are used for a trypsin immobilization study, which shows an uptake of 15.5 μmol g-1 of trypsin.

  8. Long-term evaluation of hollow screw and hollow cylinder dental implants : Clinical and radiographic results after 10 years

    NARCIS (Netherlands)

    Telleman, Gerdien; Meijer, Henny J. A.; Raghoebar, Gerry M.

    Background: In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and

  9. Fabricating customized hydrogel contact lens

    OpenAIRE

    Andre Childs; Hao Li; Daniella M. Lewittes; Biqin Dong; Wenzhong Liu; Xiao Shu; Cheng Sun; Zhang, Hao F.

    2016-01-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spe...

  10. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  11. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    Science.gov (United States)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  12. Hollow Pollen Shells to Enhance Drug Delivery

    Science.gov (United States)

    Diego-Taboada, Alberto; Beckett, Stephen T.; Atkin, Stephen L.; Mackenzie, Grahame

    2014-01-01

    Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

  13. CONTACT LENS RELATED CORNEAL ULCER

    Directory of Open Access Journals (Sweden)

    AGARWAL P

    2010-01-01

    Full Text Available A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are:overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. The presenting symptoms of contact lens related corneal ulcers include eye discomfort, foreign body sensation and lacrimation. More serious symptoms are redness (especially circum-corneal injection, severe pain, photophobia, eye discharge and blurring of vision. The diagnosis is established by a thorough slit lamp microscopic examination with fluorescein staining and corneal scraping for Gram stain and culture of the infective organism. Delay in diagnosing and treatment can cause permanent blindness, therefore an early referral to ophthalmologist and commencing of antimicrobial therapy can prevent visual loss.

  14. Three-dimensional interconnected nickel phosphide networks with hollow microstructures and desulfurization performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuna, E-mail: zhangshujuan@tust.edu.cn [College of Textile Engineering, Zhejiang Industry Polytechnic College, Shaoxing 312000 (China); Zhang, Shujuan [College of Science, Tianjin University of Science and Technology, Tianjin 300457 (China); Song, Limin, E-mail: tjpu2012@sohu.com [College of Environment and Chemical Engineering and State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Wu, Xiaoqing [Institute of Composite Materials and Ministry of Education Key Laboratory of Advanced Textile Composite Materials, Tianjin Polytechnic University, Tianjin 300387 (China); Fang, Sheng, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering and State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China)

    2014-05-01

    Graphical abstract: Three-dimensional interconnected nickel phosphide networks with hollow microstructures and desulfurization performance. - Highlights: • Three-dimensional Ni{sub 2}P has been prepared using foam nickel as a template. • The microstructures interconnected and formed sponge-like porous networks. • Three-dimensional Ni{sub 2}P shows superior hydrodesulfurization activity. - Abstract: Three-dimensional microstructured nickel phosphide (Ni{sub 2}P) was fabricated by the reaction between foam nickel (Ni) and phosphorus red. The as-prepared Ni{sub 2}P samples, as interconnected networks, maintained the original mesh structure of foamed nickel. The crystal structure and morphology of the as-synthesized Ni{sub 2}P were characterized by X-ray diffraction, scanning electron microscopy, automatic mercury porosimetry and X-ray photoelectron spectroscopy. The SEM study showed adjacent hollow branches were mutually interconnected to form sponge-like networks. The investigation on pore structure provided detailed information for the hollow microstructures. The growth mechanism for the three-dimensionally structured Ni{sub 2}P was postulated and discussed in detail. To investigate its catalytic properties, SiO{sub 2} supported three-dimensional Ni{sub 2}P was prepared successfully and evaluated for the hydrodesulfurization (HDS) of dibenzothiophene (DBT). DBT molecules were mostly hydrogenated and then desulfurized by Ni{sub 2}P/SiO{sub 2}.

  15. Nanowire networks and hollow nanospheres of Ag-Au bimetallic alloys at room temperature

    Science.gov (United States)

    Britto Hurtado, R.; Cortez-Valadez, M.; Arizpe-Chávez, H.; Flores-Lopez, N. S.; Álvarez, Ramón A. B.; Flores-Acosta, M.

    2017-03-01

    Due to their physicochemical properties, metallic nanoalloys have potential applications in biomedicine, electrocatalysis and electrochemical sensors, among many other fields. New alternative procedures have emerged in order to reduce production costs and the use of toxic substances. In this study we present a novel low-toxicity synthesis method for the fabrication of nanowire networks (NWNs) and Ag-Au hollow nanospheres. The synthesis process is performed at room temperature without any sophisticated equipment, such as special cameras or furnaces, etc. Transmission electron microscopy showed that the NWNs contain random alloys with a diameter of between 10-13 nm. The radius for the hollow nanospheres is approximately located between 70-130 nm. The absorption bands in the UV-vis spectrum associated with the surface plasmon in Ag-Au bimetallic nanoparticles are highlighted at 385 nm for the NWNs and 643 nm for the hollow nanospheres. The study was performed with low-toxicity substances, such as rongalite, ascorbic acid and sucrose, and showed high efficiency for the fabrication of these types of nanostructures, as well as good stability for long periods of time.

  16. Synthesis, morphology and optical properties of pure and Eu{sup 3+} doped β-Ga{sub 2}O{sub 3} hollow nanostructures by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Kang, B.K. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Mang, S.R. [SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lim, H.D.; Song, K.M.; Song, Y.H. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Go, D.H.; Jung, M.K. [Hyosung Corporation, R and D Business Labs, Anyang 431-080 (Korea, Republic of); Senthil, K. [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Yoon, D.H., E-mail: dhyoon@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-09-15

    Pure and Eu{sup 3+} doped β-Ga{sub 2}O{sub 3} hollow nanostructures were synthesized by hydrothermal and calcination processes using carbon spheres as templates in ethanol–water solution. Field-emission scanning electron microscopy and high-resolution transmission electron microscopy analysis revealed β-Ga{sub 2}O{sub 3} hollow nanostructures with diameters of approximately 200 nm and shell thickness of about 20 nm. The X-ray diffraction analysis revealed that the carbon@Ga(OH)CO{sub 3} core–shell nanostructures were in amorphous phase before calcination. After calcination, the amorphous core–shell structures yielded highly crystalline β-Ga{sub 2}O{sub 3} hollow nanostructures with spherical shape. The presence of the Ga(OH)CO{sub 3} in the shell components is confirmed by the Fourier transform infrared spectrum. The Eu{sup 3+} doped β-Ga{sub 2}O{sub 3} hollow nanostructures showed strong red emission corresponding to the {sup 5}D{sub 4} → {sup 7}F{sub J} transition. - Highlights: • The hollow nanostructures were synthesized by hydrothermal and calcination processes. • The shells consist of Ga(OH)CO{sub 3} and are amorphous phase with thickness 20 nm. • The highly crystalline β-Ga{sub 2}O{sub 3} hollow structures were formed with diameters of 200 nm. • The β-Ga{sub 2}O{sub 3}:Eu{sup 3+} (3 mol%) hollow nanostructures at 900 °C show the highest red emission.

  17. Production and cross-sectional characterization of aligned co-electrospun hollow microfibrous bulk assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Feng-Lei [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); The School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester (United Kingdom); Parker, Geoff J.M., E-mail: geoff.parker@manchester.ac.uk [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester (United Kingdom); Eichhorn, Stephen J. [College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Hubbard Cristinacce, Penny L. [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); School of Psychological Sciences, University of Manchester, Manchester M13 9PT (United Kingdom)

    2015-11-15

    The development of co-electrospun (co-ES) hollow microfibrous assemblies of an appreciable thickness is critical for many practical applications, including filtration membranes and tissue-mimicking scaffolds. In this study, thick uniaxially aligned hollow microfibrous assemblies forming fiber bundles and strips were prepared by co-ES of polycaprolactone (PCL) and polyethylene oxide (PEO) as shell and core materials, respectively. Hollow microfiber bundles were deposited on a fixed rotating disc, which resulted in non-controllable cross-sectional shapes on a macroscopic scale. In comparison, fiber strips were produced with tuneable thickness and width by additionally employing an x–y translation stage in co-ES. Scanning electron microscopy (SEM) images of cross-sections of fiber assemblies were analyzed to investigate the effects of production time (from 0.5 h to 12 h), core flow rate (from 0.8 mL/h to 2.0 mL/h) and/or translation speed (from 0.2 mm/s to 5 mm/s) on the pores and porosity. We observed significant changes in pore size and shape with core flow rate but the influence of production time varied; five strips produced under the same conditions had reasonably good size and porosity reproducibility; pore sizes didn't vary significantly from strip bottom to surface, although the porosity gradually decreased and then returned to the initial level. - Highlights: • Hollow microfibrous assemblies based on co-electrospinning are demonstrated. • The thickness and width of co-electrospun strips were controllable. • Cross-sections of fibres had non-normally distributed pore sizes and shapes. • Cross-sections were significantly influenced by production time and flow rate. • Co-electrospun strips had reasonably good reproducible cross-sections.

  18. Nanoporous CuS nano-hollow spheres as advanced material for high-performance supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, Hamid [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Moosavifard, Seyyed Ebrahim, E-mail: info_seyyed@yahoo.com [Young Researchers and Elite Club, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Elyasi, Saeed [Department of Chemical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Shahraki, Mohammad [Department of Chemistry, University of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of)

    2017-02-01

    Highlights: • Nanoporous CuS nano-hollow spheres were synthesized by a facile method. • Nano-hollow spheres have a large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). • Such unique structures exhibit excellent electrochemical properties for high-performance SCs. - Abstract: Due to unique advantages, the development of high-performance supercapacitors has stimulated a great deal of scientific research over the past decade. The electrochemical performance of a supercapacitor is strongly affected by the surface and structural properties of its electrode materials. Herein, we report a facile synthesis of high-performance supercapacitor electrode material based on CuS nano-hollow spheres with nanoporous structures, large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). This interesting electrode structure plays a key role in providing more active sites for electrochemical reactions, short ion and electron diffusion pathways and facilitated ion transport. The CuS nano-hollow spheres electrode exhibits excellent electrochemical performance including a maximum specific capacitance of 948 F g{sup −1} at 1 A g{sup −1}, significant rate capability of 46% capacitance retention at a high current density of 50 A g{sup −1}, and outstanding long-term cycling stability at various current densities. This work not only demonstrates the promising potential of the CuS-NHS electrodes for application in high-performance supercapacitors, but also sheds a new light on the metal sulfides design philosophy.

  19. Trends of contact lens prescribing in Jordan.

    Science.gov (United States)

    Haddad, Mera F; Bakkar, May; Gammoh, Yazan; Morgan, Philip

    2016-10-01

    To evaluate contact lens prescribing trends among optometrists in Jordan. Optometrists from 173 practices in Jordan were surveyed about prescribing contact lenses in their practice. Practitioners were required to record information for the last 10 patients that visited their practice. Demographic data such as age and gender was obtained for each patient. In addition, data relating to lens type, lens design, replacement methods and the care regime advised to each patient were recorded. Practitioners were required to provide information relating to their education and years of experience. The influence of education and experience with respect to lens prescribing trends was explored using linear regression models for the proportions of lens types fitted for patients. A total of 1730 contact lens fits were analyzed. The mean (±SD) age of lens wearers was 26.6 (±7.9) years, of whom 65% were female. Conventional hydrogel lenses were the most prescribed lenses, accounting for 60.3% of the fits, followed by silicone hydrogel lenses (31.3%), and rigid lenses (8.4%). In terms of lens design, spherical lenses appeared to be most commonly prescribed on monthly basis. Daily disposable lenses were second most prescribed lens modality, accounting for 20.4% of the study sample. Multi-purpose solution (MPS) was the preferred care regimen, with a prevalence of 88.1% reported in the study sample, compared to hydrogen peroxide (1-step and 2-step), which represented only 2.8% of the patients in this study. A relationship was established between the two educational groups for rigid lens prescribing (F=17.4, p<0.0001), while the experience of the optometrist was not a significant factor (F=0.4, p=0.54). This work has provides an up-to-date analysis of contact lens prescribing trends among optometrists in Jordan. Contact lens prescribing in terms of lens type, lens design, modality of wear and care regimen agree with global market trends with small variations. This report will help

  20. The selection of small forest hollows for pollen analysis in boreal and temperate forest regions

    DEFF Research Database (Denmark)

    Overballe-Petersen, Mette V; Bradshaw, Richard H.W.

    2011-01-01

    Small forest hollows represent a specialised site type for pollen analysis, since they mainly record the vegetation within an approximate radius of 20-100 m from the hollow. We discuss how to choose the most appropriate small forest hollow for pollen analysis. Hollow size, site topography, location...

  1. Induction spectrometry using an ultrafast hollow-cored toroidal-coil (HTC) detector

    Science.gov (United States)

    Arbelo, Yunieski; Bleiner, Davide

    2017-02-01

    Ultrafast photoelectron and photoion spectroscopy (as well as their combination known as "coincidence spectroscopy") utilizes detectors based on different electron multipliers such as microchannel plates or single-channel electron multipliers. These detectors have a few important limitations such as fast-signal distortion (low pass operation), mutually exclusive positive or negative mode, dead time, and requirement of trigger. A high-pass induction detector, based on a hollow-cored toroidal coil, was developed that overcomes the above-mentioned limitations. The frequency-dispersive response and linearity of different configurations were analyzed. It is shown that the response is enhanced for ultrafast electron signals, dependent on construction parameters, thus offering response flexibility by design. Kinetic energy distributions of pseudospark-induced electron pulses are characterized in order to validate the capabilities in real applications.

  2. Demonstration of the hollow channel plasma wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Gessner, Spencer J.

    2016-09-17

    A plasma wakefield accelerator is a device that converts the energy of a relativistic particle beam into a large-amplitude wave in a plasma. The plasma wave, or wakefield, supports an enormous electricfield that is used to accelerate a trailing particle beam. The plasma wakefield accelerator can therefore be used as a transformer, transferring energy from a high-charge, low-energy particle beam into a high-energy, low-charge particle beam. This technique may lead to a new generation of ultra-compact, high-energy particle accelerators. The past decade has seen enormous progress in the field of plasma wakefield acceleration with experimental demonstrations of the acceleration of electron beams by several gigaelectron-volts. The acceleration of positron beams in plasma is more challenging, but also necessary for the creation of a high-energy electron-positron collider. Part of the challenge is that the plasma responds asymmetrically to electrons and positrons, leading to increased disruption of the positron beam. One solution to this problem, first proposed over twenty years ago, is to use a hollow channel plasma which symmetrizes the response of the plasma to beams of positive and negative charge, making it possible to accelerate positrons in plasma without disruption. In this thesis, we describe the theory relevant to our experiment and derive new results when needed. We discuss the development and implementation of special optical devices used to create long plasma channels. We demonstrate for the first time the generation of meter-scale plasma channels and the acceleration of positron beams therein.

  3. MOF-Templated Fabrication of Hollow Co4N@N-Doped Carbon Porous Nanocages with Superior Catalytic Activity.

    Science.gov (United States)

    Sheng, Jianping; Wang, Liqiang; Deng, Liu; Zhang, Min; He, Haichuan; Zeng, Ke; Tang, Feiying; Liu, You-Nian

    2018-02-13

    Metallic Co 4 N catalysts have been considered as one of the most promising non-noble materials for heterogeneous catalysis because of their high electrical conductivity, great magnetic property, and high intrinsic activity. However, the metastable properties seriously limit their applications for heterogeneous water phase catalysis. In this work, a novel Co-metal-organic framework (MOF)-derived hollow porous nanocages (PNCs) composed of metallic Co 4 N and N-doped carbon (NC) were synthesized for the first time. This hollow three-dimensional (3D) PNC catalyst was synthesized by taking advantage of Co-MOF as a precursor for fabricating 3D hollow Co 3 O 4 @C PNCs, along with the NH 3 treatment of Co-oxide frames to promote the in situ conversion of Co-MOF to Co 4 N@NC PNCs, benefiting from the high intrinsic activity and electron conductivity of the metallic Co 4 N phase and the good permeability of the hollow porous nanostructure as well as the efficient doping of N into the carbon layer. Besides, the covalent bridge between the active Co 4 N surface and PNC shells also provides facile pathways for electron and mass transport. The obtained Co 4 N@NC PNCs exhibit excellent catalytic activity and stability for 4-nitrophenol reduction in terms of low activation energy (E a = 23.53 kJ mol -1 ), high turnover frequency (52.01 × 10 20 molecule g -1 min -1 ), and high apparent rate constant (k app = 2.106 min -1 ). Furthermore, its magnetic property and stable configuration account for the excellent recyclability of the catalyst. It is hoped that our finding could pave the way for the construction of other hollow transition metal-based nitride@NC PNC catalysts for wide applications.

  4. Formation map of air-liquid hollow profile under microgravity

    Energy Technology Data Exchange (ETDEWEB)

    Ohira, Y.; Kuga, Y.; Ando, K. [Muroran Institute of Technology, Hokkaido (Japan). Dept. of Applied Chemistry; Idogawa, K.; Fukuda, T. [Hokkaido National Industrial Research Institute, Hokkaido (Japan)

    2000-04-01

    From the viewpoint of oxygen recovery and supply in a space station, the formation of an air-liquid hollow profile which has a suitable interface shape to cultivate microalgae under microgravity conditions is experimentally investigated. The air-liquid interface profiles in a rotating vessel were observed and recorded. The effects of the modified Weber number and modified Reynolds number on formation of the air-liquid hollow profile were experimentally investigated. We developed a basis for judging conditions forming the air-liquid hollow profile from the video images. When the volume ratio of the liquid/vessel is 0.60 and the modified Weber number is greater than 2.2, it is found that the air-liquid hollow profile forms and is independent of the modified Reynolds number. From the experimental results using liquids with different surface tension, the validity of using the modified Weber number is confirmed as a dimensionless number for judging the formation of the air-liquid hollow profile. It is experimentally found that the formation conditions for the air-liquid hollow profile under microgravity can be determined by the modified Weber number and the volume ratio of the liquid/vessel. In a map of the volume ratio of the liquid/vessel vs. the modified Weber number, the discrimination of the formation of the air-liquid hollow profile is performed by a line experimentally obtained in this study. (author)

  5. Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO₄/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries.

    Science.gov (United States)

    Liu, Yang; Zhang, Jieyu; Li, Ying; Hu, Yemin; Li, Wenxian; Zhu, Mingyuan; Hu, Pengfei; Chou, Shulei; Wang, Guoxiu

    2017-11-03

    To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO₄/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide (CTAB) as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO₄/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO₄/C composite exhibits superior discharge capacity (163 mAh g-1 at 0.1 C), good high-rate discharge capacity (118 mAh g-1 at 10 C), and fine cycling stability (99.2% after 200 cycles at 0.1 C). The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure.

  6. Scalable synthesis of Na3V2(PO4)(3)/C porous hollow spheres as a cathode for Na-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Mao, JF; Luo, C; Gao, T; Fan, XL; Wang, CS

    2015-01-01

    Na3V2(PO4)(3) (NVP) has been considered as a very promising cathode material for sodium-ion batteries (SIBs) due to its typical NASICON structure, which provides an open and three dimensional (3D) framework for Na+ migration. However, the low electronic conductivity of NVP limits its rate capability and cycling ability. In this study, carbon coated hollow structured NVP/C composites are synthesized via a template-free and scalable ultrasonic spray pyrolysis process, where the carbon coated NVP particles are uniformly decorated on the inner and outer surfaces of the porous hollow carbon spheres. When evaluated as a cathode material for SIBs, the unique NVP/C porous hollow sphere cathode delivers an initial discharge capacity of 99.2 mA h g(-1) and retains 89.3 mA h g(-1) after 300 charge/discharge cycles with a very low degradation rate of 0.035% per cycle. For comparison, the NVP/C composite, prepared by the traditional sol-gel method, delivers a lower initial discharge capacity of 97.4 mA h g(-1) and decreases significantly to 71.5 mA h g(-1) after 300 cycles. The superior electrochemical performance of NVP/C porous hollow spheres is attributed to their unique porous, hollow and spherical structures, as well as the carbon-coating layer, which provides a high contact area between electrode/electrolyte, high electronic conductivity, and high mechanical strength.

  7. Near Band Edge Emission by Free Exciton Decay and Intrinsic Ferromagnetic Ordering of Cu-Doped SnO2 Hollow Nanofibers.

    Science.gov (United States)

    Mohanapriya, P; Jaya, N Victor

    2015-03-01

    High quality nanocrystalline pristine and Cu-doped SnO2 hollow nanofibers were successfully prepared through simple and effective electrospinning technique. Nanofibers calcined at 600 °C for 3 h were characterized with different analytical techniques such as X-ray diffraction (XRD), Transmission electron Microscope (TEM) and Vibrating sample magnetometer (VSM). Observed TEM images and XRD patterns were corroborate to the formation of tetragonal crystalline SnO2 hollow nanofibers with rutile phase. Excellent optical behaviour was observed for Cu-doped SnO2. Highly intense near band edge emission at 3.58 eV for Cu-doped SnO2 evidences the free exciton decay process in the hollow nanofibers. For the first time we have reported here the near band edge PL emission in Cu-doped SnO2 tubular hollow nanostructure. This study substantiates that material potential for UV-lasing application. In addition to the above, magnetic measurement ascribes that Cu-doped SnO2 exhibit the intrinsic room temperature ferromagnetism within the low field strength. The occurrence of ferromagnetism in Cu-doped SnO2 is directly related to the p-d ferromagnetic exchange coupling between the local magnetic moment of Cu2+ and the polarized valence electrons of surrounding oxygen. Over all this study provides the primary information about tunable multifunctionality of SnO2 hollow nanostructures by adding the non-magnetic Cu ions.

  8. Heterogeneous photo-Fenton processes using graphite carbon coating hollow CuFe2O4 spheres for the degradation of methylene blue

    Science.gov (United States)

    Guo, Xiaojun; Wang, Kebai; Li, Dai; Qin, Jiabin

    2017-10-01

    The novel graphite carbon coating hollow CuFe2O4 spheres were fabricated through solvothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectra, etc. The catalytic performance of the graphite carbon coating hollow CuFe2O4 spheres was evaluated in photo-Fenton-like degradation of methylene blue (MB) using H2O2 as a green oxidant under light irradiation (λ > 400 nm). The results demonstrated that the hollow CuFe2O4 spheres with graphite carbon coating exhibited superior catalytic activity. In the preparation process of catalyst, the addition of glucose was very important to its catalytic performance. Photoresponse analysis of the typical samples proved that CuFe2O4@graphite carbon core-shell hollow spheres possessed excellent photocurrent response and lower electrochemical impedance. In addition, a possible mechanism for photocatalytic degradation of MB had been presumed. Moreover, after five regeneration cycles, the graphite carbon coating hollow CuFe2O4 spheres still exhibited better properties.

  9. Evolution of a pre and post lens tear film with a contact lens

    Science.gov (United States)

    Gerhart, Matthew; Anderson, Daniel

    2012-11-01

    The work is the development, implementation, and analysis of a two-dimensional tear film model including a porous contact lens. The geometry of the problem is: a pre-lens layer that is a thin tear film between the outside air and contact lens, a contact lens that is a rigid but movable porous substrate, and a post-lens layer that is a thin film layer between the contact lens and the cornea. We are looking at short and long term behavior of the evolution of the thin film in the pre-lens layer coupled with the porous layer and the thin squeeze film in the post-lens layer. We model the different behaviors that arise as the Darcy number, evaporation effects, and boundary flux conditions change.

  10. Contact lens fitting after photorefractive keratectomy.

    OpenAIRE

    Astin, C. L.; Gartry, D S; McG Steele, A. D.

    1996-01-01

    AIMS/BACKGROUND: This study evaluated contact lens fitting and the longer term response of the photorefractive keratectomy (PRK) cornea to lens wear. In PRK for myopia problems such as regression, anterior stromal haze, irregular astigmatism, halo aberration, and anisometropia have been reported. Certain patients therefore require contact lens correction to obtain best corrected visual acuity (BCVA). METHOD: From an original cohort of 80 patients, 15 were dissatisfied with their visual outcom...

  11. Hard contact lens-induced metabolic changes in rabbit corneas.

    Science.gov (United States)

    Tsubota, K; Kenyon, K R; Cheng, H M

    1989-11-01

    The biochemistry of contact lens-cornea interaction is not well understood, although previous studies have suggested that corneal metabolic changes may be the underlying factor in morphological alterations. Using a rabbit model, this interaction has been examined with 31P nuclear magnetic resonance (NMR) spectroscopy, which detects signals principally from the epithelium. The examination was supplemented with electron microscopy and histochemistry. Polymethylmethacrylate lenses caused reversible changes, including activation of anaerobic glycolysis and disturbance of membrane metabolite levels. These changes were far more severe than those occurring during prolonged eye closure. There appears to be an association between cellular deterioration and loss of membrane metabolites. On the other hand, oxygen-permeable silicone lenses allowed maintenance of nearly normal metabolic patterns. These results show multifaceted corneal response to hard contact lens wear.

  12. The Hollow Spheres of the Orgueil Meteorite: A Re-Examination

    Science.gov (United States)

    Hoover, Richard B.; Jerman, Gregory; Rossignold-Strick, Maritine

    2005-01-01

    In 1971, Rossignol-Strick and Barghoorn provided images and a description of a number of spherical hollow microstructures showing well-defined walls in acid macerated extract of the Orgueil CI carbonaceous meteorite. Other forms such as membranes and spiral shaped structures were also reported. The carbon-rich (kerogen) hollow spheres were found to be in a narrowly constrained distribution of sizes (mainly 7 to 10 microns in diameter). Electron microprobe analysis revealed that these spheres contained Carbon, possibly P, N, and K. It was established that these forms could not be attributed to pollen or other recent terrestrial contaminants. It was concluded that they most probably represented organic coatings on globules of glass, olivine or magnetite in the meteorite. However, recent studies of the Orgueil meteorite have been carried out at the NASA/Marshall Space Flight Center with the S-4000 Hitachi Field Emission Scanning Electron Microscope (FESEM). These investigations have revealed the presence of numerous carbon encrusted spherical magnetite platelets and spherical and ovoidal bodies of elemental iron in-situ in freshly fractured interior surfaces of the meteorite. Their size range is also very narrowly constrained (typically approximately 6 to 12 microns) in diameter. High resolution images reveal that these bodies are also encrusted with a thin carbonaceous sheath and are surrounded by short nanofibrils that are shown to be composed of high purity iron by EDAX elemental analysis. We present Secondary and Backscatter Electron FESEM images and associated EDAX elemental analyses and 2D X-ray maps of these forms as we re-examine the hollow spheres of Orgueil and attempt to determine if they are representatives of the same population of indigenous microstructures.

  13. Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder

    Directory of Open Access Journals (Sweden)

    E. S. Nehru

    2012-01-01

    Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.

  14. Hollow fiber membranes and methods for forming same

    Science.gov (United States)

    Bhandari, Dhaval Ajit; McCloskey, Patrick Joseph; Howson, Paul Edward; Narang, Kristi Jean; Koros, William

    2016-03-22

    The invention provides improved hollow fiber membranes having at least two layers, and methods for forming the same. The methods include co-extruding a first composition, a second composition, and a third composition to form a dual layer hollow fiber membrane. The first composition includes a glassy polymer; the second composition includes a polysiloxane; and the third composition includes a bore fluid. The dual layer hollow fiber membranes include a first layer and a second layer, the first layer being a porous layer which includes the glassy polymer of the first composition, and the second layer being a polysiloxane layer which includes the polysiloxane of the second composition.

  15. Hierarchical FeTiO3-TiO2 hollow spheres for efficient simulated sunlight-driven water oxidation

    Science.gov (United States)

    Han, Taoran; Chen, Yajie; Tian, Guohui; Wang, Jian-Qiang; Ren, Zhiyu; Zhou, Wei; Fu, Honggang

    2015-09-01

    Oxygen generation is the key step for the photocatalytic overall water splitting and considered to be kinetically more challenging than hydrogen generation. Here, an effective water oxidation catalyst of hierarchical FeTiO3-TiO2 hollow spheres are prepared via a two-step sequential solvothermal processes and followed by thermal treatment. The existence of an effective heterointerface and built-in electric field in the surface space charge region in FeTiO3-TiO2 hollow spheres plays a positive role in promoting the separation of photoinduced electron-hole pairs. Surface photovoltage, transient-state photovoltage, fluorescence and electrochemical characterization are used to investigate the transfer process of photoinduced charge carriers. The photogenerated charge carriers in the hierarchical FeTiO3-TiO2 hollow spheres with a proper molar ratio display much higher separation efficiency and longer lifetime than those in the FeTiO3 alone. Moreover, it is suggested that the hierarchical porous hollow structure can contribute to the enhancement of light utilization, surface active sites and material transportation through the framework walls. This specific synergy significantly contributes to the remarkable improvement of the photocatalytic water oxidation activity of the hierarchical FeTiO3-TiO2 hollow spheres under simulated sunlight (AM1.5).Oxygen generation is the key step for the photocatalytic overall water splitting and considered to be kinetically more challenging than hydrogen generation. Here, an effective water oxidation catalyst of hierarchical FeTiO3-TiO2 hollow spheres are prepared via a two-step sequential solvothermal processes and followed by thermal treatment. The existence of an effective heterointerface and built-in electric field in the surface space charge region in FeTiO3-TiO2 hollow spheres plays a positive role in promoting the separation of photoinduced electron-hole pairs. Surface photovoltage, transient-state photovoltage, fluorescence and

  16. Fabrication and formation mechanism of poly (L-lactic acid ultrafine multi-porous hollow fiber by electrospinning

    Directory of Open Access Journals (Sweden)

    Q. Z. Yu

    2013-01-01

    Full Text Available Poly(L-lactic acid (PLLA ultrafine multi-porous hollow fibers are fabricated by electrospinning with methylene dichloride as solvent. The Kirkendall effect has been widely applied for the fabrication of hollow structure in metals and inorganic materials. In this study, a conceptual extension is proposed for the formation mechanism: the development of porous hollow fiber undergoes three stages. The initial stage is the generation of small voids or pits on the surface of the fiber via surface diffusion and phase separation; the second stage is the formation of multi-pores penetrating the core of the fiber through the interaction of Kirkendall effect, surface diffusion and phase separation; the third stage is dominated by surface diffusion of the core material along the pore surface. To explore the formation conditions, the factors including ambient temperature, relativity humidity (R. H., molecular weight and fiber diameter are studied. The longitudinal and cross sectional morphologies of these fibers are examined by scanning electron micrograph (SEM. The results show that the prerequisite for the formation of uniform porous hollow PLLA fibers include moderate ambient temperature (10~20°C and appropriate molecular weight for the PLLA, as well as the diameter of the fiber in the range of several micrometers to about 100 nanometers.

  17. Permeability of Hollow Microspherical Membranes to Helium

    Science.gov (United States)

    Zinoviev, V. N.; Kazanin, I. V.; Pak, A. Yu.; Vereshchagin, A. S.; Lebiga, V. A.; Fomin, V. M.

    2016-01-01

    This work is devoted to the study of the sorption characteristics of various hollow microspherical membranes to reveal particles most suitable for application in the membrane-sorption technologies of helium extraction from a natural gas. The permeability of the investigated sorbents to helium and their impermeability to air and methane are shown experimentally. The sorption-desorption dependences of the studied sorbents have been obtained, from which the parameters of their specific permeability to helium are calculated. It has been established that the physicochemical modification of the original particles exerts a great influence on the coefficient of the permeability of a sorbent to helium. Specially treated cenospheres have displayed high efficiency as membranes for selective extraction of helium.

  18. Hollow micro string based calorimeter device

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a micron-scale calorimeter and a calorimetry method utilizing the micron-scale calorimeter. In accordance with the invention, there is provided a micron-scale calorimeter comprising a micro-channel string, being restrained at at least two longitudinally distanced...... positions so as to form a free released double clamped string in-between said two longitudinally distanced positions said micro-channel string comprising a microfluidic channel having a closed cross section and extending in the longitudinal direction of the hollow string, acoustical means adapted...... to oscillate the string at different frequencies by emitting sound waves towards the string, optical means adapted to detect oscillating frequencies of the string, and controlling means controlling the strength and frequency of the sound wave emitted by the acoustical means and receiving a signal from...

  19. Two-piece hollow bulb obturator

    Directory of Open Access Journals (Sweden)

    Subramaniam Elangovan

    2011-01-01

    Full Text Available There are various types of obturator fabrication achievable by prosthodontist. Maxillectomy, which is a term used by head and neck surgeons and prosthodontists to describe the partial or total removal of the maxilla in patients suffering from benign or malignant neoplasms is a defect for which to provide an effective obturator is a difficult task for the maxillofacial prosthodontist. Multidisciplinary treatment planning is essential to achieve adequate retention and function for the prosthesis. Speech is often unintelligible as a result of the marked defects in articulation and nasal resonance. This paper describes how to achieve the goal for esthetics and phonetics and also describes the fabrication of a hollow obturator by two piece method, which is simple and maybe used as definitive obturator for maximum comfort of the patient.

  20. Synthesis and characterization of sub-10 nm Platinum Hollow Spheres as electrocatalyst of direct methanol fuel cell.

    Science.gov (United States)

    Li, Jun; Liang, Ying; Xu, Qing-Chi; Fu, Xian-Zhu; Xu, Jeff Qiang; Lin, Jing-Dong; Liao, Dai-Wei

    2006-04-01

    Platinum Hollow Spheres (PHSs) with diameters less than 10 nm were successfully synthesized by using Co as a sacrificial template and H2PtCl6 as an oxidizing agent at 95 degrees C. The formation of PHSs at this temperature was not affected by citrate reduction and mainly depended on the pH. The results of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the platinum hollow sphere was mainly constructed by fcc (face cubic center) platinum with tiny crystallites on the shell. The performance of PHSs for methanol electro-oxidation was evaluated and compared with commercial E-TEK platinum black. Electrochemical measurement by cyclic voltammetry (CV) demonstrated that the electrochemical surface area of PHSs was about twice higher than E-TEK platinum black. Therefore, the synthesized PHSs had higher electrocatalytic activity for methanol electro-oxidation.

  1. Changes in lens stiffness due to capsular opacification in accommodative lens refilling

    NARCIS (Netherlands)

    Nibourg, Lisanne M.; Sharma, Prashant K.; van Kooten, Theo G.; Koopmans, Steven A.

    Accommodation may be restored to presbyopic lenses by refilling the lens capsular bag with a soft polymer. After this accommodative lens refilling prevention of capsular opacification is a requirement, since capsular opacification leads to a decreased clarity of the refilled lens. It has been

  2. Aquaporin 0 plays a pivotal role in refractive index gradient development in mammalian eye lens to prevent spherical aberration

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, S. Sindhu [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); Varadaraj, Kulandaiappan, E-mail: kulandaiappan.varadaraj@stonybrook.edu [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, New York, NY (United States)

    2014-10-03

    . Transmission and scanning electron micrographs of lenses of both mouse models showed increased extracellular space between fiber cells. Water content determination study showed increase in water in the lenses of these mouse models. In summary, lens transparency, CTCA and compact packing of fiber cells were affected due to the loss of 50% AQP0 leading to larger extracellular space, more water content and SA, possibly due to alteration in RING. To our knowledge, this is the first report identifying the role of AQP0 in RING development to ward off lens SA during focusing.

  3. Flat lens for seismic waves

    CERN Document Server

    Brule, Stephane; Guenneau, Sebastien

    2016-01-01

    A prerequisite for achieving seismic invisibility is to demonstrate the ability of civil engineers to control seismic waves with artificially structured soils. We carry out large-scale field tests with a structured soil made of a grid consisting of cylindrical and vertical holes in the ground and a low frequency artificial source (< 10 Hz). This allows the identification of a distribution of energy inside the grid, which can be interpreted as the consequence of an effective negative refraction index. Such a flat lens reminiscent of what Veselago and Pendry envisioned for light opens avenues in seismic metamaterials to counteract the most devastating components of seismic signals.

  4. Non-self-sustained discharge with hollow anode for plasma-based surface treatment

    Directory of Open Access Journals (Sweden)

    Misiruk Ivan O.

    2016-06-01

    Full Text Available The paper discusses plasma methods for surface modification using the non-self-sustained glow discharge with a hollow anode. This discharge is characterised by low voltage and high values of electron and ion currents. It can be easily excited in vacuum-arc installations that are widely used for coatings deposition. It is shown that such type of discharge may be effectively used for ion pumping, film deposition, ion etching, diffusion saturation of metallic materials, fusion and brazing of metals, and for combined application of above mentioned technologies in a single vacuum cycle.

  5. The Effect of Scattering Layer on the Performance of Dye-Sensitized Solar Cells Using TiO2 Hollow Spheres/TiO2 Nanoparticles Films as Photoanodes.

    Science.gov (United States)

    Park, Su Kyung; Suh, Soong-Hyuck; Lee, Min Woo; Yun, Tae Kwan; Bae, Jae Young

    2015-10-01

    TiO2 hollow spheres were successfully synthesized using poly styrene as the template. Dye-sensitized solar cells are fabricated based on double-layered composite films of TiO2 nanoparticles and TiO2 hollow spheres. The photoelectric conversion performances of Dye-sensitized solar cells based on TiO2 nanoparticles/TiO2 nanoparticles, TiO2 nanoparticles/TiO2 hollow spheres and TiO2 hollow spheres/TiO2 hollow spheres double-layered films are investigated, and their photoelectric conversion efficiencies were determined to 4.52, 7.10 and 5.48%, respectively. Dye-sensitized solar cells based on double layered composite films of TiO2 nanoparticles and TiO2 hollow spheres exhibit the highest photo-electric conversion efficiency mainly due to the combined effect of two factors, the high light scattering of over-layer hollow spheres that enhance harvesting light of the Dye-sensitized solar cells and the under-layer TiO2 nanoparticle layer that ensures good electronic contact between TiO2 film and FTO conducting glass. The double layered composite TiO2 film electrodes are a promising development in enhancing the performance of dye-sensitized solar cells.

  6. High strength and low weight hollow carbon fibres

    Science.gov (United States)

    Köhler, T.; Brüll, R.; Pursche, F.; Langgartner, J.; Seide, G.; Gries, T.

    2017-10-01

    Carbon fibres have strengths of 2.5 to 5 GPa in the fibre direction and an elastic modulus of 200 to 500 GPa. Carbon fibres have equal mechanical properties as steel but 20% of the weight. But the material is more expensive than steel. Therefore, they are only used in industry sectors where the benefits legitimate the high costs. The use of hollow rather than solid fibres allows an even lower weight of the components. At the same time, similar mechanical properties are achieved by the circular cross section. Carbon fibres are obtained from polyacrylonitrile fibers (PAN). These can be produced as hollow fibres. As a first step stabilization and carbonization of hollow PAN precursors is investigated to produce hollow carbon fibres.

  7. Hollow Au–Ag Alloy Nanorices and Their Optical Properties

    Directory of Open Access Journals (Sweden)

    Keke Yu

    2017-09-01

    Full Text Available Hollow noble metal nanoparticles have excellent performance not only in surface catalysis but also in optics. In this work, the hollow Au–Ag alloy nanorices are fabricated by the galvanic replacement reaction. The dark-field spectrum points out that there is a big difference in the optical properties between the pure Ag nanorices and the hollow alloy nanorices that exhibit highly tunable localized surface plasmon resonances (LSPR and that possess larger radiative damping, which is also indicated by the finite element method. Furthermore, the surface enhanced Raman scattering (SERS and oxidation test indicate that hollow Au–Ag alloy nanorices show good anti-oxidation and have broad application prospects in surface-plasmon-related fields.

  8. Fabricating customized hydrogel contact lens

    Science.gov (United States)

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-10-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

  9. Laser-plasma-based linear collider using hollow plasma channels

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, C.B., E-mail: CBSchroeder@lbl.gov; Benedetti, C.; Esarey, E.; Leemans, W.P.

    2016-09-01

    A linear electron–positron collider based on laser-plasma accelerators using hollow plasma channels is considered. Laser propagation and energy depletion in the hollow channel is discussed, as well as the overall efficiency of the laser-plasma accelerator. Example parameters are presented for a 1-TeV and 3-TeV center-of-mass collider based on laser-plasma accelerators.

  10. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Energy Technology Data Exchange (ETDEWEB)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  11. Flat Bunches with a Hollow Distribution for Space Charge Mitigation

    CERN Document Server

    Oeftiger, Adrian; Findlay, Alan James; Hancock, Steven; Rumolo, Giovanni

    2016-01-01

    Longitudinally hollow bunches provide one means to mitigate the impact of transverse space charge. The hollow distributions are created via dipolar parametric excitation during acceleration in CERN's Proton Synchrotron Booster. We present simulation work and beam measurements. Particular emphasis is given to the alleviation of space charge effects on the long injection plateau of the downstream Proton Synchrotron machine, which is the main goal of this study.

  12. Highly efficient fluorescence sensing with hollow core photonic crystal fibers

    DEFF Research Database (Denmark)

    Smolka, Stephan; Barth, Michael; Benson, Oliver

    2008-01-01

    We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes.......We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes....

  13. Liquid Temperature Measurements Using Two Different Tunable Hollow Prisms.

    Science.gov (United States)

    Calixto, Sergio; Rosete-Aguilar, Martha; Torres-Gomez, Ismael

    2017-01-29

    This paper describes the design, fabrication, and testing of two hollow prisms. One is a prism with a grating glued to its hypotenuse. This ensemble, prism + grating, is called a grism. It can be applied as an on-axis tunable spectrometer. The other hollow prism is a constant deviation one called a Pellin-Broca. It can be used as a tunable dispersive element in a spectrometer with no moving parts. The application of prisms as temperature sensors is shown.

  14. 3D hollow nanostructures as building blocks for multifunctional plasmonics

    KAUST Repository

    De Angelis, Francesco De

    2013-08-14

    We present an advanced and robust technology to realize 3D hollow plasmonic nanostructures which are tunable in size, shape, and layout. The presented architectures offer new and unconventional properties such as the realization of 3D plasmonic hollow nanocavities with high electric field confinement and enhancement, finely structured extinction profiles, and broad band optical absorption. The 3D nature of the devices can overcome intrinsic difficulties related to conventional architectures in a wide range of multidisciplinary applications. © 2013 American Chemical Society.

  15. PREVALENCE OF LENS OPACITY AT QUEEN ELIZABETH ...

    African Journals Online (AJOL)

    hi-tech

    of the optical homogeneity of the lens and this definition includes lens vacuoles, water clefts, dense areas, ... health needs, and to determine the risk factors that influence the social and economic burden associated with the .... hazards of jobs mainly reserved for individual sexes. On the other hand, some studies have shown ...

  16. [Contact lens in children: epidemiological aspects].

    Science.gov (United States)

    Salame, André Luiz Alves; Simon, Eduardo José Maidana; Leal, Fernando; Lipener, César; Brocchetto, Daniela

    2008-01-01

    To describe the epidemiology of children submitted to contact lens fit. Retrospective study of 73 children that had been submitted to contact lens fit at the "Universidade Federal de São Paulo". This study analyzed sex distribution, age, diagnosis, indications and contact lens fitted at first examination. 34 children (46.6%) were male and 39 (53.4%) female, aged between 2 and 12 years with mean of 10.2 and standard deviation of 2.42. The most common diagnosis was aphakia, in 16 (21.9%) cases. Keratoconus was present in 14 (19.1%), leucoma in 11 (15%), anisometropia in 10 (13.7%), refractive errors in 9 (12.3%), irregular astigmatism in 7 (9.5%), ectopia lentis in 4 (5.4%), high myopia in one case (1.3%) and one child (1.3%) had no ocular pathology, just wishing to change eye color. 52 (71.2%) had medical indication, 9 (12.3%) had optical indication and 12 (16.4%) had cosmetic indication. Contact lenses were fitted in 103 eyes, the most tested lens was rigid gas permeable in 43 (41.7%), soft lens in 41 (39.8%) and cosmetic soft lens in 11 (10.6%). Aphakia was the most common diagnosis among children in use of contact lens. The incidence of medical indication was higher than the others and the most tested lens was the rigid gas permeable one.

  17. Modified suturing contact lens for penetrating keratoplasty.

    Science.gov (United States)

    Kramer, S G; Stewart, H L

    1978-11-01

    The authors have previously described a suturing contact lens that protects the corneal endothelium by aiding in the maintenance of the anterior chamber during penetrating keratoplasty. This report describes structural modifications of the suturing contact lens, which improve its stability and effectiveness. An additional configuration for use in corneal lacerations is presented.

  18. Studies on hollow spherical aluminum silicate cluster. Synthesis of environment friendly materials; Chuku kyujo aluminium keisan`en cluster ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, F.; Maeda, M.; Suzuki, M.; Watamura, S. [National Industrial Research Institute of Nagoya,Nagoya (Japan)

    1999-01-25

    Synthesis of microfine particles of nanometer size, their surface adulteration and control of microstructure take an important position in different areas, such as electronics, chemical, machine and metal industries. However, reports on the established methods for synthesizing hollow spherical particles of nanometer size, which may be applied to micro capsules, cannot be found except for fullerene composed of carbon. This paper introduces a new method for synthesizing hollow spherical amorphous aluminum silicate cluster called allophane as an earth environmental material, and the derived properties of allophane. (translated by NEDO)

  19. Field emission from entangled carbon nanotubes coated on/in a hollow metallic tube

    CERN Document Server

    Tokura, Y; Ohigashi, N; Akita, S; Nakayama, Y; Imasaki, K; Mima, K; Nakai, S

    2001-01-01

    Field emission properties of entangled carbon nanotubes were studied for an electron beam source of Cherenkov or Smith-Purcell free electron laser. The cathode was made of carbon nanotubes which were mixed with a very small amount of resin and coated on/in a hollow metallic tube with outer diameter of 0.5 mm. The emission current was as high as 2.2 mA with a fluctuation of <4%. It seems that some entangled nanotubes were frayed under the high electric field and then electrons were emitted mainly from their tips. Reduction of the work function of the carbon nanotubes was observed with the degradation of vacuum pressure in the experimental apparatus.

  20. Multipurpose soft contact lens care in Japan

    Directory of Open Access Journals (Sweden)

    Toshida H

    2012-01-01

    Full Text Available Hiroshi Toshida1,2, Yoshiaki Kadota3, Chikako Suto2, Toshihiko Ohta1, Akira Murakami21Juntendo University Shizuoka Hospital, Department of Ophthalmology, Shizuoka, 2Juntendo University School of Medicine, Department of Ophthalmology, Tokyo, 3Bausch & Lomb Japan Co, Ltd, Research and Development, Tokyo, JapanPurpose: To assess the use of multipurpose lens care products via an online survey conducted among soft contact lens (SCL wearers in Japan.Methods: The subjects were 1000 men and women aged 15–44 years who reported that they cleaned their SCL by using multipurpose solution at least twice a week. Via the internet, they were asked questions about SCL care, the use of a rubbing step when cleaning SCL, cleaning and replacing lens cases, and recommended SCL care methods.Results: Of the 1000 SCL wearers enrolled, 94.3% performed lens care every day lenses were worn, 64.2% reported rubbing the lenses every time, 57.9% rubbed the lenses for at least 10 seconds per side, and 64.7% reported they rubbed the lenses on both sides. Further, 61.2% reported that they had been given an explanation of SCL cleaning at an eye clinic or contact lens store. Only 49.8% of subjects reported that they cleaned the lens case every time and 61.7% replaced the case within 3 months. Only 19.5% had been given an explanation about lens case care. Half of the subjects reported they had been given no recommendation to use specific SCL care products or could not remember whether or not they had. The most common reason for the recommendation was good compatibility with their type of lens.Conclusion: More education is needed in Japan regarding methods of SCL care to ensure correct lens cleaning with inclusion of a rubbing step, as well as sufficient cleaning and replacement of the lens case. Of particular interest is the finding that many subjects were not given an explanation about proper SCL care and lens case cleaning and replacement at the time of lens purchase or

  1. Tear Movement through a Contact Lens of Variable Thickness

    Science.gov (United States)

    Gerhart, Matthew; Anderson, Daniel

    2013-11-01

    This work is on a two-dimensional tear film with a movable porous contact lens. The inclusion of a contact lens into a tear film results in three layers: Pre-Lens Tear Film, Contact Lens, and the Post-Lens Tear Film layers. The interfaces between the contact lens and the tear films are modeled as planar interfaces. There is a free surface interface between the tear film and the outside air. The goal is analyze the effects of the spatial variability of thickness on the Post-Lens Tear Film thickness and on the fluid flow through the Contact Lens layer.

  2. A STUDY ON LENS-INDUCED GLAUCOMA

    Directory of Open Access Journals (Sweden)

    Savithiri Visvanathan

    2017-08-01

    Full Text Available BACKGROUND A study on factors in lens responsible, duration, time of interference and management of increased IOP in lens-induced glaucoma and estimation of aqueous protein level in lens-induced glaucoma. MATERIALS AND METHODS A randomised clinical trial on all cases of phacolytic and phacomorphic glaucoma seen in Coimbatore Medical College Hospital between January to December 2004. RESULTS In this study, males and females had equal prevalence. Out of 50, left eye was affected in 31 cases. Majority were phacolytic and phacomorphic glaucoma. The aqueous protein level was found to be high in lens-induced glaucoma. CONCLUSION Final visual recovery in lens-induced glaucoma is dependent on duration of glaucoma. ECCE or SICS with PCIOL is curative. If duration is more than 7 days, a trabeculectomy has to be added. Periodic checkup of fellow eye is indicated in all cases.

  3. Advances in lenticular lens arrays for visual display

    Science.gov (United States)

    Johnson, R. Barry; Jacobsen, Gary A.

    2005-08-01

    Lenticular lens arrays are widely used in the printed display industry and in specialized applications of electronic displays. In general, lenticular arrays can create from interlaced printed images such visual effects as 3-D, animation, flips, morph, zoom, or various combinations. The use of these typically cylindrical lens arrays for this purpose began in the late 1920's. The lenses comprise a front surface having a spherical crosssection and a flat rear surface upon where the material to be displayed is proximately located. The principal limitation to the resultant image quality for current technology lenticular lenses is spherical aberration. This limitation causes the lenticular lens arrays to be generally thick (0.5 mm) and not easily wrapped around such items as cans or bottles. The objectives of this research effort were to develop a realistic analytical model, to significantly improve the image quality, to develop the tooling necessary to fabricate lenticular lens array extrusion cylinders, and to develop enhanced fabrication technology for the extrusion cylinder. It was determined that the most viable cross-sectional shape for the lenticular lenses is elliptical. This shape dramatically improves the image quality. The relationship between the lens radius, conic constant, material refractive index, and thickness will be discussed. A significant challenge was to fabricate a diamond-cutting tool having the proper elliptical shape. Both true elliptical and pseudo-elliptical diamond tools were designed and fabricated. The plastic sheets extruded can be quite thin (< 0.25 mm) and, consequently, can be wrapped around cans and the like. Fabrication of the lenticular engraved extrusion cylinder required remarkable development considering the large physical size and weight of the cylinder, and the tight mechanical tolerances associated with the lenticular lens molds cut into the cylinder's surface. The development of the cutting tool and the lenticular engraved

  4. A simple template-free approach to TiO2 hollow spheres with enhanced photocatalytic activity.

    Science.gov (United States)

    Yu, Jiaguo; Zhang, Jun

    2010-07-07

    Mesporous anatase-phase TiO(2) hollow spheres with high photocatalytic activity were prepared by hydrothermal treatment and self-transformation of amorphous TiO(2) solid spheres in an NH(4)F aqueous solution. The prepared samples were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, N(2) adsorption-desorption isotherms and UV-vis absorption spectroscopy. The photocatalytic activity was evaluated by photocatalytic oxidation decomposition of acetone in air under UV irradiation. It is found that F(-) plays an essential role in the formation of TiO(2) hollow spheres. F(-) not only induces the hollowing of TiO(2) solid spheres, but also promotes the crystallization of anatase TiO(2) nanocrystals. A possible formation mechanism for the TiO(2) hollow spheres by localized Ostwald ripening or chemically induced self-transformation is proposed based on the experimental observations. Furthermore, the molar ratios of NH(4)F to TiO(2) (R) exhibit a significant influence on the morphology and photocatalytic activity of the TiO(2) samples. The photocatalytic activity of the samples prepared in the presence of NH(4)F is higher than that of TiO(2) sample prepared in pure water and commercial Degussa P25 (P25) powders. Especially, the TiO(2) hollow spheres prepared at R = 1 show the highest photocatalytic activity and the specific rate constant S(k) exceeds that of P25 by a factor of more than two.

  5. Cholesterol Bilayer Domains in the Eye Lens Health: A Review.

    Science.gov (United States)

    Widomska, Justyna; Subczynski, Witold K; Mainali, Laxman; Raguz, Marija

    2017-12-01

    The most unique biochemical characteristic of the eye lens fiber cell plasma membrane is its extremely high cholesterol content, the need for which is still unclear. It is evident, however, that the disturbance of Chol homeostasis may result in damages associated with cataracts. Electron paramagnetic resonance methods allow discrimination of two types of lipid domains in model membranes overloaded with Chol, namely, phospholipid-cholesterol domains and pure Chol bilayer domains. These domains are also detected in human lens lipid membranes prepared from the total lipids extracted from lens cortices and nuclei of donors from different age groups. Independent of the age-related changes in phospholipid composition, the physical properties of phospholipid-Chol domains remain the same for all age groups and are practically identical for cortical and nuclear membranes. The presence of Chol bilayer domains in these membranes provides a buffering capacity for cholesterol concentration in the surrounding phospholipid-Chol domains, keeping it at a constant saturating level and thus keeping the physical properties of the membrane consistent with and independent of changes in phospholipid composition. It seems that the presence of Chol bilayer domains plays an integral role in the regulation of cholesterol-dependent processes in fiber cell plasm membranes and in the maintenance of fiber cell membrane homeostasis.

  6. Cobalt selenide hollow nanorods array with exceptionally high electrocatalytic activity for high-efficiency quasi-solid-state dye-sensitized solar cells

    Science.gov (United States)

    Jin, Zhitong; Zhang, Meirong; Wang, Min; Feng, Chuanqi; Wang, Zhong-Sheng

    2018-02-01

    In quasi-solid-state dye-sensitized solar cells (QSDSSCs), electron transport through a random network of catalyst in the counter electrode (CE) and electrolyte diffusion therein are limited by the grain boundaries of catalyst particles, thus diminishing the electrocatalytic performance of CE and the corresponding photovoltaic performance of QSDSSCs. We demonstrate herein an ordered Co0.85Se hollow nanorods array film as the Pt-free CE of QSDSSCs. The Co0.85Se hollow nanorods array displays excellent electrocatalytic activity for the reduction of I3- in the quasi-solid-state electrolyte with extremely low charge transfer resistance at the CE/electrolyte interface, and the diffusion of redox species within the Co0.85Se hollow nanorods array CE is pretty fast. The QSDSSC device with the Co0.85Se hollow nanorods array CE produces much higher photovoltaic conversion efficiency (8.35%) than that (4.94%) with the Co0.85Se randomly packed nanorods CE, against the control device with the Pt CE (7.75%). Moreover, the QSDSSC device based on the Co0.85Se hollow nanorods array CE presents good long-term stability with only 4% drop of power conversion efficiency after 1086 h one-sun soaking.

  7. Co3O4 based non-enzymatic glucose sensor with high sensitivity and reliable stability derived from hollow hierarchical architecture

    Science.gov (United States)

    Tian, Liangliang; He, Gege; Cai, Yanhua; Wu, Shenping; Su, Yongyao; Yan, Hengqing; Yang, Cong; Chen, Yanling; Li, Lu

    2018-02-01

    Inspired by kinetics, the design of hollow hierarchical electrocatalysts through large-scale integration of building blocks is recognized as an effective approach to the achievement of superior electrocatalytic performance. In this work, a hollow, hierarchical Co3O4 architecture (Co3O4 HHA) was constructed using a coordinated etching and precipitation (CEP) method followed by calcination. The resulting Co3O4 HHA electrode exhibited excellent electrocatalytic activity in terms of high sensitivity (839.3 μA mM‑1 cm‑2) and reliable stability in glucose detection. The high sensitivity could be attributed to the large specific surface area (SSA), ample unimpeded penetration diffusion paths and high electron transfer rate originating from the unique two-dimensional (2D) sheet-like character and hollow porous architecture. The hollow hierarchical structure also affords sufficient interspace for accommodation of volume change and structural strain, resulting in enhanced stability. The results indicate that Co3O4 HHA could have potential for application in the design of non-enzymatic glucose sensors, and that the construction of hollow hierarchical architecture provides an efficient way to design highly active, stable electrocatalysts.

  8. Preparation and crystallization of hollow α-Fe{sub 2}O{sub 3} microspheres following the gas-bubble template method

    Energy Technology Data Exchange (ETDEWEB)

    Valladares, L. de los Santos, E-mail: ld301@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); León Félix, L. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Laboratory of Magnetic Characterization, Instituto de Física, Universidade de Brasília, DF 70910-900, Brasilia (Brazil); Espinoza Suarez, S.M.; Bustamante Dominguez, A.G. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Mitrelias, T.; Holmes, S. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); Moreno, N.O. [Departamento de Física, Universidade Federal de Sergipe, 49100-000, Sao Cristóvao, Sergipe (Brazil); Albino Aguiar, J. [Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife (Brazil); Barnes, C.H.W. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom)

    2016-02-01

    In this work we report the formation of hollow α-Fe{sub 2}O{sub 3} (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO{sub 3}){sub 3}.9H{sub 2}O and citric acid in water by sol–gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250–400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented. - Highlights: • Formation of hollow hematite microspheres by the gas-bubble template method. • This technique does not require hard templates or special conditions of atmosphere. • Annealing promotes the transition magnetite to maghemite to hematite. • Crystallization of the hematite shells increase with annealing temperature.

  9. Core-decomposition-facilitated fabrication of hollow rare-earth silicate nanowalnuts from core-shell structures via the Kirkendall effect

    Science.gov (United States)

    Zhou, Wenli; Zou, Rui; Yang, Xianfeng; Huang, Ningyu; Huang, Junjian; Liang, Hongbin; Wang, Jing

    2015-08-01

    O5 interlayer by facilitating the initial nucleation of the Kirkendall nanovoids and accelerating the interfacial diffusion of Y2O3@SiO2 core@shell. The simple concept developed herein can be employed as a general Kirkendall effect strategy without the assistance of any catalytically active Pt nanocrystals or gold motion for future fabrication of novel hollow nanostructures. Moreover, the photoluminescence properties of rare-earth ion doped hollow Y2SiO5 nanoparticles are researched. Electronic supplementary information (ESI) available: Refined XRD patterns of other control experiments, including using Y2O3@SiO2 instead of YOHCO3@SiO2 to synthesize hollow Y2SiO5 NPs; EDX spectrum of hollow Y2SiO5 nanowalnuts. See DOI: 10.1039/c5nr02684a

  10. Sputtering of hollow atoms from carbon surfaces

    NARCIS (Netherlands)

    Schlatholter, T; Narmann, A; Robin, A; Winters, DFA; Marini, S; Morgenstern, R; Hoekstra, R

    2000-01-01

    We investigated the emission of K Auger electrons from collisions of hydrogenlike ions C(5+), N(6+), and O(7+) with graphite as well as fullerene covered gold surfaces. Besides the quite well understood Anger electrons emitted from the projectile, an extremely high yield of Anger electrons

  11. Co3O4/CoP composite hollow polyhedron: A superior catalyst with dramatic efficiency and stability for the room temperature reduction of 4-nitrophenol

    Science.gov (United States)

    Liu, Xing; Li, Xiangqing; Qin, Lixia; Mu, Jin; Kang, Shi-Zhao

    2018-03-01

    In the present work, Co3O4/CoP composite hollow polyhedrons were prepared and characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and N2 adsorption-desorption isotherms. Then, the catalytic activity of the as-prepared Co3O4/CoP hollow polyhedrons was evaluated for the borohydride-assisted reduction of 4-nitrophenol at room temperature. The results indicate that the as-prepared Co3O4/CoP hollow polyhedrons are an efficient recyclable catalyst for the reduction of 4-nitrophenol. When the 4-nitrophenol initial concentration is 1.0 × 10-4 mol L-1 (100 mL), almost 100% 4-nitrophenol can be reduced within 3 min in the presence of the Co3O4/CoP hollow polyhedrons. The apparent rate constant of the 4-nitrophenol reduction is 1.61 min-1 at room temperature, and the activity factor is about 5.37 × 104 mL min-1 g-1, which is almost two times higher than that over Ag nanoparticles. Finally, the catalytic mechanism was preliminarily discussed. It is found that CoP plays an important role in the catalytic process. Here, CoP serves as active sites, which leads to efficient formation of hydrogen atoms from BH4- and fast electron transfer.

  12. Ultrafine Sn nanoparticles embedded in shell of N-doped hollow carbon spheres as high rate anode for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Peng; Cao, Zhenzhen; Wang, Chao; Zheng, Jiao [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Xu, Xinhua, E-mail: xhxutju@gmail.com [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China)

    2017-05-15

    Highlights: • Dynamic covalent bond in polymeric nanoparticles is used to induce hollow Sn{sup 4+}-MOPs. • Ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn{sup 4+}-MOPs precursor. • The composite exhibits superior cycle stability and rate capacity. - Abstract: A novel reversible interaction in polymeric nanoparticles is used to induce hollow Sn{sup 4+}-MOPs. Then ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn{sup 4+}-MOPs precursor. In this architecture, the N-doped carbon shells can effectively avoid the direct exposure of embedded Sn nanoparticles to the electrolyte and efficiently accommodate the volume change of Sn nanoparticles. Furthermore, the hollow structure of carbon sphere can prevent Sn nanoparticles aggregation over repeated cycling and shorten the diffusion path of both electrons and ions. As a consequence, this N-doped hollow Sn/C anode delivers a reversible capacity of 606 mA h g{sup −1} at a current density of 0.2 A g{sup −1} after 250 cycles and a reversible capacity of 221 mA h g{sup −1} even at a much higher current density of 10 A g{sup −1}, which are much better than those of pure Sn nanoparticles. The desirable cyclic stability and rate capability were attributed to the unique architecture that provided fast pathway for electron transport and simultaneously solved the major issues of Sn-based anodes, such as pulverization, aggregation and loss of electrical contact.

  13. Synthesis and enhanced acetone gas-sensing performance of ZnSnO3/SnO2 hollow urchin nanostructures

    Science.gov (United States)

    Lian, Dandan; Shi, Bing; Dai, Rongrong; Jia, Xiaohua; Wu, Xiangyang

    2017-12-01

    A kind of novel ZnSnO3/SnO2 hollow urchin nanostructure was synthesized by a facile, eco-friendly two-step liquid-phase process. The structure, morphology, and composition of samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption techniques. The results revealed that many tiny needle-like SnO2 nanowires with the average diameter of 5 nm uniformly grew on the surface of the ZnSnO3 hollow microspheres and the ZnSnO3/SnO2 hollow urchin nanostructures with different SnO2 content also were successfully prepared. In order to comprehend the evolution process of the ZnSnO3/SnO2 hollow urchin nanostructures, the possible growth mechanism of samples was illustrated via several experiments in different reaction conditions. Moreover, the gas-sensing performance of as-prepared samples was investigated. The results showed that ZnSnO3/SnO2 hollow urchin nanostructures with high response to various concentration levels of acetone enhanced selectivity, satisfying repeatability, and good long-term stability for acetone detection. Specially, the 10 wt% ZnSnO3/SnO2 hollow urchin nanostructure exhibited the best gas sensitivity (17.03 for 50 ppm acetone) may be a reliable biomarker for the diabetes patients, which could be ascribed to its large specific surface area, complete pore permeability, and increase of chemisorbed oxygen due to the doping of SnO2.

  14. Micron-scale lens array having diffracting structures

    Science.gov (United States)

    Goldberg, Kenneth A

    2013-10-29

    A novel micron-scale lens, a microlens, is engineered to concentrate light efficiently onto an area of interest, such as a small, light-sensitive detector element in an integrated electronic device. Existing microlens designs imitate the form of large-scale lenses and are less effective at small sizes. The microlenses described herein have been designed to accommodate diffraction effects, which dominate the behavior of light at small length scales. Thus a new class of light-concentrating optical elements with much higher relative performance has been created. Furthermore, the new designs are much easier to fabricate than previous designs.

  15. Vibroacoustic response of an eccentric hollow cylinder

    Science.gov (United States)

    Hasheminejad, Seyyed M.; Mousavi-akbarzadeh, Hessam

    2012-07-01

    The linear 3D elasticity theory in conjunction with the classical method of separation of variables and the translational addition theorem for cylindrical wave functions are employed to investigate the three-dimensional steady-state sound radiation characteristics of an arbitrarily thick eccentric hollow cylinder of infinite length, submerged in an unbounded ideal acoustic medium, and subjected to arbitrary time-harmonic on-surface mechanical drives. The spatial Fourier transform along the shell axis and Fourier series expansion in the circumferential direction are utilized to obtain a formal integral expression for the radiated pressure field in the frequency domain. The method of stationary phase is subsequently implemented to evaluate the integral for an observation point in the far field. The analytical results are illustrated with numerical examples in which air-filled water-submerged concentric and eccentric steel cylinders are driven by harmonic concentrated radial and transverse surface loads. Effects of excitation and cylinder eccentricity on the far-field radiated pressure amplitudes/directivities are discussed and contributions from pseudo-Rayleigh, whispering gallery, and axially guided waves are examined through selected spatial dispersion patterns. Limiting cases are considered and the validity of results is established with the aid of a commercial finite element package as well as by comparison with the data in the existing literature.

  16. Reluctance Machine for a Hollow Cylinder Flywheel

    Directory of Open Access Journals (Sweden)

    Magnus Hedlund

    2017-03-01

    Full Text Available A hollow cylinder flywheel rotor with a novel outer rotor switched reluctance machine (SRM mounted on the interior rim is presented, with measurements, numerical analysis and analytical models. Practical experiences from the construction process are also discussed. The flywheel rotor does not have a shaft and spokes and is predicted to store 181 Wh / kg at ultimate tensile strength (UTS according to simulations. The novel SRM is an axial flux machine, chosen due to its robustness and tolerance for high strain. The computed maximum tip speed of the motor at UTS is 1050 m / s . A small-scale proof-of-concept electric machine prototype has been constructed, and the machine inductance has been estimated from measurements of voltage and current and compared against results from analytical models and finite element analysis (FEA. The prototype measurements were used to simulate operation during maximal speed for a comparison towards other high-speed electric machines, in terms of tip speed and power. The mechanical design of the flywheel was performed with an analytical formulation assuming planar stress in concentric shells of orthotropic (unidirectionally circumferentially wound carbon composites. The analytical approach was verified with 3D FEA in terms of stress and strain.

  17. Carbon Hollow Microspheres with a Designable Mesoporous Shell for High-Performance Electromagnetic Wave Absorption.

    Science.gov (United States)

    Xu, Hailong; Yin, Xiaowei; Zhu, Meng; Han, Meikang; Hou, Zexin; Li, Xinliang; Zhang, Litong; Cheng, Laifei

    2017-02-22

    In this work, mesoporous carbon hollow microspheres (PCHMs) with designable mesoporous shell and interior void are constructed by a facile in situ stöber templating approach and a pyrolysis-etching process. The PCHMs are characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, Raman spectroscopy, and nitrogen adsorption and desorption system. A uniform mesoporous shell (pore size 4.7 nm) with a thickness of 55 nm and a cavity size of 345 nm is realized. The composite of paraffin mixed with 20 wt % PCHMs exhibits a minimum reflection coefficient (RCmin) of -84 dB at 8.2 GHz with a sample thickness of 3.9 mm and an effective absorption bandwidth (EAB) of 4.8 GHz below -10 dB (>90% electromagnetic wave is attenuated). Moreover, the composite of phenolic resin mixed with 20 wt % PCHMs exhibits an ultrawide EAB of 8 GHz below -10 dB with a thinner thickness of 2.15 mm. Such excellent electromagnetic wave absorption properties are ascribed to the large carbon-air interface in the mesoporous shell and interior void, which is favorable for the matching of characteristic impedance as compared with carbon hollow microspheres and carbon solid microspheres. Considering the excellent performance of PCHMs, we believe the as-fabricated PCHMs can be promising candidates as highly effective microwave absorbers, and the design philosophy can be extended to other spherical absorbers.

  18. Hollow Pd/MOF Nanosphere with Double Shells as Multifunctional Catalyst for Hydrogenation Reaction.

    Science.gov (United States)

    Wan, Mingming; Zhang, Xinlu; Li, Meiyan; Chen, Bo; Yin, Jie; Jin, Haichao; Lin, Lin; Chen, Chao; Zhang, Ning

    2017-10-01

    A new type of hollow nanostructure featured double metal-organic frameworks shells with metal nanoparticles (MNPs) is designed and fabricated by the methods of ship in a bottle and bottle around the ship. The nanostructure material, hereinafter denoted as Void@HKUST-1/Pd@ZIF-8, is confirmed by the analyses of photograph, transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, inductively coupled plasma, and N 2 sorption. It possesses various multifunctionally structural characteristics such as hollow cavity which can improve mass transfer, the adjacent of the inner HKUST-1 shell to the void which enables the matrix of the shell to host and well disperse MNPs, and an outer ZIF-8 shell which acts as protective layer against the leaching of MNPs and a sieve to guarantee molecular-size selectivity. This makes the material eligible candidates for the heterogeneous catalyst. As a proof of concept, the liquid-phase hydrogenation of olefins with different molecular sizes as a model reaction is employed. It demonstrates the efficient catalytic activity and size-selectivity of Void@HKUST-1/Pd@ZIF-8. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Preparation of Magnetic Hollow Molecularly Imprinted Polymers for Detection of Triazines in Food Samples.

    Science.gov (United States)

    Wang, Aixiang; Lu, Hongzhi; Xu, Shoufang

    2016-06-22

    Novel magnetic hollow molecularly imprinted polymers (M-H-MIPs) were proposed for highly selective recognition and fast enrichment of triazines in food samples. M-H-MIPs were prepared on the basis of multi-step swelling polymerization, followed by in situ growth of magnetic Fe3O4 nanoparticles on the surface of hollow molecularly imprinted polymers (H-MIPs). Transmission electron microscopy and scanning electron microscopy confirmed the successful immobilization of Fe3O4 nanoparticles on the surface of H-MIPs. M-H-MIPs could be separated simply using an external magnet. The binding adsorption results indicated that M-H-MIPs displayed high binding capacity and fast mass transfer property and class selective property for triazines. Langmuir isotherm and pseudo-second-order kinetic models fitted the best adsorption models for M-H-MIPs. M-H-MIPs were used to analyze atrazine, simazine, propazine, and terbuthylazine in corn, wheat, and soybean samples. Satisfactory recoveries were in the range of 80.62-101.69%, and relative standard deviation was lower than 5.2%. Limits of detection from 0.16 to 0.39 μg L(-1) were obtained. When the method was applied to test positive samples that were contaminated with triazines, the results agree well with those obtained from an accredited method. Thus, the M-H-MIP-based dispersive solid-phase extraction method proved to be a convenient and practical platform for detection of triazines in food samples.

  20. Effect of Eu, Tb codoping on the luminescent properties of Y2O3 hollow microspheres

    Science.gov (United States)

    Jiu, Hongfang; Fu, Yuehua; Zhang, Lixin; Sun, Yixin; Wang, Yuanzhong

    2012-12-01

    Y2O3:Eu3+, Tb3+ hollow microspheres are prepared with different doping concentration of Eu3+ and Tb3+ ions and synthesizing temperatures from 700 to 1000 °C via a urea-based homogeneous precipitation technique with colloidal melamine formaldehyde (MF) microspheres as templates followed by a subsequent calcination process. The resulted hollow microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the calcination temperature. The photoluminescence spectra indicate the Eu3+ and Tb3+ co-doped Y2O3 microspheres show five main emission peaks: three at 591, 609 and 629 nm originate from Eu3+ and two at 482 and 541 nm originate from Tb3+, under excitation of 250-340 nm irradiation. The luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu3+ and Tb3+ ions were induced into the Y2O3 lattice and the energy transfer from Tb3+ to Eu3+ ions in these phosphors was found.

  1. Microbial contamination of contact lens storage cases and domestic tap water of contact lens wearers.

    Science.gov (United States)

    Üstüntürk, Miray; Zeybek, Zuhal

    2012-11-01

    Contact lenses have been widely used as an alternative to spectacles both in developed and developing countries. However, under certain circumstances, adverse responses can occur during contact lens wear and several microorganisms--including bacteria, fungi, and free living amoebae--can cause several eye infections in wearers. Extended wear of contact lenses is the major risk factor of eye infections such as microbial keratitis, besides contaminated contact lens storage case, contaminated lens care solutions, and inaccurate contact lens handling. In this study, we collected contact lens storage case and domestic tap water samples from 50 asymptomatic contact lens wearers. We determined that total aerobic mesophilic bacteria were isolated in 45 (90 %), Gram negative rod bacteria were isolated in 20 (40 %), Pseudomonas spp. were isolated in 2 (4 %) and fungi were isolated in 18 (36 %) out of 50 contact lens storage cases. Free living amoebae were not detected in investigated contact lens storage cases. At the same time, out of 50, total aerobic mesophilic bacteria were isolated in 34 (68 %), fungi were isolated in 15 (30 %) and free living amoebae were isolated in 15 (30 %) domestic tap water samples. No Gram-negative rod bacteria and Pseudomonas spp. were detected in investigated water samples. Two contact lens case samples and two tap water samples were excluded from the analysis for Pseudomonas spp. for technical reasons. According to our findings, inadequate contact lens maintenance during lens wear may result in the contamination of contact lens storage cases. This situation can lead to severe eye infections in contact lens wearers over time.

  2. Study on electron beam in a low energy plasma focus

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Muhammad Zubair, E-mail: mzubairkhan-um76@yahoo.com [Plasma Technology Research Center, Department of Physics, Faculty of Science, University Malaya, 50603 Kuala Lumpur, Malaysia and Department of Physics, Federal Urdu University of Arts, Science and Technology, 45320 Islamabad (Pakistan); Ling, Yap Seong; San, Wong Chiow [Plasma Technology Research Center, Department of Physics, Faculty of Science, University Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-03-05

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device.

  3. Contact lens interactions with the tear film.

    Science.gov (United States)

    Mann, Aisling; Tighe, Brian

    2013-12-01

    Biochemical changes brought about by the influence of the contact lens on the tear film are conveniently split into two categories. Firstly, the lens can remove or reduce the levels of specific components in the tear film, and secondly, the lens can augment the tear film, by stimulating the influx of new components or increasing the level of existing components. The most obvious tear film components for study in this context are lipids, proteins, mucins and electrolytes. The interactions are affected by the properties of the lens, the characteristics of the individual wearer and the wear schedule. An additional complicating factor is the fact that the lens is many times thicker than the tear film and any immobilised tear components will be more extensively exposed to oxygen and UV radiation than is the case in the absence of a lens. It is arguably the lipoidal components that are most markedly affected by lens wear, since their immobilisation on the lens surface markedly increases their susceptibility to autoxidative degradation. The limited information that is available highlights the importance of subject specificity and suggests that lipid oxidation phenomena are potentially important in contributing to the 'end of day' discomfort of symptomatic contact lens patients. It is clear that tear lipids, although regarded as relatively inert for many years, are now seen as a reactive and potentially important family of compounds in the search for understanding of contact lens-induced discomfort. The influence of the lens on tear proteins shows the greatest range of complexity. Deposition and denaturation can stimulate immune response, lower molecular weight proteins can be extensively absorbed into the lens matrix and the lens can stimulate cascade or upregulation processes leading either to the generation of additional proteins and peptides or an increase in concentration of existing components. Added to this is the stimulating influence of the lens on vascular

  4. Novel method of assessing delamination of the anterior lens capsule using spectral-domain optical coherence tomography.

    Science.gov (United States)

    Tan, Deborah Kl; Aung, Tin; Perera, Shamira A

    2012-01-01

    Delamination of the anterior lens capsule producing a double-ring sign during continuous curvilinear capsulorhexis is commonly associated with true exfoliation syndrome. Previous studies have concentrated on light- and transmission-electron microscopic features and correlated this with the histopathology of these anterior capsules. To our knowledge, this is the first report of the use of high-resolution spectral-domain optical coherence tomography to delineate delamination of the anterior lens capsule, incidentally detected during cataract surgery.

  5. ELECTRON GUN

    Science.gov (United States)

    Christofilos, N.C.; Ehlers, K.W.

    1960-04-01

    A pulsed electron gun capable of delivering pulses at voltages of the order of 1 mv and currents of the order of 100 amperes is described. The principal novelty resides in a transformer construction which is disposed in the same vacuum housing as the electron source and accelerating electrode structure of the gun to supply the accelerating potential thereto. The transformer is provided by a plurality of magnetic cores disposed in circumferentially spaced relation and having a plurality of primary windings each inductively coupled to a different one of the cores, and a helical secondary winding which is disposed coaxially of the cores and passes therethrough in circumferential succession. Additional novelty resides in the disposition of the electron source cathode filament input leads interiorly of the transformer secondary winding which is hollow, as well as in the employment of a half-wave filament supply which is synchronously operated with the transformer supply such that the transformer is pulsed during the zero current portions of the half-wave cycle.

  6. Anterior chamber intra ocular lens implantation.

    OpenAIRE

    Raju N

    1989-01-01

    The role of A.C. IOL in modern implant surgery has become somewhat debatable, since, the choice procedure to day is undoubtedly an ECCE with a PC lens implant preferably in the capsular bag. Even so, anterior chamber lens implantation has its definite indications. As such it is necessary for the implant surgeon to be familiar with the latest technique in this modality of surgery as well. Many of the complications of earlier rigid model AC IOLs were mainly due to defective lens design. With th...

  7. Foulant analysis of hollow fine fiber (HFF) membranes in Red Sea SWRO plants using membrane punch autopsy (MPA)

    KAUST Repository

    Green, Troy N.

    2017-06-12

    Membrane punch autopsy (MPA) is a procedure for quantitative foulant analysis of hollow fine fiber (HFF) permeators. In the past, quantitative autopsies of membranes were restricted to spiral wound. This procedure was developed at SWCC laboratories and tested on permeators of two commercial Red Sea reverse osmosis plants. For membrane autopsies, stainless steel hollow bore picks were penetrated to membrane cores and fibers extracted for foulant analysis. Quantitative analysis of extracted materials contained inorganic and organic foulants including bacteria. Fourier transform infrared spectroscopy analysis confirmed the presence of organic fouling functional groups and scanning electron microscopy with energy dispersive X-ray spectroscopy in the presence of diatoms and silica most likely not from particulate sand. API analysis revealed the presence of Shewanella and two Vibrio microbial species confirmed by 16S rDNA sequence library. It was observed that fouling content of HFF cellulose triacetate (CTA) membranes were more than 800 times than polyamide spiral wound membranes.

  8. Clarification of Orange Press Liquors by PVDF Hollow Fiber Membranes

    Directory of Open Access Journals (Sweden)

    Silvia Simone

    2016-01-01

    Full Text Available Press liquors are typical by-products of the citrus juice processing characterized by a high content of organic compounds and associated problems of environmental impact, which imply high treatment costs. However, these wastes contain a great number of health promoting substances, including fibers, carotenoids and phenolic compounds (mainly flavonoids, whose recovery against waste-destruction technologies is very attractive for new business opportunities. In this work, the clarification of orange press liquor by using microfiltration (MF membranes is studied as a preliminary step to obtain a permeate stream enriched in antioxidant compounds which can be further processed to produce extracts of nutraceutical and/or pharmaceutical interest. MF poly(vinylidene fluoride (PVDF hollow fibers were prepared by the dry/wet spinning technique. A series of fibers was produced from the same polymeric dope, in order to investigate the effect of selected spinning parameters, i.e., bore fluid composition and flowrate, on their properties. The morphology of the produced fibers was analyzed by Scanning Electron Microscopy (SEM. Fibers were further characterized for their mechanical properties, porosity, bubble point, pore size distribution and pure water permeability (PWP. Some of the produced fibers exhibited high permeability (pure water permeability ~530 L/m2·h·bar, coupled to good mechanical resistance and pore size in the range of MF membranes. These fibers were selected and used for the clarification of press liquor from orange peel processing. In optimized operating conditions, the selected fibers produced steady-state fluxes of about 41 L/m2·h with rejections towards polyphenols and total antioxidant activity of 4.1% and 1.4%, respectively.

  9. Electron caustic lithography

    Directory of Open Access Journals (Sweden)

    S. M. Kennedy

    2012-06-01

    Full Text Available A maskless method of electron beam lithography is described which uses the reflection of an electron beam from an electrostatic mirror to produce caustics in the demagnified image projected onto a resist–coated wafer. By varying the electron optics, e.g. via objective lens defocus, both the morphology and dimensions of the caustic features may be controlled, producing a range of bright and tightly focused projected features. The method is illustrated for line and fold caustics and is complementary to other methods of reflective electron beam lithography.

  10. 16 CFR 315.6 - Expiration of contact lens prescriptions.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Expiration of contact lens prescriptions. 315.6 Section 315.6 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS CONTACT LENS RULE § 315.6 Expiration of contact lens prescriptions. (a) In general. A contact lens prescription shall expire: (1) On the date...

  11. 21 CFR 886.5844 - Prescription spectacle lens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Prescription spectacle lens. 886.5844 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5844 Prescription spectacle lens. (a) Identification. A prescription spectacle lens is a glass or plastic device that is a lens intended to be worn by...

  12. Hollow proppants and a process for their manufacture

    Science.gov (United States)

    Jones, Arfon H.; Cutler, Raymond A.

    1985-01-01

    Hollow, fine-grained ceramic proppants are less expensive and improve fracture control when compared to conventional proppants (dense alumina, mullite, bauxite, zirconia, etc.). Hollow proppants of the present invention have been fabricated by spray drying, followed by sintering in order to obtain a dense case and a hollow core. These proppants generally have high sphericity and roundness (Krumbein sphericity and roundness greater than 0.8), have diameters on average between 2250 and 125 .mu.m, depending on proppant size required, and have strength equal to or greater than that of sand. The hollow core, the size of which can be controlled, permits better fracture control in hydraulic fracturing treatments since the proppant can be transported in lower viscosity fluids. Hollow proppants produced at the same cost/weight as conventional proppants also provide for lower costs, since less weight is required to fill the same volume. The fine-grained (preferably less than 5 .mu.m in diameter) ceramic case provides the strength necessary to withstand closure stresses and prevent crushing.

  13. Synthesis, Properties, and Applications of Hollow Micro-/Nanostructures.

    Science.gov (United States)

    Wang, Xiaojing; Feng, Ji; Bai, Yaocai; Zhang, Qiao; Yin, Yadong

    2016-09-28

    In this Review, we aim to provide an updated summary of the research related to hollow micro- and nanostructures, covering both their synthesis and their applications. After a brief introduction to the definition and classification of the hollow micro-/nanostructures, we discuss various synthetic strategies that can be grouped into three major categories, including hard templating, soft templating, and self-templating synthesis. For both hard and soft templating strategies, we focus on how different types of templates are generated and then used for creating hollow structures. At the end of each section, the structural and morphological control over the product is discussed. For the self-templating strategy, we survey a number of unconventional synthetic methods, such as surface-protected etching, Ostwald ripening, the Kirkendall effect, and galvanic replacement. We then discuss the unique properties and niche applications of the hollow structures in diverse fields, including micro-/nanocontainers and reactors, optical properties and applications, magnetic properties, energy storage, catalysis, biomedical applications, environmental remediation, and sensors. Finally, we provide a perspective on future development in the research relevant to hollow micro-/nanostructures.

  14. Microwave-hydrothermal preparation and visible-light photoactivity of plasmonic photocatalyst Ag-TiO2 nanocomposite hollow spheres.

    Science.gov (United States)

    Xiang, Quanjun; Yu, Jiaguo; Cheng, Bei; Ong, H C

    2010-06-01

    Visible-light-driven plasmonic photocatalyst Ag-TiO(2) nanocomposite hollow spheres are prepared by a template-free chemically-induced self-transformation strategy under microwave-hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N(2) adsorption-desorption isotherms, X-ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of .OH radicals on the surface of visible-light illuminated TiO(2) was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as-prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible-light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO(2) hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag-TiO(2) nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible-light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO(2) and commercial Degussa P25 (P25) powders. Especially, the as-prepared Ag-TiO(2) nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium (R) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2.

  15. The photocatalytic properties of hollow (GaN)1-x(ZnO)x composite nanofibers synthesized by electrospinning

    Science.gov (United States)

    Wang, Ding; Zhang, Minglu; Zhuang, Huaijuan; Chen, Xu; Wang, Xianying; Zheng, Xuejun; Yang, Junhe

    2017-02-01

    (GaN)1-x(ZnO)x composite nanofibers with hollow structure were prepared by initial electrospinning, and the subsequent calcination and nitridation. The structure and morphology characteristics of samples were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The characterization results showed the phase transition from ZnGa2O4 to (GaN)1-x(ZnO)x solid-solution under ammonia atmosphere. The preparation conditions were explored and the optimum nitridation temperature and holding time are 750 °C and 2 h, respectively. The photocatalytic properties of (GaN)1-x(ZnO)x with different Ga:Zn atomic ratios were investigated by degrading Rhodamine B under the visible light irradiation. The photocatalytic activity sequence is (GaN)1-x(ZnO)x (Ga:Zn = 1:2) > (GaN)1-x(ZnO)x (Ga:Zn = 1:3) > ZnO nanofibers > (GaN)1-x(ZnO)x (Ga:Zn = 1:4) > (GaN)1-x(ZnO)x (Ga:Zn = 1:1). The photocatalytic mechanism of the (GaN)1-x(ZnO)x hollow nanofibers was further studied by UV-vis diffuse reflectance spectra. The excellent photocatalytic performance of (GaN)1-x(ZnO)x hollow nanofibers was attributed to the narrow band gap and high surface area of porous nanofibers with hollow structure.

  16. High capacity and high rate capability of nitrogen-doped porous hollow carbon spheres for capacitive deionization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Shanshan; Yan, Tingting; Wang, Hui; Chen, Guorong; Huang, Lei; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong, E-mail: dszhang@shu.edu.cn

    2016-04-30

    Graphical abstract: - Highlights: • The nitrogen-doped porous hollow carbon spheres were prepared. • The obtained materials have a good capacitive deionization performance. • The electrodes show high salt adsorption rate and good regeneration performance. - Abstract: In this work, nitrogen-doped porous hollow carbon spheres (N-PHCS) were well prepared by using polystyrene (PS) spheres as hard templates and dopamine hydrochloride as carbon and nitrogen sources. Field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the N-PHCS have a uniform, spherical and hollow structure. Nitrogen adsorption–desorption analysis shows that the N-PHCS have a high specific area of 512 m{sup 2}/g. X-ray photoelectron spectroscopy result reveals that the nitrogen doping amount is 2.92%. The hollow and porous structure and effective nitrogen doping can contribute to large accessible surface area, efficient ion transport and good conductivity. In the electrochemical tests, we can conclude that the N-PHCS have a high specific capacitance value, a good stability and low inner resistance. The N-PHCS electrodes present a high salt adsorption capacity of 12.95 mg/g at a cell voltage of 1.4 V with a flow rate of 40 mL/min in a 500 mg/L NaCl aqueous solution. Moreover, the N-PHCS electrodes show high salt adsorption rate and good regeneration performance in the CDI process. With high surface specific area and effective nitrogen doping, the N-PHCS is promising to the CDI and other electrochemical applications.

  17. Contact lens compliance among a group of young, university-based lens users in South India.

    Science.gov (United States)

    Noushad, Babu; Saoji, Yeshwant; Bhakat, Premjit; Thomas, Jyothi

    2012-01-01

    To investigate the rate of compliance with the soft contact lens care and maintenance procedures with a focus on contact lens wearing habits, cleaning and disinfecting procedures, and maintenance of lens care accessories in a group of young, university-based contact lens wearers Two hundred and sixteen young soft contact lens wearers with an age range of 18-22 years were selected conveniently from the student population of Manipal University, Manipal, India. After receiving informed consent from the participants, their level of compliance with contact lenses was assessed using a questionnaire. The mean (±SD) age of the participants was 21.86±2.35 years. Out of 216 subjects, only 34% of the lens users were identified to be compliant with the least level of compliance observed in the maintenance of lens care accessories. Conventional users showed significantly (p=0.001) better level of compliance compared to disposable wearers and so did the users who acquired their lenses from clinicians (p=0.001) compared to over-the-counter lens receipt. The gender (p=0.496) and years of experience in contact lens use (p=0.142) did not show any statistically significant difference in the level of compliance. This study demonstrated that non-compliance with lens care procedures among a group of young, university-based soft contact lens wearers is common. The results indicated that all subjects had some degree of non-compliance and the least level of compliance observed in the care of lens accessories.

  18. Tear film physiology and contact lens wear. II. Contact lens-tear film interaction.

    Science.gov (United States)

    Holly, F J

    1981-04-01

    The successful fitting of contact lenses requires the practitioner to take into account many properties of the specific lens type used but the practitioner must also understand patient factors including tear properties, use of appropriate solutions, procedures for lens cleaning, and efficiency of blinking. Selection of appropriate patients, selection of lens type, proper fitting, good maintenance, and training and monitoring of patients increase the probability of achieving success.

  19. Efficient small molecular organic light emitting diode with graphene cathode covered by a Sm layer with nano-hollows and n-doped by Bphen:Cs2CO3 in the hollows

    Science.gov (United States)

    Yao, Li; Li, Lei; Qin, Laixiang; Ma, Yaoguang; Wang, Wei; Meng, Hu; Jin, Weifeng; Wang, Yilun; Xu, Wanjin; Ran, Guangzhao; You, Liping; Qin, Guogang

    2017-03-01

    Graphene is a favorable candidate for electrodes of organic light emitting diodes (OLEDs). Graphene has quite a high work function of ˜4.5 eV, and has been extensively studied when used as anodes of OLEDs. In order to use graphene as a cathode, the electron injection barrier between the graphene cathode and the electron transport layer has to be low enough. Using 4,7-diphenyl-1,10-phenanthroline (Bphen):Cs2CO3 to n-dope graphene is a very good method, but the electron injection barrier between the n-doped graphene and Bphen:Cs2CO3 is still too high to be ˜1.0 eV. In this work, in order to further reduce the electron injection barrier, a novel method is suggested. On the graphene cathode, a Sm layer with a lot of nano-hollows, and subsequently a layer of Bphen:Cs2CO3, are deposited. The Bphen:Cs2CO3 can n-dope graphene in the nano-hollows, and the Fermi level of the graphene rises. The nano Sm layer is very easily oxidized. Oxygen adsorbed on the surface of graphene may react with Sm to form an O--Sm+ dipole layer. On the areas of the Sm oxide dipole layer without nano-hollows, the electron injection barrier can be further lowered by the dipole layer. Electrons tend to mainly inject through the lower electron barrier where the dipole layer exists. Based on this idea, an effective inverted small molecular OLED with the structure of graphene/1 nm Sm layer with a lot of nano-hollows/Bphen:Cs2CO3/Alq3:C545T/NPB/MoO3/Al is presented. The maximum current efficiency and maximum power efficiency of the OLED with a 1 nm Sm layer are about two and three times of those of the reference OLED without any Sm layer, respectively.

  20. Improved Gene Transfer with Functionalized Hollow Mesoporous Silica Nanoparticles of Reduced Cytotoxicity

    Directory of Open Access Journals (Sweden)

    Zhengwen Zhan

    2017-06-01

    Full Text Available Gene therapy is a promising strategy for treatment of genetically caused diseases. Successful gene delivery requires an efficient carrier to transfer the desired gene into host cells. Recently, mesoporous silica nanoparticles (MSNs functionalized with 25 kD polyethyleneimine (PEI were extensively used as gene delivery carriers. However, 25 kD PEI could significantly reduce the safety of the modified MSNs although it is efficient for intracellular delivery of nucleic acids. In addition, limited drug loading remains a challenge for conventional MSNs drug carriers. Hollow mesoporous silica nanoparticles (HMSNs with high pore volume, tunable pore size, and excellent biocompatibility are attractive alternatives. To make them more efficient, a less toxic 1.8 kD PEI polymer was used to functionalize the HMSNs which have large pore size (~10 nm and form PEI-HMSNs. Scanning and transmission electron microscopic images showed that HMSNs were spherical in shape and approximately 270 nm in diameter with uniform hollow nanostructures. The maximum loading capacity of green fluorescent protein labeled DNA (GFP-DNA in PEI-HMSNs was found to be 37.98 mg/g. The loading capacity of PEI-HMSNs was nearly three-fold higher than those of PEI modified solid nanoparticles, indicating that both hollow and large pores contributed to the increase in DNA adsorption. The transfection of GFP-DNA plasmid loaded in PEI-HMSNs was increased two-fold in comparison to that of 25 kD PEI. MTT assays in Lovo cells showed that the cell viability was more than 85% when the concentration of PEI-HMSNs was 120 µg/mL, whereas the cell viability was less than 20% when the 25 kD PEI was used at the same concentration. These results indicated that PEI-HMSNs could be used as a delivery system for nucleic acids due to good biocompatibility, high gene loading capacity, and enhanced gene transfer efficiency.

  1. Behaviour of `free-standing' hollow Au nanocages at finite temperatures: a BOMD study

    Science.gov (United States)

    Joshi, Krati; Krishnamurty, Sailaja

    2015-10-01

    Finite-temperature behaviour of a hollow golden cage (HGC) plays a crucialrole in its potential applications as a catalyst, drug delivery agent, contrasting agent and so on. This physico-chemical property of HGCs is not well understood so far. In that context, Born-Oppenheimer molecular dynamics (BOMD) simulations are performed on a well-known 'free-standing' HGC. The cluster considered in this study is the ground state Au18 cluster (a cage with a diameter of about >5.5 Å). The results thus obtained are compared with the BOMD simulation results reported earlier on Au32 icosahedron cage, a conformation with a diameter of nearly. The sphericity of both the clusters is studied using a shape deformation parameter as a function of time and temperature. These results are supplemented by radial distribution function at various temperatures. The observations and analysis of results indicate that, both the clusters retain an HGC conformation from 300 to 400 K, admitting structural fluxionality by the Au18 cluster. Remarkably, the Au18 cluster is able to maintain its hollowness and sphericity up to a high temperature of 1000 K. Underlying structural and electronic properties influencing the individualistic behaviour of cages are highlighted. Composition of the frontier molecular orbitals and the charge distribution play a crucial role in the finite-temperature behaviour of the Au cages. The conclusions are supplemented by supporting calculations on another degenerate ground state Au18 hollow cage and a well-known pyramidal Au18 cage at 300 and 400 K.

  2. Bionic intraocular lens with variable focus and integrated structure

    Science.gov (United States)

    Liang, Dan; Wang, Xuan-Yin; Du, Jia-Wei; Xiang, Ke

    2015-10-01

    This paper proposes a bionic accommodating intraocular lens (IOL) for ophthalmic surgery. The designed lens has a solid-liquid mixed integrated structure, which mainly consists of a support ring, elastic membrane, rigid lens, and optical liquid. The lens focus can be adjusted through the deformation of the lens front surface when compressed. The integrated structure of the IOL is presented, as well as a detailed description of the lens materials and fabrication process. Images under different radial pressures are captured, and the lens deformation process, accommodating range, density, and optical property are analyzed. The designed lens achieves a 14.6 D accommodating range under a radial pressure of 51.4 mN and a 0.24 mm alteration of the lens outer radius. The deformation property of the lens matches well with the characteristic of the eye and shows the potential to help patients fully recover their vision accommodation ability after the cataract surgery.

  3. Family Bovidae (Hollow-horned Ruminants)

    Science.gov (United States)

    Groves, Colin P.; Leslie, David M.; Huffman, Brent A.; Valdez, Raul; Habibi, Khushal; Weinberg, Paul; Burton, James; Jarman, Peter; Robichaud, William

    2015-01-01

    Probably the single most eye-catching aspect of the current volume is the explosion of species recognized in the family Bovidae (Hollow-horned Ruminants). In 2005, the third edition of Mammal Species of the World listed 143 species in 50 genera of Bovidae. That list, prepared by the late Peter Grubb, was somewhat traditional and provisional, as he was engaged with his long-time colleague, Colin Groves, in a substantial revision of ungulate taxonomy. Their work, which will be published later this year, is the culmination of years of study of this important and wide-ranging family by these two venerable authorities. Colin Groves is the lead author for Bovidae in this volume of HMW, and in it we recognize all 279 species in 54 genera that are documented in his and Peter Grubb’s ground-breaking work.At the root of this expanded number of recognized species is our changing view of the modern species concept. Like a growing number of taxonomists, Groves favors a phylogenetic species concept, which he defines as the smallest population or aggregation of populations that has fixed heritable differences from other such populations or aggregations. This is in contrast to the traditional biological species concept, which requires reproductive isolation between such populations. The difficulty in determining that reproductive isolation led to an underrepresentation of the number of species in many groups. Clearly there remain problems in determining which differences between populations are heritable, and the system used here undoubtedly will continue to be tweaked as our understanding grows. For now, this greatly expanded version of Bovidae species limits seems the best answer. One of the goals of HMW is to provide an up-to-date summary of the conservation status for every species of mammal, and this expanded species concept better enables us to explore the true conservation situation of each.

  4. Bilateral lens luxation and intracapsular lens extractions in a Matshchie's tree kangaroo.

    Science.gov (United States)

    McLean, Nancy Johnstone; Zimmerman, Ralph

    2015-01-01

    An adult, female, captive, Matshchie's tree kangaroo was diagnosed with an anterior lens luxation in the right eye and a lens subluxation in the left eye. Both eyes were treated surgically with intracapsular lens extractions. A 360° rhegmatogenous retinal detachment was diagnosed 6 months postoperatively in the left eye. Aphakic vision was maintained in the right eye 9 months postoperatively. Based on family history and the lack of antecedent ocular disease, the lens luxations were presumed to be inherited and veterinarians should be aware of this condition within the captive tree kangaroo population. © 2014 American College of Veterinary Ophthalmologists.

  5. Contractual considerations in contact lens practice.

    Science.gov (United States)

    Classé, J G

    1986-03-01

    The use of forms in contact lens practice can save time, promote patient education, and reduce the opportunity for legal or economic disputes. The most commonly employed forms are those for contact lens fitting agreements, instructions for care and maintenance of lenses, prepaid service agreements, clinical investigations of investigatory lenses or solutions, and for extended wear patients. Sample forms are utilized for purposes of illustration.

  6. Small capsulotomy and great implant lens.

    Science.gov (United States)

    Budo, C; Montanus, F

    1991-01-01

    The envelope technique provokes in all cases a rupture of the zonules. With capsulorhexis, the advantages of working inside the envelope are lost, but the zonules are better protected. The capsulokleisis--or similar capsulotomies--combines the advantages of both systems. The Miyake technique indicates that the ideal lens for the capsular bag is a circular lens filling completely the capsular bag like the phacodrop.

  7. Lens Design Using Group Indices of Refraction

    Science.gov (United States)

    Vaughan, A. H.

    1995-01-01

    An approach to lens design is described in which the ratio of the group velocity to the speed of light (the group index) in glass is used, in conjunction with the more familiar phase index of refraction, to control certain chromatic properties of a system of thin lenses in contact. The first-order design of thin-lens systems is illustrated by examples incorporating the methods described.

  8. Ultrafine Sn nanoparticles embedded in shell of N-doped hollow carbon spheres as high rate anode for lithium-ion batteries

    Science.gov (United States)

    Dou, Peng; Cao, Zhenzhen; Wang, Chao; Zheng, Jiao; Xu, Xinhua

    2017-05-01

    A novel reversible interaction in polymeric nanoparticles is used to induce hollow Sn4+-MOPs. Then ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn4+-MOPs precursor. In this architecture, the N-doped carbon shells can effectively avoid the direct exposure of embedded Sn nanoparticles to the electrolyte and efficiently accommodate the volume change of Sn nanoparticles. Furthermore, the hollow structure of carbon sphere can prevent Sn nanoparticles aggregation over repeated cycling and shorten the diffusion path of both electrons and ions. As a consequence, this N-doped hollow Sn/C anode delivers a reversible capacity of 606 mA h g-1 at a current density of 0.2 A g-1 after 250 cycles and a reversible capacity of 221 mA h g-1 even at a much higher current density of 10 A g-1, which are much better than those of pure Sn nanoparticles. The desirable cyclic stability and rate capability were attributed to the unique architecture that provided fast pathway for electron transport and simultaneously solved the major issues of Sn-based anodes, such as pulverization, aggregation and loss of electrical contact.

  9. Micelles of poly(styrene-b-2-vinylpyridine-b-ethylene oxide) with blended polystyrene core and their application to the synthesis of hollow silica nanospheres.

    Science.gov (United States)

    Liu, Dian; Sasidharan, Manickam; Nakashima, Kenichi

    2011-06-15

    Core-shell-corona (CSC) micelles of asymmetric triblock copolymer, poly(styrene-b-2-vinylpyridine-b-ethylene oxide) (PS-PVP-PEO), containing polystyrene homopolymer (homo-PS) in the core were successfully prepared in aqueous media. The influence of homo-PS contents over the formation of the micelles was investigated thoroughly by various techniques such as dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence spectroscopy. It was found that the size of the PS core of the micelle was increased by the addition of homo-PS as observed by DLS and TEM techniques. The SEM and TEM measurements confirm the spherical morphology of the micelles and enlargement of PS core over the addition of homo-PS. The increase in the PS core volume of the PS-PVP-PEO micelles is attributed to the insertion of homo-PS in the PS core. The micelles have also been demonstrated as facile soft templates for synthesis of hollow silica nanospheres. The average diameter of the spherical hollow particles could be tuned between 30.6 and 38.8 nm with cavity sizes ranging from 20.7 to 28.5 nm using tetramethoxysilane as silica precursors under mild acidic conditions. The facile synthesis of hollow silica using the CSC micelles with different homo-PS contents indicates that the hollow void size can be controlled within a range of several nanometers. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Uniform Fe{sub 3}O{sub 4}-PANi/PS composite spheres with conductive and magnetic properties and their hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xiaocong, E-mail: wangxc@tust.edu.c [Tianjin University of Science and Technology, College of Science (China); Tang Saide [Tianjin University, College of Materials Science and Engineering (China); Liu Jing [Tianjin University of Science and Technology, College of Science (China); He Ziqiong [Tianjin Medical College (China); An Lijuan; Zhang Chenxi; Hao Jingmei [Tianjin University of Science and Technology, College of Science (China); Feng Wei [Tianjin University, College of Materials Science and Engineering (China)

    2009-05-15

    Core-shell multifunctional composite spheres consisting of Fe{sub 3}O{sub 4}-polyaniline (PANi) shell and polystyrene (PS) core were fabricated using core-shell-structured sulfonated PS spheres (with uniform diameter of 250 nm) as templates. PANi was doped in situ by sulfonic acid resulting the composite spheres are well conductive. Dissolved with solvent, PS cores were removed from the core-shell composite spheres and hollow Fe{sub 3}O{sub 4}-PANi spheres were obtained. Removing the PANi and PS components by calcinations produced hollow Fe{sub 3}O{sub 4} spheres. The cavity size of the hollow spheres was uniformly approximate to 190 nm and the shell thickness was 30 nm. The cavity size and the shell thickness can be synchronously controlled by varying the sulfonation time of the PS templates. The shell thickness in size range was of 20-86 nm when the sulfonation time was changed from 1 to 4 h. These resulting spheres could be arranged in order by self-assembly of the templates. Both the Fe{sub 3}O{sub 4}-PANi/PS composite spheres and the hollow Fe{sub 3}O{sub 4} spheres exhibit a super-paramagnetic behavior. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder scattering were used to characterize these as-prepared spheres.

  11. SiO2/ZnO Composite Hollow Sub-Micron Fibers: Fabrication from Facile Single Capillary Electrospinning and Their Photoluminescence Properties.

    Science.gov (United States)

    Song, Guanying; Li, Zhenjiang; Li, Kaihua; Zhang, Lina; Meng, Alan

    2017-02-24

    In this work, SiO2/ZnO composite hollow sub-micron fibers were fabricated by a facile single capillary electrospinning technique followed by calcination, using tetraethyl orthosilicate (TEOS), polyvinylpyrrolidone (PVP) and ZnO nanoparticles as raw materials. The characterization results of the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) spectra indicated that the asprepared composite hollow fibers consisted of amorphous SiO2 and hexagonal wurtzite ZnO. The products revealed uniform tubular structure with outer diameters of 400-500 nm and wall thickness of 50-60 nm. The gases generated and the directional escaped mechanism was proposed to illustrate the formation of SiO2/ZnO composite hollow sub-micron fibers. Furthermore, a broad blue emission band was observed in the photoluminescence (PL) of SiO2/ZnO composite hollow sub-micron fibers, exhibiting great potential applications as blue light-emitting candidate materials.

  12. SiO2/ZnO Composite Hollow Sub-Micron Fibers: Fabrication from Facile Single Capillary Electrospinning and Their Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Guanying Song

    2017-02-01

    Full Text Available In this work, SiO2/ZnO composite hollow sub-micron fibers were fabricated by a facile single capillary electrospinning technique followed by calcination, using tetraethyl orthosilicate (TEOS, polyvinylpyrrolidone (PVP and ZnO nanoparticles as raw materials. The characterization results of the scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FT-IR spectra indicated that the asprepared composite hollow fibers consisted of amorphous SiO2 and hexagonal wurtzite ZnO. The products revealed uniform tubular structure with outer diameters of 400–500 nm and wall thickness of 50–60 nm. The gases generated and the directional escaped mechanism was proposed to illustrate the formation of SiO2/ZnO composite hollow sub-micron fibers. Furthermore, a broad blue emission band was observed in the photoluminescence (PL of SiO2/ZnO composite hollow sub-micron fibers, exhibiting great potential applications as blue light-emitting candidate materials.

  13. Hollow volcanic tumulus caves of Kilauea Caldera, Hawaii County, Hawaii

    Directory of Open Access Journals (Sweden)

    William R. Halliday

    1998-01-01

    Full Text Available In addition to lava tube caves with commonly noted features, sizable subcrustal spaces of several types exist on the floor of Kilauea Caldera. Most of these are formed by drainage of partially stabilized volcanic structures enlarged or formed by injection of very fluid lava beneath a plastic crust. Most conspicuous are hollow tumuli, possibly first described by Walker in 1991. Walker mapped and described the outer chamber of Tumulus E-I Cave. Further exploration has revealed that it has a hyperthermic inner room beneath an adjoining tumulus with no connection evident on the surface. Two lengthy, sinuous hollow tumuli also are present in this part of the caldera. These findings support Walkers conclusions that hollow tumuli provide valuable insights into tumulus-forming mechanisms, and provide information about the processes of emplacement of pahoehoe sheet flows.

  14. Hollow Silica: A novel Material for Methane Storage

    Directory of Open Access Journals (Sweden)

    Chari Vangala Dhanunjana

    2015-11-01

    Full Text Available Methane gas storage in the form of Methane Hydrate (MH in hollow silica was studied and compared with solid silica and pure water systems. The gas hydrate growth/dissociation was monitored by following the pressure (gas intake – temperature variations in a classical isochoric process. The effect of stirring on the hydrate formation kinetics and yield was clearly evidenced in the case of solid and pure water systems, whereas it did not show any influence in hollow silica; and in fact, the yields remained identical in both stirring and non-stirring experiments. Approximately 3.6 m.mol of methane per gram of water was consumed as MH in the hollow silica matrix and the formation kinetics was extremely fast (~180 min. However, the methane gas conversion into MH in solid silica and pure water systems was ~ 10 times higher in a stirred reactor when compared with a non-stirred system.

  15. Fabrication of Polyacrylonitrile Hollow Fiber Membranes from Ionic Liquid Solutions

    KAUST Repository

    Kim, Dooli

    2015-10-08

    The interest in green processes and products has increased to reduce the negative impact of many industrial processes to the environment. Solvents, which play a crucial role in the fabrication of membranes, need to be replaced by sustainable and less toxic solvent alternatives for commonly used polymers. The purpose of this study is the fabrication of greener hollow fiber membranes based on polyacrylonitrile (PAN), substituting dimethylformamide (DMF) by less toxic mixtures of ionic liquids (IL) and dimethylsulfoxide (DMSO). A thermodynamic analysis was conducted, estimating the Gibbs free energy of mixing to find the most convenient solution compositions. Hollow fiber membranes were manufactured and optimized. As a result, a uniform pattern and high porosity were observed in the inner surface of the membranes prepared from the ionic liquid solutions. The membranes were coated with a polyamide layer by interfacial polymerization the hollow fiber membranes were applied in forward osmosis experiments by using sucrose solutions as draw solution.

  16. Sharp tipped plastic hollow microneedle array by microinjection moulding

    Science.gov (United States)

    Yung, K. L.; Xu, Yan; Kang, Chunlei; Liu, H.; Tam, K. F.; Ko, S. M.; Kwan, F. Y.; Lee, Thomas M. H.

    2012-01-01

    A method of producing sharp tipped plastic hollow microneedle arrays using microinjection moulding is presented in this paper. Unlike traditional approaches, three mould inserts were used to create the sharp tips of the microneedles. Mould inserts with low surface roughness were fabricated using a picosecond laser machine. Sharp tipped plastic hollow microneedles 500 µm in height were fabricated using a microinjection moulding machine developed by the authors’ group. In addition, the strength of the microneedle was studied by simulation and penetration experiments. Results show that the microneedles can penetrate into skin, delivering liquid successfully without any breakage or severe deformation. Techniques presented in this paper can be used to fabricate sharp tipped plastic hollow microneedle arrays massively with low cost.

  17. Hollow-core photonic-crystal fibres for laser dentistry

    Energy Technology Data Exchange (ETDEWEB)

    Konorov, Stanislav O [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Mitrokhin, Vladimir P [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Fedotov, Andrei B [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Sidorov-Biryukov, Dmitrii A [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Beloglazov, Valentin I [Technology and Equipment for Glass Structures Institute, pr. Stroitelei 1, 410044 Saratov (Russian Federation); Skibina, Nina B [Technology and Equipment for Glass Structures Institute, pr. Stroitelei 1, 410044 Saratov (Russian Federation); Wintner, Ernst [Institut fuer Photonik, Technische Universitaet Wien, Gusshausstrasse 27/387, 1040 Wien (Austria); Scalora, Michael [Weapons Sciences Directorate, US Army Aviation and Missile Command Huntsville, AL 35898-5000 (United States); Zheltikov, Aleksei M [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation)

    2004-04-07

    Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 {mu}m Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 {mu}m and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 {mu}m laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

  18. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    2017-01-01

    Purpose – Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60 and 120 min found...... in most national building regulations. The paper aims to present a detailed analysis of the mechanisms responsible for the loss of loadbearing capacity of hollow-core slabs when exposed to fire. Design/methodology/approach – Furthermore, it compares theoretica calculation and assessment according...... to the structural codes with data derived from a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Findings – Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. Originality...

  19. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Giuliani, Luisa; Sørensen, Lars Schiøtt

    2016-01-01

    Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60- and 120 minutes found in most...... national building regulations. The paper presents a detailed analysis of the mechanisms responsible for the loss of load-bearing capacity of hollow-core slabs when exposed to fire. Furthermore, it compares theoretical calculation and assessment according to the structural codes with data derived from...... a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. For the first time the mechanisms responsible for loss of load...

  20. Strain sensor based on hollow microsphere Fabry-Perot cavity

    Science.gov (United States)

    Monteiro, Catarina S.; Silva, Susana O.; Frazão, Orlando

    2017-08-01

    Fusion splicing technique was explored for the fabrication of two sensing structures based on hollow microsphere Fabry- Perot cavity. The first sensor proposed was fabricated with a hollow microsphere tip, working as a probe sensor. This structure was studied for lateral load pressure, yielding a 1.56 +/- 0.01 nm/N sensitivity. The second sensing structure relied on an in-line hollow microsphere, which allowed the detection of lateral load, with a sensitivity of 2.62 +/- 0.02 nm/N. Furthermore, the proposed structure enabled strain sensing, with a sensitivity of 4.66 +/- 0.03 pm/μɛ. The two sensing structures were subjected to temperature, presenting low thermal cross-sensitivity.

  1. Pressure effects in hollow and solid iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Silva, N.J.O., E-mail: nunojoao@ua.pt [Departamento de Física and CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Saisho, S.; Mito, M. [Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Millán, A.; Palacio, F. [Instituto de Ciencia de Materiales de Aragón, CSIC - Universidad de Zaragoza. Departamento de Física de la Materia Condensada, Facultad de Ciencias, 50009 Zaragoza (Spain); Cabot, A. [Universitat de Barcelona and Catalonia Energy Research Institute, Barcelona (Spain); Iglesias, Ò.; Labarta, A. [Departament de Física Fonamental, Universitat de Barcelona and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain)

    2013-06-15

    We report a study on the pressure response of the anisotropy energy of hollow and solid maghemite nanoparticles. The differences between the maghemite samples are understood in terms of size, magnetic anisotropy and shape of the particles. In particular, the differences between hollow and solid samples are due to the different shape of the nanoparticles and by comparing both pressure responses it is possible to conclude that the shell has a larger pressure response when compared to the core. - Highlights: ► Study of the pressure response of core and shell magnetic anisotropy. ► Contrast between hollow and solid maghemite nanoparticles. ► Disentanglement of nanoparticles core and shell magnetic properties.

  2. Acoustic lens for capacitive micromachined ultrasonic transducers

    Science.gov (United States)

    Chang, Chienliu; Firouzi, Kamyar; Park, Kwan Kyu; Sarioglu, Ali Fatih; Nikoozadeh, Amin; Yoon, Hyo-Seon; Vaithilingam, Srikant; Carver, Thomas; Khuri-Yakub, Butrus T.

    2014-08-01

    Capacitive micromachined ultrasonic transducers (CMUTs) have great potential to compete with traditional piezoelectric transducers in therapeutic ultrasound applications. In this paper we have designed, fabricated and developed an acoustic lens formed on the CMUT to mechanically focus ultrasound. The acoustic lens was designed based on the paraxial theory and made of silicone rubber for acoustic impedance matching and encapsulation. The CMUT was fabricated based on the local oxidation of silicon (LOCOS) and fusion-bonding. The fabricated CMUT was verified to behave like an electromechanical resonator in air and exhibited wideband response with a center frequency of 2.2 MHz in immersion. The fabrication for the acoustic lens contained two consecutive mold castings and directly formed on the surface of the CMUT. Applied with ac burst input voltages at the center frequency, the CMUT with the acoustic lens generated an output pressure of 1.89 MPa (peak-to-peak) at the focal point with an effective focal gain of 3.43 in immersion. Compared to the same CMUT without a lens, the CMUT with the acoustic lens demonstrated the ability to successfully focus ultrasound and provided a viable solution to the miniaturization of the multi-modality forward-looking endoscopes without electrical focusing.

  3. In-the-Spectacle-Lens Telescopic Device

    Science.gov (United States)

    Peli, Eli; Vargas-Martín, Fernando

    2008-01-01

    Spectacle-mounted telescopic systems are prescribed for individuals with visual impairments. Bioptic telescopes are typically mounted toward the top of the spectacle lens (or above the frame) with the telescope eyepiece positioned above the wearer’s pupil. This allows the wearer to use up and down head tilt movements to quickly alternate between the unmagnified wide view (through the carrier lens) and the magnified narrow field-of-view (available through the eyepiece). Rejection of this visual aid has been attributed mainly to its appearance and to the limited field-of-view through the smaller Galilean designs. We designed a wide-field Keplerian telescope that is built completely within the spectacle lens. The design uses embedded mirrors inside the carrier lens for optical pathway folding and conventional lenses or curved mirrors for magnification power. The short height of the ocular, its position, and a small tilt of the ocular mirror enable the wearer to simultaneously view the magnified field above the unmagnified view of the uninterrupted horizontal field. These features improve the cosmetics and utility of the device. The in-the-lens design will allow the telescope to be mass-produced as a commodity ophthalmic lens blank that can be surfaced to include the wearer’s spectacle prescription. PMID:18601572

  4. Conservation through the economics lens.

    Science.gov (United States)

    Farley, Joshua

    2010-01-01

    Although conservation is an inherently transdisciplinary issue, there is much to be gained from examining the problem through an economics lens. Three benefits of such an approach are laid out in this paper. First, many of the drivers of environmental degradation are economic in origin, and the better we understand them, the better we can conserve ecosystems by reducing degradation. Second, economics offers us a when-to-stop rule, which is equivalent to a when-to-conserve rule. All economic production is based on the transformation of raw materials provided by nature. As the economic system grows in physical size, it necessarily displaces and degrades ecosystems. The marginal benefits of economic growth are diminishing, and the marginal costs of ecological degradation are increasing. Conceptually, we should stop economic growth and focus on conservation when the two are equal. Third, economics can help us understand how to efficiently and justly allocate resources toward conservation, and this paper lays out some basic principles for doing so. Unfortunately, the field of economics is dominated by neoclassical economics, which builds an analytical framework based on questionable assumptions and takes an excessively disciplinary and formalistic approach. Conservation is a complex problem, and analysis from individual disciplinary lenses can make important contributions to conservation only when the resulting insights are synthesized into a coherent vision of the whole. Fortunately, there are a number of emerging transdisciplines, such as ecological economics and environmental management, that are dedicated to this task.

  5. Trends in US Contact Lens Prescribing 2002 to 2014.

    Science.gov (United States)

    Efron, Nathan; Nichols, Jason J; Woods, Craig A; Morgan, Philip B

    2015-07-01

    To document contact lens prescribing patterns in the United States between 2002 and 2014. A survey of contact lens prescribing trends was conducted each year between 2002 and 2014, inclusive. Randomly selected contact lens practitioners were asked to provide information relating to 10 consecutive contact lens fits between January and March each year. Over the 13-year survey period, 1650 survey forms were received from US practitioners representing details of 7702 contact lens fits. The mean (±SD) age of lens wearers was 33.6 (±15.2) years, of whom 65.2% were female. Rigid lens new fits decreased from 13.0% in 2002 to 9.4% in 2014. Across this period, silicone hydrogels have replaced mid water contact lens hydrogels as the soft lens material of choice. Toric lenses represented about 25 to 30% of all soft lens fits. Multifocal soft lenses are generally preferred to monovision. Daily disposable lens fits have recently increased, and in 2014, they represented 27.1% of all soft lens fits. Most lenses are prescribed on 1 to 2 weekly or monthly lens replacement regimen. Extended wear remains a minority lens wearing modality. The vast majority of those wearing reusable lenses use multipurpose lens care solutions. Lenses are mostly worn 7 d/wk. This survey has revealed prescribing trends and preferences in the United States over the past 13 years.

  6. Electron spectrometer for gas-phase spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bozek, J.D.; Schlachter, A.S. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    An electron spectrometer for high-resolution spectroscopy of gaseous samples using synchrotron radiation has been designed and constructed. The spectrometer consists of a gas cell, cylindrical electrostatic lens, spherical-sector electron energy analyzer, position-sensitive detector and associated power supplies, electronics and vacuum pumps. Details of the spectrometer design are presented together with some representative spectra.

  7. The Hologenome Concept: Helpful or Hollow?

    Directory of Open Access Journals (Sweden)

    Nancy A Moran

    2015-12-01

    Full Text Available With the increasing appreciation for the crucial roles that microbial symbionts play in the development and fitness of plant and animal hosts, there has been a recent push to interpret evolution through the lens of the "hologenome"--the collective genomic content of a host and its microbiome. But how symbionts evolve and, particularly, whether they undergo natural selection to benefit hosts are complex issues that are associated with several misconceptions about evolutionary processes in host-associated microbial communities. Microorganisms can have intimate, ancient, and/or mutualistic associations with hosts without having undergone natural selection to benefit hosts. Likewise, observing host-specific microbial community composition or greater community similarity among more closely related hosts does not imply that symbionts have coevolved with hosts, let alone that they have evolved for the benefit of the host. Although selection at the level of the symbiotic community, or hologenome, occurs in some cases, it should not be accepted as the null hypothesis for explaining features of host-symbiont associations.

  8. Biomimetic Branched Hollow Fibers Templated by Self-assembled Fibrous Polyvinylpyrrolidone (PVP) Structures in Aqueous Solution

    Science.gov (United States)

    Qiu, Penghe; Mao, Chuanbin

    2010-01-01

    Branched hollow fibers are common in nature, but to form artificial fibers with a similar branched hollow structure is still a challenge. We discovered that polyvinylpyrrolidone (PVP) could self-assemble into branched hollow fibers in an aqueous solution after aging the PVP solution for about two weeks. Based on this finding, we demonstrated two approaches by which the self-assembly of PVP into branched hollow fibers could be exploited to template the formation of branched hollow inorganic fibers. First, inorganic material such as silica with high affinity against the PVP could be deposited on the surface of the branched hollow PVP fibers to form branched hollow silica fibers. To extend the application of PVP self-assembly in templating the formation of hollow branched fibers, we then adopted a second approach where the PVP molecules bound to inorganic nanoparticles (using gold nanoparticles as a model) co-self-assemble with the free PVP molecules in an aqueous solution, resulting in the formation of the branched hollow fibers with the nanoparticles embedded in the PVP matrix constituting the walls of the fibers. Heating the resultant fibers above the glass transition temperature of PVP led to the formation of branched hollow gold fibers. Our work suggests that the self-assembly of the PVP molecules in the solution can serve as a general method for directing the formation of branched hollow inorganic fibers. The branched hollow fibers may find potential applications in microfluidics, artificial blood vessel generation, and tissue engineering. PMID:20158250

  9. Soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2009-01-01

    The formation of solitons upon compression of linearly chirped pulses in hollow-core photonic bandgap fibers is investigated numerically. The dependence of soliton duration on the chirp and power of the input pulse and on the dispersion slope of the fiber is investigated, and the validity...... of an approximate scaling relation is tested. It is concluded that compression of input pulses of several ps duration and sub-MW peak power can lead to a formation of solitons with ∼100 fs duration and multi-megawatt peak powers. The dispersion slope of realistic hollow-core fibers appears to be the main obstacle...

  10. Preparation and Electrochemical Properties of Silver Doped Hollow Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    LI Fu

    2016-11-01

    Full Text Available Silver doped PAN-based hollow carbon nanofibers were prepared combining co-electrospinning with in situ reduction technique subsequently heat treatment to improve the electrochemical performances of carbon based supercapacitor electrodes. The morphology, structure and electrochemical performances of the resulted nanofiber were studied. The results show that the silver nanoparticles can be doped on the surface of hollow carbon nanofibers and the addition of silver favors the improvement of the electrochemical performances, exhibiting the enhanced reversibility of electrode reaction and the capacitance and the reduced charge transfer impedance.

  11. Antiresonant hollow core fiber with seven nested capillaries

    DEFF Research Database (Denmark)

    Antonio-Lopez, Jose E.; Habib, Selim; Van Newkirk, Amy

    2016-01-01

    We report an antiresonant hollow core fiber formed of 7 non-touching capillaries with inner tubes. The fiber has a core diameter of ∼33μm and a core wall of ∼780nm of thickness. We demonstrate robust single mode operation at 1064nm and broad transmission bandwidth.......We report an antiresonant hollow core fiber formed of 7 non-touching capillaries with inner tubes. The fiber has a core diameter of ∼33μm and a core wall of ∼780nm of thickness. We demonstrate robust single mode operation at 1064nm and broad transmission bandwidth....

  12. Hollow-core fibers for high power pulse delivery

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Lyngsø, Jens K.; Jakobsen, Christian

    2016-01-01

    We investigate hollow-core fibers for fiber delivery of high power ultrashort laser pulses. We use numerical techniques to design an anti-resonant hollow-core fiber having one layer of non-touching tubes to determine which structures offer the best optical properties for the delivery of high power......-core fiber. The three fibers are characterized experimentally for the delivery of 22 picosecond pulses at 1032nm. We demonstrate flexible, diffraction limited beam delivery with output average powers in excess of 70W. (C) 2016 Optical Society of America...

  13. Raman lasing in a hollow, bottle-like microresonator

    CERN Document Server

    Ooka, Yuta; Ward, Jonathan; Chromaic, Síle Nic

    2015-01-01

    We report on the fabrication of an ultrahigh quality factor, bottle-like microresonator from a hollow microcapillary, and the realisation of Raman lasing therein at pump wavelengths of $1.55~\\mathrm{\\mu m}$ and $780~\\mathrm{nm}$. Third-order cascaded Raman lasing was observed when pumped at $780~\\mathrm{nm}$. The aerostatic pressure tunability of the Raman laser was also investigated. Thence, we demonstrate that a high dynamic range, high resolution pressure sensor can be realised using the Raman spectrum of the hollow, bottle-like microresonator.

  14. A Comparative Study of Hollow Copper Sulfide Nanoparticles and Hollow Gold Nanospheres on Degradability and Toxicity

    Science.gov (United States)

    Guo, Liangran; Panderi, Irene; Yan, Daisy D.; Szulak, Kevin; Li, Yajuan; Chen, Yi-Tzai; Ma, Hang; Niesen, Daniel B.; Seeram, Navindra; Ahmed, Aftab; Yan, Bingfang; Pantazatos, Dionysios; Lu, Wei

    2013-01-01

    Gold and copper nanoparticles have been widely investigated for photothermal therapy of cancer. However, degradability and toxicity of these nanoparticles remain concerns. Here, we compare hollow CuS nanoparticles (HCuSNPs) with hollow gold nanospheres (HAuNS) in similar particle sizes and morphology following intravenous administration to mice. The injected pegylated HCuSNPs (PEG-HCuSNPs) are eliminated through both hepatobiliary (67 percentage of injected dose, %ID) and renal (23 %ID) excretion within one month post injection. By contrast, 3.98 %ID of Au is excreted from liver and kidney within one month after i.v. injection of pegylated HAuNS (PEG-HAuNS). Comparatively, PEG-HAuNS are almost non-metabolizable, while PEG-HCuSNPs are considered biodegradable nanoparticles. PEG-HCuSNPs do not show significant toxicity by histological or blood chemistry analysis. Principal component analysis and 2-D peak distribution plots of data from matrix-assisted laser desorption ionization-time of flight imaging mass spectrometry (MALDI-TOF IMS) of liver tissues demonstrated a reversible change in the proteomic profile in mice receiving PEG-HCuSNPs. This is attributed to slow dissociation of Cu ion from CuS nanoparticles along with effective Cu elimination for maintaining homeostasis. Nonetheless, an irreversible change in the proteomic profile is observed in the liver from mice receiving PEG-HAuNS by analysis of MALDI-TOF IMS data, probably due to the non-metabolizability of Au. This finding correlates with the elevated serum lactate dehydrogenase at 3 months after PEG-HAuNS injection, indicating potential long-term toxicity. The comparative results between the two types of nanoparticles will advance the development of HCuSNPs as a new class of biodegradable inorganic nanomaterials for photothermal therapy. PMID:24053214

  15. Synthesis and NIR optical properties of hollow gold nanospheres with LSPR greater than one micrometer

    Science.gov (United States)

    Xie, Hai-Nan; Larmour, Iain A.; Chen, Yi-Chieh; Wark, Alastair W.; Tileli, Vasiliki; McComb, David W.; Faulds, Karen; Graham, Duncan

    2012-12-01

    observed from hollow gold with a LSPR of 650 nm and a weaker, yet observable, signal from HGNs with a LSPR of 775 nm. However, no obvious signals were observed in the case of standard citrate reduced gold, silver or HGNs with a LSPR of 1080 nm. The absorption properties of HGNs were investigated by monitoring their photothermal activity. In this case, different nanoparticle suspensions including citrate reduced gold, silver, and HGNs were illuminated by a continuous laser at 785 nm excitation wavelength and the absorption efficiency of HGNs with a LSPR of 775 nm was calculated to be 0.81% which is more than 5 times higher than the absorption efficiency of citrate reduced gold nanoparticles under similar conditions. Electronic supplementary information (ESI) available: See DOI: 10.1039/c2nr33187j

  16. Surface modification of fluorosilicone acrylate RGP contact lens via low-temperature argon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yin Shiheng [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Analytical and Testing Center, South China University of Technology, Guangzhou 510640 (China); Wang Yingjun [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Ren Li [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)], E-mail: psliren@scut.edu.cn; Zhao Lianna [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Kuang Tongchun [Analytical and Testing Center, South China University of Technology, Guangzhou 510640 (China); Chen Hao [Wenzhou Medical College, Wenzhou 325035 (China)], E-mail: chenhao823@mail.wz.zj.cn; Qu Jia [Wenzhou Medical College, Wenzhou 325035 (China)

    2008-11-15

    A fluorosilicone acrylate rigid gas permeable (RGP) contact lens was modified via argon plasma to improve surface hydrophilicity and resistance to protein deposition. The influence of plasma treatment on surface chemical structure, hydrophilicity and morphology of RGP lens was investigated by X-ray photoelectron spectrometer (XPS), contact angle measurements and scanning electron microscope (SEM), respectively. The contact angle results showed that the hydrophilicity of the contact lens was improved after plasma treatment. XPS results indicated that the incorporation of oxygen-containing groups on surface and the transformation of silicone into hydrophilic silicate after plasma treatment are the main reasons for the surface hydrophilicity improvement. SEM results showed that argon plasma with higher power could lead to surface etching.

  17. Liposome preparation using a hollow fiber membrane contactor--application to spironolactone encapsulation.

    Science.gov (United States)

    Laouini, A; Jaafar-Maalej, C; Sfar, S; Charcosset, C; Fessi, H

    2011-08-30

    In this study, we present a novel liposome preparation technique suitable for the entrapment of pharmaceutical and cosmetic agents. This new method uses a membrane contactor in a hollow fiber configuration. In order to investigate the process, key parameters influence on the liposome characteristics was studied. It has been established that the vesicle size distribution decreased with the organic phase pressure decrease, the phospholipid concentration decreases and the aqueous to organic phase volume ratio increases. Liposomes were filled with a hydrophobic drug model, spironolactone that could be used for a paediatric medication. The mean size of drug-free and drug-loaded liposomes was, respectively, 113 ± 4 nm and 123 ± 3 nm. The zeta potential of drug-free and drug-loaded liposomes was, respectively, -43 ± 0.7 mV and -23 ± 0.6 mV. High entrapment efficiency values were successfully achieved (93 ± 1.12%). Transmission electron microscopy images revealed nanometric sized and spherical shaped oligo-lamellar vesicles. The release profile showed a rapid and complete release within about 5h. Additionally, special attention was paid on process reproducibility and long term lipid vesicles stability. Results confirmed the robustness of the hollow fiber module based technique. Moreover, the technique is simple, fast and has a potential for continuous production of nanosized liposome suspensions at large scale. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. High-Temperature Performance and Multiscale Damage Mechanisms of Hollow Cellulose Fiber-Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Liping Guo

    2016-01-01

    Full Text Available Spalling resistance properties and their damage mechanisms under high temperatures are studied in hollow cellulose fiber-reinforced concrete (CFRC used in tunnel structures. Measurements of mass loss, relative dynamic elastic modulus, compressive strength, and splitting tensile strength of CFRC held under high temperatures (300, 600, 800, and 1050°C for periods of 2.5, 4, and 5.5 h were carried out. The damage mechanism was analyzed using scanning electron microscopy, mercury intrusion porosimetry, thermal analysis, and X-ray diffraction phase analysis. The results demonstrate that cellulose fiber can reduce the performance loss of concrete at high temperatures; the effect of holding time on the performance is more noticeable below 600°C. After exposure to high temperatures, the performance of ordinary concrete deteriorates faster and spalls at 700–800°C; in contrast, cellulose fiber melts at a higher temperature, leaving a series of channels in the matrix that facilitate the release of the steam pressure inside the CFRC. Hollow cellulose fibers can thereby slow the damage caused by internal stress and improve the spalling resistance of concrete under high temperatures.

  19. Mesoporous hollow carbon spheres for lithium–sulfur batteries: distribution of sulfur and electrochemical performance

    Directory of Open Access Journals (Sweden)

    Anika C. Juhl

    2016-08-01

    Full Text Available Hollow carbon spheres (HCS with a nanoporous shell are promising for the use in lithium–sulfur batteries because of the large internal void offering space for sulfur and polysulfide storage and confinement. However, there is an ongoing discussion whether the cavity is accessible for sulfur. Yet no valid proof of cavity filling has been presented, mostly due to application of unsuitable high-vacuum methods for the analysis of sulfur distribution. Here we describe the distribution of sulfur in hollow carbon spheres by powder X-ray diffraction and Raman spectroscopy along with results from scanning electron microscopy and nitrogen physisorption. The results of these methods lead to the conclusion that the cavity is not accessible for sulfur infiltration. Nevertheless, HCS/sulfur composite cathodes with areal sulfur loadings of 2.0 mg·cm−2 were investigated electrochemically, showing stable cycling performance with specific capacities of about 500 mAh·g−1 based on the mass of sulfur over 500 cycles.

  20. Fine-tunable plasma nano-machining for fabrication of 3D hollow nanostructures: SERS application

    Science.gov (United States)

    Mehrvar, L.; Hajihoseini, H.; Mahmoodi, H.; Tavassoli, S. H.; Fathipour, M.; Mohseni, S. M.

    2017-08-01

    Novel processing sequences for the fabrication of artificial nanostructures are in high demand for various applications. In this paper, we report on a fine-tunable nano-machining technique for the fabrication of 3D hollow nanostructures. This technique originates from redeposition effects occurring during Ar dry etching of nano-patterns. Different geometries of honeycomb, double ring, nanotube, cone and crescent arrays have been successfully fabricated from various metals such as Au, Ag, Pt and Ti. The geometrical parameters of the 3D hollow nanostructures can be straightforwardly controlled by tuning the discharge plasma pressure and power. The structure and morphology of nanostructures are probed using atomic force microscopy (AFM), scanning electron microscopy (SEM), optical emission spectroscopy (OES) and energy dispersive x-ray spectroscopy (EDS). Finally, a Ag nanotube array was assayed for application in surface enhanced Raman spectroscopy (SERS), resulting in an enhancement factor (EF) of 5.5 × 105, as an experimental validity proof consistent with the presented simulation framework. Furthermore, it was found that the theoretical EF value for the honeycomb array is in the order of 107, a hundred times greater than that found in nanotube array.

  1. Synthesis of Hollow Silver Spheres using Spherical Vaterite-type Calcium Carbonate as Template

    Energy Technology Data Exchange (ETDEWEB)

    Park, Minyoung; Go, Hani; Kim, Jae-Hyun; Rhee, Seog Woo [Kongju National University, Kongju (Korea, Republic of)

    2016-03-15

    In this work, we describe the synthesis of hollow silver spheres using vaterite-type CaCO{sub 3} as template. The spherical vaterite-type CaCO{sub 3} was selectively precipitated d reaction of aqueous CaCl{sub 2} and Na{sub 2}CO{sub 3} in the presence of the polyelectrolyte poly(4-styrenesulfonate). Aqueous AgNO{sub 3} solution containing NH{sub 2}-functionalized CaCO{sub 3} particles was treated with reducing agents such as ascorbic acid, NaBH{sub 4}, and acetaldehyde, and the reduced silver particles were deposited on the surface of CaCO{sub 3}particles to form uniform silvershells. The CaCO{sub 3} used as template was removed from the CaCO{sub 3}/Ag composite by treatment with acid. Finally, the hollow silver sphere was obtained. The morphologies of product were investigated using electron microscopy, the chemical composition of the composite was analyzed using energy-dispersive X-ray spectroscopy, the vibration modes of the carbonate ion were investigated by Fourier transform infrared spectroscopy, the thermal mass change was measured using the thermogravimetric analysis, and the solid phases were confirmed by powder X-ray diffraction.

  2. Turnable Semiconductor Laser Spectroscopy in Hollow Optical Waveguides, Phase II SBIR

    Energy Technology Data Exchange (ETDEWEB)

    Gregory J. Fetzer, Ph.D.

    2001-12-24

    In this study a novel optical trace gas sensor based on a perforated hollow waveguide (PHW) was proposed. The sensor has been given the acronym ESHOW for Environmental Sensor using Hollow Optical Waveguides. Realizations of the sensor have demonstrated rapid response time (<2s), low minimum detection limits (typically around 3 x 10-5 absorbance). Operation of the PHW technology has been demonstrated in the near-infrared (NIR) and mid0infrared (MIR) regions of the spectrum. Simulation of sensor performance provided in depth understanding of the signals and signal processing required to provide high sensitivity yet retain rapid response to gas changes. A dedicated sensor electronics and software foundation were developed during the course of the Phase II effort. Commercial applications of the sensor are ambient air and continuous emissions monitoring, industrial process control and hazardous waste site monitoring. There are numerous other applications for such a sensor including medical diagnosis and treatment, breath analysis for legal purposes, water quality assessment, combustion diagnostics, and chemical process control. The successful completion of Phase II resulted in additional funding of instrument development by the Nations Institute of Heath through a Phase I SBIR grant and a strategic teaming relationship with a commercial manufacture of medical instrumentation. The purpose of the NIH grant and teaming relationship is to further develop the sensor to monitor NO in exhaled breath for the purposes of asthma diagnosis.

  3. Enhancing the Electrocatalytic Property of Hollow Structured Platinum Nanoparticles for Methanol Oxidation Through A Hybrid Construction

    Science.gov (United States)

    Feng, Yan; Liu, Hui; Wang, Pengfei; Ye, Feng; Tan, Qiangqiang; Yang, Jun

    2014-08-01

    The integration of different components into a hybrid nanosystem for the utilization of the synergistic effects is an effective way to design the electrocatalysts. Herein, we demonstrate a hybrid strategy to enhance the electrocatalytic property of hollow structured Pt nanoparticles for methanol oxidation reaction. This strategy begins with the preparation of bimetallic Ag-Pt nanoparticles with a core-shell construction. Element sulfur is then added to transform the core-shell Ag-Pt nanostructures into hybrid nanodimers consisting of Ag2S nanocrystals and remaining Pt domains with intact hollow interiors (Ag2S-hPt). Finally, Au is deposited at the surface of the Ag2S domain in each hetero-dimer, resulting in the formation of ternary Ag2S-Au-hPt nanocomposites with solid-state interfaces. The ternary nanocomposites exhibit enhanced electrocatalytic property toward methanol oxidation due to the strong electronic coupling between Pt and other domains in the hybrid particles. The concept might be used toward the design and synthesis of other hetero-nanostructures with technological importance.

  4. Fine-tunable plasma nano-machining for fabrication of 3D hollow nanostructures: SERS application.

    Science.gov (United States)

    Mehrvar, L; Hajihoseini, H; Mahmoodi, H; Tavassoli, S H; Fathipour, M; Mohseni, S M

    2017-08-04

    Novel processing sequences for the fabrication of artificial nanostructures are in high demand for various applications. In this paper, we report on a fine-tunable nano-machining technique for the fabrication of 3D hollow nanostructures. This technique originates from redeposition effects occurring during Ar dry etching of nano-patterns. Different geometries of honeycomb, double ring, nanotube, cone and crescent arrays have been successfully fabricated from various metals such as Au, Ag, Pt and Ti. The geometrical parameters of the 3D hollow nanostructures can be straightforwardly controlled by tuning the discharge plasma pressure and power. The structure and morphology of nanostructures are probed using atomic force microscopy (AFM), scanning electron microscopy (SEM), optical emission spectroscopy (OES) and energy dispersive x-ray spectroscopy (EDS). Finally, a Ag nanotube array was assayed for application in surface enhanced Raman spectroscopy (SERS), resulting in an enhancement factor (EF) of 5.5 × 10 5 , as an experimental validity proof consistent with the presented simulation framework. Furthermore, it was found that the theoretical EF value for the honeycomb array is in the order of 10 7 , a hundred times greater than that found in nanotube array.

  5. Density functional studies on the hollow resonances in Li-isoelectronic sequence (Z=4--10

    CERN Document Server

    Roy, Amlan K

    2013-01-01

    In this sequel to our work on triply excited hollow resonances in three-electron atomic systems, a density functional theory (DFT)-based formalism is employed to investigate similar resonances in Li-isoelectronic series (Z=4--10). A combination of the work-function-based local nonvariational exchange potential and the popular gradient plus Laplacian included Lee-Yang-Parr correlation energy functional is used. First, all the 8 n=2 intrashell states of B$^{2+}$, N$^{4+}$ and F$^{6+}$ are presented, which are relatively less studied in the literature compared to the remaining 4 members. Then calculations are performed for the 8 $2l2l'$n$l"$ (3$\\leq$n$\\leq$6) hollow resonance series; {\\em viz.,} 2s$^2$ns $^2$S$^e$, 2s$^2$np $^2$P$^o$, 2s$^2$nd $^2$D$^e$, 2s2pns $^4$P$^o$, 2s2pnp $^4$D$^e$, 2p$^2$ns $^4$P$^e$, 2p$^2$np $^4$D$^o$ and 2p$^2$ns $^2$D$^e$, of all the 7 positive ions. Next, as an illustration, higher resonance positions of the 2s$^2$ns $^2$S$^e$ series are calculated for all the ions with a maximum of...

  6. Risk factors for contact lens-induced papillary conjunctivitis associated with silicone hydrogel contact lens wear.

    Science.gov (United States)

    Tagliaferri, Angela; Love, Thomas E; Szczotka-Flynn, Loretta B

    2014-05-01

    Contact lens-induced papillary conjunctivitis (CLPC) continues to be a major cause of dropout during extended wear of contact lenses. This retrospective study explores risk factors for the development of CLPC during extended wear of silicone hydrogel lenses. Data from 205 subjects enrolled in the Longitudinal Analysis of Silicone Hydrogel Contact Lens study wearing lotrafilcon A silicone hydrogel lenses for up to 30 days of continuous wear were used to determine risk factors for CLPC in this secondary analysis of the main cohort. The main covariates of interest included substantial lens-associated bacterial bioburden and topographically determined lens base curve-to-cornea fitting relationships. Additional covariates of interest included history of adverse events, time of year, race, education level, gender, and other subject demographics. Statistical analyses included univariate logistic regression to assess the impact of potential risk factors on the binary CLPC outcome and Cox proportional hazards regression to describe the impact of those factors on time-to-CLPC diagnosis. Across 12 months of follow-up, 52 subjects (25%) experienced CLPC. No associations were found between the CLPC development and the presence of bacterial bioburden, lens-to-cornea fitting relationships, history of adverse events, gender, or race. Contact lens-induced papillary conjunctivitis development followed the same seasonal trends as the local peaks in environmental allergens. Lens fit and biodeposits, in the form of lens-associated bacterial bioburden, were not associated with the development of CLPC during extended wear with lotrafilcon A silicone hydrogel lenses.

  7. Recurrence rates of herpes simplex virus keratitis in contact lens and non-contact lens wearers.

    Science.gov (United States)

    Mucci, Joti Juneja; Utz, Virginia M; Galor, Anat; Feuer, William; Jeng, Bennie H

    2009-07-01

    To evaluate the recurrence rates of herpes simplex virus (HSV) keratitis in contact lens wearers compared with non-contact lens wearers. Retrospective cohort study. Charts of patients diagnosed with HSV keratitis seen at the Cleveland Clinic between January 2001 and December 2004 were reviewed. One hundred seventeen patients were included in this study: 21 contact lens wearers and 96 non-contact lens wearers. Contact lens wearers were found to have a higher median recurrence rate (0.4 episodes/year) compared with non-contact lens wearers (0.2 episodes/year) (P=0.02). A multivariate regression evaluating factors predictive of the number of recurrences found that contact lens use remained a significant predictive variable (P=0.02) when accounting for patient demographic and disease factors and variable follow-up time. Patients with a history of HSV keratitis should be counseled about the potential increased risk of recurrence that may be associated with contact lens wear.

  8. The Sloan Lens ACS Survey. V. The full ACS strong-lens sample

    NARCIS (Netherlands)

    Bolton, Adam S.; Burles, Scott; Koopmans, Leon V. E.; Treu, Tommaso; Gavazzi, Raphael; Moustakas, Leonidas A.; Wayth, Randall; Schlegel, David J.

    2008-01-01

    We present the definitive data for the full sample of 131 strong gravitational lens candidates observed with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope by the Sloan Lens ACS (SLACS) Survey. All targets were selected for higher redshift emission lines and lower redshift

  9. Parallels between neuron and lens fiber cell structure and molecular regulatory networks.

    Science.gov (United States)

    Frederikse, Peter H; Kasinathan, Chinnaswamy; Kleiman, Norman J

    2012-08-15

    Studies over the past fifty years have identified extensive similarities between neurons and elongated fiber cells that make up in the interior of the ocular lens. Electron micrographs showed parallels in the organization of their intracellular vesicle transport machinery and between lens fiber cell lateral protrusions and dendritic spines. Consistent with those observations, a number of gene products first characterized as highly neuron-preferred in their expression were also demonstrated in lens fiber cells. Going further, a fundamental network of regulatory factors with critical roles in determining the neuronal phenotype were also identified in lenses, and showed a corresponding mutually exclusive distribution of neural and non-neural factor isoforms in mitotic lens epithelial cells and post-mitotic fiber cells consistent with their interlocking functions in neural cells. These included REST/NRSF transcription factors, members of major RNA binding protein families, and "brain-specific" miRNAs that were each shown to have global roles in governing neural and non-neural gene expression and alternative transcript splicing in vertebrates. This review discusses these extensive parallels between neurons and fiber cells and implications regarding common themes in lens and neural cell physiology and disease, which may also suggest related evolutionary processes. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Study on the surface of fluorosilicone acrylate RGP contact lens treated by low-temperature nitrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ren Li [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)], E-mail: psliren@scut.edu.cn; Yin Shiheng [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Analytical and Testing Center, South China University of Technology, Guangzhou 510640 (China); Zhao Lianna; Wang Yingjun [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Chen Hao [Wenzhou Medical College, Wenzhou 325035 (China); Qu Jia [Wenzhou Medical College, Wenzhou 325035 (China)], E-mail: jqu@wzmc.net

    2008-11-15

    In order to improve the surface hydrophilicity of fluorosilicone acrylate rigid gas permeable (RGP) contact lens, low temperature nitrogen plasma was used to modify the lens surface. Effects of plasma conditions on the surface structures and properties were investigated. Results indicated that the surface hydrophilicity of RGP contact lens was significantly improved after treatment. X-ray photoelectron spectroscopy (XPS) results showed that the nitrogen element was successfully incorporated into the surface. Furthermore, some new bonds such as N-C=O, F{sup -} and silicate were formed on the lens surface after nitrogen plasma treatment, which could result in the improvement of the surface hydrophilicity. Scanning electronic microscope (SEM) results indicated that nitrogen plasma with moderate power could make the surface smoother in some degree, while plasma with higher power could etch the surface.

  11. Mechanical Properties of Contact Lens Materials.

    Science.gov (United States)

    Kim, Eon; Saha, Mou; Ehrmann, Klaus

    2017-11-07

    To evaluate the mechanical properties of commonly available soft contact lens materials and compare results using custom-built MicroTensometer. The Young modulus, parameters for stress relaxation, and toughness of 18 types of single vision soft contact lenses were measured using custom-built MicroTensometer. Five lenses of each type were soaked in standard phosphate buffered saline and measured at a temperature of 35°C. Each lens was flattened and sliced into a rectangular strip sample using two parallel blades. The Acuvue Moist 1-Day and SofLens Daily lenses measured lowest moduli, whereas Air Optix Night & Day Aqua and Premio measured the highest. The measured moduli for silicone hydrogel materials were generally higher compared with the hydrogels except for Dailies AquaComfort Plus. The exponential curve fitted over the decay in stress showed a consistent time constant of approximately 10 sec for most lens types measured. However, the amplitude constant varied from 2.84% for SofLens Daily to 22.39% for Acuvue TruEye 1-Day. The toughness results showed that Dailies AquaComfort Plus is strong but not necessarily tough. The mechanical properties of commonly prescribed soft contact lens materials were measured using a dedicated instrument. Its reliability was demonstrated, and modulus results were compared against published data from manufacturers and other research groups. Agreement was generally good, with only a few exceptions exceeding 15% difference. The more recently released silicone hydrogel lens types have reduced modulus, approaching that of medium or high water content hydrogel materials.

  12. Acanthamoeba keratitis and contact lens wear.

    Science.gov (United States)

    Lindsay, Richard G; Watters, Grant; Johnson, Richard; Ormonde, Susan E; Snibson, Grant R

    2007-09-01

    Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens-related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three-year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.

  13. Corneal topography and soft contact lens fit.

    Science.gov (United States)

    Young, Graeme; Schnider, Cristina; Hunt, Chris; Efron, Suzanne

    2010-05-01

    To determine which ocular topography variables affect soft contact lens fit. Fifty subjects each wore three pairs of soft lenses in random succession (Vistakon Acuvue 2, Vistakon Acuvue Advance, Ciba Vision Night & Day), and various aspects of lens fit were evaluated. The steeper base curves of each type were worn in one eye and the flatter base curves in the other eye. Corneal topography data were collected using a Medmont E300 corneal topographer (Camberwell, Australia). Corneal curvature, shape factor (SF), and corneal height were measured over a 10 mm chord and also over the maximum measurable diameter. These were measured in the horizontal, vertical, steepest, and flattest meridians. With each lens type, the steeper base curve provided the best fit on the greatest proportion of eyes and the significant differences in various aspects of fit were noted between base curves. For each lens type, there was no significant difference in mean K-reading between those eyes best fit with the steeper base curve and those eyes best fit with the flatter base curve. Two of the lenses showed a positive correlation between centration and horizontal corneal height (maximum), whereas one lens showed a negative correlation between centration and horizontal SF (SF = e). Several lenses showed a positive correlation between post-blink movement and horizontal or vertical corneal SF. The measurement of corneal topography using current Placido disc instrumentation allows a better prediction of soft lens fit than by keratometry, but it is not reliable enough to enable accurate selection of the best fitting base curve. Some correlations are evident between corneal measurements; however, trial fitting remains the method of choice for selection of soft lens base curve.

  14. Hierarchical paramecium-like hollow and solid Au/Pt bimetallic nanostructures constructed using goethite as template

    Energy Technology Data Exchange (ETDEWEB)

    Liu Wei; Repo, Eveliina; Sillanpaeae, Mika [Laboratory of Applied Environmental Chemistry, University of Eastern Finland, Patteristonkatu 1, FI-50100 Mikkeli (Finland); Heikkilae, Mikko; Leskelae, Markku, E-mail: weiliuzk@yahoo.cn, E-mail: mika.sillanpaa@uef.fi [Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, PO Box 55 (A.I. Virtasen aukio 1), FI-00014, Helsinki (Finland)

    2010-10-01

    Novel hollow and solid paramecium-like hierarchical Au/Pt bimetallic nanostructures were constructed using goethite as template via a seed-mediated growth method. Transmission electron microscopy (TEM), {xi}-potential measurement, UV-vis spectroscopy, energy dispersive x-ray spectroscopy (EDS), ICP-AES measurement, x-ray powder diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were utilized to systematically characterize the bimetallic nanostructures. It is found that the core structure of the paramecium-like bimetallic nanomaterial is closely related to reducing agent. When ascorbic acid is used as reducing agent, goethite serves as in situ sacrificed template and hollow paramecium-like bimetallic structure is obtained. When NH{sub 2}OH{center_dot}HCl is used, solid nanostructure with preserved goethite core is produced. Heating the reaction solution is necessary to obtain the paramecium-like morphology with rough interconnected Pt cilia shell. The thickness of Pt cilia layer can be controlled by adjusting the molar ratio of H{sub 2}PtCl{sub 6} to Au nanoseeds. The overgrowth of the rough Pt cilia is proposed to be via an autocatalytic and three-dimensional heterogeneous nucleation process first through flower-like morphology. Both the hollow and solid hierarchical paramecium-like Au/Pt bimetallic nanostructures show good catalytic activities.

  15. Hollow carbon nanospheres/silicon/alumina core-shell film as an anode for lithium-ion batteries

    Science.gov (United States)

    Li, Bing; Yao, Fei; Bae, Jung Jun; Chang, Jian; Zamfir, Mihai Robert; Le, Duc Toan; Pham, Duy Tho; Yue, Hongyan; Lee, Young Hee

    2015-01-01

    Hollow carbon nanospheres/silicon/alumina (CNS/Si/Al2O3) core-shell films obtained by the deposition of Si and Al2O3 on hollow CNS interconnected films are used as the anode materials for lithium-ion batteries. The hollow CNS film acts as a three dimensional conductive substrate and provides void space for silicon volume expansion during electrochemical cycling. The Al2O3 thin layer is beneficial to the reduction of solid-electrolyte interphase (SEI) formation. Moreover, as-designed structure holds the robust surface-to-surface contact between Si and CNSs, which facilitates the fast electron transport. As a consequence, the electrode exhibits high specific capacity and remarkable capacity retention simultaneously: 1560 mA h g−1 after 100 cycles at a current density of 1 A g−1 with the capacity retention of 85% and an average decay rate of 0.16% per cycle. The superior battery properties are further confirmed by cyclic voltammetry (CV) and impedance measurement. PMID:25564245

  16. Synthesis of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres via homogeneous precipitation route

    Directory of Open Access Journals (Sweden)

    Peng-Fei Ai, Ying-Liang Liu, Li-Yuan Xiao, Hou-Jin Wang and Jian-Xin Meng

    2010-01-01

    Full Text Available A phosphorescent material in the form of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres was prepared by homogeneous precipitation using monodispersed carbon spheres as hard templates. Y2O3:Eu3+ hollow microspheres were first synthesized to serve as the precursor. Y2O2S:Eu3+, Mg2+, Ti4+ powders were obtained by calcinating the precursor in a CS2 atmosphere. The crystal structure, morphology and optical properties of the composites were characterized. X-ray diffraction measurements confirmed the purity of the Y2O2S phase. Electron microscopy observations revealed that the Y2O2S:Eu3+, Mg2+, Ti4+ particles inherited the hollow spherical shape from the precursor after being calcined in a CS2 atmosphere and that they had a diameter of 350–450 nm and a wall thickness of about 50–80 nm. After ultraviolet radiation at 265 or 325 nm for 5 min, the particles emitted strong red long-lifetime phosphorescence originating from Eu3+ ions. This phosphorescence is associated with the trapping of charge carriers by Ti4+ and Mg2+ ions.

  17. Hollow and yolk-shell iron oxide nanostructures on few-layer graphene in Li-ion batteries.

    Science.gov (United States)

    Sun, Zhenyu; Xie, Kunpeng; Li, Zi An; Sinev, Ilja; Ebbinghaus, Petra; Erbe, Andreas; Farle, Michael; Schuhmann, Wolfgang; Muhler, Martin; Ventosa, Edgar

    2014-02-10

    We report a simple and template-free strategy for the synthesis of hollow and yolk-shell iron oxide (FeOx) nanostructures sandwiched between few-layer graphene (FLG) sheets. The morphology and microstructure of this material are characterized in detail by X-ray diffraction, X-ray absorption near-edge structure, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning and transmission electron microscopy. Its properties are evaluated as negative electrode material for Li-ion batteries and compared with those of solid FeOx/FLG and two commercial iron oxides. In all cases, the content of carbon in the electrode has a great influence on the performance. The use of pristine FLG improves the capacity retention and further enhancement is achieved with the hollow structure. For a low carbon loading of 18 wt. %, the presence of metallic iron in the hollow and yolk-shell FeOx/FLG composite significantly enhances the capacity retention, albeit with a relatively lower initial reversible capacity, retaining above 97% after 120 cycles at 1000 mA g(-1) in the voltage range of 0.1-3.0 V. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. A nitric oxide releasing self-assembled peptide amphiphile nanomatrix for improving the biocompatibility of microporous hollow fibers

    Science.gov (United States)

    El-Ferzli, George T; Andukuri, Adinarayana; Alexander, Grant; Scopel, Michaella; Ambalavanan, Namasivayam; Patel, Rakesh P; Jun, Ho-Wook

    2015-01-01

    Oxygenators are critical components of extracorporeal circuits used frequently in cardiopulmonary bypass and intensive care, but platelet activation and induction of a complex inflammatory response are usually observed with their use. To improve the biocompatibility of oxygenators, we developed a nitric oxide (NO)-releasing, self-assembled peptide amphiphile nanomatrix. The nanomatrix formed a homogenous coating over the microporous hollow fibers as demonstrated by scanning electron microscopy. We quantitated platelet adhesion to the artificial fibers by measuring absorbance/area of platelets (Abs/A; nm/m2) using acid phosphatase assay. There was a 17-fold decrease in platelet adhesion to the nanomatrix (Abs/A = 0.125) compared to collagen controls (Abs/A = 2.07; p0.05) in a bench top test circuit at different flow rates as estimated by change in partial pressure of oxygen in relation to water velocity through fibers. These findings demonstrate the feasibility of coating microporous hollow fibers with a NO-releasing, self-assembled amphiphile nanomatrix that may improve the biocompatibility of the hollow fibers without affecting their gas exchange capacity. PMID:26102178

  19. Housing shortages in urban regions: aggressive interactions at tree hollows in forest remnants.

    Directory of Open Access Journals (Sweden)

    Adrian Davis

    Full Text Available Urbanisation typically results in a reduction of hollow-bearing trees and an increase in the density of particularly species, potentially resulting in an increased level of competition as cavity-nesting species compete for a limited resource. To improve understanding of hollow usage between urban cavity-nesting species in Australia, particularly parrots, we investigated how the hollow-using assemblage, visitation rate, diversity and number of interactions varied between hollows within urban remnant forest and continuous forest. Motion-activated video cameras were installed, via roped access to the canopy, and hollow usage was monitored at 61 hollows over a two-year period. Tree hollows within urban remnants had a significantly different assemblage of visitors to those in continuous forest as well as a higher rate of visitation than hollows within continuous forest, with the rainbow lorikeet making significantly more visitations than any other taxa. Hollows within urban remnants were characterised by significantly higher usage rates and significantly more aggressive interactions than hollows within continuous forest, with parrots responsible for almost all interactions. Within urban remnants, high rates of hollow visitation and both interspecific and intraspecific interactions observed at tree hollows suggest the number of available optimal hollows may be limiting. Understanding the usage of urban remnant hollows by wildlife, as well as the role of parrots as a potential flagship for the conservation of tree-hollows, is vital to prevent a decrease in the diversity of urban fauna, particularly as other less competitive species risk being outcompeted by abundant native species.

  20. Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision

    Directory of Open Access Journals (Sweden)

    Ladan Espandar

    2011-01-01

    Full Text Available Ladan Espandar1, Shameema Sikder2, Majid Moshirfar31Department of Ophthalmology, Tulane University, New Orleans, LA, USA; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA; 3John A Moran Eye Center, University of Utah, Salt Lake City, UT, USAAbstract: Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL. The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed.Keywords: hydrophilic acrylic intraocular lens, Softec HD intraocular lens, aspheric intraocular lens, IOL

  1. Lentil (Lens culinaris) lipid transfer protein Len c 3: a novel legume allergen.

    Science.gov (United States)

    Akkerdaas, J; Finkina, E I; Balandin, S V; Santos Magadán, S; Knulst, A; Fernandez-Rivas, M; Asero, R; van Ree, R; Ovchinnikova, T V

    2012-01-01

    Lentils are increasingly consumed in many parts of the world.Two allergens, Len c 1 and 2, have been reported previously. Recently, peanut and green bean lipid transfer proteins (LTPs) have been identified as the first two members of an important group of allergens that might be associated with severe food allergies. To investigate lentil LTP as a potential new allergen. Efficacy of LTP extraction was monitored at different acidic pH values, using immunoblotting with cross-reactive anti-peach LTP antiserum. Natural LTP was purified from lentil extract and expressed as recombinant allergen in Escherichia coli. Sera from 10 lentil-allergic and/or -sensitized patients (Spain: 6, Italy: 1 and the Netherlands: 3) were used to further characterize lentil LTP. Natural lentil LTP, purified from the homogenized germinated seeds and optimally extracted at pH 3, was identified and designated as allergen Len c 3. By CAP, 9/10 sera showed specific IgE to Len c 3. Recombinant (r) Len c 3 was successfully purified. The natural (n) Len c 3 CAP was completely inhibited by rLen c 3/rPru p 3. IgE binding to lentil pH 3 extract blot was completely inhibited by rLen c 3. The availability of immunochemically active nLen/rLen c 3 as a novel legume allergen facilitates further development and implementation of a third (next to peanut and green bean) legume LTP in component-resolved diagnosis strategies and contributes to evaluate the clinical importance of legume LTPs. Preferential extraction of Len c 3 (pH 3) will affect the production of sensitive extract-based diagnostic tests. Copyright © 2011 S. Karger AG, Basel.

  2. Iron oxide nanoparticle layer templated by polydopamine spheres: a novel scaffold toward hollow-mesoporous magnetic nanoreactors

    Science.gov (United States)

    Huang, Liang; Ao, Lijiao; Xie, Xiaobin; Gao, Guanhui; Foda, Mohamed F.; Su, Wu

    2014-12-01

    Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m2 g-1). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi-functionality.Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m2 g-1). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi

  3. Hierarchically structured ZnO-graphene hollow microspheres towards effective reusable adsorbent for organic pollutant via photodegradation process

    Energy Technology Data Exchange (ETDEWEB)

    Bera, Susanta; Pal, Moumita; Naskar, Atanu; Jana, Sunirmal, E-mail: sjana@cgcri.res.in

    2016-06-05

    Present work reports on successful synthesis of hierarchical hollow microspheres (HHM) from ZnO-chemically converted graphene (CCG) nanocomposites by adopting low-temperature surfactant/template free solution method, varying graphene oxide (GO) to zinc acetate dihydrate weight ratio (R = 0.00, 0.01, 0.032, 0.063) in the precursors. It is found that the HHM consist of self-assembled ZnO nanoparticles, chemically interacted with CCG as evidenced from structural characterizations (X-ray diffraction, field emission scanning and transmission electron microscopes) with UV–Vis, FTIR, Raman and X-ray photoelectron spectroscopies. Multipoint BET nitrogen adsorption–desorption isotherms of ZG30, synthesized using an optimum GO content (R = 0.032) showed relatively high specific surface area. The sample showed significantly improved adsorption capacity of rhodamine B dye (as water pollutant) compare to pristine ZnO (R = 0.0) as well as commercially available P25 (TiO{sub 2}). The ZG30 functioned as reusable adsorbent due to its highly efficient photocatalytic activity under UV (λ, 254 nm) irradiation. Methyl orange and phenol were also used to check the effectiveness of ZG30 for permanent cleaning of the pollutants. This facile process could create an avenue for synthesis of hollow microspheres from different metal oxide semiconductor–graphene nanocomposites for efficient and reusable adsorbent of water soluble organic pollutants. - Graphical abstract: Hierarchical hollow microspheres from ZnO-graphene nanocomposites as reusable adsorbent of organic water pollutant. - Highlights: • Prepared hollow microspheres of ZnO-graphene nanocomposite (ZG) by solution route. • By optimizing graphene content, ZG shows improved adsorption capacity of dyes. • ZG shows a highly efficient photocatalytic activity of the dye pollutants. • It acts as a reusable adsorbent of the pollutants.

  4. optimizing compression zone of flanged hollow cored concrete ...

    African Journals Online (AJOL)

    eobe

    effective flange width and the hollow core position in the compression zone of a plain concrete beam with a point ... rectangular concrete beam to the topmost fiber could ... concrete. The results obtained by finite element solution showed good agreement with experimental results. In an investigation of thirty-nine reinforced.

  5. Highly permeable and mechanically robust silicon carbide hollow fiber membranes

    NARCIS (Netherlands)

    de Wit, Patrick; Kappert, Emiel; Lohaus, T.; Wessling, Matthias; Nijmeijer, Arian; Benes, Nieck Edwin

    2015-01-01

    Silicon carbide (SiC) membranes have shown large potential for applications in water treatment. Being able to make these membranes in a hollow fiber geometry allows for higher surface-to-volume ratios. In this study, we present a thermal treatment procedure that is tuned to produce porous silicon

  6. Facile synthesis of ZnO hollow fibres

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. In this paper, cotton fibres were used as bio-template to successfully synthesize new ceramic mate- rials, ZnO hollow fibres and in an effort to explore the synthesis condition, and simplify the synthesis procedure. In this synthesis, a direct thermal decomposition of zinc acetate dihydrate coated on the surface of ...

  7. Characterization of silane coated hollow sphere alumina-reinforced ...

    Indian Academy of Sciences (India)

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites ...

  8. Hollow cathode heater development for the Space Station plasma contactor

    Science.gov (United States)

    Soulas, George C.

    1993-01-01

    A hollow cathode-based plasma contactor has been selected for use on the Space Station. During the operation of the plasma contactor, the hollow cathode heater will endure approximately 12000 thermal cycles. Since a hollow cathode heater failure would result in a plasma contactor failure, a hollow cathode heater development program was established to produce a reliable heater design. The development program includes the heater design, process documents for both heater fabrication and assembly, and heater testing. The heater design was a modification of a sheathed ion thruster cathode heater. Three heaters have been tested to date using direct current power supplies. Performance testing was conducted to determine input current and power requirements for achieving activation and ignition temperatures, single unit operational repeatability, and unit-to-unit operational repeatability. Comparisons of performance testing data at the ignition input current level for the three heaters show the unit-to-unit repeatability of input power and tube temperature near the cathode tip to be within 3.5 W and 44 degrees C, respectively. Cyclic testing was then conducted to evaluate reliability under thermal cycling. The first heater, although damaged during assembly, completed 5985 ignition cycles before failing. Two additional heaters were subsequently fabricated and have completed 3178 cycles to date in an on-going test.

  9. EM-wave absorption properties of hollow spiral iron particles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenqiang, E-mail: zwqcau@gmail.com [College of Engineering, China Agricultural University, Beijing 100083 (China); Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

    2015-12-15

    Hollow iron spiral particles were fabricated successfully by thermal decomposition method, and they were heat-treated at different temperatures in N{sub 2} atmosphere. The electromagnetic wave absorption properties of hollow iron spiral particles were investigated ranging between 1 GHz and 18 GHz. The results indicated that the phase structures of the particles changed from amorphous to nanocrystal with the treating temperature rising, also causing the significant change in electromagnetic parameters and the reflection loss. The reflection loss could reach −33 dB at 16.2 GHz, indicating that the hollow iron spiral particles had the potential to be used in prepare the a high property EM-wave absorber. - Highlights: • Hollow iron spiral particles were fabricated by thermal decomposition method. • The particles changed from amorphous to nanocrystals with heat-treatment. • Particles’ EM-parameters have a great change after high temperature heat-treatment. • RL results show the particles have potential to be high property EM-wave absorber.

  10. Synthesis of Porous Inorganic Hollow Fibers without Harmful Solvents

    NARCIS (Netherlands)

    Shukla, Sushumna; de Wit, Patrick; Luiten-Olieman, Maria W.J.; Kappert, Emiel; Nijmeijer, Arian; Benes, Nieck Edwin

    2015-01-01

    A route for the fabrication of porous inorganic hollow fibers with high surface-area-to-volume ratio that avoids harmful solvents is presented. The approach is based on bio-ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal

  11. Fabrication of polystyrene hollow microspheres as laser fusion ...

    Indian Academy of Sciences (India)

    Centre for Advanced Technology (CAT), Indore 452 013, India. MS received 26 June 2001; revised 7 December 2001. Abstract. Inertial confinement fusion, frequently referred to as ICF, inertial fusion, or laser fu- sion, is a means of producing energy by imploding small hollow microspheres containing thermo- nuclear fusion ...

  12. Fabrication of polystyrene hollow microspheres as laser fusion ...

    Indian Academy of Sciences (India)

    Inertial confinement fusion, frequently referred to as ICF, inertial fusion, or laser fusion, is a means of producing energy by imploding small hollow microspheres containing thermonuclear fusion fuel. Polymer microspheres, which are used as fuel containers, can be produced by solution-based micro-encapsulation technique ...

  13. Silicon micromachined hollow microneedles for transdermal liquid transfer

    NARCIS (Netherlands)

    Gardeniers, Johannes G.E.; Berenschot, Johan W.; de Boer, Meint J.; Yeshurun, Y.; Hefetz, M.; van 't Oever, R.; van den Berg, Albert

    2002-01-01

    This paper presents an improved design and fabrication process [ 13 for hollow micro needles with the proper mechanical strength and sharpness to be applied for painless transdermal transfer of liquids. Tests have shown that liquids like blood are drawn into the needle by capillary forces, reducing

  14. Ferroelectric hollow particles obtained by solid-state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Buscaglia, Maria Teresa; Buscaglia, Vincenzo; Viviani, Massimo; Nanni, Paolo [Institute of Energetics and Interphases, National Research Council, Via De Marini 6, I-16149 Genoa (Italy); Dondero, Giovanni [Institute for Macromolecular Studies, National Research Council, Via De Marini 6, I-16149 Genoa (Italy); Roehrig, Serge; Ruediger, Andreas [Institute of Solid State Research, Centre of Nanoelectronic Systems for Information Technology, Research Centre Juelich, 52425 Juelich (Germany)], E-mail: v.buscaglia@ge.ieni.cnr.it

    2008-06-04

    Hollow particles of barium titanate were obtained by a two-step process combining colloidal chemistry and solid-state reaction. BaCO{sub 3} crystals (size {approx}1 {mu}m) suspended in a peroxy-Ti(IV) aqueous solution were coated with an amorphous TiO{sub 2} shell using a precipitation process. Calcination of the BaCO{sub 3}-TiO{sub 2} core-shell particles at 700 deg. C resulted in the formation of BaTiO{sub 3} hollow particles (shell thickness of {approx}70 nm) which retain the morphology of the BaCO{sub 3} crystals. Formation of the cavity occurs because out-diffusion of the core phase is much faster than in-diffusion of the shell material. X-ray diffraction (XRD) and Raman spectroscopy indicate that the hollow particles possess a tetragonal ferroelectric structure with axial ratio c/a = 1.005. Piezoresponse force microscopy has shown strong piezoactivity and 180 deg. ferroelectric domains. The process described provides a general route to fabricate hollow ferroelectric structures of several compounds.

  15. Ferroelectric hollow particles obtained by solid-state reaction.

    Science.gov (United States)

    Buscaglia, Maria Teresa; Buscaglia, Vincenzo; Viviani, Massimo; Dondero, Giovanni; Röhrig, Serge; Rüdiger, Andreas; Nanni, Paolo

    2008-06-04

    Hollow particles of barium titanate were obtained by a two-step process combining colloidal chemistry and solid-state reaction. BaCO(3) crystals (size ≈1 µm) suspended in a peroxy-Ti(IV) aqueous solution were coated with an amorphous TiO(2) shell using a precipitation process. Calcination of the BaCO(3)@TiO(2) core-shell particles at 700 °C resulted in the formation of BaTiO(3) hollow particles (shell thickness of ≈70 nm) which retain the morphology of the BaCO(3) crystals. Formation of the cavity occurs because out-diffusion of the core phase is much faster than in-diffusion of the shell material. X-ray diffraction (XRD) and Raman spectroscopy indicate that the hollow particles possess a tetragonal ferroelectric structure with axial ratio c/a = 1.005. Piezoresponse force microscopy has shown strong piezoactivity and 180° ferroelectric domains. The process described provides a general route to fabricate hollow ferroelectric structures of several compounds.

  16. Lanthanide-doped hollow nanomaterials as theranostic agents.

    Science.gov (United States)

    Kang, Xiaojiao; Li, Chunxia; Cheng, Ziyong; Ma, Ping'an; Hou, Zhiyao; Lin, Jun

    2014-01-01

    The field of theranostics has sprung up to achieve personalized medicine. The theranostics fuses diagnostic and therapeutic functions, empowering early diagnosis, targeted drug delivery, and real-time monitoring of treatment effect into one step. One particularly attractive class of nanomaterials for theranostic application is lanthanide-doped hollow nanomaterials (LDHNs). Because of the existence of lanthanide ions, LDHNs show outstanding fluorescent and paramagnetic properties, enabling them to be used as multimodal bioimaging agents. Synchronously, the huge interior cavities of LDHNs are able to be applied as efficacious tools for storage and delivery of therapeutic agents. The LDHNs can be divided into two types based on difference of component: single-phase lanthanide-doped hollow nanomaterials and lanthanide-doped hollow nanocomposites. We describe the synthesis of first kind of nanomaterials by use of hard template, soft template, template-free, and self-sacrificing template method. For lanthanide-doped hollow nanocomposites, we divide the preparation strategies into three kinds (one-step, two-step, and multistep method) according to the synthetic procedures. Furthermore, we also illustrate the potential bioapplications of these LDHNs, including biodetection, imaging (fluorescent imaging and magnetic resonance imaging), drug/gene delivery, and other therapeutic applications. © 2013 Wiley Periodicals, Inc.

  17. Hollow-core photonic band gap fibers for particle acceleration

    Directory of Open Access Journals (Sweden)

    Robert J. Noble

    2011-12-01

    Full Text Available Photonic band gap (PBG dielectric fibers with hollow cores are being studied both theoretically and experimentally for use as laser driven accelerator structures. The hollow core functions as both a longitudinal waveguide for the transverse-magnetic (TM accelerating fields and a channel for the charged particles. The dielectric surrounding the core is permeated by a periodic array of smaller holes to confine the mode, forming a photonic crystal fiber in which modes exist in frequency passbands, separated by band gaps. The hollow core acts as a defect which breaks the crystal symmetry, and so-called defect, or trapped modes having frequencies in the band gap will only propagate near the defect. We describe the design of 2D hollow-core PBG fibers to support TM defect modes with high longitudinal fields and high characteristic impedance. Using as-built dimensions of industrially made fibers, we perform a simulation analysis of prototype PBG fibers with dimensions appropriate for speed-of-light TM modes.

  18. Shear and anchorage behaviour of fire exposed hollow core slabs

    NARCIS (Netherlands)

    Fellinger, J.

    2005-01-01

    The fire resistance of hollow core slabs is currently assessed considering flexural failure only. However, fire tests show that shear or anchorage failure can also govern the load bearing behaviour. This paper is based on the dissertation by the author1 and discusses existing and new fire tests. It

  19. Tensile Strength of GFRP Reinforcing Bars with Hollow Section

    Directory of Open Access Journals (Sweden)

    Young-Jun You

    2015-01-01

    Full Text Available Fiber reinforced polymer (FRP has been proposed to replace steel as a reinforcing bar (rebar due to its high tensile strength and noncorrosive material properties. One obstacle in using FRP rebars is high price. Generally FRP is more expensive than conventional steel rebar. There are mainly two ways to reduce the cost. For example, one is making the price of each composition cost of FRP rebar (e.g., fibers, resin, etc. lower than steel rebar. Another is making an optimized design for cross section and reducing the material cost. The former approach is not easy because the steel price is very low in comparison with component materials of FRP. For the latter approach, the cost could be cut down by reducing the material cost. Therefore, an idea of making hollow section over the cross section of FRP rebar was proposed in this study by optimizing the cross section design with acceptable tensile performance in comparison with steel rebar. In this study, glass reinforced polymer (GFRP rebars with hollow section and 19 mm of outer diameter were manufactured and tested to evaluate the tensile performance in accordance with the hollowness ratio. From the test results, it was observed that the tensile strength decreased almost linearly with increase of hollowness ratio and the elastic modulus decreased nonlinearly.

  20. Investigation of torsional vibrations in thick walled hollow poroelastic ...

    Indian Academy of Sciences (India)

    Abstract. This paper deals with the study of torsional vibrations of thick walled hollow poroelastic cylinder using Biot's extension theory. Considering the boundaries to be stress free, the frequency equation is obtained in the presence of dissipation which is transcendental and complex valued in nature. In the special case of ...