WorldWideScience

Sample records for membrane hole array

  1. Determination of stress multipliers for thin perforated plates with square array of holes

    International Nuclear Information System (INIS)

    Bhattacharya, A.; Murli, B.; Kushwaha, H.S.

    1991-01-01

    The peak stress multipliers are required to determine the maximum stresses in perforated plates for the realistic evaluation of their fatigue life. The Section III of ASME Boiler and Pressure Vessels Code does not provide any information about such multipliers to be used in thin perforated plates with square penetration pattern. Although such multipliers for membrane loadings are available in literature, they were obtained either by classical analysis or by photoelastic experiments and there is no significant finite element analysis in this area. Also it has been a common practice among designers to apply the same multipliers for loads producing bending type of stress. The stress multipliers in bending are lower than those in membrane. Therefore a reduction of resultant peak stress occurs if proper stress multipliers are used for bending. The present paper is aimed at developing a finite element technique which can be used for determining the peak stress multipliers in thin plates for membrane as well as bending loads. A quarter symmetric part of a 3 x 3 square array was chosen for the analysis. The results were obtained by computer programs PAFEC and COSMOS/M using 2-D plane stress elements for the membrane and degenerated 3-D shell element for the bending part. The results for the membrane are compared with Bailey, Hicks and Hulbert and with Meijers' finite element results for the bending part. A study was made at the initial stage by analysing a 6 x 6 square array to see the effect of holes beyond one pitch, which were left out by the 3 x 3 array and the effect of additional holes was found to be negligible. Therefore it was decided to carry out further analysis with 3 x 3 square array. Photoelastic experiments were also performed to validate the results obtained by theoretical analysis. (author)

  2. Black holes: the membrane paradigm

    International Nuclear Information System (INIS)

    Thorne, K.S.; Price, R.H.; Macdonald, D.A.

    1986-01-01

    The physics of black holes is explored in terms of a membrane paradigm which treats the event horizon as a two-dimensional membrane embedded in three-dimensional space. A 3+1 formalism is used to split Schwarzschild space-time and the laws of physics outside a nonrotating hole, which permits treatment of the atmosphere in terms of the physical properties of thin slices. The model is applied to perturbed slowly or rapidly rotating and nonrotating holes, and to quantify the electric and magnetic fields and eddy currents passing through a membrane surface which represents a stretched horizon. Features of tidal gravitational fields in the vicinity of the horizon, quasars and active galalctic nuclei, the alignment of jets perpendicular to accretion disks, and the effects of black holes at the center of ellipsoidal star clusters are investigated. Attention is also given to a black hole in a binary system and the interactions of black holes with matter that is either near or very far from the event horizon. Finally, a statistical mechanics treatment is used to derive a second law of thermodynamics for a perfectly thermal atmosphere of a black hole

  3. Black Hole Complementary Principle and Noncommutative Membrane

    International Nuclear Information System (INIS)

    Wei Ren

    2006-01-01

    In the spirit of black hole complementary principle, we have found the noncommutative membrane of Scharzchild black holes. In this paper we extend our results to Kerr black hole and see the same story. Also we make a conjecture that spacetimes are noncommutative on the stretched membrane of the more general Kerr-Newman black hole.

  4. The membrane paradigm for black holes

    International Nuclear Information System (INIS)

    Price, R.H.; Thorne, K.S.

    1988-01-01

    It is now widely accepted that black holes exist and have an astrophysical role, in particular as the likely power source of quasars. To understand this role with ease, the authors and their colleagues have developed a new paradigm for black holes - a new way to picture, think about and describe them. As far as possible it treats black holes as ordinary astrophysical objects, made of real material. A black hole in this description is a spherical or oblate surface made of a thin, electrically conducting membrane. It was the author's quest to understand the Blandford-Znajek process intuitively that led them to create the membrane paradigm. Their strategy was to translate the general-relativistic mathematics of black holes into the same language of three-dimensional space that is used for magnetized plasmas and to create a new set of black-hole diagrams and pictures to go along with the language. 9 figs

  5. Enhanced Circular Dichroism of Gold Bilayered Slit Arrays Embedded with Rectangular Holes.

    Science.gov (United States)

    Zhang, Hao; Wang, Yongkai; Luo, Lina; Wang, Haiqing; Zhang, Zhongyue

    2017-01-01

    Gold bilayered slit arrays with rectangular holes embedded into the metal surface are designed to enhance the circular dichroism (CD) effect of gold bilayered slit arrays. The rectangular holes in these arrays block electric currents and generate localized surface plasmons around these holes, thereby strengthening the CD effect. The CD enhancement factor depends strongly on the rotational angle and the structural parameters of the rectangular holes; this factor can be enhanced further by drilling two additional rectangular holes into the metal surfaces of the arrays. These results help facilitate the design of chiral structures to produce a strong CD effect and large electric fields.

  6. Large scale biomimetic membrane arrays

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard; Perry, Mark; Vogel, Jörg

    2009-01-01

    To establish planar biomimetic membranes across large scale partition aperture arrays, we created a disposable single-use horizontal chamber design that supports combined optical-electrical measurements. Functional lipid bilayers could easily and efficiently be established across CO2 laser micro......-structured 8 x 8 aperture partition arrays with average aperture diameters of 301 +/- 5 mu m. We addressed the electro-physical properties of the lipid bilayers established across the micro-structured scaffold arrays by controllable reconstitution of biotechnological and physiological relevant membrane...... peptides and proteins. Next, we tested the scalability of the biomimetic membrane design by establishing lipid bilayers in rectangular 24 x 24 and hexagonal 24 x 27 aperture arrays, respectively. The results presented show that the design is suitable for further developments of sensitive biosensor assays...

  7. Multiple extrafoveal macular holes following internal limiting membrane peeling

    Directory of Open Access Journals (Sweden)

    Hussain N

    2018-05-01

    Full Text Available Nazimul Hussain, Sandip Mitra Department of Ophthalmology, Al Zahra Hospital, Sharjah, United Arab Emirates Objective: Internal limiting membrane (ILM peeling has been the standard of treatment for macular holes. Besides, causing retinal nerve fiber layer surface abnormality, postoperative extrafoveal multiple retinal holes is a rare phenomenon following ILM peeling. We report an unusual complication of eight extrafoveal macular holes occurring following ILM peeling.Case presentation: A 60-year-old male presented with complaints of decreased and distorted vision in the right eye. He was diagnosed as having epiretinal membrane with lamellar macular hole. He underwent 23G pars plana vitrectomy, brilliant blue assisted ILM peeling and fluid gas exchange. Intraoperatively, ILM was found to be adherent to the underlying neurosensory retina. One month after cataract surgery, he underwent YAG capsulotomy in the right eye. He complained of visual distortion. His fundus evaluation in the right eye showed multiple (eight extrafoveal retinal holes temporal to the macula clustered together.Conclusion: This case demonstrated that peeling of ILM, especially when it is adherent to the underlying neurosensory retina, may cause unwanted mechanical trauma to the inner retina. Glial apoptosis and neuronal degeneration may presumably play a role in delayed appearance of multiple (eight extrafoveal macular holes, which has not been reported earlier. Keywords: internal limiting membrane, lamellar macular hole, full thickness macular holes, epiretinal membrane

  8. The Membrane Paradigm and black-hole thermodynamics

    International Nuclear Information System (INIS)

    Thorne, K.S.

    1986-01-01

    A brief overview is given of the theoretical underpinnings of the Membrane Paradigm for black-hole physics. Then those underpinnings are used to elucidate the Paradigm's view that the laws of black-hole thermodynamics (including the statistical origin of black-hole entropy) are just a special case of the laws of thermodynamics for an ordinary, rotating, thermal reservoir

  9. Black hole mass formula in the membrane paradigm

    Science.gov (United States)

    Lemos, José P. S.; Zaslavskii, Oleg B.

    2018-03-01

    The membrane paradigm approach adopts a timelike surface, stretched out off the null event horizon, to study several important black hole properties. We use this powerful tool to give a direct derivation of the black hole mass formula in the static and stationary cases without and with electric field. Since here the membrane is a self-gravitating material system, we go beyond the usual applicability on test particles and test fields of the paradigm.

  10. Large-Aperture Membrane Active Phased-Array Antennas

    Science.gov (United States)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  11. Sub-threshold wavelength splitting in coupled photonic crystal cavity arrays

    DEFF Research Database (Denmark)

    Schubert, Martin; Frandsen, Lars Hagedorn; Skovgård, Troels Suhr

    Coupled photonic crystal (PhC) cavity arrays have recently been found to increase the output power of nanocavity lasers by coherent coupling of a large number of cavities [1]. We have measured the sub-threshold behaviour of such structures in order to gain better understanding of the mode structure....... PhC structures defined by circular holes placed in a quadratic lattice with pitch a=280 nm were fabricated in a GaAs membrane and cavity arrays were realized by introducing single missing holes with intracavity hole distances of two, three, five and seven holes. Arrays with different number...... of coupled cavities were fabricated and characterized using photoluminescence measurements of quantum dots embedded in the GaAs PhC membrane. Since the collection spot size was ~2.5 μm and therefore small compared to the arrays, spectra were taken at several positions of each array....

  12. Domain wall energy landscapes in amorphous magnetic films with asymmetric arrays of holes

    International Nuclear Information System (INIS)

    Alija, A; Perez-Junquera, A; RodrIguez-RodrIguez, G; Velez, M; Alameda, J M; MartIn, J I; Marconi, V I; Kolton, A B; Parrondo, J M R; Anguita, J V

    2009-01-01

    Arrays of asymmetric holes have been defined in amorphous Co-Si films by e-beam lithography in order to study domain wall motion across the array subject to the asymmetric pinning potential created by the holes. Experimental results on Kerr effect magnetooptical measurements and hysteresis loops are compared with micromagnetic simulations in films with arrays of triangular holes. These show that the potential asymmetry favours forward wall propagation for flat walls but, if the wall contains a kink, net backward wall propagation is preferred at low fields, in agreement with minor loop experiments. The difference between the fields needed for forward and backward flat wall propagation increases as the size of the triangular holes is reduced, becoming maximum for 1 μm triangles, which is the characteristic length scale set by domain wall width.

  13. Domain wall energy landscapes in amorphous magnetic films with asymmetric arrays of holes

    Science.gov (United States)

    Alija, A.; Pérez-Junquera, A.; Rodríguez-Rodríguez, G.; Vélez, M.; Marconi, V. I.; Kolton, A. B.; Anguita, J. V.; Alameda, J. M.; Parrondo, J. M. R.; Martín, J. I.

    2009-02-01

    Arrays of asymmetric holes have been defined in amorphous Co-Si films by e-beam lithography in order to study domain wall motion across the array subject to the asymmetric pinning potential created by the holes. Experimental results on Kerr effect magnetooptical measurements and hysteresis loops are compared with micromagnetic simulations in films with arrays of triangular holes. These show that the potential asymmetry favours forward wall propagation for flat walls but, if the wall contains a kink, net backward wall propagation is preferred at low fields, in agreement with minor loop experiments. The difference between the fields needed for forward and backward flat wall propagation increases as the size of the triangular holes is reduced, becoming maximum for 1 µm triangles, which is the characteristic length scale set by domain wall width.

  14. Multiple extrafoveal macular holes following internal limiting membrane peeling.

    Science.gov (United States)

    Hussain, Nazimul; Mitra, Sandip

    2018-01-01

    Internal limiting membrane (ILM) peeling has been the standard of treatment for macular holes. Besides, causing retinal nerve fiber layer surface abnormality, postoperative extrafoveal multiple retinal holes is a rare phenomenon following ILM peeling. We report an unusual complication of eight extrafoveal macular holes occurring following ILM peeling. A 60-year-old male presented with complaints of decreased and distorted vision in the right eye. He was diagnosed as having epiretinal membrane with lamellar macular hole. He underwent 23G pars plana vitrectomy, brilliant blue assisted ILM peeling and fluid gas exchange. Intraoperatively, ILM was found to be adherent to the underlying neurosensory retina. One month after cataract surgery, he underwent YAG capsulotomy in the right eye. He complained of visual distortion. His fundus evaluation in the right eye showed multiple (eight) extrafoveal retinal holes temporal to the macula clustered together. This case demonstrated that peeling of ILM, especially when it is adherent to the underlying neurosensory retina, may cause unwanted mechanical trauma to the inner retina. Glial apoptosis and neuronal degeneration may presumably play a role in delayed appearance of multiple (eight) extrafoveal macular holes, which has not been reported earlier.

  15. Transmission of light through periodic arrays of square holes : from a metallic wire mesh to an array of tiny holes

    NARCIS (Netherlands)

    Bravo-Abad, J.; Martin-Moreno, L.; Garcia-Vidal, F.J.; Hendry, E.; Gómez Rivas, J.

    2007-01-01

    A complete landscape is presented of the electromagnetic coupling between square holes forming a two-dimensional periodic array in a metallic film. By combining both experimental and theoretical results along with a first-principles Fano model, we study the crossover between the physics of metallic

  16. Preparing nano-hole arrays by using porous anodic aluminum oxide nano-structural masks for the enhanced emission from InGaN/GaN blue light-emitting diodes

    International Nuclear Information System (INIS)

    Nguyen, Hoang-Duy; Nguyen, Hieu Pham Trung; Lee, Jae-jin; Mho, Sun-Il

    2012-01-01

    We report on the achievement of the enhanced cathodoluminescence (CL) from InGaN/GaN light-emitting diodes (LEDs) by using roughening surface. Nanoporous anodic aluminum oxide (AAO) mask was utilized to form nano-hole arrays on the surface of InGaN/GaN LEDs. AAO membranes with ordered hexagonal structures were fabricated from aluminum foils by a two-step anodization method. The average pore densities of ∼1.0 × 10 10 cm −2 and 3.0 × 10 10 cm −2 were fabricated with the constant anodization voltages of 25 and 40 V, respectively. Anodic porous alumina film with a thickness of ∼600 nm has been used as a mask for the induced couple plasma etching process to fabricate nano-hole arrays on the LED surface. Diameter and depth of nano-holes can be controlled by varying the etching duration and/or the diameter of AAO membranes. Due to the reduction of total internal reflection obtained in the patterned samples, we have observed that the cathodoluminescence intensity of LEDs with nanoporous structures is increased up to eight times compared to that of samples without using nanoporous structure. (paper)

  17. Preparing nano-hole arrays by using porous anodic aluminum oxide nano-structural masks for the enhanced emission from InGaN/GaN blue light-emitting diodes

    Science.gov (United States)

    Nguyen, Hoang-Duy; Nguyen, Hieu Pham Trung; Lee, Jae-jin; Mho, Sun-Il

    2012-12-01

    We report on the achievement of the enhanced cathodoluminescence (CL) from InGaN/GaN light-emitting diodes (LEDs) by using roughening surface. Nanoporous anodic aluminum oxide (AAO) mask was utilized to form nano-hole arrays on the surface of InGaN/GaN LEDs. AAO membranes with ordered hexagonal structures were fabricated from aluminum foils by a two-step anodization method. The average pore densities of ˜1.0 × 1010 cm-2 and 3.0 × 1010 cm-2 were fabricated with the constant anodization voltages of 25 and 40 V, respectively. Anodic porous alumina film with a thickness of ˜600 nm has been used as a mask for the induced couple plasma etching process to fabricate nano-hole arrays on the LED surface. Diameter and depth of nano-holes can be controlled by varying the etching duration and/or the diameter of AAO membranes. Due to the reduction of total internal reflection obtained in the patterned samples, we have observed that the cathodoluminescence intensity of LEDs with nanoporous structures is increased up to eight times compared to that of samples without using nanoporous structure.

  18. Eccentric Macular Hole after Pars Plana Vitrectomy for Epiretinal Membrane Without Internal Limiting Membrane Peeling: A Case Report.

    Science.gov (United States)

    Garnavou-Xirou, Christina; Xirou, Tina; Kabanarou, Stamatina; Gkizis, Ilias; Velissaris, Stavros; Chatziralli, Irini

    2017-12-01

    Postoperative eccentric macular hole formation is an uncommon complication after pars plana vitrectomy (PPV) without internal limiting membrane (ILM) peeling for the treatment of epiretinal membrane (ERM). We present a case of eccentric macular hole formation after PPV for ERM without ILM peeling. A 68-year-old male patient presented with ERM and visual acuity of 6/24 in his left eye. He underwent 23-gauge PPV without ILM peeling for treatment of ERM. One week postoperatively the retina was attached and the epiretinal membrane was successfully removed, while visual acuity was 6/9. One month after PPV, a single eccentric retinal hole below the macula was detected using fundoscopy and subsequently confirmed by optical coherence tomography. At this time the visual acuity was 6/9 and the patient reported no symptoms. No further intervention was attempted and at the 9-month follow-up, the visual acuity and the size of the eccentric macular hole remained stable. Eccentric macular holes can be developed after PPV even without ILM peeling and are usually managed conservatively by observation.

  19. Membrane paradigm and entropy of black holes in the Euclidean action approach

    International Nuclear Information System (INIS)

    Lemos, Jose P. S.; Zaslavskii, Oleg B.

    2011-01-01

    The membrane paradigm approach to black holes fixes in the vicinity of the event horizon a fictitious surface, the stretched horizon, so that the spacetime outside remains unchanged and the spacetime inside is vacuum. Using this powerful method, several black hole properties have been found and settled, such as the horizon's viscosity, electrical conductivity, resistivity, as well as other properties. On the other hand, the Euclidean action approach to black hole spacetimes has been very fruitful in understanding black hole entropy. Combining both the Euclidean action and membrane paradigm approaches, a direct derivation of the black hole entropy is given. In the derivation, it is considered that the only fields present are the gravitational and matter fields, with no electric field.

  20. Postoperative eccentric macular holes after vitrectomy and internal limiting membrane peeling.

    Science.gov (United States)

    Brouzas, Dimitrios; Dettoraki, Maria; Lavaris, Anastasios; Kourvetaris, Dimitrios; Nomikarios, Nikolaos; Moschos, Marilita M

    2017-06-01

    The purpose of this study was to describe the incidence, clinical characteristics, and outcome of eccentric macular holes presenting after vitrectomy and internal limiting membrane (ILM) peeling for the treatment of macular pathology and discuss the pathogenesis of holes formation. A retrospective, noncomparative, interventional case-series study of five patients who developed eccentric macular holes postoperatively following vitrectomy in 198 consecutive patients who underwent ILM peeling for idiopathic macular hole and epiretinal membrane formation between 2008 and 2015. Five patients (2.5 %) developed full-thickness eccentric macular holes postoperatively. Three patients presented with a single eccentric macular hole, one patient had an eccentric hole after a failed idiopathic macular hole surgery and one patient developed four eccentric macular holes. The mean diameter of the holes was 584 μm (range 206-1317 μm) and the average time of holes formation after vitrectomy was 27.7 weeks (range 1-140 weeks). Postoperative best-corrected visual acuity ranged from "counting fingers" to 20/25. The eyes with the holes distant from the fovea had the best final visual acuity. No further intervention was attempted and no complications occurred. The mean follow-up time was 26.8 months. The postoperative macular holes after vitrectomy and ILM peeling were variable in number, size, and time of appearance but remained stable and were not associated with any complications. The pathogenesis of macular holes is most consistent with contraction of the residual ILM or secondary epimacular proliferation probably stimulated by ILM peeling.

  1. Composite vortex ordering in superconducting films with arrays of blind holes

    International Nuclear Information System (INIS)

    Berdiyorov, G R; Milosevic, M V; Peeters, F M

    2009-01-01

    The pinning properties of a superconducting thin film with a square array of blind holes are studied using the nonlinear Ginzburg-Landau theory. Although blind holes provide a weaker pinning potential than holes (also called antidots), several novel vortex structures are predicted for different size and thickness of the blind holes. Orientational dimer and trimer vortex states as well as concentric vortex shells can nucleate in the blind holes. In addition, we predict the stabilization of giant vortices that may be located both in the pinning centers and/or at the interstitial sites, as well as the combination of giant vortices with sets of individual vortices. For large blind holes, local vortex shell structures inside the blind holes may transfer their symmetry to interstitial vortices as well. The subtle interplay of shell formation and traditional Abrikosov vortex lattices inside the blind holes is also studied for different numbers of trapped vortices.

  2. Self-assembled ordered carbon-nanotube arrays and membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Siegal, Michael P.; Yelton, William Graham

    2004-11-01

    Imagine free-standing flexible membranes with highly-aligned arrays of carbon nanotubes (CNTs) running through their thickness. Perhaps with both ends of the CNTs open for highly controlled nanofiltration? Or CNTs at heights uniformly above a polymer membrane for a flexible array of nanoelectrodes or field-emitters? How about CNT films with incredible amounts of accessible surface area for analyte adsorption? These self-assembled crystalline nanotubes consist of multiple layers of graphene sheets rolled into concentric cylinders. Tube diameters (3-300 nm), inner-bore diameters (2-15 nm), and lengths (nanometers - microns) are controlled to tailor physical, mechanical, and chemical properties. We proposed to explore growth and characterize nanotube arrays to help determine their exciting functionality for Sandia applications. Thermal chemical vapor deposition growth in a furnace nucleates from a metal catalyst. Ordered arrays grow using templates from self-assembled hexagonal arrays of nanopores in anodized-aluminum oxide. Polymeric-binders can mechanically hold the CNTs in place for polishing, lift-off, and membrane formation. The stiffness, electrical and thermal conductivities of CNTs make them ideally suited for a wide-variety of possible applications. Large-area, highly-accessible gas-adsorbing carbon surfaces, superb cold-cathode field-emission, and unique nanoscale geometries can lead to advanced microsensors using analyte adsorption, arrays of functionalized nanoelectrodes for enhanced electrochemical detection of biological/explosive compounds, or mass-ionizers for gas-phase detection. Materials studies involving membrane formation may lead to exciting breakthroughs in nanofiltration/nanochromatography for the separation of chemical and biological agents. With controlled nanofilter sizes, ultrafiltration will be viable to separate and preconcentrate viruses and many strains of bacteria for 'down-stream' analysis.

  3. A study of angle dependent surface plasmon polaritons in nano-hole array structures

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnan, Shankar [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Lawson Health Research Institute, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Najiminaini, Mohamadreza; Carson, Jeffrey J. L. [Lawson Health Research Institute, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

    2016-07-21

    We report that the light-matter interaction in metallic nano-hole array structures possess a subwavelength hole radius and periodicity. The transmission coefficient for nano-hole array structures was measured for different angles of incidence of light. Each measured transmission spectrum had several peaks due to surface plasmon polaritons. A theory of the transmission coefficient was developed based on the quantum density matrix method. It was found that the location of the surface plasmon polariton and the heights of the spectral peaks were dependent on the angle of incidence of light. Good agreement was observed between the experimental and theoretical results. This property of these structures has opened up new possibilities for sensing applications.

  4. Superconducting nanowire networks formed on nanoporous membrane substrates

    Science.gov (United States)

    Luo, Qiong

    Introducing a regular array of holes into superconducting thin films has been actively pursued to stabilize and pin the vortex lattice against external driving forces, enabling higher current capabilities. If the width of the sections between neighboring holes is comparable to the superconducting coherence length, the circulation of the Cooper pairs in around the holes in the presence of a magnetic field can also produce the Little-Parks effect, i.e. periodic oscillation of the critical temperature. These two mechanisms, commensurate vortex pinning enhancement by the hole-array and the critical temperature oscillations of a wire network due to Little-Parks effect can induce similar experimental observations such as magnetoresistance oscillation and enhancement of the critical current at specific magnetic fields. This dissertation work investigates the effect of a hole-array on the properties of superconducting films deposited onto nanoporous substrates. Experiments on anisotropies of the critical temperature for niobium films on anodic aluminum oxide membrane substrates containing a regular hole-array reveal that the critical temperature exhibits two strong anisotropic effects: Little-Parks oscillations whose period varies with field direction superimposed on a smooth background arising from one dimensional confinement by the finite lateral space between neighboring holes. The two components of the anisotropy are intrinsically linked and appear in concert. That is, the hole-array changes the dimensionality of a two-dimensional (2D) film to a network of 1D nanowire network. Network of superconducting nanowires with transverse dimensions as small as few nanometers were achieved by coating molybdenum germanium (MoGe) layer onto commercially available filtration membranes which have extremely dense nanopores. The magnetoresistance, magnetic field dependence of the critical temperature and the anisotropies of the synthesized MoGe nanowire networks can be consistently

  5. The large D black hole membrane paradigm at first subleading order

    International Nuclear Information System (INIS)

    Dandekar, Yogesh; De, Anandita; Mazumdar, Subhajit; Minwalla, Shiraz; Saha, Arunabha

    2016-01-01

    In the large D limit, and under certain circumstances, it has recently been demonstrated that black hole dynamics in asymptotically flat spacetime reduces to the dynamics of a non gravitational membrane propagating in flat D dimensional spacetime. We demonstrate that this correspondence extends to all orders in a 1/D expansion and outline a systematic method for deriving the corrected membrane equation in a power series expansion in 1/D. As an illustration of our method we determine the first subleading corrections to the membrane equations of motion. A qualitatively new effect at this order is that the divergence of the membrane velocity is nonzero and proportional to the square of the shear tensor reminiscent of the entropy current of hydrodynamics. As a test, we use our modified membrane equations to compute the corrections to frequencies of light quasinormal modes about the Schwarzschild black hole and find a perfect match with earlier computations performed directly in the gravitational bulk.

  6. The large D black hole membrane paradigm at first subleading order

    Energy Technology Data Exchange (ETDEWEB)

    Dandekar, Yogesh [Department of Theoretical Physics, Tata Institute of Fundamental Research,Homi Bhabha Road, Mumbai 400005 (India); De, Anandita [Department of Physics, Indian Institute of Science Education and Research,Dr. Homi Bhabha Road, Pashan, Pune 411008 (India); Mazumdar, Subhajit; Minwalla, Shiraz; Saha, Arunabha [Department of Theoretical Physics, Tata Institute of Fundamental Research,Homi Bhabha Road, Mumbai 400005 (India)

    2016-12-21

    In the large D limit, and under certain circumstances, it has recently been demonstrated that black hole dynamics in asymptotically flat spacetime reduces to the dynamics of a non gravitational membrane propagating in flat D dimensional spacetime. We demonstrate that this correspondence extends to all orders in a 1/D expansion and outline a systematic method for deriving the corrected membrane equation in a power series expansion in 1/D. As an illustration of our method we determine the first subleading corrections to the membrane equations of motion. A qualitatively new effect at this order is that the divergence of the membrane velocity is nonzero and proportional to the square of the shear tensor reminiscent of the entropy current of hydrodynamics. As a test, we use our modified membrane equations to compute the corrections to frequencies of light quasinormal modes about the Schwarzschild black hole and find a perfect match with earlier computations performed directly in the gravitational bulk.

  7. Surface Modifications of Support Partitions for Stabilizing Biomimetic Membrane Arrays

    DEFF Research Database (Denmark)

    Perry, Mark; Hansen, Jesper Schmidt; Jensen, Karin Bagger Stibius

    2011-01-01

    with a high signal-to-noise (s/n) ratio. We demonstratesd this by reconstituting gA and α-hemolysin (α-HL) into BLM arrays. The improvement in membrane array lifetime and s/n ratio demonstrates that surface plasma polymerization of the supporting partition can be used to increase the stability of biomimetic......Black lipid membrane (BLM) formation across apertures in an ethylene tetra-fluoroethylene (ETFE) partition separating two aqueous compartments is an established technique for the creation of biomimetic membranes. Recently multi-aperture BLM arrays have attracted interest and in order to increase...... BLM array stability we studied the effect of covalently modifying the partition substrate using surface plasma polymerization with hydrophobic n-hexene, 1-decene and hexamethyldisiloxane (HMDSO) as modification groups. Average lifetimes across singlesided HMDSO modified partitions or using 1-decene...

  8. Ultrafast optical control of terahertz surface plasmons in subwavelength hole-arrays at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Abul Kalam [Los Alamos National Laboratory; Chen, Hou - Tong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; O' Hara, John [Los Alamos National Laboratory

    2010-12-10

    Extraordinary optical transmission through subwavelength metallic hole-arrays has been an active research area since its first demonstration. The frequency selective resonance properties of subwavelength metallic hole arrays, generally known as surface plasmon polaritons, have potential use in functional plasmonic devices such as filters, modulators, switches, etc. Such plasmonic devices are also very promising for future terahertz applications. Ultrafast switching or modulation of the resonant behavior of the 2-D metallic arrays in terahertz frequencies is of particular interest for high speed communication and sensing applications. In this paper, we demonstrate optical control of surface plasmon enhanced resonant terahertz transmission in two-dimensional subwavelength metallic hole arrays fabricated on gallium arsenide based substrates. Optically pumping the arrays creates a conductive layer in the substrate reducing the terahertz transmission amplitude of both the resonant mode and the direct transmission. Under low optical fluence, the terahertz transmission is more greatly affected by resonance damping than by propagation loss in the substrate. An ErAs:GaAs nanoisland superlattice substrate is shown to allow ultrafast control with a switching recovery time of {approx}10 ps. We also present resonant terahertz transmission in a hybrid plasmonic film comprised of an integrated array of subwavelength metallic islands and semiconductor holes. A large dynamic transition between a dipolar localized surface plasmon mode and a surface plasmon resonance near 0.8 THz is observed under near infrared optical excitation. The reversal in transmission amplitude from a stopband to a passband and up to {pi}/2 phase shift achieved in the hybrid plasmonic film make it promising in large dynamic phase modulation, optical changeover switching, and active terahertz plasmonics.

  9. Biomimetic triblock copolymer membrane arrays: a stable template for functional membrane proteins

    DEFF Research Database (Denmark)

    Gonzalez-Perez, A.; Jensen, Karin Bagger Stibius; Vissing, Thomas

    2009-01-01

    It is demonstrated that biomimetic stable triblock copolymer membrane arrays can be prepared using a scaffold containing 64 apertures of 300 μm diameter each. The membranes were made from a stock solution of block copolymers with decane as a solvent using a new deposition method. By using decane...

  10. Depth of array micro-holes with large aspect ratio in Al based cast alloy

    Science.gov (United States)

    Jin, Meiling; Qu, Yingdong; Li, Rongde

    2018-03-01

    In order to study on the depth of array micro-holes on Al base cast alloy, micro-hole with depth of 50 mm and diameter of 0.55 mm are successfully prepared by using poor wetting between carbon and Al. Accordingly, the mold of depth is established, the results show that calculated depth of micro-hole is 53.22 mm, relative error is 6% compare with the actual measured depth, and the depth of hole exponentially increases with the increasing of distance between two micro-holes. Surface tension and metallostatic pressure of metal molten are mainly affecting factors for depth of micro-holes.

  11. Plasmonic fluorescence enhancement of DBMBF2 monomers and DBMBF2-toluene exciplexes using al-hole arrays

    NARCIS (Netherlands)

    Schmidt, T.M.; Bochenkov, V.E.; Espinoza, J.D.A.; Smits, E.C.P.; Muzafarov, A.M.; Kononevich, Y.N.; Sutherland, D.S.

    2014-01-01

    The optical properties of aluminum hole arrays fabricated via colloidal lithography were investigated. By tuning the hole diameter and hole spacing independently, their influence on the Bloch wave-surface plasmon polariton (BW-SPP) and localized surface plasmon resonances resonances (LSPR) could be

  12. Metamaterial-based theoretical description of light scattering by metallic nano-hole array structures

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada); Najiminaini, Mohamadreza; Carson, Jeffrey J. L. [Lawson Health Research Institute, St. Joseph' s Health Care, 268 Grosvenor Street, London N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London N6A 3K7 (Canada); Balakrishnan, Shankar [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada); Lawson Health Research Institute, St. Joseph' s Health Care, 268 Grosvenor Street, London N6A 4V2 (Canada); Department of Medical Biophysics, University of Western Ontario, London N6A 3K7 (Canada)

    2015-05-14

    We have experimentally and theoretically investigated the light-matter interaction in metallic nano-hole array structures. The scattering cross section spectrum was measured for three samples each having a unique nano-hole array radius and periodicity. Each measured spectrum had several peaks due to surface plasmon polaritons. The dispersion relation and the effective dielectric constant of the structure were calculated using transmission line theory and Bloch's theorem. Using the effective dielectric constant and the transfer matrix method, the surface plasmon polariton energies were calculated and found to be quantized. Using these quantized energies, a Hamiltonian for the surface plasmon polaritons was written in the second quantized form. Working with the Hamiltonian, a theory of scattering cross section was developed based on the quantum scattering theory and Green's function method. For both theory and experiment, the location of the surface plasmon polariton spectral peaks was dependant on the array periodicity and radii of the nano-holes. Good agreement was observed between the experimental and theoretical results. It is proposed that the newly developed theory can be used to facilitate optimization of nanosensors for medical and engineering applications.

  13. Simulation of polarization-dependent film with subwavelength nano-hole array

    Science.gov (United States)

    Yu, Yue; Wei, Dong; Long, Huabao; Xin, Zhaowei; Zhang, Xinyu; Wang, Haiwei; Xie, Changsheng

    2018-02-01

    When lightwave passes through a metal thin film with a periodic subwavelength hole arrays structure, its transmittance is significantly improved in the partial band compared to other wavelength. Changing the size of the hole, the period or metal material, will make the transmission curve different. Here, we add a layer of dielectric material on the surface of the metal film, such as liquid crystal(LC), by controlling voltage on LC to change the refractive index of this layer, then we can change the transmission curve, and achieve using voltage to move the transmission curve. When there is need for polarization, the holes can be made of a rectangle whose length and width are different or other shapes, for different polarization state of the light, and the film will display different transmission characteristics.

  14. Observing the dynamics of supermassive black hole binaries with pulsar timing arrays.

    Science.gov (United States)

    Mingarelli, C M F; Grover, K; Sidery, T; Smith, R J E; Vecchio, A

    2012-08-24

    Pulsar timing arrays are a prime tool to study unexplored astrophysical regimes with gravitational waves. Here, we show that the detection of gravitational radiation from individually resolvable supermassive black hole binary systems can yield direct information about the masses and spins of the black holes, provided that the gravitational-wave-induced timing fluctuations both at the pulsar and at Earth are detected. This in turn provides a map of the nonlinear dynamics of the gravitational field and a new avenue to tackle open problems in astrophysics connected to the formation and evolution of supermassive black holes. We discuss the potential, the challenges, and the limitations of these observations.

  15. Micro-hole array fluorescent sensor based on AC-Dielectrophoresis (DEP) for simultaneous analysis of nano-molecules

    Science.gov (United States)

    Kim, Hye Jin; Kang, Dong-Hoon; Lee, Eunji; Hwang, Kyo Seon; Shin, Hyun-Joon; Kim, Jinsik

    2018-02-01

    We propose a simple fluorescent bio-chip based on two types of alternative current-dielectrophoretic (AC-DEP) force, attractive (positive DEP) and repulsive (negative DEP) force, for simultaneous nano-molecules analysis. Various radius of micro-holes on the bio-chip are designed to apply the different AC-DEP forces, and the nano-molecules are concentrated inside the micro-hole arrays according to the intensity of the DEP force. The bio-chip was fabricated by Micro Electro Mechanical system (MEMS) technique, and was composed of two layers; a SiO2 layer and Ta/Pt layer were accomplished for an insulation layer and a top electrode with micro-hole arrays to apply electric fields for DEP force, respectively. Each SiO2 and Ta/Pt layers were deposited by thermal oxidation and sputtering, and micro-hole arrays were fabricated with Inductively Coupled Plasma (ICP) etching process. For generation of each positive and negative DEP at micro-holes, we applied two types of sine-wave AC voltage with different frequency range alternately. The intensity of the DEP force was controlled by the radius of the micro-hole and size of nano-molecule, and calculated with COMSOL multi-physics. Three types of nano-molecules labelled with different fluorescent dye were used and the intensity of nano-molecules was examined by the fluorescent optical analysis after applying the DEP force. By analyzing the fluorescent intensities of the nano-molecules, we verify the various nano-molecules in analyte are located successfully inside corresponding micro-holes with different radius according to their size.

  16. Biomimetic Membrane Arrays on Cast Hydrogel Supports

    DEFF Research Database (Denmark)

    Roerdink-Lander, Monique; Ibragimova, Sania; Rein Hansen, Christian

    2011-01-01

    , provides mechanical support but at the cost of small molecule transport through the membrane−support sandwich. To stabilize biomimetic membranes while allowing transport through a membrane−support sandwich, we have investigated the feasibility of using an ethylene tetrafluoroethylene (ETFE......)/hydrogel sandwich as the support. The sandwich is realized as a perforated surface-treated ETFE film onto which a hydrogel composite support structure is cast. We report a simple method to prepare arrays of lipid bilayer membranes with low intrinsic electrical conductance on the highly permeable, self......-supporting ETFE/hydrogel sandwiches. We demonstrate how the ETFE/hydrogel sandwich support promotes rapid self-thinning of lipid bilayers suitable for hosting membrane-spanning proteins....

  17. Quadrilateral Micro-Hole Array Machining on Invar Thin Film: Wet Etching and Electrochemical Fusion Machining

    Directory of Open Access Journals (Sweden)

    Woong-Kirl Choi

    2018-01-01

    Full Text Available Ultra-precision products which contain a micro-hole array have recently shown remarkable demand growth in many fields, especially in the semiconductor and display industries. Photoresist etching and electrochemical machining are widely known as precision methods for machining micro-holes with no residual stress and lower surface roughness on the fabricated products. The Invar shadow masks used for organic light-emitting diodes (OLEDs contain numerous micro-holes and are currently machined by a photoresist etching method. However, this method has several problems, such as uncontrollable hole machining accuracy, non-etched areas, and overcutting. To solve these problems, a machining method that combines photoresist etching and electrochemical machining can be applied. In this study, negative photoresist with a quadrilateral hole array pattern was dry coated onto 30-µm-thick Invar thin film, and then exposure and development were carried out. After that, photoresist single-side wet etching and a fusion method of wet etching-electrochemical machining were used to machine micro-holes on the Invar. The hole machining geometry, surface quality, and overcutting characteristics of the methods were studied. Wet etching and electrochemical fusion machining can improve the accuracy and surface quality. The overcutting phenomenon can also be controlled by the fusion machining. Experimental results show that the proposed method is promising for the fabrication of Invar film shadow masks.

  18. Localization of CO2 Leakage from a Circular Hole on a Flat-Surface Structure Using a Circular Acoustic Emission Sensor Array

    Directory of Open Access Journals (Sweden)

    Xiwang Cui

    2016-11-01

    Full Text Available Leak localization is essential for the safety and maintenance of storage vessels. This study proposes a novel circular acoustic emission sensor array to realize the continuous CO2 leak localization from a circular hole on the surface of a large storage vessel in a carbon capture and storage system. Advantages of the proposed array are analyzed and compared with the common sparse arrays. Experiments were carried out on a laboratory-scale stainless steel plate and leak signals were obtained from a circular hole in the center of this flat-surface structure. In order to reduce the influence of the ambient noise and dispersion of the acoustic wave on the localization accuracy, ensemble empirical mode decomposition is deployed to extract the useful leak signal. The time differences between the signals from the adjacent sensors in the array are calculated through correlation signal processing before estimating the corresponding distance differences between the sensors. A hyperbolic positioning algorithm is used to identify the location of the circular leak hole. Results show that the circular sensor array has very good directivity toward the circular leak hole. Furthermore, an optimized method is proposed by changing the position of the circular sensor array on the flat-surface structure or adding another circular sensor array to identify the direction of the circular leak hole. Experiential results obtained on a 100 cm × 100 cm stainless steel plate demonstrate that the full-scale error in the leak localization is within 0.6%.

  19. Macular Hole Surgery with Internal Limiting Membrane Peeling Facilitated by Membrane-Blue® versus Membrane-Blue-Dual®: A Retrospective Comparative Study

    Directory of Open Access Journals (Sweden)

    Uri Soiberman

    2016-01-01

    Full Text Available Background. This study aims to compare the outcome of macular hole (MH surgery with internal limiting membrane (ILM peeling facilitated by two different vital dyes. Methods. This was a retrospective chart review. The group designated “group-MB” underwent pars plana vitrectomy with ILM peeling facilitated by Membrane-Blue (MB, whereas in “group-MBD,” the vital dye used was Membrane-Blue-Dual (MBD. Results. Seventy-four eyes comprised the study population: 53 in group-MB and 21 in group-MBD. There was no difference in the rate of macular hole closure in group-MB or group-MBD: 71.2% closed MHs compared to 66.7%, respectively (p=0.7. Postoperative visual improvement was of a higher magnitude in the MBD group compared to the MB group: −0.34±0.81 logMAR versus 0.01±0.06 logMAR, respectively (p=0.003. Conclusions. In this study, MBD led to better visual results that may be related to better staining characteristics or lesser toxicity compared to MB.

  20. Preparation and properties of novel magnetic composite nanostructures: Arrays of nanowires in porous membranes

    International Nuclear Information System (INIS)

    Vazquez, M.; Hernandez-Velez, M.; Asenjo, A.; Navas, D.; Pirota, K.; Prida, V.; Sanchez, O.; Baldonedo, J.L.

    2006-01-01

    In the present work, we introduce our latest achievements in the development of novel highly ordered composite magnetic nanostructures employing anodized nanoporous membranes as precursor templates where long-range hexagonal symmetry is induced by self-assembling during anodization process. Subsequent processing as electroplating, sputtering or pressing are employed to prepare arrays of metallic, semiconductor or polymeric nanowires embedded in oxide or metallic membranes. Particular attention is paid to recent results on controlling the magnetic anisotropy in arrays of metallic nanowires, particularly Co, and nanohole arrays in Ni membranes

  1. Autologous transplantation of the internal limiting membrane for refractory macular holes.

    Science.gov (United States)

    Morizane, Yuki; Shiraga, Fumio; Kimura, Shuhei; Hosokawa, Mio; Shiode, Yusuke; Kawata, Tetsuhiro; Hosogi, Mika; Shirakata, Yukari; Okanouchi, Toshio

    2014-04-01

    To determine the effectiveness of autologous transplantation of the internal limiting membrane (ILM) for refractory macular holes. Prospective, interventional case series. Ten eyes of 10 consecutive patients who underwent autologous transplantation of the ILM for the treatment of refractory macular holes were studied. The primary diseases in these patients were large idiopathic macular holes that had existed for more than 1 year (4 eyes), a traumatic macular hole (1 eye), myopic foveoschisis (2 eyes), foveoschisis resulting from pit-macular syndrome (2 eyes), and proliferative diabetic retinopathy (1 eye). Apart from the 5 eyes with idiopathic or traumatic macular holes, macular holes developed in the other 5 eyes after initial vitrectomies with ILM removal. In all eyes, regular macular hole surgery failed to achieve closure. The main outcome measures used in this study were macular hole closure and best-corrected visual acuity (BCVA). Macular holes were closed successfully in 9 eyes (90%) after autologous transplantation of the ILM. The postoperative BCVAs were significantly better than the preoperative BCVAs (P = .007, paired t test). Postoperative BCVAs improved by more than 0.2 logarithm of the minimal angle of resolution units in 8 eyes (80%) and were unchanged in 2 eyes (20%). Although this is a pilot study, the results suggest that autologous transplantation of the ILM may contribute to improved anatomic and visual outcomes in the treatment of refractory macular holes and may warrant further investigation. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Hydrogels for in situ encapsulation of biomimetic membrane arrays

    DEFF Research Database (Denmark)

    Ibragimova, Sania; Jensen, Karin Bagger Stibius; Szewczykowski, Piotr Przemyslaw

    2012-01-01

    to chemically initiated hydrogels; however, for all hydrogels the permeability was several-fold higher than the water permeability of conventional reverse osmosis (RO) membranes. Lifetimes of freestanding BLM arrays in gel precursor solutions were short compared to arrays formed in buffer. However, polymerizing......Hydrogels are hydrophilic, porous polymer networks that can absorb up to thousands of times their own weight in water. They have many potential applications, one of which is the encapsulation of freestanding black lipid membranes (BLMs) for novel separation technologies or biosensor applications....... We investigated gels for in situ encapsulation of multiple BLMs formed across apertures in a hydrophobic ethylene tetrafluoroethylene (ETFE) support. The encapsulation gels consisted of networks of poly(ethylene glycol)-dimethacrylate or poly(ethylene glycol)-diacrylate polymerized using either...

  3. HKUST-1 Membranes Anchored on Porous Substrate by Hetero MIL-110 Nanorod Array Seeds.

    Science.gov (United States)

    Mao, Yiyin; Cao, Wei; Li, Junwei; Sun, Luwei; Peng, Xinsheng

    2013-09-02

    Great anchors and seeds: Hetero-seeding growth processes and anchored nanorod arrays were successfully utilized in the synthesis of HKUST-1 membranes. These arrays were firmly anchored on porous substrates by using a MIL-110 nanorod array as both the anchor and seed. The resulting HKUST-1 membranes demonstrated good separation factors for binary gases exceeding the Knudson selectivity. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Internal limiting membrane flap transposition for surgical repair of macular holes in primary surgery and in persistent macular holes.

    Science.gov (United States)

    Leisser, Christoph; Hirnschall, Nino; Döller, Birgit; Varsits, Ralph; Ullrich, Marlies; Kefer, Katharina; Findl, Oliver

    2018-03-01

    Classical or temporal internal limiting membrane (ILM) flap transposition with air or gas tamponade are current trends with the potential to improve surgical results, especially in cases with large macular holes. A prospective case series included patients with idiopathic macular holes or persistent macular holes after 23-G pars plana vitrectomy (PPV) and ILM peeling with gas tamponade. In all patients, 23-G PPV and ILM peeling with ILM flap transposition with gas tamponade and postoperative face-down position was performed. In 7 of 9 eyes, temporal ILM flap transposition combined with pedicle ILM flap could be successfully performed and macular holes were closed in all eyes after surgery. The remaining 2 eyes were converted to pedicle ILM flap transposition with macular hole closure after surgery. Three eyes were scheduled as pedicle ILM flap transposition due to previous ILM peeling. In 2 of these eyes, the macular hole could be closed with pedicle ILM flap transposition. In 3 eyes, free ILM flap transposition was performed and in 2 of these eyes macular hole could be closed after surgery, whereas in 1 eye a second surgery, performed as pedicle ILM flap transposition, was performed and led to successful macular hole closure. Use of ILM flaps in surgical repair of macular hole surgery is a new option of treatment with excellent results independent of the diameter of macular holes. For patients with persistent macular holes, pedicle ILM flap transposition or free ILM flap transposition are surgical options.

  5. Exploiting lipopolysaccharide-induced deformation of lipid bilayers to modify membrane composition and generate two-dimensional geometric membrane array patterns

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Peter G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Swingle, Kirstie L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Paxton, Walter F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nogan, John J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stromberg, Loreen R. [Univ. of New Mexico, Albuquerque, NM (United States); Firestone, Millicent A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mukundan, Harshini [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Consortium, Los Alamos, NM (United States); Montaño, Gabriel A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-05-27

    Supported lipid bilayers have proven effective as model membranes for investigating biophysical processes and in development of sensor and array technologies. The ability to modify lipid bilayers after their formation and in situ could greatly advance membrane technologies, but is difficult via current state-of-the-art technologies. Here we demonstrate a novel method that allows the controlled post-formation processing and modification of complex supported lipid bilayer arrangements, under aqueous conditions. We exploit the destabilization effect of lipopolysaccharide, an amphiphilic biomolecule, interacting with lipid bilayers to generate voids that can be backfilled to introduce desired membrane components. We further demonstrate that when used in combination with a single, traditional soft lithography process, it is possible to generate hierarchically-organized membrane domains and microscale 2-D array patterns of domains. Significantly, this technique can be used to repeatedly modify membranes allowing iterative control over membrane composition. This approach expands our toolkit for functional membrane design, with potential applications for enhanced materials templating, biosensing and investigating lipid-membrane processes.

  6. Infrared emission of a freestanding plasmonic membrane

    Science.gov (United States)

    Monshat, Hosein; Liu, Longju; McClelland, John; Biswas, Rana; Lu, Meng

    2018-01-01

    This paper reports a free-standing plasmonic membrane as a thermal emitter in the near- and mid-infrared regions. The plasmonic membrane consists of an ultrathin gold film perforated with a two-dimensional array of holes. The device was fabricated using an imprint and transfer process and fixed on a low-emissivity metal grid. The thermal radiation characteristics of the plasmonic membrane can be engineered by controlling the array period and the thickness of the gold membrane. Plasmonic membranes with two different periods were designed using electromagnetic simulation and then characterized for their transmission and infrared radiation properties. The free-standing membranes exhibit extraordinary optical transmissions with the resonant transmission coefficient as high as 76.8%. After integration with a customized heater, the membranes demonstrate narrowband thermal emission in the wavelength range of 2.5 μm to 5.5 μm. The emission signatures, including peak emission wavelength and bandwidth, are associated with the membrane geometry. The ultrathin membrane infrared emitter can be adopted in applications, such as chemical analysis and thermal imaging.

  7. Currents and radiation from the large D black hole membrane

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, Sayantani; Mandal, Anup Kumar [Department of Physics, Indian Institute of Technology Kanpur,Kalyanpur, Kanpur, Uttar Pradesh 208016 (India); Mandlik, Mangesh [Department of Theoretical Physics, Tata Institute of Fundamental Research,1, Homi Bhabha Road, Colaba, Mumbai, Maharashtra 400005 (India); Mehta, Umang [Department of Physics, Indian Institute of Technology Bombay,JVLR, Mumbai, Maharashtra 400076 (India); Minwalla, Shiraz [Department of Theoretical Physics, Tata Institute of Fundamental Research,1, Homi Bhabha Road, Colaba, Mumbai, Maharashtra 400005 (India); Sharma, Utkarsh [Department of Electrical Engineering, Indian Institute of Technology Bombay,JVLR, Mumbai, Maharashtra 400076 (India); Thakur, Somyadip [Department of Theoretical Physics, Tata Institute of Fundamental Research,1, Homi Bhabha Road, Colaba, Mumbai, Maharashtra 400005 (India)

    2017-05-18

    It has recently been demonstrated that black hole dynamics in a large number of dimensions D reduces to the dynamics of a codimension one membrane propagating in flat space. In this paper we define a stress tensor and charge current on this membrane and explicitly determine these currents at low orders in the expansion in (1/D). We demonstrate that dynamical membrane equations of motion derived in earlier work are simply conservation equations for our stress tensor and charge current. Through the paper we focus on solutions of the membrane equations which vary on a time scale of order unity. Even though the charge current and stress tensor are not parametrically small in such solutions, we show that the radiation sourced by the corresponding membrane currents is generically of order (1/(D{sup D})). In this regime it follows that the ‘near horizon’ membrane degrees of freedom are decoupled from asymptotic flat space at every perturbative order in the (1/D) expansion. We also define an entropy current on the membrane and use the Hawking area theorem to demonstrate that the divergence of the entropy current is point wise non negative. We view this result as a local form of the second law of thermodynamics for membrane motion.

  8. Does Internal Limiting Membrane Peeling in Macular Hole Surgery Improve Reading Vision?

    Directory of Open Access Journals (Sweden)

    Das Taraprasad

    2003-01-01

    Full Text Available Purpose: To document the effect of internal limiting membrane (ILM peeling in macular hole closure and reading vision. Method: Fifty-four patients with idiopathic and traumatic macular hole underwent standard vitreous surgery and received either ILM peeling (n= 25 or no ILM peeling (n= 29. The hole closure, and Snellen acuity (distant and near were recorded 12 weeks after surgery and statistically analysed. Results: The macular hole closure rate was 96% (24 of 25 and 72.4% (21 of 29 with and without ILM peeling respectively (P = 0.028. Distant vision improvement of two or more lines was recorded in 64% (16 of 25 and 51.7% (15 of 29 eyes (P = 0.417 with and without ILM peeling respectively. Near vision improvement of two or more lines was seen in 68% (17 of 25 and 41.2% (12 of 29 eyes (P = 0.048 with and without ILM peeling respectively. Conclusion: ILM peeling in macular hole surgery improves the macular hole closure rate and reading vision.

  9. Membrane viewpoint on black holes: Dynamical electromagnetic fields near the horizon

    International Nuclear Information System (INIS)

    Macdonald, D.A.; Suen, W.

    1985-01-01

    This paper is part of a series of papers with the aim of developing a complete self-consistent formalism for the treatment of electromagnetic and gravitational fields in the neighborhood of a black-hole horizon. In this membrane formalism, the horizon is treated as a closed two-dimensional membrane lying in a curved three-dimensional space, and endowed with familiar physical properties such as entropy and temperature, surface pressure and viscosity, and electrical conductivity, charge, and current. This paper develops the concept of the ''stretched horizon,'' which will be vital for both the electromagnetic and gravitational aspects of the formalism, and it presents several model problems illustrating the interaction of dynamical electromagnetic fields with stationary black-hole horizons: The field of a test charge in various states of motion outside the Schwarzschild horizon is analyzed in the near-horizon limit, where the spatial curvature may be ignored and the metric may be approximated by that of Rindler. This analysis elucidates the influence of the horizon on the shapes and motions of electric and magnetic field lines when external agents move the field lines in arbitrary manners. It also illustrates how the field lines interact with the horizon's charge and current to produce an exchange of energy and momentum between the external agent and the horizon. A numerical calculation of the dynamical relaxation of a magnetic field threading a Schwarzschild black hole is also presented, illustrating the ''cleaning'' of a complicated field structure by a black-hole horizon, and elucidating the constraints on the location of the stretched horizon

  10. Membrane-Assisted Growth of DNA Origami Nanostructure Arrays

    Science.gov (United States)

    2015-01-01

    Biological membranes fulfill many important tasks within living organisms. In addition to separating cellular volumes, membranes confine the space available to membrane-associated proteins to two dimensions (2D), which greatly increases their probability to interact with each other and assemble into multiprotein complexes. We here employed two DNA origami structures functionalized with cholesterol moieties as membrane anchors—a three-layered rectangular block and a Y-shaped DNA structure—to mimic membrane-assisted assembly into hierarchical superstructures on supported lipid bilayers and small unilamellar vesicles. As designed, the DNA constructs adhered to the lipid bilayers mediated by the cholesterol anchors and diffused freely in 2D with diffusion coefficients depending on their size and number of cholesterol modifications. Different sets of multimerization oligonucleotides added to bilayer-bound origami block structures induced the growth of either linear polymers or two-dimensional lattices on the membrane. Y-shaped DNA origami structures associated into triskelion homotrimers and further assembled into weakly ordered arrays of hexagons and pentagons, which resembled the geometry of clathrin-coated pits. Our results demonstrate the potential to realize artificial self-assembling systems that mimic the hierarchical formation of polyhedral lattices on cytoplasmic membranes. PMID:25734977

  11. Membrane-assisted growth of DNA origami nanostructure arrays.

    Science.gov (United States)

    Kocabey, Samet; Kempter, Susanne; List, Jonathan; Xing, Yongzheng; Bae, Wooli; Schiffels, Daniel; Shih, William M; Simmel, Friedrich C; Liedl, Tim

    2015-01-01

    Biological membranes fulfill many important tasks within living organisms. In addition to separating cellular volumes, membranes confine the space available to membrane-associated proteins to two dimensions (2D), which greatly increases their probability to interact with each other and assemble into multiprotein complexes. We here employed two DNA origami structures functionalized with cholesterol moieties as membrane anchors--a three-layered rectangular block and a Y-shaped DNA structure--to mimic membrane-assisted assembly into hierarchical superstructures on supported lipid bilayers and small unilamellar vesicles. As designed, the DNA constructs adhered to the lipid bilayers mediated by the cholesterol anchors and diffused freely in 2D with diffusion coefficients depending on their size and number of cholesterol modifications. Different sets of multimerization oligonucleotides added to bilayer-bound origami block structures induced the growth of either linear polymers or two-dimensional lattices on the membrane. Y-shaped DNA origami structures associated into triskelion homotrimers and further assembled into weakly ordered arrays of hexagons and pentagons, which resembled the geometry of clathrin-coated pits. Our results demonstrate the potential to realize artificial self-assembling systems that mimic the hierarchical formation of polyhedral lattices on cytoplasmic membranes.

  12. Supermassive Black Hole Binaries: Multi-Messenger Astrophysics and Long Baselines with the Next-Generation Very Large Array

    Science.gov (United States)

    Burke-Spolaor, Sarah; Lazio, Joseph; Nyland, Kristina; Blecha, Laura; Bogdanovic, Tamara; Comerford, Julie; Liu, Xin; Taylor, Gregory; Shen, Yue; Maccarone, T. J.; Chomiuk, Laura; Reines, Amy

    2018-01-01

    Dual ( physical processes that drive both the remnant's dynamics and the inspiral of the black hole pair. A systematic census of the dual supermassive black hole population will also directly constrain the strength and distribution of objects emitting gravitational waves that will be detected by pulsar timing arrays and future space-based laser interferometers. Although the population of dual supermassive black holes in galaxy merger products is central to these topics and others, few have yet been discovered.A suite of radio, visible-infrared, and X-ray telescopes have just begun to reveal the population of kiloparsec-separation dual active nuclei. This poster will present the unique capability of radio observations to explore the dual and binary population of supermassive black hole binaries, and will highlight the observational techniques and discoveries expected for the Next-Generation Very Large Array.Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The NANOGrav project receives support from NSF Physics Frontier Center award number 1430284.

  13. Ratchet Effects and Domain Wall Energy Landscapes in Amorphous Magnetic Films with 2D Arrays of Asymmetric Holes

    Science.gov (United States)

    Martin, J. I.; Alija, A.; Sobrado, I.; Perez-Junquera, A.; Rodriguez-Rodriguez, G.; Velez, M.; Alameda, J. M.; Marconi, V. I.; Kolton, A. B.; Parrondo, J. M. R.

    2009-03-01

    The driven motion of domain walls in extended magnetic films patterned with 2D arrays of asymmetric holes has been found to be subject to two different crossed ratchet effects [1] which results in an inversion of the sign of domain wall motion rectification as a function of the applied magnetic field. This effect can be understood in terms of the competition between drive, elasticity and asymmetric pinning as revealed by a simple 4̂-model. In order to optimize the asymmetric hole design, the relevant energy landscapes for domain wall motion across the array of asymmetric holes have been calculated by micromagnetic simulations as a function of array geometrical characteristics. The effects of a transverse magnetic field on these two crossed ratchet effects will also be discussed in terms of the decrease in domain wall energy per unit area and of the modifications in the magnetostatic barriers for domain wall pinning at the asymmetric inclusions. Work supported by Spanish MICINN.[1] A. Perez-Junquera et al, Phys. Rev. Lett. 100 (2008) 037203

  14. Arrays of membrane isolated yttrium-barium-copper-oxide kinetic inductance bolometers

    International Nuclear Information System (INIS)

    Lindeman, M. A.; Bonetti, J. A.; Bumble, B.; Day, P. K.; Holmes, W. A.; Kleinsasser, A. W.; Eom, B. H.

    2014-01-01

    We are developing of arrays of membrane isolated resonator-bolometers, each with a kinetic inductance device (KID) to measure the temperature of the membrane. The KIDs are fabricated out of the high temperature superconductor YBCO to allow operation at relatively high temperatures. The bolometers are designed to offer higher sensitivity than sensors operating at 300 K, but they require less expensive and lighter weight cooling than even more sensitive conventional superconducting detectors operating at lower temperatures. The bolometer arrays are applicable as focal planes in infrared imaging spectrometers, such as for planetary science missions or earth observing satellites. We describe the devices and present measurements of their sensitivity.

  15. Arrays of membrane isolated yttrium-barium-copper-oxide kinetic inductance bolometers

    Energy Technology Data Exchange (ETDEWEB)

    Lindeman, M. A., E-mail: mark.a.lindeman@jpl.nasa.gov; Bonetti, J. A.; Bumble, B.; Day, P. K.; Holmes, W. A.; Kleinsasser, A. W. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Eom, B. H. [California Institute of Technology, Pasadena, California 91125 (United States)

    2014-06-21

    We are developing of arrays of membrane isolated resonator-bolometers, each with a kinetic inductance device (KID) to measure the temperature of the membrane. The KIDs are fabricated out of the high temperature superconductor YBCO to allow operation at relatively high temperatures. The bolometers are designed to offer higher sensitivity than sensors operating at 300 K, but they require less expensive and lighter weight cooling than even more sensitive conventional superconducting detectors operating at lower temperatures. The bolometer arrays are applicable as focal planes in infrared imaging spectrometers, such as for planetary science missions or earth observing satellites. We describe the devices and present measurements of their sensitivity.

  16. Assessing the efficacy of vesicle fusion with planar membrane arrays using a mitochondrial porin as reporter

    DEFF Research Database (Denmark)

    Pszon-Bartosz, Kamila Justyna; Hansen, Jesper S.; Stibius, Karin B.

    2011-01-01

    Reconstitution of functionally active membrane protein into artificially made lipid bilayers is a challenge that must be overcome to create a membrane-based biomimetic sensor and separation device. In this study we address the efficacy of proteoliposome fusion with planar membrane arrays. We...... establish a protein incorporation efficacy assay using the major non-specific porin of Fusobacterium nucleatum (FomA) as reporter. We use electrical conductance measurements and fluorescence microscopy to characterize proteoliposome fusion with an array of planar membranes. We show that protein...... reconstitution in biomimetic membrane arrays may be quantified using the developed FomA assay. Specifically, we show that FomA vesicles are inherently fusigenic. Optimal FomA incorporation is obtained with a proteoliposome lipid-to-protein molar ratio (LPR)=50 more than 105 FomA proteins could be incorporated...

  17. The Effect of Scala Tympani Morphology on Basilar Membrane Contact With a Straight Electrode Array: A Human Temporal Bone Study.

    Science.gov (United States)

    Verberne, Juul; Risi, Frank; Campbell, Luke; Chambers, Scott; O'Leary, Stephen

    2017-01-01

    Scala tympani morphology influences the insertion dynamics and intra-scalar position of straight electrode arrays. Hearing preservation is the goal of cochlear implantation with current thin straight electrode arrays. These hug the lateral wall, facilitating full, atraumatic insertions. However, most studies still report some postoperative hearing loss. This study explores the influence of scala tympani morphology on array position relative to the basilar membrane and its possible contribution to postoperative hearing loss. Twenty-six fresh-frozen human temporal bones implanted with a straight electrode array were three-dimensionally reconstructed from micro-photographic histological sections. Insertion depth and the proximity between the array and basilar membrane were recorded. Lateral wall shape was quantified as a curvature ratio. Insertion depths ranged from 233 to 470 degrees. The mean first point of contact between the array and basilar membrane was 185 degrees; arrays tended to remain in contact with the membrane after first contacting it. Eighty-nine and 93% of arrays that reached the upper basal (>240-360 degrees) and second (>360-720 degrees) turns respectively contacted the basilar membrane in these regions. Scalar wall curvature ratio decreased significantly (the wall became steeper) from the basal to second turns. This shift correlated with a reduced distance between the array and basilar membrane. Scala tympani morphology influences the insertion dynamics and intra-scalar position of a straight electrode array. In addition to gross trauma of cochlear structures, contact between the array and basilar membrane and how this impacts membrane function should be considered in hearing preservation cases.

  18. Silicon-on-insulator based nanopore cavity arrays for lipid membrane investigation.

    Science.gov (United States)

    Buchholz, K; Tinazli, A; Kleefen, A; Dorfner, D; Pedone, D; Rant, U; Tampé, R; Abstreiter, G; Tornow, M

    2008-11-05

    We present the fabrication and characterization of nanopore microcavities for the investigation of transport processes in suspended lipid membranes. The cavities are situated below the surface of silicon-on-insulator (SOI) substrates. Single cavities and large area arrays were prepared using high resolution electron-beam lithography in combination with reactive ion etching (RIE) and wet chemical sacrificial underetching. The locally separated compartments have a circular shape and allow the enclosure of picoliter volume aqueous solutions. They are sealed at their top by a 250 nm thin Si membrane featuring pores with diameters from 2 µm down to 220 nm. The Si surface exhibits excellent smoothness and homogeneity as verified by AFM analysis. As biophysical test system we deposited lipid membranes by vesicle fusion, and demonstrated their fluid-like properties by fluorescence recovery after photobleaching. As clearly indicated by AFM measurements in aqueous buffer solution, intact lipid membranes successfully spanned the pores. The nanopore cavity arrays have potential applications in diagnostics and pharmaceutical research on transmembrane proteins.

  19. Enhancement of hole injection and electroluminescence by ordered Ag nanodot array on indium tin oxide anode in organic light emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Mi, E-mail: jmnano00@gmail.com, E-mail: Dockha@kist.re.kr [Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); School of Mechanical Systems Engineering, Kookmin University, Seoul 136-702 (Korea, Republic of); Mo Yoon, Dang; Kim, Miyoung [Korea Printed Electronics Center, Korea Electronics Technology Institute, Jeollabuk-do, 561-844 (Korea, Republic of); Kim, Chulki; Lee, Taikjin; Hun Kim, Jae; Lee, Seok; Woo, Deokha, E-mail: jmnano00@gmail.com, E-mail: Dockha@kist.re.kr [Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Lim, Si-Hyung [School of Mechanical Systems Engineering, Kookmin University, Seoul 136-702 (Korea, Republic of)

    2014-07-07

    We report the enhancement of hole injection and electroluminescence (EL) in an organic light emitting diode (OLED) with an ordered Ag nanodot array on indium-tin-oxide (ITO) anode. Until now, most researches have focused on the improved performance of OLEDs by plasmonic effects of metal nanoparticles due to the difficulty in fabricating metal nanodot arrays. A well-ordered Ag nanodot array is fabricated on the ITO anode of OLED using the nanoporous alumina as an evaporation mask. The OLED device with Ag nanodot arrays on the ITO anode shows higher current density and EL enhancement than the one without any nano-structure. These results suggest that the Ag nanodot array with the plasmonic effect has potential as one of attractive approaches to enhance the hole injection and EL in the application of the OLEDs.

  20. Assessing the efficacy of vesicle fusion with planar membrane arrays using a mitochondrial porin as reporter

    International Nuclear Information System (INIS)

    Pszon-Bartosz, Kamila; Hansen, Jesper S.; Stibius, Karin B.; Groth, Jesper S.; Emneus, Jenny; Geschke, Oliver; Helix-Nielsen, Claus

    2011-01-01

    Research highlights: → We have established a vesicle fusion efficacy assay based on the major non-specific porin of Fusobacterium nucleatum (FomA). → Maximal fusion obtained was almost 150,000 porin insertions during 20 min. → Incorporation can be either first order or exponential kinetics which has implications for establishing protein delivery to biomimetic membranes. -- Abstract: Reconstitution of functionally active membrane protein into artificially made lipid bilayers is a challenge that must be overcome to create a membrane-based biomimetic sensor and separation device. In this study we address the efficacy of proteoliposome fusion with planar membrane arrays. We establish a protein incorporation efficacy assay using the major non-specific porin of Fusobacterium nucleatum (FomA) as reporter. We use electrical conductance measurements and fluorescence microscopy to characterize proteoliposome fusion with an array of planar membranes. We show that protein reconstitution in biomimetic membrane arrays may be quantified using the developed FomA assay. Specifically, we show that FomA vesicles are inherently fusigenic. Optimal FomA incorporation is obtained with a proteoliposome lipid-to-protein molar ratio (LPR) = 50 more than 10 5 FomA proteins could be incorporated in a bilayer array with a total membrane area of 2 mm 2 within 20 min. This novel assay for quantifying protein delivery into lipid bilayers may be a useful tool in developing biomimetic membrane applications.

  1. Freestanding membrane composed of micro-ring array with ultrahigh sidewall aspect ratio for application in lightweight cathode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lanlan [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Liu, Hongzhong, E-mail: hzliu@mail.xjtu.edu.cn [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Jiang, Weitao, E-mail: wtjiang@mail.xjtu.edu.cn [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Gao, Wei [Key Laboratory of Mechanics on Western Disasters and Environment, Lanzhou University, Lanzhou 730000 (China); Chen, Bangdao [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Li, Xin [Department of Microelectronics, Xi’an Jiaotong University, Xi’an 710049 (China); Ding, Yucheng [State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); An, Ningli [Department of Packaging Engineering, Xi’an University of Technology, Xi’an 710048 (China)

    2014-12-15

    Graphical abstract: A freestanding multilayer ultrathin nano-membrane (FUN-membrane) with a micro-ring array (MRA), in which the dimension of each micro-ring is 3 μm in diameter, 2 μm in height and sub-100 nm in sidewall thickness is successfully fabricated, as shown in the SEM image of figure (a). Due to the MRA with ultrahigh aspect ratio of dielectric-metal sidewall, the FUN-membrane can be transferred to either rigid or flexible substrate to be used as the cathode for lightweight display panel, as shown in the schematic of figure (b). - Highlights: • Exploring a new fabrication method for the freestanding ultrathin nano-membrane (FUN-membrane). • FUN-membrane is composed of micro-ring array with ultrahigh aspect ratio of the insulator-metal sidewall. • The sharp metal edge of each micro-ring is preferred to be served as the micro-emitter. - Abstract: A freestanding multilayer ultrathin nano-membrane (FUN-membrane) with a micro-ring array (MRA) is successfully fabricated through the controllable film deposition. Each micro-ring of FUN-membrane is 3 μm in diameter, 2 μm in height and sub-100 nm in sidewall thickness, demonstrating an ultrahigh sidewall aspect ratio of 20:1. In our strategy, a silica layer (200 nm in thickness), a chromium transition layer (5 nm-thick) and a gold layer (40 nm-thick), were in sequence deposited on patterned photoresist. After removal of the photoresist by lift-off process, a FUN-membrane with MRA was peeled off from the substrate, where the gold layer acted as a protecting layer to prevent the MRA from fracture. The FUN-membrane was then transferred to a flexible polycarbonate (PC) sheet coated with indium tin oxide (ITO) layer, which was then used as a flexible and lightweight cathode. Remarkably, the field emission effect of the fabricated FUN-membrane cathode performs a high field-enhancement factor of 1.2 × 10{sup 4} and a low turn-on voltage of 2 V/μm, indicating the advantages of the sharp metal edge of MRA. Due

  2. Freestanding membrane composed of micro-ring array with ultrahigh sidewall aspect ratio for application in lightweight cathode arrays

    International Nuclear Information System (INIS)

    Wang, Lanlan; Liu, Hongzhong; Jiang, Weitao; Gao, Wei; Chen, Bangdao; Li, Xin; Ding, Yucheng; An, Ningli

    2014-01-01

    Graphical abstract: A freestanding multilayer ultrathin nano-membrane (FUN-membrane) with a micro-ring array (MRA), in which the dimension of each micro-ring is 3 μm in diameter, 2 μm in height and sub-100 nm in sidewall thickness is successfully fabricated, as shown in the SEM image of figure (a). Due to the MRA with ultrahigh aspect ratio of dielectric-metal sidewall, the FUN-membrane can be transferred to either rigid or flexible substrate to be used as the cathode for lightweight display panel, as shown in the schematic of figure (b). - Highlights: • Exploring a new fabrication method for the freestanding ultrathin nano-membrane (FUN-membrane). • FUN-membrane is composed of micro-ring array with ultrahigh aspect ratio of the insulator-metal sidewall. • The sharp metal edge of each micro-ring is preferred to be served as the micro-emitter. - Abstract: A freestanding multilayer ultrathin nano-membrane (FUN-membrane) with a micro-ring array (MRA) is successfully fabricated through the controllable film deposition. Each micro-ring of FUN-membrane is 3 μm in diameter, 2 μm in height and sub-100 nm in sidewall thickness, demonstrating an ultrahigh sidewall aspect ratio of 20:1. In our strategy, a silica layer (200 nm in thickness), a chromium transition layer (5 nm-thick) and a gold layer (40 nm-thick), were in sequence deposited on patterned photoresist. After removal of the photoresist by lift-off process, a FUN-membrane with MRA was peeled off from the substrate, where the gold layer acted as a protecting layer to prevent the MRA from fracture. The FUN-membrane was then transferred to a flexible polycarbonate (PC) sheet coated with indium tin oxide (ITO) layer, which was then used as a flexible and lightweight cathode. Remarkably, the field emission effect of the fabricated FUN-membrane cathode performs a high field-enhancement factor of 1.2 × 10 4 and a low turn-on voltage of 2 V/μm, indicating the advantages of the sharp metal edge of MRA. Due to the

  3. Nanopillar arrays on semiconductor membranes as electron emission amplifiers.

    Science.gov (United States)

    Qin, Hua; Kim, Hyun-Seok; Blick, Robert H

    2008-03-05

    A new transmission-type electron multiplier was fabricated from silicon-on-insulator (SOI) material by integrating an array of one-dimensional (1D) silicon nanopillars onto a two-dimensional (2D) silicon membrane. Primary electrons are injected into the nanopillar-membrane (NPM) system from the flat surface of the membrane, while electron emission from the nanopillars is probed by an anode. The secondary electron yield (SEY) from the nanopillars in the current device is found to be about 1.8 times that of the plain silicon membrane. This gain in electron number is slightly enhanced by the electric field applied from the anode. Further optimization of the dimensions of the NPM and an application of field emission promise an even higher gain for detector applications and allow for probing of electronic/mechanical excitations in an NPM system stimulated by incident particles or radiation.

  4. Gradient index metamaterials realized by drilling hole arrays

    International Nuclear Information System (INIS)

    Mei Zhonglei; Cui Tiejun; Bai Jing

    2010-01-01

    Gradient index metamaterials have wide applications in the microwave and optical fields. Based on the quasi-static theory, such materials at the microwave band have been realized by drilling hole arrays on ordinary dielectric materials. As applications of the gradient index metamaterials, novel devices including a 45 0 dielectric wave-bending structure, a 16 0 wave-steering lens and a microwave focusing lens are designed and fabricated. Field mapping measurements validate the proposed gradient index metamaterials and the device designs. The method can be directly and easily extended to the design of cloaks, various lenses, beam shifters and beam-steering devices. It can also be applied in the optical band as long as quasi-static conditions are satisfied. The method and the devices may find applications in integrated circuit systems.

  5. Nanopore arrays in a silicon membrane for parallel single-molecule detection: fabrication

    Science.gov (United States)

    Schmidt, Torsten; Zhang, Miao; Sychugov, Ilya; Roxhed, Niclas; Linnros, Jan

    2015-08-01

    Solid state nanopores enable translocation and detection of single bio-molecules such as DNA in buffer solutions. Here, sub-10 nm nanopore arrays in silicon membranes were fabricated by using electron-beam lithography to define etch pits and by using a subsequent electrochemical etching step. This approach effectively decouples positioning of the pores and the control of their size, where the pore size essentially results from the anodizing current and time in the etching cell. Nanopores with diameters as small as 7 nm, fully penetrating 300 nm thick membranes, were obtained. The presented fabrication scheme to form large arrays of nanopores is attractive for parallel bio-molecule sensing and DNA sequencing using optical techniques. In particular the signal-to-noise ratio is improved compared to other alternatives such as nitride membranes suffering from a high-luminescence background.

  6. Cell membrane conformation at vertical nanowire array interface revealed by fluorescence imaging

    International Nuclear Information System (INIS)

    Berthing, Trine; Bonde, Sara; Rostgaard, Katrine R; Martinez, Karen L; Madsen, Morten Hannibal; Sørensen, Claus B; Nygård, Jesper

    2012-01-01

    The perspectives offered by vertical arrays of nanowires for biosensing applications in living cells depend on the access of individual nanowires to the cell interior. Recent results on electrical access and molecular delivery suggest that direct access is not always obtained. Here, we present a generic approach to directly visualize the membrane conformation of living cells interfaced with nanowire arrays, with single nanowire resolution. The method combines confocal z-stack imaging with an optimized cell membrane labelling strategy which was applied to HEK293 cells interfaced with 2–11 μm long and 3–7 μm spaced nanowires with various surface coatings (bare, aminosilane-coated or polyethyleneimine-coated indium arsenide). We demonstrate that, for all commonly used nanowire lengths, spacings and surface coatings, nanowires generally remain enclosed in a membrane compartment, and are thereby not in direct contact with the cell interior. (paper)

  7. Multichannel Discriminative Detection of Explosive Vapors with an Array of Nanofibrous Membranes Loaded with Quantum Dots

    Directory of Open Access Journals (Sweden)

    Zhaofeng Wu

    2017-11-01

    Full Text Available The multichannel fluorescent sensor array based on nanofibrous membranes loaded with ZnS quantum dots (QDs was created and demonstrated for the discriminative detection of explosives. The synergistic effect of the high surface-to-volume ratio of QDs, the good permeability of nanofibrous membranes and the differential response introduced by surface ligands was played by constructing the sensing array using nanofibrous membranes loaded with ZnS QDs featuring several surface ligands. Interestingly, although the fluorescence quenching of the nanofibrous membranes is not linearly related to the exposure time, the fingerprint of each explosive at different times is very similar in shape, and the fingerprints of the three explosives show different shapes. Three saturated vapors of nitroaromatic explosives could be reliably detected and discriminated by the array at room temperature. This work is the first step toward devising a monitoring system for explosives in the field of public security and defense. It could, for example, be coupled with the technology of image recognition and large data analysis for a rapid diagnostic test of explosives. This work further highlights the power of differential, multichannel arrays for the rapid and discriminative detection of a wide range of chemicals.

  8. Erythrocyte swelling and membrane hole formation in hypotonic media as studied by conductometry.

    Science.gov (United States)

    Pribush, A; Meyerstein, D; Hatskelzon, L; Kozlov, V; Levi, I; Meyerstein, N

    2013-02-01

    Hypoosmotic swelling of erythrocytes and the formation of membrane holes were studied by measuring the dc conductance (G). In accordance with the theoretical predictions, these processes are manifested by a decrease in G followed by its increase. Thus, unlike the conventional osmotic fragility test, the proposed methodological approach allows investigations of both the kinetics of swelling and the erythrocyte fragility. It is shown that the initial rate of swelling and the equilibrium size of the cells are affected by the tonicity of a hypotonic solution and the membrane rheological properties. Because the rupture of biological membranes is a stochastic process, a time-dependent increase in the conductance follows an integral distribution function of the membrane lifetime. The main conclusion which stems from reported results is that information about rheological properties of red blood cell (RBC) membranes and the resistivity of RBCs to a certain osmotic shock may be extracted from conductance signals.

  9. INTERNAL LIMITING MEMBRANE PEELING IN MACULAR HOLE SURGERY; WHY, WHEN, AND HOW?

    Science.gov (United States)

    Chatziralli, Irini P; Theodossiadis, Panagiotis G; Steel, David H W

    2018-05-01

    To review the current rationale for internal limiting membrane (ILM) peeling in macular hole (MH) surgery and to discuss the evidence base behind why, when, and how surgeons peel the ILM. Review of the current literature. Pars plana vitrectomy is an effective treatment for idiopathic MH, and peeling of the ILM has been shown to improve closure rates and to prevent postoperative reopening. However, some authors argue against ILM peeling because it results in a number of changes in retinal structure and function and may not be necessary in all cases. Furthermore, the extent of ILM peeling optimally performed and the most favorable techniques to remove the ILM are uncertain. Several technique variations including ILM flaps, ILM scraping, and foveal sparing ILM peeling have been described as alternatives to conventional peeling in specific clinical scenarios. Internal limiting membrane peeling improves MH closure rates but can have several consequences on retinal structure and function. Adjuvants to aid peeling, instrumentation, technique, and experience may all alter the outcome. Hole size and other variables are important in assessing the requirement for peeling and potentially its extent. A variety of evolving alternatives to conventional peeling may improve outcomes and need further study.

  10. Acoustic transmission resonance and suppression through double-layer subwavelength hole arrays

    International Nuclear Information System (INIS)

    Liu Zhifeng; Jin Guojun

    2010-01-01

    We present a theoretical study of acoustic waves passing through double-layer subwavelength hole arrays. The acoustic transmission resonance and suppression are observed. There are three mechanisms responsible for the transmission resonance: the excitation of geometrically induced acoustic surface waves, the Fabry-Perot resonance in a hole cavity (I-FP resonance) and the Fabry-Perot resonance between two plates (II-FP resonance). We can differentiate these mechanisms via the dispersion relation of acoustic modes supported by the double-layer structure. It is confirmed that the coupling between two single-layer perforated plates, associated with longitudinal interval and lateral displacement, plays a crucial role in modulating the transmission properties. The strong coupling between two plates can induce the splitting of the transmission peak, while the decoupling between plates leads to the appearance of transmission suppression. By analyzing the criterion derived for transmission suppression, we conclude that it is the destructive interference between the diffracted waves and the direct transmission waves assisted by the I-FP resonance of the first plate that leads to the decoupling between plates and then the transmission suppression.

  11. Polycarbonate-based ordered arrays of electrochemical nanoelectrodes obtained by e-beam lithography

    Energy Technology Data Exchange (ETDEWEB)

    Moretto, L M; De Leo, M; Ugo, P [Department of Molecular Sciences and Nanosystems, University Ca' Foscari of Venice, Santa Marta 2137, 30123 Venice (Italy); Tormen, M; Carpentiero, A, E-mail: ugo@unive.it [CNR-IOM, TASC Laboratory, Basovizza S S 14 km 163.5, 34149 Trieste (Italy)

    2011-05-06

    Ordered arrays of nanoelectrodes for electrochemical use are prepared by electron beam lithography (EBL) using polycarbonate as a novel e-beam resist. The nanoelectrodes are fabricated by patterning arrays of holes in a thin film of polycarbonate spin-coated on a gold layer on Si/Si{sub 3}N{sub 4} substrate. Experimental parameters for the successful use of polycarbonate as high resolution EBL resist are optimized. The holes can be filled partially or completely by electrochemical deposition of gold. This enables the preparation of arrays of nanoelectrodes with different recession degree and geometrical characteristics. The polycarbonate is kept on-site and used as the insulator that separates the nanoelectrodes. The obtained nanoelectrode arrays (NEAs) exhibit steady state current controlled by pure radial diffusion in cyclic voltammetry for scan rates up to approximately 50 mV s{sup -1}. Electrochemical results showed satisfactory agreement between experimental voltammograms and suitable theoretical models. Finally, the peculiarities of NEAs versus ensembles of nanoelectrodes, obtained by membrane template synthesis, are critically evaluated.

  12. Ferromagnetic resonance investigation in permalloy magnetic antidot arrays on alumina nanoporous membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Suárez, R.L., E-mail: rrodriguez@fis.puc.cl [Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860 Casilla 306, Santiago (Chile); Palma, J.L.; Burgos, E.O. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Michea, S. [Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860 Casilla 306, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Escrig, J.; Denardin, J.C. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Aliaga, C. [Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago (Chile)

    2014-01-15

    The magnetic properties of Ni{sub 80}Fe{sub 20} antidot arrays with hole diameters of 18 and 70 nm fabricated by a template-assisted method were investigated using the ferromagnetic resonance technique. Tuning the antidot arrays by changing the hole diameter enables control on the angular dependence of the ferromagnetic resonance field. The scanning electron microscope images reveal a quite regular hexagonal arrangement of the pores, however the angular dependence of the resonance field do not exhibit the six-fold symmetry expected for this symmetry. Micromagnetic simulations performed on a perfect hexagonal lattice, when compared with those made on our real system taken from the scanning microscope images, reveal that the presence of defects in the antidot lattice affects the ferromagnetic resonance field symmetry. - Highlights: • We use the FMR technique to investigate the magnetic properties of Py antidots. • We studied the effect of pore diameter on FMR angular measurement. • FMR field does not exhibit the six-fold symmetry. • For all angular positions there are two resonance modes always present. • Micromagnetic simulations agree with the experimental results with defects.

  13. Atomic force microscopy for cellular level manipulation: imaging intracellular structures and DNA delivery through a membrane hole.

    Science.gov (United States)

    Afrin, Rehana; Zohora, Umme Salma; Uehara, Hironori; Watanabe-Nakayama, Takahiro; Ikai, Atsushi

    2009-01-01

    The atomic force microscope (AFM) is a versatile tool for imaging, force measurement and manipulation of proteins, DNA, and living cells basically at the single molecular level. In the cellular level manipulation, extraction, and identification of mRNA's from defined loci of a cell, insertion of plasmid DNA and pulling of membrane proteins, for example, have been reported. In this study, AFM was used to create holes at defined loci on the cell membrane for the investigation of viability of the cells after hole creation, visualization of intracellular structure through the hole and for targeted gene delivery into living cells. To create large holes with an approximate diameter of 5-10 microm, a phospholipase A(2) coated bead was added to the AFM cantilever and the bead was allowed to touch the cell surface for approximately 5-10 min. The evidence of hole creation was obtained mainly from fluorescent image of Vybrant DiO labeled cell before and after the contact with the bead and the AFM imaging of the contact area. In parallel, cells with a hole were imaged by AFM to reveal intracellular structures such as filamentous structures presumably actin fibers and mitochondria which were identified with fluorescent labeling with rhodamine 123. Targeted gene delivery was also attempted by inserting an AFM probe that was coated with the Monster Green Fluorescent Protein phMGFP Vector for transfection of the cell. Following targeted transfection, the gene expression of green fluorescent protein (GFP) was observed and confirmed by the fluorescence microscope. Copyright (c) 2009 John Wiley & Sons, Ltd.

  14. Plasmonic nanoantenna arrays for surface-enhanced Raman spectroscopy of lipid molecules embedded in a bilayer membrane.

    Science.gov (United States)

    Kühler, Paul; Weber, Max; Lohmüller, Theobald

    2014-06-25

    We demonstrate a strategy for surface-enhanced Raman spectroscopy (SERS) of supported lipid membranes with arrays of plasmonic nanoantennas. Colloidal lithography refined with plasma etching is used to synthesize arrays of triangular shaped gold nanoparticles. Reducing the separation distance between the triangle tips leads to plasmonic coupling and to a strong enhancement of the electromagnetic field in the nanotriangle gap. As a result, the Raman scattering intensity of molecules that are located at this plasmonic "hot-spot" can be increased by several orders of magnitude. The nanoantenna array is then embedded with a supported phospholipid membrane which is fluid at room temperature and spans the antenna gap. This configuration offers the advantage that molecules that are mobile within the bilayer membrane can enter the "hot-spot" region via diffusion and can therefore be measured by SERS without static entrapment or adsorption of the molecules to the antenna itself.

  15. Clinical and histological evaluation of large macular hole surgery using the inverted internal limiting membrane flap technique

    Directory of Open Access Journals (Sweden)

    Kase S

    2016-12-01

    Full Text Available Satoru Kase, Wataru Saito, Shohei Mori, Michiyuki Saito, Ryo Ando, Zhenyu Dong, Tomohiro Suzuki, Kousuke Noda, Susumu Ishida Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan Purpose: The aims of this study were to analyze optical coherence tomography (OCT imaging of large macular holes (MHs treated with inverted internal limiting membrane (ILM flap technique and to perform a histological examination of an ILM-like membrane tissue obtained during vitrectomy.Patients and methods: This is a retrospective observational case study. Nine patients, comprising of five males and four females, showing large and myopic MHs, underwent pars plana vitrectomy (PPV with inverted ILM flap technique assisted by brilliant blue G (BBG staining. Ophthalmological findings including visual acuity and OCT were investigated based on medical records. Formalin-fixed paraffin-embedded tissue section of an ILM-like membrane was submitted for immunohistochemistry with glial fibrillary acidic protein (GFAP.Results: ILM was clearly stained with BBG in eight patients, whereas the ILM in one case revealed no staining with BBG during PPV. Visual acuities improved to >0.2 LogMAR in six patients. The complete closure of MH following PPV with inverted ILM technique was eventually achieved in all patients determined by OCT imaging (100%. Only one patient showed recovery of ellipsoid zone and interdigitation zone following the surgery. Elongation of outer nuclear layer was noted in three eyes. The ILM-like membrane not stained with BBG histologically revealed an amorphous structure admixed with GFAP-positive mononuclear cell infiltration.Conclusion: PPV with inverted ILM flap technique achieved 100% closure rates with favorable configuration at an initial surgery in large MHs. Our histopathological data also suggest that even BBG staining-negative membrane may be a useful material for autologous transplantation to the hole. Keywords

  16. [Long-term outcome of vitrectomy combined with internal limiting membrane peeling for idiopathic macular holes].

    Science.gov (United States)

    Yamamoto, Kaori; Hori, Sadao

    2011-01-01

    To elucidate the long-term outcome of internal limiting membrane (ILM) peeling on visual function during vitrectomy for idiopathic macular holes using scanning laser ophthalmoscope (SLO) microperimetry. Prospective uncontrolled study. We studied 31 eyes (29 patients) with idiopathic macular holes. All patients underwent vitrectomy with ILM peeling. The SLO microperimetry was performed preoperatively, and once a year for 3 years postoperatively to detect scotomas in and around the macular holes, and both within and in close vicinity to the areas of ILM peeling. Closure of macular holes after one surgery was confirmed in all cases except for 2 with second surgery. The visual acuity by logarithmic minimum angle of resolution (logMAR) averaged 0.71 +/- 0.36 before surgery, 0.23 +/- 0.31 one year, 0.14 +/- 0.27 two years and 0.12 +/- 0.26 three years after surgery. There was significant improvement up to 2 years after the surgery. All scotomas detected before surgery in the holes, and 77.4% of those detected around the holes decreased gradually. No scotomas were detected in or around the area of ILM peeling either before or after surgery. ILM peeling in vitrectomy for idiopathic macular holes successfully improved visual acuity and did not influence retinal sensitivity in and around the area of ILM peeling. The scotomas detected in and around the holes before surgery gradually reduced or disappeared.

  17. Using a Semiconductor-to-Metal Transition to Control Optical Transmission through Subwavelength Hole Arrays

    Directory of Open Access Journals (Sweden)

    E. U. Donev

    2008-01-01

    Full Text Available We describe a simple configuration in which the extraordinary optical transmission effect through subwavelength hole arrays in noble-metal films can be switched by the semiconductor-to-metal transition in an underlying thin film of vanadium dioxide. In these experiments, the transition is brought about by thermal heating of the bilayer film. The surprising reverse hysteretic behavior of the transmission through the subwavelength holes in the vanadium oxide suggest that this modulation is accomplished by a dielectric-matching condition rather than plasmon coupling through the bilayer film. The results of this switching, including the wavelength dependence, are qualitatively reproduced by a transfer matrix model. The prospects for effecting a similar modulation on a much faster time scale by using ultrafast laser pulses to trigger the semiconductor-to-metal transition are also discussed.

  18. Membrane paradigm

    International Nuclear Information System (INIS)

    Price, R.H.; Thorne, K.S.

    1986-01-01

    The membrane paradigm is a modified frozen star approach to modeling black holes, with particles and fields assuming a complex, static, boundary-layer type structure (membrane) near the event horizon. The membrane has no effects on the present or future evolution of particles and fields above itself. The mathematical representation is a combination of a formalism containing terms for the shear and bulk viscosity, surface pressure, momentum, temperature, entropy, etc., of the horizon and the 3+1 formalism. The latter model considers a family of three-dimensional spacelike hypersurfaces in one-dimensional time. The membrane model considers a magnetic field threading the hole and undergoing torque from the hole rotation. The field is cleaned by the horizon and distributed over the horizon so that ohmic dissipation is minimized. The membrane paradigm is invalid inside the horizon, but is useful for theoretically probing the properties of slowly evolving black holes

  19. IMPACT OF INTERNAL LIMITING MEMBRANE PEELING ON MACULAR HOLE REOPENING: A Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Rahimy, Ehsan; McCannel, Colin A

    2016-04-01

    To assess the literature regarding macular hole reopening rates stratified by whether the internal limiting membrane (ILM) was peeled during vitrectomy surgery. Systematic review and meta-analysis of studies reporting on macular hole reopenings among previously surgically closed idiopathic macular holes. A comprehensive literature search using the National Library of Medicine PubMed interface was used to identify potentially eligible publications in English. The minimum mean follow-up period for reports to be included in this study was 12 months. Analysis was divided into eyes that underwent vitrectomy with and without ILM peeling. The primary outcome parameter was the proportion of macular hole reopenings among previously closed holes between the two groups. Secondary outcome parameters included duration from initial surgery to hole reopening and preoperative and postoperative best-corrected correct visual acuities among the non-ILM peeling and ILM peeling groups. A total of 50 publications reporting on 5,480 eyes met inclusion criteria and were assessed in this meta-analysis. The reopening rate without ILM peeling was 7.12% (125 of 1,756 eyes), compared with 1.18% (44 of 3,724 eyes) with ILM peeling (odds ratio: 0.16; 95% confidence interval: 0.11-0.22; Fisher's exact test: P peeling during macular hole surgery reduces the likelihood of macular hole reopening.

  20. Macular morphology and visual acuity after macular hole surgery with or without internal limiting membrane peeling

    DEFF Research Database (Denmark)

    Christensen, U.C.; Kroyer, K.; Sander, B.

    2010-01-01

    Aim: To examine postoperative macular morphology and visual outcome after 12 months in relation to internal limiting membrane (ILM) peeling versus no peeling, indocyanine green (ICG) staining and re-operation in eyes that achieved macular hole closure after surgery. Methods: Seventy-four eyes...... with closed stage 2 or 3 macular holes were recruited from a randomised clinical trial comparing: (1) vitrectomy without ILM peeling; (2) vitrectomy with 0.05% isotonic ICG-assisted ILM peeling; and (3) vitrectomy with 0.15% trypan blue-assisted ILM peeling. Contrast-enhanced Stratus optical coherence...... between subgroups. Conclusions: Poor vision after 12 months despite macular hole closure was associated with attenuation and disruption of the foveolar photoreceptor matrix. The extent of attenuation and disruption was independent of peeling and staining....

  1. Photoreceptor Outer Segment on Internal Limiting Membrane after Macular Hole Surgery: Implications for Pathogenesis.

    Science.gov (United States)

    Grinton, Michael E; Sandinha, Maria T; Steel, David H W

    2015-01-01

    This report presents a case, which highlights key principles in the pathophysiology of macular holes. It has been hypothesized that anteroposterior (AP) and tangential vitreous traction on the fovea are the primary underlying factors causing macular holes [Nischal and Pearson; in Kanski and Bowling: Clinical Ophthalmology: A Systemic Approach, 2011, pp 629-631]. Spectral domain optical coherence tomography (OCT) has subsequently corroborated this theory in part but shown that AP vitreofoveal traction is the more common scenario [Steel and Lotery: Eye 2013;27:1-21]. This study was conducted as a single case report. A 63-year old female presented to her optician with blurred and distorted vision in her left eye. OCT showed a macular hole with a minimum linear diameter of 370 µm, with persistent broad vitreofoveal attachment on both sides of the hole edges. The patient underwent combined left phacoemulsification and pars plana vitrectomy, internal limiting membrane (ILM) peel and gas injection. The ILM was examined by electron microscopy and showed the presence of a cone outer segment on the retinal side. Post-operative OCT at 11 weeks showed a closed hole with recovery of the foveal contour and good vision. Our case shows the presence of a photoreceptor outer segment on the retinal side of the ILM and reinforces the importance of tangential traction in the development of some macula holes. The case highlights the theory of transmission of inner retinal forces to the photoreceptors via Müller cells and how a full thickness macular hole defect can occur in the absence of AP vitreomacular traction.

  2. Vitrectomy with internal limiting membrane peeling for macular hole in high myopia eyes

    Directory of Open Access Journals (Sweden)

    Chun-Mei Deng

    2015-08-01

    Full Text Available AIM: To compare the clinical effects between pars plana vitrectomy(PPVand PPV with internal limiting membrane peeling(ILMPfor macular hole in high myopia eyes. METHODS:The clinical data of 33 high myopia with macular hole patients(36 eyeswith or without retinal detachment caused by macular hole were retrospectively analyzed. The patients were divided into two groups according to different operation methods: 15 eyes in groupⅠhad undergone PPV; 21 eyes in groupⅡhad undergone PPV with ILMPP peeling. According to different conditions of patients,different auxiliary methods were accepted, such as silicone oil tamponade, C3F8 tamponade, photocoagulation, condensation, etc. The follow-up period was 3~12mo. Best corrected visual acuity(BCVA, macular hole closure rate and retinal reattachment rate were continuous checked after operation. Then we evaluated the outcome in the two groups by statistical analysis.RESULTS: The postoperative mean BCVA increased by 0.167 in group Ⅰand 0.456 in group Ⅱ than preoperative, the difference was significant(t=2.46,6.753; P=0.027,0.000. And the difference of BCVA improvement was significant between those two groups(t=-2.943, P=0.006. The macular hole closed in 7 eyes(46.67%in group Ⅰ,and 18 eyes(85.71%in group Ⅱ; The difference was significant between those two groups(χ2=6.287,P=0.025.Retinal reattachment was found in 11 eyes(91.67%in group Ⅰ and 19 eyes(94.73%in group Ⅱ. The difference was not significant between the two groups(χ2=0.856, P=0.418. CONCLUSION: PPV with ILMPP peeling for macular hole in high myopia eyes can obviously improve closure of macular hole and postoperative visual acuity. But the difference of retinal reattachment rate was not significant between peeling and unpeeling of ILMP.

  3. Black hole dynamics at large D

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    We demonstrate that the classical dynamics of black holes can be reformulated as a dynamical problem of a codimension one membrane moving in flat space. This membrane - roughly the black hole event horizon - carries a conserved charge current and stress tensor which source radiation. This `membrane paradigm' may be viewed as a simplification of the equations of general relativity at large D, and suggests the possibility of using 1/D as a useful expansion parameter in the analysis of complicated four dimensional solutions of general relativity, for instance the collision between two black holes.

  4. Vitrectomy with internal limiting membrane (ILM) peeling versus vitrectomy with no peeling for idiopathic full-thickness macular hole (FTMH)

    DEFF Research Database (Denmark)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil

    2013-01-01

    Several observational studies have suggested the potential benefit of internal limiting membrane (ILM) peeling to treat idiopathic full-thickness macular hole (FTMH). However, no strong evidence is available on the potential benefit(s) of this surgical manoeuvre and uncertainty remains among...... vitreoretinal surgeons about the indication for peeling the ILM, whether to use it in all cases or in long-standing and/or larger holes. ...

  5. Vitrectomy with internal limiting membrane peeling versus inverted internal limiting membrane flap technique for macular hole-induced retinal detachment: a systematic review of literature and meta-analysis.

    Science.gov (United States)

    Yuan, Jing; Zhang, Ling-Lin; Lu, Yu-Jie; Han, Meng-Yao; Yu, Ai-Hua; Cai, Xiao-Jun

    2017-11-28

    To evaluate the effects on vitrectomy with internal limiting membrane (ILM) peeling versus vitrectomy with inverted internal limiting membrane flap technique for macular hole-induced retinal detachment (MHRD). Pubmed, Cochrane Library, and Embase were systematically searched for studies that compared ILM peeling with inverted ILM flap technique for macular hole-induced retinal detachment. The primary outcomes are the rate of retinal reattachment and the rate of macular hole closure 6 months later after initial surgery, the secondary outcome is the postoperative best-corrected visual acuity (BCVA) 6 months later after initial surgery. Four studies that included 98 eyes were selected. All the included studies were retrospective comparative studies. The preoperative best-corrected visual acuity was equal between ILM peeling and inverted ILM flap technique groups. It was indicated that the rate of retinal reattachment (odds ratio (OR) = 0.14, 95% confidence interval (CI):0.03 to 0.69; P = 0.02) and macular hole closure (OR = 0.06, 95% CI:0.02 to 0.19; P peeling. However, there was no statistically significant difference in postoperative best-corrected visual acuity (mean difference (MD) 0.18 logarithm of the minimum angle of resolution; 95% CI -0.06 to 0.43 ; P = 0.14) between the two surgery groups. Compared with ILM peeling, vitrectomy with inverted ILM flap technique resulted significantly higher of the rate of retinal reattachment and macular hole closure, but seemed does not improve postoperative best-corrected visual acuity.

  6. Constraints on the Dynamical Environments of Supermassive Black-Hole Binaries Using Pulsar-Timing Arrays.

    Science.gov (United States)

    Taylor, Stephen R; Simon, Joseph; Sampson, Laura

    2017-05-05

    We introduce a technique for gravitational-wave analysis, where Gaussian process regression is used to emulate the strain spectrum of a stochastic background by training on population-synthesis simulations. This leads to direct Bayesian inference on astrophysical parameters. For pulsar timing arrays specifically, we interpolate over the parameter space of supermassive black-hole binary environments, including three-body stellar scattering, and evolving orbital eccentricity. We illustrate our approach on mock data, and assess the prospects for inference with data similar to the NANOGrav 9-yr data release.

  7. Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

    Science.gov (United States)

    Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

    2012-07-01

    The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm2) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

  8. Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

    International Nuclear Information System (INIS)

    Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

    2012-01-01

    The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm 2 ) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

  9. The effect of holes in the dispersion relation of propagative surface plasmon modes of nanoperforated semitransparent metallic films

    International Nuclear Information System (INIS)

    Kekesi, R.; Meneses-Rodríguez, D.; García-Pérez, F.; González, M. U.; García-Martín, A.; Cebollada, A.; Armelles, G.

    2014-01-01

    We have analysed the effect that holes have on the properties of propagative surface plasmon modes in semitransparent nanoperforated Au films. The modes have been excited in Kretschmann configuration. Contrary to continuous films, where only one mode is excited, two modes are observed in Au nanohole array. The origin of this different behavior is discussed using effective optical properties for the nanoperforated films. The presence of the holes affects the effective optical constants of the membranes in two ways: it changes the contribution of the free electrons, and it gives rise to a localized transition due to a hole induced plasmon resonance. This localized transition interacts with the propagative surface plasmon modes, originating the two detected modes.

  10. The effect of holes in the dispersion relation of propagative surface plasmon modes of nanoperforated semitransparent metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Kekesi, R., E-mail: renata.kekesi@csic.es; Meneses-Rodríguez, D.; García-Pérez, F.; González, M. U.; García-Martín, A.; Cebollada, A.; Armelles, G., E-mail: gaspar@imm.cnm.csic.es [IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC), Isaac Newton 8, PTM, E-28760 Tres Cantos, Madrid (Spain)

    2014-10-07

    We have analysed the effect that holes have on the properties of propagative surface plasmon modes in semitransparent nanoperforated Au films. The modes have been excited in Kretschmann configuration. Contrary to continuous films, where only one mode is excited, two modes are observed in Au nanohole array. The origin of this different behavior is discussed using effective optical properties for the nanoperforated films. The presence of the holes affects the effective optical constants of the membranes in two ways: it changes the contribution of the free electrons, and it gives rise to a localized transition due to a hole induced plasmon resonance. This localized transition interacts with the propagative surface plasmon modes, originating the two detected modes.

  11. High Density Silver Nanowire Arrays using Self-ordered Anodic Aluminum Oxide (AAO) Membrane

    OpenAIRE

    Han, Young-Hwan

    2008-01-01

    High density silver nanowire arrays were synthesized through the self-ordered Anodic Aluminum Oxide (AAO) template. The pore size in the AAO membrane was confirmed by processing the widening porosity with a honeycomb structure with cross sections of 20nm, 50nm, and 100nm, by SEM. Pore numbers by unit area were consistent; only pore size changed. The synthesized silver nanowire, which was crystallized, was dense in the cross sections of the amorphous AAO membrane. The synthesized silver nanowi...

  12. Pulsar Timing Array Based Search for Supermassive Black Hole Binaries in the Square Kilometer Array Era.

    Science.gov (United States)

    Wang, Yan; Mohanty, Soumya D

    2017-04-14

    The advent of next generation radio telescope facilities, such as the Square Kilometer Array (SKA), will usher in an era where a pulsar timing array (PTA) based search for gravitational waves (GWs) will be able to use hundreds of well timed millisecond pulsars rather than the few dozens in existing PTAs. A realistic assessment of the performance of such an extremely large PTA must take into account the data analysis challenge posed by an exponential increase in the parameter space volume due to the large number of so-called pulsar phase parameters. We address this problem and present such an assessment for isolated supermassive black hole binary (SMBHB) searches using a SKA era PTA containing 10^{3} pulsars. We find that an all-sky search will be able to confidently detect nonevolving sources with a redshifted chirp mass of 10^{10}  M_{⊙} out to a redshift of about 28 (corresponding to a rest-frame chirp mass of 3.4×10^{8}  M_{⊙}). We discuss the important implications that the large distance reach of a SKA era PTA has on GW observations from optically identified SMBHB candidates. If no SMBHB detections occur, a highly unlikely scenario in the light of our results, the sky-averaged upper limit on strain amplitude will be improved by about 3 orders of magnitude over existing limits.

  13. Hierarchical ultrathin alumina membrane for the fabrication of unique nanodot arrays

    International Nuclear Information System (INIS)

    Wang, Yuyang; Wang, Yi; Wang, Hailong; Wang, Xinnan; Cong, Ming; Xu, Weiqing; Xu, Shuping

    2016-01-01

    Ultrathin alumina membranes (UTAMs) as evaporation masks have been a powerful tool for the fabrication of high-density nanodot arrays and have received much attention in magnetic memory devices, photovoltaics, and nanoplasmonics. In this paper, we report the fabrication of a hierarchical ultrathin alumina membrane (HUTAM) with highly ordered submicro/nanoscale channels and its application as an evaporation mask for the realization of unique non-hexagonal nanodot arrays dependent on the geometrical features of the HUTAM. This is the first report of a UTAM with a hierarchical geometry, breaking the stereotype that only limited sets of nanopatterns can be realized using the UTAM method (with typical inter-pore distance of 100 nm). The fabrication of a HUTAM is discussed in detail. An improved, longer wet etching time than previously reported is found to effectively remove the barrier layer and widen the pores of a HUTAM. A growth sustainability issue brought about by pre-patterning is discussed. Spectral comparison was made to distinguish the UTAM nanodots and HUTAM nanodots. Our results can be an inspiration for more sophisticated applications of pre-patterned anodized aluminum oxide in photocatalysis, photovoltaics, and nanoplasmonics. (paper)

  14. Resonant Excitation of Terahertz Surface Plasmons in Subwavelength Metal Holes

    Directory of Open Access Journals (Sweden)

    Weili Zhang

    2007-01-01

    Full Text Available We present a review of experimental studies of resonant excitation of terahertz surface plasmons in two-dimensional arrays of subwavelength metal holes. Resonant transmission efficiency higher than unity was recently achieved when normalized to the area occupied by the holes. The effects of hole shape, hole dimensions, dielectric function of metals, polarization dependence, and array film thickness on resonant terahertz transmission in metal arrays were investigated by the state-of-the-art terahertz time-domain spectroscopy. In particular, extraordinary terahertz transmission was demonstrated in arrays of subwavelength holes made even from Pb, a generally poor metal, and having thickness of only one-third of skin depth. Terahertz surface plasmons have potential applications in terahertz imaging, biosensing, interconnects, and development of integrated plasmonic components for terahertz generation and detection.

  15. Two Cases of Severe Degeneration of the Macula Following Vitrectomy with Indocyanine Green-Assisted Internal Limiting Membrane Peeling for Idiopathic Macular Hole

    OpenAIRE

    Inoue, Junji; Sakuma, Toshiro; Kiyokawa, Masatoshi; Kobayashi, Yasuhiko; Takebayashi, Hiroshi; Mizota, Atsushi; Tanaka, Minoru

    2008-01-01

    We describe three eyes of two cases of severe degeneration of the macula following vitrectomy with indocyanine green-assisted internal limiting membrane peeling for idiopathic macular hole. We need to remember the possibility of these complications and have to select the procedures that are safest to use for macular hole surgery.

  16. Co3O4 nanoneedle@electroactive nickel boride membrane core/shell arrays: A novel hybrid for enhanced capacity

    International Nuclear Information System (INIS)

    Li, Tingting; Zhu, Congxu; Yang, Xiaogang; Gao, Yuanhao; He, Weiwei; Yue, Hongwei; Zhao, Hongxiao

    2017-01-01

    Graphical abstract: Active nickel boride membrane anchored Co 3 O 4 nanoneedle arrays hybrid is synthesized via rapid interface reaction. The optimized core/shell nanostructure demonstrates greatly enhanced electrochemical properties. Display Omitted -- Highlights: •Active nickel boride membrane anchored Co 3 O 4 nanoneedle arrays core-shell hybrid architectures was fabricated via rapid interface reaction. •Specific capacity was improved by synergy between highly active components and optimized electron transfer microstructure. •The assembled asymmetric supercapacitor device exhibited excellent electrochemical performance. -- Abstract: Exploring novel hybrid materials with efficient microstructure using facile approaches is highly urgent in designing supercapacitor electrodes. Here, the Ni-B membrane was used for coating the porous Co 3 O 4 nanoneedle arrays which supported on the nickel foam (NF) frameworks through a rapid chemical reduction process (denoted as NF/Co 3 O 4 @NiB). The Ni-B membrane both provided sufficient active sites for redox reactions and inhibited the aggregation of formed hybrid architectures. Benefiting from the unique structural design and strongly coupled effects between porous Co 3 O 4 arrays and Ni-B membrane, the resulted NF/Co 3 O 4 @NiB electrode exhibited high areal capacitance of 3.47 F cm −2 (0.48 mAh cm −2 ) at a current density of 2.5 mA cm −2 , an excellent rate capability while maintaining 95.5% capacity retention after 2000 cycles. The asymmetric supercapacitor constructed with the NF/Co 3 O 4 @NiB as positive electrode and hierarchical porous carbon (HPC) as negative electrode also showed ideal capacitive behavior, and simultaneously delivered high energy and power densities. The easily decoration of Ni-B membrane on various active nanoarrays may arouse more novel design about hybrid architectures for large-scale applications.

  17. Design and Development of an Array of Dielectric Suspended Membranes for Microhotplate Applications

    Directory of Open Access Journals (Sweden)

    Mahanth Prasad

    2014-05-01

    Full Text Available The paper presents the design, fabrication and characterization of an array of suspended dielectric suspended membranes for microhotplate applications. A single cell membrane (100 µm ´ 100 µm made of two different dielectric layers: SiO2 and Si3N4 separately, was designed and simulated using ANSYS 10.0. The simulation of stress generated in different dielectric membranes as a function of temperature is reported. The thickness of both layers was taken as 0.3 µm. The membranes of both SiO2 and Si3N4 dielectrics were fabricated on silicon substrate by bulk micromachining technique using TMAH solution. The buckling of the beam and breakage of membranes made of high-stress Si3N4 film are reported. The simulated results were verified by experiments. The membrane made of SiO2 layer was found to be more suitable in comparison to high-stress Si3N4 layer for microhotplate applications. The present approach provides high yield at low cost for fabrication of microhotplates for gas sensing applications.

  18. Freestanding membrane composed of micro-ring array with ultrahigh sidewall aspect ratio for application in lightweight cathode arrays

    Science.gov (United States)

    Wang, Lanlan; Liu, Hongzhong; Jiang, Weitao; Gao, Wei; Chen, Bangdao; Li, Xin; Ding, Yucheng; An, Ningli

    2014-12-01

    A freestanding multilayer ultrathin nano-membrane (FUN-membrane) with a micro-ring array (MRA) is successfully fabricated through the controllable film deposition. Each micro-ring of FUN-membrane is 3 μm in diameter, 2 μm in height and sub-100 nm in sidewall thickness, demonstrating an ultrahigh sidewall aspect ratio of 20:1. In our strategy, a silica layer (200 nm in thickness), a chromium transition layer (5 nm-thick) and a gold layer (40 nm-thick), were in sequence deposited on patterned photoresist. After removal of the photoresist by lift-off process, a FUN-membrane with MRA was peeled off from the substrate, where the gold layer acted as a protecting layer to prevent the MRA from fracture. The FUN-membrane was then transferred to a flexible polycarbonate (PC) sheet coated with indium tin oxide (ITO) layer, which was then used as a flexible and lightweight cathode. Remarkably, the field emission effect of the fabricated FUN-membrane cathode performs a high field-enhancement factor of 1.2 × 104 and a low turn-on voltage of 2 V/μm, indicating the advantages of the sharp metal edge of MRA. Due to the rational design and material versatility, the FUN-membrane thus could be transferred to either rigid or flexible substrate, even curved surface, such as the skin of bio-robot's arm or leg. Additionally, the FUN-membrane composed of MRA with extremely high aspect ratio of insulator-metal sidewall, also provides potential applications in optical devices, lightweight and flexible display devices, and electronic eye imagers.

  19. Laser-drilled micro-hole arrays on polyurethane synthetic leather for improvement of water vapor permeability

    International Nuclear Information System (INIS)

    Wu, Y.; Wang, A.H.; Zheng, R.R.; Tang, H.Q.; Qi, X.Y.; Ye, B.

    2014-01-01

    Three kinds of lasers at 1064, 532 and 355 nm wavelengths respectively were adopted to construct micro-hole arrays on polyurethane (PU) synthetic leather with an aim to improve water vapor permeability (WVP) of PU synthetic leather. The morphology of the laser-drilled micro-holes was observed to optimize laser parameters. The WVP and slit tear resistance of the laser-drilled leather were measured. Results show that the optimized pulse energy for the 1064, 532 and 355 nm lasers are 0.8, 1.1 and 0.26 mJ, respectively. The diameters of the micro-holes drilled with the optimized laser pulse energy were about 20, 15 and 10 μm, respectively. The depths of the micro-holes drilled with the optimized pulse energy were about 21, 60 and 69 μm, respectively. Compared with the untreated samples, the highest WVP growth ratio was 38.4%, 46.8% and 53.5% achieved by the 1064, 532 and 355 nm lasers, respectively. And the highest decreasing ratio of slit tear resistance was 11.1%, 14.8%, and 22.5% treated by the 1064, 532 and 355 nm lasers, respectively. Analysis of the interaction mechanism between laser beams at three kinds of laser wavelengths and the PU synthetic leather revealed that laser micro-drilling at 355 nm wavelength displayed both photochemical ablation and photothermal ablation, while laser micro-drilling at 1064 and 532 nm wavelengths leaded to photothermal ablation only.

  20. Laser-drilled micro-hole arrays on polyurethane synthetic leather for improvement of water vapor permeability

    Science.gov (United States)

    Wu, Y.; Wang, A. H.; Zheng, R. R.; Tang, H. Q.; Qi, X. Y.; Ye, B.

    2014-06-01

    Three kinds of lasers at 1064, 532 and 355 nm wavelengths respectively were adopted to construct micro-hole arrays on polyurethane (PU) synthetic leather with an aim to improve water vapor permeability (WVP) of PU synthetic leather. The morphology of the laser-drilled micro-holes was observed to optimize laser parameters. The WVP and slit tear resistance of the laser-drilled leather were measured. Results show that the optimized pulse energy for the 1064, 532 and 355 nm lasers are 0.8, 1.1 and 0.26 mJ, respectively. The diameters of the micro-holes drilled with the optimized laser pulse energy were about 20, 15 and 10 μm, respectively. The depths of the micro-holes drilled with the optimized pulse energy were about 21, 60 and 69 μm, respectively. Compared with the untreated samples, the highest WVP growth ratio was 38.4%, 46.8% and 53.5% achieved by the 1064, 532 and 355 nm lasers, respectively. And the highest decreasing ratio of slit tear resistance was 11.1%, 14.8%, and 22.5% treated by the 1064, 532 and 355 nm lasers, respectively. Analysis of the interaction mechanism between laser beams at three kinds of laser wavelengths and the PU synthetic leather revealed that laser micro-drilling at 355 nm wavelength displayed both photochemical ablation and photothermal ablation, while laser micro-drilling at 1064 and 532 nm wavelengths leaded to photothermal ablation only.

  1. Clinical and cost-effectiveness of internal limiting membrane peeling for patients with idiopathic full thickness macular hole. Protocol for a Randomised Controlled Trial: FILMS (Full-thickness macular hole and Internal Limiting Membrane peeling Study

    Directory of Open Access Journals (Sweden)

    Cook Jonathan

    2008-11-01

    Full Text Available Abstract Background A full-thickness macular hole (FTMH is a common retinal condition associated with impaired vision. Randomised controlled trials (RCTs have demonstrated that surgery, by means of pars plana vitrectomy and post-operative intraocular tamponade with gas, is effective for stage 2, 3 and 4 FTMH. Internal limiting membrane (ILM peeling has been introduced as an additional surgical manoeuvre to increase the success of the surgery; i.e. increase rates of hole closure and visual improvement. However, little robust evidence exists supporting the superiority of ILM peeling compared with no-peeling techniques. The purpose of FILMS (Full-thickness macular hole and Internal Limiting Membrane peeling Study is to determine whether ILM peeling improves the visual function, the anatomical closure of FTMH, and the quality of life of patients affected by this disorder, and the cost-effectiveness of the surgery. Methods/Design Patients with stage 2–3 idiopathic FTMH of less or equal than 18 months duration (based on symptoms reported by the participant and with a visual acuity ≤ 20/40 in the study eye will be enrolled in this FILMS from eight sites across the UK and Ireland. Participants will be randomised to receive combined cataract surgery (phacoemulsification and intraocular lens implantation and pars plana vitrectomy with postoperative intraocular tamponade with gas, with or without ILM peeling. The primary outcome is distance visual acuity at 6 months. Secondary outcomes include distance visual acuity at 3 and 24 months, near visual acuity at 3, 6, and 24 months, contrast sensitivity at 6 months, reading speed at 6 months, anatomical closure of the macular hole at each time point (1, 3, 6, and 24 months, health related quality of life (HRQOL at six months, costs to the health service and the participant, incremental costs per quality adjusted life year (QALY and adverse events. Discussion FILMS will provide high quality evidence on the

  2. A novel microneedle array for the treatment of hydrocephalus.

    Science.gov (United States)

    Oh, Jonghyun; Liu, Kewei; Medina, Tim; Kralick, Francis; Noh, Hongseok Moses

    2014-06-01

    We present a microfabricated 10 by 10 array of microneedles for the treatment of a neurological disease called communicating hydrocephalus. Together with the previously reported microvalve array, the current implantable microneedle array completes the microfabricated arachnoid granulations (MAGs) that mimic the function of normal arachnoid granulations (AGs). The microneedle array was designed to enable the fixation of the MAGs through dura mater membrane in the brain and thus provide a conduit for the flow of cerebrospinal fluid (CSF). Cone-shaped microneedles with hollow channels were fabricated using a series of microfabrication techniques: SU-8 photolithography for tapered geometry, reactive ion etching for sharpening the microneedles, 248 nm deep UV excimer laser machining for creating through-hole inside the microneedles, and metal sputtering for improved rigidity. Puncture tests were conducted using porcine dura mater and the results showed that the fabricated microneedle array is strong enough to pierce the dura mater. The in-vitro biocompatibility test result showed that none of the 100 outlets of the microneedles exposed to the bloodstream were clogged significantly by blood cells. We believe that these test results demonstrate the potential use of the microneedle array as a new treatment of hydrocephalus.

  3. Value of internal limiting membrane peeling in surgery for idiopathic macular hole stage 2 and 3: a randomised clinical trial

    DEFF Research Database (Denmark)

    Christensen, U C; Krøyer, K; Sander, B

    2009-01-01

    AIM: To determine the effect of internal limiting membrane (ILM) peeling on anatomical and functional success rates in stage 2 and 3 idiopathic macular hole surgery (MHS). METHODS: Randomised clinical trial of stage 2 and 3 idiopathic macular hole without visible epiretinal fibrosis and with less...... than 1 year's duration of symptoms. Eyes were randomised to (1) vitrectomy alone without retinal surface manipulation, (2) vitrectomy plus 0.05% isotonic Indocyanine Green (ICG)-assisted ILM peeling or (3) vitrectomy plus 0.15% Trypan Blue (TB)-assisted ILM peeling. Main outcomes were hole closure...... after 3 and 12 months and best-corrected visual acuity after 12 months. RESULTS: 78 eyes were enrolled. Primary closure rates were significantly higher with ILM peeling than without peeling for both stage 2 holes (ICG peeling 100%, non-peeling 55%, p = 0.014) and for stage 3 holes (ICG peeling 91%, TB...

  4. Vitrectomy with Internal Limiting Membrane Peeling versus No Peeling for Idiopathic Full-Thickness Macular Hole

    DEFF Research Database (Denmark)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil W

    2014-01-01

    OBJECTIVE: To determine whether internal limiting membrane (ILM) peeling improves anatomic and functional outcomes of full-thickness macular hole (FTMH) surgery when compared with the no-peeling technique. DESIGN: Systematic review and individual participant data (IPD) meta-analysis undertaken...... under the auspices of the Cochrane Eyes and Vision Group. Only randomized controlled trials (RCTs) were included. PARTICIPANTS AND CONTROLS: Patients with idiopathic stage 2, 3, and 4 FTMH undergoing vitrectomy with or without ILM peeling. INTERVENTION: Macular hole surgery, including vitrectomy and gas...... endotamponade with or without ILM peeling. MAIN OUTCOME MEASURES: Primary outcome was best-corrected distance visual acuity (BCdVA) at 6 months postoperatively. Secondary outcomes were BCdVA at 3 and 12 months; best-corrected near visual acuity (BCnVA) at 3, 6, and 12 months; primary (after a single surgery...

  5. Outcomes of 23-gauge pars plana vitrectomy and internal limiting membrane peeling with brilliant blue in macular hole

    Directory of Open Access Journals (Sweden)

    Nohutcu A

    2011-08-01

    Full Text Available Huseyin Sanisoglu1, Mehmet Sahin Sevim1, Betul Aktas1, Semra Sevim2, Ahmet Nohutcu11Haydarpasa Numune Education and Research Hospital, Department of Ophthalmology, 2Uskudar State Hospital, Eye Clinic, Istanbul, TurkeyPurpose: The evaluation of anatomic and visual outcomes in macular hole cases treated with internal limiting membrane (ILM peeling, brilliant blue (BB, and 23-gauge pars plana vitrectomy (PPV.Materials and methods: Fifty eyes of 48 patients who presented between July 2007 and December 2009 with the diagnosis of stage 2, 3, or 4 macular holes according to Gass Classification who had undergone PPV and ILM peeling were included in this study. Pre- and postoperative macular examinations were assessed with spectral-domain optical coherence tomography. 23 G sutureless PPV and ILM peeling with BB was performed on all patients.Results: The mean age of patients was 63.34 ± 9.6 years. Stage 2 macular hole was determined in 17 eyes (34%, stage 3 in 24 eyes (48%, and stage 4 in 9 eyes (18%. The mean follow-up time was 13.6 ± 1.09 months. Anatomic closure was detected in 46/50 eyes (92%, whereas, in four cases, macular hole persisted and a second operation was not required due to subretinal fluid drainage. At follow-up after 2 months, persistant macular hole was detected in one case and it was closed with reoperation. At 12 months, an increase in visual acuity in 41 eyes was observed, while it remained at the same level in six eyes. In three eyes visual acuity decreased. There was a postoperative statistically significant increase in visual acuity in stage 2 and 3 cases (P < 0.05, however, no increase in visual acuity in stage 4 cases was observed.Conclusion: PPV and ILM peeling in stage 2, 3, and 4 macular hole cases provide successful anatomic outcomes, however, in delayed cases, due to photoreceptor loss, it has no effect on functional recovery. BB, used for clarity of ILM, may be beneficial due to its low retinal toxicity.Keywords: macular

  6. Retinal thinning after internal limiting membrane peeling for idiopathic macular hole.

    Science.gov (United States)

    Imamura, Yutaka; Ishida, Masahiro

    2018-03-01

    To determine the changes in retinal thickness and whether they correlate with the size of the macular hole (MH) after vitrectomy with internal limiting membrane peeling. Retrospective, interventional case series METHODS: Consecutive patients with an MH and undergoing pars plana vitrectomy with internal limiting membrane peeling were studied. The retinal thicknesses in the inner 4 sectors as defined by the Early Treatment of Diabetic Retinopathy Study were measured using spectral-domain optical coherence tomography (SD-OCT) before and at 2 weeks and 1, 3, 6, and 12 months after the surgery. The basal and minimum diameters of the MHs were measured. The correlations between the retinal thicknesses and the size of the MH were determined. Thirty-three eyes of 32 consecutive patients (18 women; mean age, 64.2 ± 8.8 years) with an MH were studied. Thirteen eyes had a stage-2 MH; 12 eyes, a stage-3 MH; and 8 eyes, a stage-4 MH. The mean retinal thickness in the temporal sector was 362.8 ± 29.9 µm preoperatively, 337.9 ± 20.6 µm at 2 weeks postoperatively, and 307.6 ± 20.2 µm at 12 months postoperatively (P peeling.

  7. Digital electrostatic acoustic transducer array

    KAUST Repository

    Carreno, Armando Arpys Arevalo

    2016-12-19

    In this paper we present the fabrication and characterization of an array of electrostatic acoustic transducers. The array is micromachined on a silicon wafer using standard micro-machining techniques. Each array contains 2n electrostatic transducer membranes, where “n” is the bit number. Every element of the array has a hexagonal membrane shape structure, which is separated from the substrate by 3µm air gap. The membrane is made out 5µm thick polyimide layer that has a bottom gold electrode on the substrate and a gold top electrode on top of the membrane (250nm). The wafer layout design was diced in nine chips with different array configurations, with variation of the membrane dimensions. The device was tested with 90 V giving and sound output level as high as 35dB, while actuating all the elements at the same time.

  8. Digital electrostatic acoustic transducer array

    KAUST Repository

    Carreno, Armando Arpys Arevalo; Castro, David; Conchouso Gonzalez, David; Kosel, Jü rgen; Foulds, Ian G.

    2016-01-01

    In this paper we present the fabrication and characterization of an array of electrostatic acoustic transducers. The array is micromachined on a silicon wafer using standard micro-machining techniques. Each array contains 2n electrostatic transducer membranes, where “n” is the bit number. Every element of the array has a hexagonal membrane shape structure, which is separated from the substrate by 3µm air gap. The membrane is made out 5µm thick polyimide layer that has a bottom gold electrode on the substrate and a gold top electrode on top of the membrane (250nm). The wafer layout design was diced in nine chips with different array configurations, with variation of the membrane dimensions. The device was tested with 90 V giving and sound output level as high as 35dB, while actuating all the elements at the same time.

  9. Refractive changes after lens-sparing vitrectomy for macular hole and epiretinal membrane

    Directory of Open Access Journals (Sweden)

    Muto T

    2017-08-01

    Full Text Available Tetsuya Muto,1 Tomoharu Nishimura,1 Takefumi Yamaguchi,2 Makoto Chikuda,1 Shigeki Machida1 1Department of Ophthalmology, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Japan; 2Department of Ophthalmology, Tokyo Dental College Ichikawa General Hospital, Ichikawa, Japan Purpose: Cataract progression after lens-sparing vitrectomy might differ according to original posterior segment diseases. Our objective was to analyze the refractive values after lens-sparing vitrectomy for macular hole (MH and epiretinal membrane (ERM. Materials and methods: We reviewed the medical records of 25 MH patients (25 eyes and 23 ERM patients (23 eyes who underwent lens-sparing vitrectomy. Refractive changes in both groups were compared. All patients underwent 20-gauge three-port pars plana vitrectomy. Fluid–air exchange was performed during vitrectomy only in the MH group. The results were analyzed using the unpaired t-test, chi-square test, or Fisher exact probability test, and multivariate analysis. Results: There were no significant differences in the patient’s age (P=0.45. The myopia progression rate (D/month was higher in the MH group after surgery than that in the ERM group (P=0.035. MH group had more females (P=0.043, longer surgical time (P<0.001, and higher frequencies of surgical adjuvants use (triamcinolone acetonide, P=0.019; brilliant blue G, P<0.001. The myopia progression rate in the MH group (R=0.568, P<0.001 correlated with female gender. However, no correlation was observed between longer surgical time and the use of surgical adjuvants. Conclusion: The rate of myopia progression was higher in the MH group. Fluid–air exchange and gender may affect the rate of myopia progression. Keywords: cataract, vitrectomy, macular hole, epiretinal membrane

  10. Tomographic Structural Changes of Retinal Layers after Internal Limiting Membrane Peeling for Macular Hole Surgery.

    Science.gov (United States)

    Faria, Mun Yueh; Ferreira, Nuno P; Cristóvao, Diana M; Mano, Sofia; Sousa, David Cordeiro; Monteiro-Grillo, Manuel

    2018-01-01

    To highlight tomographic structural changes of retinal layers after internal limiting membrane (ILM) peeling in macular hole surgery. Nonrandomized prospective, interventional study in 38 eyes (34 patients) subjected to pars plana vitrectomy and ILM peeling for idiopathic macular hole. Retinal layers were assessed in nasal and temporal regions before and 6 months after surgery using spectral domain optical coherence tomography. Total retinal thickness increased in the nasal region and decreased in the temporal region. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) showed thinning on both nasal and temporal sides of the fovea. The thickness of the outer plexiform layer (OPL) increased. The outer nuclear layer (ONL) and outer retinal layers (ORL) increased in thickness after surgery in both nasal and temporal regions. ILM peeling is associated with important alterations in the inner retinal layer architecture, with thinning of the RNFL-GCL-IPL complex and thickening of OPL, ONL, and ORL. These structural alterations can help explain functional outcome and could give indications regarding the extent of ILM peeling, even though peeling seems important for higher rate of hole closure. © 2017 S. Karger AG, Basel.

  11. Magnetic properties of Fe20 Ni80 antidots: Pore size and array disorder

    International Nuclear Information System (INIS)

    Palma, J.L.; Gallardo, C.; Spinu, L.; Vargas, J.M.; Dorneles, L.S.; Denardin, J.C.; Escrig, J.

    2013-01-01

    Magnetic properties of nanoscale Fe 20 Ni 80 antidot arrays with different hole sizes prepared on top of nanoporous alumina membranes have been studied by means of magnetometry and micromagnetic simulations. The results show a significant increase of the coercivity as well as a reduction of the remanence of the antidot arrays, as compared with their parent continuous film, which depends on the hole size introduced in the Fe 20 Ni 80 thin film. When the external field is applied parallel to the antidots, the reversal of magnetization is achieved by free-core vortex propagation, whereas when the external field is applied perpendicular to the antidots, the reversal occurs through a process other than the coherent rotation (a maze-like pattern). Besides, in-plane hysteresis loops varying the angle show that the degree of disorder in the sample breaks the expected hexagonal symmetry. - Highlights: • Magnetic properties are strongly influenced by the pore diameter of the samples. • Coercive fields for antidots are higher than the values for the continuous film. • Disorder breaks the hexagonal symmetry of the sample. • Each hole acts as a vortex nucleation point. • Antidots have unique properties that allow them to be used in applications

  12. Magnetoelectrolysis of Co nanowire arrays grown in a tracketched polycarbonate membrane

    Energy Technology Data Exchange (ETDEWEB)

    Radu, Florin [BESSY GmbH, Berlin (Germany); Rivero, Guillermo; Marin, Pilar; Hernando, Antonio [Instituto de Magnetismo Aplicado, Madrid (Spain); Sanchez-Barriga, J. [Instituto de Magnetismo Aplicado, Madrid (Spain); BESSY GmbH, Berlin (Germany); Lucas, M. [Inst. fuer Theoretische Physik, Technische Univ. Berlin (Germany)

    2007-07-01

    Arrays of Cobalt nanowires with a controlled length of 6{mu}m have been fabricated by electrochemical deposition into the pores of track-etched polycarbonate membranes with a nominal pore diameter of 30 nm. The magnetic properties of Co-deposited nanowires and the effects of a magnetic field applied during electrodeposition of the arrays have been studied. An enhancement of the mass deposition rate due to the presence of a 50 Oe magnetic field along the nanowire axis has been observed by measuring the experimental development of the current in the electrochemical cell during the fabrication process. X-Ray diffraction measurements reveal a different polycrystalline degree for each deposition configuration, indicating that the crystalline structure of the deposited material has been substantially modified. Magnetic measurements show a clear dependence of the anisotropy directions on the orientation of the magnetic field applied during the electrodeposition.

  13. Piezoelectric transducer array microspeaker

    KAUST Repository

    Carreno, Armando Arpys Arevalo

    2016-12-19

    In this paper we present the fabrication and characterization of a piezoelectric micro-speaker. The speaker is an array of micro-machined piezoelectric membranes, fabricated on silicon wafer using advanced micro-machining techniques. Each array contains 2n piezoelectric transducer membranes, where “n” is the bit number. Every element of the array has a circular shape structure. The membrane is made out four layers: 300nm of platinum for the bottom electrode, 250nm or lead zirconate titanate (PZT), a top electrode of 300nm and a structural layer of 50

  14. SURGICAL OUTCOMES AFTER INVERTED INTERNAL LIMITING MEMBRANE FLAP VERSUS CONVENTIONAL PEELING FOR VERY LARGE MACULAR HOLES.

    Science.gov (United States)

    Narayanan, Raja; Singh, Sumit R; Taylor, Stanford; Berrocal, Maria H; Chhablani, Jay; Tyagi, Mudit; Ohno-Matsui, Kyoko; Pappuru, Rajeev R; Apte, Rajendra S

    2018-04-23

    To evaluate the anatomical and visual outcomes of inverted flap technique of peeling of internal limiting membrane (ILM) versus standard peeling of ILM for macular holes of basal diameter more than 800 μm. Patients with very large idiopathic macular holes more than 800 μm in basal diameter (ranging from 243 μm to 840 μm in minimum diameter) were retrospectively included in the study. In Group A, 18 eyes of 18 patients underwent ILM peeling using the inverted flap technique. In Group B, 18 eyes of 18 patients underwent conventional ILM peeling. The primary endpoint was the rate of hole closure at 6 months after surgery. The secondary outcome measure was the change in best-corrected visual acuity at 6 months after surgery. There were no significant differences in ocular characteristics of the study groups at baseline except for the age distribution. Mean macular hole diameter was 1,162.8 ± 206.0 μm and 1,229.6 ± 228.1 μm in Group A and Group B, respectively. The hole closure rate was 88.9% (16/18) in Group A and 77.8% (14/18) in Group B (P = 0.66). The mean gain in best-corrected visual acuity was higher in Group A than in Group B (P = 0.12) at 6 months, but this was not statistically significant. There were no severe ocular adverse events in either group. In this multicenter series, inverted ILM flap technique did not lead to significantly higher anatomical closure rates than conventional ILM peeling in large macular holes more than 800 μm in diameter.

  15. Fabrication of a micro-hole array on metal foil by nanosecond pulsed laser beam machining using a cover plate

    International Nuclear Information System (INIS)

    Ha, Kyoung Ho; Lee, Se Won; Jee, Won Young; Chu, Chong Nam; Kim, Janggil

    2015-01-01

    A novel laser beam machining (LBM) method is proposed to achieve higher precision and better quality beyond the limits of a commercialized nanosecond pulsed laser system. The use of a cover plate is found to be effective for the precision machining of a thin metal foil at micro scale. For verifying the capability of cover plate laser beam machining (c-LBM) technology, a 30 by 30 array of micro-holes was fabricated on 8 µm-thick stainless steel 304 (STS) foil. As a result, thermal deformation and cracks were significantly reduced in comparison with the results using LBM without a cover plate. The standard deviation of the inscribed and circumscribed circle of the holes with a diameter of 12 µm was reduced to 33% and 81%, respectively and the average roundness improved by 77%. Moreover, the smallest diameter obtainable by c-LBM in the given equipment was found to be 6.9 µm, which was 60% less than the minimum size hole by LBM without a cover plate. (technical note)

  16. Lithography-based fabrication of nanopore arrays in freestanding SiN and graphene membranes

    Science.gov (United States)

    Verschueren, Daniel V.; Yang, Wayne; Dekker, Cees

    2018-04-01

    We report a simple and scalable technique for the fabrication of nanopore arrays on freestanding SiN and graphene membranes based on electron-beam lithography and reactive ion etching. By controlling the dose of the single-shot electron-beam exposure, circular nanopores of any size down to 16 nm in diameter can be fabricated in both materials at high accuracy and precision. We demonstrate the sensing capabilities of these nanopores by translocating dsDNA through pores fabricated using this method, and find signal-to-noise characteristics on par with transmission-electron-microscope-drilled nanopores. This versatile lithography-based approach allows for the high-throughput manufacturing of nanopores and can in principle be used on any substrate, in particular membranes made out of transferable two-dimensional materials.

  17. Magnetic properties of Fe{sub 20} Ni{sub 80} antidots: Pore size and array disorder

    Energy Technology Data Exchange (ETDEWEB)

    Palma, J.L., E-mail: juan.palma.s@usach.cl [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Gallardo, C. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Spinu, L.; Vargas, J.M. [Advanced Material Research Institute (AMRI) and Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States); Dorneles, L.S. [Departamento de Fisica, Universidade Federal de Santa Maria UFSM, Av. Roraima 1000, Camobi, Santa Maria, RS 97105-900 (Brazil); Denardin, J.C.; Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

    2013-10-15

    Magnetic properties of nanoscale Fe{sub 20}Ni{sub 80} antidot arrays with different hole sizes prepared on top of nanoporous alumina membranes have been studied by means of magnetometry and micromagnetic simulations. The results show a significant increase of the coercivity as well as a reduction of the remanence of the antidot arrays, as compared with their parent continuous film, which depends on the hole size introduced in the Fe{sub 20}Ni{sub 80} thin film. When the external field is applied parallel to the antidots, the reversal of magnetization is achieved by free-core vortex propagation, whereas when the external field is applied perpendicular to the antidots, the reversal occurs through a process other than the coherent rotation (a maze-like pattern). Besides, in-plane hysteresis loops varying the angle show that the degree of disorder in the sample breaks the expected hexagonal symmetry. - Highlights: • Magnetic properties are strongly influenced by the pore diameter of the samples. • Coercive fields for antidots are higher than the values for the continuous film. • Disorder breaks the hexagonal symmetry of the sample. • Each hole acts as a vortex nucleation point. • Antidots have unique properties that allow them to be used in applications.

  18. Electrochemical detection of dopamine using arrays of liquid-liquid micro-interfaces created within micromachined silicon membranes

    International Nuclear Information System (INIS)

    Berduque, Alfonso; Zazpe, Raul; Arrigan, Damien W.M.

    2008-01-01

    The detection of protonated dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at arrays of micro-interfaces between two immiscible electrolyte solutions (μITIES) is presented. Microfabricated porous silicon membranes (consisting of eight pores, 26.6 μm in radius and 500 μm pore-pore separation, in a hexagonal layout) were prepared by photolithographic and etching procedures. The membrane pores were fabricated with hydrophobic internal walls so that the organic phase filled the pores and created the liquid interface at the aqueous side of the membrane. These were used for harnessing the benefits of three-dimensional diffusion to the interface and for interface stabilisation. The liquid-liquid interface provides a simple method to overcome the major problem in the voltammetric detection of dopamine at solid electrodes due to the co-existence of ascorbate at higher concentrations. Selectivity for dopamine over ascorbate was achieved by the use of dibenzo-18-crown-6 (DB18C6) for the facilitated ion transfer of dopamine across the μITIES array. Under these conditions, the presence of ascorbate in excess did not interfere in the detection of dopamine and the lowest concentration detectable was ca. 0.5 μM. In addition, the drawback of current signal saturation (non-linear increase of the peak current with the concentration of dopamine) observed at conventional (millimetre-sized) liquid-liquid interfaces was overcome using the microfabricated porous membranes

  19. Magnetoelectrolysis of Co nanowire arrays grown in a track-etched polycarbonate membrane

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Barriga, J. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain)]. E-mail: sbarriga@bessy.de; Lucas, M. [Technische Universitaet Berlin, Institut fuer Theoretische Physik, Hardenbergstr. 36, D-10623 Berlin (Germany); Rivero, G. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain); Marin, P. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain); Hernando, A. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain)

    2007-05-15

    Arrays of Cobalt nanowires with a controlled length of 6{mu}m have been fabricated by electrochemical deposition into the pores of track-etched polycarbonate membranes with a nominal pore diameter of 30nm. The magnetic properties of Co-deposited nanowires and the effects of a magnetic field applied during electrodeposition of the arrays have been studied. An enhancement of the mass deposition rate due to the presence of a 50Oe magnetic field along the nanowire axis has been observed by measuring the experimental development of the current in the electrochemical cell during the fabrication process. X-ray diffraction measurements reveal a different polycrystalline degree for each deposition configuration, indicating that the crystalline structure of the deposited material has been substantially modified. Magnetic measurements show a clear dependence of the anisotropy directions on the orientation of the magnetic field applied during the electrodeposition.

  20. Magnetoelectrolysis of Co nanowire arrays grown in a track-etched polycarbonate membrane

    International Nuclear Information System (INIS)

    Sanchez-Barriga, J.; Lucas, M.; Rivero, G.; Marin, P.; Hernando, A.

    2007-01-01

    Arrays of Cobalt nanowires with a controlled length of 6μm have been fabricated by electrochemical deposition into the pores of track-etched polycarbonate membranes with a nominal pore diameter of 30nm. The magnetic properties of Co-deposited nanowires and the effects of a magnetic field applied during electrodeposition of the arrays have been studied. An enhancement of the mass deposition rate due to the presence of a 50Oe magnetic field along the nanowire axis has been observed by measuring the experimental development of the current in the electrochemical cell during the fabrication process. X-ray diffraction measurements reveal a different polycrystalline degree for each deposition configuration, indicating that the crystalline structure of the deposited material has been substantially modified. Magnetic measurements show a clear dependence of the anisotropy directions on the orientation of the magnetic field applied during the electrodeposition

  1. Microneedle arrays allow lower microbial penetration than hypodermic needles in vitro.

    Science.gov (United States)

    Donnelly, Ryan F; Singh, Thakur Raghu Raj; Tunney, Michael M; Morrow, Desmond I J; McCarron, Paul A; O'Mahony, Conor; Woolfson, A David

    2009-11-01

    In this study we determined, for the first time, the ability of microorganisms to traverse microneedle-induced holes using two different in vitro models. When employing Silescol membranes, the numbers of Candida albicans, Pseudomonas aeruginosa and Staphylococcus epidermidis crossing the membranes were an order of magnitude lower when the membranes were punctured by microneedles rather than a 21G hypodermic needle. Apart from the movement of C. albicans across hypodermic needle-punctured membranes, where 40.2% of the microbial load on control membranes permeated the barrier over 24 h, the numbers of permeating microorganisms was less than 5% of the original microbial load on control membranes. Experiments employing excised porcine skin and radiolabelled microorganisms showed that the numbers of microorganisms penetrating skin beyond the stratum corneum were approximately an order of magnitude greater than the numbers crossing Silescol membranes in the corresponding experiments. Approximately 10(3) cfu of each microorganism adhered to hypodermic needles during insertion. The numbers of microorganisms adhering to MN arrays were an order of magnitude higher in each case. We have shown here that microneedle puncture resulted in significantly less microbial penetration than did hypodermic needle puncture and that no microorganisms crossed the viable epidermis in microneedle-punctured skin, in contrast to needle-punctured skin. Given the antimicrobial properties of skin, it is, therefore, likely that application of microneedle arrays to skin in an appropriate manner would not cause either local or systemic infection in normal circumstances in immune-competent patients. In supporting widespread clinical use of microneedle-based delivery systems, appropriate animal studies are now needed to conclusively demonstrate this in vivo. Safety in patients will be enhanced by aseptic or sterile manufacture and by fabricating microneedles from self-disabling materials (e

  2. Decreased retinal sensitivity after internal limiting membrane peeling for macular hole surgery.

    Science.gov (United States)

    Tadayoni, Ramin; Svorenova, Ivana; Erginay, Ali; Gaudric, Alain; Massin, Pascale

    2012-12-01

    To compare the retinal sensitivity and frequency of microscotomas found by spectral domain optical coherence tomography (SD-OCT) combined with scanning laser ophthalmoscopy (SLO) microperimetry after idiopathic macular hole closure, in eyes that underwent internal limiting membrane (ILM) peeling and eyes that did not. This was a retrospective, non-randomised, comparative study. Combined SD-OCT and SLO microperimetry was performed in 16 consecutive eyes after closure of an idiopathic macular hole. A customised microperimetry pattern with 29 measurement points was used. The ILM was peeled in 8/16 eyes. The main outcome measure was mean retinal sensitivity. Mean retinal sensitivity (in dB) was lower after peeling: 9.80 ± 2.35 dB with peeling versus 13.19 ± 2.92 without (p=0.0209). Postoperative microscotomas were significantly more frequent after ILM peeling: 11.3 ± 6.6 points with retinal sensitivity below 10 dB in eyes that underwent peeling versus 2.9 ± 4.6 in those that did not (p=0.0093). These results suggest that ILM peeling may reduce retinal sensitivity, and significantly increase the incidence of microscotomas. Until a prospective trial confirming or not these results, it seems justified to avoid peeling the ILM when its potential benefit seems minor or unproved, and when peeling is carried out, to limit the surface peeled to the bare minimum.

  3. Multilayered membranes with tuned well arrays to be used as regenerative patches.

    Science.gov (United States)

    Martins, Nádia I; Sousa, Maria P; Custódio, Catarina A; Pinto, Vânia C; Sousa, Paulo J; Minas, Graça; Cleymand, Franck; Mano, João F

    2017-07-15

    Membranes have been explored as patches in tissue repair and regeneration, most of them presenting a flat geometry or a patterned texture at the nano/micrometer scale. Herein, a new concept of a flexible membrane featuring well arrays forming pore-like environments to accommodate cell culture is proposed. The processing of such membranes using polysaccharides is based on the production of multilayers using the layer-by-layer methodology over a patterned PDMS substrate. The detached multilayered membrane exhibits a layer of open pores at one side and a total thickness of 38±2.2µm. The photolithography technology used to produce the molds allows obtaining wells on the final membranes with a tuned shape and micro-scale precision. The influence of post-processing procedures over chitosan/alginate films with 100 double layers, including crosslinking with genipin or fibronectin immobilization, on the adhesion and proliferation of human osteoblast-like cells is also investigated. The results suggest that the presence of patterned wells affects positively cell adhesion, morphology and proliferation. In particular, it is seen that cells colonized preferentially the well regions. The geometrical features with micro to sub-millimeter patterned wells, together with the nano-scale organization of the polymeric components along the thickness of the film will allow to engineer highly versatile multilayered membranes exhibiting a pore-like microstructure in just one of the sides, that could be adaptable in the regeneration of multiple tissues. Flexible multilayered membranes containing multiple micro-reservoirs are found as potential regenerative patches. Layer-by-layer (LbL) methodology over a featured PDMS substrate is used to produce patterned membranes, composed only by natural-based polymers, that can be easily detached from the PDMS substrate. The combination of nano-scale control of the polymeric organization along the thickness of the chitosan/alginate (CHT

  4. Vitrectomy with internal limiting membrane peeling vs no peeling for Macular Hole-induced Retinal Detachment (MHRD): a meta-analysis.

    Science.gov (United States)

    Su, Jing; Liu, Xinquan; Zheng, Lijun; Cui, Hongping

    2015-06-20

    we conducted our meta-analysis of published studies to assess existing evidence about the efficacy and safety of vitrectomy with ILM peeling vs. that of vitrectomy with no ILM peeling for Macular hole-induced retinal detachment. Databases, including Pubmed, Cochrane Library, Ovid, Web of Science, Wanfang and CNKI, were searched to identify studies comparing outcomes following vitrectomy with ILM peeling and that with no ILM peeling for macular hole-induced retinal detachment. The meta-analysis was performed by RevMan 5.1. Six comparative studies comprising 180 eyes were identified. It was indicated that the rate of retinal reattachment (Odds ratio (OR) = 3.03, 95 % Confidence interval (CI):1.35 to 6.78; P = 0.007) and macular hole closure (OR = 6.74, 95 % CI:3.26 to 13.93; P peeling than that in the group of vitrectomy with no ILM peeling. However, the improved BCVA (Weighted mean difference (WMD) = 0.14, 95 % CI: -0.20 to 0.47; P = 0.42) and the rate of postoperative complications were similar between the two groups. Vitrectomy with internal limiting membrane peeling is an efficient and safe procedure for macular hole-induced retinal detachment.

  5. Analysis of the current density characteristics in through-mask electrochemical micromachining (TMEMM for fabrication of micro-hole arrays on invar alloy film

    Directory of Open Access Journals (Sweden)

    Da-som JIN

    2017-06-01

    Full Text Available Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes (OLEDs because of its low thermal expansion coefficient (1.86 × 10−6 cm/°C. To fabricate micro-hole arrays on 30 μm invar alloy film, through-mask electrochemical micromachining (TMEMM was developed and combined with a portion of the photolithography etching process. For precise hole shapes, patterned photoresist (PR film was applied as an insulating mask. To investigate the relationship between the current density and the material removal rate, the principle of the electrochemical machining was studied with a focus on the equation. The finite element method (FEM was used to verify the influence of each parameter on the current density on the invar alloy film surface. The parameters considered were the thickness of the PR mask, inter-electrode gap (IEG, and electrolyte concentration. Design of experiments (DOE was used to figure out the contribution of each parameter. A simulation was conducted with varying parameters to figure out their relationships with the current density. Optimization was conducted to select the suitable conditions. An experiment was carried out to verify the simulation results. It was possible to fabricate micro-hole arrays on invar alloy film using TMEMM, which is a promising method that can be applied to fabrications of OLEDs shadow masks.

  6. Gravitational interaction of a black hole with nearby matter

    International Nuclear Information System (INIS)

    Price, R.H.; Thorne, K.S.; Redmount, I.H.

    1986-01-01

    The interaction of a black hole with nearby matter is examined with a membrane paradigm which includes a 3+1 formalism that splits spacetime coordinates into a family of three-dimensional spacelike hypersurfaces and one-dimensional time. Emphasis is placed on the influence of matter and its gravity on the shape and evolution of the hole horizon and the effects of the hole on the matter. Universal time coordinates and fiduciary observers are defined outside a dynamically perturbed black hole and tidal gravitational fields are assumed to carry information on the disturbances. The exterior of the hole is examined in terms of the perturbed tidal fields and the material energy, momentum and stress which produce the perturbations. Finally, a membrane model is derived for the interaction of matter and its tidal fields with the stretched null horizon

  7. Two-dimensional photonic crystal arrays for polymer:fullerene solar cells.

    Science.gov (United States)

    Nam, Sungho; Han, Jiyoung; Do, Young Rag; Kim, Hwajeong; Yim, Sanggyu; Kim, Youngkyoo

    2011-11-18

    We report the application of two-dimensional (2D) photonic crystal (PC) array substrates for polymer:fullerene solar cells of which the active layer is made with blended films of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The 2D PC array substrates were fabricated by employing a nanosphere lithography technique. Two different hole depths (200 and 300 nm) were introduced for the 2D PC arrays to examine the hole depth effect on the light harvesting (trapping). The optical effect by the 2D PC arrays was investigated by the measurement of optical transmittance either in the direction normal to the substrate (direct transmittance) or in all directions (integrated transmittance). The results showed that the integrated transmittance was higher for the 2D PC array substrates than the conventional planar substrate at the wavelengths of ca. 400 nm, even though the direct transmittance of 2D PC array substrates was much lower over the entire visible light range. The short circuit current density (J(SC)) was higher for the device with the 2D PC array (200 nm hole depth) than the reference device. However, the device with the 2D PC array (300 nm hole depth) showed a slightly lower J(SC) value at a high light intensity in spite of its light harvesting effect proven at a lower light intensity.

  8. Nonrotating and slowly rotating holes

    International Nuclear Information System (INIS)

    Macdonald, D.A.; Price, R.H.; Thorne, K.S.; Suen, W.M.

    1986-01-01

    The 3+1 formalism is applied to model Schwarzschild spacetime around a black hole. Particular note is taken of the 3+1 split of the laws of electrodynamics, and of the tendency of the approach to freeze motion at the event horizon. The null horizon is replaced with a timelike physical membrane which exhibits mechanical, thermodynamic and electrical properties, and which stretches the horizon. The usefulness of the stretching approach is illustrated by considering a black hole penetrated by vibrating magnetic field lines anchored in a perfectly conducting surrounding sphere. The necessity of modeling the field structure near the actual horizon is avoided by having the field end at the membrane. The surface charge, current, resistivity and ohmic heating of the stretched horizon are also considered, and the Lorentz force imparted to the stretched horizon surface by the field lines is investigated by examining a nearly Schwarzschild hole behaving as the rotor of an electric motor

  9. Quantum Black Holes as Holograms in AdS Braneworlds

    CERN Document Server

    Emparan, R; Kaloper, Nemanja; Emparan, Roberto; Fabbri, Alessandro; Kaloper, Nemanja

    2002-01-01

    We propose a new approach for using the AdS/CFT correspondence to study quantum black hole physics. The black holes on a brane in an AdS$_{D+1}$ braneworld that solve the classical bulk equations are interpreted as duals of {\\it quantum-corrected} $D$-dimensional black holes, rather than classical ones, of a conformal field theory coupled to gravity. We check this explicitly in D=3 and D=4. In D=3 we reinterpret the existing exact solutions on a flat membrane as states of the dual 2+1 CFT. We show that states with a sufficiently large mass really are 2+1 black holes where the quantum corrections dress the classical conical singularity with a horizon and censor it from the outside. On a negatively curved membrane, we reinterpret the classical bulk solutions as quantum-corrected BTZ black holes. In D=4 we argue that the bulk solution for the brane black hole should include a radiation component in order to describe a quantum-corrected black hole in the 3+1 dual. Hawking radiation of the conformal field is then ...

  10. Distinguishing between deep trapping transients of electrons and holes in TiO2 nanotube arrays using planar microwave resonator sensor.

    Science.gov (United States)

    Zarifi, Mohammad H; Wiltshire, Benjamin Daniel; Mahdi, Najia; Shankar, Karthik; Daneshmand, Mojgan

    2018-05-16

    A large signal DC bias and a small signal microwave bias were simultaneously applied to TiO2 nanotube membranes mounted on a planar microwave resonator. The DC bias modulated the electron concentration in the TiO2 nanotubes, and was varied between 0 and 120 V in this study. Transients immediately following the application and removal of DC bias were measured by monitoring the S-parameters of the resonator as a function of time. The DC bias stimulated Poole-Frenkel type trap-mediated electrical injection of excess carriers into TiO2 nanotubes which resulted in a near constant resonant frequency but a pronounced decrease in the microwave amplitude due to free electron absorption. When ultraviolet illumination and DC bias were both present and then step-wise removed, the resonant frequency shifted due to trapping -mediated change in the dielectric constant of the nanotube membranes. Characteristic lifetimes of 60-80 s, 300-800 s and ~3000 s were present regardless of whether light or bias was applied and are also observed in the presence of a hole scavenger, which we attribute to oxygen adsorption and deep electron traps while another characteristic lifetime > 9000 s was only present when illumination was applied, and is attributed to the presence of hole traps.

  11. Introduction to General Relativity and Black Holes (5/5)

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

  12. Introduction to General Relativity and Black Holes (3/5)

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

  13. Introduction to General Relativity and Black Holes (1/5)

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

  14. Introduction to General Relativity and Black Holes (2/5)

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

  15. Introduction to General Relativity and Black Holes (4/5)

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

  16. Thermal decay of the cosmological constant into black holes

    International Nuclear Information System (INIS)

    Gomberoff, Andres; Henneaux, Marc; Teitelboim, Claudio; Wilczek, Frank

    2004-01-01

    We show that the cosmological constant may be reduced by thermal production of membranes by the cosmological horizon, analogous to a particle 'going over the top of the potential barrier', rather than tunneling through it. The membranes are endowed with charge associated with the gauge invariance of an antisymmetric gauge potential. In this new process, the membrane collapses into a black hole; thus, the net effect is to produce black holes out of the vacuum energy associated with the cosmological constant. We study here the corresponding Euclidean configurations ('thermalons') and calculate the probability for the process in the leading semiclassical approximation

  17. Membrane-based oligonucleotide array developed from multiple markers for the detection of many Phytophthora species.

    Science.gov (United States)

    Chen, Wen; Djama, Zeinab Robleh; Coffey, Michael D; Martin, Frank N; Bilodeau, Guillaume J; Radmer, Lorien; Denton, Geoff; Lévesque, C André

    2013-01-01

    Most Phytophthora spp. are destructive plant pathogens; therefore, effective monitoring and accurate early detection are important means of preventing potential epidemics and outbreaks of diseases. In the current study, a membrane-based oligonucleotide array was developed that can detect Phytophthora spp. reliably using three DNA regions; namely, the internal transcribed spacer (ITS), the 5' end of cytochrome c oxidase 1 gene (cox1), and the intergenic region between cytochrome c oxidase 2 gene (cox2) and cox1 (cox2-1 spacer). Each sequence data set contained ≈250 sequences representing 98 described and 15 undescribed species of Phytophthora. The array was validated with 143 pure cultures and 35 field samples. Together, nonrejected oligonucleotides from all three markers have the ability to reliably detect 82 described and 8 undescribed Phytophthora spp., including several quarantine or regulated pathogens such as Phytophthora ramorum. Our results showed that a DNA array containing signature oligonucleotides designed from multiple genomic regions provided robustness and redundancy for the detection and differentiation of closely related taxon groups. This array has the potential to be used as a routine diagnostic tool for Phytophthora spp. from complex environmental samples without the need for extensive growth of cultures.

  18. BMS invariance and the membrane paradigm

    International Nuclear Information System (INIS)

    Penna, Robert F.

    2016-01-01

    The Bondi-van der Burg-Metzner-Sachs (BMS) group is the asymptotic symmetry group of asymptotically flat spacetime. It is infinite dimensional and entails an infinite number of conservation laws. According to the black hole membrane paradigm, null infinity (in asymptotically flat spacetime) and black hole event horizons behave like fluid membranes. The fluid dynamics of the membrane is governed by an infinite set of symmetries and conservation laws. Our main result is to point out that the infinite set of symmetries and conserved charges of the BMS group and the membrane paradigm are the same. This relationship has several consequences. First, it sheds light on the physical interpretation of BMS conservation laws. Second, it generalizes the BMS conservation laws to arbitrary subregions of arbitrary null surfaces. Third, it clarifies the identification of the superrotation subgroup of the BMS group. We briefly comment on the black hole information problem.

  19. Plasmonic nanoparticle lithography: Fast resist-free laser technique for large-scale sub-50 nm hole array fabrication

    Science.gov (United States)

    Pan, Zhenying; Yu, Ye Feng; Valuckas, Vytautas; Yap, Sherry L. K.; Vienne, Guillaume G.; Kuznetsov, Arseniy I.

    2018-05-01

    Cheap large-scale fabrication of ordered nanostructures is important for multiple applications in photonics and biomedicine including optical filters, solar cells, plasmonic biosensors, and DNA sequencing. Existing methods are either expensive or have strict limitations on the feature size and fabrication complexity. Here, we present a laser-based technique, plasmonic nanoparticle lithography, which is capable of rapid fabrication of large-scale arrays of sub-50 nm holes on various substrates. It is based on near-field enhancement and melting induced under ordered arrays of plasmonic nanoparticles, which are brought into contact or in close proximity to a desired material and acting as optical near-field lenses. The nanoparticles are arranged in ordered patterns on a flexible substrate and can be attached and removed from the patterned sample surface. At optimized laser fluence, the nanohole patterning process does not create any observable changes to the nanoparticles and they have been applied multiple times as reusable near-field masks. This resist-free nanolithography technique provides a simple and cheap solution for large-scale nanofabrication.

  20. Relationship between Peeled Internal Limiting Membrane Area and Anatomic Outcomes following Macular Hole Surgery: A Quantitative Analysis

    Directory of Open Access Journals (Sweden)

    Yasin Sakir Goker

    2016-01-01

    Full Text Available Purpose. To quantitatively evaluate the effects of peeled internal limiting membrane (ILM area and anatomic outcomes following macular hole surgery using spectral domain optical coherence tomography (SD-OCT. Methods. Forty-one eyes in 37 consecutive patients with idiopathic, Gass stage 3-4 macular hole (MH were enrolled in this retrospective comparative study. All patients were divided into 2 groups according to anatomic success or failure. Basal MH diameter, peeled ILM area, and MH height were calculated using SD-OCT. Other prognostic parameters, including age, stage, preoperative BCVA, and symptom duration were also assessed. Results. Thirty-two cases were classified as anatomic success, and 9 cases were classified as anatomic failure. Peeled ILM area was significantly wider and MH basal diameter was significantly less in the anatomic success group (p=0.024 and 0.032, resp.. Other parameters did not demonstrate statistical significance. Conclusion. The findings of the present study show that the peeled ILM area can affect the anatomic outcomes of MH surgery.

  1. Fouling Resilient Perforated Feed Spacers for Membrane Filtration

    KAUST Repository

    Kerdi, Sarah

    2018-04-24

    The improvement of feed spacers with optimal geometry remains a key challenge for spiral-wound membrane systems in water treatment due to their impact on the hydrodynamic performance and fouling development. In this work, novel spacer designs are proposed by intrinsically modifying cylindrical filaments through perforations. Three symmetric perforated spacers (1-Hole, 2-Hole, and 3-Hole) were in-house 3D-printed and experimentally evaluated in terms of permeate flux, feed channel pressure drop and membrane fouling. Spacer performance is characterized and compared with standard no perforated (0-Hole) design under constant feed pressure and constant feed flow rate. Perforations in the spacer filaments resulted in significantly lowering the net pressure drop across the spacer filled channel. The 3-Hole spacer was found to have the lowest pressure drop (50% - 61%) compared to 0-Hole spacer for various average flow velocities. Regarding permeate flux production, the 0-Hole spacer produced 5.7 L.m-2.h-1 and 6.6 L.m-2.h-1 steady state flux for constant pressure and constant feed flow rate, respectively. The 1-Hole spacer was found to be the most efficient among the perforated spacers with 75% and 23% increase in permeate production at constant pressure and constant feed flow, respectively. Furthermore, membrane surface of 1-Hole spacer was found to be cleanest in terms of fouling, contributing to maintain higher permeate flux production. Hydrodynamic understanding of these perforated spacers is also quantified by performing Direct Numerical Simulation (DNS). The performance enhancement of these perforated spacers is attributed to the formation of micro-jets in the spacer cell that aided in producing enough unsteadiness/turbulence to clean the membrane surface and mitigate fouling phenomena. In the case of 1-Hole spacer, the unsteadiness intensity at the outlet of micro-jets and the shear stress fluctuations created inside the cells are higher than those observed with

  2. Fouling resilient perforated feed spacers for membrane filtration.

    Science.gov (United States)

    Kerdi, Sarah; Qamar, Adnan; Vrouwenvelder, Johannes S; Ghaffour, Noreddine

    2018-04-24

    The improvement of feed spacers with optimal geometry remains a key challenge for spiral-wound membrane systems in water treatment due to their impact on the hydrodynamic performance and fouling development. In this work, novel spacer designs are proposed by intrinsically modifying cylindrical filaments through perforations. Three symmetric perforated spacers (1-Hole, 2-Hole, and 3-Hole) were in-house 3D-printed and experimentally evaluated in terms of permeate flux, feed channel pressure drop and membrane fouling. Spacer performance is characterized and compared with standard no perforated (0-Hole) design under constant feed pressure and constant feed flow rate. Perforations in the spacer filaments resulted in significantly lowering the net pressure drop across the spacer filled channel. The 3-Hole spacer was found to have the lowest pressure drop (50%-61%) compared to 0-Hole spacer for various average flow velocities. Regarding permeate flux production, the 0-Hole spacer produced 5.7 L m -2 .h -1 and 6.6 L m -2 .h -1 steady state flux for constant pressure and constant feed flow rate, respectively. The 1-Hole spacer was found to be the most efficient among the perforated spacers with 75% and 23% increase in permeate production at constant pressure and constant feed flow, respectively. Furthermore, membrane surface of 1-Hole spacer was found to be cleanest in terms of fouling, contributing to maintain higher permeate flux production. Hydrodynamic understanding of these perforated spacers is also quantified by performing Direct Numerical Simulation (DNS). The performance enhancement of these perforated spacers is attributed to the formation of micro-jets in the spacer cell that aided in producing enough unsteadiness/turbulence to clean the membrane surface and mitigate fouling phenomena. In the case of 1-Hole spacer, the unsteadiness intensity at the outlet of micro-jets and the shear stress fluctuations created inside the cells are higher than those

  3. Morphision: A method for subjective evaluation of metamorphopsia in patients with unilateral macular pathology (i.e., full thickness macular hole and epiretinal membrane

    Directory of Open Access Journals (Sweden)

    Marta Ugarte

    2013-01-01

    Full Text Available Background: Lack of clinical tests to quantify spatial components of distortion in patients with full thickness macular holes (FTMH and epiretinal membranes (ERM. Aim: To develop a test for subjective evaluation of visual distortion in the central visual field around fixation in patients with unilateral FTMH or ERM. Settings and Design: Prospective case-control study carried out at tertiary referral center. Materials and Methods: Twenty-five patients with unilateral macular disease (13 macular epiretinal membranes, 12 full-thickness macular holes, and nine controls (without ocular pathology underwent ophthalmological examination with logMAR ETDRS visual acuity, near vision and contrast sensitivity assessed. Macular optical coherence tomography and metamorphopsia assessment using Morphision test was also carried out. This test consists of a set of modified Amsler charts for detection, identification, and subjective quantification of visual distortion in the central visual field around fixation. Morphision test content and construct validity, and reliability (test-retest method were evaluated. Sixteen patients completed an unstructured survey on test performance and preference. Results: Every patient with unilateral FTMH or ERM identified a particular chart using Morphision test (content validity. None of the normal subjects without symptoms of metamorphopsia identified any distortion (construct validity. Test-retest showed a 100% consistency for frequency and 67% for amplitude. The mean amplitude difference between measurements was 0.02 degrees (SD = 0.038. The coefficient of repeatability was 0.075. There was a correlation between Morphision amplitude score and visual acuity and contrast sensitivity, individually. Conclusions: Morphision test allowed detection and subjective quantification of metamorphopsia in the clinical setting in our patients with unilateral macular epiretinal membranes and full thickness macular holes.

  4. [Functional and Anatomic Outcomes of Primary and Secondary Internal Limiting Membrane Transplantation in Large and Persistent Macular Holes].

    Science.gov (United States)

    Hess, Jelka A; Michels, Stephan; Becker, Matthias D

    2017-11-20

    Background The gold standard therapy for full-thickness macular holes (FTMH) is vitrectomy (PPV) with peeling of the internal limiting membrane (ILM), gas tamponade of the vitreous cavity and postoperative face-down positioning. Nevertheless, eyes with large macular holes (> 400 µm) and surgical failures remain difficult to manage. Recently, ILM transplantation (ILM-TX) techniques were developed with acceptable results, advocating different mechanisms of hole closure: in such a setting, the ILM could serve as a scaffold for neuronal tissue in the pedicle ILM flap technique or the ILM could induce a contraction of the FTMH rims through shrinking of a folded ILM plug. Patients/Material and Methods This retrospective study evaluates the functional and anatomic outcomes following ILM-TX for large FTMH and failed FMTH surgery. Large holes (group 1) were treated by the pedicle flap and the plug technique. Persistent holes following vitrectomy and ILM peeling (group 2) were treated with the plug technique. All ILM-TX were performed under perfluorocarbon liquid (PFCL) with a subsequent silicone oil tamponade. Results In group 1 (6 eyes), three eyes had a free ILM graft and three eyes underwent a pedunculated ILM-TX. The mean best corrected visual acuity (BCVA, LogMar) before primary ILM-TX was 1.18 ± 0.54 with a mean initial hole size of 681 ± 106 µm and a photoreceptor defect (PRD) of 1829 ± 474 µm. Five of six eyes showed a postoperative anatomical macular hole closure (83%). The mean BCVA after a mean follow-up of 9.3 ± 5.1 months was 0.83 ± 0.31 after a free ILM graft and 0.95 ± 0.79 after a pedunculated ILM flap. The PRD reduced to 1781 ± 713 µm after a free ILM graft and 1148 ± 378 µm after a pedunculated ILM flap. In group 2 (7 eyes), all patients had failed initial macular hole surgery closure. Prior to free ILM-TX BCVA was 1.05 ± 0.41, the hole size was 433 ± 183 µm and PRD was 2012 ± 718

  5. Inkjet printing of nanoporous gold electrode arrays on cellulose membranes for high-sensitive paper-like electrochemical oxygen sensors using ionic liquid electrolytes.

    Science.gov (United States)

    Hu, Chengguo; Bai, Xiaoyun; Wang, Yingkai; Jin, Wei; Zhang, Xuan; Hu, Shengshui

    2012-04-17

    A simple approach to the mass production of nanoporous gold electrode arrays on cellulose membranes for electrochemical sensing of oxygen using ionic liquid (IL) electrolytes was established. The approach, combining the inkjet printing of gold nanoparticle (GNP) patterns with the self-catalytic growth of these patterns into conducting layers, can fabricate hundreds of self-designed gold arrays on cellulose membranes within several hours using an inexpensive inkjet printer. The resulting paper-based gold electrode arrays (PGEAs) had several unique properties as thin-film sensor platforms, including good conductivity, excellent flexibility, high integration, and low cost. The porous nature of PGEAs also allowed the addition of electrolytes from the back cellulose membrane side and controllably produced large three-phase electrolyte/electrode/gas interfaces at the front electrode side. A novel paper-based solid-state electrochemical oxygen (O(2)) sensor was therefore developed using an IL electrolyte, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF(6)). The sensor looked like a piece of paper but possessed high sensitivity for O(2) in a linear range from 0.054 to 0.177 v/v %, along with a low detection limit of 0.0075% and a short response time of less than 10 s, foreseeing its promising applications in developing cost-effective and environment-friendly paper-based electrochemical gas sensors.

  6. Sulfonated Holey Graphene Oxide (SHGO) Filled Sulfonated Poly(ether ether ketone) Membrane: The Role of Holes in the SHGO in Improving Its Performance as Proton Exchange Membrane for Direct Methanol Fuel Cells.

    Science.gov (United States)

    Jiang, Zhong-Jie; Jiang, Zhongqing; Tian, Xiaoning; Luo, Lijuan; Liu, Meilin

    2017-06-14

    Sulfonated holey graphene oxides (SHGOs) have been synthesized by the etching of sulfonated graphene oxides with concentrated HNO 3 under the assistance of ultrasonication. These SHGOs could be used as fillers for the sulfonated aromatic poly(ether ether ketone) (SPEEK) membrane. The obtained SHGO-incorporated SPEEK membrane has a uniform and dense structure, exhibiting higher performance as proton exchange membranes (PEMs), for instance, higher proton conductivity, lower activation energy for proton conduction, and comparable methanol permeability, as compared to Nafion 112. The sulfonated graphitic structure of the SHGOs is believed to be one of the crucial factors resulting in the higher performance of the SPEEK/SHGO membrane, since it could increase the local density of the -SO 3 H groups in the membrane and induce a strong interfacial interaction between SHGO and the SPEEK matrix, which improve the proton conductivity and lower the swelling ratio of the membrane, respectively. Additionally, the proton conductivity of the membrane could be further enhanced by the presence of the holes in the graphitic planes of the SHGOs, since it provides an additional channel for transport of the protons. When used, direct methanol fuel cell with the SPEEK/SHGO membrane is found to exhibit much higher performance than that with Nafion 112, suggesting potential use of the SPEEK/SHGO membrane as the PEMs.

  7. Sensitivity of GRETINA position resolution to hole mobility

    Energy Technology Data Exchange (ETDEWEB)

    Prasher, V.S. [Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Cromaz, M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Merchan, E.; Chowdhury, P. [Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Crawford, H.L. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lister, C.J. [Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States); Campbell, C.M.; Lee, I.Y.; Macchiavelli, A.O. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Radford, D.C. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wiens, A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2017-02-21

    The sensitivity of the position resolution of the gamma-ray tracking array GRETINA to the hole charge-carrier mobility parameter is investigated. The χ{sup 2} results from a fit of averaged signal (“superpulse”) data exhibit a shallow minimum for hole mobilities 15% lower than the currently adopted values. Calibration data on position resolution is analyzed, together with simulations that isolate the hole mobility dependence of signal decomposition from other effects such as electronics cross-talk. The results effectively exclude hole mobility as a dominant parameter for improving the position resolution for reconstruction of gamma-ray interaction points in GRETINA.

  8. Polymer microcapsules with "foamed" membranes.

    Science.gov (United States)

    Lavergne, Fleur-Marie; Cot, Didier; Ganachaud, François

    2007-06-05

    This article describes the preparation of capsules displaying craters at their surfaces and independent holes inside their membranes. These poly(methylmethacrylate) capsules of 20 to 200 microm diameter are prepared by a solvent evaporation process and typically contain a dispersant, polyvinyl alcohol, and an excipient, namely, a fatty acid triglyceride (miglyol 812). Spectroscopic methods showed that, depending on the miglyol content, the craters at the surface exhibited sizes of about 1 to 2 microm, whereas the core structure of the membrane changed significantly, typically from "soft-part-of-bread" up to "foamed"-like aspects. Among several spectroscopy techniques, confocal fluorescence microscopy confirmed that the capsules retained the miglyol in their core and not in the craters or holes, even after centrifugation and handling. This technique also showed that holes in the membrane are filled with water. A possible analysis of the "foaming" phenomenon based on the surface tensions of different oils, as well as their optimal hydrophile-lipophile balance (HLBO), is added to generalize the concept.

  9. Diode-like properties of single- and multi-pore asymmetric track membranes

    Science.gov (United States)

    Zielinska, K.; Gapeeva, A. R.; Orelovich, O. L.; Apel, P. Yu.

    2014-05-01

    In this work, we investigated the ionic transport properties of asymmetric polyethylene terephthalate (PET) track membranes with the thickness of 5 μm. The samples containing single pores and arrays of many pores were fabricated by irradiation with accelerated ions and subsequent physicochemical treatment. The method of etching in the presence of a surface-active agent was used to prepare the pores with highly-tapered tip. The transport of monovalent inorganic ions through the nano-scale holes was studied in a conductivity cell. The effective pore radii, electrical conductance and rectification ratios of pores were measured. The geometric characteristics of nanopores were investigated using FESEM.

  10. miRNAs in the vitreous humor of patients affected by idiopathic epiretinal membrane and macular hole.

    Directory of Open Access Journals (Sweden)

    Andrea Russo

    Full Text Available The aim of the present study was to assess the expression of miRNAs in the Vitreous Humor (VH of patients with Macular Hole (MH and Epiretinal Membrane (ERM compared to a control group.In this prospective, comparative study, 2-ml of VH was extracted from the core of the vitreous chamber in consecutive patients who underwent standard vitrectomy for ERM and MH. RNA was extracted and TaqMan® Low Density Arrays (TLDAs were used to profile the transcriptome of 754 miRNAs. Results were validated by single TaqMan® assays. Finally, we created a biological network of differentially expressed miRNA targets and their nearest neighbors.Overall 10 eyes with MH, 16 eyes with idiopathic ERM and 6 controls were enrolled in the study. Profiling data identified 5 miRNAs differentially expressed in patients affected by MH and ERM with respect to controls. Four were downregulated (miR-19b, miR-24, miR-155, miR-451 and 1 was downregulated (miR-29a; TaqMan® assays of the VH of patients affected by MH and ERM, with respect to controls, showed that the most differentially expressed were miR-19b (FC -9.13, p:<0.00004, mir-24 (FC -7.52, p:<0.004 and miR-142-3p (FC -5.32, p:<0.011. Our network data showed that deregulation of differentially expressed miRNAs induces an alteration of several pathways associated with genes involved in both MH and ERM.The present study suggests that disregulation of miR-19b, miR-24 and miR-142-3p, might be related to the alterations that characterize patients affected by MH and ERM.

  11. Flux studies on ion microporous membrane for the use of medical filtration

    International Nuclear Information System (INIS)

    Guo Hongying; Huang Zhengde

    2002-01-01

    The influences of the irradiating condition (divergent and perpendicular irradiation) and hole shapes (cylinder and cone holes) on the flux are studied for ion microporous membrane. The results show that divergent irradiation and cone hole both can improve the flux of ion microporous membrane for the use of medical filtration

  12. Black Holes Have Simple Feeding Habits

    Science.gov (United States)

    2008-06-01

    properties of these black holes should be very helpful. In addition to Chandra, three radio arrays (the Giant Meterwave Radio Telescope, the Very Large Array and the Very Long Baseline Array), two millimeter telescopes (the Plateau de Bure Interferometer and the Submillimeter Array), and Lick Observatory in the optical were used to monitor M81. These observations were made simultaneously to ensure that brightness variations because of changes in feeding rates did not confuse the results. Chandra is the only X-ray satellite able to isolate the faint X-rays of the black hole from the emission of the rest of the galaxy. This result confirms less detailed earlier work by Andrea Merloni from the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany and colleagues that suggested that the basic properties of larger black holes are similar to the smaller ones. Their study, however, was not based on simultaneous, multi-wavelength observations nor the application of a detailed physical model. These results will appear in an upcoming issue of The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

  13. A grating coupler with a trapezoidal hole array for perfectly vertical light coupling between optical fibers and waveguides

    Science.gov (United States)

    Mizutani, Akio; Eto, Yohei; Kikuta, Hisao

    2017-12-01

    A grating coupler with a trapezoidal hole array was designed and fabricated for perfectly vertical light coupling between a single-mode optical fiber and a silicon waveguide on a silicon-on-insulator (SOI) substrate. The grating coupler with an efficiency of 53% was computationally designed at a 1.1-µm-thick buried oxide (BOX) layer. The grating coupler and silicon waveguide were fabricated on the SOI substrate with a 3.0-µm-thick BOX layer by a single full-etch process. The measured coupling efficiency was 24% for TE-polarized light at 1528 nm wavelength, which was 0.69 times of the calculated coupling efficiency for the 3.0-µm-thick BOX layer.

  14. Stationary black holes: large D analysis

    International Nuclear Information System (INIS)

    Suzuki, Ryotaku; Tanabe, Kentaro

    2015-01-01

    We consider the effective theory of large D stationary black holes. By solving the Einstein equations with a cosmological constant using the 1/D expansion in near zone of the black hole we obtain the effective equation for the stationary black hole. The effective equation describes the Myers-Perry black hole, bumpy black holes and, possibly, the black ring solution as its solutions. In this effective theory the black hole is represented as an embedded membrane in the background, e.g., Minkowski or Anti-de Sitter spacetime and its mean curvature is given by the surface gravity redshifted by the background gravitational field and the local Lorentz boost. The local Lorentz boost property of the effective equation is observed also in the metric itself. In fact we show that the leading order metric of the Einstein equation in the 1/D expansion is generically regarded as a Lorentz boosted Schwarzschild black hole. We apply this Lorentz boost property of the stationary black hole solution to solve perturbation equations. As a result we obtain an analytic formula for quasinormal modes of the singly rotating Myers-Perry black hole in the 1/D expansion.

  15. Yield surfaces for perforated plates with square arrays of holes

    International Nuclear Information System (INIS)

    Bhattacharya, A.; Venkat Raj, V.

    2004-01-01

    A symmetric model of a perforated plate containing a 3x3 array of circular holes, arranged in a square pattern, was chosen and elastoplastic finite element analyses were carried out to determine the limit stresses for both pitch and diagonal directions of loading, for different values of biaxiality ratios. Plane stress conditions were assumed and the Tresca and von Mises yield criteria were employed to obtain two different sets of results. Yield surfaces were constructed and 'general cut-out factors' were determined for four different ligament efficiencies. The FEM results obtained by the authors using the Tresca and von Mises yield criteria were compared with the corresponding results of [J. Pressure Vessel Technol. Trans. ASME (1975) 146-154] and [J. Pressure Vessel Technol. Trans. ASME (1997) 122-126], respectively. The results based on the Tresca yield criterion obtained by the present authors and those in [J. Pressure Vessel Technol. Trans. ASME (1975) 146-154] were found to agree well with each other. In the case of the von Mises yield criterion, the agreement with [J. Pressure Vessel Technol. Trans. ASME 122-126] is generally good. The estimates based on the Tresca yield criterion are seen to result in lower values of limit stresses and cut-out factors as compared to those based on the von Mises yield criterion. The difference is attributed to the yield criterion and the flow rule chosen for the analysis. The shape as well as the size of the yield surface was found to depend on the ligament efficiency

  16. Testing the membrane paradigm with holography

    NARCIS (Netherlands)

    de Boer, J.; Heller, M.P.; Pinzani-Fokeeva, N.

    2015-01-01

    One version of the membrane paradigm states that, as far as outside observers are concerned, black holes can be replaced by a dissipative membrane with simple physical properties located at the stretched horizon. We demonstrate that such a membrane paradigm is incomplete in several aspects. We argue

  17. Development of an automation technique for the establishment of functional lipid bilayer arrays

    International Nuclear Information System (INIS)

    Hansen, J S; Vogel, J; Geschke, O; Emnéus, J; Nielsen, C H; Perry, M; Vissing, T; Hansen, C R

    2009-01-01

    In the present work, a technique for establishing multiple black lipid membranes (BLMs) in arrays of micro structured ethylene tetrafluoroethylene (ETFE) films, and supported by a micro porous material was developed. Rectangular 8 × 8 arrays with apertures having diameters of 301 ± 5 µm were fabricated in ETFE Teflon film by laser ablation using a carbon dioxide laser. Multiple lipid membranes could be formed across the micro structured 8 × 8 array ETFE partitions. Success rates for the establishment of cellulose-supported BLMs across the multiple aperture arrays were above 95%. However, the time course of the membrane thinning process was found to vary considerably between multiple aperture bilayer experiments. An airbrush partition pretreatment technique was developed to increase the reproducibility of the multiple lipid bilayers formation during the time course from the establishment of the lipid membranes to the formation of bilayers. The results showed that multiple lipid bilayers could be reproducible formed across the airbrush-pretreated 8 × 8 rectangular arrays. The ionophoric peptide valinomycin was incorporated into established membrane arrays, resulting in ionic currents that could be effectively blocked by tetraethylammonium. This shows that functional bimolecular lipid membranes were established, and furthermore outlines that the established lipid membrane arrays could host functional membrane-spanning molecules

  18. Realization of a 33 GHz phononic crystal fabricated in a freestanding membrane

    Directory of Open Access Journals (Sweden)

    Drew F. Goettler

    2011-12-01

    Full Text Available Phononic crystals (PnCs are man-made structures with periodically varying material properties such as density, ρ, and elastic modulus, E. Periodic variations of the material properties with nanoscale characteristic dimensions yield PnCs that operate at frequencies above 10 GHz, allowing for the manipulation of thermal properties. In this article, a 2D simple cubic lattice PnC operating at 33 GHz is reported. The PnC is created by nanofabrication with a focused ion beam. A freestanding membrane of silicon is ion milled to create a simple cubic array of 32 nm diameter holes that are subsequently backfilled with tungsten to create inclusions at a spacing of 100 nm. Simulations are used to predict the operating frequency of the PnC. Additional modeling shows that milling a freestanding membrane has a unique characteristic; the exit via has a conical shape, or trumpet-like appearance.

  19. Efficacy of vitrectomy with triamcinolone assistance versus internal limiting membrane peeling for highly myopic macular hole retinal detachment.

    Science.gov (United States)

    Wei, Yong; Wang, Ningli; Zu, Zhongqiao; Bi, Chuncao; Wang, Huaizhou; Chen, Fenghua; Yang, Xingguang

    2013-06-01

    To compare the outcomes of pars plana vitrectomy (PPV) with or without the adjuvant surgical procedures: triamcinolone acetonide (TA) assistance and/or internal limiting membrane (ILM) peeling for the treatment of highly myopic macular hole retinal detachment (MHRD). Case-control study. Pars plana vitrectomy combined with 2 kinds of adjuvant surgical procedures were used on 96 highly myopic eyes with MHRD. These eyes were assigned to 4 groups randomly: Group 1, non-TA-assisted PPV and without ILM peeling; Group 2, non-TA-assisted PPV with ILM peeling; Group 3, TA-assisted PPV and without ILM peeling; Group 4, TA-assisted PPV with ILM peeling. Anatomical reattachment of the retina, macular hole closure, and best-corrected visual acuity were measured. The rates of both retinal reattachment and macular hole closure were higher in Group 2 (84.0 and 44.0%) and Group 3 (80.8 and 46.2%) than Group 1 (73.9 and 17.4%); however, there were no differences between Group 2 and Group 3 (P > 0.05). The rates of macular hole closure were extremely low in Group 1 and also in eyes with extreme long axial lengths (≥29.0 mm), "severe" chorioretinal atrophy, and posterior staphyloma. Pars plana vitrectomy with either TA assistance or ILM peeling was effective for the treatment of highly myopic MHRD. If you peel the ILM, adding TA does not affect closure rates; and if TA is used to visualize the vitreous, ILM peeling may not be necessary in MHRD. There was a lower anatomical success rate in MHRD with extreme long axial lengths, severe chorioretinal atrophy, and posterior staphyloma.

  20. Piezoelectric transducer array microspeaker

    KAUST Repository

    Carreno, Armando Arpys Arevalo; Conchouso Gonzalez, David; Castro, David; Kosel, Jü rgen; Foulds, Ian G.

    2016-01-01

    contains 2n piezoelectric transducer membranes, where “n” is the bit number. Every element of the array has a circular shape structure. The membrane is made out four layers: 300nm of platinum for the bottom electrode, 250nm or lead zirconate titanate (PZT

  1. Cationic nanoparticles induce nanoscale disruption in living cell plasma membranes.

    Science.gov (United States)

    Chen, Jiumei; Hessler, Jessica A; Putchakayala, Krishna; Panama, Brian K; Khan, Damian P; Hong, Seungpyo; Mullen, Douglas G; Dimaggio, Stassi C; Som, Abhigyan; Tew, Gregory N; Lopatin, Anatoli N; Baker, James R; Holl, Mark M Banaszak; Orr, Bradford G

    2009-08-13

    It has long been recognized that cationic nanoparticles induce cell membrane permeability. Recently, it has been found that cationic nanoparticles induce the formation and/or growth of nanoscale holes in supported lipid bilayers. In this paper, we show that noncytotoxic concentrations of cationic nanoparticles induce 30-2000 pA currents in 293A (human embryonic kidney) and KB (human epidermoid carcinoma) cells, consistent with a nanoscale defect such as a single hole or group of holes in the cell membrane ranging from 1 to 350 nm(2) in total area. Other forms of nanoscale defects, including the nanoparticle porating agents adsorbing onto or intercalating into the lipid bilayer, are also consistent; although the size of the defect must increase to account for any reduction in ion conduction, as compared to a water channel. An individual defect forming event takes 1-100 ms, while membrane resealing may occur over tens of seconds. Patch-clamp data provide direct evidence for the formation of nanoscale defects in living cell membranes. The cationic polymer data are compared and contrasted with patch-clamp data obtained for an amphiphilic phenylene ethynylene antimicrobial oligomer (AMO-3), a small molecule that is proposed to make well-defined 3.4 nm holes in lipid bilayers. Here, we observe data that are consistent with AMO-3 making approximately 3 nm holes in living cell membranes.

  2. X-ray focusing using capillary arrays

    International Nuclear Information System (INIS)

    Nugent, K.A.; Chapman, H.N.

    1990-01-01

    A new form of X-ray focusing device based on glass capillary arrays is presented. Theoretical and experimental results for array of circular capillaries and theoretical and computational results for square hole capillaries are given. It is envisaged that devices such as these will find wide applications in X-ray optics as achromatic condensers and collimators. 3 refs., 4 figs

  3. Efficient photocatalytic degradation of gaseous N,N-dimethylformamide in tannery waste gas using doubly open-ended Ag/TiO2 nanotube array membranes

    Science.gov (United States)

    Zhao, Yang; Ma, Lin; Chang, Wenkai; Huang, Zhiding; Feng, Xugen; Qi, Xiaoxia; Li, Zenghe

    2018-06-01

    Gaseous N,N-dimethylformamide (DMF), typical volatile organic compound exhausted from manufacturing factories, may damage the health of workers under long-term exposure even at low levels. The defined geometry, porous surface and highly ordered channels make the free-standing anodic TiO2 nanotube (TiNT) arrays particularly suitable for applications of practical air purification by flow-through photocatalysis. In the present work, crystallized doubly open-ended Ag/TiNT array membranes were designed and prepared by employing a lift-off process based on an anodization-annealing-anodization-etching sequence, followed by uniform Ag nanoparticles decoration. For the photocatalytic degradation of gaseous DMF at low concentration levels close to that found in realistic pollutant air, an analytical methodology for the monitoring and determination of degradation process was developed based on the coupling of headspace sampling with gas chromatography mass spectrometry (HS-GC-MS). The doubly open-ended Ag/TiNT arrays exhibited higher removal efficiency of gaseous DMF from air compared with conventional bottom-closed Ag/TiNT arrays and pure bottomless TiNT arrays. These results indicated that the photocatalytic properties of TiNT arrays were improved with the open-bottom morphology and the Ag nanoparticles decoration. Based on the analysis with GC-MS and high performance ion chromatography (HPIC), it was found that demethylation is the main pathway of DMF degradation in photocatalytic reactions. Furthermore, decontamination of actual polluted tannery waste gas collected in leather factory proved that the photocatalysis on doubly open-ended Ag/TiNT array membrane is an efficient way and a promising application to treat air contaminated by DMF despite the complexity of various volatile organic compounds.

  4. Incidence and causes of iatrogenic retinal breaks in idiopathic macular hole and epiretinal membrane.

    Science.gov (United States)

    Yagi, Fumihiko; Takagi, Seiji; Tomita, Goji

    2014-03-01

    To evaluate the incidence and cause of iatrogenic retinal breaks (RBs) and postoperative retinal detachment (RD) in cases of idiopathic macular hole (MH) and epiretinal membrane (ERM). We analyzed 79 eyes with MH and 41 eyes with ERM, the relationship between the incidence of RBs and RD, and the frequency of posterior vitreous detachment (PVD) and lattice degeneration (LD). The incidence of RBs related to the operation was significantly higher in eyes with MH. The frequency of PVD was significantly higher in eyes with ERM. The frequency of LD did not differ between groups. In the MH group, the incidence of RBs related to the operation was high in eyes without PVD, but with LD. We observed four cases of RD in the MH group. The MH group had higher incidence of RBs related to the operation, especially in eyes without PVD or with LD.

  5. Layer-by-layer cell membrane assembly

    Science.gov (United States)

    Matosevic, Sandro; Paegel, Brian M.

    2013-11-01

    Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

  6. Formation of precise 2D Au particle arrays via thermally induced dewetting on pre-patterned substrates

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2011-06-01

    Full Text Available The fabrication of precise 2D Au nanoparticle arrays over a large area is presented. The technique was based on pre-patterning of the substrate before the deposition of a thin Au film, and the creation of periodic particle arrays by subsequent dewetting induced by annealing. Two types of pre-patterned substrates were used: The first comprised an array of pyramidal pits and the second an array of circular holes. For the dewetting of Au films on the pyramidal pit substrate, the structural curvature-driven diffusion cooperates with capillarity-driven diffusion, resulting in the formation of precise 2D particle arrays for films within a structure dependent thickness-window. For the dewetting of Au films on the circular hole substrate, the periodic discontinuities in the films, induced by the deposition, can limit the diffusion paths and lead to the formation of one particle per individual separated region (holes or mesas between holes, and thus, result in the evolution of precise 2D particle arrays. The influence of the pre-patterned structures and the film thickness is analyzed and discussed. For both types of pre-patterned substrate, the Au film thickness had to be adjusted in a certain thickness-window in order to achieve the precise 2D particle arrays.

  7. Formation of precise 2D Au particle arrays via thermally induced dewetting on pre-patterned substrates

    Science.gov (United States)

    Ji, Ran

    2011-01-01

    Summary The fabrication of precise 2D Au nanoparticle arrays over a large area is presented. The technique was based on pre-patterning of the substrate before the deposition of a thin Au film, and the creation of periodic particle arrays by subsequent dewetting induced by annealing. Two types of pre-patterned substrates were used: The first comprised an array of pyramidal pits and the second an array of circular holes. For the dewetting of Au films on the pyramidal pit substrate, the structural curvature-driven diffusion cooperates with capillarity-driven diffusion, resulting in the formation of precise 2D particle arrays for films within a structure dependent thickness-window. For the dewetting of Au films on the circular hole substrate, the periodic discontinuities in the films, induced by the deposition, can limit the diffusion paths and lead to the formation of one particle per individual separated region (holes or mesas between holes), and thus, result in the evolution of precise 2D particle arrays. The influence of the pre-patterned structures and the film thickness is analyzed and discussed. For both types of pre-patterned substrate, the Au film thickness had to be adjusted in a certain thickness-window in order to achieve the precise 2D particle arrays. PMID:21977445

  8. Retinal thickness after vitrectomy and internal limiting membrane peeling for macular hole and epiretinal membrane

    Science.gov (United States)

    Kumagai, Kazuyuki; Ogino, Nobuchika; Furukawa, Mariko; Hangai, Masanori; Kazama, Shigeyasu; Nishigaki, Shirou; Larson, Eric

    2012-01-01

    Purpose To determine the retinal thickness (RT), after vitrectomy with internal limiting membrane (ILM) peeling, for an idiopathic macular hole (MH) or an epiretinal membrane (ERM). Also, to investigate the effect of a dissociated optic nerve fiber layer (DONFL) appearance on RT. Methods A non-randomized, retrospective chart review was performed for 159 patients who had successful closure of a MH, with (n = 148), or without (n = 11), ILM peeling. Also studied were 117 patients who had successful removal of an ERM, with (n = 104), or without (n = 13), ILM peeling. The RT of the nine Early Treatment Diabetic Retinopathy Study areas was measured by spectral domain optical coherence tomography (SD-OCT). In the MH-with-ILM peeling and ERM-with-ILM peeling groups, the RT of the operated eyes was compared to the corresponding areas of normal fellow eyes. The inner temporal/inner nasal ratio (TNR) was used to assess the effect of ILM peeling on RT. The effects of DONFL appearance on RT were evaluated in only the MH-with-ILM peeling group. Results In the MH-with-ILM peeling group, the central, inner nasal, and outer nasal areas of the retina of operated eyes were significantly thicker than the corresponding areas of normal fellow eyes. In addition, the inner temporal, outer temporal, and inner superior retina was significantly thinner than in the corresponding areas of normal fellow eyes. Similar findings were observed regardless of the presence of a DONFL appearance. In the ERM-with-ILM peeling group, the retina of operated eyes was significantly thicker in all areas, except the inner and outer temporal areas. In the MH-with-ILM peeling group, the TNR was 0.86 in operated eyes, and 0.96 in fellow eyes (P peeling group, the TNR was 0.84 in operated eyes, and 0.95 in fellow eyes (P peeling group was 0.98, which was significantly greater than that of the MH-with-ILM peeling group (P peeling group was 0.98, which was significantly greater than that of ERM-with-ILM peeling

  9. Quantum statistical entropy for Kerr-de Sitter black hole

    Institute of Scientific and Technical Information of China (English)

    Zhang Li-Chun; Wu Yue-Qin; Zhao Ren

    2004-01-01

    Improving the membrane model by which the entropy of the black hole is studied, we study the entropy of the black hole in the non-thermal equilibrium state. To give the problem stated here widespread meaning, we discuss the (n+2)-dimensional de Sitter spacetime. Through discussion, we obtain that the black hole's entropy which contains two horizons (a black hole's horizon and a cosmological horizon) in the non-thermal equilibrium state comprises the entropy corresponding to the black hole's horizon and the entropy corresponding to the cosmological horizon. Furthermore, the entropy of the black hole is a natural property of the black hole. The entropy is irrelevant to the radiation field out of the horizon. This deepens the understanding of the relationship between black hole's entropy and horizon's area. A way to study the bosonic and fermionic entropy of the black hole in high non-thermal equilibrium spacetime is given.

  10. ZnTe Amorphous Semiconductor Nanowires Array Electrodeposited into Polycarbonate Membrane Thin Films

    International Nuclear Information System (INIS)

    Ohgai, T; Ikeda, T; Ohta, J

    2013-01-01

    ZnTe amorphous semiconductor nanowires array was electrodeposited into the nanochannels of ion-track etched polycarbonate membrane thin films from acidic aqueous solution at 313 K. ZnTe electrodeposits with Zn-rich composition was obtained over the wide range of cathode potential from −0.8 V to −1.1 V and the growth rate of ZnTe amorphous nanowires was around 3 nm.sec −1 at the cathode potential of −0.8 V. Cylindrical shape of the nanowires was precisely transferred from the nanochannels and the aspect ratio reached up to ca. 40. ZnTe amorphous phase electrodeposited at 313 K was crystallized by annealing at 683 K and the band gap energy of ZnTe crystalline phase reached up to ca. 2.13 eV.

  11. Optimal management of idiopathic macular holes

    Directory of Open Access Journals (Sweden)

    Madi HA

    2016-01-01

    Full Text Available Haifa A Madi,1,* Ibrahim Masri,1,* David H Steel1,2 1Sunderland Eye Infirmary, Sunderland, 2Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle, UK *These authors contributed equally to this work Abstract: This review evaluates the current surgical options for the management of idiopathic macular holes (IMHs, including vitrectomy, ocriplasmin (OCP, and expansile gas use, and discusses key background information to inform the choice of treatment. An evidence-based approach to selecting the best treatment option for the individual patient based on IMH characteristics and patient-specific factors is suggested. For holes without vitreomacular attachment (VMA, vitrectomy is the only option with three key surgical variables: whether to peel the inner limiting membrane (ILM, the type of tamponade agent to be used, and the requirement for postoperative face-down posturing. There is a general consensus that ILM peeling improves primary anatomical hole closure rate; however, in small holes (<250 µm, it is uncertain whether peeling is always required. It has been increasingly recognized that long-acting gas and face-down positioning are not always necessary in patients with small- and medium-sized holes, but large (>400 µm and chronic holes (>1-year history are usually treated with long-acting gas and posturing. Several studies on posturing and gas choice were carried out in combination with ILM peeling, which may also influence the gas and posturing requirement. Combined phacovitrectomy appears to offer more rapid visual recovery without affecting the long-term outcomes of vitrectomy for IMH. OCP is licensed for use in patients with small- or medium-sized holes and VMA. A greater success rate in using OCP has been reported in smaller holes, but further predictive factors for its success are needed to refine its use. It is important to counsel patients realistically regarding the rates of success with

  12. Microwave Power for Smart Membrane Actuators

    Science.gov (United States)

    Choi, Sang H.; Song, Kyo D.; Golembiewski, Walter T.; Chu, Sang-Hyon; King, Glen C.

    2002-01-01

    The concept of microwave-driven smart membrane actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. A large, ultra-light space structure, such as solar sails and Gossamer spacecrafts, requires a distribution of power into individual membrane actuators to control them in an effective way. A patch rectenna array with a high voltage output was developed to drive smart membrane actuators. Networked patch rectenna array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is developed and tested for networking a rectenna/actuator patch array. For the future development, the PAD circuit could be imbedded into a single embodiment of rectenna and actuator array with the thin-film microcircuit embodiment. Preliminary design and fabrication of PAD circuitry that consists of a sixteen nodal elements were made for laboratory testing.

  13. Simple, Fast, and Cost-Effective Fabrication of Wafer-Scale Nanohole Arrays on Silicon for Antireflection

    Directory of Open Access Journals (Sweden)

    Di Di

    2014-01-01

    Full Text Available A simple, fast, and cost-effective method was developed in this paper for the high-throughput fabrication of nanohole arrays on silicon (Si, which is utilized for antireflection. Wafer-scale polystyrene (PS monolayer colloidal crystal was developed as templates by spin-coating method. Metallic shadow mask was prepared by lifting off the oxygen etched PS beads from the deposited chromium film. Nanohole arrays were fabricated by Si dry etching. A series of nanohole arrays were fabricated with the similar diameter but with different depth. It is found that the maximum depth of the Si-hole was determined by the diameter of the Cr-mask. The antireflection ability of these Si-hole arrays was investigated. The results show that the reflection decreases with the depth of the Si-hole. The deepest Si-hole arrays show the best antireflection ability (reflection 600 nm, which was about 28 percent of the nonpatterned silicon wafer’s reflection. The proposed method has the potential for high-throughput fabrication of patterned Si wafer, and the low reflectivity allows the application of these wafers in crystalline silicon solar cells.

  14. Stable micron-scale holes are a general feature of canonical holins.

    Science.gov (United States)

    Savva, Christos G; Dewey, Jill S; Moussa, Samir H; To, Kam H; Holzenburg, Andreas; Young, Ry

    2014-01-01

    At a programmed time in phage infection cycles, canonical holins suddenly trigger to cause lethal damage to the cytoplasmic membrane, resulting in the cessation of respiration and the non-specific release of pre-folded, fully active endolysins to the periplasm. For the paradigm holin S105 of lambda, triggering is correlated with the formation of micron-scale membrane holes, visible as interruptions in the bilayer in cryo-electron microscopic images and tomographic reconstructions. Here we report that the size distribution of the holes is stable for long periods after triggering. Moreover, early triggering caused by an early lysis allele of S105 formed approximately the same number of holes, but the lesions were significantly smaller. In contrast, early triggering prematurely induced by energy poisons resulted in many fewer visible holes, consistent with previous sizing studies. Importantly, the unrelated canonical holins P2 Y and T4 T were found to cause the formation of holes of approximately the same size and number as for lambda. In contrast, no such lesions were visible after triggering of the pinholin S(21) 68. These results generalize the hole formation phenomenon for canonical holins. A model is presented suggesting the unprecedentedly large size of these holes is related to the timing mechanism. © 2013 John Wiley & Sons Ltd.

  15. Displacement of fovea toward optic disk after macular hole surgery with internal limiting membrane peeling.

    Science.gov (United States)

    Ohta, Kouichi; Sato, Atsuko; Senda, Nami; Fukui, Emi

    2017-01-01

    The purpose of this study was to demonstrate a displacement of the foveal depression toward the optic disk after idiopathic macular hole (MH) surgery with internal limiting membrane (ILM) peeling. Two patients with a unilateral MH developed an MH in the fellow eyes. Vitrectomy with ILM peeling was performed on the fellow eye to close the MH. Images of spectral-domain optical coherence tomography (SD-OCT) were used to measure the disk-to-fovea distances pre MH formation, after MH formation, and 6 months after the closure of the MH. The disk-to-fovea distance was shorter at 6 months than after the development of the MH (4,109 µm and 4,174 µm in Case 1 and 4,001 µm and 4,051 µm in Case 2). These results indicate that the fovea moves nasally after the MH surgery with ILM peeling.

  16. How the antimicrobial peptides destroy bacteria cell membrane: Translocations vs. membrane buckling

    Science.gov (United States)

    Golubovic, Leonardo; Gao, Lianghui; Chen, Licui; Fang, Weihai

    2012-02-01

    In this study, coarse grained Dissipative Particle Dynamics simulation with implementation of electrostatic interactions is developed in constant pressure and surface tension ensemble to elucidate how the antimicrobial peptide molecules affect bilayer cell membrane structure and kill bacteria. We find that peptides with different chemical-physical properties exhibit different membrane obstructing mechanisms. Peptide molecules can destroy vital functions of the affected bacteria by translocating across their membranes via worm-holes, or by associating with membrane lipids to form hydrophilic cores trapped inside the hydrophobic domain of the membranes. In the latter scenario, the affected membranes are strongly corrugated (buckled) in accord with very recent experimental observations [G. E. Fantner et al., Nat. Nanotech., 5 (2010), pp. 280-285].

  17. Piezoelectric array elements for sound reconstruction with a digital input

    KAUST Repository

    Carreno, Armando Arpys Arevalo

    2016-10-13

    Various examples are provided for digital sound reconstruction using piezoelectric array elements. In one example, a digital loudspeaker includes a fixed frame and an array of transducers disposed on the fixed frame. Individual transducers of the array of transducers can include a flexible membrane disposed on a piezoelectric actuation element positioned over a corresponding opening that extends through the fixed frame. In another example, a method includes forming a flexible membrane structure on a substrate and backetching the substrate opposite the flexible membrane structure. The flexible membrane structure can be formed by disposing a first electrode layer on a substrate, disposing a piezoelectric layer on the first electrode layer and disposing a second electrode layer on the piezoelectric layer. A flexible membrane layer (e.g., polyimide) can be disposed on the second electrode layer.

  18. Piezoelectric array elements for sound reconstruction with a digital input

    KAUST Repository

    Carreno, Armando Arpys Arevalo; Gonzalez, David Conchouso; Signoret, David Castro; Foulds, Ian G.

    2016-01-01

    Various examples are provided for digital sound reconstruction using piezoelectric array elements. In one example, a digital loudspeaker includes a fixed frame and an array of transducers disposed on the fixed frame. Individual transducers of the array of transducers can include a flexible membrane disposed on a piezoelectric actuation element positioned over a corresponding opening that extends through the fixed frame. In another example, a method includes forming a flexible membrane structure on a substrate and backetching the substrate opposite the flexible membrane structure. The flexible membrane structure can be formed by disposing a first electrode layer on a substrate, disposing a piezoelectric layer on the first electrode layer and disposing a second electrode layer on the piezoelectric layer. A flexible membrane layer (e.g., polyimide) can be disposed on the second electrode layer.

  19. Template-based fabrication of nanowire-nanotube hybrid arrays

    International Nuclear Information System (INIS)

    Ye Zuxin; Liu Haidong; Schultz, Isabel; Wu Wenhao; Naugle, D G; Lyuksyutov, I

    2008-01-01

    The fabrication and structure characterization of ordered nanowire-nanotube hybrid arrays embedded in porous anodic aluminum oxide (AAO) membranes are reported. Arrays of TiO 2 nanotubes were first deposited into the pores of AAO membranes by a sol-gel technique. Co nanowires were then electrochemically deposited into the TiO 2 nanotubes to form the nanowire-nanotube hybrid arrays. Scanning electron microscopy and transmission electron microscopy measurements showed a high nanowire filling factor and a clean interface between the Co nanowire and the TiO 2 nanotube. Application of these hybrids to the fabrication of ordered nanowire arrays with highly controllable geometric parameters is discussed

  20. Large-scale membrane transfer process: its application to single-crystal-silicon continuous membrane deformable mirror

    International Nuclear Information System (INIS)

    Wu, Tong; Sasaki, Takashi; Hane, Kazuhiro; Akiyama, Masayuki

    2013-01-01

    This paper describes a large-scale membrane transfer process developed for the construction of large-scale membrane devices via the transfer of continuous single-crystal-silicon membranes from one substrate to another. This technique is applied for fabricating a large stroke deformable mirror. A bimorph spring array is used to generate a large air gap between the mirror membrane and the electrode. A 1.9 mm × 1.9 mm × 2 µm single-crystal-silicon membrane is successfully transferred to the electrode substrate by Au–Si eutectic bonding and the subsequent all-dry release process. This process provides an effective approach for transferring a free-standing large continuous single-crystal-silicon to a flexible suspension spring array with a large air gap. (paper)

  1. Black holes at neutrino telescopes

    International Nuclear Information System (INIS)

    Kowalski, M.; Ringwald, A.; Tu, H.

    2002-01-01

    In scenarios with extra dimensions and TeV-scale quantum gravity, black holes are expected to be produced in the collision of light particles at center-of-mass energies above the fundamental Planck scale with small impact parameters. Black hole production and evaporation may thus be studied in detail at the large hadron collider (LHC). But even before the LHC starts operating, neutrino telescopes such as AMANDA/IceCube, ANTARES, Baikal, and RICE have an opportunity to search for black hole signatures. Black hole production in the scattering of ultrahigh energy cosmic neutrinos on nucleons in the ice or water may initiate cascades and through-going muons with distinct characteristics above the Standard Model rate. In this Letter, we investigate the sensitivity of neutrino telescopes to black hole production and compare it to the one expected at the Pierre Auger Observatory, an air shower array currently under construction, and at the LHC. We find that, already with the currently available data, AMANDA and RICE should be able to place sensible constraints in black hole production parameter space, which are competitive with the present ones from the air shower facilities Fly's Eye and AGASA. In the optimistic case that a ultrahigh energy cosmic neutrino flux significantly higher than the one expected from cosmic ray interactions with the cosmic microwave background radiation is realized in nature, one even has discovery potential for black holes at neutrino telescopes beyond the reach of LHC. (orig.)

  2. Successful closure of treatment-naïve, flat edge (Type II, full-thickness macular hole using inverted internal limiting membrane flap technique

    Directory of Open Access Journals (Sweden)

    Hussain N

    2016-10-01

    Full Text Available Nazimul Hussain,1 Anjli Hussain2 1Department of Ophthalmology, Al Zahra Hospital, 2Al Zahra Medical Center, Dubai, United Arab Emirates Objective: The objective of this study was to present the outcome of the internal limiting membrane (ILM peeling flap technique for a treatment-naïve, flat edge (Type II, full-thickness macular hole (MH. Methods: A 52-year-old man presented with complaints of decreased vision and seeing black spot. He was diagnosed to have a flat edge, full-thickness MH, which was confirmed by optical coherence tomography (OCT. He underwent 23G vitrectomy with brilliant blue G-assisted inverted ILM peeling with an inverted flap over the hole followed by fluid gas exchange. Results: Postoperative follow-up until 3 months showed successful closure of the MH, which was confirmed by OCT. The best-corrected visual acuity improved from baseline 6/60 to 6/12 at the final follow-up. Conclusion: Using the inverted ILM flap technique, a treatment-naïve, flat edge (Type II, full thickness MH achieved successful anatomical and functional outcomes. Keywords: macular hole, inverted ILM, optical coherence tomography

  3. Vitrectomy with internal limiting membrane peeling versus no peeling for idiopathic full-thickness macular hole.

    Science.gov (United States)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil W; Burr, Jennifer; Cook, Jonathan; Boachie, Charles; Tadayoni, Ramin; la Cour, Morten; Christensen, Ulrik; Kwok, Alvin K H

    2014-03-01

    To determine whether internal limiting membrane (ILM) peeling improves anatomic and functional outcomes of full-thickness macular hole (FTMH) surgery when compared with the no-peeling technique. Systematic review and individual participant data (IPD) meta-analysis undertaken under the auspices of the Cochrane Eyes and Vision Group. Only randomized controlled trials (RCTs) were included. Patients with idiopathic stage 2, 3, and 4 FTMH undergoing vitrectomy with or without ILM peeling. Macular hole surgery, including vitrectomy and gas endotamponade with or without ILM peeling. Primary outcome was best-corrected distance visual acuity (BCdVA) at 6 months postoperatively. Secondary outcomes were BCdVA at 3 and 12 months; best-corrected near visual acuity (BCnVA) at 3, 6, and 12 months; primary (after a single surgery) and final (after >1 surgery) macular hole closure; need for additional surgical interventions; intraoperative and postoperative complications; patient-reported outcomes (PROs) (EuroQol-5D and Vision Function Questionnaire-25 scores at 6 months); and cost-effectiveness. Four RCTs were identified and included in the review. All RCTs were included in the meta-analysis; IPD were obtained from 3 of the 4 RCTs. No evidence of a difference in BCdVA at 6 months was detected (mean difference, -0.04; 95% confidence interval [CI], -0.12 to 0.03; P=0.27); however, there was evidence of a difference in BCdVA at 3 months favoring ILM peeling (mean difference, -0.09; 95% CI, -0.17 to-0.02; P=0.02). There was evidence of an effect favoring ILM peeling with regard to primary (odds ratio [OR], 9.27; 95% CI, 4.98-17.24; Ppeeling was found to be highly cost-effective. Available evidence supports ILM peeling as the treatment of choice for patients with idiopathic stage 2, 3, and 4 FTMH. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  4. Mechanical frequency selectivity of an artificial basilar membrane using a beam array with narrow supports

    International Nuclear Information System (INIS)

    Kim, Sangwon; Jang, Jongmoon; Choi, Hongsoo; Song, Won Joon; Jang, Jeong Hun

    2013-01-01

    The study presented in this paper assessed the frequency selectivity of an artificial basilar membrane (ABM) constructed using a piezoelectric beam array with narrow supports. Three ABM samples were constructed. Each ABM contained 16 beams with various lengths in a one-dimensional array. To experimentally assess the frequency selectivity of the ABM, mechanical vibration induced either by an electrical or an acoustic stimulus was measured with a scanning laser-Doppler vibrometer. The electro-mechanical and acousto-mechanical transfer functions were defined for the same purpose. The tonotopy of each beam array was visualized by post-processing the experimental results. Finite element analyses were conducted to numerically compute the resonance frequencies, identify the associated vibrational modes, and evaluate the harmonic responses of the beams. The influence of the residual stresses existing in the beams was reflected in the geometric models by introducing three different levels of arc-shaped lateral deformations in the beams. The harmonic analyses revealed that each beam of the ABM samples presented independent band-pass characteristics. The experiments and simulations commonly showed a frequency selectivity of the fabricated ABMs in the range of 2–20 kHz. Therefore, the device is suitable for development of a totally implantable artificial cochlea, implementing a mechanical frequency analyzer. This work is part of research to develop a prototype of a totally implantable artificial cochlea. (paper)

  5. Annexin A4 and A6 induce membrane curvature and constriction during cell membrane repair

    DEFF Research Database (Denmark)

    Boye, Theresa Louise; Maeda, Kenji; Pezeshkian, Weria

    2017-01-01

    Efficient cell membrane repair mechanisms are essential for maintaining membrane integrity and thus for cell life. Here we show that the Ca2+- and phospholipid-binding proteins annexin A4 and A6 are involved in plasma membrane repair and needed for rapid closure of micron-size holes. We demonstrate...... that annexin A4 binds to artificial membranes and generates curvature force initiated from free edges, whereas annexin A6 induces constriction force. In cells, plasma membrane injury and Ca2+ influx recruit annexin A4 to the vicinity of membrane wound edges where its homo-trimerization leads to membrane...... that induction of curvature force around wound edges is an early key event in cell membrane repair....

  6. Fabrication and optical properties of TiO sub 2 nanowire arrays made by sol-gel electrophoresis deposition into anodic alumina membranes

    CERN Document Server

    Lin, Y; Yuan, X Y; Xie, T; Zhang, L D

    2003-01-01

    Ordered TiO sub 2 nanowire arrays have been successfully fabricated into the nanochannels of a porous anodic alumina membrane by sol-gel electrophoretic deposition. After annealing at 500 deg. C, the TiO sub 2 nanowire arrays and the individual nanowires were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and x-ray diffraction (XRD). SEM and TEM images show that these nanowires are dense and continuous with a uniform diameter throughout their entire length. XRD and SAED analysis together indicate that these TiO sub 2 nanowires crystallize in the anatase polycrystalline structure. The optical absorption band edge of TiO sub 2 nanowire arrays exhibits a blue shift with respect of that of the bulk TiO sub 2 owing to the quantum size effect.

  7. [Anatomical and functional results of macular hole surgery with internal limiting membrane peeling after 10-year follow-up].

    Science.gov (United States)

    Foveau, P; Conart, J-B; Hubert, I; Selton, J; Berrod, J-P

    2016-09-01

    To evaluate the anatomical and functional results of macular hole surgery with internal limiting membrane (ILM) peeling after 10 years follow-up. Monocentric retrospective study of patients who had undergone macular hole surgery between 2003 and 2005 in the Nancy University Medical Center and still followed in the department in 2014. All patients underwent pars plana vitrectomy and ILM peeling without staining. Clinical examination at ten years including determination of best-corrected visual acuity (BCVA), evaluation of quality of life and spectral domain optical coherence tomography was performed. Four men and six women with mean age of 64±8 years were included. The mean diameter of the MH was 395±133μm. The mean best corrected visual acuity improved significantly from 0.90±0.22 logMAR to 0.14±0.14 logMAR after 10 years with a satisfactory quality of life in 90 % of patients. The integrity of the IS/OS layer was preserved in 9 eyes. Inner retinal dimples located in the temporal quadrant related to ILM peeling initiation were observed in 8 eyes. No significant RNFL or ganglion cell complex changes were found compared to the contralateral eye. Macular hole surgery with ILM peeling in this series resulted in a visual acuity gain of 8 ETDRS lines and persistent improvement in quality of life after a 10-year follow-up. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  8. Fabrication of In Vitro Cancer Microtissue Array on Fibroblast-Layered Nanofibrous Membrane by Inkjet Printing

    Directory of Open Access Journals (Sweden)

    Tae-Min Park

    2017-11-01

    Full Text Available In general, a drug candidate is evaluated using 2D-cultured cancer cells followed by an animal model. Despite successful preclinical testing, however, most drugs that enter human clinical trials fail. The high failure rates are mainly caused by incompatibility between the responses of the current models and humans. Here, we fabricated a cancer microtissue array in a multi-well format that exhibits heterogeneous and batch-to-batch structure by continuous deposition of collagen-suspended Hela cells on a fibroblast-layered nanofibrous membrane via inkjet printing. Expression of both Matrix Metalloproteinase 2 (MMP2 and Matrix Metalloproteinase 9 (MMP9 was higher in cancer microtissues than in fibroblast-free microtissues. The fabricated microtissues were treated with an anticancer drug, and high drug resistance to doxorubicin occurred in cancer microtissues but not in fibroblast-free microtissues. These results introduce an inkjet printing fabrication method for cancer microtissue arrays, which can be used for various applications such as early drug screening and gradual 3D cancer studies.

  9. HEMI-TEMPORAL INTERNAL LIMITING MEMBRANE PEELING IS AS EFFECTIVE AND SAFE AS CONVENTIONAL FULL PEELING FOR MACULAR HOLE SURGERY.

    Science.gov (United States)

    Shiono, Akira; Kogo, Jiro; Sasaki, Hiroki; Yomoda, Ryo; Jujo, Tatsuya; Tokuda, Naoto; Kitaoka, Yasushi; Takagi, Hitoshi

    2018-05-09

    To investigate the efficacy of hemi-temporal internal limiting membrane (ILM) peeling for idiopathic macular hole. The medical records of patients with macular holes who had undergone vitrectomy with ILM peeling were studied. Forty-two eyes with macular hole were divided into 2 groups based on surgical procedure (hemi-temporal ILM peeling [hemi group]: 15 eyes; 360° ILM peeling [360° group]: 27 eyes). The closure rates and distances between the optic disc and the intersection of two retinal vessels most closely located nasally or temporally to the macular hole were compared. The primary closure rates were not significantly different between the two groups (hemi group: 93.3%; 360° group: 92.5%, P = 0.92). The temporal retinal vessels in the hemi group were displaced 120.5 ± 102.0 µm toward the optic disc at 1 week postoperatively, which did not differ significantly from the 360° group (136.1 ± 106.1 µm) (P = 0.107). However, the nasal retinal vessels in the hemi group were displaced by 42.4 ± 42.9 µm at 1 week postoperatively, which was significantly less than the 90.1 ± 77.3 µm displacement seen in the 360° group (P = 0.040). Hemi-temporal ILM peeling may be preferable to 360° ILM peeling because of less displacement of the retina and greater safety.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

  10. A tunable sub-100 nm silicon nanopore array with an AAO membrane mask: reducing unwanted surface etching by introducing a PMMA interlayer

    Science.gov (United States)

    Lim, Namsoo; Pak, Yusin; Kim, Jin Tae; Hwang, Youngkyu; Lee, Ryeri; Kumaresan, Yogeenth; Myoung, Nosoung; Ko, Heung Cho; Jung, Gun Young

    2015-08-01

    Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array.Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer

  11. Microwave-Driven Multifunctional Capability of Membrane Structures

    Science.gov (United States)

    Choi, Sang H.; Chu, Sang-Hyong; Song, Kyo D.; King, Glen C.

    2002-01-01

    A large, ultra lightweight space structure, such as solar sails and Gossamer spacecrafts, requires a distributed power source to alleviate wire networks, unlike the localized on-board power infrastructures typically found in most small spacecrafts. The concept of microwave-driven multifunctional capability for membrane structures is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry and on-board power infrastructures. A rectenna array based on a patch configuration for high voltage output was developed to drive membrane actuators, sensors, probes, or other devices. Networked patch rectenna array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is adopted for networking a rectenna/actuator patch array. The use of patch rectennas adds a significant amount of rigidity to membrane flexibility and they are relatively heavy. A dipole rectenna array (DRA) appears to be ideal for thin-film membrane structures, since DRA is flexible and light. Preliminary design and fabrication of PAD circuitry that consists of a few nodal elements were made for laboratory testing. The networked actuators were tested to correlate the network coupling effect, power allocation and distribution, and response time.

  12. Direction-of-Arrival Estimation for Coprime Array Using Compressive Sensing Based Array Interpolation

    Directory of Open Access Journals (Sweden)

    Aihua Liu

    2017-01-01

    Full Text Available A method of direction-of-arrival (DOA estimation using array interpolation is proposed in this paper to increase the number of resolvable sources and improve the DOA estimation performance for coprime array configuration with holes in its virtual array. The virtual symmetric nonuniform linear array (VSNLA of coprime array signal model is introduced, with the conventional MUSIC with spatial smoothing algorithm (SS-MUSIC applied on the continuous lags in the VSNLA; the degrees of freedom (DoFs for DOA estimation are obviously not fully exploited. To effectively utilize the extent of DoFs offered by the coarray configuration, a compressing sensing based array interpolation algorithm is proposed. The compressing sensing technique is used to obtain the coarse initial DOA estimation, and a modified iterative initial DOA estimation based interpolation algorithm (IMCA-AI is then utilized to obtain the final DOA estimation, which maps the sample covariance matrix of the VSNLA to the covariance matrix of a filled virtual symmetric uniform linear array (VSULA with the same aperture size. The proposed DOA estimation method can efficiently improve the DOA estimation performance. The numerical simulations are provided to demonstrate the effectiveness of the proposed method.

  13. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Lani, Shane W., E-mail: shane.w.lani@gmail.com, E-mail: karim.sabra@me.gatech.edu, E-mail: levent.degertekin@me.gatech.edu; Sabra, Karim G. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); Wasequr Rashid, M.; Hasler, Jennifer [School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States); Levent Degertekin, F. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States)

    2014-02-03

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range.

  14. Sub-electron transport in single-electron-tunneling arrays

    Science.gov (United States)

    Kaplan, Daniel; Sverdlov, Viktor; Korotkov, Alexander; Likharev, Konstantin

    2002-03-01

    We have analyzed quasi-continuous charge transport in two-dimensional tunnel junction arrays with a special distribution of background charges, providing a complete suppression of Coulomb blockade thresholds of tunneling between any pair of islands. Numerical simulations show that at low currents the dc I-V curve is indeed linear, while the shot noise is strongly suppressed and approaches 1/N of the Schottky value (where N is the array length). Thus both conditions of quasi-continuous transport, formulated earlier by Matsuoka and Likharev (Phys. Rev. B, v57, 15613, 1998), are satisfied. At higher fields the electron-hole pair production begins, and shot noise grows sharply. At higher voltages still, the array enters the "plasma" regime (with nearly balanced number of electrons and holes) and the Fano factor drops to 1/N once again. We have studied the resulting shot noise peak in detail, and concluded that its physics is close to that of critical opalescence.

  15. Extraordinary mid-infrared transmission of subwavelength holes in gold films

    KAUST Repository

    Yue, Weisheng

    2014-04-01

    Gold (Au) nanoholes are fabricated with electron-beam lithography and used for the investigation of extraordinary transmission in mid-infrared regime. Transmission properties of the nanoholes are studied as the dependence on hole-size. Transmittance spectra are characterized by Fourier transform infrared spectroscopy (FTIR) and enhanced transmittance through the subwavelength holes is observed. The transmission spectra exhibit well-defined maximum and minimum of which the position are determined by the lattice of the hole array. The hole-size primarily influence the transmission intensity and bandwidth of the resonance peak. With an increase of hole-size, while keep lattice constant fixed, the intensity of the resonance peak and the bandwidth increases, which are due to the localized surface plasmons. Numerical simulation for the transmission through the subwavelength holes is performed and the simulated results agree with the experimental observations. Copyright © 2014 American Scientific Publishers.

  16. Extraordinary mid-infrared transmission of subwavelength holes in gold films

    KAUST Repository

    Yue, Weisheng; Wang, Zhihong; Yang, Yang; Chen, Longqing; Syed, Ahad A.; Wang, Xianbin

    2014-01-01

    Gold (Au) nanoholes are fabricated with electron-beam lithography and used for the investigation of extraordinary transmission in mid-infrared regime. Transmission properties of the nanoholes are studied as the dependence on hole-size. Transmittance spectra are characterized by Fourier transform infrared spectroscopy (FTIR) and enhanced transmittance through the subwavelength holes is observed. The transmission spectra exhibit well-defined maximum and minimum of which the position are determined by the lattice of the hole array. The hole-size primarily influence the transmission intensity and bandwidth of the resonance peak. With an increase of hole-size, while keep lattice constant fixed, the intensity of the resonance peak and the bandwidth increases, which are due to the localized surface plasmons. Numerical simulation for the transmission through the subwavelength holes is performed and the simulated results agree with the experimental observations. Copyright © 2014 American Scientific Publishers.

  17. Role of shape of hole in transmission and negative refractive index of sandwiched metamaterials

    International Nuclear Information System (INIS)

    Zhong Min; Ye Yong-Hong

    2014-01-01

    Transmission and negative refractive index (NRI) of metal—dielectric—metal (MDM) sandwiched metamaterial perforated with four kinds of shapes of holes are numerically studied. Results indicate that positions of all transmission peaks of these kinds of holes are sensitive to the shape of the hole. Under the same conditions, the circular hole can obtain the maximum NRI and the rectangular hole can obtain the maximum frequency bandwidth of NRI. Moreover, the figure of merit (FOM) of the circular hole is the maximum too. As a result, we can obtain a higher NRI and FOM metamaterial by drilling circular hole arrays on MDM metamaterial. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  18. Interaction of poly(amidoamine) dendrimers with supported lipid bilayers and cells: hole formation and the relation to transport.

    Science.gov (United States)

    Hong, Seungpyo; Bielinska, Anna U; Mecke, Almut; Keszler, Balazs; Beals, James L; Shi, Xiangyang; Balogh, Lajos; Orr, Bradford G; Baker, James R; Banaszak Holl, Mark M

    2004-01-01

    We have investigated poly(amidoamine) (PAMAM) dendrimer interactions with supported 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayers and KB and Rat2 cell membranes using atomic force microscopy (AFM), enzyme assays, flow cell cytometry, and fluorescence microscopy. Amine-terminated generation 7 (G7) PAMAM dendrimers (10-100 nM) were observed to form holes of 15-40 nm in diameter in aqueous, supported lipid bilayers. G5 amine-terminated dendrimers did not initiate hole formation but expanded holes at existing defects. Acetamide-terminated G5 PAMAM dendrimers did not cause hole formation in this concentration range. The interactions between PAMAM dendrimers and cell membranes were studied in vitro using KB and Rat 2 cell lines. Neither G5 amine- nor acetamide-terminated PAMAM dendrimers were cytotoxic up to a 500 nM concentration. However, the dose dependent release of the cytoplasmic proteins lactate dehydrogenase (LDH) and luciferase (Luc) indicated that the presence of the amine-terminated G5 PAMAM dendrimer decreased the integrity of the cell membrane. In contrast, the presence of acetamide-terminated G5 PAMAM dendrimer had little effect on membrane integrity up to a 500 nM concentration. The induction of permeability caused by the amine-terminated dendrimers was not permanent, and leaking of cytosolic enzymes returned to normal levels upon removal of the dendrimers. The mechanism of how PAMAM dendrimers altered cells was investigated using fluorescence microscopy, LDH and Luc assays, and flow cytometry. This study revealed that (1) a hole formation mechanism is consistent with the observations of dendrimer internalization, (2) cytosolic proteins can diffuse out of the cell via these holes, and (3) dye molecules can be detected diffusing into the cell or out of the cell through the same membrane holes. Diffusion of dendrimers through holes is sufficient to explain the uptake of G5 amine-terminated PAMAM dendrimers into cells and is consistent

  19. Cosmological horizons as new examples of the membrane paradigm

    International Nuclear Information System (INIS)

    Wang, Tower

    2015-01-01

    In this paper we aim to provide new examples of the application and the generality of the membrane paradigm. The membrane paradigm is a formalism for studying the event horizon of black holes. After analyzing it with some technical details and realizing it in the Reissner–Nordström black hole, we apply the paradigm to cosmological horizons, first to the pure de Sitter horizon, and then to the trapping horizon of the Friedmann–Lemaître–Robertson–Walker Universe. In the latter case, the cosmological stretched horizon is oblique, thus the running of the renormalization parameter is nonzero in the timelike direction and gives a correction to the membrane pressure. In this paradigm, the cosmological equations come from continuity equations of the membrane fluid and the bulk fluid respectively. (paper)

  20. Indocyanine green-assisted internal limiting membrane peeling in macular hole surgery: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Yan Wu

    Full Text Available BACKGROUND: The opinion of application of indocyanine green (ICG in the macular hole surgery was contradictory. Here we conducted a meta-analysis to evaluate the effect of in internal limiting membrane (ILM peeling for macular hole surgery. METHODS AND FINDINGS: We searched electronic databases for comparative studies published before July 2012 of ILM peeling with and without ICG. Twenty-two studies including 1585 eyes were included. Visual acuity (VA improvement, including the postoperative rate of ≥20/40 VA gained (OR, 0.65; 95% CI, 0.43 to 0.97; P = 0.033 and increased LogMAR (WMD, -0.09; 95% CI, -0.16 to -0.02; P = 0.011, was less in the ICG group. The risk of visual field defects was greater in the ICG group than in the non-ICG group. There was no significant difference in the rate of anatomical outcomes between ILM peeling procedures performed with and without ICG. RPE changes and other postoperative complications were not significantly different between the ICG and non-ICG groups. An additional analysis showed that the VA improvement of the ICG group was less than the non-ICG group only within the first year of follow up. A subgroup analysis showed that the rate of VA improvement was lower in the ICG group than in other adjuncts group. A higher rate of secondary closure and less VA improvement were observed in a high proportion (>0.1% of the ICG group. A sensitivity analysis after the randomized-controlled trials were excluded from the meta-analysis demonstrated no differences compared with the overall results. CONCLUSIONS: This meta-analysis demonstrated that there is no evidence of clinical superiority in outcomes for ICG-assisted ILM peeling procedure over the non-ICG one. The toxicity of ICG should be considered when choosing the various staining methods.

  1. Design of a new electrode array for cochlear implants

    International Nuclear Information System (INIS)

    Kha, H.; Chen, B.

    2010-01-01

    Full text: This study aims to design a new electrode array which can be precisely located beneath the basilar membrane within the cochlear scala tympani. This placement of the electrode array is beneficial for increasing the effectiveness of the electrical stimulation of the audi tory nerves and maximising the growth factors delivered into the cochlea for regenerating the progressively lost auditory neurons, thereby significantly improving performance of the cochlear implant systems. Methods The design process involved two steps. First, the biocom patible nitinol-based shape memory alloy, of which mechanical deformation can be controlled using electrical cUTents/fields act vated by body temperature, was selected. Second, five different designs of the electrode array with embedded nitinol actuators were studied (Table I). The finite element method was employed to predict final positions of these electrode arrays. Results The electrode array with three 6 mm actuators at 2-8, 8-J4 and 14-20 mm from the tip (Fig. I) was found to be located most closely to the basilar membrane, compared with those in the other four cases. Conclusions A new nitinol cochlear implant electrode array with three embedded nitinol actuators has been designed. This electrode array is expected to be located beneath the basilar membrane for maximising the delivery of growth factors. Future research will involve the manufacturing of a prototype of this electrode array for use in insertion experiments and neurotrophin release tests.

  2. Ordered Au Nanodisk and Nanohole Arrays: Fabrication and Applications

    KAUST Repository

    Zheng, Yue Bing; Juluri, Bala Krishna; Kiraly, Brian; Huang, Tony Jun

    2010-01-01

    We have utilized nanosphere lithography (NSL) to fabricate ordered Au nanodisk and nanohole arrays on substrates and have studied the localized surface plasmon resonance (LSPR) of the arrays. Through these investigations, we demonstrate that the angle- dependent behavior of the LSPR in the Au nanodisk arrays enables real-time observation of exciton-plasmon couplings. In addition, we show that the NSL-fabricated Au nanohole arrays can be applied as templates for patterning micro-/nanoparticles under capillary force. The unique structural and plasmonic characteristics of the Au nanodisk and nano- hole arrays, as well as the low-cost and high-throughput NSL-based nanofabrication technique, render these arrays excellent platforms for numerous engineering applications. © 2010 by ASME.

  3. Preparation of Microcrystals of Piroxicam Monohydrate by Antisolvent Precipitation via Microfabricated Metallic Membranes with Ordered Pore Arrays.

    Science.gov (United States)

    Othman, Rahimah; Vladisavljević, Goran T; Simone, Elena; Nagy, Zoltan K; Holdich, Richard G

    2017-12-06

    Microcrystals of piroxicam (PRX) monohydrate with a narrow size distribution were prepared from acetone/PRX solutions by antisolvent crystallization via metallic membranes with ordered pore arrays. Crystallization was achieved by controlled addition of the feed solution through the membrane pores into a well-stirred antisolvent. A complete transformation of an anhydrous form I into a monohydrate form of PRX was confirmed by Raman spectroscopy and differential scanning calorimetry. The size of the crystals was 7-34 μm and was controlled by the PRX concentration in the feed solution (15-25 g L -1 ), antisolvent/solvent volume ratio (5-30), and type of antisolvent (Milli-Q water or 0.1-0.5 wt % aqueous solutions of hydroxypropyl methyl cellulose (HPMC), poly(vinyl alcohol) or Pluronic P-123). The smallest crystals were obtained by injecting 25 g L -1 PRX solution through a stainless-steel membrane with a pore size of 10 μm into a 0.06 wt % HPMC solution stirred at 1500 rpm using an antisolvent/solvent ratio of 20. HPMC provided better steric stabilization of microcrystals against agglomeration than poly(vinyl alcohol) and Pluronic P-123, due to hydrogen bonding interactions with PRX and water. A continuous production of large PRX monohydrate microcrystals with a volume-weighted mean diameter above 75 μm was achieved in a continuous stirred membrane crystallizer. Rapid pouring of Milli-Q water into the feed solution resulted in a mixture of highly polydispersed prism-shaped and needle-shaped crystals.

  4. En face spectral domain optical coherence tomography analysis of lamellar macular holes.

    Science.gov (United States)

    Clamp, Michael F; Wilkes, Geoff; Leis, Laura S; McDonald, H Richard; Johnson, Robert N; Jumper, J Michael; Fu, Arthur D; Cunningham, Emmett T; Stewart, Paul J; Haug, Sara J; Lujan, Brandon J

    2014-07-01

    To analyze the anatomical characteristics of lamellar macular holes using cross-sectional and en face spectral domain optical coherence tomography. Forty-two lamellar macular holes were retrospectively identified for analysis. The location, cross-sectional length, and area of lamellar holes were measured using B-scans and en face imaging. The presence of photoreceptor inner segment/outer segment disruption and the presence or absence of epiretinal membrane formation were recorded. Forty-two lamellar macular holes were identified. Intraretinal splitting occurred within the outer plexiform layer in 97.6% of eyes. The area of intraretinal splitting in lamellar holes did not correlate with visual acuity. Eyes with inner segment/outer segment disruption had significantly worse mean logMAR visual acuity (0.363 ± 0.169; Snellen = 20/46) than in eyes without inner segment/outer segment disruption (0.203 ± 0.124; Snellen = 20/32) (analysis of variance, P = 0.004). Epiretinal membrane was present in 34 of 42 eyes (81.0%). En face imaging allowed for consistent detection and quantification of intraretinal splitting within the outer plexiform layer in patients with lamellar macular holes, supporting the notion that an area of anatomical weakness exists within Henle's fiber layer, presumably at the synaptic connection of these fibers within the outer plexiform layer. However, the en face area of intraretinal splitting did not correlate with visual acuity, disruption of the inner segment/outer segment junction was associated with significantly worse visual acuity in patients with lamellar macular holes.

  5. Optimal management of idiopathic macular holes.

    Science.gov (United States)

    Madi, Haifa A; Masri, Ibrahim; Steel, David H

    2016-01-01

    This review evaluates the current surgical options for the management of idiopathic macular holes (IMHs), including vitrectomy, ocriplasmin (OCP), and expansile gas use, and discusses key background information to inform the choice of treatment. An evidence-based approach to selecting the best treatment option for the individual patient based on IMH characteristics and patient-specific factors is suggested. For holes without vitreomacular attachment (VMA), vitrectomy is the only option with three key surgical variables: whether to peel the inner limiting membrane (ILM), the type of tamponade agent to be used, and the requirement for postoperative face-down posturing. There is a general consensus that ILM peeling improves primary anatomical hole closure rate; however, in small holes (holes, but large (>400 µm) and chronic holes (>1-year history) are usually treated with long-acting gas and posturing. Several studies on posturing and gas choice were carried out in combination with ILM peeling, which may also influence the gas and posturing requirement. Combined phacovitrectomy appears to offer more rapid visual recovery without affecting the long-term outcomes of vitrectomy for IMH. OCP is licensed for use in patients with small- or medium-sized holes and VMA. A greater success rate in using OCP has been reported in smaller holes, but further predictive factors for its success are needed to refine its use. It is important to counsel patients realistically regarding the rates of success with intravitreal OCP and its potential complications. Expansile gas can be considered as a further option in small holes with VMA; however, larger studies are required to provide guidance on its use.

  6. Silicon nitride nanosieve membrane

    NARCIS (Netherlands)

    Tong, D.H.; Jansen, Henricus V.; Gadgil, V.J.; Bostan, C.G.; Berenschot, Johan W.; van Rijn, C.J.M.; Elwenspoek, Michael Curt

    2004-01-01

    An array of very uniform cylindrical nanopores with a pore diameter as small as 25 nm has been fabricated in an ultrathin micromachined silicon nitride membrane using focused ion beam (FIB) etching. The pore size of this nanosieve membrane was further reduced to below 10 nm by coating it with

  7. In situ x-ray diffraction study on AgI nanowire arrays

    International Nuclear Information System (INIS)

    Wang Yinhai; Ye Changhui; Wang Guozhong; Zhang Lide; Liu Yanmei; Zhao Zhongyan

    2003-01-01

    The AgI nanowire arrays were prepared in the ordered porous alumina membrane by an electrochemical method. Transmission electron microscopy observation shows that the AgI nanowires are located in the channels of the alumina membrane. In situ x-ray diffractions show that the nanowire arrays possess hexagonal close-packed structure (β-AgI) at 293 K, orienting along the (002) plane, whereas at 473 K, the nanowire arrays possess a body-centered cubic structure (α-AgI), orienting along the (110) plane. The AgI nanowire arrays exhibit a negative thermal expansion property from 293 to 433 K, and a higher transition temperature from the β to α phase. We ascribe the negative thermal expansion behavior to the phase transition from the β to α phase, and the elevated transition temperature to the radial restriction by the channels of alumina membrane

  8. Large-scale fabrication of vertically aligned ZnO nanowire arrays

    Science.gov (United States)

    Wang, Zhong L; Das, Suman; Xu, Sheng; Yuan, Dajun; Guo, Rui; Wei, Yaguang; Wu, Wenzhuo

    2013-02-05

    In a method for growing a nanowire array, a photoresist layer is placed onto a nanowire growth layer configured for growing nanowires therefrom. The photoresist layer is exposed to a coherent light interference pattern that includes periodically alternately spaced dark bands and light bands along a first orientation. The photoresist layer exposed to the coherent light interference pattern along a second orientation, transverse to the first orientation. The photoresist layer developed so as to remove photoresist from areas corresponding to areas of intersection of the dark bands of the interference pattern along the first orientation and the dark bands of the interference pattern along the second orientation, thereby leaving an ordered array of holes passing through the photoresist layer. The photoresist layer and the nanowire growth layer are placed into a nanowire growth environment, thereby growing nanowires from the nanowire growth layer through the array of holes.

  9. Quasi-optical antenna-mixer-array design for terahertz frequencies

    Science.gov (United States)

    Guo, Yong; Potter, Kent A.; Rutledge, David B.

    1992-01-01

    A new quasi-optical antenna-mixer-array design for terahertz frequencies is presented. In the design, antenna and mixer are combined into an entity, based on the technology in which millimeter-wave horn antenna arrays have been fabricated in silicon wafers. It consists of a set of forward- and backward-looking horns made with a set of silicon wafers. The front side is used to receive incoming signal, and the back side is used to feed local oscillator signal. Intermediate frequency is led out from the side of the array. Signal received by the horn array is picked up by antenna probes suspended on thin silicon-oxynitride membranes inside the horns. Mixer diodes will be located on the membranes inside the horns. Modeling of such an antenna-mixer-array design is done on a scaled model at microwave frequencies. The impedance matching, RF and LO isolation, and patterns of the array have been tested and analyzed.

  10. Ceramic oxygen transport membrane array reactor and reforming method

    Science.gov (United States)

    Kelly, Sean M.; Christie, Gervase Maxwell; Robinson, Charles; Wilson, Jamie R; Gonzalez, Javier E.; Doraswami, Uttam R.

    2017-10-03

    The invention relates to a commercially viable modular ceramic oxygen transport membrane system for utilizing heat generated in reactively-driven oxygen transport membrane tubes to generate steam, heat process fluid and/or provide energy to carry out endothermic chemical reactions. The system provides for improved thermal coupling of oxygen transport membrane tubes to steam generation tubes or process heater tubes or reactor tubes for efficient and effective radiant heat transfer.

  11. Ceramic oxygen transport membrane array reactor and reforming method

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Sean M.; Christie, Gervase Maxwell; Robinson, Charles; Wilson, Jamie R.; Gonzalez, Javier E.; Doraswami, Uttam R.

    2016-11-08

    The invention relates to a commercially viable modular ceramic oxygen transport membrane reforming reactor configured using repeating assemblies of oxygen transport membrane tubes and catalytic reforming reactors.

  12. Effective theory of black holes in the 1/D expansion

    International Nuclear Information System (INIS)

    Emparan, Roberto; Shiromizu, Tetsuya; Suzuki, Ryotaku; Tanabe, Kentaro; Tanaka, Takahiro

    2015-01-01

    The gravitational field of a black hole is strongly localized near its horizon when the number of dimensions D is very large. In this limit, we can effectively replace the black hole with a surface in a background geometry (e.g. Minkowski or Anti-deSitter space). The Einstein equations determine the effective equations that this ‘black hole surface’ (or membrane) must satisfy. We obtain them up to next-to-leading order in 1/D for static black holes of the Einstein-(A)dS theory. To leading order, and also to next order in Minkowski backgrounds, the equations of the effective theory are the same as soap-film equations, possibly up to a redshift factor. In particular, the Schwarzschild black hole is recovered as a spherical soap bubble. Less trivially, we find solutions for ‘black droplets’, i.e. black holes localized at the boundary of AdS, and for non-uniform black strings.

  13. Magnetization Reversal Mechanism for CoFeB Ferromagnetic Nanotube Arrays

    International Nuclear Information System (INIS)

    Hai-Rui, Liu; Qing-Feng, Lu; Shamaila, S.; Jun-Yang, Chen; Sharif, R.; Xiu-Feng, Han

    2009-01-01

    CoFeB nanotube arrays are fabricated in anodic aluminum oxide (AAO) membranes and track etched polycarbonate (PCTE) membranes by using an electrochemical method, and their magnetic properties are investigated by vibrating sample magnetometry. The coercivity H c and remanent squareness S Q of these CoFeB nanotube arrays are derived from hysteresis loops as a function of angle between the field and tube axis. The H c (θ) curves for CoFeB nanotube arrays in AAO and PCTE membranes show M-type variation, while they change shape from M to mountain-type as the tube length increases. However, the overall easy axis perpendicular to tube axis does not change with tube length. The different angular dependences are attributed to different magnetization reversal mechanisms. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  14. Rotating black holes which saturate a Bogomol close-quote nyi bound

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Sen, A.

    1996-01-01

    We construct and study the electrically charged, rotating black hole solution in heterotic string theory compactified on a (10-D)-dimensional torus. This black hole is characterized by its mass, angular momentum, and a (36-2D)-dimensional electric charge vector. One of the features of this solution is that for D>5 its extremal limit saturates the Bogomol close-quote nyi bound. This is in contrast with the D=4 case where the rotating black hole solution develops a naked singularity before the Bogomol close-quote nyi bound is reached. The extremal black holes can be superposed, and by taking a periodic array in D>5, one obtains effectively four-dimensional solutions without naked singularities. copyright 1996 The American Physical Society

  15. A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

    Science.gov (United States)

    Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang

    2016-12-01

    In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn2O3, Co3O4 and Cr2O3) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

  16. Fabricating PFPE Membranes for Capillary Electrophoresis

    Science.gov (United States)

    Lee, Michael C.; Willis, Peter A.; Greer, Frank; Rolland, Jason

    2009-01-01

    A process has been developed for fabricating perfluoropolyether (PFPE) membranes that contain microscopic holes of precise sizes at precise locations. The membranes are to be incorporated into laboratory-on-a-chip microfluidic devices to be used in performing capillary electrophoresis. The present process is a modified version of part of the process, described in the immediately preceding article, that includes a step in which a liquid PFPE layer is cured into solid (membrane) form by use of ultraviolet light. In the present process, one exploits the fact that by masking some locations to prevent exposure to ultraviolet light, one can prevent curing of the PFPE in those locations. The uncured PFPE can be washed away from those locations in the subsequent release and cleaning steps. Thus, holes are formed in the membrane in those locations. The most straightforward way to implement the modification is to use, during the ultraviolet-curing step, an ultraviolet photomask similar to the photomasks used in fabricating microelectronic devices. In lieu of such a photomask, one could use a mask made of any patternable ultraviolet-absorbing material (for example, an ink or a photoresist).

  17. Visual outcomes of macular hole surgery

    International Nuclear Information System (INIS)

    Khaqan, H.A.; Muhammad, F.J.

    2016-01-01

    To determine the mean visual improvement after internal limiting membrane (ILM) peeling assisted with brilliant blue staining of ILM in macular hole, and stratify the mean visual improvement in different stages of macular hole. Study Design: Quasi-experimental study. Place and Duration of Study: Eye outpatient department (OPD), Lahore General Hospital, Lahore from October 2013 to December 2014. Methodology: Patients with macular hole underwent measurement of best corrected visual acuity (BCVA) and fundus examination with indirect slit lamp biomicroscopy before surgery. The diagnosis of all patients was confirmed on optical coherence tomography. All patients had 23G trans-conjunctival three ports pars plana vitrectomy, ILM peeling, and endotamponade of SF6. The mean visual improvement of different stages of macular hole was noted. Paired t-test was applied. Results: There were 30 patients, 15 males and 15 females (50%). The mean age was 62 ± 10.95 years. They presented with low mean preoperative visual acuity (VA) of 0.96 ± 0.11 logMar. The mean postoperative VA was 0.63 ± 0.24 logMar. The mean visual increase was 0.33 0.22 logMar (p < 0.001). In patients with stage 2 macular hole, mean visual increase was 0.35 ± 0.20 logMar (p < 0.001). In patients with stage 3 macular hole, mean visual increase was 0.44 ± 0.21 logMar (p < 0.001), and in patients with stage 4 macular hole it was 0.13 ± 0.1 logMar (p = 0.004). Conclusion: ILM peeling assisted with brilliant blue is a promising surgery for those patients who have decreased vision due to macular hole, in 2 - 4 stages of macular hole. (author)

  18. Black Holes Lead Galaxy Growth, New Research Shows

    Science.gov (United States)

    2009-01-01

    Astronomers may have solved a cosmic chicken-and-egg problem -- the question of which formed first in the early Universe -- galaxies or the supermassive black holes seen at their cores. "It looks like the black holes came first. The evidence is piling up," said Chris Carilli, of the National Radio Astronomy Observatory (NRAO). Carilli outlined the conclusions from recent research done by an international team studying conditions in the first billion years of the Universe's history in a lecture presented to the American Astronomical Society's meeting in Long Beach, California. Gas in Distant Galaxy VLA image (right) of gas in young galaxy seen as it was when the Universe was only 870 million years old. CREDIT: NRAO/AUI/NSF, SDSS Full-size JPEG, 323 KB PDF file, 180 KB Galaxy image, no annotation, JPEG 21 KB Earlier studies of galaxies and their central black holes in the nearby Universe revealed an intriguing linkage between the masses of the black holes and of the central "bulges" of stars and gas in the galaxies. The ratio of the black hole and the bulge mass is nearly the same for a wide range of galactic sizes and ages. For central black holes from a few million to many billions of times the mass of our Sun, the black hole's mass is about one one-thousandth of the mass of the surrounding galactic bulge. "This constant ratio indicates that the black hole and the bulge affect each others' growth in some sort of interactive relationship," said Dominik Riechers, of Caltech. "The big question has been whether one grows before the other or if they grow together, maintaining their mass ratio throughout the entire process." In the past few years, scientists have used the National Science Foundation's Very Large Array radio telescope and the Plateau de Bure Interferometer in France to peer far back in the 13.7 billion-year history of the Universe, to the dawn of the first galaxies. "We finally have been able to measure black-hole and bulge masses in several galaxies seen

  19. Nano-pyramid arrays for nano-particle trapping

    NARCIS (Netherlands)

    Sun, Xingwu; Veltkamp, Henk-Willem; Berenschot, Johan W.; Gardeniers, Johannes G.E.; Tas, Niels Roelof

    2016-01-01

    Abstract In this paper we present the drastic miniaturization of nano-wire pyramids fabricated by corner lithography. A particle trapping device was fabricated in a well-defined and symmetrical array. The entrance and exit hole-size can be tuned by adjusting fabrication parameters. We describe here

  20. Vertically Free-Standing Ordered Pb(Zr0.52Ti0.48)O3 Nanocup Arrays by Template-Assisted Ion Beam Etching

    Science.gov (United States)

    Zhang, Xiaoyan; Tang, Dan; Huang, Kangrong; Hu, Die; Zhang, Fengyuan; Gao, Xingsen; Lu, Xubing; Zhou, Guofu; Zhang, Zhang; Liu, Junming

    2016-04-01

    In this report, vertically free-standing lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) nanocup arrays with good ordering and high density (1.3 × 1010 cm-2) were demonstrated. By a template-assisted ion beam etching (IBE) strategy, the PZT formed in the pore-through anodic aluminum oxide (AAO) membrane on the Pt/Si substrate was with a cup-like nanostructure. The mean diameter and height of the PZT nanocups (NCs) was about 80 and 100 nm, respectively, and the wall thickness of NCs was about 20 nm with a hole depth of about 80 nm. Uppermost, the nanocup structure with low aspect ratio realized vertically free-standing arrays when losing the mechanical support from templates, avoiding the collapse or bundling when compared to the typical nanotube arrays. X-ray diffraction (XRD) and Raman spectrum revealed that the as-prepared PZT NCs were in a perovskite phase. By the vertical piezoresponse force microscopy (VPFM) measurements, the vertically free-standing ordered ferroelectric PZT NCs showed well-defined ring-like piezoresponse phase and hysteresis loops, which indicated that the high-density PZT nanocup arrays could have potential applications in ultra-high non-volatile ferroelectric memories (NV-FRAM) or other nanoelectronic devices.

  1. LOW-MASS AGNs AND THEIR RELATION TO THE FUNDAMENTAL PLANE OF BLACK HOLE ACCRETION

    Energy Technology Data Exchange (ETDEWEB)

    Gültekin, Kayhan; King, Ashley L.; Miller, Jon M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Cackett, Edward M. [Department of Physics and Astronomy, Wayne State University, 666 West Hancock Street, Detroit, MI 48201 (United States); Pinkney, Jason, E-mail: kayhan@umich.edu [Department of Physics and Astronomy, Ohio Northern University, 525 S. Main St., Ada, OH 45810 (United States)

    2014-06-20

    We put active galactic nuclei (AGNs) with low-mass black holes on the fundamental plane of black hole accretion—the plane that relates X-ray emission, radio emission, and mass of an accreting black hole—to test whether or not the relation is universal for both stellar-mass and supermassive black holes. We use new Chandra X-ray and Very Large Array radio observations of a sample of black holes with masses less than 10{sup 6.3} M {sub ☉}, which have the best leverage for determining whether supermassive black holes and stellar-mass black holes belong on the same plane. Our results suggest that the two different classes of black holes both belong on the same relation. These results allow us to conclude that the fundamental plane is suitable for use in estimating supermassive black hole masses smaller than ∼10{sup 7} M {sub ☉}, in testing for intermediate-mass black holes, and in estimating masses at high accretion rates.

  2. Four-port gas separation membrane module assembly

    Science.gov (United States)

    Wynn, Nicholas P.; Fulton, Donald A.; Lokhandwala, Kaaeid A.; Kaschemekat, Jurgen

    2010-07-20

    A gas-separation membrane assembly, and a gas-separation process using the assembly. The assembly incorporates multiple gas-separation membranes in an array within a single vessel or housing, and is equipped with two permeate ports, enabling permeate gas to be withdrawn from both ends of the membrane module permeate pipes.

  3. Solar fuel production in a novel polymeric electrolyte membrane photoelectrochemical (PEM-PEC) cell with a web of titania nanotube arrays as photoanode and gaseous reactants

    NARCIS (Netherlands)

    Stoll, T.; Zafeiropoulos, G.; Tsampas, M. N.

    2016-01-01

    A novel photoelectrochemical (PEC) cell design is proposed and investigated for H-2 production with gaseous reactants. The core of the cell is a membrane electrode assembly (MEA) that consists of a TiO2 nanotube arrays photoanode, a Pt/C cathode, a Pt/C reference electrode and a proton conducting

  4. A meta-analysis of vitrectomy with or without internal limiting membrane peeling for macular hole retinal detachment in the highly myopic eyes.

    Science.gov (United States)

    Gao, Xinxiao; Guo, Jia; Meng, Xin; Wang, Jun; Peng, Xiaoyan; Ikuno, Yasushi

    2016-06-13

    To evaluate the anatomical and visual outcomes by par plana vitrectomy with or without internal limiting membrane (ILM) peeling in highly myopic eyes with macular hole retinal detachment (MHRD). MEDLINE (Ovid, PubMed) and EMBASE were used for data collection up to September 30, 2015. The parameters of anatomical success, macular hole closure and improved best corrected visual acuity (BCVA) at or beyond 6 months after operation were assessed as the primary outcome measurement. The meta-analysis was performed with the fixed-effects model. Seven comparative analyses involving a total of 373 patients were included in the present meta-analysis. Statistically the pooled data showed significant relative risk (RR) in terms of primary reattachment between ILM peeling and non-peeling groups (RR, 1.19; 95 % CI, 1.04 to 1.36; P = 0.012). An effect favoring ILM peeling with regard to macular hole closure was also detected (RR, 1.71; 95 % CI, 1.20 to 2.43; P = 0.003). However, no statistically significant difference was found in the improved BCVA (logarithm of the minimum angle of resolution) at 6 months or more (95 % CI, -0.31 to 0.44; P = 0.738). There is no proved benefit of postoperative visual improvement. However, the available evidences from this study suggested a superiority of ILM peeling over no peeling for myopic patients with MHRD.

  5. On explicit thermodynamic functions and extremal limits of Myers-Perry black holes

    International Nuclear Information System (INIS)

    Aaman, Jan E.; Pidokrajt, Narit

    2013-01-01

    We study thermodynamic geometries of Myers-Perry (MP) black holes with arbitrary number of angular momenta. This geometric method allows us to visualize thermodynamic state spaces of the MP black holes as wedges embedded in a Minkowski-like parameter space. The opening angles of these wedges are uniquely determined by the number of spacetime dimensions d, and the number of angular momenta associated with the MP black holes, n. The geometric structure captures extremal limits of the MP black holes, and hence serves as a method for identifying the black hole's extremal limit. We propose that classification of the MP black hole solutions should based on these uncovered structures. In order for the ultraspinning regime to exist, at least one of the angular momenta has to be set to zero. Finally, we conjecture that the membrane phase of ultraspinning MP black holes is reached at the minimum temperature in the case where 2n< d-3 based on the thermodynamic curvature obtained. (orig.)

  6. Solar array experiments on the Sphinx satellite

    Science.gov (United States)

    Stevens, N. J.

    1973-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations; the edge illuminated-multijunction cells, the Teflon encased cells and the violet cells.

  7. Phononic thermal resistance due to a finite periodic array of nano-scatterers

    Energy Technology Data Exchange (ETDEWEB)

    Trang Nghiêm, T. T.; Chapuis, Pierre-Olivier [Univ. Lyon, CNRS, INSA-Lyon, Université Claude Bernard Lyon 1, CETHIL UMR5008, F-69621 Villeurbanne (France)

    2016-07-28

    The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their transmission through a single array for both normal and oblique incidences, using a linear dispersionless time-dependent acoustic frame in a two-dimensional system. Roughness effects can be directly considered within the computations without relying on approximate analytical formulae. Analysis by spatio-temporal Fourier transform allows us to observe the diffraction effects and the conversion of polarization. Frequency-dependent energy transmission coefficients are computed for symmetric and asymmetric objects that are both subject to reciprocity. We demonstrate that the phononic array acts as an efficient thermal barrier by applying the theory of thermal boundary (Kapitza) resistances to arrays of smooth scattering holes in silicon for an exemplifying periodicity of 10 nm in the 5–100 K temperature range. It is observed that the associated thermal conductance has the same temperature dependence as that without phononic filtering.

  8. Extraordinary light transmission through opaque thin metal film with subwavelength holes blocked by metal disks.

    Science.gov (United States)

    Li, Wen-Di; Hu, Jonathan; Chou, Stephen Y

    2011-10-10

    We observed that when subwavelength-sized holes in an optically opaque metal film are completely covered by opaque metal disks larger than the holes, the light transmission through the holes is not reduced, but rather enhanced. Particularly we report (i) the observation of light transmission through the holes blocked by the metal disks up to 70% larger than the unblocked holes; (ii) the observation of tuning the light transmission by varying the coupling strength between the blocking disks and the hole array, or by changing the size of the disks and holes; (iii) the observation and simulation that the metal disk blocker can improve light coupling from free space to a subwavelength hole; and (iv) the simulation that shows the light transmission through subwavelength holes can be enhanced, even though the gap between the disk and the metal film is partially connected with a metal. We believe these finding should have broad and significant impacts and applications to optical systems in many fields.

  9. Creation of defined single cell resolution neuronal circuits on microelectrode arrays

    Science.gov (United States)

    Pirlo, Russell Kirk

    2009-12-01

    The way cell-cell organization of neuronal networks influences activity and facilitates function is not well understood. Microelectrode arrays (MEAs) and advancing cell patterning technologies have enabled access to and control of in vitro neuronal networks spawning much new research in neuroscience and neuroengineering. We propose that small, simple networks of neurons with defined circuitry may serve as valuable research models where every connection can be analyzed, controlled and manipulated. Towards the goal of creating such neuronal networks we have applied microfabricated elastomeric membranes, surface modification and our unique laser cell patterning system to create defined neuronal circuits with single-cell precision on MEAs. Definition of synaptic connectivity was imposed by the 3D physical constraints of polydimethylsiloxane elastomeric membranes. The membranes had 20mum clear-through holes and 2-3mum deep channels which when applied to the surface of the MEA formed microwells to confine neurons to electrodes connected via shallow tunnels to direct neurite outgrowth. Tapering and turning of channels was used to influence neurite polarity. Biocompatibility of the membranes was increased by vacuum baking, oligomer extraction, and autoclaving. Membranes were bound to the MEA by oxygen plasma treatment and heated pressure. The MEA/membrane surface was treated with oxygen plasma, poly-D-lysine and laminin to improve neuron attachment, survival and neurite outgrowth. Prior to cell patterning the outer edge of culture area was seeded with 5x10 5 cells per cm and incubated for 2 days. Single embryonic day 7 chick forebrain neurons were then patterned into the microwells and onto the electrodes using our laser cell patterning system. Patterned neurons successfully attached to and were confined to the electrodes. Neurites extended through the interconnecting channels and connected with adjacent neurons. These results demonstrate that neuronal circuits can be

  10. Fabrication of close-packed TES microcalorimeter arrays using superconducting molybdenum/gold transition-edge sensors

    Science.gov (United States)

    Finkbeiner, F. M.; Brekosky, R. P.; Chervenak, J. A.; Figueroa-Feliciano, E.; Li, M. J.; Lindeman, M. A.; Stahle, C. K.; Stahle, C. M.; Tralshawala, N.

    2002-02-01

    We present an overview of our efforts in fabricating Transition-Edge Sensor (TES) microcalorimeter arrays for use in astronomical x-ray spectroscopy. Two distinct types of array schemes are currently pursued: 5×5 single pixel TES array where each pixel is a TES microcalorimeter, and Position-Sensing TES (PoST) array. In the latter, a row of 7 or 15 thermally-linked absorber pixels is read out by two TES at its ends. Both schemes employ superconducting Mo/Au bilayers as the TES. The TES are placed on silicon nitride membranes for thermal isolation from the structural frame. The silicon nitride membranes are prepared by a Deep Reactive Ion Etch (DRIE) process into a silicon wafer. In order to achieve the concept of closely packed arrays without decreasing its structural and functional integrity, we have already developed the technology to fabricate arrays of cantilevered pixel-sized absorbers and slit membranes in silicon nitride films. Furthermore, we have started to investigate ultra-low resistance through-wafer micro-vias to bring the electrical contact out to the back of a wafer. .

  11. INTRASURGICAL MICROSCOPE-INTEGRATED SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY-ASSISTED MEMBRANE PEELING.

    Science.gov (United States)

    Falkner-Radler, Christiane I; Glittenberg, Carl; Gabriel, Max; Binder, Susanne

    2015-10-01

    To evaluate microscope-integrated intrasurgical spectral domain optical coherence tomography during macular surgery in a prospective monocenter study. Before pars plana vitrectomy and before, during, and after membrane peeling, 512 × 128 macular cube scans were performed using a Carl Zeiss Meditec Cirrus high-definition OCT system adapted to the optical pathway of a Zeiss OPMI VISU 200 surgical microscope and compared with retinal staining. The study included 51 patients with epiretinal membranes, with 8 of those having additional lamellar macular holes, 11 patients with vitreomacular traction, and 8 patients with full-thickness macular holes. Intraoperative spectral domain optical coherence tomography allowed performing membrane peeling without using retinal dyes in 40% of cases (28 of 70 patients). No residual membranes were found in 94.3% of patients (66 of 70 patients) in intrasurgical spectral domain optical coherence tomography and subsequent (re)staining. In patients with vitreomacular traction, intrasurgical spectral domain optical coherence tomography scans facilitated decisions on the need for an intraocular tamponade after membrane peeling. Intraoperative spectral domain optical coherence tomography was comparable with retinal dyes in confirming success after membrane peeling. However, the visualization of flat membranes was better after staining.

  12. Resultado funcional e índice macular em portadores de buraco macular submetidos à cirurgia com remoção da membrana limitante interna Functional outcome and macular index in macular hole patients who underwent surgery with internal limiting membrane removal

    Directory of Open Access Journals (Sweden)

    José Ricardo Diniz

    2008-04-01

    Full Text Available OBJETIVOS: Avaliar o resultado funcional e o índice macular dos portadores de buraco macular submetidos à cirurgia com remoção da membrana limitante interna. MÉTODOS: Quinze olhos de 15 pacientes com buraco macular estágios 2, 3 e 4 foram incluídos no estudo. Todos foram submetidos à cirurgia de buraco macular convencional com remoção da membrana limitante interna corada pelo azul de tripan. Melhor acuidade visual com correção e cortes transversais medidos por tomografia de coerência óptica (OCT foram avaliados no pré- e pós-operatório. O índice macular (razão entre a altura e base do buraco macular foi calculado e correlacionado com o diâmetro mínimo do buraco macular e o ganho de acuidade visual pós-operatória. RESULTADOS: Obteve-se fechamento do buraco macular em todos pacientes operados. Em 86,7%, houve ganho de pelo menos três linhas de visão. O índice macular demonstrou correlação negativa significante com o diâmetro mínimo (r=0,811. Não foi observada correlação significante entre o índice macular e o ganho de acuidade visual pós-operatória (r=0,351. CONCLUSÃO: Os resultados funcionais na cirurgia do buraco macular com remoção da membrana limitante interna foram bons neste grupo de pacientes. O índice macular demonstrou ser compatível com a configuração espacial do buraco macular, porém não foi preditor de resultados visuais.PURPOSE: To evaluate the functional outcome and macular index in patients with macular hole who underwent surgery with internal limiting membrane removal. METHODS: Fifteen eyes of 15 patients with idiopathic macular hole stages 2, 3 or 4 were enrolled in this study. All patients underwent conventional macular hole surgery with trypan blue staining to remove the internal limiting membrane. The best-corrected visual acuity and cross-sectional images of macular hole measured by optical coherence tomography (OCT were evaluated pre- and postoperatively. The macular hole index

  13. Enhanced water collection through a periodic array of tiny holes in dropwise condensation

    Science.gov (United States)

    Song, Kyungjun; Kim, Gyeonghee; Oh, Sunjong; Lim, Hyuneui

    2018-02-01

    This paper introduces a simple method of water collection by increasing the coalescence effects in dropwise condensation with the use of microscale holes. The tiny holes modified the surface free energy states of the droplets on the plate, yielding a surface free energy barrier between the flat solid surface and the holes. The spatial difference in the surface free energy of the droplets enabled the droplets to move toward the adjacent droplets, thus increasing the possibility of coalescence. The water collection experiments were performed using a Peltier-based cooling system at 2 °C inside a chamber at 30 °C and 70% humidity. The results demonstrated that the perforated plates without any additional treatment provided the water collection rate of up to 22.64 L/m2 day, which shows an increase of 30% compared to that demonstrated by the bare plate. By comparing the experimental results for the surface of filmwise condensation, it was proved that the dominant water collecting improvement results from the increased coalescence effects. This simple technique can enhance the performance of systems exposed to water condensation, including water collection, heat-transfer, and dehumidifying systems.

  14. Comparisons of retinal nerve fiber layer thickness changes after macular hole surgery

    Directory of Open Access Journals (Sweden)

    Nelson Chamma Capelanes

    Full Text Available ABSTRACT Purpose: To compare postoperative changes in retinal nerve fiber layer thickness in patients with macular holes treated with vitrectomy with Brilliant Blue-assisted internal limiting membrane peeling. Methods: Twenty-two eyes of 20 patients with macular holes were studied. Each eye was selected to undergo Brilliant Blue-assisted internal limiting membrane peeling. The circumferential retinal nerve fiber layer thickness was determined using spectral domain optical coherence tomography preoperatively and 2 months postoperatively. Mean overall and sectoral retinal nerve fiber layer thicknesses were obtained for each patient. Results: There was no statistically significant difference (p≥0.05 between the pre- and post-treatment measurements in relation to each CFN variable, i.e., on average, pre-treatment measures were the same as post-treatment measures. Furthermore, despite the differences between the pre- and post-treatment measures always being positive (pre-post >0, they are not statistically significant. Conclusions: This study showed no significant decrease in retinal nerve fiber layer thickness measurements after macular holes surgery, regardless of age or sex.

  15. Microwave response of hole and patch arrays

    Science.gov (United States)

    Taylor, Melita C.; Edmunds, James D.; Hendry, Euan; Hibbins, Alastair P.; Sambles, J. Roy

    2010-10-01

    The electromagnetic response of two-dimensional square arrays of perfectly conducting square patches, and their complementary structures, is modeled utilizing a modal matching technique and employing Babinet’s principle. This method allows for the introduction of progressively higher diffracted orders and waveguide modes to be included in the calculation, hence aiding understanding of the underlying causal mechanism for the observed response. At frequencies close to, but below, the onset of diffraction, a near-complete reflection condition is predicted, even for low filling fractions: conversely, for high filling fractions a near-complete transmission condition results. These resonance phenomena are associated with evanescent diffraction, which is sufficiently strong to reverse the step change in transmission upon establishment of electrical continuity; i.e., the connected structure demonstrates increased transmission with increasing filling fraction.

  16. Cost-effectiveness of internal limiting membrane peeling versus no peeling for patients with an idiopathic full-thickness macular hole: results from a randomised controlled trial.

    Science.gov (United States)

    Ternent, Laura; Vale, Luke; Boachie, Charles; Burr, Jennifer M; Lois, Noemi

    2012-03-01

    To determine whether internal limiting membrane (ILM) peeling is cost-effective compared with no peeling for patients with an idiopathic stage 2 or 3 full-thickness macular hole. A cost-effectiveness analysis was performed alongside a randomised controlled trial. 141 participants were randomly allocated to receive macular-hole surgery, with either ILM peeling or no peeling. Health-service resource use, costs and quality of life were calculated for each participant. The incremental cost per quality-adjusted life year (QALY) gained was calculated at 6 months. At 6 months, the total costs were on average higher (£424, 95% CI -182 to 1045) in the No Peel arm, primarily owing to the higher reoperation rate in the No Peel arm. The mean additional QALYs from ILM peel at 6 months were 0.002 (95% CI 0.01 to 0.013), adjusting for baseline EQ-5D and other minimisation factors. A mean incremental cost per QALY was not computed, as Peeling was on average less costly and slightly more effective. A stochastic analysis suggested that there was more than a 90% probability that Peeling would be cost-effective at a willingness-to-pay threshold of £20,000 per QALY. Although there is no evidence of a statistically significant difference in either costs or QALYs between macular hole surgery with or without ILM peeling, the balance of probabilities is that ILM Peeling is likely to be a cost-effective option for the treatment of macular holes. Further long-term follow-up data are needed to confirm these findings.

  17. 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.

  18. Microfabricated hollow microneedle array using ICP etcher

    International Nuclear Information System (INIS)

    Ji Jing; Tay, Francis E H; Miao Jianmin

    2006-01-01

    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 6 /O 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

  19. 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.

  20. The Nernst theorem and statistical entropy in a (1+1)-dimensional charged black hole

    International Nuclear Information System (INIS)

    Ren, Z.; Junfang, Z.; Lichun, Z.

    2001-01-01

    It was derived that the bosonic and fermionic entropies in (1+1)-dimensional charged black hole directly by using the quantum statistical method. The result is the same as the integral expression obtained by solving the wave equation approximately. Then it is obtained the statistical entropy of the black hole by integration via the improved brick-wall method, membrane model. The derived entropy satisfies the thermodynamic relation. When the radiation temperature of the black hole tends to zero, so does the entropy. It obeys Nernst theorem. So it can be taken as Planck absolute entropy

  1. Unstable ‘black branes’ from scaled membranes at large D

    Energy Technology Data Exchange (ETDEWEB)

    Dandekar, Yogesh; Mazumdar, Subhajit; Minwalla, Shiraz; Saha, Arunabha [Department of Theoretical Physics, Tata Institute of Fundamental Research,Homi Bhabha Road, Mumbai, 400005 (India)

    2016-12-28

    It has recently been demonstrated that the dynamics of black holes at large D can be recast as a set of non gravitational membrane equations. These membrane equations admit a simple static solution with shape S{sup D−p−2}×R{sup p,1}. In this note we study the equations for small fluctuations about this solution in a limit in which amplitude and length scale of the fluctuations are simultaneously scaled to zero as D is taken to infinity. We demonstrate that the resultant nonlinear equations, which capture the Gregory-Laflamme instability and its end point, exactly agree with the effective dynamical ‘black brane’ equations of Emparan Suzuki and Tanabe. Our results thus identify the ‘black brane’ equations as a special limit of the membrane equations and so unify these approaches to large D black hole dynamics.

  2. Retinal Damage Induced by Internal Limiting Membrane Removal

    Directory of Open Access Journals (Sweden)

    Rachel Gelman

    2015-01-01

    Full Text Available The internal limiting membrane (ILM, the basement membrane of the Müller cells, serves as the interface between the vitreous body and the retinal nerve fiber layer. It has a fundamental role in the development, structure, and function of the retina, although it also is a pathologic component in the various vitreoretinal disorders, most notably in macular holes. It was not until understanding of the evolution of idiopathic macular holes and the advent of idiopathic macular hole surgery that the idea of adjuvant ILM peeling in the treatment of tractional maculopathies was explored. Today intentional ILM peeling is a commonly applied surgical technique among vitreoretinal surgeons as it has been found to increase the rate of successful macular hole closure and improve surgical outcomes in other vitreoretinal diseases. Though ILM peeling has refined surgery for tractional maculopathies, like all surgical procedures it is not immune to perioperative risk. The essential role of the ILM to the integrity of the retina and risk of trauma to retinal tissue spurs suspicion with regard to its routine removal. Several authors have investigated the retinal damage induced by ILM peeling and these complications have been manifested across many different diagnostic studies.

  3. A facile and efficient approach for pore-opening detection of anodic aluminum oxide membranes

    Science.gov (United States)

    Cui, Jiewu; Wu, Yucheng; Wang, Yan; Zheng, Hongmei; Xu, Guangqing; Zhang, Xinyi

    2012-05-01

    The well aligned porous anodic aluminum oxide (AAO) membrane is fabricated by a two-step anodization method. The oxide barrier layer of AAO membrane must be removed to get through-hole membrane for synthesizing nanowires and nanotubes of metals, semiconductors and conducting polymers. Removal of the barrier layer of oxide and pore-extending is of significant importance for the preparation of AAO membrane with through-hole pore morphology and desired pore diameter. The conventional method for pore opening is that AAO membrane after removing of aluminum substrate is immersed in chemical etching solution, which is completely empirical and results in catastrophic damage for AAO membrane frequently. A very simple and efficient approach based on capillary action for detecting pore opening of AAO membrane is introduced in this paper, this method can achieve the detection for pore opening visually and control the pore diameter precisely to get desired morphology and the pore diameter of AAO membrane. Two kinds of AAO membranes with different pore shape were obtained by different pore opening methods. In addition, one-dimensional gradient gold nanowires are also fabricated by electrodeposition based on AAO membranes.

  4. Machining of the nuclear tube sheet with small hole diameter

    International Nuclear Information System (INIS)

    Lin Lifeng

    2010-01-01

    Regarding the tube sheet for the heat exchanger of Qinshan Phase II extension project, its material is 00Cr19Ni10 forgings, the tube sheet thickness is 125 mm, requiring 178-φ10.35 0 +0.05 hole, the tube array shall take the shape of equilateral triangle, the center distance is 15 mm, and the tube hole roughness is Ra 3.2. The guide sleeve shall be adopted for positioning prior to machining of the high precision small hole of the thick tube sheet, and the gun drill and BTA drill shall be adopted for testing, finally BTA drilling with internal chip removal shall be adopted, this method shall overcome the disadvantage factor of BTA drilling and shall be the new approach for drilling. The diameter of BTA drill is φ10.34 mm. The machined hole diameter shall be φ10.375-φ10.355 mm. The ellipticity of the tube hole shall be less than 0.01 mm, the pipe bridge dimension shall be 4.6 mm, conforming to the requirement of the drawing. The paper presents the precautions during machining so as to provide the reference for the similar pipe hole machining in the future. (author)

  5. A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

    International Nuclear Information System (INIS)

    Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang

    2016-01-01

    Highlights: • A general melt-injection-decomposition (MID) route is proposed for the fabrication of oriented metal oxide nanowire arrays. • Four kinds of metal oxide (CuO, Mn_2O_3, Co_3O_4 and Cr_2O_3) nanowire arrays have been realized as examples through the developed MID route. • The mechanism of the developed MID route is discussed using Thermogravimetry and Differential Thermal Analysis technique. • The MID route is a versatile, simple, facile and effective way to prepare different kinds of oriented metal oxide nanowire arrays in the future. - Abstract: In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn_2O_3, Co_3O_4 and Cr_2O_3) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

  6. Displacement of foveal area toward optic disc after macular hole surgery with internal limiting membrane peeling.

    Science.gov (United States)

    Kawano, K; Ito, Y; Kondo, M; Ishikawa, K; Kachi, S; Ueno, S; Iguchi, Y; Terasaki, H

    2013-07-01

    To determine whether there is a displacement of the fovea toward the optic disc after successful macular hole (MH) surgery with internal limiting membrane (ILM) peeling. The medical records of 54 eyes of 53 patients that had undergone pars plana vitrectomy with ILM peeling and gas or air tamponade for an idiopathic MH were evaluated. Spectral-domain optical coherence tomography (OCT) had been performed before and >6 months after the surgery. The preoperative distances between the center of the MH and the optic disc (MH-OD), center of the MH and the bifurcation or crossing of retinal vessels (MH-RV) were measured in the OCT images. In addition, the postoperative distance between the center of the fovea and optic disc (F-OD) and the center of the fovea and the same bifurcation or crossing of retinal vessels (F-RV) were measured in the OCT images. The F-OD was 2.67±0.33 disc diameters (DD), which was significantly shorter than that of the MH-OD of 2.77±0.33 DD (Pdisplacement of the center of the macula toward the optic disc.

  7. VLBA Reveals Closest Pair of Supermassive Black Holes

    Science.gov (United States)

    2006-05-01

    Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope have found the closest pair of supermassive black holes ever discovered in the Universe -- a duo of monsters that together are more than 150 million times more massive than the Sun and closer together than the Earth and the bright star Vega. The VLBA The VLBA CREDIT: NRAO/AUI/NSF "These two giant black holes are only about 24 light-years apart, and that's more than 100 times closer than any pair found before," said Cristina Rodriguez, of the University of New Mexico (UNM) and Simon Bolivar University in Venezuela. Black holes are concentrations of mass with gravity so strong that not even light can escape them. The black hole pair is in the center of a galaxy called 0402+379, some 750 million light-years from Earth. Astronomers presume that each of the supermassive black holes was once at the core of a separate galaxy, then the two galaxies collided, leaving the black holes orbiting each other. The black holes orbit each other about once every 150,000 years, the scientists say. "If two black holes like these were to collide, that event would create the type of strong gravitational waves that physicists hope to detect with instruments now under construction," said Gregory Taylor, of UNM. The physicists will need to wait, though: the astronomers calculate that the black holes in 0402+379 won't collide for about a billion billion years. "There are some things that might speed that up a little bit," Taylor remarked. An earlier VLBA study of 0402+379, an elliptical galaxy, showed the pair of radio-wave-emitting objects near its core. Further studies using the VLBA and the Hobby-Eberly Telescope in Texas, revealed that the pair of objects is indeed a pair of supermassive black holes. "We needed the ultra-sharp radio 'vision' of the VLBA, particularly at the high radio frequencies of 22 and 43 GigaHertz, to get the detail needed to show that those objects are a pair of

  8. Capacitance of a highly ordered array of nanocapacitors: Model and microscopy

    Science.gov (United States)

    Cortés, A.; Celedón, C.; Ulloa, P.; Kepaptsoglou, D.; Häberle, P.

    2011-11-01

    This manuscript describes briefly the process used to build an ordered porous array in an anodic aluminum oxide (AAO) membrane, filled with multiwall carbon nanotubes (MWCNTs). The MWCNTs were grown directly inside the membrane through chemical vapor deposition (CVD). The role of the CNTs is to provide narrow metal electrodes contact with a dielectric surface barrier, hence, forming a capacitor. This procedure allows the construction of an array of 1010 parallel nano-spherical capacitors/cm2. A central part of this contribution is the use of physical parameters obtained from processing transmission electron microscopy (TEM) images, to predict the specific capacitance of the AAOs arrays. Electrical parameters were obtained by solving Laplace's equation through finite element methods (FEMs).

  9. White holes and eternal black holes

    International Nuclear Information System (INIS)

    Hsu, Stephen D H

    2012-01-01

    We investigate isolated white holes surrounded by vacuum, which correspond to the time reversal of eternal black holes that do not evaporate. We show that isolated white holes produce quasi-thermal Hawking radiation. The time reversal of this radiation, incident on a black hole precursor, constitutes a special preparation that will cause the black hole to become eternal. (paper)

  10. Persistent hole-burning of perylene microcrystallites dispersed in PVA

    International Nuclear Information System (INIS)

    Mizuno, K.; Matsubara, T.; Sugahara, K.; Aoki-Matsumoto, T.; Ichida, M.; Ando, H.; Itoh, T.

    2011-01-01

    A persistent hole-burning is observed in β-perylene microcrystallites, which were embedded in poly-vinyl alcohol. By laser light excitation at 22,535 cm -1 and at 10 K, the hole is found at the excitation photon energy. The mechanism of the persistent hole-burning is interpreted in terms of the resolution of microcrystallites into smaller microcrystallites. This is a novel observation of the persistent hole-burning in aromatic microcrystallites. When the specimen, which includes a hole, is annealed at high temperatures, the resolved microcrystallites restore back to the old position as had been. The β-perylene microcrystallite specimen that we have grown was as small as 1.5 nm in average diameter. They are one order smaller in number of molecules included, compared to those that have been reported on aromatic microcrystallites, anthracene for example. Due to this, we were able to observe the 0-0 transition energy, which varied according as the number of molecules involved in the microcrystallites. We also observed the 0-0 absorption (excitation) spectrum, which depends on the molecular arrays in the microcrystallites. The 0-0 transition of a single molecule in poly-vinyl alcohol matrix is anticipated to be located at 22,885 cm -1 .

  11. Photovoltaic array with minimally penetrating rooftop support system

    Science.gov (United States)

    Lenox, Carl J.S.

    2012-10-23

    A photovoltaic array including a plurality of photovoltaic assemblies and a plurality of mounting units. The mounting units each include an elongate rail and a plurality of leg assemblies. The rail is sized and configured to maintain a portion of at least two of the photovoltaic assemblies, with the leg assemblies extending from the rail in a spaced-apart fashion and terminating in a foot for placement against a rooftop structure for minimally penetration installation. Further, at least one of the leg assemblies can include a retractable leg. When the photovoltaic array is installed to a rooftop structure including a membrane intermittently secured to a rooftop deck, the retractable leg accommodates upward billowing of the membrane under windy conditions.

  12. Preparation and characterization of CuO nanowire arrays

    International Nuclear Information System (INIS)

    Yu Dongliang; Ge Chuannan; Du Youwei

    2009-01-01

    CuO nanowire arrays were prepared by oxidation of copper nanowires embedded in anodic aluminum oxide (AAO) membranes. The AAO was fabricated in an oxalic acid at a constant voltage. Copper nanowires were formed in the nanopores of the AAO membranes in an electrochemical deposition process. The oxidized copper nanowires at different temperatures were studied. X-ray diffraction patterns confirmed the formation of a CuO phase after calcining at 500 0 C in air for 30 h. A transmission electron microscopy was used to characterize the nanowire morphologies. Raman spectra were performed to study the CuO nanowire arrays. After measuring, we found that the current-voltage curve of the CuO nanowires is nonlinear.

  13. Fabrication of nanopore and nanoparticle arrays with high aspect ratio AAO masks

    Science.gov (United States)

    Li, Z. P.; Xu, Z. M.; Qu, X. P.; Wang, S. B.; Peng, J.; Mei, L. H.

    2017-03-01

    How to use high aspect ratio anodic aluminum oxide (AAO) membranes as an etching and evaporation mask is one of the unsolved problems in the application of nanostructured arrays. Here we describe the versatile utilizations of the highly ordered AAO membranes with a high aspect ratio of more than 20 used as universal masks for the formation of various nanostructure arrays on various substrates. The result shows that the fabricated nanopore and nanoparticle arrays of substrates inherit the regularity of the AAO membranes completely. The flat AAO substrates and uneven AAO frontages were attached to the Si substrates respectively as an etching mask, which demonstrates that the two kinds of replication, positive and negative, represent the replication of the mirroring of Si substrates relative to the flat AAO substrates and uneven AAO frontages. Our work is a breakthrough for the broad research field of surface nano-masking.

  14. Preparation of Track Etch Membrane Filters Using Polystyrene Film

    International Nuclear Information System (INIS)

    Kaewsaenee, Jerawut; Ratanatongchai, Wichian; Supaphol, Pitt; Visal-athaphand, Pinpan

    2007-08-01

    Full text: Polystyrene nuclear track etch membrane filters was prepared by exposed 13 .m thin film polystyrene with fission fragment. Nuclear latent track was enlarged to through hole on the film by etching with 80 o C 40% H 2 SO 4 with K 2 Cr 2 O 7 solution for 6-10 hour. The hole size was depend on concentration of etching solution and etching time with 1.3-3.4 .m hole diameter. The flow rate test of water was 0.79-1.56 mm cm-2 min-1 at 109.8-113.7 kPa pressure

  15. Nernst Theorem and Statistical Entropy of 5-Dimensional Rotating Black Hole

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ren; WU Yue-Qin; ZHANG Li-Chun

    2003-01-01

    In this paper, by using quantum statistical method, we obtain the partition function of Bose field and Fermi field on the background of the 5-dimensional rotating black hole. Then via the improved brick-wall method and membrane model, we calculate the entropy of Bose field and Fermi field of the black hole. And it is obtained that the entropy of the black hole is not only related to the area of the outer horizon but also is the function of inner horizon's area. In our results, there are not the left out term and the divergent logarithmic term in the original brick-wall method.The doubt that why the entropy of the scalar or Dirac field outside the event horizon is the entropy of the black hole in the original brick-wall method does not exist. The influence of spinning degeneracy of particles on entropy of the black hole is also given. It is shown that the entropy determined by the areas of the inner and outer horizons will approach zero,when the radiation temperature of the black hole approaches absolute zero. It satisfies Nernst theorem. The entropy can be taken as the Planck absolute entropy. We provide a way to study higher dimensional black hole.

  16. Entropy of Reissner-Nordstrom-De Sitter Black Hole in Nonthermal Equilibrium

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ren; ZHANG Jun-Fang; ZHANG Li-Chun

    2002-01-01

    By making use of the method of quantum statistics, we directly derive the partition function of bosonic and fermionic fields in Reissner-Nordstrom-De Sitter black hole and obtain the integral expression of black hole's entropy and the entropy to which the cosmic horizon surface corresponds. It avoids the difficulty in solving the wave equation of various particles. Then via the improved brick-wall method, i.e. the membrane model, we calculate black hole's entropy and cosmic entropy and find out that if we let the integral upper limit and lower limit both tend to the horizon, the entropy of black hole is proportional to the area of horizon and the entropy to which cosmic horizon surface corresponds is proportional to the area of cosmic horizon. In our result, the stripped term and the divergent logarithmic term in the original brick-wall method no longer exist. In the whole process, the physical idea is clear and the calculation is simple.We offer a new simple and direct way for calculating the entropy of different complicated black holes.

  17. The highly efficient photocatalytic and light harvesting property of Ag-TiO2 with negative nano-holes structure inspired from cicada wings.

    Science.gov (United States)

    Zada, Imran; Zhang, Wang; Zheng, Wangshu; Zhu, Yuying; Zhang, Zhijian; Zhang, Jianzhong; Imtiaz, Muhammad; Abbas, Waseem; Zhang, Di

    2017-12-08

    The negative replica of biomorphic TiO 2 with nano-holes structure has been effectively fabricated directly from nano-nipple arrays structure of cicada wings by using a simple, low-cost and highly effective sol-gel ultrasonic method. The nano-holes array structure was well maintained after calcination in air at 500 °C. The Ag nanoparticles (10 nm-25 nm) were homogeneously decorated on the surface and to the side wall of nano-holes structure. It was observed that the biomorphic Ag-TiO 2 showed remarkable photocatalytic activity by degradation of methyl blue (MB) under UV-vis light irradiation. The biomorphic Ag-TiO 2 with nano-holes structure showed superior photocatalytic activity compared to the biomorphic TiO 2 and commercial Degussa P25. This high-performance photocatalytic activity of the biomorphic Ag-TiO 2 may be attributed to the nano-holes structure, localized surface plasmon resonance (LSPR) property of the Ag nanoparticles, and enhanced electron-hole separation. Moreover, the biomorphic Ag-TiO 2 showed more absorption capability in the visible wavelength range. This work provides a new insight to design such a structure which may lead to a range of novel applications.

  18. A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang, E-mail: sgyang@nju.edu.cn

    2016-12-30

    Highlights: • A general melt-injection-decomposition (MID) route is proposed for the fabrication of oriented metal oxide nanowire arrays. • Four kinds of metal oxide (CuO, Mn{sub 2}O{sub 3}, Co{sub 3}O{sub 4} and Cr{sub 2}O{sub 3}) nanowire arrays have been realized as examples through the developed MID route. • The mechanism of the developed MID route is discussed using Thermogravimetry and Differential Thermal Analysis technique. • The MID route is a versatile, simple, facile and effective way to prepare different kinds of oriented metal oxide nanowire arrays in the future. - Abstract: In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn{sub 2}O{sub 3}, Co{sub 3}O{sub 4} and Cr{sub 2}O{sub 3}) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

  19. High-definition polymeric membranes: construction of 3D lithographed channel arrays through control of natural building blocks dynamics.

    Science.gov (United States)

    Speranza, Valentina; Trotta, Francesco; Drioli, Enrico; Gugliuzza, Annarosa

    2010-02-01

    The fabrication of well-defined interfaces is in high demand in many fields of biotechnologies. Here, high-definition membrane-like arrays are developed through the self-assembly of water droplets, which work as natural building blocks for the construction of ordered channels. Solution viscosity together with the dynamics of the water droplets can decide the final formation of three-dimensional well-ordered patterns resembling anodic structures, especially because solvents denser than water are used. Particularly, the polymer solution viscosity is demonstrated to be a powerful tool for control of the mobility of submerged droplets during the microfabrication process. The polymeric patterns are structured at very high levels of organization and exhibit well-established transport-surface property relationships, considered basics for any types of advanced biotechnologies.

  20. Evaluation of two membrane-based microextraction techniques for the determination of endocrine disruptors in aqueous samples by HPLC with diode array detection.

    Science.gov (United States)

    Luiz Oenning, Anderson; Lopes, Daniela; Neves Dias, Adriana; Merib, Josias; Carasek, Eduardo

    2017-11-01

    In this study, the viability of two membrane-based microextraction techniques for the determination of endocrine disruptors by high-performance liquid chromatography with diode array detection was evaluated: hollow fiber microporous membrane liquid-liquid extraction and hollow-fiber-supported dispersive liquid-liquid microextraction. The extraction efficiencies obtained for methylparaben, ethylparaben, bisphenol A, benzophenone, and 2-ethylhexyl-4-methoxycinnamate from aqueous matrices obtained using both approaches were compared and showed that hollow fiber microporous membrane liquid-liquid extraction exhibited higher extraction efficiency for most of the compounds studied. Therefore, a detailed optimization of the extraction procedure was carried out with this technique. The optimization of the extraction conditions and liquid desorption were performed by univariate analysis. The optimal conditions for the method were supported liquid membrane with 1-octanol for 10 s, sample pH 7, addition of 15% w/v of NaCl, extraction time of 30 min, and liquid desorption in 150 μL of acetonitrile/methanol (50:50 v/v) for 5 min. The linear correlation coefficients were higher than 0.9936. The limits of detection were 0.5-4.6 μg/L and the limits of quantification were 2-16 μg/L. The analyte relative recoveries were 67-116%, and the relative standard deviations were less than 15.5%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Exploring Jets from a Supermassive Black Hole

    Science.gov (United States)

    Kohler, Susanna

    2018-06-01

    What are the feeding and burping habits of the supermassive black holes peppering the universe? In a new study, observations of one such monster reveal more about the behavior of its powerful jets.Beams from BehemothsAcross the universe, supermassive black holes of millions to billions of solar masses lie at the centers of galaxies, gobbling up surrounding material. But not all of the gas and dust that spirals in toward a black hole is ultimately swallowed! A large fraction of it can instead be flung out into space again, in the form of enormous, powerful jets that extend for thousands or even millions of light-years in opposite directions.M87, shown in this Hubble image, is a classic example of a nearby (55 million light-years distant) supermassive black hole with a visible, collimated jet. Its counter-jet isnt seen because relativistic effects make the receding jet appear less bright. [The Hubble Heritage Team (STScI/AURA) and NASA/ESA]What causes these outflows to be tightly beamed collimated in the form of jets, rather than sprayed out in all directions? Does the pressure of the ambient medium the surrounding gas and dust that the jet is injected into play an important role? In what regions do these jets accelerate and decelerate? There are many open questions that scientists hope to understand by studying some of the active black holes with jets that live closest to us.Eyes on a Nearby GiantIn a new study led by Satomi Nakahara (The Graduate University for Advanced Studies in Japan), a team of scientists has used multifrequency Very Long Baseline Array (VLBA) and Very Long Array (VLA) images to explore jets emitted from a galaxy just 100 million light-years away: NGC 4261.This galaxys (relatively) close distance as well as the fact that were viewing it largely from the side, so we can clearly see both of its polar jets allows us to observe in detail the structure and intensity of its jets as a function of their distance from the black hole. Nakahara and

  2. INDUCTION OF MACULAR DETACHMENT FOR THE TREATMENT OF PERSISTENT OR RECURRENT IDIOPATHIC MACULAR HOLES.

    Science.gov (United States)

    Szigiato, Andrei-Alexandru; Gilani, Fatimah; Walsh, Mark K; Mandelcorn, Efrem D; Muni, Rajeev H

    2016-09-01

    To analyze the efficacy of induced macular detachment for the treatment of persistent or recurrent idiopathic macular holes after treatment with one or more standard pars plana vitrectomies (PPVs) with internal limiting membrane peeling. This study is a retrospective consecutive case series of 10 patients who underwent a PPV with subretinal balanced salt solution injection from 2011 to 2014 to treat persistent or recurrent idiopathic macular holes. All patients had previously undergone PPV with internal limiting membrane peeling. Visual acuity, ocular examination findings, and optical coherence tomographic images were reviewed preoperatively and postoperatively to assess the anatomical and visual outcomes of this procedure. Nine of the 10 patients who underwent the procedure had closure of their macular holes postoperatively (90%) and remained closed 6 months postoperatively. Most patients reported a subjective visual improvement. A mean objective visual improvement of 16 letters (Early Treatment Diabetic Retinopathy Study, 0.324 logMAR) was seen between preoperative and 6-month postoperative assessments of all patients (pre = 1.490, post = 1.166; P = 0.022). Subgroup analysis of patients with successful closure revealed 20 letters of improvement (0.398 logMAR) in visual acuity (pre = 1.491, post = 1.093; P = 0.004). There were no intraoperative or postoperative complications. In eyes with persistent or recurrent idiopathic macular holes after standard PPV with internal limiting membrane peeling, repeat PPV with subretinal balanced salt solution injection to create a macular detachment may be a viable surgical treatment option. Our results show improved anatomical and visual outcomes postoperatively that compare favorably to other case series describing various surgical treatments for these challenging cases.

  3. Localised electrochemical impedance measurements of a polymer electrolyte fuel cell using a reference electrode array to give cathode-specific measurements and examine membrane hydration dynamics

    Science.gov (United States)

    Engebretsen, Erik; Hinds, Gareth; Meyer, Quentin; Mason, Tom; Brightman, Edward; Castanheira, Luis; Shearing, Paul R.; Brett, Daniel J. L.

    2018-04-01

    Advances in bespoke diagnostic techniques for polymer electrolyte fuel cells continue to provide unique insight into the internal operation of these devices and lead to improved performance and durability. Localised measurements of current density have proven to be extremely useful in designing better fuel cells and identifying optimal operating strategies, with electrochemical impedance spectroscopy (EIS) now routinely used to deconvolute the various losses in fuel cells. Combining the two techniques provides another dimension of understanding, but until now each localised EIS has been based on 2-electrode measurements, composed of both the anode and cathode responses. This work shows that a reference electrode array can be used to give individual electrode-specific EIS responses, in this case the cathode is focused on to demonstrate the approach. In addition, membrane hydration dynamics are studied under current load steps from open circuit voltage. A three-stage process is identified associated with an initial rapid reduction in membrane resistance after 10 s of applying a current step, followed by a slower ramp to approximately steady state, which was achieved after ∼250 s. These results support previously published work that has looked at membrane swelling dynamics and reveal that membrane hydration/membrane resistance is highly heterogeneous.

  4. A hierarchically assembled mesoporous ZnO hemisphere array and hollow microspheres for photocatalytic membrane water filtration.

    Science.gov (United States)

    Pan, Jia Hong; Zhang, Xiwang; Du, Alan J; Bai, Hongwei; Ng, Jiawei; Sun, Darren

    2012-05-28

    A mesoporous ZnO hemisphere array has been prepared via a topotactic transition of Zn(4)(OH)(6)CO(3)·H(2)O (ZCHH) by chemical bath deposition. Each hemisphere is comprised of a radially oriented nanoflake shell grown on the hemispherical interior. Reaction time-dependent SEM analysis shows that the morphological formation of ZCHH involves a deposition-growth-secondary growth-redeposition procedure. Upon calcination, ZCHH readily decomposes to nanocrystalline wurtzite-phase ZnO without significant change in morphology, and the release of CO(2) and H(2)O from ZCHH creates an additional mesoporous structure in both hemispherical interior and nanoflake shell. A similar process but without using a substrate has been developed for synthesis of mesoporous ZnO hollow microspheres in powder form. Both the elaborated superstructured photocatalysts consisting of mesoporous nanoflakes have been demonstrated to exhibit excellent performances in the photocatalytic membrane filtration.

  5. SWNT array resonant gate MOS transistor.

    Science.gov (United States)

    Arun, A; Campidelli, S; Filoramo, A; Derycke, V; Salet, P; Ionescu, A M; Goffman, M F

    2011-02-04

    We show that thin horizontal arrays of single wall carbon nanotubes (SWNTs) suspended above the channel of silicon MOSFETs can be used as vibrating gate electrodes. This new class of nano-electromechanical system (NEMS) combines the unique mechanical and electronic properties of SWNTs with an integrated silicon-based motion detection. Its electrical response exhibits a clear signature of the mechanical resonance of SWNT arrays (120-150 MHz) showing that these thin horizontal arrays behave as a cohesive, rigid and elastic body membrane with a Young's modulus in the order of 1-10 GPa and ultra-low mass. The resonant frequency can be tuned by the gate voltage and its dependence is well understood within the continuum mechanics framework.

  6. SWNT array resonant gate MOS transistor

    International Nuclear Information System (INIS)

    Arun, A; Salet, P; Ionescu, A M; Campidelli, S; Filoramo, A; Derycke, V; Goffman, M F

    2011-01-01

    We show that thin horizontal arrays of single wall carbon nanotubes (SWNTs) suspended above the channel of silicon MOSFETs can be used as vibrating gate electrodes. This new class of nano-electromechanical system (NEMS) combines the unique mechanical and electronic properties of SWNTs with an integrated silicon-based motion detection. Its electrical response exhibits a clear signature of the mechanical resonance of SWNT arrays (120-150 MHz) showing that these thin horizontal arrays behave as a cohesive, rigid and elastic body membrane with a Young's modulus in the order of 1-10 GPa and ultra-low mass. The resonant frequency can be tuned by the gate voltage and its dependence is well understood within the continuum mechanics framework.

  7. Transparent Nanopore Cavity Arrays Enable Highly Parallelized Optical Studies of Single Membrane Proteins on Chip.

    Science.gov (United States)

    Diederichs, Tim; Nguyen, Quoc Hung; Urban, Michael; Tampé, Robert; Tornow, Marc

    2018-06-13

    Membrane proteins involved in transport processes are key targets for pharmaceutical research and industry. Despite continuous improvements and new developments in the field of electrical readouts for the analysis of transport kinetics, a well-suited methodology for high-throughput characterization of single transporters with nonionic substrates and slow turnover rates is still lacking. Here, we report on a novel architecture of silicon chips with embedded nanopore microcavities, based on a silicon-on-insulator technology for high-throughput optical readouts. Arrays containing more than 14 000 inverted-pyramidal cavities of 50 femtoliter volumes and 80 nm circular pore openings were constructed via high-resolution electron-beam lithography in combination with reactive ion etching and anisotropic wet etching. These cavities feature both, an optically transparent bottom and top cap. Atomic force microscopy analysis reveals an overall extremely smooth chip surface, particularly in the vicinity of the nanopores, which exhibits well-defined edges. Our unprecedented transparent chip design provides parallel and independent fluorescent readout of both cavities and buffer reservoir for unbiased single-transporter recordings. Spreading of large unilamellar vesicles with efficiencies up to 96% created nanopore-supported lipid bilayers, which are stable for more than 1 day. A high lipid mobility in the supported membrane was determined by fluorescent recovery after photobleaching. Flux kinetics of α-hemolysin were characterized at single-pore resolution with a rate constant of 0.96 ± 0.06 × 10 -3 s -1 . Here, we deliver an ideal chip platform for pharmaceutical research, which features high parallelism and throughput, synergistically combined with single-transporter resolution.

  8. Metal membrane with dimer slots as a universal polarizer

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Zalkovskij, Maksim; Malureanu, Radu

    2014-01-01

    In this work, we show theoretically and confirm experimentally that thin metal membranes patterned with an array of slot dimers (or their Babinet analogue with metal rods) can function as a versatile spectral and polarization filter. We present a detailed covariant multipole theory for the electr......In this work, we show theoretically and confirm experimentally that thin metal membranes patterned with an array of slot dimers (or their Babinet analogue with metal rods) can function as a versatile spectral and polarization filter. We present a detailed covariant multipole theory...

  9. Integration of membrane filtration and photoelectrocatalysis using a TiO{sub 2}/carbon/Al{sub 2}O{sub 3} membrane for enhanced water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guanlong; Chen, Shuo, E-mail: shuochen@dlut.edu.cn; Yu, Hongtao; Quan, Xie

    2015-12-15

    Highlights: • Membrane filtration was integrated with photoelectrocatalysis for water treatment. • This integrated process (PECM) displays good antifouling capacity in NOMs removal. • PECM process enables efficient removal of chemical contaminants (e.g., RhB). • Enhanced charge separation of PECM process leads to its improved performance. - Abstract: Coupling membrane filtration with photocatalysis provides multifunction involving filtration and photocatalytic degradation for removing pollutants from water, but the performance of photocatalytic membrane is limited due to the quick recombination of photogenerated electron-holes in photocatalytic layer. Herein, a TiO{sub 2}/carbon/Al{sub 2}O{sub 3} membrane was designed and constructed through sequentially depositing graphitic carbon layer with good electro-conductivity and TiO{sub 2} nanoparticles layer with photocatalytic activity on Al{sub 2}O{sub 3} membrane support. When light irradiated on the membrane with a voltage supply, the photogenerated electrons could be drained from photocatalytic layer and separated with holes efficiently, thus endowing the membrane with photoelectrocatalytic function. Membrane performance tests indicated that the photoelectrocatalytic membrane filtration (PECM) showed improved removal of natural organic matters (NOMs) and permeate flux with increasing voltage supply. For PECM process at 1.0 V, its NOMs removal was 1.2 or 1.7 times higher than that of filtration with UV irradiation or filtration alone, and its stable permeate flux was 1.3 or 3 times higher than that of filtration with UV irradiation or filtration alone. Moreover, the PECM process exhibited special advantage in removing organic chemicals (e.g., Rhodamine B), which displayed 1.3 or 3 times higher removal than that of filtration with UV irradiation or filtration alone.

  10. RETINA EXPANSION TECHNIQUE FOR MACULAR HOLE APPOSITION REPORT 2: Efficacy, Closure Rate, and Risks of a Macular Detachment Technique to Close Large Full-Thickness Macular Holes.

    Science.gov (United States)

    Wong, Roger; Howard, Catherine; Orobona, Giancarlo Dellʼaversana

    2018-04-01

    To describe the safety and efficacy of a technique to close large thickness macular holes. A consecutive retrospective interventional case series of 16 patients with macular holes greater than 650 microns in "aperture" diameter were included. The technique involves vitrectomy, followed by internal limiting membrane peeling. The macula is detached using subretinal injection of saline. Fluid-air exchange is performed to promote detachment and stretch of the retina. After this, the standard fluid-air exchange is performed and perfluoropropane gas is injected. Face-down posturing is advised. Adverse effects, preoperative, and postoperative visual acuities were recorded. Optical coherence tomography scans were also taken. The mean hole size was 739 microns (SD: 62 microns; mean base diameter: 1,311 microns). Eighty-three percent (14 of 16) of eyes had successful hole closure after the procedure. At 12-month follow-up, no worsening in visual acuity was reported, and improvement in visual acuity was noted in 14 of 16 eyes. No patients lost vision because of the procedure. It is possible to achieve anatomical closure of large macular holes using RETMA. No patients experienced visual loss. The level of visual improvement is likely limited because of the size and chronicity of these holes.

  11. Searching for Primordial Black Holes in the Radio and X-Ray Sky.

    Science.gov (United States)

    Gaggero, Daniele; Bertone, Gianfranco; Calore, Francesca; Connors, Riley M T; Lovell, Mark; Markoff, Sera; Storm, Emma

    2017-06-16

    We model the accretion of gas onto a population of massive primordial black holes in the Milky Way and compare the predicted radio and x-ray emission with observational data. We show that, under conservative assumptions on the accretion process, the possibility that O(10)M_{⊙} primordial black holes can account for all of the dark matter in the Milky Way is excluded at 5σ by a comparison with a Very Large Array radio catalog at 1.4 GHz and at ≃40σ by a comparison with a Chandra x-ray catalog (0.5-8 keV). We argue that this method can be used to identify such a population of primordial black holes with more sensitive future radio and x-ray surveys.

  12. Long-range magnetostatic interactions in arrays of nanowires

    CERN Document Server

    Raposo, V; González, J M; Vázquez, M

    2000-01-01

    Experimental measurements and micromagnetic simulations of the hysteresis loops of arrays of cobalt nanowires are compared here. Arrays of cobalt nanowires (200 nm in diameter) were electrodeposited into the pores of alumina membranes (thickness 60 mu m). Their hysteresis loops along the axial direction of nanowires were measured using vibrating sample magnetometry. Micromagnetic simulations were performed considering dipolar interaction between nanowires leading to similar hysteresis loops as those obtained experimentally.

  13. A membrane paradigm at large D

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, Sayantani [Department of Physics, Indian Institute of Technology Kanpur,Kanpur 208016 (India); De, Anandita [Department of Physics, Indian Institute of Science Education and Research,Dr. Homi Bhabha Road, Pune 411008 (India); Minwalla, Shiraz; Mohan, Ravi; Saha, Arunabha [Department of Theoretical Physics, Tata Institute of Fundamental Research,Homi Bhabha Road, Mumbai 400005 (India)

    2016-04-13

    We study SO(d+1) invariant solutions of the classical vacuum Einstein equations in p+d+3 dimensions. In the limit d→∞ with p held fixed we construct a class of solutions labelled by the shape of a membrane (the event horizon), together with a ‘velocity’ field that lives on this membrane. We demonstrate that our metrics can be corrected to nonsingular solutions at first sub-leading order in (1/d) if and only if the membrane shape and ‘velocity’ field obey equations of motion which we determine. These equations define a well posed initial value problem for the membrane shape and this ‘velocity’ and so completely determine the dynamics of the black hole. They may be viewed as governing the non-linear dynamics of the light quasi normal modes of Emparan, Suzuki and Tanabe.

  14. Interaction of Dendritic Polymers with Synthetic Lipid and Cell Membranes

    Science.gov (United States)

    Mecke, Almut; Hong, Seungpyo; Bielinska, Anna U.; Banaszak Holl, Mark M.; Orr, Bradford G.; Baker, James R., Jr.

    2004-03-01

    Polyamidoamine (PAMAM) dendrimers are promising candidates for the development of nanoscale therapeutic transport agents. Here we present studies on dendrimer-membrane interactions leading to a better understanding of possible uptake mechanisms into cells. Using synthetic lipid and natural cell membranes as model systems it is shown that the effect of PAMAM dendrimers on a membrane strongly depends on the dendrimer generation, architecture and chemical properties of the branch end groups. Atomic force microscopy data indicates that generation 7 dendrimers have the ability to form small ( 10-100 nm) holes in a lipid bilayer. When dendrimers with otherwise identical chemical properties are arranged in a covalently linked cluster, no hole formation occurs. Dendrimer-lipid micelle formation is proposed and investigated as a possible mechanism for this behavior. Smaller dendrimers (generation 5) have a greatly reduced ability to remove lipid molecules from a bilayer. In addition to the size of the dendrimer, the charge of the branch end groups plays a significant role for dendrimer-membrane interactions. These results agree well with biological studies using cultured cells and point to a new mechanism of specific targeting and uptake into cells.

  15. Cantilever arrayed blood pressure sensor for arterial applanation tonometry.

    Science.gov (United States)

    Lee, Byeungleul; Jeong, Jinwoo; Kim, Jinseok; Kim, Bonghwan; Chun, Kukjin

    2014-03-01

    The authors developed a cantilever-arrayed blood pressure sensor array fabricated by (111) silicon bulk-micromachining for the non-invasive and continuous measurement of blood pressure. The blood pressure sensor measures the blood pressure based on the change in the resistance of the piezoresistor on a 5-microm-thick-arrayed perforated membrane and 20-microm-thick metal pads. The length and the width of the unit membrane are 210 and 310 microm, respectively. The width of the insensible zone between the adjacent units is only 10 microm. The resistance change over contact force was measured to verify the performance. The good linearity of the result confirmed that the polydimethylsiloxane package transfers the forces appropriately. The measured sensitivity was about 4.5%/N. The maximum measurement range and the resolution of the fabricated blood pressure sensor were greater than 900 mmHg (= 120 kPa) and less than 1 mmHg (= 133.3 Pa), respectively.

  16. The phase structure of higher-dimensional black rings and black holes

    International Nuclear Information System (INIS)

    Emparan, Roberto; Harmark, Troels; Niarchos, Vasilis; Obers, Niels A.; RodrIguez, Maria J.

    2007-01-01

    We construct an approximate solution for an asymptotically flat, neutral, thin rotating black ring in any dimension D ≥ 5 by matching the near-horizon solution for a bent boosted black string, to a linearized gravity solution away from the horizon. The rotating black ring solution has a regular horizon of topology S 1 x S D-3 and incorporates the balancing condition of the ring as a zero-tension condition. For D = 5 our method reproduces the thin ring limit of the exact black ring solution. For D ≥ 6 we show that the black ring has a higher entropy than the Myers-Perry black hole in the ultra-spinning regime. By exploiting the correspondence between ultra-spinning black holes and black membranes on a two-torus, we take steps towards qualitatively completing the phase diagram of rotating blackfolds with a single angular momentum. We are led to propose a connection between MP black holes and black rings, and between MP black holes and black Saturns, through merger transitions involving two kinds of 'pinched' black holes. More generally, the analogy suggests an infinite number of pinched black holes of spherical topology leading to a complicated pattern of connections and mergers between phases

  17. Integrated high-efficiency Pt/carbon nanotube arrays for PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weimin; Minett, Andrew I.; Zhao, Jie; Razal, Joselito M.; Wallace, Gordon G.; Romeo, Tony; Chen, Jun [Intelligent Polymer Research Institute, AIIM Facility, Innovation Campus, University of Wollongong, NSW 2522 (Australia); Gao, Mei [Division of Materials Science and Engineering, CSIRO, Bayview Ave, Clayton, VIC 3168 (Australia)

    2011-07-15

    A facile strategy to deposit Pt nanoparticles with various metal-loading densities on vertically aligned carbon nanotube (ACNT) arrays as electrocatalysts for proton exchange membrane (PEM) fuel cells is described. The deposition is achieved by electrostatic adsorption of the Pt precursor on the positively charged polyelectrolyte functionalized ACNT arrays and subsequent reduction by L-ascorbic acid. The application of the aligned electrocatalysts in fuel cells is realized by transferring from a quartz substrate to nafion membrane using a hot-press procedure to fabricate the membrane electrode assembly (MEA). It is shown that the MEA with vertically aligned structured electrocatalysts provides better Pt utilization than that with Pt on conventional carbon nanotubes or carbon black, resulting in higher fuel cell performance. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. NuSTARand Swift observations of the very high state in GX 339-4: Weighing the black hole with X-rays

    DEFF Research Database (Denmark)

    Parker, M. L.; Tomsick, J. A.; Kennea, J. A.

    2016-01-01

    We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0.95(-0.08)(+0.02) and ......We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0...

  19. Holey carbon micro-arrays for transmission electron microscopy: A microcontact printing approach

    International Nuclear Information System (INIS)

    Chester, David W.; Klemic, James F.; Stern, Eric; Sigworth, Fred J.; Klemic, Kathryn G.

    2007-01-01

    We have used a microcontact printing approach to produce high quality and inexpensive holey carbon micro-arrays. Fabrication involves: (1) micromolding a poly(dimethylsiloxane) (PDMS) elastomer stamp from a microfabricated master that contains the desired array pattern; (2) using the PDMS stamp for microcontact printing a thin sacrificial plastic film that contains an array of holes; (3) floating the plastic film onto TEM grids; (4) evaporating carbon onto the plastic film and (5) removing the sacrificial plastic film. The final holey carbon micro-arrays are ready for use as support films in TEM applications with the fidelity of the original microfabricated pattern. This approach is cost effective as both the master and the stamps have long-term reusability. Arbitrary array patterns can be made with microfabricated masters made through a single-step photolithographic process

  20. A small-animal imaging system capable of multipinhole circular/helical SPECT and parallel-hole SPECT

    International Nuclear Information System (INIS)

    Qian Jianguo; Bradley, Eric L.; Majewski, Stan; Popov, Vladimir; Saha, Margaret S.; Smith, Mark F.; Weisenberger, Andrew G.; Welsh, Robert E.

    2008-01-01

    We have designed and built a small-animal single-photon emission computed tomography (SPECT) imaging system equipped with parallel-hole and multipinhole collimators and capable of circular or helical SPECT. Copper-beryllium parallel-hole collimators suitable for imaging the ∼35 keV photons from the decay of 125 I have been built and installed to achieve useful spatial resolution over a range of object-detector distances and to reduce imaging time on our dual-detector array. To address the resolution limitations in the parallel-hole SPECT and the sensitivity and limited field of view of single-pinhole SPECT, we have incorporated multipinhole circular and helical SPECT in addition to expanding the parallel-hole SPECT capabilities. The pinhole SPECT system is based on a 110 mm diameter circular detector equipped with a pixellated NaI(Tl) scintillator array (1x1x5 mm 3 /pixel). The helical trajectory is accomplished by two stepping motors controlling the rotation of the detector-support gantry and displacement of the animal bed along the axis of rotation of the gantry. Results obtained in SPECT studies of various phantoms show an enlarged field of view, very good resolution and improved sensitivity using multipinhole circular or helical SPECT. Collimators with one, three and five, 1-mm-diameter pinholes have been implemented and compared in these tests. Our objective is to develop a system on which one may readily select a suitable mode of either parallel-hole SPECT or pinhole circular or helical SPECT for a variety of small animal imaging applications

  1. Laser cut hole matrices in novel armour plate steel for appliqué battlefield vehicle protection

    OpenAIRE

    Thomas, Daniel J.

    2016-01-01

    During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means of engineering lightweight armour. It was determined that a laser cutting speed of 1200 mm/min produced optimum hole formations with limited distortion. The array of holes acts as a double-edged solution, in that they provide weight saving of 45%, providing a protective advantage and i...

  2. Synthesis of ordered large-scale ZnO nanopore arrays

    International Nuclear Information System (INIS)

    Ding, G.Q.; Shen, W.Z.; Zheng, M.J.; Fan, D.H.

    2006-01-01

    An effective approach is demonstrated for growing ordered large-scale ZnO nanopore arrays through radio-frequency magnetron sputtering deposition on porous alumina membranes (PAMs). The realization of highly ordered hexagonal ZnO nanopore arrays benefits from the unique properties of ZnO (hexagonal structure, polar surfaces, and preferable growth directions) and PAMs (controllable hexagonal nanopores and localized negative charges). Further evidence has been shown through the effects of nanorod size and thermal treatment of PAMs on the yielded morphology of ZnO nanopore arrays. This approach opens the possibility of creating regular semiconducting nanopore arrays for the application of filters, sensors, and templates

  3. SWNT array resonant gate MOS transistor

    Energy Technology Data Exchange (ETDEWEB)

    Arun, A; Salet, P; Ionescu, A M [NanoLab, Ecole Polytechnique Federale de Lausanne, CH-1015, Lausanne (Switzerland); Campidelli, S; Filoramo, A; Derycke, V; Goffman, M F, E-mail: marcelo.goffman@cea.fr [Laboratoire d' Electronique Moleculaire, SPEC (CNRS URA 2454), IRAMIS, CEA, Gif-sur-Yvette (France)

    2011-02-04

    We show that thin horizontal arrays of single wall carbon nanotubes (SWNTs) suspended above the channel of silicon MOSFETs can be used as vibrating gate electrodes. This new class of nano-electromechanical system (NEMS) combines the unique mechanical and electronic properties of SWNTs with an integrated silicon-based motion detection. Its electrical response exhibits a clear signature of the mechanical resonance of SWNT arrays (120-150 MHz) showing that these thin horizontal arrays behave as a cohesive, rigid and elastic body membrane with a Young's modulus in the order of 1-10 GPa and ultra-low mass. The resonant frequency can be tuned by the gate voltage and its dependence is well understood within the continuum mechanics framework.

  4. Magnetic stripes and holes: Complex domain patterns in perforated films with weak perpendicular anisotropy

    Directory of Open Access Journals (Sweden)

    F. Valdés-Bango

    2017-05-01

    Full Text Available Hexagonal antidot arrays have been patterned on weak perpendicular magnetic anisotropy NdCo films by e-beam lithography and lift off. Domain structure has been characterized by Magnetic Force Microscopy at remanence. On a local length scale, of the order of stripe pattern period, domain configuration is controlled by edge effects within the stripe pattern: stripe domains meet the hole boundary at either perpendicular or parallel orientation. On a longer length scale, in-plane magnetostatic effects dominate the system: clear superdomains are observed in the patterned film with average in-plane magnetization along the easy directions of the antidot array, correlated over several antidot array cells.

  5. Magnetic stripes and holes: Complex domain patterns in perforated films with weak perpendicular anisotropy

    Science.gov (United States)

    Valdés-Bango, F.; Vélez, M.; Alvarez-Prado, L. M.; Alameda, J. M.; Martín, J. I.

    2017-05-01

    Hexagonal antidot arrays have been patterned on weak perpendicular magnetic anisotropy NdCo films by e-beam lithography and lift off. Domain structure has been characterized by Magnetic Force Microscopy at remanence. On a local length scale, of the order of stripe pattern period, domain configuration is controlled by edge effects within the stripe pattern: stripe domains meet the hole boundary at either perpendicular or parallel orientation. On a longer length scale, in-plane magnetostatic effects dominate the system: clear superdomains are observed in the patterned film with average in-plane magnetization along the easy directions of the antidot array, correlated over several antidot array cells.

  6. Anatomical and Functional Results of Lamellar Macular Holes Surgery.

    Science.gov (United States)

    Papadopoulou, D; Donati, G; Mangioris, G; Pournaras, C J

    2016-04-01

    To determine the long-term surgical findings and outcomes after vitrectomy for symptomatic lamellar macular holes. We studied 28 patients with lamellar macular holes and central visual loss or distortion. All interventions were standard 25 G vitrectomy with membranectomy of the internal limiting membrane (ILM), peeling and gas tamponade with SF6 20 %. Operations were performed by a single experienced surgeon within the last 3 years. Best corrected visual acuity and optical coherence tomography appearance were determined preoperatively and postoperatively. Following the surgical procedure, all macular holes were closed; however, in 3 eyes, significant foveal thinning was associated with changes in the retinal pigment epithelium changes. The mean best-corrected visual acuity improved postoperatively in the majority of the patients (n: 21, mean 0.3 logMAR), stabilised in 4 patients and decreased in 3 patients (mean 0.4 logMAR). Spectral Domain-Optical coherence tomography (SD-OCT) showed resolution of the lamellar lesion and improved macular contour in all cases. We demonstrated improvement in postoperative vision and the anatomical reconstruction of the anatomical contour of the fovea in most eyes with symptomatic lamellar holes. These findings indicate that vitrectomy, membranectomy and ILM peeling with gas tamponade is a beneficial treatment of symptomatic lamellar macular holes. Georg Thieme Verlag KG Stuttgart · New York.

  7. Two Dimensional Array of Piezoresistive Nanomechanical Membrane-Type Surface Stress Sensor (MSS with Improved Sensitivity

    Directory of Open Access Journals (Sweden)

    Nico F. de Rooij

    2012-11-01

    Full Text Available We present a new generation of piezoresistive nanomechanical Membrane-type Surface stress Sensor (MSS chips, which consist of a two dimensional array of MSS on a single chip. The implementation of several optimization techniques in the design and microfabrication improved the piezoresistive sensitivity by 3~4 times compared to the first generation MSS chip, resulting in a sensitivity about ~100 times better than a standard cantilever-type sensor and a few times better than optical read-out methods in terms of experimental signal-to-noise ratio. Since the integrated piezoresistive read-out of the MSS can meet practical requirements, such as compactness and not requiring bulky and expensive peripheral devices, the MSS is a promising transducer for nanomechanical sensing in the rapidly growing application fields in medicine, biology, security, and the environment. Specifically, its system compactness due to the integrated piezoresistive sensing makes the MSS concept attractive for the instruments used in mobile applications. In addition, the MSS can operate in opaque liquids, such as blood, where optical read-out techniques cannot be applied.

  8. Saturated multikilovolt x-ray amplification with Xe clusters: single-pulse observation of Xe(L) spectral hole burning

    International Nuclear Information System (INIS)

    Borisov, Alex B; Davis, Jack; Song, Xiangyang; Koshman, Yevgeniya; Dai Yang; Boyer, Keith; Rhodes, Charles K

    2003-01-01

    Single-pulse measurements of spectral hole burning of Xe(L) 3d → 2p hollow atom transition arrays observed from a self-trapped plasma channel provide new information on the dynamics of saturated amplification in the λ ∼ 2.8-2.9 A region. The spectral hole burning on transitions in the Xe 34+ and Xe 35+ arrays reaches full suppression of the spontaneous emission and presents a corresponding width Δ h-bar ω x ∼ = 60 eV, a value adequate for efficient amplification of multikilovolt x-ray pulses down to a limiting length τ x ∼ 30 as. The depth of the suppression at 2.86 A indicates that the gain-to-loss ratio is ≥10. An independent determination of the x-ray pulse energy from damage produced on the surface of a Ti foil in the far field of the source gives a pulse energy of 20-30 μJ, a range that correlates well with the observation of the spectral hole burning and indicates an overall extraction efficiency of ∼10%. (letter to the editor)

  9. Refractive changes after vitrectomy and phacovitrectomy for macular hole and epiretinal membrane

    DEFF Research Database (Denmark)

    Hamoudi, Hassan; La Cour, Morten

    2013-01-01

    a role in refraction, including measurement of the axial length, changes in the effective lens position and the anterior chamber depth, the use of intraocular gas tamponade, the formula for intraocular lens (IOL) power calculation, and the IOL type. Most phakic eyes with macular hole or epiretinal...

  10. Anodic aluminium oxide membranes used for the growth of carbon nanotubes.

    Science.gov (United States)

    López, Vicente; Morant, Carmen; Márquez, Francisco; Zamora, Félix; Elizalde, Eduardo

    2009-11-01

    The suitability of anodic aluminum oxide (AAO) membranes as template supported on Si substrates for obtaining organized iron catalyst for carbon nanotube (CNT) growth has been investigated. The iron catalyst was confined in the holes of the AAO membrane. CVD synthesis with ethylene as carbon source led to a variety of carbon structures (nanotubes, helices, bamboo-like, etc). In absence of AAO membrane the catalyst was homogeneously distributed on the Si surface producing a high density of micron-length CNTs.

  11. ParaSol - A Novel Deployable Approach for Very Large Ultra-lightweight Solar Arrays, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — High power solar arrays with capabilities of >100kW are needed for projected NASA missions. Photovoltaic arrays using deployable membranes with thin cells have...

  12. Single night postoperative prone posturing in idiopathic macular hole surgery.

    LENUS (Irish Health Repository)

    2012-02-01

    Purpose. To evaluate the role of postoperative prone posturing for a single night in the outcome of trans pars plana vitrectomy (TPPV) with internal limiting membrane (ILM) peel and 20% perfluoroethane (C2F6) internal tamponade for idiopathic macular hole. Methods. This prospective trial enrolled 14 eyes in 14 consecutive patients with idiopathic macular hole. All eyes underwent TPPV with vision blue assisted ILM peeling with and without phacoemulsification and intraocular lens (IOL) for macular hole. Intraocular gas tamponade (20% C2F6) was used in all cases with postoperative face-down posturing overnight and without specific posturing afterwards. LogMAR visual acuity, appearance by slit-lamp biomicroscopy, and ocular coherence tomography (OCT) scans were compared preoperatively and postoperatively to assess outcome. Results. Among 14 eyes recruited, all eyes were phakic; 50% of patients underwent concurrent phacoemulsification with IOL. The macular holes were categorized preoperatively by OCT appearance, 4 (28.57%) were stage 2, 7 (50%) were stage 3, and 3 (21.43%) were stage 4. Mean macular hole size was 0.35 disk diameters. Symptoms of macular hole had been present for an average of 6.5 months. All holes (100%) were closed 3 and 6 months postoperatively. Mean visual acuity (logMAR) was improved to 0.61 at 3 months and was stable at 6 months after the surgery. None of the eyes had worse vision postoperatively. Conclusions. Vitrectomy with ILM peeling and 20% C2F6 gas with a brief postoperative 1 night prone posturing regimen is a reasonable approach to achieve anatomic closure in idiopathic macular hole. Concurrent cataract extraction did not alter outcomes and was not associated with any additional complications.

  13. Exercises in anatomy: holes between the ventricles.

    Science.gov (United States)

    Anderson, Robert H; Sarwark, Anne E; Spicer, Diane E; Backer, Carl L

    2014-01-01

    Holes between the ventricles are the commonest congenital cardiac malformations. As yet, however, there is no consensus as to how they can best be described and categorized. In this, our third exercise in cardiac anatomy, we address the issue of classification of ventricular septal defects. We begin our demonstration by analysing the normal heart. We show that the larger part of the ventricular septum is made up of its muscular component. The membranous part accounts for only a small portion, which is located centrally within the cardiac base. This small membranous part forms a boundary between the right-sided chambers and the aortic root. Holes at this site, therefore, which account for the commonest defects closed surgically, will open centrally in the cardiac base, being located postero-inferiorly relative to the supraventricular crest. We then show that the larger part of the crest itself is a free-standing muscular sleeve, which lifts the leaflets of the pulmonary valve away from the cardiac base. Only a very small part of the muscle forming the right ventricular outlet is located in the septal position. Turning our attention to malformed hearts, we show how holes between the ventricles can open centrally at the cardiac base, open to the inlet or outlet of the right ventricle or open within the substance of the apical muscular septum. We demonstrate, however, that description of such geographical location of the defects does not paint the full picture, since lesions with markedly different phenotypic features can open in comparable geographic locations. We illustrate how it is the phenotypic features, as seen from the right ventricle, which convey the crucial information for the surgeon with regard to the location of the atrioventricular conduction axis, using hearts with holes opening to the inlet of the right ventricle with muscular as opposed to partially fibrous borders to emphasize this point. We continue by showing how holes with different phenotypes can

  14. Domains of increased thickness in microvillar membranes of the small intestinal enterocyte

    DEFF Research Database (Denmark)

    Kunding, Andreas H; Christensen, Sune M; Danielsen, E Michael

    2010-01-01

    The apical surface of the enterocyte is sculpted into a dense array of cylindrical microvillar protrusions by supporting actin filaments. Membrane microdomains (rafts) enriched in cholesterol and glycosphingolipids comprise roughly 50% of the microvillar membrane and play a vital role in orchestr......The apical surface of the enterocyte is sculpted into a dense array of cylindrical microvillar protrusions by supporting actin filaments. Membrane microdomains (rafts) enriched in cholesterol and glycosphingolipids comprise roughly 50% of the microvillar membrane and play a vital role...... in orchestrating absorptive/digestive action of dietary nutrients at this important cellular interface. Increased membrane thickness is believed to be a morphological characteristic of rafts. Thus, we investigated whether the high contents of lipid rafts in the microvillar membrane is reflected in local variations...... was clearly monophasic. The encountered domains of increased thickness (DITs) occupied 48% of the microvillar membrane and from the data we estimated the area of a single DIT to have a lower limit of 600 nm(2). In other experiments we mapped the organization of biochemically defined lipid rafts by immunogold...

  15. No tension between assembly models of super massive black hole binaries and pulsar observations.

    Science.gov (United States)

    Middleton, Hannah; Chen, Siyuan; Del Pozzo, Walter; Sesana, Alberto; Vecchio, Alberto

    2018-02-08

    Pulsar timing arrays are presently the only means to search for the gravitational wave stochastic background from super massive black hole binary populations, considered to be within the grasp of current or near-future observations. The stringent upper limit from the Parkes Pulsar Timing Array has been interpreted as excluding (>90% confidence) the current paradigm of binary assembly through galaxy mergers and hardening via stellar interaction, suggesting evolution is accelerated or stalled. Using Bayesian hierarchical modelling we consider implications of this upper limit for a range of astrophysical scenarios, without invoking stalling, nor more exotic physical processes. All scenarios are fully consistent with the upper limit, but (weak) bounds on population parameters can be inferred. Recent upward revisions of the black hole-galaxy bulge mass relation are disfavoured at 1.6σ against lighter models. Once sensitivity improves by an order of magnitude, a non-detection will disfavour the most optimistic scenarios at 3.9σ.

  16. Depth dependence of Neel wall pinning on amorphous Co x Si1-x films with diluted arrays of elliptical antidots

    International Nuclear Information System (INIS)

    Perez-Junquera, A.; Martin, J.I.; Anguita, J.V.; Rodriguez-Rodriguez, G.; Velez, M.; Rubio, H.; Alvarez-Prado, L.M.; Alameda, J.M.

    2007-01-01

    Diluted arrays of elliptical antidots have been fabricated by optical lithography, electron beam lithography and plasma etching on amorphous Co 74 Si 26 magnetic films with a well-defined uniaxial anisotropy. The magnetic behavior of two identical antidot arrays but with different hole depth in comparison with film thickness has been studied by transverse magneto-optical Kerr effect. Significant differences appear in the coercivity depending on whether the magnetic film is completely perforated or not, indicating a much more effective domain wall pinning process when the depth of the holes is smaller than the magnetic film thickness

  17. Black holes

    International Nuclear Information System (INIS)

    Feast, M.W.

    1981-01-01

    This article deals with two questions, namely whether it is possible for black holes to exist, and if the answer is yes, whether we have found any yet. In deciding whether black holes can exist or not the central role in the shaping of our universe played by the forse of gravity is discussed, and in deciding whether we are likely to find black holes in the universe the author looks at the way stars evolve, as well as white dwarfs and neutron stars. He also discusses the problem how to detect a black hole, possible black holes, a southern black hole, massive black holes, as well as why black holes are studied

  18. Surprise: Dwarf Galaxy Harbors Supermassive Black Hole

    Science.gov (United States)

    2011-01-01

    The surprising discovery of a supermassive black hole in a small nearby galaxy has given astronomers a tantalizing look at how black holes and galaxies may have grown in the early history of the Universe. Finding a black hole a million times more massive than the Sun in a star-forming dwarf galaxy is a strong indication that supermassive black holes formed before the buildup of galaxies, the astronomers said. The galaxy, called Henize 2-10, 30 million light-years from Earth, has been studied for years, and is forming stars very rapidly. Irregularly shaped and about 3,000 light-years across (compared to 100,000 for our own Milky Way), it resembles what scientists think were some of the first galaxies to form in the early Universe. "This galaxy gives us important clues about a very early phase of galaxy evolution that has not been observed before," said Amy Reines, a Ph.D. candidate at the University of Virginia. Supermassive black holes lie at the cores of all "full-sized" galaxies. In the nearby Universe, there is a direct relationship -- a constant ratio -- between the masses of the black holes and that of the central "bulges" of the galaxies, leading them to conclude that the black holes and bulges affected each others' growth. Two years ago, an international team of astronomers found that black holes in young galaxies in the early Universe were more massive than this ratio would indicate. This, they said, was strong evidence that black holes developed before their surrounding galaxies. "Now, we have found a dwarf galaxy with no bulge at all, yet it has a supermassive black hole. This greatly strengthens the case for the black holes developing first, before the galaxy's bulge is formed," Reines said. Reines, along with Gregory Sivakoff and Kelsey Johnson of the University of Virginia and the National Radio Astronomy Observatory (NRAO), and Crystal Brogan of the NRAO, observed Henize 2-10 with the National Science Foundation's Very Large Array radio telescope and

  19. Photovoltaic devices based on quantum dot functionalized nanowire arrays embedded in an organic matrix

    Science.gov (United States)

    Kung, Patrick; Harris, Nicholas; Shen, Gang; Wilbert, David S.; Baughman, William; Balci, Soner; Dawahre, Nabil; Butler, Lee; Rivera, Elmer; Nikles, David; Kim, Seongsin M.

    2012-01-01

    Quantum dot (QD) functionalized nanowire arrays are attractive structures for low cost high efficiency solar cells. QDs have the potential for higher quantum efficiency, increased stability and lifetime compared to traditional dyes, as well as the potential for multiple electron generation per photon. Nanowire array scaffolds constitute efficient, low resistance electron transport pathways which minimize the hopping mechanism in the charge transport process of quantum dot solar cells. However, the use of liquid electrolytes as a hole transport medium within such scaffold device structures have led to significant degradation of the QDs. In this work, we first present the synthesis uniform single crystalline ZnO nanowire arrays and their functionalization with InP/ZnS core-shell quantum dots. The structures are characterized using electron microscopy, optical absorption, photoluminescence and Raman spectroscopy. Complementing photoluminescence, transmission electron microanalysis is used to reveal the successful QD attachment process and the atomistic interface between the ZnO and the QD. Energy dispersive spectroscopy reveals the co-localized presence of indium, phosphorus, and sulphur, suggestive of the core-shell nature of the QDs. The functionalized nanowire arrays are subsequently embedded in a poly-3(hexylthiophene) hole transport matrix with a high degree of polymer infiltration to complete the device structure prior to measurement.

  20. Integrated strain array for cellular mechanobiology studies

    International Nuclear Information System (INIS)

    Simmons, C S; Sim, J Y; Baechtold, P; Chung, C; Borghi, N; Pruitt, B L; Gonzalez, A

    2011-01-01

    We have developed an integrated strain array for cell culture enabling high-throughput mechano-transduction studies. Biocompatible cell culture chambers were integrated with an acrylic pneumatic compartment and microprocessor-based control system. Each element of the array consists of a deformable membrane supported by a cylindrical pillar within a well. For user-prescribed waveforms, the annular region of the deformable membrane is pulled into the well around the pillar under vacuum, causing the pillar-supported region with cultured cells to be stretched biaxially. The optically clear device and pillar-based mechanism of operation enables imaging on standard laboratory microscopes. Straightforward fabrication utilizes off-the-shelf components, soft lithography techniques in polydimethylsiloxane and laser ablation of acrylic sheets. Proof of compatibility with basic biological assays and standard imaging equipment were accomplished by straining C2C12 skeletal myoblasts on the device for 6 h. At higher strains, cells and actin stress fibers realign with a circumferential preference

  1. σ-holes and π-holes: Similarities and differences.

    Science.gov (United States)

    Politzer, Peter; Murray, Jane S

    2018-04-05

    σ-Holes and π-holes are regions of molecules with electronic densities lower than their surroundings. There are often positive electrostatic potentials associated with them. Through these potentials, the molecule can interact attractively with negative sites, such as lone pairs, π electrons, and anions. Such noncovalent interactions, "σ-hole bonding" and "π-hole bonding," are increasingly recognized as being important in a number of different areas. In this article, we discuss and compare the natures and characteristics of σ-holes and π-holes, and factors that influence the strengths and locations of the resulting electrostatic potentials. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  2. Micro-ring structures stabilize microdroplets to enable long term spheroid culture in 384 hanging drop array plates.

    Science.gov (United States)

    Hsiao, Amy Y; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J; Takayama, Shuichi

    2012-04-01

    Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis.

  3. Development of an Automation Technique for the Establishment of Functional Lipid Bilayer Arrays

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard; Perry, Mark; Vogel, Jörg

    2009-01-01

    In the present work, a technique for establishing multiple black lipid membranes (BLMs) in arrays of micro structured ethylene tetrafluoroethylene (ETFE) films, and supported by a micro porous material was developed. Rectangular 8 x 8 arrays with apertures having diameters of 301 +/- 5 mu m were...

  4. Separation of tritiated water from water using composite membranes

    International Nuclear Information System (INIS)

    Duncan, J.; Nelson, D.

    1996-01-01

    Polymeric composite membranes are being developed to remove tritium from contaminated water at DOE sites. Industrial membrane systems are being developed that have proven to be energy efficient, and membrane technologies such as reverse-osmosis have been well developed for desalination and other industrial/municipal applications. Aromatic polyphosphazene membranes are being investigated because they have excellent radiological, thermal, and chemical stability. The FY 1996 effort is directed toward delineating a potential mechanism, providing a statistical approach to data acquisition, refining a mass balance, and designing a staged array module

  5. A Novel Self-aligned and Maskless Process for Formation of Highly Uniform Arrays of Nanoholes and Nanopillars

    Directory of Open Access Journals (Sweden)

    Wu Wei

    2008-01-01

    Full Text Available AbstractFabrication of a large area of periodic structures with deep sub-wavelength features is required in many applications such as solar cells, photonic crystals, and artificial kidneys. We present a low-cost and high-throughput process for realization of 2D arrays of deep sub-wavelength features using a self-assembled monolayer of hexagonally close packed (HCP silica and polystyrene microspheres. This method utilizes the microspheres as super-lenses to fabricate nanohole and pillar arrays over large areas on conventional positive and negative photoresist, and with a high aspect ratio. The period and diameter of the holes and pillars formed with this technique can be controlled precisely and independently. We demonstrate that the method can produce HCP arrays of hole of sub-250 nm size using a conventional photolithography system with a broadband UV source centered at 400 nm. We also present our 3D FDTD modeling, which shows a good agreement with the experimental results.

  6. Superresolving Black Hole Images with Full-Closure Sparse Modeling

    Science.gov (United States)

    Crowley, Chelsea; Akiyama, Kazunori; Fish, Vincent

    2018-01-01

    It is believed that almost all galaxies have black holes at their centers. Imaging a black hole is a primary objective to answer scientific questions relating to relativistic accretion and jet formation. The Event Horizon Telescope (EHT) is set to capture images of two nearby black holes, Sagittarius A* at the center of the Milky Way galaxy roughly 26,000 light years away and the other M87 which is in Virgo A, a large elliptical galaxy that is 50 million light years away. Sparse imaging techniques have shown great promise for reconstructing high-fidelity superresolved images of black holes from simulated data. Previous work has included the effects of atmospheric phase errors and thermal noise, but not systematic amplitude errors that arise due to miscalibration. We explore a full-closure imaging technique with sparse modeling that uses closure amplitudes and closure phases to improve the imaging process. This new technique can successfully handle data with systematic amplitude errors. Applying our technique to synthetic EHT data of M87, we find that full-closure sparse modeling can reconstruct images better than traditional methods and recover key structural information on the source, such as the shape and size of the predicted photon ring. These results suggest that our new approach will provide superior imaging performance for data from the EHT and other interferometric arrays.

  7. Comparison of Chemical Sensitivity of Fresh and Long-Stored Heat Resistant Neosartorya fischeri Environmental Isolates Using BIOLOG Phenotype MicroArray System.

    Directory of Open Access Journals (Sweden)

    Jacek Panek

    Full Text Available Spoilage of heat processed food and beverage by heat resistant fungi (HRF is a major problem for food industry in many countries. Neosartorya fischeri is the leading source of spoilage in thermally processed products. Its resistance to heat processing and toxigenicity makes studies about Neosartorya fischeri metabolism and chemical sensitivity essential. In this study chemical sensitivity of two environmental Neosartorya fischeri isolates were compared. One was isolated from canned apples in 1923 (DSM3700, the other from thermal processed strawberry product in 2012 (KC179765, used as long-stored and fresh isolate, respectively. The study was conducted using Biolog Phenotype MicroArray platforms of chemical sensitivity panel and traditional hole-plate method. The study allowed for obtaining data about Neosartorya fischeri growth inhibitors. The fresh isolate appeared to be much more resistant to chemical agents than the long-stored isolate. Based on phenotype microarray assay nitrogen compounds, toxic cations and membrane function compounds were the most effective in growth inhibition of N. fischeri isolates. According to the study zaragozic acid A, thallium(I acetate and sodium selenate were potent and promising N. fischeri oriented fungicides which was confirmed by both chemical sensitivity microplates panel and traditional hole-plate methods.

  8. Ultra-high-aspect-orthogonal and tunable three dimensional polymeric nanochannel stack array for BioMEMS applications

    Science.gov (United States)

    Heo, Joonseong; Kwon, Hyukjin J.; Jeon, Hyungkook; Kim, Bumjoo; Kim, Sung Jae; Lim, Geunbae

    2014-07-01

    Nanofabrication technologies have been a strong advocator for new scientific fundamentals that have never been described by traditional theory, and have played a seed role in ground-breaking nano-engineering applications. In this study, we fabricated ultra-high-aspect (~106 with O(100) nm nanochannel opening and O(100) mm length) orthogonal nanochannel array using only polymeric materials. Vertically aligned nanochannel arrays in parallel can be stacked to form a dense nano-structure. Due to the flexibility and stretchability of the material, one can tune the size and shape of the nanochannel using elongation and even roll the stack array to form a radial-uniformly distributed nanochannel array. The roll can be cut at discretionary lengths for incorporation with a micro/nanofluidic device. As examples, we demonstrated ion concentration polarization with the device for Ohmic-limiting/overlimiting current-voltage characteristics and preconcentrated charged species. The density of the nanochannel array was lower than conventional nanoporous membranes, such as anodic aluminum oxide membranes (AAO). However, accurate controllability over the nanochannel array dimensions enabled multiplexed one microstructure-on-one nanostructure interfacing for valuable biological/biomedical microelectromechanical system (BioMEMS) platforms, such as nano-electroporation.Nanofabrication technologies have been a strong advocator for new scientific fundamentals that have never been described by traditional theory, and have played a seed role in ground-breaking nano-engineering applications. In this study, we fabricated ultra-high-aspect (~106 with O(100) nm nanochannel opening and O(100) mm length) orthogonal nanochannel array using only polymeric materials. Vertically aligned nanochannel arrays in parallel can be stacked to form a dense nano-structure. Due to the flexibility and stretchability of the material, one can tune the size and shape of the nanochannel using elongation and even

  9. Value of internal limiting membrane peeling in surgery for idiopathic macular hole and the correlation between function and retinal morphology

    DEFF Research Database (Denmark)

    Christensen, Ulrik Correll

    2009-01-01

    conducted a randomized clinical trial including 78 pseudophakic patients with idiopathic macular hole stages 2 and 3. Patients were randomly assigned to macular hole surgery consisting of (i) vitrectomy alone without instrumental retinal surface contact (non-peeling), (ii) vitrectomy plus 0.05% isotonic ICG...... rate than surgery without ILM peeling (95% versus 45%). The overall functional results confirm that surgery for macular hole generally leads to favourable visual results, with two-thirds of eyes regaining reading vision (>or=20/40). Macular hole surgery can be considered a safe procedure with a low...... incidence of sight-threatening adverse events; the retinal detachment rate was 2.2%. Visual outcomes in eyes with primary hole closure were not significantly different between the intervention groups; however, for the stage 2 subgroup with primary macular hole closure, there was a trend towards a better...

  10. Anomalous transmission through heavily doped conducting polymer films with periodic subwavelength hole array

    Science.gov (United States)

    Matsui, Tatsunosuke; Vardeny, Z. Valy; Agrawal, Amit; Nahata, Ajay; Menon, Reghu

    2006-08-01

    We observed resonantly enhanced (or anomalous transmission) terahertz transmission through two-dimensional (2D) periodic arrays of subwavelength apertures with various periodicities fabricated on metallic organic conducting polymer films of polypyrrole heavily doped with PF 6 molecules [PPy(PF6)]. The anomalous transmission spectra are in good agreement with a model involving surface plasmon polariton excitations on the film surfaces. We also found that the resonantly enhanced transmission peaks are broader in the exotic metallic PPy(PF6) films compared to those formed in 2D aperture array in regular metallic films such as silver, indicating that the surface plasmon polaritons on the PPy(PF6) film surfaces have higher attenuation.

  11. The actin homologue MreB organizes the bacterial cell membrane

    OpenAIRE

    Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W.

    2014-01-01

    The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lip...

  12. Vitrectomy with internal limiting membrane (ILM) peeling versus vitrectomy with no peeling for idiopathic full-thickness macular hole (FTMH).

    Science.gov (United States)

    Spiteri Cornish, Kurt; Lois, Noemi; Scott, Neil; Burr, Jennifer; Cook, Jonathan; Boachie, Charles; Tadayoni, Ramin; la Cour, Morten; Christensen, Ulrik; Kwok, Alvin

    2013-06-05

    Several observational studies have suggested the potential benefit of internal limiting membrane (ILM) peeling to treat idiopathic full-thickness macular hole (FTMH). However, no strong evidence is available on the potential benefit(s) of this surgical manoeuvre and uncertainty remains among vitreoretinal surgeons about the indication for peeling the ILM, whether to use it in all cases or in long-standing and/or larger holes.  To determine whether ILM peeling improves anatomical and functional outcomes of macular hole surgery compared with the no-peeling technique and to investigate the impact of different parameters such as presenting vision, stage/size of the hole and duration of symptoms in the success of the surgery. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) which contains the Cochrane Eyes and Vision Group Trials Register (The Cochrane Library 2013, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to February 2013), EMBASE (January 1980 to February 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We searched the reference lists of included studies for any additional studies not identified by the electronic searches. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 February 2013.We searched reference lists of the studies included in the review for information about other studies on ILM peeling in macular hole surgery. We searched Proceedings for the following conferences up to February 2013: American Academy of Ophthalmology (AAO), Annual Meeting of the American Society of Retina Specialists

  13. Cryo-electron microscopy of membrane proteins.

    Science.gov (United States)

    Goldie, Kenneth N; Abeyrathne, Priyanka; Kebbel, Fabian; Chami, Mohamed; Ringler, Philippe; Stahlberg, Henning

    2014-01-01

    Electron crystallography is used to study membrane proteins in the form of planar, two-dimensional (2D) crystals, or other crystalline arrays such as tubular crystals. This method has been used to determine the atomic resolution structures of bacteriorhodopsin, tubulin, aquaporins, and several other membrane proteins. In addition, a large number of membrane protein structures were studied at a slightly lower resolution, whereby at least secondary structure motifs could be identified.In order to conserve the structural details of delicate crystalline arrays, cryo-electron microscopy (cryo-EM) allows imaging and/or electron diffraction of membrane proteins in their close-to-native state within a lipid bilayer membrane.To achieve ultimate high-resolution structural information of 2D crystals, meticulous sample preparation for electron crystallography is of outmost importance. Beam-induced specimen drift and lack of specimen flatness can severely affect the attainable resolution of images for tilted samples. Sample preparations that sandwich the 2D crystals between symmetrical carbon films reduce the beam-induced specimen drift, and the flatness of the preparations can be optimized by the choice of the grid material and the preparation protocol.Data collection in the cryo-electron microscope using either the imaging or the electron diffraction mode has to be performed applying low-dose procedures. Spot-scanning further reduces the effects of beam-induced drift. Data collection using automated acquisition schemes, along with improved and user-friendlier data processing software, is increasingly being used and is likely to bring the technique to a wider user base.

  14. Transdermal Delivery of siRNA through Microneedle Array

    Science.gov (United States)

    Deng, Yan; Chen, Jiao; Zhao, Yi; Yan, Xiaohui; Zhang, Li; Choy, Kwongwai; Hu, Jun; Sant, Himanshu J.; Gale, Bruce K.; Tang, Tao

    2016-02-01

    Successful development of siRNA therapies has significant potential for the treatment of skin conditions (alopecia, allergic skin diseases, hyperpigmentation, psoriasis, skin cancer, pachyonychia congenital) caused by aberrant gene expression. Although hypodermic needles can be used to effectively deliver siRNA through the stratum corneum, the major challenge is that this approach is painful and the effects are restricted to the injection site. Microneedle arrays may represent a better way to deliver siRNAs across the stratum corneum. In this study, we evaluated for the first time the ability of the solid silicon microneedle array for punching holes to deliver cholesterol-modified housekeeping gene (Gapdh) siRNA to the mouse ear skin. Treating the ear with microneedles showed permeation of siRNA in the skin and could reduce Gapdh gene expression up to 66% in the skin without accumulation in the major organs. The results showed that microneedle arrays could effectively deliver siRNA to relevant regions of the skin noninvasively.

  15. Fabrication of Phased Array EMAT and Its Characteristics

    International Nuclear Information System (INIS)

    Ahn, Bong Young; Cho, Seung Hyun; Kim, Young Joo; Kim, Ki Bok

    2010-01-01

    EMAT has been applied in various fields for flaw detection and material characterization because it has noncontact property in wave generation and a good mode selectivity. Unfortunately, however, EMAT shows low signal to noise ratio relative to commercial contact transducer because of low energy conversion efficiency. If the phase matching through the control of time delay between each coil consisting of the array EMAT is accomplished, it is expected that it will be a solution for the improvement of low signal to noise ratio. In this experiment, the phased array EMATs which consists of 3 or 4 meander coils and one big magnet were fabricated for surface and vertical shear wave generation. Effect of phased delay control on signal directivity and amplitude enhancement was verified. A slit with the depth of 0.5 mm and a side-drill hole of 0.5 mm diameter were clearly detected by fabricated phased array EMATs, respectively

  16. Black hole astrophysics

    International Nuclear Information System (INIS)

    Blandford, R.D.; Thorne, K.S.

    1979-01-01

    Following an introductory section, the subject is discussed under the headings: on the character of research in black hole astrophysics; isolated holes produced by collapse of normal stars; black holes in binary systems; black holes in globular clusters; black holes in quasars and active galactic nuclei; primordial black holes; concluding remarks on the present state of research in black hole astrophysics. (U.K.)

  17. A microelectromechanical system artificial basilar membrane based on a piezoelectric cantilever array and its characterization using an animal model

    Science.gov (United States)

    Jang, Jongmoon; Lee, Jangwoo; Woo, Seongyong; Sly, David J.; Campbell, Luke J.; Cho, Jin-Ho; O'Leary, Stephen J.; Park, Min-Hyun; Han, Sungmin; Choi, Ji-Wong; Hun Jang, Jeong; Choi, Hongsoo

    2015-07-01

    We proposed a piezoelectric artificial basilar membrane (ABM) composed of a microelectromechanical system cantilever array. The ABM mimics the tonotopy of the cochlea: frequency selectivity and mechanoelectric transduction. The fabricated ABM exhibits a clear tonotopy in an audible frequency range (2.92-12.6 kHz). Also, an animal model was used to verify the characteristics of the ABM as a front end for potential cochlear implant applications. For this, a signal processor was used to convert the piezoelectric output from the ABM to an electrical stimulus for auditory neurons. The electrical stimulus for auditory neurons was delivered through an implanted intra-cochlear electrode array. The amplitude of the electrical stimulus was modulated in the range of 0.15 to 3.5 V with incoming sound pressure levels (SPL) of 70.1 to 94.8 dB SPL. The electrical stimulus was used to elicit an electrically evoked auditory brainstem response (EABR) from deafened guinea pigs. EABRs were successfully measured and their magnitude increased upon application of acoustic stimuli from 75 to 95 dB SPL. The frequency selectivity of the ABM was estimated by measuring the magnitude of EABRs while applying sound pressure at the resonance and off-resonance frequencies of the corresponding cantilever of the selected channel. In this study, we demonstrated a novel piezoelectric ABM and verified its characteristics by measuring EABRs.

  18. Micro-array versus nano-array platforms: a comparative study for ODN detection based on SPR enhanced ellipsometry

    International Nuclear Information System (INIS)

    Celen, Burcu; Piskin, Erhan; Demirel, Goekhan

    2011-01-01

    The rapid and sensitive detection of DNA has recently attracted worldwide attention for a variety of disease diagnoses and detection of harmful bacteria in food and drink. In this paper, we carried out a comparative study based on surface plasmon resonance enhanced ellipsometry (SPREE) for the detection of oligodeoxynucleotides (ODNs) using micro- and nano-array platforms. The micro-arrayed surfaces were fabricated by a photolithography approach using different types of mask having varying size and shape. Well-ordered arrays of high aspect ratio polymeric nanotubes were also obtained using high molecular weight polystyrene (PS) and anodic aluminum oxide (AAO) membranes having 200 nm pore diameters. The SPREE sensors were then prepared by direct coupling of thiolated probe-ODNs, which contain suitable spacer arms, on gold-coated micro- and nano-arrayed surfaces. We experimentally demonstrated that, for the first time, gold-coated free standing polymeric nano-arrayed platforms can easily be produced and lead to a significant sensor sensitivity gain compared to that of the conventional SPREE surfaces of about four times. We believe that such an enhancement in sensor response could be useful for next generation sensor systems.

  19. Micro-array versus nano-array platforms: a comparative study for ODN detection based on SPR enhanced ellipsometry

    Science.gov (United States)

    Celen, Burcu; Demirel, Gökhan; Piskin, Erhan

    2011-04-01

    The rapid and sensitive detection of DNA has recently attracted worldwide attention for a variety of disease diagnoses and detection of harmful bacteria in food and drink. In this paper, we carried out a comparative study based on surface plasmon resonance enhanced ellipsometry (SPREE) for the detection of oligodeoxynucleotides (ODNs) using micro- and nano-array platforms. The micro-arrayed surfaces were fabricated by a photolithography approach using different types of mask having varying size and shape. Well-ordered arrays of high aspect ratio polymeric nanotubes were also obtained using high molecular weight polystyrene (PS) and anodic aluminum oxide (AAO) membranes having 200 nm pore diameters. The SPREE sensors were then prepared by direct coupling of thiolated probe-ODNs, which contain suitable spacer arms, on gold-coated micro- and nano-arrayed surfaces. We experimentally demonstrated that, for the first time, gold-coated free standing polymeric nano-arrayed platforms can easily be produced and lead to a significant sensor sensitivity gain compared to that of the conventional SPREE surfaces of about four times. We believe that such an enhancement in sensor response could be useful for next generation sensor systems.

  20. Erythrocyte Membrane Failure by Electromechanical Stress

    Directory of Open Access Journals (Sweden)

    E Du

    2018-01-01

    Full Text Available We envision that electrodeformation of biological cells through dielectrophoresis as a new technique to elucidate the mechanistic details underlying membrane failure by electrical and mechanical stresses. Here we demonstrate the full control of cellular uniaxial deformation and tensile recovery in biological cells via amplitude-modified electric field at radio frequency by an interdigitated electrode array in microfluidics. Transient creep and cyclic experiments were performed on individually tracked human erythrocytes. Observations of the viscoelastic-to-viscoplastic deformation behavior and the localized plastic deformations in erythrocyte membranes suggest that electromechanical stress results in irreversible membrane failure. Examples of membrane failure can be separated into different groups according to the loading scenarios: mechanical stiffening, physical damage, morphological transformation from discocyte to echinocyte, and whole cell lysis. These results show that this technique can be potentially utilized to explore membrane failure in erythrocytes affected by other pathophysiological processes.

  1. In-situ membrane hydration measurement of proton exchange membrane fuel cells

    Science.gov (United States)

    Lai, Yeh-Hung; Fly, Gerald W.; Clapham, Shawn

    2015-01-01

    Achieving proper membrane hydration control is one of the most critical aspects of PEM fuel cell development. This article describes the development and application of a novel 50 cm2 fuel cell device to study the in-situ membrane hydration by measuring the through-thickness membrane swelling via an array of linear variable differential transducers. Using this setup either as an air/air (dummy) cell or as a hydrogen/air (operating) cell, we performed a series of hydration and dehydration experiments by cycling the RH of the inlet gas streams at 80 °C. From the linear relationship between the under-the-land swelling and the over-the-channel water content, the mechanical constraint within the fuel cell assembly can suppress the membrane water uptake by 11%-18%. The results from the air/air humidity cycling test show that the membrane can equilibrate within 120 s for all RH conditions and that membrane can reach full hydration at a RH higher than 140% in spite of the use of a liquid water impermeable Carbel MP30Z microporous layer. This result confirms that the U.S. DOE's humidity cycling mechanical durability protocol induces sufficient humidity swings to maximize hygrothermal mechanical stresses. This study shows that the novel experimental technique can provide a robust and accurate means to study the in-situ hydration of thin membranes subject to a wide range of fuel cell conditions.

  2. Thermomechanical Response of Self-Assembled Nanoparticle Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yifan [Department; James; Chan, Henry [Center; Narayanan, Badri [Center; McBride, Sean P. [Department; Sankaranarayanan, Subramanian K. R. S. [Center; Lin, Xiao-Min [Center; Jaeger, Heinrich M. [Department; James

    2017-07-21

    Monolayers composed of colloidal nanoparticles, with a thickness of less than 10 nm, have remarkable mechanical moduli and can suspend over micrometer-sized holes to form free-standing membranes. In this paper, we discuss experiment's and coarse-grained molecular dynamics simulations characterizing the thermomechanical properties of these self-assembled nanoparticle membranes. These membranes remain strong and resilient up to temperatures much higher than previous simulation predictions and exhibit an unexpected hysteretic behavior during the first heating cooling cycle. We show this hysteretic behavior can be explained by an asymmetric ligand configuration from the self assembly process and can be controlled by changing the ligand coverage or cross-linking the ligand molecules. Finally, we show the screening effect of water molecules on the ligand interactions can strongly affect the moduli and thermomechanical behavior.

  3. Theoretical Analysis on Mechanical Deformation of Membrane-Based Photomask Blanks

    Science.gov (United States)

    Marumoto, Kenji; Aya, Sunao; Yabe, Hedeki; Okada, Tatsunori; Sumitani, Hiroaki

    2012-04-01

    Membrane-based photomask is used in proximity X-ray lithography including that in LIGA (Lithographie, Galvanoformung und Abformung) process, and near-field photolithography. In this article, out-of-plane deformation (OPD) and in-plane displacement (IPD) of membrane-based photomask blanks are theoretically analyzed to obtain the mask blanks with flat front surface and low stress absorber film. First, we derived the equations of OPD and IPD for the processing steps of membrane-based photomask such as film deposition, back-etching and bonding, using a theory of symmetrical bending of circular plates with a coaxial circular hole and that of deformation of cylinder under hydrostatic pressure. The validity of the equations was proved by comparing the calculation results with experimental ones. Using these equations, we investigated the relation between the geometry of the mask blanks and the distortions generally, and gave the criterion to attain the flat front surface. Moreover, the absorber stress-bias required to obtain zero-stress on finished mask blanks was also calculated and it has been found that only little stress-bias was required for adequate hole size of support plate.

  4. Development of ultrasonic inspection equipment using phased array method

    International Nuclear Information System (INIS)

    Kikuchi, Osamu; Yamatoya, Naofumi; Umino, Tomohiro; Baba, Atsushi

    2008-01-01

    This study presents new phased array UT equipments, one is developed as portable type for field inspection and the other is developed for 2D-matrix array (3D Focus-UT). The pulser of square burst wave was adopted for these new equipments to enhance flaw echo amplitude. At over 3 cycles of square burst cycle, the authors confirmed over 10 dB enhancement of bottom echo amplitude. Moreover, a new flaw imaging method using S-SAFT was also adopted for equipments to improve SN ratio and flaw echo resolution in inspection image. The authors verified effects of S-SAFT using side drilled hole specimen, about 2 times of improvement of SN ratio and flaw echo resolution. (author)

  5. Thermal physics of transition edge sensor arrays

    International Nuclear Information System (INIS)

    Hoevers, H.F.C.

    2006-01-01

    Thermal transport in transition edge sensor (TES)-based microcalorimeter arrays is reviewed. The fundamentals of thermal conductance in Si 3 N 4 membranes are discussed and the magnitude of the electron-phonon coupling and Kapitza coupling in practical devices is summarized. Next, the thermal transport in high-stopping power and low-heat capacity absorbers, required for arrays of TES microcalorimeters, is discussed in combination with a performance analysis of detectors with mushroom-absorbers. Finally, the phenomenology of unexplained excess noise, observed in both Mo- and Ti-based TESs, is briefly summarized and related with the coupling of the TES to the heat bath

  6. Wafer-Scale High-Throughput Ordered Growth of Vertically Aligned ZnO Nanowire Arrays

    KAUST Repository

    Wei, Yaguang

    2010-09-08

    This article presents an effective approach for patterned growth of vertically aligned ZnO nanowire (NW) arrays with high throughput and low cost at wafer scale without using cleanroom technology. Periodic hole patterns are generated using laser interference lithography on substrates coated with the photoresist SU-8. ZnO NWs are selectively grown through the holes via a low-temperature hydrothermal method without using a catalyst and with a superior control over orientation, location/density, and as-synthesized morphology. The development of textured ZnO seed layers for replacing single crystalline GaN and ZnO substrates extends the large-scale fabrication of vertically aligned ZnO NW arrays on substrates of other materials, such as polymers, Si, and glass. This combined approach demonstrates a novel method of manufacturing large-scale patterned one-dimensional nanostructures on various substrates for applications in energy harvesting, sensing, optoelectronics, and electronic devices. © 2010 American Chemical Society.

  7. Conductivity in the gravity dual to massive ABJM and the membrane paradigm

    International Nuclear Information System (INIS)

    Lopez-Arcos, Cristhiam; Nastase, Horatiu; Rojas, Francisco; Murugan, Jeff

    2014-01-01

    In this paper we analyze the effect of the massive deformation of the ABJM model on the calculation of conductivity of the dual theory. We show that some of the difficulties presented by the dual geometry, in particular the construction of black holes therein, can be at least partially circumvented by adopting a membrane paradigm-like computation of the conductivity, which requires us to know just the effect of the deformation on the horizon of a black hole in AdS 4 . The deformation at the horizon itself is found by first deforming the flat space near the horizon, and then using the corresponding solution near the horizon as initial conditions for the Einstein’s equations. We find the same result, showing an increase in conductivity, using two types of membrane paradigm computations

  8. SHORT-PULSE ELECTROMAGNETIC TRANSPONDER FOR HOLE-TO-HOLE USE.

    Science.gov (United States)

    Wright, David L.; Watts, Raymond D.; Bramsoe, Erik

    1983-01-01

    Hole-to-hole observations were made through nearly 20 m of granite using an electromagnetic transponder (an active reflector) in one borehole and a single-hole short-pulse radar in another. The transponder is inexpensive, operationally simple, and effective in extending the capability of a short-pulse borehole radar system to allow hole-to-hole operation without requiring timing cables. A detector in the transponder senses the arrival of each pulse from the radar. Each pulse detection triggers a kilovolt-amplitude pulse for retransmission. The transponder 'echo' may be stronger than that of a passive reflector by a factor of as much as 120 db. The result is an increase in range capability by a factor which depends on attenuation in the medium and hole-to-hole wavepath geometry.

  9. CLOSING MACULAR HOLES WITH "MACULAR PLUG" WITHOUT GAS TAMPONADE AND POSTOPERATIVE POSTURING.

    Science.gov (United States)

    Chakrabarti, Meena; Benjamin, Preethi; Chakrabarti, Keya; Chakrabarti, Arup

    2017-03-01

    To investigate the surgical results of macular hole surgery without gas tamponade or postoperative posturing in patients with Stage 3 and Stage 4 macular holes with ≥500 μm mean base diameter. Retrospective interventional case series. Twenty-six patients with Stage 3 and Stage 4 macular holes. Twenty-six eyes of 26 patients with Stage 3 and Stage 4 macular holes and a mean base diameter of 892.8 ± 349 μm underwent pars plana 23-gauge vitrectomy with broad internal limiting membrane peel (ILM peel), inverted ILM flap repositioning (ILMR), and use of autologous gluconated blood clumps as a macular plug to close the macular hole. No fluid-air exchange, endotamponade, or postoperative posturing was used. The subjects were followed up for 12 months. The anatomical outcome of the procedure was evaluated by fundus examination and optical coherence tomography. Spectral domain optical coherence tomography was used to study the restoration of the outer retinal layer integrity in the postoperative period. The preoperative and postoperative best-corrected visual acuities in logMAR units were compared to evaluate functional outcome. Macular hole closure and best-corrected visual acuity before and after surgery. Twenty-six patients with mean age 62.8 ± 7.3 years, preoperative median best-corrected visual acuity 6/60 (1.0 logMAR units), and a mean base diameter of 892.8 ± 349 μm underwent surgery to close macular holes without gas tamponade or postoperative posturing. Twenty patients (76.9%) were phakic. Twenty eyes (76.92%) had Stage 3 macular holes and 6 eyes (23.10%) had Stage 4 macular holes. After a single surgery, hole closure was achieved in 100% of eyes. The median best-corrected visual acuity improved from 6/60 (1.0 logMAR units) to 6/18 (0.50 logMAR units) (P hole closure with statically significant functional improvement for large Stage 3 and Stage 4 macular holes.

  10. Networked Rectenna Array for Smart Material Actuators

    Science.gov (United States)

    Choi, Sang H.; Golembiewski, Walter T.; Song, Kyo D.

    2000-01-01

    The concept of microwave-driven smart material actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. Networked rectenna patch array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is adopted for networking a rectenna/actuator patch array. The PAD circuit is imbedded into a single embodiment of rectenna and actuator array. The thin-film microcircuit embodiment of PAD circuit adds insignificant amount of rigidity to membrane flexibility. Preliminary design and fabrication of PAD circuitry that consists of a few nodal elements were made for laboratory testing. The networked actuators were tested to correlate the network coupling effect, power allocation and distribution, and response time. The features of preliminary design are 16-channel computer control of actuators by a PCI board and the compensator for a power failure or leakage of one or more rectennas.

  11. Airfoil-shaped micro-mixers for reducing fouling on membrane surfaces

    Science.gov (United States)

    Ho, Clifford K; Altman, Susan J; Clem, Paul G; Hibbs, Michael; Cook, Adam W

    2012-10-23

    An array of airfoil-shaped micro-mixers that enhances fluid mixing within permeable membrane channels, such as used in reverse-osmosis filtration units, while minimizing additional pressure drop. The enhanced mixing reduces fouling of the membrane surfaces. The airfoil-shaped micro-mixer can also be coated with or comprised of biofouling-resistant (biocidal/germicidal) ingredients.

  12. Black holes

    OpenAIRE

    Brügmann, B.; Ghez, A. M.; Greiner, J.

    2001-01-01

    Recent progress in black hole research is illustrated by three examples. We discuss the observational challenges that were met to show that a supermassive black hole exists at the center of our galaxy. Stellar-size black holes have been studied in x-ray binaries and microquasars. Finally, numerical simulations have become possible for the merger of black hole binaries.

  13. Fabrication and characterization of magnetic composite membrane pressure sensor

    KAUST Repository

    Khan, Mohammed Asadullah

    2016-04-20

    This paper describes a magnetic field powered pressure sensor, which comprises a coil array and a magnetic composite membrane. The composite membrane is made by embedding a ribbon of the amorphous soft magnetic alloy Vitrovac®, in a 17 mm x 25 mm x 1.5 mm Polydimethylsiloxane (PDMS) layer. PDMS is chosen for its low Young\\'s modulus and the amorphous alloy for its high permeability. The membrane is suspended 1.5 mm above a 17x19 array of microfabricated planar coils. The coils are fabricated by patterning a 620 nm thick gold layer. Each coil occupies an area of 36000 μm2 and consists of 14 turns. The sensor is tested by subjecting it to pressure and simultaneously exciting it by a 24 A/m, 100 kHz magnetic field. A pressure change from 0 kPa to 5.1 kPa, results in a 5400 ppm change in the voltage output.

  14. Fabrication and characterization of magnetic composite membrane pressure sensor

    KAUST Repository

    Khan, Mohammed Asadullah; Alfadhel, Ahmed; Kosel, Jü rgen; Bakolka, M.

    2016-01-01

    This paper describes a magnetic field powered pressure sensor, which comprises a coil array and a magnetic composite membrane. The composite membrane is made by embedding a ribbon of the amorphous soft magnetic alloy Vitrovac®, in a 17 mm x 25 mm x 1.5 mm Polydimethylsiloxane (PDMS) layer. PDMS is chosen for its low Young's modulus and the amorphous alloy for its high permeability. The membrane is suspended 1.5 mm above a 17x19 array of microfabricated planar coils. The coils are fabricated by patterning a 620 nm thick gold layer. Each coil occupies an area of 36000 μm2 and consists of 14 turns. The sensor is tested by subjecting it to pressure and simultaneously exciting it by a 24 A/m, 100 kHz magnetic field. A pressure change from 0 kPa to 5.1 kPa, results in a 5400 ppm change in the voltage output.

  15. Detecting stochastic backgrounds of gravitational waves with pulsar timing arrays

    Science.gov (United States)

    Siemens, Xavier

    2016-03-01

    For the past decade the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has been using the Green Bank Telescope and the Arecibo Observatory to monitor millisecond pulsars. NANOGrav, along with two other international collaborations, the European Pulsar Timing Array and the Parkes Pulsar Timing Array in Australia, form a consortium of consortia: the International Pulsar Timing Array (IPTA). The goal of the IPTA is to directly detect low-frequency gravitational waves which cause small changes to the times of arrival of radio pulses from millisecond pulsars. In this talk I will discuss the work of NANOGrav and the IPTA, as well as our sensitivity to stochastic backgrounds of gravitational waves. I will show that a detection of the background produced by supermassive black hole binaries is possible by the end of the decade. Supported by the NANOGrav Physics Frontiers Center.

  16. Association between fundus autofluorescence and visual outcome in surgically closed macular holes.

    Science.gov (United States)

    Lee, Young Seob; Yu, Seung-Young; Cho, Nam Suk; Kim, Moo Sang; Kim, Young Gyun; Kim, Eung Suk; Kwak, Hyung Woo

    2013-06-01

    To investigate the association between fundus autofluorescence (FAF) and visual acuity, recovery of foveal microstructure, and FAF in surgically closed macular holes. Twenty-six eyes with surgically closed macular hole were classified into two groups based on foveal FAF: normal autofluorescence (NAF) or increased autofluorescence (IAF). The association between foveal FAF and visual acuity was analyzed. In addition, we examined the relationship between recovery of the foveal microstructure assessed by spectral domain optical coherence tomography and FAF after macular hole surgery. At 1 month and 6 months after surgery, there were 9 NAF eyes and 17 IAF eyes. There were no differences between NAF and IAF eyes at 1 month and 6 months after surgery. Preoperative best-corrected visual acuity (logarithm of the minimum angle of resolution) did not differ between groups. Best-corrected visual acuity was significantly higher in the NAF group than in the IAF group at 1 month postoperatively (0.59 ± 0.34 vs. 0.91 ± 0.36, P = 0.044) and tended to be higher at 6 months (0.37 ± 0.38 vs. 0.69 ± 0.53, P = 0.126). Restoration of photoreceptor external limiting membrane differed significantly in 8 NAF eyes (89%) and 4 IAF eyes (24%) at postoperation 1 month (P = 0.001). After 6 months, external limiting membrane was restored in all 9 NAF eyes (100%) and in only 11 IAF eyes (65%) (P = 0.042). Fundus autofluorescence findings observed in surgically closed macular holes correlated with visual improvement and photoreceptor status. Eyes with visual improvement had restoration of normal foveal autofluorescence and retinal microstructure, whereas eyes with persistent foveal hyperautofluorescence did not achieve complete restoration of the retinal microstructure, and visual improvement was not as significant.

  17. The entropy of Garfinkle-Horne dilaton black hole due to arbitrary spin fields

    Institute of Scientific and Technical Information of China (English)

    SHEN; Yougen(沈有根)

    2002-01-01

    Using the membrane model which is based on brick wall model, we calculated the free energy and entropy of Garfinkle-Horne dilatonic black hole due to arbitrary spin fields. The result shows that the entropy of scalar field and the entropy of Fermionic field have similar formulas. There is only a coefficient between them.

  18. Retinal displacement toward optic disc after internal limiting membrane peeling for idiopathic macular hole.

    Science.gov (United States)

    Ishida, Masahiro; Ichikawa, Yoshikazu; Higashida, Rieko; Tsutsumi, Yorihisa; Ishikawa, Atsushi; Imamura, Yutaka

    2014-05-01

    To examine the retinal displacement following successful macular hole (MH) surgery with internal limiting membrane (ILM) peeling and gas tamponade, and to determine the correlation between the extent of displacement and the basal MH size. Retrospective, interventional, observational case series. The medical records of consecutive patients with an idiopathic MH that had undergone vitrectomy with ILM peeling and gas tamponade were studied. The distances between the optic disc and the intersection of 2 retinal vessels located nasal or temporal to the fovea were measured manually preoperatively (A), and 2 weeks and 1, 3, 6, and 12 months postoperatively (B), on the fundus autofluorescence or near-infrared images. The basal and minimum diameters of the MHs were measured in the spectral-domain optical coherence tomographic images. The correlations between the ratio of the retinal displacement (A - B/A) and basal diameters of the MHs were determined. Twenty-one eyes of 21 patients (9 men, mean age: 64.6 ± 8.4 years) were studied. Ten eyes (47.6%) had stage 2 MH, 9 eyes (42.9%) had stage 3 MH, and 2 eyes (9.5%) had stage 4 MH. The temporal retinal vessels were displaced 260.8 ± 145.8 μm toward the optic disc at 2 weeks postoperatively, which was significantly greater than the 91.1 ± 89.7 μm of the nasal retinal vessels (paired t test, P displacement in the temporal field at 2 weeks was significantly correlated with the basal diameter of the MH (Spearman's rank correlation coeffieient = -0.476, P = .033. The greater displacement of the temporal retina than the nasal retina toward the optic disc postoperatively suggests that the temporal retina is more flexible and can be retracted toward the optic disc during the MH closure. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. A 90 element CdTe array detector

    Energy Technology Data Exchange (ETDEWEB)

    Iwase, Y.; Onozuka, A.; Ohmori, M. (Nippon Mining Co. Ltd., Toda, Saitama (Japan). Electronic Material and Components Labs.); Funaki, M. (Nippon Mining Co. Ltd., Toda, Saitama (Japan). Materials Development Research Labs.)

    1992-11-15

    The fabrication of a CdTe array radiation detector and its radiation detection characteristics are described. In order to obtain high efficiency of charge collection and realize uniform detection sensitivity, current-voltage characteristics with the combination of large and small barrier height contacts and three kinds of CdTe crystals have been investigated. It was found that the Schottky barrier height of electroless Pt deposition was 0.97 eV, which effectively suppressed electron injection. By using the crystal grown by the travelling heater method with a Cl concentration of 2 ppm, carrier lifetimes for electrons and holes of 1.0 and 0.5 [mu]s, respectively, were achieved. A 90 element array detector exhibited an energy resolution as low as 4.5 keV and a count rate variation of less than 5% for 60 keV [gamma]-rays. (orig.).

  20. A 90 element CdTe array detector

    Science.gov (United States)

    Iwase, Y.; Funaki, M.; Onozuka, A.; Ohmori, M.

    1992-11-01

    The fabrication of a CdTe array radiation detector and its radiation detection characteristics are described. In order to obtain high efficiency of charge collection and realize uniform detection sensitivity, current-voltage characteristics with the combination of large and small barrier height contacts and three kinds of CdTe crystals have been investigated. It was found that the Schottky barrier height of electroless Pt deposition was 0.97 eV, which effectively suppressed electron injection. By using the crystal grown by the travelling heater method with a Cl concentration of 2 ppm, carrier lifetimes for electrons and holes of 1.0 and 0.5 μs, respectively, were achieved. A 90 element array detector exhibited an energy resolution as low as 4.5 keV and a count rate variation of less than 5% for 60 keV γ-rays.

  1. Fabrication of microlens arrays using a CO2-assisted embossing technique

    International Nuclear Information System (INIS)

    Huang, Tzu-Chien; Chan, Bin-Da; Ciou, Jyun-Kai; Yang, Sen-Yeu

    2009-01-01

    This paper reports a method to fabricate microlens arrays with a low processing temperature and a low pressure. The method is based on embossing a softened polymeric substrate over a mold with micro-hole arrays. Due to the effect of capillary and surface tension, microlens arrays can be formed. The embossing medium is CO 2 gas, which supplies a uniform pressing pressure so that large-area microlens arrays can be fabricated. CO 2 gas also acts as a solvent to plasticize the polymer substrates. With the special dissolving ability and isotropic pressing capacity of CO 2 gas, microlens arrays can be fabricated at a low temperature (lower than T g ) and free of thermal-induced residual stress. Such a combined mechanism of dissolving and embossing with CO 2 gas makes the fabrication of microlens arrays direct with complex processes, and is more compatible for optical usage. In the study, it is also found that the sag height of microlens changes when different CO 2 dissolving pressure and time are used. This makes it easy to fabricate microlens arrays of different geometries without using different molds. The quality, uniformity and optical property of the fabricated microlens arrays have been verified with measurements of the dimensions, surface smoothness, focal length, transmittance and light intensity through the fabricated microlens arrays

  2. Biomimetic devices functionalized by membrane channel proteins

    Science.gov (United States)

    Schmidt, Jacob

    2004-03-01

    We are developing a new family of active materials which derive their functional properties from membrane proteins. These materials have two primary components: the proteins and the membranes themselves. I will discuss our recent work directed toward development of a generic platform for a "plug-and-play" philosophy of membrane protein engineering. By creating a stable biomimetic polymer membrane a single molecular monolayer thick, we will enable the exploitation of the function of any membrane protein, from pores and pumps to sensors and energy transducers. Our initial work has centered on the creation, study, and characterization of the biomimetic membranes. We are attempting to make large areas of membrane monolayers using Langmuir-Blodgett film formation as well as through arrays of microfabricated black lipid membrane-type septa. A number of techniques allow the insertion of protein into the membranes. As a benchmark, we have been employing a model system of voltage-gated pore proteins, which have electrically controllable porosities. I will report on the progress of this work, the characterization of the membranes, protein insertion processes, and the yield and functionality of the composite.

  3. Neutrino constraints that transform black holes into grey holes

    International Nuclear Information System (INIS)

    Ruderfer, M.

    1982-01-01

    Existing black hole theory is found to be defective in its neglect of the physical properties of matter and radiation at superhigh densities. Nongravitational neutrino effects are shown to be physically relevant to the evolution of astronomical black holes and their equations of state. Gravitational collapse to supernovae combined with the Davis and Ray vacuum solution for neutrinos limit attainment of a singularity and require black holes to evolve into ''grey holes''. These allow a better justification than do black holes for explaining the unique existence of galactic masses. (Auth.)

  4. A preliminary study of aquaporin 1 immunolocalization in chronic subdural hematoma membranes.

    Science.gov (United States)

    Basaldella, Luca; Perin, Alessandro; Orvieto, Enrico; Marton, Elisabetta; Itskevich, David; Dei Tos, Angelo Paolo; Longatti, Pierluigi

    2010-07-01

    Aquaporin 1 (AQP1) is a molecular water channel expressed in many anatomical locations, particularly in epithelial barriers specialized in water transport. The aim of this study was to investigate AQP1 expression in chronic subdural hematoma (CSDH) membranes. In this preliminary study, 11 patients with CSDH underwent burr hole craniectomy and drainage. Membrane specimens were stained with a monoclonal antibody targeting AQP1 for immunohistochemical analysis. The endothelial cells of the sinusoid capillaries of the outer membranes exhibited an elevated immunoreactivity to AQP1 antibody compared to the staining intensity of specimens from the inner membrane and normal dura. These findings suggest that the outer membrane might be the source of the increased fluid accumulation responsible for chronic hematoma enlargement.

  5. Vortex dynamics in spacing-graded array of defects on a niobium film

    International Nuclear Information System (INIS)

    Wu, T.C.; Horng, Lance; Wu, J.C.; Hsiao, C.W.; Kolacek, Jan; Yang, T.J.

    2006-01-01

    We have investigated the vortex dynamics in the niobium films having a spacing-graded array of pinning sites. The samples were fabricated by using electron beam lithography through a lift-off technique. The pinning sites of 200 nm in diameter were arranged with a constant hole-defect separation in x-axis direction and graded separation in y-axis direction from 392 nm to 408 nm. The magnetoresistance measurements and current-voltage characteristics were explored with the external magnetic field applied perpendicular to the film plane. Dc current-voltage measured at matching field revealed two distinct curves resulted from the positive and negative applied current directions, respectively. This is believed to be due to an asymmetry pinning potential formed in the spacing-graded array of holes, giving rise to asymmetry Lorentz forces. Dc voltage drop measured with respect to the ac current applied along the x-axis of the sample showed two separated maxima, which can be explained using the dynamics of pinned vortex lattice and interstitial vortices in the asymmetry pinning landscape

  6. Amplitude-phase characteristics of electromagnetic fields diffracted by a hole in a thin film with realistic optical properties

    Science.gov (United States)

    Dorofeyev, Illarion

    2009-03-01

    Characteristics of a quasi-spherical wave front of an electromagnetic field diffracted by a subwavelength hole in a thin film with real optical properties are studied. Related diffraction problem is solved in general by use of the scalar and vector Green's theorems and related Green's function of a boundary-value problem. Local phase deviations of a diffracted wave front from an ideal spherical front are calculated. Diffracted patterns are calculated for the coherent incident fields in case of holes array in a screen of perfect conductivity.

  7. Macular hole surgery with short-acting gas and short-duration face-down positioning

    Directory of Open Access Journals (Sweden)

    Xirou T

    2012-07-01

    Full Text Available Tina Xirou,1 Panagiotis G Theodossiadis,2 Michael Apostolopoulos,3 A Stamatina Kabanarou,1 Elias Feretis,1 Ioannis D Ladas,3 Chrysanthi Koutsandrea31Vitreoretinal Unit, Red Cross Hospital, 2B Department of Ophthalmology, University of Athens, Greece; 3A Department of Ophthalmology, University of Athens, GreecePurpose: To report on the outcomes of vitrectomy and sulfur hexafluoride (SF6 gas tamponade for idiopathic macular holes with 2 days of face-down positioning.Patients and methods: This was a prospective, nonrandomized, observational sequential case-series study on 23 consecutive patients receiving macular hole surgery using 20% SF6 and advised to stay in a face-down position for 2 days postoperatively (SF6 group. These patients were compared to 23 consecutive patients who had previously undergone macular hole surgery, had received 14% C3F8, and were advised to maintain a face-down position for 2 days (C3F8 group. Patients in both groups underwent vitrectomy, internal limiting membrane peeling, and fluid gas exchange using either SF6 or C3F8. Preoperative and postoperative data included best corrected visual acuity recorded in LogMAR units, slit-lamp biomicroscopy, and optical coherence tomography.Results: At a 6-month follow-up, macular hole closure was noted in 23/23 eyes (100% and in 22/23 eyes (96% in the SF6 and C3F8 groups, respectively. The improvement in visual acuity (measured through Snellen acuity lines both preoperatively until 6 months postoperatively was 4.08 ± 2.31 (95% confidence interval [CI]: 3.08–5.08 for the SF6 group and 2.87 ± 2.30 (95% CI: 1.87–3.86 for the C3F8 group; this difference was not statistically significant (P = 0.06.Conclusion: Vitrectomy with internal limiting membrane peeling and a short-acting gas tamponade using SF6 with posture limitation for 2 days may give a high success rate in macular hole surgery.Keywords: idiopathic macular holes, SF6 gas tamponade, C3F8 gas tamponade

  8. Photoconductivity of Germanium Nanowire Arrays Incorporated in Anodic Aluminum Oxide

    International Nuclear Information System (INIS)

    Polyakov, B; Prikulis, J; Grigorjeva, L; Millers, D; Daly, B; Holmes, J D; Erts, D

    2007-01-01

    Photoconductivity of germanium nanowire arrays of 50 and 100 nm diameter incorporated into Anodic Aluminum Oxide (AAO) membranes illuminated with visible light is investigated. Photocurrent response to excitation radiation with time constants faster than 10 -4 s were governed by absorption of incident light by nanowires, while photokinetics with time constants of the order of 10 -3 s originates from the photoluminescence of the AAO matrix. Possible applications of nanowire arrays inside AAO as photoresistors are discussed

  9. Nanopillar arrays of amorphous carbon nitride

    Science.gov (United States)

    Sai Krishna, Katla; Pavan Kumar, B. V. V. S.; Eswaramoorthy, Muthusamy

    2011-07-01

    Nanopillar arrays of amorphous carbon nitride have been prepared using anodic aluminum oxide (AAO) membrane as a template. The amine groups present on the surface of these nanopillars were exploited for functionalization with oleic acid in order to stabilize the nanostructure at the aqueous-organic interface and also for the immobilization of metal nanoparticles and protein. These immobilised nanoparticles were found to have good catalytic activity.

  10. Macular hole-associated retinal detachment in Best vitelliform dystrophy: Series of two cases and literature review

    Science.gov (United States)

    Tewari, Ruchir; Kumar, Vinod; Ravani, Raghav; Dubey, Devashish; Chandra, Parijat; Kumar, Atul

    2018-01-01

    Two eyes of 2 patients with macular hole-associated retinal detachment in clinically diagnosed vitelliruptive stage of Best vitelliform dystrophy were surgically managed by 25-gauge sutureless pars plana vitrectomy, internal limiting membrane (ILM) peeling with inverted ILM flap, and short-acting (SF6) gas tamponade. The patients were assessed with respect to best-corrected visual acuity, color fundus photographs, shortwave fundus autofluorescence, and swept source optical coherence tomography. Surgical intervention led to Type 1 closure of macular hole, resolution of retinal detachment, and improvement in vision in both patients. PMID:29676326

  11. Macular hole-associated retinal detachment in Best vitelliform dystrophy: Series of two cases and literature review

    Directory of Open Access Journals (Sweden)

    Ruchir Tewari

    2018-01-01

    Full Text Available Two eyes of 2 patients with macular hole-associated retinal detachment in clinically diagnosed vitelliruptive stage of Best vitelliform dystrophy were surgically managed by 25-gauge sutureless pars plana vitrectomy, internal limiting membrane (ILM peeling with inverted ILM flap, and short-acting (SF6 gas tamponade. The patients were assessed with respect to best-corrected visual acuity, color fundus photographs, shortwave fundus autofluorescence, and swept source optical coherence tomography. Surgical intervention led to Type 1 closure of macular hole, resolution of retinal detachment, and improvement in vision in both patients.

  12. Diffraction of stochastic electromagnetic fields by a hole in a thin film with real optical properties

    Science.gov (United States)

    Dorofeyev, Illarion

    2008-08-01

    The classical Kirchhoff theory of diffraction is extended to the case of real optical properties of a screen and its finite thickness. A spectral power density of diffracted electromagnetic fields by a hole in a thin film with real optical properties was calculated. The problem was solved by use of the vector Green theorems and related Green function of the boundary value problem. A spectral and spatial selectivity of the considered system was demonstrated. Diffracted patterns were calculated for the coherent and incoherent incident fields in case of holes array in a screen of perfect conductivity.

  13. Diffraction of stochastic electromagnetic fields by a hole in a thin film with real optical properties

    International Nuclear Information System (INIS)

    Dorofeyev, Illarion

    2008-01-01

    The classical Kirchhoff theory of diffraction is extended to the case of real optical properties of a screen and its finite thickness. A spectral power density of diffracted electromagnetic fields by a hole in a thin film with real optical properties was calculated. The problem was solved by use of the vector Green theorems and related Green function of the boundary value problem. A spectral and spatial selectivity of the considered system was demonstrated. Diffracted patterns were calculated for the coherent and incoherent incident fields in case of holes array in a screen of perfect conductivity

  14. Primary black holes

    International Nuclear Information System (INIS)

    Novikov, I.; Polnarev, A.

    1981-01-01

    Proves are searched for of the formation of the so-called primary black holes at the very origin of the universe. The black holes would weigh less than 10 13 kg. The formation of a primary black hole is conditional on strong fluctuations of the gravitational field corresponding roughly to a half of the fluctuation maximally permissible by the general relativity theory. Only big fluctuations of the gravitational field can overcome the forces of the hot gas pressure and compress the originally expanding matter into a black hole. Low-mass black holes have a temperature exceeding that of the black holes formed from stars. A quantum process of particle formation, the so-called evaporation takes place in the strong gravitational field of a black hole. The lower the mass of the black hole, the shorter the evaporation time. The analyses of processes taking place during the evaporation of low-mass primary black holes show that only a very small proportion of the total mass of the matter in the universe could turn into primary black holes. (M.D.)

  15. Optimization of the short-circuit current in an InP nanowire array solar cell through opto-electronic modeling.

    Science.gov (United States)

    Chen, Yang; Kivisaari, Pyry; Pistol, Mats-Erik; Anttu, Nicklas

    2016-09-23

    InP nanowire arrays with axial p-i-n junctions are promising devices for next-generation photovoltaics, with a demonstrated efficiency of 13.8%. However, the short-circuit current in such arrays does not match their absorption performance. Here, through combined optical and electrical modeling, we study how the absorption of photons and separation of the resulting photogenerated electron-hole pairs define and limit the short-circuit current in the nanowires. We identify how photogenerated minority carriers in the top n segment (i.e. holes) diffuse to the ohmic top contact where they recombine without contributing to the short-circuit current. In our modeling, such contact recombination can lead to a 60% drop in the short-circuit current. To hinder such hole diffusion, we include a gradient doping profile in the n segment to create a front surface barrier. This approach leads to a modest 5% increase in the short-circuit current, limited by Auger recombination with increased doping. A more efficient approach is to switch the n segment to a material with a higher band gap, like GaP. Then, a much smaller number of holes is photogenerated in the n segment, strongly limiting the amount that can diffuse and disappear into the top contact. For a 500 nm long top segment, the GaP approach leads to a 50% higher short-circuit current than with an InP top segment. Such a long top segment could facilitate the fabrication and contacting of nanowire array solar cells. Such design schemes for managing minority carriers could open the door to higher performance in single- and multi-junction nanowire-based solar cells.

  16. From binary black hole simulation to triple black hole simulation

    International Nuclear Information System (INIS)

    Bai Shan; Cao Zhoujian; Han, Wen-Biao; Lin, Chun-Yu; Yo, Hwei-Jang; Yu, Jui-Ping

    2011-01-01

    Black hole systems are among the most promising sources for a gravitational wave detection project. Now, China is planning to construct a space-based laser interferometric detector as a follow-on mission of LISA in the near future. Aiming to provide some theoretical support to this detection project on the numerical relativity side, we focus on black hole systems simulation in this work. Considering the globular galaxy, multiple black hole systems also likely to exist in our universe and play a role as a source for the gravitational wave detector we are considering. We will give a progress report in this paper on our black hole system simulation. More specifically, we will present triple black hole simulation together with binary black hole simulation. On triple black hole simulations, one novel perturbational method is proposed.

  17. A Note on the Observational Evidence for the Existence of Event Horizons in Astrophysical Black Hole Candidates

    Directory of Open Access Journals (Sweden)

    Cosimo Bambi

    2013-01-01

    Full Text Available Black holes have the peculiar and intriguing property of having an event horizon, a one-way membrane causally separating their internal region from the rest of the Universe. Today, astrophysical observations provide some evidence for the existence of event horizons in astrophysical black hole candidates. In this short paper, I compare the constraint we can infer from the nonobservation of electromagnetic radiation from the putative surface of these objects with the bound coming from the ergoregion instability, pointing out the respective assumptions and limitations.

  18. A note on the observational evidence for the existence of event horizons in astrophysical black hole candidates.

    Science.gov (United States)

    Bambi, Cosimo

    2013-01-01

    Black holes have the peculiar and intriguing property of having an event horizon, a one-way membrane causally separating their internal region from the rest of the Universe. Today, astrophysical observations provide some evidence for the existence of event horizons in astrophysical black hole candidates. In this short paper, I compare the constraint we can infer from the nonobservation of electromagnetic radiation from the putative surface of these objects with the bound coming from the ergoregion instability, pointing out the respective assumptions and limitations.

  19. TOPOGRAPHIC CHANGES OF THE MACULA AFTER CLOSURE OF IDIOPATHIC MACULAR HOLE.

    Science.gov (United States)

    Pak, Kang Yeun; Park, Keun Heung; Kim, Kyong Ho; Park, Sung Who; Byon, Ik Soo; Kim, Hyun Woong; Chung, In Young; Lee, Joo Eun; Lee, Sang Joon; Lee, Ji Eun

    2017-04-01

    To investigate retinal displacement in the macula after surgical closure of idiopathic macular hole and to identify factors correlated with displacement. This retrospective multicenter study included 73 eyes of 73 patients having idiopathic macular hole. A custom program was developed to compare the position of the retinal vessels in the macula between preoperative and postoperative photographs. En face images of a 6 mm × 6 mm optical coherence tomography volume scans were registered to calculate the scale. A grid comprising 16 sectors in 2 rings (inner; 2-4 mm and outer; 4-6 mm) was superimposed. The displacement of the retinal vessels was measured as a vector value by comparing the location of the retinal vessels in each sector. The correlation between displacement and various clinical parameters was analyzed. The average displacement was 57.2 μm at an angle of -3.3° (nasal and slightly inferior). Displacement was larger in the inner ring (79.2 μm) than in the outer ring (35.3 μm, P macula was displaced centripetally, nasally, and slightly inferiorly after surgical closure of idiopathic macular hole. Hole closure, contraction of the nerve fiber layer, and gravity are the suggested mechanisms of macular displacement caused by internal limiting membrane peeling.

  20. Phase transition for black holes with scalar hair and topological black holes

    International Nuclear Information System (INIS)

    Myung, Yun Soo

    2008-01-01

    We study phase transitions between black holes with scalar hair and topological black holes in asymptotically anti-de Sitter spacetimes. As the ground state solutions, we introduce the non-rotating BTZ black hole in three dimensions and topological black hole with hyperbolic horizon in four dimensions. For the temperature matching only, we show that the phase transition between black hole with scalar hair (Martinez-Troncoso-Zanelli black hole) and topological black hole is second-order by using differences between two free energies. However, we do not identify what order of the phase transition between scalar and non-rotating BTZ black holes occurs in three dimensions, although there exists a possible decay of scalar black hole to non-rotating BTZ black hole

  1. Black Holes

    OpenAIRE

    Townsend, P. K.

    1997-01-01

    This paper is concerned with several not-quantum aspects of black holes, with emphasis on theoretical and mathematical issues related to numerical modeling of black hole space-times. Part of the material has a review character, but some new results or proposals are also presented. We review the experimental evidence for existence of black holes. We propose a definition of black hole region for any theory governed by a symmetric hyperbolic system of equations. Our definition reproduces the usu...

  2. Fabrication of arrays of metal and metal oxide nanotubes by shadow evaporation.

    Science.gov (United States)

    Dickey, Michael D; Weiss, Emily A; Smythe, Elizabeth J; Chiechi, Ryan C; Capasso, Federico; Whitesides, George M

    2008-04-01

    This paper describes a simple technique for fabricating uniform arrays of metal and metal oxide nanotubes with controlled heights and diameters. The technique involves depositing material onto an anodized aluminum oxide (AAO) membrane template using a collimated electron beam evaporation source. The evaporating material enters the porous openings of the AAO membrane and deposits onto the walls of the pores. The membrane is tilted with respect to the column of evaporating material, so the shadows cast by the openings of the pores onto the inside walls of the pores define the geometry of the tubes. Rotation of the membrane during evaporation ensures uniform deposition inside the pores. After evaporation, dissolution of the AAO in base easily removes the template to yield an array of nanotubes connected by a thin backing of the same metal or metal oxide. The diameter of the pores dictates the diameter of the tubes, and the incident angle of evaporation determines the height of the tubes. Tubes up to approximately 1.5 mum in height and 20-200 nm in diameter were fabricated. This method is adaptable to any material that can be vapor-deposited, including indium-tin oxide (ITO), a conductive, transparent material that is useful for many opto-electronic applications. An array of gold nanotubes produced by this technique served as a substrate for surface-enhanced Raman spectroscopy: the Raman signal (per molecule) from a monolayer of benzenethiolate was a factor of approximately 5 x 10(5) greater than that obtained using bulk liquid benzenethiol.

  3. Gravitational waves at interferometer scales and primordial black holes in axion inflation

    Energy Technology Data Exchange (ETDEWEB)

    García-Bellido, Juan [Instituto de Física Teórica UAM-CSIC, Universidad Autonóma de Madrid, Cantoblanco, Madrid, 28049 (Spain); Peloso, Marco; Unal, Caner, E-mail: juan.garciabellido@uam.es, E-mail: peloso@physics.umn.edu, E-mail: unal@physics.umn.edu [School of Physics and Astronomy, and Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, 55455 (United States)

    2016-12-01

    We study the prospects of detection at terrestrial and space interferometers, as well as at pulsar timing array experiments, of a stochastic gravitational wave background which can be produced in models of axion inflation. This potential signal, and the development of these experiments, open a new window on inflation on scales much smaller than those currently probed with Cosmic Microwave Background and Large Scale Structure measurements. The sourced signal generated in axion inflation is an ideal candidate for such searches, since it naturally grows at small scales, and it has specific properties (chirality and non-gaussianity) that can distinguish it from an astrophysical background. We study under which conditions such a signal can be produced at an observable level, without the simultaneous overproduction of scalar perturbations in excess of what is allowed by the primordial black hole limits. We also explore the possibility that scalar perturbations generated in a modified version of this model may provide a distribution of primordial black holes compatible with the current bounds, that can act as a seeds of the present black holes in the universe.

  4. The actin homologue MreB organizes the bacterial cell membrane.

    Science.gov (United States)

    Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W

    2014-03-07

    The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes.

  5. Protein diffusion in plant cell plasma membranes: the cell-wall corral.

    Science.gov (United States)

    Martinière, Alexandre; Runions, John

    2013-01-01

    Studying protein diffusion informs us about how proteins interact with their environment. Work on protein diffusion over the last several decades has illustrated the complex nature of biological lipid bilayers. The plasma membrane contains an array of membrane-spanning proteins or proteins with peripheral membrane associations. Maintenance of plasma membrane microstructure can be via physical features that provide intrinsic ordering such as lipid microdomains, or from membrane-associated structures such as the cytoskeleton. Recent evidence indicates, that in the case of plant cells, the cell wall seems to be a major player in maintaining plasma membrane microstructure. This interconnection / interaction between cell-wall and plasma membrane proteins most likely plays an important role in signal transduction, cell growth, and cell physiological responses to the environment.

  6. DNA electrophoresis through microlithographic arrays

    International Nuclear Information System (INIS)

    Sevick, E.M.; Williams, D.R.M.

    1996-01-01

    Electrophoresis is one of the most widely used techniques in biochemistry and genetics for size-separating charged molecular chains such as DNA or synthetic polyelectrolytes. The separation is achieved by driving the chains through a gel with an external electric field. As a result of the field and the obstacles that the medium provides, the chains have different mobilities and are physically separated after a given process time. The macroscopically observed mobility scales inversely with chain size: small molecules move through the medium quickly while larger molecules move more slowly. However, electrophoresis remains a tool that has yet to be optimised for most efficient size separation of polyelectrolytes, particularly large polyelectrolytes, e.g. DNA in excess of 30-50 kbp. Microlithographic arrays etched with an ordered pattern of obstacles provide an attractive alternative to gel media and provide wider avenues for size separation of polyelectrolytes and promote a better understanding of the separation process. Its advantages over gels are (1) the ordered array is durable and can be re-used, (2) the array morphology is ordered and can be standardized for specific separation, and (3) calibration with a marker polyelectrolyte is not required as the array is reproduced to high precision. Most importantly, the array geometry can be graduated along the chip so as to expand the size-dependent regime over larger chain lengths and postpone saturation. In order to predict the effect of obstacles upon the chain-length dependence in mobility and hence, size separation, we study the dynamics of single chains using theory and simulation. We present recent work describing: 1) the release kinetics of a single DNA molecule hooked around a point, frictionless obstacle and in both weak and strong field limits, 2) the mobility of a chain impinging upon point obstacles in an ordered array of obstacles, demonstrating the wide range of interactions possible between the chain and

  7. The Astrophysics of Merging Black Holes

    Science.gov (United States)

    Schnittman, Jeremy D.

    2011-01-01

    When two supermassive black holes (SMBHs) approach within 1-10 mpc, gravitational wave (GW) losses begin to dominate the evolution of the binary, pushing the system to merge in a relatively small time. During this final inspiral regime, the system will emit copious energy in GWs, which should be directly detectable by pulsar timing arrays and space-based interferometers. At the same time, any gas or stars in the immediate vicinity of the merging 5MBHs can get heated and produce bright electromagnetic (EM) counterparts to the GW signals. We present here a number of possible mechanisms by which simultaneous EM and GW signals will yield valuable new information about galaxy evolution, accretion disk dynamics, and fundamental physics in the most extreme gravitational fields.

  8. Low-mass black holes as the remnants of primordial black hole formation.

    Science.gov (United States)

    Greene, Jenny E

    2012-01-01

    Bridging the gap between the approximately ten solar mass 'stellar mass' black holes and the 'supermassive' black holes of millions to billions of solar masses are the elusive 'intermediate-mass' black holes. Their discovery is key to understanding whether supermassive black holes can grow from stellar-mass black holes or whether a more exotic process accelerated their growth soon after the Big Bang. Currently, tentative evidence suggests that the progenitors of supermassive black holes were formed as ∼10(4)-10(5) M(⊙) black holes via the direct collapse of gas. Ongoing searches for intermediate-mass black holes at galaxy centres will help shed light on this formation mechanism.

  9. Progressive atrophy of retinal pigment epithelium after trypan-blue-assisted ILM peeling for macular hole surgery

    Directory of Open Access Journals (Sweden)

    Sachin Jain

    2013-01-01

    Full Text Available We report a case of progressive atrophy of the retinal pigment epithelium (RPE after trypan-blue-assisted peeling of internal limiting membrane (ILM for macular hole surgery. A 68-year-old Caucasian female underwent a 20-g pars plana vitrectomy for a chronic stage-3 macular hole. The ILM was stained with 0.06% trypan blue (VisionBlue™, DORC Netherlands for 2 min after fluid air exchange. Dye was reapplied for another 2 min due to poor staining. The ILM was completely removed around the macular hole with forceps. RPE atrophy was noticed at the edge of the hole 1 month after surgery. It progressively increased in intensity and enlarged over 2 years. Her final visual acuity was counting fingers, significantly worse compared to her presenting visual acuity of 20/200. Progressive atrophy of RPE in our patient was most likely due to the toxicity of trypan blue. Reapplication of the dye may increase the likelihood of toxicity.

  10. Eye lens membrane junctional microdomains: a comparison between healthy and pathological cases

    Energy Technology Data Exchange (ETDEWEB)

    Buzhynskyy, Nikolay; Scheuring, Simon [Institut Curie, Equipe Inserm Avenir, UMR168-CNRS, 26 Rue d' Ulm, 75248 Paris Cedex 05 (France); Sens, Pierre [ESPCI, CNRS-UMR 7083, 75231 Paris (France); Behar-Cohen, Francine, E-mail: simon.scheuring@curie.fr [UMRS Inserm 872, Universite Paris Descartes, Centre de Recherches des Cordeliers, 15 rue de l' Ecole de Medecine, 75270 Paris Cedex 06 (France)

    2011-08-15

    The eye lens is a transparent tissue constituted of tightly packed fiber cells. To maintain homeostasis and transparency of the lens, the circulation of water, ions and metabolites is required. Junctional microdomains connect the lens cells and ensure both tight cell-to-cell adhesion and intercellular flow of fluids through a microcirculation system. Here, we overview membrane morphology and tissue functional requirements of the mammalian lens. Atomic force microscopy (AFM) has opened up the possibility of visualizing the junctional microdomains at unprecedented submolecular resolution, revealing the supramolecular assembly of lens-specific aquaporin-0 (AQP0) and connexins (Cx). We compare the membrane protein assembly in healthy lenses with senile and diabetes-II cataract cases and novel data of the lens membranes from a congenital cataract. In the healthy case, AQP0s form characteristic square arrays confined by connexons. In the cases of senile and diabetes-II cataract patients, connexons were degraded, leading to malformation of AQP0 arrays and breakdown of the microcirculation system. In the congenital cataract, connexons are present, indicating probable non-membranous grounds for lens opacification. Further, we discuss the energetic aspects of the membrane organization in junctional microdomains. The AFM hence becomes a biomedical nano-imaging tool for the analysis of single-membrane protein supramolecular association in healthy and pathological membranes.

  11. Eye lens membrane junctional microdomains: a comparison between healthy and pathological cases

    Science.gov (United States)

    Buzhynskyy, Nikolay; Sens, Pierre; Behar-Cohen, Francine; Scheuring, Simon

    2011-08-01

    The eye lens is a transparent tissue constituted of tightly packed fiber cells. To maintain homeostasis and transparency of the lens, the circulation of water, ions and metabolites is required. Junctional microdomains connect the lens cells and ensure both tight cell-to-cell adhesion and intercellular flow of fluids through a microcirculation system. Here, we overview membrane morphology and tissue functional requirements of the mammalian lens. Atomic force microscopy (AFM) has opened up the possibility of visualizing the junctional microdomains at unprecedented submolecular resolution, revealing the supramolecular assembly of lens-specific aquaporin-0 (AQP0) and connexins (Cx). We compare the membrane protein assembly in healthy lenses with senile and diabetes-II cataract cases and novel data of the lens membranes from a congenital cataract. In the healthy case, AQP0s form characteristic square arrays confined by connexons. In the cases of senile and diabetes-II cataract patients, connexons were degraded, leading to malformation of AQP0 arrays and breakdown of the microcirculation system. In the congenital cataract, connexons are present, indicating probable non-membranous grounds for lens opacification. Further, we discuss the energetic aspects of the membrane organization in junctional microdomains. The AFM hence becomes a biomedical nano-imaging tool for the analysis of single-membrane protein supramolecular association in healthy and pathological membranes.

  12. Evolution of magnetic and transport properties in pore-modified CoAlO antidot arrays

    International Nuclear Information System (INIS)

    Ma, Y G; Lim, S L; Ong, C K

    2007-01-01

    CoAlO composite antidot arrays were fabricated on self-organized porous anodic aluminium oxide (AAO) membranes. The effects of pore size and film thickness on the magnetism and magnetotransport properties of the CoAlO films were investigated. On increasing the pore dimensions in the arrays, an anisotropic to isotropic magnetism transition was observed. The result is discussed based on the competitive contributions from the external field induced uniaxial anisotropy and the topology-induced shape anisotropy superimposed by the stray fields from the pore channels. Magnetoresistance showed corresponding variations with increasing pore sizes, as evidenced by a magnetoresistance variation from typically anisotropic to nearly isotropic behaviour. When deposited on large-pored AAO membranes, the antidot arrays showed no obvious anisotropy at different film thicknesses. It led to negligible magnetoresistive loops in the thick films of high structural continuity. The possible reasons for spin-independent electron scatterings are discussed

  13. Membrane architectures for ion-channel switch-based electrochemical biosensors

    Science.gov (United States)

    Sansinena, Jose-Maria; Redondo, Antonio; Swanson, Basil I.; Yee, Chanel Kitmon; Sapuri/Butti, Annapoorna R.; Parikh, Atul N.; Yang, Calvin

    2008-10-28

    The present invention is directed to a process of forming a bilayer lipid membrane structure by depositing an organic layer having a defined surface area onto an electrically conductive substrate, removing portions of said organic layer upon said electrically conductive substrate whereby selected portions of said organic layer are removed to form defined voids within said defined surface area of said organic layer and defined islands of organic layer upon said electrically conductive substrate, and, depositing a bilayer lipid membrane over the defined voids and defined islands of organic layer upon said substrate whereby aqueous reservoirs are formed between said electrically conductive substrate and said bilayer lipid membrane, said bilayer lipid membrane characterized as spanning across the defined voids between said defined islands. A lipid membrane structure is also described together with an array of such lipid membrane structure.

  14. Oriented Mn-doped CuO nanowire arrays

    International Nuclear Information System (INIS)

    Han, Dongqiang; Wu, Zhaofeng; Wang, Zhihe; Yang, Shaoguang

    2016-01-01

    Using anodic aluminum oxide membranes as the nanoreactors and controller, oriented nanowire arrays of the diluted magnetic semiconductor Mn-doped CuO have been successfully fabricated using Mn(NO_3)_2 · 4H_2O and Cu(NO_3)_2 · 3H_2O as the starting materials. X-ray diffraction measurements showed that the as-prepared oriented nanowire arrays are of high purity. Scanning electron microscope and transmission electron microscope studies showed the nanowires are oriented, continuous and uniform with a diameter and length of about 170 nm and several tens of micrometers, respectively, and thus of a high aspect ratio. Low-temperature magnetic measurements showed the ferromagnetic property of the oriented Mn-doped CuO nanowire arrays with the critical temperature at around 80 K, which will endow them with great potential applications in spintronics in the future. (paper)

  15. Electrochemical properties of proton exchange membranes: the role of composition and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Holdcroft, S.; Beattie, P.D.; Basura, V.I.; Schmeisser, J.; Chuy, C.; Orfino, F.; Ding, J. [Simon Fraser Univ., Burnaby, BC (Canada). Dept. of Chemistry

    2001-06-01

    To measure electrochemical and proton conduction properties of a large variety of different polyelectrolyte membranes that possess a wide array of equivalent weights and water contents, a number of analytical techniques were employed and the results presented in this paper. At the electrocatalyst/polymer electrolyte interface, kinetic and mass transport parameters play an important role in fuel cell operation, the authors used microelectrodes to study the effects of temperature and pressure on the electrochemical reduction of oxygen at platinum/solid polymer electrolyte interfaces in solid polymer electrolytes under controlled humidity. Under conditions of controlled humidity and temperature, proton conductivity was measured transverse and normal to the membrane surface using an alternate current (a.c.) impedance spectroscopy. A wide array of membranes were investigated, including those based on sulfonated polystyrene-block-hydrogenated butadiene, polystyrenesulfonic acid grafted onto ethylenetetrafluoroethylene, sulfonated trifluorostyrene-copolymers, and a novel series of membranes where the internal biphasic morphology is controlled to yield materials with low water and high conductivity and prepared in house. Transmission electron microscopy and small angle X-ray scattering was used for the analysis of the microstructure of selected membranes. Modelling the scattered intensities was used to quantify aspects of the microstructure.

  16. The Fabrication and Application of a PDMS Micro Through-Holes Mask in Electrochemical Micromanufacturing

    Directory of Open Access Journals (Sweden)

    Xiaolei Chen

    2014-08-01

    Full Text Available The electrochemical micromanufacturing process, as a key micromanufacturing technology, plays an important role in diverse industries. In this paper, polydimethylsiloxane (PDMS is employed as a mask in the electrochemical micromanufacture of microstructures because of its chemical resistance, low cost, flexibility, and high molding capability. A new method for fabricating a PDMS micro through-holes mask is proposed. In this method, a thin resist film is employed to enhance the adhesion between the substrate and the SU-8 pillar array which is used as a mold. A vacuum-aided process is used to inject the PDMS gel into the SU-8 mold and the PDMS micro through-holes mask can be peeled off from the SU-8 mold when the gel is cured. Experiments were conducted to verify the feasibility of the proposed approach and PDMS microholes of various shapes were obtained. The PDMS mask can then be successfully applied in the electrochemical micromanufacturing process to generate microstructures and microdimple and embossment arrays have been successfully demonstrated. Furthermore, the PDMS mask can be reused, as it is not damaged during the manufacturing process.

  17. Electron and hole spectrum in InAs quantum dot renormalized by InAs/GaAs heterostructure deformation

    International Nuclear Information System (INIS)

    Dan'kiv, O.O.; Peleshchak, R.M.

    2005-01-01

    Analytical expressions describing the energy spectrum of electrons and holes are obtained for a quantum dot occurring in a self-consistent strain field created by an array of coherently stressed quantum dots. A method of taking into account the lattice mismatch at the quantum dot-matrix interface is proposed that allows for the dependence of the mismatch parameter on the quantum dot size and the matrix layer thickness. It is shown that the internal elastic strain arising at the quantum dot-matrix interface influences the energy spectrum of electrons more significantly than the spectrum of holes [ru

  18. Hole dephasing caused by hole-hole interaction in a multilayered black phosphorus.

    Science.gov (United States)

    Li, Lijun; Khan, Muhammad Atif; Lee, Yoontae; Lee, Inyeal; Yun, Sun Jin; Youn, Doo-Hyeb; Kim, Gil-Ho

    2017-11-01

    We study the magnetotransport of holes in a multilayered black phosphorus in a temperature range of 1.9 to 21.5 K. We observed a negative magnetoresistance at magnetic fields up to 1.5 T. This negative magetoresistance was analyzed by weak localization theory in diffusive regime. At the lowest temperature and the highest carrier density we found a phase coherence length of 48 nm. The linear temperature dependence of the dephasing rate shows that the hole-hole scattering processes with small energy transfer are the dominant contribution in breaking the carrier phase coherence.

  19. Many-body dynamics of holes in a driven, dissipative spin chain of Rydberg superatoms

    Science.gov (United States)

    Letscher, Fabian; Petrosyan, David; Fleischhauer, Michael

    2017-11-01

    Strong, long-range interactions between atoms in high-lying Rydberg states can suppress multiple Rydberg excitations within a micron-sized trapping volume and yield sizable Rydberg level shifts at larger distances. Ensembles of atoms in optical microtraps then form Rydberg superatoms with collectively enhanced transition rates to the singly excited state. These superatoms can represent mesoscopic, strongly interacting spins. We study a regular array of such effective spins driven by a laser field tuned to compensate the interaction-induced level shifts between neighboring superatoms. During the initial transient, a few excited superatoms seed a cascade of resonantly facilitated excitation of large clusters of superatoms. Due to spontaneous decay, the system then relaxes to the steady state having nearly universal Rydberg excitation density {ρ }{{R}}=2/3. This state is characterized by highly non-trivial equilibrium dynamics of quasi-particles—excitation holes in the lattice of Rydberg excited superatoms. We derive an effective many-body model that accounts for hole mobility as well as continuous creation and annihilation of holes upon collisions with each other. We find that holes exhibit a nearly incompressible liquid phase with highly sub-Poissonian number statistics and finite-range density-density correlations.

  20. Three-dimensionally Functionalized Reverse Phase Glycoprotein Array for Cancer Biomarker Discovery and Validation

    OpenAIRE

    Pan, Li; Aguilar, Hillary Andaluz; Wang, Linna; Iliuk, Anton; Tao, W. Andy

    2016-01-01

    Glycoproteins have vast structural diversity which plays an important role in many biological processes and have great potential as disease biomarkers. Here we report a novel functionalized reverse phase protein array (RPPA), termed polymer-based reverse phase GlycoProtein Array (polyGPA), to specifically capture and profile glycoproteomes, and validate glycoproteins. Nitrocellulose membrane functionalized with globular hydroxyaminodendrimers was used to covalently capture pre-oxidized glycan...

  1. Bifurcation from stable holes to replicating holes in vibrated dense suspensions.

    Science.gov (United States)

    Ebata, H; Sano, M

    2013-11-01

    In vertically vibrated starch suspensions, we observe bifurcations from stable holes to replicating holes. Above a certain acceleration, finite-amplitude deformations of the vibrated surface continue to grow until void penetrates fluid layers, and a hole forms. We studied experimentally and theoretically the parameter dependence of the holes and their stabilities. In suspensions of small dispersed particles, the circular shapes of the holes are stable. However, we find that larger particles or lower surface tension of water destabilize the circular shapes; this indicates the importance of capillary forces acting on the dispersed particles. Around the critical acceleration for bifurcation, holes show intermittent large deformations as a precursor to hole replication. We applied a phenomenological model for deformable domains, which is used in reaction-diffusion systems. The model can explain the basic dynamics of the holes, such as intermittent behavior, probability distribution functions of deformation, and time intervals of replication. Results from the phenomenological model match the linear growth rate below criticality that was estimated from experimental data.

  2. Full Thickness Macular Hole Closure after Exchanging Silicone-Oil Tamponade with C3F8 without Posturing

    Directory of Open Access Journals (Sweden)

    Tina Xirou

    2011-05-01

    Full Text Available Purpose: To report a case of macular hole closure after the exchange of a silicone-oil tamponade with gas C3F8 14%. Method: A 64-year-old female patient with a stage IV macular hole underwent a three-port pars-plana vitrectomy and internal limiting membrane peeling. Due to the patient’s chronic illness (respiratory problems, a silicone-oil tamponade was preferred. However, the macula hole was still flat opened four months postoperatively. Therefore, the patient underwent an exchange of silicone oil with gas C3F8 14%. No face-down position was advised postoperatively due to her health problems. Results: Macular hole closure was confirmed with optical coherence tomography six weeks after exchanging the silicone oil with gas. Conclusions: Macular hole surgery using a silicone-oil tamponade has been proposed as treatment of choice for patients unable to posture. In our case, the use of a long-acting gas (C3F8 14%, even without posturing, proved to be more effective.

  3. Diagnosis of foetal membrane ruptures: Placental alpha ...

    African Journals Online (AJOL)

    Context: Pre‑labour rupture of membranes (PROM) is a common obstetric complication which presents a diagnostic challenge, especially in equivocal ... problematic with the need to balance the risk of prematurity with that of prolonged ... array of rapid, minimally invasive tests based on biochemical markers in amniotic fluid ...

  4. Hydrophilicity Reinforced Adhesion of Anodic Alumina Oxide Template Films to Conducting Substrates for Facile Fabrication of Highly Ordered Nanorod Arrays.

    Science.gov (United States)

    Wang, Chuanju; Wang, Guiqiang; Yang, Rui; Sun, Xiangyu; Ma, Hui; Sun, Shuqing

    2017-01-17

    Arrays of ordered nanorods are of special interest in many fields. However, it remains challenging to obtain such arrays on conducting substrates in a facile manner. In this article, we report the fabrication of highly ordered and vertically standing nanorod arrays of both metals and semiconductors on Au films and indium tin oxide glass substrates without an additional layering. In this approach, following the simple hydrophilic treatment of an anodic aluminum oxide (AAO) membrane and conducting substrates, the AAO membrane was transferred onto the modified substrates with excellent adhesion. Subsequently, nanorod arrays of various materials were electrodeposited on the conducting substrates directly. This method avoids any expensive and tedious lithographic and ion milling process, which provides a simple yet robust route to the fabrication of arrays of 1D materials with high aspect ratio on conducting substrates, which shall pave the way for many practical applications in a range of fields.

  5. Electrically driven light emission from an array of Si nanoclusters

    International Nuclear Information System (INIS)

    Mazzitello, K I; Martin, H O; Aldao, C M; Roman, H E

    2004-01-01

    Charge transport and light emission properties of an array of silicon nanoclusters (NCs), sandwiched between a p-type and an n-type doped silicon crystal, are studied theoretically by assuming that electrons and holes enter from the opposite sides of the array in response to an applied electric field. The size of the NCs considered ranges from 16 nm down to 3.6 nm and their spatial distribution is optimized so that light emission, resulting from radiative recombinations, is peaked in the visible red around 1.8 eV. The light emission efficiency is limited by the carrier hopping times and is found to be in the range 2-0.5%, for fields ranging from 100 kV cm -1 to 500 kV cm -1 , respectively

  6. Fabrication of polymeric nano-batteries array using anodic aluminum oxide templates.

    Science.gov (United States)

    Zhao, Qiang; Cui, Xiaoli; Chen, Ling; Liu, Ling; Sun, Zhenkun; Jiang, Zhiyu

    2009-02-01

    Rechargeable nano-batteries were fabricated in the array pores of anodic aluminum oxide (AAO) template, combining template method and electrochemical method. The battery consisted of electropolymerized PPy electrode, porous TiO2 separator, and chemically polymerized PAn electrode was fabricated in the array pores of two-step anodizing aluminum oxide (AAO) membrane, based on three-step assembling method. It performs typical electrochemical battery behavior with good charge-discharge ability, and presents a capacity of 25 nAs. AFM results show the hexagonal array of nano-batteries' top side. The nano-battery may be a promising device for the development of Micro-Electro-Mechanical Systems (MEMS), and Nano-Electro-Mechanical Systems (NEMS).

  7. Self-assembly and optical properties of patterned ZnO nanodot arrays

    International Nuclear Information System (INIS)

    Song Yijian; Zheng Maojun; Ma Li

    2007-01-01

    Patterned ZnO nanodot (ND) arrays and a ND-cavity microstructure were realized on an anodic alumina membrane (AAM) surface through a spin-coating sol-gel process, which benefits from the morphology and localized negative charge surface of AAM as well as the optimized sol concentration. The growth mechanism is believed to be a self-assembly process. This provides a simple approach to fabricate semiconductor quantum dot (QD) arrays and a QD-cavity system with its advantage in low cost and mass production. Strong ultra-violet emission, a multi-phonon process, and its special structure-related properties were observed in the patterned ZnO ND arrays

  8. Gold Nanohole Array with Sub-1 nm Roughness by Annealing for Sensitivity Enhancement of Extraordinary Optical Transmission Biosensor

    Science.gov (United States)

    Zhang, Jian; Irannejad, Mehrdad; Yavuz, Mustafa; Cui, Bo

    2015-05-01

    Nanofabrication technology plays an important role in the performance of surface plasmonic devices such as extraordinary optical transmission (EOT) sensor. In this work, a double liftoff process was developed to fabricate a series of nanohole arrays of a hole diameter between 150 and 235 nm and a period of 500 nm in a 100-nm-thick gold film on a silica substrate. To improve the surface quality of the gold film, thermal annealing was conducted, by which an ultra-smooth gold film with root-mean-square (RMS) roughness of sub-1 nm was achieved, accompanied with a hole diameter shrinkage. The surface sensitivity of the nanohole arrays was measured using a monolayer of 16-mercaptohexadecanoic acid (16-MHA) molecule, and the surface sensitivity was increased by 2.5 to 3 times upon annealing the extraordinary optical transmission (EOT) sensor.

  9. Intelligent Membranes: Dream or Reality?

    Directory of Open Access Journals (Sweden)

    Annarosa Gugliuzza

    2013-07-01

    Full Text Available Intelligent materials are claimed to overcome current drawbacks associated with the attainment of high standards of life, health, security and defense. Membrane-based sensors represent a category of smart systems capable of providing a large number of benefits to different markets of textiles, biomedicine, environment, chemistry, agriculture, architecture, transport and energy. Intelligent membranes can be characterized by superior sensitivity, broader dynamic range and highly sophisticated mechanisms of autorecovery. These prerogatives are regarded as the result of multi-compartment arrays, where complementary functions can be accommodated and well-integrated. Based on the mechanism of “sense to act”, stimuli-responsive membranes adapt themselves to surrounding environments, producing desired effects such as smart regulation of transport, wetting, transcription, hydrodynamics, separation, and chemical or energy conversion. Hopefully, the design of new smart devices easier to manufacture and assemble can be realized through the integration of sensing membranes with wireless networks, looking at the ambitious challenge to establish long-distance communications. Thus, the transfer of signals to collecting systems could allow continuous and real-time monitoring of data, events and/or processes.

  10. The development of a high-throughput measurement method of octanol/water distribution coefficient based on hollow fiber membrane solvent microextraction technique.

    Science.gov (United States)

    Bao, James J; Liu, Xiaojing; Zhang, Yong; Li, Youxin

    2014-09-15

    This paper describes the development of a novel high-throughput hollow fiber membrane solvent microextraction technique for the simultaneous measurement of the octanol/water distribution coefficient (logD) for organic compounds such as drugs. The method is based on a designed system, which consists of a 96-well plate modified with 96 hollow fiber membrane tubes and a matching lid with 96 center holes and 96 side holes distributing in 96 grids. Each center hole was glued with a sealed on one end hollow fiber membrane tube, which is used to separate the aqueous phase from the octanol phase. A needle, such as microsyringe or automatic sampler, can be directly inserted into the membrane tube to deposit octanol as the accepted phase or take out the mixture of the octanol and the drug. Each side hole is filled with aqueous phase and could freely take in/out solvent as the donor phase from the outside of the hollow fiber membranes. The logD can be calculated by measuring the drug concentration in each phase after extraction equilibrium. After a comprehensive comparison, the polytetrafluoroethylene hollow fiber with the thickness of 210 μm, an extraction time of 300 min, a temperature of 25 °C and atmospheric pressure without stirring are selected for the high throughput measurement. The correlation coefficient of the linear fit of the logD values of five drugs determined by our system to reference values is 0.9954, showed a nice accurate. The -8.9% intra-day and -4.4% inter-day precision of logD for metronidazole indicates a good precision. In addition, the logD values of eight drugs were simultaneously and successfully measured, which indicated that the 96 throughput measure method of logD value was accurate, precise, reliable and useful for high throughput screening. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. A Time Modulated Printed Dipole Antenna Array for Beam Steering Application

    Directory of Open Access Journals (Sweden)

    Ruchi Gahley

    2017-01-01

    Full Text Available This paper presents time modulated beam steered antenna array without phase shifters. The beam steering is analyzed considering a two-element time modulated antenna array (TMAA of printed dipoles with microstrip via-hole balun. The proposed array resonates at the Industrial, Scientific, and Medical (ISM radio bands, 2.45 GHz and 5.8 GHz, and offers wide bandwidth inherited due to modified structure of ground plane. Array elements are excited by complex exponential excitation signal through broadband power divider and radio frequency (RF switches to achieve amplitude and phase variation without phase shifters. Differential Evolution algorithm is used to modify the time sequences of the RF switches connected to the antennas to generate radiation pattern with optimum dynamic efficiency by suppressing sideband radiations. Also switch-on time instant of RF switch connected to the subsequent element is modulated to steer the beam towards different directions. The proposed prototype is fabricated followed by parametric optimization. The fabrication results agree significantly well with simulated results.

  12. Protein diffusion in plant cell plasma membranes: The cell-wall corral

    Directory of Open Access Journals (Sweden)

    Alexandre eMartinière

    2013-12-01

    Full Text Available Studying protein diffusion informs us about how proteins interact with their environment. Work on protein diffusion over the last several decades has illustrated the complex nature of biological lipid bilayers. The plasma membrane contains an array of membrane-spanning proteins or proteins with peripheral membrane associations. Maintenance of plasma membrane microstructure can be via physical features that provide intrinsic ordering such as lipid microdomains, or from membrane-associated structures such as the cytoskeleton. Recent evidence indicates, that in the case of plant cells, the cell wall seems to be a major player in maintaining plasma membrane microstructure. This interconnection / interaction between cell-wall and plasma membrane proteins most likely plays an important role in signal transduction, cell growth, and cell physiological responses to the environment.

  13. Etching holes in graphene supercapacitor electrodes for faster performance.

    Science.gov (United States)

    Ervin, Matthew H

    2015-06-12

    Graphene is being widely investigated as a material to replace activated carbon in supercapacitor (electrochemical capacitor) electrodes. Supercapacitors have much higher energy density, but are typically slow devices (∼0.1 Hz) compared to other types of capacitors. Here, top-down semiconductor processing has been applied to graphene-based electrodes in order to fabricate ordered arrays of holes through the graphene electrodes. This is demonstrated to increase the speed of the electrodes by reducing the ionic impedance through the electrode thickness. This approach may also be applicable to speeding up other types of devices, such as batteries and sensors, that use porous electrodes.

  14. Solar array experiments on the SPHINX satellite. [Space Plasma High voltage INteraction eXperiment satellite

    Science.gov (United States)

    Stevens, N. J.

    1974-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations: the edge illuminated-multijunction cells, the teflon encased cells, and the violet cells.

  15. Analysis of a new unidimensional model and lateral vibrations of 1-3 piezocomposite side scan sonar array

    CSIR Research Space (South Africa)

    Shatalov, MY

    2006-01-01

    Full Text Available . Lamb modes of the 1-3 piezocomposites are investigated in term of the Certon-Patat membrane model by means of direct variational method application. A new design of a 1-3 piezocomposite side scan SONAR array is considered. An implementation of the array...

  16. Nucleation of holin domains and holes optimizes lysis timing of E. coli by phage λ

    Science.gov (United States)

    Ryan, Gillian; Rutenberg, Andrew

    2007-03-01

    Holin proteins regulate the precise scheduling of Escherichia coli lysis during infection by bacteriophage λ. Inserted into the host bacterium's inner membrane during infection, holins aggregate to form rafts and then holes within those rafts. We present a two-stage nucleation model of holin action, with the nucleation of condensed holin domains followed by the nucleation of holes within these domains. Late nucleation of holin rafts leads to a weak dependence of lysis timing on host cell size, though both nucleation events contribute equally to timing errors. Our simulations recover the accurate scheduling observed experimentally, and also suggest that phage-λ lysis of E.coli is optimized.

  17. Electrostatically Driven Assembly of Charged Amphiphiles Forming Crystallized Membranes, Vesicles and Nanofiber Arrays

    Science.gov (United States)

    Leung, Cheuk Yui Curtis

    Charged amphiphilic molecules can self-assemble into a large variety of objects including membranes, vesicles and fibers. These micro to nano-scale structures have been drawing increasing attention due to their broad applications, especially in biotechnology and biomedicine. In this dissertation, three self-assembled systems were investigated: +3/-1 self-assembled catanionic membranes, +2/-1 self-assembled catanionic membranes and +1 self-assembled nanofibers. Transmission electron microscopy (TEM) combined with synchrotron small and wide angle x-ray scattering (SAXS and WAXS) were used to characterize the coassembled structures from the mesoscopic to nanometer scale. We designed a system of +3 and -1 ionic amphiphiles that coassemble into crystalline ionic bilayer vesicles with large variety of geometries that resemble polyhedral cellular crystalline shells and archaea wall envelopes. The degree of ionization of the amphiphiles and their intermolecular electrostatic interactions can be controlled by varying pH. The molecular packing of these membranes showed a hexagonal to rectangular-C to hexagonal phase transition with increasing pH, resulting in significant changes to the membrane morphology. A similar mixture of +2 and -1 ionic amphiphiles was also investigated. In addition to varying pH, which controls the headgroup attractions, we also adjust the tail length of the amphiphiles to control the van der Waals interactions between the tails. A 2D phase diagram was developed to show how pH and tail length can be used to control the intermolecular packing within the membranes. Another system of self-assembled nanofiber network formed by positively charged amphiphiles was also studied. These highly charged fibers repel each other and are packed in hexagonal lattice with lattice constant at least eight times of the fiber diameter. The d-spacing and the crystal structure can be controlled by varying the solution concentration and temperature.

  18. Black Holes

    OpenAIRE

    Horowitz, Gary T.; Teukolsky, Saul A.

    1998-01-01

    Black holes are among the most intriguing objects in modern physics. Their influence ranges from powering quasars and other active galactic nuclei, to providing key insights into quantum gravity. We review the observational evidence for black holes, and briefly discuss some of their properties. We also describe some recent developments involving cosmic censorship and the statistical origin of black hole entropy.

  19. Non-lithographic method of forming ordered arrays of silicon pillars and macropores

    International Nuclear Information System (INIS)

    Mills, David; Kolasinski, Kurt W

    2005-01-01

    Micrometre-scale Si pillars are formed by chemically enhanced laser ablation using nanosecond excimer laser irradiation of a Si single crystal in the presence of SF 6 . We demonstrate the importance of precursor holes in determining the positioning of the pillars and show that we can control the initiation of precursor holes by ruling a grating into the Si substrate prior to irradiation. A rule defines an edge from which the laser light diffracts. Near-field amplification of the laser intensity enhances the formation of the precursor holes and aligns them parallel to the rule. The pillars can be thinned and eventually removed by wet chemical etching in aqueous KOH, resulting first in ordered arrays of extremely high aspect ratio pillars (e.g. tens of micrometres in length, with ∼ 10 nm tips) and then macropores. The shape of the macropore is determined by crystallography and the anisotropy of the wet etchant

  20. Black hole levitron

    International Nuclear Information System (INIS)

    Arsiwalla, Xerxes D.; Verlinde, Erik P.

    2010-01-01

    We study the problem of spatially stabilizing four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes placed in external fields we find that taking a continuum limit of Denef et al.'s multicenter supersymmetric black hole solutions provides a supergravity description of such backgrounds within which a black hole can be trapped within a confined volume. This construction is realized by solving for a levitating black hole over a magnetic dipole base. We comment on how such a construction is akin to a mechanical levitron.

  1. Wire Array Solar Cells: Fabrication and Photoelectrochemical Studies

    Science.gov (United States)

    Spurgeon, Joshua Michael

    Despite demand for clean energy to reduce our addiction to fossil fuels, the price of these technologies relative to oil and coal has prevented their widespread implementation. Solar energy has enormous potential as a carbon-free resource but is several times the cost of coal-produced electricity, largely because photovoltaics of practical efficiency require high-quality, pure semiconductor materials. To produce current in a planar junction solar cell, an electron or hole generated deep within the material must travel all the way to the junction without recombining. Radial junction, wire array solar cells, however, have the potential to decouple the directions of light absorption and charge-carrier collection so that a semiconductor with a minority-carrier diffusion length shorter than its absorption depth (i.e., a lower quality, potentially cheaper material) can effectively produce current. The axial dimension of the wires is long enough for sufficient optical absorption while the charge-carriers are collected along the shorter radial dimension in a massively parallel array. This thesis explores the wire array solar cell design by developing potentially low-cost fabrication methods and investigating the energy-conversion properties of the arrays in photoelectrochemical cells. The concept was initially investigated with Cd(Se, Te) rod arrays; however, Si was the primary focus of wire array research because its semiconductor properties make low-quality Si an ideal candidate for improvement in a radial geometry. Fabrication routes for Si wire arrays were explored, including the vapor-liquid-solid growth of wires using SiCl4. Uniform, vertically aligned Si wires were demonstrated in a process that permits control of the wire radius, length, and spacing. A technique was developed to transfer these wire arrays into a low-cost, flexible polymer film, and grow multiple subsequent arrays using a single Si(111) substrate. Photoelectrochemical measurements on Si wire array

  2. Visible-light-driven photoelectrochemical and photocatalytic performances of Cr-doped SrTiO3/TiO2 heterostructured nanotube arrays.

    Science.gov (United States)

    Jiao, Zhengbo; Chen, Tao; Xiong, Jinyan; Wang, Teng; Lu, Gongxuan; Ye, Jinhua; Bi, Yingpu

    2013-01-01

    Well-aligned TiO2 nanotube arrays have become of increasing significance because of their unique highly ordered array structure, high specific surface area, unidirectional charge transfer and transportation features. However, their poor visible light utilization as well as the high recombination rate of photoexcited electron-hole pairs greatly limited their practical applications. Herein, we demonstrate the fabrication of visible-light-responsive heterostructured Cr-doped SrTiO3/TiO2 nanotube arrays by a simple hydrothermal method, which facilitate efficient charge separation and thus improve the photoelectrochemical as well as photocatalytic performances.

  3. Towards Development of Microcalorimeter Arrays of Mo/Au Transition-Edge Sensors with Bismuth Absorbers

    Science.gov (United States)

    Tralshawala, Nilesh; Brekosky, Regis; Figueroa-Feliciano, Enectali; Li, Mary; Stahle, Carl; Stahle, Caroline

    2000-01-01

    We report on our progress towards the development of arrays of X-ray microcalorimeters as candidates for the high resolution x-ray spectrometer on the Constellation-X mission. The microcalorimeter arrays (30 x 30) with appropriate pixel sizes (0.25 mm. x 0.25 mm) and high packing fractions (greater than 96%) are being developed. Each individual pixel has a 10 micron thick Bi X-ray absorber that is shaped like a mushroom to increase the packing fraction, and a Mo/Au proximity effect superconducting transition edge sensor (TES). These are deposited on a 0.25 or 0.5 micron thick silicon nitride membrane with slits to provide a controllable weak thermal link to the sink temperature. Studies are underway to model, test and optimize the TES pixel uniformity, critical current, heat capacity and the membrane thermal conductance in the array structure. Fabrication issues and procedures, and results of our efforts based on these optimizations will be provided.

  4. Noncommutative black holes

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-DomInguez, J C [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); Obregon, O [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); RamIrez, C [Facultad de Ciencias FIsico Matematicas, Universidad Autonoma de Puebla, PO Box 1364, 72000 Puebla (Mexico); Sabido, M [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico)

    2007-11-15

    We study noncommutative black holes, by using a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Through the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular, we calculate Hawking's temperature and entropy for the 'noncommutative' Schwarzschild black hole.

  5. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    large values of Ф, black holes do form and for small values the scalar field ... on the near side of the ridge ultimately evolve to form black holes while those configu- ... The inset shows a bird's eye view looking down on the saddle point.

  6. Search for black holes

    International Nuclear Information System (INIS)

    Cherepashchuk, Anatolii M

    2003-01-01

    Methods and results of searching for stellar mass black holes in binary systems and for supermassive black holes in galactic nuclei of different types are described. As of now (June 2002), a total of 100 black hole candidates are known. All the necessary conditions Einstein's General Relativity imposes on the observational properties of black holes are satisfied for candidate objects available, thus further assuring the existence of black holes in the Universe. Prospects for obtaining sufficient criteria for reliably distinguishing candidate black holes from real black holes are discussed. (reviews of topical problems)

  7. NuSTAR and SWIFT Observations of the Black Hole Candidate XTE J1908+094 during its 2013 Outburst

    DEFF Research Database (Denmark)

    Tao, Lian; Tomsick, John A.; Walton, Dominic J.

    2015-01-01

    The black hole (BH) candidate XTE J1908+094 went into outburst for the first time since 2003 in 2013 October. We report on an observation with the Nuclear Spectroscopic Telescope Array (NuSTAR) and monitoring observations with Swift during the outburst. NuSTAR caught the source in the soft state...

  8. Enhanced lifetime for thin-dielectric microdischarge-arrays operating in DC

    Science.gov (United States)

    Dussart, Remi; Felix, Valentin; Overzet, Lawrence; Aubry, Olivier; Stolz, Arnaud; Lefaucheux, Philippe; Gremi-Univ Orleans-Cnrs Collaboration; University Of Texas At Dallas Collaboration

    2016-09-01

    Micro-hollow cathode discharge arrays using silicon as the cathode have a very limited lifetime because the silicon bubbles and initiates micro-arcing. To avoid this destructive behavior, the same configuration was kept but, another material was selected for the cathode. Using micro and nanotechnologies ordinarily used in microelectronic and MEMS device fabrication, we made arrays of cathode boundary layer (CBL)-type microreactors consisting of nickel electrodes separated by a 6 µm thick SiO2 layer. Microdischarges were ignited in arrays of 100 µm diameter holes at different pressures (200750 Torr) in different gases. Electrical and optical measurements were made to characterize the arrays. Unlike the microdischarges produced using silicon cathodes, the Ni cathode discharges remain very stable with essentially no micro-arcing. DC currents between 50 and 900 µA flowed through each microreactor with a discharge voltage of typically 200 V. Stable V-I characteristics showing both the normal and abnormal regimes were observed and are consistent with the spread of the plasma over the cathode area. Due to their stability and lifetime, new applications of these DC, CBL-type microreactors can now be envisaged.

  9. Antifouling Ultrafiltration Membranes via Post-Fabrication Grafting of Biocidal Nanomaterials

    KAUST Repository

    Mauter, Meagan S.; Wang, Yue; Okemgbo, Kaetochi C.; Osuji, Chinedum O.; Giannelis, Emmanuel P.; Elimelech, Menachem

    2011-01-01

    Figure Presented: Ultrafiltration (UF) membranes perform critical pre-treatment functions in advanced water treatment processes. In operational systems, however, biofouling decreases membrane performance and increases the frequency and cost of chemical cleaning. The present work demonstrates a novel technique for covalently or ionically tethering antimicrobial nanoparticles to the surface of UF membranes. Silver nanoparticles (AgNPs) encapsulated in positively charged polyethyleneimine (PEI) were reacted with an oxygen plasma modified polysulfone UF membrane with and without 1-ethyl-3-(3- dimethylaminopropyl) carbodiimide hydrochloride (EDC) present. The nucleophilic primary amines of the PEI react with the electrophilic carboxyl groups on the UF membrane surface to form electrostatic and covalent bonds. The irreversible modification process imparts significant antimicrobial activity to the membrane surface. Post-synthesis functionalization methods, such as the one presented here, maximize the density of nanomaterials at the membrane surface and may provide a more efficient route for fabricating diverse array of reactive nanocomposite membranes. © 2011 American Chemical Society.

  10. Antifouling Ultrafiltration Membranes via Post-Fabrication Grafting of Biocidal Nanomaterials

    KAUST Repository

    Mauter, Meagan S.

    2011-08-24

    Figure Presented: Ultrafiltration (UF) membranes perform critical pre-treatment functions in advanced water treatment processes. In operational systems, however, biofouling decreases membrane performance and increases the frequency and cost of chemical cleaning. The present work demonstrates a novel technique for covalently or ionically tethering antimicrobial nanoparticles to the surface of UF membranes. Silver nanoparticles (AgNPs) encapsulated in positively charged polyethyleneimine (PEI) were reacted with an oxygen plasma modified polysulfone UF membrane with and without 1-ethyl-3-(3- dimethylaminopropyl) carbodiimide hydrochloride (EDC) present. The nucleophilic primary amines of the PEI react with the electrophilic carboxyl groups on the UF membrane surface to form electrostatic and covalent bonds. The irreversible modification process imparts significant antimicrobial activity to the membrane surface. Post-synthesis functionalization methods, such as the one presented here, maximize the density of nanomaterials at the membrane surface and may provide a more efficient route for fabricating diverse array of reactive nanocomposite membranes. © 2011 American Chemical Society.

  11. EVIDENCE FROM THE VERY LONG BASELINE ARRAY THAT J1502SE/SW ARE DOUBLE HOTSPOTS, NOT A SUPERMASSIVE BINARY BLACK HOLE

    International Nuclear Information System (INIS)

    Wrobel, J. M.; Walker, R. C.; Fu, H.

    2014-01-01

    SDSS J150243.09+111557.3 is a merging system at z = 0.39 that hosts two confirmed active galactic nuclei (AGNs), one unobscured and one dust-obscured, offset by several kiloparsecs. Deane et al. recently reported evidence from the European VLBI Network (EVN) that the dust-obscured AGN exhibits two flat-spectrum radio sources, J1502SE/SW, offset by 26 mas (140 pc), with each source being energized by its own supermassive black hole (BH). This intriguing interpretation of a close binary BH was reached after ruling out a double-hotspot scenario, wherein both hotspots are energized by a single, central BH, a configuration occurring in the well-studied compact symmetric objects. When observed with sufficient sensitivity and resolution, an object with double hotspots should have an edge-brightened structure. We report evidence from the Very Long Baseline Array (VLBA) for just such a structure in an image of the obscured AGN with higher sensitivity and resolution than the EVN images. We thus conclude that a double-hotspot scenario should be reconsidered as a viable interpretation for J1502SE/SW, and suggest further VLBA tests of that scenario. A double-hotspot scenario could have broad implications for feedback in obscured AGNs. We also report a VLBA detection of high-brightness-temperature emission from the unobscured AGN that is offset several kiloparsecs from J1502SE/SW

  12. Comparisons of foveal thickness and slope after macular hole surgery with and without internal limiting membrane peeling.

    Science.gov (United States)

    Ohta, Kouichi; Sato, Atsuko; Senda, Nami; Fukui, Emi

    2018-01-01

    We have shown that the foveal contour was asymmetrical after idiopathic macular hole (MH) closure by pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling. The purpose of this study was to determine whether these morphological changes differ in eyes after PPV without ILM peeling. Ten eyes of 10 patients that underwent PPV without ILM peeling and 12 eyes of 11 patients with ILM peeling were studied. The MH in all eyes was 6 months after the surgery. The mean parafoveal retinal thickness in the non-peeled group was 367.1 µm in the nasal (N), 353.0 µm in the temporal (T), 366.9 µm in the superior (S), and 357.3 µm in the inferior (I) sectors. The T, S, and I sectors were significantly thicker than the corresponding sectors in the ILM peeled group ( p =0.0008, 0.003, and 0.03, respectively). The mean ganglion cell complex was thicker not only in the N sector but also in the T sector in the non-peeled group. The mean retinal slopes in the non-peeled group (N, 40.2°; T, 37.6°; S, 41.2°; I, 39.5°) were flatter than those in the peeled group (N, 52.3°; T, 43.6°; S, 50.8°; I, 51.9°; p =0.009, 0.09, 0.008, and 0.017, respectively). The symmetrical fovea after MH surgery in the non-ILM peeled eyes indicates that the asymmetrical fovea after ILM peeling was probably due to the ILM peeling.

  13. A Dancing Black Hole

    Science.gov (United States)

    Shoemaker, Deirdre; Smith, Kenneth; Schnetter, Erik; Fiske, David; Laguna, Pablo; Pullin, Jorge

    2002-04-01

    Recently, stationary black holes have been successfully simulated for up to times of approximately 600-1000M, where M is the mass of the black hole. Considering that the expected burst of gravitational radiation from a binary black hole merger would last approximately 200-500M, black hole codes are approaching the point where simulations of mergers may be feasible. We will present two types of simulations of single black holes obtained with a code based on the Baumgarte-Shapiro-Shibata-Nakamura formulation of the Einstein evolution equations. One type of simulations addresses the stability properties of stationary black hole evolutions. The second type of simulations demonstrates the ability of our code to move a black hole through the computational domain. This is accomplished by shifting the stationary black hole solution to a coordinate system in which the location of the black hole is time dependent.

  14. XFEM Modelling of Multi-holes Plate with Single-row and Staggered Holes Configurations

    Directory of Open Access Journals (Sweden)

    Supar Khairi

    2017-01-01

    Full Text Available Joint efficiency is the key to composite structures assembly design, good structures response is dependent upon multi-holes behavior as subjected to remote loading. Current benchmarking work were following experimental testing series taken from literature on multi-holes problem. Eleven multi-hole configurations were investigated with various pitch and gage distance of staggered holes and non-staggered holes (single-row holes. Various failure modes were exhibited, most staggered holes demonstrates staggered crack path but non-staggered holes series displayed crack path along net-section plane. Stress distribution were carried out and good agreement were exhibited in experimental observation as reported in the respective literature. Consequently, strength prediction work were carried out under quasi-static loading, most showed discrepancy between 8% -31%, better prediction were exhibited in thicker and non-staggered holes plate combinations.

  15. Frequency-domain imaging algorithm for ultrasonic testing by application of matrix phased arrays

    Directory of Open Access Journals (Sweden)

    Dolmatov Dmitry

    2017-01-01

    Full Text Available Constantly increasing demand for high-performance materials and systems in aerospace industry requires advanced methods of nondestructive testing. One of the most promising methods is ultrasonic imaging by using matrix phased arrays. This technique allows to create three-dimensional ultrasonic imaging with high lateral resolution. Further progress in matrix phased array ultrasonic testing is determined by the development of fast imaging algorithms. In this article imaging algorithm based on frequency domain calculations is proposed. This approach is computationally efficient in comparison with time domain algorithms. Performance of the proposed algorithm was tested via computer simulations for planar specimen with flat bottom holes.

  16. Babinet's principle and the band structure of surface waves on patterned metal arrays

    Science.gov (United States)

    Edmunds, J. D.; Taylor, M. C.; Hibbins, A. P.; Sambles, J. R.; Youngs, I. J.

    2010-05-01

    The microwave response of an array of square metal patches and its complementary structure, an array of square holes, has been experimentally studied. The resonant phenomena, which yield either enhanced transmission or reflection, are attributed to the excitation of diffractively coupled surface waves. The band structure of these surface modes has been quantified for both p-(transverse magnetic) and s-(transverse electric) polarized radiation and is found to be dependent on the periodicity of the electric and magnetic fields on resonance. The results are in excellent accord with predictions from finite element method modeling and the electromagnetic form of Babinet's principle [Babinet, C. R. Acad. Sci. 4, 638 (1837)].

  17. Babinet's principle and the band structure of surface waves on patterned metal arrays

    International Nuclear Information System (INIS)

    Edmunds, J. D.; Taylor, M. C.; Hibbins, A. P.; Sambles, J. R.; Youngs, I. J.

    2010-01-01

    The microwave response of an array of square metal patches and its complementary structure, an array of square holes, has been experimentally studied. The resonant phenomena, which yield either enhanced transmission or reflection, are attributed to the excitation of diffractively coupled surface waves. The band structure of these surface modes has been quantified for both p-(transverse magnetic) and s-(transverse electric) polarized radiation and is found to be dependent on the periodicity of the electric and magnetic fields on resonance. The results are in excellent accord with predictions from finite element method modeling and the electromagnetic form of Babinet's principle [Babinet, C. R. Acad. Sci. 4, 638 (1837)].

  18. Black holes will break up solitons and white holes may destroy them

    International Nuclear Information System (INIS)

    Akbar, Fiki T.; Gunara, Bobby E.; Susanto, Hadi

    2017-01-01

    Highlights: • What happens if a soliton collides with a black or white hole? • Solitons can pass through black hole horizons, but they will break up into several solitons after the collision. • In the interaction with a white hole horizon, solitons either pass through the horizon or will be destroyed by it. - Abstract: We consider a quantum analogue of black holes and white holes using Bose–Einstein condensates. The model is described by the nonlinear Schrödinger equation with a ‘stream flow’ potential, that induces a spatial translation to standing waves. We then mainly consider the dynamics of dark solitons in a black hole or white hole flow analogue and their interactions with the event horizon. A reduced equation describing the position of the dark solitons was obtained using variational method. Through numerical computations and comparisons with the analytical approximation we show that solitons can pass through black hole horizons even though they will break up into several solitons after the collision. In the interaction with a white hole horizon, we show that solitons either pass through the horizon or will be destroyed by it.

  19. Black holes will break up solitons and white holes may destroy them

    Energy Technology Data Exchange (ETDEWEB)

    Akbar, Fiki T., E-mail: ftakbar@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10, Bandung, 40132 (Indonesia); Gunara, Bobby E., E-mail: bobby@fi.itb.ac.id [Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha no. 10, Bandung, 40132 (Indonesia); Susanto, Hadi, E-mail: hsusanto@essex.ac.uk [Department of Mathematical Sciences, University of Essex, Colchester, CO4 3SQ (United Kingdom)

    2017-06-15

    Highlights: • What happens if a soliton collides with a black or white hole? • Solitons can pass through black hole horizons, but they will break up into several solitons after the collision. • In the interaction with a white hole horizon, solitons either pass through the horizon or will be destroyed by it. - Abstract: We consider a quantum analogue of black holes and white holes using Bose–Einstein condensates. The model is described by the nonlinear Schrödinger equation with a ‘stream flow’ potential, that induces a spatial translation to standing waves. We then mainly consider the dynamics of dark solitons in a black hole or white hole flow analogue and their interactions with the event horizon. A reduced equation describing the position of the dark solitons was obtained using variational method. Through numerical computations and comparisons with the analytical approximation we show that solitons can pass through black hole horizons even though they will break up into several solitons after the collision. In the interaction with a white hole horizon, we show that solitons either pass through the horizon or will be destroyed by it.

  20. Caged black holes: Black holes in compactified spacetimes. I. Theory

    International Nuclear Information System (INIS)

    Kol, Barak; Sorkin, Evgeny; Piran, Tsvi

    2004-01-01

    In backgrounds with compact dimensions there may exist several phases of black objects including a black hole and a black string. The phase transition between them raises questions and touches on fundamental issues such as topology change, uniqueness, and cosmic censorship. No analytic solution is known for the black hole, and moreover one can expect approximate solutions only for very small black holes, while phase transition physics happens when the black hole is large. Hence we turn to numerical solutions. Here some theoretical background to the numerical analysis is given, while the results will appear in a subsequent paper. The goals for a numerical analysis are set. The scalar charge and tension along the compact dimension are defined and used as improved order parameters which put both the black hole and the black string at finite values on the phase diagram. The predictions for small black holes are presented. The differential and the integrated forms of the first law are derived, and the latter (Smarr's formula) can be used to estimate the 'overall numerical error'. Field asymptotics and expressions for physical quantities in terms of the numerical values are supplied. The techniques include the 'method of equivalent charges', free energy, dimensional reduction, and analytic perturbation for small black holes

  1. Alternate Explosions: Collapse and Accretion Events with Red Holes instead of Black Holes

    OpenAIRE

    Graber, James S.

    1999-01-01

    A red hole is "just like a black hole" except it lacks an event horizon and a singularity. As a result, a red hole emits much more energy than a black hole during a collapse or accretion event. We consider how a red hole solution can solve the "energy crisis" and power extremely energetic gamma ray bursts and hypernovae.

  2. Black and white holes

    International Nuclear Information System (INIS)

    Zeldovich, Ya.; Novikov, I.; Starobinskij, A.

    1978-01-01

    The theory is explained of the origination of white holes as a dual phenomenon with regard to the formation of black holes. Theoretically it is possible to derive the white hole by changing the sign of time in solving the general theory of relativity equation implying the black hole. The white hole represents the amount of particles formed in the vicinity of a singularity. For a distant observer, matter composed of these particles expands and the outer boundaries of this matter approach from the inside the gravitational radius Rsub(r). At t>>Rsub(r)/c all radiation or expulsion of matter terminates. For the outside observer the white hole exists for an unlimited length of time. In fact, however, it acquires the properties of a black hole and all processes in it cease. The qualitative difference between a white hole and a black hole is in that a white hole is formed as the result of an inner quantum explosion from the singularity to the gravitational radius and not as the result of a gravitational collapse, i.e., the shrinkage of diluted matter towards the gravitational radius. (J.B.)

  3. Black and white holes

    Energy Technology Data Exchange (ETDEWEB)

    Zeldovich, Ya; Novikov, I; Starobinskii, A

    1978-07-01

    The theory is explained of the origination of white holes as a dual phenomenon with regard to the formation of black holes. Theoretically it is possible to derive the white hole by changing the sign of time in solving the general theory of relativity equation implying the black hole. The white hole represents the amount of particles formed in the vicinity of a singularity. For a distant observer, matter composed of these particles expands and the outer boundaries of this matter approach from the inside the gravitational radius R/sub r/. At t>>R/sub r//c all radiation or expulsion of matter terminates. For the outside observer the white hole exists for an unlimited length of time. In fact, however, it acquires the properties of a black hole and all processes in it cease. The qualitative difference between a white hole and a black hole is in that a white hole is formed as the result of an inner quantum explosion from the singularity to the gravitational radius and not as the result of a gravitational collapse, i.e., the shrinkage of diluted matter towards the gravitational radius.

  4. Atomic force microscopy on plasma membranes from Xenopus laevis oocytes containing human aquaporin 4.

    Science.gov (United States)

    Orsini, Francesco; Santacroce, Massimo; Cremona, Andrea; Gosvami, Nitya N; Lascialfari, Alessandro; Hoogenboom, Bart W

    2014-11-01

    Atomic force microscopy (AFM) is a unique tool for imaging membrane proteins in near-native environment (embedded in a membrane and in buffer solution) at ~1 nm spatial resolution. It has been most successful on membrane proteins reconstituted in 2D crystals and on some specialized and densely packed native membranes. Here, we report on AFM imaging of purified plasma membranes from Xenopus laevis oocytes, a commonly used system for the heterologous expression of membrane proteins. Isoform M23 of human aquaporin 4 (AQP4-M23) was expressed in the X. laevis oocytes following their injection with AQP4-M23 cRNA. AQP4-M23 expression and incorporation in the plasma membrane were confirmed by the changes in oocyte volume in response to applied osmotic gradients. Oocyte plasma membranes were then purified by ultracentrifugation on a discontinuous sucrose gradient, and the presence of AQP4-M23 proteins in the purified membranes was established by Western blotting analysis. Compared with membranes without over-expressed AQP4-M23, the membranes from AQP4-M23 cRNA injected oocytes showed clusters of structures with lateral size of about 10 nm in the AFM topography images, with a tendency to a fourfold symmetry as may be expected for higher-order arrays of AQP4-M23. In addition, but only infrequently, AQP4-M23 tetramers could be resolved in 2D arrays on top of the plasma membrane, in good quantitative agreement with transmission electron microscopy analysis and the current model of AQP4. Our results show the potential and the difficulties of AFM studies on cloned membrane proteins in native eukaryotic membranes. Copyright © 2014 John Wiley & Sons, Ltd.

  5. Short-Acting Gas Tamponade with Strict Face-Down Posturing for the Treatment of Idiopathic Macular Hole.

    Science.gov (United States)

    Gotzaridis, Stratos; Liazos, Efstathios; Petrou, Petros; Georgalas, Ilias

    2017-01-01

    A retrospective consecutive case series to evaluate the safety and efficacy of 25 gauge pars plana vitrectomy, ILM peeling, 20% SF 6 gas tamponade and strict posturing for the treatment of idiopathic full-thickness macular holes. We report the results of 106 consecutive eyes that underwent standard 25-gauge pars plana vitrectomy, brilliant peel-assisted internal limiting membrane peel, fluid:gas exchange with 20% SF 6 and strict posturing for one week. All patients were followed up at one week, one month, three months, and nine months postoperatively. Biomicroscopy at day 1 and biomicroscopy and OCT at week 1, months 1, 3, and 9 were used to assess macular hole status postoperatively. Pre- and postoperative logMAR visual acuity was compared. The macular hole was closed in 102/106 eyes postoperatively (96.2%). Four eyes showed unclosed macular holes and underwent additional SF 6 intravitreal injection and strict posturing for 10 days. All macular holes were eventually closed without the need of a second surgical procedure. Mean visual acuity improved from 0.63 logMAR preoperatively to 0.39 logMAR postoperatively. One case of retinal toxicity was reported due to accidental intravitreal injection of antibiotic. 25-gauge vitrectomy, ILM peel, and short-acting gas tamponade are highly effective for the treatment of macular holes. Additional intravitreal gas injection followed by strict posturing seems to be a simple and effective treatment for unclosed holes.

  6. Astrophysical black holes

    CERN Document Server

    Gorini, Vittorio; Moschella, Ugo; Treves, Aldo; Colpi, Monica

    2016-01-01

    Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.

  7. Strain-induced fermi contour anisotropy of GaAs 2D holes.

    Science.gov (United States)

    Shabani, J; Shayegan, M; Winkler, R

    2008-03-07

    We report measurements of magnetoresistance commensurability peaks, induced by a square array of antidots, in GaAs (311)A two-dimensional holes as a function of applied in-plane strain. The data directly probe the shapes of the Fermi contours of the two spin subbands that are split thanks to the spin-orbit interaction and strain. The experimental results are in quantitative agreement with the predictions of accurate energy band calculations, and reveal that the majority spin subband has a severely distorted Fermi contour whose anisotropy can be tuned with strain.

  8. Formation of 2D-PhCs with missing holes based on Si-layers by EBL

    Science.gov (United States)

    Utkin, D. E.; Shklyev, A. A.; Tsarev, A. V.; Latyshev, A. V.

    2017-11-01

    The fabrication of the periodic structures, that is two-dimensional photonic crystals (2D PhCs) based on Si-materials by electron beam lithography (EBL) technique has been studied. We have investigated basic lithography processes such as designing, exposition, development, etching and others. The developed top-down approach allows close-packed arrays of elements and holes to be formed in nanometre range. This can be used to produce 2D PhCs with emitting micro-cavities (missing holes) with lateral size parameters with an accuracy of about 2% in the Si (100) substrate and in silicon-on-insulator structures. Such accuracy is expected to be sufficient for obtaining the cavities-coupling radiation interference from large areas of 2D PhCs.

  9. Fabrication of large area nanoprism arrays and their application for surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Cui, B; Clime, L; Li, K; Veres, T

    2008-01-01

    This work demonstrates the fabrication of metallic nanoprism (triangular nanostructure) arrays using a low-cost and high-throughput process. In the method, the triangular structure is defined by the shadow of a pyramid during angle evaporation of a metal etching mask. The pyramids were created by nanoimprint lithography in polymethylmethacrylate (PMMA) using a mould having an inverse-pyramid-shaped hole array formed by KOH wet etching of silicon. Silver and gold nanoprism arrays with a period of 200 nm and an edge length of 100 nm have been fabricated and used as effective substrates for surface enhanced Raman spectroscopy (SERS) detection of rhodamine 6G (R6G) molecules. Numerical calculations confirmed the great enhancement of electric field near the sharp nanoprism corners, as well as the detrimental effect of the chromium adhesion layer on localized surface plasmon resonance. The current method can also be used to fabricate non-equilateral nanoprism and three-dimensional (3D) nanopyramid arrays, and it can be readily extended to other metals

  10. Insertion characteristics and placement of the Mid-Scala electrode array in human temporal bones using detailed cone beam computed tomography.

    Science.gov (United States)

    Dietz, Aarno; Gazibegovic, Dzemal; Tervaniemi, Jyrki; Vartiainen, Veli-Matti; Löppönen, Heikki

    2016-12-01

    The aim of this study was to evaluate the insertion results and placement of the new Advanced Bionics HiFocus Mid-Scala (HFms) electrode array, inserted through the round window membrane, in eight fresh human temporal bones using cone beam computed tomography (CBCT). Pre- and post-insertion CBCT scans were registered to create a 3D reconstruction of the cochlea with the array inserted. With an image fusion technique both the bony edges of the cochlea and the electrode array in situ could accurately be determined, thus enabling to identify the exact position of the electrode array within the scala tympani. Vertical and horizontal scalar location was measured at four points along the cochlea base at an angular insertion depth of 90°, 180° and 270° and at electrode 16, the most basal electrode. Smooth insertion through the round window membrane was possible in all temporal bones. The imaging results showed that there were no dislocations from the scala tympani into the scala vestibule. The HFms electrode was positioned in the middle of the scala along the whole electrode array in three out of the eight bones and in 62 % of the individual locations measured along the base of the cochlea. In only one cochlea a close proximity of the electrode with the basilar membrane was observed, indicating possible contact with the basilar membrane. The results and assessments presented in this study appear to be highly accurate. Although a further validation including histopathology is needed, the image fusion technique described in this study represents currently the most accurate method for intracochlear electrode assessment obtainable with CBCT.

  11. Black holes in binary stars

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1996-01-01

    Introduction Distinguishing neutron stars and black holes Optical companions and dynamical masses X-ray signatures of the nature of a compact object Structure and evolution of black-hole binaries High-mass black-hole binaries Low-mass black-hole binaries Low-mass black holes Formation of black holes

  12. Laser induced ultrasonic phased array using full matrix capture data acquisition and total focusing method.

    Science.gov (United States)

    Stratoudaki, Theodosia; Clark, Matt; Wilcox, Paul D

    2016-09-19

    Laser ultrasonics is a technique where lasers are employed to generate and detect ultrasound. A data collection method (full matrix capture) and a post processing imaging algorithm, the total focusing method, both developed for ultrasonic arrays, are modified and used in order to enhance the capabilities of laser ultrasonics for nondestructive testing by improving defect detectability and increasing spatial resolution. In this way, a laser induced ultrasonic phased array is synthesized. A model is developed and compared with experimental results from aluminum samples with side drilled holes and slots at depths of 5 - 20 mm from the surface.

  13. Facile fabrication of nanofluidic diode membranes using anodic aluminium oxide

    Science.gov (United States)

    Wu, Songmei; Wildhaber, Fabien; Vazquez-Mena, Oscar; Bertsch, Arnaud; Brugger, Juergen; Renaud, Philippe

    2012-08-01

    Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al2O3/SiO2 (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al2O3 (positive) and SiO2 (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion.Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al2O3/SiO2 (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al2O3

  14. The stable problem of the black-hole connected region in the Schwarzschild black hole

    OpenAIRE

    Tian, Guihua

    2005-01-01

    The stability of the Schwarzschild black hole is studied. Using the Painlev\\'{e} coordinate, our region can be defined as the black-hole-connected region(r>2m, see text) of the Schwarzschild black hole or the white-hole-connected region(r>2m, see text) of the Schwarzschild black hole. We study the stable problems of the black-hole-connected region. The conclusions are: (1) in the black-hole-connected region, the initially regular perturbation fields must have real frequency or complex frequen...

  15. Rotating black holes at future colliders. III. Determination of black hole evolution

    International Nuclear Information System (INIS)

    Ida, Daisuke; Oda, Kin-ya; Park, Seong Chan

    2006-01-01

    TeV scale gravity scenario predicts that the black hole production dominates over all other interactions above the scale and that the Large Hadron Collider will be a black hole factory. Such higher-dimensional black holes mainly decay into the standard model fields via the Hawking radiation whose spectrum can be computed from the greybody factor. Here we complete the series of our work by showing the greybody factors and the resultant spectra for the brane-localized spinor and vector field emissions for arbitrary frequencies. Combining these results with the previous works, we determine the complete radiation spectra and the subsequent time evolution of the black hole. We find that, for a typical event, well more than half a black hole mass is emitted when the hole is still highly rotating, confirming our previous claim that it is important to take into account the angular momentum of black holes

  16. Etching holes in graphene supercapacitor electrodes for faster performance

    International Nuclear Information System (INIS)

    Ervin, Matthew H

    2015-01-01

    Graphene is being widely investigated as a material to replace activated carbon in supercapacitor (electrochemical capacitor) electrodes. Supercapacitors have much higher energy density, but are typically slow devices (∼0.1 Hz) compared to other types of capacitors. Here, top-down semiconductor processing has been applied to graphene-based electrodes in order to fabricate ordered arrays of holes through the graphene electrodes. This is demonstrated to increase the speed of the electrodes by reducing the ionic impedance through the electrode thickness. This approach may also be applicable to speeding up other types of devices, such as batteries and sensors, that use porous electrodes. (special)

  17. Black holes. Chapter 6

    International Nuclear Information System (INIS)

    Penrose, R.

    1980-01-01

    Conditions for the formation of a black hole are considered, and the properties of black holes. The possibility of Cygnus X-1 as a black hole is discussed. Einstein's theory of general relativity in relation to the formation of black holes is discussed. (U.K.)

  18. Statistical black-hole thermodynamics

    International Nuclear Information System (INIS)

    Bekenstein, J.D.

    1975-01-01

    Traditional methods from statistical thermodynamics, with appropriate modifications, are used to study several problems in black-hole thermodynamics. Jaynes's maximum-uncertainty method for computing probabilities is used to show that the earlier-formulated generalized second law is respected in statistically averaged form in the process of spontaneous radiation by a Kerr black hole discovered by Hawking, and also in the case of a Schwarzschild hole immersed in a bath of black-body radiation, however cold. The generalized second law is used to motivate a maximum-entropy principle for determining the equilibrium probability distribution for a system containing a black hole. As an application we derive the distribution for the radiation in equilibrium with a Kerr hole (it is found to agree with what would be expected from Hawking's results) and the form of the associated distribution among Kerr black-hole solution states of definite mass. The same results are shown to follow from a statistical interpretation of the concept of black-hole entropy as the natural logarithm of the number of possible interior configurations that are compatible with the given exterior black-hole state. We also formulate a Jaynes-type maximum-uncertainty principle for black holes, and apply it to obtain the probability distribution among Kerr solution states for an isolated radiating Kerr hole

  19. Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

    International Nuclear Information System (INIS)

    Wu, Ming-Chung; Chen, Shih-Wen; Li, Jia-Han; Chou, Yi; Lin, Jhih-Fong; Chen, Yang-Fang; Su, Wei-Fang

    2012-01-01

    In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: ► We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. ► These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. ► Adding the Au nanoparticles can give more functionalities for sensing applications.

  20. Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ming-Chung [Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 333-02, Taiwan (China); Chen, Shih-Wen; Li, Jia-Han [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chou, Yi; Lin, Jhih-Fong [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chen, Yang-Fang [Department of Physics, National Taiwan University, Taipei 106-17, Taiwan (China); Su, Wei-Fang, E-mail: suwf@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China)

    2012-11-15

    In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: Black-Right-Pointing-Pointer We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. Black-Right-Pointing-Pointer These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. Black-Right-Pointing-Pointer Adding the Au nanoparticles can give more functionalities for sensing applications.

  1. Transferable, conductive TiO{sub 2} nanotube membranes for optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Guohua [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway); Chen, Ting [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Sun, Yunlan; Chen, Guang [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Wang, Kaiying, E-mail: Kaiying.Wang@hbv.no [Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway)

    2014-08-30

    Graphical abstract: An optoelectronic device with vertical architecture offers straight conducting filaments for electron transportation. - Highlights: • Highly porous TiO{sub 2} nanotube membranes are prepared by two-step anodization. • An optoelectronic device is integrated with photocurrent transportation along the nanotube axial. • Straight conducting nano-filaments are beneficial for electron transportation. • Photoconductive performances are demonstrated under front/back-illumination. - Abstract: We report a facile approach for preparing free-standing and crystalline TiO{sub 2} nanotube membranes (TNMs) by taking advantage of differential mechanical stress between two anodic layers. The membrane exhibits visible light transmittance (∼40%) and UV absorption (∼99%) with good flexibility, which is favorable to integrate with substrates in optoelectronics. A sandwich-type device is assembled through stacking the membrane and substrates. The dependence of current-perpendicular-to-membrane vs applied voltage shows a remarkable photoconductive performance for both front and back illumination. The photocurrent value increases ∼2 or 3 orders magnitude under UV light radiation as compared to that in darkness. The photoresponse is arisen from high internal gain caused by hole trapping along the nanotube walls. This work is crucial for understanding intrinsic optical properties of nanostructured membranes.

  2. Jet array impingement flow distributions and heat transfer characteristics. Effects of initial crossflow and nonuniform array geometry. [gas turbine engine component cooling

    Science.gov (United States)

    Florschuetz, L. W.; Metzger, D. E.; Su, C. C.; Isoda, Y.; Tseng, H. H.

    1982-01-01

    Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. The configurations considered are intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The effects of an initial crossflow which approaches the array through an upstream extension of the channel are considered. Flow distributions as well as heat transfer coefficients and adiabatic wall temperatures resolved to one streamwise hole spacing were measured as a function of the initial crossflow rate and temperature relative to the jet flow rate and temperature. Both Nusselt number profiles and dimensionless adiabatic wall temperature (effectiveness) profiles are presented and discussed. Special test results which show a significant reduction of jet orifice discharge coefficients owing to the effect of a confined crossflow are also presented, along with a flow distribution model which incorporates those effects. A nonuniform array flow distribution model is developed and validated.

  3. Black hole hair removal

    International Nuclear Information System (INIS)

    Banerjee, Nabamita; Mandal, Ipsita; Sen, Ashoke

    2009-01-01

    Macroscopic entropy of an extremal black hole is expected to be determined completely by its near horizon geometry. Thus two black holes with identical near horizon geometries should have identical macroscopic entropy, and the expected equality between macroscopic and microscopic entropies will then imply that they have identical degeneracies of microstates. An apparent counterexample is provided by the 4D-5D lift relating BMPV black hole to a four dimensional black hole. The two black holes have identical near horizon geometries but different microscopic spectrum. We suggest that this discrepancy can be accounted for by black hole hair - degrees of freedom living outside the horizon and contributing to the degeneracies. We identify these degrees of freedom for both the four and the five dimensional black holes and show that after their contributions are removed from the microscopic degeneracies of the respective systems, the result for the four and five dimensional black holes match exactly.

  4. A review of recent advances in molecular simulation of graphene-derived membranes for gas separation

    Science.gov (United States)

    Fatemi, Seyyed Mahmood; Abbasi, Zeynab; Rajabzadeh, Halimeh; Hashemizadeh, Seyyed Ali; Deldar, Amir Noori

    2017-07-01

    To obtain an ideal membrane for gas separation the following three characteristics should be considered: the membrane should be as thin as possible, be mechanically robust, and have well-defined pore sizes. These features will maximize its solvent flux, preserve it from fracture, and guarantee its selectivity. These attractive properties of graphene-derived membranes introduce them as appropriate candidates for gas separation and gas molecular-sieving processes in nanoscale dimensions. The current effort has focused on two issues, including the review of the most newly progression on drilling holes in single graphene membranes for making ultrathin membranes for gas separation, and studying functionalized nanoporous sheet and graphene-derived membranes, including doped graphene, graphene oxide, fluorographene, and reduced graphene oxide from theoretical perspectives for making functional coatings for nano ultrafiltration for gas separation. We investigated the basic mechanism of separation by membranes derived from graphene and relevant possible applications. Functionalized nanoporous membranes as novel approach are characterized by low energy cost in realizing high throughput molecular-sieving separation.

  5. Fabrication of Arrays of Metal and Metal Oxide Nanotubes by Shadow Evaporation

    NARCIS (Netherlands)

    Dickey, Michael D.; Weiss, Emily A.; Smythe, Elizabeth J.; Chiechi, Ryan C.; Capasso, Federico; Whitesides, George M.

    2008-01-01

    This paper describes a simple technique for fabricating uniform arrays of metal and metal oxide nanotubes with controlled heights and diameters. The technique involves depositing material onto an anodized aluminum oxide (AAO) membrane template using a collimated electron beam evaporation source. The

  6. Applications of Flexible Ultrasonic Transducer Array for Defect Detection at 150 °C

    Directory of Open Access Journals (Sweden)

    Jiunn-Woei Liaw

    2013-01-01

    Full Text Available In this study, the feasibility of using a one dimensional 16-element flexible ultrasonic transducer (FUT array for nondestructive testing at 150 °C is demonstrated. The FUT arrays were made by a sol-gel sprayed piezoelectric film technology; a PZT composite film was sprayed on a titanium foil of 75 µm thickness. Since the FUT array is flexible, it was attached to a steel pipe with an outer diameter of 89 mm and a wall thickness of 6.5 mm at 150 °C. Using the ultrasonic pulse-echo mode, pipe thickness measurements could be performed. Moreover, using the ultrasonic pulse-echo and pitch-catch modes of each element of FUT array, the defect detection was performed on an Al alloy block of 30 mm thickness with a side-drilled hole (SDH of f3 mm at 150 °C. In addition, a post-processing algorithm based on the total focusing method was used to process the full matrix of these A-scan signals of each single transmitter and multi-receivers, and then the phase-array image was obtained to indicate this defect- SDH. Both results show the capability of FUT array being operated at 150 °C for the corrosion and defect detections.

  7. Template-based preparation of free-standing semiconducting polymeric nanorod arrays on conductive substrates.

    Science.gov (United States)

    Haberkorn, Niko; Weber, Stefan A L; Berger, Rüdiger; Theato, Patrick

    2010-06-01

    We describe the synthesis and characterization of a cross-linkable siloxane-derivatized tetraphenylbenzidine (DTMS-TPD), which was used for the fabrication of semiconducting highly ordered nanorod arrays on conductive indium tin oxide or Pt-coated substrates. The stepwise process allow fabricating of macroscopic areas of well-ordered free-standing nanorod arrays, which feature a high resistance against organic solvents, semiconducting properties and a good adhesion to the substrate. Thin films of the TPD derivate with good hole-conducting properties could be prepared by cross-linking and covalently attaching to hydroxylated substrates utilizing an initiator-free thermal curing at 160 degrees C. The nanorod arrays composed of cross-linked DTMS-TPD were fabricated by an anodic aluminum oxide (AAO) template approach. Furthermore, the nanorod arrays were investigated by a recently introduced method allowing to probe local conductivity on fragile structures. It revealed that more than 98% of the nanorods exhibit electrical conductance and consequently feature a good electrical contact to the substrate. The prepared nanorod arrays have the potential to find application in the fabrication of multilayered device architectures for building well-ordered bulk-heterojunction solar cells.

  8. A microneedle array able to inject tens of thousands of cells simultaneously

    Science.gov (United States)

    Teichert, Gregory H.; Burnett, Sandra; Jensen, Brian D.

    2013-09-01

    This paper presents a biological microelectromechanical system for injecting foreign particles into thousands of cells simultaneously. The system inserts an array of microneedles into a monolayer of cells, and the foreign particles enter the cells by diffusion. The needle array is fabricated using a series of deep reactive ion etches and produces about 4 million needles that average 1 μm in diameter and 8 μm in length with 10 μm spacing. The insertion of the needles is controlled through a compliant suspension. The compliant suspension was designed to provide for needle motion into the cells while restraining rotations or transverse motions that could result in tearing of the cell membranes. Testing was performed using propidium iodide, a membrane impermeable dye, injected into HeLa cells. Average cell survivability was found to be 97.7%, and up to 97.9% of the surviving cells received the propidium iodide.

  9. A microneedle array able to inject tens of thousands of cells simultaneously

    International Nuclear Information System (INIS)

    Teichert, Gregory H; Jensen, Brian D; Burnett, Sandra

    2013-01-01

    This paper presents a biological microelectromechanical system for injecting foreign particles into thousands of cells simultaneously. The system inserts an array of microneedles into a monolayer of cells, and the foreign particles enter the cells by diffusion. The needle array is fabricated using a series of deep reactive ion etches and produces about 4 million needles that average 1 μm in diameter and 8 μm in length with 10 μm spacing. The insertion of the needles is controlled through a compliant suspension. The compliant suspension was designed to provide for needle motion into the cells while restraining rotations or transverse motions that could result in tearing of the cell membranes. Testing was performed using propidium iodide, a membrane impermeable dye, injected into HeLa cells. Average cell survivability was found to be 97.7%, and up to 97.9% of the surviving cells received the propidium iodide. (paper)

  10. Shear Adhesion of Tapered Nanopillar Arrays.

    Science.gov (United States)

    Cho, Younghyun; Minsky, Helen K; Jiang, Yijie; Yin, Kaiyang; Turner, Kevin T; Yang, Shu

    2018-04-04

    Tapered nanopillars with various cross sections, including cone-shaped, stepwise, and pencil-like structures (300 nm in diameter at the base of the pillars and 1.1 μm in height), are prepared from epoxy resin templated by nanoporous anodic aluminum oxide (AAO) membranes. The effect of pillar geometry on the shear adhesion behavior of these nanopillar arrays is investigated via sliding experiments in a nanoindentation system. In a previous study of arrays with the same geometry, it was shown that cone-shaped nanopillars exhibit the highest adhesion under normal loading while stepwise and pencil-like nanopillars exhibit lower normal adhesion strength due to significant deformation of the pillars that occurs with increasing indentation depth. Contrary to the previous studies, here, we show that pencil-like nanopillars exhibit the highest shear adhesion strength at all indentation depths among three types of nanopillar arrays and that the shear adhesion increases with greater indentation depth due to the higher bending stiffness and closer packing of the pencil-like nanopillar array. Finite element simulations are used to elucidate the deformation of the pillars during the sliding experiments and agree with the nanoindentation-based sliding measurements. The experiments and finite element simulations together demonstrate that the shape of the nanopillars plays a key role in shear adhesion and that the mechanism is quite different from that of adhesion under normal loading.

  11. Micromachined capacitive ultrasonic immersion transducer array

    Science.gov (United States)

    Jin, Xuecheng

    Capacitive micromachined ultrasonic transducers (cMUTs) have emerged as an attractive alternative to conventional piezoelectric ultrasonic transducers. They offer performance advantages of wide bandwidth and sensitivity that have heretofore been attainable. In addition, micromachining technology, which has benefited from the fast-growing microelectronics industry, enables cMUT array fabrication and electronics integration. This thesis describes the design and fabrication of micromachined capacitive ultrasonic immersion transducer arrays. The basic transducer electrical equivalent circuit is derived from Mason's theory. The effects of Lamb waves and Stoneley waves on cross coupling and acoustic losses are discussed. Electrical parasitics such as series resistance and shunt capacitance are also included in the model of the transducer. Transducer fabrication technology is systematically studied. Device dimension control in both vertical and horizontal directions, process alternatives and variations in membrane formation, via etch and cavity sealing, and metalization as well as their impact on transducer performance are summarized. Both 64 and 128 element 1-D array transducers are fabricated. Transducers are characterized in terms of electrical input impedance, bandwidth, sensitivity, dynamic range, impulse response and angular response, and their performance is compared with theoretical simulation. Various schemes for cross coupling reduction is analyzed, implemented, and verified with both experiments and theory. Preliminary results of immersion imaging are presented using 64 elements 1-D array transducers for active source imaging.

  12. Superconducting Properties of Lead-Bismuth Films Controlled by Ferromagnetic Nanowire Arrays

    Science.gov (United States)

    Ye, Zuxin; Lyuksyutov, Igor F.; Wu, Wenhao; Naugle, Donald G.

    2011-03-01

    Superconducting properties of lead-bismuth (82% Pb and 18% Bi) alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb 82 Bi 18 films are then quench-condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb 82 Bi 18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and the material variety was observed.

  13. Brane holes

    International Nuclear Information System (INIS)

    Frolov, Valeri P.; Mukohyama, Shinji

    2011-01-01

    The aim of this paper is to demonstrate that in models with large extra dimensions under special conditions one can extract information from the interior of 4D black holes. For this purpose we study an induced geometry on a test brane in the background of a higher-dimensional static black string or a black brane. We show that, at the intersection surface of the test brane and the bulk black string or brane, the induced metric has an event horizon, so that the test brane contains a black hole. We call it a brane hole. When the test brane moves with a constant velocity V with respect to the bulk black object, it also has a brane hole, but its gravitational radius r e is greater than the size of the bulk black string or brane r 0 by the factor (1-V 2 ) -1 . We show that bulk ''photon'' emitted in the region between r 0 and r e can meet the test brane again at a point outside r e . From the point of view of observers on the test brane, the events of emission and capture of the bulk photon are connected by a spacelike curve in the induced geometry. This shows an example in which extra dimensions can be used to extract information from the interior of a lower-dimensional black object. Instead of the bulk black string or brane, one can also consider a bulk geometry without a horizon. We show that nevertheless the induced geometry on the moving test brane can include a brane hole. In such a case the extra dimensions can be used to extract information from the complete region of the brane-hole interior. We discuss thermodynamic properties of brane holes and interesting questions which arise when such an extra-dimensional channel for the information mining exists.

  14. Contact CMOS imaging of gaseous oxygen sensor array.

    Science.gov (United States)

    Daivasagaya, Daisy S; Yao, Lei; Yi Yung, Ka; Hajj-Hassan, Mohamad; Cheung, Maurice C; Chodavarapu, Vamsy P; Bright, Frank V

    2011-10-01

    We describe a compact luminescent gaseous oxygen (O 2 ) sensor microsystem based on the direct integration of sensor elements with a polymeric optical filter and placed on a low power complementary metal-oxide semiconductor (CMOS) imager integrated circuit (IC). The sensor operates on the measurement of excited-state emission intensity of O 2 -sensitive luminophore molecules tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp) 3 ] 2+ ) encapsulated within sol-gel derived xerogel thin films. The polymeric optical filter is made with polydimethylsiloxane (PDMS) that is mixed with a dye (Sudan-II). The PDMS membrane surface is molded to incorporate arrays of trapezoidal microstructures that serve to focus the optical sensor signals on to the imager pixels. The molded PDMS membrane is then attached with the PDMS color filter. The xerogel sensor arrays are contact printed on top of the PDMS trapezoidal lens-like microstructures. The CMOS imager uses a 32 × 32 (1024 elements) array of active pixel sensors and each pixel includes a high-gain phototransistor to convert the detected optical signals into electrical currents. Correlated double sampling circuit, pixel address, digital control and signal integration circuits are also implemented on-chip. The CMOS imager data is read out as a serial coded signal. The CMOS imager consumes a static power of 320 µW and an average dynamic power of 625 µW when operating at 100 Hz sampling frequency and 1.8 V DC. This CMOS sensor system provides a useful platform for the development of miniaturized optical chemical gas sensors.

  15. Microbial communities and their potential for degradation of dissolved organic carbon in cryoconite hole environments of Himalaya and Antarctica.

    Science.gov (United States)

    Sanyal, Aritri; Antony, Runa; Samui, Gautami; Thamban, Meloth

    2018-03-01

    Cryoconite holes (cylindrical melt-holes on the glacier surface) are important hydrological and biological systems within glacial environments that support diverse microbial communities and biogeochemical processes. This study describes retrievable heterotrophic microbes in cryoconite hole water from three geographically distinct sites in Antarctica, and a Himalayan glacier, along with their potential to degrade organic compounds found in these environments. Microcosm experiments (22 days) show that 13-60% of the dissolved organic carbon in the water within cryoconite holes is bio-available to resident microbes. Biodegradation tests of organic compounds such as lactate, acetate, formate, propionate and oxalate that are present in cryoconite hole water show that microbes have good potential to metabolize the compounds tested. Substrate utilization tests on Biolog Ecoplate show that microbial communities in the Himalayan samples are able to oxidize a diverse array of organic substrates including carbohydrates, carboxylic acids, amino acids, amines/amides and polymers, while Antarctic communities generally utilized complex polymers. In addition, as determined by the extracellular enzyme activities, majority of the microbes (82%, total of 355) isolated in this study (Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria and Basidiomycota) had ability to degrade a variety of compounds such as proteins, lipids, carbohydrates, cellulose and lignin that are documented to be present within cryoconite holes. Thus, microbial communities have good potential to metabolize organic compounds found in the cryoconite hole environment, thereby influencing the water chemistry in these holes. Moreover, microbes exported downstream during melting and flushing of cryoconite holes may participate in carbon cycling processes in recipient ecosystems. Copyright © 2018 Elsevier GmbH. All rights reserved.

  16. Utility of microscope-integrated optical coherence tomography (MIOCT) in the treatment of myopic macular hole retinal detachment.

    Science.gov (United States)

    Kumar, Atul; Kakkar, Prateek; Ravani, Raghav Dinesh; Markan, Ashish

    2017-07-14

    Macular hole-associated retinal detachment in high myopia is described as a final stage in progression of myopic traction maculopathy (MTM). 1â€"3 Shimada et al 4 described the progressive stages of MTM from macular retinoschisis to serous retinal detachment in high myopia. Stage 4 MTM is characterised as disappearance of retinoschisis with progression to retinal detachment due to macular hole formation. It is hypothesised that vitreoschisis and abnormal vitreo-retinal interface create the premacular tangential traction. 5 6 Intraoperative triamcinolone acetonide is used to visualise the residual posterior vitreous cortex (PVC). We hereby describe the utility of microscope-integrated optical coherence tomography (MIOCT) in assisting complete removal of PVC and internal limiting membrane (ILM) peeling with multilayered inverted ILM flap in the treatment of myopic macular hole retinal detachment. MIOCT helped identify vitreoschisis and confirm the position of ILM flaps over the macular hole intraoperatively. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  17. Superconductivity of a Sn film controlled by an array of Co nanowires

    Science.gov (United States)

    Wei, Z.; Ye, Z.; Rathnayaka, K. D. D.; Lyuksyutov, I. F.; Wu, W.; Naugle, D. G.

    2012-09-01

    Superconducting properties of a hybrid structure composed of ferromagnetic Co nanowire arrays and a superconducting Sn film have been investigated. Ordered Co nanowires arrays with 60 nm, 150 nm and 200 nm diameter were electroplated into the pores of self organized Anodic Aluminum Oxide (AAO) membranes. Hysteretic dependence of the Sn film superconducting properties on applied magnetic field and critical current enhancement at moderate fields has been observed. This behavior strongly depends on the ratio of the Sn film thickness to the Co nanowire diameter.

  18. Superconductivity of a Sn film controlled by an array of Co nanowires

    International Nuclear Information System (INIS)

    Wei, Z.; Ye, Z.; Rathnayaka, K.D.D.; Lyuksyutov, I.F.; Wu, W.; Naugle, D.G.

    2012-01-01

    Superconducting properties of a hybrid structure composed of ferromagnetic Co nanowire arrays and a superconducting Sn film have been investigated. Ordered Co nanowires arrays with 60 nm, 150 nm and 200 nm diameter were electroplated into the pores of self organized Anodic Aluminum Oxide (AAO) membranes. Hysteretic dependence of the Sn film superconducting properties on applied magnetic field and critical current enhancement at moderate fields has been observed. This behavior strongly depends on the ratio of the Sn film thickness to the Co nanowire diameter.

  19. Vascular Displacement in Idiopathic Macular Hole after Single-layered Inverted Internal Limiting Membrane Flap Surgery.

    Science.gov (United States)

    Lee, Jae Jung; Lee, In Ho; Park, Keun Heung; Pak, Kang Yeun; Park, Sung Who; Byon, Ik Soo; Lee, Ji Eun

    2017-08-01

    To compare vascular displacement in the macula after surgical closure of idiopathic macular hole (MH) after single-layered inverted internal limiting membrane (ILM) flap technique and conventional ILM removal. This retrospective study included patients who underwent either vitrectomy and ILM removal only or vitrectomy with single-layered inverted ILM flap for idiopathic MH larger than 400 μm from 2012 to 2015. A customized program compared the positions of the retinal vessels in the macula between preoperative and postoperative photographs. En face images of 6 × 6 mm optical coherence tomography volume scans were registered to calculate the scale. Retinal vessel displacement was measured as a vector value by comparing its location in 16 sectors of a grid partitioned into eight sectors in two rings (inner, 2 to 4 mm; outer, 4 to 6 mm). The distance and angle of displacement were calculated as an average vector and were compared between the two groups for whole sectors, inner ring, outer ring, and for each sector. Twenty patients were included in the ILM flap group and 22 in the ILM removal group. There were no statistical differences between the groups for baseline characteristics. The average displacement in the ILM flap group and the ILM removal group was 56.6 μm at -3.4° and 64.9 μm at -2.7°, respectively, for the whole sectors (p = 0.900), 76.1 μm at -1.1° and 87.3 μm at -0.9° for the inner ring (p = 0.980), and 37.4 μm at -8.2° and 42.7 μm at -6.3° for the outer ring (p = 0.314). There was no statistical difference in the displacement of each of the sectors. Postoperative topographic changes showed no significant differences between the ILM flap and the ILM removal group for idiopathic MH. The single-layered ILM flap technique did not appear to cause additional displacement of the retinal vessels in the macula. © 2017 The Korean Ophthalmological Society

  20. Black holes are warm

    International Nuclear Information System (INIS)

    Ravndal, F.

    1978-01-01

    Applying Einstein's theory of gravitation to black holes and their interactions with their surroundings leads to the conclusion that the sum of the surface areas of several black holes can never become less. This is shown to be analogous to entropy in thermodynamics, and the term entropy is also thus applied to black holes. Continuing, expressions are found for the temperature of a black hole and its luminosity. Thermal radiation is shown to lead to explosion of the black hole. Numerical examples are discussed involving the temperature, the mass, the luminosity and the lifetime of black mini-holes. It is pointed out that no explosions corresponding to the prediction have been observed. It is also shown that the principle of conservation of leptons and baryons is broken by hot black holes, but that this need not be a problem. The related concept of instantons is cited. It is thought that understanding of thermal radiation from black holes may be important for the development of a quantified gravitation theory. (JIW)

  1. Neutral-helium-atom diffraction from a micron-scale periodic structure: Photonic-crystal-membrane characterization

    Science.gov (United States)

    Nesse, Torstein; Eder, Sabrina D.; Kaltenbacher, Thomas; Grepstad, Jon Olav; Simonsen, Ingve; Holst, Bodil

    2017-06-01

    Surface scattering of neutral helium beams created by supersonic expansion is an established technique for measuring structural and dynamical properties of surfaces on the atomic scale. Helium beams have also been used in Fraunhofer and Fresnel diffraction experiments. Due to the short wavelength of the atom beams of typically 0.1 nm or less, Fraunhofer diffraction experiments in transmission have so far been limited to grating structures with a period (pitch) of up to 200 nm. However, larger periods are of interest for several applications, for example, for the characterization of photonic-crystal-membrane structures, where the period is typically in the micron to high submicron range. Here we present helium atom diffraction measurements of a photonic-crystal-membrane structure with a two-dimensional square lattice of 100 ×100 circular holes. The nominal period and the hole radius were 490 and 100 nm, respectively. To our knowledge this is the largest period that has been measured with helium diffraction. The helium diffraction measurements are interpreted using a model based on the helium beam characteristics. It is demonstrated how to successfully extract values from the experimental data for the average period of the grating, the hole diameter, and the width of the virtual source used to model the helium beam.

  2. Hole history, rotary hole DC-3

    International Nuclear Information System (INIS)

    1977-10-01

    Purpose of hole DC-3 was to drill into the Umtanum basalt flow using both conventional rotary and core drilling methods. The borehole is to be utilized for geophysical logging, future hydrological testing, and the future installation of a borehole laboratory for long-term pressure, seismic, and moisture migration or accumulation recording in the Umtanum basalt flow in support of the Basalt Waste Isolation Program. Hole DC-3 is located east of the 200 West barricaded area on the Hanford reservation

  3. 'Death Star' Galaxy Black Hole Fires at Neighboring Galaxy

    Science.gov (United States)

    2008-12-01

    This "death star" galaxy was discovered through the combined efforts of both space and ground-based telescopes. NASA's Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope were part of the effort. The Very Large Array telescope, Socorro, N.M., and the Multi-Element Radio Linked Interferometer Network (MERLIN) telescopes in the United Kingdom also were needed for the finding. Illustration of Jet Striking Galaxy (unlabeled) Illustration of Jet Striking Galaxy (unlabeled) "We've seen many jets produced by black holes, but this is the first time we've seen one punch into another galaxy like we're seeing here," said Dan Evans, a scientist at the Harvard-Smithsonian Center for Astrophysics and leader of the study. "This jet could be causing all sorts of problems for the smaller galaxy it is pummeling." Jets from super massive black holes produce high amounts of radiation, especially high-energy X-rays and gamma-rays, which can be lethal in large quantities. The combined effects of this radiation and particles traveling at almost the speed of light could severely damage the atmospheres of planets lying in the path of the jet. For example, protective layers of ozone in the upper atmosphere of planets could be destroyed. X-ray & Radio Full Field Image of 3C321 X-ray & Radio Full Field Image of 3C321 Jets produced by super massive black holes transport enormous amounts of energy far from black holes and enable them to affect matter on scales vastly larger than the size of the black hole. Learning more about jets is a key goal for astrophysical research. "We see jets all over the Universe, but we're still struggling to understand some of their basic properties," said co-investigator Martin Hardcastle of the University of Hertfordshire, United Kingdom. "This system of 3C321 gives us a chance to learn how they're affected when they slam into something - like a galaxy - and what they do after that." Optical Image of 3C321 Optical Image of 3C321 The

  4. Fabricating PFPE Membranes for Microfluidic Valves and Pumps

    Science.gov (United States)

    Greer, Frank; White, Victor E.; Lee, Michael C.; Willis, Peter A.; Grunthaner, Frank J.; Rolland, Jason; Rolland, Jason

    2009-01-01

    A process has been developed for fabricating membranes of a perfluoropolyether (PFPE) and integrating them into valves and pumps in laboratory-on-achip microfluidic devices. Membranes of poly(tetrafluoroethylene) [PTFE] and poly(dimethylsilane) [PDMS] have been considered for this purpose and found wanting. By making it possible to use PFPE instead of PTFE or PDMS, the present process expands the array of options for further development of microfluidic devices for diverse applications that could include detection of biochemicals of interest, detection of toxins and biowarfare agents, synthesis and analysis of proteins, medical diagnosis, and synthesis of fuels.

  5. Fabrication and flow characterization of vertically aligned carbon-nanotube/polymer membranes

    Science.gov (United States)

    Castellano, Richard; Meshot, Eric; Fornasiero, Francesco; Shan, Jerry

    2017-11-01

    Membranes with well-controlled nanopores are of interest for applications as diverse as chemical separations, water purification, and ``green'' power generation. In particular, membranes incorporating carbon nanotubes (CNTs) as through-pores have been shown to pass fluids at rates orders-of-magnitude faster than predicted by continuum theory. However, cost-effective and scalable solutions for fabricating such membranes are still an area of research. We describe a solution-based fabrication technique for creating polymer composite membranes from bulk nanotubes using electric-field alignment and electrophoretic concentration. We then focus on flow characterization of membranes with single-wall nanotube (SWNT) pores. We demonstrate membrane quality by size-exclusion testing and showing that the flowrate of different gasses scales as the square root of molecular weight. The gas flowrates and moisture-vapor-transmission rates are compared with theoretical predictions and with composite membranes -fabricated from CVD-grown SWNT arrays. Funded by DTRA Grant BA12PHM123.

  6. Influence of boundary geometry in domain wall propagation in magnetic films with asymmetric holes: Micromagnetic calculations

    International Nuclear Information System (INIS)

    Alija, A; Sobrado, I; Rodriguez-RodrIguez, G; Velez, M; Alameda, J M; MartIn, J I; Parrondo, J M R

    2010-01-01

    Micromagnetic simulations have been performed in uniaxial magnetic films with 2D array of asymmetric arrow shape holes. In order to understand the asymmetric pinning potential created by the holes, different boundary geometries conditions are used on the simulations. The depinning fields for forward and backward domain wall propagation have been calculated by the analysis of the energy landscapes as a function of the domain wall position. Domain wall depinning occurs preferentially at the free ends of the domain wall at the film boundaries. We have found that the domain wall propagation is different at the top/bottom boundaries of the simulated film which can be understood in terms of the magnetostatic energy and the chirality of the domain wall.

  7. Macular Buckling Surgery for Retinal Detachment Associated with Macular Hole in High Myopia Eye

    Directory of Open Access Journals (Sweden)

    Kenan Sönmez

    2017-12-01

    Full Text Available A 68-year-old woman presented to our clinic with a 1-month history of central scotoma and visual loss in her right eye. The best corrected visual acuity (BCVA was hand motion in her right eye. Fundus examination showed myopic chorioretinal degeneration in association with posterior staphyloma and the retina was slightly elevated throughout the macula. Optical coherence tomography (OCT revealed retinal detachment involving the posterior pole with a macular hole and staphyloma. The patient underwent pars plana vitrectomy, internal limiting membrane peeling, macular buckling, and perfluoropropane gas tamponade. At 3-month follow-up, her BCVA was improved to counting fingers at 1 meter and flattened retina with closed macular hole was observed by OCT. Myopic macular hole with retinal detachment associated with posterior staphyloma represent a challenge regarding their management and several surgical techniques have been described. Although satisfactory anatomical improvement is achieved in these eyes after surgery, the visual acuity outcomes may be poorer than expected due to the chorioretinal atrophy at the posterior pole.

  8. The International Pulsar Timing Array project: using pulsars as a gravitational wave detector

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, G; Burke-Spolaor, S; Champion, D [Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710 (Australia); Archibald, A [Department of Physics, McGill University, Montreal, PQ, H3A 2T8 (Canada); Arzoumanian, Z [CRESST/USRA, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Backer, D [Astronomy Department and Radio Astronomy Laboratory, University of California, Berkeley, CA 94720-3411 (United States); Bailes, M; Bhat, N D R [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn VIC 3122 (Australia); Burgay, M [Universita di Cagliari, Dipartimento di Fisica, SP Monserrato-Sestu km 0.7, 09042 Monserrato (Canada) (Italy); Cognard, I; Desvignes, G; Ferdman, R D [Station de Radioastronomie de Nanay, Observatoire de Paris, 18330 Nancay (France); Coles, W [Electrical and Computer Engineering, University of California at San Diego, La Jolla, CA (United States); Cordes, J [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Demorest, P [National Radio Astronomy Observatory (NRAO), Charlottesville, VA 22903 (United States); Finn, L [Center for Gravitational Wave Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Freire, P [Max-Planck-Institut fuer Radioastronomie, Auf Dem Huegel 69, 53121, Bonn (Germany); Gonzalez, M [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Hessels, J [Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam (Netherlands); Hotan, A, E-mail: george.hobbs@csiro.a [Department of Imaging and Applied Physics, Curtin University, Bentley, WA (Australia)

    2010-04-21

    The International Pulsar Timing Array project combines observations of pulsars from both northern and southern hemisphere observatories with the main aim of detecting ultra-low frequency (approx 10{sup -9}-10{sup -8} Hz) gravitational waves. Here we introduce the project, review the methods used to search for gravitational waves emitted from coalescing supermassive binary black-hole systems in the centres of merging galaxies and discuss the status of the project.

  9. Quantum aspects of black holes

    CERN Document Server

    2015-01-01

    Beginning with an overview of the theory of black holes by the editor, this book presents a collection of ten chapters by leading physicists dealing with the variety of quantum mechanical and quantum gravitational effects pertinent to black holes. The contributions address topics such as Hawking radiation, the thermodynamics of black holes, the information paradox and firewalls, Monsters, primordial black holes, self-gravitating Bose-Einstein condensates, the formation of small black holes in high energetic collisions of particles, minimal length effects in black holes and small black holes at the Large Hadron Collider. Viewed as a whole the collection provides stimulating reading for researchers and graduate students seeking a summary of the quantum features of black holes.

  10. TES arrays for the short wavelength band of the SAFARI instrument on SPICA

    Science.gov (United States)

    Khosropanah, P.; Hijmering, R.; Ridder, M.; Gao, J. R.; Morozov, D.; Mauskopf, P. D.; Trappe, N.; O'Sullivan, C.; Murphy, A.; Griffin, D.; Goldie, D.; Glowacka, D.; Withington, S.; Jackson, B. D.; Audley, M. D.; de Lange, G.

    2012-09-01

    SPICA is an infra-red (IR) telescope with a cryogenically cooled mirror (~5K) with three instruments on board, one of which is SAFARI that is an imaging Fourier Transform Spectrometer (FTS) with three bands covering the wavelength of 34-210 μm. We develop transition edge sensors (TES) array for short wavelength band (34-60 μm) of SAFARI. These are based on superconducting Ti/Au bilayer as TES bolometers with a Tc of about 105 mK and thin Ta film as IR absorbers on suspended silicon nitride (SiN) membranes. These membranes are supported by long and narrow SiN legs that act as weak thermal links between the TES and the bath. Previously an electrical noise equivalent power (NEP) of 4×10-19 W/√Hz was achieved for a single pixel of such detectors. As an intermediate step toward a full-size SAFARI array (43×43), we fabricated several 8×9 detector arrays. Here we describe the design and the outcome of the dark and optical tests of several of these devices. We achieved high yield (<93%) and high uniformity in terms of critical temperature (<5%) and normal resistance (7%) across the arrays. The measured dark NEPs are as low as 5×10-19 W/√Hz with a response time of about 1.4 ms at preferred operating bias point. The optical coupling is implemented using pyramidal horns array on the top and hemispherical cavity behind the chip that gives a measured total optical coupling efficiency of 30±7%.

  11. Effect of vertically aligned carbon nanotube density on the water flux and salt rejection in desalination membranes.

    Science.gov (United States)

    Trivedi, Samarth; Alameh, Kamal

    2016-01-01

    In this paper, vertically aligned carbon nanotube (VACNT) membranes of different densities are developed and their performances are investigated. VACNT arrays of densities 5 × 10(9), 10(10), 5 × 10(10) and 10(11) tubes cm(-2), are initially grown on 1 cm × 1 cm silicon substrates using chemical vapour deposition. A VACNT membrane is realised by attaching a 300 μm-thick 1 cm × 1 cm VACNT array on silicon to a 4″ glass substrate, applying polydimethylsiloxane (PDMS) through spin coating to fill the gaps between the VACNTs, and using a microtome to slice the VACNT-PDMS composite into 25-μm-thick membranes. Experimental results show that the permeability of the developed VACNT membranes increases with the density of the VACNTs, while the salt rejection is almost independent of the VACNT density. The best measured permeance is attained with a VACNT membrane having a CNT density of 10(11) tubes cm(-2) is 1203 LMH at 1 bar.

  12. Black holes and beyond

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for

  13. Large aperture deformable mirror with a transferred single-crystal silicon membrane actuated using large-stroke PZT Unimorph Actuators

    Science.gov (United States)

    Hishinumat, Yoshikazu; Yang, Eui - Hyeok (EH)

    2005-01-01

    We have demonstrated a large aperture (50 mm x 50 mm) continuous membrane deformable mirror (DM) with a large-stroke piezoelectric unimorph actuator array. The DM consists of a continuous, large aperture, silicon membrane 'transferred' in its entirety onto a 20 x 20 piezoelectric unimorph actuator array. A PZT unimorph actuator, 2.5 mm in diameter with optimized PZT/Si thickness and design showed a deflection of 5.7 [m at 20V. An assembled DM showed an operating frequency bandwidth of 30 kHz and influence function of approximately 30%.

  14. A micromachined membrane-based active probe for biomolecular mechanics measurement

    Science.gov (United States)

    Torun, H.; Sutanto, J.; Sarangapani, K. K.; Joseph, P.; Degertekin, F. L.; Zhu, C.

    2007-04-01

    A novel micromachined, membrane-based probe has been developed and fabricated as assays to enable parallel measurements. Each probe in the array can be individually actuated, and the membrane displacement can be measured with high resolution using an integrated diffraction-based optical interferometer. To illustrate its application in single-molecule mechanics experiments, this membrane probe was used to measure unbinding forces between L-selectin reconstituted in a polymer-cushioned lipid bilayer on the probe membrane and an antibody adsorbed on an atomic force microscope cantilever. Piconewton range forces between single pairs of interacting molecules were measured from the cantilever bending while using the membrane probe as an actuator. The integrated diffraction-based optical interferometer of the probe was demonstrated to have floor for frequencies as low as 3 Hz with a differential readout scheme. With soft probe membranes, this low noise level would be suitable for direct force measurements without the need for a cantilever. Furthermore, the probe membranes were shown to have 0.5 µm actuation range with a flat response up to 100 kHz, enabling measurements at fast speeds.

  15. Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes.

    Science.gov (United States)

    Qi, Y; Wang, Y; You, Q; Tsai, F; Liu, W

    2017-07-01

    PurposeTo report OCT appearance and surgical outcomes of full-thickness macular holes (MHs) accidentally caused by laser devices.Patients and methodsThis retrospective case series included 11 eyes of 11 patients with laser-induced MHs treated by pars plana vitrectomy, internal limiting membrane (ILM) peeling, and gas or silicone oil tamponade. Evaluations included a full ophthalmic examination, macular spectral-domain optical coherence tomography (SD-OCT), and fundus photography. Main outcome measures is MH closure and final visual acuity; the secondary outcome was the changes of retinal pigment epithelium and photoreceptor layer evaluated by sequential post-operative SD-OCT images.ResultsFive patients were accidentally injured by a yttrium aluminum garnet (YAG) laser and six patients by handheld laser. MH diameters ranged from 272 to 815 μm (mean, 505.5±163.0 μm) preoperatively. Best-corrected visual acuity (BCVA) improved from a mean of 0.90 logMAR (range, counting finger-8/20) preoperatively to a mean of 0.34 logMAR (range, a counting finger-20/20) postoperatively (P=0.001, t=4.521). Seven of 11 patients (63.6%) achieved a BCVA better than 10/20. Ten patients had a subfoveal hyperreflectivity and four patients had a focal choroidal depression subfoveal preoperatively. At the last follow-up, all 11 eyes demonstrated the following: closure of the macular hole, variable degrees of disruption of external limiting membrane (ELM) and outer photoreceptor ellipsoid and interdigitation bands. In 10 eyes, the disruption was in the form of focal defects in the outer retina. After surgery, the subfoveal hyperreflectivity and focal choroidal depression remained.ConclusionAccidental laser-induced full-thickness macular holes can be successfully closed with surgery. Inadvertent retinal injury from laser devices, especially handheld laser injury has occurred with increasing frequency in recent years. However, there is a paucity of data regarding these types of injuries

  16. Black Hole Coalescence: The Gravitational Wave Driven Phase

    Science.gov (United States)

    Schnittman, Jeremy D.

    2011-01-01

    When two supermassive black holes (SMBHS) approach within 1-10 mpc, gravitational wave (GW) losses begin to dominate the evolution of the binary, pushing the system to merge in a relatively small time. During this final inspiral regime, the system will emit copious energy in GWs, which should be directly detectable by pulsar timing arrays and space-based interferometers. At the same time, any gas or stars in the immediate vicinity of the merging 5MBHs can get heated and produce bright electromagnetic (EM) counterparts to the GW signals. We present here a number of possible mechanisms by which simultaneous EM and GW signals will yield valuable new information about galaxy evolution, accretion disk dynamics, and fundamental physics in the most extreme gravitational fields.

  17. Er:YAG delamination of immersed biological membranes using sealed flexible hollow waveguides

    Science.gov (United States)

    Sagi-Dolev, A. M.; Dror, Jacob; Inberg, Alexandra; Ferencz, J. R.; Croitoru, Nathan I.

    1996-04-01

    The radiation of Er-YAG laser ((lambda) equals 2.94 micrometer) gives selective interaction with tissues. The extinction in soft tissues is only a few micrometers and in hard tissues is of the order of hundreds of micrometers. This makes this type of laser very suitable for treatments in dentistry, orthopedy, or ophthalmology. Because the usual silica fibers are not transmitting the radiation at lambda equals 2.94 micrometer of this laser, many applications cannot be presently performed. Fused silica hollow fibers for Er-YAG radiation were developed in our laboratory and several possible applications in dentistry, orthopedy and ophthalmology were indicated. Hole opening and implantation preparation of teeth were experimented, using Er-YAG laser and hollow plastic waveguide delivery systems. Hole drilling in cow bones was demonstrated for applications in orthopedy. A new procedure of delivering Er-YAG radiation on fibrotic membranes of inner eggshell as a model of the membranes in eyes was developed employing silica hollow waveguides of 0.5 and 0.7 mm ID or a plastic waveguide of 1.0 mm ID. For this purpose waveguides with sealed distal tip were employed to enable us to approach the delivery system through liquid media near to the membrane. This experiment demonstrates the possibility of surgical applications in vitectomy in ophthalmology using Er-YAG laser and silica hollow waveguides.

  18. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  19. GSL-enriched membrane microdomains in innate immune responses.

    Science.gov (United States)

    Nakayama, Hitoshi; Ogawa, Hideoki; Takamori, Kenji; Iwabuchi, Kazuhisa

    2013-06-01

    Many pathogens target glycosphingolipids (GSLs), which, together with cholesterol, GPI-anchored proteins, and various signaling molecules, cluster on host cell membranes to form GSL-enriched membrane microdomains (lipid rafts). These GSL-enriched membrane microdomains may therefore be involved in host-pathogen interactions. Innate immune responses are triggered by the association of pathogens with phagocytes, such as neutrophils, macrophages and dendritic cells. Phagocytes express a diverse array of pattern-recognition receptors (PRRs), which sense invading microorganisms and trigger pathogen-specific signaling. PRRs can recognize highly conserved pathogen-associated molecular patterns expressed on microorganisms. The GSL lactosylceramide (LacCer, CDw17), which binds to various microorganisms, including Candida albicans, is expressed predominantly on the plasma membranes of human mature neutrophils and forms membrane microdomains together with the Src family tyrosine kinase Lyn. These LacCer-enriched membrane microdomains can mediate superoxide generation, migration, and phagocytosis, indicating that LacCer functions as a PRR in innate immunity. Moreover, the interactions of GSL-enriched membrane microdomains with membrane proteins, such as growth factor receptors, are important in mediating the physiological properties of these proteins. Similarly, we recently found that interactions between LacCer-enriched membrane microdomains and CD11b/CD18 (Mac-1, CR3, or αMβ2-integrin) are significant for neutrophil phagocytosis of non-opsonized microorganisms. This review describes the functional role of LacCer-enriched membrane microdomains and their interactions with CD11b/CD18.

  20. Arabidopsis cortical microtubules position cellulose synthase delivery to the plasma membrane and interact with cellulose synthase trafficking compartments.

    NARCIS (Netherlands)

    Gutierrez, R.; Lindeboom, J.J.; Paredez, A.R.; Emons, A.M.C.; Ehrhardt, D.W.

    2009-01-01

    Plant cell morphogenesis relies on the organization and function of two polymer arrays separated by the plasma membrane: the cortical microtubule cytoskeleton and cellulose microfibrils in the cell wall. Studies using in vivo markers confirmed that one function of the cortical microtubule array is

  1. Black Hole Area Quantization rule from Black Hole Mass Fluctuations

    OpenAIRE

    Schiffer, Marcelo

    2016-01-01

    We calculate the black hole mass distribution function that follows from the random emission of quanta by Hawking radiation and with this function we calculate the black hole mass fluctuation. From a complete different perspective we regard the black hole as quantum mechanical system with a quantized event horizon area and transition probabilities among the various energy levels and then calculate the mass dispersion. It turns out that there is a perfect agreement between the statistical and ...

  2. Ultra-high-density 3D DNA arrays within nanoporous biocompatible membranes for single-molecule-level detection and purification of circulating nucleic acids

    Science.gov (United States)

    Aramesh, M.; Shimoni, O.; Fox, K.; Karle, T. J.; Lohrmann, A.; Ostrikov, K.; Prawer, S.; Cervenka, J.

    2015-03-01

    alumina membrane. The few nanometer-thick, yet perfect and continuous DLC-coating confers the chemical stability and biocompatibility of the sensor, allowing its direct application in biological conditions. The selective detection is based on complementary hybridization of a fluorescently-tagged circulating cancer oncomarker (a 21-mer nucleic acid) with covalently immobilized DNA on the surface of the membrane. The captured DNAs are detected in the nanoporous structure of the sensor using confocal scanning laser microscopy. The flow-through membrane sensor demonstrates broad-range sensitivity, spanning from 1015 molecules per cm2 down to single molecules, which is several orders of magnitude improvement compared to the flat DNA microarrays. Our study suggests that these flow-through type nanoporous sensors represent a new powerful platform for large volume sampling and ultrasensitive detection of different chemical biomarkers. Electronic supplementary information (ESI) available: Time dependent fluorescence intensity measurements, photoluminescence decay on flat and nanoporous arrays, fluorophore time traces and photoluminescence of AAO and DLC-AAO. See DOI: 10.1039/c4nr07351g

  3. Fabrication and characterization of vertically aligned carbon-nanotube membranes

    Science.gov (United States)

    Castellano, Richard; Akin, Cevat; Purri, Matt; Shan, Jerry; Kim, Sangil; Fornasiero, Francesco

    2015-11-01

    Membranes having vertically-aligned carbon-nanotube (VACNT) pores offer promise as highly efficient and permeable membranes for use as breathable thin films, or in filtration and separation applications, among others. However, current membrane-fabrication techniques utilizing chemical-vapor-deposition-grown VACNT arrays are costly and difficult to scale up. We have developed a solution-based, electric-field-assisted approach as a cost-effective and scalable method to produce large-area VACNT membranes. Nanotubes are dispersed in a liquid polymer, and aligned and electrodeposited with the aid of an electric field prior to crosslinking the polymer to create VACNT membranes. We experimentally examine the electrodeposition process, focusing on parameters including the electric field, composition of the solution, and CNT functionalization that can affect the nanotube number density in the resulting membrane. We characterize the CNT pore size and number density and investigate the transport properties of the membrane. Size-exclusion tests are used to check for defects and infer the pore size of the VACNT membranes. Dry-gas membrane permeability is measured with a pressurized nitrogen-flow system, while moisture-vapor-transfer rate is measured with the ASTM-E96 upright-cup test. We discuss the measured transport properties of the solution-based, electric-field-fabricated VACNT membranes in reference to their application as breathable thin films. We would like to acknowledge DTRA for their funding and support of our research.

  4. Monopole Black Hole Skyrmions

    OpenAIRE

    Moss, Ian G; Shiiki, N; Winstanley, E

    2000-01-01

    Charged black hole solutions with pion hair are discussed. These can be\\ud used to study monopole black hole catalysis of proton decay.\\ud There also exist\\ud multi-black hole skyrmion solutions with BPS monopole behaviour.

  5. Comparison of pH Data Measured with a pH Sensor Array Using Different Data Fusion Methods

    OpenAIRE

    Yi-Hung Liao; Jung-Chuan Chou

    2012-01-01

    This paper introduces different data fusion methods which are used for an electrochemical measurement using a sensor array. In this study, we used ruthenium dioxide sensing membrane pH electrodes to form a sensor array. The sensor array was used for detecting the pH values of grape wine, generic cola drink and bottled base water. The measured pH data were used for data fusion methods to increase the reliability of the measured results, and we also compared the fusion results with other differ...

  6. Skyrmion black hole hair: Conservation of baryon number by black holes and observable manifestations

    Energy Technology Data Exchange (ETDEWEB)

    Dvali, Gia [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, 80333 München (Germany); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Gußmann, Alexander, E-mail: alexander.gussmann@physik.uni-muenchen.de [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, 80333 München (Germany)

    2016-12-15

    We show that the existence of black holes with classical skyrmion hair invalidates standard proofs that global charges, such as the baryon number, cannot be conserved by a black hole. By carefully analyzing the standard arguments based on a Gedankenexperiment in which a black hole is seemingly-unable to return the baryon number that it swallowed, we identify inconsistencies in this reasoning, which does not take into the account neither the existence of skyrmion black holes nor the baryon/skyrmion correspondence. We then perform a refined Gedankenexperiment by incorporating the new knowledge and show that no contradiction with conservation of baryon number takes place at any stage of black hole evolution. Our analysis also indicates no conflict between semi-classical black holes and the existence of baryonic gauge interaction arbitrarily-weaker than gravity. Next, we study classical cross sections of a minimally-coupled massless probe scalar field scattered by a skyrmion black hole. We investigate how the skyrmion hair manifests itself by comparing this cross section with the analogous cross section caused by a Schwarzschild black hole which has the same ADM mass as the skyrmion black hole. Here we find an order-one difference in the positions of the characteristic peaks in the cross sections. The peaks are shifted to smaller scattering angles when the skyrmion hair is present. This comes from the fact that the skyrmion hair changes the near horizon geometry of the black hole when compared to a Schwarzschild black hole with same ADM mass. We keep the study of this second aspect general so that the qualitative results which we obtain can also be applied to black holes with classical hair of different kind.

  7. Entropy of quasiblack holes

    International Nuclear Information System (INIS)

    Lemos, Jose P. S.; Zaslavskii, Oleg B.

    2010-01-01

    We trace the origin of the black hole entropy S, replacing a black hole by a quasiblack hole. Let the boundary of a static body approach its own gravitational radius, in such a way that a quasihorizon forms. We show that if the body is thermal with the temperature taking the Hawking value at the quasihorizon limit, it follows, in the nonextremal case, from the first law of thermodynamics that the entropy approaches the Bekenstein-Hawking value S=A/4. In this setup, the key role is played by the surface stresses on the quasihorizon and one finds that the entropy comes from the quasihorizon surface. Any distribution of matter inside the surface leads to the same universal value for the entropy in the quasihorizon limit. This can be of some help in the understanding of black hole entropy. Other similarities between black holes and quasiblack holes such as the mass formulas for both objects had been found previously. We also discuss the entropy for extremal quasiblack holes, a more subtle issue.

  8. Enhanced Performance of Photoelectrochemical Water Splitting with ITO@α-Fe2O3 Core-Shell Nanowire Array as Photoanode.

    Science.gov (United States)

    Yang, Jie; Bao, Chunxiong; Yu, Tao; Hu, Yingfei; Luo, Wenjun; Zhu, Weidong; Fu, Gao; Li, Zhaosheng; Gao, Hao; Li, Faming; Zou, Zhigang

    2015-12-09

    Hematite (α-Fe2O3) is one of the most promising candidates for photoelectrodes in photoelectrochemical water splitting system. However, the low visible light absorption coefficient and short hole diffusion length of pure α-Fe2O3 limits the performance of α-Fe2O3 photoelectrodes in water splitting. Herein, to overcome these drawbacks, single-crystalline tin-doped indium oxide (ITO) nanowire core and α-Fe2O3 nanocrystal shell (ITO@α-Fe2O3) electrodes were fabricated by covering the chemical vapor deposited ITO nanowire array with compact thin α-Fe2O3 nanocrystal film using chemical bath deposition (CBD) method. The J-V curves and IPCE of ITO@α-Fe2O3 core-shell nanowire array electrode showed nearly twice as high performance as those of the α-Fe2O3 on planar Pt-coated silicon wafers (Pt/Si) and on planar ITO substrates, which was considered to be attributed to more efficient hole collection and more loading of α-Fe2O3 nanocrystals in the core-shell structure than planar structure. Electrochemical impedance spectra (EIS) characterization demonstrated a low interface resistance between α-Fe2O3 and ITO nanowire arrays, which benefits from the well contact between the core and shell. The stability test indicated that the prepared ITO@α-Fe2O3 core-shell nanowire array electrode was stable under AM1.5 illumination during the test period of 40,000 s.

  9. Investigations on effects of the hole size to fix electrodes and interconnection lines in polydimethylsiloxane

    Science.gov (United States)

    Behkami, Saber; Frounchi, Javad; Ghaderi Pakdel, Firouz; Stieglitz, Thomas

    2017-11-01

    Translational research in bioelectronics medicine and neural implants often relies on established material assemblies made of silicone rubber (polydimethylsiloxane-PDMS) and precious metals. Longevity of the compound is of utmost importance for implantable devices in therapeutic and rehabilitation applications. Therefore, secure mechanical fixation can be used in addition to chemical bonding mechanisms to interlock PDMS substrate and insulation layers with metal sheets for interconnection lines and electrodes. One of the best ways to fix metal lines and electrodes in PDMS is to design holes in electrode rims to allow for direct interconnection between top to bottom layer silicone. Hence, the best layouts and sizes of holes (up to 6) which provide sufficient stability against lateral and vertical forces have been investigated with a variety of numbers of hole in line electrodes, which are simulated and fabricated with different layouts, sizes and materials. Best stability was obtained with radii of 100, 72 and 62 µm, respectively, and a single central hole in aluminum, platinum and MP35N foil line electrodes of 400  ×  500 µm2 size and of thickness 20 µm. The study showed that the best hole size which provides line electrode immobility (of thickness less than 30 µm) within a central hole is proportional to reverse value of Young’s Modulus of the material used. Thus, an array of line electrodes was designed and fabricated to study this effect. Experimental results were compared with simulation data. Subsequently, an approximation curve was generated as design rule to propose the best radius to fix line electrodes according to the material thickness between 10 and 200 µm using PDMS as substrate material.

  10. Plasmonic Photovoltaic Cells with Dual-Functional Gold, Silver, and Copper Half-Shell Arrays.

    Science.gov (United States)

    Wu, Ling; Kim, Gyu Min; Nishi, Hiroyasu; Tatsuma, Tetsu

    2017-09-12

    Solid-state photovoltaic cells based on plasmon-induced charge separation (PICS) have attracted growing attention during the past decade. However, the power conversion efficiency (PCE) of the previously reported devices, which are generally loaded with dispersed metal nanoparticles as light absorbers, has not been sufficiently high. Here we report simpler plasmonic photovoltaic cells with interconnected Au, Ag, and Cu half-shell arrays deposited on SiO 2 @TiO 2 colloidal crystals, which serve both as a plasmonic light absorber and as a current collector. The well-controlled and easily prepared plasmonic structure allows precise comparison of the PICS efficiency between different plasmonic metal species. The cell with the Ag half-shell array has higher photovoltaic performance than the cells with Au and Cu half-shell arrays because of the high population of photogenerated energetic electrons, which gives a high electron injection efficiency and suppressed charge recombination probability, achieving the highest PCE among the solid-state PICS devices even without a hole transport layer.

  11. Black holes without firewalls

    Science.gov (United States)

    Larjo, Klaus; Lowe, David A.; Thorlacius, Larus

    2013-05-01

    The postulates of black hole complementarity do not imply a firewall for infalling observers at a black hole horizon. The dynamics of the stretched horizon, that scrambles and reemits information, determines whether infalling observers experience anything out of the ordinary when entering a large black hole. In particular, there is no firewall if the stretched horizon degrees of freedom retain information for a time of the order of the black hole scrambling time.

  12. The effect of particle-hole interaction on the XPS core-hole spectrum

    International Nuclear Information System (INIS)

    Ohno, Masahide; Sjoegren, Lennart

    2004-01-01

    How the effective particle-hole interaction energy, U, or the polarization effect on a secondary electron in a final two-hole one-particle (2h1p) state created by the Coster-Kronig (CK) transition can solely affect the density of the CK particle states and consequently the core-hole spectral function, is discussed. The X-ray photoelectron spectroscopy (XPS) core-hole spectrum is predominantly governed by the unperturbed initial core-hole energy relative to the zero-point energy. At the latter energy, the real part of the initial core-hole self-energy becomes zero (no relaxation energy shift) and the imaginary part (the lifetime broadening) approximately maximizes. The zero-point energy relative to the double-ionization threshold energy is governed by the ratio of U relative to the bandwidth of the CK continuum. As an example, we study the 5p XPS spectra of atomic Ra (Z=88), Th (Z=90) and U (Z=92). The spectra are interpreted in terms of the change in the unperturbed initial core-hole energy relative to the zero-point energy. We explain why in general an ab initio atomic many-body calculation can provide an overall good description of solid-state spectra predominantly governed by the atomic-like localized core-hole dynamics. We explain this in terms of the change from free atom to metal in both U and the zero-point energy (self-energy)

  13. Over spinning a black hole?

    Energy Technology Data Exchange (ETDEWEB)

    Bouhmadi-Lopez, Mariam; Cardoso, Vitor; Nerozzi, Andrea; Rocha, Jorge V, E-mail: mariam.bouhmadi@ist.utl.pt, E-mail: vitor.cardoso@ist.utl.pt, E-mail: andrea.nerozzi@ist.utl.pt, E-mail: jorge.v.rocha@ist.utl.pt [CENTRA, Department de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049 Lisboa (Portugal)

    2011-09-22

    A possible process to destroy a black hole consists on throwing point particles with sufficiently large angular momentum into the black hole. In the case of Kerr black holes, it was shown by Wald that particles with dangerously large angular momentum are simply not captured by the hole, and thus the event horizon is not destroyed. Here we reconsider this gedanken experiment for black holes in higher dimensions. We show that this particular way of destroying a black hole does not succeed and that Cosmic Censorship is preserved.

  14. Causal hydrodynamics and the membrane paradigm

    International Nuclear Information System (INIS)

    Natsuume, Makoto

    2008-01-01

    We obtain the relaxation time for the shear viscous stress for various geometries using the 'membrane paradigm' formula proposed recently. We consider the generic Schwarzschild-anti-de Sitter black holes (SAdS), the generic Dp-brane, the Klebanov-Tseytlin (KT) geometry, and the N=2* theory. The formula is the 'shear mode' result and is not fully trustable, but it may be helpful to learn some generic behaviors about the relaxation time. For example, a simple formula summarizes all known results for SAdS, and a single expression summarizes the results for the Dp-brane and the KT geometry.

  15. Swift heavy ion induced modification in polycarbonate membrane for gas separation

    International Nuclear Information System (INIS)

    Rajesh Kumar; Prasad, Rajendra; Vijay, Y.K.; Das, D.

    2003-01-01

    Polymeric membranes are extensively used for commercial gas separation applications. Makrofol-KG (polycarbonate) is a glassy polymer. 40 μm thick sheet of Makrofol-KG was irradiated with 40 Ar (14.9 MeV/n) of fluence 10 3 ions/cm 2 and 20 μm thick sheet with 5.3 MeV α-particles of fluence 10 7 ions/cm 2 . The permeability of these polycarbonate membranes for H 2 and CO 2 was measured and also after etching in 6 N NaOH at 60 degC for different periods. Permeability is found to be increased with etching time. At a definite time, critical etching time, the permeability rapidly increases in PC. Positron annihilation lifetimes for unirradiated and irradiated membranes were measured with fast fast coincidence system to study the correlation of free volume hole concentration with gas separation properties. (author)

  16. Quasi-hexagonal vortex-pinning lattice using anodized aluminum oxide nanotemplates

    DEFF Research Database (Denmark)

    Hallet, X.; Mátéfi-Tempfli, M.; Michotte, S.

    2009-01-01

    The bottom barrier layer of well-ordered nanoporous alumina membranes reveals a previously unexploited nanostructured template surface consisting of a triangular lattice of hemispherical nanoscale bumps. Quasi-hexagonal vortex-pinning lattice arrays are created in superconducting Nb films deposited...... onto this template (see image). Matching effects are preserved at higher magnetic fields and lower temperatures when compared to holes on the top face....

  17. Accreting Black Holes

    OpenAIRE

    Begelman, Mitchell C.

    2014-01-01

    I outline the theory of accretion onto black holes, and its application to observed phenomena such as X-ray binaries, active galactic nuclei, tidal disruption events, and gamma-ray bursts. The dynamics as well as radiative signatures of black hole accretion depend on interactions between the relatively simple black-hole spacetime and complex radiation, plasma and magnetohydrodynamical processes in the surrounding gas. I will show how transient accretion processes could provide clues to these ...

  18. Naked black holes

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Ross, S.F.

    1997-01-01

    It is shown that there are large static black holes for which all curvature invariants are small near the event horizon, yet any object which falls in experiences enormous tidal forces outside the horizon. These black holes are charged and near extremality, and exist in a wide class of theories including string theory. The implications for cosmic censorship and the black hole information puzzle are discussed. copyright 1997 The American Physical Society

  19. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs.

  20. MFM observations of domain wall creep and pinning effects in amorphous CoxSi1-x films with diluted arrays of antidots

    International Nuclear Information System (INIS)

    Rodriguez-Rodriguez, G; Perez-Junquera, A; Velez, M; Anguita, J V; Martin, J I; Rubio, H; Alameda, J M

    2007-01-01

    Magnetic force microscopy (MFM) has been used to analyse the behaviour of domain walls in uniaxial amorphous Co x Si 1-x films patterned with diluted arrays of antidots by electron beam lithography. The walls are found to be pinned by the antidot array when the antidot density is high enough along the easy axis. The expansion of reversed nuclei under the influence of the tip stray field has been observed in several consecutive MFM images of the same area, showing how the competition between line tension effects and pinning by the patterned holes governs the creep motion of the 180 0 walls across the array of antidots