Sample records for su-8 negative photoresist

  1. SU-8 negative photoresist for optical mask manufacturing (United States)

    Bogdanov, Alexei L.


    The requirements for better control, linearity, and uniformity of critical dimension (CD) on photomasks in fabrication of 180 and 150 nm generation devices result in increasing demand for thinner, more etching durable, and more sensitive e-beam resists. Novolac based resists with chemical amplification have been a choice for their sensitivity and stability during etching. However, difficult CD control due to the acid catalyzer diffusion and quite narrow post exposure bake (PEB) process window are some of the major drawbacks of these resists. SU-8 is recently introduced to the market negative photoresist. High sensitivity, fairly good adhesion properties, and relatively simple processing of SU-8 make it a good substitution for novolac based chemically amplified negative e-beam resists in optical mask manufacturing. The replacement of traditional chemically amplified resists by SU- 8 can increase the process latitude and reduce resist costs. Among the obvious drawbacks of SU-8 are the use of solvent- based developer and demand of oxygen plasma for resist removal. In this paper the use of SU-8 for optical mask manufacturing is reported. All steps of resist film preparation, exposure and development are paid a share of attention. Possibilities to use reactive ion etching (RIE) with oxygen in order to increase resist mask contrast are discussed. Special exposure strategy (pattern outlining) was employed to further improve the edge definition. The resist PEB temperature and time were studied to estimate their weight in overall CD control performance. Specially designed test patterns with 0.25 micrometer design rule could be firmly transferred into a chromium layer both by wet etching and ion milling. Influence of exposure dose variation on the pattern CD change was studied.

  2. Volume Hologram Formation in SU-8 Photoresist

    Directory of Open Access Journals (Sweden)

    Tina Sabel


    Full Text Available In order to further understand the mechanism of volume hologram formation in photosensitive polymers, light-induced material response is analyzed in commonly used epoxy-based negative photoresist Epon SU-8. For this purpose, time-resolved investigation of volume holographic grating growth is performed in the SU-8 based host–guest system and in the pure SU-8 material, respectively. The comparison of grating growth curves from doped and undoped system allows us to draw conclusions on the impact of individual components on the grating formation process. The successive formation of transient absorption as well as phase gratings in SU-8 is observed. Influence of exposure duration and UV flood cure on the grating growth are investigated. Observed volume holographic grating formation in SU-8 can be explained based on the generation and subsequent diffusion of photoacid as well as time-delayed polymerization of exposed and unexposed areas.

  3. Functionalization of SU-8 Photoresist Surfaces with IgG Proteins

    DEFF Research Database (Denmark)

    Blagoi, Gabriela; Keller, Stephan Urs; Johansson, Alicia


    The negative epoxy-based photoresist SU-8 has a variety of applications within microelectromechanical systems (MEMS) and lab-on-a-chip systems. Here, several methods to functionalize SU-8 surfaces with IgG proteins were investigated. Fluorescent labeled proteins and fluorescent sandwich immunoass......The negative epoxy-based photoresist SU-8 has a variety of applications within microelectromechanical systems (MEMS) and lab-on-a-chip systems. Here, several methods to functionalize SU-8 surfaces with IgG proteins were investigated. Fluorescent labeled proteins and fluorescent sandwich...... SU-8 in a functional fluorescent sandwich immunoassay detecting C-reactive protein (CRP) gave twice as high signal as compared with the other two surfaces. Immunoassays performed on bare SU-8 and CAN treated SU-8 resulted in detection limits of CRP of 30 and 80 ng/ml respectively which is sufficient...

  4. Novel method for chemical modification and patterning of the SU-8 photoresist

    DEFF Research Database (Denmark)

    Blagoi, Gabriela; Keller, Stephan Urs; Boisen, Anja


    In this paper we describe a new photochemical method to tailor and pattern the surface of SU-8 negative photoresist. Antraquinone (AQ) derivatives were used to chemically modify and pattern SU-8 surfaces. Using AQ derivatives with electophilic moieties (AQ-E), we could chemo-selectively change...... the wetting behaviour of SU-8. The resolution limit of the AQ photopatterning method was 20 μm when using an uncollimated light source. AQ modification followed by a reaction with amino groups of Alexa-647 cadaverine and a Biotin-amino derivative proved possible modification and patterning of polymeric...

  5. Using an SU-8 Photoresist Structure and Cytochrome C Thin Film Sensing Material for a Microbolometer

    Directory of Open Access Journals (Sweden)

    Guo-Dung John Su


    Full Text Available There are two critical parameters for microbolometers: the temperature coefficient of resistance (TCR of the sensing material, and the thermal conductance of the insulation structure. Cytochrome c protein, having a high TCR, is a good candidate for infrared detection. We can use SU-8 photoresist for the thermal insulation structure, given its low thermal conductance. In this study, we designed a platform structure based on a SU-8 photoresist. We fabricated an infrared sensing pixel and recorded a high TCR for this new structure. The SU-8 photoresist insulation structure was fabricated using the exposure dose method. We experimentally demonstrated high values of TCR from 22%/K to 25.7%/K, and the measured noise was 1.2 × 10–8 V2/Hz at 60 Hz. When the bias current was 2 μA, the calculated voltage responsivity was 1.16 × 105 V/W. This study presents a new kind of microbolometer based on cytochrome c protein on top of an SU-8 photoresist platform that does not require expensive vacuum deposition equipment.

  6. Using an SU-8 photoresist structure and cytochrome C thin film sensing material for a microbolometer. (United States)

    Lai, Jian-Lun; Liao, Chien-Jen; Su, Guo-Dung John


    There are two critical parameters for microbolometers: the temperature coefficient of resistance (TCR) of the sensing material, and the thermal conductance of the insulation structure. Cytochrome c protein, having a high TCR, is a good candidate for infrared detection. We can use SU-8 photoresist for the thermal insulation structure, given its low thermal conductance. In this study, we designed a platform structure based on a SU-8 photoresist. We fabricated an infrared sensing pixel and recorded a high TCR for this new structure. The SU-8 photoresist insulation structure was fabricated using the exposure dose method. We experimentally demonstrated high values of TCR from 22%/K to 25.7%/K, and the measured noise was 1.2 × 10(-8) V2/Hz at 60 Hz. When the bias current was 2 μA, the calculated voltage responsivity was 1.16 × 10(5) V/W. This study presents a new kind of microbolometer based on cytochrome c protein on top of an SU-8 photoresist platform that does not require expensive vacuum deposition equipment.

  7. A study of SU-8 photoresist in deep trenches for silicon-embedded microinductors (United States)

    Laforge, Elias; Rabot, Caroline; Wang, Ningning; Pavlovic, Zoran; McCloskey, Paul; O'Mathúna, Cian


    Epoxy-based resist SU-8 is widely used in the development and fabrication of high-aspect-ratio (HAR) MEMS structures. It has proven to be a suitable photoresist combining thick layer coating and good adhesion on silicon substrates as well as possessing good mechanical and chemical stability. However, the trend towards minia- turization and increasing packaging density has pushed the demand for challenging micro-machining processes. As an example, a novel design of a MEMS microinductor requires a dielectric permanent layer coated in deep silicon trenches in order to insulate copper windings from the magnetic material deposited in these trenches. This requires the development of a photolithography process which enables the coating of a void-free layer filling the trenches. In this paper, the use of thick SU-8 photoresist for filling deep silicon trenches is investigated. Different SU-8 formulations are analyzed, processed and results are compared. As a result, an optimized process is developed to achieve void-free filled trenches and a uniform planar layer above them, with near vertical sidewall patterns.

  8. A superhydrophobic chip based on SU-8 photoresist pillars suspended on a silicon nitride membrane

    KAUST Repository

    Marinaro, Giovanni


    We developed a new generation of superhydrophobic chips optimized for probing ultrasmall sample quantities by X-ray scattering and fluorescence techniques. The chips are based on thin Si3N4 membranes with a tailored pattern of SU-8 photoresist pillars. Indeed, aqueous solution droplets can be evaporated and concentrated at predefined positions using a non-periodic pillar pattern. We demonstrated quantitatively the deposition and aggregation of gold glyconanoparticles from the evaporation of a nanomolar droplet in a small spot by raster X-ray nanofluorescence. Further, raster nanocrystallography of biological objects such as rod-like tobacco mosaic virus nanoparticles reveals crystalline macro-domain formation composed of highly oriented nanorods. © 2014 the Partner Organisations.

  9. UV-LIGA Microfabrication of 220 GHz Sheet Beam Amplifier Gratings with SU-8 Photoresists (United States)


    etching (DRIE) is not effective on copper substrates, but was used to fabricate metalized silicon test pieces [11]. This paper begins with a detailed...figure 9(b)). After an ultrasonic bath in Microclean 90 R© and water, only half of a dozen blackened bits of SU-8 remained. The remaining SU-8 residue... metallization Master of Science Thesis Dept of Chem. Eng., Case Western Reserve University [22] Pasquale M A, Gassa L M and Arvia A J 2008 Copper


    Miller, Eric; Ellis, Daniel; Charles, Duran; McKenzie, Jason


    A materials fabrication study of a photodiode array for possible application of retina prosthesis was undertaken. A test device was fabricated using a glassy carbon electrode patterned with SU-8 photoresist. In the openings, p-type polypyrrole was first electrodeposited using 1-butyl-1-methylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid. The polypyrrole was self-doped with imide ion at ~1.5 mole %, was verified as p-type, and had a resistivity of ~20 Ωcm. N-type Silicon was then electrodeposited over this layer using silicon tetrachloride / phosphorus trichloride in acetonitrile and passivated in a second electrodeposition using trimethylchlorosilane. Electron microscopy revealed the successful electrodeposition of silicon over patterned polypyrrole. Rudimentary photodiode behavior was observed. The passivation improved but did not completely protect the electrodeposited silicon from oxidation by air.

  11. Tailoring the mechanical properties of SU-8/clay nanocomposites: polymer microcantilever fabrication perspective

    CSIR Research Space (South Africa)

    Chen, H


    Full Text Available SU-8/Clay nanocomposite is considered as a candidate material for microcantilever sensor fabrication. Organically modified montmorillonite clay nanoparticles are dispersed in the universally used negative photoresist polymer SU-8, for a low cost...

  12. Negative-tone cycloolefin photoresist for 193-nm lithography (United States)

    Fu, ShihChi; Hsieh, Kuo-Huang; Wang, Lon A.


    The chemistry of acid-catalyzed dehydration reaction and followed by crosslinking of the tert-alcohol group in the cycloolefin photoresists was used to tailor the performance of the photoresists for 193nm lithography. A radiation- sensitive photoacid generator (PAG) in this chemically amplified photoresist (CAMP) can change the polarity of the exposed area of the resist and exhibit a negative-tone behavior. The cycloolefin resists are synthesized by the free radical copolymerization of alicyclic monomer and maleic anhydride, and/or by the cationic polymerization of alicyclic monomer via Pd catalyst followed by the attaching of tert-alcohol group in to the resist. The side reaction of cycloolefin copolymer was observed at the temperature below the post exposure baking (PEB) temperature, but this problem can be eliminated by the introduction of isobornyl methacrylate into the polymer. The lithographic performance of the resists was investigated by using isopropyl alcohol as a developer under various processing conditions. The results demonstrate that these resists are the promising candidates for being used in 193nm lithography.

  13. Spray-coatable negative photoresist for high topography MEMS applications (United States)

    Arnold, Markus; Voigt, Anja; Haas, Sven; Schwenzer, Falk; Schwenzer, Gunther; Reuter, Danny; Gruetzner, Gabi; Geßner, Thomas


    In microsystem technology, the lithographical processing of substrates with a topography is very important. Interconnecting lines, which are routed over sloped topography sidewalls from the top of the protecting wafer to the contact pads of the device wafer, are one example of patterning over a topography. For structuring such circuit paths, a photolithography process, and therefore a process for homogeneous photoresist coating, is required. The most flexible and advantageous way of depositing a homogeneous photoresist film over structures with high topography steps is spray-coating. As a pattern transfer process for circuit paths in cavities, the lift-off process is widely used. A negative resist, like ma-N (MRT) or AZnLOF (AZ) is favoured for lift-off processes due to the existing negative angle of the sidewalls. Only a few sprayable negative photoresists are commercially available. In this paper, the development of a novel negative resist spray-coating based on a commercially available single-layer lift-off resist for spin-coating, especially for the patterning of structures inside the cavity and on the cavity wall, is presented. A variety of parameters influences the spray-coating process, and therefore the patterning results. Besides the spray-coating tool and the parameters, the composition of the resist solution itself also influences the coating results. For homogeneous resist coverage over the topography of the substrate, different solvent combinations for diluting the resist solution, different chuck temperatures during the coating process, and also the softbake conditions, are all investigated. The solvent formulations and the process conditions are optimized with respect to the homogeneity of the resist coverage on the top edge of the cavities. Finally, the developed spray-coating process, the resist material and the process stability are demonstrated by the following applications: (i) lift-off, (ii) electroplating, (iii) the wet and (iv) the dry

  14. Exposure parameters in proton beam writing for KMPR and EPO Core negative tone photoresists

    Energy Technology Data Exchange (ETDEWEB)

    Ynsa, M.D., E-mail: [Centro de Micro-Analisis de Materiales (CMAM), Universidad Autonoma de Madrid, Campus de Cantoblanco Edif. 22, Faraday 3, E-28049 Madrid (Spain); Departamento de Fisica Aplicada C-12, Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Shao, P.; Kulkarni, S.R.; Liu, N.N.; Kan, J.A. van [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore ,117542 Singapore (Singapore)


    In spite of its recent establishment, proton beam writing (PBW) has already demonstrated to be a highly competitive lithographic technique. PBW is a fast direct-write technique capable of producing high-aspect-ratio micro- and nano-structures in resist material. Typical applications can be found in nanoimprinting, biomedical research, photonics, and optics, among other fields. The progress of PBW is linked to the successful introduction of new resist materials. In this paper, KMPR and EPO Core, negative tone photoresists are tested on their compatibility with PBW. KMPR resist has similar chemical and process properties compared to SU-8. Employing UV lithography on KMPR resist, details of 30 {mu}m have been obtained in Ni, indicating a possible advantage compared to SU-8 for optical lithography . In this study, the sensitivity to MeV proton exposure and sub-micron feature sizes are presented in KMPR. PBW has been also combined with Ni electroplating in order to determine the suitability of KMPR and EPO Core resist to fabricate 3D metallic moulds and stamps.

  15. Special Issue: 15 Years of SU8 as MEMS Material

    Directory of Open Access Journals (Sweden)

    Arnaud Bertsch


    Full Text Available In 1997, the first paper using SU-8 as a material for microfabrication was published [1], demonstrating the interest of this negative photoresist for the near-UV structuration of thick layers and the manufacturing of high aspect-ratio components.[...

  16. Kinetic study of negative dry-film photoresists

    Directory of Open Access Journals (Sweden)


    Full Text Available Thanks to the differential photocalorimetry technique DPC, characteristics of negative photoresists (Riston® PM 215 and Riston® MM 140, 1 mil or 25.4 µm thickness to be developed in nonorganic aqueous medium used in microlithography are highlighted. The photoreactivity (being evaluated by DPC of the matrix polymer involved in these Riston® is critical for ensuring good lithographic performance. The influence of temperature and irradiation intensity on kinetic parameters such as the enthalpy of reaction ΔH, the time of induction (It, the conversion rate to the maximum peak (RPM, the coefficient rate of the reaction (k, the conversion rate α, and the polymerization rate Rp were studied. All the results highlights not only the strong differences between the two Riston® studied, but also the great reactivity of Riston® PM 215 compared to Riston® MM 140.

  17. Innovative SU-8 Lithography Techniques and Their Applications

    Directory of Open Access Journals (Sweden)

    Jeong Bong Lee


    Full Text Available SU-8 has been widely used in a variety of applications for creating structures in micro-scale as well as sub-micron scales for more than 15 years. One of the most common structures made of SU-8 is tall (up to millimeters high-aspect-ratio (up to 100:1 3D microstructure, which is far better than that made of any other photoresists. There has been a great deal of efforts in developing innovative unconventional lithography techniques to fully utilize the thick high aspect ratio nature of the SU-8 photoresist. Those unconventional lithography techniques include inclined ultraviolet (UV exposure, back-side UV exposure, drawing lithography, and moving-mask UV lithography. In addition, since SU-8 is a negative-tone photoresist, it has been a popular choice of material for multiple-photon interference lithography for the periodic structure in scales down to deep sub-microns such as photonic crystals. These innovative lithography techniques for SU-8 have led to a lot of unprecedented capabilities for creating unique micro- and nano-structures. This paper reviews such innovative lithography techniques developed in the past 15 years or so.

  18. SU-8 cantilever chip interconnection

    DEFF Research Database (Denmark)

    Johansson, Alicia Charlotte; Janting, Jakob; Schultz, Peter


    The polymer SU-8 is becoming widely used for all kinds of micromechanical and microfluidic devices, not only as a photoresist but also as the constitutional material of the devices. Many of these polymeric devices need to include a microfluidic system as well as electrical connection from...... the electrodes on the SU-8 chip to a printed circuit board. Here, we present two different methods of electrically connecting an SU-8 chip, which contains a microfluidic network and free-hanging mechanical parts. The tested electrical interconnection techniques are flip chip bonding using underfill or flip chip...... bonding using an anisotropic conductive film (ACF). These are both widely used in the Si industry and might also be used for the large scale interconnection of SU-8 chips. The SU-8 chip, to which the interconnections are made, has a microfluidic channel with integrated micrometer-sized cantilevers...

  19. Diffusion of water into SU-8 microcantilevers

    DEFF Research Database (Denmark)

    Liu, C.J.; Liu, Y.; Sokuler, M.


    We present a method to monitor the diffusion of liquid molecules in polymers. A microdrop of water is deposited by a piezoelectric drop generator onto the upper surface of a cantilever made of SU-8 based photoresist. In response, the cantilever bends in the opposite direction. We find that this b...... sophisticated finite element model the diffusion coefficient of water in the SU-8 polymer can be determined quantitatively from the dynamics of cantilever bending.......We present a method to monitor the diffusion of liquid molecules in polymers. A microdrop of water is deposited by a piezoelectric drop generator onto the upper surface of a cantilever made of SU-8 based photoresist. In response, the cantilever bends in the opposite direction. We find...... that this bending is mainly caused by the diffusion of water into the cantilever and the consequent swelling of SU-8. Using a one-dimensional diffusion model and assuming a simple swelling law, we qualitatively model the bending of the cantilever during in and out diffusion of water in SU-8. With a more...

  20. Chemically amplified negative-tone photoresist for sub-half-micron device and mask fabrication (United States)

    Conley, Will; Dundatscheck, Robert; Gelorme, Jeffrey D.; Horvat, John; Martino, Ronald M.; Murphy, Elizabeth; Petrosky, Anne; Spinillo, Gary T.; Stewart, Kevin J.; Wilbarg, Robert; Wood, Robert L.


    In this paper we discuss a new alkaline soluble negative acting photoresist which incorporates a phenolic based resin, urea/formaldehyde prepolymer as a crosslinking agent and an organic acid-generating sensitizer. This system, dubbed 'EBX' (Electron Beam/X-ray) resist has demonstrated excellent lithographic properties in various exposure modes. Discussion will center on imaging characteristics in the deep and mid ultraviolet using Micrascan I and I-line (365 nm) steppers; electron-beam imaging with MEBES 10 kV mask maker and IBM's EL-4 50 kV electron beam exposure system; and XRAY imaging with point source soft x-ray and synchotron hard x-ray lithography.

  1. High temperature SU-8 pyrolysis for fabrication of carbon electrodes

    DEFF Research Database (Denmark)

    Hassan, Yasmin Mohamed; Caviglia, Claudia; Hemanth, Suhith


    spectroscopy and Raman spectroscopy were used to characterize the pyrolytic carbon. The results show that the temperature increase from 900 °C to 1100 °C improves the electrical and electrochemical properties. At 1100 °C, longer dwell time leads to lower resistivity, while the variation of the pyrolysis...... composite experimental design was used to identify the influence of dwell time at the highest pyrolysis temperature and heating rate on electrical, electrochemical and structural properties of the pyrolytic carbon: Van der Pauw sheet resistance measurements, cyclic voltammetry, electrochemical impedance......In this work, we present the investigation of the pyrolysis parameters at high temperature (1100 °C) for the fabrication of two-dimensional pyrolytic carbon electrodes. The electrodes were fabricated by pyrolysis of lithographically patterned negative epoxy based photoresist SU-8. A central...

  2. Performance evaluation of nonchemically amplified negative tone photoresists for e-beam and EUV lithography (United States)

    Singh, Vikram; Satyanarayana, Vardhineedi Sri Venkata; Batina, Nikola; Reyes, Israel Morales; Sharma, Satinder K.; Kessler, Felipe; Scheffer, Francine R.; Weibel, Daniel E.; Ghosh, Subrata; Gonsalves, Kenneth E.


    Although extreme ultraviolet (EUV) lithography is being considered as one of the most promising next-generation lithography techniques for patterning sub-20 nm features, the development of suitable EUV resists remains one of the main challenges confronting the semiconductor industry. The goal is to achieve sub-20 nm line patterns having low line edge roughness (LER) of <1.8 nm and a sensitivity of 5 to 20 mJ/cm2. The present work demonstrates the lithographic performance of two nonchemically amplified (n-CARs) negative photoresists, MAPDST homopolymer and MAPDST-MMA copolymer, prepared from suitable monomers containing the radiation sensitive sulfonium functionality. Investigations into the effect of several process parameters are reported. These include spinning conditions to obtain film thicknesses <50 nm, baking regimes, exposure conditions, and the resulting surface topographies. The effect of these protocols on sensitivity, contrast, and resolution has been assessed for the optimization of 20 nm features and the corresponding LER/line width roughness. These n-CARs have also been found to possess high etch resistance. The etch durability of MAPDST homopolymer and MAPDST-MMA copolymer (under SF6 plasma chemistry) with respect to the silicon substrate are 7.2∶1 and 8.3∶1, respectively. This methodical investigation will provide guidance in designing new resist materials with improved efficiency for EUVL through polymer microstructure engineering.

  3. Moisture resistance of SU-8 and KMPR as structural material

    NARCIS (Netherlands)

    Blanco Carballo, V.M.; Melai, J.; Salm, Cora; Schmitz, Jurriaan


    This paper treats the moisture resistance of SU-8 and KMPR, two photoresists considered as structural material in microsystems. Our experiments focus on the moisture resistance of newly developed radiation imaging detectors containing these resists. Since these microsystems will be used unpackaged,

  4. A facile micropatterning method for a highly flexible PEDOT:PSS on SU-8

    KAUST Repository

    Cho, Nam Chul


    We report the micropatterning of conducting polymer on the epoxy-based photoresist to demonstrate fully organic, conducting and flexible electrodes. We show that polystyrene sulfonic acid can be covalently linked to the surface of the photoresist (SU-8) by forming sulfonyl ester at the interfaces. We also present an application of the patterned PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate)/SU-8 to the electroplating of metal electrodes. © 2016 Elsevier B.V.

  5. Surface chemical functionalisation of epoxy photoresist-based microcantilevers with organic-coated TiO2 nanocrystals

    DEFF Research Database (Denmark)

    Ingrosso, C.; Sardella, E.; Keller, S. S.


    In this Letter, a solution-based approach has been used for chemically immobilising oleic acid (OLEA)-capped TiO2 nanocrystals (NCs) on the surface of microcantilevers formed of SU-8, a negative tone epoxy photoresist. The immobilisation has been carried out at room temperature, under visible lig...

  6. A Simple Hydrophilic Treatment of SU-8 Surfaces for Cell Culturing and Cell Patterning

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Stangegaard, Michael; Dufva, Hans Martin


    SU-8, an epoxy-based photoresist, widely used in constitution different mTAS systems, is incompatible with mammalian cell adhesion and culture in its native form. Here, we demonstrate a simple, cheap and robust two-step method to render a SU-8 surface hydrophilic and compatible with cell culture...

  7. SU-8 photoresist-derived electrospun carbon nanofibres as high ...

    Indian Academy of Sciences (India)

    Author Affiliations. M KAKUNURI1 S KAUSHIK1 A SAINI1 C S SHARMA1. Creative and Advanced Research Based On Nanomaterials (CARBON) Laboratory, Department of Chemical Engineering, Indian Institute of Technology, Hyderabad, Kandi 502285, India ...

  8. SU-8 photoresist-derived electrospun carbon nanofibres as high ...

    Indian Academy of Sciences (India)


    Jun 9, 2017 ... Carbon nanofibres (CNF), due to their advantages like large surface area and thus enhanced interface of electrolyte and active material surface, short Li ion transport distances and high resilience to volume expansion during cycling even at high current densities, have drawn a great attention for being used ...

  9. Performance of SU-8 Membrane Suitable for Deep X-Ray Grayscale Lithography

    Directory of Open Access Journals (Sweden)

    Harutaka Mekaru


    Full Text Available In combination with tapered-trench-etching of Si and SU-8 photoresist, a grayscale mask for deep X-ray lithography was fabricated and passed a 10-times-exposure test. The performance of the X-ray grayscale mask was evaluated using the TERAS synchrotron radiation facility at the National Institute of Advanced Industrial Science and Technology (AIST. Although the SU-8 before photo-curing has been evaluated as a negative-tone photoresist for ultraviolet (UV and X-ray lithographies, the characteristic of the SU-8 after photo-curing has not been investigated. A polymethyl methacrylate (PMMA sheet was irradiated by a synchrotron radiation through an X-ray mask, and relationships between the dose energy and exposure depth, and between the dose energy and dimensional transition, were investigated. Using such a technique, the shape of a 26-μm-high Si absorber was transformed into the shape of a PMMA microneedle with a height of 76 μm, and done with a high contrast. Although during the fabrication process of the X-ray mask a 100-μm-pattern-pitch (by design was enlarged to 120 μm. However, with an increase in an integrated dose energy this number decreased to 99 μm. These results show that the X-ray grayscale mask has many practical applications. In this paper, the author reports on the evaluation results of SU-8 when used as a membrane material for an X-ray mask.

  10. Immunosensing by luminescence reduction in surface-modified microstructured SU-8

    Energy Technology Data Exchange (ETDEWEB)

    Eravuchira, Pinkie Jacob; Baranowska, Malgorzata; Eckstein, Chris [Departament d’Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda. Països Catalans 26, Tarragona 43007 (Spain); Díaz, Francesc [Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcelí Domingo s/n, Tarragona 43007 (Spain); Llobet, Eduard; Marsal, Lluis F. [Departament d’Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda. Països Catalans 26, Tarragona 43007 (Spain); Ferré-Borrull, Josep, E-mail: [Departament d’Enginyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda. Països Catalans 26, Tarragona 43007 (Spain)


    Highlights: • The reduction of photoluminescence of SU-8 upon surface modification is reported. • Micropillar structuring of SU-8 surface results in an increased photoluminescence reduction rate (10% glass, 15% silicon). • Photoluminescence reduction rate can be a transduction parameter for the detection of antibody-antigen binding events. • The proposed sensing mechanism can be used to quantify small concentrations of antibody. • Lower limit of detection (LOD) of 28 μg/ml on silicon substrates and 42 μg/ml on glass substrates was achieved. - Abstract: SU-8, an epoxy based negative photoresist is extensively used as a structural material for the fabrication of microelectro-mechanical systems and in microelectronics technology. However, the possible applications of SU-8 for biosensing have not been explored much, mainly because of the photoluminescence SU-8 possesses in the near-UV and visible wavelength ranges which hinders fluorescent labelling of biorecognition events. In this study we demonstrate that photoluminescence of SU-8 can be employed itself as a sensing transduction parameter to produce a tool for immunosensing: the photoluminescence shows a systematic reduction upon modification of its surface chemistry, and in particular upon attachment of an antigen-antibody (aIgG-IgG) pair. We investigate the relation of the amount of reduction of photoluminescence on planar and microstructured surfaces, and we show that microstructuring leads to a higher reduction than a planar surface. Furthermore, we evaluated the dependence of photoluminescence reduction as a function of analyte concentration to prove that this magnitude can be applied to immunosensing.

  11. SU-8 microfluidic device for scintillating particle detection

    CERN Document Server

    Mapelli, A; Haguenauer, M; Jiguet, S; Vico Triviño, N; Renaud, P


    This paper presents the study of a novel scintillation detector based on standard microfabrication techniques. It consists of a fine pitch array of hollow waveguides filled with a liquid scintillator and optically coupled to photodetectors. The detector has been fabricated by patterning the SU-8 photoresist on silicon wafers. Experimental studies have been performed by exciting the liquid scintillator contained in the SU-8 waveguides with electrons. The scintillation light produced was read out by an external photodetector. The results obtained with this set-up demonstrate the concept of microfluidic scintillation detection and are very encouraging for future developments.

  12. KMPR Photoresist Process Optimization Using Factorial Experimental Design

    National Research Council Canada - National Science Library

    Miller, Harris R; Johnson, Donald W; Mori, Satoshi


    .... This chemically amplified thick-film photoresist, known as KMPR, has many of the same high-aspect ratio photo imaging properties as solvent developable SU-8, but can be developed in a conventional...

  13. A Simple Hydrophilic Treatment of SU-8 Surfaces for Cell Culturing and Cell Patterning

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Stangegaard, Michael; Dufva, Hans Martin


    SU-8, an epoxy-based photoresist, widely used in constitution different mTAS systems, is incompatible with mammalian cell adhesion and culture in its native form. Here, we demonstrate a simple, cheap and robust two-step method to render a SU-8 surface hydrophilic and compatible with cell culture........ The contact angle of SU-8 surface was significantly reduced from 90° to 25° after the surface modification. The treated SU-8 surfaces provided a cell culture environment that was comparable with cell culture flask surface in terms of generation time and morphology....

  14. PMMA to SU-8 bonding for polymer based lab-on-a-chip systems with integrated optics

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Nielsen, Theodor; Clausen, Bjarne Hans


    We present an adhesive bonding technique developed for SU-8 based "lab-on-a-chip"- systems with integrated optical components. Microfluidic channels and optical components (e.g. wave-guides) are defined in SU-8 photoresist on a Pyrex glass substrate. The microfluidic channels are sealed by a second...

  15. Microfabrication of PDMS microchannels using SU-8/PMMA moldings and their sealing to polystyrene substrates (United States)

    Bubendorfer, Andrea; Liu, Xianming; Ellis, Amanda V.


    In this paper we show increased interfacial bonding of a photoresist (SU-8) deposited onto highly polished poly(methyl methacrylate) (PMMA) substrates containing a UV absorber. We also demonstrate the facile sealing/covalent bonding of 100 µm × 20 µm PDMS replica microchannels, made from these PMMA/SU-8 moldings, onto thermally polymerized styrene. Sealing was achieved through radio-frequency plasma discharge (RFPD) oxygen plasma treatment.

  16. Arrayed SU-8 polymer thermal actuators with inherent real-time feedback for actively modifying MEMS’ substrate warpage (United States)

    Wang, Xinghua; Xiao, Dingbang; Chen, Zhihua; Wu, Xuezhong


    This paper describes the design, fabrication and characterization of a batch-fabricated micro-thermal actuators array with inherent real-time self-feedback, which can be used to actively modify micro-electro-mechanical systems’ (MEMS’) substrate warpage. Arrayed polymer thermal actuators utilize SU-8 polymer (a thick negative photoresist) as a functional material with integrated Ti/Al film-heaters as a microscale heat source. The electro-thermo-mechanical response of a micro-fabricated actuator was measured. The resistance of the Al/Ti film resistor varies obviously with ambient temperature, which can be used as inherent feedback for observing real-time displacement of activated SU-8 bumps (0.43 μm Ω-1). Due to the high thermal expansion coefficient, SU-8 bumps tend to have relatively large deflection at low driving voltage and are very easily integrated with MEMS devices. Experimental results indicated that the proposed SU-8 polymer thermal actuators (array) are able to achieve accurate rectification of MEMS’ substrate warpage, which might find potential applications for solving stress-induced problems in MEMS.

  17. Chemical synthesis on SU-8

    DEFF Research Database (Denmark)

    Qvortrup, Katrine; Taveras, Kennedy; Thastrup, Ole


    In this paper we describe a highly effective surface modification of SU-8 microparticles, the attachment of appropriate linkers for solid-supported synthesis, and the successful chemical modification of these particles via controlled multi-step organic synthesis leading to molecules attached...

  18. Moisture resistance of SU-8 and KMPR as structural material for integrated gaseous detectors

    NARCIS (Netherlands)

    Blanco Carballo, V.M.; Melai, J.; Salm, Cora; Schmitz, Jurriaan


    This paper treats the moisture resistance of SU-8 and KMPR, two photoresists considered as structural material in microsystems. Our experiments focus on the moisture resistance of newly developed radiation imaging detectors containing these resists. Since these microsystems will be used unpackaged,

  19. Cloning SU8 silicon masters using epoxy resins to increase feature replicability and production for cell culture devices (United States)

    Kamande, J. W.; Wang, Y.; Taylor, A. M.


    In recent years, there has been a dramatic increase in the use of poly(dimethylsiloxane) (PDMS) devices for cell-based studies. Commonly, the negative tone photoresist, SU8, is used to pattern features onto silicon wafers to create masters (SU8-Si) for PDMS replica molding. However, the complexity in the fabrication process, low feature reproducibility (master-to-master variability), silane toxicity, and short life span of these masters have been deterrents for using SU8-Si masters for the production of cell culture based PDMS microfluidic devices. While other techniques have demonstrated the ability to generate multiple devices from a single master, they often do not match the high feature resolution (∼0.1 μm) and low surface roughness that soft lithography masters offer. In this work, we developed a method to fabricate epoxy-based masters that allows for the replication of features with high fidelity directly from SU8-Si masters via their PDMS replicas. By this method, we show that we could obtain many epoxy based masters with equivalent features to a single SU8-Si master with a low feature variance of 1.54%. Favorable feature transfer resolutions were also obtained by using an appropriate Tg epoxy based system to ensure minimal shrinkage of features ranging in size from ∼100 μm to epoxy masters with Cr/Au lead to effective demolding and yield PDMS chambers that are suitable for long-term culturing of sensitive primary hippocampal neurons. Finally, we incorporated pillars within the Au-epoxy masters to eliminate the process of punching media reservoirs and thereby reducing substantial artefacts and wastage. PMID:26180572

  20. Cloning SU8 silicon masters using epoxy resins to increase feature replicability and production for cell culture devices. (United States)

    Kamande, J W; Wang, Y; Taylor, A M


    In recent years, there has been a dramatic increase in the use of poly(dimethylsiloxane) (PDMS) devices for cell-based studies. Commonly, the negative tone photoresist, SU8, is used to pattern features onto silicon wafers to create masters (SU8-Si) for PDMS replica molding. However, the complexity in the fabrication process, low feature reproducibility (master-to-master variability), silane toxicity, and short life span of these masters have been deterrents for using SU8-Si masters for the production of cell culture based PDMS microfluidic devices. While other techniques have demonstrated the ability to generate multiple devices from a single master, they often do not match the high feature resolution (∼0.1 μm) and low surface roughness that soft lithography masters offer. In this work, we developed a method to fabricate epoxy-based masters that allows for the replication of features with high fidelity directly from SU8-Si masters via their PDMS replicas. By this method, we show that we could obtain many epoxy based masters with equivalent features to a single SU8-Si master with a low feature variance of 1.54%. Favorable feature transfer resolutions were also obtained by using an appropriate Tg epoxy based system to ensure minimal shrinkage of features ranging in size from ∼100 μm to epoxy masters with Cr/Au lead to effective demolding and yield PDMS chambers that are suitable for long-term culturing of sensitive primary hippocampal neurons. Finally, we incorporated pillars within the Au-epoxy masters to eliminate the process of punching media reservoirs and thereby reducing substantial artefacts and wastage.

  1. SU-8 Guiding Layer for Love Wave Devices

    Directory of Open Access Journals (Sweden)

    Michael I. Newton


    Full Text Available SU-8 is a technologically important photoresist used extensively for thefabrication of microfluidics and MEMS, allowing high aspect ratio structures to beproduced. In this work we report the use of SU-8 as a Love wave sensor guiding layerwhich allows the possibility of integrating a guiding layer with flow cell during fabrication.Devices were fabricated on ST-cut quartz substrates with a single-single finger design suchthat a surface skimming bulk wave (SSBW at 97.4 MHz was excited. SU-8 polymer layerswere successively built up by spin coating and spectra recorded at each stage; showing afrequency decrease with increasing guiding layer thickness. The insertion loss andfrequency dependence as a function of guiding layer thickness was investigated over thefirst Love wave mode. Mass loading sensitivity of the resultant Love wave devices wasinvestigated by deposition of multiple gold layers. Liquid sensing using these devices wasalso demonstrated; water-glycerol mixtures were used to demonstrate sensing of density-viscosity and the physical adsorption and removal of protein was also assessed usingalbumin and fibrinogen as model proteins.

  2. In situ SU-8 silver nanocomposites

    DEFF Research Database (Denmark)

    Fischer, Søren Vang; Uthuppu, Basil; Jakobsen, Mogens Havsteen


    Nanocomposite materials containing metal nanoparticles are of considerable interest in photonics and optoelectronics applications. However, device fabrication of such materials always encounters the challenge of incorporation of preformed nanoparticles into photoresist materials. As a solution to...

  3. Further outgassing studies on SU-8

    NARCIS (Netherlands)

    Melai, J.; Blanco Carballo, V.M.; Salm, Cora; Wolters, Robertus A.M.; Schmitz, Jurriaan


    SU-8 is often used as a structural material in microsystems. In this work the outgassing characteristics from such cross-linked SU-8 layers are studied using Mass Spectrometry and Gas Chromatography techniques. With these methods the composition of the released matter can be identified, also the

  4. SU-8 Based Piezoresistive Mechanical Sensor

    DEFF Research Database (Denmark)

    Thaysen, Jacob; Yalcinkaya, Arda Deniz; Vestergaard, R.K.


    We present the first SU-8 based piezoresistive mechanical sensor. Conventionally, silicon has been used as a piezoresistive material due to its high gauge factor and thereby high sensitivity to strain changes in a sensor. By using the fact that SU-8 is much softer than silicon and that a gold...

  5. A high aspect ratio SU-8 fabrication technique for hollow microneedles for transdermal drug delivery and blood extraction (United States)

    Chaudhri, Buddhadev Paul; Ceyssens, Frederik; De Moor, Piet; Van Hoof, Chris; Puers, Robert


    Protein drugs, e.g. hormonal drugs, cannot be delivered orally to a patient as they get digested in the gastro-intestinal (GI) tract. Thus, it is imperative that these kinds of drugs are delivered transdermally through the skin. To provide for real-time feedback as well as to test independently for various substances in the blood, we also need a blood sampling system. Microneedles can perform both these functions. Further, microneedles made of silicon or metal have the risk of breaking inside the skin thereby leading to complications. SU-8, being approved of as being biocompatible by the Food and Drug Agency (FDA) of the United States, is an attractive alternative because firstly it is a polymer material, thereby reducing the chances of breakages inside the skin, and secondly it is a negative photoresist, thereby leading to ease of fabrication. Thus, here we present very tall (around 1600 µm) SU-8 polymer-based hollow microneedles fabricated by a simple and repeatable process, which are a very good candidate for transdermal drug delivery as well as blood extraction. The paper elaborates on the details that allow the fabrication of such extreme aspect ratios (>100).

  6. High resolution 100 kV electron beam lithography in SU-8

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Jakobsen, S.; Schmidt, M.S.


    High resolution 100 kV electron beam lithography in thin layers of the negative resist SU-8 is demonstrated. Sub-30 nm lines with a pitch down to 300 nm are written in 100 nm thick SU-8. Two reactive ion etch processes are developed in order to transfer the SU-8 structures into a silicon substrate......, a Soft O-2-Plasma process to remove SU-8 residues on the silicon surface after development and a highly anisotropic SF6/O-2/CHF3 based process to transfer the pattern into a silicon substrate, with selectivity between silicon and SU-8 of approximately 2. 30 nm lines patterned in SU-8 are successfully...

  7. SU-8 passivation of type-II InAs/GaSb strained layer superlattice detectors (United States)

    Kim, H. S.; Plis, E.; Gautam, N.; Khoshakhlagh, A.; Myers, S.; Kutty, M. N.; Sharma, Y.; Dawson, L. R.; Krishna, S.


    We report on surface passivation studies for type-II InAs/GaSb superlattice (SL) PIN detectors designed to operate in the mid-wave infrared (MWIR) region and the long wavelength infrared (LWIR) spectrum. The two SL structures were grown by molecular beam epitaxy and processed into mesa diodes using standard lithography. A simple spin on photoresist, SU-8, was used to passivate the sample after a wet etch. Optical and electrical measurements were then undertaken on the two devices. The dark current density of a single pixel device with SU-8 passivation is reduced by four orders of magnitude and by a factor of eight compared to devices without any passivation for the MWIR and LWIR pin detectors, respectively, at 77K.

  8. SU-8 Cantilever Sensor with Integrated Read-Out

    DEFF Research Database (Denmark)

    Johansson, Alicia Charlotte


    kan måles med optiske målesystemer eller ved hjælp af integrerede piezoresistorer. Dette PhD projekt beskriver design, fremstilling og indpakning af en polymer cantilever chip med piezoresistive udlæsning. Chippen er fremstillet i den epoxy-baserede negative fotoresist SU-8, på nær de integrerede guld...... resistorer. Cantilever baserede sensorer bliver normalt fremstillet i silicium men fordelen ved at bruge SU-8 er, at SU-8 er et blødere materiale som er billigere og hurtigere at fremstille. For at opnå elektrisk kontakt fra chippen til et printet kredsløbskort, er flere metoder så som flip-chip bonding...... blevet undersøgt. Chippen er blevet brugt til overfladestress målinger i væske, så som thiol binding og detektion af pH forandringer. Teoretiske beregninger af følsomheden for overfladestress og den mindste målbare overfladestress bliver også beskrevet. Til sidst diskuteres muligheden for at binde...

  9. Conformal coating by photoresist of sharp corners of anisotropically etched through-holes in silicon

    DEFF Research Database (Denmark)

    Heschel, Matthias; Bouwstra, Siebe


    The authors describe a photoresist treatment yielding conformal coating of three-dimensional silicon structures. This even includes the sharp corners of through-holes obtained by anisotropic etching in (100)-silicon. Resist reflow from these corners is avoided by replacing the common baking proce...... procedure with a proper vacuum treatment. The investigated photoresist is Shipley's Eagle 2100 ED, a negative-working electrodeposited photoresist. Electrical frontside to backside interconnections have been made using this photoresist as an etch mask...

  10. Invisible Security Printing on Photoresist Polymer Readable by Terahertz Spectroscopy

    Directory of Open Access Journals (Sweden)

    Hee Jun Shin


    Full Text Available We experimentally modulate the refractive index and the absorption coefficient of an SU-8 dry film in the terahertz region by UV light (362 nm exposure with time dependency. Consequently, the refractive index of SU-8 film is increased by approximately 6% after UV light exposure. Moreover, the absorption coefficient also changes significantly. Using the reflective terahertz imaging technique, in addition, we can read security information printed by UV treatment on an SU-8 film that is transparent in the visible spectrum. From these results, we successfully demonstrate security printing and reading by using photoresist materials and the terahertz technique. This investigation would provide a new insight into anti-counterfeiting applications in fields that need security.

  11. Photoresists for Microlithography

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 8. Photoresists for Microlithography - The Role of Polymer Microstructure. Debmalya Roy P K Basu S V Eswaran. General Article Volume 7 Issue 8 August 2002 pp 59-66 ...

  12. Towards a compact SU-8 micro-direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Esquivel, J.P.; Santander, J.; Cane, C.; Sabate, N. [Instituto de Microelectronica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193 Bellaterra, Barcelona (Spain); Senn, T.; Loergen, M.; Loechel, B. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Application Centre for Microengineering, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Hernandez-Fernandez, P. [Dpto. Quimica-Fisica Aplicada, Facultad de Ciencias, Universidad Autonoma de Madrid (UAM), C/Francisco Tomas y Valiente 7, 28049 Madrid (Spain); Rojas, S. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, 28049 Madrid (Spain)


    This paper presents an all-polymer micro-direct methanol fuel cell (microDMFC) fabricated with SU-8 photoresist. The present development exploits the capability of SU-8 components to bond to each other by a hot-pressing process and obtain a compact device. The device is formed by a membrane electrode assembly (MEA) sandwiched between two current collectors. The MEA consists of a porous SU-8 membrane filled with a proton exchange polymer and covered by a thin layer of carbon-based electrodes with a low catalyst loading (1.0 mg cm{sup -2}). The current collectors consist of two metalized SU-8 plates provided with a grid of through-holes that allow delivering the reactants to the MEA by diffusion. Fuel cell characterization was performed by measuring the polarization curves under different methanol concentrations and temperatures. The components were first tested using an external casing. A maximum power density of 4.15 mW cm{sup -2} was measured with this assembly working with a 4 M methanol concentration and at a temperature of 40 C. The components were then bonded to obtain a compact micro-direct methanol fuel cell that yielded a power density of 0.65 mW cm{sup -2} under the same conditions. Despite this decrease in power density after bonding, the drastic reduction of the device dimensions resulted in an increase of more than 50 times the previous volumetric power density. The results obtained validate this novel approach to an all-polymer micro-fuel cell. (author)

  13. New Formation Technology of Plasma Display Panel Barrier-Rib Structure Using Silicone Rubber Mold Transferred from SU-8 Master Structure (United States)

    Son, Seung-Hyun; Park, Yong-Suk; Choi, Sie-Young


    A new formation technology for a plasma display panel (PDP) barrier-rib structure is presented to realize a barrier rib with a high aspect ratio and reduce the manufacturing cost. In this study, we used an SU-8 50 photoresist, which is sensitive to UV irradiation, instead of polymethylmethacrylate (PMMA) which is sensitive to X-ray irradiation, so that the silicone rubber mold could be applicable to a large-area PDP. The first step is to produce an SU-8 master structure using amorphous silicon as an adhesion layer between a glass substrate and SU-8 photoresist. Second, a precise soft mold is manufactured for mass replication of the PDP barrier-rib construction, by molding liquid silicone rubber onto the glass substrate with lithographically defined SU-8 master structures. Third, a PDP barrier-rib structure is formed using the pattern-transferring process with a reusable silicone rubber mold. This is a very simple and inexpensive process consisting with printing of barrier-rib paste, drying, pattern-transferring, and sintering. The pattern-transferring process with a soft mold also demonstrates that the disadvantages of the conventional mold pressing process with a hard mold can be overcome. Consequently, by using the pattern-transferring process with the silicone rubber mold transferred from the SU-8 master structure, the desired barrier-rib shapes can be realized with a high aspect ratio and various dimensions.

  14. Functionalized SU-8 patterned with X-ray Lithography

    DEFF Research Database (Denmark)

    Balslev, Søren; Romanato, F.


    spontaneous emission light source that couples out light normal to the chip plane. In addition we examine the influence of the x-ray irradiation on the fluorescence of thin films of dye doped SU-8. The dye embedded in the SU-8 is optically excited during, characterization by an external light source tuned...

  15. Vacuum induced photoresist outgassing (United States)

    Waterman, Justin; Mbanaso, Chimaobi; Denbeaux, Gregory


    In order to continue the trend toward smaller feature sizes in lithography, new methods of lithography will be needed. A likely method for printing features 32 nm and smaller is extreme ultraviolet (EUV) lithography. EUV allows for features to be printed that are smaller than the current methods can achieve. However, outgassing of the photoresist is a concern for EUV lithography. The outgassed components can lead to contamination of the optics, degrading the reflectivity and hence lowering throughput of the exposure tools. Outgassing due to EUV exposure has been investigated by many groups. However, there were no complete investigations available of vacuum induced outgassing. In this paper, several methods were employed to investigate the outgassing due to vacuum. It was found that the vacuum induced outgassing outgassed a similar number of molecules as the outgassing due to EUV exposure. Furthermore, almost all of the outgassing was completed after about two minutes in vacuum. To mitigate the potential concern of outgassing due to vacuum causing contamination of optics, this work shows that photoresist coated silicon wafers only require about two minutes of pumping prior to insertion near the optics within EUV lithography tools.

  16. SU-8 as a Material for Microfabricated Particle Physics Detectors

    CERN Document Server

    Maoddi, Pietro; Jiguet, Sebastien; Renaud, Philippe


    Several recent detector te chnologies developed for particle physics applications are based on microfabricated structures. Dete ctors built with this approach generally exhibit the overall best performance in te rms of spatial and time resolution. Many properties of the SU-8 photoepoxy make it suitable for the manufacturing of microstructured particle detectors. This arti cle aims to review some emerging detector technologies making use of SU-8 microstructu ring, namely micropatte rn gaseous detectors and microfluidic scintillation detectors. Th e general working principle and main process steps for the fabrication of each device are reported, with a focus on the advantages brought to the device functionality by the us e of SU-8. A novel process based on multiple bonding steps for the fabrication of thin multila yer microfluidic scin tillation detectors developed by the authors is presented. Finally, a brief overview of the applications for the discussed devices is given.

  17. Development of untethered SU-8 polymer scratch drive microrobots

    KAUST Repository

    Valencia Garcia, Manuel


    This paper presents the design, simulation, fabrication and testing of novel, untethered SU-8 polymer microrobots based on scratch drive actuators (SDAs). The design consists of two 100×120×10μm linked SDAs, individually operated close to their resonant frequencies. The resonant frequency and deflection behavior of an individual SDA can be controlled by its shape, thickness, and stiffening design features. As a result, paired SDAs can be actuated individually or simultaneously by a multifrequency driving signal, allowing for two-dimensional displacement. The fabrication process uses SU-8 as structural material and PMGI as sacrificial material. The SU-8 provides a flexible material for the SDA\\'s plates as well as the bushing. Finally, a Cr/Au layer is blanket deposited to provide electrical conductivity.

  18. SU-8 Photolithography as a Toolbox for Carbon MEMS

    Directory of Open Access Journals (Sweden)

    Rodrigo Martinez-Duarte


    Full Text Available The use of SU-8 as precursor for glass-like carbon, or glassy carbon, is presented here. SU-8 carbonizes when subject to high temperature under inert atmosphere. Although epoxy-based precursors can be patterned in a variety of ways, photolithography is chosen due to its resolution and reproducibility. Here, a number of improvements to traditional photolithography are introduced to increase the versatility of the process. The shrinkage of SU-8 during carbonization is then detailed as one of the guidelines necessary to design carbon patterns. A couple of applications—(1 carbon-electrode dielectrophoresis for bioparticle manipulation; and (2 the use of carbon structures as micro-molds are also presented.

  19. Droplet backside exposure for making slanted SU-8 microneedles. (United States)

    Kwon, Ki Yong; Bi, Xiaopeng; Li, Wen


    This paper presented a droplet backside exposure (DBE) method for making slanted microneedle structures on a flexible polymer substrate. To demonstrate the feasibility of the DBE approach, SU-8 microneedle arrays were fabricated on polydimethylsiloxane (PDMS) substrates. The length of the microneedles was controlled by tuning the volume of the SU-8 droplet, utilizing the wetting barrier phenomenon at a liquid-vapor-hydrophilic surface-hydrophobic surface interface. The experimental results showed excellent repeatability and controllability of the DBE method for microneedle fabrication. Analytical models were also studied to predict the dimensions of the microneedles, which agreed with the experimental data.

  20. A High-Throughput SU-8Microfluidic Magnetic Bead Separator

    DEFF Research Database (Denmark)

    Bu, Minqiang; Christensen, T. B.; Smistrup, Kristian


    We present a novel microfluidic magnetic bead separator based on SU-8 fabrication technique for high through-put applications. The experimental results show that magnetic beads can be captured at an efficiency of 91 % and 54 % at flow rates of 1 mL/min and 4 mL/min, respectively. Integration of s...

  1. Multiplex polymerase chain reaction (PCR) on a SU-8 chip

    DEFF Research Database (Denmark)

    Christensen, Troels Balmer; Bang, Dang Duong; Wolff, Anders


    We present the detection of Campylobacter at species level using multiplex PCR in a micro fabricated PCR chip. The chip is based on the polymer SU-8 that allows integration with different microfluidic components, e.g., sample pre-treatment before PCR, and DNA detection simultaneously with or afte...

  2. SU-8-based microneedles for in vitro neural applications (United States)

    Altuna, Ane; Gabriel, Gemma; Menéndez de la Prida, Liset; Tijero, María; Guimerá, Anton; Berganzo, Javier; Salido, Rafa; Villa, Rosa; Fernández, Luis J.


    This paper presents novel design, fabrication, packaging and the first in vitro neural activity recordings of SU-8-based microneedles. The polymer SU-8 was chosen because it provides excellent features for the fabrication of flexible and thin probes. A microprobe was designed in order to allow a clean insertion and to minimize the damage caused to neural tissue during in vitro applications. In addition, a tetrode is patterned at the tip of the needle to obtain fine-scale measurements of small neuronal populations within a radius of 100 µm. Impedance characterization of the electrodes has been carried out to demonstrate their viability for neural recording. Finally, probes are inserted into 400 µm thick hippocampal slices, and simultaneous action potentials with peak-to-peak amplitudes of 200-250 µV are detected.

  3. Improved anti-stiction coating of SU-8 molds

    DEFF Research Database (Denmark)

    Lange, Jacob Moresco; Clausen, Casper Hyttel; Svendsen, Winnie Edith


    We have developed a simple method for the improved release of embossed poly(methyl methacrylate) (PMMA) as well as casted poly(dimethyl siloxane) (PDMS) from a SU-8 mold using vapor phase deposition of 1H,1H,2H,2H-Perfluorodecyltrichlorosilane (FDTS). We have further investigated if prior breakage...... the method for the mold fabrication as well as the vapor phase deposition of FDTS onto the mold is described; examples of released final devices using this method in PMMA and PDMS are presented. (C) 2010 Elsevier B.V. All rights reserved....

  4. SU-8 etching in inductively coupled oxygen plasma

    DEFF Research Database (Denmark)

    Rasmussen, Kristian Hagsted; Keller, Stephan Sylvest; Jensen, Flemming


    Structuring or removal of the epoxy based, photo sensitive polymer SU-8 by inductively coupled plasma reactive ion etching (ICP-RIE) was investigated as a function of plasma chemistry, bias power, temperature, and pressure. In a pure oxygen plasma, surface accumulation of antimony from the photo......-initiator introduced severe roughness and reduced etch rate significantly. Addition of SF6 to the plasma chemistry reduced the antimony surface concentration with lower roughness and higher etch rate as an outcome. Furthermore the etch anisotropy could be tuned by controlling the bias power. Etch rates up to 800 nm...

  5. Fabrication of high-aspect ratio SU-8 micropillar arrays

    DEFF Research Database (Denmark)

    Amato, Letizia; Keller, Stephan S.; Heiskanen, Arto


    to the resolution limit of photolithography. This paper describes process optimization for the fabrication of dense SU-8 micropillar arrays (2.5μm spacing) with nominal height ⩾20μm and nominal diameter ⩽2.5μm (AR ⩾8). Two approaches, differing in temperature, ramping rate and duration of the baking steps were...... compared as part of the photolithographic processing, in order to evaluate the effect of baking on the pattern resolution. Additionally, during the post-processing, supercritical point drying and hard baking were introduced yielding pillars with diameter 1.8μm, AR=11 and an improved temporal stability....

  6. Combined electron beam and UV lithography in SU-8

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Thamdrup, Lasse Højlund; Mironov, Andrej


    We present combined electron beam and UV lithography (CEUL) in SU-8 as a fast and flexible lithographic technique for prototyping of functional polymer devices and pattern transfer applications. CEUL is a lithographic technique suitable for defining both micrometer and nanometer scale features...... in a single polymer film on the wafer scale. The height of the micrometer and nanometer scale features is matched within 30 nm. As a pattern transfer application, we demonstrate stamp fabrication and thermal nanoimprint of a 2-dimensional array of 100 nm wide lines with a pitch of 380 nm in connection...

  7. Static and dynamic photoresist shrinkage effects in EUV photoresists (United States)

    Bunday, Benjamin; Montgomery, Cecilia; Montgomery, Warren; Cordes, Aaron


    Photoresist shrinkage (a.k.a. line slimming) is an important systematic uncertainty source in critical dimension-scanning electron microscope (CD-SEM) metrology of lithographic features [1][2][3][4][5]. In terms of metrology gauge metrics, it influences both the precision and the accuracy of CD-SEM measurements, while locally damaging the sample. Minimization or elimination of shrinkage is desirable, yet elusive. This error source will furthermore be a factor in CDSEM metrology on such polymer materials into the era of EUV lithography, such that learning to work around this issue will continue to be necessary. Recent work has demonstrated improved understanding of the trends in the shrinkage response depending on electron beam and target parameters in the static measurement case [2][3][4][5][6]. Another recent work has highlighted a second mode of shrinkage that is apparent over time and progresses as a function of time between consecutive measurements, a form of "dynamic shrinkage" that appears to be activated by electron beam, in which the activated feature perpetually and logarithmically shrinks [7][8]. In this work, we will explore both the static and dynamic shrinkage behaviors of various EUV photoresists. The static shrinkage behaviors will be tested for compliance with the SEMATECH shrinkage model [5][6], and further studies will confirm whether or not the dynamic effects are observable. Knowledge of secondary trends in dynamic shrinkage will also be further explored, including how these vary with electron beam energy, activation dose, feature size, and other parameters.

  8. Fabrication of SU-8 low frequency electrostatic energy harvester

    KAUST Repository

    Ramadan, Khaled S.


    A 1500μm × 1500μm × 150μm out-of-plane, gap closing, electrostatic energy harvester is designed and fabricated to harvest low-frequency ambient vibrations. SU-8 is used to fabricate the proof mass (1200μm × 1200μm × 150μm) and the 5 m springs. Different harvesters were designed to harvest at 50, 75 and 110 Hz. At 110 Hz, Simulations show that with an input vibration of 10 μm amplitude at the frequency of resonance of the structure, the energy harvester should generate an average output power density of 0.032μW/mm3. This is the most area-efficient low-frequency electrostatic harvester to-date. © 2011 IEEE.

  9. Gold Nanoparticles-Coated SU-8 for Sensitive Fluorescence-Based Detections of DNA

    DEFF Research Database (Denmark)

    Cao, Cuong; Birtwell, Sam W.; Høgberg, Jonas


    that use fluorescence as the predominant detection workhorse. Here, we show that deposition of a thin gold nanoparticles layer onto the SU-8 surface significantly reduces the autofluorescence of the coated SU-8 surface by as much as 81% compared to bare SU-8. Furthermore, DNA probes can easily...

  10. SU(8) family unification with boson-fermion balance

    CERN Multimedia

    CERN. Geneva


    Grand unification has been intensively investigated for over forty years, and many different approaches have been tried. In this talk I propose a model that involves three ingredients that do not appear in the usual constructions: (1) boson--fermion balance without full supersymmetry, (2) canceling the spin 1/2 fermion gauge anomalies against the anomaly from a gauged spin 3/2 gravitino, and (3) using a scalar field representation with non-zero U(1) generator to break the SU(8) gauge symmetry through a ground state which, before dynamical symmetry breaking, has a periodic U(1) generator structure. The model has a number of promising features: (1) natural incorporation of three families, (2) incorporation of the experimentally viable flipped SU(5) model, (3) a symmetry breaking pathway to the standard model using the scalar field required by boson-fermion balance, together with a stage of most attractive channel dynamical symmetry breaking, without postulating additional Higgs fields, (4) vanishing of bare Yuk...

  11. Fabrication of micropressure sensor using SU-8/silver as piezoresistor and overhead projector transparency as substrate (United States)

    Wong, Wah Seng; Azid, Ishak Abdul; Ibrahim, Kamarulazizi; Devarajan, Mutharasu


    This paper proposes a low-cost SU-8 pressure sensor fabricated using a piezoresistive material, SU-8/silver composite (SU-8/Ag), and a substrate material, overhead projector (OHP) transparency. SU-8/Ag has higher gauge factor (26.3) but shows a lower stiffness (2 GPa) compared with doped silicon. The OHP transparency substrate is cheap, easily forms the desired shape, is transparent to light (allows backside exposure), and allows for the dry release method through OHP transparency. Fabrication and characterization in this study were carried out using a typical semiconductor lab setup. The fabricated sensor showed high sensitivity (21.5 μV/Pa), low linearity error (Pearson's correlation coefficient=0.994937), and no apparent hysteresis response. The fabricated sensor with SU-8/Ag as the piezoresistive material exhibited 41 times higher sensitivity compared to that found in a previous study based on SU-8 and doped polysilicon.

  12. Deep proton writing of high aspect ratio SU-8 micro-pillars on glass

    Energy Technology Data Exchange (ETDEWEB)

    Ebraert, Evert, E-mail:; Rwamucyo, Ben; Thienpont, Hugo; Van Erps, Jürgen


    Deep proton writing (DPW) is a fabrication technology developed for the rapid prototyping of polymer micro-structures. We use SU-8, a negative resist, spincoated in a layer up to 720 μm-thick in a single step on borosilicate glass, for irradiation with a collimated 12 MeV energy proton beam. Micro-pillars with a slightly conical profile are irradiated in the SU-8 layer. We determine the optimal proton fluence to be 1.02 × 10{sup 4} μm{sup −2}, with which we are able to repeatably achieve micro-pillars with a top-diameter of 138 ± 1 μm and a bottom-diameter of 151 ± 3 μm. The smallest fabricated pillars have a top-diameter of 57 ± 5 μm. We achieved a root-mean-square sidewall surface roughness between 19 nm and 35 nm for the fabricated micro-pillars, measured over an area of 5 × 63.7 μm. We briefly discuss initial testing of two potential applications of the fabricated micro-pillars. Using ∼100 μm-diameter pillars as waveguides for gigascale integration optical interconnect applications, has shown a 4.7 dB improvement in optical multimode fiber-to-fiber coupling as compared to the case where an air–gap is present between the fibers at the telecom wavelength of 1550 nm. The ∼140 μm-diameter pillars were used for mold fabrication with silicone casting. The resulting mold can be used for hydrogel casting, to obtain hydrogel replicas mimicking human tissue for in vitro bio-chemical applications.

  13. Single-mode waveguides with SU-8 polymer core and cladding for MOEMS applications

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Boisen, Anja


    Fabrication and optical characterization of singlemode polymeric embedded waveguides are performed. A specific material combination (SU-8 2005 as core and the modified SU-8 mr-L 6050XP as cladding) is chosen in order to obtain a small refractive index difference for single-mode propagation combin...

  14. Considerations on using SU-8 as a construction material for high aspect ratio structures

    NARCIS (Netherlands)

    Melai, J.; Salm, Cora; Smits, Sander M.; Blanco Carballo, V.M.; Schmitz, Jurriaan; Hageluken, Ben


    This paper discusses two material aspects of SU-8 that have up till now been insufficiently documented. We present initial results on the outgassing behavior and a study on the dielectric properties of SU-8 at high bias voltage. The dielectric strength is determined to be at least 2 MV/cm. These

  15. Resolution, LER, and sensitivity limitations of photoresists (United States)

    Gallatin, Gregg M.; Naulleau, Patrick; Niakoula, Dimitra; Brainard, Robert; Hassanein, Elsayed; Matyi, Richard; Thackeray, Jim; Spear, Kathleen; Dean, Kim


    Recent experimental results and modeling both indicate that whereas it is possible to optimize a photoresist and process to achieve separately a desired resolution or line edge roughness or sensitivity, it will be difficult if not impossible to achieve all three simultaneously using current standard chemically amplified photoresists and processes. This tradeoff among Resolution, Line Edge Roughness (LER) and Sensitivity is termed the RLS tradeoff. Here we review the progress to date of a SEMATECH-funded program to develop an experimentally verified model of the relationship among resolution, LER and sensitivity and use it to determine approaches for "breaking" the RLS tradeoff.

  16. A modified photoresist resistant to oxygen plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ashburn, S.P.; DuBois, T.D.; Frieser, R.G.; Tranjan, F.M.; Bobbio, S.M. (Dept. of Chemistry, Univ. of North Carolina at Charlotte, Charlotte, NC (US)); Jones, S.K. (Microelectronics Center of North Carolina, Research Triangle Park, NC (US))


    Conventional photoresists have been modified by the incorporation of a phosphorus-containing compound, {ital i.e.}, phosphonitrilic chloride trimer (P{sub 3}N{sub 3}Cl{sub 6}). The modification was achieved by simply dissolving P{sub 3}N{sub 3}Cl{sub 6} (PNCT) in conventional photoresists. The phosphorus concentration varied from 5 weight percent (w/o) to 12 w/o in the modified photoresist films. These films formed a barrier layer when exposed to oxygen plasmas. After the layer was formed, no measurable resist etch rate could be detected. The resolution and mechanical properties of the modified resist films were essentially unchanged, although an increase by a factor of 1.5 in the exposure threshold was observed. Features of less than 1 {mu}m lines and spaces were anisotropically etched in polyamide masked by this photoresist. Furthermore, metal lift-off structures have been obtained using a bilayer process employing the modified resist.

  17. Investigation on the mechanism of nitrogen plasma modified PDMS bonding with SU-8

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chengxin; Yuan, Yong J., E-mail:


    Graphical abstract: - Highlights: • Different nitrogen plasma processes modified PDMS bonding with SU-8 had been studied. • The effect of nitrogen plasma modification would produce the best result and the recovery of PDMS hydrophobicity could be delayed. - Abstract: Polydimethylsiloxane (PDMS) and SU-8 are both widely used for microfluidic system. However, it is difficult to permanently seal SU-8 microfluidic channels using PDMS with conventional methods. Previous efforts of combining these two materials mainly employed oxygen plasma modified PDMS. The nitrogen plasma modification of PDMS bonding with SU-8 is rarely studied in recent years. In this work, the mechanism of nitrogen plasma modified PDMS bonding with SU-8 was investigated. The fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle of a water droplet were used to analyze the nitrogen plasma modified surface and the hydrophilic stability of PDMS samples. Pull-off tests were used for estimating the bonding effect of interface between nitrogen plasma modified PDMS and SU-8.

  18. Epoxy based photoresist/carbon nanoparticle composites

    DEFF Research Database (Denmark)

    Lillemose, Michael; Gammelgaard, Lauge; Richter, Jacob


    We have fabricated composites of SU-8 polymer and three different types of carbon nanoparticles (NPs) using ultrasonic mixing. Structures of composite thin films have been patterned on a characterization chip with standard UV photolithography. Using a four-point bending probe, a well defined stress...... is applied to the composite thin film and we have demonstrated that the composites are piezoresistive. Stable gauge factors of 5-9 have been measured, but we have also observed piezoresistive responses with gauge factors as high as 50. As SU-8 is much softer than silicon and the gauge factor of the composite...

  19. Precise measurement of photoresist cross-sectional shape change caused by SEM-induced shrinkage (United States)

    Ohashi, Takeyoshi; Sekiguchi, Tomoko; Yamaguchi, Atsuko; Tanaka, Junichi; Kawada, Hiroki


    The mechanism of photoresist shrinkage induced by electron-beam (EB) irradiation was studied. A precise cross-sectional profile of a photoresist pattern was obtained by a scanning transmission electron microscope (STEM) after atomic layer deposition of HfO2 on the sample patterns. Photoresist lines and spaces fabricated with positive-tone development and negative-tone development were exposed to an EB with much higher dose than a practical dose (to accelerate shrinkage intentionally). The obtained STEM images of the patterns before and after EB irradiation show that the shrinkage of the negative-tone-developed patterns is smaller than that of the positive-tone-developed patterns. This observation is explained by the fact that negative-tone-developed photoresist molecules do not contain protection groups, whose volatilization caused by EB irradiation is one of the origins of shrinkage. Another finding is that the EB irradiation causes top-rounding and necking of the pattern profile as well as linewidth slimming. The rounding of the pattern top profile suggests that the pattern's shape was elastically deformed. In addition, EB irradiation only onto the spaces caused sidewall shrinkage and a necking profile, although no electrons were irradiated directly onto the pattern. These phenomena are considered to be due to the electrons scattered from the spaces to the pattern sidewall. Finally, a Monte Carlo simulation of electron scattering showed that the distribution of the deposited EB energy on the pattern surface corresponds to the above-described change in pattern shape. Consequently, these observations and simulation results clarify the importance of the effect of elastic shape change and the impact of the electrons scattered from the underlying layer onto the sidewall in the mechanism of photoresist shrinkage.

  20. Polydimethylglutarimide (PMGI) as a sacrificial material for SU-8 surface-micromachining (United States)

    Foulds, I. G.; Johnstone, R. W.; Parameswaran, M.


    SU-8 is finding increased use as a structural polymer MEMS material due to its biocompatibility, mechanical properties and low cost. The goal of this work is to expand the use of SU-8 through the creation of SU-8-based surface-micromachining processes that use polydimethylglutarimide (PMGI) as a sacrificial layer. PMGI is a deep-UV positive resist, used mainly for bilayer lift-off processes. PMGI is a good sacrificial layer candidate, as it is spinable at a wide variety of thicknesses, is photopatternable and has a glass transition temperature greater than the processing temperatures required for SU-8. PMGI is shown to be useful as a sacrificial layer for SU-8 surface micromachining processes with one freestanding layer with patterned metal, single-layer devices with more than one thickness, and two layer devices. Two classes of devices were fabricated with the developed processes. The first class of devices are compliant mechanisms, including bent-beam actuators, thermal isolation platforms and out-of-plane grippers. The second class of devices fabricated are freely moving devices such as hinged plates and gears, which require the use of true kinematic joints, such as scissor hinges, staple hinges and pin joints.

  1. Additive chemistry and distributions in NTD photoresist thin films (United States)

    Thackeray, James; Hong, Chang-Young; Clark, Michael B.


    The lithographic performance of photoresists is a function of the vertical distribution of formulation components, such as photoacid generator (PAG) molecules, in photoresist thin films and how these components undergo chemical modification and migrate within the film during the lithography processing steps. This paper will discuss how GCIB-SIMS depth profiles were used to monitor the PAG and quencher base distributions before and after exposure and post-exposure bake processing steps for different PAG/photoresist formulations. The authors show that the use of surface active quencher in an NTD photoresist leads to better resist profiles, superior DOF and better OPC performance.

  2. Novel SU-8 based vacuum wafer-level packaging for MEMS devices

    DEFF Research Database (Denmark)

    Murillo, Gonzalo; Davis, Zachary James; Keller, Stephan Urs


    This work presents a simple and low-cost SU-8 based wafer-level vacuum packaging method which is CMOS and MEMS compatible. Different approaches have been investigated by taking advantage of the properties of SU-8, such as chemical resistance, optical transparence, mechanical reliability...... and versatility. A novel technique of wafer level adhesive bonding, which uses SU-8 as structural and adhesive material, has been developed and successfully demonstrated. Optical inspection and SEM images were used in order to measure the package lid bending and probe the encapsulation sealing. In addition......, an indirect vacuum level measurement has been carried out by comparing the different quality factors of a test cantilever resonator when this element is packed or unpacked....

  3. Novel SU-8/Ionic Liquid Composite for Tribological Coatings and MEMS

    Directory of Open Access Journals (Sweden)

    Leili Batooli


    Full Text Available Tribology of SU-8 polymer is increasingly relevant due to bursting use of this material in a variety of applications. This study is directed towards introduction and investigation of a novel self-lubricating composite of an ionic liquid (IL in SU-8. The new material can be utilized for fabrication of lubricating polymer coating with tunable surface properties or SU8-made elements for microelectromechanical systems (MEMS with enhanced tribological performance. It is shown that addition of IL drastically alters water affinity of the composite while UV patternability remains unmodified. A lower coefficient of friction and wear has been obtained for two investigated compositions with 4 and 10 wt % ionic liquid.

  4. Studying the mechanism of hybrid nanoparticle EUV photoresists

    KAUST Repository

    Zhang, Ben


    This work focuses on the investigation of dual tone patterning mechanism with hybrid inorganic/organic photoresists. Hafnium oxide (HfO2) modified with acrylic acid was prepared and the influence of electrolyte solutions as well as pH on its particle size change was investigated. The average particle size and zeta potential of the nanoparticles in different electrolyte solutions were measured. The results show that addition of different concentrations of electrolytes changed the hydrodynamic diameter of nanoparticles in water. Increased concentration of tetramethyl ammonium hydroxide (TMAH) caused the zeta potential of nanoparticles to change from positive to negative and its hydrodynamic diameter to increase from 40 nm to 165 nm. In addition, increasing concentration of triflic acid led to the decrease of particle size and zeta potential. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  5. A tapered hollow metallic microneedle array using backside exposure of SU-8 (United States)

    Kim, Kabseog; Park, Daniel S.; Lu, Hong M.; Che, Wooseong; Kim, Kyunghwan; Lee, Jeong-Bong; Ahn, Chong H.


    This paper presents a novel fabrication process for a tapered hollow metallic microneedle array using backside exposure of SU-8, and analytic solutions of critical buckling of a tapered hollow microneedle. An SU-8 mesa was formed on a Pyrex glass substrate and another SU-8 layer, which was spun on top of the SU-8 mesa, was exposed through the backside of the glass substrate. An array of SU-8 tapered pillar structures, with angles in the range of 3.1°-5°, was formed on top of the SU-8 mesa. Conformal electrodeposition of metal was carried out followed by a mechanical polishing using a planarizing polymeric layer. All organic layers were then removed to create a metallic hollow microneedle array with a fluidic reservoir on the backside. Both 200 µm and 400 µm tall, 10 by 10 arrays of metallic microneedles with inner diameters of the tip in the range of 33.6-101 µm and wall thickness of 10-20 µm were fabricated. Analytic solutions of the critical buckling of arbitrary-angled truncated cone-shaped columns are also presented. It was found that a single 400 µm tall hollow cylindrical microneedle made of electroplated nickel with a wall thickness of 20 µm, a tapered angle of 3.08° and a tip inner diameter of 33.6 µm has a critical buckling force of 1.8 N. This analytic solution can be used for square or rectangular cross-sectioned column structures with proper modifications.

  6. Evaluation of Effective Elastic, Piezoelectric, and Dielectric Properties of SU8/ZnO Nanocomposite for Vertically Integrated Nanogenerators Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Neelam Mishra


    Full Text Available A nanogenerator is a nanodevice which converts ambient mechanical energy into electrical energy. A piezoelectric nanocomposite, composed of vertical arrays of piezoelectric zinc oxide (ZnO nanowires, encapsulated in a compliant polymeric matrix, is one of most common configurations of a nanogenerator. Knowledge of the effective elastic, piezoelectric, and dielectric material properties of the piezoelectric nanocomposite is critical in the design of a nanogenerator. In this work, the effective material properties of a unidirectional, unimodal, continuous piezoelectric composite, consisting of SU8 photoresist as matrix and vertical array of ZnO nanowires as reinforcement, are systematically evaluated using finite element method (FEM. The FEM simulations were carried out on cubic representative volume elements (RVEs. Four different types of arrangements of ZnO nanowires and three sizes of RVEs have been considered. The volume fraction of ZnO nanowires is varied from 0 to a maximum of 0.7. Homogeneous displacement and electric potential are prescribed as boundary conditions. The material properties are evaluated as functions of reinforcement volume fraction. The values obtained through FEM simulations are compared with the results obtained via the Eshelby-Mori-Tanaka micromechanics. The results demonstrate the significant effects of ZnO arrangement, ZnO volume fraction, and size of RVE on the material properties.

  7. Humidity influence on the adhesion of SU-8 polymer from MEMS applications

    Directory of Open Access Journals (Sweden)

    Birleanu Corina


    Full Text Available In this paper, the adhesion behaviors of SU-8 polymer thin film from MEMS application were investigated as a function of relative humidity. The adhesion test between the AFM tip and SU-8 polymer have been extensively studied using the atomic force microscope (AFM, for a relative humidity (RH varying between 20 and 90%. The samples for tests are SU-8 polymers hard baked at different temperatures. The hard bake temperature changes the tribo-mechanical properties of polymers. The paper reports the measurements and the modeling of adhesion forces versus humidity in controlled ranges between 20 to 90%RH. To investigate the effect of relative humidity on adhesion for SU-8 polymer hard baked we used an analytical method which encompasses the effect of capillarity as well as the solid-to-solid interaction. While the capillary force expression is considered to be the sum of the superficial tension and the Laplace force for the solid-solid interaction is expressed by the Derjagin, Muller and Toropov (DMT model of solids adhesion. The analytical results obtained are in accordance with those obtained experimentally.

  8. Improved performance of InAs/GaSb strained layer superlattice detectors with SU-8 passivation (United States)

    Kim, H. S.; Plis, E.; Myers, S.; Khoshakhlagh, A.; Gautam, N.; Kutty, M. N.; Sharma, Y. D.; Dawson, L. R.; Krishna, S.


    We report on surface passivation using SU-8 for type-II InAs/GaSb strained layers superlattice (SLS) detectors with a PIN design operating in mid-wave infrared (MWIR) spectral region (λ50% cut-off ~ 4.4 μm). Material growth and characterization, single pixel device fabrication and testing, as well as focal plane array (FPA) processing are described. High quality strain-balanced SLS material with FWHM of 1st SLS satellite peak of 36 arcsec is demonstrated. The electrical and optical performance of devices passivated with SU-8 are reported and compared with those of unpassivated devices. The dark current density of a single pixel device with SU-8 passivation showed four orders of magnitude reduction compared to the device without any passivation. At 77K, the zero-bias responsivity and detectivity are equal to 1.1 A/W and 4 x 1012 Jones at 4μm, respectively, for the SU-8 passivated test pixel on the focal plane array.

  9. Nanochannels in SU-8 with floor and ceiling metal electrodes and integrated microchannels

    NARCIS (Netherlands)

    Nichols, K.P.F.; Eijkel, Jan C.T.; Gardeniers, Johannes G.E.


    Sacrificially etched 2-D nanofluidic channels and nanospaces with integrated floor and ceiling electrodes and arbitrary channel geometries have been demonstrated with channel heights from 20 nm to 400 nm, widths from 800 nm to 40 mm, and lengths up to 3 mm, using SU-8 as the channel structural

  10. Investigation of the bond strength between the photo-sensitive polymer SU-8 and gold

    DEFF Research Database (Denmark)

    Nordström, Maria; Johansson, Alicia; Sánchez Noguerón, E.


    We present the results from a thorough investigation of the bond strength between the photo-polymer SU-8 and Au. The data were obtained by pull-test experiments, below the glass transition temperature of the polymer. The different aspects that we investigated were:(i)the effect of using different...

  11. Dense vertical SU-8 microneedles drawn from a heated mold with precisely controlled volume (United States)

    Xiang, Zhuolin; Wang, Hao; Kanna Murugappan, Suresh; Yen, Shih-Cheng; Pastorin, Giorgia; Lee, Chengkuo


    Drawing lithography technology has recently become a popular technique to fabricate (3D) microneedles. The conventional drawing process shows some limitations in fabricating dense, scale-up and small microneedles. In this study, we demonstrate a new drawing lithography process from a self-loading mold which is able to overcome these challenges. Different from the conventional molds which have difficult alignment and loading issues, a released SU-8 membrane is attached onto a SU-8 coated wafer to generate an innovative self-loading mold. The physically distinct SU-8 colloid in this mold successfully avoids the merging of the microneedle tips in the drawing process. Meanwhile, the same SU-8 colloid in mold can provide microneedles with uniform lengths on a large surface area. Furthermore, a low temperature drawing process with this improved technique prevents sharp tips from bending during the solidification stage. Remarkably, this new drawing lithography technology can fabricate microneedles with various lengths and they are strong enough to penetrate the outermost skin layer, namely the stratum corneum. The spacing between two adjacent microneedles is optimized to maximize the penetration rate through the skin. Histology images and drug diffusion testing demonstrate that microchannels are successfully created and the drugs can permeate the tissue under the skin. The fabricated microneedles are demonstrated to deliver insulin in vivo and lower blood glucose levels, suggesting future possible applications for minimally invasive transdermal delivery of macromolecules.

  12. Integrated SU-8 photonic gas sensors based on PANI polymer devices: Comparison between metrological parameters (United States)

    Airoudj, A.; Bêche, B.; Debarnot, D.; Gaviot, E.; Poncin-Epaillard, F.


    In this work, we have designed and developed three families of integrated photonic sensors for ammonia detection. These photonic sensors are integrated onto single-mode TE 0-TM 0 SU-8 polymer planar waveguides and based on a polyaniline (PANI) sensitive polymer material. The first family relies on the deposit of a PANI-polymethyl methacrylate (PMMA) composite sensitive layer on a given SU-8 waveguide. The second family relies on a PMMA passive layer deposited on the SU-8 waveguide before applying the PANI sensitive layer on the PMMA passive layer. The third family takes advantage of a PANI layer deposited by plasma technique directly onto the SU-8 waveguide. The working principle of such sensors is based on the optical intensity modulation induced within the single-mode waveguide owing to the interaction between the evanescent field and the sensitive layer. The sensing proprieties of these integrated photonic sensors to ammonia gas at room temperature were characterized and the comparison between these different families of photonic sensors is presented. Experimental results show that the sensor based on new plasma-PANI as sensitive layer has the better metrological parameters.

  13. Drift study of SU8 cantilevers in liquid and gaseous environments

    DEFF Research Database (Denmark)

    Tenje, Maria; Keller, Stephan Sylvest; Dohn, Søren


    We present a study of the drift, in terms of cantilever deflections without probe/target interactions, of polymeric SU8 cantilevers. The drift is measured in PBS buffer (pH 7.4) and under vacuum (1 mbar) conditions. We see that the cantilevers display a large drift in both environments. We believ...

  14. Composition and method for removing photoresist materials from electronic components (United States)

    Davenhall, Leisa B.; Rubin, James B.; Taylor, Craig M.


    Composition and method for removing photoresist materials from electronic components. The composition is a mixture of at least one dense phase fluid and at least one dense phase fluid modifier. The method includes exposing a substrate to at least one pulse of the composition in a supercritical state to remove photoresist materials from the substrate.

  15. Metal Oxide Nanoparticle Photoresists for EUV Patterning

    KAUST Repository

    Jiang, Jing


    © 2014SPST. Previous studies of methacrylate based nanoparticle have demonstrated the excellent pattern forming capability of these hybrid materials when used as photoresists under 13.5 nm EUV exposure. HfO2 and ZrO2 methacrylate resists have achieved high resolution (∼22 nm) at a very high EUV sensitivity (4.2 mJ/cm2). Further investigations into the patterning process suggests a ligand displacement mechanism, wherein, any combination of a metal oxide with the correct ligand could generate patterns in the presence of the suitable photoactive compound. The current investigation extends this study by developing new nanoparticle compositions with transdimethylacrylic acid and o-toluic acid ligands. This study describes their synthesis and patterning performance under 248 nm KrF laser (DUV) and also under 13.5 nm EUV exposures (dimethylacrylate nanoparticles) for the new resist compositions.

  16. Photoresists in extreme ultraviolet lithography (EUVL) (United States)

    De Simone, Danilo; Vesters, Yannick; Vandenberghe, Geert


    The evolutionary advances in photosensitive material technology, together with the shortening of the exposure wavelength in the photolithography process, have enabled and driven the transistor scaling dictated by Moore's law for the last 50 years. Today, the shortening wavelength trend continues to improve the chips' performance over time by feature size miniaturization. The next-generation lithography technology for high-volume manufacturing (HVM) is extreme ultraviolet lithography (EUVL), using a light source with a wavelength of 13.5 nm. Here, we provide a brief introduction to EUVL and patterning requirements for sub-0-nm feature sizes from a photomaterial standpoint, discussing traditional and novel photoresists. Emphasis will be put on the novel class of metal-containing resists (MCRs) as well as their challenges from a manufacturing prospective.

  17. Single-shot two-photon exposure of commercial photoresist for the production of three-dimensional structures. (United States)

    Witzgall, G; Vrijen, R; Yablonovitch, E; Doan, V; Schwartz, B J


    We report the use of an amplified femtosecond laser for single-shot two-photon exposure of the commercial photoresist SU-8. By scanning of the focal volume through the interior of the resist, three-dimensional (3-D) structures are fabricated on a shot-by-shot basis. The 800-nm two-photon exposure and damage thresholds are 3.2 and 8.1TW/cm(2), respectively. The nonlinear nature of the two-photon process allows the production of features that are smaller than the diffraction limit. Preliminary results suggest that Ti:sapphire oscillators can achieve single-shot two-photon exposure with thresholds as low as 1.6TW/cm(2) at 700 nm, allowing 3-D structures to be constructed at megahertz repetition rates.

  18. SU-8 Electrothermal Actuators: Optimization of Fabrication and Excitation for Long-Term Use

    Directory of Open Access Journals (Sweden)

    Thomas Winterstein


    Full Text Available In this paper we examine the suitability of SU-8 2000 as a construction material for electrothermal actuators and the actuator stability for long-term operation. The fabrication of SU-8 was optimized for mechanical and thermal stability. Samples with different softbake duration, exposure dose and postbake temperature were evaluated using Fourier-Transform IR-spectroscopy and dynamic-mechanical analysis. The exposure dose and postbake temperature proved to have a strong influence on the cross-linking and the glass transition temperature. A final hardbake levels the effects of the process history. A high degree of crosslinking, a low drop of the dynamic modulus over temperature (30% up to the glass transition temperature 100–140 °C were achieved for SU-8 with an exposure dose of 1500 mJ/cm², a postbake temperature of 95 °C and hardbake of 240 °C. Electrothermal actuators proved to be stable until the end of the experiment after 2400 duty cycles. Actuator deflections up to 55 μm were measured (actuator length: 4 mm for input powers up to 160 mW and a maximum operating temperature of 120 °C. Higher temperatures led to permanent deformations and failure. An offset drift of up to 20% occurs during actuation, but converges after a burn-in phase of about two hours.

  19. Design and fabricate multi channel microfluidic mold on top of glass slide using SU-8 (United States)

    Azman, N. A. N.; Rajapaksha, R. D. A. A.; Uda, M. N. A.; Hashim, U.


    Microfluidic is the study of fluid in microscale. Microfluidics provides miniaturized fluidic networks for processing and analyzing liquids in the nanoliter to milliliter range. Microfluidic device comprises of some essential segments or structure that are micromixer, microchannel and microchamber. The SU-8 mold is known as the most used technique in microfluidic fabrication due to the characteristic of very gooey polymer that can be spread over a thickness. In this study, in order to reduce the fabrication cost, the development and fabrication of SU-8 mold is replace by using a glass plate instead of silicon wafer which is used in the previous research. We designed a microfluidic chip for use with an IDE sensors to conduct multiplex detection of multiple channels. The microfluidic chip was designed to include multiplex detection for pathogen that consists of multiple channels of simultaneous results. The multi-channel microfluidic chip was designed, including the fluid outlet and inlet. A multi-channel microfluidic chip was used for pathogen detection. This paper sum up the fabrication of lab SU-8 mold using glass slide.

  20. SU-8 based microdevices to study self-induced chemotaxis in 3D microenvironments

    Directory of Open Access Journals (Sweden)

    Jose Maria Ayuso


    Full Text Available Tissues are complex three-dimensional structures in which cell behaviour is frequently guided by chemotactic signals. Although starvation and nutrient restriction induce many different chemotactic processes, the recreation of such conditions in vitro remains difficult when using standard cell culture equipment. Recently, microfluidic techniques have arisen as powerful tools to mimic such physiological conditions. In this context, microfluidic three-dimensional cell culture systems require precise control of cell/hydrogel location because samples need to be placed within a microchamber without obstruction of surrounding elements. In this article, SU-8 is studied as structural material for the fabrication of complex cell culture devices due to its good mechanical properties, low gas permeability and sensor integration capacity. In particular, this manuscript presents a SU-8 based microdevice designed to create self-induced medium starvation, based on the combination of nutrient restriction and natural cell metabolism. Results show a natural migratory response towards nutrient source, showing how cells adapt to their own microenvironment modifications. The presented results demonstrate the SU-8 potential for microdevice fabrication applied to cell culture.

  1. SU-8 as Hydrophobic and Dielectric Thin Film in Electrowetting-on-Dielectric Based Microfluidics Device

    Directory of Open Access Journals (Sweden)

    Vijay Kumar


    Full Text Available Electrowetting-on-dielectric (EWOD based droplet actuation in microfluidic chip is designed and fabricated. EWOD is used as on-chip micro-pumping scheme for moving fluid digitally in Lab-on-a-chip devices. For enabling this scheme, stacked deposition of thin dielectric and hydrophobic layer in that order between microchannel and electrodes is done. The present paper investigates the potential use of SU-8 as hydrophobic layer in conjunction of acting as dielectric in the device. The objective for the investigation is to lower the cost and a thin simplification in fabrication process of EWOD-based devices. We have done design and optimization of dimensions of electrode array including gap between arrays for EWOD micropump. Design and optimization are carried out in CoventorWare. The designing is followed by fabrication of device and analysis for droplet motion. The fabrication of the device includes array of electrodes over the silicon surface and embedding them in hydrophobic SU-8 layer. Water droplet movement in the order of microliter of spherical shape is demonstrated. It has been shown that an SU-8 microchannel in the current design allows microfluidic flow at tens of voltages comparable with costlier and more complicated to fabricate designs reported in the literature.

  2. PMMA to SU-8 Bonding for Polymer Based Lab-on -a-chip Systems with Integrated Optics

    DEFF Research Database (Denmark)

    Clausen, Bjarne


    An adhesive bonding technique for wafer-level sealing of SU-8 based lab-on-a-chip microsystems with integrated optical components is presented. Microfluidic channels and optical components, e.g. waveguides, are fabricated in cross-linked SU-8 and sealed with a Pyrex glass substrate by means...

  3. SU-8 cantilevers for bio/chemical sensing; Fabrication, characterisation and development of novel read-out methods

    DEFF Research Database (Denmark)

    Nordström, M.; Keller, Stephan Urs; Lillemose, Michael


    Here, we present the activities within our research group over the last five years with cantilevers fabricated in the polymer SU-8. We believe that SU-8 is an interesting polymer for fabrication of cantilevers for bio/chemical sensing due to its simple processing and low Young's modulus. We show...

  4. Simulation and experimental validation of a SU-8 based PCR thermocycler chip with integrated heaters and temperature sensor

    DEFF Research Database (Denmark)

    El-Ali, Jamil; Perch-Nielsen, Ivan R.; Poulsen, Claus Riber


    C/s, respectively, the performance of the chip is comparable with the best silicon micromachined PCR chips presented in the literature. The SU-8 chamber surface was found to be PCR compatible by amplification of yeast gene ribosomal protein S3 and Campylobacter gene cadF. The PCR compatibility of the chamber......We present a SU-8 based polymerase chain reaction (PCR) chip with integrated platinum thin film heaters and temperature sensor. The device is fabricated in SU-8 on a glass substrate. The use of SU-8 provides a simple microfabrication process for the PCR chamber, controllable surface properties...... and can allow on chip integration to other SU-8 based functional elements. Finite element modeling (FEM) and experiments show that the temperature distribution in the PCR chamber is homogeneous and that the chip is capable of fast thermal cycling. With heating and cooling rates of up to 50 and 30 degrees...

  5. Chemical changes in hybrid photoresists before and after exposure by in situ NEXAFS analysis (United States)

    Fallica, Roberto; Watts, Benjamin; Della Giustina, Gioia; Brigo, Laura; Brusatin, Giovanna; Ekinci, Yasin


    Due to its chemical specificity, the near edge X-ray absorption fine structure spectroscopy is an interesting technique to study the changes in hybrid organic-inorganic photoresists. In this work, we analyzed the chemical changes occurring in photoresists synthesized from organically modified precursors and transition metal alkoxides by sol-gel route. These systems are nonchemically amplified resists for ultraviolet, extreme ultraviolet, and electron beam lithography. They are based on Si, Zr, and Ti oxides or a combination of these. The experiments were conducted at the PolLux beamline of the Swiss Light Source, by a scanning transmission X-ray microscopy, which combines the spatially-resolved microscopy and fine structure spectroscopy at once. The absorption spectra were collected in the energy range of the carbon edge (≍ 290 eV) before and after in situ exposure of the photoresists to 500 eV photons. The variations in peak intensity after exposure reveal the changes in the chemical environment of carbon and the chemical configuration of the organic ligands, regardless of the inorganic part. It was found that the photon exposure induced sizable photodegradation or photopolymerization of organic groups (phenyl or methyl methacrylate, respectively). These mechanisms contribute to the foundation for the exposure reaction in negative-tone hybrid photoresists. Interestingly, it was also found that the detachment of the phenyl ligand occurs in a variety of possible pathways to condensation. We believe that our results and approach can provide a better understanding of photochemistry of resists, in particular for extreme ultraviolet lithography.

  6. Photoresist shrinkage effects in 16 nm node extreme ultraviolet (EUV) photoresist targets (United States)

    Bunday, Benjamin; Montgomery, Cecilia; Montgomery, Warren; Cepler, Aron


    Photoresist shrinkage (i.e., line slimming) is an important systematic uncertainty source in critical dimension-scanning electron microscope (CD-SEM) metrology of lithographic features [1] [2] [3] [4] [5]. It influences both the precision and the accuracy of CD-SEM measurements, while locally damaging the sample. Minimization or elimination of shrinkage is desirable, yet elusive. This error source will be a factor in CD-SEM metrology on polymer materials in EUV lithography. Recent work has demonstrated improved understanding of the trends in the shrinkage response depending on electron beam and target parameters in static measurements [2] [3] [4] [5] [6]. Some research has highlighted a second mode of shrinkage that is apparent over time and progresses as a function of time between consecutive measurements, a form of "dynamic shrinkage" that appears to be activated by electron beam, in which the activated feature perpetually and logarithmically shrinks [7] [8]. Another work has demonstrated that as pitches continue to get smaller with resulting reductions in spaces between lines, charging may emerge as an additional, competing, unpredictable error source for CD-SEM metrology on dense photoresist features, an issue that is predicted to become more common as these spaces become more confined [9]. In this work, we explore the static shrinkage behaviors of various EUV photoresists into the 16 nm half-pitch node, with samples generated using the advanced EUV lithography capable of generating such tight pitches [10]. Dynamic shrinkage behavior was explored on these materials last year [15]. The static shrinkage behaviors will be validated to show compliance with the SEMATECH shrinkage model [5] [6] on small EUV resist features. Using the results of the model fits, a simulation study will predict the shrinkage trends at future nodes. Further studies will confirm whether or not charging phenomena are observable, and the beginning of a charging simulation study will be

  7. Fabrication of thin SU-8 cantilevers: initial bending, release and time stability

    DEFF Research Database (Denmark)

    Keller, Stephan Urs; Haefliger, D.; Boisen, Anja


    development of the thin SU-8 film resulted in reduced cantilever bending due to removal of residual stress gradients. Further, improved time-stability of the devices was achieved due to the enhanced cross-linking of the polymer. A post-exposure bake at a temperature T-PEB = 50 degrees C followed by a hard...... bake at T-HB = 90 degrees C proved to be optimal to ensure low cantilever bending and low rotational deformation due to excellent device release and low change of these properties with time. With the optimized process, the reproducible fabrication of arrays with 2 mu m thick cantilevers with a length...

  8. Development of vertical SU-8 microneedles for transdermal drug delivery by double drawing lithography technology. (United States)

    Xiang, Zhuolin; Wang, Hao; Pant, Aakanksha; Pastorin, Giorgia; Lee, Chengkuo


    Polymer-based microneedles have drawn much attention in transdermal drug delivery resulting from their flexibility and biocompatibility. Traditional fabrication approaches are usually time-consuming and expensive. In this study, we developed a new double drawing lithography technology to make biocompatible SU-8 microneedles for transdermal drug delivery applications. These microneedles are strong enough to stand force from both vertical direction and planar direction during penetration. They can be used to penetrate into the skin easily and deliver drugs to the tissues under it. By controlling the delivery speed lower than 2 μl/min per single microneedle, the delivery rate can be as high as 71%.

  9. Micro-particle filter made in SU-8 for biomedical applications

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole; Keller, Stephan Urs; Fetz, Stefanie


    We have integrated a micro-particle filter in a polymer cantilever to filter micro-particles from a fluid while simultaneously measuring the amount of filtered particles. In a 3,8 mum thick SU-8 cantilever a filter was integrated with pore sizes between 3 and 30 mum. The chip was inserted...... in a microfluidic system and water with differently sized polystyrene beads was pumped through the filter. Particles which are larger than the pore sizes, cannot pass the filter and will increase the flow resistance of the cantilever. With more and more captured particles the cantilever starts to deflect, which can...

  10. A SU-8/PDMS hybrid microfluidic device with integrated optical fibers for online monitoring of lactate. (United States)

    Wu, Min-Hsien; Cai, Haoyuan; Xu, Xia; Urban, Jill P G; Cui, Zhan-Feng; Cui, Zheng


    A microfluidic device with integrated optical fibres was developed for online monitoring of lactate. The device consists of a SU-8 waveguide, microfluidic channels and grooves for the insertion of optic fibres. It was fabricated by one-step photolithography of SU-8 polymer resist. Different channel widths (50-300 microm) were tested in terms of detection sensitivity. A wide range of flow rates were applied to investigate the influence of flow rate on signal fluctuations. The separation between optical fibre sensor and microfluidic channel and the width of fluidic channel have been optimized to maximize the detection sensitivity. It was revealed that 250 microm of channel width is the optimum light path length for a compromise between detection sensitivity and interference of ambient light. The independence of detection signals on flow rates was demonstrated within the range of flow rate (0.5-5 ml/hr) tested. Compared with conventional lactate detection, the device is proved to have high accuracy, relatively low limit of detection (50 mg/L) and reasonably fast response time (100 sec). The fabrication of device is simple and low cost. The present work has provided some fundamental data for further system optimization to meet specific detection requirements.

  11. Inkjet Printing of High Aspect Ratio Superparamagnetic SU-8 Microstructures with Preferential Magnetic Directions

    Directory of Open Access Journals (Sweden)

    Loïc Jacot-Descombes


    Full Text Available Structuring SU-8 based superparamagnetic polymer composite (SPMPC containing Fe3O4 nanoparticles by photolithography is limited in thickness due to light absorption by the nanoparticles. Hence, obtaining thicker structures requires alternative processing techniques. This paper presents a method based on inkjet printing and thermal curing for the fabrication of much thicker hemispherical microstructures of SPMPC. The microstructures are fabricated by inkjet printing the nanoparticle-doped SU-8 onto flat substrates functionalized to reduce the surface energy and thus the wetting. The thickness and the aspect ratio of the printed structures are further increased by printing the composite onto substrates with confinement pedestals. Fully crosslinked microstructures with a thickness up to 88.8 μm and edge angle of 112° ± 4° are obtained. Manipulation of the microstructures by an external field is enabled by creating lines of densely aggregated nanoparticles inside the composite. To this end, the printed microstructures are placed within an external magnetic field directly before crosslinking inducing the aggregation of dense Fe3O4 nanoparticle lines with in-plane and out-of-plane directions.

  12. Development of vertical SU-8 microtubes integrated with dissolvable tips for transdermal drug delivery. (United States)

    Xiang, Zhuolin; Wang, Hao; Pant, Aakanksha; Pastorin, Giorgia; Lee, Chengkuo


    Polymer-based microneedles have drawn much attention in the transdermal drug delivery resulting from their flexibility and biocompatibility. Traditional fabrication approach deploys various kinds of molds to create sharp tips at the end of needles for the penetration purpose. This approach is usually time-consuming and expensive. In this study, we developed an innovative fabrication process to make biocompatible SU-8 microtubes integrated with biodissolvable maltose tips as novel microneedles for the transdermal drug delivery applications. These microneedles can easily penetrate the skin's outer barrier represented by the stratum corneum (SC) layer. The drug delivery device of mironeedles array with 1000 μm spacing between adjacent microneedles is proven to be able to penetrate porcine cadaver skins successfully. The maximum loading force on the individual microneedle can be as large as 7.36 ± 0.48N. After 9 min of the penetration, all the maltose tips are dissolved in the tissue. Drugs can be further delivered via these open biocompatible SU-8 microtubes in a continuous flow manner. The permeation patterns caused by the solution containing Rhodamine 110 at different depths from skin surface were characterized via a confocal microscope. It shows successful implementation of the microneedle function for fabricated devices.

  13. Dielectric properties of ligand-modified gold nanoparticle/SU-8 photopolymer based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Toor, Anju, E-mail: [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); So, Hongyun, E-mail: [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Pisano, Albert P. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093 (United States)


    Highlights: • Ligand-modified gold NP/SU-8 nanocomposites were synthesized and demonstrated. • Particle agglomeration and dispersion were characterized with different NPs concentration. • Nanocomposites showed higher average dielectric permittivity compared to SU-8 only. • Relatively lower dielectric loss (average 0.09 at 1 kHz) was achieved with 10 % w/w NPs. - Abstract: This article reports the enhanced dielectric properties of a photodefinable polymer nanocomposite material containing sub–10 nm coated metal nanoparticles (NPs). The surface morphology of the synthesized dodecanethiol-functionalized gold NPs was characterized using the transmission electron microscopy (TEM). We investigated the particle agglomeration and dispersion during the various stages of the nanocomposite synthesis using TEM. Physical properties such as dielectric permittivity and dielectric loss were measured experimentally. The dependence of the dielectric permittivity and loss tangent on the particle concentration, and frequency was studied. Nanocomposite films showed an approximately three times enhancement in average dielectric constant over the polymer base value and an average dielectric loss of 0.09 at 1 kHz, at a filler loading of 10% w/w.

  14. A two-step sealing-and-reinforcement SU8 bonding paradigm for the fabrication of shallow microchannels (United States)

    Mehboudi, Aryan; Yeom, Junghoon


    Adhesive bonding is a key technique to create microfluidic devices when two separate substrates are used to form microchannels. Among many adhesives explored in microchannel fabrication, SU8 has been widely used as an adhesive layer for sealing the microchannel sidewalls. The majority of the available SU8-based bonding methods, however, suffer from the difficulties associated with sealing of two important types of the microchannel architecture: (1) shallow microchannels with small patterns on a large area, and (2) microchannels with ultra-low aspect ratios (e.g. 6 mm in width and 2~μ m in height). In this paper, a new bonding paradigm based upon the low-temperature and low-pressure SU8 bonding, consisting of two steps of sealing using a thin-SU8-coated PET film and bonding reinforcement using a SU8-coated glass slide, is proposed to resolve the aforementioned difficulties. Since it does not need complicated instruments such as a wafer bonding machine and a lamination device, the developed bonding paradigm is convenient and economical. We successfully demonstrate the compatibility of the proposed bonding paradigm with the two microchannel fabrication approaches based on the glass wet etching and the SU8 photo-lithography, where small microchannels with the innermost surfaces fully made of SU8 are obtained. A theoretical model is employed to better investigate the flow characteristics and the structural behavior of the microchannel including the PET film deformation, strain and von Mises stress distributions, bonding strength, etc. Moreover, we demonstrate the fabrication of the multi-height deep–shallow microchannel sidewalls and their sealing using the SU8-coated PET film. Finally, as a proof-of-concept device, a microfluidic filter consisting of the double-height deep–shallow microchannel is fabricated for separation of 3 µm and 10 µm particles.

  15. Analytical techniques for mechanistic characterization of EUV photoresists (United States)

    Grzeskowiak, Steven; Narasimhan, Amrit; Murphy, Michael; Ackerman, Christian; Kaminsky, Jake; Brainard, Robert L.; Denbeaux, Greg


    Extreme ultraviolet (EUV, 13.5 nm) lithography is the prospective technology for high volume manufacturing by the microelectronics industry. Significant strides towards achieving adequate EUV source power and availability have been made recently, but a limited rate of improvement in photoresist performance still delays the implementation of EUV. Many fundamental questions remain to be answered about the exposure mechanisms of even the relatively well understood chemically amplified EUV photoresists. Moreover, several groups around the world are developing revolutionary metal-based resists whose EUV exposure mechanisms are even less understood. Here, we describe several evaluation techniques to help elucidate mechanistic details of EUV exposure mechanisms of chemically amplified and metal-based resists. EUV absorption coefficients are determined experimentally by measuring the transmission through a resist coated on a silicon nitride membrane. Photochemistry can be evaluated by monitoring small outgassing reaction products to provide insight into photoacid generator or metal-based resist reactivity. Spectroscopic techniques such as thin-film Fourier transform infrared (FTIR) spectroscopy can measure the chemical state of a photoresist system pre- and post-EUV exposure. Additionally, electrolysis can be used to study the interaction between photoresist components and low energy electrons. Collectively, these techniques improve our current understanding of photomechanisms for several EUV photoresist systems, which is needed to develop new, better performing materials needed for high volume manufacturing.

  16. Applications of SU-8 in the development of a Single Ion Hit Facility

    Energy Technology Data Exchange (ETDEWEB)

    Arteaga-Marrero, N. [Division of Nuclear Physics, Department of Physics, Lund University, Professorsgatan 1, Box 118, SE-22100 Lund (Sweden)], E-mail:; Astromskas, G. [Division of Solid State Physics, Department of Physics, Lund University, Professorsgatan 1, Box 118, SE-22100 Lund (Sweden); Olsson, M.G. [Department of Infection Medicine, Lund University, Soelvegatan 19, B14, SE-22184 Lund (Sweden); Elfman, M.; Kristiansson, P.; Nilsson, E.J.C.; Nilsson, C.; Pallon, J. [Division of Nuclear Physics, Department of Physics, Lund University, Professorsgatan 1, Box 118, SE-22100 Lund (Sweden)


    The Lund Nuclear Microprobe (LNM) has been adapted to be used as a Single Ion Hit Facility (SIHF) for proton cell irradiation experiments at low dose. In order to test the capabilities of the system, Ni dot arrays and artificial cells have been fabricated with the photopolymer SU-8 and common lithographic techniques. The primary purpose of the Ni dot arrays was to determine the targeting accuracy of the beam in vacuum and in air. Additionally, this sample was employed to evaluate the system performance during cell target irradiation experiments. The Ni dot arrays were also used for beam characterization. The artificial cells were originally fabricated to test the software for cell recognition and localization, developed and implemented at the LNM. However, this sample became very functional to make small adjustments at the irradiation chamber for cell irradiation experiments. A description of the samples, fabrication procedure and applications are presented in this paper.

  17. Simulation of a low frequency Z-axis SU-8 accelerometer in coventorware and MEMS+

    KAUST Repository

    Carreno, Armando Arpys Arevalo


    This paper presents the simulation of a z-axis SU-8 capacitive accelerometer. The study consists of a modal analysis of the modeled accelerometer, a study relating capacitance to acceleration, capacitance to deflection, an effective spring constant calculation, and a comparison of results achieved using CoventorWare® ANALYZER™ and MEMS+®. A fabricated energy harvester design from [1] was used for modeling and simulation in this study, with a four spring attachment of a 650μm×650μm; ×110μm proof mass of 4.542×10-8 kg. At rest, the spacing between electrodes is 4μm along the z-axis, and at 1.5g acceleration, there is 1.9μm spacing between electrodes, at which point pull in occurs for a 1V voltage. © 2013 IEEE.

  18. SU-8 Based MEMS Process with Two Metal Layers using α-Si as a Sacrificial Material

    KAUST Repository

    Ramadan, Khaled S.


    Polymer based microelectromechanical systems (MEMS) micromachining is finding more interest in research and applications. This is due to its low cost and less time processing compared with silicon MEMS. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic devices. In addition to being processed with low cost, it is a biocompatible material with good mechanical properties. Also, amorphous silicon (α-Si) has found use as a sacrificial layer in silicon MEMS applications. α-Si can be deposited at large thicknesses for MEMS applications and also can be released in a dry method using XeF2 which can solve stiction problems related to MEMS applications. In this thesis, an SU-8 MEMS process is developed using amorphous silicon (α-Si) as a sacrificial layer. Electrostatic actuation and sensing is used in many MEMS applications. SU-8 is a dielectric material which limits its direct use in electrostatic actuation. This thesis provides a MEMS process with two conductive metal electrodes that can be used for out-of-plane electrostatic applications like MEMS switches and variable capacitors. The process provides the fabrication of dimples that can be conductive or non-conductive to facilitate more flexibility for MEMS designers. This SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were tuned for two sets of thicknesses which are thin (5-10μm) and thick (130μm). Chevron bent-beam structures and different suspended beams (cantilevers and bridges) were fabricated to characterize the SU-8 process through extracting the density, Young’s Modulus and the Coefficient of Thermal Expansion (CTE) of SU-8. Also, the process was tested and used as an educational tool through which different MEMS structures were fabricated including MEMS switches, variable capacitors and thermal actuators.

  19. Converting printed wiring product processing to aqueous processable dry film photoresist. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Goldammer, S.E.


    Fully aqueous processable dry film photoresists were evaluated to determine which dry film in the Federal Manufacturing and Technologies printed wiring board facility performed the best. The photoresists were chosen for their compatibility in alkaline etching, copper electroplating, and tin-lead electroplating. The processing evaluation included both single layer and double layer dry film photoresist for pattern plating.

  20. Photolithography of thick photoresist coating for electrically controlled liquid crystal photonic bandgap fibre devices

    DEFF Research Database (Denmark)

    Wei, Lei; Khomtchenko, Elena; Alkeskjold, Thomas Tanggaard


    Thick photoresist coating for electrode patterning in an anisotropically etched V-groove is investigated for electrically controlled liquid crystal photonic bandgap fibre devices. The photoresist step coverage at the convex corners is compared with and without soft baking after photoresist spin...

  1. Aqueous-based thick photoresist removal for bumping applications (United States)

    Moore, John C.; Brewer, Alex J.; Law, Alman; Pettit, Jared M.


    Cleaning processes account for over 25% of processing in microelectronic manufacturing [1], suggesting electronics to be one of the most chemical intensive markets in commerce. Industry roadmaps exist to reduce chemical exposure, usage, and waste [2]. Companies are encouraged to create a safer working environment, or green factory, and ultimately become certified similar to LEED in the building industry [3]. A significant step in this direction is the integration of aqueous-based photoresist (PR) strippers which eliminate regulatory risks and cut costs by over 50%. One of the largest organic solvent usages is based upon thick PR removal during bumping processes [4-6]. Using market projections and the benefits of recycling, it is estimated that over 1,000 metric tons (mt) of residuals originating from bumping processes are incinerated or sent to a landfill. Aqueous-based stripping would eliminate this disposal while also reducing the daily risks to workers and added permitting costs. Positive-tone PR dissolves in aqueous strippers while negative-tone systems are lifted-off from the substrate, bumps, pillars, and redistribution layers (RDL). While the wafers are further processed and rinsed, the lifted-off PR is pumped from the tank, collected onto a filter, and periodically back-flushed to the trash. The PR solids become a non-hazardous plastic waste while the liquids are mixed with the developer stream, neutralized, filtered, and in most cases, disposed to the sewer. Regardless of PR thickness, removal processes may be tuned to perform in <15min, performing at rates nearly 10X faster than solvents with higher bath lives. A balanced formula is safe for metals, dielectrics, and may be customized to any fab.

  2. Development of an SU-8 MEMS process with two metal electrodes using amorphous silicon as a sacrificial material

    KAUST Repository

    Ramadan, Khaled S.


    This work presents an SU-8 surface micromachining process using amorphous silicon as a sacrificial material, which also incorporates two metal layers for electrical excitation. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic applications due to its mechanical properties, biocompatibility and low cost. Amorphous silicon is used as a sacrificial layer in MEMS applications because it can be deposited in large thicknesses, and can be released in a dry method using XeF2, which alleviates release-based stiction problems related to MEMS applications. In this work, an SU-8 MEMS process was developed using ;-Si as a sacrificial layer. Two conductive metal electrodes were integrated in this process to allow out-of-plane electrostatic actuation for applications like MEMS switches and variable capacitors. In order to facilitate more flexibility for MEMS designers, the process can fabricate dimples that can be conductive or nonconductive. Additionally, this SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were optimized for two sets of thicknesses: thin (5-10 m) and thick (130 m). The process was tested fabricating MEMS switches, capacitors and thermal actuators. © 2013 IOP Publishing Ltd.

  3. Removal of ion-implanted photoresists on GaAs using two organic solvents in sequence

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Eunseok; Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo, E-mail:


    Highlights: • Two-step photoresist removal process using two organic solvents was developed. • Photoresist on trench patterned GaAs was removed by two-step sequence. • Acetonitrile with dimethyl sulfoxide removed implanted photoresists at 30 °C. • Affinity and permeability of solvent through photoresist determine photoresist removal. - Abstract: Organic solvents can effectively remove photoresists on III–V channels without damage or etching of the channel material during the process. In this study, a two-step sequential photoresist removal process using two different organic solvents was developed to remove implanted ArF and KrF photoresists at room temperature. The effects of organic solvents with either low molar volumes or high affinities for photoresists were evaluated to find a proper combination that can effectively remove high-dose implanted photoresists without damaging GaAs surfaces. The performance of formamide, acetonitrile, nitromethane, and monoethanolamine for the removal of ion-implanted ArF and KrF photoresists were compared using a two-step sequential photoresist removal process followed by treatment in dimethyl sulfoxide (DMSO). Among the various combinations, the acetonitrile + DMSO two-step sequence exhibited the best removal of photoresists that underwent ion implantation at doses of 5 × 10{sup 13}–5 × 10{sup 15} atoms/cm{sup 2} on both flat and trench-structured GaAs surfaces. The ability of the two-step process using organic solvents to remove the photoresists can be explained by considering the affinities of solvents for a polymer and its permeability through the photoresist.

  4. A highly integrated vertical SU8 valve for stepwise in-series reactions (United States)

    Calvo, V.; Ezkerra, A.; Elizalde, J.; Fernández, L. J.; Berganzo, J.; Mayora, K.; Ruano-López, J. M.


    Stepwise performance of reactions demands highly integrated microfluidic control. The vertical valve presented in this work allows performing reactions in cascade with reduced control requirements, by controlling the rupture of an SU8 wall that separates a chamber from an adjacent evacuation channel. Owing to its vertical construction, the valve can be readily integrated into any geometry with a low increase in footprint. Two valve approaches are presented, which differ in the location of the rupture region, the breaking pressures and the size of the fluidic path open. Breaking the wall about its upper end has proven to be more limited in terms of geometry and resulting gap size, whereas breaking the wall about its root opens a wider fluidic path that allows smooth filling of downstream chambers. Following these conclusions, a sequence of two reactions has been demonstrated, using a wall-valve-regulated double-chamber device. The chosen protocol, DNA concentration, elution and transport, has been successfully accomplished, as evidenced by positive on-chip polymerase chain reaction in a second double-chamber device.

  5. MEMS flexible artificial basilar membrane fabricated from piezoelectric aluminum nitride on an SU-8 substrate (United States)

    Jang, Jongmoon; Jang, Jeong Hun; Choi, Hongsoo


    In this paper, we present a flexible artificial basilar membrane (FABM) that mimics the passive mechanical frequency selectivity of the basilar membrane. The FABM is composed of a cantilever array made of piezoelectric aluminum nitride (AlN) on an SU-8 substrate. We analyzed the orientations of the AlN crystals using scanning electron microscopy and x-ray diffraction. The AIN crystals are oriented in the c-axis (0 0 2) plane and effective piezoelectric coefficient was measured as 3.52 pm V-1. To characterize the frequency selectivity of the FABM, mechanical displacements were measured using a scanning laser Doppler vibrometer. When electrical and acoustic stimuli were applied, the measured resonance frequencies were in the ranges of 663.0-2369 Hz and 659.4-2375 Hz, respectively. These results demonstrate that the mechanical frequency selectivity of this piezoelectric FABM is close to the human communication frequency range (300-3000 Hz), which is a vital feature of potential auditory prostheses.

  6. Study of functional viability of SU-8-based microneedles for neural applications (United States)

    Fernández, Luis J.; Altuna, Ane; Tijero, Maria; Gabriel, Gemma; Villa, Rosa; Rodríguez, Manuel J.; Batlle, Montse; Vilares, Roman; Berganzo, Javier; Blanco, F. J.


    This paper presents the design, fabrication, packaging and first test results of SU-8-based microneedles for neural applications. By the use of photolithography, sputtering and bonding techniques, polymer needles with integrated microchannels and electrodes have been successfully fabricated. The use of photolithography for the patterning of the fluidic channel integrated in the needle allows the design of multiple outlet ports at the needle tip, minimizing the possibility of being blocked by the tissue. Furthermore, the flexibility of the polymer reduces the risk of fracture and tissue damage once the needle is inserted, while it is still rigid enough to allow a perfect insertion into the neural tissue. Fluidic and electric characterization of the microneedles has shown their viability for drug delivery and monitoring in neural applications. First drug delivery tests in ex vivo tissue demonstrated the functional viability of the needle to deliver drugs to precise points. Furthermore, in vivo experiments have demonstrated lower associated damages during insertion than those by stereotaxic standard needles.

  7. New photoresist stripper and a system for recycling it (United States)

    Nishida, Hideki; Kikuchi, Hiroshi; Yano, Kensuke; Matsuda, Hiroyasu


    Although it is hard to strip away the photoresist layer damaged during the etching process in manufacturing liquid crystal display devices, monoethynoloamine (MEA) was found to have excellent photoresist stripping characteristics. Crosslinked novolak resin is easily dissolved in a MEA solution because MEA has a large cohesive energy, a strong affinity for novolak, and a small molecular weight. Pure MEA can be recycled with high yield by using a simple system that has short multiple-pipe distillation columns that have high heat-transfer efficiency. The pipes in our distillation system are made of 304 stainless steel because this material was found to resist corrosion in an aqueous MEA solution better than 316L stainless or Cu. This recycling system has been operating in production lines for more than two years without showing any signs of trouble.

  8. Film quantum yields of EUV& ultra-high PAG photoresists

    Energy Technology Data Exchange (ETDEWEB)

    Hassanein, Elsayed; Higgins, Craig; Naulleau, Patrick; Matyi, Richard; Gallatin, Greg; Denbeaux, Gregory; Antohe, Alin; Thackery, Jim; Spear, Kathleen; Szmanda, Charles; Anderson, Christopher N.; Niakoula, Dimitra; Malloy, Matthew; Khurshid, Anwar; Montgomery, Cecilia; Piscani, Emil C.; Rudack, Andrew; Byers, Jeff; Ma, Andy; Dean, Kim; Brainard, Robert


    Base titration methods are used to determine C-parameters for three industrial EUV photoresist platforms (EUV-2D, MET-2D, XP5496) and twenty academic EUV photoresist platforms. X-ray reflectometry is used to measure the density of these resists, and leads to the determination of absorbance and film quantum yields (FQY). Ultrahigh levels ofPAG show divergent mechanisms for production of photo acids beyond PAG concentrations of 0.35 moles/liter. The FQY of sulfonium PAGs level off, whereas resists prepared with iodonium PAG show FQY s that increase beyond PAG concentrations of 0.35 moles/liter, reaching record highs of 8-13 acids generatedlEUV photons absorbed.

  9. Suspended microstructures of epoxy based photoresists fabricated with UV photolithography

    DEFF Research Database (Denmark)

    Hemanth, Suhith; Anhøj, Thomas Aarøe; Caviglia, Claudia


    In this work we present an easy, fast, reliable and low cost microfabrication technique for fabricating suspended microstructures of epoxy based photoresistswith UV photolithography. Two different fabrication processes with epoxy based resins (SU-8 and mr-DWL) using UV exposures at wavelengths...

  10. Design and study of aqueous processable positive-tone photoresists (United States)

    Yamada, Shintaro; Owens, Jordan; Rager, Timo; Nielsen, Morton; Byers, Jeff D.; Willson, C. Grant


    Interest in developing materials with reduced environmental impact has led us to design resist formulations that can be cast from and developed with aqueous media. A water soluble chemically amplified positive tone photoresist based on thermal decarboxylation of a half ester of malonic acid has been designed. Two solubility switches are required for this application. Sequential volatilization of ammonia followed by decarboxylation of a malonic acid gives the first solubility switch and an acid catalyzed thermolysis of an acid labile protecting group gives the second. The thermal stability of the acid labile protecting group is critical in this design. Tert-butyl esters decompose during the decarboxylation process resulting in poor imaging contrast. Polymers bearing isobornyl esters are more thermally stable, and show excellent reaction selectivity between the decarboxylation and the thermolysis of the ester. Preliminary imaging of this system provided 1 micrometer resolution with 248 nm exposure and standard TMAH developer. The dry etch stability of the photoresist films is comparable to a conventional photoresist APEX-ER.

  11. Chemical metallization of KMPR photoresist polymer in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Zeb, Gul [MiQro Innovation Collaborative Centre (C2MI), 45, boul. de l' Aéroport, Bromont, QC, J2L 1S8 (Canada); Mining & Materials Engineering, McGill University, 3610,University Street, Montreal, QC, H3A 0C5 (Canada); Duong, Xuan Truong [Department of Mechanical Engineering, Ecole polytechnique de Montréal, Montréal, QC, H3C 3T5 (Canada); Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam); Vu, Ngoc Pi; Phan, Quang The; Nguyen, Duc Tuong; Ly, Viet Anh [Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam); Salimy, Siamak [ePeer Review LLC, 145 Pine Haven Shores Rd, Suite 1000-X, Shelburne, VT 05482 (United States); Le, Xuan Tuan, E-mail: [MiQro Innovation Collaborative Centre (C2MI), 45, boul. de l' Aéroport, Bromont, QC, J2L 1S8 (Canada); Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam)


    Highlights: • Electroless deposition of Ni-B film on KMPR photoresist polymer insulator with excellent adhesion has been achieved. • This metallization has been carried out in aqueous solutions at low temperature. • Polyamine palladium complexes grafts serve as seeds for the electroless plating on KMPR. • This electroless metallization process is simple, industrially feasible, chromium-free and environment-friendly. - Abstract: While conventional methods for preparing thin films of metals and metallic alloys on insulating substrates in the field of microelectromechanical systems (MEMS) include vapor deposition techniques, we demonstrate here that electroless deposition can be considered as an alternate efficient approach to metallize the surface of insulating substrates, such as KMPR epoxy photoresist polymer. In comparison with the physical and chemical vapor deposition methods, which are well-established for metallization of photoresist polymers, our electroless nickel plating requires only immersing the substrates into aqueous solutions in open air at low temperatures. Thin films of nickel alloy have been deposited electrolessly on KMPR surface, through a cost-effective and environmental chromium-free process, mediated through direct grafting of amine palladium complexes in aqueous medium. This covalent organic coating provides excellent adhesion between KMPR and the nickel film and allows better control of the palladium catalyst content. Covalent grafting and characterization of the deposited nickel film have been carried out by means of Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy techniques.

  12. Contact printed masks for 3D microfabrication in negative resists


    Häfliger, Daniel; Boisen, Anja


    We present a process based on contact printed shadow masks for three dimensional microfabrication of soft and sensitive overhanging membranes in SU-8. A metal mask is transferred onto unexposed SU-8 from an elastomer stamp made of polydimethylsiloxane. This mask is subsequently embedded into the negative resist to protect buried material from UV-exposure. Unlike direct evaporation-deposition of a mask onto the SU-8, printing avoids high stress and radiation, thus preventing resist wrinkling a...

  13. Temporal evolution of as-developed line and space photoresist profiles during etch (United States)

    Lane, Barton; Ventzek, Peter; Ranjan, Alok; Rastogi, Vinayak; Yoshikawa, Jun


    We discuss here the etching of the as-developed photoresist pattern of lines and spaces. By examining time partition studies of the etching process, we show that the evolution of a photoresist profile has several distinct phases. These are caused by the material properties of the as-developed photoresist polymer, the change in these material properties due to the plasma interaction with the photoresist and to geometric effects caused by the interaction of faceting profiles and finite line widths. By exploiting sheath bending to direct ions into the sidewall of the lines we examine the etch characteristics of the photoresist side walls. Further by comparing wide to narrow lines, and nested to iso lines, we deconvolve the effects of line geometry and the material properties of the photoresist. For these studies pure argon and mixed argon/fluorocarbon chemistries are used.

  14. Azido--meconine-high ortho'Novolak resin-based negative ...

    Indian Academy of Sciences (India)

    A new photoactive compound (PAC), azido--meconine absorbing in the deep UV region has been blended with `alternating' and `semi-alternating' and `high ortho' alternating novolak resins, based on /-cresol. The new photoresists have been evaluated as a negative tone deep UV photoresist for mircolithography.

  15. Nanoparticle Photoresists: Ligand Exchange as a New, Sensitive EUV Patterning Mechanism

    KAUST Repository

    Kryask, Marie


    Hybrid nanoparticle photoresists and their patterning using DUV, EUV, 193 nm lithography and e-beam lithography has been investigated and reported earlier. The nanoparticles have demonstrated very high EUV sensitivity and significant etch resistance compared to other standard photoresists. The current study aims at investigating and establishing the underlying mechanism for dual tone patterning of these nanoparticle photoresist systems. Infrared spectroscopy and UV absorbance studies supported by mass loss and dissolution studies support the current model. © 2013SPST.

  16. Novel fabrication process for 3D meander-shaped microcoils in SU-8 dielectric and their application to linear micromotors (United States)

    Seidemann, Volker; Buettgenbach, Stephanus


    This paper reports on an optimized fabrication process for three dimensional coil structures such as meander or helical coils wound around in plane magnetic structures. The process consists of UV depth lithography employing AZ4562 and SU8 photo resists and electroplating of copper and nickel-iron. Furthermore SU8 is used as the embedding dielectric due to its excellent planarization properties and high structural aspect ratio. Special emphasis was laid on the decrease of via interconnect resistance by electroplating the vias and upper conductors in a single step thus avoiding a large number of resistive interfaces. This was achieved by sacrificial wiring and structured seed layers. The developed technology is applied to a variable reluctance micro motor with a novel design that avoids high friction. The presented concept makes use of a stator traveler configuration generating complementary attraction forces. The technology and design concept is presented and first results are demonstrated.

  17. Fabrication of three-dimensional SU-8 microchannels by proton beam writing for microfluidics applications: Fluid flow characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Shehri, S., E-mail:; Palitsin, V.; Webb, R.P.; Grime, G.W.


    The proton beam writing (PBW) technique was used to fabricate microfluidic structures in SU-8 resist. A network of the buried channels was fabricated as part of a project to develop functional microfluidic device for neuronal studies and self-powered microfluidics. Protons with energies between 2.5 MeV and 0.75 MeV were used to fabricate the buried channels with a minimum feature size of around 1 μm and depths of 40–55 μm. Roughness of channels sidewalls was around 2.5 nm rms. Exposure regime and examples of functional networks fabricated using PBW are described. COMSOL Multiphysics® software was used to model the flow characteristics of fluid in the SU-8 microchannels structured by PBW. The results obtained using PBW are compared with the structures fabricated by UV-lithography.

  18. Pyrolyzed Photoresist Electrodes for Integration in Microfluidic Chips for Transmitter Detection from Biological Cells

    DEFF Research Database (Denmark)

    Larsen, Simon Tylsgaard; Argyraki, Aikaterini; Amato, Letizia


    In this study, we show how pyrolyzed photoresist carbon electrodes can be used for amperometric detection of potassium-induced transmitter release from large groups of neuronal PC 12 cells. This opens the way for the use of carbon film electrodes in microfabricated devices for neurochemical drug...... screening applications. We also investigated the effect of using two different photoresists for fabrication of pyrolyzed photoresist electrodes. We observed a significant difference in the cross-sectional profile of band electrodes made of AZ 4562 and AZ 5214 photoresist. This difference can be explained...

  19. Simplified air bridge technique using photoresist UV stabilization process (United States)

    Tajadod, James; Insalaco, Linda J.


    Due to their favorable structural and electrical properties, air bridges are used extensively by silicon and GaAs monolithic microwave integrated circuit (MMIC) designers. Fabrication of such structures using the conventional techniques is complex. In this paper novel construction of air bridge structures of up to 7.5 micrometers high using an ultra violet (UV) stabilized bi-layer photoresist process, evaporated metal scheme, and lift-off patterning procedure, is realized. Deep UV stabilization of positive photo resist is discussed. Removal of the hardened resist via organic photo resist stripper is addressed.

  20. Photolithography of thick photoresist coating in anisotropically etched V-grooves for electrically controlled liquid crystal photonic bandgap fiber devices

    DEFF Research Database (Denmark)

    Wei, Lei; Khomtchenko, Elena; Alkeskjold, Thomas Tanggaard


    Thick photoresist coating for electrode patterning in anisotropically etched v-grooves is investigated. The photoresist coverage is compared with and without soft baking. Two-step exposure is applied for a complete exposure and minimizing the resolution loss....

  1. Chemical metallization of KMPR photoresist polymer in aqueous solutions (United States)

    Zeb, Gul; Duong, Xuan Truong; Vu, Ngoc Pi; Phan, Quang The; Nguyen, Duc Tuong; Ly, Viet Anh; Salimy, Siamak; Le, Xuan Tuan


    While conventional methods for preparing thin films of metals and metallic alloys on insulating substrates in the field of microelectromechanical systems (MEMS) include vapor deposition techniques, we demonstrate here that electroless deposition can be considered as an alternate efficient approach to metallize the surface of insulating substrates, such as KMPR epoxy photoresist polymer. In comparison with the physical and chemical vapor deposition methods, which are well-established for metallization of photoresist polymers, our electroless nickel plating requires only immersing the substrates into aqueous solutions in open air at low temperatures. Thin films of nickel alloy have been deposited electrolessly on KMPR surface, through a cost-effective and environmental chromium-free process, mediated through direct grafting of amine palladium complexes in aqueous medium. This covalent organic coating provides excellent adhesion between KMPR and the nickel film and allows better control of the palladium catalyst content. Covalent grafting and characterization of the deposited nickel film have been carried out by means of Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy techniques.

  2. Comparative study between the results of effective index based matrix method and characterization of fabricated SU-8 waveguide (United States)

    Samanta, Swagata; Dey, Pradip Kumar; Banerji, Pallab; Ganguly, Pranabendu


    A study regarding the validity of effective-index based matrix method (EIMM) for the fabricated SU-8 channel waveguides is reported. The design method is extremely fast compared to other existing numerical techniques, such as, BPM and FDTD. In EIMM, the effective index method was applied in depth direction of the waveguide and the resulted lateral index profile was analyzed by a transfer matrix method. By EIMM one can compute the guided mode propagation constants and mode profiles for each mode for any dimensions of the waveguides. The technique may also be used to design single mode waveguide. SU-8 waveguide fabrication was carried out by continuous-wave direct laser writing process at 375 nm wavelength. The measured propagation losses of these wire waveguides having air and PDMS as superstrates were 0.51 dB/mm and 0.3 dB/mm respectively. The number of guided modes, obtained theoretically as well as experimentally, for air-cladded waveguide was much more than that of PDMS-cladded waveguide. We were able to excite the isolated fundamental mode for the later by precise fiber positioning, and mode image was recorded. The mode profiles, mode indices, and refractive index profiles were extracted from this mode image of the fundamental mode which matched remarkably well with the theoretical predictions.

  3. Screen Printing of SU-8 Layers for Microstructure Fabrication / Ar Sietspiedi Uzklātu SU-8 Pārklājumi Mikro-Struktūru Izgatavošanai (United States)

    Klavins, J.; Mozolevskis, G.; Ozols A., A.; Nitiss, E.; Rutkis, M.


    We report on a screen printing fabrication process for large-area SU-8 layers utilised for the preparation of microstructures in display devices such as microelectronic, electrowetting or bistable devices. The screen printing method has been selected for its effectiveness and simplicity over traditionally used spin-coating ones. Layers and microstructures produced thereof have shown proper homogeneity. Relationships between screen parameters to coating thickness have been established. Coating on an ITO (indium tin oxide) hydrophobic surface is possible when surface has been treated by UV/Ozone to increase its aqueous ability. To this end, the hydrophilic microstructure grids have been successfully built on a hydrophobic layer by screen printing and traditional lithography processes. Compared to conventional spin-coating methods, the screen printing method offers the advantages of simple, cheap and fast fabrication, and is especially suitable for large-area display fabrication Rakstā aprakstīta sietspiedes metode liela izmēra SU-8 pārklājumu iegūšanai, lai izgatavotu mikrostruktūras mikroelektronikai, elektroslapināšanas un bistabilajiem ekrāniem. Sietspiede ir efektīvāka un vienkāršāka metode nekā tradicionāli izmantotā spin-coating metode. Šādiem pārklājumuiem un mikrostruktūrām ir pietiekoša homogenitāte. Tika atrasta sakarība starp sietu parametriem un pārklājumu biezumu. Pārklājumus var uzklāt uz hidrofobiskās ITO (indija alvas oksīds) virsmas, ja tā tiek apstrādāta ar UV/Ozonu, jo tas palielina ūdens slapināšanas īpašības. Tika izgatavoti hidrofīliskas mikrostruktūras režģi uz hidrofobiskas pamatnes ar sietspiedi un tradicionālo SU-8 litogrāfijas metodi. Salīdzinājumā ar tradicionālo spin-coating metodi, sietspiede ir vienkārša, lēta un ātra un ir labi piemērota liela izmēra ekrānu izgatavošanai.

  4. Characterization of Line Nanopatterns on Positive Photoresist Produced by Scanning Near-Field Optical Microscope

    Directory of Open Access Journals (Sweden)

    Sadegh Mehdi Aghaei


    Full Text Available Line nanopatterns are produced on the positive photoresist by scanning near-field optical microscope (SNOM. A laser diode with a wavelength of 450 nm and a power of 250 mW as the light source and an aluminum coated nanoprobe with a 70 nm aperture at the tip apex have been employed. A neutral density filter has been used to control the exposure power of the photoresist. It is found that the changes induced by light in the photoresist can be detected by in situ shear force microscopy (ShFM, before the development of the photoresist. Scanning electron microscope (SEM images of the developed photoresist have been used to optimize the scanning speed and the power required for exposure, in order to minimize the final line width. It is shown that nanometric lines with a minimum width of 33 nm can be achieved with a scanning speed of 75 µm/s and a laser power of 113 mW. It is also revealed that the overexposure of the photoresist by continuous wave laser generated heat can be prevented by means of proper photoresist selection. In addition, the effects of multiple exposures of nanopatterns on their width and depth are investigated.

  5. Photoresist latent and developer images as probed by neutron reflectivity methods. (United States)

    Prabhu, Vivek M; Kang, Shuhui; VanderHart, David L; Satija, Sushil K; Lin, Eric K; Wu, Wen-li


    Photoresist materials enable the fabrication of advanced integrated circuits with ever-decreasing feature sizes. As next-generation light sources are developed, using extreme ultraviolet light of wavelength 13.5 nm, these highly tuned formulations must meet strict image-fidelity criteria to maintain the expected performance gains from decreases in feature size. However, polymer photoresists appear to be reaching resolution limits and advancements in measurements of the in situ formed solid/solid and solid/liquid interface is necessary. This Review focuses on the chemical and physical structure of chemically amplified photoresists at the lithographic feature edge at length scales between 1 nm and 100 nm. Neutron reflectivity measurements provide insight into the nanometer-scale composition profiling of the chemical latent image at an ideal lithographic line-edge that separates optical resolution effects from materials processing effects. Four generations of advanced photoresist formulations were examined over the course of seven years to quantify photoresist/photoacid and photoresist/developer interactions on the fidelity of lithographic features. The outcome of these measurements complement traditional resist design criteria by providing the effects of the impacts of the photoresist and processing on the feature fidelity. These physical relations are also described in the context of novel resist architectures under consideration for next-generation photolithography with extreme-ultraviolet radiation. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Replication of optical microlens arrays using photoresist coated molds

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Dam-Hansen, Carsten; Stubager, Jørgen


    A cost reduced method of producing injection molding tools is reported and demonstrated for the fabrication of optical microlens arrays. A standard computer-numerical-control (CNC) milling machine was used to make a rough mold in steel. Surface treatment of the steel mold by spray coating...... with photoresist is used to smooth the mold surface providing good optical quality. The tool and process are demonstrated for the fabrication of an ø50 mm beam homogenizer for a color mixing LED light engine. The acceptance angle of the microlens array is optimized, in order to maximize the optical efficiency from...... the light engine. Polymer injection molded microlens arrays were produced from both the rough and coated molds and have been characterized for lenslet parameters, surface quality, light scattering, and acceptance angle. The surface roughness (Ra) is improved approximately by a factor of two after...

  7. UV radiometry issues for UV stabilization of photoresist (United States)

    Shi, Jianou; Grindle, Steven P.; Chen, Sharine; Owen, Greg; Insalaco, Linda J.; Cromer, Christopher L.; Goldner, Laurie S.


    The use of intense, broadband, ultraviolet (UV) radiation in the stabilization of photoresist requires stable UV sources and sensors, as well as suitable calibration procedures. We have constructed and measured the stability of a new UV transfer source standard with a spectrum that is identical to that of a commercially available photostabilizer. This device is particularly useful in calibrating the broadband UV detectors that monitor photostabilizer irradiance. The irradiance of this new source in a narrow band around 310 nm is monitored and found to be stable to better than 1.5% over 12 days. Spectral measurements of the source are also presented. The stability of two other commercially available UV sources is investigated and the behavior of the broadband UV sensors is discussed.

  8. Photoresist removal process by hydrogen radicals generated by W catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Takata, M. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531 (Japan)], E-mail:; Ogushi, K.; Yuba, Y.; Akasaka, Y. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531 (Japan); Tomioka, K.; Soda, E.; Kobayashi, N. [Semiconductor Leading Edge Technologies Inc., 16-1 Onogawa Tsukuba, Ibaraki, 305-8569 (Japan)


    Hydrogen radical process for photoresist removal by use of hot W catalyst has been investigated for a possible application to advanced Cu/low-k dielectric interconnects in LSI. It is found that etching rates of resists depend critically on sample temperature (T{sub s}) and are higher than 1 {mu}m/min at the optimized condition. H radical irradiation effects on porous methylsilsesquioxane (p-MSQ) have been studied from measurements of k value and capacitance of the advanced interconnect test sample. No radical process is observed to induce the increase in k value of p-MSQ films. These results suggest that the hydrogen radical process for resist removal with W catalyst is promising for production of advanced interconnects.

  9. Photoresist Design for Elastomeric Light Tunable Photonic Devices

    Directory of Open Access Journals (Sweden)

    Sara Nocentini


    Full Text Available An increasing interest in tunable photonic structures is growing within the photonic community. The usage of Liquid Crystalline Elastomer (LCE structures in the micro-scale has been motivated by the potential to remotely control their properties. In order to design elastic photonic structures with a three-dimensional lithographic technique, an analysis of the different mixtures used in the micro-printing process is required. Previously reported LCE microstructures suffer damage and strong swelling as a limiting factor of resolution. In this article, we reported a detailed study on the writing process with four liquid crystalline photoresists, in which the percentage of crosslinker is gradually increased. The experiments reveal that exploiting the crosslinking degree is a possible means in which to obtain suspended lines with good resolution, quite good rigidity, and good elasticity, thereby preserving the possibility of deformation by light irradiation.

  10. Duty cycle estimate of photoresist gratings via monitoring TM/TE diffraction efficiency ratio during development. (United States)

    Shen, Biyao; Zeng, Lijiang; Li, Lifeng


    We present an in situ duty cycle control method that relies on monitoring the TM/TE diffraction efficiency ratio of the -1st transmitted order during photoresist development. Owing to the anisotropic structure of a binary grating, at an appropriately chosen angle of incidence, diffraction efficiencies in TE and TM polarizations vary with groove depth proportionately, while they vary with duty cycle differently. Thus, measuring the TM/TE diffraction efficiency ratio can help estimate the duty cycle during development while eliminating the effect of photoresist thickness uncertainty. We experimentally verified the feasibility of this idea by fabricating photoresist gratings with different photoresist thicknesses. The experimental results were in good agreement with theoretical predictions.

  11. Contact printed masks for 3D microfabrication in negative resists

    DEFF Research Database (Denmark)

    Häfliger, Daniel; Boisen, Anja


    We present a process based on contact printed shadow masks for three dimensional microfabrication of soft and sensitive overhanging membranes in SU-8. A metal mask is transferred onto unexposed SU-8 from an elastomer stamp made of polydimethylsiloxane. This mask is subsequently embedded into the ......We present a process based on contact printed shadow masks for three dimensional microfabrication of soft and sensitive overhanging membranes in SU-8. A metal mask is transferred onto unexposed SU-8 from an elastomer stamp made of polydimethylsiloxane. This mask is subsequently embedded...... into the negative resist to protect buried material from UV-exposure. Unlike direct evaporation-deposition of a mask onto the SU-8, printing avoids high stress and radiation, thus preventing resist wrinkling and prepolymerization. We demonstrate effective monolithic fabrication of soft, 4-μm thick and 100-μm long...

  12. How to design a good photoresist solvent package using solubility parameters and high-throughput research (United States)

    Tate, Michael P.; Cutler, Charlotte; Sakillaris, Mike; Kaufman, Michael; Estelle, Thomas; Mohler, Carol; Tucker, Chris; Thackeray, Jim


    Understanding fundamental properties of photoresists and how interactions between photoresist components affect performance targets are crucial to the continued success of photoresists. More specifically, polymer solubility is critical to the overall performance capability of the photoresist formulation. While several theories describe polymer solvent solubility, the most common industrially applied method is Hansen's solubility parameters. Hansen's method, based on regular solution theory, describes a solute's ability to dissolve in a solvent or solvent blend using four physical properties determined experimentally through regression of solubility data in many known solvents. The four physical parameters are dispersion, polarity, hydrogen bonding, and radius of interaction. Using these parameters a relative cohesive energy difference (RED), which describes a polymer's likelihood to dissolve in a given solvent blend, may be calculated. Leveraging a high throughput workflow to prepare and analyze the thousands of samples necessary to calculate the Hansen's solubility parameters from many different methacrylate-based polymers, we compare the physical descriptors to reveal a large range of polarities and hydrogen bonding. Further, we find that Hansen's model correctly predicts the soluble/insoluble state of 3-component solvent blends where the dispersion, polar, hydrogen-bonding, and radius of interaction values were determined through regression of experimental values. These modeling capabilities have allowed for optimization of the photoresist solubility from initial blending through application providing valuable insights into the nature of photoresist.

  13. Replication of optical microlens array using photoresist coated molds. (United States)

    Chakrabarti, M; Dam-Hansen, C; Stubager, J; Pedersen, T F; Pedersen, H C


    A cost reduced method of producing injection molding tools is reported and demonstrated for the fabrication of optical microlens arrays. A standard computer-numerical-control (CNC) milling machine was used to make a rough mold in steel. Surface treatment of the steel mold by spray coating with photoresist is used to smooth the mold surface providing good optical quality. The tool and process are demonstrated for the fabrication of an ø50 mm beam homogenizer for a color mixing LED light engine. The acceptance angle of the microlens array is optimized, in order to maximize the optical efficiency from the light engine. Polymer injection molded microlens arrays were produced from both the rough and coated molds and have been characterized for lenslet parameters, surface quality, light scattering, and acceptance angle. The surface roughness (Ra) is improved approximately by a factor of two after the coating process and the light scattering is reduced so that the molded microlens array can be used for the color mixing application. The measured accepted angle of the microlens array is 40° which is in agreement with simulations.

  14. Reduction of surface leakage current in InAs/GaSb strained layer long wavelength superlattice detectors using SU-8 passivation (United States)

    Kim, H. S.; Plis, E.; Gautam, N.; Myers, S.; Sharma, Y.; Dawson, L. R.; Krishna, S.


    We report on SU-8 passivation for reducing surface leakage current in type-II InAs/GaSb strained layer superlattice detectors (λ100% cut-off˜12 μm). The electrical behavior of SU-8 passivated and unpassivated devices was compared for devices with variable mesa sizes. Dark current was reduced by more than one order of magnitude for the small area (50 μm×50 μm) passivated diode at 77 K. The surface resistivity, the responsivity and specific detectivity were measured for SU-8 passivated devices and are equal to 204 Ω cm, 0.58 A/W and 3.49×109 Jones, respectively (77 K).

  15. Performance improvement of InAs/GaSb strained layer superlattice detectors by reducing surface leakage currents with SU-8 passivation (United States)

    Kim, H. S.; Plis, E.; Khoshakhlagh, A.; Myers, S.; Gautam, N.; Sharma, Y. D.; Dawson, L. R.; Krishna, S.; Lee, S. J.; Noh, S. K.


    We report on SU-8 passivation for performance improvement of type-II InAs/GaSb strained layer superlattice detectors (λcut-off˜4.6 μm). Optical and electrical behavior of SU-8 passivated and unpassivated devices was compared. The dark current density was improved by four orders of magnitude for passivated single diodes at 77 K. The zero bias responsivity and detectivity at 77 K was equal to 0.9 A/W and 3.5×1012 Jones for SU-8 passivated single pixel diodes. FPA size diodes (24×24 μm2) were also fabricated and they showed responsivity and detectivity of 1.3 A/W and 3.5×1012 Jones, respectively at 77 K.

  16. Design, numerical simulation and experimental investigation of an SU-8 microgripper based on the cascaded V-shaped electrothermal actuators (United States)

    Voicu, Rodica-Cristina


    This paper presents the numerical simulation results and the experimental investigations of a polymeric microgripper designed using the cascaded V-shaped electrothermal actuators. The microgripper was simulated using electro-thermo-mechanical finite element method (FEM) based on Coventorware 2014 software in order to check the performance of the gripper. As structural material of the microgripper, the SU-8 biocompatible polymer was used during the fabrication process. The metallic micro-heaters were encapsulated in the polymeric actuation structures of the microgrippers to reduce the undesirable out-of-plane displacement of the gripper tips, to reduce the mechanical stress and to improve the thermal efficiency. Experimental testing has been performed to determine the openings of the microgripper tips as function of electrical current. A displacement of the tips of more than 50 pm can be obtained at an electrical current of around 25-26 mA. Over 27-28 mA the heaters are still working but a softening and a damaging status in the polymer were observed.

  17. Photodefinable electro-optic polymer for high-speed modulators

    NARCIS (Netherlands)

    Balakrishnan, M.; Faccini, M.; Diemeer, Mart; Verboom, Willem; Driessen, A.; Reinhoudt, David; Leinse, Arne


    Direct waveguide definition of a negative photoresist (SU8) containing tricyanovinylidenediphenylaminobenzene (TCVDPA) as electro-optic (EO) chromophore, has been demonstrated for the first time. This was possible by utilising the chromophore low absorption window in the UV region allowing

  18. New single-layer positive photoresists for 193-nm photolithography (United States)

    Okoroanyanwu, Uzodinma; Shimokawa, Tsutomu; Byers, Jeff D.; Medeiros, David R.; Willson, C. Grant; Niu, Qingshang J.; Frechet, Jean M. J.; Allen, Robert D.


    New series of chemically amplified, single layer, positive tone photoresists for 193 nm lithography have been developed. These resists were formulated from a series of cycloaliphatic co- and terpolymers of 2-methyl propyl bicyclo(2.2.1)hept-2- ene-5-carboxylate (carbo-tert-butoxynorbornene), bicyclo(2.2.1)hept-2-ene carboxylic acid (norbornene carboxylic acid), 8-methyl-8-carboxy tetracyclo(4,4,0.12,5,17,10)dodec-3-ene (methyltetracyclododecene carboxylic acid), norbornenemethanol, and maleic anhydride, which were synthesized by free radical, vinyl addition and ring opening metathesis polymerization techniques. The polymers derived from ring opening metathesis polymerization have bee successfully hydrogenated to provide yet another member of this group of materials. The cycloaliphatic polymer backbones provide etch resistance, mechanical properties and stability to radiation. The lithographic function is provided by carefully tailored pendant groups, which include an acid functionality that is masked by protecting groups that undergo acid catalyzed thermolysis as well as polar groups that influence the adhesion, wetability and dissolution properties of the polymer. The polymers are soluble in common organic solvents and have glass transition temperatures ranging from less than 60 degrees Celsius to higher than 250 degrees Celsius depending on their specific structure and mode of polymerization. They are at least as transparent at 193 nm as the corresponding acrylics. Their dry etch resistance varies with the formulation, but the base polymers etch more slowly than novolac under conditions typically used to pattern polysilicon. Upon exposure and baking, the resists have demonstrated high sensitivities (9-25 mJ/cm2), and 0.16 micrometer features have bean resolved.

  19. Compact silicon-based optrode with integrated laser diode chips, SU-8 waveguides and platinum electrodes for optogenetic applications (United States)

    Schwaerzle, M.; Paul, O.; Ruther, P.


    We report on a compact optrode, i.e. a MEMS-based, invasive, bidirectional neural interface allowing to control neural activity using light while neural signals are recorded nearby. The optrode consists of a silicon (Si) base carrying two pairs of bare laser diodes (LDs) emitting at 650 nm and of two 8 mm-long, 250 µm-wide and down to 50 µm-thick shanks extending from the base. Each LD is efficiently coupled to one of four 15 or 20 µm-wide and 13 µm-high SU-8 waveguides (WGs) running in pairs along the shanks. In addition, each shank comprises four 20 µm-diameter platinum electrodes for neural recording near the WG end facets. After encapsulation of the LDs with a Si cover chip blocking stray light and protecting the LDs from the harsh environment to which the probe is destined, the compact base measures only 4  ×  4  ×  0.43 mm3. The time averaged radiant emittance at the WG end facet is 96.9 mW mm-2 for an LD current of 35 mA at a duty cycle of 5%. The absolute electrode impedance at 1 kHz is 1.54  ±  0.06 MΩ. Using infrared thermography, the temperature increase of the probe during LD operation was determined to be about 1 K under neuroscientifically relevant operating conditions.

  20. Enhanced Response Speed of ZnO Nanowire Photodetector by Coating with Photoresist

    Directory of Open Access Journals (Sweden)

    Xing Yang


    Full Text Available Spin-coating photoresist film on ZnO nanowire (NW was introduced into the fabrication procedure to improve photoresponse and recovery speed of a ZnO NW ultraviolet photoelectric detector. A ZnO NW was first assembled on prefabricated electrodes by dielectrophoresis. Then, photoresist was spin-coated on the nanowire. Finally, a metal layer was electrodeposited on the nanowire-electrode contacts. The response properties and I-V characteristics of ZnO NW photodetector were investigated by measuring the electrical current under different conditions. Measurement results demonstrated that the detector has an enhanced photoresponse and recovery speed after coating the nanowire with photoresist. The photoresponse and recovery characteristics of detectors with and without spin-coating were compared to demonstrate the effects of photoresist and the enhancement of response and recovery speed of the photodetector is ascribed to the reduced surface absorbed oxygen molecules and binding effect on the residual oxygen molecules after photoresist spin-coating. The results demonstrated that surface coating may be an effective and simple way to improve the response speed of the photoelectric device.

  1. Absolute vacuum ultraviolet flux in inductively coupled plasmas and chemical modifications of 193 nm photoresist (United States)

    Titus, M. J.; Nest, D.; Graves, D. B.


    Vacuum ultraviolet (VUV) photons in plasma processing systems are known to alter surface chemistry and may damage gate dielectrics and photoresist. We characterize absolute VUV fluxes to surfaces exposed in an inductively coupled argon plasma, 1-50 mTorr, 25-400 W, using a calibrated VUV spectrometer. We also demonstrate an alternative method to estimate VUV fluence in an inductively coupled plasma (ICP) reactor using a chemical dosimeter-type monitor. We illustrate the technique with argon ICP and xenon lamp exposure experiments, comparing direct VUV measurements with measured chemical changes in 193 nm photoresist-covered Si wafers following VUV exposure.

  2. Optimization of Thick Negative Photoresist for Fabrication of Interdigitated Capacitor Structures (United States)


    the PR chemical. After exposure, a postexposure bake step using a hot plate or oven heating is used to complete the chemical transformations ...interdigitated capacitor (IDC) structures by lift-off process for use in high-frequency electrical characterization measurements. Target feature resolution was...spin-coat application, a soft-bake step is required to evaporate solvents and harden the PR layer. This can be performed either by hot plate or oven

  3. A Simple and Reliable PDMS and SU-8 Irreversible Bonding Method and Its Application on a Microfluidic-MEA Device for Neuroscience Research

    Directory of Open Access Journals (Sweden)

    Yufei Ren


    Full Text Available Polydimethylsiloxane (PDMS and SU-8 are currently two very commonly used polymeric materials in the microfluidics field for biological applications. However; there is a pressing need to find a simple, reliable, irreversible bonding method between these two materials for their combined use in innovative integrated microsystems. In this paper, we attempt to investigate the aminosilane-mediated irreversible bonding method for PDMS and SU-8 with X-Ray Photoelectron Spectroscopy (XPS surface analysis and bonding strength tests. Additionally, the selected bonding method was applied in fabricating a microelectrode array (MEA device, including microfluidic features, which allows electrophysiological observations on compartmentalized neuronal cultures. As there is a growing trend towards microfluidic devices for neuroscience research, this type of integrated microdevice, which can observe functional alterations on compartmentalized neuronal culture, can potentially be used for neurodegenerative disease research and pharmaceutical development.

  4. A Highly Selective Photoresist Ashing Process for Silicon Nitride Films by Addition of Trifluoromethane (United States)

    Saito, Makoto; Eto, Hideo; Makino, Nobuaki; Omiya, Kayoko; Homma, Tetsuya; Nagatomo, Takao


    A highly selective photoresist ashing process was developed for the fabrication of thin-film transistor liquid-crystal displays (TFT-LCDs). This ashing process utilizes downflow plasma consisting of a carbon trifluoromethane/oxygen (CHF3/O2) gas mixture at a low temperature. The etching selectivity of photoresist films to silicon nitride (SiN) film increased when using the CHF3/O2 gas mixture plasma, as compared to that when using the carbon tetrafluoride/oxygen (CF4/O2) gas mixture plasma. At the CHF3 gas flow rate of 30 sccm, a high etching selectivity ratio of about 1080 for the photoresist films to the SiN films was achieved at room temperature. On the basis of surface analysis results for SiN films and plasma analysis results for the CHF3/O2 gas mixture, a mechanism for the high etching selectivity of the photoresist films was proposed. Reaction products that were formed on SiN films by the CHF3/O2 gas mixture plasma obstructed the etching of SiN films by fluorine (F) radicals, resulting in the high selectivity. It was found that the CHF3/O2 gas mixture plasma reacted with SiN, resulting in the formation of a protective reaction product that is considered to be an ammonium salt such as (NH4)2SiF6.

  5. Precise Cross-Sectional Measurement of Photoresist Shrinkage Caused by Electron Beam Irradiation (United States)

    Ohashi, Takeyoshi; Sekiguchi, Tomoko; Yamaguchi, Atsuko; Tanaka, Junichi; Kawada, Hiroki


    A mechanism of the photoresist shrinkage induced by electron-beam (EB) irradiation was studied in detail. A precise cross-sectional profile of a photoresist pattern is obtained by a scanning transmission electron microscope (STEM) after HfO2 atomic layer deposition on a sample. Photoresist lines and spaces formed on either of bottom anti-reflective coating (BARC) layer or spin-on-glass (SOG) layer were exposed to EB at a much higher dose than a practical dose (to accelerate shrinkage intentionally). The obtained STEM images of the patterns before and after EB irradiation showed that EB irradiation causes necking of the pattern profile as well as linewidth slimming. In addition, it was suggested that the BARC layer shrinkage results in the elastic deformation of the pattern profile, whereas the SOG layer does not shrink. Furthermore, EB irradiation only to the lines or spaces was performed. The EB irradiation to spaces caused sidewall shrinkage and necking of the pattern profile, although no electron was irradiated directly into the pattern. This result is considered to be due to the electrons scattered from the spaces to the pattern sidewall. Finally, a Monte Carlo simulation showed that the distribution of the deposited energy on the pattern surface corresponds to the change of the pattern shape. Consequently, our study clarifies the importance of the effect of elastic shape change and the impact of the electrons scattered from the underlying layer to the sidewall on photoresist shrinkage.

  6. An improved method for characterizing photoresist lithographic and defectivity performance for sub-20nm node lithography (United States)

    Amblard, Gilles; Purdy, Sara; Cooper, Ryan; Hockaday, Marjory


    The overall quality and processing capability of lithographic materials are critical for ensuring high device yield and performance at sub-20nm technology nodes in a high volume manufacturing environment. Insufficient process margin and high line width roughness (LWR) cause poor manufacturing control, while high defectivity causes product failures. In this paper, we focus on the most critical layer of a sub-20nm technology node LSI device, and present an improved method for characterizing both lithographic and post-patterning defectivity performance of state-of-the-art immersion photoresists. Multiple formulations from different suppliers were used and compared. Photoresists were tested under various process conditions, and multiple lithographic metrics were investigated (depth of focus, exposure dose latitude, line width roughness, etc.). Results were analyzed and combined using an innovative approach based on advanced software, providing clearer results than previously available. This increased detail enables more accurate performance comparisons among the different photoresists. Post-patterning defectivity was also quantified, with defects reviewed and classified using state-of-the-art inspection tools. Correlations were established between the lithographic and post-patterning defectivity performances for each material, and overall ranking was established among the photoresists, enabling the selection of the best performer for implementation in a high volume manufacturing environment.

  7. Solubility studies of inorganic–organic hybrid nanoparticle photoresists with different surface functional groups

    KAUST Repository

    Li, Li


    © 2016 The Royal Society of Chemistry. The solubility behavior of Hf and Zr based hybrid nanoparticles with different surface ligands in different concentrations of photoacid generator as potential EUV photoresists was investigated in detail. The nanoparticles regardless of core or ligand chemistry have a hydrodynamic diameter of 2-3 nm and a very narrow size distribution in organic solvents. The Hansen solubility parameters for nanoparticles functionalized with IBA and 2MBA have the highest contribution from the dispersion interaction than those with tDMA and MAA, which show more polar character. The nanoparticles functionalized with unsaturated surface ligands showed more apparent solubility changes after exposure to DUV than those with saturated ones. The solubility differences after exposure are more pronounced for films containing a higher amount of photoacid generator. The work reported here provides material selection criteria and processing strategies for the design of high performance EUV photoresists.

  8. New approaches to production-worthy 193-nm photoresists based on acrylic copolymers (United States)

    Wallow, Thomas I.; Allen, Robert D.; Opitz, Juliann; Di Pietro, Richard A.; Brock, Phillip J.; Sooriyakumaran, Ratnam; Hofer, Donald C.


    We describe a series of improvements to the `v2' etch- resistant methacrylate 193 nm photoresist platform. `V2' itself possesses many desirable characteristics, but requires weak developers and lacks ultimate etch resistance for production processes. Modifications to address these challenges include incorporation of polar modifier monomers which provide improved developer compatibility, and use of alternative etch-resistant monomers which ameliorate the excessive hydrophobicity of isobornyl methacrylate. Specifically, we explore the use of methacrylonitrile as a polar modifier which simultaneously imparts strong-developer compatibility and improves RIE performance. Integration of these improvements results in methacrylate resists displaying strong-developer compatibility, sub-0.15 micrometers resolution, and etch rates equivalent to current 248 nm photoresists in prototype materials.

  9. Optical characterization of photopolymer and photoresist materials for storage, sensing, and security applications (United States)

    Feid, Timo; Frohmann, Sven; Rass, Jens; Müller, Christian; Orlic, Susanna


    Diffractive optical elements with application specific tailored properties can be fabricated by light induced alternation of the material's refractive index. Holographic polymers or photoresists are typically used for permanent optical structurization. Today, photostructurable media become core elements of photonic systems with innovative capabilities. We investigate different classes of organic photosensitive materials in order to optimize the interaction between the material and an optoelectronic system around. Some exemplary applications are microholographic data storage, 3D nano/micro structurization, optical patterning for advanced security features. Key issues include dynamic material response, spectral and temporal grating development, influence of the light intensity distribution, effects of pre-exposure and post-curing, etc. Materials under investigation are cationic and free radical polymerization systems, liquid crystalline polymer nanocomposites, and photoresist systems.

  10. Novel photoresist thin films with in-situ photoacid generator by molecular layer deposition (United States)

    Zhou, Han; Bent, Stacey F.


    Current photoresist materials are facing many challenges introduced by advanced lithographies, particularly the need for excellent compositional homogeneity and ultrathin film thickness. Traditional spin-on polymeric resists have inherent limitations in achieving a high level of control over the chemical composition, leading to interest in development of alternative methods for making photoresists. In this work, we demonstrate that molecular layer deposition (MLD) is a potential method for synthesizing photoresists because it allows for precise control over organic film thickness and composition. MLD utilizes sequential, self-limiting reactions of organic precursors to build a thin film directly on a substrate surface and grows organic films by depositing only one molecular layer at each precursor dose, which in turn allows for fine-tuning of the position and concentration of various functionalities in the deposited film. In this study, we use bifunctional precursors, diamine and diisocyanate, to build polyurea resist films via urea coupling reaction between the amine and isocyanate groups. Acid-labile groups and photoacid generators (PAGs) are embedded in the backbone of the resist films with a highly uniform distribution. The resist films were successfully deposited and characterized for both materials properties and resist response. E-beam patterning was achieved with the resist films. Cross-linking behavior of the resist films was observed, likely due to the aromatic rings in the films, which is undesirable for application as a positive-tone photoresist. Moreover, the in-situ polymer-bound PAGs had low sensitivity. It is suggested that this effect may arise because the PAG is cation-bound, leading to lower efficiency of sulfur-carbon bond cleavage in the sulfonium cation, which is needed to produce the photoacid, and consequently a lower photoacid yield. Further work is needed to improve the performance of the MLD resist films.

  11. Patterning with metal-oxide EUV photoresist: patterning capability, resist smoothing, trimming, and selective stripping (United States)

    Mao, Ming; Lazzarino, Frederic; De Schepper, Peter; De Simone, Danilo; Piumi, Daniele; Luong, Vinh; Yamashita, Fumiko; Kocsis, Michael; Kumar, Kaushik


    Inpria metal-oxide photoresist (PR) serves as a thin spin-on patternable hard mask for EUV lithography. Compared to traditional organic photoresists, the ultrathin metal-oxide photoresist ( 12nm after development) effectively mitigates pattern collapse. Because of the high etch resistance of the metal-oxide resist, this may open up significant scope for more aggressive etches, new chemistries, and novel integration schemes. We have previously shown that metal-oxide PR can be successfully used to pattern the block layer for the imec 7-nm technology node[1] and advantageously replace a multiple patterning approach, which significantly reduces the process complexity and effectively decreases the cost. We also demonstrated the formation of 16nm half pitch 1:1 line/space with EUV single print[2], which corresponds to a metal 2 layer for the imec 7-nm technology node. In this paper, we investigate the feasibility of using Inpria's metal-oxide PR for 16nm line/space patterning. In meanwhile, we also explore the different etch process for LWR smoothing, resist trimming and resist stripping.

  12. Coleman-Weinberg symmetry breaking in SU(8) induced by a third rank antisymmetric tensor scalar field II: the fermion spectrum (United States)

    Adler, Stephen L.


    We continue our study of Coleman-Weinberg symmetry breaking induced by a third rank antisymmetric tensor scalar, in the context of the SU(8) model (Adler 2014 Int. J. Mod. Phys. A 29 1450130) we proposed earlier. We focus in this paper on qualitative features that will determine whether the model can make contact with the observed particle spectrum. We discuss the mechanism for giving the spin \\frac{3}{2} field a mass by the BEH mechanism, and analyze the remaining massless spin \\frac{1}{2} fermions, the global chiral symmetries, and the running couplings after symmetry breaking. We note that the smallest gluon mass matrix eigenvalue has an eigenvector suggestive of U(1) B-L , and conjecture that the theory runs to an infrared fixed point at which there is a massless gluon with 3 to  -1 ratios in generator components. Assuming this, we discuss a mechanism for making contact with the standard model, based on a conjectured asymmetric breaking of Sp(4) to SU(2) subgroups, one of which is the electroweak SU(2), and the other of which is a ‘technicolor’ group that binds the original SU(8) model fermions, which play the role of ‘preons’, into composites. Quarks can emerge as 5 preon composites and leptons as 3 preon composites, with consequent stability of the proton against decay to a single lepton plus a meson. A composite Higgs boson can emerge as a two preon composite. Since anomaly matching for the relevant conserved global symmetry current is not obeyed by three fermion families, emergence of three composite families requires formation of a Goldstone boson with quantum numbers matching this current, which can be a light dark matter candidate.

  13. Physical properties of an oxide photoresist film for submicron pattern lithography

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Donyau [Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, 30076, Taiwan (China); Chang, Chun-Ming [Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, 30076, Taiwan (China); Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, 10617, Taiwan (China); Chen, Shi-Wei [Nano Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan (China); Yang, Chin-Tien [Nanotechnology Research Center, Industrial Technology Research Institute, Hsinchu, 31040, Taiwan (China); Hsueh, Wen-Jeng [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, 10617, Taiwan (China)


    The minimum etched pits of 300 nm diameter and the trenches of 300 nm width with a 50 nm depth for both geometries are prepared in the GeSbSn oxide photoresist on the silicon substrates. The lithographic patterns are recorded by direct laser writing, using a 405 nm laser diode and 0.9 numerical aperture media disc mastering system. The developed pit diameters in an inorganic oxide photoresist are smaller than the exposed laser beam spot diameter due to thermal lithography. The crystal structures of the as-sputtered and the annealed powder samples scraped from the sputtered films are examined by X-ray diffractometer. The effect of the heating rate on the crystallization temperatures is evaluated by a differential scanning calorimeter and the crystallization activation energy is determined from Kissinger's plot. The optical and absorption characteristics of the oxides are strongly dependent on the oxygen flow rate during the reactive magnetron sputtering process. The transmittance of the deposited films increases and the absorption decreases with increasing oxygen flow rate, which implies that at high oxygen flow rate, the film resembles dielectric material. The oxygen flow rate during the deposition process is defined within a limited range to obtain the proper extinction coefficient. The working extinction coefficients of the films ranging from 0.5 to 0.8 are applied in this study to achieve the sharp and vertical edge of the etched pits and trenches of 50 nm depth. - Highlights: • A photoresist layer consisting GeSbSnO with submicron patterning for optical device applications. • The thermal, optical properties and crystallization behaviors are reported. • A better working extinction coefficient ranges are decided experimentally. • The ranges define minimum size of the etched marks with smooth boundary. • Thermal lithography concept is introduced to explain experimental results.

  14. The importance of inner-shell electronic structure for enhancing the EUV absorption of photoresist materials. (United States)

    Closser, Kristina D; Ogletree, D Frank; Naulleau, Patrick; Prendergast, David


    In order to increase computation power and efficiency, the semiconductor industry continually strives to reduce the size of features written using lithographic techniques. The planned switch to a shorter wavelength extreme ultraviolet (EUV) source presents a challenge for the associated photoresists, which in their current manifestation show much poorer photoabsorption cross sections for the same dose. Here we consider the critical role that an inner-shell electronic structure might play in enhancing photoabsorption cross sections, which one can control by the choice of substituent elements in the photoresist. In order to increase the EUV sensitivity of current photoresists, it is critical to consider the inner-shell atomic structure of the elements that compose the materials. We validate this hypothesis using a series of halogenated organic molecules, which all have similar valence structures, but differ in the character of their semi-core and deep valence levels. Using various implementations of time-dependent density functional theory, the absorption cross sections are computed for the model systems of CH3X, X = H, OH, F, Cl, Br, I, as well as a representative polymer fragment: 2-methyl-phenol and its halogenated analogues. Iodine has a particularly high cross section in the EUV range, which is due to delayed absorption by its 4d electrons. The computational results are compared to standard database values and experimental data when available. Generally we find that the states that dominate the EUV oscillator strength are generated by excitations of deep valence or semi-core electrons, which are primarily atomic-like and relatively insensitive to the specific molecular structure.

  15. Study of the roughness in a photoresist masked, isotropic, SF6-based ICP silicon etch

    DEFF Research Database (Denmark)

    Larsen, Kristian Pontoppidan; Petersen, Dirch Hjorth; Hansen, Ole


    = 40 - 70 mTorr. Here the normalized roughness is the ratio of the roughness amplitude to the etch depth. The rough etching processes showed characteristic high-aspect-ratio and crystal-orientation-dependent surface morphology. The temporal evolution of this roughness was studied, and observations...... suggest a gradual buildup of surface contamination (redeposits) originating from the photoresist mask. A model was used to analyze the etched profiles with respect the internal etching conditions. The almost isotropic etching profiles, obtained in both rough and smooth etching processes, are generally...

  16. Measurement of viscoelasticity of UV photoresist used for nanoimprint lithography under confinement in nanometer-sized gaps (United States)

    Itoh, Shintaro; Takahashi, Kazuhiro; Fukuzawa, Kenji; Zhang, Hedong


    In UV nanoimprint lithography, the viscoelasticity of a photoresist is a dominant factor that affects defect control, throughput, and alignment accuracy, all of which are important for high-volume manufacturing. During the nanoimprint process, the photoresist is confined in nanogaps and nanocavities, between the mold and the substrate. In this study, we measure the viscoelasticity of a UV photoresist, PAK-01, confined in nanometer-sized gap widths by the sensitive shear force measurement method developed in our previous study. Experimental results show that PAK-01, a viscous liquid in the bulk state, turns into a viscoelastic liquid in the nanogaps. Qualitatively, a similar transition is observed with the typical acrylate monomer, isobornyl acrylate. These findings are significant factors that should be considered in the improvement of the accuracy and efficiency of nanoimprint lithography.

  17. Characterization and modeling of the metal diffusion from deep ultraviolet photoresist and silicon-based substrate. (United States)

    Wang, T K; Wan, M Y; Ko, F H; Tseng, C L


    The radioactive tracer technique was applied to investigate the out-diffusion of the transition metals (Cu, Fe and Co) from deep ultraviolet (DUV) photoresist into underlying substrate. Two important process parameters, viz., baking temperatures and substrate types (i.e., bare silicon, polysilicon, silicon oxide and silicon nitride), were evaluated. Results indicate that the out-diffusion of Co is insignificant, irrespective of the substrate type and baking temperature. The out-diffusion of Cu is significant for substrates of bare silicon and polysilicon but not for silicon oxide and nitride; for Fe, the story is reversed. The substrate type appears to strongly affect the diffusion, while the baking temperature does not. Also, the effect of solvent evaporation was found to play an important role in impurity diffusion. Using the method of numerical analysis, a diffusion profile was depicted in this work to describe the out-diffusion of metallic impurities from photoresist layer under various baking conditions. In addition, the effectiveness of various wet-cleaning recipes in removing metallic impurities such as Cu, Fe and Co was also studied using the radioactive tracer technique. Among the six cleaning solutions studied, SC2 and SPM are the most effective in impurity removal. An out-diffusion cleaning model was first proposed to describe the cleaning process. A new cleaning coefficient, h(T), was suggested to explain the cleaning effect. The cleaning model could explain the tracer results.

  18. A Positive Photoresist Optimized For Both I-Line And UV-3 Exposure (United States)

    Grunwald, John T.; Cordes, William F.; San Giacomo, Keith D.; Ben-Bassat, Joseph; Shalom, Eitan; Ben-Shushan, Giora


    Data is presented on a positive photoresist designated as PR-1024 Megabit (MB), whose chemistry includes a cresol novolak, coupled with 2-1-4 diazonapthoquinone chloride. The type and M.W. of the coupled novolak were found to be of prime importance. UV absorption of the photoactive compound in the resist is in the range of 230 to 380 nm, with prominent peaks at 230, 270 and 370nm. Extensive SEM data is presented showing geometries obtained on the Micralign 600-552HT in the UV-3 mode. Micron capabilities are demonstrated with edge wall profiles of approximately 85°. A salient feature of the resist is its availability both in the ECA solvent mode (PR-1024MB) as well as "safe solvent" variety (EPA-1024MB). Exposure energies in the UV-3 mode were studied, ranging from 170 to 270 mJ/cm2. Linewidth control of both isolated/group lines is reported at various exposure energies, indicating wide process latitude. Used as an I-Line photoresist, sub-micron capabilities (0.5 micron) were demonstrated with edge acuities in the 80°-85° range. Wide process latitude is demonstrated with both types of exposure tools. Using I-Line steppeis and projection aligners, exposure energies were varied up to and including the 270 mJ/cm2 region. Dry processing (plasma etching) data will also be displayed.

  19. Correlation of experimentally measured atomic scale properties of EUV photoresist to modeling performance: an exploration (United States)

    Kandel, Yudhishthir; Chandonait, Jonathan; Melvin, Lawrence S.; Marokkey, Sajan; Yan, Qiliang; Grzeskowiak, Steven; Painter, Benjamin; Denbeaux, Gregory


    Extreme ultraviolet (EUV) lithography at 13.5 nm stands at the crossroads of next generation patterning technology for high volume manufacturing of integrated circuits. Photo resist models that form the part of overall pattern transform model for lithography play a vital role in supporting this effort. The physics and chemistry of these resists must be understood to enable the construction of accurate models for EUV Optical Proximity Correction (OPC). In this study, we explore the possibility of improving EUV photo-resist models by directly correlating the parameters obtained from experimentally measured atomic scale physical properties; namely, the effect of interaction of EUV photons with photo acid generators in standard chemically amplified EUV photoresist, and associated electron energy loss events. Atomic scale physical properties will be inferred from the measurements carried out in Electron Resist Interaction Chamber (ERIC). This study will use measured physical parameters to establish a relationship with lithographically important properties, such as line edge roughness and CD variation. The data gathered from these measurements is used to construct OPC models of the resist.

  20. Comparison of High Resolution Negative Electron Beam Resists

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Schøler, Mikkel; Shi, Peixiong


    Four high resolution negative electron beam resists are compared: TEBN-1 from Tokuyama Corp. Japan, ma-N 2401XP and mr-L 6000AXP from microresist technology GmbH Germany, and SU-8 2000 series from MicroChem Corp., USA. Narrow linewidth high density patterns are defined by 100 kV electron beam...

  1. Oxide Nanoparticle EUV (ONE) Photoresists: Current Understanding of the Unusual Patterning Mechanism

    KAUST Repository

    Jiang, Jing


    © 2015 SPST. In the past few years, industry has made significant progress to deliver a stable high power EUV scanner and a 100 W light source is now being tested on the manufacuring scale. The success of a high power EUV source demands a fast and high resolution EUV resist. However, chemcially amplied resists encounter unprecedented challenges beyond the 22 nm node due to resolution, roughness and sensitivity tradeoffs. Unless novel solutions for EUV resists are proposed and further optimzed, breakthroughs can hardly be achieved. Oxide nanoparticle EUV (ONE) resists stablized by organic ligands were originally proposed by Ober et al. Recently this work attracts more and more attention due to its extraordinanry EUV sensitivity. This new class of photoresist utilizes ligand cleavage with a ligand exchange mechanism to switch its solubilty for dual-tone patterning. Therefore, ligand selection of the nanoparticles is extremely important to its EUV performance.

  2. Studying the Mechanism of Hybrid Nanoparticle Photoresists: Effect of Particle Size on Photopatterning

    KAUST Repository

    Li, Li


    © 2015 American Chemical Society. Hf-based hybrid photoresist materials with three different organic ligands were prepared by a sol-gel-based method, and their patterning mechanism was investigated in detail. All hybrid nanoparticle resists are patternable using UV exposure. Their particle sizes show a dramatic increase from the initial 3-4 nm to submicron size after exposure, with no apparent inorganic content or thermal property change detected. XPS results showed that the mass percentage of the carboxylic group in the structure of nanoparticles decreased with increasing exposure duration. The particle coarsening sensitivities of those hybrid nanoparticles are consistent with their EUV performance. The current work provides an understanding for the development mechanism and future guidance for the design and processing of high performance resist materials for large-scale microelectronics device fabrication.

  3. Microwave-Assisted Syntheses in Recyclable Ionic Liquids: Photoresists Based on Renewable Resources. (United States)

    Petit, Charlotte; Luef, Klaus P; Edler, Matthias; Griesser, Thomas; Kremsner, Jennifer M; Stadler, Alexander; Grassl, Bruno; Reynaud, Stéphanie; Wiesbrock, Frank


    The copoly(2-oxazoline) pNonOx80 -stat-pDc(=) Ox20 can be synthesized from the cationic ring-opening copolymerization of 2-nonyl-2-oxazoline NonOx and 2-dec-9'-enyl-2-oxazoline Dc(=) Ox in the ionic liquid n-hexyl methylimidazolium tetrafluoroborate under microwave irradiation in 250 g/batch quantities. The polymer precipitates upon cooling, enabling easy recovery of the polymer and the ionic liquid. Both monomers can be obtained from fatty acids from renewable resources. pNonOx80 -stat-pDc(=) Ox20 can be used as polymer in a photoresist (resolution of 1 μm) based on UV-induced thiol-ene reactions. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  4. EUV photoresist performance results from the VNL and the EUV LLC (United States)

    Cobb, Jonathan L.; Dentinger, Paul M.; Hunter, Luke L.; O'Connell, Donna J.; Gallatin, Gregg M.; Hinsberg, William D.; Houle, Frances A.; Sanchez, Martha I.; Domke, Wolf-Dieter; Wurm, Stefan; Okoroanyanwu, Uzodinma; Lee, Sang Hun


    If EUV lithography is to be inserted at the 65-nm node of the 2001 International Technology Roadmap for Semiconductors, beta-tool resists must be ready in 2004. These resists should print 35-65 nm lines on a 130-nm pitch with LER below 4 nm 3s. For throughput considerations, the sizing dose should be below 4 mJ/cm2. The VNL and EUV LLC resist development program has measured the resolution, LER, and sizing dose of approximately 60 ESCAP photoresists with the 10X exposure tools at Sandia National Laboratories. The NA of these tools is 0.088, and every resist measured would support the beta-tool resolution requirement if the resolution scales with NA as predicted by optics. 50-nm dense lines have been printed with monopole off-axis illumination, but 35-nm resolution on a 130-nm pitch remains to be demonstrated. Only one photoresist met the LER specification, but its sizing dose of 22 mJ/cm2 is over five times too large. The power spectral density of the roughness of every resist has a Lorentzian line shape, and most of the roughness comes from frequencies within the resolution of the exposure tools. This suggests a strong contribution from mask and optics, but more work needs to be done to determine the source of the roughness. Many resists have sizing doses below the 4 mJ/cm2 target, and neither resolution nor LER degrades with decreasing sizing dose, suggesting that shot noise is not yet affecting the results. The best overall resist resolved 80-nm dense lines with 5.3 nm 3s LER on 100-nm dense lines at a sizing dose of 3.2 mJ/cm2. Thus, it comes close to, but does not quite meet, the beta-tool resist targets.

  5. Unraveling the role of secondary electrons upon their interaction with photoresist during EUV exposure (United States)

    Pollentier, Ivan; Vesters, Yannick; Jiang, Jing; Vanelderen, Pieter; de Simone, Danilo


    The interaction of 91.6eV EUV photons with photoresist is very different to that of optical lithography at DUV wavelength. The latter is understood quite well and it is known that photons interact with the resist in a molecular way through the photoacid generator (PAG) of the chemically amplified resist (CAR). In EUV however, the high energy photons interact with the matter on atomic scale, resulting in the generation of secondary electrons. It is believed that these secondary electrons in their turn are responsible in chemical modification and lead to switching reactions that enable resist local dissolution. However, details of the interaction are still unclear, e.g. which reaction an electron with a given energy can initiate. In this work we have introduced a method to measure the chemical interaction of the secondary electrons with the EUV resist. The method is based on electron gun exposures of low energy electrons (range 1eV to 80eV) in the photoresist. The chemical interaction is then measured by Residual Gas Analysis (RGA), which can analyze out of the outgassing which and how much reaction products are generated. In this way a `chemical yield' can be quantified as function of electron energy. This method has been successfully applied to understand the interaction of secondary electrons on the traditional CAR materials. The understanding was facilitated by testing different compositions of an advanced EUV CAR, where resp. polymer only, polymer+PAG, and polymer+PAG+quencher are tested with the electron gun. It was found that low energy electrons down to 3-4eV can activate PAG dissociation, which can lead to polymer deprotection. However it was observed too that energy electrons of 12eV and higher can do direct deprotection even in absence of the PAG. In addition, testing suggests that electrons can generate also other chemical changes on the polymer chain that could lead to cross-linking.

  6. Reliability of contrast and dissolution-rate-derived parameters as predictors of photoresist performance (United States)

    Spragg, Peggy M.; Hurditch, Rodney J.; Toukhy, Medhat A.; Helbert, John N.; Malhotra, Sandeep


    The definition and use of contrast in photolithography has been adapted from the science and technology of photographic imaging media. Thus, a high contrast resists/process should allow useful high resolution images to be delineated even from a low contrast optical system (ie. one with low MTF) and hence provide improved resolution for diffracted limited imaging. Furthermore, it has been widely recognized and clearly documented, for example in ASTM F1059-87 that: 'The contrast value is a measure of process latitude of the photoresist'. Despite these assertions, there is a large body of evidence which suggests that contrast may not be a quantitative predictor of either resolution or process latitude, and in several cases opposite trends are reported. The authors of this paper set out to explore the utility of reliability of photoresist contrast (which we will refer to as 'gamma') as a predictor or resist performance including image profile, linearity and critical dimension control, both as a function of process variables such as film thickness, bake and develop conditions and as a function of resist composition. The influence of the precision of experimental measurements on the reliability of gamma determination is investigated. The recently reported variation of gamma with film thickness, which exhibits both a 'swing' and 'bulk' effect is confirmed. Experimental and computer simulation results show a 180 degree(s) out of phase relationship with Eo and an almost linear decrease in gamma (measured at Emax or Emin) with increase in film thickness, which is consistent with published theory. However, the phase relationship may be perturbed for conditions in which gamma is a strong function of process variables such as develop time and post exposure bake. It is shown that gamma correlates reasonably well with resist profile but less so with critical dimension, especially when comparing resists with varying optical absorption properties, or systems which exhibit high

  7. Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Gong, Lijun [Research and Development Department, Guangzhou Fastprint Circuit Tech Co., Ltd., Guangzhou 510663 (China); He, Wei, E-mail: [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research and Development Department, Guangdong Guanghua Sci-Tech Co., Ltd., Shantou 515000 (China)


    Highlights: • Air atmosphere plasmacould generatehydrophilic groups of photo-resistive film. • Better wettability of photo-resistive filmled tohigher plating uniformity of copper pillars. • New flow isreduced cost, simplified process and elevated productivity. - Abstract: The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O{sub 2}−CF{sub 4} low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of C−O, O−C=O, C=O and −NO{sub 2} by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

  8. Characteristic study of electron beam stabilization for deep-UV photoresists (United States)

    Kim, Myoung-Soo; Choi, Jae-Hak; Rho, Chi H.; Hong, Min-Jong; Jun, Bum-Jin; Gil, Myung-Goon; Kim, Bong-Ho; Ahn, Dong-Jun; Ross, Matthew F.; Wong, Selmer S.


    As the design rule of device shrinks below 0.14 micrometer, the higher resolution is required for real device application. With smaller feature size below 0.14 micrometer, the lower coating thickness of resist is essential because of the pattern collapse issue at the high aspect ratio. However, the lower resist thickness induces the problem of etch selectivity due to the limited etch resistance of resist. In this study, the method of electron beam stabilization has been applied for improving the etch selectivity of resist patterns having an aspect ratio less than 3:1. With applying the electron beam stabilization, the Deep-UV photoresists based on the chemical structures of Acetal (AS106) and Escap (UV82) types have been evaluated in the respect of etch selectivity as the functions of an electron beam dose and etch condition. The metal etch rate reductions of 20 percent and 26 percent have been occurred for the resists of Acetal and Escap type, respectively, at 2000 (mu) C/cm2. And the thermal and chemical properties were characterized before and after electron beam stabilization using DSC, TGA, and FT-IR. The cross-sectional views of resist pattern after electron beam processing were also investigated to know the chemical stability of resist during the electron beam process. Based on the experimental results, the application possibility of electron beam stabilization for real device fabrication below 0.14 micrometer has been presented in this paper.

  9. Comparing 193 nm photoresist roughening in an inductively coupled plasma system and vacuum beam system (United States)

    Titus, M. J.; Nest, D. G.; Chung, T.-Y.; Graves, D. B.


    We present a comparison of blanket 193 nm photoresist (PR) roughening and chemical modifications of samples processed in a well-characterized argon (Ar) inductively coupled plasma (ICP) system and an ultra-high vacuum beam system. In the ICP system, PR samples are irradiated with Ar vacuum ultraviolet (VUV) and Ar ions, while in the vacuum beam system, samples are irradiated with either a Xe-line VUV source or Ar-lamp VUV source with Ar ions. Sample temperature, photon flux, ion flux and ion energy are controlled and measured. The resulting chemical modifications to bulk 193 nm PR and surface roughness are analysed with Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy. We demonstrate that under VUV-only conditions in the vacuum beam and ICP (with no substrate bias applied) systems 193 nm PR does not roughen. However, roughness increases with simultaneous high energy (>70 eV) ion bombardment and VUV irradiation and is a function of VUV fluence, substrate temperature and photon-to-ion flux ratio. PR processed in the ICP system experiences increased etching, probably due to release of H- and O-containing gaseous products and subsequent chemical etching, in contrast to samples in the vacuum beam system where etch-products are rapidly pumped away. The surface roughness structure and behaviour, however, remain similar and this is attributed to the synergy between VUV-photon and positive ions.

  10. Modeling and simulation of low-energy electron scattering in organic and inorganic EUV photoresists (United States)

    Vaglio Pret, Alessandro; Graves, Trey; Blankenship, David; Biafore, John J.


    Alternative photoresist platforms are being developed with the goal of meeting Resolution, Roughness and Sensitivity requirements for EUV lithography. Metal-based materials appear promising due to the high etch resistance, high absorption, and high resolution. However, the exposure mechanism of these materials is quite different from that of organic chemically amplified resists. The current electron-scattering model built into PROLITHTM X6.0 allows a direct comparison of the exposure mechanisms for different resist platforms: in particular, it is now possible to estimate the intrinsic resist uncertainty by evaluating electron, acid shot noise and spatial blurring, while forcing the photon shot noise contribution to zero. A comparison between organic resists and metal-based platforms reveals how the denser nature of the latter help containing the electron scattering in a much closer radius around the absorption event. The consequent electron-reaction (acid generation for photo-active-generator-containing organic materials, ligand dissociation for the metal-oxides) reflects the electron shot noise of the different platforms. The higher absorption combined with lower blur of the metaloxide materials seem to become of crucial importance for the 5 nm technology node and beyond.

  11. Application of aziridine reactive rinses in a post-development process to reduce photoresist pattern collapse (United States)

    Yeh, Wei-Ming; Lawson, Richard A.; Tolbert, Laren M.; Henderson, Clifford L.


    One of the problems for lithographic processes at very small feature scales is pattern collapse caused by unbalanced capillary forces experienced by the photoresist patterns during the final deionized water rinse and drying process. The use of surfactants or super critical fluids to reduce collapse problems has been proposed and studied by many research groups. However, the patterns rinsed with low surface tension fluids appear in many cases to shrink or such treatments cause other feature deformations. Super critical fluid processing requires major changes to the ways in which current track systems operate and can result in swelling and deformation of the resist features as well. Instead of utilizing super critical fluids or adding surfactants to the rinse liquid, one general methodology we have pursued for alleviating such pattern collapse problems involves the actual strengthening of the resist feature itself during wet processing in the development and rinse cycle. One method we have investigated extensively is the use of post-development resist surface crosslinking reactions while the resist structures are still in their wet state, a process we term "reactive rinsing". Such reactive rinse processes have shown significant impact on improving resist pattern collapse. However, previous chemistries used for such reactive rinse processes have either: (1) been complex mixtures that potentially have long term stability problems (i.e. thus making their application in a fab environment more difficult) or (2) been specific to a certain resist types in that the chemistries react with only certain resist functional groups that may not be present in all resists of interest (e.g. some chemistries only work with phenolic resins such as those found in DUV or EUV resists). Therefore, the goal of this work has been to investigate other novel reactive rinse chemistries that are both more robust and which can function with different families of resist materials. Poly

  12. Experimental investigation of photoresist etching by kHz AC atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijun, E-mail:; Zheng, Yashuang; Wu, Chen; Jia, Shenli


    Graphical abstract: Pin-ring electrode, double-ring electrode and multi-electrode kHz AC atmospheric pressure plasma jet were used to etch PR on Si wafer, and a corresponding parametric study was carefully investigated. Display Omitted - Highlights: • The surface roughness increases dramatically after APPJ treatment. • The etch rate of the pin-ring electrode APPJ is the highest than that of the multi-electrode APPJ and the double-ring electrode APPJ. • Ar APPJ has a much higher etch rate and more irregular etch trace than He APPJ. • The effective etching initially increases and then decreases with the increment of plasma jet outlet to PR surface distance. - Abstract: In this study, the mechanism of the photoresist (PR) etching by means of a kHz AC atmospheric pressure plasma jet (APPJ) is investigated. The scanning electron (SEM) and the polarizing microscope are used to perform the surface analysis, and the mechanical profilometry is applied to diagnose the etch rate. The results show that granulated structure with numerous microparticles appears at the substrate surface after APPJ treatment, and the etch rate in the etch center is the fastest and gradually slows down to the edge of etch region. In addition, the pin-ring electrode APPJ has the highest etch rate at but easy to damage the Si wafer, the double-ring APPJ is the most stable but requires long time to achieve the ideal etch result, and the etch rate and the etch result of the multi-electrode APPJ fall in between. Ar APPJ had much higher PR etch rate and more irregular etch trace than He APPJ. It is speculated that Ar APPJ is more energetic and effective in transferring reactive species to the PR surface. It is also observed that the effective etch area initially increases and then decreases as plasma jet outlet to the PR surface distance increases.

  13. Development of High-speed and Environmentally Friendly Photoresist Removal Process using Pulsed Microwave Plasma in Water Vapor (United States)

    Ishijima, Tatsuo; Kitano, Takuya; Ito, Takuya; Suzuki, Hiroaki; Tanaka, Yasunori; Uesugi, Yoshihiko; Nishiyama, Takashi; Horibe, Hideo


    A novel photoresist removing technique using a pulsed microwave excited plasma produced in vaporized water bubble (MWBP) has remarkable properties such as environmentally-friendly and low temperature process. This photoresist removal method has been studied to apply a practical semiconductor manufacturing process. On the other hand, the minimal-fabrication system (minimal-fab) without using a clean room has been proposed and developed in order to adapt a high-variety low-volume semiconductor manufacturing process. Recently MOS device production has been succeeded using the minimal-fab. It is expected to evaluate the proposed MWBP ashing technology ability and clarify the possibility for a practical semiconductor manufacturing process to be incorporated in the minimal-fab. In order to apply MWBP for the minimal-fab, reduction of the input microwave power is necessary because the size of the minimal-fab is a compact and is highly standardized to maximize the convenience of the fabrication system utilization. In this study, we have investigated MWBP production methods to reduce the MWBP production power. We found that the decrease in the MWBP production power can be achieved by introducing a new bubble-control-structure to keep the bubble around the microwave antenna.

  14. The formation of photoresist film with thicknesses from 0.7 microns to 100 microns on surfaces with considerable relief by spray coating on the heated substrate (United States)

    Romashkin, Alexey V.; Levin, Denis D.; Rozanov, Roman Yu.; Nevolin, Vladimir K.


    The principle of the formation of thin and thick photoresist films on surfaces with considerable relief by the aerosol deposition using ultra low flow was investigated. It was shown that the change in the photoresist blend composition of solution is required with decreasing film thickness less than 1 micron to achieve a roughness of less than 150 nm. And the film at least 0.7 microns thickness can be formed and have the uniform film thickness as on the walls and on horizontal surfaces on the substrate with grooves obtained by etching liquid. It is shown that even with a film thickness of 10 microns vertical walls may be partially cover the of the photoresist and unfilled plasma-chemical etching grooves with vertical walls, whose width not exceeding 10 microns. To determine the uniformity of film thickness atomic force microscopy was used. And it was shown that up to 2 microns of film thickness spectroscopic methods with the analysis of the fluorescent signal intensity for positive photoresists is possible to use too.

  15. Parametric Study on the Physical Action of Steam-Water Mixture Jet: Removal of Photoresist Film from Silicon Wafer Surfaces (United States)

    Mashiko, Takashi; Sanada, Toshiyuki; Nishiyama, Itsuo; Horibe, Hideo


    We performed experiments to elucidate the physical action of a steam-water mixture jet, which we have proposed as a promising, environmentally friendly tool for cleaning surfaces. Photoresist-coated silicon wafers were adopted as the target and the jet performance of resist removal was evaluated, with several parameters being varied. We found that the resist-removal performance improves as the thickness or the mechanical strength of the resist film decreases, resist-wafer adhesivity decreases, or jet duration increases. The results imply that the essential part of the resist removal by the jet is a physical process including peel-off, in contrast to the established techniques such as the batch cleaning method utilizing chemical reactions. The results also indicate that the physical impact of the jet can be controlled, which will be a significant advantage in applying the jet as a cleaning technique.

  16. Synthesis of Narrow Molecular Weight Distribution Norbornene-Lactone Functionalized Polymers by Nitroxide-Mediated Polymerization: Candidates for 193-nm Photoresist Materials

    Directory of Open Access Journals (Sweden)

    Zi Jun Wang


    Full Text Available One hundred ninety three-nanometer candidate photoresist materials were synthesized by nitroxide-mediated polymerization (NMP. Statistical copolymerizations of 5-methacryloyloxy-2,6-norboranecarbolactone (NLAM with 5–10 mol% of controlling co-monomers (which are necessary for controlled polymerizations of methacrylates by NMP with the initiator used in the feed, such as styrene (ST, p-acetoxystyrene (AcOST, 2-vinyl naphthalene (VN and pentafluorostyrene (PFS, using the unimolecular BlocBuilder® initiator in 35 wt% dioxane solution at 90 °C were performed. As little as 5 mol% controlling comonomer in the feed was demonstrated to be sufficient to lead to linear evolution of number average molecular weight  with respect to conversion up to 50%, and the resulting copolymers had dispersities  of ~1.3 in most cases, an attractive feature for reducing line width roughness (LWR in photoresists. The copolymers generally showed relatively low absorbance at 193 nm, comparable to other 193-nm candidate photoresists reported previously, despite the inclusion of a small amount of the styrenic co-monomers in the copolymer.

  17. A comparison of chilled DI water/ozone and CO{sub 2}-based supercritical fluids as replacements for photoresist-stripping solvents

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Davenhall, L.B.; Barton, J.; Taylor, C.M.V. [Los Alamos National Lab., NM (United States). Chemical Science and Technology Div.; Tiefert, K. [Hewlett-Packard Co., Santa Clara, CA (United States)


    Part of the Hewlett Packard Components Group`s Product Stewardship program is the ongoing effort to investigate ways to eliminate or reduce as much as possible the use of chemical substances from manufacturing processes. Currently used techniques to remove hard-baked photoresists from semiconductor wafers require the use of inorganic chemicals or organic strippers and associated organic solvents. Environmental, health and safety, as well as cost considerations prompted the search for alternative, more environmentally-benign, and cost-effective solutions. Two promising, emerging technologies were selected for evaluation: the chilled DI water/ozone technique and supercritical fluids based on carbon dioxide (CO{sub 2}). Evaluating chilled DI water/ozone shows this process to be effective for positive photoresist removal, but may not be compatible with all metallization systems. Testing of a closed-loop CO{sub 2}-based supercritical CO{sub 2} Resist Remover, or SCORR, at Los Alamos, on behalf of Hewlett-packard, shows that this treatment process is effective in removing photoresists, and is fully compatible with commonly used metallization systems. In this paper, the authors present details on the testing programs conducted with both the chilled DI H{sub 2}O/ozone and SCORR treatment processes.

  18. Low-cost and high-resolution x-ray lithography utilizing a lift-off sputtered lead film mask on a Mylar substrate (United States)

    Wisitsoraat, A.; Mongpraneet, S.; Phatthanakun, R.; Chomnawang, N.; Phokharatkul, D.; Patthanasettakul, V.; Tuantranont, A.


    In this work, a low-cost and high-resolution x-ray micromask is developed by sputtered lead film on a Mylar sheet substrate with the lift-off process and the x-ray mask is experimented for patterning SU-8 negative photoresist on a glass substrate. Sputtering is selected for Pb thick film deposition due to its high sputtering yield. The Pb mask is used for x-ray lithography of SU-8 photoresist with 5 µm closely spaced square array patterns, designed for electrowetting electrodes on a microfluidic chip. For 140 µm thick SU-8 photoresist, a Pb film thickness of around 10 µm was used to block x-rays with 95% x-ray image contrast at a critical dose of 4200 mJ cm-3. A high aspect ratio of 26.5 of SU8 microstructure with 5 µm lateral resolution has been demonstrated by the developed low-cost Pb-based x-ray mask. In addition, a steep sidewall angle of nearly 90° for SU-8 structure is confirmed. The results demonstrate that the Pb-based x-ray mask offers high-resolution x-ray lithography at a very low cost. Therefore, it is highly promising for commercial applications.

  19. Electrochemical micromachining of micro-dimple arrays on cylindrical inner surfaces using a dry-film photoresist

    Directory of Open Access Journals (Sweden)

    Qu Ningsong


    Full Text Available The application of surface textures has been employed to improve the tribological performance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-dimple arrays, but the fabrication of such arrays on cylindrical inner surfaces remains a challenge. In this study, a dry-film photoresist is used as a mask during through-mask electrochemical micromachining to successfully prepare micro-dimple arrays with dimples 94 μm in diameter and 22.7 μm deep on cylindrical inner surfaces, with a machining time of 9 s and an applied voltage of 8 V. The versatility of this method is demonstrated, as are its potential low cost and high efficiency. It is also shown that for a fixed dimple depth, a smaller dimple diameter can be obtained using a combination of lower current density and longer machining time in a passivating sodium nitrate electrolyte.

  20. Supercritical CO2 drying of poly(methyl methacrylate) photoresist for deep x-ray lithography: a brief note (United States)

    Shukla, Rahul; Abhinandan, Lala; Sharma, Shivdutt


    Poly(methyl methacrylate) (PMMA) is an extensively used positive photoresist for deep x-ray lithography. The post-development release of the microstructures of PMMA becomes very critical for high aspect ratio fragile and freestanding microstructures. Release of high aspect ratio comb-drive microstructure of PMMA made by one-step x-ray lithography (OXL) is studied. The effect of low-surface tension Isopropyl alcohol (IPA) over water is investigated for release of the high aspect ratio microstructures using conventional and supercritical (SC) CO2 drying. The results of conventional drying are also compared for the samples released or dried in both in-house developed and commercial SC CO2 dryer. It is found that in all cases the microstructures of PMMA are permanently deformed and damaged while using SC CO2 for drying. For free-standing high aspect ratio microstructures of PMMA made by OXL, it is advised to use low-surface tension IPA over DI water. However, this brings a limitation on the design of the microstructure.

  1. Low-cost laser printable photomask: One-step, photoresist-free, fully solution processed high-grade photolithography mask (United States)

    Yun, Jinho; Kim, Jongsu; Yang, Minyang; Kang, Bongchul


    Owing to the short life cycle of present-day microelectronics, conventional method of photomask fabrication should be replaced in order to improve the resultant agility and productivity of photolithography. To fulfill these requirements, we suggest a fully solution-based one-step fabrication method of a high-grade photomask, without the use of a photoresist, vacuum deposition, and etching process. The photomask is fabricated via the laser-induced instantaneous thermochemical metallization of an optically catalyzed hybrid complex synthesized in-situ from a low-cost particle-free organometallic solution. This reaction yields a masking layer whose high selectivity of less than 1 μm, self-generated retroreflective structure, and excellent optical surface are comparable to those of masks fabricated by vacuum depositions. In addition, the complexity of the process is minimized owing to the solution deposition of all the constituent layers. A series of evaluations and the application of this method to an actual photolithography process confirm that this approach constitute a next-generation photomask fabrication method by satisfying both improved agility and productivity of microelectronics manufacturing.

  2. Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates (United States)

    Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu; Gong, Lijun; He, Wei


    The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O2sbnd CF4 low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of Csbnd O, Osbnd Cdbnd O, Cdbnd O and sbnd NO2 by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

  3. Negative ... concord?

    NARCIS (Netherlands)

    Giannakidou, A

    The main claim of this paper is that a general theory of negative concord (NC) should allow for the possibility of NC involving scoping of a universal quantifier above negation. I propose that Greek NC instantiates this option. Greek n-words will be analyzed as polarity sensitive universal

  4. Subminimal negation

    NARCIS (Netherlands)

    Colacito, A.; de Jongh, D.; Vargas Sandoval, A.L.

    Minimal logic, i.e., intuitionistic logic without the ex falso principle, is investigated in its original form with a negation symbol instead of a symbol denoting the contradiction. A Kripke semantics is developed for minimal logic and its sublogics with a still weaker negation by introducing a

  5. Negative Leadership (United States)


    Negative Leadership by Colonel David M. Oberlander United States Army United States Army War...SUBTITLE Negative Leadership 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Colonel David M...Dr. Richard C. Bullis Department of Command Leadership , and Management 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING

  6. The frequency-dependent AC photoresistance behavior of ZnO thin films grown on different sapphire substrates. (United States)

    Cholula-Díaz, Jorge L; Barzola-Quiquia, José; Videa, Marcelo; Yin, Chunhai; Esquinazi, Pablo


    Zinc oxide (ZnO) thin films were grown by pulsed layer deposition under an N 2 atmosphere at low pressures on a- and r-plane sapphire substrates. Structural studies using X-ray diffraction confirmed that all films had a wurtzite phase. ZnO thin films on a- and r-plane sapphire have grown with orientations along the [0002] and [112[combining macron]0] directions, respectively. Room temperature photoluminescence measurements indicate that the presence of native point defects (interstitial zinc, oxygen vacancies, oxygen antisites and zinc vacancies) is more preponderant for ZnO thin films grown on the r-plane sapphire substrate than the sample grown on the a-plane sapphire substrate. Room temperature impedance spectroscopy measurements were performed in an alternating current frequency range from 40 to 10 5 Hz in the dark and under normal light. An unusual positive photoresistance effect is observed at frequencies above 100 kHz, which we suggest to be due to intrinsic defects present in the ZnO thin films. Furthermore, an analysis of the optical time response revealed that the film grown on the r-plane sapphire substrate responds faster (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.05, 0.26 and 6.00 min, respectively) than the film grown on the a-plane sapphire substrate (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.10, 0.73 and 4.02 min, respectively).

  7. Strain-Mediated Inverse Photoresistivity in SrRuO3/La0.7Sr0.3MnO3Superlattices

    KAUST Repository

    Liu, Heng-Jui


    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. In the pursuit of novel functionalities by utilizing the lattice degree of freedom in complex oxide heterostructure, the control mechanism through direct strain manipulation across the interfaces is still under development, especially with various stimuli, such as electric field, magnetic field, light, etc. In this study, the superlattices consisting of colossal-magnetoresistive manganites La0.7Sr0.3MnO3 (LSMO) and photostrictive SrRuO3 (SRO) have been designed to investigate the light-dependent controllability of lattice order in the corresponding functionalities and rich interface physics. Two substrates, SrTiO3 (STO) and LaAlO3 (LAO), have been employed to provide the different strain environments to the superlattice system, in which the LSMO sublayers exhibit different orbital occupations. Subsequently, by introducing light, we can modulate the strain state and orbital preference of LSMO sublayers through light-induced expansion of SRO sublayers, leading to surprisingly opposite changes in photoresistivity. The observed photoresistivity decreases in the superlattice grown on STO substrate while increases in the superlattice grown on LAO substrate under light illumination. This work has presented a model system that demonstrates the manipulation of orbital-lattice coupling and the resultant functionalities in artificial oxide superlattices via light stimulus. A fascinating model system of optic-driven functionalities has been achieved by artificial superlattices consisting of manganite La0.7Sr0.3MnO3 (LSMO) and photostrictive SrRuO3 (SRO). With design of different initial strain and orbital states in superlattices, we can even control the photoresistivity of the superlattices in an opposite trend that cannot be achieved in pure single film.

  8. Development of Carbon Based optically Transparent Electrodes from Pyrolyzed Photoresist for the Investigation of Phenomena at Electrified Carbon-Solution Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Donner, Sebastian [Iowa State Univ., Ames, IA (United States)


    The work presented herein describes a fundamental investigations of carbon as electrode material by using the pyrolysis of photoresist to create an optically transparent material. The development of these carbon-based optically transparent electrodes (C-OTEs) enables investigations of molecular interactions within the electrical double layer, processes that are central to a wide range of important phenomena, including the impact of changes in the surface charge density on adsorption. The electrochemical importance of carbon cannot be understated, having relevance to separations and detection by providing a wide potential window and low background current in addition to being low cost and light weight. The interactions that govern the processes at the carbon electrode surface has been studied extensively. A variety of publications from the laboratories of McCreery and Kinoshita provide in depth summaries about carbon and its many applications in electrochemistry. These studies reveal that defects, impurities, oxidation, and a variety of functional groups create adsorption sites on carbon surfaces with different characteristics. The interest in C-OTEs was sparked by the desire to study and understand the behavior of individual molecules at electrified interfaces. It draws on the earlier development of Electrochemically Modulated Liquid Chromatography (EMLC), which uses carbon as the stationary phase. EMLC takes advantage of changing the applied potential to the carbon electrode to influence the retention behavior of analytes. However, perspectives gained from, for example, chromatographic measurements reflect the integrated response of a large ensemble of potentially diverse interactions between the adsorbates and the carbon electrode. Considering the chemically and physically heterogeneous surface of electrode materials such as glassy carbon, the integrated response provides little insight into the interactions at a single molecule level. To investigate individual

  9. Novel negative tone photodefinable low dielectric constant hybrid films (United States)

    Markley, Thomas J.; Weigel, Scott J.; Kretz, Chris P.


    Multifunctional films have the potential to reduce the number of processing steps to prepare various complex electronic devices and thereby reduce the cost of manufacturing the device and increase the throughput of the process. By combining low dielectric thin film and photoresist technologies into one material, such an advantage could be provided to electronics device markets. Air Products and Chemicals has discovered negative tone photodefinable films having dielectric constant values less than 3.0 that are developable in water and/or aqueous TMAH solutions. The low dielectric films produced via a novel reaction pathway involving the use of photoacid generators (PAGs) provides a versatile link to various feature sizes depending on the choice of radiation source and PAG used. Specific examples of film properties and processing latitude will be presented for these developmental materials.

  10. Micro-fabrication of three dimensional pyrolysed carbon microelectrodes

    DEFF Research Database (Denmark)


    The present invention relates in one aspect to a method of producing a three-dimensional microscale patterned resist template for a pyrolysed carbon microelectrode structure by means of UV-lithography. Coating a planar substrate with an epoxy-based negative photoresist, such as an SU-8 photoresist...... is characterized by a soft baking temperature below 70 °C. Repetitive coating and partial depth exposure allows for the fabrication of multiple level laterally interconnected structures. Carbonization of the resist template provides truly three-dimensional carbon microelectrode structures....

  11. Photoresists for Microlithography

    Indian Academy of Sciences (India)

    interdisciplinary area in organic chemistry and trying to balance the academic and .... Beaquerel of France in 1840 as it resisted or protected the substrate from light) and exposed to light [2]. The exposed ..... protect the desired areas of the wafer from etching, ion implan- tation, metallization, or other processes. Illumination ...

  12. Photoresists for Microlithography

    Indian Academy of Sciences (India)

    MCT based IR devices. His primary hobby is reading various subjects, scientific or otherwise and listening to music both Indian and western: classical and modem. S V Eswaran has worked on lac resin, heterocycles and nitrene·carbene conversion. Chemical education is his passion and his hobbies include reading, music,.

  13. Interference Lithography for Optical Devices and Coatings (United States)


    epoxy-based, negative photoresist commercially provided by Microchem Corporation.48 SU8 was designed for microelectronic applications, and is...used to spatially design the position of nanoparticles within a three-dimensional polymer nanocomposite.51 A nanoparticle/monomer mixture is used...microvascular networks137-139 to bring more material into the area of damage. The encapsulation approach involves adding microcapsules that contain a

  14. Sub-0.5-µm gate doped-channel field-effect transistors with HEMT-like channel using thermally reflowed photoresist and spin-on glass (United States)

    Tan, S. W.; Chen, W. T.; Chu, M. Y.; Lour, W. S.


    In this paper we report on a new sub-0.5-µm gate-length field-effect transistor (FET) processing technique by using conventional i-line optical lithography. The key methodology is to thermally reflow the patterned photoresist upon two-step spin-coated spin-on glass (SOG). According to this new process, the deposited gate metal has its final length and thickness separately determined by taped resist profile and SOG thickness. Furthermore, undercutting formed during isotropic etch SOG film is beneficial to the subsequent lift-off process, achieving high fabrication yield. The implemented gate length is as short as 0.41 µm. Then it was successfully applied to fabrication of a newly designed hetero-doped-channel FET (HDCFET) with digital-graded InxGa1-xAs multilayer forming a HEMT-like channel. This digital-graded InxGa1-xAs channel by changing x values from 0.1 to 0.2 has most electrons closer to the gate metal. The measured sheet carrier density and mobility are 4.3 × 1012 cm-2 and 3560 cm2 V-1 s-1, respectively, while the peak carrier concentration is larger than 1 × 1019 cm-3. A fabricated 0.41 × 100 µm2 HDCFET exhibits the maximum transconductance of 370 mS mm-1 with an output current larger than 535 mA mm-1 and ft(fmax) of 26 (32) GHz.

  15. Surface modification for patterned cell growth on substrates with pronounced topographies using sacrificial photoresist and parylene-C peel-off (United States)

    Larramendy, Florian; Yoshida, Shotaro; Jalabert, Laurent; Takeuchi, Shoji; Paul, Oliver


    A range of methods including soft lithography are available for patterning protein layers for cell adhesion on quasi-planar substrates. Suitably structured, these layers favor the geometrically constrained, controlled growth of cells and the development of cellular extensions on them. For this purpose, the ability to control the shape and dimension of cell-adhesive areas with high precision is crucial. For more advanced studies of cell interactions, the surface modification or functionalization of substrates with complex topographies is desirable. This paper describes a simple technique allowing to produce surface modification patterns using delicate molecules such as laminin on substrates exhibiting pronounced topographies with recessed and protruding microstructures. The technique is based on the combination of sacrificial photoresist structures with a connected parylene-C layer. This layer locally adheres to the substrate wherever the substrate needs to be protected against the surface modification. After surface modification, the parylene-C layer is peeled off. Patterns comprising arbitrary networks of modified and unmodified substrate areas can thus be realized. We demonstrate the technique with the guided growth of neuron-like PC12 cells on networks of laminin lines on substrates structured with micropillars and microwells.

  16. Negation and negative concord in romance

    NARCIS (Netherlands)

    Swart, Henriëtte de; Sag, I.A.

    This paper addresses the two interpretations a combination of negative indefinites can get in concord languages like French, namely a concord reading which amounts to a single negation, or a double negation reading. We develop an analysis in a polyadic framework, in which a sequence of

  17. Electromagnetic properties of photodefinable barium ferrite polymer composites

    Directory of Open Access Journals (Sweden)

    Olusegun Sholiyi


    Full Text Available This article reports the magnetic and microwave properties of a Barium ferrite powder suspended in a polymer matrix. The sizes for Barium hexaferrite powder are 3–6 μm for coarse and 0.8–1.0 μm for the fine powder. Ratios 1:1 and 3:1 (by mass of ferrite to SU8 samples were characterized and analyzed for predicting the necessary combinations of these powders with SU8 2000 Negative photoresist. The magnetization properties of these materials were equally determined and were analyzed using Vibrating Sample Magnetometer (VSM. The Thru, Reflect, Line (TRL calibration technique was employed in determining complex relative permittivity and permeability of the powders and composites with SU8 between 26.5 and 40 GHz.

  18. Polemic and Descriptive Negations

    DEFF Research Database (Denmark)

    Horslund, Camilla Søballe


    to semantics and pragmatics, negations can be used in three different ways, which gives rise to a typology of three different types of negations: 1) the descriptive negation, 2) the polemic negation, and 3) the meta-linguistic negation (Nølke 1999, 4). This typology illuminates the fact that the negation...... as such may be more or less central to the meaning of the utterance. The present paper investigates the role of morphosyntactic and prosodic prominence as well as register and social setting on the interpretation of negations. It seems plausible to expect that if the negation as such is central to the meaning...... of the utterance (as in polemic negations), the negation will be articulated prominently in order to emphasise this importance. Likewise, if the negation is not central to the meaning of the utterance, it should not be articulated prominently. Moreover, it is plausible to expect descriptive negations to be more...

  19. Flip-chip integration of Si bare dies on polymeric substrates at low temperature using ICA vias made in dry film photoresist (United States)

    Vásquez Quintero, Andrés; Briand, Danick; de Rooij, Nico F.


    In this paper, a low temperature flip-chip integration technique for Si bare dies is demonstrated on flexible PET substrates with screen-printed circuits. The proposed technique is based on patterned blind vias in dry film photoresist (DP) filled with isotropic conductive adhesive (ICA). The DP material serves to define the vias, to confine the ICA paste (80 µm-wide and potentially 25 µm-wide vias), as an adhesion layer to improve the mechanical robustness of the assembly, and to protect additional circuitry on the substrate. The technique is demonstrated using gold-bumped daisy chain chips (DCCs), with electrical vias resistances in the order to hundreds of milliohms, and peel/shear adhesion strengths of 0.7 N mm-1 and 3.2 MPa, respectively, (i.e. at 1.2 MPa of bonding pressure). Finally, the mechanical robustness to bending forces was optimized through flexural mechanics models by placing the neutral plane at the DCC/DP adhesive interface. The optimization was performed by reducing the Si thickness from 400 to 37 µm, and resulted in highly robust integrated assemblies withstanding 10 000 cycles of dynamic bending at 40 mm of radius, with relative changes in vias resistance lower than 20%. In addition, the electrical vias resistance and adhesion strengths were compared to samples integrated with anisotropic conductive adhesives (ACAs). Besides the low temperature and high integration resolution, the proposed method is compatible with large area fabrication and multilayer architectures on foil.

  20. Photochemical modification and patterning of SU-8 using Anthraquinone photolinkers

    DEFF Research Database (Denmark)

    Blagoi, Gabriela; Keller, Stephan Urs; Persson, Karl Fredrik


    of micropatterned AQ molecules is improved to 1.5 μm when a collimated light source is used. This micropatterning process will be important for the functionalization of MEMS-based biosensors. The method saves several processing steps and can be integrated in cleanroom fabrication thus avoiding contamination...

  1. Simulation of SU-8 frequency-driven scratch drive actuators

    KAUST Repository

    Conchouso Gonzalez, David


    This paper presents the simulation of Scratch Drive Actuators (SDAs) for micro-robotic applications. SDAs use electrostatic forces to generate motion on top of an interdigitated electrode array. The purpose of this investigation is to evaluate several design geometries and micro-actuator configurations using ConventorWare®\\'s finite element analysis module. The study performed investigates the SDAs modal and electrostatic behavior and the effects of linking two or more SDAs together in a microrobot device. In addition, the interdigitated electrode array performance, used for power delivery, was studied by changing the thickness of its dielectric layer. We present our observations based on these studies, which will aid in the understanding and development of future SDA designs. © 2013 IEEE.

  2. Negative indefinites in Afrikaans


    Huddlestone, K.M.


    This dissertation is concerned with the syntactic and semantic status of negative indefinites in Afrikaans. The problem posed by negative indefinites is that their interpretation appears to differ across double negation (DN) and negative concord (NC) languages. With respect to negative indefinites, Afrikaans displays features that distinguish it from both typical NC and typical DN languages. Contrary to most NC languages, and similarly to DN languages, standard Afrikaans does not allow negati...

  3. Negative energy; L'energie negative

    Energy Technology Data Exchange (ETDEWEB)

    Ford, L. [Tufts Univ., Medford, MA (United States); Roman, Th. [Connecticut Univ., Farmington, CT (United States)


    We could travel at light velocity or more if we mastered a new form of energy called negative energy. This energy is predicted by the quantum theory and follows from the Heisenberg principle applied to the void. In the void the density of energy is null in average but in fact fluctuates around zero according to the quantum theory, so we can find places with negative energy. This concept has nothing to do with antimatter or with the energy introduced in the recent theories of anti-gravity. According to the theory of general relativity the presence of matter and energy distorts the space-time geometry. In the presence of negative energy strange phenomena might happen. A tunnel could bridge 2 distant points in the universe, and inside it travelling at light velocity or more would be possible. (A.C.)

  4. Acquiring negative polarity items

    NARCIS (Netherlands)

    Lin, J.


    Negative Polarity Items (NPIs) are words or expressions that exhibit a restricted distribution to certain negative contexts only. For example, yet is an NPI and must appear in the scope of a negation: Mary has *(not) finished yet. The existence of NPIs such as yet gives rise to a learnability

  5. Negative Ion Density Fronts

    Energy Technology Data Exchange (ETDEWEB)

    Igor Kaganovich


    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  6. Negative-tone resist system using vinyl cyclic acetal crosslinker (United States)

    Huang, Wu-Song; Lee, Kim Y.; Chen, K. Rex; Schepis, Dominic


    Most high performance negative tone resists are chemically amplified systems. The chemistry involves a creation of acid during photo-exposure and subsequent crosslinking of the polymer matrix during post-exposure bake. The commonly used crosslinkers are epoxies, melamines, benzyl alcohol and benzyl acetates. In light of the high reactivity of vinyl group on vinyl ether type compounds, literature has suggested that photochemical addition reaction of a polymer- bearing pendant vinyl ether with various thiol compounds can potentially be highly sensitive negative-type photoresists. Recently, bis-dihydropyrane derivative has been used for the first time to develop high performance negative tone resists for DUV, E-beam and x-ray applications. A cyclic acetal system based on acetal blocked aromatic aldehyde has also been demonstrated to be a good crosslinker for negative DUV resist. In order to take advantage of the above chemistries, we have investigated a crosslinker, 3,9-divinylspirobi(M-dioxane) (DVSDO), which contains both cyclic acetal groups and vinyl groups. Different loadings of DVSDO from 8% to 17% were formulated in combination with triphenyl sulfonyl triflate and N-sulfonyl triflate derivatives in polyhydroxystyrene matrix. One composition contains 8% N- sulfonyloxy derivative, 12% DVSDO in 20% solid of polyhydroxystyrene has shown resolution to 0.35 micrometer from Canon 0.37 NA DUV stepper. It also shows promising resolution in E-beam lithography. Varying the post apply bake (PAB) temperatures and post exposure bake temperatures (PEB) demonstrate a great dependency of sensitivity to baking temperature. The sensitivity increases with decreasing PAB, while decreases with decreasing PEB. Insufficient baking time (less than 4 - 5 minutes) at lower PEB temperature 90 degrees Celsius causes significant film loss after development in 0.14N TMAH for 60 - 75s. On the other hand, when the PEB temperature is too high (greater than 120 degrees Celsius), the resist

  7. Isotropic Single Negative Metamaterials

    Directory of Open Access Journals (Sweden)

    P. Protiva


    Full Text Available This paper presents the application of simple, and therefore cheap, planar resonators for building 3D isotropic metamaterials. These resonators are: a broadside-coupled split ring resonator with a magnetic response providing negative permeability; an electric dipole terminated by a loop inductor together with a double H-shaped resonator with an electric response providing negative permittivity. Two kinds of 3D isotropic single negative metamaterials are reported. The first material consists of unit cells in the form of a cube bearing on its faces six equal planar resonators with tetrahedral symmetry. In the second material, the planar resonators boxed into spherical plastic shells and randomly distributed in a hosting material compose a real 3D volumetric metamaterial with an isotropic response. In both cases the metamaterial shows negative permittivity or permeability, according to the type of resonators that are used. The experiments prove the isotropic behavior of the cells and of the metamaterial specimens.

  8. Meningitis - gram-negative (United States)

    ... life-threatening illness. Prevention Prompt treatment of related infections may reduce the risk of meningitis. Alternative Names Gram-negative meningitis Images Central nervous system and peripheral nervous ...

  9. Nanofabrication of planar split ring resonators for negative refractive index metamaterials in the infrared range

    Directory of Open Access Journals (Sweden)



    Full Text Available Experimental nanofabrication of planar structures for one-dimensional metamaterials designed to achieve a negative effective refractive index in the mid-infrared range (5–10 micrometers was performed. Double split ring and complementary double split ring resonators (SRR and CSRR with square and circular geometries, were chosen to be fabricated since these are the basic building blocks to achieve a negative effective dielectric permittivity and magnetic permeability. Scanning probe nanolithography with z-scanner movement was used to fabricate straight-line and curvilinear segments with a line width of 80 – 120 nm. The geometries were delineated in 20 nm thin silver layers sputter-deposited on a positive photoresist substrate spin-coated on polished single crystal silicon wafers, as well as on polycarbonate slabs. The morphology of the structures was characterized by atomic force microscopy. The feature repeatibility was 60 – 150 nm, depending on the process conditions and the feature complexity. The nanolithographic groove depth in different samples ranged from 4 nm to 80 nm.


    Directory of Open Access Journals (Sweden)

    Dedy Subandowo -


    Full Text Available Abstract: This research entitled "Negation Affixes in English". This study is aimed to describe the various negation affixes in English, morphological process, morphophonemic and meaning. The research data were taken from various sources of English grammar book, morphology, research journal and the book which relatees to the research. English grammar books used in this study are written by Otto Jesperson, Marcella Frank, Greenbaum and Geoffrey Leech.  The method used in this research is the descriptive-qualitative method. While the data collection techniques are performed by using jot-down method. And the results of analysis are presented in tabular form and descriptive method. The result of the research shows that English has six types of negative affixes which are categorized by the intensity of its appearance, such as dis-, in-, non-, un-, anti- and -less. Based on the function, negation affixes are divided into several categories such as adjectives, nouns, verbs, and adverbs. The morphophonemic affix in- has four allomorphs, they are in-, im-, il- and ir- . While the analysis revealed that negation affixes have some basic meanings, such as ‘not’, ‘without’, and ‘anti’.

  11. Nedtrykt af negative nyheder

    DEFF Research Database (Denmark)

    Skovsgaard, Morten; Søberg, Pernille Frantz


    I adskillige år er det blevet debatteret, hvorvidt nyhedernes negative fokus har konsekvenser for borgerne, og om det i sid-ste ende får flere til at vende ryggen til nyhederne. Vores viden om effekterne af positive og negative nyheder er dog begrænset, og derfor undersøges det i denne artikel......, hvordan henholdsvis positive og negative tv-nyheder påvirker seernes humør, hukom-melse af information fra indslaget og lyst til at se yderligere tv-nyheder. Det gør vi i et survey-eksperiment (N=204), hvor tre grupper så enten et originalt indslag eller det samme indslag klippet med henholdsvis et...

  12. The Negative Repetition Effect (United States)

    Mulligan, Neil W.; Peterson, Daniel J.


    A fundamental property of human memory is that repetition enhances memory. Peterson and Mulligan (2012) recently documented a surprising "negative repetition effect," in which participants who studied a list of cue-target pairs twice recalled fewer targets than a group who studied the pairs only once. Words within a pair rhymed, and…

  13. Depressionens negative spiral

    DEFF Research Database (Denmark)

    Munk, Karen


    Artiklen formidler resultater fra en longitudinel undersøgelse af det selvforstærkende, negative samspil imellem udvikling og vedligeholdelse af alderdomsdepression via primære miljøbelastninger og via  den deprimerede ældre som belastning for miljøet, som i sin tur "svarer negativt" på lidelsen og...

  14. Oxide nanoparticle EUV resists: toward understanding the mechanism of positive and negative tone patterning

    KAUST Repository

    Chakrabarty, Souvik


    DUV, EUV and e-beam patterning of hybrid nanoparticle photoresists have been reported previously by Ober and coworkers. The present work explores the underlying mechanism that is responsible for the dual tone patterning capability of these photoresist materials. Spectroscopic results correlated with mass loss and dissolution studies suggest a ligand exchange mechanism responsible for altering the solubility between the exposed and unexposed regions. © 2013 SPIE.

  15. Piezoresistive polymer composites for cantilever readout

    DEFF Research Database (Denmark)

    Lillemose, Michael

    . Conducting polymer composites consisting of SU-8 (an epoxy based photoresist) and dierent concentrations of carbon- and silver nanoparticles have been investigated. For the carbon nanoparticle doped SU-8 composites, a positive piezoresistive eect was measured, with the largest eect towards the lower...... concentrations. No signicant piezoresistive eect was observed for the silver nanoparticle doped composites. Thin lm structures of the intrinsically conductive polymer, polyaniline, have been fabricated and a negative piezoresistive eect was observed. Thin gold lms were investigated, with the aim of measuring...... thin lm can be strained, while measuring how the resistance changes. This allows the determination of the strain sensitivity of the materials. Three qualitatively dierent material types have been investigated: conductive polymer composites, an intrinsically conductive polymer and thin gold lms...

  16. Hybrid UV Lithography for 3D High-Aspect-Ratio Microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sungmin; Nam, Gyungmok; Kim, Jonghun; Yoon, Sang-Hee [Inha Univ, Incheon (Korea, Republic of)


    Three-dimensional (3D) high-aspect-ratio (HAR) microstructures for biomedical applications (e.g., microneedle, microadhesive, etc.) are microfabricated using the hybrid ultraviolet (UV) lithography in which inclined, rotational, and reverse-side UV exposure processes are combined together. The inclined and rotational UV exposure processes are intended to fabricate tapered axisymmetric HAR microstructures; the reverse-side UV exposure process is designed to sharpen the end tip of the microstructures by suppressing the UV reflection on a bottom substrate which is inevitable in conventional UV lithography. Hybrid UV lithography involves fabricating 3D HAR microstructures with an epoxy-based negative photoresist, SU-8, using our customized UV exposure system. The effects of hybrid UV lithography parameters on the geometry of the 3D HAR microstructures (aspect ratio, radius of curvature of the end tip, etc.) are measured. The dependence of the end-tip shape on SU-8 soft-baking condition is also discussed.

  17. Loading of Drug-Polymer Matrices in Microreservoirs for Oral Drug Delivery

    DEFF Research Database (Denmark)

    Petersen, Ritika Singh; Keller, Stephan Sylvest; Boisen, Anja


    loading in microfabricated DDS. The microfabricated DDS are microcontainers fabricated in photoresist SU-8 and biopolymer poly-L-lactic-acid (PLLA). Furosemide (F) drug is embedded in poly-ε-caprolactone (PCL) polymer matrix. This F-PCL drug polymer matrix is loaded in SU-8 and PLLA microcontainers using...

  18. Negative leave balances

    CERN Multimedia

    Human Resources Department


    Members of the personnel entitled to annual leave and, where appropriate, saved leave and/or compensatory leave are requested to take note of the new arrangements described below, which were recommended by the Standing Concertation Committee (SCC) at its meeting on 1Â September 2005 and subsequently approved by the Director-General. The changes do not apply to members of the personnel participating in the Progressive Retirement Programme (PRP) or the Part-time Work as a pre-retirement measure, for whom the specific provisions communicated at the time of joining will continue to apply. Â Negative balances in annual leave, saved leave and/or compensatory leave accounts at the end of the leave year (30th September) and on the date on which bonuses are credited to the saved leave account (31st December): Where members of the personnel have a leave account with a negative balance on 30Â September and/or 31Â December, leave will automatically be transferred from one account to another on the relevant dates i...

  19. Negative leave balances

    CERN Multimedia

    Human Resources Department


    Members of the personnel entitled to annual leave and, where appropriate, saved leave and/or compensatory leave are requested to take note of the new arrangements described below, which were recommended by the Standing Concertation Committee (SCC) at its meeting on 1 September 2005 and subsequently approved by the Director-General. The changes do not apply to members of the personnel participating in the Progressive Retirement Programme (PRP) or the Part-time Work as a pre-retirement measure, for whom the specific provisions communicated at the time of joining will continue to apply.  Negative balances in annual leave, saved leave and/or compensatory leave accounts at the end of the leave year (30th September) and on the date on which bonuses are credited to the saved leave account (31st December): Where members of the personnel have a leave account with a negative balance on 30 September and/or 31 December, leave will automatically be transferred from one account to another on the relevant dates in or...

  20. Design and fabrication of a multi-focusing artificial compound eyes with negative meniscus substrate (United States)

    Luo, Jiasai; Guo, Yongcai; Wang, Xin; Fan, Fenglian


    Miniaturized artificial compound eyes with a large field of view (FOV) have potential application in the area of micro-optical-electro-mechanical-system (MOEMS). A new non-uniform microlens array (MLA) on a negative meniscus substrate, fabricated by the melting photoresist method, was proposed in this paper. The multi-focusing MLA reduced the defocus effectively, which was caused by the uniform array on a spherical substrate. Moreover, like most ommatidia in compound eyes, each microlens of the multi-focusing MLA was arranged in one of the eleven concentric circles. In order to match with the multi-focusing MLA and avoid the total reflection, the negative meniscus substrate was fabricated by a homebuilt mold with a micro-hole array and polydimethylsiloxane coelomic compartment attached. The coelomic compartment is capable of offering an excellent injection environment without bubbles and impurities. Due to the direct 3D implementation of the MLA, rich available materials can be used by this method without substrate reshaping. As the molding material, the ultraviolet curing adhesive NOA81 can be cured within ten few seconds under ultraviolet which relieve intensive labor and protect the stereolithography apparatus effectively. The experimental results show that this new MLA has a better imaging performance, higher light usage efficiency and larger FOV because of the negative meniscus and multi-focusing MLA. Moreover, due to the homebuilt mold, more accurate geometrical parameters and shorter processing cycle were realized. Accordingly, together with an appropriate hardware, this MLA has diverse potential applications in medical imaging, military and machine vision.

  1. Do `negative' temperatures exist? (United States)

    Lavenda, B. H.


    A modification of the second law is required for a system with a bounded density of states and not the introduction of a `negative' temperature scale. The ascending and descending branches of the entropy versus energy curve describe particle and hole states, having thermal equations of state that are given by the Fermi and logistic distributions, respectively. Conservation of energy requires isentropic states to be isothermal. The effect of adiabatically reversing the field is entirely mechanical because the only difference between the two states is their energies. The laws of large and small numbers, leading to the normal and Poisson approximations, characterize statistically the states of infinite and zero temperatures, respectively. Since the heat capacity also vanishes in the state of maximum disorder, the third law can be generalized in systems with a bounded density of states: the entropy tends to a constant as the temperature tends to either zero or infinity.

  2. UV-LIGA: From Development to Commercialization

    Directory of Open Access Journals (Sweden)

    Grégoire Genolet


    Full Text Available A major breakthrough in UV-LIGA (Lithographie, Galvanoformung and Abformung started with the use of epoxy-based EPON® SU-8 photoresist in the mid-1990s. Using this photoresist has enabled the fabrication of tall and high aspect ratio structures without the use of a very expensive synchrotron source needed to expose the photoresist layer in X-ray LIGA. SU-8 photoresist appeared to be well-suited for LIGA templates, but also as a permanent material. Based on UV-LIGA and SU-8, Mimotec SA has developed processes to manufacture mold inserts and metallic components for various market fields. From one to three-level parts, from Ni to other materials, from simple to complicated parts with integrated functionalities, UV-LIGA has established itself as a manufacturing technology of importance for prototyping, as well as for mass-fabrication. This paper reviews some of the developments that led to commercial success in this field.

  3. Coagulase-Negative Staphylococci (United States)

    Heilmann, Christine; Peters, Georg


    SUMMARY The definition of the heterogeneous group of coagulase-negative staphylococci (CoNS) is still based on diagnostic procedures that fulfill the clinical need to differentiate between Staphylococcus aureus and those staphylococci classified historically as being less or nonpathogenic. Due to patient- and procedure-related changes, CoNS now represent one of the major nosocomial pathogens, with S. epidermidis and S. haemolyticus being the most significant species. They account substantially for foreign body-related infections and infections in preterm newborns. While S. saprophyticus has been associated with acute urethritis, S. lugdunensis has a unique status, in some aspects resembling S. aureus in causing infectious endocarditis. In addition to CoNS found as food-associated saprophytes, many other CoNS species colonize the skin and mucous membranes of humans and animals and are less frequently involved in clinically manifested infections. This blurred gradation in terms of pathogenicity is reflected by species- and strain-specific virulence factors and the development of different host-defending strategies. Clearly, CoNS possess fewer virulence properties than S. aureus, with a respectively different disease spectrum. In this regard, host susceptibility is much more important. Therapeutically, CoNS are challenging due to the large proportion of methicillin-resistant strains and increasing numbers of isolates with less susceptibility to glycopeptides. PMID:25278577

  4. Negative legacy of obesity.

    Directory of Open Access Journals (Sweden)

    Kohsuke Shirakawa

    Full Text Available Obesity promotes excessive inflammation, which is associated with senescence-like changes in visceral adipose tissue (VAT and the development of type 2 diabetes (T2DM and cardiovascular diseases. We have reported that a unique population of CD44hi CD62Llo CD4+ T cells that constitutively express PD-1 and CD153 exhibit cellular senescence and cause VAT inflammation by producing large amounts of osteopontin. Weight loss improves glycemic control and reduces cardiovascular disease risk factors, but its long-term effects on cardiovascular events and longevity in obese individuals with T2DM are somewhat disappointing and not well understood. High-fat diet (HFD-fed obese mice were subjected to weight reduction through a switch to a control diet. They lost body weight and visceral fat mass, reaching the same levels as lean mice fed a control diet. However, the VAT of weight reduction mice exhibited denser infiltration of macrophages, which formed more crown-like structures compared to the VAT of obese mice kept on the HFD. Mechanistically, CD153+ PD-1+ CD4+ T cells are long-lived and not easily eliminated, even after weight reduction. Their continued presence maintains a self-sustaining chronic inflammatory loop via production of large amounts of osteopontin. Thus, we concluded that T-cell senescence is essentially a negative legacy effect of obesity.

  5. Negative Expertise: Comparing Differently Tenured Elder Care Nurses' Negative Knowledge (United States)

    Gartmeier, Martin; Lehtinen, Erno; Gruber, Hans; Heid, Helmut


    Negative expertise is conceptualised as the professional's ability to avoid errors during practice due to certain cognitive agencies. In this study, negative knowledge (i.e. knowledge about what is wrong in a certain context and situation) is conceptualised as one such agency. This study compares and investigates the negative knowledge of elder…

  6. Negative Ions in Space. (United States)

    Millar, Thomas J; Walsh, Catherine; Field, Thomas A


    Until a decade ago, the only anion observed to play a prominent role in astrophysics was H - . The bound-free transitions in H - dominate the visible opacity in stars with photospheric temperatures less than 7000 K, including the Sun. The H - anion is also believed to have been critical to the formation of molecular hydrogen in the very early evolution of the Universe. Once H 2 formed, about 500 000 years after the Big Bang, the expanding gas was able to lose internal gravitational energy and collapse to form stellar objects and "protogalaxies", allowing the creation of heavier elements such as C, N, and O through nucleosynthesis. Although astronomers had considered some processes through which anions might form in interstellar clouds and circumstellar envelopes, including the important role that polycyclic aromatic hydrocarbons might play in this, it was the detection in 2006 of rotational line emission from C 6 H - that galvanized a systematic study of the abundance, distribution, and chemistry of anions in the interstellar medium. In 2007, the Cassini mission reported the unexpected detection of anions with mass-to-charge ratios of up to ∼10 000 in the upper atmosphere of Titan; this observation likewise instigated the study of fundamental chemical processes involving negative ions among planetary scientists. In this article, we review the observations of anions in interstellar clouds, circumstellar envelopes, Titan, and cometary comae. We then discuss a number of processes by which anions can be created and destroyed in these environments. The derivation of accurate rate coefficients for these processes is an essential input for the chemical kinetic modeling that is necessary to fully extract physics from the observational data. We discuss such models, along with their successes and failings, and finish with an outlook on the future.

  7. The case for negative senescence

    DEFF Research Database (Denmark)

    Vaupel, James W; Baudisch, Annette; Dölling, Martin


    Negative senescence is characterized by a decline in mortality with age after reproductive maturity, generally accompanied by an increase in fecundity. Hamilton (1966) ruled out negative senescence: we adumbrate the deficiencies of his model. We review empirical studies of various plants and some...... kinds of animals that may experience negative senescence and conclude that negative senescence may be widespread, especially in indeterminate-growth species for which size and fertility increase with age. We develop optimization models of life-history strategies that demonstrate that negative senescence...

  8. Negative Attitudes, Network and Education

    DEFF Research Database (Denmark)

    Bennett, Patrick; la Cour, Lisbeth; Larsen, Birthe

    We consider the impact of negative attitudes against immigrants and immigration on educational choice in a search and wage bargaining model including networking. We consider two cases in terms of the importance of negative attitudes againts immigrants for high and low educated individuals and find...... that more negative attitudes against immigrants has a positive impact on education in one case and a negative impact in the other and has no impact on natives. Immigration improves employment perspectives for immigrants and thereby increases immigrant education whereas endogenous negative attitudes lead...... to an ambiguous impact. Empirically, we consider immigrants’ high school attendance. On the macro-level, we confirm a signficant negative correlation between negative attitudes towards immigrants and high school attendance and a positive impact of networking on high school attendance. On the individual level, we...

  9. Negative snakes in JET: evidence for negative shear

    Energy Technology Data Exchange (ETDEWEB)

    Gill, R.D.; Alper, B.; Edwards, A.W. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Pearson, D. [Reading Univ. (United Kingdom)


    The signature of the negative snakes from the soft X-ray cameras is very similar to the more usual snakes except that the localised region of the snake has, compared with its surroundings, decreased rather than increased emission. Circumstances where negative snakes have been seen are reviewed. The negative snake appears as a region of increased resistance and of increased impurity density. The relationship between the shear and the current perturbation is shown, and it seem probable that the magnetic shear is reversed at the point of the negative snake, i.e. that q is decreasing with radius. 6 refs., 6 figs.

  10. Nanomechanical Pyrolytic Carbon Resonators: Novel Fabrication Method and Characterization of Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Maksymilian Kurek


    Full Text Available Micro- and nanomechanical string resonators, which essentially are highly stressed bridges, are of particular interest for micro- and nanomechanical sensing because they exhibit resonant behavior with exceptionally high quality factors. Here, we fabricated and characterized nanomechanical pyrolytic carbon resonators (strings and cantilevers obtained through pyrolysis of photoresist precursors. The developed fabrication process consists of only three processing steps: photolithography, dry etching and pyrolysis. Two different fabrication strategies with two different photoresists, namely SU-8 2005 (negative and AZ 5214e (positive, were compared. The resonant behavior of the pyrolytic resonators was characterized at room temperature and in high vacuum using a laser Doppler vibrometer. The experimental data was used to estimate the Young’s modulus of pyrolytic carbon and the tensile stress in the string resonators. The Young’s moduli were calculated to be 74 ± 8 GPa with SU-8 and 115 ± 8 GPa with AZ 5214e as the precursor. The tensile stress in the string resonators was 33 ± 7 MPa with AZ 5214e as the precursor. The string resonators displayed maximal quality factor values of up to 3000 for 525-µm-long structures.

  11. Wages, Amenities and Negative Attitudes

    DEFF Research Database (Denmark)

    Waisman, Gisela; Larsen, Birthe

    We exploit the regional variation in negative attitudes towards immigrants to Sweden in order to analyse the consequences of the attitudes on immigrants welfare. We find that attitudes towards immigrants are of importance: they both affect their labour market outcomes and their quality of life. W...... interpret the negative effect on wages as evidence of labour market discrimination. We estimate the welfare effects of negative attitudes, through their wage and local amenities, for immigrants with different levels of skills, origin, gender and age....

  12. Prestarlike functions with negative coefficients

    Directory of Open Access Journals (Sweden)

    H. Silverman


    Full Text Available The extreme points for prestarlike functions having negative coefficients are determined. Coefficient, distortion and radii of univalence, starlikeness, and convexity theorems are also obtained.

  13. Income, Amenities and Negative Attitudes

    DEFF Research Database (Denmark)

    Waisman, Gisela; Larsen, Birthe


    We exploit the regional variation in negative attitudes towards immigrants to Sweden in order to analyse the consequences of negative attitudes on refugees’ utility from labour income and amenities. We find that attitudes towards immigrants are important: while they affect mainly the refugees......’ quality of life, they also affect their income. We estimate the utility effects of negative attitudes for refugees with different levels of education and gender. We also analyse how the size of the refugees’ networks relate to their quality of life and income as well as how negative attitudes towards...

  14. Causality, Nonlocality, and Negative Refraction. (United States)

    Forcella, Davide; Prada, Claire; Carminati, Rémi


    The importance of spatial nonlocality in the description of negative refraction in electromagnetic materials has been put forward recently. We develop a theory of negative refraction in homogeneous and isotropic media, based on first principles, and that includes nonlocality in its full generality. The theory shows that both dissipation and spatial nonlocality are necessary conditions for the existence of negative refraction. It also provides a sufficient condition in materials with weak spatial nonlocality. These fundamental results should have broad implications in the theoretical and practical analyses of negative refraction of electromagnetic and other kinds of waves.

  15. Negative supervisionsoplevelser og deres konsekvenser

    DEFF Research Database (Denmark)

    Nielsen, Jan


    in evaluation. First part of the paper explores negative experience in supervision in general. The second part, focusing on negative experience in supervision caused by evaluation, is explored and discussed in relation to the key concept of supervisory alliance (Bordin, 1983), perceiving evaluation...

  16. Research priorities for negative emissions

    NARCIS (Netherlands)

    Fuss, S.; Jones, C. D.; Kraxner, F.; Peters, G. P.; Smith, P.; Tavoni, M.; van Vuuren, Detlef|info:eu-repo/dai/nl/11522016X; Canadell, J. G.; Jackson, R. B.; Milne, J.; Moreira, J. R.; Nakicenovic, N.; Sharifi, A.; Yamagata, Y.


    Carbon dioxide removal from the atmosphere (CDR) - also known as 'negative emissions' - features prominently in most 2 °C scenarios and has been under increased scrutiny by scientists, citizens, and policymakers. Critics argue that 'negative emission technologies' (NETs) are insufficiently mature to

  17. Fabrication of electro-wetting liquid lenticular lens by using diffuser (United States)

    Sim, Jee Hoon; Kim, Junoh; Kim, Cheoljoong; Shin, Dooseub; Lee, Junsik; Koo, Gyo Hyun; Won, Yong Hyub


    Liquid lenticular multi-view system has great potential of three dimensional image realization. This paper aims to introduce a novel fabrication method of electro-wetting liquid lenticular lens using diffuser. The liquid lenticular device consists of a Ultraviolet (UV) adhesive chamber, two immiscible liquids and a sealing plate. The diffuser makes UV light spread slantly not directly to negative photoresist on a glass substrate. In this process, Su-8, the suitable material to fabricate a structure in high stature, is selected for negative photoresist. After forming a Su-8 chamber, the UV adhesive chamber is made through a PDMS sub-chamber that is made from the Su-8 chamber. As such, this research shows a result of a liquid lenticular lens having slanted side walls with an angle of 75 degrees. The UV adhesive chamber having slanted side walls is more advantageous for electro-wetting effect achieving high diopter than the chamber having vertical side walls. After that, gold is evaporated for electrode, and Parylene C and Teflon AF1600 is deposited for dielectric and hydrophobic layer respectively. For two immiscible liquids, DI water and a blend of 1-Chloronaphthalene and Dodecane with specific portions are used. Two immiscible liquids are injected in underwater environment and a glass that is coated with ITO on one side is sealed by UV adhesive. The completed tunable lenticular lens can switch two and three dimensional images by using electro-wetting principle that changes surface tensions by applying voltage. Also, dioptric power and response time of the liquid lenticular lens array are measured.

  18. TOPICAL REVIEW: Negative thermal expansion (United States)

    Barrera, G. D.; Bruno, J. A. O.; Barron, T. H. K.; Allan, N. L.


    There has been substantial renewed interest in negative thermal expansion following the discovery that cubic ZrW2O8 contracts over a temperature range in excess of 1000 K. Substances of many different kinds show negative thermal expansion, especially at low temperatures. In this article we review the underlying thermodynamics, emphasizing the roles of thermal stress and elasticity. We also discuss vibrational and non-vibrational mechanisms operating on the atomic scale that are responsible for negative expansion, both isotropic and anisotropic, in a wide range of materials.

  19. Negative Attitudes, Network and Education

    DEFF Research Database (Denmark)

    Bennett, Patrick; la Cour, Lisbeth; Larsen, Birthe

    This paper explores potential explanations behind the educational gap between young natives and immigrants using two measures, negative attitudes towards immigrants and networking, which may influence natives and immigrants differently. The paper considers, both theoretically and empirically......, the impact of negative attitudes and networking taking into account that these parameters may influence high and uneducated workers as well as immigrants and natives differently, creating different incentives to acquire education for the two ethnic groups. Using rich Danish administrative data, this paper...... finds evidence that greater negative attitudes increase incentives for males to acquire education and that networking also increases immigrant education....

  20. Adjective metaphors evoke negative meanings. (United States)

    Sakamoto, Maki; Utsumi, Akira


    Previous metaphor studies have paid much attention to nominal metaphors and predicative metaphors, but little attention has been given to adjective metaphors. Although some studies have focused on adjective metaphors, they only examined differences in the acceptability of various types of adjective metaphors. This paper explores the cognitive effects evoked by adjective metaphors. Three psychological experiments revealed that (1) adjective metaphors, especially those modified by color adjectives, tend to evoke negative effect; (2) although the meanings of metaphors are basically affected by the meanings of their vehicles, when a vehicle has a neutral meaning, negative meanings are evoked most frequently for adjective metaphors compared to nominal and predicative metaphors; (3) negative meanings evoked by adjective metaphors are related to poeticness, and poetic metaphors evoke negative meanings more easily than less poetic metaphors. Our research sheds new light on studies of the use of metaphor, which is one of the most basic human cognitive abilities.

  1. Adjective metaphors evoke negative meanings.

    Directory of Open Access Journals (Sweden)

    Maki Sakamoto

    Full Text Available Previous metaphor studies have paid much attention to nominal metaphors and predicative metaphors, but little attention has been given to adjective metaphors. Although some studies have focused on adjective metaphors, they only examined differences in the acceptability of various types of adjective metaphors. This paper explores the cognitive effects evoked by adjective metaphors. Three psychological experiments revealed that (1 adjective metaphors, especially those modified by color adjectives, tend to evoke negative effect; (2 although the meanings of metaphors are basically affected by the meanings of their vehicles, when a vehicle has a neutral meaning, negative meanings are evoked most frequently for adjective metaphors compared to nominal and predicative metaphors; (3 negative meanings evoked by adjective metaphors are related to poeticness, and poetic metaphors evoke negative meanings more easily than less poetic metaphors. Our research sheds new light on studies of the use of metaphor, which is one of the most basic human cognitive abilities.

  2. Negative magnetic relaxation in superconductors

    Directory of Open Access Journals (Sweden)

    Krasnoperov E.P.


    Full Text Available It was observed that the trapped magnetic moment of HTS tablets or annuli increases in time (negative relaxation if they are not completely magnetized by a pulsed magnetic field. It is shown, in the framework of the Bean critical-state model, that the radial temperature gradient appearing in tablets or annuli during a pulsed field magnetization can explain the negative magnetic relaxation in the superconductor.

  3. Use of Negation in Search (United States)


    as of May 2010, produced a large number of images of Volkswagen Beetles as shown in Figure 8. After indicating they were ready to proceed... Volkswagen 1 beetle -VW -car 1 beetle –car - Volkswagen 1 beetle -VW - Volkswagen 1 beetle -VW -car - Volkswagen 1 black beetle Not within first 30...that had many Volkswagen Beetles in the results, why did you choose not to use negation?] 9. [Do you think that negation would have been useful in

  4. Negative Attitudes, Networks and Education

    DEFF Research Database (Denmark)

    Bennett, Patrick; la Cour, Lisbeth; Larsen, Birthe

    This paper theoretically and empirically assesses the potential explanations behind the educational gap between young natives and immigrants using two measures, negative attitudes towards immigrants and networking. The paper considers that two these parameters may influence high and uneducated...... workers as well as immigrants and natives differently, creating different incentives to acquire education for the two groups. Using rich Danish administrative data, this paper finds suggestive evidence rejecting the theoretical case where negative attitudes decrease 1st generation immigrant education...

  5. Progress in deep-UV photoresists

    Indian Academy of Sciences (India)


    Lithographic processes have been leading the way to miniaturization in semiconductor technology. Any litho- graphic process is characterized by its power (resolution) to resolve the smallest dimension. Grossly, the minimum resolution achievable with a lithography tool is a function of the exposure wavelength and ...

  6. Elimination of photoresist linewidth slimming by fluorination (United States)

    Garza, Cesar M.; Conley, Willard E.


    Typically resist performance has lagged behind exposure tools as new, shorter wavelengths are introduced in the never-ending industry quest to print smaller features. Over time, however, the performance improves until it matches or exceeds that of the resists used in the previous wavelength node; 193 nm resists have not been the exception. Their resolution and stability has improved but one issue that remains is linewidth slimming. This phenomenon consists in a reduction of resist features when they are exposed to an electron beam in an scanning electron microscope during linewidth metrology. Although this phenomenon has been well described and reasonably well understood, no solution exists to eliminate this problem. In this paper we show linewidth slimming can be significantly reduced by fluorinating the resist after the relief image has been developed, keeping the lithographic dimensions unchanged.

  7. The negation bias: When negations signal stereotypic expectancies

    NARCIS (Netherlands)

    Beukeboom, C.J.; Finkenauer, C.; Wigboldus, D.H.J.


    Research on linguistic biases shows that stereotypic expectancies are implicitly reflected in language and are thereby subtly communicated to message recipients. We examined whether these findings extend to the use of negations (e.g., not smart instead of stupid). We hypothesized that people use

  8. Ultrasonic metamaterials with negative modulus. (United States)

    Fang, Nicholas; Xi, Dongjuan; Xu, Jianyi; Ambati, Muralidhar; Srituravanich, Werayut; Sun, Cheng; Zhang, Xiang


    The emergence of artificially designed subwavelength electromagnetic materials, denoted metamaterials, has significantly broadened the range of material responses found in nature. However, the acoustic analogue to electromagnetic metamaterials has, so far, not been investigated. We report a new class of ultrasonic metamaterials consisting of an array of subwavelength Helmholtz resonators with designed acoustic inductance and capacitance. These materials have an effective dynamic modulus with negative values near the resonance frequency. As a result, these ultrasonic metamaterials can convey acoustic waves with a group velocity antiparallel to phase velocity, as observed experimentally. On the basis of homogenized-media theory, we calculated the dispersion and transmission, which agrees well with experiments near 30 kHz. As the negative dynamic modulus leads to a richness of surface states with very large wavevectors, this new class of acoustic metamaterials may offer interesting applications, such as acoustic negative refraction and superlensing below the diffraction limit.

  9. Sigma Models with Negative Curvature

    CERN Document Server

    Alonso, Rodrigo; Manohar, Aneesh V.


    We construct Higgs Effective Field Theory (HEFT) based on the scalar manifold H^n, which is a hyperbolic space of constant negative curvature. The Lagrangian has a non-compact O(n,1) global symmetry group, but it gives a unitary theory as long as only a compact subgroup of the global symmetry is gauged. Whether the HEFT manifold has positive or negative curvature can be tested by measuring the S-parameter, and the cross sections for longitudinal gauge boson and Higgs boson scattering, since the curvature (including its sign) determines deviations from Standard Model values.

  10. Incisional Negative Pressure Wound Therapy

    DEFF Research Database (Denmark)

    Hyldig, Nana; Birke-Sorensen, Hanne; Kruse, Marie

    Aim: Postoperative wound complications make many surgical procedures unnecessarily complex, particularly in high-risk patients. Negative Pressure Wound Therapy is well recognized in the management of open wounds. In recent years, it has been introduced as well in the management of closed surgical...... incisions to reduce postoperative wound complications, though the evidence base to support this intervention is limited. The aim of this study was to assess if Negative Pressure Wound Therapy (NPWT) reduces postoperative complications when applied on closed surgical incisions. Method: A systematic review...

  11. Nanoporous Silica Templated HeteroEpitaxy: Final LDRD Report.

    Energy Technology Data Exchange (ETDEWEB)

    Burckel, David Bruce; Koleske, Daniel; Rowen, Adam M.; Williams, John Dalton; Fan, Hongyou; Arrington, Christian Lew


    This one-year out-of-the-box LDRD was focused on exploring the use of porous growth masks as a method for defect reduction during heteroepitaxial crystal growth. Initially our goal was to investigate porous silica as a growth mask, however, we expanded the scope of the research to include several other porous growth masks on various size scales, including mesoporous carbon, and the UV curable epoxy, SU-8. Use of SU-8 as a growth mask represents a new direction, unique in the extensive literature of patterned epitaxial growth, and presents the possibility of providing a single step growth mask. Additional research included investigation of pore viability via electrochemical deposition into high aspect ratio photoresist patterns and pilot work on using SU-8 as a DUV negative resist, another significant potential result. While the late start nature of this project pushed some of the initial research goals out of the time table, significant progress was made. 3 Acknowledgements This work was performed in part at the Nanoscience @ UNM facility, a member of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation (Grant ECS 03-35765). Sandia is multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United Stated Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported under the Sandia LDRD program (Project 99405). 4

  12. Incisional Negative Pressure Wound Therapy

    DEFF Research Database (Denmark)

    Hyldig, Nana; Vinter, Christina Anne; Bille, Camilla

    Background: Obese women undergoing caesarean section are at increased risk of surgical wound complications, which may lead to delayed recovery, pain, reduced quality of life, and increased health care cost. The aim of this study is to evaluate the effect of incisional Negative Pressure Wound...


    NARCIS (Netherlands)



    Implantation of a negative power intraocular lens is one of the options for surgical correction of high myopia. We studied 36 eyes with a Fechner Worst Claw Lens, implanted in Groningen between March 1987 and November 1991. The preoperative myopia ranged from -7.00 to -30.00 diopters. Twentyone eyes

  14. Counterfactual success and negative freedom

    NARCIS (Netherlands)

    Dowding, K; van Hees, M.V.B.P.M

    Recent theories of negative freedom see it as a value-neutral concept; the definition of freedom should not be in terms of specific moral values. Specifically, preferences or desires do not enter into the definition of freedom. If preferences should so enter then Berlin's problem that a person may

  15. A Semantic Analysis of Negative Concord

    NARCIS (Netherlands)

    Wouden van der, Ton; Zwarts, Frans


    It is not uncommon in natural languages that negation seems to behave in an illogical manner. The general term for the many cases where multiple occurrences of morphologically negative constituents express a single semantic negation is negative concord (Labov 1979). Negative concord may take either

  16. Negation switching invariant signed graphs

    Directory of Open Access Journals (Sweden)

    Deepa Sinha


    Full Text Available A signed graph (or, $sigraph$ in short is a graph G in which each edge x carries a value $\\sigma(x \\in \\{-, +\\}$ called its sign. Given a sigraph S, the negation $\\eta(S$ of the sigraph S is a sigraph obtained from S by reversing the sign of every edge of S. Two sigraphs $S_{1}$ and $S_{2}$ on the same underlying graph are switching equivalent if it is possible to assign signs `+' (`plus' or `-' (`minus' to vertices of $S_{1}$ such that by reversing the sign of each of its edges that has received opposite signs at its ends, one obtains $S_{2}$. In this paper, we characterize sigraphs which are negation switching invariant and also see for what sigraphs, S and $\\eta (S$ are signed isomorphic.

  17. Incisional Negative Pressure Wound Therapy

    DEFF Research Database (Denmark)

    Hyldig, Nana

    the rate of surgical wound infection and wound exudate post-caesarean and that wound infection had a negative impact on quality of life one month after surgery. Alongside the clinical trial, a trial-based cost-effectiveness analysis demonstrated that the treatment is cost-effective in a high......Women with a pre-gestational body mass index (BMI) above 30 kg/m2 giving birth by caesarean section are at high risk of surgical wound infection compared with women with a BMI below 30 kg/m2. Incisional Negative Pressure Wound Therapy (iNPWT) is one strategy to reduce the rate of surgical wound...... infection. However, the treatment is relatively costly compared to standard postoperative dressings and thus it was important to consider the rationale for using iNPWT before introducing the treatment in a clinical setting. This thesis assesses the current evidence of whether iNPWT reduces post...

  18. Proclus’ View about Negative Theology

    Directory of Open Access Journals (Sweden)

    S Rahimiyan


    Full Text Available Negative theology is a modern theological approach that idiomatically implies those theological doctrines which are based on the negative premises and concepts for describing God. Among Greeks, this approach was on its climax in Neo-Platonism. Proclus is one of the Neo-Platonists who lived in fifth century (A.D and was in charge of Athena academy for years. He was the most important Neo-Platonist after Plotinus. In his philosophical system, on the one hand, it is impossible to recognize the first source and, on the other hand, the existence of some principles like the relationship between the creator and the universe, reversion and the way of emanation receiving, requires the knowledge of the first source. It seems that such paradox can be resolved by separating the stages of existence order.

  19. Gram-Negative Flagella Glycosylation

    Directory of Open Access Journals (Sweden)

    Susana Merino


    Full Text Available Protein glycosylation had been considered as an eccentricity of a few bacteria. However, through advances in analytical methods and genome sequencing, it is now established that bacteria possess both N-linked and O-linked glycosylation pathways. Both glycosylation pathways can modify multiple proteins, flagellins from Archaea and Eubacteria being one of these. Flagella O-glycosylation has been demonstrated in many polar flagellins from Gram-negative bacteria and in only the Gram-positive genera Clostridium and Listeria. Furthermore, O-glycosylation has also been demonstrated in a limited number of lateral flagellins. In this work, we revised the current advances in flagellar glycosylation from Gram-negative bacteria, focusing on the structural diversity of glycans, the O-linked pathway and the biological function of flagella glycosylation.

  20. Triple-negative breast cancer


    Chacón, Reinaldo D; Costanzo, María V


    Perou's molecular classification defines tumors that neither express hormone receptors nor overexpress HER2 as triple-negative (TN) tumors. These tumors account for approximately 15% of breast cancers. The so-called basaloid tumors are not always synonymous with TN tumors; they differ in the fact that they express different molecular markers, have a higher histologic grade, and have a worse prognosis. Clinically they occur in younger women as interval cancer, and the risk of recurrence is hig...

  1. Research priorities for negative emissions (United States)

    Fuss, S.; Jones, C. D.; Kraxner, F.; Peters, G. P.; Smith, P.; Tavoni, M.; van Vuuren, D. P.; Canadell, J. G.; Jackson, R. B.; Milne, J.; Moreira, J. R.; Nakicenovic, N.; Sharifi, A.; Yamagata, Y.


    Carbon dioxide removal from the atmosphere (CDR)—also known as ‘negative emissions’—features prominently in most 2 °C scenarios and has been under increased scrutiny by scientists, citizens, and policymakers. Critics argue that ‘negative emission technologies’ (NETs) are insufficiently mature to rely on them for climate stabilization. Some even argue that 2 °C is no longer feasible or might have unacceptable social and environmental costs. Nonetheless, the Paris Agreement endorsed an aspirational goal of limiting global warming to even lower levels, arguing that climate impacts—especially for vulnerable nations such as small island states—will be unacceptably severe in a 2 °C world. While there are few pathways to 2 °C that do not rely on negative emissions, 1.5 °C scenarios are barely conceivable without them. Building on previous assessments of NETs, we identify some urgent research needs to provide a more complete picture for reaching ambitious climate targets, and the role that NETs can play in reaching them.

  2. Dielectric properties of ligand-modified gold nanoparticles/SU-8 photopolymer based nanocomposites

    KAUST Repository

    Toor, Anju


    This article reports the enhanced dielectric properties of a photodefinable nanocomposite material containing sub–10 nm coated metal nanoparticles (NPs). The surface morphology of the synthesized dodecanethiol-functionalized gold NPs was characterized using the transmission electron microscopy (TEM). We investigated the particle agglomeration and dispersion during the various stages of the nanocomposite synthesis using TEM. Physical properties such as dielectric permittivity and dielectric loss were measured experimentally. The dependence of dielectric permittivity and loss tangent on particle concentration and frequency was studied. Nanocomposite films showed an approximately three times enhancement in average dielectric constant over the polymer base value and an average dielectric loss of 0.09 at 1 kHz, at a filler loading of 10% w/w.

  3. Dielectric properties of ligand-modified gold nanoparticle/SU-8 photopolymer based nanocomposites (United States)

    Toor, Anju; So, Hongyun; Pisano, Albert P.


    This article reports the enhanced dielectric properties of a photodefinable polymer nanocomposite material containing sub-10 nm coated metal nanoparticles (NPs). The surface morphology of the synthesized dodecanethiol-functionalized gold NPs was characterized using the transmission electron microscopy (TEM). We investigated the particle agglomeration and dispersion during the various stages of the nanocomposite synthesis using TEM. Physical properties such as dielectric permittivity and dielectric loss were measured experimentally. The dependence of the dielectric permittivity and loss tangent on the particle concentration, and frequency was studied. Nanocomposite films showed an approximately three times enhancement in average dielectric constant over the polymer base value and an average dielectric loss of 0.09 at 1 kHz, at a filler loading of 10% w/w.

  4. Temperature effects in Au piezoresistors integrated in SU-8 cantilever chips

    DEFF Research Database (Denmark)

    Johansson, Alicia; Hansen, Ole; Hales, Jan Harry


    to binding of biomolecules on the surface of the cantilever. Here we present the characterization of the chip with respect to temperature changes in the surrounding environment. Furthermore, self-heating of the piezoresistors due to the applied voltage over the resistors is investigated including...

  5. A Multimodal, SU-8 - Platinum - Polyimide Microelectrode Array for Chronic In Vivo Neurophysiology.

    Directory of Open Access Journals (Sweden)

    Gergely Márton

    Full Text Available Utilization of polymers as insulator and bulk materials of microelectrode arrays (MEAs makes the realization of flexible, biocompatible sensors possible, which are suitable for various neurophysiological experiments such as in vivo detection of local field potential changes on the surface of the neocortex or unit activities within the brain tissue. In this paper the microfabrication of a novel, all-flexible, polymer-based MEA is presented. The device consists of a three dimensional sensor configuration with an implantable depth electrode array and brain surface electrodes, allowing the recording of electrocorticographic (ECoG signals with laminar ones, simultaneously. In vivo recordings were performed in anesthetized rat brain to test the functionality of the device under both acute and chronic conditions. The ECoG electrodes recorded slow-wave thalamocortical oscillations, while the implanted component provided high quality depth recordings. The implants remained viable for detecting action potentials of individual neurons for at least 15 weeks.

  6. Superluminal travel requires negative energies


    Olum, Ken D.


    I investigate the relationship between faster-than-light travel and weak-energy-condition violation, i.e., negative energy densities. In a general spacetime it is difficult to define faster-than-light travel, and I give an example of a metric which appears to allow superluminal travel, but in fact is just flat space. To avoid such difficulties, I propose a definition of superluminal travel which requires that the path to be traveled reach a destination surface at an earlier time than any neig...

  7. Some Phenomena on Negative Inversion Constructions (United States)

    Sung, Tae-Soo


    We examine the characteristics of NDI (negative degree inversion) and its relation with other inversion phenomena such as SVI (subject-verb inversion) and SAI (subject-auxiliary inversion). The negative element in the NDI construction may be" not," a negative adverbial, or a negative verb. In this respect, NDI has similar licensing…

  8. Mondialization: The negation of territory

    Directory of Open Access Journals (Sweden)

    Đorđević Dejan


    Full Text Available The main objective of this paper is to present some weaknesses and inconsistence of the mondialization/globalization concept, especially regarding obvious negation of territoriality as a principle and a crude reality of uneven spatial distribution of resources, wealth and population on global scale. The domination of the globalism and neo-liberalism in the spheres of economy, society, culture and even language leads toward greater differences, in such intensity that some authors describe it as a "clash of civilizations". Loosing territoriality means loosing "raison d’etre" of spatial planning. Some efforts to introduce participation as a planning solution for the beginning of the new century is actually a Trojan horse and a step in the wrong direction.

  9. Congenital nystagmus and negative electroretinography

    Directory of Open Access Journals (Sweden)

    Roussi M


    Full Text Available Mirella Roussi, Hélène Dalens, Jean Jacques Marcellier, Franck BacinDepartment of Ophthalmology, Clermont-Ferrand University, Clermont-Ferrand, FranceAbstract: Congenital nystagmus is a pathologic oculomotor state appearing at about three to four months of age. The precise diagnosis requires detailed clinical examination and electrophysiological findings. This case report presents two male patients with congenital nystagmus examined longitudinally from the age of six months until 17-18 years of age. Clinical and electrophysiological protocols were detailed. The first results showed electronegative electroretinography in the two cases and examination combined with electroretinographic findings helped us to make the diagnosis of Congenital Night Stationary Blindness (CSNB. This diagnosis was confirmed by genetic studies. CSNB is interesting to study because through electrophysiological findings, it enables a better understanding of the physiology of neural transmission in the outer part of the retina.Keywords: Congenital nystagmus, negative electroretinography, congenital night stationary blindness



    Liu, Bingwen; Rieck, Daniel; Van Wie, Bernard J.; Cheng, Gary J.; Moffett, David F.; Kidwell, David A.


    This paper presents a novel method for making micron-sized apertures with tapered sidewalls and nano-sized apertures. Their use in bilayer lipid membrane-based ion selective electrode design is demonstrated and compared to mesoscale bilayers and traditional PVC ion selective electrodes. Micron-sized apertures are fabricated in SU-8 photoresist films and vary in diameter from 10 to 40 microns. The tapered edges in SU-8 films are desired to enhance bilayer lipid membrane (BLM) formation and are...

  11. Pyrolytic 3D Carbon Microelectrodes for Electrochemistry

    DEFF Research Database (Denmark)

    Hemanth, Suhith; Caviglia, Claudia; Amato, Letizia


    electrochemical activity, chemical stability, and ease in surface functionalization [1]. The most common carbon microfabrication techniques (i.e. screen printing) produce two-dimensional (2D) electrodes, which limit the detection sensitivity. Hence several 3D microfabrication techniques have been explored......This work presents the fabrication and characterization of multi-layered three-dimensional (3D) pyrolysed carbon microelectrodes for electrochemical applications. For this purpose, an optimized UV photolithography and pyrolysis process with the negative tone photoresist SU-8 has been developed....... The fabricated three electrode electrochemical cell is characterized with cyclic voltammetry (CV) using the standard potassium ferri-ferrocyanide redox probe. Carbon materials have several attractive characteristics as microelectrodes for electrochemical applications, such as wide potential window, good...

  12. Impedance Characterization of the Degradation of Insulating Layer Patterned on Interdigitated Microelectrode. (United States)

    Lee, Gihyun; Kim, Sohee; Cho, Sungbo


    Life-time and functionality of planar microelectrode-based devices are determined by not only the corrosion-resistance of the electrode, but also the durability of the insulation layer coated on the transmission lines. Degradation of the insulating layer exposed to a humid environment or solution may cause leakage current or signal loss, and a decrease in measurement sensitivity. In this study, degradation of SU-8, an epoxy-based negative photoresist and insulating material, patterned on Au interdigitated microelectrode (IDE) for long-term (>30 days) immersion in an electrolyte at 37 °C was investigated by electrical impedance spectroscopy and theoretical equivalent circuit modeling. From the experiment and simulation results, it was found that the degradation level of the insulating layer of the IDE electrode can be characterized by monitoring the resistance of the insulating layer among the circuit parameters of the designed equivalent circuit modeling.

  13. Microfluidic sensors based on perforated cantilevers

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole

    Arbejdet presenteret i denne PhD afhandling omhandler udviklingen af en mikrofluide sensor basered på bjælke teknologi. Bjælkerne er fremstillet i den negative photo-resist SU-8 og i SiN. I bjælkerne er der inkorporeret et array af huller. To nye sensorer er udviklet på baggrund af de perforerede...... sensor karakteristik ved svage strømninger, som typisk findes i mikrofluide systemer. Enkelte mikro partikler kan måles og filtreres fra en opløsning på engang. Yderligere optimering af partikel filtret vil medfører en signifikant forbedring i forhold til eksisterende partikel filtrer....

  14. Hybrid Microfluidic Platform for Multifactorial Analysis Based on Electrical Impedance, Refractometry, Optical Absorption and Fluorescence

    Directory of Open Access Journals (Sweden)

    Fábio M. Pereira


    Full Text Available This paper describes the development of a novel microfluidic platform for multifactorial analysis integrating four label-free detection methods: electrical impedance, refractometry, optical absorption and fluorescence. We present the rationale for the design and the details of the microfabrication of this multifactorial hybrid microfluidic chip. The structure of the platform consists of a three-dimensionally patterned polydimethylsiloxane top part attached to a bottom SU-8 epoxy-based negative photoresist part, where microelectrodes and optical fibers are incorporated to enable impedance and optical analysis. As a proof of concept, the chip functions have been tested and explored, enabling a diversity of applications: (i impedance-based identification of the size of micro beads, as well as counting and distinguishing of erythrocytes by their volume or membrane properties; (ii simultaneous determination of the refractive index and optical absorption properties of solutions; and (iii fluorescence-based bead counting.


    African Journals Online (AJOL)

    NEGATIVE PRESSURE WOUND THERAPY (NPWT) FOR THE MANAGEMENT OF LAPAROSTOMY WOUNDS: ... Negative pressure wound therapy (NPWT) is one of the new additions to the armamentarium of laparostomy wound management to achieve the above (8). ... However, second day post operatively she.

  16. Triple Negative Breast Cancer – An Overview


    Aysola, Kartik; Desai, Akshata; Welch, Crystal; Xu, Jingyao; QIN, YUNLONG; REDDY, VAISHALI; Matthews,Roland; Owens, Charlotte; Okoli, Joel; Beech, Derrick J; Piyathilake, Chandrika J.; Reddy, Shyam P; Rao, Veena N.


    Triple Negative Breast Cancer (TNBC) is a heterogeneous disease that based on immunohistochemistry (IHC) is estrogen receptor (ER) negative, progesterone receptor (PR) negative and human epidermal growth factor receptor 2 (HER2) negative. TNBC is typically observed in young AA women and Hispanic women who carry a mutation in the BRCA1 gene. TNBC is characterized by a distinct molecular profile, aggressive nature and lack of targeted therapies. The purpose of this article is to review the curr...

  17. Reversing a Negative Measurement in Process with Negative Events: A Haunted Negative Measurement and the Bifurcation of Time

    CERN Document Server

    Snyder, D M


    Reversing an ordinary measurement in process (a haunted measurement) is noted and the steps involved in reversing a negative measurement in process (a haunted negative measurement) are described. In order to discuss in a thorough manner reversing an ordinary measurement in process, one has to account for how reversing a negative measurement in process would work for the same experimental setup. The reason it is necessary to know how a negative measurement in process is reversed is because for a given experimental setup there is no physical distinction between reversing a negative measurement in process and reversing an ordinary measurement in process. In the absence of the reversal of a negative measurement in process in the same experimental setup that supports the reversal of an ordinary measurement in process, the possibility exists of which-way information concerning the negative measurement that would render theoretically implausible reversing an ordinary measuremnt in process. The steps in reversing a n...

  18. Emphatic multiple negative expressions in Dutch

    NARCIS (Netherlands)

    Zeijlstra, H.


    Double Negation languages like Dutch and German still exhibit constructions, such as Dutch 'niemand niet' ‘nobody not’ or 'nooit geen' ‘nothing no’, that seem to have a Negative Concord reading. Since these constructions normally have an emphatic reading, they are called Emphatic Multiple Negative

  19. Hyperbolic spaces are of strictly negative type

    DEFF Research Database (Denmark)

    Hjorth, Poul G.; Kokkendorff, Simon L.; Markvorsen, Steen


    We study finite metric spaces with elements picked from, and distances consistent with, ambient Riemannian manifolds. The concepts of negative type and strictly negative type are reviewed, and the conjecture that hyperbolic spaces are of strictly negative type is settled, in the affirmative...

  20. Low-noise polymeric nanomechanical biosensors

    DEFF Research Database (Denmark)

    Calleja, M.; Tamayo, J.; Nordström, Maria


    A sensor device based on a single polymer cantilever and optical readout has been developed for detection of molecular recognition reactions without the need of a reference cantilever for subtraction of unspecific signals. Microcantilevers have been fabricated in the photoresist SU-8 with one sur...

  1. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science. S KAUSHIK. Articles written in Bulletin of Materials Science. Volume 40 Issue 3 June 2017 pp 435-439. SU-8 photoresist-derived electrospun carbon nanofibres as high-capacity anode material for lithium ion battery · M KAKUNURI S KAUSHIK A SAINI C S SHARMA.

  2. Surface Functionalization of Epoxy-Resist- Based Microcantilevers with Iron Oxide Nanocrystals

    DEFF Research Database (Denmark)

    Ingrosso, Chiara; Sardella, E.; Keller, Stephan Sylvest


    A functionalization procedure is integrated in the fabrication of micromechanical SU-8 cantilevers in order to chemically bind organic-capped Fe2O3 NCs at the photoresist surface, under visible light, ambient atmosp here and room temperature. The achieved highly interconnected NC multilayer netwo...... is demonstrated an active layer for real-time detection of acetone vapor molecules....

  3. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science. A SAINI. Articles written in Bulletin of Materials Science. Volume 40 Issue 3 June 2017 pp 435-439. SU-8 photoresist-derived electrospun carbon nanofibres as high-capacity anode material for lithium ion battery · M KAKUNURI S KAUSHIK A SAINI C S SHARMA · More Details ...

  4. On multiphase negative flash for ideal solutions

    DEFF Research Database (Denmark)

    Yan, Wei; Stenby, Erling Halfdan


    There is a recent interest to solve multiphase negative flash problems where the phase amounts can be negative for normal positive feed composition. Solving such a negative flash problem using successive substitution needs an inner loop for phase distribution calculation at constant fugacity...... coefficients. It is shown that this inner loop, named here as multiphase negative flash for ideal solutions, can be solved either by Michelsen's algorithm for multiphase normal flash, or by its variation which uses F−1 phase amounts as independent variables. In either case, the resulting algorithm is actually...... simpler than the corresponding normal flash algorithm. Unlike normal flash, multiphase negative flash for ideal solutions can diverge if the feasible domain for phase amounts is not closed. This can be judged readily during the iteration process. The algorithm can also be extended to the partial negative...

  5. Negative Pressure Wound Therapy in Maxillofacial Applications

    Directory of Open Access Journals (Sweden)

    Adam J. Mellott


    Full Text Available Negative pressure wound therapy has greatly advanced the field of wound healing for nearly two decades, by providing a robust surgical adjunct technique for accelerating wound closure in acute and chronic wounds. However, the application of negative pressure wound therapy in maxillofacial applications has been relatively under utilized as a result of the physical articulations and contours of the head and neck that make it challenging to obtain an airtight seal for different negative pressure wound therapy systems. Adapting negative pressure wound therapies for maxillofacial applications could yield significant enhancement of wound closure in maxillofacial applications. The current review summarizes the basic science underlying negative pressure wound therapy, as well as specific maxillofacial procedures that could benefit from negative pressure wound therapy.

  6. Zero-truncated negative binomial - Erlang distribution (United States)

    Bodhisuwan, Winai; Pudprommarat, Chookait; Bodhisuwan, Rujira; Saothayanun, Luckhana


    The zero-truncated negative binomial-Erlang distribution is introduced. It is developed from negative binomial-Erlang distribution. In this work, the probability mass function is derived and some properties are included. The parameters of the zero-truncated negative binomial-Erlang distribution are estimated by using the maximum likelihood estimation. Finally, the proposed distribution is applied to real data, the number of methamphetamine in the Bangkok, Thailand. Based on the results, it shows that the zero-truncated negative binomial-Erlang distribution provided a better fit than the zero-truncated Poisson, zero-truncated negative binomial, zero-truncated generalized negative-binomial and zero-truncated Poisson-Lindley distributions for this data.

  7. Adolescents’ Negative Experiences in Organized Youth Activities

    Directory of Open Access Journals (Sweden)

    Jodi Dworkin


    Full Text Available Research indicates that organized youth activities are most often a context of positive development. However, there is a smaller body of evidence suggesting that these activities are sometimes a context of negative experiences that may impede learning or lead to dropping out. To better understand negative experiences in youth activities, we conducted ten focus groups with adolescents. Youths’ descriptions provide an overview of the range of types of negative experiences they encountered, as well as how they responded to them. The most frequent types of negative experiences involved peers and peer group dynamics and aversive behavior attributed to the adult leaders of the activities. The youth described two types of responses to their negative experiences - a passive response of feeling negative emotions, and active coping, which sometimes led to learning.

  8. Analyzing negative ties in social networks

    Directory of Open Access Journals (Sweden)

    Mankirat Kaur


    Full Text Available Online social networks are a source of sharing information and maintaining personal contacts with other people through social interactions and thus forming virtual communities online. Social networks are crowded with positive and negative relations. Positive relations are formed by support, endorsement and friendship and thus, create a network of well-connected users whereas negative relations are a result of opposition, distrust and avoidance creating disconnected networks. Due to increase in illegal activities such as masquerading, conspiring and creating fake profiles on online social networks, exploring and analyzing these negative activities becomes the need of hour. Usually negative ties are treated in same way as positive ties in many theories such as balance theory and blockmodeling analysis. But the standard concepts of social network analysis do not yield same results in respect of each tie. This paper presents a survey on analyzing negative ties in social networks through various types of network analysis techniques that are used for examining ties such as status, centrality and power measures. Due to the difference in characteristics of flow in positive and negative tie networks some of these measures are not applicable on negative ties. This paper also discusses new methods that have been developed specifically for analyzing negative ties such as negative degree, and h∗ measure along with the measures based on mixture of positive and negative ties. The different types of social network analysis approaches have been reviewed and compared to determine the best approach that can appropriately identify the negative ties in online networks. It has been analyzed that only few measures such as Degree and PN centrality are applicable for identifying outsiders in network. For applicability in online networks, the performance of PN measure needs to be verified and further, new measures should be developed based upon negative clique concept.

  9. On the Consumption of Negative Feelings


    Andrade, Eduardo B.; Cohen, Joel B


    How can the hedonistic assumption (i.e., people's willingness to pursue pleasure and avoid pain) be reconciled with people choosing to expose themselves to experiences known to elicit negative feelings? We assess how (1) the intensity of the negative feelings, (2) positive feelings in the aftermath, and (3) the coactivation of positive and negative feelings contribute to our understanding of such behavior. In a series of 4 studies, consumers with either approach or avoidance tendencies (towar...

  10. Art, Terrorism and the Negative Sublime

    Directory of Open Access Journals (Sweden)

    Arnold Berleant


    Full Text Available The range of the aesthetic has expanded to cover not only a wider range of objects and situations of daily life but also to encompass the negative. This includes terrorism, whose aesthetic impact is central to its use as a political tactic. The complex of positive and negative aesthetic values in terrorism are explored, introducing the concept of the sublime as a negative category to illuminate the analysis and the distinctive aesthetic of terrorism.

  11. Exploring Impact: Negative Effects of Social Networks


    Egbert, Henrik; Sedlarski, Teodor


    he sociological literature on social networks emphasizes by and large positive network effects. Negative effects of such networks are discussed rather rarely. This paper tackles negative effects by applying economic theory, particularly neoclassical theory, new institutional theory and the results from experimental economics to the concept of social networks. In the paper it is assumed that social networks are exclusive and since exclusiveness affects the allocation of resources, negative ext...

  12. Negation of resultative and progressive periphrases

    Directory of Open Access Journals (Sweden)

    Raquel González Rodríguez


    Full Text Available This paper focuses on resultative and progressive periphrases in Spanish: and , respectively. These periphrases have been associated with several negated constructions. On the one hand, the negative particle no ‘not’ can precede the auxiliary verb ( and ; on the other hand, we have the structure . Contrary to what has been suggested in the literature, I will show that these negative constructions have a different interpretation and develop a semantic analysis of them. Furthermore, I will offer new evidence in favor of the existence of negative events.

  13. Scope of negation detection in sentiment analysis

    NARCIS (Netherlands)

    Dadvar, M.; Hauff, C.; de Jong, Franciska M.G.


    An important part of information-gathering behaviour has always been to find out what other people think and whether they have favourable (positive) or unfavourable (negative) opinions about the subject. This survey studies the role of negation in an opinion-oriented information-seeking system. We

  14. Appendicitis: A Study of Negative Appendicectomies | Kpolugbo ...

    African Journals Online (AJOL)

    52.8% were confirmed on histology. The diagnostic error (negative appendicectomy) was 47.2%. the error was lower in males (35%) compared with females. The reason for the high negative appendicectomy in women is pelvic inflammatory diseases, which mimics acute appendicitis. Post-operative complications were ...

  15. Negating the Infinitive in Biblical Hebrew

    DEFF Research Database (Denmark)

    Ehrensvärd, Martin Gustaf


    The article examines the negating of the infinitive in biblical and post-biblical Hebrew. The combination of the negation ayin with infinitive is widely claimed to belong to the linguistic layer commonly referred to as late biblical Hebrew and scholars use it to late-date texts. The article showa...

  16. Repetitive negative thinking as a transdiagnostic process

    NARCIS (Netherlands)

    Ehring, T.; Watkins, E.R.


    The current paper provides an updated review of repetitive negative thinking as a transdiagnostic process. It is shown that elevated levels of repetitive negative thinking are present across a large range of Axis I disorders and appear to be causally involved in the maintenance of emotional

  17. Aspects of Negation in Classical Greek. (United States)

    Taylor, Daniel J.


    Traditional grammars are criticized as having obscured or omitted many significant features of negation patterns in classical Greek. The author demonstrates that negation in Greek extensively involves semantic and syntactic factors. Certain of the factors are thoroughly embedded in the traditional approach to grammar, while others are derived from…

  18. Visual content of words delays negation. (United States)

    Orenes, Isabel; Santamaría, Carlos


    Many studies have shown the advantage of processing visualizable words over non-visualizables due to the associated image code. The present paper reports the case of negation in which imagery could slow down processing. Negation reverses the truth value of a proposition from false to true or vice versa. Consequently, negation works only on propositions (reversing their truth value) and cannot apply directly to other forms of knowledge representation such as images (although they can be veridical or not). This leads to a paradoxical hypothesis: despite the advantage of visualizable words for general processing, the negation of clauses containing words related to the representation of an image would be more difficult than negation containing non-visualizable words. Two experiments support this hypothesis by showing that sentences with a previously negated visualizable word took longer to be read than sentences with previously negated non-visualizable words. The results suggest that a verbal code is used to process negation. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Negative Priming in Free Recall Reconsidered (United States)

    Hanczakowski, Maciej; Beaman, C. Philip; Jones, Dylan M.


    Negative priming in free recall is the finding of impaired memory performance when previously ignored auditory distracters become targets of encoding and retrieval. This negative priming has been attributed to an aftereffect of deploying inhibitory mechanisms that serve to suppress auditory distraction and minimize interference with learning and…

  20. Negative appendicectomy: evaluation of ultrasonography and ...

    African Journals Online (AJOL)

    Background: High negative appendicectomy rates are no longer acceptable with improvements in imaging techniques and clinical prediction rules. The use of ultrasound and CT scan in addition to clinical assessment and blood investigations has greatly reduced the negative appendicectomy rate to less than 10%.

  1. Criticism and the Ethics of Negative Reviews (United States)

    Peters, Michael A.


    This paper is an attempt to work through my own angst at a negative review of my "Education, Philosophy and Politics," reviewed recently by Ian Stronach for the "British Educational Research Journal," and to provide a therapeutic reading of the ethics of negative reviews. What of "shots in the dark" and should there…

  2. A Negative Permeability Material at Red Light

    DEFF Research Database (Denmark)

    Yuan, Hsiao-Kuan; Chettiar, Uday K.; Cai, Wenshan


    A negative permeability in a periodic array of pairs of thin silver strips is demonstrated experimentally for two distinct samples. The effect of the strip surface roughness on negative permeability is evaluated. The first sample, Sample A, is fabricated of thinner strips with a root mean square ...

  3. Negative creep in nickel base superalloys

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter; Hald, John


    Negative creep describes the time dependent contraction of a material as opposed to the elongation seen for a material experiencing normal creep behavior. Negative creep occurs because of solid state transformations that results in lattice contractions. For most applications negative creep...... will have no practical implications but under certain conditions it may become critical. For bolts and fasteners, which are highly constrained during service, negative creep may lead to dramatically increased stresses and eventually to failure. The article was inspired by a recent failure of Nimonic 80A...... bolts in German gas turbines. As a result of this failure similar bolts from Danish gas turbines of the same type were investigated and it was found that the bolts had experienced negative creep during service....

  4. Small membranes under negative surface tension. (United States)

    Avital, Yotam Y; Farago, Oded


    We use computer simulations and a simple free energy model to study the response of a bilayer membrane to the application of a negative (compressive) mechanical tension. Such a tension destabilizes the long wavelength undulation modes of giant vesicles, but it can be sustained when small membranes and vesicles are considered. Our negative tension simulation results reveal two regimes-(i) a weak negative tension regime characterized by stretching-dominated elasticity and (ii) a strong negative tension regime featuring bending-dominated elastic behavior. This resembles the findings of the classic Evans and Rawicz micropipette aspiration experiment in giant unilamellar vesicles (GUVs) [E. Evans and W. Rawicz, Phys, Rev. Lett. 64, 2094 (1990)]. However, in GUVs the crossover between the two elasticity regimes occurs at a small positive surface tension, while in smaller membranes it takes place at a moderate negative tension. Another interesting observation concerning the response of a small membrane to negative surface tension is related to the relationship between the mechanical and fluctuation tensions, which are equal to each other for non-negative values. When the tension decreases to negative values, the fluctuation tension γ drops somewhat faster than the mechanical tension τ in the small negative tension regime, before it saturates (and becomes larger than τ) for large negative tensions. The bending modulus exhibits an "opposite" trend. It remains almost unchanged in the stretching-dominated elastic regime, and decreases in the bending-dominated regime. Both the amplitudes of the thermal height undulations and the projected area variations diverge at the onset of mechanical instability.

  5. Negated bio-events: analysis and identification (United States)


    Background Negation occurs frequently in scientific literature, especially in biomedical literature. It has previously been reported that around 13% of sentences found in biomedical research articles contain negation. Historically, the main motivation for identifying negated events has been to ensure their exclusion from lists of extracted interactions. However, recently, there has been a growing interest in negative results, which has resulted in negation detection being identified as a key challenge in biomedical relation extraction. In this article, we focus on the problem of identifying negated bio-events, given gold standard event annotations. Results We have conducted a detailed analysis of three open access bio-event corpora containing negation information (i.e., GENIA Event, BioInfer and BioNLP’09 ST), and have identified the main types of negated bio-events. We have analysed the key aspects of a machine learning solution to the problem of detecting negated events, including selection of negation cues, feature engineering and the choice of learning algorithm. Combining the best solutions for each aspect of the problem, we propose a novel framework for the identification of negated bio-events. We have evaluated our system on each of the three open access corpora mentioned above. The performance of the system significantly surpasses the best results previously reported on the BioNLP’09 ST corpus, and achieves even better results on the GENIA Event and BioInfer corpora, both of which contain more varied and complex events. Conclusions Recently, in the field of biomedical text mining, the development and enhancement of event-based systems has received significant interest. The ability to identify negated events is a key performance element for these systems. We have conducted the first detailed study on the analysis and identification of negated bio-events. Our proposed framework can be integrated with state-of-the-art event extraction systems. The

  6. Information Filtering Based on Users' Negative Opinions (United States)

    Guo, Qiang; Li, Yang; Liu, Jian-Guo


    The process of heat conduction (HC) has recently found application in the information filtering [Zhang et al., Phys. Rev. Lett.99, 154301 (2007)], which is of high diversity but low accuracy. The classical HC model predicts users' potential interested objects based on their interesting objects regardless to the negative opinions. In terms of the users' rating scores, we present an improved user-based HC (UHC) information model by taking into account users' positive and negative opinions. Firstly, the objects rated by users are divided into positive and negative categories, then the predicted interesting and dislike object lists are generated by the UHC model. Finally, the recommendation lists are constructed by filtering out the dislike objects from the interesting lists. By implementing the new model based on nine similarity measures, the experimental results for MovieLens and Netflix datasets show that the new model considering negative opinions could greatly enhance the accuracy, measured by the average ranking score, from 0.049 to 0.036 for Netflix and from 0.1025 to 0.0570 for Movielens dataset, reduced by 26.53% and 44.39%, respectively. Since users prefer to give positive ratings rather than negative ones, the negative opinions contain much more information than the positive ones, the negative opinions, therefore, are very important for understanding users' online collective behaviors and improving the performance of HC model.

  7. Context processing and negative symptoms in schizophrenia. (United States)

    Thoma, Patrizia; Zoppelt, Diana; Wiebel, Burkhard; Daum, Irene


    The objective of the study was to test the assumption that patients with a high level of negative symptoms show disproportionate impairments of inhibition and multitasking, both representing an underlying context processing mechanism. A total of 26 schizophrenia patients scoring high or low on negative symptoms (Positive and Negative Syndrome Scale) and a group of 13 healthy controls were assessed on measures of response inhibition (AX- Continuous Performance Task, Stroop Test) and multitasking (Dual Task, Trail Making Test). Only the high negative symptoms group showed significantly higher inhibition costs and multitasking costs than healthy controls. In the AX-Continuous Performance Test, inhibition costs exceeded context costs in patients with more severe negative symptoms, while in controls a tendency towards the reverse pattern emerged. There were no statistically significant effects involving the patient group with lower negative symptom scores. The pattern of results suggests that primarily patients with more severe negative symptoms have difficulties benefiting from contextual information. The deficit may manifest itself via increased multitasking costs and increased inhibition costs but also via reduced context costs.

  8. Negative HPV screening test predicts low cervical cancer risk better than negative Pap test (United States)

    Based on a study that included more than 1 million women, investigators at NCI have determined that a negative test for HPV infection compared to a negative Pap test provides greater safety, or assurance, against future risk of cervical cancer.

  9. Negative staining and cryo-negative staining of macromolecules and viruses for TEM. (United States)

    De Carlo, Sacha; Harris, J Robin


    In this review we cover the technical background to negative staining of biomolecules and viruses, and then expand upon the different possibilities and limitations. Topics range from conventional air-dry negative staining of samples adsorbed to carbon support films, the variant termed the "negative staining-carbon film" technique and negative staining of samples spread across the holes of holey-carbon support films, to a consideration of dynamic/time-dependent negative staining. For each of these approaches examples of attainable data are given. The cryo-negative staining technique for the specimen preparation of frozen-hydrated/vitrified samples is also presented. A detailed protocol to successfully achieve cryo-negative staining with ammonium molybdate is given, as well as examples of data, which support the claim that cryo-negative staining provides a useful approach for the high-resolution study of macromolecular and viral structure. Copyright © 2009 Elsevier Ltd. All rights reserved.

  10. Antimitochondrial antibody-negative primary biliary cirrhosis. (United States)

    Mendes, Flavia; Lindor, Keith D


    There is a subset of patients who have biochemical and histologic features consistent with primary biliary cirrhosis (PBC) who lack antimitochondrial antibodies (AMA). This entity is usually referred to as AMA-negative PBC or alternatively autoimmune cholangitis. Patients who have AMA-negative PBC are believed to have a similar clinical course, response to treatment, and prognosis as their AMA-positive counterparts. As more sensitive and specific serologic tests are developed to detect serum AMA, it is possible we may find that these patients initially believed to be AMA-negative are indeed AMA-positive, suggesting a single disease process.

  11. Does Negative Type Characterize the Round Sphere?

    DEFF Research Database (Denmark)

    Kokkendorff, Simon Lyngby


    We discuss the measure theoretic metric invariants extent, mean distance and symmetry ratio and their relation to the concept of negative type of a metric space. A conjecture stating that a compact Riemannian manifold with symmetry ratio 1 must be a round sphere, was put forward in a previous paper....... We resolve this conjecture in the class of Riemannian symmetric spaces by showing, that a Riemannian manifold with symmetry ratio 1 must be of negative type and that the only compact Riemannian symmetric spaces of negative type are the round spheres....

  12. Finite Metric Spaces of Strictly negative Type

    DEFF Research Database (Denmark)

    Hjorth, Poul G.

    If a finite metric space is of strictly negative type then its transfinite diameter is uniquely realized by an infinite extent (“load vector''). Finite metric spaces that have this property include all trees, and all finite subspaces of Euclidean and Hyperbolic spaces. We prove that if the distance...... matrix of a finite metric space is both hypermetric and regular, then it is of strictly negative type. We show that the strictly negative type finite subspaces of spheres are precisely those which do not contain two pairs of antipodal points....

  13. Perceived Social Competence, Negative Social Interactions, and Negative Cognitive Style Predict Depressive Symptoms during Adolescence (United States)

    Lee, Adabel; Hankin, Benjamin L.; Mermelstein, Robin J.


    The current study examined whether negative interactions with parents and peers would mediate the longitudinal association between perceived social competence and depressive symptoms and whether a negative cognitive style would moderate the longitudinal association between negative interactions with parents and increases in depressive symptoms.…

  14. The Aesthetic Value Embedded in the Negative Number History and the Negative Number Instruction

    Directory of Open Access Journals (Sweden)

    Shu-Chuan Chen


    Full Text Available The purpose of this article is to interpret the meaning and the aesthetics value in the history of negative numbers and the instruction of negative numbers. The argument begins with explaining the reasons why the aesthetic approach can be recommended to inspire the instruction of negative numbers. The aesthetic contents of negative numbers are then analyzed and presented. The author further explicates the beauty embedded in negative numbers can be demonstrated through their developmental history. This article ends up with emphasizing the 4 merits of aesthetic viewpoints in broadening the visions of the negative number instruction; they are as follows: (1 to calm the restlessness of negative number learning; (2 to inspire student to pay more attention to number learning; (3 to better the understanding of negative number algorithm through the aesthetic intuition afforded by two examples of figure images showing that "subtracting a negative number by adding its opposite" and that "the multiplication of two negative numbers being positive"; (4 to assist student in facing and overcoming the problems in learning negative numbers. The teachers are encouraged to facilitate students to embrace the aesthetic value of negative numbers and to tackle students’ problems in advanced mathematics learning by taking into consideration of their cognitive abilities and mathematic performance.

  15. The chameleonic nature of French ni : negative coordination in a negative concord language

    NARCIS (Netherlands)

    Doetjes, Jenny


    The main goal of this paper is to defend the claim that ni, the French counterpart of neither and nor is always a negative conjunction which takes part in the negative concord system of French. The interpretation one seems to get for this negative concord ni varies depending on the environment where

  16. Production of negatively charged radioactive ion beams (United States)

    Liu, Y.; Stracener, D. W.; Stora, T.


    Beams of short-lived radioactive nuclei are needed for frontier experimental research in nuclear structure, reactions, and astrophysics. Negatively charged radioactive ion beams have unique advantages and allow for the use of a tandem accelerator for post-acceleration, which can provide the highest beam quality and continuously variable energies. Negative ion beams can be obtained with high intensity and some unique beam purification techniques based on differences in electronegativity and chemical reactivity can be used to provide beams with high purity. This article describes the production of negative radioactive ion beams at the former holifield radioactive ion beam facility at Oak Ridge National Laboratory and at the CERN ISOLDE facility with emphasis on the development of the negative ion sources employed at these two facilities. ).

  17. Origin of Negative Longitudinal Piezoelectric Effect. (United States)

    Liu, Shi; Cohen, R E


    Piezoelectrics with negative longitudinal piezoelectric coefficients will contract in the direction of an applied electric field. Such piezoelectrics are thought to be rare, but there is no fundamental physics preventing the realization of negative longitudinal piezoelectric effect in a single-phase material. Using first-principles calculations, we demonstrate that several hexagonal ABC ferroelectrics possess significant negative longitudinal piezoelectric effects. The data mining of a first-principles-based database of piezoelectrics reveals that this effect is a general phenomenon. The origin of this unusual piezoelectric response relies on the strong ionic bonds associated with small effective charges and rigid potential energy surfaces. Moreover, ferroelectrics with negative longitudinal piezoelectric coefficients show anomalous pressure-enhanced ferroelectricity. Our results offer design principles to aid the search for new piezoelectrics for novel electromechanical device applications.

  18. Finite Metric Spaces of Strictly Negative Type

    DEFF Research Database (Denmark)

    Hjorth, Poul; Lisonek, P.; Markvorsen, Steen


    We prove that, if a finite metric space is of strictly negative type, then its transfinite diameter is uniquely realized by the infinite extender (load vector). Finite metric spaces that have this property include all spaces on two, three, or four points, all trees, and all finite subspaces...... of Euclidean spaces. We prove that, if the distance matrix is both hypermetric and regular, then it is of strictly negative type. We show that the strictly negative type finite subspaces of spheres are precisely those which do not contain two pairs of antipodal points. In connection with an open problem raised...... by Kelly, we conjecture that all finite subspaces of hyperbolic spaces are hypermetric and regular, and hence of strictly negative type. (C) 1998 Elsevier Science Inc....

  19. Negative pressure pulmonary oedema after septoplasty. (United States)

    García de Hombre, Alina M; Cuffini, Alejandro; Bonadeo, Alejandro


    Negative pressure pulmonary oedema (NPPO) is an anaesthetic complication due to acute obstruction of the upper airway, whose main cause is laryngospasm. The pathophysiology involves a strong negative intrapleural pressure during inspiration against a closed glottis, which triggers excessive pressure in the pulmonary microvasculature. Although its diagnosis can be difficult, its recognition helps to minimise morbidity and mortality. This article presents a case of NPPO due to postextubation laryngospasm. Copyright © 2011 Elsevier España, S.L. All rights reserved.

  20. Optical Negative Refraction in Ferrofluids with Magnetocontrollability (United States)


    Optical Negative Refraction in Ferrofluids with Magnetocontrollability Y. Gao,1,2 J. P. Huang,1,* Y.M. Liu,3 L. Gao,4 K.W. Yu,2 and X. Zhang3...China (Received 5 October 2009; published 20 January 2010) We numerically demonstrate optical negative refraction in ferrofluids containing isotropic...certain soft materials. As a result, we reveal, for the first time, a new class of all-angle broadband optical nega- tive refraction in ferrofluids with

  1. Negative thermal expansion in framework compounds

    Indian Academy of Sciences (India)


    Nov 27, 2015 ... We have studied negative thermal expansion (NTE) compounds with chemi- cal compositions of NX2O8 and NX2O7 (N=Zr, Hf and X=W, Mo, V) and M2O (M=Cu, Ag) using the techniques of inelastic neutron scattering and lattice dynamics. There is a large variation in the negative thermal expansion ...

  2. What makes dreams positive or negative: relations to fundamental dimensions of positive and negative mood. (United States)

    Kallmeyer, R J; Chang, E C


    The present study examined the general emotional content of dreams reported by individuals who typically experience "positive" versus "negative" dreams. Self-reports of the 153 participants indicated that positive versus negative dreamers (ns = 42 and 24, respectively) generally experienced more positive emotions, e.g., joviality, self-assurance, and fewer negative emotions, e.g., fear, sadness. No differences were found in the self-reports of the participants in the experience of surprise, guilt, fatigue, and shyness between the groups, hence, positive and negative dreams do not appear to reflect simply more positive and fewer negative emotions, respectively.

  3. Negation without symbols: the importance of recurrence and context in linguistic negation. (United States)

    Huette, Stephanie; Anderson, Sarah


    A simple recurrent network with a perceptual simulation layer was trained on a corpus of affirmative and negated sentences. Linguistic negation can be encoded by the network via the inclusion (or absence) of features and categories associated with the senses, in one step, without the need for an explicit logical operation or for treating the negating word any differently than any other words. Visualizing negation as a trajectory in perceptual simulation space is explored in detail, and the implications for artificial intelligence, embodied computational models, and more practical implications of everyday use of negations are discussed.

  4. The Interplay Among Children's Negative Family Representations, Visual Processing of Negative Emotions, and Externalizing Symptoms. (United States)

    Davies, Patrick T; Coe, Jesse L; Hentges, Rochelle F; Sturge-Apple, Melissa L; van der Kloet, Erika


    This study examined the transactional interplay among children's negative family representations, visual processing of negative emotions, and externalizing symptoms in a sample of 243 preschool children (Mage  = 4.60 years). Children participated in three annual measurement occasions. Cross-lagged autoregressive models were conducted with multimethod, multi-informant data to identify mediational pathways. Consistent with schema-based top-down models, negative family representations were associated with attention to negative faces in an eye-tracking task and their externalizing symptoms. Children's negative representations of family relationships specifically predicted decreases in their attention to negative emotions, which, in turn, was associated with subsequent increases in their externalizing symptoms. Follow-up analyses indicated that the mediational role of diminished attention to negative emotions was particularly pronounced for angry faces. © 2017 The Authors. Child Development © 2017 Society for Research in Child Development, Inc.

  5. Personality Moderates the Interaction between Positive and Negative Daily Events Predicting Negative Affect and Stress. (United States)

    Longua, Julie; Dehart, Tracy; Tennen, Howard; Armeli, Stephen


    A 30-day diary study examined personality moderators (neuroticism and extraversion) of the interaction between positive and negative daily events predicting daily negative affect and night-time stress. Multilevel analyses revealed positive daily events buffered the effect of negative daily events on negative affect for individuals low in neuroticism and individuals high in extraversion, but not for individuals high in neuroticism or individuals low in extraversion. Positive daily events also buffered the effect of negative daily events on that night's stress, but only for participants low in neuroticism. As such, this research linked today's events to tonight's stressfulness. This study advances our understanding of how neuroticism and extraversion influence within-person associations between positive and negative events predicting negative affect and stress.

  6. Realism’s understanding of negative numbers

    Directory of Open Access Journals (Sweden)

    Bojanić Petar


    Full Text Available Our topic is the understanding of the nature of negative numbers - the entities to which expressions such as ‘-1’ refer. Following Frege, we view positive whole numbers as providing the answer to the question „how many?“ In this light, how are we to view negative numbers? Both positive and negative numbers can be ordered through the relation of larger or smaller. It is then true of all negative numbers that they are entities which are (somehow smaller than zero. For many, this has been understood as an ontological paradox: how can something be „less than nothing?“ Some propose to avoid the paradox by treating negative numbers as mere façons de parler. In this paper, we propose a more realist account, taking as our starting point the thesis that there is at least one familiar type of object, the magnitude of which can be expressed with negative numbers, namely, debt. How can the sense of an expression be ontologically paradoxical, yet the expression itself still plausibly refer to a social object such as a debt? Or, put differently, how is it possible to be, at the same time, a realist in financial theory and a nominalist in mathematical theory? The paper first shows that the paradox arises when the two distinct ways in which negative numbers are connected to real objects are run together. The first of the two refers to debt only, whereas the second could refer to debt, as well as to physical objects. Finally, we claim that a debt is at once a specifically social object and part of reality as described by physics.

  7. [Negative hallucination, self-onsciousness and ageing]. (United States)

    Hazif-Thomas, C; Stephan, F; Walter, M; Thomas, P


    Negative hallucinations are characterized by a defect in perception of an object or a person, or a denial of the existence of their perception. Negative hallucinations create blank spaces, due to both an impossible representation and an incapability of investment in reality. They have a close relationship with Cotard's syndrome, delusional theme of organ denial observed in melancholic syndromes in the elderly. Phenomenological approach. The phenomenology of negative hallucinations provides quite an amount of information on the origin of the psychotic symptoms when one is rather old. The connections between hallucinations, mood disorders and negative symptoms are often difficult to live with for the nearest and dearest. Negative hallucinations require a strict approach to identify their expression that is crucial because a wide heterogeneity exists within the pathological pictures, as in Cotard's syndrome. Although the negative hallucination has an anti traumatic function in elderly people fighting against mental pain, it still represents a deficiency in symbolization. The prevalence of this symptom is without doubt underestimated, although its presence often underlines thymic suffering that is more striking. These hallucinatory symptoms have an important impact on the patients' daily life, and they appear to be prisoners of a suffering, which cannot be revealed. We propose in this article to review the clinical symptoms of negative hallucinations in the elderly and the way to manage them. The medicinal approaches are not always effective. A greater place must be given to what is in connection with the body, aiming at a strong impact and thus to offer non-pharmacological approaches, such as somatic ones, which can be either invasive (electroconvulsive therapy) or not (transcranial magnetic stimulation). Copyright © 2014. Published by Elsevier Masson SAS.

  8. Detecting negative ions on board small satellites (United States)

    Lepri, S. T.; Raines, J. M.; Gilbert, J. A.; Cutler, J.; Panning, M.; Zurbuchen, T. H.


    Recent measurements near comets, planets, and their satellites have shown that heavy ions, energetic neutral atoms, molecular ions, and charged dust contain a wealth of information about the origin, evolution, and interaction of celestial bodies with their space environment. Using highly sensitive plasma instruments, positively charged heavy ions have been used to trace exospheric and surface composition of comets, planets, and satellites as well as the composition of interplanetary and interstellar dust. While positive ions dominate throughout the heliosphere, negative ions are also produced from surface interactions. In fact, laboratory experiments have shown that oxygen released from rocky surfaces is mostly negatively charged. Negative ions and negatively charged nanograins have been detected with plasma electron analyzers in several different environments (e.g., by Cassini and Rosetta), though more extensive studies have been challenging without instrumentation dedicated to negative ions. We discuss an adaptation of the Fast Imaging Plasma Spectrometer (FIPS) flown on MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) for the measurement of negatively charged particles. MESSENGER/FIPS successfully measured the plasma environment of Mercury from 2011 until 2015, when the mission ended, and has been used to map multiple ion species (H+ through Na+ and beyond) throughout Mercury's space environment. Modifications to the existing instrument design fits within a 3U CubeSat volume and would provide a low mass, low power instrument, ideal for future CubeSat or distributed sensor missions seeking, for the first time, to characterize the contribution of negative particles in the heliospheric plasmas near the planets, moons, comets, and other sources.

  9. [Mutual inhibition between positive and negative emotions]. (United States)

    Shimokawa, A


    The purpose of this study is to examine the relationship between positive and negative emotions. In study 1, 62 emotional items were selected in order to measure subjective emotional experiences. In study 2, comics, photos and poems were randomly presented to 1,220 college students to induce emotion. Subjects were asked to rate their momentary emotional intensity on two set of 5-point scales (general emotional intensity scale and 62 specific emotional intensity scale). In analysis 1, positive correlations were suggested between general emotional intensity scale and some of the specific emotional intensity scales which were activated by stimuli. In analysis 2, 10 positive and 10 negative emotional items were extracted from 62 items by factor analysis. In analysis 3, 4 and 5, it became clear that the distribution of frequency of correlations of 10 positive x 10 negative items changed according to the general emotional intensity scale. That is, from low to moderate levels of GEIS, the two kinds of emotion had no or slightly positive correlation, but at high level they became to be negatively correlated. From the facts described above, it is concluded that positive and negative emotions is not always independent, but show mutual inhibition in case of high intensity level of one of each emotions.

  10. Negative obstacle detection by thermal signature (United States)

    Matthies, Larry; Rankin, A.


    Detecting negative obstacles (ditches, potholes, and other depressions) is one of the most difficult problems in perception for autonomous, off-road navigation. Past work has largely relied on range imagery, because that is based on the geometry of the obstacle, is largely insensitive to illumination variables, and because there have not been other reliable alternatives. However, the visible aspect of negative obstacles shrinks rapidly with range, making them impossible to detect in time to avoid them at high speed. To relive this problem, we show that the interiors of negative obstacles generally remain warmer than the surrounding terrain throughout the night, making thermal signature a stable property for night-time negative obstacle detection. Experimental results to date have achieved detection distances 45% greater by using thermal signature than by using range data alone. Thermal signature is the first known observable with potential to reveal a deep negative obstacle without actually seeing far into it. Modeling solar illumination has potential to extend the usefulness of thermal signature through daylight hours.

  11. Exclusion of identification by negative superposition

    Directory of Open Access Journals (Sweden)

    Takač Šandor


    Full Text Available The paper represents the first report of negative superposition in our country. Photo of randomly selected young, living woman was superimposed on the previously discovered female skull. Computer program Adobe Photoshop 7.0 was used in work. Digitilized photographs of the skull and face, after uploaded to computer, were superimposed on each other and displayed on the monitor in order to assess their possible similarities or differences. Special attention was payed to matching the same anthropometrical points of the skull and face, as well as following their contours. The process of fitting the skull and the photograph is usually started by setting eyes in correct position relative to the orbits. In this case, lower jaw gonions go beyond the face contour and gnathion is highly placed. By positioning the chin, mouth and nose their correct anatomical position cannot be achieved. All the difficulties associated with the superposition were recorded, with special emphasis on critical evaluation of work results in a negative superposition. Negative superposition has greater probative value (exclusion of identification than positive (possible identification. 100% negative superposition is easily achieved, but 100% positive - almost never. 'Each skull is unique and viewed from different perspectives is always a new challenge'. From this point of view, identification can be negative or of high probability.

  12. Gender differences in negative reinforcement smoking expectancies. (United States)

    Pang, Raina D; Zvolensky, Michael J; Schmidt, Norman B; Leventhal, Adam M


    Previous research suggests that females may be more motivated to smoke for negative reinforcement (NR) than males. However, it remains unclear whether gender differences in smoking outcome expectancies for negative smoking reinforcement-an important theoretical and clinical target defined as beliefs that smoking alleviates negative affect-exist above and beyond gender differences in depression and/or other outcome expectancies. Relations between gender and negative smoking reinforcement expectancies were examined in two independent samples. Sample 1 consisted of non-treatment seeking daily smokers (Male n = 188; Female n = 91) recruited from Southern California (49.5% Black, 32.2% Caucasian, and 18.3% other race/ethnicity). Sample 2 consisted of treatment seeking daily smokers (Male n = 257; Female n = 237) in Northern Florida and Vermont (10.7% Black, 82.9% Caucasian, and 6.4% other). Females (vs. males) reported stronger NR smoking expectancies with and without statistically controlling for nicotine dependence, other smoking expectancies, and anxiety and depression in both samples (βs = .06 to .14, ps = .06 to gender-specific etiological process disproportionately prominent in women. Enhancing ability to cope with negative affect without smoking or challenge NR expectancies may be particularly important for cessation treatment in women. © The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail:

  13. Transformation media with negative refractive indices (United States)

    Chan, C. T.; Lai, Y.; Chen, H. Y.; Ng, Jack; Zhang, Z. Q.


    Artificially structured materials with a negative refractive index designed by transformation optics can have interesting properties. Based on merging the concept of complementary media and transformation media, we propose an invisibility cloak operating at a finite frequency that can make an object invisible with a pre-specified shape and size within a certain distance outside the shell. The cloak is comprised of a dielectric core, a negative index metamaterial shell and an ``anti-object'' embedded inside the shell. The cloaked object is not blinded by the cloaking shell since it lies outside the cloak. Full-wave simulations in two dimensions have been performed to verify the cloaking effect. We also show that a positive index core coated with a negative index shell can result in a frequency selective super-absorber which has an absorption cross section that is significantly higher than the geometric cross section.

  14. Goffman, Parsons, and the Negational Self

    Directory of Open Access Journals (Sweden)

    James J. Chriss


    Full Text Available Erving Goffman’s emphasis on impression management in everyday life means that for the most part persons offer only partial or incomplete glimpses of themselves. Indeed, under specifiable conditions self-presentations may take the form of a negational self. If negational selves exist at the person or individual level, then they must also exist at the collective level (that is, if we are to take seriously such notions as the social mind, collective representations, or even culture. Understandings of how this negational self appears and is produced at various analytical levels (micro, meso, and macro can be anchored via a conceptual schema which merges Goffman’s own identity typology with the three-world model of Jürgen Habermas by way of Talcott Parsons.

  15. [H. pylori-negative gastric cancer]. (United States)

    Kato, Mototsugu; Ono, Shouko; Shimizu, Yuichi; Sakamoto, Naoya; Mabe, Katsuhiro


    Broad category of H. pylori-negative gastric cancer includes true gastric cancer without history of H. pylori infection, gastric cancer after successful eradication of H. pylori, and H. pylori-negative gastric cancer with history of H. pylori infection. The frequency of gastric cancer without history of H. pylori infection was less than 1% in Japan. Although preventive effect for gastric cancer of H. pylori eradication can be expected, risk of gastric cancer incidence continues after eradication of H. pylori. The frequency of gastric cancer after successful eradication has been increasing, since eradication treatment was widely spread in Japan. The features of H. pylori-negative gastric cancer were reported to be different from conventional H. pylori-positive gastric cancer. Endoscopic screening of gastric cancer requires to understand the characteristics of gastric cancer based on status of H. pylori infection.

  16. Animal Reasoning: Negation and Representations of Absence.

    Directory of Open Access Journals (Sweden)

    Morales Ladrón de Guevara, Jorge


    Full Text Available In this paper I reject the possibility that animal reasoning, negation in particular, necessarily involves the representation of Absence, as suggested by José Luis Bermúdez, since this would still work as a logical negation (unavailable for non-linguistic creatures. False belief, pretense, and communication experiments show that non-human animals (at least some primates have difficulties representing absent entities or properties. I offer an alternative account resorting to the sub-symbolic similarity judgments proposed by Vigo & Allen and I introduce the notion of expectation: animal proto-negation takes place through the incompatibility between an expected and the actual representation. Finally, I propose that the paradigm of expectations can be extrapolated to other experiments in cognitive psychology (both with pre-linguistic children and animals in order to design “fair” experiments which test other minds considering their true abilities.

  17. Classical fluids of negative heat capacity

    Energy Technology Data Exchange (ETDEWEB)

    Landsberg, P.T. (Southampton Univ., (United Kingdom). Faculty of Mathematical Studies); Woodard, R.P. (Florida Univ., Gainesville, FL (United States). Dept. of Physics)


    It is shown that new parameters X can be defined such that the heat capacity C{sub X} {equivalent to} T({partial derivative}S/{partial derivative}T)X is negative, even when the canonical ensemble (i.e. at fixed T = ({partial derivative}U/{partial derivative}S) and Y {ne} X) is stable. As examples we treat black body radiation and general gas systems with nonsingular {kappa}{sub T}. For the case of a simple ideal gas we even exhibit an apparatus which enforces a constraint X(p,V) = const. that makes C{sub X} < 0. Since it is possible to invent constraints for which canonically stable systems have negative heat capacity we speculate that it may also be possible to infer the statistical mechanics of canonically unstable systems - for which even the traditional heat capacities are negative - by imposing constraints that stabilize the associated, inoncanonical ensembles.

  18. Classical fluids of negative heat capacity

    Energy Technology Data Exchange (ETDEWEB)

    Landsberg, P.T. [Southampton Univ., (United Kingdom). Faculty of Mathematical Studies; Woodard, R.P. [Florida Univ., Gainesville, FL (United States). Dept. of Physics


    It is shown that new parameters X can be defined such that the heat capacity C{sub X} {equivalent_to} T({partial_derivative}S/{partial_derivative}T)X is negative, even when the canonical ensemble (i.e. at fixed T = ({partial_derivative}U/{partial_derivative}S) and Y {ne} X) is stable. As examples we treat black body radiation and general gas systems with nonsingular {kappa}{sub T}. For the case of a simple ideal gas we even exhibit an apparatus which enforces a constraint X(p,V) = const. that makes C{sub X} < 0. Since it is possible to invent constraints for which canonically stable systems have negative heat capacity we speculate that it may also be possible to infer the statistical mechanics of canonically unstable systems - for which even the traditional heat capacities are negative - by imposing constraints that stabilize the associated, inoncanonical ensembles.

  19. News Media Framing of Negative Campaigning

    DEFF Research Database (Denmark)

    Pedersen, Rasmus Tue


    News media coverage of election campaigns is often characterized by use of the strategic game frame and a focus on politicians’ use of negative campaigning. However, the exact relationship between these two characteristics of news coverage is largely unexplored. This article theorizes that consumer...... demand and norms of journalistic independence might induce the news media outlets to cover negative campaigning with a strategic game frame. A comprehensive content analysis based on several newspaper types, several election campaigns, and several different measurements of media framing confirms...... that news coverage of negative campaigning does apply the strategic game frame to a significantly larger degree than articles covering positive campaigning. This finding has significant implications for campaigning politicians and for scholars studying campaign and media effects....

  20. Emotionally negative pictures enhance gist memory. (United States)

    Bookbinder, S H; Brainerd, C J


    In prior work on how true and false memory are influenced by emotion, valence and arousal have often been conflated. Thus, it is difficult to say which specific effects are caused by valence and which are caused by arousal. In the present research, we used a picture-memory paradigm that allowed emotional valence to be manipulated with arousal held constant. Negatively valenced pictures elevated both true and false memory, relative to positive and neutral pictures. Conjoint recognition modeling revealed that negative valence (a) reduced erroneous suppression of true memories and (b) increased the familiarity of the semantic content of both true and false memories. Overall, negative valence impaired the verbatim side of episodic memory but enhanced the gist side, and these effects persisted even after a week-long delay. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  1. GDC-0941 and Cisplatin in Treating Patients With Androgen Receptor-Negative Triple Negative Metastatic Breast Cancer (United States)


    Estrogen Receptor Negative Breast Cancer; Human Epidermal Growth Factor 2 Negative Carcinoma of Breast; Triple Negative Breast Cancer; Recurrent Breast Cancer; Stage IV Breast Cancer; Triple-negative Breast Cancer

  2. Giant negative thermal expansion in magnetic nanocrystals (United States)

    Zheng, X. G.; Kubozono, H.; Yamada, H.; Kato, K.; Ishiwata, Y.; Xu, C. N.


    Most solids expand when they are heated, but a property known as negative thermal expansion has been observed in a number of materials, including the oxide ZrW2O8 (ref. 1) and the framework material ZnxCd1-x(CN)2 (refs 2,3). This unusual behaviour can be understood in terms of low-energy phonons, while the colossal values of both positive and negative thermal expansion recently observed in another framework material, Ag3[Co(CN)6], have been explained in terms of the geometric flexibility of its metal-cyanide-metal linkages. Thermal expansion can also be stopped in some magnetic transition metal alloys below their magnetic ordering temperature, a phenomenon known as the Invar effect, and the possibility of exploiting materials with tuneable positive or negative thermal expansion in industrial applications has led to intense interest in both the Invar effect and negative thermal expansion. Here we report the results of thermal expansion experiments on three magnetic nanocrystals-CuO, MnF2 and NiO-and find evidence for negative thermal expansion in both CuO and MnF2 below their magnetic ordering temperatures, but not in NiO. Larger particles of CuO and MnF2 also show prominent magnetostriction (that is, they change shape in response to an applied magnetic field), which results in significantly reduced thermal expansion below their magnetic ordering temperatures; this behaviour is not observed in NiO. We propose that the negative thermal expansion effect in CuO (which is four times larger than that observed in ZrW2O8) and MnF2 is a general property of nanoparticles in which there is strong coupling between magnetism and the crystal lattice.

  3. Automatic negation detection in narrative pathology reports. (United States)

    Ou, Ying; Patrick, Jon


    To detect negations of medical entities in free-text pathology reports with different approaches, and evaluate their performances. Three different approaches were applied for negation detection: the lexicon-based approach was a rule-based method, relying on trigger terms and termination clues; the syntax-based approach was also a rule-based method, where the rules and negation patterns were designed using the dependency output from the Stanford parser; the machine-learning-based approach used a support vector machine as a classifier to build models with a number of features. A total of 284 English pathology reports of lymphoma were used for the study. The machine-learning-based approach had the best overall performance on the test set with micro-averaged F-score of 82.56%, while the syntax-based approach performed worst with 78.62% F-score. The lexicon-based approach attained an overall average precision of 89.74% and recall of 76.09%, which were significantly better than the results achieved by Negation Tagger with a similar approach. The lexicon-based approach benefitted from being customized to the corpus more than the other two methods. The errors in negation detection with the syntax-based approach producing poorest performance were mainly due to the poor parsing results, and the errors with the other methods were probably because of the abnormal grammatical structures. A machine-learning-based approach has potential advantages for negation detection, and may be preferable for the task. To improve the overall performance, one of the possible solutions is to apply different approaches to each section in the reports. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Negative electrodes for lithium cells and batteries (United States)

    Vaughey, John T.; Fransson, Linda M.; Thackeray, Michael M.


    A negative electrode is disclosed for a non-aqueous electrochemical cell. The electrode has an intermetallic compound as its basic structural unit with the formula M.sub.2 M' in which M and M' are selected from two or more metal elements including Si, and the M.sub.2 M' structure is a Cu.sub.2 Sb-type structure. Preferably M is Cu, Mn and/or Li, and M' is Sb. Also disclosed is a non-aqueous electrochemical cell having a negative electrode of the type described, an electrolyte and a positive electrode. A plurality of cells may be arranged to form a battery.

  5. Negative Ion Sources: Magnetron and Penning

    CERN Document Server

    Faircloth, D.C.


    The history of the magnetron and Penning electrode geometry is briefly outlined. Plasma generation by electrical discharge-driven electron impact ionization is described and the basic physics of plasma and electrodes relevant to magnetron and Penning discharges are explained. Negative ions and their applications are introduced, along with their production mechanisms. Caesium and surface production of negative ions are detailed. Technical details of how to build magnetron and Penning surface plasma sources are given, along with examples of specific sources from around the world. Failure modes are listed and lifetimes compared.

  6. Indlæring af negative tal


    Damm, Jakob; Krabbe, Elisabeth; Nissen, Rie


    I denne rapport ses på indlæring af negative tal som en case i indlæringsvanskelighederne i matematikundervisningen i 4. – 6. klasse. Problemstillingen belyses fra to vinkler. Der ses på casen fra et historisk perspektiv, hvor der gives en kort introduktion af de negative tals udvikling og plads i historien. Her følger nogle forslag til, hvordan historien kan bruges i undervisningen. Casen belyses også fra et psykologisk perspektiv, hvor Piaget, Vygotsky og Sfards teorier kort introducere...

  7. Soft Manifold Dynamics behind Negative Thermal Expansion (United States)

    Schlesinger, Z.; Rosen, J. A.; Hancock, J. N.; Ramirez, A. P.


    Minimal models are developed to examine the origin of large negative thermal expansion in underconstrained systems. The dynamics of these models reveals how underconstraint can organize a thermodynamically extensive manifold of low-energy modes which not only drives negative thermal expansion but extends across the Brillioun zone. Mixing of twist and translation in the eigenvectors of these modes, for which in ZrW2O8 there is evidence from infrared and neutron scattering measurements, emerges naturally in our model as a signature of the dynamics of underconstraint.

  8. Negative-Index Media for Matter Waves (United States)

    Perales, F.; Bocvarski, V.; Baudon, J.; Hamamda, M.; Grucker, J.; Dutier, G.; Mainos, C.; Boustimi, M.; Ducloy, M.


    One reviews the recently introduced field of matter-wave "meta-optics", i.e. the extension of optical negative-index media (NIM) to atom optics. After emphasizing the differences with light meta-optics and particularly the necessary transient character of NIM's in atom optics, we present the way of generating matter-wave NIM's and their general properties: negative refraction, atom meta-lenses. Finally their specific features are reviewed: longitudinal wave packet narrowing associated to a time-reversal effect, transient revivals of evanescent matter waves and atom reflection echoes at a potential barrier.

  9. Negative thermal expansion in framework compounds

    Indian Academy of Sciences (India)

    electron microscopy, EXAFS and differential scanning calorimetry have been used to study structural properties as a function of temperature for these compounds. In this paper we report the results obtained from our study [14–20] of negative thermal expansion (NTE) compounds with chemical compositions of NX2O8 and.


    African Journals Online (AJOL)


    literature can offer. But not all literary expressions are posers of questions and problems. Certain concepts such as Keats' Negative. Capability suggest solutions to Camus' Sisyphean problem and its ilk. This paper explores this problem-solution relationship and finds complementarity and possibility feasible. Introduction.

  11. Negative Interpersonal Interactions in Student Training Settings (United States)

    Ferris, Patricia A.; Kline, Theresa J. B.


    Studies demonstrate that negative interpersonal interaction(s) (NII) such as bullying are frequent and harmful to individuals in workplace and higher education student settings. Nevertheless, it is unclear whether the degree of perceived severity of NII varies by the status of the actor. The present study explored the moderating effect of actor…

  12. Targeting EGFR in Triple Negative Breast Cancer


    Naoto T. Ueno, Dongwei Zhang


    Our preliminary data show that erlotinib inhibits Triple-negative breast cancer (TNBC) in a xenograft model. However, inhibition of metastasis by erlotinib is accompanied by nonspecific effects because erlotinib can inhibit other kinases; thus, more direct targets that regulate TNBC metastasis need to be identified to improve its therapeutic efficacy.

  13. Targeting EGFR in Triple Negative Breast Cancer

    Directory of Open Access Journals (Sweden)

    Naoto T. Ueno, Dongwei Zhang


    Full Text Available Our preliminary data show that erlotinib inhibits Triple-negative breast cancer (TNBC in a xenograft model. However, inhibition of metastasis by erlotinib is accompanied by nonspecific effects because erlotinib can inhibit other kinases; thus, more direct targets that regulate TNBC metastasis need to be identified to improve its therapeutic efficacy.

  14. Magnetic levitation induced by negative permeability


    Rangelov, A. A.


    In this paper we study the interaction between a point magnetic dipole and a semi-infinite metamaterial using the method of images. We obtain analytical expressions for the levitation force for an arbitrarily oriented dipole. Surprisingly the maximal levitation force for negative permeability is found to be stronger compared to the case when the dipole is above a superconductor.

  15. Negative emotions impact on mental physical health

    Directory of Open Access Journals (Sweden)

    Oblitas, Luis Armando


    Full Text Available Fear, sadness, anger and disgust are considered affective states, that when they become frequent and intense, adversely affect the quality of life. Consequently, negative emotions are regarded as one of the key risk factors in physical and mental illness. Firstly, this article aims to define precisely concepts and key features of each emotion. The second objective of this paper is to show a synthesis of scientific findings supporting the influence of emotional factors, especially classic negative emotions in the process of health and disease. These psychophysiological phenomena have been associated with mental and physical illness as influencing variables in its initiation, development and maintenance. Therefore, the paper reviews some of the links between these four negative emotions and mental disorders. It also reviews the evidence supporting the influence of negative emotions in the development of risk behaviors to physical health. Finally, we describe some data supporting the impact of psychophysiological activation of emotions in organic systems, such as, for instance, immunity, tumor processes and so on

  16. The Contrast Theory of negative input. (United States)

    Saxton, M


    Beliefs about whether or not children receive corrective input for grammatical errors depend crucially on how one defines the concept of correction. Arguably, previous conceptualizations do not provide a viable basis for empirical research (Gold, 1967; Brown & Hanlon, 1970; Hirsh-Pasek, Treiman & Schneiderman, 1984). Within the Contrast Theory of negative input, an alternative definition of negative evidence is offered, based on the idea that the unique discourse structure created in the juxtaposition of child error and adult correct form can reveal to the child the contrast, or conflict, between the two forms, and hence provide a basis for rejecting the erroneous form. A within-subjects experimental design was implemented for 36 children (mean age 5;0), in order to compare the immediate effects of negative evidence with those of positive input, on the acquisition of six novel irregular past tense forms. Children reproduced the correct irregular model more often, and persisted with fewer errors, following negative evidence rather than positive input.

  17. Quantum Heat Engine and Negative Boltzmann Temperature (United States)

    Xi, Jing-Yi; Quan, Hai-Tao


    To clarify the ambiguity on negative Boltzmann temperature in literature, we study the Carnot and the Otto cycle with one of the heat reservoirs at the negative Boltzmann temperature based on a canonical ensemble description. The work extraction, entropy production and the efficiency of these cycles are explored. Conditions for constructing and properties of these thermodynamic cycles are elucidated. We find that the apparent “violation” of the second law of thermodynamics in these cycles are due to the fact that the traditional definition of thermodynamic efficiency is inappropriate in this situation. When properly understanding the efficiency and the adiabatic processes, in which the system crosses over “absolute ZERO” in a limit sense, the Carnot cycle with one of the heat reservoirs at a negative Boltzmann temperature can be understood straightforwardly, and it contradicts neither the second nor the third law of thermodynamics. Hence, negative Boltzmann temperature is a consistent concept in thermodynamics. We use a two-level system and an Ising spin system to illustrate our central results. Support from the National Science Foundation of China under Grants Nos. 11375012, 11534002, and The Recruitment Program of Global Youth Experts of China

  18. Performance characteristics of positive and negative delayed ...

    Indian Academy of Sciences (India)

    Cochin University of Science and Technology, Cochin 682 022, India ... press chaotic dynamics and bistabily in semiconductor lasers [37,38]. The effect of such a combination in inducing chaotic dynamics through a quasiperiodic route in .... To study the effect of both positive- and negative-delayed optoelectronic feedback.

  19. Performance characteristics of positive and negative delayed ...

    Indian Academy of Sciences (India)

    The effects of positive and negative delayed optoelectronic feedback in producing chaotic outputs from such lasers with nonlinear gain reduction in its optimum ... Sophisticated Test and Instrumentation Centre; Cochin University of Science and Technology, Cochin 682 022, India; International School of Photonics, Cochin ...

  20. Error-Related Psychophysiology and Negative Affect (United States)

    Hajcak, G.; McDonald, N.; Simons, R.F.


    The error-related negativity (ERN/Ne) and error positivity (Pe) have been associated with error detection and response monitoring. More recently, heart rate (HR) and skin conductance (SC) have also been shown to be sensitive to the internal detection of errors. An enhanced ERN has consistently been observed in anxious subjects and there is some…

  1. Exploring the Psychological Influence of Perceived Negative ...

    African Journals Online (AJOL)

    This paper critically examined the psychological influence of perceived negative foreign factors which were those obstacles brought to Nigeria and Nigerians since our first contact with the European colonialists. The obstacles have constituted formidable barriers to indigenous organisational performance and national ...

  2. Preservation Copying Endangered Historic Negative Collections

    DEFF Research Database (Denmark)

    Kejser, Ulla Bøgvad


    This article discusses preservation copying of unstable B&W nitrate and acetate still photographic negatives. It focuses on evaluating two different strategies for preserving the copies from a point of view of quality and cost-effectiveness. The evaluated strategies are preservation of the master...

  3. Discriminant projective non-negative matrix factorization.

    Directory of Open Access Journals (Sweden)

    Naiyang Guan

    Full Text Available Projective non-negative matrix factorization (PNMF projects high-dimensional non-negative examples X onto a lower-dimensional subspace spanned by a non-negative basis W and considers W(T X as their coefficients, i.e., X≈WW(T X. Since PNMF learns the natural parts-based representation Wof X, it has been widely used in many fields such as pattern recognition and computer vision. However, PNMF does not perform well in classification tasks because it completely ignores the label information of the dataset. This paper proposes a Discriminant PNMF method (DPNMF to overcome this deficiency. In particular, DPNMF exploits Fisher's criterion to PNMF for utilizing the label information. Similar to PNMF, DPNMF learns a single non-negative basis matrix and needs less computational burden than NMF. In contrast to PNMF, DPNMF maximizes the distance between centers of any two classes of examples meanwhile minimizes the distance between any two examples of the same class in the lower-dimensional subspace and thus has more discriminant power. We develop a multiplicative update rule to solve DPNMF and prove its convergence. Experimental results on four popular face image datasets confirm its effectiveness comparing with the representative NMF and PNMF algorithms.

  4. Monogamy Relations for Squared Entanglement Negativity (United States)

    Liu, Feng


    This paper contains two main contents. In the first part, we provide two counterexamples of monogamy inequalities for the squared entanglement negativity: one three-qutrit pure state which violates of the He—Vidal monogamy conjecture, and one four-qubit pure state which disproves the squared-negativity-based Regula—Martino—Lee—Adesso-class strong monogamy conjecture. In the second part, we investigate the sharing of the entanglement negativity in a composite cavity-reservoir system using the corresponding multipartite entanglement scores, and then we find that there is no simple dominating relation between multipartite entanglement scores and the entanglement negativity in composite cavity-reservoir systems. As a by-product, we further validate that the entanglement of two cavity photons is a decreasing function of the evolution time, and the entanglement will suddenly disappear interacting with independent reservoirs. Supported by the National Natural Science Foundation of China under Grant No. 60973135 and Shandong Provincial Natural Science Foundation of China under Grant No. ZR2015FQ006

  5. Negative Life Events Scale for Students (NLESS) (United States)

    Buri, John R.; Cromett, Cristina E.; Post, Maria C.; Landis, Anna Marie; Alliegro, Marissa C.


    Rationale is presented for the derivation of a new measure of stressful life events for use with students [Negative Life Events Scale for Students (NLESS)]. Ten stressful life events questionnaires were reviewed, and the more than 600 items mentioned in these scales were culled based on the following criteria: (a) only long-term and unpleasant…

  6. On affine non-negative matrix factorization

    DEFF Research Database (Denmark)

    Laurberg, Hans; Hansen, Lars Kai


    We generalize the non-negative matrix factorization (NMF) generative model to incorporate an explicit offset. Multiplicative estimation algorithms are provided for the resulting sparse affine NMF model. We show that the affine model has improved uniqueness properties and leads to more accurate id...

  7. Variations of Negative Pressure Wound Therapy

    African Journals Online (AJOL)

    There have been several reports about the various types of negative pressure wound therapy. (NPWT). The most common dressing material is the polyurethane foam sponge, although there have been some reports that did not use any dressing materials.[1] Even for the polyurethane foam sponges, there are wide variations ...

  8. The negative ions emission in nitrogen (United States)

    Soon, W. H.; Kunc, J. A.


    The contribution of negative atomic ions to continuum radiation in nitrogen plasma is discussed. It is shown that both unstable N(-)(3P) and metastable N(-)(1D) ions have a significant effect on the total production of the continuum radiation at electron temperatures below 12,000 K.

  9. Positive and negative pulsed corona in argon

    NARCIS (Netherlands)

    E.M. van Veldhuizen; W.R. Rutgers; U. Ebert (Ute)


    htmlabstractPhotographs are obtained of corona discharges in argon at atmospheric pressure using a high resolution, intensified CCD camera. Positive and negative polarity is applied at the curved electrode in a point-plane gap and a plane-plane gap with a protruding point. Branching is observed in

  10. Entanglement versus negative domains of Wigner functions

    DEFF Research Database (Denmark)

    Dahl, Jens Peder; Mack, H.; Wolf, A.


    We show that s waves, that is wave functions that only depend on a hyperradius, are entangled if and only if the corresponding Wigner functions exhibit negative domains. We illustrate this feature using a special class of s waves which allows us to perform the calculations analytically. This class...

  11. Negative freedom and the liberal paradoxes

    NARCIS (Netherlands)

    van Hees, M.V.B.P.M

    In their game-theoretic formulations, the liberal paradoxes of Amartya Sm and Alan Gibbard show a tension between freedom on the one hand, and Pareto optimality and stability on the other. This article examines what happens to the liberal paradoxes if a negative conception of freedom is used. Given

  12. Electroluminescence and negative differential resistance studies of ...

    Indian Academy of Sciences (India)

    Negative differential resistance (NDR) characteristics observed at a low voltage region in blended OLED is related to the generation of guest hopping site and phonon scattering phenomenon. However, luminescence of the devices is not altered by the NDR effect. Keywords. Organic-light-emitting diodes; Alq3; TPD; PBD; ...

  13. Electroluminescence and negative differential resistance studies of ...

    Indian Academy of Sciences (India)

    Electroluminescence properties were investigated with respect to blend systems. Significant improvement in turn-on voltage and luminance intensity was observed by employing the blends technique. Negative differential resistance (NDR) characteristics observed at a low voltage region in blended OLED is related to the ...

  14. [Negative symptoms of schizophrenia: historical aspects]. (United States)

    Pringuey, D; Paquin, N; Cherikh, F; Giordana, B; Belzeaux, R; Cermolacce, M; Adida, M; Azorin, J-M


    The history of negative symptoms of schizophrenia rises early days of medicine in clinical and pathophysiological differences between positive and negative and their complex joint. Forming a set of typical core of symptoms, and some feature of a syndrome belonging to a specific pathophysiological mechanism, negative symptoms of schizophrenia emerge from old descriptions of clinical pictures, related to the overall look of madness, the heart of alienation, a central sign of early dementia, gradually more precisely describing the strange nature of the autistic withdrawal and schizophrenic apragmatism. At therapeutic era, negative symptoms have taken over the positive symptoms to establish an operational criteria whose importance lies in the progressive severity of this clinical type and in their contribution to therapeutic resistance. Despite the efforts of modern typological classifications, this work rehabilitates the old concept of "unitary psychosis" by defining a common symptomatic core to multiple clinical forms of psychosis, combining deficit of emotional expression and avolition, meaning a native psychopathology and a pathophysiology possibly in a common final way, and calling the arrival of new treatment strategies. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  15. Blood Culture-Negative Endocarditis, Morocco. (United States)

    Boudebouch, Najma; Sarih, M'hammed; Chakib, Abdelfattah; Fadili, Salma; Boumzebra, Drissi; Zouizra, Zahira; Mahadji, Badie Azamane; Amarouch, Hamid; Raoult, Didier; Fournier, Pierre-Edouard


    We investigated the microorganisms causing blood culture-negative endocarditis (BCNE) in Morocco. We tested 19 patients with BCNE by serologic methods, molecular methods, or both and identified Bartonella quintana, Staphylococcus aureus, Streptococcus equi, and Streptococcus oralis in 4 patients. These results highlight the role of these zoonotic agents in BCNE in Morocco.

  16. Are there negative returns to aid?

    NARCIS (Netherlands)

    Lensink, Robert; White, Howard


    The World Bank report Assessing Aid assumes that aid is more effective when it is given to countries where polices are sound. Moreover, it assumes that an inflow of aid, above a certain level, starts to have negative effects. In this paper we empirically test both assumptions. We do not find

  17. The Positive Side of Negative Labelling

    NARCIS (Netherlands)

    Dam, van Y.K.; Jonge, de J.


    Ethical labels signal positive ethical quality of a product but fail to create massive demand for such products. Based on regulatory focus theory and prospect theory, it is argued that negative signalling of low ethical quality would have a stronger effect on the adoption of ethical products than

  18. Revisiting the gram-negative lipoprotein paradigm (United States)

    The processing of lipoproteins (lpps) in Gram-negative bacteria is generally considered to be an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein n-acyltransferase. The mature lipoproteins are then sorted...

  19. Exploring the Psychological Influence of Perceived Negative ...

    African Journals Online (AJOL)

    Nneka Umera-Okeke


    Oct 14, 2017 ... Abstract. This paper critically examined the psychological influence of perceived negative foreign factors which were those obstacles brought to Nigeria and Nigerians since our first contact with the European colonialists. The obstacles have constituted formidable barriers to indigenous organisational ...

  20. Implicit and explicit negation in logic programming

    NARCIS (Netherlands)

    Jonker, C.M.

    The focus of the research is the semantics of logic programming. Concepts in the currently used semantics like negation as failure, the Closed World Assumption and multivalued interpretations need to be thoroughly understood in order to develop semantics for extensions of the logic programming

  1. Clinicopathological comparison of triple negative breast cancers ...

    African Journals Online (AJOL)

    Key words: Basal subtype, estrogen receptor, hormone receptors, human epidermal growth factor receptor‑2/neu, progesterone receptor, triple negative. Date of Acceptance: 10‑Nov‑2014. Introduction. Breast cancer is by far the most frequent cancer among women worldwide with an estimated 1.38 million new cases of ...

  2. Attentional bias to negative affect moderates negative affect's relationship with smoking abstinence. (United States)

    Etcheverry, Paul E; Waters, Andrew J; Lam, Cho; Correa-Fernandez, Virmarie; Vidrine, Jennifer Irvin; Cinciripini, Paul M; Wetter, David W


    To examine whether initial orienting (IO) and inability to disengage (ITD) attention from negative affective stimuli moderate the association of negative affect with smoking abstinence during a quit attempt. Data were from a longitudinal cohort study of smoking cessation (N = 424). A negative affect modified Stroop task was administered 1 week before and on quit day to measure IO and ITD. Ecological Momentary Assessments were used to create negative affect intercepts and linear slopes for the week before quitting and on quit day. Quit day and long-term abstinence measures were collected. Continuation ratio logit model analyses found significant interactions for prequit negative affect slope with prequit ITD, odds ratio (OR) = 0.738 (0.57, 0.96), p = .02, and for quit day negative affect intercept with quit day ITD, OR = 0.62 (0.41, 950), p = .03, predicting abstinence. The Prequit Negative Affect Intercept × Prequit IO interaction predicting quit day abstinence was significant, OR = 1.42 (1.06, 1.90), p = .02, as was the Quit Day Negative Affect Slope × Quit Day IO interaction predicting long-term abstinence, OR = 1.45 (1.02, 2.08), p = .04. The hypothesis that the association of negative affect with smoking abstinence would be moderated by ITD was generally supported. Among individuals with high ITD, negative affect was inversely related to abstinence, but unrelated to abstinence among individuals with lower levels of ITD. Unexpectedly, among individuals with low IO, negative affect was inversely related to abstinence, but unrelated to abstinence among individuals with higher levels of ITD. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  3. Revisiting the Gram-negative lipoprotein paradigm. (United States)

    LoVullo, Eric D; Wright, Lori F; Isabella, Vincent; Huntley, Jason F; Pavelka, Martin S


    The processing of lipoproteins (Lpps) in Gram-negative bacteria is generally considered an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein N-acyltransferase. The mature lipoproteins are then sorted by the Lol system, with most Lpps inserted into the outer membrane (OM). We demonstrate here that the lnt gene is not essential to the Gram-negative pathogen Francisella tularensis subsp. tularensis strain Schu or to the live vaccine strain LVS. An LVS Δlnt mutant has a small-colony phenotype on sucrose medium and increased susceptibility to globomycin and rifampin. We provide data indicating that the OM lipoprotein Tul4A (LpnA) is diacylated but that it, and its paralog Tul4B (LpnB), still sort to the OM in the Δlnt mutant. We present a model in which the Lol sorting pathway of Francisella has a modified ABC transporter system that is capable of recognizing and sorting both triacylated and diacylated lipoproteins, and we show that this modified system is present in many other Gram-negative bacteria. We examined this model using Neisseria gonorrhoeae, which has the same Lol architecture as that of Francisella, and found that the lnt gene is not essential in this organism. This work suggests that Gram-negative bacteria fall into two groups, one in which full lipoprotein processing is essential and one in which the final acylation step is not essential, potentially due to the ability of the Lol sorting pathway in these bacteria to sort immature apolipoproteins to the OM. This paper describes the novel finding that the final stage in lipoprotein processing (normally considered an essential process) is not required by Francisella tularensis or Neisseria gonorrhoeae. The paper provides a potential reason for this and shows that it may be widespread in other Gram-negative bacteria. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  4. Negative ion beam extraction in ROBIN

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, Gourab, E-mail: [Institute for Plasma Research (IPR), Bhat, Gandhinagar, Gujarat 382428 (India); Gahlaut, Agrajit; Soni, Jignesh; Pandya, Kaushal; Parmar, Kanu G.; Pandey, Ravi; Vuppugalla, Mahesh; Prajapati, Bhavesh; Patel, Amee; Mistery, Hiren [Institute for Plasma Research (IPR), Bhat, Gandhinagar, Gujarat 382428 (India); Chakraborty, Arun; Bandyopadhyay, Mainak; Singh, Mahendrajit J.; Phukan, Arindam; Yadav, Ratnakar K.; Parmar, Deepak [ITER-India, Institute for Plasma Research, A-29, Sector 25, GIDC, Gandhinagar, Gujarat 380025 (India)


    Highlights: ► A RF based negative hydrogen ion beam test bed has been set up at IPR, India. ► Ion source has been successfully commissioned and three campaigns of plasma production have been carried out. ► Extraction system (35 kV) has been installed and commissioning has been initiated. Negative ion beam extraction is immediate milestone. -- Abstract: The RF based single driver −ve ion source experiment test bed ROBIN (Replica Of BATMAN like source in INDIA) has been set up at Institute for Plasma Research (IPR), India in a technical collaboration with IPP, Garching, Germany. A hydrogen plasma of density 5 × 10{sup 12} cm{sup −3} is expected in driver region of ROBIN by launching 100 kW RF power into the driver by 1 MHz RF generator. The cesiated source is expected to deliver a hydrogen negative ion beam of 10 A at 35 kV with a current density of 35 mA/cm{sup 2} as observed in BATMAN. In first phase operation of the ROBIN ion source, a hydrogen plasma has been successfully generated (without extraction system) by coupling 80 kW RF input power through a matching network with high power factor (cos θ > 0.8) and different plasma parameters have been measured using Langmuir probes and emission spectroscopy. The plasma density of 2.5 × 10{sup 11} cm{sup −3} has been measured in the extraction region of ROBIN. For negative hydrogen ion beam extraction in second phase operation, extraction system has been assembled and installed with ion source on the vacuum vessel. The source shall be first operated in volume mode for negative ion beam extraction. The commissioning of the source with high voltage power supply has been initiated.

  5. Characterization of Hemagglutinin Negative Botulinum Progenitor Toxins

    Directory of Open Access Journals (Sweden)

    Suzanne R. Kalb


    Full Text Available Botulism is a disease involving intoxication with botulinum neurotoxins (BoNTs, toxic proteins produced by Clostridium botulinum and other clostridia. The 150 kDa neurotoxin is produced in conjunction with other proteins to form the botulinum progenitor toxin complex (PTC, alternating in size from 300 kDa to 500 kDa. These progenitor complexes can be classified into hemagglutinin positive or hemagglutinin negative, depending on the ability of some of the neurotoxin-associated proteins (NAPs to cause hemagglutination. The hemagglutinin positive progenitor toxin complex consists of BoNT, nontoxic non-hemagglutinin (NTNH, and three hemagglutinin proteins; HA-70, HA-33, and HA-17. Hemagglutinin negative progenitor toxin complexes contain BoNT and NTNH as the minimally functional PTC (M-PTC, but not the three hemagglutinin proteins. Interestingly, the genome of hemagglutinin negative progenitor toxin complexes comprises open reading frames (orfs which encode for three proteins, but the existence of these proteins has not yet been extensively demonstrated. In this work, we demonstrate that these three proteins exist and form part of the PTC for hemagglutinin negative complexes. Several hemagglutinin negative strains producing BoNT/A, /E, and /F were found to contain the three open reading frame proteins. Additionally, several BoNT/A-containing bivalent strains were examined, and NAPs from both genes, including the open reading frame proteins, were associated with BoNT/A. The open reading frame encoded proteins are more easily removed from the botulinum complex than the hemagglutinin proteins, but are present in several BoNT/A and /F toxin preparations. These are not easily removed from the BoNT/E complex, however, and are present even in commercially-available purified BoNT/E complex.

  6. Seeing ghosts: Negative body evaluation predicts overestimation of negative social feedback

    NARCIS (Netherlands)

    Alleva, J.M.; Lange, W.G.; Jansen, A.T.M.; Martijn, C.


    The current study investigated whether negative body evaluation predicts women's overestimation of negative social feedback related to their own body (i.e., covariation bias). Sixty-five female university students completed a computer task where photos of their own body, of a control woman's body,

  7. Locating Sites of Negations and Denegating "Negative Essentializing": Rereading Virginia Woolf's "A Room of One's Own" (United States)

    Adhikari, Manahari


    This essay examines how Virginia Woolf uses writing as a tool to locate sites of negations, such as women's exclusion from places of power and knowledge, and to expose negative essentializing that permeates patriarchal structure in "A Room of One's Own." Whereas scholarship on the book has explored a wide range of issues including sex,…

  8. Sentential Negative Markers as Pro-Forms of Negative Sentences in Modern Mongolian (United States)

    Dagvasumberel, Enkhjargal


    Negation in modern Mongolian was analyzed by scholars namely: Luvsanvandan Sh (1968, 2000), Wonsoo Yu (1991), Mönkh-Amgalan Yu (1998), Purev-Ochir B. (1998, 2001), Byambasan P. (2006), Kunihiko Hasimoto (2008), BatIreedui J.(2009), Ravdan E. (2009), Mönkh-Amgalan Yu & Kan Shin (2014). Sentential negation in modern Mongolian is not sufficiently…

  9. Negative cognitive errors and positive illusions for negative divorce events: predictors of children's psychological adjustment. (United States)

    Mazur, E; Wolchik, S A; Sandler, I N


    This study examined the relations among negative cognitive errors regarding hypothetical negative divorce events, positive illusions about those same events, actual divorce events, and psychological adjustment in 38 8- to 12-year-old children whose parents had divorced within the previous 2 years. Children's scores on a scale of negative cognitive errors (catastrophizing, overgeneralizing, and personalizing) correlated significantly with self-reported symptoms of anxiety and self-esteem, and with maternal reports of behavior problems. Children's scores on a scale measuring positive illusions (high self-regard, illusion of personal control, and optimism for the future) correlated significantly with less self-reported aggression. Both appraisal types accounted for variance in some measures of symptomatology beyond that explained by actual events. There was no significant association between children's negative cognitive errors and positive illusions. The implications of these results for theories of negative cognitive errors and of positive illusions, as well as for future research, are discussed.

  10. Negative ion beam programs at JAERI (United States)

    Ohara, Y.


    Three negative ion beam programs for nuclear fusion research are proposed at the Japan Atomic Energy Research Institute (JAERI): a 500 keV, 10 MW deuterium neutral beam injection (NBI) for heating and current drive in the JT-60U tokamak, a 0.5/1 MeV, 50 MW deuterium beam injection for the Fusion Experimental Reactor (FER), and a 2 MeV, 20 mA lithium beam injection for ion temperature measurement in the JT-60U. The 500 keV negative-ion-based NBI system for the JT-60U will be developed in the first step, followed by the development of the reactor relevant 0.5/1 MeV NBI system. This two step development mitigates the risk in developing a MeV class NBI system.

  11. Negative electrodes for lithium cells and batteries

    Energy Technology Data Exchange (ETDEWEB)

    Vaughey, John T.; Fransson, Linda M.; Thackeray, Michael M.


    A negative electrode is disclosed for a non-aqueous electrochemical cell. The electrode has an intermetallic compound as its basic structural unit with the formula M.sub.2 M' in which M and M' are selected from two or more metal elements including Si, and the M.sub.2 M' structure is a Cu.sub.2 Sb-type structure. Preferably M is Cu, Mn and/or Li, and M' is Sb. Also disclosed is a non-aqueous electrochemical cell having a negative electrode of the type described, an electrolyte and a positive electrode. A plurality of cells may be arranged to form a battery.

  12. Multipole-bound molecular negative ions

    CERN Document Server

    Abdul-Karim, H; Desfrançois, C


    Within the framework of a simple electrostatic model, as compared to recent experimental results, we here discuss the stability of very weakly bound molecular negative ions. In contrast with the case of conventional valence anions, the excess electron is then located in a very diffuse orbital and is mainly bound by electrostatic dipolar, quadrupolar, and polarization forces, at large distances from the neutral molecular core. By fitting a single repulsion parameter of the model to the available experimental data, it is possible to make quantitative predictions of the excess-electron binding energies in these species. Critical values of the dipole moment, quadrupole moment or polarizability required for the observation of stable multipole-bound negative ions are predicted and compared to available experimental data and ab initio calculations. Refs. 26 (author)

  13. Magnetic levitation from negative permeability materials

    Energy Technology Data Exchange (ETDEWEB)

    Coffey, Mark W., E-mail: [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States)


    As left-handed materials and metamaterials are becoming more prevalent, we examine the effect of negative permeability upon levitation force. We first consider two half spaces of differing permeability and a point magnetic source, so that the method of images may be employed. We determine that the resulting force may be larger than for conventional magnetic materials. We then illustrate the inclusion of a finite sample thickness. -- Highlights: ► The effect of negative permeability upon levitation force is considered. ► Such an effect could be realized with metamaterials. ► The resulting force may be larger than with conventional materials. ► The analysis is extended to allow for a finite sample thickness. ► Representative numerical values are given.

  14. Strategy to Avoid Negative Perception on Game

    Directory of Open Access Journals (Sweden)

    Yedija Prima Putra


    Full Text Available In the beginning, games are made to provide entertainment. But, with the interesting entertainment, some game developers use that just for their own benefit. Moreover, many of them including elements of violence and pornography on their games. That is just only to make more profit for them. Thats why some parents are anxious and have a bad view of games. But, not all of the games have elements of violence and pornography. Some of developers make game which is including educational value. "Crazy Machines 2" is one of many games which has educational value. This is one of the ways to Avoid Negative Perception on Game. Key Word : game, creativity, strategy, avoid negative perception

  15. Negative emotional stimuli enhance vestibular processing. (United States)

    Preuss, Nora; Ellis, Andrew W; Mast, Fred W


    Recent studies have shown that vestibular stimulation can influence affective processes. In the present study, we examined whether emotional information can also modulate vestibular perception. Participants performed a vestibular discrimination task on a motion platform while viewing emotional pictures. Six different picture categories were taken from the International Affective Picture System: mutilation, threat, snakes, neutral objects, sports, and erotic pictures. Using a Bayesian hierarchical approach, we were able to show that vestibular discrimination improved when participants viewed emotionally negative pictures (mutilation, threat, snake) when compared to neutral/positive objects. We conclude that some of the mechanisms involved in the processing of vestibular information are also sensitive to emotional content. Emotional information signals importance and mobilizes the body for action. In case of danger, a successful motor response requires precise vestibular processing. Therefore, negative emotional information improves processing of vestibular information. (c) 2015 APA, all rights reserved).

  16. Negative permittivity in bubble and stripe phases (United States)

    Friess, B.; Peng, Y.; Rosenow, B.; von Oppen, F.; Umansky, V.; von Klitzing, K.; Smet, J. H.


    The physics of itinerant electrons in condensed matter is by and large governed by repulsive Coulomb forces. However, attractive interactions may emerge and prevail in determining the ground state despite the pervasive Coulomb repulsion. A notable example is electron pairing and superconductivity. The interplay of attractive and repulsive interactions may also instigate spontaneous symmetry lowering and clustering of charges in geometric patterns even without net attraction. Both types of attractive interaction triggered physics--pairing and charge ordering--are at play in two-dimensional electron systems exposed to a quantizing magnetic field. The charge ordering has been concluded indirectly from transport behaviour. Here we report the observation of negative permittivity present solely when bubble and stripe phases form. In conjunction with a theoretical model, the negative permittivity provides evidence for the underlying attractive exchange-correlation energy which sufficiently countervails Coulomb repulsion at small distances to enable and mediate charge clustering.

  17. Nociception, pain, negative moods and behavior selection (United States)

    Baliki, Marwan N.; Apkarian, A. Vania


    Recent neuroimaging studies suggest that the brain adapts with pain, as well as imparts risk for developing chronic pain. Within this context we revisit the concepts for nociception, acute and chronic pain, and negative moods relative to behavior selection. We redefine nociception as the mechanism protecting the organism from injury; while acute pain as failure of avoidant behavior; and a mesolimbic threshold process that gates the transformation of nociceptive activity to conscious pain. Adaptations in this threshold process are envisioned to be critical for development of chronic pain. We deconstruct chronic pain into four distinct phases, each with specific mechanisms; and outline current state of knowledge regarding these mechanisms: The limbic brain imparting risk, while mesolimbic learning processes reorganizing the neocortex into a chronic pain state. Moreover, pain and negative moods are envisioned as a continuum of aversive behavioral learning, which enhance survival by protecting against threats. PMID:26247858

  18. Structures with negative index of refraction (United States)

    Soukoulis, Costas M [Ames, IA; Zhou, Jiangfeng [Ames, IA; Koschny, Thomas [Ames, IA; Zhang, Lei [Ames, IA; Tuttle, Gary [Ames, IA


    The invention provides simplified negative index materials (NIMs) using wire-pair structures, 4-gap single ring split-ring resonator (SRR), fishnet structures and overleaf capacitor SRR. In the wire-pair arrangement, a pair of short parallel wires and continuous wires are used. In the 4-gap single-ring SRR, the SRRs are centered on the faces of a cubic unit cell combined with a continuous wire type resonator. Combining both elements creates a frequency band where the metamaterial is transparent with simultaneously negative .di-elect cons. and .mu.. In the fishnet structure, a metallic mesh on both sides of the dielectric spacer is used. The overleaf capacitor SRR changes the gap capacities to small plate capacitors by making the sections of the SRR ring overlap at the gaps separated by a thin dielectric film. This technique is applicable to conventional SRR gaps but it best deploys for the 4-gap single-ring structures.

  19. Ghost plasmon and negative dielectric function (United States)

    Takayanagi, Kazuo; Lipparini, Enrico


    We show explicitly that a negative value of the static dielectric function necessarily means the existence of what might be called a ``ghost plasmon,'' a pole of the screened response χsc(q,ω) on the imaginary axis of ω. The ghost plasmon is a collective state exhausting most of the conductivity sum rule. This is demonstrated for a two-dimensional electron gas with a microscopic calculation.

  20. Features of triple-negative breast cancer


    Plasilova, Magdalena L.; Hayse, Brandon; Killelea, Brigid K.; Horowitz, Nina R; Chagpar, Anees B.; Donald R. Lannin


    Abstract The aim of this study was to determine the features of triple-negative breast cancer (TNBC) using a large national database. TNBC is known to be an aggressive subtype, but national epidemiologic data are sparse. All patients with invasive breast cancer and known molecular subtype diagnosed in 2010 to 2011 were identified from the National Cancer Data Base (NCDB). Patients with and without TNBC were compared with respect to their sociodemographic and clinicopathologic features. TNBC w...

  1. Adjuvant Therapy of Triple Negative Breast Cancer


    Perez, Edith A.; Moreno-Aspitia, Alvaro; Thompson, E. Aubrey; Andorfer, Cathy A


    Patients with the triple negative subtype of breast cancer have an overall poor outcome, with earlier relapses, distinct patterns of metastases, and lack of specific targets for treatment selection. Classification of these tumors has begun to be modified by inclusion of immunohistochemistry for various markers, and gene profiling, to further characterize this subtype of breast cancer, may aid in the identification of new targeted therapies. Anthracyclines and taxanes remain the standard of ca...

  2. Multiband Negative Permittivity Metamaterials and Absorbers

    Directory of Open Access Journals (Sweden)

    Yiran Tian


    Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

  3. Enforced Sparse Non-Negative Matrix Factorization (United States)


    mixture of topics constitutes a document. Other common methods for topic modeling include the following: latent semantic analysis (LSA) [1...probabilistic latent semantic analysis (PLSA) [2], and term frequency- inverse document frequency (TF-IDF) [3] analysis. More recently, non-negative matrix...3, pp. 993–1022, 2003. [2] T. Hofmann, “Probabilistic latent semantic indexing,” in Proceedings of the 22nd Annual International ACM SIGIR

  4. Uniform Refraction in Negative Refractive Index Materials

    CERN Document Server

    Gutierrez, Cristian E


    We study the problem of constructing an optical surface separating two homogeneous, isotropic media, one of which has a negative refractive index. In doing so, we develop a vector form of Snell's law, which is used to study surfaces possessing a certain uniform refraction property, both in the near and far field cases. In the near field problem, unlike the case when both materials have positive refractive index, we show that the resulting surfaces can be neither convex nor concave.

  5. Anisotropic and Negative Acoustic Index Metamaterials


    Fok, Lee Ren


    Microstructured materials are used in material science and engineering to attain desired material properties. Acoustic metamaterials are a rapidly growing area in this field of engineered materials that use deep subwavelength microstructures to attain exotic acoustic properties unavailable in nature. These properties, such as negative acoustic index, allow unprecedented capabilities such as sub-diffraction limit resolution, which have the potential to greatly improve existing technologies l...

  6. Veillonella, Firmicutes: Microbes disguised as Gram negatives. (United States)

    Vesth, Tammi; Ozen, Aslı; Andersen, Sandra C; Kaas, Rolf Sommer; Lukjancenko, Oksana; Bohlin, Jon; Nookaew, Intawat; Wassenaar, Trudy M; Ussery, David W


    The Firmicutes represent a major component of the intestinal microflora. The intestinal Firmicutes are a large, diverse group of organisms, many of which are poorly characterized due to their anaerobic growth requirements. Although most Firmicutes are Gram positive, members of the class Negativicutes, including the genus Veillonella, stain Gram negative. Veillonella are among the most abundant organisms of the oral and intestinal microflora of animals and humans, in spite of being strict anaerobes. In this work, the genomes of 24 Negativicutes, including eight Veillonella spp., are compared to 20 other Firmicutes genomes; a further 101 prokaryotic genomes were included, covering 26 phyla. Thus a total of 145 prokaryotic genomes were analyzed by various methods to investigate the apparent conflict of the Veillonella Gram stain and their taxonomic position within the Firmicutes. Comparison of the genome sequences confirms that the Negativicutes are distantly related to Clostridium spp., based on 16S rRNA, complete genomic DNA sequences, and a consensus tree based on conserved proteins. The genus Veillonella is relatively homogeneous: inter-genus pair-wise comparison identifies at least 1,350 shared proteins, although less than half of these are found in any given Clostridium genome. Only 27 proteins are found conserved in all analyzed prokaryote genomes. Veillonella has distinct metabolic properties, and significant similarities to genomes of Proteobacteria are not detected, with the exception of a shared LPS biosynthesis pathway. The clade within the class Negativicutes to which the genus Veillonella belongs exhibits unique properties, most of which are in common with Gram-positives and some with Gram negatives. They are only distantly related to Clostridia, but are even less closely related to Gram-negative species. Though the Negativicutes stain Gram-negative and possess two membranes, the genome and proteome analysis presented here confirm their place within the

  7. ANCA-negative Churg-Strauss Syndrome

    Directory of Open Access Journals (Sweden)

    Syed Jamil Abdal


    Full Text Available A rare and a disease of unknown etiology, Churg-Strauss syndrome (CSS is a granulomatous necrotizing small vessel vasculitis characterized by the presence of asthma, sinusitis, and hypereosinophilia, which is initially described by Churg and Strauss in 1951. Because of its clinical and pathological features that overlap with those of the other anti-neutrophil antibody (ANCA-associated systemic vasculitides (AASVs and now the disease is classified as AASVs. The ANCA status may dictate the clinical phenotype. ANCA-positive patients are significantly more likely to have disease manifesta­tions associated with small-vessel vasculitis, including oecrotising glomemlonephritis, mononeuritis and purpura, whereas ANCA-negative cases predominantly likely to have cardiac and lung involvement. The objective of this case report is to point out the possibility of vasculitic rash in ANCA-negative CSS in a 35-year-old man and the disease rarely occurs in Bangladeshi population. We analyze the history, clinical examinations and relevant investigations related to the patient to establish the diagnosis in our department. The clinical scenario and biopsy help us to attain the diagnosis. But due to unavailability of patients' cohort we have limitations of comparison of ANCA status in Bangladeshi populations. Though ANCA-positive and ANCA-negative CSS differ phenotypically, primary therapy for both the conditions is systemic glucocorticoids. Additional immunosuppressive agents like cyclophosphamide, mycophenolate mofetil, azathioprine, rituxin1ab are occasionally added in patients with more advanced or refractory disease.


    Directory of Open Access Journals (Sweden)

    sema eryücel


    Full Text Available ABSTRACT Recently, insufficiency of secular coping methods has drawn the attention of researchers towards religious coping methods. While the parts about theory and model cover an important place in the literature, experimental studies are rapidly going on. Although religious coping was initially interpreted as positive, experimental studies reveal that it also has negative forms. The purpose of this study, in which qualitative research methods were used, is to define the components of religious coping. Semi structured interview was used among 42 participants, 9 war veterans from Association of Turkish Disabled War Veterans, Martyrs, their Widows and Orphans Ankara Branch, and 9 relatives of martyrs from the Association of Martyrs’ Families Ankara Branch, totaling 60 volunteer participants between the ages 25 and 65 with snowball sampling method. It was discovered that 29 of the participants used negative religious coping and the participants who only used negative religious coping were studied in this research. Upon recording the interviews with the aid of a recorder, the researched typed the script of the interviews. The qualitative analysis of the collected data was done in MAXODA 11 computer program.

  9. Negative Results in European Psychology Journals

    Directory of Open Access Journals (Sweden)

    Martin Rachev Vasilev


    Full Text Available Psychologists have long speculated that the research literature is largely dominated by positive findings, but yet there is little data to justify these speculations. The present study investigates the extent to which negative findings exist in the literature by reviewing articles published in five European psychology journals. While no temporal change was observed, the results indicate that almost all (95.4% articles published in 2001, 2006 and 2011 found support for at least one tested hypothesis. Moreover, a sizable number (73% of papers found support for all tested hypotheses. It is argued that the lack of negative findings can have a detrimental effect on the ability to systemize scientific knowledge, the way science is practiced, and the rate of replications in psychology. Publishing positive findings may be very important for making progress in our field, but negative findings are also crucial for maintaining its scientific integrity. When we base our conclusions on results that support our predictions and ignore data to the contrary, we run the risk of creating a biased view of reality that gives us little confidence in the validity and applicability of our findings.

  10. Negative Knudsen force on heated microbeams

    KAUST Repository

    Zhu, Taishan


    Knudsen force acting on a heated microbeam adjacent to a cold substrate in a rarefied gas is a mechanical force created by unbalanced thermal gradients. The measured force has its direction pointing towards the side with a lower thermal gradient and its magnitude vanishes in both continuum and free-molecule limits. In our previous study, negative Knudsen forces were discovered at the high Knudsen regime before diminishing in the free-molecule limit. Such a phenomenon was, however, neither observed in experiment [A. Passian et al., Phys. Rev. Lett. 90, 124503 (2003)], nor captured in the latest numerical study [J. Nabeth et al., Phys. Rev. E 83, 066306 (2011)]. In this paper, the existence of such a negative Knudsen force is further confirmed using both numerical simulation and theoretical analysis. The asymptotic order of the Knudsen force near the collisionless limit is analyzed and the analytical expression of its leading term is provided, from which approaches for the enhancement of negative Knudsen forces are proposed. The discovered phenomenon could find its applications in novel mechanisms for pressure sensing and actuation.

  11. Negative Halogen Ions for Fusion Applications

    Energy Technology Data Exchange (ETDEWEB)

    Grisham, L.R.; Kwan, J.W.; Hahto, S.K.; Hahto, S.T.; Leung, K.N.; Westenskow, G.


    Over the past quarter century, advances in hydrogen negative ion sources have extended the usable range of hydrogen isotope neutral beams to energies suitable for large magnetically confined fusion devices. Recently, drawing upon this experience, negative halogen ions have been proposed as an alternative to positive ions for heavy ion fusion drivers in inertial confinement fusion, because electron accumulation would be prevented in negative ion beams, and if desired, the beams could be photo-detached to neutrals. This paper reports the results of an experiment comparing the current density and beam emittance of Cl+ and Cl- extracted from substantially ion-ion plasmas with that of Ar+ extracted from an ordinary electron-ion plasma, all using the same source, extractor, and emittance scanner. At similar discharge conditions, the Cl- current was typically 85 – 90% of the positive chlorine current, with an e-/ Cl- ratio as low as seven without grid magnets. The Cl- was as much as 76% of the Ar+ current from a discharge with the same RF drive. The minimum normalized beam emittance and inferred ion temperatures of Cl+, Cl-, and Ar+ were all similar, so the current density and optical quality of Cl- appear as suitable for heavy ion fusion driver applications as a positive noble gas ion of similar mass. Since F, I, and Br should all behave similarly in an ion source, they should also be suitable as driver beams.

  12. Direct Laser Writing of Magneto-Photonic Sub-Microstructures for Prospective Applications in Biomedical Engineering. (United States)

    Au, Thi Huong; Trinh, Duc Thien; Tong, Quang Cong; Do, Danh Bich; Nguyen, Dang Phu; Phan, Manh-Huong; Lai, Ngoc Diep


    We report on the fabrication of desired magneto-photonic devices by a low one-photon absorption (LOPA) direct laser writing (DLW) technique on a photocurable nanocomposite consisting of magnetite ( Fe 3 O 4 ) nanoparticles and a commercial SU-8 photoresist. The magnetic nanocomposite was synthesized by mixing Fe 3 O 4 nanoparticles with different kinds of SU-8 photoresists. We demonstrated that the degree of dispersion of Fe 3 O 4 nanoparticles in the nanocomposite depended on the concentration of Fe 3 O 4 nanoparticles, the viscosity of SU-8 resist, and the mixing time. By tuning these parameters, the most homogeneous magnetic nanocomposite was obtained with a concentration of about 2 wt % of Fe 3 O 4 nanoparticles in SU-8 2005 photoresist for the mixing time of 20 days. The LOPA-based DLW technique was employed to fabricate on demand various magneto-photonic submicrometer structures, which are similar to those obtained without Fe 3 O 4 nanoparticles. The magneto-photonic 2D and 3D structures with sizes as small as 150 nm were created. We demonstrated the strong magnetic field responses of the magneto-photonic nanostructures and their use as micro-actuators when immersed in a liquid solution.

  13. Direct Laser Writing of Magneto-Photonic Sub-Microstructures for Prospective Applications in Biomedical Engineering

    Directory of Open Access Journals (Sweden)

    Thi Huong Au


    Full Text Available We report on the fabrication of desired magneto-photonic devices by a low one-photon absorption (LOPA direct laser writing (DLW technique on a photocurable nanocomposite consisting of magnetite ( Fe 3 O 4 nanoparticles and a commercial SU-8 photoresist. The magnetic nanocomposite was synthesized by mixing Fe 3 O 4 nanoparticles with different kinds of SU-8 photoresists. We demonstrated that the degree of dispersion of Fe 3 O 4 nanoparticles in the nanocomposite depended on the concentration of Fe 3 O 4 nanoparticles, the viscosity of SU-8 resist, and the mixing time. By tuning these parameters, the most homogeneous magnetic nanocomposite was obtained with a concentration of about 2 wt % of Fe 3 O 4 nanoparticles in SU-8 2005 photoresist for the mixing time of 20 days. The LOPA-based DLW technique was employed to fabricate on demand various magneto-photonic submicrometer structures, which are similar to those obtained without Fe 3 O 4 nanoparticles. The magneto-photonic 2D and 3D structures with sizes as small as 150 nm were created. We demonstrated the strong magnetic field responses of the magneto-photonic nanostructures and their use as micro-actuators when immersed in a liquid solution.

  14. Negative Mood Increases Selective Attention to Negatively Valenced Body Parts in Female Adolescents with Anorexia Nervosa. (United States)

    Svaldi, Jennifer; Bender, Caroline; Caffier, Detlef; Ivanova, Viliana; Mies, Nina; Fleischhaker, Christian; Tuschen-Caffier, Brunna


    Previous research has yielded evidence of increased attentional processing of negatively valenced body parts in women with anorexia nervosa (AN), especially for those with high depressive symptomatology. The present study extended previous research by implementing an experimental mood manipulation. In a within-subjects design, female adolescents with AN (n = 12) and an age matched female control group (CG; n = 12) were given a negative and a positive mood induction at a one-week interval. After each mood induction, participants underwent a 3-min mirror exposure, while their eye movements were recorded. After the positive mood induction, both AN and CG participants displayed longer and more frequent gazes towards their self-defined most ugly relative to their self-defined most beautiful body part. However, after the negative mood induction, only females with AN were characterized by increased attention to their most ugly compared to their most beautiful body part, while CG participants' attention distribution was balanced. Furthermore, in the negative (but not in the positive) mood induction condition gaze frequency and duration towards the most ugly body part was significantly stronger in the AN group relative to the CG. The results emphasize the role of negative mood in the maintenance of pathological information processing of the self-body. This increased body-related negativity-bias during negative mood may lead to the persistence and aggravation of AN patients' body image disturbance.

  15. Gram-negative bacteraemia in haemodialysis. (United States)

    Murray, Eleanor C; Marek, Aleksandra; Thomson, Peter C; Coia, John E


    Patients on renal replacement therapy experience higher rates of morbidity and mortality, infection being the second commonest cause of death. In our haemodialysis population, we identify the pathogens, sensitivity patterns, sources of infection and outcomes of Gram-negative bacteraemia. Data from the NHS Greater Glasgow & Clyde and NHS Forth Valley haemodialysis population were collected July 2011 to April 2014 through an interrogation of the renal unit electronic patient record, and confirmed by an independent search of the Microbiology database. Over 544 377 haemodialysis days, 84 patients experienced 95 Gram-negative bacteraemia events, a rate of 0.175 events per 1000 haemodialysis days, which varied with dialysis modality: non-tunnelled central venous catheters 4.77, arteriovenous grafts 0.24, tunnelled central venous catheters 0.21, and arteriovenous fistulae 0.11 per 1000 haemodialysis days. The commonest sources of bacteraemia were central venous catheters (CVCs) (16.8%, n = 16), infected ulcers (14.7%, n = 14), urinary (10.5%, n = 10), biliary (9.5%, n = 9) and intra-abdominal (9.5%, n = 9).The principal organisms were Escherichia coli (49.5%, n = 47), Enterobacter spp. (13.1%, n = 13), Klebsiella spp. (11.1%, n = 11), Proteus mirabilis (6.1%, n = 6) and Pseudomonas aeruginosa (5.1%, n = 5). Of the Enterobacteriaceae (n = 84), 88% were sensitive to gentamicin, 81% to ciprofloxacin, 91% to piperacillin-tazobactam and 100% were sensitive to meropenem.Three-month case mortality was 25.3% (n = 24). Ten patients (11.9%) had more than one Gram-negative bacteraemia; of these, nine patients (90.0%) were the same causative organism, predominantly E. coli. CVCs and diabetic foot ulcers remain significant risk factors for Gram-negative bacteraemia, highlighting the importance of vascular access planning. Despite good levels of antibiotic sensitivity, the early mortality following Gram-negative bacteraemia remains high, supporting aggressive treatment of such

  16. Dependency Parser-based Negation Detection in Clinical Narratives. (United States)

    Sohn, Sunghwan; Wu, Stephen; Chute, Christopher G


    Negation of clinical named entities is common in clinical documents and is a crucial factor to accurately compile patients' clinical conditions and to further support complex phenotype detection. In 2009, Mayo Clinic released the clinical Text Analysis and Knowledge Extraction System (cTAKES), which includes a negation annotator that identifies negation status of a named entity by searching for negation words within a fixed word distance. However, this negation strategy is not sophisticated enough to correctly identify complicated patterns of negation. This paper aims to investigate whether the dependency structure from the cTAKES dependency parser can improve the negation detection performance. Manually compiled negation rules, derived from dependency paths were tested. Dependency negation rules do not limit the negation scope to word distance; instead, they are based on syntactic context. We found that using a dependency-based negation proved a superior alternative to the current cTAKES negation annotator.

  17. The clinicopathologic characteristics and prognostic significance of triple-negativity in node-negative breast cancer (United States)

    Rhee, Jiyoung; Han, Sae-Won; Oh, Do-Youn; Kim, Jee Hyun; Im, Seock-Ah; Han, Wonshik; Ae Park, In; Noh, Dong-Young; Bang, Yung-Jue; Kim, Tae-You


    Background Triple-negative (TN) breast cancer, which is defined as being negative for the estrogen receptor (ER), the progesterone receptor (PR), and the human epidermal growth factor receptor 2 (HER-2), represents a subset of breast cancer with different biologic behaviour. We investigated the clinicopathologic characteristics and prognostic indicators of lymph node-negative TN breast cancer. Methods Medical records were reviewed from patients with node-negative breast cancer who underwent curative surgery at Seoul National University Hospital between Jan. 2000 and Jun. 2003. Clinicopathologic variables and clinical outcomes were evaluated. Results Among 683 patients included, 136 had TN breast cancer and 529 had non-TN breast cancer. TN breast cancer correlated with younger age (< 35 y, p = 0.003), and higher histologic and nuclear grade (p < 0.001). It also correlated with a molecular profile associated with biological aggressiveness: negative for bcl-2 expression (p < 0.001), positive for the epidermal growth factor receptor (p = 0.003), and a high level of p53 (p < 0.001) and Ki67 expression (p < 0.00). The relapse rates during the follow-up period (median, 56.8 months) were 14.7% for TN breast cancer and 6.6% for non-TN breast cancer (p = 0.004). Relapse free survival (RFS) was significantly shorter among patients with TN breast cancer compared with those with non-TN breast cancer (4-year RFS rate 85.5% vs. 94.2%, respectively; p = 0.001). On multivariate analysis, young age, close resection margin, and triple-negativity were independent predictors of shorter RFS. Conclusion TN breast cancer had higher relapse rate and more aggressive clinicopathologic characteristics than non-TN in node-negative breast cancer. Thus, TN breast cancer should be integrated into the risk factor analysis for node-negative breast cancer. PMID:18947390

  18. Hospital nurses? attitudes, negative perceptions, and negative acts regarding workplace bullying


    Ma, Shu-Ching; Wang, Hsiu-Hung; Chien, Tsair-Wei


    Background Workplace bullying is a prevalent problem in today?s work places that has adverse effects on both bullying victims and organizations. To investigate the predictors of workplace bullying is an important task to prevent bullying victims of nurses in hospitals. Objective This study aims to explore the relationships among nurses? attitudes, negative perceptions, and negative acts regarding workplace bullying under the framework of the theory of planned behavior (TPB). Methods A total o...

  19. Negative density-distribution relationship in butterflies

    Directory of Open Access Journals (Sweden)

    Kotiaho Janne S


    Full Text Available Abstract Background Because "laws of nature" do not exist in ecology, much of the foundations of community ecology rely on broad statistical generalisations. One of the strongest generalisations is the positive relationship between density and distribution within a given taxonomic assemblage; that is, locally abundant species are more widespread than locally sparse species. Several mechanisms have been proposed to create this positive relationship, and the testing of these mechanisms is attracting increasing attention. Results We report a strong, but counterintuitive, negative relationship between density and distribution in the butterfly fauna of Finland. With an exceptionally comprehensive data set (data includes all 95 resident species in Finland and over 1.5 million individuals, we have been able to submit several of the mechanisms to powerful direct empirical testing. Without exception, we failed to find evidence for the proposed mechanisms creating a positive density-distribution relationship. On the contrary, we found that many of the mechanisms are equally able to generate a negative relationship. Conclusion We suggest that one important determinant of density-distribution relationships is the geographical location of the study: on the edge of a distribution range, suitable habitat patches are likely to be more isolated than in the core of the range. In such a situation, only the largest and best quality patches are likely to be occupied, and these by definition can support a relatively dense population leading to a negative density-distribution relationship. Finally, we conclude that generalizations about the positive density-distribution relationship should be made more cautiously.

  20. BNL negative ion based neutral beam development

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, J.G.; Hershcovitch, A.; Kovarik, V.; Larson, R.A.; McKenzie-Wilson, R.; Prelec, K.; Sluyters, T.


    The BNL Neutral Beam Development Group has as its objective the development of neutral beam systems, using negative ion sources with high current density. In this past year we have made the transition from pulsed high current negative ion sources to sources designed to operate steady state. We are presently testing two dc sources, a magnetron source and a modified magnetron with plasma injection from a hollow cathode discharge (HCD). Both sources have operated with steady state discharges; to date 0.11A of H/sup -/ has been extracted from the standard magnetron while about 1A of H/sup -/ has been produced on a surface, but not extracted, in the HCD system. Present plans are to transport the beam from a 2A magnetron around a bending magnet, followed by dc acceleration of the beam to 200 keV. These units would be stacked to obtain higher currents. The HCD source is expected to operate at much lower pressures (10/sup -4/ - 10/sup -3/ Torr), and therefore close coupled acceleration of the beam to 200 keV is envisioned. This makes the source module considerably more compact. The MEQA-LAC, dc acceleration with periodic electrostatic quadrupole focusing, and the RFQ are being considered as ways to accelerate negative ion beams to energies above 200 keV. In the neutral beam line a novel plasma neutralizer is being considered which uses HCD's to feed a plasma into a solenoidal magnetic field. This should result in a high plasma density (10/sup 13/ - 10/sup 14/ cm/sup -3/) with a low background gas pressure.

  1. Negative pressure therapy: theory and practice. (United States)

    Schintler, M V


    Negative pressure (wound) therapy, synonymous with topical negative pressure or vacuum therapy mainly cited as branded VAC® (vacuum-assisted closure) therapy, is a mode of therapy used to encourage wound healing. It is used both as primary treatment of chronic and complex wounds and as an adjunct for temporary closure and wound bed preparation preceding surgical procedures such as skin grafts and flap surgery. The device has come into wide and successful use, although the physiological basis of its effect is not yet fully understood, and with a delay, increasingly evidence-based data become available. A meta-analysis was made of peer-reviewed publications (PubMed-Medline) chosen on the basis of inclusion of the terms randomized clinical trial, vacuum-assisted closure, and topical negative pressure. Scientific data were evaluated from experimental animal studies, randomized clinical trials, observations of clinical applications, and case reports on all known effects of VAC therapy. Systematic analysis of the data shows efficacy concerning induction of wound healing mechanisms, especially in the early stage. Increased perfusion can be considered proven. Data analysis shows positive efficacy for treatment of infection. Although this therapy appears effective and its superiority to conventional techniques has been demonstrated, there are still some critical votes concerning efficacy. Because its mechanisms of action remain unclear, and because there is still some gap between evidence-based data and the excellent clinical results, further prospective, randomized, blinded studies are needed. Even so, we conclude that vacuum therapy, used when indicated and especially by experienced surgeons, is an excellent tool to support wound healing. Copyright © 2012 John Wiley & Sons, Ltd.

  2. Ghost plasmon and negative dielectric function

    Energy Technology Data Exchange (ETDEWEB)

    Takayanagi, K. [Department of Physics, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102 (Japan); Lipparini, E. [Dipartimento di Fisica, Universita degli Studi di Trento and Gruppo Collegato, Istituto Nazionale di Fisica Nucleare, Trento, I-38050 Povo Trento (Italy)


    We show explicitly that a negative value of the static dielectric function necessarily means the existence of what might be called a {open_quotes}ghost plasmon,{close_quotes} a pole of the screened response {chi}{sup sc}(q,{omega}) on the imaginary axis of {omega}. The ghost plasmon is a collective state exhausting most of the conductivity sum rule. This is demonstrated for a two-dimensional electron gas with a microscopic calculation. {copyright} {ital 1997} {ital The American Physical Society}

  3. Quorum sensing in gram-negative bacteria

    DEFF Research Database (Denmark)

    Wu, H.; Song, Z.J.; Høiby, N.


    Bacteria can communicate with each other by means of signal molecules to coordinate the behavior of the entire community, and the mechanism is referred to as quorum sensing (QS). Signal systems enable bacteria to sense the size of their densities by monitoring the concentration of the signal...... molecules. Among Gram-negative bacteria N-acyl-L-homoserine lactone (acyl-HSL)-dependent quorum sensing systems are particularly widespread. These systems are used to coordinate expression of phenotypes that are fundamental to the interaction of bacteria with each other and with their environment...

  4. Genetic Susceptibility to Triple Negative Breast Cancer


    Stevens, Kristen N.; Vachon, Celine M.; Couch, Fergus J.


    Triple negative breast cancers (TNBC), defined by the absence of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 expression, account for 12-24% of all breast cancers. TNBC is associated with early recurrence of disease and poor outcome. Germline mutations in the BRCA1 and BRCA2 breast cancer susceptibility genes have been associated with up to 15% of TNBC, and TNBC accounts for 70% of breast tumors arising in BRCA1 mutation carriers and 16-23% of breast ...

  5. Single-resonator double-negative metamaterial (United States)

    Warne, Larry K.; Basilio, Lorena I.; Langston, William L.; Johnson, William A.; Ihlefeld, Jon; Ginn, III, James C.; Clem, Paul G.; Sinclair, Michael B.


    Resonances can be tuned in dielectric resonators in order to construct single-resonator, negative-index metamaterials. For example, high-contrast inclusions in the form of metallic dipoles can be used to shift the first electric resonance down (in frequency) to the first magnetic resonance, or alternatively, air splits can be used to shift the first magnetic resonance up (in frequency) near the first electric resonance. Degenerate dielectric designs become especially useful in infrared- or visible-frequency applications where the resonator sizes associated with the lack of high-permittivity materials can become of sufficient size to enable propagation of higher-order lattice modes in the resulting medium.

  6. Trees and Fields and Negative Polarity

    DEFF Research Database (Denmark)

    Vikner, Sten


    The paper takes as its point of departure a comparison between two kinds of approaches to clause structure, namely tree analyses like the generative analysis and field analyses like the sætningsskema analysis of Danish of Diderichsen (1946) and many others (or like the topologische Modell analysi...... to accounting for negative polarity items in English, Danish and German, both the more straightforward aspects and the more complex ones, e.g. the so-called NPI-verbs as well as the interaction between NPI-elements and because-clauses...

  7. Culture Negative Infective Endocarditits: a Changing Paradigm

    LENUS (Irish Health Repository)

    Daly, A


    Traditionally, the modified Duke\\'s criteria, based primarily on positive blood cultures, is used to diagnose Infective Endocarditis (IE). However, reports demonstrate that 31% of cases are diagnosed as Culture Negative Infective Endocarditis (CNIE)1. Consequently, empiric broad-spectrum antibiotics are prescribed to cover unidentified organisms and, as a result, antibiotic therapy may be compromised. Molecular diagnostic techniques aid with identifying causative organisms in cases of CNIE and we question if the increasing use of such technologies will change the local epidemiology of CNIE. We present the first case of Tropheryma whipplei Infective Endocarditis (TWIE) reported in Ireland.




    The finding that attraction is a function of attitude similarity has been interpreted as a special case of the effect of positive and negative reinforcements on attraction. A simple discrimination learning task was employed in which the reinforcements were attitude statements similar and dissimilar to the opinions of the subject. The presentation of similar attitude statements after each correct response and dissimilar attitude statements after each incorrect response significantly changed response probability. The hypothesis that such statements could be used as reinforcers in a learning situation was thus confirmed.

  9. Statistical simulation of photoresists at EUV and ArF (United States)

    Biafore, John J.; Smith, Mark D.; Mack, Chris A.; Thackeray, James W.; Gronheid, Roel; Robertson, Stewart A.; Graves, Trey; Blankenship, David


    Requirements of resist modeling strategies for EUV and low-k1 ArF nanolithography continue to become more stringent. Resist designers are consistently faced with the task of reducing exposure dose and line roughness while simultaneously improving exposure latitude, depth-of-focus and ultimate resolution. In this work, we briefly discuss a next-generation resist model for the prediction of statistical resist responses such as line-edge roughness, line-width roughness and CD variability, as well as base lithographic responses such as exposure latitude. The model's parameterized fit to experimental data from a state-of-the art polymer-bound PAG resist irradiated at ArF and EUV will be shown. The probabilistic computation of acid generation at ArF and EUV will be discussed. The factors influencing the hypothesized primary cause of resist roughness, acid shot noise, are discussed.

  10. Stochastic exposure kinetics of EUV photoresists: a simulation study (United States)

    Mack, Chris A.; Thackeray, James W.; Biafore, John J.; Smith, Mark D.


    BACKGROUND: The stochastic nature of extreme ultraviolet (EUV) resist exposure leads to variations in the resulting acid concentration, which leads to line-edge roughness (LER) of the resulting features. METHODS: Using a stochastic resist simulator, we predicted the mean and standard deviation of the acid concentration for an open-frame exposure and fit the results to analytical expressions. RESULTS: The EUV resist exposure mechanism of the PROLTIH Stochastic Resist Simulator is first order, and an analytical expression for the exposure rate constant C allows prediction of the mean acid concentration of an open-frame exposure to about 1% accuracy over a wide range of parameter values. A second analytical expression for the standard deviation of the acid concentration also matched the output of PROLITH to within about 1%. CONCLUSIONS: Predicting the stochastic uncertainty in acid concentration for EUV resists allows optimization of resist processing and formulations, and may form the basis of a comprehensive LER model.


    Energy Technology Data Exchange (ETDEWEB)

    Schantz, L. E.


    Untrimmed hybrid microcircuit networks require dimensional dontrol to maintain critical electrical parameters within the required tolert.- ances. Dimensional integrity can be maintained by parameter manipulation and control. Five processing parameters affect the dimensional stability of the pattern: the prebake time-temperature product, exposure energy, developing time and concentration, resist thickness uniformity, and etchant undercutting. By adjusting the relative dominance of those parameters and by. optimizing the value of each, the total dimensional deviation can be made relatively insensitive to normal process variations. Thus, process characterization and control methods which will maintain one-percent dimensional control on lines as narrow as 5.0 mils - (127 Km) can be established.

  12. Designing of high-resolution photoresists: use of modern NMR ...

    Indian Academy of Sciences (India)


    eds) J. R Sheats and B W Smith (USA: Marcel Dekker) p. 429. Voigt Anja 1999 Ph.D. Thesis, Humboldt University, Berlin. Wallraff G M and Hinsberg W D 1999 Chem. Rev. 99 1801. Zöllinger H 1994 Diazo chemistry I: Aromatic and heterocyclic.

  13. Designing of high-resolution photoresists: use of modern NMR ...

    Indian Academy of Sciences (India)

    Applications of improved 1-D/ 2-D NMR spectroscopic techniques have been reviewed for quantitatively estimating the incorporation of different monomers and degree of linearity in resin microstructure. Comparison of the NMR data with those from lithography leads to a distinct correlation between resin microstructure and ...

  14. NANOFILM - New metallic nanocomposites for micro and nanofabrication

    DEFF Research Database (Denmark)

    Fischer, Søren Vang

    or catalysts. The possibility to effectively structure the nanocomposites are however a limiting factor. In this project the UV sensitive photoresist SU-8 gold and silver nanocomposites have been fabricated which can be deposited and structured using standard micro and nanofabrication processes....... A technique called pre grafting was found to be most effective for the stabilisation process. In pre grafting the nanoparticles were formed in the presence of PVP-VA. For the two metal nanocomposites attempted to be fabricated only the gold SU-8 nanocomposite was successfully and reproducibly produced...... was then chosen for as co-solvent which resulted in a successfully structured in situ silver SU-8 nanocomposite. For both the ex situ and in situ nanocomposites structuring was initially found to be troublesome. Complete cross-linking of the SU-8 was only found to be possible after removing the filter from...

  15. Doubled strings, negative strings and null waves

    Energy Technology Data Exchange (ETDEWEB)

    Blair, Chris D.A. [Theoretische Natuurkunde, Vrije Universiteit Brussel, and the International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)


    We revisit the fundamental string (F1) solution in the doubled formalism. We show that the wave-like solution of double field theory (DFT) corresponding to the F1/pp-wave duality pair is more properly a solution of the DFT action coupled to a doubled sigma model action. The doubled string configuration which sources the pp-wave can be thought of as static gauge with the string oriented in a dual direction. We also discuss the DFT solution corresponding to a vibrating string, carrying both winding and momentum. We further show that the solution dual to the F1 in both time and space can be viewed as a “negative string” solution. Negative branes are closely connected to certain exotic string theories which involve unusual signatures for both spacetime and brane worldvolumes. In order to better understand this from the doubled point of view, we construct a variant of DFT suitable for describing theories in which the fundamental string has a Euclidean worldsheet, for which T-dualities appear to change the spacetime signature.

  16. Development of versatile multiaperture negative ion sources (United States)

    Cavenago, M.; Serianni, G.; Antoni, V.; Bigi, M.; De Muri, M.; Pasqualotto, R.; Recchia, M.; Veltri, P.; Agostinetti, P.; Barbisan, M.; Baseggio, L.; Cervaro, V.; Cazzador, M.; Degli Agostini, F.; Franchin, L.; Kulevoy, T.; Laterza, B.; Mimo, A.; Minarello, A.; Petrenko, S.; Ravarotto, D.; Rossetto, F.; Sattin, M.; Zaniol, B.; Zucchetti, S.


    Enhancement of negative ion sources for production of large ion beams is a very active research field nowadays, driven from demand of plasma heating in nuclear fusion devices and accelerator applications. As a versatile test bench, the ion source NIO1 (Negative Ion Optimization 1) is being commissioned by Consorzio RFX and INFN. The nominal beam current of 135 mA at -60 kV is divided into 9 beamlets, with multiaperture extraction electrodes. The plasma is sustained by a 2 MHz radiofrequency power supply, with a standard matching box. A High Voltage Deck (HVD) placed inside the lead shielding surrounding NIO1 contains the radiofrequency generator, the gas control, electronics and power supplies for the ion source. An autonomous closed circuit water cooling system was installed for the whole system, with a branch towards the HVD, using carefully optimized helical tubing. Insulation transformer is installed in a nearby box. Tests of several magnetic configurations can be performed. Status of experiments, measured spectra and plasma luminosity are described. Upgrades of magnetic filter, beam calorimeter and extraction grid and related theoretical issues are reviewed.

  17. Inflation and Growth: Positive or Negative Relationship? (United States)

    Berument, Hakan; Inamlik, Ali; Olgun, Hasan

    This study has been motivated by two developments. Firstly, by the vast literature on the relationship between inflation and growth which is abundantly endowed with diverse theoretical explanations and contradictory evidence and by the unique experience of the Turkish economy with inflation and growth. A preliminary examination of the Turkish data pointed to a negative relation between inflation and growth. Moreover, there is a unanimous agreement among the students of the Turkish economy that many factors have contributed to inflation in this country. In view of these facts this paper employs a VAR model which will enable us to identify the sources of the shocks and control for external factors. In addition VAR models have a high predictive power and enable the researcher to observe the impulse response functions. The study employs Generalised Impulse Response analysis. In the empirical experiments oil prices, money supply, government spending and taxes have been taken as the most likely determinants of inflation. The study shows that there is a negative relationship between inflation and output growth in Turkey and that the underlying explanatory factor is the real exchange rate. This result is robust.

  18. Nitric oxide negatively regulates mammalian adult neurogenesis (United States)

    Packer, Michael A.; Stasiv, Yuri; Benraiss, Abdellatif; Chmielnicki, Eva; Grinberg, Alexander; Westphal, Heiner; Goldman, Steven A.; Enikolopov, Grigori


    Neural progenitor cells are widespread throughout the adult central nervous system but only give rise to neurons in specific loci. Negative regulators of neurogenesis have therefore been postulated, but none have yet been identified as subserving a significant role in the adult brain. Here we report that nitric oxide (NO) acts as an important negative regulator of cell proliferation in the adult mammalian brain. We used two independent approaches to examine the function of NO in adult neurogenesis. In a pharmacological approach, we suppressed NO production in the rat brain by intraventricular infusion of an NO synthase inhibitor. In a genetic approach, we generated a null mutant neuronal NO synthase knockout mouse line by targeting the exon encoding active center of the enzyme. In both models, the number of new cells generated in neurogenic areas of the adult brain, the olfactory subependyma and the dentate gyrus, was strongly augmented, which indicates that division of neural stem cells in the adult brain is controlled by NO and suggests a strategy for enhancing neurogenesis in the adult central nervous system.

  19. Distance Sensitive Bloom Filters Without False Negatives

    DEFF Research Database (Denmark)

    Goswami, Mayank; Pagh, Rasmus; Silvestri, Francesco


    A Bloom filter is a widely used data-structure for representing a set S and answering queries of the form “Is x in S?”. By allowing some false positive answers (saying ‘yes’ when the answer is in fact ‘no’) Bloom filters use space significantly below what is required for storing S. In the distance...... sensitive setting we work with a set S of (Hamming) vectors and seek a data structure that offers a similar trade-off, but answers queries of the form “Is x close to an element of S?” (in Hamming distance). Previous work on distance sensitive Bloom filters have accepted false positive and false negative...... answers. Absence of false negatives is of critical importance in many applications of Bloom filters, so it is natural to ask if this can be also achieved in the distance sensitive setting. Our main contributions are upper and lower bounds (that are tight in several cases) for space usage in the distance...

  20. Human choice under schedules of negative reinforcement. (United States)

    Alessandri, Jérôme; Cançado, Carlos R X


    The generalized matching equation provides a good description of response allocation in concurrent schedules of positive reinforcement in nonhumans as well as in humans. The present experiment was conducted to further investigate the allocation of responding under concurrent schedules of negative reinforcement (i.e., timeouts from pressing a force cell) in humans. Each of three participants was exposed to different reinforcement ratios (9:1, 1:1 and 1:9) in the terminal links of a concurrent-chains schedule of negative reinforcement. The allocation of responding under this schedule was well described by the generalized matching equation, for each participant. These results replicate previous findings obtained with nonhumans and humans under concurrent schedules of positive reinforcement. In addition, they extend the results reported by Alessandri and Rivière (2013) showing that human behavior maintained by timeouts from an effortful response is sensitive to changes in relative reinforcement ratios as well as relative delays of reinforcement. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Will Automated Vehicles Negatively Impact Traffic Flow?

    Directory of Open Access Journals (Sweden)

    S. C. Calvert


    Full Text Available With low-level vehicle automation already available, there is a necessity to estimate its effects on traffic flow, especially if these could be negative. A long gradual transition will occur from manual driving to automated driving, in which many yet unknown traffic flow dynamics will be present. These effects have the potential to increasingly aid or cripple current road networks. In this contribution, we investigate these effects using an empirically calibrated and validated simulation experiment, backed up with findings from literature. We found that low-level automated vehicles in mixed traffic will initially have a small negative effect on traffic flow and road capacities. The experiment further showed that any improvement in traffic flow will only be seen at penetration rates above 70%. Also, the capacity drop appeared to be slightly higher with the presence of low-level automated vehicles. The experiment further investigated the effect of bottleneck severity and truck shares on traffic flow. Improvements to current traffic models are recommended and should include a greater detail and understanding of driver-vehicle interaction, both in conventional and in mixed traffic flow. Further research into behavioural shifts in driving is also recommended due to limited data and knowledge of these dynamics.

  2. Negative probability of random multiplier in turbulence (United States)

    Bai, Xuan; Su, Weidong


    The random multiplicative process (RMP), which has been proposed for over 50 years, is a convenient phenomenological ansatz of turbulence cascade. In the RMP, the fluctuation in a large scale is statistically mapped to the one in a small scale by the linear action of an independent random multiplier (RM). Simple as it is, the RMP is powerful enough since all of the known scaling laws can be included in this model. So far as we know, however, a direct extraction for the probability density function (PDF) of RM has been absent yet. The reason is the deconvolution during the process is ill-posed. Nevertheless, with the progress in the studies of inverse problems, the situation can be changed. By using some new regularization techniques, for the first time we recover the PDFs of the RMs in some turbulent flows. All the consistent results from various methods point to an amazing observation-the PDFs can attain negative values in some intervals; and this can also be justified by some properties of infinitely divisible distributions. Despite the conceptual unconventionality, the present study illustrates the implications of negative probability in turbulence in several aspects, with emphasis on its role in describing the interaction between fluctuations at different scales. This work is supported by the NSFC (No. 11221062 and No. 11521091).

  3. Universal corner contributions to entanglement negativity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Keun-Young, E-mail: [School of Physics and Chemistry, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Niu, Chao, E-mail: [School of Physics and Chemistry, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Pang, Da-Wei, E-mail: [Mathematical Sciences and STAG Research Centre, University of Southampton, Southampton SO17 1BJ (United Kingdom)


    It has been realised that corners in entangling surfaces can induce new universal contributions to the entanglement entropy and Rényi entropy. In this paper we study universal corner contributions to entanglement negativity in three- and four-dimensional CFTs using both field theory and holographic techniques. We focus on the quantity χ defined by the ratio of the universal part of the entanglement negativity over that of the entanglement entropy, which may characterise the amount of distillable entanglement. We find that for most of the examples χ takes bigger values for singular entangling regions, which may suggest increase in distillable entanglement. However, there also exist counterexamples where distillable entanglement decreases for singular surfaces. We also explore the behaviour of χ as the coupling varies and observe that for singular entangling surfaces, the amount of distillable entanglement is mostly largest for free theories, while counterexample exists for free Dirac fermion in three dimensions. For holographic CFTs described by higher derivative gravity, χ may increase or decrease, depending on the sign of the relevant parameters. Our results may reveal a more profound connection between geometry and distillable entanglement.

  4. LINGO-1 negatively regulates myelination by oligodendrocytes. (United States)

    Mi, Sha; Miller, Robert H; Lee, Xinhua; Scott, Martin L; Shulag-Morskaya, Svetlane; Shao, Zhaohui; Chang, Jufang; Thill, Greg; Levesque, Melissa; Zhang, Mingdi; Hession, Cathy; Sah, Dinah; Trapp, Bruce; He, Zhigang; Jung, Vincent; McCoy, John M; Pepinsky, R Blake


    The control of myelination by oligodendrocytes in the CNS is poorly understood. Here we show that LINGO-1 is an important negative regulator of this critical process. LINGO-1 is expressed in oligodendrocytes. Attenuation of its function by dominant-negative LINGO-1, LINGO-1 RNA-mediated interference (RNAi) or soluble human LINGO-1 (LINGO-1-Fc) leads to differentiation and increased myelination competence. Attenuation of LINGO-1 results in downregulation of RhoA activity, which has been implicated in oligodendrocyte differentiation. Conversely, overexpression of LINGO-1 leads to activation of RhoA and inhibition of oligodendrocyte differentiation and myelination. Treatment of oligodendrocyte and neuron cocultures with LINGO-1-Fc resulted in highly developed myelinated axons that have internodes and well-defined nodes of Ranvier. The contribution of LINGO-1 to myelination was verified in vivo through the analysis of LINGO-1 knockout mice. The ability to recapitulate CNS myelination in vitro using LINGO-1 antagonists and the in vivo effects seen in the LINGO-1 knockout indicate that LINGO-1 signaling may be critical for CNS myelination.

  5. EDITORIAL: Negative ion based neutral beam injection (United States)

    Hemsworth, R. S.


    It is widely recognized that neutral beam injection (NBI), i.e. the injection of high energy, high power, beams of H or D atoms, is a flexible and reliable system that has been the main heating system on a large variety of fusion devices, and NBI has been chosen as one of the three heating schemes of the International Tokomak Reactor (ITER). To date, all the NBI systems but two have been based on the neutralization (in a simple gas target) of positive hydrogen or deuterium ions accelerated to 1 MeV/nucleon. Unfortunately H- and D- are difficult to create, and the very characteristic that makes them attractive, the ease with which the electron is detached from the ion, means that it is difficult to create high concentrations or fluxes of them, and it is difficult to avoid substantial, collisional, losses in the extraction and acceleration processes. However, there has been impressive progress in negative ion sources and accelerators over the past decade, as demonstrated by the two pioneering, operational, multi-megawatt, negative ion based, NBI systems at LHD (180 keV, H0) and JT-60U (500 keV, D0), both in Japan. Nevertheless, the system proposed for ITER represents a substantial technological challenge as an increase is required in beam energy, to 1 MeV, D0, accelerated ion (D-) current, to 40 A, accelerated current density, 200 A m-2 of D-, and pulse length, to 1 h. At the Fourth IAEA Technical Meeting on Negative Ion Based Neutral Beam Injectors, hosted by the Consorzio RFX, Padova, Italy, 9-11 May 2005, the status of the R&D aimed at the realization of the injectors for ITER was presented. Because of the importance of this development to the success of the ITER project, participants at that meeting were asked if they were interested in rewriting and extending their contributions as a submission to Nuclear Fusion. Technology papers were accepted because of the very nature of the subject. The submissions underwent the regular double-referee peer-review process

  6. BRCA1/2-negative hereditary triple-negative breast cancers exhibit BRCAness. (United States)

    Domagala, Pawel; Hybiak, Jolanta; Cybulski, Cezary; Lubinski, Jan


    BRCA1/2-associated breast cancers are sensitive to poly(ADPribose) polymerase (PARP) inhibitors and platinum compounds mainly due to their deficiency in DNA repair via homologous recombination (HR). However, approximately only 15% of triple-negative breast cancers (TNBCs) are BRCA1/2-associated. TNBCs that exhibit BRCAness (a phenotype reflecting impaired HR in BRCA1/2-negative tumors) are also regarded sensitive to PARP inhibitors and platinum compounds. Thus, we hypothesized that hereditary BRCA1/2-negative TNBCs may exhibit BRCAness. To find a subset of hereditary BRCA1/2-negative TNBCs among 360 TNBCs, we first identified a group of 41 hereditary TNBCs by analyzing the family histories of the patients. Next, we tested this group for the presence of germline BRCA1/2 mutations, and finally, we compared the expression levels of 120 genes involved in HR and five other major mechanisms of DNA damage repair between BRCA1/2-associated and BRCA1/2-negative subgroups of hereditary TNBCs using real-time PCR arrays. Approximately 73% of the hereditary TNBCs were BRCA1/2-associated and 27% were BRCA1/2-negative. The expression levels of the analyzed genes showed no significant differences between these two subgroups indicating the BRCAness of the BRCA1/2-negative hereditary TNBCs and thereby distinguishing a novel subset of TNBCs as a potential target for PARP inhibitors or platinum-based therapy. The results show the significance of family history in selecting patients with TNBC for therapies directed at incompetent DNA repair (e.g., PARP inhibitors and/or platinum-based therapies) and indicate that a relatively simple strategy for broadening the target group for these modes of treatment is to identify patients with hereditary TNBCs. © 2016 UICC.

  7. Evaluation of negative energy Coulomb (Whittaker) functions (United States)

    Noble, C. J.


    This paper describes a code for evaluating exponentially decaying negative energy Coulomb functions and their first derivatives with respect to the radial variable. The functions, which correspond to Whittaker functions of the second kind, are obtained to high accuracy for a wide range of parameters using recurrence techniques. Program summaryTitle of program: whittaker_w Catalog identifier: ADSZ Program summary URL: Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: Cray T3E, Sun Ultra-5_10 sparc, Origin2000, Compaq EV67, IBM SP3, Toshiba 460CDT Operating systems under which the program has been tested: Windows NT4, Redhat Linux, SunOS 5.8 Programming language used: Fortran 95 Memory required to run with typical data: 500 KB Number of bytes in distributed program, including test data, etc.: 39728 Number of lines in distributed program, including test data, etc.: 2900 Distribution format: tar gzip file Nature of physical problem: The closed-channel components of the asymptotic radial wave function corresponding to electron or positron scattering by atomic or molecular ions may be expressed in terms of negative energy Coulomb functions. The scattering observables are obtained from S or T matrices which in turn are obtained by matching the radial and asymptotic wavefunctions at a finite radial point. Recent large scale scattering calculations have required accurate values of the Coulomb functions at smaller ρ values and larger negative η values than previous work. The present program is designed to extend the range of parameters for which the function may be calculated. Method of solution: Recurrence relations, power series expansion, numerical quadrature. Restrictions on the complexity of the problem: The program has been tested for the parameter ranges: 0< ρ⩽1000, | η|⩽120 and 0⩽ l⩽100. These ranges may, with appropriate scaling to avoid underflow and overflow, be

  8. Freeze or Flee? Negative Stimuli Elicit Selective Responding (United States)

    Estes, Zachary; Verges, Michelle


    Humans preferentially attend to negative stimuli. A consequence of this automatic vigilance for negative valence is that negative words elicit slower responses than neutral or positive words on a host of cognitive tasks. Some researchers have speculated that negative stimuli elicit a general suppression of motor activity, akin to the freezing…

  9. Negative probability in the framework of combined probability


    Burgin, Mark


    Negative probability has found diverse applications in theoretical physics. Thus, construction of sound and rigorous mathematical foundations for negative probability is important for physics. There are different axiomatizations of conventional probability. So, it is natural that negative probability also has different axiomatic frameworks. In the previous publications (Burgin, 2009; 2010), negative probability was mathematically formalized and rigorously interpreted in the context of extende...

  10. Negative Concord in Afrikaans: Filling the typological gap

    NARCIS (Netherlands)

    Biberauer, T.; Zeijlstra, H.


    Many languages exhibit Negative Concord (NC), with multiple morphosyntactic instances of negation corresponding to one semantic negation. Traditionally, NC languages are distinguished as Strict and Non-strict (cf. Giannakidou 2000). In the former (e.g. Czech), multiple negative elements may or even

  11. Brand Suicide? Memory and Liking of Negative Brand Names.

    Directory of Open Access Journals (Sweden)

    Duncan Guest

    Full Text Available Negative brand names are surprisingly common in the marketplace (e.g., Poison perfume; Hell pizza, and Monster energy drink, yet their effects on consumer behavior are currently unknown. Three studies investigated the effects of negative brand name valence on brand name memory and liking of a branded product. Study 1 demonstrates that relative to non-negative brand names, negative brand names and their associated logos are better recognised. Studies 2 and 3 demonstrate that negative valence of a brand name tends to have a detrimental influence on product evaluation with evaluations worsening as negative valence increases. However, evaluation is also dependent on brand name arousal, with high arousal brand names resulting in more positive evaluations, such that moderately negative brand names are equally as attractive as some non-negative brand names. Study 3 shows evidence for affective habituation, whereby the effects of negative valence reduce with repeated exposures to some classes of negative brand name.

  12. A neurocomputational model of the mismatch negativity.

    Directory of Open Access Journals (Sweden)

    Falk Lieder

    Full Text Available The mismatch negativity (MMN is an event related potential evoked by violations of regularity. Here, we present a model of the underlying neuronal dynamics based upon the idea that auditory cortex continuously updates a generative model to predict its sensory inputs. The MMN is then modelled as the superposition of the electric fields evoked by neuronal activity reporting prediction errors. The process by which auditory cortex generates predictions and resolves prediction errors was simulated using generalised (Bayesian filtering--a biologically plausible scheme for probabilistic inference on the hidden states of hierarchical dynamical models. The resulting scheme generates realistic MMN waveforms, explains the qualitative effects of deviant probability and magnitude on the MMN - in terms of latency and amplitude--and makes quantitative predictions about the interactions between deviant probability and magnitude. This work advances a formal understanding of the MMN and--more generally--illustrates the potential for developing computationally informed dynamic causal models of empirical electromagnetic responses.

  13. Negative regulation of DNA methylation in plants. (United States)

    Saze, Hidetoshi; Sasaki, Taku; Kakutani, Tetsuji


    Cytosine methylation of repeats and genes is important for coordination of genome stability and proper gene function. In plants, DNA methylation is regulated by DNA methyltransferases, chromatin remodeling factors and RNAi machinery. Ectopic DNA hypermethylation at genes causes transcriptional repression and silencing, and the methylation patterns often become heritable over generations. DNA methylation is antagonized by the DNA demethylation enzymes. Recently, we identified a novel jmjC-domain containing gene IBM1 (increase in bonsai methylation1) that also negatively regulates DNA methylation in Arabidopsis. The ibm1 plants show a variety of developmental phenotypes. IBM1 prevents ectopic accumulation of DNA methylation at the BNS genic region, likely through removal of heterochromatic H3K9 methylation mark. DNA and histone demethylation pathways are important for genome-wide patterning of DNA methylation and for epigenetic regulation of plant development.

  14. Mismatch negativity (MMN: Translating the potential.

    Directory of Open Access Journals (Sweden)

    Juanita eTodd


    Full Text Available The mismatch negativity (MMN component of the auditory event-related potential has become a valuable tool in cognitive neuroscience. Its reduced size in persons with schizophrenia is of unknown origin but theories proposed include links to problems in experience-dependent plasticity reliant on N-methyl-d-aspartate glutamate receptors. In this review we address the utility of this tool in revealing the nature and time course of problems in perceptual inference in this illness together with its potential for use in translational research testing animal models of schizophrenia-related phenotypes. Specifically, we review the reasons for interest in MMN in schizophrenia, issues pertaining to the measurement of MMN, its use as a vulnerability index for the development of schizophrenia, the pharmacological sensitivity of MMN and the progress in developing animal models of MMN. Within this process we highlight the challenges posed by knowledge gaps pertaining to the tool and the pharmacology of the underlying system.

  15. Brief assessment of negative dysmorphic signs

    Directory of Open Access Journals (Sweden)

    Patrizia Fiori


    Full Text Available Patrizia Fiori1, Antonio Monaco1, Maria Giannetti Luigi21Central Operative Unit of Neurology, 2Infantile Neuropsychiatry and Social Service, ASL AV, Civil Hospital of Ariano Irpino, University of Naples, ItalyAbstract: Body dysmorphic disorder is a body image dysperception, characterized either by an excessive preoccupation with a presumed or minimal flaw in appearance, or by unrecognition, denial, or even neglect regarding an obvious defect. These features are evaluated by a novel questionnaire, the Brief Assessment of Negative Dysmorphic Signs (BANDS. Moreover, the temperament and character background is examined. The relationship with addictive mentality/behavior and schizoaffectivity is also highlighted. Lastly, the potential shift toward cognitive impairment and dementia is considered.Keywords: body dysmorphic disorder, schizoaffectivity, addiction, behavioral-cognitive impairment

  16. Negative autobiographical memories in social anxiety disorder

    DEFF Research Database (Denmark)

    OToole, Mia Skytte; Watson, Lynn Ann; Rosenberg, Nicole


    BACKGROUND AND OBJECTIVES: Empirical interest in mental imagery in social anxiety disorder (SAD) has grown over the past years but still little is known about the specificity to SAD. The present study therefore examines negative autobiographical memories in participants with social anxiety disorder...... (SAD), compared to patients with panic disorder (PD), and healthy controls (HCs). METHODS: A total of 107 participants retrieved four memories cued by verbal phrases associated with either social anxiety (SA) or panic anxiety (PA), with two memories for each cue category. RESULTS: PA-cued memories were...... experienced with stronger imagery and as more traumatic. They were also rated as more central to identity than SA-cued memories, but not among participants with SAD, who perceived SA-cued memories as equally central to their identity. When between-group effects were detected, participants with anxiety...

  17. Formation of Voids from Negative Density Perturbations (United States)

    de Araujo, J. C. N.; Opher, R.


    RESUMEN. Se estudia la formaci6n de huecos a partir de un espectro negativo de perturbaciones, tomando en cuenta la expansi6n del Universo, arrastre por fotones, enfriamiento por fotones, fotoionizaci6n, ioniza- ci6n colisional, enfriamiento Lyman a y la formaci6n y enfriamiento de moleculas H2. Nuestros resultados predicen la existencia de regiones 1/10 de Ia densidad promedio para regiones de masa lO - 1O10M . ABSTRACT. In the present paer we study the formation of voids from a negative spectrum of perturbations taking into account the expansion of the Universe, photon-drag, photon-cooling, photoionization, collisional ionization, Lyman a cooling and the formation and cooling of 112 molecules. Our results predict the existence of regions 1/10 the average density for regions of mass 1O - 1O10M@ : CLUSTERS-GALAXIES - COSMOLOGY

  18. Nosewitness identification: effects of negative emotion.

    Directory of Open Access Journals (Sweden)

    Laura Alho

    Full Text Available Every individual has a unique body odor (BO, similar to a fingerprint. In forensic research, identification of culprit BOs has been performed by trained dogs, but not by humans. We introduce the concept of nosewitness identification and present the first experimental results on BO memory in witness situations involving violent crimes. Two experiments indicated that BO associated with male characters in authentic videos could later be identified in BO lineup tests well above chance. Moreover, culprit BO in emotional crime videos could be identified considerably better than the BO of a male person in neutral videos. This indicates that nosewitness identification benefits from emotional encoding. Altogether, the study testifies to the virtue of body odor as a cue to identify individuals observed under negative emotion.

  19. Triple negative breast cancer: an Indian perspective

    Directory of Open Access Journals (Sweden)

    Akhtar M


    Full Text Available Murtaza Akhtar, Subhrajit Dasgupta, Murtuza Rangwala Department of Surgery, NKP Salve Institute of Medical Sciences and Research Centre, Nagpur, Maharashtra, India Introduction: Breast cancer is the most common female cancer in the world. Triple negative breast cancer (TNBC is a recently identified biological variant with aggressive tumor behavior and poor prognosis. Data of hormonal status from the Indian population is scarce due to financial constraints in performing immunohistochemistry evaluation. The present study aims to prospectively analyze receptor status of all breast cancer patients and identify TNBC and compare their clinical profile and short term survival with other non-TNBC group. Materials and methods: All cytologically and histopathologically confirmed cases of carcinoma breast were prospectively enrolled. In a longitudinal study at tertiary care hospital in central India based on the hormonal status, they were further divided into TNBC and other groups. Comparison of risk factors, clinical profile and short-term survival was carried out. Results: A total 85 patients were enrolled and of them 37 (43.7% were TNBC. On comparing risk factors ie, age, age at menarche, total reproductive age, age at first child birth, and menopausal status – no statistical significance was observed between the TNBC and non-TNBC groups. But on comparison of clinical profile TNBC tumors were significantly large with majority of patients presenting as locally advanced breast cancer (83%. No statistical difference was observed in axillary lymph node status between two groups. TNBC tumors were histologically more aggressive (grade 3 compared to other groups. No statistically significant difference was observed in short term overall survival but all three deaths were observed in the TNBC group only and two local recurrences after surgery were observed in the TNBC group. Conclusion: TNBC forms a large proportion of carcinoma breast patients in a central

  20. [Negative symptoms, emotion and cognition in schizophrenia]. (United States)

    Fakra, E; Belzeaux, R; Azorin, J-M; Adida, M


    For a long time, treatment of schizophrenia has been essentially focussed on positive symptoms managing. Yet, even if these symptoms are the most noticeable, negative symptoms are more enduring, resistant to pharmacological treatment and associated with a worse prognosis. In the two last decades, attention has shift towards cognitive deficit, as this deficit is most robustly associated to functional outcome. But it appears that the modest improvement in cognition, obtained in schizophrenia through pharmacological treatment or, more purposely, by cognitive enhancement therapy, has only lead to limited amelioration of functional outcome. Authors have claimed that pure cognitive processes, such as those evaluated and trained in lots of these programs, may be too distant from real-life conditions, as the latter are largely based on social interactions. Consequently, the field of social cognition, at the interface of cognition and emotion, has emerged. In a first part of this article we examined the links, in schizophrenia, between negative symptoms, cognition and emotions from a therapeutic standpoint. Nonetheless, investigation of emotion in schizophrenia may also hold relevant premises for understanding the physiopathology of this disorder. In a second part, we propose to illustrate this research by relying on the heuristic value of an elementary marker of social cognition, facial affect recognition. Facial affect recognition has been repeatedly reported to be impaired in schizophrenia and some authors have argued that this deficit could constitute an endophenotype of the illness. We here examined how facial affect processing has been used to explore broader emotion dysfunction in schizophrenia, through behavioural and imaging studies. In particular, fMRI paradigms using facial affect have shown particular patterns of amygdala engagement in schizophrenia, suggesting an intact potential to elicit the limbic system which may however not be advantageous. Finally, we


    Directory of Open Access Journals (Sweden)

    Marína Maglovski


    Full Text Available Arsenic (As belongs to heavy metals and its accumulation in plants, besides damaging the organism itself, represents a potential health risk to animal and human consumers. Therefore, contamination of soils and waters with this compound is a serious environmental problem. In this work we focused on investigating a negative impact of As on selected parameters of growth of wheat plants (Triticum aestivum L. cv. Genoveva grown in hydropony. In the stage of first assimilation leaves we applied a solution of heavy metal (1 As3+ on wheat plants. For plants grown under hydropony conditions we observed different plant parameters such as length, weight, amount of fresh and dry biomass. Further we analyzed accumulation of hydrogen peroxide and products membrane lipid peroxidation as indicators of oxidative stress. In addition to these we also measured the content of photosynthetic pigments, maximal quantum yield and proline in plant tissue. Our data indicate reduction of the biomass of shoots forthcoming as a result of exposure of stressed plants to As. Decline of biomass accumulation was accompanied by increase of hydrogen peroxide in plant tissue. In contrast, level of lipid peroxidation was suppressed in stressed shoots. Contents of photosynthetic pigments soundly decreased. Interestingly, fluorescence (Fp=Fm in stressed wheat shoots increased. Similarly in tested shoots the content of proline was increased. The results indicate that the applied dose of As has a negative impact on the growth and photosynthetic performance of stressed plants. A better understanding of the mechanisms responsible for As resistance and toxicity in plants requires further investigation.

  2. Circulating steroids negatively correlate with tinnitus. (United States)

    Chrbolka, Pavel; Palúch, Zoltán; Hill, Martin; Alušík, Štefan


    While not a disease entity in itself; symptoms of tinnitus (from Latin tinnio - clink) accompany a number of diseases. Tinnitus prevalence increases with age, deteriorates one's quality of life, and may even result in suicidal behavior. Tinnitus develops in response to a variety of risk factors, otoxic substances, noise exposure, hearing disorders, and psychological alterations. Tinnitus is closely related to mood, depression, and psychological state. In the present study, we focused on alterations of the steroid metabolome and particularly neuroactive, neuroprotective, and immunomodulatory steroids in patients with tinnitus. The study group consisted of 28 patients without evidence of an organic cause of tinnitus as well as without associated diseases or the effect of ototoxic medications. All patients underwent a complete audiological assessment and laboratory tests including routine biochemical markers and quantification of circulating steroids using gas chromatography/mass spectrometry and immunoassays. To rule out a pathology in the cerebellopontine angle area, CT scan or MRI were performed. To diagnose stem lesions, evoked potentials were also measured. Pearson's correlations and multivariate regression were used to assess any links between tinnitus intensity and frequency on the one hand, and steroid levels on the other. Results indicated a significant and consistent negative correlation between tinnitus indices and intensity of adrenal steroidogenesis. The circulating steroid metabolome including hormones and neuroactive, neuroprotective, and immunomodulatory steroids negatively correlates with the degree of tinnitus due to hypothalamo-pituitary-adrenal axis malfunction. Our results may help explain the pathophysiology of tinnitus and improve its diagnosis. However, further studies are needed to verify our postulation. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. The negative ion source test facility ELISE

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, B., E-mail: [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85748 Garching (Germany); Falter, H.-D.; Fantz, U.; Franzen, P.; Froeschle, M.; Kraus, W.; Martens, C.; Nocentini, R.; Riedl, R.; Speth, E.; Staebler, A. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Postfach 1533, D-85748 Garching (Germany)


    The ITER neutral beam system is using inductively coupled radio frequency (RF) ion sources, that have demonstrated the required ITER parameters on (small) sources with extraction areas up to 200 cm{sup 2}. As a next step towards the full size ITER source IPP is presently constructing the test facility ELISE ('Extraction from a Large Ion Source Experiment') operating with a 'half-size' source which has approximately the width but only half the height of the ITER source. The modular driver concept is expected to allow a further extrapolation to the full size in one direction to be made. The main aim of this experiment is to demonstrate the production of a large uniform negative ion beam with ITER relevant parameters in stable conditions up to one hour. Plasma operation of the source is foreseen to be performed continuously for 1 h; extraction and acceleration of negative ions up to 60 kV is only possible in pulsed mode (10 s every 180 s) due to limitations of the existing IPP HV system. The design of the source and extraction system implements a high experimental flexibility and a good diagnostic access while still staying as close as possible to the ITER design. The main differences are the source operating in air and the use of a large gate valve between the source and the target chamber. ELISE is expected to start operation at the end of 2011 and is an important step for the development of the ITER NBI system; the experience gained early will support the design as well as the commissioning and operating phases of the PRIMA NBI test facilities and the ITER neutral beam system.

  4. Update on Aire and thymic negative selection. (United States)

    Passos, Geraldo A; Speck-Hernandez, Cesar A; Assis, Amanda F; Mendes-da-Cruz, Daniella A


    Twenty years ago, the autoimmune regulator (Aire) gene was associated with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy, and was cloned and sequenced. Its importance goes beyond its abstract link with human autoimmune disease. Aire identification opened new perspectives to better understand the molecular basis of central tolerance and self-non-self distinction, the main properties of the immune system. Since 1997, a growing number of immunologists and molecular geneticists have made important discoveries about the function of Aire, which is essentially a pleiotropic gene. Aire is one of the functional markers in medullary thymic epithelial cells (mTECs), controlling their differentiation and expression of peripheral tissue antigens (PTAs), mTEC-thymocyte adhesion and the expression of microRNAs, among other functions. With Aire, the immunological tolerance became even more apparent from the molecular genetics point of view. Currently, mTECs represent the most unusual cells because they express almost the entire functional genome but still maintain their identity. Due to the enormous diversity of PTAs, this uncommon gene expression pattern was termed promiscuous gene expression, the interpretation of which is essentially immunological - i.e. it is related to self-representation in the thymus. Therefore, this knowledge is strongly linked to the negative selection of autoreactive thymocytes. In this update, we focus on the most relevant results of Aire as a transcriptional and post-transcriptional controller of PTAs in mTECs, its mechanism of action, and its influence on the negative selection of autoreactive thymocytes as the bases of the induction of central tolerance and prevention of autoimmune diseases. © 2017 John Wiley & Sons Ltd.

  5. Negative reinforcement in applied behavior analysis: an emerging technology.


    Iwata, B A


    Although the effects of negative reinforcement on human behavior have been studied for a number of years, a comprehensive body of applied research does not exist at this time. This article describes three aspects of negative reinforcement as it relates to applied behavior analysis: behavior acquired or maintained through negative reinforcement, the treatment of negatively reinforced behavior, and negative reinforcement as therapy. A consideration of research currently being done in these area...

  6. Negativity towards negative results: a discussion of the disconnect between scientific worth and scientific culture

    Directory of Open Access Journals (Sweden)

    Natalie Matosin


    Full Text Available Science is often romanticised as a flawless system of knowledge building, where scientists work together to systematically find answers. In reality, this is not always the case. Dissemination of results are straightforward when the findings are positive, but what happens when you obtain results that support the null hypothesis, or do not fit with the current scientific thinking? In this Editorial, we discuss the issues surrounding publication bias and the difficulty in communicating negative results. Negative findings are a valuable component of the scientific literature because they force us to critically evaluate and validate our current thinking, and fundamentally move us towards unabridged science.

  7. Negativity towards negative results: a discussion of the disconnect between scientific worth and scientific culture. (United States)

    Matosin, Natalie; Frank, Elisabeth; Engel, Martin; Lum, Jeremy S; Newell, Kelly A


    Science is often romanticised as a flawless system of knowledge building, where scientists work together to systematically find answers. In reality, this is not always the case. Dissemination of results are straightforward when the findings are positive, but what happens when you obtain results that support the null hypothesis, or do not fit with the current scientific thinking? In this Editorial, we discuss the issues surrounding publication bias and the difficulty in communicating negative results. Negative findings are a valuable component of the scientific literature because they force us to critically evaluate and validate our current thinking, and fundamentally move us towards unabridged science.

  8. Negative parenting behavior and childhood oppositional defiant disorder: differential moderation by positive and negative peer regard. (United States)

    Tung, Irene; Lee, Steve S


    Although negative parenting behavior and peer status are independently associated with childhood conduct problems (e.g., oppositional defiant disorder (ODD)), relatively little is known about their interplay, particularly in relation to differentiated measures of positive and negative peer regard. To improve the specificity of the association of negative parenting behavior and peer factors with ODD, we explored the potential interaction of parenting and peer status in a sample of 169 five-to ten-year-old ethnically diverse children with and without attention-deficit/hyperactivity disorder (ADHD) assessed using multiple measures (i.e., rating scales, interview) and informants (i.e., parents, teachers). Controlling for children's age, sex, number of ADHD symptoms, and parents' race-ethnicity, peer acceptance inversely predicted and inconsistent discipline, harsh punishment, and peer rejection were each positively associated with ODD symptom severity. Interactive influences were also evident such that inconsistent discipline and harsh punishment each predicted elevated ODD but only among children experiencing low peer acceptance or high peer rejection. These findings suggest that supportive environments, including peer acceptance, may protect children from negative outcomes associated with inconsistent discipline and harsh punishment. Findings are integrated with theories of social support, and we additionally consider implications for intervention and prevention. © 2013 Wiley Periodicals, Inc.

  9. Hospital nurses' attitudes, negative perceptions, and negative acts regarding workplace bullying. (United States)

    Ma, Shu-Ching; Wang, Hsiu-Hung; Chien, Tsair-Wei


    Workplace bullying is a prevalent problem in today's work places that has adverse effects on both bullying victims and organizations. To investigate the predictors of workplace bullying is an important task to prevent bullying victims of nurses in hospitals. This study aims to explore the relationships among nurses' attitudes, negative perceptions, and negative acts regarding workplace bullying under the framework of the theory of planned behavior (TPB). A total of 811 nurses from three hospitals in Taiwan were surveyed. Nurses' responses to the 201 items of 10 scales were calibrated using Rasch analysis and then subjected to path analysis with partial least-squares structural equation modeling (PLS-SEM). The instrumental attitude was significant predictors of nurses' negative perceptions to be bullied in the workplace. Instead, the other TPB components of subjective norm and perceived behavioral control were not effective predictors of nurses' negative acts regarding workplace bullying. The findings provided hospital nurse management with important implications for prevention of bullying, particularly to them who are tasked with providing safer and more productive workplaces to hospital nurses. Awareness of workplace bullying was recommended to other kinds of workplaces for further studies in future.

  10. Production of intense negative hydrogen beams with polarized nuclei by selective neutralization of cold negative ions (United States)

    Hershcovitch, A.


    A process for selectively neutralizing H/sup -/ ions in a magnetic field to produce an intense negative hydrogen ion beam with spin polarized protons. Characteristic features of the process include providing a multi-ampere beam of H/sup -/ ions that are

  11. Quantification and Negation in Event Semantics

    Directory of Open Access Journals (Sweden)

    Lucas Champollion


    Full Text Available Recently, it has been claimed that event semantics does not go well together with quantification, especially if one rejects syntactic, LF-based approaches to quantifier scope. This paper shows that such fears are unfounded, by presenting a simple, variable-free framework which combines a Neo-Davidsonian event semantics with a type-shifting based account of quantifier scope. The main innovation is that the event variable is bound inside the verbal denotation, rather than at sentence level by existential closure. Quantifiers can then be interpreted in situ. The resulting framework combines the strengths of event semantics and type-shifting accounts of quantifiers and thus does not force the semanticist to posit either a default underlying word order or a syntactic LF-style level. It is therefore well suited for applications to languages where word order is free and quantifier scope is determined by surface order. As an additional benefit, the system leads to a straightforward account of negation, which has also been claimed to be problematic for event-based frameworks.ReferencesBarker, Chris. 2002. ‘Continuations and the nature of quantification’. Natural Language Semantics 10: 211–242., Chris & Shan, Chung-chieh. 2008. ‘Donkey anaphora is in-scope binding’. Semantics and Pragmatics 1: 1–46.Beaver, David & Condoravdi, Cleo. 2007. ‘On the logic of verbal modification’. In Maria Aloni, Paul Dekker & Floris Roelofsen (eds. ‘Proceedings of the Sixteenth Amsterdam Colloquium’, 3–9. Amsterdam, Netherlands: University of Amsterdam.Beghelli, Filippo & Stowell, Tim. 1997. ‘Distributivity and negation: The syntax of each and every’. In Anna Szabolcsi (ed. ‘Ways of scope taking’, 71–107. Dordrecht, Netherlands: Kluwer.Brasoveanu, Adrian. 2010. ‘Modified Numerals as Post-Suppositions’. In Maria Aloni, Harald Bastiaanse, Tikitu de Jager & Katrin Schulz (eds. ‘Logic, Language

  12. Polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes

    DEFF Research Database (Denmark)

    Johansson, Alicia; Calleja, M.; Dimaki, Maria


    A polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes has been designed and realized. Multi-walled carbon nanotubes from aqueous solution have been assembled between two metal electrodes that are separated by 2 mu m and embedded in the polymer cantilever. The entire chip......, except for the metallic electrodes and wiring, was fabricated in the photoresist SU-8. SU-8 allows for an inexpensive, flexible and fast fabrication method, and the cantilever platform provides a hydrophobic surface that should be well suited for nanotube assembly. The device can be integrated in a micro...

  13. Tunnelling with a negative cosmological constant (United States)

    Gibbons, G. W.


    The point of this paper is to see what light new results in hyperbolic geometry may throw on gravitational entropy and whether gravitational entropy is relevant for the quantum origin of the universe. We introduce some new gravitational instantons which mediate the birth from nothing of closed universes containing wormholes and suggest that they may contribute to the density matrix of the universe. We also discuss the connection between their gravitational action and the topological and volumetric entropies introduced in hyperbolic geometry. These coincide for hyperbolic 4-manifolds, and increase with increasing topological complexity of the 4-manifold. We raise the question of whether the action also increases with the topological complexity of the initial 3-geometry, measured either by its 3-volume or its Matveev complexity. We point out, in distinction to the non-supergravity case, that universes with domains of negative cosmological constant separated by supergravity domain walls cannot be born from nothing. Finally we point out that our wormholes provide examples of the type of Perpetual Motion machines envisaged by Frolov and Novikov.

  14. Iodide uptake by negatively charged clay interlayers? (United States)

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng


    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Negative inductance circuits for metamaterial bandwidth enhancement (United States)

    Avignon-Meseldzija, Emilie; Lepetit, Thomas; Ferreira, Pietro Maris; Boust, Fabrice


    Passive metamaterials have yet to be translated into applications on a large scale due in large part to their limited bandwidth. To overcome this limitation many authors have suggested coupling metamaterials to non-Foster circuits. However, up to now, the number of convincing demonstrations based on non-Foster metamaterials has been very limited. This paper intends to clarify why progress has been so slow, i.e., the fundamental difficulty in making a truly broadband and efficient non-Foster metamaterial. To this end, we consider two families of metamaterials, namely Artificial Magnetic Media and Artificial Magnetic Conductors. In both cases, it turns out that bandwidth enhancement requires negative inductance with almost zero resistance. To estimate bandwidth enhancement with actual non-Foster circuits, we consider two classes of such circuits, namely Linvill and gyrator. The issue of stability being critical, both metamaterial families are studied with equivalent circuits that include advanced models of these non-Foster circuits. Conclusions are different for Artificial Magnetic Media coupled to Linvill circuits and Artificial Magnetic Conductors coupled to gyrator circuits. In the first case, requirements for bandwidth enhancement and stability are very hard to meet simultaneously whereas, in the second case, an adjustment of the transistor gain does significantly increase bandwidth.

  16. Negative inductance circuits for metamaterial bandwidth enhancement

    Directory of Open Access Journals (Sweden)

    Avignon-Meseldzija Emilie


    Full Text Available Passive metamaterials have yet to be translated into applications on a large scale due in large part to their limited bandwidth. To overcome this limitation many authors have suggested coupling metamaterials to non-Foster circuits. However, up to now, the number of convincing demonstrations based on non-Foster metamaterials has been very limited. This paper intends to clarify why progress has been so slow, i.e., the fundamental difficulty in making a truly broadband and efficient non-Foster metamaterial. To this end, we consider two families of metamaterials, namely Artificial Magnetic Media and Artificial Magnetic Conductors. In both cases, it turns out that bandwidth enhancement requires negative inductance with almost zero resistance. To estimate bandwidth enhancement with actual non-Foster circuits, we consider two classes of such circuits, namely Linvill and gyrator. The issue of stability being critical, both metamaterial families are studied with equivalent circuits that include advanced models of these non-Foster circuits. Conclusions are different for Artificial Magnetic Media coupled to Linvill circuits and Artificial Magnetic Conductors coupled to gyrator circuits. In the first case, requirements for bandwidth enhancement and stability are very hard to meet simultaneously whereas, in the second case, an adjustment of the transistor gain does significantly increase bandwidth.

  17. TAL effectors specificity stems from negative discrimination.

    Directory of Open Access Journals (Sweden)

    Basile I M Wicky

    Full Text Available Transcription Activator-Like (TAL effectors are DNA-binding proteins secreted by phytopathogenic bacteria that interfere with native cellular functions by binding to plant DNA promoters. The key element of their architecture is a domain of tandem-repeats with almost identical sequences. Most of the polymorphism is located at two consecutive amino acids termed Repeat Variable Diresidue (RVD. The discovery of a direct link between the RVD composition and the targeted nucleotide allowed the design of TAL-derived DNA-binding tools with programmable specificities that revolutionized the field of genome engineering. Despite structural data, the molecular origins of this specificity as well as the recognition mechanism have remained unclear. Molecular simulations of the recent crystal structures suggest that most of the protein-DNA binding energy originates from non-specific interactions between the DNA backbone and non-variable residues, while RVDs contributions are negligible. Based on dynamical and energetic considerations we postulate that, while the first RVD residue promotes helix breaks--allowing folding of TAL as a DNA-wrapping super-helix--the second provides specificity through a negative discrimination of matches. Furthermore, we propose a simple pharmacophore-like model for the rationalization of RVD-DNA interactions and the interpretation of experimental findings concerning shared affinities and binding efficiencies. The explanatory paradigm presented herein provides a better comprehension of this elegant architecture and we hope will allow for improved designs of TAL-derived biotechnological tools.

  18. Do AGN Outflows Support Negative Feedback? (United States)

    Fischer, Travis


    Radiation, winds, and jets of Active Galactic Nuclei (AGN) have been shown to interact with their host galaxy interstellar medium. This radiative or quasar mode of feedback is thought to play a large role in terminating star formation in the galaxy and the accretion of matter onto the central supermassive black hole, accounting for the observed correlation between central black hole and host bulge mass. Recent IFU observations of the nearby Seyfert 2 AGN Mrk 573 have shown that gas radiatively driven by the central engine only travels to radii of approximately 750pc, much smaller than what would be required to evacuate gas from the host bulge. Using archival HST imaging and spectroscopy, we propose to perform similar kinematic analyses on a sample of 23 additional, nearby Seyfert AGN. By generating radiative driving models and comparing them to the observed ionized-gas kinematics in each target, we will determine the maximum outflow radii of the ionized gas and whether these outflows are of scales that would be required in successful negative feedback scenarios.

  19. Decreasing seagrass density negatively influences associated fauna. (United States)

    McCloskey, Rosemary M; Unsworth, Richard K F


    Seagrass meadows globally are disappearing at a rapid rate with physical disturbances being one of the major drivers of this habitat loss. Disturbance of seagrass can lead to fragmentation, a reduction in shoot density, canopy height and coverage, and potentially permanent loss of habitat. Despite being such a widespread issue, knowledge of how such small scale change affects the spatial distribution and abundances of motile fauna remains limited. The present study investigated fish and macro faunal community response patterns to a range of habitat variables (shoot length, cover and density), including individual species habitat preferences within a disturbed and patchy intertidal seagrass meadow. Multivariate analysis showed a measurable effect of variable seagrass cover on the abundance and distribution of the fauna, with species specific preferences to both high and low seagrass cover seagrass. The faunal community composition varied significantly with increasing/decreasing cover. The faunal species composition of low cover seagrass was more similar to sandy control plots than to higher cover seagrass. Shannon Wiener Diversity (H') and species richness was significantly higher in high cover seagrass than in low cover seagrass, indicating increasing habitat value as density increases. The results of this study underline how the impacts of small scale disturbances from factors such as anchor damage, boat moorings and intertidal vehicle use on seagrass meadows that reduce shoot density and cover can impact upon associated fauna. These impacts have negative consequences for the delivery of ecosystem services such as the provision of nursery habitat.

  20. Negative Refractive Index Metasurfaces for Enhanced Biosensing

    Directory of Open Access Journals (Sweden)

    Dragan Tanasković


    Full Text Available In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, or by the adsorption of a thin layer on it, both of which change its properties as a plasmonic guide. We consider various simple forms of plasmonic crystals suitable for this purpose. We start with the basic case of a freestanding, electromagnetically symmetrical plasmonic slab and analyze different ultrathin, multilayer structures, to finally consider some two-dimensional “wallpaper” geometries like split ring resonator arrays and fishnet structures. A part of the text is dedicated to the possibility of multifunctionalization where a metasurface structure is simultaneously utilized both for sensing and for selectivity enhancement. Finally we give an overview of surface-bound intrinsic electromagnetic noise phenomena that limits the ultimate performance of a metasurfaces sensor.