WorldWideScience

Sample records for specific contact resistivity

  1. Silicide-to-silicon specific contact resistance characterization

    NARCIS (Netherlands)

    Stavitski, N.

    2009-01-01

    The performance of Si integrated circuits depends on the transistor drive current. The drive current of a MOS transistor is determined by the total device resistance, which consists of the channel resistance and the parasitic resistances associated with dopant diffusion areas and contacts. It is

  2. Specific Contact Resistance Measurements of Metal Semiconductor-Junctions

    NARCIS (Netherlands)

    Stavitski, N.; van Dal, M.J.H.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

    2006-01-01

    Our research comprises the manufacturing of test structures to characterize the metal-semiconductor junctions with a number of techniques and materials. An extensive subsequent physical and electrical testing of the junctions is carried out. We present our first results on specific

  3. Evaluation of Transmission Line Model Structures for Silicide-to-Silicon Specific Contact Resistance Extraction

    NARCIS (Netherlands)

    Stavitski, N.; van Dal, Mark J.H.; Lauwers, Anne; Vrancken, Christa; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2008-01-01

    In order to measure silicide-to-silicon specific contact resistance �?c, transmission line model (TLM) structures were proposed as attractive candidates for embedding in CMOS processes. We optimized TLM structures for nickel silicide and platinum silicide and evaluated them for various doping levels

  4. Nanoscale metal-InGaAs contacts with ultra-low specific contact resistivity: Improved interfacial quality and extraction methodology

    Science.gov (United States)

    Masudy-Panah, Saeid; Wu, Ying; Lei, Dian; Kumar, Annie; Yeo, Yee-Chia; Gong, Xiao

    2018-01-01

    To enable heterogeneous integration of InGaAs based transistors with Si complementary metal-oxide-semiconductor (CMOS) devices, metal contacts to n+-InGaAs need to have high thermal stability for CMOS process compatibility and ultra-low contact resistance to achieve good device performance. In this work, n+-InGaAs contacts with ultra-low contact resistivity ρc based on refractory metals such as molybdenum (Mo) were realized. Use of refractory metal contacts achieves good thermal stability. An improved process that eliminates oxide between the metal and n+-InGaAs by using an in situ Ar+-plasma treatment prior to metal deposition achieves ultra-low ρc. Furthermore, a nano-scale transmission line method (nano-TLM) structure with significantly reduced parasitic leakage was designed and fabricated to improve the ρc extraction accuracy. The improved test structure introduces a SiO2 isolation layer between Mo and InGaAs outside the active or mesa region to eliminate a parallel leakage path that is present in other nano-TLM structures reported in the literature.

  5. Multiscale electrical contact resistance in clustered contact distribution

    Science.gov (United States)

    Lee, Sangyoung; Cho, Hyun; Jang, Yong Hoon

    2009-08-01

    For contact between rough surfaces of conductors in which a clustered contact spot distribution is dominant through a multiscale process, electrical contact resistance (ECR) is analysed using a smoothed version of Greenwood's model (Jang and Barber 2003 J. Appl. Phys. 94 7215), which is extended to estimate the statistical distribution of contact spots considering the size and the location simultaneously. The application of this statistical method to a contact spot distribution, generated by the finite element method using a fractal surface defined by the random midpoint displacement algorithm, identifies the effect of the clustered contact distribution on ECR, showing that including a finer scale in the fractal contact surface causes the predicted resistance to approach a finite limit. It is also confirmed that the results are close to that of Barber's analogy (Barber 2003 Proc. R. Soc. Lond. A 459 53) regarding incremental stiffness and conductance for elastic contact.

  6. Ultra-low specific contact resistivity (1.4 × 10-9 Ω.cm2) for metal contacts on in-situ Ga-doped Ge0.95Sn0.05 film

    Science.gov (United States)

    Wu, Ying; Luo, Sheng; Wang, Wei; Masudy-Panah, Saeid; Lei, Dian; Liang, Gengchiau; Gong, Xiao; Yeo, Yee-Chia

    2017-12-01

    A heavily Ga-doped Ge0.95Sn0.05 layer was grown on the Ge (100) substrate by molecular beam epitaxy (MBE), achieving an active doping concentration of 1.6 × 1020 cm-3 without the use of ion implantation and high temperature annealing that could cause Sn precipitation or surface segregation. An advanced nano-scale transfer length method was used to extract the specific contact resistivity ρc between the metal and the heavily doped p-Ge0.95Sn0.05 layer. By incorporating Sn into Ge and in-situ Ga doping during the MBE growth, an ultra-low ρc of 1.4 × 10-9 Ω.cm2 was achieved, which is 50% lower than the ρc of p+-Ge control and is also the lowest value obtained for metal/p-type semiconductor contacts.

  7. Evaluation of metal–nanowire electrical contacts by measuring contact end resistance

    International Nuclear Information System (INIS)

    Park, Hongsik; Beresford, Roderic; Xu, Jimmy; Ha, Ryong; Choi, Heon-Jin; Shin, Hyunjung

    2012-01-01

    It is known, but often unappreciated, that the performance of nanowire (NW)-based electrical devices can be significantly affected by electrical contacts between electrodes and NWs, sometimes to the extent that it is really the contacts that determine the performance. To correctly understand and design NW device operation, it is thus important to carefully measure the contact resistance and evaluate the contact parameters, specific contact resistance and transfer length. A four-terminal pattern or a transmission line model (TLM) pattern has been widely used to measure contact resistance of NW devices and the TLM has been typically used to extract contact parameters of NW devices. However, the conventional method assumes that the electrical properties of semiconducting NW regions covered by a metal are not changed after electrode formation. In this study, we report that the conventional methods for contact evaluation can give rise to considerable errors because of an altered property of the NW under the electrodes. We demonstrate that more correct contact resistance can be measured from the TLM pattern rather than the four-terminal pattern and correct contact parameters including the effects of changed NW properties under electrodes can be evaluated by using the contact end resistance measurement method. (paper)

  8. Sheet resistance under Ohmic contacts to AlGaN/GaN heterostructures

    NARCIS (Netherlands)

    Hajlasz, M.; Donkers, J.J.T.M.; Sque, S.J.; Heil, S.B.S.; Gravesteijn, Dirk J; Rietveld, F.J.R.; Schmitz, Jurriaan

    2014-01-01

    For the determination of specific contact resistance in semiconductor devices, it is usually assumed that the sheet resistance under the contact is identical to that between the contacts. This generally does not hold for contacts to AlGaN/GaN structures, where an effective doping under the contact

  9. Determination of Thermal Contact Resistances for Small TENV Electrical Machine

    OpenAIRE

    Olfa MEKSI; Mohd Azri Hizami RASID; Alejandro OSPINA; Vincent LANFRANCHI

    2016-01-01

    In this paper, a thermal study of Synchronous Reluctant motor is proposed. A specific experimental method is applied in order to identify the thermal parameters, this method focus on the study of contact resistances and total thermal capacity. Generally, in the classical thermal modeling, the thermal contact resistance (TCR) is estimated by empirical values and the thermal capacities are calculated by analytical solutions. The originality of the proposed model is based on the complementarity ...

  10. Resistance switching in silver - manganite contacts

    International Nuclear Information System (INIS)

    Gomez-Marlasca, F; Levy, P

    2009-01-01

    We investigate the electric pulse induced resistance switching in a transition metal oxide-metal contact at room temperature - a non volatile, reversible and multilevel memory device. Using a simple multiterminal configuration, we find that the complementary effect -in which the contact resistance of each pulsed electrode displays variations of opposite sign- is strongly influenced by the history of the pulsing procedure. Loops performed by varying the magnitude and sign of the stimulus at each pulsed electrode allow to disentangle their sole contribution at different stages of the process. Electromigration of oxygen ions and vacancies is discussed as participating at the core of the underlying mechanisms for resistance switching.

  11. Stable and low contact resistance electrical contacts for high temperature SiGe thermoelectric generators

    KAUST Repository

    Zhang, Bo

    2018-04-14

    The thermal stability and contact resistance of TaAlN thin films as electrical contacts to SiGe thermoelectric elements are reported. We demonstrate that a sharp interface is maintained after the device annealed at 800°C for over 100h, indicating that no interdiffusion takes place between TaAlN and SiGe. A specific contact resistivity of (2.1±1.3)×10−6Ω-cm2 for p-type SiGe and (2.8±1.6)×10−5 Ω-cm2 for n-type SiGe is demonstrated after the high temperature annealing. These results show that TaAlN is a promising contact material for high temperature thermoelectrics such as SiGe.

  12. Reduced contact resistance in top-contact organic field-effect transistors by interface contact doping

    Science.gov (United States)

    Hou, Ji-Ling; Kasemann, Daniel; Widmer, Johannes; Günther, Alrun A.; Lüssem, Björn; Leo, Karl

    2016-03-01

    Emerging organic integrated electronics require capability of high speed and the compatibility with high-resolution structuring processes such as photolithography. When downscaling the channel length, the contact resistance is known to limit the performance of the short channel devices. In this report, orthogonal photolithography is used for the patterning of the source/drain electrodes of the organic field-effect transistors (OFETs) as well as the interface dopant insertion layers for further modifications of the contact resistance. Bottom-gate top-contact pentacene OFETs with different thicknesses of the p-dopant 2,2'-(perfluoronaphthalene-2,6-diylidene)dimalononitrile under the Au electrodes show a significant decrease in threshold voltage from -2.2 V to -0.8 V and in contact resistance from 55 k Ω cm to 10 k Ω cm by adding a 1 nm thin dopant interlayer. The influence of doping on charge carrier injection is directly visible in the temperature-dependent output characteristics and a charge-transfer activation energy of ˜20 meV is obtained. Our results provide a systematic study of interface contact doping and also show the connection between interface contact doping and improved charge carrier injection by the activation of charge transfer process.

  13. Direct measurement of graphene contact resistivity to pre-deposited metal in buried contact test structure

    KAUST Repository

    Qaisi, Ramy M.

    2013-08-01

    We demonstrate a buried contact based novel test structure for direct contact resistivity measurement of graphene-metal interfaces. We also observe excellent contact resistivity 1 μO-cm2 without any additional surface modification suggesting that the intrinsic Au-graphene contact is sufficient for achieving devices with low contact resistance. The chemical mechanical polishing less test structure and data described herein highlights an ideal methodology for systematic screening and engineering of graphene-metal contact resistivity to enable low power high speed carbon electronics. © 2013 IEEE.

  14. Low contact resistance in epitaxial graphene devices for quantum metrology

    Energy Technology Data Exchange (ETDEWEB)

    Yager, Tom, E-mail: yager@chalmers.se, E-mail: ywpark@snu.ac.kr; Lartsev, Arseniy; Lara-Avila, Samuel; Kubatkin, Sergey [Department of Microtechnology and Nanoscience, Chalmers University of Technology Göteborg, S-412 96 (Sweden); Cedergren, Karin [School of Physics, University of New South Wales, Sydney, NSW-2052 (Australia); Yakimova, Rositsa [Department of Physics, Chemistry and Biology (IFM), Linköping University Linköping, S-581 83 (Sweden); Panchal, Vishal; Kazakova, Olga [National Physical Laboratory, Teddington, TW11 0LW (United Kingdom); Tzalenchuk, Alexander [National Physical Laboratory, Teddington, TW11 0LW (United Kingdom); Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX (United Kingdom); Kim, Kyung Ho; Park, Yung Woo, E-mail: yager@chalmers.se, E-mail: ywpark@snu.ac.kr [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-08-15

    We investigate Ti/Au contacts to monolayer epitaxial graphene on SiC (0001) for applications in quantum resistance metrology. Using three-terminal measurements in the quantum Hall regime we observed variations in contact resistances ranging from a minimal value of 0.6 Ω up to 11 kΩ. We identify a major source of high-resistance contacts to be due bilayer graphene interruptions to the quantum Hall current, whilst discarding the effects of interface cleanliness and contact geometry for our fabricated devices. Moreover, we experimentally demonstrate methods to improve the reproducibility of low resistance contacts (<10 Ω) suitable for high precision quantum resistance metrology.

  15. Low contact resistance in epitaxial graphene devices for quantum metrology

    Directory of Open Access Journals (Sweden)

    Tom Yager

    2015-08-01

    Full Text Available We investigate Ti/Au contacts to monolayer epitaxial graphene on SiC (0001 for applications in quantum resistance metrology. Using three-terminal measurements in the quantum Hall regime we observed variations in contact resistances ranging from a minimal value of 0.6 Ω up to 11 kΩ. We identify a major source of high-resistance contacts to be due bilayer graphene interruptions to the quantum Hall current, whilst discarding the effects of interface cleanliness and contact geometry for our fabricated devices. Moreover, we experimentally demonstrate methods to improve the reproducibility of low resistance contacts (<10 Ω suitable for high precision quantum resistance metrology.

  16. Abnormal contact resistance reduction of bonded copper interconnects in three-dimensional integration during current stressing

    Science.gov (United States)

    Chen, K. N.; Tan, C. S.; Fan, A.; Reif, R.

    2005-01-01

    Bonded copper interconnects were stressed with current to measure the specific contact resistance. For bonded copper interconnects without a prebonding HCl clean, the corresponding specific contact resistance did not change while increasing the stress current. However, for some interconnects with the prebonding HCl clean, an abnormal contact resistance reduction was observed during the increase of the stress current. The rise of temperature at the bonding interface area due to Joule heating under high current density may have caused the decrease of contact resistance. This behavior may be one option for quality enhancement in 3D integration at low temperature.

  17. Testing and Modeling of Contact Problems in Resistance Welding

    DEFF Research Database (Denmark)

    Song, Quanfeng

    As a part of the efforts towards a professional and reliable numerical tool for resistance welding engineers, this Ph.D. project is dedicated to refining the numerical models related to the interface behavior. An FE algorithm for the contact problems in resistance welding has been developed...... in this work, dealing with the coupled mechanical-electrical-thermal contact problems. The penalty method is used to impose the contact conditions in the electrical and thermal contact, as well as frictionless contact and sticking contact in the mechanical model. A node-segment contact element is the basis...

  18. Simplistic graphene transfer process and its impact on contact resistance

    KAUST Repository

    Ghoneim, Mohamed T.

    2013-05-09

    Chemical vapor deposition based graphene grown on copper foil is attractive for electronic applications owing to its reliable growth process, large area coverage, and relatively defect free nature. However, transfer of the synthesized graphene to host substrate for subsequent device fabrication is extremely sensitive and can impact ultimate performance. Although ultra-high mobility is graphene\\'s most prominent feature, problems with high contact resistance have severely limited its true potential. Therefore, we report a simple poly-(methyl methacrylate) based transfer process without post-annealing to achieve specific contact resistivity of 3.8 × 10−5 Ω cm2 which shows 80% reduction compared to previously reported values.

  19. Effect of Contact Pressure on the Resistance Contact Value and Temperature Changes in Copper Busbar Connection

    Directory of Open Access Journals (Sweden)

    Agus Risdiyanto

    2012-12-01

    Full Text Available This paper discussed the influence of tightness or contacts pressure on copper busbar joints to determine changes in the value of the initial contact resistance and the maximum temperature at the joint due to high current load. The test sample was copper busbar 3 x 30 mm with configuration of bolted overlapping joint. Increasing contact pressure at the joint was measured to find out its effect on the value of contact resistance. The applied pressure was 6 to 36 MPa. Procedure of contact resistance measurement refer to the ASTM B539 standard using four-wire method. The sample subsequently loaded with the current of 350 A for 60 minutes and the maximum temperature at the joint was measured. The result showed that increasing contact pressure at the busbar joint will reduce the contact resistance and maximum temperature. The increase of contact pressure from 6 to 30 MPa causes decreasing contact resistance from 16 μΩ to 11 μΩ. Further increasing of contact pressure more than 30 MPa did not affect the contact resistance significantly. The lowest temperatur of busbar joint of 54°C was reached at a contact pressure of 36 Mpa.

  20. Temperature dependence of contact resistance at metal/MWNT interface

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang-Eui; Moon, Kyoung-Seok; Sohn, Yoonchul, E-mail: yoonchul.son@samsung.com [Materials Research Center, Samsung Advanced Institute of Technology, Samsung Electronics, Suwon 443-803 (Korea, Republic of)

    2016-07-11

    Although contact resistance of carbon nanotube (CNT) is one of the most important factors for practical application of electronic devices, a study regarding temperature dependence on contact resistance of CNTs with metal electrodes has not been found. Here, we report an investigation of contact resistance at multiwalled nanotube (MWNT)/Ag interface as a function of temperature, using MWNT/polydimethylsiloxane (PDMS) composite. Electrical resistance of MWNT/PDMS composite revealed negative temperature coefficient (NTC). Excluding the contact resistance with Ag electrode, the NTC effect became less pronounced, showing lower intrinsic resistivity with the activation energy of 0.019 eV. Activation energy of the contact resistance of MWNT/Ag interface was determined to be 0.04 eV, two times larger than that of MWNT-MWNT network. The increase in the thermal fluctuation assisted electron tunneling is attributed to conductivity enhancement at both MWNT/MWNT and MWNT/Ag interfaces with increasing temperature.

  1. Bias dependent specic contact resistance of phase change material to metal contacts

    NARCIS (Netherlands)

    Roy, Deepu; in 't Zandt, Micha; Wolters, Robertus A.M.

    2010-01-01

    Knowledge of contact resistance of phase change materials (PCM) to metal electrodes is important for scaling, device modeling and optimization of phase change random access memory (PCRAM) cells. In this article, we report the systematic determination of the speci_c contact resistance (_c) with

  2. Contact resistance evolution of highly cycled, lightly loaded micro-contacts

    Science.gov (United States)

    Stilson, Christopher; Coutu, Ronald

    2014-03-01

    Reliable microelectromechanical systems (MEMS) switches are critical for developing high performance radio frequency circuits like phase shifters. Engineers have attempted to improve reliability and lifecycle performance using novel contact metals, unique mechanical designs and packaging. Various test fixtures including: MEMS devices, atomic force microscopes (AFM) and nanoindentors have been used to collect resistance and contact force data. AFM and nanoindentor test fixtures allow direct contact force measurements but are severely limited by low resonance sensors, and therefore low data collection rates. This paper reports the contact resistance evolution results and fabrication of thin film, sputtered and evaporated gold, micro-contacts dynamically tested up to 3kHz. The upper contact support structure consists of a gold surface micromachined, fix-fix beam designed with sufficient restoring force to overcome adhesion. The hemisphere-upper and planar-lower contacts are mated with a calibrated, external load resulting in approximately 100μN of contact force and are cycled in excess of 106 times or until failure. Contact resistance is measured, in-situ, using a cross-bar configuration and the entire apparatus is isolated from external vibration and housed in an enclosure to minimize contamination due to ambient environment. Additionally, contact cycling and data collection are automated using a computer and LabVIEW. Results include contact resistance measurements of 6 and 8 μm radius contact bumps and lifetime testing up to 323.6 million cycles.

  3. Using TLM principles to determine MOSFET contact and parasitic resistance

    Science.gov (United States)

    Reeves, Geoffrey K.; Harrison, H. Barry

    1997-08-01

    Transmission Line Model (TLM) networks are commonly used to model planar metal-semiconductor ohmic contacts. Multiple layer contacts such as non-alloyed {n +}/{n}, heterojunction and metal-silicide-silicon contacts can also be analyzed using a Tri-Layer TLM (TLTLM) network. In this article, two and three layer contact structures are combined using the appropriate TLM models in order to electrically model the gate-drain/source extension and drain/source contact region of a MOSFET. Important device properties such as contact and parasitic resistance can thus be derived for various device structures in terms of the geometrical and material parameters used in the TLM model. The developed model is used to give an example calculation of the parasitic resistance in the gate-drain extension and the resistance of the ohmic contact.

  4. Beta atomic contacts: identifying critical specific contacts in protein binding interfaces.

    Science.gov (United States)

    Liu, Qian; Kwoh, Chee Keong; Hoi, Steven C H

    2013-01-01

    Specific binding between proteins plays a crucial role in molecular functions and biological processes. Protein binding interfaces and their atomic contacts are typically defined by simple criteria, such as distance-based definitions that only use some threshold of spatial distance in previous studies. These definitions neglect the nearby atomic organization of contact atoms, and thus detect predominant contacts which are interrupted by other atoms. It is questionable whether such kinds of interrupted contacts are as important as other contacts in protein binding. To tackle this challenge, we propose a new definition called beta (β) atomic contacts. Our definition, founded on the β-skeletons in computational geometry, requires that there is no other atom in the contact spheres defined by two contact atoms; this sphere is similar to the van der Waals spheres of atoms. The statistical analysis on a large dataset shows that β contacts are only a small fraction of conventional distance-based contacts. To empirically quantify the importance of β contacts, we design βACV, an SVM classifier with β contacts as input, to classify homodimers from crystal packing. We found that our βACV is able to achieve the state-of-the-art classification performance superior to SVM classifiers with distance-based contacts as input. Our βACV also outperforms several existing methods when being evaluated on several datasets in previous works. The promising empirical performance suggests that β contacts can truly identify critical specific contacts in protein binding interfaces. β contacts thus provide a new model for more precise description of atomic organization in protein quaternary structures than distance-based contacts.

  5. Cross-Bridge Kelvin resistor structures for reliable measurement of low contact resistances and contact interface characterization

    NARCIS (Netherlands)

    Stavitski, N.; Klootwijk, J.H.; van Zeijl, H.W.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2009-01-01

    The parasitic factors that strongly influence the measurement accuracy of Cross-Bridge Kelvin Resistor (CBKR) structures for low specific contact resistances (�?�c) have been extensively discussed during last few decades and the minimum of the �?�c value, which could be accurately extracted, was

  6. The effect of electrode contact resistance and capacitive coupling on Complex Resistivity measurements

    DEFF Research Database (Denmark)

    Ingeman-Nielsen, Thomas

    2006-01-01

    The effect of electrode contact resistance and capacitive coupling on complex resistivity (CR) measurements is studied in this paper. An equivalent circuit model for the receiver is developed to describe the effects. The model shows that CR measurements are severely affected even at relatively lo...... with the contact resistance artificially increased by resistors. The results emphasize the importance of keeping contact resistance low in CR measurements....

  7. Physical model of the contact resistivity of metal-graphene junctions

    Energy Technology Data Exchange (ETDEWEB)

    Chaves, Ferney A., E-mail: ferneyalveiro.chaves@uab.cat; Jiménez, David [Departament d' Enginyeria Electrònica, Escola d' Enginyeria, Universitat Autònoma de Barcelona, Campus UAB, 08193 Bellaterra, Barcelona (Spain); Cummings, Aron W. [ICN2–Institut Català de Nanociència i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain); Roche, Stephan [ICN2–Institut Català de Nanociència i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain); ICREA, Institució Catalana de Recerca i Estudis Avançats, 08070 Barcelona (Spain)

    2014-04-28

    While graphene-based technology shows great promise for a variety of electronic applications, including radio-frequency devices, the resistance of the metal-graphene contact is a technological bottleneck for the realization of viable graphene electronics. One of the most important factors in determining the resistance of a metal-graphene junction is the contact resistivity. Despite the large number of experimental works that exist in the literature measuring the contact resistivity, a simple model of it is still lacking. In this paper, we present a comprehensive physical model for the contact resistivity of these junctions, based on the Bardeen Transfer Hamiltonian method. This model unveils the role played by different electrical and physical parameters in determining the specific contact resistivity, such as the chemical potential of interaction, the work metal-graphene function difference, and the insulator thickness between the metal and graphene. In addition, our model reveals that the contact resistivity is strongly dependent on the bias voltage across the metal-graphene junction. This model is applicable to a wide variety of graphene-based electronic devices and thus is useful for understanding how to optimize the contact resistance in these systems.

  8. Physical model of the contact resistivity of metal-graphene junctions

    International Nuclear Information System (INIS)

    Chaves, Ferney A.; Jiménez, David; Cummings, Aron W.; Roche, Stephan

    2014-01-01

    While graphene-based technology shows great promise for a variety of electronic applications, including radio-frequency devices, the resistance of the metal-graphene contact is a technological bottleneck for the realization of viable graphene electronics. One of the most important factors in determining the resistance of a metal-graphene junction is the contact resistivity. Despite the large number of experimental works that exist in the literature measuring the contact resistivity, a simple model of it is still lacking. In this paper, we present a comprehensive physical model for the contact resistivity of these junctions, based on the Bardeen Transfer Hamiltonian method. This model unveils the role played by different electrical and physical parameters in determining the specific contact resistivity, such as the chemical potential of interaction, the work metal-graphene function difference, and the insulator thickness between the metal and graphene. In addition, our model reveals that the contact resistivity is strongly dependent on the bias voltage across the metal-graphene junction. This model is applicable to a wide variety of graphene-based electronic devices and thus is useful for understanding how to optimize the contact resistance in these systems

  9. Contact Resistance Evolution and Degradation of Highly Cycled Micro-Contacts

    Science.gov (United States)

    2014-03-27

    to predict accurate and complex calculations of circular and rectangular contact spreading resistances [17]. The method was to solve the three... mico -contact lasted twice as long as the the contacts with the softer Au as the cathode. On 96 the RuO2 10% the same conclusion can be drawn where the...Hoppe and W. Pilz, "Microfabrication of complex surface topographies using grey-tone lithography," Sensors and Actuators A: Physical, vol. 46, pp

  10. Contact Resistance Evolution and Degradation of Highly Cycled

    Science.gov (United States)

    2014-03-27

    to predict accurate and complex calculations of circular and rectangular contact spreading resistances [17]. The method was to solve the three... mico -contact lasted twice as long as the the contacts with the softer Au as the cathode. On 96 the RuO2 10% the same conclusion can be drawn where the...Hoppe and W. Pilz, "Microfabrication of complex surface topographies using grey-tone lithography," Sensors and Actuators A: Physical, vol. 46, pp

  11. Low resistive edge contacts to CVD-grown graphene using a CMOS compatible metal

    Energy Technology Data Exchange (ETDEWEB)

    Shaygan, Mehrdad; Otto, Martin; Sagade, Abhay A.; Neumaier, Daniel [Advanced Microelectronic Center Aachen, AMO GmbH, Aachen (Germany); Chavarin, Carlos A. [Lehrstuhl Werkstoffe der Elektrotechnik, Duisburg-Essen Univ., Duisburg (Germany); Innovations for High Performance Microelectronics, IHP GmbH, Frankfurt (Oder) (Germany); Bacher, Gerd; Mertin, Wolfgang [Lehrstuhl Werkstoffe der Elektrotechnik, Duisburg-Essen Univ., Duisburg (Germany)

    2017-11-15

    The exploitation of the excellent intrinsic electronic properties of graphene for device applications is hampered by a large contact resistance between the metal and graphene. The formation of edge contacts rather than top contacts is one of the most promising solutions for realizing low ohmic contacts. In this paper the fabrication and characterization of edge contacts to large area CVD-grown monolayer graphene by means of optical lithography using CMOS compatible metals, i.e. Nickel and Aluminum is reported. Extraction of the contact resistance by Transfer Line Method (TLM) as well as the direct measurement using Kelvin Probe Force Microscopy demonstrates a very low width specific contact resistance down to 130 Ωμm. The contact resistance is found to be stable for annealing temperatures up to 150 C enabling further device processing. Using this contact scheme for edge contacts, a field effect transistor based on CVD graphene with a high transconductance of 0.63 mS/μm at 1 V bias voltage is fabricated. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. An Experimental Study of the Electrical Contact Resistance in Resistance Welding

    DEFF Research Database (Denmark)

    Song, Quanfeng; Zhang, Wenqi; Bay, Niels

    2005-01-01

    Electrical contact resistance is of critical importance in resistance welding. In this article, the contact resistance is experimentally investigated for welding mild steel, stainless steel, and aluminum to themselves. A parametric study was carried out on a Gleeble® machine, investigating...

  13. Establishing an upper bound on contact resistivity of ohmic contacts to n-GaN nanowires

    International Nuclear Information System (INIS)

    Blanchard, Paul; Bertness, Kris A; Harvey, Todd; Sanford, Norman

    2014-01-01

    Contact resistivity ρ c is an important figure of merit in evaluating and improving the performance of electronic and optoelectronic devices. Due to the small size, unique morphology, and uncertain transport properties of semiconductor nanowires (NWs), measuring ρ c of contacts to NWs can be particularly challenging. In this work, Si-doped n-GaN NWs were grown by molecular beam epitaxy. Four-contact structures with 20 nm Ti/200 nm Al contacts were fabricated on individual NWs by photolithography, and the contacts were annealed to achieve ohmic behavior. Two-point resistances R 23  and four-point collinear resistances R 23collinear  were measured between the middle two contacts on each NW. These resistances were then modeled by taking into account the non-uniform distribution of current flow along the length of each contact. Contrary to the assumption that the resistance difference R 23 −R 23collinear  is equal to the total contact resistance R c , the distributed-current-flow contact model shows that R 23 −R 23collinear  ≪ R c when ρ c is sufficiently small. Indeed, the measured R 23 −R 23collinear  was so small in these devices that it was within the measurement uncertainty, meaning that it was not possible to directly calculate ρ c from these data. However, it was possible to calculate an upper bound on ρ c for each device based on the largest possible value of R 23 −R 23collinear . In addition, we took into account the large uncertainties in the NW transport properties by numerically maximizing ρ c with respect to the uncertainty range of each measured and assumed parameter in the contact model. The resulting upper limits on ρ c ranged from 4.2 × 10 −6  to 7.6 × 10 −6  Ω cm 2 , indicating that 20 nm Ti/200 nm Al is a good choice of ohmic contact for moderately-doped n-GaN NWs. The measurement and numerical analysis demonstrated here offer a general approach to modeling ohmic contact resistivity via NW four

  14. Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach

    Directory of Open Access Journals (Sweden)

    Luan Pan

    2014-07-01

    Full Text Available Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument.

  15. Vertical soil profiling using a galvanic contact resistivity scanning approach.

    Science.gov (United States)

    Pan, Luan; Adamchuk, Viacheslav I; Prasher, Shiv; Gebbers, Robin; Taylor, Richard S; Dabas, Michel

    2014-07-23

    Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep) soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument.

  16. Mathematical Modeling of Contact Resistance in Silicon Photovoltaic Cells

    KAUST Repository

    Black, J. P.

    2013-10-22

    In screen-printed silicon-crystalline solar cells, the contact resistance of a thin interfacial glass layer between the silicon and the silver electrode plays a limiting role for electron transport. We analyze a simple model for electron transport across this layer, based on the driftdiffusion equations. We utilize the size of the current/Debye length to conduct asymptotic techniques to simplify the model; we solve the model numerically to find that the effective contact resistance may be a monotonic increasing, monotonic decreasing, or nonmonotonic function of the electron flux, depending on the values of the physical parameters. © 2013 Society for Industrial and Applied Mathematics.

  17. Resistive switching in Ag-TiO{sub 2} contacts

    Energy Technology Data Exchange (ETDEWEB)

    Ghenzi, N., E-mail: ghenzi@cnea.gov.ar [Gerencia de Investigacion y Aplicaciones, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina); Stoliar, P. [Gerencia de Investigacion y Aplicaciones, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Campus Migueletes, UNSAM, Pcia. de Buenos Aires (Argentina); Fuertes, M.C. [Gerencia Quimica, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina); Marlasca, F.G.; Levy, P. [Gerencia de Investigacion y Aplicaciones, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina)

    2012-08-15

    We study the electric pulse induced resistance switching of TiO{sub 2}-Ag contacts at room temperature, exploring both unipolar and bipolar switching modes. Initially we observed unipolar response. After hundred pulsing cycles the unipolar switching response vanishes but the device can still be operated in bipolar switching regime. The underlying mechanism for resistance switching is modeled in terms of formation and rupture of filament, and movement of oxygen vacancies.

  18. Contact resistance and stability study for Au, Ti, Hf and Ni contacts on thin-film Mg2Si

    KAUST Repository

    Zhang, Bo

    2016-12-28

    We present a detailed study of post-deposition annealing effects on contact resistance of Au, Ti, Hf and Ni electrodes on Mg2Si thin films. Thin-film Mg2Si and metal contacts were deposited using magnetron sputtering. Various post-annealing temperatures were studied to determine the thermal stability of each contact metal. The specific contact resistivity (SCR) was determined using the Cross Bridge Kelvin Resistor (CBKR) method. Ni contacts exhibits the best thermal stability, maintaining stability up to 400 °C, with a SCR of approximately 10−2 Ω-cm2 after annealing. The increased SCR after high temperature annealing is correlated with the formation of a Mg-Si-Ni mixture identified by cross-sectional scanning transmission electron microscopy (STEM) characterization, X-ray diffraction characterization (XRD) and other elemental analyses. The formation of this Mg-Si-Ni mixture is attributed to Ni diffusion and its reaction with the Mg2Si film.

  19. Transmission of methicillin-resistant Staphylococcus aureus to household contacts

    NARCIS (Netherlands)

    F.P.N. Mollema (Femke); J.H. Richardus (Jan Hendrik); M.D. Behrendt (Myra); N. Vaessen (Norbert); W. Lodder; W. Hendriks; H.A. Verbrugh (Henri); A. Voss (Andreas)

    2010-01-01

    textabstractThe frequency of and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) transmission from a MRSA index person to household contacts were assessed in this prospective study. Between January 2005 and December 2007, 62 newly diagnosed MRSA index persons (46 patients and 16

  20. Cross-bidge Kelvin resistor (CBKR) structures for measurement of low contact resistances

    NARCIS (Netherlands)

    Stavitski, N.; Klootwijk, J.H.; van Zeijl, H.W.; Boksteen, B.K.; Boksteen, B.K.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2007-01-01

    A convenient test structure for measurement of the specific contact resistance (�?c) of metal-semiconductor junctions is the CBKR structure. During last few decades the parasitic factors which may strongly affect the measurements accuracy for �?c < 10-6 Ω • cm2 have been sufficiently discussed and

  1. A study of cross-bridge kelvin resistor structures for reliable measurement of low contact resistances

    NARCIS (Netherlands)

    Stavitski, N.; Klootwijk, J.H.; van Zeijl, H.W.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2008-01-01

    The parasitic factors that strongly influence the measurement accuracy of Cross-Bridge Kelvin Resistor (CBKR) structures for low specific contact resistances (�?c) have been extensively discussed during last few decades and the minimum of the �?c value, which could be accurately extracted, was

  2. Determining the specific electric resistance of rock

    Energy Technology Data Exchange (ETDEWEB)

    Persad' ko, V.Ia.

    1982-01-01

    Data are presented on perfecting the method of laboratory determination of the specific electric resistance of a rock formation. The average error in determining the specific electric resistance of the core at various locations is no more than two percent with low resistance values (2-5 ohms).

  3. Does allergen-specific immunotherapy induce contact allergy to aluminium?

    Science.gov (United States)

    Netterlid, Eva; Hindsén, Monica; Siemund, Ingrid; Björk, Jonas; Werner, Sonja; Jacobsson, Helene; Güner, Nuray; Bruze, Magnus

    2013-01-01

    Persistent, itching nodules have been reported to appear at the injection site after allergen-specific immuno-therapy with aluminium-precipitated antigen extract, occasionally in conjunction with contact allergy to aluminium. This study aimed to quantify the development of contact allergy to aluminium during allergen-specific immunotherapy. A randomized, controlled, single-blind multicentre study of children and adults entering allergen-specific immunotherapy was performed using questionnaires and patch-testing. A total of 205 individuals completed the study. In the 3 study groups all subjects tested negative to aluminium before allergen-specific immunotherapy and 4 tested positive after therapy. In the control group 4 participants tested positive to aluminium. Six out of 8 who tested positive also had atopic dermatitis. Positive test results were found in 5/78 children and 3/127 adults. Allergen-specific immunotherapy was not shown to be a risk factor for contact allergy to aluminium. Among those who did develop aluminium allergy, children and those with atopic dermatitis were more highly represented.

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

    DEFF Research Database (Denmark)

    Häfliger, Daniel; Boisen, Anja

    2005-01-01

    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...

  5. Effect of surfaces similarity on contact resistance of fractal rough surfaces under cyclic loading

    Science.gov (United States)

    Gao, Yuanwen; Liu, Limei; Ta, Wurui; Song, Jihua

    2018-03-01

    Although numerous studies have shown that contact resistance depends significantly on roughness and fractal dimension, it remains elusive how they affect contact resistance between rough surfaces. The interface similarity index is first proposed to describe the similarity of the contact surfaces, which gives a good indication of the actual contact area between surfaces. We reveal that the surfaces' similarity be an origin of contact resistance variation. The cyclic loading can increase the contact stiffness, and the contact stiffness increases with the increase of the interface similarity index. These findings explain the mechanism of surface roughness and fractal dimension on contact resistance, and also provide reference for the reliability design of the electrical connection.

  6. Z-Pinch Wire-Electrode Contact Resistance Studies Using Weighted and Soft Metal Gasket Contacts*

    Science.gov (United States)

    Gomez, M. R.; Zier, J. C.; Thurtell, A. F.; French, D. M.; Gilgenbach, R. M.; Tang, W.; Lau, Y. Y.

    2008-11-01

    The contact made between z-pinch wires and electrodes has a significant effect on both the energy deposited in the wires and the uniformity of the expansion profile of the wires. We have shown that using soft metal gaskets can improve wire-electrode contact significantly over typical weighted contacts. Images of wire expansion profile and wire plasma emission will be presented for single and double wire shots on a 16 kA, 100 kV 4-stage Marx bank with 150 ns risetime. Bench resistance measurements for aluminum, stainless steel, and tungsten wires with diameters ranging from 7.5 um to 30 um will be presented. These measurements utilized both soft metal gasket contacts (gaskets include: indium, silver, aluminum, tin, and lead) and double-ended wire weight contacts (weights ranged from 0.4 g to 1.9 g). *This research was supported by U. S. DoE through Sandia National Laboratories award document numbers 240985, 768225, 790791 and 805234 to the University of Michigan. MRG supported by NNSA Fellowship and JCZ supported by NPSC Fellowship sponsored by Sandia National Labs.

  7. Contact Resistance of Ceramic Interfaces Between Materials Used for Solid Oxide Fuel Cell Applications

    DEFF Research Database (Denmark)

    Koch, Søren

    The contact resistance can be divided into two main contributions. The small area of contact between ceramic components results in resistance due to current constriction. Resistive phases or potential barriers at the interface result in an interface contribution to the contact resistance, which may...... be smaller or larger than the constriction resistance. The contact resistance between pairs of three different materials were analysed (stron-tium doped lanthanum manganite, yttria stabilised zirconia and strontium and nickel doped lanthanum cobaltite), and the effects of temperature, atmosphere......, polarisation and mechanical load on the contact resistance were investigated. The investigations revealed that the mechanical load of a ceramic contact has a high influence on the contact resistance, and generally power law dependence between the contact resistance and the mechanical load was found...

  8. Contact resistance characteristics of Ag–SnO2 contact materials with high SnO2 content

    International Nuclear Information System (INIS)

    Wang, Jun; Tie, Shengnian; Kang, Yongqiang; Wang, Yaping

    2015-01-01

    Highlights: • Surface morphologies of arc eroded Ag–SnO 2 samples were stable and uniform. • Contact resistance of Ag–30SnO 2 samples increased by 33% and stabilize in 5 mΩ. • Contact resistance can be reduced significantly by increasing the contact force. • The present results provide an effective way to low and stable contact resistance. - Abstract: The contact resistance and surface morphologies characteristics of Ag–SnO 2 contact materials with high SnO 2 content was investigated in make-and-break operations. The microstructure and arc eroded surface morphologies of Ag–SnO 2 samples were researched by Scanning Electron Microscopy (SEM). The surface profiles and average surface roughness S a of arc eroded Ag–SnO 2 samples were also analyzed by Scanning Laser Microscope (SLM) 3D surface technique. With the SnO 2 content increase from 15 wt.% to 30 wt.%, it was found that contact resistance of Ag–SnO 2 materials increased by 33% and stabilize in 5 mΩ when contact force over than 70 N. The surface morphologies of arc eroded Ag–SnO 2 samples were stable and uniform compared with the original samples. The theoretical analysis and experimental results of contact resistance characteristic indicated that contact force is the predominant factor for the contact resistances of Ag–SnO 2 materials with high SnO 2 content and contact resistance of high SnO 2 content Ag–SnO 2 materials can be reduced significantly by increasing the contact force

  9. CORROSION RESISTANCE OF ALUMINUM CANS IN CONTACT WITH BEER

    Directory of Open Access Journals (Sweden)

    Luiza Esteves

    2015-07-01

    Full Text Available Aluminum cans with an organic coating are used in Brazil as packaging for carbonated beverages (soft drinks, beer, which act as electrolyte solutions. These electrolytes, in contact with the inner metal can, initiate a corrosion process of aluminum. The presence of metallic ions can change the flavor of the beverage, compromising the product quality. This work aims to evaluate the corrosion resistance of aluminum in beer environment using the technique of Electrochemical Impedance Spectroscopy (EIS. The Scanning Electron Microscopy (SEM and the Energy Dispersive Spectroscopy (EDS were used to evaluate the metal surface. Two batches with different coating thickness were analyzed for the same date of manufacture. The electrolyte resistance and the aluminum charge transfer resistance in beer varied depending on the batch analyzed.

  10. Method of separate determination of high-ohmic sample resistance and contact resistance

    Directory of Open Access Journals (Sweden)

    Vadim A. Golubiatnikov

    2015-09-01

    Full Text Available A method of separate determination of two-pole sample volume resistance and contact resistance is suggested. The method is applicable to high-ohmic semiconductor samples: semi-insulating gallium arsenide, detector cadmium-zinc telluride (CZT, etc. The method is based on near-contact region illumination by monochromatic radiation of variable intensity from light emitting diodes with quantum energies exceeding the band gap of the material. It is necessary to obtain sample photo-current dependence upon light emitting diode current and to find the linear portion of this dependence. Extrapolation of this linear portion to the Y-axis gives the cut-off current. As the bias voltage is known, it is easy to calculate sample volume resistance. Then, using dark current value, one can determine the total contact resistance. The method was tested for n-type semi-insulating GaAs. The contact resistance value was shown to be approximately equal to the sample volume resistance. Thus, the influence of contacts must be taken into account when electrophysical data are analyzed.

  11. Specific and non-specific symptoms of colorectal cancer and contact to general practice

    DEFF Research Database (Denmark)

    Rasmussen, Sanne; Larsen, Pia Veldt; Søndergaard, Jens

    2015-01-01

    BACKGROUND: To improve survival rates for colorectal cancer, referral guidelines have been implemented. First step in the diagnostic process is for the individual to recognize the symptoms and contact his/her general practitioner (GP) for evaluation. OBJECTIVES: To determine (i) the prevalence...... of specific and non-specific symptom experiences indicative of colorectal cancer, (ii) the proportion of subsequent contacts to GPs, (iii) to explore the possible differences in symptom experience and contact to GPs between age and sex. METHODS: A nationwide study of 100000 adults, aged 20 years and older......, were randomly selected in the general population and invited to participate in an internet-based survey. Items regarding experience of specific and non-specific alarm symptoms of colorectal cancer within the preceding 4 weeks and contact to GP were included. RESULTS: A total of 49706 subjects completed...

  12. Low Resistance Ohmic Contacts to Bi[sub 2]Te[sub 3] Using Ni and Co Metallization

    KAUST Repository

    Gupta, Rahul P.

    2010-04-27

    A detailed study of the impact of surface preparation and postdeposition annealing on contact resistivity for sputtered Ni and Co contacts to thin-film Bi2 Te3 is presented. The specific contact resistivity is obtained using the transfer length method. It is observed that in situ sputter cleaning using Ar bombardment before metal deposition gives a surface free of oxides and other contaminants. This surface treatment reduces the contact resistivity by more than 10 times for both Ni and Co contacts. Postdeposition annealing at 100°C on samples that were sputter-cleaned further reduces the contact resistivity to < 10-7 cm2 for both Ni and Co contacts to Bi2 Te3. Co as a suitable contact metal to Bi2 Te3 is reported. Co provided similar contact resistance values as Ni, but had better adhesion and less diffusion into the thermoelectric material, making it a suitable candidate for contact metallization to Bi2 Te3 based devices. © 2010 The Electrochemical Society.

  13. Characterization of the Resistance and Force of a Carbon Nanotube/Metal Side Contact by Nanomanipulation

    OpenAIRE

    Yu, Ning; Nakajima, Masahiro; Shi, Qing; Yang, Zhan; Wang, Huaping; Sun, Lining; Huang, Qiang; Fukuda, Toshio

    2017-01-01

    A high contact resistance restricts the application of carbon nanotubes (CNTs) in fabrication of field-effect transistors (FETs). Thus, it is important to decrease the contact resistance and investigate the critical influence factors such as the contact length and contact force. This study uses nanomanipulation to characterize both the resistance and the force at a CNT/Au side-contact interface inside a scanning electron microscopy (SEM). Two-terminal CNT manipulation methods, and models for ...

  14. Role of Firing Temperature, Sheet Resistance, and Contact Area in Contact Formation on Screen-Printed Metal Contact of Silicon Solar Cell

    Science.gov (United States)

    Ahmad, Samir Mahmmod; Leong, Cheow Siu; Sopian, K.; Zaidi, Saleem H.

    2018-03-01

    Formation of an Ohmic contact requires a suitable firing temperature, appropriate doping profile, and contact dimensions within resolution limits of the screen-printing process. In this study, the role of the peak firing temperature in standard rapid thermal annealing (RTA) six-zone conveyor belt furnace (CBF) and two inexpensive alternate RTA systems [a custom-designed, three-zone, 5″-diameter quartz tube furnace (QTF) and a tabletop, 3″-diameter rapid thermal processing (RTP)] has been investigated. In addition, the role of sheet resistance and contact area in achieving low-resistance ohmic contacts has been examined. Electrical measurements of ohmic contacts between silver paste/ n +-emitter layer with varying sheet resistances and aluminum paste/ p-doped wafer were carried out in transmission line method configuration. Experimental measurements of the contact resistivity ( ρ c) exhibited the lowest values for CBF at 0.14 mΩ cm2 for Ag and 100 mΩ cm2 for Al at a peak firing temperature of 870°C. For the QTF configuration, lowest measured contact resistivities were 3.1 mΩ cm2 for Ag and 74.1 mΩ cm2 for Al at a peak firing temperature of 925°C. Finally, for the RTP configuration, lowest measured contact resistivities were 1.2 mΩ cm2 for Ag and 68.5 mΩ cm2 for Al at a peak firing temperature of 780°C. The measured contact resistivity exhibits strong linear dependence on sheet resistance. The contact resistivity for Ag decreases with contact area, while for Al the opposite behavior is observed.

  15. Study of the Contact Resistance of Interlaced Stainless Steel Yarns Embedded in Hybrid Woven Fabrics

    Directory of Open Access Journals (Sweden)

    Vasile Simona

    2017-06-01

    Full Text Available The contact resistance of two interlacing electro-conductive yarns embedded in a hybrid woven fabric will constitute a problem for electro-conductive textiles under certain circumstances. A high contact resistance can induce hotspots, while a variable contact resistance may cause malfunctioning of the components that are interconnected by the electro-conductive yarns. Moreover, the contact robustness should be preserved over time and various treatments such as washing or abrading should not alter the functioning of the electro-conductive textiles. The electrical resistance developed in the contact point of two interlacing electro-conductive yarns is the result of various factors. The influence of diameter of the electro-conductive stainless steel yarns, the weave pattern, the weft density, and the abrasion on the contact resistance was investigated. Hybrid polyester fabrics were produced according to the design of experiments (DoE and statistical models were found that describe the variation of the contact resistance with the selected input parameters. It was concluded that the diameter of the stainless steel warp and weft yarns has a statistically significant influence on the contact resistance regardless of the weave. Weft density had a significant influence on the contact resistance but only in case of the twill fabrics. Abrasion led to an increase in contact resistance regardless of the weave pattern and the type of stainless steel yarn that was used. Finally, a combination of parameters that leads to plain and twill fabrics with low contact resistance and robust contacts is recommended.

  16. Ultra-low contact resistance in graphene devices at the Dirac point

    Science.gov (United States)

    Anzi, Luca; Mansouri, Aida; Pedrinazzi, Paolo; Guerriero, Erica; Fiocco, Marco; Pesquera, Amaia; Centeno, Alba; Zurutuza, Amaia; Behnam, Ashkan; Carrion, Enrique A.; Pop, Eric; Sordan, Roman

    2018-04-01

    Contact resistance is one of the main factors limiting performance of short-channel graphene field-effect transistors (GFETs), preventing their use in low-voltage applications. Here we investigated the contact resistance between graphene grown by chemical vapor deposition (CVD) and different metals, and found that etching holes in graphene below the contacts consistently reduced the contact resistance, down to 23 Ω \\cdot μ m with Au contacts. This low contact resistance was obtained at the Dirac point of graphene, in contrast to previous studies where the lowest contact resistance was obtained at the highest carrier density in graphene (here 200 Ω \\cdot μ m was obtained under such conditions). The ‘holey’ Au contacts were implemented in GFETs which exhibited an average transconductance of 940 S m-1 at a drain bias of only 0.8 V and gate length of 500 nm, which out-perform GFETs with conventional Au contacts.

  17. Effects of pressure and temperature on thermal contact resistance between different materials

    Directory of Open Access Journals (Sweden)

    Zhao Zhe

    2015-01-01

    Full Text Available To explore whether pressure and temperature can affect thermal contact resistance, we have proposed a new experimental approach for measurement of the thermal contact resistance. Taking the thermal contact resistance between phenolic resin and carbon-carbon composites, cuprum, and aluminum as the examples, the influence of the thermal contact resistance between specimens under pressure is tested by experiment. Two groups of experiments are performed and then an analysis on influencing factors of the thermal contact resistance is presented in this paper. The experimental results reveal that the thermal contact resistance depends not only on the thermal conductivity coefficient of materials, but on the interfacial temperature and pressure. Furthermore, the thermal contact resistance between cuprum and aluminum is more sensitive to pressure and temperature than that between phenolic resin and carbon-carbon composites.

  18. Normalized Contact Force to Minimize "Electrode-Lead" Resistance in a Nanodevice

    OpenAIRE

    Lee, Seung-Hoon; Bae, Jun; Lee, Seung Woo; Jang, Jae-Won

    2014-01-01

    In this report, the contact resistance between "electrode" and "lead" is investigated for reasonable measurements of samples' resistance in a polypyrrole (PPy) nanowire device. The sample's resistance, including "electrode-lead" contact resistance, shows a decrease as force applied to the interface increases. Moreover, the sample's resistance becomes reasonably similar to, or lower than, values calculated by resistivity of PPy reported in previous studies. The decrease of electrode-lead conta...

  19. Characterization of the Resistance and Force of a Carbon Nanotube/Metal Side Contact by Nanomanipulation.

    Science.gov (United States)

    Yu, Ning; Nakajima, Masahiro; Shi, Qing; Yang, Zhan; Wang, Huaping; Sun, Lining; Huang, Qiang; Fukuda, Toshio

    2017-01-01

    A high contact resistance restricts the application of carbon nanotubes (CNTs) in fabrication of field-effect transistors (FETs). Thus, it is important to decrease the contact resistance and investigate the critical influence factors such as the contact length and contact force. This study uses nanomanipulation to characterize both the resistance and the force at a CNT/Au side-contact interface inside a scanning electron microscopy (SEM). Two-terminal CNT manipulation methods, and models for calculating the resistance and force at contact area, are proposed to guide the measurement experiments of a total resistance and a cantilever's elastic deformation. The experimental results suggest that the contact resistance of CNT/Au interface is large (189.5 kΩ) when the van der Waals force (282.1 nN) dominates the contact force at the interface. Electron-beam-induced deposition (EBID) is then carried out to decrease the contact resistance. After depositing seven EBID points, the resistance is decreased to 7.5 kΩ, and the force increases to 1339.8 nN at least. The resistance and force at the contact area where CNT was fixed exhibit a negative exponential correlation before and after EBID. The good agreement of this correlation with previous reports validates the proposed robotic system and methods for characterizing the contact resistance and force.

  20. Combined effects of fretting and pollutant particles on the contact resistance of the electrical connectors

    Directory of Open Access Journals (Sweden)

    Zhigang Kong

    2017-06-01

    Full Text Available Usually, when electrical connectors operate in vibration environments, fretting will be produced at the contact interfaces. In addition, serious environmental pollution particles will affect contact resistance of the connectors. The fretting will worsen the reliability of connectors with the pollutant particles. The combined effects of fretting and quartz particles on the contact resistance of the gold plating connectors are studied with a fretting test system. The results show that the frequencies have obvious effect on the contact resistance. The higher the frequency, the higher the contact resistance is. The quartz particles cause serious wear of gold plating, which make the nickel and copper layer exposed quickly to increase the contact resistance. Especially in high humidity environments, water supply certain adhesion function and make quartz particles easy to insert or cover the contact surfaces, and even cause opening resistance.

  1. Speci﬿c contact resistance of phase change materials to metal electrode

    NARCIS (Netherlands)

    Roy, Deepu; in 't Zandt, Micha A.A.; Wolters, Robertus A.M.

    2010-01-01

    For phase change random access memory (PCRAM) cells, it is important to know the contact resistance of phase change materials (PCMs) to metal electrodes at the contacts. In this letter, we report the systematic determination of the speci﬿c contact resistance (Ͽc ) of doped Sb2Te and Ge2Sb2Te5 to TiW

  2. Multiscale Design of Nanostructured Thermoelectric Coolers: Effects of Contact Resistances

    Science.gov (United States)

    Sharmin, Afsana; Rashid, Mohammad; Gaddipati, Vamsi; Sadeque, Abu; Ahmed, Shaikh

    2015-06-01

    Our objective is to develop a multiscale simulator for thermoelectric cooler devices, in which the material parameters are obtained atomistically using a combination of molecular dynamics and tight-binding simulations and then used in the system level design. After benchmarking the simulator against a recent experimental work, we carry out a detailed numerical investigation of the performance of Bi2Te3 nanowire-based thermoelectric devices for hot-spot cooling. The results suggest that active hotspot cooling of as much as 23°C with a high heat flux is achievable using such low-dimensionality structures. However, it has been observed that thermal and electrical contact resistances, which are quite large in nanostructures, play a critical role in determining the cooling range and lead to significant performance degradation that must be addressed before these devices can be deployed in such applications.

  3. Rolling-contact and wear resistance of hard coatings on bearing-steel substrates

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.

    1992-02-01

    Ever-increasing needs for high-performance ball- and roller-bearing components that can endure extreme applications have led to a growing interest in hard coatings for improved fatigue life and wear resistance. In particular, hard TiN and TiC coatings and, quite recently, diamond like carbon films have attracted much attention from manufacturers that produce bearing systems for both rolling- and sliding-contact applications. This paper presents an overview that highlights recent incremental progress in achieving improved fatigue and wear resistance in bearing steels through the use of hard coatings. Effects of coating adhesion, thickness, and morphology on fatigue and wear resistance of hard coatings are discussed in detail. Specific references are made to a few mechanistic models that correlate coating thickness and adhesion to improved fatigue life and wear resistance.

  4. Contact Resistance of Tantalum Coatings in Fuel Cells and Electrolyzers using Acidic Electrolytes at Elevated Temperatures

    DEFF Research Database (Denmark)

    Jensen, Annemette Hindhede; Christensen, Erik; Barner, Jens H. Von

    2014-01-01

    Tantalum has so far been found to be the only construction material with sufficient corrosion resistance for high temperature polymer electrolyte membrane electrolyzers using acidic electrolytes above 100◦C. In this work the interfacial contact resistances of tantalum plates and tantalum coated...... stainless steel were found to be far below the US Department of Energy target value of 10mcm2. The good contact resistance of tantalum was demonstrated by simulating high temperature polymer electrolyte membrane electrolysis conditions by anodization performed in 85% phosphoric acid at 130◦C, followed...... by contact resistance measurements. Upon anodization the contact resistances remained unchanged....

  5. 21 CFR 800.12 - Contact lens solutions and tablets; tamper-resistant packaging.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Contact lens solutions and tablets; tamper....12 Contact lens solutions and tablets; tamper-resistant packaging. (a) General. Unless contact lens solutions used, for example, to clean, disinfect, wet, lubricate, rinse, soak, or store contact lenses and...

  6. Patient-Specific Contact Stress Does Not Predict Polyethylene Wear Rate in a Specific Pressfit Cup.

    Science.gov (United States)

    Matziolis, Georg; Krakow, Linda; Layher, Frank; Sander, Klaus; Bossert, Joerg; Brodt, Steffen

    2017-12-01

    The most common reason for revision total hip arthroplasty remains polyethylene wear. Development dysplasia of the hip and revision situations requires a conscious compromise of implant position. The surgeon should know about the consequence on wear via a possible change in hip contact force. The objective of this study is to investigate whether annual wear is dependent on hip contact force. Forty-five inserts (DuraLoc, DePuy) that were explanted in our department were included. Three-dimensional gravimetric determination of the wear was performed by fluid displacement. Then, the hip contact force was determined using radiographs according to the Blumentritt model. No correlation was found between patient-specific factors and the annual wear. The hip contact force estimated by the Blumentritt model also showed no correlation between hip contact force and annual wear. Two single model parameters correlated significantly with wear: VRECAB as a ratio of the lever length of the spinocrural and the pelvitrochanteric muscles and the angle Alpha as a measure of the position of the center of rotation in relation to the greater trochanter. The greater the ratio spinocrural/pelvitrochanteric lever arm (R = 0.408, P = .005) and the greater the Alpha angle (more valgus the femoral neck) (R = 0.377, P = .011) were, the greater was the wear. These results lead to the conclusion that neither patient-specific factors nor the estimated hip contact force have a major influence on annual wear in the case of DuraLoc cups. Only a coxa valga and a small femoral offset contribute in a limited amount to an increase in wear. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. On the Challenges of Reducing Contact Resistances in Thermoelectric Generators Based on Half-Heusler Alloys

    DEFF Research Database (Denmark)

    Pham, Hoang Ngan; Van Nong, Ngo; Le, Thanh Hung

    2016-01-01

    -type, respectively. Using this method, the quality of the HH–electrode contacts is improved due to their low electrical contact resistance and less reaction– diffusion layer. The microstructure and chemical composition of the joints were examined using a scanning electron microscope equipped with energydispersive x......-ray analysis. The electrical characteristics of the interfaces at the contacts were studied based on electrical contact resistance and Seebeck scanning microprobe measurements. In this paper, we show that joining the HH to a Ag electrode directly using fast hot pressing resulted in lower contact resistance...

  8. Method for making low-resistivity contacts to high T/sub c/ superconductors

    International Nuclear Information System (INIS)

    Ekin, J.W.; Panson, A.J.; Blankenship, B.A.

    1988-01-01

    A method for making low-resistivity contacts to high T/sub c/ superconductors has been developed, which has achieved contact surface resistivities less than 10 μΩ cm 2 at 76 K and does not require sample heating above ∼150 0 C. This is an upper limit for the contact resistivity obtained at high current densities up to 10 2 --10 3 A/cm 2 across the contact interface. At lower measuring current densities the contact resistivities were lower and the voltage-current curve was nonlinear, having a superconducting transition character. On cooling from 295 to 76 K, the contact resistivity decreased several times, in contrast to indium solder contacts where the resistivity increased on cooling. The contacts showed consistently low resistivity and little degradation when exposed to dry air over a four-month period and when repeatedly cycled between room temperature and 76 K. The contacts are formed by sputter depositing a layer of a noble metal-silver and gold were used-on a clean superconductor surface to protect the surface and serve as a contact pad. External connections to the contact pads have been made using both solder and wire-bonding techniques

  9. Experimental consideration of contact resistance related to modified configuration of line contact; Sen sessyokusi no sessyoku keitai ni tomonau sessyoku teiko no jikkenteki kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Aichi, H. [Daido Institute of Technology, Aichi (Japan); Miyachi, I. [Aichi Institute of Technology, Aichi (Japan)

    1997-06-20

    The contact form of electric contact which is used on a switchgear is roughly divided to a point, a line and a plane contact. Among them, a point contact is considered as the foundation of contact form and according to the contact structures such as spherical surface vs. spherical surface and spherical surface vs. plane and so on, one of the minute circular contacts, so called a point contact, is formed. On the most of the connectors and the circuit-breakers, the line or the plane contact member is applied. Authors have been developed an unique contact model be able to measure the contact resistance of any form. In this model, it is available to select the size, the member and the configuration of contact spots by macroscopic arrangement of some metal electrodes immersed in electrolyte solution of dilute sulfuric acid. In this paper, the contact resistance of a case that changes from line to plane contact and that of several line contacts in parallel are studied. The experimental results obtained clarify that the characteristics of contact resistance changed form line to plane contact are equivalent to those of a point contact, the contact resistance of line contacts in parallel has the same characteristics as that of a long line contact and so forth. 9 refs., 8 figs.

  10. Livestock-associated methicillin and multidrug resistant S. aureus in humans is associated with occupational pig contact, not pet contact.

    Science.gov (United States)

    Ye, Xiaohua; Fan, Yanping; Wang, Xiaolin; Liu, Weidong; Yu, Haifeng; Zhou, Junli; Chen, Sidong; Yao, Zhenjiang

    2016-01-12

    This study aimed to explore the association of livestock-associated S. aureus with occupational pig contact and pet contact. In this cross-sectional study, 1,422 participants (including 244 pig workers, 200 pet-owning workers and 978 control workers) responded to a questionnaire and provided a nasal swab for S. aureus analysis. Resulting isolates were tested for antibiotic susceptibility, the immune evasion cluster (IEC) genes, and multilocus sequence type. Compared with controls, the pig workers demonstrated a greater prevalence of multidrug-resistant S. aureus (MDRSA) [prevalence ratio (PR) = 3.38; 95% CI: 2.07-5.53] and methicillin-resistant S. aureus (MRSA) (PR = 7.42; 95% CI: 3.71-14.83), but the prevalence of MDRSA and MRSA was similar in pet-owning workers and controls. There was a positive relation of frequency of pig contact with prevalence of MDRSA and MRSA carriage. Only pig workers carried MDRSA CC9 (16 isolates) and MRSA CC9 (16 isolates), and all of these isolates were tetracycline resistant and absent of IEC genes. These findings suggest that livestock-associated MRSA and MDRSA(CC9, IEC-negative, tetracycline-resistant) in humans is associated with occupational pig contact, not pet contact, and support growing concern about antibiotics use in pig farms and raising questions about the potential for occupational exposure to opportunistic S. aureus.

  11. A method for direct contact resistance evaluation in low voltage coplanar organic field-effect transistors

    Science.gov (United States)

    Lai, S.; Cosseddu, P.; Bonfiglio, A.

    2017-04-01

    In this paper, a method for the extrapolation of contact resistance in organic field-effect transistors (OFETs) from a single transfer characteristic curve in the linear regime is proposed. The method, namely DIrect Contact Resistance Extrapolation (DICRE), is based on the idea of making the current dependent only on contact resistance by setting the device in large over-threshold conditions. Constant contact resistance with respect to gate-to-source voltage is considered as an acceptable approximation, as confirmed by other examples in the literature. The effectiveness of the method is demonstrated by extrapolating the contact resistance of two different OFET structures (self-aligned and not self-aligned) and comparing the results with standard reference techniques, namely the Modified Transmission Line Method (M-TLM) and the Y function method. The results demonstrate that the DICRE method can be applied to low voltage devices without any damage to the gate insulator, even if the applied gate-to-source voltage drop is well beyond the values normally employed for transistor operation. The proposed method allows extrapolating a value of contact resistance comparable with the ones derived by TLM, with restrained variability. Moreover, the capability of properly recognizing the differences in contact resistance values between OFET structures with different features in terms of source/drain-gate overlap is reported. Finally, the possibility of correctly deriving the contact resistance dependence on drain-to-source voltage using DICRE is discussed.

  12. Contact resistance problems applying ERT on low bulk density forested stony soils. Is there a solution?

    Science.gov (United States)

    Deraedt, Deborah; Touzé, Camille; Robert, Tanguy; Colinet, Gilles; Degré, Aurore; Garré, Sarah

    2015-04-01

    contact resistance reduced to 5222 Ω. This improved the contact resistance substantially, but complicates the execution of a pulse tracer experiment. To date we did not find any better solution to this problem and we keep searching a way to improve the contact resistance in stony forested soils with very low bulk density. We would like to exchange on these questions with EGU attendees in order to improve the experimental design or point out a new research path for these specific conditions. This could lead to enhance the use of ERT in soils with low density and high stone content.

  13. The Universal Influence of Contact Resistance on the Efficiency of a Thermoelectric Generator

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2015-01-01

    . For all systems, a universal influence of both the electrical and thermal contact resistance is observed on the leg’s efficiency, when the systems are analyzed in terms of the contribution of the contact resistance to the total resistance of the leg. The results are compared with the analytical model......The influence of electrical and thermal contact resistance on the efficiency of a segmented thermoelectric generator is investigated. We consider 12 different segmented p-legs and 12 different segmented n-legs, using eight different p-type and eight different n-type thermoelectric materials...

  14. Finite element analysis on the influence of contact resistivity in an extraordinary magnetoresistance magnetic field micro sensor

    KAUST Repository

    Sun, Jian

    2011-08-06

    In this paper, an extraordinary magnetoresistance (EMR) device made of an InSb/Au hybrid structure was investigated. Those devices have a large potential in becoming a new generation of highly sensitive and cheap magnetic micro sensors. A crucial factor for the performance is the interface between the InSb and Au, which suffers from a certain contact resistivity. The Finite Element Method (FEM) was employed to simulate the current redistribution in the device, under an applied magnetic field. Specifically, the influence of the contact resistivity between the InSb bulk and Au shunt was studied. In a device with optimized geometry and without contact resistivity between the layers of InSb and Au, the EMR effect and the sensitivity show values of 1.89 × 104% and 0.02%/(10-4 T), respectively, at 1 Tesla. For values of contact resistivity up to 10-8cm2 the EMR effect is almost constant, while for higher values the EMR effect decreases exponentially. However, the sensitivity of the device does not decrease until 5 × 10-6 cm2 of contact resistivity. Only beyond this value the sensitivity, which in most cases is associated with the performance of the device, will deteriorate. © Springer Science+Business Media, LLC 2011.

  15. A Low Resistance Calcium/Reduced Titania Passivated Contact for High Efficiency Crystalline Silicon Solar Cells

    KAUST Repository

    Allen, Thomas G.

    2017-02-04

    Recent advances in the efficiency of crystalline silicon (c-Si) solar cells have come through the implementation of passivated contacts that simultaneously reduce recombination and resistive losses within the contact structure. In this contribution, low resistivity passivated contacts are demonstrated based on reduced titania (TiOx) contacted with the low work function metal, calcium (Ca). By using Ca as the overlying metal in the contact structure we are able to achieve a reduction in the contact resistivity of TiOx passivated contacts of up to two orders of magnitude compared to previously reported data on Al/TiOx contacts, allowing for the application of the Ca/TiOx contact to n-type c-Si solar cells with partial rear contacts. Implementing this contact structure on the cell level results in a power conversion efficiency of 21.8% where the Ca/TiOx contact comprises only ≈6% of the rear surface of the solar cell, an increase of 1.5% absolute compared to a similar device fabricated without the TiOx interlayer.

  16. Laser cladding of copper with molybdenum for wear resistance enhancement in electrical contacts

    International Nuclear Information System (INIS)

    Ng, K.W.; Man, H.C.; Cheng, F.T.; Yue, T.M.

    2007-01-01

    Laser cladding of Mo on Cu has been attempted with the aim of enhancing the wear resistance and hence increasing the service life of electrical contacts made of Cu. In order to overcome the difficulties arising from the large difference in thermal properties and the low mutual solubility between Cu and Mo, Ni was introduced as an intermediate layer between Mo and Cu. The Ni and Mo layers were laser clad one after the other to form a sandwich layer of Mo/Ni/Cu. Excellent bonding between the clad layer and the Cu substrate was ensured by strong metallurgical bonding. The hardness of the surface of the clad layer is seven times higher than that of the Cu substrate. Pin-on-disc wear tests consistently showed that the abrasive wear resistance of the clad layer was also improved by a factor of seven as compared with untreated Cu substrate. The specific electrical contact resistance of the clad surface was about 5.6 x 10 -7 Ω cm 2

  17. Reducing contact resistance in ferroelectric organic transistors by buffering the semiconductor/dielectric interface

    Science.gov (United States)

    Sun, Huabin; Yin, Yao; Wang, Qijing; Jun, Qian; Wang, Yu; Tsukagoshi, Kazuhito; Wang, Xizhang; Hu, Zheng; Pan, Lijia; Zheng, Youdou; Shi, Yi; Li, Yun

    2015-08-01

    The reduction of contact resistance in ferroelectric organic field-effect transistors (Fe-OFETs) by buffering the interfacial polarization fluctuation was reported. An ultrathin poly(methyl methacrylate) layer was inserted between the ferroelectric polymer and organic semiconductor layers. The contact resistance was significantly reduced to 55 kΩ cm. By contrast, Fe-OFETs without buffering exhibited a significantly larger contact resistance of 260 kΩ cm. Results showed that such an enhanced charge injection was attributed to the buffering effect at the semiconductor/ferroelectric interface, which narrowed the trap distribution of the organic semiconductor in the contact region. The presented work provided an efficient method of lowering the contact resistance in Fe-OFETs, which is beneficial for the further development of Fe-OFETs.

  18. A contact resistance model for scanning probe phase-change memory

    International Nuclear Information System (INIS)

    Wang, Lei; Ying, Jin; Wei Yang, Guo; Wright, David; Aziz, Mustafa

    2014-01-01

    A novel mechanical model was proposed to calculate the contact resistance at tip and capping layer interface for scanning probe phase-change memory applications. The resulting I–V curve calculated from this model that combines Hertzian contact theory with the Schottky diode effect has exhibited a good agreement with the experimental measurements under the same system architecture. The role of contact resistance on the write efficacy of scanning probe phase-change memory was also evaluated by introducing the calculated contact resistance into the previous electrothermal simulations for cases of writing crystalline bits in amorphous starting phase and writing amorphous bits in crystalline starting phase. The consequent written marks and I–V curve show a closer match with the experimental observation compared to the case without including contact resistance. (technical note)

  19. Investigation into Contact Resistance And Damage of Metal Contacts Used in RF-MEMS Switches

    Science.gov (United States)

    2009-09-01

    during this study. XPS analysis accomplished at Lehigh University determined that the contaminant on the test cantilever appeared to be a hydrocar- bon ...fabricate sil- icon cantilevers with a contact bump. The preparation and etch of contact bumps onto custom SOIMUMPS die consisted of the following...Run. Icon is on desktop. 20. Select COM3 as the port and 9600 baud to connect to C-865. 21. Select Connect Stage -- connect to M663.465. Note: Do NOT

  20. Numerical simulation of high-temperature thermal contact resistance and its reduction mechanism

    Science.gov (United States)

    Zhang, Jing

    2018-01-01

    High-temperature thermal contact resistance (TCR) plays an important role in heat-pipe-cooled thermal protection structures due to the existence of contact interface between the embedded heat pipe and the heat resistive structure, and the reduction mechanism of thermal contact resistance is of special interests in the design of such structures. The present paper proposed a finite element model of the high-temperature thermal contact resistance based on the multi-point contact model with the consideration of temperature-dependent material properties, heat radiation through the cavities at the interface and the effect of thermal interface material (TIM), and the geometry parameters of the finite element model are determined by simple surface roughness test and experimental data fitting. The experimental results of high-temperature thermal contact resistance between superalloy GH600 and C/C composite material are employed to validate the present finite element model. The effect of the crucial parameters on the thermal contact resistance with and without TIM are also investigated with the proposed finite element model. PMID:29547651

  1. Experimental consideration on the contact resistance caused by the distribution of contact spots with the contact model using electrolyte bath; Denkai yokuso wo mochiita sesshoku model ni yoru sesshokuten no bunpu to sesshoku teiko tokusei ni kansuru jikkenteki kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Aichi, H. [Daido Institute of Technology, Aichi (Japan); Miyachi, I. [Aichi Institute of Technology, Aichi (Japan)

    1996-09-20

    Electric contact members are classified by the form such as a point, a line, and a plane. Particularly, the point contact member which makes a small circular contact spot is basis of the contact form. Also, the plane contact member will make many contact spots which are different in size and distributing over the contacting portion. Authors have been developing the contact model to measure the contact resistance. In this model, it is available to select the size, the number, and the arrangement of contact spots by the macroscopical contact spots which are formed with some metal electrodes arranged in electrolyte solution of dilute sulfuric acid. In this paper, the fundamental characteristics of the contact resistance caused by the construction of current are investigated with 1 to 3 contact spot models. Then the relations between the contact resistance and the distribution of the contact spots are examined with 2 to 9 multi-contact spot models. As the results, it is cleared that the proposed contact model presents the successful experimental method for the analysis of the contact resistance. 9 refs., 8 tabs.

  2. Characterization of micro-contact resistance between a gold nanocrystalline line and a tungsten electrode probe in interconnect fatigue testing.

    Science.gov (United States)

    Ling, Xue; Wang, Yusheng; Li, Xide

    2014-10-01

    An electromechanically-coupled micro-contact resistance measurement system is built to mimic the contact process during fatigue testing of nanoscale-thickness interconnects using multiple probe methods. The design combines an optical microscope, high-resolution electronic balance, and micromanipulator-controlled electric probe, and is coupled with electrical measurements to investigate microscale contact physics. Experimental measurements are performed to characterize the contact resistance response of the gold nanocrystalline pad of a 35-nm-thick interconnect under mechanical force applied by a tungsten electrode probe. Location of a stable region for the contact resistance and the critical contact force provides better understanding of micro-contact behavior relative to the effects of the contact force and the nature of the contact surface. Increasing contact temperature leads to reduced contact resistance, softens the pad material, and modifies the contact surface. The stability of both contact resistance and interconnect resistance is studied under increasing contact force. Major fluctuations emerge when the contact force is less than the critical contact force, which shows that temporal contact resistance will affect interconnect resistance measurement accuracy, even when using the four-wire method. This performance is demonstrated experimentally by heating the Au line locally with a laser beam. Finally, the contact resistances are calculated using the LET (Li-Etsion-Talke) model together with combined Holm and Sharvin theory under various contact forces. Good agreement between the results is obtained. This research provides a way to measure change in interconnect line resistance directly under a stable contact resistance regime with a two-wire method that will greatly reduce the experimental costs.

  3. Simultaneous atomic force microscopy measurement of topography and contact resistance of metal films and carbon nanotubes

    International Nuclear Information System (INIS)

    Stadermann, M.; Grube, H.; Boland, J.J.; Papadakis, S.J.; Falvo, M.R.; Superfine, R.; Washburn, S.

    2003-01-01

    We present a quartz tuning-fork-based atomic force microscopy (AFM) setup that is capable of mapping the surface contact resistance while scanning topography. The tuning-fork setup allows us to use etched Pt/Ir tips, which have higher durability and better conductivity than probes used in earlier AFM conductance measurements. The performance of the method is demonstrated with contact resistance measurements of gold lines on silicon dioxide and carbon nanotubes on graphite

  4. Negative-resistance voltage-current characteristics of superconductor contact junctions for macro-scale applications

    CERN Document Server

    Takayasu, M; Minervini, J V; 10.1109/TASC.2003.812854

    2003-01-01

    Voltage-current characteristics of mechanical pressure contact junctions between superconducting wires are investigated using a voltage-driving method. It is found that the switching regions at low voltages result from negative resistance of the contact junction. The current transport of the contact junctions is discussed from the perspective of two existing models: the multiple Andreev reflections at the two SN interfaces of a SNS (Superconductor/Normal metal /Superconductor) junction and the inhomogeneous multiple Josephson weak-link array. (13 refs).

  5. Contact resistance of TiW to ultra-thin phase change material layers

    NARCIS (Netherlands)

    Roy, Deepu; Klootwijk, J.H.; Gravesteijn, Dirk J; Wolters, Robertus A.M.

    2011-01-01

    In this article we report on the change in contact resistance of TiW to doped-Sb2Te in the 5nm-50nm thickness range of the PCM layer. This interface is characterized both in the amorphous and in crystalline state of doped-Sb2Te. The nature of the interface is characterized by electrical contact

  6. Knee medial and lateral contact forces in a musculoskeletal model with subject-specific contact point trajectories.

    Science.gov (United States)

    Zeighami, A; Aissaoui, R; Dumas, R

    2018-03-01

    Contact point (CP) trajectory is a crucial parameter in estimating medial/lateral tibio-femoral contact forces from the musculoskeletal (MSK) models. The objective of the present study was to develop a method to incorporate the subject-specific CP trajectories into the MSK model. Ten healthy subjects performed 45 s treadmill gait trials. The subject-specific CP trajectories were constructed on the tibia and femur as a function of extension-flexion using low-dose bi-plane X-ray images during a quasi-static squat. At each extension-flexion position, the tibia and femur CPs were superimposed in the three directions on the medial side, and in the anterior-posterior and proximal-distal directions on the lateral side to form the five kinematic constraints of the knee joint. The Lagrange multipliers associated to these constraints directly yielded the medial/lateral contact forces. The results from the personalized CP trajectory model were compared against the linear CP trajectory and sphere-on-plane CP trajectory models which were adapted from the commonly used MSK models. Changing the CP trajectory had a remarkable impact on the knee kinematics and changed the medial and lateral contact forces by 1.03 BW and 0.65 BW respectively, in certain subjects. The direction and magnitude of the medial/lateral contact force were highly variable among the subjects and the medial-lateral shift of the CPs alone could not determine the increase/decrease pattern of the contact forces. The suggested kinematic constraints are adaptable to the CP trajectories derived from a variety of joint models and those experimentally measured from the 3D imaging techniques. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Fatigue resistant carbon coatings for rolling/sliding contacts

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harpal; Ramirez, Giovanni; Eryilmaz, Osman; Greco, Aaron; Doll, Gary; Erdemir, Ali

    2016-06-01

    The growing demands for renewable energy production have recently resulted in a significant increase in wind plant installation. Field data from these plants show that wind turbines suffer from costly repair, maintenance and high failure rates. Often times the reliability issues are linked with tribological components used in wind turbine drivetrains. The primary failure modes in bearings and gears are associated with micropitting, wear, brinelling, scuffing, smearing and macropitting all of which occur at or near the surface. Accordingly, a variety of surface engineering approaches are currently being considered to alter the near surface properties of such bearings and gears to prevent these tribological failures. In the present work, we have evaluated the tribological performance of compliant highly hydrogenated diamond like carbon coating developed at Argonne National Laboratory, under mixed rolling/sliding contact conditions for wind turbine drivetrain components. The coating was deposited on AISI 52100 steel specimens using a magnetron sputter deposition system. The experiments were performed on a PCS Micro-Pitting-Rig (MPR) with four material pairs at 1.79 GPa contact stress, 40% slide to roll ratio and in polyalphaolefin (PAO4) basestock oil (to ensure extreme boundary conditions). The post-test analysis was performed using optical microscopy, surface profilometry, and Raman spectroscopy. The results obtained show a potential for these coatings in sliding/rolling contact applications as no failures were observed with coated specimens even after 100 million cycles compared to uncoated pair in which they failed after 32 million cycles, under the given test conditions.

  8. Determination of a Wear Initiation Cycle by using a Contact Resistance Measurement in Nuclear Fuel Fretting

    International Nuclear Information System (INIS)

    Lee, Young Ho; Kim, Hyung Kyu

    2008-01-01

    In nuclear fuel fretting, the improving of the contact condition with a modified spring shape is a useful method for increasing the wear resistance of the nuclear fuel rod. This is because the fretting wear resistance between the fuel rod and grid spring is mainly affected by the grid spring shape rather than the environment, the contact modes, etc. In addition, the wear resistance is affected by the wear debris behavior between contact surfaces. So, it is expected that the wear initiation of each spring shape should be determined in order to evaluate a wear resistance. However, it is almost impossible to measure the wear behavior in contact surfaces on a real time basis because the contact surfaces are always hidden. Besides, the results of the worn surface observation after the fretting wear tests are restricted to archive the information on the wear debris behavior and the formation mechanism of the wear scar. In order to evaluate the wear behavior during the fretting wear tests, it is proposed that the contact resistance measurement is a useful method for examining the wear initiation cycle and modes. Generally, fretting wear damages are rapidly progressed by a localized plastic deformation between the contact surfaces, crack initiation and fracture of the deformed surface with a strain hardening difference between a surface and a subsurface and finally a detachment of wear debris. After this, wear debris is easily oxidized by frictional heat, test environment, etc. At this time, a small amount of electric current applied between the contact surfaces will be influenced by the wear debris, which could be an obstacle to an electric current flow. So, it is possible to archive the information on the wear behavior by measuring the contact resistance. In order to determine the wear initiation cycle during the fretting wear tests, in this study, fretting wear tests have been performed by applying a constant electric current in room temperature air

  9. Reconsidering contact precautions for endemic methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus.

    Science.gov (United States)

    Morgan, Daniel J; Murthy, Rekha; Munoz-Price, L Silvia; Barnden, Marsha; Camins, Bernard C; Johnston, B Lynn; Rubin, Zachary; Sullivan, Kaede V; Shane, Andi L; Dellinger, E Patchen; Rupp, Mark E; Bearman, Gonzalo

    2015-10-01

    Whether contact precautions (CP) are required to control the endemic transmission of methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) in acute care hospitals is controversial in light of improvements in hand hygiene, MRSA decolonization, environmental cleaning and disinfection, fomite elimination, and chlorhexidine bathing. To provide a framework for decision making around use of CP for endemic MRSA and VRE based on a summary of evidence related to use of CP, including impact on patients and patient care processes, and current practices in use of CP for MRSA and VRE in US hospitals. A literature review, a survey of Society for Healthcare Epidemiology of America Research Network members on use of CP, and a detailed examination of the experience of a convenience sample of hospitals not using CP for MRSA or VRE. Hospital epidemiologists and infection prevention experts. No high quality data support or reject use of CP for endemic MRSA or VRE. Our survey found more than 90% of responding hospitals currently use CP for MRSA and VRE, but approximately 60% are interested in using CP in a different manner. More than 30 US hospitals do not use CP for control of endemic MRSA or VRE. Higher quality research on the benefits and harms of CP in the control of endemic MRSA and VRE is needed. Until more definitive data are available, the use of CP for endemic MRSA or VRE in acute care hospitals should be guided by local needs and resources.

  10. Low resistivity contact to iron-pnictide superconductors

    Science.gov (United States)

    Tanatar, Makariy; Prozorov, Ruslan; Ni, Ni; Bud& #x27; ko, Sergey; Canfield, Paul

    2013-05-28

    Method of making a low resistivity electrical connection between an electrical conductor and an iron pnictide superconductor involves connecting the electrical conductor and superconductor using a tin or tin-based material therebetween, such as using a tin or tin-based solder. The superconductor can be based on doped AFe.sub.2As.sub.2, where A can be Ca, Sr, Ba, Eu or combinations thereof for purposes of illustration only.

  11. Hypersensitivity to contact inhibition provides a clue to cancer resistance of naked mole-rat.

    Science.gov (United States)

    Seluanov, Andrei; Hine, Christopher; Azpurua, Jorge; Feigenson, Marina; Bozzella, Michael; Mao, Zhiyong; Catania, Kenneth C; Gorbunova, Vera

    2009-11-17

    The naked mole-rat is the longest living rodent with a maximum lifespan exceeding 28 years. In addition to its longevity, naked mole-rats have an extraordinary resistance to cancer as tumors have never been observed in these rodents. Furthermore, we show that a combination of activated Ras and SV40 LT fails to induce robust anchorage-independent growth in naked mole-rat cells, while it readily transforms mouse fibroblasts. The mechanisms responsible for the cancer resistance of naked mole-rats were unknown. Here we show that naked mole-rat fibroblasts display hypersensitivity to contact inhibition, a phenomenon we termed "early contact inhibition." Contact inhibition is a key anticancer mechanism that arrests cell division when cells reach a high density. In cell culture, naked mole-rat fibroblasts arrest at a much lower density than those from a mouse. We demonstrate that early contact inhibition requires the activity of p53 and pRb tumor suppressor pathways. Inactivation of both p53 and pRb attenuates early contact inhibition. Contact inhibition in human and mouse is triggered by the induction of p27(Kip1). In contrast, early contact inhibition in naked mole-rat is associated with the induction of p16(Ink4a). Furthermore, we show that the roles of p16(Ink4a) and p27(Kip1) in the control of contact inhibition became temporally separated in this species: the early contact inhibition is controlled by p16(Ink4a), and regular contact inhibition is controlled by p27(Kip1). We propose that the additional layer of protection conferred by two-tiered contact inhibition contributes to the remarkable tumor resistance of the naked mole-rat.

  12. The effect of metallization contact resistance on the measurement of the field effect mobility of long-channel unannealed amorphous In–Zn–O thin film transistors

    International Nuclear Information System (INIS)

    Lee, Sunghwan; Park, Hongsik; Paine, David C.

    2012-01-01

    The effect of contact resistance on the measurement of the field effect mobility of compositionally homogeneous channel indium zinc oxide (IZO)/IZO metallization thin film transistors (TFTs) is reported. The TFTs studied in this work operate in depletion mode as n-channel field effect devices with a field effect mobility calculated in the linear regime (μ FE ) of 20 ± 1.9 cm 2 /Vs and similar of 18 ± 1.3 cm 2 /Vs when calculated in the saturation regime (μ FE sat ). These values, however, significantly underestimate the channel mobility since a large part of the applied drain voltage is dropped across the source/drain contact interface. The transmission line method was employed to characterize the contact resistance and it was found that the conducting-IZO/semiconducting-IZO channel contact is highly resistive (specific contact resistance, ρ C > 100 Ωcm 2 ) and, further, this contact resistance is modulated with applied gate voltage. Accounting for the contact resistance (which is large and modulated by gate voltage), the corrected μ FE is shown to be 39 ± 2.6 cm 2 /Vs which is consistent with Hall mobility measurements of high carrier density IZO.

  13. Evaluation of contact precautions for methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus.

    Science.gov (United States)

    Bardossy, Ana Cecilia; Alsafadi, Muhammad Yasser; Starr, Patricia; Chami, Eman; Pietsch, Jennifer; Moreno, Daniela; Johnson, Laura; Alangaden, George; Zervos, Marcus; Reyes, Katherine

    2017-12-01

    There are limited controlled data demonstrating contact precautions (CPs) prevent methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) infections in endemic settings. We evaluated changes in hospital-acquired MRSA and VRE infections after discontinuing CPs for these organisms. This is a retrospective study done at an 800-bed teaching hospital in urban Detroit. CPs for MRSA and VRE were discontinued hospital-wide in 2013. Data on MRSA and VRE catheter-associated urinary tract infections (CAUTIs), ventilator-associated pneumonia (VAP), central line-associated bloodstream infections (CLABSIs), surgical site infections (SSIs), and hospital-acquired MRSA bacteremia (HA-MRSAB) rates were compared before and after CPs discontinuation. There were 36,907 and 40,439 patients hospitalized during the two 12-month periods: CPs and no CPs. Infection rates in the CPs and no-CPs periods were as follows: (1) MRSA infections: VAP, 0.13 versus 0.11 (P = .84); CLABSI, 0.11 versus 0.19 (P = .45); SSI, 0 versus 0.14 (P = .50); and CAUTI, 0.025 versus 0.033 (P = .84); (2) VRE infections: CAUTI, 0.27 versus 0.13 (P = .19) and CLABSI, 0.29 versus 0.3 (P = .94); and (3) HA-MRSAB rates: 0.14 versus 0.11 (P = .55), respectively. Discontinuation of CPs did not adversely impact endemic MRSA and VRE infection rates. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  14. Origin of the abnormal behavior of contact resistance in Ohmic contacts to laser-irradiated n-type GaN

    International Nuclear Information System (INIS)

    Jang, Ho Won; Lee, Jong-Lam

    2009-01-01

    Abnormal behavior of contact resistance with annealing in Ohmic contacts to laser-irradiated n-GaN is investigated. Ti/Al contacts on as-grown n-GaN shows no change in contact resistivity with annealing at the temperature range of 100-400 deg. C. However, the annealing results in the significant increase in contact resistivity in the contacts on laser-irradiated n-GaN. Synchrotron radiation photoemission study reveals the reduction of the concentration of donor-like N vacancies near the surface by the annealing. These results suggest that preventing the annihilation of N vacancies in the laser-irradiated n-GaN is important in improving the performance of vertical-structure GaN-based light-emitting diodes fabricated by laser lift-off.

  15. Effect of air confinement on thermal contact resistance in nanoscale heat transfer

    Science.gov (United States)

    Pratap, Dheeraj; Islam, Rakibul; Al-Alam, Patricia; Randrianalisoa, Jaona; Trannoy, Nathalie

    2018-03-01

    Here, we report a detailed analysis of thermal contact resistance (R c) of nano-size contact formed between a Wollaston wire thermal probe and the used samples (fused silica and titanium) as a function of air pressure (from 1 Pa to 105 Pa). Moreover, we suggest an analytical model using experimental data to extract R c. We found that for both samples, the thermal contact resistance decreases with increasing air pressure. We also showed that R c strongly depends on the thermal conductivity of materials keeping other parameters the same, such as roughness of the probe and samples, as well as the contact force. We provide a physical explanation of the R c trend with pressure and thermal conductivity of the materials: R c is ascribed to the heat transfer through solid-solid (probe-sample) contact and confined air at nanoscale cavities, due to the rough nature of the materials in contact. The contribution of confined air on heat transfer through the probe sample contact is significant at atmospheric pressure but decreases as the pressure decreases. In vacuum, only the solid-solid contact contributes to R c. In addition, theoretical calculations using the well-known acoustic and diffuse mismatch models showed a high thermal conductivity material that exhibits high heat transmission and consequently low R c, supporting our findings.

  16. Subject-specific knee joint geometry improves predictions of medial tibiofemoral contact forces

    Science.gov (United States)

    Gerus, Pauline; Sartori, Massimo; Besier, Thor F.; Fregly, Benjamin J.; Delp, Scott L.; Banks, Scott A.; Pandy, Marcus G.; D’Lima, Darryl D.; Lloyd, David G.

    2013-01-01

    Estimating tibiofemoral joint contact forces is important for understanding the initiation and progression of knee osteoarthritis. However, tibiofemoral contact force predictions are influenced by many factors including muscle forces and anatomical representations of the knee joint. This study aimed to investigate the influence of subject-specific geometry and knee joint kinematics on the prediction of tibiofemoral contact forces using a calibrated EMG-driven neuromusculoskeletal model of the knee. One participant fitted with an instrumented total knee replacement walked at a self-selected speed while medial and lateral tibiofemoral contact forces, ground reaction forces, whole-body kinematics, and lower-limb muscle activity were simultaneously measured. The combination of generic and subject-specific knee joint geometry and kinematics resulted in four different OpenSim models used to estimate muscle-tendon lengths and moment arms. The subject-specific geometric model was created from CT scans and the subject-specific knee joint kinematics representing the translation of the tibia relative to the femur was obtained from fluoroscopy. The EMG-driven model was calibrated using one walking trial, but with three different cost functions that tracked the knee flexion/extension moments with and without constraint over the estimated joint contact forces. The calibrated models then predicted the medial and lateral tibiofemoral contact forces for five other different walking trials. The use of subject-specific models with minimization of the peak tibiofemoral contact forces improved the accuracy of medial contact forces by 47% and lateral contact forces by 7%, respectively compared with the use of generic musculoskeletal model. PMID:24074941

  17. Semianalytical model of the contact resistance in two-dimensional semiconductors

    Science.gov (United States)

    Grassi, Roberto; Wu, Yanqing; Koester, Steven J.; Low, Tony

    2017-10-01

    Contact resistance is a severe performance bottleneck for electronic devices based on two-dimensional (2D) layered semiconductors, whose contacts are Schottky rather than Ohmic. Although there is a general consensus that the injection mechanism changes from thermionic to tunneling with gate biasing, existing models tend to oversimplify the transport problem, by neglecting the 2D transport nature and the modulation of the Schottky barrier height, the latter being of particular importance in back-gated devices. In this paper, we develop a semianalytical model based on Bardeen's transfer Hamiltonian approach to describe both effects. Remarkably, our model is able to reproduce several experimental observations of a metallic behavior in the contact resistance, i.e., a decreasing resistance with decreasing temperature, occurring at high gate voltages.

  18. An analytical solution for contact resistance of staggered organic field-effect transistors

    Science.gov (United States)

    Karimi-Alavijeh, Hamidreza; Katebi-Jahromi, Alireza

    2017-03-01

    We have developed analytical models for bias dependent contact resistance (RC) and output characteristics of staggered organic field-effect transistors (OFETS) based on a bulk resistance-approximated and mobility-modified current-crowding method. Numerical evaluations of RC and its resistive components show that the bias dependency of the bulk resistance is negligible. Consequently, the properties of the active layer interfaces determine RC and its characteristics. Effective parameters include a normally constant charge injection barrier at the organic-metal interface (Eb) and a gate induced surface carrier-concentration (PS0) at the organic-insulator boundary. The energy barrier pertains to the fabrication process, and its related resistance (rc) can be determined as the fitting parameter of the theoretical model. However, PS0 is strongly gate bias dependent and the results of the numerical model indicate that the resulting component (rch) is dominant and has a considerable effect on RC and its characteristics. More importantly, PS0 as the key parameter of the contact resistance is analytically expressible and by using a proposed mobility-modified current-crowding model, the contact resistance can be analytically formulated. Accordingly, the output characteristics of the OFETs in the triode region can be also analytically modeled using the developed relation of RC.

  19. Low interfacial contact resistance of Al-graphene composites via interface engineering

    Science.gov (United States)

    Hahm, Myung Gwan; Nam, Jaewook; Choi, Minseok; Park, Chi-Dong; Cho, Byungjin; Kazunori, Sanada; Ahm Kim, Yoong; Kim, Dong Young; Endo, Morinobu; Kim, Dong-Ho; Vajtai, Robert; Ajayan, Pulickel M.; Moo Song, Sung

    2015-05-01

    Al-based composites incorporating multilayered graphene sheets were developed via a facile approach. The multilayered graphene sheets were fabricated from the expanded graphite via a simple mechanical exfoliation process. The facile extrusion molding process with Al powder and graphene sheets exfoliated from expended graphite afforded Al-based graphene composite rods. These composites showed enhanced thermal conductivity compared to the pristine Al rods. Moreover, the Al-based multilayered graphene sheet composites exhibited lower interfacial contact resistance between graphene-based electrodes than the pristine Al. With increasing degrees of dispersion, the number of exposed graphene sheets increases, thereby significantly decreasing the interfacial contact resistance between the composite and external graphite electrode.

  20. Method for forming low-resistance ohmic contacts on semiconducting oxides

    Science.gov (United States)

    Narayan, J.

    1979-10-01

    The invention provides a new method for the formation of high-quality ohmic contacts on wide-band-gap semiconducting oxides. As exemplified by the formation of an ohmic contact on n-type BaTiO/sub 3/ containing a p-n junction, the invention entails depositing a film of a metallic electroding material on the BaTiO/sub 3/ surface and irradiating the film with a Q-switched laser pulse effecting complete melting of the film and localized melting of the surface layer of oxide immediately underlying the film. The resulting solidified metallic contact is ohmic, has unusually low contact resistance, and is thermally stable, even at elevated temmperatures. The contact does not require cleaning before attachment of any suitable electrical lead. This method is safe, rapid, reproducible, and relatively inexpensive.

  1. Lack of evidence to support policy development for management of contacts of multidrug-resistant tuberculosis patients: two systematic reviews

    NARCIS (Netherlands)

    van der Werf, M. J.; Langendam, M. W.; Sandgren, A.; Manissero, D.

    2012-01-01

    BACKGROUND: Existing international guidelines provide different recommendations for the management of contacts of multidrug-resistant tuberculosis (MDR-TB) patients. OBJECTIVE: To conduct two systematic reviews with the aim of identifying chemoprophylactic approaches that are effective in contacts

  2. Extraction of contact resistance and channel parameters from the electrical characteristics of a single bottom-gate/top-contact organic transistor

    Science.gov (United States)

    Takagaki, Shunsuke; Yamada, Hirofumi; Noda, Kei

    2016-03-01

    A parameter extraction procedure for staggered-type organic field-effect transistors (OFETs), in which only the electrical characteristics of a single device are needed, was newly considered. The existing differential method and the transition voltage method for evaluating contact and channel parameters in OFETs were complementarily combined. The calibration of the total resistance between the source and the drain was also incorporated to compensate discrepancies in the total resistances calculated from output and transfer characteristics, caused by the existence of nonignorable contact resistance and carrier traps. By using our proposed method, gate-voltage-dependent contact resistance and channel mobility in the linear regime were evaluated for bottom-gate/top-contact pentacene thin-film transistors, and the channel-length dependence of these parameters was investigated. A series of results of parameter extraction confirm the validity of our proposed method, which is advantageous in avoiding the influences of characteristic variations that are frequently observed in practical OFET devices.

  3. Intergrain contact density indices for granular mixes—II: Liquefaction resistance

    Science.gov (United States)

    Thevanayagam, S.

    2007-06-01

    Whether the presence of non-plastic silt in a granular mix soil impact its liquefaction potential and how to evaluate liquefaction resistance of sand containing different amounts of silt contents are both controversial issues. This paper presents the results of an experimental evaluation to address these issues. Two parameters, namely, equivalent intergranular void ratio ( e c)eq and equivalent interfine void ratio ( e f)eq, proposed in a companion paper (Thevanayagam, 2007) as indices of active grain contacts in a granular mix, are used to characterize liquefaction resistance of sands and silty sands. Results indicate that, at the same global void ratio ( e), liquefaction resistance of silty sand decreases with an increase in fines content ( C F) up to a threshold value ( C Fth). This is due to a reduction in intergrain contact density between the coarse grains. Beyond C Fth, with further addition of fines, the interfine contacts become significant while the inter-coarse grain contacts diminish and coarse grains become dispersed. At the same e, the liquefaction resistance increases and the soil becomes stronger with a further increase in silt content. Beyond a limiting fines content ( C FL), the liquefaction resistance is controlled by interfine contacts only. When C F resistance of silty sand is comparable to that of the host clean sand at a void ratio equal to ( e c)eq. When C F > C Fth, at the same ( e f)eq, the cyclic strength of a sandy silt is comparable to the host silt at a void ratio equal to ( e f)eq.

  4. Thermal resistance of indium coated sapphire-copper contacts below 0.1 K

    Science.gov (United States)

    Eisel, T.; Bremer, J.; Koettig, T.

    2014-11-01

    High thermal resistances exist at ultra-low temperatures for solid-solid interfaces. This is especially true for pressed metal-sapphire joints, where the heat is transferred by phonons only. For such pressed joints it is difficult to achieve good physical, i.e. thermal contacts due to surface irregularities in the microscopic or larger scale. Applying ductile indium as an intermediate layer reduces the thermal resistance of such contacts. This could be proven by measurements of several researchers. However, the majority of the measurements were performed at temperatures higher than 1 K. Consequently, it is difficult to predict the thermal resistance of pressed metal-sapphire joints at temperatures below 1 K. In this paper the thermal resistances across four different copper-sapphire-copper sandwiches are presented in a temperature range between 30 mK and 100 mK. The investigated sandwiches feature either rough or polished sapphire discs (Ø 20 mm × 1.5 mm) to investigate the phonon scattering at the boundaries. All sandwiches apply indium foils as intermediate layers on both sides of the sapphire. Additionally to the indium foils, thin indium films are vapour deposited onto both sides of one rough and one polished sapphire in order to improve the contact to the sapphire. Significantly different thermal resistances have been found amongst the investigated sandwiches. The lowest total thermal resistivity (roughly 26 cm2 K4/W at 30 mK helium temperature) is achieved across a sandwich consisting of a polished sapphire with indium vapour deposition. The thermal boundary resistance between indium and sapphire is estimated from the total thermal resistivity by assuming the scattering at only one boundary, which is the warm sapphire boundary where phonons impinge, and taking the scattering in the sapphire bulk into account. The so derived thermal boundary resistance agrees at low temperatures very well with the acoustic mismatch theory.

  5. Contact Resistance of Flip-Chip Joints in Wearable Electronic Textiles

    Science.gov (United States)

    Choi, Jung-Yeol; Oh, Tae Sung

    2014-12-01

    Flip-chip bonding to a Cu lead frame transferred to a fabric was achieved by use of a non-conducting adhesive. Average contact resistance of the flip-chip joints was evaluated on variation of the Cu and Sn thickness of Cu/Sn bumps of size 150 × 220 μm2. The total thickness of the Cu/Sn bumps was fixed at 15 μm. The average contact resistance of the flip-chip joints on the fabric was 5.4-10.8 mΩ, depending on the Sn thickness of the Cu/Sn bumps; this was lower than for flip-chip joints on a rigid Si substrate (15.6-26.5 mΩ). The average contact resistance of flip-chip joints on the fabric decreased from 10.8 mΩ to 5.5 mΩ when the chip-bump configuration was changed from 15- μm-thick Sn to 7- μm-thick Cu/8- μm-thick Sn. The contact resistance of flip-chip joints bonded with the 7- μm-thick Cu/8- μm-thick Sn bumps remained below 10 mΩ for up to 750 h in the 85°C/85% relative humidity test and even decreased to below 4 mΩ in the storage test at 125°C for up to 1000 h.

  6. Control of contact resistance by strand surface coating in 36-strands NbTi CICC's

    NARCIS (Netherlands)

    Nijhuis, Arend; ten Kate, Herman H.J.; Duchateau, Jean-Luc; Decool, Patrick

    2001-01-01

    The stability and AC loss of NbTi cable-in-conduit conductors (CICCs) is largely determined by the interstrand contact resistance (Rc). Rc is predominantly established by the strand surface properties. Five 36-strand CICCs, fully identical except for the plating of the strand surface or the presence

  7. Four-terminal resistance in a clean interacting quantum wire with invasive contacts

    Energy Technology Data Exchange (ETDEWEB)

    Aita, H., E-mail: lili@df.uba.ar [Departamento de Fisica, Facultad de Ciencias Exactas-UNLP, CC 67, La Plata 1900 (Argentina); IFLP-CONICET (Argentina); Arrachea, L. [Departamento de Fisica and IFIBA, Universidad de Buenos Aires, Pebellon I, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Naon, C. [Departamento de Fisica, Facultad de Ciencias Exactas-UNLP, CC 67, La Plata 1900 (Argentina); IFLP-CONICET (Argentina)

    2012-08-15

    We investigate the behavior of the four-terminal resistance R{sub 4pt} in an interacting quantum wire described by a Luttinger liquid with an applied bias voltage V and coupled to two voltage probes. We extend previous results, obtained for very weakly coupled contacts, to the case in which the effects of the probes become non-trivially correlated.

  8. Four-terminal resistance in a clean interacting quantum wire with invasive contacts

    Science.gov (United States)

    Aita, H.; Arrachea, L.; Naón, C.

    2012-08-01

    We investigate the behavior of the four-terminal resistance R4pt in an interacting quantum wire described by a Luttinger liquid with an applied bias voltage V and coupled to two voltage probes. We extend previous results, obtained for very weakly coupled contacts, to the case in which the effects of the probes become non-trivially correlated.

  9. A Feasibility Study on the Worn Area Estimation by Measuring a Contact Resistance (I)

    International Nuclear Information System (INIS)

    Lee, Young-Ho; Kim, Hyung-Kyu

    2007-01-01

    In order to improve the fretting wear resistance of the nuclear fuel rod with considering the effect of the contacting spring shape, it is necessary to examine the formation procedure of the worn area during the fretting wear experiments with including its shape, size and the debris removal path. This is because the wear volume and the maximum wear depth are dominantly affected by the worn area and the wear resistance of the nuclear fuel rod was dominantly affected by the spring shape rather than the test environment and the contact mode (i.e. impact, sliding, rubbing, etc.). Unfortunately, it is almost impossible to archive the size and shape of the worn area on real-time basis because the contact surfaces are always hidden. If we could measure the worn area properties during fretting wear tests, it enables us to promptly estimate the wear resistance or behavior with various contacting spring shapes. Generally, fretting wear degradation is generated by the localized plastic deformation, fracture and finally detachment of wear debris. Generally, wear debris easily oxidized by frictional heat, test environment, etc. From the previous studies, most of the wear debris was detached from the worn surface in the distilled water condition while the wear debris in the dry condition remained on or adhered to the worn surface. At this time, it is reasonable that the accumulated wear debris on the worn surface is existed in the form of oxide. If small amount of electric current was applied between the contacting surfaces, wear debris could be an obstacle to flow the electric current. This means that the variation of the contact resistance under constant electric current during the fretting wear tests has much information on the formation of the worn area even though the applying current could accelerate the oxidation of the generated wear debris. So, in this study, fretting wear tests have been performed with applying an electric current in room temperature air in order to

  10. A theoretical model for metal-graphene contact resistance using a DFT-NEGF method.

    Science.gov (United States)

    Ji, Xiang; Zhang, Jinyu; Wang, Yan; Qian, He; Yu, Zhiping

    2013-11-07

    The contact resistance (R(c)) between graphene and metal electrodes is of crucial importance for achieving potentially high performances for graphene devices. However, previous analytical models based on Landauer's approach have failed to include the Fermi velocity difference between the graphene under the metal and the pure graphene channel. Hereby we report a theoretical model to estimate the R(c) using density-functional theory and non-equilibrium Green's function methods. Our model not only presents a clear physical picture of the metal-graphene contacts, but also generates R(c) values which are in good agreement with the experimental results: 210 Ω μm for double-sided Pd contacts compared with 403 Ω μm for single-sided Pd contact.

  11. Rough surface electrical contact resistance considering scale dependent properties and quantum effects

    International Nuclear Information System (INIS)

    Jackson, Robert L.; Crandall, Erika R.; Bozack, Michael J.

    2015-01-01

    The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness

  12. Imaging geological contact utilizing 2D resistivity method for light rail transit (LRT) track alignment

    Science.gov (United States)

    Ali, Nisa'; Saad, Rosli; Muztaza, Nordiana M.; Ismail, Noer E. H.

    2013-05-01

    The purpose of this study was to locate the geological contact using 2D resistivity method for Light Rail Transit (LRT) track alignment. The resistivity method was conducted on eight survey lines with the length of line 1 was 600m. The length of line 2, 3, 4, 5, 6, and 7 were 200m each while line 8 is 115m. All the survey used minimum electrode spacing of 5m and using Pole-dipole array with minimum current is 2mA and maximum was 20mA. The result obtained from the pseudosection showed that the area generally divided into three main zones, fill materials/residual soil with a resistivity value of 2000 Ωm. Three fractured zones were detected along line L1 and a lot of boulders were detected at L1, L3, L4, L5 and L6. The geological contact was between the residual soil and granite bedrock.

  13. Internal resistance of rear totally diffused solar cells with line shaped contacts

    Science.gov (United States)

    Meier, Sebastian; Saint-Cast, Pierre; Wöhrle, Nico; Fell, Andreas; Greulich, Johannes; Wolf, Andreas; Glunz, Stefan W.

    2017-11-01

    We present an analytical model for the internal resistance of passivated emitter and rear totally diffused (PERT) solar cells. First, we apply the model of Saint-Cast for the spreading resistance of a passivated emitter and rear cell (PERC) structure with line-shaped contacts. To account for the additional vertical current flow through the silicon wafer and the lateral current flow through the back surface field of a PERT structure, we add a parallel current path using common analytical expressions. We compare the analytical models with two-dimensional numerical simulations based on Quokka 3 and find deviations of less than 6% for the internal resistance. In addition, we compare the analytical model of the internal resistance of PERC and PERT solar cells with experimental data of the series resistance of PERC and PERT solar cells.

  14. Sex-specific spinosad resistance in Danish houseflies

    DEFF Research Database (Denmark)

    Højland, Dorte Heidi

    Spinosad is a novel insecticide which is useful for control of multiple insect pests and it was introduced for housefly control within the last decade. Prior to the introduction of spinosad in Denmark, a survey of Danish houseflies from farms all over the country was initiated, and we discovered...... a strain that was resistant to spinosad. However, this cross-resistance was unusual because females were 26-fold resistant, while males were only 6-fold resistant. This pattern of resistance does not match any known resistance to other insecticides and is different from spinosad resistance in other...... countries. Discovering the reasons behind this sex specific resistance will shed some light in mechanisms behind spinosad resistance in the housefly....

  15. Contact angle measurement - a reliable supportive method for screening water-resistance of ultraviolet-protecting products in vivo.

    Science.gov (United States)

    Hagens, R; Mann, T; Schreiner, V; Barlag, H G; Wenck, H; Wittern, K-P; Mei, W

    2007-08-01

    Substantivity of sunscreen formulations is affected by the wash-out rate of ultraviolet-absorber and -reflector compounds in water. Water-resistance of sunscreen formulations is currently determined according to a standardized European Cosmetic Toiletry and Perfumery Association (COLIPA) protocol, encompassing the determination of a minimal erythemal dose before and after a defined immersion step in water. It can be supposed that the higher the wettability of a treated skin area, the higher is the wash-out rate of sunscreen compounds. This present report addresses the validity of determining the wettability of treated skin alone as a measure for the water-resistance of sunscreen products. The report addresses the robustness, accuracy and congruence of a recently developed wettability test, based on the measurement of the contact angle (CA) of a sessile water drop on treated skin areas. Contact angle data of 66 sunscreen formulations are compared with the corresponding results of 81 water-resistance tests, using the sun protection factor (SPF)/immersion/SPF method. Sunscreen products tested by the CA method were applied to the skin of the volar forearm of test subjects at a defined dose and drying-time, using a standardized application and recording device. Contact angles between a sessile water drop and skin were recorded by a Charge-Coupled Device (CCD) camera and subjected to automatic contour analysis. Taking the SPF/immersion/SPF method as gold standard, accuracy parameters of the CA method were determined. By using an appropriate cut-off level of CAs, the CA method has a specificity and positive-predictive value of 100%, and turns out to be a reliable screening method to identify water-resistant formulations. Based on our findings, those formulations that give CAs above 30 degrees may be categorized water-proof without further testing by the COLIPA water-resistance method.

  16. A new player in race-specific resistance

    KAUST Repository

    Keller, Beat

    2018-04-04

    Race-specific resistance genes represent essential genetic sources in crop breeding. Map-based cloning of the wheat Stb6 gene against Zymoseptoria tritici identified a wall-associated receptor kinase-like protein as a novel player in race-specific disease resistance.

  17. Effects of ultra-vacuum and space environment on contact ohmic resistance: LDEF experiment AO 138-11

    Science.gov (United States)

    Assie, Jean-Pierre; Perotto, Alfred

    1992-01-01

    The FRECOPA experimentation of chemical resistance of electrical connector contacts, as described, has evidenced the detrimental time variations of nickel plated conductors and gilded copper contacts, irrespective of crimping storage or metal peening conditions. With a view to reorient aluminum technology a silvered aluminum conductor/gilded aluminum contact solution was evaluated.

  18. Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation

    Directory of Open Access Journals (Sweden)

    Filippo Giubileo

    2016-11-01

    Full Text Available We studied the effects of low-energy electron beam irradiation up to 10 keV on graphene-based field effect transistors. We fabricated metallic bilayer electrodes to contact mono- and bi-layer graphene flakes on SiO2, obtaining specific contact resistivity ρ c ≈ 19 k Ω · µ m 2 and carrier mobility as high as 4000 cm2·V−1·s−1. By using a highly doped p-Si/SiO2 substrate as the back gate, we analyzed the transport properties of the device and the dependence on the pressure and on the electron bombardment. We demonstrate herein that low energy irradiation is detrimental to the transistor current capability, resulting in an increase in contact resistance and a reduction in carrier mobility, even at electron doses as low as 30 e−/nm2. We also show that irradiated devices recover their pristine state after few repeated electrical measurements.

  19. Serum vitamin d level and susceptibility to multidrug-resistant tuberculosis among household contacts

    Science.gov (United States)

    Herlina, N.; Sinaga, B. Y. M.; Siagian, P.; Mutiara, E.

    2018-03-01

    Low levels of vitamin D is a predisposing factor for Multidrug-resistant tuberculosis. Family members in contact with the patient are also at risk of infection. Currently, there is no study that compares vitamin D levels between MDR-TB patients and household contact. This study aims to identify the association between level vitamin D within MDR-TB occurrence. This was a case-control study, with the number of samples in each group (MDR-TB) patients and household contactswere40 people. Each member of each group was checked for vitamin D levels using enzyme-linked immunosorbent assay (ELISA) technique. Statistical analysis was by using Chi-Square analysis using SPSS. Mean levels of vitamin D in MDR-TB patients were 32.21, household contact 31.7. There was anosignificant association between vitamin D levels and MDR-TB occurrence (p=1.0).No significant associationbetween vitamin D level with theMDR-TB occurrence.

  20. Plethysmographic measurements of specific airway resistance in young children

    DEFF Research Database (Denmark)

    Bisgaard, Hans; Nielsen, Kim G

    2005-01-01

    Validated methods for lung function measurements in young children are lacking. Plethysmographic measurement of specific airway resistance (sRaw) provides such a method applicable from 2 years of age. sRaw gauges airway resistance from the measurements of the pressure changes driving the airflow ...

  1. Plethysmographic measurements of specific airway resistance in young children

    DEFF Research Database (Denmark)

    Bisgaard, Hans; Nielsen, Kim G

    2005-01-01

    Validated methods for lung function measurements in young children are lacking. Plethysmographic measurement of specific airway resistance (sRaw) provides such a method applicable from 2 years of age. sRaw gauges airway resistance from the measurements of the pressure changes driving the airflow...

  2. Is Chemoprophylaxis for Child Contacts of Drug-Resistant TB Patients Beneficial? A Systematic Review

    Directory of Open Access Journals (Sweden)

    C. Padmapriyadarsini

    2018-01-01

    Full Text Available Background. Preventive therapy for child contacts of multidrug-resistant tuberculosis (MDR-TB patients is poorly studied, and no consensus about the role and the rationale of chemoprophylaxis has been reached. Objective. To conduct systematic review with an aim to determine the effectiveness of TB preventive therapy in reducing the incidence of TB disease in pediatric contacts of MDR-TB patients. Methods. We conducted a literature search for randomized control trials, cohort studies, and case reports of chemoprophylaxis for pediatric contacts of MDR-TB patients in PubMed, EMBASE, Cochrane Databases of Systematic Reviews, metaRegister of Controlled Trials, and other clinical registries through March 2017, using appropriate search strategy. In addition we searched abstracts from international conferences and references of published articles and reviews. Results. Of the 153 references assessed from various databases, seven studies were identified as relevant after adaption of eligibility criteria and assessed for systematic review. Of these, only two studies contributed data for the pooled meta-analysis. Conclusions. Though the available evidences suggest that the chemoprophylaxis for child contacts of MDR-TB patients is beneficial, data to support or reject preventive therapy is very limited. Further clinical research, in Tb endemic settings like India, needs to be performed to prove the beneficial effect of chemoprophylaxis for pediatric contacts of MDR-TB.

  3. Evaluation of the contact angle and frost resistance of hydrophobised heat-insulating mortars with polystyrene

    Science.gov (United States)

    Barnat-Hunek, Danuta; Łagód, Grzegorz; Klimek, Beata

    2017-07-01

    The aim of the research presented in the paper was to evaluate the feasibility of using hydrophobic preparation based on organosilicon compounds for surface protection on the heat-insulating mortars modified with polystyrene. The work discusses issues related to wettability, absorptivity and frost resistance of the surface layer of mortars. The experimental part pertains to the physical and mechanical properties of polystyrene-modified mortars and the influence of hydrophobic preparation on the contact angle and frost resistance. The frost resistance of mortars was examined following 25 cycles of freezing and thawing. The contact angle of light mortars (θw) was determined before and after the tests of frost resistance, in the function of time using a single measurement liquid. This provided a basis for calculating the surface free energy with Neumann method, characterizing the wettability and adhesion of mortars under normal conditions and with damages resulting from frost weathering. The structure of mortars and the adhesion of lightweight aggregate to cement paste were presented by means of scanning electron microscopy. The studies enabled to determine the hydrophobisation efficiency of heat-insulating mortars with polystyrene. The obtained results confirmed the possibility of producing heat-insulating mortars modified with polystyrene along with proper surface protection against moisture and frost.

  4. Thermal resistance of indium coated sapphire–copper contacts below 0.1K

    CERN Document Server

    Eisel, T; Koettig, T

    2014-01-01

    High thermal resistances exist at ultra-low temperatures for solid-solid interfaces. This is especially true for pressed metal-sapphire joints, where the heat is transferred by phonons only. For such pressed joints it is difficult to achieve good physical, i.e. thermal contacts due to surface irregularities in the microscopic or larger scale. Applying ductile indium as an intermediate layer reduces the thermal resistance of such contacts. This could be proven by measurements of several researchers. However, the majority of the measurements were performed at temperatures higher than 1 K. Consequently, it is difficult to predict the thermal resistance of pressed metal-sapphire joints at temperatures below 1 K. In this paper the thermal resistances across four different copper-sapphire-copper sandwiches are presented in a temperature range between 30 mK and 100 mK. The investigated sandwiches feature either rough or polished sapphire discs (empty set 20 mm x 1.5 mm) to investigate the phonon scattering at the bo...

  5. Multivariate analysis and extraction of parameters in resistive RAMs using the Quantum Point Contact model

    Science.gov (United States)

    Roldán, J. B.; Miranda, E.; González-Cordero, G.; García-Fernández, P.; Romero-Zaliz, R.; González-Rodelas, P.; Aguilera, A. M.; González, M. B.; Jiménez-Molinos, F.

    2018-01-01

    A multivariate analysis of the parameters that characterize the reset process in Resistive Random Access Memory (RRAM) has been performed. The different correlations obtained can help to shed light on the current components that contribute in the Low Resistance State (LRS) of the technology considered. In addition, a screening method for the Quantum Point Contact (QPC) current component is presented. For this purpose, the second derivative of the current has been obtained using a novel numerical method which allows determining the QPC model parameters. Once the procedure is completed, a whole Resistive Switching (RS) series of thousands of curves is studied by means of a genetic algorithm. The extracted QPC parameter distributions are characterized in depth to get information about the filamentary pathways associated with LRS in the low voltage conduction regime.

  6. Series Resistance Analysis of Passivated Emitter Rear Contact Cells Patterned Using Inkjet Printing

    Directory of Open Access Journals (Sweden)

    Martha A. T. Lenio

    2012-01-01

    Full Text Available For higher-efficiency solar cell structures, such as the Passivated Emitter Rear Contact (PERC cells, to be fabricated in a manufacturing environment, potentially low-cost techniques such as inkjet printing and metal plating are desirable. A common problem that is experienced when fabricating PERC cells is low fill factors due to high series resistance. This paper identifies and attempts to quantify sources of series resistance in inkjet-patterned PERC cells that employ electroless or light-induced nickel-plating techniques followed by copper light-induced plating. Photoluminescence imaging is used to determine locations of series resistance losses in these inkjet-patterned and plated PERC cells.

  7. A Compact P⁺ Contact Resistance Model for Characterization of Substrate Coupling in Modern Lightly Doped CMOS Processes

    DEFF Research Database (Denmark)

    Shen, Ming; Mikkelsen, Jan H.; Jensen, Ole Kiel

    2012-01-01

    Compact modeling of P+ contact resistances is important for characterization of substrate noise coupling in mixed-signal System on Chips (SoCs). Existing contact resistance models can handle uniformly doped bulk or epitaxial substrates. However, compact contact resistance models feasible for modern......, and it is scalable to layout/substrate parameters. The proposed model can also be used to predict noise coupling in terms of S-parameters. The model validation has been done by both EM simulations and measurements, and satisfactory agreement is found between the modeled and measured resistances as well as S-parameters....... lightly-doped CMOS processes with P-well layers are still unavailable. This paper presents a new compact resistance model aiming at solving this problem. A Conformal Mapping(CM) method was used to derive the closed-form expressions for the resistances in the model. The model requires no fitting factors...

  8. Recovery of resistant bacteria from mattresses of patients under contact precautions.

    Science.gov (United States)

    Viana, Roberta El Hariri; dos Santos, Simone G; Oliveira, Adriana C

    2016-04-01

    Microorganisms may contaminate hospital mattresses even after terminal cleaning. We investigated the recovery of resistant bacteria from the mattresses of patients under contact precautions at a university hospital. We conducted a cross-sectional study. Samples were obtained from the surface of mattresses, spread on replicate organism detection and counting plates, and cultivated at 37°C for 48 hours. After collecting samples, we identified microorganisms and tested for antimicrobial susceptibility using the Vitek 2 (bioMérieux SA, Marcy-l'Etoile, France) automation system. We evaluated 51 mattresses. A total of 26 had resistant bacteria on the surface; the predominant species were Acinetobacter baumannii (69.2%), Klebsiella pneumoniae (11.5%), and Pseudomonas aeruginosa (11.5%). The median length of hospital stay was 41 days; the bed occupancy for patients under contact precautions and the time at which the patient was diagnosed as a carrier of resistant bacteria was 18 days. The phenotypic similarity of A baumannii in inpatient units (mattresses) suggests circulation of the same strain. These results highlight the importance of controlling the potential spread of microorganisms through hospital mattresses. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  9. markers linked to race-specific resistance to Striga gesnerioides

    African Journals Online (AJOL)

    Development of sequence characterized amplified region (SCAR) markers linked to race-specific resistance to Striga gesnerioides in cowpea ( Vigna unguiculata ... a pair of sequence specific primers were designed and used to isolate identical and similar fragments from cowpea genomic DNA of different cowpea lines by ...

  10. An Overview of Dynamic Contact Resistance Measurement of HV Circuit Breakers

    Science.gov (United States)

    Bhole, A. A.; Gandhare, W. Z.

    2016-06-01

    With the deregulation of the electrical power industry, utilities and service companies are operating in a changing business environment. High voltage circuit breakers are extremely important for the function of modern electric power supply systems. The need to predict the proper function of circuit breaker grew over the years as the transmission networks expanded. The maintenance of circuit breakers deserves special consideration because of their importance for routine switching and for protection of other equipments. Electric transmission system breakups and equipment destruction can occur if a circuit breaker fails to operate because of a lack of preventive maintenance. Dynamic Contact Resistance Measurement (DCRM) is known as an effective technique for assessing the condition of power circuit breakers contacts and operating mechanism. This paper gives a general review about DCRM. It discusses the practical case studies on use of DCRM for condition assessment of high voltage circuit breakers.

  11. Characteristics of contact resistance for Ag, Cu and Al spot contact under DC current flow of 300A; Gin, do oyobi arumi tensesshokushi no chokuryu 300A tsudenji ni okeru sesshoku teiko tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Aichi, H. [Daido Institute of Technology, Nagoya (Japan); Matsumura, T. [Nagoya University, Nagoya (Japan); Miyachi, I. [Aichi Inst. of Technology, Aichi (Japan)

    1997-07-01

    The temperature rise of the contact spot by Joule`s heat under high current flow may result in the softening or welding of the contact materials. Contact resistances of Ag, Cu and Al spot contacts have been observed under the current flow of up to 300A DC. The contact resistances of Ag and Cu with clean surfaces were revealed to be kept constant independent of the magnitude of the applied current flow. On the other hand, contact resistances of Al and Cu with oxidized surfaces were greatly reduced with the increasing current flow. 7 refs., 5 figs., 2 tabs.

  12. Specific antigen serologic tests in leprosy: implications for epidemiological surveillance of leprosy cases and household contacts

    Directory of Open Access Journals (Sweden)

    Ana Paula Mendes Carvalho

    Full Text Available BACKGROUND There is a lack of straightforward tests for field application and known biomarkers for predicting leprosy progression in infected individuals. OBJECTIVE The aim was to analyse the response to infection by Mycobacterium leprae based on the reactivity of specific antigens: natural disaccharide linked to human serum albumin via an octyl (NDOHSA, a semisynthetic phenolic glycolipid-I (PGL-I; Leprosy Infectious Disease Research Institute Diagnostic-1 (LID-1 and natural disaccharide octyl - Leprosy Infectious Disease Research Institute Diagnostic-1 (NDOLID. METHODS The study population consisted of 130 leprosy cases diagnosed between 2010 and 2015 and 277 household contacts. An enzyme-linked immunosorbent assay (ELISA was used to analyse the reactivity of antibodies against NDOHSA, LID-1 and NDOLID. The samples and controls were tested in duplicate, and the antibody titer was expressed as an ELISA index. Data collection was made by home visits with application of questionnaire and dermatological evaluation of all household contacts to identify signs and symptoms of leprosy. FINDINGS Significant differences in the median ELISA results were observed among leprosy cases in treatment, leprosy cases that had completed treatment and household contacts. Higher proportions of seropositivity were observed in leprosy cases in treatment. Seropositivity was also higher in multibacillary in relation to paucibacillary, with the difference reaching statistical significance. Lower titers were observed among cases with a longer treatment time or discharge. For household contacts, the differences according to the clinical characteristics of the leprosy index case were less pronounced than expected. Other factors, such as the endemicity of leprosy, exposure outside the residence and genetic characteristics, appeared to have a greater influence on the seropositivity. MAIN CONCLUSIONS Serologic tests could be used as auxiliary tools for determining the

  13. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan

    2016-12-29

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a method includes preparing a pretreated target area on a CFRP composite surface using laser pulsed irradiation and bonding an electrode to exposed fibers in the pretreated target area. The surface preparation can allow the electrode to have a low contact resistance with the CFRP composite.

  14. Analysis of charge injection and contact resistance as a function of electrode surface treatment in ambipolar polymer transistors

    Science.gov (United States)

    Lee, Seon Jeng; Kim, Chaewon; Jung, Seok-Heon; Di Pietro, Riccardo; Lee, Jin-Kyun; Kim, Jiyoung; Kim, Miso; Lee, Mi Jung

    2018-01-01

    Ambipolar organic field-effect transistors (OFETs) have both of hole and electron enhancements in charge transport. The characteristics of conjugated diketopyrrolopyrrole ambipolar OFETs depend on the metal-contact surface treatment for charge injection. To investigate the charge-injection characteristics of ambipolar transistors, these devices are processed via various types of self-assembled monolayer treatments and annealing. We conclude that treatment by the self-assembled monolayer 1-decanethiol gives the best enhancement of electron charge injection at both 100 and 300 °C annealing temperature. In addition, the contact resistance is calculated by using two methods: One is the gated four-point probe (gFPP) method that gives the voltage drop between channels, and the other is the simultaneous contact resistance extraction method, which extracts the contact resistance from the general transfer curve. We confirm that the gFPP method and the simultaneous extraction method give similar contact resistance, which means that we can extract contact resistance from the general transfer curve without any special contact pattern. Based on these characteristics of ambipolar p- and n-type transistors, we fabricate inverter devices with only one active layer. [Figure not available: see fulltext.

  15. The effect of thermal contact resistance on the thermosetting pultrusion process

    DEFF Research Database (Denmark)

    Baran, Ismet; Tutum, Cem Celal; Hattel, Jesper Henri

    2013-01-01

    In the present study the control volume based finite difference (CV/FD) method is utilized to perform thermo-chemical simulation of the pultrusion process of a composite rod. Preliminary, the model is applied for a simple setup without die and heaters and the results match well with those obtained...... experimentally in the literature. In order to study the effects of the thermal contact resistance (TCR), which can also be expressed by the heat transfer coefficient (HTC), on the pultrusion process, a cylindrical die block and heaters are added to the original problem domain. The significance of using the TCR...

  16. Mechanical and electrical contact resistance characteristics of a cellular assembly of carbon nanotubes

    International Nuclear Information System (INIS)

    Kiran, M S R N; Ramamurty, U; Misra, Abha

    2013-01-01

    We employ nanoindentation coupled with electrical contact resistance measurements for simultaneous characterization of the electrical and mechanical behaviors of a cellular assembly of carbon nanotubes (CNTs). Experimental results reveal two different responses that correspond to relatively dense and porous regions of the cellular structure. Distinct nonlinear electron transport characteristics are observed, which mainly originate from diffusive conductance in the CNT structure. In the denser region, differential conductance shows asymmetric minima at lower bias, implying that conductivity mainly results from bulk tunneling. However, the porous regions show insignificant differential conduction as opposed to the denser region. (paper)

  17. Stability of Nb-Ti Rutherford Cables Exhibiting Different Contact Resistances

    CERN Document Server

    Willering, G P; Kaugerts, J; ten Kate, H H J

    2008-01-01

    Dipole magnets for the so-called SIS-300 heavy-ion synchrotron at GSI are designed to generate 6 T with a field sweep rate of 1 T/s. It is foreseen to wind the magnets with a 36 strands Nb-Ti Rutherford cable. An important issue in the cable design is sufficiently low AC loss and stability as well. In order to keep the AC loss at low level, the contact resistance between crossing strands Rc is kept high by putting a stainless steel core in the cable. The contact resistance between adjacent strands Ra is controlled by oxidation of the Sn-Ag coating of the strands, like in the LHC. In order to investigate the effect of Ra on the stability of the cable, we prepared four samples with different Ra by varying the heat treatment and applying a soldering technique, resulting in values between 1 mW to 9 mW. The stability of each sample against transient point-like heat pulses was measured. The results of the stability experiments and a comparison with calculations using the network model CUDI are presented...

  18. Minimization of contact resistance between metal and polymer by surface doping

    International Nuclear Information System (INIS)

    Mukherjee, A K; Thakur, A K; Takashima, W; Kaneto, K

    2007-01-01

    The technique of surface doping is used to reduce the contact resistance between Au and poly(3-hexylthiophen-2,5-diyl) (P3HT) in Au(bottom)/P3HT/Au(top) sandwich type cells. To implement this technique, dodecyl benzene sulfonic acid (DBSA) is found to be an effective bulky dopant of P3HT as confirmed by four probe conductivity measurements, absorption and photoluminescence spectra. Sandwich cells treated with DBSA showed electrical short due to diffusion of DBSA across the P3HT film in Au(bottom)/DBSA/P3HT/DBSA/Au(top) sandwich cells, which confirms that DBSA is not immobilized at the surface. To restrict DBSA primarily at the surface, an aqueous solution of poly(ethylenedioxy thiophene) stabilized in poly(styrene sulfonic acid) (PEDOT : PSS) is utilized to make an emulsion with DBSA. The application of this emulsion at the top and bottom Au/P3HT interface has resulted in a decrease of contact resistance by nearly four orders of magnitude

  19. Minimization of contact resistance between metal and polymer by surface doping

    Science.gov (United States)

    Mukherjee, A. K.; Thakur, A. K.; Takashima, W.; Kaneto, K.

    2007-03-01

    The technique of surface doping is used to reduce the contact resistance between Au and poly(3-hexylthiophen-2,5-diyl) (P3HT) in Au(bottom)/P3HT/Au(top) sandwich type cells. To implement this technique, dodecyl benzene sulfonic acid (DBSA) is found to be an effective bulky dopant of P3HT as confirmed by four probe conductivity measurements, absorption and photoluminescence spectra. Sandwich cells treated with DBSA showed electrical short due to diffusion of DBSA across the P3HT film in Au(bottom)/DBSA/P3HT/DBSA/Au(top) sandwich cells, which confirms that DBSA is not immobilized at the surface. To restrict DBSA primarily at the surface, an aqueous solution of poly(ethylenedioxy thiophene) stabilized in poly(styrene sulfonic acid) (PEDOT : PSS) is utilized to make an emulsion with DBSA. The application of this emulsion at the top and bottom Au/P3HT interface has resulted in a decrease of contact resistance by nearly four orders of magnitude.

  20. Potential resistant morphotypes of Acanthamoeba castellanii expressed in multipurpose contact lens disinfection systems.

    Science.gov (United States)

    Ahearn, Donald G; Simmons, Robert B; Ward, Michael A; Stulting, R Doyle

    2012-11-01

    The free-living amoeba Acanthamoeba castellanii is a rare cause of contact lens-associated microbial keratitis. The cyst stage of this amoeba is noted for its resistance to disinfection by multipurpose contact lens solutions (MPS). This report examines and reviews the potential survival modes of A. castellanii in MPS. Trophozoites of A. castellanii (ATCC 30234) at densities from 10 to near 10 were incubated in 3 different MPS in a laminar flow hood for 24 hours at ambient temperatures. The dried films of MPS and phosphate-buffered saline (PBS) controls were examined before and after the addition of a peptone-yeast extract-glucose recovery broth (PYG) for the presence of amoeboid trophozoites and resistance stages over at least 7 days. The parallel exposure of trophozoites to MPS without evaporation or addition of PYG was similarly examined. Amoeboid trophozoites were not recovered in PYG nor were cyst-like structures observed in any MPS with near 10 densities. Progressively with 10 to 10 trophozoites, varied survival modes, particularly aggregates of trophozoites associated with cyst-like structures and occasional amoeboid forms and double-walled cysts with ostioles, became more evident. These morphotypes were most prominent after evaporation and typically first observed in the PYG. Trophozoites of A. castellanii near 10 and progressively to 10 densities are capable of expressing a variety of "short-term" survival modes in MPS, notably with the added stress of evaporation. Expression of these alternate survival modes in MPS may relate, in part, to contamination of contact lens cases and difficulties in developing standardized MPS efficacy tests.

  1. Contact resistance asymmetry of amorphous indium-gallium-zinc-oxide thin-film transistors by scanning Kelvin probe microscopy

    Science.gov (United States)

    Chen-Fei, Wu; Yun-Feng, Chen; Hai, Lu; Xiao-Ming, Huang; Fang-Fang, Ren; Dun-Jun, Chen; Rong, Zhang; You-Dou, Zheng

    2016-05-01

    In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain (S/D) series resistance in operating amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metal-semiconductor junction. Project supported by the Key Industrial R&D Program of Jiangsu Province, China (Grant No. BE2015155), the Priority Academic Program Development of Higher Education Institutions of Jiangsu Province, China, and the Fundamental Research Funds for the Central Universities, China (Grant No. 021014380033).

  2. The Role of III-V Substrate Roughness and Deoxidation Induced by Digital Etch in Achieving Low Resistance Metal Contacts

    Directory of Open Access Journals (Sweden)

    Florent Ravaux

    2017-06-01

    Full Text Available To achieve low contact resistance between metal and III-V material, transmission-line-model (TLM structures of molybdenum (Mo were fabricated on indium phosphide (InP substrate on the top of an indium gallium arsenide (InGaAs layer grown by molecular beam epitaxy. The contact layer was prepared using a digital etch procedure before metal deposition. The contact resistivity was found to decrease significantly with the cleaning process. High Resolution Transmission & Scanning Electron Microscopy (HRTEM & HRSTEM investigations revealed that the surface roughness of treated samples was increased. Further analysis of the metal-semiconductor interface using Energy Electron Loss Spectroscopy (EELS showed that the amount of oxides (InxOy, GaxOy or AsxOy was significantly decreased for the etched samples. These results suggest that the low contact resistance obtained after digital etching is attributed to the combined effects of the induced surface roughness and oxides removal during the digital etch process.

  3. Effect of electroless nickel on the series resistance of high-efficiency inkjet printed passivated emitter rear contacted solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lenio, Martha A.T. [REC Technology US, Inc., 1159 Triton Dr., Foster City, CA 94301 (United States); Lennon, A.J.; Ho-Baillie, A.; Wenham, S.R. [ARC Photovoltaics Centre of Excellence, University of NSW, Sydney, NSW 2052 (Australia)

    2010-12-15

    Many existing and emerging solar cell technologies rely on plated metal to form the front surface contacts, and aluminium to form the rear contact. Interactions between the metal plating solutions and the aluminium rear can have a significant impact on cell performance. This paper describes non-uniform nickel deposition on the sintered aluminium rear surface of passivated emitter and rear contacted (PERC) cells patterned using an inkjet printing technique. Rather than being plated homogeneously over the entire rear surface as is observed on an alloyed aluminium rear, the nickel is plated only in the vicinity of the point openings in the rear surface silicon dioxide dielectric layer. Furthermore, this non-uniform nickel deposition was shown to increase the contact resistance of the rear point contacts by an order of magnitude, resulting in higher series resistance values for these fabricated PERC cells. (author)

  4. Characterization of Contact and Bulk Thermal Resistance of Laminations for Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Cousineau, J. Emily [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bennion, Kevin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); DeVoto, Doug [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mihalic, Mark [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-06-30

    The ability to remove heat from an electric machine depends on the passive stack thermal resistances within the machine and the convective cooling performance of the selected cooling technology. This report focuses on the passive thermal design, specifically properties of the stator and rotor lamination stacks. Orthotropic thermal conductivity, specific heat, and density are reported. Four materials commonly used in electric machines were tested, including M19 (29 and 26 gauge), HF10, and Arnon 7 materials.

  5. Direct observation of contact and channel resistance in pentacene four-terminal thin-film transistor patterned by laser ablation method

    International Nuclear Information System (INIS)

    Yagi, Iwao; Tsukagoshi, Kazuhito; Aoyagi, Yoshinobu

    2004-01-01

    We established a dry-etching patterning process for the channel formation of pentacene thin-film transistor, and fabricated a four-terminal device equipped with a gate electrode. The four-terminal device enabled us to divide two-terminal source-drain resistance into two components of contact resistance and pentacene channel resistance. We obtained direct evidence of a gate-voltagedependent contact resistance change: the gate-induced charge significantly reduced the contact resistance and increased source-drain current. Furthermore, the temperature dependence of the device clearly indicated that the contact resistance was much higher than the channel resistance and was dominated in the two-terminal total resistance of the device below 120 K. An observed activation energy of 80 meV for contact resistance was higher than that of 42 meV for pentacene channel resistance

  6. Fabrication of low specific resistance ceramic carbon composites by ...

    Indian Academy of Sciences (India)

    2017-09-07

    Sep 7, 2017 ... the produced carbon is responsible for low electrical specific resistance of the ceramic carbon composites. References. [1] Takahashi M, Adachi K, Menchavez R L and Fuji M 2006 J. Mater. Sci. 41 1965. [2] ShuKMandTuGC2003Int. J. Machine Tools Manufacture43. 845. [3] Mikeska K R 1997 United States ...

  7. An organ-specific view on nonhost resistance

    Directory of Open Access Journals (Sweden)

    Roxana eStrugala

    2015-07-01

    Full Text Available Nonhost resistance (NHR is the resistance of plants to a plethora of non-adapted pathogens and is considered as one of the most robust resistance mechanisms of plants. Studies have shown that the efficiency of resistance in general and NHR in particular could vary in different plant organs, thus pointing to tissue-specific determinants. This was exemplified by research on host and nonhost interactions of the fungal plant pathogen Magnaporthe oryzae with rice and Arabidopsis, respectively. Thus, rice roots were shown to be impaired in resistance to M. oryzae isolates to which leaves of the same rice cultivar are highly resistant. Moreover, roots of Arabidopsis are also accessible to penetration by M. oryzae while leaves of this nonhost plant cannot be infected. We addressed the question whether or not other plant tissues such as the reproductive system also differ in NHR compared to leaves. Inoculation experiments on wheat with different Magnaporthe species forming either a host or nonhost type of interaction revealed that NHR was as effective on spikes as on leaves. This finding might pave the way for combatting M. oryzae disease on wheat spikes which has become a serious threat especially in South America.

  8. Contact Bioassays with Phenoxybenzyl and Tetrafluorobenzyl Pyrethroids against Target-Site and Metabolic Resistant Mosquitoes.

    Directory of Open Access Journals (Sweden)

    Sebastian Horstmann

    Full Text Available Mosquito strains that exhibit increased tolerance to the chemical class of compounds with a sodium channel modulator mode of action (pyrethroids and pyrethrins are typically described as "pyrethroid resistant". Resistance to pyrethroids is an increasingly important challenge in the control of mosquito-borne diseases, such as malaria or dengue, because one of the main interventions (the distribution of large numbers of long-lasting insecticide-treated bed nets currently relies entirely on long-lasting pyrethroids. Increasing tolerance of target insects against this class of insecticides lowers their impact in vector control. The current study suggests that the level of metabolic resistance depends on the structure of the molecule and that structurally different compounds may still be effective because detoxifying enzymes are unable to bind to these uncommon structures.Treated surface contact bioassays were performed on susceptible Aedes aegypti, East African knockdown resistance (kdr Anopheles gambiae (strain RSP-H and metabolically resistant Anopheles funestus (strain FUMOZ-R with different pyrethroids, such as cypermethrin, ß-cyfluthrin, deltamethrin, permethrin and transfluthrin (alone and in combination with the synergist piperonyl butoxide. The nonfluorinated form of transfluthrin was also assessed as a single agent and in combination with piperonyl butoxide.Although the dosages for pyrethroids containing a phenoxybenzyl moiety have exhibited differences in terms of effectiveness among the three tested mosquito species, the structurally different transfluthrin with a polyfluorobenzyl moiety remained active in mosquitoes with upregulated P450 levels. In trials with transfluthrin mixed with piperonyl butoxide, the added synergist exhibited no efficacy-enhancing effect.The results of this study suggest that transfluthrin has the potential to control P450-mediated metabolically resistant mosquitoes because the structural formula of

  9. Contact Bioassays with Phenoxybenzyl and Tetrafluorobenzyl Pyrethroids against Target-Site and Metabolic Resistant Mosquitoes.

    Science.gov (United States)

    Horstmann, Sebastian; Sonneck, Rainer

    2016-01-01

    Mosquito strains that exhibit increased tolerance to the chemical class of compounds with a sodium channel modulator mode of action (pyrethroids and pyrethrins) are typically described as "pyrethroid resistant". Resistance to pyrethroids is an increasingly important challenge in the control of mosquito-borne diseases, such as malaria or dengue, because one of the main interventions (the distribution of large numbers of long-lasting insecticide-treated bed nets) currently relies entirely on long-lasting pyrethroids. Increasing tolerance of target insects against this class of insecticides lowers their impact in vector control. The current study suggests that the level of metabolic resistance depends on the structure of the molecule and that structurally different compounds may still be effective because detoxifying enzymes are unable to bind to these uncommon structures. Treated surface contact bioassays were performed on susceptible Aedes aegypti, East African knockdown resistance (kdr) Anopheles gambiae (strain RSP-H) and metabolically resistant Anopheles funestus (strain FUMOZ-R) with different pyrethroids, such as cypermethrin, ß-cyfluthrin, deltamethrin, permethrin and transfluthrin (alone and in combination with the synergist piperonyl butoxide). The nonfluorinated form of transfluthrin was also assessed as a single agent and in combination with piperonyl butoxide. Although the dosages for pyrethroids containing a phenoxybenzyl moiety have exhibited differences in terms of effectiveness among the three tested mosquito species, the structurally different transfluthrin with a polyfluorobenzyl moiety remained active in mosquitoes with upregulated P450 levels. In trials with transfluthrin mixed with piperonyl butoxide, the added synergist exhibited no efficacy-enhancing effect. The results of this study suggest that transfluthrin has the potential to control P450-mediated metabolically resistant mosquitoes because the structural formula of transfluthrin differs

  10. Whole-genome comparison of meticillin-resistant Staphylococcus aureus CC22 SCCmecIV from people and their in-contact pets.

    Science.gov (United States)

    Loeffler, Anette; McCarthy, Alex; Lloyd, David H; Musilová, Eva; Pfeiffer, Dirk U; Lindsay, Jodi A

    2013-10-01

    Meticillin-resistant Staphylococcus aureus (MRSA) infections remain important medical and veterinary challenges. The MRSA isolated from dogs and cats typically belong to dominant hospital-associated clones, in the UK mostly EMRSA-15 (CC22 SCCmecIV), suggesting original human-to-animal transmission. Nevertheless, little is known about host-specific genetic variation within the same S. aureus lineage. To identify host-specific variation amongst MRSA CC22 SCCmecIV by comparing isolates from pets with those from in-contact humans using whole-genome microarray. Six pairs of MRSA CC22 SCCmecIV from human carriers (owners and veterinary staff) and their respective infected in-contact pets were compared using a 62-strain whole-genome S. aureus microarray (SAM-62). The presence of putative host-specific genes was subsequently determined in a larger number of human (n = 47) and pet isolates (n = 93) by PCR screening. Variation in mobile genetic elements (MGEs) occurred frequently and appeared largely independent of host and in-contact pair. A plasmid (SAP078A) encoding heavy-metal resistance genes (arsR, arsA, cadA, cadC, mco and copB) was found in three of six human and none of six animal isolates. However, only two of four resistance genes were associated with human hosts (P = 0.015 for arsA and cadA). The variation found amongst MGEs highlights that genetic adaptation in MRSA continues. However, host-specific MGEs were not detected, which supports the hypothesis that pets may not be natural hosts of MRSA CC22 and emphasizes that rigorous hygiene measures are critical to prevent contamination and infection of dogs and cats. The host specificity of individual heavy-metal resistance genes warrants further investigation into different selection pressures in humans and animals. © 2013 ESVD and ACVD.

  11. Theoretical study of potential performance of armchair graphene nanoribbon field effect transistors: Dependence on channel dimensions and contact resistance

    Science.gov (United States)

    Hur, Ji-Hyun; Kim, Deok-kee

    2017-12-01

    In this paper, we examine the performance limitations of graphene nanoribbon field effect transistors (GNRFETs) with various channel dimensions and electrode contact resistances. To do this, we formulate a self-consistent non-equilibrium Green's function method in conjunction with the Poisson equation. We model the behavior of GNRFETs with nanometer dimensions and relatively large bandgaps operating as metal-oxide-semiconductor field effect transistors (MOSFETs) and calculate their performance including contact resistance effects typically occurring at the graphene nanoribbon (GNR) channel and electrodes. We propose a metric for GNRFETs to compete with the current silicon CMOS high performance or low power devices and explain that this can vary significantly depending on the contact resistance.

  12. Controllable Organic Resistive Switching Achieved by One-Step Integration of Cone-Shaped Contact.

    Science.gov (United States)

    Ling, Haifeng; Yi, Mingdong; Nagai, Masaru; Xie, Linghai; Wang, Laiyuan; Hu, Bo; Huang, Wei

    2017-09-01

    Conductive filaments (CFs)-based resistive random access memory possesses the ability of scaling down to sub-nanoscale with high-density integration architecture, making it the most promising nanoelectronic technology for reclaiming Moore's law. Compared with the extensive study in inorganic switching medium, the scientific challenge now is to understand the growth kinetics of nanoscale CFs in organic polymers, aiming to achieve controllable switching characteristics toward flexible and reliable nonvolatile organic memory. Here, this paper systematically investigates the resistive switching (RS) behaviors based on a widely adopted vertical architecture of Al/organic/indium-tin-oxide (ITO), with poly(9-vinylcarbazole) as the case study. A nanoscale Al filament with a dynamic-gap zone (DGZ) is directly observed using in situ scanning transmission electron microscopy (STEM) , which demonstrates that the RS behaviors are related to the random formation of spliced filaments consisting of Al and oxygen vacancy dual conductive channels growing through carbazole groups. The randomicity of the filament formation can be depressed by introducing a cone-shaped contact via a one-step integration method. The conical electrode can effectively shorten the DGZ and enhance the localized electric field, thus reducing the switching voltage and improving the RS uniformity. This study provides a deeper insight of the multiple filamentary mechanisms for organic RS effect. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Fabrication of robot head module using contact resistance force sensor for human robot interaction and its evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Ki; Kim, Jong Ho [Korea Reserch Institute of Standards and Science, Daejeon (Korea, Republic of); Kwon, Hyun Joon [Univ. of Maryland, Maryland (United States); Kwon, Young Ha [Kyung Hee Univ., Gyunggi Do (Korea, Republic of)

    2012-10-15

    This paper presents a design of a robot head module with touch sensing algorithms that can simultaneously detect contact force and location. The module is constructed with a hemisphere and three sensor units that are fabricated using contact resistance force sensors. The surface part is designed with the hemisphere that measures 300 mm in diameter and 150 mm in height. Placed at the bottom of the robot head module are three sensor units fabricated using a simple screen printing technique. The contact force and the location of the model are evaluated through the calibration setup. The experiment showed that the calculated contact positions almost coincided with the applied load points as the contact location changed with a location error of about {+-}8.67 mm. The force responses of the module were evaluated at two points under loading and unloading conditions from 0 N to 5 N. The robot head module showed almost the same force responses at the two points.

  14. Reducing the contact resistance in bottom-contact-type organic field-effect transitors using an AgO x interface layer

    Science.gov (United States)

    Minagawa, Masahiro; Kim, Yeongin; Claus, Martin; Bao, Zhenan

    2017-09-01

    Bottom-contact organic field-effect transistors (OFETs) are prepared by inserting an AgO x layer between a pentacene layer and the source-drain electrodes. The contact resistance in the device is ˜8.1 kΩ·cm with an AgO x layer oxidized for 60 s but reaches 116.9 kΩ·cm with a non-oxidized Ag electrode. The drain current and mobility in the OFETs with the AgO x layer increase with the oxidization time and then gradually plateau, and this trend strongly depends on the work function of the Ag surface. Further, the hole injection is enhanced by the presence of Ag2O but inhibited by the presence of AgO.

  15. Exploring surface cleaning strategies in hospital to prevent contact transmission of methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Lei, Hao; Jones, Rachael M; Li, Yuguo

    2017-01-18

    Cleaning of environmental surfaces in hospitals is important for the control of methicillin-resistant Staphylococcus aureus (MRSA) and other hospital-acquired infections transmitted by the contact route. Guidance regarding the best approaches for cleaning, however, is limited. In this study, a mathematical model based on ordinary differential equations was constructed to study MRSA concentration dynamics on high-touch and low-touch surfaces, and on the hands and noses of two patients (in two hospitals rooms) and a health care worker in a hypothetical hospital environment. Two cleaning interventions - whole room cleaning and wipe cleaning of touched surfaces - were considered. The performance of the cleaning interventions was indicated by a reduction in MRSA on the nose of a susceptible patient, relative to no intervention. Whole room cleaning just before first patient care activities of the day was more effective than whole room cleaning at other times, but even with 100% efficiency, whole room cleaning only reduced the number of MRSA transmitted to the susceptible patient by 54%. Frequent wipe cleaning of touched surfaces was shown to be more effective that whole room cleaning because surfaces are rapidly re-contaminated with MRSA after cleaning. Wipe cleaning high-touch surfaces was more effective than wipe cleaning low-touch surfaces for the same frequency of cleaning. For low wipe cleaning frequency (≤3 times per hour), high-touch surfaces should be targeted, but for high wipe cleaning frequency (>3 times per hour), cleaning should target high- and low-touch surfaces in proportion to the surface touch frequency. This study reproduces the observations from a field study of room cleaning, which provides support for the validity of our findings. Daily whole room cleaning, even with 100% cleaning efficiency, provides limited reduction in the number of MRSA transmitted to susceptible patients via the contact route; and should be supplemented with frequent targeted

  16. Evaluation of Double Process Lithography (DPL) with bi-layer photo-resist process for contact layer-patterning

    Science.gov (United States)

    Chen, Gong; Wu, Kevin

    2008-10-01

    Double Process Lithography (DPL) has been widely accepted as a viable printing technique for critical layers at 45nm nodes and below. In addition, DPL technique also allows us to use available process tool-sets with less capability to develop the next node CMOS devices in early research and development stages with additional photo-masks. One practical issue of applying DPL technique is the process crosstalk, which is the impact of the existing etched patterns after the 1st process to the overall lithography performance during the 2nd printing process. In this paper, we evaluated the DPL process for contact holetype patterning with a 193nm silicon-containing bi-layer photo-resist. We explained the bi-layer photoresist process flow and its low process cross-talk characteristics when applied in our DPL process. We also discussed the challenges of printing small contacts in the DPL process. The preliminary experiment results indicated that silicon-containing photo-resist process is a good candidate for DPL process in the contact hole-type of patterns, and it has good characteristics of low process cross-talk. The flexibility of the drydevelop process in bi-layer resist also offered us another way to form small contacts in the substrate film. At the end, we provided some suggestions in contact pattern decomposition algorithm and related exposure-tool alignment strategies for future implementation of DPL technology.

  17. Immune responses to the Mycobacterium tuberculosis-specific antigen ESAT-6 signal subclinical infection among contacts of tuberculosis patients

    DEFF Research Database (Denmark)

    Doherty, T Mark; Demissie, Abebech; Olobo, Joseph

    2002-01-01

    Diagnosis of latent Mycobacterium tuberculosis infection is considered essential for tuberculosis control but is hampered by the lack of specific reagents. We report that strong recognition of tuberculosis complex-specific antigen ESAT-6 by healthy household contacts of tuberculosis patients...

  18. Experimental investigation of the contact resistance of Graphene/MoS2 interface treated with O2 plasma

    Science.gov (United States)

    Lu, Qin; Liu, Yan; Han, Genquan; Fang, Cizhe; Shao, Yao; Zhang, Jincheng; Hao, Yue

    2018-02-01

    High contact resistance has been a major bottleneck for MoS2 to achieve high performances among two-dimensional material based optoelectronic and electronic devices. In this study, we investigate the contact resistances of different layered graphene film with MoS2 film with Ti/Au electrodes under different O2 plasma treatment time using the circular transmission line model (CTLM). Annealing process followed O2 plasma process to reduce the oxygen element introduced. Raman and X-ray photoelectric spectroscopy were used to analyze the quality of the materials. Finally, the current and voltage curve indicates good linear characteristics. Under the optimized condition of the O2 plasma treatment, a relatively low contact resistance (∼35.7 Ohm mm) without back gate voltage in single-layer graphene/MoS2 structure at room temperature was achieved compared with the existing reports. This method of introducing graphene as electrodes for MoS2 film demonstrates a remarkable ability to improve the contact resistance, without additional channel doping for two-dimensional materials based devices, which paves the way for MoS2 to be a more promising channel material in optoelectronic and electronic integration.

  19. Impact of semiconductor/metal interfaces on contact resistance and operating speed of organic thin film transistors

    KAUST Repository

    Wondmagegn, Wudyalew T.

    2010-09-24

    The contact resistance of field effect transistors based on pentacene and parylene has been investigated by experimental and numerical analysis. The device simulation was performed using finite element two-dimensional drift-diffusion simulation taking into account field-dependent mobility, interface/bulk trap states and fixed charge density at the organic/insulator interface. The width-normalized contact resistance extracted from simulation which included an interface dipole layer between the gold source/drain electrodes and pentacene was 91 kΩcm. However, contact resistance extracted from the simulation, without consideration of interface dipole was 52.4 kΩcm, which is about half of the experimentally extracted 108 kΩcm. This indicates that interface dipoles are critical effects which degrade performances of organic field effect transistors by increasing the contact resistance. Using numerical calculations and circuit simulations, we have predicted a 1 MHz switching frequency for a 1 μm channel length transistor without dipole interface between gold and pentacene. The transistor with dipole interface is predicted, via the same methods, to exhibit an operating frequency of less than 0.5 MHz. © 2010 Springer Science+Business Media LLC.

  20. A physics-based model of gate-tunable metal–graphene contact resistance benchmarked against experimental data

    International Nuclear Information System (INIS)

    Chaves, Ferney A; Jiménez, David; Sagade, Abhay A; Neumaier, Daniel; Kim, Wonjae; Riikonen, Juha; Lipsanen, Harri

    2015-01-01

    Metal–graphene contact resistance is a technological bottleneck in the realization of viable graphene-based electronics. We report a model that is useful for finding the gate-tunable components of this resistance, determined by the tunneling of carriers between the 3D metal and 2D graphene underneath, followed by Klein tunneling to the graphene in the channel. This model quantifies the intrinsic factors that control that resistance, including the effect of unintended chemical doping. Our results agree with experimental results for several metals. (paper)

  1. Degowning the controversies of contact precautions for methicillin-resistant Staphylococcus aureus: A review.

    Science.gov (United States)

    Kullar, Ravina; Vassallo, Angela; Turkel, Sarah; Chopra, Teena; Kaye, Keith S; Dhar, Sorabh

    2016-01-01

    Contact precautions (CPs) are recommended to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission in institutions. Rising doubts about CP effectiveness and recognition of unintended consequences for patients have raised questions about the benefit. The objective of this study was to evaluate the effectiveness and adverse outcomes associated with CPs for prevention of MRSA transmission. We searched PubMed, Embase, and the Cochrane Library for articles related to effectiveness and adverse outcomes of CPs in patients with MRSA. Criteria for inclusion included the following: articles conducted in the United States, articles performed in an acute care setting, articles that were not a case series or review, and those with standardized collection of data or inclusion of case and control groups. Results were summarized and examined for potential limitations. Recommendations were based on our findings. CPs reduced MRSA transmission in epidemic settings and in instances with high compliance, but a decrease in infection rates was not shown. Unintended consequences of CPs include decreased health care provider (HCP) time spent with patients, low HCP compliance, decreased perceptions of comfort from patients, and greater likelihood of patient complaints and negative psychologic implications. In endemic settings, there are few data to support routine use of CPs to control the spread of MRSA. Education should be performed in hospitals to improve patients' perception of care and understanding of CPs when implemented and HCPs' adherence to good hand hygiene and standard precautions practices. Published by Elsevier Inc.

  2. Pinhole density and contact resistivity of carrier selective junctions with polycrystalline silicon on oxide

    Science.gov (United States)

    Wietler, T. F.; Tetzlaff, D.; Krügener, J.; Rienäcker, M.; Haase, F.; Larionova, Y.; Brendel, R.; Peibst, R.

    2017-06-01

    In the pursuit of ever higher conversion efficiencies for silicon photovoltaic cells, polycrystalline silicon (poly-Si) layers on thin silicon oxide films were shown to form excellent carrier-selective junctions on crystalline silicon substrates. Investigating the pinhole formation that is induced in the thermal processing of the poly-Si on oxide (POLO) junctions is essential for optimizing their electronic performance. We observe the pinholes in the oxide layer by selective etching of the underlying crystalline silicon. The originally nm-sized pinholes are thus readily detected using simple optical and scanning electron microscopy. The resulting pinhole densities are in the range of 6.6 × 106 cm-2 to 1.6 × 108 cm-2 for POLO junctions with selectivities close to S10 = 16, i.e., saturation current density J0c below 10 fA/cm2 and contact resistivity ρc below 10 mΩcm2. The measured pinhole densities agree with values deduced by a pinhole-mediated current transport model. Thus, we conclude pinhole-mediated current transport to be the dominating transport mechanism in the POLO junctions investigated here.

  3. Cold air challenge and specific airway resistance in preschool children

    DEFF Research Database (Denmark)

    Nielsen, Kim Gjerum; Bisgaard, Hans

    2005-01-01

    prognosis in preschool children. Cold air challenge and plethysmographic measurement of specific airway resistance (sRaw) are feasible candidate methods for diagnosis, clinical monitoring and research during this critical period of lung growth and development. Methodology and practical aspects of cold air...... challenge and assessment of sRaw in preschool children are reviewed. Reference values are provided for sRaw and have allowed discrimination between health and respiratory disease, both in cross-sectional and longitudinal studies. Bronchial hyperresponsiveness can be determined with acceptable repeatability...

  4. Application Of Artificial Neural Networks In Modeling Of Manufactured Front Metallization Contact Resistance For Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Musztyfaga-Staszuk M.

    2015-09-01

    Full Text Available This paper presents the application of artificial neural networks for prediction contact resistance of front metallization for silicon solar cells. The influence of the obtained front electrode features on electrical properties of solar cells was estimated. The front electrode of photovoltaic cells was deposited using screen printing (SP method and next to manufactured by two methods: convectional (1. co-fired in an infrared belt furnace and unconventional (2. Selective Laser Sintering. Resistance of front electrodes solar cells was investigated using Transmission Line Model (TLM. Artificial neural networks were obtained with the use of Statistica Neural Network by Statsoft. Created artificial neural networks makes possible the easy modelling of contact resistance of manufactured front metallization and allows the better selection of production parameters. The following technological recommendations for the screen printing connected with co-firing and selective laser sintering technology such as optimal paste composition, morphology of the silicon substrate, co-firing temperature and the power and scanning speed of the laser beam to manufacture the front electrode of silicon solar cells were experimentally selected in order to obtain uniformly melted structure well adhered to substrate, of a small front electrode substrate joint resistance value. The prediction possibility of contact resistance of manufactured front metallization is valuable for manufacturers and constructors. It allows preserving the customers’ quality requirements and bringing also measurable financial advantages.

  5. Mesoscopic Oxide Double Layer as Electron Specific Contact for Highly Efficient and UV Stable Perovskite Photovoltaics.

    Science.gov (United States)

    Tavakoli, Mohammad Mahdi; Giordano, Fabrizio; Zakeeruddin, Shaik Mohammed; Grätzel, Michael

    2018-03-15

    The solar to electric power conversion efficiency (PCE) of perovskite solar cells (PSCs) has recently reached 22.7%, exceeding that of competing thin film photovoltaics and the market leader polycrystalline silicon. Further augmentation of the PCE toward the Shockley-Queisser limit of 33.5% warrants suppression of radiationless carrier recombination by judicious engineering of the interface between the light harvesting perovskite and the charge carrier extraction layers. Here, we introduce a mesoscopic oxide double layer as electron selective contact consisting of a scaffold of TiO 2 nanoparticles covered by a thin film of SnO 2 , either in amorphous (a-SnO 2 ), crystalline (c-SnO 2 ), or nanocrystalline (quantum dot) form (SnO 2 -NC). We find that the band gap of a-SnO 2 is larger than that of the crystalline (tetragonal) polymorph leading to a corresponding lift in its conduction band edge energy which aligns it perfectly with the conduction band edge of both the triple cation perovskite and the TiO 2 scaffold. This enables very fast electron extraction from the light perovskite, suppressing the notorious hysteresis in the current-voltage ( J-V) curves and retarding nonradiative charge carrier recombination. As a result, we gain a remarkable 170 mV in open circuit photovoltage ( V oc ) by replacing the crystalline SnO 2 by an amorphous phase. Because of the quantum size effect, the band gap of our SnO 2 -NC particles is larger than that of bulk SnO 2 causing their conduction band edge to shift also to a higher energy thereby increasing the V oc . However, for SnO 2 -NC there remains a barrier for electron injection into the TiO 2 scaffold decreasing the fill factor of the device and lowering the PCE. Introducing the a-SnO 2 coated mp-TiO 2 scaffold as electron extraction layer not only increases the V oc and PEC of the solar cells but also render them resistant to UV light which forebodes well for outdoor deployment of these new PSC architectures.

  6. Regulatory function of a novel population of mouse autoantigen-specific Foxp3 regulatory T cells depends on IFN-gamma, NO, and contact with target cells.

    Directory of Open Access Journals (Sweden)

    Cyndi Chen

    Full Text Available BACKGROUND: Both naturally arising Foxp3(+ and antigen-induced Foxp3(- regulatory T cells (Treg play a critical role in regulating immune responses, as well as in preventing autoimmune diseases and graft rejection. It is known that antigen-specific Treg are more potent than polyclonal Treg in suppressing pathogenic immune responses that cause autoimmunity and inflammation. However, difficulty in identifying and isolating a sufficient number of antigen-specific Treg has limited their use in research to elucidate the mechanisms underlying their regulatory function and their potential role in therapy. METHODOLOGY/PRINCIPAL FINDINGS: Using a novel class II MHC tetramer, we have isolated a population of CD4(+ Foxp3(- T cells specific for the autoantigen glutamic acid decarboxylase p286-300 peptide (NR286 T cells from diabetes-resistant non-obese resistant (NOR mice. These Foxp3(- NR286 T cells functioned as Treg that were able to suppress target T cell proliferation in vitro and inhibit type 1 diabetes in animals. Unexpected results from mechanistic studies in vitro showed that their regulatory function was dependent on not only IFN-gamma and nitric oxide, but also on cell contact with target cells. In addition, separating NR286 Treg from target T cells in transwell assays abolished both production of NO and suppression of target T cells, regardless of whether IFN-gamma was produced in cell cultures. Therefore, production of NO, not IFN-gamma, was cell contact dependent, suggesting that NO may function downstream of IFN-gamma in mediating regulatory function of NR286 Treg. CONCLUSIONS/SIGNIFICANCE: These studies identified a unique population of autoantigen-specific Foxp3(- Treg that can exert their regulatory function dependent on not only IFN-gamma and NO but also cell contact with target cells.

  7. Effect of Electrical Contact Resistance on Measurement of Thermal Conductivity and Wiedemann-Franz Law for Individual Metallic Nanowires.

    Science.gov (United States)

    Wang, Jianli; Wu, Zhizheng; Mao, Chengkun; Zhao, Yunfeng; Yang, Juekuan; Chen, Yunfei

    2018-03-20

    The electrical and thermal properties of metallic nanostructures have attracted considerable fundamental and technological interests. Recent studies confirmed a dramatic decrease in the electrical and thermal conductivities when the dimension is comparable or even smaller than the electron mean free path. However, the verification of the Wiedemann-Franz law in these nanostructures remains hotly debated. The Lorenz number obtained from the two-probe measurement is found to be much larger than that from the four-probe measurement. Here, we reported the electrical and thermal properties of the individual silver nanowires measured by the two-probe and four-probe configurations. The measured electrical contact resistance is found to be nearly temperature-independent, indicating a ballistic-dominant electronic transport at the contacts. When the effect of thermal contact resistance is diminished, the Lorenz number measured by the four-probe configuration is comparable to the Sommerfeld value, verifying that the Wiedemann-Franz law holds in the monocrystalline-like silver nanowire. Comparatively, the derived electrical conductivity becomes smaller and the thermal conductivity becomes larger in the two-probe measurement, confirming that the electrical contact resistance will introduce a large error. The present study experimentally demonstrates a reasonable explanation to the discouragingly broad span in the Lorenz number obtained from different metallic nanostructures.

  8. Relationships among the contact patch length and width, the tire deflection and the rolling resistance of a free-running wheel in a soil bin facility

    Energy Technology Data Exchange (ETDEWEB)

    Tomaraee, P.; Mardani, A.; Mohebbi, A.; Taghavifar, H.

    2015-07-01

    Qualitative and quantitative analysis of contact patch length-rolling resistance, contact patch width-rolling resistance and tire deflection-rolling resistance at different wheel load and inflation pressure levels is presented. The experiments were planned in a randomized block design and were conducted in the controlled conditions provided by a soil bin environment utilizing a well-equipped single wheel-tester of Urmia University, Iran. The image processing technique was used for determination of the contact patch length and contact patch width. Analysis of covariance was used to evaluate the correlations. The highest values of contact length and width and tire deflection occurred at the highest wheel load and lowest tire inflation pressure. Contact patch width is a polynomial (order 2) function of wheel load while there is a linear relationship between tire contact length and wheel load as well as between tire deflection and wheel load. Correlations were developed for the evaluation of contact patch length-rolling resistance, contact patch width-rolling resistance and tire deflection-rolling resistance. It is concluded that the variables studied have a significant effect on rolling resistance. (Author)

  9. Hazardous Air Pollutant Free Replacement for Specification A-A-1936A Contact Adhesive

    Science.gov (United States)

    2014-02-01

    compounds (VOCs) (5). The HAPs are petroleum distillate, n-hexane, and toluene. Also, this product contains cyclohexane (VOC), and acetone (HAP and...identified various commercially available, environmentally friendly adhesives with promising characteristics through a survey of products from adhesive...DAP Products Inc. 3M Scotch-Weld Neoprene Contact Adhesive 10 (baseline) is a multipurpose brushable contact adhesive, which may be used to bond

  10. Evaluation of contact resistance between carbon fiber/epoxy composite laminate and printed silver electrode for damage monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Eun Beom; Kim, Hak Sung [Dept. of Mechanical Convergence Engineering, Hanyang University, Seoul (Korea, Republic of); Takahashi, Kosuke [Dept. of Mechanical Sciences and Engineering, Tokyo Institute of Technology, Tokyo (Korea, Republic of)

    2014-10-15

    An addressable conducting network (ACN) makes it possible to monitor the condition of a structure using the electrical resistance between electrodes on the surface of a carbon fiber reinforced plastics (CFRP) structure. To improve the damage detection reliability of the ACN, the contact resistances between the electrodes and CFRP laminates needs to be minimized. In this study, silver nanoparticle electrodes were fabricated via printed electronics techniques on a CFRP composite. The contact resistance between the silver electrodes and CFRP were measured with respect to various fabrication conditions such as the sintering temperature of the silver nano-ink and the surface roughness of the CFRP laminates. The interfaces between the silver electrode and carbon fibers were observed using a scanning electron microscope (SEM). Based on this study, it was found that the lowest contact resistance of 0.3664Ω could be achieved when the sintering temperature of the silver nano-ink and surface roughness were 120 degree C and 0.230 a, respectively.

  11. Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

    International Nuclear Information System (INIS)

    Vecchiola, Aymeric; Chrétien, Pascal; Schneegans, Olivier; Mencaraglia, Denis; Houzé, Frédéric; Delprat, Sophie; Bouzehouane, Karim; Seneor, Pierre; Mattana, Richard; Tatay, Sergio; Geffroy, Bernard

    2016-01-01

    An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.

  12. Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

    Energy Technology Data Exchange (ETDEWEB)

    Vecchiola, Aymeric [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Concept Scientific Instruments, ZA de Courtaboeuf, 2 rue de la Terre de Feu, 91940 Les Ulis (France); Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Chrétien, Pascal; Schneegans, Olivier; Mencaraglia, Denis; Houzé, Frédéric, E-mail: frederic.houze@geeps.centralesupelec.fr [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Delprat, Sophie [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); UPMC, Université Paris 06, 4 place Jussieu, 75005 Paris (France); Bouzehouane, Karim; Seneor, Pierre; Mattana, Richard [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Tatay, Sergio [Molecular Science Institute, University of Valencia, 46980 Paterna (Spain); Geffroy, Bernard [Lab. Physique des Interfaces et Couches minces (PICM), UMR 7647 CNRS-École polytechnique, 91128 Palaiseau (France); Lab. d' Innovation en Chimie des Surfaces et Nanosciences (LICSEN), NIMBE UMR 3685 CNRS-CEA Saclay, 91191 Gif-sur-Yvette (France); and others

    2016-06-13

    An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.

  13. Contact networks structured by sex underpin sex-specific epidemiology of infection.

    Science.gov (United States)

    Silk, Matthew J; Weber, Nicola L; Steward, Lucy C; Hodgson, David J; Boots, Mike; Croft, Darren P; Delahay, Richard J; McDonald, Robbie A

    2018-02-01

    Contact networks are fundamental to the transmission of infection and host sex often affects the acquisition and progression of infection. However, the epidemiological impacts of sex-related variation in animal contact networks have rarely been investigated. We test the hypothesis that sex-biases in infection are related to variation in multilayer contact networks structured by sex in a population of European badgers Meles meles naturally infected with Mycobacterium bovis. Our key results are that male-male and between-sex networks are structured at broader spatial scales than female-female networks and that in male-male and between-sex contact networks, but not female-female networks, there is a significant relationship between infection and contacts with individuals in other groups. These sex differences in social behaviour may underpin male-biased acquisition of infection and may result in males being responsible for more between-group transmission. This highlights the importance of sex-related variation in host behaviour when managing animal diseases. © 2017 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.

  14. Contact allergy to the 26 specific fragrance ingredients to be declared on cosmetic products in accordance with the EU cosmetics directive

    DEFF Research Database (Denmark)

    Heisterberg, Maria V; Menné, Torkil; Johansen, Jeanne D

    2011-01-01

    Background. Fragrance ingredients are a frequent cause of allergic contact dermatitis. The EU Cosmetics Directive states that 26 specific fragrance ingredients, known to cause allergic contact dermatitis, must be declared on the ingredient lists of cosmetic products. Objectives. To investigate...

  15. Specific emotions as mediators of the effect of intergroup contact on prejudice: findings across multiple participant and target groups.

    Science.gov (United States)

    Seger, Charles R; Banerji, Ishani; Park, Sang Hee; Smith, Eliot R; Mackie, Diane M

    2017-08-01

    Emotions are increasingly being recognised as important aspects of prejudice and intergroup behaviour. Specifically, emotional mediators play a key role in the process by which intergroup contact reduces prejudice towards outgroups. However, which particular emotions are most important for prejudice reduction, as well as the consistency and generality of emotion-prejudice relations across different in-group-out-group relations, remain uncertain. To address these issues, in Study 1 we examined six distinct positive and negative emotions as mediators of the contact-prejudice relations using representative samples of U.S. White, Black, and Asian American respondents (N = 639). Admiration and anger (but not other emotions) were significant mediators of the effects of previous contact on prejudice, consistently across different perceiver and target ethnic groups. Study 2 examined the same relations with student participants and gay men as the out-group. Admiration and disgust mediated the effect of past contact on attitude. The findings confirm that not only negative emotions (anger or disgust, based on the specific types of threat perceived to be posed by an out-group), but also positive, status- and esteem-related emotions (admiration) mediate effects of contact on prejudice, robustly across several different respondent and target groups.

  16. Yield of facility-based verbal screening amongst household contacts of patients with multi-drug resistant tuberculosis in Pakistan

    Directory of Open Access Journals (Sweden)

    Ejaz Qadeer

    2017-05-01

    Full Text Available Background: Household contacts of multidrug-resistant tuberculosis (MDR-TB patients are at a high risk of getting infected with TB/MDR-TB, therefore symptomatic or vulnerable individuals should be screened and treated early. Methods: A cross-sectional study was conducted among household contacts of MDR-TB patients in three high-burden TB sites in Pakistan from July 2013 to June 2014. MDR-TB index patients were asked to provide a list of all members of their household and were asked whether any of them had TB symptoms such as productive cough, fever, weight loss and night sweat (“facility-based verbal screening”. Symptomatic contacts were defined as presumptive TB cases and were invited for investigations at the facility. Those who did not come were paid a home-visit. Confirmed TB/MDR-TB patients were registered in the nearest treatment facility. Results: Of 209 MDR-TB index patients, 1467 household contacts were identified and screened, 95 of them children < 5 years. Of these 172 (12% were symptomatic. Most common symptoms were cough 157 (91% and fever 107 (62%. 58 (34% presumptive TB contacts were not investigated. Of total contacts, 56 (3.8% were diagnosed with TB, among them 54(96% with MDR-TB and 2(4% with drug-susceptible-TB. The number needed to screen (NNS to identify a new MDR-TB case among adult household contacts was 27 and among presumptive adult and pediatric TB contacts was three. All 56 confirmed patients were registered for treatment. Conclusion: Screening household contacts of MDR-TB index cases may be considered a feasible and high yield option, in high-burden, low-resource settings within Pakistan. The number of presumptive TB contacts required to screen to identify a new MDR-TB case was unusually low, indicating an effective strategy that could easily be scaled-up. The screening and management of vulnerable adults and children living with patients having TB of any form is a major priority in the combined efforts

  17. Screening and contact precautions – A survey on infection control measures for multidrug-resistant bacteria in German university hospitals

    Directory of Open Access Journals (Sweden)

    Lena M. Biehl

    2017-04-01

    Full Text Available Abstract To assess the scope of infection control measures for multidrug-resistant bacteria in high-risk settings, a survey among university hospitals was conducted. Fourteen professionals from 8 sites participated. Reported policies varied largely with respect to the types of wards conducting screening, sample types used for screening and implementation of contact precautions. This variability among sites highlights the need for an evidence-based consensus of current infection control policies.

  18. Contact transmission of influenza virus between ferrets imposes a looser bottleneck than respiratory droplet transmission allowing propagation of antiviral resistance

    Science.gov (United States)

    Frise, Rebecca; Bradley, Konrad; van Doremalen, Neeltje; Galiano, Monica; Elderfield, Ruth A.; Stilwell, Peter; Ashcroft, Jonathan W.; Fernandez-Alonso, Mirian; Miah, Shahjahan; Lackenby, Angie; Roberts, Kim L.; Donnelly, Christl A.; Barclay, Wendy S.

    2016-01-01

    Influenza viruses cause annual seasonal epidemics and occasional pandemics. It is important to elucidate the stringency of bottlenecks during transmission to shed light on mechanisms that underlie the evolution and propagation of antigenic drift, host range switching or drug resistance. The virus spreads between people by different routes, including through the air in droplets and aerosols, and by direct contact. By housing ferrets under different conditions, it is possible to mimic various routes of transmission. Here, we inoculated donor animals with a mixture of two viruses whose genomes differed by one or two reverse engineered synonymous mutations, and measured the transmission of the mixture to exposed sentinel animals. Transmission through the air imposed a tight bottleneck since most recipient animals became infected by only one virus. In contrast, a direct contact transmission chain propagated a mixture of viruses suggesting the dose transferred by this route was higher. From animals with a mixed infection of viruses that were resistant and sensitive to the antiviral drug oseltamivir, resistance was propagated through contact transmission but not by air. These data imply that transmission events with a looser bottleneck can propagate minority variants and may be an important route for influenza evolution. PMID:27430528

  19. Subchronic sleep restriction causes tissue-specific insulin resistance.

    Science.gov (United States)

    Rao, Madhu N; Neylan, Thomas C; Grunfeld, Carl; Mulligan, Kathleen; Schambelan, Morris; Schwarz, Jean-Marc

    2015-04-01

    Short sleep duration is associated with an increased risk of type 2 diabetes. Subchronic sleep restriction (SR) causes insulin resistance, but the mechanisms and roles of specific tissues are unclear. The purpose of this article was to determine whether subchronic SR altered (1) hepatic insulin sensitivity, (2) peripheral insulin sensitivity, and (3) substrate utilization. This was a randomized crossover study in which 14 subjects underwent 2 admissions separated by a washout period. Each admission had 2 acclimatization nights followed by 5 nights of either SR (4 hours time in bed) or normal sleep (8 hours time in bed). MAIN OUTCOME MEASURE/METHODS: Insulin sensitivity (measured by hyperinsulinemic-euglycemic clamp) and hepatic insulin sensitivity (measured by stable isotope techniques) were measured. In addition, we assayed stress hormone (24-hour urine free cortisol, metanephrine, and normetanephrine), nonesterified fatty acid (NEFA), and β-hydroxybutyrate (β-OH butyrate) levels. Resting energy expenditure (REE) and respiratory quotient (RQ) were measured by indirect calorimetry. Compared to normal sleep, whole-body insulin sensitivity decreased by 25% (P = .008) with SR and peripheral insulin sensitivity decreased by 29% (P = .003). Whereas hepatic insulin sensitivity (endogenous glucose production) did not change significantly, percent gluconeogenesis increased (P = .03). Stress hormones increased modestly (cortisol by 21%, P = .04; metanephrine by 8%, P = .014; normetanephrine by 18%, P = .002). Fasting NEFA and β-OH butyrate levels increased substantially (62% and 55%, respectively). REE did not change (P = 0.98), but RQ decreased (0.81 ± .02 vs 0.75 ± 0.02, P = .045). Subchronic SR causes unique metabolic disturbances characterized by peripheral, but not hepatic, insulin resistance; this was associated with a robust increase in fasting NEFA levels (indicative of increased lipolysis), decreased RQ, and increased β-OH butyrate levels (indicative of whole

  20. On the non-proportionality between wheel/rail contact forces and speed during wheelset passage over specific welds

    Science.gov (United States)

    Correa, Nekane; Vadillo, Ernesto G.; Santamaria, Javier; Blanco-Lorenzo, Julio

    2018-01-01

    This study investigates the influence on the wheel-rail contact forces of the running speed and the shape and position of weld defects along the track. For this purpose, a vertical dynamic model in the space domain is used. The model is obtained from the transformation between the domains of frequency and space using a Rational Fraction Polynomials (RFP) method, which is modified with multiobjective genetic algorithms in order to improve the fitting of track receptance and to assist integration during simulations. This produces a precise model with short calculation times, which is essential to this study. The wheel-rail contact is modelled using a non-linear Hertz spring. The contact forces are studied for several types of characteristic welds. The way in which forces vary as a function of weld position and running speed is studied for each type of weld. This paper studies some of the factors that affect the maximum forces when the vehicle moves over a rail weld, such as weld geometry, parametric excitation and contact stiffness. It is found that the maximum force in the wheel-rail contact when the vehicle moves over a weld is not always proportional to the running speed. The paper explains why it is not proportional in specific welds.

  1. In the eye of the beholder: eye contact increases resistance to persuasion.

    Science.gov (United States)

    Chen, Frances S; Minson, Julia A; Schöne, Maren; Heinrichs, Markus

    2013-11-01

    Popular belief holds that eye contact increases the success of persuasive communication, and prior research suggests that speakers who direct their gaze more toward their listeners are perceived as more persuasive. In contrast, we demonstrate that more eye contact between the listener and speaker during persuasive communication predicts less attitude change in the direction advocated. In Study 1, participants freely watched videos of speakers expressing various views on controversial sociopolitical issues. Greater direct gaze at the speaker's eyes was associated with less attitude change in the direction advocated by the speaker. In Study 2, we instructed participants to look at either the eyes or the mouths of speakers presenting arguments counter to participants' own attitudes. Intentionally maintaining direct eye contact led to less persuasion than did gazing at the mouth. These findings suggest that efforts at increasing eye contact may be counterproductive across a variety of persuasion contexts.

  2. Specific airway resistance, interrupter resistance, and respiratory impedance in healthy children aged 2-7 years

    DEFF Research Database (Denmark)

    Klug, B; Bisgaard, H

    1998-01-01

    resistance (sRaw) by a modified procedure method in the whole body plethysmograph. Measurements were attempted in 151 children and were successfully obtained in 121 children with a mean (SD) age of 5.3 (1.5) years; no measurements were possible in 30 children (mean age 3 (0.9) years). The repeatability...... with age, height, and weight was found for Rint, Zrs, and Rrs5. Xrs5 was positively correlated to age and body size. The mean values of Rint, Rrs5, Xrs5, and Zrs in children younger and older than 5 years were 1.04, 1.38, -0.5, and 1.48 kPa x L(-1) x s and 0.9, 1.18, -0.37, and 1.23 kPa x L(-1) x s......We report data on respiratory function in healthy children aged 2-7 years in whom we measured respiratory resistance by the interrupter technique (Rint); total respiratory impedance (Zrs), respiratory resistance (Rrs), and reactance (Xrs) by the impulse oscillation technique; and specific airway...

  3. Investigation on the variation of channel resistance and contact resistance of SiZnSnO semiconductor depending on Si contents using transmission line method

    Science.gov (United States)

    Lee, Byeong Hyeon; Han, Sangmin; Lee, Sang Yeol

    2018-01-01

    Amorphous silicon-zinc-tin-oxide (a-SZTO) thin film transistors (TFTs) have been fabricated depending on the silicon ratio in channel layers. The a-SZTO TFT exhibited high electrical properties, such as high mobility of 23 cm2 V-1 s-1, subthreshold swing of 0.74 V/decade and ION/OFF of 2.8 × 108, despite of the addition of Si suppressor. The physical mechanism on the change of the sheet resistance and the contact resistance in a-SZTO TFT has been investigated and proposed closely related with the Si ratio. Both resistances were increased as increasing Si ratio, which clearly indicated that the role of Si is a carrier suppressor directly leading to the increase of channel and contact resistances. To explain the role of Si as a carrier suppressor, the conduction band offset mechanism has been also proposed depending on the change of carrier concentration in channel layer and at the interface between electrode and channel layer. 2007.01-2011.12 Senior Researcher at korea institute of science and technology (KOREA). 2008.01-2011.12 Professor at University of Science and Technology (KOREA). 1995.01-2007.12 Professor at Yonsei University (KOREA). 2002.01-2003.12 Inviting Researcher at Los Alamos National Lab (USA). 1993.01-1995.12 Senior Researcher at Electronics and Telecommunications Research Institute (KOREA). 1992.01-1993.01 Research Associate at State University of New York at Buffalo (USA).

  4. Effect of specific resistance training on musculoskeletal pain symptoms

    DEFF Research Database (Denmark)

    Pedersen, Mogens Theisen; Andersen, Lars Louis; Jørgensen, Marie Birk

    2013-01-01

    ABSTRACT: Pedersen, MT, Andersen, LL, Jørgensen, MB, Søgaard, K, and Sjøgaard, G. Effect of specific resistance training on musculoskeletal pain symptoms: Dose-response relationship. J Strength Cond Res 27(1): 229-235, 2013-The purpose of this study was to investigate the dose-response of strength...... training for relieving musculoskeletal pain in female office workers. The relation between the dose of training in terms of total training volume (sets × repetitions × load reported in training diaries) during a 16-week strength training program and changes in pain (calculated as pain index, 0-100%, from...... index in SRT and APE decreased significantly from baseline to follow-up (-25%/-22%) compared with changes in REF (-15%). In the dose-response analysis within the SRT group (n = 125), the total volume of training (mean 18.056 kg, SD = 13.798) was negatively correlated with changes in pain index (ß = -0...

  5. Evaluation of biofilm-specific antimicrobial resistance genes in Pseudomonas aeruginosa isolates in Farabi Hospital.

    Science.gov (United States)

    Saffari, Mahmood; Karami, Shabnam; Firoozeh, Farzaneh; Sehat, Mojtaba

    2017-07-01

    Biofilm produced from Pseudomonas aeruginosa is the cause of infection induced by contact lenses, trauma and post-surgery infection. The aim of this study was to evaluate biofilm formation and the presence of the genes ndvB and tssC1 in ocular infection isolates of P. aeruginosa. A total of 92 P. aeruginosa strains were collected from patients with ocular infection referred to Farabi Hospital between March 2014 and July 2015. Antibiotic susceptibility patterns were evaluated by the agar disc-diffusion method according to CLSI guidelines. PCR assays were used to detect ndvB and tssC1, genes associated with resistance in biofilm-producing P. aeruginosa isolates. Biofilm formation ability was examined by crystal violet microtitre plate assay. During the period of study, 92 P. aeruginosa were isolated from ocular infections including keratitis (n=84) and endophthalmitis (n=8). The highest resistance rates were seen against colistin (57.6 %) and gentamicin (50 %) and the lowest resistance rates were seen against imipenem (3.3 %), aztreonam (4.3 %), piperacillin-tazobactam (4.3 %), ceftazidime (4.3 %) and ciprofloxacin (5.4 %). Biofilm production ability was found in 100 % of the isolates. PCR assays showed that of the 92 P. aeruginosa isolates, 96.7 and 90.2 % harboured the genes ndvB and tssC1, respectively. Our results showed a considerable ability of biofilm production, as well as the occurrence of biofilm-specific antimicrobial resistance genes (ndvB and tssC1), in P. aeruginosa isolates from ocular infections in Farabi Hospital.

  6. The Variations of Thermal Contact Resistance and Heat Transfer Rate of the AlN Film Compositing with PCM

    Directory of Open Access Journals (Sweden)

    Huann-Ming Chou

    2015-01-01

    Full Text Available The electrical industries have been fast developing over the past decades. Moreover, the trend of microelements and packed division multiplex is obviously for the electrical industry. Hence, the high heat dissipative and the electrical insulating device have been popular and necessary. The thermal conduct coefficient of aluminum nitride (i.e., AlN is many times larger than the other materials. Moreover, the green technology of composite with phase change materials (i.e., PCMs is worked as a constant temperature cooler. Therefore, PCMs have been used frequently for saving energy and the green environment. Based on the above statements, it does show great potential in heat dissipative for the AlN film compositing with PCM. Therefore, this paper is focused on the research of thermal contact resistance and heat transfer between the AlN/PCM pairs. According to the experimental results, the heat transfer decreases and the thermal contact resistance increases under the melting process of PCM. However, the suitable parameters such as contact pressures can be used to improve the above defects.

  7. Subject-specific analysis of joint contact mechanics: application to the study of osteoarthritis and surgical planning.

    Science.gov (United States)

    Henak, Corinne R; Anderson, Andrew E; Weiss, Jeffrey A

    2013-02-01

    Advances in computational mechanics, constitutive modeling, and techniques for subject-specific modeling have opened the door to patient-specific simulation of the relationships between joint mechanics and osteoarthritis (OA), as well as patient-specific preoperative planning. This article reviews the application of computational biomechanics to the simulation of joint contact mechanics as relevant to the study of OA. This review begins with background regarding OA and the mechanical causes of OA in the context of simulations of joint mechanics. The broad range of technical considerations in creating validated subject-specific whole joint models is discussed. The types of computational models available for the study of joint mechanics are reviewed. The types of constitutive models that are available for articular cartilage are reviewed, with special attention to choosing an appropriate constitutive model for the application at hand. Issues related to model generation are discussed, including acquisition of model geometry from volumetric image data and specific considerations for acquisition of computed tomography and magnetic resonance imaging data. Approaches to model validation are reviewed. The areas of parametric analysis, factorial design, and probabilistic analysis are reviewed in the context of simulations of joint contact mechanics. Following the review of technical considerations, the article details insights that have been obtained from computational models of joint mechanics for normal joints; patient populations; the study of specific aspects of joint mechanics relevant to OA, such as congruency and instability; and preoperative planning. Finally, future directions for research and application are summarized.

  8. Select small core structure carbamates exhibit high contact toxicity to "carbamate-resistant" strain malaria mosquitoes, Anopheles gambiae (Akron).

    Science.gov (United States)

    Wong, Dawn M; Li, Jianyong; Chen, Qiao-Hong; Han, Qian; Mutunga, James M; Wysinski, Ania; Anderson, Troy D; Ding, Haizhen; Carpenetti, Tiffany L; Verma, Astha; Islam, Rafique; Paulson, Sally L; Lam, Polo C-H; Totrov, Maxim; Bloomquist, Jeffrey R; Carlier, Paul R

    2012-01-01

    Acetylcholinesterase (AChE) is a proven target for control of the malaria mosquito (Anopheles gambiae). Unfortunately, a single amino acid mutation (G119S) in An. gambiae AChE-1 (AgAChE) confers resistance to the AChE inhibitors currently approved by the World Health Organization for indoor residual spraying. In this report, we describe several carbamate inhibitors that potently inhibit G119S AgAChE and that are contact-toxic to carbamate-resistant An. gambiae. PCR-RFLP analysis was used to confirm that carbamate-susceptible G3 and carbamate-resistant Akron strains of An. gambiae carry wild-type (WT) and G119S AChE, respectively. G119S AgAChE was expressed and purified for the first time, and was shown to have only 3% of the turnover number (k(cat)) of the WT enzyme. Twelve carbamates were then assayed for inhibition of these enzymes. High resistance ratios (>2,500-fold) were observed for carbamates bearing a benzene ring core, consistent with the carbamate-resistant phenotype of the G119S enzyme. Interestingly, resistance ratios for two oxime methylcarbamates, and for five pyrazol-4-yl methylcarbamates were found to be much lower (4- to 65-fold). The toxicities of these carbamates to live G3 and Akron strain An. gambiae were determined. As expected from the enzyme resistance ratios, carbamates bearing a benzene ring core showed low toxicity to Akron strain An. gambiae (LC(50)>5,000 μg/mL). However, one oxime methylcarbamate (aldicarb) and five pyrazol-4-yl methylcarbamates (4a-e) showed good to excellent toxicity to the Akron strain (LC(50) = 32-650 μg/mL). These results suggest that appropriately functionalized "small-core" carbamates could function as a resistance-breaking anticholinesterase insecticides against the malaria mosquito.

  9. Systematic drug screening reveals specific vulnerabilities and co-resistance patterns in endocrine-resistant breast cancer

    International Nuclear Information System (INIS)

    Kangaspeska, Sara; Hultsch, Susanne; Jaiswal, Alok; Edgren, Henrik; Mpindi, John-Patrick; Eldfors, Samuli; Brück, Oscar; Aittokallio, Tero; Kallioniemi, Olli

    2016-01-01

    The estrogen receptor (ER) inhibitor tamoxifen reduces breast cancer mortality by 31 % and has served as the standard treatment for ER-positive breast cancers for decades. However, 50 % of advanced ER-positive cancers display de novo resistance to tamoxifen, and acquired resistance evolves in 40 % of patients who initially respond. Mechanisms underlying resistance development remain poorly understood and new therapeutic opportunities are urgently needed. Here, we report the generation and characterization of seven tamoxifen-resistant breast cancer cell lines from four parental strains. Using high throughput drug sensitivity and resistance testing (DSRT) with 279 approved and investigational oncology drugs, exome-sequencing and network analysis, we for the first time, systematically determine the drug response profiles specific to tamoxifen resistance. We discovered emerging vulnerabilities towards specific drugs, such as ERK1/2-, proteasome- and BCL-family inhibitors as the cells became tamoxifen-resistant. Co-resistance to other drugs such as the survivin inhibitor YM155 and the chemotherapeutic agent paclitaxel also occurred. This study indicates that multiple molecular mechanisms dictate endocrine resistance, resulting in unexpected vulnerabilities to initially ineffective drugs, as well as in emerging co-resistances. Thus, combatting drug-resistant tumors will require patient-tailored strategies in order to identify new drug vulnerabilities, and to understand the associated co-resistance patterns. The online version of this article (doi:10.1186/s12885-016-2452-5) contains supplementary material, which is available to authorized users

  10. Electrical contacting techniques for high Tc superconductor applications

    International Nuclear Information System (INIS)

    Tzeng, Y.; Belser, M.

    1988-01-01

    Three methods for making low resistivity electrical contacts to high Tc superconductors have been studied. This includes vacuum deposition of silver thin films, welding of silver to HTSC, and painting or printing of silver contacts to HTSC. Specific contact resistance lower than 1 . E-8 Ohm-cm2 can routinely be achieved for both electronic and power applications. Oxygen annealing is found to improve the contact resistance significantly. Both the contact fabrication processes and the electrical properties of these contacts will be discussed

  11. Effect of Contact Temperature Rise During Sliding on the Wear Resistance of TiNi Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    S.K. Roy Chowdhury

    2013-03-01

    Full Text Available The high wear resistance of TiNi shape memory alloys has generally been attributed to its pseudoelastic nature. In the present work the hardening effect due to its phase transformation from martensite to austenite due to frictional heating during sliding has been considered. Based on existing constitutive models that represent the experimental results of TiNi shape memory alloys a theoretical model of the dependence of wear-resistance on the contact temperature rise has been developed. The analysis was further extended to include the operating and surface roughness parameters. The model essentially indicates that for these alloys wear decreases with the rise in contact temperature over a wide range of load, speed and surface roughness combination during sliding. This means that the wear resistance of these alloys results from the very cause that is normally responsible for the increased wear and seizure of common engineering materials. Preliminary wear tests were carried out with TiNi alloys at varying ambient temperature and varying load-speed combinations and the results agree well with the theoretical predictions.

  12. The effect of boron implantation on the corrosion behaviour, microhardness and contact resistance of copper and silver surfaces

    International Nuclear Information System (INIS)

    Henriksen, O.; Johnson, E.; Johansen, A.; Sarholt-Kristensen, L.

    1986-01-01

    In order to investigate the influence of boron implantation on the corrosion resistance of electrical contacts, a number of pure copper, pure silver and copper edge connector samples have been implanted with boron (40 keV) to fluences of 5.10 20 m -2 and 2.10 21 m -2 . Atmospheric corrosion tests of the implanted species were conducted using the following exposures: H 2 S (12.5 ppm, 4 days), SO 2 (25 ppm, 21 days), saltfog (5% NaCl, 1 day), moist air (93% RH, 56 days), and hot/dry air (70 C, 56 days). The boron implantations lead to a significant reduction in the sulphidation rate of copper and silver. The corrosive film formed during exposure in H 2 S and SO 2 atmospheres is confined to pitted regions on the implanted areas, while a thick and relatively uniform film formation is observed on the unimplanted samples. The corrosion resistance of copper and silver in saltfog atmosphere is somewhat improved by boron implantation, whilst the results from exposures to moist air or hot/dry air are inconclusive. The improved corrosion behaviour is accompanied by an increase in the contact resistance and in the microhardness of the implanted samples. (orig.)

  13. Four-terminal resistance of an interacting quantum wire with weakly invasive contacts

    Science.gov (United States)

    Aita, Hugo; Arrachea, Liliana; Naón, Carlos

    2011-11-01

    We analyze the behavior of the four-terminal resistance, relative to the two-terminal resistance of an interacting quantum wire with an impurity, taking into account the invasiveness of the voltage probes. We consider a one-dimensional Luttinger model of spinless fermions for the wire. We treat the coupling to the voltage probes perturbatively, within the framework of non-equilibrium Green function techniques. Our investigation unveils the combined effect of impurities, electron-electron interactions and invasiveness of the probes on the possible occurrence of negative resistance.

  14. Low resistivity molybdenum thin film towards the back contact of dye ...

    Indian Academy of Sciences (India)

    Abstract. This paper reports the optimization of the molybdenum thin film electrode as the back contact of dye-sensitized solar cell (DSSC). The molybdenum thin film was grown on the glass substrate by direct current sputtering techniques of which the sputtering power was 150Wat 18 sccm flow rate of Ar. At such sputtering ...

  15. Low resistivity molybdenum thin film towards the back contact of dye ...

    Indian Academy of Sciences (India)

    Abstract. This paper reports the optimization of the molybdenum thin film electrode as the back contact of dye-sensitized solar cell (DSSC). The molybdenum thin film was grown on the glass substrate by direct current sput- tering techniques of which the sputtering power was 150 W at 18 sccm flow rate of Ar. At such ...

  16. Contact Resistance and Stability Analysis of Oxide-Based Thin Film Transistors

    Science.gov (United States)

    2006-09-19

    SnO2 [9], as well as the single-crystalline, quaternary compound IGZO [5] have also been demonstrated as channel materials. ITO, ZnO, ZIO, and IGO...that the material properties of ITO vary greatly depending on deposition parameters: method of deposition, oxygen partial pressure, source material...the resist to the surface of the substrate and drives out excess solvent from the photoresist. The image from a mask is then transferred to the resist

  17. A new contact electric resistance technique for in-situ measurement of the electric resistance of surface films on metals in electrolytes at high temperatures and pressures

    International Nuclear Information System (INIS)

    Saario, T.; Marichev, V.A.

    1993-01-01

    Surface films play a major role in corrosion assisted cracking. A new Contact Electric Resistance (CER) method has been recently developed for in situ measurement of the electric resistance of surface films. The method has been upgraded for high temperature high pressure application. The technique can be used for any electrically conductive material in any environment including liquid, gas or vacuum. The technique has been used to determine in situ the electric resistance of films on metals during adsorption of water and anions, formation and destruction of oxides and hydrides, electroplating of metals and to study the electric resistance of films on semiconductors. The resolution of the CER technique is 10 -9 Ω, which corresponds to about 0.03 monolayers of deposited copper during electrochemical deposition Cu/Cu 2+ . Electric resistance data can be measured with a frequency of the order of one hertz, which enables one to follow in situ the kinetics of surface film related processes. The kinetics of these processes and their dependence on the environment, temperature, pH and electrochemical potential can be investigated

  18. Interstrand contact resistance and AC loss of a 48-strands Nb3Sn CIC conductor with a Cr/Cr-oxide coating

    NARCIS (Netherlands)

    Nijhuis, Arend; ten Kate, Herman H.J.; Pantsyrny, Victor; Shikov, Alexander K.

    2000-01-01

    The interstrand contact resistance (Rc) between crossing strands in Cable-In-Conduit Conductors (CICC's) determines the coupling loss and the stability against local disturbances. The surface oxidation, surface roughness and micro-scale sliding of the contact surfaces are key parameters in the Rc.

  19. Region specific patella tendon hypertrophy in humans following resistance training

    DEFF Research Database (Denmark)

    Kongsgaard, M.; Reitelseder, S; Pedersen, T.G.

    2007-01-01

    AIM: To examine if cross-sectional area (CSA) differs along the length of the human patellar tendon (PT), and if there is PT hypertrophy in response to resistance training. METHODS: Twelve healthy young men underwent baseline and post-training assessments. Maximal isometric knee extension strength......, subjects performed 12 weeks of heavy resistance knee extension training with one leg (Heavy-leg), and light resistance knee extension training with the other leg (Light-leg). RESULTS: The MVC increased for heavy-leg (15 +/- 4%, P .... CONCLUSIONS: To our knowledge, this study is the first to report tendon hypertrophy following resistance training. Further, the data show that the human PT CSA varies along the length of the tendon....

  20. Sharing specific "We" autobiographical memories in close relationships: the role of contact frequency.

    Science.gov (United States)

    Beike, Denise R; Cole, Holly E; Merrick, Carmen R

    2017-11-01

    Sharing memories in conversations with close others is posited to be part of the social function of autobiographical memory. The present research focused on the sharing of a particular type of memory: Specific memories about one-time co-experienced events, which we termed Specific We memories. Two studies with 595 total participants examined the factors that lead to and/or are influenced by the sharing of Specific We memories. In Study 1, participants reported on their most recent conversation. Specific We memories were reportedly discussed most often in conversations with others who were close and with whom the participant had frequent communication. In Study 2, participants were randomly assigned either to increase or to simply record the frequency of communication with a close other (parent). Increases in the frequency of reported sharing of Specific We memories as well as closeness to the parent resulted. Mediation analyses of both studies revealed causal relationships among reported sharing of Specific We memories and closeness. We discuss the relevance of these results for understanding the social function of autobiographical memory.

  1. Fabrication of four-point biped robot foot module based on contact-resistance force sensor and its evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyun Joon; Kim, Jong Ho; Kim, Dong Ki [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Kwon, Young Ha [Kyung Hee University, Yongin (Korea, Republic of)

    2011-02-15

    This paper presents the design of robot foot module of four-point biped walking robot and its fabrication. The foot module has four sensor units based on contact-resistance force sensor. The thin-film-type force sensor is fabricated by coating resistive ink on thin polyimide film using silk screening technique. The simple structure is devised and fabricated to assemble the thin force sensor rigidly. The unit force sensor module is evaluated by the calibration setup to obtain the characteristics of repeatability and hysteresis. The sensor module presents hysteresis error of about 5% and repeatability error of about 0.37%. The calculated zero moment point (ZMP) of the foot module is also compared with the measured position using static load of 50 N. The maximum location error of ZMP is less than 10%. The robot foot module shows the possibility of applying it to humanoid walking.

  2. Fabrication of four-point biped robot foot module based on contact-resistance force sensor and its evaluation

    International Nuclear Information System (INIS)

    Kwon, Hyun Joon; Kim, Jong Ho; Kim, Dong Ki; Kwon, Young Ha

    2011-01-01

    This paper presents the design of robot foot module of four-point biped walking robot and its fabrication. The foot module has four sensor units based on contact-resistance force sensor. The thin-film-type force sensor is fabricated by coating resistive ink on thin polyimide film using silk screening technique. The simple structure is devised and fabricated to assemble the thin force sensor rigidly. The unit force sensor module is evaluated by the calibration setup to obtain the characteristics of repeatability and hysteresis. The sensor module presents hysteresis error of about 5% and repeatability error of about 0.37%. The calculated zero moment point (ZMP) of the foot module is also compared with the measured position using static load of 50 N. The maximum location error of ZMP is less than 10%. The robot foot module shows the possibility of applying it to humanoid walking

  3. Influence of strand surface condition on interstrand contact resistance and coupling loss in NbTi-wound Rutherford cables

    CERN Document Server

    Sumption, M D; Scanlan, R M; Nijhuis, A; ten Kate, H H J; Kim, S W; Wake, M; Shintomi, T

    1999-01-01

    Presented in this work are the results of directly measured and AC- loss-derived interstrand contact resistance (ICR) measurements performed magnetically or resistively on bare-Cu and coated-strand pairs, calorimetrically on $9 11-strand Rutherford cables wound with strands that had been coated with various metallic and insulating layers, and calorimetrically and magnetically on 28-strand Rutherford cables (LHC-type) wound with bare-Cu-, Ni-, and $9 stabrite-plated strands. Comparisons are made of the effects of various conditions of heat treatment, HT (time and temperature), and pressure (applied during HT and then either maintained or re-applied during measurement). The $9 resulting ICRs are compared and interpreted in terms of the oxide layer on the strand coating and its response to curing conditions. (66 refs).

  4. Determination and Application of Comprehensive Specific Frictional Resistance in Heating Engineering

    Directory of Open Access Journals (Sweden)

    Yanan Tian

    2018-01-01

    Full Text Available In this study, we analyze the deficiencies of specific frictional resistance in heating engineering. Based on economic specific frictional resistance, we put forward the concept of comprehensive specific frictional resistance, which considers the multiple factors of technology, economy, regulation modes, pipe segment differences, and medium pressure. Then, we establish a mathematical model of a heating network across its lifespan in order to develop a method for determining the comprehensive specific frictional resistance. Relevant conclusions can be drawn from the results. As an application, we have planned the heating engineering for Yangyuan County in China, which demonstrates the feasibility and superiority of the method.

  5. Effect of surface treatment on the interfacial contact resistance and corrosion resistance of Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Yang, Meijun; Zhang, Dongming

    2014-01-01

    The bipolar plate is an important component of the PEMFC (polymer electrolyte membrane fuel cell) because it supplies the pathway of electron flow between each unit cell. Fe–Ni–Cr alloy is considered as a good candidate material for bipolar plate, but it is limited to use as a bipolar plate due to its high ICR (interfacial contact resistance) and corrosion problem. In order to explore a cost-effective method on surface modification, various chemical and electrochemical treatments are performed on Fe–Ni–Cr alloy to acquire the effect of the surface modification on the ICR and corrosion behavior. The ICR and corrosion resistance of Fe–Ni–Cr alloy can be effectively controlled by the chemical treatment of immersion in the mixed acid solution with 10 vol% HNO 3 , 2 vol% HCl and 1 vol% HF for 10 min at 65 °C and then was placed in 30 vol% HNO 3 solution for 5 min. The chemical treatment is more effective on reducing ICR and improving corrosion resistance than that of electrochemical methods (be carried out in the 2 mol/L H 2 SO 4 solution with the electrical potential from −0.4 V to 0.6 V) for Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells. - Highlights: • The procedure of the surface treatments on Fe–Ni–Cr alloy as bipolar plate was described in detail. • Effects of various surface treatments on the interfacial contact resistivity and corrosion behavior were discussed. • The mechanism of the surface modification was particularly analyzed

  6. Study of the resistance of SAMs on aluminium to acidic and basic solutions using dynamic contact angle measurement.

    Science.gov (United States)

    Liakos, Ioannis L; Newman, Roger C; McAlpine, Eoghan; Alexander, Morgan R

    2007-01-30

    We report the development of a method to determine the aqueous stability of self-assembled monolayers (SAMs) using the Wilhelmy plate dynamic contact angle (DCA) experiment. The DCA is measured in solutions over a range of pH values for alkyl carboxylic and alkyl phosphonic acid SAMs formed on magnetron-sputtered aluminum. The change in DCA on repeated immersion is used as a measure of the degradation of the SAMs by hydrolytic attack. The short and intermediate chain length alkyl acids are not stable in water of neutral pH, whereas molecules with the longest alkyl chains show considerably greater stability in neutral and both high and low pH solutions. The packing density inferred from the DCA and the contact angle hysteresis suggests the C18CO2H monolayer to be slightly less well packed than that of the C18P(=O)(OH)2; this is consistent with related friction force microscopy and infrared reflection absorption spectroscopy findings published elsewhere (Foster, T. T.; Alexander, M. R.; Leggett, G. J.; McAlpine, E. Langmuir 2006, 22, 9254-9259). The resistance of the SAMs to acid and alkaline environments is discussed in the context of aluminum oxide solubility, SAM packing density, and the resistance of the interfacial phosphate and carboxylate functionalities to different aqueous conditions.

  7. Improved Electron Transport with Reduced Contact Resistance in N-Doped Polymer Field-Effect Transistors with a Dimeric Dopant.

    Science.gov (United States)

    Wang, Rong; Guo, Yikun; Zhang, Di; Zhou, Huiqiong; Zhao, Dahui; Zhang, Yuan

    2018-01-15

    Attaining control on charge injection properties is significant for meaningful applications of organic field-effect transistors (OFETs). Here, molecular electron-doping is applied with an air-stable dimer dopant for n-type OFETs based on (naphthalene diimide-diketopyrrolopyrrole) polymer hosts. Through investigating the doping effect on contact and transport properties, it is found that the electron transport increases in n-doped OFETs at low doping regime with remaining large on/off ratios. These favorable meliorations are reconciled by the mitigated impacts of contact resistance and interfacial traps, as well as the surface morphology exhibiting features of increased ordering. The occurrence of doping in the presence of dimer dopants is evidenced by the observed shift of Fermi level toward vacuum level coupled with compositional analysis. Without applying vacuum-deposition-based contact doping, charge injection efficiencies are gained without losing OFET characteristics using the solution-based methodology. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Oxidation and contact resistance of Sn–Ag coated superconducting strands for the Large Hadron Collider (LHC)

    CERN Document Server

    Scheuerlein, C; Cantoni, M

    2006-01-01

    The oxides formed on the Sn-Ag coated LHC superconducting cables during a 200°C heat treatment in air are described and the oxide composition is compared with the interstrand contact resistance (Rc). The analysis of more than 250 interstrand contact areas shows that the higher the average Cu content with respect to the Sn content in the oxide, the higher is Rc. During the 200°C heat treatment, Sn in the coating is transformed into a Cu3Sn layer, on which an oxide grows that consists essentially of a thin outermost layer of CuO on top of Cu2O, similar to the oxide structure formed on bare Cu. The underlying Cu3Sn layer acts as an O diffusion barrier that prevents O diffusion into the Cu bulk during the subsequent cable heat treatment under high pressure. On contact zones where the Cu3Sn layer is not formed during the 200°C heat treatment mainly Sn oxide grows and Rc is comparatively low.

  9. Low resistivity molybdenum thin film towards the back contact of dye ...

    Indian Academy of Sciences (India)

    . 3.5 Electrical properties of Mo thin films. The electrical properties of 400 nm Mo thin films measured by four-point probe are listed in table 1. The lowest resistivity was 10.52E−06 cm (at 1 mA applied current) when the sputtering power 150 W.

  10. Low resistivity molybdenum thin film towards the back contact of dye ...

    Indian Academy of Sciences (India)

    The molybdenum thin film was grown on the glass substrate by direct current sputtering techniques of which the sputtering power was 150Wat 18 sccm flow rate of Ar. At such sputtering parameters, the Mo film can reach the lowest resistivity of 1.28E−6 cm at 400 nm thick. And the reflection of Mo membrane was 82%.

  11. Routine Use of Contact Precautions for Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococcus: Which Way Is the Pendulum Swinging?

    Science.gov (United States)

    Russell, Dana; Beekmann, Susan E; Polgreen, Philip M; Rubin, Zachary; Uslan, Daniel Z

    2016-01-01

    BACKGROUND Studies have suggested that contact precautions (CP) for methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococcus may have risks that outweigh the benefits. These risks, coupled with more widespread use of horizontal interventions such as daily bathing with chlorhexidine gluconate, have brought into question the value of routine CP for these organisms. OBJECTIVE To assess the state of utilization of CP as well as adjunctive measures to reduce the risk of transmission in US hospitals. DESIGN Cross-sectional survey. PARTICIPANTS Total of 751 physician members of the Emerging Infections Network. METHODS An 8-question electronic survey distributed by email. RESULTS A total of 426/751 (57%) responded to the survey; 337/364 (93%) of respondents use routine CP for methicillin-resistant S. aureus and 335/364 (92%) use routine CP for vancomycin-resistant enterococcus. The most widely used trigger for initiation of CP for both pathogens was positive clinical culture. Practices for discontinuation of isolation varied widely. We found that 325/354 (92%) perform routine chlorhexidine gluconate bathing and 236/353 (67%) perform S. aureus decolonization with mupirocin for 1 or more subsets of inpatients, and 82/356 (23%) reported using either hydrogen peroxide vapor or ultraviolet-C room disinfection at discharge. Free text responses noted frustration and variation in the application, practice, and process for initiation and discontinuation of CP. CONCLUSIONS Use of CP for methicillin-resistant S. aureus and vancomycin-resistant enterococcus remains commonplace, although horizontal interventions such as chlorhexidine gluconate bathing are increasingly used. The heterogeneity of practices and policies was striking. Evidence-based guidelines regarding CP and horizontal interventions are needed. Infect. Control Hosp. Epidemiol. 2015;37(1):36-40.

  12. Automated pipeline to analyze non-contact infrared images of the paraventricular nucleus specific leptin receptor knock-out mouse model

    Science.gov (United States)

    Diaz Martinez, Myriam; Ghamari-Langroudi, Masoud; Gifford, Aliya; Cone, Roger; Welch, E. B.

    2015-03-01

    Evidence of leptin resistance is indicated by elevated leptin levels together with other hallmarks of obesity such as a defect in energy homeostasis.1 As obesity is an increasing epidemic in the US, the investigation of mechanisms by which leptin resistance has a pathophysiological impact on energy is an intensive field of research.2 However, the manner in which leptin resistance contributes to the dysregulation of energy, specifically thermoregulation,3 is not known. The aim of this study was to investigate whether the leptin receptor expressed in paraventricular nucleus (PVN) neurons plays a role in thermoregulation at different temperatures. Non-contact infrared (NCIR) thermometry was employed to measure surface body temperature (SBT) of nonanesthetized mice with a specific deletion of the leptin receptor in the PVN after exposure to room (25 °C) and cold (4 °C) temperature. Dorsal side infrared images of wild type (LepRwtwt/sim1-Cre), heterozygous (LepRfloxwt/sim1-Cre) and knock-out (LepRfloxflox/sim1-Cre) mice were collected. Images were input to an automated post-processing pipeline developed in MATLAB to calculate average and maximum SBTs. Linear regression was used to evaluate the relationship between sex, cold exposure and leptin genotype with SBT measurements. Findings indicate that average SBT has a negative relationship to the LepRfloxflox/sim1-Cre genotype, the female sex and cold exposure. However, max SBT is affected by the LepRfloxflox/sim1-Cre genotype and the female sex. In conclusion this data suggests that leptin within the PVN may have a neuroendocrine role in thermoregulation and that NCIR thermometry combined with an automated imaging-processing pipeline is a promising approach to determine SBT in non-anesthetized mice.

  13. Saturation mapping of QTL region determining resistance specificity ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-09-01

    Sep 1, 2009 ... Genetic improvement for biotic resistance in rice involves the quantitative nature of inheritance, which reflects the additive effects of several genetic loci throughout the genome. To in silico identify putative candidate genes involved in defense response, we performed in silico anchoring of the QTL genetic.

  14. Saturation mapping of QTL region determining resistance specificity ...

    African Journals Online (AJOL)

    Genetic improvement for biotic resistance in rice involves the quantitative nature of inheritance, which reflects the additive effects of several genetic loci throughout the genome. To in silico identify putative candidate genes involved in defense response, we performed in silico anchoring of the QTL genetic marker data to the ...

  15. Moving towards high-power, high-frequency and low-resistance CNT supercapacitors by tuning the CNT length, axial deformation and contact resistance

    Science.gov (United States)

    Basiricò, L.; Lanzara, G.

    2012-08-01

    In this paper it is shown that the electrochemical behaviour of vertically aligned multi-walled carbon nanotube (VANT) supercapacitors is influenced by the VANTs’ length (electrode thickness), by their axial compression and by their interface with the current collector. It is found that the VANTs, which can be interpreted as a dense array of nanochannels, have an active area available to ions that is strongly affected by the electrode’s thickness and compressional state. Consequently, the tested thinner electrodes, compressed electrodes or a combination of the two were found to be characterized by a significant improvement in terms of power density (up to 1246%), knee frequency (58 822% working up to 10 kHz), equivalent series resistance (ESR, up to 67%) and capacitance (up to 21%) when compared with thicker and/or uncompressed electrodes. These values are significantly higher than those reported in the literature where long VANTs with no control on compression are typically used. It is also shown that the ESR can be reduced not only by using shorter and compressed VANTs that have a higher conductance or by improving the electrode/collector electrical contact by changing the contact morphology at the nanoscale through compression, but also by depositing a thin platinum layer on the VANT tips in contact with the current collector (73% ESR decrease).

  16. Involvement of a Novel Efflux System in Biofilm-Specific Resistance to Antibiotics▿

    OpenAIRE

    Zhang, Li; Mah, Thien-Fah

    2008-01-01

    Bacteria growing in biofilms are more resistant to antibiotics than their planktonic counterparts. How this transition occurs is unclear, but it is likely there are multiple mechanisms of resistance that act together in order to provide an increased overall level of resistance to the biofilm. We have identified a novel efflux pump in Pseudomonas aeruginosa that is important for biofilm-specific resistance to a subset of antibiotics. Complete deletion of the genes encoding this pump, PA1874 to...

  17. Electron transfer at the contact between Al electrode and gold nanoparticles of polymer: Nanoparticle resistive switching devices studied by alternating current impedance spectroscopy

    International Nuclear Information System (INIS)

    Ouyang, Jianyong

    2013-01-01

    Electron transfer at the contact between an Al electrode and Au nanoparticles of polymer:nanoparticle devices is studied by ac impedance spectroscopy. The devices have a polystyrene layer embedded with Au nanoparticles capped with conjugated 2-naphthalenethiol sandwiched between Al and MoO 3 /Al electrodes, and they exhibit electrode-sensitive resistive switches. The devices in the pristine or high resistance state have high capacitance. The capacitance decreases after the devices switch to a low resistance state by a voltage scan. The change in the capacitance is attributed to the voltage-induced change on the electronic structure of the contact between the Al electrode and Au nanoparticles

  18. Multi-channel conduction in redox-based resistive switch modelled using quantum point contact theory

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, E., E-mail: enrique.miranda@uab.cat; Suñé, J. [Departament d' Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallés, Barcelona (Spain); Mehonic, A.; Kenyon, A. J. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2013-11-25

    A simple analytic model for the electron transport through filamentary-type structures in Si-rich silica (SiO{sub x})-based resistive switches is proposed. The model is based on a mesoscopic description and is able to account for the linear and nonlinear components of conductance that arise from both fully and partially formed conductive channels spanning the dielectric film. Channels are represented by arrays of identical scatterers whose number and quantum transmission properties determine the current magnitude in the low and high resistance states. We show that the proposed model not only reproduces the experimental current-voltage (I-V) characteristics but also the normalized differential conductance (dln(I)/dln(V)-V) curves of devices under test.

  19. Research of the Resistance of Contact Welding Joint of R65 Type Rail

    Directory of Open Access Journals (Sweden)

    Kęstutis Dauskurdis

    2015-03-01

    Full Text Available In the article the R65 type rail joints that were welded by resistance welding are analysed. Survey methodology of the research consists of the following parts: visual inspection of welded joint, ultrasonic rail inspection, hardness test of upper part of the rail, fusion area research, the measurement hardness test of heat-softened area, the measurement microhardness test, microstructure research of the welded joint, impact strength experiments, chemical analysis of welded joint, wheel-rail interaction research using the finite element method (FEM. The results of the research are analysed and the quality of weld is evaluated. The conclusion is based on the results of this research.

  20. Thermal contact resistance measurement of conduction cooled binary current lead joint block in cryocooler based self field I-V characterization facility

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Ananya, E-mail: ananya@ipr.res.in; Das, Subrat Kumar; Agarwal, Anees Bano Pooja; Pradhan, Subrata [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2016-05-23

    In the present study thermal resistance of conduction cooled current lead joint block employing two different interfacial material namely AlN sheet and Kapton Film have been studied in the temperature range 5K-35K. In each case, the performance of different interlayer materials e.g. Indium foil for moderately pressurized contacts (contact pressure <1 MPa), and Apiezon N Grease, GE varnish for low pressurized contact (contact pressure <1 MPa) is studied. The performances of AlN joint with Indium foil and with Apeizon N Grease are studied and it is observed that the contact resistance reduces more with indium foil as compared to greased contact. The contact resistance measurements of Kapton film with Apiezon N grease and with GE varnish were also carried out in the same temperature range. A comparative study of AlN joint with Indium foil and Kapton with GE varnish as filler material is carried out to demonstrate better candidate material among Kapton and AlN for a particular filler material in the same temperature range.

  1. New antimicrobial contact catalyst killing antibiotic resistant clinical and waterborne pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Guridi, A. [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); Diederich, A.-K. [University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany); Aguila-Arcos, S.; Garcia-Moreno, M. [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); Blasi, R.; Broszat, M. [University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany); Schmieder, W.; Clauss-Lendzian, E. [Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany); Sakinc-Gueler, T. [University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Andrade, R. [Advanced Research Facilities (SGIker), University of the Basque Country, UPV/EHU, 48940 Leioa (Spain); Alkorta, I. [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); Meyer, C.; Landau, U. [Largentec GmbH, Am Waldhaus 32, 14129 Berlin (Germany); Grohmann, E., E-mail: elisabeth.grohmann@googlemail.com [Biophysics Unit (CSIC, UPV/EHU), Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa (Spain); University Medical Center Freiburg, Division of Infectious Diseases, Hugstetter Strasse 55, 79106 Freiburg (Germany); Biology II, Microbiology, Albert-Ludwigs-University Freiburg, Schänzlestrasse 1, 79104 Freiburg (Germany)

    2015-05-01

    Microbial growth on medical and technical devices is a big health issue, particularly when microorganisms aggregate to form biofilms. Moreover, the occurrence of antibiotic-resistant bacteria in the clinical environment is dramatically growing, making treatment of bacterial infections very challenging. In search of an alternative, we studied a novel antimicrobial surface coating based on micro galvanic elements formed by silver and ruthenium with surface catalytic properties. The antimicrobial coating efficiently inhibited the growth of the nosocomial pathogens Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Enterococcus faecium as demonstrated by the growth inhibition on agar surface and in biofilms of antibiotic resistant clinical E. faecalis, E. faecium, and S. aureus isolates. It also strongly reduced the growth of Legionella in a drinking water pipeline and of Escherichia coli in urine. We postulate a mode of action of the antimicrobial material, which is independent of the release of silver ions. Thus, the novel antimicrobial coating could represent an alternative to combat microbial growth avoiding the toxic side effects of high levels of silver ions on eukaryotic cells. - Highlights: • The novel antimicrobial inhibits growth of clinical staphylococci and enterococci. • The novel antimicrobial inhibits growth of Legionella in drinking water. • A putative mode of action of the antimicrobial coating is presented.

  2. New antimicrobial contact catalyst killing antibiotic resistant clinical and waterborne pathogens

    International Nuclear Information System (INIS)

    Guridi, A.; Diederich, A.-K.; Aguila-Arcos, S.; Garcia-Moreno, M.; Blasi, R.; Broszat, M.; Schmieder, W.; Clauss-Lendzian, E.; Sakinc-Gueler, T.; Andrade, R.; Alkorta, I.; Meyer, C.; Landau, U.; Grohmann, E.

    2015-01-01

    Microbial growth on medical and technical devices is a big health issue, particularly when microorganisms aggregate to form biofilms. Moreover, the occurrence of antibiotic-resistant bacteria in the clinical environment is dramatically growing, making treatment of bacterial infections very challenging. In search of an alternative, we studied a novel antimicrobial surface coating based on micro galvanic elements formed by silver and ruthenium with surface catalytic properties. The antimicrobial coating efficiently inhibited the growth of the nosocomial pathogens Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Enterococcus faecium as demonstrated by the growth inhibition on agar surface and in biofilms of antibiotic resistant clinical E. faecalis, E. faecium, and S. aureus isolates. It also strongly reduced the growth of Legionella in a drinking water pipeline and of Escherichia coli in urine. We postulate a mode of action of the antimicrobial material, which is independent of the release of silver ions. Thus, the novel antimicrobial coating could represent an alternative to combat microbial growth avoiding the toxic side effects of high levels of silver ions on eukaryotic cells. - Highlights: • The novel antimicrobial inhibits growth of clinical staphylococci and enterococci. • The novel antimicrobial inhibits growth of Legionella in drinking water. • A putative mode of action of the antimicrobial coating is presented

  3. Clostridium difficile Infection and Patient-Specific Antimicrobial Resistance Testing Reveals a High Metronidazole Resistance Rate.

    Science.gov (United States)

    Barkin, Jodie A; Sussman, Daniel A; Fifadara, Nimita; Barkin, Jamie S

    2017-04-01

    Clostridium difficile (CD) infection (CDI) causes marked morbidity and mortality, accounting for large healthcare expenditures annually. Current CDI treatment guidelines focus on clinical markers of patient severity to determine the preferred antibiotic regimen of metronidazole versus vancomycin. The antimicrobial resistance patterns for patients with CD are currently unknown. The aim of this study was to define the antimicrobial resistance patterns for CD. This study included all patients with stools sent for CD testing to a private laboratory (DRG Laboratory, Alpharetta, Georgia) in a 6-month period from across the USA. Patient data was de-identified, with only age, gender, and zip-code available per laboratory protocol. All samples underwent PCR testing followed by hybridization for CD toxin regions A and B. Only patients with CD-positive PCR were analyzed. Antimicrobial resistance testing using stool genomic DNA evaluated presence of imidazole- and vancomycin-resistant genes using multiplex PCR gene detection. Of 2743, 288 (10.5%) stool samples were positive for CD. Six were excluded per protocol. Of 282, 193 (69.4%) were women, and average age was 49.4 ± 18.7 years. Of 282, 62 were PCR positive for toxins A and B, 160 for toxin A positive alone, and 60 for toxin B positive alone. Antimicrobial resistance testing revealed 134/282 (47.5%) patients resistant to imidazole, 17 (6.1%) resistant to vancomycin, and 9 (3.2%) resistant to imidazole and vancomycin. CD-positive patients with presence of imidazole-resistant genes from stool DNA extract was a common phenomenon, while vancomycin resistance was uncommon. Similar to treatment of other infections, antimicrobial resistance testing should play a role in CDI clinical decision-making algorithms to enable more expedited and cost-effective delivery of patient care.

  4. Mutations in wheat exhibiting growth-stage-specific resistance to biotrophic fungal pathogens.

    Science.gov (United States)

    Smith, Phil H; Howie, John A; Worland, Anthony J; Stratford, Rebecca; Boyd, Lesley A

    2004-11-01

    Two mutants were isolated in wheat that showed enhanced resistance towards Puccinia striiformis f. sp. tritici, the fungal causal agent of yellow rust. The altered phenotype of I3-48 is due to a minimum of two mutation events, each showing a partial, additive effect, with one mutation segregating with a deletion on the long arm of chromosome 4D. In the case of I3-54, the enhanced resistance is due to a single, dominant mutation. In both mutants, the expression of the enhanced resistance is growth-stage specific. With I3-54, the full resistance phenotype is apparent from the third seedling leaf onwards, while with I3-48, a full resistance phenotype is only seen on the tenth and subsequent leaves. In addition to the enhanced resistance towards yellow rust, I3-48 also shows enhanced resistance towards brown rust, and I3-54 shows enhanced resistance to powdery mildew.

  5. Slip-rolling resistance of novel Zr(C,N) thin film coatings under high Hertzian contact pressures

    Energy Technology Data Exchange (ETDEWEB)

    Manier, Charles-Alix

    2010-08-24

    Today, coatings are used in many applications ranging from the decoration purposes to the improvement of efficiency such as in machining tools, medical tools, computer devices (hard disks) and many more. Especially the automotive industry anticipates a benefit in using coatings for example in powertrains and gears where the mechanical components are stressed under slip-rolling motion. A cost effective option to increase efficiency is based on the increase of the load carrying capacity by thin film coatings. It would also represent a way towards downsizing. In the work presented here, a small review concerning rolling contact fatigue of coatings was performed. Experimentally it is then shown, that crystalline Zr(C,N) coatings can be slip-rolling resistant at 120 C in factory fill engine oil up to ten million cycles under average Hertzian contact pressures up to P{sub 0mean} = 1.94 GPa (P{sub 0max} = 2.91 GPa). Basically, it represents here the doubling of the normal force acting on the surface compared to uncoated steel traditionally lubricated with fully formulated oil. Typically, the coated substrates are made of the quenched and tempered bearing steel Cronidur 30. The Zr(C,N) coatings were fully characterized using different characterisation techniques in order to understand the difference in slip-rolling resistance under those high tribological demands. Effectively, the slip-rolling resistance of different batches of the Zr(C,N) coatings is evaluated using a defined and powerful testing procedure. Different results of lifetime were achieved without fundamental changes of the deposition procedure. The characterisation achieved permits the identification of microstructural disparities which should affect the load carrying capacity of the coating. Moreover, the efficiency of the high slip-rolling resistant Zr(C,N) coating was considered not only with respect to the improvement of the load carrying capacity of the substrate but also in terms of tribological

  6. Rolling-contact fatigue resistance of hard coatings on bearing steels.

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.

    1999-08-18

    Ball- and roller-bearings of the 21st Century are expected to perform better and last longer while operating under more stringent conditions than before. To meet these great expectations, researchers have been constantly exploring new bearing designs or refining existing ones, optimizing microstructure and chemistry of bearing materials, and alternatively, they have been considering the use of thin hard coatings for improved bearing performance and durability. Already, some laboratory tests have demonstrated that hard nitride, carbide (such as TiN, TiC, etc.) and diamondlike carbon (DLC) coatings can be very effective in prolonging the fatigue lives of bearing steels. This paper provides an overview of the recent developments in hard coatings for bearing applications. Previous studies have demonstrated that thin, hard coatings can effectively prolong the fatigue lives of bearing steel substrates. In particular, thinner hard coatings (i.e., 0.2 - 1 {micro}m thick) provide exceptional improvements in the fatigue lives of bearing steel substrates. In contrast, thicker hard coatings suffer micro fracture and delamination when tested under high contact stresses, hence are ineffective and may even have a negative effect on bearing life. Overall, it was concluded that thin hard coatings may offer new possibilities for bearing industry in meeting the performance and durability needs of the 21st Century.

  7. Risk Factors for Carbapenemase-Producing Carbapenem-Resistant Enterobacteriaceae (CP-CRE) Acquisition Among Contacts of Newly Diagnosed CP-CRE Patients.

    Science.gov (United States)

    Schwartz-Neiderman, Anat; Braun, Tali; Fallach, Noga; Schwartz, David; Carmeli, Yehuda; Schechner, Vered

    2016-10-01

    OBJECTIVE Carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) are extremely drug-resistant pathogens. Screening of contacts of newly identified CP-CRE patients is an important step to limit further transmission. We aimed to determine the risk factors for CP-CRE acquisition among patients exposed to a CP-CRE index patient. METHODS A matched case-control study was performed in a tertiary care hospital in Israel. The study population was comprised of patients who underwent rectal screening for CP-CRE following close contact with a newly identified CP-CRE index patient. Cases were defined as positive tests for CP-CRE. For each case patient, 2 matched controls were randomly selected from the pool of contacts who tested negative for CP-CRE following exposure to the same index case. Bivariate and multivariate analyses were conducted using conditional logistic regression. RESULTS In total, 53 positive contacts were identified in 40 unique investigations (896 tests performed on 735 contacts) between October 6, 2008, and June 7, 2012. bla KPC was the only carbapenemase identified. In multivariate analysis, risk factors for CP-CRE acquisition among contacts were (1) contact with an index patient for ≥3 days (odds ratio [OR], 9.8; 95% confidence interval [CI], 2.0-48.9), (2) mechanical ventilation (OR, 4.1; 95% CI, 1.4-11.9), and (3) carriage or infection with another multidrug-resistant organism (MDRO; OR, 2.6; 95% CI, 1.0-7.1). Among patients who received antibiotics, cephalosporins were associated with a lower risk of acquisition. CONCLUSIONS Patient characteristics (ventilation and carriage of another MDRO) as well as duration of contact are risk factors for CP-CRE acquisition among contacts. The role of cephalosporins requires further study. Infect Control Hosp Epidemiol 2016;1-7.

  8. Resistive wall mode control code maturity: progress and specific examples

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yueqiang; Chapman, I T; Gimblett, C G; Hastie, R J; Hender, T C [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Chu, M S; Garofalo, A M; Jackson, G L; La Haye, R J [General Atomics, San Diego, CA 92186-5608 (United States); Guo, W F [ASIPP Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Villone, F; Ambrosino, G [ENEA/CREATE, DAEIMI, Universita di Cassino, Via di Biasio 43, Cassino (France) (Italy); Albanese, R [ENEA/CREATE, Universita Federico II di Napoli, Via Claudio 21, Napoli (Italy); Baruzzo, M; Bolzonella, T; Marchiori, G; Paccagnella, R [Consorzio RFX, Corso Stati Uniti 4, Padova, 35127 (Italy); Lanctot, M J [Columbia University, 2960 Broadway, New York, NY 10027-6902 (United States); In, Y [FAR-TECH, Inc., 3550 General Atomics Court, San Diego, CA (United States); Okabayashi, M, E-mail: yueqiang.liu@ccfe.ac.u [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States)

    2010-10-15

    Two issues of the resistive wall mode (RWM) control code maturity are addressed: the inclusion of advanced mode damping physics beyond the ideal MHD description, and the possibility of taking into account the influence of 3D features of the conducting structures on the mode stability and control. Examples of formulations and computational results are given, using the MARS-F/K codes and the CarMa code. The MARS-K calculations for a DIII-D plasma shows that the fast ion contributions, which can give additional drift kinetic stabilization in the perturbative approach, also drive an extra unstable branch of mode in the self-consistent kinetic modelling. The CarMa modelling for the ITER steady state advanced plasmas shows about 20% reduction in the RWM growth rate by the volumetric blanket modules. The multi-mode analysis predicts a weak interaction between the n = 0 and the n = 1 RWMs, due to the 3D ITER walls. The CarMa code is also successfully applied to model the realistic feedback experiments in RFX.

  9. Dihydrolipoamide dehydrogenase-Lpd (Rv0462)-specific T cell recall responses are higher in healthy household contacts of TB: a novel immunodominant antigen from M. tuberculosis.

    Science.gov (United States)

    Devasundaram, Santhi; Raja, Alamelu

    2017-07-01

    The partial effectiveness against pulmonary tuberculosis (PTB), displayed by the existing tuberculosis (TB) vaccine, bacillus Calmette-Guérin (BCG), highlights the need for novel vaccines to replace or improve BCG. In TB immunology, antigen-specific cellular immune response is frequently considered indispensable. Latency-associated antigens are intriguing as targets for TB vaccine development. The mycobacterial protein, dihydrolipoamide dehydrogenase (Lpd; Rv0462), the third enzyme of the pyruvate dehydrogenase (PDH) complex, facilitates Mycobacterium tuberculosis to resist host reactive nitrogen intermediates. Multicolor flow cytometry analysis of whole-blood cultures showed higher Lpd-specific Th1 recall response (IFN-γ, TNF-α, and IL-2; P = 0.0006) and memory CD4 + and CD8 + T cells (CCR7 + CD45RA - and CCR7 - CD45RA - ) in healthy household contacts (HHC) of TB ( P < 0.0001), which is comparable with or higher than the standard antigens, ESAT-6 and CFP-10. The frequency of Lpd-specific multifunctional T cells was higher in HHC compared with PTB patients. However, there is no significant statistical correlation. Regulatory T cell (T reg ) analysis of HHCs and active TB patients demonstrated very low Lpd-specific CD4 + T regs relative to ESAT-6 and CFP-10. Our study demonstrates that the Lpd antigen induces a strong cellular immune response in healthy mycobacteria-infected individuals. In consideration of this population having demonstrated immunologic protection against active TB disease development, our data are encouraging about the possible use of Lpd as a target for further TB subunit vaccine development. © Society for Leukocyte Biology.

  10. Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes normally are used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium-nickel steels in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

  11. Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes are normally used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0% and nickel does not exceed 50.0%

  12. Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes are normally used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

  13. Involvement of a Novel Efflux System in Biofilm-Specific Resistance to Antibiotics▿

    Science.gov (United States)

    Zhang, Li; Mah, Thien-Fah

    2008-01-01

    Bacteria growing in biofilms are more resistant to antibiotics than their planktonic counterparts. How this transition occurs is unclear, but it is likely there are multiple mechanisms of resistance that act together in order to provide an increased overall level of resistance to the biofilm. We have identified a novel efflux pump in Pseudomonas aeruginosa that is important for biofilm-specific resistance to a subset of antibiotics. Complete deletion of the genes encoding this pump, PA1874 to PA1877 (PA1874-1877) genes, in an P. aeruginosa PA14 background results in an increase in sensitivity to tobramycin, gentamicin, and ciprofloxacin, specifically when this mutant strain is growing in a biofilm. This efflux pump is more highly expressed in biofilm cells than in planktonic cells, providing an explanation for why these genes are important for biofilm but not planktonic resistance to antibiotics. Furthermore, expression of these genes in planktonic cells increases their resistance to antibiotics. We have previously shown that ndvB is important for biofilm-specific resistance (T. F. Mah, B. Pitts, B. Pellock, G. C. Walker, P. S. Stewart, and G. A. O'Toole, Nature 426:306-310, 2003). Our discovery that combining the ndvB mutation with the PA1874-1877 gene deletion results in a mutant strain that is more sensitive to antibiotics than either single mutant strain suggests that ndvB and PA1874-1877 contribute to two different mechanisms of biofilm-specific resistance to antibiotics. PMID:18469108

  14. Involvement of a novel efflux system in biofilm-specific resistance to antibiotics.

    Science.gov (United States)

    Zhang, Li; Mah, Thien-Fah

    2008-07-01

    Bacteria growing in biofilms are more resistant to antibiotics than their planktonic counterparts. How this transition occurs is unclear, but it is likely there are multiple mechanisms of resistance that act together in order to provide an increased overall level of resistance to the biofilm. We have identified a novel efflux pump in Pseudomonas aeruginosa that is important for biofilm-specific resistance to a subset of antibiotics. Complete deletion of the genes encoding this pump, PA1874 to PA1877 (PA1874-1877) genes, in an P. aeruginosa PA14 background results in an increase in sensitivity to tobramycin, gentamicin, and ciprofloxacin, specifically when this mutant strain is growing in a biofilm. This efflux pump is more highly expressed in biofilm cells than in planktonic cells, providing an explanation for why these genes are important for biofilm but not planktonic resistance to antibiotics. Furthermore, expression of these genes in planktonic cells increases their resistance to antibiotics. We have previously shown that ndvB is important for biofilm-specific resistance (T. F. Mah, B. Pitts, B. Pellock, G. C. Walker, P. S. Stewart, and G. A. O'Toole, Nature 426:306-310, 2003). Our discovery that combining the ndvB mutation with the PA1874-1877 gene deletion results in a mutant strain that is more sensitive to antibiotics than either single mutant strain suggests that ndvB and PA1874-1877 contribute to two different mechanisms of biofilm-specific resistance to antibiotics.

  15. Characterization of bilayer-metal contacts to high Tc superconducting films

    International Nuclear Information System (INIS)

    Ma, Q.Y.; Schmidt, M.T.; Weinman, L.S.; Yang, E.S.; Sampere, S.M.; Chan, S.

    1991-01-01

    Low resistivity normal metal contacts to YBa 2 Cu 3 O 7-x (YBCO) films have been investigated. It has previously shown that the contact resistivity of Au contact exhibits a strong temperature dependence, decreasing 2--3 orders of magnitude at a transition temperature near T c of YBCO film. Other metal contacts, including Pd and Nb, do not show this effect. The contact resistivity of metal contacts has been correlated with interfacial reactions and disruption studied by x-ray photoelectron spectroscopy (XPS). In this work we demonstrate that a thin interlayer, specifically 10 A of Au, between the YBCO and a metal contact such as Nb can allow the formation of a low resistance contact. XPS of the effect of the interlayer is presented, and the implications for carrier coupling are discussed. These results indicate a methodology for low contact resistance bilayer-metal structures for supercondcuting device applications

  16. Effect of specific resistance training on forearm pain and work disability in industrial technicians: cluster randomised controlled trial

    DEFF Research Database (Denmark)

    Andersen, Lars Louis; Jakobsen, Markus D; Pedersen, Mogens Theisen

    2012-01-01

    To determine the effect of specific resistance training on forearm pain and work disability in industrial technicians.......To determine the effect of specific resistance training on forearm pain and work disability in industrial technicians....

  17. Time-temperature influence on the corrosion resistance of Ni-Cr-Nb superalloys in contact with Na2SO4-V2O5 molten mixtures

    International Nuclear Information System (INIS)

    Otero, E.; Pardo, A.; Hernaez, J.; Hierro, P.

    1990-01-01

    Corrosion rate data obtained by the polarization resistance method in nickel-base superalloys in contact with Na 2 SO 4 -V 2 O 5 molten mixtures are presented. The instrumental technique is also described. Time-temperature influence on the corrosion kinetics in the described conditions is discussed (Author)

  18. Rapid identification of rice blast resistance gene by specific length amplified fragment sequencing

    Directory of Open Access Journals (Sweden)

    Shen Chen

    2016-05-01

    Full Text Available Excavation of resistance genes is one of the most effective and environment-friendly measures to control the devastating rice disease caused by Magnaporthe oryzae. Many resistance genes have been mapped and characterized in the last century. Nevertheless, only a few of the total resistance genes could be really applied in the rice breeding program. Huazhan (HZ is a new native rice restorer line developed in China and widely used in hybrid rice in recent years. HZ and its crossed combinations usually show a broad spectrum of resistance against rice blast in different rice ecosystems in China. Dissection of the genetic background of HZ is very useful for its further application. In this study, a combined method based on bulked segregation analysis (BSA and specific length amplified fragment sequencing (SLAF-seq was used to identify blast resistance gene(s in HZ. A total of 56,187 SLAFs labels were captured and 9051 polymorphic SLAFs markers were analysed and procured in this study. One trait associated with candidate resistance genes region on chromosome 12 overlapping 10.2–17.6 Mb has been identified, in which 10 NBS-LRR (nucleotide-binding site-leucine-rich repeat coding genes were used as resistance gene candidates. Our result indicated that SLAF-seq with BSA is a rapid and effective method for initial identification of blast resistance genes. The identification of resistance gene in HZ will improve its molecular breeding and resistance variety application.

  19. Specificity of a Rust Resistance Suppressor on 7DL in the Spring Wheat Cultivar Canthatch.

    Science.gov (United States)

    Talajoor, Mina; Jin, Yue; Wan, Anmin; Chen, Xianming; Bhavani, Sridhar; Tabe, Linda; Lagudah, Evans; Huang, Li

    2015-04-01

    The spring wheat 'Canthatch' has been shown to suppress stem rust resistance genes in the background due to the presence of a suppressor gene located on the long arm of chromosome 7D. However, it is unclear whether the suppressor also suppresses resistance genes against leaf rust and stripe rust. In this study, we investigated the specificity of the resistance suppression. To determine whether the suppression is genome origin specific, chromosome location specific, or rust species or race specific, we introduced 11 known rust resistance genes into the Canthatch background, including resistance to leaf, stripe, or stem rusts, originating from A, B, or D genomes and located on different chromosome homologous groups. F1 plants of each cross were tested with the corresponding rust race, and the infection types were scored and compared with the parents. Our results show that the Canthatch 7DL suppressor only suppressed stem rust resistance genes derived from either the A or B genome, and the pattern of the suppression is gene specific and independent of chromosomal location.

  20. Sex-specific responses to vocal convergence and divergence of contact calls in orange-fronted conures (Aratinga canicularis)

    DEFF Research Database (Denmark)

    Balsby, Thorsten J S; Scarl, Judith C

    2008-01-01

    We investigated the signal function of vocal imitation of contact calls in orange-fronted conures (OFCs; Aratinga canicularis) in Costa Rica. OFCs live in dynamic social systems with frequent flock fusions and fissions. Exchanges of contact calls precede these flock changes. During call exchanges...

  1. Specific kinesin expression profiles associated with taxane resistance in basal-like breast cancer.

    Science.gov (United States)

    Tan, Min Han; De, Sarmishtha; Bebek, Gurkan; Orloff, Mohammed S; Wesolowski, Robert; Downs-Kelly, Erinn; Budd, G Thomas; Stark, George R; Eng, Charis

    2012-02-01

    Breast cancer is a genetically heterogenous disease with subtypes differing in prognosis and chemosensitivity. The basal-like breast cancer (BLBC) molecular subtype is associated with poorer outcomes, but is more responsive to taxane-based chemotherapy. Kinesins are intracellular transport proteins that interact with microtubules, which are also the mechanistic target for taxanes. We investigated the relationship between taxane resistance in BLBC and kinesins using both expression and functional studies. Kinesin (KIF) expression was evaluated in three settings in relation to taxane resistance: (i) the NCI-60 cancer cell lines, (ii) pre-treatment samples from four BLBC patient cohorts receiving neoadjuvant chemotherapy regimens with and without taxanes, and (iii) post-treatment samples from residual breast cancer following neoadjuvant taxane-containing chemotherapy. We used a novel functional approach to gene modification, validation-based insertional mutagenesis, to select kinesin-overexpressing clones of BLBC cells for evaluation of related mechanisms of taxane resistance. In the NCI-60 cell line dataset, overexpression of the kinesin KIFC3 is significantly correlated with resistance to both docetaxel (P resistance to paclitaxel in the MDACC cohorts (P = 0.01); no KIF predicted resistance to fluorouracil-epirubicin-cyclophosphamide or cisplatin in BLBC patient cohorts treated without taxanes. KIF12 is the most overexpressed KIF gene in post-chemotherapy taxane-resistant residual breast cancers (2.8-fold-change). Functional studies established that overexpression of KIFC3, KIF5A, and KIF12 were specific in mediating resistance to docetaxel and not vincristine or doxorubicin. Mutation of the ATP-binding domain of a kinesin abolished its ability to mediate docetaxel resistance. Overall, kinesin overexpression correlates with specific taxane resistance in BLBC cell lines and tissues. Our results suggest a novel approach for drug development to overcome taxane

  2. [Children exposed to multidrug-resistant tuberculosis: How should we manage? Analysis of 46 child contacts and review of the literature].

    Science.gov (United States)

    Catho, G; Sénéchal, A; Ronnaux-Baron, A-S; Valour, F; Perpoint, T; Bouaziz, A; Dumitriescu, O; Reix, P; Pedone, C; Ader, F

    2015-12-01

    Tuberculosis-related morbidity and mortality remain important. Emergence and diffusion of multidrug-resistance tuberculosis (MDR-TB) is a global public health concern. Cases of MDR-TB in children are a sentinel event indicating the spread of a mycobacterial strain within a community. Latent TB precedes MDR-TB and screening and follow-up of contact individuals are key points of TB infection control. We performed the case-investigation of 20 adult cases of MDR-TB managed in our institution. Forty-six pediatric contact individuals were identified. A high proportion of these children were lost to follow-up (80% at 12 months), showing that monitoring this reservoir population with migrant history is challenging. Five (11%) children presented a secondary infection: one child was diagnosed with active TB infection (positive tuberculin skin test associated with abnormalities on chest computer tomography [CT] scan). Four children were diagnosed with latent TB infection (isolated positive tuberculin skin test with normal CT scan). Two of these children received a treatment adjusted to the strain of the index case. In the setting of emerging MDR-TB, tuberculin skin test may be likely replaced by specific interferon-gamma release assays (IGRA), independent of prior BCG vaccination. In addition, chest CT scan is preferred to chest X-ray to detect TB lesions. The management of latent TB infection is controversial: immediate treatment with second-line anti-TB drugs adapted to the index case strain or, consistently with WHO guidelines, a simple follow-up with subsequent treatment in case of active TB. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  3. A novel Capsicum gene inhibits host-specific disease resistance to Phytophthora capsici.

    Science.gov (United States)

    Reeves, Gregory; Monroy-Barbosa, Ariadna; Bosland, Paul W

    2013-05-01

    A novel disease resistance inhibitor gene (inhibitor of P. capsici resistance [Ipcr]), found in the chile pepper (Capsicum annuum) variety 'New Mexico Capsicum Accession 10399' (NMCA10399), inhibits resistance to Phytophthora capsici but not to other species of Phytophthora. When a highly P. capsici-resistant variety was hybridized with NMCA10399, the resultant F1 populations, when screened, were completely susceptible to P. capsici for root rot and foliar blight disease syndromes, despite the dominance inheritance of P. capsici resistance in chile pepper. The F2 population displayed a 3:13 resistant-to-susceptible (R:S) ratio. The testcross population displayed a 1:1 R:S ratio, and a backcross population to NMCA10399 displayed complete susceptibility. These results demonstrate the presence of a single dominant inhibitor gene affecting P. capsici resistance in chile pepper. Moreover, when lines carrying the Ipcr gene were challenged against six Phytophthora spp., the nonhost resistance was not overcome. Therefore, the Ipcr gene is interfering with host-specific resistance but not the pathogen- or microbe-associated molecular pattern nonhost responses.

  4. Resistance against Schistosoma mansoni induced by highly irradiated infections: studies on species specificity of immunization and attempts to transfer resistance

    International Nuclear Information System (INIS)

    Bickle, Q.D.; Andrews, B.J.; Doenhoff, M.J.; Ford, M.J.; Taylor, M.G.

    1985-01-01

    Significant levels of resistance against Schistosoma mansoni challenge were developed by mice exposed to highly irradiated (20 krad.) cercariae of the homologous species (53-67%), whereas vaccination with S. bovis, S. haematobium or S. japonicum failed to confer significant levels of resistance (-5-12%), thus confirming the specificity of the immunizing procedure. Attempts to transfer resistance to naive recipients by injection of serum and of spleen or lymph node cells from donor mice vaccinated with highly irradiated cercariae were largely unsuccessful. However, significant levels of resistance could be transferred to mice by injection of serum from rabbits exposed to irradiated cercariae. Comparable levels of resistance were conferred by injection of serum at the time of challenge (34-69%) or 5-6 days later (31-56%). In contrast, sera from rabbits injected with soluble egg antigen or homogenized cercariae failed to confer protection upon recipient mice. Sera from vaccinated mice, vaccinated rabbits and antigen-injected rabbits all caused cell adherence to skin-transformed schistosomula but neither the level of adherence nor the serum titre correlated with the ability to confer protection to mice. (author)

  5. Identification of Genes Involved in Pseudomonas aeruginosa Biofilm-Specific Resistance to Antibiotics

    OpenAIRE

    Zhang, Li; Fritsch, Meredith; Hammond, Lisa; Landreville, Ryan; Slatculescu, Cristina; Colavita, Antonio; Mah, Thien-Fah

    2013-01-01

    Pseudomonas aeruginosa is a key opportunistic pathogen characterized by its biofilm formation ability and high-level multiple antibiotic resistance. By screening a library of random transposon insertion mutants with an increased biofilm-specifc antibiotic susceptibility, we previously identified 3 genes or operons of P. aeruginosa UCBPP-PA14 (ndvB, PA1875-1877 and tssC1) that do not affect biofilm formation but are involved in biofilm-specific antibiotic resistance. In this study, we demonstr...

  6. Racing with friends: Resistance to peer influence, gist and specific risk beliefs.

    Science.gov (United States)

    Mirman, Jessica H; Curry, Allison E

    2016-11-01

    Studies assessing young drivers' risk appraisals with their driving behavior have shown both positive and inverse associations, possibly due to differences in survey items that cue gist appraisals about risk (i.e., beliefs that are focused on meaning) or specific appraisals (i.e., beliefs that are focused on discrete instances). Prior research has indicated that gist-based reasoning is protective against engaging in risk behavior and that use of gist appraisals increases with development. Additionally, although much of adolescents' risk-taking occurs in groups, almost no research examines how adolescents' resistance to peer influence may relate to their specific and gist beliefs about socially-bound risk behavior, as well as their future engagement in such behavior. One hundred and thirty-two adolescent drivers participated in a prospective self-report study on racing behavior. Surveys measured specific and gist risk appraisals, resistance to peer influence, and racing behavior at two time points three months apart. We hypothesized that stronger specific appraisals would be associated with greater likelihood of racing, and stronger gist appraisals would be protective. Further, we hypothesized that resistance to peer influence would be positively associated with gist appraisals and negatively associated with specific risk appraisals; and would also be inversely associate with racing. Specific risk appraisals and gist appraisals were predictive of racing behavior as hypothesized. Resistance to peer influence did not predict racing, but was associated with each type of risk appraisal as predicted at Time 1, although the association between specific risk and resistance to peer influence was non-significant at the second time point. Gist beliefs and the ability to resist influence from friends might be indicative of an underlying strength of one's own beliefs about the self as a non-risk taking person who stands up for his or her beliefs, which is protective against

  7. Pneumatic muscle actuator (PMA) task-specific resistance for potential use in microgravity exercise.

    Science.gov (United States)

    Hall, Kara L; Phillips, Chandler A; Reynolds, David B; Mohler, Stanley R; Neidhard-Doll, Amy T

    2012-07-01

    A pneumatic muscle actuator (PMA) is a device that mimics the behavior of skeletal muscle by contracting and generating force when activated. This type of actuator has a high power to weight ratio and unique characteristics which make it ideal for human interaction. PMAs, however, are difficult to control due to nonlinear dynamics. Our objective was to control a PMA as a source of task-specific resistance in simulated isokinetic strength training. Task-specific resistance will benefit those in need of strength training through a joint's range of motion, including astronauts who need to counteract muscle atrophy during prolonged spaceflight. The lightweight, clean, and compact PMA driven by pressurized air is able to produce resistance in microgravity. An open-loop control method based on a three-element phenomenological inverse model was developed to control the PMA. A motor was simultaneously controlled to act as simulated human quadriceps working against the PMA-produced resistance. For ankle weight replacement resistance profiles, the PMA control method produced resistance and PMA displacement tracking errors (RMSE) of 0.36-1.61 Nm and 0.55-1.59 mm, respectively. Motor position (simulated joint angle) tracking errors ranged from 0.47 to 2.82 degrees. Results indicate that the inverse model based control system produces task-specific PMA resistance and displacement. Closed-loop motor control was able to simulate isokinetic movement successfully. More complicated resistance profiles reveal the need for closed-loop control. Future work focuses on advancing both the PMA control strategies and the capabilities of the human simulator so that actual human operator applications can be realized.

  8. Streptomycin Resistance and Lineage-Specific Polymorphisms in Mycobacterium tuberculosis gidB Gene ▿

    Science.gov (United States)

    Spies, Fernanda S.; Ribeiro, Andrezza W.; Ramos, Daniela F.; Ribeiro, Marta O.; Martin, Anandi; Palomino, Juan Carlos; Rossetti, Maria Lucia R.; da Silva, Pedro Eduardo A.; Zaha, Arnaldo

    2011-01-01

    Mutations related to streptomycin resistance in the rpsL and rrs genes are well known and can explain about 70% of this phenotypic resistance. Recently, the gidB gene was found to be associated with low-level streptomycin resistance in Mycobacterium tuberculosis. Mutations in gidB have been reported with high frequency, and this gene appears to be very polymorphic, with frameshift and point mutations occurring in streptomycin-susceptible and streptomycin-resistant strains. In this study, mutations in gidB appeared in 27% of streptomycin-resistant strains that contained no mutations in the rpsL or rrs genes, and they were associated with low-level streptomycin resistance. However, the association of certain mutations in gidB with streptomycin resistance needs to be further investigated, as we also found mutations in gidB in streptomycin-susceptible strains. This occurred only when the strain was resistant to rifampin and isoniazid. Two specific mutations appeared very frequently in this and other studies of streptomycin-susceptible and -resistant strains; these mutations were not considered related to streptomycin resistance, but as a polymorphism. We stratified the strains according to the different phylogenetic lineages and showed that the gidB16 polymorphism (16G allele) was exclusively present in the Latin American-Mediterranean (LAM) genotype, while the gidB92 polymorphism (92C allele) was associated with the Beijing lineage in another population. In the sample studied, the two characterized single-nucleotide polymorphisms could distinguish LAM and Beijing lineages from the other lineages. PMID:21593257

  9. Streptomycin resistance and lineage-specific polymorphisms in Mycobacterium tuberculosis gidB gene.

    Science.gov (United States)

    Spies, Fernanda S; Ribeiro, Andrezza W; Ramos, Daniela F; Ribeiro, Marta O; Martin, Anandi; Palomino, Juan Carlos; Rossetti, Maria Lucia R; da Silva, Pedro Eduardo A; Zaha, Arnaldo

    2011-07-01

    Mutations related to streptomycin resistance in the rpsL and rrs genes are well known and can explain about 70% of this phenotypic resistance. Recently, the gidB gene was found to be associated with low-level streptomycin resistance in Mycobacterium tuberculosis. Mutations in gidB have been reported with high frequency, and this gene appears to be very polymorphic, with frameshift and point mutations occurring in streptomycin-susceptible and streptomycin-resistant strains. In this study, mutations in gidB appeared in 27% of streptomycin-resistant strains that contained no mutations in the rpsL or rrs genes, and they were associated with low-level streptomycin resistance. However, the association of certain mutations in gidB with streptomycin resistance needs to be further investigated, as we also found mutations in gidB in streptomycin-susceptible strains. This occurred only when the strain was resistant to rifampin and isoniazid. Two specific mutations appeared very frequently in this and other studies of streptomycin-susceptible and -resistant strains; these mutations were not considered related to streptomycin resistance, but as a polymorphism. We stratified the strains according to the different phylogenetic lineages and showed that the gidB(16) polymorphism (16G allele) was exclusively present in the Latin American-Mediterranean (LAM) genotype, while the gidB(92) polymorphism (92C allele) was associated with the Beijing lineage in another population. In the sample studied, the two characterized single-nucleotide polymorphisms could distinguish LAM and Beijing lineages from the other lineages.

  10. Acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in contacts of patients newly identified as colonized or infected with MRSA in the immediate postexposure and postdischarge periods.

    Science.gov (United States)

    Williams, Victoria R; Callery, Sandra; Vearncombe, Mary; Simor, Andrew E

    2017-03-01

    The acquisition of methicillin-resistant Staphylococcus aureus (MRSA) after exposure to patients colonized or infected with MRSA was assessed. Among contacts with complete surveillance screening, the rate of acquisition was 5.7% and was lower in those identified postdischarge (17/683, 2.5%) compared with those tested in the immediate postexposure period (62/706, 8.8%). Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  11. Modelling of Dynamic Transmission Cable Temperature Considering Soil-Specific Heat, Thermal Resistivity, and Precipitation

    DEFF Research Database (Denmark)

    Olsen, Rasmus; Anders, George J.; Holboell, Joachim

    2013-01-01

    This paper presents an algorithm for the estimation of the time-dependent temperature evolution of power cables, when real-time temperature measurements of the cable surface or a point within its vicinity are available. The thermal resistivity and specific heat of the cable surroundings are varied...

  12. Physiological studies on cultivar-specific resistance of tomato plants to Cladosporium fulvum

    NARCIS (Netherlands)

    Wit, de P.J.G.M.

    1981-01-01

    Ultrastructural and physiological aspects of cultivar-specific resistance of tomato against Cladosporium fulvum (syn. Fulvia fulva) are subject of this thesis.

    The ultrastructural study described in the first paper was meant as an introduction to a

  13. Assessing specific gravity of young Eucalyptus plantation trees using a resistance drilling technique

    Science.gov (United States)

    José Tarcísio da Silva Oliveira; Xiping Wang; Graziela Baptista Vidaurre

    2017-01-01

    The resistance drilling technique has been in focus for assessing the specific gravity (SG) of young Eucalyptus trees from plantations for pulpwood production. Namely, the data of 50 34-month-old and 50 62-monthold trees from Eucalyptus grandis × Eucalyptus urophylla clonal plantations was evaluated, while...

  14. Impact of crystal orientation on ohmic contact resistance of enhancement-mode p-GaN gate high electron mobility transistors on 200 mm silicon substrates

    Science.gov (United States)

    Van Hove, Marleen; Posthuma, Niels; Geens, Karen; Wellekens, Dirk; Li, Xiangdong; Decoutere, Stefaan

    2018-04-01

    p-GaN gate enhancement mode power transistors were processed in a Si CMOS processing line on 200 mm Si(111) substrates using Au-free metallization schemes. Si/Ti/Al/Ti/TiN ohmic contacts were formed after full recessing of the AlGaN barrier, followed by a HCl-based wet cleaning step. The electrical performance of devices aligned to the [11\\bar{2}0] and the perpendicular [1\\bar{1}00] directions was compared. The ohmic contact resistance was decreased from 1 Ω·mm for the [11\\bar{2}0] direction to 0.35 Ω·mm for the [1\\bar{1}00] direction, resulting in an increase of the drain saturation current from 0.5 to 0.6 A/mm, and a reduction of the on-resistance from 6.4 to 5.1 Ω·mm. Moreover, wafer mapping of the device characteristics over the 200 mm wafer showed a tighter statistical distribution for the [1\\bar{1}00] direction. However, by using an optimized sulfuric/ammonia peroxide (SPM/APM) cleaning step, the ohmic contact resistance could be lowered to 0.3 Ω·mm for both perpendicular directions.

  15. Contact allergy to the 26 specific fragrance ingredients to be declared on cosmetic products in accordance with the EU cosmetics directive

    DEFF Research Database (Denmark)

    Heisterberg, Maria V; Menné, Torkil; Johansen, Jeanne D

    2011-01-01

    Background. Fragrance ingredients are a frequent cause of allergic contact dermatitis. The EU Cosmetics Directive states that 26 specific fragrance ingredients, known to cause allergic contact dermatitis, must be declared on the ingredient lists of cosmetic products. Objectives. To investigate...... frequencies of sensitization to the 26 individual fragrances and evaluate their importance as screening markers of fragrance allergy. Method. This was a retrospective study based on data from the Department of Dermato-Allergology, Copenhagen University Hospital Gentofte. Eczema patients (n = 1508) were patch...

  16. Nasal carriage of methicillin-resistant coagulase-negative staphylococci in healthy humans is associated with occupational pig contact in a dose-response manner.

    Science.gov (United States)

    Li, Ling; Chen, Zhiyao; Guo, Dan; Li, Shunming; Huang, Jingya; Wang, Xiaolin; Yao, Zhenjiang; Chen, Sidong; Ye, Xiaohua

    2017-09-01

    This study aimed to explore the association between occupational pig contact and human methicillin-resistant coagulase-negative staphylococci (MRCoNS) carriage. We conducted a cross-sectional study of pig exposed participants and controls in Guangdong, China, using a multi-stage sampling design. Participants provided a nasal swab for MRCoNS analysis and resulting isolates were tested for antibiotic susceptibility. The dose-response relation was examined using log binomial regression or Poisson regression models. The adjusted prevalence of MRCoNS carriage in pig exposed participants was 1.67 times (95% CI: 1.32-2.11) higher than in controls. The adjusted average number of resistance to different antibiotic classes of MRCoNS isolates from pig exposed participants was 1.67 times (95% CI: 1.46-1.91) higher than those from controls. Notably, we found the frequency and duration of occupational pig contact was associated with increased prevalence and increased number of resistance to different antibiotic classes of MRCoNS in a dose-response manner. When examining these relations by MRCoNS species, there was still evidence of similar exposure-response relations. Additionally, the proportion of tetracycline-resistant and tet(M)-containing MRCoNS isolates was significantly higher in pig exposed participants than in controls. These findings suggested a potential transmission of MRCoNS from livestock to humans by occupational livestock contact, and the presence of phenotypic and genotypic tetracycline resistance may aid in the differentiation of animal origins of MRCoNS isolates. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Site-specific regulation of oral mucosa-recruiting CD8+T cells in a mouse contact allergy model.

    Science.gov (United States)

    Hirunwidchayarat, Worawalun; Furusawa, Emi; Kang, Siwen; Ohno, Tatsukuni; Takeuchi, Shunsuke; Rungsiyanont, Sorasun; Azuma, Miyuki

    2017-09-02

    Contact allergy is a T cell-mediated, delayed-type hypersensitivity generated by contact exposure of an allergen to the skin and mucosal surface. The clinical manifestations of allergic responses between the skin and oral mucosa vary and the differences in immunopathology have not been clarified. We generated hapten-induced contact hypersensitivity (CH) of the buccal mucosa (BM) in parallel studies with ear skin (ES) CH, and observed several characteristic findings of BM CH. The BM challenge induced more rapid and more severe inflammation than the ES challenge, with abundant granulocyte and CD8 + T cell infiltration. However, these inflammatory responses diminished quickly. Recruiting CD8 + T cells in the BM had higher ratios of CD62L - CD44 low-hi memory-type cells, and showed impaired IFN-γ, greater PD-1, and comparable Ki-67 expression, suggesting that the recruiting-proliferating CD8 + T cells were unable to differentiate into effector T cells and converted into exhausted T cells at the local site. This finding may explain the rapid recovery of the BM from severe inflammation. Preferentially greater expression of PD-1 ligand (B7-H1), was observed in the BM epithelium under the peak inflammation, and the absence of B7-H1 further accelerated CH responses, suggesting the occurrence of PD-1:B7-H1-mediated immune regulation at the local site. Our results may facilitate the understanding of the unique features of contact allergies in the oral mucosa, and guide the development of new strategies for control of contact allergy. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Quantifying variety-specific heat resistance and the potential for adaptation to climate change.

    Science.gov (United States)

    Tack, Jesse; Barkley, Andrew; Rife, Trevor W; Poland, Jesse A; Nalley, Lawton Lanier

    2016-08-01

    The impact of climate change on crop yields has become widely measured; however, the linkages for winter wheat are less studied due to dramatic weather changes during the long growing season that are difficult to model. Recent research suggests significant reductions under warming. A potential adaptation strategy involves the development of heat resistant varieties by breeders, combined with alternative variety selection by producers. However, the impact of heat on specific wheat varieties remains relatively unstudied due to limited data and the complex genetic basis of heat tolerance. Here, we provide a novel econometric approach that combines field-trial data with a genetic cluster mapping to group wheat varieties and estimate a separate extreme heat impact (temperatures over 34 °C) across 24 clusters spanning 197 varieties. We find a wide range of heterogeneous heat resistance and a trade-off between average yield and resistance. Results suggest that recently released varieties are less heat resistant than older varieties, a pattern that also holds for on-farm varieties. Currently released - but not yet adopted - varieties do not offer improved resistance relative to varieties currently grown on farm. Our findings suggest that warming impacts could be significantly reduced through advances in wheat breeding and/or adoption decisions by producers. However, current adaptation-through-adoption potential is limited under a 1 °C warming scenario as increased heat resistance cannot be achieved without a reduction in average yields. © 2015 John Wiley & Sons Ltd.

  19. Specificity and levels of nonhost resistance to nonadapted Blumeria graminis forms in barley.

    Science.gov (United States)

    Aghnoum, Reza; Niks, Rients E

    2010-01-01

    The genetic basis of nonhost resistance of barley to nonadapted formae speciales of Blumeria graminis is not known, as there is no barley line that is susceptible to these nonadapted formae speciales, such as the wheat powdery mildew pathogen, Blumeria graminis f.sp. tritici (Bgt). Barley accessions with rudimentary susceptibility to an isolate of the nonadapted Bgt were identified. Those accessions were intercrossed in two cycles and two lines, called SusBgt(SC) and SusBgt(DC), with substantial susceptibility to Bgt at the seedling stage were selected. The quantitative variation among barley accessions and in the progenies after convergent crossing suggests a polygenic basis for this nonhost resistance. Both lines allowed an unusually high level of haustorium formation and colony development by Bgt. The SusBgt lines and their ancestor lines also allowed haustorium formation and conidiation by four out of seven isolates of other nonadapted B. graminis forms. Analysis of the infection process suggested that nonhost resistance factors are specific to the form and developmental stage of B. graminis. Resistances to establishment (first haustorium), colonization (subsequent haustoria) and conidiation are not associated. The lines developed will be of use in elucidating the genetic basis of nonhost resistance to Bgt in barley, and in gene expression and complementation studies on nonhost resistance.

  20. Contact metallurgy optimization for ohmic contacts to InP

    DEFF Research Database (Denmark)

    Clausen, Thomas; Pedersen, Arne Skyggebjerg; Leistiko, Otto

    1991-01-01

    AuGeNi and AuZnNi metallizations to n- and p-InP were studied as a function of the annealing temperature in a Rapid Thermal Annealing (RTA) system. For n-InP (S:8×1018cm-3) a broad minimum existed from 385°C to 500°C, in which the specific contact resistance, rc, was about 10-7 ¿cm2. The lowe...

  1. Identification of genes involved in Pseudomonas aeruginosa biofilm-specific resistance to antibiotics.

    Directory of Open Access Journals (Sweden)

    Li Zhang

    Full Text Available Pseudomonas aeruginosa is a key opportunistic pathogen characterized by its biofilm formation ability and high-level multiple antibiotic resistance. By screening a library of random transposon insertion mutants with an increased biofilm-specifc antibiotic susceptibility, we previously identified 3 genes or operons of P. aeruginosa UCBPP-PA14 (ndvB, PA1875-1877 and tssC1 that do not affect biofilm formation but are involved in biofilm-specific antibiotic resistance. In this study, we demonstrate that PA0756-0757 (encoding a putative two-component regulatory system, PA2070 and PA5033 (encoding hypothetical proteins of unknown function display increased expression in biofilm cells and also have a role in biofilm-specific antibiotic resistance. Furthermore, deletion of each of PA0756, PA2070 and PA5033 resulted in a significant reduction of lethality in Caenorhabditis elegans, indicating a role for these genes in both biofilm-specific antibiotic resistance and persistence in vivo. Together, these data suggest that these genes are potential targets for antimicrobial agents.

  2. Identification of Genes Involved in Pseudomonas aeruginosa Biofilm-Specific Resistance to Antibiotics

    Science.gov (United States)

    Zhang, Li; Fritsch, Meredith; Hammond, Lisa; Landreville, Ryan; Slatculescu, Cristina; Colavita, Antonio; Mah, Thien-Fah

    2013-01-01

    Pseudomonas aeruginosa is a key opportunistic pathogen characterized by its biofilm formation ability and high-level multiple antibiotic resistance. By screening a library of random transposon insertion mutants with an increased biofilm-specifc antibiotic susceptibility, we previously identified 3 genes or operons of P. aeruginosa UCBPP-PA14 (ndvB, PA1875–1877 and tssC1) that do not affect biofilm formation but are involved in biofilm-specific antibiotic resistance. In this study, we demonstrate that PA0756–0757 (encoding a putative two-component regulatory system), PA2070 and PA5033 (encoding hypothetical proteins of unknown function) display increased expression in biofilm cells and also have a role in biofilm-specific antibiotic resistance. Furthermore, deletion of each of PA0756, PA2070 and PA5033 resulted in a significant reduction of lethality in Caenorhabditis elegans, indicating a role for these genes in both biofilm-specific antibiotic resistance and persistence in vivo. Together, these data suggest that these genes are potential targets for antimicrobial agents. PMID:23637868

  3. Prevalence and antimicrobial resistance of Salmonella isolated from lactating cows and in contact humans in dairy farms of Addis Ababa: a cross sectional study

    Directory of Open Access Journals (Sweden)

    Yirsaw Alehegne

    2011-08-01

    Full Text Available Abstract Background Salmonella are the major pathogenic bacteria in humans as well as in animals. Salmonella species are leading causes of acute gastroenteritis in several countries and salmonellosis remains an important public health problem worldwide, particularly in the developing countries. The situation is more aggravated by the ever increasing rate of antimicrobial resistance strains. Cattle have been implicated as a source of human infection with antimicrobial resistant Salmonella through direct contact with livestock and through the isolation of antimicrobial resistant Salmonella from raw milk, cheddar cheese, and hamburger meat traced to dairy farms. Despiite the presence of many studies on the prevalence and antimicrobial susceptibility pattern of Salmonella in Ethiopia, nothing has been said on the degree of the situation among apparently healthy lactating cows and in contact humans. Hence this study was conducted to determine the prevalence and antimicrobial resistance pattern of Salmonella isolates from lactating cows and in contact humans in dairy farms of Addis Ababa. Methods a cross sectional study was conducted in Addis Ababa by collecting milk and faecal samples from lactating cows and stool samples from humans working in dairy farms. Samples were pre-enriched in buffered peptone water followed by selective enrichment using selenite cysteine and Rapaport-Vassilidis broths. Isolation and identification was made by inoculating the selectively enriched sample on to Xylose Lysine Deoxycholate agar followed by confirmation of presumptive colonies using different biochemical tests. The Kibry Bauer disk diffusion method was used for antimicrobial sensitivity testing. Results 10.7% (21/195 of cows and 13.6% (3/22 of the human subjects sheded Salmonella. 83% resistance to two or more antimicrobials and 100% resistance to ampicillin were observed. Most of the isolates were relatively sensitive to ciprofloxacin, cotrimoxazole, and

  4. Attachment and Interpersonal Specifics if Well-Being in Relation to Employee Job Performance of Contact Centres

    OpenAIRE

    Ivana Tomanová Čergeťová; Lucia Bošiaková

    2015-01-01

    The research is focused on exploring of multiple relations between interpersonal and attachment characteristics, job performance, job satisfaction and well-being of employees in contact centres. Global assessment of well-being represents cognitive and emotional approach of one ́s life as a whole. However, global view can be deformed by distorted perception of reality, so therefore it is necessary to evaluate well-being not only in general, ...

  5. Geophysical Characterization of the Quaternary-Cretaceous Contact Using Surface Resistivity Methods in Franklin and Webster Counties, South-Central Nebraska

    Science.gov (United States)

    Teeple, Andrew; Kress, Wade H.; Cannia, James C.; Ball, Lyndsay B.

    2009-01-01

    Formation made accurate interpretation of the resistivity profile sections difficult and less confident because of similar resistivity of this formation and that of the coarser-grained sediment of the Quaternary-age deposits. However, distinct conductive features were identified within the resistivity profile sections that aided in delineating the contact between the resistive Quaternary-age deposits and the resistive Niobrara Formation. Using this information, an interpretive boundary was drawn on the resistivity profile sections to represent the contact between the Quaternary-age alluvial deposits and the Cretaceous-age Niobrara Formation. A digital elevation model (DEM) of the top of the Niobrara Formation was constructed using the altitudes from the interpreted contact lines. This DEM showed that the general trend of top of the Niobrara Formation dips to the southeast. At the north edge of the study site, the Niobrara Formation topographic high trends east-west with an altitude range of 559 meters in the west to 543 meters in the east. Based on the land-surface elevation and the Niobrara Formation DEM, the estimated thickness of the Quaternary-age alluvial deposits throughout the study area was mapped and showed a thinning of the Quaternary-age alluvial deposits to the north, approximately where the topographic high of the Niobrara Formation is located. This topographic high in the Niobrara Formation has the potential to act as a barrier to ground-water flow from the uplands alluvial aquifer to the Republican River alluvial aquifer as shown in the resistivity profile sections. The Quaternary-age alluvial deposits in the uplands and those in the Republican River Valley are not fully represented as disconnected because it is possible that there are ground-water flow paths that were not mapped during this study.

  6. O-specific polysaccharide confers lysozyme resistance to extraintestinal pathogenic Escherichia coli.

    Science.gov (United States)

    Bao, Yinli; Zhang, Haobo; Huang, Xinxin; Ma, Jiale; Logue, Catherine M; Nolan, Lisa K; Li, Ganwu

    2018-12-31

    Extraintestinal pathogenic Escherichia coli (ExPEC) is the leading cause of bloodstream and other extraintestinal infections in human and animals. The greatest challenge encountered by ExPEC during an infection is posed by the host defense mechanisms, including lysozyme. ExPEC have developed diverse strategies to overcome this challenge. The aim of this study was to characterize the molecular mechanism of ExPEC resistance to lysozyme. For this, 15,000 transposon mutants of a lysozyme-resistant ExPEC strain NMEC38 were screened; 20 genes were identified as involved in ExPEC resistance to lysozyme-of which five were located in the gene cluster between galF and gnd, and were further confirmed to be involved in O-specific polysaccharide biosynthesis. The O-specific polysaccharide was able to inhibit the hydrolytic activity of lysozyme; it was also required by the complete lipopolysaccharide (LPS)-mediated protection of ExPEC against the bactericidal activity of lysozyme. The O-specific polysaccharide was further shown to be able to directly interact with lysozyme. Furthermore, LPS from ExPEC strains of different O serotypes was also able to inhibit the hydrolytic activity of lysozyme. Because of their cell surface localization and wide distribution in Gram-negative bacteria, O-specific polysaccharides appear to play a long-overlooked role in protecting bacteria against exogenous lysozyme.

  7. Silencing Agrobacterium oncogenes in transgenic grapevine results in strain-specific crown gall resistance.

    Science.gov (United States)

    Galambos, A; Zok, A; Kuczmog, A; Oláh, R; Putnoky, P; Ream, W; Szegedi, E

    2013-11-01

    Grapevine rootstock transformed with an Agrobacterium oncogene-silencing transgene was resistant to certain Agrobacterium strains but sensitive to others. Thus, genetic diversity of Agrobacterium oncogenes may limit engineering crown gall resistance. Crown gall disease of grapevine induced by Agrobacterium vitis or Agrobacterium tumefaciens causes serious economic losses in viticulture. To establish crown gall-resistant lines, somatic proembryos of Vitis berlandieri × V. rupestris cv. 'Richter 110' rootstock were transformed with an oncogene-silencing transgene based on iaaM and ipt oncogene sequences from octopine-type, tumor-inducing (Ti) plasmid pTiA6. Twenty-one transgenic lines were selected, and their transgenic nature was confirmed by polymerase chain reaction (PCR). These lines were inoculated with two A. tumefaciens and three A. vitis strains. Eight lines showed resistance to octopine-type A. tumefaciens A348. Resistance correlated with the expression of the silencing genes. However, oncogene silencing was mostly sequence specific because these lines did not abolish tumorigenesis by A. vitis strains or nopaline-type A. tumefaciens C58.

  8. Specific features in the behavior of electrical resistivity of the pine biocarbon preform/copper composite

    Science.gov (United States)

    Burkov, A. T.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Jezowski, A.

    2010-11-01

    The electrical resistivity ρ( T) of the novel type of composites prepared by infiltrating melted copper in vacuum in empty sap channels of white pine high-porosity biocarbon preforms has been measured in the temperature range 5-300 K. Biocarbon preforms have been prepared by pyrolysis of tree wood in an argon flow at two carbonization temperatures, 1000 and 2400°C. The electrical resistivity of the composites has been found to vary relatively weakly with temperature and to pass through a characteristic minimum near 40-50 K, which can be ascribed to iron and manganese impurities penetrating into copper from the carbon preform when liquid copper is infiltrated into it. It has been shown that the electrical resistivity ρ( T) of the composites is governed primarily by the specific microstructure of the preform, which is made up of parallel channels with an average diameter of about 50 μm interrupted by systems of thin capillaries. The small cross section of the copper-filled capillaries accounts for these regions providing the major contribution to the electrical resistivity of the composites. An increase in the wood carbonization temperature brings about a noticeable increase in the effective capillary cross section and a decrease in the electrical resistivity ρ( T) of the composite.

  9. Specific Cell Targeting Therapy Bypasses Drug Resistance Mechanisms in African Trypanosomiasis.

    Directory of Open Access Journals (Sweden)

    Juan D Unciti-Broceta

    2015-06-01

    Full Text Available African trypanosomiasis is a deadly neglected disease caused by the extracellular parasite Trypanosoma brucei. Current therapies are characterized by high drug toxicity and increasing drug resistance mainly associated with loss-of-function mutations in the transporters involved in drug import. The introduction of new antiparasitic drugs into therapeutic use is a slow and expensive process. In contrast, specific targeting of existing drugs could represent a more rapid and cost-effective approach for neglected disease treatment, impacting through reduced systemic toxicity and circumventing resistance acquired through impaired compound uptake. We have generated nanoparticles of chitosan loaded with the trypanocidal drug pentamidine and coated by a single domain nanobody that specifically targets the surface of African trypanosomes. Once loaded into this nanocarrier, pentamidine enters trypanosomes through endocytosis instead of via classical cell surface transporters. The curative dose of pentamidine-loaded nanobody-chitosan nanoparticles was 100-fold lower than pentamidine alone in a murine model of acute African trypanosomiasis. Crucially, this new formulation displayed undiminished in vitro and in vivo activity against a trypanosome cell line resistant to pentamidine as a result of mutations in the surface transporter aquaglyceroporin 2. We conclude that this new drug delivery system increases drug efficacy and has the ability to overcome resistance to some anti-protozoal drugs.

  10. AcrB drug-binding pocket substitution confers clinically relevant resistance and altered substrate specificity.

    Science.gov (United States)

    Blair, Jessica M A; Bavro, Vassiliy N; Ricci, Vito; Modi, Niraj; Cacciotto, Pierpaolo; Kleinekathӧfer, Ulrich; Ruggerone, Paolo; Vargiu, Attilio V; Baylay, Alison J; Smith, Helen E; Brandon, Yvonne; Galloway, David; Piddock, Laura J V

    2015-03-17

    The incidence of multidrug-resistant bacterial infections is increasing globally and the need to understand the underlying mechanisms is paramount to discover new therapeutics. The efflux pumps of Gram-negative bacteria have a broad substrate range and transport antibiotics out of the bacterium, conferring intrinsic multidrug resistance (MDR). The genomes of pre- and posttherapy MDR clinical isolates of Salmonella Typhimurium from a patient that failed antibacterial therapy and died were sequenced. In the posttherapy isolate we identified a novel G288D substitution in AcrB, the resistance-nodulation division transporter in the AcrAB-TolC tripartite MDR efflux pump system. Computational structural analysis suggested that G288D in AcrB heavily affects the structure, dynamics, and hydration properties of the distal binding pocket altering specificity for antibacterial drugs. Consistent with this hypothesis, recreation of the mutation in standard Escherichia coli and Salmonella strains showed that G288D AcrB altered substrate specificity, conferring decreased susceptibility to the fluoroquinolone antibiotic ciprofloxacin by increased efflux. At the same time, the substitution increased susceptibility to other drugs by decreased efflux. Information about drug transport is vital for the discovery of new antibacterials; the finding that one amino acid change can cause resistance to some drugs, while conferring increased susceptibility to others, could provide a basis for new drug development and treatment strategies.

  11. Measurement of the specific airway resistance by plethysmography in young children accompanied by an adult

    DEFF Research Database (Denmark)

    Klug, B; Bisgaard, H

    1997-01-01

    The purpose of this study was to evaluate a procedure for measurement of specific airway resistance (sRaw) by whole body plethysmography in young awake children accompanied by an adult. sRaw was measured by a single-step procedure, omitting the measurement of the thoracic gas volume. The frequency.......8) yrs), for whom measurements made only in the presence of an accompanying adult, the CV was 8.5%. No measurements could be obtained in 22 children (17%) (mean age 2.8 (0.5) yrs). Measurements exhibited a significant frequency dependency, and electronic BTPS compensation substantially overestimated SRaw....... In conclusion, the use of electronic compensation for simulating body temperature, atmospheric pressure and saturation with water vapour introduces a bias that affects the accuracy of the estimate of specific airway resistance. Nevertheless, plethysmographic measurements with and without an accompanying adult...

  12. Time-wise change in neck pain in response to rehabilitation with specific resistance training

    DEFF Research Database (Denmark)

    Zebis, Mette Kreutzfeldt; Andersen, Christoffer H; Sundstrup, Emil

    2014-01-01

    Purpose To determine the time-wise effect of specific resistance training on neck pain among industrial technicians with frequent neck pain symptoms. Methods Secondary analysis of a parallel-group cluster randomized controlled trial of 20 weeks performed at two large industrial production units...... in Copenhagen, Denmark. Women with neck pain >30 mm VAS (N = 131) were included in the present analysis. The training group (N = 77) performed specific resistance training for the neck/shoulder muscles three times a week, and the control group (N = 54) received advice to stay active. Participants of both groups...... to 20). The time-wise change in pain showed three phases; a rapid decrease in the training group compared with the control group during the initial 7 weeks, a slower decrease in pain during the following weeks (week 8–15), and a plateau during the last weeks (week 16–20). Adherence to training followed...

  13. Measurement of the specific airway resistance by plethysmography in young children accompanied by an adult

    DEFF Research Database (Denmark)

    Klug, B; Bisgaard, H

    1997-01-01

    dependency of sRaw was investigated and the accuracy of simulating body temperature, atmospheric pressure and saturation with water vapour (BTPS) conditions by electronic compensation was assessed. One hundred and thirty one children with asthma were studied. In 57 children (mean (SD) age 5.6 (1.8) yrs) who....... In conclusion, the use of electronic compensation for simulating body temperature, atmospheric pressure and saturation with water vapour introduces a bias that affects the accuracy of the estimate of specific airway resistance. Nevertheless, plethysmographic measurements with and without an accompanying adult......The purpose of this study was to evaluate a procedure for measurement of specific airway resistance (sRaw) by whole body plethysmography in young awake children accompanied by an adult. sRaw was measured by a single-step procedure, omitting the measurement of the thoracic gas volume. The frequency...

  14. Electrical Resistance Measurements and Microstructural Characterization of the Anode/Interconnect Contact in Simulated Anode-Side SOFC Conditions

    DEFF Research Database (Denmark)

    Harthøj, Anders; Alimadadi, Hossein; Holt, Tobias

    2015-01-01

    . The zone is austenitic at the exposure temperature but transforms to ferrite during cooling. When a CeO2 nickel diffusion barrier layer was used The ASR was considerably higher. These results imply that nickel diffusion is not only detrimental: It leads to microstructural instability but also results......Metallic interconnects in solid oxide fuel cell (SOFC) stacks are often in direct contact with a nickel/yttria stabilized zirconia (Ni/YSZ) cermet anode. Interdiffusion between the two components may occur at the operating temperature of 700–850◦C. The alteration of chemical composition can result...... anode conditions at 800◦C. The microstructure in the contact area was characterized using scanning electron microscopy techniques. The ASR was low for the steel in direct contact with the Ni/YSZ anode. Nickel diffusion into the steel resulted in a fine grained zone, which was identified as ferrite...

  15. Evidence of isolate-specificity in non-hypersensitive resistance in spring wheat (Triticum aestivum) to wheat leaf rust

    NARCIS (Netherlands)

    Qamar, Maqsood; Niks, R.E.

    2007-01-01

    Isolate-specific aspect of non-hypersensitive resistance in wheat to wheat leaf rust was studied at seedling stage in the green house. Isolate-specific response of non-hypersensitive resistance was assessed from latency period (LP) and infection frequency (IF) of two single-pustule isolates of

  16. Genetic parameters for pathogen-specific mastitis resistance in Danish Holstein cattle

    DEFF Research Database (Denmark)

    Sørensen, Lars Peter; Madsen, P.; Mark, Thomas

    2009-01-01

    as the overall pleiotropic effect of genes affecting resistance to a specific pathogen, and highest for bacteria sharing characteritics regarding immune response. The genetic correlations between the groups of pathogens were high, 0.73 and 0.83. Results showed that the pathogen-specific traits used in this study...... general is critical for a successful genetic evaluation of udder health. Also, economic values have to be specified for each pathogen-specific trait separately.......The objective of this study was to estimate heritabilities for and genetic correlations among different pathogen-specific mastitis traits. The traits were unspecific mastitis, which is all mastitis treatments regardless of the causative pathogen as well as mastitis caused by Streptococcus...

  17. Sunflower Resistance to Broomrape (Orobanche cumana) Is Controlled by Specific QTLs for Different Parasitism Stages.

    Science.gov (United States)

    Louarn, Johann; Boniface, Marie-Claude; Pouilly, Nicolas; Velasco, Leonardo; Pérez-Vich, Begoña; Vincourt, Patrick; Muños, Stéphane

    2016-01-01

    Orobanche cumana (sunflower broomrape) is an obligatory and non-photosynthetic root parasitic plant that specifically infects the sunflower. It is located in Europe and in Asia, where it can cause yield losses of over 80%. More aggressive races have evolved, mainly around the Black Sea, and broomrape can rapidly spread to new areas. Breeding for resistance seems to be the most efficient and sustainable approach to control broomrape infestation. In our study, we used a population of 101 recombinant inbred lines (RILs), derived from a cross between the two lines HA89 and LR1 (a line derived from an interspecific cross with Helianthus debilis). Rhizotrons, pots and field experiments were used to characterize all RILs for their resistance to O. cumana race F parasitism at three post vascular connection life stages: (i) early attachment of the parasite to the sunflower roots, (ii) young tubercle and (iii) shoot emergence. In addition, RIL resistance to race G at young tubercle development stage was evaluated in pots. The entire population was genotyped, and QTLs were mapped. Different QTLs were identified for each race (F from Spain and G from Turkey) and for the three stages of broomrape development. The results indicate that there are several quantitative resistance mechanisms controlling the infection by O. cumana that can be used in sunflower breeding.

  18. Sunflower resistance to broomrape (Orobanche cumana is controlled by specific QTLs for different parasitism stages

    Directory of Open Access Journals (Sweden)

    Johann eLouarn

    2016-05-01

    Full Text Available Orobanche cumana (sunflower broomrape is an obligatory and non-photosynthetic root parasitic plant that specifically infects the sunflower. It is located in Europe and in Asia, where it can cause yield losses of over 80%. More aggressive races have evolved, mainly around the Black Sea, and broomrape can rapidly spread to new areas. Breeding for resistance seems to be the most efficient and sustainable approach to control broomrape infestation.In our study, we used a population of 101 recombinant inbred lines (RILs, derived from a cross between the two lines HA89 and LR1 (a line derived from an interspecific cross with H. debilis. Rhizotrons, pots and field experiments were used to characterize all RILs for their resistance to O. cumana race F parasitism at three post vascular connection life stages: (i early attachment of the parasite to the sunflower roots, (ii young tubercle and (iii shoot emergence. In addition, RIL resistance to race G at young tubercle development stage was evaluated in pots. The entire population was genotyped, and QTLs were mapped. Different QTLs were identified for each race (F from Spain and G from Turkey and for the three stages of broomrape development.The results indicate that there are several quantitative resistance mechanisms controlling the infection by O. cumana that can be used in sunflower breeding.

  19. Sunflower Resistance to Broomrape (Orobanche cumana) Is Controlled by Specific QTLs for Different Parasitism Stages

    Science.gov (United States)

    Louarn, Johann; Boniface, Marie-Claude; Pouilly, Nicolas; Velasco, Leonardo; Pérez-Vich, Begoña; Vincourt, Patrick; Muños, Stéphane

    2016-01-01

    Orobanche cumana (sunflower broomrape) is an obligatory and non-photosynthetic root parasitic plant that specifically infects the sunflower. It is located in Europe and in Asia, where it can cause yield losses of over 80%. More aggressive races have evolved, mainly around the Black Sea, and broomrape can rapidly spread to new areas. Breeding for resistance seems to be the most efficient and sustainable approach to control broomrape infestation. In our study, we used a population of 101 recombinant inbred lines (RILs), derived from a cross between the two lines HA89 and LR1 (a line derived from an interspecific cross with Helianthus debilis). Rhizotrons, pots and field experiments were used to characterize all RILs for their resistance to O. cumana race F parasitism at three post vascular connection life stages: (i) early attachment of the parasite to the sunflower roots, (ii) young tubercle and (iii) shoot emergence. In addition, RIL resistance to race G at young tubercle development stage was evaluated in pots. The entire population was genotyped, and QTLs were mapped. Different QTLs were identified for each race (F from Spain and G from Turkey) and for the three stages of broomrape development. The results indicate that there are several quantitative resistance mechanisms controlling the infection by O. cumana that can be used in sunflower breeding. PMID:27242810

  20. Assessment of genetic variation for pathogen-specific mastitis resistance in Valle del Belice dairy sheep.

    Science.gov (United States)

    Tolone, Marco; Larrondo, Cristian; Yáñez, José M; Newman, Scott; Sardina, Maria Teresa; Portolano, Baldassare

    2016-07-28

    Mastitis resistance is a complex and multifactorial trait, and its expression depends on both genetic and environmental factors, including infection pressure. The objective of this research was to determine the genetic basis of mastitis resistance to specific pathogens using a repeatability threshold probit animal model. The most prevalent isolated pathogens were coagulase-negative staphylococci (CNS); 39 % of records and 77 % of the animals infected at least one time in the whole period of study. There was significant genetic variation only for Streptococci (STR). In addition, there was a positive genetic correlation between STR and all pathogens together (ALL) (0.36 ± 0.22), and CNS and ALL (0.92 ± 0.04). The results of our study support the presence of significant genetic variation for mastitis caused by Streptococci and suggest the importance of discriminating between different pathogens causing mastitis due to the fact that they most likely influence different genetic traits. Low heritabilities for pathogen specific-mastitis resistance may be considered when including bacteriological status as a measure of mastitis presence to implement breeding strategies for improving udder health in dairy ewes.

  1. Contact Lens Risks

    Science.gov (United States)

    ... Tap and distilled water have been associated with Acanthamoeba keratitis, a corneal infection that is resistant to ... to: Advice for Patients With Soft Contact Lenses: Acanthamoeba Keratitis Infections Related to Complete® MoisturePlus Multi Purpose ...

  2. Contact allergy to the 26 specific fragrance ingredients to be declared on cosmetic products in accordance with the EU cosmetics directive

    DEFF Research Database (Denmark)

    Heisterberg, Maria V; Menné, Torkil; Johansen, Jeanne D

    2011-01-01

    Background. Fragrance ingredients are a frequent cause of allergic contact dermatitis. The EU Cosmetics Directive states that 26 specific fragrance ingredients, known to cause allergic contact dermatitis, must be declared on the ingredient lists of cosmetic products. Objectives. To investigate...... frequencies of sensitization to the 26 individual fragrances and evaluate their importance as screening markers of fragrance allergy. Method. This was a retrospective study based on data from the Department of Dermato-Allergology, Copenhagen University Hospital Gentofte. Eczema patients (n = 1508) were patch......). Including fragrance mix I, fragrance mix II and Myroxylon pereirae, 196 (13.0%) had a fragrance allergy. Testing with the 26 fragrances additionally identified 23 subjects who would otherwise have gone undetected. The majority (75.7%) of positive reactions to the 26 fragrances were of clinical relevance...

  3. Attachment and Interpersonal Specifics if Well-Being in Relation to Employee Job Performance of Contact Centres

    Directory of Open Access Journals (Sweden)

    Ivana Tomanová Čergeťová

    2015-01-01

    Full Text Available The research is focused on exploring of multiple relations between interpersonal and attachment characteristics, job performance, job satisfaction and well-being of employees in contact centres. Global assessment of well-being represents cognitive and emotional approach of one ́s life as a whole. However, global view can be deformed by distorted perception of reality, so therefore it is necessary to evaluate well-being not only in general, but also as many different aspects of human life. This study is focused on working environment as one of thesignificant parts of life. Our sample consisted of 176 employees of contact centres, 116 of them were women (65,91% and 60 men (34,09%. The age range was from 21 to 56 years (average –29,78 years. The average length of employment of a telephone operator was 14 months. The major part of workforce were workers in permanent employment – 54,55% (N = 96, performance contract employees – 40,91% (N = 72, students employed based on agreement on temporary job of student – 3,41% (N = 6 and freelancers / self-employed – 1,14% (N = 2. The quantitative and qualitative data were obtained using standardised questionnaires. A short form of Egna Minnen Beträffande Uppfostran (s-E.M.B.U.; Willem et al., 1999, which is bas ed on Bowlby attachment theory, was used to measure attachment style. The interpersonal characteristics were measured by Interpersonal Check List (ICL; Kožený & Ganický, 1976. The job performance was measured by means of a call centre software system called Aheeva CCS Manager. Other questionnaires were focused on job satisfaction and well-being. The evaluation of job satisfaction was realised by means of Minnesota Satisfaction Questionnaire (MSQ; Weiss et al., 1967 and well-being was measured by means of two questionnaires - Satisfaction with Life Scale (SWLS; Diener, Emmons, Larsen, & Griffin, 1985 and Scales of Psychological Well-Being (SPWB; Ryff, 1989. The results of this study

  4. The importance of the neutral region resistance for the calculation of the interface state in Pb/p-Si Schottky contacts

    International Nuclear Information System (INIS)

    Aydin, M.E.; Akkilic, K.; Kilicoglu, T.

    2004-01-01

    We have fabricated H-terminated Pb/p-type Si Schottky contacts with and without the native oxide layer to explain the importance of the fact that the neutral region resistance value is considered in calculating the interface state density distribution from the nonideal forward bias current-voltage (I-V) characteristics. The diodes with the native oxide layer (metal-insulating layer-semiconductor (MIS)) showed nonideal I-V behavior with an ideality factor value of 1.310 and the barrier height value of 0.746eV. An ideality factor value of 1.065 and a barrier height value of 0.743eV were obtained for the diodes without the native oxide layer (MS). At the same energy position near the top of the valance band, the calculated interface states density (Nss) values, obtained without taking into account the series resistance of the devices (i.e. without subtracting the voltage drop across the series resistance from the applied voltage values V) is almost one order of magnitude larger than Nss values obtained by taking into account the series resistance

  5. Contact and fumigant toxicity of Cyperus rotundus steam distillate constituents and related compounds to insecticide-susceptible and -resistant Blattella germanica.

    Science.gov (United States)

    Chang, Kyu-Sik; Shin, E-Hyun; Park, Chan; Ahn, Young-Joon

    2012-05-01

    We assessed the toxicity of 17 steam distillate constituents of Cyperus rotundus (L.) rhizome, another seven known compounds of C. rotundus rhizome, and 14 structurally related compounds to females from an insecticide-susceptible KSS strain and two field-collected SEL and DJN colonies of Blattella germanica (L.). High contact + fumigant toxicity to KSS females was produced by p-cymene, nerol, linalool, o-cymene, (S)-(-)-citronellal, (1S)-(-)-camphor, terpinolene, and m-cymene (LD50, 0.29-0.47 mg/cm2). The toxicity of these compounds was virtually identical against females from any of the three strains, even though SEL and DJN females were resistant to six acetylcholinesterase inhibitors and three pyrethroids (resistance ratio, 9-154 and 12-195). These results indicate that the compounds and insecticides do not share a common mode of action or elicit cross-resistance. The test compounds were effective in closed but not in open containers against SEL females, indicating that their route of insecticidal action was largely a result of vapor action. Structure-activity relationship indicates that structural characteristics, such as types of functional groups, appear to play a role in determining the terpenoid toxicities to B. germanica. C. rotundus rhizome steam distillate constituents and related compounds described merit further study as potential fumigants for the control of resistant cockroach populations in light of global efforts to reduce the level of highly toxic synthetic insecticides in indoor environments.

  6. Assessment of altered binding specificity of bacteriophage for ciprofloxacin-induced antibiotic-resistant Salmonella Typhimurium.

    Science.gov (United States)

    Kim, Jeongjin; Jo, Ara; Ding, Tian; Lee, Hyeon-Yong; Ahn, Juhee

    2016-08-01

    This study describes a new effort toward understanding the interaction mechanisms between antibiotic-resistant Salmonella Typhimurium and phages. The antibiotic susceptibility, β-lactamase activity, bacterial motility, gene expression, and lytic activity were evaluated in ciprofloxacin-induced antibiotic-sensitive Salmonella Typhimurium (ASST(CIP)) and ciprofloxacin-induced antibiotic-resistant S. Typhimurium (ARST(CIP)), which were compared to the wild-type strains (ASST(WT) and ARST(WT)). The MIC values of ampicillin, norfloxacin, chloramphenicol, and tetracycline were significantly increased to > 512, 16, 16, and 256 μg/ml, respectively, in the ARST(CIP). The lowest and highest extracellular lactamase activities were observed in ASST(WT) (6.85 μmol/min/ml) and ARST(CIP) (48.83 μmol/min/ml), respectively. The acrA, lpfE, and hilA genes were significantly upregulated by more than tenfold in both ASST(CIP) and ARST(CIP). The induction of multiple antibiotic resistance resulted from the increased efflux pump activity (AcrAB-TolC). The highest phage adsorption rates were more than 95 % for ASST(WT), ASST(CIP), and ARST(WT), while the lowest adsorption rate was 52 % for ARST(CIP) at 15 min of infection. The least lytic activity of phage was 20 % against the ARST(CIP), followed by ASST(CIP) (30 %). The adsorption rate of phage against ARST(CIP) was 52 % at 15 min of infection, which resulted in the decrease in lytic activity (12 %). Understanding the interaction of phage and bacteria is essential for the practical application of phage to control and detect antibiotic-resistant bacteria. The results provide useful information for understanding the binding specificity of phages for multiple antibiotic-resistant pathogens.

  7. Analysis of Clinical HIV-1 Strains with Resistance to Maraviroc Reveals Strain-Specific Resistance Mutations, Variable Degrees of Resistance, and Minimal Cross-Resistance to Other CCR5 Antagonists.

    Science.gov (United States)

    Flynn, Jacqueline K; Ellenberg, Paula; Duncan, Renee; Ellett, Anne; Zhou, Jingling; Sterjovski, Jasminka; Cashin, Kieran; Borm, Katharina; Gray, Lachlan R; Lewis, Marilyn; Jubb, Becky; Westby, Mike; Lee, Benhur; Lewin, Sharon R; Churchill, Melissa; Roche, Michael; Gorry, Paul R

    2017-12-01

    Maraviroc (MVC) is an allosteric inhibitor of human immunodeficiency virus type 1 (HIV-1) entry, and is the only CCR5 antagonist licensed for use as an anti-HIV-1 therapeutic. It acts by altering the conformation of the CCR5 extracellular loops, rendering CCR5 unrecognizable by the HIV-1 envelope (Env) glycoproteins. This study aimed to understand the mechanisms underlying the development of MVC resistance in HIV-1-infected patients. To do this, we obtained longitudinal plasma samples from eight subjects who experienced treatment failure with phenotypically verified, CCR5-tropic MVC resistance. We then cloned and characterized HIV-1 Envs (n = 77) from plasma of pretreatment (n = 36) and treatment failure (n = 41) samples. Our results showed variation in the magnitude of MVC resistance as measured by reductions in maximal percent inhibition of Env-pseudotyped viruses, which was more pronounced in 293-Affinofile cells compared to other cells with similar levels of CCR5 expression. Amino acid determinants of MVC resistance localized to the V3 Env region and were strain specific. We also observed minimal cross-resistance to other CCR5 antagonists by MVC-resistant strains. We conclude that 293-Affinofile cells are highly sensitive for detecting and measuring MVC resistance through a mechanism that is CCR5-dependent yet independent of CCR5 expression levels. The strain-specific nature of resistance mutations suggests that sequence-based diagnostics and prognostics will need to be more sophisticated than simple position scoring to be useful for managing resistance in subjects taking MVC. Finally, the minimal levels of cross-resistance suggests that recognition of the MVC-modified form of CCR5 does not necessarily lead to recognition of other antagonist-modified forms of CCR5.

  8. Mechanical Contact Experiments and Simulations

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Martins, P; Zhang, W.

    2011-01-01

    . The overall investigation serves for testing and validating the numerical implementation of the mechanical contact, which is one of the main contributions to a system intended for 3D simulation of resistance welding. Correct modelling of contact between parts to be welded, as well as contact with electrodes...... geometries and different materials are analyzed including contact between dissimilar materials. The numerical implementation is performed with a finite element computer program based on the irreducible flow formulation, and contact between deformable objects is modelled by applying the penalty method......, is crucial for satisfactory modelling of the resistance welding process. The resistance heating at the contact interfaces depends on both contact area and pressure, and as the contact areas develop dynamically, the presented tests are relevant for assessing the validity and accuracy of the mechanical contact...

  9. Mechanical Contact Experiments and Simulations

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Martins, P; Zhang, W.

    2011-01-01

    Mechanical contact is studied under dynamic development by means of a combined numerical and experimental investigation. The experiments are designed to allow dynamical development of non-planar contact areas with significant expansion in all three directions as the load is increased. Different....... The overall investigation serves for testing and validating the numerical implementation of the mechanical contact, which is one of the main contributions to a system intended for 3D simulation of resistance welding. Correct modelling of contact between parts to be welded, as well as contact with electrodes......, is crucial for satisfactory modelling of the resistance welding process. The resistance heating at the contact interfaces depends on both contact area and pressure, and as the contact areas develop dynamically, the presented tests are relevant for assessing the validity and accuracy of the mechanical contact...

  10. Tuberculosis contact investigation with a new, specific blood test in a low-incidence population containing a high proportion of BCG-vaccinated persons

    Directory of Open Access Journals (Sweden)

    Meywald-Walter K

    2006-05-01

    Full Text Available Abstract Background BCG-vaccination can confound tuberculin skin test (TST reactions in the diagnosis of latent tuberculosis infection. Methods We compared the TST with a Mycobacterium tuberculosis specific whole blood interferon-gamma assay (QuantiFERON®-TB-Gold In Tube; QFT-G during ongoing investigations among close contacts of sputum smear positive source cases in Hamburg, Germany. Results During a 6-month period, 309 contacts (mean age 28.5 ± 10.5 years from a total of 15 source cases underwent both TST and QFT-G testing. Of those, 157 (50.8% had received BCG vaccination and 84 (27.2% had migrated to Germany from a total of 25 different high prevalence countries (i.e. >20 cases/100,000. For the TST, the positive response rate was 44.3% (137/309, whilst only 31 (10% showed a positive QFT-G result. The overall agreement between the TST and the QFT-G was low (κ = 0.2, with 95% CI 0.14.-0.23, and positive TST reactions were closely associated with prior BCG vaccination (OR 24.7; 95% CI 11.7–52.5. In contrast, there was good agreement between TST and QFT-G in non-vaccinated persons (κ = 0.58, with 95% CI 0.4–0.68, increasing to 0.68 (95% CI 0.46–0.81, if a 10-mm cut off for the TST was used instead of the standard 5 mm recommended in Germany. Conclusion The QFT-G assay was unaffected by BCG vaccination status, unlike the TST. In close contacts who were BCG-vaccinated, the QFT-G assay appeared to be a more specific indicator of latent tuberculosis infection than the TST, and similarly sensitive in unvaccinated contacts. In BCG-vaccinated close contacts, measurement of IFN-gamma responses of lymphocytes stimulated with M. tuberculosis-specific antigen should be recommended as a basis for the decision on whether to perform subsequent chest X-ray examinations or to start treatment for latent tuberculosis infection.

  11. Effect of CeO{sub 2} addition on thermal shock resistance of WC–12%Co coating deposited on ductile iron by electric contact surface strengthening

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiaoben [College of Mechanical Engineering, Donghua University, Shanghai 201620 (China); College of Mechanical Engineering, Shanghai Dianji University, Shanghai 200240 (China); Zhu, Shigen, E-mail: sgzhu@dhu.edu.cn [College of Mechanical Engineering, Donghua University, Shanghai 201620 (China); Engineering Research Center of Advanced Textile Machinery, Ministry of Education, Shanghai 201620 (China)

    2015-09-15

    Highlights: • WC–Co powders with CeO{sub 2} were deposited by electric contact strengthening (ECS). • ECS is based on electric resistive heating between the electrode and work piece. • WC–Co coating with CeO{sub 2} by ECS was metallurgically bonded to the substrate. • The addition of CeO{sub 2} could refine the coating microstructure and increase the microhardness. • By the proper addition of cerium oxide, the thermal shock performance was enhanced. - Abstract: The WC–12%Co powders with different contents of CeO{sub 2} (0.1–2 wt.%) were deposited on ductile iron by electric contact surface strengthening. The coatings with and without CeO{sub 2} were examined and tested for microstructural characteristic, phase structure, microhardness and thermal shock resistance. The comparison concluded that the proper addition of CeO{sub 2} could refine the microstructure of coatings and increase the microhardness of the coatings. By the small amount addition of cerium oxide (0.5 wt.%), the solid solution strengthening effect and grain boundaries strengthening effect would delay the time of crack formation and propagation in the coatings and enhance the thermal shock performance.

  12. Determination of the series resistance under the Schottky contacts of AlGaN/AlN/GaN Schottky barrier diodes

    International Nuclear Information System (INIS)

    Cao Zhi-Fang; Lin Zhao-Jun; Lü Yuan-Jie; Luan Chong-Biao; Yu Ying-Xia; Chen Hong; Wang Zhan-Guo

    2012-01-01

    Rectangular AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) were fabricated, and the gate and the source of the HFETs consisted of AlGaN/AlN/GaN Schottky barrier diodes (SBDs). Based on the measured forward current-voltage and the capacitance-voltage characteristics of the AlGaN/AlN/GaN SBDs, the series resistance under the Schottky contacts (R S ) was calculated using the method of power consumption, which has been proved to be valid. Finally, the method of power consumption for calculating R S was successfully used to study the two-dimensional electron gas electron mobility for a series of circular AlGaN/AlN/GaN SBDs. It is shown that the series resistance under the Schottky contacts cannot be neglected and is important for analysing and characterizing the AlGaN/AlN/GaN SBDs and the AlGaN/AlN/GaN HFETs. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. Optimization of the contact resistance in the interface structure of n-type Al/a-SiC:H by thermal annealing for optoelectronics applications

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosio, Roberto; Mireles, Jose Jr. [Technology and Engineering Institute, Ciudad Juarez University UACJ, Av. Del Charro 450N, 32310, Chihuahua (Mexico); Torres, Alfonso; Zuniga, Carlos; Moreno, Mario [National Institute for Astrophysics Optics and Electronics INAOE, Luis E. Erro 1, PO Box 51 and 216, 7200, Puebla (Mexico)

    2010-07-15

    The presented work meets the requirements for integration of amorphous silicon carbon films with silicon technology in order to obtain a complete optoelectronic system such as light emitting diodes and its electronic readout circuits. The key enabler for this integration scheme is the low temperature of deposition of a-SiC:H films and an ohmic behavior in the interface metal/a-SiC:H. In this work, the optimization of the interface Al/a-SiC:H films are performed by means of thermal annealing timing. The a-SiC:H films were deposited by enhanced chemical vapor deposition from CH{sub 4}/SiH{sub 4} and C{sub 2}H{sub 2}/SiH{sub 4} mixtures. The structural and optical properties of the deposited films are presented. An implantation phosphorous dose was used for doping before fabrication of patterned aluminum contacts. The implanted films were electrically characterized by the transfer length method (TLM) measuring a sheet resistance value as low as 171 M{omega}/square. The Schottky behavior was improved to ohmic behavior after several hours in thermal annealing treatments at 350 C, which allows to obtain a reasonable contact resistance values in the range from 8.6 to 26.8 k{omega}. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  14. Using data on social contacts to estimate age-specific transmission parameters for respiratory-spread infectious agents.

    NARCIS (Netherlands)

    Wallinga, Jacco; Teunis, Peter F M; Kretzschmar, Mirjam

    2006-01-01

    The estimation of transmission parameters has been problematic for diseases that rely predominantly on transmission of pathogens from person to person through small infectious droplets. Age-specific transmission parameters determine how such respiratory agents will spread among different age groups

  15. Race-Specific Adult-Plant Resistance in Winter Wheat to Stripe Rust and Characterization of Pathogen Virulence Patterns.

    Science.gov (United States)

    Milus, Eugene A; Moon, David E; Lee, Kevin D; Mason, R Esten

    2015-08-01

    Stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important disease of wheat in the Great Plains and southeastern United States. Growing resistant cultivars is the preferred means for managing stripe rust, but new virulence in the pathogen population overcomes some of the resistance. The objectives of this study were to characterize the stripe rust resistance in contemporary soft and hard red winter wheat cultivars, to characterize the virulence of P. striiformis f. sp. tritici isolates based on the resistances found in the cultivars, and to determine wheat breeders' perceptions on the importance and methods for achieving stripe rust resistance. Seedlings of cultivars were susceptible to recent isolates, indicating they lacked effective all-stage resistance. However, adult-plants were resistant or susceptible depending on the isolate, indicating they had race-specific adult-plant resistance. Using isolates collected from 1990 to 2013, six major virulence patterns were identified on adult plants of twelve cultivars that were selected as adult-plant differentials. Race-specific adult-plant resistance appears to be the only effective type of resistance protecting wheat from stripe rust in eastern United States. Among wheat breeders, the importance of incorporating stripe rust resistance into cultivars ranged from high to low depending on the frequency of epidemics in their region, and most sources of stripe rust resistance were either unknown or already overcome by virulence in the pathogen population. Breeders with a high priority for stripe rust resistance made most of their selections based on adult-plant reactions in the field, whereas breeders with a low priority for resistance based selections on molecular markers for major all-stage resistance genes.

  16. The impact of drug resistance on the risk of tuberculosis infection and disease in child household contacts: a cross sectional study.

    Science.gov (United States)

    Golla, Vera; Snow, Kathryn; Mandalakas, Anna M; Schaaf, H Simon; Du Preez, Karen; Hesseling, Anneke C; Seddon, James A

    2017-08-29

    The relative fitness of organisms causing drug-susceptible (DS) and multidrug-resistant (MDR) tuberculosis (TB) is unclear. We compared the risk of TB infection and TB disease in young child household contacts of adults with confirmed DS-TB and MDR-TB. In this cross-sectional analysis we included data from two community-based contact cohort investigation studies conducted in parallel in Cape Town, South Africa. Children <5 years of age with household exposure to an infectious TB case were included between August 2008 to June 2011. Children completed investigation for TB infection (tuberculin skin test) and TB disease (symptom evaluation, chest radiograph, bacteriology) in both studies using standard approaches. The impact of MDR-TB exposure on each covariate of TB infection and TB disease was assessed using univariable and multivariable logistic regression. Of 538 children included, 312 had DS-TB and 226 had MDR-TB exposure. 107 children with DS-TB exposure had TB infection (34.3%) vs. 101 (44.7%) of children with MDR-TB exposure (adjusted Odds Ratio [aOR]: 2.05; 95% confidence interval [CI]: 1.34-3.12). A total of 15 (6.6%) MDR-TB vs. 27 (8.7%) DS-TB child contacts had TB disease at enrolment (aOR: 0.43; 95% CI: 0.19-0.97). Our results suggest a higher risk of TB infection in child contacts with household MDR-TB vs. DS-TB exposure, but a lower risk of TB disease. Although potentially affected by residual confounding or selection bias, our results are consistent with the hypothesis of impaired virulence in MDR-TB strains in this setting.

  17. Applying "Spark Plasma Sintering" Technology to Enhance the Resistance to Contact Fatigue of Sintered Steel Based on Astaloy CRL

    Science.gov (United States)

    Rodziňák, D.; Čerňan, J.; Puchý, V.

    2017-12-01

    The article deals with the effect of porosity on the contact fatigue of sintered material type Astaloy CrL with 0.3 and 0.4% C. Sets of samples were used with densities beginning from the value of 7000 kg.m-3 to the value of almost 7859 kg.m-3 which represents almost zero porosity (compact material). It has been found out that the increase of compacting pressure applied simultaneously with temperature results in the reduction of porosity from the value of 9.10% to 0.0005% and increase in hardness from 145 to 193 HV10, depending on the carbon content. Logically there is also an increase in the fatigue life by the contact fatigue tests for the value of 50×106 cycles from the value of 900 MPa to 1150 MPa for samples with 0.3% of C and from 900 MPa to 1300 MPa for samples with 0.4% C. These investigations were also carried out in the past, but to achieve the reduction of porosity, different technonologies were used at each level such as double pressing, hot pressing, saturation, hot forging, etc. In this case, the single technology of "spark plasma sintering" making use of compacting at high temperatures is capable to continuously reduce porosity to zero.

  18. Long-Term Impact of Universal Contact Precautions on Rates of Multidrug-Resistant Organisms in ICUs: A Comparative Effectiveness Study.

    Science.gov (United States)

    Furuya, E Yoko; Cohen, Bevin; Jia, Haomiao; Larson, Elaine L

    2018-03-22

    OBJECTIVE To evaluate the impact of universal contact precautions (UCP) on rates of multidrug-resistant organisms (MDROs) in intensive care units (ICUs) over 9 years DESIGN Retrospective, nonrandomized observational study SETTING An 800-bed adult academic medical center in New York City PARTICIPANTS All patients admitted to 6 ICUs, 3 of which instituted UCP in 2007 METHODS Using a comparative effectiveness approach, we studied the longitudinal impact of UCP on MDRO incidence density rates, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and carbapenem-resistant Klebsiella pneumoniae. Data were extracted from a clinical research database for 2006-2014. Monthly MDRO rates were compared between the baseline period and the UCP period, utilizing time series analyses based on generalized linear models. The same models were also used to compare MDRO rates in the 3 UCP units to 3 ICUs without UCPs. RESULTS Overall, MDRO rates decreased over time, but there was no significant decrease in the trend (slope) during the UCP period compared to the baseline period for any of the 3 intervention units. Furthermore, there was no significant difference between UCP units (6.6% decrease in MDRO rates per year) and non-UCP units (6.0% decrease per year; P=.840). CONCLUSION The results of this 9-year study suggest that decreases in MDROs, including multidrug-resistant gram-negative bacilli, were more likely due to hospital-wide improvements in infection prevention during this period and that UCP had no detectable additional impact. Infect Control Hosp Epidemiol 2018;1-7.

  19. Overall and specific migration from multilayer high barrier food contact materials - kinetic study of cyclic polyester oligomers migration.

    Science.gov (United States)

    Úbeda, Sara; Aznar, Margarita; Vera, Paula; Nerín, Cristina; Henríquez, Luis; Taborda, Laura; Restrepo, Claudia

    2017-10-01

    Most multilayer high barrier materials used in food packaging have a polyurethane adhesive layer in their structures. In order to assess the safety of these materials, it is important to determine the compounds intentionally added to the adhesives (IAS) as well as those non-intentionally added substances (NIAS). During the manufacture of polyurethane adhesives, some by-products can be formed, such as cyclic polyester oligomers coming from the reaction between dicarboxylic acids and glycols. Since these compounds are not listed in the Regulation 10/2011/EU, they should not be found in migration above 0.01 mg/kg of simulant. In this study two flexible multilayer packaging materials were used and migration was evaluated in simulant A (ethanol 10% v/v), simulant B (acetic acid 3% w/v) and simulant ethanol 95% v/v during 10 days at 60ºC. Identification and quantification of non-volatile compounds was carried out by UPLC-MS-QTOF. Most of migrants were oligomers such as cyclic polyesters and caprolactam oligomers. Overall migration and specific migration of adipic acid-diethylene glycol and phthalic acid-diethylene glycol were monitored over time and analysed by UPLC-MS-TQ. In most cases, ethanol 95% v/v was the simulant with the highest concentration values. Overall migration kinetics followed a similar pattern than specific migration kinetics.

  20. Ti/Al Ohmic Contacts to n-Type GaN Nanowires

    Directory of Open Access Journals (Sweden)

    Gangfeng Ye

    2011-01-01

    Full Text Available Titanium/aluminum ohmic contacts to tapered n-type GaN nanowires with triangular cross-sections were studied. To extract the specific contact resistance, the commonly used transmission line model was adapted to the particular nanowire geometry. The most Al-rich composition of the contact provided a low specific contact resistance (mid 10−8 Ωcm2 upon annealing at 600 °C for 15 s, but it exhibited poor thermal stability due to oxidation of excess elemental Al remaining after annealing, as revealed by transmission electron microscopy. On the other hand, less Al-rich contacts required higher annealing temperatures (850 or 900 °C to reach a minimum specific contact resistance but exhibited better thermal stability. A spread in the specific contact resistance from contact to contact was tentatively attributed to the different facets that were contacted on the GaN nanowires with a triangular cross-section.

  1. PVC cling film in contact with cheese: health aspects related to global migration and specific migration of DEHA

    DEFF Research Database (Denmark)

    Petersen, Jens Højslev; Naamansen, Ebbe Tubæk; Nielsen, Preben Aagård

    1995-01-01

    Following exposure to the food simulant olive oil for 10 days at 5, 20 or 40 degrees C a global migration ranging from 20 to 30 mg/dm(2) was detected from a common 'low migration' PVC film plasticized with a mixture of di-(ethylhexyl)adipate (DEHA) and a polymeric plasticizer. In a laboratory...... experiment samples of cheese of the types most commonly consumed in Denmark were wrapped in this 'low migration' PVC film using a procedure simulating the actual pattern of use in retail shops. After a storage time of 2 h at 5 degrees C the level of DEHA was 45 mg/kg of cheese, which after 10 days increased...... to 150 mg DEHA per kg of cheese, corresponding to an estimated specific migration of 12 mg DEHA/dm(2) of cheese surface. Based on statistics on dietary habits it is concluded that the retail packaging of small portions of cheese even in a 'low migration' PVC cling film may lead to consumer intakes...

  2. Formation of a low-resistance and high reflectivity reflector on p-type GaN with a AgAl ohmic contact

    International Nuclear Information System (INIS)

    Kim, Ja-Yeon; Park, Seong-Ju; Kwon, Min-Ki

    2012-01-01

    In this study, we investigate the effect of the Al composition of a AgAl alloy reflector deposited on a p-GaN layer for use in a high-efficiency GaN flip-chip light-emitting diode (FCLED) or n-type sideup vertical LEDs. When the Al composition was 3%, the AgAl reflector showed low resistance, high reflectance and thermally stable ohmic contact properties. For an Al composition of 3% in the AgAl reflector, the optical output power was improved by 50%, and the current-voltage characteristic was improved compared to that for a Ag reflector. These results clearly indicate that a AgAl layer on p-GaN constitutes a promising reflector and ohmic scheme for achieving high-brightness FCLEDs and vertical LEDs.

  3. Risk Factors for Nasal Colonization by Methicillin-Resistant Staphylococci in Healthy Humans in Professional Daily Contact with Companion Animals in Portugal.

    Science.gov (United States)

    Rodrigues, Ana Catarina; Belas, Adriana; Marques, Cátia; Cruz, Luís; Gama, Luís T; Pomba, Constança

    2017-09-18

    Methicillin-resistant staphylococci (MRS), namely Staphylococcus aureus (MRSA) and Staphylococcus pseudintermedius (MRSP), are opportunistic agents of great importance in human and veterinary medicine. The aims of this study were to investigate the frequency, persistence, and risk factors associated with nasal colonization by MRS in people in daily contact with animals in Portugal. Seventy-nine out of 129 (61.2%) participants were found to be colonized by, at least, one methicillin-resistant (MR) staphylococci species (MR Staphylococcus epidermidis [n = 68], MRSA [n = 19], MR Staphylococcus haemolyticus [n = 7], MRSP [n = 2], and other coagulase-negative staphylococci [n = 4]). Three lineages were identified among the MRSA isolates (n = 7): the major human healthcare clone in Portugal (ST22-t032-IV, n = 3), the livestock-associated MRSA (ST398-t108-V, n = 3), and the New York-/Japan-related clone (ST105-t002-II, n = 1). MRSP isolates belonged to the European clone ST71-II-III. We identified two risk factors for nasal colonization by MRS in healthy humans: (i) being a veterinary professional (veterinarian and veterinary nurse) (p < 0.0001, odds ratio [OR] = 6.369, 95% confidence interval [CI, 2.683-15.122]) and (ii) have contacted with one MRSA- or MRSP-positive animal (p = 0.0361, OR = 2.742, 95% CI [1.067-7.045]). The follow-up study revealed that the majority (85%) remain colonized. This study shows that MRS in veterinary clinical practice is a professional hazard and highlights the need to implement preventive measures to minimize spread.

  4. Non-specific activities of the major herbicide-resistance gene BAR.

    Science.gov (United States)

    Christ, Bastien; Hochstrasser, Ramon; Guyer, Luzia; Francisco, Rita; Aubry, Sylvain; Hörtensteiner, Stefan; Weng, Jing-Ke

    2017-12-01

    Bialaphos resistance (BAR) and phosphinothricin acetyltransferase (PAT) genes, which convey resistance to the broad-spectrum herbicide phosphinothricin (also known as glufosinate) via N-acetylation, have been globally used in basic plant research and genetically engineered crops 1-4 . Although early in vitro enzyme assays showed that recombinant BAR and PAT exhibit substrate preference toward phosphinothricin over the 20 proteinogenic amino acids 1 , indirect effects of BAR-containing transgenes in planta, including modified amino acid levels, have been seen but without the identification of their direct causes 5,6 . Combining metabolomics, plant genetics and biochemical approaches, we show that transgenic BAR indeed converts two plant endogenous amino acids, aminoadipate and tryptophan, to their respective N-acetylated products in several plant species. We report the crystal structures of BAR, and further delineate structural basis for its substrate selectivity and catalytic mechanism. Through structure-guided protein engineering, we generated several BAR variants that display significantly reduced non-specific activities compared with its wild-type counterpart in vivo. The transgenic expression of enzymes can result in unintended off-target metabolism arising from enzyme promiscuity. Understanding such phenomena at the mechanistic level can facilitate the design of maximally insulated systems featuring heterologously expressed enzymes.

  5. Sequence-Specific Targeting of Bacterial Resistance Genes Increases Antibiotic Efficacy.

    Science.gov (United States)

    Ayhan, Dilay Hazal; Tamer, Yusuf Talha; Akbar, Mohammed; Bailey, Stacey M; Wong, Michael; Daly, Seth M; Greenberg, David E; Toprak, Erdal

    2016-09-01

    The lack of effective and well-tolerated therapies against antibiotic-resistant bacteria is a global public health problem leading to prolonged treatment and increased mortality. To improve the efficacy of existing antibiotic compounds, we introduce a new method for strategically inducing antibiotic hypersensitivity in pathogenic bacteria. Following the systematic verification that the AcrAB-TolC efflux system is one of the major determinants of the intrinsic antibiotic resistance levels in Escherichia coli, we have developed a short antisense oligomer designed to inhibit the expression of acrA and increase antibiotic susceptibility in E. coli. By employing this strategy, we can inhibit E. coli growth using 2- to 40-fold lower antibiotic doses, depending on the antibiotic compound utilized. The sensitizing effect of the antisense oligomer is highly specific to the targeted gene's sequence, which is conserved in several bacterial genera, and the oligomer does not have any detectable toxicity against human cells. Finally, we demonstrate that antisense oligomers improve the efficacy of antibiotic combinations, allowing the combined use of even antagonistic antibiotic pairs that are typically not favored due to their reduced activities.

  6. Design of a soil cutting resistance sensor for application in site-specific tillage.

    Science.gov (United States)

    Agüera, Juan; Carballido, Jacob; Gil, Jesús; Gliever, Chris J; Perez-Ruiz, Manuel

    2013-05-10

    One objective of precision agriculture is to provide accurate information about soil and crop properties to optimize the management of agricultural inputs to meet site-specific needs. This paper describes the development of a sensor equipped with RTK-GPS technology that continuously and efficiently measures soil cutting resistance at various depths while traversing the field. Laboratory and preliminary field tests verified the accuracy of this prototype soil strength sensor. The data obtained using a hand-operated soil cone penetrometer was used to evaluate this field soil compaction depth profile sensor. To date, this sensor has only been tested in one field under one gravimetric water content condition. This field test revealed that the relationships between the soil strength profile sensor (SSPS) cutting force and soil cone index values are assumed to be quadratic for the various depths considered: 0-10, 10-20 and 20-30 cm (r2 = 0.58, 0.45 and 0.54, respectively). Soil resistance contour maps illustrated its practical value. The developed sensor provides accurate, timely and affordable information on soil properties to optimize resources and improve agricultural economy.

  7. A novel multiple super junction power device structure with low specific on-resistance

    International Nuclear Information System (INIS)

    Zhu Hui; Li Haiou; Li Qi; Huang Yuanhao; Xu Xiaoning; Zhao Hailiang

    2014-01-01

    A novel multiple super junction (MSJ) LDMOS power device is proposed to decrease R on due to lateral and vertical interactions between the N-pillar and P-pillar. In the studied device: multiple layers of SJ are introduced oppositely under surface SJ; when compared with 2D-depleting of the conventional super junction (CSJ), a 3D-depleted effect is formed in the MSJ thanks to vertical electric field modulation; and, current distribution is improved by deep drain, which increases the drift doping concentration and results in a lower on-resistance. The high electric field around the drain region by substrate-assisted depleted effect is reduced due to the charge balance result from the electric field shielding effect of the bottom SJ, which causes the uniform electric field in the drift region and the high breakdown voltage. The numerical simulation results indicate that the specific on-resistance of the MSJ device is reduced by 42% compared with that of CSJ device, while maintaining a high breakdown voltage; the cell pitch of the device is 12 μm. (semiconductor devices)

  8. Sequence-Specific Targeting of Bacterial Resistance Genes Increases Antibiotic Efficacy

    Science.gov (United States)

    Wong, Michael; Daly, Seth M.; Greenberg, David E.; Toprak, Erdal

    2016-01-01

    The lack of effective and well-tolerated therapies against antibiotic-resistant bacteria is a global public health problem leading to prolonged treatment and increased mortality. To improve the efficacy of existing antibiotic compounds, we introduce a new method for strategically inducing antibiotic hypersensitivity in pathogenic bacteria. Following the systematic verification that the AcrAB-TolC efflux system is one of the major determinants of the intrinsic antibiotic resistance levels in Escherichia coli, we have developed a short antisense oligomer designed to inhibit the expression of acrA and increase antibiotic susceptibility in E. coli. By employing this strategy, we can inhibit E. coli growth using 2- to 40-fold lower antibiotic doses, depending on the antibiotic compound utilized. The sensitizing effect of the antisense oligomer is highly specific to the targeted gene’s sequence, which is conserved in several bacterial genera, and the oligomer does not have any detectable toxicity against human cells. Finally, we demonstrate that antisense oligomers improve the efficacy of antibiotic combinations, allowing the combined use of even antagonistic antibiotic pairs that are typically not favored due to their reduced activities. PMID:27631336

  9. Specific heat, Electrical resistivity and Electronic band structure properties of noncentrosymmetric Th7Fe3superconductor.

    Science.gov (United States)

    Tran, V H; Sahakyan, M

    2017-11-17

    Noncentrosymmetric superconductor Th 7 Fe 3 has been investigated by means of specific heat, electrical resisitivity measurements and electronic properties calculations. Sudden drop in the resistivity at 2.05 ± 0.15 K and specific heat jump at 1.98 ± 0.02 K are observed, rendering the superconducting transition. A model of two BCS-type gaps appears to describe the zero-magnetic-field specific heat better than those based on the isotropic BCS theory or anisotropic functions. A positive curvature of the upper critical field H c2 (T c ) and nonlinear field dependence of the Sommerfeld coefficient at 0.4 K qualitatively support the two-gap scenario, which predicts H c2 (0) = 13 kOe. The theoretical densities of states and electronic band structures (EBS) around the Fermi energy show a mixture of Th 6d- and Fe 3d-electrons bands, being responsible for the superconductivity. Furthermore, the EBS and Fermi surfaces disclose significantly anisotropic splitting associated with asymmetric spin-orbit coupling (ASOC). The ASOC sets up also multiband structure, which presumably favours a multigap superconductivity. Electron Localization Function reveals the existence of both metallic and covalent bonds, the latter may have different strengths depending on the regions close to the Fe or Th atoms. The superconducting, electronic properties and implications of asymmetric spin-orbit coupling associated with noncentrosymmetric structure are discussed.

  10. Effects of resistance training on classic and specific bioelectrical impedance vector analysis in elderly women.

    Science.gov (United States)

    Fukuda, David H; Stout, Jeffrey R; Moon, Jordan R; Smith-Ryan, Abbie E; Kendall, Kristina L; Hoffman, Jay R

    2016-02-01

    Raw bioelectrical impedance analysis (BIA) data [resistance (R); reactance (Xc)] through bioelectrical impedance vector analysis (BIVA) and phase angle (PhA) have been used to evaluate cellular function and hydration status. The purpose of this investigation was to examine the effects of resistance training (RT) on classic and specific BIVA in elderly women. Twenty women (mean ± SD; age: 71.9 ± 6.9 years; BMI: 24.5 ± 3.0 kg m(-2)) completed a 6-month RT program. Whole-body, single-frequency BIA, body geometry, and leg strength (5RM) measures were completed at baseline (t0), 3 months (t3), and 6 months (t6). The mean impedance vector displacements were compared using Hotelling's T(2) test to evaluate changes in R and Xc relative to height (R/ht; Xc/ht) or body volume (Rsp; Xcsp) estimated from the arms, legs, and trunk. 5RM, PhA, and BIVA variables were compared using ANOVA. PhA improved at t6 (p < 0.01), while 5RM improved at t3 and t6 (p < 0.01). Using classic BIVA, 6 months (T(2) = 31.6; p < 0.01), but not 3 months of RT (T(2) = 4.5; p = 0.20), resulted in significant vector migration. Using specific BIVA, 6 months (T(2) = 24.4; p < 0.01), but not 3 months of RT (T(2) = 5.5; p = 0.10), also resulted in significant vector migration. 5RM was correlated to both PhA (r = 0.48-56) and Xcsp (r = 0.45-53) at all time points. Vector displacements were likely the result of improved cellular integrity (Xcsp) and cellular health (PhA). Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Pathotype-specific QTL for stem rust resistance in Lolium perenne.

    Science.gov (United States)

    Pfender, W F; Slabaugh, M E

    2013-05-01

    A genetic map populated with RAD and SSR markers was created from F1 progeny of a stem rust-susceptible and stem rust-resistant parent of perennial ryegrass (Lolium perenne). The map supplements a previous map of this population by having markers in common with several other Lolium spp. maps including EST-SSR anchor markers from a consensus map published by other researchers. A QTL analysis was conducted with disease severity and infection type data obtained by controlled inoculation of the population with each of two previously characterized pathotypes of Puccinia graminis subsp. graminicola that differ in virulence to different host plant genotypes in the F1 population. Each pathotype activated a specific QTL on one linkage group (LG): qLpPg1 on LG7 for pathotype 101, or qLpPg2 on LG1 for pathotype 106. Both pathotypes also activated a third QTL in common, qLpPg3 on LG6. Anchor markers, present on a consensus map, were located in proximity to each of the three QTL. These QTL had been detected also in previous experiments in which a genetically heterogeneous inoculum of the stem rust pathogen activated all three QTL together. The results of this and a previous study are consistent with the involvement of the pathotype-specific QTL in pathogen recognition and the pathotype-nonspecific QTL in a generalized resistance response. By aligning the markers common to other published reports, it appears that two and possibly all three of the stem rust QTL reported here are in the same general genomic regions containing some of the L. perenne QTL reported to be activated in response to the crown rust pathogen (P. coronata).

  12. Mapping of a Novel Race Specific Resistance Gene to Phytophthora Root Rot of Pepper (Capsicum annuum) Using Bulked Segregant Analysis Combined with Specific Length Amplified Fragment Sequencing Strategy.

    Science.gov (United States)

    Xu, Xiaomei; Chao, Juan; Cheng, Xueli; Wang, Rui; Sun, Baojuan; Wang, Hengming; Luo, Shaobo; Xu, Xiaowan; Wu, Tingquan; Li, Ying

    2016-01-01

    Phytophthora root rot caused by Phytophthora capsici (P. capsici) is a serious limitation to pepper production in Southern China, with high temperature and humidity. Mapping PRR resistance genes can provide linked DNA markers for breeding PRR resistant varieties by molecular marker-assisted selection (MAS). Two BC1 populations and an F2 population derived from a cross between P. capsici-resistant accession, Criollo de Morelos 334 (CM334) and P. capsici-susceptible accession, New Mexico Capsicum Accession 10399 (NMCA10399) were used to investigate the genetic characteristics of PRR resistance. PRR resistance to isolate Byl4 (race 3) was controlled by a single dominant gene, PhR10, that was mapped to an interval of 16.39Mb at the end of the long arm of chromosome 10. Integration of bulked segregant analysis (BSA) and Specific Length Amplified Fragment sequencing (SLAF-seq) provided an efficient genetic mapping strategy. Ten polymorphic Simple Sequence Repeat (SSR) markers were found within this region and used to screen the genotypes of 636 BC1 plants, delimiting PhR10 to a 2.57 Mb interval between markers P52-11-21 (1.5 cM away) and P52-11-41 (1.1 cM). A total of 163 genes were annotated within this region and 31 were predicted to be associated with disease resistance. PhR10 is a novel race specific gene for PRR, and this paper describes linked SSR markers suitable for marker-assisted selection of PRR resistant varieties, also laying a foundation for cloning the resistance gene.

  13. Mapping of a Novel Race Specific Resistance Gene to Phytophthora Root Rot of Pepper (Capsicum annuum Using Bulked Segregant Analysis Combined with Specific Length Amplified Fragment Sequencing Strategy.

    Directory of Open Access Journals (Sweden)

    Xiaomei Xu

    Full Text Available Phytophthora root rot caused by Phytophthora capsici (P. capsici is a serious limitation to pepper production in Southern China, with high temperature and humidity. Mapping PRR resistance genes can provide linked DNA markers for breeding PRR resistant varieties by molecular marker-assisted selection (MAS. Two BC1 populations and an F2 population derived from a cross between P. capsici-resistant accession, Criollo de Morelos 334 (CM334 and P. capsici-susceptible accession, New Mexico Capsicum Accession 10399 (NMCA10399 were used to investigate the genetic characteristics of PRR resistance. PRR resistance to isolate Byl4 (race 3 was controlled by a single dominant gene, PhR10, that was mapped to an interval of 16.39Mb at the end of the long arm of chromosome 10. Integration of bulked segregant analysis (BSA and Specific Length Amplified Fragment sequencing (SLAF-seq provided an efficient genetic mapping strategy. Ten polymorphic Simple Sequence Repeat (SSR markers were found within this region and used to screen the genotypes of 636 BC1 plants, delimiting PhR10 to a 2.57 Mb interval between markers P52-11-21 (1.5 cM away and P52-11-41 (1.1 cM. A total of 163 genes were annotated within this region and 31 were predicted to be associated with disease resistance. PhR10 is a novel race specific gene for PRR, and this paper describes linked SSR markers suitable for marker-assisted selection of PRR resistant varieties, also laying a foundation for cloning the resistance gene.

  14. Contact allergy to the 26 specific fragrance ingredients to be declared on cosmetic products in accordance with the EU cosmetics directive.

    Science.gov (United States)

    Heisterberg, Maria V; Menné, Torkil; Johansen, Jeanne D

    2011-11-01

    Fragrance ingredients are a frequent cause of allergic contact dermatitis. The EU Cosmetics Directive states that 26 specific fragrance ingredients, known to cause allergic contact dermatitis, must be declared on the ingredient lists of cosmetic products. To investigate frequencies of sensitization to the 26 individual fragrances and evaluate their importance as screening markers of fragrance allergy. This was a retrospective study based on data from the Department of Dermato-Allergology, Copenhagen University Hospital Gentofte. Eczema patients (n = 1508) were patch tested (January 2008 to July 2010) with the 26 fragrance ingredients. Sensitization to the 26 fragrances was identified in 115 (7.6%) subjects. The most frequent allergens were Evernia furfuracea (n = 50), Evernia prunastri (n = 31), and hydroxyisohexyl 3-cyclohexene carboxaldehyde (n = 24). Including fragrance mix I, fragrance mix II and Myroxylon pereirae, 196 (13.0%) had a fragrance allergy. Testing with the 26 fragrances additionally identified 23 subjects who would otherwise have gone undetected. The majority (75.7%) of positive reactions to the 26 fragrances were of clinical relevance. Sensitization to the 26 individual fragrance ingredients was identified in 7.6% of the subjects patch tested. Most reactions were of clinical relevance. Fragrance-allergic subjects would be missed if testing with the individual fragrance ingredients was not performed. © 2011 John Wiley & Sons A/S.

  15. A Continuous 3D-Graphene Network to Overcome Threshold Issues and Contact Resistance in Thermally Conductive Graphene Nanocomposites

    Directory of Open Access Journals (Sweden)

    Federico Conrado

    2017-01-01

    Full Text Available In order to overcome thermal resistance issues in polymeric matrix composites, self-standing graphene aerogels were synthetized and infiltrated with an epoxy resin, in order to create conductive preferential pathways through which heat can be easily transported. These continuous highly thermally conductive 3D-structures show, due to the high interconnection degree of graphene flakes, enhanced transport properties. Two kinds of aerogels were investigated, obtained by hydrothermal synthesis (HS and ice-templated direct freeze synthesis (DFS. Following HS method an isotropic structure is obtained, and following DFS method instead an anisotropic arrangement of graphene flakes results. The density of the structure can be tuned leading to a different amount of graphene inside the final composite. The residual oxygen, known to be detrimental to thermal properties, was removed by thermal treatment before the infiltration process. With 1,25 wt.% of graphene, using HS method, the thermal conductivity of the polymeric resin was increased by 80%, suggesting that this technique is a valid route to improve the thermal performance of graphene-based composites. When preferential orientation of the filler was present (DFS case, thermal conductivity was increased more than 25% with a graphene content of only 0,27 wt.%, demonstrating that oriented structures can further improve the thermal transport efficiency.

  16. Genetic variation and host-parasite specificity of Striga resistance and tolerance in rice: the need for predictive breeding.

    Science.gov (United States)

    Rodenburg, Jonne; Cissoko, Mamadou; Kayongo, Nicholas; Dieng, Ibnou; Bisikwa, Jenipher; Irakiza, Runyambo; Masoka, Isaac; Midega, Charles A O; Scholes, Julie D

    2017-05-01

    The parasitic weeds Striga asiatica and Striga hermonthica cause devastating yield losses to upland rice in Africa. Little is known about genetic variation in host resistance and tolerance across rice genotypes, in relation to virulence differences across Striga species and ecotypes. Diverse rice genotypes were phenotyped for the above traits in S. asiatica- (Tanzania) and S. hermonthica-infested fields (Kenya and Uganda) and under controlled conditions. New rice genotypes with either ecotype-specific or broad-spectrum resistance were identified. Resistance identified in the field was confirmed under controlled conditions, providing evidence that resistance was largely genetically determined. Striga-resistant genotypes contributed to yield security under Striga-infested conditions, although grain yield was also determined by the genotype-specific yield potential and tolerance. Tolerance, the physiological mechanism mitigating Striga effects on host growth and physiology, was unrelated to resistance, implying that any combination of high, medium or low levels of these traits can be found across rice genotypes. Striga virulence varies across species and ecotypes. The extent of Striga-induced host damage results from the interaction between parasite virulence and genetically determined levels of host-plant resistance and tolerance. These novel findings support the need for predictive breeding strategies based on knowledge of host resistance and parasite virulence. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  17. A multiple genome analysis of Mycobacterium tuberculosis reveals specific novel genes and mutations associated with pyrazinamide resistance.

    Science.gov (United States)

    Sheen, Patricia; Requena, David; Gushiken, Eduardo; Gilman, Robert H; Antiparra, Ricardo; Lucero, Bryan; Lizárraga, Pilar; Cieza, Basilio; Roncal, Elisa; Grandjean, Louis; Pain, Arnab; McNerney, Ruth; Clark, Taane G; Moore, David; Zimic, Mirko

    2017-10-11

    Tuberculosis (TB) is a major global health problem and drug resistance compromises the efforts to control this disease. Pyrazinamide (PZA) is an important drug used in both first and second line treatment regimes. However, its complete mechanism of action and resistance remains unclear. We genotyped and sequenced the complete genomes of 68 M. tuberculosis strains isolated from unrelated TB patients in Peru. No clustering pattern of the strains was verified based on spoligotyping. We analyzed the association between PZA resistance with non-synonymous mutations and specific genes. We found mutations in pncA and novel genes significantly associated with PZA resistance in strains without pncA mutations. These included genes related to transportation of metal ions, pH regulation and immune system evasion. These results suggest potential alternate mechanisms of PZA resistance that have not been found in other populations, supporting that the antibacterial activity of PZA may hit multiple targets.

  18. A multiple genome analysis of Mycobacterium tuberculosis reveals specific novel genes and mutations associated with pyrazinamide resistance

    KAUST Repository

    Sheen, Patricia

    2017-10-11

    Tuberculosis (TB) is a major global health problem and drug resistance compromises the efforts to control this disease. Pyrazinamide (PZA) is an important drug used in both first and second line treatment regimes. However, its complete mechanism of action and resistance remains unclear.We genotyped and sequenced the complete genomes of 68 M. tuberculosis strains isolated from unrelated TB patients in Peru. No clustering pattern of the strains was verified based on spoligotyping. We analyzed the association between PZA resistance with non-synonymous mutations and specific genes. We found mutations in pncA and novel genes significantly associated with PZA resistance in strains without pncA mutations. These included genes related to transportation of metal ions, pH regulation and immune system evasion.These results suggest potential alternate mechanisms of PZA resistance that have not been found in other populations, supporting that the antibacterial activity of PZA may hit multiple targets.

  19. Specification for corrosion-resisting chromium and chromium-nickel steel welding rods and bare electrodes - approved 1969

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    This specification covers corrosion-resisting chromium and chromium-nickel steel welding rods for use with the atomic hydrogen and gas-tungsten-arc welding processes and bare electrodes for use with the submerged arc and gas metal-arc welding processes. These welding rods and electrodes include those alloy steels designated as corrosion- or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4% and nickel does not exceed 50%

  20. Development of physiological resistance and its stage specificity in Culex quinquefasciatus after selection with deltamethrin in Assam, India

    Directory of Open Access Journals (Sweden)

    Manas Sarkar

    2009-08-01

    Full Text Available The study investigated the development and stage specificity of physiological resistance to insecticides in a colony of Culex quinquefasciatus Say (Diptera: Culicidae mosquitoes, which are vectors of bancroftian filariasis in India, after selection with deltamethrin. Resistance was selected by exposing the larvae to the concentration of deltamethrin that caused 50% mortality in the tested population (i.e., LC50. Under continuous selection pressure, the LC50 increased steadily in subsequent generations. The estimated LC50 for the F0 generation was 0.409 μg/L; the LC50 first displayed a substantial increase in the F5 generation (5.616 μg/L and reached 121.902 μg/L in the F10 generation. The objective of this study was to establish a deltamethrin-resistant colony to develop a research programme that will study the evolution of physiological resistance patterns and stage-specific resistance responses in Cx. quinquefasciatus larvae and adults under laboratory conditions. An approximately 298-fold increase in resistance was recorded after 10 generations, as evidenced by the resistance ratio (RR50. The progress and effect of the selection pressure in the adult stage was monitored with the World Health Organisation (WHO diagnostic test. The mortality, as observed using the WHO diagnostic test, declined significantly from the F5 generation (85% onwards and the highest rate of survival (65% was observed in the F10 generation.

  1. Specific balance training included in an endurance-resistance exercise program improves postural balance in elderly patients undergoing haemodialysis.

    Science.gov (United States)

    Frih, Bechir; Mkacher, Wajdi; Jaafar, Hamdi; Frih, Ameur; Ben Salah, Zohra; El May, Mezry; Hammami, Mohamed

    2018-04-01

    The purpose of this study was to evaluate the effects of 6 months of specific balance training included in endurance-resistance program on postural balance in haemodialysis (HD) patients. Forty-nine male patients undergoing HD were randomly assigned to an intervention group (balance training included in an endurance-resistance training, n = 26) or a control group (resistance-endurance training only, n = 23). Postural control was assessed using six clinical tests; Timed Up and Go test, Tinetti Mobility Test, Berg Balance Scale, Unipodal Stance test, Mini-Balance Evaluation Systems Test and Activities Balance Confidence scale. All balance measures increased significantly after the period of rehabilitation training in the intervention group. Only the Timed Up and Go, Berg Balance Scale, Mini-Balance Evaluation Systems Test and Activities Balance Confidence scores were improved in the control group. The ranges of change in these tests were greater in the balance training group. In HD patients, specific balance training included in a usual endurance-resistance training program improves static and dynamic balance better than endurance-resistance training only. Implications for rehabilitation Rehabilitation using exercise in haemodialysis patients improved global mobility and functional abilities. Specific balance training included in usual endurance resistance training program could lead to improved static and dynamic balance.

  2. Exposure to dairy manure leads to greater antibiotic resistance and increased mass-specific respiration in soil microbial communities.

    Science.gov (United States)

    Wepking, Carl; Avera, Bethany; Badgley, Brian; Barrett, John E; Franklin, Josh; Knowlton, Katharine F; Ray, Partha P; Smitherman, Crystal; Strickland, Michael S

    2017-03-29

    Intensifying livestock production to meet the demands of a growing global population coincides with increases in both the administration of veterinary antibiotics and manure inputs to soils. These trends have the potential to increase antibiotic resistance in soil microbial communities. The effect of maintaining increased antibiotic resistance on soil microbial communities and the ecosystem processes they regulate is unknown. We compare soil microbial communities from paired reference and dairy manure-exposed sites across the USA. Given that manure exposure has been shown to elicit increased antibiotic resistance in soil microbial communities, we expect that manure-exposed sites will exhibit (i) compositionally different soil microbial communities, with shifts toward taxa known to exhibit resistance; (ii) greater abundance of antibiotic resistance genes; and (iii) corresponding maintenance of antibiotic resistance would lead to decreased microbial efficiency. We found that bacterial and fungal communities differed between reference and manure-exposed sites. Additionally, the β-lactam resistance gene ampC was 5.2-fold greater under manure exposure, potentially due to the use of cephalosporin antibiotics in dairy herds. Finally, ampC abundance was positively correlated with indicators of microbial stress, and microbial mass-specific respiration, which increased 2.1-fold under manure exposure. These findings demonstrate that the maintenance of antibiotic resistance associated with manure inputs alters soil microbial communities and ecosystem function. © 2017 The Author(s).

  3. Methicillin-resistant and methicillin-susceptible Staphylococcus aureus in dairy sheep and in-contact humans: An intra-farm study.

    Science.gov (United States)

    Carfora, V; Giacinti, G; Sagrafoli, D; Marri, N; Giangolini, G; Alba, P; Feltrin, F; Sorbara, L; Amoruso, R; Caprioli, A; Amatiste, S; Battisti, A

    2016-06-01

    Staphylococcus aureus is involved in a wide variety of diseases in humans and animals, and it is considered one of the most significant etiological agents of intramammary infection in dairy ruminants, causing both clinical and subclinical infections. In this study, the intra-farm prevalence and circulation of methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) were investigated on an Italian dairy sheep farm previously identified as MRSA-positive by testing bulk tank milk (first isolation in 2012). Human samples (nasal swabs, hand skin samples, and oropharyngeal swabs) from 3 persons working in close contact with the animals were also collected, and the genetic characteristics and relatedness of the MRSA isolates from human and animal sources within the farm were investigated. After 2yr from the first isolation, we confirmed the presence of the same multidrug-resistant strain of MRSA sequence type (ST)1, clonal complex (CC)1, spa type t127, staphylococcal cassette chromosome mec (SCCmec) type IVa, showing identical pulsed field gel electrophoresis (PFGE) and resistance profiles at the farm level in bulk tank milk. Methicillin-resistant S. aureus isolates were detected in 2 out of 556 (0.34%) individual milk samples, whereas MSSA isolates were detected in 10 samples (1.8%). The MRSA were further isolated from udder skin samples from the 2 animals that were MRSA-positive in milk and in 2 of the 3 examined farm personnel. All MRSA isolates from both ovine and human samples belonged to ST(CC)1, spa type t127, SCCmec type IVa, with some isolates from animals harboring genes considered markers of human adaptation. In contrast, all MSSA isolates belonged to ruminant-associated CC130, ST700, spa type t528. Analysis by PFGE performed on selected MRSA isolates of human and animal origin identified 2 closely related (96.3% similarity) pulsotypes, displaying only minimal differences in gene profiles (e.g., presence of the immune evasion cluster

  4. Effect of Operating Parameters and Chemical Additives on Crystal Habit and Specific Cake Resistance of Zinc Hydroxide Precipitates

    Energy Technology Data Exchange (ETDEWEB)

    Alwin, Jennifer Louise [New Mexico State Univ., Las Cruces, NM (United States)

    1999-08-01

    The effect of process parameters and chemical additives on the specific cake resistance of zinc hydroxide precipitates was investigated. The ability of a slurry to be filtered is dependent upon the particle habit of the solid and the particle habit is influenced by certain process variables. The process variables studied include neutralization temperature, agitation type, and alkalinity source used for neutralization. Several commercially available chemical additives advertised to aid in solid/liquid separation were also examined in conjunction with hydroxide precipitation. A statistical analysis revealed that the neutralization temperature and the source of alkalinity were statistically significant in influencing the specific cake resistance of zinc hydroxide precipitates in this study. The type of agitation did not significantly effect the specific cake resistance of zinc hydroxide precipitates. The use of chemical additives in conjunction with hydroxide precipitation had a favorable effect on the filterability. The morphology of the hydroxide precipitates was analyzed using scanning electron microscopy.

  5. Incremental stiffness and electrical contact conductance in the contact of rough finite bodies

    Science.gov (United States)

    Barber, J. R.

    2013-01-01

    If two half spaces are in contact, there exists a formal mathematical relation between the electrical contact resistance and the incremental elastic compliance. Here, this relation is extended to the contact of finite bodies. In particular, it is shown that the additional resistance due to roughness of the contacting surfaces (the interface resistance) bears a similar relation to the additional compliance as that obtained for the total resistance in the half-space problem.

  6. A low specific on-resistance SOI MOSFET with dual gates and a recessed drain

    International Nuclear Information System (INIS)

    Luo Xiao-Rong; Hu Gang-Yi; Zhang Zheng-Yuan; Luo Yin-Chun; Fan Ye; Wang Xiao-Wei; Fan Yuan-Hang; Cai Jin-Yong; Wang Pei; Zhou Kun

    2013-01-01

    A low specific on-resistance (R on,sp ) integrable silicon-on-insulator (SOI) metal-oxide semiconductor field-effect transistor (MOSFET) is proposed and investigated by simulation. The MOSFET features a recessed drain as well as dual gates, which consist of a planar gate and a trench gate extended to the buried oxide layer (BOX) (DGRD MOSFET). First, the dual gates form dual conduction channels, and the extended trench gate also acts as a field plate to improve the electric field distribution. Second, the combination of the trench gate and the recessed drain widens the vertical conduction area and shortens the current path. Third, the P-type top layer not only enhances the drift doping concentration but also modulates the surface electric field distributions. All of these sharply reduce R on,sp and maintain a high breakdown voltage (BV). The BV of 233 V and R on,sp of 4.151 mΩ·cm 2 (V GS = 15 V) are obtained for the DGRD MOSFET with 15-μm half-cell pitch. Compared with the trench gate SOI MOSFET and the conventional MOSFET, R on,sp of the DGRD MOSFET decreases by 36% and 33% with the same BV, respectively. The trench gate extended to the BOX synchronously acts as a dielectric isolation trench, simplifying the fabrication processes. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Contact allergy to nickel: patch test score correlates with IL-5, but not with IFN-gamma nickel-specific secretion by peripheral blood lymphocytes.

    Science.gov (United States)

    Czarnobilska, Ewa; Jenner, Bartosz; Kaszuba-Zwoinska, Jolanta; Kapusta, Maria; Obtułowicz, Krystyna; Thor, Piotr; Spiewak, Radosław

    2009-01-01

    Traditionally, allergic contact dermatitis (ACD) has been associated with the activity of Th1 lymphocytes that secrete interferon gamma. Recent evidence indicates that other cells, e.g. interleukin 5 (IL-5)-secreting Th2 or Tc2 cells may be among the key effectors of ACD. The aim of the present study was to assess the influence of nickel-specific IFN-gamma secretion (marker of Th1 and Tc1 activity) and IL-5 secretion (Th2 and Tc2) on the clinical outcome (patch test score) in nickel-allergic patients. 40 women with suspicion of ACD were involved, aged from 14-54 (median 31.5) years. They were patch tested with NiSO(4). Peripheral blood mononuclear cells (PBMC) from the patients were cultured and analysed for IFN-gamma and IL-5 secretion in response to NiSO(4). A series of statistical models (classical logit or cloglog link function) were used. We demonstrate that nickel-specific IL-5 secretion by PBMC is correlated with the intensity of patch test reaction (p=0.05), with no significant effect of IFN-gamma. An increase in the nickel-specific IL-5 secretion from PBMC by 10 pg/ml is associated with a 10-20% increase (depending on statistical model) in the odds ratio of the patient to have a higher patch test score. These findings support the assumption that cells secreting IL-5 (e.g. Th2, Tc2) play a more important role in the pathogenesis of ACD than previously thought.

  8. Laser-treated stainless steel mini-screw implants: 3D surface roughness, bone-implant contact, and fracture resistance analysis.

    Science.gov (United States)

    Kang, He-Kyong; Chu, Tien-Min; Dechow, Paul; Stewart, Kelton; Kyung, Hee-Moon; Liu, Sean Shih-Yao

    2016-04-01

    This study investigated the biomechanical properties and bone-implant intersurface response of machined and laser surface-treated stainless steel (SS) mini-screw implants (MSIs). Forty-eight 1.3mm in diameter and 6mm long SS MSIs were divided into two groups. The control (machined surface) group received no surface treatment; the laser-treated group received Nd-YAG laser surface treatment. Half in each group was used for examining surface roughness (Sa and Sq), surface texture, and facture resistance. The remaining MSIs were placed in the maxilla of six skeletally mature male beagle dogs in a randomized split-mouth design. A pair with the same surface treatment was placed on the same side and immediately loaded with 200 g nickel-titanium coil springs for 8 weeks. After killing, the bone-implant contact (BIC) for each MSI was calculated using micro computed tomography. Analysis of variance model and two-sample t test were used for statistical analysis with a significance level of P titanium alloy MSIs. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  9. The Effect of CuSn Intermetallics on the Interstrand Contact Resistance in Superconducting Cables for the Large Hadron Collider (LHC)

    CERN Document Server

    Scheuerlein, C; Jacob, P; Leroy, D; Oberli, L R; Taborelli, M

    2005-01-01

    The LHC superconducting cables are submitted to a 200°C heat-treatment in air in order to increase the resistance between the crossing strands (RC) within the cable. During this treatment the as-applied Sn-Ag alloy strand coating is transformed into a CuSn intermetallic compound layer. The microstructure, the surface topography and the surface chemistry of the non-reacted and reacted coatings have been characterised by different techniques, notably focused ion beam (FIB), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Based on the results obtained by these techniques the different influences that the intermetallics have on RC are discussed. The desired RC is obtained only when a continuous Cu3Sn layer is formed, i.e. a sufficient wetting of the Cu substrate by the tinning alloy is crucial. Among other effects the formation of the comparatively hard intermetallics roughens the surface and, thus, reduces the true contact area and i...

  10. Exploring Culturally Specific Drug Resistance Strategies of Hawaiian Youth in Rural Communities

    Science.gov (United States)

    Okamoto, Scott K.; Po'a-Kekuawela, Ka'ohinani; Chin, Coralee I. H.; Nebre, La Risa H.; Helm, Susana

    2010-01-01

    This qualitative study examined the drug resistance strategies of Hawaiian youth residing in rural communities in Hawai'i. Forty seven youth participated in 14 focus groups which focused on the social and environmental context of drug use for these youth. The findings indicated that there were 47 references to resistance strategies used in drug…

  11. Identification of markers associated with race-specific resistance to Aphanomyces root rot in alfalfa

    Science.gov (United States)

    Aphanomyces root rot, caused by Aphanomyces euteiches, is one of the most important diseases of alfalfa in the United States. Two races of the pathogen are recognized and although most cultivars are resistant to race 1, fewer have resistance to race 2, the predominant race in North America. Molecula...

  12. Obesity, ectopic lipids, and insulin resistance : Tissue-specific defects in nutrient handling

    NARCIS (Netherlands)

    ter Horst, K.W.

    2017-01-01

    This thesis described studies on the clinical, nutritional, and molecular aspects of insulin resistance in human obesity. We investigated methods for the identification of insulin resistance in high-risk patients and studied the nutritional and molecular mechanisms that may contribute to insulin

  13. Identification of Nine Pathotype-Specific Genes Conferring Resistance to Fusiform Rust in Loblolly Pine (Pinus taeda L.

    Directory of Open Access Journals (Sweden)

    Henry V. Amerson

    2015-08-01

    Full Text Available Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for disease development. In particular, nine fusiform rust resistance genes (Fr genes are described here including the specific methods to determine each and their localization on the reference genetic map of loblolly pine. Understanding how these and other apparent Fr genes in loblolly pine and other rust-susceptible pines impact resistance screening, parental and progeny selection, and family and clonal deployment is an important area in forest genetics research and operational tree breeding. The documentation of these Fr genes is a key piece of information towards gaining that understanding and ultimately improving breeding and deployment strategies.

  14. How Specific is Non-Hypersensitive Host and Nonhost Resistance of Barley to Rust and Mildew Fungi?

    NARCIS (Netherlands)

    Niks, R.E.

    2014-01-01

    Full nonhost resistance can be defined as immunity, displayed by an entire plant species against all genotypes of a plant pathogen. Interesting biological questions are, whether the genes responsible for the nonhost status of a plant species have a general or a specific effectiveness to heterologous

  15. Identification of nine pathotype-specific genes conferring resistance to fusiform rust in loblolly pine (Pinus taeda L.)

    Science.gov (United States)

    Henry Amerson; C. Dana Nelson; Thomas L. Kubisiak; E.George Kuhlman; Saul Garcia

    2015-01-01

    Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for disease development. In particular, nine fusiform rust...

  16. Genetic and molecular characterization of leaf rust resistance in two durum landraces against the durum- specific Puccinia triticina races

    Science.gov (United States)

    The Portuguese durum landraces, Aus26582 and Aus26579, showed resistance against two very different durum-specific Puccinia triticina (Pt) races CA 1.2 and ETH 12.5-2 collected from California and Ethiopia, respectively. Aus26582 and Aus26579 were crossed with a susceptible landrace Bansi to develop...

  17. Reliability growth of thin film resistors contact

    Directory of Open Access Journals (Sweden)

    Lugin A. N.

    2010-10-01

    Full Text Available Necessity of resistive layer growth under the contact and in the contact zone of resistive element is shown in order to reduce peak values of current flow and power dissipation in the contact of thin film resistor, thereby to increase the resistor stability to parametric and catastrophic failures.

  18. Electrochemical deposition of buried contacts in high-efficiency crystalline silicon photovoltaic cells

    DEFF Research Database (Denmark)

    Jensen, Jens Arne Dahl; Møller, Per; Bruton, Tim

    2003-01-01

    This article reports on a newly developed method for electrochemical deposition of buried Cu contacts in Si-based photovoltaic ~PV! cells. Contact grooves, 20 mm wide by 40 mm deep, were laser-cut into Si PV cells, hereafter applied with a thin electroless NiP base and subsequently filled with Cu......, with a grain-size decreasing from the center to the edges of the buried Cu contacts and a pronounced lateral growth outside the laser-cut grooves. The measured specific contact resistances of the buried contacts was better than the production standard. Overall performance of the new PV cells was equal...

  19. Strain-Specific Transfer of Antibiotic Resistance from an Environmental Plasmid to Foodborne Pathogens

    Directory of Open Access Journals (Sweden)

    Eva Van Meervenne

    2012-01-01

    Full Text Available Pathogens resistant to multiple antibiotics are rapidly emerging, entailing important consequences for human health. This study investigated if the broad-host-range multiresistance plasmid pB10, isolated from a wastewater treatment plant, harbouring amoxicillin, streptomycin, sulfonamide, and tetracycline resistance genes, was transferable to the foodborne pathogens Salmonella spp. or E. coli O157:H7 and how this transfer alters the phenotype of the recipients. The transfer ratio was determined by both plating and flow cytometry. Antibiotic resistance profiles were determined for both recipients and transconjugants using the disk diffusion method. For 14 of the 15 recipient strains, transconjugants were detected. Based on plating, transfer ratios were between 6.8×10−9 and 3.0×10−2 while using flow cytometry, transfer ratios were between <1.0×10−5 and 1.9×10−2. With a few exceptions, the transconjugants showed phenotypically increased resistance, indicating that most of the transferred resistance genes were expressed. In summary, we showed that an environmental plasmid can be transferred into foodborne pathogenic bacteria at high transfer ratios. However, the transfer ratio seemed to be recipient strain dependent. Moreover, the newly acquired resistance genes could turn antibiotic susceptible strains into resistant ones, paving the way to compromise human health.

  20. Innovation: Contact

    African Journals Online (AJOL)

    Principal Contact. Ruth Hoskins Editor University of KwaZulu-Natal, Information Studies Programme Email: hoskinsr@ukzn.ac.za. Support Contact. Gita Ramdass Email: ramdass@ukzn.ac.za. ISSN: 1025-8892. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

  1. Elicitation of Induced Resistance against Pectobacterium carotovorum and Pseudomonas syringae by Specific Individual Compounds Derived from Native Korean Plant Species

    Directory of Open Access Journals (Sweden)

    Choong-Min Ryu

    2013-10-01

    Full Text Available Plants have developed general and specific defense mechanisms for protection against various enemies. Among the general defenses, induced resistance has distinct characteristics, such as broad-spectrum resistance and long-lasting effectiveness. This study evaluated over 500 specific chemical compounds derived from native Korean plant species to determine whether they triggered induced resistance against Pectobacterium carotovorum supsp. carotovorum (Pcc in tobacco (Nicotiana tabacum and Pseudomonas syringae pv. tomato (Pst in Arabidopsis thaliana. To select target compound(s with direct and indirect (volatile effects, a new Petri-dish-based in vitro disease assay system with four compartments was developed. The screening assay showed that capsaicin, fisetin hydrate, jaceosidin, and farnesiferol A reduced the disease severity significantly in tobacco. Of these four compounds, capsaicin and jaceosidin induced resistance against Pcc and Pst, which depended on both salicylic acid (SA and jasmonic acid (JA signaling, using Arabidopsis transgenic and mutant lines, including npr1 and NahG for SA signaling and jar1 for JA signaling. The upregulation of the PR2 and PDF1.2 genes after Pst challenge with capsaicin pre-treatment indicated that SA and JA signaling were primed. These results demonstrate that capsaicin and jaceosidin can be effective triggers of strong induced resistance against both necrotrophic and biotrophic plant pathogens.

  2. Elicitation of induced resistance against Pectobacterium carotovorum and Pseudomonas syringae by specific individual compounds derived from native Korean plant species.

    Science.gov (United States)

    Song, Geun Cheol; Ryu, Shi Yong; Kim, Young Sup; Lee, Ji Young; Choi, Jung Sup; Ryu, Choong-Min

    2013-10-16

    Plants have developed general and specific defense mechanisms for protection against various enemies. Among the general defenses, induced resistance has distinct characteristics, such as broad-spectrum resistance and long-lasting effectiveness. This study evaluated over 500 specific chemical compounds derived from native Korean plant species to determine whether they triggered induced resistance against Pectobacterium carotovorum supsp. carotovorum (Pcc) in tobacco (Nicotiana tabacum) and Pseudomonas syringae pv. tomato (Pst) in Arabidopsis thaliana. To select target compound(s) with direct and indirect (volatile) effects, a new Petri-dish-based in vitro disease assay system with four compartments was developed. The screening assay showed that capsaicin, fisetin hydrate, jaceosidin, and farnesiferol A reduced the disease severity significantly in tobacco. Of these four compounds, capsaicin and jaceosidin induced resistance against Pcc and Pst, which depended on both salicylic acid (SA) and jasmonic acid (JA) signaling, using Arabidopsis transgenic and mutant lines, including npr1 and NahG for SA signaling and jar1 for JA signaling. The upregulation of the PR2 and PDF1.2 genes after Pst challenge with capsaicin pre-treatment indicated that SA and JA signaling were primed. These results demonstrate that capsaicin and jaceosidin can be effective triggers of strong induced resistance against both necrotrophic and biotrophic plant pathogens.

  3. Resistance to Plasmopara viticola in a grapevine segregating population is associated with stilbenoid accumulation and with specific host transcriptional responses

    Directory of Open Access Journals (Sweden)

    Delledonne Massimo

    2011-08-01

    Full Text Available Abstract Background Downy mildew, caused by the oomycete Plasmopara viticola, is a serious disease in Vitis vinifera, the most commonly cultivated grapevine species. Several wild Vitis species have instead been found to be resistant to this pathogen and have been used as a source to introgress resistance into a V. vinifera background. Stilbenoids represent the major phytoalexins in grapevine, and their toxicity is closely related to the specific compound. The aim of this study was to assess the resistance response to P. viticola of the Merzling × Teroldego cross by profiling the stilbenoid content of the leaves of an entire population and the transcriptome of resistant and susceptible individuals following infection. Results A three-year analysis of the population's response to artificial inoculation showed that individuals were distributed in nine classes ranging from total resistance to total susceptibility. In addition, quantitative metabolite profiling of stilbenoids in the population, carried out using HPLC-DAD-MS, identified three distinct groups differing according to the concentrations present and the complexity of their profiles. The high producers were characterized by the presence of trans-resveratrol, trans-piceid, trans-pterostilbene and up to thirteen different viniferins, nine of them new in grapevine. Accumulation of these compounds is consistent with a resistant phenotype and suggests that they may contribute to the resistance response. A preliminary transcriptional study using cDNA-AFLP selected a set of genes modulated by the oomycete in a resistant genotype. The expression of this set of genes in resistant and susceptible genotypes of the progeny population was then assessed by comparative microarray analysis. A group of 57 genes was found to be exclusively modulated in the resistant genotype suggesting that they are involved in the grapevine-P. viticola incompatible interaction. Functional annotation of these transcripts

  4. Aging causes decreased resistance to multiple stresses and a failure to activate specific stress response pathways

    OpenAIRE

    Dues, Dylan J.; Andrews, Emily K.; Schaar, Claire E.; Bergsma, Alexis L.; Senchuk, Megan M.; Van Raamsdonk, Jeremy M.

    2016-01-01

    In this work, we examine the relationship between stress resistance and aging. We find that resistance to multiple types of stress peaks during early adulthood and then declines with age. To dissect the underlying mechanisms, we use C. elegans transcriptional reporter strains that measure the activation of different stress responses including: the heat shock response, mitochondrial unfolded protein response, endoplasmic reticulum unfolded protein response, hypoxia response, SKN-1-mediated oxi...

  5. Y5U multilayer ceramic capacitors with high-specific capacitance and low-equivalent series resistance.

    Science.gov (United States)

    Ochi, A; Mori, T; Nakanishi, M; Utsumi, K; Abe, S; Yoshimoto, T

    1991-01-01

    A dielectric powder material, for Y5U multilayer ceramic capacitors was developed in the Pb(Mg(1/3)Nb(2/3))O (3)-Pb(Ni(1/3)Nb(2/3))O(3)-PbTiO (3) ternary system by using an alkoxide process. Multilayer ceramic chip capacitors (10 muF) with high specific capacitances were fabricated using this powder. A Ag80%-Pd20% alloy was used for the internal electrodes. The alkoxide-derived capacitor had an extremely high specific capacitance of about 500 muF/cm(3) and a small temperature dependence meeting Y5U specifications of the EIA standard. The equivalent series resistance was approximately 20 mOmega at 500 kHz. The breakdown voltages of the capacitor were 300 V or higher. In accelerated load life tests and load humidity tests, no degradation of insulation resistance was found during 1000 h of testing.

  6. Eggplant Resistance to the Ralstonia solanacearum Species Complex Involves Both Broad-Spectrum and Strain-Specific Quantitative Trait Loci

    Directory of Open Access Journals (Sweden)

    Sylvia Salgon

    2017-05-01

    Full Text Available Bacterial wilt (BW is a major disease of solanaceous crops caused by the Ralstonia solanacearum species complex (RSSC. Strains are grouped into five phylotypes (I, IIA, IIB, III, and IV. Varietal resistance is the most sustainable strategy for managing BW. Nevertheless, breeding to improve cultivar resistance has been limited by the pathogen’s extensive genetic diversity. Identifying the genetic bases of specific and non-specific resistance is a prerequisite to breed improvement. A major gene (ERs1 was previously mapped in eggplant (Solanum melongena L. using an intraspecific population of recombinant inbred lines derived from the cross of susceptible MM738 (S × resistant AG91-25 (R. ERs1 was originally found to control three strains from phylotype I, while being totally ineffective against a virulent strain from the same phylotype. We tested this population against four additional RSSC strains, representing phylotypes I, IIA, IIB, and III in order to clarify the action spectrum of ERs1. We recorded wilting symptoms and bacterial stem colonization under controlled artificial inoculation. We constructed a high-density genetic map of the population using single nucleotide polymorphisms (SNPs developed from genotyping-by-sequencing and added 168 molecular markers [amplified fragment length polymorphisms (AFLPs, simple sequence repeats (SSRs, and sequence-related amplified polymorphisms (SRAPs] developed previously. The new linkage map based on a total of 1,035 markers was anchored on eggplant, tomato, and potato genomes. Quantitative trait locus (QTL mapping for resistance against a total of eight RSSC strains resulted in the detection of one major phylotype-specific QTL and two broad-spectrum QTLs. The major QTL, which specifically controls three phylotype I strains, was located at the bottom of chromosome 9 and corresponded to the previously identified major gene ERs1. Five candidate R-genes were underlying this QTL, with different alleles

  7. Nonimpact of Decolonization as an Adjunctive Measure to Contact Precautions for the Control of Methicillin-Resistant Staphylococcus aureus Transmission in Acute Care.

    Science.gov (United States)

    Peterson, Lance R; Wright, Marc O; Beaumont, Jennifer L; Komutanon, Vanida; Patel, Parul A; Schora, Donna M; Schmitt, Bryan H; Robicsek, Ari

    2016-01-01

    This was an observational study comparing methicillin-resistant Staphylococcus aureus (MRSA) transmission with no decolonization of medical patients to required decolonization of all MRSA carriers during two consecutive periods: baseline with no decolonization of medical patients (16 months) and universal MRSA carrier decolonization (13 months). The setting was a one-hospital, 156-bed facility with 9,200 annual admissions. Regression models were used to compare rates of MRSA acquisition. The chi-square test was used to compare event frequencies. We used rates of MRSA clinical disease as an outcome monitor of the program. Analysis was done on 15,666 patients who had admission and discharge tests; 27.9% of inpatient days were occupied by a MRSA-positive patient (colonized patient-days) who received decolonization while hospitalized during the baseline period (this 27.9% represented those who had planned surgery) compared to 76.0% during the intervention period (P transmission was 97 events (1.0%) for 9,415 admissions (2.0 transmission events/1,000 patient-days) during baseline and was 87 (1.4%) for 6,251 admissions (2.7 transmission events/1,000 patient-days) during intervention (P = 0.06; rate ratio, 0.74; 95% confidence interval [CI], 0.55 to 1.00). The MRSA nosocomial clinical disease rate was 5.9 infections/10,000 patient-days in the baseline period and was 7.2 infections/10,000 patient-days for the intervention period (rate ratio, 0.82; 95% CI, 0.46 to 1.45; P = 0.49). Decolonization of MRSA patients does not add benefit when contact precautions are used for patients colonized with MRSA in acute (hospital) care. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. H3N2v and other influenza epidemic risk based on age-specific estimates of sero-protection and contact network interactions.

    Directory of Open Access Journals (Sweden)

    Danuta M Skowronski

    Full Text Available Cases of a novel swine-origin influenza A(H3N2 variant (H3N2v have recently been identified in the US, primarily among children. We estimated potential epidemic attack rates (ARs based on age-specific estimates of sero-susceptibility and social interactions. A contact network model previously established for the Greater Vancouver Area (GVA, Canada was used to estimate average epidemic (infection ARs for the emerging H3N2v and comparator viruses (H1N1pdm09 and an extinguished H3N2 seasonal strain based on typical influenza characteristics, basic reproduction number (R(0, and effective contacts taking into account age-specific sero-protection rates (SPRs. SPRs were assessed in sera collected from the GVA in 2009 or earlier (pre-H1N1pdm09 and fall 2010 (post-H1N1pdm09, seasonal A/Brisbane/10/2007(H3N2, and H3N2v by hemagglutination inhibition (HI assay. SPR was assigned per convention based on proportion with HI antibody titre ≥40 (SPR40. Recognizing that the HI titre ≥40 was established as the 50%sero-protective threshold we also explored for ½SPR40, SPR80 and a blended gradient defined as: ¼SPR20, ½SPR40, ¾SPR80, SPR160. Base case analysis assumed R(0 = 1.40, but we also explored R(0 as high as 1.80. With R(0 = 1.40 and SPR40, simulated ARs were well aligned with field observations for H1N1pdm09 incidence (AR: 32%, sporadic detections without a third epidemic wave post-H1N1pdm09 (negligible AR<0.1% as well as A/Brisbane/10/2007(H3N2 seasonal strain extinction and antigenic drift replacement (negligible AR<0.1%. Simulated AR for the novel swine-origin H3N2v was 6%, highest in children 6-11years (16%. However, with modification to SPR thresholds per above, H3N2v AR ≥20% became possible. At SPR40, H3N2v AR ≥10%, ≥15% or ≥30%, occur if R(0≥1.48, ≥1.56 or ≥1.86, respectively. Based on conventional assumptions, the novel swine-origin H3N2v does not currently pose a substantial pandemic threat. If H3N2v epidemics do occur

  9. Aging causes decreased resistance to multiple stresses and a failure to activate specific stress response pathways

    Science.gov (United States)

    Bergsma, Alexis L.; Senchuk, Megan M.; Van Raamsdonk, Jeremy M.

    2016-01-01

    In this work, we examine the relationship between stress resistance and aging. We find that resistance to multiple types of stress peaks during early adulthood and then declines with age. To dissect the underlying mechanisms, we use C. elegans transcriptional reporter strains that measure the activation of different stress responses including: the heat shock response, mitochondrial unfolded protein response, endoplasmic reticulum unfolded protein response, hypoxia response, SKN-1-mediated oxidative stress response, and the DAF-16-mediated stress response. We find that the decline in stress resistance with age is at least partially due to a decreased ability to activate protective mechanisms in response to stress. In contrast, we find that any baseline increase in stress caused by the advancing age is too mild to detectably upregulate any of the stress response pathways. Further exploration of how worms respond to stress with increasing age revealed that the ability to mount a hormetic response to heat stress is also lost with increasing age. Overall, this work demonstrates that resistance to all types of stress declines with age. Based on our data, we speculate that the decrease in stress resistance with advancing age results from a genetically-programmed inactivation of stress response pathways, not accumulation of damage. PMID:27053445

  10. Aging causes decreased resistance to multiple stresses and a failure to activate specific stress response pathways.

    Science.gov (United States)

    Dues, Dylan J; Andrews, Emily K; Schaar, Claire E; Bergsma, Alexis L; Senchuk, Megan M; Van Raamsdonk, Jeremy M

    2016-04-01

    In this work, we examine the relationship between stress resistance and aging. We find that resistance to multiple types of stress peaks during early adulthood and then declines with age. To dissect the underlying mechanisms, we use C. elegans transcriptional reporter strains that measure the activation of different stress responses including: the heat shock response, mitochondrial unfolded protein response, endoplasmic reticulum unfolded protein response, hypoxia response, SKN-1-mediated oxidative stress response, and the DAF-16-mediated stress response. We find that the decline in stress resistance with age is at least partially due to a decreased ability to activate protective mechanisms in response to stress. In contrast, we find that any baseline increase in stress caused by the advancing age is too mild to detectably upregulate any of the stress response pathways. Further exploration of how worms respond to stress with increasing age revealed that the ability to mount a hormetic response to heat stress is also lost with increasing age. Overall, this work demonstrates that resistance to all types of stress declines with age. Based on our data, we speculate that the decrease in stress resistance with advancing age results from a genetically-programmed inactivation of stress response pathways, not accumulation of damage.

  11. Contribution of Specific Amino Acid Changes in Penicillin Binding Protein 1 to Amoxicillin Resistance in Clinical Helicobacter pylori isolates ▿

    Science.gov (United States)

    Qureshi, Nadia N.; Morikis, Dimitrios; Schiller, Neal L.

    2011-01-01

    Amoxicillin is commonly used to treat Helicobacter pylori, a major cause of peptic ulcers, stomach cancer, and B-cell mucosa-associated lymphoid tissue lymphoma. Amoxicillin resistance in H. pylori is increasing steadily, especially in developing countries, leading to treatment failures. In this study, we characterize the mechanism of amoxicillin resistance in the U.S. clinical isolate B258. Transformation of amoxicillin-susceptible strain 26695 with the penicillin binding protein 1 gene (pbp1) from B258 increased the amoxicillin resistance of 26695 to equal that of B258, while studies using biotinylated amoxicillin showed a decrease in the binding of amoxicillin to the PBP1 of B258. Transformation with 4 pbp1 fragments, each encompassing several amino acid substitutions, combined with site-directed mutagenesis studies, identified 3 amino acid substitutions in PBP1 of B258 which affected amoxicillin susceptibility (Val 469 Met, Phe 473 Leu, and Ser 543 Arg). Homology modeling showed the spatial orientation of these specific amino acid changes in PBP1 from 26695 and B258. The results of these studies demonstrate that amoxicillin resistance in the clinical U.S. isolate B258 is due solely to an altered PBP1 protein with a lower binding affinity for amoxicillin. Homology modeling analyses using previously identified amino acid substitutions of amoxicillin-resistant PBP1s demonstrate the importance of specific amino acid substitutions in PBP1 that affect the binding of amoxicillin in the putative binding cleft, defining those substitutions deemed most important in amoxicillin resistance. PMID:20956585

  12. Contribution of specific amino acid changes in penicillin binding protein 1 to amoxicillin resistance in clinical Helicobacter pylori isolates.

    Science.gov (United States)

    Qureshi, Nadia N; Morikis, Dimitrios; Schiller, Neal L

    2011-01-01

    Amoxicillin is commonly used to treat Helicobacter pylori, a major cause of peptic ulcers, stomach cancer, and B-cell mucosa-associated lymphoid tissue lymphoma. Amoxicillin resistance in H. pylori is increasing steadily, especially in developing countries, leading to treatment failures. In this study, we characterize the mechanism of amoxicillin resistance in the U.S. clinical isolate B258. Transformation of amoxicillin-susceptible strain 26695 with the penicillin binding protein 1 gene (pbp1) from B258 increased the amoxicillin resistance of 26695 to equal that of B258, while studies using biotinylated amoxicillin showed a decrease in the binding of amoxicillin to the PBP1 of B258. Transformation with 4 pbp1 fragments, each encompassing several amino acid substitutions, combined with site-directed mutagenesis studies, identified 3 amino acid substitutions in PBP1 of B258 which affected amoxicillin susceptibility (Val 469 Met, Phe 473 Leu, and Ser 543 Arg). Homology modeling showed the spatial orientation of these specific amino acid changes in PBP1 from 26695 and B258. The results of these studies demonstrate that amoxicillin resistance in the clinical U.S. isolate B258 is due solely to an altered PBP1 protein with a lower binding affinity for amoxicillin. Homology modeling analyses using previously identified amino acid substitutions of amoxicillin-resistant PBP1s demonstrate the importance of specific amino acid substitutions in PBP1 that affect the binding of amoxicillin in the putative binding cleft, defining those substitutions deemed most important in amoxicillin resistance.

  13. Sex-specific effect of juvenile diet on adult disease resistance in a field cricket.

    Directory of Open Access Journals (Sweden)

    Clint D Kelly

    Full Text Available Food limitation is expected to reduce an individual's body condition (body mass scaled to body size and cause a trade-off between growth and other fitness-related traits, such as immunity. We tested the condition-dependence of growth and disease resistance in male and female Gryllus texensis field crickets by manipulating diet quality via nutrient content for their entire life and then subjecting individuals to a host resistance test using the live bacterium Serratia marcescens. As predicted, crickets on a high-quality diet eclosed more quickly, and at a larger body size and mass. Crickets on a high-quality diet were not in better condition at the time of eclosion, but they were in better condition 7-11 days after eclosion, with females also being in better condition than males. Despite being in better condition, however, females provided with a high-quality diet had significantly poorer disease resistance than females on a low-quality diet and in poor condition. Similarly, males on low- and high-quality diets did not differ in their disease resistance, despite differing in their body condition. A sex difference in disease resistance under diet-restriction suggests that females might allocate resources toward immunity during development if they expect harsh environmental conditions as an adult or it might suggest that females allocate resources toward other life history activities (i.e. reproduction when food availability increases. We do not know what immune effectors were altered under diet-restriction to increase disease resistance, but our findings suggest that increased immune function might provide an explanation for the sexually-dimorphic increase in longevity generally observed in diet-restricted animals.

  14. Escherichia coli ASKA Clone Library Harboring tRNA-Specific Adenosine Deaminase (tadA Reveals Resistance towards Xanthorrhizol

    Directory of Open Access Journals (Sweden)

    Yogiara

    2015-09-01

    Full Text Available Xanthorrhizol is a potent antimicrobial compound isolated from the rhizome of Curcuma xanthorrhiza. However, the mechanism of xanthorrhizol action is unknown. To screen for probable target(s, we introduced the ASKA pooled-plasmid library into Escherichia coli W3110 imp4213 and enriched the library for resistant clones with increasing concentrations of xanthorrhizol. After three rounds of enrichment, we found nine genes that increased xanthorrhizol resistance. The resistant clones were able to grow in LB medium containing 256 µg/mL xanthorrhizol, representing a 16-fold increase in the minimum inhibitory concentration. Subsequent DNA sequence analysis revealed that overexpression of tadA, galU, fucU, ydeA, ydaC, soxS, nrdH, yiiD, and mltF genes conferred increased resistance towards xanthorrhizol. Among these nine genes, tadA is the only essential gene. tadA encodes a tRNA-specific adenosine deaminase. Overexpression of E. coli W3110 imp4213 (pCA24N-tadA conferred resistance to xanthorrhizol up to 128 µg/mL. Moreover, overexpression of two tadA mutant enzymes (A143V and F149G led to a twofold increase in the MIC. These results suggest that the targets of xanthorrhizol may include tadA, which has never before been explored as an antibiotic target.

  15. Effect of a specific exercise program on the strength and resistance levels of lumbar muscles in warehouse workers.

    Science.gov (United States)

    Carvalho Mesquita, Cristina; Ribeiro, José Carlos; Moreira, Pedro

    2012-03-01

    The aim of this study was to verify the influence of a specific exercise program on the strength and resistance levels of lumbar flexors and extensors in warehouse workers. The population used in this randomized controlled trial included 557 warehouse male workers from a food distribution company in Oporto/Portugal. Upon the application of the selection criteria, 98 workers deemed eligible were randomized in two groups: 57 were assigned to the intervention group and 41 to the control group. The intervention included 9 easily-executed exercises to promote stretching and strengthening of the lumbar region, to be executed daily, at the beginning of the working time, at the company facilities and lasting 8'. Trunk muscles' voluntary strength and resistance were measured using an isometric electronic dynamometer (Globus Ergometer, Globus, Codigné, Italy) at baseline and eleven months after implementing the exercise program. The data was analyzed using SPSS®, version 17.0. After implementation of the exercise program, in the intervention group, all variables increased, significant differences were observed as for the muscle strength and resistance values (p = 0.014 and p = 0.006, respectively), as well as in the ratio extensors/flexors (p = 0.037). In the control group, all variables decreased, with a statistically significant decrease of the trunk flexors strength level (p = 0.009). The results of this study suggest that a specific exercise intervention program can increase trunk extensors strength and resistance.

  16. Specificity and levels of nonhost resistance to nonadapted Blumeria graminis forms in barley

    NARCIS (Netherlands)

    Aghnoum, R.; Niks, R.E.

    2010-01-01

    • The genetic basis of nonhost resistance of barley to nonadapted formae speciales of Blumeria graminis is not known, as there is no barley line that is susceptible to these nonadapted formae speciales, such as the wheat powdery mildew pathogen, Blumeria graminis f.sp. tritici (Bgt). • Barley

  17. Contextualizing Intergroup Contact: Do Political Party Cues Enhance Contact Effects?

    DEFF Research Database (Denmark)

    Sønderskov, Kim Mannemar; Thomsen, Jens Peter Frølund

    2015-01-01

    This article examines intergroup contact effects in different political contexts. We expand on previous efforts of social psychologists by incorporating the messages of political parties as a contextual trigger of group membership awareness in contact situations. We argue that the focus among......,000 individuals confirms that the ability of intergroup contact to reduce antiforeigner sentiment increases when political parties focus intensively on immigration issues and cultural differences. Specifically, both workplace contact and interethnic friendship become more effective in reducing antiforeigner...

  18. On a two-layer Si{sub 3}N{sub 4}/SiO{sub 2} dielectric mask for low-resistance ohmic contacts to AlGaN/GaN HEMTs

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunyan, S. S., E-mail: spartakmain@gmail.com; Pavlov, A. Yu.; Pavlov, B. Yu.; Tomosh, K. N.; Fedorov, Yu. V. [Russian Academy of Sciences, Institute of Ultrahigh Frequency Semiconductor Electronics (Russian Federation)

    2016-08-15

    The fabrication of a two-layer Si{sub 3}N{sub 4}/SiO{sub 2} dielectric mask and features of its application in the technology of non-fired epitaxially grown ohmic contacts for high-power HEMTs on AlGaN/GaN heterostructures are described. The proposed Si{sub 3}N{sub 4}/SiO{sub 2} mask allows the selective epitaxial growth of heavily doped ohmic contacts by nitride molecular-beam epitaxy and the fabrication of non-fired ohmic contacts with a resistance of 0.15–0.2 Ω mm and a smooth surface and edge morphology.

  19. Antibiotics and Resistance: Glossary

    Science.gov (United States)

    ... Work Contact Us ABOUT THE ISSUE What is Antibiotic Resistance? General Background Science of Resistance Glossary References ... for Adaptation Genetics and Drug Resistance Reservoirs of Antibiotic Resistance Project (ROAR) INTERNATIONAL CHAPTERS APUA Chapter Network ...

  20. Enhanced virus resistance in transgenic maize expressing a dsRNA-specific endoribonuclease gene from E. coli.

    Science.gov (United States)

    Cao, Xiuling; Lu, Yingui; Di, Dianping; Zhang, Zhiyan; Liu, He; Tian, Lanzhi; Zhang, Aihong; Zhang, Yanjing; Shi, Lindan; Guo, Bihong; Xu, Jin; Duan, Xifei; Wang, Xianbing; Han, Chenggui; Miao, Hongqin; Yu, Jialin; Li, Dawei

    2013-01-01

    Maize rough dwarf disease (MRDD), caused by several Fijiviruses in the family Reoviridae, is a global disease that is responsible for substantial yield losses in maize. Although some maize germplasm have low levels of polygenic resistance to MRDD, highly resistant cultivated varieties are not available for agronomic field production in China. In this work, we have generated transgenic maize lines that constitutively express rnc70, a mutant E. coli dsRNA-specific endoribonuclease gene. Transgenic lines were propagated and screened under field conditions for 12 generations. During three years of evaluations, two transgenic lines and their progeny were challenged with Rice black-streaked dwarf virus (RBSDV), the causal agent of MRDD in China, and these plants exhibited reduced levels of disease severity. In two normal years of MRDD abundance, both lines were more resistant than non-transgenic plants. Even in the most serious MRDD year, six out of seven progeny from one line were resistant, whereas non-transgenic plants were highly susceptible. Molecular approaches in the T12 generation revealed that the rnc70 transgene was integrated and expressed stably in transgenic lines. Under artificial conditions permitting heavy virus inoculation, the T12 progeny of two highly resistant lines had a reduced incidence of MRDD and accumulation of RBSDV in infected plants. In addition, we confirmed that the RNC70 protein could bind directly to RBSDV dsRNA in vitro. Overall, our data show that RNC70-mediated resistance in transgenic maize can provide efficient protection against dsRNA virus infection.

  1. Enhanced virus resistance in transgenic maize expressing a dsRNA-specific endoribonuclease gene from E. coli.

    Directory of Open Access Journals (Sweden)

    Xiuling Cao

    Full Text Available Maize rough dwarf disease (MRDD, caused by several Fijiviruses in the family Reoviridae, is a global disease that is responsible for substantial yield losses in maize. Although some maize germplasm have low levels of polygenic resistance to MRDD, highly resistant cultivated varieties are not available for agronomic field production in China. In this work, we have generated transgenic maize lines that constitutively express rnc70, a mutant E. coli dsRNA-specific endoribonuclease gene. Transgenic lines were propagated and screened under field conditions for 12 generations. During three years of evaluations, two transgenic lines and their progeny were challenged with Rice black-streaked dwarf virus (RBSDV, the causal agent of MRDD in China, and these plants exhibited reduced levels of disease severity. In two normal years of MRDD abundance, both lines were more resistant than non-transgenic plants. Even in the most serious MRDD year, six out of seven progeny from one line were resistant, whereas non-transgenic plants were highly susceptible. Molecular approaches in the T12 generation revealed that the rnc70 transgene was integrated and expressed stably in transgenic lines. Under artificial conditions permitting heavy virus inoculation, the T12 progeny of two highly resistant lines had a reduced incidence of MRDD and accumulation of RBSDV in infected plants. In addition, we confirmed that the RNC70 protein could bind directly to RBSDV dsRNA in vitro. Overall, our data show that RNC70-mediated resistance in transgenic maize can provide efficient protection against dsRNA virus infection.

  2. Sensitivity, specificity and predictive value of modified assays for activated protein C resistance in children.

    Science.gov (United States)

    Brandt, G; Gruppo, R; Glueck, C J; Stroop, D; Becker, A; Pillow, A; Wang, P

    1998-03-01

    Very little data is available assessing the clinical utility of coagulation-based APC resistance assays compared to DNA-based analysis for the factor V Leiden mutation in children. Therefore, the clinical utility of four aPTT-based assays for APC resistance was evaluated in 169 children, ages 3 months through 16 years. The prevalence of the Arg506 to Gln mutation was 7/169 (4.1%). Using cutoff points derived from the normal PCR-screened population (n = 162), two assays for APC resistance (APC-SR and n-APC-SR) gave poor concordance with the PCR assay (sensitivity 29% and 57%, respectively). Two modified assays (FDAPC-SR and n-FDAPC-SR), in which patient plasma was prediluted 1:5 in factor V deficient plasma, gave excellent concordance (sensitivity 100%). The predictive value of a positive test was 0.25, 0.44, 1.00 and 0.88 for the APC-SR, n-APC-SR, FDAPC-SR and n-FDAPC-SR, respectively. The FDAPC-SR and n-FDAPC-SR tests gave excellent discrimination using cutoff values derived from the total population (n = 169) without regard to previous PCR screening results.

  3. Detection of mutations related to drug resistance in M. tuberculosis by dot blot hybridization and spoligotyping using specific radiolabelled probes

    International Nuclear Information System (INIS)

    El-Maghraby, T.K.; Abdelazeim, O.

    2002-01-01

    The present work has been conducted to determine the mutations related to drug resistance in M. tuberculosis in 63 Egyptian isolates using dot blot hybridization and spoligotyping. The PCR was done for amplification rpoB and katG genes in isolates. Dot blot hybridization were done to PCR products by using specific radiolabelled probes. Moreover, spoligotyping was done to know about the different strains found in Egypt. The results revealed that 58% from isolates had drug resistance to one or more of antituberculosis drugs. The results of spoligotyping have revealed that some Egyptian isolates are identical with the international code while the rest has not been identified yet. DNA sequencing was done to identify the mutation that not clear in dot blot hybridization. Early diagnosis of geno typing resistance to antituberculosis drugs is important as well as allow appropriate early patients management with few days of TB diagnosis. Using such strategy for early diagnosis of TB drug resistance allow and fast and potent patient's management

  4. Engineering HIV-resistant human CD4+ T cells with CXCR4-specific zinc-finger nucleases.

    Directory of Open Access Journals (Sweden)

    Craig B Wilen

    2011-04-01

    Full Text Available HIV-1 entry requires the cell surface expression of CD4 and either the CCR5 or CXCR4 coreceptors on host cells. Individuals homozygous for the ccr5Δ32 polymorphism do not express CCR5 and are protected from infection by CCR5-tropic (R5 virus strains. As an approach to inactivating CCR5, we introduced CCR5-specific zinc-finger nucleases into human CD4+ T cells prior to adoptive transfer, but the need to protect cells from virus strains that use CXCR4 (X4 in place of or in addition to CCR5 (R5X4 remains. Here we describe engineering a pair of zinc finger nucleases that, when introduced into human T cells, efficiently disrupt cxcr4 by cleavage and error-prone non-homologous DNA end-joining. The resulting cells proliferated normally and were resistant to infection by X4-tropic HIV-1 strains. CXCR4 could also be inactivated in ccr5Δ32 CD4+ T cells, and we show that such cells were resistant to all strains of HIV-1 tested. Loss of CXCR4 also provided protection from X4 HIV-1 in a humanized mouse model, though this protection was lost over time due to the emergence of R5-tropic viral mutants. These data suggest that CXCR4-specific ZFNs may prove useful in establishing resistance to CXCR4-tropic HIV for autologous transplant in HIV-infected individuals.

  5. Overexpression of a defensin enhances resistance to a fruit-specific anthracnose fungus in pepper.

    Directory of Open Access Journals (Sweden)

    Hyo-Hyoun Seo

    Full Text Available Functional characterization of a defensin, J1-1, was conducted to evaluate its biotechnological potentiality in transgenic pepper plants against the causal agent of anthracnose disease, Colletotrichum gloeosporioides. To determine antifungal activity, J1-1 recombinant protein was generated and tested for the activity against C. gloeosporioides, resulting in 50% inhibition of fungal growth at a protein concentration of 0.1 mg·mL-1. To develop transgenic pepper plants resistant to anthracnose disease, J1-1 cDNA under the control of 35S promoter was introduced into pepper via Agrobacterium-mediated genetic transformation method. Southern and Northern blot analyses confirmed that a single copy of the transgene in selected transgenic plants was normally expressed and also stably transmitted to subsequent generations. The insertion of T-DNA was further analyzed in three independent homozygous lines using inverse PCR, and confirmed the integration of transgene in non-coding region of genomic DNA. Immunoblot results showed that the level of J1-1 proteins, which was not normally accumulated in unripe fruits, accumulated high in transgenic plants but appeared to differ among transgenic lines. Moreover, the expression of jasmonic acid-biosynthetic genes and pathogenesis-related genes were up-regulated in the transgenic lines, which is co-related with the resistance of J1-1 transgenic plants to anthracnose disease. Consequently, the constitutive expression of J1-1 in transgenic pepper plants provided strong resistance to the anthracnose fungus that was associated with highly reduced lesion formation and fungal colonization. These results implied the significance of the antifungal protein, J1-1, as a useful agronomic trait to control fungal disease.

  6. Detailed mutational analysis of Vga(A) interdomain linker: Implication for antibiotic resistance specificity and mechanism

    Czech Academy of Sciences Publication Activity Database

    Lenart, Jakub; Vimberg, Vladimír; Veselá, Ludmila; Janata, Jiří; Balíková Novotná, Gabriela

    2015-01-01

    Roč. 59, č. 2 (2015), s. 1360-1364 ISSN 0066-4804 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) EE2.3.20.0055; GA MŠk(CZ) EE2.3.30.0003; GA ČR GPP302/12/P632 Institutional support: RVO:61388971 Keywords : antibiotic * resistance * Vga(A) Subject RIV: EE - Microbiology, Virology Impact factor: 4.415, year: 2015

  7. Hepatocyte-specific deletion of the keap1 gene activates Nrf2 and confers potent resistance against acute drug toxicity

    International Nuclear Information System (INIS)

    Okawa, Hiromi; Motohashi, Hozumi; Kobayashi, Akira; Aburatani, Hiroyuki; Kensler, Thomas W.; Yamamoto, Masayuki

    2006-01-01

    Nrf2 is a key regulator of many detoxifying enzyme genes, and cytoplasmic protein Keap1 represses the Nrf2 activity under quiescent conditions. Germ line deletion of the keap1 gene results in constitutive activation of Nrf2, but the pups unexpectedly died before weaning. To investigate how constitutive activation of Nrf2 influences the detoxification system in adult mice, we generated mice bearing a hepatocyte-specific disruption of the keap1 gene. Homozygous mice were viable and their livers displayed no apparent abnormalities, but nuclear accumulation of Nrf2 is elevated. Microarray analysis revealed that, while many detoxifying enzyme genes are highly expressed, some of the typical Nrf2-dependent genes are only marginally increased in the Keap1-deficient liver. The mutant mice were significantly more resistant to toxic doses of acetaminophen than control animals. These results demonstrate that chronic activation of Nrf2 confers animals with resistance to xenobiotics without affecting the morphological and physiological integrity of hepatocytes

  8. Issues of contact etching and pre-treatment in Schottky contact

    International Nuclear Information System (INIS)

    Lee, Haksun; Shin, Kyoungsub; Cho, Nammyun; Min, Gyungjin; Kang, Changjin; Han, Woosung; Moon, Jootae

    2009-01-01

    This paper reports on the process dependence of contact resistance of silicide/n+ Si and silicide/p+ Si contact. Three processes such as contact etching, Si treatment and pre-treatment are investigated with contact resistance point of view. Only silicide/p+ Si contact resistance has been changed as etching time of contact increases while silicide/n+ Si contact resistance has been regularly maintained. We have modeled that fluorine used in contact etching can scavenge or deactivate boron in p+ Si, resulting in degradation of silicide/p+ Si contact resistance. In order to confirm the model, two different gases (hydro carbon fluoride/carbon fluoride) during Si treatment right after contact etching were applied. As a result, the silicide/p+ Si contact resistance was increased in carbon fluoride case, which has higher fluorine ratio to carbon than hydro carbon fluoride case. It is also observed that the silicide/p+ Si contact resistance was increased proportionally with time of fluorine-based pre-treatment before silicide formation.

  9. Contact hysteroscopy.

    Science.gov (United States)

    Baggish, M S; Barbot, J

    1983-06-01

    In 1907 innovations in optics and illumination made by Maximilian Nitze were applied to hysteroscopy by Charles David, who wrote a treatise of hysteroscopy. David improved illumination by placing an electric incandescent bulb at the intrauterine end of his endoscope and also sealed the distal end of the tube with a piece of glass. The history of the contact endoscope that the authors personally used is connected to the invention by Vulmiere (1952) of a revolutionary illumination process in endoscopy--the "cold light" process. The components of cold light consist of a powerful external light source that is transmitted via a special optical guide into the endometrial cavity. The 1st application of his principle (1963) was an optical trochar contained in a metallic sheath. This simple endoscope was perfected, and in 1973 Barbot and Parent, in France, began to use it to examine the uterine cavity. Discussion focuses on methods, instrumentation, method for examination (grasping the instrument, setup, light source, anesthesia, dilatation, technique, and normal endometrium); cervical neoplasia; nonneoplastic lesions of the endometrium (endometrial polyp, submucous myoma, endometrial hyperplasia); intrauterine device localization; neoplastic lesions of the endometrium; precursors (adenocarcinoma); hysteroscopy in pregnancy (embryoscopy, hydatidiform mole, postpartum hemorrhage, incomplete abortion, spontaneous abortion, induced abortions, and amnioscopy); and examinations of children and infants. The contact endoscope must make light contact with the structure to be viewed. The principles of contact endoscopy depend on an interpretation of color, contour, vascular pattern, and a sense of touch. These are computed together and a diagnosis is made on the basis of previously learned clinical pathologic correlations. The contact endoscope is composed of 3 parts: an optical guide; a cylindric chamber that collects and traps ambient light; and a magnifying eyepiece. The phase of

  10. Dual ohmic contact to N- and P-type silicon carbide

    Science.gov (United States)

    Okojie, Robert S. (Inventor)

    2013-01-01

    Simultaneous formation of electrical ohmic contacts to silicon carbide (SiC) semiconductor having donor and acceptor impurities (n- and p-type doping, respectively) is disclosed. The innovation provides for ohmic contacts formed on SiC layers having n- and p-doping at one process step during the fabrication of the semiconductor device. Further, the innovation provides a non-discriminatory, universal ohmic contact to both n- and p-type SiC, enhancing reliability of the specific contact resistivity when operated at temperatures in excess of 600.degree. C.

  11. Arabidopsis flower specific defense gene expression patterns affect resistance to pathogens

    KAUST Repository

    Ederli, Luisa

    2015-02-20

    We investigated whether the Arabidopsis flower evolved protective measures to increase reproductive success. Firstly, analyses of available transcriptome data show that the most highly expressed transcripts in the closed sepal (stage 12) are enriched in genes with roles in responses to chemical stimuli and cellular metabolic processes. At stage 15, there is enrichment in transcripts with a role in responses to biotic stimuli. Comparative analyses between the sepal and petal in the open flower mark an over-representation of transcripts with a role in responses to stress and catalytic activity. Secondly, the content of the biotic defense-associated phytohormone salicylic acid (SA) in sepals and petals is significantly higher than in leaves. To understand whether the high levels of stress responsive transcripts and the higher SA content affect defense, wild-type plants (Col-0) and transgenic plants defective in SA accumulation (nahG) were challenged with the biotrophic fungus Golovinomyces cichoracearum, the causal agent of powdery mildew, and the necrotrophic fungus Botrytis cinerea. NahG leaves were more sensitive than those of Col-0, suggesting that in leaves SA has a role in the defense against biotrophs. In contrast, sepals and petals of both genotypes were resistant to G. cichoracearum, indicating that in the flower, resistance to the biotrophic pathogen is not critically dependent on SA, but likely dependent on the up-regulation of stress-responsive genes. Since sepals and petals of both genotypes are equally susceptible to B. cinerea, we conclude that neither stress-response genes nor increased SA accumulation offers protection against the necrotrophic pathogen. These results are interpreted in the light of the distinctive role of the flower and we propose that in the early stages, the sepal may act as a chemical defense barrier of the developing reproductive structures against biotrophic pathogens.

  12. Time-wise change in neck pain in response to rehabilitation with specific resistance training: implications for exercise prescription.

    Science.gov (United States)

    Zebis, Mette K; Andersen, Christoffer H; Sundstrup, Emil; Pedersen, Mogens T; Sjøgaard, Gisela; Andersen, Lars L

    2014-01-01

    To determine the time-wise effect of specific resistance training on neck pain among industrial technicians with frequent neck pain symptoms. Secondary analysis of a parallel-group cluster randomized controlled trial of 20 weeks performed at two large industrial production units in Copenhagen, Denmark. Women with neck pain >30 mm VAS (N = 131) were included in the present analysis. The training group (N = 77) performed specific resistance training for the neck/shoulder muscles three times a week, and the control group (N = 54) received advice to stay active. Participants of both groups registered neck pain intensity (0-100 mm VAS) once a week. Neck pain intensity was 55 mm (SD 23) at baseline. There was a significant group by time interaction for neck pain (F-value 2.61, Pchange in pain showed three phases; a rapid decrease in the training group compared with the control group during the initial 7 weeks, a slower decrease in pain during the following weeks (week 8-15), and a plateau during the last weeks (week 16-20). Adherence to training followed a two-phase pattern, i.e. weekly participation rate was between 70-86% during the initial 7 weeks, dropping towards 55-63% during the latter half of the training period. Four weeks of specific resistance training reduced neck pain significantly, but 15 weeks is required to achieve maximal pain reduction. The time-wise change in pain followed a three-phase pattern with a rapid effect during the initial 7 weeks followed by a slower but still positive effect, and finally a plateau from week 15 and onwards. Decreased participation rate may explain the decreased efficacy during the latter phase of the intervention.

  13. Farm-specific lineages of methicillin-resistant Staphyloccus aureus clonal complex 398 in Danish pig farms

    DEFF Research Database (Denmark)

    Espinosa-Gongora, Carmen; Larsen, J.; Moodley, Arshnee

    2012-01-01

    The objective of this study was to investigate the genetic diversity of methicillin-resistant Staphylococcus aureus (MRSA) clonal complex (CC) 398 using pulsed-field gel electrophoresis (PFGE). Dust and pigs at five age groups were sampled in six Danish MRSA-positive pig farms. MRSA CC398...... was isolated from 284 of the 391 samples tested, including 230 (74%) animal and 54 (68%) environmental samples. PFGE analysis of a subset of 48 isolates, including the six strains previously isolated from farm workers, revealed the existence of farm-specific pulsotypes. With a single exception, human...

  14. Geographically Distinct and Domain-Specific Sequence Variations in the Alleles of Rice Blast Resistance Gene Pib.

    Science.gov (United States)

    Vasudevan, Kumar; Vera Cruz, Casiana M; Gruissem, Wilhelm; Bhullar, Navreet K

    2016-01-01

    Rice blast is caused by Magnaporthe oryzae, which is the most destructive fungal pathogen affecting rice growing regions worldwide. The rice blast resistance gene Pib confers broad-spectrum resistance against Southeast Asian M. oryzae races. We investigated the allelic diversity of Pib in rice germplasm originating from 12 major rice growing countries. Twenty-five new Pib alleles were identified that have unique single nucleotide polymorphisms (SNPs), insertions and/or deletions, in addition to the polymorphic nucleotides that are shared between the different alleles. These partially or completely shared polymorphic nucleotides indicate frequent sequence exchange events between the Pib alleles. In some of the new Pib alleles, nucleotide diversity is high in the LRR domain, whereas, in others it is distributed among the NB-ARC and LRR domains. Most of the polymorphic amino acids in LRR and NB-ARC2 domains are predicted as solvent-exposed. Several of the alleles and the unique SNPs are country specific, suggesting a diversifying selection of alleles in various geographical locations in response to the locally prevalent M. oryzae population. Together, the new Pib alleles are an important genetic resource for rice blast resistance breeding programs and provide new information on rice-M. oryzae interactions at the molecular level.

  15. TarO-specific inhibitors of wall teichoic acid biosynthesis restore β-lactam efficacy against methicillin-resistant staphylococci.

    Science.gov (United States)

    Lee, Sang Ho; Wang, Hao; Labroli, Marc; Koseoglu, Sandra; Zuck, Paul; Mayhood, Todd; Gill, Charles; Mann, Paul; Sher, Xinwei; Ha, Sookhee; Yang, Shu-Wei; Mandal, Mihir; Yang, Christine; Liang, Lianzhu; Tan, Zheng; Tawa, Paul; Hou, Yan; Kuvelkar, Reshma; DeVito, Kristine; Wen, Xiujuan; Xiao, Jing; Batchlett, Michelle; Balibar, Carl J; Liu, Jenny; Xiao, Jianying; Murgolo, Nicholas; Garlisi, Charles G; Sheth, Payal R; Flattery, Amy; Su, Jing; Tan, Christopher; Roemer, Terry

    2016-03-09

    The widespread emergence of methicillin-resistant Staphylococcus aureus (MRSA) has dramatically eroded the efficacy of current β-lactam antibiotics and created an urgent need for new treatment options. We report an S. aureus phenotypic screening strategy involving chemical suppression of the growth inhibitory consequences of depleting late-stage wall teichoic acid biosynthesis. This enabled us to identify early-stage pathway-specific inhibitors of wall teichoic acid biosynthesis predicted to be chemically synergistic with β-lactams. We demonstrated by genetic and biochemical means that each of the new chemical series discovered, herein named tarocin A and tarocin B, inhibited the first step in wall teichoic acid biosynthesis (TarO). Tarocins do not have intrinsic bioactivity but rather demonstrated potent bactericidal synergy in combination with broad-spectrum β-lactam antibiotics against diverse clinical isolates of methicillin-resistant staphylococci as well as robust efficacy in a murine infection model of MRSA. Tarocins and other inhibitors of wall teichoic acid biosynthesis may provide a rational strategy to develop Gram-positive bactericidal β-lactam combination agents active against methicillin-resistant staphylococci. Copyright © 2016, American Association for the Advancement of Science.

  16. Differential microRNA expression signatures and cell type-specific association with Taxol resistance in ovarian cancer cells.

    Science.gov (United States)

    Kim, Yong-Wan; Kim, Eun Young; Jeon, Doin; Liu, Juinn-Lin; Kim, Helena Suhyun; Choi, Jin Woo; Ahn, Woong Shick

    2014-01-01

    Paclitaxel (Taxol) resistance remains a major obstacle for the successful treatment of ovarian cancer. MicroRNAs (miRNAs) have oncogenic and tumor suppressor activity and are associated with poor prognosis phenotypes. miRNA screenings for this drug resistance are needed to estimate the prognosis of the disease and find better drug targets. miRNAs that were differentially expressed in Taxol-resistant ovarian cancer cells, compared with Taxol-sensitive cells, were screened by Illumina Human MicroRNA Expression BeadChips. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to identify target genes of selected miRNAs. Kaplan-Meier survival analysis was applied to identify dysregulated miRNAs in ovarian cancer patients using data from The Cancer Genome Atlas. A total of 82 miRNAs were identified in ovarian carcinoma cells compared to normal ovarian cells. miR-141, miR-106a, miR-200c, miR-96, and miR-378 were overexpressed, and miR-411, miR-432, miR-494, miR-409-3p, and miR-655 were underexpressed in ovarian cancer cells. Seventeen miRNAs were overexpressed in Taxol-resistant cells, including miR-663, miR-622, and HS_188. Underexpressed miRNAs in Taxol-sensitive cells included miR-497, miR-187, miR-195, and miR-107. We further showed miR-663 and miR-622 as significant prognosis markers of the chemo-resistant patient group. In particular, the downregulation of the two miRNAs was associated with better survival, perhaps increasing the sensitivity of cancer cells to Taxol. In the chemo-sensitive patient group, only miR-647 could be a prognosis marker. These miRNAs inhibit several interacting genes of p53 networks, especially in TUOS-3 and TUOS-4, and showed cell line-specific inhibition effects. Taken together, the data indicate that the three miRNAs are closely associated with Taxol resistance and potentially better prognosis factors. Our results suggest that these miRNAs were successfully and reliably identified and would be used in the

  17. Coho salmon Oncorhynchus kisutch strain differences in disease resistance and non-specific immunity, following immersion challenges with Vibrio anguillarum

    Science.gov (United States)

    Balfry, Shannon K.; Maule, Alec G.; Iwama, George K.

    2001-01-01

    Two strains of freshwater-reared coho salmon Oncorhynchus kisutch were compared for differences in the activity of selected non-specific immune factors before and after lethal and non-lethal immersion challenges with the marine bacterial pathogen Vibrio anguillarum (Vang). Two disease challenge experiments were performed. The first experimental challenge resulted in no mortality; however, significant strain and challenge treatment effects were detected at Day 16 post-challenge. Strain differences in plasma lysozyme activity were found in pre-challenge samples. The second challenge experiment compared the same strains of coho salmon following immersion challenges in different doses of Vang. The fish were sampled at Days 0, 2, 7, and 18 post-challenge and mortality, plasma lysozyme, and anterior kidney phagocyte respiratory burst activity were compared. There were significant strain differences in mortality in the high dose group. The more disease-resistant strain was found to have higher levels of plasma lysozyme and anterior kidney phagocyte respiratory burst activity. These strain differences were detected at various times in the lethal (high dose) and non-lethal challenge groups. There was a clear relationship between the enhanced survival of the more disease-resistant strain and a more sustained, elevated non-specific immune response following the experimental disease challenges. The results of this study suggest that the basis for strain differences in innate disease resistance is related to the ability of the fish to respond quickly to the initial infection and to maintain the response until the infection is quelled.

  18. Profiling of gender-specific rat plasma proteins associated with susceptibility or resistance to diet-induced obesity.

    Science.gov (United States)

    Choi, Jung-Won; Liu, Hao; Choi, Duk Kwon; Oh, Tae Seok; Mukherjee, Rajib; Yun, Jong Won

    2012-02-02

    Obesity-prone (OP) and obesity-resistant (OR) rats with different responses to development of obesity in spite of the same genetic background are useful animal models for searching for markers during the development of obesity. Here, we investigated whether plasma proteins of OP and OR rats may behave in a different way in males and females. We performed a comparative proteomic analysis using 2-DE combined with MALDI-TOF/MS on proteins from OP and OR male and female rats to discover gender-specific rat plasma proteins associated with susceptibility or resistance to diet-induced obesity. A total of 29 proteins showing differential expression between the groups were identified by MALDI-TOF/MS and database searches. These proteins were classified into 4 groups according to their regulation patterns in response to diet and gender. 22 proteins showed significant differences between OP and OR rats in males and/or females (Group I, II, and III) and 7 proteins exhibited only a high fat diet (HFD)-responsive difference in male or female rats (Group IV). In conclusion, the proteins negatively (ITIH3, FGG, TUBB5, and ZAG) or positively (Hp, ITIH4, and RBP) correlated with obesity found in this study could be used for selection of new targets for gender specific-medical treatment of obesity. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. A patient-specific computational model of hypoxia-modulated radiation resistance in glioblastoma using 18F-FMISO-PET.

    Science.gov (United States)

    Rockne, Russell C; Trister, Andrew D; Jacobs, Joshua; Hawkins-Daarud, Andrea J; Neal, Maxwell L; Hendrickson, Kristi; Mrugala, Maciej M; Rockhill, Jason K; Kinahan, Paul; Krohn, Kenneth A; Swanson, Kristin R

    2015-02-06

    Glioblastoma multiforme (GBM) is a highly invasive primary brain tumour that has poor prognosis despite aggressive treatment. A hallmark of these tumours is diffuse invasion into the surrounding brain, necessitating a multi-modal treatment approach, including surgery, radiation and chemotherapy. We have previously demonstrated the ability of our model to predict radiographic response immediately following radiation therapy in individual GBM patients using a simplified geometry of the brain and theoretical radiation dose. Using only two pre-treatment magnetic resonance imaging scans, we calculate net rates of proliferation and invasion as well as radiation sensitivity for a patient's disease. Here, we present the application of our clinically targeted modelling approach to a single glioblastoma patient as a demonstration of our method. We apply our model in the full three-dimensional architecture of the brain to quantify the effects of regional resistance to radiation owing to hypoxia in vivo determined by [(18)F]-fluoromisonidazole positron emission tomography (FMISO-PET) and the patient-specific three-dimensional radiation treatment plan. Incorporation of hypoxia into our model with FMISO-PET increases the model-data agreement by an order of magnitude. This improvement was robust to our definition of hypoxia or the degree of radiation resistance quantified with the FMISO-PET image and our computational model, respectively. This work demonstrates a useful application of patient-specific modelling in personalized medicine and how mathematical modelling has the potential to unify multi-modality imaging and radiation treatment planning.

  20. Effects of Periodic Task-Specific Test Feedback on Physical Performance in Older Adults Undertaking Band-Based Resistance Exercise

    Directory of Open Access Journals (Sweden)

    Ryuichi Hasegawa

    2014-01-01

    Full Text Available The purpose of this study was to determine the effects of periodic task-specific test feedback on performance improvement in older adults undertaking community- and home-based resistance exercises (CHBRE. Fifty-two older adults (65–83 years were assigned to a muscular perfsormance feedback group (MPG, n=32 or a functional mobility feedback group (FMG, n=20. Both groups received exactly the same 9-week CHBRE program comprising one community-based and two home-based sessions per week. Muscle performance included arm curls and chair stands in 30 seconds, while functional mobility was determined by the timed up and go (TUG test. MPG received fortnightly test feedback only on muscle performance and FMG received feedback only on the TUG. Following training, there was a significant (P<0.05 interaction for all performance tests with MPG improving more for the arm curls (MPG 31.4%, FMG 15.9% and chair stands (MPG 33.7%, FMG 24.9% while FMG improved more for the TUG (MPG-3.5%, FMG-9.7%. Results from this nonrandomized study suggest that periodic test feedback during resistance training may enhance task-specific physical performance in older persons, thereby augmenting reserve capacity or potentially reducing the time required to recover functional abilities.

  1. Estimating the Contact Endurance of the AISI 321 Stainless Steel Under Contact Gigacycle Fatigue Tests

    Science.gov (United States)

    Savrai, R. A.; Makarov, A. V.; Osintseva, A. L.; Malygina, I. Yu.

    2018-02-01

    Mechanical testing of the AISI 321 corrosion resistant austenitic steel for contact gigacycle fatigue has been conducted with the application of a new method of contact fatigue testing with ultrasonic frequency of loading according to a pulsing impact "plane-to-plane" contact scheme. It has been found that the contact endurance (the ability to resist the fatigue spalling) of the AISI 321 steel under contact gigacycle fatigue loading is determined by its plasticity margin and the possibility of additional hardening under contact loading. It is demonstrated that the appearance of localized deep and long areas of spalling on a material surface can serve as a qualitative characteristic for the loss of the fatigue strength of the AISI 321 steel under impact contact fatigue loading. The value of surface microhardness measured within contact spots and the maximum depth of contact damages in the peripheral zone of contact spots can serve as quantitative criteria for that purpose.

  2. Improvements To Micro Contact Performance And Reliability

    Science.gov (United States)

    2016-12-22

    Fulfillment of the Requirements for the Degree of Doctor of Philosophy Tod V. Laurvick, B.S.E.E., M.S.E.E. Major, USAF 22 December 2016 DISTRIBUTION...complete customization of each device if desired. Another crucial fabrication characteristic of micro-contacts involves the thin- films used as a contact...surface. This work demonstrates that integration iv of thin- film spreading resistance theory into the most advanced contact resistance models to date

  3. The changing pattern of antimicrobial resistance within 42,033 Escherichia coli isolates from nosocomial, community and urology patient-specific urinary tract infections, Dublin, 1999-2009.

    LENUS (Irish Health Repository)

    Cullen, Ivor M

    2012-04-01

    To investigate the changing pattern of antimicrobial resistance in Escherichia coli urinary tract infection over an eleven year period, and to determine whether E. coli antibiotic resistance rates vary depending on whether the UTI represents a nosocomial, community acquired or urology patient specific infection.

  4. Transition metal contacts to graphene

    Energy Technology Data Exchange (ETDEWEB)

    Politou, Maria, E-mail: Maria.Politou@imec.be; De Gendt, Stefan; Heyns, Marc [KU Leuven, 3001 Leuven (Belgium); imec, Kapeldreef 75, 3001 Leuven (Belgium); Asselberghs, Inge; Radu, Iuliana; Conard, Thierry; Richard, Olivier; Martens, Koen; Huyghebaert, Cedric; Tokei, Zsolt [imec, Kapeldreef 75, 3001 Leuven (Belgium); Lee, Chang Seung [SAIT, Samsung Electronics Co., Suwon 443-803 (Korea, Republic of); Sayan, Safak [imec, Kapeldreef 75, 3001 Leuven (Belgium); Intel Corporation, 2200 Mission College Blvd, Santa Clara, California 95054 (United States)

    2015-10-12

    Achieving low resistance contacts to graphene is a common concern for graphene device performance and hybrid graphene/metal interconnects. In this work, we have used the circular Transfer Length Method (cTLM) to electrically characterize Ag, Au, Ni, Ti, and Pd as contact metals to graphene. The consistency of the obtained results was verified with the characterization of up to 72 cTLM structures per metal. Within our study, the noble metals Au, Ag and Pd, which form a weaker bond with graphene, are shown to result in lower contact resistance (Rc) values compared to the more reactive Ni and Ti. X-ray Photo Electron Spectroscopy and Transmission Electron Microscopy characterization for the latter have shown the formation of Ti and Ni carbides. Graphene/Pd contacts show a distinct intermediate behavior. The weak carbide formation signature and the low Rc values measured agree with theoretical predictions of an intermediate state of weak chemisorption of Pd on graphene.

  5. Prioritized Contact Transport Stream

    Science.gov (United States)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  6. Time-of-day specific changes in metabolic detoxification and insecticide resistance in the malaria mosquito Anopheles gambiae.

    Science.gov (United States)

    Balmert, Nathaniel J; Rund, Samuel S C; Ghazi, John P; Zhou, Peng; Duffield, Giles E

    2014-05-01

    Mosquitoes exhibit ∼24 h rhythms in physiology and behavior, regulated by the cooperative action of an endogenous circadian clock and the environmental light:dark cycle. Here, we characterize diel (observed under light:dark conditions) time-of-day changes in metabolic detoxification and resistance to insecticide challenge in Anopheles gambiae mosquitoes. A better understanding of mosquito chronobiology will yield insights into developing novel control strategies for this important disease vector. We have previously identified >2000 rhythmically expressed An. gambiae genes. These include metabolic detoxification enzymes peaking at various times throughout the day. Especially interesting was the identification of rhythmic genes encoding enzymes capable of pyrethroid and/or DDT metabolism (CYP6M2, CYP6P3, CYP6Z1, and GSTE2). We hypothesized that these temporal changes in gene expression would confer time-of-day specific changes in metabolic detoxification and responses to insecticide challenge. An. gambiae mosquitoes (adult female Pimperena and Mali-NIH strains) were tested by gene expression analysis for diel rhythms in key genes associated with insecticidal resistance. Biochemical assays for total GST, esterase, and oxidase enzymatic activities were undertaken on time-specific mosquito head and body protein lysates. To determine for rhythmic susceptibility to insecticides by survivorship, mosquitoes were exposed to DDT or deltamethrin across the diel cycle. We report the occurrence of temporal changes in GST activity in samples extracted from the body and head with a single peak at late-night to dawn, but no rhythms were detected in oxidase or esterase activity. The Pimperena strain was found to be resistant to insecticidal challenge, and subsequent genomic analysis revealed the presence of the resistance-conferring kdr mutation. We observed diel rhythmicity in key insecticide detoxification genes in the Mali-NIH strain, with peak phases as previously reported in

  7. Contact Lens Related Corneal Ulcer

    OpenAIRE

    Loh, KY; Agarwal, P

    2010-01-01

    A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are: overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. Th...

  8. Carrier Transport of Silver Nanowire Contact to p-GaN and its Influence on Leakage Current of LEDs

    Science.gov (United States)

    Oh, Munsik; Kang, Jae-Wook; Kim, Hyunsoo

    2018-03-01

    The authors investigated the silver nanowires (AgNWs) contact formed on p-GaN. Transmission line model applied to the AgNWs contact to p-GaN produced near ohmic contact with a specific contact resistance (ρ sc) of 10-1˜10-4 Ω·cm2. Noticeably, the contact resistance had a strong bias-voltage (or current-density) dependence associated with a local joule heating effect. Current-voltage-temperature (I-V-T) measurement revealed a strong temperature dependence with respect to ρ sc, indicating that the temperature played a key role of an enhanced carrier transport. The local joule heating at AgNW/GaN interface, however, resulted in a generation of leakage current of light-emitting diodes (LEDs) caused by degradation of AgNW contact.

  9. Time-wise change in neck pain in response to rehabilitation with specific resistance training: implications for exercise prescription.

    Directory of Open Access Journals (Sweden)

    Mette K Zebis

    Full Text Available PURPOSE: To determine the time-wise effect of specific resistance training on neck pain among industrial technicians with frequent neck pain symptoms. METHODS: Secondary analysis of a parallel-group cluster randomized controlled trial of 20 weeks performed at two large industrial production units in Copenhagen, Denmark. Women with neck pain >30 mm VAS (N = 131 were included in the present analysis. The training group (N = 77 performed specific resistance training for the neck/shoulder muscles three times a week, and the control group (N = 54 received advice to stay active. Participants of both groups registered neck pain intensity (0-100 mm VAS once a week. RESULTS: Neck pain intensity was 55 mm (SD 23 at baseline. There was a significant group by time interaction for neck pain (F-value 2.61, P<0.001, DF = 19. Between-group differences in neck pain reached significance after 4 weeks (11 mm, 95% CI 2 to 20. The time-wise change in pain showed three phases; a rapid decrease in the training group compared with the control group during the initial 7 weeks, a slower decrease in pain during the following weeks (week 8-15, and a plateau during the last weeks (week 16-20. Adherence to training followed a two-phase pattern, i.e. weekly participation rate was between 70-86% during the initial 7 weeks, dropping towards 55-63% during the latter half of the training period. CONCLUSION: Four weeks of specific resistance training reduced neck pain significantly, but 15 weeks is required to achieve maximal pain reduction. The time-wise change in pain followed a three-phase pattern with a rapid effect during the initial 7 weeks followed by a slower but still positive effect, and finally a plateau from week 15 and onwards. Decreased participation rate may explain the decreased efficacy during the latter phase of the intervention.

  10. The dual-specificity phosphatase 2 (DUSP2 does not regulate obesity-associated inflammation or insulin resistance in mice.

    Directory of Open Access Journals (Sweden)

    Graeme I Lancaster

    Full Text Available Alterations in the immune cell profile and the induction of inflammation within adipose tissue are a hallmark of obesity in mice and humans. Dual-specificity phosphatase 2 (DUSP2 is widely expressed within the immune system and plays a key role promoting immune and inflammatory responses dependent on mitogen-activated protein kinase (MAPK activity. We hypothesised that the absence of DUSP2 would protect mice against obesity-associated inflammation and insulin resistance. Accordingly, male and female littermate mice that are either wild-type (wt or homozygous for a germ-line null mutation of the dusp2 gene (dusp2-/- were fed either a standard chow diet (SCD or high fat diet (HFD for 12 weeks prior to metabolic phenotyping. Compared with mice fed the SCD, all mice consuming the HFD became obese, developed glucose intolerance and insulin resistance, and displayed increased macrophage recruitment and markers of inflammation in epididymal white adipose tissue. The absence of DUSP2, however, had no effect on the development of obesity or adipose tissue inflammation. Whole body insulin sensitivity in male mice was unaffected by an absence of DUSP2 in response to either the SCD or HFD; however, HFD-induced insulin resistance was slightly, but significantly, reduced in female dusp2-/- mice. In conclusion, DUSP2 plays no role in regulating obesity-associated inflammation and only a minor role in controlling insulin sensitivity following HFD in female, but not male, mice. These data indicate that rather than DUSP2 being a pan regulator of MAPK dependent immune cell mediated inflammation, it appears to differentially regulate inflammatory responses that have a MAPK component.

  11. Differential microRNA expression signatures and cell type-specific association with Taxol resistance in ovarian cancer cells

    Directory of Open Access Journals (Sweden)

    Kim YW

    2014-02-01

    downregulation of the two miRNAs was associated with better survival, perhaps increasing the sensitivity of cancer cells to Taxol. In the chemo-sensitive patient group, only miR-647 could be a prognosis marker. These miRNAs inhibit several interacting genes of p53 networks, especially in TUOS-3 and TUOS-4, and showed cell line-specific inhibition effects. Taken together, the data indicate that the three miRNAs are closely associated with Taxol resistance and potentially better prognosis factors. Our results suggest that these miRNAs were successfully and reliably identified and would be used in the development of miRNA therapies in treating ovarian cancer. Keywords: microRNA, ovarian cancer, Taxol resistance, Kaplan–Meier survival analysis

  12. Simulation for fretting corrosion of tin-coated copper contacts

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.Y.; Joo, H.G. [Stress Analysis and Failure Design Laboratory, School of Mechanical Engineering, Yonsei University, 134, Sinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Jeong, D.K. [Research and Development Division, Hyundai-Kia Motors 772-1, Jangduk-dong, Hwaseong Gyeonggi 445-706 (Korea, Republic of); Park, Y.W. [Technical Research Laboratories, POSCO, P.O.Box 36, Goedong-dong, Nam-gu, Pohang Gyeongbuk 790-300 (Korea, Republic of)

    2011-04-15

    The simulations of contact resistance variation under various oxide fractions are conducted. The copper oxide is assigned on the contact area with various fractions by the random distribution technique. The calculated contact resistance at each oxide area fraction is compared with the experimental result. The increase in contact resistance results in an increased oxide area fraction. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Improved Contacts to MoS2 Transistors by Ultra-High Vacuum Metal Deposition.

    Science.gov (United States)

    English, Chris D; Shine, Gautam; Dorgan, Vincent E; Saraswat, Krishna C; Pop, Eric

    2016-06-08

    The scaling of transistors to sub-10 nm dimensions is strongly limited by their contact resistance (RC). Here we present a systematic study of scaling MoS2 devices and contacts with varying electrode metals and controlled deposition conditions, over a wide range of temperatures (80 to 500 K), carrier densities (10(12) to 10(13) cm(-2)), and contact dimensions (20 to 500 nm). We uncover that Au deposited in ultra-high vacuum (∼10(-9) Torr) yields three times lower RC than under normal conditions, reaching 740 Ω·μm and specific contact resistivity 3 × 10(-7) Ω·cm(2), stable for over four months. Modeling reveals separate RC contributions from the Schottky barrier and the series access resistance, providing key insights on how to further improve scaling of MoS2 contacts and transistor dimensions. The contact transfer length is ∼35 nm at 300 K, which is verified experimentally using devices with 20 nm contacts and 70 nm contact pitch (CP), equivalent to the "14 nm" technology node.

  14. A new method of making ohmic contacts to p-GaN

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Gutierrez, C.A., E-mail: chernandez@fis.cinvestav.mx [DNyN, Cinvestav-IPN, México, DF, 07360 (Mexico); Kudriavtsev, Yu. [Departamento Ingeniería Eléctrica – SEES, Cinvestav-IPN, México, DF, 07360 (Mexico); Mota, Esteban [ESIME, Instituto Politécnico Nacional, México, DF, 07738 (Mexico); Hernández, A.G.; Escobosa-Echavarría, A.; Sánchez-Resendiz, V. [Departamento Ingeniería Eléctrica – SEES, Cinvestav-IPN, México, DF, 07360 (Mexico); Casallas-Moreno, Y.L.; López-López, M. [Departamento Física, Cinvestav-IPN, México, DF, 07360 (Mexico)

    2016-12-01

    Highlights: • Low resistance Ohmic contacts preparation is based on low energy high dose In{sup +} ion implantation into Metal/p-GaN to achieve a thin layer of In{sub x}Ga{sub 1-x}N just at the interface. • The specific ohmic contact was reduced from 10{sup −2} Ωcm{sup 2} to 2.5 × 10{sup −4} Ωcm{sup 2}. - Abstract: The structural, chemical, and electrical characteristics of In{sup +} ion-implanted Au/Ni, Au/Nb and Au/W ohmic contacts to p-GaN were investigated. After the preparation of Ni, Nb and W electrode on the surface of p-GaN, the metal/p-GaN contact interface was implanted by 30 keV In{sup +} ions with an implantation dose of 5 × 10{sup 15} ions/cm{sup 2} at room temperature to form a thin layer of In{sub x}Ga{sub 1-x}N located at the metal-semiconductor interface, achieved to reduce the specific contact resistance due to the improving quantum tunneling transport trough to the structure. The characterization was carried out by high-resolution X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and secondary ion mass spectrometry to investigate the formation of ternary alloy, re-crystallization by rapid thermal annealing process after In{sup +} implantation, and the redistribution of elements. The specific contact resistance was extracted by current-voltage (I-V) curves using transmission line method; the lowest specific contact resistance of 2.5 × 10{sup −4} Ωcm{sup 2} was achieved for Au/Ni/p-In{sub x}Ga{sub 1-x}N/p-GaN ohmic contacts.

  15. Branched-chain and aromatic amino acids, insulin resistance and liver specific ectopic fat storage in overweight to obese subjects.

    Science.gov (United States)

    Haufe, S; Witt, H; Engeli, S; Kaminski, J; Utz, W; Fuhrmann, J C; Rein, D; Schulz-Menger, J; Luft, F C; Boschmann, M; Jordan, J

    2016-07-01

    Amino acids may interfere with insulin action, particularly in obese individuals. We hypothesized that increased circulating branched-chain and aromatic amino acids herald insulin resistance and ectopic fat storage, particularly hepatic fat accumulation. We measured fasting branched-chain and aromatic amino acids (tryptophan, tyrosine, and phenylalanine) by mass spectrometry in 111 overweight to obese subjects. We applied abdominal magnetic resonance imaging and spectroscopy to assess adipose tissue distribution and ectopic fat storage, respectively. Plasma branched-chain amino acids concentrations were related to insulin sensitivity and intrahepatic fat independent from adiposity, age and gender, but not to abdominal adipose tissue or intramyocellular fat. In weight stable overweight and obese individuals, branched-chain amino acid concentrations are specifically associated with hepatic fat storage and insulin resistance. Copyright © 2016 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.

  16. Strain-Specific V3 and CD4 Binding Site Autologous HIV-1 Neutralizing Antibodies Select Neutralization-Resistant Viruses.

    Science.gov (United States)

    Moody, M Anthony; Gao, Feng; Gurley, Thaddeus C; Amos, Joshua D; Kumar, Amit; Hora, Bhavna; Marshall, Dawn J; Whitesides, John F; Xia, Shi-Mao; Parks, Robert; Lloyd, Krissey E; Hwang, Kwan-Ki; Lu, Xiaozhi; Bonsignori, Mattia; Finzi, Andrés; Vandergrift, Nathan A; Alam, S Munir; Ferrari, Guido; Shen, Xiaoying; Tomaras, Georgia D; Kamanga, Gift; Cohen, Myron S; Sam, Noel E; Kapiga, Saidi; Gray, Elin S; Tumba, Nancy L; Morris, Lynn; Zolla-Pazner, Susan; Gorny, Miroslaw K; Mascola, John R; Hahn, Beatrice H; Shaw, George M; Sodroski, Joseph G; Liao, Hua-Xin; Montefiori, David C; Hraber, Peter T; Korber, Bette T; Haynes, Barton F

    2015-09-09

    The third variable (V3) loop and the CD4 binding site (CD4bs) of the HIV-1 envelope are frequently targeted by neutralizing antibodies (nAbs) in infected individuals. In chronic infection, HIV-1 escape mutants repopulate the plasma, and V3 and CD4bs nAbs emerge that can neutralize heterologous tier 1 easy-to-neutralize but not tier 2 difficult-to-neutralize HIV-1 isolates. However, neutralization sensitivity of autologous plasma viruses to this type of nAb response has not been studied. We describe the development and evolution in vivo of antibodies distinguished by their target specificity for V3 and CD4bs epitopes on autologous tier 2 viruses but not on heterologous tier 2 viruses. A surprisingly high fraction of autologous circulating viruses was sensitive to these antibodies. These findings demonstrate a role for V3 and CD4bs antibodies in constraining the native envelope trimer in vivo to a neutralization-resistant phenotype, explaining why HIV-1 transmission generally occurs by tier 2 neutralization-resistant viruses. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Transgenic expression in citrus of single-chain antibody fragments specific to Citrus tristeza virus confers virus resistance.

    Science.gov (United States)

    Cervera, Magdalena; Esteban, Olga; Gil, Maite; Gorris, M Teresa; Martínez, M Carmen; Peña, Leandro; Cambra, Mariano

    2010-12-01

    Citrus tristeza virus (CTV) causes one of the most destructive viral diseases of citrus worldwide. Generation of resistant citrus genotypes through genetic engineering could be a good alternative to control CTV. To study whether production of single-chain variable fragment (scFv) antibodies in citrus could interfere and immunomodulate CTV infection, transgenic Mexican lime plants expressing two different scFv constructs, separately and simultaneously, were generated. These constructs derived from the well-referenced monoclonal antibodies 3DF1 and 3CA5, specific against CTV p25 major coat protein, whose mixture is able to detect all CTV isolates characterized so far. ScFv accumulation levels were low and could be readily detected just in four transgenic lines. Twelve homogeneous and vigorous lines were propagated and CTV-challenged by graft inoculation with an aggressive CTV strain. A clear protective effect was observed in most transgenic lines, which showed resistance in up to 40-60% of propagations. Besides, both a delay in symptom appearance and attenuation of symptom intensity were observed in infected transgenic plants compared with control plants. This effect was more evident in lines carrying the 3DF1scFv transgene, being probably related to the biological functions of the epitope recognized by this antibody. This is the first report describing successful protection against a pathogen in woody transgenic plants by ectopic expression of scFv recombinant antibodies.

  18. Ultraviolet action spectra for aerobic and anaerobic inactivation of Escherichia coli strains specifically sensitive and resistant to near ultraviolet radiations

    International Nuclear Information System (INIS)

    Peak, J.G.; Peak, M.J.; Tuveson, R.W.

    1983-01-01

    Action spectra for the lethal effects of ultraviolet light (254-434 nm) irradiation delivered under aerobic or anaerobic conditions to Escherichia coli RT2 (specifically sensitive to near-UV radiation; > 320 nm) and E. coli RT4 (near-UV resistant) were prepared. Negligible oxygen dependence was observed for both strains below about 315 nm. The oxygen enhancement ratio (OER) for RT4 increased above this wavelength to the longest wavelength used, whereas for RT2 there was a greater increase in the OER to a large peak at 365 nm, then a progressive decrease at longer wavelengths. The results are consistent with the possibility that the sensitivity of strain RT2 to near-UV radiation may be due to hyperproduction of photosensitizer, operating via photodynamic type reactions involving excited species of oxygen. (author)

  19. Site specific isolated nanostructure array formation on a large area by broad ion beam without any mask and resist

    Science.gov (United States)

    Karmakar, Prasanta; Satpati, Biswarup

    2014-06-01

    We report the formation of isolated nanostructure arrays on a large area via broad ion beam implantation without the aid of any mask or resist. Desired ions have been implanted at specific locations of the prefabricated silicon ripple or triangular structures by exploiting the variation of local ion impact angles. We have shown that the implantation of Fe ions on an O+ ions induced pre fabricated triangular shaped patterned Si surface results in a self-organized periodic array of striped magnetic nanostructures having several micron length and about 50 nm width arranged with a spacial separation of ˜200 nm. The morphology, composition, crystalline structure, and magnetic property of these nanopatterns have been analyzed using high-resolution cross-sectional transmission electron microscopy and atomic force microscopy. A geometrical model has been proposed to explain the fundamental features of such ion-induced nanopattern structures.

  20. Substrate specificity of the OqxAB multidrug resistance pump in Escherichia coli and selected enteric bacteria

    DEFF Research Database (Denmark)

    Hansen, Lars Hestbjerg; Jensen, Lars Bogø; Sørensen, Heidi Iskou

    2007-01-01

    Objectives: A plasmid-encoded multidrug eff lux pump, OqxAB, identified in Escherichia coli of porcine origin, was tested for substrate specificity against selected antibiotics, detergents and disinfectants. The ability of horizontal transfer to food-borne pathogens of the Enterobacteriaceae family......, Klebsiella pneumoniae, Kluyvera sp. and Enterobacter aerogrenes was investigated. The effect of the presence of the OqxAB pump on susceptibility for selected compounds was investigated using broth dilution assays. Results: The OqxAB pump conferred antimicrobial resistance or reduced susceptibility towards...... a variety of substrates in E. coli. These included animal growth promoters, antimicrobials, disinfectants and detergents. pOLA52 could readily be transferred to enterobacterial pathogens. Transconjugants showed reduced susceptibility towards chloramphenicol, ciprofloxacin and olaquindox. Conclusions...

  1. A 2-Month Linear Periodized Resistance Exercise Training Improved Musculoskeletal Fitness and Specific Conditioning of Navy Cadets.

    Science.gov (United States)

    Vantarakis, Antonios; Chatzinikolaou, Athanasios; Avloniti, Alexandra; Vezos, Nikolaos; Douroudos, Ioannis I; Draganidis, Dimitrios; Jamurtas, Athanasios Z; Kambas, Antonis; Kalligeros, Stamatios; Fatouros, Ioannis G

    2017-05-01

    Vantarakis, A, Chatzinikolaou, A, Avloniti, A, Vezos, N, Douroudos, II, Draganidis, D, Jamurtas, AΖ, Kambas, A, Kalligeros, S, and Fatouros, IG. A 2-month linear periodized resistance exercise training improved musculoskeletal fitness and specific conditioning of navy cadets. J Strength Cond Res 31(5): 1362-1370, 2017-Major objectives of army and navy training are the development of readiness, performance, and injury prevention. Numerous studies have examined the effect of specific strength training (ST) programs on performance of Special Forces and military personnel. Although navy personnel have to address on-board conditions that require the development of strength, agility, speed, and task-specific endurance, there is no information regarding the effects of ST on navy-specific performance. Therefore, the purpose of this study was to investigate the effect of an 8-week ST on performance of navy cadets. Thirty-one cadets of the Hellenic Naval Academy volunteered to participate and were randomly assigned in 2 groups. Cadets in the Experimental Group participated in a linear periodized ST program in addition to their daily training schedule. Cadets in the control group participated only in pre- and post-measurements. Anthropometrics, maximal oxygen consumption, oxygen consumption during a Navy Obstacle Course (NOC), maximum strength in bench press and squat exercises, hand grip strength, repetitions in push-ups and abdominal test, time to complete a 30-m sprint, and time to complete NOC were measured before and after the intervention. A 2-way repeated-measures analysis of variance showed that ST induced favorable changes in bench press and squat 1 repetition maximum, push-ups, abdominal crunches, time to complete 30-m distance, and time to complete the NOC. These results indicate that an additional ST may induce positive alterations on readiness and performance of navy cadets. The study has the approval of university's institutional review board and ethical

  2. Th1 lymphokine production profiles of nickel-specific CD4+T-lymphocyte clones from nickel contact allergic and non-allergic individuals

    NARCIS (Netherlands)

    Kapsenberg, M. L.; Wierenga, E. A.; Stiekema, F. E.; Tiggelman, A. M.; Bos, J. D.

    1992-01-01

    Panels of nickel-specific T-lymphocyte clones (TLC) were prepared from nickel-allergic and non-allergic donors. TLC from both panels showed similar levels of expression of TCR alpha/beta, CD4, CD2, CD25, and CD29 and recognized nickel in association with class II HLA molecules with restriction

  3. Prevalence and characteristics of methicillin-resistant coagulase-negative staphylococci from livestock, chicken carcasses, bulk tank milk, minced meat, and contact persons

    Directory of Open Access Journals (Sweden)

    Zweifel Claudio

    2011-01-01

    Full Text Available Abstract Background Methicillin-resistant coagulase-negative staphylococci (MR-CNS are of increasing importance to animal and public health. In veterinary medicine and along the meat and milk production line, only limited data were so far available on MR-CNS characteristics. The aim of the present study was to evaluate the prevalence of MR-CNS, to identify the detected staphylococci to species level, and to assess the antibiotic resistance profiles of isolated MR-CNS strains. Results After two-step enrichment and growth on chromogenic agar, MR-CNS were detected in 48.2% of samples from livestock and chicken carcasses, 46.4% of samples from bulk tank milk and minced meat, and 49.3% of human samples. Using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS, 414 selected MR-CNS strains belonged to seven different species (S. sciuri, 32.6%; S. fleurettii, 25.1%; S. haemolyticus, 17.4%; S. epidermidis, 14.5%, S. lentus, 9.2%; S. warneri, 0.7%; S. cohnii, 0.5%. S. sciuri and S. fleurettii thereby predominated in livestock, BTM and minced meat samples, whereas S. epidermidis and S. haemolyticus predominated in human samples. In addition to beta-lactam resistance, 33-49% of all 414 strains were resistant to certain non-beta-lactam antibiotics (ciproflaxacin, clindamycin, erythromycin, tetracycline. Conclusions A high prevalence of MR-CNS was found in livestock production. This is of concern in view of potential spread of mecA to S. aureus (MRSA. Multiresistant CNS strains might become an emerging problem for veterinary medicine. For species identification of MR-CNS isolated from different origins, MALDI-TOF MS proved to be a fast and reliable tool and is suitable for screening of large sample amounts.

  4. Propolis and Herba Epimedii extracts enhance the non-specific immune response and disease resistance of Chinese sucker, Myxocyprinus asiaticus.

    Science.gov (United States)

    Zhang, Guobin; Gong, Shiyuan; Yu, Denghang; Yuan, Hanwen

    2009-03-01

    The effect of traditional Chinese medicine (TCM) formulated from propolis and Herba Epimedii extracts at the ratio of 3:1 (w/w) on non-specific immune response of Chinese sucker (Myxocyprinus asiaticus) was investigated. Fish were fed diets containing 0 (control), 0.1%, 0.5% or 1.0% TCM extracts for five weeks. The respiratory burst and phagocytic activities of blood leukocytes, lysozyme and natural haemolytic complement activities in plasma were measured weekly. After five weeks of feeding, fish were infected with Aeromonas hydrophila and mortalities were recorded. Results of this study showed that feeding Chinese sucker with different dosage of TCM extracts stimulated respiratory burst activity, phagocytosis of phagocytic cells in blood and lysozyme activity in plasma. They had no effect on plasma natural haemolytic complement activity. All dosage of treated groups showed reduced mortality following A. hydrophila infection. Feed containing 0.5% TCM extracts was the most effective with the mortality of the fish significantly reduced by 35% compared to the control. The results indicate that propolis and Herba Epimedii extracts in combination enhances the non-specific immune response and disease resistance of Chinese sucker against A. hydrophila.

  5. [Computers and contact dermatitis].

    Science.gov (United States)

    Dooms-Goossens, A

    1989-01-01

    A computerized database with the complete composition of pharmaceutical products and some cosmetics helps the patient with an allergic contact dermatitis reaction to avoid his specific allergens. Together with a database with patient information (12000 cases) this product, file serves as the basis for an expert system that assists the dermatologist during his every day clinical practice. The use of the computer in the field of contact dermatitis has gained much interest in the course of the last decade. In fact, the computer can be a particularly helpful tool in: 1. The storage of large amounts of data that can help to identify the patient's allergen microenvironment: --literature: articles related to contact dermatitis problems; --product information such as, for example, the composition of pharmaceutical, cosmetics, and industrial materials; --the dermatologist: the filling in of a standardized anamnesis from also helps to assure that relevant clinical data is not overlooked. 2. The diagnosis of allergic contact dermatitis: on the basis of all these data stored, an expert system can be developed to provide targeted information to assist the physician with the anamnesis of a new patient. Depending on the profile of the patient, several factors that could be at the source of the contact dermatitis, such as the patient's profession, hobbies, and use of pharmaceutical products and cosmetics, can be considered, thus increasing the efficiency of the allergological examination considerably. 3. Research in contact dermatitis: --The data can be used for epidemiological analyses in behalf of the patients, the medical profession, the industry, and the authorities.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. EDITORIAL: Close contact Close contact

    Science.gov (United States)

    Demming, Anna

    2010-07-01

    The development of scanning probe techniques, such as scanning tunnelling microscopy [1], has often been touted as the catalyst for the surge in activity and progress in nanoscale science and technology. Images of nanoscale structural detail have served as an invaluable investigative resource and continue to fascinate with the fantastical reality of an intricate nether world existing all around us, but hidden from view of the naked eye by a disparity in scale. As is so often the case, the invention of the scanning tunnelling microscope heralded far more than just a useful new apparatus, it demonstrated the scope for exploiting the subtleties of electronic contact. The shrinking of electronic devices has been a driving force for research into molecular electronics, in which an understanding of the nature of electronic contact at junctions is crucial. In response, the number of experimental techniques in molecular electronics has increased rapidly in recent years. Scanning tunnelling microscopes have been used to study electron transfer through molecular films on a conducting substrate, and the need to monitor the contact force of scanning tunnelling electrodes led to the use of atomic force microscopy probes coated in a conducting layer as studied by Cui and colleagues in Arizona [2]. In this issue a collaboration of researchers at Delft University and Leiden University in the Netherlands report a new device architecture for the independent mechanical and electrostatic tuning of nanoscale charge transport, which will enable thorough studies of molecular transport in the future [3]. Scanning probes can also be used to pattern surfaces, such as through spatially-localized Suzuki and Heck reactions in chemical scanning probe lithography. Mechanistic aspects of spatially confined Suzuki and Heck chemistry are also reported in this issue by researchers in Oxford [4]. All these developments in molecular electronics fabrication and characterization provide alternative

  7. Ward-Specific Rates of Nasal Cocolonization with Methicillin-Susceptible and -Resistant Staphylococcus spp. and Potential Impact on Molecular Methicillin-Resistant Staphylococcus aureus Screening Tests

    Science.gov (United States)

    Rasigade, Jean-Philippe; Lustig, Sebastien; Lhoste, Yannick; Valour, Florent; Guerin, Claude; Aubrun, Frederic; Tigaud, Sylvestre; Laurent, Frederic

    2013-01-01

    We report that the rates of nasal cocolonization with methicillin-susceptible Staphylococcus aureus and methicillin-resistant coagulase-negative staphylococci can vary widely between patients admitted to different wards within a single hospital. Such cocolonization can greatly influence the performance of molecular methicillin-resistant S. aureus (MRSA) screening tests depending on the methods used and targets selected. PMID:23658254

  8. The effect of the electron irradiation on the series resistance of Au/Ni/6H-SiC and Au/Ni/4H-SiC Schottky contacts

    International Nuclear Information System (INIS)

    Cinar, Kuebra; Coskun, C.; Aydogan, S.; Asil, Hatice; Guer, Emre

    2010-01-01

    The effect of electron irradiation on Au/Ni/6H-SiC and Au/Ni/4H-SiC Schottky contacts has been studied by current voltage (I-V) characterization at room temperature. The diodes have been subjected to the electron irradiation at various energies (6, 12 and 15 MeV) and influence of the electron irradiation on the diode parameters such as barrier height, ideality factor, and series resistance has been studied. Cheung functions, Norde model and conductance method have been used to determine the diode parameters. The ideality factor of the diodes is greater than unity indicating activation of some other current transport mechanism(s). The series resistances of the diodes increase by increasing electron energy. The reverse current increases for the Au/Ni/6H-SiC diode after each electron irradiation experiment, while decreasing trend is observed for Au/Ni/4H-SiC diode. Decrease in the barrier height of Au/Ni/4H-SiC diode is observed and mainly attributed to the increase of the reverse current, while the decrease of the forward current is caused by increase in series resistance, for high electron irradiation energies.

  9. The effect of the electron irradiation on the series resistance of Au/Ni/6H-SiC and Au/Ni/4H-SiC Schottky contacts

    Energy Technology Data Exchange (ETDEWEB)

    Cinar, Kuebra [Department of Physics, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey); Coskun, C., E-mail: ccoskun@atauni.edu.t [Department of Physics, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey); Aydogan, S.; Asil, Hatice; Guer, Emre [Department of Physics, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey)

    2010-03-15

    The effect of electron irradiation on Au/Ni/6H-SiC and Au/Ni/4H-SiC Schottky contacts has been studied by current voltage (I-V) characterization at room temperature. The diodes have been subjected to the electron irradiation at various energies (6, 12 and 15 MeV) and influence of the electron irradiation on the diode parameters such as barrier height, ideality factor, and series resistance has been studied. Cheung functions, Norde model and conductance method have been used to determine the diode parameters. The ideality factor of the diodes is greater than unity indicating activation of some other current transport mechanism(s). The series resistances of the diodes increase by increasing electron energy. The reverse current increases for the Au/Ni/6H-SiC diode after each electron irradiation experiment, while decreasing trend is observed for Au/Ni/4H-SiC diode. Decrease in the barrier height of Au/Ni/4H-SiC diode is observed and mainly attributed to the increase of the reverse current, while the decrease of the forward current is caused by increase in series resistance, for high electron irradiation energies.

  10. Mycobacterium tuberculosis Whole Genome Sequences From Southern India Suggest Novel Resistance Mechanisms and the Need for Region-Specific Diagnostics.

    Science.gov (United States)

    Manson, Abigail L; Abeel, Thomas; Galagan, James E; Sundaramurthi, Jagadish Chandrabose; Salazar, Alex; Gehrmann, Thies; Shanmugam, Siva Kumar; Palaniyandi, Kannan; Narayanan, Sujatha; Swaminathan, Soumya; Earl, Ashlee M

    2017-06-01

    India is home to 25% of all tuberculosis cases and the second highest number of multidrug resistant cases worldwide. However, little is known about the genetic diversity and resistance determinants of Indian Mycobacterium tuberculosis, particularly for the primary lineages found in India, lineages 1 and 3. We whole genome sequenced 223 randomly selected M. tuberculosis strains from 196 patients within the Tiruvallur and Madurai districts of Tamil Nadu in Southern India. Using comparative genomics, we examined genetic diversity, transmission patterns, and evolution of resistance. Genomic analyses revealed (11) prevalence of strains from lineages 1 and 3, (11) recent transmission of strains among patients from the same treatment centers, (11) emergence of drug resistance within patients over time, (11) resistance gained in an order typical of strains from different lineages and geographies, (11) underperformance of known resistance-conferring mutations to explain phenotypic resistance in Indian strains relative to studies focused on other geographies, and (11) the possibility that resistance arose through mutations not previously implicated in resistance, or through infections with multiple strains that confound genotype-based prediction of resistance. In addition to substantially expanding the genomic perspectives of lineages 1 and 3, sequencing and analysis of M. tuberculosis whole genomes from Southern India highlight challenges of infection control and rapid diagnosis of resistant tuberculosis using current technologies. Further studies are needed to fully explore the complement of diversity and resistance determinants within endemic M. tuberculosis populations.

  11. Specificity of machine, barbell, and water-filled log bench press resistance training on measures of strength.

    Science.gov (United States)

    Langford, George A; McCurdy, Kevin W; Ernest, James M; Doscher, Michael W; Walters, Stacey D

    2007-11-01

    The purpose of this study was to compare the effects of 10 weeks of resistance training with an isotonic bench press machine and 2 types of free-weight bench press exercises on several measures bench press strength. Specificity was investigated by comparing the ability to transfer strength gained from a type of training that differed from the mode of testing. Forty-nine men participated in the study. The subjects completed a pretest on the machine (MB), barbell (BB), isokinetic (IB), and log (LB) bench press to determine baseline strength and completed 10 weeks of training on the MB, BB, or LB. The 3 groups were tested to see whether differential training effects occurred from pre- to posttest scores on the BB, MB, LB, and peak force on the IB. By multivariate analysis, the trial-by-group interaction was not statistically significant. The multivariate and subsequent univariate analyses of variance tests indicated statistically significant effects from pre- to posttest for peak force on the IB test and the BB, MB, and LB. Correlations among the strength tests were high (0.92 > or = r or = r < pr = 0.83). Mean 3 repetition maximum MB strength was 8% higher than BB strength, which was 3% higher than LB strength, indicating differences in the amount of stabilization required to control the resistance. The findings of this study showed that all 3 training groups significantly improved in strength during short-term training on the MB, BB, and LB. These data lend evidence that improved strength after training on the MB, BB, and LB equally transfers to strength gains on any of the 4 modes of testing. These results should be considered when including similar exercises varying in stability into the training program to improve strength.

  12. Microstructure of V-based ohmic contacts to AlGaN/GaN heterostructures at a reduced annealing temperature

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, A., E-mail: alexander.schmid@physik.tu-freiberg.de; Schroeter, Ch.; Otto, R.; Heitmann, J. [Institute of Applied Physics, TU Bergakademie Freiberg, 09599 Freiberg (Germany); Schuster, M. [Namlab gGmbH, 01187 Dresden (Germany); Klemm, V.; Rafaja, D. [Institute of Materials Science, TU Bergakademie Freiberg, 09599 Freiberg (Germany)

    2015-02-02

    Ohmic contacts with V/Al/Ni/Au and V/Ni/Au metalization schemes were deposited on AlGaN/GaN heterostructures. The dependence of the specific contact resistance on the annealing conditions and the V:Al thickness ratio was shown. For an optimized electrode stack, a low specific contact resistance of 8.9 × 10{sup −6} Ω cm{sup 2} was achieved at an annealing temperature of 650 °C. Compared to the conventional Ti/Al/Ni/Au contact, this is a reduction of 150 K. The microstructure and contact formation at the AlGaN/metal interface were investigated by transmission electron microscopy including high-resolution micrographs and energy dispersive X-ray analysis. It was shown that for low-resistive contacts, the resistivity of the metalization has to be taken into account. The V:Al thickness ratio has an impact on the formation of different intermetallic phases and thus is crucial for establishing ohmic contacts at reduced annealing temperatures.

  13. Specification for corrosion-resisting chromium and chromium-nickel steel bare and composite metal cored and stranded arc welding electrodes and welding rods

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    This specification prescribes requirements for corrosion or heat resisting chromium and chromium-nickel steel electrodes and welding rods. These electrodes and welding rods are normally used for arc welding and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

  14. The Biofilm-Specific Antibiotic Resistance Gene ndvB Is Important for Expression of Ethanol Oxidation Genes in Pseudomonas aeruginosa Biofilms

    OpenAIRE

    Beaudoin, Trevor; Zhang, Li; Hinz, Aaron J.; Parr, Christopher J.; Mah, Thien-Fah

    2012-01-01

    Bacteria growing in biofilms are responsible for a large number of persistent infections and are often more resistant to antibiotics than are free-floating bacteria. In a previous study, we identified a Pseudomonas aeruginosa gene, ndvB, which is important for the formation of periplasmic glucans. We established that these glucans function in biofilm-specific antibiotic resistance by sequestering antibiotic molecules away from their cellular targets. In this study, we investigate another func...

  15. Ohmic Contacts on Diamond by R. F. Sputtering and Ti-Au Metallization

    Science.gov (United States)

    Wang, Y. Y.; Zhen, C. M.; Yan, Z. J.; Guo, Q. F.; Chen, G. H.

    Low resistance ohmic contacts were fabricated on diamond films. A high boron concentration (~1020cm-3) was obtained on the surface by ion implantation. The initial film of Ti (20nm) followed by Au (100nm) was deposited by r. f. sputtering. I-V measurements showed that the as-deposited contacts were ohmic. Upon annealing, the ohmic characteristics of the contacts were improved significantly. The specific contacts resistivity decreased from 6.2 × 10-3 to 1.2 × 10-6Ωcm2 as a result of post-deposition annealing. The X-ray photoelectron spectroscopy analysis indicated the formation of titanium carbide at the Ti/diamond interface in the as-deposited and annealed states. A low oxygen concentration was observed.

  16. Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

    KAUST Repository

    Bahabry, R. R.

    2016-11-30

    We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.

  17. Error free physically unclonable function with programmed resistive random access memory using reliable resistance states by specific identification-generation method

    Science.gov (United States)

    Tseng, Po-Hao; Hsu, Kai-Chieh; Lin, Yu-Yu; Lee, Feng-Min; Lee, Ming-Hsiu; Lung, Hsiang-Lan; Hsieh, Kuang-Yeu; Chung Wang, Keh; Lu, Chih-Yuan

    2018-04-01

    A high performance physically unclonable function (PUF) implemented with WO3 resistive random access memory (ReRAM) is presented in this paper. This robust ReRAM-PUF can eliminated bit flipping problem at very high temperature (up to 250 °C) due to plentiful read margin by using initial resistance state and set resistance state. It is also promised 10 years retention at the temperature range of 210 °C. These two stable resistance states enable stable operation at automotive environments from -40 to 125 °C without need of temperature compensation circuit. The high uniqueness of PUF can be achieved by implementing a proposed identification (ID)-generation method. Optimized forming condition can move 50% of the cells to low resistance state and the remaining 50% remain at initial high resistance state. The inter- and intra-PUF evaluations with unlimited separation of hamming distance (HD) are successfully demonstrated even under the corner condition. The number of reproduction was measured to exceed 107 times with 0% bit error rate (BER) at read voltage from 0.4 to 0.7 V.

  18. Improved knee extensor strength with resistance training associates with muscle specific miRNAs in older adults.

    Science.gov (United States)

    Zhang, Tan; Birbrair, Alexander; Wang, Zhong-Min; Messi, María L; Marsh, Anthony P; Leng, Iris; Nicklas, Barbara J; Delbono, Osvaldo

    2015-02-01

    Regular exercise, particularly resistance training (RT), is the only therapy known to consistently improve muscle strength and quality (force per unit of mass) in older persons, but there is considerable variability in responsiveness to training. Identifying sensitive diagnostic biomarkers of responsiveness to RT may inform the design of a more efficient exercise regimen to improve muscle strength in older adults. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression. We quantified six muscle specific miRNAs (miR-1, -133a, -133b, -206, -208b and -499) in both muscle tissue and blood plasma, and their relationship with knee extensor strength in seven older (age=70.5 ± 2.5 years) adults before and after 5 months of RT. MiRNAs differentially responded to RT; muscle miR-133b decreased, while all plasma miRNAs tended to increase. Percent changes in knee extensor strength with RT showed strong positive correlations with percent changes in muscle miR-133a, -133b, and -206 and with percent changes in plasma and plasma/muscle miR-499 ratio. Baseline level of plasma or plasma/muscle miR-499 ratio further predicts muscle response to RT, while changes in muscle miR-133a, -133b, and -206 may correlate with muscle TNNT1 gene alternative splicing in response to RT. Our results indicate that RT alters muscle specific miRNAs in muscle and plasma, and that these changes account for some of the variation in strength responses to RT in older adults. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Effect of specific resistance training on readiness to change and self-rated health in the working life

    DEFF Research Database (Denmark)

    Bredahl, Thomas Viskum Gjelstrup; Jönsson, Carina; Andersen, Lars

    Introduction The objective of this study was to investigate the effect of 20 weeks of strengths training on readiness to change and self-rated health, amongst laboratory technicians with industrial repetitive work. Methods A cluster randomised controlled trial was performed with an intervention g...... significant effect of specific resistance training on readiness to change, perhaps because the participants entering the study were already selected on a high preference for exercising.......Introduction The objective of this study was to investigate the effect of 20 weeks of strengths training on readiness to change and self-rated health, amongst laboratory technicians with industrial repetitive work. Methods A cluster randomised controlled trial was performed with an intervention...... changes in readiness to change, self-rated health, strengths and fitness. Results The IG had a statistical significant higher readiness to change after 20 weeks of training compared to baseline, whereas no statistical significance was found for the CG, with mean values of intervention (3.72±1.53 vs. 3...

  20. Formation of Phases and Variation of Area Specific Resistance with Surface Roughness in Oxidized Crofer 22 APU

    International Nuclear Information System (INIS)

    Song, Myoung Youp; Mumm, Daniel R.; Song, Jiyoung; Yoon, Soon-Do

    2014-01-01

    Ferritic stainless steel Crofer 22 APU specimens with various surface roughnesses were prepared by grinding with different grit SiC grinding papers. The samples were then thermally cycled 20 times between 298 K and 1073 K (a total oxygen exposure time of 500 h at 1073 K). Observations of the microstructure, measurements of the area specific resistance (ASR), and analysis of the atomic percentages of elements by energy dispersive X-ray (EDX) spectroscopy were performed. As the grit number of the grinding paper, with which the sample was ground, increased from grit 80 through grit 800, the particle size decreased. The particle sizes of the sample ground with grit 800 and the polished sample were similar. A trench of a Crofer 22 APU sample ground with grit 80 after 120 thermal cycles between 298 K and 1073 K (a total oxygen exposure time of 3000 h at 1073 K), observed by scanning electron microscopy (SEM) after focused ion beam (FIB) milling, exhibited an alloy substrate phase, Cr 2 O 3 layer, and (Cr, Mn) 3 O 4 spinel phase from the inside to the surface of the sample. The Cr 2 O 3 layer was undulated with a thickness of about 3 μm. At the same measuring temperature, the ASR increased as the surface of the sample became rougher. Plots of ln (ASR/T ) versus 1/T for samples ground with grit 120, grit 240, and grit 800 after 20 thermal cycles exhibited good linearity.

  1. Jagged1 contributes to the drug resistance of Jurkat cells in contact with human umbilical cord-derived mesenchymal stem cells.

    Science.gov (United States)

    Yuan, Yin; Lu, Xin; Chen, Xuan; Shao, Hongwei; Huang, Shulin

    2013-10-01

    Notch signaling, which is driven by the Notch1 receptor, plays an essential role in the pathogenesis and stroma-mediated drug resistance of T-cell acute lymphoblastic leukemia (T-ALL). However, little is known about the roles of Notch ligands in the survival or drug resistance of T-ALL cells. In the present study, isolated mesenchymal stem cells (MSCs) from human umbilical cord (hUC) samples, termed hUC-MSCs, were used as stromal cells for the Jurkat T-ALL cell line. The role of the Notch ligand, Jagged1, was assessed in the survival of Jurkat T-ALL cells using this co-culture system. hUC-MSCs and Jurkat cells were observed to express Jagged1. Furthermore, co-culture with hUC-MSCs led to a significant upregulation of Jagged1 and a more significant overexpression of its receptor, Notch1, in the Jurkat cells, indicating that the receptor and ligand pair may play a role in the reciprocal or autonomous activation of the Notch pathway. In addition, a higher level of CD28 expression was observed in the Jurkat cells that were co-cultured with hUC-MSCs. Blocking Jagged1 expression using neutralizing antibodies restored drug-induced apoptosis in the Jurkat cells that were co-cultured with hUC-MSCs, and also increased the drug sensitivity of the Jurkat cells that were cultured alone. By contrast, direct incubation with exogenously recombinant Jagged1 produced the same protective effects in Jurkat cells as those induced by hUC-MSCs. These results indicate a significant role for Jagged1 in hUC-MSC-induced survival and the self-maintenance of the Jurkat T-ALL cell line, making it a potential target for the treatment of human T-ALL.

  2. Overexpression of the dual-specificity phosphatase MKP-4/DUSP-9 protects against stress-induced insulin resistance

    DEFF Research Database (Denmark)

    Emanuelli, Brice; Eberlé, Delphine; Suzuki, Ryo

    2008-01-01

    Insulin resistance, a hallmark of type 2 diabetes and obesity, is associated with increased activity of MAP and stress-activated protein (SAP) kinases, which results in decreased insulin signaling. Our goal was to investigate the role of MAP kinase phosphatase-4 (MKP-4) in modulating this process......, improved glucose intolerance, decreased expression of gluconeogenic and lipogenic genes, and reduced hepatic steatosis. Thus, MKP-4 has a protective effect against the development of insulin resistance through its ability to dephosphorylate and inactivate crucial mediators of stress-induced insulin...... resistance, such as ERK and JNK, and increasing MKP-4 activity might provide a therapy for insulin-resistant disorders....

  3. Specific Detection of Naturally Occurring Hepatitis C Virus Mutants with Resistance to Telaprevir and Boceprevir (Protease Inhibitors) among Treatment-Naïve Infected Individuals

    Science.gov (United States)

    Fonseca-Coronado, Salvador; Escobar-Gutiérrez, Alejandro; Ruiz-Tovar, Karina; Cruz-Rivera, Mayra Yolanda; Rivera-Osorio, Pilar; Vazquez-Pichardo, Mauricio; Carpio-Pedroza, Juan Carlos; Ruíz-Pacheco, Juan Alberto; Cazares, Fernando

    2012-01-01

    The use of telaprevir and boceprevir, both protease inhibitors (PI), as part of the specifically targeted antiviral therapy for hepatitis C (STAT-C) has significantly improved sustained virologic response (SVR) rates. However, different clinical studies have also identified several mutations associated with viral resistance to both PIs. In the absence of selective pressure, drug-resistant hepatitis C virus (HCV) mutants are generally present at low frequency, making mutation detection challenging. Here, we describe a mismatch amplification mutation assay (MAMA) PCR method for the specific detection of naturally occurring drug-resistant HCV mutants. MAMA PCR successfully identified the corresponding HCV variants, while conventional methods such as direct sequencing, endpoint limiting dilution (EPLD), and bacterial cloning were not sensitive enough to detect circulating drug-resistant mutants in clinical specimens. Ultradeep pyrosequencing was used to confirm the presence of the corresponding HCV mutants. In treatment-naïve patients, the frequency of all resistant variants was below 1%. Deep amplicon sequencing allowed a detailed analysis of the structure of the viral population among these patients, showing that the evolution of the NS3 is limited to a rather small sequence space. Monitoring of HCV drug resistance before and during treatment is likely to provide important information for management of patients undergoing anti-HCV therapy. PMID:22116161

  4. Antibacterial surface design - Contact kill

    Science.gov (United States)

    Kaur, Rajbir; Liu, Song

    2016-08-01

    Designing antibacterial surfaces has become extremely important to minimize Healthcare Associated Infections which are a major cause of mortality worldwide. A previous biocide-releasing approach is based on leaching of encapsulated biocides such as silver and triclosan which exerts negative impacts on the environment and potentially contributes to the development of bacterial resistance. This drawback of leachable compounds led to the shift of interest towards a more sustainable and environmentally friendly approach: contact-killing surfaces. Biocides that can be bound onto surfaces to give the substrates contact-active antibacterial activity include quaternary ammonium compounds (QACs), quaternary phosphoniums (QPs), carbon nanotubes, antibacterial peptides, and N-chloramines. Among the above, QACs and N-chloramines are the most researched contact-active biocides. We review the engineering of contact-active surfaces using QACs or N-chloramines, the modes of actions as well as the test methods. The charge-density threshold of cationic surfaces for desired antibacterial efficacy and attempts to combine various biocides for the generation of new contact-active surfaces are discussed in detail. Surface positive charge density is identified as a key parameter to define antibacterial efficacy. We expect that this research field will continue to attract more research interest in view of the potential impact of self-disinfective surfaces on healthcare-associated infections, food safety and corrosion/fouling resistance required on industrial surfaces such as oil pipes and ship hulls.

  5. A Study on Graphene—Metal Contact

    Directory of Open Access Journals (Sweden)

    Hongyu Yu

    2013-03-01

    Full Text Available The contact resistance between graphene and metal electrodes is crucial for the achievement of high-performance graphene devices. In this study, we review our recent study on the graphene–metal contact characteristics from the following viewpoints: (1 metal preparation method; (2 asymmetric conductance; (3 annealing effect; (4 interfaces impact.

  6. Contact chain measurements for ultrathin conducting films

    NARCIS (Netherlands)

    Groenland, A.W.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

    2009-01-01

    Test structures for the electrical characterization of ultrathin conductive (ALD) films are presented based on electrodes on which the ultrathin film is deposited. The contact resistance of the buried electrodes to the ultrathin ALD TiN films is investigated using contact chain structures. This work

  7. A Ser29Leu substitution in the cytosine deaminase Fca1p is responsible for clade-specific flucytosine resistance in Candida dubliniensis.

    LENUS (Irish Health Repository)

    McManus, Brenda A

    2009-11-01

    The population structure of the opportunistic yeast pathogen Candida dubliniensis is composed of three main multilocus sequence typing clades (clades C1 to C3), and clade C3 predominantly consists of isolates from the Middle East that exhibit high-level resistance (MIC(50) > or = 128 microg\\/ml) to the fungicidal agent flucytosine (5FC). The close relative of C. dubliniensis, C. albicans, also exhibits clade-specific resistance to 5FC, and resistance is most commonly mediated by an Arg101Cys substitution in the FUR1 gene encoding uracil phosphoribosyltransferase. Broth microdilution assays with fluorouracil (5FU), the toxic deaminated form of 5FC, showed that both 5FC-resistant and 5FC-susceptible C. dubliniensis isolates exhibited similar 5FU MICs, suggesting that the C. dubliniensis cytosine deaminase (Fca1p) encoded by C. dubliniensis FCA1 (CdFCA1) may play a role in mediating C. dubliniensis clade-specific 5FC resistance. Amino acid sequence analysis of the CdFCA1 open reading frame (ORF) identified a homozygous Ser29Leu substitution in all 12 5FC-resistant isolates investigated which was not present in any of the 9 5FC-susceptible isolates examined. The tetracycline-inducible expression of the CdFCA1 ORF from a 5FC-susceptible C. dubliniensis isolate in two separate 5FC-resistant clade C3 isolates restored susceptibility to 5FC, demonstrating that the Ser29Leu substitution was responsible for the clade-specific 5FC resistance and that the 5FC resistance encoded by FCA1 genes with the Ser29Leu transition is recessive. Quantitative real-time PCR analysis showed no significant difference in CdFCA1 expression between 5FC-susceptible and 5FC-resistant isolates in either the presence or the absence of subinhibitory concentrations of 5FC, suggesting that the Ser29Leu substitution in the CdFCA1 ORF is the sole cause of 5FC resistance in clade C3 C. dubliniensis isolates.

  8. High reflectivity Ohmic contacts to n-GaN utilizing vacuum annealed aluminum

    KAUST Repository

    Yonkee, Benjamin P.

    2017-10-31

    Ohmic contacts to both c-plane and (202 ̅1 ̅) n-GaN are demonstrated using a pure aluminum layer which was vacuum annealed to prevent oxidation. Specific contact resistivities of 4.4 × 10-7 and 2.3 × 10-5 Ωcm2 were obtained without annealing for c-plane and (202 ̅1 ̅ ) samples respectively. A reflectivity of over 85% at 450 nm was measured for both samples. After a 300 °C anneal specific contact resistivities of 1.5 × 10-7 and 1.8 × 10-7 Ωcm2 were obtained for c-plane and (202 ̅1 ̅ ) samples respectively and the reflectivities remained higher than 80%.

  9. Meticillin-resistant Staphylococcus aureus CC398 is an increasing cause of disease in people with no livestock contact in Denmark, 1999 to 2011.

    Science.gov (United States)

    Larsen, Jesper; Petersen, Andreas; Sørum, Marit; Stegger, Marc; van Alphen, Lieke; Valentiner-Branth, Palle; Knudsen, Lisbet Krause; Larsen, Lars Stehr; Feingold, Beth; Price, Lance Bradley; Andersen, Paal Skytt; Larsen, Anders Rhod; Skov, Robert Leo

    2015-01-01

    Livestock constitutes a potential reservoir of meticillin-resistant Staphylococcus aureus isolates belonging to a recently derived lineage within clonal complex 398 (MRSA CC398-IIa). Since its discovery in the early 2000s, this lineage has become a major cause of human disease in Europe, posing a serious public health challenge in countries with intensive livestock production. To retrace the history of human colonisation and infection with MRSA CC398-IIa in Denmark, we conducted a nationwide, retrospective study of MRSA isolates collected from 1999 to 2011. Among 7,429 MRSA isolates screened, we identified 416 MRSA CC398-IIa isolates. Of these, 148 were from people with infections, including 51 from patients reporting no livestock exposure. The first cases of MRSA CC398-IIa infection in Denmark occurred in 2004. Subsequently, the incidence of MRSA CC398-IIa infection showed a linear annual increase of 66% from 2004 to 2011 (from 0.09 to 1.1 per 100,000 person-years). There were clear temporal and spatial relationships between MRSA CC398-IIa-infected patients with and without livestock exposure. These findings suggest substantial dissemination of MRSA CC398-IIa from livestock or livestock workers into the Danish community and underscore the need for strategies to control its spread both on and off the farm.

  10. Meticillin-resistant Staphylococcus aureus CC398 is an increasing cause of disease in people with no livestock contact in Denmark, 1999 to 2011

    Science.gov (United States)

    Larsen, J; Petersen, A; Sørum, M; Stegger, M; van Alphen, L; Valentiner-Branth, P; Knudsen, LK; Larsen, LS; Feingold, B; Price, LB; Andersen, PS; Larsen, AR; Skov, RL

    2016-01-01

    Livestock constitutes a potential reservoir of meticillin-resistant Staphylococcus aureus isolates belonging to a recently derived lineage within clonal complex 398 (MRSA CC398-IIa). Since its discovery in the early 2000s, this lineage has become a major cause of human disease in Europe, posing a serious public health challenge in countries with intensive livestock production. To retrace the history of human colonisation and infection with MRSA CC398-IIa in Denmark, we conducted a nationwide, retrospective study of MRSA isolates collected from 1999 to 2011. Among 7,429 MRSA isolates screened, we identified 416 MRSA CC398-IIa isolates. Of these, 148 were from people with infections, including 51 from patients reporting no livestock exposure. The first cases of MRSA CC398-IIa infection in Denmark occurred in 2004. Subsequently, the incidence of MRSA CC398-IIa infection showed a linear annual increase of 66% from 2004 to 2011 (from 0.09 to 1.1 per 100,000 person-years). There were clear temporal and spatial relationships between MRSA CC398-IIa-infected patients with and without livestock exposure. These findings suggest substantial dissemination of MRSA CC398-IIa from livestock or livestock workers into the Danish community and underscore the need for strategies to control its spread both on and off the farm. PMID:26535590

  11. Comparison of Hydrolytic Resistance of Polyurethanes and Poly(Urethanemethacrylate Copolymers in Terms of their Use as Polymer Coatings in Contact with the Physiological Liquid

    Directory of Open Access Journals (Sweden)

    Król Piotr

    2014-06-01

    Full Text Available PU elastomers were synthesized using MDI, PTMO, butane-1,4-diol or 2,2,3,3-tetrafiuorobutane-1,4-diol. Using the same diisocyanate and polyether reagents urethane segments were prepared, to be inserted in the poly(urethane-methacrylate copolymers. Bromourethane or tetraphenylethane-urethane macroinitiators were used as transitional products reacting with MMA according to the ARGET ATRP. 1H and 13C NMR spectral methods, as well as DSC and TGA thermal methods, were employed to confirm chemical structures of synthesised elastomers and copolymers. To investigate the possibility of using synthesized polymers as biomaterials a research on keeping them in physiological liquid at 37°C was performed. A loss in weight and ability to sorption of water was determined and by using GPC the molecular weight changes were compared. Additionally, changes in the thermal properties of the samples after exposure in physiological liquid were documented using both the TGA and DSC methods. The studies of surface properties (confocal microscopy and SFE of the obtained polymers were performed. The structure of the polymer chains was defined by NMR. Possible reasons of hydrolysis were discussed, stating that new copolymers are more resistant and polar biomaterials can be less interesting than elastomers.

  12. Sex-specific costs of resistance to the fungal pathogen Ustilago violacea (Microbotryum violaceum) in Silene alba

    NARCIS (Netherlands)

    Biere, A.; Antonovics, J.

    1996-01-01

    Costs of resistance are often invoked to explain the maintenance of polymorphisms for resistance to fungal pathogens in natural plant populations. To investigate such costs, 27 half-sib families of Silene alba, collected from a single host population, were grown in experiment populations in the

  13. Annealing-induced interfacial reactions and the effects on the electrical properties of Ga doped ZnO/CuxS contacts to p-GaN

    International Nuclear Information System (INIS)

    Gu, Wen; Wu, Xingyang; Song, Peng; Zhang, Jianhua

    2015-01-01

    Highlights: • The electrical properties of GZO/CuS x contacts to p-GaN annealed at different temperatures in air have been studied. • Ohmic contacts were formed by annealing the contacts at 500 and 600 °C in air. • The oxygen in air was found to be essential for the formation of ohmic contact. • The possible formation mechanism of the ohmic contacts was illustrated. - Abstract: Ga-doped ZnO (GZO) contacts to p-GaN were investigated by using Cu x S interlayers under different annealing temperatures. It is shown that the GZO/Cu x S contacts annealed at 300 and 400 °C for 3 min in air exhibited non-ohmic characteristics. However, annealing the contacts at 500 and 600 °C in air resulted in linear current–voltage characteristics. The lowest specific contact resistivity of 1.66 × 10 −2 Ω cm 2 was obtained for the contact annealed at 500 °C. To account for the formation mechanism of the ohmic contact, AES and XPS were used to analyze the interfacial properties of the GZO/Cu x S/p-GaN and Cu x S/p-GaN interfaces, respectively. The possible reasons were discussed in detail, suggesting that the interfacial reactions and atomic diffusions are thought to be responsible for forming such a low contact resistance

  14. Crane-Load Contact Sensor

    Science.gov (United States)

    Youngquist, Robert; Mata, Carlos; Cox, Robert

    2005-01-01

    An electronic instrument has been developed as a prototype of a portable crane-load contact sensor. Such a sensor could be helpful in an application in which the load rests on a base in a horizontal position determined by vertical alignment pins (see Figure 1). If the crane is not positioned to lift the load precisely vertically, then the load can be expected to swing once it has been lifted clear of the pins. If the load is especially heavy, large, and/or fragile, it could hurt workers and/or damage itself and nearby objects. By indicating whether the load remains in contact with the pins when it has been lifted a fraction of the length of the pins, the crane-load contact sensor helps the crane operator determine whether it is safe to lift the load clear of the pins: If there is contact, then the load is resting against the sides of the pins and, hence, it may not be safe to lift; if contact is occasionally broken, then the load is probably not resting against the pins, so it should be safe to lift. It is assumed that the load and base, or at least the pins and the surfaces of the alignment holes in the load, are electrically conductive, so the instrument can use electrical contact to indicate mechanical contact. However, DC resistance cannot be used as an indicator of contact for the following reasons: The load and the base are both electrically grounded through cables (the load is grounded through the lifting cable of the crane) to prevent discharge of static electricity. In other words, the DC resistance between the load and the pins is always low, as though they were always in direct contact. Therefore, instead of DC resistance, the instrument utilizes the AC electrical impedance between the pins and the load. The signal frequency used in the measurement is high enough (.1 MHz) that the impedance contributed by the cables and the electrical ground network of the building in which the crane and the base are situated is significantly greater than the contact

  15. Characteristics of the Sliding Electric Contact of Pantograph/Contact Wire Systems in Electric Railways

    Directory of Open Access Journals (Sweden)

    Guangning Wu

    2017-12-01

    Full Text Available The sliding electric contact of pantograph/contact wire systems plays a significant part in the current collection stability and operation life of pantograph/contact wire systems. This paper addresses the evolutionary process of sliding electric contact of pantograph/contact wire systems by analyzing three key characteristics including contact resistance, temperature distribution and microstructure. The influence of electric current on contact resistance was interpreted. Furthermore, the evolution of the spatial temperature distribution of the carbon strip was obtained in the zigzag movement, while the dominant role of electric effect in temperature rise was demonstrated. In the end, the wear morphology differences under pure friction and current-carrying conditions were analyzed. The formation of radial cracks was illustrated and its influenced on the wear process was discussed.

  16. Genome-Wide Identification of Chalcone Reductase Gene Family in Soybean: Insight into Root-Specific GmCHRs and Phytophthora sojae Resistance

    Directory of Open Access Journals (Sweden)

    Caroline J. Sepiol

    2017-12-01

    Full Text Available Soybean (Glycine max [L.] Merr is one of the main grain legumes worldwide. Soybean farmers lose billions of dollars’ worth of yield annually due to root and stem rot disease caused by the oomycete Phytophthora sojae. Many strategies have been developed to combat the disease, however, these methods have proven ineffective in the long term. A more cost effective and durable approach is to select a trait naturally found in soybean that can increase resistance. One such trait is the increased production of phytoalexin glyceollins in soybean. Glyceollins are isoflavonoids, synthesized via the legume-specific branch of general phenylpropanoid pathway. The first key enzyme exclusively involved in glyceollin synthesis is chalcone reductase (CHR which coacts with chalcone synthase for the production of isoliquiritigenin, the precursor for glyceollin biosynthesis. Here we report the identification of 14 putative CHR genes in soybean where 11 of them are predicted to be functional. Our results show that GmCHRs display tissue-specific gene expression, and that only root-specific GmCHRs are induced upon P. sojae infection. Among 4 root-specific GmCHRs, GmCHR2A is located near a QTL that is linked to P. sojae resistance suggesting GmCHR2A as a novel locus for partial resistance that can be utilized for resistance breeding.

  17. Identification of distinct specificity determinants in resistance protein Cf-4 allows construction of a Cf-9 mutant that confers recognition of avirulence protein AVR4

    NARCIS (Netherlands)

    Hoorn, Van der R.A.L.; Roth, R.; Wit, De P.J.G.M.

    2001-01-01

    The tomato resistance genes Cf-4 and Cf-9 confer specific, hypersensitive response-associated recognition of Cladosporium carrying the avirulence genes Avr4 and Avr9, respectively. Cf-4 and Cf-9 encode type I transmembrane proteins with extracellular leucine-rich repeats (LRRs). Compared with Cf-9,

  18. Prostate-specific Antigen Decline After 4 Weeks of Treatment with Abiraterone Acetate and Overall Survival in Patients with Metastatic Castration-resistant Prostate Cancer

    NARCIS (Netherlands)

    Rescigno, P.; Lorente, D.; Bianchini, D.; Ferraldeschi, R.; Kolinsky, M.P.; Sideris, S.; Zafeiriou, Z.; Sumanasuriya, S.; Smith, A.D.; Mehra, N.; Jayaram, A.; Perez-Lopez, R.; Mateo, J.; Parker, C.; Dearnaley, D.P.; Tunariu, N.; Reid, A.; Attard, G.; Bono, J.S. de

    2016-01-01

    BACKGROUND: The availability of multiple new treatments for metastatic castration-resistant prostate cancer (mCRPC) mandates earlier treatment switches in the absence of a response. A decline in prostate-specific antigen (PSA) is widely used to monitor treatment response, but is not validated as an

  19. Optimization of a Laboratory-Developed Test Utilizing Roche Analyte-Specific Reagents for Detection of Staphylococcus aureus, Methicillin-Resistant S. aureus, and Vancomycin-Resistant Enterococcus Species▿

    OpenAIRE

    Mehta, Maitry S.; Paule, Suzanne M.; Hacek, Donna M.; Thomson, Richard B.; Kaul, Karen L.; Peterson, Lance R.

    2008-01-01

    Nasal and perianal swab specimens were tested for detection of Staphylococcus aureus and vancomycin-resistant Enterococcus species (VRE) using a laboratory-developed real-time PCR test and microbiological cultures. The real-time PCR and culture results for S. aureus were similar. PCR had adequate sensitivity, but culture was more specific for the detection of VRE.

  20. Colored Contact Lens Dangers

    Medline Plus

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

  1. Colored Contact Lens Dangers

    Medline Plus

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

  2. Colored Contact Lens Dangers

    Medline Plus

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

  3. A viral resistance gene from common bean functions across plant families and is up-regulated in a non-virus-specific manner.

    Science.gov (United States)

    Seo, Young-Su; Rojas, Maria R; Lee, Jung-Youn; Lee, Sang-Won; Jeon, Jong-Seong; Ronald, Pamela; Lucas, William J; Gilbertson, Robert L

    2006-08-08

    Genes involved in a viral resistance response in common bean (Phaseolus vulgaris cv. Othello) were identified by inoculating a geminivirus reporter (Bean dwarf mosaic virus expressing the green fluorescent protein), extracting RNA from tissue undergoing the defense response, and amplifying sequences with degenerate R gene primers. One such gene (a TIR-NBS-LRR gene, RT4-4) was selected for functional analysis in which transgenic Nicotiana benthamiana were generated and screened for resistance to a range of viruses. This analysis revealed that RT4-4 did not confer resistance to the reporter geminivirus; however, it did activate a resistance-related response (systemic necrosis) to seven strains of Cucumber mosaic virus (CMV) from pepper or tomato, but not to a CMV strain from common bean. Of these eight CMV strains, only the strain from common bean systemically infected common bean cv. Othello. Additional evidence that RT4-4 is a CMV R gene came from the detection of resistance response markers in CMV-challenged leaves of RT4-4 transgenic plants, and the identification of the CMV 2a gene product as the elicitor of the necrosis response. These findings indicate that RT4-4 functions across two plant families and is up-regulated in a non-virus-specific manner. This experimental approach holds promise for providing insights into the mechanisms by which plants activate resistance responses against pathogens.

  4. Use of an allele-specific polymerase chain reaction assay to genotype pyrethroid resistant strains of Boophilus microplus (Acari: Ixodidae).

    Science.gov (United States)

    Guerrero, F D; Davey, R B; Miller, R J

    2001-01-01

    A polymerase chain reaction-based assay was developed to detect the presence of a pyrethroid resistance-associated amino acid substitution in Boophilus microplus (Canestrini). The assay uses a simple method for the extraction of genomic DNA from individual larvae and genotypes individuals for the presence of a Phe-->Ile amino acid substitution in the S6 transmembrane segment of domain III of the para-like sodium channel, clearly distinguishing heterozygotes from homozygotes. High frequencies for this amino acid substitution were found in the Corrales and San Felipe strains, which have target site insensitivity mechanisms for pyrethroid resistance. The Caporal resistant strain contained lower yet substantial numbers of amino acid-substituted alleles. Low amino acid substitution frequencies were found in the susceptible reference Gonzales strain and the Coatzacoalcos strain, which has metabolic esterase-mediated pyrethroid resistance. The amino acid substitution was not found in six other strains that were susceptible to pyrethroids.

  5. Silencing of the major family of NBS-LRR-encoding genes in lettuce results in the loss of multiple resistance specificities.

    Science.gov (United States)

    Wroblewski, Tadeusz; Piskurewicz, Urszula; Tomczak, Anna; Ochoa, Oswaldo; Michelmore, Richard W

    2007-09-01

    The RGC2 gene cluster in lettuce (Lactuca sativa) is one of the largest known families of genes encoding nucleotide binding site-leucine-rich repeat (NBS-LRR) proteins. One of its members, RGC2B, encodes Dm3 which determines resistance to downy mildew caused by the oomycete Bremia lactucae carrying the cognate avirulence gene, Avr3. We developed an efficient strategy for analysis of this large family of low expressed genes using post-transcriptional gene silencing (PTGS). We transformed lettuce cv. Diana (carrying Dm3) using chimeric gene constructs designed to simultaneously silence RGC2B and the GUS reporter gene via the production of interfering hairpin RNA (ihpRNA). Transient assays of GUS expression in leaves accurately predicted silencing of both genes and were subsequently used to assay silencing in transgenic T(1) plants and their offspring. Levels of mRNA were reduced not only for RGC2B but also for all seven diverse RGC2 family members tested. We then used the same strategy to show that the resistance specificity encoded by the genetically defined Dm18 locus in lettuce cv. Mariska is the result of two resistance specificities, only one of which was silenced by ihpRNA derived from RGC2B. Analysis of progeny from crosses between transgenic, silenced tester stocks and lettuce accessions carrying other resistance genes previously mapped to the RGC2 locus indicated that two additional resistance specificities to B. lactucae, Dm14 and Dm16, as well as resistance to lettuce root aphid (Pemphigus bursarius L.), Ra, are encoded by RGC2 family members.

  6. Contribution of Specific Amino Acid Changes in Penicillin Binding Protein 1 to Amoxicillin Resistance in Clinical Helicobacter pylori isolates ▿

    OpenAIRE

    Qureshi, Nadia N.; Morikis, Dimitrios; Schiller, Neal L.

    2010-01-01

    Amoxicillin is commonly used to treat Helicobacter pylori, a major cause of peptic ulcers, stomach cancer, and B-cell mucosa-associated lymphoid tissue lymphoma. Amoxicillin resistance in H. pylori is increasing steadily, especially in developing countries, leading to treatment failures. In this study, we characterize the mechanism of amoxicillin resistance in the U.S. clinical isolate B258. Transformation of amoxicillin-susceptible strain 26695 with the penicillin binding protein 1 gene (pbp...

  7. Exposure to dairy manure leads to greater antibiotic resistance and increased mass-specific respiration in soil microbial communities

    OpenAIRE

    Wepking, C.; Avera, B.; Badgley, B.; Barrett, J. E.; Franklin, J.; Knowlton, K. F.; Ray, Partha P.; Smitherman, C.; Strickland, M. S.

    2017-01-01

    Intensifying livestock production to meet the demands of a growing global population coincides with increases in both the administration of veterinary antibiotics and manure inputs to soils. These trends have the potential to increase antibiotic resistance in soil microbial communities. The effect of maintaining increased antibiotic resistance on soil microbial communities and the ecosystem processes they regulate is unknown. We compare soil microbial communities from paired reference and dai...

  8. Specific adjustments in grapevine leaf proteome discriminating resistant and susceptible grapevine genotypes to Plasmopara viticola

    DEFF Research Database (Denmark)

    Figueiredo, Andreia; Martins, Joana; Sebastiana, Mónica

    2017-01-01

    to photosynthesis and metabolism allowed the discrimination of resistant and susceptible grapevine cultivars prior to P. viticola inoculation. Following inoculation increase of hydrogen peroxide levels, cellular redox regulation, establishment of ROS signalling and plant cell death seem to be key points....... It is believed that plants infected with biotrophic pathogens suppress JA-mediated responses, however recent evidences shown that jasmonic acid signalling pathway in grapevine resistance against Plasmopara viticola. Our results corroborate those evidences and highlight the importance of lipid- signalling...

  9. All-graphene edge contacts

    DEFF Research Database (Denmark)

    Jacobsen, Kåre Wedel; Falkenberg, Jesper Toft; Papior, Nick Rübner

    2016-01-01

    Using ab-initio methods we investigate the possibility of three-terminalgraphene "T-junction" devices and show that these all-graphene edge contactsare energetically feasible when the 1D interface itself is free from foreignatoms. We examine the energetics of various junction structures as a func......Using ab-initio methods we investigate the possibility of three-terminalgraphene "T-junction" devices and show that these all-graphene edge contactsare energetically feasible when the 1D interface itself is free from foreignatoms. We examine the energetics of various junction structures...... to be in therange of 1-10 kΩμm which is comparable to the best contact resistance reportedfor edge-contacted graphene-metal contacts. We conclude that conductingall-carbon T-junctions should be feasible....

  10. Silencing and heterologous expression of ppo-2 indicate a specific function of a single polyphenol oxidase isoform in resistance of dandelion (Taraxacum officinale) against Pseudomonas syringae pv. tomato.

    Science.gov (United States)

    Richter, Carolin; Dirks, Mareike E; Gronover, Christian Schulze; Prüfer, Dirk; Moerschbacher, Bruno M

    2012-02-01

    Dandelion (Taraxacum officinale) possesses an unusually high degree of disease resistance. As this plant exhibits high polyphenol oxidase (PPO) activity and PPO have been implicated in resistance against pests and pathogens, we analyzed the potential involvement of five PPO isoenzymes in the resistance of dandelion against Botrytis cinerea and Pseudomonas syringae pv. tomato. Only one PPO (ppo-2) was induced during infection, and ppo-2 promoter and β-glucuronidase marker gene fusions revealed strong induction of the gene surrounding lesions induced by B. cinerea. Specific RNAi silencing reduced ppo-2 expression only, and concomitantly increased plant susceptibility to P. syringae pv. tomato. At 4 days postinoculation, P. syringae pv. tomato populations were strongly increased in the ppo-2 RNAi lines compared with wild-type plants. When the dandelion ppo-2 gene was expressed in Arabidopsis thaliana, a plant having no PPO gene, active protein was formed and protein extracts of the transgenic plants exhibited substrate-dependent antimicrobial activity against P. syringae pv. tomato. These results clearly indicate a strong contribution of a specific, single PPO isoform to disease resistance. Therefore, we propose that specific PPO isoenzymes be included in a new family of pathogenesis-related (PR) proteins.

  11. Predicting spring barley yield from variety-specific yield potential, disease resistance and straw length, and from environment-specific disease loads and weed pressure

    DEFF Research Database (Denmark)

    Østergård, Hanne; Kristensen, Kristian; Pinnschmidt, Hans O.

    2008-01-01

    For low-input crop production, well-characterised varieties increase the possibilities of managing diseases and weeds. This analysis aims at developing a framework for analyzing grain yield using external varietal information about disease resistance, weed competitiveness and yield potential and ...... growth habit. Higher grain yield was thus predicted for taller plants under weed pressure. The results are discussed in relation to the model framework, impact of the considered traits and use of information from conventional variety testing in organic cropping systems.......For low-input crop production, well-characterised varieties increase the possibilities of managing diseases and weeds. This analysis aims at developing a framework for analyzing grain yield using external varietal information about disease resistance, weed competitiveness and yield potential...... and quantifying the impact of susceptibility grouping and straw length scores (as a measure for weed competitiveness) for predicting spring barley grain yield under variable biotic stress levels. The study comprised 52 spring barley varieties and 17 environments, i.e., combinations of location, growing system...

  12. Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen.

    Directory of Open Access Journals (Sweden)

    Sonja Schmidt

    Full Text Available Prostate-specific membrane antigen (PSMA is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009 PLoS One 4: e4608 we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for

  13. Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen

    Science.gov (United States)

    Schmidt, Sonja; Gericke, Birthe; Fracasso, Giulio; Ramarli, Dunia; Colombatti, Marco; Naim, Hassan Y.

    2013-01-01

    Prostate-specific membrane antigen (PSMA) is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs) along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009) PLoS One 4: e4608) we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for utilization of PSMA as

  14. [Correct contact lens hygiene].

    Science.gov (United States)

    Blümle, S; Kaercher, T; Khaireddin, R

    2013-06-01

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

  15. Investigating the Effects of Regular Resistance Training and Prostatic Massage on Proinflammatory Markers and Serum Prostate-Specific Antigen Levels in Males with Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Fathollahi Shoorabeh

    2016-01-01

    Full Text Available Background Prostate cancer (PC is one of the most common cancers worldwide. Some studies support that chronic inflammation of prostate tissue plays a role in the development of PC. A variety of growth factors and cytokines may lead to proinflammatory processes within the prostate. Objectives The aim of the present study was to investigate the effects of eight weeks of regular resistance training and prostatic massage on proinflammatory markers CRP, IL-6, TNF-α, and IL-10 and serum prostate-specific antigen (PSA levels in males with PC. Patients and Methods Forty-five patients with PC were selected for this study. They were randomized into either the resistance training intervention group (n = 15, the massage intervention group (n = 15, or the control group (n = 15. Resistance-training patients participated in resistance training for eight weeks, and massage was performed for six weeks on the massage group. Repeated measures analysis of variance (ANOVA was used to analyze the data (P ≤ 0.05. Results In the resistance training group, IL-10 levels significantly increased after four (P = 0.055 and eight weeks (P = 0.000. Four and eight weeks of resistance training showed a significant reduction in PSA, CRP, IL-6, and TNF-α levels (P < 0.05. Patients of massage intervention showed an increase in IL-10 after four (P = 0.045 and six weeks (P = 0.005. In addition, four and six weeks of massage intervention showed a significant reduction in PSA, CRP, IL-6, and TNF-α levels (P < 0.05. Conclusions Regular resistance training and prostatic massage can improve proinflammatory markers and PSA levels in men with PC.

  16. Over-representation of specific regions of chromosome 22 in cells from human glioma correlate with resistance to 1,3-bis(2-chloroethyl-1-nitrosourea

    Directory of Open Access Journals (Sweden)

    Scheck Adrienne C

    2006-01-01

    Full Text Available Abstract Background Glioblastoma multiforme is the most malignant form of brain tumor. Despite treatment including surgical resection, adjuvant chemotherapy, and radiation, these tumors typically recur. The recurrent tumor is often resistant to further therapy with the same agent, suggesting that the surviving cells that repopulate the tumor mass have an intrinsic genetic advantage. We previously demonstrated that cells selected for resistance to 1,3-bis(2-chloroethyl-1-nitrosourea (BCNU are near-diploid, with over-representation of part or all of chromosomes 7 and 22. While cells from untreated gliomas often have over-representation of chromosome 7, chromosome 22 is typically under-represented. Methods We have analyzed cells from primary and recurrent tumors from the same patient before and after in vitro selection for resistance to clinically relevant doses of BCNU. Karyotypic analyses were done to demonstrate the genetic makeup of these cells, and fluorescent in situ hybridization analyses have defined the region(s of chromosome 22 retained in these BCNU-resistant cells. Results Karyotypic analyses demonstrated that cells selected for BCNU resistance were near-diploid with over-representation of chromosomes 7 and 22. In cells where whole copies of chromosome 22 were not identified, numerous fragments of this chromosome were retained and inserted into several marker and derivative chromosomes. Fluorescent in situ hybridization analyses using whole chromosome paints confirmed this finding. Additional FISH analysis using bacterial artificial chromosome probes spanning the length of chromosome 22 have allowed us to map the over-represented region to 22q12.3–13.32. Conclusion Cells selected for BCNU resistance either in vivo or in vitro retain sequences mapped to chromosome 22. The specific over-representation of sequences mapped to 22q12.3–13.32 suggest the presence of a DNA sequence important to BCNU survival and/or resistance located in

  17. The MLA6 coiled-coil, NBS-LRR protein confers AvrMla6-dependent resistance specificity to Blumeria graminis f. sp. hordei in barley and wheat.

    Science.gov (United States)

    Halterman, D; Zhou, F; Wei, F; Wise, R P; Schulze-Lefert, P

    2001-02-01

    The barley Mla locus confers multiple resistance specificities to the obligate fungal biotroph, Blumeria (= Erysiphe) graminis f. sp. hordei. Interspersed within the 240 kb Mla complex are three families of resistance gene homologs (RGHs). Probes from the Mla-RGH1 family were used to identify three classes of cDNAs. The first class is predicted to encode a full-length CC-NBS-LRR protein and the other two classes contain alternatively spliced, truncated variants. Utilizing a cosmid that contains a gene corresponding to the full-length candidate cDNA, two single-cell expression assays were used to demonstrate complementation of AvrMla6-dependent, resistance specificity to B. graminis in barley and wheat. The first of these assays was also used to substantiate previous genetic data that the Mla6 allele requires the signaling pathway component, Rar1, for function. Computational analysis of MLA6 and the Rar1-independent, MLA1 protein reveals 91.2% identity and shows that the LRR domain is subject to diversifying selection. Our findings demonstrate that highly related CC-NBS-LRR proteins encoded by alleles of the Mla locus can dictate similar powdery mildew resistance phenotypes yet still require distinct downstream signaling components.

  18. Mechanoluminescent Contact Type Sensor

    Directory of Open Access Journals (Sweden)

    A. K. Yefremov

    2017-01-01

    Full Text Available Mechanoluminescent sensing elements convert mechanical stress into optical radiation. Advantages of such sensors are the ability to generate an optical signal, solid-state, simple structure, and resistance to electromagnetic interference. Mechanoluminescent sensor implementations can possess the concentrated and distributed sensitivity, thereby allowing us to detect the field of mechanical stresses distributed across the area and in volume. Most modern semiconductor photo-detectors can detect mechanoluminescent radiation, so there are no difficulties to provide its detection when designing the mechanoluminescent sensing devices. Mechanoluminescent substances have especial sensitivity to shock loads, and this effect can be used to create a fuse the structure of which includes a target contact type sensor with a photosensitive actuator. The paper briefly describes the theoretical basics of mechanoluminiscence: a light signal emerges from the interaction of crystalline phosphor luminescence centers with electrically charged dislocations, moving due to the deformation of the crystal. A mathematical model of the mechanoluminescent conversion is represented as a functional interaction between parameters of the mechanical shock excitation and the sensor light emission. Examples of computing the optical mechanoluminescent output signal depending on the duration and peak level of impulse load are given. It is shown that the luminous flux, generated by mechanoluminescent sensing element when there is an ammunition-target collision causes the current emerging in photo-detector (photodiode that is sufficient for a typical actuator of the fuse train to operate. The potential possibility to create a contact target type sensor based on the light-sensitive mechanoluminescent sensor was proved by the calculation and simulation results.

  19. Decrease in electrical contact resistance of Sb-doped n+-BaSi2 layers and spectral response of an Sb-doped n+-BaSi2/undoped BaSi2 structure for solar cells

    Science.gov (United States)

    Kodama, Komomo; Takabe, Ryota; Yachi, Suguru; Toko, Kaoru; Suemasu, Takashi

    2018-03-01

    We investigated how the electron concentration n in a 300-nm-thick Sb-doped n+-BaSi2 layer grown by molecular beam epitaxy affected the contact resistance R C to surface electrodes (Al, indium-tin-oxide). As the n of n-BaSi2 increased, R C decreased and reached a minimum of 0.019 Ω cm2 at n = 2.4 × 1018 cm-3 for the Al electrodes. This value was more than 1 order of magnitude smaller than that obtained for Al/B-doped p-BaSi2. We believe that this significant decrease in R C came from Sb segregation. Furthermore, the internal quantum efficiency (IQE) spectrum was evaluated for an Sb-doped n+-BaSi2 (20 nm)/undoped BaSi2 (500 nm)/n+-Si(111) structure. Its IQE reached as high as ˜50% over a wide wavelength range under a small bias voltage of 0.1 V applied between the top and bottom electrodes.

  20. Dissemination of Cephalosporin Resistance Genes between Escherichia coli Strains from Farm Animals and Humans by Specific Plasmid Lineages

    NARCIS (Netherlands)

    de Been, Mark; Lanza, Val F.; de Toro, María; Scharringa, Jelle; Dohmen, Wietske|info:eu-repo/dai/nl/333690451; Du, Yu; Hu, Juan; Lei, Ying; Li, Ning; Tooming-Klunderud, Ave; Heederik, Dick J J|info:eu-repo/dai/nl/072910542; Fluit, Ad C.; Bonten, Marc J M; Willems, Rob J L; de la Cruz, Fernando; van Schaik, Willem

    2014-01-01

    Third-generation cephalosporins are a class of β-lactam antibiotics that are often used for the treatment of human infections caused by Gram-negative bacteria, especially Escherichia coli. Worryingly, the incidence of human infections caused by third-generation cephalosporin-resistant E. coli is

  1. Palisade Russet: A late blight resistant potato cultivar having a low incidence of sugar ends and high specific gravity

    Science.gov (United States)

    Palisade Russet is a medium-late maturing, lightly russeted potato breeding clone notable for its resistance to late blight (Phytophthora infestans) infection of foliage and tuber. Palisade Russet is suitable for processing with low tuber glucose concentrations observed following long-term storage ...

  2. Comparison of Lower Body Specific Resistance Training on the Hamstring to Quadriceps Strength Ratios in Men and Women

    Science.gov (United States)

    Dorgo, Sandor; Edupuganti, Pradeep; Smith, Darla R.; Ortiz, Melchor

    2012-01-01

    In this study, we compared hamstring (H) and quadriceps (Q) strength changes in men and women, as well as changes in conventional and functional H:Q ratios following an identical 12-week resistance training program. An isokinetic dynamometer was used to assess 14 male and 14 female participants before and after the intervention, and conventional…

  3. Development of laser-fired contacts for amorphous silicon layers obtained by Hot-Wire CVD

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, D. [XaRMAE-Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Diagonal 647, Barcelona 08028 (Spain)], E-mail: delfina@eel.upc.edu; Voz, C.; Blanque, S. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain); Ibarz, D.; Bertomeu, J. [XaRMAE-Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Diagonal 647, Barcelona 08028 (Spain); Alcubilla, R. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain)

    2009-03-15

    In this work we study aluminium laser-fired contacts for intrinsic amorphous silicon layers deposited by Hot-Wire CVD. This structure could be used as an alternative low temperature back contact for rear passivated heterojunction solar cells. An infrared Nd:YAG laser (1064 nm) has been used to locally fire the aluminium through the thin amorphous silicon layers. Under optimized laser firing parameters, very low specific contact resistances ({rho}{sub c} {approx} 10 m{omega} cm{sup 2}) have been obtained on 2.8 {omega} cm p-type c-Si wafers. This investigation focuses on maintaining the passivation quality of the interface without an excessive increase in the series resistance of the device.

  4. Development of laser-fired contacts for amorphous silicon layers obtained by Hot-Wire CVD

    International Nuclear Information System (INIS)

    Munoz, D.; Voz, C.; Blanque, S.; Ibarz, D.; Bertomeu, J.; Alcubilla, R.

    2009-01-01

    In this work we study aluminium laser-fired contacts for intrinsic amorphous silicon layers deposited by Hot-Wire CVD. This structure could be used as an alternative low temperature back contact for rear passivated heterojunction solar cells. An infrared Nd:YAG laser (1064 nm) has been used to locally fire the aluminium through the thin amorphous silicon layers. Under optimized laser firing parameters, very low specific contact resistances (ρ c ∼ 10 mΩ cm 2 ) have been obtained on 2.8 Ω cm p-type c-Si wafers. This investigation focuses on maintaining the passivation quality of the interface without an excessive increase in the series resistance of the device.

  5. 4H-SiC Power Bipolar Junction Transistor with a Very Low Specific On-resistance of 2.9 mOmega.cm2

    Science.gov (United States)

    2006-04-12

    specific on-resistance (Rsp,on) of power 4H-SiC bipolar junction transistors ( BJT ). A 4H-SiC BJT based on a 12 um drift-layer shows a record low...reported for high power 4H-SiC BJTs . Index Terms—Silicon carbide, bipolar junction transistors ( BJTs ), power transistors ...bipolar junction transistor ( BJT ) is an important switching device for high power and high temperature applications, which is an intrinsically

  6. Reducing Contact Resistance Errors In Measuring Thermal ...

    African Journals Online (AJOL)

    Values of thermal conductivity (k) of glass beads, quartz sand, stone dust and clay were determined using a thermal probe with and without heat sink compounds (arctic silver grease (ASG) and white grease (WG)) at different water contents, bulk densities and particle sizes. The heat sink compounds (HSC) increased k at ...

  7. Insulin Resistance and Prediabetes

    Science.gov (United States)

    ... in the normal range. What happens with insulin resistance? In insulin resistance, muscle, fat, and liver cells do not ... they do not usually test specifically for insulin resistance. Insulin resistance can be assessed by measuring the level ...

  8. Fiber type specific response of skeletal muscle satellite cells to high-intensity resistance training in dialysis patients

    DEFF Research Database (Denmark)

    Molsted, Stig; Andersen, Jesper Løvind; Harrison, Adrian Paul

    2015-01-01

    weekly. SC and myonuclear number were determined by immunohistochemistry of vastus lateralis muscle biopsy cross-sections. Knee extension torque was tested in a dynamometer. Results. During training SCs/type I fibers increased by 15%, whereas SCs/type II fibers remained unchanged. Myonuclear content......Introduction. The aim was to investigate the effect of high-intensity resistance training on satellite cell (SC) and myonuclear number in the muscle of patients undergoing dialysis. Methods. Patients (n=21) underwent a 16-week control period, followed by 16 weeks of resistance training thrice...... of type II, but not type I, fibers increased with training. Before the control period, the SC content of type II fibers was lower than type I fibers, whereas contents were comparable when normalized to fiber area. Torque increased after training. Discussion. Increased myonuclear content of type II muscle...

  9. Reversible lysine-specific demethylase 1 antagonist HCI-2509 inhibits growth and decreases c-MYC in castration- and docetaxel-resistant prostate cancer cells.

    Science.gov (United States)

    Gupta, S; Weston, A; Bearrs, J; Thode, T; Neiss, A; Soldi, R; Sharma, S

    2016-12-01

    Lysine-specific demethylase 1 (LSD1 or KDM1A) overexpression correlates with poor survival and castration resistance in prostate cancer. LSD1 is a coregulator of ligand-independent androgen receptor signaling promoting c-MYC expression. We examined the antitumor efficacy of LSD1 inhibition with HCI-2509 in advanced stages of prostate cancer. Cell survival, colony formation, histone methylation, c-MYC level, c-MYC expression, cell cycle changes and in vivo efficacy were studied in castration-resistant prostate cancer cells upon treatment with HCI-2509. In vitro combination studies, using HCI-2509 and docetaxel, were performed to assess the synergy. Cell survival, colony formation, histone methylation and c-myc levels were studied in docetaxel-resistant prostate cancer cells treated with HCI-2509. HCI-2509 is cytotoxic and inhibits colony formation in castration-resistant prostate cancer cells. HCI-2509 treatment causes a dose-dependent increase in H3K9me2 (histone H3lysine 9) levels, a decrease in c-MYC protein, inhibition of c-MYC expression and accumulation in the G0/G1 phase of the cell cycle in these cells. PC3 xenografts in mice have a significant reduction in tumor burden upon treatment with HCI-2509 with no associated myelotoxicity or weight loss. More synergy is noted at sub-IC 50 (half-maximal inhibitory concentration) doses of docetaxel and HCI-2509 in PC3 cells than in DU145 cells. HCI-2509 has growth-inhibitory efficacy and decreases the c-myc level in docetaxel-resistant prostate cancer cells. LSD1 inhibition with HCI-2509 decreases the c-MYC level in poorly differentiated prostate cancer cell lines and has a therapeutic potential in castration- and docetaxel-resistant prostate cancer.

  10. The Salmonella genomic island 1 is specifically mobilized in trans by the IncA/C multidrug resistance plasmid family.

    Science.gov (United States)

    Douard, Gregory; Praud, Karine; Cloeckaert, Axel; Doublet, Benoît

    2010-12-20

    The Salmonella genomic island 1 (SGI1) is a Salmonella enterica-derived integrative mobilizable element (IME) containing various complex multiple resistance integrons identified in several S. enterica serovars and in Proteus mirabilis. Previous studies have shown that SGI1 transfers horizontally by in trans mobilization in the presence of the IncA/C conjugative helper plasmid pR55. Here, we report the ability of different prevalent multidrug resistance (MDR) plasmids including extended-spectrum β-lactamase (ESBL) gene-carrying plasmids to mobilize the multidrug resistance genomic island SGI1. Through conjugation experiments, none of the 24 conjugative plasmids tested of the IncFI, FII, HI2, I1, L/M, N, P incompatibility groups were able to mobilize SGI1 at a detectable level (transfer frequency IncA/C incompatibility group. Several conjugative IncA/C MDR plasmids as well as the sequenced IncA/C reference plasmid pRA1 of 143,963 bp were shown to mobilize in trans SGI1 from a S. enterica donor to the Escherichia coli recipient strain. Depending on the IncA/C plasmid used, the conjugative transfer of SGI1 occurred at frequencies ranging from 10(-3) to 10(-6) transconjugants per donor. Of particular concern, some large IncA/C MDR plasmids carrying the extended-spectrum cephalosporinase bla(CMY-2) gene were shown to mobilize in trans SGI1. The ability of the IncA/C MDR plasmid family to mobilize SGI1 could contribute to its spread by horizontal transfer among enteric pathogens. Moreover, the increasing prevalence of IncA/C plasmids in MDR S. enterica isolates worldwide has potential implications for the epidemic success of the antibiotic resistance genomic island SGI1 and its close derivatives.

  11. Proteomics analysis of 3 different strains of Mycobacterium tuberculosis under in vitro hypoxia and evaluation of hypoxia associated antigen’s specific memory T cells in healthy household contacts

    Directory of Open Access Journals (Sweden)

    Santhi Devasundaram

    2016-09-01

    Full Text Available In vitro mimicking conditions are thought to reflect the environment experienced by M. tuberculosis inside the host granuloma. The majority of the in vitro dormancy experimental models used laboratory adapted strain H37Rv or Erdman strain over the prevalent clinical strains involved during disease outbreaks. Thus, we included the most prevalent clinical strains (S7 and S10 of M. tuberculosis from south India in addition to H37Rv for our in vitro oxygen depletion (hypoxia experimental model. Cytosolic proteins were prepared from the hypoxic cultures, resolved by two-dimensional electrophoresis (2-DE and protein spots were characterized by mass spectrometry. Totally 49 spots were characterized as over-expressed or newly appeared between the 3 strains. Two antigens (ESAT-6, Lpd out of the 49 characterized spots were readily available in recombinant form in our lab. Hence, these 2 genes were overexpressed, purified and used for in vitro stimulation of whole blood collected from healthy household contacts (HHC and active pulmonary tuberculosis patients (PTB. Multicolour flow cytometry analysis showed high levels of antigen specific CD4+ central memory T cells in circulation of HHC when compared to PTB (p<0.005 for ESAT-6 and p<0.0005 for Lpd. This shows proteins that are predicted to be upregulated during in vitro hypoxia in most prevalent clinical strains would bring the possible potential immunogens. In vitro hypoxia experiments with most prevalent clinical strains would also bring the probable true representative antigens that involved during adaption mechanism.

  12. Evidence against the existence of specific Schistosoma mansoni subpopulations which are resistant to irradiated vaccine-induced immunity

    International Nuclear Information System (INIS)

    Lewis, F.A.; Hieny, S.; Sher, A.

    1985-01-01

    When mice are immunized with irradiated Schistosoma mansoni cercariae a proportion of the subsequent cercarial challenge always escapes killing and matures to egg-laying adults. This report investigates the possibility that incomplete immunity in this system is governed by a genetically-determined insusceptibility of a particular schistosome subpopulation. To do this the authors tested whether more immunoresistant schistosomes would develop following successive passages of progeny of the resistant worms through immunized mice. Mice were immunized with 500 50 Krad-irradiated cercariae, and challenged with normal cercariae when immunity was at its peak. After five successive passages through snails and immune mice, progeny of those parasites which escaped immune killing were no more refractory to vaccine-induced resistance than the original stock maintained in nonimmune mice. Additionally, the passaged isolates did not differ from the original stock in their ability to induce protection following irradiation. The results indicate that with this model of acquired resistance incomplete immunity is unlikely to be due to a subpopulation of the parasites possessing a genetically-determined insusceptibility to killing

  13. Dominant incidence of multidrug and extensively drug-resistant specific Mycobacterium tuberculosis clones in Osaka Prefecture, Japan.

    Directory of Open Access Journals (Sweden)

    Aki Tamaru

    Full Text Available Infection and transmission of multidrug-resistant Mycobacterium tuberculosis (MDR-Mtb and extensively drug-resistant M. tuberculosis (XDR-Mtb is a serious health problem. We analyzed a total of 1,110 Mtb isolates in Osaka Prefecture and neighboring areas from April 2000 to March 2009. A total of 89 MDR-Mtb were identified, 36 (48.5% of which were determined to be XDR-Mtb. Among the 89 MDR-Mtb isolates, 24 (27.0% phylogenetically distributed into six clusters based on mycobacterial interspersed repetitive units-various number of tandem repeats (MIRU-VNTR typing. Among these six clusters, the MIRU-VNTR patterns of four (OM-V02, OM-V03, OM-V04, and OM-V06 were only found for MDR-Mtb. Further analysis revealed that all isolates belonging to OM-V02 and OM-V03, and two isolates from OM-V04 were clonal. Importantly such genotypes were not observed for drug-sensitive isolates. These suggest that few but transmissible clones can transmit after acquiring multidrug resistance and colonize even in a country with a developed, well-organized healthcare system.

  14. Hair dye contact allergy

    DEFF Research Database (Denmark)

    Søsted, Heidi; Rastogi, Suresh Chandra; Andersen, Klaus Ejner

    2004-01-01

    Colouring of hair can cause severe allergic contact dermatitis. The most frequently reported hair dye allergens are p-phenylenediamine (PPD) and toluene-2,5-diamine, which are included in, respectively, the patch test standard series and the hairdressers series. The aim of the present study...... was to identify dye precursors and couplers in hair dyeing products causing clinical hair dye dermatitis and to compare the data with the contents of these compounds in a randomly selected set of similar products. The patient material comprised 9 cases of characteristic clinical allergic hair dye reaction, where...... exposure history and patch testing had identified a specific hair dye product as the cause of the reaction. The 9 products used by the patients were subjected to chemical analysis. 8 hair dye products contained toluene-2,5-diamine (0.18 to 0.98%). PPD (0.27%) was found in 1 product, and m-aminophenol (0...

  15. Effect of poly-hexamethylene biguanide hydrochloride (PHMB) treated non-sterile medical gloves upon the transmission of Streptococcus pyogenes, carbapenem-resistant E. coli, MRSA and Klebsiella pneumoniae from contact surfaces.

    Science.gov (United States)

    Ali, S; Wilson, A P R

    2017-08-17

    Reduction of accidental contamination of the near-patient environment has potential to reduce acquisition of healthcare-associated infection(s). Although medical gloves should be removed when soiled or touching the environment, compliance is variable. The use of antimicrobial-impregnated medical gloves could reduce the horizontal-transfer of bacterial contamination between surfaces. Determine the activity of antimicrobial-impregnated gloves against common hospital pathogens: Streptococcus pyogenes, carbapenem-resistant E.coli (CREC), MRSA and ESBL-producing Klebsiella pneumoniae. Fingerpads (~1cm 2 ) of PHMB-treated and untreated gloves were inoculated with 10 μL (~10 4 colony-forming-units [cfu]) of test-bacteria prepared in heavy-soiling (0.5%BSA), blood or distilled-water (no-soiling) and sampled after 0.25, 1, 10 or 15 min contact-time. Donor surfaces (~1cm 2 computer-keys) contaminated with wet/dry inoculum were touched with the fingerpad of treated/untreated gloves and subsequently pressed onto recipient (uncontaminated) computer-keys. Approximately 4.50log 10 cfu of all bacteria persisted after 15 min on untreated gloves regardless of soil-type. In the absence of soiling, PHMB-treated gloves reduced surface-contamination by ~4.5log 10 cfu (>99.99%) within 10 min of contact-time but only ~2.5log 10 (>99.9%) and ~1.0log 10 reduction respectively when heavy-soiling or blood was present. Gloves became highly-contaminated (~4.52log 10 -4.91log 10 cfu) when handling recently-contaminated computer-keys. Untreated gloves contaminated "recipient" surfaces (~4.5log 10 cfu) while PHMB-treated gloves transferred fewer bacteria (2.4-3.6log 10 cfu). When surface contamination was dry, PHMB gloves transferred fewer bacteria (0.3-0.6log 10 cfu) to "recipient" surfaces than untreated gloves (1.0-1.9log 10 ; P gloves may be useful in preventing dissemination of organisms in the near-patient environment during routine care. However they are not a substitute for

  16. Botrytis fragariae, a New Species Causing Gray Mold on Strawberries, Shows High Frequencies of Specific and Efflux-Based Fungicide Resistance

    Science.gov (United States)

    Rupp, Sabrina; Plesken, Cecilia; Rumsey, Sibylle; Dowling, Madeline; Schnabel, Guido; Weber, Roland W. S.

    2017-01-01

    ABSTRACT Botrytis cinerea causes pre- and postharvest decay of many fruit and vegetable crops. A survey of German strawberry fields revealed Botrytis strains that differed from B. cinerea in diagnostic PCR markers and growth appearance. Phylogenetic analyses showed that these strains belong to an undescribed species in Botrytis clade 2, named Botrytis fragariae sp. nov. Isolates of B. fragariae were detected in strawberry fields throughout Germany, sometimes at frequencies similar to those of B. cinerea, and in the southeastern United States. B. fragariae was isolated from overwintering strawberry tissue but not from freshly infected fruit. B. fragariae invaded strawberry tissues with an efficiency similar to or lower than that of B. cinerea but showed poor colonization of inoculated nonhost plant tissues. These data and the exclusive occurrence of this fungus on strawberry plants indicate that B. fragariae is host specific and has a tissue preference different from that of B. cinerea. Various fungicide resistance patterns were observed in B. fragariae populations. Many B. fragariae strains showed resistance to one or several chemical classes of fungicides and an efflux-based multidrug resistance (MDR1) phenotype previously described in B. cinerea. Resistance-related mutations in B. fragariae were identical or similar to those of B. cinerea for carbendazim (E198A mutation in tubA), azoxystrobin (G143A in cytB), iprodione (G367A+V368F in bos1), and MDR1 (gain-of-function mutations in the transcription factor mrr1 gene and overexpression of the drug efflux transporter gene atrB). The widespread occurrence of B. fragariae indicates that this species is adapted to fungicide-treated strawberry fields and may be of local importance as a gray mold pathogen alongside B. cinerea. IMPORTANCE Gray mold is the most important fruit rot on strawberries worldwide and requires fungicide treatments for control. For a long time, it was believed to be caused only by Botrytis cinerea

  17. Botrytis fragariae, a New Species Causing Gray Mold on Strawberries, Shows High Frequencies of Specific and Efflux-Based Fungicide Resistance.

    Science.gov (United States)

    Rupp, Sabrina; Plesken, Cecilia; Rumsey, Sibylle; Dowling, Madeline; Schnabel, Guido; Weber, Roland W S; Hahn, Matthias

    2017-05-01

    Botrytis cinerea causes pre- and postharvest decay of many fruit and vegetable crops. A survey of German strawberry fields revealed Botrytis strains that differed from B. cinerea in diagnostic PCR markers and growth appearance. Phylogenetic analyses showed that these strains belong to an undescribed species in Botrytis clade 2, named Botrytis fragariae sp. nov. Isolates of B fragariae were detected in strawberry fields throughout Germany, sometimes at frequencies similar to those of B. cinerea , and in the southeastern United States. B fragariae was isolated from overwintering strawberry tissue but not from freshly infected fruit. B fragariae invaded strawberry tissues with an efficiency similar to or lower than that of B. cinerea but showed poor colonization of inoculated nonhost plant tissues. These data and the exclusive occurrence of this fungus on strawberry plants indicate that B fragariae is host specific and has a tissue preference different from that of B. cinerea Various fungicide resistance patterns were observed in B fragariae populations. Many B fragariae strains showed resistance to one or several chemical classes of fungicides and an efflux-based multidrug resistance (MDR1) phenotype previously described in B. cinerea Resistance-related mutations in B fragariae were identical or similar to those of B. cinerea for carbendazim (E198A mutation in tubA ), azoxystrobin (G143A in cytB ), iprodione (G367A+V368F in bos1 ), and MDR1 (gain-of-function mutations in the transcription factor mrr1 gene and overexpression of the drug efflux transporter gene atrB ). The widespread occurrence of B fragariae indicates that this species is adapted to fungicide-treated strawberry fields and may be of local importance as a gray mold pathogen alongside B. cinerea IMPORTANCE Gray mold is the most important fruit rot on strawberries worldwide and requires fungicide treatments for control. For a long time, it was believed to be caused only by Botrytis cinerea , a ubiquitous

  18. Colored Contact Lens Dangers

    Medline Plus

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

  19. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... sell contacts without a prescription are breaking the law, and may be fined $11,000 per violation. " ... wear any kind of contact lens. In Butler's case, the lenses caused an infection and left her ...

  20. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... Academy Jobs at the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For ...

  1. Colored Contact Lens Dangers

    Medline Plus

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

  2. Contact Angle Goniometer

    Data.gov (United States)

    Federal Laboratory Consortium — Description:The FTA32 goniometer provides video-based contact angle and surface tension measurement. Contact angles are measured by fitting a mathematical expression...

  3. Multiple Josephson contact interferometer

    International Nuclear Information System (INIS)

    Zappe, H.H.

    1978-01-01

    The interferometer (quantum interference between two parallel contacts) displays a mid connector and contacts of the same size, or contacts at which the middle one is twice the size as the other two, or a double connector and three contacts by which the middle contact carries twice the current as the other two. Also there can be provided interferometers with three and four contacts as well as with symmetrical double current connectors and the same largest Josephson current through all contacts. Because all contacts display the same phase state in the voltage free switching state, the amplification property can be increased and current dissipation can be decreased in a way that logic circuits with high integration degree and high switching velocities can be designed. (DG) [de

  4. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Cleveland. "This is far from the truth." Real People, Real Problems with Colored Contact Lenses Julian: Teenager ... the lenses. Never share contact lenses with another person. Get follow up exams with your eye care ...

  5. Colored Contact Lens Dangers

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    Full Text Available ... popping touch. But colored contact lenses are popular year-round, not just at Halloween. But few know the ... also available in Spanish . Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About ...

  6. Colored Contact Lens Dangers

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

  7. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... Costume Contacts May Contain Chemicals Harmful to Eyes Four Ways Over-the-Counter Costume Contact Lenses Can ... was in severe pain and on medication for four weeks, and couldn't see well enough to ...

  8. Corporate Consumer Contact API

    Data.gov (United States)

    General Services Administration — The data in the Corporate Consumer Contact API is based on the content you can find in the Corporate Consumer Contact listing in the Consumer Action Handbook (PDF)....

  9. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... not require the same level of care or consideration as a standard contact lens because they can ... sell contacts without a prescription are breaking the law, and may be fined $11,000 per violation. " ...

  10. Colored Contact Lens Dangers

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    Full Text Available ... lens because they can be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, ... Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume Contacts May Contain Chemicals Harmful to Eyes ...

  11. Contact Us about Asbestos

    Science.gov (United States)

    How to contact EPA for more information on asbestos, including state and regional contacts, EPA’s Asbestos Abatement/Management Ombudsman and the Toxic Substances Control Act (TSCA) Assistance Information Service (TSCA Hotline).

  12. Colored Contact Lens Dangers

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    Full Text Available ... like a suction cup." Halloween is a popular time for people to use colored contact lenses to ... wear costume contact lenses for Halloween or any time of year, follow these guidelines: Get an eye ...

  13. Colored Contact Lens Dangers

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    Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... an ophthalmologist — an eye medical doctor — who will measure each eye and talk to you about proper ...

  14. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are considering ... Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at ...

  15. Colored Contact Lens Dangers

    Medline Plus

    Full Text Available ... prescription. Follow the contact lens care directions for cleaning, disinfecting, and wearing the lenses. Never share contact ... with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American ...

  16. Identification of an HLA-A2-restricted CD147 epitope that can induce specific CTL cytotoxicity against drug resistant MCF-7/Adr cells.

    Science.gov (United States)

    Qu, Chuang; Gao, Shuhui; Shao, Hongwei; Zhang, Wenfeng; Bo, Huabben; Lu, Xin; Chen, Tianjiao; Kou, Jing; Wang, Yue; Chen, Gui Si; Huang, Shulin; Shen, Han

    2018-04-01

    Cluster of differentiation (CD)147 is highly expressed in drug-resistant tumor cell lines and is involved in the formation of tumor drug resistance. Therefore, immunotherapy utilizing CD147 epitope peptides is a promising approach for the elimination of drug-resistant tumor cells. However, like most tumor-associated antigens (TAAs), CD147 belongs to the autoantigen category, and T cells that recognize high affinity, immunodominant epitopes from autoantigens are deleted though thymic negative selection. Furthermore, wild-type autoantigen peptides cannot effectively activate and expand T lymphocytes with lower affinity T cell receptors in vivo . However, mutations of TAA peptides have been demonstrated to increase the affinity of major histocompatibility complex molecules and their binding to T cell receptor molecules, leading to activation of T lymphocytes in vitro . In the present study, a high-affinity point mutation peptide, CD147 126-134 L2, was predicted by the human leukocyte antigen (HLA) binding prediction algorithm and its affinity was testified using a T2 binding assay. In addition, when peptide-specific cytotoxic T lymphocytes (CTLs) were stimulated with dendritic cells loaded with the CD147 126-134 L2 peptide under HLA-A*02:01 restriction, interferon-γ release and cytotoxicity assays showed that peptide-specific CTLs effectively cross-recognized and lysed T2 target cells loaded either with the wild-type (CD147 126-134 ) or mutated peptide (CD147 126-134 L2). Moreover, the CD147 126-134 L2 peptide-specific CTLs exerted strong cytotoxic activity against drug-resistant MCF-7/Adr cells, which express a high level of CD147 and are HLA-A*02:01-positive, but not against normal MCF-7 cells. Thus, this suggests that the wild-type peptide (CD147 126-134 ) is naturally presented on HLA-A*02:01 of CD147-expressing MCF-7/Adr cells and is cross-recognized by CTLs. In conclusion, an HLA-A*02:01-restricted CD147-point mutant epitope peptide was identified that induces

  17. Hepatocyte SLAMF3 reduced specifically the multidrugs resistance protein MRP-1 and increases HCC cells sensitization to anti-cancer drugs.

    Science.gov (United States)

    Fouquet, Grégory; Debuysscher, Véronique; Ouled-Haddou, Hakim; Eugenio, Mélanie Simoes; Demey, Baptiste; Singh, Amrathlal Rabbind; Ossart, Christèle; Al Bagami, Mohammed; Regimbeau, Jean-Marc; Nguyen-Khac, Eric; Naassila, Mickael; Marcq, Ingrid; Bouhlal, Hicham

    2016-05-31

    Multidrug resistance MDR proteins (MRPs) are members of the C family of a group of proteins named ATP binding cassette (ABC) transporters. MRPs can transport drugs including anticancer drugs, nucleoside analogs, antimetabolites and tyrosine kinase inhibitors. Drugs used in HCC therapy, such as tyrosine kinase inhibitor sorafenib, are substrates of uptake and/or efflux transporters. Variable expression of MRPs at the plasma membrane of tumor cells may contribute to drug resistance and subsequent clinical response. Recently, we reported that the hepatocyte SLAMF3 expression (Signaling Lymphocytic Activation Molecule Family member 3) was reduced in tumor cells from hepatocellular carcinoma (HCC) compared to its high expression in adjacent tissues. In the present study, we make a strong correlation between induced SLAMF3 overexpression and the specific loss of MRP-1 expression and its functionalities as a drugs resistance transporter. No changes were observed on expression of ABCG2 and MDR. More importantly, we highlight a strong inverse correlation between MRP-1 and SLAMF3 expression in patients with HCC. We propose that the SLAMF3 overexpression in cancerous cells could represent a potential therapeutic strategy to improve the drugs sensibility of resistant cells and thus control the therapeutic failure in HCC patients.

  18. Contact lens in keratoconus

    OpenAIRE

    Rathi, Varsha M; Mandathara, Preeji S; Dumpati, Srikanth

    2013-01-01

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

  19. Global deletion of lipocalin 2 does not reverse high-fat diet-induced obesity resistance in stearoyl-CoA desaturase-1 skin-specific knockout mice.

    Science.gov (United States)

    Friedlander, Nicholas J; Burhans, Maggie S; Ade, Lacmbouh; O'Neill, Lucas M; Chen, Xiaoli; Ntambi, James M

    2014-03-14

    Over the past century, obesity has developed into a paramount health issue that affects millions of people worldwide. Obese individuals have an increased risk to develop other metabolic disorders, such as insulin resistance and atherosclerosis, among others. Previously we determined that mice lacking stearoyl-CoA desaturase-1 (SCD1) enzyme specifically in the skin (SKO) were lean and protected from high-fat diet induced adiposity. Additionally, lipocalin 2 (Lcn2) mRNA was found to be 27-fold higher in the skin of SKO mice compared to control mice. Given reports suggesting that Lcn2 plays a role in protection against diet-induced weight gain, adiposity and insulin resistance, we hypothesized that deletion of Lcn2 alongside the skin-specific SCD1 deficiency would diminish the obesity resistance observed in SKO mice. To test this, we developed mice lacking SCD1 expression in the skin and also lacking Lcn2 expression globally and surprisingly, these mice did not gain significantly more weight than the SKO mice under high-fat diet conditions. Therefore, we conclude that Lcn2 does not mediate the protection against high-fat diet-induced adiposity observed in SKO mice. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Contact radiotherapy. Report of technological assessment

    International Nuclear Information System (INIS)

    Ortholan, Cecile; Melin, Nicole; Lee-Robin, Sun Hae; David, Denis Jean; Pages, Frederique; Devaud, Christine; Noel, Georges; Biga, Julie; Moty-Monnereau, Celine; Canet, Philippe; Lascols, Sylvie; Lamas, Muriel; Ramdine, Jessica; Tuil, Louise

    2008-10-01

    This report aims at assessing safety, indications, the role in therapeutic strategy, and efficiency of contact radiotherapy. It also aims at answering questions like: is the contact radiotherapy technique validated? What are the indications for contact radiotherapy? What about the efficiency and safety of contact radiotherapy? After a presentation of preliminary notions on radiotherapy (radiation types, dose, and irradiation techniques), the report presents this specific technique of contact radiotherapy: definition, devices, use recommendations, issues of radiation protection, modalities of performance of a contact radiotherapy session, and concerned pathologies. Then, based on a literature survey, this report addresses the various concerned tumours (skin, rectum, brain, breast), indicates some general information about these tumours (epidemiological data, anatomy and classification, therapeutic options, radiotherapy), and proposes an assessment of the efficiency and safety of contact radiotherapy