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....

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

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.

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.

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.

Resistance switching in silver - manganite contacts

Energy Technology Data Exchange (ETDEWEB)

Gomez-Marlasca, F [Materia Condensada GIA GAIANN CAC -CNEA, and Instituto de Nanociencia y Nanotecnologia, CNEA, Gral Paz 1499 (1650) San Martin, Pcia. Buenos Aires (Argentina); Levy, P, E-mail: levy@cnea.gov.a

2009-05-01

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.

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.

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

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

Contact resistance at ceramic interfaces and its dependence on mechanical load

DEFF Research Database (Denmark)

Koch, Søren; Hendriksen, P.V.

2004-01-01

Low contact resistance between individual components is important for solid oxide fuel cell stacks if high performance is to be achieved. Several mechanisms may result in high contact resistance, e.g., current constriction due to low area of contact and formation of resistive phases between...... the components. In this study, the importance of current constriction due to limited area of contact at an interface is investigated by comparing the characteristics of contacts between LSM pellets with different surface finish. The load behaviour of the contact resistance has been investigated and a power law...... of the contact resistance was calculated using a simple model describing the variation of the contact area with load based on the measured surface roughness. Good agreement between the calculations and the experimentally observed resistances was found. (C) 2004 Elsevier B.V. All rights reserved....

The role of contact resistance in graphene field-effect devices

Science.gov (United States)

Giubileo, Filippo; Di Bartolomeo, Antonio

2017-08-01

The extremely high carrier mobility and the unique band structure, make graphene very useful for field-effect transistor applications. According to several works, the primary limitation to graphene based transistor performance is not related to the material quality, but to extrinsic factors that affect the electronic transport properties. One of the most important parasitic element is the contact resistance appearing between graphene and the metal electrodes functioning as the source and the drain. Ohmic contacts to graphene, with low contact resistances, are necessary for injection and extraction of majority charge carriers to prevent transistor parameter fluctuations caused by variations of the contact resistance. The International Technology Roadmap for Semiconductors, toward integration and down-scaling of graphene electronic devices, identifies as a challenge the development of a CMOS compatible process that enables reproducible formation of low contact resistance. However, the contact resistance is still not well understood despite it is a crucial barrier towards further improvements. In this paper, we review the experimental and theoretical activity that in the last decade has been focusing on the reduction of the contact resistance in graphene transistors. We will summarize the specific properties of graphene-metal contacts with particular attention to the nature of metals, impact of fabrication process, Fermi level pinning, interface modifications induced through surface processes, charge transport mechanism, and edge contact formation.

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.

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.

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

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

Transfer characteristics and contact resistance in Ni- and Ti-contacted graphene-based field-effect transistors

International Nuclear Information System (INIS)

Di Bartolomeo, A; Giubileo, F; Iemmo, L; Romeo, F; Santandrea, S; Gambardella, U

2013-01-01

We produced graphene-based field-effect transistors by contacting mono- and bi-layer graphene by sputtering Ni or Ti as metal electrodes. We performed electrical characterization of the devices by measuring their transfer and output characteristics. We clearly observed the presence of a double-dip feature in the conductance curve for Ni-contacted transistors, and we explain it in terms of charge transfer and graphene doping under the metal contacts. We also studied the contact resistance between the graphene and the metal electrodes with larger values of ∼30 kΩμm 2 recorded for Ti contacts. Importantly, we prove that the contact resistance is modulated by the back-gate voltage. (paper)

Contact resistance of ceramic interfaces between materials used for solid oxide fuel cell applications

Energy Technology Data Exchange (ETDEWEB)

Koch, S.

2002-01-01

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 (strontium 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. The influence of the mechanical load on the contact resistance was ascribed to an area effect. The contact resistance of the investigated materials was dominated by current constriction at high temperatures. The measured contact resistance was comparable to the resistance calculated on basis of the contact areas found by optical and electron microscopy. At low temperatures, the interface contribution to the contact resistance was dominating. The cobaltite interface could be described by one potential barrier at the contact interface, whereas the manganite interfaces required several consecutive potential barriers to model the observed behaviour. The current-voltage behaviour of the YSZ contact interfaces was only weakly non-linear, and could be described by 22{+-}1 barriers in series. Contact interfaces with sinterable contact layers were also investigated, and the measured contact resistance for these interfaces were more than 10 times less than for the other interfaces. (au)

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....... The influence of the mechanical load on the contact resistance was ascribed to an area effect. The contact resistance of the investigated materials was dominated by current constric-tion at high temperatures. The measured contact resistance was comparable to the resis-tance calculated on basis of the contact...... areas found by optical and electron microscopy. At low temperatures, the interface contribution to the contact resistance was dominating. The cobaltite interface could be described by one potential barrier at the contact interface, whereas the manganite interfaces required several consecutive potential...

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.

Influences of the disease resistance conferred by the individual ...

African Journals Online (AJOL)

To research possible influences of the disease resistance conferred by different trans-resistance genes on the transgenic rice plants in their yields and grain quality, three transgenic rice lines, including two with the resistance genes Pi-d2 and Pi-d3, respectively, for rice blast, and one with the resistance gene Xa21 for rice ...

Instrument for measuring metal-thermoelectric semiconductor contact resistence

International Nuclear Information System (INIS)

Lanxner, M.; Nechmadi, M.; Meiri, B.; Schildkraut, I.

1979-02-01

An instrument for measuring electrical, metal-thermoelectric semiconductor contact resistance is described. The expected errors of measurement are indicated. The operation of the instrument which is based on potential traversing perpendicularly to the contact plane is illustrated for the case of contacts of palladium and bismuth telluride-based thermoelectric material

Testing and Modeling of Contact Problems in Resistance Welding

DEFF Research Database (Denmark)

Song, Quanfeng

together two or three cylindrical parts as well as disc-ring pairs of dissimilar metals. The tests have demonstrated the effectiveness of the model. A theoretical and experimental study is performed on the contact resistance aiming at a more reliable model for numerical simulation of resistance welding......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...... for the formulation, and the interfaces are treated in a symmetric pattern. The frictional sliding contact is also solved employing the constant friction model. The algorithm is incorporated into the finite element code. Verification is carried out in some numerical tests as well as experiments such as upsetting...

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

Characterizations of contact and sheet resistances of vertically aligned carbon nanotube forests with intrinsic bottom contacts

Energy Technology Data Exchange (ETDEWEB)

Jiang Yingqi; Wang Pengbo; Lin Liwei, E-mail: jiangyq99@gmail.com, E-mail: lwlin@me.berkeley.edu [Mechanical Engineering Department, University of California at Berkeley (United States)

2011-09-07

Comprehensive studies on the sheet and contact resistances of vertically aligned carbon nanotube (CNT) forests with as-grown bottom contacts to the metal layer have been conducted. Using microfabrication and four distinct methods: (1) the transfer length method (TLM), (2) the contact chain method, (3) the Kelvin method, and (4) the four point probe method, we have designed multiple testing devices to characterize the resistances of CNT-forest-based devices. Experimental results show that devices based on stripe-shaped CNT forests 100 {mu}m in height and 100 {mu}m in width have a sheet resistance of approximately 100{Omega}/{open_square}. The corresponding specific contact resistance to the molybdenum layer is roughly 5 x 10{sup 4} {Omega} {mu}m{sup 2}. Consistency of the results from the four different methods validates the study. After two months of storage of the CNT forest samples in open air, less than 0.9% deviations in the resistance values were observed. We further demonstrated one application of CNT forests as an NH{sub 3} gas sensor and measured 0.5 ppm of sensing resolution with a detection response time of 1 min.

Low resistivity contacts to YBa2Cu3O(7-x) superconductors

Science.gov (United States)

Hsi, Chi-Shiung; Haertling, Gene H.

1991-01-01

Silver, gold, platinum, and palladium metals were investigated as electroding materials for the YBa2Cu3O(7-x) superconductors. Painting, embedding, and melting techniques were used to apply the electrodes. Contact resistivities were determined by: (1) type of electrode; (2) firing conditions; and (3) application method. Electrodes fired for long times exhibited lower contact resistivities than those fired for short times. Low-resistivity contacts were found for silver and gold electrodes. Silver, which made good ohmic contact to the YBa2Cu3O(7-x) superconductor with low contact resistivities was found to be the best electroding material among the materials evaluated in this investigation.

Bulk and contact resistances of gas diffusion layers in proton exchange membrane fuel cells

Science.gov (United States)

Ye, Donghao; Gauthier, Eric; Benziger, Jay B.; Pan, Mu

2014-06-01

A multi-electrode probe is employed to distinguish the bulk and contact resistances of the catalyst layer (CL) and the gas diffusion layer (GDL) with the bipolar plate (BPP). Resistances are compared for Vulcan carbon catalyst layers (CL), carbon paper and carbon cloth GDL materials, and GDLs with microporous layers (MPL). The Vulcan carbon catalyst layer bulk resistance is 100 times greater than the bulk resistance of carbon paper GDL (Toray TG-H-120). Carbon cloth (CCWP) has bulk and contact resistances twice those of carbon paper. Compression of the GDL decreases the GDL contact resistance, but has little effect on the bulk resistance. Treatment of the GDL with polytetrafluoroethylene (PTFE) increases the contact resistance, but has little effect on the bulk resistance. A microporous layer (MPL) added to the GDL decreases the contact resistance, but has little effect on the bulk resistance. An equivalent circuit model shows that for channels less than 1 mm wide the contact resistance is the major source of electronic resistance and is about 10% of the total ohmic resistance associated with the membrane electrode assembly.

Improvement of Metal-Graphene Ohmic Contact Resistance in Bilayer Epitaxial Graphene Devices

International Nuclear Information System (INIS)

He Ze-Zhao; Yang Ke-Wu; Yu Cui; Li Jia; Liu Qing-Bin; Lu Wei-Li; Feng Zhi-Hong; Cai Shu-Jun

2015-01-01

We report on an improved metal-graphene ohmic contact in bilayer epitaxial graphene on a SiC substrate with contact resistance below 0.1 ω·mm. Monolayer and bilayer epitaxial graphenes are prepared on a 4H-SiC substrate in this work. Their contact resistances are measured by a transfer length method. An improved photoresist-free device fabrication method is used and is compared with the conventional device fabrication method. Compared with the monolayer graphene, the contact resistance R c of bilayer graphene improves from an average of 0.24 ω·mm to 0.1 ω·mm. Ohmic contact formation mechanism analysis by Landauer's approach reveals that the obtained low ohmic contact resistance in bilayer epitaxial graphene is due to their high carrier density, high carrier transmission probability, and p-type doping introduced by contact metal Au. (paper)

Measuring the electrical resistivity and contact resistance of vertical carbon nanotube bundles for application as interconnects

International Nuclear Information System (INIS)

Chiodarelli, Nicolo'; Li, Yunlong; Arstila, Kai; Richard, Olivier; Cott, Daire J; Heyns, Marc; De Gendt, Stefan; Groeseneken, Guido; Vereecken, Philippe M; Masahito, Sugiura; Kashiwagi, Yusaku

2011-01-01

Carbon nanotubes (CNT) are known to be materials with potential for manufacturing sub-20 nm high aspect ratio vertical interconnects in future microchips. In order to be successful with respect to contending against established tungsten or copper based interconnects, though, CNT must fulfil their promise of also providing low electrical resistance in integrated structures using scalable integration processes fully compatible with silicon technology. Hence, carefully engineered growth and integration solutions are required before we can fully exploit their potentialities. This work tackles the problem of optimizing a CNT integration process from the electrical perspective. The technique of measuring the CNT resistance as a function of the CNT length is here extended to CNT integrated in vertical contacts. This allows extracting the linear resistivity and the contact resistance of the CNT, two parameters to our knowledge never reported separately for vertical CNT contacts and which are of utmost importance, as they respectively measure the quality of the CNT and that of their metal contacts. The technique proposed allows electrically distinguishing the impact of each processing step individually on the CNT resistivity and the CNT contact resistance. Hence it constitutes a powerful technique for optimizing the process and developing CNT contacts of superior quality. This can be of relevant technological importance not only for interconnects but also for all those applications that rely on the electrical properties of CNT grown with a catalytic chemical vapor deposition method at low temperature.

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.

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

CoSix contact resistance after etching and ashing plasma exposure

International Nuclear Information System (INIS)

Katahira, Ken; Fukasawa, Masanaga; Kobayashi, Shoji; Takizawa, Toshifumi; Isobe, Michio; Hamaguchi, Satoshi; Nagahata, Kazunori; Tatsumi, Tetsuya

2009-01-01

The authors investigated the contact resistance fluctuation caused by CoSi x damage in plasma etching and ashing processes. They found that CoSi x layers damaged by plasma process exposure are readily oxidized when exposed to air resulting in increased resistance. They also found that the contact resistance increases more when CH 3 F is used instead of CF 4 during etching process. The lower the mass number of dominant ions becomes, the deeper the ions penetrate. Molecular dynamics simulation revealed that dissociated species from lighter ions penetrate deeper and that this stimulates deeper oxidation. They also found that contact resistance further increased by using postetch ashing plasma even in an H 2 /N 2 ashing process in which O 2 was not used. Here, too, the reason for this is that the ion penetration causes deep oxidation. They observed that the contact resistance has a linear relationship with the oxide concentration in CoSi x . This leads to the conclusion that it is essential to precisely control the ion energy as well as to properly select the ion species in the plasma process in the fabrication of next-generation semiconductor devices.

Transgenic strategies to confer resistance against viruses in rice plants

Directory of Open Access Journals (Sweden)

Takahide eSasaya

2014-01-01

Full Text Available Rice (Oryza sativa L. is cultivated in more than 100 countries and supports nearly half of the world’s population. Developing efficient methods to control rice viruses is thus an urgent necessity because viruses cause serious losses in rice yield. Most rice viruses are transmitted by insect vectors, notably planthoppers and leafhoppers. Viruliferous insect vectors can disperse their viruses over relatively long distances, and eradication of the viruses is very difficult once they become widespread. Exploitation of natural genetic sources of resistance is one of the most effective approaches to protect crops from virus infection; however, only a few naturally occurring rice genes confer resistance against rice viruses. In an effort to improve control, many investigators are using genetic engineering of rice plants as a potential strategy to control viral diseases. Using viral genes to confer pathogen-derived resistance against crops is a well-established procedure, and the expression of various viral gene products has proved to be effective in preventing or reducing infection by various plant viruses since the 1990s. RNA-interference (RNAi, also known as RNA silencing, is one of the most efficient methods to confer resistance against plant viruses on their respective crops. In this article, we review the recent progress, mainly conducted by our research group, in transgenic strategies to confer resistance against tenuiviruses and reoviruses in rice plants. Our findings also illustrate that not all RNAi constructs against viral RNAs are equally effective in preventing virus infection and that it is important to identify the viral Achilles’ heel gene to target for RNAi attack when engineering plants.

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.

Quantitative genome re-sequencing defines multiple mutations conferring chloroquine resistance in rodent malaria

Science.gov (United States)

2012-01-01

Background Drug resistance in the malaria parasite Plasmodium falciparum severely compromises the treatment and control of malaria. A knowledge of the critical mutations conferring resistance to particular drugs is important in understanding modes of drug action and mechanisms of resistances. They are required to design better therapies and limit drug resistance. A mutation in the gene (pfcrt) encoding a membrane transporter has been identified as a principal determinant of chloroquine resistance in P. falciparum, but we lack a full account of higher level chloroquine resistance. Furthermore, the determinants of resistance in the other major human malaria parasite, P. vivax, are not known. To address these questions, we investigated the genetic basis of chloroquine resistance in an isogenic lineage of rodent malaria parasite P. chabaudi in which high level resistance to chloroquine has been progressively selected under laboratory conditions. Results Loci containing the critical genes were mapped by Linkage Group Selection, using a genetic cross between the high-level chloroquine-resistant mutant and a genetically distinct sensitive strain. A novel high-resolution quantitative whole-genome re-sequencing approach was used to reveal three regions of selection on chr11, chr03 and chr02 that appear progressively at increasing drug doses on three chromosomes. Whole-genome sequencing of the chloroquine-resistant parent identified just four point mutations in different genes on these chromosomes. Three mutations are located at the foci of the selection valleys and are therefore predicted to confer different levels of chloroquine resistance. The critical mutation conferring the first level of chloroquine resistance is found in aat1, a putative aminoacid transporter. Conclusions Quantitative trait loci conferring selectable phenotypes, such as drug resistance, can be mapped directly using progressive genome-wide linkage group selection. Quantitative genome-wide short

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)

The Effect of Tensile Hysteresis and Contact Resistance on the Performance of Strain-Resistant Elastic-Conductive Webbing

Directory of Open Access Journals (Sweden)

Tien-Wei Shyr

2011-01-01

Full Text Available To use e-textiles as a strain-resistance sensor they need to be both elastic and conductive. Three kinds of elastic-conductive webbings, including flat, tubular, and belt webbings, made of Lycra fiber and carbon coated polyamide fiber, were used in this study. The strain-resistance properties of the webbings were evaluated in stretch-recovery tests and measured within 30% strain. It was found that tensile hysteresis and contact resistance significantly influence the tensile elasticity and the resistance sensitivity of the webbings. The results showed that the webbing structure definitely contributes to the tensile hysteresis and contact resistance. The smaller the friction is among the yarns in the belt webbing, the smaller the tensile hysteresis loss. However the close proximity of the conductive yarns in flat and tubular webbings results in a lower contact resistance.

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.

Calculation of Equivalent Resistance for Ground Wires Twined with Armor Rods in Contact Terminals

Directory of Open Access Journals (Sweden)

Gang Liu

2018-03-01

Full Text Available Ground wire breakage accidents can destroy the stable operation of overhead lines. The excessive temperature increase arising from the contact resistance between the ground wire and armor rod in the contact terminal is one of the main reasons causing the breakage of ground wires. Therefore, it is necessary to calculate the equivalent resistance for ground wires twined with armor rods in contact terminals. According to the actual distribution characteristics of the contact points in the contact terminal, a three-dimensional electromagnetic field simulation model of the contact terminal was established. Based on the model, the current distribution in the contact terminal was obtained. Subsequently, the equivalent resistance of a ground wire twined with the armor rod in the contact terminal was calculated. The effects of the factors influencing the equivalent resistance were also discussed. The corresponding verification experiments were conducted on a real ground wire on a contact terminal. The measurement results of the equivalent resistance for the armor rod segment showed good agreement with the electromagnetic modeling results.

Rugged Low-Resistance Contacts To High-Tc Superconductors

Science.gov (United States)

Caton, Randall; Selim, Raouf; Byvik, Charles E.; Buoncristiani, A. Martin

1992-01-01

Newly developed technique involving use of gold makes possible to fabricate low-resistance contacts with rugged connections to high-Tc superconductors. Gold diffused into specimen of superconducting material by melting gold beads onto surface of specimen, making strong mechanical contacts. Shear strength of gold bead contacts greater than epoxy or silver paste. Practical use in high-current-carrying applications of new high-Tc materials, including superconducting magnets, long-wavelength sensors, electrical ground planes at low temperatures, and efficient transmission of power.

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.

Mutation of environmental mycobacteria to resist silver nanoparticles also confers resistance to a common antibiotic.

Science.gov (United States)

Larimer, Curtis; Islam, Mohammad Shyful; Ojha, Anil; Nettleship, Ian

2014-08-01

Non-tuberculous mycobacteria are a threat to human health, gaining entry to the body through contaminated water systems, where they form persistent biofilms despite extensive attempts at disinfection. Silver is a natural antibacterial agent and in nanoparticle form activity is increased by a high surface area. Silver nanoparticles (AgNPs) have been used as alternative disinfectants in circulating water systems, washing machines and even clothing. However, nanoparticles, like any other antibiotic that has a pervasive durable presence, carry the risk of creating a resistant population. In this study Mycobacterium smegmatis strain mc(2)155 was cultured in AgNP enriched agar such that only a small population survived. Surviving cultures were isolated and re-exposed to AgNPs and AgNO3 and resistance to silver was compared to a negative control. After only a single exposure, mutant M. smegmatis populations were resistant to AgNPs and AgNO3. Further, the silver resistant mutants were exposed to antibiotics to determine if general resistance had been conferred. The minimum inhibitory concentration of isoniazid was four times higher for silver resistant mutants than for strain mc(2)155. However, core resistance was not conferred to other toxic metal ions. The mutants had lower resistance to CuSO4 and ZnSO4 than the mc(2)155 strain.

ERK mutations confer resistance to mitogen-activated protein kinase pathway inhibitors.

Science.gov (United States)

Goetz, Eva M; Ghandi, Mahmoud; Treacy, Daniel J; Wagle, Nikhil; Garraway, Levi A

2014-12-01

The use of targeted therapeutics directed against BRAF(V600)-mutant metastatic melanoma improves progression-free survival in many patients; however, acquired drug resistance remains a major medical challenge. By far, the most common clinical resistance mechanism involves reactivation of the MAPK (RAF/MEK/ERK) pathway by a variety of mechanisms. Thus, targeting ERK itself has emerged as an attractive therapeutic concept, and several ERK inhibitors have entered clinical trials. We sought to preemptively determine mutations in ERK1/2 that confer resistance to either ERK inhibitors or combined RAF/MEK inhibition in BRAF(V600)-mutant melanoma. Using a random mutagenesis screen, we identified multiple point mutations in ERK1 (MAPK3) and ERK2 (MAPK1) that could confer resistance to ERK or RAF/MEK inhibitors. ERK inhibitor-resistant alleles were sensitive to RAF/MEK inhibitors and vice versa, suggesting that the future development of alternating RAF/MEK and ERK inhibitor regimens might help circumvent resistance to these agents. ©2014 American Association for Cancer Research.

Influence factors of the inter-nanowire thermal contact resistance in the stacked nanowires

Science.gov (United States)

Wu, Dongxu; Huang, Congliang; Zhong, Jinxin; Lin, Zizhen

2018-05-01

The inter-nanowire thermal contact resistance is important for tuning the thermal conductivity of a nanocomposite for thermoelectric applications. In this paper, the stacked copper nanowires are applied for studying the thermal contact resistance. The stacked copper nanowires are firstly made by the cold-pressing method, and then the nanowire stacks are treated by sintering treatment. With the effect of the volumetric fraction of nanowires in the stack and the influence of the sintering-temperature on the thermal contact resistance discussed, results show that: The thermal conductivity of the 150-nm copper nanowires can be enlarged almost 2 times with the volumetric fraction increased from 32 to 56% because of the enlarged contact-area and contact number of a copper nanowire. When the sintering temperature increases from 293 to 673 K, the thermal conductivity of the stacked 300-nm nanowires could be enlarged almost 2.5 times by the sintering treatment, because of the improved lattice property of the contact zone. In conclusion, application of a high volumetric fraction or/and a sintering-treatment are effectivity to tune the inter-nanowire thermal contact resistance, and thus to tailor the thermal conductivity of a nanowire network or stack.

Increased resistance of contact lens related bacterial biofilms to antimicrobial activity of soft contact lens care solutions

Science.gov (United States)

Szczotka-Flynn, Loretta B.; Imamura, Yoshifumi; Chandra, Jyotsna; Yu, Changping; Mukherjee, Pranab K.; Pearlman, Eric; Ghannoum, Mahmoud A.

2014-01-01

PURPOSE To determine if clinical and reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus form biofilms on silicone hydrogel contact lenses, and ascertain antimicrobial activities of contact lens care solutions. METHODS Clinical and American Type Culture Collection (ATCC) reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus were incubated with lotrafilcon A lenses under conditions that facilitate biofilm formation. Biofilms were quantified by quantitative culturing (colony forming units, CFUs), and gross morphology and architecture were evaluated using scanning electron microscopy (SEM) and confocal microscopy. Susceptibilities of the planktonic and biofilm growth phases of the bacteria to five common multipurpose contact lens care solutions and one hydrogen peroxide care solution were assessed. RESULTS P. aeruginosa, S. marcescens, and S. aureus reference and clinical strains formed biofilms on lotrafilcon A silicone hydrogel contact lenses, as dense networks of cells arranged in multiple layers with visible extracellular matrix. The biofilms were resistant to commonly used biguanide preserved multipurpose care solutions. P. aeruginosa and S. aureus biofilms were susceptible to a hydrogen peroxide and a polyquaternium preserved care solution, whereas S. marcescens biofilm was resistant to a polyquaternium preserved care solution but susceptible to hydrogen peroxide disinfection. In contrast, the planktonic forms were always susceptible. CONCLUSIONS P. aeruginosa, S. marcescens, and S. aureus form biofilms on lotrafilcon A contact lenses, which in contrast to planktonic cells, are resistant to the antimicrobial activity of several soft contact lens care products. PMID:19654521

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

KAUST Repository

Gupta, Rahul P.; Xiong, K.; White, J. B.; Cho, Kyeongjae; Alshareef, Husam N.; Gnade, B. E.

2010-01-01

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.

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.

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.

Experimental determination of fuel-cladding thermal contact resistance

International Nuclear Information System (INIS)

Maglic, K.; Zivotic, Z.

1968-01-01

Thermal resistance of the UO 2 fuel - Zr-2 cladding was measure by the same experimental apparatus which was used for measuring the thermal conductivity of ceramic fuel. Thermal resistance was measure for a series of heat flux values and the dependence of thermal resistance on the flux is given within in the range from 0.66 W/cm 2 to 13.3 W/cm 2 . The temperature drop on the contact surface was between 39 deg C and 181.7 deg C, proportional to the increase of the heat flux [sr

Controllable Electrical Contact Resistance between Cu and Oriented-Bi2Te3 Film via Interface Tuning.

Science.gov (United States)

Kong, Xixia; Zhu, Wei; Cao, Lili; Peng, Yuncheng; Shen, Shengfei; Deng, Yuan

2017-08-02

The contact resistance between metals and semiconductors has become critical for the design of thin-film thermoelectric devices with their continuous miniaturization. Herein, we report a novel interface tuning method to regulate the contact resistance at the Bi 2 Te 3 -Cu interface, and three Bi 2 Te 3 films with different oriented microstructures are obtained. The lowest contact resistivity (∼10 -7 Ω cm 2 ) is observed between highly (00l) oriented Bi 2 Te 3 and Cu film, nearly an order of magnitude lower than other orientations. This significant decrease of contact resistivity is attributed to the denser film connections, lower lattice misfit, larger effective conducting contact area, and smaller width of the surface depletion region. Meanwhile, our results show that the reduction of contact resistance has little dependence on the interfacial diffusion based on the little change in contact resistivity after the introduction of an effective Ti barrier layer. Our work provides a new idea for the mitigation of contact resistivity in thin-film thermoelectric devices and also gives certain guidance for the size design of the next-level miniaturized devices.

Current voltage characteristics of composite superconductors with high contact resistance

International Nuclear Information System (INIS)

Akhmetov, A.A.; Baev, V.P.

1984-01-01

An experimental study has been made of current-voltage characteristics of composite superconductors with contact resistance between superconducting filaments and normal metal with high electrical conductivity. It is shown that stable resistive states exist in such conductors over a wide range of currents. The presence of resistive states is interpreted in terms of the resistive domain concept. The minimum and maximum currents of resistive states are found to be dependent on the electrical resistance of normal metal and magnetic field. (author)

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.

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

Science.gov (United States)

2009-09-01

mechanically cycled by a piezo - electric transducer (PZT). The resistance through the simulated switch was measured using a four-wire measurement technique...determined that the microwave performance of a closed relay can be modeled as a simple resistor to a first order equivalent [106,108]. The relay resistance is...Therefore, a piezo device capable of precise higher frequency motion was chosen to provide cyclic contact motion. This device needed to be physically small

CoSi{sub x} contact resistance after etching and ashing plasma exposure

Energy Technology Data Exchange (ETDEWEB)

Katahira, Ken; Fukasawa, Masanaga; Kobayashi, Shoji; Takizawa, Toshifumi; Isobe, Michio; Hamaguchi, Satoshi; Nagahata, Kazunori; Tatsumi, Tetsuya [Nagasaki Production Division 1, Sony Semiconductor Kyushu Corporation, 1883-43 Tsukuba-machi, Isahaya-shi, Nagasaki 854-0065 (Japan); Semiconductor Technology Development Division, Semiconductor Business Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Semiconductor Technology Development Division, Semiconductor Business Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan)

2009-07-15

The authors investigated the contact resistance fluctuation caused by CoSi{sub x} damage in plasma etching and ashing processes. They found that CoSi{sub x} layers damaged by plasma process exposure are readily oxidized when exposed to air resulting in increased resistance. They also found that the contact resistance increases more when CH{sub 3}F is used instead of CF{sub 4} during etching process. The lower the mass number of dominant ions becomes, the deeper the ions penetrate. Molecular dynamics simulation revealed that dissociated species from lighter ions penetrate deeper and that this stimulates deeper oxidation. They also found that contact resistance further increased by using postetch ashing plasma even in an H{sub 2}/N{sub 2} ashing process in which O{sub 2} was not used. Here, too, the reason for this is that the ion penetration causes deep oxidation. They observed that the contact resistance has a linear relationship with the oxide concentration in CoSi{sub x}. This leads to the conclusion that it is essential to precisely control the ion energy as well as to properly select the ion species in the plasma process in the fabrication of next-generation semiconductor devices.

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

KAUST Repository

Zhang, Bo; Zheng, Tao; Wang, Qingxiao; Zhu, Yihan; Alshareef, Husam N.; Kim, Moon J.; Gnade, Bruce E.

2016-01-01

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

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

KAUST Repository

Allen, Thomas G.; Bullock, James; Jeangros, Quentin; Samundsett, Christian; Wan, Yimao; Cui, Jie; Hessler-Wyser, Aï cha; De Wolf, Stefaan; Javey, Ali; Cuevas, Andres

2017-01-01

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.

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.

Major QTL Conferring Resistance to Rice Bacterial Leaf Streak

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

Bacterial leaf streak (BLS) is one of the important limiting factors to rice production in southern China and other tropical and sub-tropical areas in Asia. Resistance to BLS was found to be a quantitative trait and no major resistant gene was located in rice until date. In the present study, a new major quantitative trait locus (QTL) conferring resistance to BLS was identified from a highly resistant variety Dular by the employment of Dular/Balilla (DB) and Dular/IR24 (DI) segregation populations and was designated qBLSR-11-1. This QTL was located between the simple sequence repeat (SSR) markers RM120 and RM441 on chromosome 11 and could account for 18.1-21.7% and 36.3% of the variance in DB and DI populations, respectively. The genetic pattern of rice resistance to BLS was discussed.

Simplistic graphene transfer process and its impact on contact resistance

KAUST Repository

Ghoneim, Mohamed T.; Smith, Casey; Hussain, Muhammad Mustafa

2013-01-01

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.

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.

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

A novel gene of Kalanchoe daigremontiana confers plant drought resistance.

Science.gov (United States)

Wang, Li; Zhu, Chen; Jin, Lin; Xiao, Aihua; Duan, Jie; Ma, Luyi

2018-02-07

Kalanchoe (K.) daigremontiana is important for studying asexual reproduction under different environmental conditions. Here, we describe a novel KdNOVEL41 (KdN41) gene that may confer drought resistance and could thereby affect K. daigremontiana development. The detected subcellular localization of a KdN41/Yellow Fluorescent Protein (YFP) fusion protein was in the nucleus and cell membrane. Drought, salt, and heat stress treatment in tobacco plants containing the KdN41 gene promoter driving β-glucuronidase (GUS) gene transcription revealed that only drought stress triggered strong GUS staining in the vascular tissues. Overexpression (OE) of the KdN41 gene conferred improved drought resistance in tobacco plants compared to wild-type and transformed with empty vector plants by inducing higher antioxidant enzyme activities, decreasing cell membrane damage, increasing abscisic acid (ABA) content, causing reinforced drought resistance related gene expression profiles. The 3,3'-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining results also showed less relative oxygen species (ROS) content in KdN41-overexpressing tobacco leaf during drought stress. Surprisingly, by re-watering after drought stress, KdN41-overexpressing tobacco showed earlier flowering. Overall, the KdN41 gene plays roles in ROS scavenging and osmotic damage reduction to improve tobacco drought resistance, which may increase our understanding of the molecular network involved in developmental manipulation under drought stress in K. daigremontiana.

Thermal contact resistance of a particle on a substrate

International Nuclear Information System (INIS)

Tan, J.; Safa, H.; Bonin, B.

1996-01-01

It has been formerly established that field emission in RF cavities is mainly due to contamination by small micron size particles lying on the surface. When applying the RF field, these particles can melt and stick to the surface making it harder to get rid of them. In order to understand the thermal process involved, a crucial physical quantity is needed: the thermal contact resistance between the particle and the substrate. An experimental method is described to measure this quantity, with the use of a scanning electron microscope. By defocusing the beam of the SEM, one can get enough power deposited in one particle to melt it. The power level at which the particle melts gives the thermal contact resistance. Therefore, using the measured value, thermal calculations yield some hints for understanding the violent thermal processes observed in RF fields. (author)

A horizontally gene transferred copper resistance locus confers hyper‐resistance to antibacterial copper toxicity and enables survival of community acquired methicillin resistant Staphylococcus aureus USA300 in macrophages

Science.gov (United States)

Purves, Joanne; Thomas, Jamie; Riboldi, Gustavo P.; Zapotoczna, Marta; Tarrant, Emma; Andrew, Peter W.; Londoño, Alejandra; Planet, Paul J.; Geoghegan, Joan A.; Waldron, Kevin J.

2018-01-01

Summary Excess copper is highly toxic and forms part of the host innate immune system's antibacterial arsenal, accumulating at sites of infection and acting within macrophages to kill engulfed pathogens. We show for the first time that a novel, horizontally gene transferred copper resistance locus (copXL), uniquely associated with the SCCmec elements of the highly virulent, epidemic, community acquired methicillin resistant Staphylococcus aureus (CA‐MRSA) USA300, confers copper hyper‐resistance. These genes are additional to existing core genome copper resistance mechanisms, and are not found in typical S. aureus lineages, but are increasingly identified in emerging pathogenic isolates. Our data show that CopX, a putative P1B‐3‐ATPase efflux transporter, and CopL, a novel lipoprotein, confer copper hyper‐resistance compared to typical S. aureus strains. The copXL genes form an operon that is tightly repressed in low copper environments by the copper regulator CsoR. Significantly, CopX and CopL are important for S. aureus USA300 intracellular survival within macrophages. Therefore, the emergence of new S. aureus clones with the copXL locus has significant implications for public health because these genes confer increased resistance to antibacterial copper toxicity, enhancing bacterial fitness by altering S. aureus interaction with innate immunity. PMID:29521441

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).

Effects of contact resistance on electrical conductivity measurements of SiC-based materials

Energy Technology Data Exchange (ETDEWEB)

Youngblood, G.E.; Thomsen, E.C.; Henager, C.H., E-mail: chuck.henager@pnnl.gov

2013-11-15

A combination 2/4-probe method was used to measure electrical resistances across a pure, monolithic CVD-SiC disc sample with contact resistance at the SiC/metallic electrode interfaces. By comparison of the almost simultaneous 2/4-probe measurements, the specific contact resistance (R{sub c}) and its temperature dependence were determined for two types (sputtered gold and porous nickel) electrodes from room temperature (RT) to ∼973 K. The R{sub c}-values behaved similarly for each type of metallic electrode: R{sub c} > ∼1000 Ω cm{sup 2} at RT, decreasing continuously to ∼1–10 Ω cm{sup 2} at 973 K. The temperature dependence of the inverse R{sub c} indicated thermally activated electrical conduction across the SiC/metallic interface with an apparent activation energy of ∼0.3 eV. For the flow channel insert application in a fusion reactor blanket, contact resistance potentially could reduce the transverse electrical conductivity by about 50%.

A micro-scale model for predicting contact resistance between bipolar plate and gas diffusion layer in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Zhou, Y.; Lin, G.; Shih, A.J.; Hu, S.J. [Department of Mechanical Engineering, The University of Michigan, Ann Arbor, MI 48109-2125 (United States)

2007-01-01

Contact resistance between the bipolar plate (BPP) and the gas diffusion layer (GDL) in a proton exchange membrane (PEM) fuel cell constitutes a significant portion of the overall fuel cell electrical resistance under the normal operation conditions. Most current methods for contact resistance estimation are experimental and there is a lack of well developed theoretical methods. A micro-scale numerical model is developed to predict the electrical contact resistance between BPP and GDL by simulating the BPP surface topology and GDL structure and numerically determining the status for each contact spot. The total resistance and pressure are obtained by considering all contact spots as resistances in parallel and summing the results together. This model shows good agreements with experimental results. Influences of BPP surface roughness parameters on contact resistance are also studied. This model is beneficial in understanding the contact behavior between BPP and GDL and can be integrated with other fuel cell simulations to predict the overall performance of PEM fuel cells. (author)

Mathematical Modeling of Contact Resistance in Silicon Photovoltaic Cells

KAUST Repository

Black, J. P.; Breward, C. J. W.; Howell, P. D.; Young, R. J. S.

2013-01-01

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

Contact Resistance Reduction of ZnO Thin Film Transistors (TFTs) with Saw-Shaped Electrode

KAUST Repository

Park, Woojin

2018-05-15

We report a saw-shaped electrode architecture ZnO thin film transistor (TFT) for effectively increase channel width. Such a saw-shaped electrode has ~2 times longer contact line at the contact metal/ZnO channel junction. We experimentally observed an enhancement in the output drive current by 50% and reduction in the contact resistance by over 50%, when compared to a typical shaped electrode ZnO TFT consuming the same chip area. This performance enhancement is attributed to extension of channel width. This technique can contribute to device performance enhancement and especially reduction in the contact resistance which is a serious challenge.

Microscopic mapping of specific contact resistances and long-term reliability tests on 4H-silicon carbide using sputtered titanium tungsten contacts for high temperature device applications

Science.gov (United States)

Lee, S.-K.; Zetterling, C.-M.; Ostling, M.

2002-07-01

We report on the microscopic mapping of specific contact resistances (rhoc) and long-term reliability tests using sputtered titanium tungsten (TiW) ohmic contacts to highly doped n-type epilayers of 4H-silicon carbide. The TiW ohmic contacts showed good uniformity with low contact resistivity of 3.3 x10-5 Omega cm2. Microscopic mapping of the rhoc showed that the rhoc had a distribution that decreased from the center to the edge of the wafer. This distribution of the rhoc is caused by variation of the doping concentration of the wafer. Sacrificial oxidation at high temperature partially recovered inductively coupled plasma etch damage. TiW contacts with platinum and gold capping layers have stable specific contact resistance at 500 and 600 degC in a vacuum chamber for 308 h.

Photothermal radiometry applied to characterization and control of thermal contact resistance of crimped metals; Radiometrie photothermique appliquee a la caracterisation et au controle de la resistance thermique de contact de metaux sertis

Energy Technology Data Exchange (ETDEWEB)

Van Schel, Etienne

1989-11-15

Modulated photothermal radiometry is used to study the thermal contact between two metals. At first, two models using a bidimensional axisymmetric geometry are proposed to describe the interface: the first one deals with thermal contact resistance, the second one with an equivalent layer. A thorough calculation of the photothermal signal taking into account the nature of the sample and the detection is here presented. Theoretical simulations show the influence of several parameters (frequency. dimensions of the excitation and the detection) on the sensitivity of the method applied to the detection of the thermal resistance. The comparison, with a three layer-model justifies the use of thermal resistance in periodical regime, for air layers between metals. Then, we present an experimental device that is used to validate the model. The results, obtained on duralumin-copper samples, show the sensitivity of the method and lead us to propose values of thermal contact resistance for different crimpings. At last an industrial testing equipment is described. The results, obtained on laboratory samples, are confirmed. Heat exchanger pipes, including voluntary defects are tested. Thanks to this device, we are able to make an in situ crimping control that can also be applied to other types of contacts. [French] La radiometrie photothermique est utilisee pour etudier le contact thermique entre deux metaux. Tout d'abord, deux modeles utilisant une geometrie bidimensionnelle axisymetrique sont proposes pour decrire l'interface: le premier utilise une resistance thermique de contact, le second un milieu equivalent Un calcul complet du signal photothermique, prenant en compte la nature de l'echantillon et de la detection, est presente. Des simulations theoriques montrent l'influence de quelques parametres (frequence, dimensions de l'excitation et de la detection) sur la sensibilite de la methode a la detection de la resistance thermique. La comparaison, avec un modele a trois

Contact Modelling in Resistance Welding, Part II: Experimental Validation

DEFF Research Database (Denmark)

Song, Quanfeng; Zhang, Wenqi; Bay, Niels

2006-01-01

Contact algorithms in resistance welding presented in the previous paper are experimentally validated in the present paper. In order to verify the mechanical contact algorithm, two types of experiments, i.e. sandwich upsetting of circular, cylindrical specimens and compression tests of discs...... with a solid ring projection towards a flat ring, are carried out at room temperature. The complete algorithm, involving not only the mechanical model but also the thermal and electrical models, is validated by projection welding experiments. The experimental results are in satisfactory agreement...

Thermal contact resistance of a particle on a substrate

International Nuclear Information System (INIS)

Tan, J.; Safa, H.; Bonin, B.

1996-01-01

It has been formerly established that field emission in RF cavities is mainly die to contamination by small micron size particles lying on the surface. When applying the RF field, these particles can melt and stick to the surface making it harder to get rid of them. In order to understand the thermal process involved, a crucial physical quantity is needed: the thermal contact resistance between the particle and the substrate. In the present paper, an experimental method is described to measure this quantity, with the use of a scanning electron microscope. By defocusing the beam of the SEM, one can get enough power deposited in one particle to melt it. The power level at which the particle melts gives the thermal contact resistance. Therefore, using the measured value, thermal calculations yield some hints for understanding the violent thermal processes observed in RF fields. (author)

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

Food supply confers calcifiers resistance to ocean acidification

KAUST Repository

Ramajo, Laura; Pé rez-Leó n, Elia; Hendriks, Iris E.; Marbà , Nú ria; Krause-Jensen, Dorte; Sejr, Mikael K.; Blicher, Martin E.; Lagos, Nelson A.; Olsen, Ylva S.; Duarte, Carlos M.

2016-01-01

Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.

Food supply confers calcifiers resistance to ocean acidification

KAUST Repository

Ramajo, Laura

2016-01-18

Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.

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

mTOR Signaling Confers Resistance to Targeted Cancer Drugs.

Science.gov (United States)

Guri, Yakir; Hall, Michael N

2016-11-01

Cancer is a complex disease and a leading cause of death worldwide. Extensive research over decades has led to the development of therapies that target cancer-specific signaling pathways. However, the clinical benefits of such drugs are at best transient due to tumors displaying intrinsic or adaptive resistance. The underlying compensatory pathways that allow cancer cells to circumvent a drug blockade are poorly understood. We review here recent studies suggesting that mammalian TOR (mTOR) signaling is a major compensatory pathway conferring resistance to many cancer drugs. mTOR-mediated resistance can be cell-autonomous or non-cell-autonomous. These findings suggest that mTOR signaling should be monitored routinely in tumors and that an mTOR inhibitor should be considered as a co-therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

Evaluation of Blast Resistance of Fiber Reinforced Composite Specimens under Contact Blast Load

Science.gov (United States)

Janota, O.; Foglar, M.

2017-09-01

This paper presents results of experimental programme which took place in 2014, 2015 and 2016. Experiments were focused on the resistance of full scale concrete panels subjected to contact blast loading. Specimens were loaded by contact blast by plastic explosive. All specimens were reinforced concrete slabs made of fiber concrete. Basalt mesh and textile sheets were added to some of the experiments for creating more heterogeneous material to achieve better resistance of the specimens. Evaluation of experiments was mainly focused on the damaged area on the contact side and soffit of the specimens. Dependency of the final damage of concrete panels on the weight of explosive and concrete strength was assessed.

Mutations in the Plasmodium falciparum Cyclic Amine Resistance Locus (PfCARL Confer Multidrug Resistance

Directory of Open Access Journals (Sweden)

Gregory LaMonte

2016-07-01

Full Text Available Mutations in the Plasmodium falciparum cyclic amine resistance locus (PfCARL are associated with parasite resistance to the imidazolopiperazines, a potent class of novel antimalarial compounds that display both prophylactic and transmission-blocking activity, in addition to activity against blood-stage parasites. Here, we show that pfcarl encodes a protein, with a predicted molecular weight of 153 kDa, that localizes to the cis-Golgi apparatus of the parasite in both asexual and sexual blood stages. Utilizing clustered regularly interspaced short palindromic repeat (CRISPR-mediated gene introduction of 5 variants (L830V, S1076N/I, V1103L, and I1139K, we demonstrate that mutations in pfcarl are sufficient to generate resistance against the imidazolopiperazines in both asexual and sexual blood-stage parasites. We further determined that the mutant PfCARL protein confers resistance to several structurally unrelated compounds. These data suggest that PfCARL modulates the levels of small-molecule inhibitors that affect Golgi-related processes, such as protein sorting or membrane trafficking, and is therefore an important mechanism of resistance in malaria parasites.

A mechanical-electrical finite element method model for predicting contact resistance between bipolar plate and gas diffusion layer in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Lai, Xinmin; Liu, Dong' an; Peng, Linfa [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Ni, Jun [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125 (United States)

2008-07-15

Contact resistance between the bipolar plate (BPP) and the gas diffusion layer (GDL) plays a significant role on the power loss in a proton exchange membrane (PEM) fuel cell. There are two types of contact behavior at the interface of the BPP and GDL, which are the mechanical one and the electrical one. Furthermore, the electrical contact behavior is dependent on the mechanical one. Thus, prediction of the contact resistance is a coupled mechanical-electrical problem. The current FEM models for contact resistance estimation can only simulate the mechanical contact behavior and moreover they are based on the assumption that the contact surface is equipotential, which is not the case in a real BPP/GDL assembly due to the round corner and margin of the BPP. In this study, a mechanical-electrical FEM model was developed to predict the contact resistance between the BPP and GDL based on the experimental interfacial contact resistivity. At first, the interfacial contact resistivity was obtained by experimentally measuring the contact resistance between the GDL and a flat graphite plate of the same material and processing conditions as the BPP. Then, with the interfacial contact resistivity, the mechanical and electrical contact behaviors were defined and the potential distribution of the BPP/GDL assembly was analyzed using the mechanical-electrical FEM model. At last, the contact resistance was calculated according to the potential drop and the current of the contact surface. The numerical results were validated by comparing with those of the model reported previously. The influence of the round corner of the BPP on the contact resistance was also studied and it is found that there exists an optimal round corner that can minimize the contact resistance. This model is beneficial in understanding the mechanical and electrical contact behaviors between the BPP and GDL, and can be used to predict the contact resistance in a new BPP/GDL assembly. (author)

Resistance of Pseudomonas aeruginosa isolates to hydrogel contact lens disinfection correlates with cytotoxic activity.

Science.gov (United States)

Lakkis, C; Fleiszig, S M

2001-04-01

One of the most common pathogens in infection of hydrogel contact lens wearers is Pseudomonas aeruginosa, which can gain access to the eye via contamination of the lens, lens case, and lens care solutions. Only one strain per species is used in current regulatory testing for the marketing of chemical contact lens disinfectants. The aim of this study was to determine whether P. aeruginosa strains vary in their susceptibility to hydrogel contact lens disinfectants. A method for rapidly screening bacterial susceptibility to contact lens disinfectants was developed, based on measurement of the MIC. The susceptibility of 35 P. aeruginosa isolates to two chemical disinfectants was found to vary among strains. MICs ranged from 6.25 to 100% for both disinfectants at 37 degrees C, and a number of strains were not inhibited by a 100% disinfectant concentration in the lens case environment at room temperature (22 degrees C). Resistance to disinfection appeared to be an inherent rather than acquired trait, since some resistant strains had been isolated prior to the introduction of the disinfectants and some susceptible P. aeruginosa strains could not be made more resistant by repeated disinfectant exposure. A number of P. aeruginosa strains which were comparatively more resistant to short-term disinfectant exposure also demonstrated the ability to grow to levels above the initial inoculum in one chemical disinfectant after long-term (24 to 48 h) disinfectant exposure. Resistance was correlated with acute cytotoxic activity toward corneal epithelial cells and with exsA, which encodes a protein that regulates cytotoxicity via a complex type III secretion system. These results suggest that chemical disinfection solutions may select for contamination with cytotoxic strains. Further investigation of the mechanisms and factors responsible for resistance may also lead to strategies for reducing adverse responses to contact lens wear.

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

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...

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

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...

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

KAUST Repository

Zhang, Bo; Zheng, Tao; Wang, Qingxiao; Guo, Zaibing; Kim, Moon J.; Alshareef, Husam N.; Gnade, Bruce E.

2018-01-01

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

Multiple origins of resistance-conferring mutations in Plasmodium vivax dihydrofolate reductase

Directory of Open Access Journals (Sweden)

O'Neil Michael T

2008-04-01

Full Text Available Abstract Background In order to maximize the useful therapeutic life of antimalarial drugs, it is crucial to understand the mechanisms by which parasites resistant to antimalarial drugs are selected and spread in natural populations. Recent work has demonstrated that pyrimethamine-resistance conferring mutations in Plasmodium falciparum dihydrofolate reductase (dhfr have arisen rarely de novo, but spread widely in Asia and Africa. The origin and spread of mutations in Plasmodium vivax dhfr were assessed by constructing haplotypes based on sequencing dhfr and its flanking regions. Methods The P. vivax dhfr coding region, 792 bp upstream and 683 bp downstream were amplified and sequenced from 137 contemporary patient isolates from Colombia, India, Indonesia, Papua New Guinea, Sri Lanka, Thailand, and Vanuatu. A repeat motif located 2.6 kb upstream of dhfr was also sequenced from 75 of 137 patient isolates, and mutational relationships among the haplotypes were visualized using the programme Network. Results Synonymous and non-synonymous single nucleotide polymorphisms (SNPs within the dhfr coding region were identified, as was the well-documented in-frame insertion/deletion (indel. SNPs were also identified upstream and downstream of dhfr, with an indel and a highly polymorphic repeat region identified upstream of dhfr. The regions flanking dhfr were highly variable. The double mutant (58R/117N dhfr allele has evolved from several origins, because the 58R is encoded by at least 3 different codons. The triple (58R/61M/117T and quadruple (57L/61M/117T/173F, 57I/58R/61M/117T and 57L/58R/61M/117T mutant alleles had at least three independent origins in Thailand, Indonesia, and Papua New Guinea/Vanuatu. Conclusion It was found that the P. vivax dhfr coding region and its flanking intergenic regions are highly polymorphic and that mutations in P. vivax dhfr that confer antifolate resistance have arisen several times in the Asian region. This contrasts

Two-point concrete resistivity measurements: interfacial phenomena at the electrode–concrete contact zone

International Nuclear Information System (INIS)

McCarter, W J; Taha, H M; Suryanto, B; Starrs, G

2015-01-01

Ac impedance spectroscopy measurements are used to critically examine the end-to-end (two-point) testing technique employed in evaluating the bulk electrical resistivity of concrete. In particular, this paper focusses on the interfacial contact region between the electrode and specimen and the influence of contacting medium and measurement frequency on the impedance response. Two-point and four-point electrode configurations were compared and modelling of the impedance response was undertaken to identify and quantify the contribution of the electrode–specimen contact region on the measured impedance. Measurements are presented in both Bode and Nyquist formats to aid interpretation. Concretes mixes conforming to BSEN206-1 and BS8500-1 were investigated which included concretes containing the supplementary cementitious materials fly ash and ground granulated blast-furnace slag. A measurement protocol is presented for the end-to-end technique in terms of test frequency and electrode–specimen contacting medium in order to minimize electrode–specimen interfacial effect and ensure correct measurement of bulk resistivity. (paper)

A gene encoding maize caffeoyl-CoA O-methyltransferase confers quantitative resistance to multiple pathogens.

Science.gov (United States)

Yang, Qin; He, Yijian; Kabahuma, Mercy; Chaya, Timothy; Kelly, Amy; Borrego, Eli; Bian, Yang; El Kasmi, Farid; Yang, Li; Teixeira, Paulo; Kolkman, Judith; Nelson, Rebecca; Kolomiets, Michael; L Dangl, Jeffery; Wisser, Randall; Caplan, Jeffrey; Li, Xu; Lauter, Nick; Balint-Kurti, Peter

2017-09-01

Alleles that confer multiple disease resistance (MDR) are valuable in crop improvement, although the molecular mechanisms underlying their functions remain largely unknown. A quantitative trait locus, qMdr 9.02 , associated with resistance to three important foliar maize diseases-southern leaf blight, gray leaf spot and northern leaf blight-has been identified on maize chromosome 9. Through fine-mapping, association analysis, expression analysis, insertional mutagenesis and transgenic validation, we demonstrate that ZmCCoAOMT2, which encodes a caffeoyl-CoA O-methyltransferase associated with the phenylpropanoid pathway and lignin production, is the gene within qMdr 9.02 conferring quantitative resistance to both southern leaf blight and gray leaf spot. We suggest that resistance might be caused by allelic variation at the level of both gene expression and amino acid sequence, thus resulting in differences in levels of lignin and other metabolites of the phenylpropanoid pathway and regulation of programmed cell death.

Resistance to Downy Mildew in Lettuce 'La Brillante' is Conferred by Dm50 Gene and Multiple QTL.

Science.gov (United States)

Simko, Ivan; Ochoa, Oswaldo E; Pel, Mathieu A; Tsuchida, Cayla; Font I Forcada, Carolina; Hayes, Ryan J; Truco, Maria-Jose; Antonise, Rudie; Galeano, Carlos H; Michelmore, Richard W

2015-09-01

Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar 'La Brillante' has a high level of field resistance to the disease in California. Testing of a mapping population developed from a cross between 'Salinas 88' and La Brillante in multiple field and laboratory experiments revealed that at least five loci conferred resistance in La Brillante. The presence of a new dominant resistance gene (designated Dm50) that confers complete resistance to specific isolates was detected in laboratory tests of seedlings inoculated with multiple diverse isolates. Dm50 is located in the major resistance cluster on linkage group 2 that contains at least eight major, dominant Dm genes conferring resistance to downy mildew. However, this Dm gene is ineffective against the isolates of B. lactucae prevalent in the field in California and the Netherlands. A quantitative trait locus (QTL) located at the Dm50 chromosomal region (qDM2.2) was detected, though, when the amount of disease was evaluated a month before plants reached harvest maturity. Four additional QTL for resistance to B. lactucae were identified on linkage groups 4 (qDM4.1 and qDM4.2), 7 (qDM7.1), and 9 (qDM9.2). The largest effect was associated with qDM7.1 (up to 32.9% of the total phenotypic variance) that determined resistance in multiple field experiments. Markers identified in the present study will facilitate introduction of these resistance loci into commercial cultivars of lettuce.

Defining the structural requirements for a helix in 23 S ribosomal RNA that confers erythromycin resistance

DEFF Research Database (Denmark)

Douthwaite, S; Powers, T; Lee, J Y

1989-01-01

The helix spanning nucleotides 1198 to 1247 (helix 1200-1250) in Escherichia coli 23 S ribosomal RNA (rRNA) is functionally important in protein synthesis, and deletions in this region confer erythromycin resistance. In order to define the structural requirements for resistance, we have dissected...... deletion mutants show a sensitive phenotype. Deletions that extend into the base-pairing between GCC1208 and GGU1240 result in non-functional 23 S RNAs, which consequently do not confer resistance. A number of phylogenetically conserved nucleotides have been shown to be non-essential for 23 S RNA function....... However, removal of either these or non-conserved nucleotides from helix 1200-1250 measurably reduces the efficiency of 23 S RNA in forming functional ribosomes. We have used chemical probing and a modified primer extension method to investigate erythromycin binding to wild-type and resistant ribosomes...

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.

Surface potential measurement on contact resistance of amorphous-InGaZnO thin film transistors by Kelvin probe force microscopy

Science.gov (United States)

Han, Zhiheng; Xu, Guangwei; Wang, Wei; Lu, Congyan; Lu, Nianduan; Ji, Zhuoyu; Li, Ling; Liu, Ming

2016-07-01

Contact resistance plays an important role in amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). In this paper, the surface potential distributions along the channel have been measured by using Kelvin probe force microscopy (KPFM) on operating a-IGZO TFTs, and sharp potential drops at the edges of source and drain were observed. The source and drain contact resistances can be extracted by dividing sharp potential drops with the corresponding drain to source current. It is found that the contact resistances could not be neglected compared with the whole channel resistances in the a-IGZO TFT, and the contact resistances decrease remarkably with increasing gate biased voltage. Our results suggest that the contact resistances can be controlled by tuning the gate biased voltage. Moreover, a transition from gradual channel approximation to space charge region was observed through the surface potential map directly when TFT operating from linear regime to saturation regime.

Low resistance and transparent Ag/AZO ohmic contact to p-GaN

International Nuclear Information System (INIS)

Han, T.; Wang, T.; Gan, X. W.; Wu, H.; Shi, Y.; Liu, C.

2014-01-01

Silver (Ag)/ aluminum-doped zinc oxide (AZO) films were deposited on p-GaN by using electron beam evaporation. After the annealing process, current -voltage (I-V) measurements were carried out to determine the characteristic of the contacts. The Ag/AZO films annealed at 600 .deg. C were found to present an ohmic contact behavior. The specific contact resistance was calculated to be 9.76 x 10 -4 Ωcm 2 and the transmittance was over 80% for visibly light. The atomic force microscope was used to measure the aggregation of Ag grains which may have been the main factor in the formation of the Ag/AZO ohmic contact to p-GaN.

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.

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

KAUST Repository

Wondmagegn, Wudyalew T.; Satyala, Nikhil T.; Pieper, Ron J.; Quevedo-Ló pez, Manuel Angel Quevedo; Gowrisanker, Srinivas; Alshareef, Husam N.; Stiegler, Harvey J.; Gnade, Bruce E.

2010-01-01

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.

An analytical model and parametric study of electrical contact resistance in proton exchange membrane fuel cells

Energy Technology Data Exchange (ETDEWEB)

Wu, Zhiliang; Wang, Shuxin; Zhang, Lianhong [School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China); Hu, S. Jack [Department of Mechanical Engineering, The University of Michigan, Ann Arbor, MI 48109-2125 (United States)

2009-04-15

This paper presents an analytical model of the electrical contact resistance between the carbon paper gas diffusion layers (GDLs) and the graphite bipolar plates (BPPs) in a proton exchange membrane (PEM) fuel cell. The model is developed based on the classical statistical contact theory for a PEM fuel cell, using the same probability distributions of the GDL structure and BPP surface profile as previously described in Wu et al. [Z. Wu, Y. Zhou, G. Lin, S. Wang, S.J. Hu, J. Power Sources 182 (2008) 265-269] and Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Results show that estimates of the contact resistance compare favorably with experimental data by Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Factors affecting the contact behavior are systematically studied using the analytical model, including the material properties of the two contact bodies and factors arising from the manufacturing processes. The transverse Young's modulus of chopped carbon fibers in the GDL and the surface profile of the BPP are found to be significant to the contact resistance. The factor study also sheds light on the manufacturing requirements of carbon fiber GDLs for a better contact performance in PEM fuel cells. (author)

Development and applications of the contact electric resistance technique

Energy Technology Data Exchange (ETDEWEB)

Saario, T.

1995-12-31

At the moment both the scientific understanding of corrosion processes and the engineering practices of corrosion control in power plants can benefit considerably from the development of in situ on-line instruments for characterisation of the surface films on construction materials. In this work a new in situ Contact Electric Resistance (CER) technique has been developed for measurement of electric resistance of surface films on metals. The CER technique was applied in this work in several different research areas. These include e.g. localized corrosion of stainless steel in paper mill wet end environment, investigation of the effect of inhibitors in steam generator crevice environments, passivation of GaAs single crystals by sulphate treatment and monitoring of the kinetics of oxide growth on zirconium metals in high temperature water. The CER technique has a measurement capacity ranging from 10-9 {omega} to 105 {omega}. The lowest range of resistance is typical for metallic layers deposited on the surface in electrodeposition processes. The highest range of resistance is found for insulator type of films e.g. on zirconium metals. (author)

Protein resistance of surfaces modified with oligo(ethylene glycol) aryl diazonium derivatives.

Science.gov (United States)

Fairman, Callie; Ginges, Joshua Z; Lowe, Stuart B; Gooding, J Justin

2013-07-22

Anti-fouling surfaces are of great importance for reducing background interference in biosensor signals. Oligo(ethylene glycol) (OEG) moieties are commonly used to confer protein resistance on gold, silicon and carbon surfaces. Herein, we report the modification of surfaces using electrochemical deposition of OEG aryl diazonium salts. Using electrochemical and contact angle measurements, the ligand packing density is found to be loose, which supports the findings of the fluorescent protein labelling that aryl diazonium OEGs confer resistance to nonspecific adsorption of proteins albeit lower than alkane thiol-terminated OEGs. In addition to protein resistance, aryl diazonium attachment chemistry results in stable modification. In common with OEG species on gold electrodes, OEGs with distal hydroxyl moieties do confer superior protein resistance to those with a distal methoxy group. This is especially the case for longer derivatives where superior coiling of the OEG chains is possible. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An improved model for predicting electrical contact resistance between bipolar plate and gas diffusion layer in proton exchange membrane fuel cells

Energy Technology Data Exchange (ETDEWEB)

Wu, Zhiliang; Wang, Shuxin [School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China); Zhou, Yuanyuan; Lin, Guosong; Hu, S. Jack [Department of Mechanical Engineering, The University of Michigan, Ann Arbor, MI 48109-2125 (United States)

2008-07-15

Electrical contact resistance between bipolar plates (BPPs) and gas diffusion layers (GDLs) in PEM fuel cells has attracted much attention since it is one significant part of the total contact resistance which plays an important role in fuel cell performance. This paper extends a previous model by Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783] on the prediction of electrical contact resistance within PEM fuel cells. The original microscale numerical model was based on the Hertz solution for individual elastic contacts, assuming that contact bodies, GDL carbon fibers and BPP asperities are isotropic elastic half-spaces. The new model features a more practical contact by taking into account the bending behavior of carbon fibers as well as their anisotropic properties. The microscale single contact process is solved numerically using the finite element method (FEM). The relationship between the contact pressure and the electrical resistance at the GDL/BPP interface is derived by multiple regression models. Comparisons of the original model by Zhou et al. and the new model with experimental data show that the original model slightly overestimates the electrical contact resistance, whereas a better agreement with experimental data is observed using the new model. (author)

The Achievement of Near-Theoretical-Minimum Contact Resistance to InP

Science.gov (United States)

Fatemi, Navid S.; Weizer, Victor G.

1993-01-01

We have investigated the electrical and metallurgical behavior of the InP/Au/Ni contact system. We show that when a layer of Au, 100 A or more in thickness, is introduced between n-InP and Ni contact metallization, specific contact resistivity R, values in the low 10(exp -8) Omega cm(exp 2) range are achieved after sintering. It is suggested that these ultralow values of R(sub c) are due to the presence, at the metal-InP interface, of a Ni3P layer combined with a stoichiometry change in the InP surface. We show, in addition, that it is possible to achieve very low R(sub c) values with this system without incurring device destroying sinter-induced metallurgical interdiffusion.

Identification of dfrA14 in two distinct plasmids conferring trimethoprim resistance in Actinobacillus pleuropneumoniae.

Science.gov (United States)

Bossé, Janine T; Li, Yanwen; Walker, Stephanie; Atherton, Tom; Fernandez Crespo, Roberto; Williamson, Susanna M; Rogers, Jon; Chaudhuri, Roy R; Weinert, Lucy A; Oshota, Olusegun; Holden, Matt T G; Maskell, Duncan J; Tucker, Alexander W; Wren, Brendan W; Rycroft, Andrew N; Langford, Paul R

2015-08-01

The objective of this study was to determine the distribution and genetic basis of trimethoprim resistance in Actinobacillus pleuropneumoniae isolates from pigs in England. Clinical isolates collected between 1998 and 2011 were tested for resistance to trimethoprim and sulphonamide. The genetic basis of trimethoprim resistance was determined by shotgun WGS analysis and the subsequent isolation and sequencing of plasmids. A total of 16 (out of 106) A. pleuropneumoniae isolates were resistant to both trimethoprim (MIC >32 mg/L) and sulfisoxazole (MIC ≥256 mg/L), and a further 32 were resistant only to sulfisoxazole (MIC ≥256 mg/L). Genome sequence data for the trimethoprim-resistant isolates revealed the presence of the dfrA14 dihydrofolate reductase gene. The distribution of plasmid sequences in multiple contigs suggested the presence of two distinct dfrA14-containing plasmids in different isolates, which was confirmed by plasmid isolation and sequencing. Both plasmids encoded mobilization genes, the sulphonamide resistance gene sul2, as well as dfrA14 inserted into strA, a streptomycin-resistance-associated gene, although the gene order differed between the two plasmids. One of the plasmids further encoded the strB streptomycin-resistance-associated gene. This is the first description of mobilizable plasmids conferring trimethoprim resistance in A. pleuropneumoniae and, to our knowledge, the first report of dfrA14 in any member of the Pasteurellaceae. The identification of dfrA14 conferring trimethoprim resistance in A. pleuropneumoniae isolates will facilitate PCR screens for resistance to this important antimicrobial. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.

Influence of Asymmetric Contact Form on Contact Resistance and Schottky Barrier, and Corresponding Applications of Diode.

Science.gov (United States)

Zhao, Yudan; Xiao, Xiaoyang; Huo, Yujia; Wang, Yingcheng; Zhang, Tianfu; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan; Li, Qunqing

2017-06-07

We have fabricated carbon nanotube and MoS 2 field-effect transistors with asymmetric contact forms of source-drain electrodes, from which we found the current directionality of the devices and different contact resistances under the two current directions. By designing various structures, we can conclude that the asymmetric electrical performance was caused by the difference in the effective Schottky barrier height (Φ SB ) caused by the different contact forms. A detailed temperature-dependent study was used to extract and compare the Φ SB for both contact forms of CNT and MoS 2 devices; we found that the Φ SB for the metal-on-semiconductor form was much lower than that of the semiconductor-on-metal form and is suitable for all p-type, n-type, or ambipolar semiconductors. This conclusion is meaningful with respect to the design and application of nanomaterial electronic devices. Additionally, using the difference in barrier height caused by the contact forms, we have also proposed and fabricated Schottky barrier diodes with a current ratio up to 10 4 ; rectifying circuits consisting of these diodes were able to work in a wide frequency range. This design avoided the use of complex chemical doping or heterojunction methods to achieve fundamental diodes that are relatively simple and use only a single material; these may be suitable for future application in nanoelectronic radio frequency or integrated circuits.

Metabolic and Target-Site Mechanisms Combine to Confer Strong DDT Resistance in Anopheles gambiae

Science.gov (United States)

Mitchell, Sara N.; Rigden, Daniel J.; Dowd, Andrew J.; Lu, Fang; Wilding, Craig S.; Weetman, David; Dadzie, Samuel; Jenkins, Adam M.; Regna, Kimberly; Boko, Pelagie; Djogbenou, Luc; Muskavitch, Marc A. T.; Ranson, Hilary; Paine, Mark J. I.; Mayans, Olga; Donnelly, Martin J.

2014-01-01

The development of resistance to insecticides has become a classic exemplar of evolution occurring within human time scales. In this study we demonstrate how resistance to DDT in the major African malaria vector Anopheles gambiae is a result of both target-site resistance mechanisms that have introgressed between incipient species (the M- and S-molecular forms) and allelic variants in a DDT-detoxifying enzyme. Sequencing of the detoxification enzyme, Gste2, from DDT resistant and susceptible strains of An. gambiae, revealed a non-synonymous polymorphism (I114T), proximal to the DDT binding domain, which segregated with strain phenotype. Recombinant protein expression and DDT metabolism analysis revealed that the proteins from the susceptible strain lost activity at higher DDT concentrations, characteristic of substrate inhibition. The effect of I114T on GSTE2 protein structure was explored through X-ray crystallography. The amino acid exchange in the DDT-resistant strain introduced a hydroxyl group nearby the hydrophobic DDT-binding region. The exchange does not result in structural alterations but is predicted to facilitate local dynamics and enzyme activity. Expression of both wild-type and 114T alleles the allele in Drosophila conferred an increase in DDT tolerance. The 114T mutation was significantly associated with DDT resistance in wild caught M-form populations and acts in concert with target-site mutations in the voltage gated sodium channel (Vgsc-1575Y and Vgsc-1014F) to confer extreme levels of DDT resistance in wild caught An. gambiae. PMID:24675797

Temperature dependence of annealing on the contact resistance of MoS2 with graphene electrodes observed

Science.gov (United States)

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

2018-04-01

Two-dimensional (2D) materials are promising candidates for atomically thin nanoelectronics. Among them, MoS2 has attracted considerable attention in the nanoscience and nanotechnology community owing to its unique characteristics including high electron mobility and intrinsic band gap. In this study, we experimentally explored the contact resistances of MoS2 films based on much layered graphene films as electrodes using the circular transmission line model (CTLM). The variation in the chemical composition of the material is thoroughly analyzed by Raman and X-ray photoelectric spectroscopy (XPS) measurements. Experimental results demonstrate that annealing followed by oxygen plasma treatment can effectively improve the contact resistance. Furthermore, the current-voltage curves measured after different annealing temperatures indicate good linear characteristics, which means a marked improvement in electrical property. Calculations show that a relatively low contact resistance of ˜4.177 kΩ (ignoring its size) without back gate voltage in a single-layer graphene/MoS2 structure at an optimal annealing temperature of 500 °C is achieved. This work about the effect of annealing temperature on contact resistance can also be employed for other 2D materials, which lays a foundation for further development of novel 2D material devices.

Bactobolin resistance is conferred by mutations in the L2 ribosomal protein.

Science.gov (United States)

Chandler, Josephine R; Truong, Thao T; Silva, Patricia M; Seyedsayamdost, Mohammad R; Carr, Gavin; Radey, Matthew; Jacobs, Michael A; Sims, Elizabeth H; Clardy, Jon; Greenberg, E Peter

2012-12-18

Burkholderia thailandensis produces a family of polyketide-peptide molecules called bactobolins, some of which are potent antibiotics. We found that growth of B. thailandensis at 30°C versus that at 37°C resulted in increased production of bactobolins. We purified the three most abundant bactobolins and determined their activities against a battery of bacteria and mouse fibroblasts. Two of the three compounds showed strong activities against both bacteria and fibroblasts. The third analog was much less potent in both assays. These results suggested that the target of bactobolins might be conserved across bacteria and mammalian cells. To learn about the mechanism of bactobolin activity, we isolated four spontaneous bactobolin-resistant Bacillus subtilis mutants. We used genomic sequencing technology to show that each of the four resistant variants had mutations in rplB, which codes for the 50S ribosome-associated L2 protein. Ectopic expression of a mutant rplB gene in wild-type B. subtilis conferred bactobolin resistance. Finally, the L2 mutations did not confer resistance to other antibiotics known to interfere with ribosome function. Our data indicate that bactobolins target the L2 protein or a nearby site and that this is not the target of other antibiotics. We presume that the mammalian target of bactobolins involves the eukaryotic homolog of L2 (L8e). Currently available antibiotics target surprisingly few cellular functions, and there is a need to identify novel antibiotic targets. We have been interested in the Burkholderia thailandensis bactobolins, and we sought to learn about the target of bactobolin activity by mapping spontaneous resistance mutations in the bactobolin-sensitive Bacillus subtilis. Our results indicate that the bactobolin target is the 50S ribosome-associated L2 protein or a region of the ribosome affected by L2. Bactobolin-resistant mutants are not resistant to other known ribosome inhibitors. Our evidence indicates that bactobolins

Error-prone PCR mutation of Ls-EPSPS gene from Liriope spicata conferring to its enhanced glyphosate-resistance.

Science.gov (United States)

Mao, Chanjuan; Xie, Hongjie; Chen, Shiguo; Valverde, Bernal E; Qiang, Sheng

2017-09-01

Liriope spicata (Thunb.) Lour has a unique LsEPSPS structure contributing to the highest-ever-recognized natural glyphosate tolerance. The transformed LsEPSPS confers increased glyphosate resistance to E. coli and A. thaliana. However, the increased glyphosate-resistance level is not high enough to be of commercial value. Therefore, LsEPSPS was subjected to error-prone PCR to screen mutant EPSPS genes capable of endowing higher resistance levels. A mutant designated as ELs-EPSPS having five mutated amino acids (37Val, 67Asn, 277Ser, 351Gly and 422Gly) was selected for its ability to confer improved resistance to glyphosate. Expression of ELs-EPSPS in recombinant E. coli BL21 (DE3) strains enhanced resistance to glyphosate in comparison to both the LsEPSPS-transformed and -untransformed controls. Furthermore, transgenic ELs-EPSPS A. thaliana was about 5.4 fold and 2-fold resistance to glyphosate compared with the wild-type and the Ls-EPSPS-transgenic plants, respectively. Therefore, the mutated ELs-EPSPS gene has potential value for has potential for the development of glyphosate-resistant crops. Copyright © 2016 Elsevier Inc. All rights reserved.

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

Electrical resistivity tomography (ERT) has often been put forward as a promising tool to quantify soil water and solute fluxes in a non-invasive way. In our experiment, we wanted to determine preferential flow processes along a forested hillslope using a saline tracer with ERT. The experiment was conducted in the Houille watershed, subcatchment of the Meuse located in the North of Belgian Ardennes (50° 1'52.6'N, 4° 53'22.5'E). The climate is continental but the soil under spruce (Picea abies (L.) Karst.) and Douglas fire stand (Pseudotsuga menziesii (Mirb.) Franco) remains quite dry (19% WVC in average) during the whole year. The soil is Cambisol and the parent rock is Devonian schist covered with variable thickness of silty loam soil. The soil density ranges from 1.13 to 1.87 g/cm3 on average. The stone content varies from 20 to 89% and the soil depth fluctuates between 70 and 130 cm. The ERT tests took place on June 1st 2012, April 1st, 2nd and 3rd 2014 and May 12th 2014. We used the Terrameter LS 12 channels (ABEM, Sweden) in 2012 test and the DAS-1 (Multi-Phase Technologies, United States) in 2014. Different electrode configurations and arrays were adopted for different dates (transect and grid arrays and Wenner - Schlumberger, Wenner alpha and dipole-dipole configurations). During all tests, we systematically faced technical problems, mainly related to bad electrode contact. The recorded data show values of contact resistance above 14873 Ω (our target value would be below 3000 Ω). Subsequently, we tried to improve the contact by predrilling the soil and pouring water in the electrode holes. The contact resistance improved to 14040 Ω as minimum. The same procedure with liquid mud was then tested to prevent quick percolation of the water from the electrode location. As a result, the lower contact resistance dropped to 11745 Ω. Finally, we applied about 25 litre of saline solution (CaCl2, 0.75g/L) homogeneously on the electrode grid. The minimum value of

MENA Confers Resistance to Paclitaxel in Triple-Negative Breast Cancer.

Science.gov (United States)

Oudin, Madeleine J; Barbier, Lucie; Schäfer, Claudia; Kosciuk, Tatsiana; Miller, Miles A; Han, Sangyoon; Jonas, Oliver; Lauffenburger, Douglas A; Gertler, Frank B

2017-01-01

Taxane therapy remains the standard of care for triple-negative breast cancer. However, high frequencies of recurrence and progression in treated patients indicate that metastatic breast cancer cells can acquire resistance to this drug. The actin regulatory protein MENA and particularly its invasive isoform, MENA INV , are established drivers of metastasis. MENA INV expression is significantly correlated with metastasis and poor outcome in human patients with breast cancer. We investigated whether MENA isoforms might play a role in driving resistance to chemotherapeutics. We find that both MENA and MENA INV confer resistance to the taxane paclitaxel, but not to the widely used DNA-damaging agents doxorubicin or cisplatin. Furthermore, paclitaxel treatment does not attenuate growth of MENA INV -driven metastatic lesions. Mechanistically, MENA isoform expression alters the ratio of dynamic and stable microtubule populations in paclitaxel-treated cells. MENA expression also increases MAPK signaling in response to paclitaxel treatment. Decreasing ERK phosphorylation by co-treatment with MEK inhibitor restored paclitaxel sensitivity by driving microtubule stabilization in MENA isoform-expressing cells. Our results reveal a novel mechanism of taxane resistance in highly metastatic breast cancer cells and identify a combination therapy to overcome such resistance. Mol Cancer Ther; 16(1); 143-55. ©2016 AACR. ©2016 American Association for Cancer Research.

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.

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)

Improving the contact resistance at low force using gold coated carbon nanotube surfaces

Science.gov (United States)

McBride, J. W.; Yunus, E. M.; Spearing, S. M.

2010-04-01

Investigations to determine the electrical contact performance under repeated cycles at low force conditions for carbon-nanotube (CNT) coated surfaces were performed. The surfaces under investigation consisted of multi-walled CNT synthesized on a silicon substrate and coated with a gold film. These planar surfaces were mounted on the tip of a PZT actuator and contacted with a plated Au hemispherical probe. The dynamic applied force used was 1 mN. The contact resistance (Rc) of these surfaces was investigated with the applied force and with repeated loading cycles performed for stability testing. The surfaces were compared with a reference Au-Au contact under the same experimental conditions. This initial study shows the potential for the application of gold coated CNT surfaces as an interface in low force electrical contact applications.

Determination of work function of graphene under a metal electrode and its role in contact resistance.

Science.gov (United States)

Song, Seung Min; Park, Jong Kyung; Sul, One Jae; Cho, Byung Jin

2012-08-08

Although the work function of graphene under a given metal electrode is critical information for the realization of high-performance graphene-based electronic devices, relatively little relevant research has been carried out to date. In this work, the work function values of graphene under various metals are accurately measured for the first time through a detailed analysis of the capacitance-voltage (C-V) characteristics of a metal-graphene-oxide-semiconductor (MGOS) capacitor structure. In contrast to the high work function of exposed graphene of 4.89-5.16 eV, the work function of graphene under a metal electrode varies depending on the metal species. With a Cr/Au or Ni contact, the work function of graphene is pinned to that of the contacted metal, whereas with a Pd or Au contact the work function assumes a value of ∼4.62 eV regardless of the work function of the contact metal. A study of the gate voltage dependence on the contact resistance shows that the latter case provides lower contact resistance.

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

International Nuclear Information System (INIS)

Jeon, Eun Beom; Kim, Hak Sung; Takahashi, Kosuke

2014-01-01

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.

The rice XA21 ectodomain fused to the Arabidopsis EFR cytoplasmic domain confers resistance to Xanthomonas oryzae pv. oryzae.

Science.gov (United States)

Thomas, Nicholas C; Oksenberg, Nir; Liu, Furong; Caddell, Daniel; Nalyvayko, Alina; Nguyen, Yen; Schwessinger, Benjamin; Ronald, Pamela C

2018-01-01

Rice ( Oryza sativa ) plants expressing the XA21 cell-surface receptor kinase are resistant to Xanthomonas oryzae pv. oryzae (Xoo) infection. We previously demonstrated that expressing a chimeric protein containing the ELONGATION FACTOR Tu RECEPTOR (EFR) ectodomain and the XA21 endodomain (EFR:XA21) in rice does not confer robust resistance to Xoo . To test if the XA21 ectodomain is required for Xoo resistance, we produced transgenic rice lines expressing a chimeric protein consisting of the XA21 ectodomain and EFR endodomain (XA21:EFR) and inoculated these lines with Xoo . We also tested if the XA21:EFR rice plants respond to a synthetic sulfated 21 amino acid derivative (RaxX21-sY) of the activator of XA21-mediated immunity, RaxX. We found that five independently transformed XA21:EFR rice lines displayed resistance to Xoo as measured by lesion length analysis, and showed that five lines share characteristic markers of the XA21 defense response (generation of reactive oxygen species and defense response gene expression) after treatment with RaxX21-sY. Our results indicate that expression of the XA21:EFR chimeric receptor in rice confers resistance to Xoo . These results suggest that the endodomain of the EFR and XA21 immune receptors are interchangeable and the XA21 ectodomain is the key determinant conferring robust resistance to Xoo .

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

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.

An Experimental Study on Heat Conduction and Thermal Contact Resistance for the AlN Flake

Directory of Open Access Journals (Sweden)

Huann-Ming Chou

2013-01-01

Full Text Available The electrical technology has been a fast development over the past decades. Moreover, the tendency of microelements and dense division multiplex is significantly for the electrical industries. Therefore, the high thermal conductible and electrical insulating device will be popular and important. It is well known that AlN still maintains stablility in the high temperature. This is quite attractive for the research and development department. Moreover, the thermal conduct coefficient of AlN is several times larger than the others. Therefore, it has been thought to play an important role for the radiator of heat source in the future. Therefore, this paper is focused on the studies of heat conduction and thermal contact resistance between the AlN flake and the copper specimens. The heating temperatures and the contact pressures were selected as the experimental parameters. According to the experimental results, the materials are soft and the real contact areas between the interfaces significantly increase under higher temperatures. As a result, the thermal contact resistance significantly decreases and the heat transfer rate increases with increasing the heating temperature or the contact pressures.

qnrA6 genetic environment and quinolone resistance conferred on Proteus mirabilis.

Science.gov (United States)

Jayol, Aurélie; Janvier, Frédéric; Guillard, Thomas; Chau, Françoise; Mérens, Audrey; Robert, Jérôme; Fantin, Bruno; Berçot, Béatrice; Cambau, Emmanuelle

2016-04-01

To determine the genetic location and environment of the qnrA6 gene in Proteus mirabilis PS16 where it was first described and to characterize the quinolone resistance qnrA6 confers. Transformation experiments and Southern blotting were performed for plasmid and genomic DNA of P. mirabilis PS16 to determine the qnrA6 location. Combinatorial PCRs with primers in qnrA6 and genes usually surrounding qnrA genes were used to determine the genetic environment. The qnrA6 coding region, including or not the promoter region, was cloned into vectors pTOPO and pBR322 and the MICs of six quinolones were measured for transformants of Escherichia coli TOP10 and P. mirabilis ATCC 29906 Rif(R). qnrA6 was shown to be chromosomally encoded in P. mirabilis PS16 and its genetic environment was 81%-87% similar to that of qnrA2 in the Shewanella algae chromosome. The 5138 bp region up- and downstream of qnrA6 contained an IS10 sequence surrounded by two ISCR1. This resulted in qnrA6 being displaced 1.9 kb from its native promoter but supplied a promoter present in ISCR1. qnrA6 cloned into pTOPO and pBR322 conferred a 4-32-fold increase in fluoroquinolone MICs when expressed in E. coli but only 2-3-fold in P. mirabilis. When including the promoter region, a further increase in resistance was observed in both species, reaching MIC values above clinical breakpoints for only P. mirabilis. qnrA6 is the first chromosomally located qnrA gene described in Enterobacteriaceae. The quinolone resistance conferred by qnrA6 depends on the proximity of an efficient promoter and the host strain where it is expressed. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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

Methicillin resistance of airborne coagulase-negative staphylococci in homes of persons having contact with a hospital environment.

Science.gov (United States)

Lis, Danuta O; Pacha, Jerzy Z; Idzik, Danuta

2009-04-01

The persons having contact with a hospital environment (hospital personnel workers and discharged patients) are highly exposed to colonization with multidrug-resistant bacteria. The aim of this study was to evaluate the airborne Staphylococcus genus features in homes in which inhabitants have had contact with the hospital environment. Airborne bacteria were collected using a 6-stage Anderson impactor. The Staphylococcus species composition and resistance to methicillin, and other antimicrobial agents among 3 coagulase-negative staphylococci (CNS) species (S cohnii spp cohnii, S epidermidis, S hominis), were determined. Antibiotic resistance of isolates was tested using the agar screen method with methicillin, the polymerase chain reaction technique to detect the mecA gene, and the disk diffusion method. A higher prevalence of methicillin-resistant (MR) strains among the species isolated (40% of S epidermidis, 40% of S hominis, and 60% of S cohnii spp cohnii) was found in homes of persons who had contact with a hospital environment compared with the reference homes (only 12% of S hominis). The mecA gene was revealed in all MR S epidermidis strains and in some MR S hominis (50%) and S cohnii spp cohnii (33%) strains. All isolated MR CNS strains were susceptible to vancomycin, rifampicin, and linezolid. High numbers of airborne multidrug-resistant MR CNS in the homes of persons having contact with a hospital environment indicates that such inhabitants pose a risk of intrafamilial spreading of MR strains via air.

Molecular characterization of the CRa gene conferring clubroot resistance in Brassica rapa.

Science.gov (United States)

Ueno, Hiroki; Matsumoto, Etsuo; Aruga, Daisuke; Kitagawa, Satoshi; Matsumura, Hideo; Hayashida, Nobuaki

2012-12-01

Clubroot disease is one of the major diseases affecting Brassicaceae crops, and a number of these crops grown commercially, such as Chinese cabbage (Brassica rapa L. ssp. pekinensis), are known to be highly susceptible to clubroot disease. To provide protection from this disease, plant breeders have introduced genes for resistance to clubroot from the European turnip into susceptible lines. The CRa gene confers specific resistance to the clubroot pathogen Plasmodiophora brassicae isolate M85. Fine mapping of the CRa locus using synteny to the Arabidopsis thaliana genome and partial genome sequences of B. rapa revealed a candidate gene encoding a TIR-NBS-LRR protein. Several structural differences in this candidate gene were found between susceptible and resistant lines, and CRa expression was observed only in the resistant line. Four mutant lines lacking clubroot resistance were obtained by the UV irradiation of pollen from a resistant line, and all of these mutant lines carried independent mutations in the candidate TIR-NBS-LRR gene. This genetic and molecular evidence strongly suggests that the identified gene is CRa. This is the first report on the molecular characterization of a clubroot Resistance gene in Brassicaceae and of the disease resistance gene in B. rapa.

Ultralow nonalloyed Ohmic contact resistance to self aligned N-polar GaN high electron mobility transistors by In(Ga)N regrowth

International Nuclear Information System (INIS)

Dasgupta, Sansaptak; Nidhi,; Brown, David F.; Wu, Feng; Keller, Stacia; Speck, James S.; Mishra, Umesh K.

2010-01-01

Ultralow Ohmic contact resistance and a self-aligned device structure are necessary to reduce the effect of parasitic elements and obtain higher f t and f max in high electron mobility transistors (HEMTs). N-polar (0001) GaN HEMTs, offer a natural advantage over Ga-polar HEMTs, in terms of contact resistance since the contact is not made through a high band gap material [Al(Ga)N]. In this work, we extend the advantage by making use of polarization induced three-dimensional electron-gas through regrowth of graded InGaN and thin InN cap in the contact regions by plasma (molecular beam epitaxy), to obtain an ultralow Ohmic contact resistance of 27 Ω μm to a GaN 2DEG.

Complex long-distance effects of mutations that confer linezolid resistance in the large ribosomal subunit

Science.gov (United States)

Fulle, Simone; Saini, Jagmohan S.; Homeyer, Nadine; Gohlke, Holger

2015-01-01

The emergence of multidrug-resistant pathogens will make current antibiotics ineffective. For linezolid, a member of the novel oxazolidinone class of antibiotics, 10 nucleotide mutations in the ribosome have been described conferring resistance. Hypotheses for how these mutations affect antibiotics binding have been derived based on comparative crystallographic studies. However, a detailed description at the atomistic level of how remote mutations exert long-distance effects has remained elusive. Here, we show that the G2032A-C2499A double mutation, located > 10 Å away from the antibiotic, confers linezolid resistance by a complex set of effects that percolate to the binding site. By molecular dynamics simulations and free energy calculations, we identify U2504 and C2452 as spearheads among binding site nucleotides that exert the most immediate effect on linezolid binding. Structural reorganizations within the ribosomal subunit due to the mutations are likely associated with mutually compensating changes in the effective energy. Furthermore, we suggest two main routes of information transfer from the mutation sites to U2504 and C2452. Between these, we observe cross-talk, which suggests that synergistic effects observed for the two mutations arise in an indirect manner. These results should be relevant for the development of oxazolidinone derivatives that are active against linezolid-resistant strains. PMID:26202966

3D Modeling and Testing of Contact Problems in Resistance Welding

DEFF Research Database (Denmark)

Nielsen, Chris Valentin

A generic, electro-thermo-mechanically coupled finite element program is developed for three-dimensional simulation of resistance welding. The developed computer program has reached a level of a complete standalone software that can be utilized as a tool in the analysis of resistance welding...... of resistance welding processes, which cover a wide range of spot welding and projection welding applications. Three-dimensional simulation of spot welding enables the analysis of critical effects like electrode misalignment and shunt effects between consecutive spots. A single-sided spot welding case involving...... three-dimensional contact is also presented. This case was suggested by and discussed with a German steel manufacturer. When it comes to projection welding, a natural need for three-dimensional analysis arises in many cases because of the involved geometries. Cross-wire welding and welding of square...

Transport mechanisms in low-resistance ohmic contacts to p-InP formed by rapid thermal annealing

DEFF Research Database (Denmark)

Clausen, Thomas; Leistiko, Otto

1993-01-01

process is related to interdiffusion and compound formation between the metal elements and the InP. The onset of low specific contact resistance is characterized by a change in the dominant transport mechanism; from predominantly a combination of thermionic emission and field emission to purely thermionic......Thermionic emission across a very small effective Schottky barrier (0-0.2 eV) are reported as being the dominant transport process mechanism in very low-resistance ohmic contacts for conventional AuZn(Ni) metallization systems top-InP formed by rapid thermal annealing. The barrier modulation...

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

77 FR 46374 - National Poultry Improvement Plan; General Conference Committee Meeting and 41st Biennial Conference

Science.gov (United States)

2012-08-03

...] National Poultry Improvement Plan; General Conference Committee Meeting and 41st Biennial Conference AGENCY... notice of a meeting of the General Conference Committee of the National Poultry Improvement Plan (NPIP... CONTACT: Dr. C. Stephen Roney, Senior Coordinator, National Poultry Improvement Plan, VS, APHIS, 1506...

Novel Tn916-like elements confer aminoglycoside/macrolide co-resistance in clinical isolates of Streptococcus gallolyticus ssp. gallolyticus.

Science.gov (United States)

Kambarev, Stanimir; Pecorari, Frédéric; Corvec, Stéphane

2018-02-09

Streptococcus gallolyticus ssp. gallolyticus (Sgg) is a commensal bacterium and an opportunistic pathogen. In humans it has been clinically associated with the incidence of colorectal cancer (CRC) and epidemiologically recognized as an emerging cause of infective endocarditis (IE). The standard therapy of Sgg includes the administration of a penicillin in combination with an aminoglycoside. Even though penicillin-resistant isolates have still not been reported, epidemiological studies have shown that this microbe is a reservoir of multiple acquired genes, conferring resistance to tetracyclines, aminoglycosides, macrolides and glycopeptides. However, the underlying antibiotic resistance mobilome of Sgg remains poorly understood. To investigate the mobile genetic basis of antibiotic resistance in multiresistant clinical Sgg. Isolate NTS31106099 was recovered from a patient with IE and CRC at Nantes University Hospital, France and studied by Illumina WGS and comparative genomics. Molecular epidemiology of the identified mobile element(s) was performed using antibiotic susceptibility testing (AST), PCR, PFGE and WGS. Mobility was investigated by PCR and filter mating. Two novel conjugative transposons, Tn6263 and Tn6331, confer aminoglycoside/macrolide co-resistance in clinical Sgg. They display classical family Tn916/Tn1545 modular architecture and harbour an aph(3')-III→sat4→ant(6)-Ia→erm(B) multiresistance gene cluster, related to pRE25 of Enterococcus faecium. These and/or closely related elements are highly prevalent among genetically heterogeneous clinical isolates of Sgg. Previously unknown Tn916-like mobile genetic elements conferring aminoglycoside/macrolide co-resistance make Sgg, collectively with other gut Firmicutes such as enterococci and eubacteria, a potential laterally active reservoir of these antibiotic resistance determinants among the mammalian gastrointestinal microbiota. © The Author(s) 2018. Published by Oxford University Press on behalf

A novel resistance gene, lnu(H), conferring resistance to lincosamides in Riemerella anatipestifer CH-2.

Science.gov (United States)

Luo, Hong-Yan; Liu, Ma-Feng; Wang, Ming-Shu; Zhao, Xin-Xin; Jia, Ren-Yong; Chen, Shun; Sun, Kun-Feng; Yang, Qiao; Wu, Ying; Chen, Xiao-Yue; Biville, Francis; Zou, Yuan-Feng; Jing, Bo; Cheng, An-Chun; Zhu, De-Kang

2018-01-01

The Gram-negative bacterium Riemerella anatipestifer CH-2 is resistant to lincosamides, having a lincomycin (LCM) minimum inhibitory concentration (MIC) of 128 µg/mL. The G148_1775 gene of R. anatipestifer CH-2, designated lnu(H), encodes a 260-amino acid protein with ≤41% identity to other reported lincosamide nucleotidylyltransferases. Escherichia coli Rosetta TM (DE3) containing the pBAD24-lnu(H) plasmid showed four- and two-fold increases in the MICs of LCM and clindamycin (CLI), respectively. A kinetic assay of the purified Lnu(H) enzyme for LCM and CLI showed that the protein could inactive lincosamides. Mass spectrometry analysis demonstrated that the Lnu(H) enzyme catalysed adenylylation of lincosamides. In addition, an lnu(H) gene deletion strain exhibited 512- and 32-fold decreases in LCM and CLI MICs, respectively. The wild-type level of lincosamide resistance could be restored by complementation with a shuttle plasmid carrying the lnu(H) gene. The transformant R. anatipestifer ATCC 11845 [lnu(H)] acquired by natural transformation also exhibited high-level lincosamide resistance. Moreover, among 175 R. anatipestifer field isolates, 56 (32.0%) were positive for the lnu(H) gene by PCR. In conclusion, Lnu(H) is a novel lincosamide nucleotidylyltransferase that inactivates LCM and CLI by nucleotidylylation, thus conferring high-level lincosamide resistance to R. anatipestifer CH-2. Copyright © 2017. Published by Elsevier B.V.

Reaching consensus on drug resistance conferring mutations (Part 1

Directory of Open Access Journals (Sweden)

Daniela M Cirillo

2016-01-01

A user-friendly interface designed for nonexpert or expert operability.A standardized and validated analysis pipeline for variant analyses of M. tuberculosis next-generation sequencing (NGS data.Access to data beyond the published literature with dynamic and iterative updates of new data generated by global surveillance and clinical trials.A well-developed legal structure to ensure intellectual property rights and data ownership remain with contributors.A structured data-sharing architecture to restrict access to sensitive or unpublished data sets.Metadata standardization using CDISC: supports global, platform-independent data standards that enable information system interoperability.An emphasis on data quality and rigorous, expert curation with multiple quality control checks for whole-genome sequencing and other metadata.Validation of NGS analysis output by an expert committee with grading of resistance conferring mutations based on rigorous statistical standards.Regulatory-compliant analysis pipeline and database architecture. Successful execution of such an extensive database platform requires substantial collaboration from scientists investigating the genetic basis for drug resistance worldwide, and from developers with expertise in database design and implementation.

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.

Phosphine resistance does not confer cross-resistance to sulfuryl fluoride in four major stored grain insect pests.

Science.gov (United States)

Jagadeesan, Rajeswaran; Nayak, Manoj K

2017-07-01

Susceptibility to phosphine (PH 3 ) and sulfuryl fluoride (SF) and cross-resistance to SF were evaluated in two life stages (eggs and adults) of key grain insect pests, Rhyzopertha dominca (F.), Sitophilus oryzae (L.), Cryptolestes ferrugineus (Stephens), and Tribolium castaneum (Herbst). This study was performed with an aim to integrate SF into phosphine resistance management programmes in Australia. Characterisation of susceptibility and resistance to phosphine in eggs and adults showed that C. ferrugineus was the most tolerant as well as resistant species. Mortality responses of eggs and adults to SF at 25 °C revealed T. castaneum to be the most tolerant species followed by S. oryzae, C. ferrugineus and R. dominica. A high dose range of SF, 50.8-62.2 mg L -1 over 48 h, representing c (concentration) × t (time) products of 2438-2985 gh m -3 , was required for complete control of eggs of T. castaneum, whereas eggs of the least tolerant R. dominca required only 630 gh m -3 for 48 h (13.13 mg L -1 ). Mortality response of eggs and adults of phosphine-resistant strains to SF in all four species confirmed the lack of cross-resistance to SF. Our research concludes that phosphine resistance does not confer cross-resistance to SF in grain insect pests irrespective of the variation in levels of tolerance to SF itself or resistance to phosphine in their egg and adult stages. While our study confirms that SF has potential as a 'phosphine resistance breaker', the observed higher tolerance in eggs stresses the importance of developing SF fumigation protocols with longer exposure periods. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

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.

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.

Expression of artificial microRNAs in transgenic Arabidopsis thaliana confers virus resistance.

Science.gov (United States)

Niu, Qi-Wen; Lin, Shih-Shun; Reyes, Jose Luis; Chen, Kuan-Chun; Wu, Hui-Wen; Yeh, Shyi-Dong; Chua, Nam-Hai

2006-11-01

Plant microRNAs (miRNAs) regulate the abundance of target mRNAs by guiding their cleavage at the sequence complementary region. We have modified an Arabidopsis thaliana miR159 precursor to express artificial miRNAs (amiRNAs) targeting viral mRNA sequences encoding two gene silencing suppressors, P69 of turnip yellow mosaic virus (TYMV) and HC-Pro of turnip mosaic virus (TuMV). Production of these amiRNAs requires A. thaliana DICER-like protein 1. Transgenic A. thaliana plants expressing amiR-P69(159) and amiR-HC-Pro(159) are specifically resistant to TYMV and TuMV, respectively. Expression of amiR-TuCP(159) targeting TuMV coat protein sequences also confers specific TuMV resistance. However, transgenic plants that express both amiR-P69(159) and amiR-HC-Pro(159) from a dimeric pre-amiR-P69(159)/amiR-HC-Pro(159) transgene are resistant to both viruses. The virus resistance trait is displayed at the cell level and is hereditable. More important, the resistance trait is maintained at 15 degrees C, a temperature that compromises small interfering RNA-mediated gene silencing. The amiRNA-mediated approach should have broad applicability for engineering multiple virus resistance in crop plants.

A comparative study of the electrical properties of Pd/ZnO Schottky contacts fabricated using electron beam deposition and resistive/thermal evaporation techniques

International Nuclear Information System (INIS)

Mtangi, W.; Auret, F. D.; Janse van Rensburg, P. J.; Coelho, S. M. M.; Legodi, M. J.; Nel, J. M.; Meyer, W. E.; Chawanda, A.

2011-01-01

A systematic investigation to check the quality of Pd Schottky contacts deposited on ZnO has been performed on electron beam (e-beam) deposited and resistively/thermally evaporated samples using current-voltage, IV, and conventional deep level transient spectroscopy (DLTS) measurements. Room temperature IV measurements reveal the dominance of pure thermionic emission on the resistively evaporated contacts, while the e-beam deposited contacts show the dominance of generation recombination at low voltages, -10 A at a reverse voltage of 1.0 V whereas the e-beam deposited contacts have reverse currents of the order of 10 -6 A at 1.0 V. Average ideality factors have been determined as (1.43 ± 0.01) and (1.66 ± 0.02) for the resistively evaporated contacts and e-beam deposited contacts, respectively. The IV barrier heights have been calculated as (0.721 ± 0.002) eV and (0.624 ± 0.005) eV for the resistively evaporated and e-beam deposited contacts, respectively. Conventional DLTS measurements reveal the presence of three prominent defects in both the resistive and e-beam contacts. Two extra peaks with energy levels of 0.60 and 0.81 eV below the conduction band minimum have been observed in the e-beam deposited contacts. These have been explained as contributing to the generation recombination current that dominates at low voltages and high leakage currents. Based on the reverse current at 1.0 V, the degree of rectification, the dominant current transport mechanism and the observed defects, we conclude that the resistive evaporation technique yields better quality Schottky contacts for use in solar cells and ultraviolet detectors compared to the e-beam deposition technique. The 0.60 eV has been identified as possibly related to the unoccupied level for the doubly charged oxygen vacancy, V o 2+ .

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.

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.

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)

The wheat Lr34 multipathogen resistance gene confers resistance to anthracnose and rust in sorghum.

Science.gov (United States)

Schnippenkoetter, Wendelin; Lo, Clive; Liu, Guoquan; Dibley, Katherine; Chan, Wai Lung; White, Jodie; Milne, Ricky; Zwart, Alexander; Kwong, Eunjung; Keller, Beat; Godwin, Ian; Krattinger, Simon G; Lagudah, Evans

2017-11-01

The ability of the wheat Lr34 multipathogen resistance gene (Lr34res) to function across a wide taxonomic boundary was investigated in transgenic Sorghum bicolor. Increased resistance to sorghum rust and anthracnose disease symptoms following infection with the biotrophic pathogen Puccinia purpurea and the hemibiotroph Colletotrichum sublineolum, respectively, occurred in transgenic plants expressing the Lr34res ABC transporter. Transgenic sorghum lines that highly expressed the wheat Lr34res gene exhibited immunity to sorghum rust compared to the low-expressing single copy Lr34res genotype that conferred partial resistance. Pathogen-induced pigmentation mediated by flavonoid phytoalexins was evident on transgenic sorghum leaves following P. purpurea infection within 24-72 h, which paralleled Lr34res gene expression. Elevated expression of flavone synthase II, flavanone 4-reductase and dihydroflavonol reductase genes which control the biosynthesis of flavonoid phytoalexins characterized the highly expressing Lr34res transgenic lines 24-h post-inoculation with P. purpurea. Metabolite analysis of mesocotyls infected with C. sublineolum showed increased levels of 3-deoxyanthocyanidin metabolites were associated with Lr34res expression, concomitant with reduced symptoms of anthracnose. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

International Nuclear Information System (INIS)

Shaforost, O.; Wang, K.; Adabi, M.; Guo, Z.; Hanham, S.; Klein, N.; Goniszewski, S.; Gallop, J.; Hao, L.

2015-01-01

A method for contact-free determination of the sheet resistance of large-area and arbitrary shaped wafers or sheets coated with graphene and other (semi) conducting ultrathin layers is described, which is based on an open dielectric loaded microwave cavity. The sample under test is exposed to the evanescent resonant field outside the cavity. A comparison with a closed cavity configuration revealed that radiation losses have no significant influence of the experimental results. Moreover, the microwave sheet resistance results show good agreement with the dc conductivity determined by four-probe van der Pauw measurements on a set of CVD samples transferred on quartz. As an example of a practical application, correlations between the sheet resistance and deposition conditions for CVD graphene transferred on quartz wafers are described. Our method has a high potential as measurement standard for contact-free sheet resistance measurement and mapping of large area graphene samples

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...

NRF2 Mutation Confers Malignant Potential and Resistance to Chemoradiation Therapy in Advanced Esophageal Squamous Cancer

Directory of Open Access Journals (Sweden)

Tatsuhiro Shibata

2011-09-01

Full Text Available Esophageal squamous cancer (ESC is one of the most aggressive tumors of the gastrointestinal tract. A combination of chemotherapy and radiation therapy (CRT has improved the clinical outcome, but the molecular background determining the effectiveness of therapy remains unknown. NRF2 is a master transcriptional regulator of stress adaptation, and gain of-function mutation of NRF2 in cancer confers resistance to stressors including anticancer therapy. Direct resequencing analysis revealed that Nrf2 gain-of-function mutation occurred recurrently (18/82, 22% in advanced ESC tumors and ESC cell lines (3/10. The presence of Nrf2 mutation was associated with tumor recurrence and poor prognosis. Short hairpin RNA-mediated down-regulation of NRF2 in ESC cells that harbor only mutated Nrf2 allele revealed that themutant NRF2 conferred increased cell proliferation, attachment-independent survival, and resistance to 5-fluorouracil and γ-irradiation. Based on the Nrf2 mutation status, gene expression signatures associated with NRF2 mutation were extracted from ESC cell lines, and their potential utility for monitoring and prognosis was examined in a cohort of 33 pre-CRT cases of ESC. The molecular signatures of NRF2 mutation were significantly predictive and prognostic for CRT response. In conclusion, recurrent NRF2 mutation confers malignant potential and resistance to therapy in advanced ESC, resulting in a poorer outcome. Molecular signatures of NRF2 mutation can be applied as predictive markers of response to CRT, and efficient inhibition of aberrant NRF2 activation could be a promising approach in combination with CRT.

Loss of the RNA polymerase III repressor MAF1 confers obesity resistance.

OpenAIRE

Bonhoure, N.; Byrnes, A.; Moir, R.D.; Hodroj, W.; Preitner, F.; Praz, V.; Marcelin, G.; Chua, S.C.; Martinez-Lopez, N.; Singh, R.; Moullan, N.; Auwerx, J.; Willemin, G.; Shah, H.; Hartil, K.

2015-01-01

MAF1 is a global repressor of RNA polymerase III transcription that regulates the expression of highly abundant noncoding RNAs in response to nutrient availability and cellular stress. Thus, MAF1 function is thought to be important for metabolic economy. Here we show that a whole-body knockout of Maf1 in mice confers resistance to diet-induced obesity and nonalcoholic fatty liver disease by reducing food intake and increasing metabolic inefficiency. Energy expenditure in Maf1(-/-) mice is inc...

The NB-LRR gene Pm60 confers powdery mildew resistance in wheat.

Science.gov (United States)

Zou, Shenghao; Wang, Huan; Li, Yiwen; Kong, Zhaosheng; Tang, Dingzhong

2018-04-01

Powdery mildew is one of the most devastating diseases of wheat. To date, few powdery mildew resistance genes have been cloned from wheat due to the size and complexity of the wheat genome. Triticum urartu is the progenitor of the A genome of wheat and is an important source for powdery mildew resistance genes. Using molecular markers designed from scaffolds of the sequenced T. urartu accession and standard map-based cloning, a powdery mildew resistance locus was mapped to a 356-kb region, which contains two nucleotide-binding and leucine-rich repeat domain (NB-LRR) protein-encoding genes. Virus-induced gene silencing, single-cell transient expression, and stable transformation assays demonstrated that one of these two genes, designated Pm60, confers resistance to powdery mildew. Overexpression of full-length Pm60 and two allelic variants in Nicotiana benthamiana leaves induced hypersensitive cell death response, but expression of the coiled-coil domain alone was insufficient to induce hypersensitive response. Yeast two-hybrid, bimolecular fluorescence complementation and luciferase complementation imaging assays showed that Pm60 protein interacts with its neighboring NB-containing protein, suggesting that they might be functionally related. The identification and cloning of this novel wheat powdery mildew resistance gene will facilitate breeding for disease resistance in wheat. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

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.

A New Ala-122-Asn Amino Acid Change Confers Decreased Fitness to ALS-Resistant Echinochloa crus-galli

Directory of Open Access Journals (Sweden)

Silvia Panozzo

2017-11-01

Full Text Available Gene mutations conferring herbicide resistance may cause pleiotropic effects on plant fitness. Knowledge of these effects is important for managing the evolution of herbicide-resistant weeds. An Echinochloa crus-galli population resistant to acetolactate synthase (ALS herbicides was collected in a maize field in north-eastern Italy and the cross-resistance pattern, resistance mechanism and fitness costs associated to mutant-resistant plants under field conditions in the presence or absence of intra-specific competition were determined. The study reports for the first time the Ala-122-Asn amino-acid change in the ALS gene that confers high levels of cross-resistance to all ALS inhibitors tested. Results of 3-year growth analysis showed that mutant resistant E. crus-galli plants had a delayed development in comparison with susceptible plants and this was registered in both competitive (3, 7, and 20 plants m-2 and non-competitive (spaced plants situations. The number of panicles produced by resistant plants was also lower (about 40% fewer panicles than susceptible plants under no-intraspecific competition. Instead, with the increasing competition level, the difference in panicle production at harvest time decreased until it became negligible at 20 plants m-2. Evaluation of total dry biomass as well as biomass allocation in vegetative parts did not highlight any difference between resistant and susceptible plants. Instead, panicle dry weight was higher in susceptible plants indicating that they allocated more biomass than resistant ones to the reproductive organs, especially in no-competition and in competition situations at lower plant densities. The different fitness between resistant and susceptible phenotypes suggests that keeping the infestation density as low as possible can increase the reproduction success of the susceptible phenotype and therefore contribute to lowering the ratio between resistant and susceptible alleles. If adequately

A New Ala-122-Asn Amino Acid Change Confers Decreased Fitness to ALS-Resistant Echinochloa crus-galli.

Science.gov (United States)

Panozzo, Silvia; Scarabel, Laura; Rosan, Valentina; Sattin, Maurizio

2017-01-01

Gene mutations conferring herbicide resistance may cause pleiotropic effects on plant fitness. Knowledge of these effects is important for managing the evolution of herbicide-resistant weeds. An Echinochloa crus-galli population resistant to acetolactate synthase (ALS) herbicides was collected in a maize field in north-eastern Italy and the cross-resistance pattern, resistance mechanism and fitness costs associated to mutant-resistant plants under field conditions in the presence or absence of intra-specific competition were determined. The study reports for the first time the Ala-122-Asn amino-acid change in the ALS gene that confers high levels of cross-resistance to all ALS inhibitors tested. Results of 3-year growth analysis showed that mutant resistant E. crus-galli plants had a delayed development in comparison with susceptible plants and this was registered in both competitive (3, 7, and 20 plants m -2 ) and non-competitive (spaced plants) situations. The number of panicles produced by resistant plants was also lower (about 40% fewer panicles) than susceptible plants under no-intraspecific competition. Instead, with the increasing competition level, the difference in panicle production at harvest time decreased until it became negligible at 20 plants m -2 . Evaluation of total dry biomass as well as biomass allocation in vegetative parts did not highlight any difference between resistant and susceptible plants. Instead, panicle dry weight was higher in susceptible plants indicating that they allocated more biomass than resistant ones to the reproductive organs, especially in no-competition and in competition situations at lower plant densities. The different fitness between resistant and susceptible phenotypes suggests that keeping the infestation density as low as possible can increase the reproduction success of the susceptible phenotype and therefore contribute to lowering the ratio between resistant and susceptible alleles. If adequately embedded in a

Contact Resistance Reduction of ZnO Thin Film Transistors (TFTs) with Saw-Shaped Electrode

KAUST Repository

Park, Woojin; Shaikh, Sohail F.; Min, Jungwook; Lee, Sang Kyung; Lee, Byoung Hun; Hussain, Muhammad Mustafa

2018-01-01

an enhancement in the output drive current by 50% and reduction in the contact resistance by over 50%, when compared to a typical shaped electrode ZnO TFT consuming the same chip area. This performance enhancement is attributed to extension of channel width

The Cfr rRNA methyltransferase confers resistance to Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A antibiotics

DEFF Research Database (Denmark)

Long, K. S.; Poehlsgaard, Jacob; Kehrenberg, C.

2006-01-01

to overlapping sites at the peptidyl transferase center that abut nucleotide A2503, is perturbed upon Cfr-mediated methylation. Decreased drug binding to Cfr-methylated ribosomes has been confirmed by footprinting analysis. No other rRNA methyltransferase is known to confer resistance to five chemically distinct...

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.

Durable broad-spectrum powdery mildew resistance in pea er1 plants is conferred by natural loss-of-function mutations in PsMLO1

NARCIS (Netherlands)

Humphry, M.; Reinstädler, A.; Ivanov, S.; Bisseling, T.; Panstruga, R.

2011-01-01

Loss-of-function alleles of plant-specific MLO (Mildew Resistance Locus O) genes confer broad-spectrum powdery mildew resistance in monocot (barley) and dicot (Arabidopsis thaliana, tomato) plants. Recessively inherited powdery mildew resistance in pea (Pisum sativum) er1 plants is, in many aspects,

Analysis of acetohydroxyacid synthase1 gene in chickpea conferring resistance to imazamox herbicide.

Science.gov (United States)

Jain, Parul; Tar'an, Bunyamin

2014-11-01

Chickpea (Cicer arietinum L.) production in the Canadian prairies is challenging due to a lack of effective weed management mainly because of poor competition ability of the crop and limited registered herbicide options. Chickpea genotype with resistance to imidazolinone (IMI) herbicides has been identified. A point mutation in the acetohydroxyacid synthase1 (AHAS1) gene at C581 to T581, resulting in an amino acid substitution from Ala194 to Val194 (position 205, standardized to arabidopsis), confers the resistance to imazamox in chickpea. However, the molecular mechanism leading to the resistance is not fully understood. In many plant species, contrasting transcription levels of AHAS gene has been implicated in the resistant and susceptible genotypes in response to IMI. The objectives of this research were to compare the AHAS gene expression and AHAS enzyme activity in resistant and susceptible chickpea cultivars in response to imazamox herbicide treatment. Results from RT-qPCR indicated that there is no significant change in the transcript levels of AHAS1 between the susceptible and the resistant genotypes in response to imazamox treatment. Protein hydrophobic cluster analysis, protein-ligand docking analysis, and AHAS enzyme activity assay all indicated that the resistance to imazamox in chickpea is due to the alteration of interaction of the AHAS1 enzyme with the imazamox herbicide.

Coordinate transformation in the model of long Josephson contacts: geometrically equivalent contacts

International Nuclear Information System (INIS)

Semerdzhieva, E.G.; Boyadzhiev, T.L.; ); Shukrinov, Yu.M.; Physical Technical Institute Dushanbe, 734063

2005-01-01

The transition from model of long Josephson variable-width contact to the contact model with coordinate-dependent Josephson current amplitude is realized by transforming the coordinates. This sets up a correspondence between Josephson contacts of variable width and quasi-one-dimensional contacts of variable thickness barrier layer. It is shown, that for contacts of exponentially varying width the barrier layer of the corresponding quasi-one-dimensional contact contains the distributed resistive inhomogeneity which is an attractor to magnetic flux vortices. With numerical experiments, a 'critical current-magnetic field' dependence for a resistive microinhomogeneity Josephson contact was plotted, and its comparison with the critical curve for a contact of exponentially varying width was made. Thus, this demonstrates that the distributed inhomogeneity may be replaced by a local one at the JC end what technologically, may offer definite advantages

Low-resistance and highly transparent Ag/IZO ohmic contact to p-type GaN

Energy Technology Data Exchange (ETDEWEB)

Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.k [Department of Display Materials Engineering, Kyung Hee University, 1 Seochoen-dong, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Yi, Min-Su [Department of Materials Science and Engineering, Kyungpook National University, Sangju, Gyeongbuk, 742-711 (Korea, Republic of); Lee, Sung-Nam [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan, 617-736 (Korea, Republic of)

2009-05-29

The electrical, structural, and optical characteristics of Ag/ZnO-doped In{sub 2}O{sub 3} (IZO) ohmic contacts to p-type GaN:Mg (2.5 x 10{sup 17} cm{sup -3}) were investigated. The Ag and IZO (10 nm/50 nm) layers were prepared by thermal evaporation and linear facing target sputtering, respectively. Although the as-deposited and 400 {sup o}C annealed samples showed rectifying behavior, the 500 and 600 {sup o}C annealed samples showed linear I-V characteristics indicative of the formation of an ohmic contact. The annealing of the contact at 600 {sup o}C for 3 min in a vacuum ({approx} 10{sup -3} Torr) resulted in the lowest specific contact resistivity of 1.8 x 10{sup -4} {Omega}.cm{sup 2} and high transparency of 78% at a wavelength of 470 nm. Using Auger electron spectroscopy, depth profiling and synchrotron X-ray scattering analysis, we suggested a possible mechanism to explain the annealing dependence of the electrical properties of the Ag/IZO contacts.

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.

5th Contact Mechanics International Symposium

CERN Document Server

2013-01-01

Contact mechanics is an active research area with deep theoretical and numerical roots. The links between nonsmooth analysis and optimization with mechanics have been investigated intensively during the last decades, especially in Europe. The study of complementarity problems, variational -, quasivariational- and hemivariational inequalities arising in contact mechanics and beyond is a hot topic for interdisciplinary research and cooperation. The needs of industry for robust solution algorithms suitable for large scale applications and the regular updates of the respective elements in major commercial computational mechanics codes, demonstrate that this interaction is not restricted to the academic environment. The contributions of this book have been selected from the participants of the CMIS 2009 international conference which took place in Crete and continued a successful series of specialized contact mechanics conferences.

Identification of a rice gene (Bph 1) conferring resistance to brown planthopper (Nilaparvata lugens Stal) using STS markers.

Science.gov (United States)

Kim, Suk-Man; Sohn, Jae-Keun

2005-08-31

This study was carried out to identify a high-resolution marker for a gene conferring resistance to brown planthopper (BPH) biotype 1, using japonica type resistant lines. Bulked segregant analyses were conducted using 520 RAPD primers to identify RAPD fragments linked to the BPH resistance gene. Eleven RAPDs were shown to be polymorphic amplicons between resistant and susceptible progeny. One of these primers, OPE 18, which amplified a 923 bp band tightly linked to resistance, was converted into a sequence-tagged-site (STS) marker. The STS marker, BpE18-3, was easily detectable as a dominant band with tight linkage (3.9cM) to Bph1. It promises to be useful as a marker for assisted selection of resistant progeny in backcross breeding programs to introgress the resistance gene into elite japonica cultivars.

Resistance to nitrofurantoin and UV-irradiation in recA; uvrA; and uvrA, lexA, Escherichia coli mutants conferred by an R-plasmid from an Escherichia coli clinical isolate

Energy Technology Data Exchange (ETDEWEB)

Obaseiki-Ebor, E.E. (Univ. of Benin, Benin City (Nigeria). Faculty of Pharmacy, Dept. of Pharmaceutical Microbiology)

1984-01-01

There have been some reports of R-plasmids conferring nitrofuran resistance by decreasing the reduction of nitrofurantoin. The mechanism by which these R-plasmids mediate nitrofurantoin resistance is still not properly understood. Since DNA repair mutants are very sensitive to nitrofurantoin, it was therefore of interest to see whether R-plasmids conferring nitrofurantoin resistance affected the nitrofurantoin sensitivity of recA; uvrA and uvrA, lexA strains of E. coli K-12. Protection against UV-irradiation was also estimated. The experiments showed that the nitrofurantoin resistance conferred by R-plasmid pBN105 was not due to defective nitrofurantoin reduction or altered permeability of the cell. Because it is known that repair-deficient bacteria have increased susceptibility to nitrofurantoin, it may be suggested that the mechanisms of UV and nitrofurantoin protection conferred by pBN105 to the DNA repair mutant strains are related.

Resistance to nitrofurantoin and UV-irradiation in recA; uvrA; and uvrA, lexA, Escherichia coli mutants conferred by an R-plasmid from an Escherichia coli clinical isolate

International Nuclear Information System (INIS)

Obaseiki-Ebor, E.E.

1984-01-01

There have been some reports of R-plasmids conferring nitrofuran resistance by decreasing the reduction of nitrofurantoin. The mechanism by which these R-plasmids mediate nitrofurantoin resistance is still not properly understood. Since DNA repair mutants are very sensitive to nitrofurantoin, it was therefore of interest to see whether R-plasmids conferring nitrofurantoin resistance affected the nitrofurantoin sensitivity of recA; uvrA and uvrA, lexA strains of E. coli K-12. Protection against UV-irradiation was also estimated. The experiments showed that the nitrofurantoin resistance conferred by R-plasmid pBN105 was not due to defective nitrofurantoin reduction or altered permeability of the cell. Because it is known that repair-deficient bacteria have increased susceptibility to nitrofurantoin, it may be suggested that the mechanisms of UV and nitrofurantoin protection conferred by pBN105 to the DNA repair mutant strains are related. (Auth.)

Reduction of Ag–Si electrical contact resistance by selective RF heating

International Nuclear Information System (INIS)

De Wijs, W-J A; Ljevar, S; Van de Sande, M J; De With, G

2016-01-01

Fast and selective inductive heating of pre-sintered silver lines on silicon as present in solar cells using 27 MHz radio-frequency inductive fields is shown. IR measurements of silicon substrates show that above 450 °C the heating rate of the samples increases sharply, indicating that both the silver and the silicon are heated. By moving the substrate with respect to the RF antenna and modulation of the RF field, silicon wafers were heated reproducibly above 450 °C with heating rates in excess of 200 °C s −1 . Furthermore, selective heating of lines of pre-sintered silver paste was shown below the 450 °C threshold on silicon substrates. The orientation of the silver tracks relative to the RF antenna appeared to be crucial for homogeneity of heating. Transmission line measurements show a clear effect on contact formation between the silver lines and the silicon substrate. To lower the contact resistance sufficiently for industrial feasibility, a high temperature difference between the Si substrate and the Ag tracks is required. The present RF heating process does not match the time scale needed for contact formation between silver and silicon sufficiently, but the significantly improved process control achieved shows promise for applications requiring fast heating and cooling rates. (paper)

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

Silencing of copine genes confers common wheat enhanced resistance to powdery mildew.

Science.gov (United States)

Zou, Baohong; Ding, Yuan; Liu, He; Hua, Jian

2018-06-01

Powdery mildew, caused by the biotrophic fungal pathogen Blumeria graminis f. sp. tritici (Bgt), is a major threat to the production of wheat (Triticum aestivum). It is of great importance to identify new resistance genes for the generation of Bgt-resistant or Bgt-tolerant wheat varieties. Here, we show that the wheat copine genes TaBON1 and TaBON3 negatively regulate wheat disease resistance to Bgt. Two copies of TaBON1 and three copies of TaBON3, located on chromosomes 6AS, 6BL, 1AL, 1BL and 1DL, respectively, were identified from the current common wheat genome sequences. The expression of TaBON1 and TaBON3 is responsive to both pathogen infection and temperature changes. Knocking down of TaBON1 or TaBON3 by virus-induced gene silencing (VIGS) induces the up-regulation of defence responses in wheat. These TaBON1- or TaBON3-silenced plants exhibit enhanced wheat disease resistance to Bgt, accompanied by greater accumulation of hydrogen peroxide and heightened cell death. In addition, high temperature has little effect on the up-regulation of defence response genes conferred by the silencing of TaBON1 or TaBON3. Our study shows a conserved function of plant copine genes in plant immunity and provides new genetic resources for the improvement of resistance to powdery mildew in wheat. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES

International Nuclear Information System (INIS)

Kawagoe, A.; Kawabata, Y.; Sumiyoshi, F.; Nagaya, S.; Hirano, N.

2006-01-01

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES coils were evaluated from a comparison between measured data and 2D-FEM analyses on interstrand coupling losses in these cables. The cables were composed of 30 non-twisted Bi-2212 strands with a diameter of 0.81 mm and a cable twist pitch of 90 mm. Three samples were measured; one of them had NiCr cores and the others had no cores. One of the latter two samples repeatedly experienced bending. The interstrand coupling losses were measured in liquid helium for the straight samples under transverse ac ripple magnetic fields superposed on dc bias magnetic fields. The transverse magnetic field was applied to the samples in directions both perpendicular and parallel to the flat face of the cable. The effect of the bending on the interstrand coupling losses could be neglected for the non-cored samples. The interstrand coupling losses of NiCr cored sample decreased by about 30% compared with the non-cored samples, in case the direction of the transverse magnetic fields applied to the cable is perpendicular to the flat face of the cable. Using these results and 2D-FEM analyses, taking into account that interstrand contact conditions vary from the center to the edge in the cross-section of cables, gave us the conclusion that the between side-by-side strands contact with metallurgical bond only in both edges of the cables

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES

Science.gov (United States)

Kawagoe, A.; Kawabata, Y.; Sumiyoshi, F.; Nagaya, S.; Hirano, N.

2006-10-01

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES coils were evaluated from a comparison between measured data and 2D-FEM analyses on interstrand coupling losses in these cables. The cables were composed of 30 non-twisted Bi-2212 strands with a diameter of 0.81 mm and a cable twist pitch of 90 mm. Three samples were measured; one of them had NiCr cores and the others had no cores. One of the latter two samples repeatedly experienced bending. The interstrand coupling losses were measured in liquid helium for the straight samples under transverse ac ripple magnetic fields superposed on dc bias magnetic fields. The transverse magnetic field was applied to the samples in directions both perpendicular and parallel to the flat face of the cable. The effect of the bending on the interstrand coupling losses could be neglected for the non-cored samples. The interstrand coupling losses of NiCr cored sample decreased by about 30% compared with the non-cored samples, in case the direction of the transverse magnetic fields applied to the cable is perpendicular to the flat face of the cable. Using these results and 2D-FEM analyses, taking into account that interstrand contact conditions vary from the center to the edge in the cross-section of cables, gave us the conclusion that the between side-by-side strands contact with metallurgical bond only in both edges of the cables.

Identification and characterization of Sr13, a tetraploid wheat gene that confers resistance to the Ug99 stem rust race group

Science.gov (United States)

The Puccinia graminis f. sp. tritici (Pgt) Ug99 race group is virulent to most stem rust resistance genes currently deployed in wheat and poses a serious threat to global wheat production. The durum wheat (Triticum turgidum ssp. durum) gene Sr13 confers resistance to Ug99 in addition to virulent rac...

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

KAUST Repository

Almuhammadi, Khaled Hamdan; Lubineau, Gilles; Alfano, Marco Francesco; Buttner, Ulrich

2016-01-01

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

Expression of the Bs2 pepper gene confers resistance to bacterial spot disease in tomato.

Science.gov (United States)

Tai, T H; Dahlbeck, D; Clark, E T; Gajiwala, P; Pasion, R; Whalen, M C; Stall, R E; Staskawicz, B J

1999-11-23

The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The involvement of avrBs2 in pathogen fitness and its prevalence in many X. campestris pathovars suggests that the Bs2 gene may be durable in the field and provide resistance when introduced into other plant species. Employing a positional cloning strategy, the Bs2 locus was isolated and the gene was identified by coexpression with avrBs2 in an Agrobacterium-mediated transient assay. A single candidate gene, predicted to encode motifs characteristic of the nucleotide binding site-leucine-rich repeat class of resistance genes, was identified. This gene specifically controlled the hypersensitive response when transiently expressed in susceptible pepper and tomato lines and in a nonhost species, Nicotiana benthamiana, and was designated as Bs2. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species.

A new point mutation in the iron-sulfur subunit of succinate dehydrogenase confers resistance to boscalid in Sclerotinia sclerotiorum.

Science.gov (United States)

Wang, Yong; Duan, Yabing; Wang, Jianxin; Zhou, Mingguo

2015-09-01

Research has established that mutations in highly conserved amino acids of the succinate dehydrogenase (SDH) complex in various fungi confer SDH inhibitor (SDHI) resistance. For Sclerotinia sclerotiorum (Lib.) de Bary, a necrotrophic fungus with a broad host range and a worldwide distribution, boscalid resistance has been attributed to the mutation H132R in the highly conserved SdhD subunit protein of the SDH complex. In our previous study, however, only one point mutation, A11V in SdhB (GCA to GTA change in SdhB), was detected in S. sclerotiorum boscalid-resistant (BR) mutants. In the current study, replacement of the SdhB gene in a boscalid-sensitive (BS) S. sclerotiorum strain with the mutant SdhB gene conferred resistance. Compared with wild-type strains, BR and GSM (SdhB gene in the wild-type strain replaced by the mutant SdhB gene) mutants were more sensitive to osmotic stress, lacked the ability to produce sclerotia and exhibited lower expression of the pac1 gene. Importantly, the point mutation was not located in the highly conserved sequence of the iron-sulfur subunit of SDH. These results suggest that resistance based on non-conserved vs. conserved protein domains differs in mechanism. In addition to increasing our understanding of boscalid resistance in S. sclerotiorum, the new information will be useful for the development of alternative antifungal drugs. © 2014 BSPP AND JOHN WILEY & SONS LTD.

Lack of the purinergic receptor P2X7 results in resistance to contact hypersensitivity

Science.gov (United States)

Weber, Felix C.; Esser, Philipp R.; Müller, Tobias; Ganesan, Jayanthi; Pellegatti, Patrizia; Simon, Markus M.; Zeiser, Robert; Idzko, Marco; Jakob, Thilo

2010-01-01

Sensitization to contact allergens requires activation of the innate immune system by endogenous danger signals. However, the mechanisms through which contact allergens activate innate signaling pathways are incompletely understood. In this study, we demonstrate that mice lacking the adenosine triphosphate (ATP) receptor P2X7 are resistant to contact hypersensitivity (CHS). P2X7-deficient dendritic cells fail to induce sensitization to contact allergens and do not release IL-1β in response to lipopolysaccharide (LPS) and ATP. These defects are restored by pretreatment with LPS and alum in an NLRP3- and ASC-dependent manner. Whereas pretreatment of wild-type mice with P2X7 antagonists, the ATP-degrading enzyme apyrase or IL-1 receptor antagonist, prevents CHS, IL-1β injection restores CHS in P2X7-deficient mice. Thus, P2X7 is a crucial receptor for extracellular ATP released in skin in response to contact allergens. The lack of P2X7 triggering prevents IL-1β release, which is an essential step in the sensitization process. Interference with P2X7 signaling may be a promising strategy for the prevention of allergic contact dermatitis. PMID:21059855

Introgression and pyramiding into common bean market class fabada of genes conferring resistance to anthracnose and potyvirus.

Science.gov (United States)

Ferreira, Juan José; Campa, Ana; Pérez-Vega, Elena; Rodríguez-Suárez, Cristina; Giraldez, Ramón

2012-03-01

Anthracnose and bean common mosaic (BCM) are considered major diseases in common bean crop causing severe yield losses worldwide. This work describes the introgression and pyramiding of genes conferring genetic resistance to BCM and anthracnose local races into line A25, a bean genotype classified as market class fabada. Resistant plants were selected using resistance tests or combining resistance tests and marker-assisted selection. Lines A252, A321, A493, Sanilac BC6-Are, and BRB130 were used as resistance sources. Resistance genes to anthracnose (Co-2 ( C ), Co-2 ( A252 ) and Co-3/9) and/or BCM (I and bc-3) were introgressed in line A25 through six parallel backcrossing programs, and six breeding lines showing a fabada seed phenotype were obtained after six backcross generations: line A1258 from A252; A1231 from A321; A1220 from A493; A1183 and A1878 from Sanilac BC6-Are; and line A2418 from BRB130. Pyramiding of different genes were developed using the pedigree method from a single cross between lines obtained in the introgression step: line A1699 (derived from cross A1258 × A1220), A2438 (A1220 × A1183), A2806 (A1878 × A2418), and A3308 (A1699 × A2806). A characterization based on eight morpho-agronomic traits revealed a limited differentiation among the obtained breeding lines and the recurrent line A25. However, using a set of seven molecular markers linked to the loci used in the breeding programs it was possible to differentiate the 11 fabada lines. Considering the genetic control of the resistance in resistant donor lines, the observed segregations in the last backcrossing generation, the reaction against the pathogens, and the expression of the molecular markers it was also possible to infer the genotype conferring resistance in the ten fabada breeding lines obtained. As a result of these breeding programs, genetic resistance to three anthracnose races controlled by genes included in clusters Co-2 and Co-3/9, and genetic resistance to BCM controlled

CONFERENCE REPORT ANTIRETROVIRAL RESISTANCE

African Journals Online (AJOL)

2004-08-02

Aug 2, 2004 ... development of new agents with potential clinical utility for treating resistant ... data on the emergence of resistance among Thai women given zidovudine ... had achieved full virological suppression (viral load. < 50 copies/ml).

The role of creep in the time-dependent resistance of Ohmic gold contacts in radio frequency microelectromechanical system devices

Science.gov (United States)

Rezvanian, O.; Brown, C.; Zikry, M. A.; Kingon, A. I.; Krim, J.; Irving, D. L.; Brenner, D. W.

2008-07-01

It is shown that measured and calculated time-dependent electrical resistances of closed gold Ohmic switches in radio frequency microelectromechanical system (rf-MEMS) devices are well described by a power law that can be derived from a single asperity creep model. The analysis reveals that the exponent and prefactor in the power law arise, respectively, from the coefficient relating creep rate to applied stress and the initial surface roughness. The analysis also shows that resistance plateaus are not, in fact, limiting resistances but rather result from the small coefficient in the power law. The model predicts that it will take a longer time for the contact resistance to attain a power law relation with each successive closing of the switch due to asperity blunting. Analysis of the first few seconds of the measured resistance for three successive openings and closings of one of the MEMS devices supports this prediction. This work thus provides guidance toward the rational design of Ohmic contacts with enhanced reliabilities by better defining variables that can be controlled through material selection, interface processing, and switch operation.

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.

Reduction of MLH1 and PMS2 confers temozolomide resistance and is associated with recurrence of glioblastoma.

Science.gov (United States)

Shinsato, Yoshinari; Furukawa, Tatsuhiko; Yunoue, Shunji; Yonezawa, Hajime; Minami, Kentarou; Nishizawa, Yukihiko; Ikeda, Ryuji; Kawahara, Kohichi; Yamamoto, Masatatsu; Hirano, Hirofumi; Tokimura, Hiroshi; Arita, Kazunori

2013-12-01

Although there is a relationship between DNA repair deficiency and temozolomide (TMZ) resistance in glioblastoma (GBM), it remains unclear which molecule is associated with GBM recurrence. We isolated three TMZ-resistant human GBM cell lines and examined the expression of O6-methylguanine-DNA methyltransferase (MGMT) and mismatch repair (MMR) components. We used immunohistochemical analysis to compare MutL homolog 1 (MLH1), postmeiotic segregation increased 2 (PMS2) and MGMT expression in primary and recurrent GBM specimens obtained from GBM patients during TMZ treatment. We found a reduction in MLH1 expression and a subsequent reduction in PMS2 protein levels in TMZ-resistant cells. Furthermore, MLH1 or PMS2 knockdown confered TMZ resistance. In recurrent GBM tumours, the expression of MLH1 and PMS2 was reduced when compared to primary tumours.

Molecular and biochemical characterization of an induced mutation conferring imidazolinone resistance in sunflower.

Science.gov (United States)

Sala, Carlos A; Bulos, Mariano; Echarte, Mariel; Whitt, Sherry R; Ascenzi, Robert

2008-12-01

A partially dominant nuclear gene conferring resistance to the imidazolinone herbicides was previously identified in the cultivated sunflower (Helianthus annuus L.) line CLHA-Plus developed by seed mutagenesis. The objective of this study was to characterize this resistant gene at the phenotypic, biochemical and molecular levels. CLHA-Plus showed a complete susceptibility to sulfonylureas (metsulfuron, tribenuron and chlorsulfuron) but, on the other hand, it showed a complete resistance to imidazolinones (imazamox, imazapyr and imazapic) at two rates of herbicide application. This pattern was in close association with the AHAS-inhibition kinetics of protein extracts of CLHA-Plus challenged with different doses of imazamox and chlorsulfuron. Nucleotide and deduced amino acid sequence comparisons between resistant and susceptible lines indicated that the imidazolinone-resistant AHAS of CLHA-Plus has a threonine codon (ACG) at position 122 (relative to the Arabidopsis thaliana AHAS sequence), whereas the herbicide-susceptible enzyme from BTK47 has an alanine residue (GCG) at this position. Since the resistance genes to AHAS-inhibiting herbicides so far characterized in sunflower code for the catalytic (large) subunit of AHAS, we propose to redesignate the wild type allele as ahasl1 and the incomplete dominant resistant alleles as Ahasl1-1 (previously Imr1 or Ar ( pur )), Ahasl1-2 (previously Ar ( kan )) and Ahasl1-3 (for the allele present in CLHA-Plus). The higher tolerance level to imidazolinones and the lack of cross-resistance to other AHAS-inhibiting herbicides of Ahasl1-3 indicate that this induced mutation can be used to develop commercial hybrids with superior levels of tolerance and, at the same time, to assist weed management where control of weedy common sunflower is necessary.

High-resolution mapping reveals linkage between genes in common bean cultivar Ouro Negro conferring resistance to the rust, anthracnose, and angular leaf spot diseases.

Science.gov (United States)

Valentini, Giseli; Gonçalves-Vidigal, Maria Celeste; Hurtado-Gonzales, Oscar P; de Lima Castro, Sandra Aparecida; Cregan, Perry B; Song, Qijian; Pastor-Corrales, Marcial A

2017-08-01

Co-segregation analysis and high-throughput genotyping using SNP, SSR, and KASP markers demonstrated genetic linkage between Ur-14 and Co-3 4 /Phg-3 loci conferring resistance to the rust, anthracnose and angular leaf spot diseases of common bean. Rust, anthracnose, and angular leaf spot are major diseases of common bean in the Americas and Africa. The cultivar Ouro Negro has the Ur-14 gene that confers broad spectrum resistance to rust and the gene cluster Co-3 4 /Phg-3 containing two tightly linked genes conferring resistance to anthracnose and angular leaf spot, respectively. We used co-segregation analysis and high-throughput genotyping of 179 F 2:3 families from the Rudá (susceptible) × Ouro Negro (resistant) cross-phenotyped separately with races of the rust and anthracnose pathogens. The results confirmed that Ur-14 and Co-3 4 /Phg-3 cluster in Ouro Negro conferred resistance to rust and anthracnose, respectively, and that Ur-14 and the Co-3 4 /Phg-3 cluster were closely linked. Genotyping the F 2:3 families, first with 5398 SNPs on the Illumina BeadChip BARCBEAN6K_3 and with 15 SSR, and eight KASP markers, specifically designed for the candidate region containing Ur-14 and Co-3 4 /Phg-3, permitted the creation of a high-resolution genetic linkage map which revealed that Ur-14 was positioned at 2.2 cM from Co-3 4 /Phg-3 on the short arm of chromosome Pv04 of the common bean genome. Five flanking SSR markers were tightly linked at 0.1 and 0.2 cM from Ur-14, and two flanking KASP markers were tightly linked at 0.1 and 0.3 cM from Co-3 4 /Phg-3. Many other SSR, SNP, and KASP markers were also linked to these genes. These markers will be useful for the development of common bean cultivars combining the important Ur-14 and Co-3 4 /Phg-3 genes conferring resistance to three of the most destructive diseases of common bean.

History, contact and classification of Papuan languages, Part I

NARCIS (Netherlands)

Hammarström, Harald; den Heuvel, van Wilco

Harald Hammarström and Wilco van den Heuvel organized a conference on the History, contact, and classification of Papuan languages, and edited this peer-reviewed special issue of the journal Languages and Linguistics in Melanesia following the conference.

ClbS Is a Cyclopropane Hydrolase That Confers Colibactin Resistance.

Science.gov (United States)

Tripathi, Prabhanshu; Shine, Emilee E; Healy, Alan R; Kim, Chung Sub; Herzon, Seth B; Bruner, Steven D; Crawford, Jason M

2017-12-13

Certain commensal Escherichia coli contain the clb biosynthetic gene cluster that codes for small molecule prodrugs known as precolibactins. Precolibactins are converted to colibactins by N-deacylation; the latter are postulated to be genotoxic and to contribute to colorectal cancer formation. Though advances toward elucidating (pre)colibactin biosynthesis have been made, the functions and mechanisms of several clb gene products remain poorly understood. Here we report the 2.1 Å X-ray structure and molecular function of ClbS, a gene product that confers resistance to colibactin toxicity in host bacteria and which has been shown to be important for bacterial viability. The structure harbors a potential colibactin binding site and shares similarity to known hydrolases. In vitro studies using a synthetic colibactin analog and ClbS or an active site residue mutant reveal cyclopropane hydrolase activity that converts the electrophilic cyclopropane of the colibactins into an innocuous hydrolysis product. As the cyclopropane has been shown to be essential for genotoxic effects in vitro, this ClbS-catalyzed ring-opening provides a means for the bacteria to circumvent self-induced genotoxicity. Our study provides a molecular-level view of the first reported cyclopropane hydrolase and support for a specific mechanistic role of this enzyme in colibactin resistance.

The cold-induced defensin TAD1 confers resistance against snow mold and Fusarium head blight in transgenic wheat.

Science.gov (United States)

Sasaki, Kentaro; Kuwabara, Chikako; Umeki, Natsuki; Fujioka, Mari; Saburi, Wataru; Matsui, Hirokazu; Abe, Fumitaka; Imai, Ryozo

2016-06-20

TAD1 (Triticum aestivum defensin 1) is induced during cold acclimation in winter wheat and encodes a plant defensin with antimicrobial activity. In this study, we demonstrated that recombinant TAD1 protein inhibits hyphal growth of the snow mold fungus, Typhula ishikariensis in vitro. Transgenic wheat plants overexpressing TAD1 were created and tested for resistance against T. ishikariensis. Leaf inoculation assays revealed that overexpression of TAD1 confers resistance against the snow mold. In addition, the TAD1-overexpressors showed resistance against Fusarium graminearum, which causes Fusarium head blight, a devastating disease in wheat and barley. These results indicate that TAD1 is a candidate gene to improve resistance against multiple fungal diseases in cereal crops. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultralow contact resistance at an epitaxial metal/oxide heterojunction through interstitial site doping.

Science.gov (United States)

Chambers, Scott A; Gu, Meng; Sushko, Peter V; Yang, Hao; Wang, Chongmin; Browning, Nigel D

2013-08-07

Heteroepitaxial growth of Cr metal on Nb-doped SrTiO₃(001) is accompanied by Cr diffusion to interstitial sites within the first few atomic planes, an anchoring of the Cr film to the substrate, charge transfer from Cr to Ti, and metallization of the near-surface region, as depicted in the figure. The contact resistance of the resulting interface is exceedingly low. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel amino acid substitution Trp574Arg in acetolactate synthase (ALS) confers broad resistance to ALS-inhibiting herbicides in crabgrass (Digitaria sanguinalis).

Science.gov (United States)

Li, Jian; Li, Mei; Gao, Xingxiang; Fang, Feng

2017-12-01

Crabgrass (Digitaria sanguinalis) is an annual monocotyledonous weed. In recent years, field applications of nicosulfuron have been ineffective in controlling crabgrass populations in Shandong Province, China. To investigate the mechanisms of resistance to nicosulfuron in crabgrass populations, the acetolactate synthase (ALS) gene fragment covering known resistance-confering mutation sites was amplified and sequenced. Dose-response experiments suggested that the resistant population SD13 (R) was highly resistant to nicosulfuron (resistance index R/S = 43.7) compared with the sensitive population SD22 (S). ALS gene sequencing revealed a Trp574Arg substitution in the SD13 population, and no other known resistance-conferring mutations were found. In vitro ALS enzyme assays further confirmed that the SD13 population was resistant to all tested ALS-inhibiting herbicides. The resistance pattern experiments revealed that, compared with SD22, the SD13 population exhibited broad-spectrum resistance to nicosulfuron (43.7-fold), imazethapyr (11.4-fold) and flumetsulam (16.1-fold); however, it did not develop resistance to atrazine, mesotrione and topramezone. This study demonstrated that Trp574Arg substitution was the main reason for crabgrass resistance to ALS-inhibiting herbicides. To our knowledge, this is the first report of Trp574Arg substitution in a weed species, and is the first report of target-site mechanisms of herbicide resistance for crabgrass. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

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

in phase transformation of the steel and in formation of oxides with a poor electrical conductivity in the anode. In this study, the area specific resistance (ASR) of the steel Crofer 22 APU, in contact with a Ni/YSZ anode with and without a tape casted CeO2 barrier layer was measured in simulated SOFC...... 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...

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.

Evaluation of pet contact as a risk factor for carriage of multidrug-resistant staphylococci in nursing home residents.

Science.gov (United States)

Gandolfi-Decristophoris, Paola; De Benedetti, Anna; Petignat, Christiane; Attinger, Monica; Guillaume, Jan; Fiebig, Lena; Hattendorf, Jan; Cernela, Nicole; Regula, Gertraud; Petrini, Orlando; Zinsstag, Jakob; Schelling, Esther

2012-03-01

Pets, often used as companionship and for psychological support in the therapy of nursing home residents, have been implicated as reservoirs for antibiotic-resistant bacteria. We investigated the importance of pets as reservoirs of multidrug-resistant (MDR) staphylococci in nursing homes. We assessed the carriage of MDR staphylococci in pets and in 2 groups of residents, those living in nursing homes with pets and those living without pet contacts. We collected demographic, health status, and human-pet contact data by means of questionnaires. We assessed potential bacteria transmission pathways by investigating physical resident-to-pet contact. The observed prevalence of MDR staphylococci carriage was 84/229 (37%) in residents living with pets and 99/216 (46%) in those not living with pets (adjusted odds ratio [aOR], 0.6; 95% confidence interval [CI], 0.4-0.9). Active pet contact was associated with lower carriage of MDR staphylococci (aOR, 0.5; 95% CI, 0.4-0.8). Antibiotic treatment during the previous 3 months was associated with significantly increased risk for MDR carriage in residents (aOR, 3.1; 95% CI, 1.8-5.7). We found no evidence that the previously reported benefits of pet contact are compromised by the increased risk of carriage of MDR staphylococci in residents associated with interaction with these animals in nursing homes. Thus, contact with pets, always under good hygiene standards, should be encouraged in these settings. Copyright © 2012 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

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.

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.

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.

Thermographic Inspection of Fatigue Crack by Using Contact Thermal Resistance

Energy Technology Data Exchange (ETDEWEB)

Yang, Seung Yong; Kim, No Hyu [Korean University of Technology and Education, Cheonan (Korea, Republic of)

2013-04-15

Fatigue crack was detected from a temperature change around surface crack using the thermographic technique. Thermal gradient across the crack decreased very much due to thermal resistance of contact surface in the crack. Heat diffusion flow passing through the discontinuity was visualized in temperature by infrared camera to find and locate the crack. A fatigue crack specimen(SM-45C), which was prepared according to KS specification and notched in its center to initiate fatigue crack from the notch tip, was heated by halogen lamp at the end of one side to generate a heat diffusion flow in lateral direction. A abrupt jump in temperature across the fatigue crack was observed in thermographic image, by which the crack could be located and sized from temperature distribution.

Thermographic Inspection of Fatigue Crack by Using Contact Thermal Resistance

International Nuclear Information System (INIS)

Yang, Seung Yong; Kim, No Hyu

2013-01-01

Fatigue crack was detected from a temperature change around surface crack using the thermographic technique. Thermal gradient across the crack decreased very much due to thermal resistance of contact surface in the crack. Heat diffusion flow passing through the discontinuity was visualized in temperature by infrared camera to find and locate the crack. A fatigue crack specimen(SM-45C), which was prepared according to KS specification and notched in its center to initiate fatigue crack from the notch tip, was heated by halogen lamp at the end of one side to generate a heat diffusion flow in lateral direction. A abrupt jump in temperature across the fatigue crack was observed in thermographic image, by which the crack could be located and sized from temperature distribution.

Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death.

Science.gov (United States)

Narayanan, Kannan Badri; Ali, Manaf; Barclay, Barry J; Cheng, Qiang Shawn; D'Abronzo, Leandro; Dornetshuber-Fleiss, Rita; Ghosh, Paramita M; Gonzalez Guzman, Michael J; Lee, Tae-Jin; Leung, Po Sing; Li, Lin; Luanpitpong, Suidjit; Ratovitski, Edward; Rojanasakul, Yon; Romano, Maria Fiammetta; Romano, Simona; Sinha, Ranjeet K; Yedjou, Clement; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Brown, Dustin G; Ryan, Elizabeth P; Colacci, Annamaria; Hamid, Roslida A; Mondello, Chiara; Raju, Jayadev; Salem, Hosni K; Woodrick, Jordan; Scovassi, A Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Kim, Seo Yun; Bisson, William H; Lowe, Leroy; Park, Hyun Ho

2015-06-01

Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototypical chemical disruptors; as their effects relate to resistance to cell death, as constituents within environmental mixtures and as potential contributors to environmental carcinogenesis. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Alcohol dehydrogenase 1 (ADH1) confers both abiotic and biotic stress resistance in Arabidopsis.

Science.gov (United States)

Shi, Haitao; Liu, Wen; Yao, Yue; Wei, Yunxie; Chan, Zhulong

2017-09-01

Although the transcriptional regulation and upstream transcription factors of AtADH1 in response to abiotic stress are widely revealed, the in vivo roles of AtADH1 remain unknown. In this study, we found that the expression of AtADH1 was largely induced after salt, drought, cold and pathogen infection. Further studies found that AtADH1 overexpressing plants were more sensitive to abscisic acid (ABA) in comparison to wide type (WT), while AtADH1 knockout mutants showed no significant difference compared with WT in ABA sensitivity. Consistently, AtADH1 overexpressing plants showed improved stress resistance to salt, drought, cold and pathogen infection than WT, but the AtADH1 knockout mutants had no significant difference in abiotic and biotic stress resistance. Moreover, overexpression of AtADH1 expression increased the transcript levels of multiple stress-related genes, accumulation of soluble sugars and callose depositions. All these results indicate that AtADH1 confers enhanced resistance to both abiotic and biotic stresses. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

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.

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

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...

A Gene Homologous to rRNA Methylase Genes Confers Erythromycin and Clindamycin Resistance in Bifidobacterium breve.

Science.gov (United States)

Martínez, Noelia; Luque, Roberto; Milani, Christian; Ventura, Marco; Bañuelos, Oscar; Margolles, Abelardo

2018-05-15

Bifidobacteria are mutualistic intestinal bacteria, and their presence in the human gut has been associated with health-promoting activities. The presence of antibiotic resistance genes in this genus is controversial, since, although bifidobacteria are nonpathogenic microorganisms, they could serve as reservoirs of resistance determinants for intestinal pathogens. However, until now, few antibiotic resistance determinants have been functionally characterized in this genus. In this work, we show that Bifidobacterium breve CECT7263 displays atypical resistance to erythromycin and clindamycin. In order to delimit the genomic region responsible for the observed resistance phenotype, a library of genomic DNA was constructed and a fragment of 5.8 kb containing a gene homologous to rRNA methylase genes was able to confer erythromycin resistance in Escherichia coli This genomic region seems to be very uncommon, and homologs of the gene have been detected in only one strain of Bifidobacterium longum and two other strains of B. breve In this context, analysis of shotgun metagenomics data sets revealed that the gene is also uncommon in the microbiomes of adults and infants. The structural gene and its upstream region were cloned into a B. breve -sensitive strain, which became resistant after acquiring the genetic material. In vitro conjugation experiments did not allow us to detect gene transfer to other recipients. Nevertheless, prediction of genes potentially acquired through horizontal gene transfer events revealed that the gene is located in a putative genomic island. IMPORTANCE Bifidobacterium breve is a very common human intestinal bacterium. Often described as a pioneer microorganism in the establishment of early-life intestinal microbiota, its presence has been associated with several beneficial effects for the host, including immune stimulation and protection against infections. Therefore, some strains of this species are considered probiotics. In relation to this

Protein-protein association and cellular localization of four essential gene products encoded by tellurite resistance-conferring cluster "ter" from pathogenic Escherichia coli.

Science.gov (United States)

Valkovicova, Lenka; Vavrova, Silvia Minarikova; Mravec, Jozef; Grones, Jozef; Turna, Jan

2013-12-01

Gene cluster "ter" conferring high tellurite resistance has been identified in various pathogenic bacteria including Escherichia coli O157:H7. However, the precise mechanism as well as the molecular function of the respective gene products is unclear. Here we describe protein-protein association and localization analyses of four essential Ter proteins encoded by minimal resistance-conferring fragment (terBCDE) by means of recombinant expression. By using a two-plasmid complementation system we show that the overproduced single Ter proteins are not able to mediate tellurite resistance, but all Ter members play an irreplaceable role within the cluster. We identified several types of homotypic and heterotypic protein-protein associations among the Ter proteins by in vitro and in vivo pull-down assays and determined their cellular localization by cytosol/membrane fractionation. Our results strongly suggest that Ter proteins function involves their mutual association, which probably happens at the interface of the inner plasma membrane and the cytosol.

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.

Haemophilus parasuis CpxRA two-component system confers bacterial tolerance to environmental stresses and macrolide resistance.

Science.gov (United States)

Cao, Qi; Feng, Fenfen; Wang, Huan; Xu, Xiaojuan; Chen, Huanchun; Cai, Xuwang; Wang, Xiangru

2018-01-01

Haemophilus parasuis is an opportunistic pathogen localized in the upper respiratory tracts of pigs, its infection begins from bacterial survival under complex conditions, like hyperosmosis, oxidative stress, phagocytosis, and sometimes antibiotics as well. The two-component signal transduction (TCST) system serves as a common stimulus-response mechanism that allows microbes to sense and respond to diverse environmental conditions via a series of phosphorylation reactions. In this study, we investigated the role of TCST system CpxRA in H. parasuis in response to different environmental stimuli by constructing the ΔcpxA and ΔcpxR single deletion mutants as well as the ΔcpxRA double deletion mutant from H. parasuis serotype 4 isolate JS0135. We demonstrated that H. parasuis TCST system CpxRA confers bacterial tolerance to stresses and bactericidal antibiotics. The CpxR was found to play essential roles in mediating oxidative stress, osmotic stresses and alkaline pH stress tolerance, as well as macrolide resistance (i.e. erythromycin), but the CpxA deletion did not decrease bacterial resistance to abovementioned stresses. Moreover, we found via RT-qPCR approach that HAPS_RS00160 and HAPS_RS09425, both encoding multidrug efflux pumps, were significantly decreased in erythromycin challenged ΔcpxR and ΔcpxRA mutants compared with wild-type strain JS0135. These findings characterize the role of the TCST system CpxRA in H. parasuis conferring stress response tolerance and bactericidal resistance, which will deepen our understanding of the pathogenic mechanism in H. parasuis. Copyright © 2017 Elsevier GmbH. All rights reserved.

Physical Localization of a Locus from Agropyron cristatum Conferring Resistance to Stripe Rust in Common Wheat.

Science.gov (United States)

Zhang, Zhi; Song, Liqiang; Han, Haiming; Zhou, Shenghui; Zhang, Jinpeng; Yang, Xinming; Li, Xiuquan; Liu, Weihua; Li, Lihui

2017-11-13

Stripe rust, caused by Puccinia striiformis f. sp. tritici ( Pst ), is one of the most destructive diseases of wheat ( Triticum aestivum L.) worldwide. Agropyron cristatum (L.) Gaertn. (2 n = 28, PPPP), one of the wild relatives of wheat, exhibits resistance to stripe rust. In this study, wheat- A . cristatum 6P disomic addition line 4844-12 also exhibited resistance to stripe rust. To identify the stripe rust resistance locus from A . cristatum 6P, ten translocation lines, five deletion lines and the BC₂F₂ and BC₃F₂ populations of two wheat- A . cristatum 6P whole-arm translocation lines were tested with a mixture of two races of Pst in two sites during 2015-2016 and 2016-2017, being genotyped with genomic in situ hybridization (GISH) and molecular markers. The result indicated that the locus conferring stripe rust resistance was located on the terminal 20% of 6P short arm's length. Twenty-nine 6P-specific sequence-tagged-site (STS) markers mapped on the resistance locus have been acquired, which will be helpful for the fine mapping of the stripe rust resistance locus. The stripe rust-resistant translocation lines were found to carry some favorable agronomic traits, which could facilitate their use in wheat improvement. Collectively, the stripe rust resistance locus from A . cristatum 6P could be a novel resistance source and the screened stripe rust-resistant materials will be valuable for wheat disease breeding.

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).

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.

Academic Conferences: Representative and Resistant Sites for Higher Education Research

Science.gov (United States)

Henderson, Emily F.

2015-01-01

The overarching argument made in this article is twofold. Firstly, academic conferences are posited as sites for higher education research. Secondly, the well-recognised emotional and social processes of conferences are used to make space at the boundaries of higher education research for psychosocial analysis. The article theorises conferences in…

Target-site mutations conferring resistance to glyphosate in feathertop Rhodes grass (Chloris virgata) populations in Australia.

Science.gov (United States)

Ngo, The D; Krishnan, Mahima; Boutsalis, Peter; Gill, Gurjeet; Preston, Christopher

2018-05-01

Chloris virgata is a warm-season, C 4 , annual grass weed affecting field crops in northern Australia that has become an emerging weed in southern Australia. Four populations with suspected resistance to glyphosate were collected in South Australia, Queensland and New South Wales, Australia, and compared with one susceptible (S) population to confirm glyphosate resistance and elucidate possible mechanisms of resistance. Based on the rate of glyphosate required to kill 50% of treated plants (LD 50 ), glyphosate resistance (GR) was confirmed in four populations of C. virgata (V12, V14.2, V14.16 and V15). GR plants were 2-9.7-fold more resistant and accumulated less shikimate after glyphosate treatment than S plants. GR and S plants did not differ in glyphosate absorption and translocation. Target-site EPSPS mutations corresponding to Pro-106-Leu (V14.2) and Pro-106-Ser (V15, V14.16 and V12) substitutions were found in GR populations. The population with Pro-106-Leu substitution was 2.9-4.9-fold more resistant than the three other populations with Pro-106-Ser substitution. This report confirms glyphosate resistance in C. virgata and shows that target-site EPSPS mutations confer resistance to glyphosate in this species. The evolution of glyphosate resistance in C. virgata highlights the need to identify alternative control tactics. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Toward High Carrier Mobility and Low Contact Resistance:Laser Cleaning of PMMA Residues on Graphene Surfaces

Institute of Scientific and Technical Information of China (English)

Yuehui Jia; Xin Gong; Pei Peng; Zidong Wang; Zhongzheng Tian; Liming Ren; Yunyi Fu; Han Zhang

2016-01-01

Poly(methyl methacrylate)(PMMA) is widely used for graphene transfer and device fabrication.However,it inevitably leaves a thin layer of polymer residues after acetone rinsing and leads to dramatic degradation of device performance.How to eliminate contamination and restore clean surfaces of graphene is still highly demanded.In this paper,we present a reliable and position-controllable method to remove the polymer residues on graphene films by laser exposure.Under proper laser conditions,PMMA residues can be substantially reduced without introducing defects to the underlying graphene.Furthermore,by applying this laser cleaning technique to the channel and contacts of graphene fieldeffect transistors(GFETs),higher carrier mobility as well as lower contact resistance can be realized.This work opens a way for probing intrinsic properties of contaminant-free graphene and fabricating high-performance GFETs with both clean channel and intimate graphene/metal contact.

A novel blast resistance gene, Pi54rh cloned from wild species of rice, Oryza rhizomatis confers broad spectrum resistance to Magnaporthe oryzae.

Science.gov (United States)

Das, Alok; Soubam, D; Singh, P K; Thakur, S; Singh, N K; Sharma, T R

2012-06-01

The dominant rice blast resistance gene, Pi54 confers resistance to Magnaporthe oryzae in different parts of India. In our effort to identify more effective forms of this gene, we isolated an orthologue of Pi54 named as Pi54rh from the blast-resistant wild species of rice, Oryza rhizomatis, using allele mining approach and validated by complementation. The Pi54rh belongs to CC-NBS-LRR family of disease resistance genes with a unique Zinc finger (C(3)H type) domain. The 1,447 bp Pi54rh transcript comprises of 101 bp 5'-UTR, 1,083 bp coding region and 263 bp 3'-UTR, driven by pathogen inducible promoter. We showed the extracellular localization of Pi54rh protein and the presence of glycosylation, myristoylation and phosphorylation sites which implicates its role in signal transduction process. This is in contrast to other blast resistance genes that are predicted to be intracellular NBS-LRR-type resistance proteins. The Pi54rh was found to express constitutively at basal level in the leaves, but upregulates 3.8-fold at 96 h post-inoculation with the pathogen. Functional validation of cloned Pi54rh gene using complementation test showed high degree of resistance to seven isolates of M. oryzae collected from different geographical locations of India. In this study, for the first time, we demonstrated that a rice blast resistance gene Pi54rh cloned from wild species of rice provides broad spectrum resistance to M. oryzae hence can be used in rice improvement breeding programme.

Contact resistance measurement structures for high frequencies

NARCIS (Netherlands)

Roy, Deepu; Pijper, Ralf M.T.; Tiemeijer, Luuk F.; Wolters, Robertus A.M.

2011-01-01

Knowledge of the interfacial contact impedance offered by the device at its operating frequency range is crucial for accurate modelling and understanding of the device. In this article, a novel modified TLM test-structure has been devised to extract interfacial contact parameters at frequencies upto

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

KAUST Repository

Sun, Jian; Kosel, Jü rgen

2011-01-01

.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

Experimental Characterization and Modeling of Thermal Contact Resistance of Electric Machine Stator-to-Cooling Jacket Interface Under Interference Fit Loading

Energy Technology Data Exchange (ETDEWEB)

Cousineau, Justine E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bennion, Kevin S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chieduko, Victor [UQM Technologies, Inc.; Lall, Rajiv [UQM Technologies, Inc.; Gilbert, Alan [UQM Technologies, Inc.

2018-05-08

Cooling of electric machines is a key to increasing power density and improving reliability. This paper focuses on the design of a machine using a cooling jacket wrapped around the stator. The thermal contact resistance (TCR) between the electric machine stator and cooling jacket is a significant factor in overall performance and is not well characterized. This interface is typically an interference fit subject to compressive pressure exceeding 5 MPa. An experimental investigation of this interface was carried out using a thermal transmittance setup using pressures between 5 and 10 MPa. The results were compared to currently available models for contact resistance, and one model was adapted for prediction of TCR in future motor designs.

Degradation pattern of black phosphorus multilayer field-effect transistors in ambient conditions: Strategy for contact resistance engineering in BP transistors

Science.gov (United States)

Lee, Byung Chul; Kim, Chul Min; Jang, Ho-Kyun; Lee, Jae Woo; Joo, Min-Kyu; Kim, Gyu-Tae

2017-10-01

Black phosphorus (BP) has been proposed as a future optoelectronic material owing to its direct bandgap with excellent electrical performances. However, oxygen (O2) and water (H2O) molecules in an ambient condition can create undesired bubbles on the surface of the BP, resulting in hampering its excellent intrinsic properties. Here, we report the electrical degradation pattern of a mechanically exfoliated BP field-effect transistor (FET) in terms of the channel and contact, separately. Various electrical parameters such as the threshold voltage (VTH), carrier mobility (μ), contact resistance (RCT) and channel resistance (RCH) are estimated by the Y function method (YFM) with respect to time (up to 2000 min). It is found that RCT reduces and then, increases with time; whereas, the behavior of RCH is vice versa in ambient conditions. We attribute these effects to oxygen doping at the contact and the surface oxidation effects on the surface of the BP, respectively.

Inheritance of resistance to watermelon mosaic virus in the cucumber line TMG-1: tissue-specific expression and relationship to zucchini yellow mosaic virus resistance.

Science.gov (United States)

Wai, T; Grumet, R

1995-09-01

The inbred cucumber (Cucumis sativus L.) line TMG-1 is resistant to three potyviruses:zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV), and the watermelon strain of papaya ringspot virus (PRSV-W). The genetics of resistance to WMV and the relationship of WMV resistance to ZYMV resistance were examined. TMG-1 was crossed with WI-2757, a susceptible inbred line. F1, F2 and backcross progeny populations were screened for resistance to WMV and/or ZYMV. Two independently assorting factors conferred resistance to WMV. One resistance was conferred by a single recessive gene from TMG-1 (wmv-2). The second resistance was conferred by an epistatic interaction between a second recessive gene from TMG-1 (wmv-3) and either a dominant gene from WI-2757 (Wmv-4) or a third recessive gene from TMG-1 (wmv-4) located 20-30 cM from wmv-3. The two resistances exhibited tissue-specific expression. Resistance conferred by wmv-2 was expressed in the cotyledons and throughout the plant. Resistance conferred by wmv-3 + Wmv-4 (or wmv-4) was expressed only in true leaves. The gene conferring resistance to ZYMV appeared to be the same as, or tightly linked to one of the WMV resistance genes, wmv-3.

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

Mapping a Quantitative Trait Locus (QTL conferring pyrethroid resistance in the African malaria vector Anopheles funestus

Directory of Open Access Journals (Sweden)

Hunt Richard H

2007-01-01

Full Text Available Abstract Background Pyrethroid resistance in Anopheles funestus populations has led to an increase in malaria transmission in southern Africa. Resistance has been attributed to elevated activities of cytochrome P450s but the molecular basis underlying this metabolic resistance is unknown. Microsatellite and SNP markers were used to construct a linkage map and to detect a quantitative trait locus (QTL associated with pyrethroid resistance in the FUMOZ-R strain of An. funestus from Mozambique. Results By genotyping 349 F2 individuals from 11 independent families, a single major QTL, rp1, at the telomeric end of chromosome 2R was identified. The rp1 QTL appears to present a major effect since it accounts for more than 60% of the variance in susceptibility to permethrin. This QTL has a strong additive genetic effect with respect to susceptibility. Candidate genes associated with pyrethroid resistance in other species were physically mapped to An. funestus polytene chromosomes. This showed that rp1 is genetically linked to a cluster of CYP6 cytochrome P450 genes located on division 9 of chromosome 2R and confirmed earlier reports that pyrethroid resistance in this strain is not associated with target site mutations (knockdown resistance. Conclusion We hypothesize that one or more of these CYP6 P450s clustered on chromosome 2R confers pyrethroid resistance in the FUMOZ-R strain of An. funestus.

Transgenic expression of the rice Xa21 pattern-recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum.

Science.gov (United States)

Tripathi, Jaindra N; Lorenzen, Jim; Bahar, Ofir; Ronald, Pamela; Tripathi, Leena

2014-08-01

Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21-mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar 'Gonja manjaya' (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Low p-type contact resistance by field-emission tunneling in highly Mg-doped GaN

Science.gov (United States)

Okumura, Hironori; Martin, Denis; Grandjean, Nicolas

2016-12-01

Mg-doped GaN with a net acceptor concentration (NA-ND) in the high 1019 cm-3 range was grown using ammonia molecular-beam epitaxy. Electrical properties of NiO contact on this heavily doped p-type GaN were investigated. A potential-barrier height of 0.24 eV was extracted from the relationship between NA-ND and the specific contact resistivity (ρc). We found that there is an optimum NA-ND value of 5 × 1019 cm-3 for which ρc is as low as 2 × 10-5 Ω cm2. This low ρc is ascribed to hole tunneling through the potential barrier at the NiO/p+-GaN interface, which is well accounted for by the field-emission model.

TaPP2C1, a Group F2 Protein Phosphatase 2C Gene, Confers Resistance to Salt Stress in Transgenic Tobacco.

Directory of Open Access Journals (Sweden)

Wei Hu

Full Text Available Group A protein phosphatases 2Cs (PP2Cs are essential components of abscisic acid (ABA signaling in Arabidopsis; however, the function of group F2 subfamily PP2Cs is currently less known. In this study, TaPP2C1 which belongs to group F2 was isolated and characterized from wheat. Expression of the TaPP2C1-GFP fusion protein suggested its ubiquitous localization within a cell. TaPP2C1 expression was downregulated by abscisic acid (ABA and NaCl treatments, but upregulated by H2O2 treatment. Overexpression of TaPP2C1 in tobacco resulted in reduced ABA sensitivity and increased salt resistance of transgenic seedlings. Additionally, physiological analyses showed that improved resistance to salt stress conferred by TaPP2C1 is due to the reduced reactive oxygen species (ROS accumulation, the improved antioxidant system, and the increased transcription of genes in the ABA-independent pathway. Finally, transgenic tobacco showed increased resistance to oxidative stress by maintaining a more effective antioxidant system. Taken together, these results demonstrated that TaPP2C1 negatively regulates ABA signaling, but positively regulates salt resistance. TaPP2C1 confers salt resistance through activating the antioxidant system and ABA-independent gene transcription process.

Contact effects analyzed by a parameter extraction method based on a single bottom-gate/top-contact organic thin-film transistor

Science.gov (United States)

Takagaki, Shunsuke; Yamada, Hirofumi; Noda, Kei

2018-03-01

Contact effects in organic thin-film transistors (OTFTs) were examined by using our previously proposed parameter extraction method from the electrical characteristics of a single staggered-type device. Gate-voltage-dependent contact resistance and channel mobility in the linear regime were evaluated for bottom-gate/top-contact (BGTC) pentacene TFTs with active layers of different thicknesses, and for pentacene TFTs with contact-doped layers prepared by coevaporation of pentacene and tetrafluorotetracyanoquinodimethane (F4TCNQ). The extracted parameters suggested that the influence of the contact resistance becomes more prominent with the larger active-layer thickness, and that contact-doping experiments give rise to a drastic decrease in the contact resistance and a concurrent considerable improvement in the channel mobility. Additionally, the estimated energy distributions of trap density in the transistor channel probably reflect the trap filling with charge carriers injected into the channel regions. The analysis results in this study confirm the effectiveness of our proposed method, with which we can investigate contact effects and circumvent the influences of characteristic variations in OTFT fabrication.

An antibody that confers plant disease resistance targets a membrane-bound glyoxal oxidase in Fusarium.

Science.gov (United States)

Song, Xiu-Shi; Xing, Shu; Li, He-Ping; Zhang, Jing-Bo; Qu, Bo; Jiang, Jin-He; Fan, Chao; Yang, Peng; Liu, Jin-Long; Hu, Zu-Quan; Xue, Sheng; Liao, Yu-Cai

2016-05-01

Plant germplasm resources with natural resistance against globally important toxigenic Fusarium are inadequate. CWP2, a Fusarium genus-specific antibody, confers durable resistance to different Fusarium pathogens that infect cereals and other crops, producing mycotoxins. However, the nature of the CWP2 target is not known. Thus, investigation of the gene coding for the CWP2 antibody target will likely provide critical insights into the mechanism underlying the resistance mediated by this disease-resistance antibody. Immunoblots and mass spectrometry analysis of two-dimensional electrophoresis gels containing cell wall proteins from Fusarium graminearum (Fg) revealed that a glyoxal oxidase (GLX) is the CWP2 antigen. Cellular localization studies showed that GLX is localized to the plasma membrane. This GLX efficiently catalyzes hydrogen peroxide production; this enzymatic activity was specifically inhibited by the CWP2 antibody. GLX-deletion strains of Fg, F. verticillioides (Fv) and F. oxysporum had significantly reduced virulence on plants. The GLX-deletion Fg and Fv strains had markedly reduced mycotoxin accumulation, and the expression of key genes in mycotoxin metabolism was downregulated. This study reveals a single gene-encoded and highly conserved cellular surface antigen that is specifically recognized by the disease-resistance antibody CWP2 and regulates both virulence and mycotoxin biosynthesis in Fusarium species. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Flexible textile-based strain sensor induced by contacts

International Nuclear Information System (INIS)

Zhang, Hui

2015-01-01

In this paper, the contact effects are used as the key sensing element to develop flexible textile-structured strain sensors. The structures of the contact are analyzed theoretically and the contact resistances are investigated experimentally. The electromechanical properties of the textiles are investigated to find the key factors which determine the sensitivity, repeatability, and linearity of the sensor. The sensing mechanism is based on the change of contact resistance induced by the change of the configuration of the textiles. In order to improve the performance of the textile strain sensor, the contact resistance is designed based on the electromechanical properties of the fabric. It can be seen from the results that the performance of the sensor is largely affected by the structure of the contacts, which are determined by the morphology of fiber surface and the structures of the yarn and fabric. (paper)

Effect of thermal contact resistances on fast charging of large format lithium ion batteries

International Nuclear Information System (INIS)

Ye, Yonghuang; Saw, Lip Huat; Shi, Yixiang; Somasundaram, Karthik; Tay, Andrew A.O.

2014-01-01

Highlights: • The effect of thermal contact resistance on thermal performance of large format lithium ion batteries. • The effect of temperature gradient on electrochemical performance of large format batteries during fast charging. • The thermal performance of lithium ion battery utilizing pulse charging protocol. • Suggestions on battery geometry design optimization to improve thermal performance. - Abstract: A two dimensional electrochemical thermal model is developed on the cross-plane of a laminate stack plate pouch lithium ion battery to study the thermal performance of large format batteries. The effect of thermal contact resistance is taken into consideration, and is found to greatly increase the maximum temperature and temperature gradient of the battery. The resulting large temperature gradient would induce in-cell non-uniformity of charging-discharging current and state of health. Simply increasing the cooling intensity is inadequate to reduce the maximum temperature and narrow down the temperature difference due to the poor cross-plane thermal conductivity. Pulse charging protocol does not help to mitigate the temperature difference on the bias of same total charging time, because of larger time-averaged heat generation rate than constant current charging. Suggestions on battery geometry optimizations for both prismatic/pouch battery and cylindrical battery are proposed to reduce the maximum temperature and mitigate the temperature gradient within the lithium ion battery

Obesogenic memory can confer long-term increases in adipose tissue but not liver inflammation and insulin resistance after weight loss

Directory of Open Access Journals (Sweden)

J. Schmitz

2016-05-01

Conclusions: These results demonstrate that although sustained weight loss improves systemic glucose homeostasis, primarily through improved inflammation and insulin action in liver, a remarkable obesogenic memory can confer long-term increases in adipose tissue inflammation and insulin resistance in mice as well as in a significant subpopulation of obese patients.

Voltage-sensitive sodium channel mutations S989P + V1016G in Aedes aegypti confer variable resistance to pyrethroids, DDT and oxadiazines.

Science.gov (United States)

Smith, Letícia B; Kasai, Shinji; Scott, Jeffrey G

2018-03-01

Aedes aegypti is a vector of several important human pathogens. Control efforts rely primarily on pyrethroid insecticides for adult mosquito control, especially during disease outbreaks. A. aegypti has developed resistance nearly everywhere it occurs and insecticides are used. An important mechanism of resistance is due to mutations in the voltage-sensitive sodium channel (Vssc) gene. Two mutations, in particular, S989P + V1016G, commonly occur together in parts of Asia. We have created a strain (KDR:ROCK) that contains the Vssc mutations S989P + V1016G as the only mechanism of pyrethroid resistance within the genetic background of Rockefeller (ROCK), a susceptible lab strain. We created KDR:ROCK by crossing the pyrethroid-resistant strain Singapore with ROCK followed by four backcrosses with ROCK and Vssc S989P + V1016G genotype selections. We determined the levels of resistance conferred to 17 structurally diverse pyrethroids, the organochloride DDT, and oxadiazines (VSSC blockers) indoxacarb (proinsecticide) and DCJW (the active metabolite of indoxacarb). Levels of resistance to the pyrethroids were variable, ranging from 21- to 107-fold, but no clear pattern between resistance and chemical structure was observed. Resistance is inherited as an incompletely recessive trait. KDR:ROCK had a > 2000-fold resistance to DDT, 37.5-fold cross-resistance to indoxacarb and 13.4-fold cross-resistance to DCJW. Etofenprox (and DDT) should be avoided in areas where Vssc mutations S989P + V1016G exist at high frequencies. We found that pyrethroid structure cannot be used to predict the level of resistance conferred by kdr. These results provide useful information for resistance management and for better understanding pyrethroid interactions with VSSC. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of

Identification of 8-methyladenosine as the modification catalyzed by the radical SAM methyltransferase Cfr that confers antibiotic resistance in bacteria

DEFF Research Database (Denmark)

Giessing, Anders; Jensen, Søren Skov; Rasmussen, Anette

2009-01-01

The Cfr methyltransferase confers combined resistance to five different classes of antibiotics that bind to the peptidyl transferase center of bacterial ribosomes. The Cfr-mediated modification has previously been shown to occur on nucleotide A2503 of 23S rRNA and has a mass corresponding......,8-dimethyladenosine. The mutation of single conserved cysteine residues in the radical SAM motif CxxxCxxC of Cfr abolishes its activity, lending support to the notion that the Cfr modification reaction occurs via a radical-based mechanism. Antibiotic susceptibility data confirm that the antibiotic resistance...

Influence of Compaction During Reaction Heat Treatment on the Interstrand Contact Resistances of Nb3Sn Rutherford Cables

NARCIS (Netherlands)

Collings, E.W.; Sumption, Mike D.; Majoros, Milan; Wang, Xiaorong; Dietderich, Daniel R.; Yagotyntsev, K.; Nijhuis, Arend

2018-01-01

The amplitudes of multipoles in the bore fields of dipole and quadrupole magnets, induced by ramp-rate-dependent coupling currents, are under the control of the interstrand contact resistances - crossing-strand, Rc, adjacent strand, Ra, or a combination of them, Reff. Although two decades ago it was

Experimental evolution, genetic analysis and genome re-sequencing reveal the mutation conferring artemisinin resistance in an isogenic lineage of malaria parasites

KAUST Repository

Hunt, Paul

2010-09-16

Background: Classical and quantitative linkage analyses of genetic crosses have traditionally been used to map genes of interest, such as those conferring chloroquine or quinine resistance in malaria parasites. Next-generation sequencing technologies now present the possibility of determining genome-wide genetic variation at single base-pair resolution. Here, we combine in vivo experimental evolution, a rapid genetic strategy and whole genome re-sequencing to identify the precise genetic basis of artemisinin resistance in a lineage of the rodent malaria parasite, Plasmodium chabaudi. Such genetic markers will further the investigation of resistance and its control in natural infections of the human malaria, P. falciparum.Results: A lineage of isogenic in vivo drug-selected mutant P. chabaudi parasites was investigated. By measuring the artemisinin responses of these clones, the appearance of an in vivo artemisinin resistance phenotype within the lineage was defined. The underlying genetic locus was mapped to a region of chromosome 2 by Linkage Group Selection in two different genetic crosses. Whole-genome deep coverage short-read re-sequencing (IlluminaSolexa) defined the point mutations, insertions, deletions and copy-number variations arising in the lineage. Eight point mutations arise within the mutant lineage, only one of which appears on chromosome 2. This missense mutation arises contemporaneously with artemisinin resistance and maps to a gene encoding a de-ubiquitinating enzyme.Conclusions: This integrated approach facilitates the rapid identification of mutations conferring selectable phenotypes, without prior knowledge of biological and molecular mechanisms. For malaria, this model can identify candidate genes before resistant parasites are commonly observed in natural human malaria populations. 2010 Hunt et al; licensee BioMed Central Ltd.

Why Conferences Matter—An Illustration from the International Marine Conservation Congress

Directory of Open Access Journals (Sweden)

Samantha Oester

2017-08-01

Full Text Available A major activity in the life of an academic is the professional conference. It is common knowledge that this is a place to present your research, but what about other benefits of attending a conference? Online surveys were distributed to delegates of the 3rd and 4th International Marine Conservation Congresses (IMCCs, with respondents' (n = 100 feedback including that the congresses provided useful new information that will aid: (1 their research (58%; (2 in-the-field conservation (29%; (3 conservation communication (46%; and (4 conservation and management policy making (45%. They also reported gaining new techniques (56%, skills (64%, and novel ideas (70% to further their research/careers. Nearly all (91% gained new contacts that improved their research, in-the-field conservation, science communication, and/or conservation policy making. Two thirds (64% gained ideas, contacts, and/or lessons could lead to publications. Over a third (39% gained new ideas, contacts and/or lessons that led to grant proposals, and 36% gained contacts that led to funding. A conference is not just an avenue for a scientist to present their research to the wider community, but it can be an important venue for brainstorming, networking and making vital connections that can lead to new initiatives, papers and funding, in a way that virtual, online meetings cannot. This is why conferences matter.

Identification of regulated genes conferring resistance to high concentrations of glyphosate in a new strain of Enterobacter.

Science.gov (United States)

Fei, Yun-Yan; Gai, Jun-Yi; Zhao, Tuan-Jie

2013-12-01

Glyphosate is a widely used herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity. Most plants and microbes are sensitive to glyphosate. However, transgenic-resistant crops that contain a modified epsps obtained from the resistant microbes have been commercially successful and therefore, new resistance genes and their adaptive regulatory mechanisms are of great interest. In this study, a soil-borne, glyphosate-resistant bacterium was selected and identified as Enterobacter. The EPSPS in this strain was found to have been altered to a resistant one. A total of 42 differentially expressed genes (DEGs) in the glyphosate were screened using microarray techniques. Under treatment, argF, sdhA, ivbL, rrfA-H were downregulated, whereas the transcripts of speA, osmY, pflB, ahpC, fusA, deoA, uxaC, rpoD and a few ribosomal protein genes were upregulated. Data were verified by quantitative real-time PCR on selected genes. All transcriptional changes appeared to protect the bacteria from glyphosate and associated osmotic, acidic and oxidative stresses. Many DEGs may have the potential to confer resistance to glyphosate alone, and some may be closely related to the shikimate pathway, reflecting the complex gene interaction network for glyphosate resistance. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Investigation of electrochemical intrusion of cations by the method of contact electric resistance

International Nuclear Information System (INIS)

Marichev, V.A.

1997-01-01

Paper shows the possibility and prospects of application of contact electric resistance technique (CER) to study in-situ the initial stages of electrochemical admission of cations (ECA). ECA is shown to increase CER of metals. It enables to determine ECA potential and to investigate kinetics of this process. Using ECA in copper, silver and zinc from alkali solutions as an example one has shown that CER technique enables to obtain results that do not contradict well-known published data. Potentials of ECA cations from acid and neutral solutions in copper, platinum, iron, titanium and tungsten are determined

International Conference on Particle Physics and Astrophysics

CERN Document Server

2015-01-01

The International Conference on Particle Physics and Astrophysics (ICPPA-2015) will be held in Moscow, Russia, from October 5 to 10, 2015. The conference is organized by Center of Basic Research and Particle Physics of National Research Nuclear University “MEPhI”. The aim of the Conference is to promote contacts between scientists and development of new ideas in fundamental research. Therefore we will bring together experts and young scientists working on experimental and theoretical aspects of nuclear, particle, astroparticle physics and cosmology. ICPPA-2015, aims to present the most recent results in astrophysics and collider physics and reports from the main experiments currently taking data. The working languages of the conference are English and Russian.

The learning conference

DEFF Research Database (Denmark)

Ravn, Ib

2007-01-01

/methodology/approach: A typical full-day conference is analyzed. It has six hours of podium talk and twenty-five minutes for delegates to become involved. What model of learning can possibly lie behind this? The transfer model, which assumes learners to be empty vessels. An alternative view is that conference delegates...... are described: Individual reflection, the buzz dyad, ?You have won two consultants, free of charge?, facilitated group work, the knowledge exchange, and lunch with gaffer tape. Originality/value: This paper introduces modern learning theory and techniques into an educational context which has resisted...

An independent occurrence of the chimeric P450 enzyme CYP337B3 of Helicoverpa armigera confers cypermethrin resistance in Pakistan.

Science.gov (United States)

Rasool, Akhtar; Joußen, Nicole; Lorenz, Sybille; Ellinger, Renate; Schneider, Bernd; Khan, Sher Afzal; Ashfaq, Muhammad; Heckel, David G

2014-10-01

The increasing resistance level of insect pest species is a major concern to agriculture worldwide. The cotton bollworm, Helicoverpa armigera, is one of the most important pest species due to being highly polyphagous, geographically widespread, and resistant towards many chemical classes of insecticides. We previously described the mechanism of fenvalerate resistance in Australian populations conferred by the chimeric cytochrome P450 monooxygenase CYP337B3, which arose by unequal crossing-over between CYP337B1 and CYP337B2. Here, we show that this mechanism is also present in the cypermethrin-resistant FSD strain from Pakistan. The Pakistani and the Australian CYP337B3 alleles differ by 18 synonymous and three nonsynonymous SNPs and additionally in the length and sequence of the intron. Nevertheless, the activity of both CYP337B3 proteins is comparable. We demonstrate that CYP337B3 is capable of metabolizing cypermethrin (trans- and especially cis-isomers) to the main metabolite 4'-hydroxycypermethrin, which exhibits no intrinsic toxicity towards susceptible larvae. In a bioassay, CYP337B3 confers a 7-fold resistance towards cypermethrin in FSD larvae compared to susceptible larvae from the Australian TWB strain lacking CYP337B3. Linkage analysis shows that presence of CYP337B3 accounts for most of the cypermethrin resistance in the FSD strain; up-regulation of other P450s in FSD plays no detectable role in resistance. The presence or absence of CYP337B3 can be easily detected by a simple PCR screen, providing a powerful tool to rapidly distinguish resistant from susceptible individuals in the field and to determine the geographical distribution of this resistance gene. Our results suggest that CYP337B3 evolved twice independently by unequal crossing-over between CYP337B2 and two different CYP337B1 alleles. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

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.

SU-C-303-01: Activation-Induced Cytidine Deaminase Confers Cancer Resistance to Radiation Therapy

International Nuclear Information System (INIS)

Yi, S; La Count, S; Liu, J; Bai, X; Lu, L

2015-01-01

Purpose: To study the role of activation-induced cytidine deaminase (AID) in malignant cell resistance to radiation therapy. Methods: We first developed several small devices that could be used to adopt radiation beams from clinical high dose rate brachy therapy (HDR) or linac-based megavoltage machines to perform pre-clinical cell and mouse experiments. Then we used these devices to deliver radiation to AID-positive and AID-silenced cancer cells or tumors formed by these cells in mice. Cells and mice bearing tumors received the same dose under the same experimental conditions. For cells, we observed the apoptosis and the cell survival rate over time. For mice bearing tumors, we measured and recorded the tumor sizes every other day for 4 weeks. Results: For cell experiments, we found that the AID-positive cells underwent much less apoptosis compared with AID-silenced cells upon radiation. And for mouse experiments, we found that AID-positive tumors grew significantly faster than the AID-silenced tumors despite of receiving the same doses of radiation. Conclusion: Our study suggests that AID may confer cancer resistance to radiation therapy, and AID may be a significant biomarker predicting cancer resistance to radiation therapy for certain cancer types

Impact of contact and access resistances in graphene field-effect transistors on quartz substrates for radio frequency applications

International Nuclear Information System (INIS)

Ramón, Michael E.; Movva, Hema C. P.; Fahad Chowdhury, Sk.; Parrish, Kristen N.; Rai, Amritesh; Akinwande, Deji; Banerjee, Sanjay K.; Magnuson, Carl W.; Ruoff, Rodney S.

2014-01-01

High-frequency performance of graphene field-effect transistors (GFETs) has been limited largely by parasitic resistances, including contact resistance (R C ) and access resistance (R A ). Measurement of short-channel (500 nm) GFETs with short (200 nm) spin-on-doped source/drain access regions reveals negligible change in transit frequency (f T ) after doping, as compared to ∼23% f T improvement for similarly sized undoped GFETs measured at low temperature, underscoring the impact of R C on high-frequency performance. DC measurements of undoped/doped short and long-channel GFETs highlight the increasing impact of R A for larger GFETs. Additionally, parasitic capacitances were minimized by device fabrication using graphene transferred onto low-capacitance quartz substrates

Very low resistance alloyed Ni-based ohmic contacts to InP-capped and uncapped n{sup +}-In{sub 0.53} Ga{sub 0.47}As

Energy Technology Data Exchange (ETDEWEB)

Abraham, Michael; Yu, Shih-Ying; Choi, Won Hyuck; Mohney, Suzanne E., E-mail: mohney@ems.psu.edu [Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Lee, Rinus T. P. [SEMATECH, 257 Fuller Road, Suite 2200, Albany, New York 12203 (United States)

2014-10-28

Successful application of the silicide-like Ni{sub x}InGaAs phase for self-aligned source/drain contacts requires the formation of low-resistance ohmic contacts between the phase and underlying InGaAs. We report Ni-based contacts to InP-capped and uncapped n{sup +}- In{sub 0.53}Ga{sub 0.47}As (N{sub D} = 3 × 10{sup 19 }cm{sup −3}) with a specific contact resistance (ρ{sub c}) of 4.0 × 10{sup −8 }± 7 × 10{sup −9} Ω·cm{sup 2} and 4.6 × 10{sup −8 }± 9 × 10{sup −9} Ω·cm{sup 2}, respectively, after annealing at 350 °C for 60 s. With an ammonium sulfide pre-metallization surface treatment, ρ{sub c} is further reduced to 2.1 × 10{sup −8 }± 2 × 10{sup −9} Ω·cm{sup 2} and 1.8 × 10{sup −8 }± 1 × 10{sup −9} Ω·cm{sup 2} on epilayers with and without 10 nm InP caps, respectively. Transmission electron microscopy reveals that the ammonium sulfide surface treatment results in more complete elimination of the semiconductor's native oxide at the contact interface, which is responsible for a reduced contact resistance both before and after annealing.

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.)

Equilibrium contact angle or the most-stable contact angle?

Science.gov (United States)

Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

2014-04-01

It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation. © 2013 Elsevier B.V. All rights reserved.

Molecular characterization of Als1, an acetohydroxyacid synthase mutation conferring resistance to sulfonylurea herbicides in soybean.

Science.gov (United States)

Ghio, Cecilia; Ramos, María Laura; Altieri, Emiliano; Bulos, Mariano; Sala, Carlos A

2013-12-01

The AHAS gene family in soybean was characterized. The locus Als1 for sulfonylurea resistance was mapped and the resistant allele was characterized at the molecular level. Sulfonylurea (SU) resistance in soybean is controlled by Als1, a semi-dominant allele obtained by EMS mutagenesis over the cultivar Williams 82. The overall objective of this research was to map Als1 in the soybean genome and to determine the nucleotidic changes conferring resistance to SU. Four nucleotide sequences (GmAhas1-4) showing high homology with the Arabidopsis thaliana acetohydroxyacid synthase (AHAS, EC 4.1.3.18) gene sequence were identified by in silico analysis, PCR-amplified from the SU-resistant line BTK323STS and sequenced. Expression analysis showed that GmAhas1, located on chromosome 4 by in silico analysis, is the most expressed sequence in true leaves. F2:3 families derived from the cross between susceptible and resistant lines were evaluated for SU resistance. Mapping results indicate that the locus als1 is located on chromosome 4. Sequence comparison of GmAhas1 between BTK323STS and Williams 82 showed a single nucleotide change from cytosine to thymine at position 532. This transversion generates an amino acid change from proline to serine at position 197 (A. thaliana nomenclature) of the AHAS catalytic subunit. An allele-specific marker developed for the GmAhas1 mutant sequence cosegregated with SU resistance in the F2 population. Taking together, the mapping, expression and sequencing results indicate that the GmAhas1 sequence corresponds to the Als1 gene sequence controlling SU resistance in soybean. The molecular breeding tools described herein create the basis to speed up the identification of new mutations in soybean AHAS leading to enhanced levels of resistance to SU or to other families of AHAS inhibitor herbicides.

Plasmid-free CRISPR/Cas9 genome editing in Plasmodium falciparum confirms mutations conferring resistance to the dihydroisoquinolone clinical candidate SJ733.

Directory of Open Access Journals (Sweden)

Emily D Crawford

Full Text Available Genetic manipulation of the deadly malaria parasite Plasmodium falciparum remains challenging, but the rise of CRISPR/Cas9-based genome editing tools is increasing the feasibility of altering this parasite's genome in order to study its biology. Of particular interest is the investigation of drug targets and drug resistance mechanisms, which have major implications for fighting malaria. We present a new method for introducing drug resistance mutations in P. falciparum without the use of plasmids or the need for cloning homologous recombination templates. We demonstrate this method by introducing edits into the sodium efflux channel PfATP4 by transfection of a purified CRISPR/Cas9-guide RNA ribonucleoprotein complex and a 200-nucleotide single-stranded oligodeoxynucleotide (ssODN repair template. Analysis of whole genome sequencing data with the variant-finding program MinorityReport confirmed that only the intended edits were made, and growth inhibition assays confirmed that these mutations confer resistance to the antimalarial SJ733. The method described here is ideally suited for the introduction of mutations that confer a fitness advantage under selection conditions, and the novel finding that an ssODN can function as a repair template in P. falciparum could greatly simplify future editing attempts regardless of the nuclease used or the delivery method.

Stable gene transfer of CCR5 and CXCR4 siRNAs by sleeping beauty transposon system to confer HIV-1 resistance

Directory of Open Access Journals (Sweden)

Akkina Ramesh

2008-07-01

Full Text Available Abstract Background Thus far gene therapy strategies for HIV/AIDS have used either conventional retroviral vectors or lentiviral vectors for gene transfer. Although highly efficient, their use poses a certain degree of risk in terms of viral mediated oncogenesis. Sleeping Beauty (SB transposon system offers a non-viral method of gene transfer to avoid this possible risk. With respect to conferring HIV resistance, stable knock down of HIV-1 coreceptors CCR5 and CXCR4 by the use of lentiviral vector delivered siRNAs has proved to be a promising strategy to protect cells from HIV-1 infection. In the current studies our aim is to evaluate the utility of SB system for stable gene transfer of CCR5 and CXCR4 siRNA genes to derive HIV resistant cells as a first step towards using this system for gene therapy. Results Two well characterized siRNAs against the HIV-1 coreceptors CCR5 and CXCR4 were chosen based on their previous efficacy for the SB transposon gene delivery. The siRNA transgenes were incorporated individually into a modified SB transfer plasmid containing a FACS sortable red fluorescence protein (RFP reporter and a drug selectable neomycin resistance gene. Gene transfer was achieved by co-delivery with a construct expressing a hyperactive transposase (HSB5 into the GHOST-R3/X4/R5 cell line, which expresses the major HIV receptor CD4 and and the co-receptors CCR5 and CXCR4. SB constructs expressing CCR5 or CXCR4 siRNAs were also transfected into MAGI-CCR5 or MAGI-CXCR4 cell lines, respectively. Near complete downregulation of CCR5 and CXCR4 surface expression was observed in transfected cells. During viral challenge with X4-tropic (NL4.3 or R5-tropic (BaL HIV-1 strains, the respective transposed cells showed marked viral resistance. Conclusion SB transposon system can be used to deliver siRNA genes for stable gene transfer. The siRNA genes against HIV-1 coreceptors CCR5 and CXCR4 are able to downregulate the respective cell surface proteins

Autocrine production of TGF-β confers resistance to apoptosis after an epithelial-mesenchymal transition process in hepatocytes: Role of EGF receptor ligands

International Nuclear Information System (INIS)

Castillo, Gaelle del; Murillo, Miguel M.; Alvarez-Barrientos, Alberto; Bertran, Esther; Fernandez, Margarita; Sanchez, Aranzazu; Fabregat, Isabel

2006-01-01

Transforming growth factor-beta (TGF-β) induces apoptosis in fetal rat hepatocytes. However, a subpopulation of these cells survives, concomitant with changes in phenotype, reminiscent of an epithelial-mesenchymal transition (EMT). We have previously suggested that EMT might confer cell resistance to apoptosis (Valdes et al., Mol. Cancer Res., 1: 68-78, 2002). However, the molecular mechanisms responsible for this resistance are not explored yet. In this work, we have isolated and subcultured the population of hepatocytes that suffered the EMT process and are resistant to apoptosis (TGF-β-treated fetal hepatocytes: TβT-FH). We prove that they secrete mitogenic and survival factors, as analyzed by the proliferative and survival capacity of conditioned medium. Inhibition of the epidermal growth factor receptor (EGFR) sensitizes TβT-FH to die after serum withdrawal. TβT-FH expresses high levels of transforming growth factor-alpha (TGF-α) and heparin-binding EGF-like growth factor (HB-EGF) and shows constitutive activation of the EGFR pathway. A blocking anti-TGF-α antibody restores the capacity of cells to die. TGF-β, which is expressed by TβT-FH, mediates up-regulation of TGF-α and HB-EGF expression in those cells. In summary, results suggest that an autocrine loop of TGF-β confers resistance to apoptosis after an EMT process in hepatocytes, through the increase in the expression of EGFR ligands

Geographical gradient of the eIF4E alleles conferring resistance to potyviruses in pea (Pisum) germplasm.

Science.gov (United States)

Konečná, Eva; Šafářová, Dana; Navrátil, Milan; Hanáček, Pavel; Coyne, Clarice; Flavell, Andrew; Vishnyakova, Margarita; Ambrose, Mike; Redden, Robert; Smýkal, Petr

2014-01-01

The eukaryotic translation initiation factor 4E was shown to be involved in resistance against several potyviruses in plants, including pea. We combined our knowledge of pea germplasm diversity with that of the eIF4E gene to identify novel genetic diversity. Germplasm of 2803 pea accessions was screened for eIF4E intron 3 length polymorphism, resulting in the detection of four eIF4E(A-B-C-S) variants, whose distribution was geographically structured. The eIF4E(A) variant conferring resistance to the P1 PSbMV pathotype was found in 53 accessions (1.9%), of which 15 were landraces from India, Afghanistan, Nepal, and 7 were from Ethiopia. A newly discovered variant, eIF4E(B), was present in 328 accessions (11.7%) from Ethiopia (29%), Afghanistan (23%), India (20%), Israel (25%) and China (39%). The eIF4E(C) variant was detected in 91 accessions (3.2% of total) from India (20%), Afghanistan (33%), the Iberian Peninsula (22%) and the Balkans (9.3%). The eIF4E(S) variant for susceptibility predominated as the wild type. Sequencing of 73 samples, identified 34 alleles at the whole gene, 26 at cDNA and 19 protein variants, respectively. Fifteen alleles were virologically tested and 9 alleles (eIF4E(A-1-2-3-4-5-6-7), eIF4E(B-1), eIF4E(C-2)) conferred resistance to the P1 PSbMV pathotype. This work identified novel eIF4E alleles within geographically structured pea germplasm and indicated their independent evolution from the susceptible eIF4E(S1) allele. Despite high variation present in wild Pisum accessions, none of them possessed resistance alleles, supporting a hypothesis of distinct mode of evolution of resistance in wild as opposed to crop species. The Highlands of Central Asia, the northern regions of the Indian subcontinent, Eastern Africa and China were identified as important centers of pea diversity that correspond with the diversity of the pathogen. The series of alleles identified in this study provides the basis to study the co-evolution of potyviruses and the

Ultra-shallow junction (USJ) sheet resistance measurements with a non-penetrating four point probe

International Nuclear Information System (INIS)

Benjamin, M.C.; Hillard, R.J.; Borland, J.O.

2005-01-01

An accurate method to measure the four point probe (4PP) sheet resistance (R S ) of ultra shallow junction (USJ) Source-Drain Extension structures is described. The method utilizes Elastic Material probes (EM-probes) to form non-penetrating contacts to the silicon surface [R.J. Hillard, P.Y. Hung, William Chism, C. Win Ye, W.H. Howland, L.C. Tan, C.E. Kalnas, Characterization and Metrology for ULSI Technology, AIP Conference proceedings 683 (2003) 802.]. The probe design is kinematic and the force is controlled to ensure elastic deformation of the probe material. The probe material is such that large direct tunneling currents can flow through the native oxide thereby forming a low impedance contact. Sheet resistance measurements on USJ implanted P+/N structures with Secondary Ion Mass Spectroscopy (SIMS) junction depths less than 15 nm have been measured. The method is demonstrated on implanted USJ structures and found to be consistent with expectations

75 FR 51825 - Quality and Compliance in Merging and Emerging Cultures; Public Conference

Science.gov (United States)

2010-08-23

... announcing a public conference entitled ``The New Paradigm: Quality and Compliance in Merging and Emerging... accommodations because of a disability, please contact Wanda Neal, at least 7 days in advance of the conference...

NMOS contact resistance reduction with selenium implant into NiPt silicide

Science.gov (United States)

Rao, K. V.; Khaja, F. A.; Ni, C. N.; Muthukrishnan, S.; Darlark, A.; Lei, J.; Peidous, I.; Brand, A.; Henry, T.; Variam, N.; Erokhin, Y.

2012-11-01

A 25% reduction in NMOS contact resistance (Rc) was achieved by Selenium implantation into NiPt silicide film in VIISta Trident high-current single-wafer implanter. The Trident implanter is designed for shallow high-dose implants with high beam currents to maintain high throughput (for low CoO), with improved micro-uniformity and no energy contamination. The integration of Se implant was realized using a test chip dedicated to investigating silicide/junction related electrical properties and testable after silicidation. The silicide module processes were optimized, including the pre-clean (prior to RF PVD NiPt dep) and pre- and post-implant anneals. A 270°C soak anneal was used for RTP1, whereas a msec laser anneal was employed for RTP2 with sufficient process window (800-850°C), while maintaining excellent junction characteristics without Rs degradation.

Impact of contact and access resistances in graphene field-effect transistors on quartz substrates for radio frequency applications

Energy Technology Data Exchange (ETDEWEB)

Ramón, Michael E., E-mail: michael.ramon@utexas.edu, E-mail: hemacp@utexas.edu; Movva, Hema C. P., E-mail: michael.ramon@utexas.edu, E-mail: hemacp@utexas.edu; Fahad Chowdhury, Sk.; Parrish, Kristen N.; Rai, Amritesh; Akinwande, Deji; Banerjee, Sanjay K. [Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758 (United States); Magnuson, Carl W.; Ruoff, Rodney S. [Department of Mechanical Engineering and the Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas 78712 (United States)

2014-02-17

High-frequency performance of graphene field-effect transistors (GFETs) has been limited largely by parasitic resistances, including contact resistance (R{sub C}) and access resistance (R{sub A}). Measurement of short-channel (500 nm) GFETs with short (200 nm) spin-on-doped source/drain access regions reveals negligible change in transit frequency (f{sub T}) after doping, as compared to ∼23% f{sub T} improvement for similarly sized undoped GFETs measured at low temperature, underscoring the impact of R{sub C} on high-frequency performance. DC measurements of undoped/doped short and long-channel GFETs highlight the increasing impact of R{sub A} for larger GFETs. Additionally, parasitic capacitances were minimized by device fabrication using graphene transferred onto low-capacitance quartz substrates.

The identification of candidate rice genes that confer resistance to the brown planthopper (Nilaparvata lugens) through representational difference analysis.

Science.gov (United States)

Park, Dong-Soo; Lee, Sang-Kyu; Lee, Jong-Hee; Song, Min-Young; Song, Song-Yi; Kwak, Do-Yeon; Yeo, Un-Sang; Jeon, Nam-Soo; Park, Soo-Kwon; Yi, Gihwan; Song, You-Chun; Nam, Min-Hee; Ku, Yeon-Chung; Jeon, Jong-Seong

2007-08-01

The development of rice varieties (Oryza sativa L.) that are resistant to the brown planthopper (BPH; Nilaparvata lugens Stål) is an important objective in current breeding programs. In this study, we generated 132 BC(5)F(5) near-isogenic rice lines (NILs) by five backcrosses of Samgangbyeo, a BPH resistant indica variety carrying the Bph1 locus, with Nagdongbyeo, a BPH susceptible japonica variety. To identify genes that confer BPH resistance, we employed representational difference analysis (RDA) to detect transcripts that were exclusively expressed in one of our BPH resistant NIL, SNBC61, during insect feeding. The chromosomal mapping of the RDA clones that we subsequently isolated revealed that they are located in close proximity either to known quantitative trait loci or to an introgressed SSR marker from the BPH resistant donor parent Samgangbyeo. Genomic DNA gel-blot analysis further revealed that loci of all RDA clones in SNBC61 correspond to the alleles of Samgangbyeo. Most of the RDA clones were found to be exclusively expressed in SNBC61 and could be assigned to functional groups involved in plant defense. These RDA clones therefore represent candidate defense genes for BPH resistance.

Transport physics and device modeling of zinc oxide thin-film transistors. Pt. II: Contact Resistance in Short Channel Devices

NARCIS (Netherlands)

Torricelli, F.; Meijboom, J.R.; Smits, E.; Tripathi, A.K.; Gelinck, G.H.; Colalongo, L.; Kovacs-Vajna, Z.M.; Leeuw, D. de; Cantatore, E.

2011-01-01

Abstract—Short-channel zinc oxide (ZnO) thin-film transistors (TFTs) are investigated in a wide range of temperatures and bias conditions. Scaling down the channel length, the TFT performance is seriously affected by contact resistances, which depend on gate voltage and temperature. To account for

Transport physics and device modeling of zinc oxide thin film transistors - part II : contact resistance in short channel devices

NARCIS (Netherlands)

Torricelli, F.; Smits, E.C.P.; Meijboom, J.R.; Tripathi, A.K.; Gelinck, G.H.; Colalongo, L.; Kovacs-Vajna, Z.M.; Cantatore, E.

2011-01-01

Short-channel zinc oxide (ZnO) thin-film transistors (TFTs) are investigated in a wide range of temperatures and bias conditions. Scaling down the channel length, the TFT performance is seriously affected by contact resistances, which depend on gate voltage and temperature. To account for the

In Vivo-Selected Compensatory Mutations Restore the Fitness Cost of Mosaic penA Alleles That Confer Ceftriaxone Resistance in Neisseria gonorrhoeae.

Science.gov (United States)

Vincent, Leah R; Kerr, Samuel R; Tan, Yang; Tomberg, Joshua; Raterman, Erica L; Dunning Hotopp, Julie C; Unemo, Magnus; Nicholas, Robert A; Jerse, Ann E

2018-04-03

Resistance to ceftriaxone in Neisseria gonorrhoeae is mainly conferred by mosaic penA alleles that encode penicillin-binding protein 2 (PBP2) variants with markedly lower rates of acylation by ceftriaxone. To assess the impact of these mosaic penA alleles on gonococcal fitness, we introduced the mosaic penA alleles from two ceftriaxone-resistant (Cro r ) clinical isolates (H041 and F89) into a Cro s strain (FA19) by allelic exchange and showed that the resultant Cro r mutants were significantly outcompeted by the Cro s parent strain in vitro and in a murine infection model. Four Cro r compensatory mutants of FA19 penA41 were isolated independently from mice that outcompeted the parent strain both in vitro and in vivo One of these compensatory mutants (LV41C) displayed a unique growth profile, with rapid log growth followed by a sharp plateau/gradual decline at stationary phase. Genome sequencing of LV41C revealed a mutation (G348D) in the acnB gene encoding the bifunctional aconitate hydratase 2/2 methylisocitrate dehydratase. Introduction of the acnB G348D allele into FA19 penA41 conferred both a growth profile that phenocopied that of LV41C and a fitness advantage, although not as strongly as that exhibited by the original compensatory mutant, suggesting the existence of additional compensatory mutations. The mutant aconitase appears to be a functional knockout with lower activity and expression than wild-type aconitase. Transcriptome sequencing (RNA-seq) analysis of FA19 penA41 acnB G348D revealed a large set of upregulated genes involved in carbon and energy metabolism. We conclude that compensatory mutations can be selected in Cro r gonococcal strains that increase metabolism to ameliorate their fitness deficit. IMPORTANCE The emergence of ceftriaxone-resistant (Cro r ) Neisseria gonorrhoeae has led to the looming threat of untreatable gonorrhea. Whether Cro resistance is likely to spread can be predicted from studies that compare the relative fitnesses of

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.

Measurement of Dynamic Resistance in Resistance Spot Welding

DEFF Research Database (Denmark)

Wu, Pei; Zhang, Wenqi; Bay, Niels

Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side of the transfo......Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side...

Measurement of inter-strand contact resistance in epoxy impregnated Nb3Sn Rutherford cables

International Nuclear Information System (INIS)

Giorgio Ambrosio

2003-01-01

An apparatus for the measurement, under transverse pressure, of the inter-strand contact resistance in epoxy-impregnated Nb 3 Sn Rutherford cables has been recently assembled at Fermilab. Procedures have been developed to instrument and measure samples extracted from Nb 3 Sn coils. Samples were extracted from coils fabricated with the Wind-and-React and the React-and-Wind technology, both presently under development at Fermilab. A ceramic binder is used to improve the insulation and to simplify the fabrication of coils using the Wind-and-React technology. Synthetic oil is used to prevent sintering during the heat treatment of coils to be wound after reaction. In order to evaluate the effects of the ceramic binder and of the synthetic oil on the inter-strand resistance, measurements of samples extracted from coils were compared with measurements of cable stacks with varying characteristics. In this paper we describe the apparatus, the sample preparation, the measurement procedure, and the results of the first series of tests

Effect of Chlorine Exposure on the Survival and Antibiotic Gene Expression of Multidrug Resistant Acinetobacter baumannii in Water

Directory of Open Access Journals (Sweden)

Deepti Prasad Karumathil

2014-02-01

Full Text Available Acinetobacter baumannii is a multidrug resistant pathogen capable of causing a wide spectrum of clinical conditions in humans. Acinetobacter spp. is ubiquitously found in different water sources. Chlorine being the most commonly used disinfectant in water, the study investigated the effect of chlorine on the survival of A. baumannii in water and transcription of genes conferring antibiotic resistance. Eight clinical isolates of A. baumannii, including a fatal meningitis isolate (ATCC 17978 (~108 CFU/mL were separately exposed to free chlorine concentrations (0.2, 1, 2, 3 and 4 ppm with a contact time of 30, 60, 90 and 120 second. The surviving pathogen counts at each specified contact time were determined using broth dilution assay. In addition, real-time quantitative PCR (RT-qPCR analysis of the antibiotic resistance genes (efflux pump genes and those encoding resistance to specific antibiotics of three selected A. baumannii strains following exposure to chlorine was performed. Results revealed that all eight A. baumannii isolates survived the tested chlorine levels during all exposure times (p > 0.05. Additionally, there was an up-regulation of all or some of the antibiotic resistance genes in A. baumannii, indicating a chlorine-associated induction of antibiotic resistance in the pathogen.

Loss of the RNA polymerase III repressor MAF1 confers obesity resistance.

Science.gov (United States)

Bonhoure, Nicolas; Byrnes, Ashlee; Moir, Robyn D; Hodroj, Wassim; Preitner, Frédéric; Praz, Viviane; Marcelin, Genevieve; Chua, Streamson C; Martinez-Lopez, Nuria; Singh, Rajat; Moullan, Norman; Auwerx, Johan; Willemin, Gilles; Shah, Hardik; Hartil, Kirsten; Vaitheesvaran, Bhavapriya; Kurland, Irwin; Hernandez, Nouria; Willis, Ian M

2015-05-01

MAF1 is a global repressor of RNA polymerase III transcription that regulates the expression of highly abundant noncoding RNAs in response to nutrient availability and cellular stress. Thus, MAF1 function is thought to be important for metabolic economy. Here we show that a whole-body knockout of Maf1 in mice confers resistance to diet-induced obesity and nonalcoholic fatty liver disease by reducing food intake and increasing metabolic inefficiency. Energy expenditure in Maf1(-/-) mice is increased by several mechanisms. Precursor tRNA synthesis was increased in multiple tissues without significant effects on mature tRNA levels, implying increased turnover in a futile tRNA cycle. Elevated futile cycling of hepatic lipids was also observed. Metabolite profiling of the liver and skeletal muscle revealed elevated levels of many amino acids and spermidine, which links the induction of autophagy in Maf1(-/-) mice with their extended life span. The increase in spermidine was accompanied by reduced levels of nicotinamide N-methyltransferase, which promotes polyamine synthesis, enables nicotinamide salvage to regenerate NAD(+), and is associated with obesity resistance. Consistent with this, NAD(+) levels were increased in muscle. The importance of MAF1 for metabolic economy reveals the potential for MAF1 modulators to protect against obesity and its harmful consequences. © 2015 Bonhoure et al.; Published by Cold Spring Harbor Laboratory Press.

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

Pancreatic adenocarcinoma upregulated factor (PAUF) confers resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNA receptor-mediated signaling

Energy Technology Data Exchange (ETDEWEB)

Kaowinn, Sirichat; Cho, Il-Rae; Moon, Jeong; Jun, Seung Won; Kim, Chang Seok [BK21+, Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-736 (Korea, Republic of); Kang, Ho Young [Department of Microbiology, Pusan National University, Busan 609-736 (Korea, Republic of); Kim, Manbok [Department of Medical Science, Dankook University College of Medicine, Cheonan 330-714 (Korea, Republic of); Koh, Sang Seok [Department of Biological Sciences, Dong-A University, Busan 604-714 (Korea, Republic of); Chung, Young-Hwa, E-mail: younghc@pusan.ac.kr [BK21+, Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-736 (Korea, Republic of)

2015-04-03

Pancreatic adenocarcinoma upregulated factor (PAUF), a novel oncogene, plays a crucial role in the development of pancreatic cancer, including its metastasis and proliferation. Therefore, PAUF-expressing pancreatic cancer cells could be important targets for oncolytic virus-mediated treatment. Panc-1 cells expressing PAUF (Panc-PAUF) showed relative resistance to parvovirus H-1 infection compared with Panc-1 cells expressing an empty vector (Panc-Vec). Of interest, expression of type I IFN-α receptor (IFNAR) was higher in Panc-PAUF cells than in Panc-Vec cells. Increased expression of IFNAR in turn increased the activation of Stat1 and Tyk2 in Panc-PAUF cells compared with that in Panc-Vec cells. Suppression of Tyk2 and Stat1, which are important downstream molecules for IFN-α signaling, sensitized pancreatic cancer cells to parvovirus H-1-mediated apoptosis. Further, constitutive suppression of PAUF sensitized Bxpc3 pancreatic cancer cells to parvovirus H-1 infection. Taken together, these results suggested that PAUF conferred resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNAR-mediated signaling. - Highlights: • PAUF confers resistance against oncolytic parvovirus H-1 infection. • PAUF enhances the expression of IFNAR in Panc-1 cells. • Increased activation of Tyk2 or Stat1 by PAUF provides resistance to parvovirus H-1-mediated apoptosis. • Constitutive inhibition of PAUF enhances parvovirus H-1-mediated oncolysis of Bxpc3 pancreatic cancer cells.

Pancreatic adenocarcinoma upregulated factor (PAUF) confers resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNA receptor-mediated signaling

International Nuclear Information System (INIS)

Kaowinn, Sirichat; Cho, Il-Rae; Moon, Jeong; Jun, Seung Won; Kim, Chang Seok; Kang, Ho Young; Kim, Manbok; Koh, Sang Seok; Chung, Young-Hwa

2015-01-01

Pancreatic adenocarcinoma upregulated factor (PAUF), a novel oncogene, plays a crucial role in the development of pancreatic cancer, including its metastasis and proliferation. Therefore, PAUF-expressing pancreatic cancer cells could be important targets for oncolytic virus-mediated treatment. Panc-1 cells expressing PAUF (Panc-PAUF) showed relative resistance to parvovirus H-1 infection compared with Panc-1 cells expressing an empty vector (Panc-Vec). Of interest, expression of type I IFN-α receptor (IFNAR) was higher in Panc-PAUF cells than in Panc-Vec cells. Increased expression of IFNAR in turn increased the activation of Stat1 and Tyk2 in Panc-PAUF cells compared with that in Panc-Vec cells. Suppression of Tyk2 and Stat1, which are important downstream molecules for IFN-α signaling, sensitized pancreatic cancer cells to parvovirus H-1-mediated apoptosis. Further, constitutive suppression of PAUF sensitized Bxpc3 pancreatic cancer cells to parvovirus H-1 infection. Taken together, these results suggested that PAUF conferred resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNAR-mediated signaling. - Highlights: • PAUF confers resistance against oncolytic parvovirus H-1 infection. • PAUF enhances the expression of IFNAR in Panc-1 cells. • Increased activation of Tyk2 or Stat1 by PAUF provides resistance to parvovirus H-1-mediated apoptosis. • Constitutive inhibition of PAUF enhances parvovirus H-1-mediated oncolysis of Bxpc3 pancreatic cancer cells

Insights into the structure, function and evolution of the radical-SAM 23S rRNA methyltransferase Cfr that confers antibiotic resistance in bacteria

DEFF Research Database (Denmark)

Karminska, K. H.; Purta, E.; Hansen, L .H.

2010-01-01

The Cfr methyltransferase confers combined resistance to five classes of antibiotics that bind to the peptidyl tranferase center of bacterial ribosomes by catalyzing methylation of the C-8 position of 23S rRNA nucleotide A2503. The same nucleotide is targeted by the housekeeping methyltransferase...

Connective tissue growth factor confers drug resistance in breast cancer through concomitant up-regulation of Bcl-xL and cIAP1.

Science.gov (United States)

Wang, Ming-Yang; Chen, Pai-Sheng; Prakash, Ekambaranellore; Hsu, Hsing-Chih; Huang, Hsin-Yi; Lin, Ming-Tsan; Chang, King-Jen; Kuo, Min-Liang

2009-04-15

Connective tissue growth factor (CTGF) expression is elevated in advanced breast cancer and promotes metastasis. Chemotherapy response is only transient in most metastatic diseases. In the present study, we examined whether CTGF expression could confer drug resistance in human breast cancer. In breast cancer patients who received neoadjuvant chemotherapy, CTGF expression was inversely associated with chemotherapy response. Overexpression of CTGF in MCF7 cells (MCF7/CTGF) enhanced clonogenic ability, cell viability, and resistance to apoptosis on exposure to doxorubicin and paclitaxel. Reducing the CTGF level in MDA-MB-231 (MDA231) cells by antisense CTGF cDNA (MDA231/AS cells) mitigated this drug resistance capacity. CTGF overexpression resulted in resistance to doxorubicin- and paclitaxel-induced apoptosis by up-regulation of Bcl-xL and cellular inhibitor of apoptosis protein 1 (cIAP1). Knockdown of Bcl-xL or cIAP1 with specific small interfering RNAs abolished the CTGF-mediated resistance to apoptosis induced by the chemotherapeutic agents in MCF7/CTGF cells. Inhibition of extracellular signal-regulated kinase (ERK)-1/2 effectively reversed the resistance to apoptosis as well as the up-regulation of Bcl-xL and cIAP1 in MCF7/CTGF cells. A neutralizing antibody against integrin alpha(v)beta(3) significantly attenuated CTGF-mediated ERK1/2 activation and up-regulation of Bcl-xL and cIAP1, indicating that the integrin alpha(v)beta(3)/ERK1/2 signaling pathway is essential for CTGF functions. The Bcl-xL level also correlated with the CTGF level in breast cancer patients. We also found that a COOH-terminal domain peptide from CTGF could exert activities similar to full-length CTGF, in activation of ERK1/2, up-regulation of Bcl-xL/cIAP1, and resistance to apoptosis. We conclude that CTGF expression could confer resistance to chemotherapeutic agents through augmenting a survival pathway through ERK1/2-dependent Bcl-xL/cIAP1 up-regulation.

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

Current simulation of symmetric contacts on CdTe

International Nuclear Information System (INIS)

Ruzin, A.

2011-01-01

This article presents the calculated current-voltage characteristics of symmetric Metal-Semiconductor-Metal configurations for Schottky, Ohmic, and injecting-Ohmic contacts on high resistivity CdTe. The results clearly demonstrate that in the wide band-gap, semi-insulating semiconductors, such as high resistivity CdTe, the linearity of the I-V curves cannot be considered a proof of the ohmicity of the contacts. It is shown that the linear I-V curves are expected for a wide range of contact barriers. Furthermore, the slope of these linear curves is governed by the barrier height, rather than the bulk doping concentration. Therefore the deduction of bulk's resistivity from the I-V curves may be false.

Current simulation of symmetric contacts on CdTe

Energy Technology Data Exchange (ETDEWEB)

Ruzin, A., E-mail: aruzin@post.tau.ac.il [School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv (Israel)

2011-12-01

This article presents the calculated current-voltage characteristics of symmetric Metal-Semiconductor-Metal configurations for Schottky, Ohmic, and injecting-Ohmic contacts on high resistivity CdTe. The results clearly demonstrate that in the wide band-gap, semi-insulating semiconductors, such as high resistivity CdTe, the linearity of the I-V curves cannot be considered a proof of the ohmicity of the contacts. It is shown that the linear I-V curves are expected for a wide range of contact barriers. Furthermore, the slope of these linear curves is governed by the barrier height, rather than the bulk doping concentration. Therefore the deduction of bulk's resistivity from the I-V curves may be false.

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).

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

International Nuclear Information System (INIS)

Basiricò, L; Lanzara, G

2012-01-01

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). (paper)

Mutation at codon 442 in the rpoB gene of Mycobacterium leprae does not confer resistance to rifampicin.

Science.gov (United States)

Lavania, Mallika; Hena, Abu; Reja, Hasanoor; Nigam, Astha; Biswas, Nibir Kumar; Singh, Itu; Turankar, Ravindra P; Gupta, Ud; Kumar, Senthil; Rewaria, Latika; Patra, Pradip K R; Sengupta, Utpal; Bhattacharya, Basudeb

2016-03-01

Rifampicin is the major drug in the treatment of leprosy. The rifampicin resistance of Mycobacterium leprae results from a mutation in the rpoB gene, encoding the β subunit of RNA polymerase. As M. leprae is a non-cultivable organism observation of its growth using mouse food-pad (MFP) is the only Gold Standard assay used for confirmation of "in-vivo" drug resistance. Any mutation at molecular level has to be verified by MFP assay for final confirmation of drug resistance in leprosy. In the present study, M. leprae strains showing a mutation only at codon 442 Gln-His and along with mutation either at codon 424 Val-Gly or at 438 Gln-Val within the Rifampicin Resistance Determining Region (RRDR) confirmed by DNA sequencing and by high resolution melting (HRM) analysis were subjected for its growth in MFP. The M. leprae strain having the new mutation at codon 442 Gln-His was found to be sensitive to all the three drugs and strains having additional mutations at 424 Val-Gly and 438 Gln-Val were conferring resistance with Multi drug therapy (MDT) in MFP. These results indicate that MFP is the gold standard method for confirming the mutations detected by molecular techniques.

Accumulation of multiple mutations in linezolid-resistant Staphylococcus epidermidis causing bloodstream infections; in silico analysis of L3 amino acid substitutions that might confer high-level linezolid resistance.

Science.gov (United States)

Ikonomidis, Alexandros; Grapsa, Anastasia; Pavlioglou, Charikleia; Demiri, Antonia; Batarli, Alexandra; Panopoulou, Maria

2016-12-01

Fifty-six Staphylococcus epidermidis clinical isolates, showing high-level linezolid resistance and causing bacteremia in critically ill patients, were studied. All isolates belonged to ST22 clone and carried the T2504A and C2534T mutations in gene coding for 23SrRNA as well as the C189A, G208A, C209T and G384C missense mutations in L3 protein which resulted in Asp159Tyr, Gly152Asp and Leu94Val substitutions. Other silent mutations were also detected in genes coding for ribosomal proteins L3 and L22. In silico analysis of missense mutations showed that although L3 protein retained the sequence of secondary motifs, the tertiary structure was influenced. The observed alteration in L3 protein folding provides an indication on the putative role of L3-coding gene mutations in high-level linezolid resistance. Furthermore, linezolid pressure in health care settings where linezolid consumption is of high rates might lead to the selection of resistant mutants possessing L3 mutations that might confer high-level linezolid resistance.

PREFACE: Non-contact AFM Non-contact AFM

Science.gov (United States)

Giessibl, Franz J.; Morita, Seizo

2012-02-01

This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of

Design and fabrication stable LNF contact for future IC application

International Nuclear Information System (INIS)

Bhuiyan, M M I; Bhuiyan, M; Rashid, M M; Ahmed, Sayem; Kajihara, M

2013-01-01

Enable the design of a small contact spring for applications requiring high density, high speed and high durability. A low normal force (LNF) contact spring with high performance is fabricated using a unique combined MEMS photo resist lithography and electro fine forming (EFF) technology. Reducing a total contact material cost of a connector, a high-Hertz stress with LNF contact will be a key technology in the future. Only radius R 5μm tip with 0.1N force contact provides an excellent electrical performance which is much sharper than conventional contact. 0.30million cycle's durability test was passed at 300μm displacement and the contact resistance was ≤50mΩ

Cereal cyst nematode resistance conferred by the Cre7 gene from Aegilops triuncialis and its relationship with Cre genes from Australian wheat cultivars

OpenAIRE

Montes, Maria Jesus; Andrés, María Fe; Sin, E.; Lopez Braña, Isidoro; Martín-Sánchez, J.A.; Romero, M.D.; Delibes Castro, Angeles

2008-01-01

Cereal cyst nematode (CCN; Heterodera avenae Woll.) is a root pathogen of cereal crops that can cause severe yield losses in wheat (Triticum aestivum). Differential host–nematode interactions occur in wheat cultivars carrying different CCN resistance (Cre) genes. The objective of this study was to determine the CCN resistance conferred by the Cre7 gene from Aegilops triuncialis in a 42-chromosome introgression line and to assess the effects of the Cre1, Cre3, Cre4, and Cre8 genes present in A...

Titanium contacts to graphene: process-induced variability in electronic and thermal transport

Science.gov (United States)

Freedy, Keren M.; Giri, Ashutosh; Foley, Brian M.; Barone, Matthew R.; Hopkins, Patrick E.; McDonnell, Stephen

2018-04-01

Contact resistance (R C) is a major limiting factor in the performance of graphene devices. R C is sensitive to the quality of the interface and the composition of the contact, which are affected by the graphene transfer process and contact deposition conditions. In this work, a linear correlation is observed between the composition of Ti contacts, characterized by x-ray photoelectron spectroscopy, and the Ti/graphene contact resistance measured by the transfer length method. We find that contact composition is tunable via deposition rate and base pressure. Reactor base pressure is found to effect the resultant contact resistance. The effect of contact deposition conditions on thermal transport measured by time-domain thermoreflectance is also reported. Interfaces with higher oxide composition appear to result in a lower thermal boundary conductance. Possible origins of this thermal boundary conductance change with oxide composition are discussed.

Computing Conference at Bologna

International Nuclear Information System (INIS)

Anon.

1980-01-01

From 9-12 September a Europhysics Conference on Computing in High Energy and Nuclear Physics, organized by the Computational Physics Group of the European Physical Society, was held in Bologna, attracting some 150 participants. Its purpose was contact and exchange of information between experimental physicists (from both fields of research) and computer experts (on whom the successful outcome of the research has become increasingly dependent)

Association Mapping of Quantitative Trait Loci in Spring Wheat Landraces Conferring Resistance to Bacterial Leaf Streak and Spot Blotch

Directory of Open Access Journals (Sweden)

Tika B. Adhikari

2012-03-01

Full Text Available Bacterial leaf streak (BLS, caused by pv. (Smith et al. Bragard et al., and spot blotch (SB, caused by (S. Ito & Kurib. Drechs. ex Dastur, are two emerging diseases of wheat ( L.. To achieve sustainable disease management strategies and reduce yield losses, identifying new genes that confer quantitative resistance would benefit resistance breeding efforts. The main objective of this study was to use association mapping (AM with 832 polymorphic Diversity Arrays Technology (DArT markers to identify genomic regions associated with resistance to BLS and SB in 566 spring wheat landraces. From data analysis of this diverse panel of wheat accessions, we discovered five novel genomic regions significantly associated with resistance to BLS on chromosomes 1A, 4A, 4B, 6B, and 7D. Similarly, four genomic regions were found to be associated with resistance to SB on chromosomes 1A, 3B, 7B, and 7D. A high degree of linkage disequilibrium (LD decayed over short genetic distance in the set of wheat accessions studied, and some of these genomic regions appear to be involved in multiple disease resistance (MDR. These results suggest that the AM approach provides a platform for discovery of resistance conditioned by multiple genes with quantitative effects, which could be validated and deployed in wheat breeding programs.

Impact of contact resistance on the electrical properties of MoS2 transistors at practical operating temperatures

Directory of Open Access Journals (Sweden)

Filippo Giannazzo

2017-01-01

Full Text Available Molybdenum disulphide (MoS2 is currently regarded as a promising material for the next generation of electronic and optoelectronic devices. However, several issues need to be addressed to fully exploit its potential for field effect transistor (FET applications. In this context, the contact resistance, RC, associated with the Schottky barrier between source/drain metals and MoS2 currently represents one of the main limiting factors for suitable device performance. Furthermore, to gain a deeper understanding of MoS2 FETs under practical operating conditions, it is necessary to investigate the temperature dependence of the main electrical parameters, such as the field effect mobility (μ and the threshold voltage (Vth. This paper reports a detailed electrical characterization of back-gated multilayer MoS2 transistors with Ni source/drain contacts at temperatures from T = 298 to 373 K, i.e., the expected range for transistor operation in circuits/systems, considering heating effects due to inefficient power dissipation. From the analysis of the transfer characteristics (ID−VG in the subthreshold regime, the Schottky barrier height (ΦB ≈ 0.18 eV associated with the Ni/MoS2 contact was evaluated. The resulting contact resistance in the on-state (electron accumulation in the channel was also determined and it was found to increase with T as RC proportional to T3.1. The contribution of RC to the extraction of μ and Vth was evaluated, showing a more than 10% underestimation of μ when the effect of RC is neglected, whereas the effect on Vth is less significant. The temperature dependence of μ and Vth was also investigated. A decrease of μ proportional to 1/Tα with α = 1.4 ± 0.3 was found, indicating scattering by optical phonons as the main limiting mechanism for mobility above room temperature. The value of Vth showed a large negative shift (about 6 V increasing the temperature from 298 to 373 K, which was explained in terms of electron

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)

77 FR 1051 - General Conference Committee of the National Poultry Improvement Plan; Meeting

Science.gov (United States)

2012-01-09

...] General Conference Committee of the National Poultry Improvement Plan; Meeting AGENCY: Animal and Plant... the General Conference Committee of the National Poultry Improvement Plan. DATES: The meeting will be... INFORMATION CONTACT: Dr. C. Stephen Roney, Senior Coordinator, National Poultry Improvement Plan, VS, APHIS...

Magnetic field and contact resistance dependence of non-local charge imbalance

International Nuclear Information System (INIS)

Kleine, A; Baumgartner, A; Trbovic, J; Schoenenberger, C; Golubev, D S; Zaikin, A D

2010-01-01

Crossed Andreev reflection (CAR) in metallic nanostructures, a possible basis for solid-state electron entangler devices, is usually investigated by detecting non-local voltages in multi-terminal superconductor/normal metal devices. This task is difficult because other subgap processes may mask the effects of CAR. One of these processes is the generation of charge imbalance (CI) and the diffusion of non-equilibrium quasi-particles in the superconductor. Here we demonstrate a characteristic dependence of non-local CI on a magnetic field applied parallel to the superconducting wire, which can be understood by a generalization of the standard description of CI to non-local experiments. These results can be used to distinguish CAR and CI and to extract CI relaxation times in superconducting nanostructures. In addition, we investigate the dependence of non-local CI on the resistance of the injector and detector contacts and demonstrate a quantitative agreement with a recent theory using only material and junction characteristics extracted from separate direct measurements.

Perceived Discrimination and Interracial Contact: Predicting Interracial Closeness among Black and White Americans

Science.gov (United States)

Tropp, Linda R.

2007-01-01

This research examines whether perceptions of discrimination moderate relationships between interracial contact and feelings of interracial closeness among black and white Americans, using survey responses gathered by the National Conference for Community and Justice (2000). Results indicate that the general association between contact and…

New Developments in the Field of Materials for Electric Power Engineering. Paper presented at the ETG Conference (Energy Technology Society) 1981

Energy Technology Data Exchange (ETDEWEB)

1981-01-01

The Conference Proceedings comprise 21 papers divided into 4 theme groups: insulating materials and insulating systems; structural materials; magnetic materials; conductor and contact materials. Individual papers deal with: the search for a new insulating system for transformers; insulating oils and liquids; an insulating system for electric machines of high heat resistance: progress in insulation of exciter winding in hydroelectic generators and other large synchronous machines; insulating systems for extreme envronmental conditions; behavior of silicon elastomer, organic, and polyethylene insulating materials; development of new magnetic materials, in particular: metallic glasses; amorphous magnetic materials; pressed iron powder parts; modern permanent magnetic materials; development of new contact materials for power switchgear; alternative switchgear technologies; a new cryogenic conductor structured element based on V/sub 2/O/sub 3/ ceramic; choice of material for fuses.

Alpha-tocopherol transfer protein disruption confers resistance to malarial infection in mice

Directory of Open Access Journals (Sweden)

Takeya Motohiro

2010-04-01

Full Text Available Abstract Background Various factors impact the severity of malaria, including the nutritional status of the host. Vitamin E, an intra and extracellular anti-oxidant, is one such nutrient whose absence was shown previously to negatively affect Plasmodium development. However, mechanisms of this Plasmodium inhibition, in addition to means by which to exploit this finding as a therapeutic strategy, remain unclear. Methods α-TTP knockout mice were infected with Plasmodium berghei NK65 or Plasmodium yoelii XL-17, parasitaemia, survival rate were monitored. In one part of the experiments mice were fed with a supplemented diet of vitamin E and then infected. In addition, parasite DNA damage was monitored by means of comet assay and 8-OHdG test. Moreover, infected mice were treated with chloroquine and parasitaemia and survival rate were monitored. Results Inhibition of α-tocopherol transfer protein (α-TTP, a determinant of vitamin E concentration in circulation, confers resistance to malarial infection as a result of oxidative damage to the parasites. Furthermore, in combination with the anti-malarial drug chloroquine results were even more dramatic. Conclusion Considering that these knockout mice lack observable negative impacts typical of vitamin E deficiency, these results suggest that inhibition of α-TTP activity in the liver may be a useful strategy in the prevention and treatment of malaria infection. Moreover, a combined strategy of α-TTP inhibition and chloroquine treatment might be effective against drug resistant parasites.

Contact resistance and overlapping capacitance in flexible sub-micron long oxide thin-film transistors for above 100 MHz operation

Energy Technology Data Exchange (ETDEWEB)

Münzenrieder, Niko, E-mail: muenzenrieder@ife.ee.ethz.ch; Salvatore, Giovanni A.; Petti, Luisa; Zysset, Christoph; Büthe, Lars; Vogt, Christian; Cantarella, Giuseppe; Tröster, Gerhard [Electronics Laboratory Swiss Federal Institute of Technology (ETH) Zürich, Gloriastrasse 35, 8092 Zürich (Switzerland)

2014-12-29

In recent years new forms of electronic devices such as electronic papers, flexible displays, epidermal sensors, and smart textiles have become reality. Thin-film transistors (TFTs) are the basic blocks of the circuits used in such devices and need to operate above 100 MHz to efficiently treat signals in RF systems and address pixels in high resolution displays. Beyond the choice of the semiconductor, i.e., silicon, graphene, organics, or amorphous oxides, the junctionless nature of TFTs and its geometry imply some limitations which become evident and important in devices with scaled channel length. Furthermore, the mechanical instability of flexible substrates limits the feature size of flexible TFTs. Contact resistance and overlapping capacitance are two parasitic effects which limit the transit frequency of transistors. They are often considered independent, while a deeper analysis of TFTs geometry imposes to handle them together; in fact, they both depend on the overlapping length (L{sub OV}) between source/drain and the gate contacts. Here, we conduct a quantitative analysis based on a large number of flexible ultra-scaled IGZO TFTs. Devices with three different values of overlap length and channel length down to 0.5 μm are fabricated to experimentally investigate the scaling behavior of the transit frequency. Contact resistance and overlapping capacitance depend in opposite ways on L{sub OV}. These findings establish routes for the optimization of the dimension of source/drain contact pads and suggest design guidelines to achieve megahertz operation in flexible IGZO TFTs and circuits.

Conference to Focus on Vast Need for 'Village Power'

Science.gov (United States)

site. Conference contact: Barbara Ferris, NREL, 1617 Cole Blvd., Golden, CO 80401. Phone: 303-275-3781 . E-mail Barbara Ferris. NREL is a national laboratory managed by Midwest Research Institute, Battelle

Improvement of the electrical contact resistance at rough interfaces using two dimensional materials

Energy Technology Data Exchange (ETDEWEB)

Hu, Jianchen; Pan, Chengbin; Lanza, Mario, E-mail: mlanza@suda.edu.cn [Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nanoscience and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123 (China); Li, Heng [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871 (China); CAPT, HEDPS and IFSA Collaborative Innovation Center of MoE, Peking University, Beijing 100871 (China); Shen, Panpan; Sun, Hui; Duan, Huiling [State Key Laboratory for Turbulence and Complex System, Department of Mechanics and Engineering Science, CAPT, College of Engineering, Peking University, Beijing 100871 (China)

2015-12-07

Reducing the electronic contact resistance at the interfaces of nanostructured materials is a major goal for many kinds of planar and three dimensional devices. In this work, we develop a method to enhance the electronic transport at rough interfaces by inserting a two dimensional flexible and conductive graphene sheet. We observe that an ultra-thin graphene layer with a thickness of 0.35 nm can remarkably reduce the roughness of a sample in a factor of 40%, avoiding the use of thick coatings, leading to a more homogeneous current flow, and extraordinarily increasing the total current compared to the graphene-free counterpart. Due to its simplicity and performance enhancement, this methodology can be of interest to many interface and device designers.

Novel Sn-Based Contact Structure for GeTe Phase Change Materials.

Science.gov (United States)

Simchi, Hamed; Cooley, Kayla A; Ding, Zelong; Molina, Alex; Mohney, Suzanne E

2018-05-16

Germanium telluride (GeTe) is a phase change material (PCM) that has gained recent attention because of its incorporation as an active material for radio frequency (RF) switches, as well as memory and novel optoelectronic devices. Considering PCM-based RF switches, parasitic resistances from Ohmic contacts can be a limiting factor in device performance. Reduction of the contact resistance ( R c ) is therefore critical for reducing the on-state resistance to meet the requirements of high-frequency RF applications. To engineer the Schottky barrier between the metal contact and GeTe, Sn was tested as an interesting candidate to alter the composition of the semiconductor near its surface, potentially forming a narrow band gap (0.2 eV) SnTe or a graded alloy with SnTe in GeTe. For this purpose, a novel contact stack of Sn/Fe/Au was employed and compared to a conventional Ti/Pt/Au stack. Two different premetallization surface treatments of HCl and deionized (DI) H 2 O were employed to make a Te-rich and Ge-rich interface, respectively. Contact resistance values were extracted using the refined transfer length method. The best results were obtained with DI H 2 O for the Sn-based contacts but HCl treatment for the Ti/Pt/Au contacts. The as-deposited contacts had the R c (ρ c ) of 0.006 Ω·mm (8 × 10 -9 Ω·cm 2 ) for Sn/Fe/Au and 0.010 Ω·mm (3 × 10 -8 Ω·cm 2 ) for Ti/Pt/Au. However, the Sn/Fe/Au contacts were thermally stable, and their resistance decreased further to 0.004 Ω·mm (4 × 10 -9 Ω·cm 2 ) after annealing at 200 °C. In contrast, the contact resistance of the Ti/Pt/Au stack increased to 0.012 Ω·mm (4 × 10 -8 Ω·cm 2 ). Transmission electron microscopy was used to characterize the interfacial reactions between the metals and GeTe. It was found that formation of SnTe at the interface, in addition to Fe diffusion (doping) into GeTe, is likely responsible for the superior performance of Sn/Fe/Au contacts, resulting in one of the lowest reported

Pentacene ohmic contact on the transparent conductive oxide films

International Nuclear Information System (INIS)

Chu, Jian-An; Zeng, Jian-Jhou; Wu, Kuo-Chen; Lin, Yow-Jon

2010-01-01

Low-resistance ohmic contacts are essential to improve the performance of pentacene-based electronic and optoelectronic devices. In this study, we reported ohmic contact formation at the indium tin oxide (ITO)/pentacene and indium cerium oxide (ICO)/pentacene interfaces. According to the observed results from current-voltage and Kelvin probe measurements, we found that the lower contact resistivity of the ICO/pentacene sample than the ITO/pentacene sample may be attributed to the higher surface work function of ICO than ITO.

31st IMAC Conference on Structural Dynamics

CERN Document Server

Adams, Douglas; Carrella, Alex; Mayes, Randy; Rixen, Daniel; Allen, Matt; Cunha, Alvaro; Catbas, Fikret; Pakzad, Shamim; Racic, Vitomir; Pavic, Aleksandar; Reynolds, Paul; Simmermacher, Todd; Cogan, Scott; Moaveni, Babak; Papadimitriou, Costas; Allemang, Randall; Clerck, James; Niezrecki, Christopher; Wicks, Alfred

2013-01-01

Topics in Nonlinear Dynamics, Volume 1: Proceedings of the 31st IMAC, A Conference and Exposition on Structural Dynamics, 2013, the first volume of seven from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Dynamics, including papers on:   Nonlinear Oscillations Nonlinearities In Practice Nonlinear System Identification: Methods Nonlinear System Identification: Friction & Contact Nonlinear Modal Analysis Nonlinear Modeling & Simulation Nonlinear Vibration Absorbers Constructive Utilization of Nonlinearity.

Novel resistance functions uncovered using functional metagenomic investigations of resistance reservoirs

Directory of Open Access Journals (Sweden)

Erica C. Pehrsson

2013-06-01

Full Text Available Rates of infection with antibiotic-resistant bacteria have increased precipitously over the past several decades, with far-reaching healthcare and societal costs. Recent evidence has established a link between antibiotic resistance genes in human pathogens and those found in non-pathogenic, commensal, and environmental organisms, prompting deeper investigation of natural and human-associated reservoirs of antibiotic resistance. Functional metagenomic selections, in which shotgun-cloned DNA fragments are selected for their ability to confer survival to an indicator host, have been increasingly applied to the characterization of many antibiotic resistance reservoirs. These experiments have demonstrated that antibiotic resistance genes are highly diverse and widely distributed, many times bearing little to no similarity to known sequences. Through unbiased selections for survival to antibiotic exposure, functional metagenomics can improve annotations by reducing the discovery of false-positive resistance and by allowing for the identification of previously unrecognizable resistance genes. In this review, we summarize the novel resistance functions uncovered using functional metagenomic investigations of natural and human-impacted resistance reservoirs. Examples of novel antibiotic resistance genes include those highly divergent from known sequences, those for which sequence is entirely unable to predict resistance function, bifunctional resistance genes, and those with unconventional, atypical resistance mechanisms. Overcoming antibiotic resistance in the clinic will require a better understanding of existing resistance reservoirs and the dissemination networks that govern horizontal gene exchange, informing best practices to limit the spread of resistance-conferring genes to human pathogens.

1st Large Hadron Collider Physics Conference

CERN Document Server

Juste, A; Martínez, M; Riu, I; Sorin, V

2013-01-01

The conference is the result of merging two series of international conferences, "Physics at Large Hadron Collider" (PLHC2012) and "Hadron Collider Physics Symposium" (HCP2012). With a program devoted to topics such as the Standard Model and Beyond, the Higgs Boson, Supersymmetry, Beauty and Heavy Ion Physics, the conference aims at providing a lively forum for discussion between experimenters and theorists of the latest results and of new ideas. LHCP 2013 will be hosted by IFAE (Institut de Fisica d'Altes Energies) in Barcelona (Spain), and will take place from May 13 to 18, 2013. The venue will be the Hotel Catalonia Plaza, Plaza España (Barcelona). More information will be posted soon. For questions, please contact lhcp2013@ifae.es.

Understanding the influence of tellurium oxide in front Ag paste for contacting silicon solar cells with homogeneous high sheet resistance emitter

Science.gov (United States)

Ebong, Abasifreke; Bezawada, Nirupama; Batchu, Kartheek

2017-08-01

This paper investigates TeO2, one of the front Ag paste additives, to understand its role in low contact and gridline resistances for screen-printed Si solar cell. It is concluded that TeO2 aids the reduction of molten glass frit viscosity during contact co-firing. This in turn, leads to uniform flow of molten glass frit, both in the gridline bulk and interface of gridline and SiN x . Therefore, the uniform wetting and etching of SiN x and consequently larger contact area of metal to Si compared to its counterpart without TeO2. Hence, the current transport mechanism from Si to gridline can be said to be both direct and tunneling. The Raman spectra showed a blue shift in the phase of the TeO2 after contact co-firing in the gridline bulk confirming a crystalline γ-TeO2.

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

The targeted inhibition of mitochondrial Hsp90 overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis

Energy Technology Data Exchange (ETDEWEB)

Yan, Chunlan [Department of Anatomy and Cell Biology, Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan, 602-714 (Korea, Republic of); Department of Physiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058 (China); Oh, Joon Seok; Yoo, Seung Hee; Lee, Jee Suk [Department of Anatomy and Cell Biology, Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan, 602-714 (Korea, Republic of); Yoon, Young Geol [Department of Anatomy and Cell Biology, Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan, 602-714 (Korea, Republic of); Department of Biomedical Science, Institute for Biomedical and Health Sciences, Jungwon University, Chungbuk, 367-805 (Korea, Republic of); Oh, Yoo Jin; Jang, Min Seok [Department of Anatomy and Cell Biology, Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan, 602-714 (Korea, Republic of); Lee, Sang Yeob [Department of Rheumatology, Dong-A University College of Medicine, Busan, 602-714 (Korea, Republic of); Yang, Jun [Department of Toxicology, Hangzhou Normal University School of Public Health, Hangzhou, Zhejiang, 310036 China (China); Lee, Sang Hwa [Department of Microbiology and, Dong-A University College of Medicine, Busan, 602-714 (Korea, Republic of); Kim, Hye Young [Department of Anatomy and Cell Biology, Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan, 602-714 (Korea, Republic of); Yoo, Young Hyun, E-mail: yhyoo@dau.ac.kr [Department of Anatomy and Cell Biology, Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan, 602-714 (Korea, Republic of)

2013-01-01

Previous studies have reported that a Gamitrinib variant containing triphenylphosphonium (G-TPP) binds to mitochondrial Hsp90 and rapidly inhibits its activity, thus inducing the apoptotic pathway in the cells. Accordingly, G-TPP shows a potential as a promising drug for the treatment of cancer. A cell can die from different types of cell death such as apoptosis, necrosis, necroptosis, and autophagic cell death. In this study, we further investigated the mechanisms and modes of cell death in the G-TPP-treated Hep3B and U937 cell lines. We discovered that G-TPP kills the U937 cells through the apoptotic pathway and the overexpression of Bcl-2 significantly inhibits U937 cell death to G-TPP. We further discovered that G-TPP kills the Hep3B cells by activating necroptosis in combination with the partial activation of caspase-dependent apoptosis. Importantly, G-TPP overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis. We also observed that G-TPP induces compensatory autophagy in the Hep3B cell line. We further found that whereas there is a Bcl-2-Beclin 1 interaction in response to G-TPP, silencing the beclin 1 gene failed to block LC3-II accumulation in the Hep3B cells, indicating that G-TPP triggers Beclin 1-independent protective autophagy in Hep3B cells. Taken together, these data reveal that G-TPP induces cell death through a combination of death pathways, including necroptosis and apoptosis, and overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis. These findings are important for the therapeutic exploitation of necroptosis as an alternative cell death program to bypass the resistance to apoptosis. Highlights: ► G-TPP binds to mitochondrial Hsp90. ► G-TPP induces apoptosis in U937 human leukemia cancer cells. ► G-TPP induces combination of death pathways in Hep3B cell. ► G-TPP overcomes the resistance conferred by Bcl-2 in Hep3B cells via necroptosis. ► G-TPP triggers Beclin 1-independent

Multiyear evaluation of the durability of the resistance conferred by Ma and RMia genes to Meloidogyne incognita in Prunus under controlled conditions.

Science.gov (United States)

Khallouk, Samira; Voisin, Roger; Portier, Ulysse; Polidori, Joël; Van Ghelder, Cyril; Esmenjaud, Daniel

2013-08-01

Root-knot nematodes (RKNs) (Meloidogyne spp.) are highly polyphagous pests that parasitize Prunus crops in Mediterranean climates. Breeding for RKN-resistant Prunus cultivars, as an alternative to the now-banned use of nematicides, is a real challenge, because the perennial nature of these trees increases the risk of resistance breakdown. The Ma plum resistance (R) gene, with a complete spectrum, and the RMia peach R gene, with a more restricted spectrum, both provide total control of Meloidogyne incognita, the model parthenogenetic species of the genus and the most important RKN in terms of economic losses. We investigated the durability of the resistance to this nematode conferred by these genes, comparing the results obtained with those for the tomato Mi-1 reference gene. In multiyear experiments, we applied a high and continuous nematode inoculum pressure by cultivating nematode-infested susceptible tomato plants with either Prunus accessions carrying Ma or RMia R genes, or with resistant tomato plants carrying the Mi-1 gene. Suitable conditions for Prunus development were achieved by carrying out the studies in a glasshouse, in controlled conditions allowing a short winter leaf fall and dormancy. We first assessed the plum accession 'P.2175', which is heterozygous for the Ma gene, in two successive 2-year evaluations, for resistance to two M. incognita isolates. Whatever the isolate used, no nematodes reproducing on P.2175 were detected, whereas galls and nematodes reproducing on tomato plants carrying Mi-1 were observed. In a second experiment with the most aggressive isolate, interspecific full-sib material (P.2175 × ['Garfi' almond × 'Nemared' peach]), carrying either Ma or RMia (from Nemared) or both (in the heterozygous state) or neither of these genes, was evaluated for 4 years. No virulent nematodes developed on Prunus spp. carrying R genes, whereas galling and virulent individuals were observed on Mi-1-resistant tomato plants. Thus, the resistance to

Multi-Material Front Contact for 19% Thin Film Solar Cells

Directory of Open Access Journals (Sweden)

Joop van Deelen

2016-02-01

Full Text Available The trade-off between transmittance and conductivity of the front contact material poses a bottleneck for thin film solar panels. Normally, the front contact material is a metal oxide and the optimal cell configuration and panel efficiency were determined for various band gap materials, representing Cu(In,GaSe2 (CIGS, CdTe and high band gap perovskites. Supplementing the metal oxide with a metallic copper grid improves the performance of the front contact and aims to increase the efficiency. Various front contact designs with and without a metallic finger grid were calculated with a variation of the transparent conductive oxide (TCO sheet resistance, scribing area, cell length, and finger dimensions. In addition, the contact resistance and illumination power were also assessed and the optimal thin film solar panel design was determined. Adding a metallic finger grid on a TCO gives a higher solar cell efficiency and this also enables longer cell lengths. However, contact resistance between the metal and the TCO material can reduce the efficiency benefit somewhat.

Mutation of Rv2887, a marR-like gene, confers Mycobacterium tuberculosis resistance to an imidazopyridine-based agent.

Science.gov (United States)

Winglee, Kathryn; Lun, Shichun; Pieroni, Marco; Kozikowski, Alan; Bishai, William

2015-11-01

Drug resistance is a major problem in Mycobacterium tuberculosis control, and it is critical to identify novel drug targets and new antimycobacterial compounds. We have previously identified an imidazo[1,2-a]pyridine-4-carbonitrile-based agent, MP-III-71, with strong activity against M. tuberculosis. In this study, we evaluated mechanisms of resistance to MP-III-71. We derived three independent M. tuberculosis mutants resistant to MP-III-71 and conducted whole-genome sequencing of these mutants. Loss-of-function mutations in Rv2887 were common to all three MP-III-71-resistant mutants, and we confirmed the role of Rv2887 as a gene required for MP-III-71 susceptibility using complementation. The Rv2887 protein was previously unannotated, but domain and homology analyses suggested it to be a transcriptional regulator in the MarR (multiple antibiotic resistance repressor) family, a group of proteins first identified in Escherichia coli to negatively regulate efflux pumps and other mechanisms of multidrug resistance. We found that two efflux pump inhibitors, verapamil and chlorpromazine, potentiate the action of MP-III-71 and that mutation of Rv2887 abrogates their activity. We also used transcriptome sequencing (RNA-seq) to identify genes which are differentially expressed in the presence and absence of a functional Rv2887 protein. We found that genes involved in benzoquinone and menaquinone biosynthesis were repressed by functional Rv2887. Thus, inactivating mutations of Rv2887, encoding a putative MarR-like transcriptional regulator, confer resistance to MP-III-71, an effective antimycobacterial compound that shows no cross-resistance to existing antituberculosis drugs. The mechanism of resistance of M. tuberculosis Rv2887 mutants may involve efflux pump upregulation and also drug methylation. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Electrical properties of aluminum contacts deposited by DC sputtering method for photovoltaic applications

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Krawczak Ewelina

2017-01-01

Full Text Available The use of aluminum contacts is common in the process of silicon solar cells production because of low contact resistivity. It has also a great importance in thin film technology for photovoltaics, especially in copper-indium-gallium-diselenide (CIGS devices. The final stage of CIGS cell production is the top contact deposition of high conductivity layer for lateral current collection. Such material has to be highly optically transparent as well. In order to make a contact, metal is deposited onto TCO layer with minimum shadowing to allow as much light as possible into device. The metal grid contact is being made by deposition of few microns of aluminum. The resistivity of the deposited material as well as resistance between the metal grid and TCO layer plays a great role in high quality solar cell production. This paper presents the results of four point probe conductivity analysis of Al thin films deposited by direct current (DC magnetron sputtering method. Influence of technological parameters of the Al deposition process on sheet resistance of deposited layers has been showed. In order to obtain the lowest resistivity of the thin contact layer, optimal set of sputtering parameters, i.e. power applied, deposition time and deposition pressure was found. The resistivity of the contact between two adjacent Al metal fingers deposited onto transparent conductive Al-doped zinc oxide film has been also examined.

Electrical properties of aluminum contacts deposited by DC sputtering method for photovoltaic applications

Science.gov (United States)

Krawczak, Ewelina; Gułkowski, Sławomir

2017-10-01

The use of aluminum contacts is common in the process of silicon solar cells production because of low contact resistivity. It has also a great importance in thin film technology for photovoltaics, especially in copper-indium-gallium-diselenide (CIGS) devices. The final stage of CIGS cell production is the top contact deposition of high conductivity layer for lateral current collection. Such material has to be highly optically transparent as well. In order to make a contact, metal is deposited onto TCO layer with minimum shadowing to allow as much light as possible into device. The metal grid contact is being made by deposition of few microns of aluminum. The resistivity of the deposited material as well as resistance between the metal grid and TCO layer plays a great role in high quality solar cell production. This paper presents the results of four point probe conductivity analysis of Al thin films deposited by direct current (DC) magnetron sputtering method. Influence of technological parameters of the Al deposition process on sheet resistance of deposited layers has been showed. In order to obtain the lowest resistivity of the thin contact layer, optimal set of sputtering parameters, i.e. power applied, deposition time and deposition pressure was found. The resistivity of the contact between two adjacent Al metal fingers deposited onto transparent conductive Al-doped zinc oxide film has been also examined.

Cellular expression of gH confers resistance to herpes simplex virus type-1 entry

International Nuclear Information System (INIS)

Scanlan, Perry M.; Tiwari, Vaibhav; Bommireddy, Susmita; Shukla, Deepak

2003-01-01

Entry of herpes simplex virus-1 (HSV-1) into cells requires a concerted action of four viral glycoproteins gB, gD, and gH-gL. Previously, cell surface expression of gD had been shown to confer resistance to HSV-1 entry. To investigate any similar effects caused by other entry glycoproteins, gB and gH-gL were coexpressed with Nectin-1 in Chinese hamster ovary (CHO) cells. Interestingly, cellular expression of gB had no effect on HSV-1(KOS) entry. In contrast, entry was significantly reduced in cells expressing gH-gL. This effect was further analyzed by expressing gH and gL separately. Cells expressing gL were normally susceptible, whereas gH-expressing cells were significantly resistant. Further experiments suggested that the gH-mediated interference phenomenon was not specific to any particular gD receptor and was also observed in gH-expressing HeLa cells. Moreover, contrary to a previous report, gL-independent cell surface expression of gH was detected in stably transfected CHO cells, possibly implicating cell surface gH in the interference phenomenon. Thus, taken together these findings indicate that cellular expression of gH interferes with HSV-1 entry

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

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,

Effects of nanoscale coatings on reliability of MEMS ohmic contact switches

Science.gov (United States)

Tremper, Amber Leigh

This thesis examines how the electrical and mechanical behavior of Au thin films is altered by the presence of ultra-thin metallic coatings. To examine the mechanical behavior, nanoindentation, nano-scratch, and atomic force microscopy (AFM) testing was performed. The electrical behavior was evaluated through Kelvin probe contact resistance measurements. This thesis shows that ultra-thin, hard, ductile coatings on a softer, ductile underlying layer (such as Ru or Pt on Au) had a significant effect on mechanical behavior of the system, and can be tailored to control the deformation resistance of the thin film system. Despite Ru and Pt having a higher hardness and plane strain modulus than Au, the Ru and Pt coatings decreased both the hardness and plane strain modulus of the layered system when the indentation depth was on the order of the coating thickness. Alternately, when the indentation depth was several times the coating thickness, the ductile, plastically hard, elastically stiff layer significantly hardened the contact response. These results correlate well with membrane stress theoretical predictions, and demonstrate that membrane theory can be applied even when the ratio of indentation depth, h, to coating thickness, t, is very large ( h/telectrical behavior of the Ru-coated Au films was examined, it was found that all the measured resistances of the Au-only film and Ru-coated systems were several orders of magnitude larger than those predicted by Holm's law, but were still in good agreement with previously reported values in the literature. Previous studies attributed the high contact resistances to a variety of causes, including the buildup of an insulating contamination layer. This thesis determined the cause of the deviations to be large sheet resistance contributions to the total measured resistance. Further, studies on aged samples (with thicker contamination layers) conclusively showed that, while contamination increases the contact resistance, it

Dissection of two soybean QTL conferring partial resistance to Phytophthora sojae through sequence and gene expression analysis

Directory of Open Access Journals (Sweden)

Wang Hehe

2012-08-01

Full Text Available Abstract Background Phytophthora sojae is the primary pathogen of soybeans that are grown on poorly drained soils. Race-specific resistance to P. sojae in soybean is gene-for-gene, although in many areas of the US and worldwide there are populations that have adapted to the most commonly deployed resistance to P. sojae ( Rps genes. Hence, this system has received increased attention towards identifying mechanisms and molecular markers associated with partial resistance to this pathogen. Several quantitative trait loci (QTL have been identified in the soybean cultivar ‘Conrad’ that contributes to the expression of partial resistance to multiple P. sojae isolates. Results In this study, two of the Conrad QTL on chromosome 19 were dissected through sequence and expression analysis of genes in both resistant (Conrad and susceptible (‘Sloan’ genotypes. There were 1025 single nucleotide polymorphisms (SNPs in 87 of 153 genes sequenced from Conrad and Sloan. There were 304 SNPs in 54 genes sequenced from Conrad compared to those from both Sloan and Williams 82, of which 11 genes had SNPs unique to Conrad. Eleven of 19 genes in these regions analyzed with qRT-PCR had significant differences in fold change of transcript abundance in response to infection with P. sojae in lines with QTL haplotype from the resistant parent compared to those with the susceptible parent haplotype. From these, 8 of the 11 genes had SNPs in the upstream, untranslated region, exon, intron, and/or downstream region. These 11 candidate genes encode proteins potentially involved in signal transduction, hormone-mediated pathways, plant cell structural modification, ubiquitination, and basal resistance. Conclusions These findings may indicate a complex defense network with multiple mechanisms underlying these two soybean QTL conferring resistance to P. sojae. SNP markers derived from these candidate genes can contribute to fine mapping of QTL and marker assisted breeding for

77 FR 42257 - General Conference Committee of the National Poultry Improvement Plan; Solicitation for Membership

Science.gov (United States)

2012-07-18

...] General Conference Committee of the National Poultry Improvement Plan; Solicitation for Membership AGENCY... regional membership for the General Conference Committee of the National Poultry Improvement Plan. DATES... INFORMATION CONTACT: Dr. C. Stephen Roney, Senior Coordinator, National Poultry Improvement Plan, VS, APHIS...

Role of aluminum in silver paste contact to boron-doped silicon emitters

Directory of Open Access Journals (Sweden)

Wei Wu

2017-01-01

Full Text Available The addition of aluminum to silver metallization pastes has been found to lower the contact resistivity of a silver metallization on boron-doped silicon emitters for n-type Si solar cells. However, the addition of Al also induces more surface recombination and increases the Ag pattern′s line resistivity, both of which ultimately limit the cell efficiency. There is a need to develop a fundamental understanding of the role that Al plays in reducing the contact resistivity and to explore alternative additives. A fritless silver paste is used to allow direct analysis of the impact of Al on the Ag-Si interfacial microstructure and isolate the influence of Al on the electrical contact from the complicated Ag-Si interfacial glass layer. Electrical analysis shows that in a simplified system, Al decreases the contact resistivity by about three orders of magnitude. Detailed microstructural studies show that in the presence of Al, microscale metallic spikes of Al-Ag alloy and nanoscale metallic spikes of Ag-Si alloy penetrate the surface of the boron-doped Si emitters. These results demonstrate the role of Al in reducing the contact resistivity through the formation of micro- and nano-scale metallic spikes, allowing the direct contact to the emitters.

World Biotechnology Leaders to Gather for Conference

Science.gov (United States)

Biotechnology Leaders to Gather for Conference For more information contact: e:mail: Public Affairs biotechnology leaders gather in Fort Collins, CO May 2-6 for the 21st Symposium on Biotechnology for Fuels and special session on funding opportunities for U.S. biotechnology projects. More than 175 presentations are

Effects of junction resistance and counterelectrode material on point-contact tunneling into single- and polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-y/

Energy Technology Data Exchange (ETDEWEB)

Moog, E.R.; Hawley, M.E.; Gray, K.E.; Liu, J.Z.; Hinks, D.G.; Capone, D.W. II; Downey, J.

1988-06-01

The effects of junction resistance and counterelectrode material on the results of point-contact tunneling studies into single- and polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-y/ are illustrated. Although reasonably symmetric I(V) curves predominantly indicate energy gap values /Delta/ /approx/ 20 meV, large asymmetries are often found for high-resistance junctions. Very low-resistance junctions show the expected behavior of pure metallic bridge and indicate /Delta/ /approx/ 25-30 meV.

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.

Application and analysis of palladium vapor deposited on stainless steel for high temperature electrical contacts

International Nuclear Information System (INIS)

Jodeh, S.

2008-01-01

Using electron beam evaporation. Pd thin films of 300 nm thickness have been deposited on 301 stainless steel for high temperature electrical contact studies. The structure and compost ion of the helms were studied in detail x-ray diffraction (XRD), scanning electron microscopy (Sem), electron probe microanalysis (EPMA), and x-ray photoelectron spectroscopy (XP S) with sputter depth profiling. The contact properties such as contact resistance, fretting wear resistance, and thermal stability have been measured.The contact resistance rem ins low after heat-aging in air for 168 h at 150 and 200 deg., but increases significantly after heat-aging at 340 deg.. This increase in contact resistance is caused by the formation of about a 27 nm (1 μin.) thick Pdo. In contrast, the thickness of the Pdo is too thin to cause measurable contact resistance increases after heat-aging at 150 and 200 deg.. The fretting wear resistance of Pd coated 301 stainless steel is better than that of electroplated Sn of ser veal thousand nm thickness. Thus, vapor deposited Pd coating on 301 stainless steel may replace electroplated Sn for electrical contact application at elevated temperatures.

Phloem-specific expression of the lectin gene from Allium sativum confers resistance to the sap-sucker Nilaparvata lugens.

Science.gov (United States)

Chandrasekhar, Kottakota; Vijayalakshmi, Muvva; Vani, Kalasamudramu; Kaul, Tanushri; Reddy, Malireddy K

2014-05-01

Rice production is severely hampered by insect pests. Garlic lectin gene (ASAL) holds great promise in conferring protection against chewing (lepidopteran) and sap-sucking (homopteran) insect pests. We have developed transgenic rice lines resistant to sap-sucking brown hopper (Nilaparvata lugens) by ectopic expression of ASAL in their phloem tissues. Molecular analyses of T0 lines confirmed stable integration of transgene. T1 lines (NP 1-2, 4-3, 11-6 & 17-7) showed active transcription and translation of ASAL transgene. ELISA revealed ASAL expression was as high as 0.95% of total soluble protein. Insect bioassays on T2 homozygous lines (NP 18 & 32) revealed significant reduction (~74-83%) in survival rate, development and fecundity of brown hoppers in comparison to wild type. Transgenics exhibited enhanced resistance (1-2 score) against brown hoppers, minimal plant damage and no growth penalty or phenotypic abnormalities.

XA23 is an executor R protein and confers broad-spectrum disease resistance in rice.

Science.gov (United States)

Wang, Chunlian; Zhang, Xiaoping; Fan, Yinglun; Gao, Ying; Zhu, Qinlong; Zheng, Chongke; Qin, Tengfei; Li, Yanqiang; Che, Jinying; Zhang, Mingwei; Yang, Bing; Liu, Yaoguang; Zhao, Kaijun

2014-11-09

The majority of plant disease resistance (R) genes encode proteins that share common structural features. However, the transcription activator-like effector (TALE) associated executor type R genes show no considerable sequence homology to any known R genes. We adopted a map-based cloning approach and TALE-based technology to isolate and characterize Xa23, a new executor R gene derived from the wild rice (Oryza rufipogon) that confers an extremely broad spectrum of resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo). Xa23 encodes a 113-amino acid protein that shares 50% identity to the known executor R protein XA10. The predicted transmembrane helices in XA23 also overlap with those of XA10. Unlike Xa10, however, Xa23 transcription is specifically activated by AvrXa23, a TALE present in all examined Xoo field isolates. Moreover, the susceptible xa23 allele has an identical open reading frame of Xa23, but differs in promoter region by lacking the TALE binding-element (EBE) for AvrXa23. XA23 can trigger strong hypersensitive response in rice, tobacco and tomato. Our results provide the first evidence that plant genomes have an executor R gene family in which members execute their function and spectrum of disease resistance by recognizing the cognate TALEs in pathogen. © The Author 2014. Published by the Molecular Plant Shanghai Editorial Office in association with Oxford University Press on behalf of CSPB and IPPE, SIBS, CAS.

On a two-layer Si_3N_4/SiO_2 dielectric mask for low-resistance ohmic contacts to AlGaN/GaN HEMTs

International Nuclear Information System (INIS)

Arutyunyan, S. S.; Pavlov, A. Yu.; Pavlov, B. Yu.; Tomosh, K. N.; Fedorov, Yu. V.

2016-01-01

The fabrication of a two-layer Si_3N_4/SiO_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_3N_4/SiO_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.

Thermal stability of Ni/Ti/Al ohmic contacts to p-type 4H-SiC

Energy Technology Data Exchange (ETDEWEB)

Yu, Hailong; Shen, Huajun, E-mail: shenhuajun@ime.ac.cn; Tang, Yidan; Bai, Yun; Liu, Xinyu [Microwave Device and IC Department, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); Zhang, Xufang [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wu, Yudong; Liu, Kean [Zhuzhou CSR Times Electric Co., Ltd, ZhuZhou 412001 (China)

2015-01-14

Low resistivity Ni/Ti/Al ohmic contacts on p-type 4H-SiC epilayer were developed, and their thermal stabilities were also experimentally investigated through high temperature storage at 600 °C for 100 h. The contact resistance of the Al/Ti/Ni/SiC contacts degraded in different degrees, and the contact morphology deteriorated with the increases of the average surface roughness and interface voids. X-ray spectra showed that Ni{sub 2}Si and Ti{sub 3}SiC{sub 2}, which were formed during ohmic contact annealing and contributed to low contact resistivity, were stable under high temperature storage. The existence of the TiAl{sub 3} and NiAl{sub 3} intermetallic phases was helpful to prevent Al agglomeration on the interface and make the contacts thermally stable. Auger electron spectroscopy indicated that the incorporation of oxygen at the surface and interface led to the oxidation of Al or Ti resulting in increased contact resistance. Also, the formation of these oxides roughened the surface and interface. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism dominates the current transport for contacts before and after the thermal treatment. It suggests that the Ni/Ti/Al composite ohmic contacts are promising for SiC devices to be used in high temperature applications.

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.

Influence factors and temperature reliability of ohmic contact on AlGaN/GaN HEMTs

Directory of Open Access Journals (Sweden)

Liang Song

2018-03-01

Full Text Available In this paper, we have studied the performance of Ti/Al/Ni/Au ohmic contact with different Al and Au thicknesses and pretreatments. The temperature dependence of contact resistances (Rc was investigated and it shows that there are different optimal annealing temperatures with different metal thicknesses and pretreatments. The optimal annealing temperature is affected by Al and Au thickness and AlGaN thickness. The etched AlGaN barrier is useful to achieve good ohmic contact (0.24 Ω·mm with a low annealing temperature. Only the contact resistances of the samples with 130 nm Al layer kept stable and the contact resistances of the samples with 100nm and 160 nm Al layers increased with the measurement temperatures. The contact resistances showed a similar increase and then keep stable trend for all the samples in the long-term 400 °C aging process. The ohmic metal of 20/130/50/50 nm Ti/Al/Ni/Au with ICP etching is the superior candidate considering the contact resistance and reliability.

MHC class I Dk locus and Ly49G2+ NK cells confer H-2k resistance to murine cytomegalovirus.

Science.gov (United States)

Xie, Xuefang; Stadnisky, Michael D; Brown, Michael G

2009-06-01

Essential NK cell-mediated murine CMV (MCMV) resistance is under histocompatibility-2(k) (H-2(k)) control in MA/My mice. We generated a panel of intra-H2(k) recombinant strains from congenic C57L.M-H2(k/b) (MCMV resistant) mice for precise genetic mapping of the critical interval. Recombination breakpoint sites were precisely mapped and MCMV resistance/susceptibility traits were determined for each of the new lines to identify the MHC locus. Strains C57L.M-H2(k)(R7) (MCMV resistant) and C57L.M-H2(k)(R2) (MCMV susceptible) are especially informative; we found that allelic variation in a 0.3-megabase interval in the class I D locus confers substantial difference in MCMV control phenotypes. When NK cell subsets responding to MCMV were examined, we found that Ly49G2(+) NK cells rapidly expand and selectively acquire an enhanced capacity for cytolytic functions only in C57L.M-H2(k)(R7). We further show that depletion of Ly49G2(+) NK cells before infection abrogated MCMV resistance in C57L.M-H2(k)(R7). We conclude that the MHC class I D locus prompts expansion and activation of Ly49G2(+) NK cells that are needed in H-2(k) MCMV resistance.

Electroplated contacts and porous silicon for silicon based solar cells applications

Energy Technology Data Exchange (ETDEWEB)

Kholostov, Konstantin, E-mail: kholostov@diet.uniroma1.it [Department of information engineering, electronics and telecommunications, University of Rome “La Sapienza”, Via Eudossiana 18, 00184 Rome (Italy); Serenelli, Luca; Izzi, Massimo; Tucci, Mario [Enea Casaccia Research Centre Rome, via Anguillarese 301, 00123 Rome (Italy); Balucani, Marco [Department of information engineering, electronics and telecommunications, University of Rome “La Sapienza”, Via Eudossiana 18, 00184 Rome (Italy); Rise Technology S.r.l., Lungomare Paolo Toscanelli 170, 00121 Rome (Italy)

2015-04-15

Highlights: • Uniformity of the Ni–Si interface is crucial for performance of Cu–Ni contacts on Si. • Uniformly filled PS is the key to obtain the best performance of Cu–Ni contacts on Si. • Optimization of anodization and electroplating allows complete filling of PS layer. • Highly adhesive and low contact resistance Cu–Ni contacts are obtained on Si. - Abstract: In this paper, a two-layer metallization for silicon based solar cells is presented. The metallization consists of thin nickel barrier and thick copper conductive layers, both obtained by electrodeposition technique suitable for phosphorus-doped 70–90 Ω/sq solar cell emitter formed on p-type silicon substrate. To ensure the adhesion between metal contact and emitter a very thin layer of mesoporous silicon is introduced on the emitter surface before metal deposition. This approach allows metal anchoring inside pores and improves silicon–nickel interface uniformity. Optimization of metal contact parameters is achieved varying the anodization and electrodeposition conditions. Characterization of contacts between metal and emitter is carried out by scanning electron microscopy, specific contact resistance and current–voltage measurements. Mechanical strength of nickel–copper contacts is evaluated by the peel test. Adhesion strength of more than 4.5 N/mm and contact resistance of 350 μΩ cm{sup 2} on 80 Ω/sq emitter are achieved.

Expression of a radish defensin in transgenic wheat confers increased resistance to Fusarium graminearum and Rhizoctonia cerealis.

Science.gov (United States)

Li, Zhao; Zhou, Miaoping; Zhang, Zengyan; Ren, Lijuan; Du, Lipu; Zhang, Boqiao; Xu, Huijun; Xin, Zhiyong

2011-03-01

Fusarium head blight (scab), primarily caused by Fusarium graminearum, is a devastating disease of wheat (Triticum aestivum L.) worldwide. Wheat sharp eyespot, mainly caused by Rhizoctonia cerealis, is one of the major diseases of wheat in China. The defensin RsAFP2, a small cyteine-rich antifungal protein from radish (Raphanus sativus), was shown to inhibit growth in vitro of agronomically important fungal pathogens, such as F. graminearum and R. cerealis. The RsAFP2 gene was transformed into Chinese wheat variety Yangmai 12 via biolistic bombardment to assess the effectiveness of the defensin in protecting wheat from the fungal pathogens in multiple locations and years. The genomic PCR and Southern blot analyses indicated that RsAFP2 was integrated into the genomes of the transgenic wheat lines and heritable. RT-PCR and Western blot proved that the RsAFP2 was expressed in these transgenic wheat lines. Disease tests showed that four RsAFP2 transgenic lines (RA1-RA4) displayed enhanced resistance to F. graminearum compared to the untransformed Yangmai 12 and the null-segregated plants. Assays on Q-RT-PCR and disease severity showed that the express level of RsAFP2 was associated with the enhanced resistance degree. Two of these transgenic lines (RA1 and RA2) also exhibited enhanced resistance to R. cerealis. These results indicated that the expression of RsAFP2 conferred increased resistance to F. graminearum and R. cerealis in transgenic wheat.

Continuous control systems for non-contact ECG

Science.gov (United States)

Kodkin, Vladimir L.; Yakovleva, Galina V.; Smirnov, Alexey S.

2017-03-01

South Ural State University is still conducting the research work dedicated to innovations in biomedicine. Development of system for continuous control and diagnosis of the functional state in large groups of people is based on studies of non-contact ECG recording reported by the authors at the SPIE conference in 2016. The next stage of studies has been performed this year.

Investigation of aluminium ohmic contacts to n-type GaN grown by molecular beam epitaxy

Science.gov (United States)

Kribes, Y.; Harrison, I.; Tuck, B.; Kim, K. S.; Cheng, T. S.; Foxon, C. T.

1997-11-01

Using epi-layers of different doping concentrations, we have investigated aluminium contacts on n-type gallium nitride grown by plasma source molecular beam epitaxy. To achieve repeatable and reliable results it was found that the semiconductor needed to be etched in aqua-regia before the deposition of the contact metallization. Scanning electron micrographs of the semiconductor surface show a deterioration of the semiconductor surface on etching. The specific contact resistivity of the etched samples were, however, superior. Annealing the contacts at 0268-1242/12/11/030/img9 produced contacts with the lowest specific contact resistance of 0268-1242/12/11/030/img10. The long-term aging of these contacts was also investigated. The contacts and the sheet resistance were both found to deteriorate over a three-month period.

AlGaN channel field effect transistors with graded heterostructure ohmic contacts

Science.gov (United States)

Bajaj, Sanyam; Akyol, Fatih; Krishnamoorthy, Sriram; Zhang, Yuewei; Rajan, Siddharth

2016-09-01

We report on ultra-wide bandgap (UWBG) Al0.75Ga0.25N channel metal-insulator-semiconductor field-effect transistors (MISFETs) with heterostructure engineered low-resistance ohmic contacts. The low intrinsic electron affinity of AlN (0.6 eV) leads to large Schottky barriers at the metal-AlGaN interface, resulting in highly resistive ohmic contacts. In this work, we use a reverse compositional graded n++ AlGaN contact layer to achieve upward electron affinity grading, leading to a low specific contact resistance (ρsp) of 1.9 × 10-6 Ω cm2 to n-Al0.75Ga0.25N channels (bandgap ˜5.3 eV) with non-alloyed contacts. We also demonstrate UWBG Al0.75Ga0.25N channel MISFET device operation employing the compositional graded n++ ohmic contact layer and 20 nm atomic layer deposited Al2O3 as the gate-dielectric.

Artemisinin-resistant malaria: research challenges, opportunities, and public health implications.

Science.gov (United States)

Fairhurst, Rick M; Nayyar, Gaurvika M L; Breman, Joel G; Hallett, Rachel; Vennerstrom, Jonathan L; Duong, Socheat; Ringwald, Pascal; Wellems, Thomas E; Plowe, Christopher V; Dondorp, Arjen M

2012-08-01

Artemisinin-based combination therapies are the most effective drugs to treat Plasmodium falciparum malaria. Reduced sensitivity to artemisinin monotherapy, coupled with the emergence of parasite resistance to all partner drugs, threaten to place millions of patients at risk of inadequate treatment of malaria. Recognizing the significance and immediacy of this possibility, the Fogarty International Center and the National Institute of Allergy and Infectious Diseases of the U.S. National Institutes of Health convened a conference in November 2010 to bring together the diverse array of stakeholders responding to the growing threat of artemisinin resistance, including scientists from malarious countries in peril. This conference encouraged and enabled experts to share their recent unpublished data from studies that may improve our understanding of artemisinin resistance. Conference sessions addressed research priorities to forestall artemisinin resistance and fostered collaborations between field- and laboratory-based researchers and international programs, with the aim of translating new scientific evidence into public health solutions. Inspired by this conference, this review summarizes novel findings and perspectives on artemisinin resistance, approaches for translating research data into relevant public health information, and opportunities for interdisciplinary collaboration to combat artemisinin resistance.

Microbiology: Barriers to the spread of resistance

DEFF Research Database (Denmark)

Sommer, Morten

2014-01-01

Despite identifying abundant genes capable of conferring antibiotic resistance in soil microorganisms, a study finds that few are shared by human pathogens and that there is little transfer of the genes within the soil communities.......Despite identifying abundant genes capable of conferring antibiotic resistance in soil microorganisms, a study finds that few are shared by human pathogens and that there is little transfer of the genes within the soil communities....

Thermal conductivity of a graphite bipolar plate (BPP) and its thermal contact resistance with fuel cell gas diffusion layers: Effect of compression, PTFE, micro porous layer (MPL), BPP out-of-flatness and cyclic load

Science.gov (United States)

Sadeghifar, Hamidreza; Djilali, Ned; Bahrami, Majid

2015-01-01

This paper reports on measurements of thermal conductivity of a graphite bipolar plate (BPP) as a function of temperature and its thermal contact resistance (TCR) with treated and untreated gas diffusion layers (GDLs). The thermal conductivity of the BPP decreases with temperature and its thermal contact resistance with GDLs, which has been overlooked in the literature, is found to be dominant over a relatively wide range of compression. The effects of PTFE loading, micro porous layer (MPL), compression, and BPP out-of-flatness are also investigated experimentally. It is found that high PTFE loadings, MPL and even small BPP out-of-flatness increase the BPP-GDL thermal contact resistance dramatically. The paper also presents the effect of cyclic load on the total resistance of a GDL-BPP assembly, which sheds light on the behavior of these materials under operating conditions in polymer electrolyte membrane fuel cells.

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.

Cellular robustness conferred by genetic crosstalk underlies resistance against chemotherapeutic drug doxorubicin in fission yeast.

Directory of Open Access Journals (Sweden)

Zoey Tay

Full Text Available Doxorubicin is an anthracycline antibiotic that is among one of the most commonly used chemotherapeutic agents in the clinical setting. The usage of doxorubicin is faced with many problems including severe side effects and chemoresistance. To overcome these challenges, it is important to gain an understanding of the underlying molecular mechanisms with regards to the mode of action of doxorubicin. To facilitate this aim, we identified the genes that are required for doxorubicin resistance in the fission yeast Schizosaccharomyces pombe. We further demonstrated interplay between factors controlling various aspects of chromosome metabolism, mitochondrial respiration and membrane transport. In the nucleus we observed that the subunits of the Ino80, RSC, and SAGA complexes function in the similar epistatic group that shares significant overlap with the homologous recombination genes. However, these factors generally act in synergistic manner with the chromosome segregation regulator DASH complex proteins, possibly forming two major arms for regulating doxorubicin resistance in the nucleus. Simultaneous disruption of genes function in membrane efflux transport or the mitochondrial respiratory chain integrity in the mutants defective in either Ino80 or HR function resulted in cumulative upregulation of drug-specific growth defects, suggesting a rewiring of pathways that synergize only when the cells is exposed to the cytotoxic stress. Taken together, our work not only identified factors that are required for survival of the cells in the presence of doxorubicin but has further demonstrated that an extensive molecular crosstalk exists between these factors to robustly confer doxorubicin resistance.

The 2nd International Conference on Particle Physics and Astrophysics

CERN Document Server

Soldatov, Evgeny; ICPPA 2016

2016-01-01

The 2nd International Conference on Particle Physics and Astrophysics (ICPPA-2016) will be held in Moscow, Russia, (from the 10th to 14th of October). The conference is organized by the National Research Nuclear University “MEPhI”. The aim of the Conference is to promote contacts between scientists and to develop new ideas in fundamental research. Therefore we will bring together experts and young scientists working in experimental and theoretical aspects of nuclear physics, particle physics (including astroparticle physics), and cosmology. ICPPA-2016 aims to present the most recent results in astrophysics and collider physics from the main experiments actively taking data as well as any upgrades for the methods of experimental particle physics. Furthermore, one special workshop will be held within the framework of this conference: «SiPM development and application». The working language of the conference is English

Recognition elements in rRNA for the tylosin resistance methyltransferase RlmA(II)

DEFF Research Database (Denmark)

Lebars, Isabelle; Husson, Clotilde; Yoshizawa, Satoko

2007-01-01

The methyltransferase RlmA(II) (formerly TlrB) is found in many Gram-positive bacteria, and methylates the N-1 position of nucleotide G748 within the loop of hairpin 35 in 23S rRNA. Methylation of the rRNA by RlmA(II) confers resistance to tylosin and other mycinosylated 16-membered ring macrolide......RNA substrate indicated that multiple contacts occur between RlmA(II) and nucleotides in stem-loops 33, 34 and 35. RlmA(II) appears to recognize its rRNA target through specific surface shape complementarity at the junction formed by these three helices. This means of recognition is highly similar...

Evaluation of Tire/Surfacing/Base Contact Stresses and Texture Depth

Directory of Open Access Journals (Sweden)

W.J.vdM. Steyn

2015-03-01

Full Text Available Tire rolling resistance has a major impact on vehicle fuel consumption. Rolling resistance is the loss of energy due to the interaction between the tire and the pavement surface. This interaction is a complicated combination of stresses and strains which depend on both tire and pavement related factors. These include vehicle speed, vehicle weight, tire material and type, road camber, tire inflation pressure, pavement surfacing texture etc. In this paper the relationship between pavement surface texture depth and tire/surfacing contact stress and area is investigated. Texture depth and tire/surfacing contact stress were measured for a range of tire inflation pressures on five different pavement surfaces. In the analysis the relationship between texture and the generated contact stresses as well as the contact stress between the surfacing and base layer are presented and discussed, and the anticipated effect of these relationships on the rolling resistance of vehicles on the surfacings, and subsequent vehicle fuel economy discussed.

Conference Offers Girls Opportunity to Expand Career Horizons

Science.gov (United States)

Offers Girls Opportunity to Expand Career Horizons For more information contact: e:mail: Public Affairs Golden, Colo., Feb. 11, 1997 -- Expanding Your Horizons, a conference for girls grades 6 - 9 and Employed Women, Girls Incorporated of Metro Denver, King Soopers, McDonalds, the TCI Adult Program and the

NATO Conference on Manpower Planning and Organization Design

CERN Document Server

Niehaus, Richard

1978-01-01

This volume is the proceedings of the conference entitled "Manpower Planning and Organization Design" which was held in Stresa, Italy, 20-24 June 1977. The Conference was sponsored by the NATO Scientific Affairs Division and organized jointly through the Special Programs Panels on Human Factors and on Systems Science. Two Conference Directors were appointed with overall responsibilities for the programme and for policy, and they were assisted in their tasks by a small advisory panel consisting of Professor A. Charnes (University of Texas), Professor W.W. Cooper (Carnegie Mellon University, now at Harvard University) and Dr. F.A. Heller (TavistQck Institute of Human Relations). Professor R. Florio of Bergamo kindly agreed to become Administrative Director and, as such, was responsible for all the local arrangements. The Conference Directors were further assisted by "national points of contact" appointed from each of the member countries of NATO. These national representatives played a substantial part in the s...

Expression of self-complementary hairpin RNA under the control of the rolC promoter confers systemic disease resistance to plum pox virus without preventing local infection.

Science.gov (United States)

Pandolfini, Tiziana; Molesini, Barbara; Avesani, Linda; Spena, Angelo; Polverari, Annalisa

2003-06-25

Homology-dependent selective degradation of RNA, or post-transcriptional gene silencing (PTGS), is involved in several biological phenomena, including adaptative defense mechanisms against plant viruses. Small interfering RNAs mediate the selective degradation of target RNA by guiding a multicomponent RNAse. Expression of self-complementary hairpin RNAs within two complementary regions separated by an intron elicits PTGS with high efficiency. Plum pox virus (PPV) is the etiological agent of sharka disease in Drupaceae, although it can also be transmitted to herbaceous species (e.g. Nicotiana benthamiana). Once inside the plant, PPV is transmitted via plasmodesmata from cell to cell, and at longer distances, via phloem. The rolC promoter drives expression in phloem cells. RolC expression is absent in both epidermal and mesophyll cells. The aim of the present study was to confer systemic disease resistance without preventing local viral infection. In the ihprolC-PP197 gene (intron hair pin rolC PPV 197), a 197 bp sequence homologous to the PPV RNA genome (from base 134 to 330) was placed as two inverted repeats separated by the DNA sequence of the rolA intron. This hairpin construct is under the control of the rolC promoter.N. benthamiana plants transgenic for the ihprolC-PP197 gene contain siRNAs homologous to the 197 bp sequence. The transgenic progeny of ihprolC-PP197 plants are resistant to PPV systemic infection. Local infection is unaffected. Most (80%) transgenic plants are virus free and symptomless. Some plants (20%) contain virus in uninoculated apical leaves; however they show only mild symptoms of leaf mottling. PPV systemic resistance cosegregates with the ihprolC-PP197 transgene and was observed in progeny plants of all independent transgenic lines analyzed. SiRNAs of 23-25 nt homologous to the PPV sequence used in the ihprolC-PP197 construct were detected in transgenic plants before and after inoculation. Transitivity of siRNAs was observed in

Stable integration and expression of a cry1Ia gene conferring resistance to fall armyworm and boll weevil in cotton plants.

Science.gov (United States)

Silva, Carliane Rc; Monnerat, Rose; Lima, Liziane M; Martins, Érica S; Melo Filho, Péricles A; Pinheiro, Morganna Pn; Santos, Roseane C

2016-08-01

Boll weevil is a serious pest of cotton crop. Effective control involves applications of chemical insecticides, increasing the cost of production and environmental pollution. The current genetically modified Bt crops have allowed great benefits to farmers but show activity limited to lepidopteran pests. This work reports on procedures adopted for integration and expression of a cry transgene conferring resistance to boll weevil and fall armyworm by using molecular tools. Four Brazilian cotton cultivars were microinjected with a minimal linear cassette generating 1248 putative lines. Complete gene integration was found in only one line (T0-34) containing one copy of cry1Ia detected by Southern blot. Protein was expressed in high concentration at 45 days after emergence (dae), decreasing by approximately 50% at 90 dae. Toxicity of the cry protein was demonstrated in feeding bioassays revealing 56.7% mortality to boll weevil fed buds and 88.1% mortality to fall armyworm fed leaves. A binding of cry1Ia antibody was found in the midgut of boll weevils fed on T0-34 buds in an immunodetection assay. The gene introduced into plants confers resistance to boll weevil and fall armyworm. Transmission of the transgene occurred normally to T1 progeny. All plants showed phenotypically normal growth, with fertile flowers and abundant seeds. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

The diversity of antimicrobial resistance genes among staphylococci of animal origin.

Science.gov (United States)

Wendlandt, Sarah; Feßler, Andrea T; Monecke, Stefan; Ehricht, Ralf; Schwarz, Stefan; Kadlec, Kristina

2013-08-01

Staphylococci of animal origin harbor a wide variety of resistance genes. So far, more than 40 different resistance genes have been identified in staphylococci from animals. This includes genes that confer resistance to virtually all classes of antimicrobial agents approved for use in animals, such as penicillins, cephalosporins, tetracyclines, macrolides, lincosamides, phenicols, aminoglycosides, aminocyclitols, pleuromutilins, and diaminopyrimidines. The gene products of some of these resistance genes confer resistance to only specific members of a class of antimicrobial agents, whereas others confer resistance to the entire class or even to members of different classes of antimicrobial agents. The resistance mechanisms specified by the resistance genes fall into three major categories: (i) enzymatic inactivation, (ii) active efflux, or (iii) protection/modification/replacement of the cellular target sites of the antimicrobial agents. Mobile genetic elements, in particular plasmids and transposons, play a major role as carriers of antimicrobial resistance genes in animal staphylococci. They facilitate the exchange of resistance genes with staphylococci of human origin but also with other Gram-positive bacteria. Copyright © 2013 Elsevier GmbH. All rights reserved.

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

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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.

Herbicide resistance-endowing ACCase gene mutations in hexaploid wild oat (Avena fatua): insights into resistance evolution in a hexaploid species

Science.gov (United States)

Yu, Q; Ahmad-Hamdani, M S; Han, H; Christoffers, M J; Powles, S B

2013-01-01

Many herbicide-resistant weed species are polyploids, but far too little about the evolution of resistance mutations in polyploids is understood. Hexaploid wild oat (Avena fatua) is a global crop weed and many populations have evolved herbicide resistance. We studied plastidic acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicide resistance in hexaploid wild oat and revealed that resistant individuals can express one, two or three different plastidic ACCase gene resistance mutations (Ile-1781-Leu, Asp-2078-Gly and Cys-2088-Arg). Using ACCase resistance mutations as molecular markers, combined with genetic, molecular and biochemical approaches, we found in individual resistant wild-oat plants that (1) up to three unlinked ACCase gene loci assort independently following Mendelian laws for disomic inheritance, (2) all three of these homoeologous ACCase genes were transcribed, with each able to carry its own mutation and (3) in a hexaploid background, each individual ACCase resistance mutation confers relatively low-level herbicide resistance, in contrast to high-level resistance conferred by the same mutations in unrelated diploid weed species of the Poaceae (grass) family. Low resistance conferred by individual ACCase resistance mutations is likely due to a dilution effect by susceptible ACCase expressed by homoeologs in hexaploid wild oat and/or differential expression of homoeologous ACCase gene copies. Thus, polyploidy in hexaploid wild oat may slow resistance evolution. Evidence of coexisting non-target-site resistance mechanisms among wild-oat populations was also revealed. In all, these results demonstrate that herbicide resistance and its evolution can be more complex in hexaploid wild oat than in unrelated diploid grass weeds. Our data provide a starting point for the daunting task of understanding resistance evolution in polyploids. PMID:23047200

Candidate gene analysis and identification of TRAP and SSR markers linked to the Or5 gene, which confers sunflower resistance to race E of broomrape (Orobanche cumana Wallr.)

Science.gov (United States)

Sunflower broomrape (Orobanche cumana Wallr.) is a root holoparasitic angiosperm considered as being one of the major constraints for sunflower production in Mediterranean areas. Breeding for resistance has been crucial for protecting sunflowers from broomrape damage. The Or5 gene, which confers re...

Reduced contact resistance of a-IGZO thin film transistors with inkjet-printed silver electrodes

Science.gov (United States)

Chen, Jianqiu; Ning, Honglong; Fang, Zhiqiang; Tao, Ruiqiang; Yang, Caigui; Zhou, Yicong; Yao, Rihui; Xu, Miao; Wang, Lei; Peng, Junbiao

2018-04-01

In this study, high performance amorphous In–Ga–Zn–O (a-IGZO) TFTs were successfully fabricated with inkjet-printed silver source-drain electrodes. The results showed that increased channel thickness has an improving trend in the properties of TFTs due to the decreased contact resistance. Compared with sputtered silver TFTs, devices with printed silver electrodes were more sensitive to the thickness of active layer. Furthermore, the devices with optimized active layer showed high performances with a maximum saturation mobility of 8.73 cm2 · V‑1 · S‑1 and an average saturation mobility of 6.97 cm2 · V‑1 · S‑1, I on/I off ratio more than 107 and subthreshold swing of 0.28 V/decade, which were comparable with the analogous devices with sputtered electrodes.

Crystallization and preliminary diffraction studies of SFC-1, a carbapenemase conferring antibiotic resistance

International Nuclear Information System (INIS)

Hong, Myoung-Ki; Lee, Jae Jin; Wu, Xing; Kim, Jin-Kwang; Jeong, Byeong Chul; Pham, Tan-Viet; Kim, Seung-Hwan; Lee, Sang Hee; Kang, Lin-Woo

2012-01-01

The SFC-1 gene from S. fonticola was cloned and SFC-1 was expressed, purified and crystallized. X-ray diffraction data were collected from an SFC-1 crystal to 1.6 Å resolution. SFC-1, a class A carbapenemase that confers antibiotic resistance, hydrolyzes the β-lactam rings of β-lactam antibiotics (carbapenems, cephalosporins, penicillins and aztreonam). SFC-1 presents an enormous challenge to infection control, particularly in the eradication of Gram-negative pathogens. As SFC-1 exhibits a remarkably broad substrate range, including β-lactams of all classes, the enzyme is a potential target for the development of antimicrobial agents against pathogens producing carbapenemases. In this study, SFC-1 was cloned, overexpressed, purified and crystallized. The SFC-1 crystal diffracted to 1.6 Å resolution and belonged to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 65.8, b = 68.3, c = 88.8 Å. Two molecules are present in the asymmetric unit, with a corresponding V M of 1.99 Å 3 Da −1 and a solvent content of 38.1%

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....

Crizotinib-Resistant Mutants of EML4-ALK Identified Through an Accelerated Mutagenesis Screen

Science.gov (United States)

Zhang, Sen; Wang, Frank; Keats, Jeffrey; Zhu, Xiaotian; Ning, Yaoyu; Wardwell, Scott D; Moran, Lauren; Mohemmad, Qurish K; Anjum, Rana; Wang, Yihan; Narasimhan, Narayana I; Dalgarno, David; Shakespeare, William C; Miret, Juan J; Clackson, Tim; Rivera, Victor M

2011-01-01

Activating gene rearrangements of anaplastic lymphoma kinase (ALK) have been identified as driver mutations in non-small-cell lung cancer, inflammatory myofibroblastic tumors, and other cancers. Crizotinib, a dual MET/ALK inhibitor, has demonstrated promising clinical activity in patients with non-small-cell lung cancer and inflammatory myofibroblastic tumors harboring ALK translocations. Inhibitors of driver kinases often elicit kinase domain mutations that confer resistance, and such mutations have been successfully predicted using in vitro mutagenesis screens. Here, this approach was used to discover an extensive set of ALK mutations that can confer resistance to crizotinib. Mutations at 16 residues were identified, structurally clustered into five regions around the kinase active site, which conferred varying degrees of resistance. The screen successfully predicted the L1196M, C1156Y, and F1174L mutations, recently identified in crizotinib-resistant patients. In separate studies, we demonstrated that crizotinib has relatively modest potency in ALK-positive non-small-cell lung cancer cell lines. A more potent ALK inhibitor, TAE684, maintained substantial activity against mutations that conferred resistance to crizotinib. Our study identifies multiple novel mutations in ALK that may confer clinical resistance to crizotinib, suggests that crizotinib's narrow selectivity window may underlie its susceptibility to such resistance and demonstrates that a more potent ALK inhibitor may be effective at overcoming resistance. PMID:22034911

The pepper Bs4C proteins are localized to the endoplasmic reticulum (ER) membrane and confer disease resistance to bacterial blight in transgenic rice.

Science.gov (United States)

Wang, Jun; Zeng, Xuan; Tian, Dongsheng; Yang, Xiaobei; Wang, Lanlan; Yin, Zhongchao

2018-03-30

Transcription activator-like effector (TALE)-dependent dominant disease resistance (R) genes in plants, also referred to as executor R genes, are induced on infection by phytopathogenic bacteria of the genus Xanthomonas harbouring the corresponding TALE genes. Unlike the traditional R proteins, the executor R proteins do not determine the resistance specificity and may function broadly in different plant species. The executor R gene Bs4C-R in the resistant genotype PI 235047 of the pepper species Capsicum pubescens (CpBs4C-R) confers disease resistance to Xanthomonas campestris pv. vesicatoria (Xcv) harbouring the TALE genes avrBsP/avrBs4. In this study, the synthetic genes of CpBs4C-R and two other Bs4C-like genes, the susceptible allele in the genotype PI585270 of C. pubescens (CpBs4C-S) and the CaBs4C-R homologue gene in the cultivar 'CM334' of Capsicum annum (CaBs4C), were characterized in tobacco (Nicotiana benthamiana) and rice (Oryza sativa). The Bs4C genes induced cell death in N. benthamiana. The functional Bs4C-eCFP fusion proteins were localized to the endoplasmic reticulum (ER) membrane in the leaf epidermal cells of N. benthamiana. The Xa10 promoter-Bs4C fusion genes in transgenic rice conferred strain-specific disease resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight in rice, and were specifically induced by the Xa10-incompatible Xoo strain PXO99 A (pHM1avrXa10). The results indicate that the Bs4C proteins from pepper species function broadly in rice and the Bs4C protein-mediated cell death from the ER is conserved between dicotyledonous and monocotyledonous plants, which can be utilized to engineer novel and enhanced disease resistance in heterologous plants. © 2018 TEMASEK LIFE SCIENCES LABORATORY. MOLECULAR PLANT PATHOLOGY © 2018 JOHN WILEY & SONS LTD.

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.

Dine Baa Hane Bi Naaltsoos: Collected Papers from the Seventh through Tenth Navajo Studies Conferences.

Science.gov (United States)

Piper, June-el, Ed.

This document contains 29 papers presented at the 7th-10th Navajo Studies Conferences, 1994-97. The papers are arranged in five sections: "Aesthetics: Rugs, Baskets, and Rock Art"; "Doing Anthropology"; "Health"; "Economics"; and "Contact between Cultures." The papers are: "The First Navajo Studies Conference: Reflections by the Cofounders"…

The Cytochrome P450 gene CYP6P12 confers pyrethroid resistance in kdr-free Malaysian populations of the dengue vector Aedes albopictus.

Science.gov (United States)

Ishak, Intan H; Riveron, Jacob M; Ibrahim, Sulaiman S; Stott, Rob; Longbottom, Joshua; Irving, Helen; Wondji, Charles S

2016-04-20

Control of Aedes albopictus, major dengue and chikungunya vector, is threatened by growing cases of insecticide resistance. The mechanisms driving this resistance remain poorly characterised. This study investigated the molecular basis of insecticide resistance in Malaysian populations of Ae. albopictus. Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance. CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations. Other detoxification genes also up-regulated in permethrin resistant mosquitoes included a glucuronosyltransferase (AAEL014279-RA) and the glutathione-S transferases GSTS1 and GSTT3. Functional analyses further supported that CYP6P12 contributes to pyrethroid resistance in Ae. albopictus as transgenic expression of CYP6P12 in Drosophila was sufficient to confer pyrethroid resistance in these flies. Furthermore, molecular docking simulations predicted CYP6P12 possessing enzymatic activity towards pyrethroids. Patterns of polymorphism suggested early sign of selection acting on CYP6P12 but not on CYP6N3. The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus.

On Ni/Au Alloyed Contacts to Mg-Doped GaN

Science.gov (United States)

Sarkar, Biplab; Reddy, Pramod; Klump, Andrew; Kaess, Felix; Rounds, Robert; Kirste, Ronny; Mita, Seiji; Kohn, Erhard; Collazo, Ramon; Sitar, Zlatko

2018-01-01

Ni/Au contacts to p-GaN were studied as a function of free hole concentration in GaN using planar transmission line measurement structures. All contacts showed a nonlinear behavior, which became stronger for lower doping concentrations. Electrical and structural analysis indicated that the current conduction between the contact and the p-GaN was through localized nano-sized clusters. Thus, the non-linear contact behavior can be well explained using the alloyed contact model. Two contributions to the contact resistance were identified: the spreading resistance in the semiconductor developed by the current crowding around the electrically active clusters, and diode-type behavior at the interface of the electrically active clusters with the semiconductor. Hence, the equivalent Ni/Au contact model consists of a diode and a resistor in series for each active cluster. The reduced barrier height observed in the measurements is thought to be generated by the extraction of Ga from the crystalline surface and localized formation of the Au:Ga phase. The alloyed contact analyses presented in this work are in good agreement with some of the commonly observed behavior of similar contacts described in the literature.

Highly reproducible and reliable metal/graphene contact by ultraviolet-ozone treatment

Energy Technology Data Exchange (ETDEWEB)

Li, Wei [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Hacker, Christina A.; Cheng, Guangjun; Hight Walker, A. R.; Richter, Curt A.; Gundlach, David J., E-mail: david.gundlach@nist.gov, E-mail: liangxl@pku.edu.cn [Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Liang, Yiran; Tian, Boyuan; Liang, Xuelei, E-mail: david.gundlach@nist.gov, E-mail: liangxl@pku.edu.cn; Peng, Lianmao [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China)

2014-03-21

Resist residue from the device fabrication process is a significant source of contamination at the metal/graphene contact interface. Ultraviolet Ozone (UVO) treatment is proven here, by X-ray photoelectron spectroscopy and Raman measurement, to be an effective way of cleaning the metal/graphene interface. Electrical measurements of devices that were fabricated by using UVO treatment of the metal/graphene contact region show that stable and reproducible low resistance metal/graphene contacts are obtained and the electrical properties of the graphene channel remain unaffected.

Highly reproducible and reliable metal/graphene contact by ultraviolet-ozone treatment

International Nuclear Information System (INIS)

Li, Wei; Hacker, Christina A.; Cheng, Guangjun; Hight Walker, A. R.; Richter, Curt A.; Gundlach, David J.; Liang, Yiran; Tian, Boyuan; Liang, Xuelei; Peng, Lianmao

2014-01-01

Resist residue from the device fabrication process is a significant source of contamination at the metal/graphene contact interface. Ultraviolet Ozone (UVO) treatment is proven here, by X-ray photoelectron spectroscopy and Raman measurement, to be an effective way of cleaning the metal/graphene interface. Electrical measurements of devices that were fabricated by using UVO treatment of the metal/graphene contact region show that stable and reproducible low resistance metal/graphene contacts are obtained and the electrical properties of the graphene channel remain unaffected

Insect Resistance to Bacillus thuringiensis Toxin Cry2Ab Is Conferred by Mutations in an ABC Transporter Subfamily A Protein.

Directory of Open Access Journals (Sweden)

Wee Tek Tay

2015-11-01

Full Text Available The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the

Ohmic contacts on n-type β-Ga2O3 using AZO/Ti/Au

Directory of Open Access Journals (Sweden)

Patrick H. Carey IV

2017-09-01

Full Text Available AZO interlayers between n-Ga2O3 and Ti/Au metallization significantly enhance Ohmic contact formation after annealing at ≥ 300°C. Without the presence of the AZO, similar anneals produce only rectifying current-voltage characteristics. Transmission Line Measurements of the Au/Ti/AZO/Ga2O3 stacks showed the specific contact resistance and transfer resistance decreased sharply from as-deposited values with annealing. The minimum contact resistance and specific contact resistance of 0.42 Ω-mm and 2.82 × 10-5 Ω-cm2 were achieved after a relatively low temperature 400°C annealing. The conduction band offset between AZO and Ga2O3 is 0.79 eV and provides a favorable pathway for improved electron transport across this interface.

Ohmic contacts on n-type β-Ga2O3 using AZO/Ti/Au

Science.gov (United States)

Carey, Patrick H.; Yang, Jiancheng; Ren, F.; Hays, David C.; Pearton, S. J.; Jang, Soohwan; Kuramata, Akito; Kravchenko, Ivan I.

2017-09-01

AZO interlayers between n-Ga2O3 and Ti/Au metallization significantly enhance Ohmic contact formation after annealing at ≥ 30 0°C. Without the presence of the AZO, similar anneals produce only rectifying current-voltage characteristics. Transmission Line Measurements of the Au/Ti/AZO/Ga2O3 stacks showed the specific contact resistance and transfer resistance decreased sharply from as-deposited values with annealing. The minimum contact resistance and specific contact resistance of 0.42 Ω-mm and 2.82 × 10-5 Ω-cm2 were achieved after a relatively low temperature 40 0°C annealing. The conduction band offset between AZO and Ga2O3 is 0.79 eV and provides a favorable pathway for improved electron transport across this interface.

GP88 (PC-Cell Derived Growth Factor, progranulin stimulates proliferation and confers letrozole resistance to aromatase overexpressing breast cancer cells

Directory of Open Access Journals (Sweden)

Sabnis Gauri

2011-06-01

Full Text Available Abstract Background Aromatase inhibitors (AI that inhibit breast cancer cell growth by blocking estrogen synthesis have become the treatment of choice for post-menopausal women with estrogen receptor positive (ER+ breast cancer. However, some patients display de novo or acquired resistance to AI. Interactions between estrogen and growth factor signaling pathways have been identified in estrogen-responsive cells as one possible reason for acquisition of resistance. Our laboratory has characterized an autocrine growth factor overexpressed in invasive ductal carcinoma named PC-Cell Derived Growth Factor (GP88, also known as progranulin. In the present study, we investigated the role GP88 on the acquisition of resistance to letrozole in ER+ breast cancer cells Methods We used two aromatase overexpressing human breast cancer cell lines MCF-7-CA cells and AC1 cells and their letrozole resistant counterparts as study models. Effect of stimulating or inhibiting GP88 expression on proliferation, anchorage-independent growth, survival and letrozole responsiveness was examined. Results GP88 induced cell proliferation and conferred letrozole resistance in a time- and dose-dependent fashion. Conversely, naturally letrozole resistant breast cancer cells displayed a 10-fold increase in GP88 expression when compared to letrozole sensitive cells. GP88 overexpression, or exogenous addition blocked the inhibitory effect of letrozole on proliferation, and stimulated survival and soft agar colony formation. In letrozole resistant cells, silencing GP88 by siRNA inhibited cell proliferation and restored their sensitivity to letrozole. Conclusion Our findings provide information on the role of an alternate growth and survival factor on the acquisition of aromatase inhibitor resistance in ER+ breast cancer.

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

Adriamycin resistance, heat resistance and radiation response in Chinese hamster fibroblasts

International Nuclear Information System (INIS)

Wallner, K.; Li, G.

1985-01-01

Previous investigators have demonstrated synergistic interaction between hyperthermia and radiation or Adriamycin (ADR), using cell lines that are sensitive to heat or ADR alone. The authors investigated the effect of heat, radiation or ADR on Chinese hamster fibroblasts (HA-1), their heat resistant variants and their ADR resistant variants. Heat for ADR resistance did not confer cross resistance to radiation. Cells resistant to heat did show cross resistance to ADR. While cells selected for ADR resistance were not cross resistant to heat, they did not exhibit drug potentiation by hyperthermia, characteristic of ADR sensitive cells. Cytofluorometric measurement showed decreased ADR uptake in both heat and ADR resistant cells. The possibility of cross resistance between heat and ADR should be considered when designing combined modality trials

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

Source/drain electrodes contact effect on the stability of bottom-contact pentacene field-effect transistors

Directory of Open Access Journals (Sweden)

Xinge Yu

2012-06-01

Full Text Available Bottom-contact pentacene field-effect transistors were fabricated with a PMMA dielectric layer, and the air stability of the transistors was investigated. To characterize the device stability, the field-effect transistors were exposed to ambient conditions for 30 days and subsequently characterized. The degradation of electrical performance was traced to study the variation of field-effect mobility, saturation current and off-state current. By investigating the morphology variance of the pentacene film at the channel and source/drain (S/D contact regions by atomic force microscopy, it was clear that the morphology of the pentacene film adhered to the S/D degenerated dramatically. Moreover, by studying the variation of contact resistance in detail, it was found that the S/D contact effect was the main reason for the degradation in performance.

Antifolate resistance mediated by the multidrug resistance proteins MRP1 and MRP2

NARCIS (Netherlands)

Hooijberg, J. H.; Broxterman, H. J.; Kool, M.; Assaraf, Y. G.; Peters, G. J.; Noordhuis, P.; Scheper, R. J.; Borst, P.; Pinedo, H. M.; Jansen, G.

1999-01-01

Transfection of multidrug resistance proteins (MRPs) MRP1 and MRP2 in human ovarian carcinoma 2008 cells conferred a marked level of resistance to short-term (1-4 h) exposure to the polyglutamatable antifolates methotrexate (MTX; 21-74-fold), ZD1694 (4-138-fold), and GW1843 (101-156-fold). Evidence

Palladium silicide - a new contact for semiconductor radiation detectors

International Nuclear Information System (INIS)

Totterdell, D.H.J.

1981-11-01

Silicide layers can be used as low resistance contacts in semiconductor devices. The formation of a metal rich palladium silicide Pd 2 Si is discussed. A palladium film 100A thick is deposited at 300 0 C and the resulting silicide layer used as an ohmic contact in an n + p silicon detector. This rugged contact has electrical characteristics comparable with existing evaporated gold contacts and enables the use of more reproducible bonding techniques. (author)

Characterization of Deposited Platinum Contacts onto Discrete Graphene Flakes for Electrical Devices

KAUST Repository

Holguin Lerma, Jorge A.

2016-05-03

For years, electron beam induced deposition has been used to fabricate electrical contacts for micro and nanostructures. The role of the contact resistance is key to achieve high performance and efficiency in electrical devices. The present thesis reports on the electrical, structural and chemical characterization of electron beam deposited platinum electrodes that are exposed to different steps of thermal annealing and how they are used in four-probe devices of ultrathin graphite (uG) flakes (<100nm thickness). The device integration of liquid phase exfoliated uG is demonstrated, and its performance compared to devices made with analogous mechanically exfoliated uG. For both devices, similar contact resistances of ~2kΩ were obtained. The electrical measurements confirm a 99.5% reduction in contact resistance after vacuum thermal annealing at 300 °C. Parallel to this, Raman characterization confirms the formation of a nanocrystalline carbon structure over the electrode. While this could suggest an enhancement of the electrical transport in the device, an additional thermal annealing step in air at 300 °C, promoted the oxidation and removal of the carbon shell and confirmed that the contact resistance remained the same. Overall this shows that the carbon shell along the electrode has no significant role in the contact resistance. Finally, the challenges based on topographical analysis of the deposited electrodes are discussed. Reduction of the electrode’s height down to one-third of the initial value, increased surface roughness, formation of voids along the electrodes and the onset of platinum nanoparticles near the area of deposition, represent a challenge for future work.

Lr67/Yr46 confers adult plant resistance to stem rust and powdery mildew in wheat.

Science.gov (United States)

Herrera-Foessel, Sybil A; Singh, Ravi P; Lillemo, Morten; Huerta-Espino, Julio; Bhavani, Sridhar; Singh, Sukhwinder; Lan, Caixia; Calvo-Salazar, Violeta; Lagudah, Evans S

2014-04-01

We demonstrate that Lr67/Yr46 has pleiotropic effect on stem rust and powdery mildew resistance and is associated with leaf tip necrosis. Genes are designated as Sr55, Pm46 and Ltn3 , respectively. Wheat (Triticum aestivum) accession RL6077, known to carry the pleiotropic slow rusting leaf and yellow rust resistance genes Lr67/Yr46 in Thatcher background, displayed significantly lower stem rust (P. graminis tritici; Pgt) and powdery mildew (Blumeria graminis tritici; Bgt) severities in Kenya and in Norway, respectively, compared to its recurrent parent Thatcher. We investigated the resistance of RL6077 to stem rust and powdery mildew using Avocet × RL6077 F6 recombinant inbred lines (RILs) derived from two photoperiod-insensitive F3 families segregating for Lr67/Yr46. Greenhouse seedling tests were conducted with Mexican Pgt race RTR. Field evaluations were conducted under artificially initiated stem rust epidemics with Pgt races RTR and TTKST (Ug99 + Sr24) at Ciudad Obregon (Mexico) and Njoro (Kenya) during 2010-2011; and under natural powdery mildew epiphytotic in Norway at Ås and Hamar during 2011 and 2012. In Mexico, a mean reduction of 41 % on stem rust severity was obtained for RILs carrying Lr67/Yr46, compared to RILs that lacked the gene, whereas in Kenya the difference was smaller (16 %) but significant. In Norway, leaf tip necrosis was associated with Lr67/Yr46 and RILs carrying Lr67/Yr46 showed a 20 % reduction in mean powdery mildew severity at both sites across the 2 years of evaluation. Our study demonstrates that Lr67/Yr46 confers partial resistance to stem rust and powdery mildew and is associated with leaf tip necrosis. The corresponding pleiotropic, or tightly linked, genes, designated as Sr55, Pm46, and Ltn3, can be utilized to provide broad-spectrum durable disease resistance in wheat.

Targeted sequencing identifies genetic alterations that confer primary resistance to EGFR tyrosine kinase inhibitor (Korean Lung Cancer Consortium).

Science.gov (United States)

Lim, Sun Min; Kim, Hye Ryun; Cho, Eun Kyung; Min, Young Joo; Ahn, Jin Seok; Ahn, Myung-Ju; Park, Keunchil; Cho, Byoung Chul; Lee, Ji-Hyun; Jeong, Hye Cheol; Kim, Eun Kyung; Kim, Joo-Hang

2016-06-14

Non-small-cell lung cancer (NSCLC) patients with activating epidermal growth factor receptor (EGFR) mutations may exhibit primary resistance to EGFR tyrosine kinase inhibitor (TKI). We aimed to examine genomic alterations associated with de novo resistance to gefitinib in a prospective study of NSCLC patients. One-hundred and fifty two patients with activating EGFR mutations were included in this study and 136 patients' tumor sample were available for targeted sequencing of genomic alterations in 22 genes using the Colon and Lung Cancer panel (Ampliseq, Life Technologies). All 132 patients with EGFR mutation were treated with gefitinib for their treatment of advanced NSCLC. Twenty patients showed primary resistance to EGFR TKI, and were classified as non-responders. A total of 543 somatic single-nucleotide variants (498 missense, 13 nonsense) and 32 frameshift insertions/deletions, with a median of 3 mutations per sample. TP53 was most commonly mutated (47%) and mutations in SMAD4 was also common (19%), as well as DDR2 (16%), PIK3CA (15%), STK11 (14%), and BRAF (7%). Genomic mutations in the PI3K/Akt/mTOR pathway were commonly found in non-responders (45%) compared to responders (27%), and they had significantly shorter progression-free survival and overall survival compared to patients without mutations (2.1 vs. 12.8 months, P=0.04, 15.7 vs. not reached, PAkt/mTOR pathway were commonly identified in non-responders and may confer resistance to EGFR TKI. Screening lung adenocarcinoma patients with clinical cancer gene test may aid in selecting out those who show primary resistance to EGFR TKI (NCT01697163).

A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

International Nuclear Information System (INIS)

Basu, A; Adams, G G; McGruer, N E

2016-01-01

Direct contact, ohmic MEMS switches for RF applications have several advantages over other conventional switching devices. Advantages include lower insertion loss, higher isolation, and better switching figure-of-merit (cut-off frequency). The most important aspect of a direct-contact RF MEMS switch is the metal microcontact which can dictate the lifetime and reliability of the switch. Therefore, an understanding of contact reliability is essential for developing robust MEMS switches. This paper discusses and reviews the most important work done over the past couple of decades toward understanding ohmic micro-contacts. We initially discuss the contact mechanics and multi-physics models for studying Hertzian and multi-asperity contacts. We follow this with a discussion on models and experiments for studying adhesion. We then discuss experimental setups and the development of contact test stations by various groups for accelerated testing of microcontacts, as well as for analysis of contact reliability issues. Subsequently, we analyze a number of material transfer mechanisms in microcontacts under hot and cold switching conditions. We finally review the material properties that can help determine the selection of contact materials. A trade-off between contact resistance and high reliability is almost always necessary during selection of contact material; this paper discusses how the choice of materials can help address such trade-offs. (paper)

Antibiotic resistance patterns and beta-lactamase identification in ...

African Journals Online (AJOL)

Background. Antibiotic resistance is a growing problem worldwide. Mechanisms of resistance vary, and some can confer resistance to multiple classes of antibiotics. Objective. To characterise the antibiotic resistance profiles of Escherichia coli isolates obtained from stool samples of young rural children exposed or ...

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...

Understanding channel and contact effects on transport in 1-dimensional nanotransistors.

Energy Technology Data Exchange (ETDEWEB)

Swartzentruber, Brian S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Delker, Collin James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Yoo, Jinkyoung [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Janes, David B. [Purdue Univ., West Lafayette, IN (United States)

2015-02-01

Nanowire transistors are generally formed by metal contacts to a uniformly doped nanowire. The transistor can be modeled as a series combination of resistances from both the channel and the contacts. In this study, a simple model is proposed consisting of a resistive channel in series with two Schottky metal-semiconductor contacts modeled using the WKB approximation. This model captures several phenomena commonly observed in nanowire transistor measurements, including the mobility as a function of gate potential, mobility reduction with respect to bulk mobility, and non-linearities in output characteristics. For example, the maximum measured mobility as a function of gate voltage in a nanowire transistor can be predicted based on the semiconductor bulk mobility in addition to barrier height and other properties of the contact. The model is then extended to nanowires with axial p-n junctions having an inde- pendent gate over each wire segment by splitting the channel resistance into a series component for each doping segment. Finally, the contact-channel model is applied to low-frequency noise analysis in nanowire devices, where the noise can be generated in both the channel and the contacts. Because contacts play a major, yet often neglected, role in nanowire transistor operation, they must be accounted for in order to extract meaningful parameters from I-V and noise measurements.

Pediatric fecal microbiota harbor diverse and novel antibiotic resistance genes.

Directory of Open Access Journals (Sweden)

Aimée M Moore

Full Text Available Emerging antibiotic resistance threatens human health. Gut microbes are an epidemiologically important reservoir of resistance genes (resistome, yet prior studies indicate that the true diversity of gut-associated resistomes has been underestimated. To deeply characterize the pediatric gut-associated resistome, we created metagenomic recombinant libraries in an Escherichia coli host using fecal DNA from 22 healthy infants and children (most without recent antibiotic exposure, and performed functional selections for resistance to 18 antibiotics from eight drug classes. Resistance-conferring DNA fragments were sequenced (Illumina HiSeq 2000, and reads assembled and annotated with the PARFuMS computational pipeline. Resistance to 14 of the 18 antibiotics was found in stools of infants and children. Recovered genes included chloramphenicol acetyltransferases, drug-resistant dihydrofolate reductases, rRNA methyltransferases, transcriptional regulators, multidrug efflux pumps, and every major class of beta-lactamase, aminoglycoside-modifying enzyme, and tetracycline resistance protein. Many resistance-conferring sequences were mobilizable; some had low identity to any known organism, emphasizing cryptic organisms as potentially important resistance reservoirs. We functionally confirmed three novel resistance genes, including a 16S rRNA methylase conferring aminoglycoside resistance, and two tetracycline-resistance proteins nearly identical to a bifidobacterial MFS transporter (B. longum s. longum JDM301. We provide the first report to our knowledge of resistance to folate-synthesis inhibitors conferred by a predicted Nudix hydrolase (part of the folate synthesis pathway. This functional metagenomic survey of gut-associated resistomes, the largest of its kind to date, demonstrates that fecal resistomes of healthy children are far more diverse than previously suspected, that clinically relevant resistance genes are present even without recent selective

Investigations of metal contacts to amorphous evaporated Ge films and amorphous sputtered Si films

International Nuclear Information System (INIS)

Hafiz, M.; Mgbenu, E.; Tove, P.A.; Norde, H.; Petersson, S.

1976-02-01

Amorphous Ge or Si films have been used as ohmic contacts to high-resistivity n-silicon radiation detectors. One interesting property of this contact is that it does not inject minority carriers even when the depletion region extends up to the contact thus generating an extracting field there. The function of this contact is not yet fully explored. One part problem is the role of the metal films used as external contacts to the amorphous film. In this report the function of different contacting metals, such as Au, Al, Cr are investigated by measuring the I-V-characteristics of sandwich structures with two metals on both sides of the amorphous evaporated (Ge) and sputtered (Si) film (of typical thickness 1000 A). It was found that while the symmetric structures Au-αGe-Au and Cr-αGe-Cr were low-resistive (leading to resistivity values of approximately 10 5 Ωcm for the αGe film), Al-αGe-Al structures showed much higher resistance and were also polarity dependent. The former feature was found also for unsymmetric structures, i.e. Cr-αGe-Au, Cr-αGe-Al. (Auth.)

An improved method for transformation of lettuce by Agrobacterium tumefaciens with a gene that confers freezing resistance

Directory of Open Access Journals (Sweden)

Pileggi Marcos

2001-01-01

Full Text Available An efficient method for constructing transgenic lettuce cultivars by Agrobacterium tumefaciens was described by Torres et al., 1993. In the present work, an improvement of the above procedure is described and applied to transform the cultivar Grand Rapids with a mutated P5CS gene. The major modifications were concerned with turning more practical the transformation and regeneration protocols. Also we tried to improve transformation steps by increasing injured area in explants and prolonging co-cultivation with Agrobacteria (in larger concentration. A more significant selective pressure was used against non-transformed plants and bacteria. In these work we were concerned to obtain T1 and T2 seeds. The P5CS gene codes for a delta¹-pyrroline-5-carboxylate synthetase, a bifunctional enzyme that catalyzes two steps of proline biosynthesis in plants (Zhang et al., 1995; Peng et al., 1996, while the mutated gene is insensitive to feedback inhibition by proline. The potential benefit of this gene is to confer water stress resistance (drought, salt, cold due to increased intracellular levels of proline that works like an osmoprotectant. In this work could obtain and characterize transgenic lettuce lineages which are resistant to freezing temperature.

Overexpression of Rice Auxilin-Like Protein, XB21, Induces Necrotic Lesions, up-Regulates Endocytosis-Related Genes, and Confers Enhanced Resistance to Xanthomonas oryzae pv. oryzae.

Science.gov (United States)

Park, Chang-Jin; Wei, Tong; Sharma, Rita; Ronald, Pamela C

2017-12-01

The rice immune receptor XA21 confers resistance to the bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo). To elucidate the mechanism of XA21-mediated immunity, we previously performed a yeast two-hybrid screening for XA21 interactors and identified XA21 binding protein 21 (XB21). Here, we report that XB21 is an auxilin-like protein predicted to function in clathrin-mediated endocytosis. We demonstrate an XA21/XB21 in vivo interaction using co-immunoprecipitation in rice. Overexpression of XB21 in rice variety Kitaake and a Kitaake transgenic line expressing XA21 confers a necrotic lesion phenotype and enhances resistance to Xoo. RNA sequencing reveals that XB21 overexpression results in the differential expression of 8735 genes (4939 genes up- and 3846 genes down-regulated) (≥2-folds, FDR ≤0.01). The up-regulated genes include those predicted to be involved in 'cell death' and 'vesicle-mediated transport'. These results indicate that XB21 plays a role in the plant immune response and in regulation of cell death. The up-regulation of genes controlling 'vesicle-mediated transport' in XB21 overexpression lines is consistent with a functional role for XB21 as an auxilin.

An AFLP marker linked to the Pm-1 gene that confers resistance to Podosphaera xanthii race 1 in Cucumis melo