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Sample records for channel conductance measurements

  1. Measurements of void fraction by an improved multi-channel conductance void meter

    International Nuclear Information System (INIS)

    Song, Chul-Hwa; Chung, Moon Ki; No, Hee Cheon

    1998-01-01

    An improved multi-channel Conductance Void Meter (CVM) was developed to measure a void fraction. Its measuring principle is basically based upon the differences of electrical conductance of a two-phase mixture due to the variation of void fraction around a sensor. The sensor is designed to be flush-mounted to the inner wall of the test section to avoid the flow disturbances. The signal processor with three channels is specially designed so as to minimize the inherent error due to the phase difference between channels. It is emphasized that the guard electrodes are electrically shielded in order not to affect the measurements of two-phase mixture conductance, but to make the electric fields evenly distributed in a measuring volume. Void fraction is measured for bubbly and slug flow regimes in a vertical air-water loop, and statistical signal processing techniques are applied to show that CVM has a good dynamic resolution which is required to investigate the structural developments of bubbly flow and the propagation of void waves in a flow channel. (author)

  2. CONDUCTIVE CHANNEL FOR ENERGY TRANSMISSION

    Directory of Open Access Journals (Sweden)

    V. V. Apollonov

    2014-01-01

    Full Text Available Laser spark obtained by using a conical optics is much more appropriate to form conducting channels in atmosphere. Only two types of lasers are actively considered to be used in forming high-conductivity channels in atmosphere, controlled by laser spark: pulsed sub-microsecond gas and chemical lasers (CO2, DF and short pulse solid-state and UV lasers. Main advantage of short pulse lasers is their ability in forming of super long ionized channels with a characteristic diameter of ~100  µ  in atmosphere along the  beam propagation direction. At estimated electron densities below  10 ⋅ 16 cm–3 in these filaments and laser wavelengths in the range of 0,5–1,0 mm, the plasma barely absorbs laser radiation.  In this case, the length of the track composed of many filaments is determined by the laser intensity and may reach many kilometers at a femtosecond pulse energy of ~100 mJ. However, these lasers could not be used to form high-conductivity long channels in atmosphere. The ohmic resistance of this type a conducting channels turned out to be very high, and the gas in the channels could not be strongly heated (< 1 J. An electric breakdown controlled by radiation of femtosecond solid-state laser was implemented in only at a length of 3 m with a voltage of 2 MV across the discharge gap (670 kV/m.Not so long ago scientific group from P. N. Lebedev has improved that result, the discharge gap – 1 m had been broken under KrF laser irradiation when switching high-voltage (up to 390 kV/m electric discharge by 100-ns UV pulses. Our previous result  –  16 m long conducting channel controlled by a  laser spark at the voltage  –  3 MV  – was obtained more than 20 years ago in Russia and Japan by using pulsed CO2  laser with energy  –  0,5 kJ. An average electric field strength  was < 190 kV/m. It is still too much for efficient applications.

  3. Droplet interface bilayer reconstitution and activity measurement of the mechanosensitive channel of large conductance from Escherichia coli.

    Science.gov (United States)

    Barriga, Hanna M G; Booth, Paula; Haylock, Stuart; Bazin, Richard; Templer, Richard H; Ces, Oscar

    2014-09-06

    Droplet interface bilayers (DIBs) provide an exciting new platform for the study of membrane proteins in stable bilayers of controlled composition. To date, the successful reconstitution and activity measurement of membrane proteins in DIBs has relied on the use of the synthetic lipid 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC). We report the functional reconstitution of the mechanosensitive channel of large conductance (MscL) into DIBs composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), a lipid of significantly greater biological relevance than DPhPC. MscL functionality has been demonstrated using a fluorescence-based assay, showing that dye flow occurs across the DIB when MscL is gated by the cysteine reactive chemical 2-(trimethylammonium)ethyl methane thiosulfonate bromide (MTSET). MscL has already been the subject of a number of studies investigating its interaction with the membrane. We propose that this method will pave the way for future MscL studies looking in detail at the effects of controlled composition or membrane asymmetry on MscL activity using biologically relevant lipids and will also be applicable to other lipid-protein systems, paving the way for the study of membrane proteins in DIBs with biologically relevant lipids.

  4. Conductance of Ion Channels - Theory vs. Experiment

    Science.gov (United States)

    Pohorille, Andrew; Wilson, Michael; Mijajlovic, Milan

    2013-01-01

    . In addition, once the free energy profile becomes available the full current-voltage dependence can be readily obtained. For both channels we carried out calculations using both approaches. We also tested the main assumptions underlying the diffusive model, such as uncorrelated nature of individual crossing events and Fickian diffusion. The accuracy and consistency of different methods will be discussed. Finally we will discuss how comparisons between calculated and measured ionic conductance and selectivity of transport can be used for determining structural models of the channels.

  5. Pore size matters for potassium channel conductance

    Science.gov (United States)

    Moldenhauer, Hans; Pincuntureo, Matías

    2016-01-01

    Ion channels are membrane proteins that mediate efficient ion transport across the hydrophobic core of cell membranes, an unlikely process in their absence. K+ channels discriminate K+ over cations with similar radii with extraordinary selectivity and display a wide diversity of ion transport rates, covering differences of two orders of magnitude in unitary conductance. The pore domains of large- and small-conductance K+ channels share a general architectural design comprising a conserved narrow selectivity filter, which forms intimate interactions with permeant ions, flanked by two wider vestibules toward the internal and external openings. In large-conductance K+ channels, the inner vestibule is wide, whereas in small-conductance channels it is narrow. Here we raise the idea that the physical dimensions of the hydrophobic internal vestibule limit ion transport in K+ channels, accounting for their diversity in unitary conductance. PMID:27619418

  6. Measurement of thermal conductance

    International Nuclear Information System (INIS)

    Kuchnir, M.

    1977-01-01

    The 6-m long, 45-kG, warm-iron superconducting magnets envisioned for the Energy Doubler stage of the Fermilab accelerator require stiff supports with minimized thermal conductances in order to keep the refrigeration power reasonable. The large number of supports involved in the system required a careful study of their heat conduction from the room temperature wall to the intercepting refrigeration at 20 0 K and to the liquid helium. For this purpose the thermal conductance of this support was measured by comparing it with the thermal conductance of a copper strap of known geometry. An association of steady-state thermal analysis and experimental thermal conductivity techniques forms the basis of this method. An important advantage is the automatic simulation of the 20 0 K refrigeration intercept by the copper strap, which simplifies the apparatus considerably. This relative resistance technique, which uses electrical analogy as a guideline, is applicable with no restrictions for materials with temperature-independent thermal conductivity. For other materials the results obtained are functions of the specific temperature interval involved in the measurements. A comprehensive review of the literature on thermal conductivity indicates that this approach has not been used before. A demonstration of its self-consistency is stressed here rather than results obtained for different supports

  7. MHD-flow in slotted channels with conducting walls

    International Nuclear Information System (INIS)

    Evtushenko, I.A.; Kirillov, I.R.; Reed, C.B.

    1994-07-01

    A review of experimental results is presented for magnetohydrodynamic (MHD) flow in rectangular channels with conducting walls and high aspect ratios (longer side parallel to the applied magnetic field), which are called slotted channels. The slotted channel concept was conceived at Efremov Institute as a method for reducing MHD pressure drop in liquid metal cooled blanket design. The experiments conducted by the authors were aimed at studying both fully developed MHD-flow, and the effect of a magnetic field on the hydrodynamics of 3-D flows in slotted channels. Tests were carried out on five models of the slotted geometry. A good agreement between test and theoretical results for the pressure drop in slotted channels was demonstrated. Application of a open-quotes one-electrode movable probeclose quotes for velocity measurement permitted measurement of the M-shape velocity profiles in the slotted channels. Suppression of 3-D inertial effects in slotted channels of complex geometry was demonstrated based on potential distribution data

  8. Channel box dimension measuring method

    International Nuclear Information System (INIS)

    Oshima, Hirotake; Jo, Hiroto.

    1994-01-01

    The present invention provides a method for measuring the entire length of a channel box of a fuel assembly of a BWR type reactor. Namely, four sensors are used as one set that generate ultrasonic waves from oblique upper portion, oblique lower portion, upper portion and lower portion of the channel box respectively. The distances between the four sensors and each of the portions of the channel box are measured respectively for both of a reference member and a member to be measured. The entire length of the channel box is measured by calculating the measured values and the angles of the obliquely disposed sensors according to a predetermined formula. According to the method of the present invention, the inclination of the channel box to be measured can be corrected. In addition, accuracy of the measurement is improved and the measuring time is saved as well as the measuring device and operation can be simplified. (I.S.)

  9. Structure of conducting channel of lightning

    International Nuclear Information System (INIS)

    Alanakyan, Yu. R.

    2013-01-01

    The spatial distribution of the plasma density in a lightning channel is studied theoretically. It is shown that the electric-field double layer is formed at the channel boundary. In this case, the electron temperature changes abruptly and ions are accelerated by the electric field of the double layer. The ion momentum flux density is close to the surrounding gas pressure. Cleaning of the channel from heavy particles occurs in particle-exchange processes between the plasma channel and the surrounding air. Hydrogen ions are accumulated inside the expanding channel from the surrounding air, which is enriched by hydrogen-contained molecules. In this case, the plasma channel is unstable and splits to a chain of equidistant bunches of plasma. The hydrogen-enrich bunches burn diffusely after recombination exhibiting the bead lightning behavior

  10. On conduction in a bacterial sodium channel.

    Directory of Open Access Journals (Sweden)

    Simone Furini

    Full Text Available Voltage-gated Na⁺-channels are transmembrane proteins that are responsible for the fast depolarizing phase of the action potential in nerve and muscular cells. Selective permeability of Na⁺ over Ca²⁺ or K⁺ ions is essential for the biological function of Na⁺-channels. After the emergence of the first high-resolution structure of a Na⁺-channel, an anionic coordination site was proposed to confer Na⁺ selectivity through partial dehydration of Na⁺ via its direct interaction with conserved glutamate side chains. By combining molecular dynamics simulations and free-energy calculations, a low-energy permeation pathway for Na⁺ ion translocation through the selectivity filter of the recently determined crystal structure of a prokaryotic sodium channel from Arcobacter butzleri is characterised. The picture that emerges is that of a pore preferentially occupied by two ions, which can switch between different configurations by crossing low free-energy barriers. In contrast to K⁺-channels, the movements of the ions appear to be weakly coupled in Na⁺-channels. When the free-energy maps for Na⁺ and K⁺ ions are compared, a selective site is characterised in the narrowest region of the filter, where a hydrated Na⁺ ion, and not a hydrated K⁺ ion, is energetically stable.

  11. Molecular Dynamics Simulation of the Antiamoebin Ion Channel: Linking Structure and Conductance

    Science.gov (United States)

    Wilson, Michael A.; Wei, Chenyu; Bjelkmar, Paer; Wallace, B. A.; Pohorille, Andrew

    2011-01-01

    Molecular dynamics simulations were carried out in order to ascertain which of the potential multimeric forms of the transmembrane peptaibol channel, antiamoebin, is consistant with its measured conductance. Estimates of the conductance obtained through counting ions that cross the channel and by solving the Nernst-Planck equation yield consistent results, indicating that the motion of ions inside the channel can be satisfactorily described as diffusive.The calculated conductance of octameric channels is markedly higher than the conductance measured in single channel recordings, whereas the tetramer appears to be non-conducting. The conductance of the hexamer was estimated to be 115+/-34 pS and 74+/-20 pS, at 150 mV and 75 mV, respectively, in satisfactory agreement with the value of 90 pS measured at 75 mV. On this basis we propose that the antiamoebin channel consists of six monomers. Its pore is large enough to accommodate K(+) and Cl(-) with their first solvation shells intact. The free energy barrier encountered by K(+) is only 2.2 kcal/mol whereas Cl(-) encounters a substantially higher barrier of nearly 5 kcal/mol. This difference makes the channel selective for cations. Ion crossing events are shown to be uncorrelated and follow Poisson statistics. keywords: ion channels, peptaibols, channel conductance, molecular dynamics

  12. Radio propagation measurement and channel modelling

    CERN Document Server

    Salous, Sana

    2013-01-01

    While there are numerous books describing modern wireless communication systems that contain overviews of radio propagation and radio channel modelling, there are none that contain detailed information on the design, implementation and calibration of radio channel measurement equipment, the planning of experiments and the in depth analysis of measured data. The book would begin with an explanation of the fundamentals of radio wave propagation and progress through a series of topics, including the measurement of radio channel characteristics, radio channel sounders, measurement strategies

  13. Conductivity mapping of underground flow channels and moisture anomalies in carbonate terrain using electromagnetic methods

    International Nuclear Information System (INIS)

    Pin, F.G.; Ketelle, R.H.

    1983-11-01

    Electromagnetic methods have been used to measure apparent terrain conductivity in the downstream portion of a watershed in which a waste disposal site is proposed. At that site, the pathways for waste migration in groundwater are controlled by subsurface channels. The identification and mapping of these subsurfaces channels constitutes an important contribution to the site characterization study. The channels are identified using isocurves of measured apparent conductivity. Two upstream channel branches are found to merge into a single downstream channel which constitutes the main drainage path out of the watershed. Electromagnetic terrain conductivity measurement methods are found to be inexpensive, rapid and efficient tools for subsurface investigations. Their contribution to site characterization studies and pathways analyses is particularly significant in planning of the monitoring program, the hydrogeological testing, and the modeling study. The results reported so far are very promising for use of the methods in several other applications related to the subgrade disposal of waste. 7 references, 5 figures

  14. Cationic Polymers Inhibit the Conductance of Lysenin Channels

    Directory of Open Access Journals (Sweden)

    Daniel Fologea

    2013-01-01

    Full Text Available The pore-forming toxin lysenin self-assembles large and stable conductance channels in natural and artificial lipid membranes. The lysenin channels exhibit unique regulation capabilities, which open unexplored possibilities to control the transport of ions and molecules through artificial and natural lipid membranes. Our investigations demonstrate that the positively charged polymers polyethyleneimine and chitosan inhibit the conducting properties of lysenin channels inserted into planar lipid membranes. The preservation of the inhibitory effect following addition of charged polymers on either side of the supporting membrane suggests the presence of multiple binding sites within the channel's structure and a multistep inhibition mechanism that involves binding and trapping. Complete blockage of the binding sites with divalent cations prevents further inhibition in conductance induced by the addition of cationic polymers and supports the hypothesis that the binding sites are identical for both multivalent metal cations and charged polymers. The investigation at the single-channel level has shown distinct complete blockages of each of the inserted channels. These findings reveal key structural characteristics which may provide insight into lysenin’s functionality while opening innovative approaches for the development of applications such as transient cell permeabilization and advanced drug delivery systems.

  15. Microstructural information from channeling measurements

    International Nuclear Information System (INIS)

    Quere, Y.

    1984-09-01

    Channeling is sensitive to nearly all structural changes in solids. One briefly recalls how particles are dechanneled by lattice defects and describes the main applications of channeling to materials science: detection of radiation damage, location of impurity atoms, precipitations in alloys... Channeling being a phenomenon characteristic of perfect crystals, any type of lattice imperfection (phonons, crystal defects, precipitation etc.) is expected to produce dechanneling. Consequently channeling and its opposite, dechanneling, have both been used to study structure and structural changes of materials

  16. Multi-channel grouping techniques for conducting reactor safety studies

    International Nuclear Information System (INIS)

    Waltar, A.E.; Wilburn, N.P.

    1975-01-01

    In conducting safety studies for postulated unprotected accidents in an LMFBR system, it is common practice to employ multi-channel coupled neutronics, thermal hydraulics computer programs such as SAS3A or MELT-III. The multichannel feature of such code systems is important if the natural fuel failure incoherencies and the resulting sodium void/fuel motion reactivity feedbacks--which have strong spatial variations--are to be properly modeled. Because of the large amounts of computer time associated with many channel runs, however, there is a strong incentive to conduct parametric studies with as few channels as possible. The paper presented is focused on methods successfully employed to accomplish this end for a study of the hypothetical unprotected transient overpower accident conducted for the FFTF

  17. Endothelial Small- and Intermediate-Conductance KCa Channels

    DEFF Research Database (Denmark)

    Wulff, Heike; Köhler, Ralf

    2013-01-01

    ABSTRACT:: Most cardiovascular researchers are familiar with intermediate-conductance KCa3.1 and small-conductance KCa2.3 channels because of their contribution to endothelium-derived hyperpolarization (EDH). However, to immunologists and neuroscientists these channels are primarily known...... for their role in lymphocyte activation and neuronal excitability. KCa3.1 is involved in the proliferation and migration of T cells, B cell, mast cells, macrophages, fibroblasts and dedifferentiated vascular smooth muscle cells and is, therefore, being pursued as a potential target for use in asthma...

  18. A sodium-channel mutation causes isolated cardiac conduction disease

    NARCIS (Netherlands)

    Tan, HL; Bink-Boelkens, MTE; Bezzina, CR; Viswanathan, PC; Beaufort-Krol, GCM; van Tintelen, PJ; van den Berg, MP; Wilde, AAM; Balser, [No Value

    2001-01-01

    Cardiac conduction disorders slow the heart rhythm and cause disability in millions of people worldwide. Inherited mutations in SCN5A, the gene encoding the human cardiac sodium (Na+) channel, have been associated with rapid heart rhythms that occur suddenly and are life-threatening(1-3); however, a

  19. A sodium-channel mutation causes isolated cardiac conduction disease

    NARCIS (Netherlands)

    Tan, H. L.; Bink-Boelkens, M. T.; Bezzina, C. R.; Viswanathan, P. C.; Beaufort-Krol, G. C.; van Tintelen, P. J.; van den Berg, M. P.; Wilde, A. A.; Balser, J. R.

    2001-01-01

    Cardiac conduction disorders slow the heart rhythm and cause disability in millions of people worldwide. Inherited mutations in SCN5A, the gene encoding the human cardiac sodium (Na+) channel, have been associated with rapid heart rhythms that occur suddenly and are life-threatening; however, a

  20. Stretchable transistors with buckled carbon nanotube films as conducting channels

    Science.gov (United States)

    Arnold, Michael S; Xu, Feng

    2015-03-24

    Thin-film transistors comprising buckled films comprising carbon nanotubes as the conductive channel are provided. Also provided are methods of fabricating the transistors. The transistors, which are highly stretchable and bendable, exhibit stable performance even when operated under high tensile strains.

  1. Dimension measuring method for channel box

    International Nuclear Information System (INIS)

    Jo, Hiroto.

    1995-01-01

    The device of the present invention concerns detection of a channel box for spent fuel assemblies of a BWR type reactor, which measures a cross sectional shape and dimension of the channel box to check deformation amount such as expansion. That is, a customary fuel exchanger and a dimension measuring device are used. The lower end of the channel box is measured by a distance sensor of the dimension measuring device when it is aligned with a position of the distance sensor. The channel box is lowered at the same time while detecting axial position data of the fuel exchanger. The position of the channel box in an axial direction is detected based on axial position data of the fuel exchanger. The lower end of the channel box can accurately be recognized by the detection of both of them. Subsequent deformation measurement for the channel box at accurate axial positions is enabled. In addition, since the axial position data of the fuel exchanger per se are detected, an axial profile of the channel box can be measured even if a lifting speed of the channel box is varied on every region. (I.S.)

  2. Indoor MIMO Channel Measurement and Modeling

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Andersen, Jørgen Bach

    2005-01-01

    Forming accurate models of the multiple input multiple output (MIMO) channel is essential both for simulation as well as understanding of the basic properties of the channel. This paper investigates different known models using measurements obtained with a 16x32 MIMO channel sounder for the 5.8GHz...... band. The measurements were carried out in various indoor scenarios including both temporal and spatial aspects of channel changes. The models considered include the so-called Kronecker model, a model proposed by Weichselberger et. al., and a model involving the full covariance matrix, the most...

  3. Channel Measurements and Characteristics for Cooperative Positioning Applications

    DEFF Research Database (Denmark)

    Wang, Wei; Steinböck, Gerhard; Jost, Thomas

    2012-01-01

    We have conducted an indoor channel measurement campaign to characterize the propagation channel for the development of cooperative positioning algorithms. The campaign focused particularly on the characteristics of multi-link channels with applications to positioning. In this contribution we...... present the measurement campaign and preliminary results on correlation characteristics of the received power. It is observed that the link-pair log power is uncorrelated. Moreover, the received log power can be modeled by realizations of independent Gaussian distributions for each link, based...... on the measured results....

  4. Measuring vibrations in fuel channels CNE

    International Nuclear Information System (INIS)

    Martín Ghiselli, A.; Fiori, J.; Sacchi, M.; Villabrille, G.

    2013-01-01

    This paper present a description of implementation and execution of vibration measurements made at the request of NUCLEOELECTRICA ARGENTINA S.A. on the ends of the reactor fuel channels of Embalse Nuclear Power Plant to explore possible differences between the dynamic behavior of empty fuel channel and with full charge of fuel elements inside. (author)

  5. A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes

    Science.gov (United States)

    Shanafield, Margaret; Niswonger, Richard G.; Prudic, David E.; Pohll, Greg; Susfalk, Richard; Panday, Sorab

    2014-01-01

    Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow-front velocities in initially dry channels. The diffusion-wave approximation to the Saint-Venant equations, coupled with Philip's equation for infiltration, is connected to the groundwater model MODFLOW and is calibrated by adjusting the saturated hydraulic conductivity of the channel bed. The model is applied to portions of two large water delivery canals, which serve as proxies for natural ephemeral streams. Estimated seepage rates compare well with previously published values. Possible sources of error stem from uncertainty in Manning's roughness coefficients, soil hydraulic properties and channel geometry. Model performance would be most improved through more frequent longitudinal estimates of channel geometry and thalweg elevation, and with measurements of stream stage over time to constrain wave timing and shape. This model is a potentially valuable tool for estimating spatial variability in longitudinal seepage along intermittent and ephemeral channels over a wide range of bed slopes and the influence of seepage rates on groundwater levels.

  6. Frequency Dependence of Measured Massive MIMO Channel Properties

    DEFF Research Database (Denmark)

    Oliveras Martínez, Àlex; Carvalho, Elisabeth De; Nielsen, Jesper Ødum

    2016-01-01

    A multi-user massive MIMO measurement campaign is conducted to study the channel propagation characteristics (e.g. user correlation, sum of eigenvalues and condition number), focusing on the stability over frequencies and the impact of the array aperture. We use 3 arrays with 64 antennas (6m linear...... array, 2m linear array and 25cm by 28cm squared 2D array) serving 8 users holding a handset with 2 antennas. The study of the measurements shows that the propagation characteristics of the channel are stable for all the measured frequencies. We also observe that user proximity and user handgrip...... stabilize the studied properties of the channel across the frequencies, and in such case the larger the aperture of the array the more stable the properties. The number of base station antennas improves the propagation characteristics of the channel and stabilizes the properties in the frequency domain....

  7. Pore dimensions and the role of occupancy in unitary conductance of Shaker K channels

    Science.gov (United States)

    Díaz-Franulic, Ignacio; Sepúlveda, Romina V.; Navarro-Quezada, Nieves; González-Nilo, Fernando

    2015-01-01

    K channels mediate the selective passage of K+ across the plasma membrane by means of intimate interactions with ions at the pore selectivity filter located near the external face. Despite high conservation of the selectivity filter, the K+ transport properties of different K channels vary widely, with the unitary conductance spanning a range of over two orders of magnitude. Mutation of Pro475, a residue located at the cytoplasmic entrance of the pore of the small-intermediate conductance K channel Shaker (Pro475Asp (P475D) or Pro475Gln (P475Q)), increases Shaker’s reported ∼20-pS conductance by approximately six- and approximately threefold, respectively, without any detectable effect on its selectivity. These findings suggest that the structural determinants underlying the diversity of K channel conductance are distinct from the selectivity filter, making P475D and P475Q excellent probes to identify key determinants of the K channel unitary conductance. By measuring diffusion-limited unitary outward currents after unilateral addition of 2 M sucrose to the internal solution to increase its viscosity, we estimated a pore internal radius of capture of ∼0.82 Å for all three Shaker variants (wild type, P475D, and P475Q). This estimate is consistent with the internal entrance of the Kv1.2/2.1 structure if the effective radius of hydrated K+ is set to ∼4 Å. Unilateral exposure to sucrose allowed us to estimate the internal and external access resistances together with that of the inner pore. We determined that Shaker resistance resides mainly in the inner cavity, whereas only ∼8% resides in the selectivity filter. To reduce the inner resistance, we introduced additional aspartate residues into the internal vestibule to favor ion occupancy. No aspartate addition raised the maximum unitary conductance, measured at saturating [K+], beyond that of P475D, suggesting an ∼200-pS conductance ceiling for Shaker. This value is approximately one third of the maximum

  8. Calibration-free electrical conductivity measurements for highly conductive slags

    International Nuclear Information System (INIS)

    Macdonald, Christopher J.; Gao, Huang; Pal, Uday B.; Van den Avyle, James A.; Melgaard, David K.

    2000-01-01

    This research involves the measurement of the electrical conductivity (K) for the ESR (electroslag remelting) slag (60 wt.% CaF 2 - 20 wt.% CaO - 20 wt.% Al 2 O 3 ) used in the decontamination of radioactive stainless steel. The electrical conductivity is measured with an improved high-accuracy-height-differential technique that requires no calibration. This method consists of making continuous AC impedance measurements over several successive depth increments of the coaxial cylindrical electrodes in the ESR slag. The electrical conductivity is then calculated from the slope of the plot of inverse impedance versus the depth of the electrodes in the slag. The improvements on the existing technique include an increased electrochemical cell geometry and the capability of measuring high precision depth increments and the associated impedances. These improvements allow this technique to be used for measuring the electrical conductivity of highly conductive slags such as the ESR slag. The volatilization rate and the volatile species of the ESR slag measured through thermogravimetric (TG) and mass spectroscopy analysis, respectively, reveal that the ESR slag composition essentially remains the same throughout the electrical conductivity experiments

  9. HANARO core channel flow-rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Il; Chae, Hee Tae; Im, Don Soon; Kim, Seon Duk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    HANARO core consists of 23 hexagonal flow tubes and 16 cylindrical flow tubes. To get the core flow distribution, we used 6 flow-rate measuring dummy fuel assemblies (instrumented dummy fuel assemblies). The differential pressures were measured and converted to flow-rates using the predetermined relationship between AP and flow-rate for each instrumented dummy fuel assemblies. The flow-rate for the cylindrical flow channels shows +-7% relative errors and that for the hexagonal flow channels shows +-3.5% relative errors. Generally the flow-rates of outer core channels show smaller values compared to those of inner core. The channels near to the core inlet pipe and outlet pipes also show somewhat lower flow-rates. For the lower flow channels, the thermal margin was checked by considering complete linear power histories. From the experimental results, the gap flow-rate was estimated to be 49.4 kg/s (cf. design flow of 50 kg/s). 15 tabs., 9 figs., 10 refs. (Author) .new.

  10. Large-conductance Ca2+-activated K+ channel β1-subunit knockout mice are not hypertensive

    Science.gov (United States)

    Garver, Hannah; Galligan, James J.; Fink, Gregory D.

    2011-01-01

    Large-conductance Ca2+-activated K+ (BK) channels are composed of pore-forming α-subunits and accessory β1-subunits that modulate Ca2+ sensitivity. BK channels regulate arterial myogenic tone and renal Na+ clearance/K+ reabsorption. Previous studies using indirect or short-term blood pressure measurements found that BK channel β1-subunit knockout (BK β1-KO) mice were hypertensive. We evaluated 24-h mean arterial pressure (MAP) and heart rate in BK β1-KO mice using radiotelemetry. BK β1-KO mice did not have a higher 24-h average MAP when compared with wild-type (WT) mice, although MAP was ∼10 mmHg higher at night. The dose-dependent peak declines in MAP by nifedipine were only slightly larger in BK β1-KO mice. In BK β1-KO mice, giving 1% NaCl to mice to drink for 7 days caused a transient (5 days) elevation of MAP (∼5 mmHg); MAP returned to pre-saline levels by day 6. BK β1-KO mesenteric arteries in vitro demonstrated diminished contractile responses to paxilline, increased reactivity to Bay K 8644 and norepinephrine (NE), and maintained relaxation to isoproterenol. Paxilline and Bay K 8644 did not constrict WT or BK β1-KO mesenteric veins (MV). BK β1-subunits are not expressed in MV. The results indicate that BK β1-KO mice are not hypertensive on normal or high-salt intake. BK channel deficiency increases arterial reactivity to NE and L-type Ca2+ channel function in vitro, but the L-type Ca2+ channel modulation of MAP is not altered in BK β1-KO mice. BK and L-type Ca2+ channels do not modulate murine venous tone. It appears that selective loss of BK channel function in arteries only is not sufficient to cause sustained hypertension. PMID:21131476

  11. Acrolein-mediated conduction loss is partially restored by K+ channel blockers

    Science.gov (United States)

    Yan, Rui; Page, Jessica C.

    2015-01-01

    Acrolein-mediated myelin damage is thought to be a critical mechanism leading to conduction failure following neurotrauma and neurodegenerative diseases. The exposure and activation of juxtaparanodal voltage-gated K+ channels due to myelin damage leads to conduction block, and K+ channel blockers have long been studied as a means for restoring axonal conduction in spinal cord injury (SCI) and multiple sclerosis (MS). In this study, we have found that 100 μM K+ channel blockers 4-aminopyridine-3-methanol (4-AP-3-MeOH), and to a lesser degree 4-aminopyridine (4-AP), can significantly restore compound action potential (CAP) conduction in spinal cord tissue following acrolein-mediated myelin damage using a well-established ex vivo SCI model. In addition, 4-AP-3-MeOH can effectively restore CAP conduction in acrolein-damaged axons with a range of concentrations from 0.1 to 100 μM. We have also shown that while both compounds at 100 μM showed no preference of small- and large-caliber axons when restoring CAP conduction, 4-AP-3-MeOH, unlike 4-AP, is able to augment CAP amplitude while causing little change in axonal responsiveness measured in refractory periods and response to repetitive stimuli. In a prior study, we show that 4-AP-3-MeOH was able to functionally rescue mechanically injured axons. In this investigation, we conclude that 4-AP-3-MeOH is an effective K+ channel blocker in restoring axonal conduction following both primary (physical) and secondary (chemical) insults. These findings also suggest that 4-AP-3-MeOH is a viable alternative of 4-AP for treating myelin damage and improving function following central nervous system trauma and neurodegenerative diseases. PMID:26581866

  12. Detection of irradiated potatoes by conductivity measurements

    International Nuclear Information System (INIS)

    Scherz, H.

    1991-01-01

    In this paper, the author shows that the conductivity of irradiated potatoes measured by a sticking electrode depend on the irradiation dose and is independent on the potato variety. The measured values remain constant over a six month storage period

  13. Top quark mass measurement in dilepton channel

    International Nuclear Information System (INIS)

    Lysak, R.

    2007-01-01

    In this work, we measured the top quark mass in tt'-' events produced in pp'-' interactions at the center-of-mass energy 1.96 TeV using CDF detector. We used dilepton in tt'-' events where both W bosons from top quarks are decaying into leptons. The data sample corresponds to 340 pb -1 . We found there 33 tt'-' candidates while expecting 10.5 ± 1.9 background events. In the measurement, we reconstruct one, representative mass for each event using the assumption about longitudinal momentum of in tt'-' system, in order to be able to kinematically solve the under-constrained system. The mass distributions (templates) are created for simulated signal and background events. Templates are parametrized in order to obtain smooth probability density functions. Likelihood maximization which includes these parametrized templates is then performed on reconstructed masses obtained from data sample in order to obtain final top quark mass estimate. The result of applying this procedure on data events is top quark mass estimate 169.5 +7. 7 - 7.2 (stat.) ± 4.0(syst.) GeV/c 2 for 30 out of 33 candidates, where the solution for top quark mass was found. This measurement was a part of first top quark mass measurement in dilepton channel at CDF in Run II. The top quark mass measured here is consistent with the CDF measurement in dilepton channel from Run I M top = 167.4 ± 10.3(stat.) ± 4.8(syst.) GeV/c 2 . Moreover, the combined result of four top quark mass measurements in dilepton channel from Run II (one of these four measurements is our measurement) M top = 167.9 ± 5.2(stat.) ± 3.7(syst.) GeV/c 2 significantly (by ∼ 40%) improved the precision of top quark mass determination from Run I. It should be also noted, that this combined result is consistent with measurement obtained in 'lepton+jets' channel at CDF in Run II (M top = 173.5 +3.9 -3.8 GeV/c 2 ). So, we don't have yet any indication about new physics beyond the Standard Model. My main contribution in this analysis was

  14. Quantification and distribution of big conductance Ca2+-activated K+ channels in kidney epithelia

    DEFF Research Database (Denmark)

    Grunnet, Morten; Hay-Schmidt, Anders; Klaerke, Dan A

    2005-01-01

    and immunohistochemical studies. In cortical collecting ducts, BK channels were exclusively located in principal cells while no channels could be found in intercalated cells. The abundant and distinct distribution in kidney epithelia talks in favor for BK channels being important contributors in maintaining salt......Big conductance Ca2+ activated K+ channels (BK channels) is an abundant channel present in almost all kind of tissue. The accurate quantity and especially the precise distribution of this channel in kidney epithelia are, however, still debated. The aim of the present study has therefore been...... to examine the presence of BK channels in kidney epithelia and determine the actual number and distribution of these channels. For this purpose, a selective peptidyl ligand for BK channels called iberiotoxin or the radiolabeled double mutant analog 125I-IbTX-D19Y/Y36F has been employed. The presence of BK...

  15. Localization of Ca2+ -activated big-conductance K+ channels in rabbit distal colon

    DEFF Research Database (Denmark)

    Hay-Schmidt, Anders; Grunnet, Morten; Abrahamse, Salomon L

    2003-01-01

    Big-conductance Ca(2+)-activated K(+) channels (BK channels) may play an important role in the regulation of epithelial salt and water transport, but little is known about the expression level and the precise localization of BK channels in epithelia. The aim of the present study was to quantify a...

  16. Immunolocalization and expression of small-conductance calcium-activated potassium channels in human myometrium

    DEFF Research Database (Denmark)

    Rosenbaum, Sofia T; Svalø, Julie; Nielsen, Karsten

    2012-01-01

    Small-conductance calcium-activated potassium (SK3) channels have been detected in human myometrium and we have previously shown a functional role of SK channels in human myometrium in vitro. The aims of this study were to identify the precise localization of SK3 channels and to quantify SK3 m....... This is the first report to provide evidence for a possible role of SK3 channels in human uterine telocytes....

  17. Ion Transport in Confined Geometries below the Nanoscale: Access Resistance Dominates Protein Channel Conductance in Diluted Solutions.

    Science.gov (United States)

    Alcaraz, Antonio; López, M Lidón; Queralt-Martín, María; Aguilella, Vicente M

    2017-10-24

    Synthetic nanopores and mesoscopic protein channels have common traits like the importance of electrostatic interactions between the permeating ions and the nanochannel. Ion transport at the nanoscale occurs under confinement conditions so that the usual assumptions made in microfluidics are challenged, among others, by interfacial effects such as access resistance (AR). Here, we show that a sound interpretation of electrophysiological measurements in terms of channel ion selective properties requires the consideration of interfacial effects, up to the point that they dominate protein channel conductance in diluted solutions. We measure AR in a large ion channel, the bacterial porin OmpF, by means of single-channel conductance measurements in electrolyte solutions containing varying concentrations of high molecular weight PEG, sterically excluded from the pore. Comparison of experiments performed in charged and neutral planar membranes shows that lipid surface charges modify the ion distribution and determine the value of AR, indicating that lipid molecules are more than passive scaffolds even in the case of large transmembrane proteins. We also found that AR may reach up to 80% of the total channel conductance in diluted solutions, where electrophysiological recordings register essentially the AR of the system and depend marginally on the pore characteristics. These findings may have implications for several low aspect ratio biological channels that perform their physiological function in a low ionic strength and macromolecule crowded environment, just the two conditions enhancing the AR contribution.

  18. A measuring generator for testing spectrometric channels

    International Nuclear Information System (INIS)

    Dinh Sy Hien; Kalinkin, A.I.

    1984-01-01

    A measuring generator for testing and tuning an amplitude spectrometric channel is described. The device consists of a pseudo random pulse generator, constructed on shifters, a sawtooth wave generator and a shaper of stable amplitude pulses with exponential decay times. The device is made as CAMAC unit width modules and has the following specifications: average pulse repetition rate of pseudo random pulses is 3.1; 25; 50; 100; 200 kHz; peak amplitude of 2 Hz pulse repetition of saw tooth pulses is 6 V; peak amplitude of exponential shape pulses is 5 V. The block-diagram and basic circuits of the device are given

  19. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications

    Directory of Open Access Journals (Sweden)

    Francisco J. Cañete

    2016-02-01

    Full Text Available Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression.

  20. Measurement of temperature, electric conductivity and density of plasma

    International Nuclear Information System (INIS)

    Vasilevova, I.; Nefedov, A.; Oberman, F.; Urinson, A.

    1982-01-01

    Three instruments are briefly described developed by the High Temperatures Institute of the USSR Academy of Sciences for the measurement of plasma temperature, electric conductivity and density. The temperature measuring instrument uses as a standard a light source whose temperature may significantly differ from plasma temperature because three light fluxes are compared, namely the flux emitted by the plasma, the flux emitted directly by the standard source, and the flux emitted by the standard source after passage through the plasma. The results of measurement are computer processed. Electric conductivity is measured using a coil placed in a probe which is automatically extended for a time of maximally 0.3 seconds into the plasma stream. The equipment for measuring plasma density consists of a special single-channel monochromator, a temperature gauge, a plasma pressure gauge, and of a computer for processing the results of measurement. (Ha)

  1. DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications

    International Nuclear Information System (INIS)

    Katoh, Y.; Kondo, S.; Snead, L.L.

    2009-01-01

    High purity chemically vapor-deposited silicon carbide (SiC) and 2D continuous SiC fiber, chemically vapor-infiltrated SiC matrix composites with pyrocarbon interphases were examined. Specifically, temperature dependent (RT to 800 deg. C) electrical conductivity and the influence of neutron irradiation were measured. The influence of neutron irradiation on electrical properties appeared very strong for the SiC of this study, typically resulting in orders lower ambient conductivity and steeper temperature dependency of this conductivity. For the 2D composites, through-thickness (normal to the fiber axis') electrical conductivity was dominated by bypass conduction via interphase network at relatively low temperatures, whereas conduction through SiC constituents dominated at higher temperatures. Through-thickness electrical conductivity of neutron-irradiated 2D SiC composites with thin PyC interphase, currently envisioned for flow channel insert application, will likely in the order of 10 S/m at the appropriate operating temperature. Mechanisms of electrical conduction in the composites and irradiation-induced modification of electrical conductivity of the composites and their constituents are discussed.

  2. Performance Evaluation of Proportional Fair Scheduling Algorithm with Measured Channels

    DEFF Research Database (Denmark)

    Sørensen, Troels Bundgaard; Pons, Manuel Rubio

    2005-01-01

    subjected to measured channel traces. Specifically, we applied measured signal fading recorded from GSM cell phone users making calls on an indoor wireless office system. Different from reference channel models, these measured channels have much more irregular fading between users, which as we show...

  3. Thermal conductivity measurements of pacific illite sediment

    Science.gov (United States)

    Hickox, C. E.; McVey, D. F.; Miller, J. B.; Olson, L. O.; Silva, A. J.

    1986-07-01

    Results are reported for effective thermal conductivity measurements performed in situ and in core samples of illite marine sediment. The measurements were obtained during a recent oceanographic expedition to a study site in the north central region of the Pacific Ocean. This study was undertaken in support of the U.S. Subseabed Disposal Project, the purpose of which is to investigate the scientific feasibility of using the fine-grained sediments of the sea floor as a repository for high-level nuclear waste. In situ measurements were made and 1.5-m-long hydrostatic piston cores were taken, under remote control, from a platform that was lowered to the sea floor, 5844 m below sea level. The in situ measurement of thermal conductivity was made at a nominal depth of 80 cm below the sediment surface using a specially developed, line-source, needle probe. Thermal conductivity measurements in three piston cores and one box core (obtained several kilometers from the study site) were made on shipboard using a miniature needle probe. The in situ thermal conductivity was approximately 0.91 W · m-1 · K-1. Values determined from the cores were within the range 0.81 to 0.89 W · m-1 · K-1.

  4. Thermal conductivity measurements of Pacific illite sediment

    International Nuclear Information System (INIS)

    Hickox, C.E.; McVey, D.F.; Miller, J.B.; Olson, L.O.; Silva, A.J.

    1986-01-01

    Results are reported for effective thermal conductivity measurements performed in situ and in core samples of illite marine sediment. The measurements were obtained during a recent oceanographic expedition to a study site in the north central region of the Pacific Ocean. This study was undertaken in support of the US Subseabed Disposal Project, the purpose of which is to investigate the scientific feasibility of using the fine grained sediments of the sea floor as a repository for high level nuclear waste. In situ measurements were made and 1.5-meter long hydrostatic piston cores were taken, under remote control, from a platform that was lowered to the sea floor, 5844 m below sea level. The in situ measurement of thermal conductivity was made at a nominal depth of 80 cm below the sediment surface using a specially developed, line source, needle probe. Thermal conductivity measurements in three piston cores and one box core (obtained several kilometers from the study site) were made on shipboard using a miniature needle probe. The in situ thermal conductivity was approximately 0.91 W/m.K. Values determined from the cores were within the range 0.81 to 0.89 W/m.K

  5. Dual-goniometer system for channeling measurements

    International Nuclear Information System (INIS)

    Linden, M.; Hellborg, R.

    1986-03-01

    This paper describes a two-goniometer system for obtaining azimuthally averaged measurements in channeling experiments. The system consists of a tri-axial master goniometer and a bi-axial goniometer. Both goniometers are controlled by stepping motors. The alignment goniometer has a target holder, which permits the beam spot to be placed anywhere in a 6 x 6 mm 2 square on the target crystal without loosing the target orientation. The design, construction and operation of the goniometers as well as stepping motor control units and programs for computer control of the goniometers are described. Two control programs cover orientation of the target crystal and a number of other normal experimental conditions. (author)

  6. Scanning nanoscale multiprobes for conductivity measurements

    DEFF Research Database (Denmark)

    Bøggild, Peter; Hansen, Torben Mikael; Kuhn, Oliver

    2000-01-01

    We report fabrication and measurements with two- and four-point probes with nanoscale dimensions, for high spatial resolution conductivity measurements on surfaces and thin films. By combination of conventional microfabrication and additive three-dimensional nanolithography, we have obtained...... electrode spacings down to 200 nm. At the tips of four silicon oxide microcantilevers, narrow carbon tips are grown in converging directions and subsequently coated with a conducting layer. The probe is placed in contact with a conducting surface, whereby the electrode resistance can be determined....... The nanoelectrodes withstand considerable contact force before breaking. The probe offers a unique possibility to position the voltage sensors, as well as the source and drain electrodes in areas of nanoscale dimensions. ©2000 American Institute of Physics....

  7. Measurement of conductive hearing loss in mice.

    Science.gov (United States)

    Qin, Zhaobing; Wood, Melissa; Rosowski, John J

    2010-05-01

    In order to discriminate conductive hearing loss from sensorineural impairment, quantitative measurements were used to evaluate the effect of artificial conductive pathology on distortion-product otoacoustic emissions (DPOAEs), auditory brainstem responses (ABRs) and laser-Doppler vibrometry (LDV) in mice. The conductive manipulations were created by perforating the pars flaccida of the tympanic membrane, filling or partially filling the middle-ear cavity with saline, fixing the ossicular chain, and interrupting the incudo-stapedial joint. In the saline-filled and ossicular-fixation groups, averaged DPOAE thresholds increased relative to the control state by 20-36 and 25-39 dB, respectively with the largest threshold shifts occurring at frequencies less than 20kHz, while averaged ABR thresholds increased 12-19 and 12-25 dB, respectively without the predominant low-frequency effect. Both DPOAE and ABR thresholds were elevated by less than 10 dB in the half-filled saline condition; no significant change was observed after pars flaccida perforation. Conductive pathology generally produced a change in DPOAE threshold in dB that was 1.5-2.5 times larger than the ABR threshold change at frequencies less than 30 kHz; the changes in the two thresholds were nearly equal at the highest frequencies. While mild conductive pathology (ABR threshold shifts of conductive hearing losses (ABR threshold shifts >10 dB) were associated with significant deceases in DPOAE growth rate. Our LDV measurements are consistent with others and suggest that measurements of umbo velocity are not an accurate indicator of conductive hearing loss produced by ossicular lesions in mice. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  8. Large-conductance calcium-dependent potassium channels prevent dendritic excitability in neocortical pyramidal neurons.

    Science.gov (United States)

    Benhassine, Narimane; Berger, Thomas

    2009-03-01

    Large-conductance calcium-dependent potassium channels (BK channels) are homogeneously distributed along the somatodendritic axis of layer 5 pyramidal neurons of the rat somatosensory cortex. The relevance of this conductance for dendritic calcium electrogenesis was studied in acute brain slices using somatodendritic patch clamp recordings and calcium imaging. BK channel activation reduces the occurrence of dendritic calcium spikes. This is reflected in an increased critical frequency of somatic spikes necessary to activate the distal initiation zone. Whilst BK channels repolarise the somatic spike, they dampen it only in the distal dendrite. Their activation reduces dendritic calcium influx via glutamate receptors. Furthermore, they prevent dendritic calcium electrogenesis and subsequent somatic burst discharges. However, the time window for coincident somatic action potential and dendritic input to elicit dendritic calcium events is not influenced by BK channels. Thus, BK channel activation in layer 5 pyramidal neurons affects cellular excitability primarily by establishing a high threshold at the distal action potential initiation zone.

  9. Conduction channels of an InAs-Al nanowire Josephson weak link

    International Nuclear Information System (INIS)

    Goffman, M F; Urbina, C; Pothier, H; Nygård, J; Marcus, C M; Krogstrup, P

    2017-01-01

    We present a quantitative characterization of an electrically tunable Josephson junction defined in an InAs nanowire proximitized by an epitaxially-grown superconducting Al shell. The gate-dependence of the number of conduction channels and of the set of transmission coefficients are extracted from the highly nonlinear current–voltage characteristics. Although the transmissions evolve non-monotonically, the number of independent channels can be tuned, and configurations with a single quasi-ballistic channel achieved. (fast track communication)

  10. A Fast and Robust Method for Measuring Optical Channel Gain

    DEFF Research Database (Denmark)

    Harbo, Anders La-Cour; Stoustrup, Jakob; Villemoes, L.F.

    2000-01-01

    We present a numerically stable and computational simple method for fast and robust measurement of optical channel gain. By transmitting adaptively designed signals through the channel, good accuracy is possible even in severe noise conditions......We present a numerically stable and computational simple method for fast and robust measurement of optical channel gain. By transmitting adaptively designed signals through the channel, good accuracy is possible even in severe noise conditions...

  11. Measuring Balance Across Multiple Radar Receiver Channels.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.; Bickel, Douglas L.

    2018-03-01

    When radar receivers employ multiple channels, the general intent is for the receive channels to be as alike as possible, if not as ideal as possible. This is usually done via prudent hardware design, supplemented by system calibration. Towards this end, we require a quality metric for ascertaining the goodness of a radar channel, and the degree of match to sibling channels. We propose a relevant and useable metric to do just that. Acknowledgements This report was the result of an unfunded research and development activity.

  12. 5-HT1A receptors modulate small-conductance Ca2+-activated K+ channels

    DEFF Research Database (Denmark)

    Grunnet, Morten; Jespersen, Thomas; Perrier, Jean-François

    2004-01-01

    Small-conductance calcium-activated potassium channels (SK) are responsible for the medium afterhyperpolarisation (mAHP) following action potentials in neurons. Here we tested the ability of serotonin (5-HT) to modulate the activity of SK channels by coexpressing 5-HT1A receptors with different...

  13. Inhibition of small-conductance Ca2+-activated K+ channels terminates and protects against atrial fibrillation

    DEFF Research Database (Denmark)

    Diness, Jonas Goldin; Sørensen, Ulrik S; Nissen, Jakob Dahl

    2010-01-01

    Recently, evidence has emerged that small-conductance Ca(2+)-activated K(+) (SK) channels are predominantly expressed in the atria in a number of species including human. In rat, guinea pig, and rabbit ex vivo and in vivo models of atrial fibrillation (AF), we used 3 different SK channel inhibito...

  14. Impact of a bone conduction communication channel on multichannel communication system effectiveness.

    Science.gov (United States)

    Blue, Misty; McBride, Maranda; Weatherless, Rachel; Letowski, Tomasz

    2013-04-01

    In this study, the impact of including a bone conduction transducer in a three-channel spatialized communication system was investigated. Several military and security forces situations require concurrent listening to three or more radio channels. In such radio systems, spatial separation between three concurrent radio channels can be achieved by delivering separate signals to the left and right earphone independently and both earphones simultaneously. This method appears to be effective; however, the use of bone conduction as one channel may provide both operational and performance benefits. Three three-channel communication systems were used to collect speech intelligibility data from 18 listeners (System I, three loudspeakers; System 2, stereo headphones; System 3, stereo headphones and a bone conduction vibrator). Each channel presented signals perceived to originate from separate locations. Volunteers listened to three sets of competing sentences and identified a number, color, and object spoken in the target sentence. Each listener participated in three trials (one per system). Each trial consisted of 48 competing sentence sets. Systems 2 and 3 were more intelligible than System I. Systems 2 and 3 were overall equally intelligible; however, the intelligibility of all three channels was significantly more balanced in System 3. Replacing an air conduction transducer with a bone conduction transducer in a multichannel audio device can provide a more effective and balanced simultaneous monitoring auditory environment. These results have important design and implementation implications for spatial auditory communication equipment.

  15. Large conductance Ca2+-activated K+ (BK channel: Activation by Ca2+ and voltage

    Directory of Open Access Journals (Sweden)

    RAMÓN LATORRE

    2006-01-01

    Full Text Available Large conductance Ca2+-activated K+ (BK channels belong to the S4 superfamily of K+ channels that include voltage-dependent K+ (Kv channels characterized by having six (S1-S6 transmembrane domains and a positively charged S4 domain. As Kv channels, BK channels contain a S4 domain, but they have an extra (S0 transmembrane domain that leads to an external NH2-terminus. The BK channel is activated by internal Ca2+, and using chimeric channels and mutagenesis, three distinct Ca2+-dependent regulatory mechanisms with different divalent cation selectivity have been identified in its large COOH-terminus. Two of these putative Ca2+-binding domains activate the BK channel when cytoplasmic Ca2+ reaches micromolar concentrations, and a low Ca2+ affinity mechanism may be involved in the physiological regulation by Mg2+. The presence in the BK channel of multiple Ca2+-binding sites explains the huge Ca2+ concentration range (0.1 μM-100 μM in which the divalent cation influences channel gating. BK channels are also voltage-dependent, and all the experimental evidence points toward the S4 domain as the domain in charge of sensing the voltage. Calcium can open BK channels when all the voltage sensors are in their resting configuration, and voltage is able to activate channels in the complete absence of Ca2+. Therefore, Ca2+ and voltage act independently to enhance channel opening, and this behavior can be explained using a two-tiered allosteric gating mechanism.

  16. Divalent Metal Ion Transport across Large Biological Ion Channels and Their Effect on Conductance and Selectivity

    Directory of Open Access Journals (Sweden)

    Elena García-Giménez

    2012-01-01

    Full Text Available Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH. We extend here the characterization of the OmpF porin, a wide channel of the outer membrane of E. coli, by studying the effect of salts of divalent cations on the transport properties of the channel. The regulation of divalent cations concentration is essential in cell metabolism and understanding their effects is of key importance, not only in the channels specifically designed to control their passage but also in other multiionic channels. In particular, in porin channels like OmpF, divalent cations modulate the efficiency of molecules having antimicrobial activity. Taking advantage of the fact that the OmpF channel atomic structure has been resolved both in water and in MgCl2 aqueous solutions, we analyze the single channel conductance and the channel selectivity inversion aiming to separate the role of the electrolyte itself, and the counterion accumulation induced by the protein channel charges and other factors (binding, steric effects, etc. that being of minor importance in salts of monovalent cations become crucial in the case of divalent cations.

  17. Intraocular pressure measurements after conductive keratoplasty.

    Science.gov (United States)

    Kymionis, George D; Naoumidi, Tatiana L; Aslanides, Ioannis M; Kumar, Vinod; Astyrakakis, Nikolaos I; Tsilimbaris, Miltiadis; Pallikaris, Ioannis G

    2005-01-01

    To determine the possible impact of conductive keratoplasty (CK) on intraocular pressure (IOP) measurements. A prospective, single-center, noncomparative interventional case series was performed. Baseline and postoperative IOPs were measured by Goldmann applanation tonometry in 32 eyes of 18 patients who underwent CK for hyperopia correction. Mean follow-up was 11.9 months (range: 8 to 18 months). After CK, a statistically significant decrease in the measured IOP was observed (before CK: 14.22+/-1.64 vs after CK: 12.66+/-2.21, P<.001). The change in IOP readings postoperatively was not correlated with age, sex, keratometric readings, or attempted correction. Despite the limitations due to the small number of patients enrolled in this study, the applanation tonometer appears to underestimate the true IOP after CK.

  18. Measuring Method for Lightning Channel Temperature

    Science.gov (United States)

    Li, X.; Zhang, J.; Chen, L.; Xue, Q.; Zhu, R.

    2016-09-01

    In this paper, we demonstrate the temperature of lightning channel utilizing the theory of lightning spectra and the model of local thermodynamic equilibrium (LTE). The impulse current generator platform (ICGS) was used to simulate the lightning discharge channel, and the spectral energy of infrared spectroscopy (930 nm) and the visible spectroscopy (648.2 nm) of the simulated lightning has been calculated. Results indicate that the peaks of luminous intensity of both infrared and visible spectra increase with the lightning current intensity in range of 5-50 kA. Based on the results, the temperature of the lightning channel is derived to be 6140.8-10424 K. Moreover, the temperature of the channel is approximately exponential to the lightning current intensity, which shows good agreement with that of the natural lightning cases.

  19. Conduction channels at finite bias in single-atom gold contacts

    DEFF Research Database (Denmark)

    Brandbyge, Mads; Kobayashi, Nobuhiko; Tsukada, Masaru

    1999-01-01

    We consider the effect of a finite voltage bias on the conductance of single-atom gold contacts. We employ a nonorthogonal spn-tight-binding Hamiltonian combined with a local charge neutrality assumption. The conductance and charge distributions for finite bias are calculated using the nonequilib......We consider the effect of a finite voltage bias on the conductance of single-atom gold contacts. We employ a nonorthogonal spn-tight-binding Hamiltonian combined with a local charge neutrality assumption. The conductance and charge distributions for finite bias are calculated using...... of the eigenchannels projected onto tight-binding orbitals. We find a single almost fully transmitting channel with mainly s character for low bias while for high bias this channel becomes less transmitting and additional channels involving only d orbitals start to conduct....

  20. Note: A dual-channel sensor for dew point measurement based on quartz crystal microbalance

    Science.gov (United States)

    Li, Ning; Meng, Xiaofeng; Nie, Jing

    2017-05-01

    A new sensor with dual-channel was designed for eliminating the temperature effect on the frequency measurement of the quartz crystal microbalance (QCM) in dew point detection. The sensor uses active temperature control, produces condensation on the surface of QCM, and then detects the dew point. Both the single-channel and the dual-channel methods were conducted based on the device. The measurement error of the single-channel method was less than 0.5 °C at the dew point range of -2 °C-10 °C while the dual-channel was 0.3 °C. The results showed that the dual-channel method was able to eliminate the temperature effect and yield better measurement accuracy.

  1. Measuring Thermal Conductivity at LH2 Temperatures

    Science.gov (United States)

    Selvidge, Shawn; Watwood, Michael C.

    2004-01-01

    For many years, the National Institute of Standards and Technology (NIST) produced reference materials for materials testing. One such reference material was intended for use with a guarded hot plate apparatus designed to meet the requirements of ASTM C177-97, "Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus." This apparatus can be used to test materials in various gaseous environments from atmospheric pressure to a vacuum. It allows the thermal transmission properties of insulating materials to be measured from just above ambient temperature down to temperatures below liquid hydrogen. However, NIST did not generate data below 77 K temperature for the reference material in question. This paper describes a test method used at NASA's Marshall Space Flight Center (MSFC) to optimize thermal conductivity measurements during the development of thermal protection systems. The test method extends the usability range of this reference material by generating data at temperatures lower than 77 K. Information provided by this test is discussed, as are the capabilities of the MSFC Hydrogen Test Facility, where advanced methods for materials testing are routinely developed and optimized in support of aerospace applications.

  2. Hydralazine-induced vasodilation involves opening of high conductance Ca2+-activated K+ channels

    DEFF Research Database (Denmark)

    Bang, Lone; Nielsen-Kudsk, J E; Gruhn, N

    1998-01-01

    The purpose of this study was to investigate whether high conductance Ca2+-activated K+ channels (BK(Ca)) are mediating the vasodilator action of hydralazine. In isolated porcine coronary arteries, hydralazine (1-300 microM), like the K+ channel opener levcromakalim, preferentially relaxed......M) suppressed this response by 82% (P opening of BK(Ca) takes part in the mechanism whereby...

  3. Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel*

    OpenAIRE

    Fischer, Audrey; Sambashivan, Shilpa; Brunger, Axel T.; Montal, Mauricio

    2011-01-01

    Botulinum neurotoxin, the causative agent of the paralytic disease botulism, is an endopeptidase composed of a catalytic domain (or light chain (LC)) and a heavy chain (HC) encompassing the translocation domain (TD) and receptor-binding domain. Upon receptor-mediated endocytosis, the LC and TD are proposed to undergo conformational changes in the acidic endocytic environment resulting in the formation of an LC protein-conducting TD channel. The mechanism of channel formation and the conformat...

  4. Conduction velocity is regulated by sodium channel inactivation in unmyelinated axons innervating the rat cranial meninges.

    Science.gov (United States)

    De Col, Roberto; Messlinger, Karl; Carr, Richard W

    2008-02-15

    Axonal conduction velocity varies according to the level of preceding impulse activity. In unmyelinated axons this typically results in a slowing of conduction velocity and a parallel increase in threshold. It is currently held that Na(+)-K(+)-ATPase-dependent axonal hyperpolarization is responsible for this slowing but this has long been equivocal. We therefore examined conduction velocity changes during repetitive activation of single unmyelinated axons innervating the rat cranial meninges. In direct contradiction to the currently accepted postulate, Na(+)-K(+)-ATPase blockade actually enhanced activity-induced conduction velocity slowing, while the degree of velocity slowing was curtailed in the presence of lidocaine (10-300 microm) and carbamazepine (30-500 microm) but not tetrodotoxin (TTX, 10-80 nm). This suggests that a change in the number of available sodium channels is the most prominent factor responsible for activity-induced changes in conduction velocity in unmyelinated axons. At moderate stimulus frequencies, axonal conduction velocity is determined by an interaction between residual sodium channel inactivation following each impulse and the retrieval of channels from inactivation by a concomitant Na(+)-K(+)-ATPase-mediated hyperpolarization. Since the process is primarily dependent upon sodium channel availability, tracking conduction velocity provides a means of accessing relative changes in the excitability of nociceptive neurons.

  5. Long-Range Channel Measurements on Small Terminal Antennas Using Optics

    DEFF Research Database (Denmark)

    Yanakiev, Boyan; Nielsen, Jesper Ødum; Christensen, Morten

    2012-01-01

    In this paper, details are given on a novel measurement device for radio propagation-channel measurements. To avoid measurement errors due to the conductive cables on small terminal antennas, as well as to improve the handling of the prototypes under investigation, an optical measurement device has...

  6. Theory and simulation of ion conduction in the pentameric GLIC channel.

    Science.gov (United States)

    Zhu, Fangqiang; Hummer, Gerhard

    2012-10-09

    GLIC is a bacterial member of the large family of pentameric ligand-gated ion channels. To study ion conduction through GLIC and other membrane channels, we combine the one-dimensional potential of mean force for ion passage with a Smoluchowski diffusion model, making it possible to calculate single-channel conductance in the regime of low ion concentrations from all-atom molecular dynamics (MD) simulations. We then perform MD simulations to examine sodium ion conduction through the GLIC transmembrane pore in two systems with different bulk ion concentrations. The ion potentials of mean force, calculated from umbrella sampling simulations with Hamiltonian replica exchange, reveal a major barrier at the hydrophobic constriction of the pore. The relevance of this barrier for ion transport is confirmed by a committor function that rises sharply in the barrier region. From the free evolution of Na(+) ions starting at the barrier top, we estimate the effective diffusion coefficient in the barrier region, and subsequently calculate the conductance of the pore. The resulting diffusivity compares well with the position-dependent ion diffusion coefficient obtained from restrained simulations. The ion conductance obtained from the diffusion model agrees with the value determined via a reactive-flux rate calculation. Our results show that the conformation in the GLIC crystal structure, with an estimated conductance of ~1 picosiemens at 140 mM ion concentration, is consistent with a physiologically open state of the channel.

  7. A conductance maximum observed in an inward-rectifier potassium channel

    OpenAIRE

    1994-01-01

    One prediction of a multi-ion pore is that its conductance should reach a maximum and then begin to decrease as the concentration of permeant ion is raised equally on both sides of the membrane. A conductance maximum has been observed at the single-channel level in gramicidin and in a Ca(2+)-activated K+ channel at extremely high ion concentration (> 1,000 mM) (Hladky, S. B., and D. A. Haydon. 1972. Biochimica et Biophysica Acta. 274:294-312; Eisenmam, G., J. Sandblom, and E. Neher. 1977. In ...

  8. Beltless translocation domain of botulinum neurotoxin A embodies a minimum ion-conductive channel.

    Science.gov (United States)

    Fischer, Audrey; Sambashivan, Shilpa; Brunger, Axel T; Montal, Mauricio

    2012-01-13

    Botulinum neurotoxin, the causative agent of the paralytic disease botulism, is an endopeptidase composed of a catalytic domain (or light chain (LC)) and a heavy chain (HC) encompassing the translocation domain (TD) and receptor-binding domain. Upon receptor-mediated endocytosis, the LC and TD are proposed to undergo conformational changes in the acidic endocytic environment resulting in the formation of an LC protein-conducting TD channel. The mechanism of channel formation and the conformational changes in the toxin upon acidification are important but less well understood aspects of botulinum neurotoxin intoxication. Here, we have identified a minimum channel-forming truncation of the TD, the "beltless" TD, that forms transmembrane channels with ion conduction properties similar to those of the full-length TD. At variance with the holotoxin and the HC, channel formation for both the TD and the beltless TD occurs independent of a transmembrane pH gradient. Furthermore, acidification in solution induces moderate secondary structure changes. The subtle nature of the conformational changes evoked by acidification on the TD suggests that, in the context of the holotoxin, larger structural rearrangements and LC unfolding occur preceding or concurrent to channel formation. This notion is consistent with the hypothesis that although each domain of the holotoxin functions individually, each domain serves as a chaperone for the others.

  9. Zinc-dependent multi-conductance channel activity in mitochondria isolated from ischemic brain.

    Science.gov (United States)

    Bonanni, Laura; Chachar, Mushtaque; Jover-Mengual, Teresa; Li, Hongmei; Jones, Adrienne; Yokota, Hidenori; Ofengeim, Dimitry; Flannery, Richard J; Miyawaki, Takahiro; Cho, Chang-Hoon; Polster, Brian M; Pypaert, Marc; Hardwick, J Marie; Sensi, Stefano L; Zukin, R Suzanne; Jonas, Elizabeth A

    2006-06-21

    Transient global ischemia is a neuronal insult that induces delayed cell death. A hallmark event in the early post-ischemic period is enhanced permeability of mitochondrial membranes. The precise mechanisms by which mitochondrial function is disrupted are, as yet, unclear. Here we show that global ischemia promotes alterations in mitochondrial membrane contact points, a rise in intramitochondrial Zn2+, and activation of large, multi-conductance channels in mitochondrial outer membranes by 1 h after insult. Mitochondrial channel activity was associated with enhanced protease activity and proteolytic cleavage of BCL-xL to generate its pro-death counterpart, deltaN-BCL-xL. The findings implicate deltaN-BCL-xL in large, multi-conductance channel activity. Consistent with this, large channel activity was mimicked by introduction of recombinant deltaN-BCL-xL to control mitochondria and blocked by introduction of a functional BCL-xL antibody to post-ischemic mitochondria via the patch pipette. Channel activity was also inhibited by nicotinamide adenine dinucleotide, indicative of a role for the voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane. In vivo administration of the membrane-impermeant Zn2+ chelator CaEDTA before ischemia or in vitro application of the membrane-permeant Zn2+ chelator tetrakis-(2-pyridylmethyl) ethylenediamine attenuated channel activity, suggesting a requirement for Zn2+. These findings reveal a novel mechanism by which ischemic insults disrupt the functional integrity of the outer mitochondrial membrane and implicate deltaN-BCL-xL and VDAC in the large, Zn2+-dependent mitochondrial channels observed in post-ischemic hippocampal mitochondria.

  10. The modelling and measurement of super-conducting rock joints

    International Nuclear Information System (INIS)

    Barton, N.; Makurat, A.; Vik, G.; Loset, F.

    1985-01-01

    Rock joints exhibiting exceptionally high conductivity have been responsible for severe inflows (10-50 m 3 /min.) and flooding in recent Norwegian tunneling projects. These events may be explained by channeling of flow in partially outwashed mineral fillings, associated with deep weathering in ancient basement rocks. There is also evidence to suggest extensional strain with consistent relationships to regional faulting patterns (Selmer-Olsen 1981). Hydraulic fractures making connection with joint systems that are sheared as a result of increased fluid pressure, has been deduced as the mechanism explaining unusually large fluid losses in the geothermal project in Cornwall, England (Pine and Batchelor, 1984). Such mechanisms also introduce uncertainty into water flood and MHF stimulation treatment of fractured oil and gas reservoirs, particularly when principal stress and joint orientations are poorly understood due to coring and stress measurement problems in weak, overstressed reservoir rocks. The possibility of permanent disposal of nuclear waste in crystalline rock, has also focussed attention on highly conductive (''super-conducting'') joints in nuclear waste programmes in Canada, the USA and in Europe. The bi-modal distributions of joint spacing, continuity, apertures and conductivities resulting from the discovery of super-conducting joints has important implications for the location of planned repositories, due to their dramatic impact on potential transport times. In the laboratory a class of super-conducting joints can be created by shear displacement that causes dilation when shearing non-planar features. Recent biaxial shear testing of rock joints recovered in jointed core has identified a strong coupling of conductivity and shear displacement. The theoretical predictions of constitutive relationships for coupled flow in rock joints (Barton et al. 1985) have been broadly verified

  11. Up-Regulatory Effects of Curcumin on Large Conductance Ca2+-Activated K+ Channels

    Science.gov (United States)

    Hei, Hongya; Li, Fangping; Wang, Yunman; Peng, Wen; Zhang, Xuemei

    2015-01-01

    Large conductance Ca2+-activated potassium channels (BK) are targets for research that explores therapeutic means to various diseases, owing to the roles of the channels in mediating multiple physiological processes in various cells and tissues. We investigated the pharmacological effects of curcumin, a compound isolated from the herb Curcuma longa, on BK channels. As recorded by whole-cell patch-clamp, curcumin increased BK (α) and BK (α+β1) currents in transfected HEK293 cells as well as the current density of BK in A7r5 smooth muscle cells in a dose-dependent manner. By incubating with curcumin for 24 hours, the current density of exogenous BK (α) in HEK293 cells and the endogenous BK in A7r5 cells were both enhanced notably, though the steady-state activation of the channels did not shift significantly, except for BK (α+β1). Curcumin up-regulated the BK protein expression without changing its mRNA level in A7r5 cells. The surface expression and the half-life of BK channels were also increased by curcumin in HEK293 cells. These effects of curcumin were abolished by MG-132, a proteasome inhibitor. Curcumin also increased ERK 1/2 phosphorylation, while inhibiting ERK by U0126 attenuated the curcumin-induced up-regulation of BK protein expression. We also observed that the curcumin-induced relaxation in the isolated rat aortic rings was significantly attenuated by paxilline, a BK channel specific blocker. These results show that curcumin enhances the activity of the BK channels by interacting with BK directly as well as enhancing BK protein expression through inhibiting proteasomal degradation and activating ERK signaling pathway. The findings suggest that curcumin is a potential BK channel activator and provide novel insight into its complicated pharmacological effects and the underlying mechanisms. PMID:26672753

  12. Up-Regulatory Effects of Curcumin on Large Conductance Ca2+-Activated K+ Channels.

    Directory of Open Access Journals (Sweden)

    Qijing Chen

    Full Text Available Large conductance Ca2+-activated potassium channels (BK are targets for research that explores therapeutic means to various diseases, owing to the roles of the channels in mediating multiple physiological processes in various cells and tissues. We investigated the pharmacological effects of curcumin, a compound isolated from the herb Curcuma longa, on BK channels. As recorded by whole-cell patch-clamp, curcumin increased BK (α and BK (α+β1 currents in transfected HEK293 cells as well as the current density of BK in A7r5 smooth muscle cells in a dose-dependent manner. By incubating with curcumin for 24 hours, the current density of exogenous BK (α in HEK293 cells and the endogenous BK in A7r5 cells were both enhanced notably, though the steady-state activation of the channels did not shift significantly, except for BK (α+β1. Curcumin up-regulated the BK protein expression without changing its mRNA level in A7r5 cells. The surface expression and the half-life of BK channels were also increased by curcumin in HEK293 cells. These effects of curcumin were abolished by MG-132, a proteasome inhibitor. Curcumin also increased ERK 1/2 phosphorylation, while inhibiting ERK by U0126 attenuated the curcumin-induced up-regulation of BK protein expression. We also observed that the curcumin-induced relaxation in the isolated rat aortic rings was significantly attenuated by paxilline, a BK channel specific blocker. These results show that curcumin enhances the activity of the BK channels by interacting with BK directly as well as enhancing BK protein expression through inhibiting proteasomal degradation and activating ERK signaling pathway. The findings suggest that curcumin is a potential BK channel activator and provide novel insight into its complicated pharmacological effects and the underlying mechanisms.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-25

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

  14. Measure of Development for Student Conduct Administration

    Science.gov (United States)

    Nelson, Adam Ross

    2017-01-01

    Student Conduct Administration (SCA) is one of many names for the processes and procedures through which colleges and universities manage student behavior. Despite the accessibility of quasi-experimental design (QED) in the study of education (Schlotter, Schwerdt, & Woessman, 2011), the existing scholarship has yet to generate strong empirical…

  15. Purification of charybdotoxine, a specific inhibitor of the high-conductance Ca2+-activated K+ channel

    International Nuclear Information System (INIS)

    Smith, C.; Phillips, M.; Miller, C.

    1986-01-01

    Charybdotoxim is a high-affinity specific inhibitor of the high-conductance Ca 2+ -activated K + channel found in the plasma membranes of many vertebrate cell types. Using Ca 2+ -activated K + channels reconstituted into planar lipid bilayer membranes as an assay, the authors have purified the toxin from the venom of the scorpion Leiurus quinquestriatus by a two-step procedure involving chromatofocusing on SP-Sephadex, followed by reversed-phase high-performance liquid chromatography. Charybdotoxin is shown to be a highly basic protein with a mass of 10 kDa. Under the standard assay conditions, the purified toxin inhibits the Ca 2+ -activated K + channel with an apparent dissociation constant of 3.5 nM. The protein is unusually stable, with inhibitory potency being insensitive to boiling or exposure to organic solvents. The toxin's activity is sensitive to chymotrypsin treatment and to acylation of lysine groups. The protein may be radioiodinated without loss of activity

  16. Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction.

    Directory of Open Access Journals (Sweden)

    Kota Kasahara

    Full Text Available The mechanism of ion conduction by potassium channels is one of the central issues in physiology. In particular, it is still unclear how the ion concentration and the membrane voltage drive ion conduction. We have investigated the dynamics of the ion conduction processes in the Kv1.2 pore domain, by molecular dynamics (MD simulations with several different voltages and ion concentrations. By focusing on the detailed ion movements through the pore including selectivity filter (SF and cavity, we found two major conduction mechanisms, called the III-IV-III and III-II-III mechanisms, and the balance between the ion concentration and the voltage determines the mechanism preference. In the III-IV-III mechanism, the outermost ion in the pore is pushed out by a new ion coming from the intracellular fluid, and four-ion states were transiently observed. In the III-II-III mechanism, the outermost ion is pulled out first, without pushing by incoming ions. Increases in the ion concentration and voltage accelerated ion conductions, but their mechanisms were different. The increase in the ion concentrations facilitated the III-IV-III conductions, while the higher voltages increased the III-II-III conductions, indicating that the pore domain of potassium channels permeates ions by using two different driving forces: a push by intracellular ions and a pull by voltage.

  17. Evaluation of Cow Milk Electrical Conductivity Measurements

    Directory of Open Access Journals (Sweden)

    Constantin Gavan

    2017-11-01

    Full Text Available The efficiency of subclinical mastitis diagnosis using an electrical conductivity (EC meter was evaluated in the dairy farm of Agricultural Research and Development Station ( ARDS Simnic Craiova. The results were compared with those obtained by using the California Mastitis Test (CMT and the Somatic Cell Count (SCC.The milk quarter samples ( 1176 from Holstein Friesian cows were analyzed between September and December 2015. The EC evaluation with  the EC meter  ,showed a high proportion of results differing from SCC and CMT results. The CMT still shows to be the most accessible and efficient test in comparison to the EC meter tested.

  18. MIMO channel measurements using optical links on small mobile terminals

    DEFF Research Database (Denmark)

    Yanakiev, Boyan; Nielsen, Jesper Ødum; Pedersen, Gert Frølund

    2010-01-01

    This paper looks at a novel measurement device for propagation channel measurements using a fiber optic link. Although the idea of using optical links is not new, most of the developments in the area are either too big [5], short range [6] or suitable for anechoic chamber only [7]. The device...... presented here is specifically designed to fit in a very small volume and is optimized for low power consumption (runs on small battery), thus imitating the phone electronics. It can be used for anechoic chamber measurements, however it is designed for long range channel sounding measurements....

  19. Solid Layer Thermal-conductivity Measurement Techniques

    Science.gov (United States)

    1994-03-01

    deposited on the sample, and the absorption of laser radiation. Temperature-measurement tools include thermocouples, infrared (IR) pyrometers , and...A, Nishimura H, and Sawada T (1990), Laser-Induc~d Surface Acoustic Waves and Photothc:rmal Surfitce Gratings Generated by Crossing Two Pulsed

  20. Understanding the conductive channel evolution in Na:WO3-x-based planar devices

    Science.gov (United States)

    Shang, Dashan; Li, Peining; Wang, Tao; Carria, Egidio; Sun, Jirong; Shen, Baogen; Taubner, Thomas; Valov, Ilia; Waser, Rainer; Wuttig, Matthias

    2015-03-01

    An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO3-x) films on a soda-lime glass substrate, from which Na+ diffuses into the WO3-x films during the deposition. The entire process of Na+ migration driven by an alternating electric field is visualized in the Na-doped WO3-x films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na+ mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices.An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO3-x) films on a soda-lime glass substrate, from which Na+ diffuses into the WO3-x films during the deposition. The entire process of Na+ migration driven by an alternating electric field is visualized in the Na-doped WO3-x films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the

  1. A possible CO2 conducting and concentrating mechanism in plant stomata SLAC1 channel.

    Directory of Open Access Journals (Sweden)

    Qi-Shi Du

    Full Text Available BACKGROUND: The plant SLAC1 is a slow anion channel in the membrane of stomatal guard cells, which controls the turgor pressure in the aperture-defining guard cells, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought, high levels of carbon dioxide, and bacterial invasion. Recent study demonstrated that bicarbonate is a small-molecule activator of SLAC1. Higher CO(2 and HCO(3(- concentration activates S-type anion channel currents in wild-type Arabidopsis guard cells. Based on the SLAC1 structure a theoretical model is derived to illustrate the activation of bicarbonate to SLAC1 channel. Meanwhile a possible CO(2 conducting and concentrating mechanism of the SLAC1 is proposed. METHODOLOGY: The homology structure of Arabidopsis thaliana SLAC1 (AtSLAC1 provides the structural basis for study of the conducting and concentrating mechanism of carbon dioxide in SLAC1 channels. The pK(a values of ionizable amino acid side chains in AtSLAC1 are calculated using software PROPKA3.0, and the concentration of CO(2 and anion HCO(3(- are computed based on the chemical equilibrium theory. CONCLUSIONS: The AtSLAC1 is modeled as a five-region channel with different pH values. The top and bottom layers of channel are the alkaline residue-dominated regions, and in the middle of channel there is the acidic region surrounding acidic residues His332. The CO(2 concentration is enhanced around 10(4 times by the pH difference between these regions, and CO(2 is stored in the hydrophobic region, which is a CO(2 pool. The pH driven CO(2 conduction from outside to inside balances the back electromotive force and maintain the influx of anions (e.g. Cl(- and NO(3(- from inside to outside. SLAC1 may be a pathway providing CO(2 for photosynthesis in the guard cells.

  2. Decoupling ion conductivity and fluid permeation through optimizing hydrophilic channel morphology

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Peter Po-Jen, E-mail: pjchu@cc.ncu.edu.tw; Fang, Yu-Shin; Tseng, Yu-Chen [Department of Chemistry, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan (R.O.C.) (China)

    2016-05-18

    Approaches to improve membrane ion conductivity usually leads to higher degree of swelling, more serious fuel cross-over and often sacrificed membrane mechanical strength. Preserving all three main membrane properties is a tough challenge in searching high ion conducting fuel cell membrane. The long standing dilemma is resolved by decoupling ion conduction and fluid permeation property by creating optimized channel morphology using external electric field poling. Success of this approach is demonstrated in the proton conducting membrane composed of poly(ether sulfones) (PES) and sulfonated poly(ether ether ketone) (sPEEK, degree of sulfonation=50%) composites prepared under electric field poling condition. The external field enhanced the aromatic chain ordering from both sPEEK and PES and improved the miscibility. This induced interaction is conducive to the formation of more densely packed amorphous domains that eventually leads to preferentially ordered hydrophilic proton conducting channels having a average dimension (3 nm) smaller than that in generic sPEEK or Nafion. The narrower but more ordered channel displayed much lower methanol permeability (3.17×10{sup −7} cm{sup 2}/s), and lower swelling ratio (31.20%), while the conductivity (~10{sup −1} S/cm) is higher than that of Nafion, or sPEEK at higher (64%) degree of sulfonation. The composite is chemically stable and highly durable with improved membrane mechanical strength. Nearly 50% increase of DMFC power output is observed using this membrane, and the best power density is recorded at 155 mA/cm{sup 2} (80 °C, 1M Methanol).

  3. Channel capacities versus entanglement measures in multiparty quantum states

    International Nuclear Information System (INIS)

    Sen, Aditi; Sen, Ujjwal

    2010-01-01

    For quantum states of two subsystems, highly entangled states have a higher capacity of transmitting classical as well as quantum information, and vice versa. We show that this is no more the case in general: Quantum capacities of multiaccess channels, motivated by communication in quantum networks, do not have any relation with genuine multiparty entanglement measures. Importantly, the statement is demonstrated for arbitrary multipartite entanglement measures. Along with revealing the structural richness of multiaccess channels, this gives us a tool to classify multiparty quantum states from the perspective of its usefulness in quantum networks, which cannot be visualized by any genuine multiparty entanglement measure.

  4. Top Quark Mass Measurement in Dilepton Channel

    Energy Technology Data Exchange (ETDEWEB)

    Lysak, Roman [Inst. of Experimental Physics, Kosice (Slovak Republic)

    2007-06-01

    We present a measurement of the top quark mass from events produced in p$\\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV, using the Collider Detector at Fermilab. We identify t$\\bar{t}$ candidates where both W bosons from the top quarks decay into leptons (eν, µν, τν) from a data sample of 340 pb-1. The top quark mass is reconstructed in each event separately by the method which draw upon simulated distribution of t$\\bar{t}$ longitudinal momentum in order to extract probability distribution for the top quark mass. Representative distributions, or templates, are constructed from simulated samples of signal and background events, and parametrized to form continuous probability density functions. A likelihood fit incorporating these parametrized templates is then performed on the data sample masses in order to derive a final top quark mass. Measured top quark mass is Mtop = 169.5$+7.7\\atop{-7.2}$(stat.) ± 4.0(syst.) GeV/c2.

  5. Conducted vasoconstriction in rat mesenteric arterioles: role for dihydropyridine-insensitive Ca(2+) channels

    DEFF Research Database (Denmark)

    Gustafsson, F; Andreasen, D; Salomonsson, Max

    2001-01-01

    The aim of this study was to evaluate the role of voltage-operated Ca(2+) channels in the initiation and conduction of vasoconstrictor responses to local micropipette electrical stimulation of rat mesenteric arterioles (28 +/- 1 microm, n = 79) in vivo. Local and conducted (600 microm upstream from...... the pipette) vasoconstriction was not blocked by TTX (1 micromol/l, n = 5), nifedipine, or nimodipine (10 micromol/l, n = 9). Increasing the K(+) concentration of the superfusate to 75 mmol/l did not evoke vasoconstriction, but this depolarizing stimulus reversibly abolished vasoconstrictor responses...

  6. Measurement channel of neutron flow based on software

    International Nuclear Information System (INIS)

    Rivero G, T.; Benitez R, J. S.

    2008-01-01

    The measurement of the thermal power in nuclear reactors is based mainly on the measurement of the neutron flow. The presence of these in the reactor core is associated to neutrons released by the fission reaction of the uranium-235. Once moderate, these neutrons are precursors of new fissions. This process it is known like chain reaction. Thus, the power to which works a nuclear reactor, he is proportional to the number of produced fissions and as these depend on released neutrons, also the power is proportional to the number of present neutrons. The measurement of the thermal power in a reactor is realized with called instruments nuclear channels. To low power (level source), these channels measure the individual counts of detected neutrons, whereas to a medium and high power, they measure the electrical current or fluctuation of the same one that generate the fission neutrons in ionization chambers especially designed to detect neutrons. For the case of TRIGA reactors, the measurement channels of neutron flow use discreet digital electronic technology makes some decades already. Recently new technological tools have arisen that allow developing new versions of nuclear channels of simple form and compacts. The present work consists of the development of a nuclear channel for TRIGA reactors based on the use of the correlated signal of a fission chamber for ample interval. This new measurement channel uses a data acquisition card of high speed and the data processing by software that to the being installed in a computer is created a virtual instrument, with what spreads in real time, in graphic and understandable form for the operator, the power indication to which it operates the nuclear reactor. This system when being based on software, offers a major versatility to realize changes in the signal processing and power monitoring algorithms. The experimental tests of neutronic power measurement show a reliable performance through seven decades of power, with a

  7. Suppression of ion conductance by electro-osmotic flow in nano-channels with weakly overlapping electrical double layers

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-08-01

    Full Text Available This theoretical study investigates the nonlinear ionic current-voltage characteristics of nano-channels that have weakly overlapping electrical double layers. Numerical simulations as well as a 1-D mathematical model are developed to reveal that the electro-osmotic flow (EOF interplays with the concentration-polarization process and depletes the ion concentration inside the channels, thus significantly suppressing the channel conductance. The conductance may be restored at high electrical biases in the presence of recirculating vortices within the channels. As a result of the EOF-driven ion depletion, a limiting-conductance behavior is identified, which is intrinsically different from the classical limiting-current behavior.

  8. Understanding the conductive channel evolution in Na:WO(3-x)-based planar devices.

    Science.gov (United States)

    Shang, Dashan; Li, Peining; Wang, Tao; Carria, Egidio; Sun, Jirong; Shen, Baogen; Taubner, Thomas; Valov, Ilia; Waser, Rainer; Wuttig, Matthias

    2015-04-14

    An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO(3-x)) films on a soda-lime glass substrate, from which Na(+) diffuses into the WO(3-x) films during the deposition. The entire process of Na(+) migration driven by an alternating electric field is visualized in the Na-doped WO(3-x) films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na(+) mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices.

  9. On the channel width-dependence of the thermal conductivity in ultra-narrow graphene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Karamitaheri, Hossein [Department of Electrical Engineering, University of Kashan, Kashan 87317-53153 (Iran, Islamic Republic of); Neophytou, Neophytos, E-mail: N.Neophytou@warwick.ac.uk [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2016-08-08

    The thermal conductivity of low-dimensional materials and graphene nanoribbons, in particular, is limited by the strength of line-edge-roughness scattering. One way to characterize the roughness strength is the dependency of the thermal conductivity on the channel's width in the form W{sup β}. Although in the case of electronic transport, this dependency is very well studied, resulting in W{sup 6} for nanowires and quantum wells and W{sup 4} for nanoribbons, in the case of phonon transport it is not yet clear what this dependence is. In this work, using lattice dynamics and Non-Equilibrium Green's Function simulations, we examine the width dependence of the thermal conductivity of ultra-narrow graphene nanoribbons under the influence of line edge-roughness. We show that the exponent β is in fact not a single well-defined number, but it is different for different parts of the phonon spectrum depending on whether phonon transport is ballistic, diffusive, or localized. The exponent β takes values β < 1 for semi-ballistic phonon transport, values β ≫ 1 for sub-diffusive or localized phonons, and β = 1 only in the case where the transport is diffusive. The overall W{sup β} dependence of the thermal conductivity is determined by the width-dependence of the dominant phonon modes (usually the acoustic ones). We show that due to the long phonon mean-free-paths, the width-dependence of thermal conductivity becomes a channel length dependent property, because the channel length determines whether transport is ballistic, diffusive, or localized.

  10. Determining the effects of thermal conductivity on epoxy molds using profiled cooling channels with metal inserts

    International Nuclear Information System (INIS)

    Altaf, Khurram; Rani, Abdul Ahmad Majdi; Ahmad, Faiz; Baharom, Masri; Raghavan, Vijay R.

    2016-01-01

    Polymer injection molds are generally manufactured with metallic materials, such as tool steel, which provide reliable working of molds and extended service life. The manufacture of injection molds with steel is a prolonged process because of the strength of steel. For a short prototype production run, one of the suitable choices could be the use of aluminum-filled epoxy material, which can produce a functional mold in a short time as compared with a conventionally machined tool. Aluminum-filled epoxy tooling is a good choice for short production runs for engineering applications, yet works best for relatively simple shapes. The advantages in relation to the fabrication of injection molds with epoxy-based materials include time saving in producing the mold, epoxy curing at ambient temperature, and ease of machining and post processing. Nevertheless, one major drawback of epoxy material is its poor thermal conductivity, which results in a relatively longer cooling time for epoxy injection molds. This study investigates some of the innovative ideas for enhancing the thermal conductivity for epoxy molds. The basic concept behind these ideas was to embed a highly thermally conductive metal insert within the mold between cavities with an innovative design of cooling channels called profiled cooling channels. This technique will increase the effective thermal conductivity of the epoxy mold, leading to the reduction in cooling time for the injection molded polymer part. Experimental analysis conducted in the current study also verified that the mold with profiled cooling channels and embedded metal insert has significantly reduced the cooling time

  11. Determining the effects of thermal conductivity on epoxy molds using profiled cooling channels with metal inserts

    Energy Technology Data Exchange (ETDEWEB)

    Altaf, Khurram; Rani, Abdul Ahmad Majdi; Ahmad, Faiz; Baharom, Masri [Mechanical Engineering Dept., Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak (Malaysia); Raghavan, Vijay R. [OYL Manufacturing, Sungai Buloh (Malaysia)

    2016-11-15

    Polymer injection molds are generally manufactured with metallic materials, such as tool steel, which provide reliable working of molds and extended service life. The manufacture of injection molds with steel is a prolonged process because of the strength of steel. For a short prototype production run, one of the suitable choices could be the use of aluminum-filled epoxy material, which can produce a functional mold in a short time as compared with a conventionally machined tool. Aluminum-filled epoxy tooling is a good choice for short production runs for engineering applications, yet works best for relatively simple shapes. The advantages in relation to the fabrication of injection molds with epoxy-based materials include time saving in producing the mold, epoxy curing at ambient temperature, and ease of machining and post processing. Nevertheless, one major drawback of epoxy material is its poor thermal conductivity, which results in a relatively longer cooling time for epoxy injection molds. This study investigates some of the innovative ideas for enhancing the thermal conductivity for epoxy molds. The basic concept behind these ideas was to embed a highly thermally conductive metal insert within the mold between cavities with an innovative design of cooling channels called profiled cooling channels. This technique will increase the effective thermal conductivity of the epoxy mold, leading to the reduction in cooling time for the injection molded polymer part. Experimental analysis conducted in the current study also verified that the mold with profiled cooling channels and embedded metal insert has significantly reduced the cooling time.

  12. Helicity, membrane incorporation, orientation and thermal stability of the large conductance mechanosensitive ion channel from E. coli

    Science.gov (United States)

    Arkin, I. T.; Sukharev, S. I.; Blount, P.; Kung, C.; Brunger, A. T.

    1998-01-01

    In this report, we present structural studies on the large conductance mechanosensitive ion channel (MscL) from E. coli in detergent micelles and lipid vesicles. Both transmission Fourier transform infrared spectroscopy and circular dichroism (CD) spectra indicate that the protein is highly helical in detergents as well as liposomes. The secondary structure of the proteins was shown to be highly resistant towards denaturation (25-95 degrees C) based on an ellipticity thermal profile. Amide H+/D+ exchange was shown to be extensive (ca. 66%), implying that two thirds of the protein are water accessible. MscL, reconstituted in oriented lipid bilayers, was shown to possess a net bilayer orientation using dichroic ratios measured by attenuated total-reflection Fourier transform infrared spectroscopy. Here, we present and discuss this initial set of structural data on this new family of ion-channel proteins.

  13. Bioinspired Ultrastrong Solid Electrolytes with Fast Proton Conduction along 2D Channels.

    Science.gov (United States)

    He, Guangwei; Xu, Mingzhao; Zhao, Jing; Jiang, Shengtao; Wang, Shaofei; Li, Zhen; He, Xueyi; Huang, Tong; Cao, Moyuan; Wu, Hong; Guiver, Michael D; Jiang, Zhongyi

    2017-07-01

    Solid electrolytes have attracted much attention due to their great prospects in a number of energy- and environment-related applications including fuel cells. Fast ion transport and superior mechanical properties of solid electrolytes are both of critical significance for these devices to operate with high efficiency and long-term stability. To address a common tradeoff relationship between ionic conductivity and mechanical properties, electrolyte membranes with proton-conducting 2D channels and nacre-inspired architecture are reported. An unprecedented combination of high proton conductivity (326 mS cm -1 at 80 °C) and superior mechanical properties (tensile strength of 250 MPa) are achieved due to the integration of exceptionally continuous 2D channels and nacre-inspired brick-and-mortar architecture into one materials system. Moreover, the membrane exhibits higher power density than Nafion 212 membrane, but with a comparative weight of only ≈0.1, indicating potential savings in system weight and cost. Considering the extraordinary properties and independent tunability of ion conduction and mechanical properties, this bioinspired approach may pave the way for the design of next-generation high-performance solid electrolytes with nacre-like architecture. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Multi-channel temperature measurement system for automotive battery stack

    Science.gov (United States)

    Lewczuk, Radoslaw; Wojtkowski, Wojciech

    2017-08-01

    A multi-channel temperature measurement system for monitoring of automotive battery stack is presented in the paper. The presented system is a complete battery temperature measuring system for hybrid / electric vehicles that incorporates multi-channel temperature measurements with digital temperature sensors communicating through 1-Wire buses, individual 1-Wire bus for each sensor for parallel computing (parallel measurements instead of sequential), FPGA device which collects data from sensors and translates it for CAN bus frames. CAN bus is incorporated for communication with car Battery Management System and uses additional CAN bus controller which communicates with FPGA device through SPI bus. The described system can parallel measure up to 12 temperatures but can be easily extended in the future in case of additional needs. The structure of the system as well as particular devices are described in the paper. Selected results of experimental investigations which show proper operation of the system are presented as well.

  15. Cross correlation measurement of low frequency conductivity noise

    Science.gov (United States)

    Jain, Aditya Kumar; Nigudkar, Himanshu; Chakraborti, Himadri; Udupa, Aditi; Gupta, Kantimay Das

    2018-04-01

    In order to study the low frequency noise(1/f noise)an experimental technique based on cross correlation of two channels is presented. In this method the device under test (DUT)is connected to the two independently powered preamplifiers in parallel. The amplified signals from the two preamplifiers are fed to two channels of a digitizer. Subsequent data processing largelyeliminates the uncorrelated noise of the two channels. This method is tested for various commercial carbon/metal film resistors by measuring equilibrium thermal noise (4kBTR). The method is then modified to study the non-equilibrium low frequency noise of heterostructure samples using fiveprobe configuration. Five contact probes allow two parts of the sample to become two arms of a balanced bridge. This configuration helps in suppressing the effect of power supply fluctuations, bath temperature fluctuations and contact resistances.

  16. Molecular and functional expression of high conductance Ca 2+ activated K+ channels in the eel intestinal epithelium

    DEFF Research Database (Denmark)

    Lionetto, Maria G; Rizzello, Antonia; Giordano, Maria E

    2008-01-01

    Several types of K(+) channels have been identified in epithelial cells. Among them high conductance Ca(2+)-activated K(+) channels (BK channels) are of relevant importance for their involvement in regulatory volume decrease (RVD) response following hypotonic stress. The aim of the present work...... was to investigate the functional and molecular expression of BK in the eel intestine, which is a useful experimental model for cell volume regulation research. In the present paper using rat BK channel-specific primer, a RT-PCR signal of 696 pb cDNA was detected in eel intestine, whole nucleotide sequence showed...... high similarity (83%) to the alpha subunit of BK channel family. BK channel protein expression was verified by immunoblotting and confocal microscopy, while the functional role of BK channels in epithelial ion transport mechanisms and cell volume regulation was examined by electrophysiological...

  17. Channel flow structure measurements using particle image velocimetry

    International Nuclear Information System (INIS)

    Norazizi Mohamed; Noraeini Mokhtar; Aziz Ibrahim; Ramli Abu Hassan

    1996-01-01

    Two different flow structures in a laboratory channel were examined using a flow visualization technique, known as Particle Image Velocimetry (PIV). The first channel flow structure was that of a steady flow over a horizontal channel bottom. Photographs of particle displacements were taken in the boundary layer in a plane parallel to the flow. These photographs were analyzed to give simultaneous measurements of two components of the velocity at hundreds of points in the plane. Averaging these photographs gave the velocity profile a few millimeters from the bottom of the channel to the water surface. The results gave good agreement with the known boundary layer theory. This technique is extended to the study of the structure under a progressive wave in the channel. A wavelength of the propagating wave is divided into sections by photographing it continously for a number of frames. Each frame is analyzed and a velocity field under this wave at various phase points were produced with their respective directions. The results show that velocity vectors in a plane under the wave could be achieved instantaneously and in good agreement with the small amplitude wave theory

  18. Measurement of the radioactivity of the channel DTD before Chernobyl

    International Nuclear Information System (INIS)

    Bikit, I.; Slivka, J.; Veskovic, M.; Conkic, Lj.; Marinkov, L.

    1987-01-01

    The activity concentration of long loved fission and corrosion products and natural radionuclides has been measured in a selected part of the Danube-Tisa-Danube channel system which is not receiving liquid effluents from nuclear power plants. The comparison with the activities measured in the river danube did not show statistically significant differences. The results obtained describe the reference level of radioactivity for the evaluation of the contamination of the system caused by the Chernobyl accident. (author)

  19. Distribution, expression and functional effects of small conductance Ca-activated potassium (SK) channels in rat myometrium.

    Science.gov (United States)

    Noble, Karen; Floyd, Rachel; Shmygol, Andre; Shmygol, Anatoly; Mobasheri, A; Wray, Susan

    2010-01-01

    Calcium-activated potassium channels are important in a variety of smooth muscles, contributing to excitability and contractility. In the myometrium previous work has focussed on the large conductance channels (BK), and the role of small conductance channels (SK) has received scant attention, despite the finding that over-expression of an SK channel isoform (SK3) results in uterine dysfunction and delayed parturition. This study therefore characterises the expression of the three SK channel isoforms (SK1-3) in rat myometrium throughout pregnancy and investigates their effect on cytosolic [Ca] and force and compares this with that of BK channels. Consistent expression of all SK isoform transcripts and clear immunostaining of SK1-3 was found. Inhibition of SK1-3 channels (apamin, scyllatoxin) significantly inhibited outward current, caused membrane depolarisation and elicited action potentials in previously quiescent cells. Apamin or scyllatoxin increased the amplitude of [Ca] and force in spontaneously contracting myometrial strips throughout gestation. The functional effect of SK inhibition was larger than that of BK channel inhibition. Thus we show for the first time that SK1-3 channels are expressed and translated throughout pregnancy and contribute to outward current, regulate membrane potential and hence Ca signals in pregnant rat myometrium. They contribute more to quiescence that BK channels. 2009 Elsevier Ltd. All rights reserved.

  20. Highlights in radiation measuring technique's - Serial Micro Channel SMC 2100

    International Nuclear Information System (INIS)

    Kandler, M.; Hoffmann, Ch.

    2002-01-01

    The Serial Micro Channel SMC 2100 offers an ''intelligent stand alone'' electronics for the radiation measuring technique's. First it is designed of being connected to a serial interface RS232 of a PC. With a RS485 serial interface on a PC, a network structure can be generated. It has all functional modules which are necessary for the measurement of detector signals. Hence it is possible to directly connect any detector for radiation measurement to a PC, laptop, or notebook. All variations can be operated without PC support too. It has a modular structure and consists of two blocks, the functional modules and the basic modules. The Serial Micro Channel SMC 2100 may be directly coupled to a detector, which therefore makes the realisation of an ''intelligent radiation detector'' with serial link RS232 or RS485. (orig.)

  1. Effect of Skeletal Muscle Na+ Channel Delivered Via a Cell Platform on Cardiac Conduction and Arrhythmia Induction

    NARCIS (Netherlands)

    Boink, Gerard J. J.; Lu, Jia; Driessen, Helen E.; Duan, Lian; Sosunov, Eugene A.; Anyukhovsky, Evgeny P.; Shlapakova, Iryna N.; Lau, David H.; Rosen, Tove S.; Danilo, Peter; Jia, Zhiheng; Ozgen, Nazira; Bobkov, Yevgeniy; Guo, Yuanjian; Brink, Peter R.; Kryukova, Yelena; Robinson, Richard B.; Entcheva, Emilia; Cohen, Ira S.; Rosen, Michael R.

    2012-01-01

    Background-In depolarized myocardial infarct epicardial border zones, the cardiac sodium channel is largely inactivated, contributing to slow conduction and reentry. We have demonstrated that adenoviral delivery of the skeletal muscle Na+ channel (SkM1) to epicardial border zones normalizes

  2. Termination of Vernakalant-Resistant Atrial Fibrillation by Inhibition of Small-Conductance Ca2+-Activated K+ Channels in Pigs

    DEFF Research Database (Denmark)

    Diness, Jonas Goldin; Skibsbye, Lasse; Simó-Vicens, Rafel

    2017-01-01

    Background Evidence has emerged that small-conductance Ca2+-activated K+ (SK) channels constitute a new target for treatment of atrial fibrillation (AF). SK channels are predominantly expressed in the atria as compared with the ventricles. Various marketed antiarrhythmic drugs are limited by vent...

  3. Regional two-dimensional magnetotelluric profile in West Bohemia/Vogtland reveals deep conductive channel into the earthquake swarm region

    Czech Academy of Sciences Publication Activity Database

    Muňoz, G.; Weckmann, U.; Pek, Josef; Kováčiková, Světlana; Klanica, Radek

    2018-01-01

    Roč. 727, March (2018), s. 1-11 Institutional support: RVO:67985530 Keywords : magnetotellurics * West Bohemia * Fogtland * earthquake swarm * conductive channel * fluids Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Volcanology

  4. Study of a large scale neutron measurement channel

    International Nuclear Information System (INIS)

    Amarouayache, Anissa; Ben Hadid, Hayet.

    1982-12-01

    A large scale measurement channel allows the processing of the signal coming from an unique neutronic sensor, during three different running modes: impulses, fluctuations and current. The study described in this note includes three parts: - A theoretical study of the large scale channel and its brief description are given. The results obtained till now in that domain are presented. - The fluctuation mode is thoroughly studied and the improvements to be done are defined. The study of a fluctuation linear channel with an automatic commutation of scales is described and the results of the tests are given. In this large scale channel, the method of data processing is analogical. - To become independent of the problems generated by the use of a an analogical processing of the fluctuation signal, a digital method of data processing is tested. The validity of that method is improved. The results obtained on a test system realized according to this method are given and a preliminary plan for further research is defined [fr

  5. Measurement-based Channel Characterization for 5G Wireless Communications on Campus Scenario

    DEFF Research Database (Denmark)

    Mi, Yang; He, Ruisi; Ai, Bo

    2017-01-01

    The fifth generation (5G) communication has been a hotspot of research in recent years, and both research institutions and industrial enterprises put a lot of interests for 5G communication at some new frequency bands. In this paper, we investigate the radio channels of 5G communications below 6...... GHz according to the requirements and scenarios of 5G communication. Channel measurements were conducted on campus of Beijing Jiaotong University, China at two key optional frequency bands below 6 GHz. By using the measured data, we analyzed key channel parameters at 460MHz and 3.5GHz, such as power...... delay profile, path loss exponent, shadow fading, and delay spread. The results are helpful for the 5G communication system design....

  6. Quantum conductance in electrodeposited nanocontacts and magnetoresistance measurements

    DEFF Research Database (Denmark)

    Elhoussine, F.; Encinas, A.; Mátéfi-Tempfli, Stefan

    2003-01-01

    The conductance and magnetoresistance measurements in magnetic Ni-Ni and Co-Ni nanocontacts prepared by electrodeposition within the pores of a track of track-etched polymer membrane were discussed. At room temperature, Ni-Ni constrictions were found to show broad quantization plateaus of conduct...... of conductance during their dissolution in units of e/h, as expected for ferromagnetic ballistic nanocontacts. The measurement of the positive and negative magnetoresistance in Co-Ni nanocontacts was also elaborated....

  7. Single-shot optical conductivity measurement of dense aluminum plasmas

    International Nuclear Information System (INIS)

    Churina, I. V.; Cho, B.-I.; Bernstein, A.; Stoker, D. S.; Dalton, A.; Symes, D. R.; Ditmire, T.

    2009-01-01

    The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.

  8. Emerging role of cystic fibrosis transmembrane conductance regulator- an epithelial chloride channel in gastrointestinal cancers

    Institute of Scientific and Technical Information of China (English)

    Yuning Hou; Xiaoqing Guan; Zhe Yang; Chunying Li

    2016-01-01

    Cystic fibrosis transmembrane conductance regulator(CFTR), a glycoprotein with 1480 amino acids, has been well established as a chloride channel mainly expressed in the epithelial cells of various tissues and organs such as lungs, sweat glands, gastrointestinal system, and reproductive organs. Although defective CFTR leads to cystic fibrosis, a common genetic disorder in the Caucasian population, there is accumulating evidence that suggests a novel role of CFTR in various cancers, especially in gastroenterological cancers, such as pancreatic cancer and colon cancer. In this review, we summarize the emerging findings that link CFTR with various cancers, with focus on the association between CFTR defects and gastrointestinal cancers as well as the underlying mechanisms. Further study of CFTR in cancer biology may help pave a new way for the diagnosis and treatment of gastrointestinal cancers.

  9. Proton Conductive Channel Optimization in Methanol Resistive Hybrid Hyperbranched Polyamide Proton Exchange Membrane

    Directory of Open Access Journals (Sweden)

    Liying Ma

    2017-12-01

    Full Text Available Based on a previously developed polyamide proton conductive macromolecule, the nano-scale structure of the self-assembled proton conductive channels (PCCs is adjusted via enlarging the nano-scale pore size within the macromolecules. Hyperbranched polyamide macromolecules with different size are synthesized from different monomers to tune the nano-scale pore size within the macromolecules, and a series of hybrid membranes are prepared from these two micromoles to optimize the PCC structure in the proton exchange membrane. The optimized membrane exhibits methanol permeability low to 2.2 × 10−7 cm2/s, while the proton conductivity of the hybrid membrane can reach 0.25 S/cm at 80 °C, which was much higher than the value of the Nafion 117 membrane (0.192 S/cm. By considering the mechanical, dimensional, and the thermal properties, the hybrid hyperbranched polyamide proton exchange membrane (PEM exhibits promising application potential in direct methanol fuel cells (DMFC.

  10. Thermal Conductivity Measurement of Anisotropic Biological Tissue In Vitro

    Science.gov (United States)

    Yue, Kai; Cheng, Liang; Yang, Lina; Jin, Bitao; Zhang, Xinxin

    2017-06-01

    The accurate determination of the thermal conductivity of biological tissues has implications on the success of cryosurgical/hyperthermia treatments. In light of the evident anisotropy in some biological tissues, a new modified stepwise transient method was proposed to simultaneously measure the transverse and longitudinal thermal conductivities of anisotropic biological tissues. The physical and mathematical models were established, and the analytical solution was derived. Sensitivity analysis and experimental simulation were performed to determine the feasibility and measurement accuracy of simultaneously measuring the transverse and longitudinal thermal conductivities. The experimental system was set up, and its measurement accuracy was verified by measuring the thermal conductivity of a reference standard material. The thermal conductivities of the pork tenderloin and bovine muscles were measured using the traditional 1D and proposed methods, respectively, at different temperatures. Results indicate that the thermal conductivities of the bovine muscle are lower than those of the pork tenderloin muscle, whereas the bovine muscle was determined to exhibit stronger anisotropy than the pork tenderloin muscle. Moreover, the longitudinal thermal conductivity is larger than the transverse thermal conductivity for the two tissues and all thermal conductivities increase with the increase in temperature. Compared with the traditional 1D method, results obtained by the proposed method are slightly higher although the relative deviation is below 5 %.

  11. Small-conductance Ca2+-activated potassium type 2 channels regulate the formation of contextual fear memory.

    Directory of Open Access Journals (Sweden)

    Saravana R K Murthy

    Full Text Available Small-conductance, Ca2+ activated K+ channels (SK channels are expressed at high levels in brain regions responsible for learning and memory. In the current study we characterized the contribution of SK2 channels to synaptic plasticity and to different phases of hippocampal memory formation. Selective SK2 antisense-treatment facilitated basal synaptic transmission and theta-burst induced LTP in hippocampal brain slices. Using the selective SK2 antagonist Lei-Dab7 or SK2 antisense probes, we found that hippocampal SK2 channels are critical during two different time windows: 1 blockade of SK2 channels before the training impaired fear memory, whereas, 2 blockade of SK2 channels immediately after the training enhanced contextual fear memory. We provided the evidence that the post-training cleavage of the SK2 channels was responsible for the observed bidirectional effect of SK2 channel blockade on memory consolidation. Thus, Lei-Dab7-injection before training impaired the C-terminal cleavage of SK2 channels, while Lei-Dab7 given immediately after training facilitated the C-terminal cleavage. Application of the synthetic peptide comprising a leucine-zipper domain of the C-terminal fragment to Jurkat cells impaired SK2 channel-mediated currents, indicating that the endogenously cleaved fragment might exert its effects on memory formation by blocking SK2 channel-mediated currents. Our present findings suggest that SK2 channel proteins contribute to synaptic plasticity and memory not only as ion channels but also by additionally generating a SK2 C-terminal fragment, involved in both processes. The modulation of fear memory by down-regulating SK2 C-terminal cleavage might have applicability in the treatment of anxiety disorders in which fear conditioning is enhanced.

  12. Electrical conductivity and magnetic permeability measurement of case hardened steels

    Science.gov (United States)

    Tian, Yong

    2015-03-01

    For case carburized steels, electrical conductivity and magnetic permeability profiles are needed to develop model-based case depth characterization techniques for the purpose of nondestructive quality control. To obtain fast and accurate measurement of these material properties, four-point potential drop approaches are applied on circular-shaped discs cut from steel rings with different case depths. First, a direct current potential drop (DCPD) approach is applied to measure electrical conductivity. Subsequently, an alternating current potential drop (ACPD) approach is used to measure magnetic permeability. Practical issues in measurement design and implementation are discussed. Depth profiles of electrical conductivity and magnetic permeability are reported.

  13. Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons.

    Science.gov (United States)

    Battefeld, Arne; Tran, Baouyen T; Gavrilis, Jason; Cooper, Edward C; Kole, Maarten H P

    2014-03-05

    Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of K(v)7 potassium channels and voltage-gated sodium (Na(v)) channels in the axonal initial segment and nodes of Ranvier. The local biophysical properties of these K(v)7 channels and the functional impact of colocalization with Na(v) channels remain poorly understood. Here, we quantitatively examined K(v)7 channels in myelinated axons of rat neocortical pyramidal neurons using high-resolution confocal imaging and patch-clamp recording. K(v)7.2 and 7.3 immunoreactivity steeply increased within the distal two-thirds of the axon initial segment and was mirrored by the conductance density estimates, which increased from ~12 (proximal) to 150 pS μm(-2) (distal). The axonal initial segment and nodal M-currents were similar in voltage dependence and kinetics, carried by K(v)7.2/7.3 heterotetramers, 4% activated at the resting membrane potential and rapidly activated with single-exponential time constants (~15 ms at 28 mV). Experiments and computational modeling showed that while somatodendritic K(v)7 channels are strongly activated by the backpropagating action potential to attenuate the afterdepolarization and repetitive firing, axonal K(v)7 channels are minimally recruited by the forward-propagating action potential. Instead, in nodal domains K(v)7.2/7.3 channels were found to increase Na(v) channel availability and action potential amplitude by stabilizing the resting membrane potential. Thus, K(v)7 clustering near axonal Na(v) channels serves specific and context-dependent roles, both restraining initiation and enhancing conduction of the action potential.

  14. Electrical conductivity measurement on DKDP Crystals with different deuterated degrees

    International Nuclear Information System (INIS)

    Liu, Baoan; Yin, Xin; Xu, Mingxia; Ji, Shaohua; Zhu, Lili; Zhang, Lisong; Sun, Xun; Xu, Xinguang; Zhao, Minglei; Zhang, Qinghua

    2012-01-01

    Ten DKDP single crystals with deuterated degrees ranging from 0 to 90 % were grown by a rapid growth method. The electrical conductivities of these crystals were measured along a and c directions at room temperature. The electrical conductivity increases with the increase for deuterium content. Also, the electrical conductivities of certain crystals were measured at various temperatures ranging from 20 to 130 C. The values of activation energy decrease as the increase of deuterium content. The present study indicates that the deuterium tunneling frequency is smaller than that of hydrogen, which may be the reason why the variation of electrical conductivity happens after the substitution of hydrogen for deuterium in KDP crystal. (orig.)

  15. Saltatory conduction in unmyelinated axons: Clustering of Na+ channels on lipid rafts allows micro-saltatory conduction in C-fibers

    Directory of Open Access Journals (Sweden)

    Ali eNeishabouri

    2014-10-01

    Full Text Available The action potential (AP, the fundamental signal of the nervous system, is carried by two types of axons: unmyelinated and myelinated fibers. In the former the action potential propagates continuously along the axon as established in large-diameter fibers. In the latter axons the AP jumps along the Nodes of Ranvier – discrete, anatomically specialized regions which contain very high densities of sodium ion (Na + channels. Therefore saltatory conduction is thought as the hallmark of myelinated axons, which enables faster and more reliable propagation of signals than in unmyelinated axons of same outer diameter.Recent molecular anatomy showed that in C-fibers, the very thin (0.1 μm diameter axons of the peripheral nervous system, Nav1.8 channels are clustered together on lipid rafts that float in the cell membrane. This localized concentration of Na+ channels resembles in structure the ion channel organization at the Nodes of Ranvier, yet it is currently unknown whether this translates into equivalent phenomenon of saltatory conduction or related-functional benefits and efficiencies. Therefore, we modeled biophysically realistic unmyelinated axons with both conventional and lipid-raft based organization of Na+ channels. We find that action potentials are reliably conducted in a micro-saltatory fashion along lipid rafts.Comparing APs in unmyelinated fibers with and without lipid rafts did not reveal any significant difference in either the metabolic cost or AP propagation velocity. By investigating the efficiency of AP propagation over Nav1.8 channels, we find however that the specific inactivation properties of these channels significantly increase the metabolic cost of signaling in C-fibers.

  16. Density measurements of microsecond-conduction-time POS plasmas

    International Nuclear Information System (INIS)

    Hinshelwood, D.; Goodrich, P.J.; Weber, B.V.; Commisso, R.J.; Grossmann, J.M.; Kellogg, J.C.

    1993-01-01

    Measurements of the electron density in a coaxial microsecond conduction time plasma opening switch during switch operation are described. Current conduction is observed to cause a radial redistribution of the switch plasma. A local reduction in axial line density of more than an order of magnitude occurs by the time opening begins. This reduction, and the scaling of conduction current with plasma density, indicate that current conduction in this experiment is limited by hydrodynamic effects. It is hypothesized that the density reduction allows the switch to open by an erosion mechanism. Initial numerical modeling efforts have reproduced the principal observed results. A model that predicts accurately the conduction current is presented

  17. Bupivacaine inhibits large conductance, voltage- and Ca2+- activated K+ channels in human umbilical artery smooth muscle cells

    Science.gov (United States)

    Martín, Pedro; Enrique, Nicolás; Palomo, Ana R. Roldán; Rebolledo, Alejandro; Milesi, Veronica

    2012-01-01

    Bupivacaine is a local anesthetic compound belonging to the amino amide group. Its anesthetic effect is commonly related to its inhibitory effect on voltage-gated sodium channels. However, several studies have shown that this drug can also inhibit voltage-operated K+ channels by a different blocking mechanism. This could explain the observed contractile effects of bupivacaine on blood vessels. Up to now, there were no previous reports in the literature about bupivacaine effects on large conductance voltage- and Ca2+-activated K+ channels (BKCa). Using the patch-clamp technique, it is shown that bupivacaine inhibits single-channel and whole-cell K+ currents carried by BKCa channels in smooth muscle cells isolated from human umbilical artery (HUA). At the single-channel level bupivacaine produced, in a concentration- and voltage-dependent manner (IC50 324 µM at +80 mV), a reduction of single-channel current amplitude and induced a flickery mode of the open channel state. Bupivacaine (300 µM) can also block whole-cell K+ currents (~45% blockage) in which, under our working conditions, BKCa is the main component. This study presents a new inhibitory effect of bupivacaine on an ion channel involved in different cell functions. Hence, the inhibitory effect of bupivacaine on BKCa channel activity could affect different physiological functions where these channels are involved. Since bupivacaine is commonly used during labor and delivery, its effects on umbilical arteries, where this channel is highly expressed, should be taken into account. PMID:22688134

  18. Designing of an apparatus to measure ionic conductivity

    International Nuclear Information System (INIS)

    Vignolo Rubio, J.

    1978-01-01

    The main technical features of a rig to measure ionic conductivity in alkali halides are shown. The conductivity also can be measured while the temperature of the sample is rised at a constant rate between room temperature and 350 deg C. This is intended to search for correlations between variations in the ionic conductivity and the thermal annealing of radiation induce defects in these materials. The proportional temperature controller and programmer also allows to stabilize the sample temperature within +-0.1 degC during several hours. Some measurements in KCl (Harshaw) were made in order to check the reliability of the apparatus. (author)

  19. Ionic conductivity measurements of zirconia under pressure using impedance spectroscopy

    International Nuclear Information System (INIS)

    Takebe, H; Sakamoto, D; Ohtaka, O; Fukui, H; Yoshiasa, A; Yamanaka, T; Ota, K; Kikegawa, T

    2002-01-01

    We have set up an electrical conductivity measurement system under high-pressure and high-temperature conditions with a multi-anvil high-pressure apparatus using an AC complex impedance method. With this system, we have successfully measured the electrical conductivity of stabilized ZrO 2 (Y 2 O 3 -ZrO 2 solid solution) under pressures up to 5 GPa in the temperature range from 300 to 1200 K. The electrical conductivities obtained under pressure are compatible with those of previous results measured at ambient pressure

  20. Measurement of the top quark mass in the dilepton channel

    International Nuclear Information System (INIS)

    Grinstein, S.; Mostafa, M.; Piegaia, R.; Alves, G.A.; Carvalho, W.; Maciel, A.K.; Motta, H. da; Oliveira, E.; Santoro, A.; Lima, J.G.; Oguri, V.; Gomez, B.; Hoeneisen, B.; Mooney, P.; Negret, J.P.; Ducros, Y.; Beri, S.B.; Bhatnagar, V.; Kohli, J.M.; Singh, J.B.; Shivpuri, R.K.; Acharya, B.S.; Banerjee, S.; Dugad, S.R.; Gupta, A.; Krishnaswamy, M.R.; Mondal, N.K.; Narasimham, V.S.; Parua, N.; Shankar, H.C.; Park, Y.M.; Choi, S.; Kim, S.K.; Castilla-Valdez, H.; Gonzalez Solis, J.L.; Hernandez-Montoya, R.; Magana-Mendoza, L.; Sanchez-Hernandez, A.; Pawlik, B.; Gavrilov, V.; Gershtein, Y.; Kuleshov, S.; Belyaev, A.; Dudko, L.V.; Ermolov, P.; Karmanov, D.; Leflat, A.; Manankov, V.; Merkin, M.; Shabalina, E.; Abramov, V.; Babintsev, V.V.; Bezzubov, V.A.; Bojko, N.I.; Burtovoi, V.S.; Chekulaev, S.V.; Denisov, S.P.; Dyshkant, A.; Eroshin, O.V.; Evdokimov, V.N.; Galyaev, A.N.; Goncharov, P.I.; Gurzhiev, S.N.; Kostritskiy, A.V.; Kozelov, A.V.; Kozlovsky, E.A.; Mayorov, A.A.; Babukhadia, L.; Davis, K.; Fein, D.; Forden, G.E.; Guida, J.A.; James, E.; Johns, K.; Nang, F.; Narayanan, A.; Rutherfoord, J.; Shupe, M.; Aihara, H.; Barberis, E.; Chen, L.

    1999-01-01

    We report a measurement of the top quark mass using six candidate events for the process p bar p→t bar t+X→l + νbl - bar ν bar b+X, observed in the D0 experiment at the Fermilab p bar p collider. Using maximum likelihood fits to the dynamics of the decays, we measure a mass for the top quark of m t =168.4±12.3(stat)±3.6(syst) Gev. We combine this result with our previous measurement in the t bar t→l+jets channel to obtain m t =172.1±7.1 GeV as the best value of the mass of the top quark measured by D0. copyright 1999 The American Physical Society

  1. D.C. electrical conductivity measurements on ADP single crystals ...

    Indian Academy of Sciences (India)

    Unknown

    Impurity added ADP crystals; density; electrical conductivity measurements. 1. Introduction ... determined by the intrinsic defects caused by thermal fluctuations in the ... beaker (corning glass vessel) and allowed to equilibrate at the desired ...

  2. Measuring Conductance of Phenylenediamine as a Molecular Sensor

    Directory of Open Access Journals (Sweden)

    Taekyeong Kim

    2015-01-01

    Full Text Available We report experimental measurements of molecular conductance as a single molecular sensor by using scanning tunneling microscope-based break-junction (STM-BJ technique. The gap was created after Au atomic point contact was ruptured, and the target molecule was inserted and bonded to the top and bottom electrodes. We successfully measured the conductance for a series of amine-terminated oligophenyl molecules by forming the molecular junctions with Au electrodes. The measured conductance decays exponentially with molecular backbone length, enabling us to detect the type of molecules as a molecular sensor. Furthermore, we demonstrated reversible binary switching in a molecular junction by mechanical control of the gap between the electrodes. Since our method allows us to measure the conductance of a single molecule in ambient conditions, it should open up various practical molecular sensing applications.

  3. A study of frequency effects on conductivity measurements

    International Nuclear Information System (INIS)

    Nurul Ain Ahmad Latif; Mahmood Dollah; Mohd Khidir Kamaron; Suaib Ibrahim

    2010-01-01

    In eddy current testing (ET), different measurement can be carry out through the selection of the test frequency. In conductivity measurement, the selection of eddy current test frequencies permits to select the specific material properties to be measured. The test frequency selected should be sufficient high that eddy current penetration is limited only to fraction of the test material thickness. This paper describes the effects of test frequency on the conductivity measurement. This experiment done by applying different values of test frequency which is 20 kHz, 100 kHz and 1 MHz. (author)

  4. Measuring electric conductivity in liquid metals by eddy current method

    International Nuclear Information System (INIS)

    Zhuravlev, S.P.; Ostrovskij, O.I.; Grigoryan, V.A.

    1982-01-01

    Technique permitting to apply the method of vertiginous currents for investigation of electric conductivity of metal melts in the high temperature range is presented. Interferences affecting accuracy of measurements are specified and ways of their removing are pointed out. Scheme of measuring and design of the facility are described. Results of measuring electric resistance of liquid Fe, Co, Ni obtained for the first time by this method are presented. The data obtained agree with the results of measurements conducted by the method of the rotating magnetic field. Difference in absolute values of electric resistance in parallel experiments for each metal does not exceed 4%

  5. Stability and quench of dual cooling channel cable-in-conduct superconductors

    International Nuclear Information System (INIS)

    Blau, Bertrand

    1999-11-01

    channel NbTi CICCs with full-size ITER geometry. The influence of the central channel perforations on the stability margin of large CICCs is investigated experimentally. Four identical 3.6 m long pieces of NbTi CICC with ITER geometry but central channels with different porosities are used. The porosity ranges from about 50% with a spiral as central channel - like foreseen for the ITER conductors - over two differently perforated tubes with porosities of the order of 10 -2 %, to zero in the case of a smooth tube. All quench and stability tests have been performed in the SULTAN facility. No significant differences in stability between the conductor samples could be found for currents up to 50 kA, whereas at 60 kA a larger stability margin seemed to appear for the conductor with smallest porosity. These results suggest that for the kind of disturbances applied in the experiment and currents exceeding 50 kA the heating induced helium flow starts to become effective in terms of additional thermal stabilization, which is in agreement with the theoretical predictions made with a zero-dimensional analytical model. Premature quenching was observed in many quench experiments. Sudden voltage take-offs far below the expected critical current were observed without displaying any current sharing regime. The quench currents seemed to be determined by the limiting current, which describes the boundary above which only the marginal heat capacity of the strands can be utilized. These results were interpreted as an indication that thermal disturbances are continuously created by current redistribution processes among the strands due to a largely inhomogeneous current distribution over the cable cross section caused mainly by large interstrand contact resistances. The results of the heat slug measurements in combination with two-dimensional model calculations implied that the heat removal capabilities in long dual cooling channel cable-in-conduit conductors are determined only by the

  6. Stability and quench of dual cooling channel cable-in-conduct superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Bertrand [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

    1999-11-01

    cooling channel NbTi CICCs with full-size ITER geometry. The influence of the central channel perforations on the stability margin of large CICCs is investigated experimentally. Four identical 3.6 m long pieces of NbTi CICC with ITER geometry but central channels with different porosities are used. The porosity ranges from about 50% with a spiral as central channel - like foreseen for the ITER conductors - over two differently perforated tubes with porosities of the order of 10{sup -2}%, to zero in the case of a smooth tube. All quench and stability tests have been performed in the SULTAN facility. No significant differences in stability between the conductor samples could be found for currents up to 50 kA, whereas at 60 kA a larger stability margin seemed to appear for the conductor with smallest porosity. These results suggest that for the kind of disturbances applied in the experiment and currents exceeding 50 kA the heating induced helium flow starts to become effective in terms of additional thermal stabilization, which is in agreement with the theoretical predictions made with a zero-dimensional analytical model. Premature quenching was observed in many quench experiments. Sudden voltage take-offs far below the expected critical current were observed without displaying any current sharing regime. The quench currents seemed to be determined by the limiting current, which describes the boundary above which only the marginal heat capacity of the strands can be utilized. These results were interpreted as an indication that thermal disturbances are continuously created by current redistribution processes among the strands due to a largely inhomogeneous current distribution over the cable cross section caused mainly by large interstrand contact resistances. The results of the heat slug measurements in combination with two-dimensional model calculations implied that the heat removal capabilities in long dual cooling channel cable-in-conduit conductors are determined only

  7. Electrical conductivity measurements of aqueous and immobilized potassium hydroxide

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mollerup, Pia Lolk

    2012-01-01

    concentrations was investigated using the van der Pauw method in combination with electrochemical impedance spectroscopy (EIS). Conductivity values as high as 2.7 S cm−1 for 35 wt%, 2.9 S cm−1 for 45 wt%, and 2.8 S cm−1 for 55 wt% concentrated aqueous solutions were measured at 200 °C. Micro- and nano-porous...... solid pellets were produced and used to immobilize aqueous KOH solutions. These are intended to operate as ion-conductive diaphragms (electrolytes) in alkaline electrolysis cells, offering high conductivity and corrosion resistance. The conductivity of immobilized KOH has been determined by the same...

  8. Non-Contact Conductivity Measurement for Automated Sample Processing Systems

    Science.gov (United States)

    Beegle, Luther W.; Kirby, James P.

    2012-01-01

    A new method has been developed for monitoring and control of automated sample processing and preparation especially focusing on desalting of samples before analytical analysis (described in more detail in Automated Desalting Apparatus, (NPO-45428), NASA Tech Briefs, Vol. 34, No. 8 (August 2010), page 44). The use of non-contact conductivity probes, one at the inlet and one at the outlet of the solid phase sample preparation media, allows monitoring of the process, and acts as a trigger for the start of the next step in the sequence (see figure). At each step of the muti-step process, the system is flushed with low-conductivity water, which sets the system back to an overall low-conductivity state. This measurement then triggers the next stage of sample processing protocols, and greatly minimizes use of consumables. In the case of amino acid sample preparation for desalting, the conductivity measurement will define three key conditions for the sample preparation process. First, when the system is neutralized (low conductivity, by washing with excess de-ionized water); second, when the system is acidified, by washing with a strong acid (high conductivity); and third, when the system is at a basic condition of high pH (high conductivity). Taken together, this non-contact conductivity measurement for monitoring sample preparation will not only facilitate automation of the sample preparation and processing, but will also act as a way to optimize the operational time and use of consumables

  9. Direct proton conductance through the TRPV1 pore and multimerization of TRPV channel subunits

    OpenAIRE

    Hellwig, Nicole Barbara

    2010-01-01

    TRPV1-induced intracellular acidification: The vanilloid receptor-related transient receptor potential channels (TRPV) belong to the superfamily of hexahelical cation channels and are integral components of thermosensation, pain perception and Ca2+-reabsorption in kidney and intestine. The vanilloid receptor (TRPV1), a poorly selective cation channel, is expressed in dorsal root ganglion (DRG) neurons and is regulated by diverse stimuli including capsaicin, endovanilloids and heat. Since a...

  10. Thermal conductivity measurements in unsaturated hydrate-bearing sediments

    Science.gov (United States)

    Dai, Sheng; Cha, Jong-Ho; Rosenbaum, Eilis J.; Zhang, Wu; Seol, Yongkoo

    2015-08-01

    Current database on the thermal properties of hydrate-bearing sediments remains limited and has not been able to capture their consequential changes during gas production where vigorous phase changes occur in this unsaturated system. This study uses the transient plane source (TPS) technique to measure the thermal conductivity of methane hydrate-bearing sediments with various hydrate/water/gas saturations. We propose a simplified method to obtain thermal properties from single-sided TPS signatures. Results reveal that both volume fraction and distribution of the pore constituents govern the thermal conductivity of unsaturated specimens. Thermal conductivity hysteresis is observed due to water redistribution and fabric change caused by hydrate formation and dissociation. Measured thermal conductivity increases evidently when hydrate saturation Sh > 30-40%, shifting upward from the geometric mean model prediction to a Pythagorean mixing model. These observations envisage a significant drop in sediment thermal conductivity when residual hydrate/water saturation falls below ~40%, hindering further gas production.

  11. Thermal conductivity measurements at cryogenic temperatures at LASA

    International Nuclear Information System (INIS)

    Broggi, F.; Pedrini, D.; Rossi, L.

    1995-08-01

    Here the improvement realised to have better control of the reference junction temperature and measurements carried out on Nb 3 Sn cut out from 2 different coils (named LASA3 and LASA5), showing the difference between the longitudinal and the transverse thermal conductivity, is described. Two different methods of data analysis are presented, the DAM (derivative approximated method) and the TCI (thermal conductivity integral. The data analysis for the tungsten and the LASA5 coil has been done according to the two methods showing that the TCI method with polynomial functions is not adequate to describe the thermal conductivity. Only a polynomial fit based on the TCI method but limited at a lower order than the nominal, when the data are well distributed along the range of measurements, can describe reasonably the thermal conductivity dependence with the temperature. Finally the measurements on a rod of BSCCO 2212 high T c superconductor are presented

  12. Cryogenic Thermal Conductivity Measurements on Candidate Materials for Space Missions

    Science.gov (United States)

    Tuttle, JIm; Canavan, Ed; Jahromi, Amir

    2017-01-01

    Spacecraft and instruments on space missions are built using a wide variety of carefully-chosen materials. In addition to having mechanical properties appropriate for surviving the launch environment, these materials generally must have thermal conductivity values which meet specific requirements in their operating temperature ranges. Space missions commonly propose to include materials for which the thermal conductivity is not well known at cryogenic temperatures. We developed a test facility in 2004 at NASAs Goddard Space Flight Center to measure material thermal conductivity at temperatures between 4 and 300 Kelvin, and we have characterized many candidate materials since then. The measurement technique is not extremely complex, but proper care to details of the setup, data acquisition and data reduction is necessary for high precision and accuracy. We describe the thermal conductivity measurement process and present results for several materials.

  13. Gating mechanisms of mechanosensitive channels of large conductance, I: a continuum mechanics-based hierarchical framework.

    Science.gov (United States)

    Chen, Xi; Cui, Qiang; Tang, Yuye; Yoo, Jejoong; Yethiraj, Arun

    2008-07-01

    A hierarchical simulation framework that integrates information from molecular dynamics (MD) simulations into a continuum model is established to study the mechanical response of mechanosensitive channel of large-conductance (MscL) using the finite element method (FEM). The proposed MD-decorated FEM (MDeFEM) approach is used to explore the detailed gating mechanisms of the MscL in Escherichia coli embedded in a palmitoyloleoylphosphatidylethanolamine lipid bilayer. In Part I of this study, the framework of MDeFEM is established. The transmembrane and cytoplasmic helices are taken to be elastic rods, the loops are modeled as springs, and the lipid bilayer is approximated by a three-layer sheet. The mechanical properties of the continuum components, as well as their interactions, are derived from molecular simulations based on atomic force fields. In addition, analytical closed-form continuum model and elastic network model are established to complement the MDeFEM approach and to capture the most essential features of gating. In Part II of this study, the detailed gating mechanisms of E. coli-MscL under various types of loading are presented and compared with experiments, structural model, and all-atom simulations, as well as the analytical models established in Part I. It is envisioned that such a hierarchical multiscale framework will find great value in the study of a variety of biological processes involving complex mechanical deformations such as muscle contraction and mechanotransduction.

  14. In situ measurement of conductivity during nanocomposite film deposition

    International Nuclear Information System (INIS)

    Blattmann, Christoph O.; Pratsinis, Sotiris E.

    2016-01-01

    Highlights: • Flame-made nanosilver dynamics are elucidated in the gas-phase & on substrates. • The resistance of freshly depositing nanosilver layers is monitored. • Low T g polymers facilitate rapid synthesis of conductive films. • Conductive nanosilver films form on top of or within the polymer depending on MW. - Abstract: Flexible and electrically conductive nanocomposite films are essential for small, portable and even implantable electronic devices. Typically, such film synthesis and conductivity measurement are carried out sequentially. As a result, optimization of filler loading and size/morphology characteristics with respect to film conductivity is rather tedious and costly. Here, freshly-made Ag nanoparticles (nanosilver) are made by scalable flame aerosol technology and directly deposited onto polymeric (polystyrene and poly(methyl methacrylate)) films during which the resistance of the resulting nanocomposite is measured in situ. The formation and gas-phase growth of such flame-made nanosilver, just before incorporation onto the polymer film, is measured by thermophoretic sampling and microscopy. Monitoring the nanocomposite resistance in situ reveals the onset of conductive network formation by the deposited nanosilver growth and sinternecking. The in situ measurement is much faster and more accurate than conventional ex situ four-point resistance measurements since an electrically percolating network is detected upon its formation by the in situ technique. Nevertheless, general resistance trends with respect to filler loading and host polymer composition are consistent for both in situ and ex situ measurements. The time lag for the onset of a conductive network (i.e., percolation) depends linearly on the glass transition temperature (T g ) of the host polymer. This is attributed to the increased nanoparticle-polymer interaction with decreasing T g . Proper selection of the host polymer in combination with in situ resistance monitoring

  15. Measurement of turbulent flow in a narrow open channel

    Directory of Open Access Journals (Sweden)

    Sarkar Sankar

    2016-09-01

    Full Text Available The paper presents the experimental results of turbulent flow over hydraulically smooth and rough beds. Experiments were conducted in a rectangular flume under the aspect ratio b/h = 2 (b = width of the channel 0.5 m, and h = flow depth 0.25 m for both the bed conditions. For the hydraulically rough bed, the roughness was created by using 3/8″ commercially available angular crushed stone chips; whereas sand of a median diameter d50 = 1.9 mm was used as the bed material for hydraulically smooth bed. The three-dimensional velocity components were captured by using a Vectrino (an acoustic Doppler velocimeter. The study focuses mainly on the turbulent characteristics within the dip that were observed towards the sidewall (corner of the channel where the maximum velocity occurs below the free-surface. It was also observed that the nondimensional Reynolds shear stress changes its sign from positive to negative within the dip. The quadrant plots for the turbulent bursting shows that the signs of all the bursting events change within the dip. Below the dip, the probability of the occurrence of sweeps and ejections are more than that of inward and outward interactions. On the other hand, within the dip, the probability of the occurrence of the outward and inward interactions is more than that of sweeps and ejections.

  16. AC-Conductivity measurements on γ-aluminium oxynitride

    NARCIS (Netherlands)

    Willems, H.X.; Hal, van P.F.; Metselaar, R.; With, de G.

    1995-01-01

    AC-conductivity measurements were performed on aluminium oxynitrides (Alons) because of their interesting defect structure. Although it became apparent that these Alons are not stable in the temperature range used, the electrical properties of the materials could be measured with impedance

  17. Optical sensor for heat conduction measurement in biological tissue

    International Nuclear Information System (INIS)

    Gutierrez-Arroyo, A; Sanchez-Perez, C; Aleman-Garcia, N

    2013-01-01

    This paper presents the design of a heat flux sensor using an optical fiber system to measure heat conduction in biological tissues. This optoelectronic device is based on the photothermal beam deflection of a laser beam travelling in an acrylic slab this deflection is measured with a fiber optic angle sensor. We measure heat conduction in biological samples with high repeatability and sensitivity enough to detect differences in tissues from three chicken organs. This technique could provide important information of vital organ function as well as the detect modifications due to degenerative diseases or physical damage caused by medications or therapies.

  18. Measurements of local two-phase flow parameters in a boiling flow channel

    International Nuclear Information System (INIS)

    Yun, Byong Jo; Park, Goon-CherI; Chung, Moon Ki; Song, Chul Hwa

    1998-01-01

    Local two-phase flow parameters were measured lo investigate the internal flow structures of steam-water boiling flow in an annulus channel. Two kinds of measuring methods for local two-phase flow parameters were investigated. These are a two-conductivity probe for local vapor parameters and a Pitot cube for local liquid parameters. Using these probes, the local distribution of phasic velocities, interfacial area concentration (IAC) and void fraction is measured. In this study, the maximum local void fraction in subcooled boiling condition is observed around the heating rod and the local void fraction is smoothly decreased from the surface of a heating rod to the channel center without any wall void peaking, which was observed in air-water experiments. The distributions of local IAC and bubble frequency coincide with those of local void fraction for a given area-averaged void fraction. (author)

  19. Modulation of the conductance of a 2,2′-bipyridine-functionalized peptidic ion channel by Ni2+

    Science.gov (United States)

    Pilz, Claudia S.

    2008-01-01

    An α-helical amphipathic peptide with the sequence H2N-(LSSLLSL)3-CONH2 was obtained by solid phase synthesis and a 2,2′-bipyridine was coupled to its N-terminus, which allows complexation of Ni2+. Complexation of the 2,2′-bipyridine residues was proven by UV/Vis spectroscopy. The peptide helices were inserted into lipid bilayers (nano black lipid membranes, nano-BLMs) that suspend the pores of porous alumina substrates with a pore diameter of 60 nm by applying a potential difference. From single channel recordings, we were able to distinguish four distinct conductance states, which we attribute to an increasing number of peptide helices participating in the conducting helix bundle. Addition of Ni2+ in micromolar concentrations altered the conductance behaviour of the formed ion channels in nano-BLMs considerably. The first two conductance states appear much more prominent demonstrating that the complexation of bipyridine by Ni2+ results in a considerable confinement of the observed multiple conductance states. However, the conductance levels were independent of the presence of Ni2+. Moreover, from a detailed analysis of the open lifetimes of the channels, we conclude that the complexation of Ni2+ diminishes the frequency of channel events with larger open times. Electronic supplementary material The online version of this article (doi:10.1007/s00249-008-0298-8) contains supplementary material, which is available to authorized users. PMID:18347789

  20. Simultaneous Rheoelectric Measurements of Strongly Conductive Complex Fluids

    Science.gov (United States)

    Helal, Ahmed; Divoux, Thibaut; McKinley, Gareth H.

    2016-12-01

    We introduce an modular fixture designed for stress-controlled rheometers to perform simultaneous rheological and electrical measurements on strongly conductive complex fluids under shear. By means of a nontoxic liquid metal at room temperature, the electrical connection to the rotating shaft is completed with minimal additional mechanical friction, allowing for simultaneous stress measurements at values as low as 1 Pa. Motivated by applications such as flow batteries, we use the capabilities of this design to perform an extensive set of rheoelectric experiments on gels formulated from attractive carbon-black particles, at concentrations ranging from 4 to 15 wt %. First, experiments on gels at rest prepared with different shear histories show a robust power-law scaling between the elastic modulus G0' and the conductivity σ0 of the gels—i.e., G0'˜σ0α, with α =1.65 ±0.04 , regardless of the gel concentration. Second, we report conductivity measurements performed simultaneously with creep experiments. Changes in conductivity in the early stage of the experiments, also known as the Andrade-creep regime, reveal for the first time that plastic events take place in the bulk, while the shear rate γ ˙ decreases as a weak power law of time. The subsequent evolution of the conductivity and the shear rate allows us to propose a local yielding scenario that is in agreement with previous velocimetry measurements. Finally, to establish a set of benchmark data, we determine the constitutive rheological and electrical behavior of carbon-black gels. Corrections first introduced for mechanical measurements regarding shear inhomogeneity and wall slip are carefully extended to electrical measurements to accurately distinguish between bulk and surface contributions to the conductivity. As an illustrative example, we examine the constitutive rheoelectric properties of five different grades of carbon-black gels and we demonstrate the relevance of this rheoelectric apparatus as a

  1. Method for Measuring Thermal Conductivity of Small Samples Having Very Low Thermal Conductivity

    Science.gov (United States)

    Miller, Robert A.; Kuczmarski, Maria a.

    2009-01-01

    This paper describes the development of a hot plate method capable of using air as a standard reference material for the steady-state measurement of the thermal conductivity of very small test samples having thermal conductivity on the order of air. As with other approaches, care is taken to ensure that the heat flow through the test sample is essentially one-dimensional. However, unlike other approaches, no attempt is made to use heated guards to block the flow of heat from the hot plate to the surroundings. It is argued that since large correction factors must be applied to account for guard imperfections when sample dimensions are small, it may be preferable to simply measure and correct for the heat that flows from the heater disc to directions other than into the sample. Experimental measurements taken in a prototype apparatus, combined with extensive computational modeling of the heat transfer in the apparatus, show that sufficiently accurate measurements can be obtained to allow determination of the thermal conductivity of low thermal conductivity materials. Suggestions are made for further improvements in the method based on results from regression analyses of the generated data.

  2. Channel Storage change: a new remote sensed surface water measurement

    Science.gov (United States)

    Coss, S. P.; Durand, M. T.; Yi, Y.; Guo, Q.; Shum, C. K.; Allen, G. H.; Pavelsky, T.

    2017-12-01

    Here we present river channel storage change (CSC) measurements for 17 major world rivers from 2002-2016. We combined interpolated daily 1 km resolution Global River Radar Altimeter Time Series (GRRATS) river surface elevation data with static widths from the global river Global River Widths from Landsat (GRWL) dataset, to generate preliminary channel storage measurements. CSC is a previously unmeasured component of the terrestrial water balance It is a fundamental Earth science quantity with global bearing on floodplains, ecology, and geochemistry. CSC calculations require only remote sensed data, making them an ideal tool for studying remote regions where hydrological data is not easily accessible. CSC is uniquely suited to determine the role of hydrologic and hydraulic controls in basins with strong seasonal cycles (freeze-up and break-up). The cumulative CSC anomaly can impart spatial details that discharge measurements cannot. With this new measurement, we may be able to determine critical hydrological and hydraulic controls on rapidly changing systems like Arctic rivers. Results for Mississippi River indicate that peak CSC anomaly was the highest in 2011 (12.6 km3) and minimum CSC anomaly was in 2012 (-12.2 km3). Peak CSC has most frequently occurs in May (5 years), but has come as late in the year as July, and as early as January. Results for the Yukon River indicate that peak CSC anomaly was the highest in 2013 (13.9 km3) and minimum CSC anomaly was in 2010 (-14.2 km3). Peak CSC has most frequently come in early to mid-June (4-18), but has occurred in May (19-31) four years in the study period (three of the last 6 years) and once on April 30th.

  3. Wet method for measuring starch gelatinization temperature using electrical conductivity.

    Science.gov (United States)

    Morales-Sanchez, E; Figueroa, J D C; Gaytan-Martínez, M

    2009-09-01

    The objective of the present study was to develop a method for obtaining the gelatinization temperature of starches by using electrical conductivity. Native starches from corn, rice, potato, and wheat were prepared with different proportions of water and heated from room temperature to 90 degrees C, in a device especially designed for monitoring the electrical conductivity as a function of temperature. The results showed a linear trend of the electrical conductivity with the temperature until it reaches the onset gelatinization temperature. After that point, the electrical conductivity presented an increment or decrement depending on the water content in the sample and it was related to starch swelling and gelatinization phenomena. At the end gelatinization temperature, the conductivity becomes stable and linear, indicating that there are no more changes of phase. The starch gelatinization parameter, which was evaluated in the 4 types of starches using the electrical conductivity, was compared with those obtained by using differential scanning calorimeter (DSC). The onset temperature at which the electrical conductivity increased or decreased was found to be similar to that obtained by DSC. Also, the final temperature at which the electrical conductivity returned to linearity matched the end gelatinization temperature of the DSC. Further, a wet method for measuring the onset, peak, and end gelatinization temperatures as a function of temperature using the electrical conductivity curves is presented for a starch-water suspension.

  4. Electrical conductivity measurements in shock compressed liquid nitrogen

    International Nuclear Information System (INIS)

    Hamilton, D.C.; Mitchell, A.C.; Nellis, W.J.

    1985-06-01

    The electrical conductivity of shock compressed liquid nitrogen was measured in the pressure range 20 to 50 GPa using a two-stage light-gas gun. The conductivities covered a range 4 x 10 -2 to 1 x 10 2 ohm -1 cm -1 . The data are discussed in terms of a liquid semiconductor model below the onset of the dissociative phase transition at 30 GPa. 15 refs., 1 fig

  5. In situ measurement of ceramic vacuum chamber conductive coating quality

    International Nuclear Information System (INIS)

    Doose, C.; Harkay, K.; Kim, S.; Milton, S.

    1997-01-01

    A method for measuring the relative surface resistivity and quality of conductive coatings on ceramic vacuum chambers was developed. This method is unique in that it allows one to test the coating even after the ceramic chamber is installed in the accelerator and under vacuum; furthermore, the measurement provides a localized surface reading of the coating conductance. The method uses a magnetic probe is calibrated using the measured DC end-to-end resistance of the tube under test and by comparison to a high quality test surface. The measurement method has also been verified by comparison to high frequency impedance measurements. A detailed description, results, and sensitivity of the technique are given here

  6. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    Science.gov (United States)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  7. Caliper variable sonde for thermal conductivity measurements in situ

    Energy Technology Data Exchange (ETDEWEB)

    Oelsner, C; Leischner, H; Pischel, S

    1968-01-01

    For the measurement of the thermal conductivity of the formations surrounding a borehole, a sonde having variable diameter (consisting of an inflatable rubber cylinder with heating wires embedded in its wall) is described. The conditions for the usual sonde made of metal are no longer fulfilled, but the solution to the problem of determining the thermal conductivity from the temperature rise is given, based on an approach by Carslaw and Jaeger, which contains the Bessel functions of the second kind. It is shown that a simpler solution for large values of time can be obtained through the Laplace transformation, and the necessary series developments for computer application are also given. The sonde and the necessary measuring circuitry are described. Tests measurements have indicated that the thermal conductivity can be determined with this sonde with a precision of + 10%.

  8. Apparatus for simultaneously measuring electrical conductivity and oxygen fugacity

    Energy Technology Data Exchange (ETDEWEB)

    Netherton, R.; Duba, A.

    1978-01-31

    Electrical conductivity studies of silicates are useful in determining temperature vs depth in the earth. Realistic laboratory measurements of conduction mechanisms require that exact determinations of oxygen fugacity (fo{sub 2}) be made in the experimental environment. An apparatus is described that monitors system fo{sub 2} with a calcia-doped zirconia-oxygen cell while measuring electrical conductivity of iron-bearing silicates at high temperature (greater than 1000 K). The fo{sub 2} calculated thermodynamically from CO/CO{sub 2} mixing ratios agreed well with measurements made with the zirconia cell at 1473 K, except for fo{sub 2} greater than 10{sup -4} Pa, where, on a log{sub 10} scale, mixing-ratio errors were as large as +- 0.2. These errors are attributed to oxygen contamination in the CO{sub 2} and to mobile carbon deposits that formed in the apparatus.

  9. In-situ measurements of soil-water conductivity

    International Nuclear Information System (INIS)

    Murphy, C.E.

    1978-01-01

    Radionuclides and other environmentally important materials often move in association with water. In terrestrial ecosystems, the storage and movement of water in the soil is of prime importance to the hydrologic cycle of the ecosystem. The soil-water conductivity (the rate at which water moves through the soil) is a necessary input to models of soil-water movement. In situ techniques for measurement of soil-water conductivity have the advantage of averaging soil-water properties over larger areas than most laboratory methods. The in situ techniques also cause minimum disturbance of the soil under investigation. Results of measurements using a period of soil-water drainage after initial wetting indicate that soil-water conductivity and its variation with soil-water content can be determined with reasonable accuracy for the plot where the measurements were made. Further investigations are being carried out to look at variability between plots within a soil type

  10. Simultaneous measurements of thermal conductivity and electrical conductivity of micro-machined Silicon films

    International Nuclear Information System (INIS)

    Hagino, H; Kawahara, Y; Goto, A; Miyazaki, K

    2012-01-01

    The in-plane effective thermal conductivity of free-standing Si thin films with periodic micropores was measured at -100 to 0 °C. The Si thin films with micropores were prepared from silicon-on-insulator (SOI) wafers by standard microfabrication processes. The dimensions of the free-standing Si thin films were 200μm×150μm×2 μm, with staggered 4 μm pores having an average pitch of 4 mm. The Si thin film serves both as a heater and thermometer. The average temperature rise of the thin film is a function of its in-plane thermal conductivity. The effective thermal conductivity was calculated using a simple one-dimensional heat conduction model. The measured thermal conductivity was much lower than that expected based on classical model evaluations. A significant phonon size effect was observed even in the microsized structures, and the mean free path for phonons is very long even at the room temperature.

  11. Functional Architecture of the Cytoplasmic Entrance to the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel Pore.

    Science.gov (United States)

    El Hiani, Yassine; Linsdell, Paul

    2015-06-19

    As an ion channel, the cystic fibrosis transmembrane conductance regulator must form a continuous pathway for the movement of Cl(-) and other anions between the cytoplasm and the extracellular solution. Both the structure and the function of the membrane-spanning part of this pathway are well defined. In contrast, the structure of the pathway that connects the cytoplasm to the membrane-spanning regions is unknown, and functional roles for different parts of the protein forming this pathway have not been described. We used patch clamp recording and substituted cysteine accessibility mutagenesis to identify positively charged amino acid side chains that attract cytoplasmic Cl(-) ions to the inner mouth of the pore. Our results indicate that the side chains of Lys-190, Arg-248, Arg-303, Lys-370, Lys-1041, and Arg-1048, located in different intracellular loops of the protein, play important roles in the electrostatic attraction of Cl(-) ions. Mutation and covalent modification of these residues have charge-dependent effects on the rate of Cl(-) permeation, demonstrating their functional role in maximization of Cl(-) flux. Other nearby positively charged side chains were not involved in electrostatic interactions with Cl(-). The location of these Cl(-)-attractive residues suggests that cytoplasmic Cl(-) ions enter the pore via a lateral portal located between the cytoplasmic extensions to the fourth and sixth transmembrane helices; a secondary, functionally less relevant portal might exist between the extensions to the 10th and 12th transmembrane helices. These results define the cytoplasmic mouth of the pore and show how it attracts Cl(-) ions from the cytoplasm. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Nanostructuring of conduction channels in (In,Ga)As-InP heterostructures: Overcoming carrier generation caused by Ar ion milling

    Science.gov (United States)

    Hortelano, V.; Weidlich, H.; Semtsiv, M. P.; Masselink, W. T.; Ramsteiner, M.; Jahn, U.; Biermann, K.; Takagaki, Y.

    2018-04-01

    Nanometer-sized channels are fabricated in (In,Ga)As-InP heterostructures using Ar ion milling. The ion milling causes spontaneous creation of nanowires, and moreover, electrical conduction of the surface as carriers is generated by sputtering-induced defects. We demonstrate a method to restore electrical isolation in the etched area that is compatible with the presence of the nanochannels. We remove the heavily damaged surface layer using a diluted HCl solution and subsequently recover the crystalline order in the moderately damaged part by annealing. We optimize the HCl concentration to make the removal stop on its own before reaching the conduction channel part. The lateral depletion in the channels is shown to be almost absent.

  13. Thermal Conductivity Measurement and Analysis of Fully Ceramic Microencapsulated fuel

    International Nuclear Information System (INIS)

    Lee, H. G.; Kim, D. J.; Park, J. Y.; Kim, W. J.; Lee, S. J.

    2015-01-01

    FCM nuclear fuel is composed of tristructural isotropic(TRISO) fuel particle and SiC ceramic matrix. SiC ceramic matrix play an essential part in protecting fission product. In the FCM fuel concept, fission product is doubly protected by TRISO coating layer and SiC ceramic matrix in comparison with the current commercial UO2 fuel system of LWR. In addition to a safety enhancement of FCM fuel, thermal conductivity of SiC ceramic matrix is better than that of UO2 fuel. Because the centerline temperature of FCM fuel is lower than that of the current UO2 fuel due to the difference of thermal conductivity of fuel, an operational release of fission products from the fuel can be reduced. SiC ceramic has attracted for nuclear fuel application due to its high thermal conductivity properties with good radiation tolerant properties, a low neutron absorption cross-section and a high corrosion resistance. Thermal conductivity of ceramic matrix composite depends on the thermal conductivity of each component and the morphology of reinforcement materials such as fibers and particles. There are many results about thermal conductivity of fiber-reinforced composite like as SiCf/SiC composite. Thermal conductivity of SiC ceramics and FCM pellets with the volume fraction of TRISO particles were measured and analyzed by analytical models. Polycrystalline SiC ceramics and FCM pellets with TRISO particles were fabricated by hot press sintering with sintering additives. Thermal conductivity of the FCM pellets with TRISO particles of 0 vol.%, 10 vol.%, 20 vol.%, 30 vol.% and 40 vol.% show 68.4, 52.3, 46.8, 43.0 and 34.5 W/mK, respectively. As the volume fraction of TRISO particles increased, the measured thermal conductivity values closely followed the prediction of Maxwell's equation

  14. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Arindam Pal

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for 2×2 MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  15. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Pal Arindam

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  16. Apparent intermediate K conductance channel hyposmotic activation in human lens epithelial cells.

    Science.gov (United States)

    Lauf, Peter K; Misri, Sandeep; Chimote, Ameet A; Adragna, Norma C

    2008-03-01

    This study explores the nature of K fluxes in human lens epithelial cells (LECs) in hyposmotic solutions. Total ion fluxes, Na-K pump, Cl-dependent Na-K-2Cl (NKCC), K-Cl (KCC) cotransport, and K channels were determined by 85Rb uptake and cell K (Kc) by atomic absorption spectrophotometry, and cell water gravimetrically after exposure to ouabain +/- bumetanide (Na-K pump and NKCC inhibitors), and ion channel inhibitors in varying osmolalities with Na, K, or methyl-d-glucamine and Cl, sulfamate, or nitrate. Reverse transcriptase polymerase chain reaction (RT-PCR), Western blot analyses, and immunochemistry were also performed. In isosmotic (300 mosM) media approximately 90% of the total Rb influx occurred through the Na-K pump and NKCC and approximately 10% through KCC and a residual leak. Hyposmotic media (150 mosM) decreased K(c) by a 16-fold higher K permeability and cell water, but failed to inactivate NKCC and activate KCC. Sucrose replacement or extracellular K to >57 mM, but not Rb or Cs, in hyposmotic media prevented Kc and water loss. Rb influx equaled Kc loss, both blocked by clotrimazole (IC50 approximately 25 microM) and partially by 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34) inhibitors of the IK channel KCa3.1 but not by other K channel or connexin hemichannel blockers. Of several anion channel blockers (dihydro-indenyl)oxy]alkanoic acid (DIOA), 4-2(butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)oxybutyric acid (DCPIB), and phloretin totally or partially inhibited Kc loss and Rb influx, respectively. RT-PCR and immunochemistry confirmed the presence of KCa3.1 channels, aside of the KCC1, KCC2, KCC3 and KCC4 isoforms. Apparently, IK channels, possibly in parallel with volume-sensitive outwardly rectifying Cl channels, effect regulatory volume decrease in LECs.

  17. Channel Measurement and Modeling for 5G Urban Microcellular Scenarios

    Directory of Open Access Journals (Sweden)

    Michael Peter

    2016-08-01

    Full Text Available In order to support the development of channel models for higher frequency bands, multiple urban microcellular measurement campaigns have been carried out in Berlin, Germany, at 60 and 10 GHz. In this paper, the collected data is uniformly analyzed with focus on the path loss (PL and the delay spread (DS. It reveals that the ground reflection has a dominant impact on the fading behavior. For line-of-sight conditions, the PL exponents are close to free space propagation at 60 GHz, but slightly smaller (1.62 for the street canyon at 10 GHz. The DS shows a clear dependence on the scenario (median values between 16 and 38 ns and a strong distance dependence for the open square and the wide street canyon. The dependence is less distinct for the narrow street canyon with residential buildings. This behavior is consistent with complementary ray tracing simulations, though the simplified model tends to overestimate the DS.

  18. Algorithms for diagnostics of the measuring channels and technological equipment at NPP with WWER-1000

    International Nuclear Information System (INIS)

    Vysotskij, V.G.

    1997-01-01

    An algorithm for diagnostics of the state of measuring channels of an information computer system with usage of analysis of statistical channel characteristics is presented. An algorithm for testing the generalized state of the NPP technological equipment is proposed

  19. The molecular mechanism of multi-ion conduction in K{sup +} channels

    Energy Technology Data Exchange (ETDEWEB)

    Gwan, J.F.

    2007-01-19

    Steered molecular dynamics (SMD) simulation method is applied to a fully solvated membrane-channel model for studying the ion permeation process in potassium channels. The channel model is based on the crystallographic structure of a prokaryotic K{sup +} channel- the KcsA channel, which is a representative of most known eukaryotic K{sup +} channels. It has long been proposed that the ion transportation in a conventional K{sup +}-channel follows a multi-ion fashion: permeating ions line in a queue in the channel pore and move in a single file through the channel. The conventional view of multi-ion transportation is that the electrostatic repulsion between ions helps to overcome the attraction between ions and the channel pore. In this study, we proposed two SMD simulation schemes, referred to 'the single-ion SMD' simulations and 'the multi-ion SMD' simulations. Concerted movements of a K-W-K sequence in the selectivity filter were observed in the single-ion SMD simulations. The analysis of the concerted movement reveals the molecular mechanism of the multi-ion transportation. It shows that, rather than the long range electrostatic interaction, the short range polar interaction is a more dominant factor in the multi-ion transportation. The polar groups which play a role in the concerted transportation are the water molecules and the backbone carbonyl groups of the selectivity filter. The polar interaction is sensitive to the relative orientation of the polar groups. By changing the orientation of a polar group, the interaction may switch from attractive to repulsive or vice versa. By this means, the energy barrier between binding sites in the selectivity filter can be switched on and off, and therefore the K{sup +} may be able to move to the neighboring binding site without an external driving force. The concerted transportation in the selectivity filter requires a delicate cooperation between K{sup +}, waters, and the backbone carbonyl groups. To

  20. Measuring kinetics of complex single ion channel data using mean-variance histograms.

    Science.gov (United States)

    Patlak, J B

    1993-07-01

    The measurement of single ion channel kinetics is difficult when those channels exhibit subconductance events. When the kinetics are fast, and when the current magnitudes are small, as is the case for Na+, Ca2+, and some K+ channels, these difficulties can lead to serious errors in the estimation of channel kinetics. I present here a method, based on the construction and analysis of mean-variance histograms, that can overcome these problems. A mean-variance histogram is constructed by calculating the mean current and the current variance within a brief "window" (a set of N consecutive data samples) superimposed on the digitized raw channel data. Systematic movement of this window over the data produces large numbers of mean-variance pairs which can be assembled into a two-dimensional histogram. Defined current levels (open, closed, or sublevel) appear in such plots as low variance regions. The total number of events in such low variance regions is estimated by curve fitting and plotted as a function of window width. This function decreases with the same time constants as the original dwell time probability distribution for each of the regions. The method can therefore be used: 1) to present a qualitative summary of the single channel data from which the signal-to-noise ratio, open channel noise, steadiness of the baseline, and number of conductance levels can be quickly determined; 2) to quantify the dwell time distribution in each of the levels exhibited. In this paper I present the analysis of a Na+ channel recording that had a number of complexities. The signal-to-noise ratio was only about 8 for the main open state, open channel noise, and fast flickers to other states were present, as were a substantial number of subconductance states. "Standard" half-amplitude threshold analysis of these data produce open and closed time histograms that were well fitted by the sum of two exponentials, but with apparently erroneous time constants, whereas the mean

  1. Mono-Heteromeric Configurations of Gap Junction Channels Formed by Connexin43 and Connexin45 Reduce Unitary Conductance and Determine both Voltage Gating and Metabolic Flux Asymmetry

    Directory of Open Access Journals (Sweden)

    Guoqiang Zhong

    2017-05-01

    Full Text Available In cardiac tissues, the expression of multiple connexins (Cx40, Cx43, Cx45, and Cx30.2 is a requirement for proper development and function. Gap junctions formed by these connexins have distinct permeability and gating mechanisms. Since a single cell can express more than one connexin isoform, the formation of hetero-multimeric gap junction channels provides a tissue with an enormous repertoire of combinations to modulate intercellular communication. To study further the perm-selectivity and gating properties of channels containing Cx43 and Cx45, we studied two monoheteromeric combinations in which a HeLa cell co-transfected with Cx43 and Cx45 was paired with a cell expressing only one of these connexins. Macroscopic measurements of total conductance between cell pairs indicated a drastic reduction in total conductance for mono-heteromeric channels. In terms of Vj dependent gating, Cx43 homomeric connexons facing heteromeric connexons only responded weakly to voltage negativity. Cx45 homomeric connexons exhibited no change in Vj gating when facing heteromeric connexons. The distributions of unitary conductances (γj for both mono-heteromeric channels were smaller than predicted, and both showed low permeability to the fluorescent dyes Lucifer yellow and Rhodamine123. For both mono-heteromeric channels, we observed flux asymmetry regardless of dye charge: flux was higher in the direction of the heteromeric connexon for MhetCx45 and in the direction of the homomeric Cx43 connexon for MhetCx43. Thus, our data suggest that co-expression of Cx45 and Cx43 induces the formation of heteromeric connexons with greatly reduced permeability and unitary conductance. Furthermore, it increases the asymmetry for voltage gating for opposing connexons, and it favors asymmetric flux of molecules across the junction that depends primarily on the size (not the charge of the crossing molecules.

  2. Mono-Heteromeric Configurations of Gap Junction Channels Formed by Connexin43 and Connexin45 Reduce Unitary Conductance and Determine both Voltage Gating and Metabolic Flux Asymmetry

    Science.gov (United States)

    Zhong, Guoqiang; Akoum, Nazem; Appadurai, Daniel A.; Hayrapetyan, Volodya; Ahmed, Osman; Martinez, Agustin D.; Beyer, Eric C.; Moreno, Alonso P.

    2017-01-01

    In cardiac tissues, the expression of multiple connexins (Cx40, Cx43, Cx45, and Cx30.2) is a requirement for proper development and function. Gap junctions formed by these connexins have distinct permeability and gating mechanisms. Since a single cell can express more than one connexin isoform, the formation of hetero-multimeric gap junction channels provides a tissue with an enormous repertoire of combinations to modulate intercellular communication. To study further the perm-selectivity and gating properties of channels containing Cx43 and Cx45, we studied two monoheteromeric combinations in which a HeLa cell co-transfected with Cx43 and Cx45 was paired with a cell expressing only one of these connexins. Macroscopic measurements of total conductance between cell pairs indicated a drastic reduction in total conductance for mono-heteromeric channels. In terms of Vj dependent gating, Cx43 homomeric connexons facing heteromeric connexons only responded weakly to voltage negativity. Cx45 homomeric connexons exhibited no change in Vj gating when facing heteromeric connexons. The distributions of unitary conductances (γj) for both mono-heteromeric channels were smaller than predicted, and both showed low permeability to the fluorescent dyes Lucifer yellow and Rhodamine123. For both mono-heteromeric channels, we observed flux asymmetry regardless of dye charge: flux was higher in the direction of the heteromeric connexon for MhetCx45 and in the direction of the homomeric Cx43 connexon for MhetCx43. Thus, our data suggest that co-expression of Cx45 and Cx43 induces the formation of heteromeric connexons with greatly reduced permeability and unitary conductance. Furthermore, it increases the asymmetry for voltage gating for opposing connexons, and it favors asymmetric flux of molecules across the junction that depends primarily on the size (not the charge) of the crossing molecules. PMID:28611680

  3. Broadband Mm-Wave OFDM Communications in Doubly Selective Channel: Performance Evaluation Using Measured Mm-Wave Channel

    DEFF Research Database (Denmark)

    Chen, Xiaoming; Fan, Wei; Pedersen, Gert F.

    2018-01-01

    In this work, we evaluate the performance of the broadband millimeter-wave (mm-wave) OFDM system in the presence of phase noise (PN) of phase-locked loop based oscillator and delay spread of measured mm-wave channel. It is shown, using Akaike's information criterion, that the channel tap...... coefficients of the broadband mm-wave channel do not follow Gaussian distribution due to the broad bandwidth. It is also shown that, given a cyclic prefix (CP) length for a certain delay spread, an effective PN mitigation scheme enables a PN corrupted OFDM system to function with small subcarrier spacing and...

  4. Directional rf probe for measurement of conductivity of flowing plasmas

    International Nuclear Information System (INIS)

    Jayakumar, R.; Chakravarthy, D.P.; Rohatgi, V.K.

    1977-01-01

    An electrodeless immersible rf probe for measurement of plasma conductivity in the range 0.01 to 100 mho/m has been designed and fabricated. The probe, with an overall diameter of 11 mm, employs unidirectional electromagnetic field lines which reduce the inaccuracies caused by insertion of the probe in a flowing plasma. In the range studied the probe output shows a linear relationship with the conductivity of the medium. Such probes are of interest in the study of MHD and reentry plasmas

  5. Assembly for electrical conductivity measurements in the piston cylinder device

    Science.gov (United States)

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  6. Thermal conductivity of mesoporous films measured by Raman spectroscopy

    Science.gov (United States)

    Stoib, B.; Filser, S.; Petermann, N.; Wiggers, H.; Stutzmann, M.; Brandt, M. S.

    2014-04-01

    We measure the in-plane thermal conductance of mesoporous Ge and SiGe thin films using the Raman-shift method and, based on a finite differences simulation accounting for the geometry of the sample, extract the in-plane thermal conductivity. For a suspended thin film of laser-sintered SiGe nanoparticles doped with phosphorus, we find an effective in-plane thermal conductivity of 0.05 W/m K in vacuum for a temperature difference of 400 K and a mean temperature of 500 K. Under similar conditions, the effective in-plane thermal conductivity of a laser-sintered undoped Ge nanoparticle film is 0.5 W/m K. Accounting for a porosity of approximately 50%, the normalized thermal conductivities are 0.1 W/m K and 1 W/m K, respectively. The thermoelectric performance is discussed, considering that the electrical in-plane conductivity is also affected by the mesoporosity.

  7. System to Measure Thermal Conductivity and Seebeck Coefficient for Thermoelectrics

    Science.gov (United States)

    Kim, Hyun-Jung; Skuza, Jonathan R.; Park, Yeonjoon; King, Glen C.; Choi, Sang H.; Nagavalli, Anita

    2012-01-01

    The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential property measurement for evaluating the potential performance of novel thermoelectric materials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at elevated temperatures. This has led to the implementation of nonstandardized practices that have further complicated the confirmation of reported high ZT materials. The major objective of the procedure described is for the simultaneous measurement of the Seebeck coefficient and thermal diffusivity within a given temperature range. These thermoelectric measurements must be precise, accurate, and reproducible to ensure meaningful interlaboratory comparison of data. The custom-built thermal characterization system described in this NASA-TM is specifically designed to measure the inplane thermal diffusivity, and the Seebeck coefficient for materials in the ranging from 73 K through 373 K.

  8. Characterizing the performance of an affordable, multichannel conductivity probe for density measurements in stratified flows

    Science.gov (United States)

    Subramanian, Balaji; Carminati, Marco; Luzzatto-Fegiz, Paolo

    2017-11-01

    In stratified flows, conductivity (combined with temperature) is often used to measure density. The conductivity probes typically used can resolve very fine spatial scales, but on the downside they are fragile, expensive, sensitive to environmental noise and have only single channel capability. Recently a low-cost, robust, arduino-based probe called Conduino was developed, which can be valuable in a wide range of applications where resolving extremely small spatial scales is not needed. This probe uses micro-USB connectors as actual conductivity sensors with a custom designed electronic board for simultaneous acquisition from multiple probes, with conductivity resolution comparable to commercially available PME conductivity probe. A detailed assessment of performance of this Conduino probe is described here. To establish time response and sensitivity as a function of electrode geometry, we build a variety of shapes for different kinds of applications, with tip spacing ranging from 0.5-2.5 mm, and with electrode length ranging from 2.3-6 mm. We set up a two-layer density profile and traverse it rapidly, yielding a time response comparable to PME. The Conduino's multi-channel capability is used to operate probe arrays, which helps to construct density fields in stratified flows.

  9. Thermal conductivity and emissivity measurements of uranium carbides

    International Nuclear Information System (INIS)

    Corradetti, S.; Manzolaro, M.; Andrighetto, A.; Zanonato, P.; Tusseau-Nenez, S.

    2015-01-01

    Highlights: • Thermal conductivity and emissivity measurements of uranium carbides were performed. • The tested materials are candidates as targets for radioactive ion beam production. • The results are correlated with the materials composition and microstructure. - Abstract: Thermal conductivity and emissivity measurements on different types of uranium carbide are presented, in the context of the ActiLab Work Package in ENSAR, a project within the 7th Framework Program of the European Commission. Two specific techniques were used to carry out the measurements, both taking place in a laboratory dedicated to the research and development of materials for the SPES (Selective Production of Exotic Species) target. In the case of thermal conductivity, estimation of the dependence of this property on temperature was obtained using the inverse parameter estimation method, taking as a reference temperature and emissivity measurements. Emissivity at different temperatures was obtained for several types of uranium carbide using a dual frequency infrared pyrometer. Differences between the analyzed materials are discussed according to their compositional and microstructural properties. The obtainment of this type of information can help to carefully design materials to be capable of working under extreme conditions in next-generation ISOL (Isotope Separation On-Line) facilities for the generation of radioactive ion beams.

  10. Quantitative shearography: error reduction by using more than three measurement channels

    International Nuclear Information System (INIS)

    Charrett, Tom O. H.; Francis, Daniel; Tatam, Ralph P.

    2011-01-01

    Shearography is a noncontact optical technique used to measure surface displacement derivatives. Full surface strain characterization can be achieved using shearography configurations employing at least three measurement channels. Each measurement channel is sensitive to a single displacement gradient component defined by its sensitivity vector. A matrix transformation is then required to convert the measured components to the orthogonal displacement gradients required for quantitative strain measurement. This transformation, conventionally performed using three measurement channels, amplifies any errors present in the measurement. This paper investigates the use of additional measurement channels using the results of a computer model and an experimental shearography system. Results are presented showing that the addition of a fourth channel can reduce the errors in the computed orthogonal components by up to 33% and that, by using 10 channels, reductions of around 45% should be possible.

  11. Capacitance measurements and AC conductivity of Nickel Phthalocyanine films

    International Nuclear Information System (INIS)

    Darwish, S.

    2005-01-01

    A C dark Current measurements of nickel phthalocyanine thin films using ohmic gold electrodes are investigated in the frequency range 30-10 Hz and within the temperature range 295-385 K. The A C conductivity as D Ac is found to vary as within the index s < 1, indicating a dominant hopping process at low temperatures. From the temperature dependence of A C conductivity, free carrier conduction with mean activation energy of 0.31 eV is observed at higher temperatures. Capacitance and loss tangent are found to be decreased with increasing frequency and increase with increasing temperature. Such characteristics are found to be in good qualitative agreement with existing equivalent circuit model assuming ohmic contacts

  12. Thermal conductivity and PVT measurements of pentafluoroethane (refrigerant HFC-125)

    International Nuclear Information System (INIS)

    Tsvetkov, O.B.; Kletski, A.V.; Laptev, Yu.A.

    1995-01-01

    By means of the transient and steady-state coaxial cylinder methods, the thermal conductivity of pentfluoroethane was investigated at temperatures from 187 to 419 K and pressures from atmospheric to 6.0 MPa. The estimated uncertainty of the measured results is ± (2-3)%. The operation of the experimental apparatus was validated by measuring the thermal conductivity of R22 and R12. Determinations of the vapor pressure and PVT properties were carried out by a constant-volume apparatus for the temperature range 263 to 443 K, pressures up to 6 MPa, and densities from 36 to 516 kg m -3 . The uncertainties in temperature, pressure, and density are less than ±10 mK, ±0.08%, and ±0.1%, respectively

  13. Detecting Electron Transport of Amino Acids by Using Conductance Measurement

    Directory of Open Access Journals (Sweden)

    Wei-Qiong Li

    2017-04-01

    Full Text Available The single molecular conductance of amino acids was measured by a scanning tunneling microscope (STM break junction. Conductance measurement of alanine gives out two conductance values at 10−1.85 G0 (1095 nS and 10−3.7 G0 (15.5 nS, while similar conductance values are also observed for aspartic acid and glutamic acid, which have one more carboxylic acid group compared with alanine. This may show that the backbone of NH2–C–COOH is the primary means of electron transport in the molecular junction of aspartic acid and glutamic acid. However, NH2–C–COOH is not the primary means of electron transport in the methionine junction, which may be caused by the strong interaction of the Au–SMe (methyl sulfide bond for the methionine junction. The current work reveals the important role of the anchoring group in the electron transport in different amino acids junctions.

  14. Measurements and Modeling of Conducted EMI in a Buck Chopper

    International Nuclear Information System (INIS)

    Fakhfakh, L.; Abid, S.; Ammous, A.

    2011-01-01

    The high increase of power electronic devices use (speed control, lighting, heating, automotive, etc...) requires the electrical, thermal and electromagnetic behavior studies. In this paper we developed a model to predict the conducted EMI level in a DC/DC converter. Measurement methodology was done using a network analyzer in order to evaluate the equivalent impedance model of each converter element. The full circuit model is then implemented in the Saber-trademark simulation tool using time domain simulation followed by fast Fourier transformation (FFT) in the frequency range 150 KHz -100 MHz. A comparison between simulation results and those obtained by measurements is used to validate the developed model. (author)

  15. Limitations of the dual voltage clamp method in assaying conductance and kinetics of gap junction channels

    NARCIS (Netherlands)

    Wilders, R.; Jongsma, H. J.

    1992-01-01

    The electrical properties of gap junctions in cell pairs are usually studied by means of the dual voltage clamp method. The voltage across the junctional channels, however, cannot be controlled adequately due to an artificial resistance and a natural resistance, both connected in series with the gap

  16. Numerical modelling of channel processes and analysis of possible channel improvement measures on the Lena River near city Yakutsk

    Science.gov (United States)

    Krylenko, Inna; Belikov, Vitaly; Zavadskii, Aleksander; Borisova, Natalya; Golovlyov, Pavel; Rumyantsev, Alexey

    2017-04-01

    City Yakutsk (administrative, culture and industrial center of the North East of Russia) situated on the left bank of large Russian river Lena last decades has faced with many problems, concerning intensive channel processes. Most dramatic among them are sediment accumulation near main water intake structure, supplying city Yakutsk by the drinking water, and deterioration in conditions of the navigation roots to the main city ports. Hydrodynamic modelling has been chosen as the main tool for analyses of the modern tendencies in channel processes and for the evaluation of possible channel improvement measures efficiency. STREAM_2D program complex (authors V. Belikov et al.), which is based on the numerical solution of two-dimensional Saint-Venant equations on a hybrid curvilinear quadrangular and rectangular mesh and take into account sediment transport, was used for the simulations. Detailed field data about water regime of the Lena river, bathymetry of the channels and topography of the floodplains was collected for model developing. Model area has covered 75 km of the Lena river valley including branched channels and wide floodplain from Tabaga to Kangalassy gauge cites. Data of these stations were used for model boundary conditions assigning. Data of gauge station city Yakutsk as well as measured during field campaign water levels and flow velocities was taken into account for model calibration and validation. Results of modelling has demonstrated close correspondence with observed water levels and discharges distribution between channel branches for different hydrological situations. Different combinations of hydrographs of 1, 10, 50% exceedance probability was used as input for modelling of channel deformations. Simulation results has shown that in future 10 years aligning of water discharges distribution between main Lena river branches near Yakutsk is possible, that is a positive tendency from the point of view of water supply of the city. More than 15

  17. Leaching of Conductive Species: Implications to Measurements of Electrical Resistivity.

    Science.gov (United States)

    Spragg, R; Jones, S; Bu, Y; Lu, Y; Bentz, D; Snyder, K; Weiss, J

    2017-05-01

    Electrical tests have been used to characterize the microstructure of porous materials, the measured electrical response being determined by the contribution of the microstructure (porosity and tortuosity) and the electrical properties of the solution (conductivity of the pore solution) inside the pores of the material. This study has shown how differences in concentration between the pore solution (i.e., the solution in the pores) and the storage solution surrounding the test specimen leads to significant transport (leaching) of the conductive ionic species between the pore solution and the storage solution. Leaching influences the resistivity of the pore solution, thereby influencing electrical measurements on the bulk material from either a surface or uniaxial bulk resistance test. This paper has three main conclusions: 1.) Leaching of conductive species does occur with concentration gradients and that a diffusion based approach can be used to estimate the time scale associated with this change. 2.) Leaching of ions in the pore solution can influence resistivity measurements, and the ratio of surface to uniaxial resistivity can be used as a method to assess the presence of leaching and 3.) An estimation of the magnitude of leaching for standardized tests of cementitious materials.

  18. Aspirated capacitor measurements of air conductivity and ion mobility spectra

    International Nuclear Information System (INIS)

    Aplin, K.L.

    2005-01-01

    Measurements of ions in atmospheric air are used to investigate atmospheric electricity and particulate pollution. Commonly studied ion parameters are (1) air conductivity, related to the total ion number concentration, and (2) the ion mobility spectrum, which varies with atmospheric composition. The physical principles of air ion instrumentation are long established. A recent development is the computerized aspirated capacitor, which measures ions from (a) the current of charged particles at a sensing electrode, and (b) the rate of charge exchange with an electrode at a known initial potential, relaxing to a lower potential. As the voltage decays, only ions of higher and higher mobility are collected by the central electrode and contribute to the further decay of the voltage. This enables extension of the classical theory to calculate ion mobility spectra by inverting voltage decay time series. In indoor air, ion mobility spectra determined from both the voltage decay inversion, and an established voltage switching technique, were compared and shown to be of similar shape. Air conductivities calculated by integration were: 5.3±2.5 and 2.7±1.1 fSm -1 , respectively, with conductivity determined to be 3 fSm -1 by direct measurement at a constant voltage. Applications of the relaxation potential inversion method include air ion mobility spectrum retrieval from historical data, and computation of ion mobility spectra in planetary atmospheres

  19. KCNN Genes that Encode Small-Conductance Ca2+-Activated K+ Channels Influence Alcohol and Drug Addiction.

    Science.gov (United States)

    Padula, Audrey E; Griffin, William C; Lopez, Marcelo F; Nimitvilai, Sudarat; Cannady, Reginald; McGuier, Natalie S; Chesler, Elissa J; Miles, Michael F; Williams, Robert W; Randall, Patrick K; Woodward, John J; Becker, Howard C; Mulholland, Patrick J

    2015-07-01

    Small-conductance Ca(2+)-activated K(+) (KCa2) channels control neuronal excitability and synaptic plasticity, and have been implicated in substance abuse. However, it is unknown if genes that encode KCa2 channels (KCNN1-3) influence alcohol and drug addiction. In the present study, an integrative functional genomics approach shows that genetic datasets for alcohol, nicotine, and illicit drugs contain the family of KCNN genes. Alcohol preference and dependence QTLs contain KCNN2 and KCNN3, and Kcnn3 transcript levels in the nucleus accumbens (NAc) of genetically diverse BXD strains of mice predicted voluntary alcohol consumption. Transcript levels of Kcnn3 in the NAc negatively correlated with alcohol intake levels in BXD strains, and alcohol dependence enhanced the strength of this association. Microinjections of the KCa2 channel inhibitor apamin into the NAc increased alcohol intake in control C57BL/6J mice, while spontaneous seizures developed in alcohol-dependent mice following apamin injection. Consistent with this finding, alcohol dependence enhanced the intrinsic excitability of medium spiny neurons in the NAc core and reduced the function and protein expression of KCa2 channels in the NAc. Altogether, these data implicate the family of KCNN genes in alcohol, nicotine, and drug addiction, and identify KCNN3 as a mediator of voluntary and excessive alcohol consumption. KCa2.3 channels represent a promising novel target in the pharmacogenetic treatment of alcohol and drug addiction.

  20. Inwardly Rectifying Potassium (Kir) Channels Represent a Critical Ion Conductance Pathway in the Nervous Systems of Insects.

    Science.gov (United States)

    Chen, Rui; Swale, Daniel R

    2018-01-25

    A complete understanding of the physiological pathways critical for proper function of the insect nervous system is still lacking. The recent development of potent and selective small-molecule modulators of insect inward rectifier potassium (Kir) channels has enabled the interrogation of the physiological role and toxicological potential of Kir channels within various insect tissue systems. Therefore, we aimed to highlight the physiological and functional role of neural Kir channels the central nervous system, muscular system, and neuromuscular system through pharmacological and genetic manipulations. Our data provide significant evidence that Drosophila neural systems rely on the inward conductance of K + ions for proper function since pharmacological inhibition and genetic ablation of neural Kir channels yielded dramatic alterations of the CNS spike discharge frequency and broadening and reduced amplitude of the evoked EPSP at the neuromuscular junction. Based on these data, we conclude that neural Kir channels in insects (1) are critical for proper function of the insect nervous system, (2) represents an unexplored physiological pathway that is likely to shape the understanding of neuronal signaling, maintenance of membrane potentials, and maintenance of the ionic balance of insects, and (3) are capable of inducing acute toxicity to insects through neurological poisoning.

  1. Identification of the functional binding pocket for compounds targeting small-conductance Ca²⁺-activated potassium channels.

    Science.gov (United States)

    Zhang, Miao; Pascal, John M; Schumann, Marcel; Armen, Roger S; Zhang, Ji-Fang

    2012-01-01

    Small- and intermediate-conductance Ca(2+)-activated potassium channels, activated by Ca(2+)-bound calmodulin, have an important role in regulating membrane excitability. These channels are also linked to clinical abnormalities. A tremendous amount of effort has been devoted to developing small molecule compounds targeting these channels. However, these compounds often suffer from low potency and lack of selectivity, hindering their potential for clinical use. A key contributing factor is the lack of knowledge of the binding site(s) for these compounds. Here we demonstrate by X-ray crystallography that the binding pocket for the compounds of the 1-ethyl-2-benzimidazolinone (1-EBIO) class is located at the calmodulin-channel interface. We show that, based on structure data and molecular docking, mutations of the channel can effectively change the potency of these compounds. Our results provide insight into the molecular nature of the binding pocket and its contribution to the potency and selectivity of the compounds of the 1-EBIO class.

  2. Identification of the functional binding pocket for compounds targeting small-conductance Ca2+-activated potassium channels

    Science.gov (United States)

    Zhang, Miao; Pascal, John M.; Schumann, Marcel; Armen, Roger S.; Zhang, Ji-fang

    2012-01-01

    Small- and intermediate-conductance Ca2+-activated potassium channels, activated by Ca2+-bound calmodulin, play an important role in regulating membrane excitability. These channels are also linked to clinical abnormalities. A tremendous amount of effort has been devoted to developing small molecule compounds targeting these channels. However, these compounds often suffer from low potency and lack of selectivity, hindering their potentials for clinical use. A key contributing factor is the lack of knowledge of the binding site(s) for these compounds. Here we demonstrate by X-ray crystallography that the binding pocket for the compounds of the 1-EBIO class is located at the calmodulin-channel interface. We show that, based on structure data and molecular docking, mutations of the channel can effectively change the potency of these compounds. Our results provide insight into the molecular nature of the binding pocket and its contribution to the potency and selectivity of the compounds of the 1-EBIO class. PMID:22929778

  3. Highly selective water channel activity measured by voltage clamp: analysis of planar lipid bilayers reconstituted with purified AqpZ.

    Science.gov (United States)

    Pohl, P; Saparov, S M; Borgnia, M J; Agre, P

    2001-08-14

    Aquaporins are membrane channels selectively permeated by water or water plus glycerol. Conflicting reports have described ion conductance associated with some water channels, raising the question of whether ion conductance is a general property of the aquaporin family. To clarify this question, a defined system was developed to simultaneously measure water permeability and ion conductance. The Escherichia coli water channel aquaporin-Z (AqpZ) was studied, because it is a highly stable tetramer. Planar lipid bilayers were formed from unilamellar vesicles containing purified AqpZ. The hydraulic conductivity of bilayers made from the total extract of E. coli lipids increased 3-fold if reconstituted with AqpZ, but electric conductance was unchanged. No channel activity was detected under voltage-clamp conditions, indicating that less than one in 10(9) transport events is electrogenic. Microelectrode measurements were simultaneously undertaken adjacent to the membrane. Changes in sodium concentration profiles accompanying transmembrane water flow permitted calculation of the activation energies: 14 kcal/mol for protein-free lipid bilayers and 4 kcal/mol for lipid bilayers containing AqpZ. Neither the water permeability nor the electric conductivity exhibited voltage dependence. This sensitive system demonstrated that AqpZ is permeated by water but not charged ions and should permit direct analyses of putative electrogenic properties of other aquaporins.

  4. Atomistic Modeling of Ion Conduction through the Voltage-Sensing Domain of the Shaker K+ Ion Channel.

    Science.gov (United States)

    Wood, Mona L; Freites, J Alfredo; Tombola, Francesco; Tobias, Douglas J

    2017-04-20

    Voltage-sensing domains (VSDs) sense changes in the membrane electrostatic potential and, through conformational changes, regulate a specific function. The VSDs of wild-type voltage-dependent K + , Na + , and Ca 2+ channels do not conduct ions, but they can become ion-permeable through pathological mutations in the VSD. Relatively little is known about the underlying mechanisms of conduction through VSDs. The most detailed studies have been performed on Shaker K + channel variants in which ion conduction through the VSD is manifested in electrophysiology experiments as a voltage-dependent inward current, the so-called omega current, which appears when the VSDs are in their resting state conformation. Only monovalent cations appear to permeate the Shaker VSD via a pathway that is believed to be, at least in part, the same as that followed by the S4 basic side chains during voltage-dependent activation. We performed μs-time scale atomistic molecular dynamics simulations of a cation-conducting variant of the Shaker VSD under applied electric fields in an experimentally validated resting-state conformation, embedded in a lipid bilayer surrounded by solutions containing guanidinium chloride or potassium chloride. Our simulations provide insights into the Shaker VSD permeation pathway, the protein-ion interactions that control permeation kinetics, and the mechanism of voltage-dependent activation of voltage-gated ion channels.

  5. An intermediate-conductance Ca2+-activated K+ channel is important for secretion in pancreatic duct cells

    DEFF Research Database (Denmark)

    Hayashi, Mikio; Wang, Jing; Hede, Susanne Edeling

    2012-01-01

    2; Slack; Slick; and an intermediate-conductance Ca(2+)-activated K(+) (IK) channel (K(Ca)3.1). The following functional studies were focused on the IK channel. 5,6-Dichloro-1-ethyl-1,3-dihydro-2H-benzimidazole-2-one (DC-EBIO), an activator of IK channel, increased equivalent short-circuit current...

  6. Scrutiny of underdeveloped nanofluid MHD flow and heat conduction in a channel with porous walls

    Directory of Open Access Journals (Sweden)

    M. Fakour

    2014-11-01

    Full Text Available In this paper, laminar fluid flow and heat transfer in channel with permeable walls in the presence of a transverse magnetic field is investigated. Least square method (LSM for computing approximate solutions of nonlinear differential equations governing the problem. We have tried to show reliability and performance of the present method compared with the numerical method (Runge–Kutta fourth-rate to solve this problem. The influence of the four dimensionless numbers: the Hartmann number, Reynolds number, Prandtl number and Eckert number on non-dimensional velocity and temperature profiles are considered. The results show analytical present method is very close to numerically method. In general, increasing the Reynolds and Hartman number is reduces the nanofluid flow velocity in the channel and the maximum amount of temperature increase and increasing the Prandtl and Eckert number will increase the maximum amount of theta.

  7. Silicate bonding properties: Investigation through thermal conductivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzini, M; Cesarini, E; Cagnoli, G; Campagna, E; Losurdo, G; Martelli, F; Piergiovanni, F; Vetrano, F [INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Haughian, K; Hough, J; Martin, I; Reid, S; Rowan, S; Veggel, A A van, E-mail: lorenzini@fi.infn.i [SUPA, University of Glasgow, Department of Physics and Astronomy, Kelvin Building G12 8QQ Glasgow, Scotland (United Kingdom)

    2010-05-01

    A direct approach to reduce the thermal noise contribution to the sensitivity limit of a GW interferometric detector is the cryogenic cooling of the mirrors and mirrors suspensions. Future generations of detectors are foreseen to implement this solution. Silicon has been proposed as a candidate material, thanks to its very low intrinsic loss angle at low temperatures and due to its very high thermal conductivity, allowing the heat deposited in the mirrors by high power lasers to be efficiently extracted. To accomplish such a scheme, both mirror masses and suspension elements must be made of silicon, then bonded together forming a quasi-monolithic stage. Elements can be assembled using hydroxide-catalysis silicate bonding, as for silica monolithic joints. The effect of Si to Si bonding on suspension thermal conductance has therefore to be experimentally studied. A measurement of the effect of silicate bonding on thermal conductance carried out on 1 inch thick silicon bonded samples, from room temperature down to 77 K, is reported. In the explored temperature range, the silicate bonding does not seem to affect in a relevant way the sample conductance.

  8. Limitations of the dual voltage clamp method in assaying conductance and kinetics of gap junction channels

    OpenAIRE

    Wilders, R.; Jongsma, H.J.

    1992-01-01

    The electrical properties of gap junctions in cell pairs are usually studied by means of the dual voltage clamp method. The voltage across the junctional channels, however, cannot be controlled adequately due to an artificial resistance and a natural resistance, both connected in series with the gap junction. The access resistances to the cell interior of the recording pipettes make up the artificial resistance. The natural resistance consists of the cytoplasmic access resistances to the tigh...

  9. Efficiency criterion for teleportation via channel matrix, measurement matrix and collapsed matrix

    Directory of Open Access Journals (Sweden)

    Xin-Wei Zha

    Full Text Available In this paper, three kinds of coefficient matrixes (channel matrix, measurement matrix, collapsed matrix associated with the pure state for teleportation are presented, the general relation among channel matrix, measurement matrix and collapsed matrix is obtained. In addition, a criterion for judging whether a state can be teleported successfully is given, depending on the relation between the number of parameter of an unknown state and the rank of the collapsed matrix. Keywords: Channel matrix, Measurement matrix, Collapsed matrix, Teleportation

  10. Phase transition traced by conductivity measurements: quantitative analysis

    DEFF Research Database (Denmark)

    Keding, Ralf; Ruessel, Christian; Tauch, Diana

    2008-01-01

    starting from the electrodes. The change in the conductivity as a function of the temperature was fitted with VFT-equation for both the melt and the crystalline phase. An extrapolation of the resistance of the melt as well as of the crystalline material allows to separate the temperature dependent changes...... of conductivity and the resistance changes caused by phase transformation. This enables to determine the crystal growth velocity in the temperature range between 750 and 860 degrees C in a single experiment.......The measurement of the crystal growth velocity is carried out by analysing the change in the resistivity of the sample. The calculation of the crystal growth velocity is developed for crystal formation in the volume, crystal growth initiated at the electrodes as well as perpendicular...

  11. Calibrating electromagnetic induction conductivities with time-domain reflectometry measurements

    Science.gov (United States)

    Dragonetti, Giovanna; Comegna, Alessandro; Ajeel, Ali; Piero Deidda, Gian; Lamaddalena, Nicola; Rodriguez, Giuseppe; Vignoli, Giulio; Coppola, Antonio

    2018-02-01

    This paper deals with the issue of monitoring the spatial distribution of bulk electrical conductivity, σb, in the soil root zone by using electromagnetic induction (EMI) sensors under different water and salinity conditions. To deduce the actual distribution of depth-specific σb from EMI apparent electrical conductivity (ECa) measurements, we inverted the data by using a regularized 1-D inversion procedure designed to manage nonlinear multiple EMI-depth responses. The inversion technique is based on the coupling of the damped Gauss-Newton method with truncated generalized singular value decomposition (TGSVD). The ill-posedness of the EMI data inversion is addressed by using a sharp stabilizer term in the objective function. This specific stabilizer promotes the reconstruction of blocky targets, thereby contributing to enhance the spatial resolution of the EMI results in the presence of sharp boundaries (otherwise smeared out after the application of more standard Occam-like regularization strategies searching for smooth solutions). Time-domain reflectometry (TDR) data are used as ground-truth data for calibration of the inversion results. An experimental field was divided into four transects 30 m long and 2.8 m wide, cultivated with green bean, and irrigated with water at two different salinity levels and using two different irrigation volumes. Clearly, this induces different salinity and water contents within the soil profiles. For each transect, 26 regularly spaced monitoring soundings (1 m apart) were selected for the collection of (i) Geonics EM-38 and (ii) Tektronix reflectometer data. Despite the original discrepancies in the EMI and TDR data, we found a significant correlation of the means and standard deviations of the two data series; in particular, after a low-pass spatial filtering of the TDR data. Based on these findings, this paper introduces a novel methodology to calibrate EMI-based electrical conductivities via TDR direct measurements. This

  12. Phase transition traced by conductivity measurements: quantitative analysis

    DEFF Research Database (Denmark)

    Keding, Ralf; Ruessel, Christian; Tauch, Diana

    2008-01-01

    to the electrodes, all in a cylindrical geometry. The electrical resistivity of a sample in the system BaAl2B2O7 was measured during cooling between liquidus temperature (T-l) and transformation temperature (T-g) using a fixed frequency of 3.7 Hz. The melt crystallised in this temperature range during cooling...... of conductivity and the resistance changes caused by phase transformation. This enables to determine the crystal growth velocity in the temperature range between 750 and 860 degrees C in a single experiment....

  13. Spontaneous and CRH-Induced Excitability and Calcium Signaling in Mice Corticotrophs Involves Sodium, Calcium, and Cation-Conducting Channels

    Czech Academy of Sciences Publication Activity Database

    Zemková, Hana; Tomič, M.; Kučka, M.; Aguilera, G.; Stojilkovic, S. S.

    2016-01-01

    Roč. 157, č. 4 (2016), s. 1576-1589 ISSN 0013-7227 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : action potential * background sodium conductance * bursting activity * cation -conducting channels * cytosolic calcium concentration * resting membrane potential Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 4.286, year: 2016

  14. Functional suppression of Kcnq1 leads to early sodium channel remodelling and cardiac conduction system dysmorphogenesis

    Czech Academy of Sciences Publication Activity Database

    De la Rosa, A. J.; Domínguez, J. N.; Sedmera, D.; Šaňková, Barbora; Hove-Madsen, L.; Franco, D.; Aránega, A. E.

    2013-01-01

    Roč. 98, č. 3 (2013), s. 504-514 ISSN 0008-6363 R&D Projects: GA ČR(CZ) GA304/08/0615; GA ČR(CZ) GAP302/11/1308; GA ČR(CZ) GD204/09/H084; GA ČR(CZ) GA13-12412S Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : ion channels * Long-QT syndrome * sudden death * cardiac hypertrophy Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 5.808, year: 2013

  15. TWIK-1 two-pore domain potassium channels change ion selectivity and conduct inward leak sodium currents in hypokalemia.

    Science.gov (United States)

    Ma, Liqun; Zhang, Xuexin; Chen, Haijun

    2011-06-07

    Background potassium (K+) channels, which are normally selectively permeable to K+, maintain the cardiac resting membrane potential at around -80 mV. In subphysiological extracellular K+ concentrations ([K+]o), which occur in pathological hypokalemia, the resting membrane potential of human cardiomyocytes can depolarize to around -50 mV, whereas rat and mouse cardiomyocytes become hyperpolarized, consistent with the Nernst equation for K+. This paradoxical depolarization of cardiomyocytes in subphysiological [K+]o, which may contribute to cardiac arrhythmias, is thought to involve an inward leak sodium (Na+) current. Here, we show that human cardiac TWIK-1 (also known as K2P1) two-pore domain K+ channels change ion selectivity, becoming permeable to external Na+, and conduct inward leak Na+ currents in subphysiological [K+]o. A specific threonine residue (Thr118) within the pore selectivity sequence TxGYG was required for this altered ion selectivity. Mouse cardiomyocyte-derived HL-1 cells exhibited paradoxical depolarization with ectopic expression of TWIK-1 channels, whereas TWIK-1 knockdown in human spherical primary cardiac myocytes eliminated paradoxical depolarization. These findings indicate that ion selectivity of TWIK-1 K+ channels changes during pathological hypokalemia, elucidate a molecular basis for inward leak Na+ currents that could trigger or contribute to cardiac paradoxical depolarization in lowered [K+]o, and identify a mechanism for regulating cardiac excitability.

  16. Two Salt Bridges Differentially Contribute to the Maintenance of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Channel Function*

    Science.gov (United States)

    Cui, Guiying; Freeman, Cody S.; Knotts, Taylor; Prince, Chengyu Z.; Kuang, Christopher; McCarty, Nael A.

    2013-01-01

    Previous studies have identified two salt bridges in human CFTR chloride ion channels, Arg352-Asp993 and Arg347-Asp924, that are required for normal channel function. In the present study, we determined how the two salt bridges cooperate to maintain the open pore architecture of CFTR. Our data suggest that Arg347 not only interacts with Asp924 but also interacts with Asp993. The tripartite interaction Arg347-Asp924-Asp993 mainly contributes to maintaining a stable s2 open subconductance state. The Arg352-Asp993 salt bridge, in contrast, is involved in stabilizing both the s2 and full (f) open conductance states, with the main contribution being to the f state. The s1 subconductance state does not require either salt bridge. In confirmation of the role of Arg352 and Asp993, channels bearing cysteines at these sites could be latched into a full open state using the bifunctional cross-linker 1,2-ethanediyl bismethanethiosulfonate, but only when applied in the open state. Channels remained latched open even after washout of ATP. The results suggest that these interacting residues contribute differently to stabilizing the open pore in different phases of the gating cycle. PMID:23709221

  17. Channel Bow in Boiling Water Reactors - Hot Cell Examination Results and Correlation to Measured Bow

    International Nuclear Information System (INIS)

    Mahmood, S.T.; Lin, Y.P.; Dubecky, M.A.; Edsinger, K.; Mader, E.V.

    2007-01-01

    An increase in frequency of fuel channel-control blade interference has been observed in Boiling Water Reactors (BWR) in recent years. Many of the channels leading to interference were found to bow towards the control blade in a manner that was inconsistent with the expected bow due to other effects. The pattern of bow appeared to indicate a new channel bow mechanism that differed from the predominant bow mechanism caused by differential growth due to fast-fluence gradients. In order to investigate this new type of channel bow, coupons from several channels with varying degrees of bow were returned to the GE Vallecitos Nuclear Center (VNC) for Post-Irradiation Examination (PIE). This paper describes the characteristics of channel corrosion and hydrogen pickup observed, and relates the observations to the channel exposure level, control history, and measured channel bow. The channels selected for PIE had exposures in the range of 36-48 GWd/MTU and covered a wide range of measured bow. The coupons were obtained at 4 elevations from opposing channel sides adjacent and away from the control blade. The PIE performed on these coupons included visual examination, metallography, and hydrogen concentration measurements. A new mechanism of control-blade shadow corrosion-induced channel bow was found to correlate with differences in the extent of corrosion and corresponding differences in the hydrogen concentration between opposite sides of the channels. The increased corrosion on the control blade sides was found to be dependent on the level of control early in the life of the channel. The contributions of other potential factors leading to increased channel bow and channel-control blade interference are also discussed in this paper. (authors)

  18. Sub-micrometer fluidic channel for measuring photon emitting entities

    Science.gov (United States)

    Stavis, Samuel M; Edel, Joshua B; Samiee, Kevan T; Craighead, Harold G

    2014-11-18

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  19. The Activation Effect of Hainantoxin-I, a Peptide Toxin from the Chinese Spider, Ornithoctonus hainana, on Intermediate-Conductance Ca2+-Activated K+ Channels

    Directory of Open Access Journals (Sweden)

    Pengfei Huang

    2014-08-01

    Full Text Available Intermediate-conductance Ca2+-activated K+ (IK channels are calcium/calmodulin-regulated voltage-independent K+ channels. Activation of IK currents is important in vessel and respiratory tissues, rendering the channels potential drug targets. A variety of small organic molecules have been synthesized and found to be potent activators of IK channels. However, the poor selectivity of these molecules limits their therapeutic value. Venom-derived peptides usually block their targets with high specificity. Therefore, we searched for novel peptide activators of IK channels by testing a series of toxins from spiders. Using electrophysiological experiments, we identified hainantoxin-I (HNTX-I as an IK-channel activator. HNTX-I has little effect on voltage-gated Na+ and Ca2+ channels from rat dorsal root ganglion neurons and on the heterologous expression of voltage-gated rapidly activating delayed rectifier K+ channels (human ether-à-go-go-related gene; human ERG in HEK293T cells. Only 35.2% ± 0.4% of the currents were activated in SK channels, and there was no effect on BK channels. We demonstrated that HNTX-I was not a phrenic nerve conduction blocker or acutely toxic. This is believed to be the first report of a peptide activator effect on IK channels. Our study suggests that the activity and selectivity of HNTX-I on IK channels make HNTX-I a promising template for designing new drugs for cardiovascular diseases.

  20. Innovation of fission gas release and thermal conductivity measurement methods

    International Nuclear Information System (INIS)

    Van der Meer, K.; Soboler, V.

    1998-01-01

    This presentation described two innovative measurement methods being currently developed at SCK-CEN in order to support the modeling of fuel performance. The first one is an acoustic method to measure the fission gas release in a fuel rod in a non destructive way. The total rod pressure is determined by generating a heat pulse causing a pressure wave that propagates through the gas to an ultrasound transducer. The final pulse width being proportional to the pressure, the latter can thus be determined. The measurement of the acoustic resonance frequency at fixed temperatures enables the distinction between different gas components. The second method is a non-stationary technique to investigate the thermal properties of the fuel rod, like thermal conductivity, diffusivity and heat capacity. These properties are derived from the amplitude and the phase shift of the fuel centre temperature response induced by a periodic temperature variation. These methods did not reveal any physical limitations for the practical applicability. Furthermore, they are rather simple. Preliminary investigations have proven both methods to be more accurate than techniques usually utilized. (author)

  1. Effect of wall conductances on hydromagnetic flow and heat transfer in a rotating channel

    International Nuclear Information System (INIS)

    Mazumder, B.S.

    1977-01-01

    Wall conductance effects on the hydromagnetic flow and heat transfer between two parallel plates in a rotating frame of reference has been studied when the liquid is permeated by a transverse magnetic field. An exact solution of the governing equation has been obtained. It is found that the velocity current density and the temperature depend only on the sum of the wall conductances phi 1 + phi 2 = phi but magnetic field depends on the individual values of phi 1 and phi 2 where phi 1 and phi 2 are respectively the wall conductance ratios of the upper and lower walls. (Auth.)

  2. Broadband Mm-Wave OFDM Communications in Doubly Selective Channel: Performance Evaluation Using Measured Mm-Wave Channel

    DEFF Research Database (Denmark)

    Chen, Xiaoming; Fan, Wei; Pedersen, Gert F.

    2018-01-01

    coefficients of the broadband mm-wave channel do not follow Gaussian distribution due to the broad bandwidth. It is also shown that, given a cyclic prefix (CP) length for a certain delay spread, an effective PN mitigation scheme enables a PN corrupted OFDM system to function with small subcarrier spacing and......In this work, we evaluate the performance of the broadband millimeter-wave (mm-wave) OFDM system in the presence of phase noise (PN) of phase-locked loop based oscillator and delay spread of measured mm-wave channel. It is shown, using Akaike's information criterion, that the channel tap......, therefore, small CP overhead, with only slight degradation of the error rate performance....

  3. Overexpression of the Large-Conductance, Ca2+-Activated K+ (BK) Channel Shortens Action Potential Duration in HL-1 Cardiomyocytes.

    Science.gov (United States)

    Stimers, Joseph R; Song, Li; Rusch, Nancy J; Rhee, Sung W

    2015-01-01

    Long QT syndrome is characterized by a prolongation of the interval between the Q wave and the T wave on the electrocardiogram. This abnormality reflects a prolongation of the ventricular action potential caused by a number of genetic mutations or a variety of drugs. Since effective treatments are unavailable, we explored the possibility of using cardiac expression of the large-conductance, Ca2+-activated K+ (BK) channel to shorten action potential duration (APD). We hypothesized that expression of the pore-forming α subunit of human BK channels (hBKα) in HL-1 cells would shorten action potential duration in this mouse atrial cell line. Expression of hBKα had minimal effects on expression levels of other ion channels with the exception of a small but significant reduction in Kv11.1. Patch-clamped hBKα expressing HL-1 cells exhibited an outward voltage- and Ca2+-sensitive K+ current, which was inhibited by the BK channel blocker iberiotoxin (100 nM). This BK current phenotype was not detected in untransfected HL-1 cells or in HL-1 null cells sham-transfected with an empty vector. Importantly, APD in hBKα-expressing HL-1 cells averaged 14.3 ± 2.8 ms (n = 10), which represented a 53% reduction in APD compared to HL-1 null cells lacking BKα expression. APD in the latter cells averaged 31.0 ± 5.1 ms (n = 13). The shortened APD in hBKα-expressing cells was restored to normal duration by 100 nM iberiotoxin, suggesting that a repolarizing K+ current attributed to BK channels accounted for action potential shortening. These findings provide initial proof-of-concept that the introduction of hBKα channels into a cardiac cell line can shorten APD, and raise the possibility that gene-based interventions to increase hBKα channels in cardiac cells may hold promise as a therapeutic strategy for long QT syndrome.

  4. Measurement of the heat transfer coefficient in the dimpled channel: effects of dimple arrangement and channel height

    International Nuclear Information System (INIS)

    Shin, So Min; Lee, Ki Seon; Park, Seoung Duck; Kwak, Jae Su

    2009-01-01

    Heat transfer coefficients were measured in a channel with one side dimpled surface. The sphere type dimples were fabricated, and the diameter (D) and the depth of dimple was 16 mm and 4 mm, respectively. Two channel heights of about 0.6D and 1.2D, two dimple configurations were tested. The Reynolds number based on the channel hydraulic diameter was varied from 30000 to 50000. The improved hue detection based transient liquid crystal technique was used in the heat transfer measurement. Heat transfer measurement results showed that high heat transfer was induced downstream of the dimples due to flow reattachment. Due to the flow recirculation on the upstream side in the dimple, the heat transfer coefficient was very low. As the Reynolds increased, the overall heat transfer coefficients also increased. With the same dimple arrangement, the heat transfer coefficients and the thermal performance factors were higher for the lower channel height. As the distance between the dimples became smaller, the overall heat transfer coefficient and the thermal performance factors increased

  5. Compartmentalized beta subunit distribution determines characteristics and ethanol sensitivity of somatic, dendritic, and terminal large-conductance calcium-activated potassium channels in the rat central nervous system.

    Science.gov (United States)

    Wynne, P M; Puig, S I; Martin, G E; Treistman, S N

    2009-06-01

    Neurons are highly differentiated and polarized cells, whose various functions depend upon the compartmentalization of ion channels. The rat hypothalamic-neurohypophysial system (HNS), in which cell bodies and dendrites reside in the hypothalamus, physically separated from their nerve terminals in the neurohypophysis, provides a particularly powerful preparation in which to study the distribution and regional properties of ion channel proteins. Using electrophysiological and immunohistochemical techniques, we characterized the large-conductance calcium-activated potassium (BK) channel in each of the three primary compartments (soma, dendrite, and terminal) of HNS neurons. We found that dendritic BK channels, in common with somatic channels but in contrast to nerve terminal channels, are insensitive to iberiotoxin. Furthermore, analysis of dendritic BK channel gating kinetics indicates that they, like somatic channels, have fast activation kinetics, in contrast to the slow gating of terminal channels. Dendritic and somatic channels are also more sensitive to calcium and have a greater conductance than terminal channels. Finally, although terminal BK channels are highly potentiated by ethanol, somatic and dendritic channels are insensitive to the drug. The biophysical and pharmacological properties of somatic and dendritic versus nerve terminal channels are consistent with the characteristics of exogenously expressed alphabeta1 versus alphabeta4 channels, respectively. Therefore, one possible explanation for our findings is a selective distribution of auxiliary beta1 subunits to the somatic and dendritic compartments and beta4 to the terminal compartment. This hypothesis is supported immunohistochemically by the appearance of distinct punctate beta1 or beta4 channel clusters in the membrane of somatic and dendritic or nerve terminal compartments, respectively.

  6. Development of concentration measurement system in a mini-channel using a local NMR sensor

    International Nuclear Information System (INIS)

    Ogawa, Kuniyasu; Haishi, Tomoyuki

    2008-01-01

    A local NMR sensor to measure methanol concentration of fluid flowing in a mini-channel was developed. The principle of the methanol sensor is based on the chemical shift of CH and OH species under high magnetic field. The sensor consists of a planar surface coil of 0.60 mm inside diameter. Using the sensors, local methanol concentration of water-methanol mixture in the mini-channel of 3.0 mm width and 1.5 mm depth was measured. The effects of flow velocity in the channel and the gravity direction on the methanol concentration distribution in the channel were investigated experimentally. (author)

  7. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    International Nuclear Information System (INIS)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Beevi, Akbar Sait Hameedha; Priya, Radhakrishnan Jeeva; Maduraiveeran, Govindhan

    2015-01-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices. (paper)

  8. Measuring lateral saturated soil hydraulic conductivity at different spatial scales

    Science.gov (United States)

    Di Prima, Simone; Marrosu, Roberto; Pirastru, Mario; Niedda, Marcello

    2017-04-01

    Among the soil hydraulic properties, saturated soil hydraulic conductivity, Ks, is particularly important since it controls many hydrological processes. Knowledge of this soil property allows estimation of dynamic indicators of the soil's ability to transmit water down to the root zone. Such dynamic indicators are valuable tools to quantify land degradation and developing 'best management' land use practice (Castellini et al., 2016; Iovino et al., 2016). In hillslopes, lateral saturated soil hydraulic conductivity, Ks,l, is a key factor since it controls subsurface flow. However, Ks,l data collected by point-scale measurements, including infiltrations tests, could be unusable for interpreting field hydrological processes and particularly subsurface flow in hillslopes. Therefore, they are generally not representative of subsurface processes at hillslope-scale due mainly to soil heterogeneities and the unknown total extent and connectivity of macropore network in the porous medium. On the other hand, large scale Ks,l measurements, which allow to average soil heterogeneities, are difficult and costly, thus remain rare. Reliable Ks,l values should be measured on a soil volume similar to the representative elementary volume (REV) in order to incorporate the natural heterogeneity of the soil. However, the REV may be considered site-specific since it is expected to increase for soils with macropores (Brooks et al., 2004). In this study, laboratory and in-situ Ks,l values are compared in order to detect the dependency Ks,l from the spatial scale of investigation. The research was carried out at a hillslope located in the Baratz Lake watershed, in northwest Sardinia, Italy, characterized by degraded vegetation (grassland established after fire or clearing of the maquis). The experimental area is about 60 m long, with an extent of approximately 2000 m2, and a mean slope of 30%. The soil depth is about 35 to 45 cm. The parent material is a very dense grayish, altered

  9. Abnormal resistance switching behaviours of NiO thin films: possible occurrence of both formation and rupturing of conducting channels

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chunli; Chae, S C; Chang, S H; Lee, S B; Noh, T W [ReCOE and FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Lee, J S; Kahng, B [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, D-W [Division of Nano Sciences and Department of Physics, Ewha Womens University, Seoul 120-750 (Korea, Republic of); Jung, C U [Department of Physics, Hankuk University of Foreign Studies, Yongin, Gyeonggi-do 449-791 (Korea, Republic of); Seo, S; Ahn, S-E [Samsung Advanced Institute of Technology, Suwon 440-600 (Korea, Republic of)], E-mail: twnoh@snu.ac.kr

    2009-01-07

    We report a detailed study on the abnormal resistance switching behaviours observed in NiO thin films which show unipolar resistance switching phenomena. During the RESET process, in which the NiO film changed from a low resistance state to a high resistance state, we sometimes observed that the resistance became smaller than the initial value. We simulated the resistance switching by using a random circuit breaker network model. We found that local conducting channels could be formed as well as ruptured during the RESET process, which result in the occurrence of such abnormal switching behaviours.

  10. Measurement of the heavy water level in the fuel channels of the RA reactor - Annex 11

    International Nuclear Information System (INIS)

    Nikolic, M.

    1964-01-01

    The objective of measuring the heavy water level in the reactor channels was to verify experimentally the possibilities of reactor cooling with parallel operation of heavy water pumps od 1500 rotations/min at nominal power of 6.5 MW. Measurements were done in 2 periphery and 2 central fuel channels with pumps speed 1500, 1800 and 3000 rotations/min by a contact probe with electric resistance measuring device. precision of the measurement was ±1 cm

  11. A multi-channel magnetic induction tomography measurement system for human brain model imaging

    International Nuclear Information System (INIS)

    Xu, Zheng; Luo, Haijun; He, Wei; He, Chuanhong; Song, Xiaodong; Zahng, Zhanglong

    2009-01-01

    This paper proposes a multi-channel magnetic induction tomography measurement system for biological conductivity imaging in a human brain model. A hemispherical glass bowl filled with a salt solution is used as the human brain model; meanwhile, agar blocks of different conductivity are placed in the solution to simulate the intracerebral hemorrhage. The excitation and detection coils are fixed co-axially, and the axial gradiometer is used as the detection coil in order to cancel the primary field. On the outer surface of the glass bowl, 15 sensor units are arrayed in two circles as measurement parts, and a single sensor unit for canceling the phase drift is placed beside the glass bowl. The phase sensitivity of our system is 0.204°/S m −1 with the excitation frequency of 120 kHz and the phase noise is in the range of −0.03° to +0.05°. Only the coaxial detection coil is available for each excitation coil; therefore, 15 phase data are collected in each measurement turn. Finally, the two-dimensional images of conductivity distribution are obtained using an interpolation algorithm. The frequency-varying experiment indicates that the imaging quality becomes better as the excitation frequency is increased

  12. Interpretation of electrokinetic measurements with porous films: role of electric conductance and streaming current within porous structure.

    Science.gov (United States)

    Yaroshchuk, Andriy; Luxbacher, Thomas

    2010-07-06

    It is shown that in tangential electrokinetic measurements with porous films the porous structure makes contribution not only to the cell electric conductance (as demonstrated previously) but also to the observed streaming current. Both of these contributions give rise to dependences of streaming-potential and streaming-current coefficients on the channel height. However, due to the combined contribution of two phenomena, the dependence of streaming-potential coefficient on the channel height may be rather complicated and not allow for simple extrapolation. At the same time, the dependences of streaming-current coefficient and cell electric conductance on the channel height turn out linear and can be easily extrapolated to zero channel heights. This enables one to determine separately the contributions of external surface of porous film and of its porous structure to the streaming current and of the channel and porous structure to the cell electric conductance. This procedure is illustrated by the measurements of tangential electrokinetic phenomena and electric conductance with Millipore mixed-cellulose membrane filters of various average pore sizes (from 0.025 to 5 mum) in the so-called adjustable-gap cell of SurPASS electrokinetic instrument (Anton Paar GmbH). The design of this cell allows for easy and quasi-continuous variation of channel height as well as accurate determination of cell electric conductance, streaming-current coefficient, and channel height (from the cell hydraulic permeability). The quality of linear fits of experimental data has been found to be very good, and thus, the extrapolation procedures were quite reliable and accurate. Zeta-potentials could be determined of both external film and internal pore surfaces. It is demonstrated that the porous structures make considerable contributions to both streaming-current coefficient and cell electric conductance especially in the case of filters with larger pores. It is also found that, rather

  13. Electrochemical Investigations of the Interface at Li/Li+ Ion Conducting Channel

    Science.gov (United States)

    2006-10-04

    range of applications.1 Presently, these molecules are of particular interest in non-linear optics, as liquid crystals, as Langmuir - Blodgett films, for...cathode material in non-aqueous liquid electrolyte medium Since Li2Pc is a mixed ionic and electronic conductor, and some metal phthalocyanines are...14. ABSTRACT Dilithium phthalocyanine (Li2Pc) possesses mixed electronic- ionic conductivity due to overlap of - orbitals (electronic

  14. Coassembly of big conductance Ca2+-activated K+ channels and L-type voltage-gated Ca2+ channels in rat brain

    DEFF Research Database (Denmark)

    Grunnet, Morten; Kaufmann, Walter A

    2004-01-01

    Based on electrophysiological studies, Ca(2+)-activated K(+) channels and voltage-gated Ca(2+) channels appear to be located in close proximity in neurons. Such colocalization would ensure selective and rapid activation of K(+) channels by local increases in the cytosolic calcium concentration...

  15. A novel thick-film electrical conductivity sensor suitable for liquid and soil conductivity measurements

    OpenAIRE

    Atkinson, John; Sophocleous, Marios

    2015-01-01

    Results are reported from an initial evaluation of a novel conductivity sensor that could be incorporated onto a multi-element thick film (screen printed) sensor array designed for soil and water analysis. The new sensor exhibits a repeatable cell constant over a wide range of conductivities and is currently performing very well in an investigation of soil structural properties where its output is being correlated with soil water content in a study of different soil porosities.

  16. Measuring oxygen surface exchange kinetics on mixed-conducting composites by electrical conductivity relaxation

    NARCIS (Netherlands)

    Hu, Bobing; Wang, Yunlong; Zhu, Zhuoying; Xia, Changrong; Bouwmeester, Henricus J.M.

    2015-01-01

    The oxygen release kinetics of mixed-conducting Sr2Fe1.5Mo0.5O6 d–Sm0.2Ce0.8O2 d (SFM–SDC) dualphase composites has been investigated, at 750 C, as a function of the SDC phase volume fraction using electrical conductivity relaxation (ECR) under reducing atmospheres, extending our previous work on

  17. Regional two-dimensional magnetotelluric profile in West Bohemia/Vogtland reveals deep conductive channel into the earthquake swarm region

    Science.gov (United States)

    Muñoz, Gerard; Weckmann, Ute; Pek, Josef; Kováčiková, Světlana; Klanica, Radek

    2018-03-01

    The West Bohemia/Vogtland region, characterized by the intersection of the Eger (Ohře) Rift and the Mariánské Lázně fault, is a geodynamically active area exhibiting repeated occurrence of earthquake swarms, massive CO2 emanations and mid Pleistocene volcanism. The Eger Rift is the only known intra-continental region in Europe where such deep seated, active lithospheric processes currently take place. We present an image of electrical resistivity obtained from two-dimensional inversion of magnetotelluric (MT) data acquired along a regional profile crossing the Eger Rift. At the near surface, the Cheb basin and the aquifer feeding the mofette fields of Bublák and Hartoušov have been imaged as part of a region of very low resistivity. The most striking resistivity feature, however, is a deep reaching conductive channel which extends from the surface into the lower crust spatially correlated with the hypocentres of the seismic events of the Nový Kostel Focal Zone. This channel has been interpreted as imaging a pathway from a possible mid-crustal fluid reservoir to the surface. The resistivity model reinforces the relation between the fluid circulation along deep-reaching faults and the generation of the earthquakes. Additionally, a further conductive channel has been revealed to the south of the profile. This other feature could be associated to fossil hydrothermal alteration related to Mýtina and/or Neualbenreuth Maar structures or alternatively could be the signature of a structure associated to the suture between the Saxo-Thuringian and Teplá-Barrandian zones, whose surface expression is located only a few kilometres away.

  18. Imbalance of the liquid-metal flow and heat extraction in a manifold with sub-channels having locally different eletric conductivity

    International Nuclear Information System (INIS)

    Luo, Yang; Wen, Meimei; Kim, Chang Nyung; Yang, Shangjing

    2017-01-01

    In this study, the characteristics of liquid metal (LM) magnetohydrodynamic (MHD) flow and convective heat transfer in a manifold with three sub-channels having locally different electric conductivity are investigated with the use of commercial code CFX, allowing an imbalance in flow rate among the sub-channels, which can be used for intensive cooling of the region with higher heat load in the blanket. In a manifold with co-flow multiple sub-channels, the electrical current can cross the fluid regions and channel walls, thus influencing the flow distribution in each sub-channel. In the present study, cases with various arrangements of the electric conductivity in different parts of the channel walls are investigated, yielding different distributions of the current and fluid flow in different cases. Here, the mechanism governing the imbalance in mass flow rate among the sub-channels is discussed. The interdependency of the fluid velocity, current and electric potential of LM MHD flows in the three sub-channels are analyzed in detail. The results show that, in the sub-channel surrounded by the walls with lower electric conductivity, higher axial velocity and superior heat extraction can be obtained, with an effective cooling associated with higher velocity, where the higher velocity is closely related to the distribution of the electromotive component of the current in the flow field.

  19. Imbalance of the liquid-metal flow and heat extraction in a manifold with sub-channels having locally different eletric conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yang; Wen, Meimei [Department of Mechanical Engineering, Graduate School, Kyung Hee University, Yong-in, Kyunggi-do, 446-701 (Korea, Republic of); Kim, Chang Nyung, E-mail: cnkim@khu.ac.kr [Department of Mechanical Engineering, College of Engineering, Kyung Hee University, Yong-in, Kyunggi-do, 446-701 (Korea, Republic of); Yang, Shangjing [Department of Mechanical Engineering, Graduate School, Kyung Hee University, Yong-in, Kyunggi-do, 446-701 (Korea, Republic of)

    2017-04-15

    In this study, the characteristics of liquid metal (LM) magnetohydrodynamic (MHD) flow and convective heat transfer in a manifold with three sub-channels having locally different electric conductivity are investigated with the use of commercial code CFX, allowing an imbalance in flow rate among the sub-channels, which can be used for intensive cooling of the region with higher heat load in the blanket. In a manifold with co-flow multiple sub-channels, the electrical current can cross the fluid regions and channel walls, thus influencing the flow distribution in each sub-channel. In the present study, cases with various arrangements of the electric conductivity in different parts of the channel walls are investigated, yielding different distributions of the current and fluid flow in different cases. Here, the mechanism governing the imbalance in mass flow rate among the sub-channels is discussed. The interdependency of the fluid velocity, current and electric potential of LM MHD flows in the three sub-channels are analyzed in detail. The results show that, in the sub-channel surrounded by the walls with lower electric conductivity, higher axial velocity and superior heat extraction can be obtained, with an effective cooling associated with higher velocity, where the higher velocity is closely related to the distribution of the electromotive component of the current in the flow field.

  20. PIV Measurements of Turbulent Flow in a Channel with Solid or Perforated Ribs

    DEFF Research Database (Denmark)

    Wang, Lei; Salewski, Mirko; Sundén, Bengt

    2011-01-01

    Particle image velocimetry measurements are performed in a channel with periodic ribs on one wall. We investigate the flow around two different rib configurations: solid and perforated ribs with a slit. The ribs obstruct the channel by 20% of its height and are arranged 10 rib heights apart. For ...

  1. The Measurement of Thermal Conductivities of Silica and Carbon Black Powders at Different pressures by Thermal COnductivity Probe

    Institute of Scientific and Technical Information of China (English)

    X.G.Liang; X.S.Ge; 等

    1992-01-01

    This investigation was done to study the gas filled powder insulation and thermal conductivity probe for the measurent of thermal conductivity of powders.The mathematical analysis showed that the heat capacity of the probe itself and the thermal rsistance between the probe and powder must be considered .The authors developed a slender probe and measured the effective thermal conductivity of sillca and carbon black powders under a variety of conditions.

  2. Interpreting equilibrium-conductivity and conductivity-relaxation measurements to establish thermodynamic and transport properties for multiple charged defect conducting ceramics.

    Science.gov (United States)

    Zhu, Huayang; Ricote, Sandrine; Coors, W Grover; Kee, Robert J

    2015-01-01

    A model-based interpretation of measured equilibrium conductivity and conductivity relaxation is developed to establish thermodynamic, transport, and kinetics parameters for multiple charged defect conducting (MCDC) ceramic materials. The present study focuses on 10% yttrium-doped barium zirconate (BZY10). In principle, using the Nernst-Einstein relationship, equilibrium conductivity measurements are sufficient to establish thermodynamic and transport properties. However, in practice it is difficult to establish unique sets of properties using equilibrium conductivity alone. Combining equilibrium and conductivity-relaxation measurements serves to significantly improve the quantitative fidelity of the derived material properties. The models are developed using a Nernst-Planck-Poisson (NPP) formulation, which enables the quantitative representation of conductivity relaxations caused by very large changes in oxygen partial pressure.

  3. Small and intermediate conductance Ca2+-activated K+ channels confer distinctive patterns of distribution in human tissues and differential cellular localisation in the colon and corpus cavernosum

    NARCIS (Netherlands)

    Chen, Mao Xiang; Gorman, Shelby A.; Benson, Bill; Singh, Kuljit; Hieble, J. Paul; Michel, Martin C.; Tate, Simon N.; Trezise, Derek J.

    2004-01-01

    The SK/IK family of small and intermediate conductance calcium-activated potassium channels contains four members, SK1, SK2, SK3 and IK1, and is important for the regulation of a variety of neuronal and non-neuronal functions. In this study we have analysed the distribution of these channels in

  4. Antiarrhythmic effect of either negative modulation or blockade of small conductance Ca2+ activated K+ channels on ventricular fibrillation in guinea pig Langendorff perfused heart

    DEFF Research Database (Denmark)

    Diness, Jonas Goldin; Kirchhoff, Jeppe Egedal; Sheykhzade, Majid

    2015-01-01

    During recent years small conductance Ca activated K (SK) channels have been reported to play a role in cardiac electrophysiology. SK channels seem to be expressed in atria and ventricles but from a functional perspective atrial activity is predominant. A general notion seems to be that cardiac S...

  5. Localization of large conductance calcium-activated potassium channels and their effect on calcitonin gene-related peptide release in the rat trigemino-neuronal pathway

    DEFF Research Database (Denmark)

    Wulf-Johansson, H.; Amrutkar, D.V.; Hay-Schmidt, Anders

    2010-01-01

    Large conductance calcium-activated potassium (BK(Ca)) channels are membrane proteins contributing to electrical propagation through neurons. Calcitonin gene-related peptide (CGRP) is a neuropeptide found in the trigeminovascular system (TGVS). Both BK(Ca) channels and CGRP are involved in migrai...

  6. Homogeneous distribution of large-conductance calcium-dependent potassium channels on soma and apical dendrite of rat neocortical layer 5 pyramidal neurons.

    Science.gov (United States)

    Benhassine, Narimane; Berger, Thomas

    2005-02-01

    Voltage-gated conductances on dendrites of layer 5 pyramidal neurons participate in synaptic integration and output generation. We investigated the properties and the distribution of large-conductance calcium-activated potassium channels (BK channels) in this cell type using excised patches in acute slice preparations of rat somatosensory cortex. BK channels were characterized by their large conductance and sensitivity to the specific blockers paxilline and iberiotoxin. BK channels showed a pronounced calcium-dependence with a maximal opening probability of 0.69 at 10 microm and 0.42 at 3 microm free calcium. Their opening probability and transition time constants between open and closed states are voltage-dependent. At depolarized potentials, BK channel gating is described by two open and one closed states. Depolarization increases the opening probability due to a prolongation of the open time constant and a shortening of the closed time constant. Calcium-dependence and biophysical properties of somatic and dendritic BK channels were identical. The presence of BK channels on the apical dendrite of layer 5 pyramidal neurons was shown by immunofluorescence. Patch-clamp recordings revealed a homogeneous density of BK channels on the soma and along the apical dendrite up to 850 microm with a mean density of 1.9 channels per microm(2). BK channels are expressed either isolated or in clusters containing up to four channels. This study shows the presence of BK channels on dendrites. Their activation might modulate the shape of sodium and calcium action potentials, their propagation along the dendrite, and thereby the electrotonic distance between the somatic and dendritic action potential initiation zones.

  7. High-gradient normal-conducting RF structures for muon cooling channels

    International Nuclear Information System (INIS)

    Corlett, J.N.; Green, M.A.; Hartman, N.; Ladran, A.; Li, D.; MacGill, R.; Rimmer, R.; Moretti, A.; Jurgens, T.; Holtkamp, N.; Black, E.; Summers, D.; Booke, M.

    2001-01-01

    We present a status report on the research and development of high-gradient normal-conducting RF structures for the ionization cooling of muons in a neutrino factory or muon collider. High-gradient RF structures are required in regions enclosed in strong focusing solenoidal magnets, precluding the application of superconducting RF technology [1]. We propose using linear accelerating structures, with individual cells electromagnetically isolated, to achieve the required gradients of over 15 MV/m at 201 MHz and 30 MV/m at 805 MHz. Each cell will be powered independently, and cell length and drive phase adjusted to optimize shunt impedance of the assembled structure. This efficient design allows for relatively small field enhancement on the structure walls, and an accelerating field approximately 1.7 times greater than the peak surface field. The electromagnetic boundary of each cell may be provided by a thin Be sheet, or an assembly of thin-walled metal tubes. Use of thin, low-Z materials will allow passage of the muon beams without significant deterioration in beam quality due to scattering. R and D in design and analysis of robust structures that will operate under large electric and magnetic fields and RF current heating are discussed, including the experimental program based in a high-power test laboratory developed for this purpose

  8. Measurement of single top production in the tW channel and search for s channel in pp collisions

    CERN Document Server

    Merola, Mario

    2015-01-01

    Measurements of single top quark production in the tW and s channels in pp collisions are presented, based on data collected in 2012 at a centre-of-mass energy of 8 TeV. In the tW channel a top quark is produced in association with a W boson. The experimental signature is similar to top pair production, and there is interference at higher orders between the two processes. The measurement is perfomed using final states in which the associated W boson as well as the one originating from the top quark decay leptonically. Multivariate methods are used to extract the cross section and the result is compared with current standard model theory predictions. Multivariatetechniques are also adopted in the search for s-channel single top quark production inorder to discriminate the very small signal from the huge contribution of background processes. In both analyses the signal contribution is determined together with the background estimation by performing a maximum-likelihood fit to the Boosted Decision Trees discrimi...

  9. Measurement of damage profile in crystals by channeling technique

    International Nuclear Information System (INIS)

    Borovik, A.S.; Shipatov, E.T.

    1984-01-01

    A method of calculation of the random fraction Xsub(R)(l) in a disordered channel containing host and foreign atoms is described. According to this method dechaneling caused by single scattering as well as multiple scattering at defects is calculated taking into account positions of the self-interstitials and foreign atoms with respect to the lattice rows. The results demonstrate that the transverse energy distribution, flux peaking and, hence, Xsub(R)(l) and depth profiles of defects c(l) depend drastically on the defect position, concentration of implanted atoms, their position and the rechanneling process. The method is applied to experimental data for GaAs irradiated by He + and N-implanted Si. The obtained Xsub(R)(l) and c(l) are compared with those obtained using other methods. (author)

  10. Measuring neuroleptic-induced akathisia by three-channel actometry.

    Science.gov (United States)

    Tuisku, K; Lauerma, H; Holi, M; Markkula, J; Rimon, R

    1999-11-30

    Three-channel actometry was used to study neuroleptic-induced akathisia (NIA), a common and often serious disorder in association of traditional neuroleptic therapy. The aim was to explore the diagnostic possibilities of actometry in NIA and to examine in detail the motor phenomenology of the disorder in detail. The actometers were attached to the ankles and waists of ten patients, suffering from NIA, and to ten matched healthy controls. Five of the patients were changed to olanzapine treatment, and these patients were re-examined during the no-NIA condition. NIA was associated with manyfold movement activity during controlled rest (sitting) but not with increased daily overall motor activity. Movement frequencies in NIA seemed to be pathognomonic. Actometry is promising for investigation and clinical assessment of NIA. Olanzapine proved to be an adequate treatment choice for NIA patients.

  11. MiRNA-135a regulates the expression of small conductance calcium-activated potassium (SK3) channels in epilepsy-like conditions

    NARCIS (Netherlands)

    Honrath, Birgit; Norwood, Braxton; Tanrioever, Gaye; Kuter, Katarzyna; Henshall, David C; Aksel-Aksoy, Ayla; Schratt, Gerhard; Pasterkamp, Jeroen; Dencher, Norbert A.; Nieweg, Katja; Culmsee, Carsten; Dolga, Amalia Mihalea

    2017-01-01

    Background Excessive and hypersynchronous neuronal discharges are key characteristics in the pathophysiology of neurological disorders such as epilepsy. Owing to their ability of regulating neuronal excitability, small conductance calcium-activated potassium (SK) channels have been implicated in

  12. Measurement of thermal conductivity and diffusivity in situ: Literature survey and theoretical modelling of measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kukkonen, I.; Suppala, I. [Geological Survey of Finland, Espoo (Finland)

    1999-01-01

    In situ measurements of thermal conductivity and diffusivity of bedrock were investigated with the aid of a literature survey and theoretical simulations of a measurement system. According to the surveyed literature, in situ methods can be divided into `active` drill hole methods, and `passive` indirect methods utilizing other drill hole measurements together with cutting samples and petrophysical relationships. The most common active drill hole method is a cylindrical heat producing probe whose temperature is registered as a function of time. The temperature response can be calculated and interpreted with the aid of analytical solutions of the cylindrical heat conduction equation, particularly the solution for an infinite perfectly conducting cylindrical probe in a homogeneous medium, and the solution for a line source of heat in a medium. Using both forward and inverse modellings, a theoretical measurement system was analysed with an aim at finding the basic parameters for construction of a practical measurement system. The results indicate that thermal conductivity can be relatively well estimated with borehole measurements, whereas thermal diffusivity is much more sensitive to various disturbing factors, such as thermal contact resistance and variations in probe parameters. In addition, the three-dimensional conduction effects were investigated to find out the magnitude of axial `leak` of heat in long-duration experiments. The radius of influence of a drill hole measurement is mainly dependent on the duration of the experiment. Assuming typical conductivity and diffusivity values of crystalline rocks, the measurement yields information within less than a metre from the drill hole, when the experiment lasts about 24 hours. We propose the following factors to be taken as basic parameters in the construction of a practical measurement system: the probe length 1.5-2 m, heating power 5-20 Wm{sup -1}, temperature recording with 5-7 sensors placed along the probe, and

  13. Measurement of thermal conductivity and diffusivity in situ: Literature survey and theoretical modelling of measurements

    International Nuclear Information System (INIS)

    Kukkonen, I.; Suppala, I.

    1999-01-01

    In situ measurements of thermal conductivity and diffusivity of bedrock were investigated with the aid of a literature survey and theoretical simulations of a measurement system. According to the surveyed literature, in situ methods can be divided into 'active' drill hole methods, and 'passive' indirect methods utilizing other drill hole measurements together with cutting samples and petrophysical relationships. The most common active drill hole method is a cylindrical heat producing probe whose temperature is registered as a function of time. The temperature response can be calculated and interpreted with the aid of analytical solutions of the cylindrical heat conduction equation, particularly the solution for an infinite perfectly conducting cylindrical probe in a homogeneous medium, and the solution for a line source of heat in a medium. Using both forward and inverse modellings, a theoretical measurement system was analysed with an aim at finding the basic parameters for construction of a practical measurement system. The results indicate that thermal conductivity can be relatively well estimated with borehole measurements, whereas thermal diffusivity is much more sensitive to various disturbing factors, such as thermal contact resistance and variations in probe parameters. In addition, the three-dimensional conduction effects were investigated to find out the magnitude of axial 'leak' of heat in long-duration experiments. The radius of influence of a drill hole measurement is mainly dependent on the duration of the experiment. Assuming typical conductivity and diffusivity values of crystalline rocks, the measurement yields information within less than a metre from the drill hole, when the experiment lasts about 24 hours. We propose the following factors to be taken as basic parameters in the construction of a practical measurement system: the probe length 1.5-2 m, heating power 5-20 Wm -1 , temperature recording with 5-7 sensors placed along the probe, and

  14. Research on measurement of neutron flux in irradiation channels of research reactor

    International Nuclear Information System (INIS)

    Yin Zhitao; Lv Zheng; Wang Yulin; Zheng Wuqin

    2014-01-01

    Relative distribution of thermal neutron flux in the irradiation channel is measured by classical activation foil method. After that, on a representative point in the irradiation channel, neutron temperature and absolute neutron flux are also measured. Cadmium ratio correction method is used to check the experiment result in the end. Comparative analysis shows that the results from two different methods are agreed pretty well, which adds the credibility of experiment results. (authors)

  15. Measurement of total dissolved solids using electrical conductivity

    International Nuclear Information System (INIS)

    Ray, Vinod K.; Jat, J.R.; Reddy, G.B.; Balaji Rao, Y.; Phani Babu, C.; Kalyanakrishnan, G.

    2017-01-01

    Total dissolved solids (TDS) is an important parameter for the disposal of effluents generated during processing of different raw materials like Magnesium Di-uranate (MDU), Heat Treated Uranium Peroxide (HTUP), Sodium Di-uranate (SDU) in Uranium Extraction plant and Washed and Dried Frit (WDF) in Zirconium Extraction Plant. The present paper describes the use of electrical conductivity for determination of TDS. As electrical conductivity is matrix dependent property, matrix matched standards were prepared for determination of TDS in ammonium nitrate solution (AN) and mixture of ammonium nitrate and ammonium sulphate (AN/AS) and results were found to be in good agreement when compared with evaporation method. (author)

  16. External K+ dependence of strong inward rectifier K+ channel conductance is caused not by K+ but by competitive pore blockade by external Na.

    Science.gov (United States)

    Ishihara, Keiko

    2018-06-15

    Strong inward rectifier K + (sKir) channels determine the membrane potentials of many types of excitable and nonexcitable cells, most notably the resting potentials of cardiac myocytes. They show little outward current during membrane depolarization (i.e., strong inward rectification) because of the channel blockade by cytoplasmic polyamines, which depends on the deviation of the membrane potential from the K + equilibrium potential ( V - E K ) when the extracellular K + concentration ([K + ] out ) is changed. Because their open - channel conductance is apparently proportional to the "square root" of [K + ] out , increases/decreases in [K + ] out enhance/diminish outward currents through sKir channels at membrane potentials near their reversal potential, which also affects, for example, the repolarization and action-potential duration of cardiac myocytes. Despite its importance, however, the mechanism underlying the [K + ] out dependence of the open sKir channel conductance has remained elusive. By studying Kir2.1, the canonical member of the sKir channel family, we first show that the outward currents of Kir2.1 are observed under the external K + -free condition when its inward rectification is reduced and that the complete inhibition of the currents at 0 [K + ] out results solely from pore blockade caused by the polyamines. Moreover, the noted square-root proportionality of the open sKir channel conductance to [K + ] out is mediated by the pore blockade by the external Na + , which is competitive with the external K + Our results show that external K + itself does not activate or facilitate K + permeation through the open sKir channel to mediate the apparent external K + dependence of its open channel conductance. The paradoxical increase/decrease in outward sKir channel currents during alternations in [K + ] out , which is physiologically relevant, is caused by competition from impermeant extracellular Na . © 2018 Ishihara.

  17. Co-channel and Adjacent Channel Interference Measurement of UMTS and GSM/EDGE Systems in 900 MHz Radio Band

    Directory of Open Access Journals (Sweden)

    S. Hanus

    2008-09-01

    Full Text Available This paper is concerned with inter-system and intra-system interference measurements of 2.5G and 3G mobile communication systems. The both systems UMTS and GSM/EDGE are assumed to operate in a common radio band of 900 MHz. The main system parameters are briefly introduced as well as the measurement scenario. Several simulations and key measurements were performed. Important results are described and commented along with a graphical representation, namely bit error ratio (BER dependence on carrier to noise ratio (CNR in the presence of additive white Gaussian noise (AWGN, the measurement of adjacent channel interference ratio of each system, the coexistence of both systems in same band and the impact of a carrier offset on BER.

  18. The role of water channel proteins in facilitating recovery of leaf hydraulic conductance from water stress in Populus trichocarpa.

    Directory of Open Access Journals (Sweden)

    Joan Laur

    Full Text Available Gas exchange is constrained by the whole-plant hydraulic conductance (Kplant. Leaves account for an important fraction of Kplant and may therefore represent a major determinant of plant productivity. Leaf hydraulic conductance (Kleaf decreases with increasing water stress, which is due to xylem embolism in leaf veins and/or the properties of the extra-xylary pathway. Water flow through living tissues is facilitated and regulated by water channel proteins called aquaporins (AQPs. Here we assessed changes in the hydraulic conductance of Populus trichocarpa leaves during a dehydration-rewatering episode. While leaves were highly sensitive to drought, Kleaf recovered only 2 hours after plants were rewatered. Recovery of Kleaf was absent when excised leaves were bench-dried and subsequently xylem-perfused with a solution containing AQP inhibitors. We examined the expression patterns of 12 highly expressed AQP genes during a dehydration-rehydration episode to identify isoforms that may be involved in leaf hydraulic adjustments. Among the AQPs tested, several genes encoding tonoplast intrinsic proteins (TIPs showed large increases in expression in rehydrated leaves, suggesting that TIPs contribute to reversing drought-induced reductions in Kleaf. TIPs were localized in xylem parenchyma, consistent with a role in facilitating water exchange between xylem vessels and adjacent living cells. Dye uptake experiments suggested that reversible embolism formation in minor leaf veins contributed to the observed changes in Kleaf.

  19. The role of water channel proteins in facilitating recovery of leaf hydraulic conductance from water stress in Populus trichocarpa.

    Science.gov (United States)

    Laur, Joan; Hacke, Uwe G

    2014-01-01

    Gas exchange is constrained by the whole-plant hydraulic conductance (Kplant). Leaves account for an important fraction of Kplant and may therefore represent a major determinant of plant productivity. Leaf hydraulic conductance (Kleaf) decreases with increasing water stress, which is due to xylem embolism in leaf veins and/or the properties of the extra-xylary pathway. Water flow through living tissues is facilitated and regulated by water channel proteins called aquaporins (AQPs). Here we assessed changes in the hydraulic conductance of Populus trichocarpa leaves during a dehydration-rewatering episode. While leaves were highly sensitive to drought, Kleaf recovered only 2 hours after plants were rewatered. Recovery of Kleaf was absent when excised leaves were bench-dried and subsequently xylem-perfused with a solution containing AQP inhibitors. We examined the expression patterns of 12 highly expressed AQP genes during a dehydration-rehydration episode to identify isoforms that may be involved in leaf hydraulic adjustments. Among the AQPs tested, several genes encoding tonoplast intrinsic proteins (TIPs) showed large increases in expression in rehydrated leaves, suggesting that TIPs contribute to reversing drought-induced reductions in Kleaf. TIPs were localized in xylem parenchyma, consistent with a role in facilitating water exchange between xylem vessels and adjacent living cells. Dye uptake experiments suggested that reversible embolism formation in minor leaf veins contributed to the observed changes in Kleaf.

  20. Direct measurement of the microscale conductivity of conjugated polymer monolayers

    DEFF Research Database (Denmark)

    Bøggild, Peter; Grey, Francois; Hassenkam, T.

    2000-01-01

    The in-plane conductivity of conjugated polymer monolayers is mapped here for the first time on the microscale using a novel scanning micro four-point probe (see Figure). The probe allows the source, drain, and voltage electrodes to be positioned within the same domain and the mapping results...

  1. A method of measuring the thermal conductivity of liquids

    NARCIS (Netherlands)

    Held, E.F.M. van der; Drunen, F.G. van

    1949-01-01

    We described the development of an apparatus for the determination of the thermal conductivity of liquids. The apparatus is suitable for all kinds of liquids, including the strongest acids. From a given time we pass an electric current through a thin straight wire, placed in a homogeneous material

  2. Electrical conductivity measurements on gel grown KDP crystals ...

    Indian Academy of Sciences (India)

    Impurity added KDP crystals; gel method; electrical conductivity; activation energy. 1. Introduction. Potassium dihydrogen ... phate [(NH4)2SO4] along with double distilled water and ethyl alcohol were used. KDP was added with .... in the vicinity of electrodes or chemical changes in layers close to electrodes (Bunget and ...

  3. 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%.

  4. Contactless measurement of alternating current conductance in quantum Hall structures

    Energy Technology Data Exchange (ETDEWEB)

    Drichko, I. L.; Diakonov, A. M.; Malysh, V. A.; Smirnov, I. Yu.; Ilyinskaya, N. D.; Usikova, A. A. [A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Galperin, Y. M. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo (Norway); A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Kummer, M.; Känel, H. von [Laboratorium für Festkörperphysik ETH Zürich, CH-8093 Zürich (Switzerland)

    2014-10-21

    We report a procedure to determine the frequency-dependent conductance of quantum Hall structures in a broad frequency domain. The procedure is based on the combination of two known probeless methods—acoustic spectroscopy and microwave spectroscopy. By using the acoustic spectroscopy, we study the low-frequency attenuation and phase shift of a surface acoustic wave in a piezoelectric crystal in the vicinity of the electron (hole) layer. The electronic contribution is resolved using its dependence on a transverse magnetic field. At high frequencies, we study the attenuation of an electromagnetic wave in a coplanar waveguide. To quantitatively calibrate these data, we use the fact that in the quantum-Hall-effect regime the conductance at the maxima of its magnetic field dependence is determined by extended states. Therefore, it should be frequency independent in a broad frequency domain. The procedure is verified by studies of a well-characterized p-SiGe/Ge/SiGe heterostructure.

  5. Measurement and Modelling of MIC Components Using Conductive Lithographic Films

    OpenAIRE

    Shepherd, P. R.; Taylor, C.; Evans l, P. S. A.; Harrison, D. J.

    2001-01-01

    Conductive Lithographic Films (CLFs) have previously demonstrated useful properties in printed mi-crowave circuits, combining low cost with high speed of manufacture. In this paper we examine the formation of various passive components via the CLF process, which enables further integration of printed microwave integrated circuits. The printed components include vias, resistors and overlay capacitors, and offer viable alternatives to traditional manufacturing processes for Microwave Inte-grate...

  6. Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons

    NARCIS (Netherlands)

    Battefeld, A.; Tran, B.T.; Gavrilis, J.; Cooper, E.C.; Kole, Maarten|info:eu-repo/dai/nl/256257574

    2014-01-01

    Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of Kv7 potassium channels and voltage-gated sodium (Nav ) channels in the axonal

  7. Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons

    NARCIS (Netherlands)

    Battefeld, A.; Tran, Baouyen T; Gavrilis, Jason; Cooper, Edward C; Kole, Maarten H P

    2014-01-01

    Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of K(v)7 potassium channels and voltage-gated sodium (Na(v)) channels in the

  8. Procedure to determine the two channel timing measurement accuracy and precision of a digital oscilloscope

    International Nuclear Information System (INIS)

    Johnson, M.; Matulik, M.

    1994-01-01

    The digital oscilloscope allows one to make numerous timing measurements, but just how good are those measurements? This document describes a procedure which can be used to determine the accuracy and precision to which a digital oscilloscope can make various two channel timing measurements

  9. Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures

    Science.gov (United States)

    Fesmire, James; Sass, Jared; Johnson, Wesley

    2010-01-01

    With the advance of polymer and other non-metallic material sciences, whole new series of polymeric materials and composites are being created. These materials are being optimized for many different applications including cryogenic and low-temperature industrial processes. Engineers need these data to perform detailed system designs and enable new design possibilities for improved control, reliability, and efficiency in specific applications. One main area of interest is cryogenic structural elements and fluid handling components and other parts, films, and coatings for low-temperature application. An important thermal property of these new materials is the apparent thermal conductivity (k-value).

  10. Nanoscale Electromechanics To Measure Thermal Conductivity, Expansion, and Interfacial Losses.

    Science.gov (United States)

    Mathew, John P; Patel, Raj; Borah, Abhinandan; Maliakkal, Carina B; Abhilash, T S; Deshmukh, Mandar M

    2015-11-11

    We study the effect of localized Joule heating on the mechanical properties of doubly clamped nanowires under tensile stress. Local heating results in systematic variation of the resonant frequency; these frequency changes result from thermal stresses that depend on temperature dependent thermal conductivity and expansion coefficient. The change in sign of the linear expansion coefficient of InAs is reflected in the resonant response of the system near a bath temperature of 20 K. Using finite element simulations to model the experimentally observed frequency shifts, we show that the thermal conductivity of a nanowire can be approximated in the 10-60 K temperature range by the empirical form κ = bT W/mK, where the value of b for a nanowire was found to be b = 0.035 W/mK(2), significantly lower than bulk values. Also, local heating allows us to independently vary the temperature of the nanowire relative to the clamping points pinned to the bath temperature. We suggest a loss mechanism (dissipation ~10(-4)-10(-5)) originating from the interfacial clamping losses between the metal and the semiconductor nanostructure.

  11. Induced convection cylindrical probe conductivity measurements on permeable media

    International Nuclear Information System (INIS)

    Fodemesi, S.P.; Beck, A.E.

    1983-01-01

    This chapter presents results from a program of investigation using the transient needle probe thermal conductivity technique on fluid saturated permeable media with a glass bead matrix. Uses eight additional radially located sensors in order to correlate the convection effects on the temperature sensor in the heater probe with convection behavior in the medium; all were scanned frequently with a data acquisition system, from the start of the experiment through a few hours of experimental time. Points out that with typical conditions encountered in oceanic heat flow work, induced convection may commence as early as 60 s from the start of the experiment. Finds that the convection effects are worse when the needle probe is oriented horizontally than when it is oriented vertically (gradients orthogonal to the gravitational field), and a correlation is made between permeability and the time of onset and the extent of convective effects. Indicates errors in conductivity as large as 40%. Suggests empirical techniques for detecting and correcting for thermal convection using probe sensor data alone

  12. Measurement of plasma conductivity using faraday rotation of submillimeter waves

    International Nuclear Information System (INIS)

    Kuzmenko, P.J.; Self, S.A.

    1983-01-01

    This paper examines the application of Faraday rotation to the measurement of electron combustion MHD plasmas. Details on the design of a working system are given, including the selection of operating wavelength. A theoretical comparison between the Faraday rotation technique and two-path interferometry shows Faraday rotation in its simplest form to be somewhat less sensitive to changes in electron concentration. This deficit can be balanced against greater immunity to vibration and thermal drift. Improved techniques of measuring the rotation angle promise greater sensitivity. A preliminary experiment has verified the technique

  13. Metrological Array of Cyber-Physical Systems. Part 11. Remote Error Correction of Measuring Channel

    Directory of Open Access Journals (Sweden)

    Yuriy YATSUK

    2015-09-01

    Full Text Available The multi-channel measuring instruments with both the classical structure and the isolated one is identified their errors major factors basing on general it metrological properties analysis. Limiting possibilities of the remote automatic method for additive and multiplicative errors correction of measuring instruments with help of code-control measures are studied. For on-site calibration of multi- channel measuring instruments, the portable voltage calibrators structures are suggested and their metrological properties while automatic errors adjusting are analysed. It was experimentally envisaged that unadjusted error value does not exceed ± 1 mV that satisfies most industrial applications. This has confirmed the main approval concerning the possibilities of remote errors self-adjustment as well multi- channel measuring instruments as calibration tools for proper verification.

  14. Measurements Conducted on an Unknown Object Labeled Pu-239

    International Nuclear Information System (INIS)

    Hoteling, Nathan

    2013-01-01

    Measurements were carried out on 12 November 2013 to determine whether Pu-239 was present on an object discovered in a plastic bag with label ''Pu-239 6 uCi''. Following initial survey measurements to verify that the object was not leaking or contaminated, spectra were collected with a High Purity Germanium (HPGe) detector with object positioned in two different configurations. Analysis of the spectra did not yield any direct evidence of Pu-239. From the measured spectra, minimum detectable activity (MDA) was determined to be approximately 2 uCi for the gamma ray measurements. Although there was no direct evidence of Pu-239, a peak at 60 keV characteristic of Am-241 decay was observed. Since it is very likely that Am-241 would be present in aged plutonium samples, this was interpreted as indirect evidence for the presence of plutonium on the object. Analysis of this peak led to an estimated Pu-239 activity of 0.02-0.04 uCi, or <1x10 -6 grams.

  15. Measuring Thermal Conductivity of a Small Insulation Sample

    Science.gov (United States)

    Miller, Robert A.; Kuczmarski, Maria A.

    2009-01-01

    A multiple-throat venturi system has been invented for measuring laminar flow of air or other gas at low speed (1 to 30 cm/s) in a duct while preserving the laminar nature of the flow and keeping the velocity profile across the duct as nearly flat as possible. While means for measuring flows at higher speeds are well established, heretofore, there have been no reliable means for making consistent, accurate measurements in this speed range. In the original application for which this system was invented, the duct leads into the test section of a low-speed wind tunnel wherein uniform, low-speed, laminar flow is required for scientific experiments. The system could also be used to monitor a slow flow of gas in an industrial process like chemical vapor deposition. In the original application, the multiple- throat venturi system is mounted at the inlet end of the duct having a rectangular cross section of 19 by 14 cm, just upstream of an assembly of inlet screens and flow straighteners that help to suppress undesired flow fluctuations (see Figure 1). The basic venturi measurement principle is well established: One measures the difference in pressure between (1) a point just outside the inlet, where the pressure is highest and the kinetic energy lowest; and (2) the narrowest part (the throat) of the venturi passage, where the kinetic energy is highest and the pressure is lowest. Then by use of Bernoulli s equation for the relationship between pressure and kinetic energy, the volumetric flow speed in the duct can be calculated from the pressure difference and the inlet and throat widths. The design of this system represents a compromise among length, pressure recovery, uniformity of flow, and complexity of assembly. Traditionally, venturis are used to measure faster flows in narrower cross sections, with longer upstream and downstream passages to maintain accuracy. The dimensions of the passages of the present venturi system are sized to provide a readily measurable

  16. Measurement of the Top Quark Mass Simultaneously in Dilepton and Lepton + Jets Decay Channels

    Energy Technology Data Exchange (ETDEWEB)

    Fedorko, Wojciech T. [Univ. of Chicago, IL (United States)

    2008-12-01

    The authors present the first measurement of the top quark mass using simultaneously data from two decay channels. They use a data sample of √s = 1.96 TeV collisions with integrated luminosity of 1.9 fb-1 collected by the CDF II detector. They select dilepton and lepton + jets channel decays of t$\\bar{t}$ pairs and reconstruct two observables in each topology. They use non-parametric techniques to derive probability density functions from simulated signal and background samples. The observables are the reconstructed top quark mass and the scalar sum of transverse energy of the event in the dilepton topology and the reconstructed top quark mass and the invariant mass of jets from the W boson decay in lepton + jets channel. They perform a simultaneous fit for the top quark mass and the jet energy scale which is constrained in situ by the hadronic W boson resonance from the lepton + jets channel. Using 144 dilepton candidate events and 332 lepton + jets candidate events they measure: Mtop = 171.9 ± 1.7 (stat. + JES) ± 1.1 (other sys.) GeV/c2 = 171.9 ± 2.0 GeV/c2. The measurement features a robust treatment of the systematic uncertainties, correlated between the two channels and develops techniques for a future top quark mass measurement simultaneously in all decay channels. Measurements of the W boson mass and the top quark mass provide a constraint on the mass of the yet unobserved Higgs boson. The Higgs boson mass implied by measurement presented here is higher than Higgs boson mass implied by previously published, most precise CDF measurements of the top quark mass in lepton + jets and dilepton channels separately.

  17. A New Top Mass Measurement in The Dilepton Channel

    Energy Technology Data Exchange (ETDEWEB)

    Trovato, Marco; /INFN, Pisa /Pisa U.

    2008-01-01

    The top quark discovery completed the present picture of the fundamental constituents of the nature. Since then, the Collider Detector at Fermilab and D0 Collaborations have been spending great efforts to measure its properties better. About 30 times larger than the second heaviest quark, the mass of the top has been measured with increased statistic and more and more sophisticated techniques in order to reduce as much as possible its uncertainty. This is because the top is expected to play a fundamental role in the Standard Model. The value of its mass sets boundaries on the mass of the unobserved Higgs boson, and perhaps more appealing, studies of its properties might lead to the discovery of new physics.

  18. Integrated optical measurement system for fluorescence spectroscopy in microfluidic channels

    DEFF Research Database (Denmark)

    Hübner, Jörg; Mogensen, Klaus Bo; Jørgensen, Anders Michael

    2001-01-01

    A transportable miniaturized fiber-pigtailed measurement system is presented which allows quantitative fluorescence detection in microliquid handling systems. The microliquid handling chips are made in silica on silicon technology and the optical functionality is monolithically integrated with th...... with two dyes, fluorescein, and Bodipy 650/665 X, showed good linear behavior over a wide range of concentrations. Minimally detected concentrations were 250 pM for fluorescein and 100 nM for Bodipy....

  19. First results from car-to-car and car-to-infrastructure radio channel measurements at 5.2GHZ

    OpenAIRE

    Paier, Alexander; Kåredal, Johan; Czink, Nicolai; Hofstetter, Helmut; Dumard, Charlotte; Zemen, Thomas; Tufvesson, Fredrik; Mecklenbräuker, Christoph; Molisch, Andreas

    2007-01-01

    Car-to-car and car-to-infrastructure (henceforth called C2X) communications are constantly gaining importance for road-safety and other applications. In order to design efficient C2X systems, an understanding of realistic C2X propagation channels is required, but currently, only few measurements have been published. This paper presents a description of an extensive measurement campaign recently conducted in an urban scenario, a rural scenario, and on a highway. We focused on 4 ÿ 4 multiple-in...

  20. Measurement of a Conduction Cooled Nb3Sn Racetrack Coil

    Science.gov (United States)

    Kim, HS; Kovacs, C.; Rochester, J.; Sumption, MD; Tomsic, M.; Peng, X.; Doll, D.

    2017-12-01

    Use of superconducting coils for wind turbines and electric aircraft is of interest because of the potential for high power density and weight reduction. Here we test a racetrack coil developed as a proof-of-concept for cryogen-free superconducting motors and generators. The coil was wound with 1209 m of 0.7-mm-diameter insulated tube-type Nb3Sn wire. The coil was epoxy-impregnated, instrumented, covered with numerous layers of aluminized mylar insulation, and inserted vertically into a dewar. The system was cooled to 4.2 K, and a few inches of liquid helium was allowed to collect at the bottom of the dewar but below the coil. The coil was cooled by conduction via copper cooling bars were attached to the coil but also were immersed in the liquid helium at their lower ends. Several current tests were performed on the coil, initially in voltage mode, and one run in current mode. The maximum coil Ic at 4.2 K was 480 A, generating 3.06 T at the surface of the coil. The coil met the design targets with a noticeable margin.

  1. Interplay between Appearance and Disappearance Channels for Precision Measurements of θ₂₃ and δ

    Energy Technology Data Exchange (ETDEWEB)

    Coloma, Pilar; Minakata, Hisakazu; Parke, Stephen J.

    2014-11-01

    We discuss how the CP violating phase δ and the mixing angle θ₂₃ can be measured precisely in an environment where there are strong correlations between them. This is achieved by paying special attention to the mutual roles and the interplay between the appearance and the disappearance channels in long-baseline neutrino oscillation experiments. We analyze and clarify the general structure of the θ₂₃ - θ₁₃ - δ degeneracy for both the appearance and disappearance channels in a more complete fashion than what has previously been discussed in the literature. A full understanding of this degeneracy is of vital importance if θ₂₃ is close to maximal mixing. The relative importance between the appearance and disappearance channels depends upon the particular setup and how close to maximal mixing Nature has chosen the value for θ₂₃. For facilities that operate with a narrow band beam or a wide band beam centered on the first oscillation extremum, the contribution of the disappearance channel depends critically on the systematic uncertainties assumed for this channel. Whereas for facilities that operate at energies above the first oscillation extremum or at the second oscillation extremum the appearance channels dominate. On the other hand, for δ we find that the disappearance channel usually improves the sensitivity, modestly for facilities around the first oscillation extremum and more significantly for facilities operating at an energy above the first oscillation extremum, especially near δ ~ ± π/2.

  2. Four-channel high speed synchronized acquisition multiple trigger storage measurement system

    International Nuclear Information System (INIS)

    Guo Jian; Wang Wenlian; Zhang Zhijie

    2010-01-01

    A new storage measurement system based on the CPLD, MCU and FLASH (large-capacity flash memory) is proposed. The large capacity storage characteristic of the FLASH MEMORY is used to realize multi channel synchronized acquisition and the function of multiple records and read once. The function of multi channel synchronization, high speed data acquisition, the triggering several times, and the adjustability of working parameters expands the application of storage measurement system. The storage measurement system can be used in a variety of pressure and temperature test in explosion field. (authors)

  3. Noninvasive electrical conductivity measurement by MRI: a test of its validity and the electrical conductivity characteristics of glioma.

    Science.gov (United States)

    Tha, Khin Khin; Katscher, Ulrich; Yamaguchi, Shigeru; Stehning, Christian; Terasaka, Shunsuke; Fujima, Noriyuki; Kudo, Kohsuke; Kazumata, Ken; Yamamoto, Toru; Van Cauteren, Marc; Shirato, Hiroki

    2018-01-01

    This study noninvasively examined the electrical conductivity (σ) characteristics of diffuse gliomas using MRI and tested its validity. MRI including a 3D steady-state free precession (3D SSFP) sequence was performed on 30 glioma patients. The σ maps were reconstructed from the phase images of the 3D SSFP sequence. The σ histogram metrics were extracted and compared among the contrast-enhanced (CET) and noncontrast-enhanced tumour components (NCET) and normal brain parenchyma (NP). Difference in tumour σ histogram metrics among tumour grades and correlation of σ metrics with tumour grades were tested. Validity of σ measurement using this technique was tested by correlating the mean tumour σ values measured using MRI with those measured ex vivo using a dielectric probe. Several σ histogram metrics of CET and NCET of diffuse gliomas were significantly higher than NP (Bonferroni-corrected p ≤ .045). The maximum σ of NCET showed a moderate positive correlation with tumour grade (r = .571, Bonferroni-corrected p = .018). The mean tumour σ measured using MRI showed a moderate positive correlation with the σ measured ex vivo (r = .518, p = .040). Tissue σ can be evaluated using MRI, incorporation of which may better characterise diffuse gliomas. • This study tested the validity of noninvasive electrical conductivity measurements by MRI. • This study also evaluated the electrical conductivity characteristics of diffuse glioma. • Gliomas have higher electrical conductivity values than the normal brain parenchyma. • Noninvasive electrical conductivity measurement can be helpful for better characterisation of glioma.

  4. Effect of weak measurement on entanglement distribution over noisy channels.

    Science.gov (United States)

    Wang, Xin-Wen; Yu, Sixia; Zhang, Deng-Yu; Oh, C H

    2016-03-03

    Being able to implement effective entanglement distribution in noisy environments is a key step towards practical quantum communication, and long-term efforts have been made on the development of it. Recently, it has been found that the null-result weak measurement (NRWM) can be used to enhance probabilistically the entanglement of a single copy of amplitude-damped entangled state. This paper investigates remote distributions of bipartite and multipartite entangled states in the amplitudedamping environment by combining NRWMs and entanglement distillation protocols (EDPs). We show that the NRWM has no positive effect on the distribution of bipartite maximally entangled states and multipartite Greenberger-Horne-Zeilinger states, although it is able to increase the amount of entanglement of each source state (noisy entangled state) of EDPs with a certain probability. However, we find that the NRWM would contribute to remote distributions of multipartite W states. We demonstrate that the NRWM can not only reduce the fidelity thresholds for distillability of decohered W states, but also raise the distillation efficiencies of W states. Our results suggest a new idea for quantifying the ability of a local filtering operation in protecting entanglement from decoherence.

  5. Contribution of small conductance K+ channels to sinoatrial node pacemaker activity: insights from atrial-specific Na+ /Ca2+ exchange knockout mice.

    Science.gov (United States)

    Torrente, Angelo G; Zhang, Rui; Wang, Heidi; Zaini, Audrey; Kim, Brian; Yue, Xin; Philipson, Kenneth D; Goldhaber, Joshua I

    2017-06-15

    Repolarizing currents through K + channels are essential for proper sinoatrial node (SAN) pacemaking, but the influence of intracellular Ca 2+ on repolarization in the SAN is uncertain. We identified all three isoforms of Ca 2+ -activated small conductance K + (SK) channels in the murine SAN. SK channel blockade slows repolarization and subsequent depolarization of SAN cells. In the atrial-specific Na + /Ca 2+ exchanger (NCX) knockout mouse, cellular Ca 2+ accumulation during spontaneous SAN pacemaker activity produces intermittent hyperactivation of SK channels, leading to arrhythmic pauses alternating with bursts of pacing. These findings suggest that Ca 2+ -sensitive SK channels can translate changes in cellular Ca 2+ into a repolarizing current capable of modulating pacemaking. SK channels are a potential pharmacological target for modulating SAN rate or treating SAN dysfunction, particularly under conditions characterized by abnormal increases in diastolic Ca 2+ . Small conductance K + (SK) channels have been implicated as modulators of spontaneous depolarization and electrical conduction that may be involved in cardiac arrhythmia. However, neither their presence nor their contribution to sinoatrial node (SAN) pacemaker activity has been investigated. Using quantitative PCR (q-PCR), immunostaining and patch clamp recordings of membrane current and voltage, we identified all three SK isoforms (SK1, SK2 and SK3) in mouse SAN. Inhibition of SK channels with the specific blocker apamin prolonged action potentials (APs) in isolated SAN cells. Apamin also slowed diastolic depolarization and reduced pacemaker rate in isolated SAN cells and intact tissue. We investigated whether the Ca 2+ -sensitive nature of SK channels could explain arrhythmic SAN pacemaker activity in the atrial-specific Na + /Ca 2+ exchange (NCX) knockout (KO) mouse, a model of cellular Ca 2+ overload. SAN cells isolated from the NCX KO exhibited higher SK current than wildtype (WT) and apamin

  6. Analysis and compensation of synchronous measurement error for multi-channel laser interferometer

    International Nuclear Information System (INIS)

    Du, Shengwu; Hu, Jinchun; Zhu, Yu; Hu, Chuxiong

    2017-01-01

    Dual-frequency laser interferometer has been widely used in precision motion system as a displacement sensor, to achieve nanoscale positioning or synchronization accuracy. In a multi-channel laser interferometer synchronous measurement system, signal delays are different in the different channels, which will cause asynchronous measurement, and then lead to measurement error, synchronous measurement error (SME). Based on signal delay analysis of the measurement system, this paper presents a multi-channel SME framework for synchronous measurement, and establishes the model between SME and motion velocity. Further, a real-time compensation method for SME is proposed. This method has been verified in a self-developed laser interferometer signal processing board (SPB). The experiment result showed that, using this compensation method, at a motion velocity 0.89 m s −1 , the max SME between two measuring channels in the SPB is 1.1 nm. This method is more easily implemented and applied to engineering than the method of directly testing smaller signal delay. (paper)

  7. Analysis and compensation of synchronous measurement error for multi-channel laser interferometer

    Science.gov (United States)

    Du, Shengwu; Hu, Jinchun; Zhu, Yu; Hu, Chuxiong

    2017-05-01

    Dual-frequency laser interferometer has been widely used in precision motion system as a displacement sensor, to achieve nanoscale positioning or synchronization accuracy. In a multi-channel laser interferometer synchronous measurement system, signal delays are different in the different channels, which will cause asynchronous measurement, and then lead to measurement error, synchronous measurement error (SME). Based on signal delay analysis of the measurement system, this paper presents a multi-channel SME framework for synchronous measurement, and establishes the model between SME and motion velocity. Further, a real-time compensation method for SME is proposed. This method has been verified in a self-developed laser interferometer signal processing board (SPB). The experiment result showed that, using this compensation method, at a motion velocity 0.89 m s-1, the max SME between two measuring channels in the SPB is 1.1 nm. This method is more easily implemented and applied to engineering than the method of directly testing smaller signal delay.

  8. Rényi entropy measure of noise-aided information transmission in a binary channel.

    Science.gov (United States)

    Chapeau-Blondeau, François; Rousseau, David; Delahaies, Agnès

    2010-05-01

    This paper analyzes a binary channel by means of information measures based on the Rényi entropy. The analysis extends, and contains as a special case, the classic reference model of binary information transmission based on the Shannon entropy measure. The extended model is used to investigate further possibilities and properties of stochastic resonance or noise-aided information transmission. The results demonstrate that stochastic resonance occurs in the information channel and is registered by the Rényi entropy measures at any finite order, including the Shannon order. Furthermore, in definite conditions, when seeking the Rényi information measures that best exploit stochastic resonance, then nontrivial orders differing from the Shannon case usually emerge. In this way, through binary information transmission, stochastic resonance identifies optimal Rényi measures of information differing from the classic Shannon measure. A confrontation of the quantitative information measures with visual perception is also proposed in an experiment of noise-aided binary image transmission.

  9. Mapping liquid hazardous waste migration in ground water with electromagnetic terrain conductivity measurement

    International Nuclear Information System (INIS)

    Ketelle, R.H.; Pin, F.G.

    1984-01-01

    Electromagnetic conductivity measurements were used to map apparent ground conductivity in the vicinity of a liquid hazardous waste disposal site. Approximately 600 conductivity measurements were obtained to prepare a conductivity map of the site which includes an area of 12 ha (30 acres). Conductivity measurements in the area correlate with specific conductance measurements of surface and ground water samples. Contouring of the conductivity data located contaminant migration pathways in the subsurface. A complex contaminant plume was defined by the conductivity survey. Conductivity values obtained reflected anisotropic characteristics related to local bedrock structure. Anisotropic characteristics of measurements and the use of different instrument configurations indicated semiquantitatively the depth of the high conductivity zone and the direction of flow. 4 references, 2 figures

  10. A laser microsurgical method of cell wall removal allows detection of large-conductance ion channels in the guard cell plasma membrane

    Science.gov (United States)

    Miedema, H.; Henriksen, G. H.; Assmann, S. M.; Evans, M. L. (Principal Investigator)

    1999-01-01

    Application of patch clamp techniques to higher-plant cells has been subject to the limitation that the requisite contact of the patch electrode with the cell membrane necessitates prior enzymatic removal of the plant cell wall. Because the wall is an integral component of plant cells, and because cell-wall-degrading enzymes can disrupt membrane properties, such enzymatic treatments may alter ion channel behavior. We compared ion channel activity in enzymatically isolated protoplasts of Vicia faba guard cells with that found in membranes exposed by a laser microsurgical technique in which only a tiny portion of the cell wall is removed while the rest of the cell remains intact within its tissue environment. "Laser-assisted" patch clamping reveals a new category of high-conductance (130 to 361 pS) ion channels not previously reported in patch clamp studies on plant plasma membranes. These data indicate that ion channels are present in plant membranes that are not detected by conventional patch clamp techniques involving the production of individual plant protoplasts isolated from their tissue environment by enzymatic digestion of the cell wall. Given the large conductances of the channels revealed by laser-assisted patch clamping, we hypothesize that these channels play a significant role in the regulation of ion content and electrical signalling in guard cells.

  11. Local gas- and liquid-phase measurements for air-water two-phase flows in a rectangular channel

    International Nuclear Information System (INIS)

    Zhou, X.; Sun, X.; Williams, M.; Fu, Y.; Liu, Y.

    2014-01-01

    Local gas- and liquid-phase measurements of various gas-liquid two-phase flows, including bubbly, cap-bubbly, slug, and churn-turbulent flows, were performed in an acrylic vertical channel with a rectangular cross section of 30 mm x 10 mm and height of 3.0 m. All the measurements were carried out at three measurement elevations along the flow channel, with z/D h = 9, 72, and 136, respectively, to study the flow development. The gas-phase velocity, void fraction, and bubble number frequency were measured using a double-sensor conductivity probe. A high-speed imaging system was utilized to perform the flow regime visualization and to provide additional quantitative information of the two-phase flow structure. An image processing scheme was developed to obtain the gas-phase velocity, void fraction, Sauter mean diameter, bubble number density, and interfacial area concentration. The liquid-phase velocity and turbulence measurements were conducted using a particle image velocimetry-planar laser-induced fluorescence (PIV-PLIF) system, which enables whole-field and high-resolution data acquisition. An optical phase separation method, which uses fluorescent particles and optical filtration technique, is adopted to extract the velocity information of the liquid phase. An image pre-processing scheme is imposed on the raw PIV images acquired to remove noises due to the presence of bubble residuals and optically distorted particles in the images captured by the PIV-PLIF system. Due to the better light access and less bubble distortion in the narrow rectangular channel, the PIV-PLIF system were able to perform reasonably well in flows of even higher void fractions as compared to the situations with circular pipe test sections. The flow conditions being studied covered various flow regime transitions, void fractions, and liquid-phase flow Reynolds numbers. The obtained experimental data can also be used to validate two-phase CFD results. (author)

  12. Process and device for controlling the operatability of a measuring channel in safety arrangements

    International Nuclear Information System (INIS)

    Edelmann, M.

    1983-01-01

    In addition to the neutron - and temperature - measuring channels, the detectors and thermocouples for active functional testing are also included in the safety circuits. The measuring parameter (neutron flux or coolant outlet temperature) is modulated by the output control system or output and/or coolant flow. This modulation is determined using an auxillary parameter (movement of control rods or neutron flux). To represent the actual value of the measuring parameter to be compared with the previously determined reference value, there is a division of the relative change of the neutron flux or the coolant outlet temperature by the change of control rod position or reactor output caused by it. The effect of the auxiliary parameter on the measured parameter is measured by the cross correlation of both of them and of the auxiliary parameter directly or by auto correlation. The coarse and fine monitoring of the measuring channels takes place with different time constants. (orig./PW)

  13. Novel Quantification of Sediment Concentration in Turbidity Currents Through in-situ Measurements of Conductivity and Temperature

    Science.gov (United States)

    Xu, J.; Wang, Z.; Gwiazda, R.; Paull, C. K.; Talling, P.; Parsons, D. R.; Maier, K. L.; Simmons, S.; Cartigny, M.

    2017-12-01

    During a large turbidity current event observed by seven moorings placed along Monterey Canyon, offshore central California, in the axial channel between 300 and 1900 meters water depth, a conductivity/temperature sensor placed 11 meters above canyon floor on the mooring at 1500 meters water depth recorded a rapid decrease of conductivity and increase of temperature during the passage of a large turbidity current. The conductivity decline is unlikely caused by fresh water input owing to lack of precipitation in the region prior to the event. We investigated the mechanisms of turbidity currents' high sediment concentration reducing the measured conductivity. By conducting a series of laboratory experiments with a range of different concentrations, grain size, and water temperature combinations, we quantified a relationship between reduced conductivity and the elevated sediment concentration. This relationship can be used for estimating the very high sediment concentrations in a turbidity current with a condition of assuming constant salinity of the ambient seawater. The empirical relationship was then applied to the in-situ time-series of temperature and conductivity measured during this turbidity current. The highest sediment concentration, in the head of the flow, reached nearly 400 g/L (volume concentration 17%). Such a high value, which has yet been reported in literature for an oceanic turbidity current, will have significant implications for the dynamics and deposits of such flows.

  14. Design of instantaneous liquid film thickness measurement system for conductive or non-conductive fluid with high viscosity

    Directory of Open Access Journals (Sweden)

    Yongxin Yu

    2017-06-01

    Full Text Available In the paper, a new capacitive sensor with a dielectric film coating was designed to measure the thickness of the liquid film on a flat surface. The measured medium can be conductive or non-conductive fluid with high viscosity such as silicone oil, syrup, CMC solution and melt. With the dielectric film coating, the defects caused by the humidity in a capacitor can be avoided completely. With a excitation frequency 0-20kHz, the static permittivity of capacitive sensor is obtained and stable when small thicknesses are monitored within the frequency of 0-3kHz. Based on the measurement principle, an experimental system was designed and verified including calibration and actual measurement for different liquid film thickness. Experimental results showed that the sensitivity, the resolution, repeatability and linear range of the capacitive sensor are satisfied to the liquid film thickness measurement. Finally, the capacitive measuring system was successfully applied to the water, silicone oil and syrup film thickness measurement.

  15. Use of electromagnetic terrain conductivity measurements to map liquid hazardous waste migration in groundwater

    International Nuclear Information System (INIS)

    Ketelle, R.H.; Pin, F.G.

    1983-11-01

    Electromagnetic conductivity measurements have been used to map apparent ground conductivity in the vicinity of a liquid hazardous waste disposal site. An area of approximately 12 ha (30 acres) was surveyed. Approximately 600 conductivity measurements were obtained to prepare a conductivity map of the site. Conductivity measurments in the area correlate with specific conductance measurements of surface and groundwater samples. Contouring of the conductivity data showed the precise location of contaminant migration pathways in the subsurface. A complex contaminant plume was defined by the conductivity survey. Conductivity values obtained reflected anisotropic characteristics related to local bedrock structure. Anisotropy characteristics and the use of different instrument configurations indicated semiquantitatively the depth of the high conductivity zone and the direction of flow

  16. Kaempferol stimulates large conductance Ca2+-activated K+ (BKCa) channels in human umbilical vein endothelial cells via a cAMP/PKA-dependent pathway

    Science.gov (United States)

    Xu, Y C; Leung, G P H; Wong, P Y D; Vanhoutte, P M; Man, R Y K

    2008-01-01

    Background and purpose: Kaempferol has been shown to possess a vasodilator effect but its mechanism of action remains unclear. In this study, experiments were carried out to study the effect of kaempferol on K+ channels in endothelial cells. Experimental approach: K+ channel activities in human umbilical vein endothelial cells (HUVECs) were studied by conventional whole cell and cell-attached patch-clamp electrophysiology. Key results: Kaempferol stimulated an outward-rectifying current in HUVECs in a dose-dependent manner with an EC50 value of 2.5±0.02 μM. This kaempferol-induced current was abolished by large conductance Ca2+-activated K+ (BKCa) channel blockers, such as iberiotoxin (IbTX) and charybdotoxin (ChTX), whereas the small conductance Ca2+-activated K+ (SKCa) channel blocker, apamin, and the voltage-dependent K+ (KV) channel blocker, 4-aminopyridine, had no effect. Cell-attached patches demonstrated that kaempferol increased the open probability of BkCa channels in HUVECs. Clamping intracellular Ca2+ did not prevent kaempferol-induced increases in outward current. In addition, the kaempferol-induced current was diminished by the adenylyl cyclase inhibitor SQ22536, the cAMP antagonist Rp-8-Br-cAMP and the PKA inhibitor KT5720, but was not affected by the guanylyl cyclase inhibitor ODQ, the cGMP antagonist Rp-8-Br-cGMP and the PKG inhibitor KT5823. The activation of BKCa channels by kaempferol caused membrane hyperpolarization of HUVECs. Conclusion and implications: These results demonstrate that kaempferol activates the opening of BKCa channels in HUVECs via a cAMP/PKA-dependent pathway, resulting in membrane hyperpolarization. This mechanism may partly account for the vasodilator effects of kaempferol. PMID:18493242

  17. (n,p) emission channeling measurements on ion-implanted beryllium

    CERN Multimedia

    Jakubek, J; Uher, J

    2007-01-01

    We propose to perform emission-channeling measurements using thermal neutron induced proton emission from ion-implanted $^{7}$Be. The physics questions addressed concern the beryllium doping of III-V and II-VI semiconductors and the host dependence of the electron capture half-life of $^{7}$Be.

  18. Multiuser MIMO Channel Measurements and Performance in a Large Office Environment

    DEFF Research Database (Denmark)

    Bauch, Gerhard; Andersen, Jørgen Bach; Guthy, Christian

    2007-01-01

    We consider a multiuser MIMO-OFDMA scheme which exploits multiuser diversity in all dimensions: time, frequency and space. The main contribution of this paper is the evaluation and explanation of multiuser MIMO in a real world scenario, i.e. a large office room, based on measured channels. We rep...

  19. Measurement of the Higgs properties in bosonic decay channels at 13 TeV in ATLAS

    CERN Document Server

    Haney, Bijan; The ATLAS collaboration

    2017-01-01

    In 2015 and 2016, ATLAS collected proton-proton collision data at the Large Hadron Collider corresponding to an integrated luminosity of $36.1 \\text{fb}^{−1}$ at a centre-of-mass energy of 13 TeV. The inclusive and differential cross section of the Higgs has been measured in multiple production modes and decay channels in order to learn about the properties of the Higgs. This talk concentrates on the cross sections calculated from the bosonic decay channels $H \\rightarrow ZZ^* \\rightarrow 4\\ell $, $H \\rightarrow WW^* \\rightarrow \\ell\

  20. Testing digital recursive filtering method for radiation measurement channel using pin diode detector

    International Nuclear Information System (INIS)

    Talpalariu, C. M.; Talpalariu, J.; Popescu, O.; Mocanasu, M.; Lita, I.; Visan, D. A.

    2016-01-01

    In this work we have studied a software filtering method implemented in a pulse counting computerized measuring channel using PIN diode radiation detector. In case our interest was focalized for low rate decay radiation measurement accuracies improvement and response time optimization. During works for digital mathematical algorithm development, we used a hardware radiation measurement channel configuration based on PIN diode BPW34 detector, preamplifier, filter and programmable counter, computer connected. We report measurement results using two digital recursive methods in statically and dynamically field evolution. Software for graphical input/output real time diagram representation was designed and implemented, facilitating performances evaluation between the response of fixed configuration software recursive filter and dynamically adaptive configuration recursive filter. (authors)

  1. Neurogenic detrusor overactivity is associated with decreased expression and function of the large conductance voltage- and Ca(2+-activated K(+ channels.

    Directory of Open Access Journals (Sweden)

    Kiril L Hristov

    Full Text Available Patients suffering from a variety of neurological diseases such as spinal cord injury, Parkinson's disease, and multiple sclerosis often develop neurogenic detrusor overactivity (NDO, which currently lacks a universally effective therapy. Here, we tested the hypothesis that NDO is associated with changes in detrusor smooth muscle (DSM large conductance Ca(2+-activated K(+ (BK channel expression and function. DSM tissue samples from 33 patients were obtained during open bladder surgeries. NDO patients were clinically characterized preoperatively with pressure-flow urodynamics demonstrating detrusor overactivity, in the setting of a clinically relevant neurological condition. Control patients did not have overactive bladder and did not have a clinically relevant neurological disease. We conducted quantitative polymerase chain reactions (qPCR, perforated patch-clamp electrophysiology on freshly-isolated DSM cells, and functional studies on DSM contractility. qPCR experiments revealed that DSM samples from NDO patients showed decreased BK channel mRNA expression in comparison to controls. Patch-clamp experiments demonstrated reduced whole cell and transient BK currents (TBKCs in freshly-isolated DSM cells from NDO patients. Functional studies on DSM contractility showed that spontaneous phasic contractions had a decreased sensitivity to iberiotoxin, a selective BK channel inhibitor, in DSM strips isolated from NDO patients. These results reveal the novel finding that NDO is associated with decreased DSM BK channel expression and function leading to increased DSM excitability and contractility. BK channel openers or BK channel gene transfer could be an alternative strategy to control NDO. Future clinical trials are needed to evaluate the value of BK channel opening drugs or gene therapies for NDO treatment and to identify any possible adverse effects.

  2. Identification of Loop D Domain Amino Acids in the Human Aquaporin-1 Channel Involved in Activation of the Ionic Conductance and Inhibition by AqB011

    Directory of Open Access Journals (Sweden)

    Mohamad Kourghi

    2018-04-01

    Full Text Available Aquaporins are integral proteins that facilitate the transmembrane transport of water and small solutes. In addition to enabling water flux, mammalian Aquaporin-1 (AQP1 channels activated by cyclic GMP can carry non-selective monovalent cation currents, selectively blocked by arylsulfonamide compounds AqB007 (IC50 170 μM and AqB011 (IC50 14 μM. In silico models suggested that ligand docking might involve the cytoplasmic loop D (between AQP1 transmembrane domains 4 and 5, but the predicted site of interaction remained to be tested. Work here shows that mutagenesis of two conserved arginine residues in loop D slowed the activation of the AQP1 ion conductance and impaired the sensitivity of the channel to block by AqB011. Substitution of residues in loop D with proline showed effects on ion conductance amplitude that varied with position, suggesting that the structural conformation of loop D is important for AQP1 channel gating. Human AQP1 wild type, AQP1 mutant channels with alanines substituted for two arginines (R159A+R160A, and mutants with proline substituted for single residues threonine (T157P, aspartate (D158P, arginine (R159P, R160P, or glycine (G165P were expressed in Xenopus laevis oocytes. Conductance responses were analyzed by two-electrode voltage clamp. Optical osmotic swelling assays and confocal microscopy were used to confirm mutant and wild type AQP1-expressing oocytes were expressed in the plasma membrane. After application of membrane-permeable cGMP, R159A+R160A channels had a significantly slower rate of activation as compared with wild type, consistent with impaired gating. AQP1 R159A+R160A channels showed no significant block by AqB011 at 50 μM, in contrast to the wild type channel which was blocked effectively. T157P, D158P, and R160P mutations had impaired activation compared to wild type; R159P showed no significant effect; and G165P appeared to augment the conductance amplitude. These findings provide evidence for the

  3. The Large Office Environment - Measurement and Modeling of the Wideband Radio Channel

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Nielsen, Jesper Ødum; Bauch, Gerhard

    2006-01-01

    In a future 4G or WLAN wideband application we can imagine multiple users in a large office environment con-sisting of a single room with partitions. Up to now, indoor radio channel measurement and modelling has mainly concentrated on scenarios with several office rooms and corridors. We present...... here measurements at 5.8GHz for 100 MHz bandwidth and a novel modelling approach for the wideband radio channel in a large office room envi-ronment. An acoustic like reverberation theory is pro-posed that allows to specify a tapped delay line model just from the room dimensions and an average...... calculated from the measurements. The pro-posed model can likely also be applied to indoor hot spot scenarios....

  4. Experimental Characterization of Ultra-Wideband Channel Parameter Measurements in an Underground Mine

    Directory of Open Access Journals (Sweden)

    B. Nkakanou

    2011-01-01

    Full Text Available Experimental results for an ultra-wideband (UWB channel parameters in an underground mining environment over a frequency range of 3 GHz to 10 GHz are reported. The measurements were taken both in LOS and NLOS cases in two different size mine galleries. In the NLOS case, results were acquired for different corridor obstruction angles. The results were obtained during an extensive measurement campaign in the UWB frequency, and the measurement procedure allows both the large- and small-scale parameters such as the path loss exponent, coherence bandwidth, and so forth, to be quantified. The capacity of the UWB channel as a function of the physical depth of the mine gallery has also been recorded for comparison purposes.

  5. Small-conductance calcium-activated potassium (SK) channels contribute to action potential repolarization in human atria

    DEFF Research Database (Denmark)

    Skibsbye, Lasse; Poulet, Claire; Diness, Jonas Goldin

    2014-01-01

    (+) currents by ∼15% and prolonged action potential duration (APD), but no effect was observed in myocytes from AF patients. In trabeculae muscle strips from right atrial appendages of SR patients, both compounds increased APD and effective refractory period, and depolarized the resting membrane potential......, while only NS8593 induced these effects in tissue from AF patients. SK channel inhibition did not alter any electrophysiological parameter in human interventricular septum tissue. CONCLUSIONS: SK channels are present in human atria where they participate in repolarization. SK2 and SK3 were down...

  6. Phase distribution measurements in narrow rectangular channels using image processing techniques

    International Nuclear Information System (INIS)

    Bentley, C.; Ruggles, A.

    1991-01-01

    Many high flux research reactor fuel assemblies are cooled by systems of parallel narrow rectangular channels. The HFIR is cooled by single phase forced convection under normal operating conditions. However, two-phase forced convection or two phase mixed convection can occur in the fueled region as a result of some hypothetical accidents. Such flow conditions would occur only at decay power levels. The system pressure would be around 0.15 MPa in such circumstances. Phase distribution of air-water flow in a narrow rectangular channel is examined using image processing techniques. Ink is added to the water and clear channel walls are used to allow high speed still photographs and video tape to be taken of the air-water flow field. Flow field images are digitized and stored in a Macintosh 2ci computer using a frame grabber board. Local grey levels are related to liquid thickness in the flow channel using a calibration fixture. Image processing shareware is used to calculate the spatially averaged liquid thickness from the image of the flow field. Time averaged spatial liquid distributions are calculated using image calculation algorithms. The spatially averaged liquid distribution is calculated from the time averaged spatial liquid distribution to formulate the combined temporally and spatially averaged fraction values. The temporally and spatially averaged liquid fractions measured using this technique compare well to those predicted from pressure gradient measurements at zero superficial liquid velocity

  7. Galvanically Decoupled Current Source Modules for Multi-Channel Bioimpedance Measurement Systems

    Directory of Open Access Journals (Sweden)

    Roman Kusche

    2017-10-01

    Full Text Available Bioimpedance measurements have become a useful technique in the past several years in biomedical engineering. Especially, multi-channel measurements facilitate new imaging and patient monitoring techniques. While most instrumentation research has focused on signal acquisition and signal processing, this work proposes the design of an excitation current source module that can be easily implemented in existing or upcoming bioimpedance measurement systems. It is galvanically isolated to enable simultaneous multi-channel bioimpedance measurements with a very low channel-coupling. The system is based on a microcontroller in combination with a voltage-controlled current source circuit. It generates selectable sinusoidal excitation signals between 0.12 and 1.5 mA in a frequency range from 12 to 250 kHz, whereas the voltage compliance range is ±3.2 V. The coupling factor between two current sources, experimentally galvanically connected with each other, is measured to be less than −48 dB over the entire intended frequency range. Finally, suggestions for developments in the future are made.

  8. Importance of large conductance calcium-activated potassium channels (BKCa) in interleukin-1b-induced adhesion of monocytes to endothelial cells.

    Science.gov (United States)

    Burgazli, K M; Venker, C J; Mericliler, M; Atmaca, N; Parahuleva, M; Erdogan, A

    2014-01-01

    The present study investigated the role of the large conductance calcium-activated potassium channels (BKCa) in interleukin-1b (IL-1b) induced inflammation. Human umbilical vein endothelial cells (HUVECs) were isolated and cultured. Endothelial cell membrane potential measurements were accomplished using the fluorescent dye DiBAC4(3). The role of BKCa was assessed using iberiotoxin, a highly selective BKCa inhibitor. Changes in the calcium intracellular calcium were investigated using Fura-2-AM imaging. Fluorescent dyes DCF-AM and DAF-AM were further used in order to measure the formation of reactive oxygen species (ROS) and nitric oxide (NO) synthesis, respectively. Endothelial cell adhesion tests were conducted with BCECF-AM adhesion assay and tritium thymidine uptake using human monocytic cells (U937). Expression of cellular adhesion molecules (ICAM-1, VCAM-1) was determined by flow cytometer. Interleukin-1b induced a BKCa dependent hyperpolarization of HUVECs. This was followed by an increase in the intracellular calcium concentration. Furthermore, IL-1b significantly increased the synthesis of NO and ROS. The increase of intracellular calcium, radicals and NO resulted in a BKCa dependent adhesion of monocytes to HUVECs. Endothelial cells treated with IL-1b expressed both ICAM-1 and VCAM-1 in significantly higher amounts as when compared to controls. It was further shown that the cellular adhesion molecules ICAM-1 and VCAM-1 were responsible for the BKCa-dependent increase in cellular adhesion. Additionally, inhibition of the NADPH oxidase with DPI led to a significant downregulation of IL-1b-induced expression of ICAM and VCAM, as well as inhibition of eNOS by L-NMMA, and intracellular calcium by BAPTA. Activation of the endothelial BKCa plays an important role in the IL-1b-induced monocyte adhesion to endothelial cells.

  9. Analysis of systematic error deviation of water temperature measurement at the fuel channel outlet of the reactor Maria

    International Nuclear Information System (INIS)

    Bykowski, W.

    2000-01-01

    The reactor Maria has two primary cooling circuits; fuel channels cooling circuit and reactor pool cooling circuit. Fuel elements are placed inside the fuel channels which are parallely linked in parallel, between the collectors. In the course of reactor operation the following measurements are performed: continuous measurement of water temperature at the fuel channels inlet, continuous measurement of water temperature at the outlet of each fuel channel and continuous measurement of water flow rate through each fuel channel. Based on those thermal-hydraulic parameters the instantaneous thermal power generated in each fuel channel is determined and by use of that value the thermal balance and the degree of fuel burnup is assessed. The work contains an analysis concerning estimate of the systematic error of temperature measurement at outlet of each fuel channel and so the erroneous assessment of thermal power extracted in each fuel channel and the burnup degree for the individual fuel element. The results of measurements of separate factors of deviations for the fuel channels are enclosed. (author)

  10. Sensitivity analysis of a new SWIR-channel measuring tropospheric CH 4 and CO from space

    Science.gov (United States)

    Jongma, Rienk T.; Gloudemans, Annemieke M. S.; Hoogeveen, Ruud W. M.; Aben, Ilse; de Vries, Johan; Escudero-Sanz, Isabel; van den Oord, Gijsbertus; Levelt, Pieternel F.

    2006-08-01

    In preparation for future atmospheric space missions a consortium of Dutch organizations is performing design studies on a nadir viewing grating-based imaging spectrometer using OMI and SCIAMACHY heritage. The spectrometer measures selected species (O 3, NO II, HCHO, H IIO, SO II, aerosols (optical depth, type and absorption index), CO and CH4) with sensitivity down to the Earth's surface, thus addressing science issues on air quality and climate. It includes 3 UV-VIS channels continuously covering the 270-490 nm range, a NIR-channel covering the 710-775 nm range, and a SWIR-channel covering the 2305-2385 nm range. This instrument concept is, named TROPOMI, part of the TRAQ-mission proposal to ESA in response to the Call for Earth Explorer Ideas 2005, and, named TROPI, part of the CAMEO-proposal prepared for the US NRC decadal study-call on Earth science and applications from space. The SWIR-channel is optional in the TROPOMI/TRAQ instrument and included as baseline in the TROPI/CAMEO instrument. This paper focuses on derivation of the instrument requirements of the SWIR-channel by presenting the results of retrieval studies. Synthetic detector spectra are generated by the combination of a forward model and an instrument simulator that includes the properties of state-of-the-art detector technology. The synthetic spectra are input to the CO and CH 4 IMLM retrieval algorithm originally developed for SCIAMACHY. The required accuracy of the Level-2 SWIR data products defines the main instrument parameters like spectral resolution and sampling, telescope aperture, detector temperature, and optical bench temperature. The impact of selected calibration and retrieval errors on the Level-2 products has been characterized. The current status of the SWIR-channel optical design with its demanding requirements on ground-pixel size, spectral resolution, and signal-to-noise ratio will be presented.

  11. Fluid Distribution in Synthetic Wet Halite Rocks : Inference from Measured Elastic Wave Velocity and Electrical Conductivity

    Science.gov (United States)

    Watanabe, T.; Kitano, M.

    2011-12-01

    isolated worm-like channels. In this presentation, we will report preliminary results of compressional wave velocity and electrical conductivity measurements.

  12. Magneto-acousto-electrical Measurement Based Electrical Conductivity Reconstruction for Tissues.

    Science.gov (United States)

    Zhou, Yan; Ma, Qingyu; Guo, Gepu; Tu, Juan; Zhang, Dong

    2018-05-01

    Based on the interaction of ultrasonic excitation and magnetoelectrical induction, magneto-acousto-electrical (MAE) technology was demonstrated to have the capability of differentiating conductivity variations along the acoustic transmission. By applying the characteristics of the MAE voltage, a simplified algorithm of MAE measurement based conductivity reconstruction was developed. With the analyses of acoustic vibration, ultrasound propagation, Hall effect, and magnetoelectrical induction, theoretical and experimental studies of MAE measurement and conductivity reconstruction were performed. The formula of MAE voltage was derived and simplified for the transducer with strong directivity. MAE voltage was simulated for a three-layer gel phantom and the conductivity distribution was reconstructed using the modified Wiener inverse filter and Hilbert transform, which was also verified by experimental measurements. The experimental results are basically consistent with the simulations, and demonstrate that the wave packets of MAE voltage are generated at tissue interfaces with the amplitudes and vibration polarities representing the values and directions of conductivity variations. With the proposed algorithm, the amplitude and polarity of conductivity gradient can be restored and the conductivity distribution can also be reconstructed accurately. The favorable results demonstrate the feasibility of accurate conductivity reconstruction with improved spatial resolution using MAE measurement for tissues with conductivity variations, especially suitable for nondispersive tissues with abrupt conductivity changes. This study demonstrates that the MAE measurement based conductivity reconstruction algorithm can be applied as a new strategy for nondestructive real-time monitoring of conductivity variations in biomedical engineering.

  13. Numerical Investigation of the Thermal Regime of Underground Channel Heat Pipelines Under Flooding Conditions with the Use of a Conductive-Convective Heat Transfer Model

    Science.gov (United States)

    Polovnikov, V. Yu.

    2018-05-01

    This paper presents the results of numerical analysis of thermal regimes and heat losses of underground channel heating systems under flooding conditions with the use of a convective-conductive heat transfer model with the example of the configuration of the heat pipeline widely used in the Russian Federation — a nonpassage ferroconcrete channel (crawlway) and pipelines insulated with mineral wool and a protective covering layer. It has been shown that convective motion of water in the channel cavity of the heat pipeline under flooding conditions has no marked effect on the intensification of heat losses. It has been established that for the case under consideration, heat losses of the heat pipeline under flooding conditions increase from 0.75 to 52.39% due to the sharp increase in the effective thermal characteristics of the covering layer and the heat insulator caused by their moistening.

  14. Noninvasive electrical conductivity measurement by MRI. A test of its validity and the electrical conductivity characteristics of glioma

    Energy Technology Data Exchange (ETDEWEB)

    Tha, Khin Khin; Kudo, Kohsuke [Hokkaido University Hospital, Department of Diagnostic and Interventional Radiology, N-14, W-5, Kita-ku, Sapporo (Japan); Hokkaido University, Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education, Sapporo (Japan); Katscher, Ulrich; Stehning, Christian [Philips Research Laboratories, Hamburg (Germany); Yamaguchi, Shigeru; Terasaka, Shunsuke; Kazumata, Ken [Faculty of Medicine, Hokkaido University, Department of Neurosurgery, Sapporo (Japan); Fujima, Noriyuki [Hokkaido University Hospital, Department of Diagnostic and Interventional Radiology, N-14, W-5, Kita-ku, Sapporo (Japan); Yamamoto, Toru [Hokkaido University, Faculty of Health Sciences, Sapporo (Japan); Van Cauteren, Marc [Clinical Science Philips Healthtech Asia Pacific, Tokyo (Japan); Shirato, Hiroki [Hokkaido University, Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education, Sapporo (Japan); Faculty of Medicine, Hokkaido University, Department of Radiation Medicine, Sapporo (Japan)

    2018-01-15

    This study noninvasively examined the electrical conductivity (σ) characteristics of diffuse gliomas using MRI and tested its validity. MRI including a 3D steady-state free precession (3D SSFP) sequence was performed on 30 glioma patients. The σ maps were reconstructed from the phase images of the 3D SSFP sequence. The σ histogram metrics were extracted and compared among the contrast-enhanced (CET) and noncontrast-enhanced tumour components (NCET) and normal brain parenchyma (NP). Difference in tumour σ histogram metrics among tumour grades and correlation of σ metrics with tumour grades were tested. Validity of σ measurement using this technique was tested by correlating the mean tumour σ values measured using MRI with those measured ex vivo using a dielectric probe. Several σ histogram metrics of CET and NCET of diffuse gliomas were significantly higher than NP (Bonferroni-corrected p ≤.045). The maximum σ of NCET showed a moderate positive correlation with tumour grade (r =.571, Bonferroni-corrected p =.018). The mean tumour σ measured using MRI showed a moderate positive correlation with the σ measured ex vivo (r =.518, p =.040). Tissue σ can be evaluated using MRI, incorporation of which may better characterise diffuse gliomas. (orig.)

  15. Role of calcium-activated potassium channels with small conductance in bradykinin-induced vasodilation of porcine retinal arterioles

    DEFF Research Database (Denmark)

    Dalsgaard, Thomas; Kroigaard, Christel; Bek, Toke

    2009-01-01

    PURPOSE: Endothelial dysfunction and impaired vasodilation may be involved in the pathogenesis of retinal vascular diseases. In the present study, the mechanisms underlying bradykinin vasodilation were examined and whether calcium-activated potassium channels of small (SK(Ca)) and intermediate (IK...

  16. A wireless multi-channel bioimpedance measurement system for personalized healthcare and lifestyle.

    Science.gov (United States)

    Ramos, Javier; Ausín, José Luis; Lorido, Antonio Manuel; Redondo, Francisco; Duque-Carrillo, Juan Francisco

    2013-01-01

    Miniaturized, noninvasive, wearable sensors constitute a fundamental prerequisite for pervasive, predictive, and preventive healthcare systems. In this sense, this paper presents the design, realization, and evaluation of a wireless multi-channel measurement system based on a cost-effective high-performance integrated circuit for electrical bioimpedance (EBI) measurements in the frequency range from 1 kHz to 1 MHz. The resulting on-chip spectrometer provides high measuring EBI capabilities and together with a low-cost, commercially available radio frequency transceiver device. It provides reliable wireless communication, constitutes the basic node to build EBI wireless sensor networks (EBI-WSNs). The proposed EBI-WSN behaves as a high-performance wireless multi-channel EBI spectrometer, where the number of channels is completely scalable and independently configurable to satisfy specific measurement requirements of each individual. A prototype of the EBI node leads to a very small printed circuit board of approximately 8 cm2 including chip-antenna, which can operate several years on one 3-V coin cell battery and make it suitable for long-term preventive healthcare monitoring.

  17. Conductive Polymer Microelectrodes for on-chip measurement of transmitter release from living cells

    DEFF Research Database (Denmark)

    Larsen, Simon Tylsgaard; Matteucci, Marco; Taboryski, Rafael J.

    2012-01-01

    driven cell trapping inside closed chip devices. Conductive polymer microelectrodes were used to measure transmitter release using electrochemical methods such as cyclic voltammetry and constant potential amperometry. By measuring the oxidation current at a cyclic voltammogram, the concentration...

  18. Conformational Smear Characterization and Binning of Single-Molecule Conductance Measurements for Enhanced Molecular Recognition.

    Science.gov (United States)

    Korshoj, Lee E; Afsari, Sepideh; Chatterjee, Anushree; Nagpal, Prashant

    2017-11-01

    Electronic conduction or charge transport through single molecules depends primarily on molecular structure and anchoring groups and forms the basis for a wide range of studies from molecular electronics to DNA sequencing. Several high-throughput nanoelectronic methods such as mechanical break junctions, nanopores, conductive atomic force microscopy, scanning tunneling break junctions, and static nanoscale electrodes are often used for measuring single-molecule conductance. In these measurements, "smearing" due to conformational changes and other entropic factors leads to large variances in the observed molecular conductance, especially in individual measurements. Here, we show a method for characterizing smear in single-molecule conductance measurements and demonstrate how binning measurements according to smear can significantly enhance the use of individual conductance measurements for molecular recognition. Using quantum point contact measurements on single nucleotides within DNA macromolecules, we demonstrate that the distance over which molecular junctions are maintained is a measure of smear, and the resulting variance in unbiased single measurements depends on this smear parameter. Our ability to identify individual DNA nucleotides at 20× coverage increases from 81.3% accuracy without smear analysis to 93.9% with smear characterization and binning (SCRIB). Furthermore, merely 7 conductance measurements (7× coverage) are needed to achieve 97.8% accuracy for DNA nucleotide recognition when only low molecular smear measurements are used, which represents a significant improvement over contemporary sequencing methods. These results have important implications in a broad range of molecular electronics applications from designing robust molecular switches to nanoelectronic DNA sequencing.

  19. Improving the fidelity of teleportation through noisy channels using weak measurement

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, T., E-mail: tanu.pram99@bose.res.in; Majumdar, A.S., E-mail: archan@bose.res.in

    2013-12-13

    We employ the technique of weak measurement in order to enable preservation of teleportation fidelity for two-qubit noisy channels. We consider one or both qubits of a maximally entangled state to undergo amplitude damping, and show that the application of weak measurement and a subsequent reverse operation could lead to a fidelity greater than 2/3 for any value of the decoherence parameter. The success probability of the protocol decreases with the strength of weak measurement, and is lower when both the qubits are affected by decoherence. Finally, our protocol is shown to work for the Werner state too.

  20. Peculiarities of void fraction measurement applied to physical installation channels cooled by forced helium flow

    International Nuclear Information System (INIS)

    Danilov, V.V.; Filippov, Yu.P.; Mamedov, I.S.

    1989-01-01

    The methods of optimizing the transducers designed for measurements of the void fraction of two-phase flows in the channels of round and annular cross section are presented. On the basis of the analysis performed concrete solution of relatively high technical characteristics are proposed. Rated and actual characteristics of signal ranges and measurement errors are given for both sensors. Influence of the mass velocity on the void fraction of adiabatic two-phase flows is theoretically analyzed. Effects of friction and of liquid-into-vapour entrainment are shown. Calculation results are compared with the obtained experimental data for helium. Special attention is given to the specific features of the processes in channels with different cross section. 17 refs.; 5 figs.; 1 tab

  1. VAMCIS, a new measuring channel for continuous monitoring of leak rates inside PWR steam generators

    International Nuclear Information System (INIS)

    Champion, G.; Dubail, A.; Lefevre, F.

    1988-01-01

    In order to assess the primary to secondary leakage, radioactive isotopes, formed in the primary coolant as a result of fission or neutron capture, are usually monitored in the pressurized water reactor (PWR) secondary coolant. Conventional methods mainly based on the detection of 133 Xe, tritium, and 41 Ar are widely used on French Electricite de France (EdF) PWRs. Some years ago, it appeared necessary to improve both leak rate assessments and steam generator tube rupture (SGTR) detection. A volumetric activity measuring channel inside steam (VAMCIS) has been developed for this purpose. The SGTR that occurred at the North Anna PWR has focused the attention of safety authorities on this new measuring channel. It is planned to implement VAMCIS at North Anna in order to check the leak rate variations more accurately

  2. Flow visualization and velocity measurement in a small-scale open channel using an electron microscope

    International Nuclear Information System (INIS)

    Yasuda, K; Sogo, M; Iwamoto, Y

    2013-01-01

    The present note describes a method for use in conjunction with a scanning electron microscope (SEM) that has been developed to visualize a liquid flow under a high-level vacuum and to measure a velocity field in a small-scale flow through an open channel. In general, liquid cannot be observed via a SEM, because liquid evaporates under the high-vacuum environment of the SEM. As such, ionic liquid and room temperature molten salt having a vapor pressure of nearly zero is used in the present study. We use ionic liquid containing Au-coated tracer particles to visualize a small-scale flow under a SEM. Furthermore, the velocity distribution in the open channel is obtained by particle tracking velocimetry measurement and a parabolic profile is confirmed. (technical design note)

  3. Single-top s channel cross-section measurement with the ATLAS detector

    CERN Document Server

    Monini, Caterina; Lucotte, Arnaud

    The work reported in this thesis is aimed at measuring with the ATLAS detector the only mechanism of top quark electroweak production which has not yet been observed at the Large Hadron Collider: the s-channel. Its interest relies in the confirmation of the Standard Model predictions but, as well, in the possibility of constraining several new physics scenarios when comparing the s-channel cross section with the one of the other single top production modes (the Wt and t-channel). After a general introduction upon top physics and the experimental setup employed for the detection and the reconstruction of the physics objects, we present two analyses realized with proton-proton collisions collected by the ATLAS detector at a center of mass energy of 7 and 8 TeV. Since the s-channel production is characterized by a very low purity and, at the same time, is not favoured at the LHC because it proceeds via quark-antiquark annihilation, a multivariate approach is applied in both cases to discriminate the signal. For ...

  4. Application of Hot-wire Method for Measuring Thermal Conductivity of Fine Ceramics

    Directory of Open Access Journals (Sweden)

    Shangxi WANG

    2016-11-01

    Full Text Available Ceramic substrate is preferred in high density packaging due to its high electrical resistivity and moderate expansion coefficient. The thermal conductivity is a key parameter for packaging substrates. There are two common methods to measure the thermal conductivity, which are the hot-wire method and the laser-flash method. Usually, the thermal conductivities of porcelain is low and meet the measurement range of hot-wire method, and the measured value by hot-wire method has little difference with that by laser-flash method. In recent years, with the requirement of high-powered LED lighting, some kinds of ceramic substrates with good thermal conductivity have been developed and their thermal conductivity always measured by the means of laser flash method, which needs expensive instrument. In this paper, in order to detect the thermal conductivity of fine ceramic with convenience and low cost, the feasibility of replacing the laser flash method with hot wire method to measure thermal conductivity of ceramic composites was studied. The experiment results showed that the thermal conductivity value of fine ceramics measured by the hot-wire method is severely lower than that by the laser-flash method. However, there is a positive relationship between them. It is possible to measure the thermal conductivity of fine ceramic workpiece instantly by hot-wire method via a correction formula.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12543

  5. Comparative measurements of proton dechanneling in silicon under channeling, blocking and double alignment conditions

    International Nuclear Information System (INIS)

    Kerkow, H.; Pietsch, H.; Taeubner, F.

    1980-01-01

    Backscattering yields of 300 keV protons are measured under channeling (sub(ch)), blocking (sub(bl)) and double alignment (sub(da)) conditions on (111)-silicon crystals. It was established that the relation sub(ch)-sub(bl)sub(da) is fulfilled within an experimental error of 10% for clean surfaces as well as for vacuum deposited layers on the crystal surface. (author)

  6. Development of conductivity probe and temperature probe for in-situ measurements in hydrological studies

    International Nuclear Information System (INIS)

    Chandra, U.; Galindo, B.J.; Castagnet, A.C.G.

    1981-05-01

    A conductivity probe and a temperature probe have been developed for in-situ measurements in various hydrological field studies. The conductivity probe has platinum electrodes and is powered with two 12 volt batteries. The sensing element of the temperature probe consists of a resistor of high coefficient of temperature. Response of the conductivity probe is measured in a milliampere mater while the resistance of the thermistor is read by a digital meter. The values of conductivity and temperature are derived from respective calibration. The probes are prototype and their range of measurement can be improved depending upon the requirement of the field problem. (Author) [pt

  7. In-pile measurement of the thermal conductivity of irradiated metallic fuel

    International Nuclear Information System (INIS)

    Bauer, T.H.; Holland, J.W.

    1995-01-01

    Transient test data and posttest measurements from recent in-pile overpower transient experiments are used for an in situ determination of metallic fuel thermal conductivity. For test pins that undergo melting but remain intact, a technique is described that relates fuel thermal conductivity to peak pin power during the transient and a posttest measured melt radius. Conductivity estimates and their uncertainty are made for a database of four irradiated Integral Fast Reactor-type metal fuel pins of relatively low burnup (<3 at.%). In the assessment of results, averages and trends of measured fuel thermal conductivity are correlated to local burnup. Emphasis is placed on the changes of conductivity that take place with burnup-induced swelling and sodium logging. Measurements are used to validate simple empirically based analytical models that describe thermal conductivity of porous media and that are recommended for general thermal analyses of irradiated metallic fuel

  8. Safety assessment of inter-channel / inter-system digital communications: A defensive measures approach

    International Nuclear Information System (INIS)

    Thuy, N. N. Q.

    2006-01-01

    Inappropriately designed inter-channel and inter-system digital communications could initiate common cause failure of multiple channels or multiple systems. Defensive measures were introduced in EPRI report TR-1002835 (Guideline for Performing Defense-in-Depth and Diversity Assessments for Digital Upgrades) to assess, on a deterministic basis, the susceptibility of digital systems architectures to common-cause failures. This paper suggests how this approach could be applied to assess inter-channel and inter-system digital communications from a safety standpoint. The first step of the approach is to systematically identify the so called 'influence factors' that one end of the data communication path can have on the other. Potential factors to be considered would typically include data values, data volumes and data rates. The second step of the approach is to characterize the ways possible failures of a given end of the communication path could affect these influence factors (e.g., incorrect data values, excessive data rates, time-outs, incorrect data volumes). The third step is to analyze the designed-in measures taken to guarantee independence of the other end. In addition to classical error detection and correction codes, typical defensive measures are one-way data communication, fixed-rate data communication, fixed-volume data communication, validation of data values. (authors)

  9. Design and Construction of a Thermal Contact Resistance and Thermal Conductivity Measurement System

    Science.gov (United States)

    2015-09-01

    thank my Mom, Dad , Allison, Jessica, and father-in-law, Tom, for always being there to listen and encourage me. xxiv THIS PAGE INTENTIONALLY...thermal conductivity is temperature measurement inaccuracies. A probe constructed of a poor thermally conductive material when inserted into a hot...interface- resistance-measurement-using-a-transient-method/ [26] H. Fukushima, L. T. Drzal, B. P. Rook and M. J. Rich , “Thermal conductivity of exfoliated

  10. A New Negative Allosteric Modulator AP14145 for the Study of Small Conductance Calcium-Activated Potassium Channels

    DEFF Research Database (Denmark)

    Simo Vicens, Rafel; Kirchhoff, Jeppe Egedal; Dolce, Bernardo

    2017-01-01

    ) prolongation in anaesthetised rats and a beam walk test was performed in mice to determine acute CNS related effects of the drug. Key results: AP14145 was found to be an equipotent negative allosteric modulator of KCa2.2 and KCa2.3 channels (IC50 = 1.1 ± 0.3 μM L-1). The presence of AP14145 (10 μM L-1...

  11. The small molecule NS11021 is a potent and specific activator of Ca2+-activated big-conductance K+ channels

    DEFF Research Database (Denmark)

    Bentzen, Bo Hjorth; Nardi, Antonio; Calloe, Kirstine

    2007-01-01

    , a mitochondrial K(+) channel with KCa1.1-resembling properties has been found in the heart, where it may be involved in regulation of energy consumption. In the present study, the effect of a novel NeuroSearch compound, 1-(3,5-bis-trifluoromethyl-phenyl)-3-[4-bromo-2-(1H-tetrazol-5-yl)-phenyl]-thiourea (NS11021...

  12. Computing rates of Markov models of voltage-gated ion channels by inverting partial differential equations governing the probability density functions of the conducting and non-conducting states.

    Science.gov (United States)

    Tveito, Aslak; Lines, Glenn T; Edwards, Andrew G; McCulloch, Andrew

    2016-07-01

    Markov models are ubiquitously used to represent the function of single ion channels. However, solving the inverse problem to construct a Markov model of single channel dynamics from bilayer or patch-clamp recordings remains challenging, particularly for channels involving complex gating processes. Methods for solving the inverse problem are generally based on data from voltage clamp measurements. Here, we describe an alternative approach to this problem based on measurements of voltage traces. The voltage traces define probability density functions of the functional states of an ion channel. These probability density functions can also be computed by solving a deterministic system of partial differential equations. The inversion is based on tuning the rates of the Markov models used in the deterministic system of partial differential equations such that the solution mimics the properties of the probability density function gathered from (pseudo) experimental data as well as possible. The optimization is done by defining a cost function to measure the difference between the deterministic solution and the solution based on experimental data. By evoking the properties of this function, it is possible to infer whether the rates of the Markov model are identifiable by our method. We present applications to Markov model well-known from the literature. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  13. Offset correction system for 128-channel self-triggering readout chip with in-channel 5-bit energy measurement functionality

    Energy Technology Data Exchange (ETDEWEB)

    Otfinowski, P., E-mail: potfin@agh.edu.pl; Grybos, P.; Szczygiel, R.; Kasinski, K.

    2015-04-21

    We report on a novel, two-stage 8-bit trimming solution dedicated for multichannel systems with reduced trim DAC area occupancy. The presented design was used for comparator offset correction in a 128-channel particle tracking, self-triggering readout system and manufactured in 180 nm CMOS process. The 8-bit trim DAC has a range of ±165 mV, current consumption of 3.2 µA and occupies an area of 37 µm×17 µm in each channel, which corresponds to a 6-bit conventional current steering DAC with similar linearity.

  14. Are U-channels measurements appropriate for reversal or excursion records ?

    Science.gov (United States)

    Philippe, E. G. H.; Valet, J. P.

    2017-12-01

    Sampling of sediment cores by U-channel plastic tubes is a very successful technique that allows to perform measurements of the magnetic remanence and demagnetization of long sections of sediment. This approach made possible the acquisition of detailed records of paleosecular variation, geomagnetic polarity and relative paleointensity over the past million years and yielded significant advances in our knowledge of the geomagnetic field changes. The major pitfall is that the resolution of the signal which is imposed by the deposition rate of the sediment is also attenuated by the response curve of the magnetic sensors used for measurements. This is not so critical to document the dipole field changes, but may have a significant impact to recover fast field changes typical of the non-dipole field that prevail during reversals and excursions. We have investigated possible consequences by comparing 150 successive individual directions of 1 cm side successive single samples with the measurement of the 1.5m equivalent U-channel obtained by placing the same samples adjacent to each other. We compared different transition lengths and generated transitional directions that produce records with similar characteristics as those derived from volcanic records of reversals with a magnetization intensity dropping to 5% of the full polarity value during the transition. The results show that even with transitional intervals as long as 30 cm and therefore associated with deposition rates as high as 10 cm/ka the U-channels considerably smooth all variations with significant consequences on the VGP paths that become more constrained in longitude. Despite little similarity with the global structure of the transition, the U-channels fail to reproduce the complexity of the transitional period. The transitional VGPs never duplicate the variations of the non-dipole field even within several centimeters and generate artificial clusters or periods of apparent fast changes. We are currently

  15. Assessing the performance of multi-purpose channel management measures at increasing scales

    Science.gov (United States)

    Wilkinson, Mark; Addy, Steve

    2016-04-01

    In addition to hydroclimatic drivers, sediment deposition from high energy river systems can reduce channel conveyance capacity and lead to significant increases in flood risk. There is an increasing recognition that we need to work with the interplay of natural hydrological and morphological processes in order to attenuate flood flows and manage sediment (both coarse and fine). This typically includes both catchment (e.g. woodland planting, wetlands) and river (e.g. wood placement, floodplain reconnection) restoration approaches. The aim of this work was to assess at which scales channel management measures (notably wood placement and flood embankment removal) are most appropriate for flood and sediment management in high energy upland river systems. We present research findings from two densely instrumented research sites in Scotland which regularly experience flood events and have associated coarse sediment problems. We assessed the performance of a range of novel trial measures for three different scales: wooded flow restrictors and gully tree planting at the small scale (transport to optimise performance. At the large scale, well designed flood embankment lowering can improve connectivity to the floodplain during low to medium return period events. However, ancillary works to stabilise the bank failed thus emphasising the importance of letting natural processes readjust channel morphology and hydrological connections to the floodplain. Although these trial measures demonstrated limited effects, this may be in part owing to restrictions in the range of hydroclimatological conditions during the study period and further work is needed to assess the performance under more extreme conditions. This work will contribute to refining guidance for managing channel coarse sediment problems in the future which in turn could help mitigate flooding using natural approaches.

  16. Further elucidation of nanofluid thermal conductivity measurement using a transient hot-wire method apparatus

    Science.gov (United States)

    Yoo, Donghoon; Lee, Joohyun; Lee, Byeongchan; Kwon, Suyong; Koo, Junemo

    2018-02-01

    The Transient Hot-Wire Method (THWM) was developed to measure the absolute thermal conductivity of gases, liquids, melts, and solids with low uncertainty. The majority of nanofluid researchers used THWM to measure the thermal conductivity of test fluids. Several reasons have been suggested for the discrepancies in these types of measurements, including nanofluid generation, nanofluid stability, and measurement challenges. The details of the transient hot-wire method such as the test cell size, the temperature coefficient of resistance (TCR) and the sampling number are further investigated to improve the accuracy and consistency of the measurements of different researchers. It was observed that smaller test apparatuses were better because they can delay the onset of natural convection. TCR values of a coated platinum wire were measured and statistically analyzed to reduce the uncertainty in thermal conductivity measurements. For validation, ethylene glycol (EG) and water thermal conductivity were measured and analyzed in the temperature range between 280 and 310 K. Furthermore, a detailed statistical analysis was conducted for such measurements, and the results confirmed the minimum number of samples required to achieve the desired resolution and precision of the measurements. It is further proposed that researchers fully report the information related to their measurements to validate the measurements and to avoid future inconsistent nanofluid data.

  17. Research of Electrical Conductivity Measurement System for Mine Bursting Water Based on Dual Frequency Method

    Directory of Open Access Journals (Sweden)

    Zhou Mengran

    2016-01-01

    Full Text Available This paper presents a double frequency conductivity measurement method for measuring mine bursting water, to solve the capacitance effect of the conductivity sensor itself has the help. The core controller of the system is the single chip microcomputer ATMEGA128. This paper introduces the basic principle of the measurement of the existing problems and the dual frequency measurement method, and then introduces and analyzes the hardware. To test and analyze the collected data, the double frequency method is found to have good stability and accuracy in the measurement of the electrical conductivity of mine inrush water. It is proved that the method and the system design of the hardware circuit can accurately measure the electric conductivity of the mine inrush water source.

  18. Kaempferol enhances endothelium-dependent relaxation in the porcine coronary artery through activation of large-conductance a2+-activated K+ channels

    Science.gov (United States)

    Xu, Y C; Leung, S W S; Leung, G P H; Man, R Y K

    2015-01-01

    Background and Purpose Kaempferol, a plant flavonoid present in normal human diet, can modulate vasomotor tone. The present study aimed to elucidate the signalling pathway through which this flavonoid enhanced relaxation of vascular smooth muscle. Experimental Approach The effect of kaempferol on the relaxation of porcine coronary arteries to endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) relaxing agents was studied in an in vitro organ chamber setup. The whole-cell patch-clamp technique was used to determine the effect of kaempferol on potassium channels in porcine coronary artery smooth muscle cells (PCASMCs). Key Results At a concentration without direct effect on vascular tone, kaempferol (3 × 10−6 M) enhanced relaxations produced by bradykinin and sodium nitroprusside. The potentiation by kaempferol of the bradykinin-induced relaxation was not affected by Nω-nitro-L-arginine methyl ester, an inhibitor of NO synthase (10−4 M) or TRAM-34 plus UCL 1684, inhibitors of intermediate- and small-conductance calcium-activated potassium channels, respectively (10−6 M each), but was abolished by tetraethylammonium chloride, a non-selective inhibitor of calcium-activated potassium channels (10−3 M), and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channel (KCa1.1; 10−7 M). Iberiotoxin also inhibited the potentiation by kaempferol of sodium nitroprusside-induced relaxations. Kaempferol stimulated an outward-rectifying current in PCASMCs, which was abolished by iberiotoxin. Conclusions and Implications The present results suggest that, in smooth muscle cells of the porcine coronary artery, kaempferol enhanced relaxations caused by endothelium-derived and exogenous NO as well as those due to endothelium-dependent hyperpolarization. This vascular effect of kaempferol involved the activation of KCa1.1 channels. PMID:25652142

  19. Kaempferol enhances endothelium-dependent relaxation in the porcine coronary artery through activation of large-conductance Ca(2+) -activated K(+) channels.

    Science.gov (United States)

    Xu, Y C; Leung, S W S; Leung, G P H; Man, R Y K

    2015-06-01

    Kaempferol, a plant flavonoid present in normal human diet, can modulate vasomotor tone. The present study aimed to elucidate the signalling pathway through which this flavonoid enhanced relaxation of vascular smooth muscle. The effect of kaempferol on the relaxation of porcine coronary arteries to endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) relaxing agents was studied in an in vitro organ chamber setup. The whole-cell patch-clamp technique was used to determine the effect of kaempferol on potassium channels in porcine coronary artery smooth muscle cells (PCASMCs). At a concentration without direct effect on vascular tone, kaempferol (3 × 10(-6) M) enhanced relaxations produced by bradykinin and sodium nitroprusside. The potentiation by kaempferol of the bradykinin-induced relaxation was not affected by N(ω)-nitro-L-arginine methyl ester, an inhibitor of NO synthase (10(-4) M) or TRAM-34 plus UCL 1684, inhibitors of intermediate- and small-conductance calcium-activated potassium channels, respectively (10(-6) M each), but was abolished by tetraethylammonium chloride, a non-selective inhibitor of calcium-activated potassium channels (10(-3) M), and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channel (KCa 1.1; 10(-7) M). Iberiotoxin also inhibited the potentiation by kaempferol of sodium nitroprusside-induced relaxations. Kaempferol stimulated an outward-rectifying current in PCASMCs, which was abolished by iberiotoxin. The present results suggest that, in smooth muscle cells of the porcine coronary artery, kaempferol enhanced relaxations caused by endothelium-derived and exogenous NO as well as those due to endothelium-dependent hyperpolarization. This vascular effect of kaempferol involved the activation of KCa 1.1 channels. © 2015 The British Pharmacological Society.

  20. Measurement of Single-top t-channel Production Using ATLAS Data

    CERN Document Server

    Holzbauer, Jenny; Schwienhorst, R; Repko, W; Lapidus, L; Pratt, S

    2012-01-01

    This document reports the measurement of the single-top t-channel cross-section using data from the ATLAS detector, located at the Large Hadron Collider on the border of France and Switzerland. The data used were collected during the first half of 2011, from proton-proton collisions with a 7 TeV center-of-mass collision energy. Single-top is electroweak top-quark production and t-channel is one of the standard model production modes. To isolate this production, selections are applied to find events with a similar final state. A cut-based analysis is used to further isolate the signal using a series of selections in several orthogonal kinematic regions. Finally, a statistical analysis is performed to determine the measured cross-section and the CKM matrix element |Vtb|. The cross-section for top and anti-top production is considered separately and the resulting cross-sections are σ t+ = 59 +18 -16 pb for the positive charge channel and σ t- = 33 +13 -12 pb for the negative charge chan...

  1. Analysis of Simulated and Measured Indoor Channels for mm-Wave Beamforming Applications

    DEFF Research Database (Denmark)

    Karstensen, Anders; Fan, Wei; Zhang, Fengchun

    2018-01-01

    was investigated using both single beam and multiple beams, with two different power allocation schemes applied to multi-beamforming. Channel measurements were performed at 28-30 GHz using a vector network analyzer equipped with a Biconical antenna as the transmit antenna and a rotated horn antenna as the receive...... antenna. 3D ray tracing simulations were carried out in the same replicated propagation environments. Based on measurement and ray tracing simulation data, it is shown that RT-assisted beamforming performs well both for single and multi-beamforming in these two representative indoor propagation...

  2. Four-channel ZnS scintillator measurements of escaping tritons in TFTR

    International Nuclear Information System (INIS)

    Zweben, S.J.

    1988-10-01

    A four-channel scintillation detector capable of measuring tritons, protons, and alphas escaping from a tokamak plasma was operated during the 1986 run period of the Tokamak Fusion Test Reactor (TFTR). Signals consistent with the expected 1 MeV triton behavior have been observed during deuterium operation. Backgrounds associated with neutrons, gammas, and soft x-rays have been evaluated in situ. Such a detector should be capable of measuring escaping alphas during the D/T phase of TFTR. 16 refs., 10 figs

  3. Four-channel ZnS scintillator measurements of escaping tritons in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Zweben, S.J.

    1988-10-01

    A four-channel scintillation detector capable of measuring tritons, protons, and alphas escaping from a tokamak plasma was operated during the 1986 run period of the Tokamak Fusion Test Reactor (TFTR). Signals consistent with the expected 1 MeV triton behavior have been observed during deuterium operation. Backgrounds associated with neutrons, gammas, and soft x-rays have been evaluated in situ. Such a detector should be capable of measuring escaping alphas during the D/T phase of TFTR. 16 refs., 10 figs.

  4. Development of gas-liquid two-phase flow measurement technique in narrow channel. Application of micro wire-mesh sensor to the flow between parallel plates

    International Nuclear Information System (INIS)

    Ito, Daisuke; Kikura, Hiroshige; Aritomi, Masanori

    2009-01-01

    A novel two-phase flow measuring technique based on local electrical conductivity measurement was developed for clarifications of three-dimensional flow structure in gas-liquid two-phase flow in a narrow channel. The measuring method applies the principle of conventional wire-mesh tomography, which can measure the instantaneous void fraction distributions in a cross-section of a flow channel. In this technique, the electrodes are fixed on the inside of the walls facing each other, and the local void fractions were obtained by the electrical conductivity measurement between electrodes arranged on each wall. Therefore, the flow structure and the bubble behavior can be investigated by three-dimensional void fraction distributions in the channel with narrow gap. In this paper, a micro Wire-Mesh Sensor (μWMS) which has the gap of 3 mm was developed, and the instantaneous void fraction distributions were measured. From the measured distributions, three-dimensional bubble distributions were reconstructed, and bubble volumes and bubble velocities were estimated. (author)

  5. Accurate Simulation of 802.11 Indoor Links: A "Bursty" Channel Model Based on Real Measurements

    Directory of Open Access Journals (Sweden)

    Agüero Ramón

    2010-01-01

    Full Text Available We propose a novel channel model to be used for simulating indoor wireless propagation environments. An extensive measurement campaign was carried out to assess the performance of different transport protocols over 802.11 links. This enabled us to better adjust our approach, which is based on an autoregressive filter. One of the main advantages of this proposal lies in its ability to reflect the "bursty" behavior which characterizes indoor wireless scenarios, having a great impact on the behavior of upper layer protocols. We compare this channel model, integrated within the Network Simulator (ns-2 platform, with other traditional approaches, showing that it is able to better reflect the real behavior which was empirically assessed.

  6. High resolution measurement of the velocity profiles of channel flows using the particle image velocimetry technique

    International Nuclear Information System (INIS)

    Nor Azizi Mohamed

    2000-01-01

    The high resolution velocity profiles of a uniform steady channel flow and a flow beneath waves were obtained using the particle image velocimetry (PIV) technique. The velocity profiles for each flow were calculated for both components. It is shown that the profiles obtained are very precise, displaying the point velocities from a few millimeters from the bottom of the channel up to the water surface across the water depth. In the case of the wave-induced flow, the profiles are shown under the respective wave phases and given in a plane representation. High resolution measurement of point velocities in a flow is achievable using PIV and invaluable when applied to a complex flow. (Author)

  7. Measuring thermal conductivity of polystyrene nanowires using the dual-cantilever technique.

    Science.gov (United States)

    Canetta, Carlo; Guo, Samuel; Narayanaswamy, Arvind

    2014-10-01

    Thermal conductance measurements are performed on individual polystyrene nanowires using a novel measurement technique in which the wires are suspended between two bi-material microcantilever sensors. The nanowires are fabricated via electrospinning process. Thermal conductivity of the nanowire samples is found to be between 6.6 and 14.4 W m(-1) K(-1) depending on sample, a significant increase above typical bulk conductivity values for polystyrene. The high strain rates characteristic of electrospinning are believed to lead to alignment of molecular polymer chains, and hence the increase in thermal conductivity, along the axis of the nanowire.

  8. Enhanced electrical properties of oxide semiconductor thin-film transistors with high conductivity thin layer insertion for the channel region

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Cam Phu Thi; Raja, Jayapal; Kim, Sunbo; Jang, Kyungsoo; Le, Anh Huy Tuan; Lee, Youn-Jung; Yi, Junsin, E-mail: junsin@skku.edu

    2017-02-28

    Highlights: • The characteristics of thin film transistors using double active layers are examined. • Electrical characteristics have been improved for the double active layers devices. • The total trap density can be decreased by insert-ion of ultrathin ITO film. - Abstract: This study examined the performance and the stability of indium tin zinc oxide (ITZO) thin film transistors (TFTs) by inserting an ultra-thin indium tin oxide (ITO) layer at the active/insulator interface. The electrical properties of the double channel device (ITO thickness of 5 nm) were improved in comparison with the single channel ITZO or ITO devices. The TFT characteristics of the device with an ITO thickness of less than 5 nm were degraded due to the formation of an island-like morphology and the carriers scattering at the active/insulator interface. The 5 nm-thick ITO inserted ITZO TFTs (optimal condition) exhibited a superior field effect mobility (∼95 cm{sup 2}/V·s) compared with the ITZO-only TFTs (∼34 cm{sup 2}/V·s). The best characteristics of the TFT devices with double channel layer are due to the lowest surface roughness (0.14 nm) and contact angle (50.1°) that result in the highest hydrophicility, and the most effective adhesion at the surface. Furthermore, the threshold voltage shifts for the ITO/ITZO double layer device decreased to 0.80 and −2.39 V compared with 6.10 and −6.79 V (for the ITZO only device) under positive and negative bias stress, respectively. The falling rates of E{sub A} were 0.38 eV/V and 0.54 eV/V for the ITZO and ITO/ITZO bi-layer devices, respectively. The faster falling rate of the double channel devices suggests that the trap density, including interface trap and semiconductor bulk trap, can be decreased by the ion insertion of a very thin ITO film into the ITZO/SiO{sub 2} reference device. These results demonstrate that the double active layer TFT can potentially be applied to the flat panel display.

  9. Measurement of the local void fraction at high pressures in a heating channel

    International Nuclear Information System (INIS)

    Martin, R.

    1969-01-01

    Void fraction measurements were made in two phase flow boiling systems at high pressures in a uniformly heated, rectangular channel with a high aspect ratio. The local void fraction values were calculated from measurements of the absorption of a thin collimated X-ray beam (2 mm x 0.05 mm). The mean void fraction in a horizontal section results from integration of the local values across the section. At a fixed measuring station the quality and- void fraction were varied by changing the heat flux, flow rate and pressure systematically. Two channels were used differing in length and thickness (150.8 cm x 5.3 cm x 0.2 cm and the significant features of this study are: -1) The void fraction measurements are among the first obtained at such high pressure (80 to 140 kg/cm 2 ); -2) In the experimental region under consideration the measurements are systematic and numerous enough to allow accurate interpolations: mass velocity from 50 to 220 g/cm 2 .s, heat flux from 40 to 170 W/cm 2 and calculated steam quality from -0.2 to 0.2; -3) Many tests were performed under local boiling conditions with the mean temperature of the fluid below the saturation temperature; and -4) These results were compared to the predictions of certain models presented in the literature and simple empirical formulae were developed to fit the experimental results. (author) [fr

  10. Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca2+-Activated K+ Channels In Vitro

    Institute of Scientific and Technical Information of China (English)

    Fang Su; An-Chen Guo; Wei-Wei Li; Yi-Long Zhao; Zheng-Yi Qu; Yong-Jun Wang; Qun Wang; Yu-Lan Zhu

    2017-01-01

    Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion;however,the underlying mechanism has not been elucidated.In the present study,we showed that expression of the neuronal large-conductance,Ca2+-activated K+ channel (BKCa) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivatior/reoxygenation (OGD/R) compared with controls.Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R,attenuated the OGD/R-induced elevation of cytosolic Ca2+ levels,and reduced the number of apoptotic neurons.Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax.The protective effect of ethanol preconditioning was antagonized by a BKCa channel inhibitor,paxilline.Inside-out patches in primary neurons also demonstrated the direct activation of the BKCa channel by 10 mmol/L ethanol.The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca2+ and preventing neuronal apoptosis,and this is mediated by BKCa channel activation.

  11. Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca2+-Activated K+ Channels In Vitro.

    Science.gov (United States)

    Su, Fang; Guo, An-Chen; Li, Wei-Wei; Zhao, Yi-Long; Qu, Zheng-Yi; Wang, Yong-Jun; Wang, Qun; Zhu, Yu-Lan

    2017-02-01

    Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca 2+ -activated K + channel (BK Ca ) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) compared with controls. Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca 2+ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol preconditioning was antagonized by a BK Ca channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BK Ca channel by 10 mmol/L ethanol. The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca 2+ and preventing neuronal apoptosis, and this is mediated by BK Ca channel activation.

  12. Sodium Channel Nav1.8 Underlies TTX-Resistant Axonal Action Potential Conduction in Somatosensory C-Fibers of Distal Cutaneous Nerves.

    Science.gov (United States)

    Klein, Amanda H; Vyshnevska, Alina; Hartke, Timothy V; De Col, Roberto; Mankowski, Joseph L; Turnquist, Brian; Bosmans, Frank; Reeh, Peter W; Schmelz, Martin; Carr, Richard W; Ringkamp, Matthias

    2017-05-17

    Voltage-gated sodium (Na V ) channels are responsible for the initiation and conduction of action potentials within primary afferents. The nine Na V channel isoforms recognized in mammals are often functionally divided into tetrodotoxin (TTX)-sensitive (TTX-s) channels (Na V 1.1-Na V 1.4, Na V 1.6-Na V 1.7) that are blocked by nanomolar concentrations and TTX-resistant (TTX-r) channels (Na V 1.8 and Na V 1.9) inhibited by millimolar concentrations, with Na V 1.5 having an intermediate toxin sensitivity. For small-diameter primary afferent neurons, it is unclear to what extent different Na V channel isoforms are distributed along the peripheral and central branches of their bifurcated axons. To determine the relative contribution of TTX-s and TTX-r channels to action potential conduction in different axonal compartments, we investigated the effects of TTX on C-fiber-mediated compound action potentials (C-CAPs) of proximal and distal peripheral nerve segments and dorsal roots from mice and pigtail monkeys ( Macaca nemestrina ). In the dorsal roots and proximal peripheral nerves of mice and nonhuman primates, TTX reduced the C-CAP amplitude to 16% of the baseline. In contrast, >30% of the C-CAP was resistant to TTX in distal peripheral branches of monkeys and WT and Na V 1.9 -/- mice. In nerves from Na V 1.8 -/- mice, TTX-r C-CAPs could not be detected. These data indicate that Na V 1.8 is the primary isoform underlying TTX-r conduction in distal axons of somatosensory C-fibers. Furthermore, there is a differential spatial distribution of Na V 1.8 within C-fiber axons, being functionally more prominent in the most distal axons and terminal regions. The enrichment of Na V 1.8 in distal axons may provide a useful target in the treatment of pain of peripheral origin. SIGNIFICANCE STATEMENT It is unclear whether individual sodium channel isoforms exert differential roles in action potential conduction along the axonal membrane of nociceptive, unmyelinated peripheral nerve

  13. In-situ ionic conductivity measurement of lithium ceramics under high energy heavy ion irradiation

    International Nuclear Information System (INIS)

    Nakazawa, Tetsuya; Noda, Kenji; Ishii, Yoshinobu; Ohno, Hideo; Watanabe, Hitoshi; Matsui, Hisayuki.

    1992-01-01

    To obtain fundamental information regarding the radiation damage in some lithium ceramics, e.g. Li 2 O, Li 4 SiO 4 etc., candidate of breeder materials exposed to severe irradiation environment, an in-situ experiment technique for the ionic conductivity measurement, which allows the specimen temperature control and the beam current monitoring, have been developed. This paper describes the features of an apparatus to measure in situ the ionic conductivity under the irradiation environment and presents some results of ionic conductivity measured for typical ceramic breeders using this apparatus. (J.P.N.)

  14. A New Negative Allosteric Modulator AP14145 for the Study of Small Conductance Calcium-Activated Potassium Channels

    DEFF Research Database (Denmark)

    Simo Vicens, Rafel; Kirchhoff, Jeppe Egedal; Dolce, Bernardo

    2017-01-01

    ) prolongation in anaesthetised rats and a beam walk test was performed in mice to determine acute CNS related effects of the drug. Key results: AP14145 was found to be an equipotent negative allosteric modulator of KCa2.2 and KCa2.3 channels (IC50 = 1.1 ± 0.3 μM L-1). The presence of AP14145 (10 μM L-1......) increased the EC50 of Ca2+ on KCa2.3 from 0.36 ± 0.02 μM L-1 to 1.2 ± 0.1 μM L-1. The inhibitory effect strongly depended on two amino acids, S508 and A533. AP14145 concentration-dependently prolonged AERP in rats. Moreover, AP14145 (10 mg kg-1) did not trigger any apparent CNS effects in mice. Conclusion...... and implications: AP14145 is a negative allosteric modulator of KCa2.2 and KCa2.3 that shifts the calcium dependence of channel activation, an effect strongly dependent on two identified amino acids. AP14145 prolongs AERP in rats and does not trigger any acute CNS effects in mice. The understanding of how KCa2...

  15. Mutating the Conserved Q-loop Glutamine 1291 Selectively Disrupts Adenylate Kinase-dependent Channel Gating of the ATP-binding Cassette (ABC) Adenylate Kinase Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and Reduces Channel Function in Primary Human Airway Epithelia.

    Science.gov (United States)

    Dong, Qian; Ernst, Sarah E; Ostedgaard, Lynda S; Shah, Viral S; Ver Heul, Amanda R; Welsh, Michael J; Randak, Christoph O

    2015-05-29

    The ATP-binding cassette (ABC) transporter cystic fibrosis transmembrane conductance regulator (CFTR) and two other non-membrane-bound ABC proteins, Rad50 and a structural maintenance of chromosome (SMC) protein, exhibit adenylate kinase activity in the presence of physiologic concentrations of ATP and AMP or ADP (ATP + AMP ⇆ 2 ADP). The crystal structure of the nucleotide-binding domain of an SMC protein in complex with the adenylate kinase bisubstrate inhibitor P(1),P(5)-di(adenosine-5') pentaphosphate (Ap5A) suggests that AMP binds to the conserved Q-loop glutamine during the adenylate kinase reaction. Therefore, we hypothesized that mutating the corresponding residue in CFTR, Gln-1291, selectively disrupts adenylate kinase-dependent channel gating at physiologic nucleotide concentrations. We found that substituting Gln-1291 with bulky side-chain amino acids abolished the effects of Ap5A, AMP, and adenosine 5'-monophosphoramidate on CFTR channel function. 8-Azidoadenosine 5'-monophosphate photolabeling of the AMP-binding site and adenylate kinase activity were disrupted in Q1291F CFTR. The Gln-1291 mutations did not alter the potency of ATP at stimulating current or ATP-dependent gating when ATP was the only nucleotide present. However, when physiologic concentrations of ADP and AMP were added, adenylate kinase-deficient Q1291F channels opened significantly less than wild type. Consistent with this result, we found that Q1291F CFTR displayed significantly reduced Cl(-) channel function in well differentiated primary human airway epithelia. These results indicate that a highly conserved residue of an ABC transporter plays an important role in adenylate kinase-dependent CFTR gating. Furthermore, the results suggest that adenylate kinase activity is important for normal CFTR channel function in airway epithelia. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Automatable lipid bilayer formation and ion channel measurement using sessile droplets

    Energy Technology Data Exchange (ETDEWEB)

    Poulos, J L [Librede Inc., Sherman Oaks, CA (United States); Portonovo, S A; Schmidt, J J [Department of Bioengineering, University of California, Los Angeles, Los Angeles (United States); Bang, H, E-mail: schmidt@seas.ucla.ed [School of Mechanical and Aerospace Engineering, Seoul National University (Korea, Republic of)

    2010-11-17

    Artificial lipid bilayer membranes have been used to reconstitute ion channels for scientific and technological applications. Membrane formation has traditionally involved slow, labor intensive processes best suited to small scale laboratory experimentation. We have recently demonstrated a high throughput method of membrane formation using automated liquid-handling robotics. We describe here the integration of membrane formation and measurement with two methods compatible with automation and high throughput liquid-handling robotics. Both of these methods create artificial lipid bilayers by joining lipid monolayers self-assembled at the interface of aqueous and organic phases using sessile aqueous droplets in contact with a measurement electrode; one using a pin tool, commonly employed in high throughput fluid handling assays, and the other using a positive displacement pipette. Membranes formed with both methods were high quality and supported measurement of ion channels at the single molecule level. Full automation of bilayer production and measurement with the positive displacement pipette was demonstrated by integrating it with a motion control platform.

  17. Thermal conductivity measurement of the He-ion implanted layer of W using transient thermoreflectance technique

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Shilian; Li, Yuanfei [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wang, Zhigang [Department of Electronic Engineering, Dalian University of Technology, Dalian 116024 (China); Jia, Yuzhen [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Science and Technology on Reactor Fuel and Materials Laboratory, Nuclear Power Institute of China, Chengdu 610213 (China); Li, Chun [School of Mechanical and Materials Engineering, North China University of Technology, Beijing 100144 (China); Xu, Ben; Chen, Wanqi [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Bai, Suyuan [School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029 (China); Huang, Zhengxing; Tang, Zhenan [Department of Electronic Engineering, Dalian University of Technology, Dalian 116024 (China); Liu, Wei, E-mail: liuw@mail.tsinghua.edu.cn [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-02-15

    Transient thermoreflectance method was applied on the thermal conductivity measurement of the surface damaged layer of He-implanted tungsten. Uniform damages tungsten surface layer was produced by multi-energy He-ion implantation with thickness of 450 nm. Result shows that the thermal conductivity is reduced by 90%. This technique was further applied on sample with holes on the surface, which was produced by the He-implanted at 2953 K. The thermal conductivity decreases to 3% from the bulk value.

  18. Absolute measurement of the thermal conductivity of insulating materials at high temperature

    International Nuclear Information System (INIS)

    Liermann, J.

    1975-01-01

    A device was developed at the CEA for the absolute measurement of the thermal conductivity of insulators. It can operate in controlled atmospheres (air, CO 2 , Ar, He) and between 100 and 1050 deg C [fr

  19. Ionic conductivity of perovskite LaCoO3 measured by oxygen permeation technique

    NARCIS (Netherlands)

    Chen, C.H.; Kruidhof, H.; Bouwmeester, Henricus J.M.; Burggraaf, Anthonie; Burggraaf, A.J.

    1997-01-01

    Oxygen permeation measurement is demonstrated, not only for a mixed oxide ionic and electronic conductor, but also as a new alternative to determine ambipolar conductivities, which can be usually reduced to be partial conductivities (either ionic or electronic). As a model system and an end member

  20. Bulk conductivity of soft surface layers : experimental measurement and electrokinetic implications

    NARCIS (Netherlands)

    Yezek, L.P.

    2005-01-01

    Conductivity measurements were carried out on a family of polyacrylamide-co-sodium acrylate gels cross-linked with N,N¿ -methylenebisacrylamide in a homemade electrokinetic cell. The conductivity data allowed the equilibrium Donnan potential difference between the bulk gel and the bulk electrolyte

  1. Conserved allosteric hot spots in the transmembrane domains of cystic fibrosis transmembrane conductance regulator (CFTR) channels and multidrug resistance protein (MRP) pumps.

    Science.gov (United States)

    Wei, Shipeng; Roessler, Bryan C; Chauvet, Sylvain; Guo, Jingyu; Hartman, John L; Kirk, Kevin L

    2014-07-18

    ATP-binding cassette (ABC) transporters are an ancient family of transmembrane proteins that utilize ATPase activity to move substrates across cell membranes. The ABCC subfamily of the ABC transporters includes active drug exporters (the multidrug resistance proteins (MRPs)) and a unique ATP-gated ion channel (cystic fibrosis transmembrane conductance regulator (CFTR)). The CFTR channel shares gating principles with conventional ligand-gated ion channels, but the allosteric network that couples ATP binding at its nucleotide binding domains (NBDs) with conformational changes in its transmembrane helices (TMs) is poorly defined. It is also unclear whether the mechanisms that govern CFTR gating are conserved with the thermodynamically distinct MRPs. Here we report a new class of gain of function (GOF) mutation of a conserved proline at the base of the pore-lining TM6. Multiple substitutions of this proline promoted ATP-free CFTR activity and activation by the weak agonist, 5'-adenylyl-β,γ-imidodiphosphate (AMP-PNP). TM6 proline mutations exhibited additive GOF effects when combined with a previously reported GOF mutation located in an outer collar of TMs that surrounds the pore-lining TMs. Each TM substitution allosterically rescued the ATP sensitivity of CFTR gating when introduced into an NBD mutant with defective ATP binding. Both classes of GOF mutations also rescued defective drug export by a yeast MRP (Yor1p) with ATP binding defects in its NBDs. We conclude that the conserved TM6 proline helps set the energy barrier to both CFTR channel opening and MRP-mediated drug efflux and that CFTR channels and MRP pumps utilize similar allosteric mechanisms for coupling conformational changes in their translocation pathways to ATP binding at their NBDs. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Electronic energy gap of molecular hydrogen from electrical conductivity measurements at high shock pressures

    Science.gov (United States)

    Nellis, W. J.; Mitchell, A. C.; Mccandless, P. C.; Erskine, D. J.; Weir, S. T.

    1992-01-01

    Electrical conductivities were measured for liquid D2 and H2 shock compressed to pressures of 10-20 GPa (100-200 kbar), molar volumes near 8 cu cm/mol, and calculated temperatures of 2900-4600 K. The semiconducting energy gap derived from the conductivities is 12 eV, in good agreement with recent quasi-particle calculations and with oscillator frequencies measured in diamond-anvil cells.

  3. Thermal conductivity measurements in relation to the geothermal exploration of the Gorleben salt dome

    International Nuclear Information System (INIS)

    Kopietz, J.

    1985-01-01

    The results of thermal conductivity measurements on rock salt and associated structures are presented in this paper. Thermal conductivity data obtained from laboratory measurements on the core material are compared with high-precision temperature gradient logs from the exploration boreholes. This work is part of an extensive investigation into the suitability of the Gorleben salt done in northern Germany as a radioactive waste disposal site

  4. In situ recording of particle network formation in liquids by ion conductivity measurements.

    Science.gov (United States)

    Pfaffenhuber, Christian; Sörgel, Seniz; Weichert, Katja; Bele, Marjan; Mundinger, Tabea; Göbel, Marcus; Maier, Joachim

    2011-09-21

    The formation of fractal silica networks from a colloidal initial state was followed in situ by ion conductivity measurements. The underlying effect is a high interfacial lithium ion conductivity arising when silica particles are brought into contact with Li salt-containing liquid electrolytes. The experimental results were modeled using Monte Carlo simulations and tested using confocal fluorescence laser microscopy and ζ-potential measurements.

  5. Measurement of Critical Heat Flux Using the Transient Inverse Heat Conduction Method in Spray cooling

    International Nuclear Information System (INIS)

    Kim, Yeung Chan

    2016-01-01

    A study on the measurement of critical heat flux using the transient inverse heat conduction method in spray cooling was performed. The inverse heat conduction method estimates the surface heat flux or temperature using a measured interior temperature history. The effects of the measuring time interval and location of temperature measurement on the measurement of critical heat flux were primarily investigated. The following results were obtained. The estimated critical heat flux decreased as the time interval of temperature measurement increased. Meanwhile, the effect of measurement location on critical heat flux was not significant. It was also found, from the experimental results, that the critical superheat increased as the measurement location of thermocouple neared the heat transfer surface.

  6. Measurement of Critical Heat Flux Using the Transient Inverse Heat Conduction Method in Spray cooling

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeung Chan [Andong Nat’l Univ., Andong (Korea, Republic of)

    2016-10-15

    A study on the measurement of critical heat flux using the transient inverse heat conduction method in spray cooling was performed. The inverse heat conduction method estimates the surface heat flux or temperature using a measured interior temperature history. The effects of the measuring time interval and location of temperature measurement on the measurement of critical heat flux were primarily investigated. The following results were obtained. The estimated critical heat flux decreased as the time interval of temperature measurement increased. Meanwhile, the effect of measurement location on critical heat flux was not significant. It was also found, from the experimental results, that the critical superheat increased as the measurement location of thermocouple neared the heat transfer surface.

  7. Magnetic resonance electrical impedance tomography for measuring electrical conductivity during electroporation

    International Nuclear Information System (INIS)

    Kranjc, M; Miklavčič, D; Bajd, F; Serša, I

    2014-01-01

    The electroporation effect on tissue can be assessed by measurement of electrical properties of the tissue undergoing electroporation. The most prominent techniques for measuring electrical properties of electroporated tissues have been voltage–current measurement of applied pulses and electrical impedance tomography (EIT). However, the electrical conductivity of tissue assessed by means of voltage–current measurement was lacking in information on tissue heterogeneity, while EIT requires numerous additional electrodes and produces results with low spatial resolution and high noise. Magnetic resonance EIT (MREIT) is similar to EIT, as it is also used for reconstruction of conductivity images, though voltage and current measurements are not limited to the boundaries in MREIT, hence it yields conductivity images with better spatial resolution. The aim of this study was to investigate and demonstrate the feasibility of the MREIT technique for assessment of conductivity images of tissues undergoing electroporation. Two objects were investigated: agar phantoms and ex vivo liver tissue. As expected, no significant change of electrical conductivity was detected in agar phantoms exposed to pulses of all used amplitudes, while a considerable increase of conductivity was measured in liver tissue exposed to pulses of different amplitudes. (paper)

  8. Information-measurement and control system of the five-channel stellar spectrophotometer

    International Nuclear Information System (INIS)

    Granitskij, L.V.; Bukach, A.B.; Kaplin, Yu.V.; Bondarenko, V.P.; Smirnov, A.I.

    1979-01-01

    The multichannel information-measurement control system of the five-channel stellar spectrophotometer working in photon counting regime is described. The detecting part is synthesized taking into account the principles of multifunctional use of elements of the system. In the part of the photometer scanning mechanism control a discrete drive with the step motor is used. The data are detected on the punched tape, which is convenient for putting them into computer, into a digit printing device with the decimal code or on a diagram tape of the automatic potentiometer

  9. Measurement of top quark polarisation in t-channel single top quark production

    OpenAIRE

    CMS Collaboration

    2015-01-01

    Journal of High Energy Physics 2016.4 (2016): 073 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) Artículo escrito por un elevado número de autores, sólo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiera, y los autores pertenecientes a la UAM A first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based o...

  10. Study of phosphorus implanted and annealed silicon by electrical measurements and ion channeling technique

    CERN Document Server

    Hadjersi, T; Zilabdi, M; Benazzouz, C

    2002-01-01

    We investigated the effect of annealing temperature on the electrical activation of phosphorus implanted into silicon. The measurements performed using spreading resistance, four-point probe and ion channeling techniques have allowed us to establish the existence of two domains of variation of the electrical activation (350-700 deg. C) and (800-1100 deg. C). The presence of reverse annealing and the annihilation of defects have been put in a prominent position in the first temperature range. It has been shown that in order to achieve a complete electrical activation, the annealing temperature must belong to the second domain (800-1100 deg. C).

  11. Multi-channel normal speed gated integrator in the measurement of the laser scattering light energy

    International Nuclear Information System (INIS)

    Yang Dong; Yu Xiaoqi; Hu Yuanfeng

    2005-01-01

    With the method of integration in a limited time, a Multi-channel normal speed gated integrator based on VXI system has been developed for measuring the signals with changeable pulse width in laser scattering light experiment. It has been tested with signal sources in ICF experiment. In tests, the integral nonlinearity between the integral results of the gated integrator and that of an oscilloscope is less than 1%. In the ICF experiments the maximum error between the integral results of the gated integrator and that of oscilloscope is less than 3% of the full scale range of the gated integrator. (authors)

  12. Direct measurement of surface-state conductance by microscopic four-point probe method

    DEFF Research Database (Denmark)

    Hasegawa, S.; Shiraki, I.; Tanikawa, T.

    2002-01-01

    For in situ measurements of local electrical conductivity of well defined crystal surfaces in ultrahigh vacuum, we have developed microscopic four-point probes with a probe spacing of several micrometres, installed in a scanning-electron - microscope/electron-diffraction chamber. The probe...... is precisely positioned on targeted areas of the sample surface by using piezoactuators. This apparatus enables conductivity measurement with extremely high surface sensitivity, resulting in direct access to surface-state conductivity of the surface superstructures, and clarifying the influence of atomic steps...

  13. Measurement and Correlation of the Ionic Conductivity of Ionic Liquid-Molecular Solvent Solutions

    Institute of Scientific and Technical Information of China (English)

    LI,Wen-Jing; HAN,Bu-Xing; TAO,Ran-Ting; ZHANG,Zhao-Fu; ZHANG,Jian-Ling

    2007-01-01

    The ionic conductivity of the solutions formed from 1-n-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) or 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) and different molecular solvents (MSs) were measured at 298.15 K. The molar conductivity of the ionic liquids (ILs) increased dramatically with increasing concentration of the MSs. It was found that the molar conductivity of the IL in the solutions studied in this work could be well correlated by the molar conductivity of the neat ILs and the dielectric constant and molar volume of the MSs.

  14. Measurement of the $t\\bar{t}$ spin correlations and top quark polarization in dileptonic channel

    CERN Document Server

    Khatiwada, Ajeeta

    2017-01-01

    The degree of top polarization and strength of $t\\bar{t}$ correlation are dependent on production dynamics, decay mechanism, and choice of the observables. At the LHC, measurement of the top polarization and spin correlations in $t\\bar{t}$ production is possible through various observables related to the angular distribution of decay leptons. A measurement of differential distribution provides a precision test of the standard model of particle physics and probes for deviations, which could be a sign of new physics. In particular, the phase space for the super-symmetric partner of the top quark can be constrained. Results from the Compact Muon Solenoid (CMS) collaboration for top quark polarization and spin correlation in the dileptonic channel are reviewed briefly in this proceeding. The measurements are obtained using 19.5 fb$^{-1}$ of data collected in pp collisions at the center-of-mass energy of 8 TeV.

  15. Measuring propagation delay over a coded serial communication channel using FPGAs

    International Nuclear Information System (INIS)

    Jansweijer, P.P.M.; Peek, H.Z.

    2011-01-01

    Measurement and control applications are increasingly using distributed system technologies. In such applications, which may be spread over large distances, it is often necessary to synchronize system timing and know with great precision the time offsets between parts of the system. Measuring the propagation delay over a coded serial communication channel using serializer/deserializer (SerDes) functionality in FPGAs is described. The propagation delay between transmitter and receiver is measured with a resolution of a single unit interval (i.e. a serial link running at 3.125 Gbps provides a 320 ps resolution). The technique has been demonstrated to work over 100 km fibre to verify the feasibility for application in the future KM3NeT telescope.

  16. Navigation Signal Disturbances by Multipath Propagation - Scaled Measurements with a Universal Channel Sounder Architecture

    Science.gov (United States)

    Geise, Robert; Neubauer, Bjoern; Zimmer, Georg

    2015-11-01

    The performance of navigation systems is always reduced by unwanted multipath propagation. This is especially of practical importance for airborne navigation systems like the instrument landing system (ILS) or the VHF omni directional radio range (VOR). Nevertheless, the quantitative analysis of corresponding, potentially harmful multipath propagation disturbances is very difficult due to the large parameter space. Experimentally difficulties arise due to very expensive, real scale measurement campaigns and numerical simulation techniques still have shortcomings which are briefly discussed. In this contribution a new universal approach is introduced on how to measure very flexibly multipath propagation effects for arbitrary navigation systems using a channel sounder architecture in a scaled measurement environment. Two relevant scenarios of multipath propagation and the impact on navigation signals are presented. The first describes disturbances of the ILS due to large taxiing aircraft. The other example shows the influence of rotating wind turbines on the VOR.

  17. Electrical conductivity measurement of excised human metastatic liver tumours before and after thermal ablation.

    Science.gov (United States)

    Haemmerich, Dieter; Schutt, David J; Wright, Andrew W; Webster, John G; Mahvi, David M

    2009-05-01

    We measured the ex vivo electrical conductivity of eight human metastatic liver tumours and six normal liver tissue samples from six patients using the four electrode method over the frequency range 10 Hz to 1 MHz. In addition, in a single patient we measured the electrical conductivity before and after the thermal ablation of normal and tumour tissue. The average conductivity of tumour tissue was significantly higher than normal tissue over the entire frequency range (from 4.11 versus 0.75 mS cm(-1) at 10 Hz, to 5.33 versus 2.88 mS cm(-1) at 1 MHz). We found no significant correlation between tumour size and measured electrical conductivity. While before ablation tumour tissue had considerably higher conductivity than normal tissue, the two had similar conductivity throughout the frequency range after ablation. Tumour tissue conductivity changed by +25% and -7% at 10 Hz and 1 MHz after ablation (0.23-0.29 at 10 Hz, and 0.43-0.40 at 1 MHz), while normal tissue conductivity increased by +270% and +10% at 10 Hz and 1 MHz (0.09-0.32 at 10 Hz and 0.37-0.41 at 1 MHz). These data can potentially be used to differentiate tumour from normal tissue diagnostically.

  18. Thermal conductivity and diffusivity of biomaterials measured with self-heated thermistors

    Science.gov (United States)

    Valvano, J. W.; Cochran, J. R.; Diller, K. R.

    1985-05-01

    This paper presents an experimental method to measure the thermal conductivity and thermal diffusivity of biomaterials. Self-heated thermistor probes, inserted into the tissue of interest, are used to deliver heat as well as to monitor the rate of heat removal. An empirical calibration procedure allows accurate thermal-property measurements over a wide range of tissue temperatures. Operation of the instrument in three media with known thermal properties shows the uncertainty of measurements to be about 2%. The reproducibility is 0.5% for the thermal-conductivity measurements and 2% for the thermal-diffusivity measurements. Thermal properties were measured in dog, pig, rabbit, and human tissues. The tissues included kidney, spleen, liver, brain, heart, lung, pancreas, colon cancer, and breast cancer. Thermal properties were measured for 65 separate tissue samples at 3, 10, 17, 23, 30, 37, and 45°C. The results show that the temperature coefficient of biomaterials approximates that of water.

  19. Measuring and assessing the effective in-plane thermal conductivity of lithium iron phosphate pouch cells

    International Nuclear Information System (INIS)

    Bazinski, S.J.; Wang, X.; Sangeorzan, B.P.; Guessous, L.

    2016-01-01

    The objective of this research is to experimentally determine the effective in-plane thermal conductivity of a lithium iron phosphate pouch cell. An experimental setup is designed to treat the battery cell as a straight rectangular fin in natural convection. Thermography and heat sensors were used to collect data that yields the temperature distribution and heat transfer rate of the fin, respectively. One-dimensional fin equations were combined with the experimental data to yield the in-plane thermal conductivity through an iterative process that best-fits the data to the model. The experiment was first calibrated using reference plates of different metals. The fin model predicts the thermal conductivity value well with a correction factor of approximately 7%–9%. Using this experimental method, the in-plane thermal conductivity of the pouch cells is measured at different state of charge (SOC) levels. The in-plane thermal conductivity decreases approximately 0.13 Wm"−"1 °C"−"1 per 10% increase in SOC for the LFP cells. This translates to a 4.2% overall decrease in the thermal conductivity as the cell becomes fully charged. - Highlights: • A method is proposed to measure the in-plane thermal conductivity of a pouch cell. • The thermal conductivity decreases slightly with increase in SOC for the LFP cells. • The fin model predicts the thermal conductivity well with a correction factor.

  20. Electrical conductivity of pyroxene which contains trivalent cations: Laboratory measurements and the lunar temperature profile

    International Nuclear Information System (INIS)

    Huebner, J.S.; Duba, A.; Wiggins, L.B.

    1979-01-01

    Three natural orthopyroxene single crystals, measured in the laboratory over the temperature range 850 0 --1200 0 C, are more than 1/2 order of magnitude more electrically conducting than previously measured crystals. Small concentrations (1--2%) of Al 2 O 3 and Cr 2 O 3 present in these crystals may be responsible for their relatively high conductivity. Such pyroxenes, which contain trivalent elements, are more representative of pyroxenes expected to be present in the lunar mantle than those which have been measured by other investigators. The new conductivity values for pyroxene are responsible for a relatively large bulk conductivity calculated for (polymineralic) lunar mantle assemblages. The results permit a somewhat cooler lunar temperature profile than previously proposed. Such lower profiles, several hundred degrees Celsius below the solidus, are quite consistent with low seismic attenuation and deep moonquakes observed in the lunar mantle

  1. Measurement of thermal conductivity of the oxide coating on autoclaved monel-400

    International Nuclear Information System (INIS)

    Dua, A.K.; George, V.C.; Agarwala, R.P.

    1982-01-01

    Thermal conductivity of the oxide coating on monel-400 has been measured by a direct method. The oxide coating is applied on an electrically conducting wire having stable characteristics. The wire is placed in a constant temperature bath and a constant direct current is passed through it. The wire gets heated and loses heat to the surrounding. Temperature is measured by considering it as a resistance thermometer. A convection heat transfer coefficient, which is difficult to measure experimentally but is involved in the analytical expression for thermal conductivity, is eliminated by connecting a second uncoated wire of a noble metal having similar surface finish as that of the coated wire in series with it. The accuracy of the method is nearly six percent. However, the method is not easily applicable for very thin (thickness <= 1μ), highly porous coatings and materials having relatively large thermal conductivity. (M.G.B.)

  2. A double Gerdien instrument for simultaneous bipolar air conductivity measurements on balloon platforms.

    Science.gov (United States)

    Nicoll, K A; Harrison, R G

    2008-08-01

    A bipolar air conductivity instrument is described for use with a standard disposable meteorological radiosonde package. It is intended to provide electrical measurements at cloud boundaries, where the ratio of the bipolar air conductivities is affected by the presence of charged particles. The sensors are two identical Gerdien-type electrodes, which, through a voltage decay method, measure positive and negative air conductivities simultaneously. Voltage decay provides a thermally stable approach and a novel low current leakage electrometer switch is described which initiates the decay sequence. The radiosonde supplies power and telemetry, as well as measuring simultaneous meteorological data. A test flight using a tethered balloon determined positive (sigma(+)) and negative (sigma(-)) conductivities of sigma(+)=2.77+/-0.2 fS m(-1) and sigma(-)=2.82+/-0.2 fS m(-1), respectively, at 400 m aloft, with sigma(+)sigma(-)=0.98+/-0.04.

  3. An all-polymer micropump based on the conductive polymer poly(3,4-ethylenedioxythiophene) and a polyurethane channel system

    DEFF Research Database (Denmark)

    Hansen, Thomas Steen; West, Keld; Hassager, Ole

    2007-01-01

    An all-polymer micropunlp was realized using the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDT) as the active cODlponent. The pUlnping effect originated fronl an ac potential applied to an aSylnlnetric array of interdigitat.ed electrodes. The PEDT electrodes were fabricated using...... of t.he conducting polylner electrodes by an insulating polYlTIer layer prevented electrode break-down at the cost of puolping efficiency. Continuous punlping for 40 nlin at 20 fJ..,m s-l without detectable pump degradation was delTIOnstrated in this configuration....

  4. Measurement and Estimation of Effective Thermal Conductivity for Sodium based Nanofluid using 3-Omega Method

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Sun Ryung; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of); Kim, Moo Hwan [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The sodium-cooled fast reactor (SFR) is one of generation IV type reactors and has been extensively researched since 1950s. A strong advantage of the SFR is its liquid sodium coolant which is well-known for its superior thermal properties. However, in terms of possible pipe leakage or rupture, a liquid sodium coolant possesses a critical issue due to its high chemical reactivity which leads to fire or explosion. Due to its safety concerns, dispersion of nanoparticles in liquid sodium has been proposed to reduce the chemical reactivity of sodium. In case of sodium based titanium nanofluid (NaTiNF), the chemical reactivity suppression effect when interacting with water has been proved both experimentally and theoretically [1,2]. Suppression of chemical reactivity is critical without much loss of high heat transfer characteristic of sodium. As there is no research conducted for applying 3-omega sensor in liquid metal as well as high temperature liquid, the sensor development is performed for using in NaTiNF as well as effective thermal conductivity model validation. Based on the acquired effective thermal conductivity of NaTiNF, existing effective thermal conductivity models are evaluated. Thermal conductivity measurement is performed for liquid sodium based titanium nanofluid (NaTiNF) through 3-Omega method. The experiment is conducted at three temperature points of 120, 150, and 180 .deg. C for both pure liquid sodium and NaTiNF. By using 3- omega sensor, thermal conductivity measurement of liquid metal can be more conveniently conducted in labscale. Also, its possibility to measure the thermal conductivity of high temperature liquid metal with metallic nanoparticles being dispersed is shown. Unlike other water or oil-based nanofluids, NaTiNF exhibits reduction of thermal conductivity compare with liquid sodium. Various nanofluid models are plotted, and it is concluded that the MSBM which considers interfacial resistance and Brownian motion can be used in predicting

  5. Measurement and Estimation of Effective Thermal Conductivity for Sodium based Nanofluid using 3-Omega Method

    International Nuclear Information System (INIS)

    Oh, Sun Ryung; Park, Hyun Sun; Kim, Moo Hwan

    2016-01-01

    The sodium-cooled fast reactor (SFR) is one of generation IV type reactors and has been extensively researched since 1950s. A strong advantage of the SFR is its liquid sodium coolant which is well-known for its superior thermal properties. However, in terms of possible pipe leakage or rupture, a liquid sodium coolant possesses a critical issue due to its high chemical reactivity which leads to fire or explosion. Due to its safety concerns, dispersion of nanoparticles in liquid sodium has been proposed to reduce the chemical reactivity of sodium. In case of sodium based titanium nanofluid (NaTiNF), the chemical reactivity suppression effect when interacting with water has been proved both experimentally and theoretically [1,2]. Suppression of chemical reactivity is critical without much loss of high heat transfer characteristic of sodium. As there is no research conducted for applying 3-omega sensor in liquid metal as well as high temperature liquid, the sensor development is performed for using in NaTiNF as well as effective thermal conductivity model validation. Based on the acquired effective thermal conductivity of NaTiNF, existing effective thermal conductivity models are evaluated. Thermal conductivity measurement is performed for liquid sodium based titanium nanofluid (NaTiNF) through 3-Omega method. The experiment is conducted at three temperature points of 120, 150, and 180 .deg. C for both pure liquid sodium and NaTiNF. By using 3- omega sensor, thermal conductivity measurement of liquid metal can be more conveniently conducted in labscale. Also, its possibility to measure the thermal conductivity of high temperature liquid metal with metallic nanoparticles being dispersed is shown. Unlike other water or oil-based nanofluids, NaTiNF exhibits reduction of thermal conductivity compare with liquid sodium. Various nanofluid models are plotted, and it is concluded that the MSBM which considers interfacial resistance and Brownian motion can be used in predicting

  6. Development of a Handmade Conductivity Measurement Apparatus and Application to Vegetables and Fruits

    Science.gov (United States)

    Set, Seng; Kita, Masakazu

    2014-01-01

    This paper describes the development of a simple handmade conductivity measurement apparatus based on a Kohlrausch bridge with inexpensive materials. We have examined the reliability of this apparatus with standard solutions and then measured juices of vegetables and fruits as well as a sports drink. Comparisons to total alkali content as…

  7. Estimation of hydraulic conductivities of Yucca Mountain tuffs from sorptivity and water retention measurements

    International Nuclear Information System (INIS)

    Zimmerman, R.W.; Bodvarsson, G.S.

    1995-06-01

    The hydraulic conductivity functions of the matrix rocks at Yucca Mountain, Nevada, are among the most important data needed as input for the site-scale hydrological model of the unsaturated zone. The difficult and time-consuming nature of hydraulic conductivity measurements renders it infeasible to directly measure this property on large numbers of cores. Water retention and sorptivity measurements, however, can be made relatively rapidly. The sorptivity is, in principle, a unique functional of the conductivity and water retention functions. It therefore should be possible to invert sorptivity and water retention measurements in order to estimate the conductivity; the porosity is the only other parameter that is required for this inversion. In this report two methods of carrying out this inversion are presented, and are tested against a limited data set that has been collected by Flint et al. at the USGS on a set of Yucca Mountain tuffs. The absolute permeability is usually predicted by both methods to within an average error of about 0.5 - 1.0 orders of magnitude. The discrepancy appears to be due to the fact that the water retention curves have only been measured during drainage, whereas the imbibition water retention curve is the one that is relevant to sorptivity measurements. Although the inversion methods also yield predictions of the relative permeability function, there are yet no unsaturated hydraulic conductivity data against which to test these predictions

  8. Measurements of thermal diffusivity, specific heat capacity and thermal conductivity with LFA 447 apparatus

    DEFF Research Database (Denmark)

    Zajas, Jan Jakub; Heiselberg, Per

    The LFA 447 can be successfully used for measurements of thermal diffusivity, specific heat and thermal conductivity of various samples. It is especially useful when determining the properties of materials on a very small scale. The matrix measurement mode allows for determining the local...... that the heat losses from both samples during the measurement are similar. Finally, the leveling of the samples is very important. Very small discrepancies can cause a massive error in the derivation of specific heat capacity and, as a result, thermal conductivity....

  9. Determination of microturbulence enhanced electron collisionality in magnetized coaxial accelerator channels by direct magnetic field measurement

    International Nuclear Information System (INIS)

    Black, D.C.; Mayo, R.M.; Caress, R.W.

    1997-01-01

    A miniature magnetic probe array, consisting of 10 spatially separated coils, has been used to obtain profile information on the time varying magnetic field within the 2.54 cm wide flow channel of the coaxial plasma source experiment (CPS-1) [R. M. Mayo et al., Plasma Sources Sci. Technol. 4, 47 (1995)]. The magnetic field data have been used, together with a resistive, Hall magnetohydrodynamic (MHD) model of applied field distortion by the flowing plasma, to obtain estimates of the microturbulent enhancement to electron collisionality within the CPS-1 flow channel. These measurements provide direct experimental evidence of anomalous electron collisionality, a previously predicted effect in these devices. The anomaly parameter, a=ν an /ν cl , determined both from the distortion of contours of constant magnetic flux, and from local B θ and B z measurements scales with the classical electron magnetization parameter (Ω cl =ω ce /ν e cl ), indicating that collisionality plays a strong role in determining the level of anomalous transport in the plasma. When this anomaly parameter scaling is cast in terms of the ratio ν e cl /ω lh , it is found that the resistivity enhancement scales with ν e cl /ω lh , and becomes significant at ν e cl /ω lh ≤1, suggesting that a lower hybrid drift instability may be the responsible mechanism for enhanced transport. copyright 1997 American Institute of Physics

  10. Note: Development of a microfabricated sensor to measure thermal conductivity of picoliter scale liquid samples.

    Science.gov (United States)

    Park, Byoung Kyoo; Yi, Namwoo; Park, Jaesung; Kim, Dongsik

    2012-10-01

    This paper presents a thermal analysis device, which can measure thermal conductivity of picoliter scale liquid sample. We employ the three omega method with a microfabricated AC thermal sensor with nanometer width heater. The liquid sample is confined by a micro-well structure fabricated on the sensor surface. The performance of the instrument was verified by measuring the thermal conductivity of 27-picoliter samples of de-ionized (DI) water, ethanol, methanol, and DI water-ethanol mixtures with accuracies better than 3%. Furthermore, another analytical scheme allows real-time thermal conductivity measurement with 5% accuracy. To the best of our knowledge, this technique requires the smallest volume of sample to measure thermal property ever.

  11. Optical reading of field-effect transistors by phase-space absorption quenching in a single InGaAs quantum well conducting channel

    Science.gov (United States)

    Chemla, D. S.; Bar-Joseph, I.; Klingshirn, C.; Miller, D. A. B.; Kuo, J. M.

    1987-03-01

    Absorption switching in a semiconductor quantum well by electrically varying the charge density in the quantum well conducting channel of a selectively doped heterostructure transistor is reported for the first time. The phase-space absorption quenching (PAQ) is observed at room temperature in an InGaAs/InAlAs grown on InP FET, and it shows large absorption coefficient changes with relatively broad spectral bandwidth. This PAQ is large enough to be used for direct optical determination of the logic state of the FET.

  12. Studies on the under ground heating in greenhouse. Measuring of thermal conductivity of soil

    Energy Technology Data Exchange (ETDEWEB)

    Iwao, Toshio; Takeyama, Koichi

    1987-12-21

    The underground heating system is an effective method of heating a greenhouse, because the system controls directly the temperature of soil near the roots. The thermal conductivity of soil was measured by the steady-state method, and the heat transfer characteristics in soil were examined in this study. In measuring the thermal conductivity through experiments, firstly the thermal conductivity of a reference plate was measured by the steady-state method, then on the basis of the above mentioned result, the thermal conuctivity of soil was obtained by the comparative method. Toyoura standard sands with particle size of 0.21-0.25mm were used as the sample. As the experiment result, the relations between the thermal conductivity of the reference plate (glass) and temperature was made clear, furthermore through the measurements using these relations, it was clarified that the apparent thermal conductivity is influenced by soil water content. It seems that the difference between the apparent thermal conductivity and the real one is caused mainly by a migration of latent heat with a migration of steam. (10 figs, 7 refs)

  13. Apelin-13 inhibits large-conductance Ca2+-activated K+ channels in cerebral artery smooth muscle cells via a PI3-kinase dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Amit Modgil

    Full Text Available Apelin-13 causes vasoconstriction by acting directly on APJ receptors in vascular smooth muscle (VSM cells; however, the ionic mechanisms underlying this action at the cellular level remain unclear. Large-conductance Ca(2+-activated K(+ (BKCa channels in VSM cells are critical regulators of membrane potential and vascular tone. In the present study, we examined the effect of apelin-13 on BK(Ca channel activity in VSM cells, freshly isolated from rat middle cerebral arteries. In whole-cell patch clamp mode, apelin-13 (0.001-1 μM caused concentration-dependent inhibition of BK(Ca in VSM cells. Apelin-13 (0.1 µM significantly decreased BK(Ca current density from 71.25 ± 8.14 pA/pF to 44.52 ± 7.10 pA/pF (n=14 cells, P<0.05. This inhibitory effect of apelin-13 was confirmed by single channel recording in cell-attached patches, in which extracellular application of apelin-13 (0.1 µM decreased the open-state probability (NPo of BK(Ca channels in freshly isolated VSM cells. However, in inside-out patches, extracellular application of apelin-13 (0.1 µM did not alter the NPo of BK(Ca channels, suggesting that the inhibitory effect of apelin-13 on BKCa is not mediated by a direct action on BK(Ca. In whole cell patches, pretreatment of VSM cells with LY-294002, a PI3-kinase inhibitor, markedly attenuated the apelin-13-induced decrease in BK(Ca current density. In addition, treatment of arteries with apelin-13 (0.1 µM significantly increased the ratio of phosphorylated-Akt/total Akt, indicating that apelin-13 significantly increases PI3-kinase activity. Taken together, the data suggest that apelin-13 inhibits BK(Ca channel via a PI3-kinase-dependent signaling pathway in cerebral artery VSM cells, which may contribute to its regulatory action in the control of vascular tone.

  14. Matrix diffusion studies by electrical conductivity methods. Comparison between laboratory and in-situ measurements

    International Nuclear Information System (INIS)

    Ohlsson, Y.; Neretnieks, I.

    1998-01-01

    Traditional laboratory diffusion experiments in rock material are time consuming, and quite small samples are generally used. Electrical conductivity measurements, on the other hand, provide a fast means for examining transport properties in rock and allow measurements on larger samples as well. Laboratory measurements using electrical conductivity give results that compare well to those from traditional diffusion experiments. The measurement of the electrical resistivity in the rock surrounding a borehole is a standard method for the detection of water conducting fractures. If these data could be correlated to matrix diffusion properties, in-situ diffusion data from large areas could be obtained. This would be valuable because it would make it possible to obtain data very early in future investigations of potentially suitable sites for a repository. This study compares laboratory electrical conductivity measurements with in-situ resistivity measurements from a borehole at Aespoe. The laboratory samples consist mainly of Aespoe diorite and fine-grained granite and the rock surrounding the borehole of Aespoe diorite, Smaaland granite and fine-grained granite. The comparison shows good agreement between laboratory measurements and in-situ data

  15. Enhanced K+-channel-mediated endothelium-dependent local and conducted dilation of small mesenteric arteries from ApoE−/− mice

    Science.gov (United States)

    Beleznai, Timea; Takano, Hiromichi; Hamill, Claire; Yarova, Polina; Douglas, Gillian; Channon, Keith; Dora, Kim

    2011-01-01

    Aims Agonists that evoke smooth muscle cell hyperpolarization have the potential to stimulate both local and conducted dilation. We investigated whether the endothelium-dependent vasodilators acetylcholine (ACh) and SLIGRL stimulated conducted dilation and whether this was altered by deficiency in apolipoprotein E (ApoE−/−). Methods and results Isolated mesenteric arteries were cannulated, pressurized, and precontracted with phenylephrine. Agonists were either added to the bath to study local dilation or were restricted to one end of arteries to study conducted dilation. An enhanced sensitivity to both ACh and SLIGRL was observed in mesenteric arteries from ApoE−/− mice compared with wild-type controls. Inhibition of nitric oxide (NO) synthase blocked ACh responses, but had no effect on maximum dilation to SLIGRL. SLIGRL increased endothelial cell Ca2+, hyperpolarized smooth muscle cells, and fully dilated arteries. The NO-independent dilation to SLIGRL was blocked with high [KCl] or Ca2+-activated K+-channel blockers. The hyperpolarization and dilation to SLIGRL passed through the artery to at least 2.5 mm upstream. The conducted dilation was not affected by a deficit in ApoE and could also be stimulated by ACh, suggesting NO itself could stimulate conducted dilation. Conclusion In small mesenteric arteries of ApoE−/− mice, NO-independent dilation is enhanced. Since both NO-dependent and -independent pathways can stimulate local and conducted dilation, the potential for reducing vascular resistance is improved in these vessels. PMID:21690174

  16. Optical Performance of Breadboard Amon-Ra Imaging Channel Instrument for Deep Space Albedo Measurement

    Directory of Open Access Journals (Sweden)

    Won Hyun Park

    2007-03-01

    Full Text Available The AmonRa instrument, the primary payload of the international EARTHSHINE mission, is designed for measurement of deep space albedo from L1 halo orbit. We report the optical design, tolerance analysis and the optical performance of the breadborad AmonRa imaging channel instrument optimized for the mission science requirements. In particular, an advanced wavefront feedback process control technique was used for the instrumentation process including part fabrication, system alignment and integration. The measured performances for the complete breadboard system are the RMS 0.091 wave(test wavelength: 632.8 nm in wavefront error, the ensquared energy of 61.7%(in 14 μ m and the MTF of 35.3%(Nyquist frequency: 35.7 mm^{-1} at the center field. These resulting optical system performances prove that the breadboard AmonRa instrument, as built, satisfies the science requirements of the EARTHSHINE mission.

  17. Purity of Gaussian states: Measurement schemes and time evolution in noisy channels

    International Nuclear Information System (INIS)

    Paris, Matteo G.A.; Illuminati, Fabrizio; Serafini, Alessio; De Siena, Silvio

    2003-01-01

    We present a systematic study of the purity for Gaussian states of single-mode continuous variable systems. We prove the connection of purity to observable quantities for these states, and show that the joint measurement of two conjugate quadratures is necessary and sufficient to determine the purity at any time. The statistical reliability and the range of applicability of the proposed measurement scheme are tested by means of Monte Carlo simulated experiments. We then consider the dynamics of purity in noisy channels. We derive an evolution equation for the purity of general Gaussian states both in thermal and in squeezed thermal baths. We show that purity is maximized at any given time for an initial coherent state evolving in a thermal bath, or for an initial squeezed state evolving in a squeezed thermal bath whose asymptotic squeezing is orthogonal to that of the input state

  18. Field intercomparison of channel master ADCP with RiverSonde Radar for measuring river discharge

    Science.gov (United States)

    Spain, P.; Marsden, R.; Barrick, D.; Teague, C.; Ruhl, C.

    2005-01-01

    The RiverSonde radar makes non-contact measurement of a horizontal swath of surface velocity across a river section. This radar, which has worked successfully at several rivers in the Western USA, has shown encouraging correlation with simultaneous measurements of average currents at one level recorded by an acoustic travel-time system. This work reports a field study intercomparing data sets from a 600 kHz Channel Master ADCP with the RiverSonde radar. The primary goal was to begin to explore the robustness of the radar data as a reliable index of discharge. This site Is at Three Mile Slough in Northern California, USA. The larger intent of the work is to examine variability in space and time of the radar's surface currents compared with subsurface flows across the river section. Here we examine data from a couple of periods with strong winds. ?? 2005 IEEE.

  19. Measurement of the thermal conductivity of thin insulating anisotropic material with a stationary hot strip method

    International Nuclear Information System (INIS)

    Jannot, Yves; Degiovanni, Alain; Félix, Vincent; Bal, Harouna

    2011-01-01

    This paper presents a method dedicated to the thermal conductivity measurement of thin insulating anisotropic materials. The method is based on three hot-strip-type experiments in which the stationary temperature is measured at the center of the hot strip. A 3D model of the heat transfer in the system is established and simulated to determine the validity of a 2D transfer hypothesis at the center of the hot strip. A simplified 2D model is then developed leading to the definition of a geometrical factor calculable from a polynomial expression. A very simple calculation method enabling the estimation of the directional thermal conductivities from the three stationary temperature measurements and from the geometrical factor is presented. The uncertainties on each conductivity are estimated. The method is then validated by measurements on polyethylene foam and Ayous (anistropic low-density tropical wood); the estimated values of the thermal conductivities are in good agreement with the values estimated using the hot plate and the flash method. The method is finally applied on a thin super-insulating fibrous material for which no other method is able to measure the in-plane conductivity

  20. Development of the interfacial area concentration measurement method using a five sensor conductivity probe

    International Nuclear Information System (INIS)

    Euh, Dong Jin; Yun, Byong Jo; Song, Chul Hwa; Kwon, Tae Soon; Chung, Moon Ki; Lee, Un Chul

    2000-01-01

    The interfacial area concentration(IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The IAE can be measured by a local conductivity probe method that uses the difference of conductivity between water and air/steam. The number of sensors in the conductivity probe may be differently chosen by considering the flow regime of two-phase flow. The four sensor conductivity probe method predicts the IAC without any assumptions of the bubble shape. The local IAC can be obtained by measuring the three dimensional velocity vector elements at the measuring point, and the directional cosines of the sensors. The five sensor conductivity probe method proposed in this study is based on the four sensor probe method. With the five sensor probe, the local IAC for a given referred measuring area of the probe can be predicted more exactly than the four sensor prober. In this paper, the mathematical approach of the five sensor probe method for measuring the IAC is described, and a numerical simulation is carried out for ideal cap bubbles of which the sizes and locations are determined by a random number generator

  1. Experimental Measurement and Numerical Modeling of the Effective Thermal Conductivity of TRISO Fuel Compacts

    International Nuclear Information System (INIS)

    Folsom, Charles

    2015-01-01

    Accurate modeling capability of thermal conductivity of tristructural-isotropic (TRISO) fuel compacts is important to fuel performance modeling and safety of Generation IV reactors. To date, the effective thermal conductivity (ETC) of tristructural-isotropic (TRISO) fuel compacts has not been measured directly. The composite fuel is a complicated structure comprised of layered particles in a graphite matrix. In this work, finite element modeling is used to validate an analytic ETC model for application to the composite fuel material for particle-volume fractions up to 40%. The effect of each individual layer of a TRISO particle is analyzed showing that the overall ETC of the compact is most sensitive to the outer layer constituent. In conjunction with the modeling results, the thermal conductivity of matrix-graphite compacts and the ETC of surrogate TRISO fuel compacts have been successfully measured using a previously developed measurement system. The ETC of the surrogate fuel compacts varies between 50-30 W m -1 K -1 over a temperature range of 50-600°C. As a result of the numerical modeling and experimental measurements of the fuel compacts, a new model and approach for analyzing the effect of compact constituent materials on ETC is proposed that can estimate the fuel compact ETC with approximately 15-20% more accuracy than the old method. Using the ETC model with measured thermal conductivity of the graphite matrix-only material indicate that, in the composite form, the matrix material has a much greater thermal conductivity, which is attributed to the high anisotropy of graphite thermal conductivity. Therefore, simpler measurements of individual TRISO compact constituents combined with an analytic ETC model, will not provide accurate predictions of overall ETC of the compacts emphasizing the need for measurements of composite, surrogate compacts.

  2. Different role of TTX-sensitive voltage-gated sodium channel (NaV 1) subtypes in action potential initiation and conduction in vagal airway nociceptors.

    Science.gov (United States)

    Kollarik, M; Sun, H; Herbstsomer, R A; Ru, F; Kocmalova, M; Meeker, S N; Undem, B J

    2018-04-15

    The action potential initiation in the nerve terminals and its subsequent conduction along the axons of afferent nerves are not necessarily dependent on the same voltage-gated sodium channel (Na V 1) subunits. The action potential initiation in jugular C-fibres within airway tissues is not blocked by TTX; nonetheless, conduction of action potentials along the vagal axons of these nerves is often dependent on TTX-sensitive channels. This is not the case for nodose airway Aδ-fibres and C-fibres, where both action potential initiation and conduction is abolished by TTX or selective Na V 1.7 blockers. The difference between the initiation of action potentials within the airways vs. conduction along the axons should be considered when developing Na V 1 blocking drugs for topical application to the respiratory tract. The action potential (AP) initiation in the nerve terminals and its subsequent AP conduction along the axons do not necessarily depend on the same subtypes of voltage-gated sodium channels (Na V 1s). We evaluated the role of TTX-sensitive and TTX-resistant Na V 1s in vagal afferent nociceptor nerves derived from jugular and nodose ganglia innervating the respiratory system. Single cell RT-PCR was performed on vagal afferent neurons retrogradely labelled from the guinea pig trachea. Almost all of the jugular neurons expressed the TTX-sensitive channel Na V 1.7 along with TTX-resistant Na V 1.8 and Na V 1.9. Tracheal nodose neurons also expressed Na V 1.7 but, less frequently, Na V 1.8 and Na V 1.9. Na V 1.6 were expressed in ∼40% of the jugular and 25% of nodose tracheal neurons. Other Na V 1 α subunits were only rarely expressed. Single fibre recordings were made from the vagal nodose and jugular nerve fibres innervating the trachea or lung in the isolated perfused vagally-innervated preparations that allowed for selective drug delivery to the nerve terminal compartment (AP initiation) or to the desheathed vagus nerve (AP conduction). AP initiation in

  3. A low cost apparatus for measuring the xylem hydraulic conductance in plants

    Directory of Open Access Journals (Sweden)

    Luciano Pereira

    2012-01-01

    Full Text Available Plant yield and resistance to drought are directly related to the efficiency of the xylem hydraulic conductance and the ability of this system to avoid interrupting the flow of water. In this paper we described in detail the assembling of an apparatus proposed by TYREE et al. (2002, and its calibration, as well as low cost adaptations that make the equipment accessible for everyone working in this research area. The apparatus allows measuring the conductance in parts of roots or shoots (root ramifications or branches, or in the whole system, in the case of small plants or seedlings. The apparatus can also be used to measure the reduction of conductance by embolism of the xylem vessels. Data on the hydraulic conductance of eucalyptus seedlings obtained here and other reports in the literature confirm the applicability of the apparatus in physiological studies on the relationship between productivity and water stress.

  4. Experimental measurements of the eddy current signal due to a flawed, conducting half space

    International Nuclear Information System (INIS)

    Long, S.A.; Toomsawasdi, S.; Zaman, A.J.M.

    1984-01-01

    This chapter reports on an experimental investigation in which the change in impedance of a practical multi-turn eddy current coil near a conducting half space is measured as a function of the conductivity and the lift-off distance. The results are compared in a qualitative fashion with the analytical results for a single-turn coil. Measurements are also made of the change in impedance due to a small void in the conducting half space as a function of both its depth and radial position. The results indicate that, at least in a qualitative fashion, the precisely derived analytical solutions adequately predict the general behavior of the change in complex impedance of an eddy current coil above a conducting ground plane as a function of lift-off distance. It is determined that the effect of a sub-surface void on the change in inductance of the test coil correlates well with theoretical calculations

  5. A heat source probe for measuring thermal conductivity in waste rock dumps

    International Nuclear Information System (INIS)

    Blackford, M.G.; Harries, J.R.

    1985-10-01

    The development and use of a heat source probe to measure the thermal conductivity of the material in a waste rock dump is described. The probe releases heat at a constant rate into the surrounding material and the resulting temperature rise is inversely related to the thermal conductivity. The probe was designed for use in holes in the dump which are lined with 50 mm i.d. polyethylene liners. The poor thermal contact between the probe and the liner and the unknown conductivity of the backfill material around the liner necessitated long heating and cooling times (>10 hours) to ensure that the thermal conductivity of the dump material was being measured. Temperature data acquired in the field were analysed by comparing them with temperatures calculated using a two-dimensional cylindrical model of the probe and surrounding material, and the heat transfer code HEATRAN

  6. Measurements of Regolith Simulant Thermal Conductivity Under Asteroid and Mars Surface Conditions

    Science.gov (United States)

    Ryan, A. J.; Christensen, P. R.

    2017-12-01

    Laboratory measurements have been necessary to interpret thermal data of planetary surfaces for decades. We present a novel radiometric laboratory method to determine temperature-dependent thermal conductivity of complex regolith simulants under rough to high vacuum and across a wide range of temperatures. This method relies on radiometric temperature measurements instead of contact measurements, eliminating the need to disturb the sample with thermal probes. We intend to determine the conductivity of grains that are up to 2 cm in diameter and to parameterize the effects of angularity, sorting, layering, composition, and eventually cementation. We present the experimental data and model results for a suite of samples that were selected to isolate and address regolith physical parameters that affect bulk conductivity. Spherical glass beads of various sizes were used to measure the effect of size frequency distribution. Spherical beads of polypropylene and well-rounded quartz sand have respectively lower and higher solid phase thermal conductivities than the glass beads and thus provide the opportunity to test the sensitivity of bulk conductivity to differences in solid phase conductivity. Gas pressure in our asteroid experimental chambers is held at 10^-6 torr, which is sufficient to negate gas thermal conduction in even our coarsest of samples. On Mars, the atmospheric pressure is such that the mean free path of the gas molecules is comparable to the pore size for many regolith particulates. Thus, subtle variations in pore size and/or atmospheric pressure can produce large changes in bulk regolith conductivity. For each sample measured in our martian environmental chamber, we repeat thermal measurement runs at multiple pressures to observe this behavior. Finally, we present conductivity measurements of angular basaltic simulant that is physically analogous to sand and gravel that may be present on Bennu. This simulant was used for OSIRIS-REx TAGSAM Sample Return

  7. Novel method to classify hemodynamic response obtained using multi-channel fNIRS measurements into two groups: Exploring the combinations of channels

    Directory of Open Access Journals (Sweden)

    Hiroko eIchikawa

    2014-07-01

    Full Text Available Near-infrared spectroscopy (NIRS in psychiatric studies has widely demonstrated that cerebral hemodynamics differs among psychiatric patients. Recently we found that children with attention attention-deficit / hyperactivity disorder (ADHD and children with autism spectrum disorders (ASD showed different hemodynamic responses to their own mother’s face. Based on this finding, we may be able to classify their hemodynamic data into two those groups and predict which diagnostic group an unknown participant belongs to. In the present study, we proposed a novel statistical method for classifying the hemodynamic data of these two groups. By applying a support vector machine (SVM, we searched the combination of measurement channels at which the hemodynamic response differed between the two groups; ADHD and ASD. The SVM found the optimal subset of channels in each data set and successfully classified the ADHD data from the ASD data. For the 24-dimentional hemodynamic data, two optimal subsets classified the hemodynamic data with 84% classification accuracy while the subset contains all 24 channels classified with 62% classification accuracy. These results indicate the potential application of our novel method for classifying the hemodynamic data into two groups and revealing the combinations of channels that efficiently differentiate the two groups.

  8. Measurement of thermal conductivity of uranium metal using transient plane source technique

    International Nuclear Information System (INIS)

    Subramanian, G.G.S.; Bapuji, T.; Panneerselvam, G.; Antony, M.P.; Nagarajan, K.

    2012-01-01

    Thermo physical properties of fuel, cladding and structural materials play a significant role in the reactor operation. Thermal conductivity is one of the most important physical properties of the fuel which determines the maximum linear heat rating of the fuel in a reactor. As part of this study, the thermal conductivity of uranium metal was measured using a transient plane source (TPS) by Hot-disc method

  9. Bulk velocity measurements by video analysis of dye tracer in a macro-rough channel

    International Nuclear Information System (INIS)

    Ghilardi, T; Franca, M J; Schleiss, A J

    2014-01-01

    Steep mountain rivers have hydraulic and morphodynamic characteristics that hinder velocity measurements. The high spatial variability of hydraulic parameters, such as water depth (WD), river width and flow velocity, makes the choice of a representative cross-section to measure the velocity in detail challenging. Additionally, sediment transport and rapidly changing bed morphology exclude the utilization of standard and often intrusive velocity measurement techniques. The limited technical choices are further reduced in the presence of macro-roughness elements, such as large, relatively immobile boulders. Tracer tracking techniques are among the few reliable methods that can be used under these conditions to evaluate the mean flow velocity. However, most tracer tracking techniques calculate bulk flow velocities between two or more fixed cross-sections. In the presence of intense sediment transport resulting in an important temporal variability of the bed morphology, dead water zones may appear in the few selected measurement sections. Thus a technique based on the analysis of an entire channel reach is needed in this study. A dye tracer measurement technique in which a single camcorder visualizes a long flume reach is described and developed. This allows us to overcome the problem of the presence of dead water zones. To validate this video analysis technique, velocity measurements were carried out on a laboratory flume simulating a torrent, with a relatively gentle slope of 1.97% and without sediment transport, using several commonly used velocity measurement instruments. In the absence of boulders, salt injections, WD and ultrasonic velocity profiler measurements were carried out, along with dye injection technique. When boulders were present, dye tracer technique was validated only by comparison with salt tracer. Several video analysis techniques used to infer velocities were developed and compared, showing that dye tracking is a valid technique for bulk velocity

  10. A conceptual model of channel choice : measuring online and offline shopping value perceptions

    NARCIS (Netherlands)

    Broekhuizen, Thijs L.J.; Jager, Wander

    2004-01-01

    This study tries to understand how consumers evaluate channels for their purchasing. Specifically, it develops a conceptual model that addresses consumer value perceptions of using the Internet versus the traditional (physical) channel. Previous research showed that perceptions of price, product

  11. Thermal conductivity measurements in porous mixtures of methane hydrate and quartz sand

    Science.gov (United States)

    Waite, W.F.; deMartin, B.J.; Kirby, S.H.; Pinkston, J.; Ruppel, C.D.

    2002-01-01

    Using von Herzen and Maxwell's needle probe method, we measured thermal conductivity in four porous mixtures of quartz sand and methane gas hydrate, with hydrate composing 0, 33, 67 and 100% of the solid volume. Thermal conductivities were measured at a constant methane pore pressure of 24.8 MPa between -20 and +15??C, and at a constant temperature of -10??C between 3.5 and 27.6 MPa methane pore pressure. Thermal conductivity decreased with increasing temperature and increased with increasing methane pore pressure. Both dependencies weakened with increasing hydrate content. Despite the high thermal conductivity of quartz relative to methane hydrate, the largest thermal conductivity was measured in the mixture containing 33% hydrate rather than in hydrate-free sand. This suggests gas hydrate enhanced grain-to-grain heat transfer, perhaps due to intergranular contact growth during hydrate synthesis. These results for gas-filled porous mixtures can help constrain thermal conductivity estimates in porous, gas hydrate-bearing systems.

  12. Effects of electric field and Coriolis force on electrohydrodynamic stability of poorly conducting couple stress parallel fluid flow in a channel

    International Nuclear Information System (INIS)

    Shankar, B.M.; Rudraiah, N.

    2013-01-01

    The linear stability of electrohydrodynamic poorly conducting couple stress viscous parallel fluid flow in a channel is studied in the presence of a non-uniform transverse electric field and Coriolis force using energy method and supplemented with Galerkin Technique. The sufficient condition for stability is obtained for sufficiently small values of the Reynolds number, R e . From this condition we show that strengthening or weakening of the stability criterion is dictated by the values of the strength of electric field, the coefficient of couple stress fluid and independent of Taylor number. In particular, it is shown that the interaction of electric field with couple stress is more effective in stabilizing the poorly conducting couple stress fluid compared to that in an ordinary Newtonian viscous fluid. (author)

  13. Direct measurement of thermal conductivity in solid iron at planetary core conditions.

    Science.gov (United States)

    Konôpková, Zuzana; McWilliams, R Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F

    2016-06-02

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action. Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo.

  14. Flexible probe for measuring local conductivity variations in Li-ion electrode films

    Science.gov (United States)

    Hardy, Emilee; Clement, Derek; Vogel, John; Wheeler, Dean; Mazzeo, Brian

    2018-04-01

    Li-ion battery performance is governed by electronic and ionic properties of the battery. A key metric that characterizes Li-ion battery cell performance is the electronic conductivity of the electrodes, which are metal foils with thin coatings of electrochemically active materials. To accurately measure the spatial variation of electronic conductivity of these electrodes, a micro-four-line probe (μ4LP) was designed and used to non-destructively measure the properties of commercial-quality Li-ion battery films. This previous research established that the electronic conductivity of film electrodes is not homogeneous throughout the entirety of the deposited film area. In this work, a micro-N-line probe (μNLP) and a flexible micro-flex-line probe (μFLP) were developed to improve the non-destructive micro-scale conductivity measurements that we can take. These devices were validated by comparing test results to that of the predecessor, the micro-four-line probe (μ4LP), on various commercial-quality Li-ion battery electrodes. Results show that there is significant variation in conductivity on a millimeter and even micrometer length scale through the electrode film. Compared to the μ4LP, the μNLP and μFLP also introduce additional measurement configuration possibilities, while providing a more robust design. Researchers and manufacturers can use these probes to identify heterogeneity in their electrodes during the fabrication process, which will lead to the development of better batteries.

  15. Microphase separation and the formation of ion conductivity channels in poly(ionic liquid)s: A coarse-grained molecular dynamics study

    Science.gov (United States)

    Weyman, Alexander; Bier, Markus; Holm, Christian; Smiatek, Jens

    2018-05-01

    We study generic properties of poly(ionic liquid)s (PILs) via coarse-grained molecular dynamics simulations in bulk solution and under confinement. The influence of different side chain lengths on the spatial properties of the PIL systems and on the ionic transport mechanism is investigated in detail. Our results reveal the formation of apolar and polar nanodomains with increasing side chain length in good agreement with previous results for molecular ionic liquids. The ion transport numbers are unaffected by the occurrence of these domains, and the corresponding values highlight the potential role of PILs as single-ion conductors in electrochemical devices. In contrast to bulk behavior, a pronounced formation of ion conductivity channels in confined systems is initiated in close vicinity to the boundaries. We observe higher ion conductivities in these channels for increasing PIL side chain lengths in comparison with bulk values and provide an explanation for this effect. The appearance of these domains points to an improved application of PILs in modern polymer electrolyte batteries.

  16. Resveratrol Protects Against Ultraviolet A-Mediated Inhibition of the Phagocytic Function of Human Retinal Pigment Epithelial Cells Via Large-Conductance Calcium-Activated Potassium Channels

    Directory of Open Access Journals (Sweden)

    Shwu-Jiuan Sheu

    2009-07-01

    Full Text Available This study was undertaken to examine the protective effect of resveratrol on human retinal pigment epithelial (RPE cell phagocytosis against ultraviolet irradiation damage. Cultured RPE cells were exposed to ultraviolet A (UVA, 20 minutes irradiation, and treated with meclofenamic acid (30μM, 20 minutes, paxilline (100 μM, 20 minutes or resveratrol (10μM, 20 minutes. Meclofenamic acid and resveratrol were given after exposure to UVA. Pretreatment with meclofenamic acid, resveratrol or paxilline before UVA irradiation was also performed. Fluorescent latex beads were then fed for 4 hours and the phagocytotic function was assessed by flow cytometry. UVA irradiation inhibited the phagocytic function of human RPE cells. The large-conductance calcium-activated potassium channel activator meclofenamic acid ameliorated the damage caused by UVA irradiation. Pretreatment with resveratrol acid also provided protection against damage caused by UVA. Posttreatment with meclofenamic acid offered mild protection, whereas resveratrol did not. In conclusion, the red wine flavonoid resveratrol ameliorated UVA-mediated inhibition of human RPE phagocytosis. The underlying mechanism might involve the large-conductance calcium-activated potassium channels.

  17. Time Resolved Tomographic PIV Measurements of Rough-Wall Turbulent Channel Flow

    Science.gov (United States)

    Miorini, Rinaldo; Zhang, Cao; Katz, Joseph

    2013-11-01

    Time resolved tomographic PIV is used to study flow structures in the outer region of a rough-wall turbulent boundary layer, focusing on imprints of the roughness on the outer layer. Measurements are performed in a transparent channel installed in the JHU optically index matched facility. The roughness consists of pyramids with height, k = 0.46 mm, and wavelength, λ = 3.2 mm, satisfying h/k = 55 (h = 25.4 mm is the channel half-height), k + = 64 and Re = 40000. The TPIV setup consists of four high-speed cameras operating at 3 kHz, which view the sample volume through acrylic prisms. The flow field is illuminated by an Nd:YLF laser. Following enhancement, calibration, and reconstruction, 643 voxels interrogation volumes with 0.75 overlap provide 3D velocity fields with spacing of 0.5883 mm3. Formation and transport of near-wall 3D U-shaped vortex structures, with base in front of the pyramids, and quasi-streamwise legs extending between pyramid crest lines are evident from the data. Extended streamwise regions of high wall-normal vorticity appear ``latched'' to the roughness elements close to the wall, but are transported downstream at higher elevations. Also evident are traveling streamwise low velocity streaks, which cover many roughness elements. Sponsored by NSF CBET and ONR.

  18. Developments of quad channel pulse height analyzer for radon/thoron measurement

    International Nuclear Information System (INIS)

    Ashokkumar, P.; Raman, Anand; Babu, D.A.R.; Sharma, D.N.; Topkar, Anita; Mayya, Y.S.

    2011-01-01

    Radon and thoron are naturally occurring noble radioactive gases, the exposure to which has a linear relationship to lung cancer risk. This paper describes development of an automated Radon/Thoron measurement system using an indigenously developed silicon PIN diode. This system employs the 8051 core architecture based Si-lab microcontroller (C-8051F340) integrated with LCD display, hex key pad, non volatile flash memory besides I/O ports interfaced with humidity-temperature sensors and air sampling pump. Air is sampled through a dehumidifier by using a software controlled dc pump. The positively charged progeny atoms are electro statically collected over the detector surface and the deposited radioactivity is assessed by alpha pulse height discrimination technique. The ionization charges produced due to the interaction of alpha particles in the charge depletion region of the diode which is reverse biased at 40V are collected and measured. The measurement circuit uses a charge sensitive preamplifier developed around a low noise opamp IC. The pulses are further processed through a spectroscopy amplifier to obtain distinct pulse height levels for four of the alpha emitting progenies of Rn and Tn namely 210 Po, 214 Po, 216 Po and 212 Po. These signals are input to the quad channel analyzer which provides four individual TTL pulses corresponding to four nuclides mentioned above. The analyzer outputs are processed by the microcontroller module to obtain the Rn/Tn concentration in Bq/M 3 . This portable system stores one week hourly individual channel data along with the corresponding Rn/Tn concentrations, temperature, humidity and can be transferred to pc. Preliminary studies have indicated that sensitivity as low as 0.50 cph/Bq.m -3 can be achieved by this system. (author)

  19. Device for measuring high temperature heat conductivity of solids and melts

    International Nuclear Information System (INIS)

    Magomedov, Ya.B.; Gadzhiev, G.G.

    1990-01-01

    A modification of a device for measuring heat conductivity by a compensation method when a thermocouple with gadolinium sulfide being used is suggested. Such a device has less error of measurement (8%), wider interval of working temperatures (300-1600K) and it permits to investigate the material in the wide range of heat conductivity values (0.5-30 W/(mxK)). The stainless steel 12Kh18N10T, lanthanum sulfide and melted quartz were used for the device calibration. The results obtained and the literature data on these materials agree well between each other

  20. Electrical conduction through surface superstructures measured by microscopic four-point probes

    DEFF Research Database (Denmark)

    Hasegawa, S.; Shiraki, I.; Tanabe, F.

    2003-01-01

    For in-situ measurements of the local electrical conductivity of well-defined crystal surfaces in ultra-high vacuum, we have developed two kinds of microscopic four-point probe methods. One involves a "four-tip STM prober," in which four independently driven tips of a scanning tunneling microscope...... (STM) are used for measurements of four-point probe conductivity. The probe spacing can be changed from 500 nm to 1 mm. The other method involves monolithic micro-four-point probes, fabricated on silicon chips, whose probe spacing is fixed around several mum. These probes are installed in scanning...

  1. The measurement of the vertical component of hydraulic conductivity in single cased and uncased boreholes

    International Nuclear Information System (INIS)

    Black, J.H.; Noy, D.J.; Brightman, M.A.

    1986-11-01

    The project summarised in the paper aimed to assess the different existing methods of measuring vertical hydraulic conductivity in single boreholes by carrying out some actual field testing. The measurements are relevant to the disposal of radioactive waste into argillaceous rocks, where the primary geological barrier to potential leachate migration is the mudrock. Also the prime parameter of interest in the assessment of mudrocks is the vertical component of hydraulic conductivity. A description of the methods of test analysis and interpretation is given. The experimental programme for open borehole testing and cased borehole testing is described, along with the practical and theoretical considerations. (U.K.)

  2. Instrumentation-related uncertainty of reflectance and transmittance measurements with a two-channel spectrophotometer.

    Science.gov (United States)

    Peest, Christian; Schinke, Carsten; Brendel, Rolf; Schmidt, Jan; Bothe, Karsten

    2017-01-01

    Spectrophotometers are operated in numerous fields of science and industry for a variety of applications. In order to provide confidence for the measured data, analyzing the associated uncertainty is valuable. However, the uncertainty of the measurement results is often unknown or reduced to sample-related contributions. In this paper, we describe our approach for the systematic determination of the measurement uncertainty of the commercially available two-channel spectrophotometer Agilent Cary 5000 in accordance with the Guide to the expression of uncertainty in measurements. We focus on the instrumentation-related uncertainty contributions rather than the specific application and thus outline a general procedure which can be adapted for other instruments. Moreover, we discover a systematic signal deviation due to the inertia of the measurement amplifier and develop and apply a correction procedure. Thereby we increase the usable dynamic range of the instrument by more than one order of magnitude. We present methods for the quantification of the uncertainty contributions and combine them into an uncertainty budget for the device.

  3. Interpretation of measured data and the resolution analysis of the RTP 4-channel pulsed radar

    International Nuclear Information System (INIS)

    Pavlo, P.

    1993-01-01

    The resolution of a 4-channel pulsed radar being built at Rijnhuisen for the RTP tokamak is analyzed. The achievable resolution mainly depends on the accuracy of the time-of-flight measurements and the number of sampling frequencies; since the technological solution and the configuration have already been set, emphasis is put on interpretation of the measured data (the inversion problem) and minimization of the overall error. For this purpose, a specific neural network - the Multi Layer Perceptron (MLP) - has successfully been applied. Central density in the range of 0.2-0.6 x 10 20 m -3 was considered, i.e., one above the critical density for all four frequencies but not so high as to restrict the measurements to just the edge of the plasma. By balancing the inversion error and the time measurement error, for a wide class of density profiles the overall error in estimating the reflection point position of between 0.72 cm (for the lowest frequency) and 0.52 cm (for the highest frequency) root mean square was obtained, assuming an RMS error of 70 ps in the time of flight measurements. This is probably much better than what could be obtained by the Abel transform. Moreover, mapping with the MLP is considerably faster, and it should be considered for routine multichannel pulsed radar data processing. (author) 2 tabs., 4 figs., 6 refs

  4. Using the coolant temperature noise for measuring the flow rate in the RBMK technological channels

    International Nuclear Information System (INIS)

    Selivanov, V.M.; Karlov, N.P.; Martynov, A.D.; Prostyakov, V.V.; Lysikov, B.V.; Kuznetsov, B.A.; Pallagi, D.; Khorani, Sh.; Khargitai, T.; Tezher, Sh.

    1983-01-01

    The problems are considered connected with the possibility of using thermometric correlation method to measure the coolant flow rate in the RBMK reactor technological channels. The main attention is paid to the study of the physical nature of the coolant temperature pulsations and to estimation of the effect of parameters of the primary thermaelectrical converter (TEC) on the results of measurements. In the process of reactor inspections made using the thermometric correlation flowmeter of a special design, the temperature noise distribution in the points of flow rate measurement is studied, the noise intensity and physical nature are determined, as well as the effect of different TEC parameters (TEC inertia and base distance between them) on the measurement accuracy. On the basis of the analysis of the effect on the results of the TEC thermal inertia measured value divergence, tausub(α) and transport time, tau sub(T), a conclusion is made on the necessity of choosing the base distance between TEC with tausub(T)>tausub(d)

  5. Development of a direct push based in-situ thermal conductivity measurement system

    Science.gov (United States)

    Chirla, Marian Andrei; Vienken, Thomas; Dietrich, Peter; Bumberger, Jan

    2016-04-01

    Heat pump systems are commonly utilized in Europe, for the exploitation of the shallow geothermal potential. To guarantee a sustainable use of the geothermal heat pump systems by saving resources and minimizing potential negative impacts induced by temperature changes within soil and groundwater, new geothermal exploration methods and tools are required. The knowledge of the underground thermal properties is a necessity for a correct and optimum design of borehole heat exchangers. The most important parameter that indicates the performance of the systems is thermal conductivity of the ground. Mapping the spatial variability of thermal conductivity, with high resolution in the shallow subsurface for geothermal purposes, requires a high degree of technical effort to procure adequate samples for thermal analysis. A collection of such samples from the soil can disturb sample structure, so great care must be taken during collection to avoid this. Factors such as transportation and sample storage can also influence measurement results. The use of technologies like Thermal Response Test (TRT) require complex mechanical and electrical systems for convective heat transport in the subsurface and longer monitoring times, often three days. Finally, by using thermal response tests, often only one integral value is obtained for the entire coupled subsurface with the borehole heat exchanger. The common thermal conductivity measurement systems (thermal analyzers) can perform vertical thermal conductivity logs only with the aid of sample procurement, or by integration into a drilling system. However, thermal conductivity measurements using direct push with this type of probes are not possible, due to physical and mechanical limitations. Applying vertical forces using direct push technology, in order to penetrate the shallow subsurface, can damage the probe and the sensors systems. The aim of this study is to develop a new, robust thermal conductivity measurement probe, for direct

  6. Space charge effect measurements for a multi-channel ionization chamber used for synchrotron radiation

    International Nuclear Information System (INIS)

    Nasr, Amgad

    2012-01-01

    In vivo coronary angiography is one of the techniques used to investigate the heart diseases, by using catheter to inject a contrast medium of a given absorption coefficient into the heart vessels. Taking X-ray images produced by X-ray tube or synchrotron radiation for visualizing the blood in the coronary arteries. As the synchrotron radiation generated by the relativistic charged particle at the bending magnets, which emits high intensity photons in comparison with the X-ray tube. The intensity of the synchrotron radiation is varies with time. However for medical imaging it's necessary to measure the incoming intensity with the integrated time. The thesis work includes building a Multi-channel ionization chamber which can be filled with noble gases N 2 , Ar and Xe with controlled inner pressure up to 30 bar. This affects the better absorption efficiency in measuring the high intensity synchrotron beam fluctuation. The detector is a part of the experimental setup used in the k-edge digital subtraction angiography project, which will be used for correcting the angiography images taken by another detector at the same time. The Multi-channel ionization chamber calibration characteristics are measured using 2 kW X-ray tube with molybdenum anode with characteristic energy of 17.44 keV. According to the fast drift velocity of the electrons relative to the positive ions, the electrons will be collected faster at the anode and will induce current signals, while the positive ions is still drifting towards the cathode. However the accumulation of the slow ions inside the detector disturbs the homogeneous applied electric field and leads to what is known a space charge effect. In this work the space charge effect is measured with very high synchrotron photons intensity from EDR beam line at BESSYII. The strong attenuation in the measured amplitude signal occurs when operating the chamber in the recombination region. A plateau is observed at the amplitude signal when

  7. Space charge effect measurements for a multi-channel ionization chamber used for synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nasr, Amgad

    2012-07-18

    In vivo coronary angiography is one of the techniques used to investigate the heart diseases, by using catheter to inject a contrast medium of a given absorption coefficient into the heart vessels. Taking X-ray images produced by X-ray tube or synchrotron radiation for visualizing the blood in the coronary arteries. As the synchrotron radiation generated by the relativistic charged particle at the bending magnets, which emits high intensity photons in comparison with the X-ray tube. The intensity of the synchrotron radiation is varies with time. However for medical imaging it's necessary to measure the incoming intensity with the integrated time. The thesis work includes building a Multi-channel ionization chamber which can be filled with noble gases N{sub 2}, Ar and Xe with controlled inner pressure up to 30 bar. This affects the better absorption efficiency in measuring the high intensity synchrotron beam fluctuation. The detector is a part of the experimental setup used in the k-edge digital subtraction angiography project, which will be used for correcting the angiography images taken by another detector at the same time. The Multi-channel ionization chamber calibration characteristics are measured using 2 kW X-ray tube with molybdenum anode with characteristic energy of 17.44 keV. According to the fast drift velocity of the electrons relative to the positive ions, the electrons will be collected faster at the anode and will induce current signals, while the positive ions is still drifting towards the cathode. However the accumulation of the slow ions inside the detector disturbs the homogeneous applied electric field and leads to what is known a space charge effect. In this work the space charge effect is measured with very high synchrotron photons intensity from EDR beam line at BESSYII. The strong attenuation in the measured amplitude signal occurs when operating the chamber in the recombination region. A plateau is observed at the amplitude signal when

  8. 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.

  9. Physical outcome measures for conductive and mixed hearing loss treatment: A systematic review.

    Science.gov (United States)

    Johansson, M L; Tysome, J R; Hill-Feltham, P; Hodgetts, W E; Ostevik, A; McKinnon, B J; Monksfield, P; Sockalingam, R; Wright, T

    2018-05-07

    The number of potential options for rehabilitation of patients with conductive or mixed hearing loss is continually expanding. To be able to inform patients and other stakeholders there is a need to identify and develop patient-centred outcomes for treatment of hearing loss. To identify outcome measures in the physical core area used when reporting the outcome after treatment of conductive and mixed hearing loss in adult patients. Systematic review. Systematic review of literature related to reported physical outcome measures after treatment of mixed or conductive hearing loss without restrictions regarding type of intervention, treatment or device. Any measure reporting the physical outcome after treatment or intervention of mixed or conductive hearing loss was sought and categorised. The physical outcomes measures that had been extracted were then grouped into domains. The literature search resulted in the identification of 1,434 studies, of which 153 were selected for inclusion in the review. The majority (57%) of papers reported results from middle ear surgery, with the remainder reporting results from either bone conduction hearing devices or middle ear implants. Outcomes related to complications were categorised into 17 domains, whereas outcomes related to treatment success was categorised in 22 domains. The importance of these domains to patients and other stakeholders needs to be further explored in order to establish which of these domains are most relevant to interventions for conductive or mixed hearing loss. This will allow us to then assess which outcomes measures are most suitable for inclusion in the core set This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  10. The difference in the thermal conductivity of nanofluids measured by different methods and its rationalization

    Directory of Open Access Journals (Sweden)

    Aparna Zagabathuni

    2016-12-01

    Full Text Available A suspension of particles below 100 nm in size, usually termed as nanofluid, often shows a notable enhancement in thermal conductivity, when measured by the transient hot-wire method. In contrast, when the conductivity of the same nanofluid is measured by the laser flash method, the enhancement reported is about one order of magnitude lower. This difference has been quantitatively resolved for the first time on the basis of the collision-mediated heat transfer model for nanofluids proposed earlier by our research group. Based on the continuum simulation coupled with stochastic analysis, the present theoretical prediction agrees well with the experimental observations from different measuring methods reported in the literature, and fully accounts for the different results from the two measuring methods mentioned above. This analysis also gives an indication that the nanofluids are unlikely to be effective for heat transfer in microchannels.

  11. The difference in the thermal conductivity of nanofluids measured by different methods and its rationalization.

    Science.gov (United States)

    Zagabathuni, Aparna; Ghosh, Sudipto; Pabi, Shyamal Kumar

    2016-01-01

    A suspension of particles below 100 nm in size, usually termed as nanofluid, often shows a notable enhancement in thermal conductivity, when measured by the transient hot-wire method. In contrast, when the conductivity of the same nanofluid is measured by the laser flash method, the enhancement reported is about one order of magnitude lower. This difference has been quantitatively resolved for the first time on the basis of the collision-mediated heat transfer model for nanofluids proposed earlier by our research group. Based on the continuum simulation coupled with stochastic analysis, the present theoretical prediction agrees well with the experimental observations from different measuring methods reported in the literature, and fully accounts for the different results from the two measuring methods mentioned above. This analysis also gives an indication that the nanofluids are unlikely to be effective for heat transfer in microchannels.

  12. Method and Apparatus for Measuring Thermal Conductivity of Small, Highly Insulating Specimens

    Science.gov (United States)

    Miller, Robert A (Inventor); Kuczmarski, Maria A (Inventor)

    2013-01-01

    A method and apparatus for the measurement of thermal conductivity combines the following capabilities: 1) measurements of very small specimens; 2) measurements of specimens with thermal conductivity on the same order of that as air; and, 3) the ability to use air as a reference material. Care is taken to ensure that the heat flow through the test specimen is essentially one-dimensional. No attempt is made to use heated guards to minimize the flow of heat from the hot plate to the surroundings. Results indicate that since large correction factors must be applied to account for guard imperfections when specimen dimensions are small, simply measuring and correcting for heat from the heater disc that does not flow into the specimen is preferable.

  13. Thermal conductivity measurement of HTS tapes and stacks for current lead applications

    International Nuclear Information System (INIS)

    Schwarz, Michael; Weiss, Klaus-Peter; Heller, Reinhard; Fietz, Walter H.

    2009-01-01

    The use of high-temperature-superconductors (HTS) within current leads offers a high potential to save cooling-power. The principle of HTS current leads is well established, e.g. for particle accelerators (LHC-CERN) but also on the commercial sector, which offer HTS current leads ready for use in small scale magnets and magnets systems. Future fusion machines currently under construction like ITER, W7-X or JT-60SA also will use HTS current leads. At the moment the standard material for HTS current leads is a Bi 2 Sr 2 Ca 2 Cu 3 O x (BSCCO)-AgAu composite tape. The common way to receive high current capacity current leads is to form stacks by sintering or soldering these tapes together. The solder changes the thermal conductivity of the stacks compared to the single tape in the temperature range from 4 K to 60 K. To estimate the heat flux from the warm environment to the cold application the measurement of the thermal conductivity of the soldered stack is mandatory. Therefore the thermal conductivity of stacks with different number of tapes is investigated. To measure the thermal conduction in the current flow direction, the axial heat flow method is used. Combining these results with FEM simulations gives the possibility to estimate the thermal conductivity normal to the flat tape plane. The resulting anisotropic thermal conductivity can be used to model the behaviour of the HTS tape under thermal disturbances more accurately.

  14. Measurements of MIMO Indoor Channels at 1800 MHz with Multiple Indoor and Outdoor Base Stations

    Directory of Open Access Journals (Sweden)

    Jaldén Niklas

    2007-01-01

    Full Text Available This paper proposes several configurations for multiple base stations in indoor MIMO systems and compares their performance. The results are based on channel measurements realized with a MIMO testbed. The receiver was moved along several routes and floors on an office building. Both outdoor and indoor locations are considered for the transmitters or base stations, which allow the analysis of not only indoor but also outdoor-to-indoor environment. The use of 2 base stations with different system level combinations of the two is analyzed. We show that the configuration with base station selection provides almost as good performance as a full water-filling scheme when the 2 base stations are placed at different locations. Also the spatial correlation properties for the different configurations are analyzed and the importance of considering path loss when evaluating capacity is highlighted.

  15. On-line adaptive line frequency noise cancellation from a nuclear power measuring channel

    Directory of Open Access Journals (Sweden)

    Qadir Javed

    2011-01-01

    Full Text Available On-line software for adaptively canceling 50 Hz line frequency noise has been designed and tested at Pakistan Research Reactor 1. Line frequency noise causes much problem in weak signals acquisition. Sometimes this noise is so dominant that original signal is totally corrupted. Although notch filter can be used for eliminating this noise, but if signal of interest is in close vicinity of 50 Hz, then original signal is also attenuated and hence overall performance is degraded. Adaptive noise removal is a technique which could be employed for removing line frequency without degrading the desired signal. In this paper line frequency noise has been eliminated on-line from a nuclear power measuring channel. The adaptive LMS algorithm has been used to cancel 50 Hz noise. The algorithm has been implemented in labVIEW with NI 6024 data acquisition card. The quality of the acquired signal has been improved much as can be seen in experimental results.

  16. RBS channeling measurement of damage annealing in InAs/AlSb HEMT structures

    International Nuclear Information System (INIS)

    Hallén, Anders; Moschetti, Giuseppe

    2014-01-01

    Electrical isolation of InAs/AlSb high electron mobility transistors has been achieved by the ion implantation isolation technique. The multilayered structures are grown by molecular beam epitaxy on GaAs substrates. The optimal isolation is provided by damaging patterned areas by 100 keV Ar ions implanted at room temperature using fluence of 2 × 10 15 cm −2 , and then annealing the samples in 365 °C for 30 min. The damage build-up and annealing is studied by channeling Rutherford backscattering spectrometry (RBS) and compared to sheet resistance measurements. Only a low level of damage annealing can be seen in RBS for the post-implant annealed samples, but for Ar fluence higher than 2 × 10 14 cm −2 , a strong electrical resistivity increase can still be achieved

  17. Measurement of DC electrical conductivity of alumina during spallation-neutron irradiation

    International Nuclear Information System (INIS)

    Farnum, E.H.; Clinard, F.W. Jr.; Kennedy, J.C. III; Sommer, W.F.; Dammeyer, M.D.

    1993-01-01

    An irradiation experiment was carried out during the summer of 1992 at the Los Alamos Spallation Radiation Effects Facility (LASREF). In situ measurements of electrical conductivity in alumina, sapphire and mineral-insulated electrical cables were made at 640 degrees C, 590 degrees C and 400 degrees C. Both DC and AC (100 Hz to 1 MHz) measurements were made to fluence of approximately 3 x 10 23 n/m 2 . Optical absorption from 200 nm to 800 nm was measured in pure silica - and OH-doped silica-core optical fibers during the irradiation. A large number of passive samples were included in the irradiation, some at the furnace temperatures and some at ambient temperature. This report describes preliminary analysis of the DC conductivity measurements. The AC measurements are analyzed in the companion report. All samples are being recovered for post-irradiation examination as this report is being written in May, 1993. Final analysis of the conductivity data awaits the results of measured fluence from activation foils and will be published at ICFRM-6

  18. Cross-section measurement of single-top t-channel production at ATLAS

    International Nuclear Information System (INIS)

    Herrberg-Schubert, Ruth Hedwig Margarete

    2014-01-01

    This study presents the cross-section measurement of electroweak single-top quark production in the t-channel with a semi-leptonically decaying top quark. The study is based on 4.7 fb -1 of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider in the year 2011. Selected events contain two highly energetic jets, one of which is identified as originating from a beauty quark, as well as a highly energetic electron or muon and transverse missing energy. The case of three and four jets is also considered but eventually discarded since their inclusion degrades the precision of the result. The event reconstruction is done with a chi-square-based kinematic fit using W boson and top quark mass constraints. The chi-square value in each event serves to classify the event as a signal-like or background-like process. The cross-section is extracted by performing a template-based maximum likelihood fit to the distribution that displays the best discriminatory power: This distribution is chosen such that the shape differences between signal and background with respect to the typical forward light jet kinematics of the t-channel are exploited. An observation of the single-top t-channel process with a significance of 5.7 σ is obtained, and the cross-section is measured to be 111 +29 -28 pb. Assuming vertical stroke V tb vertical stroke 2 >> vertical stroke V td vertical stroke 2 + vertical stroke V ts vertical stroke 2 as well as a (V-A), CP-conserving interaction, and allowing for the presence of anomalous couplings at the W-t-b vertex, the associated value of the CKM matrix element times an anomalous form factor is determined as vertical stroke V tb f L 1 vertical stroke =1.30 +0.13 -0.16 . The corresponding lower limit in the standard model scenario 0≤ vertical stroke V tb vertical stroke ≤1 amounts to 0.77 tb vertical stroke at 95% confidence level.

  19. Multi-channel Waveform Sampling ASIC for radiation detection and measurement

    International Nuclear Information System (INIS)

    Shimazoe, K.; Takahashi, H.; Yeom, J.Y.; Furumiya, T.; Ohi, J.

    2013-01-01

    We have designed and fabricated a 16-channel Waveform Sampling ASIC for radiation detection and measurement. Waveform sampling is very important for the pulse shape analysis and discrimination, which is often used in radiation detection to discriminate different radiations such as alpha, beta and gamma rays. One channel of the fabricated ASIC consists of a charge-sensitive preamplifier, a VGA (Variable Gain Amplifier), an ADC (Analog to Digital Converter) and digital circuits. The preamplifier converts the current signal to the voltage signal, and the VGA amplifies the signal to appropriate level for the ADC. The ADC was designed to digitize the waveform with a frequency of 100 MHz and a resolution of 6bits. Digital circuits consist of a free-running ADC and a multiplexer which were designed to convert a digitized 100 MHz/6bit signal to a 200 MHz/3bit one, which is effective for the reduction of the number and for the achievement of the high integration in one chip. This chip was designed and fabricated with 0.35 μm CMOS technology by ROHM and the size of the ASIC is 4.9 mm by 4.9 mm. The design concept and some experimental results are shown in this paper. -- Highlights: ► Waveform sampling (WS) ASIC is newly developed for pulse shape discrimination. ► WS ASIC can be used for radiation measurement and discrimination. ► WS ASIC is fabricated by submicron CMOS technology for 5 mm × 5 mm area. ► WS ASIC achieves high integration and can be used in very limited space

  20. Thermal conductivity of Al–Cu–Mg–Si alloys: Experimental measurement and CALPHAD modeling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cong [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German cooperation group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Du, Yong, E-mail: yong-du@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German cooperation group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Liu, Shuhong; Liu, Yuling [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German cooperation group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Sundman, Bo. [INSTN, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France)

    2016-07-10

    Highlights: • The thermal conductivities of Al–x wt% Cu (x = 1, 3, 5, 15 and 30) and Al–y wt% Si (y = 2, 12.5 and 20) alloys were determined. • The reported thermal conductivities of Al–Cu–Mg–Si system were critically reviewed. • The CALPHAD approach was applied for the modeling of thermal conductivity. • The applicability of CALPHAD technique in the modeling of thermal conductivity was discussed. - Abstract: In the present work, the thermal conductivities and microstructure of Al–x wt% Cu (x = 1, 3, 5, 15 and 30) and Al–y wt% Si (y = 2, 12.5 and 20) alloys were investigated by using laser-flash method, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Besides, a CALPHAD (CALculation of PHAse Diagram) approach to evaluate the thermal conductivity of Al–Cu–Mg–Si system was performed. The numerical models for the thermal conductivity of pure elements and stoichiometric phases were described as polynomials, and the coefficients were optimized via PARROT module of Thermal-Calc software applied to the experimental data. The thermal conductivity of (Al)-based solid solutions was described by using Redlich–Kister interaction parameters. For alloys in two-phase region, the interface scattering parameter was proposed in the modeling to describe the impediment of interfaces on the heat transfer. Finally, a set of self-consistent parameters for the description of thermal conductivity in Al–Cu–Mg–Si system was obtained, and comprehensive comparisons between the calculated and measured thermal conductivities show that the experimental information is satisfactorily accounted for by the present modeling.

  1. Development of an apparatus for measuring the thermal conductivity of irradiated or non-irradiated graphite

    International Nuclear Information System (INIS)

    Bocquet, M.; Micaud, G.

    1962-01-01

    An apparatus was developed for measuring the thermal conductivity coefficient K of irradiated or non-irradiated graphite. The measurement of K at around room temperature with an accuracy of about 6% is possible. The study specimen is placed in a vacuum between a hot and a cold source which create a temperature gradient ΔΘ/ Δx in the steady state. The amount of heat transferred, Q, is deduced from the electrical power dissipated at the hot source, after allowing for heat losses. The thermal conductivity coefficient is defined as: K = Q/S. Δx/ΔΘ, S being the cross section of the sample. Systematic studies have made it possible to determine the mean values of the thermal conductivity. (authors) [fr

  2. Measurement of Apparent Thermal Conductivity of JSC-1A Under Ambient Pressure

    Science.gov (United States)

    Yuan, Zeng-Guang; Kleinhenz, Julie E.

    2011-01-01

    The apparent thermal conductivity of JSC-1A lunar regolith simulant was measured experimentally using a cylindrical apparatus. Eleven thermocouples were embedded in the simulant bed to obtain the steady state temperature distribution at various radial, axial, and azimuthal locations. The high aspect ratio of a cylindrical geometry was proven to provide a one-dimensional, axisymmetric temperature field. A test series was performed at atmospheric pressure with varying heat fluxes. The radial temperature distribution in each test fit a logarithmic function, indicating a constant thermal conductivity throughout the soil bed. However, thermal conductivity was not constant between tests at different heat fluxes. This variation is attributed to stresses created by thermal expansion of the simulant particles against the rigid chamber wall. Under stress-free conditions (20 deg C), the data suggest a temperature independent apparent conductivity of 0.1961 +/- 0.0070 W/m/ deg C

  3. Measured Temperature Dependence of the cos-phi Conductance in Josephson Tunnel Junctions

    DEFF Research Database (Denmark)

    Sørensen, O. H.; Mygind, Jesper; Pedersen, Niels Falsig

    1977-01-01

    The temperature dependence of the cosϕ conductance in Sn-O-Sn Josephson tunnel junctions has been measured just below the critical temperature, Tc. From the resonant microwave response at the junction plasma frequency as the temperature is decreased from Tc it is deduced that the amplitude of the...

  4. Using Conductivity Measurements to Determine the Identities and Concentrations of Unknown Acids: An Inquiry Laboratory Experiment

    Science.gov (United States)

    Smith, K. Christopher; Garza, Ariana

    2015-01-01

    This paper describes a student designed experiment using titrations involving conductivity measurements to identify unknown acids as being either HCl or H[subscript 2]SO[subscript 4], and to determine the concentrations of the acids, thereby improving the utility of standard acid-base titrations. Using an inquiry context, students gain experience…

  5. Optical approach to thermopower and conductivity measurements in thin-film semiconductors

    International Nuclear Information System (INIS)

    Dersch, H.; Amer, N.M.

    1984-01-01

    An optical beam deflection technique is applied to measure the Joule and Peltier heat generated by electric currents through thin-film semiconductors. The method yields a spatially resolved conductivity profile and allows the determination of Peltier coefficients. Results obtained on doped hydrogenated amorphous silicon films are presented

  6. A Hot-Wire Method Based Thermal Conductivity Measurement Apparatus for Teaching Purposes

    Science.gov (United States)

    Alvarado, S.; Marin, E.; Juarez, A. G.; Calderon, A.; Ivanov, R.

    2012-01-01

    The implementation of an automated system based on the hot-wire technique is described for the measurement of the thermal conductivity of liquids using equipment easily available in modern physics laboratories at high schools and universities (basically a precision current source and a voltage meter, a data acquisition card, a personal computer…

  7. What we can learn from measurements of air electric conductivity in 222Rn-rich atmosphere

    Science.gov (United States)

    Seran, E.; Godefroy, M.; Pili, E.; Michielsen, N.; Bondiguel, S.

    2017-02-01

    Electric conductivity of air is an important characteristic of the electric properties of an atmosphere. Testing instruments to measure electric conductivity ranging from 10-13 to 10-9 S m-1 in natural conditions found in the Earth atmosphere is not an easy task. One possibility is to use stratospheric balloon flights; another (and a simpler one) is to look for terrestrial environments with significant radioactive decay. In this paper we present measurements carried out with different types of conductivity sensors in two 222Rn-rich environments, i.e., in the Roselend underground tunnel (French Alps) and in the Institute of Radioprotection and Nuclear Safety BACCARA (BAnC de CAllibrage du RAdon) chamber. The concept of the conductivity sensor is based on the classical time relaxation method. New elements in our design include isolation of the sensor sensitive part (electrode) from the external electric field and sensor miniaturization. This greatly extends the application domain of the sensor and permits to measure air electric conductivity when the external electric field is high and varies from few tens of V m-1 to up to few tens of kV m-1. This is suitable to propose the instrument for a planetary mission. Two-fold objectives were attained as the outcome of these tests and their analysis. First was directly related to the performances of the conductivity sensors and the efficiency of the conductivity sensor design to shield the external electric field. Second objective aimed at understanding the decay mechanisms of 222Rn and its progeny in atmosphere and the impact of the enclosed space on the efficiency of gas ionization.

  8. Conduction properties of KcsA measured using brownian dynamics with flexible carbonyl groups in the selectivity filter.

    Science.gov (United States)

    Chung, Shin-Ho; Corry, Ben

    2007-07-01

    In the narrow segment of an ion conducting pathway, it is likely that a permeating ion influences the positions of the nearby atoms that carry partial or full electronic charges. Here we introduce a method of incorporating the motion of charged atoms lining the pore into Brownian dynamics simulations of ion conduction. The movements of the carbonyl groups in the selectivity filter of the KcsA channel are calculated explicitly, allowing their bond lengths, bond angles, and dihedral angels to change in response to the forces acting upon them. By systematically changing the coefficients of bond stretching and of angle bending, the carbon and oxygen atoms can be made to fluctuate from their fixed positions by varying mean distances. We show that incorporating carbonyl motion in this way does not alter the mechanism of ion conduction and only has a small influence on the computed current. The slope conductance of the channel increases by approximately 25% when the root mean-square fluctuations of the carbonyl groups are increased from 0.01 to 0.61 A. The energy profiles and the number of resident ions in the channel remain unchanged. The method we utilized here can be extended to allow the movement of glutamate or aspartate side chains lining the selectivity filters of other ionic channels.

  9. Sensitivity studies on the multi-sensor conductivity probe measurement technique for two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Worosz, Ted [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, PA 16802 (United States); Bernard, Matt [The United States Nuclear Regulatory Commission, 11545 Rockville Pike, Rockville, MD 20852 (United States); Kong, Ran; Toptan, Aysenur [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, PA 16802 (United States); Kim, Seungjin, E-mail: skim@psu.edu [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, PA 16802 (United States); Hoxie, Chris [The United States Nuclear Regulatory Commission, 11545 Rockville Pike, Rockville, MD 20852 (United States)

    2016-12-15

    Highlights: • Revised conductivity probe circuit to eliminate signal “ghosting” among sensors. • Higher sampling frequencies suggested for bubble number frequency and a{sub i} measurements. • Two-phase parameter sensitivity to measurement duration and bubble number investigated. • Sensors parallel to pipe wall recommended for symmetric bubble velocity measurements. • Sensor separation distance ratio (s/d) greater than four minimizes bubble velocity error. - Abstract: The objective of this study is to advance the local multi-sensor conductivity probe measurement technique through systematic investigation into several practical aspects of a conductivity probe measurement system. Firstly, signal “ghosting” among probe sensors is found to cause artificially high bubble velocity measurements and low interfacial area concentration (a{sub i}) measurements that depend on sampling frequency and sensor impedance. A revised electrical circuit is suggested to eliminate this artificial variability. Secondly, the sensitivity of the probe measurements to sampling frequency is investigated in 13 two-phase flow conditions with superficial liquid and gas velocities ranging from 1.00–5.00 m/s and 0.17–2.0 m/s, respectively. With increasing gas flow rate, higher sampling frequencies, greater than 100 kHz in some cases, are required to adequately capture the bubble number frequency and a{sub i} measurements. This trend is due to the increase in gas velocity and the transition to the slug flow regime. Thirdly, the sensitivity of the probe measurements to the measurement duration as well as the sample number is investigated for the same flow conditions. Measurements of both group-I (spherical/distorted) and group-II (cap/slug/churn-turbulent) bubbles are found to be relatively insensitive to both the measurement duration and the number of bubbles, as long as the measurements are made for a duration long enough to capture a collection of samples characteristic to a

  10. Very high channel conductivity in low-defect AlN/GaN high electron mobility transistor structures

    International Nuclear Information System (INIS)

    Dabiran, A. M.; Wowchak, A. M.; Osinsky, A.; Xie, J.; Hertog, B.; Cui, B.; Chow, P. P.; Look, D. C.

    2008-01-01

    Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (>1800 cm 2 /V s) and sheet charge density (>3x10 13 cm -2 ), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to ∼100 Ω/□ at room temperature. Fabricated 1.2 μm gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of ∼1.3 A/mm and a peak transconductance of ∼260 mS/mm. Here, an all MBE growth of optimized AlN/GaN HEMT structures plus the results of thin-film characterizations and device measurements are presented

  11. Measurement channel of neutron flow based on software; Canal de medicion de flujo neutronico basado en software

    Energy Technology Data Exchange (ETDEWEB)

    Rivero G, T.; Benitez R, J. S. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: trg@nuclear.inin.mx

    2008-07-01

    The measurement of the thermal power in nuclear reactors is based mainly on the measurement of the neutron flow. The presence of these in the reactor core is associated to neutrons released by the fission reaction of the uranium-235. Once moderate, these neutrons are precursors of new fissions. This process it is known like chain reaction. Thus, the power to which works a nuclear reactor, he is proportional to the number of produced fissions and as these depend on released neutrons, also the power is proportional to the number of present neutrons. The measurement of the thermal power in a reactor is realized with called instruments nuclear channels. To low power (level source), these channels measure the individual counts of detected neutrons, whereas to a medium and high power, they measure the electrical current or fluctuation of the same one that generate the fission neutrons in ionization chambers especially designed to detect neutrons. For the case of TRIGA reactors, the measurement channels of neutron flow use discreet digital electronic technology makes some decades already. Recently new technological tools have arisen that allow developing new versions of nuclear channels of simple form and compacts. The present work consists of the development of a nuclear channel for TRIGA reactors based on the use of the correlated signal of a fission chamber for ample interval. This new measurement channel uses a data acquisition card of high speed and the data processing by software that to the being installed in a computer is created a virtual instrument, with what spreads in real time, in graphic and understandable form for the operator, the power indication to which it operates the nuclear reactor. This system when being based on software, offers a major versatility to realize changes in the signal processing and power monitoring algorithms. The experimental tests of neutronic power measurement show a reliable performance through seven decades of power, with a

  12. Thermal conductivity measurements of PTFE and Al2O3 ceramic at sub-Kelvin temperatures

    Science.gov (United States)

    Drobizhev, Alexey; Reiten, Jared; Singh, Vivek; Kolomensky, Yury G.

    2017-07-01

    The design of low temperature bolometric detectors for rare event searches necessitates careful selection and characterization of structural materials based on their thermal properties. We measure the thermal conductivities of polytetrafluoroethylene (PTFE) and Al2O3 ceramic (alumina) in the temperature ranges of 0.17-0.43 K and 0.1-1.3 K, respectively. For the former, we observe a quadratic temperature dependence across the entire measured range. For the latter, we see a cubic dependence on temperature above 0.3 K, with a linear contribution below that temperature. This paper presents our measurement techniques, results, and theoretical discussions.

  13. Small and intermediate conductance Ca(2+)-activated K+ channels confer distinctive patterns of distribution in human tissues and differential cellular localisation in the colon and corpus cavernosum.

    Science.gov (United States)

    Chen, Mao Xiang; Gorman, Shelby A; Benson, Bill; Singh, Kuljit; Hieble, J Paul; Michel, Martin C; Tate, Simon N; Trezise, Derek J

    2004-06-01

    The SK/IK family of small and intermediate conductance calcium-activated potassium channels contains four members, SK1, SK2, SK3 and IK1, and is important for the regulation of a variety of neuronal and non-neuronal functions. In this study we have analysed the distribution of these channels in human tissues and their cellular localisation in samples of colon and corpus cavernosum. SK1 mRNA was detected almost exclusively in neuronal tissues. SK2 mRNA distribution was restricted but more widespread than SK1, and was detected in adrenal gland, brain, prostate, bladder, liver and heart. SK3 mRNA was detected in almost every tissue examined. It was highly expressed in brain and in smooth muscle-rich tissues including the clitoris and the corpus cavernosum, and expression in the corpus cavernosum was upregulated up to 5-fold in patients undergoing sex-change operations. IK1 mRNA was present in surface-rich, secretory and inflammatory cell-rich tissues, highest in the trachea, prostate, placenta and salivary glands. In detailed immunohistochemical studies of the colon and the corpus cavernosum, SK1-like immunoreactivity was observed in the enteric neurons. SK3-like immunoreactivity was observed strongly in smooth muscle and vascular endothelium. IK1-like immunoreactivity was mainly observed in inflammatory cells and enteric neurons of the colon, but absent in corpus cavernosum. These distinctive patterns of distribution suggest that these channels are likely to have different biological functions and could be specifically targeted for a number of human diseases, such as irritable bowel syndrome, hypertension and erectile dysfunction.

  14. A new technique for precise measurement of thermal conductivity of metals at normal and high temperatures

    International Nuclear Information System (INIS)

    Binkele, L.

    1990-09-01

    Theoretical and experimental investigations on a new measuring technique are described; a technique similar to the well known Kohlrausch measuring technique, which is characterized by direct electrical sample heating. Subject of the investigations is a cylindrical metallic sample, 5 mm thick and 200 mm in length, which is positioned vertically between water-cooled clamps in a vacuum container. The sample can be heated using two simultaneously operating current sources, a 50 Hz-source for axial flow (main heating) as well as a 200 kHz-induction source for generating eddy currents in two short regions above and below the sample centre (additional heating). By using two heating sources different symmetrical temperature profiles in a central eddy-current-free area of about ± 10mm can be produced for any given central sample temperature. The last chapter contains thermal conductivity and electrical resistivity measuring curves for Pt, W, Fe, Ni, Ag, Al, Mg, Ir, Ru, Re, Ho and Y in the temperature range 273 to 1500 K representative of all the metals and alloys investigated. In cases where comparisons with published precise conductivity data, established by other measuring techniques in restricted temperature ranges, were posible, the new measuring method is greatly supported (in the case of Pt, W, Ni, Ag, Al). For the Metals Ir, Ru, Re, Ho and Y high temperature thermal conductivity data are given for the first time. (orig./MM) [de

  15. Concept for a MEMS-type vacuum sensor based on electrical conductivity measurements

    Directory of Open Access Journals (Sweden)

    F. J. Giebel

    2017-11-01

    Full Text Available The concept of the micro-structured vacuum sensor presented in this article is the measurement of the electrical conductivity of thinned gases in order to develop a small, economical and quite a simple type of vacuum sensor. There are already some approaches for small vacuum sensors. Most of them are based on conservative measurement principles similar to those used in macroscopic vacuum gauges. Ionization gauges use additional sources of energy, like hot cathodes, ultraviolet radiation or high voltage for example, for ionizing gas molecules and thereby increasing the number of charge carriers for measuring low pressures. In contrast, the concept discussed here cannot be found in macroscopic sensor systems because it depends on the microscopic dimension of a gas volume defined by two electrodes. Here we present the concept and the production of a micro-structured vacuum sensor chip, followed by the electrical characterization. Reference measurements with electrodes at a distance of about 1 mm showed currents in the size of picoampere and a conductivity depending on ambient pressure. In comparison with these preliminary measurements, fundamental differences regarding pressure dependence of the conductivity are monitored in the electrical characterization of the micro-structured sensor chip. Finally the future perspectives of this sensor concept are discussed.

  16. Simultaneous reconstruction of permittivity and conductivity using multi-frequency admittance measurement in electrical capacitance tomography

    International Nuclear Information System (INIS)

    Zhang, Maomao; Soleimani, Manuchehr

    2016-01-01

    Electrical capacitance tomography (ECT) is an imaging method mainly capable of reconstructing dielectric permittivity. Generally, the reactance part of complex admittance is measured in a selected frequency. This paper presents for the first time an in depth and systematic analysis of complex admittance data for simultaneous reconstruction of both electrical conductivity and dielectric permittivity. A complex-valued forward model, Jacobian matrix and inverse solution are developed in the time harmonic excitation mode to allow for multi-frequency measurements. Realistic noise models are used to evaluate the performance of complex admittance ECT in a range of excitation frequencies. This paper demonstrates far greater potential for ECT as a versatile imaging tool through novel analysis of complex admittance imaging using a dual conductivity permittivity inversion method. The paper demonstrates that various classes of contactless capacitance based measurement devices can be analysed through complex multi-frequency ECT. (paper)

  17. The design of high-temperature thermal conductivity measurements apparatus for thin sample size

    Directory of Open Access Journals (Sweden)

    Hadi Syamsul

    2017-01-01

    Full Text Available This study presents the designing, constructing and validating processes of thermal conductivity apparatus using steady-state heat-transfer techniques with the capability of testing a material at high temperatures. This design is an improvement from ASTM D5470 standard where meter-bars with the equal cross-sectional area were used to extrapolate surface temperature and measure heat transfer across a sample. There were two meter-bars in apparatus where each was placed three thermocouples. This Apparatus using a heater with a power of 1,000 watts, and cooling water to stable condition. The pressure applied was 3.4 MPa at the cross-sectional area of 113.09 mm2 meter-bar and thermal grease to minimized interfacial thermal contact resistance. To determine the performance, the validating process proceeded by comparing the results with thermal conductivity obtained by THB 500 made by LINSEIS. The tests showed the thermal conductivity of the stainless steel and bronze are 15.28 Wm-1K-1 and 38.01 Wm-1K-1 with a difference of test apparatus THB 500 are −2.55% and 2.49%. Furthermore, this apparatus has the capability to measure the thermal conductivity of the material to a temperature of 400°C where the results for the thermal conductivity of stainless steel is 19.21 Wm-1K-1 and the difference was 7.93%.

  18. IN SITU density measurements oozy bottom of the access channel to the port of Santos, Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Minardi, P.S.P.

    1988-09-01

    The density of the bottom sediment of the access channel to the port of Santos, Sao Paulo, Brazil was measured. The in situ measurements aimed at verifying the use for navigation purposes of the layers with densities equal to or smaller than 1200 kg/m 3 . (F.E.). 3 refs, 55 figs, 3 tabs

  19. A MIMO-OFDM Testbed, Channel Measurements, and System Considerations for Outdoor-Indoor WiMAX

    Directory of Open Access Journals (Sweden)

    Torres

    2010-01-01

    Full Text Available The design, implementation, and test of a real-time flexible (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing MIMO-OFDM IEEE 802.16 prototype are presented. For the design, a channel measurement campaign on the 3.5 GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter CDIT capacity is close to (Channel State Information at the Transmitter CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements.

  20. A MIMO-OFDM Testbed, Channel Measurements, and System Considerations for Outdoor-Indoor WiMAX

    Directory of Open Access Journals (Sweden)

    Víctor P. Gil Jiménez

    2010-01-01

    Full Text Available The design, implementation, and test of a real-time flexible 2×2 (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing MIMO-OFDM IEEE 802.16 prototype are presented. For the design, a channel measurement campaign on the 3.5 GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter CDIT capacity is close to (Channel State Information at the Transmitter CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements.

  1. Time- and Space-Domain Measurements of the Thermal Conductivity in Diamond Anvil Cells

    Science.gov (United States)

    Goncharov, A. F.

    2011-12-01

    I will give an overview of recent developments of experimental techniques to measure the thermal conductivity in diamond anvil cell (DAC) under conditions of high pressure and high temperature (P-T) which are relevant for the planetary interiors. To measure the lattice contributions to the thermal conductivity, we developed a transient heating technique (THT) in the diamond anvil cell (DAC) [1]. This technique utilizes a periodic front surface temperature variation (measured by the spectroradiometry) of a metallic absorber surrounded by the material of interest and exposed to a pulsed laser radiation (10 nanoseconds pulses). We extract the thermal diffusivity of minerals by fitting the experimental results to the model finite element (FE) calculations. We have recently modified this technique for microseconds laser pulses as this allows avoiding nonequilibrium heat transfer processes. We have measured the thermal conductivity of Ar up to 50 GPa and 2500 K; the results are in agreement with the theoretical calculations [2] in the limit of high temperatures. In collaboration with a group from the University of Illinois we have utilized a time-domain thermoreflectance (TDTR)- ultrafast (femtosecond) laser pump-probe technique for measurement of the lattice thermal conductivity at high P-T conditions. We have measured the thermal conductivity of MgO up to 60 GPa and 300 K and up to 45 GPa at 600 K. The detailed results of this study will be presented in a separate paper at this Meeting. Finally, we have combined static and pulsed laser techniques to determine the thermal conductivity of Fe and its temperature dependence at high pressures up to 70 GPa and 2000 K [3]. A thin plate of Fe was positioned in an Ar medium, laser heated from one side and the temperature is being measured from both sides of the sample radiometrically. The thermal conductivity has been determined by fitting the results of FE calculations to the experimental results. These examples demonstrate

  2. The analysis of Rutherford scattering-channelling measurements of disorder production and annealing in ion irradiated semiconductors

    International Nuclear Information System (INIS)

    Carter, G.; Elliman, R.G.

    1983-01-01

    Rutherford scattering and channelling of light probe ions (e.g. He + ) has been extensively used for studies of disorder production in ion implanted semiconductors. Various authors have analysed models of amorphousness accumulation and Carter and Webb have indicated the general difficulties in assessing disorder production models from RBS/channelling studies if the production modes are complex and the manner in which the technique responds to different defect structures is unspecified. For less complex disorder production modes and by making reasonable assumptions about the technique response however, some insight into the form of backscattering yield - ion implant fluence functions can be obtained as is discussed in the present communication. It thus becomes possible to infer the importance of different disorder generation processes from RBS/channelling - ion influence studies. It will also be shown how simple annealing processes modify disorder accumulation and thus again how the operation of such processes may be inferred from RBS/channelling - ion fluence measurements. (author)

  3. Study on characteristics of a double-conductible channel organic thin-film transistor with an ultra-thin hole-blocking layer

    International Nuclear Information System (INIS)

    Guang-Cai, Yuan; Zheng, Xu; Su-Ling, Zhao; Fu-Jun, Zhang; Xue-Yan, Tian; Xu-Rong, Xu; Na, Xu

    2009-01-01

    The properties of top-contact organic thin-film transistors (TC-OTFTs) using ultra-thin 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline (BCP) as a hole-blocking interlayer have been improved significantly and a BCP interlayer was inserted into the middle of the pentacene active layer. This paper obtains a fire-new transport mode of an OTFT device with double-conductible channels. The accumulation and transfer of the hole carriers are limited by the BCP interlayer in the vertical region of the channel. A huge amount of carriers is located not only at the interface between pentacene and the gate insulator, but also at the two interfaces of pentacene/BCP interlayer and pentacene/gate insulator, respectively. The results suggest that the BCP interlayer may be useful to adjust the hole accumulation and transfer, and can increase the hole mobility and output current of OTFTs. The TC-OTFTs with a BCP interlayer at V DS = −20 V showed excellent hole mobility μFE and threshold voltage V TH of 0.58 cm 2 /(V·s) and −4.6 V, respectively

  4. A hot-wire method based thermal conductivity measurement apparatus for teaching purposes

    International Nuclear Information System (INIS)

    Alvarado, S; Marín, E; Juárez, A G; Calderón, A; Ivanov, R

    2012-01-01

    The implementation of an automated system based on the hot-wire technique is described for the measurement of the thermal conductivity of liquids using equipment easily available in modern physics laboratories at high schools and universities (basically a precision current source and a voltage meter, a data acquisition card, a personal computer and a high purity platinum wire). The wire, which is immersed in the investigated sample, is heated by passing a constant electrical current through it, and its temperature evolution, ΔT, is measured as a function of time, t, for several values of the current. A straightforward methodology is then used for data processing in order to obtain the liquid thermal conductivity. The start point is the well known linear relationship between ΔT and ln(t) predicted for long heating times by a model based on a solution of the heat conduction equation for an infinite lineal heat source embedded in an infinite medium into which heat is conducted without convective and radiative heat losses. A criterion is used to verify that the selected linear region is the one that matches the conditions imposed by the theoretical model. As a consequence the method involves least-squares fits in linear, semi-logarithmic (semi-log) and log-log graphs, so that it becomes attractive not only to teach about heat transfer and thermal properties measurement techniques, but also as a good exercise for students of undergraduate courses of physics and engineering learning about these kinds of mathematical functional relationships between variables. The functionality of the experiment was demonstrated by measuring the thermal conductivity in samples of liquids with well known thermal properties. (paper)

  5. Contactless graphene conductance measurements: the effect of device fabrication on terahertz time-domain spectroscopy

    DEFF Research Database (Denmark)

    Mackenzie, David; Buron, Jonas Christian Due; Bøggild, Peter

    2016-01-01

    We perform contactless full-wafer maps of the electrical conductance of a 4-inch wafer of single-layer CVD graphene using terahertz time-domain spectroscopy both before and after deposition of metal contacts and fabrication of devices via laser ablation. We find that there is no significant change...... in the measured conductance of graphene before and after device fabrication. We also show that precise terahertz time-domain spectroscopy can be performed when the beam spot is at sufficient distance (>1.2 mm) from metal contacts....

  6. Identification of Scattering Mechanisms from Measured Impulse Response Signatures of Several Conducting Objects.

    Science.gov (United States)

    1984-02-01

    conducting sphere 35 compared to inverse transform of exact solution. 4-5. Measured impulse response of a conducting 2:1 right 37 circular cylinder with...frequency domain. This is equivalent to multiplication in the time domain by the inverse transform of w(n), which is shown in Figure 3-1 for N=15. The...equivalent pulse width from 0.066 T for the rectangular window to 0.10 T for the Hanning window. The inverse transform of the Hanning window is shown

  7. Measurement of in-situ hydraulic conductivity in the Cretaceous Pierre Shale

    International Nuclear Information System (INIS)

    Neuzil, C.E.; Bredehoeft, J.D.

    1981-01-01

    A recent study of the hydrology of the Cretaceous Pierre Shale utilized three techniques for measuring the hydraulic conductivity of tight materials. Regional hydraulic conductivity was obtained from a hydrodynamic model analysis of the aquifer-aquitard system which includes the Pierre Shale. Laboratory values were obtained from consolidation tests on core samples. In-situ values of hydraulic conductivity were obtained by using a borehole slug test designed specifically for tight formations. The test is conducted by isolating a portion of the borehole with one or two packers, abruptly pressurizing the shut-in portion, and recording the pressure decay with time. The test utilizes the analytical solution for pressure decay as water flows into the surrounding formation. Consistent results were obtained using the test on three successively smaller portions of a borehole in the Pierre Shale. The in-situ tests and laboratory tests yielded comparable values; the regional hydraulic conductivity was two to three orders of magnitude larger. This suggests that the lower values represent intergranular hydraulic conductivity of the intact shale and the regional values represent secondary permeability due to fractures. Calculations based on fracture flow theory demonstrate that small fractures could account for the observed differences

  8. Electrical conductivity measurement and thermogravimetric study of chromium-doped uranium dioxide

    International Nuclear Information System (INIS)

    Matsui, Tsuneo; Naito, Keiji

    1986-01-01

    The electrical conductivity and nonstoichiometric composition of (Usub(1-y)Crsub(y))Osub(2+x) (y=0.001 and 0.05) were measured in the range 1173 -17 2 ) -2 Pa by the four inserted wires method and thermogravimetry, respectively. The electrical conductivities of (Usub(1-y)Crsub(y))Osub(2+x) (y=0.01 and 0.05) were about one-order lower than that of UOsub(2+x), probably due to the presence of the chromium ion as an electron donor. The activation energies of (Usub(0.99)Crsub(0.01))Osub(2+x) and (Usub(0.95)Crsub(0.05))Osub(2+x) for the extrinsic conduction in the low oxygen partial pressure region were calculated to be 24.7+-1.3 and 25.9+-1.0 kJ.mol -1 , respectively from the Arrhenius plots of the electrical conductivities. These small values of the activation energy of (Usub(1-y)Crsub(y))Osub(2+x) may suggest the presence of the hopping mechanism for hole conduction, similarly to the case of UOsub(2+x). From the oxygen partial pressure dependences of both the electrical conductivity and the deviation x in (Usub(1-y)Crsub(y))Osub(2+x), the defect structure was discussed with the complex defect model consisting of oxygen vacancies and two kinds of interstitial oxygens. (orig.)

  9. Measurement of the Thermal Conductivity of Nano-fluid for the advanced heat exchanger

    International Nuclear Information System (INIS)

    Yoo, Shin; Lee, Jae Young

    2006-01-01

    The enhancement of heat transfer has been widely investigated to provide an effective way to cool down the modern electronic devices. Among the methods, Choi discovered a large amount of increase of thermal conductivity when nano sized particles were suspended in the fluid. It was first introduced by Masuda as a potential heat transfer enhancement media and since then, many researchers have investigated the nanofluids phenomena. Many researchers reported in substantially increasing the thermal conductivity of fluids by adding small amounts of suspended metallic oxide nanoparticles of Cu, CuO, Al 2 O 3 and carbon nano-tube. Masuda reported that the use Al 2 O 3 particles of 13 nm at 4.3% volume fraction increased the thermal conductivity of water by 30%. For carbon nano-tube nanofluids shows even greater enhancement. Xie et al. measured the thermal conductivity of carbon nanotube suspended in organic liquid and water with the enhancement of 10-20%. Recent studies have shown that inserting just 1% concentration of nano-particles sometimes increases about maximum 40% of thermal conductivity. However, there is still few experiments done for TiO 2 nanoparticles. Murshed found that the enhancement of thermal conductivity shows about 30% with 15nm in diameter with maximum 5% volume fraction and about 40% enhancement is observed using 15nmD x 40nm rod-shape nanoparticles of TiO 2 . The present experimental shows that a 20% maximum of enhancement in thermal conductivity using TiO 2 of 10nm for 3% volume fraction. Theses results are compared with previous research with theoretical models. As the first step of the heat transfer of nano fluid, the theories related to the nanofluids investigations have been discussed to understand not only the mechanism of thermal conductivity measurement, but also to understand the nanofluid behavior. Colloidal stability is the key to the nanofluid considered to prevent the agglomeration. Through the results, we will discuss the importance of

  10. Advances in estimation technology of thermal conductivity of irradiated fuels (1). Application of a thermal microscope to measure the thermal conductivity of the second phases in irradiated pellets

    International Nuclear Information System (INIS)

    Uno, Masayoshi; Murakami, Yukihiro

    2011-01-01

    CeO 2 sample as a surrogate for fuel and BaCeO 3 and BaMoO 4 samples as surrogates for the second phases, which have a lower thermal conductivity than the fuel matrix, were made. The thermal conductivity of these samples was measured by a thermal microscope. In this method, the thermal conductivity of a small region (e.g. 20 μm x 20 μm) of the sample can be measured. The valid thermal conductivity values for all the samples were obtained and the conditions of sample surface preparation and the thermal microscope measurement were found out. The thermal conductivity of a CeO 2 composite pellet which had the BaCeO 3 or BaMoO 4 second phase layer was also estimated. (author)

  11. Positive phase error from parallel conductance in tetrapolar bio-impedance measurements and its compensation

    Directory of Open Access Journals (Sweden)

    Ivan M Roitt

    2010-01-01

    Full Text Available Bioimpedance measurements are of great use and can provide considerable insight into biological processes.  However, there are a number of possible sources of measurement error that must be considered.  The most dominant source of error is found in bipolar measurements where electrode polarisation effects are superimposed on the true impedance of the sample.  Even with the tetrapolar approach that is commonly used to circumvent this issue, other errors can persist. Here we characterise the positive phase and rise in impedance magnitude with frequency that can result from the presence of any parallel conductive pathways in the measurement set-up.  It is shown that fitting experimental data to an equivalent electrical circuit model allows for accurate determination of the true sample impedance as validated through finite element modelling (FEM of the measurement chamber.  Finally, the model is used to extract dispersion information from cell cultures to characterise their growth.

  12. Low energy RBS-channeling measurement system with the use of a time-of-flight scattered ion detector

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Masataka; Kobayashi, Naoto; Hayashi, Nobuyuki [Electrotechnical Lab., Tsukuba, Ibaraki (Japan)

    1996-07-01

    We have developed a low energy Rutherford backscattering spectrometry-ion channeling measurement system for the analysis of thin films and solid surfaces with the use of several tens keV hydrogen ions and a time-of-flight particle energy spectrometer. For the detection of the scattered ions new TOF spectrometer has been developed, which consists of two micro-channel-plate detectors. The pulsing of the primary ion beam is not necessary for this type of TOF measurement, and it is possible to observe continues scattered ion beams. The dimension of whole system is very compact compared to the conventional RBS-channeling measurement system with the use of MeV He ions. The energy resolution, {delta} E/E, for 25 keV H{sup +} was 4.1%, which corresponds to the depth resolution of 4.8 nm for silicon. The depth resolution of our system is better than that of conventional RBS system with MeV helium ions and solid state detectors. We have demonstrated the ion channeling measurement by this system with 25 keV hydrogen ions. The system can be available well to the analysis of thin films and solid surfaces with the use of the ion channeling effect. The observation of the reaction between Fe and hydrogen terminated silicon surface was also demonstrated. (J.P.N.)

  13. Neutron flux measurement in the central channel (XC-1) of TRIGA 14 MW LEU core

    International Nuclear Information System (INIS)

    BARBOS, D.; BUSUIOC, P.; ROTH, Cs.; PAUNOIU, C.

    2008-01-01

    The TRIGA 14 MW reactor, operated by Institute for Nuclear Research Pitesti, Romania, is a pool type reactor, and has a rectangular shape which holds fuel bundles and is surrounded with beryllium reflectors. Each fuel bundle is composed of 25 nuclear fuel rods. The TRIGA 14 MW reactor was commissioned 28 years ago with HEU fuel rods. The conversion was gradually achieved, starting in February 1992 and completed in March 2006. The full conversion of the 14 MW TRIGA Research Reactor was completed in May 2006 and each step of the conversion was achieved by removal of HEU fuel, replaced by LEU fuel, accompanied by a large set of theoretical evaluation and physical measurements intended to confirm the performances of gradual conversion. After the core full conversion, a program of measurements and comparisons with previous results of core physics and measurements is underway, allowing data acquisition for normal operation, demonstration of safety and economics of the converted core. Neutron flux spectrum measurements in the XC in the XC-1 water 1 water-filled channel were performed using multi multi-foil activation techniques. The neutron spectra and flux are obtained by unfolding from measured reaction rates using SAND II computer code. The integral neutron flux value for LEU core is greater of 13% than for the standard HEU core. Also thermal neutron flux value for converted LEU core is smaller by 0.38% than for the standard HEU core. These differences appear because the foil activation detectors have been irradiated using a pneumatic rabbit having a diameter of 32 mm, whereas foil irradiations in standard HEU core has been performed with a pneumatic rabbit having a diameter of 14 mm, and therefore the neutron spectra in LEU core is less thermalized and the weight of fast neutron is greater

  14. A Multi-Functional Microelectrode Array Featuring 59760 Electrodes, 2048 Electrophysiology Channels, Stimulation, Impedance Measurement and Neurotransmitter Detection Channels.

    Science.gov (United States)

    Dragas, Jelena; Viswam, Vijay; Shadmani, Amir; Chen, Yihui; Bounik, Raziyeh; Stettler, Alexander; Radivojevic, Milos; Geissler, Sydney; Obien, Marie; Müller, Jan; Hierlemann, Andreas

    2017-06-01

    Biological cells are characterized by highly complex phenomena and processes that are, to a great extent, interdependent. To gain detailed insights, devices designed to study cellular phenomena need to enable tracking and manipulation of multiple cell parameters in parallel; they have to provide high signal quality and high spatiotemporal resolution. To this end, we have developed a CMOS-based microelectrode array system that integrates six measurement and stimulation functions, the largest number to date. Moreover, the system features the largest active electrode array area to date (4.48×2.43 mm 2 ) to accommodate 59,760 electrodes, while its power consumption, noise characteristics, and spatial resolution (13.5 μm electrode pitch) are comparable to the best state-of-the-art devices. The system includes: 2,048 action-potential (AP, bandwidth: 300 Hz to 10 kHz) recording units, 32 local-field-potential (LFP, bandwidth: 1 Hz to 300 Hz) recording units, 32 current recording units, 32 impedance measurement units, and 28 neurotransmitter detection units, in addition to the 16 dual-mode voltage-only or current/voltage-controlled stimulation units. The electrode array architecture is based on a switch matrix, which allows for connecting any measurement/stimulation unit to any electrode in the array and for performing different measurement/stimulation functions in parallel.

  15. Characteristics of four-channel Cherenkov-type detector for measurements of runaway electrons in the ISTTOK tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Plyusnin, V. V.; Duarte, P.; Fernandes, H.; Silva, C. [Instituto de Plasmas e FuSao Nuclear - Laboratorio Associado, Association Euratom/IST, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Jakubowski, L.; Zebrowski, J.; Malinowski, K.; Rabinski, M.; Sadowski, M. J. [The Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland)

    2010-10-15

    A diagnostics capable of characterizing the runaway and superthermal electrons has been developing on the ISTTOK tokamak. In previous paper, a use of single-channel Cherenkov-type detector with titanium filter for runaway electron studies in ISTTOK was reported. To measure fast electron populations with different energies, a prototype of a four-channel detector with molybdenum filters was designed. Test-stand studies of filters with different thicknesses (1, 3, 7, 10, 20, 50, and 100 {mu}m) have shown that they should allow the detection of electrons with energies higher than 69, 75, 87, 95, 120, 181, and 260 keV, respectively. First results of measurements with the four-channel detector revealed the possibility to measure reliably different fast electrons populations simultaneously.

  16. A New system for Measuring Electrical Conductivity of Water as a Function of Admittance

    Directory of Open Access Journals (Sweden)

    Haval Yacoob

    2011-12-01

    Full Text Available This paper presents a new system for measuring water conductivity as a function of electrophysical property (admittance. The system is cheap and its manufacturing is easy. In addition, it dose not require any sort of electrolysis and calibration. The system consists of four electrodes made of silver (Ag 92.5 g to Cu 7.5 g fixed in a plastic tube filled by water which allows the use of two and four electrode setups. The admittance (reciprocal of impedance is measured for different water sources (distilled, rainfall, mineral, river and tap water using different frequencies between 50 Hz and 100 kHz. These measurements were taken twice, once with four electrodes and another with two electrodes of two modes (inner and outer electrodes. The results have shown good correlation between the measured admittance and the conductivity of all the water sources and the best correlation was found at low frequencies between 50 Hz and 20 kHz. The highest efficiency can be achieved by performing the four electrodes system which allows circumventing the effect of the electrode impedance. This result makes the system efficient compared to traditional conductivity meters which usually require high frequencies for good operation. doi:10.5617/jeb.203 J Electr Bioimp, vol. 2, pp. 86-92, 2011

  17. The measurement of the vertical component of hydraulic conductivity in single-cased and uncased boreholes

    International Nuclear Information System (INIS)

    Black, J.H.; Noy, D.J.; Brightman, M.A.

    1987-01-01

    The project aimed to assess the different existing methods of measuring vertical hydraulic conductivity in single boreholes by carrying out some actual field testing. A review of existing techniques for both field practice and analysis of the results is reported. After consideration of the various techniques a combination method of testing is proposed. A set of equipment to carry out this combination of tests was designed and built. The uncased testing revealed that it was possible to derive a value for vertical hydraulic conductivity. The doublet method, however, was not particularly successful and numerical simulation was cumbersome. The type-curve approach of appraising whether or not analysis concepts were appropriate proved the most robust method. It is clear that reconnaissance measurements of environmental pressure are very useful in defining where detailed testing should take place. The second phase of testing through perforations proved very difficult. There were many problems associated with location both of the wireline testing system within the borehole and especially of the previous measurements. However, analysis of the results in terms of skin indicated that the perforations produced a negative skin. The measurement of vertical hydraulic conductivity cannot at the moment be regarded as routine

  18. A small-plane heat source method for measuring the thermal conductivities of anisotropic materials

    Science.gov (United States)

    Cheng, Liang; Yue, Kai; Wang, Jun; Zhang, Xinxin

    2017-07-01

    A new small-plane heat source method was proposed in this study to simultaneously measure the in-plane and cross-plane thermal conductivities of anisotropic insulating materials. In this method the size of the heat source element is smaller than the sample size and the boundary condition is thermal insulation due to no heat flux at the edge of the sample during the experiment. A three-dimensional model in a rectangular coordinate system was established to exactly describe the heat transfer process of the measurement system. Using the Laplace transform, variable separation, and Laplace inverse transform methods, the analytical solution of the temperature rise of the sample was derived. The temperature rises calculated by the analytical solution agree well with the results of numerical calculation. The result of the sensitivity analysis shows that the sensitivity coefficients of the estimated thermal conductivities are high and uncorrelated to each other. At room temperature and in a high-temperature environment, experimental measurements of anisotropic silica aerogel were carried out using the traditional one-dimensional plane heat source method and the proposed method, respectively. The results demonstrate that the measurement method developed in this study is effective and feasible for simultaneously obtaining the in-plane and cross-plane thermal conductivities of the anisotropic materials.

  19. An improved electrical-conductance sensor for void-fraction measurement in a horizontal pipe

    International Nuclear Information System (INIS)

    Ko, Min Seok; Jemg, Dong Wook; Kim, Sin; Lee, Bo An; Won, Woo Youn; Lee, Yeon Gun

    2015-01-01

    The electrical-impedance method has been widely used for void-fraction measurement in two-phase flow due to its many favorable features. In the impedance method, the response characteristics of the electrical signal heavily depend upon flow pattern, as well as phasic volume. Thus, information on the flow pattern should be given for reliable void-fraction measurement. This study proposes an improved electrical-conductance sensor composed of a three-electrode set of adjacent and opposite electrodes. In the proposed sensor, conductance readings are directly converted into the flow pattern through a specified criterion and are consecutively used to estimate the corresponding void fraction. Since the flow pattern and the void fraction are evaluated by reading conductance measurements, complexity of data processing can be significantly reduced and real-time information provided. Before actual applications, several numerical calculations are performed to optimize electrode and insulator sizes, and optimal design is verified by static experiments. Finally, the proposed sensor is applied for air-water two-phase flow in a horizontal loop with a 40-mm inner diameter and a 5-m length, and its measurement results are compared with those of a wire-mesh sensor

  20. Photoacoustic infrared spectroscopy for conducting gas tracer tests and measuring water saturations in landfills

    International Nuclear Information System (INIS)

    Jung, Yoojin; Han, Byunghyun; Mostafid, M. Erfan; Chiu, Pei; Yazdani, Ramin; Imhoff, Paul T.

    2012-01-01

    Highlights: ► Photoacoustic infrared spectroscopy tested for measuring tracer gas in landfills. ► Measurement errors for tracer gases were 1–3% in landfill gas. ► Background signals from landfill gas result in elevated limits of detection. ► Technique is much less expensive and easier to use than GC. - Abstract: Gas tracer tests can be used to determine gas flow patterns within landfills, quantify volatile contaminant residence time, and measure water within refuse. While gas chromatography (GC) has been traditionally used to analyze gas tracers in refuse, photoacoustic spectroscopy (PAS) might allow real-time measurements with reduced personnel costs and greater mobility and ease of use. Laboratory and field experiments were conducted to evaluate the efficacy of PAS for conducting gas tracer tests in landfills. Two tracer gases, difluoromethane (DFM) and sulfur hexafluoride (SF 6 ), were measured with a commercial PAS instrument. Relative measurement errors were invariant with tracer concentration but influenced by background gas: errors were 1–3% in landfill gas but 4–5% in air. Two partitioning gas tracer tests were conducted in an aerobic landfill, and limits of detection (LODs) were 3–4 times larger for DFM with PAS versus GC due to temporal changes in background signals. While higher LODs can be compensated by injecting larger tracer mass, changes in background signals increased the uncertainty in measured water saturations by up to 25% over comparable GC methods. PAS has distinct advantages over GC with respect to personnel costs and ease of use, although for field applications GC analyses of select samples are recommended to quantify instrument interferences.

  1. CHANNELING: SEARCH OF THE METAANTHROPOLOGIC MEAS-UREMENTS OF MIND BEING IN THE UNIVERSE (based on the World Wide Web

    Directory of Open Access Journals (Sweden)

    Anatoly T. Tshedrin

    2014-06-01

    Full Text Available The relevance of the study. In the context of religious and philosophical movements of the «New Age» gained channeling phenomenon – «laying channel», «transmission channel» information from the consciousness that is not in human form, to the individual and humanity as a whole. In the socio-cultural environment of the postmodern channeling reflects the problem of finding extraterrestrial intelligence (ETI; «ETC-problem»; SETІ problem and to establish contacts with them, this problem has a different projection, important philosophical and anthropological measurements in culture. Investigation of mechanisms of constructing virtual superhuman personalities in the world web is not only of interest for further analysis of the problem of extraterrestrial intelligence (ETI, but also to extend subject field of anthropology of the Internet as an important area of philosophical and anthropological studies. The purpose of the study. Analysis of the phenomenon of channeling as a projection of the fundamental problems of life ETI, its representation on the World Wide Web, the impact on the archaism of postmodern culture posing problems meta an-thropological dimensions of existence in the universe of reason and contact with him in the doctrinal grounds channeling. Analysis of research on the problem and its empirical base. Clustered nature of the problem of ETI and channeling its element involves the widespread use of radio astronomy paradigm works carriers solve CETI; work in anthropology Internet; works of researchers of the phenomenon of «New Age». Empirical basis of the study are network resources, as well as texts–representatives created and introduced into circulation by the channelers, their predecessors. Research Methodology. Channeling as an object of research, its network of representation – as a matter of methods involve the use of analytical hermeneutics and archaeographic commenting text fractal logic cluster analysis. The main

  2. Low-temperature conducting channel switching in hybrid Fe{sub 3}O{sub 4}/SiO{sub 2}/n-Si structures

    Energy Technology Data Exchange (ETDEWEB)

    Vikulov, V.A., E-mail: vikulov@iacp.dvo.ru [Institute of Automation and Control Processes, FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Dimitriev, A.A.; Balashev, V.V.; Pisarenko, T.A.; Korobtsov, V.V. [Institute of Automation and Control Processes, FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation)

    2016-09-15

    Highlights: • Conducting channel switching between the polycrystalline Fe{sub 3}O{sub 4} film and the n-Si substrate takes place in the Fe{sub 3}O{sub 4}/SiO{sub 2}/n-Si structure at temperature below 125 K. • This effect occurs via the field-assisted tunneling through the composite insulating layer that consists of the highly resistive Fe{sub 3}O{sub 4} and the tunnel SiO{sub 2}. • The switching is attended by a change in the shape of the current-voltage characteristics from the linear at 300 K to the S-type at 80 K. - Abstract: The carrier transport properties of the polycrystalline magnetite (Fe{sub 3}O{sub 4}) films grown on an n-type Si substrate with 5 nm-thick SiO{sub 2} have been investigated between 80 and 300 K in current-in-plane geometry. It was established that at temperature decrease to about 120 K, the resistivity of thin Fe{sub 3}O{sub 4} films increases up to a peak value and then abruptly drops. This process is attended by a change in the shape of the current-voltage characteristics from the linear at 300 K to the S-type at 80 K. The observed peculiarities are explained by conducting channel switching from the Fe{sub 3}O{sub 4} film to the Si substrate via the field-assisted tunneling of carriers through the composite insulating layer consisting of highly resistive Fe{sub 3}O{sub 4} and tunnel SiO{sub 2}.

  3. Cracked pellet gap conductance model: comparison of FRAP-S calculations with measured fuel centerline temperatures

    International Nuclear Information System (INIS)

    MacDonald, P.E.; Broughton, J.M.

    1975-03-01

    Fuel pellets crack extensively upon irradiation due both to thermal stresses induced by power changes and at high burnup, to accumulation of gaseous fission products at grain boundaries. Therefore, the distance between the fuel and cladding will be circumferentially nonuniform; varying between that calculated for intact operating fuel pellets and essentially zero (fuel segments in contact with the cladding wall). A model for calculation of temperatures in cracked pellets is proposed wherein the effective fuel to cladding gap conductance is calculated by taking a zero pressure contact conductance in series with an annular gap conductance. Comparisons of predicted and measured fuel centerline temperatures at beginning of life and at extended burnup are presented in support of the model. 13 references

  4. In situ measurement of the thermal conductivity in propylite rock mass

    International Nuclear Information System (INIS)

    Shimooka, Kenji; Araki, Kunio; Suda, Shintaro.

    1982-11-01

    The safety evaluation for the geological disposal of the high level waste becomes an urgent problem to establish the backend of nuclear fuel cycle. The stability of the original host rock and the flow of groundwater will be perturbed by the thermal disturbances from the waste. So the heater experiment at a depth of 90 m below the surface was carried out to study the conduction of decay heat. For measuring the thermal conductivity of propylite rock mass, a cylindrical heater and 13 thermocouples were inserted in 6 boreholes. The power output of the heater was kept at 880 W constant during the experimental periods of 61 days. From the observed temperature rise around the heater, the thermal conductivity 2.1 W/m 0 C was calculated by steady-state calculation. The value of the rock mass was found to be slightly bigger compared with 1.5 - 1.6 W/m 0 C of core samples. (author)

  5. Insulator-protected mechanically controlled break junctions for measuring single-molecule conductance in aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Muthusubramanian, N.; Zant, H. S. J. van der [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Galan, E.; Maity, C.; Eelkema, R.; Grozema, F. C. [Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft (Netherlands)

    2016-07-04

    We present a method to fabricate insulated gold mechanically controlled break junctions (MCBJ) by coating the metal with a thin layer of aluminum oxide using plasma enhanced atomic layer deposition. The Al{sub 2}O{sub 3} thickness deposited on the MCBJ devices was varied from 2 to 15 nm to test the suppression of leakage currents in deionized water and phosphate buffered saline. Junctions coated with a 15 nm thick oxide layer yielded atomically sharp electrodes and negligible conductance counts in the range of 1 to 10{sup −4} G{sub 0} (1 G{sub 0} = 77 μS), where single-molecule conductances are commonly observed. The insulated devices were used to measure the conductance of an amphiphilic oligophenylene ethynylene derivative in deionized water.

  6. Insulator-protected mechanically controlled break junctions for measuring single-molecule conductance in aqueous environments

    Science.gov (United States)

    Muthusubramanian, N.; Galan, E.; Maity, C.; Eelkema, R.; Grozema, F. C.; van der Zant, H. S. J.

    2016-07-01

    We present a method to fabricate insulated gold mechanically controlled break junctions (MCBJ) by coating the metal with a thin layer of aluminum oxide using plasma enhanced atomic layer deposition. The Al2O3 thickness deposited on the MCBJ devices was varied from 2 to 15 nm to test the suppression of leakage currents in deionized water and phosphate buffered saline. Junctions coated with a 15 nm thick oxide layer yielded atomically sharp electrodes and negligible conductance counts in the range of 1 to 10-4 G0 (1 G0 = 77 μS), where single-molecule conductances are commonly observed. The insulated devices were used to measure the conductance of an amphiphilic oligophenylene ethynylene derivative in deionized water.

  7. Turbulence Measurements from a Moored Platform at Mid-Depth in a Swift Tidal Channel

    Science.gov (United States)

    Hay, Alex; Lueck, Rolf; Wolk, Fabian; McMillan, Justine

    2014-05-01

    Results are presented from a turbulence experiment with a 3-m long streamlined floatation body, instrumented with velocity shear probes, fast-response thermistors, a 1 MHz Acoustic Doppler Current Profiler (AD2CP), and an Acoustic Doppler Velocimeter (ADV). The system was deployed over seven tidal cycles at mid-depth in a 30-m deep tidal channel in the lower Bay of Fundy, Canada. Peak flow speeds exceeded 2 m s-1, and while 10-min time scale average speeds were similar between ebb and flood, the variances were markedly higher during flood. Turbulent kinetic energy (TKE) dissipation rates measured with the shear probes exhibit a pronounced flood/ebb contrast: O(10-4) W kg-1 peak values during flood, but lower by an order of magnitude during ebb. Dissipation rates follow u3 scaling over a wide range of flow speeds between 0.5 and 2.5 m s-1. Below 0.5 m s-1 an asymmetry in the mounting arrangement caused the floatation body to pitch upward, biasing the measured dissipation values high. The ADV on the platform registered mean speed - used to implement Taylor's hypothesis - which was corroborated with the platform-mounted ADCP. Additional ADCPs were also deployed on a nearby bottom pod, sampling at turbulence resolving rates - up to 8 Hz. Comparisons between the shear probe and acoustic estimates of the TKE spectrum and dissipation rate - at comparable depths - are presented.

  8. Measurement of the top quark mass with the template method in the [Formula: see text] channel using ATLAS data.

    Science.gov (United States)

    Aad, G; Abbott, B; Abdallah, J; Abdelalim, A A; Abdesselam, A; Abdinov, O; Abi, B; Abolins, M; AbouZeid, O S; Abramowicz, H; Abreu, H; Acerbi, E; Acharya, B S; Adamczyk, L; Adams, D L; Addy, T N; Adelman, J; Aderholz, M; Adomeit, S; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, J A; Aharrouche, M; Ahlen, S P; Ahles, F; Ahmad, A; Ahsan, M; Aielli, G; Akdogan, T; Åkesson, T P A; Akimoto, G; Akimov, A V; Akiyama, A; Alam, M S; Alam, M A; Albert, J; Albrand, S; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alison, J; Aliyev, M; Allbrooke, B M M; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amaral, P; Amelung, C; Ammosov, V V; Amorim, A; Amorós, G; Amram, N; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Andrieux, M-L; Anduaga, X S; Angerami, A; Anghinolfi, F; Anisenkov, A; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoun, S; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Arfaoui, S; Arguin, J-F; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnault, C; Artamonov, A; Artoni, G; Arutinov, D; Asai, S; Asfandiyarov, R; Ask, S; Åsman, B; Asquith, L; Assamagan, K; Astbury, A; Astvatsatourov, A; Aubert, B; Auge, E; Augsten, K; Aurousseau, M; Avolio, G; Avramidou, R; Axen, D; Ay, C; Azuelos, G; Azuma, Y; Baak, M A; Baccaglioni, G; Bacci, C; Bach, A M; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Badescu, E; Bagnaia, P; Bahinipati, S; Bai, Y; Bailey, D C; Bain, T; Baines, J T; Baker, O K; Baker, M D; Baker, S; Banas, E; Banerjee, P; Banerjee, Sw; Banfi, D; Bangert, A; Bansal, V; Bansil, H S; Barak, L; Baranov, S P; Barashkou, A; Barbaro Galtieri, A; Barber, T; Barberio, E L; Barberis, D; Barbero, M; Bardin, D Y; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Barrillon, P; Bartoldus, R; Barton, A E; Bartsch, V; Bates, R L; Batkova, L; Batley, J R; Battaglia, A; Battistin, M; Bauer, F; Bawa, H S; Beale, S; Beare, B; Beau, T; Beauchemin, P H; Beccherle, R; Bechtle, P; Beck, H P; Becker, S; Beckingham, M; Becks, K H; Beddall, A J; Beddall, A; Bedikian, S; Bednyakov, V A; Bee, C P; Begel, M; Behar Harpaz, S; Behera, P K; Beimforde, M; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellina, F; Bellomo, M; Belloni, A; Beloborodova, O; Belotskiy, K; Beltramello, O; Ben Ami, S; Benary, O; Benchekroun, D; Benchouk, C; Bendel, M; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez Garcia, J A; Benjamin, D P; Benoit, M; Bensinger, J R; Benslama, K; Bentvelsen, S; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Berglund, E; Beringer, J; Bernat, P; Bernhard, R; Bernius, C; Berry, T; Bertella, C; Bertin, A; Bertinelli, F; Bertolucci, F; Besana, M I; Besson, N; Bethke, S; Bhimji, W; Bianchi, R M; Bianco, M; Biebel, O; Bieniek, S P; Bierwagen, K; Biesiada, J; Biglietti, M; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Biscarat, C; Bitenc, U; Black, K M; Blair, R E; Blanchard, J-B; Blanchot, G; Blazek, T; Blocker, C; Blocki, J; Blondel, A; Blum, W; Blumenschein, U; Bobbink, G J; Bobrovnikov, V B; Bocchetta, S S; Bocci, A; Boddy, C R; Boehler, M; Boek, J; Boelaert, N; Bogaerts, J A; Bogdanchikov, A; Bogouch, A; Bohm, C; Boisvert, V; Bold, T; Boldea, V; Bolnet, N M; Bona, M; Bondarenko, V G; Bondioli, M; Boonekamp, M; Booth, C N; Bordoni, S; Borer, C; Borisov, A; Borissov, G; Borjanovic, I; Borri, M; Borroni, S; Bortolotto, V; Bos, K; Boscherini, D; Bosman, M; Boterenbrood, H; Botterill, D; Bouchami, J; Boudreau, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Bousson, N; Boveia, A; Boyd, J; Boyko, I R; Bozhko, N I; Bozovic-Jelisavcic, I; Bracinik, J; Braem, A; Branchini, P; Brandenburg, G W; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brelier, B; Bremer, J; Brenner, R; Bressler, S; Breton, D; Britton, D; Brochu, F M; Brock, I; Brock, R; Brodbeck, T J; Brodet, E; Broggi, F; Bromberg, C; Bronner, J; Brooijmans, G; Brooks, W K; Brown, G; Brown, H; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Buanes, T; Buat, Q; Bucci, F; Buchanan, J; Buchanan, N J; Buchholz, P; Buckingham, R M; Buckley, A G; Buda, S I; Budagov, I A; Budick, B; Büscher, V; Bugge, L; Bulekov, O; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Bussey, P; Buszello, C P; Butin, F; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Buttinger, W; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G; Calfayan, P; Calkins, R; Caloba, L P; Caloi, R; Calvet, D; Calvet, S; Camacho Toro, R; Camarri, P; Cambiaghi, M; Cameron, D; Caminada, L M; Campana, S; Campanelli, M; Canale, V; Canelli, F; Canepa, A; Cantero, J; Capasso, L; Capeans Garrido, M D M; Caprini, I; Caprini, M; Capriotti, D; Capua, M; Caputo, R; Caramarcu, C; Cardarelli, R; Carli, T; Carlino, G; Carminati, L; Caron, B; Caron, S; Carrillo Montoya, G D; Carter, A A; Carter, J R; Carvalho, J; Casadei, D; Casado, M P; Cascella, M; Caso, C; Castaneda Hernandez, A M; Castaneda-Miranda, E; Castillo Gimenez, V; Castro, N F; Cataldi, G; Cataneo, F; Catinaccio, A; Catmore, J R; Cattai, A; Cattani, G; Caughron, S; Cauz, D; Cavalleri, P; Cavalli, D; Cavalli-Sforza, M; Cavasinni, V; Ceradini, F; Cerqueira, A S; Cerri, A; Cerrito, L; Cerutti, F; Cetin, S A; Cevenini, F; Chafaq, A; Chakraborty, D; Chan, K; Chapleau, B; Chapman, J D; Chapman, J W; Chareyre, E; Charlton, D G; Chavda, V; Chavez Barajas, C A; Cheatham, S; Chekanov, S; Chekulaev, S V; Chelkov, G A; Chelstowska, M A; Chen, C; Chen, H; Chen, S; Chen, T; Chen, X; Cheng, S; Cheplakov, A; Chepurnov, V F; Cherkaoui El Moursli, R; Chernyatin, V; Cheu, E; Cheung, S L; Chevalier, L; Chiefari, G; Chikovani, L; 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Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhuravlov, V; Zieminska, D; Zimmermann, R; Zimmermann, S; Zimmermann, S; Ziolkowski, M; Zitoun, R; Živković, L; Zmouchko, V V; Zobernig, G; Zoccoli, A; Zolnierowski, Y; Zsenei, A; Zur Nedden, M; Zutshi, V; Zwalinski, L

    The top quark mass has been measured using the template method in the [Formula: see text] channel based on data recorded in 2011 with the ATLAS detector at the LHC. The data were taken at a proton-proton centre-of-mass energy of [Formula: see text] and correspond to an integrated luminosity of 1.04 fb -1 . The analyses in the e +jets and μ +jets decay channels yield consistent results. The top quark mass is measured to be m top =174.5±0.6 stat ±2.3 syst GeV.

  9. Four-point probe measurements of a direct current potential drop on layered conductive cylinders

    International Nuclear Information System (INIS)

    Lu, Yi; Bowler, John R

    2012-01-01

    We have determined the steady state electric field due to direct current flowing via point contacts at the cylindrical surface of a uniformly layered conductive rod of finite length. The solution allows one to use four-point probe potential drop measurements to estimate the conductivity or thickness of the layer assuming that the other parameters are known. The electrical potential in the rod has a zero radial derivative at its surface except at the injection and extractions points. This means that the required solution can be expressed in terms of a Green’s function satisfying a Neumann boundary condition. Four-point measurements have been made to demonstrate the validity of theoretical results. (paper)

  10. Four-point probe measurements of a direct current potential drop on layered conductive cylinders

    Science.gov (United States)

    Lu, Yi; Bowler, John R.

    2012-11-01

    We have determined the steady state electric field due to direct current flowing via point contacts at the cylindrical surface of a uniformly layered conductive rod of finite length. The solution allows one to use four-point probe potential drop measurements to estimate the conductivity or thickness of the layer assuming that the other parameters are known. The electrical potential in the rod has a zero radial derivative at its surface except at the injection and extractions points. This means that the required solution can be expressed in terms of a Green’s function satisfying a Neumann boundary condition. Four-point measurements have been made to demonstrate the validity of theoretical results.

  11. Nuclear magnetic resonance and electrical conductivity measurements of diffusion and disorder in LiBr

    International Nuclear Information System (INIS)

    Hamann, H.; Reininghaus, J.; Richtering, H.

    1980-01-01

    Electrical conductivity and nuclear magnetic relaxation rates were measured with pure and doped LiBr between 400 K and the melting point (824 K). Prevalent intrinsic disorder was observed down to 470 K. The degree of thermal disorder is 5 X 10 -7 at 470 K and 5 X 10 -3 at the melting point. From the relaxation rates of 7 Li, which are caused by Li-diffusion and nuclear dipole interaction, mean jump frequencies of the cations are derived. Conductivities calculated from these frequencies for a jump process via neighbouring cation vacancies are in perfect agreement with directly measured conductivities. From relaxation rates of 81 Br with MgBr 2 -doped crystals jump frequencies of vacancies were obtained which are again in good agreement with those derived from the conductivity data. From motional narrowing of the 81 Br absorption line the jump frequency of the anions is obtained, which is much smaller than for the cations. Since this motional narrowing is not influenced by any doping, it is concluded that anion transport mainly occurs via pairs of cation and anion vacancies. (Auth.)

  12. USING HOT WIRE TECHNIQUE FOR MEASURING THERMAL CONDUCTIVITY OF INFUSIONS OF ORGANIC AND CONVENTIONAL COFFEE

    Directory of Open Access Journals (Sweden)

    Fernando Gordillo-Delgado

    2016-07-01

    Full Text Available The technique of hot wire, a versatile method of low cost and high accuracy for measuring the thermal conductivity of fluids through the increasing temperature of a wire that is immersed into the liquid and between its ends a potential difference is abruptly applied. Using well-known conductivity liquids: water, ethylene glycol and glycerine, the system was tested and calibrated. In this work, this procedure was used to measure the thermal conductivity of the infusion samples of organic and conventional coffee. The same roast degree of the beans was verified with a colorimeter and the preparation was made by pressing 22g of coffee powder in 110mL of water. The obtained data were subjected to Analysis of Variance (ANOVA and this confirmed that the differences in the thermophysical parameter in the two samples are significant with a confidence level of 95\\%. On this way, it was proved that the thermal conductivity value of the coffee infusion allows differentiate between organic and conventional coffee.

  13. Mobile TDR for geo-referenced measurement of soil water content and electrical conductivity

    DEFF Research Database (Denmark)

    Thomsen, Anton; Schelde, Kirsten; Drøscher, Per

    2007-01-01

    The development of site-specific crop management is constrained by the availability of sensors for monitoring important soil and crop related conditions. A mobile time-domain reflectometry (TDR) unit for geo-referenced soil measurements has been developed and used for detailed mapping of soil wat...... analysis of the soil water measurements, recommendations are made with respect to sampling strategies. Depending on the variability of a given area, between 15 and 30 ha can be mapped with respect to soil moisture and electrical conductivity with sufficient detail within 8 h...

  14. Alkalisation agent measurement with differential conductivity method in secondary water system

    International Nuclear Information System (INIS)

    Wuhrmann, Peter; Lendi, Marco

    2012-09-01

    Besides ammonia hydroxide, also morpholine and ethanol-amine (ETA) are mainly used as a pH regulating agent on the secondary water side [1]. The concentration of the alkalisation agent can only be calculated if the chemical composition in the sample is known [2]. Therefore, for a reliable alkalisation agent measurement, there are three major steps to take: A reliable specific and (degassed) acid conductivity measurement, pH calculation and the selection of the chemical model for concentration calculation of the alkalisation agent (authors)

  15. Surface-sensitive conductivity measurement using a micro multi-point probe approach

    DEFF Research Database (Denmark)

    Perkins, Edward; Barreto, Lucas; Wells, Justin

    2013-01-01

    An instrument for microscale electrical transport measurements in ultra-high vacuum is presented. The setup is constructed around collinear lithographically-created multi-point probes with a contact spacing down to 500 nm. Most commonly, twelve-point probes are used. These probes are approached...... measurements with an equidistant four-point probe for a wide range of contact spacings. In this way, it is possible to distinguish between bulk-like and surface-like conduction. The paper describes the design of the instrument and the approach to data and error analysis. Application examples are given...

  16. American National Standard: for safety in conducting subcritical neutron-multiplication measurements in-situ

    International Nuclear Information System (INIS)

    1983-01-01

    This standard provides safety guidance for conducting subcritical neutron-multiplication measurements where physical protection of personnel against the consequences of a criticality accident is not provided. The objectives of in-situ measurements are either to confirm an adequate safety margin or to improve an estimate of such a margin. The first objective may constitute a test of the criticality safety of a design that is based on calculations. The second may effect improved operating conditions by reducing the uncertainty of safety margins and providing guidance to new designs

  17. Ion conducting behavior in secondary battery materials detected by quasi-elastic neutron scattering measurements

    International Nuclear Information System (INIS)

    Nozaki, Hiroshi

    2014-01-01

    Ionic conducting behaviors in secondary battery materials, i.e. cathode and solid electrolyte, were studied with quasi-elastic neutron scattering (QENS) measurements. Although the incoherent scattering length for Li and Na is lower by two orders of magnitude than that for H, the QENS spectra were clearly detected using the combination of an intense neutron source and a low background spectrometer. The fundamental parameters, such as, the activation energy, the jump distance, and the diffusion coefficient were obtained by analyzing QENS spectra. These parameters are consistent with the previous results estimated by muon-spin relaxation (μSR) measurements and first principles calculations. (author)

  18. Summary of round robin measurements of radiation induced conductivity in Wesgo AL995 alumina

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    This existing data on radiation induced conductivity (RIC) measurements performed on the same heat of the IEA reference ceramic insulator are summarized. Six different sets of RIC measurements have been performed on Wesgo AL995 at dose rates between 10 Gy/s and 1 MGy/s. In general, good agreement was obtained between the different groups of researchers. The data indicate that the RIC at a test temperature of 400-500{degrees}C is approximately linear with ionizing dose rate up to {approximately}1000 Gy/s, and exhibits an approximately square root dependence on dose rate between 1 kGy/s and 1 MGy/s.

  19. Estimating Concentrations of Road-Salt Constituents in Highway-Runoff from Measurements of Specific Conductance

    Science.gov (United States)

    Granato, Gregory E.; Smith, Kirk P.

    1999-01-01

    Discrete or composite samples of highway runoff may not adequately represent in-storm water-quality fluctuations because continuous records of water stage, specific conductance, pH, and temperature of the runoff indicate that these properties fluctuate substantially during a storm. Continuous records of water-quality properties can be used to maximize the information obtained about the stormwater runoff system being studied and can provide the context needed to interpret analyses of water samples. Concentrations of the road-salt constituents calcium, sodium, and chloride in highway runoff were estimated from theoretical and empirical relations between specific conductance and the concentrations of these ions. These relations were examined using the analysis of 233 highwayrunoff samples collected from August 1988 through March 1995 at four highway-drainage monitoring stations along State Route 25 in southeastern Massachusetts. Theoretically, the specific conductance of a water sample is the sum of the individual conductances attributed to each ionic species in solution-the product of the concentrations of each ion in milliequivalents per liter (meq/L) multiplied by the equivalent ionic conductance at infinite dilution-thereby establishing the principle of superposition. Superposition provides an estimate of actual specific conductance that is within measurement error throughout the conductance range of many natural waters, with errors of less than ?5 percent below 1,000 microsiemens per centimeter (?S/cm) and ?10 percent between 1,000 and 4,000 ?S/cm if all major ionic constituents are accounted for. A semi-empirical method (adjusted superposition) was used to adjust for concentration effects-superposition-method prediction errors at high and low concentrations-and to relate measured specific conductance to that calculated using superposition. The adjusted superposition method, which was developed to interpret the State Route 25 highway-runoff records, accounts for

  20. In Situ Monitoring of Dispersion Dynamics of Carbon Nanotubes during Sonication Using Electrical Conductivity Measurements

    Directory of Open Access Journals (Sweden)

    Syed Sadiq Ali

    2015-01-01

    Full Text Available The main challenge in the fabrication of carbon nanotube- (CNT- based composite materials is the optimization of the sonication time in order to obtain homogenous and uniform dispersion of CNTs. Past studies mostly relied on postprocessing characterization techniques to address this issue. In the present, however, in situ monitoring of dispersion dynamics of CNTs in distilled water is carried out using instantaneous conductivity measurements. Using a computer controlled data acquisition system, the time evolution of the solution conductivity was carefully recorded. The data were then used to evaluate the intensity of turbulent fluctuations, which clearly highlighted the existence of three distinct sonication phases. During the first phase, the conductivity fluctuations initially increased attaining ultimately a maximum, thus indicating the occurrence of large agglomerates of CNTs. During the second phase of sonication, the solution conductivity showed a rather steep increase while fluctuations steadily declined. This phenomenon can be attributed to the breakdown of large CNT agglomerates, resulting in greater dispersion homogeneity of CNTs. During the third phase, after almost 650 kJ/L of sonication energy, the conductivity increase was almost negligible. The fluctuation intensity also remained constant during this phase signifying that the further sonication was no longer required.

  1. Thermal separation of soil particles from thermal conductivity measurement under various air pressures.

    Science.gov (United States)

    Lu, Sen; Ren, Tusheng; Lu, Yili; Meng, Ping; Zhang, Jinsong

    2017-01-05

    The thermal conductivity of dry soils is related closely to air pressure and the contact areas between solid particles. In this study, the thermal conductivity of two-phase soil systems was determined under reduced and increased air pressures. The thermal separation of soil particles, i.e., the characteristic dimension of the pore space (d), was then estimated based on the relationship between soil thermal conductivity and air pressure. Results showed that under both reduced and increased air pressures, d estimations were significantly larger than the geometrical mean separation of solid particles (D), which suggested that conductive heat transfer through solid particles dominated heat transfer in dry soils. The increased air pressure approach gave d values lower than that of the reduced air pressure method. With increasing air pressure, more collisions between gas molecules and solid surface occurred in micro-pores and intra-aggregate pores due to the reduction of mean free path of air molecules. Compared to the reduced air pressure approach, the increased air pressure approach expressed more micro-pore structure attributes in heat transfer. We concluded that measuring thermal conductivity under increased air pressure procedures gave better-quality d values, and improved soil micro-pore structure estimation.

  2. Thermal conductivity of a film of single walled carbon nanotubes measured with infrared thermal imager

    Science.gov (United States)

    Feng, Ya; Inoue, Taiki; Xiang, Rong; Chiashi, Shohei; Maruyama, Shigeo

    Heat dissipation has restricted the modern miniaturization trend with the development of electronic devices. Theoretically proven to be with high axial thermal conductivity, single walled carbon nanotubes (SWNT) have long been expected to cool down the nanoscale world. Even though the tube-tube contact resistance limits the capability of heat transfer of the bulk film, the high intrinsic thermal conductivity of SWNT still glorify the application of films of SWNT network as a thermal interface material. In this work, we proposed a new method to straightly measure the thermal conductivity of SWNT film. We bridged two cantilevered Si thin plate with SWNT film, and kept a steady state heat flow in between. With the infrared camera to record the temperature distribution, the Si plates with known thermal conductivity can work as a reference to calculate the heat flux going through the SWNT film. Further, the thermal conductivity of the SWNT film can be obtained through Fourier's law after deducting the effect of thermal radiation. The sizes of the structure, the heating temperature, the vacuum degree and other crucial impact factors are carefully considered and analyzed. The author Y. F. was supported through the Advanced Integration Science Innovation Education and Research Consortium Program by the Ministry of Education, Culture, Sport, Science and Technology.

  3. Measuring service quality trade-offs in Asian distribution channels: A multi-layer perspective

    NARCIS (Netherlands)

    Wetzels, M.G.M.; Ruyter, de J.C.; Lemmink, J.G.A.M.

    2000-01-01

    In international marketing channels customer service has become an important factor in supplier and purchase decisions. In evaluating supplier performance several trade-offs are taken into account by actors operating at various channel levels. These are trade-offs among customer service elements and

  4. Economic and Social Satisfaction : Measurement and Relevance to Marketing Channel Relationships

    NARCIS (Netherlands)

    Geyskens, I.; Steenkamp, J.E.B.M.

    2000-01-01

    We demonstrate the critical need to recognize the presence of two different types of satisfaction for effective channel governance—economic satisfaction, that is, a channel member’s evaluation of the economic outcomes that flow from the relationship with its partner, and social satisfaction, a

  5. Measures of skin conductance and heart rate in alcoholic men and women during memory performance

    Directory of Open Access Journals (Sweden)

    Kayle S. Sawyer

    2015-05-01

    Full Text Available We examined abnormalities in physiological responses to emotional stimuli associated with long-term chronic alcoholism. Skin conductance responses (SCR and heart rate (HR responses were measured in 32 abstinent alcoholic (ALC and 30 healthy nonalcoholic (NC men and women undergoing an emotional memory task in an MRI scanner. The task required participants to remember the identity of two emotionally-valenced faces presented at the onset of each trial during functional magnetic resonance imaging (fMRI scanning. After viewing the faces, participants saw a distractor image (an alcoholic beverage, nonalcoholic beverage, or scrambled image followed by a single probe face. The task was to decide whether the probe face matched one of the two encoded faces. Skin conductance measurements (before and after the encoded faces, distractor, and probe were obtained from electrodes on the index and middle fingers on the left hand. HR measurements (beats per minute before and after the encoded faces, distractor, and probe were obtained by a pulse oximeter placed on the little finger on the left hand. We expected that, relative to NC participants, the ALC participants would show reduced SCR and HR responses to the face stimuli, and that we would identify greater reactivity to the alcoholic beverage stimuli than to the distractor stimuli unrelated to alcohol. While the beverage type did not differentiate the groups, the ALC group did have reduced skin conductance and HR responses to elements of the task, as compared to the NC group.

  6. Measurement of the ttbar production cross section in the MET+jets channel at CDF

    International Nuclear Information System (INIS)

    Compostella, Gabriele; INFN, Trento

    2008-01-01

    This thesis is focused on an inclusive search of the t(bar t) → E T + jets decay channel by means of neural network tools in proton antiproton collisions at √s = 1.96 TeV recorded by the Collider Detector at Fermilab (CDF). At the Tevatron p(bar p) collider top quarks are mainly produced in pairs through quark-antiquark annihilation and gluon-gluon fusion processes; in the Standard Model description, the top quark then decays to a W boson and a b quark almost 100% of the times, so that its decay signatures are classified according to the W decay modes. When only one W decays leptonically, the t(bar t) event typically contains a charged lepton, missing transverse energy due to the presence of a neutrino escaping from the detector, and four high transverse momentum jets, two of which originate from b quarks. In this thesis we describe a t(bar t) production cross section measurement which uses data collected by a 'multijet' trigger, and selects this kind of top decays by requiring a high-P T neutrino signature and by using an optimized neural network to discriminate top quark pair production from backgrounds. In Chapter 1, a brief review of the Standard Model of particle physics will be discussed, focusing on top quark properties and experimental signatures. In Chapter 2 will be presented an overview of the Tevatron accelerator chain that provides p(bar p) collisions at the center-of-mass energy of √s = 1.96 TeV, and proton and antiproton beams production procedure will be discussed. The CDF detector and its components and subsystems used for the study of p(bar p) collisions provided by the Tevatron will be described in Chapter 3. Chapter 4 will detail the reconstruction procedures used in CDF to detect physical objects exploiting the features of the different detector subsystems. Chapter 5 will provide an overview of the main concepts regarding Artificial Neural Networks, one of the most important tools we will use in the analysis. Chapter 6 will be devoted to

  7. Simultaneous measurement of thermal conductivity, thermal diffusivity and prediction of effective thermal conductivity of porous consolidated igneous rocks at room temperature

    International Nuclear Information System (INIS)

    Aurangzeb; Ali, Zulqurnain; Gurmani, Samia Faiz; Maqsood, Asghari

    2006-01-01

    Thermal conductivity, thermal diffusivity and heat capacity per unit volume of porous consolidated igneous rocks have been measured, simultaneously by Gustafsson's probe at room temperature and normal pressure using air as saturant. Data are presented for eleven samples of dunite, ranging in porosity from 0.130 to 0.665% by volume, taken from Chillas near Gilgit, Pakistan. The porosity and density parameters have been measured using American Society of Testing and Materials (ASTM) standards at ambient conditions. The mineral composition of samples has been analysed from their thin sections (petrography). An empirical model to predict the thermal conductivity of porous consolidated igneous rocks is also proposed. The thermal conductivities are predicted by some of the existing models along with the proposed one. It is observed that the values of effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 6%

  8. Measurement of the Higgs boson coupling properties in the diphoton, ZZ and WW decay channels using the ATLAS detector

    CERN Document Server

    Gupta, Ruchi; The ATLAS collaboration

    2017-01-01

    The coupling properties of the Higgs boson are studied in the diphoton, ZZ to four-lepton decay channels using 36.1 fb$^{-1}$ of $pp$ collision data from the LHC at a centre-of-mass energy of 13 TeV collected by the ATLAS detector. Measurements of simplified template cross sections, designed to measure the different Higgs boson production processes in specific regions of phase space, are reported for diphoton and four-leptons decay channels. Cross sections for different higgs boson production modes are interpreted in terms of coupling modifiers. In ZZ decay channel, the tensor structure of the Higgs boson couplings is studied using an effective Lagrangian approach for the description of interactions beyond the Standard Model.

  9. Heteromeric K(v)7.2/7.3 Channels Differentially Regulate Action Potential Initiation and Conduction in Neocortical Myelinated Axons

    NARCIS (Netherlands)

    Battefeld, Arne; Tran, Baouyen T.; Gavrilis, Jason; Cooper, Edward C.; Kole, Maarten H. P.

    2014-01-01

    Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of K(v)7 potassium channels and voltage-gated sodium (Na-v) channels in the

  10. Property measurements of the Higgs boson in the diphoton decay channel with the ATLAS detector at the LHC

    CERN Document Server

    ATLAS Collaboration; The ATLAS collaboration

    2017-01-01

    This poster presents the latest measurements of the Higgs boson properties measured in the H → γγ decay channel using 36.1fb −1 of proton-proton collision data taken at √ s = 13TeV by the ATLAS experiment at the LHC. Fiducial and differential cross section measurements are presented in a variety of phase space regions and as a function of several kinematic variables, to be compared with the Standard Model Higgs predicted distributions.

  11. Multi-channel Langmuir-probe and H[alpha]-measurements of edge fluctuations on ASDEX

    Energy Technology Data Exchange (ETDEWEB)

    Niedermeyer, H; Carlson, A; Endler, M; Giannone, L.; Rudyj, A; Theimer, G [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

    1991-01-01

    The anomalous transport observed in tokamaks is caused by turbulent fluctuations, the nature of which is still poorly understood. Diagnostic difficulties are one major reason for this lack of understanding, at least with respect to the bulk plasma. The plasma edge, however, is accessible by several diagnostics permitting localized measurements of different parameters with good spatial and temporal resolution. For this reason one can hope to obtain enough information about edge fluctuations to permit the development of theoretical models. Different ranges of plasma parameters and the lack of closed magnetic surfaces distinguish this plasma zone from the bulk plasma. Edge turbulence might well involve other mechanisms than the turbulence in the bulk. Although transport in the bulk plasma receives more attention transport in the edge plasma and edge physics are very relevant for reactor design. The realistic hope to find a solution and the importance of the problem for the next step in fusion research are reasons for the strong effort in this field on many tokamaks. Like in many limiter tokamaks Langmuir probes were used in the ASDEX divertor device for measurements of the floating potential and of the ion saturation current. Under certain assumptions the electron density and the plasma potential can be derived from these data. Observation of the H[alpha]-light emitted from the edge in the vicinity of a neutral gas source yields information about the electron density. While probe measurements are more suitable for quantitative evaluations including the calculation of the local particle flux the H[alpha]-method is not calibrated and integrates radially over the edge. It is however applicable in situations where probes fail because of excessive heat load. With 16-channel arrays both methods permit spatial correlations and wavenumber spectra to be determined without any further assumptions. (author) 4 refs., 2 figs.

  12. A passive guard for low thermal conductivity measurement of small samples by the hot plate method

    International Nuclear Information System (INIS)

    Jannot, Yves; Godefroy, Justine; Degiovanni, Alain; Grigorova-Moutiers, Veneta

    2017-01-01

    Hot plate methods under steady state conditions are based on a 1D model to estimate the thermal conductivity, using measurements of the temperatures T 0 and T 1 of the two sides of the sample and of the heat flux crossing it. To be consistent with the hypothesis of the 1D heat flux, either a hot plate guarded apparatus is used, or the temperature is measured at the centre of the sample. On one hand the latter method can be used only if the ratio thickness/width