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Sample records for coupled contactless conductivity

  1. Determination of mono-, di-, and oligosaccharides by capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    do Lago, Claudimir Lucio; Nogueira, Thiago; Blanes, Lucas; Saito, Renata Mayumi

    2013-01-01

    Saccharides and chitooligosaccharides can be separated in electrophoretic conditions by raising the pH of the medium, which renders the corresponding alcoholate forms. These anionic species can be separated and detected with capacitively coupled contactless conductivity detection as negative peaks because of their low mobilities when compared to the hydroxyl mobility, which is the main co-ion in the background electrolyte. Three methods for different matrixes are presented in this chapter.

  2. Determination of pharmaceuticals classified as emerging pollutants using capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Quek, Ngee Mien; Law, Wai Siang; Lau, Hiu Fung; Zhao, Jian Hong; Hauser, Peter C; Li, Sam Fong Yau

    2008-09-01

    A study on the simultaneous separation of 13 pharmaceutical products by capillary electrophoresis with capacitively coupled contactless conductivity detection was presented. The parameters of the background electrolyte, such as pH, organic additives as well as types and concentrations of cyclodextrins (CD) were studied. The optimal separation conditions were achieved with a background electrolyte consisting of 9 mM Tris/5 mM lactic acid at pH 8.0, containing 5% n-propanol, 0.025% gamma-CD, 0.075% hydroxyl-beta-CD and 0.15% dimethyl-beta-CD. Limits of detections ranged from 61 to 1676 microg/L (S/N=3) and the relative standard deviations for migration time and peak area were below 2 and 6%, respectively. This demonstrated the potential of the capillary electrophoresis-capacitively coupled contactless conductivity detection method for biomedical and environmental analysis, as shown in the determination of pharmaceuticals identified as emerging pollutants in water samples.

  3. Metalless electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips.

    PubMed

    Duarte Junior, Gerson F; Fracassi da Silva, José Alberto; Mendonça Francisco, Kelliton José; do Lago, Claudimir Lucio; Carrilho, Emanuel; Coltro, Wendell K T

    2015-08-01

    This paper describes the use of ionic solutions as sensing electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips. Initially, two channels were engraved in a PMMA holder by using a CO2 laser system and sealed with a thin adhesive membrane. PDMS electrophoresis chips were fabricated by soft lithography and reversibly sealed against the polymer membrane. Different ionic solutions were investigated as metalless electrodes. The electrode channels were filled with KCl solutions prepared in conductivity values from approximately 10 to 40 S/m. The best analytical response was achieved using the KCl solution with 21.9 S/m conductivity (2 mol/L). Besides KCl, we also tested NaCl and LiCl solutions for actuating as detection electrodes. Taking into account the same electrolyte concentration (2 mol/L), the best response was recorded with KCl solution due to its higher ionic conductivity. The optimum operating frequency (400 kHz) and the best sensing electrode (2 mol/L KCl) were used to monitor electrophoretic separations of a mixture containing K(+) , Na(+) , and Li(+) . The use of liquid solutions as sensing electrodes for capacitively coupled contactless conductivity detection measurements has revealed great performance to monitor separations on chip-based devices, avoiding complicated fabrication schemes to include metal deposition and encapsulation of electrodes. The LOD values were estimated to be 28, 40, and 58 μmol/L for K(+) , Na(+) , and Li(+) , respectively, what is comparable to that of conventional metal electrodes. When compared to the use metal electrodes, the proposed approach offers advantages regarding the easiness of fabrication, simplicity, and lower cost per device.

  4. Capacitively coupled contactless conductivity detection with dual top-bottom cell configuration for microchip electrophoresis.

    PubMed

    Mahabadi, Kambiz A; Rodriguez, Isabel; Lim, Chee Y; Maurya, Devendra K; Hauser, Peter C; de Rooij, Nico F

    2010-03-01

    An optimized capacitively coupled contactless conductivity detector for microchip electophoresis is presented. The detector consists of a pair of top-bottom excitation electrodes and a pair of pickup electrodes disposed onto a very thin plastic microfluidic chip. The detection cell formed by the electrodes is completely encased and shielded in a metal housing. These approaches allow for the enhancement of signal coupling and extraction from the detection cell that result in an improved signal-to-noise-ratio and detection sensitivity. The improved detector performance is illustrated by the electrophoretic separation of six cations (NH(4) (+), K(+), Ca(2+), Na(+), Mg(2+), Li(+)) with a detection limit of approximately 0.3 microM and the analysis of the anions (Br(-), Cl(-), NO(2) (-), NO(3) (-), SO(4) (2-), F(-)) with a detection limit of about 0.15 microM. These LODs are significantly improved compared with previous reports using the conventional top-top electrode geometry. The developed system was applied to the analysis of ions in bottled drinking water samples.

  5. Analysis of ecstasy tablets using capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Porto, Suely K S S; Nogueira, Thiago; Blanes, Lucas; Doble, Philip; Sabino, Bruno D; do Lago, Claudimir L; Angnes, Lúcio

    2014-11-01

    A method for the identification of 3,4-methylenedioxymethamphetamine (MDMA) and meta-chlorophenylpiperazine (mCPP) was developed employing capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4) D). Sample extraction, separation, and detection of "Ecstasy" tablets were performed in <10 min without sample derivatization. The separation electrolyte was 20 mm TAPS/Lithium, pH 8.7. Average minimal detectable amounts for MDMA and mCPP were 0.04 mg/tablet, several orders of magnitude lower than the minimum amount encountered in a tablet. Seven different Ecstasy tablets seized in Rio de Janeiro, Brazil, were analyzed by CE-C(4) D and compared against routine gas chromatography-mass spectrometry (GC-MS). The CE method demonstrated sufficient selectivity to discriminate the two target drugs, MDMA and mCPP, from the other drugs present in seizures, namely amphepramone, fenproporex, caffeine, lidocaine, and cocaine. Separation was performed in <90 sec. The advantages of using C(4) D instead of traditional CE-UV methods for in-field analysis are also discussed. © 2014 American Academy of Forensic Sciences.

  6. Authenticity screening of seized whiskey samples using electrophoresis microchips coupled with contactless conductivity detection.

    PubMed

    Rezende, Kariolanda C A; Moreira, Roger Cardoso; Logrado, Lucio Paulo Lima; Talhavini, Márcio; Coltro, Wendell K T

    2016-10-01

    This report describes for the first time the use of microchip electrophoresis (ME) devices integrated with capacitively coupled contactless conductivity detection (C(4) D) to investigate the authenticity of seized whiskey samples, which were probably adulterated by simple dilution with tap water. The proposed microfluidic platform was explored for the monitoring of anionic species (Cl(-) and F(-) ) in both original and tampered samples. The best separations were achieved within 70 s using a running buffer composed of lactic acid and histidine (pH = 5.9). ME-C(4) D devices were used to analyze samples from three different brands (five samples each). Based on the presence of inorganic anions like Cl(-) , F(-) , SO4(2-) and NO2(-) in different amounts, the authenticity of seized whiskeys was compared to original samples. According to the reported data, the proposed microfluidic platform can be useful to help regulatory authorities in the investigation and monitoring of authenticity of commercialized whiskey beverages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Contactless Rotary Electrical Couplings

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki

    2003-01-01

    Rotary electrical couplings based on induction (transformer action) rather than conduction between rotating and stationary circuitry have been invented. These couplings provide an alternative to slip rings and contact brushes. Mechanical imperfections of slip-ring and brush contact surfaces and/or dust particles trapped between these surfaces tend to cause momentary interruptions in electrical contact and thereby give rise to electrical noise. This source of noise can be eliminated in the inductive rotary couplings because no direct contact is necessary for transformer action.

  8. Determination of heavy metal ions by microchip capillary electrophoresis coupled with contactless conductivity detection.

    PubMed

    Liu, Benyan; Zhang, Yi; Mayer, Dirk; Krause, Hans-Joachim; Jin, Qinghui; Zhao, Jianlong; Offenhäusser, Andreas; Xu, Yuansen

    2012-04-01

    An integrated detection circuitry based on a lock-in amplifier was designed for contactless conductivity determination of heavy metals. Combined with a simple-structure electrophoresis microchip, the detection system is successfully utilized for the separation and determination of various heavy metals. The influences of the running buffer and detection conditions on the response of the detector have been investigated. Six millimole 2-morpholinoethanesulfonic acid + histidine were selected as buffer for its stable baseline and high sensitivity. The best signals were recorded with a frequency of 38 kHz and 20 V(pp). The results showed that Mn(2+), Cd(2+), Co(2+), and Cu(2+) can be successfully separated and detected within 100 s by our system. The detection limits for five heavy metals (Mn(2+), Pb(2+), Cd(2+), Co(2+), and Cu(2+)) were determined to range from about 0.7 to 5.4 μM. This microchip system performs a crucial step toward the realization of a simple, inexpensive, and portable analytical device for metal analysis.

  9. A capillary electrophoresis system with dual capacitively coupled contactless conductivity detection and electrospray ionization tandem mass spectrometry.

    PubMed

    Francisco, Kelliton José Mendonça; do Lago, Claudimir Lucio

    2016-07-01

    A commercial system that is comprised of a CE coupled to an ESI triple quadrupole mass spectrometer was equipped with two capacitively coupled contactless conductivity detectors (C(4) Ds). The first C(4) D was positioned inside the original cartridge, and the second C(4) D was positioned as close as possible to the ESI probe entrance by using a 3D-printed support. The C(4) Ds electropherograms were matched to the ESI-MS electropherogram by correcting their timescales by the factor LT /LD , where LT and LD are the total capillary length and the length until the C(4) D, respectively. A general approach for method development supporting the simultaneous conductivity and MS detection is discussed, while application examples are introduced. These examples include the use of C(4) D as a simple device that dismiss the use of an EOF marker, a low-selectivity detector that continuously provide information about unexpected features of the sample, and even a detector that can be more sensitive than ESI-MS. The C(4) D used in this setup proved to have a smaller contribution to the peak broadening than ESI-MS, which allowed that a C(4) D, positioned at 12 cm from the inlet of an 80-cm-long capillary, could be used to foresee position and shape of the peaks being formed 6.8 times slower at the ESI-MS electropherogram.

  10. Simultaneous determination of atenolol and amiloride in pharmaceutical preparations by capillary zone electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Al Azzam, Khaldun M; Saad, Bahruddin; Aboul-Enein, Hassan Y

    2010-09-01

    Capillary zone electrophoresis coupled with a capacitively coupled contactless conductivity detector (CE-C(4)D) has been employed for the determination of atenolol and amiloride in pharmaceutical formulations. Acetic acid (150 mm) was used as background electrolyte. The influence of several factors (detector excitation voltage and frequency, buffer concentration, applied voltage, capillary temperature and injection time) was studied. Non-UV-absorbing L-valine was used as internal standard; the analytes were all separated in less than 7 min. The separation was carried out in normal polarity mode at 28 degrees C, 25 kV and using hydrodynamic injection (25 s). The separation was effected in an uncoated fused-silica capillary (75 microm, i.d. x 52 cm). The CE-C(4)D method was validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. Calibration curves were linear over the range 5-250 microg/mL for the studied analytes. The relative standard deviations of intra- and inter-day migration times and corrected peak areas were less than 6.0%. The method showed good precision and accuracy and was successfully applied to the simultaneous determination of atenolol and amiloride in different pharmaceutical tablet formulations. 2010 John Wiley & Sons, Ltd.

  11. Application of capacitively coupled contactless conductivity as an external detector for zone electrophoresis in poly(dimethylsiloxane) chips.

    PubMed

    Koczka, Péter I; Bodoki, Ede; Gáspár, Attila

    2016-02-01

    In this work, lab-made PDMS microfluidic chips were matched to a capacitively coupled contactless conductivity detector (C(4) D) having external in-plane electrodes (eDAQ, Australia). The advantages of this type of C(4) D are the choice to reversibly place or remove the microchip onto/from the detector and to freely variate the position of the detection (separation length) on the microchip. The thickness of the bottom layer of the PDMS chip was optimized to achieve sensitive detection during the electrophoretic separation. PDMS chips with 100 μm bottom layer used with the C(4) D platform were tested by CZE of a mixture of seven anions and different types of real samples. Using split-flow pressure sample injection and effective length of 6.5 cm, the numbers of theoretical plates were in the range of 4000-6000 (63,000-93,000/m) and the LODs amounted to 3.66-14.7 μmol/L (0.13-2.26 μg/mL) for the studied anions.

  12. Separation and determination of degradation products of acid orange 7 by capillary electrophoresis/capacitively coupled contactless conductivity detector.

    PubMed

    Wang, Xin; Xiong, Ya; Xie, Tianyao; Sharma, Virender K; Tu, Yuting; Yang, Jiannan; Tian, Shuanghong; He, Chun

    2013-07-15

    Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detector (C(4)D) was developed to separate azo-dyestuff acid orange 7 (AO7) and its six degradation products. The analyzed products were sulfamic acid, oxalic acid, benzenesulfonic acid, 4-hydroxybenzene sulfonic acid, phthalic acid, and 4-aminobenzene sulfonic acid. In developing the method, types and concentrations of running buffers, injecting voltage and time, and applied voltage were tested to obtain optimum conditions to analyze target compounds. The separation was successfully achieved within 10 min using a fused-silica capillary under the following conditions: 20 mmol L(-1) acetate acid buffer, electrokinetic injection of -12 kV × 10 s, and applied voltage of -13 kV. The developed method was applied to analyze degradation products in situ during the reaction of AO7 with Fenton reagent (Fe(II)+H2O2 at pH 4.0). Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Study on the potential application of salivary inorganic anions in clinical diagnosis by capillary electrophoresis coupled with contactless conductivity detection.

    PubMed

    Guo, Lin; Wang, Yu; Zheng, Yiliang; Huang, Zhipeng; Cheng, Yiyuan; Ye, Jiannong; Chu, Qingcui; Huang, Dongping

    2016-03-01

    A capillary electrophoresis approach with capacitively coupled contactless conductivity detection method has been developed for the determination of inorganic metabolites (thiocyanate, nitrite and nitrate) in human saliva. Field amplified sample injection, as a simple sample stacking technique, was used in conjunction for online preconcentration of above inorganic anions. A selective separation for the target anions from other coexisting constituents present in saliva could be obtained within 14min in a 10mmol/L His-90mmol/L HAc buffer (pH 3.70) at the separation voltage of -18kV. The limits of detection and limits of quantification of the three analytes were within the range of 3.1-4.9ng/mL (S/N=3) and 10-16ng/mL (S/N=10), respectively. The average recovery data were in the range of 81-108% at three different concentrations. This method provides a simple, rapid and direct approach for metabolite analyses of nitric oxide and cyanide based on noninvasive saliva sample, which presents a potential fast screening tool for clinical test.

  14. Determination of fluoroacetate and fluoride in blood serum by capillary zone electrophoresis using capacitively coupled contactless conductivity detection.

    PubMed

    Vidal, Denis Tadeu Rajh; Augelli, Marcio Antonio; Hotta, Guilherme Minoru; Lopes, Fernando Silva; do Lago, Claudimir Lucio

    2011-04-01

    Fluoroacetate is a highly toxic species naturally found in plants and in commercial products (compound 1080) for population control of several undesirable animal species. However, it is non-selective and toxic to many other animals including humans, and thus its detection is very important for forensic purposes. This paper presents a sensitive and fast method for the determination of fluoroacetate in blood serum using capillary electrophoresis with capacitively coupled contactless conductivity detection. Serum blood samples were treated with ethanol to remove proteins. The samples were analyzed in BGE containing 15 mmol/L histidine and 30 mmol/L gluconic acid (pH 3.85). The calibration curve was linear up to 75 μmol/L (R² =0.9995 for N=12). The detection limit in the blood serum was 0.15 mg/kg, which is smaller than the lethal dose for humans and other animals. Fluoride, a metabolite of the fluoroacetate defluorination, could also be detected for levels greater than 20 μmol/L, when polybrene was used for reversion of the EOF. CTAB and didecyldimethylammonium bromide are not useful for this task because of the severe reduction of the fluoride level. However, no interference was observed for fluoroacetate.

  15. High performance separation of quaternary amines using microchip non-aqueous electrophoresis coupled with contactless conductivity detection.

    PubMed

    Moreira, Roger Cardoso; Lopes, Marilia Sousa; Medeiros Junior, Iris; Coltro, Wendell K T

    2017-05-26

    This study describes the development of an analytical methodology for the separation of quaternary amines using non-aqueous microchip electrophoresis (NAME) coupled with capacitively coupled contactless conductivity detection (C(4)D). All experiments were performed using a commercial microchip electrophoresis system consisting of a C(4)D detector, a high-voltage sequencer and a microfluidic platform to assemble a glass microchip with integrated sensing electrodes. The detection parameters were optimized and the best response was reached applying a 700-kHz sinusoidal wave with 14Vpp excitation voltage. The running electrolyte composition was optimized aiming to achieve the best analytical performance. The mixture containing methanol and acetonitrile at the proportion of 90:10 (v:v) as well as sodium deoxycholate provided separations of ten quaternary amines with high efficiency and baseline resolution. The separation efficiencies ranged from 8.7×10(4) to 3.0×10(5) plates/m. The proposed methodology provided linear response in the concentration range between 50 and 1000μmol/L and limits of detection between 2 and 27μmol/L. The analytical feasibility of the proposed methodology was tested in the determination of quaternary amines in corrosion inhibitor samples often used for coating oil pipelines. Five quaternary amines (dodecyltrimethylammonium chloride, tetradecyltrimetylammonium bromide, cetyltrimethylammonium bromide, tetraoctylammonium bromide and tetradodecylammonium bromide) were successfully detected at concentration levels from 0.07 to 6.45mol/L. The accuracy of the developed methodology was investigated and the achieved recovery values varied from 85 to 122%. Based on the reported data, NAME-C(4)D devices exhibited great potential to provide high performance separations of hydrophobic compounds. The developed methodology can be useful for the analysis of species that usually present strong adsorption on the channel inner walls. Copyright © 2017 Elsevier

  16. Electromembrane extraction of amino acids from body fluids followed by capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Strieglerová, Lenka; Kubáň, Pavel; Boček, Petr

    2011-09-16

    Electromembrane extraction (EME) proved to be a simple and rapid pretreatment method for analysis of amino acids and related compounds in body fluid samples. Body fluids were acidified to the final concentration of 2.5 M acetic acid and served as donor solutions. Amino acids, present as cations in the donor solutions, migrated through a supported liquid membrane (SLM) composed of 1-ethyl-2-nitrobenzene/bis-(2-ethylhexyl)phosphonic acid (85:15 (v/v)) into the lumen of a porous polypropylene hollow fiber (HF) on application of electric field. The HF was filled with 2.5 M acetic acid serving as the acceptor solution. Matrix components in body fluids were efficiently retained on the SLM and did not interfere with subsequent analysis. Capillary electrophoresis with capacitively coupled contactless conductivity detection was used for determination of 17 underivatized amino acids in background electrolyte solution consisting of 2.5 M acetic acid. Parameters of EME, such as composition of SLM, pH and composition of donor and acceptor solution, agitation speed, extraction voltage, and extraction time were studied in detail. At optimized conditions, repeatability of migration times and peak areas of 17 amino acids was better than 0.3% and 13%, respectively, calibration curves were linear in a range of two orders of magnitude (r(2)=0.9968-0.9993) and limits of detection ranged from 0.15 to 10 μM. Endogenous concentrations of 12 amino acids were determined in EME treated human serum, plasma, and whole blood. The method was also suitable for simple and rapid pretreatment and determination of elevated concentrations of selected amino acids, which are markers of severe inborn metabolic disorders. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Monitoring of nitrite, nitrate, chloride and sulfate in environmental samples using electrophoresis microchips coupled with contactless conductivity detection.

    PubMed

    Freitas, Camilla Benevides; Moreira, Roger Cardoso; de Oliveira Tavares, Maria Gizelda; Coltro, Wendell K T

    2016-01-15

    This report describes the development of an analytical methodology on microchip electrophoresis (ME) devices coupled with capacitively coupled contactless conductivity detection (C(4)D) to monitor inorganic anions in environmental samples. The buffer composition as well as detection operating parameters were optimized to achieve the best separation selectivity and detector sensitivity, respectively. Electrophoretic separations of Cl(-), NO3(-), SO4(2-) and NO2(-) were successfully performed within 60s using a running buffer composed of 30mmol L(-1) latic acid and 15mmol L(-1)l-histidine (His). The best detectability levels were found applying a sinusoidal wave with 1100-kHz-frequency and 60-Vpp amplitude. Quantitative analyzes of inorganic anions were carried out in the presence of Cr2O7(2-) ion as internal standard (IS), which ensured great repeatability in terms of migration times (<1%) and peak areas (6.2-7.6%) for thirty consecutive injections. The analytical performance revealed a linear behavior for concentration ranges between 0-120μmol L(-1) (Cl(-), NO2(-) and NO3(-)) and 0-60μmol L(-1) (SO4(2-)) and limits of detection (LODs) varying from 2.0 to 4.9μmol L(-1). The concentration levels of anionic species were determined in aquarium, river and biofertilizer samples with recovery values between 91% and 105%. The nitrification steps associated with conversion of ammonium to nitrite followed by the conversion of nitrite to nitrate were successfully monitored in a simulated environment without fishes during a period of twelve weeks. Lastly, the monitoring of anionic species was carried out during eight weeks in an aquarium environment containing ten fishes from Danio rerio (Ciprynidae). The recorded data revealed the absence of nitrite and a gradual increase on the ammonium and nitrate concentration levels during eight weeks, thus suggesting the direct conversion of ammonium to nitrate. Based on the data herein reported, the proposed analytical methodology

  18. Contactless conductivity detector for microchip capillary electrophoresis

    NASA Technical Reports Server (NTRS)

    Pumera, Martin; Wang, Joseph; Opekar, Frantisek; Jelinek, Ivan; Feldman, Jason; Lowe, Holger; Hardt, Steffen; Svehla, D. (Principal Investigator)

    2002-01-01

    A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The contactless route obviates problems (e.g., fouling, unwanted reactions) associated with the electrode-solution contact, offers isolation of the detection system from high separation fields, does not compromise the separation efficiency, and greatly simplifies the detector fabrication. Relevant experimental variables, such as the frequency and amplitude of the applied ac voltage or the separation voltage, were examined and optimized. The detector performance was illustrated by the separation of potassium, sodium, barium, and lithium cations and the chloride, sulfate, fluoride, acetate, and phosphate anions. The response was linear (over the 20 microM-7 mM range) and reproducible (RSD = 3.4-4.9%; n = 10), with detection limits of 2.8 and 6.4 microM (for potassium and chloride, respectively). The advantages associated with the contactless conductivity detection, along with the low cost of the integrated PMMA chip/detection system, should enhance the power and scope of microfluidic analytical devices.

  19. Contactless conductivity detector for microchip capillary electrophoresis

    NASA Technical Reports Server (NTRS)

    Pumera, Martin; Wang, Joseph; Opekar, Frantisek; Jelinek, Ivan; Feldman, Jason; Lowe, Holger; Hardt, Steffen; Svehla, D. (Principal Investigator)

    2002-01-01

    A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The contactless route obviates problems (e.g., fouling, unwanted reactions) associated with the electrode-solution contact, offers isolation of the detection system from high separation fields, does not compromise the separation efficiency, and greatly simplifies the detector fabrication. Relevant experimental variables, such as the frequency and amplitude of the applied ac voltage or the separation voltage, were examined and optimized. The detector performance was illustrated by the separation of potassium, sodium, barium, and lithium cations and the chloride, sulfate, fluoride, acetate, and phosphate anions. The response was linear (over the 20 microM-7 mM range) and reproducible (RSD = 3.4-4.9%; n = 10), with detection limits of 2.8 and 6.4 microM (for potassium and chloride, respectively). The advantages associated with the contactless conductivity detection, along with the low cost of the integrated PMMA chip/detection system, should enhance the power and scope of microfluidic analytical devices.

  20. Contactless conductivity detector for microchip capillary electrophoresis.

    PubMed

    Pumera, Martin; Wang, Joseph; Opekar, Frantisek; Jelínek, Ivan; Feldman, Jason; Löwe, Holger; Hardt, Steffen

    2002-05-01

    A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The contactless route obviates problems (e.g., fouling, unwanted reactions) associated with the electrode-solution contact, offers isolation of the detection system from high separation fields, does not compromise the separation efficiency, and greatly simplifies the detector fabrication. Relevant experimental variables, such as the frequency and amplitude of the applied ac voltage or the separation voltage, were examined and optimized. The detector performance was illustrated by the separation of potassium, sodium, barium, and lithium cations and the chloride, sulfate, fluoride, acetate, and phosphate anions. The response was linear (over the 20 microM-7 mM range) and reproducible (RSD = 3.4-4.9%; n = 10), with detection limits of 2.8 and 6.4 microM (for potassium and chloride, respectively). The advantages associated with the contactless conductivity detection, along with the low cost of the integrated PMMA chip/detection system, should enhance the power and scope of microfluidic analytical devices.

  1. Capacitively coupled contactless conductivity detection as an alternative detection mode in CE for the analysis of kanamycin sulphate and its related substances.

    PubMed

    El-Attug, Mohamed N; Adams, Erwin; Hoogmartens, Jos; Van Schepdael, Ann

    2011-09-01

    A method was developed to determine simultaneously kanamycin, its related substances and sulphate in kanamycin sulphate using capacitively coupled contactless conductivity detection. Kanamycin is an aminoglycoside antibiotic that lacks a strong UV-absorbing chromophore. Due to its physicochemical properties, CE in combination with capacitively coupled contactless conductivity detection was chosen. The separation method uses a BGE composed of 40 mM 2-(N-morpholino)ethanesulphonic acid monohydrate and 40 mM L-histidine, pH 6.35. A 0.6 mM N-cetyltrimethyl ammonium bromide (CTAB) solution was added as electroosmotic flow modifier in a concentration below the critical micellar concentration (CMC). Ammonium acetate 50 mg/L was used as internal standard. In total, 30 kV was applied in reverse polarity on a fused-silica capillary (65/41 cm; 75 μm id). The optimized separation was obtained in less than 6 min with good linearity (R(2)=0.9999) for kanamycin. It shows a good precision expressed as RSD on the relative peak areas equal to 0.3 and 1.1% for intra-day and inter-day precision, respectively. The LOD and LOQ are 0.7 and 2.3 mg/L, respectively. Similarly, for sulphate, a good linearity (R(2)=0.9996) and precision (RSD 0.4 and 0.6% for intra-day and inter-day, respectively) were obtained.

  2. Determination of γ-hydroxybutyric acid in saliva by capillary electrophoresis coupled with contactless conductivity and indirect UV absorbance detectors.

    PubMed

    Mazina, Jekaterina; Saar-Reismaa, Piret; Kulp, Maria; Kaljurand, Mihkel; Vaher, Merike

    2015-12-01

    The aim of the current study was to optimise and validate the methodology for determination of γ-hydroxybutyric acid (GHB) in saliva by CE combined with a contactless conductivity detector (C(4)D) and indirect UV absorbance detection (λ(ABS) = 210 nm). The optimized BGE, consisting of 8.5 mM maleic acid, 17 mM arginine, 255 μM cetyltrimethylammonium bromide (CTAB), and 15% acetonitrile, was evaluated for the separation of GHB in saliva within 6 min. The performance characteristics of the CE-C(4)D-indirect UV methodology was validated. The instrument detection and quantification limits were 0.49 and 1.6 mg/L for C(4)D, and 5.1 mg/L and 17.0 mg/L for indirect UV, respectively. The linearity was obtained over the range from 2.5 to 400 mg/L for C(4)D and from 12.5 to 400 mg/L for indirect UV. The interday precisions were within 2.3-5.7% and intraday precisions were within 1.6-9.0% for C(4)D as well as 2.1-9.3%, 5.6-10.1% for indirect UV in spiked saliva, respectively. The recoveries were within 87.2-104.4%. The matrix effects were +53.2% for small concentrations up to 25 mg/L for C(4)D and +23.6% for concentrations up to 75 for mg/L for indirect UV detection. No matrix effects were observed for higher concentration levels. In conclusion, CE-C4D-indirect UV can offer a rapid, accurate, sensitive, and definitive method for the determination of GHB abuse in saliva samples as a forensic screening tool. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Portable integrated capillary-electrophoresis system using disposable polymer chips with capacitively coupled contactless conductivity detection for on-site analysis of foodstuff

    NASA Astrophysics Data System (ADS)

    Gärtner, Claudia; Hoffmann, Werner; Demattio, Horst; Clemens, Thomas; Klotz, Matthias; Klemm, Richard; Becker, Holger

    2009-05-01

    We present a compact portable chip-based capillary electrophoresis system that employs capacitively coupled contactless conductivity detection (C4D) operating at 4 MHz as an alternative detection method compared to the commonly used optical detection based on laser-induced fluorescence. Emphasis was put on system integration and industrial manufacturing technologies for the system. Therefore, the disposable chip for this system is fabricated out of PMMA using injection molding; the electrodes are screen-printed or thin-film electrodes. The system is designed for the measurement of small ionic species like Li+, Na+, K+, SO42- or NO3- typically present in foods like milk and mineral water as well as acids e.g. in wine.

  4. Ultra-fast determination of caffeine, dipyrone, and acetylsalicylic acid by capillary electrophoresis with capacitively coupled contactless conductivity detection and identification of degradation products.

    PubMed

    Marra, Mariana Cardoso; Cunha, Rafael Rodrigues; Vidal, Denis Tadeu Rajh; Munoz, Rodrigo Alejandro Abarza; do Lago, Claudimir Lucio; Richter, Eduardo Mathias

    2014-01-31

    Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) was used for fast, simultaneous determination of dipyrone (DIP), caffeine (CAF), and acetylsalicylic acid (ASA). In the same run and in less than 1min, the degradation products from DIP and ASA were also detected. In addition, the usage of the CE-C(4)D system allowed, for the first time, the detection of methylamine as a degradation product of DIP. Capillary electrophoresis with electrospray mass spectrometry experiments were carried out in order to confirm the formation of methylamine. The limits of detection by CE-C(4)D were 5, 5, and 6μmolL(-1) for CAF, DIP, and ASA, respectively. The proposed method was applied to the analysis of these compounds in pharmaceutical formulations with similar results to those achieved by HPLC (p<0.05).

  5. A low-cost method for determination of calcium carbonate in cement by membraneless vaporization with capacitively coupled contactless conductivity detection.

    PubMed

    Sereenonchai, Kamonthip; Teerasong, Saowapak; Chan-Eam, Sumonmarn; Saetear, Phoonthawee; Choengchan, Nathawut; Uraisin, Kanchana; Amornthammarong, Natchanon; Motomizu, Shoji; Nacapricha, Duangjai

    2010-05-15

    This work presents a flow analysis method for direct quantitation of calcium carbonate in cement without pretreatment of the sample. The method is based on online vaporization of CO(2) gas following acidification of the sample inside a small chamber that has a flow of acceptor solution passing around it. Solubilization of the CO(2) gas into the acceptor stream changes the conductivity of the acceptor solution causing an increase of signal at the capacitively coupled contactless conductivity detection (C(4)D) placed at the outlet of the vaporization chamber. This chamber is an adaption from previous work reported on 'membraneless vaporization' (MBL-VP). The method can be used in the quality control of production of mixed cement. These cement materials usually have calcium carbonate contents at high concentration range (e.g., 33-99% (w/w) CaCO(3)). Analysis of samples by this method is direct and convenient as it requires no sample pretreatment. The method is low-cost with satisfactory accuracy and acceptable precision.

  6. A simple method for determination of erythritol, maltitol, xylitol, and sorbitol in sugar-free chocolates by capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Coelho, Aline Guadalupe; de Jesus, Dosil Pereira

    2016-11-01

    In this work, a novel and simple analytical method using capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4) D) is proposed for the determination of the polyols erythritol, maltitol, xylitol, and sorbitol in sugar-free chocolate. CE separation of the polyols was achieved in less than 6 min, and it was mediated by the interaction between the polyols and the borate ions in the background electrolyte, forming negatively charged borate esters. The extraction of the polyols from the samples was simply obtained using ultra-pure water and ultrasonic energy. Linearity was assessed by calibration curves that showed R(2) varying from 0.9920 to 0.9976. The LOQs were 12.4, 15.9, 9.0, and 9.0 μg/g for erythritol, maltitol, xylitol, and sorbitol, respectively. The accuracy of the method was evaluated by recovery tests, and the obtained recoveries varied from 70 to 116% with standard deviations ranging from 0.2 to 19%. The CE-C(4) D method was successfully applied for the determination of the studied polyols in commercial samples of sugar-free chocolate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Development and validation of a capillary electrophoresis method with capacitively coupled contactless conductivity detection (CE-C(4) D) for the analysis of amikacin and its related substances.

    PubMed

    El-Attug, Mohamed Nouri; Adams, Erwin; Van Schepdael, Ann

    2012-09-01

    Amikacin is a semisynthetic aminoglycoside antibiotic derived from kanamycin A that lacks a strong UV absorbing chromophore or fluorophore. Due to the physicochemical properties of amikacin and its related substances, CE in combination with capacitively coupled contactless conductivity detection (CE-C(4) D) was chosen. The optimized separation method uses a BGE composed of 20 mM MES adjusted to pH 6.6 by l-histidine and 0.3 mM CTAB that was added as flow modifier in a concentration below the CMC. Ammonium acetate 20 mg.L(-1) was used as internal standard. 30 kV was applied in reverse polarity on a fused silica capillary (73/48 cm; 75 μm id). The optimized separation was obtained in less than 6 min with good linearity (R(2) = 0.9996) for amikacin base. It shows a good precision expressed as RSD on relative peak areas equal to 0.1 and 0.7% for intraday and interday, respectively. The LOD and LOQ are 0.5 mg.L(-1) and 1.7 mg.L(-1) , respectively.

  8. Determination of vitamin C and preservatives in beverages by conventional capillary electrophoresis and microchip electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Law, Wai Siang; Kubán, Pavel; Zhao, Jian Hong; Li, Sam Fong Yau; Hauser, Peter C

    2005-12-01

    The separation and detection of commonly used preservatives (benzoate, sorbate) and vitamin C by both conventional CE and microchip electrophoresis with capacitively coupled contactless conductivity detection is presented. The separation was optimized by adjusting the pH-value of the buffer and the use of hydroxypropyl-beta-CD (HP-beta-CD) and CTAB as additives. For conventional CE, optimal separation conditions were achieved in a histidine/tartrate buffer at pH 6.5, containing 0.025% HP-beta-CD and 0.1 mM CTAB. LOD ranged from 0.5 to 3 mg/L (S/N = 3) and the RSDs for migration time and peak area were less than 0.1 and 2%, respectively. A considerable reduction of analysis time can be accomplished by using microchip electrophoresis without significant loss in sensitivity under optimal separation conditions. A histidine/tartrate buffer at pH 6.5, incorporating 0.06% HP-beta-CD and 0.25 mM CTAB, gave detection limits ranging between 3 and 10 mg/L and satisfactory reproducibilities of < or =0.4% for the migration time and < or =3.5% for the peak area. The methods developed are useful for the quantitative determination of food additives in real samples such as soft drinks and vitamin C tablets.

  9. Characterization of a capacitance-coupled contactless conductivity detection system with sidewall electrodes on a low-voltage-driven electrophoresis microchip.

    PubMed

    Xu, Yi; Liang, Jing; Liu, Haitao; Hu, Xiaoguo; Wen, Zhiyu; Wu, Yongjie; Cao, Mingxia

    2010-06-01

    A new type of capacitance-coupled contactless conductivity detection (C(4)D) system with sidewall electrodes was proposed for integration on a silicon-on-isolator-poly(dimethylsiloxane) (SOI-PDMS) hybrid low-voltage-driven electrophoresis microchip. By a microelectromechanical system process, the sidewall electrodes were fabricated precisely at either side of the separation channel. The area of the capacitor electrodes was the maximum value to improve the detection sensitivity with an enhanced capacitance effect. According to the simulation results, the structural parameters of the sidewall electrodes were determined as 550-microm length, 15-microm width, 80-microm separation distance, and 1-microm isolator thickness. The integrated microdevice with the SOI-PDMS hybrid electrophoresis microchip was very compact and the size was only 15 cm x 15 cm x 10 cm (width x length x height), which permitted miniaturization and portability. The detector performance was evaluated by K(+) testing. The detection limit of the conductivity detector was determined to be 10(-9) and 10(-6) M for K(+) in the static and electric-driven modes, respectively. Finally, the C(4)D was applied to low-voltage-driven electrophoresis on a microchip to carry out real-time measurement of the separation of amino acids. The separations of 10(-4) M lysine and phenylalanine in the low-voltage-driven electrophoresis mode were performed with an electric field of 300 V/cm and were completed in less than 15 min with a resolution of 1.3. The separation efficiency was found to be 1.3 x 10(3) and 2.8 x 10(3) plates for lysine and phenylalanine, respectively, with a migration time reproducibility of 2.7 and 3.2%. The conductivity detection limit of amino acids achieved was 10(-6) M. The proposed method for the construction of a novel C(4)D integrated on an SOI-PDMS hybrid low-voltage-driven electrophoresis microchip showed the most extensive integration and miniaturization of a microdevice, which is a further

  10. A portable lab-on-a-chip instrument based on MCE with dual top-bottom capacitive coupled contactless conductivity detector in replaceable cell cartridge.

    PubMed

    Ansari, Kambiz; Ying, Jasmine Yuen Shu; Hauser, Peter C; de Rooij, Nico F; Rodriguez, Isabel

    2013-05-01

    A new design for a compact portable lab-on-a-chip instrument based on MCE and dual capacitively coupled contactless conductivity detection (dC(4) D) is described. The instrument is battery powered with total dimension of 14 × 25 × 8 cm(3) (w × l × h), and weighs 1.2 kg. The device consists of a front electrophoresis compartment which has the chip holder and the chip, the associated high-voltage electrodes for electrophoresis injection and separation and the detector. The detection cell is integrated into the device housing with an exchangeable plug-and-play cartridge format. The design of the dC(4) D cell has been optimized for maximum performance. The cartridge includes the top-bottom excitation and pick up electrodes incorporated into the cell and connected to push-pull self-latching pins that are insulated with plastic. The metal frame of the cartridge is grounded completely to eliminate electronic interferences. The cartridge is designed to clamp a thin fluidic chip at the detection point. The cartridges are replaceable whereby different cartridges have different detection electrode configurations to employ according to the sensitivity or resolution needed in the specific analytical application. The second compartment consists of all the electronics, data acquisition card, high-voltage modules of up to ±5 kV both polarity, and batteries for 10 h of operation. The improved detector performance is illustrated by the electrophoresis analysis of six cations (NH4 (+) , K(+) , Ca(2+) , Na(+) , Mg(2+) , Li(+) ) with a detection limit of approximately 5 μM and the analysis of the anions (Br(-) , Cl(-) , NO2 (-) , NO3 (-) , SO4 (2-) , F(-) ) with a detection limit of about 3 μM. Analytical capabilities of the instrument for food and medical applications were evaluated by simultaneous detection of organic and inorganic acids in fruit juice and inorganic cations and anions in rabbit blood samples and human urine samples are also demonstrated. © 2013 WILEY

  11. Microchip electrophoresis in low-temperature co-fired ceramics technology with contactless conductivity measurement.

    PubMed

    Fercher, Georg; Smetana, Walter; Vellekoop, Michiel J

    2009-07-01

    In this paper a novel micromachined contactless conductivity CE device produced in low temperature co-fired ceramics (LTCC) is introduced. The application of LTCC multilayer technology provides a promising method for the contactless detection of conductive compounds because of its increased dielectric constant compared with glass or plastics. The capacitive coupling of the excitation signal into the microchannel across the LTCC substrate is improved, resulting in better detection sensitivity. Two silver electrodes located externally at opposite sides at the end of the separation channel act as detector. Impedance variations in the channel are measured without galvanic contact between electrodes and fluid. Inorganic ions are separated in less than 1 min with this novel ceramic device. The limit of detection is 10 microM for potassium.

  12. Determination of hydrazines by chip electrophoresis with contactless conductivity detection.

    PubMed

    Kumar, Ashwini; Burns, Jacob; Hoffmann, Werner; Demattio, Horst; Malik, Ashok Kumar; Matysik, Frank-Michael

    2011-04-01

    In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1-dimethylhydrazine (UDMH)) were separated within < 30 s at a separation voltage of 3.8 kV using a L(-)-histidine/2-(N-morpholinoethanesulfonic acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound-assisted headspace single-drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real-world applications.

  13. Contactless electrical conductivity measurement of electromagnetically levitated metallic melts

    SciTech Connect

    Richardsen, T.; Lohoefer, G.

    1999-07-01

    The electrical conductivity {sigma} of metallic liquids is of obvious importance to many liquid metal processing operations, because it controls the melt flow under the influence of electromagnetic fields, e.g. during casting processes, or in crystal growth furnaces. A facility for noninvasive measurements of the electrical conductivity of liquid metals above and below the melting temperature is presented. It combines the containerless positioning method of electromagnetic levitation with the contactless technique of inductive conductivity measurement. Contrary to the conventional measurement method, the sample is freely suspended within the measuring field and, thus, has no exactly predefined shape. This made a new theoretical basis necessary with implications on the measurement and levitation fields. Furthermore, the problem of the mutual inductive interactions between the levitation and the measuring coils had to be solved.

  14. Separation of enantiomers in capillary electrophoresis with contactless conductivity detection.

    PubMed

    Gong, Xiao Yang; Kubán, Pavel; Tanyanyiwa, Jatisai; Hauser, Peter C

    2005-08-05

    Contactless conductivity detection is successfully demonstrated for the enantiomeric separation of basic drugs and amino acids in capillary electrophoresis (CE). Derivatization of the compounds or the addition of a visualization agent as for indirect optical detection schemes were not needed. Non-charged chiral selectors were employed, hydroxypropylated cyclodextrin (CD) for the more lipophilic basic drugs and 18-crown-6-tetracarboxylic acid (18C6H4) for the amino acids. Acidic buffer solutions based on lactic or citric acid were used. The detection limits were determined as 0.3 microM for pseudoephedrine as an example of a basic drug and were in the range from 2.5 to 20 microM for the amino acids.

  15. Dual contactless conductivity and amperometric detection on hybrid PDMS/glass electrophoresis microchips.

    PubMed

    Vázquez, Mercedes; Frankenfeld, Celeste; Coltro, Wendell K Tomazelli; Carrilho, Emanuel; Diamond, Dermot; Lunte, Susan M

    2010-01-01

    A new approach for the integration of dual contactless conductivity and amperometric detection with an electrophoresis microchip system is presented. The PDMS layer with the embedded channels was reversibly sealed to a thin glass substrate (400 microm), on top of which a palladium electrode had been previously fabricated enabling end-channel amperometric detection. The thin glass substrate served also as a physical wall between the separation channel and the sensing copper electrodes for contactless conductivity detection. The latter were not integrated in the microfluidic device, but fabricated on an independent plastic substrate allowing a simpler and more cost-effective fabrication of the chip. PDMS/glass chips with merely contactless conductivity detection were first characterized in terms of sensitivity, efficiency and reproducibility. The separation efficiency of this system was found to be similar or slightly superior to other systems reported in the literature. The simultaneous determination of ionic and electroactive species was illustrated by the separation of peroxynitrite degradation products, i.e. NO(3)(-) (non-electroactive) and NO(2)(-) (electroactive), using hybrid PDMS/glass chips with dual contactless conductivity and amperometric detection. While both ions were detected by contactless conductivity detection with good efficiency, NO(2)(-) was also simultaneously detected amperometrically with a significant enhancement in sensitivity compared to contactless conductivity detection.

  16. Operating characteristics of contactless power transfer for electric vehicle from HTS antenna to normal conducting receiver

    NASA Astrophysics Data System (ADS)

    Chung, Yoon Do; Lee, Chang Young; Jo, Hyun Chul; Park, Young Gun; Yim, Seong Woo

    2014-09-01

    As contactless power transfer (CPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUCPT4EV) system. As the HTS coil has an enough current density and high quality factor Q value, it can deliver a mass amount of electric energy and improved efficiency in spite of a small scale antenna. The SUCPT4EV system has been expected as a reasonable option to improve the transfer efficiency of large electric power. In this study, we examined the improvement of transmission efficiency and properties for HTS transmitted antenna coils within 40 cm distance at radio frequency (RF) generator of 60 W, 370 kHz. In addition, we achieved impedance matching conditions for different material coils between HTS and normal conductors.

  17. New contactless eddy current non-destructive methodology for electric conductivity measurement

    NASA Astrophysics Data System (ADS)

    Bouchala, T.; Abdelhadi, B.; Benoudjit, A.

    2015-01-01

    In this paper, a new method of contactless electric conductivity measurement is developed. This method is essentially based on the association of the coupled electric field forward model, which we have recently developed, with a simple and efficient research algorithm. The proposed method is very fast because 1.3 s are sufficient to calculate electric conductivity, in a CPU of 2 GHz and RAM of 3 GB, for a starting research interval of 1.72-17.2 %IACS and tolerance of 1.72 × 10- 5 %IACS. The study of the calculation time according to mesh density and starting interval width has showed that an optimal choice has to be made in order to improve the rapidity while preserving its precision. Considering its rapidity and its simplicity of implementation, this method is more adapted, in comparison to direct current techniques using Van der Pauw geometry, for automated applications.

  18. Quantification of plasma lactate concentrations using capillary electrophoresis with contactless conductivity detection.

    PubMed

    Pormsila, Worapan; Morand, Réjane; Krähenbühl, Stephan; Hauser, Peter C

    2011-04-01

    The quantification of plasma lactate and evaluation of the lactate threshold by CE with capacitively coupled contactless conductivity is demonstrated. The only sample preparation needed was deproteinization with a ACN/methanol mixture. A solution of 10 mmol/L 2-morpholinoethanesulfonic acid monohydrate, 10 mmol/L DL-histidine, 70 μmol/L hexadecyltrimethylammonium bromide, pH 6.0 was found suitable as running buffer. Linearity was achieved for the concentration range of 10-1000 μmol/L with a correlation coefficient of 0.9994. The limit of detection (3 S/N) was determined as 3.2 μmol/L. Intra- and inter-day variabilities were less than 7% RSD. The suitability of the method could be demonstrated by analyzing various clinical samples, where the results correlated satisfactorily with those of an established enzymatic method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Portable CE system with contactless conductivity detection in an injection molded polymer chip for on-site food analysis

    NASA Astrophysics Data System (ADS)

    Becker, Holger; Mühlberger, Holger; Hoffmann, Werner; Clemens, Thomas; Klemm, Richard; Gärtner, Claudia

    2008-02-01

    We present a compact portable chip-based capillary electrophoresis system that employs capacitively coupled contactless conductivity detection (C 4D) operating at 4 MHz as an alternative detection method compared to the commonly used optical detection employing laser-induced fluorescence. The disposable chip for this system is fabricated out of PMMA using injection molding; the electrodes are screen-printed or thin-film electrodes. The system allows the measurement of small ions like Li, Na, K typically present in foodstuff like milk and mineral water as well as acids in wine.

  20. End-to-end differential contactless conductivity sensor for microchip capillary electrophoresis.

    PubMed

    Fercher, Georg; Haller, Anna; Smetana, Walter; Vellekoop, Michael J

    2010-04-15

    In this contribution, a novel measurement approach for miniaturized capillary electrophoresis (CE) devices is presented: End-to-end differential capacitively coupled contactless conductivity measurement. This measurement technique is applied to a miniaturized CE device fabricated in low-temperature cofired ceramics (LTCC) multilayer technology. The working principle is based on the placement of two distinct detector areas near both ends of the fluid inlet and outlet of the separation channel. Both output signals are subtracted from each other, and the resulting differential signal is amplified and measured. This measurement approach has several advantages over established, single-end detectors: The high baseline level resulting from parasitic stray capacitance and buffer conductivity is reduced, leading to better signal-to-noise ratio and hence higher measurement sensitivity. Furthermore, temperature and, thus, baseline drift effects are diminished owing to the differentiating nature of the system. By comparing the peak widths measured with both detectors, valuable information about zone dispersion effects arising during the separation is obtained. Additionally, the novel measurement scheme allows the determination of dispersion effects that occur at the time of sample injection. Optical means of dispersion evaluation are ineffective because of the opaque LTCC substrate. Electrophoretic separation experiments of inorganic ions show sensitivity enhancements by about a factor of 30-60 compared to the single-end measurement scheme.

  1. Investigation of conductive thermal control coatings by a contactless method in vacuo

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Shai, C. M.; Sanford, E. L.

    1977-01-01

    A technique for determining the conductance per unit area of thermal control coatings for electrostatically clean spacecraft is described. In order to simulate orbital conditions more closely, current-density-voltage (j-V) curves are obtained by a contactless method in which the paint on an aluminum substrate is the anode of a vacuum diode configuration with a tungsten filament cathode. Conductances per unit area which satisfy the International Sun Earth Explorer (ISEE) requirement were observed on black paints containing carbon and in white and green paints filled with zinc oxide which were fired in order to induce defect conductivity. Because of surface effects and the nonhomogeneous nature of paints, large discrepancies were found between measurements with the contactless method and measurements employing metallic contacts, particularly at low current densities. Therefore, measurements with metallic contacts are considered to be of questionable value in deciding the suitability of coatings for electrostatic charge control.

  2. Determination of glyphosate and AMPA on polyester-toner electrophoresis microchip with contactless conductivity detection.

    PubMed

    da Silva, Eduardo R; Segato, Thiago P; Coltro, Wendell K T; Lima, Renato S; Carrilho, Emanuel; Mazo, Luiz H

    2013-07-01

    This paper reports a method for rapid, simple, direct, and reproducible determination of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA). The platform described herein uses polyester-toner microchips incorporating capacitively coupled contactless conductivity detection and electrophoresis separation of the analytes. The polyester-toner microchip presented 150 μm-wide and 12 μm-deep microchannels, with injection and separation lengths of 10 and 40 mm long, respectively. The best results were obtained with 320 kHz frequency, 4.5 Vpp excitation voltage, 80 mmol/L CHES/Tris buffer at pH 8.8, injection in -1.0 kV for 7 s, and separation in -1.5 kV. RSD values related to the peak areas for glyphosate and AMPA were 1.5 and 3.3% and 10.1 and 8.6% for intra- and interchip assays, respectively. The detection limits were 45.1 and 70.5 μmol/L, respectively, without any attempt of preconcentration of the analytes. Finally, the method was applied to river water samples in which glyphosate and AMPA (1.0 mmol/L each) were added. The recovery results were 87.4 and 83.7% for glyphosate and AMPA, respectively. The recovery percentages and LOD values obtained here were similar to others reported in the literature.

  3. Capillary electrophoresis with contactless conductivity detection for uric acid determination in biological fluids.

    PubMed

    Pormsila, Worapan; Krähenbühl, Stephan; Hauser, Peter C

    2009-03-23

    The suitability of capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4)D) for the direct determination of uric acid in human plasma and urine was investigated. It was found that a careful optimization of the buffer composition and pH was necessary to achieve selective determination in the complex sample matrices. An electrolyte solution consisting of 10mM 2-morpholinoethanesulfonic acid (MES), 10mM histidine and 0.1mM hexadecyltrimethylammonium bromide (CTAB), pH 6.0, was finally found suitable for use as running buffer for both sample matrices. The limit of detection (3 S/N) was determined as 3.3 microM. The linearity of the response was tested for the range between 10 and 500 microM and a correlation coefficient of 0.9996 was obtained. Intra- and inter-day variabilities were <10%. Quantitative analysis of urine and plasma samples showed a good correlation with the routine enzymatic method currently used at the University Hospital of Basel.

  4. Direct determination of valproic acid in biological fluids by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Belin, Gamze Kavran; Krähenbühl, Stephan; Hauser, Peter C

    2007-03-01

    Capacitively coupled contactless conductivity detection (C(4)D) is a new technique providing high sensitivity in capillary electrophoresis (CE) especially for small ions that can otherwise only be determined with indirect methods. In this work, direct determination and validation of valproic acid (VPA) in biological fluids was achieved using CE with C(4)D. VPA is of pharmacological interest because of its use in epilepsy and bipolar disorder. The running electrolyte solution used consisted of 10mM 2-(N-morpholino)ethane sulfonic acid (MES)/dl-histidine (His) and 50microM hexadecyltrimethylammonium bromide (HTAB) at pH 6.0. Caproic acid (CA) was selected as internal standard (IS). Analyses of VPA in serum, plasma and urine samples were performed in less than 3min. The interference of the sample matrix was reduced by deproteinization of the sample with acetonitrile (ACN). The effect of the solvent type and ratio on interference was investigated. The limits of detection (LOD) and quantitation (LOQ) of VPA in plasma samples were determined as 24 and 80ng/ml, respectively. The method is linear between the 2 and 150microg/ml, covering well the therapeutic range of VPA (50-100microg/ml).

  5. Fabrication and characterization of semicircular detection electrodes for contactless conductivity detector - CE microchips.

    PubMed

    Lee, Chia-Yen; Chen, C M; Chang, Guan-Liang; Lin, Che-Hsin; Fu, Lung-Ming

    2006-12-01

    This study uses simple and reliable microfabrication techniques to fabricate CE biochips, integrating a novel contactless conductivity detector in a miniaturized detection system in a microfluidic biochip. The off-channel electrodes are deposited around side channels by Au sputtering and patterned using a standard "lift-off" process. A vacuum fusion bonding process is employed to seal the lower substrate containing the microchannels and the electrodes to an upper glass cover plate. The variations in the capacitance between the semicircular detection electrodes in the side channels are measured as different samples and ions pass through the detection region of the CE separation channel. Samples of Rhodamine B, commercial sports drinks, mineral waters, and a red wine, respectively, are mixed in different buffer solutions, separated, and successfully detected using the developed device. The semicircular detection electrodes for the contactless conductivity detector have microscale dimensions and provide a valuable contribution to the realization of the lab-on-a-chip concept.

  6. Implementation of a Data Acquisition System for Contactless Conductivity Imaging

    DTIC Science & Technology

    2007-11-02

    are connected in series to cancel out the voltage induced by direct coupling. The time varying magnetic field in the transmitter coil induces...caused by the induced currents. The electromotive force in the receiver coil can be expressed as: ∇+⋅−⋅−= −= ’)()())(( dVAw I Aw ld I Aw Ijv jwv T

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

    SciTech Connect

    Drichko, I. L.; Diakonov, A. M.; Malysh, V. A.; Smirnov, I. Yu.; Ilyinskaya, N. D.; Usikova, A. A.; Galperin, Y. M.; Kummer, M.; Känel, H. von

    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.

  8. Three-phase inductive-coupled structures for contactless PHEV charging system

    NASA Astrophysics Data System (ADS)

    Lee, Jia-You; Shen, Hung-Yu; Li, Cheng-Bin

    2016-07-01

    In this article, a new-type three-phase inductive-coupled structure is proposed for the contactless plug-in hybrid electric vehicle (PHEV) charging system regarding with SAE J-1773. Four possible three-phase core structures are presented and subsequently investigated by the finite element analysis. To study the correlation between the core geometric parameter and the coupling coefficient, the magnetic equivalent circuit model of each structure is also established. In accordance with the simulation results, the low reluctance and the sharing of flux path in the core material are achieved by the proposed inductive-coupled structure with an arc-shape and three-phase symmetrical core material. It results in a compensation of the magnetic flux between each phase and a continuous flow of the output power in the inductive-coupled structure. Higher coupling coefficient between inductive-coupled structures is achieved. A comparison of coupling coefficient, mutual inductance, and self-inductance between theoretical and measured results is also performed to verify the proposed model. A 1 kW laboratory scale prototype of the contactless PHEV charging system with the proposed arc-shape three-phase inductive-coupled structure is implemented and tested. An overall system efficiency of 88% is measured when two series lithium iron phosphate battery packs of 25.6 V/8.4 Ah are charged.

  9. Enantiomeric separation of some common controlled stimulants by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Mantim, Thitirat; Nacapricha, Duangjai; Wilairat, Prapin; Hauser, Peter C

    2012-01-01

    CE methods with capacitively coupled contactless conductivity detection (C(4)D) were developed for the enantiomeric separation of the following stimulants: amphetamine (AP), methamphetamine (MA), ephedrine (EP), pseudoephedrine (PE), norephedrine (NE) and norpseudoephedrine (NPE). Acetic acid (pH 2.5 and 2.8) was found to be the optimal background electrolyte for the CE-C(4)D system. The chiral selectors, carboxymethyl-β-cyclodextrin (CMBCD), heptakis(2,6-di-O-methyl)-β-cyclodextrin (DMBCD) and chiral crown ether (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18C6H(4)), were investigated for their enantioseparation properties in the BGE. The use of either a single or a combination of two chiral selectors was chosen to obtain optimal condition of enantiomeric selectivity. Enantiomeric separation of AP and MA was achieved using the single chiral selector CMBCD and (hydroxypropyl)methyl cellulose (HPMC) as the modifier. A combination of the two chiral selectors, CMBCD and DMBCD and HPMC as the modifier, was required for enantiomeric separation of EP and PE. In addition, a combination of DMBCD and 18C6H(4) was successfully applied for the enantiomeric separation of NE and NPE. The detection limits of the enantiomers were found to be in the range of 2.3-5.7 μmol/L. Good precisions of migration time and peak area were obtained. The developed CE-C(4)D method was successfully applied to urine samples of athletes for the identification of enantiomers of the detected stimulants.

  10. Electromembrane extraction of diamine plastic restricted substances in soft drinks followed by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Liu, Yan; Guo, Lin; Wang, Yu; Huang, Fengying; Shi, Jing; Gao, Ge; Wang, Xiaoxin; Ye, Jiannong; Chu, Qingcui

    2017-04-15

    Ethane-1,2-diamine (EA) and hexane-1,6-diamine (HA) are two important plastic restricted substances commonly existing in food contact materials. A capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) method has been developed for direct determination of above analytes, and the detection sensitivity has been significantly improved based on electromembrane extraction (EME). Under the optimum conditions, EA and HA could be well separated from their aliphatic diamine homologs as well as the common inorganic cations within 25min. The limits of detection could reach sub-ng/mL level, and good linearity (r>0.998) between peak area and analyte concentration could be obtained at three orders of magnitude. This EME/CE-C(4)D method provided a novel application for determining these plastic restricted substances in different bottled soft drinks, providing an alternative for the sensitive analyses of diamine substances.

  11. Hand-held analyser based on microchip electrophoresis with contactless conductivity detection for measurement of chemical warfare agent degradation products

    NASA Astrophysics Data System (ADS)

    Duran, Karolina-Petkovic; Zhu, Yonggang; Chen, Chuanpin; Swallow, Anthony; Stewart, Robert; Hoobin, Pam; Leech, Patrick; Ovenden, Simon

    2008-12-01

    This paper reports on the development of a hand-held device for on-site detection of organophosphonate nerve agent degradation products. This field-deployable analyzer relies on efficient microchip electrophoresis separation of alkyl methylphosphonic acids and their sensitive contactless conductivity detection. Miniaturized, low-powered design is coupled with promising analytical performance for separating the breakdown products of chemical warfare agents such as Soman, Sarin and VX . The detector has a detection limit of about 10 μg/mL and has a good linear response in the range 10-300 μg/mL concentration range. Applicability to environmental samples is demonstrated .The new hand-held analyzer offers great promise for converting conventional ion chromatography or capillary electrophoresis sophisticated systems into a portable forensic laboratory for faster, simpler and more reliable on-site screening.

  12. Nonaqueous CE using contactless conductivity detection and ionic liquids as BGEs in ACN.

    PubMed

    Borissova, Maria; Gorbatsova, Jelena; Ebber, Arkadi; Kaljurand, Mihkel; Koel, Mihkel; Vaher, Merike

    2007-10-01

    N,N'-Alkylmethylimidazolium cations have been separated in NACE when one of the N,N'-dialkylimidazolium salts (ionic liquids (ILs)) was used as an electrolyte additive to the organic solvent separation medium. The separated species were 1-methyl-, 1-ethyl-, 1-butyl-, 1-octyl-, 1-decyl-3-methylimidazolium and N-butyl-3-methylpyridinium cations and BGE composed of 1-ethyl-3-methylimidazolium ethylsulfate or 1-butyl-3-methylimidazolium trifluoroacetate [BMIm][FAcO] (A6; B2) diluted in ACN. It was demonstrated that contactless conductivity detection (CCD) may be applied to monitoring the separation process in nonaqueous separation media, allowing to use the UV light-absorbing imidazolium-based electrolyte additives. There could be marked three concentration regions of added ILs; at first ionic strength of BGE below 1-2 mM, and then the actual electrophoretic mobility of analytes rises from 0. At concentrations above 1-2 mM, the added IL facilitated separation. In concentration region of 1-20 mM, the actual electrophoretic mobility of analyzed imidazolium cations was increasing with decrease in separation medium ionic strength. At higher concentrations of BGE (above 30 mM), the conductivity of the separation media became too high for this detector. Some organic dyes were also successfully separated and detected by contactless conductivity detector in a 20 mM A6 separation electrolyte in ACN.

  13. Conceptual design of contactless power transfer into HTS receiver coil using normal conducting resonance antenna

    NASA Astrophysics Data System (ADS)

    Kang, Hyoung Ku; Chung, Yoon Do; Yim, Seong Woo

    2014-09-01

    The contactless power transfer (CPT) technology based on strongly coupled electromagnetic resonators has been recently explored to realize the large power delivery and storage without any cable or wire across a large air gap. As the CPT technology makes possible the process of connector-free charging, it has been studied for practical applications to a variety of power applications. In the superconducting magnet system, a widespread method of electric energy supply is realized by the current lead which is one of indispensable subsystems in the power transfer equipment; however, it causes energy losses. To overcome such a problem, the combination CPT technology with HTS receiver coils has been proposed. It is called as, superconducting contactless power transfer (SUCPT) system. Such a technique has been expected a reasonable approach to provide a safe and convenient way of charging or storage without connecting joints in the superconducting applications. In this study, we presented the feasibility and various effects of transmission property from room temperature to very low temperature vessel within 40 cm under different material’s cooling vessels using radio frequency (RF) generator is 370 KHz.

  14. Fabrication of a glass-implemented microcapillary electrophoresis device with integrated contactless conductivity detection.

    PubMed

    Berthold, Axel; Laugere, Frederic; Schellevis, Hugo; de Boer, Charles R; Laros, Mario; Guijt, Rosanne M; Sarro, Pasqualina M; Vellekoop, Michiel J

    2002-10-01

    Glass microdevices for capillary electrophoresis (CE) gained a lot of interest in the development of micrototal analysis systems (microTAS). The fabrication of a microTAS requires integration of sampling, chemical separation and detection systems into a microdevice. The integration of a detection system into a microchannel, however, is hampered by the lack of suitable microfabrication technology. Here, a microfabrication method for integration of insulated microelectrodes inside a leakage-free microchannel in glass is presented. A combination of newly developed technological approaches, such as low-temperature glass-to-glass anodic bonding, channel etching, fabrication of buried metal interconnects, and deposition of thin plasma-enhanced chemical vapour deposition (PECVD) silicon carbide layers, enables the fabrication of a CE microdevice with an integrated contactless conductivity detector. The fabrication method of this CE microdevice with integrated contactless conductivity detector is described in detail. Standard CE separations of three inorganic cations in concentrations down to 5 microM show the viability of the new microCE system.

  15. Contactless Monitoring of Conductivity Changes in Vanadium Pentoxide Xerogel Layers Using Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Rimeika, Romualdas; Sereika, Raimundas; Čiplys, Daumantas; Bondarenka, Vladimiras; Sereika, Albertas; Shur, Michael

    The hydrated form of the vanadium pentoxide (V2O5 ·nH2O) deposited by the sol-gel method on the piezoelectric YZ-LiNbO3 substrate has been studied using surface acoustic waves (SAWs). Brush-deposited and spin-coated layers, differing in thickness by an order of magnitude (∼1 μm and ∼0.1 μm, respectively) were studied. The variations with time in the transmitted SAW amplitude and phase during the gel-to-xerogel transition of V2O5 ·nH2O were observed and attributed to the acoustoelectric interaction. The possibilities of using the SAWs for contactless monitoring of the layer sheet conductivity have been demonstrated.

  16. Fingerprinting postblast explosive residues by portable capillary electrophoresis with contactless conductivity detection.

    PubMed

    Kobrin, Eeva-Gerda; Lees, Heidi; Fomitšenko, Maria; Kubáň, Petr; Kaljurand, Mihkel

    2014-04-01

    A portable capillary electrophoretic system with contactless conductivity detection was used for fingerprint analysis of postblast explosive residues from commercial organic and improvised inorganic explosives on various surfaces (sand, concrete, metal witness plates). Simple extraction methods were developed for each of the surfaces for subsequent simultaneous capillary electrophoretic analysis of anions and cations. Dual-opposite end injection principle was used for fast (<4 min) separation of 10 common anions and cations from postblast residues using an optimized separation electrolyte composed of 20 mM MES, 20 mM l-histidine, 30 μM CTAB and 2 mM 18-crown-6. The concentrations of all ions obtained from the electropherograms were subjected to principal component analysis to classify the tested explosives on all tested surfaces, resulting in distinct cluster formations that could be used to verify (each) type of the explosive. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Measurements of chemical warfare agent degradation products using an electrophoresis microchip with contactless conductivity detector.

    PubMed

    Wang, Joseph; Pumera, Martin; Collins, Greg E; Mulchandani, Ashok

    2002-12-01

    This paper reports on a microfluidic device for the screening of organophosphonate nerve agent degradation products. The miniaturized system relies on an efficient chip-based separation of alkyl methylphosphonic acids (breakdown products of Sarin, Soman, and VX nerve agents) followed by their sensitive contactless conductivity detection. Experimental parameters relevant to the separation and detection processes have been optimized to yield high sensitivity (with 48-86 microg L(-1) detection limits), fast response (50 s for a three alkyl methylphosphonic acid mixture), high precision (RSD = 3.8-5.0%), and good linearity (over the 0.3-100 mg L(-1) range). Applicability to natural (river) water samples is demonstrated. The new microsystem offers promise for monitoring degradation products of chemical warfare agents, with advantages of speed/warning, efficiency, portability, sample size, and cost compared to conventional ion chromatography or capillary electrophoresis systems.

  18. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  19. Sensitive simultaneous determination of three sulfanilamide artificial sweeters by capillary electrophoresis with on-line preconcentration and contactless conductivity detection.

    PubMed

    Yang, Lirong; Zhou, ShengJi; Xiao, Yuezhou; Tang, Yufeng; Xie, Tianyao

    2015-12-01

    A sensitive method followed by capillary electrophoresis with on-line perconcentration and capacitively coupled contactless conductivity detection (CE-C(4)D) was evaluated as a novel approach for the determination of three sulfanilamide artificial sweeteners (acesulfame-K, sodium saccharin and sodium cyclamate) in beverages. The on-line preconcentration technique, namely field-amplified sample injection, coupled with CE-C(4)D were successfully developed and optimized. The separation was achieved within 10 min under the following conditions: an uncoated fused-silica capillary (45 cm × 50 μm i.d., Leff=40 cm), 20 mmol L(-1) HAc as running buffer, separation voltage of -12 kV, electrokinetic injection of -11 kV × 8 s. The detection limits of acesulfame-K, sodium saccharin and sodium cyclamate were 4.4, 6.7 and 8.8 μg L(-1), respectively. The relative standard deviation varied in the range of 3.0-5.0%. Results of this study show a great potential method for the fast screening of these artificial sweeteners contents in commercial beverages. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Rapid and direct determination of glyphosate, glufosinate, and aminophosphonic acid by online preconcentration CE with contactless conductivity detection.

    PubMed

    See, Hong Heng; Hauser, Peter C; Ibrahim, Wan Aini Wan; Sanagi, Mohd Marsin

    2010-01-01

    Rapid and direct online preconcentration followed by CE with capacitively coupled contactless conductivity detection (CE-C(4)D) is evaluated as a new approach for the determination of glyphosate, glufosinate (GLUF), and aminophosphonic acid (AMPA) in drinking water. Two online preconcentration techniques, namely large volume sample stacking without polarity switching and field-enhanced sample injection, coupled with CE-C(4)D were successfully developed and optimized. Under optimized conditions, LODs in the range of 0.01-0.1 microM (1.7-11.1 microg/L) and sensitivity enhancements of 48- to 53-fold were achieved with the large volume sample stacking-CE-C(4)D method. By performing the field-enhanced sample injection-CE-C(4)D procedure, excellent LODs down to 0.0005-0.02 microM (0.1-2.2 microg/L) as well as sensitivity enhancements of up to 245- to 1002-fold were obtained. Both techniques showed satisfactory reproducibility with RSDs of peak height of better than 10%. The newly established approaches were successfully applied to the analysis of glyphosate, glufosinate, and aminophosphonic acid in spiked tap drinking water.

  1. Monitoring of vancomycin in human plasma via portable microchip electrophoresis with contactless conductivity detector and multi-stacking strategy.

    PubMed

    Chong, Kah Chun; Thang, Lee Yien; Quirino, Joselito P; See, Hong Heng

    2017-02-17

    A portable microchip electrophoresis (MCE) coupled with on-chip contactless conductivity detection (C(4)D) system was evaluated for the determination of vancomycin in human plasma. In order to enhance the detection sensitivity, a new online multi-stacking preconcentration technique based on field-enhanced sample injection (FESI) and micelle-to-solvent stacking (MSS) was developed and implemented in MCE-C(4)D system equipped with a commercially available double T-junction glass chip. The cationic analytes from the two sample reservoirs were injected under FESI conditions and subsequently focused by MSS within the sample-loading channel. The proposed multi-stacking strategy was verified under a fluorescence microscope using Rhodamine 6G as the model analyte and a sensitivity enhancement factor (SEF) of up to 217 was achieved. The developed approach was subsequently implemented in the aqueous-based MCE, coupled to C(4)D in order to monitor the targeted antibiotic (in this case, vancomycin) present in human plasma samples. The multi-stacking and analysis time for vancomycin were 50s and 250s respectively, with SEF of approximately 83 when compared to typical gated injection. The detection limit of the method for vancomycin was 1.2μg/mL, with intraday and interday repeatability RSDs of 2.6% and 4.3%, respectively. Recoveries in spiked human plasma were 99.0%-99.2%. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. The use of capillary electrophoresis with contactless conductivity detection for monitoring of glycerol in adipose tissues during a sporting performance.

    PubMed

    Tůma, Petr; Málková, Klára; Wedellová, Zuzana; Samcová, Eva; Stulík, Karel

    2010-06-01

    A CE procedure employing capacitively coupled contactless conductivity detection has been developed for direct determination of the glycerol and mannitol polyalcohols in biological and pharmacological samples. Both glycerol and mannitol are fully separated from the sample matrix within very short times of 3.0 and 3.9 min, respectively, when using the optimized BGE, 60 mM H3BO3+30 mM LiOH (pH 9.1). The LODs amount to 0.5 microM for glycerol and 0.3 microM for mannitol. The repeatability of the glycerol determination in real biological materials is characterized by the coefficient of variation values, 0.5 and 3.2%, for the migration time and the peak area, respectively. The procedure has been used to monitor the free glycerol concentration in adipose tissue microdialyzates. A physiological study has demonstrated that the lipolysis occurring during a sporting action can be stimulated by local application of adrenaline. The procedure has further been utilized to determine mannitol in a pharmacological preparation.

  3. Optimization of capillary electrophoresis method with contactless conductivity detection for the analysis of tobramycin and its related substances.

    PubMed

    El-Attug, Mohamed Nouri; Hoogmartens, Jos; Adams, Erwin; Van Schepdael, Ann

    2012-01-25

    A method was validated and optimized to determine tobramycin (TOB) and its related substances. TOB is an aminoglycoside antibiotic which lacks a strong UV absorbing chromophore or fluorophore. Due to the physicochemical properties of TOB, capillary electrophoresis (CE) in combination with Capacitively Coupled Contactless Conductivity Detection (C(4)D) was chosen. The optimized separation method uses a background electrolyte (BGE) composed of 25 mM morpholinoethane-sulphonic acid (MES) adjusted to pH 6.4 by L-histidine (l-His). 0.3 mM cetyltrimethyl ammonium bromide (CTAB) was added as electroosmotic flow modifier in a concentration below the critical micellar concentration (CMC). Ammonium acetate 50 mg L(-1) was used as internal standard (IS). 30 kV was applied in reverse polarity (cathode at the injection capillary end) on a fused silica capillary (65/43 cm; 75 μm id). The optimized separation was obtained in less than 7 min with good linearity (R(2)=0.9995) for tobramycin. It shows a good precision expressed as RSD on relative peak areas equal to 0.2% and 0.7% for intraday and interday respectively. The LOD and LOQ are 0.4 and 1.3 mg L(-1) corresponding to 9 pg and 31 pg respectively.

  4. Determination of artificial sweeteners by capillary electrophoresis with contactless conductivity detection optimized by hydrodynamic pumping.

    PubMed

    Stojkovic, Marko; Mai, Thanh Duc; Hauser, Peter C

    2013-07-17

    The common sweeteners aspartame, cyclamate, saccharin and acesulfame K were determined by capillary electrophoresis with contactless conductivity detection. In order to obtain the best compromise between separation efficiency and analysis time hydrodynamic pumping was imposed during the electrophoresis run employing a sequential injection manifold based on a syringe pump. Band broadening was avoided by using capillaries of a narrow 10 μm internal diameter. The analyses were carried out in an aqueous running buffer consisting of 150 mM 2-(cyclohexylamino)ethanesulfonic acid and 400 mM tris(hydroxymethyl)aminomethane at pH 9.1 in order to render all analytes in the fully deprotonated anionic form. The use of surface modification to eliminate or reverse the electroosmotic flow was not necessary due to the superimposed bulk flow. The use of hydrodynamic pumping allowed easy optimization, either for fast separations (80s) or low detection limits (6.5 μmol L(-1), 5.0 μmol L(-1), 4.0 μmol L(-1) and 3.8 μmol L(-1) for aspartame, cyclamate, saccharin and acesulfame K respectively, at a separation time of 190 s). The conditions for fast separations not only led to higher limits of detection but also to a narrower dynamic range. However, the settings can be changed readily between separations if needed. The four compounds were determined successfully in food samples.

  5. Portable capillary electrophoresis instrument with automated injector and contactless conductivity detection.

    PubMed

    Mai, Thanh Duc; Pham, Thi Thanh Thuy; Pham, Hung Viet; Sáiz, Jorge; Ruiz, Carmen García; Hauser, Peter C

    2013-02-19

    A portable capillary electrophoresis instrument featuring an automated, robust, valve-based injection system was developed. This significantly facilitates operation in the field compared to previous injection approaches. These generally required delicate manual operations which are difficult to perform outside the laboratory environment. The novel system relies on pressurized air for solution delivery and a micromembrane pump for sample aspiration. Contactless conductivity detection was employed for its versatility and low power requirement. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 × 35 × 15 cm (w × d × h) and a weight of about 8 kg. It can operate continuously for 9 h in the battery-powered mode. Depending on the task at hand, the injection system allows easy optimization for high separation efficiency, for fast separations, or for low limits of detection. To illustrate these features, the separation of four anions within 16 s is demonstrated as well as the determination of nitrite below 1 μM. The determination of phosphate at a sewage treatment plant was carried out to demonstrate a field application.

  6. Application of an external contactless conductivity detector for the analysis of beverages by microchip capillary electrophoresis.

    PubMed

    Kubán, Pavel; Hauser, Peter C

    2005-08-01

    Quantitative total ionic analysis of alcoholic and nonalcoholic beverages was performed by microchip capillary electrophoresis with external contactless conductivity detection. An electrolyte solution consisting of 10.5 mM histidine, 50 mM acetic acid, and 2 mM 18-crown-6 at pH 4.1 was used for the determination of NH(4) (+), K(+), Ca(2+), Na(+), and Mg(2+). Fast analysis of Cl(-), NO(3) (-), and SO(4) (2-) was achieved in 20 mM 2-(N-morpholino)ethanesulfonic acid /histidine electrolyte solution at pH 6.0 and the simultaneous separation of up to 12 inorganic and organic anions was performed in a solution containing 10 mM His and 7 mM glutamic acid at pH 5.75. Limits of detection ranged from 90 to 250 mug/L for inorganic cations and anions, and from 200 to 2000 mug/L for organic anions and phosphate. Calibration curves showed linear dependencies over one to two orders of magnitude when the stacking effect was minimized by injecting standard solutions prepared in background electrolyte solutions. Total analysis times of 35 and 90 s were achieved for the determination of 5 inorganic cations and for the simultaneous determination of 12 inorganic and organic anions, respectively, which represents a considerable reduction of analysis time compared to conventional separation methods used in food analysis.

  7. Using scanning contactless conductivity to optimise photografting procedures and capacity in the production of polymer ion-exchange monoliths.

    PubMed

    Gillespie, Eoin; Connolly, Damian; Paull, Brett

    2009-07-01

    Capacitively coupled contactless conductivity detection (C4D) is utilised as a simple, rapid and non-invasive technique for the quantitative evaluation of the ion-exchange capacity of charged polymer monoliths in capillary format. A charged monomer, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) was photografted onto a 100 microm i.d. butyl methacrylate-co-ethylenedimethacrylate monolith in a number of discrete 10 mm zones. By varying the energy dose (J/cm2) during grafting of each zone, the grafting density and thus ion-exchange capacity could be precisely controlled. Ion-exchange capacity could be correlated with energy dose by measuring the conductive response of each grafted region using scanning C4D techniques. Repeatability of the scanning C4D method was excellent with % RSD values of 0.7% and 2.4% obtained for three replicate scans of the ungrafted and grafted regions of a single monolith, respectively. Repeatability of the photografting process on separate monoliths was also examined by comparison of C4D profiles. The spatial accuracy of photografting was probed using scanning C4D which could measure the conductive response of the monolith at measurement intervals as low as 1 mm along its entire length. Scanning C4D was also used for the real time visualisation of the equilibration of grafted zones to permit the optimisation of monolith washing procedures. Finally, scanning C4D was applied to the measurement of the ion-exchange capacity of butyl methacrylate-co-AMPS-co-ethylenedimethacrylate copolymers with a direct correlation between monolith conductive response and concentration of charged monomer in the polymerisation mixture. The longitudinal homogeneity of charge along the monolith was 0.3% RSD, demonstrating that the charged functional monomer was evenly dispersed throughout the bulk of the monolith. Ion-exchange capacity was cross validated chromatographically using breakthrough studies and found to closely correlate to within 1% of the

  8. Contactless graphene conductivity mapping on a wide range of substrates with terahertz time-domain reflection spectroscopy.

    PubMed

    Lin, Hungyen; Braeuninger-Weimer, Philipp; Kamboj, Varun S; Jessop, David S; Degl'Innocenti, Riccardo; Beere, Harvey E; Ritchie, David A; Zeitler, J Axel; Hofmann, Stephan

    2017-09-06

    We demonstrate how terahertz time-domain spectroscopy (THz-TDS) operating in reflection geometry can be used for quantitative conductivity mapping of large area chemical vapour deposited graphene films on sapphire, silicon dioxide/silicon and germanium. We validate the technique against measurements performed with previously established conventional transmission based THz-TDS and are able to resolve conductivity changes in response to induced back-gate voltages. Compared to the transmission geometry, measurement in reflection mode requires careful alignment and complex analysis, but circumvents the need of a terahertz transparent substrate, potentially enabling fast, contactless, in-line characterisation of graphene films on non-insulating substrates such as germanium.

  9. Simultaneous determination of rare earth elements in ore and anti-corrosion coating samples using a portable capillary electrophoresis instrument with contactless conductivity detection.

    PubMed

    Nguyen, Thi Anh Huong; Nguyen, Van Ri; Le, Duc Dung; Nguyen, Thi Thanh Binh; Cao, Van Hoang; Nguyen, Thi Kim Dung; Sáiz, Jorge; Hauser, Peter C; Mai, Thanh Duc

    2016-07-29

    The employment of an in-house-made capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C(4)D) as a simple and inexpensive solution for simultaneous determination of many rare earth elements (REEs) in ore samples from Vietnam, as well as in anti-corrosion coating samples is reported. 14 REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) were determined using an electrolyte composed of 20mM arginine and 10mM α-hydroxyisobutyric acid adjusted to pH 4.2 with acetic acid. The best detection limit achieved was 0.24mg/L using the developed CE-C(4)D method. Good agreement between results from CE-C(4)D and the confirmation method (ICP-MS) was achieved, with a coefficient of determination (r(2)) for the two pairs of data of 0.998.

  10. Determination of nerve agent degradation products by capillary electrophoresis using field-amplified sample stacking injection with the electroosmotic flow pump and contactless conductivity detection.

    PubMed

    Xu, Li; Hauser, Peter C; Lee, Hian Kee

    2009-07-31

    In the present study, field-amplified sample stacking injection using the electroosmotic flow pump (FAEP) was developed for the capillary electrophoretic separation of the four nerve agent degradation products methylphosphonic acid (MPA), ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA) and cyclohexyl methylphosphonic acid (CMPA). Coupled to contactless conductivity detection, direct quantification of these non-UV active compounds could be achieved. Sensitivity enhancement of up to 500 to 750-fold could be obtained. The newly established approach was applied to the determination of the analytes in river water and aqueous extracts of soil. Detection limits of 0.5, 0.7, 1.4 and 2.7 ng/mL were obtained for MPA, EMPA, IMPA and CMPA, respectively, in river water and 0.09, 0.14, 0.44 and 0.22 microg/g, respectively, in soil.

  11. A novel contactless technique for thermal field mapping and thermal conductivity determination: two-laser Raman thermometry.

    PubMed

    Reparaz, J S; Chavez-Angel, E; Wagner, M R; Graczykowski, B; Gomis-Bresco, J; Alzina, F; Sotomayor Torres, C M

    2014-03-01

    We present a novel contactless technique for thermal conductivity determination and thermal field mapping based on creating a thermal distribution of phonons using a heating laser, while a second laser probes the local temperature through the spectral position of a Raman active mode. The spatial resolution can be as small as 300 nm, whereas its temperature accuracy is ±2 K. We validate this technique investigating the thermal properties of three free-standing single crystalline Si membranes with thickness of 250, 1000, and 2000 nm. We show that for two-dimensional materials such as free-standing membranes or thin films, and for small temperature gradients, the thermal field decays as T(r) ∝ ln(r) in the diffusive limit. The case of large temperature gradients within the membranes leads to an exponential decay of the thermal field, T ∝ exp[ - A·ln(r)]. The results demonstrate the full potential of this new contactless method for quantitative determination of thermal properties. The range of materials to which this method is applicable reaches far beyond the here demonstrated case of Si, as the only requirement is the presence of a Raman active mode.

  12. Contactless electrical conductivity measurement of metallic submicron-grain material: Application to the study of aluminum with severe plastic deformation.

    PubMed

    Mito, M; Matsui, H; Yoshida, T; Anami, T; Tsuruta, K; Deguchi, H; Iwamoto, T; Terada, D; Miyajima, Y; Tsuji, N

    2016-05-01

    We measured the electrical conductivity σ of aluminum specimen consisting of submicron-grains by observing the AC magnetic susceptibility resulting from the eddy current. By using a commercial platform for magnetic measurement, contactless measurement of the relative electrical conductivity σn of a nonmagnetic metal is possible over a wide temperature (T) range. By referring to σ at room temperature, obtained by the four-terminal method, σn(T) was transformed into σ(T). This approach is useful for cylinder specimens, in which the estimation of the radius and/or volume is difficult. An experiment in which aluminum underwent accumulative roll bonding, which is a severe plastic deformation process, validated this method of evaluating σ as a function of the fraction of high-angle grain boundaries.

  13. Capillary electrochromatography with contactless conductivity detection for the determination of some inorganic and organic cations using monolithic octadecylsilica columns.

    PubMed

    Mai, Thanh Duc; Pham, Hung Viet; Hauser, Peter C

    2009-10-27

    A fast separation of alkali and alkaline earth metal cations and ammonium was carried out by capillary electrochromatography on monolithic octadecylsilica columns of 15 cm length and 100 microm inner diameter using water/methanol mixtures containing acetic acid as mobile phase. On-column contactless conductivity detection was used for quantification of these non-UV-absorbing species. The method was also extended successfully to the determination of small amines as well as of amino acids, and the separation selectivity was optimized by varying the composition of the mobile phase. Detection limits of about 1 microM were possible for the inorganic cations as well as for the small amines, while the amino acids could be quantified down to about 10 microM. The separation of 12 amino acids was achieved in the relatively short time of 10 min.

  14. Contactless Determination of Electrical Conductivity of One-Dimensional Nanomaterials by Solution-Based Electro-orientation Spectroscopy

    SciTech Connect

    Akin, Cevat; Yi, Jingang; Feldman, Leonard C.; Durand, Corentin; Hus, Saban M.; Li, An-Ping; Filler, Michael A.; Shan, Jerry W.

    2015-05-05

    For nanowires of the same composition, and even fabricated within the same batch, often exhibit electrical conductivities that can vary by orders of magnitude. Unfortunately, existing electrical characterization methods are time-consuming, making the statistical survey of highly variable samples essentially impractical. Here, we demonstrate a contactless, solution-based method to efficiently measure the electrical conductivity of 1D nanomaterials based on their transient alignment behavior in ac electric fields of different frequencies. In comparison with direct transport measurements by probe-based scanning tunneling microscopy shows that electro-orientation spectroscopy can quantitatively measure nanowire conductivity over a 5-order-of-magnitude range, 10–5–1 Ω–1 m–1 (corresponding to resistivities in the range 102–107 Ω·cm). With this method, we statistically characterize the conductivity of a variety of nanowires and find significant variability in silicon nanowires grown by metal-assisted chemical etching from the same wafer. We also find that the active carrier concentration of n-type silicon nanowires is greatly reduced by surface traps and that surface passivation increases the effective conductivity by an order of magnitude. Moreover, this simple method makes electrical characterization of insulating and semiconducting 1D nanomaterials far more efficient and accessible to more researchers than current approaches. Electro-orientation spectroscopy also has the potential to be integrated with other solution-based methods for the high-throughput sorting and manipulation of 1D nanomaterials for postgrowth device assembly.

  15. Contactless Determination of Electrical Conductivity of One-Dimensional Nanomaterials by Solution-Based Electro-orientation Spectroscopy.

    PubMed

    Akin, Cevat; Yi, Jingang; Feldman, Leonard C; Durand, Corentin; Hus, Saban M; Li, An-Ping; Filler, Michael A; Shan, Jerry W

    2015-05-26

    Nanowires of the same composition, and even fabricated within the same batch, often exhibit electrical conductivities that can vary by orders of magnitude. Unfortunately, existing electrical characterization methods are time-consuming, making the statistical survey of highly variable samples essentially impractical. Here, we demonstrate a contactless, solution-based method to efficiently measure the electrical conductivity of 1D nanomaterials based on their transient alignment behavior in ac electric fields of different frequencies. Comparison with direct transport measurements by probe-based scanning tunneling microscopy shows that electro-orientation spectroscopy can quantitatively measure nanowire conductivity over a 5-order-of-magnitude range, 10(-5)-1 Ω(-1) m(-1) (corresponding to resistivities in the range 10(2)-10(7) Ω·cm). With this method, we statistically characterize the conductivity of a variety of nanowires and find significant variability in silicon nanowires grown by metal-assisted chemical etching from the same wafer. We also find that the active carrier concentration of n-type silicon nanowires is greatly reduced by surface traps and that surface passivation increases the effective conductivity by an order of magnitude. This simple method makes electrical characterization of insulating and semiconducting 1D nanomaterials far more efficient and accessible to more researchers than current approaches. Electro-orientation spectroscopy also has the potential to be integrated with other solution-based methods for the high-throughput sorting and manipulation of 1D nanomaterials for postgrowth device assembly.

  16. Simple semi-automated portable capillary electrophoresis instrument with contactless conductivity detection for the determination of β-agonists in pharmaceutical and pig-feed samples.

    PubMed

    Nguyen, Thi Anh Huong; Pham, Thi Ngoc Mai; Doan, Thi Tuoi; Ta, Thi Thao; Sáiz, Jorge; Nguyen, Thi Quynh Hoa; Hauser, Peter C; Mai, Thanh Duc

    2014-09-19

    An inexpensive, robust and easy to use portable capillary electrophoresis instrument with miniaturized high-voltage capacitively coupled contactless conductivity detection was developed. The system utilizes pneumatic operation to manipulate the solutions for all flushing steps. The different operations, i.e. capillary flushing, interface rinsing, and electrophoretic separation, are easily activated by turning an electronic switch. To allow the analysis of samples with limited available volume, and to render the construction less complicated compared to a computer-controlled counterpart, sample injection is carried out hydrodynamically directly from the sample vial into the capillary by manual syphoning. The system is a well performing solution where the financial means for the highly expensive commercial instruments are not available and where the in-house construction of a sophisticated automated instrument is not possible due to limited mechanical and electronic workshop facilities and software programming expertise. For demonstration, the system was employed successfully for the determination of some β-agonists, namely salbutamol, metoprolol and ractopamine down to 0.7ppm in pharmaceutical and pig-feed sample matrices in Vietnam. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Screening determination of four amphetamine-type drugs in street-grade illegal tablets and urine samples by portable capillary electrophoresis with contactless conductivity detection.

    PubMed

    Nguyen, Thi Anh Huong; Pham, Thi Ngoc Mai; Ta, Thi Thao; Nguyen, Xuan Truong; Nguyen, Thi Lien; Le, Thi Hong Hao; Koenka, Israel Joel; Sáiz, Jorge; Hauser, Peter C; Mai, Thanh Duc

    2015-12-01

    A simple and inexpensive method for the identification of four substituted amphetamines, namely, 3,4-methylenedioxy methamphetamine (MDMA), methamphetamine (MA), 3,4-methylenedioxy amphetamine (MDA) and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) was developed using an in-house constructed semi-automated portable capillary electrophoresis instrument (CE) with capacitively coupled contactless conductivity detection (C(4)D). Arginine 10mM adjusted to pH4.5 with acetic acid was found to be the optimal background electrolyte for the CE-C(4)D determination of these compounds. The best detection limits achieved with and without a sample preconcentration process were 10ppb and 500ppb, respectively. Substituted amphetamines were found in different seized illicit club drug tablets and urine samples collected from different suspected users. Good agreement between results from CE-C(4)D and those with the confirmation method (GC-MS) was achieved, with correlation coefficients for the two pairs of data of more than 0.99.

  18. Electro membrane isolation of nerve agent degradation products across a supported liquid membrane followed by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Xu, Li; Hauser, Peter C; Lee, Hian Kee

    2008-12-19

    In the present study, electro membrane isolation (EMI) of four nerve agent degradation products has been successfully explored. In the procedure, a polypropylene sheet membrane folded into an envelope with an open end with its wall pores impregnated with 1-octanol was employed as the artificial supported liquid membrane (SLM). The envelope containing the extractant or aqueous acceptor phase (at pH 6.8) was immersed in the sample or donor phase (also aqueous at a pH of 6.8) for extraction. This ensured that the target analytes were fully ionized. A voltage was then applied, with the negative electrode placed in the donor phase with agitation, and the positive electrode in the acceptor phase. The ionized analytes were thus driven to migrate from the donor phase across the SLM to the acceptor phase. The factors influential to extraction: type of organic solvent, voltage, agitation speed, extraction time, pH of the donor and acceptor phase and concentration of humic acids were investigated in detail. After extraction, the acceptor phase was collected and directly injected for capillary electrophoretic (CE) analysis. Combined with capacitively coupled contactless conductivity detection (C(4)D), the direct detection of these compounds could be achieved. Moreover, large-volume sample injection was employed to further enhance the sensitivity of this method. Limits of detection (LODs) as low as ng/mL were reached for the studied analytes, with overall LOD enhancements of four orders of magnitude.

  19. Clinical screening of paraquat in plasma samples using capillary electrophoresis with contactless conductivity detection: Towards rapid diagnosis and therapeutic treatment of acute paraquat poisoning in Vietnam.

    PubMed

    Vu, Anh Phuong; Nguyen, Thi Ngan; Do, Thi Trang; Doan, Thu Ha; Ha, Tran Hung; Ta, Thi Thao; Nguyen, Hung Long; Hauser, Peter C; Nguyen, Thi Anh Huong; Mai, Thanh Duc

    2017-08-15

    The employment of a purpose-made capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C(4)D) as a simple and cost-effective solution for clinical screening of paraquat in plasma samples for early-stage diagnosis of acute herbicide poisoning is reported. Paraquat was determined using an electrolyte composed of 10mM histidine adjusted to pH 4 with acetic acid. A detection limit of 0.5mg/L was achieved. Good agreement between results from CE-C(4)D and the confirmation method (HPLC-UV) was obtained, with relative errors for the two pairs of data better than 20% for 31 samples taken from paraquat-intoxicated patients. The results were used by medical doctors for identification and prognosis of acute paraquat poisoning cases. The objective of the work is the deployment of the developed approach in rural areas in Vietnam as a low-cost solution to reduce the mortality rate due to accidental or suicidal ingestion of paraquat. Copyright © 2017. Published by Elsevier B.V.

  20. Contactless Determination of Electrical Conductivity of One-Dimensional Nanomaterials by Solution-Based Electro-orientation Spectroscopy

    DOE PAGES

    Akin, Cevat; Yi, Jingang; Feldman, Leonard C.; ...

    2015-05-05

    For nanowires of the same composition, and even fabricated within the same batch, often exhibit electrical conductivities that can vary by orders of magnitude. Unfortunately, existing electrical characterization methods are time-consuming, making the statistical survey of highly variable samples essentially impractical. Here, we demonstrate a contactless, solution-based method to efficiently measure the electrical conductivity of 1D nanomaterials based on their transient alignment behavior in ac electric fields of different frequencies. In comparison with direct transport measurements by probe-based scanning tunneling microscopy shows that electro-orientation spectroscopy can quantitatively measure nanowire conductivity over a 5-order-of-magnitude range, 10–5–1 Ω–1 m–1 (corresponding to resistivitiesmore » in the range 102–107 Ω·cm). With this method, we statistically characterize the conductivity of a variety of nanowires and find significant variability in silicon nanowires grown by metal-assisted chemical etching from the same wafer. We also find that the active carrier concentration of n-type silicon nanowires is greatly reduced by surface traps and that surface passivation increases the effective conductivity by an order of magnitude. Moreover, this simple method makes electrical characterization of insulating and semiconducting 1D nanomaterials far more efficient and accessible to more researchers than current approaches. Electro-orientation spectroscopy also has the potential to be integrated with other solution-based methods for the high-throughput sorting and manipulation of 1D nanomaterials for postgrowth device assembly.« less

  1. Quantification of terbinafine in pharmaceutical tablets using capillary electrophoresis with contactless conductivity detection and batch injection analysis with amperometric detection.

    PubMed

    Felix, Fabiana S; Ferreira, Luís M C; Rossini, Pamela de O; do Lago, Claudimir L; Angnes, Lúcio

    2012-11-15

    Terbinafine hydrochloride (TerbHCl) is an allylamine derivative with fungicidal action, especially against dermatophytes. Different analytical methods have been reported for quantifying TerbHCl in different samples. These procedures require time-consuming sample preparation or expensive instrumentation. In this paper, electrochemical methods involving capillary electrophoresis with contactless conductivity detection, and amperometry associated with batch injection analysis, are described for the determination of TerbHCl in pharmaceutical products. In the capillary electrophoresis experiments, terbinafine was protonated and analyzed in the cationic form in less than 1 min. A linear range from 1.46 to 36.4 μg mL(-1) in acetate buffer solution and a detection limit of 0.11 μg mL(-1) were achieved. In the amperometric studies, terbinafine was oxidized at +0.85 V with high throughput (225 injection h(-1)) and good linear range (10-100 μmol L(-1)). It was also possible to determine the antifungal agent using simultaneous conductometric and potentiometric titrations in the presence of 5% ethanol. The electrochemical methods were applied to the quantification of TerbHCl in different tablet samples; the results were comparable with values indicated by the manufacturer and those found using titrimetry according to the Pharmacopoeia. The electrochemical methods are simple, rapid and an appropriate alternative for quantifying this drug in real samples.

  2. A simplified poly(dimethylsiloxane) capillary electrophoresis microchip integrated with a low-noise contactless conductivity detector.

    PubMed

    Liu, Benyan; Zhang, Yi; Mayer, Dirk; Krause, Hans-Joachim; Jin, Qinghui; Zhao, Jianlong; Offenhäusser, Andreas

    2011-03-01

    A contactless conductivity detector integrated into a poly(dimethylsiloxane) microchip for electrophoresis is presented. It adopted the simplest configuration of electrodes commonly used in this detection mode for capillary electrophoresis microchips. Although the chip is based on a simple and effective design, it is able to obtain low detection levels due to the low noise of the detection circuit. A circuit based on a lock-in amplifier was designed on printed circuit boards to read out the signal. The property of the detection cell was studied by applying excitation signals of different frequencies and different amplitudes. It was found that the best detection limit could be achieved with a frequency of 50 kHz and amplitude of 20 V. The performance of the detector was demonstrated by successfully separating and detecting several inorganic ions and also a mixture of heavy metal ions. An average detection limit of 0.4 μM was obtained for inorganic cations. This value is significantly improved compared to similar microchip-based detectors. The presented detector could be promising for mass production due to its properties, such as simple construction, high degree of integration, high performance and low cost.

  3. Monitoring the ionic content of exhaled breath condensate in various respiratory diseases by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Greguš, Michal; Foret, František; Kindlová, Dagmar; Pokojová, Eva; Plutinský, Marek; Doubková, Martina; Merta, Zdeněk; Binková, Ilona; Skřičková, Jana; Kubáň, Petr

    2015-05-06

    The analysis of an ionic profile of exhaled breath condensate (EBC) by capillary electrophoresis with contactless conductivity detection and double opposite end injection, is demonstrated. A miniature sampler made from a 2 ml syringe and an aluminium cooling cylinder was used for the fast collection of EBC (under one minute). Analysis of the collected EBC was performed in a 60 mM 2-(N-morpholino)ethanesulfonic acid, 60 mM L-histidine background electrolyte with 30 µM cetyltrimethylammonium bromide and 2 mM 18-crown-6 at pH 6, and excellent repeatability of migration times (RSD  <1.3% (n = 7)) and peak areas (RSD  <  7% (n = 7)) of 14 ions (inorganic anions, cations and organic acids) was obtained. It is demonstrated that the analysis of EBC samples obtained from patients with various respiratory diseases (chronic obstructive pulmonary disease, asthma, pulmonary fibrosis, sarcoidosis, cystic fibrosis) is possible in less than five minutes and the ionic profile can be compared with the group of healthy individuals. The analysis of the ionic profile of EBC samples provides a set of data in which statistically significant differences among the groups of patients could be observed for several clinically relevant anions (nitrite, nitrate, acetate, lactate). The developed collection system and method provides a highly reproducible and fast way of collecting and analyzing EBC, with future applicability in point-of-care diagnostics.

  4. Determination of five priority haloacetic acids by capillary electrophoresis with contactless conductivity detection and solid phase extraction preconcentration.

    PubMed

    Kubáň, Petr; Makarõtševa, Natalja; Kiplagat, Isaac K; Kaljurand, Mihkel

    2012-03-01

    A sensitive capillary electrophoretic separation method with contactless conductivity detection (C4D) for analysis of five priority haloacetic acids (HAA5) is presented. The analytes were baseline separated in an electrolyte composed of 20 mM 2-(N-Morpholino) ethanesulfonic acid (MES), 20 mM L-histidine (HIS), and 30 μM cetyltrimethylammonium bromide (CTAB) at pH 6.0 in less than 4 min. A simplified solid-phase extraction (SPE) preconcentration procedure on highly cross-linked polystyrene-divinylbenzene (PS-DVB) type sorbent was developed and optimized with respect to short preconcentration time. HAA5 from a 25-mL sample aliquot of tap and swimming pool water could be preconcentrated in less than 5 min using an in-house made SPE column with recoveries ranging from 23 to 98%. Combining the SPE preconcentration procedure with capillary electrophoretic analysis, the attained limits of detection were between 6.1 and 12.2 μg/L with total analysis time of less than 10 min.

  5. Environmental formaldehyde analysis by active diffusive sampling with a bundle of polypropylene porous capillaries followed by capillary zone electrophoretic separation and contactless conductivity detection.

    PubMed

    Rocha, Flávio R; Coelho, Lúcia H G; Lopes, Marcelo L A; Carvalho, Lilian R F; da Silva, José A Fracassi; do Lago, Claudimir L; Gutz, Ivano G R

    2008-07-15

    Compared to other volatile carbonylic compounds present in outdoor air, formaldehyde (CH(2)O) is the most toxic, deserving more attention in terms of indoor and outdoor air quality legislation and control. The analytical determination of CH(2)O in air still presents challenges due to the low-level concentration (in the sub-ppb range) and its variation with sampling site and time. Of the many available analytical methods for carbonylic compounds, the most widespread one is the time consuming collection in cartridges impregnated with 2,4-dinitrophenylhydrazine followed by the analysis of the formed hydrazones by HPLC. The present work proposes the use of polypropylene hollow porous capillary fibers to achieve efficient CH(2)O collection. The Oxyphan fiber (designed for blood oxygenation) was chosen for this purpose because it presents good mechanical resistance, high density of very fine pores and high ratio of collection area to volume of the acceptor fluid in the tube, all favorable for the development of air sampling apparatus. The collector device consists of a Teflon pipe inside of which a bundle of polypropylene microporous capillary membranes was introduced. While the acceptor passes at a low flow rate through the capillaries, the sampled air circulates around the fibers, impelled by a low flow membrane pump (of the type used for aquariums ventilation). The coupling of this sampling technique with the selective and quantitative determination of CH(2)O, in the form of hydroxymethanesulfonate (HMS) after derivatization with HSO(3)(-), by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) enabled the development of a complete analytical protocol for the CH(2)O evaluation in air.

  6. Hand drawing of pencil electrodes on paper platforms for contactless conductivity detection of inorganic cations in human tear samples using electrophoresis chips.

    PubMed

    Chagas, Cyro L S; Costa Duarte, Lucas; Lobo-Júnior, Eulício O; Piccin, Evandro; Dossi, Nicolò; Coltro, Wendell K T

    2015-08-01

    This paper describes for the first time the fabrication of pencil drawn electrodes (PDE) on paper platforms for capacitively coupled contactless conductivity detection (C(4) D) on electrophoresis microchips. PDE-C(4) D devices were attached on PMMA electrophoresis chips and used for detection of K(+) and Na(+) in human tear samples. PDE-C(4) D devices were produced on office paper and chromatographic paper platforms and their performance were thoroughly investigated using a model mixture containing K(+) , Na(+) , and Li(+) . In comparison with chromatographic paper, PDE-C(4) D fabricated on office paper has exhibited better performance due to its higher electrical conductivity. Furthermore, the detector response was similar to that recorded with electrodes prepared with copper adhesive tape. The fabrication of PDE-C(4) D on office paper has offered great advantages including extremely low cost (< $ 0.004 per unit), reduced fabrication time (< 5 min), and minimal instrumentation (pencil and paper). The proposed electrodes demonstrated excellent analytical performance with good reproducibility. For an inter-PDE comparison (n = 7), the RSD values for migration time, peak area, and separation efficiency were lower than 2.5, 10.5, and 14%, respectively. The LOD's achieved for K(+) , Na(+) , and Li(+) were 4.9, 6.8, and 9.0 μM, respectively. The clinical feasibility of the proposed approach was successfully demonstrated with the quantitative analysis of K(+) and Na(+) in tear samples. The concentration levels found for K(+) and Na(+) were, respectively, 20.8 ± 0.1 mM and 101.2 ± 0.1 mM for sample #1, and 20.4 ± 0.1 mM and 111.4 ± 0.1 mM for sample #2.

  7. Portable capillary electrophoresis-system for on-site food analysis with lab-on-a-chip based contactless conductivity detection

    NASA Astrophysics Data System (ADS)

    Gärtner, Claudia; Sewart, René; Klemm, Richard; Becker, Holger

    2014-06-01

    A portable analytical system for the characterization of liquid environmental samples and beverages in food control was realized. The key element is the implementation of contactless conductivity detection on lab-on-a-chip basis ensuring the system to be operated in a label free mode. Typical target molecules such as small ionic species like Li+, Na+, K+, SO4 2- or NO3-, organic acids in wine whose concentration and ratio to each other documents the wine quality, or caffeine or phosphate in coke were detected. Results from sample matrices like various beverages as water, cola, tea, wine and milk, water from heaters, environmental samples and blood will be presented.

  8. High-performance liquid chromatography with contactless conductivity detection for the determination of peptides and proteins using a monolithic capillary column.

    PubMed

    Kubán, Pavel; Hauser, Peter C

    2007-12-28

    Gradient programs were applied to the determination of peptides and proteins in HPLC with contactless conductivity detection. A monolithic capillary column was used for the fast and sensitive determination of the biochemical species in acidic mobile phases consisting of acetic acid or trifluoroacetic acid in various concentrations of acetonitrile in water. The drift in baseline, which is caused by conductivity changes during the elution program, was minimized by careful optimization of the composition of the mobile phase and remaining drift was removed by computational baseline normalization. The flow rate from a conventional HPLC pump was reduced to a flow rate suitable for capillary systems using a pre-column flow splitter and a final total flow rate of 1.65 microl/min was used for all capillary HPLC separations. The contactless conductivity detector was positioned directly on the outlet capillary of the separation column and positively charged peptides and proteins were determined as sharp and symmetrical peaks. Detection limits in a concentration range from 3.7 x 10(-8) to 5.1 x 10(-7)M and a reproducibility of peak areas and peak heights between 2.3% and 7.3% were achieved for all biochemical species tested.

  9. Study on the interrelated effects of capillary diameter, background electrolyte concentration, and flow rate in pressure assisted capillary electrophoresis with contactless conductivity detection.

    PubMed

    Mai, Thanh Duc; Hauser, Peter C

    2013-06-01

    A detailed study on the effect of the buffer concentration and the magnitude of the superimposed hydrodynamic flow on separation performance in CZE with contactless conductivity detection was carried out with capillaries of 10, 25, and 50 μm internal diameter. It was confirmed that capillaries of narrow internal diameters require higher buffer concentrations for best sensitivities. For all diameters it was found that electrodispersion was the most pronounced band-broadening factor for relatively long residence times. For shorter times, Joule heating related band broadening appears to be the most significant factor, which means that best separation efficiencies are obtained with the narrowest capillaries. As detection limits are as good for capillaries of 10 μm internal diameters as for the other diameters when using contactless conductivity detection, these narrow capillaries are, therefore, generally of benefit when employing this detection technique. Hydrodyamic flow was found to have only a very limited effect on band broadening; an effect was only noticeable for the 50 μm capillary and relatively high flow rates.

  10. Conduction-coupled Tesla transformer

    NASA Astrophysics Data System (ADS)

    Reed, J. L.

    2015-03-01

    A proof-of-principle Tesla transformer circuit is introduced. The new transformer exhibits the high voltage-high power output signal of shock-excited transformers. The circuit, with specification of proper circuit element values, is capable of obtaining extreme oscillatory voltages. The primary and secondary portions of the circuit communicate solely by conduction. The destructive arcing between the primary and secondary inductors in electromagnetically coupled transformers is ubiquitous. Flashover is eliminated in the new transformer as the high-voltage inductors do not interpenetrate and so do not possess an annular volume of electric field. The inductors are remote from one another. The high voltage secondary inductor is isolated in space, except for a base feed conductor, and obtains earth by its self-capacitance to the surroundings. Governing equations, for the ideal case of no damping, are developed from first principles. Experimental, theoretical, and circuit simulator data are presented for the new transformer. Commercial high-temperature superconductors are discussed as a means to eliminate the counter-intuitive damping due to small primary inductances in both the electromagnetic-coupled and new conduction-coupled transformers.

  11. Conduction-coupled Tesla transformer.

    PubMed

    Reed, J L

    2015-03-01

    A proof-of-principle Tesla transformer circuit is introduced. The new transformer exhibits the high voltage-high power output signal of shock-excited transformers. The circuit, with specification of proper circuit element values, is capable of obtaining extreme oscillatory voltages. The primary and secondary portions of the circuit communicate solely by conduction. The destructive arcing between the primary and secondary inductors in electromagnetically coupled transformers is ubiquitous. Flashover is eliminated in the new transformer as the high-voltage inductors do not interpenetrate and so do not possess an annular volume of electric field. The inductors are remote from one another. The high voltage secondary inductor is isolated in space, except for a base feed conductor, and obtains earth by its self-capacitance to the surroundings. Governing equations, for the ideal case of no damping, are developed from first principles. Experimental, theoretical, and circuit simulator data are presented for the new transformer. Commercial high-temperature superconductors are discussed as a means to eliminate the counter-intuitive damping due to small primary inductances in both the electromagnetic-coupled and new conduction-coupled transformers.

  12. Simultaneous determination of creatinine and acetate by capillary electrophoresis with contactless conductivity detector as a feasible approach for urinary tract infection diagnosis.

    PubMed

    Grochocki, Wojciech; Markuszewski, Michał J; Quirino, Joselito P

    2017-04-15

    Urinary tract infection (UTI) is one of the most common bacterial infection in human but its diagnosis is difficult. Metabolomic studies with nuclear magnetic resonance of urine have shown that acetic acid/creatinine ratio may be used for early UTI diagnosis. Here, a method for simultaneous determination of acetate and creatinine by capillary zone electrophoresis with contactless conductivity detector was developed for the first time. The separation was with 40mM MES and 20mM l-histidine as a background solution. The total time of a single run, including capillary conditioning, was less than 12min. The method was successfully demonstrated for analysis of actual and fortified human urine samples after methanol dilution. Analytical figures of merit such as linearity, LOQ, and repeatability (intraday and interday) were studied.

  13. In situ determination of nerve agents in various matrices by portable capillary electropherograph with contactless conductivity detection.

    PubMed

    Kubáň, Petr; Seiman, Andrus; Makarõtševa, Natalja; Vaher, Merike; Kaljurand, Mihkel

    2011-05-06

    Rapid, efficient and robust methods for sampling and extracting genuine nerve agents sarin, soman and VX were developed for analyzing these compounds on various solid matrices, such as concrete, tile, soil and vegetation. A portable capillary electrophoretic (CE) system with contactless conductometric detection was used for the in situ analysis of the extracted samples. A 7.5 mM MES/HIS-based separation electrolyte accomplished the analysis of target analytes in less than 5 min. The overall duration of the process including instrument start-up, sample extraction and analysis was less than 10 min, which is the fastest screening of nerve agents achieved with liquid phase separation methods to date. The procedure can easily be performed by a person in a protective suit and is therefore suitable for real-life applications. The CE results were validated by an independent GC-MS method and a satisfactory correlation was obtained. The use of a proper sampling strategy with two internal standards and "smart" data-processing software can overcome the low reproducibility of CE. This has a significant impact on the potential acceptance of portable CE instrumentation for the detection and analysis of genuine chemical warfare agents (CWA).

  14. Capillary electrophoresis procedure for the simultaneous analysis and stoichiometry determination of a drug and its counter-ion by using dual-opposite end injection and contactless conductivity detection: application to labetalol hydrochloride.

    PubMed

    Nehmé, Reine; Lascaux, Adrien; Delépée, Raphaël; Claude, Bérengère; Morin, Philippe

    2010-03-24

    In this work, a capillary electrophoresis (CE) procedure was developed for the simultaneous determination of a pharmaceutical drug and its counter-ion, namely labetalol hydrochloride. For this purpose, an uncoated fused-silica capillary, a low conductivity background electrolyte (BGE) and a capacitively coupled contactless conductivity detector (C(4)D) were employed. This detection system is highly sensitive and enables detection of inorganic as well as organic ions unlike with direct UV detection. Moreover, to be able to simultaneously analyze the cationic drug (labetalol(+)) and its anionic counter-ion (Cl(-)) in the same electrophoretic run without the need of a coated capillary, a dual-opposite end injection was performed. In this technique, the sample is hydrodynamically injected into both ends of the capillary. This method is simple and easy to perform since the different injection steps are automated by the CE software. This novel CE-C(4)D procedure with dual-opposite end injection has been successfully validated and applied for the analysis of chloride content in an adrenergic antagonist (labetalol hydrochloride). Thus, the hereby developed method has been shown to enable fast (analysis time<10 min), precise (repeatability of migration times<0.7% and of corrected-peak areas < 3.3%; n=6) and rugged analyses for the simultaneous determination of a pharmaceutical drug and its counter-ion. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Microfluidic mixing using contactless dielectrophoresis.

    PubMed

    Salmanzadeh, Alireza; Shafiee, Hadi; Davalos, Rafael V; Stremler, Mark A

    2011-09-01

    The first experimental evidence of mixing enhancement in a microfluidic system using contactless dielectrophoresis (cDEP) is presented in this work. Pressure-driven flow of deionized water containing 0.5 μm beads was mixed in various chamber geometries by imposing a dielectrophoresis (DEP) force on the beads. In cDEP the electrodes are not in direct contact with the fluid sample but are instead capacitively coupled to the mixing chamber through thin dielectric barriers, which eliminates many of the problems encountered with standard DEP. Four system designs with rectangular and circular mixing chambers were fabricated in PDMS. Mixing tests were conducted for flow rates from 0.005 to 1 mL/h subject to an alternating current signal range of 0-300 V at 100-600 kHz. When the time scales of the bulk fluid motion and the DEP motion were commensurate, rapid mixing was observed. The rectangular mixing chambers were found to be more efficient than the circular chambers. This approach shows potential for mixing low diffusivity biological samples, which is a very challenging problem in laminar flows at small scales.

  16. Determination of the spectrum of low molecular mass organic acids in urine by capillary electrophoresis with contactless conductivity and ultraviolet photometric detection--an efficient tool for monitoring of inborn metabolic disorders.

    PubMed

    Tůma, Petr; Samcová, Eva; Stulík, Karel

    2011-01-24

    A mixture of 29 organic acids (OAs) occurring in urine was analyzed by capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4)D) and UV photometric detection. The optimized analytical system involved a 100 cm long polyacrylamide-coated capillary (50 μm i.d.) and the background electrolyte of 20mM 2-morpholinoethanesulfonic acid (MES)/NaOH+10% (v/v) methanol, pH 6.0 (pH is related to the 20mM MES/NaOH buffer in water). The LOD values obtained by C(4)D for the OAs which do not absorb UV radiation range from 0.6 μM (oxalic acid) to 6.8 μM (pyruvic acid); those obtained by UV photometry for the remaining OAs range from 2.9 μM (5-hydroxy-3-indoleacetic acid) to 10.2 μM (uric acid). The repeatability of the procedure developed is characterized by the coefficients of variation, which vary between 0.3% (tartaric acid) and 0.6% (5-hydroxy-3-indoleacetic acid) for the migration time and between 1.3% (tartaric acid) and 3.5% (lactic acid) for the peak area. The procedure permitted quantitation of 20 OAs in a real urine sample and was applied to monitoring of the occurrence of the inborn metabolic fault of methylmalonic aciduria.

  17. Large volume sample stacking for rapid and sensitive determination of antidiabetic drug metformin in human urine and serum by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Tůma, Petr

    2014-06-06

    Two CE methods with contactless conductivity detection have been developed for determining the oral antidiabetic drug metformin in human urine and blood. The determination of metformin is performed on a separation capillary with an effective length of 14 cm, using a maximum voltage of 30 kV and with a small injection of 50-fold diluted urine into the capillary. Under these conditions, the migration time of metformin is 35s and the LOD is 0.3 μM. Large-volume sample stacking was used to determine low metformin levels in serum. The injection of a sample of serum deproteinized with acetonitrile was 10 times greater compared to the injected amount of urine. This enabled reduction of the LOD to 0.03 μM and the metformin migration time equalled 86 s. The undesirable solvent from sample zone was forced out of the capillary to ensure rapidity and good repeatability of the determination. The RSD values for the migration time are 0.1% for urine and 0.7% for serum; RSD for the peak areas equalled 1.4% for urine and 2.6% for serum. The developed CE technique was tested on performance of routine analyses of metformin in the urine and serum of patients suffering from type II diabetes mellitus. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Running buffers for determination of chromium(VI)/(III), cobalt(II) and zinc(II) in complex matrices by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Wang, Li-Shi; Zhang, Shui-Feng; Dang, Zhi; Liu, Xiao-Xiao; Huang, Xin-Jian; Xiao, Ming-Wei; Chen, Zuan-Guang

    2007-06-15

    Complex matrices and rather high acidity in environmental samples are often the impelling challenges for the used running buffers of capillary electrophoresis. Twelve binary acid-base buffers were evaluated for separation of Cr(VI)/Cr(III), Co(2+) and Zn(2+) in a sample containing various salts by capillary electrophoresis with contactless conductivity detector. The malic acid (MA) systems including MA-His (histidine), MA-Arg (arginine) and MA-Tris (tris(hydroxymethyl)aminomethane) were selected as the candidates with powerful separation efficiency and good response sensitivity. In the MA-Tris buffer, optimization were further carried out in terms of the pH value and the concentration of MA, and the optimal conditions were obtained as 6mM MA-Tris and 2mM 18-crown-6 at pH 3.5. Furthermore, a real application was demonstrated by analyzing the plating rinse water (pH 0.8), in which the Ca(2+), Na(+), Cr(VI)/Cr(III), Co(2+) and Zn(2+) were all detected by adjusting at pH 3.5 with 5% (v/v) diluent ammonia. Both the cations, e.g., K(+), Ca(2+), Na(+), Mg(2+), and the common high concentration anions in the sample, e.g., Cl(-), SO(4)(2-) and NO(3)(-) did not cause any disturbance to the concerned analytes.

  19. Ion-pair liquid-liquid-liquid microextraction of nerve agent degradation products followed by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Xu, Li; Gong, Xiao Yang; Lee, Hian Kee; Hauser, Peter C

    2008-09-26

    The four nerve agent degradation products methylphosphonic acid (MPA), ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA) and cyclohexyl methylphosphonic acid (CMPA) have been successfully extracted from aqueous sample solution by ion-pair liquid-liquid-liquid microextraction. In this procedure, the target analytes in the sample solution were converted into their ion-pair complexes with tri-n-butyl amine and then extracted by an organic solvent (1-octanol) layer on top of the sample solution. Simultaneously, the analytes were back-extracted into a drop of an aqueous acceptor solution which was suspended in the organic phase at a microsyringe needle tip. The factors influential to extraction: type of organic solvent, type of ion-pair reagent and its concentration, pH values of sample solution and acceptor aqueous phase, stirring rate and extraction time were investigated in detail. After extraction, the drop of the acceptor solution was withdrawn into the syringe and injected into a capillary electrophoresis system for analysis. Using contactless conductivity detection, direct quantification of these compounds is possible. Moreover, large-volume sample injection was employed for further preconcentration. Improvements in the limits of detection between 2.5 and 4 orders of magnitude could be achieved and concentrations at the ng/mL level can be determined. This newly established approach was successfully applied to a spiked river water sample.

  20. Pressure-assisted introduction of urine samples into a short capillary for electrophoretic separation with contactless conductivity and UV spectrometry detection.

    PubMed

    Makrlíková, Anna; Opekar, František; Tůma, Petr

    2015-08-01

    A computer-controlled hydrodynamic sample introduction method has been proposed for short-capillary electrophoresis. In the method, the BGE flushes sample from the loop of a six-way sampling valve and is carried to the injection end of the capillary. A short pressure impulse is generated in the electrolyte stream at the time when the sample zone is at the capillary, leading to injection of the sample into the capillary. Then the electrolyte flow is stopped and the separation voltage is turned on. This way of sample introduction does not involve movement of the capillary and both of its ends remain constantly in the solution during both sample injection and separation. The amount of sample introduced to the capillary is controlled by the duration of the pressure pulse. The new sample introduction method was tested in the determination of ammonia, creatinine, uric acid, and hippuric acid in human urine. The determination was performed in a capillary with an overall length of 10.5 cm, in two BGEs with compositions 50 mM MES + 5 mM NaOH (pH 5.1) and 1 M acetic acid + 1.5 mM crown ether 18-crown-6 (pH 2.4). A dual contactless conductivity/UV spectrometric detector was used for the detection.

  1. The use of capillary electrophoresis with contactless conductivity detection for sensitive determination of stevioside and rebaudioside A in foods and beverages.

    PubMed

    Pavlíček, Václav; Tůma, Petr

    2017-03-15

    Two electrophoretic methods with contactless conductivity detection have been developed for determination of the content of rebaudioside A and stevioside in samples of sweeteners and beverages prepared from extracts of the plant Stevia rebaudiana Bertoni. The total content of rebaudioside A and stevioside can be determined in a fused silica capillary with an inner diameter of 10μm and total length of 31.5cm in optimised background electrolyte with the composition 170mM H3BO3/LiOH (pH 9.0). The combined peak of the two glucosides is characterised by a migration time of 54s, which completely separates it from EOF. INST coating solution in an amount of 0.5% v/v, which effectively suppresses the electroosmotic flow, was added to the background electrolyte for mutual separation of rebaudioside A and stevioside. The CE method with suppression of EOF is characterised by complete separation of rebaudioside A and stevioside, LOD is 0.3mg/L (0.1μM). Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Efficient sample clean-up and online preconcentration for sensitive determination of melamine in milk samples by capillary electrophoresis with contactless conductivity detection.

    PubMed

    Ji, Yan-ling; Chen, Xiao-wei; Zhang, Zhu-bao; Li, Jing; Xie, Tian-yao

    2014-10-01

    Based on an efficient sample clean-up and field-amplified sample injection online preconcentration technique in capillary electrophoresis with contactless conductivity detection, a new analytical method for the sensitive determination of melamine in milk samples was established. In order to remove the complex matrix interference, which resulted in a serious problem during field-amplified sample injection, liquid-liquid extraction was utilized. As a result, liquid-liquid extraction provides excellent sample clean-up efficiency when ethyl acetate was used as organic extraction by adjusting the pH of the sample solution to 9.5. Both inorganic salts and biological macromolecules are effectively removed by liquid-liquid extraction. The sample clean-up procedure, capillary electrophoresis separation parameters and field-amplified sample injection conditions are discussed in detail. The capillary electrophoresis separation was achieved within 5 min under the following conditions: an uncoated fused-silica capillary, 12 mM HAc + 10 mM NaAc (pH = 4.6) as running buffer, separation voltage of +13 kV, electrokinetic injection of +12 kV × 10 s. Preliminary validation of the method performance with spiked melamine provided recoveries >90%, with limits of detection and quantification of 0.015 and 0.050 mg/kg, respectively. The relative standard deviations of intra- and inter-day were below 6%. This newly developed method is sensitive and cost effective, therefore, suitable for screening of melamine contamination in milk products.

  3. Conductance and Kondo Interference beyond Proportional Coupling

    NASA Astrophysics Data System (ADS)

    Dias da Silva, Luis G. G. V.; Lewenkopf, Caio H.; Vernek, Edson; Ferreira, Gerson J.; Ulloa, Sergio E.

    2017-09-01

    The transport properties of nanostructured systems are deeply affected by the geometry of the effective connections to metallic leads. In this work we derive a conductance expression for a class of interacting systems whose connectivity geometries do not meet the Meir-Wingreen proportional coupling condition. As an interesting application, we consider a quantum dot connected coherently to tunable electronic cavity modes. The structure is shown to exhibit a well-defined Kondo effect over a wide range of coupling strengths between the two subsystems. In agreement with recent experimental results, the calculated conductance curves exhibit strong modulations and asymmetric behavior as different cavity modes are swept through the Fermi level. These conductance modulations occur, however, while maintaining robust Kondo singlet correlations of the dot with the electronic reservoir, a direct consequence of the lopsided nature of the device.

  4. Magnetically coupled gear based drive mechanism for contactless continuous rotation using superconducting magnetic bearing below 10 K

    NASA Astrophysics Data System (ADS)

    Matsumura, T.; Sakurai, Y.; Kataza, H.; Utsunomiya, S.; Yamamoto, R.

    2016-11-01

    We present the design and mechanical performances of a magnetically coupled gear mechanism to drive a levitating rotor magnet of a superconducting magnetic bearing (SMB). The SMB consists of a ring-shaped high-temperature superconducting array (YBCO) and a ring-shaped permanent magnet. This rotational system is designed to operate below 10 K, and thus the design philosophy is to minimize any potential source of heat dissipation. While an SMB provides only a functionality of namely a bearing, it requires a mechanism to drive a rotational motion. We introduce a simple implementation of a magnetically coupled gears between a stator and a rotor. This enables to achieve enough torque to drive a levitating rotor without slip at the rotation frequency of about 1 Hz below 10 K. The rotational variation between the rotor and the drive gear is synchronised within σ = 0.019 Hz. The development of this mechanism is a part of the program to develop a testbed in order to evaluate a prototype half-wave plate based polarization modulator for future space missions. The successful development allows this modulator to be a candidate for an instrument to probe the cosmic inflation by measuring the cosmic microwave background polarization.

  5. Simultaneous and rapid determination of caffeine and taurine in energy drinks by MEKC in a short capillary with dual contactless conductivity/photometry detection.

    PubMed

    Vochyánová, Blanka; Opekar, František; Tůma, Petr

    2014-06-01

    A method has been developed for the simultaneous determination of taurine and caffeine using a laboratory-made instrument enabling separation analysis in a short 10.5 cm capillary. The substances are detected using a contactless conductometry/ultraviolet (UV) photometry detector that enables recording both signals at one place in the capillary. The separation of caffeine and taurine was performed using the MEKC technique in a BGE with the composition 40 mM CHES, 15 mM NaOH, and 50 mM SDS, pH 9.36. Under these conditions, the migration time of caffeine is 43 s and of taurine 60 s; LOD for caffeine is 4 mg/L using photometric detection and LOD for taurine is 24 mg/L using contactless conductometric detection. The standard addition method was used for determination in Red Bull energy drink of caffeine 317 mg/L and taurine 3860 mg/L; the contents in Kamikaze drink were 468 mg/L caffeine and 4110 mg/L taurine. The determined values are in good agreement with the declared contents of these substances. RSD does not exceed 3%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. A new contactless impedance sensor for void fraction measurement of gas-liquid two-phase flow

    NASA Astrophysics Data System (ADS)

    Ji, Haifeng; Chang, Ya; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

    2016-12-01

    With impedance elimination principle and phase sensitive demodulation (PSD) technique, this work aims to develop a new contactless impedance sensor, which is suitable for the void fraction measurement of gas-liquid two-phase flow. The impedance elimination principle is used to overcome the unfavorable influences of the coupling capacitances, i.e. the capacitive reactances of the coupling capacitances are eliminated by the inductive reactance of an introduced inductor. PSD technique is used to implement the impedance measurement. Unlike the conventional conductance/impedance sensors which use the equivalent conductance (the real part of the impedance) or the amplitude of the impedance of gas-liquid two-phase flow, the new contactless impedance sensor makes full use of the total impedance information of gas-liquid two-phase flow (including the amplitude, the real part and the imaginary part of the impedance, especially the imaginary part) to implement the void fraction measurement. As a preliminary study, to verify the effectiveness of the new contactless impedance sensor, two prototypes (with different inner diameters of 17.0 mm and 22.0 mm) are developed and experiments are carried out. Two typical flow patterns (bubble flow and stratified flow) of gas-liquid two-phase flow are investigated. The experimental results show that the new contactless impedance sensor is successful and effective. Compared with the conventional conductance/impedance sensors, the new contactless impedance sensor can avoid polarization effect and electrochemical erosion effect. The total impedance information is used and the void fraction measurement performance of the new sensor is satisfactory. The experimental results also indicate that the imaginary part of the impedance of gas-liquid two-phase flow is very useful for the void fraction measurement. Making full use of the total impedance information of gas-liquid two-phase flow can effectively improve the void fraction measurement

  7. COBRA contactless detumbling

    NASA Astrophysics Data System (ADS)

    Peters, Thomas V.; Escorial Olmos, Diego

    2016-09-01

    COBRA is the proposed technique to control the motion of a non-cooperative target by means of the interaction between the thruster exhaust gases from the chaser and the target object. In the original ESA SysNova study, the COBRA concept was investigated as an active debris removal system, using contactless technology to deorbit a space debris object and to control its attitude. It was found that the concept is more effective for controlling the attitude of a debris object. An on-orbit experiment was proposed to have a chaser modify the attitude state of a space object in ESA's COBRA IRIDES project, which has now been canceled due to the lack of propellant in the chaser spacecraft. This study presents the results of an internal follow-up study on how to effectively use the COBRA concept for detumbling a large debris object and controlling its attitude motion prior to capture operations in an active debris removal mission.

  8. Capillary electrophoresis coupled to contactless conductivity detection for analysis of amino acids of agricultural interest in composting.

    PubMed

    Cappelini, Luciana Teresa Dias; de Fátima Menegoci Eugênio, Patrícia; Leão, Paulo Augusto Gomes Carneiro; Alberice, Juliana Vieira; Urbaczek, Ana Carolina; Assunção, Nilson Antonio; Juliano, Luiz; Carrilho, Emanuel

    2016-10-01

    Composting is a sustainable approach to manage animal and vegetal waste generated in the Fundação Parque Zoológico de São Paulo. The resulting compost is often used in ZOO's premises as an organic fertilizer for the production of vegetables, which is further used to feed the animals. The composting product provides many forms of mineral and also amino acids (AA) that are absorbed by plants as nutrients. Since most amino acids absorb only slightly or not at all in the UV wavelengths, we developed a method for the determination of AA of agricultural interest in the composting samples. Due to the complexity of samples, we used ion exchange chromatography for the purification of AA prior to analysis. The proposed CZE-C(4) D method allowed a separation of the AA in a short analysis time (less than 3.0 min), with great linearity (with R(2) ranging from 0.993 to 0.998). Using a BGE of 10 mmol/L TEA, reduction of high-frequency noise and lower baseline fluctuations were obtained. The LOQ for the five AA were around 35 μmol/L, and were adequate for our purpose. In addition, the method showed good precision (RSD of peak area and migration time less than 1.55 and 1.16%, respectively). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. A novel CE microchip with micro pillars column & double-L injection design for Capacitance Coupled Contactless Conductivity detection technology

    NASA Astrophysics Data System (ADS)

    Wang, Yineng; Messina, Walter; Cao, Xi; Hogan, Anna; van Zalen, Ed; Moore, Eric

    2016-10-01

    This novel capillary electrophoresis microchip, or also known as μTAS (micro total analysis system) was designed to separate complex aqueous based compounds, similar to commercial CE & microchip (capillary electrophoresis) systems, but more compact. This system can be potentially used for mobile/portable chemical analysis equipment. Un-doped silicon wafer & ultra-thin borofloat glass (Pyrex) wafers have been used to fabricate the device. Double-L injection feature, micro pillars column, bypass separation channel & hybrid- referenced C4D electrodes were designed to achieve a high SNR (signal to noise ratio), easy- separation, for a durable and reusable μTAS for CE use.

  10. Multilayer contactless dielectrophoresis: theoretical considerations.

    PubMed

    Sano, Michael B; Salmanzadeh, Alireza; Davalos, Rafael V

    2012-07-01

    Dielectrophoresis (DEP), the movement of dielectric particles in a nonuniform electric field, is of particular interest due to its ability to manipulate particles based on their unique electrical properties. Contactless DEP (cDEP) is an extension of traditional and insulator-based DEP topologies. The devices consist of a sample channel and fluid electrode channels filled with a highly conductive media. A thin insulating membrane between the sample channel and the fluid electrode channels serves to isolate the sample from direct contact with metal electrodes. Here we investigate, for the first time, the properties of multilayer devices in which the sample and electrode channels occupy distinct layers. Simulations are conducted using commercially available finite element software and a less computationally demanding numerical approximation is presented and validated. We show that devices can be created that achieve a similar level of electrical performance to other cDEP devices presented in the literature while increasing fluid throughput. We conclude, based on these models, that the ultimate limiting factors in device performance resides in breakdown voltage of the barrier material and the ability to generate high-voltage, high-frequency signals. Finally, we demonstrate trapping of MDA-MB-231 breast cancer cells in a prototype device at a flow rate of 1.0 mL/h when 250 V(RMS) at 600 kHz is applied. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Highly Efficient Contactless Electrical Energy Transmission System

    NASA Astrophysics Data System (ADS)

    Ayano, Hideki; Nagase, Hiroshi; Inaba, Hiromi

    This paper proposes a new concept for a contactless electrical energy transmission system for an elevator and an automated guided vehicle. The system has rechargeable batteries on the car and electrical energy is supplied at a specific place. When electric power is supplied to the car, it runs automatically and approaches the battery charger. Therefore, a comparatively large gap is needed between the primary transformer at the battery charger and the secondary transformer on the car in order to prevent damage which would be caused by a collision. In this case, a drop of the transformer coupling rate due to the large gap must be prevented. In conventional contactless electrical energy transmission technology, since electric power is received by a pick-up coil from a power line, a large-sized transformer is required. And when the distance over which the car runs is long, the copper loss of the line also increases. The developed system adopts a high frequency inverter using a soft switching method to miniaturize the transformer. The system has a coupling rate of 0.88 for a transformer gap length of 10mm and can operate at 91% efficiency.

  12. Quantum Ising model coupled with conducting electrons

    NASA Astrophysics Data System (ADS)

    Yamashita, Yasufumi; Yonemitsu, Kenji

    2005-01-01

    The effect of photo-doping on the quantum paraelectric SrTiO3 is studied by using the one-dimensional quantum Ising model, where the Ising spin describes the effective lattice polarization of an optical phonon. Two types of electron-phonon couplings are introduced through the modulation of transfer integral via lattice deformations. After the exact diagonalization and the perturbation studies, we find that photo-induced low-density carriers can drastically alter quantum fluctuations when the system locates near the quantum critical point between the quantum para- and ferro-electric phases.

  13. Capillary electrophoresis with contactless conductivity detection for the quantification of fluoride in lithium ion battery electrolytes and in ionic liquids-A comparison to the results gained with a fluoride ion-selective electrode.

    PubMed

    Pyschik, Marcelina; Klein-Hitpaß, Marcel; Girod, Sabrina; Winter, Martin; Nowak, Sascha

    2017-02-01

    In this study, an optimized method using capillary electrophoresis (CE) with a direct contactless conductivity detector (C(4) D) for a new application field is presented for the quantification of fluoride in common used lithium ion battery (LIB) electrolyte using LiPF6 in organic carbonate solvents and in ionic liquids (ILs) after contacted to Li metal. The method development for finding the right buffer and the suitable CE conditions for the quantification of fluoride was investigated. The results of the concentration of fluoride in different LIB electrolyte samples were compared to the results from the ion-selective electrode (ISE). The relative standard deviations (RSDs) and recovery rates for fluoride were obtained with a very high accuracy in both methods. The results of the fluoride concentration in the LIB electrolytes were in very good agreement for both methods. In addition, the limit of detection (LOD) and limit of quantification (LOQ) values were determined for the CE method. The CE method has been applied also for the quantification of fluoride in ILs. In the fresh IL sample, the concentration of fluoride was under the LOD. Another sample of the IL mixed with Li metal has been investigated as well. It was possible to quantify the fluoride concentration in this sample. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Ephaptic coupling rescues conduction failure in weakly coupled cardiac tissue with voltage-gated gap junctions.

    PubMed

    Weinberg, S H

    2017-09-01

    Electrical conduction in cardiac tissue is usually considered to be primarily facilitated by gap junctions, providing a pathway between the intracellular spaces of neighboring cells. However, recent studies have highlighted the role of coupling via extracellular electric fields, also known as ephaptic coupling, particularly in the setting of reduced gap junction expression. Further, in the setting of reduced gap junctional coupling, voltage-dependent gating of gap junctions, an oft-neglected biophysical property in computational studies, produces a positive feedback that promotes conduction failure. We hypothesized that ephaptic coupling can break the positive feedback loop and rescue conduction failure in weakly coupled cardiac tissue. In a computational tissue model incorporating voltage-gated gap junctions and ephaptic coupling, we demonstrate that ephaptic coupling can rescue conduction failure in weakly coupled tissue. Further, ephaptic coupling increased conduction velocity in weakly coupled tissue, and importantly, reduced the minimum gap junctional coupling necessary for conduction, most prominently at fast pacing rates. Finally, we find that, although neglecting gap junction voltage-gating results in negligible differences in well coupled tissue, more significant differences occur in weakly coupled tissue, greatly underestimating the minimal gap junctional coupling that can maintain conduction. Our study suggests that ephaptic coupling plays a conduction-preserving role, particularly at rapid heart rates.

  15. Ephaptic coupling rescues conduction failure in weakly coupled cardiac tissue with voltage-gated gap junctions

    NASA Astrophysics Data System (ADS)

    Weinberg, S. H.

    2017-09-01

    Electrical conduction in cardiac tissue is usually considered to be primarily facilitated by gap junctions, providing a pathway between the intracellular spaces of neighboring cells. However, recent studies have highlighted the role of coupling via extracellular electric fields, also known as ephaptic coupling, particularly in the setting of reduced gap junction expression. Further, in the setting of reduced gap junctional coupling, voltage-dependent gating of gap junctions, an oft-neglected biophysical property in computational studies, produces a positive feedback that promotes conduction failure. We hypothesized that ephaptic coupling can break the positive feedback loop and rescue conduction failure in weakly coupled cardiac tissue. In a computational tissue model incorporating voltage-gated gap junctions and ephaptic coupling, we demonstrate that ephaptic coupling can rescue conduction failure in weakly coupled tissue. Further, ephaptic coupling increased conduction velocity in weakly coupled tissue, and importantly, reduced the minimum gap junctional coupling necessary for conduction, most prominently at fast pacing rates. Finally, we find that, although neglecting gap junction voltage-gating results in negligible differences in well coupled tissue, more significant differences occur in weakly coupled tissue, greatly underestimating the minimal gap junctional coupling that can maintain conduction. Our study suggests that ephaptic coupling plays a conduction-preserving role, particularly at rapid heart rates.

  16. Contactless Calorimetry for Levitated Samples

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Dokko, W.

    1986-01-01

    Temperature and specific heat of hot sample measured with pyrometer in proposed experimental technique. Technique intended expecially for contactless calorimetry of such materials as undercooled molten alloys, samples of which must be levitated to prevent contamination and premature crystallization. Contactless calorimetry technique enables data to be taken over entire undercooling temperature range with only one sample. Technique proves valuable in study of undercooling because difference in specific heat between undercooled-liquid and crystalline phases at same temperature provides driving force to convert metastable undercooled phase to stable crystalline phase.

  17. Contactless Calorimetry for Levitated Samples

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Dokko, W.

    1986-01-01

    Temperature and specific heat of hot sample measured with pyrometer in proposed experimental technique. Technique intended expecially for contactless calorimetry of such materials as undercooled molten alloys, samples of which must be levitated to prevent contamination and premature crystallization. Contactless calorimetry technique enables data to be taken over entire undercooling temperature range with only one sample. Technique proves valuable in study of undercooling because difference in specific heat between undercooled-liquid and crystalline phases at same temperature provides driving force to convert metastable undercooled phase to stable crystalline phase.

  18. Contactless nonlinear optics mediated by long-range Rydberg interactions

    NASA Astrophysics Data System (ADS)

    Busche, Hannes; Huillery, Paul; Ball, Simon W.; Ilieva, Teodora; Jones, Matthew P. A.; Adams, Charles S.

    2017-07-01

    In conventional nonlinear optics, linear quantum optics, and cavity quantum electrodynamics to create effective photon-photon interactions photons must have, at one time, interacted with matter inside a common medium. In contrast, in Rydberg quantum optics, optical photons are coherently and reversibly mapped onto collective atomic Rydberg excitations, giving rise to dipole-mediated effective photon-photon interactions that are long range. Consequently, a spatial overlap between the light modes is no longer required. We demonstrate such a contactless coupling between photons stored as collective Rydberg excitations in spatially separate optical media. The potential induced by each photon modifies the retrieval mode of its neighbour, leading to correlations between them. We measure these correlations as a function of interaction strength, distance and storage time, demonstrating an effective interaction between photons separated by 15 times their wavelength. Contactless effective photon-photon interactions are relevant for scalable multichannel photonic devices and the study of strongly correlated many-body dynamics using light.

  19. Contactless impedance sensors and their application to flow measurements.

    PubMed

    Opekar, František; Tůma, Petr; Stulík, Karel

    2013-02-27

    The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors), the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal) on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined.

  20. Contactless Impedance Sensors and Their Application to Flow Measurements

    PubMed Central

    Opekar, František; Tůma, Petr; Štulík, Karel

    2013-01-01

    The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors), the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal) on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined. PMID:23447011

  1. Thermopower and thermal conductance through parallel coupled quantum dots

    NASA Astrophysics Data System (ADS)

    Franco, R.; Silva-Valencia, J.; Figueira, M. S.

    2008-04-01

    We study the thermoelectric transport properties through two parallel coupled, gate-defined quantum dots (QDs), in the framework of the X-boson treatment for the impurity Anderson model. We compute the thermopower S, the thermal conductance κ, the electrical conductance G, and the product of the thermoelectric figure of merit and the temperature ZT, as function of the dot energy. We concentrate the calculations on ZT, that is, a measure of the usefulness of materials or devices as thermopower generators or cooling systems. If the coupling between the QDs is weak, ZT is greater than 1 when T ≃Δ (Δ is the mixing width between the QD and the leads) but when the system is coupled, the second dot can tune the temperature region where ZT >1. This result increases the possibilities of practical application of the system in mesoscopic cooling process.

  2. Optical contactless measurement of semiconductor thermoelectric transport properties (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Gibelli, Francois; Lombez, Laurent; Guillemoles, Jean-François

    2017-04-01

    In view of the combinatorial approach to discovery of new thermoelectric materials, it is highly desirable to have fast measurement techniques, if possible with capabilities to access local fluctuations or gradients in material properties. Using the generalized Planck& #39;s law of radiation [1] for fitting the photoluminescence spectra is the most appropriate technique to access the quasi Fermi level splitting and the temperature of the carriers in a semiconductor. These two parameters enable to determine Seebeck coefficients for the material as a new photo-Seebeck effect [2]. The absolutely calibrated photoluminescence intensity profile[3] with the spatial coordinates combined with Callen coupled transport equations and with the kinetic expression of the transport parameters under the relaxation time approximation enable us to determine: the Seebeck coefficient, the electrical conductivity, the thermal electron and hole conductivity, the mobilities, the diffusion coefficients and the heat transferred from the carriers to the lattice. All these parameters can be obtained either for electrons or for holes[4], even simultaneously, for intrinsic semiconductor in ambipolar regime. The method has been applied to a multi-quantum well structure of InGaAsP. Since the luminescence comes from the wells, this method enables to access the transport properties in the plane of the wells inside the whole structure. Since photoluminescence does not require p-n junction nor high electrical conductivities for the measurement, this optical contactless measurement technique of thermoelectrinc transport parameters involving quasi-equilibrium carriers enables to access properties inside a given layer of the whole structure or in materials with very low conductivities. We will also show the perspectives offered for the research of new thermoelectric materials. [1] Würfel, J. Phys. C : Solid State Phys., 1982 [2] Gibelli et al., Phys. Rev. Appl., 5 (2) 2016 Tauc, Czech J Phys, 1955 [3

  3. Simplified Model of Contactless Air-Core Power Alternator and Transfer Using Ideal Superconductor

    NASA Astrophysics Data System (ADS)

    Jin, Jian Xun; Chen, Xiao Yuan

    The feasibility study of a contactless power transfer (CPT) system using high temperature superconducting (HTS) DC windings has been carried out. The analyses on two HTS CPT application schemes with iron-core and air-core loosely-coupled transformer structures indicate that the introduction of HTS DC windings makes the large-current coupling CPT available for improving the transfer power and efficiency, promising for large-power AC and DC contactless loads, and its transfer efficiency almost coincides with efficiency of the cooperated motor. The design considerations and procedures of the HTS CPT system have also been discussed.

  4. Rapid contactless thermometry with submilli-Kelvin resolution

    NASA Astrophysics Data System (ADS)

    Coffey, T.; Mielke, C. H.; Ruminer, P.; Migliori, A.; Kim, D.; Kim, K. H.; Moritomo, Y.

    2006-07-01

    We present a contactless method of detecting small changes in the surface temperature of metallic samples over a short time period. The thermometry method incorporates a contactless heater and simplifies sample preparation requirements for calorimetric measurements. We demonstrate that we can measure small temperature shifts (250μK) in 5ms at midrange temperatures (155K). This method does not serve as a conventional thermometer but as an in situ thermometer useful for narrow temperature ranges, such as the region of a phase transition (often exploited in bolometers). The manganite material Nd0.5Sr0.5MnO3 was chosen as a test material for our experiments because it is a well characterized material where resistivity and magnetization [Kuwakara et al., Science 270, 961 (1995)] and thermal conductivity [Kim et al., American Physical Society March Meeting, W24.009 (2004)] have been previously measured and the material undergoes a metal-insulator transition.

  5. Longitudinal optical and spin Hall conductivities of Rashba conducting strips coupled to ferromagnetic and antiferromagnetic layers

    NASA Astrophysics Data System (ADS)

    Riera, José A.

    2017-01-01

    A system composed of a conducting planar strip with Rashba spin-orbit coupling (RSOC), magnetically coupled to a layer of localized magnetic moments, at equilibrium, is studied within a microscopic Hamiltonian with numerical techniques at zero temperature in the clean limit. In particular, transport properties for the cases of ferromagnetic (FM) and antiferromagnetic (AFM) coupled layers are computed in linear response on strips of varying width. Some behaviors observed for these properties are consistent with the ones observed for the corresponding Rashba helical currents. The case of uncoupled Rashba strips is also studied for comparison. In the case of Rashba strips coupled to an AFM localized order, results for the longitudinal dc conductivity, for small strip widths, suggest the proximity to a metal-insulator transition. More interesting, in the proximity of this transition, and in general at intermediate values of the RSOC, a large spin Hall conductivity is observed that is two orders of magnitude larger than the one for the FM order for the same values of the RSOC and strip widths. There are clearly two different regimes for small and for large RSOC, which is also present in the behavior of Rashba helical currents. Different contributions to the optical and the spin Hall conductivities, according to a new classification of inter- or intraband origin proposed for planar strips in the clean limit, or coming from the hopping or spin-orbit terms of the Hamiltonian, are examined. Finally, the effects of different orientation of the coupled magnetic moments will be also studied.

  6. Application of Micro-Electro-Mechanical Sensors Contactless NDT of Concrete Structures

    PubMed Central

    Ham, Suyun; Popovics, John S.

    2015-01-01

    The utility of micro-electro-mechanical sensors (MEMS) for application in air-coupled (contactless or noncontact) sensing to concrete nondestructive testing (NDT) is studied in this paper. The fundamental operation and characteristics of MEMS are first described. Then application of MEMS sensors toward established concrete test methods, including vibration resonance, impact-echo, ultrasonic surface wave, and multi-channel analysis of surface waves (MASW), is demonstrated. In each test application, the performance of MEMS is compared with conventional contactless and contact sensing technology. Favorable performance of the MEMS sensors demonstrates the potential of the technology for applied contactless NDT efforts. Objective: To illustrate the utility of air-coupled MEMS sensors for concrete NDT, as compared with conventional sensor technology. PMID:25897497

  7. Application of Micro-Electro-Mechanical Sensors Contactless NDT of Concrete Structures.

    PubMed

    Ham, Suyun; Popovics, John S

    2015-04-17

    The utility of micro-electro-mechanical sensors (MEMS) for application in air-coupled (contactless or noncontact) sensing to concrete nondestructive testing (NDT) is studied in this paper. The fundamental operation and characteristics of MEMS are first described. Then application of MEMS sensors toward established concrete test methods, including vibration resonance, impact-echo, ultrasonic surface wave, and multi-channel analysis of surface waves (MASW), is demonstrated. In each test application, the performance of MEMS is compared with conventional contactless and contact sensing technology. Favorable performance of the MEMS sensors demonstrates the potential of the technology for applied contactless NDT efforts. To illustrate the utility of air-coupled MEMS sensors for concrete NDT, as compared with conventional sensor technology.

  8. Calibration of Contactless Pulse Oximetry

    PubMed Central

    Bartula, Marek; Bresch, Erik; Rocque, Mukul; Meftah, Mohammed; Kirenko, Ihor

    2017-01-01

    BACKGROUND: Contactless, camera-based photoplethysmography (PPG) interrogates shallower skin layers than conventional contact probes, either transmissive or reflective. This raises questions on the calibratability of camera-based pulse oximetry. METHODS: We made video recordings of the foreheads of 41 healthy adults at 660 and 840 nm, and remote PPG signals were extracted. Subjects were in normoxic, hypoxic, and low temperature conditions. Ratio-of-ratios were compared to reference Spo2 from 4 contact probes. RESULTS: A calibration curve based on artifact-free data was determined for a population of 26 individuals. For an Spo2 range of approximately 83% to 100% and discarding short-term errors, a root mean square error of 1.15% was found with an upper 99% one-sided confidence limit of 1.65%. Under normoxic conditions, a decrease in ambient temperature from 23 to 7°C resulted in a calibration error of 0.1% (±1.3%, 99% confidence interval) based on measurements for 3 subjects. PPG signal strengths varied strongly among individuals from about 0.9 × 10−3 to 4.6 × 10−3 for the infrared wavelength. CONCLUSIONS: For healthy adults, the results present strong evidence that camera-based contactless pulse oximetry is fundamentally feasible because long-term (eg, 10 minutes) error stemming from variation among individuals expressed as A*rms is significantly lower (<1.65%) than that required by the International Organization for Standardization standard (<4%) with the notion that short-term errors should be added. A first illustration of such errors has been provided with A**rms = 2.54% for 40 individuals, including 6 with dark skin. Low signal strength and subject motion present critical challenges that will have to be addressed to make camera-based pulse oximetry practically feasible. PMID:27258081

  9. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan; Katsouros, Joseph

    1999-11-01

    We measure the electrical conductivity of strongly coupled plasmas of various metals, including aluminum, iron, copper, and tungsten, in the temperature range 6-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. These plasmas may have coupling parameters (ratio of mean interparticle Coulomb energy to mean kinetic energy) ranging from as high as 50 down to unity. Plasmas are created by rapid vaporization of metal wire in a water bath which act as a tamper. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL SESAME database [1], and a brightness temperature may be obtained from radiation measurements. The column resistance is determined from time-resolved voltage and current measurements. Results of conductivity measurements will be shown and compared with the predictions of conductivity theories. 1.SESAME: The Los Alamos National Laboratory Equation of State Database, Report LA-UR-92-3407, ed. S. P. Lyon and J. D. Johnson, Group T-1.

  10. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan

    1998-11-01

    The coupling parameter Γ=e^2/akT, where a is the mean ion-ion separation, expresses the ratio of the mean potential energy of ions in a plasma to their mean kinetic energy. Plasma is said to be strongly coupled when Γ is greater than unity. Transport properties of strongly coupled plasmas are of interest in the study of the structure of dense astrophysical objects and gaseous planetary interiors, as well as in arcs and laser-produced plasmas. We are attempting to measure the electrical conductivity of strongly coupled metal plasmas (copper, tungsten and aluminum) in the temperature range 8-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. They may have coupling parameters Γ ranging from as high as 100 down to unity Plasmas are created by rapid vaporization of metal wire in a glass capillary or in a water bath which act as a tamper, slowing the expansion rate. The effect of the tamper is to force the interior pressure of the plasma to be fairly uniform. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL sesame database(SESAME: The Los Alamos National Laboratory Equation of State Database, Report No. LA-UR-92-3407, Ed. S. P. Lyon and J. D. Johnson, Group T-1 (unpublished)), and a brightness temperature may be obtained from radiation measurements. The column resistance is simply determined from time-resolved voltage and current measurements. For temperatures less than about 14,000K, as density decreases from the highest values measured, the conductivity falls roughly as the cube of density, reaches a minimum, and subsequently rises to approach the Spitzer prediction at low density. The rate of change of conductivity with density becomes less rapid as temperature increases, and the minimum becomes less pronounced, disappearing altogether above

  11. Space applications for contactless coilguns

    NASA Astrophysics Data System (ADS)

    Lipinski, R. J.; Beard, S.; Boyes, J.; Cnare, E. C.; Cowan, M.; Duggin, B. W.; Kaye, R. J.; Morgan, R. M.; Outka, D.; Potter, D.

    Two space applications are considered for (electrically) contactless coilguns: launch of small satellites into low-earth orbit, and launch of lunar liquid oxygen (LLOX) from the moon to the stationary Lagrangian point L2. For the earth-to-orbit (ETO) application, the baseline conceptual design consists of a 960-m long gun sited in a tunnel at 25 degrees inclination. The gun launches an 1820-kg package that includes a 100-kg satellite and a 650-kg boost rocket for orbital insertion. For the lunar application, the launcher is 200 m long. A 100-kg load of LLOX is packaged in a 10-kg fiber-wrapped tank, accelerated at 2 kgees in an aluminum bucket (armature), and launched at 2.33 km/s at 30-minute intervals. The canisters arrive at L2 2.97 days later and are captured by robotic tugs that deliver them to a fuel depot. The total mass of LLOX derived per year is 867 Mg (metric tons).

  12. Role of ionospheric conductance in magnetosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Tapas

    Magnetosphere-ionosphere (MI) coupling has been studied for a long time. However, not much work has been done on a systematic understanding of the relation between ionospheric Pedersen conductance, its effect on the evolution and modification of field-aligned currents (FACs), and the influence of conductance and FACs on the formation of parallel electric fields which cause particle precipitation. Though the roles of ionospheric conductance gradients for FACs and parallel electric field evolution are directly related, they are poorly understood. This dissertation advances the understanding of these areas and all results of this study are based on numerical simulations that employ a three-dimensional - two-fluid (ions and neutrals) simulation code. The first part of this dissertation presents a systematic study of the magnetospheric and ionospheric influences on the evolution and modification of FACs with focus on the role of ionospheric Pedersen conductance and its gradients. FACs are typically generated in the magnetosphere and are carried into the ionosphere by Alfven waves. During their reflection from the ionosphere these FACs are modified depending on the magnitude and distribution of ionospheric conductance. For conductance gradients along the polarization of the wave, strong Pedersen currents can be generated which in turn enhance the FAC as well. The second part of this dissertation addresses the properties and evolution of parallel electric fields in an attempt to better understand the formation of discrete auroral arcs in response to the evolution of FACs for predetermined ionospheric conductance patterns. Frequently, auroral acceleration is believed to occur through U or V shaped potentials. Therefore, this part examines the properties of localized parallel electric fields in a uniform magnetic field. It is demonstrated that localized parallel electric fields generate magnetic flux in the absence of source of free energy. It is also shown that parallel

  13. Contactless Inductive Bubble Detection in a Liquid Metal Flow.

    PubMed

    Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

    2016-01-06

    The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy.

  14. Contactless Inductive Bubble Detection in a Liquid Metal Flow

    PubMed Central

    Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

    2016-01-01

    The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. PMID:26751444

  15. Unconstrained and contactless hand geometry biometrics.

    PubMed

    de-Santos-Sierra, Alberto; Sánchez-Ávila, Carmen; Del Pozo, Gonzalo Bailador; Guerra-Casanova, Javier

    2011-01-01

    This paper presents a hand biometric system for contact-less, platform-free scenarios, proposing innovative methods in feature extraction, template creation and template matching. The evaluation of the proposed method considers both the use of three contact-less publicly available hand databases, and the comparison of the performance to two competitive pattern recognition techniques existing in literature: namely support vector machines (SVM) and k-nearest neighbour (k-NN). Results highlight the fact that the proposed method outcomes existing approaches in literature in terms of computational cost, accuracy in human identification, number of extracted features and number of samples for template creation. The proposed method is a suitable solution for human identification in contact-less scenarios based on hand biometrics, providing a feasible solution to devices with limited hardware requirements like mobile devices.

  16. Unconstrained and Contactless Hand Geometry Biometrics

    PubMed Central

    de-Santos-Sierra, Alberto; Sánchez-Ávila, Carmen; del Pozo, Gonzalo Bailador; Guerra-Casanova, Javier

    2011-01-01

    This paper presents a hand biometric system for contact-less, platform-free scenarios, proposing innovative methods in feature extraction, template creation and template matching. The evaluation of the proposed method considers both the use of three contact-less publicly available hand databases, and the comparison of the performance to two competitive pattern recognition techniques existing in literature: namely Support Vector Machines (SVM) and k-Nearest Neighbour (k-NN). Results highlight the fact that the proposed method outcomes existing approaches in literature in terms of computational cost, accuracy in human identification, number of extracted features and number of samples for template creation. The proposed method is a suitable solution for human identification in contact-less scenarios based on hand biometrics, providing a feasible solution to devices with limited hardware requirements like mobile devices. PMID:22346634

  17. Active control of near-field coupling in conductively coupled microelectromechanical system metamaterial devices

    NASA Astrophysics Data System (ADS)

    Pitchappa, Prakash; Manjappa, Manukumara; Ho, Chong Pei; Qian, You; Singh, Ranjan; Singh, Navab; Lee, Chengkuo

    2016-03-01

    We experimentally report a structurally reconfigurable metamaterial for active switching of near-field coupling in conductively coupled, orthogonally twisted split ring resonators (SRRs) operating in the terahertz spectral region. Out-of-plane reconfigurable microcantilevers integrated into the dark SRR geometry are used to provide active frequency tuning of dark SRR resonance. The geometrical parameters of individual SRRs are designed to have identical inductive-capacitive resonant frequency. This allows for the excitation of classical analogue of electromagnetically induced transparency (EIT) due to the strong conductive coupling between the SRRs. When the microcantilevers are curved up, the resonant frequency of dark SRR blue-shifts and the EIT peak is completely modulated while the SRRs are still conductively connected. EIT modulation contrast of ˜50% is experimentally achieved with actively switchable group delay of ˜2.5 ps. Electrical control, miniaturized size, and readily integrable fabrication process of the proposed structurally reconfigurable metamaterial make it an ideal candidate for the realization of various terahertz communication devices such as electrically controllable terahertz delay lines, buffers, and tunable data-rate channels.

  18. Contactless microfluidic pumping using microchannel-integrated carbon black composite membranes

    PubMed Central

    Fu, Xiaotong; Gagnon, Zachary

    2015-01-01

    The ability to pump and manipulate fluid at the micron-scale is a basic requirement for microfluidic platforms. Many current manipulation methods, however, require expensive and bulky external supporting equipment, which are not typically compatible for portable applications. We have developed a contactless metal electro-osmotic micropump capable of pumping conductive buffers. The pump operates using two pairs of gallium metal electrodes, which are activated using an external voltage source and separated from a main flow channel by a thin micron-scale polydimethylsiloxane (PDMS) membrane. The thin contactless membrane allows for field penetration and electro-osmotic flow within the microchannel, but eliminates electrode damage and sample contamination commonly associated with traditional DC electro-osmotic pumps that utilize electrodes in direct contact with the working fluid. Our previous work has demonstrated the effectiveness of this method in pumping deionized water. However, due to the high resistivity of PDMS, this method proved difficult to apply towards manipulating conductive buffers. To overcome this limitation, we fabricated conductive carbon black (CB) powder directly into the contactless PDMS membranes. The increased electrical conductivity of the contactless PDMS membrane significantly increased micropump performance. Using a microfluidic T-channel device and an electro-osmotic flow model, we determined the influence that CB has on pump pressure for CB weight percents varying between 0 and 20. The results demonstrate that the CB increases pump pressure by two orders of magnitude and enables effective operations with conductive buffers. PMID:26543514

  19. Analysis of inorganic cations in biological samples by the combination of micro-electrodialysis and capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Doan, Thi Kieu Oanh; Kubáň, Pavel; Kubáň, Petr; Kiplagat, Isaac K; Boček, Petr

    2011-02-01

    Micro-electrodialysis (μED) and CE were combined for rapid pretreatment and subsequent determination of inorganic cations in biological samples. Combination of μED with CE greatly improved the analytical performance of the latter as the adsorption of high molecular weight compounds present in real samples on the inner capillary wall was eliminated. Fifty microliter of 80-fold diluted human body fluids such as plasma, serum and whole blood was used in the donor compartment of the μED system requiring less than 1 μL of the original body fluid per analysis. Inorganic cations that migrated through a cellulose acetate dialysis membrane with molecular weight cut-off value of 500 Da were collected in the acceptor solution and were then analyzed using CE-C⁴D. Baseline separation of inorganic cations was achieved in a BGE solution consisting of 12.5 mM maleic acid, 15 mM L-arginine and 3 mM 18-crown-6 at pH 5.5. Repeatability of the CE-C⁴D method was better than 0.5% and 2.5% for migration times and peak areas, respectively; limits of detection of all inorganic cations in the presence of 2 mM excess of Na(+) were around 1 μM and calibration curves were linear with correlation coefficients better than 0.998. Repeatability of the sample pretreatment procedure was calculated for six independent electrodialysis runs of artificial and real samples and was better than 11.8%. Recovery values between 96.3 and 110% were achieved for optimized electrodialysis conditions of standard solutions and real samples; lifetime of the dialysis membranes for pretreatment of real samples was estimated to 100 runs. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Local mapping of interface traps using contactless capacitance transient technique

    NASA Astrophysics Data System (ADS)

    Yoshida, Haruhiko; Mori, Hidenobu

    2016-10-01

    Contactless capacitance transient techniques have been applied to local mapping of interface traps of a semiconductor wafer. In contactless capacitance transient techniques, a Metal-Air gap-Oxide-Semiconductor (MAOS) structure is used instead of a conventional Metal-Oxide-Semiconductor (MOS) structure. The local mapping of interface traps was obtained by using a contactless Isothermal Capacitance Transient Spectroscopy (ICTS), which is one of the contactless capacitance transient techniques. The validity of the contactless ICTS was demonstrated by characterizing a partially Au-doped Si wafer. The results revealed that local mapping of interface traps using contactless capacitance transient techniques is effective in wafer inspection and is a promising technique for the development of MOS devices and solar cells with high reliability and high performance.

  1. Design and construction of a contactless mobile RF coil for double resonance variable angle spinning NMR.

    PubMed

    Qian, Chunqi; Pines, Alex; Martin, Rachel W

    2007-09-01

    Variable angle spinning (VAS) experiments can be used to measure long-range dipolar couplings and provide structural information about molecules in oriented media. We present a probe design for this type of experiment using a contactless resonator. In this circuit, RF power is transmitted wirelessly via coaxial capacitive coupling where the coupling efficiency is improved by replacing the ordinary sample coil with a double frequency resonator. Our probe constructed out of this design principle has shown favorable properties at variable angle conditions. Moreover, a switched angle spinning correlation experiment is performed to demonstrate the probe's capability to resolve dipolar couplings in strongly aligned molecules.

  2. Electric field enhanced conductivity in strongly coupled dense metal plasma

    SciTech Connect

    Stephens, J.; Neuber, A.

    2012-06-15

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field ({approx}6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  3. Electric field enhanced conductivity in strongly coupled dense metal plasma

    NASA Astrophysics Data System (ADS)

    Stephens, J.; Neuber, A.

    2012-06-01

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field (˜6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  4. Contactless electronic transport in a bio-molecular junction

    SciTech Connect

    Hossain, Faruque M. Al-Dirini, Feras; Skafidas, Efstratios

    2014-07-28

    Molecular electronics hold promise for next generation ultra-low power, nano-scale integrated electronics. The main challenge in molecular electronics is to make a reliable interface between molecules and metal electrodes. Interfacing metals and molecules detrimentally affects the characteristics of nano-scale molecular electronic devices. It is therefore essential to investigate alternative arrangements such as contact-less tunneling gaps wherever such configurations are feasible. We conduct ab initio density functional theory and non-equilibrium Green's functions calculations to investigate the transport properties of a biocompatible glycine molecular junction. By analyzing the localized molecular orbital energy distributions and transmission probabilities in the transport-gap, we find a glycine molecule confined between two gold electrodes, without making a contact, is energetically stable and possesses high tunneling current resembling an excellent ohmic-like interface.

  5. Serpentine Thermal Coupling Between a Stream and a Conducting Body

    SciTech Connect

    Kobayashi, H.; Lorente, S.; Anderson, R.; Bejan, A.

    2012-02-15

    Here we document the effect of flow configuration on the heat transfer performance of a serpentine shaped stream embedded in a conducting solid. Several configurations with fixed volume of fluid are considered: U-shaped with varying spacing between the parallel portions of the U, serpentine shapes with three elbows, and conducting soil with several parallelepipedal shapes. We show that the spacing must be greater than a critical value in order for the heat transfer density of the stream-solid configuration to be the highest that it can be. Spacings larger than this critical value do not yield improvements in heat transfer density. We also show that even though the heat transfer is time dependent, the stream-solid configuration has an effective number of heat transfer units Ntu that is nearly constant in time. The larger Ntu values correspond to the configurations with greater heat transfer density.

  6. Thermal rectification and negative differential thermal conductance in harmonic chains with nonlinear system-bath coupling

    NASA Astrophysics Data System (ADS)

    Ming, Yi; Li, Hui-Min; Ding, Ze-Jun

    2016-03-01

    Thermal rectification and negative differential thermal conductance were realized in harmonic chains in this work. We used the generalized Caldeira-Leggett model to study the heat flow. In contrast to most previous studies considering only the linear system-bath coupling, we considered the nonlinear system-bath coupling based on recent experiment [Eichler et al., Nat. Nanotech. 6, 339 (2011), 10.1038/nnano.2011.71]. When the linear coupling constant is weak, the multiphonon processes induced by the nonlinear coupling allow more phonons transport across the system-bath interface and hence the heat current is enhanced. Consequently, thermal rectification and negative differential thermal conductance are achieved when the nonlinear couplings are asymmetric. However, when the linear coupling constant is strong, the umklapp processes dominate the multiphonon processes. Nonlinear coupling suppresses the heat current. Thermal rectification is also achieved. But the direction of rectification is reversed compared to the results of weak linear coupling constant.

  7. Contactless method of measuring resistivity

    NASA Technical Reports Server (NTRS)

    Crowley, J. D.; Rabson, T. A.

    1976-01-01

    A method is described for measuring the conductivity of materials without having to make electrical contact with the material. Currents which are magnetically induced in the conducting sample are measured by means of the magnetic fields they produce. Although induction techniques have been used in the past for this type of measurement, the configuration presented here makes it possible to perform absolute measurements of resistivity over a wide range of values for relatively small samples. The theory of the technique, the results of measurements made with it, and a comparison of the technique with other methods are presented.

  8. Contactless Investigations of Yeast Cell Cultivation in the 7 GHz and 240 GHz Ranges

    NASA Astrophysics Data System (ADS)

    Wessel, J.; Schmalz, K.; Gastrock, G.; Cahill, B. P.; Meliani, C.

    2013-04-01

    Using a microfluidic system based on PTFE tubes, experimental results of contactless and label-free characterization techniques of yeast cell cultivation are presented. The PTFE tube has an inner diameter of 0.5 mm resulting in a sample volume of 2 μ1 for 1 cm sample length. Two approaches (at frequencies around 7 GHz and 240 GHz) are presented and compared in terms of sensitivity and applicability. These frequency bands are particularly interesting to gain information on the permittivity of yeast cells in Glucose solution. Measurements from 240 GHz to 300 GHz were conducted with a continuous wave spectrometer from Toptica. At 7 GHz band, measurements have been performed using a rat-race based characterizing system realized on a printed circuit board. The conducted experiments demonstrate that by selecting the phase as characterization parameter, the presented contactless and label-free techniques are suitable for cell cultivation monitoring in a PTFE pipe based microfluidic system.

  9. Toward Contactless Biology: Acoustophoretic DNA Transfection

    PubMed Central

    Vasileiou, Thomas; Foresti, Daniele; Bayram, Adem; Poulikakos, Dimos; Ferrari, Aldo

    2016-01-01

    Acoustophoresis revolutionized the field of container-less manipulation of liquids and solids by enabling mixing procedures which avoid contamination and loss of reagents due to the contact with the support. While its applications to chemistry and engineering are straightforward, additional developments are needed to obtain reliable biological protocols in a contactless environment. Here, we provide a first, fundamental step towards biological reactions in air by demonstrating the acoustophoretic DNA transfection of mammalian cells. We developed an original acoustophoretic design capable of levitating, moving and mixing biological suspensions of living mammalians cells and of DNA plasmids. The precise and sequential delivery of the mixed solutions into tissue culture plates is actuated by a novel mechanism based on the controlled actuation of the acoustophoretic force. The viability of the contactless procedure is tested using a cellular model sensitive to small perturbation of neuronal differentiation pathways. Additionally, the efficiency of the transfection procedure is compared to standard, container-based methods for both single and double DNA transfection and for different cell types including adherent growing HeLa cancer cells, and low adhesion neuron-like PC12 cells. In all, this work provides a proof of principle which paves the way to the development of high-throughput acoustophoretic biological reactors. PMID:26828312

  10. Toward Contactless Biology: Acoustophoretic DNA Transfection

    NASA Astrophysics Data System (ADS)

    Vasileiou, Thomas; Foresti, Daniele; Bayram, Adem; Poulikakos, Dimos; Ferrari, Aldo

    2016-02-01

    Acoustophoresis revolutionized the field of container-less manipulation of liquids and solids by enabling mixing procedures which avoid contamination and loss of reagents due to the contact with the support. While its applications to chemistry and engineering are straightforward, additional developments are needed to obtain reliable biological protocols in a contactless environment. Here, we provide a first, fundamental step towards biological reactions in air by demonstrating the acoustophoretic DNA transfection of mammalian cells. We developed an original acoustophoretic design capable of levitating, moving and mixing biological suspensions of living mammalians cells and of DNA plasmids. The precise and sequential delivery of the mixed solutions into tissue culture plates is actuated by a novel mechanism based on the controlled actuation of the acoustophoretic force. The viability of the contactless procedure is tested using a cellular model sensitive to small perturbation of neuronal differentiation pathways. Additionally, the efficiency of the transfection procedure is compared to standard, container-based methods for both single and double DNA transfection and for different cell types including adherent growing HeLa cancer cells, and low adhesion neuron-like PC12 cells. In all, this work provides a proof of principle which paves the way to the development of high-throughput acoustophoretic biological reactors.

  11. Real-time monitoring of strand-displacement DNA amplification by a contactless electrochemical microsystem using interdigitated electrodes.

    PubMed

    Fang, Xinxin; Zhang, Huanqian; Zhang, Feng; Jing, Fengxiang; Mao, Hongju; Jin, Qinghui; Zhao, Jianlong

    2012-09-07

    This paper reports the design and implementation of a contactless conductivity detection system which combines a thermal control cell, a data processing system and an electrochemical (EC) cell for label-free isothermal nucleic acid amplification and real-time monitoring. The EC cell consists of a microchamber and interdigitated electrodes as the contactless conductivity biosensor with a cover slip as insulation. In our work, contactless EC measurements, the effects of trehalose on amplification, and chip surface treatment are investigated. With the superior performance of the biosensor, the device can detect the amount of pure DNA at concentrations less than 0.1 pg μl(-1). The EC cell, integrated with a heater and a temperature sensor, has successfully implemented nicking-based strand-displacement amplification at an initial concentration of 2.5 μM and the yields are monitored directly (dismissing the use of probes or labels) on-line. This contactless detector carries important advantages: high anti-interference capability, long detector life, high reusability and low cost. In addition, the small size, low power consumption and portability of the detection cell give the system the potential to be highly integrated for use in field service and point of care applications.

  12. Thermal conductance of a two-level atom coupled to two quantum harmonic oscillators

    NASA Astrophysics Data System (ADS)

    Guimarães, Pedro H.; Landi, Gabriel T.; de Oliveira, Mário J.

    2017-04-01

    We have determined the thermal conductance of a system consisting of a two-level atom coupled to two quantum harmonic oscillators in contact with heat reservoirs at distinct temperatures. The calculation of the heat flux as well as the atomic population and the rate of entropy production are obtained by the use of a quantum Fokker-Planck-Kramers equation and by a Lindblad master equation. The calculations are performed for small values of the coupling constant. The results coming from both approaches show that the conductance is proportional to the coupling constant squared and that, at high temperatures, it is proportional to the inverse of temperature.

  13. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Lapas, Panteleimon; Stamokostas, Georgios; Fiete, Gregory

    2015-03-01

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  14. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  15. Vibration analysis using a contactless acquisition system

    NASA Astrophysics Data System (ADS)

    Catalano, Pasquale; Fucci, Flavio; Giametta, Ferruccio; La Fianza, Giovanna; Bianchi, Biagio

    2013-05-01

    The problem of vibration measurement has assumed increasing importance in recent years for different aspects. In the first phase of this study an analysis of vibrations by means of contact accelerometers was carried out to study a tree shaking machine used in the mechanical harvesting of olives. Then a kinematic analysis of motion with a contactless method was carried out on a belt transmission system equipped with three pulleys: a high speed camera was used, able to capture up to 500 frames per second thus to follow the position of any moving point of the mechanical system under investigation. Vibrations were acquired detecting the positions during time of a marker fixed on the belt. The proposed method made it possible to analyse the mechanism and verify both known behaviours and neglected aspects in the usual kinematic analysis carried out using acceleration measurements.

  16. [Modeling and analysis of volume conduction based on field-circuit coupling].

    PubMed

    Tang, Zhide; Liu, Hailong; Xie, Xiaohui; Chen, Xiufa; Hou, Deming

    2012-08-01

    Numerical simulations of volume conduction can be used to analyze the process of energy transfer and explore the effects of some physical factors on energy transfer efficiency. We analyzed the 3D quasi-static electric field by the finite element method, and developed A 3D coupled field-circuit model of volume conduction basing on the coupling between the circuit and the electric field. The model includes a circuit simulation of the volume conduction to provide direct theoretical guidance for energy transfer optimization design. A field-circuit coupling model with circular cylinder electrodes was established on the platform of the software FEM3.5. Based on this, the effects of electrode cross section area, electrode distance and circuit parameters on the performance of volume conduction system were obtained, which provided a basis for optimized design of energy transfer efficiency.

  17. Contactless dielectrophoresis: a new technique for cell manipulation.

    PubMed

    Shafiee, Hadi; Caldwell, John L; Sano, Michael B; Davalos, Rafael V

    2009-10-01

    Dielectrophoresis (DEP) has become a promising technique to separate and identify cells and microparticles suspended in a medium based on their size or electrical properties. Presented herein is a new technique to provide the non-uniform electric field required for DEP that does not require electrodes to contact the sample fluid. In our method, electrodes are capacitively-coupled to a fluidic channel through dielectric barriers; the application of a high-frequency electric field to these electrodes then induces an electric field in the channel. This technique combines the cell manipulation abilities of traditional DEP with the ease of fabrication found in insulator-based technologies. A microfluidic device was fabricated based on this principle to determine the feasibility of cell manipulations through contactless DEP (cDEP). We were able to demonstrate cell responses unique to the DEP effect in three separate cell lines. These results illustrate the potential for this technique to identify cells through their electrical properties without fear of contamination from electrodes.

  18. Contactless thin adaptive mirror technology: past, present, and future

    NASA Astrophysics Data System (ADS)

    Biasi, Roberto; Gallieni, Daniele; Salinari, Piero; Riccardi, Armando; Mantegazza, Paolo

    2010-07-01

    The contactless, voice coil motor adaptive mirror technology starts from an idea by Piero Salinari in 1993. This idea has progressively evolved to real systems thanks to a fruitful collaboration involving Italian research institutes (INAF - Osservatorio Astrofisico di Arcetri and Aerospace Department of Politecnico di Milano) and small Italian enterprises (Microgate and ADS). Collaboration between research institutions and industry is still very effectively in place, but nowadays the technology has left the initial R&D phase reaching a stage in which the whole projects are managed by the industrial entities. In this paper we present the baseline concept and its evolution, describing the main progress milestones. These are paced by the actual implementation of this idea into real systems, from MMT, to LBT, Magellan, VLT, GMT and E-ELT. The fundamental concept and layout has remained unchanged through this evolution, maintaining its intrinsic advantages: tolerance to actuators' failures, mechanical de-coupling and relaxed tolerances between correcting mirror and reference structure, large stroke, hysteresis-free behavior. Moreover, this concept has proved its expandability to very large systems with thousands of controlled d.o.f. Notwithstanding the solidity of the fundamentals, the implementation has strongly evolved from the beginning, in order to deal with the dimensional, power, maintainability and reliability constraints imposed by the increased size of the targeted systems.

  19. Effects of heterogeneity in synaptic conductance between weakly coupled identical neurons.

    PubMed

    Bradley, Patrick J; Wiesenfeld, Kurt; Butera, Robert J

    2011-04-01

    A significant degree of heterogeneity in synaptic conductance is present in neuron to neuron connections. We study the dynamics of weakly coupled pairs of neurons with heterogeneities in synaptic conductance using Wang-Buzsaki and Hodgkin-Huxley model neurons which have Types I and II excitability, respectively. This type of heterogeneity breaks a symmetry in the bifurcation diagrams of equilibrium phase difference versus the synaptic rate constant when compared to the identical case. For weakly coupled neurons coupled with identical values of synaptic conductance a phase locked solution exists for all values of the synaptic rate constant, α. In particular, in-phase and anti-phase solutions are guaranteed to exist for all α. Heterogeneity in synaptic conductance results in regions where no phase locked solution exists and the general loss of the ubiquitous in-phase and anti-phase solutions of the identically coupled case. We explain these results through examination of interaction functions using the weak coupling approximation and an in-depth analysis of the underlying multiple cusp bifurcation structure of the systems of coupled neurons.

  20. Effects of heterogeneity in synaptic conductance between weakly coupled identical neurons

    PubMed Central

    Bradley, Patrick; Wiesenfeld, Kurt; Butera, Robert

    2010-01-01

    A significant degree of heterogeneity in synaptic conductance is present in neuron to neuron connections. We study the dynamics of weakly coupled pairs of neurons with heterogeneities in synaptic conductance using Wang-Buzsaki and Hodgkin-Huxley model neurons which have Type I and Type II excitability, respectively. This type of heterogeneity breaks a symmetry in the bifurcation diagrams of equilibrium phase difference versus the synaptic rate constant when compared to the identical case. For weakly coupled neurons coupled with identical values of synaptic conductance a phase locked solution exists for all values of the synaptic rate constant, α. In particular, in-phase and anti-phase solutions are guaranteed to exist for all α. Heterogeneity in synaptic conductance results in regions where no phase locked solution exists and the general loss of the ubiquitous in-phase and anti-phase solutions of the identically coupled case. We explain these results through examination of interaction functions using the weak coupling approximation and an in depth analysis of the underlying multiple cusp bifurcation structure of the systems of coupled neurons. PMID:20799058

  1. Molar conductivity calculation of Li-ion battery electrolyte based on mode coupling theory

    NASA Astrophysics Data System (ADS)

    Pu, Weihua; He, Xiangming; Lu, Jiufang; Jiang, Changyin; Wan, Chunrong

    2005-12-01

    A method is proposed to calculate molar conductivity based on mode coupling theory in which the ion transference number is introduced into the theory. The molar conductivities of LiPF6, LiClO4, LiBF4, LiAsF6 in PC (propylene carbonate) are calculated based on this method. The results fit well to the literature data. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes.

  2. Molar conductivity calculation of Li-ion battery electrolyte based on mode coupling theory.

    PubMed

    Pu, Weihua; He, Xiangming; Lu, Jiufang; Jiang, Changyin; Wan, Chunrong

    2005-12-15

    A method is proposed to calculate molar conductivity based on mode coupling theory in which the ion transference number is introduced into the theory. The molar conductivities of LiPF6, LiClO4, LiBF4, LiAsF6 in PC (propylene carbonate) are calculated based on this method. The results fit well to the literature data. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes.

  3. Conduction of feedback-mediated signal in a computational model of coupled nephrons.

    PubMed

    Sgouralis, Ioannis; Layton, Anita T

    2016-03-01

    The nephron in the kidney regulates its fluid flow by several autoregulatory mechanisms. Two primary mechanisms are the myogenic response and the tubuloglomerular feedback (TGF). The myogenic response is a property of the pre-glomerular vasculature in which a rise in intravascular pressure elicits vasoconstriction that generates a compensatory increase in vascular resistance. TGF is a negative feedback response that balances glomerular filtration with tubular reabsorptive capacity. While each nephron has its own autoregulatory response, the responses of the kidney's many nephrons do not act autonomously but are instead coupled through the pre-glomerular vasculature. To better understand the conduction of these signals along the pre-glomerular arterioles and the impacts of internephron coupling on nephron flow dynamics, we developed a mathematical model of renal haemodynamics of two neighbouring nephrons that are coupled in that their afferent arterioles arise from a common cortical radial artery. Simulations were conducted to estimate internephron coupling strength, determine its dependence on vascular properties and to investigate the effect of coupling on TGF-mediated flow oscillations. Simulation results suggest that reduced gap-junctional conductances may yield stronger internephron TGF coupling and highly irregular TGF-mediated oscillations in nephron dynamics, both of which experimentally have been associated with hypertensive rats. © The Authors 2015. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  4. Conduction of feedback-mediated signal in a computational model of coupled nephrons

    PubMed Central

    Sgouralis, Ioannis; Layton, Anita T.

    2016-01-01

    The nephron in the kidney regulates its fluid flow by several autoregulatory mechanisms. Two primary mechanisms are the myogenic response and the tubuloglomerular feedback (TGF). The myogenic response is a property of the pre-glomerular vasculature in which a rise in intravascular pressure elicits vasoconstriction that generates a compensatory increase in vascular resistance. TGF is a negative feedback response that balances glomerular filtration with tubular reabsorptive capacity. While each nephron has its own autoregulatory response, the responses of the kidney's many nephrons do not act autonomously but are instead coupled through the pre-glomerular vasculature. To better understand the conduction of these signals along the pre-glomerular arterioles and the impacts of internephron coupling on nephron flow dynamics, we developed a mathematical model of renal haemodynamics of two neighbouring nephrons that are coupled in that their afferent arterioles arise from a common cortical radial artery. Simulations were conducted to estimate internephron coupling strength, determine its dependence on vascular properties and to investigate the effect of coupling on TGF-mediated flow oscillations. Simulation results suggest that reduced gap-junctional conductances may yield stronger internephron TGF coupling and highly irregular TGF-mediated oscillations in nephron dynamics, both of which experimentally have been associated with hypertensive rats. PMID:25795767

  5. The dual effect of ephaptic coupling on cardiac conduction with heterogeneous expression of connexin 43.

    PubMed

    Wei, Ning; Mori, Yoichiro; Tolkacheva, Elena G

    2016-05-21

    Decreased and heterogeneous expression of connexin 43 (Cx43) are common features in animal heart failure models. Ephpatic coupling, which relies on the presence of junctional cleft space between the ends of adjacent cells, has been suggested to play a more active role in mediating intercellular electrical communication when gap junctions are reduced. To better understand the interplay of Cx43 expression and ephaptic coupling on cardiac conduction during heart failure, we performed numerical simulations on our model when Cx43 expression is reduced and heterogeneous. Under severely reduced Cx43 expression, we identified three new phenomena in the presence of ephaptic coupling: alternating conduction, in which ephaptic and gap junction-mediated mechanisms alternate; instability of planar fronts; and small amplitude action potential (SAP), which has a smaller potential amplitude than the normal action potential. In the presence of heterogeneous Cx43 expression, ephaptic coupling can either prevent or promote conduction block (CB) depending on the Cx43 knockout (Cx43KO) content. When Cx43KO content is relatively high, ephaptic coupling reduces the probabilities of CB. However, ephaptic coupling promotes CB when Cx43KO and wild type cells are mixed in roughly equal proportion, which can be attributed to an increase in current-to-load mismatch.

  6. Energy conserving coupling through small apertures in an infinite perfect conducting screen

    NASA Astrophysics Data System (ADS)

    Petzold, J.; Tkachenko, S.; Vick, R.

    2015-11-01

    Apertures in shielding enclosures are an important issue for determining shielding efficiencies. Various mathematical procedures and theories were employed to describe the coupling between the regions connected via an aperture in a well conducting plane. Bethe's theory describes the coupling via the equivalent problem of field excited dipole moments at the location of the aperture. This approach neglects the reaction of the dipole moments on the exciting field and therefore violates energy conservation. This work emphasizes an analytical approach for coupling between half-spaces through small apertures, inspired by the so called method of small antenna, which allows an understandable generalization of Bethe's theory.

  7. Thermal conductance of electrons in graphene and stanene ribbons modulated via electron-phonon coupling

    NASA Astrophysics Data System (ADS)

    Peng, Xiao-Fang; Zhou, Xin; Jiang, Xiang-Tao; Gao, Ren-Bin; Tan, Shi-Hua; Chen, Ke-Qiu

    2017-08-01

    The thermal transport properties of the electrons in stanene nanoribbons (SNRs) and graphene nanoribbons (GNRs) are studied using a nonequilibrium Green's function approach in which the effects of electron-phonon coupling are considered. The results demonstrate that the electron thermal conductance values in both SNRs and GNRs are closely related to both the temperature T and the chemical potential μ. Comparison with the thermal transport properties of GNRs shows that the quantized thermal conductance plateau in SNRs is narrower at low temperatures, while the thermal conductance is also greater at higher temperatures in SNRs. The periodic strain-induced electron-phonon coupling can modulate the thermal conductance periodically in both SNRs and GNRs.

  8. Synergistic plasticity of intrinsic conductance and electrical coupling restores synchrony in an intact motor network.

    PubMed

    Lane, Brian J; Samarth, Pranit; Ransdell, Joseph L; Nair, Satish S; Schulz, David J

    2016-08-23

    Motor neurons of the crustacean cardiac ganglion generate virtually identical, synchronized output despite the fact that each neuron uses distinct conductance magnitudes. As a result of this variability, manipulations that target ionic conductances have distinct effects on neurons within the same ganglion, disrupting synchronized motor neuron output that is necessary for proper cardiac function. We hypothesized that robustness in network output is accomplished via plasticity that counters such destabilizing influences. By blocking high-threshold K(+) conductances in motor neurons within the ongoing cardiac network, we discovered that compensation both resynchronized the network and helped restore excitability. Using model findings to guide experimentation, we determined that compensatory increases of both GA and electrical coupling restored function in the network. This is one of the first direct demonstrations of the physiological regulation of coupling conductance in a compensatory context, and of synergistic plasticity across cell- and network-level mechanisms in the restoration of output.

  9. Contactless Magnetic Gear for Robot Control Application

    NASA Astrophysics Data System (ADS)

    Komiyama, Hiroki; Uchimura, Yutaka

    This paper describes the application of a magnetic gear to a robot by fulfilling the essential requirements for a robot control, which are velocity control, position control, and force control. A magnetic gear is a transmission device that realizes contactless torque transmission by applying a magnetic force. When using a magnetic gear, cogging torque and spring characteristics need to be considered. In this paper, we introduce an approximate model of cogging torque. This model is used for velocity control to attenuate the disturbance due to cogging torque. In the case of position control, the oscillations due to the spring effect of the magnetic attractive force become a problem. To reduce the adverse effect due to these oscillations, resonance ratio control is applied. We also propose to use a magnetic gear for realizing the force sensorless bilateral control of teleoperation. Thanks to the frictionless transmission of a magnetic gear, the force sensorless estimation of a reaction force can be realized using a reaction force observer.

  10. Contactless sub-millimeter displacement measurements

    NASA Astrophysics Data System (ADS)

    Sliepen, Guus; Jägers, Aswin P. L.; Bettonvil, Felix C. M.; Hammerschlag, Robert H.

    2008-07-01

    Weather effects on foldable domes, as used at the DOT and GREGOR, are investigated, in particular the correlation between the wind field and the stresses caused to both metal framework and tent clothing. Camera systems measure contactless the displacement of several dome points. The stresses follow from the measured deformation pattern. The cameras placed near the dome floor do not disturb telescope operations. In the set-ups of DOT and GREGOR, these cameras are up to 8 meters away from the measured points and must be able to detect displacements of less than 0.1 mm. The cameras have a FireWire (IEEE1394) interface to eliminate the need for frame grabbers. Each camera captures 15 images of 640 × 480 pixels per second. All data is processed on-site in real-time. In order to get the best estimate for the displacement within the constraints of available processing power, all image processing is done in Fourier-space, with all convolution operations being pre-computed once. A sub-pixel estimate of the peak of the correlation function is made. This enables to process the images of four cameras using only one commodity PC with a dual-core processor, and achieve an effective sensitivity of up to 0.01 mm. The deformation measurements are well correlated to the simultaneous wind measurements. The results are of high interest to upscaling the dome design (ELTs and solar telescopes).

  11. Multiscale development of a fission gas thermal conductivity model: Coupling atomic, meso and continuum level simulations

    NASA Astrophysics Data System (ADS)

    Tonks, Michael R.; Millett, Paul C.; Nerikar, Pankaj; Du, Shiyu; Andersson, David; Stanek, Christopher R.; Gaston, Derek; Andrs, David; Williamson, Richard

    2013-09-01

    Fission gas production and evolution significantly impact the fuel performance, causing swelling, a reduction in the thermal conductivity and fission gas release. However, typical empirical models of fuel properties treat each of these effects separately and uncoupled. Here, we couple a fission gas release model to a model of the impact of fission gas on the fuel thermal conductivity. To quantify the specific impact of grain boundary (GB) bubbles on the thermal conductivity, we use atomistic and mesoscale simulations. Atomistic molecular dynamic simulations were employed to determine the GB thermal resistance. These values were then used in mesoscale heat conduction simulations to develop a mechanistic expression for the effective GB thermal resistance of a GB containing gas bubbles, as a function of the percentage of the GB covered by fission gas. The coupled fission gas release and thermal conductivity model was implemented in Idaho National Laboratory's BISON fuel performance code to model the behavior of a 10-pellet LWR fuel rodlet, showing how the fission gas impacts the UO2 thermal conductivity. Furthermore, additional BISON simulations were conducted to demonstrate the impact of average grain size on both the fuel thermal conductivity and the fission gas release.

  12. Giant conductance anisotropy in magnetically coupled ferromagnet-superconductor-ferromagnet structures.

    SciTech Connect

    Belkin, A.; Novosad, V.; Iavarone, M.; Divan, R.; Hiller, J.; Proslier, T.; Pearson, J. E.; Karapetrov, G.; Illinois Inst. of Tech.; Temple Univ.

    2010-01-01

    We demonstrate the evolution of the anisotropic conductivity in the superconductor that is magnetically coupled with two adjacent ferromagnetic layers. Stripe magnetic domain structure in the ferromagnetic layers results in directional superconducting order parameter in the superconducting layer. The conductance anisotropy strongly depends on the period of the magnetic domains and the strength of the local magnetization. The anisotropic conductivity of up to three orders of magnitude can be achieved with spatial critical temperature modulation of 5% of T{sub c}. The effect could be exploited in low temperature nonvolatile logic and storage elements.

  13. Molecular Dynamics Simulations of Shocks Including Electronic Heat Conduction and Electron-Phonon Coupling

    NASA Astrophysics Data System (ADS)

    Ivanov, Dmitriy S.; Zhigilei, Leonid V.; Bringa, Eduardo M.; De Koning, Maurice; Remington, Bruce A.; Caturla, Maria Jose; Pollaine, Stephen M.

    2004-07-01

    Shocks are often simulated using the classical molecular dynamics (MD) method in which the electrons are not included explicitly and the interatomic interaction is described by an effective potential. As a result, the fast electronic heat conduction in metals and the coupling between the lattice vibrations and the electronic degrees of freedom can not be represented. Under conditions of steep temperature gradients that can form near the shock front, however, the electronic heat conduction can play an important part in redistribution of the thermal energy in the shocked target. We present the first atomistic simulation of a shock propagation including the electronic heat conduction and electron-phonon coupling. The computational model is based on the two-temperature model (TTM) that describes the time evolution of the lattice and electron temperatures by two coupled non-linear differential equations. In the combined TTM-MD method, MD substitutes the TTM equation for the lattice temperature. Simulations are performed with both MD and TTM-MD models for an EAM Al target shocked at 300 kbar. The target includes a tilt grain boundary, which provides a region where shock heating is more pronounced and, therefore, the effect of the electronic heat conduction is expected to be more important. We find that the differences between the predictions of the MD and TTM-MD simulations are significantly smaller as compared to the hydrodynamics calculations performed at similar conditions with and without electronic heat conduction.

  14. Effects of Rashba spin-orbit coupling on the conductance of graphene-based nanoribbons

    NASA Astrophysics Data System (ADS)

    Rashidian, Zeinab; Bayati, Parvin; Lorestaniwiess, Zeinab

    2017-03-01

    The transmission properties of armchair- and zigzag-edged graphene nanoribbon junctions between graphene electrodes are examined by means of the standard nonequilibrium Green’s function (NEGF) technique. The quantum transport of electrons is studied through a monolayer graphene strip in the presence of Rashba spin-orbit coupling that acts as a barrier between the two normal leads. The present work compares the conductances of nanoribbons with zigzag and armchair edges. Since the nature of induced gap for zigzag edge is different from armchair, it is expected to give rise to different types of conductance for each edge. Findings indicate that the Rashba strength has more pronounced influence on armchair ribbons than on zigzag ribbons, and the minimum conductance of 2G0 for nanoribbon remains intact even in the presence of the Rashba spin-orbit coupling. It is predicted that controllability of spin transport in the monolayer graphene may contribute to the development of well-known spintronics.

  15. Programs EMCUPL and SCHCOPL: computation of electromagnetic coupling on a layered halfspace with complex conductivities

    USGS Publications Warehouse

    Kauahikaua, James P.; Anderson, Walter L.

    1979-01-01

    A number of efficient numerical computer algorithms are incorporated into a general program called EMCUPL, which calculates the electromagnetic (EM) coupling between two straight wires on the surface of a multilayered half space. Each layer has an isotropic conductivity which may be either real or complex. A second computer program, called SCHCOPL, is described which calculates the coupling for the special case of a Schlumberger or Wenner array also on a multilayered half space. Comparison with other programs shows that EMCUPL is at least as accurate, more generally applicable, and computationally more efficient FORTRAN listings of all subprograms and example calculations are given in the Appendix.

  16. Contactless laser bending of silicon microstructures

    NASA Astrophysics Data System (ADS)

    Exner, Horst; Loschner, Udo

    2003-04-01

    We are going to present a new technology for laser bending of silicon microstructures based upon a suggestion of and carried out in cooperation with Prof. Dr. J. Fr'hauf from the Technical University Chemnitz (see acknowledgement). We investigated the influence of various laser process parameters on the bending angle and its reproducibility. Bending of the silicon element as a result of the laser induced thermal stresses in the material occurs toward the incident laser beam. The bending angle depends on a lot of laser process and material parameters. In particular we found that the irra-diation regime is well suited to control the bending angle. First substantial FEM based calculations of laser induced temperature fields using a moving laser heat source show the temperature field propagation in the material and reveal some regions of complicated overheating. As a result of our experiments we show a variety of examples including mul-tiple and also continuous bendings. There are several essential advantages compared to conventional bending technologies with this new method: Laser bending is contactless without using additional tools or external forces. Because of the local laser treatment the heat flux to the neighbouring material is minimized. The laser beam can be applied through windows of glass that means to al-most hermetically sealed micro devices. So laser technology is suitable for machining of already finished microsystems. It opens up a wide field of applications in micro system technologies: clip-chip-mechanism or sliding chips for micro optical benches, the adjustment of optical mirrors or other components or the ability of continuous bending for electro-static drives and so on.

  17. Contactless decontamination of hair samples: cannabinoids.

    PubMed

    Restolho, José; Barroso, Mário; Saramago, Benilde; Dias, Mário; Afonso, Carlos A M

    2017-02-01

    Room temperature ionic liquids (ILs) have already been shown to provide efficient extraction media for several systems, and to capture volatile compounds, namely opiates. In this work, a novel, contactless, artefact-free extraction procedure for the removal of Δ(9) -tetrahrydrocannabinol (THC) from the surface of human hair is presented. To prepare in vitro cannabinoids-contaminated hair, samples were flushed with hashish smoke for 7 h. The decontamination experiments were carried at 100 °C for 24 h, according to the procedure previously described. Fifty-three ILs were screened and presented decontamination efficiencies ranging from 0 to 96 %. Although the majority of the ILs presented efficiencies above 90%, the 1-ethanol-3-methyl tetrafluoroborate (96%) was chosen for further process optimization. The Design of Experiments results demonstrated that all studied variables were significant for the process and the obtained optimum conditions were: 100 °C, 13 h and 175 mg of IL. In the work of Perrotin-Brunel et al. (J. Mol. Struct. 2011, 987, 67), it is demonstrated that, at 100 °C, full conversion of tetrahydrocannabinolic acid (THCA) into THC is obtained after 60 min. Since our decontamination takes place over 13 h at 100 °C, full conversion of THCA into THC is expected. Additionally, our method was compared with the method proposed by Cairns et al. (Forensic Sci. Int. 2004, 145, 97), through the analysis of 15 in vitro contaminated hair samples. The results demonstrated that with our method a mean extraction efficiency of 11 % higher was obtained. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Resonant elements contactless coupled to bolometric micro-stripes

    NASA Astrophysics Data System (ADS)

    Cuadrado, Alexander; Silva-López, Manuel; López-Alonso, José M.; Martínez-Antón, Juan C.; Ezquerro, José M.; González, Francisco J.; Alda, Javier

    2015-08-01

    One of the main technical difficulties in the fabrication of optical antennas working as light detectors is the proper design and manufacture of auxiliary elements as load lines and signal extraction structures. These elements need to be quite small to reach the location of the antennas and should have a minimal effect on the response of the device. Unfortunately this is not an easy task and signal extraction lines resonate along with the antenna producing a complex signal that usually masks the one given by the antenna. In order to decouple the resonance from the transduction we present in this contribution a parametric analysis of the response of a bolometric stripe that is surrounded by resonant dipoles with different geometries and orientations. We have checked that these elements should provide a signal proportional to the polarization state of the incoming light.

  19. Three dimensional magnetism and coupling to conduction electrons in PdCrO2

    SciTech Connect

    Ong, Khuong P; Singh, David J

    2012-01-01

    We report density functional calculations addressing the electronic structure and magnetic properties of delafossite PdCrO{sub 2}. We find substantial magnetic interactions in the c-axis direction as well as beyond first nearest neighbors in-plane, so that PdCrO{sub 2} is a three-dimensional (3D) frustrated antiferromagnet. We also find substantial coupling between the Cr moments and the Pd derived conduction electrons.

  20. Meshless method for solving coupled radiative and conductive heat transfer in refractive index medium

    NASA Astrophysics Data System (ADS)

    Wang, Cheng-An; Sadat, Hamou; Tan, Jian-Yu

    2016-01-01

    A diffuse approximation meshless method (DAM) is employed as a means of solving the coupled radiative and conductive heat transfer problems in semi-transparent refractive index media contained in 1D and 2D geometries. The meshless approach for radiative transfer is based on the discrete ordinates equation. Cases of combined conduction- radiation are presented, including plane parallel slab, square enclosure, and semicircular enclosure with an inner circle. The influence of the refractive index on the temperature distributions and heat fluxes is investigated. Results obtained using the proposed meshless method are compared with those reported in the literature to demonstrate the flexibility and accuracy of the method.

  1. Coupled quantum wires as a detector of many-body states below the last conductance plateau.

    SciTech Connect

    Sasaki, T.; Lilly, Michael Patrick; Bird, J. P.; Shailos, A.; Reno, John Louis; Ochiai, Y.; Aoki, N.; Iwase, Y.; Morimoto, T.; Simmons, Jerry Alvon

    2004-03-01

    We demonstrate the presence of a resonant interaction between a pair of coupled quantum wires, which are realized in the ultra-high mobility two-dimensional electron gas of a GaAs/AlGaAs quantum well. Measuring the conductance of one wire, as the width of the other is varied, we observe a resonant peak in its conductance that is correlated with the point at which the swept wire pinches off. We discuss this behavior in terms of recent theoretical predictions concerning local spin-moment formation in quantum wires.

  2. Thermal conductivity of local moment models with strong spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Stamokostas, Georgios L.; Lapas, Panteleimon E.; Fiete, Gregory A.

    2017-02-01

    We study the magnetic and lattice contributions to the thermal conductivity of electrically insulating strongly spin-orbit coupled magnetically ordered phases on a two-dimensional honeycomb lattice using the Kitaev-Heisenberg model. Depending on model parameters, such as the relative strength of the spin-orbit induced anisotropic coupling, a number of magnetically ordered phases are possible. In this work, we study two distinct regimes of thermal transport depending on whether the characteristic energy of the phonons or the magnons dominates, and focus on two different relaxation mechanisms, boundary scattering and magnon-phonon scattering. For spatially anisotropic magnetic phases, the thermal conductivity tensor can be highly anisotropic when the magnetic energy scale dominates, since the magnetic degrees of freedom dominate the thermal transport for temperatures well below the magnetic transition temperature. In the opposite limit in which the phonon energy scale dominates, the thermal conductivity will be nearly isotropic, reflecting the isotropic (at low temperatures) phonon dispersion assumed for the honeycomb lattice. We further discuss the extent to which thermal transport properties are influenced by strong spin-orbit induced anisotropic coupling in the local moment regime of insulating magnetic phases. The developed methodology can be applied to any 2D magnon-phonon system, and more importantly to systems where an analytical Bogoliubov transformation cannot be found and magnon bands are not necessarily isotropic.

  3. 3D conductive coupling for efficient generation of prominent Fano resonances in metamaterials

    NASA Astrophysics Data System (ADS)

    Liu, Zhiguang; Liu, Zhe; Li, Jiafang; Li, Wuxia; Li, Junjie; Gu, Changzhi; Li, Zhi-Yuan

    2016-06-01

    We demonstrate a 3D conductive coupling mechanism for the efficient generation of prominent and robust Fano resonances in 3D metamaterials (MMs) formed by integrating vertical U-shape split-ring resonators (SRRs) or vertical rectangular plates along a planar metallic hole array with extraordinary optical transmission (EOT). In such a configuration, intensified vertical E-field is induced along the metallic holes and naturally excites the electric resonances of the vertical structures, which form non-radiative “dark” modes. These 3D conductive “dark” modes strongly interfere with the “bright” resonance mode of the EOT structure, generating significant Fano resonances with both prominent destructive and constructive interferences. The demonstrated 3D conductive coupling mechanism is highly universal in that both 3D MMs with vertical SRRs and vertical plates exhibit the same prominent Fano resonances despite their dramatic structural difference, which is conceptually different from conventional capacitive and inductive coupling mechanisms that degraded drastically upon small structural deviations.

  4. Microfluidic pumping, routing and metering by contactless metal-based electro-osmosis.

    PubMed

    Fu, Xiaotong; Mavrogiannis, Nicholas; Doria, Steven; Gagnon, Zachary

    2015-09-07

    Over the past decade, many microfluidic platforms for fluid processing have been developed in order to perform on-chip fluidic manipulations. Many of these methods, however, require expensive and bulky external supporting equipment, which are not typically applicable for microsystems requiring portability. We have developed a new type of portable contactless metal electro-osmotic micropump capable of on-chip fluid pumping, routing and metering. The pump operates using two pairs of gallium metal electrodes, which are activated using an external voltage source, and separated from a main flow channel by a thin micron-scale PDMS membrane. The thin contactless membrane allows for field penetration and electro-osmotic (EO) flow within the microchannel, but eliminates electrode damage and sample contamination commonly associated with traditional DC electro-osmotic pumps that utilize electrodes in direct contact with the working fluid. The maximum flow rates and pressures generated by the pump using DI water as a working buffer are 10 nL min(-1) and 30 Pa, respectively. With our current design, the maximum operational conductivity where fluid flow is observed is 0.1 mS cm(-1). Due to the small size and simple fabrication procedure, multiple micropump units can be integrated into a single microfluidic device for automated on-chip routing and sample metering applications. We experimentally demonstrated the ability to quantify micropump electro-osmotic flowrate and pressure as a function of applied voltage, and developed a mathematical model capable of predicting the performance of a contactless micropump for a given external load and internal hydrodynamic microchannel resistance. Finally, we showed that by activating specific pumps within a microchannel network, our micropumps are capable of routing microchannel fluid flow and generating plugs of solute.

  5. THE ANALYSIS AND SYNTHESIS OF CONTACTLESS MULTISTROKE CIRCUITS,

    DTIC Science & Technology

    An algebraic method for the solution of problems of contactless switching circuits is given. The same problem was solved (Gr. C. Moisil. Teoria ...it is not physically possible to eliminate this indeterminacy in a given circuit, it is necessary to use suitable transformations to generate a

  6. Analysis of OPACITY and PLAID Protocols for Contactless Smart Cards

    DTIC Science & Technology

    2012-09-01

    and Privacy [16] L. Francis , K. M. Gerhard Hancke and K. Markantonakis, “Practical relay attack on contactless transactions using nfc mobile phones...Allyn and Bacon , 2006. [31] National Insitute of Standards and Technology (NIST), “DRAFT personal identity verification of federal employees and

  7. A CONTACTLESS TRANSMITTER FOR THE M TYPE DATA TRANSMISSION SYSTEM.

    DTIC Science & Technology

    A contactless transmitter employing electromagnetic principles for the M type data transmission system is described. It could be contained in a size 11 standard housing if the six semiconductor main switches are mounted externally. Tests showed that the transmitter will operate satisfactorily at speeds in excess of 3000 rev/min, and that it could form the basis of a brushless dc motor . (Author)

  8. Contactless magnetic manipulation of magnetic particles in a fluid

    NASA Astrophysics Data System (ADS)

    Tokura, S.; Hara, M.; Kawaguchi, N.; Amemiya, N.

    2016-08-01

    The objective of this study was to demonstrate contactless magnetic manipulation of a magnetic particle along a designated orbit among other magnetic particles suspended in a fluid at rest or in motion, and also to understand the behaviors of those surrounding particles during the contactless magnetic manipulation. In addition, the possibility of breaking up chains of clustered magnetic particles under such conditions was also studied. We first describe contactless magnetic manipulation of magnetic particles by feedback control in which the feedback signal was the measured coordinates of the tracked particle. By the feedback control monitoring the location of the tracked particle using a high-speed image analyzer, the reach of the dipole magnetic field created by the magnetized magnetic particles could be kept relatively small. As a result, the tracked magnetic particle could be dragged along the designated orbit by magnetic force. Second, we describe the breaking up of chains of clustered magnetic particles using an alternating magnetic force. The results showed that chain-clustered magnetic particles that had been aggregated under the condition of contactless magnetic manipulation could be broken up reproducibly by an alternating magnetic field. These results constitute useful information for advancements in the handling of magnetic micro- or nanoparticles.

  9. Synergistic plasticity of intrinsic conductance and electrical coupling restores synchrony in an intact motor network

    PubMed Central

    Lane, Brian J; Samarth, Pranit; Ransdell, Joseph L; Nair, Satish S; Schulz, David J

    2016-01-01

    Motor neurons of the crustacean cardiac ganglion generate virtually identical, synchronized output despite the fact that each neuron uses distinct conductance magnitudes. As a result of this variability, manipulations that target ionic conductances have distinct effects on neurons within the same ganglion, disrupting synchronized motor neuron output that is necessary for proper cardiac function. We hypothesized that robustness in network output is accomplished via plasticity that counters such destabilizing influences. By blocking high-threshold K+ conductances in motor neurons within the ongoing cardiac network, we discovered that compensation both resynchronized the network and helped restore excitability. Using model findings to guide experimentation, we determined that compensatory increases of both GA and electrical coupling restored function in the network. This is one of the first direct demonstrations of the physiological regulation of coupling conductance in a compensatory context, and of synergistic plasticity across cell- and network-level mechanisms in the restoration of output. DOI: http://dx.doi.org/10.7554/eLife.16879.001 PMID:27552052

  10. Photocontrol of the functional coupling between photosynthesis and stomatal conductance in the intact leaf

    SciTech Connect

    Zeiger, E.; Field, C.

    1982-08-01

    The photocontrol of the functional coupling between photosynthesis and stomatal conductance in the leaf was investigated in gas exchange experiments using monochromatic light provided by lasers. Net photosynthesis and stomatal conductance were measured in attached leaves of Malva parviflora L. as a function of photon irradiance at 457.9 and 640.0 nanometers. Photosynthetic rates and quantum yields of photosynthesis were higher under red light than under blue, on an absorbed or incident basis. Stomatal conductance was higher under blue than under red light at all intensities. Based on a calculated apparent photon efficiency of conductance, blue and red light had similar effects on conductance at intensities higher than 0.02 millimoles per square meter per second, but blue light was several-fold more efficient at very low photon irradiances. Red light had no effect on conductance at photon irradiances below 0.02 millimoles per square meter per second. These observations support the hypothesis that stomatal conductance is modulated by two photosystems: a blue light-dependent one, driving stomatal opening at low light intensities and a photosynthetically active radiation (PAR)-dependent one operating at higher irradiances. When low intensity blue light was used to illuminate a leaf already irradiated with high intensity, 640 nanometers light, the leaf exhibited substantial increases in stomatal conductance. Net photosynthesis changed only slightly. Additional far-red light increased net photosynthesis without affecting stomatal conductance. These observations indicate that under conditions where the PAR-dependent system is driven by high intensity red light, the blue light-dependent system has an additive effect on stomatal conductance.

  11. Coupled conduction-convection problem for an underground rectangular duct containing three insulated cables

    SciTech Connect

    Liu, Y.; Phan-Thien, N.; Kemp, R.; Luo, X.L.

    1997-03-01

    The coupled heat conduction-convection problem for three insulating cables resting in a rectangular duct filled with air, which is buried underground, is solved by an operator-splitting pseudo-time-stepping finite element method. The method automatically satisfies the continuity of the interfacial temperature and heat flux. The temperature distribution in the metal cores, in the insulating layers, and in the surrounding air and soil, together with the convective flow pattern, are obtained simultaneously. From the profile of the local Nusselt number, which is strongly dependent on the thermal conductivity ratios and weakly dependent on the Rayleigh number, it is concluded that most of the heat transfer takes place via the bottom of the enclosure through a conductive mode.

  12. Gating mechanism of mechanosensitive channel of large conductance: a coupled continuum mechanical-continuum solvation approach.

    PubMed

    Zhu, Liangliang; Wu, Jiazhong; Liu, Ling; Liu, Yilun; Yan, Yuan; Cui, Qiang; Chen, Xi

    2016-12-01

    Gating transition of the mechanosensitive channel of large conductance (MscL) represents a good example of important biological processes that are difficult to describe using atomistic simulations due to the large (submicron) length scale and long (millisecond) time scale. Here we develop a novel computational framework that tightly couples continuum mechanics with continuum solvation models to study the detailed gating behavior of E. coli-MscL. The components of protein molecules are modeled by continuum elements that properly describe their shape, material properties and physicochemical features (e.g., charge distribution). The lipid membrane is modeled as a three-layer material in which the lipid head group and tail regions are treated separately, taking into account the fact that fluidic lipid bilayers do not bear shear stress. Coupling between mechanical and chemical responses of the channel is realized by an iterative integration of continuum mechanics (CM) modeling and continuum solvation (CS) computation. Compared to previous continuum mechanics studies, the present model is capable of capturing the most essential features of the gating process in a much more realistic fashion: due mainly to the apolar solvation contribution, the membrane tension for full opening of MscL is reduced substantially to the experimental measured range. Moreover, the pore size stabilizes constantly during gating because of the intricate interactions of the multiple components of the system, implying the mechanism for sub-conducting states of MscL gating. A significant fraction ([Formula: see text]2/3) of the gating membrane strain is required to reach the first sub-conducting state of our model, which is featured with a relative conductance of 0.115 to the fully opened state. These trends agree well with experimental observations. We anticipate that the coupled CM/CS modeling framework is uniquely suited for the analysis of many biomolecules and their assemblies under external

  13. The effects of fully implicit coupling on heat conduction between a flow field and conduction between a flow field and conduction slab in TRAC-PF1

    SciTech Connect

    Wang, L.C.; Baratta, A.J.; Mahaffy, J.H. )

    1990-01-01

    Numerical techniques used in thermal-hydraulic computer analysis codes must be fast to enable modeling of complex transients and accurate to provide a high degree of fidelity. In an attempt to satisfy these conflicting requirements, the best-estimate code TRAC-PF1 uses a semi-implicit technique to couple heat transfer between a flow field and a conduction slab. To test the accuracy of the current semi-implicit method used in TRAC-PF1, a series of simple tube experiments were modeled with TRAC-PF1 version 3.9B. To overcome identified problems, fully implicit techniques were developed and incorporated into TRAC-PF1. The new methods treat the heat transfer coefficient and wall temperature in the energy source term of both the convection and the conduction equation implicitly. One method uses a linear extrapolation and the other a nonlinear iterative technique. In general, both methods produced higher wall temperature and a lattice quench in better agreement with the experimental data. These methods also eliminated the double-valued results obtained for the other experiments. In general, these techniques have given more accurate results and saved computer time in the film boiling heat transfer regime.

  14. The effect of driven electron-phonon coupling on the electronic conductance of a polar nanowire

    SciTech Connect

    Mardaani, Mohammad Rabani, Hassan; Esmaili, Esmat; Shariati, Ashrafalsadat

    2015-08-07

    A semi-classical model is proposed to explore the effect of electron-phonon coupling on the coherent electronic transport of a polar chain which is confined between two rigid leads in the presence of an external electric field. To this end, we construct the model by means of Green's function technique within the nearest neighbor tight-binding and harmonic approximations. For a time-periodic electric field, the atomic displacements from the equilibrium positions are obtained precisely. The result is then used to compute the electronic transport properties of the chain within the Peierls-type model. The numerical results indicate that the conductance of the system shows interesting behavior in some special frequencies. For each special frequency, there is an electronic quasi-state in which the scattering of electrons by vibrating atoms reaches maximum. The system electronic conductance decreases dramatically at the strong electron-phonon couplings and low electron energies. In the presence of damping forces, the electron-phonon interaction has a less significant effect on the conductance.

  15. Hydraulic conductance and viscous coupling of three-phase layers in angular capillaries

    NASA Astrophysics Data System (ADS)

    Dehghanpour, H.; Aminzadeh, B.; Dicarlo, D. A.

    2011-06-01

    Predicting three-phase relative permeability by network models requires reliable models for hydraulic conductance of films and layers stabilized by capillary forces at the pore level. We solve the creeping flow approximation of the Navier-Stokes equation for stable wetting and intermediate layers in the corner of angular capillaries by using a continuity boundary condition at the layer interface. We find significant coupling between the condensed phases and calculate the generalized mobilities by solving cocurrent and countercurrent flow of wetting and intermediate layers. Finally, we present a simple heuristic model for the generalized mobilities as a function of the geometry and viscosity ratio.

  16. Coupled molecular dynamics-stochastic model for thermal conductivity of ethylene glycol based copper nanofluid.

    PubMed

    Ghosh, M M; Rai, R K

    2014-04-01

    A coupled molecular dynamics (MD)-stochastic simulation based model has been proposed here for the thermal conductivity of ethylene glycol (EG) based copper nanofluid. The model is based on the thermal evolution of the nanoparticles dispersed in the nanofluid which is in contact with a heat source. It is natural that the nanoparticles dispersed in the nanofluid would move randomly by Brownian motion and repeatedly collide with the heat source. During each collision the nanoparticles would extract some heat by conduction mode from the heat source and this heat would be dissipated to the base fluid during Brownian motion by a combination of conduction and microconvection mode. Thus, in addition to normal conductive heat transfer through the base fluid (EG) itself (without nanoparticles) some amount of heat is transferred by the collision of the nanoparticles with the heat source. The extent of this additional heat transfer has been estimated in the present model to estimate the enhancement in thermal conductivity of EG based copper nanofluid, as a function of volume fraction loading of nanoparticles. The prediction of the present model has been compared with the experimental data available in literature, and it has shown a reasonable agreement between the theoretical prediction and the experimental data.

  17. Strongly coupled near-field radiative and conductive heat transfer between planar bodies

    NASA Astrophysics Data System (ADS)

    Messina, Riccardo; Jin, Weiliang; Rodriguez, Alejandro W.

    2016-09-01

    We study the interplay of conductive and radiative heat transfer (RHT) in planar geometries and predict that temperature gradients induced by radiation can play a significant role on the behavior of RHT with respect to gap sizes, depending largely on geometric and material parameters and not so crucially on operating temperatures. Our findings exploit rigorous calculations based on a closed-form expression for the heat flux between two plates separated by vacuum gaps d and subject to arbitrary temperature profiles, along with an approximate but accurate analytical treatment of coupled conduction-radiation in this geometry. We find that these effects can be prominent in typical materials (e.g., silica and sapphire) at separations of tens of nanometers, and can play an even larger role in metal oxides, which exhibit moderate conductivities and enhanced radiative properties. Broadly speaking, these predictions suggest that the impact of RHT on thermal conduction, and vice versa, could manifest itself as a limit on the possible magnitude of RHT at the nanoscale, which asymptotes to a constant (the conductive transfer rate when the gap is closed) instead of diverging at short separations.

  18. Ionic limiting molar conductivity calculation of Li-ion battery electrolyte based on mode coupling theory.

    PubMed

    He, Xiangming; Pu, Weihua; Han, Jingli; Chen, Jian; Lu, Jiufang; Jiang, Changyin; Wan, Chunrong

    2005-12-15

    A method is proposed based on mode coupling theory in which the ion transference number is introduced into the theory. The ionic limiting molar conductivities of LiPF6, LiClO4, LiBF4, LiCF3SO3, Li(CF3SO3)2N, LiC4F9SO3, and LiAsF6 in PC(propylene carbonate), GBL(gamma-butyrolactone), PC(propylene carbonate)/EMC(ethylmethyl carbonate), and PC(propylene carbonate)/DME(dimethoxyethane) are calculated based on this method, which does not involve any adjustable parameter. The results fit well to the literature data which are calculated by an empirically adjusted formula. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes.

  19. Tunnel magnetoresistance and linear conductance of double quantum dots strongly coupled to ferromagnetic leads

    SciTech Connect

    Weymann, Ireneusz

    2015-05-07

    We analyze the spin-dependent linear-response transport properties of double quantum dots strongly coupled to external ferromagnetic leads. By using the numerical renormalization group method, we determine the dependence of the linear conductance and tunnel magnetoresistance on the degree of spin polarization of the leads and the position of the double dot levels. We focus on the transport regime where the system exhibits the SU(4) Kondo effect. It is shown that the presence of ferromagnets generally leads the suppression of the linear conductance due to the presence of an exchange field. Moreover, the exchange field gives rise to a transition from the SU(4) to the orbital SU(2) Kondo effect. We also analyze the dependence of the tunnel magnetoresistance on the double dot levels' positions and show that it exhibits a very nontrivial behavior.

  20. Effects of the Dayside Ionospheric Conductance on Solar Wind-Magnetosphere-Ionosphere Coupling

    NASA Astrophysics Data System (ADS)

    Ohtani, S.; Wing, S.; Merkin, V. G.; Higuchi, T.

    2013-12-01

    In the present study we seek to observationally address the role of ionospheric conductance in the solar wind-magnetosphere coupling in terms of global field-aligned currents (FACs). Solar EUV irradiance changes during a solar cycle, and so does its contribution to the ionospheric conductance. We statistically examine how, for fixed ranges of external driver, the intensities of the R1 and R2 currents and their demarcation latitude depend on solar activity (F10.7). An emphasis is placed on night-side FACs in the dark hemisphere. The result shows that under fixed external conditions, the night-side FACs are more intense for higher solar activity irrespective of their polarities or local time. It is also found that the overall FAC system, therefore the auroral oval, moves equatorward as the solar activity increases. For both current intensity and latitude, the dependence on solar activity is more sensitive for smaller values of F10.7 and it becomes more gradual with increasing F10.7. The intensities of dayside FACs reveal similar F10.7 dependence as expected from the enhancement of the local ionospheric conductance. Interestingly, they also move equatorward with increasing solar activity. We suggest that as the dayside R1 current becomes more intense with increasing solar activity, the magnetosphere shrinks on the day side and expands on the night side. This configurational change of the magnetosphere is considered to affect the energy transport from the solar wind to the magnetosphere, although the details still remain to be understood. We conclude that the ionospheric conductance actively affects the solar wind-magnetosphere-ionosphere coupling.

  1. Effect of incorporation of ethylene glycol into PEDOT:PSS on electron phonon coupling and conductivity

    SciTech Connect

    Lin, Yow-Jon Ni, Wei-Shih; Lee, Jhe-You

    2015-06-07

    The effect of incorporation of ethylene glycol (EG) into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on electron phonon coupling and conductivity is investigated. It is shown that the carrier density (N{sub C}) increases significantly and the carrier mobility (μ) increases slightly at 300 K. The increased intensity of the Raman spectrum between 1400 and 1450 cm{sup −1}, following EG treatment (that is, the quinoid-dominated structures of the PEDOT chain), leads to an increase in the number of polarons (bipolarons), which leads to an increase in N{sub C}. In addition, μ in PEDOT:PSS samples with or without EG addition exhibits a strong temperature dependence, which demonstrates the dominance of tunneling (hopping) at low (high) temperatures. The high conductivity of PEDOT:PSS samples with the addition of EG is attributed to the combined effect of the modification of the electron-phonon coupling and the increase in N{sub C} (μ)

  2. Tunneling conductance through normal metal - superconductor junctions: effects of Rashba spin orbit coupling and magnetic field

    NASA Astrophysics Data System (ADS)

    Kapri, Priyadarshini; Ganguly, Sudin; Basu, Saurabh

    2016-10-01

    In a system consisting of a metal-(s-wave) superconductor junction, we study the conductance characteristics in presence of Rashba spin orbit coupling (RSOC) and an external magnetic field applied along the plane of the sample. With a selective inclusion of the Rashba coupling either in the metallic or in both we note that there is a distinct effect with regard to the magnitude of the Andreev peak that occurs at a biasing voltage lower than the superconducting gap energy. The height of the peak is sensitive to the RSOC (increases with increase in RSOC) for RSOC to be present only in the metallic region, (same is true when RSOC is present throughout the junction), while the peak height is fairly independent when RSOC is solely present in the superconducting region. The in-plane magnetic field has very interesting effects which show up in the form of having a conductance peak at zero bias, thereby making it possible to realize a Majorana bound state.

  3. A coupled theory for chemically active and deformable solids with mass diffusion and heat conduction

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolong; Zhong, Zheng

    2017-10-01

    To analyse the frequently encountered thermo-chemo-mechanical problems in chemically active material applications, we develop a thermodynamically-consistent continuum theory of coupled deformation, mass diffusion, heat conduction and chemical reaction. Basic balance equations of force, mass and energy are presented at first, and then fully coupled constitutive laws interpreting multi-field interactions and evolving equations governing irreversible fluxes are constructed according to the energy dissipation inequality and the chemical kinetics. To consider the essential distinction between mass diffusion and chemical reactions in affecting free energy and dissipations of a highly coupled system, we regard both the concentrations of diffusive species and the extent of reaction as independent state variables. This new formulation then distinguishes between the energy contribution from the diffusive species entering the solid and that from the subsequent chemical reactions occurring among these species and the host solid, which not only interact with stresses or strains in different manners and on different time scales, but also induce different variations of solid microstructures and material properties. Taking advantage of this new description, we further establish a specialized isothermal model to predict precisely the transient chemo-mechanical response of a swelling solid with a proposed volumetric constraint that accounts for material incompressibility. Coupled kinetics is incorporated to capture the volumetric swelling of the solid caused by imbibition of external species and the simultaneous dilation arised from chemical reactions between the diffusing species and the solid. The model is then exemplified with two numerical examples of transient swelling accompanied by chemical reaction. Various ratios of characteristic times of diffusion and chemical reaction are taken into account to shed light on the dependency on kinetic time scales of evolution patterns for

  4. Revised benchmarking of contact-less fingerprint scanners for forensic fingerprint detection: challenges and results for chromatic white light scanners (CWL)

    NASA Astrophysics Data System (ADS)

    Kiltz, Stefan; Leich, Marcus; Dittmann, Jana; Vielhauer, Claus; Ulrich, Michael

    2011-02-01

    Mobile contact-less fingerprint scanners can be very important tools for the forensic investigation of crime scenes. To be admissible in court, data and the collection process must adhere to rules w.r.t. technology and procedures of acquisition, processing and the conclusions drawn from that evidence. Currently, no overall accepted benchmarking methodology is used to support some of the rules regarding the localisation, acquisition and pre-processing using contact-less fingerprint scanners. Benchmarking is seen essential to rate those devices according to their usefulness for investigating crime scenes. Our main contribution is a revised version of our extensible framework for methodological benchmarking of contact-less fingerprint scanners using a collection of extensible categories and items. The suggested main categories describing a contact-less fingerprint scanner are properties of forensic country-specific legal requirements, technical properties, application-related aspects, input sensory technology, pre-processing algorithm, tested object and materials. Using those it is possible to benchmark fingerprint scanners and describe the setup and the resulting data. Additionally, benchmarking profiles for different usage scenarios are defined. First results for all suggested benchmarking properties, which will be presented in detail in the final paper, were gained using an industrial device (FRT MicroProf200) and conducting 18 tests on 10 different materials.

  5. Acoustophoretic contactless transport and handling of matter in air

    PubMed Central

    Foresti, Daniele; Nabavi, Majid; Klingauf, Mirko; Ferrari, Aldo; Poulikakos, Dimos

    2013-01-01

    Levitation and controlled motion of matter in air have a wealth of potential applications ranging from materials processing to biochemistry and pharmaceuticals. We present a unique acoustophoretic concept for the contactless transport and handling of matter in air. Spatiotemporal modulation of the levitation acoustic field allows continuous planar transport and processing of multiple objects, from near-spherical (volume of 0.1–10 μL) to wire-like, without being limited by the acoustic wavelength. The independence of the handling principle from special material properties (magnetic, optical, or electrical) is illustrated with a wide palette of application experiments, such as contactless droplet coalescence and mixing, solid–liquid encapsulation, absorption, dissolution, and DNA transfection. More than a century after the pioneering work of Lord Rayleigh on acoustic radiation pressure, a path-breaking concept is proposed to harvest the significant benefits of acoustic levitation in air. PMID:23858454

  6. Acoustophoretic contactless transport and handling of matter in air.

    PubMed

    Foresti, Daniele; Nabavi, Majid; Klingauf, Mirko; Ferrari, Aldo; Poulikakos, Dimos

    2013-07-30

    Levitation and controlled motion of matter in air have a wealth of potential applications ranging from materials processing to biochemistry and pharmaceuticals. We present a unique acoustophoretic concept for the contactless transport and handling of matter in air. Spatiotemporal modulation of the levitation acoustic field allows continuous planar transport and processing of multiple objects, from near-spherical (volume of 0.1-10 μL) to wire-like, without being limited by the acoustic wavelength. The independence of the handling principle from special material properties (magnetic, optical, or electrical) is illustrated with a wide palette of application experiments, such as contactless droplet coalescence and mixing, solid-liquid encapsulation, absorption, dissolution, and DNA transfection. More than a century after the pioneering work of Lord Rayleigh on acoustic radiation pressure, a path-breaking concept is proposed to harvest the significant benefits of acoustic levitation in air.

  7. The INCAS Project: An Innovative Contact-Less Angular Sensor

    NASA Astrophysics Data System (ADS)

    Ghislanzoni, L.; Di Cintio, A.; Solimando, M.; Parzianello, G.

    2013-09-01

    Angular Positions sensors are widely used in all spacecrafts, including re-entry vehicles and launchers, where mechanisms and pointing-scanning devices are required. The main applications are on mechanisms for TeleMeasure (TM) related to the release and deployment of devices, or on rotary mechanisms such as Solar Array Drive Mechanism (SADM) and Antenna Pointing Mechanism (APM). Longer lifetime (up to 7- 10 years) is becoming a new driver for the coming missions and contact technology sensors often incur in limitations due to the wear of the contacting parts [1].A Self-Compensating Absolute Angular Encoder was developed and tested in the frame of an ESA's ARTES 5.2 project, named INCAS (INnovative Contact-less Angular Sensor). More in particular, the INCAS sensor addresses a market need for contactless angular sensors aimed at replacing the more conventional rotary potentiometers, while featuring the same level of accuracy performances and extending the expected lifetime.

  8. Contactless measurements of charge migration within single molecules

    SciTech Connect

    Nagaya, Kiyonobu; Iwayama, Hiroshi; Sugishima, Akinori; Ohmasa, Yoshinori; Yao, Makoto

    2010-06-07

    Contactless measurements of charge migration were carried out for three pi-conjugated molecules in each of which a bromine atom and an oxygen atom are located on the opposite sides of the aromatic ring. A core hole was generated selectively in the Br atom by x-ray absorption, followed by the Auger cascade, and the subsequent charge migration within the molecule was examined by detecting an O{sup +} ion by means of the coincidence momentum imaging measurements.

  9. Resonance-induced sensitivity enhancement method for conductivity sensors

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Shih, Chi-yuan (Inventor); Li, Wei (Inventor); Zheng, Siyang (Inventor)

    2009-01-01

    Methods and systems for improving the sensitivity of a variety of conductivity sensing devices, in particular capacitively-coupled contactless conductivity detectors. A parallel inductor is added to the conductivity sensor. The sensor with the parallel inductor is operated at a resonant frequency of the equivalent circuit model. At the resonant frequency, parasitic capacitances that are either in series or in parallel with the conductance (and possibly a series resistance) is substantially removed from the equivalent circuit, leaving a purely resistive impedance. An appreciably higher sensor sensitivity results. Experimental verification shows that sensitivity improvements of the order of 10,000-fold are possible. Examples of detecting particulates with high precision by application of the apparatus and methods of operation are described.

  10. Coupled Ablation, Heat Conduction, Pyrolysis, Shape Change and Spallation of the Galileo Probe

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Y.-K.; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    The Galileo probe enters the atmosphere of Jupiter in December 1995. This paper presents numerical methodology and detailed results of our final pre-impact calculations for the heat shield response. The calculations are performed using a highly modified version of a viscous shock layer code with massive radiation coupled with a surface thermochemical ablation and spallation model and with the transient in-depth thermal response of the charring and ablating heat shield. The flowfield is quasi-steady along the trajectory, but the heat shield thermal response is dynamic. Each surface node of the VSL grid is coupled with a one-dimensional thermal response calculation. The thermal solver includes heat conduction, pyrolysis, and grid movement owing to surface recession. Initial conditions for the heat shield temperature and density were obtained from the high altitude rarefied-flow calculations of Haas and Milos. Galileo probe surface temperature, shape, mass flux, and element flux are all determined as functions of time along the trajectory with spallation varied parametrically. The calculations also estimate the in-depth density and temperature profiles for the heat shield. All this information is required to determine the time-dependent vehicle mass and drag coefficient which are necessary inputs for the atmospheric reconstruction experiment on board the probe.

  11. Electromagnetic penetration through narrow slots in conducting surfaces and coupling to structures on the shadow side

    SciTech Connect

    Reed, E.K.; Butler, C.M. . Dept. of Electrical and Computer Engineering)

    1990-07-01

    Electromagnetic field penetration through a curved narrow slot in a planar conducting surface and coupling to a curved, loaded thin wire on the shadow side are determined in the time domain (TD) and the frequency domain (FD) by integral equation methods. Coupled integral equations are derived and solved numerically for the equivalent magnetic current in the slot and the electric current on the wire, from which the field that penetrates the slotted surface is determined. One employs a piecewise linear approximation of the unknown currents and performs equation enforcement by pulse testing. The resulting TD equations are solved by a scheme incorporating a finite-difference approximation for a second partial time derivative which allows one to solve for the unknown currents at a discrete time instant t + 1 in terms of the known excitation and currents calculated at a discrete time instant t and earlier. The FD equations are solved by the method of moments. A hybrid time-domain integral equation -- finite-difference time-domain solution technique is described whereby one solves for the field which penetrates a slotted cavity-backed surface. One models the fields in the exterior region and in the slot with integral operators and models the fields inside the cavity with a discretized form of Maxwell's equations. Narrow slots following various contours were chemically etched in thin bass sheets and an apparatus was fabricated to measure shadow-side fields, electric current on a thin wire on the shadow side, and, separately, fields inside a rectangular cavity which backed the slotted brass sheet. The experimentation was conducted at the Lawrence Livermore National Laboratory on a frequency-domain test range employing a monocone source over a large ground plane. One observes very good agreement among the experimental and theoretical results.

  12. Conductance through a potential barrier embedded in a Luttinger liquid: Nonuniversal scaling at strong coupling

    NASA Astrophysics Data System (ADS)

    Aristov, D. N.; Wölfle, P.

    2009-07-01

    We calculate the linear response conductance of electrons in a Luttinger liquid with arbitrary interaction g2 , and subject to a potential barrier of arbitrary strength, as a function of temperature. We map the Hamiltonian in the basis of scattering states into an effective low energy Hamiltonian in current algebra form. First the renormalization group (RG) equation for weak interaction is derived in the current operator language both using the operator product expansion and the equation of motion method. To access the strong coupling regime, two methods of deducing the RG equation from perturbation theory, based on the scaling hypothesis and on the Callan-Symanzik formulation, are discussed. The important role of scale-independent terms is emphasized. The latter depend on the regularization scheme used (length versus temperature cutoff). Analyzing the perturbation theory in the fermionic representation, the diagrams contributing to the renormalization group β -function are identified. A universal part of the β -function is given by a ladder series and summed to all orders in g2 . First nonuniversal corrections beyond the ladder series are discussed and are shown to differ from the exact solutions obtained within conformal field theory which use a different regularization scheme. The RG equation for the temperature-dependent conductance is solved analytically. Our result agrees with known limiting cases.

  13. Magneto-optical conductivity in graphene including electron-phonon coupling

    NASA Astrophysics Data System (ADS)

    Pound, Adam; Carbotte, J. P.; Nicol, E. J.

    2012-03-01

    We show how coupling to an Einstein phonon ωE affects the absorption peaks seen in the optical conductivity of graphene under a magnetic field B. The energies and widths of the various lines are shifted, and additional peaks arise in the spectrum. Some of these peaks are Holstein sidebands, resulting from the transfer of spectral weight in each Landau level (LL) into phonon-assisted peaks in the spectral function. Other additional absorption peaks result from transitions involving split LLs, which occur when a LL falls sufficiently close to a peak in the self-energy. We establish the selection rules for the additional transitions and characterize the additional absorption peaks. For finite chemical potential, spectral weight is asymmetrically distributed about the Dirac point; we discuss how this causes an asymmetry in the transitions due to left- and right-handed circularly polarized light and therefore oscillatory behavior in the imaginary part of the off-diagonal Hall conductivity. We also find that the semiclassical cyclotron resonance region is renormalized by an effective-mass factor but is not directly affected by the additional transitions. Last, we discuss how the additional transitions can manifest in broadened, rather than split, absorption peaks due to large scattering rates seen in experiment.

  14. Two-dimensional electron gas in the regime of strong light-matter coupling: Dynamical conductivity and all-optical measurements of Rashba and Dresselhaus coupling

    NASA Astrophysics Data System (ADS)

    Yudin, Dmitry; Shelykh, Ivan A.

    2016-10-01

    A nonperturbative interaction of an electronic system with a laser field can substantially modify its physical properties. In particular, in two-dimensional (2D) materials with a lack of inversion symmetry, the achievement of a regime of strong light-matter coupling allows direct optical tuning of the strength of the Rashba spin-orbit interaction (SOI). Capitalizing on these results, we build a theory of the dynamical conductivity of a 2D electron gas with both Rashba and Dresselhaus SOIs coupled to an off-resonant high-frequency electromagnetic wave. We argue that strong light-matter coupling modifies qualitatively the dispersion of the electrons and can be used as a powerful tool to probe and manipulate the coupling strengths and adjust the frequency range where optical conductivity is essentially nonzero.

  15. Surface potential barrier in m-plane GaN studied by contactless electroreflectance

    NASA Astrophysics Data System (ADS)

    Janicki, Lukasz; Misiewicz, Jan; Cywiński, Grzegorz; Sawicka, Marta; Skierbiszewski, Czeslaw; Kudrawiec, Robert

    2016-02-01

    Contactless electroreflectance (CER) is used to study the surface potential barrier in m-plane GaN UN+ [GaN (d = 20,30,50,70 nm)/GaN:Si] structures grown by using molecular beam epitaxy. Clear bandgap-related transitions followed by Franz-Keldysh oscillations (FKO) have been observed in the CER spectra of all samples at room temperature. The built-in electric fields in the undoped cap layers have been determined from the FKO period. From the built-in electric field and the undoped GaN layer thickness, the Fermi level location at the air-exposed m-plane GaN surface has been estimated as 0.42 ± 0.05 eV below the conduction band.

  16. Effect of taurine depletion on excitation-contraction coupling and Cl- conductance of rat skeletal muscle.

    PubMed

    De Luca, A; Pierno, S; Camerino, D C

    1996-01-25

    The pharmacological action of taurine on skeletal muscle is to stabilize sarcolemma by increasing macroscopic conductance to Cl- (GCl), whereas a proposed physiological role for the amino acid is to modulate excitation-contraction coupling mechanism via Ca2+ availability. To get insight in the physiological role of taurine in skeletal muscle, the effects of its depletion were evaluated on voltage threshold for mechanical activation and GCl with the two intracellular microelectrode method in 'point' voltage clamp mode and current clamp mode, respectively. The experiments were performed on extensor digitorum longus muscle fibers from rats depleted of taurine by a chronic 4 week treatment with guanidinoethane sulfonate, a known inhibitor of taurine transporter. The treatment significantly modified the mechanical threshold of striated fibers; i.e. at each pulse duration they needed significantly less depolarization to contract and the fitted rheobase voltage was more negative by 10 mV with respect to untreated muscle fibers. In parallel, the treatment with guanidinoethane sulfonate produced a significant 40% lowering of GCl. In vitro application of 60 mM of taurine to such depleted muscles almost completely restored the mechanical threshold and increased GCl even above the value of untreated control. However, in vitro application of 60 mM of either taurine or guanidinoethane sulfonate to untreated control muscles did not cause any change of the mechanical threshold but increased GCl by 40% and 21%, respectively. Furthermore, 100 microM of the S-(-) enantiomer of 2-(p-chlorophenoxy)propionic acid almost fully blocked GCl but did not produce any change in the mechanical threshold of normal muscle fibers. The present results show that the large amount of intracellular taurine plays a role in the excitation-contraction coupling mechanism of striated muscle fibers. This action is independent from any effect involving muscle Cl- channels, but it is likely mediated by the

  17. Some Aspects of PVT Low Supersaturation Nucleation and Contactless Crystal Growth

    NASA Technical Reports Server (NTRS)

    Grasza, K.; Palosz, W.

    1996-01-01

    The basic principles of the contactless growth of crystals from the vapor in combination with the process of low-supersaturation nucleation are discussed. The mathematical formulation of the morphological stability criterion in vapor growth systems is given and its implications for contactless growth technique are analyzed. A diagram for selection of proper temperature conditions for growth of CdTe crystals is presented.

  18. Determination of anions using monolithic capillary column ion chromatography with end-to-end differential contactless conductometric detectors under resonance approach.

    PubMed

    Zhang, Zhenli; Li, Dongdong; Liu, Xueyong; Subhani, Qamar; Zhu, Yan; Kang, Qi; Shen, Dazhong

    2012-06-21

    An end-to-end differential measurement approach with capacitively coupled contactless conductivity detection (C(4)D) was applied to anion-exchange monolithic capillary column ion chromatography. The column was prepared by thermally initiated radical polymerization of poly(glycidyl methacrylate) in a fused-silica capillary of 320 μm i.d. and modified by quaternary ammonium latex surface coating. Two C(4)Ds were placed near both ends of the capillary column and the output difference between them was measured. With 15 mM potassium hydrogen phthalate used as the eluent, good separation of a mixture of inorganic anions (F(-), Cl(-), NO(2)(-), NO(3)(-)) was achieved. The detection limits of conventional C(4)D are 1.6, 0.28, 0.53, and 0.47 mg L(-1) for F(-), Cl(-), NO(2)(-), and NO(3)(-), respectively. To further enhance the sensitivity, the capacitive impedance from C(4)D was neutralized by an inductive impedance from a piezoelectric resonator. An increase in sensitivity by a factor of 7-8 was achieved in the resonating C(4)D in comparison with the conventional C(4)D. The detection limits of the resonating C(4)D are 0.23, 0.041, 0.065, and 0.059 mg L(-1) for F(-), Cl(-), NO(2)(-), and NO(3)(-), respectively. The response of the resonating C(4)D was analyzed based on an equivalent circuit model.

  19. Determinants affecting consumer adoption of contactless credit card: an empirical study.

    PubMed

    Wang, Yu-Min

    2008-12-01

    The contactless credit card is one of the most promising technological innovations in the field of electronic payments. It provides consumers with greater control of payments, convenience, and transaction speed. However, contactless credit cards have yet to gain significant rates of adoption in the marketplace. Thus, effort must be made to identify factors affecting consumer adoption of contactless credit cards. Based on the technology acceptance model, innovation diffusion theory, and the relevant literature, seven variables (perceived usefulness, perceived ease of use, compatibility, perceived risk, trust, consumer involvement, availability of infrastructure) are proposed to help predict consumer adoption of contactless credit cards. Data collected from 312 respondents in Taiwan is tested against the proposed prediction model using the logistic regression approach. The results and implications of our study contribute to an expanded understanding of the factors that affect consumer adoption of contactless credit cards.

  20. Mechanical coupling of the multiple structural elements of the large-conductance mechanosensitive channel during expansion

    PubMed Central

    Li, Jie; Guo, Jianli; Ou, Xiaomin; Zhang, Mingfeng; Li, Yuezhou; Liu, Zhenfeng

    2015-01-01

    The prokaryotic mechanosensitive channel of large conductance (MscL) is a pressure-relief valve protecting the cell from lysing during acute osmotic downshock. When the membrane is stretched, MscL responds to the increase of membrane tension and opens a nonselective pore to about 30 Å wide, exhibiting a large unitary conductance of ∼3 nS. A fundamental step toward understanding the gating mechanism of MscL is to decipher the molecular details of the conformational changes accompanying channel opening. By applying fusion-protein strategy and controlling detergent composition, we have solved the structures of an archaeal MscL homolog from Methanosarcina acetivorans trapped in the closed and expanded intermediate states. The comparative analysis of these two new structures reveals significant conformational rearrangements in the different domains of MscL. The large changes observed in the tilt angles of the two transmembrane helices (TM1 and TM2) fit well with the helix-pivoting model derived from the earlier geometric analyses based on the previous structures. Meanwhile, the periplasmic loop region transforms from a folded structure, containing an ω-shaped loop and a short β-hairpin, to an extended and partly disordered conformation during channel expansion. Moreover, a significant rotating and sliding of the N-terminal helix (N-helix) is coupled to the tilting movements of TM1 and TM2. The dynamic relationships between the N-helix and TM1/TM2 suggest that the N-helix serves as a membrane-anchored stopper that limits the tilts of TM1 and TM2 in the gating process. These results provide direct mechanistic insights into the highly coordinated movement of the different domains of the MscL channel when it expands. PMID:26261325

  1. Shot noise and linear conductance in a transport through quantum dot coupled to polarized leads

    NASA Astrophysics Data System (ADS)

    Golub, A.

    2009-04-01

    We study the influence of polarized leads and of magnetic field on the noise power and on transport through a link which may be a quantum dot or a point junction. We suggest that such link is tuned to the local spin regime and reveals Kondo type behavior. The implication of superconductivity is also analyzed in the case when one of the leads is a superconductor. Specifically, we calculate the noise power to the third order in the Kondo coupling. With the help of fluctuation-dissipation theorem we can further define the linear conductance as a function of the polarization and magnetic field. For dot spin operators we used their representation in terms of mixed Dirac and Majorana fermions. The important output of the derivation with both, spin polarization and magnetic field included, is the potential scattering contribution which acquires logarithmic dependence on the band width. Motivated by experiment [1] we analyze a set configuration when only one lead is polarized. The Kondo temperature is defined with the help of renormalization group equations. In particular, some of these equations follow from the invariance of the shot noise under scale transformation.

  2. Steady-State and Transient Boundary Element Methods for Coupled Heat Conduction

    NASA Technical Reports Server (NTRS)

    Kontinos, Dean A.

    1997-01-01

    Boundary element algorithms for the solution of steady-state and transient heat conduction are presented. The algorithms are designed for efficient coupling with computational fluid dynamic discretizations and feature piecewise linear elements with offset nodal points. The steady-state algorithm employs the fundamental solution approach; the integration kernels are computed analytically based on linear shape functions, linear elements, and variably offset nodal points. The analytic expressions for both singular and nonsingular integrands are presented. The transient algorithm employs the transient fundamental solution; the temporal integration is performed analytically and the nonsingular spatial integration is performed numerically using Gaussian quadrature. A series solution to the integration is derived for the instance of a singular integrand. The boundary-only character of the algorithm is maintained by integrating the influence coefficients from initial time. Numerical results are compared to analytical solutions to verify the current boundary element algorithms. The steady-state and transient algorithms are numerically shown to be second-order accurate in space and time, respectively.

  3. Contactless mapping of rhythmical phenomena in tissue perfusion using PPGI

    NASA Astrophysics Data System (ADS)

    Huelsbusch, Markus; Blazek, Vladimir

    2002-04-01

    This paper presents the experimental setup and preliminary results of a near infrared CCD camera based Photoplethysmography Imaging (PPGI) system, which has been shown to be suitable for contactless and spatially resolved assessment of rhythmical blood volume changes in the skin. To visualize the complex rhythmical patterns in the dermal perfusion the Wavelet Transform is utilized. It is able to jointly assess time and frequency behavior of signals and thus allows to analyze instationary oscillations and variabilities in the different human rhythmics. The presented system is expected to provide new insights into the functional sequences of physiological tissue perfusion as well as of the perfusion status in ulcer formation and wound healing.

  4. Zero-conductance resonances and spin polarizations in three-terminal rings in the presence of spin-orbit coupling

    SciTech Connect

    Zhai, Li-Xue; Wang, Yan; Liu, Jian-Jun

    2014-11-28

    Spin dependent transport in one-dimensional (1D) three-terminal rings is investigated in the presence of the Rashba spin-orbit coupling (RSOC). We focus on zero-conductance resonances and spin polarizations. For these purposes, the transmission functions are derived analytically. The total conductances are analyzed in the complex energy plane with a focus on the zero-pole structure characteristic of transmission (anti)resonances. The spin polarizations in symmetrically and asymmetrically coupled three-terminal rings are studied as a function of the incident electron energy. It is found that in the absence of the RSOC there are three kinds of conductance zeros. In the presence of the RSOC, the zeros of the first and the third kinds are lifted, while some of the second kind persist. The lifting of the conductance zeros is related to the breaking of the spin-reversal symmetry, and the lifted conductance zeros evolve into spin polarization zeros.

  5. Contactless, photoinitiated snap-through in azobenzene-functionalized polymers

    PubMed Central

    Shankar, M. Ravi; Smith, Matthew L.; Tondiglia, Vincent P.; Lee, Kyung Min; McConney, Michael E.; Wang, David H.; Tan, Loon-Seng; White, Timothy J.

    2013-01-01

    Photomechanical effects in polymeric materials and composites transduce light into mechanical work. The ability to control the intensity, polarization, placement, and duration of light irradiation is a distinctive and potentially useful tool to tailor the location, magnitude, and directionality of photogenerated mechanical work. Unfortunately, the work generated from photoresponsive materials is often slow and yields very small power densities, which diminish their potential use in applications. Here, we investigate photoinitiated snap-through in bistable arches formed from samples composed of azobenzene-functionalized polymers (both amorphous polyimides and liquid crystal polymer networks) and report orders-of-magnitude enhancement in actuation rates (approaching 102 mm/s) and powers (as much as 1 kW/m3). The contactless, ultra-fast actuation is observed at irradiation intensities <<100 mW/cm2. Due to the bistability and symmetry of the snap-through, reversible and bidirectional actuation is demonstrated. A model is developed to elucidate the underlying mechanics of the snap-through, specifically focusing on isolating the role of sample geometry, mechanical properties of the materials, and photomechanical strain. Using light to trigger contactless, ultrafast actuation in an otherwise passive structure is a potentially versatile tool to use in mechanical design at the micro-, meso-, and millimeter scales as actuators, as well as switches that can be triggered from large standoff distances, impulse generators for microvehicles, microfluidic valves and mixers in laboratory-on-chip devices, and adaptive optical elements. PMID:24190994

  6. The biometric recognition on contactless multi-spectrum finger images

    NASA Astrophysics Data System (ADS)

    Kang, Wenxiong; Chen, Xiaopeng; Wu, Qiuxia

    2015-01-01

    This paper presents a novel multimodal biometric system based on contactless multi-spectrum finger images, which aims to deal with the limitations of unimodal biometrics. The chief merits of the system are the richness of the permissible texture and the ease of data access. We constructed a multi-spectrum instrument to simultaneously acquire three different types of biometrics from a finger: contactless fingerprint, finger vein, and knuckleprint. On the basis of the samples with these characteristics, a moderate database was built for the evaluation of our system. Considering the real-time requirements and the respective characteristics of the three biometrics, the block local binary patterns algorithm was used to extract features and match for the fingerprints and finger veins, while the Oriented FAST and Rotated BRIEF algorithm was applied for knuckleprints. Finally, score-level fusion was performed on the matching results from the aforementioned three types of biometrics. The experiments showed that our proposed multimodal biometric recognition system achieves an equal error rate of 0.109%, which is 88.9%, 94.6%, and 89.7% lower than the individual fingerprint, knuckleprint, and finger vein recognitions, respectively. Nevertheless, our proposed system also satisfies the real-time requirements of the applications.

  7. Electron-phonon coupling and thermal conductance at a metal-semiconductor interface: First-principles analysis

    SciTech Connect

    Sadasivam, Sridhar; Fisher, Timothy S.; Waghmare, Umesh V.

    2015-04-07

    The mechanism of heat transfer and the contribution of electron-phonon coupling to thermal conductance of a metal-semiconductor interface remains unclear in the present literature. We report ab initio simulations of a technologically important titanium silicide (metal)–silicon (semiconductor) interface to estimate the Schottky barrier height, and the strength of electron-phonon and phonon-phonon heat transfer across the interface. The electron and phonon dispersion relations of TiSi{sub 2} with C49 structure and the TiSi{sub 2}-Si interface are obtained using first-principles calculations within the density functional theory framework. These are used to estimate electron-phonon linewidths and the associated Eliashberg function that quantifies coupling. We show that the coupling strength of electrons with interfacial phonon modes is of the same order of magnitude as coupling of electrons to phonon modes in the bulk metal, and its contribution to electron-phonon interfacial conductance is comparable to the harmonic phonon-phonon conductance across the interface.

  8. Contactless Electroluminescence Imaging for Cell and Module Characterization

    SciTech Connect

    Johnston, Steve

    2015-06-14

    Module performance can be characterized by imaging using baseline and periodic images to track defects and degradation. Both thermal images, which can be acquired during sunny operating conditions, and photoluminescence images, which could be acquired at night, can be collected without electrical connection. Electroluminescence (EL) images, which are useful to detect many types of defects such as cracks, interconnect and solder faults, and resistances, have typically required electrical connection to drive current in the cells and modules. Here, a contactless EL imaging technique is proposed, which provides an EL image without the need for electrical connection to drive current through the module. Such EL imaging has the capability to be collected at night without disruption to daytime power generation.

  9. Theoretical and numerical approaches to the forward problem and sensitivity calculation of a novel contactless inductive flow tomography (CIFT)

    NASA Astrophysics Data System (ADS)

    Yin, W.; Peyton, A. J.; Stefani, F.; Gerbeth, G.

    2009-10-01

    A completely contactless flow measurement technique based on the principle of EM induction measurements—contactless inductive flow tomography (CIFT)—has been previously reported by a team based at Forschungszentrum Dresden-Rossendorf (FZD). This technique is suited to the measurement of velocity fields in high conductivity liquids, and the possible applications range from monitoring metal casting and silicon crystal growth in industry to gaining insights into the working of the geodynamo. The forward problem, i.e. calculating the induced magnetic field from a known velocity profile, can be described as a linear relationship when the magnetic Reynolds number is small. Previously, an integral equation method was used to formulate the forward problem; however, although the sensitivity matrices were calculated, they were not explicitly expressed and computation involved the solution of an ill-conditioned system of equations using a so-called deflation method. In this paper, we present the derivation of the sensitivity matrix directly from electromagnetic field theory and the results are expressed very concisely as the cross product of two field vectors. A numerical method based on a finite difference method has also been developed to verify the formulation. It is believed that this approach provides a simple yet fast route to the forward solution of CIFT. Furthermore, a method for sensor design selection based on eigenvalue analysis is presented.

  10. Benchmarking contactless acquisition sensor reproducibility for latent fingerprint trace evidence

    NASA Astrophysics Data System (ADS)

    Hildebrandt, Mario; Dittmann, Jana

    2015-03-01

    Optical, nano-meter range, contactless, non-destructive sensor devices are promising acquisition techniques in crime scene trace forensics, e.g. for digitizing latent fingerprint traces. Before new approaches are introduced in crime investigations, innovations need to be positively tested and quality ensured. In this paper we investigate sensor reproducibility by studying different scans from four sensors: two chromatic white light sensors (CWL600/CWL1mm), one confocal laser scanning microscope, and one NIR/VIS/UV reflection spectrometer. Firstly, we perform an intra-sensor reproducibility testing for CWL600 with a privacy conform test set of artificial-sweat printed, computer generated fingerprints. We use 24 different fingerprint patterns as original samples (printing samples/templates) for printing with artificial sweat (physical trace samples) and their acquisition with contactless sensory resulting in 96 sensor images, called scan or acquired samples. The second test set for inter-sensor reproducibility assessment consists of the first three patterns from the first test set, acquired in two consecutive scans using each device. We suggest using a simple feature space set in spatial and frequency domain known from signal processing and test its suitability for six different classifiers classifying scan data into small differences (reproducible) and large differences (non-reproducible). Furthermore, we suggest comparing the classification results with biometric verification scores (calculated with NBIS, with threshold of 40) as biometric reproducibility score. The Bagging classifier is nearly for all cases the most reliable classifier in our experiments and the results are also confirmed with the biometric matching rates.

  11. Experimental Study of the Low Supersaturation Nucleation in Crystal Growth by Contactless Physical Vapor Transport

    NASA Technical Reports Server (NTRS)

    Grasza, K.; Palosz, W.; Trivedi, S. B.

    1998-01-01

    The process of the development of the nuclei and of subsequent seeding in 'contactless' physical vapor transport is investigated experimentally. Consecutive stages of the Low Supersaturation Nucleation in 'contactless' geometry for growth of CdTe crystals from the vapor are shown. The effects of the temperature field, geometry of the system, and experimental procedures on the process are presented and discussed. The experimental results are found to be consistent with our earlier numerical modeling results.

  12. Rational Coupled Dynamics Network Manipulation Rescues Disease-Relevant Mutant Cystic Fibrosis Transmembrane Conductance Regulator

    PubMed Central

    Proctor, Elizabeth A.; Kota, Pradeep; Aleksandrov, Andrei A.; He, Lihua; Riordan, John R.; Dokholyan, Nikolay V.

    2014-01-01

    Many cellular functions necessary for life are tightly regulated by protein allosteric conformational change, and correlated dynamics between protein regions has been found to contribute to the function of proteins not previously considered allosteric. The ability to map and control such dynamic coupling would thus create opportunities for the extension of current therapeutic design strategy. Here, we present an approach to determine the networks of residues involved in the transfer of correlated motion across a protein, and apply our approach to rescue disease-causative mutant cystic fibrosis transmembrane regulator (CFTR) ion channels, ΔF508 and ΔI507, which together constitute over 90% of cystic fibrosis cases. We show that these mutations perturb dynamic coupling within the first nucleotide-binding domain (NBD1), and uncover a critical residue that mediates trans-domain coupled dynamics. By rationally designing a mutation to this residue, we improve aberrant dynamics of mutant CFTR as well as enhance surface expression and function of both mutants, demonstrating the rescue of a disease mutation by rational correction of aberrant protein dynamics. PMID:25685315

  13. [Study on Chaotic Detection Method of Pacemaker Contact-Less Power Supply].

    PubMed

    Zhou, Chenghu; Huang, Mingming; Li, Songtao

    2015-12-01

    In order to improve the reliability of cardiac pacemaker contact-less power supply technology, this paper proposes a novel application of wireless feedback voltage stabilizing technology to adjust heart disease patients with inner power supply filter circuit output voltage and current control method, to keep the output voltage stability, and to ensure that the super capacitor and cardiac pacemaker to get a stable power supply. To implement the real-time accurate voltage control with considering the primary and secondary side inductance coupling coefficient changes, the change of the external power supply voltage and load, it is necessary to test thee real-time and accurate output voltage and current value after rectifying filtering. Therefore, based on the chaotic control theory, we adopted method of phase diagram on the basis of the quick observation after rectifying filtering, so that the method of voltage and current could improve the detection time of the circuit. The phase diagram of proposed control method can be divided into 8 segments, and we got 7 zero-extreme points. When these zero-extreme points are detected, according to extreme points of the zero instantaneous values, the corresponding average values of voltage and current were obtained. Simulation and experimental results showed that using the above method can shorten the response time to less than switch devices 1/2 switching cycles, thus validating the effectiveness and feasibility of the proposed detection algorithm.

  14. Contactless electroreflectance spectroscopy of optical transitions in low dimensional semiconductor structures

    NASA Astrophysics Data System (ADS)

    Misiewicz, J.; Kudrawiec, R.

    2012-06-01

    The authors present the application of contactless electroreflectance (CER) spectroscopy to study optical transitions in low dimensional semiconductor structures including quantum wells (QWs), step-like QWs, quantum dots (QDs), quantum dashes (QDashes), QDs and QDashes embedded in a QW, and QDashes coupled with a QW. For QWs optical transitions between the ground and excited states as well as optical transitions in QW barriers and step-like barriers have been clearly observed in CER spectra. Energies of these transitions have been compared with theoretical calculations and in this way the band structure has been determined for the investigated QWs. For QD and QDash structures optical transitions in QDs and QDashes as well as optical transitions in the wetting layer have been identified. For QDs and QDashes surrounded by a QW, in addition to energies of QD and QDash transitions, energies of optical transitions in the surrounded QW have been measured and the band structure has been determined for the surrounded QW. Finally some differences, which can be observed in CER and photo-reflectance spectra, have been presented and discussed for selected QW and QD structures.

  15. Numerical Modeling of Physical Vapor Transport in Contactless Crystal Growth Geometry

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Lowry, S.; Krishnam, A.; Przekwas, A.; Grasza, K.

    1998-01-01

    Growth from the vapor under conditions of limited contact with the walls of the growth ampoule is beneficial for the quality of the growing crystal due to reduced stress and contamination which may be caused by interactions with the growth container. The technique may be of a particular interest for studies on crystal growth under microgravity conditions: elimination of some factors affecting the crystal quality may make interpretation of space-conducted processes more conclusive and meaningful. For that reason, and as a part of our continuing studies on 'contactless' growth technique, we have developed a computational model of crystal growth process in such system. The theoretical model was built, and simulations were performed using the commercial computational fluid dynamics code, (CFD) ACE. The code uses an implicit finite volume formulation with a gray discrete ordinate method radiation model which accounts for the diffuse absorption and reflection of radiation throughout the furnace. The three-dimensional model computes the heat transfer through the crystal, quartz, and gas both inside and outside the ampoule, and mass transport from the source to the crystal and the sink. The heat transport mechanisms by conduction, natural convection, and radiation, and mass transport by diffusion and convection are modeled simultaneously and include the heat of the phase transition at the solid-vapor interfaces. As the thermal boundary condition, temperature profile along the walls of the furnace is used. For different thermal profiles and furnace and ampoule dimensions, the crystal growth rate and development of the crystal-vapor and source-vapor interfaces (change of the interface shape and location with time) are obtained. Super/under-saturation in the ampoule is determined and critical factors determining the 'contactless' growth conditions are identified and discussed. The relative importance of the ampoule dimensions and geometry, the furnace dimensions and its

  16. Using Coupled Mesoscale Experiments and Simulations to Investigate High Burn-Up Oxide Fuel Thermal Conductivity

    NASA Astrophysics Data System (ADS)

    Teague, Melissa C.; Fromm, Bradley S.; Tonks, Michael R.; Field, David P.

    2014-12-01

    Nuclear energy is a mature technology with a small carbon footprint. However, work is needed to make current reactor technology more accident tolerant and to allow reactor fuel to be burned in a reactor for longer periods of time. Optimizing the reactor fuel performance is essentially a materials science problem. The current understanding of fuel microstructure have been limited by the difficulty in studying the structure and chemistry of irradiated fuel samples at the mesoscale. Here, we take advantage of recent advances in experimental capabilities to characterize the microstructure in 3D of irradiated mixed oxide (MOX) fuel taken from two radial positions in the fuel pellet. We also reconstruct these microstructures using Idaho National Laboratory's MARMOT code and calculate the impact of microstructure heterogeneities on the effective thermal conductivity using mesoscale heat conduction simulations. The thermal conductivities of both samples are higher than the bulk MOX thermal conductivity because of the formation of metallic precipitates and because we do not currently consider phonon scattering due to defects smaller than the experimental resolution. We also used the results to investigate the accuracy of simple thermal conductivity approximations and equations to convert 2D thermal conductivities to 3D. It was found that these approximations struggle to predict the complex thermal transport interactions between metal precipitates and voids.

  17. Interplay of Rashba spin orbit coupling and disorder in the conductance properties of a four terminal junction device

    NASA Astrophysics Data System (ADS)

    Ganguly, Sudin; Basu, Saurabh

    2016-04-01

    We report a thorough theoretical investigation on the quantum transport of a disordered four terminal device in the presence of Rashba spin orbit coupling (RSOC) in two dimensions. Specifically we compute the behaviour of the longitudinal (charge) conductance, spin Hall conductance and spin Hall conductance fluctuation as a function of the strength of disorder and Rashba spin orbit interaction using the Landauer Büttiker formalism via Green's function technique. Our numerical calculations reveal that both the conductances diminish with disorder. At smaller values of the RSOC parameter, the longitudinal and spin Hall conductances increase, while both vanish in the strong RSOC limit. The spin current is more drastically affected by both disorder and RSOC than its charge counterpart. The spin Hall conductance fluctuation does not show any universality in terms of its value and it depends on both disorder as well as on the RSOC strength. Thus the spin Hall conductance fluctuation has a distinct character compared to the fluctuation in the longitudinal conductance. Further one parameter scaling theory is studied to assess the transition to a metallic regime as claimed in literature and we find no confirmation about the emergence of a metallic state induced by RSOC.

  18. Capacitively coupled pickup in MCP-based photodetectors using a conductive metallic anode

    NASA Astrophysics Data System (ADS)

    Angelico, E.; Seiss, T.; Adams, B.; Elagin, A.; Frisch, H.; Spieglan, E.

    2017-02-01

    We have designed and tested a robust 20×20 cm2 thin metal film internal anode capacitively coupled to an external array of signal pads or micro-strips for use in fast microchannel plate photodetectors. The internal anode, in this case a 10 nm-thick NiCr film deposited on a 96% pure Al2O3 3 mm-thick ceramic plate and connected to HV ground, provides the return path for the electron cascade charge. The multi-channel pickup array consists of a printed-circuit card or glass plate with metal signal pickups on one side and the signal ground plane on the other. The pickup can be put in close proximity to the bottom outer surface of the sealed photodetector, with no electrical connections through the photodetector hermetic vacuum package other than a single ground connection to the internal anode. Two pickup patterns were tested using a small commercial MCP-PMT as the signal source: 1) parallel 50 Ω 25-cm-long micro-strips with an analog bandwidth of 1.5 GHz, and 2) a 20×20 cm2 array of 2-dimensional square 'pads' with sides of 1.27 cm or 2.54 cm. The rise-time of the fast input pulse is maintained for both pickup patterns. For the pad pattern, we observe 80% of the directly coupled amplitude. For the strip pattern we measure 34% of the directly coupled amplitude on the central strip of a broadened signal. The physical decoupling of the photodetector from the pickup pattern allows easy customization for different applications while maintaining high analog bandwidth.

  19. The analysis of conductive solid samples by r.f. capacitively coupled plasma at atmospheric pressure.

    PubMed

    Anghel, S D; Frentiu, T; Rusu, A M; Bese, L; Cordos, E A

    1996-06-01

    A radiofrequency capacitively coupled plasma (rf CCP) with tip-ring electrode geometry has been used for the analysis of Al, Co, Cr, Cu, Mn, Mo, Ni, and V in low and medium alloyed steel. The sample is used as one of the electrodes of the plasma torch. The influence of plasma power, argon flow rate and distance between the electrodes on the analytical signals has been studied. The limits of detection are in the range of 0.001 to 0.048%. The dynamic range is three orders of magnitude.

  20. Externally controlled local magnetic field in a conducting mesoscopic ring coupled to a quantum wire

    SciTech Connect

    Maiti, Santanu K.

    2015-01-14

    In the present work, the possibility of regulating local magnetic field in a quantum ring is investigated theoretically. The ring is coupled to a quantum wire and subjected to an in-plane electric field. Under a finite bias voltage across the wire a net circulating current is established in the ring which produces a strong magnetic field at its centre. This magnetic field can be tuned externally in a wide range by regulating the in-plane electric field, and thus, our present system can be utilized to control magnetic field at a specific region. The feasibility of this quantum system in designing spin-based quantum devices is also analyzed.

  1. Myofibroblasts Electrotonically Coupled to Cardiomyocytes Alter Conduction: Insights at the Cellular Level from a Detailed In silico Tissue Structure Model

    PubMed Central

    Jousset, Florian; Maguy, Ange; Rohr, Stephan; Kucera, Jan P.

    2016-01-01

    Fibrotic myocardial remodeling is typically accompanied by the appearance of myofibroblasts (MFBs). In vitro, MFBs were shown to slow conduction and precipitate ectopic activity following gap junctional coupling to cardiomyocytes (CMCs). To gain further mechanistic insights into this arrhythmogenic MFB-CMC crosstalk, we performed numerical simulations in cell-based high-resolution two-dimensional tissue models that replicated experimental conditions. Cell dimensions were determined using confocal microscopy of single and co-cultured neonatal rat ventricular CMCs and MFBs. Conduction was investigated as a function of MFB density in three distinct cellular tissue architectures: CMC strands with endogenous MFBs, CMC strands with coating MFBs of two different sizes, and CMC strands with MFB inserts. Simulations were performed to identify individual contributions of heterocellular gap junctional coupling and of the specific electrical phenotype of MFBs. With increasing MFB density, both endogenous and coating MFBs slowed conduction. At MFB densities of 5–30%, conduction slowing was most pronounced in strands with endogenous MFBs due to the MFB-dependent increase in axial resistance. At MFB densities >40%, very slow conduction and spontaneous activity was primarily due to MFB-induced CMC depolarization. Coating MFBs caused non-uniformities of resting membrane potential, which were more prominent with large than with small MFBs. In simulations of MFB inserts connecting two CMC strands, conduction delays increased with increasing insert lengths and block appeared for inserts >1.2 mm. Thus, electrophysiological properties of engineered CMC-MFB co-cultures depend on MFB density, MFB size and their specific positioning in respect to CMCs. These factors may influence conduction characteristics in the heterocellular myocardium. PMID:27833567

  2. Myofibroblasts Electrotonically Coupled to Cardiomyocytes Alter Conduction: Insights at the Cellular Level from a Detailed In silico Tissue Structure Model.

    PubMed

    Jousset, Florian; Maguy, Ange; Rohr, Stephan; Kucera, Jan P

    2016-01-01

    Fibrotic myocardial remodeling is typically accompanied by the appearance of myofibroblasts (MFBs). In vitro, MFBs were shown to slow conduction and precipitate ectopic activity following gap junctional coupling to cardiomyocytes (CMCs). To gain further mechanistic insights into this arrhythmogenic MFB-CMC crosstalk, we performed numerical simulations in cell-based high-resolution two-dimensional tissue models that replicated experimental conditions. Cell dimensions were determined using confocal microscopy of single and co-cultured neonatal rat ventricular CMCs and MFBs. Conduction was investigated as a function of MFB density in three distinct cellular tissue architectures: CMC strands with endogenous MFBs, CMC strands with coating MFBs of two different sizes, and CMC strands with MFB inserts. Simulations were performed to identify individual contributions of heterocellular gap junctional coupling and of the specific electrical phenotype of MFBs. With increasing MFB density, both endogenous and coating MFBs slowed conduction. At MFB densities of 5-30%, conduction slowing was most pronounced in strands with endogenous MFBs due to the MFB-dependent increase in axial resistance. At MFB densities >40%, very slow conduction and spontaneous activity was primarily due to MFB-induced CMC depolarization. Coating MFBs caused non-uniformities of resting membrane potential, which were more prominent with large than with small MFBs. In simulations of MFB inserts connecting two CMC strands, conduction delays increased with increasing insert lengths and block appeared for inserts >1.2 mm. Thus, electrophysiological properties of engineered CMC-MFB co-cultures depend on MFB density, MFB size and their specific positioning in respect to CMCs. These factors may influence conduction characteristics in the heterocellular myocardium.

  3. Solid-state synthesis of a conducting polythiophene via an unprecedented heterocyclic coupling reaction.

    PubMed

    Meng, Hong; Perepichka, Dmitrii F; Bendikov, Michael; Wudl, Fred; Pan, Grant Z; Yu, Wenjiang; Dong, Wenjian; Brown, Stuart

    2003-12-10

    Prolonged storage ( approximately 2 years) or gentle heating (50-80 degrees C) of crystalline 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) affords a highly conducting, bromine-doped poly(3,4-ethylenedioxythiophene) (PEDOT), as confirmed by solid-state NMR, FTIR, CV, and vis-NIR spectroscopies. The novel solid-state polymerization (SSP) does not occur for 2,5-dichloro-3,4-ethylenedioxythiophene (DCEDOT), and requires a much higher temperature (>130 degrees C) for 2,5-diiodo-3,4-ethylenedioxythiophene (DIEDOT). X-ray structural analysis of the above dihalothiophenes reveals short Hal.Hal distances between adjacent molecules in DBEDOT and DIEDOT, but not in DCEDOT. The polymerization may also occur in the melt but is significantly slower and leads to poorly conductive material. Detailed studies of the reaction were performed using ESR, DSC, microscopy, and gravimetric analyses. SSP starts on crystal defect sites; it is exothermic by 14 kcal/mol and requires activation energy of approximately 26 kcal/mol (for DBEDOT). The temperature dependence of the conductivity of SSP-PEDOT (sigma(rt) = 20-80 S/cm) reveals a slight thermal activation. It can be further increased by a factor of 2 by doping with iodine. Using this approach, thin films of PEDOT with conductivity as high as 20 S/cm were fabricated on insulating flexible plastic surfaces.

  4. The circular current in a conducting mesoscopic ring with coupled quantum dot

    NASA Astrophysics Data System (ADS)

    Bo, Zhou

    2016-11-01

    In this paper, we investigate the circular current in the metallic ring coupled with two QDs connected with two ferromagnetic leads with the in-plane electric field ξ which is perpendicular to the wire applied to the ring by using the non-equilibrium Green's function technique. We find that in this systems the circular current in the ring can be tuned by the voltages between left and right electrodes, the temperature, the spin polarization, and the energy of the QDs and the electric field ɛ. With these parameters varied, the values and direction of the circular current can be controlled, so we can control the values and the directions of the magnetic field produced at the ring center. In addition, there also has the function of spin filter in the P and has the function of suppression of the circular current for large 𝒫 of the AP. So this structure has potential applications in designing spin-based quantum devices.

  5. Fully-coupled engineering and mesoscale simulations of thermal conductivity in UO2 fuel using an implicit multiscale approach

    SciTech Connect

    Michael Tonks; Derek Gaston; Cody Permann; Paul Millett; Glen Hansen; Chris Newman

    2009-08-01

    Reactor fuel performance is sensitive to microstructure changes during irradiation (such as fission gas and pore formation). This study proposes an approach to capture microstructural changes in the fuel by a two-way coupling of a mesoscale phase field irradiation model to an engineering scale, finite element calculation. This work solves the multiphysics equation system at the engineering-scale in a parallel, fully-coupled, fully-implicit manner using a preconditioned Jacobian-free Newton Krylov method (JFNK). A sampling of the temperature at the Gauss points of the coarse scale is passed to a parallel sequence of mesoscale calculations within the JFNK function evaluation phase of the calculation. The mesoscale thermal conductivity is calculated in parallel, and the result is passed back to the engineering-scale calculation. As this algorithm is fully contained within the JFNK function evaluation, the mesoscale calculation is nonlinearly consistent with the engineering-scale calculation. Further, the action of the Jacobian is also consistent, so the composite algorithm provides the strong nonlinear convergence properties of Newton's method. The coupled model using INL's \\bison\\ code demonstrates quadratic nonlinear convergence and good parallel scalability. Initial results predict the formation of large pores in the hotter center of the pellet, but few pores on the outer circumference. Thus, the thermal conductivity is is reduced in the center of the pellet, leading to a higher internal temperature than that in an unirradiated pellet.

  6. Contactless processing of SiGe-melts in EML under reduced gravity.

    PubMed

    Luo, Yuansu; Damaschke, Bernd; Schneider, Stephan; Lohöfer, Georg; Abrosimov, Nikolay; Czupalla, Matthias; Samwer, Konrad

    2016-01-01

    The processing of semiconductors based on electromagnetic levitation is a challenge, because this kind of materials shows a poor electrical conductivity. Here, we report the results of measurements of the thermophysical properties obtained recently from highly doped semiconductors Si1-x Ge x under microgravity conditions in the framework of parabola flight campaigns. Due to the limited time of about 20 s of microgravity especially Ge-rich samples with low melting temperatures were investigated. The measurements were performed contactlessly by video techniques with subsequent digital image processing. Linear and volume thermal expansion coefficients were measured hereby from image data. An anomaly of volume changes near the solidus temperature is visible. Viscosity and surface tension were determined by the oscillating drop technique using optic and electronic data. It was observed that the alloying of Si into Ge increases the surface tension of the melts. The viscosity is following an Arrhenius equation and shows a crossover temperature which separates simple liquid at high temperatures from cooperative liquid at low temperatures.

  7. A gradiometric version of contactless inductive flow tomography: theory and first applications.

    PubMed

    Ratajczak, Matthias; Wondrak, Thomas; Stefani, Frank

    2016-06-28

    The contactless inductive flow tomography (CIFT) is a measurement technique that allows reconstructing the flow of electrically conducting fluids by measuring the flow-induced perturbations of one or various applied magnetic fields and solving the underlying inverse problem. One of the most promising application fields of CIFT is the continuous casting of steel, for which the online monitoring of the flow in the mould would be highly desirable. In previous experiments at a small-scale model of continuous casting, CIFT has been applied to various industrially relevant problems, including the sudden changes of flow structures in case of argon injection and the influence of a magnetic stirrer at the submerged entry nozzle. The application of CIFT in the presence of electromagnetic brakes, which are widely used to stabilize the flow in the mould, has turned out to be more challenging due to the extreme dynamic range between the strong applied brake field and the weak flow-induced perturbations of the measuring field. In this paper, we present a gradiometric version of CIFT, relying on gradiometric field measurements, that is capable to overcome those problems and which seems, therefore, a promising candidate for applying CIFT in the steel casting industry. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  8. A gradiometric version of contactless inductive flow tomography: theory and first applications

    PubMed Central

    Wondrak, Thomas; Stefani, Frank

    2016-01-01

    The contactless inductive flow tomography (CIFT) is a measurement technique that allows reconstructing the flow of electrically conducting fluids by measuring the flow-induced perturbations of one or various applied magnetic fields and solving the underlying inverse problem. One of the most promising application fields of CIFT is the continuous casting of steel, for which the online monitoring of the flow in the mould would be highly desirable. In previous experiments at a small-scale model of continuous casting, CIFT has been applied to various industrially relevant problems, including the sudden changes of flow structures in case of argon injection and the influence of a magnetic stirrer at the submerged entry nozzle. The application of CIFT in the presence of electromagnetic brakes, which are widely used to stabilize the flow in the mould, has turned out to be more challenging due to the extreme dynamic range between the strong applied brake field and the weak flow-induced perturbations of the measuring field. In this paper, we present a gradiometric version of CIFT, relying on gradiometric field measurements, that is capable to overcome those problems and which seems, therefore, a promising candidate for applying CIFT in the steel casting industry. This article is part of the themed issue ‘Supersensing through industrial process tomography’. PMID:27185963

  9. Coupled integral equation solution for two dimensional bistatic TE scatter from a conducting cavity-backed infinite plane

    NASA Astrophysics Data System (ADS)

    Fairbanks, Ronald R.

    1988-12-01

    The purpose of this thesis is to determine the scattered electromagnetic fields and radar cross section from a two-dimensional cavity in a perfectly electric conducting infinite plane. This is accomplished by deriving a coupled set of Fredholm integral equations of the second kind. A set of integral equations outside the cavity and a set of integral equations inside the cavity are coupled together at the interface. The Fredholm integral equations of the second kind for the outside of the cavity use a Green's function with Neumann boundry conditions to avoid an integration over the infinite plane for a transverse electric incident plane wave. An example problem is introduced and numerically solved to test the application of the newly derived equations.

  10. Self-diffusion, conductivity, and long-wavelength plasma oscillations in strongly coupled two-component plasmas

    NASA Astrophysics Data System (ADS)

    Sjogren, L.; Hansen, J. P.; Pollock, E. L.

    1981-09-01

    The autocorrelation functions of the microscopic electric current J(t) and the electron velocity Z2(t) are calculated for strongly coupled semiclassical two-component plasmas. The corresponding memory functions are expressed in terms of mode-coupling integrals involving density- and energy-correlation functions in the framework of a microscopic kinetic theory which preserves the exact statics. The theory is applied to weakly degenerate hydrogen and carbon plasmas for values of the plasma parameter of order 1. The resulting correlation functions J(t) and Z2(t) and their integrals, the electrical conductivity, and the electron self-diffusion constant, agree reasonably well with the molecular dynamics data of Hansen and McDonald and with additional simulation results presented here.

  11. Contactless ultrasonic energy transfer for wireless systems: acoustic-piezoelectric structure interaction modeling and performance enhancement

    NASA Astrophysics Data System (ADS)

    Shahab, S.; Erturk, A.

    2014-12-01

    There are several applications of wireless electronic components with little or no ambient energy available to harvest, yet wireless battery charging for such systems is still of great interest. Example applications range from biomedical implants to sensors located in hazardous environments. Energy transfer based on the propagation of acoustic waves at ultrasonic frequencies is a recently explored alternative that offers increased transmitter-receiver distance, reduced loss and the elimination of electromagnetic fields. As this research area receives growing attention, there is an increased need for fully coupled model development to quantify the energy transfer characteristics, with a focus on the transmitter, receiver, medium, geometric and material parameters. We present multiphysics modeling and case studies of the contactless ultrasonic energy transfer for wireless electronic components submerged in fluid. The source is a pulsating sphere, and the receiver is a piezoelectric bar operating in the 33-mode of piezoelectricity with a fundamental resonance frequency above the audible frequency range. The goal is to quantify the electrical power delivered to the load (connected to the receiver) in terms of the source strength. Both the analytical and finite element models have been developed for the resulting acoustic-piezoelectric structure interaction problem. Resistive and resistive-inductive electrical loading cases are presented, and optimality conditions are discussed. Broadband power transfer is achieved by optimal resistive-reactive load tuning for performance enhancement and frequency-wise robustness. Significant enhancement of the power output is reported due to the use of a hard piezoelectric receiver (PZT-8) instead of a soft counterpart (PZT-5H) as a result of reduced material damping. The analytical multiphysics modeling approach given in this work can be used to predict and optimize the coupled system dynamics with very good accuracy and dramatically

  12. Tight coupling of rubidium conductance and inactivation in human KCNQ1 potassium channels.

    PubMed

    Seebohm, Guiscard; Sanguinetti, Michael C; Pusch, Michael

    2003-10-15

    KCNQ1 K+ channels in humans are important for repolarization of cardiac action potentials and for K+ secretion in the inner ear. The pore-forming channel subunits form heteromeric complexes with small regulatory subunits of the KCNE family, in particular with KCNE1 to form channels that conduct a slow delayed rectifier K+ current, IKs. This association leads to alteration of biophysical properties, including a slowing of activation, a suppression of inactivation and an increase of the apparent single-channel conductance. In addition, inward Rb+ currents conducted by homomeric KCNQ1 channels are about threefold larger than K+ currents, whereas heteromeric KCNQ1-KCNE1 channels have smaller inward Rb+ currents compared to K+ currents. We determined inactivation properties and compared K+ vs. Rb+ inward currents for channels formed by co-assembly of KCNQ1 with KCNE1, KCNE3 and KCNE5, and for homomeric KCNQ1 channels with point mutations in the pore helix S5 or S6 transmembrane domains. Several of the channels with point mutations eliminated the apparent inactivation of KCNQ1, as described previously (Seebohm et al. 2001). We found that the extent of inactivation and the ratio of Rb+/K+ currents were positively correlated. Since the effect of Rb+ on the current size has been shown previously to be related to a fast 'flickery' process, our results suggest that inactivation of KCNQ1 channels is related to a fast flicker of the open channel. A kinetic model incorporating two open states, no explicit inactivated state and a fast flicker that is different for the two open states is able to account for the apparent inactivation and the correlation of inactivation and large Rb+ currents. We conclude that an association between KCNQ1 and KCNE subunits or removal of inactivation by mutation of KCNQ1 stabilizes the open conformation of the pore principally by altering an interaction between the pore helix and the selectivity filter and with S5/S6 domains.

  13. Transition of temperature coefficient of conductance in weakly coupled gold nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Guan, Changrong; Sun, Jinling; Peng, Lianmao; Liao, Jianhui

    2014-12-01

    A unique positive-to-negative transition of temperature coefficient of conductance (TCC) was observed in self-assembled close-packed Au nanoparticle (AuNP) arrays. The transition of TCC can be interpreted properly with a diffusive hopping model, in which the Coulomb charging energy Ea plays a significant role. Two parameters of AuNP arrays, the nearest neighboring number and the particle core size, have been varied to tune Ea. Our data show that the positive-to-negative transitions of TCC are relevant to both parameters, which confirms the validity of the diffusive hopping model.

  14. Influence of the Asian Monsoon on the Couplings between Stomatal Conductance and Micrometeorological Variables of Forest Ecosystems in East Asia

    NASA Astrophysics Data System (ADS)

    Kang, M.; Ruddell, B. L.; Yun, J.; Kim, S.; Cho, C. H.; Chun, J. H.; Hirano, T.; Yu, G.; Kim, J.

    2014-12-01

    The performance of land surface models deteriorates under extreme climate conditions (e.g., drought) because of fundamental changes in the system structure. The ecohydrologic system is complex system in which the relationships between the variables in the system change depending on time and system state. A monsoon introduces a profound alteration in process which may define a shift in the system state. Transpiration in the ecohydrologic system is an important point of contact between water, carbon, and energy exchange subsystems, and the stomatal conductance is one of the key factors which controls transpiration. We utilized transfer entropy in a dynamical process network application to define changes in system state by observing changes in the couplings between this system's carbon, water, and energy subsystems. We quantified the transfer entropy from the micrometeorological variables of a flux tower i.e., solar radiation, vapor pressure deficit, air temperature, and soil water content to the stomatal conductance for the five forest ecosystems in East Asia. The strength of this coupling increased significantly during and after the monsoon. Based on the result, we are modifying the parameterization of stomatal conductance to integrate the biological adaptation to the monsoon into the simulation of transpiration in a land surface model. Acknowledgment. This research was supported by the Korea Meteorological Administration Research and Development Program under Grant CATER 2014-3030.

  15. Thermomechanically coupled conduction mode laser welding simulations using smoothed particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Hu, Haoyue; Eberhard, Peter

    2016-10-01

    Process simulations of conduction mode laser welding are performed using the meshless Lagrangian smoothed particle hydrodynamics (SPH) method. The solid phase is modeled based on the governing equations in thermoelasticity. For the liquid phase, surface tension effects are taken into account to simulate the melt flow in the weld pool, including the Marangoni force caused by a temperature-dependent surface tension gradient. A non-isothermal solid-liquid phase transition with the release or absorption of additional energy known as the latent heat of fusion is considered. The major heat transfer through conduction is modeled, whereas heat convection and radiation are neglected. The energy input from the laser beam is modeled as a Gaussian heat source acting on the initial material surface. The developed model is implemented in Pasimodo. Numerical results obtained with the model are presented for laser spot welding and seam welding of aluminum and iron. The change of process parameters like welding speed and laser power, and their effects on weld dimensions are investigated. Furthermore, simulations may be useful to obtain the threshold for deep penetration welding and to assess the overall welding quality. A scalability and performance analysis of the implemented SPH algorithm in Pasimodo is run in a shared memory environment. The analysis reveals the potential of large welding simulations on multi-core machines.

  16. Ultrafast-Contactless Flash Sintering using Plasma Electrodes

    NASA Astrophysics Data System (ADS)

    Saunders, Theo; Grasso, Salvatore; Reece, Michael J.

    2016-06-01

    This paper presents a novel derivative of flash sintering, in which contactless flash sintering (CFS) is achieved using plasma electrodes. In this setup, electrical contact with the sample to be sintered is made by two arc plasma electrodes, one on either side, allowing current to pass through the sample. This opens up the possibility of continuous throughput flash sintering. Preheating, a usual precondition for flash sintering, is provided by the arc electrodes which heat the sample to 1400 °C. The best results were produced with pre-compacted samples (bars 1.8 mm thick) of pure B4C (discharge time 2s, current 4A) and SiC:B4C 50 wt% (3s at 6A), which were fully consolidated under a heating rate approaching 20000 °C/min. For the composite a cylindrical volume of 14 mm3 was sintered to full density with limited grain growth.

  17. Ultrafast-Contactless Flash Sintering using Plasma Electrodes

    PubMed Central

    Saunders, Theo; Grasso, Salvatore; Reece, Michael J.

    2016-01-01

    This paper presents a novel derivative of flash sintering, in which contactless flash sintering (CFS) is achieved using plasma electrodes. In this setup, electrical contact with the sample to be sintered is made by two arc plasma electrodes, one on either side, allowing current to pass through the sample. This opens up the possibility of continuous throughput flash sintering. Preheating, a usual precondition for flash sintering, is provided by the arc electrodes which heat the sample to 1400 °C. The best results were produced with pre-compacted samples (bars 1.8 mm thick) of pure B4C (discharge time 2s, current 4A) and SiC:B4C 50 wt% (3s at 6A), which were fully consolidated under a heating rate approaching 20000 °C/min. For the composite a cylindrical volume of 14 mm3 was sintered to full density with limited grain growth. PMID:27273255

  18. Ultrafast-Contactless Flash Sintering using Plasma Electrodes.

    PubMed

    Saunders, Theo; Grasso, Salvatore; Reece, Michael J

    2016-06-08

    This paper presents a novel derivative of flash sintering, in which contactless flash sintering (CFS) is achieved using plasma electrodes. In this setup, electrical contact with the sample to be sintered is made by two arc plasma electrodes, one on either side, allowing current to pass through the sample. This opens up the possibility of continuous throughput flash sintering. Preheating, a usual precondition for flash sintering, is provided by the arc electrodes which heat the sample to 1400 °C. The best results were produced with pre-compacted samples (bars 1.8 mm thick) of pure B4C (discharge time 2s, current 4A) and SiC:B4C 50 wt% (3s at 6A), which were fully consolidated under a heating rate approaching 20000 °C/min. For the composite a cylindrical volume of 14 mm(3) was sintered to full density with limited grain growth.

  19. Tight coupling of rubidium conductance and inactivation in human KCNQ1 potassium channels

    PubMed Central

    Seebohm, Guiscard; Sanguinetti, Michael C; Pusch, Michael

    2003-01-01

    KCNQ1 K+ channels in humans are important for repolarization of cardiac action potentials and for K+ secretion in the inner ear. The pore-forming channel subunits form heteromeric complexes with small regulatory subunits of the KCNE family, in particular with KCNE1 to form channels that conduct a slow delayed rectifier K+ current, Iks. This association leads to alteration of biophysical properties, including a slowing of activation, a suppression of inactivation and an increase of the apparent single-channel conductance. In addition, inward Rb+ currents conducted by homomeric KCNQ1 channels are about threefold larger than K+ currents, whereas heteromeric KCNQ1-KCNE1 channels have smaller inward Rb+ currents compared to K+ currents. We determined inactivation properties and compared K+vs. Rb+ inward currents for channels formed by co-assembly of KCNQ1 with KCNE1, KCNE3 and KCNE5, and for homomeric KCNQ1 channels with point mutations in the pore helix S5 or S6 transmembrane domains. Several of the channels with point mutations eliminated the apparent inactivation of KCNQ1, as described previously (Seebohm et al. 2001). We found that the extent of inactivation and the ratio of Rb+/K+ currents were positively correlated. Since the effect of Rb+ on the current size has been shown previously to be related to a fast ‘flickery’ process, our results suggest that inactivation of KCNQ1 channels is related to a fast flicker of the open channel. A kinetic model incorporating two open states, no explicit inactivated state and a fast flicker that is different for the two open states is able to account for the apparent inactivation and the correlation of inactivation and large Rb+ currents. We conclude that an association between KCNQ1 and KCNE subunits or removal of inactivation by mutation of KCNQ1 stabilizes the open conformation of the pore principally by altering an interaction between the pore helix and the selectivity filter and with S5/S6 domains. PMID:14561821

  20. New understanding of three-dimensional Ionospheric conductivities and application to global analysis of magnetosphere-ionosphere-thermosphere coupling

    NASA Astrophysics Data System (ADS)

    McGranaghan, R. M.; Knipp, D.; Matsuo, T.

    2016-12-01

    System science has emerged as a promising approach to understanding the complex, coupled magnetosphere-ionosphere-thermosphere (MIT) environment. Fundamental to the success of system science in the MIT system is the ability to describe coupling phenomena, especially in the polar regions where the effects are most direct. This coupling is controlled by the ionospheric conductivity, a historically uncertain and poorly specified parameter. Advances in data analysis techniques now enable us to reconsider of our understanding and modeling of this critical parameter, particularly the assumption that the ionosphere is adequately described as a two-dimensional spherical shell. We present results of two powerful data analysis techniques applied to global-scale three-dimensional (3-D) ionospheric conductivities using Defense Meteorological Satellite Program (DMSP) data: 1) empirical orthogonal function (EOF) analysis, and 2) assimilative reconstruction via optimal interpolation (OI). With the EOF analysis we identify three primary modes of 3-D variability related to ionospheric footprints of the quiet and disturbed geospace environment [McGranaghan et al., 2016]: 1) perturbation of the quasi-permanent auroral oval; 2) differing projections of electron precipitation during southward and northward interplanetary magnetic field; and 3) a likely imprint of variation in Alfvénic Poynting flux deposition. The EOFs are then used to inform an OI scheme to reconstruct complete distributions of ionospheric conductivities and their associated uncertainties. We evaluate the reconstructions against extensive available ionospheric electrodynamics data, including auroral imagery, AMPERE field-aligned currents, and volumetric information from the Poker Flat Incoherent Scatter Radar (PFISR). Our results can be used to calculate the 3-D distribution of Joule heating in the E-Region ionosphere. Our findings underscore the importance of analyzing the ionosphere in 3-D and demonstrate the

  1. Proton conducting sodium alginate electrolyte laterally coupled low-voltage oxide-based transistors

    NASA Astrophysics Data System (ADS)

    Liu, Yang Hui; Qiang Zhu, Li; Shi, Yi; Wan, Qing

    2014-03-01

    Solution-processed sodium alginate electrolyte film shows a high proton conductivity of ˜5.5 × 10-3 S/cm and a high lateral electric-double-layer (EDL) capacitance of ˜2.0 μF/cm2 at room temperature with a relative humidity of 57%. Low-voltage in-plane-gate indium-zinc-oxide-based EDL transistors laterally gated by sodium alginate electrolytes are fabricated on glass substrates. The field-effect mobility, current ON/OFF ratio, and subthreshold swing of such EDL transistors are estimated to be 4.2 cm2 V-1 s-1, 2.8 × 106, and 130 mV/decade, respectively. At last, a low-voltage driven resistor-load inverter is also demonstrated. Such in-plane-gate EDL transistors have potential applications in portable electronics and low-cost biosensors.

  2. Contactless electroreflectance studies of surface potential barrier for N- and Ga-face epilayers grown by molecular beam epitaxy

    SciTech Connect

    Kudrawiec, R.; Janicki, L.; Gladysiewicz, M.; Misiewicz, J.; Cywinski, G.; Boćkowski, M.; Muzioł, G.

    2013-07-29

    Two series of N- and Ga-face GaN Van Hoof structures were grown by plasma-assisted molecular beam epitaxy to study the surface potential barrier by contactless electroreflectance (CER). A clear CER resonance followed by strong Franz-Keldysh oscillation of period varying with the thickness of undoped GaN layer was observed for these structures. This period was much shorter for N-polar structures that means smaller surface potential barrier in these structures than in Ga-polar structures. From the analysis of built-in electric field it was determined that the Fermi-level is located 0.27 ± 0.05 and 0.60 ± 0.05 eV below the conduction band for N- and Ga-face GaN surface, respectively.

  3. Large electronic sputtering yield of nanodimensional Au thin films: Dominant role of thermal conductivity and electron phonon coupling factor

    NASA Astrophysics Data System (ADS)

    Singh, Udai B.; Pannu, Compesh; Agarwal, Dinesh C.; Ojha, Sunil; Khan, Saif A.; Ghosh, Santanu; Avasthi, Devesh K.

    2017-03-01

    Detailed experiments and theoretical calculations on electronic sputtering of Au thin films (5-200 nm) on a quartz substrate are performed, revealing unusually large electronic sputtering, dependent on the thickness of the films. The dependence of electronic thermal conductivity (κe), electron-phonon coupling factor (g), and lattice thermal conductivity (κa) on the effective electron mean free path is taken into account in the thermal spike calculation for nanodimensional systems to elucidate the combined effect of the thickness and grain size on the electronic sputtering yield. The thermal spike simulation with refined parameters for nanodimensional systems gives a better explanation of the electronic sputtering process with a very good correlation between the experimental and theoretical yields than that of the thermal spike model with bulk parameters.

  4. Transient conductive, radiative heat transfer coupled with moisture transport in attic insulations

    NASA Astrophysics Data System (ADS)

    Gorthala, R.; Harris, K. T.; Roux, J. A.; McCarty, T. A.

    1994-01-01

    A transient, one-dimensional thermal model that incorporates combined conduction, radiation heat transfer, and moisture transport for residential attic insulations has been developed. The governing equations are the energy equation, the radiative transport equation for volumetric radiation within the insulation batt, and the species equations for bound H2O and vapor H2O. A simultaneous solution procedure with a Eulerian control volume-based finite difference method was used to solve the energy equation and the species equations. The method of discrete ordinates was used in solving the radiative transport equation. For H2O transport, both diffusion of vapor H2O and bound H2O and moisture adsorption/desorption within the insulation binder are included in the model. The experimental data measured at an occupied North Mississippi residence for R19STD (standard R19 fiberglass insulation batt without a foil radiant barrier) were used to validate the model which predicted heat fluxes for summer, spring, winter, and fall seasonal conditions. These predictions were compared with the measured heat flux data and the predictions from the dry model (without the moisture transport). Various profiles such as temperature-time histories, relative humidity time histories, spatial H2O concentrations, spatial temperatures, and spatial heat fluxes are presented to explain the overall heat transfer behavior.

  5. Proton conducting sodium alginate electrolyte laterally coupled low-voltage oxide-based transistors

    SciTech Connect

    Liu, Yang Hui; Wan, Qing; Qiang Zhu, Li; Shi, Yi

    2014-03-31

    Solution-processed sodium alginate electrolyte film shows a high proton conductivity of ∼5.5 × 10{sup −3} S/cm and a high lateral electric-double-layer (EDL) capacitance of ∼2.0 μF/cm{sup 2} at room temperature with a relative humidity of 57%. Low-voltage in-plane-gate indium-zinc-oxide-based EDL transistors laterally gated by sodium alginate electrolytes are fabricated on glass substrates. The field-effect mobility, current ON/OFF ratio, and subthreshold swing of such EDL transistors are estimated to be 4.2 cm{sup 2} V{sup −1} s{sup −1}, 2.8 × 10{sup 6}, and 130 mV/decade, respectively. At last, a low-voltage driven resistor-load inverter is also demonstrated. Such in-plane-gate EDL transistors have potential applications in portable electronics and low-cost biosensors.

  6. Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model

    SciTech Connect

    Huang, Hai; Plummer, Mitchell; Podgorney, Robert

    2013-02-01

    Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.

  7. Tunneling conductance study of a metal-superconductor junction in the presence of Rashba spin orbit coupling

    NASA Astrophysics Data System (ADS)

    Kapri, Priyadarshini; Basu, Saurabh

    2017-02-01

    The tunneling conductance for a junction device consisting of a normal metal and a singlet superconductor is studied with Rashba spin orbit coupling (RSOC) being present in the metallic lead and the interface separating the two regions via an extended Blonder-Tinkham-Klapwijk (BTK) formalism. Interesting interplay between the RSOC and a number of parameters that have experimental significance, and characterize either the junction or the superconducting leads, such as the barrier transparency, quasiparticle lifetime, Fermi wavevector mismatch, an in-plane magnetic field and their effects on the tunneling conductance are investigated in details for both a s-wave and a d-wave superconductor. In an opaque barrier, in presence of a quasiparticle lifetime, a Fermi wavevector mismatch or an external in-plane magnetic field, RSOC enhances the conductance corresponding to low biasing energies, that is, at energies lesser than the superconducting gap, while the reverse is noted for energies exceeding the magnitude of the gap. Further, there are exciting anomalies noted in the conductance spectrum for the d-wave gap which can be understood by incorporating the interplay between the superconducting gap and the angle of incident of the charge carriers.

  8. Conductance plateau due to Majorana bound state in a quantum dot coupled to a topological quantum wire

    NASA Astrophysics Data System (ADS)

    Vernek, Edson; Penteado, Poliana; Seridonio, Antonio; Egues, José C.

    2014-03-01

    The search for Majorana bound state (MBS) is topological superconductor nanowires is currently a topic of great interest. Despite the various theoretical proposals and the experimental results, the question of whether the possible signatures of MBS can be distinguished from those arising from other phenomena such as the Kondo effect is still under debate. A recent proposal for detecting MBS using a quantum dot coupled to normal two leads and to a topological quantum wire has proven to be very appropriate structure to investigate this problem. In this system, the presence of MBS in the wire is marked as a e2 / 2 h conductance through the dot. In this work we find, that the e2 / 2 h conductance peak is not per se an distinct signature of a MBS in the wire. We show instead that it results from a leaking of the Majorana state into the dot. Moreover, by gating the dot level (ɛd) far away below and above the Fermi level of the leads (ɛF), the conductance remains at e2 / 2 h . The surviving of the conductance plateau for ɛd >ɛF contrasts with Kondo effect plateau known to emerge only for ɛd <ɛF . This work is supported by FAPESP, CNPq, CAPES and FAPEMIG.

  9. Contactless Method for Electrical Characterization of Silicon-on-Insulator Materials

    NASA Astrophysics Data System (ADS)

    Okumura, Tsugunori; Eguchi, Kazuyoshi; En, Aimin; Suhara, Michihiko

    2001-09-01

    The Kelvin-probe method, in combination with surface photovoltage (SPV) measurements, is applied to the nondestructive electrical characterization of silicon-on-insulator (SOI) materials. It is shown that a simple sandwich-type electrode configuration can be used for the contactless characterization of the SOI layer, when the capacitance between the vibrating electrode and the SOI surface is much smaller than the buried-oxide (BOX) and depletion-layer series capacitances. The light-intensity dependence of the SPV gives data equivalent to common cuurent-voltage (I-V) characteristics of diodes. Thus, we call the proposed method the contactless I-V method. Lastly, we demonstrate that UV illumination is effective for applying the contactless I-V method to ultrathin SOI layers such as fully depleted SOI material.

  10. Simultaneous determination of caffeine, paracetamol, and ibuprofen in pharmaceutical formulations by high-performance liquid chromatography with UV detection and by capillary electrophoresis with conductivity detection.

    PubMed

    Cunha, Rafael R; Chaves, Sandro C; Ribeiro, Michelle M A C; Torres, Lívia M F C; Muñoz, Rodrigo A A; Dos Santos, Wallans T P; Richter, Eduardo M

    2015-05-01

    Paracetamol, caffeine and ibuprofen are found in over-the-counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ibuprofen in pharmaceutical formulations. One method is based on high-performance liquid chromatography with diode-array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high-performance liquid chromatography with diode-array detection was achieved on a C18 column (250×4.6 mm(2), 5 μm) with a gradient mobile phase comprising 20-100% acetonitrile in 40 mmol L(-1) phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused-silica capillary (40 cm length, 50 μm i.d.) using 10 mmol L(-1) 3,4-dimethoxycinnamate and 10 mmol L(-1) β-alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 μmol L(-1) by liquid chromatography and 39, 32, and 49 μmol L(-1) by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92-107% for both proposed methods.

  11. COUPLING

    DOEpatents

    Frisch, E.; Johnson, C.G.

    1962-05-15

    A detachable coupling arrangement is described which provides for varying the length of the handle of a tool used in relatively narrow channels. The arrangement consists of mating the key and keyhole formations in the cooperating handle sections. (AEC)

  12. Contactless electromodulation investigations of surface/interface electric fields in semiconductor microstructures

    SciTech Connect

    Pollak, F.H.

    1993-07-01

    This article reviews some recent experiments using contactless electromodulation techniques, i.e., photoreflectance and contactless electroreflectance, to investigate the surface/interface electric fields in (a) pseudomorphic GaAlAs/InGaAs/GaAs modulation-doped quantum well structures (including the determination of the two-dimensional electron gas density) and (b) Fermi-level pinning on n- and p-type GaAs (001) surfaces. Evidence for the reduced surface state density on p-type material will be presented from both prior and new experiments. 25 refs., 4 figs., 1 tab.

  13. Influence of high-conductivity buffer composition on field-enhanced sample injection coupled to sweeping in CE.

    PubMed

    Anres, Philippe; Delaunay, Nathalie; Vial, Jérôme; Thormann, Wolfgang; Gareil, Pierre

    2013-02-01

    The aim of this work was to clarify the mechanism taking place in field-enhanced sample injection coupled to sweeping and micellar EKC (FESI-Sweep-MEKC), with the utilization of two acidic high-conductivity buffers (HCBs), phosphoric acid or sodium phosphate buffer, in view of maximizing sensitivity enhancements. Using cationic model compounds in acidic media, a chemometric approach and simulations with SIMUL5 were implemented. Experimental design first enabled to identify the significant factors and their potential interactions. Simulation demonstrates the formation of moving boundaries during sample injection, which originate at the initial sample/HCB and HCB/buffer discontinuities and gradually change the compositions of HCB and BGE. With sodium phosphate buffer, the HCB conductivity increased during the injection, leading to a more efficient preconcentration by staking (about 1.6 times) than with phosphoric acid alone, for which conductivity decreased during injection. For the same injection time at constant voltage, however, a lower amount of analytes was injected with sodium phosphate buffer than with phosphoric acid. Consequently sensitivity enhancements were lower for the whole FESI-Sweep-MEKC process. This is why, in order to maximize sensitivity enhancements, it is proposed to work with sodium phosphate buffer as HCB and to use constant current during sample injection. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Tunneling conductance for Majorana fermions in spin-orbit coupled semiconductor-superconductor heterostructures using superconducting leads

    NASA Astrophysics Data System (ADS)

    Sharma, Girish; Tewari, Sumanta

    2016-05-01

    It has been recently pointed out that the use of a superconducting (SC) lead instead of a normal metal lead can suppress the thermal broadening effects in tunneling conductance from Majorana fermions, helping reveal the quantized conductance of 2 e2/h . In this paper we discuss the specific case of tunneling conductance with SC leads of spin-orbit coupled semiconductor-superconductor (SM-SC) heterostructures in the presence of a Zeeman field, a system which has been extensively studied both theoretically and experimentally using a metallic lead. We examine the d I /d V spectra using a SC lead for different sets of physical parameters including temperature, tunneling strength, wire length, magnetic field, and induced SC pairing potential in the SM nanowire. We conclude that in a finite wire the Majorana splitting energy Δ E , which has nontrivial dependence on these physical parameters, remains responsible for the d I /d V peak broadening, even when the temperature broadening is suppressed by the SC gap in the lead. In a finite wire the signatures of Majorana fermions with a SC lead are oscillations of quasi-Majorana peaks about bias V =±Δlead , in contrast to the case of metallic leads where such oscillations are about zero bias. Our results will be useful for analysis of future experiments on SM-SC heterostructures using SC leads.

  15. Features of the Interface Equation Coupling Thin and Thick Film Regimes in Conduction-Triggered Thermocapillary Flows

    NASA Astrophysics Data System (ADS)

    Nicolaou, Zachary; Troian, Sandra

    2015-11-01

    An attractive feature of moving boundary problems involving the coupling of adjacent thin film regimes is the simplified form of the corresponding interface equation. For interfaces subject to conduction-triggered thermocapillary forces and damping by capillary forces, the evolution equation reduces to a 4th order nonlinear PDE. The dispersion equation for linear instability of a uniform state then reduces to Type II, characterized by a vanishing growth rate at k =0, a positive k2 contribution from the driving force and a negative k4 from capillary damping. Here we generalize to a moving interface coupling thin and thick film regimes. The resulting 4th order, nonlinear integro-differential equation contains the usual form of the capillary term but a nonlocal thermocapillary term due to far field contributions from the lateral transport of conserved quantities. The dispersion equation in no longer of Type II since the destabilizing term is no longer quadratic. Despite these differences, the generalized form retains certain pleasing features which can be exploited for further analysis.

  16. Determination of ammonium in wastewaters by capillary electrophoresis on a column-coupling chip with conductivity detection.

    PubMed

    Luc, Milan; Kruk, Pavol; Masár, Marián

    2011-07-01

    Analytical potentialities of a chip-based CE in determination of ammonium in wastewaters were investigated. CZE with the electric field and/or ITP sample stacking was performed on a column-coupling (CC) chip with integrated conductivity detectors. Acetate background electrolytes (pH ∼3) including 18-crown-6-ether (18-crown-6) and tartaric acid were developed to reach rapid (in 7-8 min) CZE and ITP-CZE resolutions of ammonium from other cations (sodium, potassium, calcium and magnesium) present in wastewater samples. Under preferred working conditions (suppressed hydrodynamic flow (HDF) and EOF on the column-coupling chip), both the employed methods did provide very good repeatabilities of the migration (RSD of 0.2-0.8% for the migration time) and quantitative (RSD of 0.3-4.9% for the peak area) parameters in the model and wastewater samples. Using a 900-nL sample injection volume, LOD for ammonium were obtained at 20 and 40 μg/L concentrations in CZE and ITP-CZE separations, respectively. Very good agreements of the CZE and ITP-CZE determinations of ammonium in six untreated wastewater samples (only filtration and dilution) with the results obtained by a reference spectrometric method indicate a very good accuracy of both the CE methods presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. VAMP-associated Proteins (VAP) as Receptors That Couple Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Proteostasis with Lipid Homeostasis.

    PubMed

    Ernst, Wayne L; Shome, Kuntala; Wu, Christine C; Gong, Xiaoyan; Frizzell, Raymond A; Aridor, Meir

    2016-03-04

    Unesterified cholesterol accumulates in late endosomes in cells expressing the misfolded cystic fibrosis transmembrane conductance regulator (CFTR). CFTR misfolding in the endoplasmic reticulum (ER) or general activation of ER stress led to dynein-mediated clustering of cholesterol-loaded late endosomes at the Golgi region, a process regulated by ER-localized VAMP-associated proteins (VAPs). We hypothesized that VAPs serve as intracellular receptors that couple lipid homeostasis through interactions with two phenylalanines in an acidic track (FFAT) binding signals (found in lipid sorting and sensing proteins, LSS) with proteostasis regulation. VAPB inhibited the degradation of ΔF508-CFTR. The activity was mapped to the ligand-binding major sperm protein (MSP) domain, which was sufficient in regulating CFTR biogenesis. We identified mutations in an unstructured loop within the MSP that uncoupled VAPB-regulated CFTR biogenesis from basic interactions with FFAT. Using this information, we defined functional and physical interactions between VAPB and proteostasis regulators (ligands), including the unfolded protein response sensor ATF6 and the ER degradation cluster that included FAF1, VCP, BAP31, and Derlin-1. VAPB inhibited the degradation of ΔF508-CFTR in the ER through interactions with the RMA1-Derlin-BAP31-VCP pathway. Analysis of pseudoligands containing tandem FFAT signals supports a competitive model for VAP interactions that direct CFTR biogenesis. The results suggest a model in which VAP-ligand binding couples proteostasis and lipid homeostasis leading to observed phenotypes of lipid abnormalities in protein folding diseases.

  18. Determination of bromate in drinking water by zone electrophoresis-isotachophoresis on a column-coupling chip with conductivity detection.

    PubMed

    Bodor, Róbert; Kaniansky, Dusan; Masár, Marián; Silleová, Katarína; Stanislawski, Bernd

    2002-10-01

    The use of capillary zone electrophoresis (CZE) on-line coupled with isotachophoresis (ITP) sample pretreatment (ITP-CZE) on a poly(methylmethacrylate) chip, provided with two separation channels in the column-coupling (CC) arrangement and on-column conductivity detection sensors, to the determination of bromate in drinking water was investigated. Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the chip were suppressed and electrophoresis was a dominant transport process in the ITP-CZE separations. A high sample load capacity, linked with the use of ITP in this combination, made possible loading of the samples by a 9.2 microL sample injection channel of the chip. In addition, bromate was concentrated by a factor of 10(3) or more in the ITP stage of the separation and, therefore, its transfer to the CZE stage characterized negligible injection dispersion. This, along with a favorable electric conductivity of the carrier electrolyte solution, contributed to a 20 nmol/L (2.5 ppb) limit of detection for bromate in the CZE stage. Sample cleanup, integrated into the ITP stage, effectively complemented such a detection sensitivity and bromate could be quantified in drinking water matrices when its concentration was 80 nmol/L (10 ppb) or slightly less while the concentrations of anionic macroconstituent (chloride, sulfate, nitrate) in the loaded sample corresponding to a 2 mmol/L (70 ppm) concentration of chloride were still tolerable. The samples containing macroconstituents at higher concentrations required appropriate dilutions and, consequently, bromate in these samples could be directly determined only at proportionally higher concentrations.

  19. Ecophysiological parameters for a coupled photosynthesis and stomatal conductance model derived from eddy covariance measurements in Asia

    NASA Astrophysics Data System (ADS)

    Ueyama, M.; Ichii, K.; Kobayashi, H.; Alberto, M. C. R.; Bret-Harte, M. S.; Edgar, C.; Euskirchen, E. S.; Harazono, Y.; Hirano, T.; Hirata, R.; Ide, R.; Kosugi, Y.; Machimura, T.; Mizoguchi, Y.; Ohta, T.; Ono, K.; Saigusa, N.; Saitoh, T. M.; Takagi, K.; Takanashi, S.; Zhang, Y.

    2015-12-01

    For better understanding carbon and water vapor fluxes in Asia, ecophysiological parameters of a coupled photosynthesis and stomatal conductance big-leaf model (Farquhar et al., 1980; Ball and Berry, 1987) were inversely estimated using micrometeorological data at 48 sites in Asia. The data covered various ecosystems of arctic tundra, boreal, temperate, and tropical forests, grasslands, and croplands. We applied a global optimization method; shuffled complex evolution (SCE-UA) method (Duan et al., 1993). First stomatal conductance parameters (m and b in the Ball-Berry model) were optimized for evapotranspiration, and then photosynthetic parameters (maximum carboxylation rate at 25oC; Vcmax25) were optimized for gross primarily productivity (GPP). The canopy-scale parameters were then downscaled into the leaf-scale using a two-leaf radiative transfer models and leaf area index (LAI) by MODIS. In the presentation, we will show the spatial variability of the ecophysiological parameters in terms of environmental gradients, and ecosystem types. Implications and limitations of the synthesis will be discussed. References Ball and Berry, 1987: Progress in Photosynthesis Research, pp 221-224. Duan et al., 1993: J. Optimization Theory and Applications, 76, 501-521. Farquhar et al., 1980: Planta, 149, 78-90.

  20. Controlled calculation of the thermal conductivity for a spinon Fermi surface coupled to a U(1) gauge field

    SciTech Connect

    Freire, Hermann

    2014-10-15

    Motivated by recent transport measurements on the candidate spin-liquid phase of the organic triangular lattice insulator EtMe{sub 3}Sb[Pd(dmit){sub 2}]{sub 2}, we perform a controlled calculation of the thermal conductivity at intermediate temperatures in a spin liquid system where a spinon Fermi surface is coupled to a U(1) gauge field. The present computation builds upon the double expansion approach developed by Mross et al. (2010) for small ϵ=z{sub b}−2 (where z{sub b} is the dynamical critical exponent of the gauge field) and large number of fermionic species N. Using the so-called memory matrix formalism that most crucially does not assume the existence of well-defined quasiparticles at low energies in the system, we calculate the temperature dependence of the thermal conductivity κ of this model due to non-critical Umklapp scattering of the spinons for a finite N and small ϵ. Then we discuss the physical implications of such theoretical result in connection with the experimental data available in the literature.

  1. Coupled effects of conduction in the crystal and thermo-solutal convection in a rectangular inclined enclosure

    NASA Technical Reports Server (NTRS)

    Mennetrier, Christophe; Duval, Walter M. B.

    1990-01-01

    To date modeling of crystal growth of optoelectronic materials using Physical Vapor Transport has been limited to the study of the fluid phase. To achieve it, the equations of coupled heat, mass and momentum transfer in the gas have to be solved. The first objective of this study is to examine the effect of heat conduction in the crystal on the fluid flow in the neighborhood of the interface. Heat transfer boundary conditions on both interfaces were modified to take into account the additional heat flux between gas and solid. It is proved that heat conduction does not affect the fluid flow. In the presence of gravity, density gradients in the fluid phase generate convection responsible for the problem of a nonplanar growth of the interface. The second objective is to study systematically under one-g the different possible flows in order to solve this problem. Depending on the parameters, a diffusive mode and three convective modes (thermal, solutal and thermo-solutal) are observed. The competition between thermal and solutal convections leads to a mathematical condition which can be used to achieve a planar growth. It is proven that, under the physical conditions chosen, this mathematical condition cannot be thermodynamically satisfied.

  2. Design and implementation of a contactless multiple hand feature acquisition system

    NASA Astrophysics Data System (ADS)

    Zhao, Qiushi; Bu, Wei; Wu, Xiangqian; Zhang, David

    2012-06-01

    In this work, an integrated contactless multiple hand feature acquisition system is designed. The system can capture palmprint, palm vein, and palm dorsal vein images simultaneously. Moreover, the images are captured in a contactless manner, that is, users need not to touch any part of the device when capturing. Palmprint is imaged under visible illumination while palm vein and palm dorsal vein are imaged under near infrared (NIR) illumination. The capturing is controlled by computer and the whole process is less than 1 second, which is sufficient for online biometric systems. Based on this device, this paper also implements a contactless hand-based multimodal biometric system. Palmprint, palm vein, palm dorsal vein, finger vein, and hand geometry features are extracted from the captured images. After similarity measure, the matching scores are fused using weighted sum fusion rule. Experimental results show that although the verification accuracy of each uni-modality is not as high as that of state-of-the-art, the fusion result is superior to most of the existing hand-based biometric systems. This result indicates that the proposed device is competent in the application of contactless multimodal hand-based biometrics.

  3. Ultra-Small Reader/Writer with Multiple Contactless Interfaces on a Flexible Circuit Board

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hideaki; Ikeda, Minoru; Hosoda, Yasuhiro

    In order to incorporate the reader/writers (RWs) into mobile electronic devices, miniaturization and flexibility are required. To meet these requirements, we fabricate an ultra-small RW with multiple contactless interfaces by mounting main unit circuits inside the antenna coil and using flexible multi-layer circuit board.

  4. Label-free Isolation and Enrichment of Cells Through Contactless Dielectrophoresis

    PubMed Central

    Elvington, Elizabeth S.; Salmanzadeh, Alireza; Stremler, Mark A.; Davalos, Rafael V.

    2013-01-01

    Dielectrophoresis (DEP) is the phenomenon by which polarized particles in a non-uniform electric field undergo translational motion, and can be used to direct the motion of microparticles in a surface marker-independent manner. Traditionally, DEP devices include planar metallic electrodes patterned in the sample channel. This approach can be expensive and requires a specialized cleanroom environment. Recently, a contact-free approach called contactless dielectrophoresis (cDEP) has been developed. This method utilizes the classic principle of DEP while avoiding direct contact between electrodes and sample by patterning fluidic electrodes and a sample channel from a single polydimethylsiloxane (PDMS) substrate, and has application as a rapid microfluidic strategy designed to sort and enrich microparticles. Unique to this method is that the electric field is generated via fluidic electrode channels containing a highly conductive fluid, which are separated from the sample channel by a thin insulating barrier. Because metal electrodes do not directly contact the sample, electrolysis, electrode delamination, and sample contamination are avoided. Additionally, this enables an inexpensive and simple fabrication process. cDEP is thus well-suited for manipulating sensitive biological particles. The dielectrophoretic force acting upon the particles depends not only upon spatial gradients of the electric field generated by customizable design of the device geometry, but the intrinsic biophysical properties of the cell. As such, cDEP is a label-free technique that avoids depending upon surface-expressed molecular biomarkers that may be variably expressed within a population, while still allowing characterization, enrichment, and sorting of bioparticles. Here, we demonstrate the basics of fabrication and experimentation using cDEP. We explain the simple preparation of a cDEP chip using soft lithography techniques. We discuss the experimental procedure for characterizing

  5. Label-free isolation and enrichment of cells through contactless dielectrophoresis.

    PubMed

    Elvington, Elizabeth S; Salmanzadeh, Alireza; Stremler, Mark A; Davalos, Rafael V

    2013-09-03

    Dielectrophoresis (DEP) is the phenomenon by which polarized particles in a non-uniform electric field undergo translational motion, and can be used to direct the motion of microparticles in a surface marker-independent manner. Traditionally, DEP devices include planar metallic electrodes patterned in the sample channel. This approach can be expensive and requires a specialized cleanroom environment. Recently, a contact-free approach called contactless dielectrophoresis (cDEP) has been developed. This method utilizes the classic principle of DEP while avoiding direct contact between electrodes and sample by patterning fluidic electrodes and a sample channel from a single polydimethylsiloxane (PDMS) substrate, and has application as a rapid microfluidic strategy designed to sort and enrich microparticles. Unique to this method is that the electric field is generated via fluidic electrode channels containing a highly conductive fluid, which are separated from the sample channel by a thin insulating barrier. Because metal electrodes do not directly contact the sample, electrolysis, electrode delamination, and sample contamination are avoided. Additionally, this enables an inexpensive and simple fabrication process. cDEP is thus well-suited for manipulating sensitive biological particles. The dielectrophoretic force acting upon the particles depends not only upon spatial gradients of the electric field generated by customizable design of the device geometry, but the intrinsic biophysical properties of the cell. As such, cDEP is a label-free technique that avoids depending upon surface-expressed molecular biomarkers that may be variably expressed within a population, while still allowing characterization, enrichment, and sorting of bioparticles. Here, we demonstrate the basics of fabrication and experimentation using cDEP. We explain the simple preparation of a cDEP chip using soft lithography techniques. We discuss the experimental procedure for characterizing

  6. Kinetic coupling between electron and proton transfer in cytochrome c oxidase: simultaneous measurements of conductance and absorbance changes.

    PubMed Central

    Adelroth, P; Sigurdson, H; Hallén, S; Brzezinski, P

    1996-01-01

    Bovine heart cytochrome c oxidase is an electron-current driven proton pump. To investigate the mechanism by which this pump operates it is important to study individual electron- and proton-transfer reactions in the enzyme, and key reactions in which they are kinetically and thermodynamically coupled. In this work, we have simultaneously measured absorbance changes associated with electron-transfer reactions and conductance changes associated with protonation reactions following pulsed illumination of the photolabile complex of partly reduced bovine cytochrome c oxidase and carbon monoxide. Following CO dissociation, several kinetic phases in the absorbance changes were observed with time constants ranging from approximately 3 microseconds to several milliseconds, reflecting internal electron-transfer reactions within the enzyme. The data show that the rate of one of these electron-transfer reactions, from cytochrome a3 to a on a millisecond time scale, is controlled by a proton-transfer reaction. These results are discussed in terms of a model in which cytochrome a3 interacts electrostatically with a protonatable group, L, in the vicinity of the binuclear center, in equilibrium with the bulk through a proton-conducting pathway, which determines the rate of proton transfer (and indirectly also of electron transfer). The interaction energy of cytochrome a3 with L was determined independently from the pH dependence of the extent of the millisecond-electron transfer and the number of protons released, as determined from the conductance measurements. The magnitude of the interaction energy, 70 meV (1 eV = 1.602 x 10(-19) J), is consistent with a distance of 5-10 A between cytochrome a3 and L. Based on the recently determined high-resolution x-ray structures of bovine and a bacterial cytochrome c oxidase, possible candidates for L and a physiological role for L are discussed. PMID:8901574

  7. Accelerating bioelectric functional development of neural stem cells by graphene coupling: Implications for neural interfacing with conductive materials.

    PubMed

    Guo, Rongrong; Zhang, Shasha; Xiao, Miao; Qian, Fuping; He, Zuhong; Li, Dan; Zhang, Xiaoli; Li, Huawei; Yang, Xiaowei; Wang, Ming; Chai, Renjie; Tang, Mingliang

    2016-11-01

    In order to govern cell-specific behaviors in tissue engineering for neural repair and regeneration, a better understanding of material-cell interactions, especially the bioelectric functions, is extremely important. Graphene has been reported to be a potential candidate for use as a scaffold and neural interfacing material. However, the bioelectric evolvement of cell membranes on these conductive graphene substrates remains largely uninvestigated. In this study, we used a neural stem cell (NSC) model to explore the possible changes in membrane bioelectric properties - including resting membrane potentials and action potentials - and cell behaviors on graphene films under both proliferation and differentiation conditions. We used a combination of single-cell electrophysiological recordings and traditional cell biology techniques. Graphene did not affect the basic membrane electrical parameters (capacitance and input resistance), but resting membrane potentials of cells on graphene substrates were more strongly negative under both proliferation and differentiation conditions. Also, NSCs and their progeny on graphene substrates exhibited increased firing of action potentials during development compared to controls. However, graphene only slightly affected the electric characterizations of mature NSC progeny. The modulation of passive and active bioelectric properties on the graphene substrate was accompanied by enhanced NSC differentiation. Furthermore, spine density, synapse proteins expressions and synaptic activity were all increased in graphene group. Modeling of the electric field on conductive graphene substrates suggests that the electric field produced by the electronegative cell membrane is much higher on graphene substrates than that on control, and this might explain the observed changes of bioelectric development by graphene coupling. Our results indicate that graphene is able to accelerate NSC maturation during development, especially with regard to

  8. Application of lateral photovoltage towards contactless light beam induced current measurements and its dependence on the finite beam size

    SciTech Connect

    Abhale, Atul Prakash; Rao, K. S. R. Koteswara

    2014-07-15

    The nature of the signal due to light beam induced current (LBIC) at the remote contacts is verified as a lateral photovoltage for non-uniformly illuminated planar p-n junction devices; simulation and experimental results are presented. The limitations imposed by the ohmic contacts are successfully overcome by the introduction of capacitively coupled remote contacts, which yield similar results without any significant loss in the estimated material and device parameters. It is observed that the LBIC measurements introduce artefacts such as shift in peak position with increasing laser power. Simulation of LBIC signal as a function of characteristic length L{sub c} of photo-generated carriers and for different beam diameters has resulted in the observed peak shifts, thus attributed to the finite size of the beam. Further, the idea of capacitively coupled contacts has been extended to contactless measurements using pressure contacts with an oxidized aluminium electrodes. This technique avoids the contagious sample processing steps, which may introduce unintentional defects and contaminants into the material and devices under observation. Thus, we present here, the remote contact LBIC as a practically non-destructive tool in the evaluation of device parameters and welcome its use during fabrication steps.

  9. Coupling of conduction electrons to two-level systems formed by hydrogen: a scattering approach.

    PubMed

    Nagy, I; Zawadowski, A

    2009-04-29

    An effective Hamiltonian for a two-level system (TLS) which could model the interaction between a tunneling proton and the conduction electrons of a metal is investigated in a comparative way. In the conventional first-order Born approximation with plane waves, and for small-distance displacement of the tunneling particle, a simple correlation between the atomic motion and angular momentum change of the scattering electron is deduced. For such a displacement, and within a distorted wave Born approximation for initial and final states, the change in the scattering amplitude is expressed via bounded trigonometric functions of the corresponding difference of scattering phase shifts. The numerical value of this amplitude change is analyzed in the framework of a self-consistent screening description for an impurity embedding in a paramagnetic electron gas. The coupling thus obtained of the tunneling proton to a homogeneous electron gas is too weak to be in the range required for realization of the two-channel Kondo effect.

  10. Measurement of Nitrogen Mustard Degredation Products by Poly(dimethylsiloxane) Microchip Electrophoresis with Contactless Conductivity Detection

    EPA Science Inventory

    The potential risk of human exposure from an accidental or intentional release of CWAs into a civilian population continues to drive the need for screening and monitoring techniques for these compounds. In particular, rapid and reliable methods for detecting CWAs such as the nitr...

  11. Measurement of Nitrogen Mustard Degredation Products by Poly(dimethylsiloxane) Microchip Electrophoresis with Contactless Conductivity Detection

    EPA Science Inventory

    The potential risk of human exposure from an accidental or intentional release of CWAs into a civilian population continues to drive the need for screening and monitoring techniques for these compounds. In particular, rapid and reliable methods for detecting CWAs such as the nitr...

  12. Contactless conductivity detector for determination of degree of esterification of citrus pectin

    USDA-ARS?s Scientific Manuscript database

    After removal of soluble sugars and other compounds by washing, citrus peel is largely composed of pectin, cellulose and hemicellulose. In order to utilize the greatest amount of citrus peel product, it would appear reasonable that one or all three of these polysaccharides be converted to a useful m...

  13. Highly sensitive contactless conductivity microchips based on concentric electrodes for flow analysis.

    PubMed

    Lima, Renato S; Piazzetta, Maria H O; Gobbi, Angelo L; Segato, Thiago P; Cabral, Murilo F; Machado, Sergio A S; Carrilho, Emanuel

    2013-12-18

    In this communication, we describe for the first time the integration of concentric electrodes (wrapping around the microchannel) in microchips. The use of such electrodes has been shown to be effective towards improvement of the sensitivity and detectability in pressure-driven flow platforms incorporating C(4)D.

  14. Contactless conductivity: an HPLC method to analyze degree of methylation of pectin

    USDA-ARS?s Scientific Manuscript database

    After removal of soluble sugars and other compounds by washing, citrus peel is largely composed of pectin, cellulose and hemicellulose. One of the major components, pectin can be modified using pectinesterases which reduces the degree of methylation (DM) to produce lower DM pectins which have great...

  15. Conductivity tensor of graphene dominated by spin-orbit coupling scatterers: A comparison between the results from Kubo and Boltzmann transport theories

    PubMed Central

    Liu, Zhe; Jiang, Liwei; Zheng, Yisong

    2016-01-01

    The diagonal and Hall conductivities of graphene arising from the spin-orbit coupling impurity scattering are theoretically studied. Based on the continuous model, i.e. the massless Dirac equation, we derive analytical expressions of the conductivity tensor from both the Kubo and Boltzmann transport theories. By performing numerical calculations, we find that the Kubo quantum transport result of the diagonal conductivity within the self-consistent Born approximation exhibits an insulating gap around the Dirac point. And in this gap a well-defined quantized spin Hall plateau occurs. This indicates the realization of the quantum spin Hall state of graphene driven by the spin-orbit coupling impurities. In contrast, the semi-classical Boltzmann theory fails to predict such a topological insulating phase. The Boltzmann diagonal conductivity is nonzero even in the insulating gap, in which the Boltzmann spin Hall conductivity does not exhibit any quantized plateau. PMID:27029398

  16. Conductivity tensor of graphene dominated by spin-orbit coupling scatterers: A comparison between the results from Kubo and Boltzmann transport theories.

    PubMed

    Liu, Zhe; Jiang, Liwei; Zheng, Yisong

    2016-03-31

    The diagonal and Hall conductivities of graphene arising from the spin-orbit coupling impurity scattering are theoretically studied. Based on the continuous model, i.e. the massless Dirac equation, we derive analytical expressions of the conductivity tensor from both the Kubo and Boltzmann transport theories. By performing numerical calculations, we find that the Kubo quantum transport result of the diagonal conductivity within the self-consistent Born approximation exhibits an insulating gap around the Dirac point. And in this gap a well-defined quantized spin Hall plateau occurs. This indicates the realization of the quantum spin Hall state of graphene driven by the spin-orbit coupling impurities. In contrast, the semi-classical Boltzmann theory fails to predict such a topological insulating phase. The Boltzmann diagonal conductivity is nonzero even in the insulating gap, in which the Boltzmann spin Hall conductivity does not exhibit any quantized plateau.

  17. A Method for Coupling a Direct Current Power Source Across a Dielectric Membrane or Other Non-Conducting Membrane

    DTIC Science & Technology

    2008-01-30

    on current (Ampere turns). One coil 300 is placed on the DC source side while a second coupled coil 310 is placed on the load side. The non-magnetic...outputs of the transformer 141 are electrically connected to two terminals 302, 304 of the first coupled coil 300 and two- terminal outputs 312, 314 of...the second coupled coil 310 are 24 Attomey Docket No. 84127 electrically connected to the terminal output of the second transformer 142. [0077] A non

  18. Morphing Surfaces Enable Acoustophoretic Contactless Transport of Ultrahigh-Density Matter in Air

    PubMed Central

    Foresti, Daniele; Sambatakakis, Giorgio; Bottan, Simone; Poulikakos, Dimos

    2013-01-01

    The controlled contactless transport of heavy drops and particles in air is of fundamental interest and has significant application potential. Acoustic forces do not rely on special material properties, but their utility in transporting heavy matter in air has been restricted by low power and poor controllability. Here we present a new concept of acoustophoresis, based on the morphing of a deformable reflector, which exploits the low reaction forces and low relaxation time of a liquid with enhanced surface tension through the use of thin overlaid membrane. An acoustically induced, mobile deformation (dimple) on the reflector surface enhances the acoustic field emitted by a line of discretized emitters and enables the countinuos motion of heavy levitated samples. With such interplay of emitters and reflecting soft-structure, a 5 mm steel sphere (0.5 grams) was contactlessly transported in air solely by acoustophoresis. PMID:24212104

  19. Calibration of Loop Antennas Using a Contactless Vector Network Analysis Method

    NASA Astrophysics Data System (ADS)

    Harm, M.; Kullmer, A.; Enders, A.

    2016-05-01

    The well-established calibration techniques for loop antennas have in common that either some parts of the antenna design or the field pattern of a standard field must be well known or fully theoretically describable. In this paper a pure metrological approach, circumventing these requirements is introduced and verified. It is based on a generic two port network model for loop antennas and a traceable contactless vector network analysis method.

  20. Contactless nondestructive measurement of bulk and surface recombination using frequency-modulated free carrier absorption

    NASA Astrophysics Data System (ADS)

    Sanii, F.; Giles, F. P.; Schwartz, R. J.; Gray, J. L.

    1992-03-01

    A measurement procedure is described which allows the contactless measurement of bulk lifetime and surface recombination. The procedure uses the the free-carrier absorption of a long-wavelength laser beam by a modulated free-carrier wave to measure and separate the bulk recombination from the surface recombination. The dependence of the absorption on the modulation frequency is used to accomplish the separation. Limitations of the technique are also discussed.

  1. Enhancing Optical Out-Coupling of Organic Light-Emitting Devices with Nanostructured Composite Electrodes Consisting of Indium Tin Oxide Nanomesh and Conducting Polymer.

    PubMed

    Chen, Chien-Yu; Lee, Wei-Kai; Chen, Yi-Jiun; Lu, Chun-Yang; Lin, Hoang Yan; Wu, Chung-Chih

    2015-09-02

    A nanostructured composite electrode consisting of a high-index indium-tin-oxide nanomesh and low-index high-conductivity conducting polymer effectively enhances coupling of internal radiation of organic light-emitting devices into their substrates. When combining this internal extraction structure and the external extraction scheme, a very high external quantum efficiency of nearly 62% is achieved with a green phosphorescent device.

  2. Creation of a dental X-ray unit with a contactless exposure control switch.

    PubMed

    Yoshida, M; Honda, E; Notsu, M; Maeda, N; Hosoki, H

    2014-01-01

    A new dental radiographic unit (DXRU) with a contactless switch for adjusting exposure conditions and a foot-pedal exposure switch was developed to prevent bacterial or viral contamination from patients and was compared with a conventional DXRU with a panel push-button switch with respect to user friendliness. 45 fourth-year dental school students carried out intraoral radiography using both types of DXRU. Errors regarding dose shortages of X-rays were compared and a questionnaire completed. 22 (49%) of the 45 students failed to provide the correct radiographic exposure and the number of errors was 32 for the conventional DXRU, and 4 (9%) students failed to provide the correct radiographic exposure and the number of errors was 4 for our new DXRU, at the first stage (p < 0.001). At the second stage, the number of students who failed to provide the correct radiographic exposure and the number of errors decreased to 12 and 16, respectively, for the conventional DXRU (p < 0.05). 37 (82%) of the 45 students preferred our DXRU because of its contactless switch and the push-pedal exposure switch. These data suggested that our new contactless mechanism should be used for other DXRUs for contamination control.

  3. Contactless Growth of ZnSe Single Crystals by Physical Vapor Transport

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; George, M. A.; Feth, S.; Lehoczky, S. L.

    1998-01-01

    ZnSe crystals were grown by self-seeded physical vapor transport (PVT) technique in the horizontal configuration. The source materials were heat treated by H2 reduction to remove the oxide followed by baking under dynamic vacuum to adjust the source composition toward that of congruent sublimation. Contactless growth of ZnSe single crystals have been performed consistently using three different source materials. The crystals grew away from the wall during the later stage of the growth with large (110) facets tend to align parallel to the gravity direction. The Scanning Electron Micrography (SEM) micrographs and the Atomic Force Microscope (AFM) images showed that large (110) terraces and steps dominate the as-grown facets. The measured residual gas pressures in the processed ampoules agree well among various source materials and the major components were CO and H2. No preferred growth direction was found. The one-dimensional diffusion model on the mass flux of a multi-species PVT system was employed to analyze the conditions for contactless growth. The calculated thermal profile for supersaturation is very close to the thermal profile measured inside the empty furnace bore in the region of contactless growth. The effects of convective flows in the vapor phase inside the ampoule on the growth processes are discussed.

  4. Terahertz time domain spectroscopy allows contactless monitoring of grapevine water status

    PubMed Central

    Santesteban, Luis G.; Palacios, Inés; Miranda, Carlos; Iriarte, Juan C.; Royo, José B.; Gonzalo, Ramón

    2015-01-01

    Agriculture is the sector with the greatest water consumption, since food production is frequently based on crop irrigation. Proper irrigation management requires reliable information on plant water status, but all the plant-based methods to determine it suffer from several inconveniences, mainly caused by the necessity of destructive sampling or of alteration of the plant organ due to contact installation. The aim of this work is to test if terahertz (THz) time domain reflectance measurements made on the grapevine trunk allows contactless monitoring of plant status. The experiments were performed on a potted 14-years-old plant, using a general purpose THz emitter receiver head. Trunk THz time-domain reflection signal proved to be very sensitive to changes in plant water availability, as its pattern follows the trend of soil water content and trunk growth variations. Therefore, it could be used to contactless monitor plant water status. Apart from that, THz reflection signal was observed to respond to light conditions which, according to a specifically designed girdling experiment, was caused by changes in the phloem. This latter results opens a promising field of research for contactless monitoring of phloem activity. PMID:26082791

  5. Electromagnetic characterization of the CFRPs anisotropic conductivity: modeling and measurements

    NASA Astrophysics Data System (ADS)

    Menana, H.; Féliachi, M.

    2011-02-01

    This work deals with the characterization of the conductivity tensor of a carbon fiber reinforced polymer composite (CFRP) thin plate. We propose a contactless method based on the eddy current non destructive testing technique. The used eddy current sensor consists of a ferrite torus on which a winding is wound. The torus is of a rectangular section and contains a thin air-gap in which the thin CFRP plate is inserted. We developed analytical relations giving the longitudinal and transversal conductivities of the CFRP plate as functions of the impedances variations of the eddy current sensor, corresponding to the orientations of the carbon fibers parallel and transverse to the direction of the torus width which is much greater than its thickness. The analytical relations are developed by inverting interpolation functions of curves giving the variations of the sensor impedances as functions of the longitudinal and transversal conductivities of the CFRP plate. These curves are obtained by a numerical model based on a simplified integro-differential formulation in terms of the electric vector potential in the CFRP plate, coupled to the magnetic circuit equations in the ferrite torus. The modeling results are supported by measurements.

  6. Mutual coupling between circular apertures on an infinite conducting ground plane and radiating into a finite width slab

    NASA Technical Reports Server (NTRS)

    Christodoulou, Christos

    1990-01-01

    The problem of electromagnetic coupling between two horns is of interest for the Microwave Reflectometer Ionization Sensor (MRIS) that will be used in the Aeroassist Flight Experiment (AFE). Laboratory measurements of mutual coupling between conical horns (using a flat metallic reflector to simulate a critically dense plasma outside) have shown a strong dependence on the finite dimensions of the shuttle tile over the apertures. Since both, the dielectric tile and the plasma outside the tile reflect microwaves, a study should be done to isolate the two mechanisms so that the MRIS reentry flight data can be interpreted correctly. Once the coupling due to the tile itself is determined then the location of the critial electron number density layers can be determined. As a first attempt to tackle this problem the Geometrical Theory of Diffraction was used to modify the existing solution to mutual coupling between apertures with infinite dielectric sheets. By using the equivalent current method, aperture theory to determine the radiated fields inside the dielectric tiles, and ray tracing the contributions to mutual coupling were determined. Results from two cases with different tile thicknesses have indicated that the main contribution to mutual coupling is due to diffraction from the bottom and top (back and front) wedges.

  7. Analysis of conductivity and dielectric spectra of Mn0.5Zn0.5Fe2O4 with coupled Cole-Cole type anomalous relaxations

    NASA Astrophysics Data System (ADS)

    Kumar, N. S. K.; Shahid, T. S.; Govindaraj, G.

    2016-05-01

    Most of the crystalline materials seldom show a well-defined dielectric loss peak due to domination of dc conductivity contribution, but effects of loss peaks are seen at high frequencies. Ac electrical data of nano-crystalline Mn0.5Zn0.5Fe2O4 synthesised by chemical co-precipitation method show such behaviour. Properly combined and formulated conduction and dielectric relaxation functions are required for such materials. Cole-Cole type relaxation function in the combined conduction and dielectric process is formulated for complex resistivity ρ*(ω), complex permittivity ε*(ω), complex conductivity σ*(ω) and complex electric modulus M*(ω). Conduction and dielectric relaxation are linked to Jonscher's idea of 'pinned dipole' and 'free dipole' to understand the relaxation dynamics. The physical parameters of 'pinned dipole' and 'free dipole' formalism are unique for all representations like ρ*(ω), ε*(ω), σ*(ω) and M*(ω). 'Pinned dipole' relaxation time τc related to conduction process and 'free dipole' relaxation time τd related to dielectric process show Arrhenius behaviour with the same activation energy. Correlation of dc conductivity σc with τc and τd indicates the coupled dynamics of 'pinned dipole' and 'free dipole'. Time-temperature scaling of conduction and dielectric relaxation reveals that the mechanism of coupled dynamics of 'pinned dipole' and 'free dipole' is temperature independent. Hopping of charge carriers with dynamics of disordered cation distribution of host matrix generates a coupled conduction and dielectric relaxation in Mn0.5Zn0.5Fe2O4.

  8. Strongly Coupled Plasma Research for the Equation of State and Conductivity of a Laser-Compressed Electron-Ion Plasma

    DTIC Science & Technology

    1981-08-15

    equation has to be solved by a numerical iterative procedure. We have shown that the Debye - Huckel gk cannot be used for the nurterical interation scheme...coupling theories and with other strong coupling schemes have been performed: theyconfirm the superiority of the present scheme.~ DD I AN7 1473J__SFI I...energy unit). An. alternatively useful characterization of the sys- tem is through the parameter y 3/2 (e ne 2 Zn/T)i the DEBYE wav4 number). The domain

  9. Contactless Microwave Characterization of Encapsulated Graphene p -n Junctions

    NASA Astrophysics Data System (ADS)

    Ranjan, V.; Zihlmann, S.; Makk, P.; Watanabe, K.; Taniguchi, T.; Schönenberger, C.

    2017-05-01

    Accessing intrinsic properties of a graphene device can be hindered by the influence of contact electrodes. Here, we capacitively couple graphene devices to superconducting resonant circuits and observe clear changes in the resonance frequency and widths originating from the internal charge dynamics of graphene. This allows us to extract the density of states and charge relaxation resistance in graphene p -n junctions without the need for electrical contacts. The presented characterization paves a fast, sensitive, and noninvasive measurement of graphene nanocircuits.

  10. Contactless ultrasound detection using an optical ring resonator

    NASA Astrophysics Data System (ADS)

    Kim, Kyu Hyun; Luo, Wei; Zhang, Cheng; Guo, L. Jay; Fan, Xudong

    2016-03-01

    We develop an air-couple ultrasound detector based on an optical fluidic ring resonator (OFRR) suspended on a Ushaped holder. The OFRR is a glass capillary with an outer diameter of approximately 130 μm and a wall thickness in the order of 1~10 μm. The circular cross section of the OFRR supports the high-Q whispering gallery mode (WGM) that circulates along the circumference. Incoming ultrasound pressure results in a small refractive index change in the glass wall and geometrical change in the OFRR shape, both of which in turn lead to a spectral shift in the WGM that can be sensitively detected owing to WGM with high optical Q-factors (>107). Due to the suspension nature of the OFRR, the ultrasound detection can be carried out in air, which is advantageous in comparison with other ultrasound detections that require acoustic coupling media such water, gel or solid. The sensitivity can be tuned and optimized by changing the diameter and wall thickness. Besides the optical detection, we also demonstrate optomechanical ultrasound mixing, in which optomechanical vibration is first excited within the OFRR that subsequently modulates the ultrasound wave. Our work will lead to the development of a new type of air-coupled ultrasound detector that can be used for photo-acoustic imaging, non-invasive ultrasound detection of external objects, and ultrasound detection/characterization of internal objects (such as particles and liquids) flowing inside the capillary.

  11. Electronic band structure of compressively strained Ge{sub 1−x}Sn{sub x} with x < 0.11 studied by contactless electroreflectance

    SciTech Connect

    Zelazna, K.; Polak, M. P.; Scharoch, P.; Gladysiewicz, M.; Misiewicz, J.; Kudrawiec, R.; Serafinczuk, J.

    2015-04-06

    Contactless electroreflectance is applied to study direct optical transitions from the heavy hole, light hole, and spin-orbit split-off band to the conduction band in compressively strained Ge{sub 1−x}Sn{sub x} layers of various Sn concentrations at room temperature. It is shown that the energies of these transitions are in very good agreement with theoretical predictions, which take into account non-linear variation of bandgap and spin-orbit splitting plus the strain-related shifts obtained from the Bir-Pikus theory. The bowing parameter for the direct bandgap has been determined to be 1.8 ± 0.2 eV and agree with this one obtained within ab initio calculations, which is 1.97 eV (for indirect bandgap the bowing parameter is 0.26 eV)

  12. Higher-order results for the relation between channel conductance and the Coulomb blockade for two tunnel-coupled quantum dots

    NASA Astrophysics Data System (ADS)

    Golden, John M.; Halperin, Bertrand I.

    1996-12-01

    We extend earlier results on the relation between the dimensionless tunneling channel conductance g and the fractional Coulomb-blockade peak splitting f for two electrostatically equivalent dots connected by an arbitrary number Nch of tunneling channels with bandwidths W much larger than the two-dot differential charging energy U2. By calculating f through the second order in g in the limit of weak coupling (g-->0), we illuminate the difference in behavior of the large-Nch and small-Nch regimes and make more plausible extrapolation to the strong-coupling (g-->1) limit. For the special case of Nch=2 and strong coupling, we eliminate an apparent ultraviolet divergence and obtain the next leading term of an expansion in (1-g). We show that the results we calculate are independent of such band structure details as the fraction of occupied fermionic single-particle states in the weak-coupling theory and the nature of the cutoff in the bosonized strong-coupling theory. The results agree with calculations for metallic junctions in the Nch-->∞ limit and improve the previous good agreement with recent two-channel experiments.

  13. The application of fractional order control for an air-based contactless actuation system.

    PubMed

    Krijnen, Martijn E; van Ostayen, Ron A J; HosseinNia, Hassan

    2017-04-25

    Industry pushes towards ever faster and more accurate production of thin substrates. Contactless positioning offers advantages, especially in terms of risk of breakage and contamination. A system is considered designed for contactless positioning by floating a silicon wafer on a thin film of air. This paper focuses on the design of a control system, including actuators, sensors and control method, suitable for this purpose. Two cascaded control loops, with decoupled SISO controllers, are implemented for this moving mass controlled on a mass-spring system, which can be modelled as a fourth order system. The SISO controllers are first designed with classic loopshaping tools, which are then modified using fractional control. Two arguments based on examples in this system are given for the application of fractional control. Firstly, to increase the bandwidth of a regular mass-spring system, and secondly to control a plant which behaves fundamentally fractional, such as the moving mass in this cascaded fourth order system. By merely the application of fractionality, the bandwidths are extended by 14.6 % and 62 %, for the inner and outer loop respectively. A closed-loop positioning bandwidth of the wafer of 60Hz is achieved, resulting in a positioning error of 104nm (2σ value), which is limited by sensor noise and pressure disturbances. This paper shows how the extension of classic loopshaping tools with fractional control can directly improve the performance, without adding to the complicatedness of the control system. Moreover it demonstrates a working concept of a novel type of contactless actuator. Copyright © 2017. Published by Elsevier Ltd.

  14. All You Can Eat or Breaking a Real-World Contactless Payment System

    NASA Astrophysics Data System (ADS)

    Kasper, Timo; Silbermann, Michael; Paar, Christof

    We investigated a real-world contactless payment application based on mifare Classic cards. In order to analyze the security of the payment system, we combined previous cryptanalytical results and implemented an improved card-only attack with customized low-cost tools, that is to our knowledge the most efficient practical attack to date. We found several flaws implying severe security vulnerabilities on the system level that allow for devastating attacks including identity theft and recharging the amount of money on the cards. We practically verify and demonstrate the attacks on the commercial system.

  15. Software Defined Doppler Radar as a Contactless Multipurpose Microwave Sensor for Vibrations Monitoring

    PubMed Central

    Raffo, Antonio; Costanzo, Sandra; Di Massa, Giuseppe

    2017-01-01

    A vibration sensor based on the use of a Software-Defined Radio (SDR) platform is adopted in this work to provide a contactless and multipurpose solution for low-cost real-time vibrations monitoring. In order to test the vibration detection ability of the proposed non-contact method, a 1 GHz Doppler radar sensor is simulated and successfully assessed on targets at various distances, with various oscillation frequencies and amplitudes. Furthermore, an SDR Doppler platform is practically realized, and preliminary experimental validations on a device able to produce a harmonic motion are illustrated to prove the effectiveness of the proposed approach. PMID:28075345

  16. Software Defined Doppler Radar as a Contactless Multipurpose Microwave Sensor for Vibrations Monitoring.

    PubMed

    Raffo, Antonio; Costanzo, Sandra; Di Massa, Giuseppe

    2017-01-08

    A vibration sensor based on the use of a Software-Defined Radio (SDR) platform is adopted in this work to provide a contactless and multipurpose solution for low-cost real-time vibrations monitoring. In order to test the vibration detection ability of the proposed non-contact method, a 1 GHz Doppler radar sensor is simulated and successfully assessed on targets at various distances, with various oscillation frequencies and amplitudes. Furthermore, an SDR Doppler platform is practically realized, and preliminary experimental validations on a device able to produce a harmonic motion are illustrated to prove the effectiveness of the proposed approach.

  17. Combined simulation of a micro permanent magnetic linear contactless displacement sensor.

    PubMed

    Gao, Jing; Müller, Wolfgang F O; Greiner, Felix; Eicher, Dirk; Weiland, Thomas; Schlaak, Helmut F

    2010-01-01

    The permanent magnetic linear contactless displacement (PLCD) sensor is a new type of displacement sensor operating on the magnetic inductive principle. It has many excellent properties and has already been used for many applications. In this article a Micro-PLCD sensor which can be used for microelectromechanical system (MEMS) measurements is designed and simulated with the CST EM STUDIO(®) software, including building a virtual model, magnetostatic calculations, low frequency calculations, steady current calculations and thermal calculations. The influence of some important parameters such as air gap dimension, working frequency, coil current and eddy currents etc. is studied in depth.

  18. Feedback and control in integrated optics enabled by contactLess integrated photonic probe

    NASA Astrophysics Data System (ADS)

    Annoni, Andrea; Morichetti, Francesco; Grillanda, Stefano; Peserico, Nicola; Carminati, Marco; Ciccarella, Pietro; Ferrari, Giorgio; Sampietro, Marco; Melloni, Andrea

    2015-02-01

    We demonstrate non-invasive light observation in silicon photonics with a ContactLess Integrated Photonics Probe (CLIPP), neither introducing appreciable perturbations of the optical field nor requiring photon tapping from the waveguide. Light monitoring with sensitivity down to -30 dBm, across 40 dB dynamic range, in few tens of microseconds, on TE and TM polarizations, and on monomode and multimode waveguides is achieved. Moreover, we show wavelength tuning, locking and swapping of high-Q resonators assisted by the CLIPP that is integrated inside the microring. CLIPP readout and feedback control is managed by a CMOS microelectronic circuit bridged to the silicon photonic chip.

  19. Contactless steering of a plasma jet with a 3D magnetic nozzle

    NASA Astrophysics Data System (ADS)

    Merino, Mario; Ahedo, Eduardo

    2017-09-01

    A 3D, steerable magnetic nozzle (MN) is presented that enables contactless thrust vector control of a plasma jet without any moving parts. The concept represents a substantial simplification over current plasma thruster gimbaled platforms, and requires only a small modification in thrusters that already have a MN. The characteristics of the plasma expansion in the 3D magnetic field and the deflection performance of the device are characterized with a fully magnetized plasma model, suggesting that thrust deflections of 5° -10° are readily achievable.

  20. Active angular alignment of gauge block in system for contactless gauge block calibration

    NASA Astrophysics Data System (ADS)

    Buchta, Zdeněk.; Šarbort, Martin; Řeřucha, Šimon; Hucl, Václav; Čížek, Martin; Lazar, Josef; Číp, Ondřej

    2014-05-01

    This paper presents a method for active angular alignment of gauge block implemented in a system for automatic contactless calibration of gauge blocks designed at ISI ASCR. The system combines low-coherence interferometry and laser interferometry, where the first identifies the gauge block sides position and the second one measures the gauge block length itself. A crucial part of the system is the algorithm for gauge block alignment to the measuring beam which is able to compensate the gauge block lateral and longitudinal tilt up to 0.141 mrad. The algorithm is also important for the gauge block position monitoring during its length measurement.

  1. A novel ultra-wideband 80 GHz FMCW radar system for contactless monitoring of vital signs.

    PubMed

    Wang, Siying; Pohl, Antje; Jaeschke, Timo; Czaplik, Michael; Köny, Marcus; Leonhardt, Steffen; Pohl, Nils

    2015-01-01

    In this paper an ultra-wideband 80 GHz FMCW-radar system for contactless monitoring of respiration and heart rate is investigated and compared to a standard monitoring system with ECG and CO(2) measurements as reference. The novel FMCW-radar enables the detection of the physiological displacement of the skin surface with submillimeter accuracy. This high accuracy is achieved with a large bandwidth of 10 GHz and the combination of intermediate frequency and phase evaluation. This concept is validated with a radar system simulation and experimental measurements are performed with different radar sensor positions and orientations.

  2. Synergetic effect of spin-orbit coupling and Zeeman splitting on the optical conductivity in the one-dimensional Hubbard model

    NASA Astrophysics Data System (ADS)

    Bolens, Adrien; Katsura, Hosho; Ogata, Masao; Miyashita, Seiji

    2017-06-01

    We study how the synergetic effect of spin-orbit coupling (SOC) and Zeeman splitting (ZS) affects the optical conductivity in the one-dimensional Hubbard model using the Kubo formula. We focus on two phenomena: (1) the electric dipole spin resonance (EDSR) in the metallic regime and (2) the optical conductivity in the Mott-insulating phase above the optical gap. In both cases, we calculate qualitatively the effects of SOC and ZS and how they depend on the relative angle between the SOC vector and the magnetic field direction. First, we investigate the spin resonance without electron correlation (the Hubbard parameter U =0 ). Although, neither SOC nor ZS causes any resonance by itself in the optical conductivity, the EDSR becomes possible when both of them exist. The resulting contribution to the optical conductivity is analyzed analytically. The effect of U on the spin resonance is also studied with a numerical method. It is found that at half filling, the resonance is first enhanced for small U and then suppressed when the optical gap is large enough. In the strong coupling limit U →∞ at half filling, we also refer to the resonance between the lower and upper Hubbard bands appearing at ω ˜U , above the optical gap. A large magnetic field tends to suppress the signal while it is recovered thanks to SOC depending on the relative angle of the magnetic field.

  3. Long-range coupling between the extracellular gates and the intracellular ATP binding domains of multidrug resistance protein pumps and cystic fibrosis transmembrane conductance regulator channels

    PubMed Central

    Wei, Shipeng; Roessler, Bryan C.; Icyuz, Mert; Chauvet, Sylvain; Tao, Binli; Hartman, John L.; Kirk, Kevin L.

    2015-01-01

    The ABCC transporter subfamily includes pumps, the long and short multidrug resistance proteins (MRPs), and an ATP-gated anion channel, the cystic fibrosis transmembrane conductance regulator (CFTR). We show that despite their thermodynamic differences, these ABCC transporter subtypes use broadly similar mechanisms to couple their extracellular gates to the ATP occupancies of their cytosolic nucleotide binding domains. A conserved extracellular phenylalanine at this gate was a prime location for producing gain of function (GOF) mutants of a long MRP in yeast (Ycf1p cadmium transporter), a short yeast MRP (Yor1p oligomycin exporter), and human CFTR channels. Extracellular gate mutations rescued ATP binding mutants of the yeast MRPs and CFTR by increasing ATP sensitivity. Control ATPase-defective MRP mutants could not be rescued by this mechanism. A CFTR double mutant with an extracellular gate mutation plus a cytosolic GOF mutation was highly active (single-channel open probability >0.3) in the absence of ATP and protein kinase A, each normally required for CFTR activity. We conclude that all 3 ABCC transporter subtypes use similar mechanisms to couple their extracellular gates to ATP occupancy, and highly active CFTR channels that bypass defects in ATP binding or phosphorylation can be produced.—Wei, S., Roessler, B. C., Icyuz, M., Chauvet, S., Tao, B., Hartman IV, J. L., Kirk, K. L. Long-range coupling between the extracellular gates and the intracellular ATP binding domains of multidrug resistance protein pumps and cystic fibrosis transmembrane conductance regulator channels. PMID:26606940

  4. Conductivity measures coupled with treatment with ion-exchange resin for the assessment of sodium concentration in physiological fluids: analyses on artificial solutions

    NASA Astrophysics Data System (ADS)

    Tura, A.; Sbrignadello, S.; Mambelli, E.; Ravazzani, P.; Santoro, A.; Pacini, G.

    2013-09-01

    In humans, sodium is essential for the regulation of blood volume and pressure. During hemodialysis, sodium measurement is important to preserve the patient from hypo- or hyper-natremia Usually, sodium measurement is performed through laboratory equipment which is typically expensive, and requires manual intervention. We propose a new method, based on conductivity measurement after treatment of dialysate solution through ion-exchange resin. To test this method, we performed in vitro experiments. We prepared 40 ml sodium chloride (NaCl) samples at 280, 140, 70, 35, 17.5, 8.75, 4.375 mEq/l, and some "mixed samples", i.e., with added potassium chloride (KCl) at different concentrations (4.375-17.5 mEq/l), to simulate the confounding factors in a conductivity-based sodium measurement. We measured the conductivity of all samples. Afterwards, each sample was treated for 1 min with 1 g of Dowex G-26 resin, and conductivity measured again. On average, the difference ɛ in the conductivity between mixed samples and corresponding pure NaCl samples (at the same NaCl concentration) was 20.9%. With treatment with the resin, it was 9.9%, only. We conclude that ion-exchange resin treatment coupled with conductivity measures may be a possible simple approach for continuous and automatic sodium measurement during hemodialysis.

  5. Measurements of the Conduction-Zone Length and Mass Ablation Rate to Study the Hydrodynamic Coupling in Cryogenic Direct-Drive Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Michel, D. T.; Davis, A. K.; Goncharov, V. N.; Regan, S. P.; Sangster, T. C.; Epstein, R.; Hu, S. X.; Igumenshchev, I. V.; Meyerhofer, D. D.; Seka, W.; Froula, D. H.

    2015-11-01

    The ablation-front trajectory and the averaged mass ablation rate is measured in direct-drive cryogenic target implosions on the OMEGA Laser System by imaging the soft x rays emitted by the coronal plasma. The length of the conduction zone is determined by coupling x-ray and scattered-light measurements. These measurements are compared to hydrodynamic simulations to study the modeling of the hydrodynamic coupling for various beam and target radii. Reducing the beam focal-spot radius relative to the target radius is a method that is being studied to reduce cross-beam energy transfer and increase the hydrodynamic efficiency. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  6. Effects of coulomb repulsion on conductivity of heterojunction carbon nanotube quantum dots with spin-orbital coupling and interacting leads

    NASA Astrophysics Data System (ADS)

    Ogloblya, O. V.; Kuznietsova, H. M.; Strzhemechny, Y. M.

    2017-01-01

    We performed numerical studies for the conductance of a heterojunction carbon nanotube quantum dot (QD) with an extra spin orbital quantum number and a conventional QD in which the electron state is determined only by the spin quantum number. Our computational approach took into account the spin-orbit interaction and the Coulomb repulsion both between electrons on a QD as well as between the QD electron and the contacts. We utilized an approach based on the Keldysh non-equilibrium Green's function formalism as well as the equation of motion technique. We focused on the case of a finite Coulombic on-site repulsion and considered two possible cases of applied voltage: spin bias and conventional bias. For the system of interest we obtained bias spectroscopy diagrams, i.e. contour charts showing dependence of conductivity on two variables - voltage and the energy level position in a QD - which can be controlled by the plunger gate voltage. The finite Coulombic repulsion splits the density of states into two distinct maxima with the energy separation between them controlled by that parameter. It was also shown that an increase of either the value of the on-site Coulomb repulsion in a QD or the parameter of the Coulomb repulsion between the electrons in the QD and the contacts leads to an overall shift of the density of electronic states dependence toward higher energy values. Presence of the QD-lead interaction yields formation of a new pair of peaks in the differential conductance dependence. We also show that existence of four quantum states in a QD leads to abrupt changes in the density of states. These results could be beneficial for potential applications in nanotube-based amperometric sensors.

  7. Allosteric interactions and proton conducting pathways in proton pumping aa(3) oxidases: heme a as a key coupling element.

    PubMed

    Capitanio, Nazzareno; Palese, Luigi Leonardo; Capitanio, Giuseppe; Martino, Pietro Luca; Richter, Oliver-Matthias H; Ludwig, Bernd; Papa, Sergio

    2012-04-01

    In this paper allosteric interactions in protonmotive heme aa(3) terminal oxidases of the respiratory chain are dealt with. The different lines of evidence supporting the key role of H(+)/e(-) coupling (redox Bohr effect) at the low spin heme a in the proton pump of the bovine oxidase are summarized. Results are presented showing that the I-R54M mutation in P. denitrificans aa(3) oxidase, which decreases by more than 200mV the E(m) of heme a, inhibits proton pumping. Mutational amino acid replacement in proton channels, at the negative (N) side of membrane-inserted prokaryotic aa(3) oxidases, as well as Zn(2+) binding at this site in the bovine oxidase, uncouples proton pumping. This effect appears to result from alteration of the structural/functional device, closer to the positive, opposite (P) surface, which separates pumped protons from those consumed in the reduction of O(2) to 2 H(2)O. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Mechanically exfoliated MoS2 sheet coupled with conductive polyaniline as a superior supercapacitor electrode material.

    PubMed

    Ansari, Sajid Ali; Fouad, H; Ansari, S G; Sk, Md Palashuddin; Cho, Moo Hwan

    2017-10-15

    The development of electrically conductive metal sulfide-based polymer nanocomposites for energy storage materials has been a major focus by researchers to solve the energy crisis. In this study, a simple and facile method was used to construct a nanocomposite by combining a mechanically exfoliated MoS2 (M-MoS2) sheet with polyaniline (Pani) using a simple and scalable in-situ chemical oxidative polymerization method. The as-prepared nanocomposite (M-MoS2-Pani nanocomposite) was characterized further by usual basic spectroscopic techniques, such as X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The electrochemical supercapacitive characteristics of the M-MoS2-Pani nanocomposite was tested in a three-electrode assembly by obtaining cyclic voltammetric (CV) curves and galvanostatic charge-discharge (GCD) measurements. The results were compared with those of a C-MoS2-Pani nanocomposite that had been synthesized using bulk MoS2. The M-MoS2-Pani nanocomposite synthesized using exfoliated MoS2 exhibited a higher specific capacitance of 510.12Fg(-1) at a current of 1Ag(-1) than the C-MoS2-Pani nanocomposite (225.15Fg(-1)), which was synthesized using bulk C-MoS2 delivered. The enhanced electrochemical supercapacitive performance was correlated to the synergistic effect and chemical interactions between the Pani and MoS2, which provide high electrical conductivity and a sufficient empty state for electrode/electrolyte contact. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Feasibility study of a swept frequency electromagnetic probe (SWEEP) using inductive coupling for the determination of subsurface conductivity of the earth and water prospecting in arid regions

    NASA Technical Reports Server (NTRS)

    Latorraca, G. A.; Bannister, L. H.

    1974-01-01

    Techniques developed for electromagnetic probing of the lunar interior, and techniques developed for the generation of high power audio frequencies were combined to make practical a magnetic inductive coupling system for the rapid measurement of ground conductivity profiles which are helpful when prospecting for the presence and quality of subsurface water. A system which involves the measurement of the direction, intensity, and time phase of the magnetic field observed near the surface of the earth at a distance from a horizontal coil energized so as to create a field that penetrates the earth was designed and studied to deduce the conductivity and stratification of the subsurface. Theoretical studies and a rudimentary experiment in an arid region showed that the approach is conceptually valid and that this geophysical prospecting technique can be developed for the economical exploration of subterranean water resources.

  10. Solar cycle dependence of nightside field-aligned currents: Effects of dayside ionospheric conductivity on the solar wind-magnetosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Ohtani, S.; Wing, S.; Merkin, V. G.; Higuchi, T.

    2014-01-01

    the present study we observationally address the role of ionospheric conductivity in the solar wind-magnetosphere coupling in terms of global field-aligned currents (FACs). Solar EUV irradiance changes during a solar cycle and so does its contribution to the ionospheric conductivity. We statistically examine how, under fixed external conditions, the intensities of the R1 and R2 currents and their demarcation latitude depend on solar activity (F10.7). An emphasis is placed on nightside FACs in the dark hemisphere. The result shows that for fixed ranges of interplanetary electric field, the nightside FACs are more intense for higher solar activity irrespective of their polarities or local times. It is also found that the R1-R2 pair, therefore the auroral oval, moves equatorward as the solar activity increases. For both current intensity and latitude, the dependence on F10.7 is more sensitive at smaller F10.7 and it levels off with increasing F10.7. The intensities of dayside FACs reveal similar F10.7 dependence as expected from the enhancement of the local ionospheric conductance. Interestingly, they also move equatorward with increasing F10.7. It is expected from force balance that as the dayside R1 current becomes more intense with increasing solar activity, the magnetosphere shrinks on the day side and expands on the night side. This configurational change of the magnetosphere presumably affects the energy transport from the solar wind to the magnetosphere, although its details still remain to be understood. We conclude that the ionospheric conductivity plays an active role in the solar wind-magnetosphere-ionosphere coupling.

  11. Effects of Dayside Ionospheric Conductivity on the Solar Wind-Magnetosphere-Ionosphere Coupling: Solar Cycle Dependence of Night-side Field-aligned Currents

    NASA Astrophysics Data System (ADS)

    Ohtani, S.; Higuchi, T.; Wing, S.; Merkin, V. G.

    2014-12-01

    In the present study we observationally address the role of ionospheric conductivity in the solar wind-magnetosphere coupling in terms of global field-aligned currents (FACs). Solar EUV irradiance changes during a solar cycle, and so does its contribution to the ionospheric conductivity. We statistically examine how, under fixed external conditions, the intensities of the R1 and R2 currents and their demarcation latitude depend on solar activity (F10.7). An emphasis is placed on nightside FACs in the dark hemisphere. The result shows that for fixed ranges of interplanetary electric field, the nightside FACs are more intense for higher solar activity irrespective of their polarities or local times. It is also found that the R1-R2 pair, therefore the auroral oval, moves equatorward as the solar activity increases. For both current intensity and latitude, the dependence on F10.7 is more sensitive at smaller F10.7 and it levels off with increasing F10.7. The intensities of dayside FACs reveal similar F10.7 dependence as expected from the enhancement of the local ionospheric conductance. Interestingly, they also move equatorward with increasing solar activity. It is expected from force balance that as the dayside R1 current becomes more intense with increasing solar activity, the magnetosphere shrinks on the day side and expands on the night side. This configurational change of the magnetosphere presumably affects the energy transport from the solar wind to the magnetosphere, although its details still remain to be understood. We conclude that the ionospheric conductivity actively affects the solar wind-magnetosphere-ionosphere coupling.

  12. Introducing Contactless Blood Pressure Assessment Using a High Speed Video Camera.

    PubMed

    Jeong, In Cheol; Finkelstein, Joseph

    2016-04-01

    Recent studies demonstrated that blood pressure (BP) can be estimated using pulse transit time (PTT). For PTT calculation, photoplethysmogram (PPG) is usually used to detect a time lag in pulse wave propagation which is correlated with BP. Until now, PTT and PPG were registered using a set of body-worn sensors. In this study a new methodology is introduced allowing contactless registration of PTT and PPG using high speed camera resulting in corresponding image-based PTT (iPTT) and image-based PPG (iPPG) generation. The iPTT value can be potentially utilized for blood pressure estimation however extent of correlation between iPTT and BP is unknown. The goal of this preliminary feasibility study was to introduce the methodology for contactless generation of iPPG and iPTT and to make initial estimation of the extent of correlation between iPTT and BP "in vivo." A short cycling exercise was used to generate BP changes in healthy adult volunteers in three consecutive visits. BP was measured by a verified BP monitor simultaneously with iPTT registration at three exercise points: rest, exercise peak, and recovery. iPPG was simultaneously registered at two body locations during the exercise using high speed camera at 420 frames per second. iPTT was calculated as a time lag between pulse waves obtained as two iPPG's registered from simultaneous recoding of head and palm areas. The average inter-person correlation between PTT and iPTT was 0.85 ± 0.08. The range of inter-person correlations between PTT and iPTT was from 0.70 to 0.95 (p < 0.05). The average inter-person coefficient of correlation between SBP and iPTT was -0.80 ± 0.12. The range of correlations between systolic BP and iPTT was from 0.632 to 0.960 with p < 0.05 for most of the participants. Preliminary data indicated that a high speed camera can be potentially utilized for unobtrusive contactless monitoring of abrupt blood pressure changes in a variety of settings. The initial prototype system was able to

  13. Global MHD simulations of Mercury's magnetosphere with coupled planetary interior: Induction effect of the planetary conducting core on the global interaction

    NASA Astrophysics Data System (ADS)

    Jia, Xianzhe; Slavin, James A.; Gombosi, Tamas I.; Daldorff, Lars K. S.; Toth, Gabor; Holst, Bart

    2015-06-01

    Mercury's comparatively weak intrinsic magnetic field and its close proximity to the Sun lead to a magnetosphere that undergoes more direct space-weathering interactions than other planets. A unique aspect of Mercury's interaction system arises from the large ratio of the scale of the planet to the scale of the magnetosphere and the presence of a large-size core composed of highly conducting material. Consequently, there is strong feedback between the planetary interior and the magnetosphere, especially under conditions of strong external forcing. Understanding the coupled solar wind-magnetosphere-interior interaction at Mercury requires not only analysis of observations but also a modeling framework that is both comprehensive and inclusive. We have developed a new global MHD model for Mercury in which the planetary interior is modeled as layers of different electrical conductivities that electromagnetically couple to the surrounding plasma environment. This new modeling capability allows us to characterize the dynamical response of Mercury to time-varying external conditions in a self-consistent manner. Comparison of our model results with observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft shows that the model provides a reasonably good representation of the global magnetosphere. To demonstrate the capability to model induction effects, we have performed idealized simulations in which Mercury's magnetosphere is impacted by a solar wind pressure enhancement. Our results show that due to the induction effect, Mercury's core exerts strong global influences on the way Mercury responds to changes in the external environment, including modifying the global magnetospheric structure and affecting the extent to which the solar wind directly impacts the surface. The global MHD model presented here represents a crucial step toward establishing a modeling framework that enables self-consistent characterization of Mercury

  14. Plasticizing effect of K+ ions and succinonitrile on electrical conductivity of [poly(ethylene oxide)-succinonitrile]/KI-I2 redox-couple solid polymer electrolyte.

    PubMed

    Gupta, Ravindra Kumar; Rhee, Hee-Woo

    2013-06-20

    The plasticizing effect of the K(+) ions and succinonitrile on the electrical conductivity of a new redox-couple solid polymer electrolyte system, (1 - x)[0.5poly(ethylene oxide):0.5succinonitrile]:x[0.9KI:0.1I2] with x = 0-0.2 in weight fraction, is reported. An increase of x resulted in an increase of the electrical conductivity (σ25°C) of the electrolyte. The electrolyte with x = 0.15 exhibited the highest σ25°C value, ~7 × 10(-4) S cm(-1), and is referred to as the optimum conducting composition (OCC). In addition to an increase of the mobile ion concentration with increasing x, X-ray diffractometry, Fourier-transform infrared spectroscopy, polarized optical microscopy, UV-vis spectroscopy, and differential scanning calorimetry studies revealed a decrease of poly(ethylene oxide) crystallinity/an increase of ionic mobility, indicating the plasticizing effect of the K(+) ions. Plasticizing and molecular diffusing properties of the succinonitrile further helped to improve the electrical conductivity of the electrolyte.

  15. A coupled monitoring network to conduct an assessment of mercury transformation and mobilization in floodplain soils: South River, Virginia

    NASA Astrophysics Data System (ADS)

    Lazareva, O.; Sparks, D. L.; Landis, R.; Ptacek, C. J.; Hicks, S.; Montgomery, D.

    2013-12-01

    Mercury (Hg) was used between 1929 and 1950 by the DuPont plant in the production of rayon acetate fiber in Waynesboro, Virginia and released into the South River. The contamination of Hg was discovered in the 1970s and remained elevated in water, soil, sediments, and biota. The primary goal of this study is to investigate the processes that govern biogeochemical transformation and mobilization of Hg in floodplain soils at South River Mile 3.5, characterize geochemical gradients in soils and how they change over time, and to enable targeted sampling at Hg loading hot spots. The biogeochemical data will play a supporting role and be used to further develop our understanding of the processes controlling the leaching of Hg and our conceptual model. Our over-arching hypothesis is to test if leaching of bank soils is a significant source of dissolved or colloidal inorganic Hg. This effort requires an interdisciplinary geochemical approach and sensor technology to understand the interactions between floodplain soil, groundwater, and river. Our investigation will include 10 months' worth data from a number of state-of-the-art in-situ monitoring sensors, such as custom-designed redox probes, soil moisture, temperature, pressure, and conductivity installed at the site. Our preliminary results showed that the concentration of total Hg in soils was up to 900 mg/kg (wet weight).There is a significant redox gradient across the floodplain soil profile. Within the top 40 -70 cm, major changes in redox conditions from oxidizing (Eh ≈+600 mV) to very reducing (Eh ≈-300 mV) corresponded to heavy rainfall and overbank flooding events. High variations in stream stage may govern the surface water - groundwater exchange facilitating the downward or upward movement of the capillary fringe and saturated zone through the soil horizons, affecting soil redox potential, stability of Hg-bearing minerals and leaching of inorganic Hg into dissolved and colloidal phases. These phases may be

  16. Can carbon nanotube fibers achieve the ultimate conductivity?—Coupled-mode analysis for electron transport through the carbon nanotube contact

    NASA Astrophysics Data System (ADS)

    Xu, Fangbo; Sadrzadeh, Arta; Xu, Zhiping; Yakobson, Boris I.

    2013-08-01

    Recent measurements of carbon nanotube (CNT) fibers electrical conductivity still show the values lower than that of individual CNTs, by about one magnitude order. The imperfections of manufacturing process and constituent components are described as culprits. What if every segment is made perfect? In this work, we study the quantum conductance through the parallel junction of flawless armchair CNTs using tight-binding method in conjunction with non-equilibrium Green's function approach. Short-range oscillations within the long-range oscillations as well as decaying envelopes are all observed in the computed Fermi-level (low bias) conductance as a function of contact length, L. The propagation of CNTs' Bloch waves is cast in the coupled-mode formalism and helps to reveal the quantum interference nature of various behaviors of conductance. Our analysis shows that the Bloch waves at the Fermi-level propagate through a parallel junction without reflection only at an optimal value of contact length. For quite a long junction, however, the conductance at the Fermi level diminishes due to the perturbation of periodic potential field of close-packed CNTs. Thus, a macroscopic fiber, containing an infinite number of junctions, forms a filter that permits passage of electrons with specific wave vectors, and these wave vectors are determined by the collection of all the junction lengths. We also argue that the energy gap introduced by long junctions can be overcome by small voltage (˜0.04 V) across the whole fiber. Overall, developing long individual all-armchair metallic CNTs serves as a promising way to the manufacture of high-conductivity fibers.

  17. Hybrid Li Ion Conducting Membrane as Protection for the Li Anode in an Aqueous Li-Air Battery: Coupling Sol-Gel Chemistry and Electrospinning.

    PubMed

    Lancel, Gilles; Stevens, Philippe; Toussaint, Gwenaëlle; Maréchal, Manuel; Krins, Natacha; Bregiroux, Damien; Laberty-Robert, Christel

    2017-09-19

    Aqueous lithium-air batteries have very high theoretical energy densities, which potentially makes this technology very interesting for energy storage in electric mobility applications. However, the aqueous electrolyte requires the use of a watertight layer to protect the lithium metal, typically a thick NASICON glass-ceramic layer, which adds ohmic resistance and penalizes performance. This article deals with the replacement of this ceramic electrolyte by a hybrid organic-inorganic membrane. This new membrane combines an ionically conducting inorganic phase for Li ion transport (Li1.3Al0.3Ti1.7(PO4)3 (LATP) and a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer for water tightness and mechanical properties. The Li ion transport through the membrane is ensured by an interconnected 3-D network of crystalline LATP fibers obtained by coupling an electrospinning process with the sol-gel synthesis followed by thermal treatment. After an impregnation step with PVDF-HFP, hybrid membranes with different volumetric fractions of PVDF-HFP were synthesized. These membranes are watertight and have Li ion conductivities ranging from 10(-5) to 10(-4) mS/cm. The conductivity depends on the PVDF-HFP volume fraction and the fibers' alignment in the membrane thickness, which in turn can be tuned by adjusting the water content in the electrospinning chamber during the process. The alignment of fibers parallel to the membrane surface is conductive to poor conductivity values whereas a disordered fiber mat leads to interesting conductivity values (1 × 10(-4) mS/cm) at ambient temperature.

  18. Contactless temperature determination using dual-channel lock-in phosphor thermometry

    NASA Astrophysics Data System (ADS)

    Hashemi, Amir; Jovicic, Gordana; Batentschuk, Miroslaw; Brabec, Christoph J.; Vetter, Andreas

    2017-02-01

    In this paper, we present dual-channel lock-in phosphor thermometry, which offers an option of accurate and contactless temperature determination under high environmental noise. We studied YAG:Dy as thermographic phosphor at an excitation wavelength of 405 nm. We tested our approach under different experimental conditions with noise levels of about 550, 1060 and 2190 times larger than the excitation signal. With the dual-channel lock-in setup, we were able to suppress the strong noise in all cases and to reliably determine surface temperature using our optical measurements (error  <  10 K). Additionally, the effect of signal to noise ratio, lock-in frequency and lock-in bandwidth on temperature determination accuracy was studied in this work.

  19. A regularised boundary element formulation for contactless SAR evaluations within homogeneous and inhomogeneous head phantoms

    NASA Astrophysics Data System (ADS)

    Mitharwal, Rajendra; Andriulli, Francesco P.

    2015-11-01

    This work presents a Boundary Element Method (BEM) formulation for contactless electromagnetic field assessments. The new scheme is based on a regularised BEM approach that requires the use of electric measurements only. The regularisation is obtained by leveraging on an extension of Calderón techniques to rectangular systems leading to well-conditioned problems independent of the discretisation density. This enables the use of highly discretized Huygens surfaces that can be consequently placed very near to the radiating source. In addition, the new regularised scheme is hybridised with both surfacic homogeneous and volumetric inhomogeneous forward BEM solvers accelerated with fast matrix-vector multiplication schemes. This allows for rapid and effective dosimetric assessments and permits the use of inhomogeneous and realistic head phantoms. Numerical results corroborate the theory and confirms the practical effectiveness of all newly proposed formulations.

  20. Characterization of Cadmium-Zinc Telluride Crystals Grown by 'Contactless' PVT Using Synchrotron White Beam Topography

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Gillies, D.; Grasza, K.; Chung, H.; Raghothamachar, B.; Dudley, M.

    1997-01-01

    Crystals of Cd(1-x)Zn(x)Te grown by Physical Vapor Transport (PVT) using self-seeding 'contactless' techniques were characterized using synchrotron radiation (reflection, transmission, and Laue back-reflection X-ray topography). Crystals of low (x = 0.04) and high (up to x approx. = 0.4) ZnTe content were investigated. Twins and defects such as dislocations, precipitates, and slip bands were identified. Extensive inhomogeneous strains present in some samples were found to be generated by interaction (sticking) with the pedestal and by composition gradients in the crystals. Large (up to about 5 mm) oval strain fields were observed around some Te precipitates. Low angle grain boundaries were found only in higher ZnTe content (x greater than or equal to 0.2) samples.

  1. Nanoantenna harmonic sensor: theoretical analysis of contactless detection of molecules with light

    NASA Astrophysics Data System (ADS)

    Farhat, Mohamed; Cheng, Mark M. C.; Le, Khai Q.; Chen, Pai-Yen

    2015-10-01

    The nonlinear harmonic sensor is a popular wireless sensor and radiofrequency identification (RFID) technique, which allows high-performance sensing in a severe interference/clutter background by transmitting a radio wave and detecting its modulated higher-order harmonics. Here we introduce the concept and design of optical harmonic tags based on nonlinear nanoantennas that can contactlessly detect electronic (e.g. electron affinity) and optical (e.g. relative permittivity) characteristics of molecules. By using a dual-resonance gold-molecule-silver nanodipole antenna within the quantum mechanical realm, the spectral form of the second-harmonic scattering can sensitively reveal the physical properties of molecules, paving a new route towards optical molecular sensors and optical identification (OPID) of biological, genetic, and medical events for the ‘Internet of Nano-Things’.

  2. Nanoantenna harmonic sensor: theoretical analysis of contactless detection of molecules with light.

    PubMed

    Farhat, Mohamed; Cheng, Mark M C; Le, Khai Q; Chen, Pai-Yen

    2015-10-16

    The nonlinear harmonic sensor is a popular wireless sensor and radiofrequency identification (RFID) technique, which allows high-performance sensing in a severe interference/clutter background by transmitting a radio wave and detecting its modulated higher-order harmonics. Here we introduce the concept and design of optical harmonic tags based on nonlinear nanoantennas that can contactlessly detect electronic (e.g. electron affinity) and optical (e.g. relative permittivity) characteristics of molecules. By using a dual-resonance gold-molecule-silver nanodipole antenna within the quantum mechanical realm, the spectral form of the second-harmonic scattering can sensitively reveal the physical properties of molecules, paving a new route towards optical molecular sensors and optical identification (OPID) of biological, genetic, and medical events for the 'Internet of Nano-Things'.

  3. Contactless nondestructive method for determination of the carrier diffusion length in semiconductors and dielectrics

    NASA Astrophysics Data System (ADS)

    Manukhov, V. V.; Fedortsov, A. B.

    2017-03-01

    We propose the contactless nondestructive method for determination of the carrier diffusion length in semiconductors and dielectrics. The method is based on optical generation of non-equilibrium carriers at one point of the studied sample and the laser interference measurement of their concentration at another point. When changing the distance between these points, a decrease in the carrier concentration is observed. It depends on the carrier diffusion length, which is determined by comparing the experimental and theoretical dependences of the probe signal on the divergence of the injector and probe beams. We have studied silicon samples protected by an insulator layer and without any covering. The method can be used in scientific research and the electronics industry.

  4. Microfluidic diagnostic tool for the developing world: contactless impedance flow cytometry.

    PubMed

    Emaminejad, Sam; Javanmard, Mehdi; Dutton, Robert W; Davis, Ronald W

    2012-11-07

    In this work, we demonstrate a novel and cost-effective approach to implement a disposable microfluidic contactless impedance cytometer. Conventional methods for single cell impedance cytometry use microfabricated electrodes in direct contact with the buffer to measure changes of its electrical impedance when cells pass through the applied electric field. However, this approach requires expensive microfabrication of electrodes, and also, the fabricated electrodes cannot be reused without thorough and time-consuming cleaning process. Here, we introduce a novel approach to allow for single cell impedance cytometry using electrodes that can be reused, without the need for microfabrication of the electrodes. This disposable device can be potentially inserted onto a printed circuit board (PCB) which has a non-disposable, yet inexpensive, electronic reading apparatus. This significantly reduces the manufacturing costs, making it suitable for low resource settings, such as point-of-care testing in the developing countries.

  5. Microfluidic Diagnostic Tool for the Developing World: Contactless Impedance Flow Cytometry

    PubMed Central

    Emaminejad, Sam; Javanmard, Mehdi; Dutton, Robert W.; Davis, Ronald W.

    2012-01-01

    In this work, we demonstrate a novel and cost-effective approach to implement a disposable microfluidic contactless impedance cytometer. Conventional methods for single cell impedance cytometry use microfabricated electrodes in direct contact with the buffer to measure changes of its electrical impedance when cells pass through the applied electric field. However, this approach requires expensive microfabrication of electrodes, and also, the fabricated electrodes cannot be reused without thorough and time-consuming cleaning process. Here, we introduce a novel approach to allow for single cell impedance cytometry using electrodes that can be reused, without the need for microfabrication of the electrodes. This disposable device can be potentially inserted onto a Printed Circuit board (PCB) which has a non-disposable, yet inexpensive, electronic reading apparatus. This significantly reduces the manufacturing costs, making it suitable for low resource settings, such as point-of-care testing in the developing countries. PMID:22971813

  6. Contactless electroreflectance studies of II-VI nanostructures grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Muñoz, Martín; Lu, Hong; Guo, Shiping; Zhou, Xuecong; Tamargo, Maria C.; Pollak, Fred H.; Huang, Y. S.; Trallero-Giner, C.; Rodríguez, A. H.

    2004-02-01

    The interband transitions of a single quantum well structure of Zn0.53Cd0.47Se/Zn0.27Cd0.23Mg0.50Se, lattice matched to InP, and of a capped CdSe quantum dot structure have been investigated using contactless electroreflectance. From a comparison of the quantum well optical transitions with those calculated using the envelope function approximation we determined the band offsets for this system. The electroreflectance spectrum of the quantum dot structure shows transitions originating from all the portions of the sample including the quantum dots and the wetting layer. Assuming a lens shape geometry and that the effective height-to-radius ratio observed in uncapped quantum dots is preserved, the size of the capped quantum dots was determined using the observed electroreflectance transitions, and the effective mass approximation.

  7. Contactless measurement of critical current of high temperature superconductor tape by magnetic circuit.

    PubMed

    Gu, C; Qu, T-M; Zou, S-N; Han, Z

    2010-08-01

    A method based on the principle of the magnetic circuit is proposed and realized for contactless measurement of critical current (I(c)) of high temperature superconductor tapes. This method has two unique features: first, it eliminates noises caused by mechanical fluctuations and thus makes high speed and high stability measurement possible and second, adapts for both Bi(2)Si(2)Ca(2)Cu(3)O(x) (Bi2223) and YBa(2)Cu(3)O(7-x) (YBCO) tape, which even has a magnetic substrate. Theoretical analysis is given and an apparatus for the reel-to-reel measurement has been constructed, by which continuous inspection of I(c) uniformity of YBCO and Bi2223 tapes measured at different speeds is reported.

  8. Photoluminescence of CdTe Crystals Grown by Contactless PVT Method

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Grasza, K.; Cui, Y.; Wright, G.; Roy, U. N.; Burger, A.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    High quality CdTe crystals with resistivities higher than 10(exp 8) Omega cm were grown by the 'contactless' PVT (physical vapor transport) technique. Group III elements In and Al, and the transition metal Sc were introduced at the nominal level of about 6 ppm to the source material. Low-temperature photoluminescence (PL) has been employed to identify the origins of PL emissions of the crystals. It was found that the emission peaks at 1.584 eV and 1.581 eV exist only in the In-doped crystal. The result suggests that the luminescence line at 1.584 eV is associated with Cd-vacancy/indium complex. The intensity of the broadband centered at 1.43 eV decreases dramatically with introduction of Sc.

  9. Noninvasive induction implant heating: an approach for contactless altering of mechanical properties of shape memory implants.

    PubMed

    Pfeifer, Ronny; Hustedt, Michael; Wesling, Volker; Hurschler, Christoph; Olender, Gavin; Mach, Martin; Gösling, Thomas; Müller, Christian W

    2013-01-01

    This article shows an approach to change the properties of an orthopaedic shape memory implant within biological tissue, using contactless induction heating. Due to inducing the one way-memory effect, triggered by the rise of temperature within the implant, the geometry and hence the mechanical properties of the implant itself, are altered. The power uptake of the implant, depending on the induction parameters as well as on its position within the induction coil, is shown. Thermographic measurements are carried out in order to determine the surface temperature distribution of the implant. In order to simulate biological tissue, the implant was embedded in agarose gel. Suitable heating parameters, in terms of a short heating process in combination with a reduced heat impact on the surrounding environment, were determined. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  10. Design and performance of Sandia's contactless coilgun for 50 mm projectiles

    NASA Astrophysics Data System (ADS)

    Kaye, Ronald J.; Cnare, Eugene C.; Cowan, M.; Duggin, Billy W.; Lipinski, Ronald J.; Marder, Barry M.; Douglas, Gary M.; Shimp, Kenneth J.

    1991-10-01

    A multi-stage, contactless coilgun is being designed to demonstrate the applicability of this technology to accelerate nominal 50 mm (2 inch) diameter projectiles to velocities of 3 km/s. Forty stages of this design (Phase 1 coilgun) will provide a testbed for coil designs and system components while accelerating 200 to 400 gram projectiles to 1 km/s. We have successfully qualified the Phase 1 gun by operating 40 stages at half energy (10 kJ stored/stage) accelerating 340 gram, room-temperature, aluminum-armature projectiles to 406 m/s. We expect to accelerate 200 gram projectiles cooled to -196 C to three times this velocity when operating at full energy. This paper describes the design and performance of the Phase 1 coilgun and includes discussion of coil development, projectile design, capacitor banks, firing system, and integration.

  11. Monitoring gradient profile on-line in micro- and nano-high performance liquid chromatography using conductivity detection.

    PubMed

    Zhang, Min; Chen, Apeng; Lu, Joann J; Cao, Chengxi; Liu, Shaorong

    2016-08-19

    In micro- or nano-flow high performance liquid chromatography (HPLC), flow-splitters and gradient elutions are commonly used for reverse phase HPLC separations. When a flow splitter was used at a high split-ratio (e.g., 1000:1 or higher), the actual gradient may deviate away from the programmed gradient. Sometimes, mobile phase concentrations can deviate by as much as 5%. In this work, we noticed that the conductivity (σ) of a gradient decreased with the increasing organic-solvent fraction (φ). Based on the relationship between σ and φ, a method was developed for monitoring gradient profile on-line to record any deviations in these HPLC systems. The conductivity could be measured by a traditional conductivity detector or a capacitively coupled contactless conductivity detector (C(4)D). The method was applied for assessing the performance of an electroosmotic pump (EOP) based nano-HPLC. We also observed that σ value of the gradient changed with system pressure; a=0.0175ΔP (R(2)=0.964), where a is the percentage of the conductivity increase and ΔP is the system pressure in bar. This effect was also investigated.

  12. Functional coupling of TRPV4 cationic channel and large conductance, calcium-dependent potassium channel in human bronchial epithelial cell lines.

    PubMed

    Fernández-Fernández, José M; Andrade, Yaniré N; Arniges, Maite; Fernandes, Jacqueline; Plata, Cristina; Rubio-Moscardo, Francisca; Vázquez, Esther; Valverde, Miguel A

    2008-10-01

    Calcium-dependent potassium channels are implicated in electrolyte transport, cell volume regulation and mechanical responses in epithelia, although the pathways for calcium entry and their coupling to the activation of potassium channels are not fully understood. We now show molecular evidence for the presence of TRPV4, a calcium permeable channel sensitive to osmotic and mechanical stress, and its functional coupling to the large conductance calcium-dependent potassium channel (BK(Ca)) in a human bronchial epithelial cell line (HBE). Reverse transcriptase polymerase chain reaction, intracellular calcium imaging and whole-cell patch-clamp experiments using HBE cells demonstrated the presence of TRPV4 messenger and Ca(2+) entry, and outwardly rectifying cationic currents elicited by the TRPV4 specific activator 4alpha-phorbol 12,13-didecanoate (4alphaPDD). Cell-attached and whole-cell patch-clamp of HBE cells exposed to 4alphaPDD, and hypotonic and high-viscosity solutions (related to mechanical stress) revealed the activation of BK(Ca) channels subsequent to extracellular Ca(2+) influx via TRPV4, an effect lost upon antisense-mediated knock-down of TRPV4. Further analysis of BK(Ca) modulation after TRPV4 activation showed that the Ca(2+) signal can be generated away from the BK(Ca) location at the plasma membrane, and it is not mediated by intracellular Ca(2+) release via ryanodine receptors. Finally, we have shown that, unlike the reported disengagement of TRPV4 and BK(Ca) in response to hypotonic solutions, cystic fibrosis bronchial epithelial cells (CFBE) preserve the functional coupling of TRPV4 and BK(Ca) in response to high-viscous solutions.

  13. Contactless electroreflectance studies of the Fermi level position at the air/GaN interface: Bistable nature of the Ga-polar surface

    NASA Astrophysics Data System (ADS)

    Janicki, Łukasz; Gładysiewicz, Marta; Misiewicz, Jan; Klosek, Kamil; Sobanska, Marta; Kempisty, Paweł; Zytkiewicz, Zbigniew R.; Kudrawiec, Robert

    2017-02-01

    In this paper we show that the surface Fermi level of Ga-polar GaN exhibits a bistable behavior allowing it to be located at two distinct energetic positions at the air/GaN interface which is unusual for other III-V semiconductors such as GaAs or GaSb. To determine the Fermi level position at the air/GaN interface we perform contactless electroreflectance measurements on specially designed UD+ structures [GaN(undoped)/GaN(highly doped)/substrate] doped by Si and Mg. Analyzing the period of Franz-Keldysh oscillation we determine the built-in electric field in the undoped (U) layer. These studies coupled with numerical solutions of the Poisson equation allowed us to determine the position of the Fermi level at the air/GaN interface. We observe a change in the band bending correlated to different Fermi level positions in the doped (D+) layer. We show that depending on the doping type in the D+ layer the Fermi level at the air/GaN interface is located in the upper or lower singularity of surface density of states (SDOS) for Si or Mg doping of D+ layer, respectively. We support our findings with the density functional theory calculations of the SDOS and the dependence of the Fermi level position on the doping concentration in the bulk of a GaN slab.

  14. Molecular Orbital Rule for Quantum Interference in Weakly Coupled Dimers: Low-Energy Giant Conductivity Switching Induced by Orbital Level Crossing.

    PubMed

    Nozaki, Daijiro; Lücke, Andreas; Schmidt, Wolf Gero

    2017-02-16

    Destructive quantum interference (QI) in molecular junctions has attracted much attention in recent years. It can tune the conductance of molecular devices dramatically, which implies numerous potential applications in thermoelectric and switching applications. There are several schemes that address and rationalize QI in single molecular devices. Dimers play a particular role in this respect because the QI signal may disappear, depending on the dislocation of monomers. We derive a simple rule that governs the occurrence of QI in weakly coupled dimer stacks of both alternant and nonalternant polyaromatic hydrocarbons (PAHs) and extends the Tada-Yoshizawa scheme. Starting from the Green's function formalism combined with the molecular orbital expansion approach, it is shown that QI-induced antiresonances and their energies can be predicted from the amplitudes of the respective monomer terminal molecular orbitals. The condition is illustrated for a toy model consisting of two hydrogen molecules and applied within density functional calculations to alternant dimers of oligo(phenylene-ethynylene) and nonalternant PAHs. Minimal dimer structure modifications that require only a few millielectronvolts and lead to an energy crossing of the essentially preserved monomer orbitals are shown to result in giant conductance switching ratios.

  15. NMR Evidences of the Coupling between Conduction Electrons and Molecular Degrees of Freedom in the Exotic Member of the Bechgaard Salt (TMTSF)2FSO3

    NASA Astrophysics Data System (ADS)

    Satsukawa, Hidetaka; Yajima, Akio; Hiraki, Ko-ichi; Takahashi, Toshihiro; Kang, Haeyong; Jo, Younjung; Kang, Woun; Chung, Ok-Hee

    2016-12-01

    We performed 77Se- and 19F-NMR measurements on single crystals of (TMTSF)2FSO3 to characterize the electronic structures of different phases in the temperature-pressure phase diagram, determined by precise transport measurements [Jo et al., Phys. Rev. B 67, 014516 (2003)]. We claim that such varieties of electronic states in the refined phase diagram are caused by strong couplings of the conduction electrons with FSO3 anions, especially with the permanent electric dipoles on the anions. We suggest that as temperature decreases, the FSO3 anions form orientational ordering through two steps; first, only the tetrahedrons form an orientational order leaving the orientations of the electronic dipoles in random (transition I); then the dipoles form a perfect orientational order at a lower temperature (transition II). In the intermediate temperature range between transitions I and II, we found an appreciable enhancement of homogeneous and inhomogeneous widths of the 77Se-NMR spectrum. From the analysis of the angular dependence of the linewidth, we attributed these anomalies to the intramolecular charge disproportionation or imbalance and its slow dynamics caused by the coupling with the permanent electric dipole of the anion. Results of 19F-NMR relaxation and lineshape measurements support this picture very well. Electronic structures at higher pressures up to 1.25 GPa are discussed on the basis of the results of the 77Se- and 19F-NMR measurements.

  16. Overwash Deposition Stabilizes Backbarrier Marshes as Sea Level Rises: Insights from Experiments Conducted using a Coupled Barrier Island-Marsh Model

    NASA Astrophysics Data System (ADS)

    Walters, D.; Moore, L. J.; Duran, O.; Fagherazzi, S.; Mariotti, G.

    2013-12-01

    We investigate the interactions between barrier islands and backbarrier marshes that determine the island-marsh response to climate change. To this end we couple the morphological-behavior model, GEOMBEST, with a newly-developed marsh-edge progradation component based on an existing model of tidal flat-salt marsh hydrodynamics. We conduct two sets of experiments with the new model to assess 1) the impact of overwash deposition on backbarrier marsh morphology and 2) the impact of backbarrier marsh morphology on rates of island migration. Results indicate that for backbarrier marshes to persist under accelerating RSLR, sufficient sediment must be deposited at the bayside marsh-edge boundary for the marsh to prograde at a rate equal to or greater than the rate of island transgression (i.e., to maintain marsh width). Simulations further indicate that overwash deposition can provide backbarrier marshes with an additional source of sediment that allows maintenance of existing (i.e., a steady state), and creation of new, narrow marsh platforms (~500m wide) within a range of conditions (high rate of RSLR and low fine-grained sediment supply) under which they would otherwise disappear or not exist. This existence of a stable marsh width is supported by remote sensing observations of barrier islands and backbarrier marshes along the eastern shore of Virginia, which show that a significantly high proportion of islands are backed by marshes approximately 500m wide. A second set of experiments demonstrates that the impact of backbarrier marsh platforms on barrier islands is to reduce accommodation space in the backbarrier bay, which decreases the rate of island transgression because less landward migration is necessary to maintain island elevation relative to sea level. These coupled processes indicate that barrier islands and backbarrier marshes are intimately connected such that under conditions of high rates of RSLR and overwash deposition, narrow marsh platforms exist where

  17. New concept using Passive Infrared (PIR) technology for a contactless detection of breathing movement: a pilot study involving a cohort of 169 adult patients.

    PubMed

    Hers, V; Corbugy, D; Joslet, I; Hermant, P; Demarteau, J; Delhougne, B; Vandermoten, G; Hermanne, J P

    2013-10-01

    A pilot study has been conducted to validate the Breath Motion Detecting System (BMDS), a new concept using Passive Infrared (PIR) technology for a contactless detection of respiratory movements. The primary objective of the study was to show if movements detected during sleep by the BMDS were indeed related to breathing. This medical device is not intended to measure the respiratory rate, but in a second step, it will be able to detect pathological central apnea in adults. One hundred and sixty-nine adult patients underwent a full polysomnography in which each respiratory movement was recorded concomitantly through the BMDS. Curves obtained by the BMDS were compared to those of thoracic movements recorded by classical piezoelectric belts and of pressure obtained with nasal cannula. The correlations between the PIR sensors were highly indicative of respiratory movement detection. Since PIR sensors are sensitive only to the exemplification of the rib cage, they did not detect obstructive apnea. Unfortunately, only a few patients in the studied population had a central apnea. Moreover as our sleep laboratory was equipped only with piezoelectric bands, the central apnea respiratory effort data are not a validated signal to be used during sleep recordings. The data recorded by the BMDS demonstrate the ability of the PIR technology to detect respiratory movements in adults. The concept is practical, inexpensive and safe for the patient. Further studies with respiratory inductive plethysmography are needed to investigate the potential of BMDS to detect central apneas.

  18. Inverse Estimation of Parameters for a Coupled Photosynthesis and Stomatal Conductance Model Using Eddy Covariance Measurements at a Black Spruce Forest in Alaska

    NASA Astrophysics Data System (ADS)

    Ueyama, M.; Tahara, N.; Iwata, H.; Nagano, H.; Harazono, Y.

    2014-12-01

    For better understanding high-latitude carbon and water cycles, parameters of a coupled photosynthesis and stomatal conductance big-leaf model (Farquhar et al., 1980; Ball and Berry, 1987; Baldocchi, 1994) were inversely estimated using gross primary productivity (GPP) and evapotranspiration by eddy covariance measurements at a black spruce forest in interior Alaska (Iwata et al., 2012; Ueyama et al., 2014). We developed a sequential optimization method based on a global optimization technique; shuffled complex evolution (SCE-UA) method (Duan et al., 1993). First, photosynthetic parameters (maximum carboxylation and maximum electron transfer rate at 25oC; Vcmax25 and Jmax25) were optimized for GPP, and then stomatal conductance parameters (m and b in the Ball-Berry model) were optimized for evapotranspiration. Based on our optimization, Vcmax25, Jmax25, and m varied seasonally, but b value was almost constant throughout seasons. Vcmax25 and Jmax25 were higher in summer months than other months, which related to understory leaf area index. m was higher in winter months than other months, but did not significantly change throughout the growing season. Our results indicated that simulations using constant ecophysiological parameters could underestimate photosynthesis and evapotranspiration of high-latitude ecosystems. References Ball and Berry, 1987: Progress in Photosynthesis Research, pp 221-224. Baldocchi, 1994: Tree Physiol., 14, 1069-1079. Duan et al., 1993: J. Optimization Theory and Applications, 76, 501-521. Farquhar et al., 1980: Planta, 149, 78-90. Iwata et al., 2012: Agric. For. Meteorol., 161, 107-115. Ueyama et al., 2014: Global Change Biol., 20, 1161-1173.

  19. Doping of a dielectric layer as a new alternative for increasing sensitivity of the contactless conductivity detection in microchips.

    PubMed

    Lima, Renato Sousa; Segato, Thiago Pinotti; Gobbi, Angelo Luiz; Coltro, Wendell Karlos Tomazelli; Carrilho, Emanuel

    2011-12-21

    This communication describes a new procedure to increase the sensitivity of C(4)D in PDMS/glass microchips. The method consists in doping the insulating layer (PDMS) over the electrodes with nanoparticles of TiO(2), increasing thus its dielectric constant. The experimental protocol is simple, inexpensive, and fast.

  20. Cell-to-cell coupling in engineered pairs of rat ventricular cardiomyocytes: relation between Cx43 immunofluorescence and intercellular electrical conductance

    PubMed Central

    McCain, Megan L.; Desplantez, Thomas; Geisse, Nicholas A.; Rothen-Rutishauser, Barbara; Oberer, Helene; Parker, Kevin Kit

    2012-01-01

    Gap junctions are composed of connexin (Cx) proteins, which mediate intercellular communication. Cx43 is the dominant Cx in ventricular myocardium, and Cx45 is present in trace amounts. Cx43 immunosignal has been associated with cell-to-cell coupling and electrical propagation, but no studies have directly correlated Cx43 immunosignal to electrical cell-to-cell conductance, gj, in ventricular cardiomyocyte pairs. To assess the correlation between Cx43 immunosignal and gj, we developed a method to determine both parameters from the same cell pair. Neonatal rat ventricular cardiomyocytes were seeded on micropatterned islands of fibronectin. This allowed formation of cell pairs with reproducible shapes and facilitated tracking of cell pair locations. Moreover, cell spreading was limited by the fibronectin pattern, which allowed us to increase cell height by reducing the surface area of the pattern. Whole cell dual voltage clamp was used to record gj of cell pairs after 3–5 days in culture. Fixation of cell pairs before removal of patch electrodes enabled preservation of cell morphology and offline identification of patched pairs. Subsequently, pairs were immunostained, and the volume of junctional Cx43 was quantified using confocal microscopy, image deconvolution, and three-dimensional reconstruction. Our results show a linear correlation between gj and Cx43 immunosignal within a range of 8–50 nS. PMID:22081700

  1. Modelling transient heat conduction in solids at multiple length and time scales: A coupled non-equilibrium molecular dynamics/continuum approach

    SciTech Connect

    Jolley, Kenny; Gill, Simon P.A.

    2009-10-20

    A method for controlling the thermal boundary conditions of non-equilibrium molecular dynamics simulations is presented. The method is simple to implement into a conventional molecular dynamics code and independent of the atomistic model employed. It works by regulating the temperature in a thermostatted boundary region by feedback control to achieve the desired temperature at the edge of an inner region where the true atomistic dynamics are retained. This is necessary to avoid intrinsic boundary effects in non-equilibrium molecular dynamics simulations. Three thermostats are investigated: the global deterministic Nose-Hoover thermostat and two local stochastic thermostats, Langevin and stadium damping. The latter thermostat is introduced to avoid the adverse reflection of phonons that occurs at an abrupt interface. The method is then extended to allow atomistic/continuum models to be thermally coupled concurrently for the analysis of large steady state and transient heat conduction problems. The effectiveness of the algorithm is demonstrated for the example of heat flow down a three-dimensional atomistic rod of uniform cross-section subjected to a variety of boundary conditions.

  2. Palmprint and face score level fusion: hardware implementation of a contactless small sample biometric system

    NASA Astrophysics Data System (ADS)

    Poinsot, Audrey; Yang, Fan; Brost, Vincent

    2011-02-01

    Including multiple sources of information in personal identity recognition and verification gives the opportunity to greatly improve performance. We propose a contactless biometric system that combines two modalities: palmprint and face. Hardware implementations are proposed on the Texas Instrument Digital Signal Processor and Xilinx Field-Programmable Gate Array (FPGA) platforms. The algorithmic chain consists of a preprocessing (which includes palm extraction from hand images), Gabor feature extraction, comparison by Hamming distance, and score fusion. Fusion possibilities are discussed and tested first using a bimodal database of 130 subjects that we designed (uB database), and then two common public biometric databases (AR for face and PolyU for palmprint). High performance has been obtained for recognition and verification purpose: a recognition rate of 97.49% with AR-PolyU database and an equal error rate of 1.10% on the uB database using only two training samples per subject have been obtained. Hardware results demonstrate that preprocessing can easily be performed during the acquisition phase, and multimodal biometric recognition can be treated almost instantly (0.4 ms on FPGA). We show the feasibility of a robust and efficient multimodal hardware biometric system that offers several advantages, such as user-friendliness and flexibility.

  3. Dielectrophoretic differentiation of mouse ovarian surface epithelial cells, macrophages, and fibroblasts using contactless dielectrophoresis

    PubMed Central

    Salmanzadeh, Alireza; Kittur, Harsha; Sano, Michael B.; C. Roberts, Paul; Schmelz, Eva M.; Davalos, Rafael V.

    2012-01-01

    Ovarian cancer is the leading cause of death from gynecological malignancies in women. The primary challenge is the detection of the cancer at an early stage, since this drastically increases the survival rate. In this study we investigated the dielectrophoretic responses of progressive stages of mouse ovarian surface epithelial (MOSE) cells, as well as mouse fibroblast and macrophage cell lines, utilizing contactless dielectrophoresis (cDEP). cDEP is a relatively new cell manipulation technique that has addressed some of the challenges of conventional dielectrophoretic methods. To evaluate our microfluidic device performance, we computationally studied the effects of altering various geometrical parameters, such as the size and arrangement of insulating structures, on dielectrophoretic and drag forces. We found that the trapping voltage of MOSE cells increases as the cells progress from a non-tumorigenic, benign cell to a tumorigenic, malignant phenotype. Additionally, all MOSE cells display unique behavior compared to fibroblasts and macrophages, representing normal and inflammatory cells found in the peritoneal fluid. Based on these findings, we predict that cDEP can be utilized for isolation of ovarian cancer cells from peritoneal fluid as an early cancer detection tool. PMID:22536308

  4. Electromagnet weight reduction in a magnetic levitation system for contactless delivery applications.

    PubMed

    Hong, Do-Kwan; Woo, Byung-Chul; Koo, Dae-Hyun; Lee, Ki-Chang

    2010-01-01

    This paper presents an optimum design of a lightweight vehicle levitation electromagnet, which also provides a passive guide force in a magnetic levitation system for contactless delivery applications. The split alignment of C-shaped electromagnets about C-shaped rails has a bad effect on the lateral deviation force, therefore, no-split positioning of electromagnets is better for lateral performance. This is verified by simulations and experiments. This paper presents a statistically optimized design with a high number of the design variables to reduce the weight of the electromagnet under the constraint of normal force using response surface methodology (RSM) and the kriging interpolation method. 2D and 3D magnetostatic analysis of the electromagnet are performed using ANSYS. The most effective design variables are extracted by a Pareto chart. The most desirable set is determined and the influence of each design variable on the objective function can be obtained. The generalized reduced gradient (GRG) algorithm is adopted in the kriging model. This paper's procedure is validated by a comparison between experimental and calculation results, which shows that the predicted performance of the electromagnet designed by RSM is in good agreement with the simulation results.

  5. Electromagnet Weight Reduction in a Magnetic Levitation System for Contactless Delivery Applications

    PubMed Central

    Hong, Do-Kwan; Woo, Byung-Chul; Koo, Dae-Hyun; Lee, Ki-Chang

    2010-01-01

    This paper presents an optimum design of a lightweight vehicle levitation electromagnet, which also provides a passive guide force in a magnetic levitation system for contactless delivery applications. The split alignment of C-shaped electromagnets about C-shaped rails has a bad effect on the lateral deviation force, therefore, no-split positioning of electromagnets is better for lateral performance. This is verified by simulations and experiments. This paper presents a statistically optimized design with a high number of the design variables to reduce the weight of the electromagnet under the constraint of normal force using response surface methodology (RSM) and the kriging interpolation method. 2D and 3D magnetostatic analysis of the electromagnet are performed using ANSYS. The most effective design variables are extracted by a Pareto chart. The most desirable set is determined and the influence of each design variable on the objective function can be obtained. The generalized reduced gradient (GRG) algorithm is adopted in the kriging model. This paper’s procedure is validated by a comparison between experimental and calculation results, which shows that the predicted performance of the electromagnet designed by RSM is in good agreement with the simulation results. PMID:22163572

  6. Ventilation and Heart Rate Monitoring in Drivers using a Contactless Electrical Bioimpedance System

    NASA Astrophysics Data System (ADS)

    Macías, R.; García, M. A.; Ramos, J.; Bragós, R.; Fernández, M.

    2013-04-01

    Nowadays, the road safety is one of the most important priorities in the automotive industry. Many times, this safety is jeopardized because of driving under inappropriate states, e.g. drowsiness, drugs and/or alcohol. Therefore several systems for monitoring the behavior of subjects during driving are researched. In this paper, a device based on a contactless electrical bioimpedance system is shown. Using the four-wire technique, this system is capable of obtaining the heart rate and the ventilation of the driver through multiple textile electrodes. These textile electrodes are placed on the car seat and the steering wheel. Moreover, it is also reported several measurements done in a controlled environment, i.e. a test room where there are no artifacts due to the car vibrations or the road state. In the mentioned measurements, the system response can be observed depending on several parameters such as the placement of the electrodes or the number of clothing layers worn by the driver.

  7. Contactless Acoustic Manipulation and Sorting of Particles by Dynamic Acoustic Fields.

    PubMed

    Andrade, Marco Aurelio; Skotis, George D; Ritchie, Scott; Cumming, David R S; Riehle, Mathis O; Bernassau, Anne L

    2016-09-12

    This paper presents a contactless, acoustic technique to manipulate and sort particles of varying size in both liquid and air media. An acoustic standing wave is generated by the superposition of counter-propagating waves emitted by two opposing emitters. The acoustic radiation force traps the smallest particles at the pressure nodes of the acoustic standing wave. The position of the particles can be manipulated by dynamically changing the phase difference between the two emitters. By applying a dynamic acoustic field (DAF), it is demonstrated that particles can be manipulated spatially and sorted according to size. The discrimination (sorting dynamic range) capability is initially demonstrated in liquid media by separating three different sets of polystyrene particles, ranging in size from 5 to 45 μm in diameter. The separation between particles was performed up to a ratio of 5/6 in diameter (20 % diameter difference). Finally, the scalability of the DAF method is demonstrated by sorting expanded polystyrene particles of 2 and 5 mm diameter in air.

  8. Precise, contactless measurements of the surface tension of picolitre aerosol droplets.

    PubMed

    Bzdek, Bryan R; Power, Rory M; Simpson, Stephen H; Reid, Jonathan P; Royall, C Patrick

    2016-01-01

    The surface composition and surface tension of aqueous droplets can influence key aerosol characteristics and processes including the critical supersaturation required for activation to form cloud droplets in the atmosphere. Despite its fundamental importance, surface tension measurements on droplets represent a considerable challenge owing to their small volumes. In this work, we utilize holographic optical tweezers to study the damped surface oscillations of a suspended droplet (<10 μm radius) following the controlled coalescence of a pair of droplets and report the first contactless measurements of the surface tension and viscosity of droplets containing only 1-4 pL of material. An advantage of performing the measurement in aerosol is that supersaturated solute states (common in atmospheric aerosol) may be accessed. For pairs of droplets starting at their equilibrium surface composition, surface tensions and viscosities are consistent with bulk equilibrium values, indicating that droplet surfaces respond to changes in surface area on microsecond timescales and suggesting that equilibrium values can be assumed for growing atmospheric droplets. Furthermore, droplet surfaces are shown to be rapidly modified by trace species thereby altering their surface tension. This equilibration of droplet surface tension to the local environmental conditions is illustrated for unknown contaminants in laboratory air and also for droplets exposed to gas passing through a water-ethanol solution. This approach enables precise measurements of surface tension and viscosity over long time periods, properties that currently are poorly constrained.

  9. A Method Using Optical Contactless Displacement Sensors to Measure Vibration Stress of Small-Bore Piping.

    PubMed

    Maekawa, Akira; Tsuji, Takashi; Takahashi, Tsuneo; Noda, Michiyasu

    2014-02-01

    In nuclear power plants, vibration stress of piping is frequently evaluated to prevent fatigue failure. A simple and fast measurement method is attractive to evaluate many piping systems efficiently. In this study, a method to measure the vibration stress using optical contactless displacement sensors was proposed, the prototype instrument was developed, and the instrument practicality for the method was verified. In the proposed method, light emitting diodes (LEDs) were used as measurement sensors and the vibration stress was estimated by measuring the deformation geometry of the piping caused by oscillation, which was measured as the piping curvature radius. The method provided fast and simple vibration estimates for small-bore piping. Its verification and practicality were confirmed by vibration tests using a test pipe and mock-up piping. The stress measured by both the proposed method and an accurate conventional method using strain gauges were in agreement, and it was concluded that the proposed method could be used for actual plant piping systems.

  10. Wearable Contactless Respiration Sensor Based on Multi-Material Fibers Integrated into Textile.

    PubMed

    Guay, Philippe; Gorgutsa, Stepan; LaRochelle, Sophie; Messaddeq, Younes

    2017-05-06

    In this paper, we report on a novel sensor for the contactless monitoring of the respiration rate, made from multi-material fibers arranged in the form of spiral antenna (2.45 GHz central frequency). High flexibility of the used composite metal-glass-polymer fibers permits their integration into a cotton t-shirt without compromising comfort or restricting movement of the user. At the same time, change of the antenna geometry, due to the chest expansion and the displacement of the air volume in the lungs, is found to cause a significant shift of the antenna operational frequency, thus allowing respiration detection. In contrast with many current solutions, respiration is detected without attachment of the electrodes of any kind to the user's body, neither direct contact of the fiber with the skin is required. Respiration patterns for two male volunteers were recorded with the help of a sensor prototype integrated into standard cotton t-shirt in sitting, standing, and lying scenarios. The typical measured frequency shift for the deep and shallow breathing was found to be in the range 120-200 MHz and 10-15 MHz, respectively. The same spiral fiber antenna is also shown to be suitable for short-range wireless communication, thus allowing respiration data transmission, for example, via the Bluetooth protocol, to mobile handheld devices.

  11. A machine learning approach to improve contactless heart rate monitoring using a webcam.

    PubMed

    Monkaresi, Hamed; Calvo, Rafael A; Yan, Hong

    2014-07-01

    Unobtrusive, contactless recordings of physiological signals are very important for many health and human-computer interaction applications. Most current systems require sensors which intrusively touch the user's skin. Recent advances in contact-free physiological signals open the door to many new types of applications. This technology promises to measure heart rate (HR) and respiration using video only. The effectiveness of this technology, its limitations, and ways of overcoming them deserves particular attention. In this paper, we evaluate this technique for measuring HR in a controlled situation, in a naturalistic computer interaction session, and in an exercise situation. For comparison, HR was measured simultaneously using an electrocardiography device during all sessions. The results replicated the published results in controlled situations, but show that they cannot yet be considered as a valid measure of HR in naturalistic human-computer interaction. We propose a machine learning approach to improve the accuracy of HR detection in naturalistic measurements. The results demonstrate that the root mean squared error is reduced from 43.76 to 3.64 beats/min using the proposed method.

  12. Contactless vision-based pulse rate detection of Infants Under Neurological Examinations.

    PubMed

    Sikdar, Arindam; Behera, Santosh Kumar; Dogra, Debi Prosad; Bhaskar, Harish

    2015-08-01

    In this paper, we propose a method for detecting variations in the Pulse Rate (PR) of infants undergoing the Hammersmith Infant Neurological Examinations (HINE) using video data. As in every other medical examination the measurement of the PR is critical to underpin the physiological state of living beings. During HINE, measuring the infant's PR is important as its variations against physical conditions, age and other factors must be studied and correlated against developmental scores. However, this becomes highly complicated with active infants where their movements often lead to inconsistent PR estimation. We propose the use of a non-linear dimensionality reduction technique, called Laplacian Eigenmap (LE), to uncover the pulse information encapsulated within the high dimensional visual manifold characterized by normalized RGB feature vectors. Furthermore, low-level image filtering is applied to accurately detect PR within a chosen region-of-interest (ROI) from different parts of the infant's body. For validation and analysis, a set of 14 video sequences of infants undergoing five important tests of HINE have been chosen. Experimental results suggest that a bi-parametrized combination of color features from the RG and GB channels provide more valuable information in comparison to the RB and RGB channels. Results have demonstrated that this contactless method of PR detection has promising prospects for its future use in other clinical examinations of infants.

  13. Contactless inductive flow tomography: basic principles and first applications in the experimental modelling of continuous casting

    NASA Astrophysics Data System (ADS)

    Stefani, F.; Eckert, S.; Ratajczak, M.; Timmel, K.; Wondrak, T.

    2016-07-01

    Contactless inductive flow tomography (CIFT) aims at reconstructing the flow structure of a liquid metal from the magnetic fields measured at various positions outside the fluid body which are induced by the flow under the influence of one or multiple applied magnetic fields. We recap the basic mathematical principles of CIFT and the results of an experiment in which the propeller-driven three-dimensional flow in a cylindrical had been reconstructed. We also summarize the recent activities to utilize CIFT in various problems connected with the experimental simulation of the continuous casting process. These include flow reconstructions in single-phase and two-phase flow problems in the Mini-LIMMCAST model of slab-casting, studies of the specific effects of an electromagnetic stirrer attached to the Submerged Entry Nozzle (SEN), as well as first successful applications of CIFT on the background of a strong electromagnetic brake field. We conclude by discussing some remaining obstacles for the deployment of CIFT in a real caster.

  14. Contactless microwave study of dispersive transport in thin film CdSe

    NASA Astrophysics Data System (ADS)

    Grabtchak, Serguei Yu; Cocivera, Michael

    1996-01-01

    The contactless microwave technique was used to measure light-induced transients in the power absorbed by thin films of polycrystalline CdSe. Because the rise time of the microwave cavity was 60 ns, the analysis was limited to 100 ns or longer. Measurement of these transients at a number of fixed frequencies across the ``dark'' resonance frequency made reconstruction of the difference signal possible. This signal, which represents the difference between the ``dark'' and ``light'' Lorentz resonance curves, was determined at various times during the decay. Analysis of these signals provided the time dependence for the changes in the real and imaginary parts of the dielectric constant, which correspond to the densities of the trapped and free electrons. The decays of these parameters were characterized by three time domains. At the shortest times, the two parameters did not have the same time dependence. At intermediate times, the densities of both the trapped and free electrons had the same time dependence characterized by a power law decay, and a mechanism consistent with these results involves rapid equilibration between the free electrons and those in the shallow traps. Decay in this region was consistent with a dispersive transport mechanism. Intensity effects indicate saturation of the shallow traps. The third region occurred at the break in the power law dependence indicating a bimolecular recombination process. Measurements at higher temperatures indicate a change from a bimolecular to a monomolecular recombination mechanism.

  15. Wearable Contactless Respiration Sensor Based on Multi-Material Fibers Integrated into Textile

    PubMed Central

    Guay, Philippe; Gorgutsa, Stepan; LaRochelle, Sophie; Messaddeq, Younes

    2017-01-01

    In this paper, we report on a novel sensor for the contactless monitoring of the respiration rate, made from multi-material fibers arranged in the form of spiral antenna (2.45 GHz central frequency). High flexibility of the used composite metal-glass-polymer fibers permits their integration into a cotton t-shirt without compromising comfort or restricting movement of the user. At the same time, change of the antenna geometry, due to the chest expansion and the displacement of the air volume in the lungs, is found to cause a significant shift of the antenna operational frequency, thus allowing respiration detection. In contrast with many current solutions, respiration is detected without attachment of the electrodes of any kind to the user’s body, neither direct contact of the fiber with the skin is required. Respiration patterns for two male volunteers were recorded with the help of a sensor prototype integrated into standard cotton t-shirt in sitting, standing, and lying scenarios. The typical measured frequency shift for the deep and shallow breathing was found to be in the range 120–200 MHz and 10–15 MHz, respectively. The same spiral fiber antenna is also shown to be suitable for short-range wireless communication, thus allowing respiration data transmission, for example, via the Bluetooth protocol, to mobile handheld devices. PMID:28481252

  16. Development of Audio Watermark Technology to be Extracted Contactlessly by Cell Phone

    NASA Astrophysics Data System (ADS)

    Modegi, Toshio

    We have proposed a novel audio watermarking technology, which embeds a set of bitstream data by changing two-channel stereo locations of lower frequency components in an embedding target audio signal. This method features nearly lossless embedding, robustness against lossy data compression or analogue conversion, and enables contactless asynchronous detection of embedded watermarks through speaker and microphone devices without the original audio signals. Then, we propose several extended monaural embedding methods, which embed data by changing level balances between two sets of lower frequency components, which are divided by either frequency or temporal dimensions. In these level changes, we remove lower frequency components of the left channel signal and add the removed components to the corresponding components of the right channel of given stereo signal in order to support also nearly lossless embedding. These methods enable watermark detection from only the left channel signal by a single monaural microphone, and we have confirmed detection capability by a cell phone. In this paper, we describe abstracts of our proposed watermark embedding and extracting algorithms, experimental results of watermark extraction precision.

  17. Monitoring of Weekly Sleep Pattern Variations at Home with a Contactless Biomotion Sensor

    PubMed Central

    Hashizaki, Masanori; Nakajima, Hiroshi; Kume, Kazuhiko

    2015-01-01

    Many people find that their sleep is restricted or disturbed by social obligations, including work. Sleep phase delays can affect an individual’s circadian rhythms on the following day and cause daytime sleepiness and/or poor performance. In this study, to examine weekly variations in sleep patterns, we analyzed sleep data for seven-day periods (from Sunday to Saturday) that had been collected from 2914 subjects (aged 20–79 years) over a total of 24,899 subject-weeks using contactless biomotion sensors. On the weekend, the subjects’ mean sleep midpoint, bedtime, and wake-up time were delayed by 40, 26 and 53 min, respectively, compared with those seen on weekdays. In addition, on weekdays, the mean difference between the maximum and median sleep midpoint ranged from 35 to 47 min among the subjects in their 20 s–70 s. The weekend delay and weekday variation in the subjects’ sleep patterns tended to decrease with age. This study detected sleep pattern disturbances on both weekdays and weekends. The serial changes in weekday bedtimes detected in this study suggest that sleep habits are influenced by changes in the temporal patterns of social activities/duties. We need further study the advantages of getting extra sleep and the disadvantages of sleep pattern disturbances in daily lifestyle. PMID:26247948

  18. Optimized design of a micromachined G-switch based on contactless configuration for health care applications

    NASA Astrophysics Data System (ADS)

    Ongkodjojo, Andojo; Tay, Francis E. H.

    2006-04-01

    This paper proposes design concept and fundamentals of a novel acceleration microswitch (G-switch), which is an integration of bimorph actuator and field effect transistor (FET). This micro-switch can be used to actuate the alarm system for call for helps - minimizing injuries after the fall among elderly; or trigger the air-inflatable hip protector for the fall prevention. The device can be attached to the developed MEMS-Wear smart shirt. Its structural design and switching FET are optimized using the global optimization method so that the bimorph as a movable gate can collapse on the gate insulating layer, when there is an impact force, which is greater than a threshold value (experimentally found to be 4.8g based on the previously published report). This contactless mechanism optimizes the field effect between the bimorph and the substrate causing an electrical current flow profusely with a sensitivity of 0.1 mA/V2 with a FET's ratio of ~19. The device will consume less power as the gate to source voltage (VGS) can be applied up to 4 V. All design parameters must satisfy the specified design constraints. In future, the optimized design will be fabricated and incorporated into the smart shirt for testing upon the fall events.

  19. Contactless optical fiber refractive index sensor for liquid and solid samples

    NASA Astrophysics Data System (ADS)

    Moreno-Hernández, Carlos; Monzón-Hernández, D.; Villatoro, Joel

    2016-05-01

    We report on a contactless optical fiber refractive index (RI) sensor that can be used to measure the RI of solid or liquid samples. The sensor is simple to construct and consists of a Fabry-Perot interferometer (FPI) with long cavity. The cavity of our FPI consists of a tapered optical fiber tip and an external flat mirror. The output beam of the fiber tip is partially reflected from different interfaces of the sample present in the interferometer cavity. Each of such reflections interferes with the beam internally reflected by the fiber tip. Thus, a multiple-beam FPI is formed whose reflection spectrum is composed by the superposition of several two-beam interferences. The analysis of the multiple interference spectra was carried out in the Fourier domain. Several glass samples, water-sucrose and water-glycerol solutions were prepared and tested. Since the fiber tip is not in direct contact with the sample under test the measurement is simple and immediate. To our-knowledge, this is the first time that a fiber optic sensor can be used to measure the RI of solid and liquid samples without any modification.

  20. Instantaneous-to-daily GPP upscaling schemes based on a coupled photosynthesis-stomatal conductance model: correcting the overestimation of GPP by directly using daily average meteorological inputs.

    PubMed

    Wang, Fumin; Gonsamo, Alemu; Chen, Jing M; Black, T Andrew; Zhou, Bin

    2014-11-01

    Daily canopy photosynthesis is usually temporally upscaled from instantaneous (i.e., seconds) photosynthesis rate. The nonlinear response of photosynthesis to meteorological variables makes the temporal scaling a significant challenge. In this study, two temporal upscaling schemes of daily photosynthesis, the integrated daily model (IDM) and the segmented daily model (SDM), are presented by considering the diurnal variations of meteorological variables based on a coupled photosynthesis-stomatal conductance model. The two models, as well as a simple average daily model (SADM) with daily average meteorological inputs, were validated using the tower-derived gross primary production (GPP) to assess their abilities in simulating daily photosynthesis. The results showed IDM closely followed the seasonal trend of the tower-derived GPP with an average RMSE of 1.63 g C m(-2) day(-1), and an average Nash-Sutcliffe model efficiency coefficient (E) of 0.87. SDM performed similarly to IDM in GPP simulation but decreased the computation time by >66%. SADM overestimated daily GPP by about 15% during the growing season compared to IDM. Both IDM and SDM greatly decreased the overestimation by SADM, and improved the simulation of daily GPP by reducing the RMSE by 34 and 30%, respectively. The results indicated that IDM and SDM are useful temporal upscaling approaches, and both are superior to SADM in daily GPP simulation because they take into account the diurnally varying responses of photosynthesis to meteorological variables. SDM is computationally more efficient, and therefore more suitable for long-term and large-scale GPP simulations.

  1. Determination of the magnetic permeability and electrical conductivity of material of tubular products

    SciTech Connect

    Bashtannikov, L.A.; Sebko, V.P.; Tyupa, V.I.

    1986-01-01

    This paper suggests a method of contactless measurement with ac of the magnetic permeability and electrical conductivity of the material of tubular products. The possibilities of the method in question were experimentally verified. The two-parameter method was used for sorting low-melting and steel drilling pipes. Determining the strength characteristics of drilling pipes jointly from two parameters increases the reliability of scrapping procedures.

  2. A contactless positioning system for monitoring discontinuities in three dimensions with geological and geotechnical applications

    NASA Astrophysics Data System (ADS)

    Rinaldi-Montes, Natalia; Rowberry, Matt; Frontera, Carlos; BaroÅ, Ivo; Garcés, Javier; Blahůt, Jan; Pérez-López, Raúl; Pennos, Christos; Martí, Xavi

    2017-07-01

    In this paper, a contactless positioning system is presented which has been designed to monitor the kinematic behavior of mechanical discontinuities in three dimensions. The positioning system comprises a neodymium magnet, fixed on one side of a discontinuity, and a magnetoresistive sensing array, fixed on the opposing side. Each of the anisotropic magnetoresistive sensors in the sensing array records the magnetic field along three orthogonal directions. The positioning system intrinsically generates compact data packages which are transmitted effectively using a range of standard wireless telecommunication technologies. These data are then modeled using a global least squares fitting procedure in which the adjustable parameters are represented by the position and orientation of the neodymium magnet. The instrumental resolution of the positioning system can be tuned depending on the strength of the magnetic field generated by the neodymium magnet and the distance between the neodymium magnet and the magnetoresistive sensing array. For a typical installation, the displacement resolution is shown to be circa 10 μm while the rotation resolution is circa 0.1°. The first permanently deployed positioning system was established in June 2016 to monitor the behavior of an N-S trending fault located at the contact between the eastern Alps and the Vienna Basin. The robust design of the positioning system is demonstrated by the fact that no interruptions in the broadcasted data streams have occurred since its installation. It has a range of potential applications in many areas of basic and applied research including geology, geotechnical engineering, and structural health monitoring.

  3. Contactless magneto-permeabilization for intracellular plasmid DNA delivery in-vivo.

    PubMed

    Kardos, Thomas J; Rabussay, Dietmar P

    2012-11-01

    Electroporation, an attractive process for delivering DNA and other molecules into target cells in vivo and in vitro is limited by the necessity of electrodes that need to be in contact with the subject or object to be electroporated. We have used magnetic fields, which do not require material contact with the subject, to temporarily permeabilize cells in guinea pig skin in vivo to enhance uptake and expression of GFP plasmid DNA. The results show for the first time that magnetic fields can trigger a process likely similar to electroporation. In designing the magnetic pulses, our most important criterion was a high rate of change of the magnetic field, based on the principle described by Michael Faraday which is expressed by the formula: E = -dB/dt, (E, electric field, B, magnetic field, t, time). Magnetic fields were generated by a flat electromagnet in a hand-held applicator positioned above the target tissue. The magnetic pulses had a peak magnetic flux density of 4 tesla; 50 pulses were applied in 5 sec. Biphasic magnetic pulses were twice as effective as monophasic pulses and about equally effective as traditional electroporation pulses . Advantages of magnetopermeabilization over electoporation include: No contact between applicator and subject ("contact-less"); no need for invasive, disposable, sterile electrodes ("needle-less"); no pain from needles and reduced overall pain; no known side effects; easier and faster to administer than electroporation; less expensive due to absence of disposables; and, importantly, greater tissue penetration of the magnetic field allowing treatment of anatomical areas inaccessible by electroporation.

  4. Validation of the Sonomat: A Contactless Monitoring System Used for the Diagnosis of Sleep Disordered Breathing

    PubMed Central

    Norman, Mark B.; Middleton, Sally; Erskine, Odette; Middleton, Peter G.; Wheatley, John R.; Sullivan, Colin E.

    2014-01-01

    Study Objective: To evaluate the ability of the Sonomat to diagnose obstructive sleep apnea (OSA). Design: Prospective and randomized. Setting: Sleep laboratory and home. Participants: 62 subjects; 54 with a clinical history of OSA and 8 normal control subjects. Interventions: N/A. Measurements and Results: Simultaneous PSG and Sonomat recordings were made in 62 subjects; 2 were excluded due to a poor nasal flow recording in PSG. There were positive correlations between the two devices for measures of sleep time, respiratory events, and the AHI (all correlations > 0.89). Bland-Altman analysis of the AHI showed positive agreement between devices, particularly at levels around common diagnostic thresholds. The mean difference in AHI values was 1.4 events per hour, and at a diagnostic threshold of 15 events per hour, sensitivity and specificity were 88% and 91%. More than 93% of PSG defined respiratory events were identified by the Sonomat and the absence of respiratory events was correctly identified in 91% of occasions. Gender, obesity, and body position did not influence the accuracy of the Sonomat. PSG snore sensors differed in how much snoring was detected when compared to the Sonomat. Conclusion: These data indicate that the Sonomat was reliable and accurate for the diagnosis of OSA. The provision of audible breath sound/snoring replay permits more accurate quantification of snoring. It requires no patient attachment and can be performed in the home with minimal training. Citation: Norman MB, Middleton S, Erskine O, Middleton PG, Wheatley JR, Sullivan CE. Validation of the Sonomat: a contactless monitoring system used for the diagnosis of sleep disordered breathing. SLEEP 2014;37(9):1477-1487. PMID:25142565

  5. Enhanced contactless dielectrophoresis enrichment and isolation platform via cell-scale microstructures.

    PubMed

    Čemažar, Jaka; Douglas, Temple A; Schmelz, Eva M; Davalos, Rafael V

    2016-01-01

    We designed a new microfluidic device that uses pillars on the same order as the diameter of a cell (20 μm) to isolate and enrich rare cell samples from background. These cell-scale microstructures improve viability, trapping efficiency, and throughput while reducing pearl chaining. The area where cells trap on each pillar is small, such that only one or two cells trap while fluid flow carries away excess cells. We employed contactless dielectrophoresis in which a thin PDMS membrane separates the cell suspension from the electrodes, improving cell viability for off-chip collection and analysis. We compared viability and trapping efficiency of a highly aggressive Mouse Ovarian Surface Epithelial (MOSE) cell line in this 20 μm pillar device to measurements in an earlier device with the same layout but pillars of 100 μm diameter. We found that MOSE cells in the new device with 20 μm pillars had higher viability at 350 VRMS, 30 kHz, and 1.2 ml/h (control 77%, untrapped 71%, trapped 81%) than in the previous generation device (untrapped 47%, trapped 42%). The new device can trap up to 6 times more cells under the same conditions. Our new device can sort cells with a high flow rate of 2.2 ml/h and throughput of a few million cells per hour while maintaining a viable population of cells for off-chip analysis. By using the device to separate subpopulations of tumor cells while maintaining their viability at large sample sizes, this technology can be used in developing personalized treatments that target the most aggressive cancerous cells.

  6. Enhanced contactless dielectrophoresis enrichment and isolation platform via cell-scale microstructures

    PubMed Central

    Čemažar, Jaka; Douglas, Temple A.; Schmelz, Eva M.; Davalos, Rafael V.

    2016-01-01

    We designed a new microfluidic device that uses pillars on the same order as the diameter of a cell (20 μm) to isolate and enrich rare cell samples from background. These cell-scale microstructures improve viability, trapping efficiency, and throughput while reducing pearl chaining. The area where cells trap on each pillar is small, such that only one or two cells trap while fluid flow carries away excess cells. We employed contactless dielectrophoresis in which a thin PDMS membrane separates the cell suspension from the electrodes, improving cell viability for off-chip collection and analysis. We compared viability and trapping efficiency of a highly aggressive Mouse Ovarian Surface Epithelial (MOSE) cell line in this 20 μm pillar device to measurements in an earlier device with the same layout but pillars of 100 μm diameter. We found that MOSE cells in the new device with 20 μm pillars had higher viability at 350 VRMS, 30 kHz, and 1.2 ml/h (control 77%, untrapped 71%, trapped 81%) than in the previous generation device (untrapped 47%, trapped 42%). The new device can trap up to 6 times more cells under the same conditions. Our new device can sort cells with a high flow rate of 2.2 ml/h and throughput of a few million cells per hour while maintaining a viable population of cells for off-chip analysis. By using the device to separate subpopulations of tumor cells while maintaining their viability at large sample sizes, this technology can be used in developing personalized treatments that target the most aggressive cancerous cells. PMID:26858821

  7. Contactless Abdominal Fat Reduction With Selective RF™ Evaluated by Magnetic Resonance Imaging (MRI): Case Study.

    PubMed

    Downie, Jeanine; Kaspar, Miroslav

    2016-04-01

    Noninvasive body shaping methods seem to be an ascending part of the aesthetics market. As a result, the pressure to develop reliable methods for the collection and presentation of their results has also increased. The most used techniques currently include ultrasound measurements of fat thickness in the treated area, caliper measurements, bioimpedance-based scale measurements or circumferential tape measurements. Although these are the most used techniques, almost all of them have some limitations in reproducibility and/or accuracy. This study shows Magnetic Resonance Imaging (MRI) as the new method for the presentation of results in the body shaping industry. Six subjects were treated by a contactless selective radiofrequency device (BTL Vanquish ME, BTL Industries Inc., Boston, MA). The MRI fat thickness was measured at the baseline and at 4-weeks following the treatment. In addition to MRI images and measurements, digital photographs and anthropometric evaluations such as weight, abdominal circumference, and caliper fat thickness measurements were recorded. Abdominal fat thickness measurements from the MRI were performed from the same slices determined by the same tissue artefacts. The MRI fat thickness difference between the baseline measurement and follow up visit showed an average reduction of 5.36 mm as calculated from the data of 5 subjects. One subject dropped out of study due to non-study related issues. The results were statistically significant based on the Student's T-test evaluation. Magnetic resonance imaging abdominal fat thickness measurements seems to be the best method for the evaluation of fat thickness reduction after non-invasive body shaping treatments. In this study, this method shows average fat thickness reduction of 5.36 mm while the weight of the subjects didn't change significantly. A large spot size measuring 1317 cm(2) (204 square inches) covers the abdomen flank to flank. The average thickness of 5.36 mm of the fat layer reduced

  8. Towards Contactless Silent Speech Recognition Based on Detection of Active and Visible Articulators Using IR-UWB Radar

    PubMed Central

    Shin, Young Hoon; Seo, Jiwon

    2016-01-01

    People with hearing or speaking disabilities are deprived of the benefits of conventional speech recognition technology because it is based on acoustic signals. Recent research has focused on silent speech recognition systems that are based on the motions of a speaker’s vocal tract and articulators. Because most silent speech recognition systems use contact sensors that are very inconvenient to users or optical systems that are susceptible to environmental interference, a contactless and robust solution is hence required. Toward this objective, this paper presents a series of signal processing algorithms for a contactless silent speech recognition system using an impulse radio ultra-wide band (IR-UWB) radar. The IR-UWB radar is used to remotely and wirelessly detect motions of the lips and jaw. In order to extract the necessary features of lip and jaw motions from the received radar signals, we propose a feature extraction algorithm. The proposed algorithm noticeably improved speech recognition performance compared to the existing algorithm during our word recognition test with five speakers. We also propose a speech activity detection algorithm to automatically select speech segments from continuous input signals. Thus, speech recognition processing is performed only when speech segments are detected. Our testbed consists of commercial off-the-shelf radar products, and the proposed algorithms are readily applicable without designing specialized radar hardware for silent speech processing. PMID:27801867

  9. Towards Contactless Silent Speech Recognition Based on Detection of Active and Visible Articulators Using IR-UWB Radar.

    PubMed

    Shin, Young Hoon; Seo, Jiwon

    2016-10-29

    People with hearing or speaking disabilities are deprived of the benefits of conventional speech recognition technology because it is based on acoustic signals. Recent research has focused on silent speech recognition systems that are based on the motions of a speaker's vocal tract and articulators. Because most silent speech recognition systems use contact sensors that are very inconvenient to users or optical systems that are susceptible to environmental interference, a contactless and robust solution is hence required. Toward this objective, this paper presents a series of signal processing algorithms for a contactless silent speech recognition system using an impulse radio ultra-wide band (IR-UWB) radar. The IR-UWB radar is used to remotely and wirelessly detect motions of the lips and jaw. In order to extract the necessary features of lip and jaw motions from the received radar signals, we propose a feature extraction algorithm. The proposed algorithm noticeably improved speech recognition performance compared to the existing algorithm during our word recognition test with five speakers. We also propose a speech activity detection algorithm to automatically select speech segments from continuous input signals. Thus, speech recognition processing is performed only when speech segments are detected. Our testbed consists of commercial off-the-shelf radar products, and the proposed algorithms are readily applicable without designing specialized radar hardware for silent speech processing.

  10. A contactless approach for respiratory gating in PET using continuous-wave radar.

    PubMed

    Ersepke, Thomas; Büther, Florian; Heß, Mirco; Schäfers, Klaus P

    2015-08-01

    Respiratory gating is commonly used to reduce motion artifacts in positron emission tomography (PET). Clinically established methods for respiratory gating in PET require contact to the patient or a direct optical line between the sensor and the patient's torso and time consuming preparation. In this work, a contactless method for capturing a respiratory signal during PET is presented based on continuous-wave radar. The proposed method relies on the principle of emitting an electromagnetic wave and detecting the phase shift of the reflected wave, modulated due to the respiratory movement of the patient's torso. A 24 GHz carrier frequency was chosen allowing wave propagation through plastic and clothing with high reflections at the skin surface. A detector module and signal processing algorithms were developed to extract a quantitative respiratory signal. The sensor was validated using a high precision linear table. During volunteer measurements and [(18)F] FDG PET scans, the radar sensor was positioned inside the scanner bore of a PET/computed tomography scanner. As reference, pressure belt (one volunteer), depth camera-based (two volunteers, two patients), and PET data-driven (six patients) signals were acquired simultaneously and the signal correlation was quantified. The developed system demonstrated a high measurement accuracy for movement detection within the submillimeter range. With the proposed method, small displacements of 25 μm could be detected, not considerably influenced by clothing or blankets. From the patient studies, the extracted respiratory radar signals revealed high correlation (Pearson correlation coefficient) to those derived from the external pressure belt and depth camera signals (r = 0.69-0.99) and moderate correlation to those of the internal data-driven signals (r = 0.53-0.70). In some cases, a cardiac signal could be visualized, due to the representation of the mechanical heart motion on the skin. Accurate respiratory signals were

  11. A contactless approach for respiratory gating in PET using continuous-wave radar

    SciTech Connect

    Ersepke, Thomas Büther, Florian; Heß, Mirco; Schäfers, Klaus P.

    2015-08-15

    Purpose: Respiratory gating is commonly used to reduce motion artifacts in positron emission tomography (PET). Clinically established methods for respiratory gating in PET require contact to the patient or a direct optical line between the sensor and the patient’s torso and time consuming preparation. In this work, a contactless method for capturing a respiratory signal during PET is presented based on continuous-wave radar. Methods: The proposed method relies on the principle of emitting an electromagnetic wave and detecting the phase shift of the reflected wave, modulated due to the respiratory movement of the patient’s torso. A 24 GHz carrier frequency was chosen allowing wave propagation through plastic and clothing with high reflections at the skin surface. A detector module and signal processing algorithms were developed to extract a quantitative respiratory signal. The sensor was validated using a high precision linear table. During volunteer measurements and [{sup 18}F] FDG PET scans, the radar sensor was positioned inside the scanner bore of a PET/computed tomography scanner. As reference, pressure belt (one volunteer), depth camera-based (two volunteers, two patients), and PET data-driven (six patients) signals were acquired simultaneously and the signal correlation was quantified. Results: The developed system demonstrated a high measurement accuracy for movement detection within the submillimeter range. With the proposed method, small displacements of 25 μm could be detected, not considerably influenced by clothing or blankets. From the patient studies, the extracted respiratory radar signals revealed high correlation (Pearson correlation coefficient) to those derived from the external pressure belt and depth camera signals (r = 0.69–0.99) and moderate correlation to those of the internal data-driven signals (r = 0.53–0.70). In some cases, a cardiac signal could be visualized, due to the representation of the mechanical heart motion on the skin

  12. Contactless microwave study of shallow traps in thin-film CdSe

    NASA Astrophysics Data System (ADS)

    Grabtchak, Serguei Yu.; Cocivera, Michael

    1994-12-01

    The contactless microwave technique was used to measure light-induced transients in the power absorption by thin films of polycrystalline CdSe. Because the rise time of the detector was 500 ns, the analysis was limited 1 μsec or longer. Measurement of these transients at a number of fixed frequencies across the ``dark'' resonance frequency made reconstruction of the difference signal possible. This signal, which represents the difference between the ``dark'' and ``light'' Lorentz resonance curves, was determined at various times during the decay. Analysis of these signals provided the changes in the real and imaginary parts of the dielectric constant as a function of time. The decays of these parameters were characterized by the sum of two exponential terms: τ1=16.9 μsec and τ2=261.5 μsec for the change in the imaginary part, and τ1=18.5 μsec and τ2=283 μsec for the change in the real part. The close agreement of these values indicates the simultaneous presence of both trapped and free electrons having identical decay times. A mechanism consistent with these results involves rapid equilibration between the free electrons and those in the two shallow traps. Decay from each trap is the rate limiting step, and the time to reach thermodynamic equilibrium must be less than 500 ns. The initial electron densities in the two traps were 2.1×1018 and 1.0×1018 cm-3, and the corresponding concentrations of the free electrons were 3.6×1017 and 1.4×1017 cm-3. For the free electrons, the values for the drift mobility were 2.1 and 1.8 cm2/V s, respectively. Using the harmonic-oscillator model for trapped electrons, the trap energies were 0.096 eV for the fast decay and 0.152 eV for the slower decay. The initial changes in a real part of the dielectric constant were 44.9 and 11.9, respectively. Thus, the photoinduced concentrations of electrons in naturally existing shallow traps are sufficient to effect large changes in the dielectric constant on a short time scale.

  13. Attitudes and perceptions of adults of 60 years and older towards in-home monitoring of the activities of daily living with contactless sensors: an explorative study.

    PubMed

    Claes, Veerle; Devriendt, Els; Tournoy, Jos; Milisen, Koen

    2015-01-01

    Contactless monitoring is increasingly used to enhance qualitative and cost-effective care for older persons. Succesful integration of this technology in older peoples' daily lives, depends on their acceptance of these systems. The primary purpose was to explore attitudes and perceptions of adults of 60 years and older towards contactless monitoring of the activities of daily living. A questionnaire was developed, validated and used in a cross-sectional survey with a convenience sample (n=245). The results were presented using descriptive statistics and bivariate analyses to explore variables associated with willingness to install the technology. Descriptive statistics indicate that adults of 60 years and older find contactless monitoring useful for various purposes (e.g. to remain living at home longer, safely and independently; for timely detection of emergency situations and gradually emerging health problems). They agree to share collected information with professional caregivers and own access to the data is valued. Respondents like to take part in diverse decisions about the monitoring (e.g. about the rooms in which it is installed, the type of sensors used and access of third parties to collected information). However, several concerns were expressed related to the functioning and financing of contactless monitoring. Bivariate analyses show that both socio-demographic factors (e.g. age, receiving professional home care) and attitudes and perceptions towards contactless monitoring (e.g. on its potential usefulness, on the availability of collected information, on the functional requirements and financial costs of the system and on the use of video cameras) can promote or impede acceptance of the technology. This explorative study indicates that older adults are willing to incorporate contactless monitoring in later life or when their health declines. They agree to share collected information with professional caregivers and clearly demand for participation in

  14. In situ measurement of tissue impedance using an inductive coupling interface circuit.

    PubMed

    Chiu, Hung-Wei; Chuang, Jia-min; Lu, Chien-Chi; Lin, Wei-Tso; Lin, Chii-Wann; Lin, Mu-Lien

    2013-06-01

    In this work, a method of an inductive coupling impedance measurement (ICIM) is proposed for measuring the nerve impedance of a dorsal root ganglion (DRG) under PRF stimulation. ICIM provides a contactless interface for measuring the reflected impedance by an impedance analyzer with a low excitation voltage of 7 mV. The paper develops a calibration procedure involving a 50-Ω reference resistor to calibrate the reflected resistance for measuring resistance of the nerve in the test. A de-embedding technique to build the equivalent transformer circuit model for the ICIM circuit is also presented. A batteryless PRF stimulator with ICIM circuit demonstrated good accuracy for the acute measurement of DRG impedance both in situ and in vivo. Besides, an in vivo animal experiment was conducted to show that the effectiveness of pulsed radiofrequency (PRF) stimulation in relieving pain gradually declined as the impedance of the stimulated nerve increased. The experiment also revealed that the excitation voltage for measuring impedance below 25 mV can prevent the excitation of a nonlinear response of DRG.

  15. Towards an improved and more flexible representation of water stress in coupled photosynthesis-stomatal conductance models; implications for simulated land surface fluxes and variables at various spatiotemporal scales

    NASA Astrophysics Data System (ADS)

    Egea, G.; Verhoef, A.; Vidale, P. L.; Black, E.; Van den Hoof, C.

    2012-04-01

    Coupled photosynthesis-stomatal conductance (A-gs) models are commonly used in ecosystem models to represent the exchange rate of CO2 and H2O between vegetation and the atmosphere. The ways these models account for water stress differ greatly among modelling schemes. This study provides insight into the impact of contrasting model configurations of water stress on the simulated leaf-level values of net photosynthesis (A), stomatal conductance (gs), the functional relationship among them and their ratio, the intrinsic water use efficiency (A/gs), as soil dries. A simple, yet versatile, normalized soil moisture dependent function was used to account for the effects of water stress on gs, on mesophyll conductance (gm ) and on the biochemical capacity (Egea et al., 2011). Model output was compared to leaf-level values obtained from the literature. The sensitivity analyses emphasized the necessity to combine both stomatal and non-stomatal limitations of A in coupled A-gs models to accurately capture the observed functional relationships A vs. gs and A/gs vs. gs in response to drought. Accounting for water stress in coupled A-gs models by imposing either stomatal or biochemical limitations of A, as commonly practiced in most ecosystem models, failed to reproduce the observed functional relationship between key leaf gas exchange attributes. A quantitative limitation analysis revealed that the general pattern of C3 photosynthetic response to water stress can be represented in coupled A-gs models by imposing the highest limitation strength to mesophyll conductance, then to stomatal conductance and finally to the biochemical capacity. This more realistic representation of soil water stress on the simulated leaf-level values of A and gs was embedded in the JULES (Joint UK Land Environment Simulator; Best et al., 2011), model and tested for a number of vegetation types, for which driving and flux verification data were available. These simulations provide an insight into the

  16. Capillary action-supported contactless atmospheric pressure ionization for the combined sampling and mass spectrometric analysis of biomolecules.

    PubMed

    Hsieh, Cheng-Huan; Chang, Chia-Hsien; Urban, Pawel L; Chen, Yu-Chie

    2011-04-15

    It is proposed that a short tapered capillary can be utilized as a nanoliter-volume sampling tool and sample emitter for generation of gas-phase ions in front of the mass spectrometer, without the need for using an additional electric power supply, a gas supply, or a syringe pump. A wide range of molecules can be analyzed in pure solutions and complex matrixes (cell extract, urine, and plant tissue) with no or minimum sample preparation. Singly and multiply charged ions can be detected in either positive or negative-ion mode. Because of the nanoliter-volume sampling and low spectral background, the mass detection limit for bradykinin is in the low attomole range. Other advantages include simplicity, disposability, and low cost. The putative mechanism of the ion formation in this capillary-action supported contactless spray emitter is discussed.

  17. Scientific Ground of a New Optical Device for Contactless Measurement of the Small Spatial Displacements of Control Object Surfaces

    NASA Astrophysics Data System (ADS)

    Miroshnichenko, I. P.; Parinov, I. A.

    2017-06-01

    It is proposed the computational-experimental ground of newly developed optical device for contactless measurement of small spatial displacements of control object surfaces based on the use of new methods of laser interferometry. The proposed device allows one to register linear and angular components of the small displacements of control object surfaces during the diagnosis of the condition of structural materials for forced elements of goods under exploring by using acoustic non-destructive testing methods. The described results are the most suitable for application in the process of high-precision measurements of small linear and angular displacements of control object surfaces during experimental research, the evaluation and diagnosis of the state of construction materials for forced elements of goods, the study of fast wave propagation in layered constructions of complex shape, manufactured of anisotropic composite materials, the study of damage processes in modern construction materials in mechanical engineering, shipbuilding, aviation, instrumentation, power engineering, etc.

  18. K-band Doppler radar for contact-less overnight sleep marker assessment: a pilot validation study.

    PubMed

    Vasireddy, Rakesh; Roth, Corinne; Mathis, Johannes; Goette, Josef; Jacomet, Marcel; Vogt, Andreas

    2017-09-11

    An estimated 45 million persons in Europe are annually subjected to sleep-wake disorders. State-of-the-art polysomnography provides sophisticated insights into sleep (patho)physiology. A drawback of the method, however, is the obtrusive setting dependent on a clinical-based sleep laboratory with high operational costs. A contact-less prototype was developed to monitor limb movements and vital signs during sleep. A dual channel K-band Doppler radar transceiver captured limb movements and periodic chest wall motion due to respiration and heart activity. A wavelet transform based multi-resolution analysis (MRA) approach isolated limb movements, respiration, and heart rate from the demodulated signal. A test bench setup characterized the prototype simulating near physiological chest wall motions caused by periodic respiration and heartbeats in humans. Single- and multi-tone test bench simulations showed extremely low relative percentage errors of the prototype for respiratory and heart rate within -2 and 1%. The performance of the prototype was validated in overnight comparative studies, involving two healthy volunteers, with polysomnography as the reference. The prototype has successfully classified limb movements, with a sensitivity and specificity of 88.9 and 76.8% respectively, and has achieved accurate respiratory and heart rate measurement performance with overall absolute errors of 1 breath per minute for respiration and 3 beats per minute for heart rate. This pilot study shows that K-band Doppler radar and wavelet transform MRA seem to be valid for overnight sleep marker assessment. The contact-less approach might offer a promising solution for home-based sleep monitoring and assessment.

  19. Coupled theoretical interpretation and experimental investigation of the anisotropy of the lattice thermal conductivity of Bi{sub 2}Te{sub 3} single crystal

    SciTech Connect

    Jacquot, A.; Bayer, B.; Winkler, M.; Boettner, H.; Jaegle, M.

    2012-09-15

    The Debye model is modified for the calculation of the lattice thermal conductivity and used to gain insight into the anisotropy of Bi{sub 2}Te{sub 3}. In this work, the Debye temperature is not used to estimate the cutoff frequencies of the phonons that carry heat. The cutoff frequencies are defined by setting an upper limit to the energy of acoustic phonons using the complete dispersion relations. The anisotropy of the thermal conductivity is found to be unrelated to the anisotropy of the sound velocities. It is found that the sound velocity is almost isotropic when the longitudinal and two transversal waves are added together. In addition the relaxation time must be a function of the cutoff frequencies and counterbalances the anisotropy arising from the variation of the number of acoustic phonons traveling in various directions. It is concluded that the anisotropy of the thermal conductivity is mostly related to the Grueneisen's constant. - Graphical abstract: Dispersion relations of Bi{sub 2}Te{sub 3} along c-axis. The cutoff frequencies are found to be anisotropic and are defined exactly in this article where the acoustic branch crosses the optical branch. This affects both the number of phonons that carry heat in a given direction and the number of phonons that can scatter them. This is decisive for understanding the lattice thermal conductivity. Highlights: Black-Right-Pointing-Pointer Prediction of the anisotropy of the lattice thermal conductivity. Black-Right-Pointing-Pointer Provide a definition of the cutoff frequencies that makes sense. Black-Right-Pointing-Pointer Reduction of the number of frees parameter in phenomenological model. Black-Right-Pointing-Pointer Prediction that the anisotropy is a function of the scattering mechanism. Black-Right-Pointing-Pointer Means of experimental verification of theory.

  20. Influence of perpendicular magnetic field and polarized current on the dynamics of coupled magnetic vortices in a thin nanocolumnar trilayer conducting structure

    NASA Astrophysics Data System (ADS)

    Ekomasov, A. E.; Stepanov, S. V.; Zvezdin, K. A.; Ekomasov, E. G.

    2017-04-01

    A micromagnetic investigation of the dynamics of two dipole-coupled magnetic vortices in a magnetic tunnel nanocolumn under the action of an external magnetic field directed perpendicularly to the plane of the sample and of a spin-polarized electric current has been carried out. Three regimes of motion of the vortices have been shown to exist that differ in critical values of the current. The dependence of the magneticfield strength that separately switches the polarity of the cores of the vortices depending on the density of the spin-polarized current has been found. The possibility of controlling the frequency of the stationary motion of the vortices and of the fine adjustment of the amplitude of the controlling currents using an external magnetic field has been suggested.

  1. Enhanced Surface-and-Interface Coupling in Pd-Nanoparticle-coated LaAlO3/SrTiO3 Heterostructures: Strong Gas- and Photo-Induced Conductance Modulation

    PubMed Central

    Kim, Haeri; Chan, Ngai Yui; Dai, Ji-yan; Kim, Dong-Wook

    2015-01-01

    Pd nanoparticle (NP) coated LaAlO3/SrTiO3 (LAO/STO) heterointerface exhibits more notable conductance (G) change while varying the ambient gas (N2, H2/N2, and O2) and illuminating with UV light (wavelength: 365 nm) than a sample without the NPs. Simultaneous Kelvin probe force microscopy and transport measurements reveal close relationships between the surface work function (W) and G of the samples. Quantitative analyses suggest that a surface adsorption/desorption-mediated reaction and redox, resulting in a band-alignment modification and charge-transfer, could explain the gas- and photo-induced conductance modulation at the LAO/STO interface. Such surface-and-interface coupling enhanced by catalytic Pd NPs is a unique feature, quite distinct from conventional semiconductor hetero-junctions, which enables the significant conductance tunability at ultrathin oxide heterointerfaces by external stimuli. PMID:25704566

  2. Enhanced surface-and-interface coupling in Pd-nanoparticle-coated LaAlO3/SrTiO3 heterostructures: strong gas- and photo-induced conductance modulation.

    PubMed

    Kim, Haeri; Chan, Ngai Yui; Dai, Ji-yan; Kim, Dong-Wook

    2015-02-23

    Pd nanoparticle (NP) coated LaAlO3/SrTiO3 (LAO/STO) heterointerface exhibits more notable conductance (G) change while varying the ambient gas (N2, H2/N2, and O2) and illuminating with UV light (wavelength: 365 nm) than a sample without the NPs. Simultaneous Kelvin probe force microscopy and transport measurements reveal close relationships between the surface work function (W) and G of the samples. Quantitative analyses suggest that a surface adsorption/desorption-mediated reaction and redox, resulting in a band-alignment modification and charge-transfer, could explain the gas- and photo-induced conductance modulation at the LAO/STO interface. Such surface-and-interface coupling enhanced by catalytic Pd NPs is a unique feature, quite distinct from conventional semiconductor hetero-junctions, which enables the significant conductance tunability at ultrathin oxide heterointerfaces by external stimuli.

  3. [Wolff-Parkinson-White syndrome. Value of transesophageal atrial stimulation coupled with exercise test for the study of anterograde conduction in the accessory pathway].

    PubMed

    Cebron, J P; Le Marec, H; Victor, J; Chevallier, J C; Borgat, C; Godin, J F

    1989-02-01

    In patients with Wolff-Parkinson-White syndrome the anterograde conduction properties of the accessory pathway determine the ventricular rate in case of atrial fibrillation (AF). Anterograde conduction in the accessory pathway was evaluated in 20 patients (mean age 31 years) by means of transoesophageal atrial pacing with increasing frequency (up to 460 per minute), first at rest, then during exercise on an ergometric bicycle and upon immediate recovery. The exploration was completed by a search for the disappearance of pre-excitation during exercise and after an intravenous injection of ajmaline 1 mg/kg. The shortest cycle (SC) of atrial pacing with 1:1 conduction by the accessory pathway regularly decreased by 80 +/- 26 ms (n = 18), i.e. 27 p. 100 of its value at rest. At immediate recovery SC increased by 40 +/- 53 ms (n = 9). Atrial fibrillation was induced at rest and/or during exercise in 12 patients. The shortest interval (SI) between two pre-excited ventricular complexes was 290 +/- 80 ms (n = 8) at rest and 244 +/- 53 ms (n = 8) during exercise. With a substantial group of values (n = 12) there was good correlation between SC and SI both at rest and during exercise. With a smaller group of values (n = 3) SI was clearly greater than SC, suggesting a concealed conduction in the accessory pathway during atrial fibrillation. Disappearance of pre-excitation during exercise was observed in 4 patients, 3 of whom had a short (less than 250 ms) SC and/or SI.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. The mammalian Na+/H+ antiporters NHE-1, NHE-2, and NHE-3 are electroneutral and voltage independent, but can couple to an H+ conductance

    PubMed Central

    1995-01-01

    Na+/H+ exchange in vertebrates is thought to be electroneutral and insensitive to the membrane voltage. This basic concept has been challenged by recent reports of antiport-associated currents in the turtle colon epithelium (Post and Dawson, 1992, 1994). To determine the electrogenicity of mammalian antiporters, we used the whole-cell patch clamp technique combined with microfluorimetric measurements of intracellular pH (pHi). In murine macrophages, which were found by RT- PCR to express the NHE-1 isoform of the antiporter, reverse (intracellular Na(+)-driven) Na+/H+ exchange caused a cytosolic acidification and activated an outward current, whereas forward (extracellular Na(+)-driven) exchange produced a cytosolic alkalinization and reduced a basal outward current. The currents mirrored the changes in pHi, were strictly dependent on the presence of a Na+ gradient and were reversibly blocked by amiloride. However, the currents were seemingly not carried by the Na+/H+ exchanger itself, but were instead due to a shift in the voltage dependence of a preexisting H+ conductance. This was supported by measurements of the reversal potential (Erev) of tail currents, which identified H+ (equivalents) as the charge carrier. During Na+/H+ exchange, Erev changed along with the measured changes in pHi (by 60-69 mV/pH). Moreover, the current and Na+/H+ exchange could be dissociated. Zn2+, which inhibits the H+ conductance, reversibly blocked the currents without altering Na+/H+ exchange. In Chinese hamster ovary (CHO) cells, which lack the H+ conductance, Na+/H+ exchange produced pHi changes that were not accompanied by transmembrane currents. Similar results were obtained in CHO cells transfected with either the NHE-1, NHE-2, or NHE-3 isoforms of the antiporter, indicating that exchange through these isoforms is electroneutral. In all the isoforms tested, the amplitude and time- course of the antiport-induced pHi changes were independent of the holding voltage. We conclude that

  5. Fast contactless vibrating structure characterization using real time field programmable gate array-based digital signal processing: Demonstrations with a passive wireless acoustic delay line probe and vision

    NASA Astrophysics Data System (ADS)

    Goavec-Mérou, G.; Chrétien, N.; Friedt, J.-M.; Sandoz, P.; Martin, G.; Lenczner, M.; Ballandras, S.

    2014-01-01

    Vibrating mechanical structure characterization is demonstrated using contactless techniques best suited for mobile and rotating equipments. Fast measurement rates are achieved using Field Programmable Gate Array (FPGA) devices as real-time digital signal processors. Two kinds of algorithms are implemented on FPGA and experimentally validated in the case of the vibrating tuning fork. A first application concerns in-plane displacement detection by vision with sampling rates above 10 kHz, thus reaching frequency ranges above the audio range. A second demonstration concerns pulsed-RADAR cooperative target phase detection and is applied to radiofrequency acoustic transducers used as passive wireless strain gauges. In this case, the 250 ksamples/s refresh rate achieved is only limited by the acoustic sensor design but not by the detection bandwidth. These realizations illustrate the efficiency, interest, and potentialities of FPGA-based real-time digital signal processing for the contactless interrogation of passive embedded probes with high refresh rates.

  6. Fast contactless vibrating structure characterization using real time field programmable gate array-based digital signal processing: demonstrations with a passive wireless acoustic delay line probe and vision.

    PubMed

    Goavec-Mérou, G; Chrétien, N; Friedt, J-M; Sandoz, P; Martin, G; Lenczner, M; Ballandras, S

    2014-01-01

    Vibrating mechanical structure characterization is demonstrated using contactless techniques best suited for mobile and rotating equipments. Fast measurement rates are achieved using Field Programmable Gate Array (FPGA) devices as real-time digital signal processors. Two kinds of algorithms are implemented on FPGA and experimentally validated in the case of the vibrating tuning fork. A first application concerns in-plane displacement detection by vision with sampling rates above 10 kHz, thus reaching frequency ranges above the audio range. A second demonstration concerns pulsed-RADAR cooperative target phase detection and is applied to radiofrequency acoustic transducers used as passive wireless strain gauges. In this case, the 250 ksamples/s refresh rate achieved is only limited by the acoustic sensor design but not by the detection bandwidth. These realizations illustrate the efficiency, interest, and potentialities of FPGA-based real-time digital signal processing for the contactless interrogation of passive embedded probes with high refresh rates.

  7. IN-SITU Monitoring Of OMVPE Of GaAs And Ga1-xAlxAs (x = 0.17) By Contactless Photoreflectance

    NASA Astrophysics Data System (ADS)

    Shen, Hongen; Hang, Z.; Pollak, Fred H.; Capuder, Kenneth; Norris, Peter E.

    1990-02-01

    We have successfully applied the contactless, non-invasive electromodulation method of photoreflectance as an in-situ sensor of the OMVPE process. The direct gaps of GaAs and Ga1-xAlxAs(x = 0.17) have been measured as a function of temperature up to 690°C, in-situ, under actual OMVPE growth conditions, including a rotating substrate holder (~ 500 rev/min) and flowing gases.

  8. Rigid-flexible coupling high ionic conductivity polymer electrolyte for an enhanced performance of LiMn2O4/graphite battery at elevated temperature.

    PubMed

    Hu, Pu; Duan, Yulong; Hu, Deping; Qin, Bingsheng; Zhang, Jianjun; Wang, Qingfu; Liu, Zhihong; Cui, Guanglei; Chen, Liquan

    2015-03-04

    LiMn2O4-based batteries exhibit severe capacity fading during cycling or storage in LiPF6-based liquid electrolytes, especially at elevated temperatures. Herein, a novel rigid-flexible gel polymer electrolyte is introduced to enhance the cyclability of LiMn2O4/graphite battery at elevated temperature. The polymer electrolyte consists of a robust natural cellulose skeletal incorporated with soft segment poly(ethyl α-cyanoacrylate). The introduction of the cellulose effectively overcomes the drawback of poor mechanical integrity of the gel polymer electrolyte. Density functional theory (DFT) calculation demonstrates that the poly(ethyl α-cyanoacrylate) matrices effectively dissociate the lithium salt to facilitate ionic transport and thus has a higher ionic conductivity at room temperature. Ionic conductivity of the gel polymer electrolyte is 3.3 × 10(-3) S cm(-1) at room temperature. The gel polymer electrolyte remarkably improves the cycling performance of LiMn2O4-based batteries, especially at elevated temperatures. The capacity retention after the 100th cycle is 82% at 55 °C, which is much higher than that of liquid electrolyte (1 M LiPF6 in carbonate solvents). The polymer electrolyte can significantly suppress the dissolution of Mn(2+) from surface of LiMn2O4 because of strong interaction energy of Mn(2+) with PECA, which was investigated by DFT calculation.

  9. Cellulose-coupled graphene/polypyrrole composite electrodes containing conducting networks built by carbon fibers as wearable supercapacitors with excellent foldability and tailorability

    NASA Astrophysics Data System (ADS)

    Lyu, Shaoyi; Chang, Huanjun; Fu, Feng; Hu, La; Huang, Jingda; Wang, Siqun

    2016-09-01

    A paper-based wearable supercapacitor with excellent foldability and tailorability is fabricated from a chopped carbon fiber (CCF)-reinforced cellulose paper electrode material by coating with reduced graphene oxide (RGO) and polypyrrole (PPy) via in situ polymerization. The CCFs not only form an interpenetrating conducting network that acts as highly conductive electron transfer highways for the RGO/PPy layer in the paper electrode, but also endow the resulting electrode with an excellent areal capacitance of 363 mF cm-2 and a volumetric energy density of 0.28 mW h cm-3. Further, the CCFs give the electrode remarkable mechanical robustness, guaranteeing foldability and tailorability, with only slight loss of capacitance after repeated folding 600 times. Even after being subjected to severe cut-in fracture, the capacitance retention is up to 84%, indicating outstanding damage tolerance. The present study reveals a promising candidate for flexible wearable energy storage devices that are required to function in harsh environments.

  10. Single-scan measurement of conductance of a quartz crystal microbalance array coupled with resonant markers for biosensing in liquid phase

    SciTech Connect

    Hsiao, Hsien-Yi; Chen, Richie L. C.; Cheng, Tzong-Jih

    2009-04-15

    This work presents a method for sensing the viscoelastic property of liquid/solid interface using a quartz crystal microbalance (QCM) array. Each sensor in a QCM array has a unique resonant frequency and can be identified by a single-scan measurement of admittance (or impedance). The resonant frequency encoding at each sensor in an array was realized by connecting a capacitor with a known capacitance, called a resonant marker, to the sensor in series. Changes in the resonant frequency of all sensors in an array can be determined using an impedance analyzer and a program that determines the frequencies at which the conductance is at a local maximum. The sensing method allows every sensor output (resonant frequency) to be obtained without the use of time-consuming multiplexed hardware and software. Adsorptions of biomolecules by multiple sensor are monitored in the liquid phase to demonstrate the feasibility of frequency encoding using resonant markers and the single-scan measurement of conductance of a QCM array.

  11. Investigation of ionic conductivity and long-term stability of a LiI and KI coupled diphenylamine quasi-solid-state dye-sensitized solar cell.

    PubMed

    Agarwala, S; Peh, C K N; Ho, G W

    2011-07-01

    In this work, enhancement of ionic conductivity and long-term stability through the addition of diphenylamine (DPA) in poly(ethylene oxide) (PEO) is demonstrated. Potassium iodide (KI) is adopted as the crystal growth inhibitor, and DPA is used as a charge transport enhancer in the electrolyte. The modified electrolyte is used with titanium dioxide (TiO2) nanoparticles, which is systematically tuned to obtain high surface area. The dye-sensitized solar cell (DSSC) showed a photocurrent of 14 mAcm2 with a total conversion efficiency of 5.8% under one sun irradiation. DPA enhances the interaction of the TiO2 nanoparticle film and the I-/I3- electrolyte leading to high ionic conductivity (3.5 × 10-3 Scm-1), without compromising on the electrochemical and mechanical stability. Electrochemical impedance spectroscopy (EIS) studies show that electron transport and electron lifetime are enhanced in the DPA added electrolyte due to reduced sublimation of iodine. The most promising feature of the electrolyte is increased device stability with 89% of the overall efficiency preserved even after 40 days.

  12. A nickel-titanium shape memory alloy plate for contactless inverse dynamization after internal fixation in a sheep tibia fracture model: A pilot study.

    PubMed

    Decker, Sebastian; Krämer, Manuel; Marten, Anna-Katharina; Pfeifer, Ronny; Wesling, Volker; Neunaber, Claudia; Hurschler, Christof; Krettek, Christian; Müller, Christian W

    2015-01-01

    Inverse dynamization has recently been proposed for the treatment of tibia non-unions. Nickel-titanium (NiTi) shape memory alloys (SMAs) may provide an opportunity for contactless non-invasive alteration of the stiffness of an implant after surgery. The aim of this pilot study was to analyze the feasibility of the one way shape memory effect in a large animal as well as the feasibility of our ovine large animal fracture model. A tibia osteotomy was performed in three sheep, followed by NiTi plate osteosynthesis in two cases and standard locking compression plate (LCP) osteosynthesis in one sheep. Contactless induction heating was performed after 3 weeks in order to alter the stiffness of the NiTi plates. Euthanasia was followed by biomechanical analysis after 8 weeks. Successful change of configuration through contactless induction heating was shown in both SMA plates by image intensifier control. Although large differences in bending and torsional stiffness were observed between the operated and contralateral tibia, the sheep ambulated almost normally at six weeks post-operative. We were able to trigger the one way shape memory effect which non-invasively altered the stiffness of the plate osteosynthesis.

  13. Functional coupling between large-conductance potassium channels and Cav3.2 voltage-dependent calcium channels participates in prostate cancer cell growth

    PubMed Central

    Gackière, Florian; Warnier, Marine; Katsogiannou, Maria; Derouiche, Sandra; Delcourt, Philippe; Dewailly, Etienne; Slomianny, Christian; Humez, Sandrine; Prevarskaya, Natalia; Roudbaraki, Morad; Mariot, Pascal

    2013-01-01

    Summary It is strongly suspected that potassium (K+) channels are involved in various aspects of prostate cancer development, such as cell growth. However, the molecular nature of those K+ channels implicated in prostate cancer cell proliferation and the mechanisms through which they control proliferation are still unknown. This study uses pharmacological, biophysical and molecular approaches to show that the main voltage-dependent K+ current in prostate cancer LNCaP cells is carried by large-conductance BK channels. Indeed, most of the voltage-dependent current was inhibited by inhibitors of BK channels (paxillin and iberiotoxin) and by siRNA targeting BK channels. In addition, we reveal that BK channels constitute the main K+ channel family involved in setting the resting membrane potential in LNCaP cells at around −40 mV. This consequently promotes a constitutive calcium entry through T-type Cav3.2 calcium channels. We demonstrate, using single-channel recording, confocal imaging and co-immunoprecipitation approaches, that both channels form macromolecular complexes. Finally, using flow cytometry cell cycle measurements, cell survival assays and Ki67 immunofluorescent staining, we show that both BK and Cav3.2 channels participate in the proliferation of prostate cancer cells. PMID:24143281

  14. Power and signal transmission protocol for a contactless subdural spinal cord stimulation device.

    PubMed

    Song, Suk-Heung; Gillies, George T; Howard, Matthew A; Kuhnley, Brian; Utz, Marcel

    2013-02-01

    Wireless signal transmission will play a critical role in developing reliable subdural spinal cord stimulation systems. We have developed an approach to inductively coupling signals across the epidural spacing between the pial and epidural surfaces. The major design constraints include tolerance of coil misalignments from spinal cord geometries in addition to reasonable power efficiencies within the expected range of movement. The design of the primary side as a driving circuit is simplified by several turns of commercial magnetic wire, whereas the implanted secondary side is implemented in a micro-planar spiral coil tuned to a resonant frequency of 1.6 MHz. We present the results of wireless inductive coupling experiments that demonstrate the ability to transmit and receive a frequency modulated 1.6 MHz carrier signal between primary and secondary coil antennae scaled to 10 mm. Power delivery is in the range of 400 mW at a link efficiency of 32 % for strong coupling (coil separations of 0.5 mm ) and in the range of 70 mW at 4 % efficiency for weak coupling (coil separations of 10 mm).

  15. Decreases in Stomatal Conductance of Soybean under Open-Air Elevation of [CO2] Are Closely Coupled with Decreases in Ecosystem Evapotranspiration12[W][OA

    PubMed Central

    Bernacchi, Carl J.; Kimball, Bruce A.; Quarles, Devin R.; Long, Stephen P.; Ort, Donald R.

    2007-01-01

    Stomatal responses to atmospheric change have been well documented through a range of laboratory- and field-based experiments. Increases in atmospheric concentration of CO2 ([CO2]) have been shown to decrease stomatal conductance (gs) for a wide range of species under numerous conditions. Less well understood, however, is the extent to which leaf-level responses translate to changes in ecosystem evapotranspiration (ET). Since many changes at the soil, plant, and canopy microclimate levels may feed back on ET, it is not certain that a decrease in gs will decrease ET in rain-fed crops. To examine the scaling of the effect of elevated [CO2] on gs at the leaf to ecosystem ET, soybean (Glycine max) was grown in field conditions under control (approximately 375 μmol CO2 mol−1 air) and elevated [CO2] (approximately 550 μmol mol−1) using free air CO2 enrichment. ET was determined from the time of canopy closure to crop senescence using a residual energy balance approach over four growing seasons. Elevated [CO2] caused ET to decrease between 9% and 16% depending on year and despite large increases in photosynthesis and seed yield. Ecosystem ET was linked with gs of the upper canopy leaves when averaged across the growing seasons, such that a 10% decrease in gs results in a 8.6% decrease in ET; this relationship was not altered by growth at elevated [CO2]. The findings are consistent with model and historical analyses that suggest that, despite system feedbacks, decreased gs of upper canopy leaves at elevated [CO2] results in decreased transfer of water vapor to the atmosphere. PMID:17114275

  16. Design and realization of a contact-less interaction system based on infrared reflection photoelectric detection array

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Lei, Bing; Feng, Ying

    2015-10-01

    Due to the good performance of high sensitivity, quick response and low cost, infrared reflection detection technology is widely used in various fields. In this work, we present a novel contact-less interaction system which is based on infrared reflection detection technology. The system is mainly composed of a Micro Controller Unit (MCU), upper computer and photoelectric detection module. The MCU is utilized to control the photoelectric detection module and to make sure that the sensing unit is lighted one by one in a given order. When the interactive object appears upon the infrared reflection photoelectric detection array, its position information will be ensured and sent to the upper computer through MCU. In this system, every sensing unit is lighted for 1ms, and the detection array includes 8×8 units. It means that the photoelectric detection array will scan 15.6 times per-second. The experimental research results indicate that the factors affecting the detection range including the working current of transmitting diode, modulation frequency, and the reflectivity of the interactive object. When the working current is 10mA, and the modulation frequency is 80 KHz, the system has a detection range of 20 cm. Moreover, efficient modulation and demodulation of optical signal is quite necessary to remove the influence of surrounding light.

  17. Direct and contactless electrical control of temperature of paper and textile foldable substrates using electrospun metallic-web transparent electrodes

    PubMed Central

    Busuioc, Cristina; Evanghelidis, Alexandru; Galatanu, Andrei; Enculescu, Ionut

    2016-01-01

    Multiple and complex functionalities are a demand nowadays for almost all materials, including common day-to-day materials such as paper, textiles, wood, etc. In the present report, the surface temperature control of different types of materials, including paper and textiles, was demonstrated by Joule heating of metallic-web transparent electrodes both by direct current and by RF induced eddy currents. Polymeric submicronic fiber webs were prepared by electrospinning, and metal sputtering was subsequently performed to transform them into flexible transparent electrodes. These electrodes were thermally attached to different substrates, including paper, textiles and glass. Using thermochromic inks, we demonstrated a high degree of control of the substrates’ surface temperature by means of the Joule effect. Metallic fiber webs appear to be excellently suited for use as transparent electrodes for controlling the surface temperature of common materials, their highly flexible nature being a major advantage when dealing with rough, bendable substrates. This kind of result could not be achieved on bendable substrates with rough surfaces such as paper or textiles while employing classical transparent electrodes i.e. metal oxides. Moreover, contactless heating with induced currents is a premiere for transparent electrodes and opens up a score of new application fields. PMID:27721382

  18. Capillary electrophoresis with contactless conductometric detection for rapid screening of formate in blood serum after methanol intoxication.

    PubMed

    Kubáň, Petr; Foret, František; Bocek, Robert

    2013-03-15

    A new method for rapid, direct determination of formate in blood serum samples by capillary electrophoresis with contactless conductometric detection is presented. A selective separation of formate was achieved in approximately 1 min using an electrolyte system comprising 10 mM L-histidine, 15 mM glutamic acid and 30 μM cetyltrimethylammonium bromide at pH 4.56. The only sample preparation was dilution (1:100) with deionized water. The limit of detection and limit of quantitation was 2.2 μM and 7.3 μM, respectively, which corresponds to 0.22 mM and 0.73 mM in undiluted blood serum. The method provides a simple and rapid diagnostic test in suspected methanol intoxication cases. The method has been successfully tested on determination of formate in blood of a patient admitted to the hospital under acute methanol intoxication. The peak concentration of formate detected in the patient blood serum was 12.4mM, which is 10- to 100-fold higher than the normal values in healthy population. The developed method presents the fastest test currently available to detect formate in blood samples.

  19. Separation of oxalate, formate and glycolate in human body fluid samples by capillary electrophoresis with contactless conductometric detection.

    PubMed

    Kubáň, Petr; Ďurč, Pavol; Bittová, Miroslava; Foret, František

    2014-01-17

    A new method for rapid determination of toxic metabolites after methanol and ethylene glycol intoxication - oxalate, formate and glycolate in various body fluid samples (blood serum, saliva, urine, exhaled breath condensate) by capillary electrophoresis with contactless conductometric detection was developed. A selective separation of the three target analytes from other constituents present in the analyzed biological matrices was achieved in less than 6min in a fused silica capillary of 25μm I.D. using an electrolyte comprising 50mM l-histidine and 50mM 2-(N-morpholino)ethanesulfonic acid at pH 6.1. The only sample preparation was dilution with deionized water. The limits of detection were 0.4, 0.6 and 1.3μM and limits of quantitation 1.3, 1.9 and 4.2μM for oxalate, formate and glycolate, respectively. The method provides a simple and rapid diagnostic test in suspected intoxication and is able to distinguish the ingested liquid, based on its metabolite trace. The method presents a fast screening tool that can be applicable in clinical practice.

  20. Contactless transport of matter in the first five resonance modes of a line-focused acoustic manipulator.

    PubMed

    Foresti, Daniele; Nabavi, Majid; Poulikakos, Dimos

    2012-02-01

    The first five resonance modes for transport of matter in a line-focused acoustic levitation system are investigated. Contactless transport was achieved by varying the height between the radiating plate and the reflector. Transport and levitation of droplets in particular involve two limits of the acoustic forces. The lower limit corresponds to the minimum force required to overcome the gravitational force. The upper limit corresponds to the maximum acoustic pressure beyond which atomization of the droplet occurs. As the droplet size increases, the lower limit increases and the upper limit decreases. Therefore to have large droplets levitated, relatively flat radiation pressure amplitude during the translation is needed. In this study, using a finite element model, the Gor'kov potential was calculated for different heights between the reflector and the radiating plate. The application of the Gor'kov potential was extended to study the range of droplet sizes for which the droplets can be levitated and transported without atomization. It was found that the third resonant mode (H(3)-mode) represents the best compromise between high levitation force and smooth pattern transition, and water droplets of millimeter radius can be levitated and transported. The H(3)-mode also allows for three translation lines in parallel. © 2012 Acoustical Society of America

  1. Contactless Measurement of Magnetic Nanoparticles on Lateral Flow Strips Using Tunneling Magnetoresistance (TMR) Sensors in Differential Configuration.

    PubMed

    Lei, Huaming; Wang, Kan; Ji, Xiaojun; Cui, Daxiang

    2016-12-14

    Magnetic nanoparticles (MNPs) are commonly used in biomedical detection due to their capability to bind with some specific antibodies. Quantification of biological entities could be realized by measuring the magnetic response of MNPs after the binding process. This paper presents a contactless scanning prototype based on tunneling magnetoresistance (TMR) sensors for quantification of MNPs present in lateral flow strips (LFSs). The sensing unit of the prototype composes of two active TMR elements, which are parallel and closely arranged to form a differential sensing configuration in a perpendicular magnetic field. Geometrical parameters of the configuration are optimized according to theoretical analysis of the stray magnetic field produced by the test line (T-line) while strips being scanned. A brief description of our prototype and the sample preparation is presented. Experimental results show that the prototype exhibits the performance of high sensitivity and strong anti-interference ability. Meanwhile, the detection speed has been improved compared with existing similar techniques. The proposed prototype demonstrates a good sensitivity for detecting samples containing human chorionic gonadotropin (hCG) at a concentration of 25 mIU/mL. The T-line produced by the sample with low concentration is almost beyond the visual limit and produces a maximum stray magnetic field some 0.247 mOe at the sensor in the x direction.

  2. Direct and contactless electrical control of temperature of paper and textile foldable substrates using electrospun metallic-web transparent electrodes

    NASA Astrophysics Data System (ADS)

    Busuioc, Cristina; Evanghelidis, Alexandru; Galatanu, Andrei; Enculescu, Ionut

    2016-10-01

    Multiple and complex functionalities are a demand nowadays for almost all materials, including common day-to-day materials such as paper, textiles, wood, etc. In the present report, the surface temperature control of different types of materials, including paper and textiles, was demonstrated by Joule heating of metallic-web transparent electrodes both by direct current and by RF induced eddy currents. Polymeric submicronic fiber webs were prepared by electrospinning, and metal sputtering was subsequently performed to transform them into flexible transparent electrodes. These electrodes were thermally attached to different substrates, including paper, textiles and glass. Using thermochromic inks, we demonstrated a high degree of control of the substrates’ surface temperature by means of the Joule effect. Metallic fiber webs appear to be excellently suited for use as transparent electrodes for controlling the surface temperature of common materials, their highly flexible nature being a major advantage when dealing with rough, bendable substrates. This kind of result could not be achieved on bendable substrates with rough surfaces such as paper or textiles while employing classical transparent electrodes i.e. metal oxides. Moreover, contactless heating with induced currents is a premiere for transparent electrodes and opens up a score of new application fields.

  3. Direct and contactless electrical control of temperature of paper and textile foldable substrates using electrospun metallic-web transparent electrodes.

    PubMed

    Busuioc, Cristina; Evanghelidis, Alexandru; Galatanu, Andrei; Enculescu, Ionut

    2016-10-10

    Multiple and complex functionalities are a demand nowadays for almost all materials, including common day-to-day materials such as paper, textiles, wood, etc. In the present report, the surface temperature control of different types of materials, including paper and textiles, was demonstrated by Joule heating of metallic-web transparent electrodes both by direct current and by RF induced eddy currents. Polymeric submicronic fiber webs were prepared by electrospinning, and metal sputtering was subsequently performed to transform them into flexible transparent electrodes. These electrodes were thermally attached to different substrates, including paper, textiles and glass. Using thermochromic inks, we demonstrated a high degree of control of the substrates' surface temperature by means of the Joule effect. Metallic fiber webs appear to be excellently suited for use as transparent electrodes for controlling the surface temperature of common materials, their highly flexible nature being a major advantage when dealing with rough, bendable substrates. This kind of result could not be achieved on bendable substrates with rough surfaces such as paper or textiles while employing classical transparent electrodes i.e. metal oxides. Moreover, contactless heating with induced currents is a premiere for transparent electrodes and opens up a score of new application fields.

  4. Contactless Measurement of Magnetic Nanoparticles on Lateral Flow Strips Using Tunneling Magnetoresistance (TMR) Sensors in Differential Configuration

    PubMed Central

    Lei, Huaming; Wang, Kan; Ji, Xiaojun; Cui, Daxiang

    2016-01-01

    Magnetic nanoparticles (MNPs) are commonly used in biomedical detection due to their capability to bind with some specific antibodies. Quantification of biological entities could be realized by measuring the magnetic response of MNPs after the binding process. This paper presents a contactless scanning prototype based on tunneling magnetoresistance (TMR) sensors for quantification of MNPs present in lateral flow strips (LFSs). The sensing unit of the prototype composes of two active TMR elements, which are parallel and closely arranged to form a differential sensing configuration in a perpendicular magnetic field. Geometrical parameters of the configuration are optimized according to theoretical analysis of the stray magnetic field produced by the test line (T-line) while strips being scanned. A brief description of our prototype and the sample preparation is presented. Experimental results show that the prototype exhibits the performance of high sensitivity and strong anti-interference ability. Meanwhile, the detection speed has been improved compared with existing similar techniques. The proposed prototype demonstrates a good sensitivity for detecting samples containing human chorionic gonadotropin (hCG) at a concentration of 25 mIU/mL. The T-line produced by the sample with low concentration is almost beyond the visual limit and produces a maximum stray magnetic field some 0.247 mOe at the sensor in the x direction. PMID:27983659

  5. Contactless measurements of charge traps and carrier lifetimes in detector-grade cadmium zinc telluride and mercuric iodide

    NASA Astrophysics Data System (ADS)

    Tepper, Gary C.; Kessick, Royal; James, Ralph B.; Van den Berg, Lodewijk

    2000-11-01

    An understanding of compensation and trapping in Cd1-xZnxTe and HgI2 is necessary in order to improve the size and spectroscopic performance of radiation detectors fabricated from these materials. Although several electron and hole traps have been identified, very little is currently understood about the effect of specific carrier traps on the mean free path of the charge carriers. Characterization techniques such as Thermally Stimulated Current (TSC) or Thermoelectric Emission Spectroscopy (TEES) have been used for trap identification, while time-of-flight techniques have been employed to determine carrier mobility and lifetime but it has proven difficult to correlate the results of these independent measurements. Furthermore, these characterization methods are complicated by the need to make electrical contacts to the material. Here we report on contactless, thermally stimulated lifetime measurements performed on detector-grade Cd1- xZnxTe (x approximately 0.1) and HgI2 crystals using a microwave cavity perturbation method. The microwave technique is complimentary to contact-based methods and provides both trap identification and lifetime determination in a single measurement. The results provide evidence of lifetime-limiting deep traps in these materials. The trap activation energies and the minimum detrapping times are estimated and the results are compared to previous TSC and TEES investigations.

  6. Modeling of the Near Field Coupling Between an External Loop and an Implantable Spiral Chip Antennas in Biosensor Systems

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Miranda, Felix A.

    2006-01-01

    In this paper, the near field coupling between an external hand-held loop antenna and an implantable miniature (1x1 mm) printed square spiral chip antenna used in bio-MEMS sensors for contact-less powering and RF telemetry is investigated. The loop and the spiral are inductively coupled and effectively form a transformer. The numerical results include the quasi-stationary magnetic field pattern of the implanted antenna, near zone wave impedance as a function of the radial distance and the values of the lumped elements in the equivalent circuit model for the transformer.

  7. Indicators: Conductivity

    EPA Pesticide Factsheets

    Conductivity is a measure of the ability of water to pass an electrical current. Because dissolved salts and other inorganic chemicals conduct electrical current, conductivity increases as salinity increases.

  8. On-line capillary isotachophoresis-capillary zone electrophoresis analysis of bromate in drinking waters in an automated analyzer with coupled columns and photometric detection.

    PubMed

    Marák, Jozef; Staňová, Andrea; Vaváková, Veronika; Hrenáková, Martina; Kaniansky, Dušan

    2012-12-07

    A new, sensitive, and robust analytical method based on capillary zone electrophoresis with on-line capillary isotachophoresis sample pretreatment (ITP-CZE) using a column-coupling (CC) arrangement of automated capillary electrophoretic analyzer was developed for determination of bromate in different type of drinking water samples. Both columns were provided with contact-less conductivity detectors and in CZE step UV detection at 200 nm wavelength was used. Electroosmotic flow of the buffer solutions was suppressed with the addition of 0.1% or 0.05% (m/v) methylhydroxyethylcellulose into the leading and terminating electrolyte, respectively. Hydrodynamic and electroosmotic flows of the buffer solutions were successfully suppressed and therefore, only the electrophoretic transport of ions was significant. Limit of detection for bromate approaching 0.6 μg/L was achieved. Good repeatabilities of migration time (RSD less than 0.3%) and peak area (RSD less than 4.0%) at concentration level 1 μg/L were obtained. Robustness of proposed ITP-CZE method and validation parameters were evaluated. Developed automated ITP-CZE method was applied to the determination of bromate in drinking water samples with different content of inorganic macroconstituents without the need of further sample preparation. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Contactless Mobility, Carrier Density, and Sheet Resistance Measurements on Si, GaN, and AlGaN/GaN High Electron Mobility Transistor (HEMT) Wafers

    DTIC Science & Technology

    2015-02-01

    Si, GaN , and AlGaN/ GaN High Electron Mobility Transistor (HEMT) Wafers by Randy P Tompkins and Danh Nguyen Approved for...7209 ● FEB 2015 US Army Research Laboratory Contactless Mobility, Carrier Density, and Sheet Resistance Measurements on Si, GaN , and AlGaN/ GaN ...Resistance Measurements on Si, GaN , and AlGaN/ GaN High Electron Mobility Transistor (HEMT) Wafers 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  10. Automatic sampling and analysis of organics and biomolecules by capillary action-supported contactless atmospheric pressure ionization mass spectrometry.

    PubMed

    Hsieh, Cheng-Huan; Meher, Anil Kumar; Chen, Yu-Chie

    2013-01-01

    Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (∼1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated.

  11. Contactless magnetocardiographic mapping in anesthetized Wistar rats: evidence of age-related changes of cardiac electrical activity.

    PubMed

    Brisinda, Donatella; Caristo, Maria Emiliana; Fenici, Riccardo

    2006-07-01

    Magnetocardiography (MCG) is the recording of the magnetic field (MF) generated by cardiac electrophysiological activity. Because it is a contactless method, MCG is ideal for noninvasive cardiac mapping of small experimental animals. The aim of this study was to assess age-related changes of cardiac intervals and ventricular repolarization (VR) maps in intact rats by means of MCG mapping. Twenty-four adult Wistar rats (12 male and 12 female) were studied, under anesthesia, with the same unshielded 36-channel MCG instrumentation used for clinical recordings. Two sets of measurements were obtained from each animal: 1) at 5 mo of age (297.5 +/- 21 g body wt) and 2) at 14 mo of age (516.8 +/- 180 g body wt). RR and PR intervals, QRS segment, and QTpeak, QTend, JTpeak, JTend, and Tpeak-end were measured from MCG waveforms. MCG imaging was automatically obtained as MF maps and as inverse localization of cardiac sources with equivalent current dipole and effective magnetic dipole models. After 300 s of continuous recording were averaged, the signal-to-noise ratio was adequate for study of atrial and ventricular MF maps and for three-dimensional localization of the underlying cardiac sources. Clear-cut age-related differences in VR duration were demonstrated by significantly longer QTend, JTend, and Tpeak-end in older Wistar rats. Reproducible multisite noninvasive cardiac mapping of anesthetized rats is simpler with MCG methodology than with ECG recording. In addition, MCG mapping provides new information based on quantitative analysis of MF and equivalent sources. In this study, statistically significant age-dependent variations in VR intervals were found.

  12. Automatic Sampling and Analysis of Organics and Biomolecules by Capillary Action-Supported Contactless Atmospheric Pressure Ionization Mass Spectrometry

    PubMed Central

    Hsieh, Cheng-Huan; Meher, Anil Kumar; Chen, Yu-Chie

    2013-01-01

    Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (∼1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated. PMID:23762484

  13. In-line coupling of microextractions across polymer inclusion membranes to capillary zone electrophoresis for rapid determination of formate in blood samples.

    PubMed

    Pantůčková, Pavla; Kubáň, Pavel; Boček, Petr

    2015-08-05

    Polymer inclusion membranes (PIMs) have several important features, i.e., PIMs are dry and non-porous membranes, which can be prepared ahead of use and stored without noticeable deterioration in extraction performance. In this contribution, in-line coupling of microextractions across PIMs to a separation method for clinical purposes was demonstrated for the first time. Formate (the major metabolite in methanol poisoning) was determined in undiluted human serum and whole blood by capillary zone electrophoresis (CZE) with simultaneous capacitively coupled contactless conductivity detection (C(4)D) and UV-Vis detection. A purpose-made microextraction device with PIM was coupled to a commercial CZE instrument in order to ensure complete automation of the entire analytical procedure, i.e., of formate extraction, injection, CZE separation and quantification. PIMs for formate extractions consisted of 60% (w/w) cellulose triacetate as base polymer and 40% (w/w) Aliquat™ 336 as anion carrier. The method was characterized by good repeatability of peak areas (≤7.0%) and migration times (≤0.8%) and by good linearity of calibration curves (r(2) = 0.993-0.999). Limits of detection in various matrices ranged from 15 to 54 μM for C(4)D and from 200 to 635 μM for UV-Vis detection and were sufficiently low to clearly distinguish between endogenous and toxic levels of formate in healthy and methanol intoxicated individuals. In addition, PIMs proved that they may act as phase interfaces with excellent long-term stability since once prepared, they retained their extractions properties for, at least, two months of storage.

  14. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Allen, Philip B.

    1979-01-01

    Examines Drude's classical (1900) theory of electrical conduction, details the objections to and successes of the 1900 theory, and investigates the Quantum (1928) theory of conduction, reviewing its successes and limitations. (BT)

  15. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Allen, Philip B.

    1979-01-01

    Examines Drude's classical (1900) theory of electrical conduction, details the objections to and successes of the 1900 theory, and investigates the Quantum (1928) theory of conduction, reviewing its successes and limitations. (BT)

  16. Contactless experiments on individual DNA molecules show no evidence for molecular wire behavior

    PubMed Central

    Gómez-Navarro, C.; Moreno-Herrero, F.; de Pablo, P. J.; Colchero, J.; Gómez-Herrero, J.; Baró, A. M.

    2002-01-01

    A fundamental requirement for a molecule to be considered a molecular wire (MW) is the ability to transport electrical charge with a reasonably low resistance. We have carried out two experiments that measure first, the charge transfer from an electrode to the molecule, and second, the dielectric response of the MW. The latter experiment requires no contacts to either end of the molecule. From our experiments we conclude that adsorbed individual DNA molecules have a resistivity similar to mica, glass, and silicon oxide substrates. Therefore adsorbed DNA is not a conductor, and it should not be considered as a viable candidate for MW applications. Parallel studies on other nanowires, including single-walled carbon nanotubes, showed conductivity as expected. PMID:12070346

  17. Machine-assisted verification of latent fingerprints: first results for nondestructive contact-less optical acquisition techniques with a CWL sensor

    NASA Astrophysics Data System (ADS)

    Hildebrandt, Mario; Kiltz, Stefan; Krapyvskyy, Dmytro; Dittmann, Jana; Vielhauer, Claus; Leich, Marcus

    2011-11-01

    A machine-assisted analysis of traces from crime scenes might be possible with the advent of new high-resolution non-destructive contact-less acquisition techniques for latent fingerprints. This requires reliable techniques for the automatic extraction of fingerprint features from latent and exemplar fingerprints for matching purposes using pattern recognition approaches. Therefore, we evaluate the NIST Biometric Image Software for the feature extraction and verification of contact-lessly acquired latent fingerprints to determine potential error rates. Our exemplary test setup includes 30 latent fingerprints from 5 people in two test sets that are acquired from different surfaces using a chromatic white light sensor. The first test set includes 20 fingerprints on two different surfaces. It is used to determine the feature extraction performance. The second test set includes one latent fingerprint on 10 different surfaces and an exemplar fingerprint to determine the verification performance. This utilized sensing technique does not require a physical or chemical visibility enhancement of the fingerprint residue, thus the original trace remains unaltered for further investigations. No particular feature extraction and verification techniques have been applied to such data, yet. Hence, we see the need for appropriate algorithms that are suitable to support forensic investigations.

  18. Non-aqueous electrolytes for isotachophoresis of weak bases and its application to the comprehensive preconcentration of the 20 proteinogenic amino acids in column-coupling ITP/CE-MS.

    PubMed

    Kler, Pablo A; Huhn, Carolin

    2014-11-01

    Isotachophoresis (ITP) has long been used alone but also as a preconcentration technique for capillary electrophoresis (CE). Unfortunately, up to now, its application is restricted to relatively strong acids and bases as either the degree of (de)protonation is too low or the water dissociation is too high, evoking zone electrophoresis. With the comprehensive ITP analysis of all 20 proteinogenic amino acids as model analytes, we, here, show that non-aqueous ITP using dimethylsulfoxide as a solvent solves this ITP shortcoming. Dimethylsulfoxide changes the pH regime of analytes and electrolytes but, more importantly, strongly reduces the proton mobility by prohibiting hydrogen bonds and thus, the so-called Zundel-Eigen-Zundel electrical conduction mechanism of flipping hydrogen bonds. The effects are demonstrated in an electrolyte system with taurine or H(+) as terminator, and imidazole as leader together with strong acids such as oxalic and even trifluoroacetic acid as counterions, both impossible to use in aqueous solution. Mass spectrometric as well as capacitively coupled contactless conductivity detection (C(4)D) are used to follow the ITP processes. To demonstrate the preconcentration capabilities of ITP in a two-dimensional set-up, we, here, also demonstrate that our non-aqueous ITP method can be combined with capillary electrophoresis-mass spectrometry in a column-coupling system using a hybrid approach of capillaries coupled to a microfluidic interface. For this, C(4)D was optimized for on-chip detection with the electrodes aligned on top of a thin glass lid of the microfluidic chip.

  19. Strongly coupled plasma research for the equation of state and conductivity of a laser-compressed electron-ion plasma. Final report, 1 January 1976-31 December 1980

    SciTech Connect

    Kalman, G.; Golden, K.I.; Bakshi, P.

    1981-08-15

    A novel scheme for the analysis of dense, strongly coupled plasmas, occurring in laser compression (and other) experiments, has been developed. The scheme has been applied to the analysis both of static and of dynamic properties of such plasmas. Comparison with conventional perturbative weak coupling theories and with other strong coupling schemes have been performed. They confirm the superiority of the present scheme.

  20. Synergetic use of thermal and visible imaging techniques for contactless and unobtrusive breathing measurement

    NASA Astrophysics Data System (ADS)

    Hu, Meng-Han; Zhai, Guang-Tao; Li, Duo; Fan, Ye-Zhao; Chen, Xiao-Hui; Yang, Xiao-Kang

    2017-03-01

    We present a dual-mode imaging system operating on visible and long-wave infrared wavelengths for achieving the noncontact and nonobtrusive measurements of breathing rate and pattern, no matter whether the subjects use the nose and mouth simultaneously, alternately, or individually when they breathe. The improved classifiers in tandem with the biological characteristics outperformed the custom cascade classifiers using the Viola-Jones algorithm for the cross-spectrum detection of face and nose as well as mouth. In terms of breathing rate estimation, the results obtained by this system were verified to be consistent with those measured by reference method via the Bland-Altman plot with 95% limits of agreement from -2.998 to 2.391 and linear correlation analysis with a correlation coefficient of 0.971, indicating that this method was acceptable for the quantitative analysis of breathing. In addition, the breathing waveforms extracted by the dual-mode imaging system were basically the same as the corresponding standard breathing sequences. Since the validation experiments were conducted under challenging conditions, such as the significant positional and abrupt physiological variations, we stated that this dual-mode imaging system utilizing the respective advantages of RGB and thermal cameras was a promising breathing measurement tool for residential care and clinical applications.

  1. Comparison of different coil positions for ventilation monitoring with contact-less magnetic impedance measurements

    NASA Astrophysics Data System (ADS)

    Cordes, A.; Pollig, D.; Leonhardt, S.

    2010-04-01

    For monitoring the health status of individuals, proper monitoring of ventilation is desirable. Therefore, a continuous measurement technique is an advantage for many patients since it allows personal home care scenarios. As an example, monitoring of elderly people at home could enable them to live in their familiar environment on their own with the safety of a continuous monitoring. Therefore, a measurement technique without the restriction of mobility is required. Since it is possible to monitor ventilation with magnetic impedance measurements without conductive contact, this technique is well suited for the mentioned scenario. Integrated in a chair, a person's health state could be monitored in many situations, e.g. during meals, while watching TV or reading a book. In this paper, we compare different positions of coil arrays for a magnetic impedance measurement system integrated in a chair in order to monitor ventilation continuously. For limiting the costs and technical complexity of the magnetic impedance measurement system, we have a focus on coil configurations with one RF channel. To limit the needed space and thickness of the array in the backrest, planar gradiometer coil setups are investigated. All measurements will be performed with a new developed portable magnetic impedance measurement system and a standard office chair.

  2. Anisotropic heat conduction in silicon nanowire network revealed by Raman scattering

    NASA Astrophysics Data System (ADS)

    Isaiev, Mykola; Didukh, Oles; Nychyporuk, Tetyana; Timoshenko, Victor; Lysenko, Vladimir

    2017-01-01

    Anisotropic nanomaterials possess interesting thermal transport properties because they allow orientation of heat fluxes along preferential directions due to a high ratio (up to three orders of magnitude) between their in-plane and cross-plane thermal conductivities. Among different techniques allowing thermal conductivity evaluation, micro-Raman scattering is known to be one of the most efficient contactless measurement approaches. In this letter, an experimental approach based on Raman scattering measurements with variable laser spot sizes is reported. Correlation between experimental and calculated thermal resistances of one-dimensional nanocrystalline solids allows a simultaneous estimation of their in-plane and cross-plane thermal conductivities. In particular, our measurement approach is illustrated to be applied for anisotropic thermal conductivity evaluation of silicon nanowire arrays.

  3. Conduct disorder

    MedlinePlus

    ... activity. Causes Conduct disorder has been linked to: Child abuse Drug or alcohol abuse in the parents Family ... 2016:chap 23. Read More Antisocial personality disorder Child abuse - physical Review Date 3/4/2015 Updated by: ...

  4. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  5. Conduct Disorder

    MedlinePlus

    ... brain damage, child abuse or neglect, genetic vulnerability, school failure, and traumatic life experiences . Children or adolescents with conduct disorder may exhibit some of the following behaviors: Aggression to people and animals bullies , threatens or intimidates ...

  6. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  7. Direct analysis of formate in human plasma, serum and whole blood by in-line coupling of microdialysis to capillary electrophoresis for rapid diagnosis of methanol poisoning.

    PubMed

    Kubáň, Pavel; Boček, Petr

    2013-03-20

    A simple method using direct injection of human blood samples and quantitative analysis of formate was developed for rapid diagnosis of methanol poisoning. A sample pretreatment device including a 500Da molecular weight cut-off dialysis membrane was in-line coupled to capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D). 50μL of 1:9 diluted blood samples and 50μL of DI water were filled into the donor and the acceptor chamber, respectively, and small ionic species in blood samples were electrokinetically injected across the dialysis membrane directly into the separation capillary. Matrix components, such as red blood cells, proteins, lipids and other high molecular weight compounds, were retained by the dialysis membrane and did not interfere with subsequent CE separation. Formate was separated from other small anions in an optimized background electrolyte solution consisting of 20mM l-histidine and 25mM l-glutamic acid at pH 4.8. The method showed excellent analytical parameters in terms of repeatability and linearity; RSD values for migration times and peak areas at a formate concentration typical for methanol poisoning were below 0.3% and 7.4%, respectively, and linear calibration curves with correlation coefficients better than 0.999 were obtained. Limit of detection and limit of quantification were 15 and 50μM formate in original (undiluted) blood samples, respectively. The method was applied to determination of formate in serum samples of a patient diagnosed with acute methanol poisoning. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Contactless measurement of electrical parameters and estimation of current-voltage characteristics of Si solar cells using the illumination intensity dependence of lock-in carrierography (photoluminescence) images

    NASA Astrophysics Data System (ADS)

    Liu, Junyan; Melnikov, Alexander; Mandelis, Andreas

    2013-09-01

    A combined theoretical and experimental approach is reported using spectrally windowed lock-in carrierography imaging (lock-in photoluminescence) under variable illumination intensity to provide quantitative contactless measurements of key electrical parameters (photogenerated current density, Jg, open circuit voltage, VOC, and maximum power voltage, Vm) of multicrystalline silicon (m-Si) solar cells in very good agreement with standard electrical measurements. The method is based on a recently developed photocarrier radiative recombination current flux relation which links the optical and electrical characteristics of solar cells. In addition, this approach is shown to yield non-contact all-optical estimates of the solar-cell current-voltage characteristics with the conventional variable load resistance replaced by variable laser intensity.

  9. Mapping and Measuring the Microrelief of Slope Deformations Using Modern Contactless Technologies and Practical Application in Territorial Planning

    NASA Astrophysics Data System (ADS)

    Chudý, František; Slámová, Martina; Tomaštík, Julián; Kardoš, Miroslav; Tunák, Daniel; Saloň, Šimon

    2017-04-01

    Slope deformations are risks limiting economic land use potential. A national database system keeps records of slope disturbances and deformations, however, it is important to update the information mainly from the point of view of practical territorial planning, especially in the high-risk areas presented in the study. The paper explains the possibilities of applying modern methods of mapping the microrelief of slope deformations of a lower extent (up to several hundreds of m2) and using not very well known contactless technologies, which could be applied in practice due to their low-cost and low-time consuming nature. In order to create a digital model of the microrelief used to carry out the measurements we applied the method of terrestrial photogrammetry, terrestrial scanning using Lenovo Phab 2Pro. It is the first device available for users that uses the Google Tango technology. So far there have been only prototypes of devices available for the developers only. The Tango technology consists of 3 partial technologies - "depth perception" (measuring the distance to objects, nowadays it uses mainly infrared radiation), "motion tracking" (tracking the position and motion of the device using embedded sensors) and "area learning" (simply learning the area, where the device looks for same objects within already existing 3D models and real space). Even though the technology utilisation is nowadays presented mainly in the field of augmented reality and navigation in the interior, there are already some applications for collecting the point clouds in real time, which can be used in a wide spectrum of applications in exterior, which was also applied in our research. Data acquired this way can be processed in readily available software products, what enabled a high degree of automation also in our case. After comparing with the reference point field that was measured using GNSS and electronic tachymeter, we reached accuracy of point position determination from a digital

  10. Appropriate Conduct

    ERIC Educational Resources Information Center

    Di Lullo, Louis

    2004-01-01

    Many years ago when the author assumed the role of assistant principal for school climate, discipline, and attendance, he inherited many school policies and guidelines that were outdated, unfair, and without merit in the current school climate. Because the school conduct code had not been revised since the school opened in 1960, many of the…

  11. Appropriate Conduct

    ERIC Educational Resources Information Center

    Di Lullo, Louis

    2004-01-01

    Many years ago when the author assumed the role of assistant principal for school climate, discipline, and attendance, he inherited many school policies and guidelines that were outdated, unfair, and without merit in the current school climate. Because the school conduct code had not been revised since the school opened in 1960, many of the…

  12. Evaluation of Coupled Precipitator Two

    SciTech Connect

    Stone, M.E.

    1999-11-08

    The offline testing of the Coupled Precipitator Two (CP-2) has been completed. The tests were conducted and are documented. The tests were conducted at an offline test rack near the Drain Tube Test Stand facility in 672-T.

  13. Conduction apraxia.

    PubMed Central

    Ochipa, C; Rothi, L J; Heilman, K M

    1994-01-01

    A left hemisphere damaged patient with ideomotor apraxia is described, whose performance on pantomime to verbal command was superior to pantomime imitation. His reception of these same gestures (gesture naming) was spared. This syndrome has been named conduction apraxia. To account for this selective impaired performance on gesture imitation, a separation of the representations for gesture production and reception is proposed and a non-lexical gesture processing route for gesture imitation is suggested. Images PMID:7931387

  14. Aging Couple across the Curriculum

    ERIC Educational Resources Information Center

    Rull, Gary M.; Rosher, Richard B.; McCann-Stone, Nancy; Robinson, Sherry B.

    2009-01-01

    Aging Couple Across the Curriculum is a unique program designed around a couple who "age" a decade with each year of medical school. In these half-day sessions, students encounter the aging couple through a standardized patient experience. Interactive breakout sessions conducted by multidisciplinary professionals enhance student learning and…

  15. In situ spazialisation of flow laws in a fractured media with multi-parametric measurements (pressure, deformation, water conductivity) and 2d coupled hydro-mechanical (h.m) modelling.

    NASA Astrophysics Data System (ADS)

    Charmoille, A.; Cappa, F.; Guglielmie, Y.

    2003-04-01

    decreasing. The simultaneous record of deformations in the drain and joint show us that joint deformation is effective after the drain opening. It is necessarily to have a sufficient water pressure in the drain to open the joint, thus the joint deformation is strongly dependent of the water pressure in the drain. When the pressure decreases in the drain, the stress stopped on the joint, and it happens a reduction of the joint aperture which induces a pressure fall less fast than the pressure fall in the drain. In the very low permeable area of the joint, it only happens a lightly decrease of pressure. In this investigation area, the joint opening is less important than in the low permeable area. During the pressure decrease in the drain, the joint closed, and the new affected permeability only permits water to slowly flow out of the joint. Then, we induce the second pressure increase when the pressure decrease in this area doesn’t finish. The reopening of the joint with the arrivals of water induces a new pressure increase which adds to the residual pressure, thus, it happens an accumulation of pressure in the joint. This observation shows us that the flow in the fractured media isn’t governed by the same parameters in a low permeable discontinuity or in a very permeable discontinuity. The conductivity measurements in the joint and in drain clearly highlight the channelling of a fracture plan. In this stratigraphic joint studied, the conductivity variations show the complexity of a joint surface. These variations of conductivity resulted of the water flow from one channel to another one induced by the pressure variations in the drain. The last stage of this research work consists of to analyse the hydro-mechanical (H.M) behaviour of the two studied discontinuities with the UDEC 2D numerical code. The procedures of modelling examine the coupled H.M effects of a jointed rock mass affected, in a first test, by an identical joint aperture in the network, and, in a second

  16. Measuring skin conductance over clothes.

    PubMed

    Hong, Ki Hwan; Lee, Seung Min; Lim, Yong Gyu; Park, Kwang Suk

    2012-11-01

    We propose a new method that measures skin conductance over clothes to nonintrusively monitor the changes in physiological conditions affecting skin conductance during daily activities. We selected the thigh-to-thigh current path and used an indirectly coupled 5-kHz AC current for the measurement. While varying the skin conductance by the Valsalva maneuver method, the results were compared with the traditional galvanic skin response (GSR) measured directly from the fingers. Skin conductance measured using a 5-kHz current displayed a highly negative correlation with the traditional GSR and the current measured over clothes reflected the rate of change of the conductance of the skin beneath.

  17. Reduction of the thermal conductivity in free-standing silicon nano-membranes investigated by non-invasive Raman thermometry

    NASA Astrophysics Data System (ADS)

    Chávez-Ángel, E.; Reparaz, J. S.; Gomis-Bresco, J.; Wagner, M. R.; Cuffe, J.; Graczykowski, B.; Shchepetov, A.; Jiang, H.; Prunnila, M.; Ahopelto, J.; Alzina, F.; Sotomayor Torres, C. M.

    2014-01-01

    We report on the reduction of the thermal conductivity in ultra-thin suspended Si membranes with high crystalline quality. A series of membranes with thicknesses ranging from 9 nm to 1.5 μm was investigated using Raman thermometry, a novel contactless technique for thermal conductivity determination. A systematic decrease in the thermal conductivity was observed as reducing the thickness, which is explained using the Fuchs-Sondheimer model through the influence of phonon boundary scattering at the surfaces. The thermal conductivity of the thinnest membrane with d = 9 nm resulted in (9 ± 2) W/mK, thus approaching the amorphous limit but still maintaining a high crystalline quality.

  18. Conducting a thermal conductivity survey

    NASA Technical Reports Server (NTRS)

    Allen, P. B.

    1985-01-01

    A physically transparent approximate theory of phonon decay rates is presented starting from a pair potential model of the interatomic forces in an insulator or semiconductor. The theory applies in the classical regime and relates the 3-phonon decay rate to the third derivative of the pair potential. Phonon dispersion relations do not need to be calculated, as sum rules relate all the needed quantities directly to the pair potential. The Brillouin zone averaged phonon lifetime turns out to involve a dimensionless measure of the anharmonicity multiplied by an effective density of states for 3-phonon decay. Results are given for rare gas and alkali halide crystals. For rare gases, the results are in good agreement with more elaborate perturbation calculations. Comparison to experimental data on phonon linewidths and thermal conductivity are made.

  19. Conductance of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, Supriyo; Anatram, M. P.

    1998-01-01

    The recent report of quantized conductance in a 4 m long multiwalled nanotube (MWNT) raises the exciting possibility of ballistic transport at room temperature over relatively long distances. We argue that this is made possible by the special symmetry of the eigenstates of the lowest propagating modes in metallic nanotubes which suppresses backscattering. This unusual effect is absent for the higher propagating modes so that transport is not ballistic once the bias exceeds the cut-off energy for the higher modes, which is estimated to be approximately 75 meV for nanotubes of diameter approximately 15 nm. Also, we show that the symmetry of the eigenstates can significantly affect their coupling to the reservoir and hence the contact resistance. A simple model is presented that can be used to understand the observed conductance-voltage characteristics.

  20. Helix coupling

    DOEpatents

    Ginell, W.S.

    1982-03-17

    A coupling for connecting helix members in series, which consists of a pair of U-shaped elements, one of which is attached to each helix end with the U sections of the elements interlocked. The coupling is particularly beneficial for interconnecting helical Nitinol elements utilized in thermal actuators or engines. Each coupling half is attached to the associated helix at two points, thereby providing axial load while being easily removed from the helix, and reusable.

  1. Helix coupling

    DOEpatents

    Ginell, W.S.

    1989-04-25

    A coupling for connecting helix members in series, which consists of a pair of U-shaped elements, one of which is attached to each helix end with the "U" sections of the elements interlocked. The coupling is particularly beneficial for interconnecting helical Nitinol elements utilized in thermal actuators or engines. Each coupling half is attached to the associated helix at two points, thereby providing axial load while being easily removed from the helix, and reusable.

  2. Helix coupling

    DOEpatents

    Ginell, William S.

    1989-04-25

    A coupling for connecting helix members in series, which consists of a pair of U-shaped elements, one of which is attached to each helix end with the "U" sections of the elements interlocked. The coupling is particularly beneficial for interconnecting helical Nitinol elements utilized in thermal actuators or engines. Each coupling half is attached to the associated helix at two points, thereby providing axial load while being easily removed from the helix, and reusable.

  3. Laser doppler and radar interferometer for contactless measurements on unaccessible tie-rods on monumental buildings: Santa Maria della Consolazione Temple in Todi

    NASA Astrophysics Data System (ADS)

    Gioffré, M.; Cavalagli, N.; Pepi, C.; Trequattrini, M.

    2017-01-01

    Non-contact measurements can be effectively used in civil engineering to assess the variation of structural performance with time. In the last decades this approach has received considerable interests from researchers working in the field of structural health monitoring (SHM). Indeed, non-contact measurements are very attractive because it is possible to perform non intrusive and non destructive investigations even being at a significant distance from the targets. Within this context, contactless measurements of the tie-rod vibrations in the Santa Maria della Consolazione Temple in Todi (Italy) are presented in this paper. In particular, laser vibrometer and radar interferometer measurements are used to estimate natural frequencies and mode shapes. This information is crucial to obtain the tensile axial force in the tie-rods, which can be used as an indicator of structural integrity or possible failure. Furthermore, a novel approach is proposed where drones (Unmanned Aerial Vehicles) can be successfully used to improve the effectiveness and the accuracy of the experimental activities.

  4. Radio frequency source of a weakly expanding wedge-shaped xenon ion beam for contactless removal of large-sized space debris objects.

    PubMed

    Balashov, Victor; Cherkasova, Maria; Kruglov, Kirill; Kudriavtsev, Arseny; Masherov, Pavel; Mogulkin, Andrey; Obukhov, Vladimir; Riaby, Valentin; Svotina, Victoria

    2017-08-01

    A theoretical-experimental research has been carried out to determine the characteristics of a radio frequency (RF) ion source for the generation of a weakly expanding wedge-shaped xenon ion beam. Such ion beam geometry is of interest as a prototype of an on-board ion injector for contactless "ion shepherding" by service spacecraft to remove large space debris objects from geostationary orbits. The wedge shape of the ion beam increases its range. The device described herein comprises an inductive gas discharge chamber and a slit-type three-electrode ion extraction grid (IEG) unit. Calculations of accelerating cell geometries and ion trajectories determined the dependence of beam expansion half-angle on normalized perveance based on the measurements of the spatial distributions of the xenon plasma parameters at the IEG entrance for a xenon flow rate q ≈ 0.2 mg/s and an incident RF power Pin ≤ 250 W at a driving frequency f = 2 MHz. Experimental studies showed that the ion beam, circular at the IEG exit, accepted the elliptical form at the distance of 580 mm with half-angle of beam expansion across IEG slits about 2°-3° and close to 0° along them. Thus, the obtained result proved the possibility of creating a new-generation on-board ion injector that could be used in spacecrafts for removal of debris.

  5. Radio frequency source of a weakly expanding wedge-shaped xenon ion beam for contactless removal of large-sized space debris objects

    NASA Astrophysics Data System (ADS)

    Balashov, Victor; Cherkasova, Maria; Kruglov, Kirill; Kudriavtsev, Arseny; Masherov, Pavel; Mogulkin, Andrey; Obukhov, Vladimir; Riaby, Valentin; Svotina, Victoria

    2017-08-01

    A theoretical-experimental research has been carried out to determine the characteristics of a radio frequency (RF) ion source for the generation of a weakly expanding wedge-shaped xenon ion beam. Such ion beam geometry is of interest as a prototype of an on-board ion injector for contactless "ion shepherding" by service spacecraft to remove large space debris objects from geostationary orbits. The wedge shape of the ion beam increases its range. The device described herein comprises an inductive gas discharge chamber and a slit-type three-electrode ion extraction grid (IEG) unit. Calculations of accelerating cell geometries and ion trajectories determined the dependence of beam expansion half-angle on normalized perveance based on the measurements of the spatial distributions of the xenon plasma parameters at the IEG entrance for a xenon flow rate q ≈ 0.2 mg/s and an incident RF power Pin ≤ 250 W at a driving frequency f = 2 MHz. Experimental studies showed that the ion beam, circular at the IEG exit, accepted the elliptical form at the distance of 580 mm with half-angle of beam expansion across IEG slits about 2°-3° and close to 0° along them. Thus, the obtained result proved the possibility of creating a new-generation on-board ion injector that could be used in spacecrafts for removal of debris.

  6. Gesture-Controlled Interface for Contactless Control of Various Computer Programs with a Hooking-Based Keyboard and Mouse-Mapping Technique in the Operating Room

    PubMed Central

    Park, Ben Joonyeon; Jang, Taekjin; Choi, Jong Woo; Kim, Namkug

    2016-01-01

    We developed a contactless interface that exploits hand gestures to effectively control medical images in the operating room. We developed an in-house program called GestureHook that exploits message hooking techniques to convert gestures into specific functions. For quantitative evaluation of this program, we used gestures to control images of a dynamic biliary CT study and compared the results with those of a mouse (8.54 ± 1.77 s to 5.29 ± 1.00 s; p < 0.001) and measured the recognition rates of specific gestures and the success rates of tasks based on clinical scenarios. For clinical applications, this program was set up in the operating room to browse images for plastic surgery. A surgeon browsed images from three different programs: CT images from a PACS program, volume-rendered images from a 3D PACS program, and surgical planning photographs from a basic image viewing program. All programs could be seamlessly controlled by gestures and motions. This approach can control all operating room programs without source code modification and provide surgeons with a new way to safely browse through images and easily switch applications during surgical procedures. PMID:26981146

  7. Integrated biochip for label-free and real-time detection of DNA amplification by contactless impedance measurements based on interdigitated electrodes.

    PubMed

    Fang, Xinxin; Jin, Qinghui; Jing, Fengxiang; Zhang, Huanqian; Zhang, Feng; Mao, Hongju; Xu, Baojian; Zhao, Jianlong

    2013-06-15

    Here, we introduce an integrated biochip which offers accurate thermal control and sensitive electrochemical detection of DNA amplification in real-time. The biochip includes a 10-μl microchamber, a temperature sensor, a heater, and a contactless impedance biosensor. A pair of interdigitated electrodes is employed as the impedance biosensor and the products of the amplification are determined directly through tracing the impedance change, without using any labels, redox indicators, or probes. Real-time monitoring of strand-displacement amplification and rolling circle amplification was successfully performed on the biochip and a detection limit of 1 nM was achieved. Amplification starting at an initial concentration of 10 nM could be discriminated from that starting at 1 nM started concentration as well as from the negative control. Since an insulation layer covers the electrodes, the electrodes are spared from erosion, hydrolysis and bubble formation on the surface, thus, ensuring a long lifetime and a high reusability of the sensor. In comparison to bench-top apparatus, our chip shows good efficiency, sensitivity, accuracy, and versatility. Our system requires only simple equipments and simple skills, and can easily be miniaturized into a micro-scale system. The system will then be suitable for a handheld portable device, which can be applied in remote areas. It covers merits such as low cost, low-power consumption, rapid response, real-time monitoring, label-free detection, and high-throughput detection.

  8. Feasibility of contactless 3D optical measurement for the analysis of bone and soft tissue lesions: new technologies and perspectives in forensic sciences.

    PubMed

    Sansoni, Giovanna; Cattaneo, Cristina; Trebeschi, Marco; Gibelli, Daniele; Porta, Davide; Picozzi, Massimo

    2009-05-01

    In forensic pathology and anthropology, a correct analysis of lesions on soft tissues and bones is of the utmost importance, in order to verify the cause and manner of death. Photographs, videos, and photogrammetry may be an optimal manner of immortalizing a lesion, both on cadavers and skeletal remains; however, none of these can supply a detailed three-dimensional (3D) modeling of the lesion. Up to now, only the use of casts has given us the possibility of studying deep lesions such as saw marks with an accurate and complete 3D reconstruction of bone structure. The present study aims at verifying the applicability of 3D optical contactless measurement for the accurate recording of soft tissue and bone lesions, in order to develop a unique and precise method of registering and analyzing lesions, both in forensic pathology and anthropology. Three cases were analyzed: the first, a car accident with blunt force skin injuries; the second, a murder with blunt force injury to the head applied with a metal rod; the third, a series of sharp force knife and saw lesions on bone. Results confirm that 3D optical digitizing technology is a crucial tool in the immortalization of wound morphology in the medico-legal context even on "difficult" substrates such as cut marks and saw marks on bone.

  9. Gesture-Controlled Interface for Contactless Control of Various Computer Programs with a Hooking-Based Keyboard and Mouse-Mapping Technique in the Operating Room.

    PubMed

    Park, Ben Joonyeon; Jang, Taekjin; Choi, Jong Woo; Kim, Namkug

    2016-01-01

    We developed a contactless interface that exploits hand gestures to effectively control medical images in the operating room. We developed an in-house program called GestureHook that exploits message hooking techniques to convert gestures into specific functions. For quantitative evaluation of this program, we used gestures to control images of a dynamic biliary CT study and compared the results with those of a mouse (8.54 ± 1.77 s to 5.29 ± 1.00 s; p < 0.001) and measured the recognition rates of specific gestures and the success rates of tasks based on clinical scenarios. For clinical applications, this program was set up in the operating room to browse images for plastic surgery. A surgeon browsed images from three different programs: CT images from a PACS program, volume-rendered images from a 3D PACS program, and surgical planning photographs from a basic image viewing program. All programs could be seamlessly controlled by gestures and motions. This approach can control all operating room programs without source code modification and provide surgeons with a new way to safely browse through images and easily switch applications during surgical procedures.

  10. Use of micro-photoluminescence as a contactless measure of the 2D electron density in a GaAs quantum well

    NASA Astrophysics Data System (ADS)

    Kamburov, D.; Baldwin, K. W.; West, K. W.; Lyon, S.; Pfeiffer, L. N.; Pinczuk, A.

    2017-06-01

    We compare micro-photoluminescence (μPL) as a measure of the electron density in a clean, two-dimensional (2D) system confined in a GaAs quantum well (QW) to the standard magneto-transport technique. Our study explores the PL shape evolution across a number of molecular beam epitaxy-grown samples with different QW widths and 2D electron densities and notes its correspondence with the density obtained in magneto-transport measurements on these samples. We also measure the 2D density in a top-gated quantum well sample using both PL and transport and find that the two techniques agree to within a few percent over a wide range of gate voltages. We find that the PL measurements are sensitive to gate-induced 2D density changes on the order of 109 electrons/cm2. The spatial resolution of the PL density measurement in our experiments is 40 μm, which is already substantially better than the millimeter-scale resolution now possible in spatial density mapping using magneto-transport. Our results establish that μPL can be used as a reliable high spatial resolution technique for future contactless measurements of density variations in a 2D electron system.

  11. Shape memory thermal conduction switch

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, Rajan (Inventor); Krishnan, Vinu (Inventor); Notardonato, William U. (Inventor)

    2010-01-01

    A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

  12. Conductivity in an anisotropic background

    SciTech Connect

    Lee, Bum-Hoon; Nam, Siyoung; Pang, Da-Wei; Park, Chanyong

    2011-03-15

    By using the gauge/gravity duality, we investigate the dual field theories of the anisotropic backgrounds, which are exact solutions of Einstein-Maxwell-dilaton theory with a Liouville potential. When we turn on the bulk gauge field fluctuation A{sub x} with a nontrivial dilaton coupling, the AC conductivity of this dual field theory is proportional to the frequency with an exponent depending on parameters of the anisotropic background. In some parameter regions, we find that this conductivity can have the negative exponent like the strange metal. In addition, we also investigate another U(1) gauge field fluctuation, which is not coupled with a dilaton field. We classify all possible conductivities of this system and find that the exponent of the conductivity is always positive.

  13. Free carrier lifetime determination using time-resolved microwave conductivity: methods and implications for devices

    NASA Astrophysics Data System (ADS)

    Oosterhout, Stefan; Owczarczyk, Zbyslaw; Braunecker, Wade; Kopidakis, Nikos; Larsen, Ross; Ginley, David; Olson, Dana

    2014-03-01

    Optimizing devices for high performance is a time consuming, tedious task. Many polymers that have been synthesized over the last decade, have been employed in devices and proved to have a low power conversion efficiency only after a tedious device optimization experiment. A good free carrier lifetime in polymer organic photovoltaic devices is essential for decent device performance. This characteristic of polymer donor and fullerene acceptor bulk heterojunctions can be determined prior to device fabrication using the contactless time-resolved microwave conductivity (TRMC), eliminating the need for time-consuming device optimization experiments when the free carrier lifetime is low. This presentation focuses on how TRMC is utilized for screening potential new materials for OPV, and methods for a figure-of-merit for charge carrier lifetime is discussed.

  14. Monitoring of Plant Light/Dark Cycles Using Air-coupled Ultrasonic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Fariñas, M. D.; Sancho-Knapik, D.; Peguero-Pina, J.; Gil-Pelegrín, E.; Álvarez-Arenas, T. E. G.

    This work presents the application of a technique based on the excitation, sensing and spectral analysis of leaves thickness resonances using air-coupled and wide-band ultrasound to monitor variations in leaves properties due to the plant response along light/dark cycles. The main features of these resonances are determined by the tautness of the cells walls in such a way that small modifications produced by variations in the transpiration rate, stomata aperture or water potential have a direct effect on the thickness resonances that can be measured in a completely non-invasive and contactless way. Results show that it is possible to monitor leaves changes due to variations in light intensity along the diurnal cycle, moreover, the technique reveals differences in the leaf response for different species and also within the same species but for specimens grown under different conditions that present different cell structures at the tissue level.

  15. Wireless contactless pressure measurement of an LC passive pressure sensor with a novel antenna for high-temperature applications

    NASA Astrophysics Data System (ADS)

    Li, Chen; Tan, Qiu-Lin; Xue, Chen-Yang; Zhang, Wen-Dong; Li, Yun-Zhi; Xiong, Ji-Jun

    2015-04-01

    In this paper, a novel antenna is proposed for high-temperature testing, which can make the high-temperature pressure characteristics of a wireless passive ceramic pressure sensor demonstrated at up to a temperature of 600 °C. The design parameters of the antenna are similar to those of the sensor, which will increase the coupling strength between the sensor and testing antenna. The antenna is fabricated in thick film integrated technology, and the properties of the alumina ceramic and silver ensure the feasibility of the antenna in high-temperature environments. The sensor, coupled with the ceramic antenna, is investigated using a high-temperature pressure testing platform. The experimental measurement results show that the pressure signal in a harsh environment can be detected by the frequency diversity of the sensor. Project supported by the National Natural Science Foundation for Distinguished Young Scholars, China (Grant No. 51425505), the National Natural Science Foundation of China (Grant No. 61471324), the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi Province, China (Grant No. 2013-077), and the Graduate Students Outstanding Innovation Project of Shanxi Province, China (Grant No. 20143020).

  16. Nonadiabatic Coupling

    NASA Astrophysics Data System (ADS)

    Kryachko, Eugene S.

    The general features of the nonadiabatic coupling and its relation to molecular properties are surveyed. Some consequences of the [`]equation of motion', formally expressing a [`]smoothness' of a given molecular property within the diabatic basis, are demonstrated. A particular emphasis is made on the relation between a [`]smoothness' of the electronic dipole moment and the generalized Mulliken-Hush formula for the diabatic electronic coupling.

  17. Synergistic Coupling between Li6.75La3Zr1.75Ta0.25O12 and Poly(vinylidene fluoride) Induces High Ionic Conductivity, Mechanical Strength, and Thermal Stability of Solid Composite Electrolytes.

    PubMed

    Zhang, Xue; Liu, Ting; Zhang, Shuofeng; Huang, Xin; Xu, Bingqing; Lin, Yuanhua; Xu, Ben; Li, Liangliang; Nan, Ce-Wen; Shen, Yang

    2017-10-04

    Easy processing and flexibility of polymer electrolytes make them very promising in developing all-solid-state lithium batteries. However, their low room-temperature conductivity and poor mechanical and thermal properties still hinder their applications. Here, we use Li6.75La3Zr1.75Ta0.25O12 (LLZTO) ceramics to trigger structural modification of poly(vinylidene fluoride) (PVDF) polymer electrolyte. By combining experiments and first-principle calculations, we find that La atom of LLZTO could complex with the N atom and C═O group of solvent molecules such as N,N-dimethylformamide along with electrons enriching at the N atom, which behaves like a Lewis base and induces the chemical dehydrofluorination of the PVDF skeleton. Partially modified PVDF chains activate the interactions between the PVDF matrix, lithium salt, and LLZTO fillers, hence leading to significantly improved performance of the flexible electrolyte membrane (e.g., a high ionic conductivity of about 5 × 10(-4) S cm(-1) at 25 °C, high mechanical strength, and good thermal stability). For further illustration, a solid-state lithium battery of LiCoO2|PVDF-based membrane|Li is fabricated and delivers satisfactory rate capability and cycling stability at room temperature. Our study indicates that the LLZTO modifying PVDF membrane is a promising electrolyte used for all-solid-state lithium batteries.

  18. Heat conduction in conducting polyaniline nanofibers

    NASA Astrophysics Data System (ADS)

    Nath, Chandrani; Kumar, A.; Syu, K.-Z.; Kuo, Y.-K.

    2013-09-01

    Thermal conductivity and specific heat of conducting polyaniline nanofibers are measured to identify the nature of heat carrying modes combined with their inhomogeneous structure. The low temperature thermal conductivity results reveal crystalline nature while the high temperature data confirm the amorphous nature of the material suggesting heterogeneous model for conducting polyaniline. Extended acoustic phonons dominate the low temperature (<100 K) heat conduction, while localized optical phonons hopping, assisted by the extended acoustic modes, account for the high temperature (>100 K) heat conduction.

  19. FLEXIBLE COUPLING

    DOEpatents

    Babelay, E.F.

    1962-02-13

    A flexible shaft coupling for operation at speeds in excess of 14,000 rpm is designed which requires no lubrication. A driving sleeve member and a driven sleeve member are placed in concentric spaced relationship. A torque force is transmitted to the driven member from the driving member through a plurality of nylon balls symmetrically disposed between the spaced sleeves. The balls extend into races and recesses within the respective sleeve members. The sleeve members have a suitable clearance therebetween and the balls have a suitable radial clearance during operation of the coupling to provide a relatively loose coupling. These clearances accommodate for both parallel and/or angular misalignments and avoid metal-tometal contact between the sleeve members during operation. Thus, no lubrication is needed, and a minimum of vibrations is transmitted between the sleeve members. (AEC)

  20. Prosthesis coupling

    NASA Technical Reports Server (NTRS)

    Reswick, J. B.; Mooney, V.; Bright, C. W.; Owens, L. J. (Inventor)

    1979-01-01

    A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump.

  1. Conductivity-limiting bipolar thermal conductivity in semiconductors

    PubMed Central

    Wang, Shanyu; Yang, Jiong; Toll, Trevor; Yang, Jihui; Zhang, Wenqing; Tang, Xinfeng

    2015-01-01

    Intriguing experimental results raised the question about the fundamental mechanisms governing the electron-hole coupling induced bipolar thermal conduction in semiconductors. Our combined theoretical analysis and experimental measurements show that in semiconductors bipolar thermal transport is in general a “conductivity-limiting” phenomenon, and it is thus controlled by the carrier mobility ratio and by the minority carrier partial electrical conductivity for the intrinsic and extrinsic cases, respectively. Our numerical method quantifies the role of electronic band structure and carrier scattering mechanisms. We have successfully demonstrated bipolar thermal conductivity reduction in doped semiconductors via electronic band structure modulation and/or preferential minority carrier scatterings. We expect this study to be beneficial to the current interests in optimizing thermoelectric properties of narrow gap semiconductors. PMID:25970560

  2. Conductance fluctuations in nanostructures

    NASA Astrophysics Data System (ADS)

    Zhu, Ningjia

    1997-12-01

    -statistics of the scattering states satisfies the same universality class as those of the bound states. This provides a practical means of measuring the chaotic scattering from transport experiments. Finally, I studied a ballistic system without any impurities: a window-coupled quantum wire. This system has the ability of switching electric current from one wire to the other quantum mechanically. I have made a systematic study of the complicated magneto-conductance fluctuations observed in this system experimentally. My theoretical results are in qualitative agreement with the measurements, and they provide the much needed understanding of the physics controlling these oscillations.

  3. Ion conductance in electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Chandra, Amalendu; Bagchi, Biman

    1999-05-01

    We develop a new theoretical formulation to study ion conductance in electrolyte solutions, based on a mode coupling theory treatment of the electrolyte friction. The new theory provides expressions for both the ion atmosphere relaxation and electrophoretic contributions to the total electrolyte friction that acts on a moving ion. While the ion atmosphere relaxation term arises from the time-dependent microscopic interaction of the moving ion with the surrounding ions in the solution, the electrophoretic term originates from the coupling of the ion's velocity to the collective current mode of the ion atmosphere. Mode coupling theory, combined with time-dependent density functional theory of ion atmosphere fluctuations, leads to self-consistent expressions for these two terms which also include the effects of self-motion of the ion under consideration. These expressions have been solved for the concentration dependence of electrolyte friction and ion conductance. It is shown that in the limit of very low ion concentration, the present theory correctly reduces to the well-known Debye-Huckel-Onsager limiting law which predicts a linear dependence of conductance on the square root of ion concentration (c). At moderate and high concentrations, the present theory predicts a significant nonlinear and weaker dependence on √c which is in very good agreement with experimental results. The present theory is self-contained and does not involve any adjustable parameter.

  4. Thermal conductivity of supercooled water.

    PubMed

    Biddle, John W; Holten, Vincent; Sengers, Jan V; Anisimov, Mikhail A

    2013-04-01

    The heat capacity of supercooled water, measured down to -37°C, shows an anomalous increase as temperature decreases. The thermal diffusivity, i.e., the ratio of the thermal conductivity and the heat capacity per unit volume, shows a decrease. These anomalies may be associated with a hypothesized liquid-liquid critical point in supercooled water below the line of homogeneous nucleation. However, while the thermal conductivity is known to diverge at the vapor-liquid critical point due to critical density fluctuations, the thermal conductivity of supercooled water, calculated as the product of thermal diffusivity and heat capacity, does not show any sign of such an anomaly. We have used mode-coupling theory to investigate the possible effect of critical fluctuations on the thermal conductivity of supercooled water and found that indeed any critical thermal-conductivity enhancement would be too small to be measurable at experimentally accessible temperatures. Moreover, the behavior of thermal conductivity can be explained by the observed anomalies of the thermodynamic properties. In particular, we show that thermal conductivity should go through a minimum when temperature is decreased, as Kumar and Stanley observed in the TIP5P model of water. We discuss physical reasons for the striking difference between the behavior of thermal conductivity in water near the vapor-liquid and liquid-liquid critical points.

  5. Quantum transport with two interacting conduction channels.

    PubMed

    White, Alexander J; Migliore, Agostino; Galperin, Michael; Nitzan, Abraham

    2013-05-07

    The transport properties of a conduction junction model characterized by two mutually coupled channels that strongly differ in their couplings to the leads are investigated. Models of this type describe molecular redox junctions (where a level that is weakly coupled to the leads controls the molecular charge, while a strongly coupled one dominates the molecular conduction), and electron counting devices in which the current in a point contact is sensitive to the charging state of a nearby quantum dot. Here we consider the case where transport in the strongly coupled channel has to be described quantum mechanically (covering the full range between sequential tunneling and co-tunneling), while conduction through the weakly coupled channel is a sequential process that could by itself be described by a simple master equation. We compare the result of a full quantum calculation based on the pseudoparticle non-equilibrium Green function method to that obtained from an approximate mixed quantum-classical calculation, where correlations between the channels are taken into account through either the averaged rates or the averaged energy. We find, for the steady state current, that the approximation based on the averaged rates works well in most of the voltage regime, with marked deviations from the full quantum results only at the threshold for charging the weekly coupled level. These deviations are important for accurate description of the negative differential conduction behavior that often characterizes redox molecular junctions in the neighborhood of this threshold.

  6. An enhanced feature set for pattern recognition based contrast enhancement of contact-less captured latent fingerprints in digitized crime scene forensics

    NASA Astrophysics Data System (ADS)

    Hildebrandt, Mario; Kiltz, Stefan; Dittmann, Jana; Vielhauer, Claus

    2014-02-01

    In crime scene forensics latent fingerprints are found on various substrates. Nowadays primarily physical or chemical preprocessing techniques are applied for enhancing the visibility of the fingerprint trace. In order to avoid altering the trace it has been shown that contact-less sensors offer a non-destructive acquisition approach. Here, the exploitation of fingerprint or substrate properties and the utilization of signal processing techniques are an essential requirement to enhance the fingerprint visibility. However, especially the optimal sensory is often substrate-dependent. An enhanced generic pattern recognition based contrast enhancement approach for scans of a chromatic white light sensor is introduced in Hildebrandt et al.1 using statistical, structural and Benford's law2 features for blocks of 50 micron. This approach achieves very good results for latent fingerprints on cooperative, non-textured, smooth substrates. However, on textured and structured substrates the error rates are very high and the approach thus unsuitable for forensic use cases. We propose the extension of the feature set with semantic features derived from known Gabor filter based exemplar fingerprint enhancement techniques by suggesting an Epsilon-neighborhood of each block in order to achieve an improved accuracy (called fingerprint ridge orientation semantics). Furthermore, we use rotation invariant Hu moments as an extension of the structural features and two additional preprocessing methods (separate X- and Y Sobel operators). This results in a 408-dimensional feature space. In our experiments we investigate and report the recognition accuracy for eight substrates, each with ten latent fingerprints: white furniture surface, veneered plywood, brushed stainless steel, aluminum foil, "Golden-Oak" veneer, non-metallic matte car body finish, metallic car body finish and blued metal. In comparison to Hildebrandt et al.,1 our evaluation shows a significant reduction of the error rates

  7. Effect of inter-tissue inductive coupling on multi-frequency imaging of intracranial hemorrhage by magnetic induction tomography

    NASA Astrophysics Data System (ADS)

    Xiao, Zhili; Tan, Chao; Dong, Feng

    2017-08-01

    Magnetic induction tomography (MIT) is a promising technique for continuous monitoring of intracranial hemorrhage due to its contactless nature, low cost and capacity to penetrate the high-resistivity skull. The inter-tissue inductive coupling increases with frequency, which may lead to errors in multi-frequency imaging at high frequency. The effect of inter-tissue inductive coupling was investigated to improve the multi-frequency imaging of hemorrhage. An analytical model of inter-tissue inductive coupling based on the equivalent circuit was established. A set of new multi-frequency decomposition equations separating the phase shift of hemorrhage from other brain tissues was derived by employing the coupling information to improve the multi-frequency imaging of intracranial hemorrhage. The decomposition error and imaging error are both decreased after considering the inter-tissue inductive coupling information. The study reveals that the introduction of inter-tissue inductive coupling can reduce the errors of multi-frequency imaging, promoting the development of intracranial hemorrhage monitoring by multi-frequency MIT.

  8. Proton conducting membrane for fuel cells

    DOEpatents

    Colombo, Daniel G.; Krumpelt, Michael; Myers, Deborah J.; Kopasz, John P.

    2007-03-27

    An ion conducting membrane comprising dendrimeric polymers covalently linked into a network structure. The dendrimeric polymers have acid functional terminal groups and may be covalently linked via linking compounds, cross-coupling reactions, or copolymerization reactions. The ion conducting membranes may be produced by various methods and used in fuel cells.

  9. Proton conducting membrane for fuel cells

    DOEpatents

    Colombo, Daniel G.; Krumpelt, Michael; Myers, Deborah J.; Kopasz, John P.

    2005-12-20

    An ion conducting membrane comprising dendrimeric polymers covalently linked into a network structure. The dendrimeric polymers have acid functional terminal groups and may be covalently linked via linking compounds, cross-coupling reactions, or copolymerization reactions. The ion conducting membranes may be produced by various methods and used in fuel cells.

  10. Tubular Coupling

    NASA Technical Reports Server (NTRS)

    Rosenbaum, Bernard J. (Inventor)

    2000-01-01

    A system for coupling a vascular overflow graft or cannula to a heart pump. A pump pipe outlet is provided with an external tapered surface which receives the end of a compressible connula. An annular compression ring with a tapered internal bore surface is arranged about the cannula with the tapered internal surface in a facing relationship to the external tapered surface. The angle of inclination of the tapered surfaces is converging such that the spacing between the tapered surfaces decreases from one end of the external tapered surface to the other end thereby providing a clamping action of the tapered surface on a cannula which increases as a function of the length of cannula segment between the tapered surfaces. The annular compression ring is disposed within a tubular locking nut which threadedly couples to the pump and provides a compression force for urging the annular ring onto the cannula between the tapered surfaces. The nut has a threaded connection to the pump body. The threaded coupling to the pump body provides a compression force for the annular ring. The annular ring has an annular enclosure space in which excess cannula material from the compression between the tapered surfaces to "bunch up" in the space and serve as an enlarged annular ring segment to assist holding the cannula in place. The clamped cannula provides a seamless joint connection to the pump pipe outlet where the clamping force is uniformly applied to the cannula because of self alignment of the tapered surfaces. The nut can be easily disconnected to replace the pump if necessary.

  11. Magnetoelectric coupling at metal surfaces.

    PubMed

    Gerhard, L; Yamada, T K; Balashov, T; Takács, A F; Wesselink, R J H; Däne, M; Fechner, M; Ostanin, S; Ernst, A; Mertig, I; Wulfhekel, W

    2010-11-01

    Magnetoelectric coupling allows the magnetic state of a material to be changed by an applied electric field. To date, this phenomenon has mainly been observed in insulating materials such as complex multiferroic oxides. Bulk metallic systems do not exhibit magnetoelectric coupling, because applied electric fields are screened by conduction electrons. We demonstrate strong magnetoelectric coupling at the surface of thin iron films using the electric field from a scanning tunnelling microscope, and are able to write, store and read information to areas with sides of a few nanometres. Our work demonstrates that high-density, non-volatile information storage is possible in metals.

  12. Conductive magnetorheological elastomer: fatigue dependent impedance-mechanic coupling properties

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Xuan, Shouhu; Ge, Lin; Wen, Qianqian; Gong, Xinglong

    2017-01-01

    This work investigated the relationship between the impedance properties and dynamic mechanical properties of magnetorheological elastomers (MREs) under fatigue loading. The storage modulus and the impedance properties of MREs were highly influenced by the pressure and magnetic field. Under the same experimental condition, the two characteristics exhibited similar fatigue dependent change trends. When pressure was smaller than 10 N, the capacitance of MRE could be divided into four sections with the increase of the cyclic numbers. The relative equivalent circuit model was established to fit the experimental results of the impedance spectra. Each parameter of circuit element reflected the change of fatigue loading, relative microstructure of MRE, MRE-electrode interface layer, respectively. Based on the above analysis, the real-time and nondestructive impedance method was demonstrated to be high potential on detecting the fatigue of the MRE device.

  13. Toward nanofluids of ultra-high thermal conductivity.

    PubMed

    Wang, Liqiu; Fan, Jing

    2011-02-18

    The assessment of proposed origins for thermal conductivity enhancement in nanofluids signifies the importance of particle morphology and coupled transport in determining nanofluid heat conduction and thermal conductivity. The success of developing nanofluids of superior conductivity depends thus very much on our understanding and manipulation of the morphology and the coupled transport. Nanofluids with conductivity of upper Hashin-Shtrikman (H-S) bound can be obtained by manipulating particles into an interconnected configuration that disperses the base fluid and thus significantly enhancing the particle-fluid interfacial energy transport. Nanofluids with conductivity higher than the upper H-S bound could also be developed by manipulating the coupled transport among various transport processes, and thus the nature of heat conduction in nanofluids. While the direct contributions of ordered liquid layer and particle Brownian motion to the nanofluid conductivity are negligible, their indirect effects can be significant via their influence on the particle morphology and/or the coupled transport.

  14. Dark coupling

    SciTech Connect

    Gavela, M.B.; Hernández, D.; Honorez, L. Lopez; Mena, O.; Rigolin, S. E-mail: d.hernandez@uam.es E-mail: omena@ific.uv.es

    2009-07-01

    The two dark sectors of the universe—dark matter and dark energy—may interact with each other. Background and linear density perturbation evolution equations are developed for a generic coupling. We then establish the general conditions necessary to obtain models free from non-adiabatic instabilities. As an application, we consider a viable universe in which the interaction strength is proportional to the dark energy density. The scenario does not exhibit ''phantom crossing'' and is free from instabilities, including early ones. A sizeable interaction strength is compatible with combined WMAP, HST, SN, LSS and H(z) data. Neutrino mass and/or cosmic curvature are allowed to be larger than in non-interacting models. Our analysis sheds light as well on unstable scenarios previously proposed.

  15. Thermoacoustic couple

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1983-10-04

    An apparatus and method for determining acoustic power density level and its direction in a fluid using a single sensor are disclosed. The preferred embodiment of the apparatus, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas.

  16. Contactless electroreflectance and theoretical studies of band gap and spin-orbit splitting in InP{sub 1−x}Bi{sub x} dilute bismide with x ≤ 0.034

    SciTech Connect

    Kopaczek, J.; Kudrawiec, R. Polak, M. P.; Scharoch, P.; Birkett, M.; Veal, T. D.; Wang, K.; Gu, Y.; Gong, Q.; Wang, S.

    2014-12-01

    Contactless electroreflectance is applied to study the band gap (E{sub 0}) and spin-orbit splitting (Δ{sub SO}) in InP{sub 1−x}Bi{sub x} alloys with 0 < x ≤ 0.034. The E{sub 0} transition shifts to longer wavelengths very significantly (−83 meV/% Bi), while the E{sub 0} + Δ{sub SO} transition shifts very weakly (−13 meV/% Bi) with the rise of Bi concentration. These changes in energies of optical transitions are discussed in the context of the valence band anticrossing model and ab initio calculations. Shifts of E{sub 0} and E{sub 0} + Δ{sub SO} transitions, obtained within ab-initio calculations, are −106 and −20 meV per % Bi, respectively, which is in a good agreement with experimental results.

  17. Thermal conductivity and air-mediated losses in periodic porous silicon membranes at high temperatures.

    PubMed

    Graczykowski, B; El Sachat, A; Reparaz, J S; Sledzinska, M; Wagner, M R; Chavez-Angel, E; Wu, Y; Volz, S; Wu, Y; Alzina, F; Sotomayor Torres, C M

    2017-09-04

    Heat conduction in silicon can be effectively engineered by means of sub-micrometre porous thin free-standing membranes. Tunable thermal properties make these structures good candidates for integrated heat management units such as waste heat recovery, rectification or efficient heat dissipation. However, possible applications require detailed thermal characterisation at high temperatures which, up to now, has been an experimental challenge. In this work we use the contactless two-laser Raman thermometry to study heat dissipation in periodic porous membranes at high temperatures via lattice conduction and air-mediated losses. We find the reduction of the thermal conductivity and its temperature dependence closely correlated with the structure feature size. On the basis of two-phonon Raman spectra, we attribute this behaviour to diffuse (incoherent) phonon-boundary scattering. Furthermore, we investigate and quantify the heat dissipation via natural air-mediated cooling, which can be tuned by engineering the porosity.Nanostructuring of silicon allows acoustic phonon engineering, but the mechanism of related thermal transport in these structures is not fully understood. Here, the authors study the heat dissipation in silicon membranes with periodic nanoholes and show the importance of incoherent scattering.

  18. Non Destructive Testing by active infrared thermography coupled with shearography under same optical heat excitation

    NASA Astrophysics Data System (ADS)

    Theroux, Louis-Daniel; Dumoulin, Jean; Maldague, Xavier

    2014-05-01

    As infrastructures are aging, the evaluation of their health is becoming crucial. To do so, numerous Non Destructive Testing (NDT) methods are available. Among them, thermal shearography and active infrared thermography represent two full field and contactless methods for surface inspection. The synchronized use of both methods presents multiples advantages. Most importantly, both NDT are based on different material properties. Thermography depend on the thermal properties and shearography on the mechanical properties. The cross-correlation of both methods result in a more accurate and exact detection of the defects. For real site application, the simultaneous use of both methods is simplified due to the fact that the excitation method (thermal) is the same. Active infrared thermography is the measure of the temperature by an infrared camera of a surface subjected to heat flux. Observation of the variation of temperature in function of time reveal the presence of defects. On the other hand, shearography is a measure of out-of-plane surface displacement. This displacement is caused by the application of a strain on the surface which (in our case) take the form of a temperature gradient inducing a thermal stress To measure the resulting out-of-plane displacement, shearography exploit the relation between the phase difference and the optical path length. The phase difference is measured by the observation of the interference between two coherent light beam projected on the surface. This interference is due to change in optical path length as the surface is deformed [1]. A series of experimentation have been conducted in laboratory with various sample of concrete reinforced with CFRP materials. Results obtained reveal that with both methods it was possible to detect defects in the gluing. An infrared lamp radiating was used as the active heat source. This is necessary if measurements with shearography are to be made during the heating process. A heating lamp in the

  19. On Vasyliunas's equivalent conductivity formalism

    NASA Technical Reports Server (NTRS)

    Pontius, D. H., Jr.

    1992-01-01

    The Vasyliunas's (1972) equivalent conductivity formalism (ECF) for representing the coupling of the ionosphere and the magnetosphere is discussed, and a new, simpler, derivation is presented of the ECF, in which certain of the underlying assumptions and their implications are made transparent. The derivation presented indicates that the only role of the ions in the ECF is to insure quasi-neutrality. It is shown that the ECF is not as robust as usually assumed and that caution must be used to insure that reasonable results are obtained.

  20. Fabrication of glass microchannels by xurography for electrophoresis applications.

    PubMed

    Pessoa de Santana, Phillipe; Segato, Thiago Pinotti; Carrilho, Emanuel; Lima, Renato Sousa; Dossi, Nicolò; Kamogawa, Marcos Yassuo; Gobbi, Angelo Luiz; Piazzeta, Maria Helena; Piccin, Evandro

    2013-03-21

    This communication describes a simple and cost-effective method for fabricating glass microchannels by wet chemical etching using masks made by xurography in vinyl adhesive films. Analytical performance of microfluidic devices fabricated using the new approach was evaluated by microchip electrophoresis coupled to capacitively coupled contactless conductivity detection (C(4)D) and laser-induced fluorescence (LIF) detection.