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Sample records for switch detecting liquid

  1. A Simple Opto-Fluidic Switch Detecting Liquid Filling in Polymer-Based Microfluidic Systems

    DEFF Research Database (Denmark)

    Bundgaard, Frederik; Geschke, Oliver; Zengerle, R

    2007-01-01

    A novel detection scheme for detection of liquid levels and bubbles in microfluidic systems, using the principle of total internal reflection (TIR) is presented. A laser beam impinges on the side walls of a channel which are inclined at 45deg. In an unfilled channel of such a "V-groove", TIR...... deflects the beam by 90deg into a simple light detector. Upon the presence of liquid, the refractive index in the channel changes, thus eliminating deflection by TIR. The detection principle is robust, requiring no calibration, and tolerating alignment errors of the laser larger than the width and depth...

  2. Determination of 3-hydroxypropylmercapturic acid in urine by three column-switching high-performance liquid chromatography with electrochemical detection using a diamond electrode.

    Science.gov (United States)

    Higashi, Kyohei; Shibasaki, Mana; Kuni, Kyoshiro; Uemura, Takeshi; Waragai, Masaaki; Uemura, Kenichi; Igarashi, Kazuei; Toida, Toshihiko

    2017-09-29

    A three column-switching high-performance liquid chromatography (HPLC) using an electrochemical detector (ECD) equipped with a diamond electrode was established to determine 3-hydroxypropylmercapturic acid (3-HPMA) in urine. An extracted urine sample was consecutively fractionated using a strong anion-exchange column (first column) and a C8 column (second column) via a switching valve before application on an Octa Decyl Silyl (ODS) column (third column), followed by ECD analysis. The% recovery of 3-HPMA standard throughout the three-column process and limit of detection (LOD) were 94±1% and 0.1pmol, respectively. A solid phase extraction step is required for the sensitive analysis of 3-HPMA in urine by column-switching HPLC-ECD despite a decreased% recovery (55%) of urine sample spiked with 100pmol of 3-HPMA. To test the utility of our column-switching HPLC-ECD method, 3-HPMA levels of 27 urine samples were determined, and the correlation between HPLC-ECD and LC-Electrospray ionization (ESI)-MS/MS method was examined. As a result, the median values of μmol 3-HPMA/g Creatinine (Cre) in urine obtained by column-switching HPLC-ECD and LC-MS/MS were 2.19±2.12μmol/g Cre and 2.13±3.38μmol/g Cre, respectively, and the calibration curve (y=1.5171x-1.007) exhibited good linearity within a defined range (r 2 =0.907). These results indicate that the combination of column-switching HPLC and ECD is a powerful tool for the specific, reliable detection of 3-HPMA in urine. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Determination of Myo-Inositol in Infant, Pediatric, and Adult Formulas by Liquid Chromatography-Pulsed Amperometric Detection with Column Switching: Collaborative Study, Final Action 2011.18.

    Science.gov (United States)

    Butler-Thompson, Linda D; Jacobs, Wesley A; Schimpf, Karen J

    2015-01-01

    AOAC First Action Method 2011.18, Myo-Inositol (Free and Bound as Phosphatidylinositol) in Infant and Pediatric Formulas and Adult Nutritionals, was collaboratively studied. With this method free myo-inositol and phosphatidylinositol bound myo-inositol are extracted using two different sample preparation procedures, separated by ion chromatography using a combination of Dionex Carbo Pac PA1 and MA1 columns with column switching, and detected with pulsed amperometry using a gold electrode. Free myo-inositol is extracted from samples with dilute hydrochloric acid and water. Phosphatidylinositol is extracted from samples with chloroform and separated from other fats with silica SPE cartridges. Myo-inositol is then released from the glycerol backbone with concentrated acetic and hydrochloric acids at 120°C. During this collaborative study, nine laboratories from five different countries analyzed blind duplicates of nine infant and pediatric nutritional formulas for both free and phosphatidylinositol bound myo-inositol, and one additional laboratory only completed the free myo-inositol analyses. The method demonstrated acceptable repeatability and reproducibility and met the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) Standard Method Performance Requirements (SMPRs®) for free myo-inositol plus phosphatidylinositol bound myo-inositol for all the matrixes analyzed. SMPRs for repeatability were ≤5% RSD at myo-inositol concentrations of 2-68 mg/100 g ready-to-feed (RTF) liquid. SMPRs for reproducibility were ≤8% RSD in products with myo-inositol concentrations ranging from 2 to 68 mg/100 g RTF liquid. During this collaborative study, repeatability RSDs ranged from 0.51 to 3.22%, and RSDs ranged from 2.66 to 7.55% for free myo-inositol plus phosphatidylinositol bound myo-inositol.

  4. Millimeter-scale liquid metal droplet thermal switch

    Science.gov (United States)

    Yang, Tianyu; Kwon, Beomjin; Weisensee, Patricia B.; Kang, Jin Gu; Li, Xuejiao; Braun, Paul; Miljkovic, Nenad; King, William P.

    2018-02-01

    Devices capable of actively controlling heat flow have been desired by the thermal management community for decades. The need for thermal control has become particularly urgent with power densification resulting in devices with localized heat fluxes as high as 1 kW/cm2. Thermal switches, capable of modulating between high and low thermal conductances, enable the partitioning and active control of heat flow pathways. This paper reports a millimeter-scale thermal switch with a switching ratio >70, at heat fluxes near 10 W/cm2. The device consists of a silicone channel filled with a reducing liquid or vapor and an immersed liquid metal Galinstan slug. Galinstan has a relatively high thermal conductivity (≈16.5 W/mK at room temperature), and its position can be manipulated within the fluid channel, using either hydrostatic pressure or electric fields. When Galinstan bridges the hot and cold reservoirs (the "ON" state), heat flows across the channel. When the hot and cold reservoirs are instead filled with the encapsulating liquid or vapor (the "OFF" state), the cross-channel heat flow significantly reduces due to the lower thermal conductivity of the solution (≈0.03-0.6 W/mK). We demonstrate switching ratios as high as 15.6 for liquid filled channels and 71.3 for vapor filled channels. This work provides a framework for the development of millimeter-scale thermal switches and diodes capable of spatial and temporal control of heat flows.

  5. Switching of charged inverse micelles in non-polar liquids.

    Science.gov (United States)

    Prasad, Manoj; Beunis, Filip; Neyts, Kristiaan; Strubbe, Filip

    2015-11-15

    The electrodynamics of micellar ions in nonpolar liquids are well understood for the case that a voltage is applied or switched off. In this work, the electrodynamics of charged inverse micelles (CIMs) are studied when the applied voltage is switched to the opposite polarity, which is relevant for applications such as electrophoretic displays and liquid toner printing. Transient current measurements are used to characterize the switching of CIMs formed in a solution of surfactant polyisobutylene succinimide in n-dodecane. For reverse voltages with amplitude below 10V the measurements are in good agreement with a drift and diffusion model, confirming the established understanding of CIMs in nonpolar liquids. When the charge content is high, the reversal current shows a characteristic peak which is explained on the basis of dynamic space-charge effects. However, for reverse voltages larger than 10V, the transient currents are influenced by electrohydrodynamic flow in the liquid causing the CIMs to switch faster than predicted by the model. The occurrence of electrohydrodynamic flow is verified by optical tracking of tracer particles. Also, when the polarizing voltage is applied for longer times, an additional current peak emerges which is due to the accumulation of newly generated charges at the electrodes. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Electrostatically actuated resonant switches for earthquake detection

    KAUST Repository

    Ramini, Abdallah H.

    2013-04-01

    The modeling and design of electrostatically actuated resonant switches (EARS) for earthquake and seismic applications are presented. The basic concepts are based on operating an electrically actuated resonator close to instability bands of frequency, where it is forced to collapse (pull-in) if operated within these bands. By careful tuning, the resonator can be made to enter the instability zone upon the detection of the earthquake signal, thereby pulling-in as a switch. Such a switching action can be functionalized for useful functionalities, such as shutting off gas pipelines in the case of earthquakes, or can be used to activate a network of sensors for seismic activity recording in health monitoring applications. By placing a resonator on a printed circuit board (PCB) of a natural frequency close to that of the earthquake\\'s frequency, we show significant improvement on the detection limit of the EARS lowering it considerably to less than 60% of the EARS by itself without the PCB. © 2013 IEEE.

  7. Low pull-in voltage electrostatic MEMS switch using liquid dielectric

    KAUST Repository

    Zidan, Mohammed A.

    2014-08-01

    In this paper, we present an electrostatic MEMS switch with liquids as dielectric to reduce the actuation voltage. The concept is verified by simulating a lateral dual gate switch, where the required pull-in voltage is reduced by more than 8 times after using water as a dielectric, to become as low as 5.36V. The proposed switch is simulated using COMSOL multiphysics using various liquid volumes to study their effect on the switching performance. Finally, we propose the usage of the lateral switch as a single switch XOR logic gate.

  8. Silicon Controlled Switch for Detection of Ionizing Radiation

    Science.gov (United States)

    2015-12-01

    7 II. EXPERIMENTAL ANALYSIS OF KEY CIRCUIT ELEMENTS A. SCS STANDALONE I-V OPERATION A Silicon -Controlled Switch (SCS) is a semiconductor...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited SILICON CONTROLLED...Master’s thesis 4. TITLE AND SUBTITLE SILICON CONTROLLED SWITCH FOR DETECTION OF IONIZING RADIATION 5. FUNDING NUMBERS 6. AUTHOR(S) Karl J

  9. Electro-optical switching of liquid crystals of graphene oxide

    Science.gov (United States)

    Song, Jang-Kun

    Electric field effects on aqueous graphene-oxide (GO) dispersions are reviewed in this chapter. In isotropic and biphasic regimes of GO dispersions, in which the inter-particle friction is low, GO particles sensitively respond to the application of electric field, producing field-induced optical birefringence. The electro-optical sensitivity dramatically decreases as the phase transits to the nematic phase; the increasing inter-particle friction hinders the rotational switching of GO particles. The corresponding Kerr coefficient reaches the maximum near the isotropic to biphasic transition concentration, at which the Kerr coefficient is found be c.a. 1:8 · 10-5 mV-2, the highest value ever reported in all Kerr materials. The exceptionally large Kerr effect arises from the Maxwell- Wagner polarization of GO particles with an extremely large aspect ratio and a thick electrical double layer (EDL). The polarization sensitively depends on the ratio of surface and bulk conductivities in dispersions. As a result, low ion concentration in bulk solvent is highly required to achieve a quality electro-optical switching in GO dispersions. Spontaneous vinylogous carboxylic reaction in GO particles produces H+ ions, resulting in spontaneous degradation of electro-optical response with time, hence the removal of residual ions by using a centrifuge cleaning process significantly improves the electro-optical sensitivity. GO particle size is another important parameter for the Kerr coefficient and the response time. The best performance is observed in a GO dispersion with c.a. 0.5 μm mean size. Dielectrophoretic migration of GO particles can be also used to manipulate GO particles in solution. Using these unique features of GO dispersions, one can fabricate GO liquid crystal devices similar to conventional liquid crystal displays; the large Kerr effect allows fabricating a low power device working at extremely low electric fields.

  10. Time resolution research in liquid scintillating detection

    International Nuclear Information System (INIS)

    He Hongkun; Shi Haoshan

    2006-01-01

    The signal processing design method is introduced into liquid scintillating detection system design. By analyzing the signal of liquid scintillating detection, improving time resolution is propitious to upgrade efficiency of detecting. The scheme of realization and satisfactory experiment data is demonstrated. Besides other types of liquid scintillating detection is the same, just using more high speed data signal processing techniques and elements. (authors)

  11. Robust filtering and fault detection of switched delay systems

    CERN Document Server

    Wang, Dong; Wang, Wei

    2013-01-01

    Switched delay systems appear in a wide field of applications including networked control systems, power systems, memristive systems. Though the large amount of ideas with respect to such systems have generated, until now, it still lacks a framework to focus on filter design and fault detection issues which are relevant to life safety and property loss. Beginning with the comprehensive coverage of the new developments in the analysis and control synthesis for switched delay systems, the monograph not only provides a systematic approach to designing the filter and detecting the fault of switched delay systems, but it also covers the model reduction issues. Specific topics covered include: (1) Arbitrary switching signal where delay-independent and delay-dependent conditions are presented by proposing a linearization technique. (2) Average dwell time where a weighted Lyapunov function is come up with dealing with filter design and fault detection issues beside taking model reduction problems. The monograph is in...

  12. Code-switched English pronunciation modeling for Swahili spoken term detection

    CSIR Research Space (South Africa)

    Kleynhans, N

    2016-05-01

    Full Text Available We investigate modeling strategies for English code-switched words as found in a Swahili spoken term detection system. Code switching, where speakers switch language in a conversation, occurs frequently in multilingual environments, and typically...

  13. Supernova Neutrino Detection With Liquid Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Ianni, Aldo, E-mail: aldo.ianni@lngs.infn.it [I.N.F.N. Gran Sasso Laboratory, S.S. 17bis, 67100, Assergi (Italy)

    2011-08-10

    Core collapse supernovae are a remarkable source of neutrinos. These neutrinos can also be detected by means of massive liquid scintillators located underground. Observations of supernova neutrinos can shed light on the explosion mechanism and on neutrino properties. In this paper we review the detection channels for neutrinos in liquid scintillators. We consider present and future experiments for supernova neutrino searches.

  14. Researches on Position Detection for Vacuum Switch Electrode

    Science.gov (United States)

    Dong, Huajun; Guo, Yingjie; Li, Jie; Kong, Yihan

    2018-03-01

    Form and transformation character of vacuum arc is important influencing factor on the vacuum switch performance, and the dynamic separations of electrode is the chief effecting factor on the transformation of vacuum arcs forms. Consequently, how to detect the position of electrode to calculate the separations in the arcs image is of great significance. However, gray level distribution of vacuum arcs image isn’t even, the gray level of burning arcs is high, but the gray level of electrode is low, meanwhile, the forms of vacuum arcs changes sharply, the problems above restrict electrode position detection precisely. In this paper, algorithm of detecting electrode position base on vacuum arcs image was proposed. The digital image processing technology was used in vacuum switch arcs image analysis, the upper edge and lower edge were detected respectively, then linear fitting was done using the result of edge detection, the fitting result was the position of electrode, thus, accurate position detection of electrode was realized. From the experimental results, we can see that: algorithm described in this paper detected upper and lower edge of arcs successfully and the position of electrode was obtained through calculation.

  15. Stereoselective determination of unchanged and glucuroconjugated eliprodil, a new anti-ischaemic drug, in human plasma and urine by precolumn derivatization and column-switching high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Malavasi, B; Ripamonti, M; Rouchouse, A; Ascalone, V

    1996-04-05

    An HPLC method was developed and validated for the determination in human plasma and urine of the enantiomers of eliprodil, (+/-)-alpha-(4-chlorophenyl)-4[(4-fluorophenyl) methyl]piperidine-1-ethanol hydrochloride, a new anti-ischaemic agent administered as a racemate. Both enantiomers are present in human plasma in unchanged and glucuroconjugated form, whereas only the glucuroconjugated form is excreted into urine; as a consequence, such metabolites in human plasma and urine should be submitted to enzymatic deconjugation with beta-glucuronidase (Escherichia coli) before being extracted. The general method involves a liquid-liquid extraction of eliprodil and internal standard from alkalinized plasma or urine with n-hexane, evaporation of the organic phase and derivatization with (S)-(+)-naphthylethyl isocyanate to give carbamate diastereoisomeric derivatives of (S)-(+)- and (R)-(-)-eliprodil and internal standard; after evaporation of the derivatizing mixture and dissolution of the residue in a small volume of phosphate buffer-acetonitrile (60:40, v/v), an aliquot is injected into a column-switching HPLC system. The derivatized sample extract is purified on a precolumn filled with C8-bonded silica material, which is flushed with acetonitrile-water, then diastereoisomers of eliprodil and the internal standard are automatically transferred by the mobile phase to the analytical column. The analytical column is a C8 type, specially deactivated for basic compounds, the mobile phase is 0.025 M phosphate buffer (pH 2.6)-methanol-acetonitrile (42:2:56) at a flow-rate of 1.2 ml min-1 and fluorimetric detector operating at lambda ex = 275 nm and lambda em = 336 nm is used. The retention times, under these conditions, are about 16 and 17 min for (S)-(+)- and (R)-(-)-eliprodil diastereoisomers, respectively, and about 19 min for the first-eluted diastereoisomer of the internal standard. During the analysis time, the precolumn, reset in a different path from that of the

  16. Viewing angle switching of liquid crystal display using fringe-field switching to control off-axis phase retardation

    International Nuclear Information System (INIS)

    Lim, Young Jin; Kim, Jin Ho; Her, Jung Hwa; Lee, Seung Hee; Park, Kyoung Ho; Lee, Joun Ho; Kim, Byeong Koo; Kang, Wan-Seok; Lee, Gi-Dong

    2010-01-01

    A viewing angle switchable liquid crystal display associated with fringe-field switching mode is proposed. In the device, one pixel is composed of a main pixel and a sub-pixel, in which both pixels are formed to generate a fringe electric field. However, the field directions are different from each other so that in the main pixel, the fringe field rotates the liquid crystal for displaying the main image, whereas it controls only the tilt angle of the liquid crystal without rotating in the sub-pixel region. In this way, phase retardation to cause leakage of light at the off-normal axis can be generated in the sub-pixel, and by utilizing the light, the main displayed image in the normal direction can be blocked in the oblique viewing direction.

  17. Viewing angle switching of liquid crystal display using fringe-field switching to control off-axis phase retardation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Young Jin; Kim, Jin Ho; Her, Jung Hwa; Lee, Seung Hee [Polymer BIN Fusion Research Center, Department of Polymer Nano-Science and Technology, Chonbuk National University, Chonju, Chonbuk 561-756 (Korea, Republic of); Park, Kyoung Ho; Lee, Joun Ho; Kim, Byeong Koo [Mobile Product Development Department, LG Display Company, Ltd, Gumi, Gyungbuk 730-350 (Korea, Republic of); Kang, Wan-Seok; Lee, Gi-Dong, E-mail: gdlee@dau.ac.k, E-mail: lsh1@chonbuk.ac.k [Department of Electronics Engineering, Dong-A University, Pusan 604-714 (Korea, Republic of)

    2010-03-03

    A viewing angle switchable liquid crystal display associated with fringe-field switching mode is proposed. In the device, one pixel is composed of a main pixel and a sub-pixel, in which both pixels are formed to generate a fringe electric field. However, the field directions are different from each other so that in the main pixel, the fringe field rotates the liquid crystal for displaying the main image, whereas it controls only the tilt angle of the liquid crystal without rotating in the sub-pixel region. In this way, phase retardation to cause leakage of light at the off-normal axis can be generated in the sub-pixel, and by utilizing the light, the main displayed image in the normal direction can be blocked in the oblique viewing direction.

  18. Rapid leak detection with liquid crystals

    Science.gov (United States)

    Heisman, R. M.; Iceland, W. F.; Ruppe, E. P.

    1978-01-01

    Small leaks in vacuum lines are detected by applying liquid-crystal coating, warming suspected area, and observing color change due to differential cooling by leak jet. Technique is used on inside or outside walls of vacuum-jacketed lines.

  19. Electronic logic to enhance switch reliability in detecting openings and closures of redundant switches

    Science.gov (United States)

    Cooper, James A.

    1986-01-01

    A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and failsafe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.

  20. Technique for detecting liquid metal leaks

    International Nuclear Information System (INIS)

    Bauerle, J.E.

    1979-01-01

    In a system employing flowing liquid metal as a heat transfer medium in contact with tubular members containing a working fluid, i.e., steam, liquid metal leaks through the wall of the tubular member are detected by dislodging the liquid metal compounds forming in the tubular member at the leak locations and subsequently transporting the dislodged compound in the form of an aerosol to a detector responsive to the liquid metal compound. In the application to a sodium cooled tubular member, the detector would consist of a sodium responsive device, such as a sodium ion detector

  1. Method for detecting an open-switch fault in a grid-connected NPC inverter system

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Jeong, Hae-Gwang; Lee, Kyo-Beum

    2012-01-01

    This paper proposes a fault-detection method for an open-switch fault in the switches of grid-connected neutral-point-clamped inverter systems. The proposed method can not only detect the fault condition but also identify the location of the faulty switch. In the proposed method, which is designed...... by incorporating a simple switching control in the conventional method, the fault condition is detected on the basis of the radius of the Concordia current pattern, and the location of the faulty switch can be identified. By using the proposed method, it is possible to detect the open-switch fault and identify...... the faulty switch within two fundamental periods, without using additional sensors or performing complex calculations. Simulations and experiments are carried out to confirm the reliability of the proposed fault-detection method....

  2. Noise Robust Voice Activity Detection Based on Switching Kalman Filter

    Science.gov (United States)

    Fujimoto, Masakiyo; Ishizuka, Kentaro

    This paper addresses the problem of voice activity detection (VAD) in noisy environments. The VAD method proposed in this paper is based on a statistical model approach, and estimates statistical models sequentially without a priori knowledge of noise. Namely, the proposed method constructs a clean speech/silence state transition model beforehand, and sequentially adapts the model to the noisy environment by using a switching Kalman filter when a signal is observed. In this paper, we carried out two evaluations. In the first, we observed that the proposed method significantly outperforms conventional methods as regards voice activity detection accuracy in simulated noise environments. Second, we evaluated the proposed method on a VAD evaluation framework, CENSREC-1-C. The evaluation results revealed that the proposed method significantly outperforms the baseline results of CENSREC-1-C as regards VAD accuracy in real environments. In addition, we confirmed that the proposed method helps to improve the accuracy of concatenated speech recognition in real environments.

  3. chromswitch: A flexible method to detect chromatin state switches.

    Science.gov (United States)

    Jessa, Selin; Kleinman, Claudia L

    2018-02-09

    Chromatin state plays a major role in controlling gene expression, and comparative analysis of ChIP-seq data is key to understanding epigenetic regulation. We present chromswitch, an R/Bioconductor package to integrate epigenomic data in a defined window of interest to detect an overall switch in chromatin state. Chromswitch accurately classifies a benchmarking dataset, and when applied genome-wide, the tool successfully detects chromatin changes that result in brain-specific expression. Chromswitch is implemented as an R package available from Bioconductor at https://bioconductor.org/packages/chromswitch. claudia.kleinman@mcgill.ca. Supplementary material are available online. All data and code for the analysis presented in this paper are available at https://doi.org/10.5281/zenodo.1101260.

  4. Light-driven chiral molecular switches or motors in liquid crystals.

    Science.gov (United States)

    Wang, Yan; Li, Quan

    2012-04-17

    The ability to tune molecular self-organization with an external stimulus is a main driving force in the bottom-up nanofabrication of molecular devices. Light-driven chiral molecular switches or motors in liquid crystals that are capable of self-organizing into optically tunable helical superstructures undoubtedly represent a striking example, owing to their unique property of selective light reflection and which may lead to applications in the future. In this review, we focus on different classes of light-driven chiral molecular switches or motors in liquid crystal media for the induction and manipulation of photoresponsive cholesteric liquid crystal systems and their consequent applications. Moreover, the change of helical twisting powers of chiral dopants and their capability of helix inversion in the induced cholesteric phases are highlighted and discussed in the light of their molecular geometric changes. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Frequency-dependent dielectric contribution of flexoelectricity allowing control of state switching in helicoidal liquid crystals.

    Science.gov (United States)

    Outram, B I; Elston, S J

    2013-07-01

    The contribution of flexoelectric polarization to the dielectric susceptibility in helicoidal liquid crystals is formulated for the static equilibrium case, and further in the case of a time-varying field. A dispersion of the dielectric permittivity due to the frequency response of flexoelectric switching is described. The special case of a negative dielectric-anisotropy nematic material is considered and experimentally shown to agree with the analytical theory. It is further demonstrated how relaxation of the flexoelectric contribution to the dielectric tensor in this special case can be exploited to switch between states in cholesteric liquid crystal structures by altering the applied time-dependent field amplitude, if Δε-Δεε(0). Consequentially, a versatile mechanism for driving between states in liquid crystal systems has been demonstrated and its implications for technology are suggested, and include dual-mode, bistable, and transflective displays.

  6. Frequency-dependent dielectric contribution of flexoelectricity allowing control of state switching in helicoidal liquid crystals

    Science.gov (United States)

    Outram, B. I.; Elston, S. J.

    2013-07-01

    The contribution of flexoelectric polarization to the dielectric susceptibility in helicoidal liquid crystals is formulated for the static equilibrium case, and further in the case of a time-varying field. A dispersion of the dielectric permittivity due to the frequency response of flexoelectric switching is described. The special case of a negative dielectric-anisotropy nematic material is considered and experimentally shown to agree with the analytical theory. It is further demonstrated how relaxation of the flexoelectric contribution to the dielectric tensor in this special case can be exploited to switch between states in cholesteric liquid crystal structures by altering the applied time-dependent field amplitude, if Δɛ-Δɛɛ0. Consequentially, a versatile mechanism for driving between states in liquid crystal systems has been demonstrated and its implications for technology are suggested, and include dual-mode, bistable, and transflective displays.

  7. Apparatus for detecting leakage of liquid sodium

    Science.gov (United States)

    Himeno, Yoshiaki

    1978-01-01

    An apparatus for detecting the leakage of liquid sodium includes a cable-like sensor adapted to be secured to a wall of piping or other equipment having sodium on the opposite side of the wall, and the sensor includes a core wire electrically connected to the wall through a leak current detector and a power source. An accidental leakage of the liquid sodium causes the corrosion of a metallic layer and an insulative layer of the sensor by products resulted from a reaction of sodium with water or oxygen in the atmospheric air so as to decrease the resistance between the core wire and the wall. Thus, the leakage is detected as an increase in the leaking electrical current. The apparatus is especially adapted for use in detecting the leakage of liquid sodium from sodium-conveying pipes or equipment in a fast breeder reactor.

  8. Voltage-Controlled Switching of Strong Light-Matter Interactions using Liquid Crystals.

    Science.gov (United States)

    Hertzog, Manuel; Rudquist, Per; Hutchison, James A; George, Jino; Ebbesen, Thomas W; Börjesson, Karl

    2017-12-22

    We experimentally demonstrate a fine control over the coupling strength of vibrational light-matter hybrid states by controlling the orientation of a nematic liquid crystal. Through an external voltage, the liquid crystal is seamlessly switched between two orthogonal directions. Using these features, for the first time, we demonstrate electrical switching and increased Rabi splitting through transition dipole moment alignment. The C-N str vibration on the liquid crystal molecule is coupled to a cavity mode, and FT-IR is used to probe the formed vibropolaritonic states. A switching ratio of the Rabi splitting of 1.78 is demonstrated between the parallel and the perpendicular orientation. Furthermore, the orientational order increases the Rabi splitting by 41 % as compared to an isotropic liquid. Finally, by examining the influence of molecular alignment on the Rabi splitting, the scalar product used in theoretical modeling between light and matter in the strong coupling regime is verified. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Redox-switched amphiphilic ionic liquid behavior in aqueous solution.

    Science.gov (United States)

    Chamiot, Bénédicte; Rizzi, Cécile; Gaillon, Laurent; Sirieix-Plénet, Juliette; Lelièvre, Joël

    2009-02-03

    A new redox amphiphilic ionic liquid (AIL) containing ferrocene as a redox-active group was synthesized, 1-(11-ferrocenylundecyl)-3-methylimidazolium bromide (Fc11MIm+). Adsorption and aggregation of both reduced and oxidized forms of this ferrocenated AIL in aqueous solution were studied by surface tension measurements. The micellization was favored for the reduced ferrocenated AIL (Fc11MIm+) as compared with the oxidized ferrocenated AIL (Fc+11MIm+). Minimum areas at the air/aqueous solution interface were identical whereas limiting surface tensions were slightly different. This corroborated the formation of an expanded monolayer of redox active AIL at the interface. The electrochemical behavior of redox active AIL was investigated. The electrochemical responses of Fc11MIm+ aqueous solution interestingly differed, depending on its concentration. Below the cmc, the electrochemical reaction was dominated by ferrocenated AIL adsorbed onto the electrode surface; then above the cmc, it was controlled by the Fc11MIm+ diffusing to the electrode. For the latter, the electrochemical mechanism was suggested to couple with the disruption reaction of the reduced form micelles.

  10. Lidar Electro-Optic Beam Switch with a Liquid Crystal Variable Retarder

    Science.gov (United States)

    Baer, James

    2012-01-01

    A document discusses a liquid crystal variable retarder, an electro-optic element that changes the polarization of an optical beam in response to a low-voltage electronic signal. This device can be fabricated so that the element creates, among other states, a half-wave of retardance that can be reduced to a very small retardance. When aligned to a polarized source, this can act to rotate the polarization by 90 in one state, but generate no rotation in the other state. If the beam is then incident on a polarization beam splitter, it will efficiently switch from one path to the other when the voltage is applied. The laser beam switching system has no moving parts, improving reliability over mechanical switching. It is low cost, tolerant of high laser power density, and needs only simple drive electronics, minimizing the required system resources.

  11. Time-resolved sign-dependent switching in a hybrid aligned nematic liquid crystal cell

    International Nuclear Information System (INIS)

    Taphouse, T S; Cornford, S L; Birkett, J E; Sambles, J R

    2008-01-01

    An optical waveguide technique is used to determine the director tilt profile across a hybrid aligned nematic (HAN) liquid crystal cell, in which the optical response is dependent on the sign of the applied voltage. Two physical models are shown that fit the equilibrium experimental data, but with alternative explanations for this sign dependence. Models with either a flexoelectric coefficient of 2.25x10 -11 C m -1 or a bound surface charge of 12.2 μC m -2 are shown that fit this equilibrium data. In an attempt to resolve this degeneracy sign-dependent switching data are analysed. However, neither model can explain these switching data, which are affected by slow transients of ∼100 ms which are believed to be due to the motion of free ions in the liquid crystal. From the form of these slow transients, it is suggested that the equilibrium position of the ions is next to a cell substrate

  12. Code-switched English Pronunciation Modeling for Swahili Spoken Term Detection (Pub Version, Open Access)

    Science.gov (United States)

    2016-05-03

    resourced Languages, SLTU 2016, 9-12 May 2016, Yogyakarta, Indonesia Code-switched English Pronunciation Modeling for Swahili Spoken Term Detection Neil...Abstract We investigate modeling strategies for English code-switched words as found in a Swahili spoken term detection system. Code switching...et al. / Procedia Computer Science 81 ( 2016 ) 128 – 135 Our research focuses on pronunciation modeling of English (embedded language) words within

  13. Liquid chromatography detection unit, system, and method

    Science.gov (United States)

    Derenzo, Stephen E.; Moses, William W.

    2015-10-27

    An embodiment of a liquid chromatography detection unit includes a fluid channel and a radiation detector. The radiation detector is operable to image a distribution of a radiolabeled compound as the distribution travels along the fluid channel. An embodiment of a liquid chromatography system includes an injector, a separation column, and a radiation detector. The injector is operable to inject a sample that includes a radiolabeled compound into a solvent stream. The position sensitive radiation detector is operable to image a distribution of the radiolabeled compound as the distribution travels along a fluid channel. An embodiment of a method of liquid chromatography includes injecting a sample that comprises radiolabeled compounds into a solvent. The radiolabeled compounds are then separated. A position sensitive radiation detector is employed to image distributions of the radiolabeled compounds as the radiolabeled compounds travel along a fluid channel.

  14. PET/MR Synchronization by Detection of Switching Gradients

    Science.gov (United States)

    Weissler, Bjoern; Gebhardt, Pierre; Lerche, Christoph W.; Soultanidis, Georgios M.; Wehner, Jakob; Heberling, Dirk; Schulz, Volkmar

    2015-06-01

    The full potential of simultaneous Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) acquisition, such as dynamic studies or motion compensation, can only be explored if the data of both modalities is temporally synchronized. As such hybrid imaging systems are commonly realized as custom-made PET inserts for commercially available MRI scanner, a synchronization solution has to be implemented (depending on the vendor of the MRI system). In contrast, we demonstrate a simple method for temporal synchronization, which does not require a connection to the MRI. It uses the normally undesired effect of induced voltages on the PET electronics from switching MRI gradients. The electronic circuit needs very few components and the gradient pick-up coils are made from PCB traces and vias on the PET detector boards. Neither programming the MRI nor any physical connection to the MR scanner is needed, thus avoiding electromagnetic compatibility problems. This method works inherently with most MRI sequences and is a vendor- independent solution. A characterization of the sensors in an MRI scanner showed that the MRI gradients are detected with a precision of 120 μs (with the current implementation). Using different trigger thresholds, it is possible to trigger selectively on certain MRI sequences, depending on their gradient slew rate settings. Timings and pulse diagrams of MRI sequences can be recognized from the generated data. The method was successfully used for temporal alignment between PET and MRI in an MRI-based PET-motion-compensation application.

  15. Open-switch fault detection method of an NPC converter for wind turbine systems

    DEFF Research Database (Denmark)

    Lee, June-Seok; Lee, Kyo-Beum; Blaabjerg, Frede

    2013-01-01

    In wind turbine generation (WTG) systems, the neutral-point-clamped (NPC) topology is widely used as the part of a back-to-back converter since the three-level NPC topology has more advantages than the conventional two-level inverter especially for high power. There are twelve switches in the NPC...... topology and an open-switch fault of the NPC converter leads to current distortion and the torque ripple in the system. Furthermore, WTG systems can breakdown in the worst case by this ripple. To improve the reliability of WTG systems, an open-switch fault detection method is required. The open......-switch detection method of the NPC converter is different from that of the NPC inverter due to the different current paths of the NPC converter. This paper proposes the open-switch fault detection method of the NPC converter connected the permanent-magnet synchronous generator (PMSG). Moreover, the open...

  16. Liquid-Xe detector for contraband detection

    International Nuclear Information System (INIS)

    Vartsky, D.; Israelashvili, I.; Cortesi, M.; Arazi, L.; Coimbra, A.E.; Moleri, L.; Erdal, E.; Bar, D.; Rappaport, M.; Shchemelinin, S.; Caspi, E.N.; Aviv, O.; Breskin, A.

    2016-01-01

    We describe progress made with a liquid-Xe (LXe) detector coupled to a gaseous photomultiplier (GPM), for combined imaging and spectroscopy of fast neutrons and gamma-rays in the MeV range. The purpose of this detector is to enable the detection of hidden explosives and fissile materials in cargo and containers. The expected position resolution is about 2 m and 3.5 mm for fast neutrons and gamma-rays, respectively. Experimental results obtained using an 241 Am source yielded energy and time resolutions of 11% and 1.2 ns RMS, respectively. Initial results obtained with the position-sensitive GPM are presented.

  17. Liquid-Xe detector for contraband detection

    Energy Technology Data Exchange (ETDEWEB)

    Vartsky, D., E-mail: david.vartsky@weizmann.ac.il [Weizmann Institute of Science, Rehovot 76100 (Israel); Israelashvili, I. [Weizmann Institute of Science, Rehovot 76100 (Israel); Nuclear Research Center of Negev (NRCN), Beer-Sheva 9001 (Israel); Cortesi, M. [National Superconducting Cyclotron Laboratory, East Lansing 48823, MI (United States); Arazi, L.; Coimbra, A.E.; Moleri, L.; Erdal, E.; Bar, D.; Rappaport, M.; Shchemelinin, S. [Weizmann Institute of Science, Rehovot 76100 (Israel); Caspi, E.N. [Nuclear Research Center of Negev (NRCN), Beer-Sheva 9001 (Israel); Aviv, O. [Soreq NRC, Yavne 81800 (Israel); Breskin, A. [Weizmann Institute of Science, Rehovot 76100 (Israel)

    2016-07-11

    We describe progress made with a liquid-Xe (LXe) detector coupled to a gaseous photomultiplier (GPM), for combined imaging and spectroscopy of fast neutrons and gamma-rays in the MeV range. The purpose of this detector is to enable the detection of hidden explosives and fissile materials in cargo and containers. The expected position resolution is about 2 m and 3.5 mm for fast neutrons and gamma-rays, respectively. Experimental results obtained using an {sup 241}Am source yielded energy and time resolutions of 11% and 1.2 ns RMS, respectively. Initial results obtained with the position-sensitive GPM are presented.

  18. Liquid-scintillation alpha-detection techniques

    International Nuclear Information System (INIS)

    McKlveen, J.W.; McDowell, W.J.

    1983-01-01

    Accurate, quantitative determinations of alpha-emitting nuclides by conventional plate-counting methods are difficult because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillation counting medium. Detection electronics use energy and pulse-shape discrimination to yield alpha spectra without beta and gamma background interference. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. Possibilities for a large number of other applications exist. Accuracy and reproducibility are typically in the 1% range. Backgrounds on the order of 0.01 cpm are readily achievable. The paper will present an overview of liquid scintillation alpha counting techniques and some of the results achieved for specific applications

  19. Influence of ZnO nanostructures in liquid crystal interfaces for bistable switching applications

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Kaushik, E-mail: kaushikpal@whu.edu.cn [School of Power and Mechanical Engineering, Wuhan University, 8 East Lake South Road, Wuhan 430072 (China); Zhan, Bihong, E-mail: bihong_zhan@whu.edu.cn [School of Power and Mechanical Engineering, Wuhan University, 8 East Lake South Road, Wuhan 430072 (China); Madhu Mohan, M.L.N. [Liquid Crystal Research Laboratory (LCRL), Bannari Amman Institute of Technology, Sathyamangalam 638 401 (India); Schirhagl, Romana [University Medical Center Groningen, Department of BioMedical Engineering, Ant. Deusinglaan 1, 9713 AV Groningen (Netherlands); Wang, Guoping, E-mail: guopingwang@whu.edu.cn [School of Power and Mechanical Engineering, Wuhan University, 8 East Lake South Road, Wuhan 430072 (China)

    2015-12-01

    Graphical abstract: - Highlights: • One step bench top novel synthesis and growth dynamics of ZnO structures are successfully performed. • Nanostructures dispersing liquid crystals (NDLC) is recently found to have significant influence on the nucleation and growth of many functional nanocrystals (NCs), and provide a fundamental approach to modify the crystallographic phase, size, morphology, and electronic configuration of nanomaterials. • Electro-optical switching application ensures the bright field droplet design marble pattern of smectic G phase, nematic and most significant twist nematic phase pattern are obtained. • Spontaneous polarization, rotational viscosity and response time study, exploring smart applications in LCD technology. - Abstract: The controlled fabrication of nanometer-scale objects is without doubt one of the central issues in current science and technology. In this article, we exhibit a simple, one-step bench top synthesis of zinc oxide nano-tetrapods and nano-spheres which were tailored by the facial growth of nano-wires (diameter ≈ 24 nm; length ≈ 118 nm) and nano-cubes (≈395 nm edge) to nano-sphere (diameter ≈ 585 nm) appeaded. The possibilities of inexpensive, simple solvo-chemical synthesis of nanostructures were considered. In this article, a successful attempt has been made that ZnO nano-structures dispersed on well aligned hydrogen bonded liquid crystals (HBLC) comprising azelaic acid (AC) with p-n-alkyloxy benzoic acid (nBAO) by varying the respective alkyloxy carbon number (n = 5). The dispersion of nanomaterials with HBLC is an effective route to enhance the existing functionalities. A series of these composite materials were analyzed by polarizing optical microscope's electro-optical switching. An interesting feature of AC + nBAO is the inducement of tilted smectic G phase with increasing carbon chain length. Phase diagrams of the above hybrid ZnO nanomaterial influenced LC complex and pure LC were

  20. Localised polymer networks in chiral nematic liquid crystals for high speed photonic switching

    International Nuclear Information System (INIS)

    Tartan, Chloe C.; Salter, Patrick S.; Booth, Martin J.; Morris, Stephen M.; Elston, Steve J.

    2016-01-01

    Self-assembled periodic structures based upon chiral liquid crystalline materials have significant potential in the field of photonics ranging from fast-switching optoelectronic devices to low-threshold lasers. The flexoelectro-optic effect, which is observed in chiral nematic liquid crystals (LCs) when an electric field is applied perpendicular to the helical axis, has significant potential as it exhibits analogue switching in 10–100 μs. However, the major technological barrier that prohibits the commercial realisation of this electro-optic effect is the requirement of a uniform, in-plane alignment of the helix axis between glass substrates. Here, it is shown that periodic polymer structures engineered in the nematic phase of a chiral nematic LC device using direct laser writing can result in the spontaneous formation of the necessary uniform lying helix (ULH) state. Specifically, two-photon polymerization is used in conjunction with a spatial light modulator so as to correct for aberrations introduced by the bounding glass substrates enabling the polymer structures to be fabricated directly into the device. The ULH state appears to be stable in the absence of an externally applied electric field, and the optimum contrast between the bright and dark states is obtained using polymer structures that have periodicities of the order of the device thickness.

  1. Localised polymer networks in chiral nematic liquid crystals for high speed photonic switching

    Energy Technology Data Exchange (ETDEWEB)

    Tartan, Chloe C., E-mail: chloe.tartan@eng.ox.ac.uk, E-mail: steve.elston@eng.ox.ac.uk; Salter, Patrick S.; Booth, Martin J.; Morris, Stephen M.; Elston, Steve J., E-mail: chloe.tartan@eng.ox.ac.uk, E-mail: steve.elston@eng.ox.ac.uk [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom)

    2016-05-14

    Self-assembled periodic structures based upon chiral liquid crystalline materials have significant potential in the field of photonics ranging from fast-switching optoelectronic devices to low-threshold lasers. The flexoelectro-optic effect, which is observed in chiral nematic liquid crystals (LCs) when an electric field is applied perpendicular to the helical axis, has significant potential as it exhibits analogue switching in 10–100 μs. However, the major technological barrier that prohibits the commercial realisation of this electro-optic effect is the requirement of a uniform, in-plane alignment of the helix axis between glass substrates. Here, it is shown that periodic polymer structures engineered in the nematic phase of a chiral nematic LC device using direct laser writing can result in the spontaneous formation of the necessary uniform lying helix (ULH) state. Specifically, two-photon polymerization is used in conjunction with a spatial light modulator so as to correct for aberrations introduced by the bounding glass substrates enabling the polymer structures to be fabricated directly into the device. The ULH state appears to be stable in the absence of an externally applied electric field, and the optimum contrast between the bright and dark states is obtained using polymer structures that have periodicities of the order of the device thickness.

  2. Electrothermally Driven Fluorescence Switching by Liquid Crystal Elastomers Based On Dimensional Photonic Crystals.

    Science.gov (United States)

    Lin, Changxu; Jiang, Yin; Tao, Cheng-An; Yin, Xianpeng; Lan, Yue; Wang, Chen; Wang, Shiqiang; Liu, Xiangyang; Li, Guangtao

    2017-04-05

    In this article, the fabrication of an active organic-inorganic one-dimensional photonic crystal structure to offer electrothermal fluorescence switching is described. The film is obtained by spin-coating of liquid crystal elastomers (LCEs) and TiO 2 nanoparticles alternatively. By utilizing the property of LCEs that can change their size and shape reversibly under external thermal stimulations, the λ max of the photonic band gap of these films is tuned by voltage through electrothermal conversion. The shifted photonic band gap further changes the matching degree between the photonic band gap of the film and the emission spectrum of organic dye mounting on the film. With rhodamine B as an example, the enhancement factor of its fluorescence emission is controlled by varying the matching degree. Thus, the fluorescence intensity is actively switched by voltage applied on the system, in a fast, adjustable, and reversible manner. The control chain of using the electrothermal stimulus to adjust fluorescence intensity via controlling the photonic band gap is proved by a scanning electron microscope (SEM) and UV-vis reflectance. This mechanism also corresponded to the results from the finite-difference time-domain (FDTD) simulation. The comprehensive usage of photonic crystals and liquid crystal elastomers opened a new possibility for active optical devices.

  3. Biofluid-Based Detection of the Migration Switch in Prostate Cancer to Predict Metastatic Disease

    Science.gov (United States)

    2016-09-01

    AWARD NUMBER: W81XWH-15-1-0416 TITLE: Biofluid-Based Detection of the Migration Switch in Prostate Cancer to Predict Metastatic Disease PRINCIPAL...Aug 2016 Sep.20164. TITLE AND SUBTITLE Biofluid-Based Detection of the Migration Switch in Prostate Cancer to Predict Metastatic Disease 5a...accurately and non-invasively monitor localized disease longitudinally will allow patients to avoid the side effects and morbidity of definitive treatment

  4. Recent advances in fast-switching liquid-crystal mode based on uniform lying helix (ULH) (Conference Presentation)

    Science.gov (United States)

    Wittek, Michael; Siemianowski, Simon; Fiebranz, Bernd; Klasen-Memmer, Melanie

    2017-02-01

    Uniform lying Helix (ULH) is one of the most promising new LC modes for fast switching applications with alternative driving schemes such as FSC (field sequential colour). ULH operates via flexoelectric switching, unlike current commercially available liquid crystal modes that operate via dielectric switching. The realisation of mixtures with suitable flexoelectric properties requires unique materials composed of specially designed ´bi-mesogenś and also the addition of a chiral dopant. Recent advances, updated mixture performance and other challenges such as alignment and driving for this new mode are discussed.

  5. Fault detection for discrete-time switched systems with sensor stuck faults and servo inputs.

    Science.gov (United States)

    Zhong, Guang-Xin; Yang, Guang-Hong

    2015-09-01

    This paper addresses the fault detection problem of switched systems with servo inputs and sensor stuck faults. The attention is focused on designing a switching law and its associated fault detection filters (FDFs). The proposed switching law uses only the current states of FDFs, which guarantees the residuals are sensitive to the servo inputs with known frequency ranges in faulty cases and robust against them in fault-free case. Thus, the arbitrarily small sensor stuck faults, including outage faults can be detected in finite-frequency domain. The levels of sensitivity and robustness are measured in terms of the finite-frequency H- index and l2-gain. Finally, the switching law and FDFs are obtained by the solution of a convex optimization problem. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  6. A column switching ultrahigh-performance liquid chromatography-tandem mass spectrometry method to determine anandamide and 2-arachidonoylglycerol in plasma samples.

    Science.gov (United States)

    Marchioni, Camila; de Souza, Israel Donizeti; Grecco, Caroline Fernandes; Crippa, José Alexandre; Tumas, Vitor; Queiroz, Maria Eugênia Costa

    2017-05-01

    This study reports a fast, sensitive, and selective column switching ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to determine the endocannabinoids (eCBs), anandamide (AEA), and 2-arachidonoylglycerol (2-AG) in plasma samples. This bidimensional system used a restricted access media column (RP-8 ADS, 25 mm × 4 mm × 25 μM) in the first dimension and a core-shell Kinetex C18 (100 mm × 2, 1.7 mm × 1 μM) column in the second dimension, followed by detection in a mass spectrometer triple quadrupole (multiple reactions monitoring mode) operating in the positive mode. RP-8 ADS was used for trace enrichment of eCBs (reverse phase partitioning) and macromolecular matrix size exclusion; the core-shell column was used for the chromatographic separation. The column switching UHPLC-MS/MS method presented a linear range spanning from 0.1 ng mL -1 (LOQ) to 6 ng mL -1 for AEA and from 0.04 ng mL -1 (LOQ) to 10 ng mL -1 for 2-AG. Excluding the LLOQ values, the precision assays provided coefficients of variation lower than 8% and accuracy with relative standard error values lower than 14%. Neither carryover nor matrix effects were detected. This high-throughput column switching method compared to conventional methods is time saving as it involves fewer steps, consumes less solvent, and presents lower LLOQ. The column switching UHPLC-MS/MS method was successfully applied to determine AEA and 2-AG in plasma samples obtained from Alzheimer's disease patients. Graphical abstract A column switching ultra high-performance liquid chromatography-tandem mass spectrometry method using RP-8 ADS column and core shell column to determine endocannabinoids in plasma samples.

  7. Detection of Hazardous Liquids Using Microwaves

    Science.gov (United States)

    Janezic, Michael D; Splett, Jolene D; Coakley, Kevin J

    2014-01-01

    We investigate the feasibility of using dielectric spectra to classify hazardous and nonhazardous liquids. The dielectric spectra of several liquids was obtained with a shielded-open coaxial fixture, and we present a new full-wave model for calculating the complex permittivity of liquids using this fixture. Using the measured complex permittivity for each liquid, we examine several classification methods for distinguishing between the hazardous and nonhazardous liquids and report on the error rates of each method. PMID:26601031

  8. Unsupervised Anomaly Detection for Liquid-Fueled Rocket Prop...

    Data.gov (United States)

    National Aeronautics and Space Administration — Title: Unsupervised Anomaly Detection for Liquid-Fueled Rocket Propulsion Health Monitoring. Abstract: This article describes the results of applying four...

  9. Voltage-controlled optical switch in planar nematic liquid crystal film

    Science.gov (United States)

    Shih, Chia-Chi; Chen, Yu-Jen; Wu, Sean; Tsai, Cheng-Che; Jiang, I.-Min

    2009-10-01

    This study presents an integrated device that consists of a directional coupler and an electro-optic switch. The device is designed to include a nematic liquid crystal cell, comprising a grating-like electrode. Applying the appropriate voltage to the cell yields a periodically distributed refractive index. An incident polarized beam will couple to an adjacent channel if it is parallel to the channel. The coupling efficiency is controlled by applied voltage. An obliquely injected polarized beam will be reflected and refracted in the channel, and propagated along a curved path. The route of the beam can be controlled by applying the voltage. A multiport routing was achieved for voltage modulation. In addition, the distribution of refractive index is also investigated by employing conoscopic technique experimentally and numerically.

  10. Optothermal Switching of Cholesteric Liquid Crystals: A Study of Azobenzene Derivatives and Laser Wavelengths

    Directory of Open Access Journals (Sweden)

    Tai-Chieh Huang

    2015-09-01

    Full Text Available The laser-initiated thermal (optothermal switching of cholesteric liquid crystals (CLCs is characterized by using different azobenzene (Azo derivatives and laser wavelengths. Under 405-nm laser irradiation, Azo-doped CLCs undergo phase transition from cholesteric to isotropic. No cis-to-trans photoisomerization occurs when the 405-nm laser irradiation is blocked because only a single laser is used. The fast response of Azo-doped CLCs under the on–off switching of the 405-nm laser occurs because of the optothermal effect of the system. The 660-nm laser, which cannot be used as irradiation to generate the trans–cis photoisomerization of Azo, is used in Anthraquinone (AQ-Azo-doped CLCs to examine the optothermal effect of doped Azo. The results show that the LC-like Azo derivative bearing two methyl groups ortho to the Azo moiety (A4 can greatly lower the clearing temperature and generate large amount of heat in AQ-A4-doped CLCs.

  11. Fundamental studies on the switching in liquid nitrogen environment using vacuum switches for application in future high-temperature superconducting medium-voltage power grids

    International Nuclear Information System (INIS)

    Golde, Karsten

    2016-01-01

    By means of superconducting equipment it is possible to reduce the transmission losses in distribution networks while increasing the transmission capacity. As a result even saving a superimposed voltage level would be possible, which can put higher investment costs compared to conventional equipment into perspective. For operation of superconducting systems it is necessary to integrate all equipment in the cooling circuit. This also includes switchgears. Due to cooling with liquid nitrogen, however, only vacuum switching technology comes into question. Thus, the suitability of vacuum switches is investigated in this work. For this purpose the mechanics of the interrupters is considered first. Material investigations and switching experiments at ambient temperature and in liquid nitrogen supply information on potential issues. For this purpose, a special pneumatic construction is designed, which allows tens of thousands of switching cycles. Furthermore, the electrical resistance of the interrupters is considered. Since the contact system consists almost exclusively of copper, a remaining residual resistance and appropriate thermal losses must be considered. Since they have to be cooled back, an appropriate evaluation is given taking environmental parameters into account. The dielectric strength of vacuum interrupters is considered both at ambient temperature as well as directly in liquid nitrogen. For this purpose different contact distances are set at different interrupter types. A distinction is made between internal and external dielectric strength. Conditioning and deconditioning effects are minimized by an appropriate choice of the test circuit. The current chopping and resulting overvoltages are considered to be one of the few drawbacks of vacuum switching technology. Using a practical test circuit the height of chopping current is determined and compared for different temperatures. Due to strong scattering the evaluation is done using statistical methods. At

  12. Snapshot Mueller matrix polarimetry by wavelength polarization coding and application to the study of switching dynamics in a ferroelectric liquid crystal cell.

    Directory of Open Access Journals (Sweden)

    Le Jeune B.

    2010-06-01

    Full Text Available This paper describes a snapshot Mueller matrix polarimeter by wavelength polarization coding. This device is aimed at encoding polarization states in the spectral domain through use of a broadband source and high-order retarders. This allows one to measure a full Mueller matrix from a single spectrum whose acquisition time only depends on the detection system aperture. The theoretical fundamentals of this technique are developed prior to validation by experiments. The setup calibration is described as well as optimization and stabilization procedures. Then, it is used to study, by time-resolved Mueller matrix polarimetry, the switching dynamics in a ferroelectric liquid crystal cell.

  13. The Antemortem Detection and Conformational Switches of Prion Proteins

    Science.gov (United States)

    2006-07-01

    PrPsc to detect individual cells that contain PrPsc . Sensitivity studies suggest that it can detect as low as 10 prion-infected cells in 5 x 105 WBCs...The amyloidogenic PrPSc is the only proven surrogate marker for the diagnosis of prion diseases. Therefore almost all of the efforts for diagnosing...prion diseases are directed at detecting PrPsc . Since the only difference between the normal cellular PrPc and the pathological PrPsc is their

  14. Bulk chirality effect for symmetric bistable switching of liquid crystals on topologically self-patterned degenerate anchoring surface.

    Science.gov (United States)

    Park, Min-Kyu; Joo, Kyung-Il; Kim, Hak-Rin

    2017-06-26

    We demonstrate a bistable switching liquid crystal (LC) mode utilizing a topologically self-structured dual-groove surface for degenerated easy axes of LC anchoring. In our study, the effect of the bulk elastic distortion of the LC directors on the bistable anchoring surface is theoretically analyzed for balanced bistable states based on a free energy diagram. By adjusting bulk LC chirality, we developed ideally symmetric and stable bistable anchoring and switching properties, which can be driven by a low in-plane pulsed field of about 0.7 V/µm. The fabricated device has a contrast ratio of 196:1.

  15. Detection of gas entrainment into liquid metals

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, T., E-mail: t.vogt@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, 01328 Dresden (Germany); Boden, S. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, 01328 Dresden (Germany); Andruszkiewicz, A. [Faculty of Mechanical and Power Engineering, Wroclaw University of Technology (Poland); Eckert, K. [Technische Universität Dresden, Institute of Fluid Mechanics, 01062 Dresden (Germany); Eckert, S.; Gerbeth, G. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, 01328 Dresden (Germany)

    2015-12-01

    Highlights: • We present liquid metal experiments dedicated to gas entrainment on the free surface. • Ultrasonic and X-ray attenuation techniques have been used to study the mechanisms of gas entrainment. • A comparison between bubbly flow in water and GaInSn showed substantial differences. • Our results emphasize the importance of liquid metal experiments which are able to provide a suitable data base for numerical code validation. - Abstract: Entrainment of cover gas into the liquid metal coolant is one of the principal safety issues in the design of innovative liquid metal-cooled fast reactors. We present generic experimental studies of this phenomenon in low-melting metals. Ultrasonic and X-ray diagnostic tools were considered for a visualization of gas entrainment at the free surface of the melt. Laboratory experiments were conducted using the eutectic alloy GaInSn, which is liquid at room temperature. Vortex-activated entrainment of air at the free surface of a rotating flow was revealed by ultrasonic techniques. X-ray radioscopy was used to visualize the behavior of argon bubbles inside a slit geometry. The measurements reveal distinct differences between water and GaInSn, especially with respect to the process of bubble formation and the coalescence and breakup of bubbles. Our results emphasize the importance of liquid metal experiments which are able to provide a suitable data base for numerical code validation.

  16. Liquid-helium scintillation detection with germanium photodiodes

    International Nuclear Information System (INIS)

    Luke, P.N.; Haller, E.E.; Steiner, H.M.

    1982-05-01

    Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV α particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes

  17. Bio-recognition and detection using liquid crystals.

    Science.gov (United States)

    Hussain, A; Pina, A S; Roque, A C A

    2009-09-15

    Liquid crystals (LCs) are used extensively by the electronics industry as display devices. Advances in the understanding of the liquid crystalline phase and the chemistry therein lead to the development of LC exhibiting faster switching speed with greater twist angle. This in turn lead to the emergence of liquid crystal displays, rendering dial-and-needle based displays (such as those used in various meters) and cathode ray tubes obsolete. In this article, we review the history of LC and their emergence as an invaluable material for display devices and the more recent discovery of their use as sensing elements in biosensors. This new application of LC as tools in the development of fast and simple biosensors is envisaged to gain more importance in the foreseeable future.

  18. Internal Corrosion Detection in Liquids Pipelines

    Science.gov (United States)

    2012-01-01

    PHMSA project DTRS56-05-T-0005 "Development of ICDA for Liquid Petroleum Pipelines" led to the development of a Direct Assessment (DA) protocol to prioritize locations of possible internal corrosion. The underlying basis LP-ICDA is simple; corrosion ...

  19. Switching Kalman filter based methods for apnea bradycardia detection from ECG signals.

    Science.gov (United States)

    Montazeri Ghahjaverestan, Nasim; Shamsollahi, Mohammad B; Ge, Di; Hernández, Alfredo I

    2015-09-01

    Apnea bradycardia (AB) is an outcome of apnea occurrence in preterm infants and is an observable phenomenon in cardiovascular signals. Early detection of apnea in infants under monitoring is a critical challenge for the early intervention of nurses. In this paper, we introduce two switching Kalman filter (SKF) based methods for AB detection using electrocardiogram (ECG) signal.The first SKF model uses McSharry's ECG dynamical model integrated in two Kalman filter (KF) models trained for normal and AB intervals. Whereas the second SKF model is established by using only the RR sequence extracted from ECG and two AR models to be fitted in normal and AB intervals. In both SKF approaches, a discrete state variable called a switch is considered that chooses one of the models (corresponding to normal and AB) during the inference phase. According to the probability of each model indicated by this switch, the model with larger probability determines the observation label at each time instant.It is shown that the method based on ECG dynamical model can be effectively used for AB detection. The detection performance is evaluated by comparing statistical metrics and the amount of time taken to detect AB compared with the annotated onset. The results demonstrate the superiority of this method, with sensitivity and specificity 94.74[Formula: see text] and 94.17[Formula: see text], respectively. The presented approaches may therefore serve as an effective algorithm for monitoring neonates suffering from AB.

  20. Liquid Photonic Crystals for Mesopore Detection.

    Science.gov (United States)

    Zhu, Biting; Fu, Qianqian; Chen, Ke; Ge, Jianping

    2018-01-02

    Nitrogen adsorption-desorption for mesopore characterization requires the using of expensive instrumentation, time-consuming processes, and the consumption of liquid nitrogen. Herein, a new method is developed to measure the pore parameters through mixing a mesoporous substance with a supersaturated SiO 2 colloidal solution at different temperatures, and subsequent rapid measurement of reflection changes of the precipitated liquid photonic crystals. The pore volumes and diameters of mesoporous silica were measured according to the positive correlation between unit mass reflection change (Δλ/m) and pore volume (V), and the negative correlation between average absorption temperature (T) and pore diameter (D). This new approach may provide an alternative method for fast, convenient and economical characterization of mesoporous materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Simultaneous Determination of 14 Phenolic Compounds in Grape Canes by HPLC-DAD-UV Using Wavelength Switching Detection

    Directory of Open Access Journals (Sweden)

    Ang Zhang

    2013-11-01

    Full Text Available The paper described a novel chromatographic method for the simultaneous determination of phenolic compounds such as gallic, protocatechuic, vanillic, caffeic, syringic, p-coumaric and salicylic acid, (+-catechin, (‒-epicatechin, rutin, morin, quercetin, coumarin and trans-resveratrol at their maximum absorbance wavelengths (MAW employing reverse-phase high performance liquid chromatography combined with DAD and UV detection via detection wavelength switching. The method was based on MAW acquisition by DAD and quantification by UV. The separation process was performed on a Shim-Pack VP-ODS C18 column (250 mm × 4.6 mm, 5 μm held at 30 °C, utilizing 3.0% acetic acid and acetonitrile as mobile phase at a flow rate of 0.8 mL/min in the gradient elution mode. The method was fully validated in terms of linearity (r2 > 0.9990, 10‒350 mg/L, precision (both intra-day and inter-day RSD < 4.22%, accuracy (97.31%‒104.66%, specificity, robustness (0.59% < RSD < 2.86%, limit of detection and quantification. The switching method significantly improved the sensitivities of most phenolics studied in comparison with the standard constant wavelength detection (280 nm. The proposed method has been successfully applied to the determination of 14 phenolic compounds in 89 varieties of one-year-old Chinese grape one-year-canes. Grape canes contain many phenolics, especially trans-resveratrol, (‒-epicatechin, and (+-catechin.

  2. A New Fault-tolerant Switched Reluctance Motor with reliable fault detection capability

    DEFF Research Database (Denmark)

    Lu, Kaiyuan

    2014-01-01

    For reliable fault detection, often, search coils are used in many fault-tolerant drives. The search coils occupy extra slot space. They are normally open-circuited and are not used for torque production. This degrades the motor performance, increases the cost and manufacture complexity. A new...... Fault-Tolerant Switched Reluctance (FTSR) motor is proposed in this paper. A unique feature of this special design is that it allows use of the unexcited phase coils as search coils for fault detection. Therefore this new motor has all the advantages of using search coils for reliable fault detection...

  3. Resistance switching of epitaxial VO2/Al2O3 heterostructure at room temperature induced by organic liquids

    Directory of Open Access Journals (Sweden)

    Mengmeng Yang

    2015-03-01

    Full Text Available We studied using organic liquids (cyclohexane, n-butanol, and ethylene glycol to modulate the transport properties at room temperature of an epitaxial VO2 film on a VO2/Al2O3 heterostructure. The resistance of the VO2 film increased when coated with cyclohexane or n-butanol, with maximum changes of 31% and 3.8%, respectively. In contrast, it decreased when coated with ethylene glycol, with a maximum change of −7.7%. In all cases, the resistance recovered to its original value after removing the organic liquid. This organic-liquid-induced reversible resistance switching suggests that VO2 films can be used as organic molecular sensors.

  4. Fault Detection for Wireless Networked Control Systems with Stochastic Switching Topology and Time Delay

    Directory of Open Access Journals (Sweden)

    Pengfei Guo

    2014-01-01

    Full Text Available This paper deals with the fault detection problem for a class of discrete-time wireless networked control systems described by switching topology with uncertainties and disturbances. System states of each individual node are affected not only by its own measurements, but also by other nodes’ measurements according to a certain network topology. As the topology of system can be switched in a stochastic way, we aim to design H∞ fault detection observers for nodes in the dynamic time-delay systems. By using the Lyapunov method and stochastic analysis techniques, sufficient conditions are acquired to guarantee the existence of the filters satisfying the H∞ performance constraint, and observer gains are derived by solving linear matrix inequalities. Finally, an illustrated example is provided to verify the effectiveness of the theoretical results.

  5. Voltage switching technique for detecting nuclear spin polarization in a quantum dot

    International Nuclear Information System (INIS)

    Takahashi, Ryo; Kono, Kimitoshi; Tarucha, Seigo; Ono, Keiji

    2010-01-01

    We have introduced a source-drain voltage switching technique for studying nuclear spins in a vertical double quantum dot. Switching the source-drain voltage between the spin-blockade state and the zero-bias Coulomb blockade state can tune the energy difference between the spin singlet and triplet, and effectively turn on/off the hyperfine interaction. Since the change in the nuclear spin state affects the source-drain current, nuclear spin properties can only be detected by transport measurement. Using this technique, we have succeeded in measuring the timescale of nuclear spin depolarization. Furthermore, combining this technique and an RF ac magnetic field, we successfully detected continuous-wave NMR signals of 75 As, 69 Ga, and 71 Ga, which are contained in a quantum dot. (author)

  6. Reverse bistable effect in ferroelectric liquid crystal devices with ultra-fast switching at low driving voltage.

    Science.gov (United States)

    Guo, Qi; Zhao, Xiaojin; Zhao, Huijie; Chigrinov, V G

    2015-05-15

    In this Letter, reverse bistable effect with deep-sub-millisecond switching time is first reported in ferroelectric liquid crystal (FLC) devices using a homogeneous photo-alignment technique. It is indicated by our experimental results that both the anchoring energy and the dielectric property of the FLC's alignment layer is critical for the existence of the reverse bistable effect. In addition, with the derived criteria of the reverse bistable effect, we quantitatively analyze the switching dynamics of the reverse bistable FLC and the transition condition between the traditional bistability and our presented reverse bistability. Moreover, the fabricated FLC device exhibits an ultra-fast switching of ∼160  μs and a high contrast ratio of 1000:1, both of which were measured at a low driving voltage of 11 V. The featured deep-sub-millisecond switching time is really advantageous for our presented reverse bistable FLC devices, which enables a significant quality improvement of the existing optical devices, as well as a wide range of new applications in photonics and display areas.

  7. Liquid scintillators and composites in fast neutron detection

    Science.gov (United States)

    Iwanowska, J.; Swiderski, L.; Moszynski, M.

    2012-04-01

    Helium-3 world crisis requires a development of new methods of neutron detection to replace commonly used 3He proportional counters. One of the option is application of liquid scintillators widely used in detection of fast neutrons, mostly in physics experiments, especially in applications where large volumes are required. Moreover, recently studied 10B loaded liquid scintillators cover detection of neutrons down to thermal energy. The several years' studies of liquid scintillators in our laboratory, brought us a knowledge about their efficiency to neutron detection, gamma sensitivity, etc. We have also tested composite scintillators, which are an alternative to organic single crystals, used in the 70's last century. In the report, we will present the results of the study of several liquid scintillators, also 10B loaded, as well as high flashpoint ones. We also show the neutron detection properties of some samples of composite scintillators. Composites are based on small grains of p-terphenyl or stilbene, introduced into a polymer matrix, which acts as a diffuser. The composite is encapsulated in a housing made of organic glass. P-terphenyl and stilbene are organic scintillators, which were commonly used in the seventies last century. They are characterized by good neutron/gamma discrimination properties. The present studies covers neutron/gamma discrimination by the zero-crossing method, a comparison of detection efficiency of liquid scintillators to 3He detectors and methods to reduce their gamma-ray sensitivity. In conclusion, a detection system, based on several small liquid cells of 2'' × 2'', is preferred, with pulse shape discrimination circuit equipped with the pile-up rejection circuit (PUR), as well as lead and tin shielding.

  8. Flexoelectric effect in an in-plane switching (IPS) liquid crystal cell for low-power consumption display devices

    Science.gov (United States)

    Kim, Min Su; Bos, Philip J.; Kim, Dong-Woo; Yang, Deng-Ke; Lee, Joong Hee; Lee, Seung Hee

    2016-01-01

    Technology of displaying static images in portable displays, advertising panels and price tags pursues significant reduction in power consumption and in product cost. Driving at a low-frequency electric field in fringe-field switching (FFS) mode can be one of the efficient ways to save powers of the recent portable devices, but a serious drop of image-quality, so-called image-flickering, has been found in terms of the coupling of elastic deformation to not only quadratic dielectric effect but linear flexoelectric effect. Despite of the urgent requirement of solving the issue, understanding of such a phenomenon is yet vague. Here, we thoroughly analyze and firstly report the flexoelectric effect in in-plane switching (IPS) liquid crystal cell. The effect takes place on the area above electrodes due to splay and bend deformations of nematic liquid crystal along oblique electric fields, so that the obvious spatial shift of the optical transmittance is experimentally observed and is clearly demonstrated based on the relation between direction of flexoelectric polarization and electric field polarity. In addition, we report that the IPS mode has inherent characteristics to solve the image-flickering issue in the low-power consumption display in terms of the physical property of liquid crystal material and the electrode structure. PMID:27731372

  9. Misfire detection based on switched state observer of hybrid system in internal combustion engine

    Science.gov (United States)

    Zhang, Yu; Zhou, Tonglin; Zheng, Taixiong; Han, Weimin; Tan, Rui; Wang, Yanjun

    2017-04-01

    This paper proposes a novel switched state observer of hybrid system using Luenberger sliding mode observer to estimate crankshaft angular acceleration which is further applied to detect misfire fault. The output error of hybrid system of internal combustion engine (engine speed) and the designed observer (estimated speed) is taken as input of observer to estimate crankshaft acceleration. Convergence of hybrid system is proven through Lyapunov stability theory. The experimental results show that the presented estimated technique has a higher accuracy and can be effectively used to misfire detection compared with reduced-order observer and sliding mode observer.

  10. Effect of gold nano-particles on switch-on voltage and relaxation frequency of nematic liquid crystal cell

    Directory of Open Access Journals (Sweden)

    M. Inam

    2011-12-01

    Full Text Available We report the observation of large changes in the electro-optical properties of nematic liquid crystal (NLC due to inclusion of small concentration of 10 nm diameter gold nanoparticles (GNPs. It is observed that GNPs lower switch-on voltage and also lower the relaxation frequency with applied voltage (AC field to NLC cell. These studies of GNP doped NLC cell have been done using optical interferometry and capacity measurement by impedance analyzer. The change in threshold voltage and relaxation frequency by doping GNPs in NLC is explained theoretically.

  11. Identification and quantification of flavonoids in human urine samples by column switching liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, Salka E.; Freese, R.; Cornett, C.

    2000-01-01

    A rapid and sensitive high-performance liquid chromatographic mass spectrometric (HPLC-MS) method is described for the determination and quantification of 12 dietary flavonoid glycosides and aglycons in human urine samples. Chromatographic separation of the analytes of interest was achieved...... by column-switching, using the first column (a Zorbax 300SB C-3 column) for sample cleanup and eluting the heart-cut flavonoid fraction onto the second column (a Zorbax SE C-18 column) for separation and detection by ultraviolet and atmospheric pressure chemical ionization MS using single ion monitoring...... of variation for the analysis of the 12 different flavonoids in quality control urine samples were 12.3% on average (range 11.0-13.7%, n = 24, reproducibility) and the repeatability of the assay were 5.0% (mean, range 0.1-14.8%, it = 12). A subset of 10 urine samples from a human dietary intervention study...

  12. Detection of Ionic liquid using terahertz time-domain spectroscopy

    Science.gov (United States)

    Wang, Cuicui; Zhao, Xiaojing; Liu, Shangjian; Zuo, Jian; Zhang, Cunlin

    2018-01-01

    Terahertz (THz, THz+1012Hz) spectroscopy is a far-infrared analytical technology with spectral bands locating between microware and infrared ranges. Being of excellent transmission, non-destruction and high discrimination, this technology has been applied in various fields such as physics, chemistry, nondestructive detection, communication, biomedicine public security. Terahertz spectrum is corresponding with vibration and rotation of liquid molecules, which is suitable to identify and study the liquid molecular dynamics. It is as a powerful spectral detection technology, terahertz time-domain spectroscopy is widely used in solution detection. can enable us to extract the material parameters or dielectric spectrum that show material micro-structure and dynamics by measuring amplitude and phase from coherent terahertz pulses. Ionic liquid exists in most biological tissues, and it is very important for life. It has recently been suggested that near-fired terahertz ionic contrast microscopy can be employed to image subtle changes in ionic concentrations arising from neuronal activity. In this paper, we detected Ionic liquid with different concentrations at room temperature by THz-TDS technique in the range of 0.2-1.5 THz. The liquid cell with a thickness of 0.2mm is made of quartz. The absorption coefficient, refractive index and dielectric function of solutions can be extracted based on THz-TDS. We use an expanded model for fitting the dielectric function based on a combination of a Debye relation for the anions and cations. We find A linear increase of the real and imaginary part of the dielectric function compared with pure water with increasing ion concentrations. A good agreement between the model and the experimental results is obtained. By means of dielectric relaxation process, it was found that the characteristic time of molecular movement and the information related to the liquid molecular structure and movement was obtained.

  13. An Electromagnetic Resonance Circuit for Liquid Level Detection

    Science.gov (United States)

    Hauge, B. L.; Helseth, L. E.

    2012-01-01

    Electromagnetic resonators are often used to detect foreign materials. Here we present a simple experiment for the measurement of liquid level. The resonator, consisting of a coil and a capacitor, is brought to resonance by an external magnetic field source, and the corresponding resonance frequency is determined using Fourier analysis combined…

  14. Reversible Switched Detection of Dihydroxybenzenes Using a Temperature-sensitive Electrochemical Sensing Film

    International Nuclear Information System (INIS)

    Zhou, Yuanqing; Chen, Chao; Zhao, Jia; Fei, Junjie; Ding, Yonglan; Cai, Yuanli

    2016-01-01

    A composite sensing film (PGS), consisting of poly(N-isopropylacrylamide) 101 -b-poly(2-acrylamidoethyl benzoate) 37 (PNIPAM 101 -b-PAAEB 37 ), graphene oxides (GO) and short multi-walled carbon nanotubes (SMWCNs), was fabricated and modified onto a working electrode. The sensing film served as a reversible switch for electrochemical detection, with the switching behaviour responding to thermal stimuli. Cyclic voltammetry of hydroquinone (HQ) and catechol (CC) at the PGS film-modified electrode displayed large peak currents when the temperature was above the lower critical solution temperature (LCST) of PNIPAM 101 -b-PAAEB 37 . These large currents disappeared at low temperature. Interestingly, the composite film showed reversed electrochemical “on/off” behaviour as compared to previously reported switchable electrodes, which were modified only with temperature-responsive polymers. This behaviour can be attributed to the temperature-dependent phase transition of PNIPAM 101 -b-PAAEB 37 and cooperative effects of the other two functional components (SMWCNs and GO). The repeatable “on/off” switching of the voltammetric responses of HQ/CC on the PGS-modified electrode were achieved via regulating the solution temperature. This research provides a new type of temperature-controlled switchable electrode with potential applications in the design of novel sensors, fuel cells and electronics.

  15. Using Signal Envelope Detection for Online and Offline RF MEMS Switch Testing

    Directory of Open Access Journals (Sweden)

    E. Simeu

    2008-01-01

    Full Text Available The test of radiofrequency (RF integrated circuits at their ever-increasing operating frequency range requires sophisticated test equipment and is time-consuming and, therefore, very expensive. This paper introduces a new method combining low-frequency actuation signal as test stimuli and signal envelope detection applied on the RF output signal in order to provide a low-cost mean for production testing of RF MEMS switches embedded in system-in-package (SiP devices. The proposed approach uses the principle of alternate test that replaces conventional specification-based testing procedures. The basic idea is to extract the high-frequency characteristics of the switch from the signal envelope of the response. Output parameters like “on” and “off” transition time are extracted at low frequency and used in a regression process to predict RF conventional specifications like S-parameters. The paper also provides a set of recursive estimation algorithms suitable for online testing. In this context, “on” and “off” transition time estimated from the output low-frequency envelope is used as test metrics and is concurrently updated using recursive algorithms. Validation results obtained on a capacitive RF switch model are presented.

  16. Pulse Q-switched Nd:YAG laser ablation grown cinnamon nanomorphologies: Influence of different liquid medium

    Science.gov (United States)

    Salim, Ali Aqeel; Bidin, Noriah

    2017-12-01

    Broad range of biomedical applications demands accurate synthesis and characterization of various nanoparticles. We report the characterization of cinnamon nanoparticles (CNPs) grown via simple pulsed laser ablation in liquid (PLAL). The influence of different liquid media (olive oil, ethanol, and citric acid each of volume 4 ml) on the growth morphology, structure and optical properties of CNPs is determined. Q-switched 1064-Nd: YAG laser of 10 ns pulse duration, 1 Hz repetition rate, 532 nm s harmonic generation and laser fluence of 6.37 J/cm2 is used to irradiate the cinnamon targets immersed in those liquids. Samples are characterized using TEM, HRTEM, SAED, FTIR, UV-Vis and Photoluminescence measurements. TEM images revealed the nucleation of CNPs of average size 18.36 nm (in olive oil), 21.48 nm (in ethanol), and 29.56 nm (in citric acid). Morphology of CNPs is demonstrated to be sensitive to the liquid medium. Our simple and innovative method may constitute a basis to produce CNPs of desired size distribution potential for the development of nanobiomedicine.

  17. Open-Switch Fault Detection Method of a Back-to-Back Converter Using NPC Topology for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Lee, June-Seok; Lee, Kyo_Beum; Blaabjerg, Frede

    2015-01-01

    In wind turbine generation (WTG) systems, a back-to-back converter with a neutral-point-clamped (NPC) topology is widely used because this topology has more advantages than a conventional two-level topology, particularly when operating at high power. There are 12 switches in the NPC topology....... An open-switch fault in the NPC rectifier of the back-to-back converter leads to the distortion of the input current and torque vibration in the system. Additionally, an open-switch fault in the NPC inverter of the back-to-back converter causes the distortion of the output current. Furthermore, the WTG...... system can break down in the worst case scenario. To improve the reliability of WTG systems, an open-switch fault detection method for back-to-back converters using the NPC topology is required. This study analyzes effects of inner and outer open-switch faults of the NPC rectifier and inverter...

  18. Rapid determination of 12 antibiotics and caffeine in sewage and bioreactor effluent by online column-switching liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Lima Gomes, Paulo C F; Tomita, Inês N; Santos-Neto, Álvaro J; Zaiat, Marcelo

    2015-11-01

    This study presents a column-switching solid-phase extraction online-coupled to a liquid chromatography/tandem mass spectrometry (SPE-LC-MS/MS) method for simultaneous analysis of 12 antibiotics (7 sulfonamides and 5 fluoroquinolones) and caffeine detected in the sewage and effluent of a pilot anaerobic reactor used in sewage treatment. After acidification and filtration, the samples were directly injected into a simple and conventional LC system. Backflush and foreflush modes were compared based on the theoretical plates and peak asymmetry observed. The method was tested in terms of detection (MDL) and quantification limit (MQL), linearity, relative recovery, and precision intra- and inter-day in lab-made sewage samples. The method presented suitable figures of merit in terms of detection, varying from 8.00 × 10(-5) to 6.00 × 10(-2) ng (0.800 up to 600 ng L(-1); caffeine) with direct injection volume of only 100 μL and 13 min of total analysis time (sample preparation and chromatographic run). When the method was applied in the analysis of sewage and effluent of the anaerobic reactor (n = 15), six antibiotics and caffeine were detected in concentrations ranging from 0.018 to 1097 μg L(-1). To guarantee a reliable quantification, standard addition was used to overcome the matrix effect.

  19. Levothyroxine Therapy: Changes of TSH Levels by Switching Patients from Tablet to Liquid Formulation. A Systematic Review and Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Camilla Virili

    2018-01-01

    Full Text Available BackgroundIn the last years, levothyroxine (LT4 has been commercialized also in liquid formulation, which is less sensitive to the factors known to reduce the absorption of tablet LT4. To date, there is no robust information that liquid LT4 can improve pharmacologic thyroid homeostasis of patients with reduced efficacy of tablet LT4. This analysis aimed at achieving solid evidence that switching thyroxine treatment from tablet to liquid preparation improves patients’ TSH levels.MethodsThe search was performed in PubMed/MEDLINE and Scopus database based on the terms “thyroid,” “levothyroxine,” and “liquid,” and updated until September 25, 2017. Studies were included only if they described patients with suboptimal TSH on tablet LT4, subsequently switched to liquid LT4.ResultsThe literature search retrieved 462 articles and six were finally included. The pooled mean difference of TSH value between tablet and liquid LT4 was 4.23 mIU/L (95% CI from 3.69 to 4.77. Mild heterogeneity was found (I2 60%. Overall mean difference of TSH was significant (p < 0.0001.ConclusionThe present meta-analysis showed that patients with suboptimal TSH on tablet LT4 can have a significantly improved TSH by switching to liquid LT4 formulation at unchanged dose.

  20. Liquid-liquid extraction and liquid chromatography-mass spectrometry detection of curcuminoids from bacterial culture medium.

    Science.gov (United States)

    Tan, Suryani; Rupasinghe, Thusitha W T; Tull, Dedreia L; Augustin, Mary Ann; Gras, Sally L

    2015-04-15

    Liquid chromatography-mass spectrometry (LC-MS) has been used to detect polyphenolic curcuminoids found in turmeric but studies of metabolism by bacterial and mammalian cells in vitro are compromised by poor recovery from the culture medium. We report a liquid-liquid extraction procedure with ethyl acetate and use LC-MS to quantify extracted curcuminoids. Ethyl acetate allows recoveries of ∼ 80-86% of curcuminoids from the bacterial growth medium, bacterial cell lysate and combined bacterial cell and growth medium matrices; a clear improvement over acetonitrile where recoveries were ∼ 25-66%. This optimised method will enable studies of curcuminoid metabolism and may be applicable to other hydrophobic polyphenolic compounds. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Detection of Internal Short Circuit in Lithium Ion Battery Using Model-Based Switching Model Method

    Directory of Open Access Journals (Sweden)

    Minhwan Seo

    2017-01-01

    Full Text Available Early detection of an internal short circuit (ISCr in a Li-ion battery can prevent it from undergoing thermal runaway, and thereby ensure battery safety. In this paper, a model-based switching model method (SMM is proposed to detect the ISCr in the Li-ion battery. The SMM updates the model of the Li-ion battery with ISCr to improve the accuracy of ISCr resistance R I S C f estimates. The open circuit voltage (OCV and the state of charge (SOC are estimated by applying the equivalent circuit model, and by using the recursive least squares algorithm and the relation between OCV and SOC. As a fault index, the R I S C f is estimated from the estimated OCVs and SOCs to detect the ISCr, and used to update the model; this process yields accurate estimates of OCV and R I S C f . Then the next R I S C f is estimated and used to update the model iteratively. Simulation data from a MATLAB/Simulink model and experimental data verify that this algorithm shows high accuracy of R I S C f estimates to detect the ISCr, thereby helping the battery management system to fulfill early detection of the ISCr.

  2. Diversity of the Lactic Acid Bacterium and Yeast Microbiota in the Switch from Firm- to Liquid-Sourdough Fermentation

    Science.gov (United States)

    Di Cagno, Raffaella; Pontonio, Erica; Buchin, Solange; De Angelis, Maria; Lattanzi, Anna; Valerio, Francesca; Calasso, Maria

    2014-01-01

    Four traditional type I sourdoughs were comparatively propagated (28 days) under firm (dough yield, 160) and liquid (dough yield, 280) conditions to mimic the alternative technology options frequently used for making baked goods. After 28 days of propagation, liquid sourdoughs had the lowest pH and total titratable acidity (TTA), the lowest concentrations of lactic and acetic acids and free amino acids, and the most stable density of presumptive lactic acid bacteria. The cell density of yeasts was the highest in liquid sourdoughs. Liquid sourdoughs showed simplified microbial diversity and harbored a low number of strains, which were persistent. Lactobacillus plantarum dominated firm sourdoughs over time. Leuconostoc lactis and Lactobacillus brevis dominated only some firm sourdoughs, and Lactobacillus sanfranciscensis persisted for some time only in some firm sourdoughs. Leuconostoc citreum persisted in all firm and liquid sourdoughs, and it was the only species detected in liquid sourdoughs at all times; it was flanked by Leuconostoc mesenteroides in some sourdoughs. Saccharomyces cerevisiae, Candida humilis, Saccharomyces servazzii, Saccharomyces bayanus-Kazachstania sp., and Torulaspora delbrueckii were variously identified in firm and liquid sourdoughs. A total of 197 volatile components were identified through purge and trap–/solid-phase microextraction–gas chromatography-mass spectrometry (PT–/SPME–GC-MS). Aldehydes, several alcohols, and some esters were at the highest levels in liquid sourdoughs. Firm sourdoughs mainly contained ethyl acetate, acetic acid, some sulfur compounds, and terpenes. The use of liquid fermentation would change the main microbial and biochemical features of traditional baked goods, which have been manufactured under firm conditions for a long time. PMID:24632249

  3. Switching between transparent and translucent states of a two-dimensional liquid crystal phase grating device with crossed interdigitated electrodes.

    Science.gov (United States)

    Choi, Tae-Hoon; Huh, Jae-Won; Woo, Jae-Hyeon; Kim, Jin-Hun; Jo, Young-Seo; Yoon, Tae-Hoon

    2017-05-15

    We report an electrically-switchable two-dimensional liquid crystal (LC) phase grating device for window display applications. The device consists of the top and bottom substrates with crossed interdigitated electrodes and vertically-aligned LCs sandwiched between the two substrates. The device, switchable between the transparent and translucent states by applying an electric field, can provide high haze by the strong diffraction effect thanks to a large spatial phase difference with little dependence on the azimuth angle. We found that the device has outstanding features, such as a low operating voltage, high transparency, and wide viewing angle characteristics in the transparent state and high haze in the translucent state. Moreover, we achieved submillisecond switching between transparent and translucent states by employing the overdrive scheme and a vertical trigger pulse.

  4. A liquid lens switching-based motionless variable fiber-optic delay line

    Science.gov (United States)

    Khwaja, Tariq Shamim; Reza, Syed Azer; Sheikh, Mumtaz

    2018-05-01

    We present a Variable Fiber-Optic Delay Line (VFODL) module capable of imparting long variable delays by switching an input optical/RF signal between Single Mode Fiber (SMF) patch cords of different lengths through a pair of Electronically Controlled Tunable Lenses (ECTLs) resulting in a polarization-independent operation. Depending on intended application, the lengths of the SMFs can be chosen accordingly to achieve the desired VFODL operation dynamic range. If so desired, the state of the input signal polarization can be preserved with the use of commercially available polarization-independent ECTLs along with polarization-maintaining SMFs (PM-SMFs), resulting in an output polarization that is identical to the input. An ECTL-based design also improves power consumption and repeatability. The delay switching mechanism is electronically-controlled, involves no bulk moving parts, and can be fully-automated. The VFODL module is compact due to the use of small optical components and SMFs that can be packaged compactly.

  5. Entropy Based Detection of DDoS Attacks in Packet Switching Network Models

    Science.gov (United States)

    Lawniczak, Anna T.; Wu, Hao; di Stefano, Bruno

    Distributed denial-of-service (DDoS) attacks are network-wide attacks that cannot be detected or stopped easily. They affect “natural” spatio-temporal packet traffic patterns, i.e. “natural distributions” of packets passing through the routers. Thus, they affect “natural” information entropy profiles, a sort of “fingerprints”, of normal packet traffic. We study if by monitoring information entropy of packet traffic through selected routers one may detect DDoS attacks or anomalous packet traffic in packet switching network (PSN) models. Our simulations show that the considered DDoS attacks of “ping” type cause shifts in information entropy profiles of packet traffic monitored even at small sets of routers and that it is easier to detect these shifts if static routing is used instead of dynamic routing. Thus, network-wide monitoring of information entropy of packet traffic at properly selected routers may provide means for detecting DDoS attacks and other anomalous packet traffics.

  6. Sensitive detection of alkaline phosphatase by switching on gold nanoclusters fluorescence quenched by pyridoxal phosphate.

    Science.gov (United States)

    Halawa, Mohamed Ibrahim; Gao, Wenyue; Saqib, Muhammad; Kitte, Shimeles Addisu; Wu, Fengxia; Xu, Guobao

    2017-09-15

    In this work, we designed highly sensitive and selective luminescent detection method for alkaline phosphatase using bovine serum albumin functionalized gold nanoclusters (BSA-AuNCs) as the nanosensor probe and pyridoxal phosphate as the substrate of alkaline phosphatase. We found that pyridoxal phosphate can quench the fluorescence of BSA-AuNCs and pyridoxal has little effect on the fluorescence of BSA-AuNCs. The proposed mechanism of fluorescence quenching by PLP was explored on the basis of data obtained from high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), UV-vis spectrophotometry, fluorescence spectroscopy, fluorescence decay time measurements and circular dichroism (CD) spectroscopy. Alkaline phosphatase catalyzes the hydrolysis of pyridoxal phosphate to generate pyridoxal, restoring the fluorescence of BSA-AuNCs. Therefore, a recovery type approach has been developed for the sensitive detection of alkaline phosphatase in the range of 1.0-200.0U/L (R 2 =0.995) with a detection limit of 0.05U/L. The proposed sensor exhibit excellent selectivity among various enzymes, such as glucose oxidase, lysozyme, trypsin, papain, and pepsin. The present switch-on fluorescence sensing strategy for alkaline phosphatase was successfully applied in human serum plasma with good recoveries (100.60-104.46%), revealing that this nanosensor probe is a promising tool for ALP detection. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. An electronic channel switching-based aptasensor for ultrasensitive protein detection

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongbo; Wang Cui [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Wu Zaisheng, E-mail: wuzaisheng@163.com [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Lu Limin; Qiu Liping; Zhou Hui; Shen Guoli [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Yu Ruqin, E-mail: rqyu@hnu.edu.cn [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-01-03

    Highlights: Black-Right-Pointing-Pointer Target IgE is successfully designed to serve as a barrier to separate enzyme from its substrate. Black-Right-Pointing-Pointer This sensing platform of electronic channel switching-based aptasensor can be simply manipulated. Black-Right-Pointing-Pointer The stable hairpin structure of anti-IgE aptamer is utilized to detect target IgE. Black-Right-Pointing-Pointer The sensor is ultrasensitive sensitivity, excellent selectivity and small volume of sample. Black-Right-Pointing-Pointer It is a powerful platform to be further expanded to detect more kinds of proteins and even cells. - Abstract: Due to the ubiquity and essential of the proteins in all living organisms, the identification and quantification of disease-specific proteins are particularly important. Because the conformational change of aptamer upon its target or probe/target/probe sandwich often is the primary prerequisite for the design of an electrochemical aptameric assay system, it is extremely difficult to construct the electrochemical aptasensor for protein assay because the corresponding aptamers cannot often meet the requirement. To circumvent the obstacles mentioned, an electronic channel switching-based (ECS) aptasensor for ultrasensitive protein detection is developed. The essential achievement made is that an innovative sensing concept is proposed: the hairpin structure of aptamer is designed to pull electroactive species toward electrode surface and makes the surface-immobilized IgE serve as a barrier that separates enzyme from its substrate. It seemingly ensures that the ECS aptasensor exhibits most excellent assay features, such as, a detection limit of 4.44 Multiplication-Sign 10{sup -6} {mu}g mL{sup -1} (22.7 fM, 220 zmol in 10-{mu}L sample) (demonstrating a 5 orders of magnitude improvement in detection sensitivity compared with classical electronic aptasensors) and dynamic response range from 4.44 Multiplication-Sign 10{sup -6} to 4.44 Multiplication

  8. Beauty hinders attention switch in change detection: the role of facial attractiveness and distinctiveness.

    Science.gov (United States)

    Chen, Wenfeng; Liu, Chang Hong; Nakabayashi, Kazuyo

    2012-01-01

    Recent research has shown that the presence of a task-irrelevant attractive face can induce a transient diversion of attention from a perceptual task that requires covert deployment of attention to one of the two locations. However, it is not known whether this spontaneous appraisal for facial beauty also modulates attention in change detection among multiple locations, where a slower, and more controlled search process is simultaneously affected by the magnitude of a change and the facial distinctiveness. Using the flicker paradigm, this study examines how spontaneous appraisal for facial beauty affects the detection of identity change among multiple faces. Participants viewed a display consisting of two alternating frames of four faces separated by a blank frame. In half of the trials, one of the faces (target face) changed to a different person. The task of the participant was to indicate whether a change of face identity had occurred. The results showed that (1) observers were less efficient at detecting identity change among multiple attractive faces relative to unattractive faces when the target and distractor faces were not highly distinctive from one another; and (2) it is difficult to detect a change if the new face is similar to the old. The findings suggest that attractive faces may interfere with the attention-switch process in change detection. The results also show that attention in change detection was strongly modulated by physical similarity between the alternating faces. Although facial beauty is a powerful stimulus that has well-demonstrated priority, its influence on change detection is easily superseded by low-level image similarity. The visual system appears to take a different approach to facial beauty when a task requires resource-demanding feature comparisons.

  9. Liquid metal-to-gas leak-detection instruments

    International Nuclear Information System (INIS)

    Matlin, E.; Witherspoon, J.E.; Johnson, J.L.

    1982-01-01

    It is desirable for liquid-metal-cooled reactors that small liquid metal-to-gas leaks be reliably detected. Testing has been performed on a number of detection systems to evaluate their sensitivity, response time, and performance characteristics. This testing has been scheduled in three phases. The first phase was aimed at screening out the least suitable detectors and optimizing the performance of the most promising. In the second phase, candidates were tested in a 1500 ft 3 walk-in type enclosure in which leaks were simulated on 24-in. and 3-in. piping. In the third phase of testing, selected type detectors were tested in the 1500-ft 3 enclosure with Clinch River Breeder Reactor Plant (CRBRP) pipe insulation configurations and detector tubing configuration with cell gas recirculation simulated. Endurance testing of detection equipment was also performed as part of this effort. Test results have been shown that aerosol-type detectors will reliably detect leaks as small as a few grams per hour when sampling pipe insulation annuli

  10. Utilizing Metalized Fabrics for Liquid and Rip Detection and Localization

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Stephen [University of Tennessee, Knoxville (UTK); Mahan, Cody [Western Kentucky University; Kuhn, Michael J [ORNL; Rowe, Nathan C [ORNL

    2013-01-01

    This paper proposes a novel technique for utilizing conductive textiles as a distributed sensor for detecting and localizing liquids (e.g., blood), rips (e.g., bullet holes), and potentially biosignals. The proposed technique is verified through both simulation and experimental measurements. Circuit theory is utilized to depict conductive fabric as a bounded, near-infinite grid of resistors. Solutions to the well-known infinite resistance grid problem are used to confirm the accuracy and validity of this modeling approach. Simulations allow for discontinuities to be placed within the resistor matrix to illustrate the effects of bullet holes within the fabric. A real-time experimental system was developed that uses a multiplexed Wheatstone bridge approach to reconstruct the resistor grid across the conductive fabric and detect liquids and rips. The resistor grid model is validated through a comparison of simulated and experimental results. Results suggest accuracy proportional to the electrode spacing in determining the presence and location of discontinuities in conductive fabric samples. Future work is focused on refining the experimental system to provide more accuracy in detecting and localizing events as well as developing a complete prototype that can be deployed for field testing. Potential applications include intelligent clothing, flexible, lightweight sensing systems, and combat wound detection.

  11. Sensorless control for switched reluctance motor based on special position detection.

    Science.gov (United States)

    Shao, Jie; Deng, Zhiquan; Gu, Yu

    2017-09-01

    This paper proposes a new sensorless control approach for switched reluctance motor (SRM) in the single pulse control mode in high speed operation. The sensorless method uses the cross point position of transformer electromotive force (EMF) and motional back electromotive force (BEMF) to estimate the rotor position. The cross point position can be derived from the inductance model of SRM, and it is regarded as reference position. The rotor position can be calculated by detecting the special position for each electrical cycle. The proposed position estimation method is not affected by the magnetic saturation of SRM. Importantly, no additional hardware and no complicated computation or memory storage are required with the proposed method. Finally, the simulation and experimental results on a three-phase 12/8-pole SRM demonstrate the validity of the proposed sensorless scheme. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Capillary column switching restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry system for simultaneous and direct analysis of drugs in biofluids.

    Science.gov (United States)

    Santos-Neto, Alvaro J; Markides, Karin E; Sjöberg, Per J R; Bergquist, Jonas; Lancas, Fernando M

    2007-08-15

    Capillary online restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry (RAM-LC-ESI-MS/MS) for direct analysis of drugs and metabolites spiked in biological fluids was developed. Using a column switching setup it was possible to perform effective sample preparation and analysis of raw biological fluids (plasma and urine) without matrix effects in the electrospray mass spectrometric detection step. The peak focusing efficiency of the extraction column was more effective in backflush compared to foreflush mode. The system was able to concentrate diminished samples of polar drugs and their metabolites reaching quantifiable results as low as 1 ng/mL utilizing a sample volume of only 333 nL of biofluids. New column hardware was developed to circumvent clogging problems experienced with plasma injections. The glass fiber filter frit, which is commonly used, was replaced with a short piece of 20 microm i.d. fused silica capillary. The extraction columns were able to handle up to 60 injections and showed a high loading capacity, making the saturation of the MS detector the limiting factor on the linear dynamic range. The simultaneous separation and detection of 10 drugs and metabolites was obtained in 8 min of analysis, including the online sample preparation and enrichment step.

  13. A step toward CNO solar neutrino detection in liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Villante, F.L., E-mail: villante@lngs.infn.it [Universita dell' Aquila, Dipartimento di Fisica, L' Aquila (Italy); INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Ianni, A. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Lombardi, F. [Universita dell' Aquila, Dipartimento di Fisica, L' Aquila (Italy); INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Pagliaroli, G.; Vissani, F. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy)

    2011-07-11

    The detection of CNO solar neutrinos in ultrapure liquid scintillator detectors is limited by the background produced by bismuth-210 nuclei that undergo {beta}-decay to polonium-210 with a lifetime of {approx}7 days. Polonium-210 nuclei are unstable and decay with a lifetime equal to {approx}200 days emitting {alpha} particles that can be also detected. In this Letter, we show that the Bi-210 background can be determined by looking at the time evolution of {alpha}-decay rate of Po-210, provided that {alpha} particle detection efficiency is stable over the data acquisition period and external sources of Po-210 are negligible. A sufficient accuracy can be obtained in a relatively short time. As an example, if the initial Po-210 event rate is {approx}2000 cpd/100 ton or lower, a Borexino-like detector could start discerning CNO neutrino signal from Bi-210 background in {Delta}t{approx}1 yr.

  14. A 65-kV insulated gate bipolar transistor switch applied in damped AC voltages partial discharge detection system.

    Science.gov (United States)

    Jiang, J; Ma, G M; Luo, D P; Li, C R; Li, Q M; Wang, W

    2014-02-01

    Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.

  15. Utilizing metalized fabrics for liquid and rip detection and localization

    Science.gov (United States)

    Holland, Stephen A.; Mahan, Cody A.; Kuhn, Michael J.; Rowe, Nathan C.

    2013-05-01

    This paper proposes a novel technique for utilizing electrically conductive textiles as a distributed sensor for detecting and localizing liquids (e.g., blood), damage (e.g., rips, cuts, bullet holes) and, potentially, biosignals. The proposed technique is verified through both simulation and experimental measurements. Circuit theory is employed to depict conductive fabric as a bounded, near-infinite grid of resistors. Solutions to the well-known infinite resistance grid problem are used to confirm the accuracy and validity of this modeling approach. Simulations allow for discontinuities to be placed within the resistor matrix to illustrate the effects of bullet holes within the fabric. A real-time experimental system was developed that uses a multiplexed, Wheatstone bridge measurement approach to determine the resistances of a coarse electrode grid across the conductive fabric. Non-uniform resistance values of the grid infer the presence of liquids and rips in the fabric. The resistor-grid model is validated through a comparison of simulated and experimental results. Results suggest accuracy proportional to the electrode spacing in determining the presence and location of disturbances in conductive fabric samples. Future work is focused on refining the experimental system to provide more accuracy in detecting and localizing events (although just the knowledge of a penetration may be adequate for some intended applications) as well as developing a complete prototype that can be deployed for field testing. Potential applications include intelligent clothing, flexible, lightweight sensing systems, and combat wound detection.

  16. Change Detection in Visual Short-Term Memory: The Relative Impact of Pairwise Switches and Identity Substitutions.

    Science.gov (United States)

    Sapkota, Raju P; Pardhan, Shahina; van der Linde, Ian

    2015-01-01

    Numerous kinds of visual event challenge our ability to keep track of the objects that populate our visual environment from moment to moment. These include blinks, occlusion, shifting visual attention, and changes to object's visual and spatial properties over time. These visual events may lead to objects falling out of our visual awareness, but can also lead to unnoticed changes, such as undetected object replacements and positional exchanges. Current visual memory models do not predict which visual changes are likely to be the most difficult to detect. We examine the accuracy with which switches (where two objects exchange locations) and substitutions (where one or two objects are replaced) are detected. Inferior performance for one-object substitutions versus two-objects switches, along with superior performance for two-object substitutions versus two-object switches was found. Our results are interpreted in terms of object file theory, trade-offs between diffused and localized attention, and net visual change.

  17. Fast flexoelectric switching in a cholesteric liquid crystal cell with surface-localized polymer network

    International Nuclear Information System (INIS)

    Kim, Sang Hwa; Shi, Lei; Chien, Liang-Chy

    2009-01-01

    We developed an electro-optical device based on the flexoelectric effect of a polymer-stabilized cholesteric liquid crystal with a uniform lying helix. Using a dual-frequency switchable nematic, a small amount of chiral dopant and a small amount of phase-separated polymer localized at the substrate surfaces, we were able to create a device that operates in both the amplitude (flexoelectric) and phase (dielectric) modes. Using a high-frequency voltage we were able to suppress the phase mode and preserve the amplitude mode.

  18. Fast-switching initially-transparent liquid crystal light shutter with crossed patterned electrodes

    Directory of Open Access Journals (Sweden)

    Joon Heo

    2015-04-01

    Full Text Available We propose an initially transparent light shutter using polymer-networked liquid crystals with crossed patterned electrodes. The proposed light shutter is switchable between the transparent and opaque states, and it exhibits a fast response time and a low operating voltage. In the transparent state, the light shutter has high transmittance; in the opaque state, it can block the background image and provides black color. We expect that the proposed light shutter can be applied to see-through displays and smart windows.

  19. Markov Switching Model for Quick Detection of Event Related Desynchronization in EEG

    Directory of Open Access Journals (Sweden)

    Giuseppe Lisi

    2018-02-01

    Full Text Available Quick detection of motor intentions is critical in order to minimize the time required to activate a neuroprosthesis. We propose a Markov Switching Model (MSM to achieve quick detection of an event related desynchronization (ERD elicited by motor imagery (MI and recorded by electroencephalography (EEG. Conventional brain computer interfaces (BCI rely on sliding window classifiers in order to perform online continuous classification of the rest vs. MI classes. Based on this approach, the detection of abrupt changes in the sensorimotor power suffers from an intrinsic delay caused by the necessity of computing an estimate of variance across several tenths of a second. Here we propose to avoid explicitly computing the EEG signal variance, and estimate the ERD state directly from the voltage information, in order to reduce the detection latency. This is achieved by using a model suitable in situations characterized by abrupt changes of state, the MSM. In our implementation, the model takes the form of a Gaussian observation model whose variance is governed by two latent discrete states with Markovian dynamics. Its objective is to estimate the brain state (i.e., rest vs. ERD given the EEG voltage, spatially filtered by common spatial pattern (CSP, as observation. The two variances associated with the two latent states are calibrated using the variance of the CSP projection during rest and MI, respectively. The transition matrix of the latent states is optimized by the “quickest detection” strategy that minimizes a cost function of detection latency and false positive rate. Data collected by a dry EEG system from 50 healthy subjects, was used to assess performance and compare the MSM with several logistic regression classifiers of different sliding window lengths. As a result, the MSM achieves a significantly better tradeoff between latency, false positive and true positive rates. The proposed model could be used to achieve a more reactive and

  20. Detection of trans-acting factors for hemoglobin switching by cell fusions

    International Nuclear Information System (INIS)

    Broyles, R.H.; Palmer, J.C.; Smith, D.J.; Ramseyer, T.H.

    1986-01-01

    The authors have devised protocols for chemically fusing erythroid cells from amphibians of different developmental stages, so that we may study the short-term effects of trans-acting factors on globin gene expression. The authors are performing both homospecifc (Rana x Rana) and heterospecific (Rana x Xenopus) fusions; and they are detecting the expression of specific globin genes with selective radioactive labeling ( 35 S-methionine is incorporated only into adult globins), polyacrylamide gel electrophoresis, monospecific antisera, and cDNA probes that are species-and developmental stage-specific. Their results indicate that: (1) there are factors in tadpole erythroblasts that can reactivate adult Hb synthesis in mature, synthetically-inactive adult RBCs; (2) there are factors in tadpole erythroblasts that can reactivate tadpole globin genes in adult RBCs; and (3) there are factors in adult erythroid cells that apparently activate adult globin genes in tadpole RBCs. These results suggests that erythroid cells from animals of different developmental stages possess different sets of globin gene-specific trans-acting factors which can be studied with a system that exhibits normal developmental Hb switching

  1. An ultra-sensitive method for the analysis of perfluorinated alkyl acids in drinking water using a column switching high-performance liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Dasu, Kavitha; Nakayama, Shoji F; Yoshikane, Mitsuha; Mills, Marc A; Wright, J Michael; Ehrlich, Shelley

    2017-04-21

    In epidemiological research, it has become increasingly important to assess subjects' exposure to different classes of chemicals in multiple environmental media. It is a common practice to aliquot limited volumes of samples into smaller quantities for specific trace level chemical analyses. A novel method was developed for the determination of 14 perfluorinated alkyl acids (PFAAs) in small volumes (10mL) of drinking water using off-line solid phase extraction (SPE) pre-treatment followed by on-line pre-concentration on a WAX column before analysis on column-switching high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). In general, large volumes (100-1000mL) have been used for the analysis of PFAAs in drinking water. The current method requires approximately 10mL of drinking water concentrated by using an SPE cartridge and eluted with methanol. A large volume injection of the extract was introduced on to a column-switching HPLC-MS/MS using a mix-mode SPE column for the trace level analysis of PFAAs in water. The recoveries for most of the analytes in the fortified laboratory blanks ranged from 73±14% to 128±5%. The lowest concentration minimum reporting levels (LCMRL) for the 14 PFAAs ranged from 0.59 to 3.4ng/L. The optimized method was applied to a pilot-scale analysis of a subset of drinking water samples from an epidemiological study. These samples were collected directly from the taps in the households of Ohio and Northern Kentucky, United States and the sources of drinking water samples are both surface water and ground water, and supplied by different water distribution facilities. Only five PFAAs, perfluoro-1-butanesulfonic acid (PFBS), perfluoro-1- -hexanesulfonic acid (PFHxS), perfluoro-1-octanesulfonic acid (PFOS), perfluoro-n-heptanoic acid (PFHpA) and perfluoro-n-octanoic acid (PFOA) are detected above the LCMRL values. The median concentrations of these five PFAAs detected in the samples was ≤4.1ng/L with PFOS at 7.6ng

  2. Improving inertial Pedestrian Dead-Reckoning by detecting unmodified switched-on lamps in buildings.

    Science.gov (United States)

    Jiménez, Antonio R; Zampella, Francisco; Seco, Fernando

    2014-01-03

    This paper explores how inertial Pedestrian Dead-Reckoning (PDR) location systems can be improved with the use of a light sensor to measure the illumination gradients created when a person walks under ceiling-mounted unmodified indoor lights. The process of updating the inertial PDR estimates with the information provided by light detections is a new concept that we have named Light-matching (LM). The displacement and orientation change of a person obtained by inertial PDR is used by the LM method to accurately propagate the location hypothesis, and vice versa; the LM approach benefits the PDR approach by obtaining an absolute localization and reducing the PDR-alone drift. Even from an initially unknown location and orientation, whenever the person passes below a switched-on light spot, the location likelihood is iteratively updated until it potentially converges to a unimodal probability density function. The time to converge to a unimodal position hypothesis depends on the number of lights detected and the asymmetries/irregularities of the spatial distribution of lights. The proposed LM method does not require any intensity illumination calibration, just the pre-storage of the position and size of all lights in a building, irrespective of their current on/off state. This paper presents a detailed description of the light-matching concept, the implementation details of the LM-assisted PDR fusion scheme using a particle filter, and several simulated and experimental tests, using a light sensor-equipped Galaxy S3 smartphone and an external foot-mounted inertial sensor. The evaluation includes the LM-assisted PDR approach as well as the fusion with other signals of opportunity (WiFi, RFID, Magnetometers or Map-matching) in order to compare their contribution in obtaining high accuracy indoor localization. The integrated solution achieves a localization error lower than 1 m in most of the cases.

  3. Improving Inertial Pedestrian Dead-Reckoning by Detecting Unmodified Switched-on Lamps in Buildings

    Directory of Open Access Journals (Sweden)

    Antonio R. Jiménez

    2014-01-01

    Full Text Available This paper explores how inertial Pedestrian Dead-Reckoning (PDR location systems can be improved with the use of a light sensor to measure the illumination gradients created when a person walks under ceiling-mounted unmodified indoor lights. The process of updating the inertial PDR estimates with the information provided by light detections is a new concept that we have named Light-matching (LM. The displacement and orientation change of a person obtained by inertial PDR is used by the LM method to accurately propagate the location hypothesis, and vice versa; the LM approach benefits the PDR approach by obtaining an absolute localization and reducing the PDR-alone drift. Even from an initially unknown location and orientation, whenever the person passes below a switched-on light spot, the location likelihood is iteratively updated until it potentially converges to a unimodal probability density function. The time to converge to a unimodal position hypothesis depends on the number of lights detected and the asymmetries/irregularities of the spatial distribution of lights. The proposed LM method does not require any intensity illumination calibration, just the pre-storage of the position and size of all lights in a building, irrespective of their current on/off state. This paper presents a detailed description of the light-matching concept, the implementation details of the LM-assisted PDR fusion scheme using a particle filter, and several simulated and experimental tests, using a light sensor-equipped Galaxy S3 smartphone and an external foot-mounted inertial sensor. The evaluation includes the LM-assisted PDR approach as well as the fusion with other signals of opportunity (WiFi, RFID, Magnetometers or Map-matching in order to compare their contribution in obtaining high accuracy indoor localization. The integrated solution achieves a localization error lower than 1 m in most of the cases.

  4. Detection of hydrogen buildup in initially pure nonhydrogenous liquids

    International Nuclear Information System (INIS)

    McNeany, S.R.; Jenkins, J.D.

    1978-12-01

    A technique for monitoring hydrogen buildup in initially pure nonhydrogenous liquids is described in this report. The detection method is based upon the neutron-moderating properties of hydrogen. The analysis leading to the selection and design of a hydrogen-monitoring device is described. An experimental mockup of the device was then constructed and tested for hydrogen sensitivity. A hot cell was used for these tests. A device proved capable of measuring hydrogen concentrations in the range of 0 to 13.0 x 10 27 atoms/m 3 , with an accuracy of about 1.0 x 10 27 atoms/m 3 . A typical measurement can be made in 3 to 5 min. The experimental results confirmed the sensitivities predicted by the analysis and demonstrated that such a device would be practical for hydrogen concentration measurements for criticality control in an HTGR fuel refabrication plant

  5. Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection.

    Science.gov (United States)

    Heshka, Nicole E; Hager, Darcy B

    2015-12-10

    A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate interferences, a two dimensional column configuration is used, with a Deans switch employed to transfer hydrogen sulfide from the first to the second column (heart-cutting). Liquid crude samples are first separated on a dimethylpolysiloxane column, and light gases are heart-cut and further separated on a bonded porous layer open tubular (PLOT) column that is able to separate hydrogen sulfide from other light sulfur species. Hydrogen sulfide is then detected with a sulfur chemiluminescence detector, adding an additional layer of selectivity. Following separation and detection of hydrogen sulfide, the system is backflushed to remove the high-boiling hydrocarbons present in the crude samples and to preserve chromatographic integrity. Dissolved hydrogen sulfide has been quantified in liquid samples from 1.1 to 500 ppm, demonstrating wide applicability to a range of samples. The method has also been successfully applied for the analysis of gas samples from crude oil headspace and process gas bags, with measurement from 0.7 to 9,700 ppm hydrogen sulfide.

  6. Comparison of ultraviolet detection and charged aerosol detection methods for liquid-chromatographic determination of protoescigenin.

    Science.gov (United States)

    Filip, Katarzyna; Grynkiewicz, Grzegorz; Gruza, Mariusz; Jatczak, Kamil; Zagrodzki, Bogdan

    2014-01-01

    Escin, a complex mixture of pentacyclic triterpene saponins obtained from horse chestnut seeds extract (HCSE; Aesculus hippocastanum L.), constitutes a traditional herbal active substance of preparations (drugs) used for a treatment of chronic venous insufficiency and capillary blood vessel leakage. A new approach to exploitation of pharmacological potential of this saponin complex has been recently proposed, in which the β-escin mixture is perceived as a source of a hitherto unavailable raw material, pentacyclic triterpene aglycone-protoescigenin. Although many liquid chromatography methods are described in the literature for saponins determination, analysis of protoescigenin is barely mentioned. In this work, a new ultra-high performance liquid chromatography (UHPLC) method developed for protoescigenin quantification has been described. CAD (charged aerosol detection), as a relatively new detection method based on aerosol charging, has been applied in this method as an alternative to ultraviolet (UV) detection. The influence of individual parameters on CAD response and sensitivity was studied. The detection was performed using CAD and UV (200 nm) simultaneously and the results were compared with reference to linearity, accuracy, precision and limit of detection.

  7. Nonlinear-Based MEMS Sensors and Active Switches for Gas Detection

    KAUST Repository

    Bouchaala, Adam M.

    2016-05-25

    The objective of this paper is to demonstrate the integration of a MOF thin film on electrostatically actuated microstructures to realize a switch triggered by gas and a sensing algorithm based on amplitude tracking. The devices are based on the nonlinear response of micromachined clamped-clamped beams. The microbeams are coated with a metal-organic framework (MOF), namely HKUST-1, to achieve high sensitivity. The softening and hardening nonlinear behaviors of the microbeams are exploited to demonstrate the ideas. For gas sensing, an amplitude-based tracking algorithm is developed to quantify the captured quantity of gas. Then, a MEMS switch triggered by gas using the nonlinear response of the microbeam is demonstrated. Noise analysis is conducted, which shows that the switch has high stability against thermal noise. The proposed switch is promising for delivering binary sensing information, and also can be used directly to activate useful functionalities, such as alarming.

  8. Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids.

    Science.gov (United States)

    Byers, Joshua C; Paulose Nadappuram, Binoy; Perry, David; McKelvey, Kim; Colburn, Alex W; Unwin, Patrick R

    2015-10-20

    Single molecule electrochemical detection (SMED) is an extremely challenging aspect of electroanalytical chemistry, requiring unconventional electrochemical cells and measurements. Here, SMED is reported using a "quad-probe" (four-channel probe) pipet cell, fabricated by depositing carbon pyrolytically into two diagonally opposite barrels of a laser-pulled quartz quadruple-barreled pipet and filling the open channels with electrolyte solution, and quasi-reference counter electrodes. A meniscus forms at the end of the probe covering the two working electrodes and is brought into contact with a substrate working electrode surface. In this way, a nanogap cell is produced whereby the two carbon electrodes in the pipet can be used to promote redox cycling of an individual molecule with the substrate. Anticorrelated currents generated at the substrate and tip electrodes, at particular distances (typically tens of nanometers), are consistent with the detection of single molecules. The low background noise realized in this droplet format opens up new opportunities in single molecule electrochemistry, including the use of ionic liquids, as well as aqueous solution, and the quantitative assessment and analysis of factors influencing redox cycling currents, due to a precisely known gap size.

  9. Magnetic relaxation switch and colorimetric detection of thrombin using aptamer-functionalized gold-coated iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liang Guohai; Cai Shaoyu; Zhang Peng [Department of Chemistry and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433 (China); Peng Youyuan [Department of Chemistry, Quanzhou Normal University, Quanzhou 362000 (China); Chen Hui; Zhang Song [Department of Chemistry and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433 (China); Kong Jilie, E-mail: jlkong@fudan.edu.cn [Department of Chemistry and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433 (China)

    2011-03-18

    We describe a sensitive biosensing system combining magnetic relaxation switch diagnosis and colorimetric detection of human {alpha}-thrombin, based on the aptamer-protein interaction induced aggregation of Fe{sub 3}O{sub 4}-Au nanoparticles. To demonstrate the concept, gold-coated iron oxide nanoparticle was synthesized by iterative reduction of HAuCl{sub 4} onto the dextran-coated Fe{sub 3}O{sub 4} nanoparticles. The resulting core-shell structure had a flowerlike shape with pretty narrow size distribution (referred to as 'nanorose'). The two aptamers corresponding to human {alpha}-thrombin were conjugated separately to two distinct nanorose populations. Once a solution containing human {alpha}-thrombin was introduced, the nanoroses switched from a well dispersed state to an aggregated one, leading to a change in the spin-spin relaxation time (T{sub 2}) as well as the UV-Vis absorption spectra of the solution. Thus the qualitative and quantitative detection method for human {alpha}-thrombin was established. The dual-mode detection is clearly advantageous in obtaining a more reliable result; the detection range is widened as well. By using the dual-mode detection method, a detectable T{sub 2} change is observed with 1.0 nM human {alpha}-thrombin, and the detection range is from 1.6 nM to 30.4 nM.

  10. Ionic liquid-dispersive liquid-liquid microextraction for the simultaneous determination of pesticides and metabolites in soils using high-performance liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Asensio-Ramos, María; Hernández-Borges, Javier; Borges-Miquel, Teresa M; Rodríguez-Delgado, Miguel Ángel

    2011-07-29

    In this work, an ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) procedure was developed for the extraction of a group of pesticides (carbendazim/benomyl, thiabendazole, fuberidazole, carbaryl and triazophos) and some of their key metabolites in soils (2-aminobenzimidazole, metabolite of carbendazim and 1-naphthol, metabolite of carbaryl) from aqueous soil extracts, using high performance liquid chromatography (HPLC) with fluorescence detection (FD). Analytes were previously extracted from four soils with different physicochemical properties (forestal, ornamental, garden and lapilli soils) by ultrasound-assisted extraction (USE). The IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF(6)]) and methanol (MeOH) were used as extraction and dispersion solvent, respectively, for the DLLME procedure. Factors affecting IL-DLLME (sample pH, IL amount, volume of dispersion solvent and sodium chloride percentage) were optimized by means of an experimental design, obtaining the most favorable results when using 117.5 mg of IL and 418 μL of MeOH to extract the compounds from the aqueous soil extracts at pH 5.20 containing 30% (w/v) NaCl. Calibration of the USE-IL-DLLME-HPLC-FD method was carried out for every type of soil and accuracy and precision studies were developed at two levels of concentration, finding that no significant differences existed between real and spiked concentrations (Student's t test). LODs achieved were in the low ng/g range. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Versatile lipid profiling by liquid chromatography–high resolution mass spectrometry using all ion fragmentation and polarity switching. Preliminary application for serum samples phenotyping related to canine mammary cancer

    Energy Technology Data Exchange (ETDEWEB)

    Gallart-Ayala, H., E-mail: laberca@oniris-nantes.fr [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), USC 1329 INRA Laboratoire d’Etude des résidus et Contaminants dans les Aliments (LABERCA), Site de la Chantrerie – CS50707, 44307 Nantes cedex 3 (France); Courant, F.; Severe, S.; Antignac, J.-P. [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), USC 1329 INRA Laboratoire d’Etude des résidus et Contaminants dans les Aliments (LABERCA), Site de la Chantrerie – CS50707, 44307 Nantes cedex 3 (France); Morio, F.; Abadie, J. [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), Cancers Animaux, Modèles pour la Recherche en Oncologie Comparée (AMaROC), Site de la Chantrerie–CS50707, 44307 Nantes cedex 3 (France); Le Bizec, B. [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), USC 1329 INRA Laboratoire d’Etude des résidus et Contaminants dans les Aliments (LABERCA), Site de la Chantrerie – CS50707, 44307 Nantes cedex 3 (France)

    2013-09-24

    Graphical abstract: -- Highlights: •Lipidomics, high resolution mass spectrometry, polarity switching, serum, canine mammary cancer. -- Abstract: Lipids represent an extended class of substances characterized by such high variety and complexity that makes their unified analyses by liquid chromatography coupled to either high resolution or tandem mass spectrometry (LC–HRMS or LC–MS/MS) a real challenge. In the present study, a new versatile methodology associating ultra high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC–HRMS/MS) have been developed for a comprehensive analysis of lipids. The use of polarity switching and “all ion fragmentation” (AIF) have been two action levels particularly exploited to finally permit the detection and identification of a multi-class and multi-analyte extended range of lipids in a single run. For identification purposes, both higher energy collision dissociation (HCD) and in-source CID (collision induced dissociation) fragmentation were evaluated in order to obtain information about the precursor and product ions in the same spectra. This approach provides both class-specific and lipid-specific fragments, enhancing lipid identification. Finally, the developed method was applied for differential phenotyping of serum samples collected from pet dogs developing spontaneous malignant mammary tumors and health controls. A biological signature associated with the presence of cancer was then successfully revealed from this lipidome analysis, which required to be further investigated and confirmed at larger scale.

  12. Liquid chromatographic determination with fluorescence detection of B6 vitamers and riboflavin in milk and pharmaceuticals

    International Nuclear Information System (INIS)

    Gatti, R.; Gioia, M.G.

    2005-01-01

    A simple, reliable and selective high performance liquid chromatographic method with fluorescence detection at different programmed wavelengths has been developed for the simultaneous analysis of B 6 vitamers (pyridoxal 5'-phosphate, 4-pyridoxic acid, pyridoxal, pyridoxine and pyridoxamine) and Vitamin B 2 in commercial vitaminized milk and in woman milk. The chromatographic separations were performed on a reversed phase octyl column by using a mobile phase consisting of sodium pentanesulfonate in 1% acetic acid-methanol-tetrahydrofuran under gradient elution conditions. The fluorescence intensity of pyridoxal 5'-phosphate was enhanced by post-column photochemical conversion, giving significantly different fluorescence spectra by a on-line photoreactor switched OFF and ON under irradiation at 254 nm. In addition, a simple and rapid method in isocratic conditions without the need of photochemical conversion was proposed for the analysis of Vitamin B 6 and Vitamin B 2 in pharmaceuticals. Linearity, precision, recovery, selectivity and sensitivity were found satisfactory for each analysed compound. Quantitation limits ranged from 26 to 240 fmol

  13. Identification and quantification of flavonoids in human urine samples by column switching liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, S. E.; Freese, R.; Cornett, Claus

    2000-01-01

    by column-switching, using the first column (a Zorbax 300SB C-3 column) for sample cleanup and eluting the heart-cut flavonoid fraction onto the second column (a Zorbax SE C-18 column) for separation and detection by ultraviolet and atmospheric pressure chemical ionization MS using single ion monitoring...

  14. Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

    2014-11-01

    An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Sodium leak detection system for liquid metal cooled nuclear reactors

    International Nuclear Information System (INIS)

    Modarres, D.

    1991-01-01

    This patent describes a device for detecting sodium leaks from a reactor vessel of a liquid sodium cooled nuclear reactor the reactor vessel being concentrically surrounded by a a containment vessel so as to define an airtight gap containing argon. It comprises: a light source for generating a first light beam, the first light beam having first and second predominant wavelengths, the first wavelength being substantially equal to an absorption line of sodium and the second wavelength being chosen such that it is not absorbed by sodium and argon; an optical multiplexer optically coupled to the light source; optically coupled to the multiplexer, each of the sensors being embedded in the containment vessel of the reactor, each of the sensors projecting the first light beam into the gap and collecting the first light beam after it has reflected off of a surface of the reactor vessel; a beam splitter optically coupled to each of the sensors through the multiplexer, the beam splitter splitting the first light beam into second and third light beams of substantially equal intensities; a first filter dispersed within a path of second light beam for filtering the second wavelength out of the third light beam; first and second detector beams disposed with in the paths of the second and third light beams so as to detect the intensities of the second and third light beams, respectively; and processing means connected to the first and second detector means for calculating the amount of the first wavelength which is absorbed when passing through the argon

  16. Electrochemical detection of dopamine using arrays of liquid-liquid micro-interfaces created within micromachined silicon membranes

    International Nuclear Information System (INIS)

    Berduque, Alfonso; Zazpe, Raul; Arrigan, Damien W.M.

    2008-01-01

    The detection of protonated dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at arrays of micro-interfaces between two immiscible electrolyte solutions (μITIES) is presented. Microfabricated porous silicon membranes (consisting of eight pores, 26.6 μm in radius and 500 μm pore-pore separation, in a hexagonal layout) were prepared by photolithographic and etching procedures. The membrane pores were fabricated with hydrophobic internal walls so that the organic phase filled the pores and created the liquid interface at the aqueous side of the membrane. These were used for harnessing the benefits of three-dimensional diffusion to the interface and for interface stabilisation. The liquid-liquid interface provides a simple method to overcome the major problem in the voltammetric detection of dopamine at solid electrodes due to the co-existence of ascorbate at higher concentrations. Selectivity for dopamine over ascorbate was achieved by the use of dibenzo-18-crown-6 (DB18C6) for the facilitated ion transfer of dopamine across the μITIES array. Under these conditions, the presence of ascorbate in excess did not interfere in the detection of dopamine and the lowest concentration detectable was ca. 0.5 μM. In addition, the drawback of current signal saturation (non-linear increase of the peak current with the concentration of dopamine) observed at conventional (millimetre-sized) liquid-liquid interfaces was overcome using the microfabricated porous membranes

  17. Toehold-mediated nonenzymatic amplification circuit on graphene oxide fluorescence switching platform for sensitive and homogeneous microRNA detection

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ru; Liao, Yuhui; Zhou, Xiaoming, E-mail: zhouxm@scnu.edu.cn; Xing, Da, E-mail: xingda@scnu.edu.cn

    2015-08-12

    A novel graphene oxide (GO) fluorescence switch-based homogenous system has been developed to solve two problems that are commonly encountered in conventional GO-based biosensors. First, with the assistance of toehold-mediated nonenzymatic amplification (TMNA), the sensitivity of this system greatly surpasses that of previously described GO-based biosensors, which are always limited to the nM range due to the lack of efficient signal amplification. Second, without enzymatic participation in amplification, the unreliability of detection resulting from nonspecific desorption of DNA probes on the GO surface by enzymatic protein can be avoided. Moreover, the interaction mechanism of the double-stranded TMNA products contains several single-stranded toeholds at two ends and GO has also been explored with combinations of atomic force microscopy imaging, zeta potential detection, and fluorescence assays. It has been shown that the hybrids can be anchored to the surface of GO through the end with more unpaired bases, and that the other end, which has weaker interaction with GO, can escape GO adsorption due to the robustness of the central dsDNA structures. We verified this GO fluorescence switch-based detection system by detecting microRNA 21, an overexpressed non-encoding gene in a variety of malignant cells. Rational design of the probes allowed the isothermal nonenzymatic reaction to achieve more than 100-fold amplification efficiency. The detection results showed that our strategy has a detection limit of 10 pM and a detection range of four orders of magnitude. - Highlights: • This paper explored the interaction mechanism of TMNA products with GO surface. • This homogeneous and isothermal system permits a detection limit of 10 pM for microRNA. • This nonenzymatic strategy can avoid nonspecific desorption caused by enzyme protein. • The interaction model can be used to explore the application ability of nonenzymatic circuit.

  18. Intensifying the density of a horizontal electric field to improve light efficiency in a fringe-field switching liquid crystal display

    Energy Technology Data Exchange (ETDEWEB)

    Yu, In Ho; Song, Il Sub; Lee, Ji Youn; Lee, Seung Hee [Research Center of Advanced Material Development, School of Advanced Materials Engineering, Chonbuk National University, Chonju, Chonbuk 561-756 (Korea, Republic of)

    2006-06-07

    The transmittance in fringe-field switching liquid crystal (LC) displays, which show a wide viewing angle, is dependent on the position along the electrode position. The reason for this is that the dielectric torque (and hence the twist angle) varies with position. This effect depends on the type of LC: a display using an LC with positive dielectric anisotropy has less transmittance than one with negative dielectric anisotropy. Furthermore, the transmittance decreases with decreasing cell gap. The difference between the LC types can be reduced and the transmittance can be improved greatly even for a low cell gap by optimizing the electrode structure to enhance the region of in-plane twist.

  19. Fault Detection and Location by Static Switches in Microgrids Using Wavelet Transform and Adaptive Network-Based Fuzzy Inference System

    Directory of Open Access Journals (Sweden)

    Ying-Yi Hong

    2014-04-01

    Full Text Available Microgrids are a highly efficient means of embedding distributed generation sources in a power system. However, if a fault occurs inside or outside the microgrid, the microgrid should be immediately disconnected from the main grid using a static switch installed at the secondary side of the main transformer near the point of common coupling (PCC. The static switch should have a reliable module implemented in a chip to detect/locate the fault and activate the breaker to open the circuit immediately. This paper proposes a novel approach to design this module in a static switch using the discrete wavelet transform (DWT and adaptive network-based fuzzy inference system (ANFIS. The wavelet coefficient of the fault voltage and the inference results of ANFIS with the wavelet energy of the fault current at the secondary side of the main transformer determine the control action (open or close of a static switch. The ANFIS identifies the faulty zones inside or outside the microgrid. The proposed method is applied to the first outdoor microgrid test bed in Taiwan, with a generation capacity of 360.5 kW. This microgrid test bed is studied using the real-time simulator eMegaSim developed by Opal-RT Technology Inc. (Montreal, QC, Canada. The proposed method based on DWT and ANFIS is implemented in a field programmable gate array (FPGA by using the Xilinx System Generator. Simulation results reveal that the proposed method is efficient and applicable in the real-time control environment of a power system.

  20. Proposed Suitable Methods to Detect Transient Regime Switching to Improve Power Quality with Wavelet Transform

    Directory of Open Access Journals (Sweden)

    Javad Safaee Kuchaksaraee

    2016-10-01

    Full Text Available The increasing consumption of electrical energy and the use of non-linear loads that create transient regime states in distribution networks is increasing day by day. This is the only reason due to which the analysis of power quality for energy sustainability in power networks has become more important. Transients are often created by energy injection through switching or lightning and make changes in voltage and nominal current. Sudden increase or decrease in voltage or current makes characteristics of the transient regime. This paper shed some lights on the capacitor bank switching, which is one of the main causes for oscillatory transient regime states in the distribution network, using wavelet transform. The identification of the switching current of capacitor bank and the internal fault current of the transformer to prevent the unnecessary outage of the differential relay, it propose a new smart method. The accurate performance of this method is shown by simulation in EMTP and MATLAB (matrix laboratory software.

  1. Liquid chromatographic separation and indirect detection of non-absorbing aliphatic compounds using m-nitrophenol as a detection agent

    International Nuclear Information System (INIS)

    Lee, Seung Seok; Kang, Sam Woo; Moon, Young Ja

    1991-01-01

    m-Nitrophenol(m-NP) was a detection agent for the use of the detection and separation of non-absorbing compounds such as aliphatic acids, alcohols, amines and tetraalkylammonium salts by indirect photometric detection in reversed-phase liquid chromatography. Response of samples was investigated to the several factors such as pH, temperature, and concentration of MeOH as well as concentration of detection reagent in mobile phase. The separation of several mixtures were attempted under optimum condition. (Author)

  2. Failure detection of liquid cooled electronics in sealed packages. [in airborne information management system

    Science.gov (United States)

    Hoadley, A. W.; Porter, A. J.

    1991-01-01

    The theory and experimental verification of a method of detecting fluid-mass loss, expansion-chamber pressure loss, or excessive vapor build-up in NASA's Airborne Information Management System (AIMS) are presented. The primary purpose of this leak-detection method is to detect the fluid-mass loss before the volume of vapor on the liquid side causes a temperature-critical part to be out of the liquid. The method detects the initial leak after the first 2.5 pct of the liquid mass has been lost, and it can be used for detecting subsequent situations including the leaking of air into the liquid chamber and the subsequent vapor build-up.

  3. [Research on shortwave NIR spectroscopy and its application to in situ flammable liquid detection].

    Science.gov (United States)

    Wu, Juan; Du, Zhen-hui; Liu, Jin; Xu, Ke-zin

    2008-09-01

    Fast, accurate and highly effective detection in situ was important to the control of illegal transportation and the use of liquid state dangerous goods. The present article used the strong penetrability of the shortwave near-infrared ray to the packing material and liquid and measured the absorption spectra of some flammable liquids such as the absolute ethyl alcohol, absolute methanol, ammonia, turpentine, gasoline, diesel oil, petroleum etc and the partial liquors in the short wavelength region of NIR (667-1000 nm). The primitive spectral data were standardized and compressed, and then, the characteristic wavelength of the absorption spectra was analyzed using the SPSS statistics software. A math model for flammable liquid distinction was established based on the designated characteristic wavelength and can correctly detect flammable liquid using the absorbency of 3 wavelengths (881, 935 and 981 nm). According to the above the authors may construct the inexpensive spectrum instrument to check the flammable liquid non-destructively in situ.

  4. Impact of injection solvent composition on protein identification in column-switching chip-liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Houbart, V; Cobraiville, G; Nys, G; Merville, M-P; Fillet, M

    2016-05-06

    In shotgun proteomics, the gold standard technique is reversed-phase liquid chromatography coupled to mass spectrometry. Many researches have been carried out to study the effects on identification performances of chromatographic parameters such as the stationary phase and column dimensions, mobile phase composition and flow rate, as well as the gradient slope and length. However, little attention is usually paid to the injection solvent composition. In this study, we investigated the effect of the injection solvent on protein identification parameters (number of distinct peptides, amino acid coverage and MS/MS search score) as well as sensitivity. Tryptic peptides from six different proteins, covering a wide range of physicochemical properties, were employed as training set. Design of experiments was employed as a tool to highlight the factors related to the composition of the injection solvent that significantly influenced the obtained results. Optimal results for the training set were applied to analysis of more complex samples. The experiments pointed out optimising the composition of the injection solvent had a strong beneficial effect on all the considered responses. On the basis of these results, an approach to determine optimal conditions was proposed to maximise the protein identification performances and detection sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Simple and rapid determination of zaltoprofen in human plasma by manual-shaking-assisted dispersive liquid-liquid microextraction followed by liquid chromatography with ultraviolet detection.

    Science.gov (United States)

    Han, Se Young; Jeong, Kyung Min; Yoo, Da Eun; Jin, Yan; Kim, Eun Mi; Kim, Su Hyun; Lee, Seok-Yong; Kim, Se-Hyung; Zhao, Jing; Lee, Jeongmi

    2017-10-01

    A readily applicable method was developed to determine the concentration level of zaltoprofen, a non-steroidal antiinflammatory drug from the propionic acid family, in human plasma. This method is based on manual-shaking-assisted dispersive liquid-liquid microextraction coupled with liquid chromatography with ultraviolet detection. Factors affecting the extraction efficiency were screened and optimized by experimental design using fractional factorial and central composite designs, respectively. Optimal conditions were: 220 μL of C 2 H 4 Cl 2 (extraction solvent), 5 mL of 3.75% w/v NaCl aqueous solution at pH 2.0, and manual shaking for 13 s (65 times). The resulting extraction method yielded a reasonable enrichment factor of 18.0 (±0.6, n = 3) and extraction recovery of 86.0% (±3.3%, n = 3). The established method was validated for selectivity, linearity, precision, accuracy, matrix effect, recovery, dilution integrity, and stability, and it met the acceptable criteria for all of the tested parameters. Specifically, the method was linear in the range of 0.16-50.0 mg/L, precise (liquid-liquid extraction or non-specific protein precipitation, our method allows the simple, rapid, and efficient determination of zaltoprofen using the most affordable analytical instrument, liquid chromatography with ultraviolet detection. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Simultaneous determination of carboprost methylate and its active metabolite carboprost in dog plasma by liquid chromatography-tandem mass spectrometry with positive/negative ion-switching electrospray ionization and its application to a pharmacokinetic study.

    Science.gov (United States)

    Yin, Lei; Meng, Xiangjun; Zhou, Xiaotong; Zhang, Tinglan; Sun, Heping; Yang, Zhichao; Yang, Bo; Xiao, Ning; Fawcett, J Paul; Yang, Yan; Gu, Jingkai

    2015-08-15

    A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method using positive/negative electrospray ionization (ESI) switching for the simultaneous quantitation of carboprost methylate and carboprost in dog plasma has been developed and validated. After screening, the esterase inhibitor, dichlorvos was added to the whole blood at a ratio of 1:99 (v/v) to stabilize carboprost methylate during blood collection, sample storage and LLE. Indomethacin was added to plasma to inhibit prostaglandins synthesis after sampling. After liquid-liquid extraction of 500μL plasma with ethyl ether-dichloromethane (75:25, v/v), analytes and internal standard (IS), alprostadil-d4, were chromatographed on a CAPCELL PAK Phenyl column (150×2.0mm, 5μm) using acetonitrile-5mM ammonium acetate as mobile phase. Carboprost methylate was detected by positive ion electrospray ionization followed by multiple reaction monitoring (MRM) of the transition at m/z 400.5→329.3; the carboprost and IS were detected by negative ion electrospray ionization followed by MRM of the transitions at m/z 367.2→323.2, and 357.1→321.2, respectively. The method was linear for both analytes in the concentration range 0.05-30ng/mL with intra- and inter-day precisions (as relative standard deviation) of ≤6.75% and accuracy (as relative error) of ≤7.21% and limit of detection (LOD) values were 10 and 20pg/mL, respectively. The method was successfully applied to a pharmacokinetic study of the analytes in beagle dogs after intravaginal administration of a suppository containing 0.5mg carboprost methylate. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. The observation of valence band change on resistive switching of epitaxial Pr0.7Ca0.3MnO3 film using removable liquid electrode

    Science.gov (United States)

    Lee, Hong-Sub; Park, Hyung-Ho

    2015-12-01

    The resistive switching (RS) phenomenon in transition metal oxides (TMOs) has received a great deal of attention for non-volatile memory applications. Various RS mechanisms have been suggested as to explain the observed RS characteristics. Many reports suggest that changes of interface and the role of oxygen vacancies originate in RS phenomena; therefore, in this study, we use a liquid drop of mercury as the top electrode (TE), epitaxial Pr0.7Ca0.3MnO3 (PCMO) (110) film of the perovskite manganite family for RS material, and an Nb-doped (0.7 at. %) SrTiO3 (100) single crystal as the substrate to observe changes in the interface between the TE and TMOs. The use of removable liquid electrode Hg drop as TE not only enables observation of the RS characteristic as a bipolar RS curve (counterclockwise) but also facilitates analysis of the valence band of the PCMO surface after resistive switching via photoelectron spectroscopy. The observed I-V behaviors of the low and high resistance states (HRS) are explained with an electrochemical migration model in PCMO film where accumulated oxygen vacancies at the interface between the Hg TE and PCMO (110) surface induce the HRS. The interpreted RS mechanism is directly confirmed via valence band spectrum analysis.

  8. 75 FR 4134 - Pipeline Safety: Leak Detection on Hazardous Liquid Pipelines

    Science.gov (United States)

    2010-01-26

    .... PHMSA-2009-0421] Pipeline Safety: Leak Detection on Hazardous Liquid Pipelines AGENCY: Pipeline and... INFORMATION: Background Pipeline leak detection is one of the many layers of protection in PHMSA's approach to... of these interconnected layers of protections, including advances in leak detection systems. These...

  9. Assay for dihydroorotase using high-performance liquid chromatography with radioactivity detection

    International Nuclear Information System (INIS)

    Mehdi, S.; Wiseman, J.S.

    1989-01-01

    An assay for measuring dihydroorotase activity was devised. Radiolabeled substrate and product were separated by high-performance liquid chromatography using a reverse-phase column with ion-pairing, and the radioactivity was quantitated by flow detection

  10. Silicon MEMS for Detection of Liquid and Solid Fronts

    NARCIS (Netherlands)

    Wei, J.

    2010-01-01

    High-precision manipulation of small-size objects is an attractive and challenging topic for both industrial production and fundamental scientific research. The capability of monitoring micro-samples during handling is essential to the accuracy and efficiency of a handling system for both liquid and

  11. Safety circuit for detecting conducting liquid in a cell under surveillance

    International Nuclear Information System (INIS)

    Kazandjoglou, J.

    1984-01-01

    The present invention can be applied for the surveillance of gloveboxes for which it is imperious to detect any water leak as soon as it occurs accidently. The safety and detection circuit comprises a liquid detector which consists of two electrodes. Each electrode has two connector wires connected in an electronic circuit. This circuit includes a first MOSFET which is non-conducting when no liquid or no failure in its connections is present. This first transistor is connected to a second MOSFET, conducting when no liquid or no failure in its connections is present, delivers current to an alarm, signaling and monitoring relay of a cell under surveillance [fr

  12. A detection and control method of resin liquid-level of stereolithography apparatus

    Science.gov (United States)

    Wang, Yiqing; Zhao, Wanhua; Shi, Leping; Lu, Bingheng

    2008-12-01

    A set of laser detecting system for liquid-level with inclination measurement-based high-resolution and a sinking-block device are developed to detect and control the liquid-level of Stereolithography Apparatus precisely. A brightness-variable laser source is adopted to eliminate the computational error of divider, a closed-loop circuit is set to measure the terminal voltage directly which proportional to the output current of PSD, and hence the position of laser beam can be indicated accurately. A sinking-block device is employed to control the liquid level. The precise calibration result of this detecting device indicates that the resolution of the liquid-level detection can reach +/-1.5µm. Compared with overflow liquid-level control, this liquid-level control device of sinking-block style can allow the liquid-level wave reduce from +/-45µm to +/-15µm. This system works stable with the high precision and antijamming ability. It has applied successfully in Stereolithography Apparatus.

  13. Detection of {sup 8}B solar neutrinos in liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Ianni, A [Laboratori Nazionali del Gran Sasso and INFN, I-67010 Assergi (Italy); Montanino, D [Dipartimento di Fisica, Universita' di Lecce and INFN, I-73100 Lecce (Italy); Villante, F L [Dipartimento di Fisica, Universita di Ferrara and INFN, I-44100 Ferrara (Italy)

    2006-05-15

    We show that liquid organic scintillator detectors (e. g., KamLAND and Borexino) can measure the {sup 8}B solar neutrino flux by means of the {nu}{sub e} charged current interaction with the {sup 13}C nuclei naturally contained in the scintillators. The neutrino events can be identified by exploiting the time and space coincidence with the subsequent decay of the produced {sup 13}N nuclei.

  14. Fast neutron detection with 6Li-loaded liquid scintillator

    Science.gov (United States)

    Fisher, B. M.; Abdurashitov, J. N.; Coakley, K. J.; Gavrin, V. N.; Gilliam, D. M.; Nico, J. S.; Shikhin, A. A.; Thompson, A. K.; Vecchia, D. F.; Yants, V. E.

    2011-08-01

    We report on the development of a fast neutron detector using a liquid scintillator doped with enriched 6Li. The lithium was introduced in the form of an aqueous LiCl micro-emulsion with a di-isopropylnaphthalene-based liquid scintillator. A 6Li concentration of 0.15% by weight was obtained. A 125 mL glass cell was filled with the scintillator and irradiated with fission-source neutrons. Fast neutrons may produce recoil protons in the scintillator, and those neutrons that thermalize within the detector volume can be captured on the 6Li. The energy of the neutron may be determined by the light output from recoiling protons, and the capture of the delayed thermal neutron reduces background events. In this paper, we discuss the development of this 6Li-loaded liquid scintillator, demonstrate the operation of it in a detector, and compare its efficiency and capture lifetime with Monte Carlo simulations. Data from a boron-loaded plastic scintillator were acquired for comparison. We also present a pulse-shape discrimination method for differentiating between electronic and nuclear recoil events based on the Matusita distance between a normalized observed waveform and nuclear and electronic recoil template waveforms. The details of the measurements are discussed along with specifics of the data analysis and its comparison with the Monte Carlo simulation.

  15. [Applications of atomic emission spectrum from liquid electrode discharge to metal ion detection].

    Science.gov (United States)

    Mao, Xiu-Ling; Wu, Jian; Ying, Yi-Bin

    2010-02-01

    The fast and precise detection of metal ion is an important research project concerning studies in diverse academic fields and different kinds of detecting technologies. In the present paper, the authors review the research on atomic emission spectrum based on liquid electrode discharge and its applications in the detection of metal ion. In the first part of this paper the principles and characteristics of the methods based on electrochemistry and spectroscopy were introduced. The methods of ion-selective electrode (ISE), anodic stripping voltammetry, atomic emission spectrum and atomic absorption spectrum were included in this part and discussed comparatively. Then the principles and characteristics of liquid electrode spectra for metal ion detection were introduced. The mechanism of the plasma production and the characteristics of the plasma spectrum as well as its advantages compared with other methods were discussed. Secondly, the authors divided the discharge system into two types and named them single liquid-electrode discharge and double-liquid electrode respectively, according to the number of the liquid electrode and the configuration of the discharge system, and the development as well as the present research status of each type was illustrated. Then the characteristics and configurations of the discharge systems including ECGD, SCGD, LS-APGD and capillary discharge were discussed in detail as examples of the two types. By taking advantage of the technology of atomic emission spectrum based on liquid electrode discharge, the detecting limit of heavy metals such as copper, mercury and argent as well as active metal ions including sodium, potass and magnesium can achieve microg x L(-1). Finally, the advantages and problems of the liquid-electrode discharge applied in detection of metal ion were discussed. And the applications of the atomic emission spectrum based on liquid electrode discharge were prospected.

  16. Versatile lipid profiling by liquid chromatography-high resolution mass spectrometry using all ion fragmentation and polarity switching. Preliminary application for serum samples phenotyping related to canine mammary cancer.

    Science.gov (United States)

    Gallart-Ayala, H; Courant, F; Severe, S; Antignac, J-P; Morio, F; Abadie, J; Le Bizec, B

    2013-09-24

    Lipids represent an extended class of substances characterized by such high variety and complexity that makes their unified analyses by liquid chromatography coupled to either high resolution or tandem mass spectrometry (LC-HRMS or LC-MS/MS) a real challenge. In the present study, a new versatile methodology associating ultra high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC-HRMS/MS) have been developed for a comprehensive analysis of lipids. The use of polarity switching and "all ion fragmentation" (AIF) have been two action levels particularly exploited to finally permit the detection and identification of a multi-class and multi-analyte extended range of lipids in a single run. For identification purposes, both higher energy collision dissociation (HCD) and in-source CID (collision induced dissociation) fragmentation were evaluated in order to obtain information about the precursor and product ions in the same spectra. This approach provides both class-specific and lipid-specific fragments, enhancing lipid identification. Finally, the developed method was applied for differential phenotyping of serum samples collected from pet dogs developing spontaneous malignant mammary tumors and health controls. A biological signature associated with the presence of cancer was then successfully revealed from this lipidome analysis, which required to be further investigated and confirmed at larger scale. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Real-Time, Non-Intrusive Detection of Liquid Nitrogen in Liquid Oxygen at High Pressure and High Flow

    Science.gov (United States)

    Singh, Jagdish P.; Yueh, Fang-Yu; Kalluru, Rajamohan R.; Harrison, Louie

    2012-01-01

    An integrated fiber-optic Raman sensor has been designed for real-time, nonintrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressures and high flow rates in order to monitor the quality of LOX used during rocket engine ground testing. The integrated sensor employs a high-power (3-W) Melles Griot diode-pumped, solid-state (DPSS), frequency-doubled Nd:YAG 532- nm laser; a modified Raman probe that has built-in Raman signal filter optics; two high-resolution spectrometers; and photomultiplier tubes (PMTs) with selected bandpass filters to collect both N2 and O2 Raman signals. The PMT detection units are interfaced with National Instruments Lab- VIEW for fast data acquisition. Studies of sensor performance with different detection systems (i.e., spectrometer and PMT) were carried out. The concentration ratio of N2 and O2 can be inferred by comparing the intensities of the N2 and O2 Raman signals. The final system was fabricated to measure N2 and O2 gas mixtures as well as mixtures of liquid N2 and LOX

  18. Simultaneous determination of asperosaponin VI and its active metabolite hederagenin in rat plasma by liquid chromatography-tandem mass spectrometry with positive/negative ion-switching electrospray ionization and its application in pharmacokinetic study.

    Science.gov (United States)

    Zhu, He; Ding, Li; Shakya, Shailendra; Qi, Xiemin; Hu, Linlin; Yang, Xiaolin; Yang, Zhonglin

    2011-11-15

    A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method operated in the positive/negative electrospray ionization (ESI) switching mode has been developed and validated for the simultaneous determination of asperosaponin VI and its active metabolite hederagenin in rat plasma. After addition of internal standards diazepam (for asperosaponin VI) and glycyrrhetic acid (for hederagenin), the plasma sample was deproteinized with acetonitrile, and separated on a reversed phase C18 column with a mobile phase of methanol (solvent A)-0.05% glacial acetic acid containing 10 mM ammonium acetate and 30 μM sodium acetate (solvent B) using gradient elution. The detection of target compounds was done in multiple reaction monitoring (MRM) mode using a tandem mass spectrometry equipped with positive/negative ion-switching ESI source. At the first segment, the MRM detection was operated in the positive ESI mode using the transitions of m/z 951.5 ([M+Na](+))→347.1 for asperosaponin VI and m/z 285.1 ([M+H](+))→193.1 for diazepam for 4 min, then switched to the negative ESI mode using the transitions of m/z 471.3 ([M-H](-))→471.3 for hederagenin and m/z 469.4 ([M-H](-))→425.4 for glycyrrhetic acid, respectively. The sodiated molecular ion [M+Na](+) at m/z 951.5 was selected as the precursor ion for asperosaponin VI, since it provided better sensitivity compared to the deprotonated and protonated molecular ions. Sodium acetate was added to the mobile phase to make sure that abundant amount of the sodiated molecular ion of asperosaponin VI could be produced, and more stable and intensive mass response of the product ion could be obtained. For the detection of hederagenin, since all of the mass responses of the fragment ions were very weak, the deprotonated molecular ion [M-H](-)m/z 471.3 was employed as both the precursor ion and the product ion. But the collision energy was still used for the MRM, in order to eliminate the influences induced by the interference

  19. Flipping the switch: Tools for detecting small molecule inhibitors of staphylococcal virulence

    Directory of Open Access Journals (Sweden)

    Cassandra L. Quave

    2014-12-01

    Full Text Available Through the expression of the accessory gene regulator (agr quorum sensing cascade, S. aureus is able to produce an extensive array of enzymes, hemolysins and immunomodulators essential to its ability to spread through the host tissues and cause disease. Many have argued for the discovery and development of quorum sensing inhibitors (QSIs to augment existing antibiotics as adjuvant therapies. Here, we discuss the state-of-the-art tools that can be used to conduct screens for the identification of such QSIs. Examples include fluorescent reporters, MS-detection of autoinducing peptide (AIP production, agar plate methods for detection of hemolysins and lipase, HPLC-detection of hemolysins from supernatants, and cell-toxicity assays for detecting damage (or relief thereof against human keratinocyte (HaCat cells. In addition to providing a description of these various approaches, we also discuss their amenability to low-, medium- and high-throughput screening efforts for the identification of novel QSIs.

  20. Evaluation of liquid biopsies for detection of emerging mutated genes in metastatic colorectal cancer.

    Science.gov (United States)

    Furuki, Hiroyasu; Yamada, Takeshi; Takahashi, Goro; Iwai, Takuma; Koizumi, Michihiro; Shinji, Seiichi; Yokoyama, Yasuyuki; Takeda, Kohki; Taniai, Nobuhiko; Uchida, Eiji

    2018-02-02

    Detection of gene mutations is important for planning molecular targeted therapy. Although most gene mutations are concordant between primary colon cancers and their liver metastases, new mutations can emerge in metastases. The liquid biopsy is a newly developed, gene analytic method to detect mutations in metastatic tumors. In this prospective study, we evaluated the applicability of liquid biopsies in the detection of mutations in primary and metastatic tumors. We included 22 patients with liver metastases from colorectal cancer and extracted DNA from primary colorectal tumors, metastatic liver tumors, and peripheral blood (liquid biopsy). Next-generation sequencing (NGS) and digital PCR were performed to detect mutations in these three sample types. We found a total of 36 different mutations in samples from primary tumors, liver metastases, and liquid biopsies using NGS. Twenty-eight of these mutations were found in all three types of samples, whereas liquid biopsy did not identify four mutations that had been found in both primary tumors and liver metastases, but did identify four mutations that were found in liver tumors but not in primary tumors. The sensitivity of liquid biopsies for detecting mutations in liver metastases was 64% (23/36) using NGS and 89% (32/36, P = 0.02) using dPCR. The specificities of NGS and dPCR were 100% (23/23) and 100% (32/32), respectively. Emerging mutations, which are not found in primary tumors, can be detected in their metastases and liquid biopsies. Copyright © 2018 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

  1. An Artificially Intelligent Physical Model-Checking Approach to Detect Switching-Related Attacks on Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    El Hariri, Mohamad [Florida Intl Univ., Miami, FL (United States); Faddel, Samy [Florida Intl Univ., Miami, FL (United States); Mohammed, Osama [Florida Intl Univ., Miami, FL (United States)

    2017-11-01

    Decentralized and hierarchical microgrid control strategies have lain the groundwork for shaping the future smart grid. Such control approaches require the cooperation between microgrid operators in control centers, intelligent microcontrollers, and remote terminal units via secure and reliable communication networks. In order to enhance the security and complement the work of network intrusion detection systems, this paper presents an artificially intelligent physical model-checking that detects tampered-with circuit breaker switching control commands whether, due to a cyber-attack or human error. In this technique, distributed agents, which are monitoring sectionalized areas of a given microgrid, will be trained and continuously adapted to verify that incoming control commands do not violate the physical system operational standards and do not put the microgrid in an insecure state. The potential of this approach has been tested by deploying agents that monitor circuit breakers status commands on a 14-bus IEEE benchmark system. The results showed the accuracy of the proposed framework in characterizing the power system and successfully detecting malicious and/or erroneous control commands.

  2. A molecular switch sensor for detection of PRSS1 genotype based on site-specific DNA cleavage of restriction endonuclease.

    Science.gov (United States)

    Liu, Qicai; Gao, Feng; Weng, Shaohuang; Peng, Huaping; Lin, Liqing; Zhao, Chengfei; Lin, Xinhua

    2015-01-01

    PRSS1 mutations or polymorphism in the peripheral blood of patients can be used as susceptible molecular markers to pancreatic cancer. A sensor for selective electrochemical detection of PRSS1 genotypes was developed based on site-specific DNA cleavage of restriction endonuclease EcoRI. A mercapto-modified hairpin probe was immobilized on a gold electrode. The probe's neck can be cleaved by EcoRI in the absence of rs10273639 C/C of PRSS1 genotype, but it cannot be cleaved in the presence of T/T. The difference in quantity of electric charge was monitored by biosensors before and after enzymatic cleavage. Electrochemical signals are generated by differential pulse voltammetry interrogation of methylene blue (MB) that quantitatively binds to surface-confined hairpin probe via electrostatic interactions. The results suggested this method had a good specificity in distinguishing PRSS1 genotypes. There was a good linear relationship between the charge and the logarithmic function of PRSS1 rs10273639 T/T type DNA concentration (current=120.6303+8.8512log C, R=0.9942). The detection limit was estimated at 0.5 fM. The molecular switch sensor has several advantages, and it is possible to qualitatively, quantitatively, and noninvasively detect PRSS1 genotypes in the blood of patients with pancreatic cancer. © 2015 by the Association of Clinical Scientists, Inc.

  3. Fast and sensitive method for detecting volatile species in liquids

    DEFF Research Database (Denmark)

    Trimarco, Daniel Bøndergaard; Pedersen, Thomas; Hansen, Ole

    2015-01-01

    the capabilities of this method, a CO-stripping experiment is performed on a polycrystalline platinum thin film, illustrating how the sniffer-chip system is capable of making a quantitative in situ measurement of ...This paper presents a novel apparatus for extracting volatile species from liquids using a “sniffer-chip.” By ultrafast transfer of the volatile species through a perforated and hydrophobic membrane into an inert carrier gas stream, the sniffer-chip is able to transport the species directly...... and the high sensitivity of a MIMS system. In this paper, the concept of the sniffer-chip is thoroughly explained and it is shown how it can be used to quantify hydrogen and oxygen evolution on a polycrystalline platinum thin film in situ at absolute faradaic currents down to ~30 nA. To benchmark...

  4. Organic Liquids-Responsive β-Cyclodextrin-Functionalized Graphene-Based Fluorescence Probe: Label-Free Selective Detection of Tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Huawen Hu

    2014-06-01

    Full Text Available In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB into the inner cavities of the β-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the β-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 μg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described.

  5. Slow-light enhanced optical detection in liquid-infiltrated photonic crystals

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard; Rishøj, Lars Søgaard; Steffensen, Henrik

    2007-01-01

    Slow-light enhanced optical detection in liquid-infiltrated photonic crystals is theoretically studied. Using a scattering-matrix approach and the Wigner–Smith delay time concept, we show that optical absorbance benefits both from slow-light phenomena as well as a high filling factor of the energy...... residing in the liquid. Utilizing strongly dispersive photonic crystal structures, we numerically demonstrate how liquid-infiltrated photonic crystals facilitate enhanced light–matter interactions, by potentially up to an order of magnitude. The proposed concept provides strong opportunities for improving...

  6. Facile and Cost-Effective Detection of Saxitoxin Exploiting Aptamer Structural Switching

    Directory of Open Access Journals (Sweden)

    Karol Alfaro

    2015-01-01

    Full Text Available A simple method to detect saxitoxin (STX, one of the main components of the paralytic shellfish poison from red tide, has been developed. By using a next generation dye for double-stranded DNA we were able to differentiate fluorescence from STX-binding aptamers when exposed to different concentrations of STX, suggesting a change in aptamer folding upon target binding. The developed method is extremely rapid, only requiring small sample volumes, with quantitative results in the concentration range of 15 ng/mL to 3 μg/mL of STX, with a detection limit of 7.5 ng/mL.

  7. Extraction and analysis of auxins in plants using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Lu, Qiaomei; Chen, Lihui; Lu, Minghua; Chen, Guonan; Zhang, Lan

    2010-03-10

    Auxin plays an important role in cell differentiation, apical dominance, and tropism in plants. A new method based on dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography-fluorescence detection (HPLC-FLD) has been established to detect auxin. A mixture of CHCl(3) (extraction solvent) and acetone (disperser solvent) was injected quickly into a sample solution with desired salt concentration and pH value, and then a cloudy solution consisting of many dispersed fine droplets of CHCl(3) was formed. After centrifugation, the sedimented phase was withdrawn and directly analyzed by HPLC-FLD. Under optimal conditions, four auxins were baseline separated within 3.5 min, with the minimal limit of detection of 0.02 ng mL(-1) and coefficient correlations in the range of 0.9980-0.9995. This simple method was successfully applied to real sample analysis. Experimental results showed that DLLME was a high-performance and powerful preconcentration method to extract and enrich related plant auxin.

  8. Electrochemical detection of ractopamine at arrays of micro-liquid | liquid interfaces.

    Science.gov (United States)

    Sairi, Masniza; Arrigan, Damien W M

    2015-01-01

    The behaviour of protonated ractopamine (RacH(+)) at an array of micro-interfaces between two immiscible electrolyte solutions (micro-ITIES) was investigated via cyclic voltammetry (CV) and linear sweep stripping voltammetry (LSSV). The micro-ITIES array was formed at silicon membranes containing 30 pores of radius 11.09±0.12 µm and pore centre-to-centre separation of 18.4±2.1 times the pore radius. CV shows that RacH(+) transferred across the water |1,6-dichlorohexane µITIES array at a very positive applied potential, close to the upper limit of the potential window. Nevertheless, CV was used in the estimation of some of the drug's thermodynamic parameters, such as the formal transfer potential and the Gibbs transfer energy. LSSV was implemented by pre-concentration of the drug, into the organic phase, followed by voltammetric detection, based on the back-transfer of RacH(+) from the organic to aqueous phase. Under optimised pre-concentration and detection conditions, a limit of detection of 0.1 µM was achieved. In addition, the impact of substances such as sugar, ascorbic acid, metal ions, amino acid and urea on RacH(+) detection was assessed. The detection of RacH(+) in artificial serum indicated that the presence of serum protein interferes in the detection signal, so that sample deproteinisation is required for feasible bioanalytical applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. A new interface weak-capacitance detection ASIC of capacitive liquid level sensor in the rocket

    Science.gov (United States)

    Yin, Liang; Qin, Yao; Liu, Xiao-Wei

    2017-11-01

    A new capacitive liquid level sensing interface weak-capacitance detection ASIC has been designed. This ASIC realized the detection of the output capacitance of the capacitive liquid level sensor, which converts the output capacitance of the capacitive liquid level sensor to voltage. The chip is fabricated in a standard 0.5μm CMOS process. The test results show that the linearity of capacitance detection of the ASIC is 0.05%, output noise is 3.7aF/Hz (when the capacitance which will be detected is 40 pF), the stability of capacitance detection is 7.4 × 10-5pF (1σ, 1h), the output zero position temperature coefficient is 4.5 uV/∘C. The test results prove that this interface ASIC can meet the requirement of high accuracy capacitance detection. Therefore, this interface ASIC can be applied in capacitive liquid level sensing and capacitive humidity sensing field.

  10. An ionic liquid-based nanofluid of titanium dioxide nanoparticles for effervescence-assisted dispersive liquid-liquid extraction for acaricide detection.

    Science.gov (United States)

    Wu, Xiaoling; Li, Xin; Yang, Miyi; Zeng, Haozhe; Zhang, Sanbing; Lu, Runhua; Gao, Haixiang; Xu, Donghui

    2017-05-12

    Phytophagous mites are usually considered a difficult problem for agricultural planting, and acaricides are applied to control diseases and pests. However, the overdose and misusage of acaricides causes pesticide residues. In this work, a simple and practical ionic liquid-based TiO 2 nanofluid, effervescence-assisted, dispersive liquid-liquid microextraction (EA-DLLME) method was developed to detect acaricides in honey and tea by high-performance liquid chromatography (HPLC-DAD). Oleophilic TiO 2 nanoparticles were synthesized by a facile solvothermal method to obtain greater stability of the nanofluid. The experimental parameters were optimized by a one-factor-at-a-time approach and included the effervescent tablet composition, ionic liquid selection, extractant composition, nanofluid volume, extraction temperature, extraction time and desorption conditions. Under the optimized conditions, the linear ranges of this proposed method were 0.5-500μgL -1 , with correlation coefficients in the range of 0.9985-1.0000. The extraction efficiencies for the target analytes varied from 70.70 to 84.58%. The detection and quantitation limits were in the ranges of 0.04-0.18μgL -1 and 0.13-0.60μgL -1 , respectively. The intra- and inter-day relative standard deviations (n=3) were found to range from 2.32 to 5.71%, which showed perfect repeatability. Overall, the EA-DLLME method was time-saving and environmentally friendly, with future potential for microextraction. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Generation of volatile copper species after in situ ionic liquid formation dispersive liquid-liquid microextraction prior to atomic absorption spectrometric detection.

    Science.gov (United States)

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka; Matusiewicz, Henryk

    2014-11-01

    The new procedure using in situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with generation of volatile species prior to electrothermal atomic absorption spectrometry (ET AAS) for the determination of copper in soil samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination. Under optimal conditions, the extraction in 10 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) (as the extraction solvent) was conducted. The ionic liquid served as two-task reagent: the efficient extractant and enhancement substance for generation step. The chemical generation of volatile species was performed by reduction of acidified copper solution (HCl 0.8 mol L(-1)) with NaBH4 (1.5%). Some essential parameters of the chemical generation such as NaBH4 and HCl concentrations, the kind and concentration of ionic liquid, carrier gas (Ar) flow rate, reaction and trapping time as well as pyrolysis and atomization temperatures were studied. For photogeneration the effect of the parameters such as the kind and concentration of low molecular weight organic acids and ionic liquid, carrier gas (Ar) flow rate, UV irradiation and ultrasonication time on the analytical signals were studied. The detection limit was found as 1.8 ng mL(-1) and the relative standard deviation (RSD) for seven replicate measurements of 100 µg mL(-1) in sample solution was 7%. The accuracy of the proposed method was evaluated by analysis of the certified reference materials. The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the soil and sediment samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Liquid chromatographic determination of uranium in seawater with coulometric detection

    International Nuclear Information System (INIS)

    Maekoya, Chiaki; Takata, Yoshinori

    1980-01-01

    A method of the separation with anion-exchange chromatography and of the coulometric detection of uranium in seawater was investigated. The size of the separation column used was 9 mm in inside diameter and 100 mm in length, and strong basic anion-exchange resin (Hitachi No. 2632) of carbonate form was packed in the column. A concentrator with two mini-columns in which the same resin was packed was applied for the preconcentration of uranium in seawater containing 20 g of potassium thiocyanate and 10 ml of hydrochloric acid per liter. Good result was obtained when a mixed solution of sodium carbonate (0.12 mol/l), sodium bicarbonate (0.08 mol/l), sodium bisulfite (0.03 mol/l) and sodium chloride (0.5 mol/l) was used as an eluent for the separation of uranium from vanadium. Sodium bisulfite was of use for dropping the background current based on an electrochemical reduction of dissolved oxygen. Sodium bicarbonate acted as an eliminator of an unknown peak by its bufferise effect. The optimum working electrode potential for the detection was -1.45 V vs. ferri-ferrocyanide. The detection limit was 3.2 x 10 -10 mol (80 ngU). The coefficient of variation at 3.0 ppb was about 4% (n=5) for seawater analysis. And the analysis time was approximately 1.5 hours. (author)

  13. Detection of radiation-induced hydrocarbons in baked sponge cake prepared with irradiated liquid egg

    International Nuclear Information System (INIS)

    Schulzki, G.; Spiegelberg, A.; Boegl, K.W.; Schreiber, G.A.

    1995-01-01

    For identification of irradiated food, radiation-induced volatile hydrocarbons (HC) are determined by gas chromatography in the non-polar fraction of fat. However, in complex food matrices the detection is often disturbed by fat-associated compounds. On-line coupling of high performance liquid chromatography (LC) and gas chromatography (GC) is very efficient to remove such compounds from the HC fraction. The high sensitivity of this fast and efficient technique is demonstrated by the example of detection of radiation-induced HC in fat isolated from baked sponge cake which had been prepared with irradiated liquid egg. (Author)

  14. Recognition of spectral amplitude codes by frequency swept coherent detection for flexible optial label switching

    DEFF Research Database (Denmark)

    Cao, Yongsheng; Osadchiy, Alexey Vladimirovich; Xin, Xiangjun

    2010-01-01

    We propose a new method of recognizing spectral amplitude code by using optical coherent detection with a frequency swept local light source oscillator. Our proposed method offer a substantial simplification in terms of required components to built optical label processing units with enhanced fle...... flexibility to accomodate for wavelength tuneability and a large numer of labels. We present a performance analysis, comparison with conventional spectral codes recognition methods, based on computer simulation results. We consider a payload bit rate of 40 Gb/s....

  15. Liquid chromatographic determination of zearalenone and zearalenol in animal feeds and grains, using fluorescence detection.

    Science.gov (United States)

    Bagneris, R W; Gaul, J A; Ware, G M

    1986-01-01

    A liquid chromatographic (LC) method was developed for the determination of zearalenone and zearalenol in grains and mixed animal feeds. Samples are extracted with chloroform and purified by a base-acid liquid-liquid partition. Zearalenone and zearalenol are separated by reverse phase LC and determined by fluorescence detection, excitation wavelength 236 nm with a 418 nm cutoff filter. The method was applied to the determination of zearalenone and zearalenol in 395 survey samples of corn, oats, barley, sorghum, silage, and finished feeds. The limit of detection is 10 ng/g for both toxins. The range of naturally occurring toxins found was 10-4,000 ng/g. Average recoveries were 84% for zearlenone and 69% for zearalenol. Coefficients of variation were 24.6% for zearalenone and 30.8% for zearalenol for crop year 1980, and 28.3% for zearalenone and 22.0% for zearalenol for crop year 1981.

  16. Distant optical detection of small rotations and displacements by means of chiral liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shibaev, Petr V., E-mail: shibpv@yahoo.com, E-mail: shibayev@fordham.edu; Troisi, Juliana; Reddy, Kathryn [Department of Physics and Engineering Physics, Fordham University, 441 East Fordham Road, Bronx, New York, 10458 (United States); Iljin, Andrey [Institute of Physics, National Academy of Sciences of Ukraine, Prospect Nauki 46, Kiev, 03028 (Ukraine)

    2014-01-15

    The paper describes novel chiral viscoelastic liquid crystalline mixtures and their application for the detection of small rotational displacements of two plates confining cholesteric liquid crystals (CLC). The mixtures are characterized by extremely high viscosities and stability of the selective reflection band (SRB) at ambient temperatures. Even a small rotation applied to the chiral liquid crystal (CLC) cell results in dramatic changes of the reflective properties of sandwiched CLC films. The angle and direction of rotation as well as the magnitude of CLC's shear deformation can be determined for a variety of experimental geometries, each of which is characterized by its own response function. The proposed model explains changes in the reflection spectra for different experimental geometries and relates them to the angle of rotation and magnitude of shear. The method was tested for a detection of small rotations from a distance of up to 50 m and allows for resolving small rotations of the order of fractions of degrees.

  17. Circulating tumor DNA detection (liquid biopsy: prospects in oncology

    Directory of Open Access Journals (Sweden)

    N. V. Zhukov

    2015-01-01

    Full Text Available Modern research techniques allows tumor studying in almost any level: protein expression, structural changes of DNA, RNA, epigenetic changes, activity of signaling pathways, microenvironment, interaction with the immune system, etc. However, tumor samples are obtained as 100 years ago – by tumor biopsy prior to treatment. Based on available data about intratumoral heterogeneity and tumor changes during treatment, it may be one of the factors braking to obtain required information of tumor biology. According to study, the analysis of circulating tumor DNA (ctDNA allows to hope to overcome the key limitations of routine biopsy. One of the key benefits of ctDNA analysis is the ability to a more comprehensive tumor investigation, while maintaining a high level of specificity, almost as well as a routine biopsy. Detection sensitivity of ctDNA continues to increase due to the development of new technology. The study of ctDNA may lead to breakthrough results in understanding of tumors molecular heterogeneity, development of resistance to anticancer therapy and ways to overcome it, screening and a number of other key areas of modern oncology.

  18. Determination of Peroxide-Based Explosives Using Liquid Chromatography with On-Line Infrared Detection

    NARCIS (Netherlands)

    Schulte-Ladbeck, Rasmus; Edelmann, Andrea; Quintas, Guillermo; Lendl, Bernhard; Karst, U.

    2006-01-01

    A nondestructive analytical method for peroxide-based explosives determination in solid samples is described. Reversed-phase high-performance liquid chromatography in combination with on-line Fourier transform infrared (FT-IR) detection is used for the analysis of triacetonetriperoxide (TATP) and

  19. Simultaneous and consecutive two-photon excited fluorescence detection in conventional-size liquid chromatography.

    NARCIS (Netherlands)

    Gooijer, C.; Brinkman, U.A.T.; Velthorst, N.H.; van de Nesse, R.J.; van der Wegen, R.J.

    1995-01-01

    The applicability of two-photon excitation (TPE) for fluorescence detection in flow dynamic systems was explored. Emphasis was on conventional-size liquid chromatography (LC) and a direct comparison was made with one-photon excitation (OPE) by the use of standard laser- and lamp excitation.

  20. A Coincidence Detection Mechanism Controls PX-BAR Domain-Mediated Endocytic Membrane Remodeling via an Allosteric Structural Switch.

    Science.gov (United States)

    Lo, Wen-Ting; Vujičić Žagar, Andreja; Gerth, Fabian; Lehmann, Martin; Puchkov, Dymtro; Krylova, Oxana; Freund, Christian; Scapozza, Leonardo; Vadas, Oscar; Haucke, Volker

    2017-11-20

    Clathrin-mediated endocytosis occurs by bending and remodeling of the membrane underneath the coat. Bin-amphiphysin-rvs (BAR) domain proteins are crucial for endocytic membrane remodeling, but how their activity is spatiotemporally controlled is largely unknown. We demonstrate that the membrane remodeling activity of sorting nexin 9 (SNX9), a late-acting endocytic PX-BAR domain protein required for constriction of U-shaped endocytic intermediates, is controlled by an allosteric structural switch involving coincident detection of the clathrin adaptor AP2 and phosphatidylinositol-3,4-bisphosphate (PI(3,4)P 2 ) at endocytic sites. Structural, biochemical, and cell biological data show that SNX9 is autoinhibited in solution. Binding to PI(3,4)P 2 via its PX-BAR domain, and concomitant association with AP2 via sequences in the linker region, releases SNX9 autoinhibitory contacts to enable membrane constriction. Our results reveal a mechanism for restricting the latent membrane remodeling activity of BAR domain proteins to allow spatiotemporal coupling of membrane constriction to the progression of the endocytic pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Magnetic switching of optical reflectivity in nanomagnet/micromirror suspensions: colloid displays as a potential alternative to liquid crystal displays.

    Science.gov (United States)

    Bubenhofer, S B; Athanassiou, E K; Grass, R N; Koehler, F M; Rossier, M; Stark, W J

    2009-12-02

    Two-particle colloids containing nanomagnets and microscale mirrors can be prepared from iron oxide nanoparticles, microscale metal flakes and high-density liquids stabilizing the mirror suspension against sedimentation by matching the constituent's density. The free Brownian rotation of the micromirrors can be magnetically controlled through an anisotropic change in impulse transport arising from impacts of the magnetic nanoparticles onto the anisotropic flakes. The resulting rapid mirror orientation allows large changes in light transmission and switchable optical reflectivity. The preparation of a passive display was conceptually demonstrated through colloid confinement in a planar cavity over an array of individually addressable solenoids and resulted in 4 x 4 digit displays with a reaction time of less than 100 ms.

  2. Focal length measurement of a varifocal liquid lens with capacitance detection

    Science.gov (United States)

    Noda, Kentaro; Binh-Khiem, Nguyen; Takei, Yusuke; Takahata, Tomoyuki; Matsumoto, Kiyoshi; Shimoyama, Isao

    2014-04-01

    This paper reports on a detailed deformation model of varifocal liquid lenses fabricated by Parylene-on-liquid-deposition (POLD), which can be applied to measure and adjust the focal length of such lenses without using extra sensors or sensing mechanisms. The lens was fabricated by encapsulating a liquid between a transparent electrode and a polymer film that was covered with a metal electrode. When voltage is applied to the two electrodes, the lens deforms due to the electrostatic force, and its focal length and the capacitance between the two electrodes change simultaneously. This characteristic enables the focal length of the lens to be adjusted and detected by measuring the capacitance change. The focal length of the fabricated varifocal liquid lens changed from 153.6 to 82.6 mm by applying 150-V. The focal length change of the liquid lens was calculated from the change in its capacitance. Finally, to confirm the efficiency of this varifocal liquid lens, we fabricated a confocal distance sensor using the lens for laser scanning and demonstrated that this system can be used to measure distances of 94-140 mm with an average error of 0.83 mm and a standard deviation of 0.77 mm.

  3. Detection of Adulterants and Contaminants in Liquid Foods-A Review.

    Science.gov (United States)

    Jha, Shyam Narayan; Jaiswal, Pranita; Grewal, Manpreet Kaur; Gupta, Mansha; Bhardwaj, Rishi

    2016-07-26

    Milk and fruit juices have paramount importance in human diet. Increasing demand of these liquid foods has made them vulnerable to economic adulteration during processing and in supply chain. Adulterants are difficult to detect by consumers and thus necessitating the requirement of rapid, accurate and sensitive detection. The potential adulterants in milk and fruit juices and their limits set by different regulatory bodies have been briefly described in this review. Potential advantages and limitations of various techniques such as physicochemical methods, chromatography, immunoassays, molecular, electrical, spectroscopy with chemometrics, electronic nose, and biosensors have been described. Spectroscopy in combination with chemometrics has shown potential for rapid, precise, and sensitive detection of potential adulterants in these liquid foods.

  4. Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Sorensen, P; Dahl, C E

    2011-02-14

    We show for the first time that the quenching of electronic excitation from nuclear recoils in liquid xenon is well-described by Lindhard theory, if the nuclear recoil energy is reconstructed using the combined (scintillation and ionization) energy scale proposed by Shutt et al.. We argue for the adoption of this perspective in favor of the existing preference for reconstructing nuclear recoil energy solely from primary scintillation. We show that signal partitioning into scintillation and ionization is well-described by the Thomas-Imel box model. We discuss the implications for liquid xenon detectors aimed at the direct detection of dark matter.

  5. Breast cancer detection using magnetic resonance imaging in breasts injected with liquid silicone.

    Science.gov (United States)

    Peng, H L; Wu, C C; Choi, W M; Hui, M S; Lu, T N; Chen, L K

    1999-12-01

    Two patients who had received silicone injections in their breasts several years ago presented with breast complaints. Excluding cancer in these patients was very difficult. Mammograms were very difficult to interpret, as were the physical findings. Carcinoma was successfully detected by magnetic resonance imaging. When women who underwent the injudicious injection of silicone reach the cancer-prone age, the examining physicians should have a greater awareness of the detection and management of carcinoma coexistent with silicone mastopathy. We think that MRI is potentially valuable in the evaluation of the breast lesions; it plays an important role in the detection of breast cancer in breasts augmented with liquid silicone.

  6. Detection of peptides by precolumn derivatization with biuret reagent and preconcentration on capillary liquid chromatography columns with electrochemical detection.

    Science.gov (United States)

    Shen, H; Witowski, S R; Boyd, B W; Kennedy, R T

    1999-03-01

    The separation and detection of biuret complexes of neuropeptides by capillary liquid chromatography with electrochemical detection was explored. Capillaries of 25-micron inner diameter packed with base-resistant, polymer-based reversed-phase particles were used for separation, and C-fiber electrodes were used for detection. Detection at the C-fiber electrode was found to have some differences in relative sensitivity for peptides compared to glassy carbon electrodes used previously. On-column preconcentration of preformed complexes allowed up to 1-microL samples to be injected with minimal band broadening resulting in a 100-fold improvement in concentration detection limit with no effect on mass detection limit. Concentration detection limits ranged from 5 to 59 pM, depending upon the peptide, corresponding to 5-59 amol injected. The low concentration detection limit was possible because of minimal baseline disturbances, minimal formation of unwanted products, and high efficiency of complex formation associated with biuret derivatization. The method was applied to determination of vasopressin and bradykinin in dialysates collected with 5-min sampling frequency from the rat supraoptic nucleus.

  7. Determination of lansoprazole enantiomers in dog plasma by column-switching liquid chromatography with tandem mass spectrometry and its application to a preclinical pharmacokinetic study.

    Science.gov (United States)

    Wang, Hao; Sun, Yantong; Meng, Xiangjun; Yang, Bo; Wang, Jian; Yang, Yan; Gu, Jingkai

    2015-09-01

    Lansoprazole, a selective proton pump inhibitor, has a chiral benzimidazole sulfoxide structure and is used for the treatment of gastric acid hypersecretory related diseases. To investigate its stereoselective pharmacokinetics, a column-switching liquid chromatography with tandem mass spectrometry method was developed for the determination of lansoprazole enantiomers in dog plasma using (+)-pantoprazole as an internal standard. After a simple protein precipitation procedure with acetonitrile, matrix components left behind after sample preparation were further eliminated from the sample by reversed-phase chromatography on a C18 column. The fluent was fed to a chiral column for the separation of lansoprazole enantiomers. Baseline separation of lansoprazole enantiomers was achieved on a Chiralcel OZ-RH column using acetonitrile/0.1% formic acid in water (35:65, v/v) as the mobile phase at 40°C. The linearity of the calibration curves ranged from 3 to 800 ng/mL for each enantiomer. Intra- and inter-day precisions ranged from 2.1 to 7.3% with an accuracy of ±1.7% for (+)-lansoprazole, and from 1.6 to 6.9% with an accuracy of ±3.5% for (-)-lansoprazole, respectively. The validated method was successfully applied for the stereoselective pharmacokinetic study of lansoprazole in beagle dog after intravenous infusion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Ultra-high performance liquid chromatography with fluorescence detection following salting-out assisted liquid-liquid extraction for the analysis of benzimidazole residues in farm fish samples.

    Science.gov (United States)

    Tejada-Casado, Carmen; Lara, Francisco J; García-Campaña, Ana M; Del Olmo-Iruela, Monsalud

    2018-03-30

    Ultra-high performance liquid chromatography (UHPLC) coupled with fluorescence detection (FL) has been proposed for the first time to determine thirteen benzimidazoles (BZs) in farmed fish samples. In order to optimize the chromatographic separation, parameters such as mobile phase composition and flow rate were carefully studied, establishing a gradient mode with a mobile phase consisted of water (solvent A) and acetonitrile (solvent B) at a flow rate of 0.4 mL/min. The separation was performed on a Zorbax Eclipse Plus RRHD C 18 column (50 × 2.1 mm, 1.8 μm), involving a total analysis time lower than 12 min. Salting-out assisted liquid-liquid extraction (SALLE) was applied as sample treatment to different types of farmed fish (trout, sea bream and sea bass). To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized including the amount of sample, type and volume of the extraction solvent, and the nature and amount of the salt used. Characterization of the method in terms of performance characteristics was carried out, obtaining satisfactory results for the linearity (R 2  ≥ 0.997), repeatability (RSD ≤ 6.1%), reproducibility (RSD ≤ 10.8%) and recoveries (R ≥ 79%; RSD ≤ 7.8%). Detection limits between 0.04-29.9 μg kg -1 were obtained, demonstrating the applicability of this fast, simple and environmentally friendly method. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Efficient in-band diode-pumped Q-switched solid state laser for methane detection, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop an efficient, tunable Q-switched SSL operating at a wavelength of 1651 nm with pulse energy >1 mJ at 2000 Hz repetition rate with in-band...

  10. Performance evaluation of evaporative light scattering detection and charged aerosol detection in reversed phase liquid chromatography.

    Science.gov (United States)

    Vervoort, N; Daemen, D; Török, G

    2008-05-02

    In pharmaceutical industry ultraviolet (UV) detection is often used as the preferred detection technique in HPLC analysis since most pharmaceutical compounds possess a UV-absorbing chromophore. However, in case the active pharmaceutical ingredient (API) does not have a UV-absorbing chromophore, or if some of the impurities present lack a chromophore, they will not be detected in routine HPLC analysis employing only a UV detector and alternative detection schemes have to be used. Refractive index detection or mass spectroscopy (MS) can be used but these detectors have their intrinsic weaknesses, such as lack of sensitivity or high cost. With the appearance of semi-universal techniques such as evaporative light scattering detection (ELSD), and more recent, charged aerosol detection (CAD), detection of non-UV-absorbing compounds became feasible without having to resort to such complex or costly detection methods. This paper evaluates the different performance characteristics such as sensitivity, linearity, accuracy and precision of both the ELSD and CAD detector coupled to HPLC. One disadvantage of this type of detector is the non-linear response behaviour which makes direct linear regression for making calibration curves inaccurate.

  11. Ion-pair reversed phase liquid chromatography with ultraviolet detection for analysis of ultraviolet transparent cations.

    Science.gov (United States)

    He, Yan; Cook, Kenneth S; Littlepage, Eric; Cundy, John; Mangalathillam, Ratish; Jones, Michael T

    2015-08-21

    This paper describes the use of an anionic ion-pair reagent (IPR) to impove the ultraviolet (UV) detection and hydrophobic retention of polar and UV transparent cations. Anionic IPR added to the mobile phase forms an ion-pair with cations. Formation of the ion-pair causes a redshift in the absorption wavength, making it possible for direct UV detection of UV-inactive cations. The ion-pairs with increased hydrophobicity were separated by reversed phase liquid chromatography (RPLC). Different perfluorinated caboxylic acids (trifluoroacetic acid, heptafluorobutyric acid, nonafluoropentanoic acid) were evaluted as IPR in the separation and detection of the common cations sodium, ammonium and Tris(hydroxymethyl)aminomethane (Tris). The effects of the IPR type and concentration on separation and detection have been investigated to understand the separation and detection mechanisms. The optimal separation and detection condtions were attained with mobile phase containing 0.1% nonafluoropentanoic acid and with the UV detection at 210nm. UV detection and charged aerosol detection (CAD) were compared in the quantitation of the cations. The limit of quantitation (LOQ) of sodium and Tris with UV detection is comparable to that by CAD. The LOQ of ammonium with UV detection (1ppm or 3ng) is about 20-fold lower than that (20ppm or 60ng) by CAD. The RPLC-UV method was used to monitor ammonium clearance during ultrafiltration and diafiltration in the manfucaturing of biopharmceutical drug substance. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Determination of organophosphorus pesticides by dispersive liquid-liquid micro extraction coupled with gas chromatography-electron capture detection

    International Nuclear Information System (INIS)

    Mohd Marsin Sanagi; Siti Umairah Mokhtar; Mazidatul Akmam Miskam; Wan Aini Wan Ibrahim

    2011-01-01

    A simple, rapid and sensitive method termed as dispersive liquid-liquid micro extraction (DLLME) combined with gas chromatography-electron capture detector (GC-ECD) was developed for the determination of selected organophosphorus pesticides (OPPs) namely chloropyrifos, dimethoate and diazinon in water sample. In this method, a mixture of carbon disulfide, CS 2 (extraction solvent) and methanol (disperser solvent) was rapidly injected using syringe into the 5.00 mL water sample to form a cloudy solution where the OPPs were extracted into the fine droplets of extraction solvent. Upon centrifugation for 3 min at 3500 rpm, the fine droplets were sedimented at the bottom of the centrifuge tube. Sedimented phase (1 μL) was injected into the GC-ECD for separation and determination of OPPs. Important extraction parameters, such as type of disperser solvent, volume of extraction solvent and volume of disperser solvent were investigated. The optimized conditions for DLLME of the selected OPPs were methanol as disperser solvent, 30 μL of extraction solvent (CS 2 ) and 1.0 mL of disperser solvent (methanol). Under the optimum extraction conditions, the method showed good linearity in the range of 0.1 to 1.0 μg/ mL with correlation coefficient (r 2 ), in the range of 0.9976 to 0.9994 and low limits of detection (LOD) between 0.047 and 0.201 μg/ mL. The proposed method provided acceptable recoveries (72.67- 144 %) with good RSDs ranging from 2.74 % to 7.48 %. This method was successfully applied to the determination of OPPs in water samples obtained from a golf course and chloropyrifos and diazinon were detected at concentration 0.18 μg/ mL and 0.07 μg/ mL, respectively. (author)

  13. Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

    Science.gov (United States)

    Woodruff, Steven D.; Mcintyre, Dustin L.

    2016-03-29

    A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

  14. Viscosity-density sensor with resonant torsional paddle for direct detection in liquid.

    Science.gov (United States)

    Li, H; Wang, J; Li, X; Chen, D

    2011-12-01

    A novel micro-machined biosensor based on the resonant torsional paddle with electromagnetic excitation which can work in liquid directly is presented. The sensor designed consists of two paddles with resonant torsional mode, in which the energy loss of the resonator during the vibration is so lower that it can be suitable for detection in liquid. Finite element method analysis was carried out to guarantee the sensitivity of the sensor. Micro electro-mechanical system (MEMS) bulk silicon processes were adopted to accomplish the fabrication. A positive-feedback circuit with energy compensation is designed to improve the characteristics of the sensor in liquid. Experiments show that the resonant torsional paddle can work directly in liquid and the Q-factor of the sensor in liquid can be improved from 2.65 to 40 with energy compensation. Viscosity tests and density tests for the sensor show that the decrease in frequency and the decrease in Q-factor are related to density and viscosity of the solutions, respectively.

  15. CARS detection of liquid-like phase appearance in small mesopores

    Science.gov (United States)

    Arakcheev, Vladimir G.; Bekin, Alexey N.; Morozov, Viacheslav B.

    2017-11-01

    Nonlinear-optical spectroscopic techniques that employ signals from the molecules located inside nanopores have promising potential for investigations of fluid behavior under nanoconfinement. Here, we apply coherent anti-Stokes spectroscopy to investigate the appearance of a liquid-like phase of carbon dioxide in mesoporous Vycor glass under isothermal compression. The spectra of the Q-branch (1388 cm‑1) are registered at  ‑11 °C in a wide pressure range, starting from submonolayer coverage of the pore wall up to the bulk saturation pressure. Results show that a spectral contribution, similar to that of the bulk liquid, appears at relatively low pressure that is several times lower than the capillary-condensation pressure. The Raman shift of the peak is equal to that of the bulk liquid, although the linewidth is somewhat increased. The peak is attributed to the layers adsorbed beyond the monolayer or to small liquid-like clusters appearing in specific areas of the porous network. The spectroscopic approach presented here demonstrates the ability to detect and estimate small amounts of the liquid-like phase and to distinguish it from the layers strongly interacting with the pore surface.

  16. Lignin-AuNPs liquid marble for remotely-controllable detection of Pb2+

    Science.gov (United States)

    Han, Guocheng; Wang, Xiaoying; Hamel, Jonathan; Zhu, Hongli; Sun, Runcang

    2016-12-01

    This work reported the green and facile fabrication of a versatile lignin-AuNP composite, which was readily and remotely encapsulated to form novel liquid marbles. The marbles can stay suspended in water, and show excellent photothermal conversion properties, as well as visual detection and adsorption towards Pb2+. More importantly, the marbles can simultaneously remotely detect and adsorb Pb2+ via co-precipitation by simply controlling the near infrared (NIR) irradiation. It is believed that the remotely-controllable NIR-responsive lignin-AuNPs liquid marble can be used in Pb2+-related reactions. The liquid marble can be placed in the system at the very beginning of the reaction and stably stays on the surface until the reaction has ended. After reacting, upon remote NIR irradiation, the liquid marble bursts to adsorb Pb2+, and the residual Pb2+ can be collected. This facile manipulation strategy does not use complicated nanostructures or sophisticated equipment, so it has potential applications for channel-free microfluidics, smart microreactors, microengines, and so on.

  17. Ionic liquid-based dispersive liquid-liquid microextraction combined with high performance liquid chromatography-UV detection for simultaneous preconcentration and determination of Ni, Co, Cu and Zn in water samples

    Directory of Open Access Journals (Sweden)

    Asghari Alireza

    2014-01-01

    Full Text Available Ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME coupled with high performance liquid chromatography (HPLC-UV detection was developed for simultaneous extraction and determination of nickel, cobalt, copper and zinc ions. In the proposed approach, salophen (N,N'-bis(salisyliden-1,2-phenylenediamine was used as a chelating agent; the ionic liquid, 1-hexeyl-3-methylimidazolium hexafluorophosphate, and acetone were selected as extracting and dispersive solvents, respectively. After extraction, phase separation was performed by centrifugation and the sedimented phase (ionic liquid was solubilized in acetonitrile and directly injected into the HPLC for subsequent analysis. Baseline separation of metal ion complexes was achieved on a RP-C18 column using a gradient elution of the mixtures of methanol-acetonitrile-water as the mobile phase at a flow rate of 1.0 mL min-1. The influence of variables such as sample pH, concentration of the chelating agent, amount of ionic liquid (extraction solvent, disperser solvent volume, extraction time, salt effect and centrifugation speed were studied and optimized. Under the optimum conditions, the enrichment factor of 222 was obtained. The detection limits for Ni, Co, Cu and Zn were 0.8, 1.6, 1.9 and 2.8 μg L−1, respectively. The relative standard deviations (RSDs were in the range of 3.6-5.0 % for all of the investigated metal ions. The proposed procedure was successfully applied to the determination of the studied metal ions in water samples.

  18. Definition and means of maintaining the process vacuum liquid detection interlock systems portion of the PFP safety envelope

    International Nuclear Information System (INIS)

    THOMAS, R.J.

    1999-01-01

    The Process Vacuum Liquid Detection interlock systems prevent intrusion of process liquids into the HEPA filters downstream of demisters No.6 and No.7 during Process Vacuum System operation. This prevents liquid intrusion into the filters, which could cause a criticality. The Safety Envelope (SE) includes the equipment, which detects the presence of liquids in the vacuum headers; isolates the filters; shuts down the vacuum pumps; and alarms the condition. This report identifies the equipment in the SE operating, maintenance, and surveillance procedures needed to maintain the SE equipment; and rationale for exclusion of some equipment and testing from the SE

  19. Liquid chromatography-fluorescence and liquid chromatography-mass spectrometry detection of tryptophan degradation products of a recombinant monoclonal antibody.

    Science.gov (United States)

    Nowak, Christine; Ponniah, Gomathinayagam; Cheng, Guilong; Kita, Adriana; Neill, Alyssa; Kori, Yekaterina; Liu, Hongcheng

    2016-03-01

    Light exposure is one of several conditions used to study the degradation pathways of recombinant monoclonal antibodies. Tryptophan is of particular interest among the 20 amino acids because it is the most photosensitive. Tryptophan degradation forms several products, including an even stronger photosensitizer and several reactive oxygen species. The current study reports a specific peptide mapping procedure to monitor tryptophan degradation. Instead of monitoring peptides using UV 214 nm, fluorescence detection with an excitation wavelength of 295 nm and an emission wavelength of 350 nm was used to enable specific detection of tryptophan-containing peptides. Peaks that decreased in area over time are likely to contain susceptible tryptophan residues. This observation can allow further liquid chromatography-mass spectrometry (LC-MS) analysis to focus only on those peaks to confirm tryptophan degradation products. After confirmation of tryptophan degradation, susceptibility of tryptophan residues can be compared based on the peak area decrease. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Method development for the quantitation of ABT-578 in rabbit artery tissue by 96-well liquid-liquid extraction and liquid chromatography/tandem mass spectrometric detection.

    Science.gov (United States)

    Ji, Qin C; Zhang, Jun; Rodila, Ramona; Watson, Pamela; El-Shourbagy, Tawakol

    2004-01-01

    Quantitative determination of drug concentrations in tissue samples can provide critical information for drug metabolism, kinetics, and toxicity evaluations. For analysis of tissue samples using liquid chromatography/tandem mass spectrometric (LC/MS/MS) detection, homogenization is a critical step in achieving good assay performance. Assay performance can be closely evaluated by spiking the drug directly into tissue samples prior to homogenization. It is especially important to include this assay evaluation for the analysis of artery tissue samples because artery tissue is very elastic, making it quite a challenge to develop an effective procedure for homogenization. An LC/MS/MS assay in 96-well format using liquid-liquid extraction was developed for analyzing ABT-578 in rabbit artery samples. Tissue quality control samples were prepared by spiking ABT-578 stock solutions directly into the tissue before homogenization. The usage of the tissue control samples gives a thorough evaluation of the sample preparation process that includes both homogenization and sample extraction. A 20% blood in saline solution was used as a homogenization solution. Calibration standards were made by spiking ABT-578 into rabbit whole blood. Blood quality control samples were also prepared by spiking ABT-578 into rabbit whole blood. These blood QC samples were used to confirm the validity of the calibration curve. A lower limit of quantitation of 0.050 ng/mL was achieved. The linear dynamic range of blood standards was from 0.050-30.3 ng/mL with the correlation coefficient (r) ranging from 0.9969-0.9996. Overall %CV was between 1.3 and 7.0%, and analytical recovery was between 98.2 and 105.8% for blood QC samples. The %CVs for tissue QC samples were between 6.7 and 13.0%, and analytical recovery after correction was between 93.5 and 114.3%. Copyright 2004 John Wiley & Sons, Ltd.

  1. Research on the detection system of liquid concentration base on birefringence light transmission method

    Science.gov (United States)

    Li, Tianze; Zhang, Xia; Hou, Luan; Jiang, Chuan

    2010-10-01

    The characteristics of the beam transmitting in the optical fiber and the liquid medium are analyzed in this paper. On this basis, a new type of semiconductor optical position sensitive detector is used for a receiving device, a light transmission method of birefringence is presented,and a set of opto-electrical detection system which is applied to detect liquid concentration is designed. The system is mainly composed of semiconductor lasers,optical systems, Psd signal conditioning circuit, Single-chip System, A/D conversion circuit and display circuit. Through theoretical analysis and experimental simulations, the accuracy of this system has been verified. Some main factors affecting the test results are analyzed detailedly in this paper. The experiments show that the temperature drift and the light intensity have a very small impact on this system. The system has some advantages, such as the simple structure, high sensitivity, good stability, fast response time, high degree of automation, and so on. It also can achieve the real-time detection of liquid concentration conveniently and accurately. The system can be widely applied in chemical, food, pharmacy and many other industries. It has broad prospects of application.

  2. Real Time, Non-intrusive Detection of Liquid Nitrogen in Liquid Oxygen (LOX) at High Pressure and High Flow Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Technical Abstract The Stennis Space Center (SSC) needs the sensors that are capable and can be operated in liquid oxygen (LOX) and or liquid hydrogen (LH2)...

  3. Nanomechanical coupling enables detection and imaging of 5 nm superparamagnetic particles in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, Christian; Herruzo, Elena T; Lozano, Jose R; Garcia, Ricardo, E-mail: ricardo.garcia@imm.cnm.csic.es [Instituto de Microelectronica de Madrid, CSIC, Isaac Newton 8, E-28760 Tres Cantos, Madrid (Spain)

    2011-03-25

    We demonstrate that a force microscope operated in a bimodal mode enables the imaging and detection of superparamagnetic particles down to 5 nm. The bimodal method exploits the nanomechanical coupling of the excited modes to enhance the sensitivity of the higher mode to detect changes in material properties. The coupling requires the presence of nonlinear forces. Remarkably, bimodal operation enables us to identify changes of slowly varying forces (quasi-linear) in the presence of a stronger nonlinear force. Thus, unambiguous identification of single apoferritin (non-magnetic) and ferritin (magnetic) molecules in air and liquid is accomplished.

  4. A suspending-droplet mode paper-based microfluidic platform for low-cost, rapid, and convenient detection of lead(II) ions in liquid solution.

    Science.gov (United States)

    Sun, Han; Li, Wanbo; Dong, Zhen-Zhen; Hu, Chong; Leung, Chung-Hang; Ma, Dik-Lung; Ren, Kangning

    2018-01-15

    A paper-based microfluidic device based on unconventional principle was developed and used to detect lead ions through a two-step process including heated incubation and subsequent mixing. The device was made by generating a superhydrophobic pattern, which defines channel and reservoir barriers, on a water-impermeable paper substrate, followed by loading and drying the reagents in the defined reservoirs. Different from the conventional paper-based devices that are made of water-permeable paper, the as-prepared device holds water drops in discrete reservoirs, and the water drops will not move unless the device is titled along the direction of the predefined channels. In this way, the liquid samples applied onto the device are handled as individual drops and could be stored, transported, and mixed on demand. Different from the conventional paper-based devices that use capillary force to drive liquid, our new device uses wetting and gravity as driving force. We name this operation principle suspending-droplet mode paper-based device (SD-μPAD). The use of a Teflon contact-printing stamp makes the production of such devices rapid, cost efficient, and mass productive. Utilizing a G-quadruplex-based luminescence switch-on assay, we demonstrated rapid, convenient, highly sensitive, and low cost detection of lead(II) ions in water samples, using a custom made battery-powered portable device, and a smart phone as the detector. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Ionic liquid-based zinc oxide nanofluid for vortex assisted liquid liquid microextraction of inorganic mercury in environmental waters prior to cold vapor atomic fluorescence spectroscopic detection.

    Science.gov (United States)

    Amde, Meseret; Liu, Jing-Fu; Tan, Zhi-Qiang; Bekana, Deribachew

    2016-01-01

    Zinc oxide nanofluid (ZnO-NF) based vortex assisted liquid liquid microextraction (ZnO-NF VA-LLME) was developed and employed in extraction of inorganic mercury (Hg(2+)) in environmental water samples, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). Unlike other dispersive liquid liquid microextraction techniques, ZnO-NF VA-LLME is free of volatile organic solvents and dispersive solvent consumption. Analytical signals were obtained without back-extraction from the ZnO-NF phase prior to CV-AFS determination. Some essential parameters of the ZnO-NF VA-LLME and cold vapor generation such as composition and volume of the nanofluid, vortexing time, pH of the sample solution, amount of the chelating agent, ionic strength and matrix interferences have been studied. Under optimal conditions, efficient extraction of 1ng/mL of Hg(2+) in 10mL of sample solution was achieved using 50μL of ZnO-NF. The enrichment factor before dilution, detection limits and limits of quantification of the method were about 190, 0.019 and 0.064ng/mL, respectively. The intra and inter days relative standard deviations (n=8) were found to be 4.6% and 7.8%, respectively, at 1ng/mL spiking level. The accuracy of the current method was also evaluated by the analysis of certified reference materials, and the measured Hg(2+) concentration of GBW08603 (9.6ng/mL) and GBW(E)080392 (8.9ng/mL) agreed well with their certified value (10ng/mL). The method was applied to the analysis of Hg(2+) in effluent, influent, lake and river water samples, with recoveries in the range of 79.8-92.8% and 83.6-106.1% at 1ng/mL and 5ng/mL spiking levels, respectively. Overall, ZnO-NF VA-LLME is fast, simple, cost-effective and environmentally friendly and it can be employed for efficient enrichment of the analyte from various water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Heat-transfer resistance at solid-liquid interfaces: a tool for the detection of single-nucleotide polymorphisms in DNA.

    Science.gov (United States)

    van Grinsven, Bart; Vanden Bon, Natalie; Strauven, Hannelore; Grieten, Lars; Murib, Mohammed; Monroy, Kathia L Jiménez; Janssens, Stoffel D; Haenen, Ken; Schöning, Michael J; Vermeeren, Veronique; Ameloot, Marcel; Michiels, Luc; Thoelen, Ronald; De Ceuninck, Ward; Wagner, Patrick

    2012-03-27

    In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA. © 2012 American Chemical Society

  7. Fundamental studies on the switching in liquid nitrogen environment using vacuum switches for application in future high-temperature superconducting medium-voltage power grids; Grundsatzuntersuchungen zum Schalten in Fluessigstickstoff-Umgebung mit Vakuumschaltern zur Anwendung in zukuenftigen Hochtemperatur-Supraleitungs-Mittelspannungsnetzen

    Energy Technology Data Exchange (ETDEWEB)

    Golde, Karsten

    2016-06-24

    By means of superconducting equipment it is possible to reduce the transmission losses in distribution networks while increasing the transmission capacity. As a result even saving a superimposed voltage level would be possible, which can put higher investment costs compared to conventional equipment into perspective. For operation of superconducting systems it is necessary to integrate all equipment in the cooling circuit. This also includes switchgears. Due to cooling with liquid nitrogen, however, only vacuum switching technology comes into question. Thus, the suitability of vacuum switches is investigated in this work. For this purpose the mechanics of the interrupters is considered first. Material investigations and switching experiments at ambient temperature and in liquid nitrogen supply information on potential issues. For this purpose, a special pneumatic construction is designed, which allows tens of thousands of switching cycles. Furthermore, the electrical resistance of the interrupters is considered. Since the contact system consists almost exclusively of copper, a remaining residual resistance and appropriate thermal losses must be considered. Since they have to be cooled back, an appropriate evaluation is given taking environmental parameters into account. The dielectric strength of vacuum interrupters is considered both at ambient temperature as well as directly in liquid nitrogen. For this purpose different contact distances are set at different interrupter types. A distinction is made between internal and external dielectric strength. Conditioning and deconditioning effects are minimized by an appropriate choice of the test circuit. The current chopping and resulting overvoltages are considered to be one of the few drawbacks of vacuum switching technology. Using a practical test circuit the height of chopping current is determined and compared for different temperatures. Due to strong scattering the evaluation is done using statistical methods. At

  8. Separation and detection of plasmalogen in marine invertebrates by high-performance liquid chromatography with evaporative light-scattering detection.

    Science.gov (United States)

    Yamashita, Shinji; Abe, Akihiro; Nakagawa, Kiyotaka; Kinoshita, Mikio; Miyazawa, Teruo

    2014-12-01

    We have developed a new method for determining ethanolamine plasmalogen contents in marine invertebrates. This quantification method involves derivatization of ethanolamine glycerophospholipid (EtnGpl) subclasses, alkenylacyl (plasmalogen), diacyl, and alkylacyl subclasses, by enzyme treatment and acetylation, followed by separation and detection by high-performance liquid chromatography (HPLC) with evaporative light-scattering detection (ELSD). This method enabled complete separation of the subclasses, and the limit of detection for plasmalogen was 200 ng (260 pmol). The peak area of plasmalogen by ELSD was unaffected by the degree of unsaturated fatty acids in EtnGpl, in contrast to ultraviolet (UV) detection. Thus, this method enables accurate determination of plasmalogen contents in various species containing marine products possessing abundant polyunsaturated fatty acids (PUFA). The method developed here was applied to marine invertebrates available in Japan. The examined marine invertebrates showed a wide range of plasmalogen contents ranging from 19 to 504 μmol/100 g wet wt. The plasmalogen levels in samples except those of class Cephalopoda and Crustacea were more than 60 mol% of EtnGpl.

  9. Amplification of interference color by using liquid crystal for protein detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Qingdi; Yang, Kun-Lin, E-mail: cheyk@nus.edu.sg [Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore)

    2013-12-09

    Micrometer-sized, periodic protein lines printed on a solid surface cause interference color which is invisible to the naked eye. However, the interference color can be amplified by using a thin layer of liquid crystal (LC) covered on the surface to form a phase diffraction grating. Strong interference color can thus be observed under ambient light. By using the LC-amplified interference color, we demonstrate naked-eye detection of a model protein—immunoglobulin G (IgG). Limit of detection can reach 20 μg/ml of IgG without using any instrumentation. This detection method is potentially useful for the development of low-cost and portable biosensors.

  10. Amplification of interference color by using liquid crystal for protein detection

    International Nuclear Information System (INIS)

    Zhu, Qingdi; Yang, Kun-Lin

    2013-01-01

    Micrometer-sized, periodic protein lines printed on a solid surface cause interference color which is invisible to the naked eye. However, the interference color can be amplified by using a thin layer of liquid crystal (LC) covered on the surface to form a phase diffraction grating. Strong interference color can thus be observed under ambient light. By using the LC-amplified interference color, we demonstrate naked-eye detection of a model protein—immunoglobulin G (IgG). Limit of detection can reach 20 μg/ml of IgG without using any instrumentation. This detection method is potentially useful for the development of low-cost and portable biosensors

  11. Establishment of neural network model for flow blockage detection system in a liquid metal reactor

    International Nuclear Information System (INIS)

    Seong, S.H.; Jeong, H.Y.; Hur, S.; Kim, S.O.

    2006-01-01

    Full text: Full text: A partial flow blockage in an assembly of a liquid metal reactor could result in a cooling deficiency of the core. Since the flow blockage is occurred in the fuel assembly, it is difficult to directly detect the flow blockage in an assembly. However, the coolant temperature beyond the exit of the assemblies was fluctuated by temperature distortion in the core. Due to the change of the temperature profile at the exit of the partially blocked assembly, the characteristics of the temperature fluctuations in the upper plenum should be changed when an assembly was partially blocked. For examining the characteristics of the temperature fluctuations in the upper plenum, we have numerically analyzed the fluctuating temperature field in the upper plenum beyond the exit of the assemblies by using a LES turbulence model in CFX-5.7 code. After analyzing the characteristics of the temperature fluctuations in the upper plenum with various block conditions, we have studied their statistical characteristics like root mean square, standard deviation and skewness. Then, we have developed the neural network model for detecting a partial flow blockage of an assembly with the changes of root mean square, the standard deviation and the skewness of the fluctuation data as inputs and the size and the location of blockage conditions as outputs. Through validating the neural network model, we supposed that the developed neural network model should be a good alternative to detect the partial flow blockage in an assembly of a liquid metal reactor

  12. Pseudospark switches

    International Nuclear Information System (INIS)

    Billault, P.; Riege, H.; Gulik, M. van; Boggasch, E.; Frank, K.

    1987-01-01

    The pseudospark discharge is bound to a geometrical structure which is particularly well suited for switching high currents and voltages at high power levels. This type of discharge offers the potential for improvement in essentially all areas of switching operation: peak current and current density, current rise, stand-off voltage, reverse current capability, cathode life, and forward drop. The first pseudospark switch was built at CERN at 1981. Since then, the basic switching characteristics of pseudospark chambers have been studied in detail. The main feature of a pseudospark switch is the confinement of the discharge plasma to the device axis. The current transition to the hollow electrodes is spread over a rather large surface area. Another essential feature is the easy and precise triggering of the pseudospark switch from the interior of the hollow electrodes, relatively far from the main discharge gap. Nanosecond delay and jitter values can be achieved with trigger energies of less than 0.1 mJ, although cathode heating is not required. Pseudospark gaps may cover a wide range of high-voltage, high-current, and high-pulse-power switching at repetition rates of many kilohertz. This report reviews the basic researh on pseudospark switches which has been going on at CERN. So far, applications have been developed in the range of thyratron-like medium-power switches at typically 20 to 40 kV and 0.5 to 10 kA. High-current pseudospark switches have been built for a high-power 20 kJ pulse generator which is being used for long-term tests of plasma lenses developed for the future CERN Antiproton Collector (ACOL). The high-current switches have operated for several hundred thousand shots, with 20 to 50 ns jitter at 16 kV charging voltage and more than 100 kA peak current amplitude. (orig.)

  13. Determination of bixin and norbixin in meat using liquid chromatography and photodiode array detection.

    Science.gov (United States)

    Noppe, H; Abuin Martinez, S; Verheyden, K; Van Loco, J; Companyo Beltran, R; De Brabander, H F

    2009-01-01

    The development of an analytical method that enables routine analysis of annatto dye, specifically bixin and norbixin, in meat tissue is described. Liquid-solid extraction was carried out using acetonitrile. Analysis was by HPLC with photodiode array detection using two fixed wavelengths (458 and 486 nm). The possibilities of ion trap mass spectrometry (MS) were also assessed. Method performance characteristics, according to Commission Decision 2002/657/EC, were determined, with recoveries between 99 and 102% and calibration curves being linear in the 0.5-10 mg kg(-1) range. The limit of quantification was 0.5 mg kg(-1).

  14. Optical computer switching network

    Science.gov (United States)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  15. Switching antidepressants

    African Journals Online (AJOL)

    depressive disorder, with response rates of 50-60%. Switching within or between classes of antidepressants is often required in patients with an insufficient response to SSRIs.12 Because they share a similar mechanism of action, the immediate substitution of one SSRI for another is probably the easiest switching option.

  16. Amino acid detection using fluoroquinolone–Cu{sup 2+} complex as a switch-on fluorescent probe by competitive complexation without derivatization

    Energy Technology Data Exchange (ETDEWEB)

    Farokhcheh, Alireza; Alizadeh, Naader, E-mail: alizaden@modares.ac.ir

    2014-01-15

    In this work, we describe the use of fluoroquinolone–Cu{sup 2+} complex as a competitive switch-on fluorescence probe for amino acid determination without derivatization. The fluorescence intensity of this probe, which has been reduced due to effective quenching by Cu{sup 2+} ion, increases drastically by an addition of amino acid (glycine, phenylalanine, sarcosine, aspargine, alanine, proline, arginine, aspartic acid, glutamic acid, lysine, leucine and isoleucine). The overall stability constants of Cu{sup 2+} ion complexes with amino acids were determined by fluorometric titration of fluoroquinolone-Cu{sup 2+} complex with the amino acid solution. Furthermore, the probe shows high calibration sensitivity toward aspartic acid. The fluorescence signal depends linearly on the amino acid concentration within the range of concentration from 1.2×10{sup −7} to 1.1×10{sup −5} mol L{sup −1} for aspartic acid. The detection limit was found 2.7×10{sup −8} mol L{sup −1} with the relative standard deviation (RSD%) about 2.1% (five replicate). -- Highlights: • Amino acids are detected by using fluoroquinolone–Cu{sup 2+} complex as fluorescent probe. • Amino acids were detected based on a competitive complexation reaction. • Probe has been able to recognize amino acids through switch-on fluorescence behavior. • Ultra-trace level of aspartic and glutamic acid is determined without derivatization.

  17. Determination of parabens using two microextraction methods coupled with capillary liquid chromatography-UV detection.

    Science.gov (United States)

    Chen, Chen-Wen; Hsu, Wen-Chan; Lu, Ya-Chen; Weng, Jing-Ru; Feng, Chia-Hsien

    2018-02-15

    Parabens are common preservatives and environmental hormones. As such, possible detrimental health effects could be amplified through their widespread use in foods, cosmetics, and pharmaceutical products. Thus, the determination of parabens in such products is of particular importance. This study explored vortex-assisted dispersive liquid-liquid microextraction techniques based on the solidification of a floating organic drop (VA-DLLME-SFO) and salt-assisted cloud point extraction (SA-CPE) for paraben extraction. Microanalysis was performed using a capillary liquid chromatography-ultraviolet detection system. These techniques were modified successfully to determine four parabens in 19 commercial products. The regression equations of these parabens exhibited good linearity (r 2 =0.998, 0.1-10μg/mL), good precision (RSD<5%) and accuracy (RE<5%), reduced reagent consumption and reaction times (<6min), and excellent sample versatility. VA-DLLME-SFO was also particularly convenient due to the use of a solidified extract. Thus, the VA-DLLME-SFO technique was better suited to the extraction of parabens from complex matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The performance of spatially offset Raman spectroscopy for liquid explosive detection

    Science.gov (United States)

    Loeffen, Paul W.; Maskall, Guy; Bonthron, Stuart; Bloomfield, Matthew; Tombling, Craig; Matousek, Pavel

    2016-10-01

    Aviation security requirements adopted in 2014 require liquids to be screened at most airports throughout Europe, North America and Australia. Cobalt's unique Spatially Offset Raman Spectroscopy (SORS™) technology has proven extremely effective at screening liquids, aerosols and gels (LAGS) with extremely low false alarm rates. SORS is compatible with a wide range of containers, including coloured, opaque or clear plastics, glass and paper, as well as duty-free bottles in STEBs (secure tamper-evident bags). Our award-winning Insight range has been specially developed for table-top screening at security checkpoints. Insight systems use our patented SORS technology for rapid and accurate chemical analysis of substances in unopened non-metallic containers. Insight100M™ and the latest member of the range - Insight200M™ - also screen metallic containers. Our unique systems screen liquids, aerosols and gels with the highest detection capability and lowest false alarm rates of any ECAC-approved scanner, with several hundred units already in use at airports including eight of the top ten European hubs. This paper presents an analysis of real performance data for these systems.

  19. Detection of airborne Legionella while showering using liquid impingement and fluorescent in situ hybridization (FISH).

    Science.gov (United States)

    Deloge-Abarkan, Magali; Ha, Thi-Lan; Robine, Enric; Zmirou-Navier, Denis; Mathieu, Laurence

    2007-01-01

    Aerosols of water contaminated with Legionella bacteria constitute the only mode of exposure for humans. However, the prevention strategy against this pathogenic bacteria risk is managed through the survey of water contamination. No relationship linked the Legionella bacteria water concentration and their airborne abundance. Therefore, new approaches in the field of the metrological aspects of Legionella bioaerosols are required. This study was aimed at testing the main principles for bioaerosol collection (solid impaction, liquid impingement and filtration) and the in situ hybridization (FISH) method, both in laboratory and field assays, with the intention of applying such methodologies for airborne Legionella bacteria detection while showering. An aerosolization chamber was developed to generate controlled and reproducible L. pneumophila aerosols. This tool allowed the identification of the liquid impingement method as the most appropriate one for collecting airborne Legionella bacteria. The culturable fraction of airborne L. pneumophila recovered with the liquid impingement principle was 4 and 700 times higher compared to the impaction and filtration techniques, respectively. Moreover, the concentrations of airborne L. pneumophila in the impinger fluid were on average 7.0 x 10(5) FISH-cells m(-3) air with the fluorescent in situ hybridization (FISH) method versus 9.0 x 10(4) CFU m(-3) air with the culture method. These results, recorded under well-controlled conditions, were confirmed during the field experiments performed on aerosols generated by hot water showers in health institutions. This new approach may provide a more accurate characterization of aerobiocontamination by Legionella bacteria.

  20. Epidemiological trends for hospital admissions for acute rotavirus gastroenteritis in Belgium following the introduction of routine rotavirus vaccination and the subsequent switch from lyophilized to liquid formulation of Rotarix™.

    Science.gov (United States)

    Raes, M; Strens, D; Kleintjens, J; Biundo, E; Morel, T; Vyse, A

    2016-10-01

    This study describes epidemiological trends for acute rotavirus gastroenteritis (RVGE) in Belgium in children aged ⩽5 years during the period June 2007 to May 2014 after the introduction of routine rotavirus (RV) vaccination. This period encompassed the switch from lyophilized to the liquid formulation of Rotarix™ (GlaxoSmithKline, Belgium) in August 2011. Uptake of RV vaccine remained consistently high throughout the study period with Rotarix the brand most often used. RV was present in 9% (1139/12 511) of hospitalized cases with acute gastroenteritis included in the study. Epidemiological trends for hospital admissions for RVGE remained consistent throughout the study period, with no evidence of any change associated with the switch from lyophilized to liquid formulation of Rotarix. This suggests both formulations perform similarly, with the liquid formulation not inferior regarding ability to reduce hospital admissions for acute RVGE in children aged ⩽5 years. A strong seasonal effect was observed with most RVGE occurring in the winter months but with some variability in intensity, with highest incidence found in those aged 6-24 months. The main observation was the decreased number of hospital admissions for RVGE in Belgium that occurred during winter 2013/2014.

  1. Gluten Detection and Speciation by Liquid Chromatography Mass Spectrometry (LC-MS/MS

    Directory of Open Access Journals (Sweden)

    Stephen Lock

    2013-12-01

    Full Text Available Liquid chromatography tandem mass spectrometry (LC-MS/MS has been used historically in proteomics research for over 20 years. However, until recently LC-MS/MS has only been routinely used in food testing for small molecule contaminant detection, for example pesticide and veterinary residue detection, and not as a replacement of microbiological food testing methods, specifically allergen analysis. Over the last couple of years, articles have started to be published which describe the detection of allergens by LC-MS/MS. In this article we will describe how LC-MS/MS can be applied in the area of gluten detection and how it can be used to specifically differentiate the species of gluten used in food, where specific markers for each variety of gluten can be simultaneously acquired and detected at the same time. The article will discuss the effect of variety on the peptide response observed from different wheat grain varieties and will describe the sample preparation protocol which is essential for generating the peptide markers used for speciation.

  2. Liquid chromatography coupled to tandem mass spectrometry for detecting ten allergens in complex and incurred foodstuffs.

    Science.gov (United States)

    Planque, M; Arnould, T; Dieu, M; Delahaut, P; Renard, P; Gillard, N

    2017-12-29

    Food allergy is a considerable heath problem, as undesirable contaminations by allergens during food production are still widespread and may be dangerous for human health. To protect the population, laboratories need to develop reliable analytical methods in order to detect allergens in various food products. Currently, a large majority of allergen-related food recalls concern bakery products. It is therefore essential to detect allergens in unprocessed and processed foodstuffs. In this study, we developed a method for detecting ten allergens in complex (chocolate, ice cream) and processed (cookie, sauce) foodstuffs, based on ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Using a single protocol and considering a signal-to-noise ratio higher than 10 for the most abundant multiple reaction monitoring (MRM) transition, we were able to detect target allergens at 0.5mg/kg for milk proteins, 2.5mg/kg for peanut, hazelnut, pistachio, and cashew proteins, 3mg/kg for egg proteins, and 5mg/kg for soy, almond, walnut, and pecan proteins. The ability of the method to detect 10 allergens with a single protocol in complex and incurred food products makes it an attractive alternative to the ELISA method for routine laboratories. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Rapid determination of ampicillin in bovine milk by liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Ang, C.Y.W.; Luo, Wenhong [National Center for Toxicological Research, Jefferson, AR (United States)

    1997-01-01

    A rapid and sensitive liquid chromatographic (LC) method was developed for the determination of ampicillin residues in raw bovine milk, processed skim milk, and pasteurized, homogenized whole milk with vitamin D. Milk samples were deproteinized with trichloroacetic acid (TCA) and acetonictrile. After centrifugation, the clear supernatant was reacted with formaldehyde and TCA under heat. The major fluorescent derivative of ampicillin was then determined by reversed-phase LC with fluorescence detection. Average recoveries of ampicillin fortified at 5, 10, and 20 ppb (ng/mL) were all >85% with coefficients of variation <10%. Limits of detection ranged from 0.31 to 0.51 ppb and limits of quantitation, from 0.66 to 1.2 ppb. After appropriate validation, this method should be suitable for rapid analysis of milk for ampicillin residues at the tolerance level of 10 ppb. 16 refs., 4 figs., 3 tabs.

  4. Liquid chromatography-electrochemical detection of furazolidone and metabolite in extracts of incurred tissues.

    Science.gov (United States)

    Parks, O W; Kubena, L F

    1990-01-01

    One-day-old chicks were raised to maturity on a diet fortified with 0.0055% furazolidone. Analyses of tissue extracts by a liquid chromatographic-electrochemical detection screening procedure for nitro-containing drugs disclosed, in addition to the parent drug, an unidentified metabolite in the liver and breast tissue of the mature birds sacrificed while on the fortified feed. No evidence of residues of the drug or metabolite was found in birds removed from the medicated feed 48 h prior to sacrifice. In view of the rapid in vivo and postmortem metabolism of the parent drug in liver tissue, the metabolite can serve as an alternative means of detecting furazolidone residues in chicken tissues.

  5. A liquid phase blocking ELISA for the detection of antibodies against infectious bronchitis virus

    Directory of Open Access Journals (Sweden)

    Cardoso T.C.

    1999-01-01

    Full Text Available A liquid phase blocking ELISA (LPB-ELISA was developed for the detection and measurement of antibodies against infectious bronchitis virus (IBV. The purified and nonpurified virus used as antigen, the capture and detector antibodies, and the chicken hyperimmune sera were prepared and standardized for this purpose. A total of 156 sera from vaccinated and 100 from specific pathogen-free chickens with no recorded contact with the virus were tested. The respective serum titers obtained in the serum neutralization test (SNT were compared with those obtained in the LPB-ELISA. There was a high correlation (r2 = 0.8926 between the two tests. The LPB-ELISA represents a single test suitable for the rapid detection of antibodies against bronchitis virus in chicken sera, with good sensitivity (88%, specificity (100% and agreement (95.31%.

  6. Automatic Laser Light Detection and Filtering Using a Liquid Crystal Lyot Filter

    Science.gov (United States)

    Rees, S.; Staromlynska, J.

    A device which acts as both a simple cw laser warner and anti-dazzle protection device has been designed and tested. The design is based on a single stage, double element, tunable liquid crystal Lyot filter. Laboratory tests have shown that the detection sensitivity of the device for monochromatic cw radiation is approximately 43×10-9 W/cm2 and that the achievable contrast ratio is greater than 100:1 Automatic detection and filtering of a cw laser source has been demonstrated. Results indicate that the algorithm to automatically filter the laser radiation works well and that the extinction obtained is good. Factors which affect the contrast ratio are discussed and improved device design suggested.

  7. Detecting solid-liquid interface properties with mechanical slip modelling for quartz crystal microbalance operating in liquid

    International Nuclear Information System (INIS)

    Lu, F; Lee, H P; Lim, S P

    2004-01-01

    Quartz crystal microbalances (QCMs) provide sensitive probes for changes at solid-solid or solid-liquid interfaces. It is essential to obtain a physical insight into the details of the interface loading mechanism to interpret the observed behaviour leading to fresh applications of AT-cut quartz resonators. In this work, a mechanical slip model of the interface between a quartz plate and a viscoelastic liquid is presented to replace the continuous displacement assumption. The electrical impedance of a compounded quartz crystal resonator is expressed as a function of the properties of liquid, and the quartz and the strength of contact attraction between the solid and liquid. The interfacial slip parameter between the solid and liquid, which is defined as the displacement transmission from solid particles to liquid bottom particles, is explicitly calculated from the complex attraction strength between the liquid and solid. Comparisons of the physical slip model with other interfacial modes used in the QCM are presented, including the continuous mode and the transmission mode based on the friction force interface. The explicit expression of the slip parameter is presented, and the influence of interfacial slip on QCM measurements is discussed with numerical results. A detailed physical description of the solid-liquid interfacial is useful for exploring fresh ideas for the use of the QCM in biological industry. A new approach by using the slip parameter measured with QCM is proposed to determine the attraction strength between the particles of a viscous liquid and solid particles. The experimental data in the literatures for a hydrophilic-coated sensor and a hydrophobic-coated sensor are used for the numerical examples. It is found that the imaginary part of the interactive strength of these two types of sensor is almost the same. The real part of the interactive strength contributes significantly to distinguish the different interface conditions for these two types of

  8. Comparison of air-agitated liquid-liquid microextraction technique and conventional dispersive liquid-liquid micro-extraction for determination of triazole pesticides in aqueous samples by gas chromatography with flame ionization detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Mogaddam, Mohammad Reza Afshar; Aghdam, Abdollah Abdollahi

    2013-07-26

    Two micro-extraction methods, air-agitated liquid-liquid microextraction (AALLME) and dispersive liquid-liquid microextraction (DLLME), have been compared with each other by applying them for the analysis of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole and triticonazole) in aqueous samples by gas chromatography with flame ionization detection (GC-FID). In the AALLME method, which excludes any disperser solvent, much less volume of organic solvent is used. In order to form fine and dispersed organic droplets in the aqueous phase, the mixture of aqueous sample solution and extraction solvent is repeatedly aspirated and dispensed with a syringe. In the DLLME method, an appropriate mixture of extraction solvent and disperser solvent is rapidly injected by a syringe into the aqueous sample. Effect of the pertinent experimental factors on DLLME (i.e. identity and volume of the extraction and disperser solvents and ionic strength) and on AALLME (identity and volume of the extraction solvent, number of agitations, and ionic strength) were investigated. Under optimal conditions, limits of detection for the five target pesticides obtained by AALLME-GC-FID and DLLME-GC-FID ranged from 0.20 to 1.1ngmL(-1) and 1.9 to 5.9ngmL(-1), respectively. The relative standard deviations (RSDs, n=5) were in the range of 1-4% and 3-5% with the enrichment factors of 449-504 and 79-143 for AALLME-GC-FID and DLLME-GC-FID, respectively. Both of the compared methods are simple, fast, efficient, inexpensive and can be applied to the analysis of the five pesticides in different aqueous samples in which penconazole and hexaconazole were found. For spiked samples, the recoveries were in the ranges of 92-105%, and 92-104% for AALLME and DLLME, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Detection of supernova neutrinos in the liquid-scintillator experiment LENA

    International Nuclear Information System (INIS)

    Winter, Jurgen Michael Albrecht

    2014-01-01

    The LENA project (Low-Energy Neutrino Astronomy) is a planned large-volume liquid-scintillator detector. The good energy resolution, low-energy threshold, and its large mass allow to perform real-time spectroscopy of low-energy neutrinos with high statistics. This is especially beneficial for the observation of rare events such as a galactic core-collapse supernova. In a liquid scintillator, interactions by different particle types cause different scintillation light pulse shapes. They can be used to identify proton recoils induced by neutrino-proton scattering from supernova neutrinos or by cosmogenic knock-out neutrons. In order to evaluate the performance of the detector, a precise characterization of the liquid scintillator is necessary. In the course of this work, an experiment has been set up at the Maier-Leibnitz-Laboratorium in Garching in order to determine the pulse shape of proton and electron recoils in different liquid-scintillator mixtures. Neutrons produced via 11 B(p,n) 11 C or an americiumberyllium source were used to induce proton recoils. Compton scattering of simultaneously emitted γs provided information on the electron recoils. A time-of-flight measurement allows for an easy identification of neutron and γ induced events and thus effective background reduction. The tail-to-total and the Gatti method are used in order to determine the energy-dependent discrimination power of proton and electron recoils in liquid scintillator. Combining both methods, a proton recoil identification efficiency of (99.70±0.05)% can be achieved between 1-1.5 MeV, while suppressing 99% of the γ induced recoils for the probable liquid scintillator mixture for LENA, linear alkylbenzene (LAB) as solvent and 3 g/l 2,5-diphenyloxazole (PPO) and 20mg/l 1,4-bis-(o-methylstyryl)-benzole (bisMSB) as fluors. Moreover, the decay constants τ i and the respective amplitudes n i are determined for various liquid scintillator mixtures. It can be observed that the decay times

  10. Magnetic switching

    International Nuclear Information System (INIS)

    Kirbie, H.C.

    1989-01-01

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs

  11. Rapid detection of economic adulterants in fresh milk by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Abernethy, Grant; Higgs, Kerianne

    2013-05-03

    A method to aid in the detection of the economically driven adulteration of fresh milk with a range of small, nitrogen containing compounds, including melamine, ammeline, ammelide, cyanuric acid, allantoin, thiourea, urea, biuret, triuret, semicarbazide, aminotriazine, 3- and 4-aminotriazole, cyanamide, dicyandiamide, guanidine, choline, hydroxyproline, nitrate, and a range of amino acids, has been developed. (15)N2-Urea is used as an internal standard. The adulteration of milk with exogenous urea has previously been difficult to detect because of the variation in the naturally occurring levels of urea in milk. However, by monitoring the contaminants biuret and triuret, which comprise up to 1% of synthetic urea, the adulteration of milk with urea-based fertilizer can be detected. We estimate that to be economically viable, adulteration of the order of 90-4000ppm of the above adulterants would need to be added to fresh milk. For most of the compounds, an arbitrary detection threshold of 2ppm is therefore more than sufficient. For biuret, a lower detection threshold, better than 0.5ppm, is desirable and the sensitivity for biuret and triuret can be improved by the post-column addition of lithium to create lithium adducts under electrospray ionisation. Sample handling involves a two-step solvent precipitation method that is deployed in a 96-well plate format, and the hydrophilic interaction liquid chromatography uses a rapid gradient (1.2min). Three separate injections, to detect the positively charged compounds, the negatively charged compounds and amino acids and finally the lithium adducts, are used. This rapid and qualitative survey method may be deployed as a second tier screening method to quickly reduce sample numbers indicated as irregular by an FTIR based screening system, and to direct analysis to appropriate quantification methods. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Determination of betaine, l-carnitine, and choline in human urine using a self-packed column and column-switching ion chromatography with nonsuppressed conductivity detection.

    Science.gov (United States)

    Wei, Dan; Liu, Junwei; Guo, Ming; Zhu, Yan

    2017-11-01

    A simple method for the determination of betaine, l-carnitine, and choline in human urine was developed based on column-switching ion chromatography coupled with nonsuppressed conductivity detection by using a self-packed column. A pretreatment column (50 mm × 4.6 mm, id) packed with poly(glycidyl methacrylate-divinylbenzene) microspheres was used for the extraction and cleanup of analytes. Chromatographic separation was achieved within 10 min on a cationic exchange column (150 mm × 4.6 mm, id) using maleic anhydride modified poly(glycidyl methacrylate-divinylbenzene) as the particles for packing. The detection was performed by ion chromatography with nonsuppressed conductivity detection. Parameters including column-switching time, eluent type, flow rates of eluent, and interfering effects were optimized. Linearity (r 2 ≥ 0.99) was obtained for the concentration range of 0.50-100, 0.75-100, and 0.25-100 μg/mL for betaine, l-carnitine, and choline, respectively. Detection limits were 0.12, 0.20, and 0.05 μg/mL for betaine, l-carnitine, and choline, respectively. The intra- and interday accuracy and precision for all quality controls were within ±10.11%. Satisfactory recovery was observed between 92.5 and 105.0%. The validated method was successfully applied for the determination of betaine, l-carnitine, and choline in urine samples from healthy people. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Adhesive liquid core optical fibers for crack detection and repairs in polymer and concrete matrices

    Science.gov (United States)

    Dry, Carolyn M.

    1995-04-01

    This work is an investigation into the feasibility of using liquid core optical fibers for the detection and self repair of cracking in cement or polymer materials generated by dynamic or static loading. These experiments rely on our current research sponsored by the National Science Foundation. It combines that work on the concept of internal adhesive delivery from hollow fibers for repair with nondestructive fiber optic analysis of the crack localization and volume within the same system. The need to monitor the internal state of civil structures and materials is great. Existing instrumentation techniques that mainly rely on magnetism, electricity, or stress gauges are limited if used for remote measurements in concrete or composites. They are sensitive to electrical magnetic noises and they degrade in the environment over time. Optical fibers are attractive because they are immune to electromagnetic interference and are sensitive over long distances. The combination of the ability to remotely measure crack occurrence in real time and determine the location and volume of crack damage in the matrix is unique in the field of optic sensors (or any sensors in general). The combination of this with crack repair, rebonding of any detached or broken fibers, and replenishment of liquid core chemicals, when necessary, make this a potentially powerful sensing and repair tool. Work on this research topic of the combination sponsored by the University of Illinois, looks very promising as a rapid innovative advance.

  14. Ultrasensitive quartz crystal microbalance sensors for detection of M13-Phages in liquids.

    Science.gov (United States)

    Uttenthaler, E; Schräml, M; Mandel, J; Drost, S

    2001-12-01

    Quartz crystal microbalance (QCM) sensors are widely used for determining liquid properties or probing interfacial processes. For some applications the sensitivity of the QCM sensors typically used (5-20 MHz) is limited compared with other biosensor methods. In this study ultrasensitive QCM sensors with resonant frequencies from 39 to 110 MHz for measurements in the liquid phase are presented. The fundamental sensor effect of a QCM is the decrease of the resonant frequency of an oscillating quartz crystal due to the binding of mass on a coated surface during the measurement. The sensitivity of QCM sensors increases strongly with an increasing resonant frequency and, therefore, with a decreasing thickness of the sensitive area. The new kind of ultrasensitive QCM sensors used in this study is based on chemically milled shear mode quartz crystals which are etched only in the center of the blank, forming a thin quartz membrane with a thick, mechanically stable outer ring. An immunoassay using a virus specific monoclonal antibody and a M13-Phage showed an increase in the signal to noise ratio by a factor of more than 6 for 56 MHz quartz crystals compared with standard 19 MHz quartz crystals, the detection limit was improved by a factor of 200. Probing of acoustic properties of glycerol/water mixtures resulted in an increase in sensitivity, which is in very good agreement with theory. Chemically milled QCM sensors strongly improve the sensitivity in biosensing and probing of acoustic properties and, therefore, offer interesting new application fields for QCM sensors.

  15. Parallel segmented outlet flow high performance liquid chromatography with multiplexed detection

    Energy Technology Data Exchange (ETDEWEB)

    Camenzuli, Michelle [Australian Centre for Research on Separation Science (ACROSS), School of Science and Health, University of Western Sydney (Parramatta), Sydney, NSW (Australia); Terry, Jessica M. [Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216 (Australia); Shalliker, R. Andrew, E-mail: r.shalliker@uws.edu.au [Australian Centre for Research on Separation Science (ACROSS), School of Science and Health, University of Western Sydney (Parramatta), Sydney, NSW (Australia); Conlan, Xavier A.; Barnett, Neil W. [Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216 (Australia); Francis, Paul S., E-mail: paul.francis@deakin.edu.au [Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216 (Australia)

    2013-11-25

    Graphical abstract: -- Highlights: •Multiplexed detection for liquid chromatography. •‘Parallel segmented outlet flow’ distributes inner and outer portions of the analyte zone. •Three detectors were used simultaneously for the determination of opiate alkaloids. -- Abstract: We describe a new approach to multiplex detection for HPLC, exploiting parallel segmented outlet flow – a new column technology that provides pressure-regulated control of eluate flow through multiple outlet channels, which minimises the additional dead volume associated with conventional post-column flow splitting. Using three detectors: one UV-absorbance and two chemiluminescence systems (tris(2,2′-bipyridine)ruthenium(III) and permanganate), we examine the relative responses for six opium poppy (Papaver somniferum) alkaloids under conventional and multiplexed conditions, where approximately 30% of the eluate was distributed to each detector and the remaining solution directed to a collection vessel. The parallel segmented outlet flow mode of operation offers advantages in terms of solvent consumption, waste generation, total analysis time and solute band volume when applying multiple detectors to HPLC, but the manner in which each detection system is influenced by changes in solute concentration and solution flow rates must be carefully considered.

  16. [Detecting Thallium in Water Samples using Dispersive Liquid Phase Microextraction-Graphite Furnace Atomic Absorption Spectroscopy].

    Science.gov (United States)

    Zhu, Jing; Li, Yan; Zheng, Bo; Tang, Wei; Chen, Xiao; Zou, Xiao-li

    2015-11-01

    To develope a method of solvent demulsification dispersive liquid phase microextraction (SD-DLPME) based on ion association reaction coupled with graphite furnace atomic absorption spectroscopy (GFAAS) for detecting thallium in water samples. Methods Thallium ion in water samples was oxidized to Tl(III) with bromine water, which reacted with Cl- to form TlCl4-. The ionic associated compound with trioctylamine was obtained and extracted. DLPME was completed with ethanol as dispersive solvent. The separation of aqueous and organic phase was achieved by injecting into demulsification solvent without centrifugation. The extractant was collected and injected into GFAAS for analysis. With palladium colloid as matrix modifier, a two step drying and ashing temperature programming process was applied for high precision and sensitivity. The linear range was 0.05-2.0 microg/L, with a detection limit of 0.011 microg/L. The relative standard derivation (RSD) for detecting Tl in spiked water sample was 9.9%. The spiked recoveries of water samples ranged from 94.0% to 103.0%. The method is simple, sensitive and suitable for batch analysis of Tl in water samples.

  17. A portable liquid crystal-based polarized light system for the detection of organophosphorus nerve gas

    Science.gov (United States)

    He, Feng Jie; Liu, Hui Long; Chen, Long Cong; Xiong, Xing Liang

    2018-03-01

    Liquid crystal (LC)-based sensors have the advantageous properties of being fast, sensitive, and label-free, the results of which can be accessed directly only through the naked eye. However, the inherent disadvantages possessed by LC sensors, such as relying heavily on polarizing microscopes and the difficulty to quantify, have limited the possibility of field applications. Herein, we have addressed these issues by constructing a portable polarized detection system with constant temperature control. This system is mainly composed of four parts: the LC cell, the optics unit, the automatic temperature control unit, and the image processing unit. The LC cell was based on the ordering transitions of LCs in the presence of analytes. The optics unit based on the imaging principle of LCs was designed to substitute the polarizing microscope for the real-time observation. The image processing unit is expected to quantify the concentration of analytes. The results have shown that the presented system can detect dimethyl methyl phosphonate (a stimulant for organophosphorus nerve gas) within 25 s, and the limit of detection is about 10 ppb. In all, our portable system has potential in field applications.

  18. Parallel segmented outlet flow high performance liquid chromatography with multiplexed detection

    International Nuclear Information System (INIS)

    Camenzuli, Michelle; Terry, Jessica M.; Shalliker, R. Andrew; Conlan, Xavier A.; Barnett, Neil W.; Francis, Paul S.

    2013-01-01

    Graphical abstract: -- Highlights: •Multiplexed detection for liquid chromatography. •‘Parallel segmented outlet flow’ distributes inner and outer portions of the analyte zone. •Three detectors were used simultaneously for the determination of opiate alkaloids. -- Abstract: We describe a new approach to multiplex detection for HPLC, exploiting parallel segmented outlet flow – a new column technology that provides pressure-regulated control of eluate flow through multiple outlet channels, which minimises the additional dead volume associated with conventional post-column flow splitting. Using three detectors: one UV-absorbance and two chemiluminescence systems (tris(2,2′-bipyridine)ruthenium(III) and permanganate), we examine the relative responses for six opium poppy (Papaver somniferum) alkaloids under conventional and multiplexed conditions, where approximately 30% of the eluate was distributed to each detector and the remaining solution directed to a collection vessel. The parallel segmented outlet flow mode of operation offers advantages in terms of solvent consumption, waste generation, total analysis time and solute band volume when applying multiple detectors to HPLC, but the manner in which each detection system is influenced by changes in solute concentration and solution flow rates must be carefully considered

  19. Improved liquid chromatography combined with pulsed electrochemical detection for the analysis of etimicin sulfate.

    Science.gov (United States)

    Wu, Yuning; Zhao, Wei; Zhu, Xiaoyue; Wang, Fang; Zhang, Mei; Fan, Xialei; Yuan, Yaozuo; Hu, Changqin; Deng, Xiaolan; Adams, Erwin

    2016-04-01

    This paper describes an improved liquid chromatography method combined with pulsed electrochemical detection for the analysis of etimicin sulfate. In total, 22 impurities could be separated. A TSK-GEL C18 column (250 mm × 4.6 mm i.d., 5 μm) is used, and the mobile phase is composed of 40 mL of acetonitrile and 960 mL of an aqueous solution containing trifluoroacetic acid (15 mL/L), pentafluoropropionic acid (500 μL/L), 50% sodium hydroxide (8 mL/L) and sodium sulfate (1.5 g/L). The pH of the aqueous solution is adjusted to 3.5 with 0.8 M sodium hydroxide. The influence of the different chromatographic parameters on the separation was investigated. A quadruple potential-time waveform was applied to the electrodes of the detection cell. 0.8 M sodium hydroxide was added post column to raise the pH to at least 12 before detection. A central composite experimental design was used to describe the relationship between factors and response values and to establish factorial analysis. Compared to previously published investigations, this improved method shows higher sensitivity, better separation ability and robustness and has been incorporated by the Chinese Pharmacopoeia 2015 for analysis of etimicin sulfate. A number of commercial samples of etimicin sulfate were also analyzed using this method. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. First Detection of Low Energy Electron Neutrinos in Liquid Argon Time Projection Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Corey James [Yale U.

    2016-01-01

    Electron neutrino appearance is the signature channel to address the most pressing questions in neutrino oscillations physics, at both long and short baselines. This includes the search for CP violation in the neutrino sector, which the U.S. flagship neutrino experiment DUNE will address. In addition, the Short Baseline Neutrino Program at Fermilab (MicroBooNE, SBND, ICARUS-T600) searches for new physics, such as sterile neutrinos, through electron neutrino appearance. Liquid argon time projection chambers are the forefront of neutrino detection technology, and the detector of choice for both short and long baseline neutrino oscillation experiments. This work presents the first experimental observation and study of electron neutrinos in the 1-10 GeV range, the essential oscillation energy regime for the above experiments. The systematic uncertainties for an electron neutrino appearance search for the Fermilab Short Baseline Neutrino Program are carefully quantified, and the characterization of separation between electrons and high energy photons is examined.

  1. Machine learning to detect signatures of disease in liquid biopsies - a user's guide.

    Science.gov (United States)

    Ko, Jina; Baldassano, Steven N; Loh, Po-Ling; Kording, Konrad; Litt, Brian; Issadore, David

    2018-01-30

    New technologies that measure sparse molecular biomarkers from easily accessible bodily fluids (e.g. blood, urine, and saliva) are revolutionizing disease diagnostics and precision medicine. Microchip devices can measure more disease biomarkers with better sensitivity and specificity each year, but clinical interpretation of these biomarkers remains a challenge. Single biomarkers in 'liquid biopsy' often cannot accurately predict the state of a disease due to heterogeneity in phenotype and disease expression across individuals. To address this challenge, investigators are combining multiplexed measurements of different biomarkers that together define robust signatures for specific disease states. Machine learning is a useful tool to automatically discover and detect these signatures, especially as new technologies output increasing quantities of molecular data. In this paper, we review the state of the field of machine learning applied to molecular diagnostics and provide practical guidance to use this tool effectively and to avoid common pitfalls.

  2. Measurement of lumefantrine and its metabolite in plasma by high performance liquid chromatography with ultraviolet detection

    DEFF Research Database (Denmark)

    Khalil, Insaf F; Abildrup, Ulla; Alifrangis, Lene H

    2011-01-01

    Artemether-lumefantrine (ARM-LUM) has in recent years become the first-line treatment for uncomplicated malaria in many Sub-Saharan African countries. Vigorous monitoring of the therapeutic efficacy of this treatment is needed. This requires high-quality studies following standard protocols......; ideally, such studies should incorporate measurement of drug levels in the study patients to exclude the possibility that insufficient drug levels explain an observed treatment failure. Several methods for measuring lumefantrine (LUM) in plasma by HPLC are available; however, several of these methods have...... some limitations in terms of high costs and limited feasibility arising from large required sample volumes and demanding sample preparation. Therefore, we set out to develop a simpler reversed phase high performance liquid chromatography (RP-HPLC) method based on UV detection for simultaneous...

  3. Statistical quality assessment and outlier detection for liquid chromatography-mass spectrometry experiments

    Directory of Open Access Journals (Sweden)

    Schulz-Trieglaff Ole

    2009-04-01

    Full Text Available Abstract Background Quality assessment methods, that are common place in engineering and industrial production, are not widely spread in large-scale proteomics experiments. But modern technologies such as Multi-Dimensional Liquid Chromatography coupled to Mass Spectrometry (LC-MS produce large quantities of proteomic data. These data are prone to measurement errors and reproducibility problems such that an automatic quality assessment and control become increasingly important. Results We propose a methodology to assess the quality and reproducibility of data generated in quantitative LC-MS experiments. We introduce quality descriptors that capture different aspects of the quality and reproducibility of LC-MS data sets. Our method is based on the Mahalanobis distance and a robust Principal Component Analysis. Conclusion We evaluate our approach on several data sets of different complexities and show that we are able to precisely detect LC-MS runs of poor signal quality in large-scale studies.

  4. Preliminary validation of high performance liquid chromatography method for detection of methyl-testosterone residue in carp muscle

    Science.gov (United States)

    Jiang, Jie; Lin, Hong; Fu, Xiaoting; Li, Mingming

    2005-07-01

    The use of synthetic anabolic steroid methyltestosterone (MT) as growth promoter is prohibited in China. Validations of analytical methods for MT residue in food and the results obtained have become indispensable. The high performance liquid chromatography (HPLC) method for the detection of MT with liquid-liquid extraction by trichloromethane-methanol in carp muscle tissue was preliminarily validated with reference to the following parameters: recovery (accuracy) at the 1, 5 and l0 mgkg-1 level, between-run and within-run CV values (repeatability, also called relative standard deviation (RSD)) and limit of detection. The recoveries were above 80% and the between-run and within-run CV values below 10% for muscle tissue. The limit of detection was 0.05 mgkg-1.

  5. A Study on the Model of Detecting the Liquid Level of Sealed Containers Based on Kirchhoff Approximation Theory.

    Science.gov (United States)

    Zhang, Bin; Song, Wen-Ai; Wei, Yue-Juan; Zhang, Dong-Song; Liu, Wen-Yi

    2017-06-15

    By simulating the sound field of a round piston transducer with the Kirchhoff integral theorem and analyzing the shape of ultrasound beams and propagation characteristics in a metal container wall, this study presents a model for calculating the echo sound pressure by using the Kirchhoff paraxial approximation theory, based on which and according to different ultrasonic impedance between gas and liquid media, a method for detecting the liquid level from outside of sealed containers is proposed. Then, the proposed method is evaluated through two groups of experiments. In the first group, three kinds of liquid media with different ultrasonic impedance are used as detected objects; the echo sound pressure is calculated by using the proposed model under conditions of four sets of different wall thicknesses. The changing characteristics of the echo sound pressure in the entire detection process are analyzed, and the effects of different ultrasonic impedance of liquids on the echo sound pressure are compared. In the second group, taking water as an example, two transducers with different radii are selected to measure the liquid level under four sets of wall thickness. Combining with sound field characteristics, the influence of different size transducers on the pressure calculation and detection resolution are discussed and analyzed. Finally, the experimental results indicate that measurement uncertainly is better than ±5 mm, which meets the industrial inspection requirements.

  6. A Study on the Model of Detecting the Liquid Level of Sealed Containers Based on Kirchhoff Approximation Theory

    Directory of Open Access Journals (Sweden)

    Bin Zhang

    2017-06-01

    Full Text Available By simulating the sound field of a round piston transducer with the Kirchhoff integral theorem and analyzing the shape of ultrasound beams and propagation characteristics in a metal container wall, this study presents a model for calculating the echo sound pressure by using the Kirchhoff paraxial approximation theory, based on which and according to different ultrasonic impedance between gas and liquid media, a method for detecting the liquid level from outside of sealed containers is proposed. Then, the proposed method is evaluated through two groups of experiments. In the first group, three kinds of liquid media with different ultrasonic impedance are used as detected objects; the echo sound pressure is calculated by using the proposed model under conditions of four sets of different wall thicknesses. The changing characteristics of the echo sound pressure in the entire detection process are analyzed, and the effects of different ultrasonic impedance of liquids on the echo sound pressure are compared. In the second group, taking water as an example, two transducers with different radii are selected to measure the liquid level under four sets of wall thickness. Combining with sound field characteristics, the influence of different size transducers on the pressure calculation and detection resolution are discussed and analyzed. Finally, the experimental results indicate that measurement uncertainly is better than ±5 mm, which meets the industrial inspection requirements.

  7. Coherent spectral amplitude coded label detection for DQPSK payload signals in packet-switched metropolitan area networks

    DEFF Research Database (Denmark)

    Osadchiy, Alexey Vladimirovich; Guerrero Gonzalez, Neil; Jensen, Jesper Bevensee

    2011-01-01

    We report on an experimental demonstration of a frequency swept local oscillator-based spectral amplitude coding (SAC) label detection for DQPSK signals after 40km of fiber transmission. Label detection was performed for a 10.7Gbaud DQPSK signal labeled with a SAC label composed of four-frequency......-frequency tones with 500MHz spectral separation. Successful label detection and recognition is achieved with the aid of digital signal processing that allows for substantial reduction of the complexity of the detection optical front-end....

  8. Detection of warfare agents in liquid foods using the brine shrimp lethality assay.

    Science.gov (United States)

    Lumor, Stephen E; Diez-Gonzalez, Francisco; Labuza, Theodore P

    2011-01-01

    The brine shrimp lethality assay (BSLA) was used for rapid and non-specific detection of biological and chemical warfare agents at concentrations considerably below that which will cause harm to humans. Warfare agents detected include T-2 toxin, trimethylsilyl cyanide, and commercially available pesticides such as dichlorvos, diazinon, dursban, malathion, and parathion. The assay was performed by introducing 50 μL of milk or orange juice contaminated with each analyte into vials containing 10 freshly hatched brine shrimp nauplii in seawater. This was incubated at 28 °C for 24 h, after which mortality was determined. Mortality was converted to probits and the LC(50) was determined for each analyte by plotting probits of mortality against analyte concentration (log(10)). Our findings were the following: (1) the lethal effects of toxins dissolved in milk were observed, with T-2 toxin being the most lethal and malathion being the least, (2) except for parathion, the dosage (based on LC(50)) of analyte in a cup of milk (200 mL) consumed by a 6-y-old (20 kg) was less than the respective published rat LD(50) values, and (3) the BSLA was only suitable for detecting toxins dissolved in orange juice if incubation time was reduced to 6 h. Our results support the application of the BSLA for routine, rapid, and non-specific prescreening of liquid foods for possible sabotage by an employee or an intentional bioterrorist act. Practical Application: The findings of this study strongly indicate that the brine shrimp lethality assay can be adapted for nonspecific detection of warfare agents or toxins in food at any point during food production and distribution.

  9. Predictors of treatment failure and time to detection and switching in HIV-infected Ethiopian children receiving first line anti-retroviral therapy

    Directory of Open Access Journals (Sweden)

    Bacha Tigist

    2012-08-01

    Full Text Available Abstract Background The emergence of resistance to first line antiretroviral therapy (ART regimen leads to the need for more expensive and less tolerable second line drugs. Hence, it is essential to identify and address factors associated with an increased probability of first line ART regimen failure. The objective of this article is to report on the predictors of first line ART regimen failure, the detection rate of ART regime failure, and the delay in switching to second line ART drugs. Methods A retrospective cohort study was conducted from 2005 to 2011. All HIV infected children under the age of 15 who took first line ART for at least six months at the four major hospitals of Addis Ababa, Ethiopia were included. Data were collected, entered and analyzed using Epi info/ENA version 3.5.1 and SPSS version 16. The Cox proportional-hazard model was used to assess the predictors of first line ART failure. Results Data of 1186 children were analyzed. Five hundred seventy seven (48.8% were males with a mean age of 6.22 (SD = 3.10 years. Of the 167(14.1% children who had treatment failure, 70 (5.9% had only clinical failure, 79 (6.7% had only immunologic failure, and 18 (1.5% had both clinical and immunologic failure. Patients who had height for age in the third percentile or less at initiation of ART were found to have higher probability of ART treatment failure [Adjusted Hazard Ratio (AHR, 3.25 95% CI, 1.00-10.58]. Patients who were less than three years old [AHR, 1.85 95% CI, 1.24-2.76], chronic diarrhea after initiation of antiretroviral treatment [AHR, 3.44 95% CI, 1.37-8.62], ART drug substitution [AHR, 1.70 95% CI, 1.05-2.73] and base line CD4 count below 50 cells/mm3 [AHR, 2.30 95% CI, 1.28-4.14] were also found to be at higher risk of treatment failure. Of all the 167 first line ART failure cases, only 24 (14.4% were switched to second line ART with a mean delay of 24 (SD = 11.67 months. The remaining 143 (85.6% cases were diagnosed

  10. Liquid Crystal Enabled Early Stage Detection of Beta Amyloid Formation on Lipid Monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Sadati, Monirosadat [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Apik, Aslin Izmitli [Chemical and Biological Engineering, University of Wisconsin, Madison WI 53706 USA; Armas-Perez, Julio C. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Martinez-Gonzalez, Jose [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Hernandez-Ortiz, Juan P. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Departamento de Materiales y Minerales, Facultad de Minas, Universidad Nacional de Colombia, Sede Medellín, Calle 75 # 79A-51, Bloque M17 Medellín Colombia; Abbott, Nicholas L. [Chemical and Biological Engineering, University of Wisconsin, Madison WI 53706 USA; de Pablo, Juan J. [Institute for Molecular Engineering, University of Chicago, Chicago IL 60637 USA; Argonne National Laboratory, Argonne IL 60439 USA

    2015-09-09

    Liquid crystals (LCs) can serve as sensitive reporters of interfacial events, and this property has been used for sensing of synthetic or biological toxins. Here it is demonstrated that LCs can distinguish distinct molecular motifs and exhibit a specific response to beta-sheet structures. That property is used to detect the formation of highly toxic protofibrils involved in neurodegenerative diseases, where it is crucial to develop methods that probe the early-stage aggregation of amyloidogenic peptides in the vicinity of biological membranes. In the proposed method, the amyloid fibrils formed at the lipid-decorated LC interface can change the orientation of LCs and form elongated and branched structures that are amplified by the mesogenic medium; however, nonamyloidogenic peptides form ellipsoidal domains of tilted LCs. Moreover, a theoretical and computational analysis is used to reveal the underlying structure of the LC, thereby providing a detailed molecular-level view of the interactions and mechanisms responsible for such motifs. The corresponding signatures can be detected at nanomolar concentrations of peptide by polarized light microscopy and much earlier than the ones that can be identified by fluorescence-based techniques. As such, it offers the potential for early diagnoses of neurodegenerative diseases and for facile testing of inhibitors of amyloid formation.

  11. Detection of honey adulteration with starch syrup by high performance liquid chromatography.

    Science.gov (United States)

    Wang, Shaoqing; Guo, Qilei; Wang, Linlin; Lin, Li; Shi, Hailiang; Cao, Hong; Cao, Baosen

    2015-04-01

    According to saccharide profile comparison between starch syrups and pure honeys analysed through high performance liquid chromatography (HPLC), a characteristic peak was found at 15.25 min retention time in HPLC chromatogram of syrup, but no peak was observed at the same retention time in chromatogram of pure honeys. This characteristic peak for syrup was identified as an overlapping peak of oligosaccharides with more than 5 degree of polymerisation (DP) based on HPLC chromatogram comparison between starch syrup and a series of standard mono-, di- and oligosaccharides of 3-7 DP. Additionally syrup content correlated linearly with the height of the characteristic peak of syrup under different slope in two ranges 2.5-7.5% and 10-100%, respectively. Therefore, the characteristic peak at 15.25 min retention time can serve as a syrup indicator in HPLC analysis of the adulterated honeys. This new HPLC method for honey adulteration detection was further applied in an authenticity inspection on more than 100 commercial honeys. In addition to the improved accuracy of honey adulteration detection, the proposed HPLC method was simple, low cost and easy practice for honey product quality control by government department considering the popularity of HPLC device and technology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Liquid detection with InGaAsP semiconductor lasers having multiple short external cavities.

    Science.gov (United States)

    Zhu, X; Cassidy, D T

    1996-08-20

    A liquid detection system consisting of a diode laser with multiple short external cavities (MSXC's) is reported. The MSXC diode laser operates single mode on one of 18 distinct modes that span a range of 72 nm. We selected the modes by setting the length of one of the external cavities using a piezoelectric positioner. One can measure the transmission through cells by modulating the injection current at audio frequencies and using phase-sensitive detection to reject the ambient light and reduce 1/f noise. A method to determine regions of single-mode operation by the rms of the output of the laser is described. The transmission data were processed by multivariate calibration techniques, i.e., partial least squares and principal component regression. Water concentration in acetone was used to demonstrate the performance of the system. A correlation coefficient of R(2) = 0.997 and 0.29% root-mean-square error of prediction are found for water concentration over the range of 2-19%.

  13. Multiresidue determination of quinolone antibacterials in eggs of laying hens by liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Hassouan, M K; Ballesteros, O; Taoufiki, J; Vílchez, J L; Cabrera-Aguilera, M; Navalón, A

    2007-06-01

    An analytical method for the simultaneous determination of seven quinolones (ciprofloxacin, enrofloxacin, danofloxacin, difloxacin, flumequine, oxolinic acid and sarafloxacin) in egg samples of laying hens was developed. Their use is totally prohibited in animals from which eggs are produced for human consumption. Protein precipitation was achieved by addition of acetonitrile and ammonia, removal of acetonitrile with dichloromethane, the quinolones remaining in the basic aqueous extract. The aqueous extract was analysed by liquid chromatography with fluorescence detection (LC-FD). The mobile phase was composed of acetonitrile and 10 mM citrate buffer solution of pH 4.5, with an initial composition of acetonitrile-water (12:88, v/v) and using linear gradient elution. Norfloxacin was used as an internal standard. The limits of detection found were 4-12 ng g(-1). These values were lower than the maximum residue limits (MRLs) established by the European Union for these compounds in different tissues of eggs-producing animals.

  14. Analysis of selected carbonyl oxidation products in wine by liquid chromatography with diode array detection.

    Science.gov (United States)

    Elias, Ryan J; Laurie, V Felipe; Ebeler, Susan E; Wong, Jon W; Waterhouse, Andrew L

    2008-09-19

    A high performance liquid chromatography (HPLC) method for the detection and quantitation of acetaldehyde, glyceraldehyde, pyruvic acid, 2-ketoglutaric acid, and formaldehyde in wine, based on the formation of the 2,4-dinitrophenylhydrazones, is presented. These carbonyl compounds often result from the chemical oxidation of major wine components, and are known to affect flavor and color stability. Their analysis in wine is complicated due to their instability and their tendency to react reversibly with bisulfite to form alpha-hydroxysulfonates. Published methods that break down the sulfonates for the quantitation of total carbonyls in wine involve alkaline hydrolysis of sulfite-bound carbonyls, but we show, for the first time, that this alkaline treatment step significantly increases the concentration of carbonyls during analysis. A solution based on oxygen exclusion is described. The technique offers good specificity, reproducibility (%RSD 0.45-10.6), and limits of detection (1.29-7.53microgL(-1)). The method was successfully used to monitor concentration changes of these compounds in both white and red wines.

  15. Water Pipeline Monitoring and Leak Detection using Flow Liquid Meter Sensor

    Science.gov (United States)

    Rahmat, R. F.; Satria, I. S.; Siregar, B.; Budiarto, R.

    2017-04-01

    Water distribution is generally installed through underground pipes. Monitoring the underground water pipelines is more difficult than monitoring the water pipelines located on the ground in open space. This situation will cause a permanent loss if there is a disturbance in the pipeline such as leakage. Leaks in pipes can be caused by several factors, such as the pipe’s age, improper installation, and natural disasters. Therefore, a solution is required to detect and to determine the location of the damage when there is a leak. The detection of the leak location will use fluid mechanics and kinematics physics based on harness water flow rate data obtained using flow liquid meter sensor and Arduino UNO as a microcontroller. The results show that the proposed method is able to work stably to determine the location of the leak which has a maximum distance of 2 metres, and it’s able to determine the leak location as close as possible with flow rate about 10 litters per minute.

  16. Use of Liquid Chromatography with Electrochemical Detection for the Determination of Antioxidants in Less Common Fruits

    Directory of Open Access Journals (Sweden)

    Zbynek Gazdik

    2008-11-01

    Full Text Available Neurodegenerative disorders (NDD have become the common global health burden over the last several decades. According to World Health Organization (WHO, a staggering 30 million people will be affected by Alzheimer’s disease in Europe and the USA by 2050. Effective therapies in this complex field considering the multitude of symptoms associated with NDD indications, have not been found yet. Based on the results of NDD related studies, prevention appears to be the promise alternative. Antioxidative and anti-inflammatory properties are hypothesized for natural phenolics, a group of plant secondary products that may positively impact neurodegenerative diseases. In these studies, phenolic-rich extracts from less common fruit species: Blue honeysuckle (Lonicera edulis, Turcz. ex. Freyn, Saskatoon berry (Amelanchier alnifolia Nutt., and Chinese hawthorn (Crateagus pinnatifida Bunge were obtained and analyzed to detect neuroprotective substances content and establish a potential therapeutic value. High performance liquid chromatography with electrochemical detection was optimized and further applied on analysis of the extracts of less common fruit species. It was observed that Chinese hawthorn and Blue honeysuckle extracts are potent source of neuroprotective phenolic antioxidants. In accordance the results, it appears that the fruit or formulated products may have the potential for the prevention of neurodegenerative diseases.

  17. Coupling of homogeneous liquid-liquid extraction and dispersive liquid-liquid microextraction for the extraction and preconcentration of polycyclic aromatic hydrocarbons from aqueous samples followed by GC with flame ionization detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Khiavi, Elahe Behboudi; Khorram, Parisa; Mogaddam, Mohammad Reza Afshar

    2017-01-01

    In the present study, a simple and rapid method for the extraction and preconcentration of some polycyclic aromatic hydrocarbons in water samples has been developed. In this method, two sample preparation methods were combined to obtain high extraction recoveries and enrichment factors for sensitive analysis of the selected analytes. In the first stage of the method, a homogeneous solution containing an aqueous solution and cyclohexyl amine is broken by the addition of a salt. After centrifugation, the upper collected phase containing the extracted analytes is subjected to the following dispersive liquid-liquid microextraction method. Rapid injection of the mixture of cyclohexyl amine resulted from the first stage and 1,1,2-trichloroethane (as an extraction solvent) into an acetic acid solution is led to form a cloudy solution. After centrifuging, the fine droplets of the extraction solvent are settled down in the bottom of the test tube, and an aliquot of it is analyzed by gas chromatography. Under the optimum extraction conditions, enrichment factors and limits of detection for the studied analytes were obtained in the ranges of 616-752 and 0.08-0.20 μg/L, respectively. The simplicity, high extraction efficiency, short sample preparation time, low cost, and safety demonstrated the efficiency of this method relative to other approaches. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Detection of Clostridium botulinum in liquid manure and biogas plant wastes.

    Science.gov (United States)

    Neuhaus, Jürgen; Schrödl, Wieland; Shehata, Awad A; Krüger, Monika

    2015-09-01

    Biogas plants have been considered as a source for possible amplification and distribution of pathogenic bacteria capable of causing severe infections in humans and animals. Manure and biogas wastes could be sources for spore-forming bacteria such as Clostridium botulinum. In the present study, 24 liquid manure and 84 biogas waste samples from dairies where the majority of the cows suffered from chronic botulism were investigated for the presence of botulinum neurotoxins (BoNT) and C. botulinum spores. The prevalence of BoNT/A, B, C, D, and E in biogas wastes was 16.6, 8.3, 10.7, 7.1, and 10.8 %, respectively, while in manure, the prevalence was 0.0, 0.0, 0.0, 8.3, and 4.1 %, respectively. After enrichment of samples in reinforced cultural medium, they were tested for C. botulinum BoNT/A, B, C, D, and E using ELISA (indirect C. botulinum detection). The prevalence of C. botulinum type A, B, C, D, and E samples in biogas wastes was 20.2, 15.5, 19, 10.7, and 34.8 %, respectively, while the prevalence in liquid manure was 0.0, 0.0, 0.0, 8.3, and 12.5 %, respectively. In conclusion, the occurrence of BoNT and C. botulinum spores in biogas waste of diseased animals indicates an increased and underestimated hygienic risk. Application of digestates from biogas fermentations as fertilizers could lead to an accumulation of long lifespan spores in the environment and could be a possible health hazard.

  19. High-performance liquid chromatographic determination of levodropropizine in human plasma with fluorometric detection.

    Science.gov (United States)

    Tagliaro, F; Moffa, M; De Battisti, Z; Smith, F P; Gentile, M

    1996-10-11

    The present paper describes a new high-performance liquid chromatographic method with fluorescence detection for the analysis of levodropropizine [S-(-)-3-(4-phenylpiperazin-1-yl)-propane-1,2-diol] (Levotuss), an anti-tussive drug, in human serum and plasma. A reversed-phase separation of levodropropizine was coupled with detection of the native fluorescence of the molecule, using excitation and emission wavelengths of 240 nm and 350 nm respectively. The analytical column was packed with spherical 5 microns poly(styrene-divinylbenzene) particles and the mobile phase was 0.1 M NaH2PO4 pH 3-methanol (70:30, v/v), containing 0.5% (v/v) tetrahydrofuran. For quantitation, p-methoxylevodropropizine was used as the internal standard. Samples of 200 microliters of either serum or plasma were mixed with 200 microliters of 0.1 M Na2HPO4 pH 8.9 and extracted with 5 ml of chloroform-2-propanol (9:1, v/v). The dried residue from the organic extract was redissolved with distilled water and directly injected into the chromatograph. The limit of detection for levodropropizine, in biological matrix, was about 1-2 ng/ml, at a signal-to-noise ratio of 3. The linearity was satisfactory over a range of concentrations from 3 to 1000 ng/ml (r2 = 0.99910); within-day precision tested in the range 5-100 ng/ml as well as day-to-day reproducibility proved acceptable, with relative standard deviations better than 1% in most cases. Interferences from as many as 91 therapeutic or illicit drugs were excluded.

  20. Use of Denaturing High-Performance Liquid Chromatography for Rapid Detection and Identification of Seven Candida Species

    OpenAIRE

    Goldenberg, Oliver; Herrmann, Stefanie; Adam, Thomas; Marjoram, Gina; Hong, George; Göbel, Ulf B.; Graf, Barbara

    2005-01-01

    A novel denaturing high-performance liquid chromatography (DHPLC)-based technique allows rapid high-resolution analysis of PCR products. We used this technique for unequivocal molecular identification of seven Candida species. We show the application of this PCR/DHPLC approach for direct detection and identification of yeast species from blood cultures and for detection of Candida colonization in the gastrointestinal tract of allogeneic transplant patients.

  1. Target-induced structure switching of hairpin aptamers for label-free and sensitive fluorescent detection of ATP via exonuclease-catalyzed target recycling amplification.

    Science.gov (United States)

    Xu, Yunying; Xu, Jin; Xiang, Yun; Yuan, Ruo; Chai, Yaqin

    2014-01-15

    In this work, we described the development of a new label-free, simple and sensitive fluorescent ATP sensing platform based on exonuclease III (Exo III)-catalyzed target recycling (ECTR) amplification and SYBR Green I indicator. The hairpin aptamer probes underwent conformational structure switching and re-configuration in the presence of ATP, which led to catalytic cleavage of the re-configured aptamers by Exo III to release ATP and to initiate the ECTR process. Such ECTR process resulted in the digestion of a significant number of the hairpin aptamer probes, leading to much less intercalation of SYBR Green I to the hairpin stems and drastic suppression of the fluorescence emission for sensitive ATP detection down to the low nanomolar level. Due to the highly specific affinity bindings between aptamers and ATP, the developed method exhibited excellent selectivity toward ATP against other analogous molecules. Besides, our ATP sensing approach used un-modified aptamer probes and could be performed in a "mix-and-detect" fashion in homogenous solutions. All these distinct advantages of the developed method thus made it hold great potential for the development of simple and robust sensing strategies for the detection of other small molecules. © 2013 Elsevier B.V. All rights reserved.

  2. A New Method for Ultrasound Detection of Interfacial Position in Gas-Liquid Two-Phase Flow

    Directory of Open Access Journals (Sweden)

    Fábio Rizental Coutinho

    2014-05-01

    Full Text Available Ultrasonic measurement techniques for velocity estimation are currently widely used in fluid flow studies and applications. An accurate determination of interfacial position in gas-liquid two-phase flows is still an open problem. The quality of this information directly reflects on the accuracy of void fraction measurement, and it provides a means of discriminating velocity information of both phases. The algorithm known as Velocity Matched Spectrum (VM Spectrum is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. It is shown that the proposed technique yields a RMS error between 1.71 and 3.39 and a probability of detection failure and false detection between 0.89% and 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe.

  3. Rapid Analysis of Apolar Low Molecular Weight Constituents in Wood Using High Pressure Liquid Chromatography with Evaporative Light Scattering Detection

    NARCIS (Netherlands)

    Claassen, F.W.; Haar, van de C.; Beek, van T.A.; Dorado, J.; Martinez-Inigo, M.; Sierra-Alvarez, R.

    2000-01-01

    A new high pressure liquid chromatographic method with evaporative light scattering detection was developed for the qualitative and quantitative analysis of apolar, low molecular weight constituents in wood. The wood extractives were obtained by means of a 6 h Soxhlet extraction with acetone. The

  4. Vitamin E composition of some seed oils as determined by High Performance Liquid Chromatography with fluorometric detection

    NARCIS (Netherlands)

    Speek, A.J.; Schrijver, J.; Schreurs, W.H.P.

    1985-01-01

    A high‐performance liquid chromatographic (HPLC) method is described for the simultaneous analysis of E vitamers α‐, and β‐, γ‐ and δ‐tocopherol and α‐tocotrienol in seed oils. After diluting the oils with n‐hexane, E vitamers are separated by HPLC and detected fluorometrically. Standardization is

  5. Sensitive absorption detection for micro-column liquid chromatography by ultraviolet forward-scattering degenerate four-wave mixing.

    NARCIS (Netherlands)

    de Beer, T.; Beso, P.; Velthorst, N.H.; Brinkman, U.A.T.; Gooijer, C.; Hoornweg, G.Ph.

    1999-01-01

    The performance of forward-scattering degenerate four-wave mixing (F-D4WM) in the mid-ultraviolet (UV) region (351nm) as a detection technique for micro-column liquid chromatography (μLC) is studied, using nitro-substituted polycyclic aromatic hydrocarbons (NO

  6. A new method for ultrasound detection of interfacial position in gas-liquid two-phase flow.

    Science.gov (United States)

    Coutinho, Fábio Rizental; Ofuchi, César Yutaka; de Arruda, Lúcia Valéria Ramos; Neves, Flávio; Morales, Rigoberto E M

    2014-05-22

    Ultrasonic measurement techniques for velocity estimation are currently widely used in fluid flow studies and applications. An accurate determination of interfacial position in gas-liquid two-phase flows is still an open problem. The quality of this information directly reflects on the accuracy of void fraction measurement, and it provides a means of discriminating velocity information of both phases. The algorithm known as Velocity Matched Spectrum (VM Spectrum) is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. It is shown that the proposed technique yields a RMS error between 1.71 and 3.39 and a probability of detection failure and false detection between 0.89% and 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe.

  7. Threat detection of liquid explosives and precursors from their x-ray scattering pattern using energy dispersive detector technology

    DEFF Research Database (Denmark)

    Kehres, Jan; Olsen, Ulrik Lund; Lyksborg, Mark

    2017-01-01

    Energy dispersive X-ray diffraction (EDXRD) can be applied for identification of liquid threats in luggage scanning in security applications. To define the instrumental design, the framework for data reduction and analysis and test the performance of the threat detection in various scenarios...

  8. Urinary detection of conjugated and unconjugated anabolic steroids by dilute-and-shoot liquid chromatography-high resolution mass spectrometry.

    Science.gov (United States)

    Tudela, Eva; Deventer, Koen; Geldof, Lore; Van Eenoo, Peter

    2015-02-01

    Anabolic androgenic steroids (AAS) are an important class of doping agents. The metabolism of these substances is generally very extensive and includes phase-I and phase-II pathways. In this work, a comprehensive detection of these metabolites is described using a 2-fold dilution of urine and subsequent analysis by liquid chromatography-high resolution mass spectrometry (LC-HRMS). The method was applied to study 32 different metabolites, excreted free or conjugated (glucuronide or sulfate), which permit the detection of misuse of at least 21 anabolic steroids. The method has been fully validated for 21 target compounds (8 glucuronide, 1 sulfate and 12 free steroids) and 18 out of 21 compounds had detection limits in the range of 1-10 ng mL(-1) in urine. For the conjugated compounds, for which no reference standards are available, metabolites were synthesized in vitro or excretion studies were investigated. The detection limits for these compounds ranged between 0.5 and 18 ng mL(-1) in urine. The simple and straightforward methodology complements the traditional methods based on hydrolysis, liquid-liquid extraction, derivatization and analysis by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Copyright © 2014 John Wiley & Sons, Ltd.

  9. Are the soft, liquid-like structures detected around bacteria by ambient dynamic atomic force microscopy capsules?

    Science.gov (United States)

    Méndez-Vilas, A; Labajos-Broncano, L; Perera-Núñez, J; González-Martín, M L

    2011-05-01

    High-resolution imaging of bacterial capsules by microscopy is of paramount importance in microbiology due to their role in pathogenesis. This is, however, quite a challenging task due to their delicate nature. In this context, recent reports have claimed successful exploitation of the capacity of atomic force microscopy (AFM) for imaging of extremely deformable (even liquid) surfaces under ambient conditions to detect bacterial capsules in the form of tiny amounts of liquid-like substances around bacteria. In order to further explore this supposed capacity of AFM, in this work, three staphylococcal strains have been scrutinized for the presence of capsules using such an AFM-based approach with a phosphate buffer and water as the suspending liquids. Similar results were obtained with the three strains. AFM showed the presence of liquid-like substances identical to those attributed to bacterial capsules in the previous literature. Extensive imaging and chemical analysis point out the central role of the suspending liquid (buffer) in the formation of these substances. The phenomenon has been reproduced even by using nonliving particles, a finding that refutes the biological origin of the liquid-like substances visualized around the cells. Deliquescence of major components of biological buffers, such as K(2)HPO(4), CaCl(2), or HEPES, is proposed as the fundamental mechanism of the formation of these ultrasmall liquid-like structures. Such an origin could explain the high similarity of our results obtained with three very different strains and also the high similarity of these results to others reported in the literature based on other bacteria and suspending liquids. Finally, possible biological/biomedical implications of the presence of these ultrasmall amounts of liquids wrapping microorganisms are discussed.

  10. Detection of 10 sweeteners in various foods by liquid chromatography/tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Chui-Shiang Chang

    2014-09-01

    Full Text Available The analytical method for sweeteners in various food matrixes is very important for food quality control and regulation enforcement. A simple and rapid method for the simultaneous determination of 10 sweeteners [acesulfame potassium (ACS-K, aspartame (ASP, cyclamate (CYC, dulcin (DUL, glycyrrhizic acid (GA, neotame (NEO, neohesperidin dihydrochalcone (NHDC, saccharin (SAC, sucralose (SCL, and stevioside (STV] in various foods by liquid chromatography/tandem mass chromatography (LC–MS/MS was developed. The chromatographic separation was performed on a Phenomenex Luna Phenyl-Hexyl (5 μm, 4.6 mm × 150 mm column with gradient elution of 10 mM ammonium acetate in water and 10 mM ammonium acetate in methanol. The recoveries of the 10 sweeteners were between 75% and 120%, and the coefficients of variation were less than 20%. The limits of quantification were 0.5 μg/kg for NHDC and SCL. For the other sweeteners, the limits of quantification were 0.1 μg/kg. Compared to the traditional high-performance liquid chromatography method, the LC–MS/MS method could provide better sensitivity, higher throughput, enhanced specificity, and more sweeteners analyzed in a single run. The samples included 27 beverages (16 alcoholic and 11 nonalcoholic beverages and 15 pickled foods (1 pickled pepper, 3 candies, and 11 candied fruits. Two remanufactured wines were found to contain 7.2, 8.5 μg/g SAC and 126.5, 123 μg/g CYC, respectively. ACS-K, ASP, SCL, and NEO were detected in five beverages and drinks. The pickled peppers and candied fruits were found to contain SAC, GA, CYC, ASP, STV, NEO, and ACS-K. The wine with sweeteners detected was remanufactured wine, not naturally fermented wine. Therefore, the ingredient label for the sweeteners of remanufactured wine should be regulated by the proper authority for inspection of sweeteners.

  11. Simple determination of betaine, l-carnitine and choline in human urine using self-packed column and column-switching ion chromatography with nonsuppressed conductivity detection.

    Science.gov (United States)

    Wei, Dan; Zhu, Yan; Guo, Ming

    2018-02-01

    A sequential online extraction, clean-up and separation system for the determination of betaine, l-carnitine and choline in human urine using column-switching ion chromatography with nonsuppressed conductivity detection was developed in this work. A self-packed pretreatment column (50 × 4.6 mm, i.d.) was used for the extraction and clean-up of betaine, l-carnitine and choline. The separation was achieved using self-packed cationic exchange column (150 × 4.6 mm, i.d.), followed by nonsuppressed conductivity detection. Under optimized experimental conditions, the developed method presented good analytical performance, with excellent linearity in the range of 0.60-100 μg mL -1 for betaine, 0.75-100 μg mL -1 for l-carnitine and 0.50-100 μg mL -1 for choline, with all correlation coefficients (R 2 ) >0.99 in urine. The limits of detection were 0.15 μg mL -1 for betaine, 0.20 μg mL -1 for l-carnitine and 0.09 μg mL -1 for choline. The intra- and inter-day accuracy and precision for all quality controls were within ±10.32 and ±9.05%, respectively. Satisfactory recovery was observed between 92.8 and 102.0%. The validated method was successfully applied to the detection of urinary samples from 10 healthy people. The values detected in human urine using the proposed method showed good agreement with the measurement reported previously. Copyright © 2017 John Wiley & Sons, Ltd.

  12. Markov Switching Autoregressive Conditional Heteroscedasticity (SWARCH) Model to Detect Financial Crisis in Indonesia Based on Import and Export Indicators

    Science.gov (United States)

    Sugiyanto; Zukhronah, Etik; Susanti, Yuliana; Rahma Dwi, Sisca

    2017-06-01

    A country is said to be a crisis when the financial system is experiencing a disruption that affects systems that can not function efficiently. The performance efficiency of macroeconomic indicators especially in imports and exports can be used to detect the financial crisis in Indonesia. Based on the import and export indicators from 1987 to 2015, the movement of these indicators can be modelled using SWARCH three states. The results showed that SWARCH (3,1) model was able to detect the crisis that occurred in Indonesia in 1997 and 2008. Using this model, it can be concluded that Indonesia is prone to financial crisis in 2016.

  13. Competition-derived FRET-switching cationic conjugated polymer-Ir(III) complex probe for thrombin detection.

    Science.gov (United States)

    Du, Chunnuan; Hu, Yufang; Zhang, Qingqing; Guo, Zhiyong; Ge, Guoping; Wang, Sui; Zhai, Chunyang; Zhu, Mingshan

    2018-02-15

    A novel, label-free and convenient strategy for thrombin assay has been developed based on the fluorescence resonance energy transfer (FRET) from a cationic conjugated polymer (CCP) to Ir(III) complex. The energy donor (CCP) and acceptor (Ir(III) complex) were taken into close proximity through π-π stacking interaction and electrostatic interaction, leading to the occurrence of FRET. However, the introduction of the thrombin aptamer upset the status and blocked the FRET process, but afterwards the reappearance of FRET phenomenon was confirmed by the special binding interaction between aptamer and thrombin, thus achieving the quantitative detection of thrombin. This assay could detect thrombin as low concentration as about 0.05pM and provided a highly specific selectivity among other nonspecific proteins. Moreover, the strategy may allow our platform to provide similar sensitivity toward different targets in an aptamer-structure-independent manner. Furthermore, the assay can be used to detect thrombin in diluted real urine or serum samples with a satisfactory recovery, implying its great potential for rapid detection of thrombin in the clinic. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Theoretical and experimental investigations of ferrofluids for guiding and detecting liquids in the subsurface. FY 1997 annual report

    International Nuclear Information System (INIS)

    Moridis, G.J.; Borglin, S.E.; Oldenburg, C.M.; Becker, A.

    1998-03-01

    Ferrofluids are stable colloidal suspensions of magnetic particles in various carrier liquids with high saturation magnetizations, which can be manipulated in virtually any fashion, defying gravitational or viscous forces in response to external magnetic fields. In this report, the authors review the results of their investigation of the potential of ferrofluids (1) to accurately and effectively guide reactants (for in-situ treatment) or barrier liquids (low-viscosity permeation grouts) to contaminated target zones in the subsurface using electromagnetic forces, and (2) to trace the movement and position of liquids injected in the subsurface using geophysical methods. They investigate the use of ferrofluids to enhance the efficiency of in-situ treatment and waste containment through (a) accurate guidance and delivery of reagent liquids to the desired subsurface contamination targets and/or (b) effective sweeping of the contaminated zone as ferrofluids move from the application point to an attracting magnet/collection point. They also investigate exploiting the strong magnetic signature of ferrofluids to develop a method for monitoring of liquid movement and position during injection using electromagnetic methods. The authors demonstrated the ability to induce ferrofluid movement in response to a magnetic field, and measured the corresponding magnetopressure. They demonstrated the feasibility of using conventional magnetometry for detecting subsurface zones of various shapes containing ferrofluids for tracing liquids injected for remediation or barrier formation. Experiments involving spherical, cylindrical and horizontal slabs showed a very good agreement between predictions and measurements

  15. Theoretical and experimental investigations of ferrofluids for guiding and detecting liquids in the subsurface. FY 1997 annual report

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, G.J.; Borglin, S.E.; Oldenburg, C.M.; Becker, A.

    1998-03-01

    Ferrofluids are stable colloidal suspensions of magnetic particles in various carrier liquids with high saturation magnetizations, which can be manipulated in virtually any fashion, defying gravitational or viscous forces in response to external magnetic fields. In this report, the authors review the results of their investigation of the potential of ferrofluids (1) to accurately and effectively guide reactants (for in-situ treatment) or barrier liquids (low-viscosity permeation grouts) to contaminated target zones in the subsurface using electromagnetic forces, and (2) to trace the movement and position of liquids injected in the subsurface using geophysical methods. They investigate the use of ferrofluids to enhance the efficiency of in-situ treatment and waste containment through (a) accurate guidance and delivery of reagent liquids to the desired subsurface contamination targets and/or (b) effective sweeping of the contaminated zone as ferrofluids move from the application point to an attracting magnet/collection point. They also investigate exploiting the strong magnetic signature of ferrofluids to develop a method for monitoring of liquid movement and position during injection using electromagnetic methods. The authors demonstrated the ability to induce ferrofluid movement in response to a magnetic field, and measured the corresponding magnetopressure. They demonstrated the feasibility of using conventional magnetometry for detecting subsurface zones of various shapes containing ferrofluids for tracing liquids injected for remediation or barrier formation. Experiments involving spherical, cylindrical and horizontal slabs showed a very good agreement between predictions and measurements.

  16. Advanced LWIR hyperspectral sensor for on-the-move proximal detection of liquid/solid contaminants on surfaces

    Science.gov (United States)

    Giblin, Jay P.; Dixon, John; Dupuis, Julia R.; Cosofret, Bogdan R.; Marinelli, William J.

    2017-05-01

    Sensor technologies capable of detecting low vapor pressure liquid surface contaminants, as well as solids, in a noncontact fashion while on-the-move continues to be an important need for the U.S. Army. In this paper, we discuss the development of a long-wave infrared (LWIR, 8-10.5 μm) spatial heterodyne spectrometer coupled with an LWIR illuminator and an automated detection algorithm for detection of surface contaminants from a moving vehicle. The system is designed to detect surface contaminants by repetitively collecting LWIR reflectance spectra of the ground. Detection and identification of surface contaminants is based on spectral correlation of the measured LWIR ground reflectance spectra with high fidelity library spectra and the system's cumulative binary detection response from the sampled ground. We present the concepts of the detection algorithm through a discussion of the system signal model. In addition, we present reflectance spectra of surfaces contaminated with a liquid CWA simulant, triethyl phosphate (TEP), and a solid simulant, acetaminophen acquired while the sensor was stationary and on-the-move. Surfaces included CARC painted steel, asphalt, concrete, and sand. The data collected was analyzed to determine the probability of detecting 800 μm diameter contaminant particles at a 0.5 g/m2 areal density with the SHSCAD traversing a surface.

  17. Occurrence of aflatoxins in peanuts and peanut products determined by liquid chromatography with fluorescence detection

    Directory of Open Access Journals (Sweden)

    Stojanovska-Dimzoska Biljana

    2013-01-01

    Full Text Available Liquid chromatography with fluorescence detection using immunoaffinity column clean-up was a method described for determination of aflatoxins (AFB1, AFB2, AFG1 and AFG2 in peanuts and peanut based products. The validation of the procedure was performed. Good coefficient of correlation was found for all aflatoxins in the range of 0.9993-0.9999. Limit of detection (LOD and limit of quantification (LOQ ranged from 0.003-0.005 mg/kg and 0.009-0.023 mg/kg, respectively, which was acceptable. The mean recovery for total aflatoxins was 88.21%. The method also showed acceptable precision values in the range of 0.171-2.626% at proposed concentration levels for all four aflatoxins. RSDR values (within laboratory reproducibility calculated from the results showed good correlation between two analysts for all aflatoxins and they ranged from 4.93-11.87%. The developed method was applied for the determination of aflatoxins in 27 samples of peanuts and peanut based products. The results showed that 21 peanut samples (77.7% were below LOD of the method. Three samples had positive results over the MRL. There was one extreme value recorded for the total aflatoxins in peanut (289.2 mg/kg and two peanut based products, peanut snack and peanut, with total content of aflatoxins being 16.3 mg/kg and 8.0 mg/kg, respectively. The obtained results demonstrated that the procedure was suitable for the de­termination of aflatoxins in peanuts and peanut based products and it could be implemented for the routine analysis.

  18. Determination of Vitamin C (Ascorbic Acid Using High Performance Liquid Chromatography Coupled with Electrochemical Detection

    Directory of Open Access Journals (Sweden)

    Ondrej Zitka

    2008-11-01

    Full Text Available Vitamin C (ascorbic acid, ascorbate, AA is a water soluble organic compound that participates in many biological processes. The main aim of this paper was to utilize two electrochemical detectors (amperometric – Coulouchem III and coulometric – CoulArray coupled with flow injection analysis for the detection of ascorbic acid. Primarily, we optimized the experimental conditions. The optimized conditions were as follows: detector potential 100 mV, temperature 25 °C, mobile phase 0.09% TFA:ACN, 3:97 (v/v and flow rate 0.13 mL·min-1. The tangents of the calibration curves were 0.3788 for the coulometric method and 0.0136 for the amperometric one. The tangent of the calibration curve measured by the coulometric detector was almost 30 times higher than the tangent measured by the amperometric detector. Consequently, we coupled a CoulArray electrochemical detector with high performance liquid chromatography and estimated the detection limit for AA as 90 nM (450 fmol per 5 μL injection. The method was used for the determination of vitamin C in a pharmaceutical preparations (98 ± 2 mg per tablet, in oranges (Citrus aurantium (varied from 30 to 56 mg/100 g fresh weight, in apples (Malus sp. (varied from 11 to 19 mg/100 g fresh weight, and in human blood serum (varied from 38 to 78 μM. The recoveries were also determined.

  19. Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip.

    Science.gov (United States)

    Blanco, Yolanda; Moreno-Paz, Mercedes; Parro, Victor

    2017-02-07

    Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has relevant health and economic consequences. Many cyanobacterial strains are toxin producers, and only a few cells are necessary to induce irreparable damage to the environment. Therefore, water-body authorities and administrations require rapid and efficient early-warning systems providing reliable data to support their preventive or curative decisions. This manuscript reports an experimental protocol for the in-field detection of toxin-producing cyanobacterial strains by using an antibody microarray chip with 17 antibodies (Abs) with taxonomic resolution (CYANOCHIP). Here, a multiplex fluorescent sandwich microarray immunoassay (FSMI) for the simultaneous monitoring of 17 cyanobacterial strains frequently found blooming in freshwater ecosystems, some of them toxin producers, is described. A microarray with multiple identical replicates (up to 24) of the CYANOCHIP was printed onto a single microscope slide to simultaneously test a similar number of samples. Liquid samples can be tested either by direct incubation with the antibodies (Abs) or after cell concentration by filtration through a 1- to 3-μm filter. Solid samples, such as sediments and ground rocks, are first homogenized and dispersed by a hand-held ultrasonicator in an incubation buffer. They are then filtered (5 - 20 μm) to remove the coarse material, and the filtrate is incubated with Abs. Immunoreactions are revealed by a final incubation with a mixture of the 17 fluorescence-labeled Abs and are read by a portable fluorescence detector. The whole process takes around 3 h, most of it corresponding to two 1-h periods of incubation. The output is an image, where bright spots correspond to the positive detection of cyanobacterial markers.

  20. Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

    Science.gov (United States)

    Wu, Junlin; Liu, Xiaoyun; Peng, Yunping

    2014-01-01

    A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Analysis of serotonin concentrations in human milk by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Chiba, Takeshi; Maeda, Tomoji; Tairabune, Tomohiko; Tomita, Takashi; Sanbe, Atsushi; Takeda, Rika; Kikuchi, Akihiko; Kudo, Kenzo

    2017-03-25

    Serotonin (5-hydroxytryptamine, 5-HT) plays an important role in milk volume homeostasis in the mammary gland during lactation; 5-HT in milk may also affect infant development. However, there are few reports on 5-HT concentrations in human breast milk. To address this issue, we developed a simple method based on high-performance liquid chromatography with fluorescence detection (HPLC-FD) for measuring 5-HT concentrations in human breast milk. Breast milk samples were provided by four healthy Japanese women. Calibration curves for 5-HT in each sample were prepared with the standard addition method between 5 and 1000 ng/ml, and all had correlation coefficients >0.999. The recovery of 5-HT was 96.1%-101.0%, with a coefficient of variation of 3.39%-8.62%. The range of 5-HT concentrations estimated from the calibration curves was 11.1-51.1 ng/ml. Thus, the HPLC-FD method described here can effectively extract 5-HT from human breast milk with high reproducibility. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Multi-colorimetric sensor array for detection of explosives in gas and liquid phase

    Science.gov (United States)

    Kostesha, N.; Alstrøm, T. S.; Johnsen, C.; Nielsen, K. A.; Jeppesen, J. O.; Larsen, J.; Boisen, A.; Jakobsen, M. H.

    2011-05-01

    In the framework of the research project "Xsense" at the Technical University of Denmark (DTU) we are developing a simple colorimetric sensor array which can be useful in detection of explosives like DNT, TATP, HMX, RDX and identification of reagents needed for making homemade explosives. The technology is based on an array of chemoselective compounds immobilized on a solid support. Upon exposure to the analyte in suspicion the colorimetric array changes color. Each chosen compound reacts chemo-selectively with analytes of interest. A change in a color signature indicates the presence of unknown explosives and volatile organic compounds (VOCs). We are working towards the selection of compounds that undergo color changes in the presence of explosives and VOCs, as well as the development of an immobilization method for the molecules. Digital imaging of the colorimetric array before and after exposure to the analytes creates a color difference map which gives a unique fingerprint for each explosive and VOCs. Such sensing technology can be used for screening relevant explosives in a complex background as well as to distinguish mixtures of volatile organic compounds distributed in gas and liquid phases. This sensor array is inexpensive, and can potentially be produced as single use disposable.

  3. Prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, V.; Chirac, T.; Lasserre, T., E-mail: vincent.fischer@cea.fr, E-mail: tchirac@gmail.fr, E-mail: thierry.lasserre@cea.fr [Commissariat a l' énergie atomique et aux énergies alternatives, Centre de Saclay, IRFU, 91191 Gif-sur-Yvette (France); and others

    2015-08-01

    Core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-MeV range. Several Large Liquid Scintillator-based Detectors (LLSD) are currently operated worldwide, being very effective for low energy antineutrino detection through the Inverse Beta Decay (IBD) process. In this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of IBD kinematics over the broad energy range of supernova neutrinos. Combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% C.L.). After the addition of the next generation of scintillator-based detectors, the accuracy could reach 12 degrees (68% C.L.), therefore reaching the performances of the large water Čerenkov neutrino detectors. We also discuss a possible improvement of the SuperNova Early Warning System (SNEWS) inter-experiment network with the implementation of a directionality information in each experiment. Finally, we discuss the possibility to constrain the neutrino energy spectrum as well as the mass of the newly born neutron star with the LLSD data.

  4. Insights in groundwater organic matter from Liquid Chromatography-Organic Carbon Detection

    Science.gov (United States)

    Rutlidge, H.; Oudone, P.; McDonough, L.; Andersen, M. S.; Baker, A.; Meredith, K.; O'Carroll, D. M.

    2017-12-01

    Understanding the processes that control the concentration and characteristics of organic matter in groundwater has important implications for the terrestrial global carbon budget. Liquid Chromatography - Organic Carbon Detection (LC-OCD) is a size-exclusion based chromatography technique that separates the organic carbon into molecular weight size fractions of biopolymers, humic substances, building blocks (degradation products of humic substances), low molecular weight acids and low molecular weight neutrals. Groundwater and surface water samples were collected from a range of locations in Australia representing different surface soil, land cover, recharge type and hydrological properties. At one site hyporheic zone samples were also collected from beneath a stream. The results showed a general decrease in the aromaticity and molecular weight indices going from surface water, hyporheic downwelling and groundwater samples. The aquifer substrate also affected the organic composition. For example, groundwater samples collected from a zone of fractured rock showed a relative decrease in the proportion of humic substances, suggestive of sorption or degradation of humic substances. This work demonstrates the potential for using LC-OCD in elucidating the processes that control the concentration and characteristics of organic matter in groundwater.

  5. Detector cell based on plastic liquid-core waveguides suitable for aqueous solutions: one-to-two decades improved detection limits in

    NARCIS (Netherlands)

    Gooijer, C.; de Beer, T.; Bader, A.N.; van Iperen, D.J.; Brinkman, U.A.T.; Hoornweg, G.Ph.

    1998-01-01

    A new type of detector cell is presented, which is designed to improve concentration detection limits in conventional-size reversed-phase column liquid chromatography (LC) with ultraviolet (UV)-visible absorption detection. It is based on a recently developed plastic liquid-core waveguide (LCW),

  6. Femtomolar detection of 2,4-dichlorophenoxyacetic acid herbicides via competitive immunoassays using microfluidic based carbon nanotube liquid gated transistor.

    Science.gov (United States)

    Wijaya, I Putu Mahendra; Nie, Tey Ju; Gandhi, Sonu; Boro, Robin; Palaniappan, Alagappan; Hau, Goh Wei; Rodriguez, Isabel; Suri, C Raman; Mhaisalkar, Subodh G

    2010-03-07

    Monitoring of environmental pollutants has become increasingly important due to concern over potential health and environmental impact inflicted by these chemicals. In this contribution, we focus on the development of an all-plastic biosensor comprising laminated single-walled carbon nanotubes as the active element and its conductance modulation in a liquid-gated field effect transistor, as the principle of transduction, for the detection of 2,4-dicholorophenoxy acetic acid (2,4-D) herbicide. The reported biosensor is capable of performing real-time label-free detection of analytes in liquid environment. This biosensor which relies on immunoassay principle for specificity is able to detect down to 500 fM levels of 2,4-D in soil samples.

  7. Determination of chemotherapeutic drugs in human urine by capillary electrophoresis with UV and fluorimetric detection using solid-supported liquid-liquid extraction for sample clean-up.

    Science.gov (United States)

    Hurtado-Sánchez, María del Carmen; Acedo-Valenzuela, María Isabel; Durán-Merás, Isabel; Rodríguez-Cáceres, María Isabel

    2015-06-01

    Capillary electrophoresis was used for the rapid determination of three chemotherapeutic drugs employed to treat colorectal cancer: irinotecan, tegafur, and leucovorin, and their main metabolites (7-ethyl-10-hydroxycamptothecin and 5-fluorouracil), in human urine samples. A phosphate buffer (pH 11.34; 20 mM) was selected as the background electrolyte. A hydrodynamic injection (9 s, 30 mbar) was applied and the separation was carried out using a separation temperature and voltage of 25°C and 25 kV, respectively. A capillary with two detection windows for serial online UV and fluorescence detection was satisfactorily employed. A solid-supported liquid-liquid extraction procedure was optimized for the clean-up of the urine samples and the extraction of the analytes. Matrix effects were assessed and signal suppression was observed for three of the analytes, thus, matrix-matched calibration was used for compensating residual matrix effects on these analytes. The proposed method allows the separation and quantification of the chemotherapeutics in less than 6 min. Detection limits range between 0.01 and 0.30 mg/L. The method was satisfactorily applied to the determination of the target compounds in human urine samples, with recoveries of 92.4-107.7%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. On-line detection of illicit substances in liquid phase with proton-transfer-reaction mass spectrometry (PTR-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Juerschik, Simone; Agarwal, Bishu; Petersson, Fredrik [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); Sulzer, Philipp; Haidacher, Stefan; Jordan, Alfons; Schottkowsky, Ralf; Hartungen, Eugen; Hanel, Gernot; Seehauser, Hans; Maerk, Lukas [IONICON Analytik GmbH, Eduard-Bodem-Gasse 3, 6020 Innsbruck (Austria); Maerk, Tilmann D. [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr. 25, 6020 Innsbruck (Austria); IONICON Analytik GmbH, Eduard-Bodem-Gasse 3, 6020 Innsbruck (Austria)

    2011-07-01

    The direct aqueous injection (DAI) technique was recently utilized for the detection of illicit substances in liquid phase. DAI turns out to be an ideal solution for direct analysis of liquid samples, since we can make good use of the outstanding advantages, such as real-time analysis, no sample preparation, low detection limits and short response time. Differences in TNT concentration in the water could be seen dependent on time and original size of the pieces and we could demonstrate a linear correlation between the concentration in liquid and the PTR-MS signal. Furthermore, we were also able to demonstrate that this method is capable of detecting minute traces of ''rape drugs'', i.e. {gamma}-butyrolactone and 1,4-butanediol, in liquids. This new method achieving sensitivities in the around 100 pptw range appears therefore well suited for the fight against drug crime and terrorism and for the evaluation of contamination of ammunition dumping sites.

  9. Use of nonstatistical techniques for pattern recognition to detect risk groups among liquidators of the Chernobyl NPP accident aftereffects

    International Nuclear Information System (INIS)

    Blinov, N.N.; Guslistyj, V.P.; Misyurev, A.V.; Novitskaya, N.N.; Snigireva, G.P.

    1993-01-01

    Attempt of using of the nonstatistical techniques for pattern recognition to detect the risk groups among liquidators of the Chernobyl NPP accident aftereffects was described. 14 hematologic, biochemical and biophysical blood serum parameters of the group of liquidators of the Chernobyl NPP accident impact as well as the group of donors free of any radiation dose (controlled group) were taken as the diagnostic parameters. Modification of the nonstatistical techniques for pattern recognition based on the assessment calculations were used. The patients were divided into risk group at the truth ∼ 80%

  10. Determination of Bitter Orange alkaloids in dietary supplements standard reference materials by liquid chromatography with ultraviolet absorbance and fluorescence detection.

    Science.gov (United States)

    Putzbach, Karsten; Rimmer, Catherine A; Sharpless, Katherine E; Sander, Lane C

    2007-07-13

    Four adrenergic amines [synephrine, octopamine, tyramine, and n-methyltyramine] were determined in a variety of Bitter Orange containing dietary supplements. Two extraction techniques were evaluated in detail: Soxhlet extraction and sonication extraction. A liquid chromatographic separation using a reversed-phase C(18) stationary phase and the ion-pairing reagent sodium dodecyl sulfate was developed to separate the Bitter Orange alkaloids. Ultraviolet absorbance detection at 220 nm and fluorescence detection with excitation at 273 nm and emission at 304 nm were used for the alkaloid detection. The method described was used for the assignment of the levels of the predominant alkaloids in three candidate standard reference materials containing Bitter Orange.

  11. Rapid on-site/in-situ detection of heavy metal ions in environmental water using a structure-switching DNA optical biosensor

    Science.gov (United States)

    Long, Feng; Zhu, Anna; Shi, Hanchang; Wang, Hongchen; Liu, Jingquan

    2013-07-01

    A structure-switching DNA optical biosensor for rapid on-site/in situ detection of heavy metal ions is reported. Mercury ions (Hg2+), highly toxic and ubiquitous pollutants, were selected as model target. In this system, fluorescence-labeled DNA containing T-T mismatch structure was introduced to bind with DNA probes immobilized onto the sensor surface. In the presence of Hg2+, some of the fluorescence-labeled DNAs bind with Hg2+ to form T-Hg2+-T complexes through the folding of themselves into a hairpin structure and dehybridization from the sensor surface, which leads to decrease in fluorescence signal. The total analysis time for a single sample was less than 10 min with detection limit of 1.2 nM. The rapid on-site/in situ determination of Hg2+ was readily performed in natural water. This sensing strategy can be extended in principle to other metal ions by substituting the T-Hg2+-T complexes with other specificity structures that selectively bind to other analytes.

  12. Analysis of alkyl phosphates in petroleum samples by comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection and post-column Deans switching.

    Science.gov (United States)

    Nizio, Katie D; Harynuk, James J

    2012-08-24

    Alkyl phosphate based gellants used as viscosity builders for fracturing fluids used in the process of hydraulic fracturing have been implicated in numerous refinery-fouling incidents in North America. In response, industry developed an inductively coupled plasma optical emission spectroscopy (ICP-OES) based method for the analysis of total volatile phosphorus in distillate fractions of crude oil; however, this method is plagued by poor precision and a high limit of detection (0.5±1μg phosphorus mL(-1)). Furthermore this method cannot provide speciation information, which is critical for developing an understanding of the challenge of alkyl phosphates at a molecular level. An approach using comprehensive two-dimensional gas chromatography with nitrogen phosphorus detection (GC×GC-NPD) and post-column Deans switching is presented. This method provides qualitative and quantitative profiles of alkyl phosphates in industrial petroleum samples with increased precision and at levels comparable to or below those achievable by ICP-OES. A recovery study in a fracturing fluid sample and a profiling study of alkyl phosphates in four recovered fracturing fluid/crude oil mixtures (flowback) are also presented. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. 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.

    Science.gov (United States)

    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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Using of acoustic technologies for detection of explosives in gas, liquid and solid medium

    International Nuclear Information System (INIS)

    Valyaev, A. N.; Yanushkevich, V.A.

    2004-01-01

    Full text: Some industrial nuclear power objects are very attractive for the realization of radiological and chemical terrorism acts with using of explosives. Although up today this type of terrorism is not revealed itself, but the problem of detection of explosives at these objects is becoming very actual one, for example, in connection with the implementation of the urgent decommissioning of nuclear powered vessels. Such decommissioning includes the utilization the dangerous radioactive and chemical elements, contained in submarines and vessels. This actual problem is existed not only in Russia, but also in abroad. It is noticed that catastrophes at these objects will have in addition the great negative mental effect on population of all over the world, as it was after the Chernobyl accident. The using of the modern nuclear physics methods for detection and analysis of explosives is connected with the following difficulties: (1) we have to have the unique and the expensive equipment; (2) the special preparation of sample probes; (3) a long time is often necessary for analysis; (4) the high qualification of service personal is needed. We proposed to use for these purposes the complex of acoustic techniques, that are based on the high sensitivity of acoustic characteristics of any matter to their physical and chemical properties.Any acoustic signal has the following main parameters: (1) frequency (ω); (2) amplitude of pressure (ρ); (3) wave and amplitude bands; (4) velocity of acoustic wave propagation (sound velocity) (C); (5) space and temporal signal evolution, that is determined by the values of coefficients of temporal attenuation (α), space adsorption (β) and sound dispersion on obstacles and impurities. Our acoustic analysis is included the determination of C, α and β values for solid and liquid explosives. The exact measurements of these parameters and their dependences from frequency and temperature are conducted in the special acoustic cells, that

  15. Development of a novel infrared-based visualization technique to detect liquid-gas phase dynamics on boiling surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Dae [Kyunghee University, Yongin (Korea, Republic of)

    2011-05-15

    modeling of all these two-phase heat transfer phenomena, there is clearly a need to detect the liquid-vapor-solid triple contact line and measure its physical characteristics (extension, speed, temperature). In this paper we demonstrate the application to boiling heat transfer of a recently-developed experimental technique, named DEPIcT

  16. Calculation of risk-based detection limits for radionuclides in the liquid effluents from Korean nuclear power plants

    International Nuclear Information System (INIS)

    Cheong, Jae Hak

    2017-01-01

    In order to review if present detection limits of radionuclides in liquid effluent from nuclear power plants are effective enough to warrant compliance with regulatory discharge limits, a risk-based approach is developed to derive a new detection limit for each radionuclide based on radiological criteria. Equations and adjustment factors are also proposed to discriminate the validity of the detection limits for multiple radionuclides in the liquid effluent with or without consideration of the nuclide composition. From case studies to three nuclear power plants in Korea with actual operation data from 2006 to 2015, the present detection limits have turned out to be effective for Hanul Unit 1 but may not be sensitive enough for Kori Unit 1 (8 out of 14 radionuclides) and Wolsong Unit 1 (9 out of 42 radionuclides). However, it is shown that the present detection limits for the latter two nuclear power plants can be justified, if credit is given to the radionuclide composition. Otherwise, consideration should be given to adjustment of the present detection limits. The risk-based approach of this study can be used to determine the validity of established detection limits of a specific nuclear power plant. (author)

  17. Identification and quantification of flavonoids in human urine samples by column switching liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, S. E.; Freese, R.; Cornett, Claus

    2000-01-01

    A rapid and sensitive high-performance liquid chromatographic mass spectrometric (HPLC-MS) method is described for the determination and quantification of 12 dietary flavonoid glycosides and aglycons in human urine samples. Chromatographic separation of the analytes of interest was achieved by co...

  18. Switching terahertz wave with grating-coupled Kretschmann configuration.

    Science.gov (United States)

    Jiu-Sheng, Li

    2017-08-07

    We present a terahertz wave switch utilizing Kretschmann configuration which consists of high-refractive-index prism-liquid crystal-periodically grooved metal grating. The switching mechanism of the terahertz switch is based on spoof surface plasmon polariton (SSPP) excitation in the attenuated total reflection regime by changing the liquid crystal refractive index. The results highlighted the fact that the feasibility to "tune" the attenuated total reflection terahertz wave intensity by using the external applied bias voltage. The extinction ratio of the terahertz switch reaches 31.48dB. The terahertz switch has good control ability and flexibility, and can be used in potential terahertz free space device systems.

  19. Ionic-liquid-based dispersive liquid-liquid microextraction combined with magnetic solid-phase extraction for the determination of aflatoxins B1, B2, G1, and G2in animal feeds by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Zhao, Jiao; Zhu, Yan; Jiao, Yang; Ning, Jinyan; Yang, Yaling

    2016-10-01

    A novel two-step extraction technique combining ionic-liquid-based dispersive liquid-liquid microextraction with magnetic solid-phase extraction was developed for the preconcentration and separation of aflatoxins in animal feedstuffs before high-performance liquid chromatography coupled with fluorescence detection. In this work, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate was used as the extractant in dispersive liquid-liquid microextraction, and hydrophobic pelargonic acid modified Fe 3 O 4 magnetic nanoparticles as an efficient adsorbent were applied to retrieve the aflatoxins-containing ionic liquid. Notably, the target of magnetic nanoparticles was the ionic liquid rather than the aflatoxins. Because of the rapid mass transfer associated with the dispersive liquid-liquid microextraction and magnetic solid phase steps, fast extraction could be achieved. The main parameters affecting the extraction recoveries of aflatoxins were investigated and optimized. Under the optimum conditions, vortexing at 2500 rpm for 1 min in the dispersive liquid-liquid microextraction and magnetic solid-phase extraction and then desorption by sonication for 2 min with acetonitrile as eluent. The recoveries were 90.3-103.7% with relative standard deviations of 3.2-6.4%. Good linearity was observed with correlation coefficients ranged from 0.9986 to 0.9995. The detection limits were 0.632, 0.087, 0.422 and 0.146 ng/mL for aflatoxins B 1 , B2, G1, and G2, respectively. The results were also compared with the pretreatment method carried out by conventional immunoaffinity columns. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Determination of triazole pesticide residues in edible oils using air-assisted liquid-liquid microextraction followed by gas chromatography with flame ionization detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Feriduni, Behruz; Mogaddam, Mohammad Reza Afshar

    2015-03-01

    In the present study, a rapid, simple, and highly efficient sample preparation method based on air-assisted liquid-liquid microextraction followed by gas chromatography with flame ionization detection was developed for the extraction, preconcentration, and determination of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, and triticonazole) in edible oils. Initially, the oil samples were diluted with hexane and a few microliter of a less soluble organic solvent (extraction solvent) in hexane was added. To form fine and dispersed extraction solvent droplets, the mixture of oil sample solution and extraction solvent is repeatedly aspirated and dispersed with a syringe. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 2.2-6.1 and 7.3-20 μg/L, respectively. Enrichment factors and extraction recoveries were in the ranges of 71-96 and 71-96%, respectively. The relative standard deviations for the extraction of 100 and 250 μg/L of each pesticide were less than 5% for intraday (n = 6) and interday (n = 3) precisions. Finally edible oil samples were successfully analyzed using the proposed method, and hexaconazole was found in grape seed oil. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Determination of ascorbic acid and carotenoids in food commodities by liquid chromatography with mass spectrometry detection.

    Science.gov (United States)

    Frenich, A Garrido; Torres, M E Hernández; Vega, A Belmonte; Vidal, J L Martínez; Bolaños, P Plaza

    2005-09-21

    Two methods, one to determine ascorbic acid and one to determine lycopene and beta-carotene, in vegetables and fruits by liquid chromatography coupled with mass spectrometry (LC-MS) have been established. The chromatographic separation of the studied compounds and their MS parameters were optimized to improve selectivity and sensitivity. In both methods, separation was carried out with two coupled columns, first a C(18) and then a dC(18), using as mobile phase 70% methanol (0.005% acetic acid) and 30% acetic acid 0.05% for ascorbic acid determination and a mixture of methanol, tetrahydrofuran, and acetonitrile (60:30:10 v/v/v) for carotenoid analysis in isocratic mode. The molecular ion was selected for the quantification in selective ion monitoring (SIM) mode. Ascorbic acid was detected with electrospray ionization probe (ESI) in negative mode, while chemical ionization atmospheric pressure (APCI) in positive mode was used for the target carotenoids. The methodology for ascorbic acid analysis is based on an extraction with polytron using methanol and a mixture of methaphosphoric acid and acetic acid. Extraction of the carotenoids was carried out with tetrahydrofuran/methanol (1:1) (v/v). The proposed methods were applied, after their corresponding validations, to the analysis of four varieties of tomatoes, tomato in tin enriched and dried tomato, and to the analysis of mango and kiwi fruits, to compare the content in these compounds. Moreover, the influence of the process of freezing and the effect that the manipulation/preservation has in the content of ascorbic acid in tomato have also been studied.

  2. Determination of Betaine in Fructus Lycii Using Hydrophilic Interaction Liquid Chromatography with Evaporative Light Scattering Detection

    International Nuclear Information System (INIS)

    Shin, Hyun Du; Suh, Joon Hyuk; Kim, Jung Hyun; Lee, Hye Yeon; Eom, Han Young; Kim, Un Yong; Yang, Dong Hyug; Han, Sang Beom; Youm, Jeong Rok

    2012-01-01

    A simple new method was developed for the determination of betaine in Fructus Lycii using hydrophilic interaction liquid chromatography with evaporative light scattering detection (HILIC-ELSD). Good chromatographic separation and reasonable betaine retention was achieved on a Kinetex HILIC column (2.1 x 100 mm, 2.6 μm) packed with fused-core particle. The mobile phase consisted of (A) acetonitrile and (B) 10 mM ammonium formate (pH 3.0)/acetonitrile (90/10, v/v). It was used with gradient elution at a flow rate of 0.7 mL/ min. The column temperature was set at 27.5 .deg. C and the injection volume was 10 μL. The ELSD drift tube temperature was 50 .deg. C and the nebulizing gas (nitrogen) pressure was 3.0 bar. Stachydrine, a zwitterionic compound, was used as an internal standard. Calibration curve over 10-250 μg/mL showed good linearity (R 2 > 0.9992) and betaine in the 70% methanol extract of Fructus Lycii was well separated from other peaks. Intra and inter-day precision ranged from 1.1 to 3.0% and from 2.4 to 5.3%, respectively, while intra- and inter-day accuracy ranged from 100.0 to 107.0% and from 94.3 to 103.9%, respectively. The limit of quantification (LOQ) was 10 μg/mL and the recoveries were in the range of 98.2-102.7%. The developed HILIC-ELSD method was successfully applied to quantitatively determine the amount of betaine in fourteen Fructus Lycii samples from different locations, demonstrating that this method is simple, rapid, and suitable for the quality control of Fructus Lycii

  3. A survey of existing and emerging technologies for external detection of liquid leaks at the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, R.E.; Teel, S.S.

    1994-10-01

    During the history of the Hanford Site, many structures were built that stored and transported liquids used for the production mission; some of these structures are still active. Active structures include underground storage tanks retention basins, and pipes and pipelines. Many of the liquids stored and transported in these structures are potentially hazardous to human health and the environment. Any leakage of liquids from active structures, has the added potential to mobilize contaminants in the unsaturated zone. Therefore, it is beneficial to monitor these structures for leaks. The purpose of tills report is to catalog existing and emerging technologies that have potential for the external monitoring of liquid leaks. The report will focus primarily on the needs at the Hanford Site tank farms that are located in the 200 Areas, but will also be relevant to other Hanford Site facilities. Leak detection systems, both external and internal, are currently used at some Hanford facilities. This report focuses on the detection of leaks as they migrate into the soils surrounding the facilities.

  4. A survey of existing and emerging technologies for external detection of liquid leaks at the Hanford Site

    International Nuclear Information System (INIS)

    Lewis, R.E.; Teel, S.S.

    1994-10-01

    During the history of the Hanford Site, many structures were built that stored and transported liquids used for the production mission; some of these structures are still active. Active structures include underground storage tanks retention basins, and pipes and pipelines. Many of the liquids stored and transported in these structures are potentially hazardous to human health and the environment. Any leakage of liquids from active structures, has the added potential to mobilize contaminants in the unsaturated zone. Therefore, it is beneficial to monitor these structures for leaks. The purpose of tills report is to catalog existing and emerging technologies that have potential for the external monitoring of liquid leaks. The report will focus primarily on the needs at the Hanford Site tank farms that are located in the 200 Areas, but will also be relevant to other Hanford Site facilities. Leak detection systems, both external and internal, are currently used at some Hanford facilities. This report focuses on the detection of leaks as they migrate into the soils surrounding the facilities

  5. Low-level detection and quantification of Plutonium(III, IV, V,and VI) using a liquid core waveguide

    International Nuclear Information System (INIS)

    Wilson, Richard E.; Hu, Yung-Jin; Nitsche, Heino

    2003-01-01

    Understanding the aqueous chemistry of plutonium, in particular in environmental conditions, is often complicated by plutonium's complex redox chemistry. Because plutonium possesses four oxidation states, all of which can coexist in solution, a reliable method for the identification of these oxidation states is needed. The identification of plutonium oxidation states at low levels in aqueous solution is often accomplished through an indirect determination using series of liquid-liquid extraction procedures using oxidation state specific reagents such as HDEHP and TTA. While these methods, coupled with radioactive counting techniques provide superior limits of detection they may influence the plutonium redox equilibrium, are time consuming, waste intensive and costly. Other analytical methods such as mass spectrometry and radioactive counting as stand alone methods provide excellent detection limits but lack the ability to discriminate between the oxidation states of the plutonium ions in solution

  6. Small-molecule fluorophores to detect cell-state switching in the context of high-throughput screening.

    Science.gov (United States)

    Wagner, Bridget K; Carrinski, Hyman A; Ahn, Young-Hoon; Kim, Yun Kyung; Gilbert, Tamara J; Fomina, Dina A; Schreiber, Stuart L; Chang, Young-Tae; Clemons, Paul A

    2008-04-02

    A small molecule capable of distinguishing the distinct states resulting from cellular differentiation would be of enormous value, for example, in efforts aimed at regenerative medicine. We screened a collection of fluorescent small molecules for the ability to distinguish the differentiated state of a mouse skeletal muscle cell line. High-throughput fluorescence-based screening of C2C12 myoblasts and myotubes resulted in the identification of six compounds with the desired selectivity, which was confirmed by high-content screening in the same cell states. The compound that resulted in the greatest fluorescence intensity difference between the cell states was used as the screening agent in a pilot screen of 84 kinase inhibitors, each present in four doses, for inhibition of myogenesis. Of the kinase inhibitors, 17 resulted in reduction of fluorescence at one or more concentrations; among the "hits" included known inhibitors of myogenesis, confirming that this compound is capable of detecting the differentiated myotube state. We suggest that the strategy of screening for screening agents reported here may be extended more broadly in the future.

  7. Determination of Polycyclic Aromatic Hydrocarbons in Automobile Exhaust by Means of High-Performance Liquid Chromatography with Fluorescence Detection

    DEFF Research Database (Denmark)

    Nielsen, Tom

    1979-01-01

    A chromatographic method has been developed and applied to the determination of polycyclic aromatic hydrocarbons (PAHs) in particulate matter in automobile exhaust, in petrols, and in crankcase oils. The PAHs were purified from other organic compounds by thin-layer chromatography, separated by high......-performance liquid chromatography, and measured by means of on-line fluorescence detection. The identities of the PAHs were verified by comparing the emission spectra obtained by a stop-flow technique with those of standard PAHs...

  8. A Study of Nuclear Recoils in Liquid Argon Time Projection Chamber for the Direct Detection of WIMP Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huajie [Princeton Univ., NJ (United States)

    2014-11-01

    Robust results of WIMP direct detection experiments depend on rm understandings of nuclear recoils in the detector media. This thesis documents the most comprehensive study to date on nuclear recoils in liquid argon - a strong candidate for the next generation multi-ton scale WIMP detectors. This study investigates both the energy partition from nuclear recoil energy to secondary modes (scintillation and ionization) and the pulse shape characteristics of scintillation from nuclear recoils.

  9. Position detection and observation of a conducting filament hidden under a top electrode in a Ta₂O₅-based atomic switch.

    Science.gov (United States)

    Nayak, Alpana; Wang, Qi; Itoh, Yaomi; Tsuruoka, Tohru; Hasegawa, Tsuyoshi; Boodhoo, Liam; Mizuta, Hiroshi; Aono, Masakazu

    2015-04-10

    Resistive random access memories (ReRAMs) are promising next-generation memory devices. Observation of the conductive filaments formed in ReRAMs is essential in understanding their operating mechanisms and their expected ultimate performance. Finding the position of the conductive filament is the key process in the preparation of samples for cross-sectional transmission electron microscopy (TEM) imaging. Here, we propose a method for locating the position of conductive filaments hidden under top electrodes. Atomic force microscopy imaging with a conductive tip detects the current flowing through a conductive filament from the bottom electrode, which reaches its maximum at a position that is above the conductive filament. This is achieved by properly biasing a top electrode, a bottom electrode and the conductive tip. This technique was applied to Cu/Ta2O5/Pt atomic switches, revealing the formation of a single Cu filament in a device, although the device had a large area of 5 × 5 μm(2). Change in filament size was clearly observed depending on the compliance current used in the set process. It was also found from the TEM observation that the cross-sectional shape of the formed filament varies considerably, which is attributable to different Cu nuclei growth mechanisms.

  10. Gold nanoclusters as switch-off fluorescent probe for detection of uric acid based on the inner filter effect of hydrogen peroxide-mediated enlargement of gold nanoparticles.

    Science.gov (United States)

    Liu, Yanyan; Li, Hongchang; Guo, Bin; Wei, Lijuan; Chen, Bo; Zhang, Youyu

    2017-05-15

    Herein we report a novel switch-off fluorescent probe for highly selective determination of uric acid (UA) based on the inner filter effect (IFE), by using poly-(vinylpyrrolidone)-protected gold nanoparticles (PVP-AuNPs) and chondroitin sulfate-stabilized gold nanoclusters (CS-AuNCs) as the IFE absorber/fluorophore pair. In this IFE-based fluorometric assay, the newly designed CS-AuNCs were explored as an original fluorophore and the hydrogen peroxide (H 2 O 2 ) -driven formed PVP-AuNPs can be a powerful absorber to influence the excitation of the fluorophore, due to the complementary overlap between the absorption band of PVP-AuNPs and the emission band of CS-AuNCs. Under the optimized conditions, the extent of the signal quenching depends linearly on the H 2 O 2 concentration in the range of 1-100μM (R 2 =0.995) with a detection limit down to 0.3μM. Based on the H 2 O 2 -dependent fluorescence IFE principle, we further developed a new assay strategy to enable selective sensing of UA by using a specific uricase-catalyzed UA oxidation as the in situ H 2 O 2 generator. The proposed uricase-linked IFE-based assay exhibited excellent analytical performance for measuring UA over the concentration ranging from 5 to 100μM (R 2 =0.991), and can be successfully applied to detection of UA as low as 1.7μM (3σ) in diluted human serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Quantitative Determination of Hydrocarbon Group-Types via High Performance Liquid Chromatography with Dielectric Constant Detection.

    Science.gov (United States)

    1985-07-01

    lower grade crudes -. and off-streams as well as processed liquids from alternate sources of energy, e.g., shale oil, tar sands, coal liquids, and biomass...Fuel No. 2 40 17 Comparative Analysis of Tar Sands Distillate 41 18 Comparative Analysis of Xylene Bottoms 42 19 Comparative Analysis of 2040 Solvent...factors are used to analyze hydrotreated and hydrocracked materials having the same boiling range. As Drushel (Reference 5) observed, given e1 % : 4 * % . 4

  12. Electrochemical structure-switching sensing using nanoplasmonic devices

    Energy Technology Data Exchange (ETDEWEB)

    Patskovsky, Sergiy; Dallaire, Anne-Marie; Blanchard-Dionne, Andre-Pierre; Meunier, Michel [Department of Engineering Physics, Laser Processing and Plasmonics Laboratory, Polytechnique, Montreal, Station Centre-ville, QC (Canada); Vallee-Belisle, Alexis [Laboratory of Biosensors and Nanomachines, Departement de Chimie, Universite de Montreal, QC (Canada)

    2015-12-15

    In this article, the implementation of electrochemical plasmonic nanostructures functionalized with DNA-based structure-switching sensors is presented. eNanoSPR devices with open and microfluidic measurement cells are developed on the base of nanohole arrays in 100 nm gold film and applied for combined microscopic and electrochemical surface plasmon (eSPR) visualization. eSPR voltammograms and spectroscopy are performed using planar three electrode schematic with plasmonic nanostructure operated as working electrode. Limit of detection of eNanoSPR devices for oligonucleotide hybridization is estimated in the low nanomolar and applications for structure-switching electro-plasmonic sensing in complex liquids are discussed. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Sensitive determination of specific radioactivity of positron emission tomography radiopharmaceuticals by radio high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Nakao, Ryuji; Furutsuka, Kenji; Yamaguchi, Masatoshi; Suzuki, Kazutoshi

    2008-10-01

    A sensitive quality control method is often required in positron emission tomography (PET) radiopharmaceutical analysis due to the high specific radioactivity of synthetic products. The applicability of a radio high-performance liquid chromatography (HPLC) method with fluorescence detection was evaluated for a wide variety of PET radiopharmaceuticals. In 29 different radiopharmaceuticals studied, 20 compounds exhibited native fluorescence. These properties enabled sensitive determination of their chemical masses by direct fluorimetric detection after separation by HPLC. For some substances, detection limits were below nanograms per milliliter level, at least 40 times better than current UV absorbance detection. Sufficient reproducibility and linearity were obtained for the analysis of pharmaceutical fluid. Post-column fluorimetric derivatization was also established for the quantitative determination of FDG and ClDG in [(18)F]FDG samples. These methods could be applied successfully to the analysis of PET radiopharmaceuticals with ultra-high specific radioactivity.

  14. Tyrosine-Based Ionic Liquid Crystals: Switching from a Smectic A to a Columnar Mesophase by Exchange of the Spherical Counterion.

    Science.gov (United States)

    Neidhardt, Manuel M; Wolfrum, Manpreet; Beardsworth, Stuart; Wöhrle, Tobias; Frey, Wolfgang; Baro, Angelika; Stubenrauch, Cosima; Giesselmann, Frank; Laschat, Sabine

    2016-11-07

    Synthetic strategies were developed to prepare l-tyrosine-based ionic liquid crystals with structural variations at the carboxylic and phenolic OH groups as well as the amino functionality. Salt metathesis additionally led to counterion variation. The liquid-crystalline properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS, SAXS). The symmetrical ILC chlorides bearing the same alkyl chain at both the ester and ether but either an acyclic or cyclic guanidinium group displayed enantiotropic SmA 2 mesophases with phase widths of 31-88 K irrespective of the head group. It was particularly the replacement of chloride in the acyclic guanidinium ILC by hexafluorophosphate that induced a phase change from SmA 2 to Col r . This phase change was attributed to a higher curvature of the interface due to the larger anion, which increased the effective head group cross-sectional area of the amphiphilic ILC. The unsymmetrical acyclic guanidinium chlorides, bearing a constant C 14 ester and variable alkyl chains on the phenolic position, formed enantiotropic SmA 2 phases. The derivative with the largest difference in chain lengths, however, displayed a Col r phase, resulting from discoid aggregates of the cone-shaped guanidinium chloride. The results are discussed in terms of the packing parameters, which indicate that the phase behaviour of the thermotropic tyrosine-based ILCs shows analogies to those of lyotropic liquid crystals. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Fluorescent switch for fast and selective detection of mercury (II) ions in vitro and in living cells and a simple device for its removal.

    Science.gov (United States)

    Yuan, Yue; Jiang, Shenlong; Miao, Qingqing; Zhang, Jia; Wang, Mengjing; An, Linna; Cao, Qinjingwen; Guan, Yafeng; Zhang, Qun; Liang, Gaolin

    2014-07-01

    A water-soluble, biocompatible, and fluorescent chemosensor (1) for label-free, simple, and fast detection of mercury ions (Hg(2+)) in aqueous solutions and in HepG2 cells with high selectivity is reported herein. Chelation of 1 with Hg(2+) results in the disappearance of its fluorescence emission at 350 nm and the appearance of a new emission at 405 nm. Selectivity and interference studies indicated that 1 could be selectively chelated by Hg(2+) without interference from other metal ions. Insight into the mechanisms responsible for its fluorescence effect was gained from ultrafast transient absorption spectroscopy. With these properties, 1 was successfully applied for imaging Hg(2+) in living cells and for removing Hg(2+) from river water. Moreover, we also constructed a simple device for fast and effective removal of Hg(2+) from contaminated liquid samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. A simple and sensitive HPLC method for analysis of imipramine in human plasma with UV detection and liquid-liquid extraction: Application in bioequivalence studies.

    Science.gov (United States)

    Rezazadeh, Mahboubeh; Emami, Jaber

    2016-01-01

    High-performance liquid chromatography (HPLC) methods employing ultraviolet (UV) detector are not sufficiently sensitive to measure the low plasma concentrations following single oral dose of imipramine. Therefore, in the present study a simple, rapid and yet sensitive HPLC method with UV detection was developed and validated for quantitation of imipramine in human plasma samples. An efficient liquid-liquid extraction (LLE) of imipramine from plasma with the mixture of hexane/isoamyl alcohol (98:2) and back extraction of the drug in acidic medium concomitant with evaporation of organic phase allowed the use of UV detector to conveniently measure plasma levels of this compound as low level as 3 ng/ml. Separation was achieved on a μ-Bondapak C18 HPLC column using sodium hydrogen phosphate solution (0.01 M)/acetonitrile (60/40 v/v) at pH 3.5 ± 0.1 at 1.5 ml/min. Trimipramine was used as the internal standard for analysis of plasma samples. The retention times for imipramine and trimipramine were 4.3 and 5.2 min, respectively. Calibration curve was linear in the range of 3-40 ng/ml using human plasma with the average extraction recovery of 85 ± 5%. Imipramine was found to be stable in plasma samples with no evidence of degradation during three freeze-thaw cycles and three months storage at -70°C. The current validated method was finally applied in bioequivalence studies of two different imipramine products according to a standard two-way crossover design with a two weeks washout period.

  17. Dispersive liquid-liquid microextraction coupled with digital image colorimetric analysis for detection of total iron in water and food samples.

    Science.gov (United States)

    Peng, Bo; Chen, Guorong; Li, Kai; Zhou, Min; Zhang, Ji; Zhao, Shengguo

    2017-09-01

    A simple and low cost assay for total iron in various samples based on dispersive liquid-liquid microextraction (DLLME) coupled with digital scanning image analysis was proposed. Orthogonal experiment design was utilized to optimize the amount of extraction solvent and disperser solvent, O-phenanthroline concentration and buffer pH. Under the optimum conditions, the calibration curve was linear over the range of 0.047-1.0μgmL -1 (R 2 >0.99) of iron. The limit of detection (LOD) for iron was 14.1μgL -1 and limit of quantification (LOQ) was 46.5μgL -1 . The relative standard deviations for seven replicate determinations of 0.5μgmL -1 of iron was 3.75%. The method was successfully applied for analysis of total iron in water and food samples without using any spectral instrument and it could have a potential industrial impact in developing fast and portable devices to analyze the iron content in water and certain foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Sensitive Detection of Organophosphorus Pesticides in Medicinal Plants Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with Sweeping Micellar Electrokinetic Chromatography.

    Science.gov (United States)

    Wei, Jin-Chao; Hu, Ji; Cao, Ji-Liang; Wan, Jian-Bo; He, Cheng-Wei; Hu, Yuan-Jia; Hu, Hao; Li, Peng

    2016-02-03

    A simple, rapid, and sensitive method using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) combined with sweeping micellar electrokinetic chromatography (sweeping-MEKC) has been developed for the determination of nine organophosphorus pesticides (chlorfenvinphos, parathion, quinalphos, fenitrothion, azinphos-ethyl, parathion-methyl, fensulfothion, methidathion, and paraoxon). The important parameters that affect the UA-DLLME and sweeping efficiency were investigated. Under the optimized conditions, the proposed method provided 779.0-6203.5-fold enrichment of the nine pesticides compared to the normal MEKC method. The limits of detection ranged from 0.002 to 0.008 mg kg(-1). The relative standard deviations of the peak area ranged from 1.2 to 6.5%, indicating the good repeatability of the method. Finally, the developed UA-DLLME-sweeping-MEKC method has been successfully applied to the analysis of the investigated pesticides in several medicinal plants, including Lycium chinense, Dioscorea opposite, Codonopsis pilosula, and Panax ginseng, indicating that this method is suitable for the determination of trace pesticide residues in real samples with complex matrices.

  19. Fiber Optic Coupled Raman Based Detection of Hazardous Liquids Concealed in Commercial Products

    Directory of Open Access Journals (Sweden)

    Michael L. Ramírez-Cedeño

    2012-01-01

    Full Text Available Raman spectroscopy has been widely proposed as a technique to nondestructively and noninvasively interrogate the contents of glass and plastic bottles. In this work, Raman spectroscopy is used in a concealed threat scenario where hazardous liquids have been intentionally mixed with common consumer products to mask its appearance or spectra. The hazardous liquids under consideration included the chemical warfare agent (CWA simulant triethyl phosphate (TEP, hydrogen peroxide, and acetone as representative of toxic industrial compounds (TICs. Fiber optic coupled Raman spectroscopy (FOCRS and partial least squares (PLS algorithm analysis were used to quantify hydrogen peroxide in whiskey, acetone in perfume, and TEP in colored beverages. Spectral data was used to evaluate if the hazardous liquids can be successfully concealed in consumer products. Results demonstrated that FOC-RS systems were able to discriminate between nonhazardous consumer products and mixtures with hazardous materials at concentrations lower than 5%.

  20. Training-induced improvement of response selection and error detection in aging assessed by task switching: Effects of cognitive, physical and relaxation training

    Directory of Open Access Journals (Sweden)

    Patrick Darius Gajewski

    2012-05-01

    Full Text Available Cognitive control functions decline with increasing age. One of them is response selection that forms the link between the goals and the motor system and is therefore crucial for performance outcomes in cognitive tasks. The present study examines if different types of group-based and trainer-guided training effectively enhance performance of older adults in a task switching task, and how this expected enhancement is reflected in electrophysiological brain activity, as measured in event-related potentials (ERPs. 141 healthy participants aged 65 years and older were randomly assigned to one of four groups: physical training (combined aerobic and strength-training, cognitive training (paper-pencil and computer-aided, relaxation and wellness (social control group and a no-contact control group that did not receive any intervention. Training sessions took place twice a week for 90 minutes for a period of 4 months.The results showed a greater improvement of performance for attendants of the cognitive training group compared to the other groups. This improvement was evident in a reduction of mixing costs in accuracy and intraindividual variability of speed, indexing improved maintenance of multiple task-sets in working memory and an enhanced coherence of neuronal processing. These findings were supported by event-related brain potentials (ERP which showed higher amplitudes in a number of potentials associated with response selection (N2, allocation of cognitive resources (P3b and error detection (Ne.Taken together, our findings suggest neurocognitive plasticity of aging brains which can be stimulated by broad and multilayered cognitive training and assessed in detail by electrophysiological methods.

  1. Simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography-tandem mass spectrometry with positive/negative ion-switching electrospray ionization and its application in pharmacokinetic study.

    Science.gov (United States)

    Ni, Yang; Zhou, Ying; Xu, Mingzhen; He, Xiaomeng; Li, Huqun; Haseeb, Satter; Chen, Hui; Li, Weiyong

    2015-03-25

    A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile-20mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m/z 150.0/91.0 for phentermine, m/z 452.1/344.3 for doxazosin, and negative m/z 338.3/77.9 for topiramate, m/z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1-800 ng mL(-1) for phentermine, 1-1000 ng mL(-1) for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of <15% at all concentrations. Blood samples were collected into heparinized tubes before and after administration. The simple and robust LC/MS/MS method was successfully applied for the simultaneous determination of phentermine and topiramate in a pharmacokinetic study in healthy male Chinese volunteers. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Miniaturized cavity ring-down detection in a liquid flow cell

    NARCIS (Netherlands)

    Bahnev, B.; van der Sneppen, L.; Wiskerke, A.E.; Ariese, F.; Gooijer, C.; Ubachs, W.M.G.

    2005-01-01

    A novel method for applying cavity ring-down spectroscopy in the liquid phase, compatible with LC analyses, is presented. The core of the setup is a home-built cavity ring-down flow cell (cell volume 12 μL) that is constructed using a silicon rubber spacer, which is clamped leak-tight between two

  3. Determination of Polychlorinated Biphenyls in Soil and Sediment by Selective Pressurized Liquid Extraction with Immunochemical Detection

    Science.gov (United States)

    A selective liquid pressurized extraction (SPLE) method was developed as a streamlined sample preparation/cleanup procedure for determining Aroclors and coplanar polychlorinated biphenyls (PCBs) in soil and sediment matrices. The SPLE method was coupled with an enzyme-linked imm...

  4. Improving Separation Performance and Detection Capabilities in Liquid Chromatography Using Active Flow Technology: A Review

    NARCIS (Netherlands)

    Camenzuli, M.; Shalliker, R.A.

    2015-01-01

    The development of sub-2-mu m particles, core shell particles, and monolithic columns has improved separation performance in liquid chromatography (LC) over the past 20 years. However, a key limitation that still prevents LC columns from reaching their full potential is the heterogeneity in the flow

  5. Urinary neopterin quantification by reverse-phase high-performance liquid chromatography with ultraviolet detection

    NARCIS (Netherlands)

    Castro, de M.R.; Marco, Di G.S.; Arita, D.Y.; Teixeira, L.C.; Pereira, A.B.; Casarini, D.E.

    2004-01-01

    Neopterin plays an important role in the malignant disease diagnostics. However, the methods employed in neopterin determination are generally difficult and/or time consuming. The aim of this work was to standardize a practical method to quantify neopterin using high-performance liquid

  6. Detection of Griseofulvin and Dechlorogriseofulvin by Thin-Layer Chromatography and Gas-Liquid Chromatography

    Science.gov (United States)

    Cole, R. J.; Kirksey, J. W.; Holaday, C. E.

    1970-01-01

    A rapid and accurate method is described for the determination of griseofulvin and dechlorogriseofulvin extracted from Penicillium urticae with chloroform. Thinlayer chromatography was used to tentatively identify griseofulvin or dechlorogriseofulvin, or both. Two gas-liquid chromatographic systems provided additional qualitative information and simultaneous quantitation of the individual compounds. PMID:5415206

  7. An on-line high performance liquid chromatography-crocin bleaching assay for detection of antioxidants

    NARCIS (Netherlands)

    Bountagkidou, O.; Klift, van der E.J.C.; Tsimidou, M.Z.; Ordoudi, S.A.; Beek, van T.A.

    2012-01-01

    An on-line HPLC (high performance liquid chromatography) method for the rapid screening of individual antioxidants in mixtures was developed using crocin as a substrate (i.e. oxidation probe) and 2,2'-azobis(2-amidinopropane dihydrochloride (AAPH)) in phosphate buffer (pH 7.5) as a radical

  8. Switched on!

    CERN Multimedia

    2008-01-01

    Like a star arriving on stage, impatiently followed by each member of CERN personnel and by millions of eyes around the world, the first beam of protons has circulated in the LHC. After years in the making and months of increasing anticipation, today the work of hundreds of people has borne fruit. WELL DONE to all! Successfully steered around the 27 kilometres of the world’s most powerful particle accelerator at 10:28 this morning, this first beam of protons circulating in the ring marks a key moment in the transition from over two decades of preparation to a new era of scientific discovery. "It’s a fantastic moment," said the LHC project leader Lyn Evans, "we can now look forward to a new era of understanding about the origins and evolution of the universe". Starting up a major new particle accelerator takes much more than flipping a switch. Thousands of individual elements have to work in harmony, timings have to be synchronize...

  9. Optimization of electrochemical detection in the high-performance liquid chromatography of lignin phenolics from lignocellulosic by-products.

    Science.gov (United States)

    Galletti, G C; Piccaglia, R; Concialini, V

    1990-05-16

    Free phenolic acids and aldehydes (p- and o-hydroxyphenylacetic acid, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillic acid, vanillin, syringic acid, p-coumaric acid, syringaldehyde and ferulic acid) were detected in wheat straw extracts by high-performance liquid chromatography with a dual-cell electrochemical detector operated in the redox mode. Phenolics were oxidized with coulometric efficiency in the first cell (+ 1.00 V), then detected by reduction in the second cell (-0.20 V). Compared with the oxidative mode, the reductive detection mode has the advantage of being unaffected by large amounts of interferents eluting at the front of the chromatogram that interfere with the detection of small and early eluting compounds. Hydrodynamic voltammograms in the oxidative, reductive and screen-out modes are presented and the corresponding detection limits for real sample are discussed. Perfect linearity of response was found in the range 5 x 10(-7) - 5 x 10(-5) M and detection limits were of the order of 50-500 fmol injected.

  10. Real time, Non-intrusive Detection of Liquid Nitrogen in Liquid Oxygen (LOX) at High Pressure and High Flow, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — SSC needs the sensors that are capable and can be operated in liquid oxygen (LOX) and or liquid hydrogen (LH2) cryogenic environment to improve SSC cryogenic...

  11. Determination of CYP4A11-catalyzed lauric acid 12-hydroxylation by high-performance liquid chromatography with radiometric detection.

    Science.gov (United States)

    Crespi, Charles L; Chang, Thomas K H; Waxman, David J

    2006-01-01

    Lauric acid serves as an endogenous substrate for the cytochrome P450 enzyme CYP4A11. A reverse-phase, high-performance liquid chromatography method is described for the quantification of 12-hydroxylauric acid formed enzymatically by incubation of 14C-labeled lauric acid with cDNA-expressed CYP4A11 or human liver microsomes. Analytical separation is achieved using a C18 column and a gradient of 30% acetonitrile and 2 mM perchloric acid to 100% methanol, using a detection scintillation counter. This method is applicable to enzymatic studies for determination of lauric acid 12-hydroxylation activity.

  12. LC-IMS-MS Feature Finder. Detecting Multidimensional Liquid Chromatography, Ion Mobility, and Mass Spectrometry Features in Complex Datasets

    Energy Technology Data Exchange (ETDEWEB)

    Crowell, Kevin L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Slysz, Gordon W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Baker, Erin Shammel [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lamarche, Brian L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Monroe, Matthew E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ibrahim, Yehia M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Payne, Samuel H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Gordon A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Richard D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-09-05

    We introduce a command line software application LC-IMS-MS Feature Finder that searches for molecular ion signatures in multidimensional liquid chromatography-ion mobility spectrometry-mass spectrometry (LC-IMS-MS) data by clustering deisotoped peaks with similar monoisotopic mass, charge state, LC elution time, and ion mobility drift time values. The software application includes an algorithm for detecting and quantifying co-eluting chemical species, including species that exist in multiple conformations that may have been separated in the IMS dimension.

  13. Determination of methyldibromoglutaronitrile in cosmetic products by high-performance liquid chromatography with electrochemical detection. Method validation

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Zachariae, Claus; Johansen, Jeanne D

    2004-01-01

    An increased frequency of contact allergy to methyldibromoglutaronitrile (MDBGN), a commonly used preservative in cosmetics and other consumer products, has been reported in recent years. A high-performance liquid chromatography (HPLC) method for the determination of MDBGN in cosmetic products has...... been validated in the present study. The identification is performed by reductive electrochemical detection of the bromine present in the molecule. The method is suitable for compliance testing of cosmetic products as well as for the research to support clinical and epidemiological studies....

  14. Rapid analysis of ethanol and water in commercial products using ionic liquid capillary gas chromatography with thermal conductivity detection and/or barrier discharge ionization detection.

    Science.gov (United States)

    Weatherly, Choyce A; Woods, Ross M; Armstrong, Daniel W

    2014-02-26

    Analysis of ethanol and water in consumer products is important in a variety of processes and often is mandated by regulating agencies. A method for the simultaneous quantitation of ethanol and water that is simple, accurate, precise, rapid, and cost-effective is demonstrated. This approach requires no internal standard for the quantitation of both ethanol and water at any/all levels in commercial products. Ionic liquid based gas chromatography (GC) capillary columns are used to obtain a fast analysis with high selectivity and resolution of water and ethanol. Typical run times are just over 3 min. Examination of the response range of water and ethanol with GC, thermal conductivity detection (TCD), and barrier ionization detection (BID) is performed. Quantitation of both ethanol and water in consumer products is accomplished with both TCD and BID GC detectors using a nonlinear calibration. Validation of method accuracy is accomplished by using standard reference materials.

  15. Determination of endogenous jasmonic acid in plant samples by liquid chromatography-electrochemical detection based on derivatization with dopamine.

    Science.gov (United States)

    Xie, Shanshan; Wang, Fang; Chen, Zilin

    2013-02-21

    Jasmonic acid (JA), a type of plant hormone, is widely distributed in a variety of higher plants at very low concentrations, usually several nanograms per gram (ng g(-1)) fresh weight of the plant tissue. The determination of endogenous JA is challenging work. The typical electrochemical oxidation behavior of JA could only be achieved under extreme conditions such as strongly acidic medium (H(2)SO(4)) and high applied working potential (1.4-1.6 V), which cannot be used in the electrochemical detection for liquid chromatography (LC). To realize electrochemical detection for LC separation, a mild supporting electrolyte for JA oxidation is required, as the supporting electrolyte solution also serves as the mobile phase of LC. Thus, a novel electrochemical derivatization with dopamine (DA) has been developed and successfully applied to the analysis of endogenous JA in wintersweet flowers and rice florets by liquid chromatography coupled with electrochemical detection (HPLC-ECD). Under optimized experimental conditions including a detection potential of +0.90 V, and 0.04 mol L(-1) acetate buffer solution (pH 5.07) : acetonitrile (67 : 33, v/v) as the mobile phase, the contents of JA in wintersweet flowers and rice florets were respectively determined to be 7.86 μg g(-1) and 308 ng g(-1), consulting the linear relationship between the peak area of JA-DA derivatives and the standard JA concentration (1.0 × 10(-7) mol L(-1) to 2.0 × 10(-5) mol L(-1), R = 0.9986) with a detection limit of 5.0 × 10(-8) mol L(-1) (S/N = 3). The results were consistent with those by LC-UV and LC-MS methods in our group, indicating that this novel pre-column electrochemical derivatization method is feasible.

  16. Comparison of hollow fiber liquid phase microextraction and dispersive liquid-liquid microextraction for the determination of organosulfur pesticides in environmental and beverage samples by gas chromatography with flame photometric detection.

    Science.gov (United States)

    Xiong, Jun; Hu, Bin

    2008-06-06

    Two methods based on hollow fiber liquid phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME), have been critically compared for the analysis of organosulfur pesticides (OSPs) in environmental and beverage samples by gas chromatography-flame photometric detection (GC-FPD). Experimental conditions including extraction solvent, solvent volume, extraction time, temperature and ionic strength have been investigated for both HF-LPME and DLLME. Under the optimal conditions, the limits of detection for the six target OSPs (malathion, chlorpyrifos, buprofezin, triazophos, carbosulfan and pyridaben) obtained by HF-LPME-GC-FPD and DLLME-GC-FPD were ranged from 1.16 microg/L to 48.48 microg/L and 0.21 microg/L to 3.05 microg/L, respectively. The relative standard deviations (RSDs, n=5) were in the range of 3.4-8.0% and 8.5-13.7%with the enrichment factors (EFs) of 27-530 and 176-946 folds for HF-LPME-GC-FPD and DLLME-GC-FPD, respectively. Both methods were found to be simple, fast, efficient, and inexpensive. Compared with HF-LPME, the advantages of DLLME technique were less extraction time, suitable for batches of samples pretreatment simultaneously, a higher extraction capacity when analyzing simple samples such as water samples. While for the analysis of complicated matrix samples such as soil and beverage samples, HF-LPME was demonstrated to be more robust and more suitable. Both methods were applied to the analysis of six OSPs in different waters, soil and beverage samples, and no target OSPs was found in these samples. For analysis of the spiked samples, the recovery of 81.7-114.4% with RSDs of 0.6-9.6% were obtained for HF-LPME, and the recovery of 78.5-117.2% with RSDs of 0.6-11.9% were obtained for DLLME.

  17. Low-density solvent-based dispersive liquid-liquid microextraction combined with single-drop microextraction for the fast determination of chlorophenols in environmental water samples by high performance liquid chromatography-ultraviolet detection.

    Science.gov (United States)

    Li, Xiaoyi; Xue, Aifang; Chen, Hao; Li, Shengqing

    2013-03-08

    A new format of fast three-phase microextraction by combining low-density solvent-based dispersive liquid-liquid microextraction (DLLME) and single-drop microextraction (SDME) was for the first time developed for the determination of chlorophenols in environmental water samples. The extraction procedure includes a 2 min DLLME pre-extraction and a 10 min SDME back-extraction. A portion of low-density solvent (toluene) was used as organic phase and injected into the aqueous sample (donor phase) with methanol as disperser. The analytes were pre-extracted into the organic phase within 2 min. A thin layer of the organic phase formed on the top of the aqueous phase by a 2 min centrifugation. Then a drop of acceptor solution was introduced into the upper layer and SDME was carried out for the back-extraction. The stirring step typically involved in SDME and LLLME is avoided with the benefit of the high speed and efficiency of DLLME pre-extraction. After extraction, the acceptor drop was withdrawn and directly injected into a high performance liquid chromatography instrument with ultraviolet detection for analysis. Five chlorophenols, 4-chlorophenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol, were selected as model compounds for developing and evaluating the method. Factors affecting extraction efficiency were studied, including the organic solvent, the disperser solvent, the composition of donor phase and acceptor phase, the volume of acceptor microdrop, and the extraction time. At optimal conditions, the method showed low detection limit (0.016-0.084 μg/L) for the five chlorophenols, good linearity (from 0.2-250 to 1.0-250 μg/L, depending on the analytes) and repeatability (RSD below 8.2, n=5). The simple, fast, and efficient feature of the proposed method was demonstrated by the analysis of chlorophenols in environmental water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Optimized Dispersive Liquid-Liquid Microextraction Method and High Performance Liquid Chromatography with Ultraviolet Detection for Simultaneous Determination of Sorbic and Benzoic Acids and Evaluation of Contamination of These Preservatives in Iranian Foods.

    Science.gov (United States)

    Javanmardi, Fardin; Arefhosseini, Seyyed Rafie; Ansarin, Masood; Nemati, Mahboob

    2015-01-01

    A rapid, simple, and sensitive dispersive liquid-liquid microextraction procedure followed by HPLC-UV was applied to determine the benzoate and sorbate in foods. The method was optimized for some variables including extraction solvent type and volume, dispersing solvent type and volume, and the effects of salt and pH. Optimum conditions were determined as follows: sample volume, 5 mL; extraction solvent (chloroform) volume, 250 μL; disperser solvent (acetone) volume, 1.2 mL; NaCl amount, 0.75 g/5 mL at pH 4. Sixty samples were analyzed, including 15 doogh, 15 fruit juice, 15 cookie, and 15 tomato paste; benzoic acid was detected in 57 samples (95%) at levels up to 448.1 μg/mL and sorbic acid in 31 samples (51.6%) at levels up to 1369 μg/mL. Under the optimum experimental conditions, the LOD and LOQ were determined as 0.1 and 0.5 μg/mL for benzoate and 0.08 and 0.3 μg/mL for sorbate, respectively. The results showed that these preservatives are commonly used at high levels in yogurt drinks (dooghs) and cookies. Also, the concentration of benzoic acid that was detected in the tomato paste and fruit juice samples was low but may affect children and sensitive persons.

  19. Mid-infrared and near-infrared spectroscopy for rapid detection of Gardeniae Fructus by a liquid-liquid extraction process.

    Science.gov (United States)

    Tao, Lingyan; Lin, Zhonglin; Chen, Jiashan; Wu, Yongjiang; Liu, Xuesong

    2017-10-25

    Gardeniae Fructus is widely used in the pharmaceutical industry, and many studies have confirmed its medical and economic value. In this study, samples collected from different liquid-liquid extraction batches of Gardeniae Fructus were detected by mid-infrared (MIR) and near-infrared (NIR) spectroscopy. Seven analytes, neochlorogenic acid (5-CQA), cryptochlorogenic acid (4-CQA), chlorogenic acid (3-CQA), geniposidic acid (GEA), deacetyl-asperulosidic acid methyl ester (DAAME), genipin-gentiobioside (GGB), and gardenoside (GA), were chosen as quality property indexes of Gardeniae Fructus. The two kinds of spectra were each used to build models by single partial least squares (PLS). Additionally, both spectral data were combined and modeled by multiblock PLS. For single spectroscopy modeling results, NIR had a better prediction for high-concentration analytes (3-CQA, DAAME, GGB, and GA) whereas MIR performed better for low-concentration analytes (5-CQA, 4-CQA, and GEA). The multiblock methodology was found to be better compared to single spectroscopy models for all seven analytes. Specifically, the coefficients of determination (R 2 ) of the NIR, MIR, and multiblock PLS calibration models of all seven components were higher than 0.95. Relative standard errors of prediction (RSEP) were all less than 7%, except for models of GGB, which were 10.36%, 13.24%, and 8.15% for the NIR-PLS, MIR-PLS, and multiblock models, respectively. These results indicate that MIR and NIR spectrographic techniques could provide a new choice for quality control in industrial production of Gardeniae Fructus. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. DETECTION AND QUANTIFICATION OF PHYTOCHEMICAL MARKERS OF Ilex paraguariensis BY LIQUID CHROMATOGRAPHY

    OpenAIRE

    Pinto,Rodrigo M. C.; Lemes,Bruna M.; Zielinski,Acácio A. F.; Klein,Traudi; Paula,Fernado de; Kist,Airton; Marques,Anna S. F.; Nogueira,Alessandro; Demiate,Ivo M.; Beltrame,Flávio L.

    2015-01-01

    Ilex paraguariensis (yerba-mate) is used as a beverage, and its extract requires adequate quality control methods in order to guarantee quality and safe use. Strategies to develop and optimize a chromatographic method to quantify theobromine, caffeine, and chlorogenic acid in I. paraguariensis extracts were evaluated by applying a quality by design (QbD) model and ultra high-performance liquid chromatography (UHPLC). The presence of these three phytochemical markers in the extracts was evalua...

  1. Toxic Compounds Analysis With High Performance Liquid Chromatography Detected By Electro Chemical Detector (Ecd)

    OpenAIRE

    Hideharu Shintaniq

    2014-01-01

    The principal area of application of high performance liquid chromatography-electrochemical detector (HPLC-ECD) has been in the analysis of naturally-occurring analytes, such as catecholamines, and pharmaceuticals in biological samples, HPLC-ECD has also applied to the analysis of pesticides and other analytes of interest to the toxicologist. In this paper, toxic area is described. In these, ammatoxins, aromatic amine, nitro-compounds, algal toxins, fungal toxins, pesticides, veterinary drug ...

  2. Phase modulation detection with liquid crystal light valve and digital holography

    Science.gov (United States)

    Residori, Stefania; Bortolozzo, Umberto; Peigné, Arnaud; Molin, Stephanie; Dolfi, Daniel; Huignard, Jean-Pierre

    2017-06-01

    Self-adaptive interferometry allows the measurement of small optical phase modulations in noisy environments and with strongly distorted optical wavefronts. We review two techniques of self-adaptive interferometers based on liquid crystals spatial light modulators, one obtained by using an optically addressed light valve, the second one realized by adopting a digital holography CMOS-LCOS scheme. The adaptive character of these two types of holographic interferometers will be analyzed and compared.

  3. Continuous liquid level detection based on two parallel plastic optical fibers in a helical structure

    Science.gov (United States)

    Zhang, Yingzi; Hou, Yulong; Zhang, Yanjun; Hu, Yanjun; Zhang, Liang; Gao, Xiaolong; Zhang, Huixin; Liu, Wenyi

    2018-02-01

    A simple and low-cost continuous liquid-level sensor based on two parallel plastic optical fibers (POFs) in a helical structure is presented. The change in the liquid level is determined by measuring the side-coupling power in the passive fiber. The side-coupling ratio is increased by just filling the gap between the two POFs with ultraviolet-curable optical cement, making the proposed sensor competitive. The experimental results show that the side-coupling power declines as the liquid level rises. The sensitivity and the measurement range are flexible and affected by the geometric parameters of the helical structure. A higher sensitivity of 0.0208 μW/mm is acquired for a smaller curvature radius of 5 mm, and the measurement range can be expanded to 120 mm by enlarging the screw pitch to 40 mm. In addition, the reversibility and temperature dependence are studied. The proposed sensor is a cost-effective solution offering the advantages of a simple fabrication process, good reversibility, and compensable temperature dependence.

  4. Fast neutron detection with {sup 6}Li-loaded liquid scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, B.M., E-mail: brian.fisher@jhuapl.edu [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Abdurashitov, J.N. [Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312 (Russian Federation); Coakley, K.J. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Gavrin, V.N. [Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312 (Russian Federation); Gilliam, D.M. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Nico, J.S., E-mail: jnico@nist.gov [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Shikhin, A.A. [Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312 (Russian Federation); Thompson, A.K. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Vecchia, D.F. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Yants, V.E. [Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312 (Russian Federation)

    2011-08-01

    We report on the development of a fast neutron detector using a liquid scintillator doped with enriched {sup 6}Li. The lithium was introduced in the form of an aqueous LiCl micro-emulsion with a di-isopropylnaphthalene-based liquid scintillator. A {sup 6}Li concentration of 0.15% by weight was obtained. A 125 mL glass cell was filled with the scintillator and irradiated with fission-source neutrons. Fast neutrons may produce recoil protons in the scintillator, and those neutrons that thermalize within the detector volume can be captured on the {sup 6}Li. The energy of the neutron may be determined by the light output from recoiling protons, and the capture of the delayed thermal neutron reduces background events. In this paper, we discuss the development of this {sup 6}Li-loaded liquid scintillator, demonstrate the operation of it in a detector, and compare its efficiency and capture lifetime with Monte Carlo simulations. Data from a boron-loaded plastic scintillator were acquired for comparison. We also present a pulse-shape discrimination method for differentiating between electronic and nuclear recoil events based on the Matusita distance between a normalized observed waveform and nuclear and electronic recoil template waveforms. The details of the measurements are discussed along with specifics of the data analysis and its comparison with the Monte Carlo simulation.

  5. Application of liquid chromatography-electrospray ionization tandem mass spectrometry to the detection of 10 sulfonamides in honey.

    Science.gov (United States)

    Verzegnassi, L; Savoy-Perroud, M C; Stadler, R H

    2002-11-15

    Liquid chromatography (LC) in combination with tandem mass spectrometry (MS-MS) has been applied to the separation and detection of 10 different sulfonamides in honey. The methodology encompasses a simple hydrolysis of the honey sample to liberate sugar-bound sulfonamides followed by liquid-liquid extraction of the 10 analytes, filtration, and analysis by LC-MS-MS. Conditions for reversed-phase LC and electrospray ionization (ESI) MS-MS in the positive ion mode were optimized for the 10 compounds under study, monitoring two characteristic mass transitions simultaneously for each analyte. The procedure is a qualitative confirmatory method for 10 sulfonamides at the low microg/kg level in honey. Typical recoveries of the analytes in honey ranged from 44 to 73% at a fortification level of 50 microg/kg. This study also addresses the issue of matrix-induced suppression of ionization, an effect often encountered in trace residue analysis of food matrices using LC-ESI-MS-MS based methods.

  6. Simultaneous determination of three curcuminoids in Curcuma longa L. by high performance liquid chromatography coupled with electrochemical detection

    Directory of Open Access Journals (Sweden)

    Yuling Long

    2014-10-01

    Full Text Available A novel method for analysis of three active components curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L. was developed by HPLC coupled with electrochemical detection. Three curcuminoids were well separated on a C18 column and detected with high sensitivity. A mobile phase containing acetonitrile and 10 mM Na2HPO4–H3PO4 (pH 5.0 (50:50, v/v was used. Good linearity was obtained in the range of 0.208–41.6, 0.197–39.4, and 0.227–114 μM for curcumin, demethoxycurcumin and bisdemethoxycurcumin respectively. The limit of detection reached up to 10−8 M, which was lower than that by UV detection. The relative standard deviations (RSDs ranged from 1.06% to 1.88% for intra-day precision and from 4.30% to 5.79% for inter-day precision, respectively. The proposed method has been applied in real herb sample and recoveries ranging from 86.3% to 111% were obtained. Keywords: Curcumin, High performance liquid chromatography, Electrochemical detection, Curcuma longa L.

  7. A cost-effective Z-folding controlled liquid handling microfluidic paper analysis device for pathogen detection via ATP quantification.

    Science.gov (United States)

    Jin, Sheng-Quan; Guo, Su-Miao; Zuo, Peng; Ye, Bang-Ce

    2015-01-15

    A cost-effective microfluidic paper analysis device (μPAD) was developed with a special Z-folding design for controlling the fluidic flowing and substrate transportation. This presented μPAD can be easily fabricated through wax printing by using a solid ink printer which deposits wax onto the surface of a chromatographic paper, and then baked on a hotplate by penetrating the molten wax into the paper to create a hydrophobic barrier. After μPAD fabrication, liquid control and substrate transportation can be easily carried out by twice folding the μPAD following Z shape. The Z folding made two separated reagent holding zone connected while the detection reaction occurred with the connection. In this paper, a pathogens detection indicated by ATP quantification was took as a proof-in-principle application of using this presented μPAD, the limit of detection (LOD) was 1 μM for ATP detection and 2.6×10(7) CFU/mL for Salmonella live cell detection, which showed a great potential for Point-of-Care Testing (POCT) applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Toxic Cyanobacteria in Svalbard: Chemical Diversity of Microcystins Detected Using a Liquid Chromatography Mass Spectrometry Precursor Ion Screening Method

    Directory of Open Access Journals (Sweden)

    Julia Kleinteich

    2018-04-01

    Full Text Available Cyanobacteria synthesize a large variety of secondary metabolites including toxins. Microcystins (MCs with hepato- and neurotoxic potential are well studied in bloom-forming planktonic species of temperate and tropical regions. Cyanobacterial biofilms thriving in the polar regions have recently emerged as a rich source for cyanobacterial secondary metabolites including previously undescribed congeners of microcystin. However, detection and detailed identification of these compounds is difficult due to unusual sample matrices and structural congeners produced. We here report a time-efficient liquid chromatography-mass spectrometry (LC-MS precursor ion screening method that facilitates microcystin detection and identification. We applied this method to detect six different MC congeners in 8 out of 26 microbial mat samples of the Svalbard Archipelago in the Arctic. The congeners, of which [Asp3, ADMAdda5, Dhb7] MC-LR was most abundant, were similar to those reported in other polar habitats. Microcystins were also determined using an Adda-specific enzyme-linked immunosorbent assay (Adda-ELISA. Nostoc sp. was identified as a putative toxin producer using molecular methods that targeted 16S rRNA genes and genes involved in microcystin production. The mcy genes detected showed highest similarities to other Arctic or Antarctic sequences. The LC-MS precursor ion screening method could be useful for microcystin detection in unusual matrices such as benthic biofilms or lichen.

  9. Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

    Science.gov (United States)

    Liu, Yong-Qiang; Yu, Hong

    2017-04-01

    A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg 2+ , Ca 2+ , and Sr 2+ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV-absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg 2+ , Ca 2+ , and Sr 2+ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg 2+ , Ca 2+ , and Sr 2+ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Determination of sulfite in dried garlic by reversed-phase ion-pairing liquid chromatography with post-column detection.

    Science.gov (United States)

    Perfetti, Gracia A; Diachenko, Gregory W

    2003-01-01

    A method is described for determining sulfite in dried garlic. Garlic is extracted with an HCl solution to inhibit the formation of allicin, which interferes with the determination of sulfite. After cleanup of the extract on a C18 solid-phase extraction column, sulfite is converted to hydroxymethylsulfonate (HMS) by adding formaldehyde and heating to 50 degrees C. HMS is determined by reversed-phase ion-pairing liquid chromatography with post-column detection. The post-column reaction system consists of the addition of KOH to convert HMS to sulfite ion, followed by the addition of 5,5'-dithiobis(2-nitrobenzoic acid) to produce 5-mercapto-2-nitrobenzoic acid which is detected spectrophotometrically at 450 nm. Background levels in unsulfited dried garlic equivalent to method for determining sulfite in garlic is discussed.

  11. Liquid nitrogen-assisted synthesis of fluorescent carbon dots from Blueberry and their performance in Fe3+ detection

    Science.gov (United States)

    Aslandaş, Ayşe Merve; Balcı, Neslihan; Arık, Mustafa; Şakiroğlu, Halis; Onganer, Yavuz; Meral, Kadem

    2015-11-01

    Fluorescent carbon dots (C-dots) were synthesized by a facile method containing liquid N2 treatment and centrifuge processes. The photophysical properties of the C-dots in an aqueous solution were examined at various conditions such as concentration, temperature, pH and excitation wavelength by using UV-vis absorption, fluorescence and time-resolved fluorescence spectroscopies. The C-dots emitted a broad fluorescence between approximately 350-550 nm and their fluorescence was tuned by changing excitation wavelength. The as-prepared C-dots were applied to Fe3+ detection from aqueous solution. Spectroscopic data revealed that the as-prepared C-dots were used to detect Fe3+ in the range of 12.5 μM to 100 μM as a fluorescence sensor.

  12. Determination of undecylenic and sorbic acids in cosmetic preparations by high performance liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Bousquet, Ennio; Spadaro, A; Santagati, N A; Scalia, S; Ronsisvalle, G

    2002-11-07

    A highly sensitive and selective method for the determination of sorbic (SA) and undecylenic acid (UA) in cosmetic formulations by a high performance liquid chromatography method with electrochemical detection (ECD) is described. The pre-column derivatizations of SA and UA and the internal standard (cyclohexanoic acid (cHA)) were carried out using 1-(2,5-dihydroxyphenyl)-2-bromoethanone (2,5-DBE) as an electroactive labeling reagent previously synthesized in our lab. The resulting electroactive esters were separated by isocratic elution of a 5 micrometer Hypersil CN column with acetonitrile-acetate buffer eluent. The compounds were detected by a porous graphite electrode set at an oxidation potential of +0.45 V. The analytical method developed in this study is suitable for quality control assays of complex cosmetic formulations containing sorbic and/or UA.

  13. Rapid determination of Papaver somniferum alkaloids in process streams using monolithic column high-performance liquid chromatography with chemiluminescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Costin, Jason W. [School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3217 (Australia); Lewis, Simon W. [Department of Applied Chemistry, Curtin University of Technology, Perth, WA 6845 (Australia); Purcell, Stuart D. [GlaxoSmithKline, Port Fairy, Victoria 3284 (Australia); Waddell, Lucy R. [GlaxoSmithKline, Port Fairy, Victoria 3284 (Australia); Francis, Paul S. [School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3217 (Australia); Barnett, Neil W. [School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3217 (Australia)]. E-mail: barnie@deakin.edu.au

    2007-07-30

    We have combined high-performance liquid chromatography (HPLC) separations using a monolithic column with acidic potassium permanganate and tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence detection in a rapid and highly sensitive method to monitor the process of extracting opiate alkaloids from Papaver somniferum. Due to the high flow rates allowed with the monolithic column and the inherent selectivity of the chemiluminescence reactions, the four predominant alkaloids - morphine, codeine, oripavine and thebaine - were determined in less than 2 min. The results obtained with numerous process samples compared favourable with those of the standard HPLC methodology. Limits of detection were 1 x 10{sup -10} M, 5 x 10{sup -10} M, 5 x 10{sup -10} M and 1 x 10{sup -9} M, for morphine, codeine, oripavine and thebaine, respectively.

  14. A novel photonic crystal fibre switch

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Hermann, D.S.; Broeng, Jes

    2003-01-01

    A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB.......A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB....

  15. Multiresidue method for detection of pesticides in beef meat using liquid chromatography coupled to mass spectrometry detection (LC-MS) after QuEChERS extraction.

    Science.gov (United States)

    Oliveira, Fabiano Aurélio da Silva; Pereira, Elba Nathália Corrêa; Gobbi, Jennifer Mattedi; Soto-Blanco, Benito; Melo, Marília Martins

    2018-01-01

    Beef meat is an important food that can be contaminated by pesticides. This study aimed to optimize a multiresidue method for identification and quantification of pesticides in beef meat by liquid chromatography coupled to mass spectrometry detection (LC-MS). The extraction and clean-up procedures were adapted from the QuECHERS method. From the 188 analytes tested, the method was validated as qualitative method for 19 compounds and as quantitative method for 152 compounds. The results were satisfactory, yielding coefficients of variation of less than 20% and recoveries ranging from 70% to 120% and expanded uncertainty of less than 50%. The quantification limit was typically 10 µg kg -1 (but 25 µg kg -1 for 12 of the compounds) and the detection limit was 5.0 µg kg -1 . Thirty-two real samples of commercialized beef meat were analyzed without any residual pesticide being found. Thus, the results showed that the multiresidue method for detecting 171 pesticides, using adapted QuECHERS for extraction and LC-MS for detection, is suitable for analyzing beef meat.

  16. Poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide nanosheets for electrochemically detecting dopamine at low concentration

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Hui; Liang, Jiachen; Ji, Chunguang; Zhang, Haifeng; Pei, Qi; Zhang, Yuyang; Zhang, Yu [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China); Hisaeda, Yoshio [Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Song, Xi-Ming, E-mail: songlab@lnu.edu.cn [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China); Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2016-08-01

    Poly(3-(1-vinylimidazolium-3-yl)propane-1-sulfonate) (PVIPS), a novel kind of poly(zwitterionic liquids) (PZILs) containing both imidazolium cation and sulfonate anion, was successfully modified on the surface of polypyrrole/graphene oxide nanosheets (PPy/GO) by covalent bonding. The obtained novel PZILs functionalized PPy/GO nanosheets (PVIPS/PPy/GO) modified glassy carbon electrode (GCE) presented the excellent electrochemical catalytic activity towards dopamine (DA) with high stability, sensitivity, selectivity and wide linear range (40–1220 nM), especially having a lower detection limit (17.3 nM). The excellent analytical performance is attributed to the strongly negative charges on the surface of modified GCE in aqueous solution, which is different from conventional poly(ionic liquids) modified GCE. DA cations could be quickly enriched on the electrode surface by electrostatic interaction in solution due to the existence of −SO{sub 3}{sup −} groups with negative charge at the end of pendant groups in zwitterionic PVIPS, resulting in a change of the electrons transmission mode in the oxidation of DA, that is, from a typical diffusion-controlled process at conventional poly(1-vinyl-3-ethylimidazole bromide) (PVEIB)/PPy/GO modified GCE to a typical surface-controlled process. - Graphical Abstract: Novel poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide nanosheets were successfully synthesized and presented an excellent performance for determination to DA. Display Omitted - Highlights: • Zwitterionic PVIPS functionalized PPy/GO nanosheets were successfully synthesized. • Their surface charge property has been obviously changed to electronegativity. • The excellent electrochemical catalytic activities towards DA were achieved. • −SO{sub 3}{sup −} groups with negative charge changed the transmission mode of electrons. • PVIPS/PPy/GO can act as an electrode material for detecting DA at low concentration.

  17. High-performance liquid chromatographic assay of parabens in wash-off cosmetic products and foods using chemiluminescence detection

    International Nuclear Information System (INIS)

    Zhang Qunlin; Lian Mei; Liu Lijuan; Cui Hua

    2005-01-01

    A new method for the simultaneous determination of parabens including methylparaben, ethylparaben, propylparaben, and butylparaben by high-performance liquid chromatography (HPLC) coupled with chemiluminescence detection was developed. The procedure was based on the chemiluminescent enhancement by parabens of the cerium(IV)-rhodamine 6G system in the strong sulfuric acid medium. The good separation of parabens was carried out with an isocratic elution using a mixture of methanol and water (60:40, v/v) within 8.5 min. Under the optimized conditions, a linear working range extends three orders of magnitude with the relative standard deviations of intra- and inter-day precision below 4.5%, and the detection limits were 1.9 x 10 -9 , 2.7 x 10 -9 , 3.9 x 10 -9 , and 5.3 x 10 -9 g ml -1 for methylparaben, ethylparaben, propylparaben, and butylparaben, respectively. The chemiluminescence reaction was well compatible with the mobile phase of high-performance liquid chromatography. The proposed method has been successfully applied to the assay of parabens in wash-off cosmetic products and foods with the minimal sample preparation

  18. Rapid and sensitive determination of carbohydrates in foods using high temperature liquid chromatography with evaporative light scattering detection.

    Science.gov (United States)

    Terol, Amanda; Paredes, Eduardo; Maestre, Salvador E; Prats, Soledad; Todolí, José L

    2012-04-01

    In the present work, an evaporative light scattering detector was used as a high-temperature liquid chromatography detector for the determination of carbohydrates. The compounds studied were glucose, fructose, galactose, sucrose, maltose, and lactose. The effect of column temperature on the retention times and detectability of these compounds was investigated. Column heating temperatures ranged from 25 to 175°C. The optimum temperature in terms of peak resolution and detectability with pure water as mobile phase and a liquid flow rate of 1 mL/min was 150°C as it allowed the separation of glucose and the three disaccharides here considered in less than 3 min. These conditions were employed for lactose determination in milk samples. Limits of quantification were between 2 and 4.7 mg/L. On the other hand, a temperature gradient was developed for the simultaneous determination of glucose, fructose, and sucrose in orange juices, due to coelution of monosaccharides at temperatures higher than 70°C, being limits of quantifications between 8.5 and 12 mg/L. The proposed hyphenation was successfully applied to different types of milk and different varieties of oranges and mandarins. Recoveries for spiked samples were close to 100% for all the studied analytes. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A novel derivatization-free method of formaldehyde and propylene glycol determination in hydrogels by liquid chromatography with refractometric detection.

    Science.gov (United States)

    Isakau, Henadz; Robert, Marielle; Shingel, Kirill I

    2009-04-05

    The paper describes the development and validation of a new derivatization-free liquid chromatography method for simultaneous determination of propylene glycol and formaldehyde in the formulations containing formaldehyde-releasing preservative. Highly swollen hydrogel made of poly(ethylene glycol)-protein conjugates was taken as a model formulation for integration of the propylene glycol and the diazolydinyl urea as formaldehyde releaser. The method is shown to be simple and selective and, more importantly, allows determining an existing level of formaldehyde at the moment of analysis instead of all available formaldehyde that might be released during chemical derivatization. After liquid extraction the propylene glycol (PG) and formaldehyde (FA) amounts are determined chromatographically on a Shodex SH 1011 ligand-exchange column using 0.01 M sulfuric acid mobile phase, a flow rate of 1.0 ml/min and RI detection. The assay is validated showing good linearity, precision, and accuracy. The limits of detection of formaldehyde and propylene glycol in the analyzed solutions were estimated to be 25 ng and 87 ng, respectively. This analytical assay is considered useful for product stability studies and in developing new formaldehyde releaser-containing formulations where the concentration of formaldehyde is a presumable subject of labeling requirements. This method can also provide a rapid and convenient alternative to gas chromatography method of propylene glycol quantification.

  20. High-performance liquid chromatographic assay of parabens in wash-off cosmetic products and foods using chemiluminescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qunlin [Department of Chemistry, University of Science and Technology of China, Jinzai Road 96, Hefei, Anhui 230026 (China); Lian Mei [Department of Chemistry, University of Science and Technology of China, Jinzai Road 96, Hefei, Anhui 230026 (China); Liu Lijuan [Department of Chemistry, University of Science and Technology of China, Jinzai Road 96, Hefei, Anhui 230026 (China); Cui Hua [Department of Chemistry, University of Science and Technology of China, Jinzai Road 96, Hefei, Anhui 230026 (China)]. E-mail: hcui@ustc.edu.cn

    2005-04-29

    A new method for the simultaneous determination of parabens including methylparaben, ethylparaben, propylparaben, and butylparaben by high-performance liquid chromatography (HPLC) coupled with chemiluminescence detection was developed. The procedure was based on the chemiluminescent enhancement by parabens of the cerium(IV)-rhodamine 6G system in the strong sulfuric acid medium. The good separation of parabens was carried out with an isocratic elution using a mixture of methanol and water (60:40, v/v) within 8.5 min. Under the optimized conditions, a linear working range extends three orders of magnitude with the relative standard deviations of intra- and inter-day precision below 4.5%, and the detection limits were 1.9 x 10{sup -9}, 2.7 x 10{sup -9}, 3.9 x 10{sup -9}, and 5.3 x 10{sup -9} g ml{sup -1} for methylparaben, ethylparaben, propylparaben, and butylparaben, respectively. The chemiluminescence reaction was well compatible with the mobile phase of high-performance liquid chromatography. The proposed method has been successfully applied to the assay of parabens in wash-off cosmetic products and foods with the minimal sample preparation.

  1. Determination of neurotransmitters and their metabolites using one- and two-dimensional liquid chromatography with acidic potassium permanganate chemiluminescence detection.

    Science.gov (United States)

    Holland, Brendan J; Conlan, Xavier A; Stevenson, Paul G; Tye, Susannah; Reker, Ashlie; Barnett, Neil W; Adcock, Jacqui L; Francis, Paul S

    2014-09-01

    High-performance liquid chromatography with chemiluminescence detection based on the reaction with acidic potassium permanganate and formaldehyde was explored for the determination of neurotransmitters and their metabolites. The neurotransmitters norepinephrine and dopamine were quantified in the left and right hemispheres of rat hippocampus, nucleus accumbens and prefrontal cortex, and the metabolites vanillylmandelic acid, 3,4-dihydrophenylacetic acid, 5-hydroxyindole-3-acetic acid and homovanillic acid were identified in human urine. Under optimised chemiluminescence reagent conditions, the limits of detection for these analytes ranged from 2.5 × 10(-8) to 2.5 × 10(-7) M. For the determination of neurotransmitter metabolites in urine, a two-dimensional high-performance liquid chromatography (2D-HPLC) separation operated in heart-cutting mode was developed to overcome the peak capacity limitations of the one-dimensional separation. This approach provided the greater separation power of 2D-HPLC with analysis times comparable to conventional one-dimensional separations.

  2. Application of high-speed counter-current chromatography coupled with high-performance liquid chromatography-diode array detection for the preparative isolation and purification of hyperoside from Hypericum perforatum with online purity monitoring.

    Science.gov (United States)

    Zhou, Tingting; Chen, Bin; Fan, Guorong; Chai, Yifeng; Wu, Yutian

    2006-05-26

    Following preparative isolation and purification by high-speed counter-current chromatography (HSCCC), the collected fractions were generally analyzed by high-performance liquid chromatography (HPLC) to determine the relative purities of each fraction. Our paper reports for the first time a preparative isolation-purity detection hyphenated system: online coupling of HSCCC with high-performance liquid chromatography-diode array detection (HSCCC-HPLC-DAD). The introduction of online purity analysis in HSCCC has dramatically improved the efficiency of this technique by overcoming the drawbacks of post analysis in HSCCC isolation. The effluent from the outlet of HSCCC was splitted into two parts: one was collected, while the other was introduced directly into an HPLC-DAD system for purity analysis through a switch valve. Therefore, the purities of the obtained fractions from HSCCC were monitored, and fractions with high purities were collected. This strategy has been successfully demonstrated with the preparative isolation and purification of hyperoside from Hypericum perforatum (St. Jone's Wort); a model of TBE-300A HSCCC was used to isolate and separate hyperoside from H. perforatum with a two-phase solvent system composed of ethyl acetate-ethanol-water at the volume ratio of 5:1:5 (v/v) using online detection technique. The isolation was done in less than 3.5 h, and a total of 83.0-mg hyperoside at over 99.0% purity was yielded from 300 mg of the partially purified extract. This new strategy possesses general utility in the preparation of bioactive compounds from traditional Chinese medicine (TCM).

  3. The effects of compressive stress and contamination liquids on the ultrasonic detection of fatigue cracks

    International Nuclear Information System (INIS)

    Wooldridge, A.B.

    1980-01-01

    The influence of compressive stress on the reflection and transmission of ultrasound has been investigated for fatigue cracks. An examination has been made of the shear wave corner echoes from surface breaking fatigue cracks which were grown at constant stress intensity factor to control the roughness of the faces. In this way a correlation has been established between the roughness of the surfaces and the ultrasonic response at both zero load and under stress. The effect of liquids in the cracks has also been studied and the results compared with theoretical predictions for a thin sided parallel gap. (author)

  4. Detection of co-ion extraction in liquid/supercritical CO2 using QCM

    International Nuclear Information System (INIS)

    Yoon, C. H.; Ko, M. S.; Park, K. H.; Kim, H. D.; Kim, H. W.

    2002-01-01

    The behaviors of Quartz Crystal Microbalance(QCM) were analyzed in liquid and supercritical carbon dioxide. 5 MHz-QCM was purchased and inserted into the high pressure cell with a feed-through that connects QCM and frequency measurement devices. The frequency of QCM turned out to be a function of pressure, properties of ambient fluid, and mass on the surfaces of QCM. After calibration of these effects, we applied QCM to the measurement of co-ion dissolution into carbon dioxide. Cyanex was a additive that dissolve co ions. The solubility of co ions was obtained

  5. Improved detection of multiple environmental antibiotics through an optimized sample extraction strategy in liquid chromatography-mass spectrometry analysis.

    Science.gov (United States)

    Yi, Xinzhu; Bayen, Stéphane; Kelly, Barry C; Li, Xu; Zhou, Zhi

    2015-12-01

    A solid-phase extraction/liquid chromatography/electrospray ionization/multi-stage mass spectrometry (SPE-LC-ESI-MS/MS) method was optimized in this study for sensitive and simultaneous detection of multiple antibiotics in urban surface waters and soils. Among the seven classes of tested antibiotics, extraction efficiencies of macrolides, lincosamide, chloramphenicol, and polyether antibiotics were significantly improved under optimized sample extraction pH. Instead of only using acidic extraction in many existing studies, the results indicated that antibiotics with low pK a values (antibiotics with high pK a values (>7) were extracted more efficiently under neutral conditions. The effects of pH were more obvious on polar compounds than those on non-polar compounds. Optimization of extraction pH resulted in significantly improved sample recovery and better detection limits. Compared with reported values in the literature, the average reduction of minimal detection limits obtained in this study was 87.6% in surface waters (0.06-2.28 ng/L) and 67.1% in soils (0.01-18.16 ng/g dry wt). This method was subsequently applied to detect antibiotics in environmental samples in a heavily populated urban city, and macrolides, sulfonamides, and lincomycin were frequently detected. Antibiotics with highest detected concentrations were sulfamethazine (82.5 ng/L) in surface waters and erythromycin (6.6 ng/g dry wt) in soils. The optimized sample extraction strategy can be used to improve the detection of a variety of antibiotics in environmental surface waters and soils.

  6. DETECTION AND QUANTIFICATION OF PHYTOCHEMICAL MARKERS OF Ilex paraguariensis BY LIQUID CHROMATOGRAPHY

    Directory of Open Access Journals (Sweden)

    Rodrigo M. C. Pinto

    2015-11-01

    Full Text Available Ilex paraguariensis (yerba-mate is used as a beverage, and its extract requires adequate quality control methods in order to guarantee quality and safe use. Strategies to develop and optimize a chromatographic method to quantify theobromine, caffeine, and chlorogenic acid in I. paraguariensis extracts were evaluated by applying a quality by design (QbD model and ultra high-performance liquid chromatography (UHPLC. The presence of these three phytochemical markers in the extracts was evaluated using UHPLC-MS and was confirmed by the chromatographic bands in the total ion current traces (m/z of 181.1 [M+H]+, 195.0 [M+H]+, and 353.0 [M−H]−, respectively. The developed method was then transferred to a high-performance liquid chromatography (HPLC platform, and the three phytochemical markers were used as external standards in the validation of a method for analyses of these compounds in extracts using a diode array detector (DAD. The validated method was applied to quantify the chlorogenic acid, caffeine, and theobromine in the samples. HPLC-DAD chromatographic fingerprinting was also used in a multivariate approach to process the entire data and to separate the I. paraguariensis extracts into two groups. The developed method is very useful for qualifying and quantifying I. paraguariensis extracts.

  7. Detection of various freshwater cyanobacterial toxins using ultra-performance liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Oehrle, Stuart A; Southwell, Ben; Westrick, Judy

    2010-05-01

    Several freshwater cyanobacteria species have the capability to produce toxic compounds, frequently referred to as cyanotoxins. The most prevalent of these cyanotoxins is microcystin LR. Recognizing the potential health risk, France, Italy, Poland, Australia, Canada, and Brazil have set either standards or guidelines for the amount of microcystin LR permissible in drinking water based on the World Health Organization guideline of one microg/L of microcystin LR. Recently, the United States Environmental Protection Agency has begun to evaluate the occurrence and health effects of cyanotoxins and their susceptibility to water treatment under the Safe Drinking Water Act through the Contaminant Candidate List (CCL). A recent update of the Contaminant Candidate List focuses research and data collection on the cyanotoxins microcystin LR, anatoxin-a, and cylindrospermopsin. Liquid Chromatography/Tandem-Mass Spectrometry (LC/MS/MS) is a powerful tool for the analysis of various analytes in a wide variety of matrices because of its sensitivity and selectivity. The use of smaller column media (sub 2 microm particles) was investigated to both improve the speed, sensitivity and resolution, and to quantify the CCL cyanotoxins, in a single analysis, using Ultra-Performance Liquid Chromatography (UPLC) combined with tandem mass spectrometry. Natural waters and spiked samples were analyzed to show proof-of-performance. The presented method was able to clearly resolve each of the cyanotoxins in less than eight minutes with specificity and high spike recoveries. Copyright 2009 Elsevier Ltd. All rights reserved.

  8. Jet expansion module for liquid-sampled GC-discharge ionization detection of liquefied gases.

    Science.gov (United States)

    May, Michael; Poeppelmeier, Todd; Kuo, John

    2003-03-01

    A rugged jet expansion module was designed, built, and utilized to sample liquefied gas for gas chromatography-discharge ionization detector (GC-DID) analysis. The module is inserted at an intermediate stage between a higher pressure sample cylinder and lower pressure gas injection manifold. The title jet module permits selection of liquid-phase or vapor-phase sampling by setting the valve-cylinder orientation up or down (relative to gravity). It consists of a four-way stainless steel cross, plus the following components connected to pipe thread ports: (1) mechanical pressure gauge, -15 to +30 psig; (2) threaded nut with 0.010-in. jet orifice (connect to sample cylinder valve); (3) bellows valve (connect to GC manifold); (4) bellows valve (connect to expansion cylinder). Making use of the jet module, measurement of air concentration in [15N]ammonia and sulfur hexafluoride (single-component) samples was found to be significantly lower in the liquid phase by GC-DID. This compact apparatus enables phase-selective sampling, reduces primary manifold contamination, and improves operator safety.

  9. A highly selective dispersive liquid-liquid microextraction approach based on the unique fluorous affinity for the extraction and detection of per- and polyfluoroalkyl substances coupled with high performance liquid chromatography tandem-mass spectrometry.

    Science.gov (United States)

    Wang, Juan; Shi, Yali; Cai, Yaqi

    2018-04-06

    In the present study, a highly selective fluorous affinity-based dispersive liquid-liquid microextraction (DLLME) technique was developed for the extraction and analysis of per- and polyfluoroalkyl substances (PFASs) followed by high performance liquid chromatography tandem-mass spectrometry. Perfluoro-tert-butanol with multiple C-F bonds was chosen as the extraction solvent, which was injected into the aqueous samples with a dispersive solvent (acetonitrile) in a 120:800 (μL, v/v) mixture for PFASs enrichment. The fluorous affinity-based extraction mechanism was confirmed by the significantly higher extraction recoveries for PFASs containing multiple fluorine atoms than those for compounds with fewer or no fluorine atoms. The extraction recoveries of medium and long-chain PFASs (CF 2  > 5) exceeded 70%, except perfluoroheptanoic acid, while those of short-chain PFASs were lower than 50%, implying that the proposed DLLME may not be suitable for their extraction due to weak fluorous affinity. This highly fluoroselective DLLME technique can greatly decrease the matrix effect that occurs in mass spectrometry detection when applied to the analysis of urine samples. Under the optimum conditions, the relative recoveries of PFASs with CF 2  > 5 ranged from 80.6-121.4% for tap water, river water and urine samples spiked with concentrations of 10, 50 and 100 ng/L. The method limits of quantification for PFASs in water and urine samples were in the range of 0.6-8.7 ng/L. Furthermore, comparable concentrations of PFASs were obtained via DLLME and solid-phase extraction, confirming that the developed DLLME technique is a promising method for the extraction of PFASs in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. High performance liquid chromatography-charged aerosol detection applying an inverse gradient for quantification of rhamnolipid biosurfactants.

    Science.gov (United States)

    Behrens, Beate; Baune, Matthias; Jungkeit, Janek; Tiso, Till; Blank, Lars M; Hayen, Heiko

    2016-07-15

    A method using high performance liquid chromatography coupled to charged-aerosol detection (HPLC-CAD) was developed for the quantification of rhamnolipid biosurfactants. Qualitative sample composition was determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The relative quantification of different derivatives of rhamnolipids including di-rhamnolipids, mono-rhamnolipids, and their precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) differed for two compared LC-MS instruments and revealed instrument dependent responses. Our here reported HPLC-CAD method provides uniform response. An inverse gradient was applied for the absolute quantification of rhamnolipid congeners to account for the detector's dependency on the solvent composition. The CAD produces a uniform response not only for the analytes but also for structurally different (nonvolatile) compounds. It was demonstrated that n-dodecyl-β-d-maltoside or deoxycholic acid can be used as alternative standards. The method of HPLC-ultra violet (UV) detection after a derivatization of rhamnolipids and HAAs to their corresponding phenacyl esters confirmed the obtained results but required additional, laborious sample preparation steps. Sensitivity determined as limit of detection and limit of quantification for four mono-rhamnolipids was in the range of 0.3-1.0 and 1.2-2.0μg/mL, respectively, for HPLC-CAD and 0.4 and 1.5μg/mL, respectively, for HPLC-UV. Linearity for HPLC-CAD was at least 0.996 (R(2)) in the calibrated range of about 1-200μg/mL. Hence, the here presented HPLC-CAD method allows absolute quantification of rhamnolipids and derivatives. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Critical Evaluation of Acetylcholine Determination in Rat Brain Microdialysates using Ion-Pair Liquid Chromatography with Amperometric Detection

    Directory of Open Access Journals (Sweden)

    Yvette Michotte

    2008-08-01

    Full Text Available Liquid chromatography with amperometric detection remains the most widely used method for acetylcholine quantification in microdialysis samples. Separation of acetylcholine from choline and other matrix components on a microbore chromatographic column (1 mm internal diameter, conversion of acetylcholine in an immobilized enzyme reactor and detection of the produced hydrogen peroxide on a horseradish peroxidase redox polymer coated glassy carbon electrode, achieves sufficient sensitivity for acetylcholine quantification in rat brain microdialysates. However, a thourough validation within the concentration range required for this application has not been carried out before. Furthermore, a rapid degradation of the chromatographic columns and enzyme systems have been reported. In the present study an ion-pair liquid chromatography assay with amperometric detection was validated and its long-term stability evaluated. Working at pH 6.5 dramatically increased chromatographic stability without a loss in sensitivity compared to higher pH values. The lower limit of quantification of the method was 0.3 nM. At this concentration the repeatability was 15.7%, the inter-day precision 8.7% and the accuracy 103.6%. The chromatographic column was stable over 4 months, the immobilized enzyme reactor up to 2-3 months and the enzyme coating of the amperometric detector up to 1-2 months. The concentration of acetylcholine in 30 μl microdialysates obtained under basal conditions from the hippocampus of freely moving rats was 0.40 ± 0.12 nM (mean ± SD, n = 30. The present method is therefore suitable for acetylcholine determination in rat brain microdialysates.

  12. Study of light detection and sensitivity for a ton-scale liquid xenon dark matter detector

    International Nuclear Information System (INIS)

    Wei, Y; Lin, Q; Xiao, X; Ni, K

    2013-01-01

    Ton-scale liquid xenon detectors operated in two-phase mode are proposed and being constructed recently to explore the favored parameter space for the Weakly Interacting Massive Particles (WIMPs) dark matter. To achieve a better light collection efficiency while limiting the number of electronics channels compared to the previous generation detectors, large-size photo-multiplier tubes (PMTs) such as the 3-inch-diameter R11410 from Hamamatsu are suggested to replace the 1-inch-square R8520 PMTs. In a two-phase xenon dark matter detector, two PMT arrays on the top and bottom are usually used. In this study, we compare the performance of two different ton-scale liquid xenon detector configurations with the same number of either R11410 (config.1) or R8520 (config.2) for the top PMT array, while both using R11410 PMTs for the bottom array. The self-shielding of liquid xenon suppresses the background from the PMTs and the dominant background is from the pp solar neutrinos in the central fiducial volume. The light collection efficiency for the primary scintillation light is largely affected by the xenon purity and the reflectivity of the reflectors. In the optimistic situation with a 10 m light absorption length and a 95% reflectivity, the light collection efficiency is 43%(34%) for config.1(config.2). In the conservative situation with a 2.5 m light absorption length and a 85% reflectivity, the value is only 18%(13%) for config.1(config.2). The difference between the two configurations is due to the larger PMT coverage on the top for config.1. The slightly different position resolutions for the two configurations have a negligible effect on the sensitivity. Based on the above considerations, we estimate the sensitivity reach of the two detector configurations. Both configurations can reach a sensitivity of 2 ∼ 3 × 10 −47 cm 2 for spin-independent WIMP-nucleon cross section for 100 GeV/c 2 WIMPs after two live-years of operation. The one with R8520 PMTs for the top

  13. Simultaneous Determination of Celecoxib, Erlotinib, and its Metabolite Desmethyl-Erlotinib (OSI-420) in Rat Plasma by Liquid chromatography/Tandem Mass Spectrometry with Positive/Negative Ion-Switching Electrospray Ionisation.

    Science.gov (United States)

    Thappali, Satheeshmanikandan R S; Varanasi, Kanthikiran; Veeraraghavan, Sridhar; Arla, Rambabu; Chennupati, Sandhya; Rajamanickam, Madheswaran; Vakkalanka, Swaroop; Khagga, Mukkanti

    2012-01-01

    A new method for the simultaneous determination of celecoxib, erlotinib, and its active metabolite desmethyl-erlotinib (OSI-420) in rat plasma, by liquid chromatography/tandem mass spectrometry with positive/negative ion-switching electrospray ionization mode, was developed and validated. Protein precipitation with methanol was selected as the method for preparing the samples. The analytes were separated on a reverse-phase C(18) column (50mm×4.6mm i.d., 3μ) using methanol: 2 mM ammonium acetate buffer, and pH 4.0 as the mobile phase at a flow rate 0.8 mL/min. Sitagliptin and Efervirenz were used as the internal standards for quantification. The determination was carried out on a Theremo Finnigan Quantam ultra triple-quadrupole mass spectrometer, operated in selected reaction monitoring (SRM) mode using the following transitions monitored simultaneously: positive m/z 394.5→278.1 for erlotinib, m/z 380.3→278.1 for desmethyl erlotinib (OSI-420), and negative m/z -380.1→ -316.3 for celecoxib. The limits of quantification (LOQs) were 1.5 ng/mL for Celecoxib, erlotinib, and OSI-420. Within- and between-day accuracy and precision of the validated method were within the acceptable limits of < 15% at all concentrations. The quantitation method was successfully applied for the simultaneous estimation of celecoxib, erlotinib, and desmethyl erlotinib in a pharmacokinetic study in Wistar rats.

  14. Volatile Compounds Detected in Coconut Shell Liquid Smoke through Pyrolysis at a Fractioning Temperature of 350-420 C

    Directory of Open Access Journals (Sweden)

    Ruslin Hadanu

    2016-09-01

    Full Text Available This study evaluated the volatile components of liquid smoke from coconut shells obtained through the pyrolysis process at fraction 350-420 °C. The volatile compounds of liquid smoke from a coconut shell were analyzed using gas chromatography and mass spectrometry (GC-MS. Nineteen peaks were detected by GC-MS in the coconut shell liquid smoke, and 19 compounds also were identified. The volatile compounds were identified as follows based on their function group’s composition percentage: phenol (90.75%, carbonyl (3.71%, alcohol (1.81%, and benzene (3.73%, respectively. The liquid smoke contains a high ratio of phenol derivatives (90.75% in volatile profile. The phenol derivatives were the major volatile compounds found in the coconut shell liquid smoke.

  15. Usage of liquid scintillation counting for detecting the chemiluminescence of cells and its application in medicine

    International Nuclear Information System (INIS)

    Li Tianxing; Liang Qizhong; Zou Xiaowei; Yang Zhaohen; Huang Yong; Li Huaqiang

    1995-01-01

    The liquid scintillator counting-chemiluminescence (LSC-CL) of mono-photon radiance is a sensitive, handy and high-autoanalytic technique. Through measuring basic CL, dependent CL and maximum phagocytic CL of polymorphonuclear (PMN), we studied best factor levels of the method with orthogonal design [L 9 (3 4 )]. The results showed the peak forms changed markedly (inter-group P -4 M). PMN-CL in blood was measured during acute attack of the old patients with chronic bronchitis and the children with pneumonia bronchial. It was suggested that PMN phagocytosis decreased. So the dynamic analysis of maximum phagocytic CL would help us with the deep going clinical researches of the mechanisms of anti-inflammation and injuring by the oxygen free radicals

  16. 2-Alkylcyclobutanones as makers in the detection of irradiated liquid egg -a modified method of processing

    International Nuclear Information System (INIS)

    Ammon, J.; Mildau, G.; Vater, N.

    1994-01-01

    Drying for several hours at 100 C may result in a considerable loss of 2-alkylcyclobutanones. It also tends to lead to interfering peaks so that results obtained by mass spectrometry in connection with the SIM technique may wrongly suggest the presence of small amounts of 2-alkylcyclobutanones. An alternative to this procedure is offered by lyophilization. This method also has its limitations in that it is largely dependent upon the available facilities and conditions of lyophilization (duration, vacuum, sample heating). It would therefore appear wise for any laboratory to thoroughly analyze the recovery rate of its lyophilization plant and, if required, to resort to other methods of drying (like short-term drying for 2 h at 100 C). The North Hessian Supervisory Office recommends to avoid drying altogether. Instead, liquid egg should be mixed with large quantities of sodium sulfate and then directly subjected to fat extraction using the Soxhlet apparatus (recovery rate approx. 90%). (orig./vhe) [de

  17. Simultaneous Detection of Sulfamethoxazole, Diclofenac, Carbamazepine, and Bezafibrate by Solid Phase Extraction and High Performance Liquid Chromatography with Diode Array Detection

    Science.gov (United States)

    Zhou, Z.; Jiang, J.-Q.

    2014-05-01

    A method of solid phase extraction (SPE) coupled with high performance liquid chromatography and diode array detection (HPLC-DAD) was studied for the simultaneous determination of sulfamethoxazole (SMX), diclofenac (DCF), carbamazepine (CBZ), and bezafi brate (BZF) in test solutions. The target compounds were extracted by SPE from samples, and the resulting elutes were analyzed using a HPLC-DAD system at wavelengths of 270, 280, 290, and 230 nm for SMX, DCF, CBZ, and BZF, respectively. This method shows good recoveries for SMX, DCF, CBZ, and BZF with mean recoveries of 89.7 ± 9.3%, 86.1 ± 7.6%, 95.0 ± 6.5%, and 94.0 ± 5.4%, respectively.

  18. The preparation effect in task switching: carryover of SOA.

    Science.gov (United States)

    Altmann, Erik M

    2004-01-01

    A common finding in task-switching studies is switch preparation (commonly known as the preparation effect), in which a longer interval between task cue and trial stimulus (i.e., a longer stimulus onset asynchrony, or SOA) reduces the cost of switching to a different task. Three experiments link switch preparation to within-subjects manipulations of SOA. In Experiment 1, SOA was randomized within subjects, producing switch preparation that was more pronounced when the SOA switched from the previous trial than when the SOA repeated. In Experiment 2, SOA was blocked within subjects, producing switch preparation but not on the first block of trials. In Experiment 3, SOA was manipulated between subjects with sufficient statistical power to detect switch preparation, but the effect was absent. The results favor an encoding view of cognitive control, but show that any putative switching mechanism reacts lazily when exposed to only one SOA.

  19. Note: A unibody NIR transmission probe for in situ liquid detection

    Science.gov (United States)

    Wang, Huijie; Wang, Yang; Ma, Xiangyun; Zhao, Yang; Chen, Da; Chen, Wenliang; Xu, Kexin; Li, Qifeng

    2018-03-01

    The transmission probe is widely used for in situ spectroscopic detection in various fields. Conventional transmission probes are always assembled from parts, which require accurate assembly and good sealing. In this paper, a universal and reliable near-infrared (NIR) transmission probe is proposed, which is simply made up of a unibody fused silica rod. The proposed NIR transmission probe has been successfully used to measure the alcohol by volume of the Chinese spirit for quality control. This unibody NIR transmission probe has great potential for the detection of corrosive substances, owing to the good chemical resistance.

  20. Multi-colorimetric sensor array for detection of explosives in gas and liquid phase

    DEFF Research Database (Denmark)

    Kostesha, Natalie; Alstrøm, Tommy Sonne; Johnsen, C.

    2011-01-01

    In the framework of the research project "Xsense" at the Technical University of Denmark (DTU) we are developing a simple colorimetric sensor array which can be useful in detection of explosives like DNT, TATP, HMX, RDX and identification of reagents needed for making homemade explosives. The tec......In the framework of the research project "Xsense" at the Technical University of Denmark (DTU) we are developing a simple colorimetric sensor array which can be useful in detection of explosives like DNT, TATP, HMX, RDX and identification of reagents needed for making homemade explosives....... This sensor array is inexpensive, and can potentially be produced as single use disposable....

  1. Fault tolerant control for switched linear systems

    CERN Document Server

    Du, Dongsheng; Shi, Peng

    2015-01-01

    This book presents up-to-date research and novel methodologies on fault diagnosis and fault tolerant control for switched linear systems. It provides a unified yet neat framework of filtering, fault detection, fault diagnosis and fault tolerant control of switched systems. It can therefore serve as a useful textbook for senior and/or graduate students who are interested in knowing the state-of-the-art of filtering, fault detection, fault diagnosis and fault tolerant control areas, as well as recent advances in switched linear systems.  

  2. Towards early detection of the hydrolytic degradation of poly(bisphenol A)carbonate by hyphenated liquid chromatography and comprehensive two-dimensional liquid chromatography

    NARCIS (Netherlands)

    Coulier, L.; Kaal, E.R.; Hankemeier, Th.

    2006-01-01

    The hydrolytic degradation of poly(bisphenol A)carbonate (PC) has been characterized by various liquid chromatography techniques. Size exclusion chromatography (SEC) showed a significant decrease in molecular mass as a result of hydrolytic degradation, while 'liquid chromatography at critical

  3. Development of Multifunctional Ultra-Nonlinear Liquids and Liquid Crystals for Sensor Protection Applications

    National Research Council Canada - National Science Library

    Khoo, I. C

    2008-01-01

    .... Significant breakthroughs have been achieved in developing supra-nonlinear liquid crystalline films that possess extraordinarily large photorefractive responses, low switching thresholds and useful...

  4. Diode laser-based detection in liquid chromatography and capillary electrophoresis.

    NARCIS (Netherlands)

    Mank, A.J.G.; Lingeman, H.; Gooijer, C.

    1996-01-01

    Detection techniques involving diode lasers are increasingly of interest in separation science, Diode lasers are small and inexpensive and have a very stable output. However, diode lasers emitting at wavelengths shorter than 635 nm are not commercially available. This seriously limits the

  5. Fluctuation-induced switching and the switching path distribution.

    Science.gov (United States)

    Dykman, Mark

    2009-03-01

    Fluctuation-induced switching is at the root of diverse phenomena currently studied in Josephson junctions, nano-mechanical systems, nano-magnets, and optically trapped atoms. In a fluctuation leading to switching the system must overcome an effective barrier, making switching events rare, for low fluctuation intensity. We will provide an overview of the methods of finding the switching barrier for systems away from thermal equilibrium. Generic features of the barrier, such as scaling with the system parameters, will be discussed. We will also discuss the motion of the system in switching and the ways of controlling it. Two major classes of systems will be considered: dynamical systems, where fluctuations are induced by noise, and birth-death systems. Even though the motion during switching is random, the paths followed in switching form a narrow tube in phase space of the system centered at the most probable path. The paths distribution is generally Gaussian and has specific features, which have been seen in the experiment [1]. Finding the most probable path itself can be reduced to solving a problem of Hamiltonian dynamics of an auxiliary noise-free system. The solution also gives the switching barrier. The barrier can be found explicitly close to parameter values where the number of stable states of the system changes and the dynamics is controlled by a slow variable. The scaling of the barrier height depends on the type of the corresponding bifurcation. We show that, both for birth-death and for Gaussian noise driven systems, the presence of even weak non-Gaussian noise can strongly modify the switching rate. The effect is described in a simple explicit form [2,3]. Weak deviations of the noise statistics from Gaussian can be sensitively detected using balanced dynamical bridge, where this deviation makes the populations of coexisting stable states different from each other; a realization of such a bridge will be discussed. We will also discuss the sharp

  6. A high-transmission liquid-crystal Fabry-Perot infrared filter for electrically tunable spectral imaging detection

    Science.gov (United States)

    Liu, Zhonglun; Xin, Zhaowei; Long, Huabao; Wei, Dong; Dai, Wanwan; Zhang, Xinyu; Wang, Haiwei; Xie, Changsheng

    2018-02-01

    Previous studies have presented the usefulness of typical liquid-crystal Fabry-Perot (LC-FP) infrared filters for spectral imaging detection. Yet, their infrared transmission performances still remain to improve or even rise. In this paper, we propose a new type of electrically tunable LC-FP infrared filter to solve the problem above. The key component of the device is a FP resonant cavity composed of two parallel plane mirrors, in which the zinc selenide (ZnSe) materials with a very high transmittance in the mid-long-wavelength infrared regions are used as the electrode substrates and a layer of nano-aluminum (Al) film, which is directly contacted with liquid-crystal materials, is chosen to make high reflective mirrors as well as the electrodes. Particularly, it should be noted that the directional layer made up of ployimide (PI) used previously is removed. The experiment results indicate that the filter can reduce the absorption of infrared wave remarkably, and thus highlight a road to effectively improve the infrared transmittance ability.

  7. High-performance liquid chromatography with fluorescence detection for the rapid analysis of pheophytins and pyropheophytins in virgin olive oil.

    Science.gov (United States)

    Li, Xueqi; Woodman, Michael; Wang, Selina C

    2015-08-01

    Pheophytins and pyropheophytin are degradation products of chlorophyll pigments, and their ratios can be used as a sensitive indicator of stress during the manufacturing and storage of olive oil. They increase over time depending on the storage condition and if the oil is exposed to heat treatments during the refining process. The traditional analysis method includes solvent- and time-consuming steps of solid-phase extraction followed by analysis by high-performance liquid chromatography with ultraviolet detection. We developed an improved dilute/fluorescence method where multi-step sample preparation was replaced by a simple isopropanol dilution before the high-performance liquid chromatography injection. A quaternary solvent gradient method was used to include a fourth strong solvent wash on a quaternary gradient pump, which avoided the need to premix any solvents and greatly reduced the oil residues on the column from previous analysis. This new method not only reduces analysis cost and time but shows reliability, repeatability, and improved sensitivity, especially important for low-level samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Liquid Microjunction Surface Sampling Probe Electrospray Mass Spectrometry for Detection of Drugs and Metabolites in Thin Tissue Sections

    Energy Technology Data Exchange (ETDEWEB)

    Van Berkel, Gary J [ORNL; Kertesz, Vilmos [ORNL; Koeplinger, Kenneth A. [Merck Research Laboratories; Vavek, Marissa [Merck Research Laboratories; Kong, Ah-Ng Tony [Rutgers University

    2008-01-01

    A self-aspirating, liquid micro-junction surface sampling probe/electrospray emitter mass spectrometry system was demonstrated for use in the direct analysis of spotted and dosed drugs and their metabolites in thin tissue sections. Proof-of-principle sampling and analysis directly from tissue without the need for sample preparation was demonstrated first by raster scanning a region on a section of rat liver onto which reserpine was spotted. The mass spectral signal from selected reaction monitoring was used to develop a chemical image of the spotted drug on the tissue. The probe was also used to selectively spot sample areas of sagittal whole mouse body tissue sections that had been dosed orally (90 mg/kg) with R,S-sulforaphane 3 hrs prior to sacrifice. Sulforaphane and its glutathione and N-acetyl cysteine conjugates were monitored with selected reaction monitoring and detected in the stomach and various other tissues from the dosed mouse. No signal for these species was observed in the tissue from a control mouse. The same dosed tissue section was used to illustrate the possibility of obtaining a line scan across the whole body section. In total these results illustrate the potential for rapid screening of the distribution of drugs and metabolites in tissue sections with the micro-liquid junction surface sampling probe/electrospray mass spectrometry approach.

  9. LC-IMS-MS Feature Finder: detecting multidimensional liquid chromatography, ion mobility and mass spectrometry features in complex datasets.

    Science.gov (United States)

    Crowell, Kevin L; Slysz, Gordon W; Baker, Erin S; LaMarche, Brian L; Monroe, Matthew E; Ibrahim, Yehia M; Payne, Samuel H; Anderson, Gordon A; Smith, Richard D

    2013-11-01

    The addition of ion mobility spectrometry to liquid chromatography-mass spectrometry experiments requires new, or updated, software tools to facilitate data processing. We introduce a command line software application LC-IMS-MS Feature Finder that searches for molecular ion signatures in multidimensional liquid chromatography-ion mobility spectrometry-mass spectrometry (LC-IMS-MS) data by clustering deisotoped peaks with similar monoisotopic mass, charge state, LC elution time and ion mobility drift time values. The software application includes an algorithm for detecting and quantifying co-eluting chemical species, including species that exist in multiple conformations that may have been separated in the IMS dimension. LC-IMS-MS Feature Finder is available as a command-line tool for download at http://omics.pnl.gov/software/LC-IMS-MS_Feature_Finder.php. The Microsoft.NET Framework 4.0 is required to run the software. All other dependencies are included with the software package. Usage of this software is limited to non-profit research to use (see README). rds@pnnl.gov. Supplementary data are available at Bioinformatics online.

  10. Determination of Cinchona alkaloids and Vitamin B6 by high-performance liquid chromatography with fluorescence detection

    International Nuclear Information System (INIS)

    Gatti, R.; Gioia, M.G.; Cavrini, V.

    2004-01-01

    A simple and specific method has been developed for the simultaneous determination of the four major Cinchona alkaloids and their dihydroderivatives and pyridoxine hydrochloride (Vitamin B 6 ) by high-performance liquid chromatography (HPLC) with fluorescence detection (λ em =420 nm with λ ex =330 nm). The chromatographic separation was performed on a Phenomenex Prodigy ODS column (5 μm, 250 mmx3.2 mm i.d.), recommended for basic compounds, under isocratic reversed-phase conditions. The method allowed a good peak shape and an effective resolution of the tested compounds. The extraction of alkaloids from the Cinchona succirubra bark was carried out in mild and fast conditions (ambient temperature, 20 min) by ultrasonication. The procedure showed to be advantageous respect to a reference method, which involved Soxhlet extraction. The results were compared statistically by means of the Student's t-test and the variance ratio F-test; no significant difference was found. The method was reproducible (relative standard deviations in the range of 1.0-5.0% for the different alkaloids) and gave quantitative recovery of alkaloids added to bark samples (97.8-105%). For additional informations a photoreactor was arranged between the analytical column and the detector and the online post-column photochemical conversion (irradiation=254 nm) was investigated. Vitamin B 6 was shown to be highly photosensitive, giving significantly different fluorescence spectra with and without UV irradiation. The proposed method was successfully applied to the quality control of Cinchona bark, liquid extract and cosmetics

  11. Determination of benzimidazole residues and their metabolites in raw milk using high performance liquid chromatography-diode array detection

    Directory of Open Access Journals (Sweden)

    Marija Denžić Lugomer

    2017-01-01

    Full Text Available A new analytical method using high performance liquid chromatography-diode array detector (HPLC-DAD was developed for the analysis of 18 benzimidazoles and their metabolites in milk. Samples were extracted with acetonitrile and n-hexane and purified by polymer cation exchange (PCX solid phase extraction cartridges. LC separation was performed on Xbridge C18 with gradient elution using acetonitrile and ammonium acetate buffer. The DAD detection was set at 298, 312, 254 and 290 nm. The method was validated according to the criteria of Commission Decision 2002/657/EC. The following validation parameters were set: accuracy (expressed as recovery 31.7-137.6 %, limit of decision (CCα 6.0-120.6 μg kg-1, detection capability (CCβ 6.1-120.8 μg kg-1, limit of detection (LOD 1-4 μg kg-1, limit of quantification (LOQ 4-18 μg kg-1, precision as CV 7.0-22.5 %, withinlaboratory reproducibility expressed as CV 8.8-30.6 %. Finally, the developed method was applied to the analysis of collected milk samples. A total of 50 milk samples was analysed for benzimidazole residues. All obtained concentrations for all compounds were below the LOQ values.

  12. Determination of phenolic compounds using high-performance liquid chromatography with Ce{sup 4+}-Tween 20 chemiluminescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Cui Hua; Zhou Jian; Xu Feng; Lai Chunze; Wan Guohui

    2004-05-31

    A novel method for the simultaneous determination of phenolic compounds such as salicylic acid, resorcinol, phloroglucinol, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, and m-nitrophenol by high-performance liquid chromatography (HPLC) coupled with chemiluminescence (CL) detection was developed. The procedure was based on the chemiluminescent enhancement by phenolic compounds of the cerium(IV)-Tween 20 system in a sulfuric acid medium. The separation was carried out with an isocratic elution or with a gradient elution using a mixture of methanol and 1.5% acetic acid. For six phenolic compounds, the detection limits (3{sigma}) were in the range 1.40-5.02 ng/ml and the relative standard deviations (n=11) for the determination of 0.1 {mu}g/ml compounds were in the range 1.9-2.9%. The CL reaction was well compatible with the mobile phase of HPLC, no baseline drift often occurred in HPLC-CL detection was observed with a gradient elution. The method has been successfully applied to the determination of salicylic acid and resorcinol in Dermatitis Clear Tincture and p-hydroxybenzoic acid in apple juices.

  13. [Detection of streptomycin resistance in Mycobacterium tuberculosis clinical isolates by denaturing high-performance liquid chromatography and DNA sequencing].

    Science.gov (United States)

    Shi, Rui-ru; Zhang, Jian-yuan; Yuan, Xue-qin; Sun, Zhao-gang; Li, Chuan-you

    2008-05-27

    To determine the rpsL and rrs gene mutation in Mycobacterium tuberculosis (M. tuberculosis) and compare the consistency between the results of denaturing high-performance liquid chromatography (DHPLC) and those of DNA sequencing. The values of streptomycin minimum inhibitory concentration (MIC) against 215 M. tuberculosis clinical isolates, 115 being streptomycin-resistant and 100 being susceptible by a routine proportional method, were tested by DHPLC. DNA sequencing was conducted to detect the rpsL and rrs mutation. 98 of the 115 streptomycin-resistant isolates (85.2%) harbored rpsL and/or rrs mutation, 76.5% of which being rpsL mutation (88/115). There was no significant correlation between the MIC values and mutation types. No mutation was found in all the susceptible isolates. There was a complete consistency between the DHPLC results and those of DNA sequencing. DHPLC can be regarded as a useful and powerful tool to detect the streptomycin resistance detection in M. tuberculosis.

  14. Contemporary Sample Preparation Methods for the Detection of Ignitable Liquids in Suspect Arson Cases.

    Science.gov (United States)

    Bertsch, W; Ren, Q

    1999-12-01

    The isolation of ignitable liquid components, usually petroleum-based distillates from fire debris, is an important step in deciding whether a fire is of natural or incendiary origin. Steady progress has been made to develop sample preparation methods capable of enriching target analytes in high yield and within a short period of time. Heated headspace enrichment methods are currently most widely used. There are several variations of this basic technique. Carbon-based adsorbents are most popular. They come in different forms and shapes, including a flat sheet of polymer, impregnated with carbon particles. The analyst cuts a small strip from this sheet and suspends it in the heated headspace above the debris sample. The volatiles adsorb onto the carbon surface, eventually reaching an equilibrium condition. The process is usually carried out in an oven. This convenient method, called the static method, has largely replaced the dynamic method, which uses a granular charcoal adsorbent. In the latter, the heated headspace is drawn over a short trap packed with charcoal, using a source of vacuum such as a pump or pushed along using pressurized nitrogen. The headspace volatiles in both the static and dynamic method are recovered by elution with a solvent, usually carbon disulfide. Recently, a promising variation of the static headspace method has been introduced. It is based on the use of a tiny amount of a polysiloxane polymer which has been coated onto the tip of a thin silica fiber. The fiber can be retracted into a syringe-type needle and the adsorbed headspace vapor can be conveniently introduced into the heated injector port of a gas chromatograph. No solvent is required. This technique, abbreviated SPME (for solid-phase microextraction) has many attractive advantages but it is not without some problems. Low boiling range accelerants, including water-soluble polar substances such as ethanol, are poorly retained on methylsiloxane type polymers. The recent

  15. Method of detecting stacks with leaky fuel elements in liquid-metal-cooled reactor and apparatus for effecting same

    International Nuclear Information System (INIS)

    Aristarkhov, N.N.; Efimov, I.A.; Zaistev, B.I.; Peters, I.G.; Tymosh, B.S.

    1976-01-01

    Described is a method of detecting stacks with leaky fuel elements in a liquid-metal-cooled reactor, consisting in that prior to withdrawing a coolant sample, gas is accumulated in the coolant of the stack being controlled, the reactor being shut down, separated from the sample by means of an inert carrier gas, and the radioactivity of the separated gas is measured. An apparatus for carrying out said method comprises a sampler in the form of a tube parallel to the reactor axis in the hole of a rotating plug and adapted to move along the reactor axis. Made in the top portion of the tube are holes for the introduction of the inert carrier gas and the removal thereof together with the gases evolved from the coolant, while the bottom portion of the tube is provided with a sealing member

  16. Applying Ant Colony Algorithm and Neural Network Model to Color Deviation Defect Detection in Liquid Crystal Displays

    Directory of Open Access Journals (Sweden)

    Hong-Dar Lin

    2005-06-01

    Full Text Available Thin Film Transistor Liquid Crystal Display (TFT-LCD has excellent properties such as lower voltage to start and less occupied space if comparing with traditional Cathode-Ray Tube (CRT. But screen flaw points and display color deviation defects on image display exist in TFT-LCD products. This research proposes a new automated visual inspection method to solve the problems. We first use multivariate Hotelling T2 statistic for integrating coordinates of color models to construct a T2 energy diagram for inspecting defects and controlling patterns in TFT-LCD display images. An Ant Colony based approach that integrates computer vision techniques is developed to detect the flaw point defects. Then, Back Propagation Network (BPN model is proposed to inspect small deviation defects of the LCD display colors. Experimental results show the proposed system can provide good effects and practicality.

  17. Detection of liquid petroleum gas using mixed nanosized tungsten oxide-based thick-film semiconductor sensor.

    Science.gov (United States)

    Chaudhari, G N; Bende, A M; Bodade, A B; Patil, S S; Manorama, S V

    2006-03-15

    The thick-film semiconductor sensor for liquid petroleum gas (LPG) detection was fabricated using a mixed WO(3)-based sensor. We present the characterization of both their structural properties by means of XRD measurements and the electrical characteristics by using gas-sensing properties. The sensing characteristics such as sensitivity, working range, cross-sensitivity and response time were studied by using nanosized WO(3)-based mixed with different metal oxides (SnO(2), TiO(2) and In(2)O(3)) and doped with noble metals (Au, Pd and Pt). The WO(3)-based mixed with 5 wt.% In(2)O(3) and 0.5 wt.% Pd showed the higher sensing characteristic at low concentration of LPG sensor at an operating temperature 225 degrees C.

  18. Determination of paraffins in food simulants and packaging materials by liquid chromatography with evaporative mass detection and identification of paraffin type by liquid chromatography/gas chromatography and fourier transform infrared spectroscopy

    NARCIS (Netherlands)

    Simal-Gándara, J.; Sarria-Vidal, M.; Rijk, M.A.H.

    2000-01-01

    A liquid chromatographic method with evaporative mass detection (EMD) is described for the determination of paraffins in food contact materials that do not contain polyolefin oligomers, or paraffins migrating from these materials into fatty food simulants or certain simple foods. A normal-phase

  19. Effect of Ionic Liquid on the Determination of Aromatic Amines as Contaminants in Hair Dyes by Liquid Chromatography Coupled to Electrochemical Detection

    Directory of Open Access Journals (Sweden)

    Maria Valnice Boldrin Zanoni

    2012-07-01

    Full Text Available The room temperature ionic liquid (IL 1-butyl-3-methylimidazolium bis-(trifluorometanesulfonylimide BMIm[NTf2] was used as a novel medium for improvement of separation and quantization of 16 aromatic amines typically present as contaminants in consumer products and detected by HPLC coupled to an electrochemical detector. The aromatic amines, namely 4,4'-diaminodiphenylmethane, 4-chloroaniline, 2-methoxy-5-methyl-aniline, 3,3'-dimethylbenzidine, 2,4-diaminotoluidine, 2-chloro-4-nitroaniline, 4,4'-oxydianiline, aniline, 3,3'-dichlorobenzidine, benzidine, 4-aminobiphenyl, o-dianisidine, o-anisidine, o-toluidine, 4,4'-methylene-bis-2-chloroaniline and 2-naphthyl-amine are oxidized in methanol/BMIm[NTf2] at a potential around +0.68V to +0.93V vs. Ag/AgCl at a glassy carbon electrode, which is the base for their determination by HPLC/ED. Using the optimized conditions of methanol/BMIm[NTf2] 70:30 (v/v as mobile phase, flow-rate of 0.8 mL·min−1, column CLC-ODS, Eap = +1.0 V and T = 40 °C analytical curves were constructed for each of the tested amines. Good linearity was obtained in the concentration range of 1.09 mg·L−1 to 217 mg·L−1, with excellent correlation coefficients. The limits of detection reached 0.021 mg·L−1 to 0.246 mg·L−1 and good relative standard deviations (RSD, n = 3 were obtained from the measurements. Satisfactory recovery for each aromatic amine was achieved, ranging from 95 to 103%. The developed method was successfully applied to determine six aromatic amines present as contaminants in commercial hair dye samples.

  20. Love-wave bacteria-based sensor for the detection of heavy metal toxicity in liquid medium.

    Science.gov (United States)

    Gammoudi, I; Tarbague, H; Othmane, A; Moynet, D; Rebière, D; Kalfat, R; Dejous, C

    2010-12-15

    The present work deals with the development of a Love-wave bacteria-based sensor platform for the detection of heavy metals in liquid medium. The acoustic delay-line is inserted in an oscillation loop in order to record the resonance frequency in real-time. A Polydimethylsiloxane (PDMS) chip with a liquid chamber is maintained by pressure above the acoustic wave propagation path. Bacteria (Escherichia coli) were fixed as bioreceptors onto the sensitive surface of the sensor coated with a polyelectrolyte (PE) multilayer using a simple and efficient layer-by-layer (LbL) electrostatic self-assembly procedure. Poly(allylamine hydrochloride) (PAH cation) and poly(styrene sulfonate) (PSS anion) were alternatively deposited so that the strong attraction between oppositely charged polyelectrolytes resulted in the formation of a (PAH-PSS)(n)-PAH molecular multilayer. The real-time characterization of PE multilayer and bacteria deposition is based on the measurement of the resonance frequency perturbation due to mass loading during material deposition. Real-time response to various concentrations of cadmium (Cd(2+)) and mercury (Hg(2+)) has been investigated. A detection limit as low as 10(-12) mol/l has been achieved, above which the frequency increases gradually up to 10(-3) mol/l, after a delay of 60 s subsequent to their introduction onto bacterial cell-based biosensors. Beyond a 10(-3) mol/l a steep drop in frequency was observed. This response has been attributed to changes in viscoelastic properties, related to modifications in bacteria metabolism. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Simultaneous detection of water-soluble vitamins using the High Performance Liquid Chromatography (HPLC - a review

    Directory of Open Access Journals (Sweden)

    Rosemond Godbless Dadzie

    2014-01-01

    Full Text Available The water-soluble vitamins (WSV: ascorbic acid (vitamin C, thiamine (B1, riboflavin (B2, niacin (B3, panthothenic acid (B5, pyridoxine, and pyridoxal (B6, folic acid (B9, biotin(B8 , and B12 are very essential in the diet of humankind. As a result of ever increasing pressures from both consumers and legal enforcers, to specify accurately nutritive compositions of WSV that are present in food materials, many researchers have attempted to fill this niche through the provision of highly sensitive and rapid high performance liquid chromatography (HPLC procedures. In view of the health benefits of WSV, a replete of HPLC methods have been developed for simultaneous determination of their contents in nature and fortified food samples, nutritional supplements, as well as blood plasmas. The rate of losses of these vitamins during food processing and analysis, in addition to their transient dynamics, presents complexities in developing a highly sensitive HPLC procedure for their simultaneous separations and assays. This review critically assesses the different HPLC procedures developed by researchers and available in the open literature for simultaneous determination of water-soluble vitamins (WSV in dried tropical fruits materials. The study revealed that not a single chromatographic run developed by researchers can simultaneously elute all the WSV at a time. However, the HPLC procedures that are capable of determining all the WSV were coupled with electrospray ionization mass spectroscopy (ESI-MS, thus making the set-up expensive.

  2. Hazards of Secondary Bromadiolone Intoxications Evaluated using High-performance Liquid Chromatography with Electrochemical Detection

    Directory of Open Access Journals (Sweden)

    René Kizek

    2007-07-01

    Full Text Available This study reported on the possibility of intoxications of non-target wild animalsassociated with use of bromadiolone as the active component of rodenticides withanticoagulation effects. A laboratory test was done with earthworms were exposed tobromadiolone-containing granules under the conditions specified in the modified OECD207 guideline. No mortality of earthworms was observed during the fourteen days longexposure. When the earthworms from the above test became a part of the diet of commonvoles in the following experiment, no mortality of consumers was observed too. However,electrochemical analysis revealed higher levels of bromadiolone in tissues fromearthworms as well as common voles compared to control animals. There were determinedcomparable levels of bromadiolone in the liver tissue of common voles after primary(2.34±0.10 μg/g and secondary (2.20±0.53 μg/g intoxication. Therefore, the risk ofsecondary intoxication of small mammalian species feeding on bromadiolone-containing earthworms is the same as of primary intoxication through baited granules. Bromadiolone bio-accumulation in the food chain was monitored using the newly developed analytical procedure based on the use of a liquid chromatography coupled with electrochemical detector (HPLC-ED. The HPLC-ED method allowed to determine the levels of bromadiolone in biological samples and is therefore suitable for examining the environmental hazards of this substance.

  3. Evaluation of a liquid urease test (LUT) for detection of Helicobacter pylori.

    Science.gov (United States)

    Montes, H; Salmen, S; Dolfo, W; Sotolongo, Asmiria; Petrosino, Pierina; Donis, J; Berrueta, Lisbeth

    2003-01-01

    The aim of our study was to develop a rapid diagnostic urease test to demonstrate the presence of Helicobacter pylori in the Endoscopy room. 200 consecutive patients referred to gastroscopy for different indications, were included in this study. One antral biopsy sample was obtained to be immersed in our test. The same sample was used for histological evaluation, considered to be the gold standard method for diagnose of Helicobacter pylori infection. 135 patients (67.5%) were found positives and 65 patients (32.5%) were negatives in our test. 128 patients (64%) showed Helicobacter pylori on histological examination. Our test showed a sensitivity of 91%, specificity of 88.1%, and positive and negative predictive values of 95% and 80% respectively. A remarkable correlation between density of Helicobacter pylori and reading time was also observed, where a high density of the bacteria reduced the reaction time in this liquid test. Furthermore, an overall accuracy of 90% was shown, which is comparable with other available commercial tests. LUT is easy to handle, cost effective and fast, with a high positive predictive value.

  4. Liquid Chromatography-Mass Spectrometry Interface for Detection of Extraterrestrial Organics

    Science.gov (United States)

    Southard, Adrian E.; Getty, Stephanie A.; Balvin, Manuel; Cook, Jamie E.; Espiritu, Ana Mellina; Kotecki, Carl; Towner, Deborah W.; Dworkin, J. P.; Glavin, Daniel P.; Mahaffy, Paul R.; hide

    2014-01-01

    The OASIS (Organics Analyzer for Sampling Icy surfaces) microchip enables electrospray or thermospray of analyte for subsequent analysis by the OASIS time-of-flight mass spectrometer. Electrospray of buffer solution containing the nucleobase adenine was performed using the microchip and detected by a commercial time-of-flight mass spectrometer. Future testing of thermospray and electrospray capability will be performed using a test fixture and vacuum chamber developed especially for optimization of ion spray at atmosphere and in low pressure environments.

  5. Controller Architectures for Switching

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2009-01-01

    This paper investigate different controller architectures in connection with controller switching. The controller switching is derived by using the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization. A number of different architectures for the implementation of the YJBK parameterization...... are described and applied in connection with controller switching. An architecture that does not include inversion of the coprime factors is introduced. This architecture will make controller switching particular simple....

  6. Ion chromatography with the indirect ultraviolet detection of alkali metal ions and ammonium using imidazolium ionic liquid as ultraviolet absorption reagent and eluent.

    Science.gov (United States)

    Liu, Yong-Qiang; Yu, Hong

    2016-08-01

    Indirect ultraviolet detection was conducted in ultraviolet-absorption-agent-added mobile phase to complete the detection of the absence of ultraviolet absorption functional group in analytes. Compared with precolumn derivatization or postcolumn derivatization, this method can be widely used, has the advantages of simple operation and good linear relationship. Chromatographic separation of Li(+) , Na(+) , K(+) , and NH4 (+) was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid/organic solvent as the mobile phase, in which imidazolium ionic liquids acted as ultraviolet absorption reagent and eluting agent. The retention behaviors of four kinds of cations are discussed, and the mechanism of separation and detection are described. The main factors influencing the separation and detection were the background ultraviolet absorption reagent and the concentration of hydrogen ion in the ion chromatography-indirect ultraviolet detection. The successful separation and detection of Li(+) , Na(+) , K(+) , and NH4 (+) within 13 min was achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.02, 0.11, 0.30, and 0.06 mg/L, respectively. A new separation and analysis method of alkali metal ions and ammonium by ion chromatography with indirect ultraviolet detection method was developed, and the application range of ionic liquid was expanded. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Bio-analytical method development and validation of Rasagiline by high performance liquid chromatography tandem mass spectrometry detection and its application to pharmacokinetic study

    OpenAIRE

    Ravi Kumar Konda; Babu Rao Chandu; B.R. Challa; Chandrasekhar B. Kothapalli

    2012-01-01

    The most suitable bio-analytical method based on liquidâliquid extraction has been developed and validated for quantification of Rasagiline in human plasma. Rasagiline-13C3 mesylate was used as an internal standard for Rasagiline. Zorbax Eclipse Plus C18 (2.1 mmÃ50 mm, 3.5 μm) column provided chromatographic separation of analyte followed by detection with mass spectrometry. The method involved simple isocratic chromatographic condition and mass spectrometric detection in the positive ion...

  8. An evaluation of clinical performance of FTA cards for HPV 16/18 detection using cobas 4800 HPV Test compared to dry swab and liquid medium.

    Science.gov (United States)

    Dong, Li; Lin, Chunqing; Li, Li; Wang, Margaret; Cui, Jianfeng; Feng, Ruimei; Liu, Bin; Wu, Zeni; Lian, Jia; Liao, Guangdong; Chen, Wen; Qiao, Youlin

    2017-09-01

    Effective dry storage and transport media as an alternative to conventional liquid-based medium would facilitate the accessibility of women in the low-resource settings to human papillomavirus (HPV)- based cervical cancer screening. To evaluate analytical and clinical performance of indicating FTA™ Elute Cartridge (FTA card) for the detection of HPV16/18 and cervical precancerous lesions and cancer compared to dry swab and liquid medium. Ninety patients with abnormal cytology and/or HPV infection were included for analysis. Three specimens of cervical exfoliated cells from each woman were randomly collected by FTA card, dry swab or liquid-based medium prior to colposcopy examination. The subsequent HPV DNA tests were performed on cobas 4800 HPV platform. High-risk HPV (hrHPV) positivity rate was 63.3%, 62.2% and 65.6% for samples collected by FTA card, dry swab and liquid medium, respectively. The overall agreements and kappa values for the detection of hrHPV, HPV 16 and HPV 18 between FTA card and liquid-based medium were 88.9% (κ=0.76), 97.8% (κ=0.94) and 100% (κ=1.0),respectively; between FTA card and dry swab were 92.1% (κ=0.83), 94.5% (κ=0.87) and 100% (κ=1.0), respectively. The performances of hrHPV tested by FTA card, dry swab, and liquid-based medium for detecting CIN2+ were comparable in terms of the sensitivity and specificity. The specificity of detection of CIN2+ by HPV16/18 increased by approximately 40% compared to hrHPV for any medium albeit at cost of a moderate loss of sensitivity. Dry medium might offer an alternative to conventional liquid-based medium in the HPV-based cervical cancer screening program especially in low-resource settings but still needs further evaluation. Copyright © 2017. Published by Elsevier B.V.

  9. Novel algorithm for simultaneous component detection and pseudo-molecular ion characterization in liquid chromatography–mass spectrometry

    International Nuclear Information System (INIS)

    Zhang, Yufeng; Wang, Xiaoan; Wo, Siukwan; Ho, Hingman; Han, Quanbin; Fan, Xiaohui; Zuo, Zhong

    2015-01-01

    Highlights: • Novel stepwise component detection algorithm (SCDA) for LC–MS datasets. • New isotopic distribution and adduct-ion models for mass spectra. • Automatic component classification based on adduct-ion and isotopic distributions. - Abstract: Resolving components and determining their pseudo-molecular ions (PMIs) are crucial steps in identifying complex herbal mixtures by liquid chromatography–mass spectrometry. To tackle such labor-intensive steps, we present here a novel algorithm for simultaneous detection of components and their PMIs. Our method consists of three steps: (1) obtaining a simplified dataset containing only mono-isotopic masses by removal of background noise and isotopic cluster ions based on the isotopic distribution model derived from all the reported natural compounds in dictionary of natural products; (2) stepwise resolving and removing all features of the highest abundant component from current simplified dataset and calculating PMI of each component according to an adduct-ion model, in which all non-fragment ions in a mass spectrum are considered as PMI plus one or several neutral species; (3) visual classification of detected components by principal component analysis (PCA) to exclude possible non-natural compounds (such as pharmaceutical excipients). This algorithm has been successfully applied to a standard mixture and three herbal extract/preparations. It indicated that our algorithm could detect components’ features as a whole and report their PMI with an accuracy of more than 98%. Furthermore, components originated from excipients/contaminants could be easily separated from those natural components in the bi-plots of PCA

  10. Determination of phenolic compounds and hydroxymethylfurfural in meads using high performance liquid chromatography with coulometric-array and UV detection.

    Science.gov (United States)

    Kahoun, David; Rezková, Sona; Veskrnová, Katerina; Královský, Josef; Holcapek, Michal

    2008-08-15

    The objective of this study was the determination of 25 phenolic compounds in different mead samples (honeywines) using high performance liquid chromatography (HPLC) with coulometric-array detection and in case of hydroxymethylfurfural with UV detection. Our method was optimized in respect to both the separation selectivity of individual phenolic compounds and the maximum sensitivity with the electrochemical detection. The method development included the optimization of mobile phase composition, the pH value, conditions of the gradient elution and the flow rate using a window-diagram approach. The developed method was used for the determination of limits of detection and limits of quantitation for individual compounds. The linearity of calibration curves, accuracy and precision (intra- and inter-day) at three concentration levels (low, middle and high concentration range) were verified. Mead samples were diluted with the mobile phase at 1:1 to 1:50 ratio depending on the concentration and filtered through a PTFE filter without any other sample pre-treatment. Phenolic compounds concentration was determined in 50 real samples of meads and correlated with meads composition and hydroxymethylfurfural concentration. The most frequently occurred compounds were protocatechuic acid and vanillic acid (both of them were present in 98% samples), the least occurred compounds were (+)-catechin (10% samples) and sinapic acid (12% samples). Vanillin and ethylvanillin, which are used as artificial additives for the taste improvement, were found in 60% and 42% samples, respectively. Hydroxymethylfurfural concentration, as an indicator of honey quality, was in the range from 2.47 to 158 mg/L. Our method is applicable for the determination of 25 phenolic compounds in mead, honey and related natural samples.

  11. Novel algorithm for simultaneous component detection and pseudo-molecular ion characterization in liquid chromatography–mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yufeng; Wang, Xiaoan; Wo, Siukwan [School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China); Ho, Hingman; Han, Quanbin [School of Chinese Medicine, Hong Kong Baptist University, 7 Baptist University Road, Kowloon Tong, Hong Kong (China); Fan, Xiaohui [College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058 (China); Zuo, Zhong, E-mail: joanzuo@cuhk.edu.hk [School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China)

    2015-01-01

    Highlights: • Novel stepwise component detection algorithm (SCDA) for LC–MS datasets. • New isotopic distribution and adduct-ion models for mass spectra. • Automatic component classification based on adduct-ion and isotopic distributions. - Abstract: Resolving components and determining their pseudo-molecular ions (PMIs) are crucial steps in identifying complex herbal mixtures by liquid chromatography–mass spectrometry. To tackle such labor-intensive steps, we present here a novel algorithm for simultaneous detection of components and their PMIs. Our method consists of three steps: (1) obtaining a simplified dataset containing only mono-isotopic masses by removal of background noise and isotopic cluster ions based on the isotopic distribution model derived from all the reported natural compounds in dictionary of natural products; (2) stepwise resolving and removing all features of the highest abundant component from current simplified dataset and calculating PMI of each component according to an adduct-ion model, in which all non-fragment ions in a mass spectrum are considered as PMI plus one or several neutral species; (3) visual classification of detected components by principal component analysis (PCA) to exclude possible non-natural compounds (such as pharmaceutical excipients). This algorithm has been successfully applied to a standard mixture and three herbal extract/preparations. It indicated that our algorithm could detect components’ features as a whole and report their PMI with an accuracy of more than 98%. Furthermore, components originated from excipients/contaminants could be easily separated from those natural components in the bi-plots of PCA.

  12. Detection of chloramphenicol residue in bovine meat using Liquid Chromatography Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Widiastuti R

    2014-03-01

    Full Text Available Chloramphenicol (CAP is a broad spectrum antibiotic that has been banned in many countries due to its serius side effect to human. Detection of CAP residue in food has been determined to a minimum required performance limit (MRPL of 0.3 ng/g. The purpose of this research was to conduct the analysis of CAP residue in bovine meat by using LCMS and to study the presence of CAP residue in marketed bovine meat samples. LC separation was done on a Shimpack column C18 with ammonium acetate 10 mM/water as mobile phase, and ESI-MS analysis in negative ion mode. The coefficient of determination, R2 = 0.9981 at concentration of 0.125, 0.25, 0.63, 1,00 and 2.00 ng/g. Recovery at three fortification levels (0.25, 0.50 and 1.00 ng/g was in the range 77.5, 97.3 and 83.4%. The decision limit and the detection capability were 0.15 ng/g and 0.17 ng/g respectively. Analysis results of 52 marketed samples showed that CAP residue were detected in 9 samples in the concentration range of 0.14 to 2.70 ng/g and 6 among those positive samples were above the MRPL value. Therefore, it is important to increase the awareness and also to monitor regularly CAP residues in food originated from animal to provide safe food for the consumers.

  13. Studies of metal-biomolecule systems in liquids with beta-detected NMR

    CERN Document Server

    Walczak, Michal

    2017-01-01

    My internship took place within a small research team funded via the European Research Council (ERC Starting Grant: Beta-Drop NMR) at ISOLDE. It was devoted to laser spin-polarization and beta-detected NMR techniques and their future applications in chemistry and biology. I was involved in the design and tests of the beta-NMR spectrometer which will be used in the upcoming experiments. In this way I have been exposed to many topics in physics (atomic and nuclear physics), experimental techniques (vacuum technology, lasers, beta detectors, electronics, DAQ software), as well as chemistry and biology (NMR on metal ions, metal ion binding to biomolecules, quantum chemistry calculations).

  14. Sensitive determination of zearalenone and alpha-zearalenol in barley and Job's-tears by liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Tanaka, T; Teshima, R; Ikebuchi, H; Sawada, J; Terao, T; Ichinoe, M

    1993-01-01

    A sensitive and reliable method for liquid chromatographic (LC) determination of zearalenone and alpha-zearalenol in barley and Job's-tears was investigated. The method by which these toxins were determined involves addition of an internal standard (zearalenone 6'-oxime) to barley and Job's-tears samples. Extracts from grain samples were cleaned up by passage through chromatography on piperidinohydroxypropyl Sephadex LH-20 as a lipophilic gel. Individual toxins were resolved by LC on a reversed-phase (ODS) column with fluorescence detection. The detection limit is estimated to be 0.2 ng for zearalenone and alpha-zearalenol standards. Known amounts of zearalenone and alpha-zearalenol (25-1250 ng) were added to a barley sample (5 g). Average recoveries for alpha-zearalenol and zearalenone, respectively, ranged from 96 to 102% (mean CV, 3.6%) and from 96 to 103% (mean CV, 3.3%). This method is applicable to determination of alpha-zearalenol and zearalenone in barley and Job's tears with satisfactory sensitivity and accuracy.

  15. Detection of peroxyl radicals from polluted air by free radical reaction combined with liquid chromatography signal amplification technique.

    Science.gov (United States)

    Wang, Guoying; Jia, Shiming; Niu, Xiuli; Liu, Yanrong; Tian, Haoqi; Chen, Xuefu; Shi, Gaofeng

    2018-01-22

    Free radicals play an important role in the oxidizing power of polluted air, the development of aging-related diseases, the formation of ozone, and the production of secondary particulate matter. The high variability of peroxyl radical concentration has prevented the detection of possible trends or distributions in the concentration of free radicals. We present a new method, free radical reaction combined with liquid chromatography photodiode array detection, for identifying and quantifying peroxyl radicals in polluted air. Functionalized graphene was used for loading peroxyl radicals and reactive molecules in air sampling system, which can facilitate reaction kinetics (charge transfers) between peroxyl radicals and reaction molecules. Separation was performed with and without a preliminary exposure of the polluted air sample to reactive molecule(s) system. The integral chromatographic peak areas before and after air sampling are used to quantify the atmospheric peroxyl radicals in polluted air. The utility of the new technique was tested with measurements carried out in the field. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Improved sample treatment for the determination of insoluble soap in sewage sludge samples by liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Cantarero, Samuel; Zafra-Gómez, A; Ballesteros, O; Navalón, A; Vílchez, J L; Crovetto, G; Verge, C; de Ferrer, J A

    2010-09-15

    A new selective and sensitive method for the determination of insoluble fatty acid salts (soap) in sewage sludge samples is proposed. The method involves a clean up of sample with petroleum ether, the conversion of calcium and magnesium insoluble salts into soluble potassium salts, potassium salts extraction with methanol, and a derivatization procedure previous to the liquid chromatography with fluorescence detection (LC-FLD) analysis. Three different extraction techniques (Soxhlet, microwave-assisted extraction and ultrasounds) were compared and microwave-assisted extraction (MAE) was selected as appropriate for our purpose. This allowed to reduce the extraction time and solvent waste (50 mL of methanol in contrast with 250 mL for Soxhlet procedure). The absence of matrix effect was demonstrated with two standards (C(13:0) and C(17:0)) that are not commercials and neither of them has been detected in sewage sludge samples. Therefore, it was possible to evaluate the matrix effect since both standards have similar environmental behaviour (adsorption and precipitation) to commercial soaps (C(10:0)-C(18:0)). The method was successfully applied to samples from different sources and consequently, with different composition. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  17. Determination of insoluble soap in agricultural soil and sewage sludge samples by liquid chromatography with ultraviolet detection.

    Science.gov (United States)

    Cantarero, Samuel; Zafra-Gómez, Alberto; Ballesteros, Oscar; Navalón, Alberto; Vílchez, José L; Crovetto, Guillermo; Verge, Coral; de Ferrer, Juan A

    2010-11-01

    We have developed a new analytical procedure for determining insoluble Ca and Mg fatty acid salts (soaps) in agricultural soil and sewage sludge samples. The number of analytical methodologies that focus in the determination of insoluble soap salts in different environmental compartments is very limited. In this work, we propose a methodology that involves a sample clean-up step with petroleum ether to remove soluble salts and a conversion of Ca and Mg insoluble salts into soluble potassium salts using tripotassium ethylenediaminetetraacetate salt and potassium carbonate, followed by the extraction of analytes from the samples using microwave-assisted extraction with methanol. An improved esterification procedure using 2,4-dibromoacetophenone before the liquid chromatography with ultraviolet detection analysis also has been developed. The absence of matrix effect was demonstrated with two fatty acid Ca salts that are not commercial and are never detected in natural samples (C₁₃:₀ and C₁₇:₀). Therefore, it was possible to evaluate the matrix effect because both standards have similar environmental behavior (adsorption and precipitation) to commercial soaps (C₁₀:₀) to C₁₈:₀). We also studied the effect of the different variables on the clean-up, the conversion of Ca soap, and the extraction and derivatization procedures. The quantification limits found ranged from 0.4 to 0.8 mg/kg. The proposed method was satisfactorily applied for the development of a study on soap behavior in agricultural soil and sewage sludge samples. © 2010 SETAC.

  18. Simultaneous determination of sucralose and related compounds by high-performance liquid chromatography with evaporative light scattering detection.

    Science.gov (United States)

    Yan, Wenwu; Wang, Nani; Zhang, Peimin; Zhang, Jiajie; Wu, Shuchao; Zhu, Yan

    2016-08-01

    Sucralose is widely used in food and beverages as sweetener. Current synthesis approaches typically provide sucralose products with varying levels of related chlorinated carbohydrates which can affect the taste and flavor-modifying properties of sucralose. Quantification of related compounds in sucralose is often hampered by the lack of commercially available standards. In this work, nine related compounds were purified (purity>97%) and identified by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR), then a rapid and simple HPLC coupled with evaporative light scattering detection (ELSD) method has been developed for the simultaneous determination of sucralose and related compounds. Under optimized conditions, the method showed good linearity in the range of 2-600μgmL(-1) with determination coefficients R(2)⩾0.9990. Moreover, low limits of detection in the range of 0.5-2.0μgmL(-1) and good repeatability (RSDsucralose quality control and purification process monitoring. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. [Determination of hexane in the acid cluster of caprolactam by high performance liquid chromatography with indirect photometric detection].

    Science.gov (United States)

    Li, Linan; Duan, Zhengkang; Zeng, Hongyan; He, Yuping; Chen, Qiuyun

    2011-01-01

    An indirect photometric detection method for the determination of hexane in the acid cluster of caprolactam by high performance liquid chromatography was developed. Ultraviolet (UV) absorption background reagents were added in the mobile phase, and the hexane, nonabsorption in ultraviolet region, was directly determined by a UV detector. The effects of the mobile phase composition, species and concentration of the background reagents etc. on the analyzed results were studied. The optimization of the separation was performed on an Agilent HC-C18 column (250 mm x 4.6 mm, 5 microm). A solution of methanol-water (85:15, v/v) containing 1.17 mmol/L 1,5-naphthalene disulfonic acid was used as mobile phase at a flow rate of 1.0 mL/min and the column temperature was set at 35 degrees C. The gradient of wavelength was adopted to adjust the relative size of systematic peaks and the target peaks. The linear relationship in the range of 0.5-20 mg/kg with a correlation coefficient of 0.999 93 in this method was obtained. The recoveries and relative standard deviation for the hexane in the acid cluster of caprolactam were 98.45%-102.3% and 2.53%, respectively. The detection limit was 0.03 mg/kg. The method is simple, and has good selectivity, high sensitivity and strong anti-interference ability for the accurate determination of hexane in practical samples quickly.

  20. Novel ionic liquid matrices for qualitative and quantitative detection of carbohydrates by matrix assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Zhao, Xiaoyong; Shen, Shanshan; Wu, Datong; Cai, Pengfei; Pan, Yuanjiang

    2017-09-08

    Analysis of carbohydrates based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is still challenging and researchers have been devoting themselves to efficient matrices discovery. In the present study, the design, synthesis, qualitative and quantitative performance of non-derivative ionic liquid matrices (ILMs) were reported. DHB/N-methylaniline (N-MA) and DHB/N-ethylaniline (N-EA), performing best for carbohydrate detection, have been screened out. The limit of detection for oligosaccharide provided by DHB/N-MA and DHB/N-EA were as low as 10 fmol. DHB/N-MA and DHB/N-EA showed significantly higher ion generation efficiency than DHB. The comparison of capacity to probe polysaccharide between these two ILMs and DHB also revealed their powerful potential. Their outstanding performance were probably due to lower proton affinities and stronger UV absorption at λ = 355 nm. What is more, taking DHB/N-MA as an example, quantitative analysis of fructo-oligosaccharide mixtures extracted and identified from rice noodles has been accomplished sensitively using an internal standard method. Overall, DHB/N-MA and DHB/N-EA exhibited excellent performance and might be significant sources as the carbohydrate matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Simultaneous determination of eight cyclopolypeptide antibiotics in feed by high performance liquid chromatography coupled with evaporation light scattering detection.

    Science.gov (United States)

    Song, Xuqin; Xie, Jingmeng; Zhang, Meiyu; Zhang, Yingxia; Li, Jiufeng; Huang, Qiwen; He, Limin

    2018-02-15

    A high throughput, reliable and reproducible analysis strategy based on high performance liquid chromatography combined to evaporative light scattering detector (HPLC-ELSD) was developed for simultaneous determination of eight cyclopolypeptide antibiotics including vancomycin, polymyxin B (polymyxin B1 and polymyxin B2), polymyxin E (colistin A and colistin B), teicoplanin, bacitracin A, daptomycin and virginiamycin M1 in animal Feed. Feed samples were extracted with methanol-2% formic acid aqueous solution, followed by a solid-phase extraction step using a HLB cartridge. Under the optimum chromatographic conditions and ELSD parameters, target compounds were separated well on a short column filled with biphenyl stationary phase. The method was developed in accordance with pig complete feed and then extended to detect polypeptide antibiotics in piglet premix, pig feed additive, poultry complete feed and fattening pig premix. The results showed that logarithmic calibration curves of eight analytes were linear (r 2  > 0.99) within the concentration range of 5-200 mg mL -1 . The developed method provided good accuracy and precision for quantification of eight polypeptides in five kinds of feeds with recoveries ranging from 72.0% to 105.4% with relative standard deviations <9.5%. The limits of detection ranged from 2 to 5 mg kg -1 . Finally, the method was successfully applied to analyze polypeptide antibiotics in commercial feed. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Liquid Argon Scintillation Detection Utilizing Wavelength-Shifting Plates and Light Guides

    Energy Technology Data Exchange (ETDEWEB)

    Howard, B. [Indiana U.

    2018-02-06

    In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.

  3. p-Terphenyl: An alternative to liquid scintillators for neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Sardet, A., E-mail: alix.sardet@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Varignon, C.; Laurent, B.; Granier, T. [CEA, DAM, DIF, F-91297 Arpajon (France); Oberstedt, A. [CEA, DAM, DIF, F-91297 Arpajon (France); Fundamental Physics, Chalmers University of Technology, S-41296 Göteborg (Sweden)

    2015-08-21

    A detailed characterization of doped paraterphenyl (p-Terphenyl) neutron detectors was obtained by means of γ-sources and a {sup 252}Cf fission chamber. The intrinsic timing resolution, the energy resolution up to 2 MeV{sub ee}, and the electron-equivalent energy calibration were determined using γ-sources. The neutron time-of-flight spectrum from the spontaneous fission of {sup 252}Cf provided information on the proton energy calibration, the light output function, and the intrinsic neutron detection efficiency between 0 and 8 MeV for a threshold of 250 keV. Measurements of the latter were also performed using monoenergetic neutron beams. The applied experimental methods were cross-checked using two BC501A scintillation detectors, which were previously calibrated at the Physikalisch-Technische Bundesanstalt in Braunschweig, Germany. Results were compared to Monte-Carlo simulations performed using NRESP7 and NEFF7 codes.

  4. Liquid argon scintillation detection utilizing wavelength-shifting plates and light guides

    Science.gov (United States)

    Howard, B.

    2018-02-01

    In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.

  5. High catechin concentrations detected in Withania somnifera (ashwagandha by high performance liquid chromatography analysis

    Directory of Open Access Journals (Sweden)

    Sulaiman Siti

    2011-08-01

    Full Text Available Abstract Background Withania somnifera is an important medicinal plant traditionally used in the treatment of many diseases. The present study was carried out to characterize the phenolic acids, flavonoids and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH scavenging activities in methanolic extracts of W. somnifera fruits, roots and leaves (WSFEt, WSREt and WSLEt. Methods WSFEt, WSREt and WSLEt was prepared by using 80% aqueous methanol and total polyphenols, flavonoids as well as DPPH radical scavenging activities were determined by spectrophotometric methods and phenolic acid profiles were determined by HPLC methods. Results High concentrations of both phenolics and flavonoids were detected in all parts of the plant with the former ranging between 17.80 ± 5.80 and 32.58 ± 3.16 mg/g (dry weight and the latter ranging between 15.49 ± 1.02 and 31.58 ± 5.07 mg/g. All of the three different plant parts showed strong DPPH radical scavenging activities (59.16 ± 1.20 to 91.84 ± 0.38%. Eight polyphenols (gallic, syringic, benzoic, p-coumaric and vanillic acids as well as catechin, kaempferol and naringenin have been identified by HPLC in parts of the plant as well. Among all the polyphenols, catechin was detected in the highest concentration (13.01 ± 8.93 to 30.61 ± 11.41 mg/g. Conclusion The results indicating that W. somnifera is a plant with strong therapeutic properties thus further supporting its traditional claims. All major parts of W. somnifera such as the roots, fruits and leaves provide potential benefits for human health because of its high content of polyphenols and antioxidant activities with the leaves containing the highest amounts of polyphenols specially catechin with strong antioxidant properties.

  6. High catechin concentrations detected in Withania somnifera (ashwagandha) by high performance liquid chromatography analysis

    Science.gov (United States)

    2011-01-01

    Background Withania somnifera is an important medicinal plant traditionally used in the treatment of many diseases. The present study was carried out to characterize the phenolic acids, flavonoids and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activities in methanolic extracts of W. somnifera fruits, roots and leaves (WSFEt, WSREt and WSLEt). Methods WSFEt, WSREt and WSLEt was prepared by using 80% aqueous methanol and total polyphenols, flavonoids as well as DPPH radical scavenging activities were determined by spectrophotometric methods and phenolic acid profiles were determined by HPLC methods. Results High concentrations of both phenolics and flavonoids were detected in all parts of the plant with the former ranging between 17.80 ± 5.80 and 32.58 ± 3.16 mg/g (dry weight) and the latter ranging between 15.49 ± 1.02 and 31.58 ± 5.07 mg/g. All of the three different plant parts showed strong DPPH radical scavenging activities (59.16 ± 1.20 to 91.84 ± 0.38%). Eight polyphenols (gallic, syringic, benzoic, p-coumaric and vanillic acids as well as catechin, kaempferol and naringenin) have been identified by HPLC in parts of the plant as well. Among all the polyphenols, catechin was detected in the highest concentration (13.01 ± 8.93 to 30.61 ± 11.41 mg/g). Conclusion The results indicating that W. somnifera is a plant with strong therapeutic properties thus further supporting its traditional claims. All major parts of W. somnifera such as the roots, fruits and leaves provide potential benefits for human health because of its high content of polyphenols and antioxidant activities with the leaves containing the highest amounts of polyphenols specially catechin with strong antioxidant properties. PMID:21854608

  7. Comparison of liquid-based cytology with conventional cytology for detection of cervical cancer precursors: a randomized controlled trial.

    NARCIS (Netherlands)

    Siebers, A.G.; Klinkhamer, P.J.; Grefte, J.M.M.; Massuger, L.F.A.G.; Vedder, J.E.; Beijers-Broos, A.; Bulten, J.; Arbyn, M.

    2009-01-01

    CONTEXT: Liquid-based cytology has been developed as an alternative for conventional cervical cytology. Despite numerous studies and systematic reviews, controversy remains about its diagnostic accuracy. OBJECTIVE: To assess the performance of liquid-based cytology compared with conventional

  8. Dielectric breakdown of fast switching LCD shutters

    Science.gov (United States)

    Mozolevskis, Gatis; Sekacis, Ilmars; Nitiss, Edgars; Medvids, Arturs; Rutkis, Martins

    2017-02-01

    Fast liquid crystal optical shutters due to fast switching, vibrationless control and optical properties have found various applications: substitutes for mechanical shutters, 3D active shutter glasses, 3D volumetric displays and more. Switching speed depends not only on properties of liquid crystal, but also on applied electric field intensity. Applied field in the shutters can exceed >10 V/micron which may lead to dielectric breakdown. Therefore, a dielectric thin film is needed between transparent conductive electrodes in order to reduce breakdown probability. In this work we have compared electrical and optical properties of liquid crystal displays with dielectric thin films with thicknesses up to few hundred nanometers coated by flexo printing method and magnetron sputtering. Dielectric breakdown values show flexographic thin films to have higher resistance to dielectric breakdown, although sputtered coatings have better optical properties, such as higher transmission and no coloration.

  9. Roughened glass slides and a spectrophotometer for the detection of the wavelength-dependent refractive index of transparent liquids.

    Science.gov (United States)

    Niskanen, Ilpo; Räty, Jukka; Myllylä, Risto; Sutinen, Veijo; Matsuda, Kiyofumi; Homma, Kazuhiro; Silfsten, Pertti; Peiponen, Kai-Erik

    2012-07-01

    We describe a method to determine the wavelength-dependent refractive index of liquids by measurement of light transmittance with a spectrophotometer. The method is based on using roughened glass slides with different a priori known refractive indices and immersing the slides into the transparent liquid with unknown refractive index. Using the dispersion data on the glass material it is possible to find the index match between the liquid and the glass slide, and hence the refractive index of the liquid.

  10. Diffusional mechanisms augment the fluorine MR relaxation in paramagnetic perfluorocarbon nanoparticles that provides a "relaxation switch" for detecting cellular endosomal activation.

    Science.gov (United States)

    Hu, Lingzhi; Zhang, Lei; Chen, Junjie; Lanza, Gregory M; Wickline, Samuel A

    2011-09-01

    To develop a physical model for the (19)F relaxation enhancement in paramagnetic perfluorocarbon nanoparticles (PFC NP) and demonstrate its application in monitoring cellular endosomal functionality through a "(19)F relaxation switch" phenomenon. An explicit expression for (19)F longitudinal relaxation enhancement was derived analytically. Monte-Carlo simulation was performed to confirm the gadolinium-induced magnetic field inhomogeneity inside the PFC NP. Field-dependent T(1) measurements for three types of paramagnetic PFC NPs were carried out to validate the theoretical prediction. Based on the physical model, (19)F and (1)H relaxation properties of macrophage internalized paramagnetic PFC NPs were measured to evaluate the intracellular process of NPs by macrophages in vitro. The theoretical description was confirmed experimentally by field-dependent T(1) measurements. The shortening of (19)F T(1) was found to be attributed to the Brownian motion of PFC molecules inside the NP in conjunction with their ability to permeate into the lipid surfactant coating. A dramatic change of (19)F T(1) was observed upon endocytosis, revealing the transition from intact bound PFC NP to processed constituents. The proposed first-principle analysis of (19)F spins in paramagnetic PFC NP relates their structural parameters to the special MR relaxation features. The demonstrated "(19)F relaxation switch" phenomenon is potentially useful for monitoring cellular endosomal functionality. Copyright © 2011 Wiley-Liss, Inc.

  11. Determination of Cinchona alkaloids and Vitamin B{sub 6} by high-performance liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Gatti, R.; Gioia, M.G.; Cavrini, V

    2004-06-04

    A simple and specific method has been developed for the simultaneous determination of the four major Cinchona alkaloids and their dihydroderivatives and pyridoxine hydrochloride (Vitamin B{sub 6}) by high-performance liquid chromatography (HPLC) with fluorescence detection ({lambda}{sub em}=420 nm with {lambda}{sub ex}=330 nm). The chromatographic separation was performed on a Phenomenex Prodigy ODS column (5 {mu}m, 250 mmx3.2 mm i.d.), recommended for basic compounds, under isocratic reversed-phase conditions. The method allowed a good peak shape and an effective resolution of the tested compounds. The extraction of alkaloids from the Cinchona succirubra bark was carried out in mild and fast conditions (ambient temperature, 20 min) by ultrasonication. The procedure showed to be advantageous respect to a reference method, which involved Soxhlet extraction. The results were compared statistically by means of the Student's t-test and the variance ratio F-test; no significant difference was found. The method was reproducible (relative standard deviations in the range of 1.0-5.0% for the different alkaloids) and gave quantitative recovery of alkaloids added to bark samples (97.8-105%). For additional informations a photoreactor was arranged between the analytical column and the detector and the online post-column photochemical conversion (irradiation=254 nm) was investigated. Vitamin B{sub 6} was shown to be highly photosensitive, giving significantly different fluorescence spectra with and without UV irradiation. The proposed method was successfully applied to the quality control of Cinchona bark, liquid extract and cosmetics.

  12. Migration of bisphenol A from polycarbonate baby bottles purchased in the Spanish market by liquid chromatography and fluorescence detection.

    Science.gov (United States)

    Santillana, M I; Ruiz, E; Nieto, M T; Bustos, J; Maia, J; Sendón, R; Sánchez, J J

    2011-11-01

    During the last decade the safety of bisphenol A (BPA) monomer in polycarbonate baby bottles has drawn the attention of both the public and the scientific community. This paper presents the results of BPA migration from polycarbonate baby bottles bought in the Spanish market, into simulant B (3% acetic acid), 50% ethanol and into real food (reconstituted infant formula). Furthermore, it was also the objective of this study to assess the suitability of 50% ethanol as a simulant for infant formula. BPA was analysed by a multi-analyte liquid chromatography method with fluorescence detection and mass spectrometry confirmation. The method was in-house validated and accredited by the national accreditation body. The validation results for this analyte in the previous mentioned matrices were: LOD = 0.004-0.007 mg kg(-1); LOQ (validated) = 0.03 mg kg(-1); RSD% = 3.4-5.8; and recovery = 106.6-118.2%. A collection of 72 different baby bottle samples from 12 different brands were analysed. Baby bottle material was identified by FTIR. The migration test conditions used were those recommended for baby bottles in the Guidelines on testing conditions for articles in contact with foodstuffs (with a focus on kitchenware), prepared by the European network of laboratories for food-contact materials. In most of the migration assays the results were below the LOD. In four of the commercial brands there was detectable migration into the simulant 50% ethanol and BPA was detected in only two samples of infant formula (0.01 mg kg(-1)). Migration results obtained were in compliance with European Union regulations.

  13. Screen-Printed Graphite Electrodes as Low-Cost Devices for Oxygen Gas Detection in Room-Temperature Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Junqiao Lee

    2017-11-01

    Full Text Available Screen-printed graphite electrodes (SPGEs have been used for the first time as platforms to detect oxygen gas in room-temperature ionic liquids (RTILs. Up until now, carbon-based SPEs have shown inferior behaviour compared to platinum and gold SPEs for gas sensing with RTIL solvents. The electrochemical reduction of oxygen (O2 in a range of RTILs has therefore been explored on home-made SPGEs, and is compared to the behaviour on commercially-available carbon SPEs (C-SPEs. Six common RTILs are initially employed for O2 detection using cyclic voltammetry (CV, and two RTILs ([C2mim][NTf2] and [C4mim][PF6] chosen for further detailed analytical studies. Long-term chronoamperometry (LTCA was also performed to test the ability of the sensor surface for real-time gas monitoring. Both CV and LTCA gave linear calibration graphs—for CV in the 10–100% vol. range, and for LTCA in the 0.1–20% vol. range—on the SPGE. The responses on the SPGE were far superior to the commercial C-SPEs; more instability in the electrochemical responses were observed on the C-SPEs, together with some breaking-up or dissolution of the electrode surface materials. This study highlights that not all screen-printed ink formulations are compatible with RTIL solvents for longer-term electrochemical experiments, and that the choice of RTIL is also important. Overall, the low-cost SPGEs appear to be promising platforms for the detection of O2, particularly in [C4mim][PF6].

  14. Detection of singly- and doubly-charged quaternary ammonium drugs in equine urine by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Ho, Emmie N M; Kwok, W H; Wong, April S Y; Wan, Terence S M

    2012-01-13

    Quaternary ammonium drugs (QADs) are anticholinergic agents some of which are known to have been abused or misused in equine sports. A recent review of literature shows that the screening methods reported thus far for QADs mainly cover singly-charged QADs. Doubly-charged QADs are extremely polar substances which are difficult to be extracted and poorly retained on reversed-phase columns. It would be ideal if a comprehensive method can be developed which can detect both singly- and doubly-charged QADs. This paper describes an efficient liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous detection and confirmation of 38 singly- and doubly-charged QADs at sub-parts-per-billion (ppb) to low-ppb levels in equine urine after solid-phase extraction. Quaternary ammonium drugs were extracted from equine urine by solid-phase extraction (SPE) using an ISOLUTE(®) CBA SPE column and analysed by LC/MS/MS in the positive electrospray ionisation mode. Separation of the 38 QADs was achieved on a polar group embedded C18 LC column with a mixture of aqueous ammonium formate (pH 3.0, 10 mM) and acetonitrile as the mobile phase. Detection and confirmation of the 38 QADs at sub-ppb to low-ppb levels in equine urine could be achieved within 16 min using selected reaction monitoring (SRM). Matrix interference of the target transitions at the expected retention times was not observed. Other method validation data, including precision and recovery, were acceptable. The method was successfully applied to the analyses of drug-administration samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Screen-Printed Graphite Electrodes as Low-Cost Devices for Oxygen Gas Detection in Room-Temperature Ionic Liquids.

    Science.gov (United States)

    Lee, Junqiao; Hussain, Ghulam; Banks, Craig E; Silvester, Debbie S

    2017-11-26

    Screen-printed graphite electrodes (SPGEs) have been used for the first time as platforms to detect oxygen gas in room-temperature ionic liquids (RTILs). Up until now, carbon-based SPEs have shown inferior behaviour compared to platinum and gold SPEs for gas sensing with RTIL solvents. The electrochemical reduction of oxygen (O₂) in a range of RTILs has therefore been explored on home-made SPGEs, and is compared to the behaviour on commercially-available carbon SPEs (C-SPEs). Six common RTILs are initially employed for O₂ detection using cyclic voltammetry (CV), and two RTILs ([C₂mim][NTf₂] and [C₄mim][PF₆]) chosen for further detailed analytical studies. Long-term chronoamperometry (LTCA) was also performed to test the ability of the sensor surface for real-time gas monitoring. Both CV and LTCA gave linear calibration graphs-for CV in the 10-100% vol. range, and for LTCA in the 0.1-20% vol. range-on the SPGE. The responses on the SPGE were far superior to the commercial C-SPEs; more instability in the electrochemical responses were observed on the C-SPEs, together with some breaking-up or dissolution of the electrode surface materials. This study highlights that not all screen-printed ink formulations are compatible with RTIL solvents for longer-term electrochemical experiments, and that the choice of RTIL is also important. Overall, the low-cost SPGEs appear to be promising platforms for the detection of O₂, particularly in [C₄mim][PF₆].

  16. DETECTING LOW-LEVEL SYNTHESIS IMPURITIES IN MODIFIED PHOSPHOROTHIOATE OLIGONUCLEOTIDES USING LIQUID CHROMATOGRAPHY – HIGH RESOLUTION MASS SPECTROMETRY

    Science.gov (United States)

    Nikcevic, Irena; Wyrzykiewicz, Tadeusz K.; Limbach, Patrick A.

    2010-01-01

    Summary An LC-MS method based on the use of high resolution Fourier transform ion cyclotron resonance mass spectrometry (FTIRCMS) for profiling oligonucleotides synthesis impurities is described. Oligonucleotide phosphorothioatediesters (phosphorothioate oligonucleotides), in which one of the non-bridging oxygen atoms at each phosphorus center is replaced by a sulfur atom, are now one of the most popular oligonucleotide modifications due to their ease of chemical synthesis and advantageous pharmacokinetic properties. Despite significant progress in the solid-phase oligomerization chemistry used in the manufacturing of these oligonucleotides, multiple classes of low-level impurities always accompany synthetic oligonucleotides. Liquid chromatography-mass spectrometry has emerged as a powerful technique for the identification of these synthesis impurities. However, impurity profiling, where the entire complement of low-level synthetic impurities is identified in a single analysis, is more challenging. Here we present an LC-MS method based the use of high resolution-mass spectrometry, specifically Fourier transform ion cyclotron resonance mass spectrometry (FTIRCMS or FTMS). The optimal LC-FTMS conditions, including the stationary phase and mobile phases for the separation and identification of phosphorothioate oligonucleotides, were found. The characteristics of FTMS enable charge state determination from single m/z values of low-level impurities. Charge state information then enables more accurate modeling of the detected isotopic distribution for identification of the chemical composition of the detected impurity. Using this approach, a number of phosphorothioate impurities can be detected by LC-FTMS including failure sequences carrying 3′-terminal phosphate monoester and 3′-terminal phosphorothioate monoester, incomplete backbone sulfurization and desulfurization products, high molecular weight impurities, and chloral, isobutyryl, and N3 (2-cyanoethyl) adducts

  17. Quantification of five plasticizers used in PVC tubing through high performance liquid chromatographic-UV detection.

    Science.gov (United States)

    Radaniel, Tsanta; Genay, Stéphanie; Simon, Nicolas; Feutry, Frédéric; Quagliozzi, Francesca; Barthélémy, Christine; Lecoeur, Marie; Sautou, Valérie; Décaudin, Bertrand; Odou, Pascal

    2014-08-15

    Searching for alternatives to di-(2-ethylhexyl)-phthalate, a plasticizer that has been widely used in the manufacturing of PVC medical devices, has become a major challenge since a European regulation underlined some clinical risks. The aim of this study is to develop an HPLC-UV method to quantify the currently used alternative plasticizers to DEHP. Five plasticizers, acetyl tributyl citrate, di-(2-ethylhexyl)-phthalate, di-(ethylhexyl)-terephthalate, di-isononyl-1,2-cyclohexane-dicarboxylate, and trioctyl trimellitate, were separated on a C8 stationary phase (2.6 μm, 100 mm × 4.6mm) under gradient elution in 13 min. They were detected at 221 nm leading to a quantification threshold from 0.3 to 750 μg/mL as a function of the plasticizer. Within-day and between-day precisions were inferior to 0.9% and 18%, respectively. The assays were validated according to the accuracy profile method. Plasticizers were extracted from PVC-tubing by dissolving PVC in THF then precipitating it in methanol with a yield of over 90% for each plasticizer. This assay could feasibly be used to quantify plasticizers in PVC medical devices. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Adaptive Fault Detection on Liquid Propulsion Systems with Virtual Sensors: Algorithms and Architectures

    Science.gov (United States)

    Matthews, Bryan L.; Srivastava, Ashok N.

    2010-01-01

    Prior to the launch of STS-119 NASA had completed a study of an issue in the flow control valve (FCV) in the Main Propulsion System of the Space Shuttle using an adaptive learning method known as Virtual Sensors. Virtual Sensors are a class of algorithms that estimate the value of a time series given other potentially nonlinearly correlated sensor readings. In the case presented here, the Virtual Sensors algorithm is based on an ensemble learning approach and takes sensor readings and control signals as input to estimate the pressure in a subsystem of the Main Propulsion System. Our results indicate that this method can detect faults in the FCV at the time when they occur. We use the standard deviation of the predictions of the ensemble as a measure of uncertainty in the estimate. This uncertainty estimate was crucial to understanding the nature and magnitude of transient characteristics during startup of the engine. This paper overviews the Virtual Sensors algorithm and discusses results on a comprehensive set of Shuttle missions and also discusses the architecture necessary for deploying such algorithms in a real-time, closed-loop system or a human-in-the-loop monitoring system. These results were presented at a Flight Readiness Review of the Space Shuttle in early 2009.

  19. Molecular Biosensors for Electrochemical Detection of Infectious Pathogens in Liquid Biopsies: Current Trends and Challenges

    Science.gov (United States)

    Yáñez-Sedeño, Paloma

    2017-01-01

    Rapid and reliable diagnosis of infectious diseases caused by pathogens, and timely initiation of appropriate treatment are critical determinants to promote optimal clinical outcomes and general public health. Conventional in vitro diagnostics for infectious diseases are time-consuming and require centralized laboratories, experienced personnel and bulky equipment. Recent advances in electrochemical affinity biosensors have demonstrated to surpass conventional standards in regards to time, simplicity, accuracy and cost in this field. The tremendous potential offered by electrochemical affinity biosensors to detect on-site infectious pathogens at clinically relevant levels in scarcely treated body fluids is clearly stated in this review. The development and application of selected examples using different specific receptors, assay formats and electrochemical approaches focusing on the determination of specific circulating biomarkers of different molecular (genetic, regulatory and functional) levels associated with bacterial and viral pathogens are critically discussed. Existing challenges still to be addressed and future directions in this rapidly advancing and highly interesting field are also briefly pointed out. PMID:29099764

  20. An on-line coupling of nanofibrous extraction with column-switching high performance liquid chromatography - A case study on the determination of bisphenol A in environmental water samples.

    Science.gov (United States)

    Háková, Martina; Chocholoušová Havlíková, Lucie; Chvojka, Jiří; Solich, Petr; Šatínský, Dalibor

    2018-02-01

    Polyamide 6 nanofiber polymers were used as modern sorbents for on-line solid phase extraction (SPE) coupled with liquid chromatography. The on-line SPE system was tested for the determination of bisphenol A in river water samples. Polyamide nanofibers were prepared using needleless electrospinning, inserted into a mini-column cartridge (5 × 4.6mm) and coupled with HPLC. The effect of column packing and the amount of polyamide 6 on extraction efficiency was tested and the packing process was optimized. The proposed method was performed using a 50-µL sample injection followed by an on-line nanofibrous extraction procedure. The influence of the washing mobile phase on the retention of bisphenol A during the extraction procedure was evaluated. Ascentis ® Express C18 (10cm × 4.6mm) core-shell column was used as an analytical column. Fluorescence detection wavelengths (λ ex = 225nm and λ em = 320nm) were used for identification and quantification of Bisphenol A in river waters. The linearity was tested in the range from 2 to 500µgL -1 (using nine calibration points). The limits of detection and quantification were 0.6 and 2µgL -1 , respectively. The developed method was successfully used for the determination of bisphenol A in various samples of river waters in the Czech Republic (The Ohře, Labe, Nisa, Úpa, and Opava Rivers). Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Quantitative determination of azithromycin in plasma, blood and isolated neutrophils by liquid chromatography using pre-column derivatization with 9-fluorenylmethyloxycarbonyl-chloride and fluorescence detection

    NARCIS (Netherlands)

    Wilms, Erik; Trumpie, Henk; Veenendaal, Wim; Touw, Daan

    2005-01-01

    In this study, a high-performance liquid chromatographic method with pre-column derivatization and fluorescence detection was optimised and validated for the quantification of azithromycin (AZM) in plasma. Clarithromycin (CLM) was used as an internal standard. Pre-column derivatization was done with

  2. Can high-performance liquid chromatography coupled with fluorescence detection under all conditions be regarded as a sufficiently conclusive confirmatory method for B-group substances?

    NARCIS (Netherlands)

    Zuidema, T.; Mulder, P.P.J.; Lasaroms, J.J.P.; Stappers, S.J.W.; Rhijn, van J.A.

    2006-01-01

    Commission Decision 2002/657/EC requires confirmatory analysis of B-group compounds when detected at levels above the permitted limit. In contrast to banned substances, for B-group substances, the use of mass spectrometric techniques is not obligatory and several techniques including liquid

  3. Air-assisted liquid-liquid microextraction-gas chromatography-flame ionisation detection: a fast and simple method for the assessment of triazole pesticides residues in surface water, cucumber, tomato and grape juices samples.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Khoshmaram, Leila

    2013-12-01

    A recently reported microextraction technique namely air-assisted liquid-liquid microextraction (AALLME) has been described for the extraction/preconcentration of some triazole pesticides from different samples prior to gas chromatography-flame ionisation detection (GC-FID). This technique is similar to dispersive liquid-liquid microextraction (DLLME) but in this method there is no need to use a disperser solvent and also volume of the used extraction solvent is less than DLLME. In this study, toluene with a density lower than that of water was used as an extraction solvent. Under the optimum extraction conditions, the method showed wide linear ranges with R(2)>0.996 and low limits of detection and quantification between 0.53-1.13 and 1.76-3.77 ng mL(-1), respectively. Enrichment factors (EFs) and extraction recoveries (ERs) were in the ranges of 713-808 and 100-113%, respectively. Relative standard deviations (RSDs) for the extraction of 25 and 250 ng mL(-1) of each selected triazole pesticide were less than 7% for intra-day (n=6) and inter-days (n=5) precision. The method was successfully used for analytes determination in different surface water, grape juice, cucumber, and tomato samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Bio-analytical method development and validation of Rasagiline by high performance liquid chromatography tandem mass spectrometry detection and its application to pharmacokinetic study

    Directory of Open Access Journals (Sweden)

    Ravi Kumar Konda

    2012-10-01

    Full Text Available The most suitable bio-analytical method based on liquid–liquid extraction has been developed and validated for quantification of Rasagiline in human plasma. Rasagiline-13C3 mesylate was used as an internal standard for Rasagiline. Zorbax Eclipse Plus C18 (2.1 mm×50 mm, 3.5 μm column provided chromatographic separation of analyte followed by detection with mass spectrometry. The method involved simple isocratic chromatographic condition and mass spectrometric detection in the positive ionization mode using an API-4000 system. The total run time was 3.0 min. The proposed method has been validated with the linear range of 5–12000 pg/mL for Rasagiline. The intra-run and inter-run precision values were within 1.3%–2.9% and 1.6%–2.2% respectively for Rasagiline. The overall recovery for Rasagiline and Rasagiline-13C3 mesylate analog was 96.9% and 96.7% respectively. This validated method was successfully applied to the bioequivalence and pharmacokinetic study of human volunteers under fasting condition. Keywords: High performance liquid chromatography, Mass spectrometry, Rasagiline, Liquid–liquid extraction

  5. Spray-inlet microwave plasma torch ionization tandem mass spectrometry for the direct detection of drug samples in liquid solutions.

    Science.gov (United States)

    Miao, Meng; Zhao, Gaosheng; Wang, Yaliang; Xu, Li; Dong, Junguo; Cheng, Ping

    2017-12-30

    Drug abuse or dependence results in a series of social problems, including crime and traffic accidents. Spray-inlet microwave plasma torch tandem mass spectrometry (MPT-MS/MS) was developed and used for the direct detection of such drugs in liquid solutions. Drug sample solutions were directly sprayed into the flame of an MPT by a sampling pump and the ions produced by Penning ionization and ion-molecule reactions were guided into a quadrupole time-of-flight (QTOF) tandem mass spectrometer for mass analysis. The MPT was operated at 40 W and 2.45 GHz in a 700 mL/min argon flow both for the inner and middle plasma. Intact quasi-molecular and molecular ions of various drugs were successfully characterized by spray-inlet MPT-MS/MS. The analysis of one sample was finished within 30 s. Furthermore, the method exhibited excellent efficiency, precision and sensitivity, and the limits of detection and limits of quantification of the samples in methanol were in the range of 5.25-60.0 and 17.5-200 ng g -1 , respectively. Excellent linearities with coefficients of determination (R 2 ) of 0.9627-0.9980 were verified in the range 0.05-50 μg g -1 . Four different beverages purchased locally were also analyzed with spray-inlet MPT-MS/MS, and caffeine was directly determined in two of the beverages. By adding six standard drug samples to sport drinks (each drug was 1 μg g -1 ) and Chinese spirit (each drug was 0.1 μg g -1 ), all the drugs except for caffeine were detected successfully. This study indicates that spay-inlet MPT-MS/MS is an effective method for direct and rapid identification of drug solutions, and it has substantial potential for fast and sensitive drug residue detection. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Saturated Switching Systems

    CERN Document Server

    Benzaouia, Abdellah

    2012-01-01

    Saturated Switching Systems treats the problem of actuator saturation, inherent in all dynamical systems by using two approaches: positive invariance in which the controller is designed to work within a region of non-saturating linear behaviour; and saturation technique which allows saturation but guarantees asymptotic stability. The results obtained are extended from the linear systems in which they were first developed to switching systems with uncertainties, 2D switching systems, switching systems with Markovian jumping and switching systems of the Takagi-Sugeno type. The text represents a thoroughly referenced distillation of results obtained in this field during the last decade. The selected tool for analysis and design of stabilizing controllers is based on multiple Lyapunov functions and linear matrix inequalities. All the results are illustrated with numerical examples and figures many of them being modelled using MATLAB®. Saturated Switching Systems will be of interest to academic researchers in con...

  7. Effective switching frequency multiplier inverter

    Science.gov (United States)

    Su, Gui-Jia; Peng, Fang Z.

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  8. FreeSWITCH Cookbook

    CERN Document Server

    Minessale, Anthony

    2012-01-01

    This is a problem-solution approach to take your FreeSWITCH skills to the next level, where everything is explained in a practical way. If you are a system administrator, hobbyist, or someone who uses FreeSWITCH on a regular basis, this book is for you. Whether you are a FreeSWITCH expert or just getting started, this book will take your skills to the next level.

  9. Liquid chromatography-UV diode-array detection method for multi-residue determination of macrolide antibiotics in sheep's milk.

    Science.gov (United States)

    García-Mayor, M A; Garcinuño, R M; Fernández-Hernando, P; Durand-Alegría, J S

    2006-07-28

    A rapid, simple and sensitive liquid chromatography-UV diode-array detection method was developed for the simultaneous determination of seven macrolides (erythromycin, oleandomycin, roxithromycin, josamycin, spiramycin, tylosin and ivermectin) in sheep's milk. The column, mobile phase, temperature and flow rate were optimised to provide the best resolution of these analytes. The extraction of the antibiotic residues involves the treatment of protein-free samples with a combination of concentrated sodium hydroxide and ethyl acetate. Necessary defatting is achieved by alkaline hydrolysis. The recovery of each antibiotic was between 55% and 77%, with relative standard deviations ranging from 1% to 6.5%. The limit of quantification was 72.4 microg/kg for ivermectin, 48.3 microg/kg for roxithromycin, and 24.1 microg/kg for erythromycin, oleandomycin, spiramycin, josamycin and tylosin. The procedure was successfully used in the multi-residue determination of these macrolides at levels below the maximum concentrations legally allowed in milk samples.

  10. Simultaneous analysis of guaiacol and vanillin in a vanilla extract by using high-performance liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Takahashi, Makoto; Sakamaki, Shizuka; Fujita, Akira

    2013-01-01

    We developed and validated a new high-performance liquid chromatographic analysis for electrochemically detecting guaiacol and vanillin as important components in vanilla extract. Separation was achieved with Capcell Pak C-18 MG, the potential of the working electrode being set at +1000 mV. The respective calibration curves for guaiacol and vanillin were linear in the range of 1.60-460 µg/L and 5.90-1180 µg/L. The respective limits for the quantities of guaiacol and vanillin were 1.60 µg/L and 2.36 µg/L. The related standard deviations of the intra- and inter-day precision of the retention time and peak area were all less than 4%. The recovery of guaiacol and vanillin was both more than 97%, all of the validation data being within an acceptable range. This analysis method is well suited for the simultaneous and convenient analysis of guaiacol and vanillin in a vanilla extract to evaluate the quality of the vanilla extract.

  11. Investigation of the immunogenicity of a protein drug using equilibrium dialysis and liquid chromatography tandem mass spectrometry detection.

    Science.gov (United States)

    Ji, Qin C; Rodila, Ramona; Morgan, Sherry J; Humerickhouse, Rod A; El-Shourbagy, Tawakol A

    2005-09-01

    Biotherapeutics such as protein and peptide drugs have attracted significant attention in the medical community and pharmaceutical industry in recent years. Immunogenicity is one of the major concerns in the development and application of biotherapeutics. Although great efforts have been put forth in reducing immunogenicity, monitoring the free ("active") drug concentration and the antibody formation is critical for preclinical and clinical studies. Currently, it is still a challenging task to have a standardized test method monitoring immunogenicity when biotherapeutic compounds such as proteins and peptides are administrated. Combined with liquid chromatography/tandem mass spectrometry detection, the equilibrium dialysis technique that is conventionally used for measuring the free and bound concentration of small organic molecules was extended to the application of measuring the free and bound concentrations of a protein drug with a relative molecular mass over 10,000 from plasma samples containing antibody. This novel approach could also be used for accurately measuring the antibody concentration when a reference standard of the antibody is available.

  12. Automatic detection of recoil proton tracks and background rejection in liquid scintillator-micro-capillary-array fast neutron spectrometer

    Science.gov (United States)

    Mor, I.; Vartsky, D.; Dangendorf, V.; Tittelmeier, K.; Goldberg, M. B.; Bar, D.; Brandis, M.

    2017-12-01

    We describe results on automatic detection of fast-neutron induced recoil-proton tracks in micro-capillary bundles filled with organic liquid scintillator, viewed by an intensified CCD camera. This imaging neutron spectrometer was developed for high position-resolution (few tens of μ m) imaging and medium-quality energy spectroscopy of neutrons in the energy range 2–20 MeV. In addition to recoil proton events which display a continuous extended track structure, CCD images include also a multitude of isolated spots of varying intensity ("blobs") that originate from several different sources, such as fragmented proton tracks, electrons from gamma-rays, short heavy-ion tracks, as well as events and noise that occur in the image intensifier and CCD. In order to identify the extended-track recoil proton events and separate them from these background events, a computerized, rapid and automatic track-recognition procedure was developed. Based on the analysis of track parameters such as: track area, light intensity, track length and width, the method is capable of distinguishing few recoil protons from the surrounding numerous background events typically found in each CCD frame.

  13. Determination of polyacetylenes in carrot roots (Daucus carota L.) by high-performance liquid chromatography coupled with diode array detection.

    Science.gov (United States)

    Christensen, Lars P; Kreutzmann, Stine

    2007-03-01

    A new high-performance liquid chromatographic method with diode array detection was developed for the separation and simultaneous determination of the carrot polyacetylenes falcarindiol (FaDOH), falcarindiol 3-acetate (FaDOAc) and falcarinol (FaOH) in carrot root extracts. The optimal chromatographic conditions were achieved on a C18 column with a linear gradient elution of water and acetonitrile as mobile phases, at the flow rate of 1.0 mL/min. All calibration curves of the three carrot polyacetylenes showed good linear regression (R2 > 0.998) within the test ranges. The developed method showed good precision for quantification of all polyacetylenes with overall intraday and interday variation of less than 3.3% and with average recovery rates of 99.2, 96.8 and 99.7% for FaDOH, FaDOAc and FaOH, respectively. The LOD (S/N = 3) and LOQ (S/N = 10) were less than 0.19 and 0.42 microg/mL, respectively, for all analytes. The established method was successfully used to determine the spatial distribution of FaDOH, FaDOAc and FaOH in six carrot genotypes (Bolero, Independent, Line 1, Mello Yello, Purple Haze and Tornado) by analysing peeled carrots and the corresponding peels for these polyacetylenes.

  14. Quantification of polyacetylenes in apiaceous plants by high-performance liquid chromatography coupled with diode array detection.

    Science.gov (United States)

    Kramer, Maike; Mühleis, Andrea; Conrad, Jürgen; Leitenberger, Martin; Beifuss, Uwe; Carle, Reinhold; Kammerer, Dietmar R

    2011-01-01

    Polyacetylenes are known for their biofunctional properties in a wide range of organisms. In the present study, the most frequently occurring polyacetylenes, i.e. falcarinol, falcarindiol, and falcarindiol-3-acetate, were determined in six genera of the Apiaceae family. For this purpose, a straightforward and reliable method for the screening and quantification of the polyacetylenes using high-performance liquid chromatography coupled with diode array and mass spectrometric detection without tedious sample clean-up has been developed. Peak assignment was based on retention times, UV spectra, and mass spectral data. Quantification was carried out using calibration curves of authentic standards isolated from turnip-rooted parsley and Ligusticum mutellina, respectively. The references were unambiguously identified by Fourier transform-IR (FT-IR) spectroscopy, GC-MS, HPLC-MSn in the positive ionization mode, and 1H NMR and 13C NMR spectroscopy. To the best of our knowledge, the occurrence of falcarindiol-3-acetate in Anthriscus sylvestris and Pastinaca sativa has been reported for the first time. The data revealed great differences in the polyacetylene contents and varying proportions of individual compounds in the storage roots of Apiaceous plants. The results of the present study may be used as a suitable tool for authenticity control and applied to identify novel sources devoid or particularly rich in polyacetylenes, thus facilitating breeding programs for the selective enrichment and depletion of these plant secondary metabolites, respectively.

  15. A novel method to detect seven microcystins in hard clam and corbicula fluminea by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Yang, Bo; Xu, Jin-Zhong; Ding, Tao; Wu, Bin; Jing, Su; Ding, Shu-jing; Chen, Hui-Lan; Sheng, Chong-Yu; Jiang, Yuan

    2009-11-01

    A simple and reliable method to detect seven microcystins in hard clam and corbicula fluminea, based on liquid chromatography with electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS), was developed and validated. The sample preparation procedure includes extraction of tissue by methanol, followed by cleanup on a reversed-phase solid phase extraction (SPE) cartridge. With the optimized method, recoveries were between 43.7% and 92.3% for hard clam, 54.3% and 93.8% for corbicula fluminea, the relative standard deviations (RSD) were less than or equal to 16.2% and 15.7% in hard clam and corbicula fluminea at spiking levels of 1 microg/kg, 2 microg/kg and 5 microg/kg for MC-RR, MC-YR, MC-LR, and MC-LY, and 2 microg/kg, 5 microg/kg and 10 microg/kg for MC-LA, MC-LW and MC-LF, respectively, the limits of quantitation (LOQ) of this method were ranged from 0.7 microg/kg to 2.0 microg/kg.

  16. Determination of Four Anti-epileptic Drugs in Plasma Using Ultra Performance Liquid Chromatography with Mass Detection Technique.

    Science.gov (United States)

    Hassib, Sonia T; Hashem, Hanaa M A; Mahrouse, Marianne A; Mostafa, Eman A

    2018-04-10

    Status epilepticus (SE) is considered the second most frequent neurologic emergency. Its therapeutic management is performed using sequential anti-epileptic drug regimens. Diazepam (DIA), midazolam (MID), phenytoin (PHT) and phenobarbital (PB) are four drugs of different classes used sequentially in the management of SE. A sensitive, selective, accurate and precise method was developed and validated for simultaneous determination of the four anti-epileptic drugs in human plasma. Their separation and quantification were achieved using ultra performance liquid chromatography (UPLC) with mass detection using carbamazepine as internal standard (IS). For the first three drugs and IS, UPLC-MS/MS with electrospray ionization working in multiple reaction monitoring mode was used at the following transitions: m/z 285→193 for DIA, m/z 326→291 for MID, m/z 253→182 for PHT and m/z 237→194, 237→192 for IS. For the fourth drug (PB), molecular ion peak of PB [M+H] + at m/z 233 was used for its quantitation. The method was linear over concentration ranges of 5-500 ng/ml for DIA and MID and 0.25-20 μg/ml for PHT and PB, respectively. Bio-analytical validation of the developed method was carried out according to European Medicines Agency guidelines. The developed method can be applied for routine drug analysis, therapeutic drug monitoring and bioequivalence studies. This article is protected by copyright. All rights reserved.

  17. Gas chromatography-mass spectrometry and high-performance liquid chromatography-diode array detection for dating of paper ink.

    Science.gov (United States)

    Díaz-Santana, Oscar; Vega-Moreno, Daura; Conde-Hardisson, Francisco

    2017-09-15

    An extraction and determination method is shown for the analysis of dyes and solvents present in two types of ballpoint pen inks that are deposited onto paper. Ink extracts are analysed using a combination of gas chromatography with mass spectrometry (GC-MS), and high-pressure liquid chromatography with photodiode array detection (HPLC-DAD), within a single sample extraction procedure. Seventeen solvents and thirteen dyes contained in two Montblanc ® inks (black and blue) were monitored for 45 months at monthly intervals, in order to determine variations in the concentrations of the compounds over time. We also studied the relative variations between different compounds and the generation of degradation products such as phenol. The concentration data obtained from these compounds during their exposure have been analysed and a multiple regression model is developed for each ink type that allows an estimate of the exposure time of the ink on paper with a maximum error of between 4 and 7 months. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. [Simultaneous determination of five effective components in Sijunzi bolus using high performance liquid chromatography-evaporation light scattering detection].

    Science.gov (United States)

    Li, Chunying; Zhang, Xiaojun

    2010-01-01

    A high performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of lobetyolin, pachymic acid, glycyrrhizic acid, atractylenoide III and atractylenolide I in Sijunzi bolus. The separation was performed on an HIQ SIL C18 V column (250 mm x 4.6 mm, 5 microm) with 0.5% acetic acid-methanol as the mobile phase of gradient elution at a flow rate of 1.0 mL/min. The detection was performed with an evaporation light scattering detector (ELSD) and the sample volume was 10 microL. The temperature of drift tube and heating grade of nebulizer was respectively set at 55 degrees C and 60% at 0.2 MPa of pressure. Nitrogen gas was used as carrier gas. Under the optimized conditions, there were good linear relationships between the logarithm values of mass concentration and the peak areas of lobetyolin, pachymic acid, glycyrrhizic acid, atractylenoide III and atractylenolide I in the ranges of 0.076 - 1.21, 0.048 -0.76, 0.153 - 2.45, 0.045 - 0.72 and 0.098 - 1.56 g/L, respectively. The recoveries of the five components were between 97.13% and 100.25%, the relative standard deviations (RSDs) were between 1.23% and 2.44%. This method is simple, rapid, accurate and suitable for the quality control of Sijunzi bolus.

  19. Simultaneous Determination of Six Food Additives in drinks by high performance liquid chromatography coupled to diode array detector detection

    International Nuclear Information System (INIS)

    Yan, Q.

    2013-01-01

    A reversed-phase high performance liquid chromatographic method for the successful separation and determination of 6 synthetic food additives (aspartame, acesulfame potassium, benzoic acid, sodium saccharin, tartrazine and sunset yellow) was developed. A EclipseXDB-C18 column (250x4.6 mm I.D.; 5 micro m) was used and the mobile phase contained methanol and 0.02 mol/L ammonium acetate (pH 6.0) (30:70, v/v) was pumped at a flow rate of 0.7 mL/min at room temperature. Successful separation conditions were obtained for all the compounds using an optimized gradient elution within 10 min. The diode array detector was used to monitor the food additives at 230 nm. The method was thoroughly validated, detection limits for all substances varied between 0.03 and 1.35 micro g/mg, the intra-day precision (as RSD) ranged from 1.57% to 4.72 %, the inter-day precision (as RSD) was between 2.05 % and 4.18 %. Satisfactory recoveries, ranging from 90.00 % to 109.87 %, were obtained. The proposed system was applied to drink samples. (author)

  20. A novel analytical method of 1-(3-trifluoromethylphenyl piperazine and 1-(3-chlorophenyl piperazine in fluids of drug addicts using liquid-liquid extraction-gas chromatographic/nitrogen-phosphorous detection

    Directory of Open Access Journals (Sweden)

    Jing Chang

    2017-01-01

    Full Text Available In accordance with the research specifications and guidelines in China, we developed a novel experimental method to detect new piperazine-type drugs, such as 1-(3-trifluoromethylphenyl piperazine and 1-(3-chlorophenyl piperazine. In this study, a new pretreatment method and gas chromatography (GC/nitrogen-phosphorus detector detection technique were used to characterize these two kinds of drugs in urine and blood samples. For the purpose of isolation of these trace drugs from the samples, liquid-liquid extraction/solid-phase extraction was modified and validated for this specific study. The pretreatment method presented in this paper has many advantages, such as high recovery rate, high extraction efficiency, high detection sensitivity, low limit of detection, and simple operation. The GC/NPD instrument is popular in most laboratories because it can meet the routine requirements of forensic science. All these aspects make this combination of sample pretreatment and GC/NPD technique the most suitable choice for drug detection in biological samples.

  1. The composition of bile acids in patients with cholelithiasis according to the data of liquid chromatography with mass spectrometric detection

    Directory of Open Access Journals (Sweden)

    V. M. Klymenko

    2017-12-01

    Full Text Available Bile acids play a leading role in the physical and colloidal properties of bile stabilization. Lack of bile acids consequences result in the formation of cholesterol stones in the gall bladder, diarrhea and steatorrhea, fat-soluble vitamins impaired absorption, and kidney stones formation (oxalates. Investigation of altered bile composition, especially the content of bile acids, in patients with gallstone disease by means of modern analytical analysis methods (liquid chromatography with mass spectrometric detection would complement the modern ideas about mechanisms of lithogenesis and aim efforts at prevention of stone formation in the gall bladder, that was the purpose of our work. Materials and methods. Bile samples were tested for bile acid content using liquid chromatography with mass spectrometry. 14 samples of bile from patients with cholelithiasis were included in the main group, and control group consisted of 7 bile samples from practically healthy persons. Results. In patients with cholelithiasis there is an increase in the content of conjugated forms of bile acids – glycolic acid in 2 times (p = 0.002, taurocholic acid in 1.57 times (p = 0.062 compared with practically healthy persons. In patients with cholelithiasis, the ratio of taurocholic to glycolic acidі content (0.95 vs. 1.27, p = 0.0179, as well as glycogenodeoxycholic to glycodeoxycholic acid (1.11 vs. 1.58, p = 0.027 is significantly less than that in practically healthy persons. In addition, one in two patients with cholelithiasis does not reveal the presence of ursodeoxycholic acid in the bile. Conclusions. The lithogenic properties of bile are primarily caused by conjugated forms of cholic acid with glycine and taurine content violation. The ratio of taurocholic to glycolic acid content in patients with cholelithiasis is significantly lower than the similar index in practically healthy persons (0.95 vs. 1.27, p = 0.0179. The ratio of glycine conjugated bile acids

  2. Voltammetric behavior of nitrazepam and its determination in serum using liquid chromatography with redox mode dual-electrode detection.

    Science.gov (United States)

    Honeychurch, Kevin C; Smith, Gemma C; Hart, John P

    2006-01-15

    A method involving high-performance liquid chromatography with dual-electrode electrochemical detection in the redox mode (LC-DED) has been successfully developed for the determination of the benzodiazepine tranquilizer, nitrazepam, in serum. To elucidate the electrochemical mechanism occurring at a glassy carbon electrode, cyclic voltammetry was preformed with 1 mM solutions of nitrazepam at pH values between 2 and 12, using a potential range from -1.5 to +1.5 V. Two reduction peaks were observed over the whole pH range; the first, designated R1, was consistent with the 4e-, 4H+ reduction of the 7-nitro group to a hydroxylamine species; the second more negative peak, designated R2, was shown to be the result of a 2e-, 2H+ reduction of the 4-5 azomethine group. On the reverse anodic scan, an oxidation signal was observed, designated O1, which was considered to result from a 2e-, 2H+ oxidation of the hydroxylamine to a nitroso group. On the second forward scan, a new reduction peak, designated R3, was observed, which was considered to result from reduction of the nitroso species back to the hydroxylamine species. Studies were then undertaken to exploit the hydroxylamine/nitroso redox couple using LC-DED detection for the measurement of nitrazepam in serum. The optimal chromatographic conditions were found to comprise a mobile phase containing 60% methanol, 40% 50 mM pH 4.1 acetate buffer, in conjunction with a Hypersil C18 250 mm x 4.6 mm column. Hydrodynamic voltammetric studies were undertaken to optimize the operating potentials required for dual-electrode detection. It was found that an applied potential of -2.4 V was optimum for the "generator" cell and +0.5 V for the "detector" cell. The proposed method was evaluated by carrying out replicate nitrazepam determinations on spiked bovine and human serum samples. The former evaluation was preformed at a concentration of 11.2 microg mL(-1), and the latter at 1670 ng mL(-1). For bovine serum, the recovery of

  3. Determination of nine high-intensity sweeteners in various foods by high-performance liquid chromatography with mass spectrometric detection.

    Science.gov (United States)

    Zygler, Agata; Wasik, Andrzej; Kot-Wasik, Agata; Namieśnik, Jacek

    2011-06-01

    An analytical procedure involving solid-phase extraction (SPE) and high-performance liquid chromatography-mass spectrometry has been developed for the determination of nine high-intensity sweeteners authorised in the EU; acesulfame-K (ACS-K), aspartame (ASP), alitame (ALI), cyclamate (CYC), dulcin (DUL), neohesperidin dihydrochalcone (NHDC), neotame (NEO), saccharin (SAC) and sucralose (SCL) in a variety of food samples (i.e. beverages, dairy and fish products). After extraction with a buffer composed of formic acid and N,N-diisopropylethylamine at pH 4.5 in ultrasonic bath, extracts were cleaned up using Strata-X 33 μm Polymeric SPE column. The analytes were separated in gradient elution mode on C(18) column and detected by mass spectrometer working with an electrospray source in negative ion mode. To confirm that analytical method is suitable for its intended use, several validation parameters, such as linearity, limits of detection and quantification, trueness and repeatibilty were evaluated. Calibration curves were linear within a studied range of concentrations (r(2) ≥ 0.999) for six investigated sweeteners (CYC, ASP, ALI, DUL, NHDC, NEO). Three compounds (ACS-K, SAC, SCL) gave non-linear response in the investigated concentration range. The method detection limits (corresponding to signal-to-noise (S/N) ratio of 3) were below 0.25 μg mL(-1) (μg g(-1)), whereas the method quantitation limits (corresponding to S/N ratio of 10) were below 2.5 μg mL(-1) (μg g(-1)). The recoveries at the tested concentrations (50%, 100% and 125% of maximum usable dose) for all sweeteners were in the range of 84.2 ÷ 106.7%, with relative standard deviations beverage, yoghurt, fish product) and the spiking level. The proposed method has been successfully applied to the determination of the nine sweeteners in drinks, yoghurts and fish products. The procedure described here is simple, accurate and precise and is suitable for routine quality control analysis of

  4. Analysis and quantification of parabens in cosmetic products by utilizing hollow fibre-supported liquid membrane and high performance liquid chromatography with ultraviolet detection.

    Science.gov (United States)

    Msagati, T A M; Barri, T; Larsson, N; Jönsson, J A

    2008-08-01

    A simple and direct method based on hollow fibre-supported liquid membrane (HFSLM) extraction and liquid chromatography equipped with a UV detector was developed for analysis and quantification of parabens in cosmetic products. The parabens analysed included methyl, ethyl, propyl, isobutyl and butyl paraben. The HFSLM extraction was carried out by employing di-n-hexyl ether as organic liquid that was immobilized in the hollow fibre membrane. The HFSLM extraction is simple, cheap, minimizes the use of solvents and uses disposable material. In an investigation of 11 paraben-containing cosmetic products, the levels of parabens (sum of all parabens in a product) ranged from 0.43% to 0.79% (w/w) for skin care products, 0.07-0.44% for hair fixing gels and 0.30-0.52% for soap solutions. The levels of individual parabens in individual cosmetic products ranged between 0.03% and 0.42% w/w for skin care products, 0.07% and 0.26% w/w for hair fixing gels and between 0.11% and 0.34% w/w for soap solutions. Parabens were found in the highest concentrations in skin care products followed by soap solutions and the least amounts were found in hair fixing gels. Of the paraben-containing products tested, all of them contained methyl paraben and about 90% contained propyl paraben in addition to methyl paraben. One product contained all the parabens analysed.

  5. Detection of chemical substances in water using an oxide nanowire transistor covered with a hydrophobic nanoparticle thin film as a liquid-vapour separation filter

    Directory of Open Access Journals (Sweden)

    Taekyung Lim

    2016-08-01

    Full Text Available We have developed a method to detect the presence of small amounts of chemical substances in water, using a Al2O3 nanoparticle thin film covered with phosphonic acid (HDF-PA self-assembled monolayer. The HDF-PA self-assembled Al2O3 nanoparticle thin film acts as a liquid-vapour separation filter, allowing the passage of chemical vapour while blocking liquids. Prevention of the liquid from contacting the SnO2 nanowire and source-drain electrodes is required in order to avoid abnormal operation. Using this characteristic, the concentration of chemical substances in water could be evaluated by measuring the current changes in the SnO2 nanowire transistor covered with the HDF-PA self-assembled Al2O3 nanoparticle thin film.

  6. Plasma erosion switch

    International Nuclear Information System (INIS)

    Mendel, C.W. Jr.; Goldstein, S.A.; Miller, P.A.

    1976-01-01

    The plasma erosion switch is a device capable of initially carrying high currents, and then of opening in nanoseconds to stand off high voltages. It depends upon the erosion of a plasma which initially fills the switch. The sheath between the plasma and the cathode behaves as a diode with a rapidly increasing A-K gap. Preliminary tests of the switch on the Proto I accelerator at Sandia will be described. In these tests, the switch consisted of a cylinder of highly ionized plasma four inches in diameter and one-inch thick surrounding a one-inch cathode. The switch shorted out prepulse voltages and allowed energy to be stored in the diode inductance outside the switch until the accelerator current reached 75 kA. The switch impedance then rose rapidly to approximately 100 ω in 5 nanoseconds, whereupon the accelerator current transferred to the cathode. Current rise rates of 3.10 13 A/sec were limited by cathode turn-on. Voltage rise rates of 10 15 V/sec were achieved. The elimination of prepulse and machine turn-on transients allowed A-K gaps of 2 mm to be used with 2.5 MV pulses, yielding average E fields of 12 MV/cm. Staged versions of the device are being built and should improve rise rates. The switch shows promise for use with future, higher power, lower inductance machines

  7. Switched reluctance motor drives

    Indian Academy of Sciences (India)

    Davis RM, Ray WF, Blake RJ 1981 Inverter drive for switched reluctance: circuits and component ratings. Inst. Elec. Eng. Proc. B128: 126-136. Ehsani M. 1991 Position Sensor elimination technique for the switched reluctance motor drive. US Patent No. 5,072,166. Ehsani M, Ramani K R 1993 Direct control strategies based ...

  8. A study on a real-time leak detection method for pressurized liquid refrigerant pipeline based on pressure and flow rate

    International Nuclear Information System (INIS)

    Tian, Shen; Du, Juanli; Shao, Shuangquan; Xu, Hongbo; Tian, Changqing

    2016-01-01

    Highlights: • A real-time leak detection method is developed for ammonia pipeline in cold storage. • A locating algorithm based on pressure difference profile is provided. • This method is validated by R22 and ammonia leak experiments. • The minimum detectable leak ratio is 1% for R22 and 4% for ammonia. • The location estimating errors are −27% ~ 17% for R22 and −27% ~ 27% for ammonia. - Graphical Abstract: - Abstract: Leakage from pressurized liquid ammonia pipeline has been a serious problem in large commercial cold storages because it might release large amount of liquid ammonia and without safety supervision in daily operations. The present paper shows a detection method for a pressurized liquid ammonia pipeline with a leak. The variations of pressure, flow rate and pressure difference profile are studied. A leak indicator (σ), proposed with the one-dimensional steady-state flow model, is used to detect the leak occurrence by comparing it with a threshold value (σ Le ). A locating algorithm based on pressure difference profile along the pipeline is also proposed, which has considered the effect of the static pressure increase at the leak point. Experiments on different leak positions and ratios from liquid R22 and ammonia pipelines are carried out to validate this method. It is found that, with a relatively low false alarm rate (as three percent), the minimum detectable leak ratio reached 1% for the R22 pipeline and 4% for the ammonia pipeline. The locating errors are between −27% ~ 17% for R22 pipeline and −27% ~ 27% for ammonia pipeline.

  9. [Detection of human papilloma virus (HPV) in liquid-based cervical samples. Correlation with protein p16INK4a expression].

    Science.gov (United States)

    Toro de Méndez, Morelva; Ferrández Izquierdo, Antonio

    2011-03-01

    The liquid-based cervical cytology improves the quality of the sample and the residual sample could be used efficiently to carry out complementary tests, such as the detection of HPV DNA and the immunocytochemical biomarkers study. The purpose of this study was to correlate the presence of HPV and immunoexpression of p16INK4a in liquid-based cervical samples to examine the utility of these new tools in the detection of cervical cancer. The included patients (n = 67) presented an abnormal cytology or previous cervical pathology. The HPV detection and genotyping were carried out with PCR-SPF10/LiPA (INNOLiPA Extra Amp) and for p16INK4a immunodetection was used antibody clone E6H4. The conventional cytology provided the same cytologic interpretations that those of liquid-based cytology. The overall HPV prevalence was 43.3% (29/67). HPV16 was the most frequent viral type (31.03%) and 48.3% of the cases were infected with multiple HPV types. p16INK4a immunoexpression was observed in 35.8% of liquid-based cytological samples and this was significantly (p < 0.020) associated to the HPV presence. These results support the evidence that the implementation of new technologies in the daily routine of the laboratory, contribute significantly in the early detection of cervical cancer and provide important data to help in the patient's efficient management. The combined use of HPV detection and p16INK4a expression could be used for evaluation of patients with more risk to develop significant cervical lesions.

  10. Switch on, switch off: stiction in nanoelectromechanical switches

    KAUST Repository

    Wagner, Till J W

    2013-06-13

    We present a theoretical investigation of stiction in nanoscale electromechanical contact switches. We develop a mathematical model to describe the deflection of a cantilever beam in response to both electrostatic and van der Waals forces. Particular focus is given to the question of whether adhesive van der Waals forces cause the cantilever to remain in the \\'ON\\' state even when the electrostatic forces are removed. In contrast to previous studies, our theory accounts for deflections with large slopes (i.e. geometrically nonlinear). We solve the resulting equations numerically to study how a cantilever beam adheres to a rigid electrode: transitions between \\'free\\', \\'pinned\\' and \\'clamped\\' states are shown to be discontinuous and to exhibit significant hysteresis. Our findings are compared to previous results from linearized models and the implications for nanoelectromechanical cantilever switch design are discussed. © 2013 IOP Publishing Ltd.

  11. Analysis of Levodopa Content in Commercial Mucuna pruriens Products Using High-Performance Liquid Chromatography with Fluorescence Detection.

    Science.gov (United States)

    Soumyanath, Amala; Denne, Tanya; Hiller, Amie; Ramachandran, Shaila; Shinto, Lynne

    2018-02-01

    Mucuna pruriens (MP) seeds contain levodopa (up to 2% by weight) and have been used in traditional Indian medicine to treat an illness named "Kampavata," now understood to be Parkinson's disease (PD). Studies have shown MP to be beneficial, and even superior, to levodopa alone in treating PD symptoms. Commercial products containing MP are readily available from online and retail sources to patients and physicians. Products often contain extracts of MP seeds, with significantly higher levodopa content than the seeds. However, MP products have limited regulatory controls with respect to quality and content of active ingredient. The aim of this study was to apply a quantitative method to determine levodopa content in readily available MP products that might be used by patients or in research studies. Levodopa present in six commercial MP products was quantified by solvent extraction followed by reversed-phase high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FD). Certificates of analysis (COA) were obtained, from manufacturers of MP products, to assess the existence and implementation of specifications for levodopa content. HPLC-FD analysis revealed that the levodopa content of the six commercial MP products varied from 6% to 141% of individual label claims. No product contained levodopa within normal pharmacopeial limits of 90%-110% label claim. The maximum daily dose of levodopa delivered by the products varied from 14.4 to 720 mg/day. COAs were inconsistent in specifications for and verification of levodopa content. The commercial products tested varied widely in levodopa content, sometimes deviating widely from the label claim. These deficiencies could impact efficacy and safety of MP products used by PD patients and compromise the results of scientific studies on MP products. The HPLC-FD method described in this study could be utilized by both manufacturers and scientific researchers to verify levodopa content of MP products.

  12. Microwave plasma torch mass spectrometry for the direct detection of copper and molybdenum ions in aqueous liquids.

    Science.gov (United States)

    Xiong, Xiaohong; Jiang, Tao; Zhou, Runzhi; Wang, Shangxian; Zou, Wei; Zhu, Zhiqiang

    2016-05-01

    Microwave plasma torch (MPT) is a simple and low power-consumption ambient ion source. And the MPT Mass spectra of many metal elements usually exhibit some novel features different from their inductively coupled plasma (ICP) mass spectra, which may be helpful for metal element analysis. Here, we presented the results about the MPT mass spectra of copper and molybdenum elements by a linear ion trap mass spectrometer (LTQ). The generated copper or molybdenum contained ions in plasma were characterized further in collision-induced dissociated (CID) experiments. These researches built a novel, direct and sensitive method for the direct analysis of trace levels of copper and molybdenum in aqueous liquids. Quantitative results showed that the limit of detection (LOD) by using MS(2) procedure was estimated to be 0.265 µg/l (ppb) for copper and 0.497 µg/l for molybdenum. The linear dynamics ranges cover at least 2 orders of magnitude and the analysis of a single aqueous sample can be completed in 5-6 min with a reasonable semi-quantitative sense. Two practical aqueous samples, milk and urine, were also analyzed qualitatively with reasonable recovery rates and RSD. These experimental data demonstrated that the MPT MS is able to turn into a promising and hopeful tool in field analysis of copper and molybdenum ions in water and some aqueous media, and can be applied in many fields, such as environmental controlling, hydrogeology, and water quality inspection. Moreover, MPT MS could also be used as the supplement of ICP-MS for the rapid and in-situ analysis of metal ions. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Determination of cilnidipine, a new calcium antagonist, in human plasma using high performance liquid chromatography with tandem mass spectrometric detection.

    Science.gov (United States)

    Zhang, Xianhua; Zhai, Suodi; Zhao, Rongsheng; Ouyang, Jin; Li, Xiaoguang; Baeyens, Willy R G

    2007-09-26

    A rapid, sensitive and reliable high performance liquid chromatographic method coupled with tandem mass spectrometry (HPLC-MS/MS) has been developed and validated for the determination of cilnidipine, a relatively new calcium antagonist, in human plasma. The reversed-phase chromatographic system was interfaced with a TurboIonSpray (TIS) source. Nimodipine was employed as the internal standard (IS). Sample extracts following protein precipitation were injected into the HPLC-MS/MS system. The analyte and IS were eluted isocratically on a C18 column, with a mobile phase consisting of CH(3)OH and NH(4)Ac (96:4, v/v). The ions were detected by a triple quadrupole mass spectrometric detector in the negative mode. Quantification was performed using multiple reaction monitoring (MRM) of the transitions m/z 491.2-->122.1 and m/z 417.1-->122.1 for cilnidipine and for the IS, respectively. The analysis time for each run was 3.0 min. The calibration curve fitted well over the concentration range of 0.1-10 ngmL(-1), with the regression equation Y=(0.103+/-0.002)X+(0.014+/-0.003) (n=5), r=0.9994. The intra-day and inter-day R.S.D.% were less than 12.51% at all concentration levels within the calibration range. The recoveries were between 92.71% and 97.64%. The long-term stability and freeze-thaw stability were satisfying at each level. The present method provides a modern, rapid and robust tool for pharmacokinetic studies of cilnidipine.

  14. Determination of Propionylbrassinolide and Its Impurities by High-Performance Liquid Chromatography with Evaporative Light Scattering Detection

    Directory of Open Access Journals (Sweden)

    Lidong Cao

    2018-02-01

    Full Text Available The discovery of brassinolide in 1979, a milestone in brassinosteroids research, has sparked great interest of brassinolide analogs (BLs in agricultural applications. Among these BLs, propionylbrassinolide has captured considerable attention because it shows plant growth regulating activity with an excellent durability. Two impurities of propionylbrassinolide were isolated and purified by semi-preparative high-performance liquid chromatography (HPLC, and the chemical structures were confirmed. For simultaneous separation and determination of propionylbrassinolide and impurities, an efficient analytical method based on HPLC with evaporative light scattering detector (HPLC-ELSD was developed. The optimized analysis was performed on a C18 reversed phase column (250 mm × 4.60 mm, 5 μm with isocratic elution of acetonitrile and water (90:10, v/v as the mobile phase. The drift tube temperature of the ELSD system was set to 50 °C and the auxiliary gas pressure was 150 kPa. The regression equations demonstrated a good linear relationship (R2 = 0.9989–0.9999 within the test ranges. The limits of detection (LODs and quantification (LOQs for propionylbrassinolide, impurity 1 and 2 were 1.3, 1.2, 1,3 and 4.3, 4.0, 4.2 mg/L, respectively. The fully validated HPLC-ELSD method was readily applied to quantify the active ingredient and impurities in propionylbrassinolide technical concentrate. Moreover, the optimized separation conditions with ELSD have been successfully transferred to mass spectrometry (MS detector for LC-MS determination.

  15. An analytical method for determination of fullerenes and functionalized fullerenes in soils with high performance liquid chromatography and UV detection

    International Nuclear Information System (INIS)

    Carboni, Andrea; Emke, Erik; Parsons, John R.; Kalbitz, Karsten; Voogt, Pim de

    2014-01-01

    Graphical abstract: -- Highlights: •A total of eight fullerenes can be analyzed in a single run with HPLC-UV. •The method allows the analysis of fullerenes in soil at relatively low concentrations. •The method developed is robust, highly reproducible and relatively efficient. •The method can be applied to the study of the environmental fate and toxicology of fullerenes. -- Abstract: Fullerenes are carbon-based nanomaterials expected to play a major role in emerging nanotechnology and produced at an increasing rate for industrial and household applications. In the last decade a number of novel compounds (i.e. fullerene derivatives) is being introduced into the market and specific analytical methods are needed for analytical purposes as well as environmental and safety issues. In the present work eight fullerenes (C60 and C70) and functionalized fullerenes (C60 and C70 exohedral-derivatives) were selected and a novel liquid chromatographic method was developed for their analysis with UV absorption as a method of detection. The resulting HPLC-UV method is the first one suitable for the analysis of all eight compounds. This method was applied for the analysis of fullerenes added to clayish, sandy and loess top-soils at concentrations of 20, 10 and 5 μg kg −1 and extracted with a combination of sonication and shaking extraction. The analytical method limits of detection (LoD) and limits of quantification (LoQ) were in the range of 6–10 μg L −1 and 15–24 μg L −1 respectively for the analytical solutions. The extraction from soil was highly reproducible with recoveries ranging from 47 ± 5 to 71 ± 4% whereas LoD and LoQ for all soils tested were of 3 μg kg −1 and 10 μg kg −1 respectively. No significant difference in the extraction performance was observed depending of the different soil matrices and between the different concentrations. The developed method can be applied for the study of the fate and toxicity of fullerenes in complex matrices

  16. Phytochemical and morphological characterization of hop (Humulus lupulus L.) cones over five developmental stages using high performance liquid chromatography coupled to time-of-flight mass spectrometry, ultrahigh performance liquid chromatography photodiode array detection, and light microscopy techniques.

    Science.gov (United States)

    Kavalier, Adam R; Litt, Amy; Ma, Chunhui; Pitra, Nicholi J; Coles, Mark C; Kennelly, Edward J; Matthews, Paul D

    2011-05-11

    Hop (Humulus lupulus L.) inflorescences, commonly known as "hop cones", are prized for their terpenophenolic contents, used in beer production and, more recently, in biomedical applications. In this study we investigated morphological and phytochemical characteristics of hop cones over five developmental stages, using liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF-MS), and ultrahigh performance liquid chromatography photodiode array detection (UHPLC-PDA) methods to quantitate 21 polyphenolics and seven terpenophenolics. Additionally, we used light microscopy to correlate phytochemical quantities with changes in the morphology of the cones. Significant increases in terpenophenolics, concomitant with glandular trichome development and associated gross morphological changes, were mapped over development to fluctuations in contents of polyphenolic constituents and their metabolic precursor compounds. The methods reported here can be used for targeted metabolic profiling of flavonoids, phenolic acids, and terpenophenolics in hops, and are applicable to quantitation in other crops.

  17. Optimization of biological and instrumental detection of explosives and ignitable liquid residues including canines, SPME/ITMS and GC/MSn

    Science.gov (United States)

    Furton, Kenneth G.; Harper, Ross J.; Perr, Jeannette M.; Almirall, Jose R.

    2003-09-01

    A comprehensive study and comparison is underway using biological detectors and instrumental methods for the rapid detection of ignitable liquid residues (ILR) and high explosives. Headspace solid phase microextraction (SPME) has been demonstrated to be an effective sampling method helping to identify active odor signature chemicals used by detector dogs to locate forensic specimens as well as a rapid pre-concentration technique prior to instrumental detection. Common ignitable liquids and common military and industrial explosives have been studied including trinitrotoluene, tetryl, RDX, HMX, EGDN, PETN and nitroglycerine. This study focuses on identifying volatile odor signature chemicals present, which can be used to enhance the level and reliability of detection of ILR and explosives by canines and instrumental methods. While most instrumental methods currently in use focus on particles and on parent organic compounds, which are often involatile, characteristic volatile organics are generally also present and can be exploited to enhance detection particularly for well-concealed devices. Specific examples include the volatile odor chemicals 2-ethyl-1-hexanol and cyclohexanone, which are readily available in the headspace of the high explosive composition C-4; whereas, the active chemical cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) is not. The analysis and identification of these headspace 'fingerprint' organics is followed by double-blind dog trials of the individual components using certified teams in an attempt to isolate and understand the target compounds to which dogs are sensitive. Studies to compare commonly used training aids with the actual target explosive have also been undertaken to determine their suitability and effectiveness. The optimization of solid phase microextraction (SPME) combined with ion trap mobility spectrometry (ITMS) and gas chromatography/mass spectrometry/mass spectrometry (GC/MSn) is detailed including interface development

  18. Quality assessment of crude and processed ginger by high-performance liquid chromatography with diode array detection and mass spectrometry combined with chemometrics.

    Science.gov (United States)

    Deng, Xianmei; Yu, Jiangyong; Zhao, Ming; Zhao, Bin; Xue, Xingyang; Che, ChunTao; Meng, Jiang; Wang, Shumei

    2015-09-01

    A sensitive, simple, and validated high-performance liquid chromatography with diode array detection and mass spectrometry detection method was developed for three ginger-based traditional Chinese herbal drugs, Zingiberis Rhizoma, Zingiberis Rhizome Preparatum, and Zingiberis Rhizome Carbonisata. Chemometrics methods, such as principal component analysis, hierarchical cluster analysis, and analysis of variance, were also employed in the data analysis. The results clearly revealed significant differences among Zingiberis Rhizoma, Zingiberis Rhizome Preparatum, and Zingiberis Rhizome Carbonisata, indicating variations in their chemical compositions during the processing, which may elucidate the relationship of the thermal treatment with the change of the constituents and interpret their different clinical uses. Furthermore, the sample consistency of Zingiberis Rhizoma, Zingiberis Rhizome Preparatum, and Zingiberis Rhizome Carbonisata can also be visualized by high-performance liquid chromatography with diode array detection and mass spectrometry analysis followed by principal component analysis/hierarchical cluster analysis. The comprehensive strategy of liquid chromatography with mass spectrometry analysis coupled with chemometrics should be useful in quality assurance for ginger-based herbal drugs and other herbal medicines. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Classification of the medicinal plants of the genus Atractylodes using high-performance liquid chromatography with diode array and tandem mass spectrometry detection combined with multivariate statistical analysis.

    Science.gov (United States)

    Cho, Hyun-Deok; Kim, Unyong; Suh, Joon Hyuk; Eom, Han Young; Kim, Junghyun; Lee, Seul Gi; Choi, Yong Seok; Han, Sang Beom

    2016-04-01

    Analytical methods using high-performance liquid chromatography with diode array and tandem mass spectrometry detection were developed for the discrimination of the rhizomes of four Atractylodes medicinal plants: A. japonica, A. macrocephala, A. chinensis, and A. lancea. A quantitative study was performed, selecting five bioactive components, including atractylenolide I, II, III, eudesma-4(14),7(11)-dien-8-one and atractylodin, on twenty-six Atractylodes samples of various origins. Sample extraction was optimized to sonication with 80% methanol for 40 min at room temperature. High-performance liquid chromatography with diode array detection was established using a C18 column with a water/acetonitrile gradient system at a flow rate of 1.0 mL/min, and the detection wavelength was set at 236 nm. Liquid chromatography with tandem mass spectrometry was applied to certify the reliability of the quantitative results. The developed methods were validated by ensuring specificity, linearity, limit of quantification, accuracy, precision, recovery, robustness, and stability. Results showed that cangzhu contained higher amounts of atractylenolide I and atractylodin than baizhu, and especially atractylodin contents showed the greatest variation between baizhu and cangzhu. Multivariate statistical analysis, such as principal component analysis and hierarchical cluster analysis, were also employed for further classification of the Atractylodes plants. The established method was suitable for quality control of the Atractylodes plants. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Characterisation of acid dyes in forensic fibre analysis by high-performance liquid chromatography using narrow-bore columns and diode array detection.

    Science.gov (United States)

    Laing, D K; Gill, R; Blacklaws, C; Bickley, H M

    1988-06-17

    A gradient elution high-performance liquid chromatographic (HPLC) system with a diode array detector and a short narrow-bore (40 x 1 mm I.D.) column has been used to characterise a number of acid dyes. The resolution and reproducibility of the HPLC system have been evaluated and the detection limits for various dyes have been estimated. Comparisons are made with current methods of fibre dyestuff examination used in forensic science. The system has been applied to the analysis of dye extracted from single fibres. Using diode array detection, both chromatographic and spectral data can be produced in a single operation from casework sized samples.

  1. Switch mode power supply

    International Nuclear Information System (INIS)

    Kim, Hui Jun

    1993-06-01

    This book concentrates on switch mode power supply. It has four parts, which are introduction of switch mode power supply with DC-DC converter such as Buck converter boost converter, Buck-boost converter and PWM control circuit, explanation for SMPS with DC-DC converter modeling and power mode control, resonance converter like resonance switch, converter, multi resonance converter and series resonance and parallel resonance converters, basic test of SMPS with PWM control circuit, Buck converter, Boost converter, flyback converter, forward converter and IC for control circuit.

  2. BROOKHAVEN: Switched power

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Hosted by Brookhaven's Center for Accelerator Physics, a recent workshop on switched power techniques attracted a group of specialists to Shelter Island, New York, location of several important physics meetings, including the famous 1947 sessions which helped mould modern quantum electrodynamics. The current interest in switched power stemmed from a series of papers by W. Willis of CERN, starting in 1984. The idea is for stored electrical energy to be suddenly switched on to a transmission line, producing a very short (about 10 ps) electromagnetic pulse in a region traversed by a particle beam

  3. Electromechanical magnetization switching

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Eugene M. [Department of Physics and Astronomy, Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Jaafar, Reem [Department of Mathematics, Engineering and Computer Science, LaGuardia Community College, The City University of New York, 31-10 Thomson Avenue, Long Island City, New York 11101 (United States)

    2015-03-14

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.

  4. Electromechanical magnetization switching

    International Nuclear Information System (INIS)

    Chudnovsky, Eugene M.; Jaafar, Reem

    2015-01-01

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained

  5. JUNOS Enterprise Switching

    CERN Document Server

    Reynolds, Harry

    2009-01-01

    JUNOS Enterprise Switching is the only detailed technical book on Juniper Networks' new Ethernet-switching EX product platform. With this book, you'll learn all about the hardware and ASIC design prowess of the EX platform, as well as the JUNOS Software that powers it. Not only is this extremely practical book a useful, hands-on manual to the EX platform, it also makes an excellent study guide for certification exams in the JNTCP enterprise tracks. The authors have based JUNOS Enterprise Switching on their own Juniper training practices and programs, as well as the configuration, maintenanc

  6. Microfluidic immunosensor with integrated liquid core waveguides for sensitive Mie scattering detection of avian influenza antigens in a real biological matrix.

    Science.gov (United States)

    Heinze, Brian C; Gamboa, Jessica R; Kim, Keesung; Song, Jae-Young; Yoon, Jeong-Yeol

    2010-11-01

    This work presents the use of integrated, liquid core, optical waveguides for measuring immunoagglutination-induced light scattering in a microfluidic device, towards rapid and sensitive detection of avian influenza (AI) viral antigens in a real biological matrix (chicken feces). Mie scattering simulations were performed and tested to optimize the scattering efficiency of the device through proper scatter angle waveguide geometry. The detection limit is demonstrated to be 1 pg mL(-1) in both clean buffer and real biological matrix. This low detection limit is made possible through on-chip diffusional mixing of AI target antigens and high acid content microparticle assay reagents, coupled with real-time monitoring of immunoagglutination-induced forward Mie scattering via high refractive index liquid core optical waveguides in close proximity (100 μm) to the sample chamber. The detection time for the assay is <2 min. This device could easily be modified to detect trace levels of any biological molecules that antibodies are available for, moving towards a robust platform for point-of-care disease diagnostics.

  7. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  8. Detection of anabolic and androgenic steroids and/or their esters in horse hair using ultra-high performance liquid chromatography-high resolution mass spectrometry.

    Science.gov (United States)

    Kwok, Karen Y; Choi, Timmy L S; Kwok, Wai Him; Wong, Jenny K Y; Wan, Terence S M

    2017-04-14

    Anabolic and androgenic steroids (AASs) are a class of prohibited substances banned in horseracing at all times. The common approach for controlling the misuse of AASs in equine sports is by detecting the presence of AASs and/or their metabolites in urine and blood samples using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). This approach, however, often falls short as the duration of effect for many AASs are longer than their detection time in both urine and blood. As a result, there is a high risk that such AASs could escape detection in their official race-day samples although they may have been used during the long period of training. Hair analysis, on the other hand, can afford significantly longer detection windows. In addition, the identification of synthetic ester derivatives of AASs in hair, particularly for the endogenous ones, can provide unequivocal proof of their exogenous origin. This paper describes the development of a sensitive method (at sub to low parts-per-billion or ppb levels) for detecting 48 AASs and/or their esters in horse hair using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS). Decontaminated horse hair was pulverised and subjected to in-situ liquid-liquid extraction in a mixture of hexane - ethyl acetate (7:3, v/v) and phosphate buffer (0.1M, pH 9.5), followed by additional clean-up using mixed-mode solid-phase extraction. The final extract was analysed using UHPLC-HRMS in the positive electrospray ionisation (ESI) mode with both full scan and parallel reaction monitoring (PRM). This method was validated for qualitative identification purposes. Validation data, including method specificity, method sensitivity, extraction recovery, method precision and matrix effect are presented. Method applicability was demonstrated by the successful detection and confirmation of testosterone propionate in a referee hair sample. To our knowledge, this was

  9. New Photonic System for Optical Packet Switching

    Directory of Open Access Journals (Sweden)

    F. Rudge Barbosa

    2003-08-01

    Full Text Available Fast optical switching (ms timebase is realized by using a RF frequency tone inserted in the optical packet that carries a digital payload. By using a highly selective RF filtering for optical packet header frequency recognition, we have obtained excellent performance in optical switching function.. The RF header is detected at optical node input, and signals the node switching control, which instantly directs the packet to a prescribed output. No electronic processing of the digital payload is performed. The optical circuit is noise-free, has very low crosstalk, and is extremely selective in header frequency detection. BER measurements for payload consistently yield figures as low as 10-12 . This system is applicable to optical metropolitan and access networks, and is fully compatible with DWDM systems.

  10. Advances in ultra-high performance liquid chromatography coupled to tandem mass spectrometry for sensitive detection of several food allergens in complex and processed foodstuffs.

    Science.gov (United States)

    Planque, M; Arnould, T; Dieu, M; Delahaut, P; Renard, P; Gillard, N

    2016-09-16

    Sensitive detection of food allergens is affected by food processing and foodstuff complexity. It is therefore a challenge to detect cross-contamination in food production that could endanger an allergic customer's life. Here we used ultra-high performance liquid chromatography coupled to tandem mass spectrometry for simultaneous detection of traces of milk (casein, whey protein), egg (yolk, white), soybean, and peanut allergens in different complex and/or heat-processed foodstuffs. The method is based on a single protocol (extraction, trypsin digestion, and purification) applicable to the different tested foodstuffs: chocolate, ice cream, tomato sauce, and processed cookies. The determined limits of quantitation, expressed in total milk, egg, peanut, or soy proteins (and not soluble proteins) per kilogram of food, are: 0.5mg/kg for milk (detection of caseins), 5mg/kg for milk (detection of whey), 2.5mg/kg for peanut, 5mg/kg for soy, 3.4mg/kg for egg (detection of egg white), and 30.8mg/kg for egg (detection of egg yolk). The main advantage is the ability of the method to detect four major food allergens simultaneously in processed and complex matrices with very high sensitivity and specificity. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Sensitive immunoassay-based detection of Vibrio parahaemolyticus using capture and labeling particles in a stationary liquid phase lab-on-a-chip.

    Science.gov (United States)

    Park, Byunghee; Choi, Suk-Jung

    2017-04-15

    In the present study, a method was developed for detection of Vibrio parahaemolyticus based on a stationary liquid phase lab-on-a-chip (SLP LOC). The present SLP LOC comprises a sample chamber, washing chamber, and detection chamber connected by two channels. The method utilizes two types of particles: capture particles (CPs), which are magnetic nanoparticles functionalized with antibody; and labeling particles (LPs), which are silica nanoparticles functionalized with horseradish peroxidase and antibody. Samples were added to the sample chamber with CPs and LPs, forming a CP-bacteria-LP complex, and the complex was transported to the detection chamber containing chromogenic substrate solution. The method allowed the detection of V. parahaemolyticus in the range of 10 1 -10 5 cfu within 45min. Additionally, contamination of oyster samples with V. parahaemolyticus was detected within 2.5h, including 2h of culturing. The present method has the advantage of being highly rapid and facile, and enabling the detection of bacteria with high sensitivity. Moreover, the LOC and LOC processing device used in this method possess simple structures, making the detection process economical and allowing miniaturization. Therefore, the present SLP LOC detection method is potentially useful for in situ determination of food safety. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. uv preilluminated gas switches

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-06-03

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10/sup 12/ amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters.

  13. Switching power supply filter

    Science.gov (United States)

    Kumar, Prithvi R. (Inventor); Abare, Wayne (Inventor)

    1989-01-01

    A filter for a switching power supply. The filter includes a common mode inductor with coil configurations allowing differential mode current from a dc source to pass through but attenuating common mode noise from the power supply so that the noise does not reach the dc source. The invention also includes the use of feed through capacitors at the switching power supply input terminals to provide further high-frequency noise attenuation.

  14. uv preilluminated gas switches

    International Nuclear Information System (INIS)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-01-01

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10 12 amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters

  15. Photonics in switching

    CERN Document Server

    Midwinter, John E; Kelley, Paul

    1993-01-01

    Photonics in Switching provides a broad, balanced overview of the use of optics or photonics in switching, from materials and devices to system architecture. The chapters, each written by an expert in the field, survey the key technologies, setting them in context and highlighting their benefits and possible applications. This book is a valuable resource for those working in the communications industry, either at the professional or student level, who do not have extensive background knowledge or the underlying physics of the technology.

  16. A study on switched linear system identification using game ...

    African Journals Online (AJOL)

    This study deals with application of game-theoretic strategies and neural computing to switched linear system identification, wherein some of the subsystems may be in failed, standby, or working states. The controller is to detect failed subsystems, and switch standby and working subsystems to maintain stable system ...

  17. Progress in switching technology for METS systems

    International Nuclear Information System (INIS)

    Honig, E.M.; Swannack, C.E.; Warren, R.W.; Whitaker, D.H.

    1977-01-01

    Three distinct sets of switching requirements have emerged from design optimization studies of large superconducting magnetic energy storage systems, such as the METS system to power the adiabatic plasma compression field in the proposed theta-pinch SFTR. Extremely low joule loss cryogenic disconnects are required between storage coils in the liquid helium environment to allow charging the coils in series over a prolonged time, then to isolate the coils for parallel fast discharging into the load. Another switch must break the current in the series charging loop and absorb the energy from the stray inductance. This action will allow the subsequent opening of the cryogenic disconnects under near zero current condition. The current now has been transferred to the many paralleled circuits, each containing a high current, high voltage interrupter. The opening and arc commutation of the interrupter starts the energy transfer into the load. The primary activities associated with cryogenic disconnect have been testing and development of contact materials, configurations, and closing forces for carrying 26 kA with a resistance less than 40 nΩ, and development of an actuating system that is both reliable and fast acting in a liquid helium environment. The charging loop switch will include a continuous duty switch and a vacuum interrupter. The continuous duty switch resistance can be an order of magnitude larger than that of the cryogenic disconnect because it does not present a refrigeration load. The HVDC interrupter must break 26 kA and withstand 60 kV during the energy transfer time of 700 μs. Testing in progress already has shown successful interruption using single vacuum interrupters up to 31 kA and 66 kV

  18. Optical switching systems using nanostructures

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2004-01-01

    High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems.......High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems....

  19. Understanding and Supporting Window Switching

    NARCIS (Netherlands)

    Tak, S.

    2011-01-01

    Switching between windows on a computer is a frequent activity, but finding and switching to the target window can be inefficient. This thesis aims to better un-derstand and support window switching. It explores two issues: (1) the lack of knowledge of how people currently interact with and switch

  20. Application of sugaring-out extraction for the determination of sulfonamides in honey by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Tsai, Wen-Hsien; Chuang, Hung-Yi; Chen, Ho-Hsien; Wu, Yuh-Wern; Cheng, Shou-Hsun; Huang, Tzou-Chi

    2010-12-03

    A simple sugaring-out assisted liquid-liquid extraction method combined with high-performance liquid-chromatography with fluorescence detection (HPLC-FL) was developed for the extraction and determination of sulfonamides in honey. Sample preparation consisted of acid hydrolysis to release sugar-bound sulfonamides. After derivatization with fluorescamine, the derivatives were partitioned into the organic layer under the honey (sugar)/water/acetonitrile system. The clear organic extract obtained by centrifugation could be injected into the HPLC system either directly or after dilution. Linearity was obtained with the coefficient of determination (R(2)) higher than 0.998 from 2 to 200 ng/mL. Under the optimal conditions, recoveries were determined for honey fortified at three levels (5, 20, and 100 ng/g) were 80.9-99.6% with coefficients of variation of 0.3-4.4%. Limits of detection for the sulfonamides studied were found to range from 0.6 to 0.9 ng/g. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Low inductance gas switching.

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  2. Parallel microscope-based fluorescence, absorbance and time-of-flight mass spectrometry detection for high performance liquid chromatography and determination of glucosamine in urine.

    Science.gov (United States)

    Xiong, Bo; Wang, Ling-Ling; Li, Qiong; Nie, Yu-Ting; Cheng, Shuang-Shuang; Zhang, Hui; Sun, Ren-Qiang; Wang, Yu-Jiao; Zhou, Hong-Bin

    2015-11-01

    A parallel microscope-based laser-induced fluorescence (LIF), ultraviolet-visible absorbance (UV) and time-of-flight mass spectrometry (TOF-MS) detection for high performance liquid chromatography (HPLC) was achieved and used to determine glucosamine in urines. First, a reliable and convenient LIF detection was developed based on an inverted microscope and corresponding modulations. Parallel HPLC-LIF/UV/TOF-MS detection was developed by the combination of preceding Microscope-based LIF detection and HPLC coupled with UV and TOF-MS. The proposed setup, due to its parallel scheme, was free of the influence from photo bleaching in LIF detection. Rhodamine B, glutamic acid and glucosamine have been determined to evaluate its performance. Moreover, the proposed strategy was used to determine the glucosamine in urines, and subsequent results suggested that glucosamine, which was widely used in the prevention of the bone arthritis, was metabolized to urines within 4h. Furthermore, its concentration in urines decreased to 5.4mM at 12h. Efficient glucosamine detection was achieved based on a sensitive quantification (LIF), a universal detection (UV) and structural characterizations (TOF-MS). This application indicated that the proposed strategy was sensitive, universal and versatile, and it was capable of improved analysis, especially for analytes with low concentrations in complex samples, compared with conventional HPLC-UV/TOF-MS. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. A radiation hard vacuum switch

    Science.gov (United States)

    Boettcher, G.E.

    1988-07-19

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

  4. Application of a DNA-based luminescence switch-on method for the detection of mercury(II) ions in water samples from Hong Kong

    Science.gov (United States)

    He, Hong-Zhang; Leung, Ka-Ho; Fu, Wai-Chung; Shiu-Hin Chan, Daniel; Leung, Chung-Hang; Ma, Dik-Lung

    2012-12-01

    Mercury is a highly toxic environmental contaminant that damages the endocrine and central nervous systems. In view of the contamination of Hong Kong territorial waters with anthropogenic pollutants such as trace heavy metals, we have investigated the application of our recently developed DNA-based luminescence methodology for the rapid and sensitive detection of mercury(II) ions in real water samples. The assay was applied to water samples from Shing Mun River, Nam Sang Wai and Lamma Island sea water, representing natural river, wetland and sea water media, respectively. The results showed that the system could function effectively in real water samples under conditions of low turbidity and low metal ion concentrations. However, high turbidity and high metal ion concentrations increased the background signal and reduced the performance of this assay.

  5. Design of NIR Chromenylium-Cyanine Fluorophore Library for "Switch-ON" and Ratiometric Detection of Bio-Active Species In Vivo.

    Science.gov (United States)

    Wei, Yanfen; Cheng, Dan; Ren, Tianbing; Li, Yinhui; Zeng, Zebing; Yuan, Lin

    2016-02-02

    The real-time monitoring of key biospecies in the living systems has received thrusting attention during the past decades. Specifically, fluorescent detection based on near-infrared (NIR) fluorescent probes is highly favorable for live cells, live tissues, and even animal imaging, owing to the substantial merits of the NIR window, such as minimal phototoxicity, deep penetration into tissues, and low autofluorescence background. Nevertheless, developing potent NIR fluorescent probes still poses serious challenges to the chemists because traditional NIR fluorophores are less tunable than visible-wavelength fluorophores. To address this issue, here we report a set of novel NIR hybrid fluorophores, namely, the hybrid chromenylium-cyanine fluorophore (CC-Fluor), in which both the fluorescence intensity and the emission wavelength can be easily adjusted by the conformational changes and substitution groups. Compared to known NIR fluorophores, the new CC-Fluors are substantially advantageous for NIR probe development: (1) CC-Fluors display tunable and moderate Stokes shifts and quantum yields; (2) the fluorophores are stable at physiological conditions after long-term incubation; (3) the absorption maxima of CC-Fluors coincide with the common laser spectral lines in mainstream in vivo imaging systems; (4) most importantly, CC-Fluors can be easily modified to prepare NIR probes targeting various biospecies. To fully demonstrate the practical utility of CC-Fluors, we report two innovative NIR probes, a ratiometric pH probe and a turn-on Hg(2+) probe, both are successfully employed in live animal imaging. Hence, the detailed studies allow us to confirm that CC-Fluors can work as an excellent platform for developing NIR probes for the detection of species in living systems.

  6. Determination of the anthraquinones aloe-emodin and aloin-A by liquid chromatography with mass spectrometric and diode array detection.

    Science.gov (United States)

    Elsohly, Mahmoud A; Gul, Waseem; Avula, Bharathi; Khan, Ikhlas A

    2007-01-01

    Methods using liquid chromatography/mass spectrometry (LC/MS) and LC with diode array detection (DAD) in the UV range (LC/UV) were developed for the determination of low levels of the anthraquinones aloe-emodin and aloin-A (barbaloin) in aloe-based products. The methods were used to analyze several commercial products (liquids, semisolids, and solids) for the 2 anthraquinones. The wavelengths used for quantification of aloin-A, aloe-emodin, and emodin (internal standard) by DAD were 357, 257, and 289 nm, respectively. The on-column sensitivities were 0.25 and 0.05 ng by LC/UV and 0.01 and 0.025 ng by LC/MS for aloin-A and aloe-emodin, respectively. The methods are simple and sensitive and provide reproducible results; therefore, they are suitable for the determination of these anthraquinones in various aloe-based products.

  7. Speciation of four selenium compounds using high performance liquid chromatography with on-line detection by inductively coupled plasma mass spectrometry or flame atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Pedersen, Gitte Alsing; Larsen, Erik Huusfeldt

    1997-01-01

    with an aqueous solution of 6 mmol L-1 of salicylate ion at pH 8.5 as the mobile phase which allowed the isocratic separation of the four selenium analytes within 8 minutes. The separated selenium species were detected on-line by flame atomic absorption spectrometry (FAAS) or inductively coupled plasma mass......An analytical method for the speciation of selenomethionine, selenocystine, selenite and selenate by high performance liquid chromatography (HPLC) with atomic spectrometric detection is presented. An organic polymeric strong anion exchange column was used as the stationary phase in combination...... spectrometry (ICP-MS). The signal-to-noise ratio of the FAAS detector was optimized using a hydrogen-argon entrained-air flame and a slotted-tube atom trap (STAT) in the flame. The limit of detection (3 sigma) achieved by the HPLC-FAAS system was 1 mg L-1 of selenium (100 mu L injections) for each of the four...

  8. Simultaneous determination of four trace estrogens in feces, leachate, tap and groundwater using solid-liquid extraction/auto solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Liu, Na; Shi, Yue-e; Li, Mengyan; Zhang, Ting-di; Gao, Song

    2015-10-01

    A simple and selective high-performance liquid chromatography method coupled with fluorescence detection was developed for the simultaneous measurement of trace levels of four estrogens (estrone, estradiol, estriol and 17α-ethynyl estradiol) in environmental matrices. For feces samples, solid-liquid extraction was applied with a 1:1 v/v mixture of acetonitrile and ethyl acetate as the extraction solvent. For liquid samples (e.g., leachate and groundwater), hydrophobic/lipophilic balanced automated solid-phase extraction disks were selected due to their high recoveries compared to conventional C18 disks. Chromatographic separations were performed on a reversed-phase C18 column gradient-eluted with a 45:55 v/v mixture of acetonitrile and water. The detection limits were down to 1.1 × 10(-2) (estrone), 4.11 × 10(-4) (estradiol), 5.2 × 10(-3) (estriol) and 7.18 × 10(-3) μg/L (17α-ethynyl estradiol) at excitation/emission wavelengths of 288/310 nm, with recoveries in the range of 96.9 ± 3.2-105.4 ± 3.2% (n = 3). The method was successfully applied to determine estrogens in feces and water samples collected at livestock farms and a major river in Northeast China. We observed relatively high abundance and widespread distribution of all four estrogens in our sample collections, implying the urgency for a comprehensive and intricate investigation of estrogenic fate and contamination in our researched area. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Hollow fiber supported liquid-phase microextraction using ionic liquid as extractant for preconcentration of benzene, toluene, ethylbenzene and xylenes from water sample with gas chromatography-hydrogen flame ionization detection.

    Science.gov (United States)

    Ma, Xiaoguo; Huang, Minghua; Li, Zhihua; Wu, Jianmei

    2011-10-30

    A novel method has been developed for the analysis of benzene, toluene, ethyl-benzene, and o-, m- and p-xylenes (BTEXs) in water using hollow fiber supported liquid-phase microextraction (HF-LPME) followed by gas chromatography-hydrogen flame ionization detection. Ionic liquid 1-butyl-3-methy-limidazolium hexafluorophosphate ([BMIM][PF(6)]) was acted as the extractant for extraction and preconcentration of BTEXs from aqueous samples, and a porous-walled polypropylene hollow fiber was utilized to stabilize and protect [BMIM][PF(6)] during the extraction process. Various parameters that affect extraction efficiency were investigated in detail, and the optimized experimental conditions were as follows: 8 μL of [BMIM][PF(6)] as extraction solvent for the target analytes in 20 mL of sample solution, 30 min of extraction time, a stirring rate of 1400 rpm and 15% NaCl (w/v) in aqueous sample at 25°C (ambient temperature). The recovery was found to be 90.0-111.5% with RSD (n=5) of 1.3-5.4%, and the detection limits (S/N=3) were in the range of 2.7-4.0 μg/L. The proposed method was simple, cheap, rapid, sensitive and environmentally benign, and could act as an alternative to techniques for BTEXs analysis with expensive instrumentations. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Persistent-current switch for pancake coils of rare earth-barium-copper-oxide high-temperature superconductor: Design and test results of a double-pancake coil operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K)

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Timing; Michael, Philip C.; Bascuñán, Juan; Iwasa, Yukikazu, E-mail: iwasa@jokaku.mit.edu [Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139 (United States); Voccio, John [Wentworth Institute of Technology, 550 Huntington Ave, Boston, Massachusetts 02115 (United States); Hahn, Seungyong [National High Magnetic Field Laboratory, Florida State University, Tallahassee, 2031 Paul Dirac Drive, Florida 32310 (United States)

    2016-08-22

    We present design and test results of a superconducting persistent current switch (PCS) for pancake coils of rare-earth-barium-copper-oxide, REBCO, high-temperature superconductor (HTS). Here, a REBCO double-pancake (DP) coil, 152-mm ID, 168-mm OD, 12-mm high, was wound with a no-insulation technique. We converted a ∼10-cm long section in the outermost layer of each pancake to a PCS. The DP coil was operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K). Over the operating temperature ranges of this experiment, the normal-state PCS enabled the DP coil to be energized; thereupon, the PCS resumed the superconducting state and the DP coil field decayed with a time constant of 100 h, which would have been nearly infinite, i.e., persistent-mode operation, were the joint across the coil terminals superconducting.

  11. Detection of prohibited substances in equine hair by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry - application to doping control samples.

    Science.gov (United States)

    Gray, B; Viljanto, M; Menzies, E; Vanhaecke, L

    2018-02-12

    The detection of drugs in human hair samples has been performed by laboratories around the world for many years and the matrix is popular in disciplines such as workplace drug testing. To date, however, hair has not become a routinely utilised matrix in sports drug detection. The analysis of hair samples offers a number of potential advantages to doping control laboratories, not least of which are the greatly extended detection window and the ease of sample collection and storage. This paper describes the development, validation and utilisation of a sensitive ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-MS/MS) method for the detection of 50 compounds. This provides significantly improved coverage for those analytes which would be of particular interest if detected in hair, such as anabolic steroid esters and selective androgen receptor modulators (SARMs). Qualitative validation of the method resulted in estimated limits of detection as low as 0.1 pg/mg for the majority of compounds, with all being detected at 2 pg/mg or below. The suitability of the method for the detection of prohibited substances in incurred material was demonstrated by the successful detection of a number of compounds, such as stanozolol, boldenone undecylenate, clenbuterol and GW-501516, in genuine equine hair samples. Estimated concentrations of the detected substances ranged from 0.27 to 8.6 pg/mg. The method has been shown to be fit-for-purpose for routine screening of equine hair samples by the analysis of over 400 genuine hair samples. This article is protected by copyright. All rights reserved.

  12. Determination of methyldibromoglutaronitrile in cosmetic products by high-performance liquid chromatography with electrochemical detection. Method validation

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Zachariae, Claus; Johansen, Jeanne D

    2004-01-01

    An increased frequency of contact allergy to methyldibromoglutaronitrile (MDBGN), a commonly used preservative in cosmetics and other consumer products, has been reported in recent years. A high-performance liquid chromatography (HPLC) method for the determination of MDBGN in cosmetic products ha...

  13. Maximizing the peak production rate in off-line comprehensive two-dimensional liquid chromatography with mass spectrometry detection

    NARCIS (Netherlands)

    Eeltink, S.; Dolman, S.; Ursem, M.; Swart, R.; McLeod, F.; Schoenmakers, P.J.

    2009-01-01

    This article describes an optimization strategy to obtain the best possible performance in the shortest analysis time—called the peak production rate—for comprehensive off-line two-dimensional liquid chromatography. The demands on column technology (particle size and column length) and LC conditions

  14. Preventive doping control analysis: Liquid and gas chromatography time-to-flight mass spectrometry for detection of designer steriods

    NARCIS (Netherlands)

    Georgakopoulos, C.G.; Vonaparti, A.; Stamou, M.; Kiousi, P.; Lyris, E.; Angelis, Y.S.; Tsoupras, G.; Wuest, B.; Nielen, M.W.F.; Panderi, I.; Koupparis, M.

    2007-01-01

    A new combined doping control screening method for the analysis of anabolic steroids in human urine using liquid chromatography/electrospray ionization orthogonal acceleration time-of-flight mass spectrometry (LCoaTOFMS) and gas chromatography/electron ionization orthogonal acceleration

  15. Pretreatment of various feedstocks for lactic acid production: detection of sugars, organic acids and furanics in liquid fractions

    NARCIS (Netherlands)

    Harmsen, P.F.H.; Lips, S.J.J.; Bakker, R.R.C.

    2012-01-01

    Barley straw, sugarcane bagasse and empty fruit bunches were pretreated under acid- and alkaline conditions. Solid phase was separated from the liquid phase and the concentration of dissolved monomeric sugars, organic acids and furanics was determined. Acid hydrolysis yielded monomeric xylose

  16. The use of liquid chromatography tandem mass spectrometry to detect proteins in saliva from horses with and without systemic inflammation

    DEFF Research Database (Denmark)

    Jacobsen, Stine; Adler, Ditte Marie Top; Bundgaard, Louise

    2014-01-01

    , and alpha1-acid glycoprotein. The study is the first to describe detection of inflammatory proteins in horse saliva. The proteins detected were similar to those described in saliva from cattle, small ruminants and pigs. Detection of APPs in horses with systemic inflammation suggests that saliva may be used...... for non-invasive disease monitoring in horses as in humans, pigs and dogs...

  17. Liquid chromatography with diode array detection combined with spectral deconvolution for the analysis of some diterpene esters in Arabica coffee brew.

    Science.gov (United States)

    Erny, Guillaume L; Moeenfard, Marzieh; Alves, Arminda

    2015-02-01

    In this manuscript, the separation of kahweol and cafestol esters from Arabica coffee brews was investigated using liquid chromatography with a diode array detector. When detected in conjunction, cafestol, and kahweol esters were eluted together, but, after optimization, the kahweol esters could be selectively detected by setting the wavelength at 290 nm to allow their quantification. Such an approach was not possible for the cafestol esters, and spectral deconvolution was used to obtain deconvoluted chromatograms. In each of those chromatograms, the four esters were baseline separated allowing for the quantification of the eight targeted compounds. Because kahweol esters could be quantified either using the chromatogram obtained by setting the wavelength at 290 nm or using the deconvoluted chromatogram, those compounds were used to compare the analytical performances. Slightly better limits of detection were obtained using the deconvoluted chromatogram. Identical concentrations were found in a real sample with both approaches. The peak areas in the deconvoluted chromatograms were repeatable (intraday repeatability of 0.8%, interday repeatability of 1.0%). This work demonstrates the accuracy of spectral deconvolution when using liquid chromatography to mathematically separate coeluting compounds using the full spectra recorded by a diode array detector. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Energy reversible switching from amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-08-01

    We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

  19. Microfabricated triggered vacuum switch

    Science.gov (United States)

    Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM

    2010-05-11

    A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

  20. Switching power supply

    Science.gov (United States)

    Mihalka, A.M.

    1984-06-05

    The invention is a repratable capacitor charging, switching power supply. A ferrite transformer steps up a dc input. The transformer primary is in a full bridge configuration utilizing power MOSFETs as the bridge switches. The transformer secondary is fed into a high voltage, full wave rectifier whose output is connected directly to the energy storage capacitor. The transformer is designed to provide adequate leakage inductance to limit capacitor current. The MOSFETs are switched to the variable frequency from 20 to 50 kHz to charge a capacitor from 0.6 kV. The peak current in a transformer primary and secondary is controlled by increasing the pulse width as the capacitor charges. A digital ripple counter counts pulses and after a preselected desired number is reached an up-counter is clocked.