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Sample records for generation electrothermal vaporization

  1. A highly sensitive method for the determination of mercury using vapor generation gold wire microextraction and electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Hashemi, Payman; Rahimi, Akram

    2007-04-01

    The study introduces a new simple and highly sensitive method for headspace solid phase microextraction (HS-SPME) coupled with electrothermal atomic absorption spectrometric determination of mercury. In the proposed method, a gold wire, mounted in the headspace of a sample solution in a sealed bottle, is used for collection of mercury vapor generated by addition of sodium tetrahydroborate. The gold wire is then simply inserted in the sample introduction hole of a graphite furnace of an electrothermal atomic absorption spectrometry instrument. By applying an atomization temperature of 600 °C, mercury is rapidly desorbed from the wire and determined with high sensitivity. Factorial design and response surface analysis methods were used for optimization of the effect of five different variables in order to maximize the mercury signal. By using a 0.75 mm diameter gold wire, a sample volume of about 8 ml and an extraction time of 11 min, the sensitivity of mercury determination was enhanced up to 10 4 times in comparison to its ordinary ETAAS determination with direct injection of 10 μl sample solutions. A detection limit of 0.006 ng ml - 1 and a precision better than 4.6% (relative standard deviation) were obtained. The method was successfully applied to the determination of mercury in industrial wastewaters and tuna fish samples.

  2. Optimization of a single-drop microextraction method for multielemental determination by electrothermal vaporization inductively coupled plasma mass spectrometry following in situ vapor generation

    NASA Astrophysics Data System (ADS)

    Gil, Sandra; de Loos-Vollebregt, Margaretha T. C.; Bendicho, Carlos

    2009-03-01

    A headspace single-drop microextraction (HS-SDME) method has been developed in combination with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the simultaneous determination of As, Sb, Bi, Pb, Sn and Hg in aqueous solutions. Vapor generation is carried out in a 40 mL volume closed-vial containing a solution with the target analytes in hydrochloric acid and potassium ferricyanide medium. Hydrides (As, Sb, Bi, Pb, Sn) and Hg vapor are trapped onto an aqueous single drop (3 µL volume) containing Pd(II), followed by the subsequent injection in the ETV. Experimental variables such as medium composition, sodium tetrahydroborate (III) volume and concentration, stirring rate, extraction time, sample volume, ascorbic acid concentration and palladium amount in the drop were fully optimized. The limits of detection (LOD) (3 σ criterion) of the proposed method for As, Sb, Bi, Pb, Sn and Hg were 0.2, 0.04, 0.01, 0.07, 0.09 and 0.8 µg/L, respectively. Enrichment factors of 9, 85, 138, 130, 37 and 72 for As, Sb, Bi, Pb, Sn and Hg, respectively, were achieved in 210 s. The relative standard deviations ( N = 5) ranged from 4 to 8%. The proposed HS-SDME-ETV-ICP-MS method has been applied for the determination of As, Sb, Bi, Pb, Sn and Hg in NWRI TM-28.3 certified reference material.

  3. Organic, inorganic and total mercury determination in fish by chemical vapor generation with collection on a gold gauze and electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Duarte, Fábio Andrei; Bizzi, Cezar Augusto; Antes, Fabiane Goldschmidt; Dressler, Valderi Luiz; Flores, Érico Marlon de Moraes

    2009-06-01

    A method for organic, inorganic and total mercury determination in fish tissue has been developed using chemical vapor generation and collection of mercury vapor on a gold gauze inside a graphite tube and further atomization by electrothermal atomic absorption spectrometry. After drying and cryogenic grinding, potassium bromide and hydrochloric acid solution (1 mol L - 1 KBr in 6 mol L - 1 HCl) was added to the samples. After centrifugation, total mercury was determined in the supernatant. Organomercury compounds were selectively extracted from KBr solution using chloroform and the resultant solution was back extracted with 1% m/v L-cysteine. This solution was used for organic Hg determination. Inorganic Hg remaining in KBr solution was directly determined by chemical vapor generation electrothermal atomic absorption spectrometry. Mercury vapor generation from extracts was performed using 1 mol L - 1 HCl and 2.5% m/v NaBH 4 solutions and a batch chemical vapor generation system. Mercury vapor was collected on the gold gauze heated resistively at 80 °C and the atomization temperature was set at 650 °C. The selectivity of extraction was evaluated using liquid chromatography coupled to chemical vapor generation and determination by inductively coupled plasma mass spectrometry. The proposed method was applied for mercury analysis in shark, croaker and tuna fish tissues. Certified reference materials were used to check accuracy and the agreement was better than 95%. The characteristic mass was 60 pg and method limits of detection were 5, 1 and 1 ng g - 1 for organic, inorganic and total mercury, respectively. With the proposed method it was possible to analyze up to 2, 2 and 6 samples per hour for organic, inorganic and total Hg determination, respectively.

  4. Electrothermal vaporization, part 1: gas phase chemistry

    NASA Astrophysics Data System (ADS)

    Majidi, Vahid; Xu, Ning; Smith, Robert G.

    2000-01-01

    This manuscript is the first of a two-part publication on evaluation of vaporization and atomization processes in electrothermal vaporizers (ETV). Part 1 is specifically focused on gas phase (and heterogeneous) chemistry in ETVs. Molecular absorption spectroscopy and thermogravimetric analysis (in conjunction with gas-phase mass spectrometry) are used to investigate the vaporization of Mg, Ca, Sr, Ba, Co and Ni (chloride and nitrate salts). Graphite, Pt, and Ta were used as substrate material for vaporizers to elucidate some observations of gas-phase chemistry. The experiments in Part I and II of this series are intentionally performed using wall vaporization to closely mimic the conditions used when ETV is employed as a sample introduction device.

  5. Determination of plutonium in urine: evaluation of electrothermal vaporization inductively coupled plasma mass spectroscopy

    SciTech Connect

    Pietrzak, R.; Kaplan, E.

    1996-11-01

    Mass spectroscopy has the distinct advantage of detecting atoms rather than radioactive decay products for nuclides of low specific activity. Electrothermal vaporization (ETV) is an efficient means of introducing small volumes of prepared samples into an inductively coupled mass spectrometer to achieve the lowest absolute detection limits. The operational characteristics and capabilities of electrothermal vaporization inductively coupled mass spectrometer mass spectroscopy were evaluated. We describe its application as a detection method for determining Pu in urine, in conjunction with a preliminary separation technique to avoid matrix suppression of the signal.

  6. An electrothermal vaporization unit with axially focusing convection upstream and influence of modifiers. Part I: Experimental

    NASA Astrophysics Data System (ADS)

    Trenin, A.; Gafurov, M.; Gilmutdinov, A. Kh.; Hermann, G.

    2007-03-01

    A novel, further improved construction of an electrothermal vaporization (ETV) unit is described, and new measurements are presented. Its main feature is an upstream within a vertical tube creating an axially focusing convection zone, where the condensation occurs in a laminar flow predominantly apart from the colder walls. The upstream is shielded against incandescent emission of the graphite furnace (GF) and surrounded with different cooling gas flows, that have additional focusing effect. The transported ETV generated aerosol is electrostatically precipitated onto a secondary platform that is subsequently analyzed for the transported analytes. Transport efficiencies (TEs) for Cu, Fe, Mn, Ni, and Pb are studied using a continuum source coherent forward scattering multi-element spectrometer coupled to the ETV. Increasing TE is observed with the ageing of the GF. The effect is presumably ascribed to the growing content of carbon particulates released during the vaporization. A positive impact of K and Pd modifiers in microgram amounts foremost on the TEs of more volatile species is observed and discussed.

  7. Calibrated vapor generator source

    DOEpatents

    Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

    1995-09-26

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

  8. Calibrated vapor generator source

    DOEpatents

    Davies, John P.; Larson, Ronald A.; Goodrich, Lorenzo D.; Hall, Harold J.; Stoddard, Billy D.; Davis, Sean G.; Kaser, Timothy G.; Conrad, Frank J.

    1995-01-01

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet.

  9. Electrothermal gas generator: Development and qualification of the control electronics

    NASA Astrophysics Data System (ADS)

    Matthaeus, G.; Schmitz, H. D.

    1986-07-01

    The development and qualification of an electronic control circuitry for an electrothermal or catalytic hydrazine gas generator system is described. The circuitry, named manual override, controls the gas pressure in a tank using a pressure transducer and the gas generator to keep the pressure constant within narrow tolerances. The present pressure can be varied by ground command, enabling a variable thrust of the gas fed cold gas thrusters. The automatic loop can be switched off and the tank pressure be controlled by ground command. Two manual overrides SN01 and SN02 were qualified.

  10. Determination of mercury in fish samples by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Liaw, Ming-Jyh; Jiang, Shiuh-Jen; Li, Yi-Ching

    1997-06-01

    Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determination of mercury in several fish samples. The effects of instrument operating conditions and slurry preparation on the ion signals are reported. Palladium was used as modifier to delay the vaporization of mercury in this study. As the vaporization behavior of mercury in fish slurry and aqueous solution is quite different, the standard addition method was used for the determination of mercury in reference materials. The detection limit of mercury estimated from the standard addition curve was in the range 0.002-0.004 μg g -1 for different samples. This method has been applied to the determination of mercury in dogfish muscle reference material (DORM-1 and DORM-2) and dogfish liver reference material (DOLT-1). Accuracy was better than 4% and precision was better than 7% with the USS-ETV-ICP-MS method.

  11. Linearization of calibration curves by aerosol carrier effect of CCl 4 vapor in electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kántor, Tibor; de Loos-Vollebregt, Margaretha T. C.

    2005-03-01

    Carbon tetrachloride vapor as gaseous phase modifier in a graphite furnace electrothermal vaporizer (GFETV) converts heavy volatile analyte forms to volatile and medium volatile chlorides and produces aerosol carrier effect, the latter being a less generally recognized benefit. However, the possible increase of polyatomic interferences in inductively coupled plasma mass spectrometry (GFETV-ICP-MS) by chlorine and carbon containing species due to CCl 4 vapor introduction has been discouraging with the use of low resolution, quadrupole type MS equipment. Being aware of this possible handicap, it was aimed at to investigate the feasibility of the use of this halogenating agent in ICP-MS with regard of possible hazards to the instrument, and also to explore the advantages under these specific conditions. With sample gas flow (inner gas flow) rate not higher than 900 ml min -1 Ar in the torch and 3 ml min -1 CCl 4 vapor flow rate in the furnace, the long-term stability of the instrument was ensured and the following benefits by the halocarbon were observed. The non-linearity error (defined in the text) of the calibration curves (signal versus mass functions) with matrix-free solution standards was 30-70% without, and 1-5% with CCl 4 vapor introduction, respectively, at 1 ng mass of Cu, Fe, Mn and Pb analytes. The sensitivity for these elements increased by 2-4-fold with chlorination, while the relative standard deviation (RSD) was essentially the same (2-5%) for the two cases in comparison. A vaporization temperature of 2650 °C was required for Cr in Ar atmosphere, while 2200 °C was sufficient in Ar + CCl 4 atmosphere to attain complete vaporization. Improvements in linear response and sensitivity were the highest for this least volatile element. The pyrolytic graphite layer inside the graphite tube was protected by the halocarbon, and tube life time was further increased by using traces of hydrocarbon vapor in the external sheath gas of the graphite furnace. Details

  12. Stratified vapor generator

    DOEpatents

    Bharathan, Desikan; Hassani, Vahab

    2008-05-20

    A stratified vapor generator (110) comprises a first heating section (H.sub.1) and a second heating section (H.sub.2). The first and second heating sections (H.sub.1, H.sub.2) are arranged so that the inlet of the second heating section (H.sub.2) is operatively associated with the outlet of the first heating section (H.sub.1). A moisture separator (126) having a vapor outlet (164) and a liquid outlet (144) is operatively associated with the outlet (124) of the second heating section (H.sub.2). A cooling section (C.sub.1) is operatively associated with the liquid outlet (144) of the moisture separator (126) and includes an outlet that is operatively associated with the inlet of the second heating section (H.sub.2).

  13. Slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for steelmaking flue dust analysis

    NASA Astrophysics Data System (ADS)

    Coedo, A. G.; Dorado, T.; Padilla, I.; Maibusch, R.; Kuss, H.-M.

    2000-02-01

    A commercial atomic absorption graphite furnace (AAGF), with a self-made adapter and valve system, was used as a slurry sampling cell for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). The system was applied to the determination of As, Sn, Sb, Se, Te, Bi, Cd, V, Ti and Mo in steelmaking flue dusts. Experimental conditions with respect to ETV and ICP-MS operating parameters were optimized. Compared to aqueous solutions, slurry samples were found to present better analyte transport. Microgram amounts of Rh were used to reduce the difference in analyte response in sensitivity for aqueous solutions of the tested analytes. No such increasing effect was observed for slurry samples and aqueous standards. An added quantity of Rh acting as modifier/carrier resulted in an increase for the same analytes in matrix-slurry solutions, even the addition of an extra Rh quantity has resulted in a decrease in the signals. The effect of Triton X-100 (used as a dispersant agent) on analyte intensity and precision was also studied. External calibration from aqueous standards spiked with 100 μg ml -1 Rh was performed to quantified 0.010 g/100 ml slurry samples. Results are presented for a certified reference electrical arc furnace flue dust (EAF): CRM-876-1 (Bureau of Analysis Samples Ltd., Cleveland, UK), a reference sample of coke ashes X-3705 (from AG der Dillinger Hüttenwerke, Germany), and a representative sample of EAF flue dust from a Spanish steelmaking company (CENIM-1). For the two reference materials an acceptable agreement with certificate values was achieved, and the results for the CENIM sample matched with those obtained from conventional nebulization solution.

  14. Electrothermal Vaporization Sample Introduction for Spaceflight Water Quality Monitoring via Gas Chromatography-Differential Mobility Spectrometry.

    PubMed

    Wallace, William T; Gazda, Daniel B; Limero, Thomas F; Minton, John M; Macatangay, Ariel V; Dwivedi, Prabha; Fernández, Facundo M

    2015-06-16

    In the history of manned spaceflight, environmental monitoring has relied heavily on archival sampling. However, with the construction of the International Space Station (ISS) and the subsequent extension in mission duration up to one year, an enhanced, real-time method for environmental monitoring is necessary. The station air is currently monitored for trace volatile organic compounds (VOCs) using gas chromatography-differential mobility spectrometry (GC-DMS) via the Air Quality Monitor (AQM), while water is analyzed to measure total organic carbon and biocide concentrations using the Total Organic Carbon Analyzer (TOCA) and the Colorimetric Water Quality Monitoring Kit (CWQMK), respectively. As mission scenarios extend beyond low Earth orbit, a convergence in analytical instrumentation to analyze both air and water samples is highly desirable. Since the AQM currently provides quantitative, compound-specific information for air samples and many of the targets in air are also common to water, this platform is a logical starting point for developing a multimatrix monitor. Here, we report on the interfacing of an electrothermal vaporization (ETV) sample introduction unit with a ground-based AQM for monitoring target analytes in water. The results show that each of the compounds tested from water have similar GC-DMS parameters as the compounds tested in air. Moreover, the ETV enabled AQM detection of dimethlsilanediol (DMSD), a compound whose analysis had proven challenging using other sample introduction methods. Analysis of authentic ISS water samples using the ETV-AQM showed that DMSD could be successfully quantified, while the concentrations obtained for the other compounds also agreed well with laboratory results. PMID:25971650

  15. Development and characterization of induction heating electrothermal vaporization (IH-ETV) sample introduction for inductively coupled plasma spectrometry

    NASA Astrophysics Data System (ADS)

    Rybak, Michael E.; Salin, Eric D.

    2001-03-01

    A general study of performance attributes was conducted for a prototypical electrothermal vaporization (ETV) sample introduction system, in which induction heating (IH) was used to facilitate the drying, pyrolysis, and vaporization of samples from long, undercut graphite cup probes in a radio-frequency (RF) induction field. In the first part of this study, experiments were carried out to determine the heating characteristics and temperature control aspects of an IH-ETV arrangement. Using a remote-sensing infrared thermocouple, it was determined that a 3/8-inch (9.53-mm) outer diameter graphite cup sample probe could be heated to a maximum temperature of 1860°C in the induction field of the IH-ETV under full forward power (1.5 kW). The IH-ETV device was found to have a rapid heating response (1/ e time-constant of 2.0±0.2 s) that was independent of the initial/final temperatures chosen. Linear temperature control was possible by regulating either the DC voltage applied to the plate or the current flowing to the grid of the RF generator oscillator tube. The second part of this work consisted of studies to establish benchmarks, such as limits of detection (LOD) with inductively coupled plasma optical emission spectrometry (ICP-OES) and transport efficiency for analyte vaporization under several x-Ar mixed gas atmospheres [where x=15% N 2, 10% O 2, HCl (sparged), or 15% SF 6 (v/v)]. In general, reproducible transient signals with evolution times of 5-15 s were seen for the vaporization of most elements studied, with peak area intensity and reproducibility generally being the best with SF 6-Ar. A 10-fold increase in transport efficiency was seen for refractory carbide-forming analytes (Cr, V) when vaporization was conducted in a halogenous ( x=HCl, SF 6) versus non-halogenous ( x=N 2, O 2) environment, with a two-fold improvement being observed for most other non-refractory elements (Cd, Cu, Fe, Mn, Ni, Pb, Zn). The transport of arsenic proved to be a special case

  16. Determination of some refractory elements and Pb by fluorination assisted electrothermal vaporization inductively coupled plasma mass spectrometry with platform and wall vaporization

    NASA Astrophysics Data System (ADS)

    Zhang, Yuefei; Hu, Bin

    2011-02-01

    Platform and wall vaporization for electrothermal vaporization (ETV)-inductively coupled plasma mass spectrometry (ICP-MS) determination of some refractory elements (Ti, V, Cr, Mo, La and Zr) and Pb were comparatively studied with the use of poly (tetrafluoroethylene) (PTFE) as fluorinating reagent. The factors affecting the vaporization behaviors of the target analytes in the platform and tube wall vaporization including vaporization temperature and time, pyrolytic temperature and time were studied in detail, and the flow rates of carrier gas/auxiliary carrier gas, were carefully optimized. Under the optimal conditions, the signal profiles, signal intensity, interferences of coexisting ions and analytical reproducibility for wall and platform vaporization ETV-ICP-MS were compared. It was found that both wall and platform vaporization could give very similar detection limits, but the platform vaporization provided higher signal intensity and better precision for some refractory elements and Pb than the wall vaporization. Especially for La, the signal intensity obtained by platform vaporization was 3 times higher than that obtained by wall vaporization. For platform vaporization ETV-ICP-MS, the limits of detection (LODs) of 0.001 μg L -1 (La) ~ 0.09 μg L - 1 (Ti) with the relative standard deviations (RSDs) of 1.5% (Pb) ~ 15.5% (Zr) were obtained. While for wall vaporization ETV-ICP-MS, LODs of 0.005 μg L - 1 (La) ~ 0.4 μg L - 1 (Pb) with RSDs of 3.2% (Mo) ~ 12.8% (Zr) were obtained. Both platform and tube wall vaporization techniques have been used for slurry sampling fluorination assisted ETV-ICP-MS direct determination of Ti, V, Cr, Mo, La, Zr and Pb in certified reference materials of NIES No. 8 vehicle exhaust particulates and GBW07401 soil, and the analytical results obtained are in good agreement with the certified values.

  17. Electro-thermal vaporization direct analysis in real time-mass spectrometry for water contaminant analysis during space missions.

    PubMed

    Dwivedi, Prabha; Gazda, Daniel B; Keelor, Joel D; Limero, Thomas F; Wallace, William T; Macatangay, Ariel V; Fernández, Facundo M

    2013-10-15

    The development of a direct analysis in real time-mass spectrometry (DART-MS) method and first prototype vaporizer for the detection of low molecular weight (∼30-100 Da) contaminants representative of those detected in water samples from the International Space Station is reported. A temperature-programmable, electro-thermal vaporizer (ETV) was designed, constructed, and evaluated as a sampling interface for DART-MS. The ETV facilitates analysis of water samples with minimum user intervention while maximizing analytical sensitivity and sample throughput. The integrated DART-ETV-MS methodology was evaluated in both positive and negative ion modes to (1) determine experimental conditions suitable for coupling DART with ETV as a sample inlet and ionization platform for time-of-flight MS, (2) to identify analyte response ions, (3) to determine the detection limit and dynamic range for target analyte measurement, and (4) to determine the reproducibility of measurements made with the method when using manual sample introduction into the vaporizer. Nitrogen was used as the DART working gas, and the target analytes chosen for the study were ethyl acetate, acetone, acetaldehyde, ethanol, ethylene glycol, dimethylsilanediol, formaldehyde, isopropanol, methanol, methylethyl ketone, methylsulfone, propylene glycol, and trimethylsilanol. PMID:24050110

  18. Direct determination of bromine in plastics by electrothermal vaporization/inductively coupled plasma mass spectrometry using a tungsten boat furnace vaporizer and an exchangeable sample cuvette system.

    PubMed

    Okamoto, Yasuaki; Komori, Hiromi; Kataoka, Hiroko; Tsukahara, Satoshi; Fujiwara, Terufumi

    2010-05-15

    A tungsten boat furnace vaporization inductively coupled plasma mass spectrometry (TBF/ICP-MS) method has been applied to the direct determination of bromine in plastic samples. In the pretreatment, the plastic sample is spread over a small sample cuvette made of tungsten by treating it with a strongly basic organic solution, e.g., octanol or diisobutyl ketone in the presence of potassium hydroxide. The cuvette is placed on a tungsten boat furnace, with which the electrothermal vaporizer is equipped. At the vaporization step, a widely spread thin layer of the sample facilitates its efficient evaporation and introduction into an ICP mass spectrometer. The most remarkable feature is that all the bromine species in plastic samples are decomposed to form a thermally stable inorganic salt during the pretreatment procedure. Therefore, the bromine content in plastic samples can be measured by a calibration curve method constructed with an aqueous standard solution of potassium bromate(V). The detection limit (3sigma) was estimated to be 0.77 pg of bromine, which corresponds to a concentration of 0.31 ng g(-1) of bromine in plastic samples when a sample amount taken of 2.5 mg is studied. The relative standard deviation was calculated to be 2.2%. Analytical results of some plastic samples, which contained both inorganic bromide salts and also organic bromine species, are given. PMID:20391597

  19. Vapor generation methods for explosives detection research

    SciTech Connect

    Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

    2012-12-01

    The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of the explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed flow vapor generators. Vapor sources for continuous flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by s programmed thermal desorption. This article reviews vapor generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatographic system with two ovens that is configurable with up to four heating ropes is proposed that could serve as a single integrated platform for explosives vapor generation and device testing. Issues related to standards, calibration, and safety are also discussed.

  20. Next Generation Electrocaloric and Pyroelectric Materials for Solid State Electrothermal Interconversion

    NASA Astrophysics Data System (ADS)

    Alpay, S. Pamir; Mantese, Joseph V.; Trolier-McKinstry, Susan; Zhang, Qiming; Whatmore, Roger W.

    2015-03-01

    Thin film electrocaloric (EC) and pyroelectric (PE) electrothermal interconversion energy sources have recently emerged as viable means for primary and auxiliary solid state cooling and power generation. This emergence is a result of two significant developments: (1) advancements in the formation of high quality polymeric and ceramic thin films with figures of merit that project system level performance as a large percentage of Carnot efficiency, and (2) the ability of these newer materials to support larger electric fields which permit operation at higher voltage; thus making the power electronic architectures more favorable for thermal to electric interconversion. Current research targets to adequately address commercial device needs, include reduction of parasitic losses, increases in mechanical robustness, and the ability to form nearly free-standing element in the range of 1 - 10 microns in thickness. This article will describe the current state-of-the-art materials, thermodynamic cycles and device losses; pointing to potential lines of research that would lead to substantially better figures of merit for electrothermal interconversion.

  1. Permanent iridium modifier deposited on tungsten and zirconium-treated platforms in electrothermal atomic absorption spectrometry: vaporization of bismuth, silver and tellurium

    NASA Astrophysics Data System (ADS)

    Slaveykova, Vera I.; Lampugnani, Leonardo; Tsalev, Dimiter L.; Sabbatini, L.; De Giglio, Elvira

    1999-04-01

    The stabilizing role of permanent iridium modifier deposited on tungsten-treated (WTP) and zirconium-treated (ZrTP) platforms of transversely heated graphite atomizer (THGA) was studied in detail by electrothermal atomic absorption spectrometry (ETAAS) and different surface techniques in model experiments for Ag, Bi and Te. The comparison of the stabilizing efficiency of permanent Ir modifier on WTP and ZrTP and each of the single components, reveals the better effect of Ir on WTP and Ir itself. The extent of analyte losses during pre-atomization and the strength of analyte association with the modifier were estimated by the plotting of `differential vaporization curves'. The existence of double peaks of Ag, Bi and Te in WTP and Ir on WTP was confirmed and possible reasons for their formation were discussed. The absorbance profiles presented as differential curves reveal an existence of at least two different types of precursors determining processes of atom generation. The observed differences in the behavior of Ir permanent modifier on WTP and ZrTP, respectively, were explained by the different extent of iridium-tungsten and iridium-zirconium interaction and surface distribution. XRF, ESCA and SEM studies reveal non-uniform distribution of the modifier on the graphite substrate and the presence of oxide containing species on the surface.

  2. Influence of sample matrix components on the selection of calibration strategies in electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Fonseca, R. W.; Miller-Ihli, N. J.

    1996-11-01

    Quantification of both digested and slurry samples were studied using ultrasonic slurry electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS). The results of external calibration using aqueous standards, method of additions, and In as an internal standard were compared. The elements studied include: Mn, Ni and Cu and the materials analyzed include: NIST SRM 1548 total diet and SRM 1549 milk powder. Palladium was used as a physical carrier and oxygen ashing was used to remove the organic part of the slurry matrix. Different degrees of matrix suppression effects were observed when different skimmer cones were employed. Aging of the skimmer cone and consequent loss of its original circular symmetry and decrease in orifice size resulted in differences in sampling of the ion beam and changes in the degree of matrix effects were observed as the skimmer cone was rotated. The presence of matrix suppression effects is evidenced by strong suppressions in the Ar 2, C and analyte signals. When matrix suppression effects were present, the method of external calibration provided low recoveries (average accuracy 73 ± 12%), therefore it was necessary to use the method of additions to compensate for these problems, providing an average accuracy of 108 ± 13%. When matrix effects were absent, the external calibration method resulted in an average accuracy of 101 ± 16%.

  3. Control of flow through a vapor generator

    DOEpatents

    Radcliff, Thomas D.

    2005-11-08

    In a Rankine cycle system wherein a vapor generator receives heat from exhaust gases, provision is made to avoid overheating of the refrigerant during ORC system shut down while at the same time preventing condensation of those gases within the vapor generator when its temperature drops below a threshold temperature by diverting the flow of hot gases to ambient and to thereby draw ambient air through the vapor generator in the process. In one embodiment, a bistable ejector is adjustable between one position, in which the hot gases flow through the vapor generator, to another position wherein the gases are diverted away from the vapor generator. Another embodiment provides for a fixed valve ejector with a bias towards discharging to ambient, but with a fan on the downstream side of said vapor generator for overcoming this bias.

  4. Sample transport efficiency with electrothermal vaporization and electrostatic deposition technique in multielement solid sample analysis of plant and cereal materials

    NASA Astrophysics Data System (ADS)

    Bernhardt, Jens; Buchkamp, Thomas; Hermann, Gerd; Lasnitschka, Georg

    2000-05-01

    A graphite furnace of the boat-in-tube type as electrothermal vaporizer (ETV) and an electrostatic precipitator were used for determining analyte transport efficiencies and dependencies on plant and cereal matrices, and on carrier elements. All analytical measurements were carried out with coherent forward scattering (CFS) using simultaneous multielement determinations. Transport efficiencies of up to 19% for Cu, 21% for Fe and Mn, and 36% for Pb from the ETV boat to the L'vov platform were obtained for the standard reference materials BCR CRM 281 rye grass, BCR CRM 189 wholemeal flour and NIST SRM 1567 wheat flour and multielement standard solutions containing approximately the same element ratios as certified for the solid samples. The analytical accuracy of the procedure including the ETV process and the electrostatic deposition was tested with Cu, Fe and Pb in BCR CRM 281, Cu, Fe and Mn in BCR CRM 189, and Fe and Mn in NIST SRM 1567 by weighing the solid sample onto the ETV-boat and calibrating against multielement standard solutions dosed into the ETV-boat as well. The analyte addition technique was tested with Cu, Fe and Mn in wholemeal flour. The deviations of the results were below 10% and the relative standard deviations (R.S.D.) values were typically 3-10%. The influence of added potassium and palladium nitrates as physical carriers on the transport efficiencies of Ag, Al, Cd, Cu, Fe, Ni, Pb and Zn standard solutions was investigated with simultaneous multielement determination. Using K and Pd as carriers increased transport efficiencies by factors up to 1.74 in comparison to measurements without an added carrier.

  5. A vapor generator for transonic flow visualization

    NASA Technical Reports Server (NTRS)

    Bruce, Robert A.; Hess, Robert W.; Rivera, Jose A., Jr.

    1989-01-01

    A vapor generator was developed for use in the NASA Langley Transonic Dynamics Tunnel (TDT). Propylene glycol was used as the vapor material. The vapor generator system was evaluated in a laboratory setting and then used in the TDT as part of a laser light sheet flow visualization system. The vapor generator provided satisfactory seeding of the air flow with visible condensate particles, smoke, for tests ranging from low subsonic through transonic speeds for tunnel total pressures from atmospheric pressure down to less than 0.1 atmospheric pressure.

  6. The development of a method for the determination of trace elements in fuel alcohol by electrothermal vaporization inductively coupled plasma mass spectrometry using external calibration

    NASA Astrophysics Data System (ADS)

    Saint'Pierre, Tatiana Dillenburg; Maranhão, Tatiane de Andrade; Frescura, Vera Lúcia Azzolin; Curtius, Adilson José

    2005-06-01

    A method for the determination of Ag, As, Cd, Cu, Co, Fe, Mn, Ni, Pb, Sn and Tl in fuel alcohol by electrothermal vaporization inductively coupled plasma mass spectrometry is proposed. The determinations were carried out by external calibration against ethanolic solutions, without a chemical modifier, employing the following pyrolysis and vaporization temperatures: 400 °C and 2300 °C for the more volatile analytes and 1000 °C and 2500 °C for the less volatile analytes. The determination of As, Cd, Pb, Sn and Tl was additionally carried out using Pd as modifier at 800 °C pyrolysis and 2400 °C vaporization temperatures. The temperatures were optimized through pyrolysis and vaporization curves. Seven common fuel ethanol, one fuel ethanol with additive and one anhydrous fuel ethanol sample have been analyzed. The measured concentrations were at the μg L -1 level or lower. Since there is no certified reference material for fuel ethanol, the accuracy of the method was checked by the recovery test, with recoveries from 75% to 124%. The limits of detection (LODs), in μg L -1, and the relative standard deviations for 5 replicates were, for the elements in the conditions without modifier: Ag: 0.015 and 9.1%, Co: 0.002 and 10%, Cu: 0.22 and 6.6%, Fe: 0.72 and 4.3%, Mn: 0.025 and 12%, Ni: 0.026 and 9.3%, and for the elements with Pd: As: 0.02 and 2.9%, Cd: 0.07 and 25%, Pb: 0.02 and 3.1%, Sn: 0.010 and 6.0%, Tl: 0.0008 and 2.5%. Electrothermal vaporization avoids the loading of the plasma with organics, allowing the analysis of fuel ethanol by ICP-MS with good accuracy and reasonable precision.

  7. Direct determination of trace rare earth elements in ancient porcelain samples with slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Xiang, Guoqiang; Jiang, Zucheng; He, Man; Hu, Bin

    2005-10-01

    A method for the direct determination of trace rare earth elements in ancient porcelain samples by slurry sampling fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry was developed with the use of polytetrafluoroethylene as fluorinating reagent. It was found that Si, as a main matrix element in ancient porcelain sample, could be mostly removed at the ashing temperature of 1200 °C without considerable losses of the analytes. However, the chemical composition of ancient porcelain sample is very complicated, which makes the influences resulting from other matrix elements not be ignored. Therefore, the matrix effect of ancient porcelain sample was also investigated, and it was found that the matrix effect is obvious when the matrix concentration was larger than 0.8 g l - 1 . The study results of particle size effect indicated that when the sample particle size was less than 0.057 mm, the particle size effect is negligible. Under the optimized operation conditions, the detection limits for rare earth elements by fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry were 0.7 ng g - 1 (Eu)-33.3 ng g - 1 (Nd) with the precisions of 4.1% (Yb)-10% (La) ( c = 1 μg l - 1 , n = 9). The proposed method was used to directly determine the trace rare earth elements in ancient porcelain samples produced in different dynasty (Sui, Ming and Qing), and the analytical results are satisfactory.

  8. Direct solid sampling system for electrothermal vaporization and its application to the determination of chlorine in nanopowder samples by inductively coupled plasma optical emission spectroscopy.

    PubMed

    Nakata, Kenichi; Hashimoto, Bunji; Uchihara, Hiroshi; Okamoto, Yasuaki; Ishizaka, Syoji; Fujiwara, Terufumi

    2015-06-01

    An electrothermal vaporization (ETV) system using a tungsten boat furnace (TBF) sample cuvette was designed for the direct determination of chlorine in metallic nanopowders and fine powder samples with detection by inductively coupled plasma optical emission spectroscopy (ICP-OES). A portion of a powder or particle sample was placed into a small tungsten sample cuvette and weighed accurately. A modifier solution of aqueous or alcoholic potassium hydroxide was added to it. Then, the cuvette was positioned on the TBF incorporated into the ETV apparatus. The analyte was vaporized and introduced into the ICP optical emission spectrometer with a carrier gas stream of argon and hydrogen. The metal samples were analyzed by using an external calibration curve prepared from aqueous standard solutions. Few chemical species including analyte and some chlorine-free species were introduced into the ICP, because the analyte has been separated from the matrix before introduction. Under such dry plasma conditions, the energy of plasma discharge was focused on the excitation of chlorine atoms, and as a result, lower detection limits were achieved. A detection limit of 170 ng g(-1) of chlorine in solid metal samples was established when 60 mg sample was used. The relative standard deviation for 16 replicate measurements obtained with 100 ng chlorine was 8.7%. Approximately 30 batches could be vaporized per hour. The analytical results for various nanopowders (iron (III) oxide, copper, silver, and gold) and metallic fine powder samples (silver and gold) are described. PMID:25863402

  9. Arsenic in marine tissues — The challenging problems to electrothermal and hydride generation atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Karadjova, Irina B.; Petrov, Panayot K.; Serafimovski, Ivan; Stafilov, Trajče; Tsalev, Dimiter L.

    2007-03-01

    Analytical problems in determination of arsenic in marine tissues are addressed. Procedures for the determination of total As in solubilized or extracted tissues with tetramethylammonium hydroxide and methanol have been elaborated. Several typical lyophilized tissues were used: NIST SRM 1566a 'Oyster Tissue', BCR-60 CRM 'Trace Elements in an Aquatic Plant ( Lagarosiphon major)', BCR-627 'Forms of As in Tuna Fish Tissue', IAEA-140/TM 'Sea Plant Homogenate', NRCC DOLT-1 'Dogfish Liver' and two representatives of the Black Sea biota, Mediterranean mussel ( Mytilus galloprovincialis) and Brown algae ( Cystoseira barbata). Tissues (nominal 0.3 g) were extracted in tetramethylammonium hydroxide (TMAH) 1 ml of 25% m/v TMAH and 2 ml of water) or 5 ml of aqueous 80% v/v methanol (MeOH) in closed vessels in a microwave oven at 50 °C for 30 min. Arsenic in solubilized or extracted tissues was determined by electrothermal atomic absorption spectrometry (ETAAS) after appropriate dilution (nominally to 25 ml, with further dilution as required) under optimal instrumental parameters (pyrolysis temperature 900 °C and atomization temperature 2100 °C) with 1.5 μg Pd as modifier on Zr-Ir treated platform. Platforms have been pre-treated with 2.7 μmol of zirconium and then with 0.10 μmol of iridium which served as a permanent chemical modifier in direct ETAAS measurements and as an efficient hydride sequestration medium in flow injection hydride generation (FI-HG)-ETAAS. TMAH and methanol extract 96-108% and 51-100% of As from CRMs. Various calibration approaches have been considered and critically evaluated. The effect of species-dependent slope of calibration graph or standard additions plot for total As determination in a sample comprising of several individual As species with different ETAAS behavior has been considered as a kind of 'intrinsic element speciation interference' that cannot be completely overcome by standard additions technique. Calibration by means of CRMs has

  10. Sensitive determination of bromine and iodine in aqueous and biological samples by electrothermal vaporization inductively coupled plasma mass spectrometry using tetramethylammonium hydroxide as a chemical modifier.

    PubMed

    Kataoka, Hiroko; Tanaka, Sachiko; Konishi, Chie; Okamoto, Yasuaki; Fujiwara, Terufumi; Ito, Kazuaki

    2008-06-01

    A procedure for the simultaneous determination of bromine and iodine by inductively coupled plasma (ICP) mass spectrometry was investigated. In order to prevent the decrease in the ionization efficiencies of bromine and iodine atoms caused by the introduction of water mist, electrothermal vaporization was used for sample introduction into the ICP mass spectrometer. To prevent loss of analytes during the drying process, a small amount of tetramethylammonium hydroxide solution was placed as a chemical modifier into the tungsten boat furnace. After evaporation of the solvent, the analytes instantly vaporized and were then introduced into the ICP ion source to detect the (79)Br(+), (81)Br(+), and (127)I(+) ions. By using this system, detection limits of 0.77 pg and 0.086 pg were achieved for bromine and iodine, respectively. These values correspond to 8.1 pg mL(-1) and 0.91 pg mL(-1) of the aqueous bromide and iodide ion concentrations, respectively, for a sampling volume of 95 microL. The relative standard deviations for eight replicate measurements were 2.2% and 2.8% for 20 pg of bromine and 2 pg of iodine, respectively. Approximately 25 batches were vaporizable per hour. The method was successfully applied to the analysis of various certified reference materials and practical situations as biological and aqueous samples. There is further potential for the simultaneous determination of fluorine and chlorine. PMID:18496883

  11. Simultaneous determination of bromine and chlorine in coal using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis.

    PubMed

    de Gois, Jefferson S; Pereira, Éderson R; Welz, Bernhard; Borges, Daniel L G

    2014-12-10

    A new method for the direct analysis of coal using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis was developed, aiming at the determination of Br and Cl. The procedure does not require any significant sample pretreatment and allows simultaneous determination of both elements to be carried out, requiring small mass aliquots of sample (about 0.5 mg). All operating parameters, including carrier gas flow-rate and RF power, were optimized for maximum sensitivity. The use of modifiers/aerosol carriers (Pd, Pd+Al and Pd+Ca) was evaluated, and the mixture of Pd and Ca was chosen, allowing pyrolysis and vaporization temperatures of 700°C and 1900°C, respectively. Chlorine was accurately determined using calibration against solid standards, whereas Br could also be determined using calibration against aqueous standard solutions. The limits of quantification were 0.03 μg g(-1) for Br and 7 μg g(-1) for Cl, and no spectral interferences were observed. PMID:25441883

  12. Assessment of the Halogen Content of Brazilian Inhalable Particulate Matter (PM10) Using High Resolution Molecular Absorption Spectrometry and Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry, with Direct Solid Sample Analysis.

    PubMed

    de Gois, Jefferson S; Almeida, Tarcisio S; Alves, Jeferson C; Araujo, Rennan G O; Borges, Daniel L G

    2016-03-15

    Halogens in the atmosphere play an important role in climate change and also represent a potential health hazard. However, quantification of halogens is not a trivial task, and methods that require minimum sample preparation are interesting alternatives. Hence, the aim of this work was to evaluate the feasibility of direct solid sample analysis using high-resolution continuum source molecular absorption spectrometry (HR-CS MAS) for F determination and electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICP-MS) for simultaneous Cl, Br, and I determination in airborne inhalable particulate matter (PM10) collected in the metropolitan area of Aracaju, Sergipe, Brazil. Analysis using HR-CS MAS was accomplished by monitoring the CaF molecule, which was generated at high temperatures in the graphite furnace after the addition of Ca. Analysis using ETV-ICP-MS was carried out using Ca as chemical modifier/aerosol carrier in order to avoid losses of Cl, Br, and I during the pyrolysis step, with concomitant use of Pd as a permanent modifier. The direct analysis approach resulted in LODs that were proven adequate for halogen determination in PM10, using either standard addition calibration or calibration against a certified reference material. The method allowed the quantification of the halogens in 14 PM10 samples collected in a northeastern coastal city in Brazil. The results demonstrated variations of halogen content according to meteorological conditions, particularly related to rainfall, humidity, and sunlight irradiation. PMID:26192198

  13. Electrothermal vaporization coupled with inductively coupled plasma array-detector mass spectrometry for the multielement analysis of Al2O3 ceramic powders

    SciTech Connect

    Peschel, Birgit U.; Andrade, Francisco J.; Wetzel, William C.; Schilling, G D.; Hieftje, Gary M.; Broekaert, Jose AC; Sperline, Roger; Denton, M BONNER.; Barinaga, Charles J.; Koppenaal, David W.

    2006-01-01

    An electrothermal vaporization (ETV) system useful for the analysis of solutions and slurries has been coupled with a sector-field inductively coupled plasma mass spectrometer (ICP-MS) equipped with an array detector. The ability of this instrument to record the transient signals produced in ETV-ICP-MS is demonstrated. Detection limits for Mn, Fe, Co, Ni, Cu, Zn and Ga are in the range of 4-60 pg ?L-1 for aqueous solutions and in the low ?g g-1 range for the analysis of 10 mg mL-1 slurries of Al2O3 powders. The dynamic ranges measured for Fe, Cu and Ga spanned 3-5 orders of magnitude when the detector was operated in the low-gain mode and appear to be limited by the ETV system. Trace amounts of Fe, Cu and Ga could be directly determined in Al2O3 powders at the 2-270 ?g g-1 level without the use of thermochemical reagents. The results well agree with literature values for Fe, whereas deviations of 30-50% at the 2-90 ?g g-1 level for Cu and Ga were found.

  14. Imaging of elements in leaves of tobacco by solid sampling-electrothermal vaporization-inductively coupled plasma-optical emission spectrometry

    NASA Astrophysics Data System (ADS)

    Masson, Pierre

    2014-12-01

    Plants take up and store elements according to the environment in which they are growing. Because plants are at the base of the food chain, the determination of essential elements or toxic elements in plant materials is of importance. However, it is assumed that the element content determined on selected tissues may provide more specific information than that derived from the whole plant analysis. In this work, we assessed the feasibility of solid sampling-electrothermal vaporization-inductively coupled plasma-optical emission spectrometry analyses for quantitative imaging of Cd and Mg in plant leaves. Leaves of tobacco (Nicotiana tabacum) were selected to be used as samples. To produce a two dimensional image, sections cut from leaf samples were analyzed. Cellulose doped with multi-element solution standards was used as calibration samples. Two certified reference materials (NIST SRM 1547 Peach Leaves and NIST SRM 1573a Tomato leaves) were used to verify the accuracy of measurements with good agreement between the measured concentrations and the certified values. Quantitative imaging revealed the inhomogeneous distribution of the selected elements. Excess of Cd and Mg tended to be focused on peripheral regions and the tip of the leaf.

  15. Application of direct solid sample analysis for the determination of chlorine in biological materials using electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    de Gois, Jefferson Santos; Pereira, Éderson R.; Welz, Bernhard; Borges, Daniel L. G.

    2015-03-01

    This work describes a methodology developed to carry out Cl determination in biological materials using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis. The solid samples were directly weighed into graphite 'cups' and inserted into the graphite furnace. The RF power and the carrier gas flow rate were optimized at 1300 W and 0.7 L min- 1, respectively. Calibration could be carried out using aqueous standard solutions with pre-dried modifiers (Pd + Nd or Pd + Ca) or using solid certified reference materials with the same pre-dried modifiers or without the use of modifiers. The limit of quantification was determined as 5 μg g- 1 under optimized conditions and the Cl concentration was determined in five certified reference materials with certified concentrations for Cl, in addition to three certified reference materials, for which certified values for Cl were unavailable; in the latter case, the results were compared with those obtained using high-resolution continuum source molecular absorption spectrometry. Good agreement at a 95% statistical confidence level was achieved between determined and certified or reference values.

  16. Analysis of fish otoliths by electrothermal vaporization inductively coupled plasma mass spectrometry: aspects of precipitating otolith calcium with hydrofluoric acid for trace element determination.

    PubMed

    Arslan, Zikri

    2005-03-15

    A method is developed for determination of trace elements, including Ag, As, Cd, Co, Cr, Cu, Mn, Ni, Se, Tl and Zn, in fish otoliths by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). Hydrofluoric acid was used to precipitate calcium resulting from acid dissolution of otolith calcium carbonate. Initial acidity of the sample solution influenced the precipitation efficiency of calcium fluoride. Up to 99.5% of Ca was precipitated in solutions that contained less than 2% (v/v) HNO(3). Recoveries of the elements obtained from spiked artificial otolith solutions were between 90 and 103%. Stabilization of the elements within the ETV cell was achieved with 0.3mug Pd/0.2mug Rh chemical modifier that also afforded optimum sensitivity for multielement determination. The method was validated by the analysis of a fish otolith reference material (CRM) of emperor snapper, and then applied to the determination of the trace elements in otoliths of several fish species captured in Raritan Bay, New Jersey. Results indicated that fish physiology and biological processes could influence the levels of Cu, Mn, Se and Zn in the otoliths of fish inhabiting a similar aqueous environment. Otolith concentrations of Cr and Ni did not show any significant differences among different species. Concentrations for Ag, As, Cd, Co and Tl were also not significantly different, but were very low indicating low affinity of otolith calcium carbonate to these elements. PMID:18969949

  17. Estimating evaporative vapor generation from automobiles based on parking activities.

    PubMed

    Dong, Xinyi; Tschantz, Michael; Fu, Joshua S

    2015-07-01

    A new approach is proposed to quantify the evaporative vapor generation based on real parking activity data. As compared to the existing methods, two improvements are applied in this new approach to reduce the uncertainties: First, evaporative vapor generation from diurnal parking events is usually calculated based on estimated average parking duration for the whole fleet, while in this study, vapor generation rate is calculated based on parking activities distribution. Second, rather than using the daily temperature gradient, this study uses hourly temperature observations to derive the hourly incremental vapor generation rates. The parking distribution and hourly incremental vapor generation rates are then adopted with Wade-Reddy's equation to estimate the weighted average evaporative generation. We find that hourly incremental rates can better describe the temporal variations of vapor generation, and the weighted vapor generation rate is 5-8% less than calculation without considering parking activity. PMID:25818089

  18. Determination of methylmercury by electrothermal atomic absorption spectrometry using headspace single-drop microextraction with in situ hydride generation

    NASA Astrophysics Data System (ADS)

    Gil, Sandra; Fragueiro, Sandra; Lavilla, Isela; Bendicho, Carlos

    2005-01-01

    A new method is proposed for preconcentration and matrix separation of methylmercury prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). Generation of methylmercury hydride (MeHgH) from a 5-ml solution is carried out in a closed vial and trapped onto an aqueous single drop (3-μl volume) containing Pd(II) or Pt(IV) (50 and 10 mg/l, respectively). The hydrogen evolved in the headspace (HS) after decomposition of sodium tetrahydroborate (III) injected for hydride generation caused the formation of finely dispersed Pd(0) or Pt(0) in the drop, which in turn, were responsible for the sequestration of MeHgH. A preconcentration factor of ca. 40 is achieved with both noble metals used as trapping agents. The limit of detection of methylmercury was 5 and 4 ng/ml (as Hg) with Pd(II) or Pt(IV) as trapping agents, and the precision expressed as relative standard deviation was about 7%. The preconcentration system was fully characterised through optimisation of the following variables: Pd(II) or Pt(IV) concentration in the drop, extraction time, pH of the medium, temperatures of both sample solution and drop, concentration of salt in the sample solution, sodium tetrahydroborate (III) concentration in the drop and stirring rate. The method has been successfully validated against two fish certified reference materials (CRM 464 tuna fish and CRM DORM-2 dogfish muscle) following selective extraction of methylmercury in 2 mol/l HCl medium.

  19. Capillary microextraction combined with fluorinating assisted electrothermal vaporization inductively coupled plasma optical emission spectrometry for the determination of trace lanthanum, europium, dysprosium and yttrium in human hair.

    PubMed

    Wu, Shaowei; Hu, Chengguo; He, Man; Chen, Beibei; Hu, Bin

    2013-10-15

    In this work, a congo red modified single wall carbon nanotubes (CR-SWCNTs) coated fused-silica capillary was prepared and used for capillary microextraction (CME) of trace amounts of lanthanum (La), europium (Eu), dysprosium (Dy) and yttrium (Y) in human hair followed by fluorinating assisted electrothermal vaporization-inductively coupled plasma-optical emission spectrometry (FETV-ICP-OES) determination. The adsorption properties and stability of the prepared CR-SWCNTs coated capillary along with the various factors affecting the separation/preconcentration of La, Eu, Dy and Y by CME were investigated in detail. Under the optimized conditions, with a consumption of 2 mL sample solution, a theoretical enrichment factor of 50 and a detection limit (3σ) of 0.12 ng mL(-1) for La, 0.03 ng mL(-1) for Eu, 0.11 ng mL(-1) for Dy and 0.03 ng mL(-1) for Y were obtained, respectively. The preparation reproducibility of the CR-SWCNTs coated capillary was investigated and the relative standard deviations (RSDs) were ranging from 4.1% (Eu) to 4.4% (La) (CLa, Dy=1.4 ng mL(-1); CY, Eu=0.25 ng mL(-1), n=7) in one batch, and from 5.7% (Eu) to 6.1% (Y) (CLa, Dy=1.4 ng mL(-1); CY, Eu=0.25 ng mL(-1), n=5) among different batches. The proposed method was applied to the analysis of real-world human hair sample and the recoveries for the spiked sample were in the range of 93-105%. The method was also applied to the determination of La, Eu, Dy and Y in Certified Reference Material of GBW07601 human hair, and the determined values were in good agreement with the certified values. PMID:24054601

  20. Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of Cr, Fe, Cu, Zn and Se in cereals

    NASA Astrophysics Data System (ADS)

    Huang, Shih-Yi; Jiang, Shiuh-Jen; Sahayam, A. C.

    2014-11-01

    Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Cr, Fe, Cu, Zn and Se in several cereal samples. Thioacetamide was used as the modifier to enhance the ion signals. The background ions at the masses of interest were reduced in intensity significantly by using 1.0 mL min- 1 methane (CH4) as reaction cell gas in the dynamic reaction cell (DRC). Since the sensitivities of Cr, Fe, Cu, Zn and Se in different matrices were quite different, standard addition and isotope dilution methods were used for the determination of Cr, Fe, Cu, Zn and Se in these cereal samples. The method detection limits estimated from standard addition curves were about 1, 10, 4, 12 and 2 ng g- 1 for Cr, Fe, Cu, Zn and Se, respectively, in original cereal samples. This procedure has been applied to the determination of Cr, Fe, Cu, Zn and Se whose concentrations are in μg g- 1 (except Cr and Se) in standard reference materials (SRM) of National institute of standards and technology (NIST), NIST SRM 1568a Rice Flour and NIST SRM 1567a Wheat Flour and two cereal samples purchased from a local market. The analysis results of reference materials agreed with certified values at 95% confidence level according to Student's T-test. The results for the real world cereal samples were also found to be in good agreement with the pneumatic nebulization DRC ICP-MS results of the sample solutions.

  1. Phase transfer hollow fiber liquid phase microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of trace heavy metals in environmental and biological samples.

    PubMed

    Guo, Xueqin; He, Man; Chen, Beibei; Hu, Bin

    2012-11-15

    A new method of phase transfer hollow fiber liquid phase microextraction (PT-HF-LPME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) has been developed for the determination of trace Co, Pd, Cd and Bi in environmental and biological samples. In PT-HF-LPME, an intermediate solvent (1-butanol) was added into the sample solution to ensure the maximum contact area between the target metal ions and the chelating reagent (8-hydroxyquinoline, 8-HQ), which accelerated the formation of 8-HQ-metal complexes and their subsequent extraction by extraction solvent (toluene). The experimental parameters affecting the extraction efficiency of PT-HF-LPME for the target metals were studied by simplex optimization and orthogonal array design (OAD) experiments. Under the optimized conditions, the enrichment factors for Co, Pd, Cd and Bi were 110, 393, 121 and 111-fold, respectively, the limits of detection (LODs, 3σ) ranged from 3.7 to 8.3 ng L(-1). The relative standard deviations (RSDs, c=0.5 ng mL(-1), n=7) were 8.7, 6.2, 12.4 and 12.9% for Co, Pd, Cd and Bi, respectively. To validate the accuracy of the proposed method, two Certified Reference Materials of GSBZ50009-88 Environment Water and GBW09103 Human Urine were analyzed, and the results obtained for Cd were in good agreement with the certified values. Finally, the developed method was successfully applied to the analysis of Co, Pd, Cd and Bi in lake water and human urine samples. PMID:23158357

  2. Ultra-trace determination of gold nanoparticles in environmental water by surfactant assisted dispersive liquid liquid microextraction coupled with electrothermal vaporization-inductively coupled plasma-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Liu, Ying; He, Man; Chen, Beibei; Hu, Bin

    2016-08-01

    A new method by coupling surfactant assisted dispersive liquid liquid microextraction (SA-DLLME) with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) was proposed for the analysis of gold nanoparticles (AuNPs) in environmental water samples. Effective separation of AuNPs from ionic gold species was achieved by using sodium thiosulphate as a complexing agent. Various experimental parameters affecting SA-DLLME of AuNPs, such as the organic solvent, organic solvent volume, pH of the sample, the kind of surfactant, surfactant concentration, vortex time, speed of centrifugation, centrifugation time, and different coating as well as sizes of AuNPs were investigated carefully. Furthermore, the interference of coexisting ions, dissolved organic matter (DOM) and other metal nanoparticles (NPs) were studied. Under the optimal conditions, a detection limit of 2.2 ng L- 1 and an enrichment factor of 152-fold was achieved for AuNPs, and the original morphology of the AuNPs could be maintained during the extraction process. The developed method was successfully applied for the analysis of AuNPs in environmental water samples, including tap water, the East Lake water, and the Yangtze River water, with recoveries in the range of 89.6-102%. Compared with the established methods for metal NPs analysis, the proposed method has the merits of simple and fast operation, low detection limit, high selectivity, good tolerance to the sample matrix and no digestion or dilution required. It provides an efficient quantification methodology for monitoring AuNPs' pollution in the environmental water and evaluating its toxicity.

  3. Boiler for generating high quality vapor

    NASA Technical Reports Server (NTRS)

    Gray, V. H.; Marto, P. J.; Joslyn, A. W.

    1972-01-01

    Boiler supplies vapor for use in turbines by imparting a high angular velocity to the liquid annulus in heated rotating drum. Drum boiler provides a sharp interface between boiling liquid and vapor, thereby, inhibiting the formation of unwanted liquid droplets.

  4. Simultaneous speciation of inorganic arsenic, selenium and tellurium in environmental water samples by dispersive liquid liquid microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry.

    PubMed

    Liu, Ying; He, Man; Chen, Beibei; Hu, Bin

    2015-09-01

    A new method based on dispersive liquid liquid microextraction (DLLME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) was developed for the simultaneous speciation of inorganic arsenic (As), selenium (Se) and tellurium (Te) with sodium diethyldithiocarbamate (DDTC) as both chelating reagent and chemical modifier. As(III), Se(IV) and Te(IV) were transformed into DDTC-chelates at pH 7 and extracted into the fine droplets formed by injecting the binary solution of bromobenzene (extraction solvent) and methanol (dispersive solvent) into the sample solution. After phase separation by centrifugation, As(III), Se(IV) and Te(IV) preconcentrated in the organic phase were determined by ETV-ICP-MS. Total inorganic As, Se and Te were obtained by reducing As(V), Se(VI) and Te(VI) to As(III), Se(IV) and Te(IV) with L-cysteine, which were then subjected to the same DLLME-ETV-ICP-MS process. The concentration of As(V), Se(VI), Te(VI) were calculated by subtracting the concentration of As(III), Se(IV) and Te(IV) from the total inorganic As, Se and Te, respectively. The main factors affecting the microextraction efficiency and the vaporization behavior of target species were investigated in detail. Under the optimal conditions, the limits of detection were 2.5, 8.6 and 0.56 ng L(-1) for As(III), Se(IV) and Te(IV), respectively, with the relative standard deviations (n=7) of 8.5-9.7%. The developed method was applied to the speciation of inorganic As, Se and Te in Certified Reference Materials of GSBZ50004-88, GBW(E)080395 and GBW(E)080548 environmental waters, and the determined values are in good agreement with the certified values. The method was also successfully applied to the simultaneous speciation of inorganic As, Se and Te in different environmental water samples with the recoveries in the range of 86.3-107% for the spiked samples. PMID:26003714

  5. Means and method for vapor generation

    DOEpatents

    Carlson, Larry W.

    1984-01-01

    A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid--starting as "feedwater" heating where no vapors are present, progressing to "nucleate" heating where vaporization begins and some vapors are present, and concluding with "film" heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10-30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

  6. Means and method for vapor generation

    DOEpatents

    Carlson, L.W.

    A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid - starting as feedwater heating where no vapors are present, progressing to nucleate heating where vaporization begins and some vapors are present, and concluding with film heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10 to 30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

  7. Generation and characterization of aerosols and vapors for inhalation experiments.

    PubMed Central

    Tillery, M I; Wood, G O; Ettinger, H J

    1976-01-01

    Control of aerosol and vapor characteristics that affect the toxicity of inhaled contaminants often determines the methods of generating exposure atmospheres. Generation methods for aerosols and vapors are presented. The characteristics of the resulting exposure atmosphere and the limitations of the various generation methods are discussed. Methods and instruments for measuring the airborne contaminant with respect to various charcteristics are also described. PMID:797565

  8. Determination of arsenic in geological materials by electrothermal atomic-absorption spectrometry after hydride generation

    USGS Publications Warehouse

    Sanzolone, R.F.; Chao, T.T.; Welsch, E.P.

    1979-01-01

    Rock and soil samples are decomposed with HClO4-HNO3; after further treatment, arsine is generated and absorbed in a dilute silver nitrate solution. Aliquots of this solution are injected into a carbon rod atomizer. Down to 1 ppm As in samples can be determined and there are no significant interferences, even from chromium in soils. Good results were obtained for geochemical reference samples. ?? 1979.

  9. Solar vapor generation enabled by nanoparticles.

    PubMed

    Neumann, Oara; Urban, Alexander S; Day, Jared; Lal, Surbhi; Nordlander, Peter; Halas, Naomi J

    2013-01-22

    Solar illumination of broadly absorbing metal or carbon nanoparticles dispersed in a liquid produces vapor without the requirement of heating the fluid volume. When particles are dispersed in water at ambient temperature, energy is directed primarily to vaporization of water into steam, with a much smaller fraction resulting in heating of the fluid. Sunlight-illuminated particles can also drive H(2)O-ethanol distillation, yielding fractions significantly richer in ethanol content than simple thermal distillation. These phenomena can also enable important compact solar applications such as sterilization of waste and surgical instruments in resource-poor locations. PMID:23157159

  10. Dynamic headspace generation and quantitation of triacetone triperoxide vapor.

    PubMed

    Giordano, Braden C; Lubrano, Adam L; Field, Christopher R; Collins, Greg E

    2014-02-28

    Two methods for quantitation of triacetone triperoxide (TATP) vapor using a programmable temperature vaporization (PTV) inlet coupled to a gas chromatography/mass spectrometer (GC/MS) have been demonstrated. The dynamic headspace of bulk TATP was mixed with clean humid air to produce a TATP vapor stream. Sampling via a heated transfer line to a PTV inlet with a Tenax-TA™ filled liner allowed for direct injection of the vapor stream to a GC/MS for vapor quantitation. TATP was extracted from the vapor stream and subsequently desorbed from the PTV liner for splitless injection on the GC column. Calibration curves were prepared using solution standards with a standard split/splitless GC inlet for quantitation of the TATP vapor. Alternatively, vapor was sampled onto a Tenax-TA™ sample tube and placed into a thermal desorption system. In this instance, vapor was desorbed from the tube and subsequently trapped on a liquid nitrogen cooled PTV inlet. Calibration curves for this method were prepared from direct liquid injection of standards onto samples tube with the caveat that a vacuum is applied to the tube during deposition to ensure that the volatile TATP penetrates into the tube. Vapor concentration measurements, as determined by either GC/MS analysis or mass gravimetry of the bulk TATP, were statistically indistinguishable. Different approaches to broaden the TATP vapor dynamic range, including diluent air flow, sample chamber temperature, sample vial orifice size, and sample size are discussed. Vapor concentrations between 50 and 5400ngL(-1) are reported, with stable vapor generation observed for as long as 60 consecutive hours. PMID:24508355

  11. Arsenic speciation in environmental samples by hydride generation and electrothermal atomic absorption spectrometry.

    PubMed

    Anawar, Hossain Md

    2012-01-15

    For the past few years many studies have been performed to determine arsenic (As) speciation in drinking water, food chain and other environmental samples due to its well-recognized carcinogenic and toxic effects relating to its chemical forms and oxidation states. This review provides an overview of analytical methods, preconcentration and separation techniques, developed up to now, using HGAAS and ETAAS for the determination of inorganic As and organoarsenic species in environmental samples. Specific advantages, disadvantages, selectivity, sensitivity, efficiency, rapidity, detection limit (DL), and some aspects of recent improvements and modifications for different analytical and separation techniques, that can define their application for a particular sample analysis, are highlighted. HG-AAS has high sensitivity, selectivity and low DL using suitable separation techniques; and it is a more suitable, affordable and much less expensive technique than other detectors. The concentrations of HCl and NaBH(4) have a critical effect on the HG response of As species. Use of l-cysteine as pre-reductant is advantageous over KI to obtain the same signal response for different As species under the same, optimum and mild acid concentration, and to reduce the interference of transition metals on the arsine generation. Use of different pretreatment, digestion, separation techniques and surfactants can determine As species with DL from ngL(-1) to μgL(-1). Out of all the chromatographic techniques coupled with HGAAS/ETAAS, ion-pair reversed-phase chromatography (IP-RP) is the most popular due to its higher separation efficiency, resolution selectivity, simplicity, and ability to separate up to seven As species for both non-ionic and ionic compounds in a signal run using the same column and short time. However, a combination of anion- and cation-exchange chromatography seems the most promising for complete resolution up to eight As species. The ETAAS method using different

  12. Calibration of an explosives vapor generator based on vapor diffusion from a condensed phase

    SciTech Connect

    Parmeter, J.E.; Rhykerd, L. Jr.; Conrad, F.J.; Tiano, G.S.; Preston, D.; Eiceman, G.A.; Arnold, J.T.

    1995-12-31

    Development of a vapor generator for consistently producing accurate amounts of vapor from low vapor pressure explosive materials is a pressing need within the explosives detection community. Of particular importance for reproducibility and widespread acceptance of results is the correlation of such a vapor generator to a National Institute of Standards and Technology (NIST) mass standard. This paper describes an explosives vapor generator recently developed at Varian in which a solid explosive sample in a precision bore glass tube is put in an oven at constant temperature, and vapor diff-using from the top of the tube is entrained in a carrier gas flow. The rate of vapor output is thus dependent on both the equilibrium vapor pressure of the solid at oven temperature and the rate of diffusion up the length of the tube. Correlation to a NIST mass standard is achieved by periodic weighing of the sample tube on a microbalance. We report results obtained with the explosives TNT and RDX. Results for TNT show that the mass output rate is constant over hundreds of hours of continuous use, with outputs of {approximately} 10--2000 pg/sec for oven temperatures in the range of 60--120{degrees}C. Both the mass loss experiments and calibration with an ion mobility spectrometer (IMS) give a TNT mass output value of 85 pg/sec at 79{degrees}C, and this result is supported by transport theory calculations. Mass loss curves for RDX are also linear with time, and show the expected exponential increase of mass output with oven temperature.

  13. Spectral probing of impact-generated vapor in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Schultz, Peter H.; Eberhardy, Clara A.

    2015-03-01

    High-speed spectra of hypervelocity impacts at the NASA Ames Vertical Gun Range (AVGR) captured the rapidly evolving conditions of impact-generated vapor as a function of impact angle, viewpoint, and time (within the first 50 μs). Impact speeds possible at the AVGR (<7 km/s) are insufficient to induce significant vaporization in silicates, other than the high-temperature (but low-mass) jetting component created at first contact. Consequently, this study used powdered dolomite as a proxy for surveying the evolution and distribution of chemical constituents within much longer lasting vapor. Seven separate telescopes focused on different portions of the impact vapor plume and were connected through quartz fibers to two 0.35 cm monochromaters. Quarter-space experiments reduced the thermal background and opaque phases due to condensing particles and heated projectile fragments while different exposure times isolated components passing through different the fields of view, both above and below the surface within the growing transient cavity. At early times (<5 μs), atomic emission lines dominate the spectra. At later times, molecular emission lines dominate the composition of the vapor plume along a given direction. Layered targets and target mixtures isolated the source and reveal that much of the vaporization comes from the uppermost surface. Collisions by projectile fragments downrange also make significant contributions for impacts below 60° (from the horizontal). Further, impacts into mixtures of silicates with powdered dolomite reveal that frictional heating must play a role in vapor production. Such results have implications for processes controlling vaporization on planetary surfaces including volatile release, atmospheric evolution (formation and erosion), vapor generated by the Deep Impact collision, and the possible consequences of the Chicxulub impact.

  14. Electrolysis cell functions as water vapor dehumidifier and oxygen generator

    NASA Technical Reports Server (NTRS)

    Clifford, J. E.

    1971-01-01

    Water vapor is absorbed in hygroscopic electrolyte, and oxygen generated by absorbed water electrolysis at anode is added simultaneously to air stream. Cell applications include on-board aircraft oxygen systems, portable oxygen generators, oxygen concentration requirements, and commercial air conditioning and dehumidifying systems.

  15. Techniques for the generation and monitoring of vapors

    SciTech Connect

    Nelson, G.O.

    1981-02-06

    Controlled test atmospheres can be produced using a variety of techniques. Gases are usually generated by using flow dilution methods while vapors are produced by using solvent injection and vaporization, saturation, permeation and diffusion techniques. The resulting gas mixtures can be monitored and measured using flame ionization, photoionization, electrochemical and infrared analytical systems. An ideal system for the production of controlled test atmospheres would not only be able to generate controlled test atmospheres, but also monitor all pertinent environmental parameters, such as temperature, humidity, and air flow.

  16. Porous graphitized carbon for adsorptive removal of benzene and the electrothermal regeneration.

    PubMed

    Li, Jinjun; Lu, Renjie; Dou, Baojuan; Ma, Chunyan; Hu, Qiuhong; Liang, Yan; Wu, Feng; Qiao, Shizhang; Hao, Zhengping

    2012-11-20

    Graphitized carbons with mesoporous and macroporous structures were synthesized by a facile template-catalysis procedure using resorcinol and formaldehyde as carbon precursors and particulate hydrated metal oxides as both template and catalyst precursors. The materials were used as novel adsorbents for low-concentration benzene vapor. Furthermore, on the basis of the good electrical conductivities associated with the graphitized structures, an electrothermal desorption technique, which involved passing electric currents through the adsorbents to generate Joule heat, was employed to regenerate the saturated adsorbents and produce enriched benzene vapors. In comparison to microporous activated carbon, the porous graphitized carbons could afford a much quicker and more efficient regeneration by electrothermal desorption technique due to their enhanced conductivity and larger pore sizes. In addition, the concentration of the desorbed organics could be controlled by adjusting the applied voltages, which might be interesting for practical secondary treatment. It is promising that the joint utilization of porous graphitized carbon adsorbents and electrothermal desorption technique might develop effective and energy-saving processes for VOCs removal. PMID:23092151

  17. Hollow Mesoporous Plasmonic Nanoshells for Enhanced Solar Vapor Generation.

    PubMed

    Zielinski, Marcin S; Choi, Jae-Woo; La Grange, Thomas; Modestino, Miguel; Hashemi, Seyyed Mohammad Hosseini; Pu, Ye; Birkhold, Susanne; Hubbell, Jeffrey A; Psaltis, Demetri

    2016-04-13

    In the past decade, nanomaterials have made their way into a variety of technologies in solar energy, enhancing the performance by taking advantage of the phenomena inherent to the nanoscale. Recent examples exploit plasmonic core/shell nanoparticles to achieve efficient direct steam generation, showing great promise of such nanoparticles as a useful material for solar applications. In this paper, we demonstrate a novel technique for fabricating bimetallic hollow mesoporous plasmonic nanoshells that yield a higher solar vapor generation rate compared with their solid-core counterparts. On the basis of a combination of nanomasking and incomplete galvanic replacement, the hollow plasmonic nanoshells can be fabricated with tunable absorption and minimized scattering. When exposed to sun light, each hollow nanoshell generates vapor bubbles simultaneously from the interior and exterior. The vapor nucleating from the interior expands and diffuses through the pores and combines with the bubbles formed on the outer wall. The lack of a solid core significantly accelerates the initial vapor nucleation and the overall steam generation dynamics. More importantly, because the density of the hollow porous nanoshells is essentially equal to the surrounding host medium these particles are much less prone to sedimentation, a problem that greatly limits the performance and implementation of standard nanoparticle dispersions. PMID:26918518

  18. Novel bimodal porous N-(2-aminoethyl)-3-aminopropyltrimethoxysilane-silica monolithic capillary microextraction and its application to the fractionation of aluminum in rainwater and fruit juice by electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zheng, Fei; Hu, Bin

    2008-01-01

    A novel bimodal porous N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS)-silica monolithic capillary was prepared by sol-gel technology, and used as capillary microextraction (CME) column for aluminum fractionation by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV)-ICP-MS with the use of polytetrafluoroethylene (PTFE) slurry as fluorinating agent. The extraction behaviors of different Al species were studied and it was found that in the pH range of 4-7, labile monomeric Al (free Al 3+, Al-OH and Al-F) could be retained quantitatively on the monolithic capillary, while non-labile monomeric Al (Al-Cit and Al-EDTA) passed through the capillary directly. The labile monomeric Al retained on monolithic capillary was eluted with 10 μL 1 mol L - 1 HCl and the elution was introduced into the ETV for fluorination assisted ETV-ICP-MS determination. The total monomeric Al fraction was also determined by AAPTS-silica monolithic CME-fluorination-assisted electrothermal vaporization (FETV)-ICP-MS after the sample solution was adjusted to pH 8.8. Non-labile monomeric Al was obtained by subtracting labile monomeric Al from the total monomeric Al. Under the optimized conditions, the relative standard deviation (R.S.D) was 6.2% ( C = 1 μg L - 1 , n = 7; sample volume, 5 mL), and the limit of detection was 1.6 ng L - 1 for Al with an enrichment factor of 436 fold and a sampling frequency of 9 h - 1 . The prepared AAPTS-silica monolithic capillary showed an excellent pH tolerance and solvent stability and could be used for more than 250 times without decreasing adsorption efficiency. The developed method was applied to the fraction of Al in rainwater and fruit juice, and the results demonstrated that the established system had advantages over the existing 8-hydroxyquinoline (8-HQ) chelating system for Al fractionation such as wider pH range, higher tolerance of interference and better regeneration.

  19. Vapor-Generator Wand Helps To Reveal Airflow Patterns

    NASA Technical Reports Server (NTRS)

    Robelen, David B.

    1993-01-01

    In vapor-generator wand, liquid propylene glycol flows into electrically heated stainless-steel tube. Liquid boils in heated tube, and emerging vapor forms dense, smoke-like fog used to make airflow patterns visible. Built in variety of sizes, suitable for uses ranging from tabletop demonstrations to research in wind tunnels. For best viewing, plume illuminated by bright, focused incandescent spotlight at right angle to viewing direction. Viewing further enhanced by coating walls of test chamber with flat, dark color to minimize reflections and increase contrast.

  20. Direct atomic absorption determination of cadmium and lead in strongly interfering matrices by double vaporization with a two-step electrothermal atomizer

    NASA Astrophysics Data System (ADS)

    Grinshtein, Ilia L.; Vilpan, Yuri A.; Saraev, Alexei V.; Vasilieva, Lubov A.

    2001-03-01

    Thermal pretreatment of a sample using double vaporization in a two-step atomizer with a purged vaporizer makes possible the direct analysis of samples with strongly interfering matrices including solids. A porous-graphite capsule or a filter inserted into the vaporizer is used for solid sample analysis. The technique was used for the direct determination of Cd and Pb in human urine, potatoes, wheat, bovine liver, milk powder, grass-cereal mixtures, caprolactam, bituminous-shale and polyvinyl chloride plastic without chemical modification or any other sample pretreatment.

  1. Dual extraction based on solid phase extraction and solidified floating organic drop microextraction for speciation of arsenic and its distribution in tea leaves and tea infusion by electrothermal vaporization ICP-MS.

    PubMed

    Chen, Shizhong; Li, Jianfen; Lu, Dengbo; Zhang, Yan

    2016-11-15

    A dual extraction based on solid phase extraction (SPE) and solidified floating organic drop microextraction (SFODME) was developed for As species in tea leaves and tea infusion by electrothermal vaporization inductively coupled plasma mass spectrometry, including total, suspended, soluble, organic and inorganic As as well as As(III) and As(V). In SPE step, titanium dioxide nanotubes were used for preconcentration of analytes and removal of sample matrix. Elution solution from SPE was employed for further preconcentration and separation of analytes with SFODME. Under optimal conditions, detection limits of this method were 0.046 and 0.072pgmL(-1) with relative standard deviations of 6.3% and 5.8% for As(III) and As(V) (n=9, c=1.0ngmL(-1)), respectively. A preconcentration factor of 500-fold was achieved for As(III) and As(V). This method was successfully applied for analysis of speciation of arsenic and its distribution in tea leaves, tea infusion and certified reference material of tea leaves. PMID:27283691

  2. Plasmonic Nanobubbles as Transient Vapor Nanobubbles Generated Around Plasmonic Nanoparticles

    PubMed Central

    Lukianova-Hleb, Ekaterina; Hu, Ying; Latterini, Loredana; Tarpani, Luigi; Lee, Seunghyun; Drezek, Rebekah A.; Hafner, Jason H.; Lapotko, Dmitri O.

    2010-01-01

    We have used short laser pulses to generate transient vapor nanobubbles around plasmonic nanoparticles. The photothermal, mechanical and optical properties of such bubbles were found to be different from those of plasmonic nanoparticle and vapor bubbles as well. This phenomena was considered as a new complex nanosystem – plasmonic nanobubble (PNB). Mechanical and optical scattering properties of PNB depended upon the nanoparticle surface and heat capacity, clusterization state, and the optical pulse length. The generation of the PNB required much higher laser pulse fluence thresholds than the explosive boiling level, and was characterized by the relatively high lower threshold of the minimal size (lifetime) of PNB. Optical scattering by PNB and its diameter (measured as the lifetime) has been varied with the fluence of laser pulse and this has demonstrated the tunable nature of PNB. PMID:20307085

  3. Plasmonic nanobubbles as transient vapor nanobubbles generated around plasmonic nanoparticles.

    PubMed

    Lukianova-Hleb, Ekaterina; Hu, Ying; Latterini, Loredana; Tarpani, Luigi; Lee, Seunghyun; Drezek, Rebekah A; Hafner, Jason H; Lapotko, Dmitri O

    2010-04-27

    We have used short laser pulses to generate transient vapor nanobubbles around plasmonic nanoparticles. The photothermal, mechanical, and optical properties of such bubbles were found to be different from those of plasmonic nanoparticle and vapor bubbles, as well. This phenomenon was considered as a new complex nanosystem-plasmonic nanobubble (PNB). Mechanical and optical scattering properties of PNB depended upon the nanoparticle surface and heat capacity, clusterization state, and the optical pulse length. The generation of the PNB required much higher laser pulse fluence thresholds than the explosive boiling level and was characterized by the relatively high lower threshold of the minimal size (lifetime) of PNB. Optical scattering by PNB and its diameter (measured as the lifetime) has been varied with the fluence of laser pulse, and this has demonstrated the tunable nature of PNB. PMID:20307085

  4. Studies of interfaces and vapors with Optical Second Harmonic Generation

    SciTech Connect

    Mullin, C. S.

    1993-12-01

    Optical Second Harmonic Generation (SHG) has been applied to the study of soap-like molecules adsorbed to the water-air interface. By calibrating the signal from a soluble monolayer with that of an insoluble homolog, absolute measurements of the surface density could be obtained and related to the bulk concentration and surface tension. We could then demonstrate that the soluble surfactant forms a single monolayer at the interface. Furthermore, it deviates significantly from the ideal case in that its activity coefficients are far from 1, yet those coefficients remain constant over a broad range of surface pressures. We present evidence of a first-order phase transition taking place during the adsorption of this soluble monolayer. We consider the effects of the non-ideal behavior and the phase transition on the microscopic model of adsorption, and formulate an alternative to the Langmuir picture of adsorption which is just as simple, yet it can more easily allow for non-ideal behavior. The second half of this thesis considers the problem of SHG in bulk metal vapors. The symmetry of the vapor forbids SHG, yet it has been observed. We consider several models whereby the symmetry of the vapor is broken by the presence of the laser and compare their predictions to new observations we have made using a few-picosecond laser pulse. The two-lobed output beam profile shows that it is the vapor-plus-beam combination whose symmetry is important. The dependence on vapor pressure demonstrates the coherent nature of the radiation, while the dependence on buffer gas pressure hints at a change of the symmetry in time. The time-dependence is measured directly with a preliminary pump-probe measurement. The magnitude and intensity dependence of the signal are also measured. All but one of the models are eliminated by this comparison.

  5. Versatile thin-film reactor for photochemical vapor generation.

    PubMed

    Zheng, Chengbin; Sturgeon, Ralph E; Brophy, Christine; Hou, Xiandeng

    2010-04-01

    A novel thin-film reactor is described and evaluated for its analytical performance with photochemical vapor generation (TF-PVG). The device, comprising both the generator and a gas-liquid separator, utilizes a vertical central quartz rod onto which the sample is pumped to yield a thin liquid film conducive to the rapid escape of generated hydrophobic species. The rod is housed within a concentric quartz tube through which a flow of argon carrier/stripping gas is passed to remove and transport the generated species to a detector, which in this study is an inductively coupled argon plasma optical emission spectrometer (ICP-OES). The concentric quartz tube is itself surrounded by a 78-turn 0.5 m long quartz coil low-pressure mercury discharge lamp operating at 20 W. The performance of this thin-film photoreactor was evaluated through comparison of analytical figures of merit for detection of a number of elements undergoing PVG in the presence of formic or acetic acid with those arising from conventional solution nebulization under optimized conditions. The TF-PVG reactor provided sensitivity enhancements, of 110-, 120-, 130-, 250-, 120-, 230-, 78-, 1.3-, 16-, and 32-fold for As, Sb, Bi, Se, Te, Hg, Ni, Co, Fe, and I, respectively, and detection limit enhancements of 110-, 140-, 170-, 270-, 200-, 300-, 160-, 2.7-, 50-, and 44-fold for these same elements. Vapor generation efficiencies ranged from 20-100% for this suite of analytes. The utility of this technique was demonstrated by the determination of Fe and Ni in Certified Reference Materials DORM-3 (fish protein) and DOLT-4 (dogfish liver tissue). PMID:20225824

  6. Malaria Theranostics using Hemozoin-Generated Vapor Nanobubbles

    PubMed Central

    Hleb, Ekaterina Y. Lukianova-; Lapotko, Dmitri O.

    2014-01-01

    Malaria remains a widespread and deadly infectious human disease, with increasing diagnostic and therapeutic challenges due to the drug resistance and aggressiveness of malaria infection. Early detection and innovative approaches for parasite destruction are needed. The high optical absorbance and nano-size of hemozoin crystals have been exploited to detect and mechanically destroy the malaria parasite in a single theranostic procedure. Transient vapor nanobubbles are generated around hemozoin crystals in malaria parasites in infected erythrocytes in response to a single short laser pulse. Optical scattering signals of the nanobubble report the presence of the malaria parasite. The mechanical impact of the same nanobubble physically destroys the parasite in nanoseconds in a drug-free manner. Laser-induced nanobubble treatment of human blood in vitro results in destruction of up to 95% of parasites after a single procedure, and delivers an 8-fold better parasiticidal efficacy compared to standard chloroquine drug treatment. The mechanism of destruction is highly selective for malaria infected red cells and does not harm neighboring, uninfected erythrocytes. Thus, laser pulse-induced vapor nanobubble generation around hemozoin supports both rapid and highly specific detection and destruction of malaria parasites in one theranostic procedure. PMID:24883125

  7. INEEL portable vapor generator operations and maintenance manual

    SciTech Connect

    Gresham, G.L.; Hartenstein, S.D.; Leppert, Y.M.; Mottishaw, P.

    1997-07-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) has developed a calibrated vapor generator, which delivers reproducible vapor aliquots of a standard in the picogram to low nanogram range. The basic system design includes: (a) a reservoir that contains the target analyte, (b) a head, which contains the equipment (valves, filters, transducers) necessary to use the reservoir, and (c) a controller assembly that contains the CPU, pump, and air filtering system. The reservoir consists of a known quantity of target or analyte material (i.e., explosive, narcotic, etc.) dissolved in a solvent and deposited on an inert substrate (e.g., glass wool, stainless steel beads, etc.), which is located in a stainless steel block. The reservoir temperature is controlled via thermal electric cooler to generate a level of saturation of the target analyte in the reservoir. Each reservoir contains only a single target analyte; therefore, each analyte has its own complete head. The controller houses a small computer that performs all of the control functions. Also included in the controller are the power supplies, an air pump, a pressure regulator, air filters, flow controllers, and displays.

  8. Nonequilibrium vapor-generation model for flashing flows

    SciTech Connect

    Saha, P.; Abuaf, N.; Wu, B. J.C.

    1981-01-01

    A nonequilibrium vapor generation model for flashing flows is presented. The model consists of a flashing inception point, a bubbly flow regime followed by a bubbly-slug regime, an annular or annular-mist regime, and finally a dispersed-droplet regime. Existence of superheated liquid at the inception point and beyond is recognized. The vapor generation rate in each flow regime is calculated from the estimates for interfacial area density and net interfacial heat flux. However, the bubble number density at the flashing inception point was varied to obtain optimum fits with the void fraction data taken in a vertical converging-diverging nozzle. The interfacial area density at the inception point, thus determined, showed a rapid increase with the decrease in the liquid superheat at that point. This trend is correct since in the limit of thermal equilibrium flow where the liquid superheat approaches zero, the interfacial area for heat and mass transfer should approach infinity. 32 refs., 7 figs., 1 tab.

  9. Malaria theranostics using hemozoin-generated vapor nanobubbles.

    PubMed

    Lukianova-Hleb, Ekaterina Y; Lapotko, Dmitri O

    2014-01-01

    Malaria remains a widespread and deadly infectious human disease, with increasing diagnostic and therapeutic challenges due to the drug resistance and aggressiveness of malaria infection. Early detection and innovative approaches for parasite destruction are needed. The high optical absorbance and nano-size of hemozoin crystals have been exploited to detect and mechanically destroy the malaria parasite in a single theranostic procedure. Transient vapor nanobubbles are generated around hemozoin crystals in malaria parasites in infected erythrocytes in response to a single short laser pulse. Optical scattering signals of the nanobubble report the presence of the malaria parasite. The mechanical impact of the same nanobubble physically destroys the parasite in nanoseconds in a drug-free manner. Laser-induced nanobubble treatment of human blood in vitro results in destruction of up to 95% of parasites after a single procedure, and delivers an 8-fold better parasiticidal efficacy compared to standard chloroquine drug treatment. The mechanism of destruction is highly selective for malaria infected red cells and does not harm neighboring, uninfected erythrocytes. Thus, laser pulse-induced vapor nanobubble generation around hemozoin supports both rapid and highly specific detection and destruction of malaria parasites in one theranostic procedure. PMID:24883125

  10. Direct determination of cadmium in foods by solid sampling electrothermal vaporization inductively coupled plasma mass spectrometry using a tungsten coil trap

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Mao, Xuefei; Liu, Jixin; Wang, Min; Qian, Yongzhong; Gao, Chengling; Qi, Yuehan

    2016-04-01

    In this work, a solid sampling device consisting of a tungsten coil trap, porous carbon vaporizer and on-line ashing furnace of a Ni-Cr coil was interfaced with inductively coupled plasma mass spectrometry (ICP-MS). A modified double gas circuit system was employed that was composed of carrier and supplemental gas lines controlled by separate gas mass flow controllers. For Cd determination in food samples using the assembled solid sampling ICP-MS, the optimal ashing and vaporization conditions, flow rate of the argon-hydrogen (Ar/H2) (v:v = 24:1) carrier gas and supplemental gas, and minimum sampling mass were investigated. Under the optimized conditions, the limit of quantification was 0.5 pg and the relative standard deviation was within a 10.0% error range (n = 10). Furthermore, the mean spiked recoveries for various food samples were 99.4%-105.9% (n = 6). The Cd concentrations measured by the proposed method were all within the certified values of the reference materials or were not significantly different (P > 0.05) from those of the microwave digestion ICP-MS method, demonstrating the good accuracy and precision of the solid sampling ICP-MS method for Cd determination in food samples.

  11. A novel capillary microextraction on ordered mesoporous titania coating combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of V, Cr and Cu in environmental and biological samples.

    PubMed

    Wu, Yiwei; Hu, Bin; Hu, Wenling; Jiang, Zucheng; Li, Boyangzi

    2007-04-01

    In this work, an ordered mesoporous titania film was introduced to coat a capillary by means of sol-gel technique. Sol-gel titania coating was developed for the preconcentration/separation of trace V, Cr and Cu by capillary microextraction (CME), and the adsorbed analytes were eluted for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) detection. By immobilizing sol-gel titania on the inner surface of a fused-silica microextraction capillary, the sol-gel titania coating was prepared easily. Its adsorption properties, stability and the factors affecting the adsorption behaviors of V, Cr and Cu were investigated in detail. At pH range of 7 to 9, the titania-coated capillary (50 cm x 0.25 mm) is selective towards V, Cr and Cu, and the target analytes could be desorbed quantitatively with 50 microl of 1.0 mol l(-1) HNO3 at the rate of 0.05 ml min(-1). With a consumption of 2 ml sample solution, an enrichment factor of 33.3, and a detection limit (3 s) of 1.1 pg ml(-1) (10.5 fg) for V; 3.3 pg ml(-1) (33.0 fg) for Cr and 6.3 pg ml(-1) (63.1 fg) for Cu respectively were obtained. The precisions Relative Standard Deviations (RSDs) for nine replicate measurements of 1 ng ml(-1) V, Cr and Cu were 3.4, 5.1 and 6.4%, respectively. The proposed method has been applied to the determination of V, Cr and Cu in human urine and lake water, and the recoveries for these elements were 89.2 approximately 105%. The developed method was also applied to the determination of the target elements in NIES No. 10-a (rice flour-unpolished) and NIES No. 9 (sargasso) certified reference materials, and the results found are in good agreement with the certified values. PMID:17256811

  12. Electrothermal oscillations and the quasilinear theory of electron enthalpy fluctuations in magnetohydrodynamic generators and magnetoplasmadynamic arc thrusters

    NASA Technical Reports Server (NTRS)

    Smith, J. M.

    1972-01-01

    Flucturations in electron density and temperature coupled through OHM's Law are studied for MHD power generator and MPD arc thruster applications. The dispersion relation based on linear theory is derived, and the two limiting cases of infinite ionization rate and frozen flow are examined. The nonlinear effects of the frozen flow case are then studied in the quasilinear limit. Equations are derived for the amplitude of the fluctuation and its effect upon Ohm's Law and the electron temperature equation. Conditions under which a steady state can exist in the presence of the fluctuation are examined, and effective transport properties are determined.

  13. Mixed metal vapor phase matching for third-harmonic generation

    NASA Technical Reports Server (NTRS)

    Bloom, D. M.; Young, J. F.; Harris, S. E.

    1975-01-01

    Phase matching for frequency tripling of 1.06 microns is demonstrated in a homogeneous mixture of sodium and magnesium vapor. The ratio of Mg to Na vapor pressures required for phase matching is 2:1. This ratio is about 1/75 of that required to phase match Na with Xe.

  14. Simulation studies of vapor bubble generation by short-pulse lasers

    SciTech Connect

    Amendt, P.; London, R.A.; Strauss, M.

    1997-10-26

    Formation of vapor bubbles is characteristic of many applications of short-pulse lasers in medicine. An understanding of the dynamics of vapor bubble generation is useful for developing and optimizing laser-based medical therapies. To this end, experiments in vapor bubble generation with laser light deposited in an aqueous dye solution near a fiber-optic tip have been performed. Numerical hydrodynamic simulations have been developed to understand and extrapolate results from these experiments. Comparison of two-dimensional simulations with the experiment shows excellent agreement in tracking the bubble evolution. Another regime of vapor bubble generation is short-pulse laser interactions with melanosomes. Strong shock generation and vapor bubble generation are common physical features of this interaction. A novel effect of discrete absorption by melanin granules within a melanosome is studied as a possible role in previously reported high Mach number shocks.

  15. Electrothermal pumping with interdigitated electrodes and resistive heaters.

    PubMed

    Williams, Stuart J; Green, Nicolas G

    2015-08-01

    Interdigitated electrodes are used in electrokinetic lab-on-a-chip devices for dielectrophoretic trapping and characterization of suspended particles, as well as the production of field-induced fluid flow via AC electroosomosis and electrothermal mechanisms. However, the optimum design for dielectrophoresis, that if symmetrical electrodes, cannot induce bulk electrohydrodynamic pumping. In addition, the mechanism of intrinsic electrothermal pumping is affected by the properties of the fluid, with thermal fields being generated by Joule Heating. This work demonstrates the incorporation of an underlying thin film heater, electrically isolated from the interdigitated electrodes by an insulator layer, to enhance bulk electrothermal pumping. The use of integrated heaters allows the thermal field generation to be controlled independently of the electric field. Numerical simulations are performed to demonstrate the importance of geometrical arrangement of the heater with respect to the interdigitated electrodes, as well as electrode size, spacing, and arrangement. The optimization of such a system is a careful balance between electrokinetics, heat transfer, and fluid dynamics. The heater location and electrode spacing influence the rate of electrothermal pumping significantly more than electrode width and insulator layer thickness. This demonstration will aid in the development of microfluidic electrokinetic systems that want to utilize the advantages associated with electrothermal pumping while simultaneously applying other lab-on-a-chip electrokinetics like dielectrophoresis. PMID:26010255

  16. Systems and methods for generation of hydrogen peroxide vapor

    DOEpatents

    Love, Adam H; Eckels, Joel Del; Vu, Alexander K; Alcaraz, Armando; Reynolds, John G

    2014-12-02

    A system according to one embodiment includes a moisture trap for drying air; at least one of a first container and a second container; and a mechanism for at least one of: bubbling dried air from the moisture trap through a hydrogen peroxide solution in the first container for producing a hydrogen peroxide vapor, and passing dried air from the moisture trap into a headspace above a hydrogen peroxide solution in the second container for producing a hydrogen peroxide vapor. A method according one embodiment includes at least one of bubbling dried air through a hydrogen peroxide solution in a container for producing a first hydrogen peroxide vapor, and passing dried air from the moisture trap into a headspace above the hydrogen peroxide solution in a container for producing a second hydrogen peroxide vapor. Additional systems and methods are also presented.

  17. Electromagnetic Properties of Impact-Generated Plasma, Vapor and Debris

    SciTech Connect

    Crawford, D.A.; Schultz, P.H.

    1998-11-02

    Plasma, vapor and debris associated with an impact or explosive event have been demonstrated in the laboratory to produce radiofrequency and optical electromagnetic emissions that can be diagnostic of the event. Such effects could potentially interfere with communications or remote sensing equipment if an impact occurred, for example, on a satellite. More seriously, impact generated plasma could end the life of a satellite by mechanisms that are not well understood and not normally taken into account in satellite design. For example, arc/discharge phenomena resulting from highly conductive plasma acting as a current path across normally shielded circuits may have contributed to the loss of the Olympus experimental communications satellite on August 11, 1993. The possibility of significant storm activity during the Leonid meteor showers of November 1998, 1999 and 2000 (impact velocity, 72 km/s) has heightened awareness of potential vulnerabilities from hypervelocity electromagnetic effects to orbital assets. The concern is justified. The amount of plasma, electrostatic charge and the magnitude of the resulting currents and electric fields scale nearly as the cube of the impact velocity. Even for microscopic Leonid impacts, the amount of plasma approaches levels that could be dangerous to spacecraft electronics. The degree of charge separation that occurs during hypervelocity impacts scales linearly with impactor mass. The resulting magnetic fields increase linearly with impactor radius and could play a significant role in our understanding of the paleomagnetism of planetary surfaces. The electromagnetic properties of plasma produced by hypervelocity impact have been exploited by researchers as a diagnostic tool, invoked to potentially explain the magnetically jumbled state of the lunar surface and blamed for the loss of the Olympus experimental communications satellite. The production of plasma in and around an impact event can lead to several effects: (1) the

  18. Vaporization and compatibility of SiGe radioisotope thermoelectric generators.

    NASA Technical Reports Server (NTRS)

    Staley, H. G.; Rovner, L. H.; Snowden, D.; Elsner, N. B.

    1972-01-01

    The limiting operating temperatures of SiGe thermoelectrics designed for extended operation are set by sublimation process of the elements and by considerations of their compatibility with the surrounding insulating elements. Mass spectrometric Knudsen cell and Langmuir vaporization modes of operation have been utilized in the study of the equilibrium vapor species and in the time evaluation of the sublimation process. Isothermal high-vacuum (1 ntorr) anneals of samples have extended observations to long-time spans. The time variations follow the formation of surface depletion layers due to disproportional rates of sublimation of the various species.

  19. Continuous generation of rubidium vapor in hollow-core photonic bandgap fibers.

    PubMed

    Donvalkar, Prathamesh S; Ramelow, Sven; Clemmen, Stéphane; Gaeta, Alexander L

    2015-11-15

    We demonstrate high optical depths (50±5) that last for hours in rubidium-filled hollow-core photonic bandgap fibers, which represent a 1000× improvement over the operation times previously reported. We investigate the vapor generation mechanism using both a continuous wave and a pulsed light source, and find that the mechanism for generating the rubidium atoms is primarily due to thermal vaporization. The continuous generation of large vapor densities should enable measurements at the single-photon level by averaging over longer time scales. PMID:26565879

  20. Vapor bubble generation around gold nano-particles and its application to damaging of cells.

    PubMed

    Kitz, M; Preisser, S; Wetterwald, A; Jaeger, M; Thalmann, G N; Frenz, M

    2011-01-01

    We investigated vapor bubbles generated upon irradiation of gold nanoparticles with nanosecond laser pulses. Bubble formation was studied both with optical and acoustic means on supported single gold nanoparticles and single nanoparticles in suspension. Formation thresholds determined at different wavelengths indicate a bubble formation efficiency increasing with the irradiation wavelength. Vapor bubble generation in Bac-1 cells containing accumulations of the same particles was also investigated at different wavelengths. Similarly, they showed an increasing cell damage efficiency for longer wavelengths. Vapor bubbles generated by single laser pulses were about half the cell size when inducing acute damage. PMID:21339875

  1. 46 CFR 52.25-10 - Organic fluid vaporizer generators (modifies PVG-1 through PVG-12).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... reference; see 46 CFR 52.01-1) except as noted otherwise in this section. (b) The application and end use of... 46 Shipping 2 2012-10-01 2012-10-01 false Organic fluid vaporizer generators (modifies PVG-1... (CONTINUED) MARINE ENGINEERING POWER BOILERS Other Boiler Types § 52.25-10 Organic fluid vaporizer...

  2. 46 CFR 52.25-10 - Organic fluid vaporizer generators (modifies PVG-1 through PVG-12).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... reference; see 46 CFR 52.01-1) except as noted otherwise in this section. (b) The application and end use of... 46 Shipping 2 2011-10-01 2011-10-01 false Organic fluid vaporizer generators (modifies PVG-1... (CONTINUED) MARINE ENGINEERING POWER BOILERS Other Boiler Types § 52.25-10 Organic fluid vaporizer...

  3. 46 CFR 52.25-10 - Organic fluid vaporizer generators (modifies PVG-1 through PVG-12).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... reference; see 46 CFR 52.01-1) except as noted otherwise in this section. (b) The application and end use of... 46 Shipping 2 2013-10-01 2013-10-01 false Organic fluid vaporizer generators (modifies PVG-1... (CONTINUED) MARINE ENGINEERING POWER BOILERS Other Boiler Types § 52.25-10 Organic fluid vaporizer...

  4. 46 CFR 52.25-10 - Organic fluid vaporizer generators (modifies PVG-1 through PVG-12).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... reference; see 46 CFR 52.01-1) except as noted otherwise in this section. (b) The application and end use of... 46 Shipping 2 2010-10-01 2010-10-01 false Organic fluid vaporizer generators (modifies PVG-1... (CONTINUED) MARINE ENGINEERING POWER BOILERS Other Boiler Types § 52.25-10 Organic fluid vaporizer...

  5. 46 CFR 52.25-10 - Organic fluid vaporizer generators (modifies PVG-1 through PVG-12).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... reference; see 46 CFR 52.01-1) except as noted otherwise in this section. (b) The application and end use of... 46 Shipping 2 2014-10-01 2014-10-01 false Organic fluid vaporizer generators (modifies PVG-1... (CONTINUED) MARINE ENGINEERING POWER BOILERS Other Boiler Types § 52.25-10 Organic fluid vaporizer...

  6. Bibliography of electrothermal thruster technology, 1984

    SciTech Connect

    Sovey, J.S.; Hardy, T.L.; Englehart, M.

    1986-03-01

    Electrothermal propulsion concepts are briefly discussed as an introduction to a bibliography and author index. Nearly 700 citations are given for resistojets, thermal arcjets, pulsed electrothermal thrusters, microwave heated devices, solar thermal thrusters, and laser thermal thrusters.

  7. A bibliography of electrothermal thruster technology, 1984

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.; Hardy, T. L.; Englehart, M.

    1986-01-01

    Electrothermal propulsion concepts are briefly discussed as an introduction to a bibliography and author index. Nearly 700 citations are given for resistojets, thermal arcjets, pulsed electrothermal thrusters, microwave heated devices, solar thermal thrusters, and laser thermal thrusters.

  8. A comprehensive, numerical model of electro-thermal propulsion

    NASA Astrophysics Data System (ADS)

    Silvestre, N.; Hensel, D.; Daree, K.

    1993-01-01

    A computer model of an electrothermal accelerator has been developed which applies to the plasma generator as well as the gun barrel, and it for the first time allows study of the interdependent physical processes in both components simultaneously. The code comprises a 2D transient description of the plasma arc, a 2D, two-phase interior ballistics module, and a preprocessor delivering the required plasma physical data. Some results on the flow field, pressure and temperature in a typical accelerator are presented, and probable limitations on the performance of such a system are discussed. The code is to be applied to different concepts of electrothermal chemical guns.

  9. Trace Explosives Vapor Generation and Quantitation at Parts per Quadrillion Concentrations.

    PubMed

    Giordano, Braden C; Field, Christopher R; Andrews, Benjamin; Lubrano, Adam; Woytowitz, Morgan; Rogers, Duane; Collins, Greg E

    2016-04-01

    The generation of trace 2,4,6-trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), and pentaerythritol tetranitrate (PETN) vapors using a pneumatically modulated liquid delivery system (PMLDS) coupled to a polytetrafluoroethylene (PTFE) total-consumption micronebulizer is presented. The vapor generator operates in a continuous manner with final vapor concentrations proportional to the explosive concentration in aqueous solution delivered through the nebulizer and the diluent air flow rate. For quantitation of concentrations in the parts per billionvolume (ppbv) to parts per trillionvolume (pptrv) range, Tenax-TA thermal desorption tubes were used for vapor collection with subsequent analysis on a thermal-desorption system programmable-temperature vaporization gas chromatograph (TDS-PTV-GC) with a μ-ECD detector. With 30 min sample times and an average sampling rate of 100 mL min(-1), vapor concentrations of 38 pptrv for TNT, 25 pptrv for RDX, and 26 pptrv for PETN were determined. For parts per quadrillionvolume (ppqv) vapor quantitation of TNT and RDX, an online PTV-GC system with a negative-ion chemical ionization mass spectrometer (methane reagent gas) was used for direct sampling and capture of the vapor on the PTV inlet. Vapor concentrations as low as 160 ppqv and 710 ppqv for TNT and RDX were quantified, respectively, with an instrument duty cycle as low as 4 min. PMID:26971624

  10. Electrothermal Analysis of Lithium Ion Batteries

    SciTech Connect

    Pesaran, A.; Vlahinos, A.; Bharathan, D.; Duong, T.

    2006-03-01

    This report presents the electrothermal analysis and testing of lithium ion battery performance. The objectives of this report are to: (1) develop an electrothermal process/model for predicting thermal performance of real battery cells and modules; and (2) use the electrothermal model to evaluate various designs to improve battery thermal performance.

  11. Multiply stripped ion generation in the metal vapor vacuum arc

    SciTech Connect

    Brown, I.G.; Feinberg, B.; Galvin, J.E.

    1986-08-01

    We consider the charge state distribution of ions produced in the metal vapor vacuum arc plasma discharge. A high current metal ion source, the MEVVA ion source, in which the ion beam is extracted from a metal vapor vacuum arc plasma, has been used to obtain the spectra of multiple charged ions produced within the cathode spots. A computer calculation of the charge state distribution that evolves within the spots via stepwide ionization of ions by electron impact provides a theoretical basis for comparison of the data. In this paper we report on the measured charge state distributions for a wide variety of metallic species and compare these results with the predictions of this theory. 55 refs.

  12. Mitigation of Electrothermal Instabilities with Thick Insulating Coatings

    NASA Astrophysics Data System (ADS)

    Peterson, Kyle; Awe, Thomas; Yu, Edmund; Sinars, Daniel; Cuneo, Michael

    2013-10-01

    We will show results of recent experiments on Sandia's Z facility that demonstrate a dramatic reduction in instability growth when thick insulating coatings are used to mitigate electrothermal instability growth in magnetically driven imploding liners. These results also provide further evidence that the inherent surface roughness as a result of target fabrication is not the dominant seed for the growth of Magneto-Rayleigh-Taylor (MRT) instabilities in liners with carefully machined smooth surfaces (~100 nm surface RMS or better), but rather electrothermal instabilities that form early in the electrical current pulse as Joule heating melts and vaporizes the liner surface. More importantly, these results suggest a mechanism for possibly reducing the integral MRT instability growth substantially in magnetically driven inertial confinement fusion concepts such as MagLIF. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. Heat exchanger for electrothermal devices

    NASA Technical Reports Server (NTRS)

    Zavesky, Ralph J. (Inventor); Sovey, James S. (Inventor); Mirtich, Michael J. (Inventor); Marinos, Charalampus (Inventor); Penko, Paul F. (Inventor)

    1986-01-01

    An improved electrothermal device is disclosed. An electrothermal thruster utilizes a generally cylindrical heat exchanger chamber to convert electricity to heat which raises the propellant temperature. A textured, high emissivity heat element radiatively transfers heat to the inner wall of this chamber that is ion beam morphologically controlled for high absorptivity. This, in turn, raises the temperature of a porous heat exchanger material in an annular chamber surrounding the cylindrical chamber. Propellant gas flows through the annular chamber and is heated by the heat exchanger material.

  14. Generation of Shock-Wave Disturbances at Plasma-Vapor Bubble Oscillation

    NASA Astrophysics Data System (ADS)

    Kuznetsova, N. S.; Yudin, A. S.; Voitenko, N. V.

    2015-11-01

    The complex physical and mathematical model describing all steps of plasma-vapor bubble evolution in the system of the water-ground condensed media is presented. Discharge circuit operation, discharge plasma channel expansion, its transformation into the vapor-plasma bubble and its pulsation, pressure wave generation and propagation of the mechanical stress waves in the ground are self-consistently considered in the model. The model allows investigation of the basic laws of stored energy transformation into the discharge plasma channel, next to the plasma-vapor bubble and transformation of this energy to the energy of pressure wave compressing the surrounding ground. Power characteristics of wave disturbances generated by gas-vapor bubble oscillation in liquid depending on the circuit parameters are analyzed for the prediction of the ground boundary displacement. The dynamics of the shock-wave propagation in water-ground condensed media depending on the rate of the plasma channel energy release is investigated. Simulation of the shock-wave phenomena at a plasma-vapor bubble oscillation in condensed media consecutively describes the physical processes underlying technology for producing piles by electro-discharge stuffing. The quantitative model verified by physical experimental tests will allow optimization of pulse generator parameters and electrode system construction of high-voltage equipment.

  15. Generation and evolution of impact-induced vapor clouds: Spectroscopic observations and hydrodynamic calculations

    NASA Astrophysics Data System (ADS)

    Sugita, Seiji

    1999-11-01

    Generation of vapor is a natural consequence of hypervelocity collisions between major planets and small bodies in the Solar System. Resulting impact vapor clouds may induce a variety of processes on the surface of a planet. One of the key factors in impact-induced vaporization is energy partitioning. Conventional wisdom teaches that the energy partitioned during an impact is predicted completely by the Rankine-Hugoniot equations and equations of states. Consequently, extensive efforts have been made both to develop mathematical/numerical methods to solve these equations accurately and to determine material-dependent constants using 1- dimensional impact experiments (i.e., flyer-plate experiments). Recent laboratory experiments, however, revealed that 3- dimensional hypervelocity impacts show intriguing processes that highly sophisticated hydrocodes do not readily account for, such as enhanced vaporization at low impact angles (measured from the horizontal) and impactor survival. Radar mapping of Venus by the Magellan spacecraft also revealed that craters on Venus have features consistent with processes observed in laboratory experiments. In particular, morphological observations indicate that run-out flows around Venus craters may be contributed largely by condensates from the downrange component of impact vapor clouds observed in laboratory experiments. Based on these new findings, the work presented in this thesis attempts to understand energy partitioning mechanisms during both generation and subsequent evolution of impact vapor clouds. To achieve this goal, I took two approaches. First, I looked at run-out flows around impact craters on Venus to extract information on impact-induced vapor clouds at planetary scales. In order to decipher this geologic record, I carried out numerical calculations of the interactions between an atmosphere and vapor clouds induced by oblique impacts. The second approach is to go back to a laboratory to understand the basic physics

  16. Determination of cadmium in water samples by fast pyrolysis-chemical vapor generation atomic fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Jingya; Fang, Jinliang; Duan, Xuchuan

    2016-08-01

    A pyrolysis-vapor generation procedure to determine cadmium by atomic fluorescence spectrometry has been established. Under fast pyrolysis, cadmium ion can be reduced to volatile cadmium species by sodium formate. The presence of thiourea enhanced the efficiency of cadmium vapor generation and eliminated the interference of copper. The possible mechanism of vapor generation of cadmium was discussed. The optimization of the parameters for pyrolysis-chemical vapor generation, including pyrolysis temperature, amount of sodium formate, concentration of hydrochloric acid, and carrier argon flow rate were carried out. Under the optimized conditions, the absolute and concentration detection limits were 0.38 ng and 2.2 ng ml- 1, respectively, assuming that 0.17 ml of sample was injected. The generation efficiency of was 28-37%. The method was successfully applied to determine trace amounts of cadmium in two certified reference materials of Environmental Water (GSB07-1185-2000 and GSBZ 50009-88). The results were in good agreement with the certified reference values.

  17. NASA electrothermal auxiliary propulsion technology

    NASA Technical Reports Server (NTRS)

    Stone, J. R.

    1986-01-01

    Electrothermal auxiliary propulsion systems provide high performance options which can have major mission benefits. There are several electrothermal concepts which offer a range of characteristics and benefits. Resistojets are the highest thrust to power option and are currently operational at mission average values of specific impulse, I sub sp approximately 295 sec. Long life, multipropellant resistojets are being developed for the space station, and resistojet technology advancements are being pursued to improve the I sub sp by more than 20 percent for resistojets used in satellite applications. Direct current arcjets have the potential of I sub sp over 400 sec with storable propellants and should provide over 1000 sec with hydrogen. Advanced concepts are being investigated to provide high power density options and possible growth to primary propulsion applications. Broad based experimental and analytical research and technology programs of NASA are summarized and recent significant advances are reviewed.

  18. Testing and Results of Human Metabolic Simulation Utilizing Ultrasonic Nebulizer Technology for Water Vapor Generation

    NASA Technical Reports Server (NTRS)

    Stubbe, Matthew; Curley, Su

    2010-01-01

    Life support technology must be evaluated thoroughly before ever being implemented into a functioning design. A major concern during that evaluation is safety. The ability to mimic human metabolic loads allows test engineers to evaluate the effectiveness of new technologies without risking injury to any actual humans. The main function of most life support technologies is the removal of carbon dioxide (CO2) and water (H2O) vapor. As such any good human metabolic simulator (HMS) will mimic the human body s ability to produce these items. Introducing CO2 into a test chamber is a very straightforward process with few unknowns so the focus of this particular new HMS design was on the much more complicated process of introducing known quantities of H2O vapor on command. Past iterations of the HMS have utilized steam which is very hard to keep in vapor phase while transporting and injecting into a test chamber. Also steam adds large quantities of heat to any test chamber, well beyond what an actual human does. For the new HMS an alternative approach to water vapor generation was designed utilizing ultrasonic nebulizers as a method for creating water vapor. Ultrasonic technology allows water to be vibrated into extremely tiny pieces (2-5 microns) and evaporate without requiring additional heating. Doing this process inside the test chamber itself allows H2O vapor generation without the unwanted heat and the challenging process of transporting water vapor. This paper presents the design details as well as results of all initial and final acceptance system testing. Testing of the system was performed at a range of known human metabolic rates in both sea-level and reduced pressure environments. This multitude of test points fully defines the systems capabilities as they relate to actual environmental systems testing.

  19. Advancements in oxygen generation and humidity control by water vapor electrolysis

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Sudar, M.; Lee, M. C.

    1988-01-01

    Regenerative processes for the revitalization of manned spacecraft atmospheres or other manned habitats are essential for realization of long-term space missions. These processes include oxygen generation through water electrolysis. One promising technique of water electrolysis is the direct conversion of the water vapor contained in the cabin air to oxygen. This technique is the subject of the present program on water vapor electrolysis development. The objectives were to incorporate technology improvements developed under other similar electrochemical programs and add new ones; design and fabricate a mutli-cell electrochemical module and a testing facility; and demonstrate through testing the improvements. Each aspect of the water vapor electrolysis cell was reviewed. The materials of construction and sizing of each element were investigated analytically and sometime experimentally. In addition, operational considerations such as temperature control in response to inlet conditions were investigated. Three specific quantitative goals were established.

  20. Collimated Blue and Infrared Beams Generated by Two-Photon Excitation in Rubidium Vapor

    NASA Astrophysics Data System (ADS)

    Gearba, Alina; Sell, Jerry; Olesen, Robert; Knize, Randy

    2016-05-01

    Utilizing nonlinear optical processes in Rb vapor we describe the generation of optical fields at 420 nm, 1.32 μm, and 1.37 μm. Input laser beams at 780 nm and 776 nm enter a heated Rb vapor cell collinear and circularly polarized. Rubidium atoms are excited to the 5D5 / 2 state, with blue light generated by four-wave mixing through the 6P3 / 2 --> 5S1 / 2 states, while infrared beams at 1.37 μm and 1.32 μm are generated by cascading decays through the 6S1 / 2 --> 5P3 / 2 and 6S1 / 2 --> 5P1 / 2 states, respectively. While the blue beam emission from four-wave mixing has been studied in detail, the mechanisms responsible for generating the infrared beams are still under investigation. We will present our results for the conditions which give rise to infrared beam generation by two-photon excitation in rubidium vapor.

  1. Investigation of a repetitive pulsed electrothermal thruster

    NASA Technical Reports Server (NTRS)

    Burton, R. L.; Fleischer, D.; Goldstein, S. A.; Tidman, D. A.; Winsor, N. K.

    1986-01-01

    A pulsed electrothermal (PET) thruster with 1000:1 ratio nozzle is tested in a repetitive mode on water propellant. The thruster is driven by a 60J pulse forming network at repetition rates up to 10 Hz (600W). The pulse forming network has a .31 ohm impedance, well matched to the capillary discharge resistance of .40 ohm, and is directly coupled to the thruster electrodes without a switch. The discharge is initiated by high voltage breakdown, typically at 2500V, through the water vapor in the interelectrode gap. Water is injected as a jet through a .37 mm orifice on the thruster axis. Thruster voltage, current and impulse bit are recorded for several seconds at various power supply currents. Thruster to power ratio is typically T/P = .07 N/kW. Tank background pressure precludes direct measurement of exhaust velocity which is inferred from calculated pressure and temperature in the discharge to be about 14 km/sec. Efficiency, based on this velocity and measured T/P is .54 + or - .07. Thruster ablation is zero at the throat and becomes measurable further upstream, indicating that radiative ablation is occurring late in the pulse.

  2. Health assessment of gasoline and fuel oxygenate vapors: generation and characterization of test materials.

    PubMed

    Henley, Michael; Letinski, Daniel J; Carr, John; Caro, Mario L; Daughtrey, Wayne; White, Russell

    2014-11-01

    In compliance with the Clean Air Act regulations for fuel and fuel additive registration, the petroleum industry, additive manufacturers, and oxygenate manufacturers have conducted comparative toxicology testing on evaporative emissions of gasoline alone and gasoline containing fuel oxygenates. To mimic real world exposures, a generation method was developed that produced test material similar in composition to the re-fueling vapor from an automotive fuel tank at near maximum in-use temperatures. Gasoline vapor was generated by a single-step distillation from a 1000-gallon glass-lined kettle wherein approximately 15-23% of the starting material was slowly vaporized, separated, condensed and recovered as test article. This fraction was termed vapor condensate (VC) and was prepared for each of the seven test materials, namely: baseline gasoline alone (BGVC), or gasoline plus an ether (G/MTBE, G/ETBE, G/TAME, or G/DIPE), or gasoline plus an alcohol (G/EtOH or G/TBA). The VC test articles were used for the inhalation toxicology studies described in the accompanying series of papers in this journal. These studies included evaluations of subchronic toxicity, neurotoxicity, immunotoxicity, genotoxicity, reproductive and developmental toxicity. Results of these studies will be used for comparative risk assessments of gasoline and gasoline/oxygenate blends by the US Environmental Protection Agency. PMID:24852493

  3. Permanent modification in electrothermal atomic absorption spectrometry — advances, anticipations and reality

    NASA Astrophysics Data System (ADS)

    Tsalev, Dimiter L.; Slaveykova, Vera I.; Lampugnani, Leonardo; D'Ulivo, Alessandro; Georgieva, Rositsa

    2000-05-01

    Permanent modification is an important recent development in chemical modification techniques which is promising in view of increasing sample throughput with 'fast' programs, reducing reagent blanks, preliminary elimination of unwanted modifier components, compatibility with on-line and in situ enrichment, etc. An overview of this approach based on the authors' recent research and scarce literature data is given, revealing both success and failure in studies with permanently modified surfaces (carbides, non-volatile noble metals, noble metals on carbide coatings, etc.), as demonstrated in examples of direct electrothermal atomic absorption spectrometric (ETAAS) applications to biological and environmental matrices and vapor generation (VG)-ETAAS coupling with in-atomizer trapping of hydrides and other analyte vapors. Permanent modifiers exhibit certain drawbacks and limitations such as: poorly reproducible treatment technologies — eventually resulting in poor tube-to-tube repeatability and double or multiple peaks; impaired efficiency compared with modifier addition to each sample aliquot; relatively short lifetimes; limitations imposed on temperature programs, the pyrolysis, atomization and cleaning temperatures being set somewhat lower to avoid excessive loss of modifier; applicability to relatively simple sample solutions rather than to high-salt matrices and acidic digests; side effects of overstabilization, etc. The most important niches of application appear to be the utilization of permanently modified surfaces in coupled VG-ETAAS techniques, analysis of organic solvents and extracts, concentrates and fractions obtained after enrichment and/or speciation separations and direct ETAAS determinations of highly volatile analytes in relatively simple sample matrices.

  4. Second harmonic generation in ZnO thin films fabricated by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Liu, C. Y.; Zhang, B. P.; Binh, N. T.; Segawa, Y.

    2004-07-01

    Second harmonic generation (SHG) from ZnO thin films fabricated by metalorganic chemical vapor deposition (MOCVD) technique was carried out. By comparing the second harmonic signal generated in a series of ZnO films with different deposition temperatures, we conclude that a significant part of second harmonic signal is generated at the film deposited with appropriate temperature. The second-order susceptibility tensor χ(2)zzz=9.2 pm/V was deduced for a film deposited at 250 °C.

  5. [The measurement of water vapor isotope based on mid-infrared difference frequency generation].

    PubMed

    Wang, Zhu-Qing; Wang, Huan P; Cao, Zhen-Song; Yuan, Yi-Qian; Zhang, Wei-Jun; Gong, Zhi-Ben; Gao, Xiao-Ming

    2009-12-01

    Stable-isotope ratio analysis of water is an important tool for geology, meteorology, and earth sciences. Measurements of water vapor isotopes are very helpful to explaining stratospheric aridity and related issues in atmospheric sciences. The absorption of water vapor near 2.7 microm is very strong so it is suitable for measuring high sensitivity spectra. Based on difference frequency generation and quasi-phase matching, by mixing an Nd : YAG laser with Ti : Sapphire tunable from 750 to 840 nm in a 50 mm long periodically poled lithium niobate (PPLN) crystal, a widely tunable CW laser source was generated for the mid-infrared spectral range from 2.5 to 4 microm. We chose lambda = 20 microm for PPLN crystal, the generated laser was around 2.7 microm. This laser is widely tunable and of inherent narrow linewidth based on difference-frequency generation. Using this idler laser and 100 m multi-pass cell, and direct absorption the water vapor isotopes were measured in the laboratory air. The authors measured isotopes ratios and delta17O, delta18O and deltaD. The values were found to be in excellent agreement with the standard value for three individual lines. PMID:20210148

  6. Design and calibration of pulsed vapor generators for TNT, RDX and PETN

    SciTech Connect

    Davies, J.P.; Blackwood, L.G.; Davis, S.G.; Goodrich, L.D.; Larson, R.A.

    1992-12-31

    Computer controlled explosive vapor generators for 2,4,6trinitrotoluene (TNT), cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) and pentaerythritol tetranitrate (PETN) were built and calibrated to support an Independent Validation and Verification (IV&V) facility for Explosive Detection Systems (EDS) for the Federal Aviation Administration (FAA) at the Idaho National Engineering Laboratory. The generators were constructed using pure explosive suspended on quartz beads which were then loaded into a stainless steel tube. The tube was coiled and placed into a temperature controlled chamber. A carrier gas (ultra-pure air) was passed through the coil to carry the explosive molecules. The generators are capable of delivering a pulse of varying explosive mass through the control of coil temperature, air flow rate, and pulse width. Preliminary calibrations have been completed in the picogram to nanogram range using an Ion Mobility Spectrometer (IMS) as the calibrating instrument. The explosive vapor generators will be used as quantitative vapor standards to establish the lower limit of detection for EDS systems at the IV&V.

  7. CHEMISTRY OF IMPACT-GENERATED SILICATE MELT-VAPOR DEBRIS DISKS

    SciTech Connect

    Visscher, Channon; Fegley, Bruce Jr.

    2013-04-10

    In the giant impact theory for lunar origin, the Moon forms from material ejected by the impact into an Earth-orbiting disk. Here we report the initial results from a silicate melt-vapor equilibrium chemistry model for such impact-generated planetary debris disks. In order to simulate the chemical behavior of a two-phase (melt+vapor) disk, we calculate the temperature-dependent pressure and chemical composition of vapor in equilibrium with molten silicate from 2000 to 4000 K. We consider the elements O, Na, K, Fe, Si, Mg, Ca, Al, Ti, and Zn for a range of bulk silicate compositions (Earth, Moon, Mars, eucrite parent body, angrites, and ureilites). In general, the disk atmosphere is dominated by Na, Zn, and O{sub 2} at lower temperatures (<3000 K) and SiO, O{sub 2}, and O at higher temperatures. The high-temperature chemistry is consistent for any silicate melt composition, and we thus expect abundant SiO, O{sub 2}, and O to be a common feature of hot, impact-generated debris disks. In addition, the saturated silicate vapor is highly oxidizing, with oxygen fugacity (f{sub O{sub 2}}) values (and hence H{sub 2}O/H{sub 2} and CO{sub 2}/CO ratios) several orders of magnitude higher than those in a solar-composition gas. High f{sub O{sub 2}} values in the disk atmosphere are found for any silicate composition because oxygen is the most abundant element in rock. We thus expect high oxygen fugacity to be a ubiquitous feature of any silicate melt-vapor disk produced via collisions between rocky planets.

  8. Chemistry of Impact-generated Silicate Melt-vapor Debris Disks

    NASA Astrophysics Data System (ADS)

    Visscher, Channon; Fegley, Bruce, Jr.

    2013-04-01

    In the giant impact theory for lunar origin, the Moon forms from material ejected by the impact into an Earth-orbiting disk. Here we report the initial results from a silicate melt-vapor equilibrium chemistry model for such impact-generated planetary debris disks. In order to simulate the chemical behavior of a two-phase (melt+vapor) disk, we calculate the temperature-dependent pressure and chemical composition of vapor in equilibrium with molten silicate from 2000 to 4000 K. We consider the elements O, Na, K, Fe, Si, Mg, Ca, Al, Ti, and Zn for a range of bulk silicate compositions (Earth, Moon, Mars, eucrite parent body, angrites, and ureilites). In general, the disk atmosphere is dominated by Na, Zn, and O2 at lower temperatures (<3000 K) and SiO, O2, and O at higher temperatures. The high-temperature chemistry is consistent for any silicate melt composition, and we thus expect abundant SiO, O2, and O to be a common feature of hot, impact-generated debris disks. In addition, the saturated silicate vapor is highly oxidizing, with oxygen fugacity (f_O_2) values (and hence H2O/H2 and CO2/CO ratios) several orders of magnitude higher than those in a solar-composition gas. High f_O_2 values in the disk atmosphere are found for any silicate composition because oxygen is the most abundant element in rock. We thus expect high oxygen fugacity to be a ubiquitous feature of any silicate melt-vapor disk produced via collisions between rocky planets.

  9. Evolution of light-induced vapor generation at a liquid-immersed metallic nanoparticle

    PubMed Central

    Zhen, Yu-Rong; Neumann, Oara; Polman, Albert; García de Abajo, F. Javier

    2013-01-01

    When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor -a “nanobubble”- surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micron sized bubbles resulting from the coalescence of nanoparticle-“bound” vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications. PMID:23517407

  10. Evolution of light-induced vapor generation at a liquid-immersed metallic nanoparticle.

    PubMed

    Fang, Zheyu; Zhen, Yu-Rong; Neumann, Oara; Polman, Albert; García de Abajo, F Javier; Nordlander, Peter; Halas, Naomi J

    2013-04-10

    When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor-a "nanobubble"-surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micrometer-sized bubbles resulting from the coalescence of nanoparticle-"bound" vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications. PMID:23517407

  11. Current technology in ion and electrothermal propulsion

    NASA Technical Reports Server (NTRS)

    Finke, R. C.; Murch, C. K.

    1973-01-01

    The state of the art and projected developmental trends in the fields of ion and electrothermal propulsion systems intended for use in long and complex earth-orbital missions and interplanetary spacecraft missions are reviewed. The characteristics of existing thrust vectoring systems are outlined, together with data on the 5-cm and 8-cm electron bombardment thrusters, the cesium bombardment ion thruster, and the 8-cm, 15-cm, and 30-cm thruster using xenon propellant. The electrothermal ammonia system and the electrothermal hydrazine system are described, and the principles of propulsion system selection are examined.

  12. All-atomic generation and noise-quadrature filtering of squeezed vacuum in hot Rb vapor

    NASA Astrophysics Data System (ADS)

    Horrom, Travis; Romanov, Gleb; Novikova, Irina; Mikhailov, Eugeniy E.

    2013-01-01

    With our all-atomic squeezing and filtering setup, we demonstrate control over the noise amplitudes and manipulation of the frequency-dependent squeezing angle of a squeezed vacuum quantum state by passing it through an atomic medium with electromagnetically induced transparency (EIT). We generate low sideband frequency squeezed vacuum using the polarization self-rotation effect in a hot Rb vapor cell, and direct it through a second atomic vapor subject to EIT conditions. We use the frequency-dependent absorption of the EIT window to demonstrate an example of squeeze amplitude attenuation and squeeze angle rotation of the quantum noise quadratures of the squeezed probe. These studies have implications for quantum memory and storage as well as gravitational wave interferometric detectors.

  13. Electrothermal blinking vortices for chaotic mixing

    NASA Astrophysics Data System (ADS)

    Loire, Sophie; Kauffmann, Paul; Gimenez, Paul; Meinhart, Carl; Mezic, Igor

    2012-11-01

    We present an experimental and theoretical study of electrothermal chaotic mixing using blinking of asymmetric 2D electrothermal vortices. Electrothermal flows are modelled with 2D finite element method using COMSOL software based on an enhanced electrothermal model. Velocities in top-view and side-view devices are measured by micro particle image velocimetry (μPIV). The experimentally reconstructed velocity profile shows a dramatic asymmetry between the two vortices, in good agreement with the FEM model. The separation line between the two vortices is shifted and tilted making the blinking vortices overlap. We use the mix-variance coefficient (MVC) on experimental particle detection data and numerical trajectory simulations to evaluate mixing at different scales including the layering of fluid interfaces by the flow, a keypoint for efficient mixing. The blinking vortices method greatly improve mixing efficiency. Theoretical, experimental and simulation results of the mixing process will be presented.

  14. A Parylene MEMS Electrothermal Valve

    PubMed Central

    Li, Po-Ying; Givrad, Tina K.; Holschneider, Daniel P.; Maarek, Jean-Michel I.; Meng, Ellis

    2011-01-01

    The first microelectromechanical-system normally closed electrothermal valve constructed using Parylene C is described, which enables both low power (in milliwatts) and rapid operation (in milliseconds). This low-power valve is well suited for applications in wirelessly controlled implantable drug-delivery systems. The simple design was analyzed using both theory and modeling and then characterized in benchtop experiments. Operation in air (constant current) and water (current ramping) was demonstrated. Valve-opening powers of 22 mW in air and 33 mW in water were obtained. Following integration of the valve with catheters, our valve was applied in a wirelessly operated microbolus infusion pump, and the in vivo functionality for the appropriateness of use of this pump for future brain mapping applications in small animals was demonstrated. PMID:21350679

  15. Environmental Chemistry at Vapor/Water Interfaces: Insights from Vibrational Sum Frequency Generation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jubb, Aaron M.; Hua, Wei; Allen, Heather C.

    2012-05-01

    The chemistry that occurs at surfaces has been an intense area of study for many years owing to its complexity and importance in describing a wide range of physical phenomena. The vapor/water interface is particularly interesting from an environmental chemistry perspective as this surface plays host to a wide range of chemistries that influence atmospheric and geochemical interactions. The application of vibrational sum frequency generation (VSFG), an inherently surface-specific, even-order nonlinear optical spectroscopy, enables the direct interrogation of various vapor/aqueous interfaces to elucidate the behavior and reaction of chemical species within the surface regime. In this review we discuss the application of VSFG to the study of a variety of atmospherically important systems at the vapor/aqueous interface. Chemical systems presented include inorganic ionic solutions prevalent in aqueous marine aerosols, small molecular solutes, and long-chain fatty acids relevant to fat-coated aerosols. The ability of VSFG to probe both the organization and reactions that may occur for these systems is highlighted. A future perspective toward the application of VSFG to the study of environmental interfaces is also provided.

  16. Studies on Aspirin Crystals Generated by a Modified Vapor Diffusion Method.

    PubMed

    Mittal, Amit; Malhotra, Deepak; Jain, Preeti; Kalia, Anupama; Shunmugaperumal, Tamilvanan

    2016-08-01

    The objectives of the current investigation were (1) to study the influence of selected two different non-solvents (diethylether and dichloromethane) on the drug crystal formation of a model drug, aspirin (ASP-I) by the modified vapor diffusion method and (2) to characterize and compare the generated crystals (ASP-II and ASP-III) using different analytical techniques with that of unprocessed ASP-I. When compared to the classical vapor diffusion method which consumes about 15 days to generate drug crystals, the modified method needs only 12 h to get the same. Fourier transform-infrared spectroscopy (FT-IR) reveals that the internal structures of ASP-II and ASP-III crystals were identical when compared with ASP-I. Although the drug crystals showed a close similarity in X-ray diffraction patterns, the difference in the relative intensities of some of the diffraction peaks (especially at 2θ values of around 7.7 and 15.5) could be attributed to the crystal habit or crystal size modification. Similarly, the differential scanning calorimetry (DSC) study speculates that only the crystal habit modifications might occur but without involving any change in internal structure of the generated drug polymorphic form I. This is further substantiated from the scanning electron microscopy (SEM) pictures that indicated the formation of platy shape for the ASP-II crystals and needle shape for the ASP-III crystals. In addition, the observed slow dissolution of ASP crystals should indicate polymorph form I formation. Thus, the modified vapor diffusion method could routinely be used to screen and legally secure all possible forms of other drug entities too. PMID:26729528

  17. On line vapor generation of osmium based on solution cathode glow discharge for the determination by ICP-OES.

    PubMed

    Zhu, Zhenli; Huang, Chunying; He, Qian; Xiao, Qing; Liu, Zhifu; Zhang, Suicheng; Hu, Shenghong

    2013-03-15

    A novel plasma induced vapor generation method is proposed to determine osmium in solutions. Without any chemical oxidizing agents, osmium ion can be readily converted to volatile osmium tetraoxide vapor in the solution cathode glow discharge (SCGD) system. The generated osmium vapor is then transported to inductively coupled plasma for determination by optical emission spectrometry. The influences of background electrolyte, carrier gas flow rate, sample flow rate, ICP power and discharge current were investigated. The analytical performances of this proposed technique were evaluated under optimized conditions. The detection limit of Os was calculated to be 0.51 ng mL(-1). The reproducibility, expressed as the relative standard deviation (n=11) of a 2.0 μg mL(-1) standard solution, was 1.9%. This SCGD induced vapor generation is sensitive and simple, oxidation reagents free, providing an alternative analytical method for measuring Os in geological or environmental water samples. PMID:23598105

  18. Scalable generation of multiple quantum correlated beams from hot rubidium vapors

    NASA Astrophysics Data System (ADS)

    Jing, Jietai; Qin, Zhongzhong; Wang, Hailong; Kong, Jia; Cao, Leiming; Zhang, Weiping

    2013-05-01

    Quantum correlation and quantum entanglement shared among multiple quantum nodes are the fundamental ingredients for the future quantum internet. In order to make an efficient quantum interface between multi-mode quantum light sources and the atomic ensemble which has been proven to be a good candidate for quantum memory and quantum repeater, it is necessary to generate the multimode quantum light sources which match the atomic transition lines of the atomic ensemble. Here we present a scalable method for generating the multiple quantum correlated beams by using multiple four wave mixing processes in hot Rubidium vapor and we experimentally showed that the strong quantum correlation among the three bright beams. Their relative intensity difference is -5.6dB below the correspondent shot noise limit and the squeezing from only one vapor cell in such system is -3.5dB. This result agrees with our theoretical prediction that the quantum correlation in our scheme increases as the number of quantum modes increases. Our method also has the advantages of scalability and potential applications in producing multipartite quantum entangled images.

  19. Germanium determination by flame atomic absorption spectrometry: an increased vapor pressure-chloride generation system.

    PubMed

    Kaya, Murat; Volkan, Mürvet

    2011-03-15

    A new chloride generation system was designed for the direct, sensitive, rapid and accurate determination of the total germanium in complex matrices. It was aimed to improve the detection limit of chloride generation technique by increasing the vapor pressure of germanium tetrachloride (GeCl(4)). In order to do so, a novel joint vapor production and gas-liquid separation unit equipped with a home-made oven was incorporated to an ordinary nitrous oxide-acetylene flame atomic absorption spectrometer. Several variables such as reaction time, temperature and acid concentration have been investigated. The linear range for germanium determination was 0.1-10 ng mL(-1) for 1 mL sampling volume with a detection limit (3s) of 0.01 ng mL(-1). The relative standard deviation (RSD) was 2.4% for nine replicates of a 1 ng mL(-1) germanium solution. The method was validated by the analysis of one non-certified and two certified geochemical reference materials, respectively, CRM GSJ-JR-2 (Rhyolite), and GSJ-JR-1 (Rhyolite), and GBW 07107 (Chinese Rock). Selectivity of the method was investigated for Cd(2+), Co(2+), Cu(2+), Fe(3+), Ga(3+), Hg(2+), Ni(2+), Pb(2+), Sn(2+), and Zn(2+) ions and ionic species of As(III), Sb(III), Te(IV), and Se(IV). PMID:21315908

  20. A kinetic model for stress generation in thin films grown from energetic vapor fluxes

    NASA Astrophysics Data System (ADS)

    Chason, E.; Karlson, M.; Colin, J. J.; Magnfält, D.; Sarakinos, K.; Abadias, G.

    2016-04-01

    We have developed a kinetic model for residual stress generation in thin films grown from energetic vapor fluxes, encountered, e.g., during sputter deposition. The new analytical model considers sub-surface point defects created by atomic peening, along with processes treated in already existing stress models for non-energetic deposition, i.e., thermally activated diffusion processes at the surface and the grain boundary. According to the new model, ballistically induced sub-surface defects can get incorporated as excess atoms at the grain boundary, remain trapped in the bulk, or annihilate at the free surface, resulting in a complex dependence of the steady-state stress on the grain size, the growth rate, as well as the energetics of the incoming particle flux. We compare calculations from the model with in situ stress measurements performed on a series of Mo films sputter-deposited at different conditions and having different grain sizes. The model is able to reproduce the observed increase of compressive stress with increasing growth rate, behavior that is the opposite of what is typically seen under non-energetic growth conditions. On a grander scale, this study is a step towards obtaining a comprehensive understanding of stress generation and evolution in vapor deposited polycrystalline thin films.

  1. Generation and multi-pass propagation of a squeezed vacuum field in hot Rb vapor

    NASA Astrophysics Data System (ADS)

    Zhang, Mi; Lanning, R. Nicholas; Xiao, Zhihao; Dowling, Jonathan P.; Novikova, Irina; Mikhailov, Eugeniy E.

    We study a squeezed vacuum field (with reduced quantum noise level) generated in hot Rb vapor via the polarization self-rotation effect. By propagating the strong laser beam through a vapor cell once, we were able to achieve a noise suppression of 1.5-2 dB below shot noise. Our previous experiments showed that the amount of observed squeezing may be limited by the contamination of the squeezed vacuum output with higher-order spatial modes, also generated inside the cell. Here, we investigate whether or not the squeezing can be improved by making the light interact several times with a less dense atomic ensemble. We carry out a comparison of various conditions, e.g. injection power, atomic density, passing numbers etc., and studied their effect on squeezing level and the spatial structure of the output squeezed vacuum field. We believe(or show) optimization of the conditions can lead to higher achievable squeezing which would be very useful for precision metrology and quantum memory applications. This project is supported by AFOSR Grant FA9550-13-1-0098.

  2. Generation and multi-pass propagation of a squeezed vacuum field in hot Rb vapor

    NASA Astrophysics Data System (ADS)

    Zhang, Mi; Lanning, R. Nicholas; Xiao, Zhihao; Dowling, Jonathan P.; Novikova, Irina; Mikhailov, Eugeniy E.

    2016-05-01

    We study a squeezed vacuum field generated in hot Rb vapor via the polarization self-rotation effect. By propagating the strong laser beam through a vapor cell once, we were able to achieve a noise suppression of 2 dB below shot noise. Our previous experiments showed that the amount of observed squeezing may be limited by the contamination of the squeezed vacuum output with higher-order spatial modes, also generated inside the cell. Here, we investigate whether or not the squeezing can be improved by making the light interact several times with a less dense atomic ensemble. We carry out a comparison of various conditions, e.g. injection power, atomic density, passing numbers etc., and studied their effect on squeezing level and the spatial structure of the output squeezed vacuum field. We observe that multiple passages of beam through the medium can lead to an improvement of squeezing, and minimum noise occurs at almost the same effective atomic density for all setups. We show optimization of the conditions can lead to higher achievable squeezing which would be very useful for precision metrology and quantum memory applications. We acknowledge support from AFOSR Grant No. FA9550-13-1- 0098, ARO Grant No. W911NF-13-1-0381, NSF Grant No. 1403105, and the Northrop Grumman Corporation.

  3. Microfluidic pumping optimization in microgrooved channels with ac electrothermal actuations

    NASA Astrophysics Data System (ADS)

    Du, E.; Manoochehri, Souran

    2010-01-01

    An optimization methodology is developed and applied to an ac electrothermal pump design with patterned microgrooved features. The microgrooved configuration can overcome the restrictions of the conventional planar configuration on pumping performance by diminishing fast backward flows and suppressing prolonged streamlines. At all frequency excitations (0.2-1000 MHz) and ion concentration conditions (5×10-3-0.1 M), the optimum microgrooved configuration generates much faster flow rate than planar configuration. This happens without additional increases in the maximum temperature values. The effects of elevated temperature on ac ET flow behavior is investigated and analyzed.

  4. Demonstration of a vapor density monitoring system using UV radiation generated from quasi-phasematched SHG waveguide devices

    SciTech Connect

    Galanti, S.A.; Berzins, L.V.; Brown, J.B.; Tamosaitis, R.S.; Bortz, M.L.; Day, T.; Fejer, M.M.; Wang, W.

    1996-01-29

    Many industrial applications require non-intrusive diagnostics for process monitoring and control. One example is the physical vapor deposition of titanium alloys. In this paper we present a system based on laser absorption spectroscopy for monitoring titanium vapor. Appropriate transitions for monitoring high rate vaporization of titanium require extension of available IR diode technology to the UV. The heart of this vapor density monitoring system is the 390nm radiation generated from quasi-phase matched interactions within periodically poled waveguides. In this paper, key system components of a UV laser absorption spectroscopy based system specific for titanium density monitoring are described. Analysis is presented showing the minimum power levels necessary from the ultraviolet laser source. Performance data for prototype systems using second harmonic generation (SHG) waveguide technology is presented. Application of this technology to other alloy density monitoring systems is discussed.

  5. Determination of total mercury in biological tissue by isotope dilution ICPMS after UV photochemical vapor generation.

    PubMed

    Liu, Rui; Xu, Mo; Shi, Zeming; Zhang, Jiayun; Gao, Ying; Yang, Lu

    2013-12-15

    A method is developed for the determination of trace mercury in biological samples using photo chemical vapor generation (PVG) and isotope dilution inductively coupled plasma mass spectrometry (ID ICPMS) detection. Biological tissues were solubilized in formic acid. Subsequently, the sample solutions were exposed to an ultraviolet (UV) source for the reduction of mercury into vapor species prior to ICPMS measurements. The formic acid served not only as a tissue solubilizer in the sample preparation procedure, but also as a photochemical reductant for mercury in the PVG process. The problem arising from the opaque formic acid digested solution was efficiently solved by using ID method. The optimum conditions for sample treatment and PVG were investigated. A limit of detection (LOD) of 0.5 pg g(-1), based on an external calibration, provided 350-fold improvement over that obtained by utilizing conventional pneumatic nebulization sample introduction. Method validation was demonstrated by the determination of total mercury in several biological tissue certified reference materials (CRMs). The results were in good agreement with the certified values. PMID:24209355

  6. A Petroleum Vapor Intrusion Model Involving Upward Advective Soil Gas Flow Due to Methane Generation.

    PubMed

    Yao, Yijun; Wu, Yun; Wang, Yue; Verginelli, Iason; Zeng, Tian; Suuberg, Eric M; Jiang, Lin; Wen, Yuezhong; Ma, Jie

    2015-10-01

    At petroleum vapor intrusion (PVI) sites at which there is significant methane generation, upward advective soil gas transport may be observed. To evaluate the health and explosion risks that may exist under such scenarios, a one-dimensional analytical model describing these processes is introduced in this study. This new model accounts for both advective and diffusive transport in soil gas and couples this with a piecewise first-order aerobic biodegradation model, limited by oxygen availability. The predicted results from the new model are shown to be in good agreement with the simulation results obtained from a three-dimensional numerical model. These results suggest that this analytical model is suitable for describing cases involving open ground surface beyond the foundation edge, serving as the primary oxygen source. This new analytical model indicates that the major contribution of upward advection to indoor air concentration could be limited to the increase of soil gas entry rate, since the oxygen in soil might already be depleted owing to the associated high methane source vapor concentration. PMID:26322369

  7. Electrothermal instability mitigation by using thick dielectric coatings on magnetically imploded conductors.

    PubMed

    Peterson, Kyle J; Awe, Thomas J; Yu, Edmund P; Sinars, Daniel B; Field, Ella S; Cuneo, Michael E; Herrmann, Mark C; Savage, Mark; Schroen, Diana; Tomlinson, Kurt; Nakhleh, Charles

    2014-04-01

    Recent experiments on Sandia's Z facility have confirmed simulation predictions of dramatically reduced instability growth in solid metallic rods when thick dielectric coatings are used to mitigate density perturbations arising from an electrothermal instability. These results provide further evidence that the inherent surface roughness as a result of target fabrication is not the dominant seed for the growth of magneto-Rayleigh-Taylor instabilities in liners with carefully machined smooth surfaces, but rather electrothermal instabilities that form early in the electrical current pulse as Joule heating melts and vaporizes the liner surface. These results suggest a new technique for substantially reducing the integral magneto-Rayleigh-Taylor instability growth in magnetically driven implosions, such as cylindrical dynamic material experiments and inertial confinement fusion concepts. PMID:24745432

  8. Hemozoin-generated vapor nanobubbles for transdermal reagent- and needle-free detection of malaria

    PubMed Central

    Lukianova-Hleb, Ekaterina Y.; Campbell, Kelly M.; Constantinou, Pamela E.; Braam, Janet; Olson, John S.; Ware, Russell E.; Sullivan, David J.; Lapotko, Dmitri O.

    2014-01-01

    Successful diagnosis, screening, and elimination of malaria critically depend on rapid and sensitive detection of this dangerous infection, preferably transdermally and without sophisticated reagents or blood drawing. Such diagnostic methods are not currently available. Here we show that the high optical absorbance and nanosize of endogenous heme nanoparticles called “hemozoin,” a unique component of all blood-stage malaria parasites, generates a transient vapor nanobubble around hemozoin in response to a short and safe near-infrared picosecond laser pulse. The acoustic signals of these malaria-specific nanobubbles provided transdermal noninvasive and rapid detection of a malaria infection as low as 0.00034% in animals without using any reagents or drawing blood. These on-demand transient events have no analogs among current malaria markers and probes, can detect and screen malaria in seconds, and can be realized as a compact, easy-to-use, inexpensive, and safe field technology. PMID:24379385

  9. Molecular dynamics study of two-dimensional sum frequency generation spectra at vapor/water interface

    SciTech Connect

    Ishiyama, Tatsuya; Morita, Akihiro; Tahara, Tahei

    2015-06-07

    Two-dimensional heterodyne-detected vibrational sum frequency generation (2D HD-VSFG) spectra at vapor/water interface were studied by molecular dynamics (MD) simulation with a classical flexible and nonpolarizable model. The present model well describes the spectral diffusion of 2D infrared spectrum of bulk water as well as 2D HD-VSFG at the interface. The effect of isotopic dilution on the 2D HD-VSFG was elucidated by comparing the normal (H{sub 2}O) water and HOD water. We further performed decomposition analysis of 2D HD-VSFG into the hydrogen-bonding and the dangling (or free) OH vibrations, and thereby disentangled the different spectral responses and spectral diffusion in the 2D HD-VSFG. The present MD simulation demonstrated the role of anharmonic coupling between these modes on the cross peak in the 2D HD-VSFG spectrum.

  10. Net vapor generation point in boiling flow of trichlorotrifluoroethane at high pressures

    NASA Technical Reports Server (NTRS)

    Dougall, R. S.; Lippert, T. E.

    1973-01-01

    The conditions at which the void in subcooled boiling starts to undergo a rapid increase were studied experimentally. The experiments were performed in a 12.7 x 9.5 mm rectangular channel. Heating was from a 3.2 mm wide strip embedded in one wall. The pressure ranged from 9.45 to 20.7 bar, mass velocity from 600 to 7000 kg/sq m sec, and subcooling from 16 to 67 C. Photographs were used to determine when detached bubbles first appeared in the bulk flow. Measurements of bubble layer thickness along the wall were also made. Results showed that the point of net vapor generation is close to the occurrence of fully-developed boiling.

  11. Hemozoin-generated vapor nanobubbles for transdermal reagent- and needle-free detection of malaria.

    PubMed

    Lukianova-Hleb, Ekaterina Y; Campbell, Kelly M; Constantinou, Pamela E; Braam, Janet; Olson, John S; Ware, Russell E; Sullivan, David J; Lapotko, Dmitri O

    2014-01-21

    Successful diagnosis, screening, and elimination of malaria critically depend on rapid and sensitive detection of this dangerous infection, preferably transdermally and without sophisticated reagents or blood drawing. Such diagnostic methods are not currently available. Here we show that the high optical absorbance and nanosize of endogenous heme nanoparticles called "hemozoin," a unique component of all blood-stage malaria parasites, generates a transient vapor nanobubble around hemozoin in response to a short and safe near-infrared picosecond laser pulse. The acoustic signals of these malaria-specific nanobubbles provided transdermal noninvasive and rapid detection of a malaria infection as low as 0.00034% in animals without using any reagents or drawing blood. These on-demand transient events have no analogs among current malaria markers and probes, can detect and screen malaria in seconds, and can be realized as a compact, easy-to-use, inexpensive, and safe field technology. PMID:24379385

  12. Method for the generation of variable density metal vapors which bypasses the liquidus phase

    DOEpatents

    Kunnmann, Walter; Larese, John Z.

    2001-01-01

    The present invention provides a method for producing a metal vapor that includes the steps of combining a metal and graphite in a vessel to form a mixture; heating the mixture to a first temperature in an argon gas atmosphere to form a metal carbide; maintaining the first temperature for a period of time; heating the metal carbide to a second temperature to form a metal vapor; withdrawing the metal vapor and the argon gas from the vessel; and separating the metal vapor from the argon gas. Metal vapors made using this method can be used to produce uniform powders of the metal oxide that have narrow size distribution and high purity.

  13. Heat exchanger for electrothermal devices

    SciTech Connect

    Zavesky, R.J.; Sovey, J.S.; Mirtich, M.J.; Marinos, C.; Penko, P.F.

    1986-09-02

    A heat exchanger is described for heating a gaseous propellant to a temperature between about 200/sup 0/C and about 2200/sup 0/C in an electrothermal thruster having a nozzle comprising a hollow housing forming a cylindrical chamber adjacent to the nozzle, the hollow housing having a textured inner surface to provide high absorptivity and an oppositely disposed textured outer surface to provide high emissivity, an outer housing surrounding the cylindrical chamber in spaced relationship thereto thereby forming an annular chamber for conducting the gaseous propellant to the nozzle, a porous heat exchanger material selected from the group consisting of refractories, ceramics, and cermets contained within the annular chamber, housing a wire coiled about the outer surface of the hollow housing in engagement with the outer housing for providing a lengthened spiral flow path for the propellant to the annular chamber, an electrical heating comprising a coiled tube having a wall thickness of about 0.25 mm and a textured surface for providing high emissivity mounted within the cylindrical chamber in spaced relationship with the textured inner surface for radiatively heating the hollow housing and heat exchanger material without contacting the gaseous propellant, means for supplying a gaseous propellant to the lengthened spiral flow path and seal annular chamber whereby the propellant is uniformly heated by the hollow housing and the porous heat exchanger material as it flows therethrough in a minimum gas path length, and a thermal choke formed in the electrical heating element adjacent to the coiled wire for reducing conducted thermal energy.

  14. High-speed microjet generation using laser-induced vapor bubbles

    NASA Astrophysics Data System (ADS)

    Oudalov, Nikolai; Tagawa, Yoshiyuki; Peters, Ivo; Visser, Claas-Willem; van der Meer, Devaraj; Prosperetti, Andrea; Sun, Chao; Lohse, Detlef

    2011-11-01

    The generation and evolution of microjets are studied both experimentally and numerically. The jets are generated by focusing a laser pulse into a microscopic capillary tube (~50 μm) filled with water-based red dye. A vapor bubble is created instantly after shooting the laser (<1 μs), sending out a shockwave towards the curved free surface at which the high-speed microjet forms. The process of jet formation is captured using high-speed recordings at 1.0 × 106 fps. The velocity of the microjets can reach speeds of ~850 m/s while maintaining a very sharp geometry. The high-speed recordings enable us to study the effect of several parameters on the jet velocity, e.g. the absorbed energy and the distance between the laser spot and the free surface.The results show a clear dependence on these variables, even for supersonic speeds. Comparisons with numerical simulations confirm the nature of these dependencies.

  15. Use of a solution cathode glow discharge for cold vapor generation of mercury with determination by ICP-atomic emission spectrometry.

    PubMed

    Zhu, Zhenli; Chan, George C-Y; Ray, Steven J; Zhang, Xinrong; Hieftje, Gary M

    2008-09-15

    A novel vapor-generation technique is described for mercury determination in aqueous solutions. Without need for a chemical reducing agent, dissolved mercury species are converted to volatile Hg vapor in a solution cathode glow discharge. The generated Hg vapor is then transported to an inductively coupled plasma for determination by atomic emission spectrometry. Mercury vapor is readily generated from a background electrolyte containing 0.1 M HNO 3. Vapor generation efficiency was found to be higher by a factor of 2-3 in the presence of low molecular weight organic acids (formic or acetic acids) or alcohols (ethanol). Optimal conditions for discharge-induced vapor generation and reduced interference from concomitant inorganic ions were also identified. However, the presence of chloride ion reduces the efficiency of Hg-vapor generation. In the continuous sample introduction mode, the detection limit was found to be 0.7 microg L (-1), and repeatability was 1.2% RSD ( n = 11) for a 20 microg L (-1) standard. In comparison with other vapor generation methods, it offers several advantages: First, it is applicable to both inorganic and organic Hg determination; organic mercury (thiomersal) can be directly transformed into volatile Hg species without the need for prior oxidation. Second, the vapor-generation efficiency is high; the efficiency (with formic acid as a promoter) is superior to that of conventional SnCl 2-HCl reduction. Third, the vapor generation is extremely rapid and therefore is easy to couple with flow injection. The method is sensitive and simple in operation, requires no auxiliary reagents, and serves as a useful alternative to conventional vapor generation for ultratrace Hg determination. PMID:18710258

  16. Electrothermal energy conversion using electron gas volumetric change inside semiconductors

    NASA Astrophysics Data System (ADS)

    Yazawa, K.; Shakouri, A.

    2016-07-01

    We propose and analyze an electrothermal energy converter using volumetric changes in non-equilibrium electron gas inside semiconductors. The geometric concentration of electron gas under an electric field increases the effective pressure of the electrons, and then a barrier filters out cold electrons, acting like a valve. Nano- and micro-scale features enable hot electrons to arrive at the contact in a short enough time to avoid thermalization with the lattice. Key length and time scales, preliminary device geometry, and anticipated efficiency are estimated for electronic analogs of Otto and Brayton power generators and Joule-Thomson micro refrigerators on a chip. The power generators convert the energy of incident photons from the heat source to electrical current, and the refrigerator can reduce the temperature of electrons in a semiconductor device. The analytic calculations show that a large energy conversion efficiency or coefficient of performance may be possible.

  17. Improving Battery Design with Electro-Thermal Modeling

    SciTech Connect

    Bharathan, D.; Pesaran, A.; Vlahinos, A.; Kim, G.-H.

    2005-01-01

    Operating temperature greatly affects the performance and life of batteries in electric and hybrid vehicles. Increased attention is necessary to battery thermal management. Electrochemical models and finite element analysis tools are available for predicting the thermal performance of batteries, but each has limitations. In this study we describe an electro-thermal finite element approach that predicts the thermal performance of a cell or module with realistic geometry. To illustrate the process, we simulated the thermal performance of two generations of Panasonic prismatic nickel-metal-hydride modules used in the Toyota Prius. The model showed why the new generation of Panasonic modules had better thermal performance. Thermal images from two battery modules under constant current discharge indicate that the model predicts the experimental trend reasonably well.

  18. Experimental Generation of Multiple Quantum Correlated Beams from Hot Rubidium Vapor

    NASA Astrophysics Data System (ADS)

    Qin, Zhongzhong; Cao, Leiming; Wang, Hailong; Marino, A. M.; Zhang, Weiping; Jing, Jietai

    2014-07-01

    Quantum correlations and entanglement shared among multiple quantum modes are important for both fundamental science and the future development of quantum technologies. This development will also require an efficient quantum interface between multimode quantum light sources and atomic ensembles, which makes it necessary to implement multimode quantum light sources that match the atomic transitions. Here, we report on such a source that provides a method for generating quantum correlated beams that can be extended to a large number of modes by using multiple four-wave mixing (FWM) processes in hot rubidium vapor. Experimentally, we show that two cascaded FWM processes produce strong quantum correlations between three bright beams but not between any two of them. In addition, the intensity-difference squeezing is enhanced with the cascaded system to -7.0±0.1 dB from the -5.5±0.1/-4.5±0.1 dB squeezing obtained with only one FWM process. One of the main advantages of our system is that as the number of quantum modes increases, so does the total degree of quantum correlations. The proposed method is also immune to phase instabilities due to its phase insensitive nature, can easily be extended to multiple modes, and has potential applications in the production of multiple quantum correlated images.

  19. Near-Infrared-Activated Nanocalorifiers in Microcapsules: Vapor Bubble Generation for In Vivo Enhanced Cancer Therapy.

    PubMed

    Shao, Jingxin; Xuan, Mingjun; Dai, Luru; Si, Tieyan; Li, Junbai; He, Qiang

    2015-10-19

    Photothermal therapy based on gold nanostructures has been widely investigated as a state-of-the-art noninvasive therapy approach. Because single nanoparticles cannot harvest sufficient energy, self-assemblies of small plasmonic particles into large aggregates are required for enhanced photothermal performance. Self-assembled gold nanorods in lipid bilayer-modified microcapsules are shown to localize at tumor sites, generate vapor bubbles under near-infrared light exposure, and subsequently damage tumor tissues. The polyelectrolyte multilayer enables dense packing of gold nanorods during the assembly process, which leads to the formation of vapor bubbles around the excited capsules. The resulting vapor bubbles achieve a high efficiency of suppressing tumor growth compared to single gold nanorods. In vivo experiments demonstrated the ability of soft-polymer multilayer microcapsules to cross the biological barriers of the body and localize at target tissues. PMID:26306782

  20. Characterization of acoustic droplet vaporization for control of bubble generation under flow conditions.

    PubMed

    Kang, Shih-Tsung; Huang, Yi-Luan; Yeh, Chih-Kuang

    2014-03-01

    This study investigated the manipulation of bubbles generated by acoustic droplet vaporization (ADV) under clinically relevant flow conditions. Optical microscopy and high-frequency ultrasound imaging were used to observe bubbles generated by 2-MHz ultrasound pulses at different time points after the onset of ADV. The dependence of the bubble population on droplet concentration, flow velocity, fluid viscosity and acoustic parameters, including acoustic pressure, pulse duration and pulse repetition frequency, was investigated. The results indicated that post-ADV bubble growth spontaneously driven by air permeation markedly affected the bubble population after insonation. The bubbles can grow to a stable equilibrium diameter as great as twice the original diameter in 0.5-1 s, as predicted by the theoretical calculation. The growth trend is independent of flow velocity, but dependent on fluid viscosity and droplet concentration, which directly influence the rate of gas uptake by bubbles and the rate of gas exchange across the wall of the semipermeable tube containing the bubbles and, hence, the gas content of the host medium. Varying the acoustic pressure does not markedly change the formation of bubbles as long as the ADV thresholds of most droplets are reached. Varying pulse duration and pulse repetition frequency markedly reduces the number of bubbles. Lengthening pulse duration favors the production of large bubbles, but reduces the total number of bubbles. Increasing the PRF interestingly provides superior performance in bubble disruption. These results also suggest that an ADV bubble population cannot be assessed simply on the basis of initial droplet size or enhancement of imaging contrast by the bubbles. Determining the optimal acoustic parameters requires careful consideration of their impact on the bubble population produced for different application scenarios. PMID:24433748

  1. Photochemical vapor generation of lead for inductively coupled plasma mass spectrometric detection

    NASA Astrophysics Data System (ADS)

    Duan, Hualing; Zhang, Ningning; Gong, Zhenbin; Li, Weifeng; Hang, Wei

    2016-06-01

    Photochemical vapor generation (PCVG) of lead was successfully achieved with a simplified and convenient system, in which only low molecular weight organic acid and a high-efficiency photochemical reactor were needed. The reactor was used to generate lead volatile species when a solution of lead containing a small amount of low molecular weight organic acid was pumped through. Several factors, including the concentration of acetic acid, the concentration of hydrochloride acid, and the irradiation time of UV light were optimized. Under the optimal conditions, including the addition of 0.90% (v/v) acetic acid and 0.03% (v/v) hydrochloride acid, and irradiation time of 28 s, intense and repeatable signal of lead volatile species was successfully obtained and identified with inductively coupled plasma mass spectrometry (ICPMS). In addition, the effects from inorganic anions and transition metal ions, including Cl-, NO3-, SO42 -, Cu2 +, Fe3 +, Co2 + and Ni2 +, were investigated, which suggests that their suppression to the PCVG of lead was in the order of Cl- < SO42 - < NO3- for anions and Ni2 +, Co2 + < Fe3 + < Cu2 + for transition metal ions. Under optimized conditions, relative standard derivation (RSD) of 4.4% was achieved from replicate measurements (n = 5) of a standard solution of 0.1 μg L- 1 lead. And, the limit of quantitation (LOQ, 10σ) of 0.012 μg L- 1 lead was obtained using this method and the method blank could be easily controlled down to 0.023 μg L- 1. To validate applicability of this method, it was also employed for the determination of lead in tap water, rain water and lake water.

  2. Nanostructured carbon materials based electrothermal air pump actuators

    NASA Astrophysics Data System (ADS)

    Liu, Qing; Liu, Luqi; Kuang, Jun; Dai, Zhaohe; Han, Jinhua; Zhang, Zhong

    2014-05-01

    Actuator materials can directly convert different types of energy into mechanical energy. In this work, we designed and fabricated electrothermal air pump-type actuators by utilization of various nanostructured carbon materials, including single wall carbon nanotubes (SWCNTs), reduced graphene oxide (r-GO), and graphene oxide (GO)/SWCNT hybrid films as heating elements to transfer electrical stimulus into thermal energy, and finally convert it into mechanical energy. Both the actuation displacement and working temperature of the actuator films show the monotonically increasing trend with increasing driving voltage within the actuation process. Compared with common polymer nanocomposites based electrothermal actuators, our actuators exhibited better actuation performances with a low driving voltage (<10 V), large generated stress (tens of MPa), high gravimetric density (tens of J kg-1), and short response time (few hundreds of milliseconds). Besides that, the pump actuators exhibited excellent stability under cyclic actuation tests. Among these actuators, a relatively larger actuation strain was obtained for the r-GO film actuator due to the intrinsic gas-impermeability nature of graphene platelets. In addition, the high modulus of the r-GO and GO/SWCNT films also guaranteed the large generated stress and high work density. Specifically, the generated stress and gravimetric work density of the GO/SWCNT hybrid film actuator could reach up to more than 50 MPa and 30 J kg-1, respectively, under a driving voltage of 10 V. The resulting stress value is at least two orders of magnitude higher than that of natural muscles (~0.4 MPa).Actuator materials can directly convert different types of energy into mechanical energy. In this work, we designed and fabricated electrothermal air pump-type actuators by utilization of various nanostructured carbon materials, including single wall carbon nanotubes (SWCNTs), reduced graphene oxide (r-GO), and graphene oxide (GO)/SWCNT hybrid

  3. Electrothermal micromixing in 96 well plate

    NASA Astrophysics Data System (ADS)

    Kauffmann, Paul; Loire, Sophie; Mezic, Igor

    2011-11-01

    Diagnostic and pharmacology processes could be greatly accelerated by appropriate mixing. Here electrothermal flows are explored to provide mixing of conductive physiological solutions (=1.6 S/m) in a 96 well plate. Three interdigitated electrodes provide an electric field (< 15Vpp, 1MHz) beneath each well. Polarization and conduction phenomenon of the fluid in a well will be first modeled numerically and compared to an electrical circuit model. Due to high conductivity and permittivity of the fluid, the impedance of the array of filled wells collapse dramatically (96 wells: R = 1Ohm, C=250nF). The power supply challenges accordingly raised by arrays of electrothermal micromixers will be then analyzed. The efficiency of different methods of mixing in those wells will be also compared: the addition of low frequency signal leading to AC electro-osmotic perturbations, a blinking vortices method. The experimental results will be compared to simulations.

  4. Intradiscal electrothermal therapy: a preliminary report.

    PubMed

    Singh, V

    2000-10-01

    Internal disc disruption is a common cause of disabling low back pain in a substantial number of young, healthy adults. A clinical diagnosis of internal disruption, in absence of objective clinical findings, is convincingly established only by means of provocation discography. Intradiscal electrothermal therapy has been shown to be effective in managing chronic disabling discogenic pain. This prospective pilot outcome study was designed to investigate the effectiveness of intradiscal electrothermal annuloplasty in a series of patients with chronic functionally disabling discogenic low back pain. The results showed greater than 50% pain relief in 67% of the patients. In addition, a significant decrease in visual analog pain scores was also seen. Further, the assessment of functional status showed significant improvement with standing and walking, whereas sitting also demonstrated significant improvement in 62% of the patients, though it was not statistically significant. No complications were noted in the perioperative period or during the follow-up period. In conclusion, intradiscal electrothermal therapy is a safe and effective procedure in patients suffering with chronic functionally limiting discogenic pain who fail to respond to aggressive conservative modalities of treatments as well as interventional therapy with injections. PMID:16906178

  5. Comment on "Tunable generation and adsorption of energetic compounds in the vapor phase at trace levels: A tool for testing and developing sensitive and selective substrates for explosive detection"

    SciTech Connect

    Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

    2013-02-13

    The evaluation of developed technologies and research on new detection approaches require the ability to generate explosive vapors in the gas phase. In this correspondence, the authors comment on a technical note describing a vaopr generator, discuss safety issues associated with explosives for vapor generators, and provide a concise review of vapor generators for explosive compounds. Approaches to measuring or monitoring the output of a vapor generators are also discussed.

  6. An electrochemical flow-cell for permanent modification of graphite tube with palladium for mercury determination by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Moreno, Ruben G. M.; de Oliveira, Elisabeth; Pedrotti, Jairo J.; Oliveira, Pedro V.

    2002-04-01

    An electrochemical procedure for palladium deposition on the inner surface of pyrolytic graphite-coated tubes for permanent chemical modification and a cold vapor generation system for the pre-concentration and determination of mercury trace levels in rain, potable, and non-potable water and lake sediment by electrothermal atomic absorption spectrometry is proposed. A tubular electrochemical flow-cell was assembled on the original geometry of the graphite tube, which operated as the working electrode. A stainless steel tube, positioned downstream from the working electrode, was used as the auxiliary electrode. The applied potential was measured against a micro Ag/AgCl (sat) reference electrode inserted in the auxiliary electrode. Palladium solution in acetate buffer (100 mmol l -1, pH=4.8), flowing at 0.5 ml min -1 for 60 min was used to perform the electrodeposition. A homemade cold vapor generation system composed of a peristaltic pump, an injector-commutator, a flow meter and a disposable polyethylene gas-liquid separator flask (approx. 4.0 ml volume) were used. Volumes of 1.0 ml of reagent (2.0% w/v NaBH 4 in 0.10 mol l -1 of NaOH) and 1.0 ml of reference or sample solution in 0.25 mol l -1 of HNO 3 were carried to the gas-liquid separator using the peristaltic pump. The mercury vapor was carried out to the modified graphite tube by argon flow (200 ml min -1), and pre-concentrated for 120 s. The characteristic mass for 1.0 ml of reference solution was 26 pg (R.S.D.=0.12%, n=5). The detection limit obtained was 93 pg ( n=20, 3δ). The reliability of the entire procedure was confirmed by addition and recovery tests and cold vapor atomic absorption spectrometry.

  7. Determination of Hg and Pb in fuels by inductively coupled plasma mass spectrometry using flow injection chemical vapor generation.

    PubMed

    Chen, Feng-yi; Jiang, Shiuh-Jen

    2009-12-01

    An isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Hg and Pb in fuels using flow injection vapor generation (VG) as the sample introduction system. A simple and inexpensive in-situ nebulizer/vapor generator was employed in this study. An emulsion containing 10% v/v fuel, 2% m/v Triton X-100 and 1.0% m/v tartaric acid was injected into VG-ICP-MS system for the determination of Hg and Pb. Sodium borohydride was used for vapor generation. Since the sensitivities of Hg and Pb in emulsion and those in aqueous solution are quite different, isotope dilution and standard addition methods were used for the determination of Hg and Pb in selected fuel samples. The influences of vapor generation conditions and emulsion preparation on the ion signals are reported. This method has been applied for the determination of Hg and Pb in various fuel samples such as diesel, gasoline and engine oil obtained locally. The analytical results obtained by isotope dilution and standard addition methods were in good agreement with each other and also with those of digested samples analyzed by pneumatic nebulization ICP-MS. Under the optimum operating conditions, the detection limits obtained were 0.02 and 0.03 ng mL(-1) for Hg and Pb, respectively, in prepared emulsified solutions, corresponding to 0.2 and 0.3 ng mL(-1) of Hg and Pb, respectively, in the original fuel samples. PMID:20009337

  8. Electrothermal instability growth in magnetically driven pulsed power liners

    SciTech Connect

    Peterson, Kyle J.; Sinars, Daniel B.; Yu, Edmund P.; Herrmann, Mark C.; Cuneo, Michael E.; Slutz, Stephen A.; Smith, Ian C.; Atherton, Briggs W.; Knudson, Marcus D.; Nakhleh, Charles

    2012-09-15

    This paper explores the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. Comparatively little is known about these types of instabilities compared to the well known Magneto-Rayleigh-Taylor (MRT) instability. We present simulations that show electrothermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent MRT instability growth. We also present the results of several experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns risetime current pulse. These experiments show excellent agreement with electrothermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone.

  9. Electrothermal instability growth in magnetically driven pulsed power liners

    NASA Astrophysics Data System (ADS)

    Peterson, Kyle J.; Sinars, Daniel B.; Yu, Edmund P.; Herrmann, Mark C.; Cuneo, Michael E.; Slutz, Stephen A.; Smith, Ian C.; Atherton, Briggs W.; Knudson, Marcus D.; Nakhleh, Charles

    2012-09-01

    This paper explores the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. Comparatively little is known about these types of instabilities compared to the well known Magneto-Rayleigh-Taylor (MRT) instability. We present simulations that show electrothermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent MRT instability growth. We also present the results of several experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns risetime current pulse. These experiments show excellent agreement with electrothermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone.

  10. Three-dimensional time-dependent computer modeling of the electrothermal atomizers for analytical spectrometry

    NASA Astrophysics Data System (ADS)

    Tsivilskiy, I. V.; Nagulin, K. Yu.; Gilmutdinov, A. Kh.

    2016-02-01

    A full three-dimensional nonstationary numerical model of graphite electrothermal atomizers of various types is developed. The model is based on solution of a heat equation within solid walls of the atomizer with a radiative heat transfer and numerical solution of a full set of Navier-Stokes equations with an energy equation for a gas. Governing equations for the behavior of a discrete phase, i.e., atomic particles suspended in a gas (including gas-phase processes of evaporation and condensation), are derived from the formal equations molecular kinetics by numerical solution of the Hertz-Langmuir equation. The following atomizers test the model: a Varian standard heated electrothermal vaporizer (ETV), a Perkin Elmer standard THGA transversely heated graphite tube with integrated platform (THGA), and the original double-stage tube-helix atomizer (DSTHA). The experimental verification of computer calculations is carried out by a method of shadow spectral visualization of the spatial distributions of atomic and molecular vapors in an analytical space of an atomizer.

  11. Optimization of Fusion Pellet Launch Velocity in an Electrothermal Mass Accelerator

    NASA Astrophysics Data System (ADS)

    Gebhart, T. E.; Holladay, R. T.; Esmond, M. J.; Winfrey, A. L.

    2013-10-01

    Electrothermal mass accelerators, based on capillary discharges, that form a plasma propelling force from the ablation of a low-z liner material are candidates for fuelling magnetic fusion reactors. As lithium is considered a fusion fuel and not an impurity, lithium hydride and lithium deuteride can serve as good ablating liners for plasma formation in an electrothermal plasma source to propel fusion pellets. A comprehensive study of solid lithium hydride and deuteride as liner materials to generate a plasma to propel cryogenic fuel pellets is presented here. This study was conducted using the ETFLOW capillary discharge code. Relationships between propellants, source and barrel geometry, pellet volume and aspect ratio, and pellet velocity are determined for pellets ranging in volume from 5 to 100 mm3.

  12. Multivariate optimization of mercury determination by flow injection-cold vapor generation-inductively coupled plasma optical emission spectrometry.

    PubMed

    dos Santos, Vanessa Cristina Gonçalves; Grassi, Marco Tadeu; de Campos, Mônica Soares; Peralta-Zamora, Patricio Guillermo; Abate, Gilberto

    2012-10-01

    In this work a procedure for mercury determination by Flow Injection-Cold Vapor Generation-Inductively Coupled Plasma Optical Emission Spectrometry (FI-CVG-ICP OES) has been developed. The system uses a small homemade glass separator constructed to drive the Hg vapor to the plasma. An evolutionary operation factorial design was used to evaluate the optimal experimental conditions for mercury vapor generation, aiming at the low consumption of reagents, the improvement of the analytical signal and consequently greater sensitivity. The procedure allowed the determination of mercury and showed excellent linearity for the concentration range from 0.50 μg L(-1) to 100.0 μg L(-1), with Limits of Detection (LOD) and Quantification (LOQ) of 0.11 μg L(-1) and 0.36 μg L(-1), respectively, and a sampling rate of 36 analyses per hour. The optimized procedure showed good accuracy and precision, and the method was validated by the analysis of two certified reference materials: Buffalo River Sediment (NIST 2704) and human hair (IAEA 085). A good agreement with the certified values was achieved, with recovery values of 99% and 98% and relative standard deviation close to 2%. PMID:22870503

  13. Highly vibrationally excited CO generated in a low-temperature chemical reaction between carbon vapor and molecular oxygen

    NASA Astrophysics Data System (ADS)

    Jans, E.; Frederickson, K.; Yurkovich, M.; Musci, B.; Rich, J. W.; Adamovich, I. V.

    2016-08-01

    A chemical flow reactor is used to study the vibrational population distribution of CO produced by a reaction between carbon vapor generated in an arc discharge and molecular oxygen. The results demonstrate formation of highly vibrationally excited CO, up to vibrational level v = 14, at low temperatures, T = 400-450 K, with population inversion at v = 4-7, in a collision-dominated environment, 15-20 Torr. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of reaction enthalpy. The results show feasibility of development of a new CO chemical laser using carbon vapor and oxygen as reactants.

  14. Predicted electrothermal deicing of aircraft blades

    NASA Technical Reports Server (NTRS)

    Keith, T. G., Jr.; Masiulaniec, K. C.; Dewitt, K. J.; Chao, D. F.

    1984-01-01

    A finite difference method is presented for the transient two-dimensional simulation of an electrothermal de-icer pad of an aircraft wing or blade. The irregular geometry of the composite ice laden blade is handled by use of a body fitted coordinate transformation. By this approach the various blade layers are mapped into a set of stacked rectangular strips in which the numerical solution takes place. Several heat conduction examples are presented in order to demonstrate the accuracy of the numerical procedure. Ice melting time predictions are made and compared to earlier predictions where possible. Finally, a new graphical presentation of thermal results is shown.

  15. Microwave electrothermal thruster performance in helium gas

    SciTech Connect

    Whitehair, S.; Asmussen, J.; Nakanishi, S.

    1987-04-01

    The microwave electrothermal thruster presented uses an internally tuned, single-mode cylindrical cavity applicator to focus and match microwave energy into an electrodeless, high pressure flowing gas discharge that is located within a quartz discharge chamber. Experimental measurements of microwave coupling efficiency, thruster energy efficiency, and specific impulse, are obtained for N and He discharges; the efficiency of microwave energy transfer to the discharge is found to be of the order of 95 percent. Higher temperature nozzle materials and more efficient discharge chambers will further enhance performance. 25 references.

  16. Treatment of multilevel degenerative disc disease with intradiscal electrothermal therapy.

    PubMed

    Malik, K

    2007-04-01

    Intradiscal electrothermal therapy is a frequently performed procedure for the pain of internal disc disruption. It is typically performed on one to two discs; the discal treatment is followed by a long period of rest and rehabilitation. In patients with multilevel disc disease, intradiscal electrothermal therapy is either not contemplated or only one to two discs are treated at a time. This approach therefore either denies these patients the potential benefits of intradiscal electrothermal therapy or significantly prolongs the period of pain and disability. A 25-year-old female patient presented with internal disc disruption at four lumbar disc levels, diagnosed by provocative discography and post discography CT scan. All these discs were treated simultaneously by intradiscal electrothermal therapy. The patient tolerated the procedure well and responded favourably with significant and prolonged decrease in her symptoms. She reported sustained reduction in her pain and showed no clinical evidence of early neurological or infectious complications during 18 months of follow-up. This report indicates that intradiscal electrothermal therapy can be performed at multiple levels at a single sitting, compared to intradiscal electrothermal therapy performed at one to two discs at a time, this approach may obviate the need for surgery and may reduce the duration of pain and disability incurred. However, the influence of multilevel intradiscal electrothermal therapy on long-term complications or outcome is not known. PMID:17444324

  17. High-efficiency joule-level Raman generation in Pb vapor

    SciTech Connect

    Brosnan, S.J.; Komine, H.; Stappaerts, E.A.; Plummer, M.J.; West, J.B.

    1982-04-01

    We have obtained nearly 1 J of blue-green radiation in 60-nsec pulses by Raman shifting an injection-locked XeCl laser Pb vapor. The measured 50% Raman energy conversion has been observed in both oscillator and oscillator-amplifier experiments. These results indicate that an XeCl/Pb blue-green laser efficiency of >1.4% should be possible.

  18. Electrothermal ring burn from a car battery.

    PubMed

    Sibley, Paul A; Godwin, Kenneth A

    2013-08-01

    Despite prevention efforts, burn injuries among auto mechanics are described in the literature. Electrothermal ring burns from car batteries occur by short-circuiting through the ring when it touches the open terminal or metal housing. This article describes a 34-year-old male auto mechanic who was holding a wrench when his gold ring touched the positive terminal of a 12-volt car battery and the wrench touched both his ring and the negative terminal. He felt instant pain and had a deep partial-thickness circumferential burn at the base of his ring finger. No other soft tissues were injured. He was initially managed conservatively, but after minimal healing at 3 weeks, he underwent a full-thickness skin graft. The graft incorporated well and healed by 4 weeks postoperatively. He had full range of motion. The cause of ring burns has been controversial, but based on reports similar to the current patient's mechanism, they are most likely electrothermal burns. Gold, a metal with high thermal conductivity, can heat up to its melting point in a matter of seconds. Many treatments have been described, including local wound care to split- and full-thickness skin grafts. Because most burns are preventable, staff should be warned and trained about the potential risks of contact burns. All jewelry should be removed, and the live battery terminal should be covered while working in the vicinity of the battery. PMID:23937760

  19. Benefits of Low-Power Electrothermal Propulsion

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; Sankovic, John M.

    1997-01-01

    Mission analyses were completed to show the benefits of low-power electrothermal propulsion systems for three classes'of LEO smallsat missions. Three different electrothermal systems were considered: (1) a 40 W ammonia resistojet system, (2) a 600 W hydrazine arcjet system, and (3) a 300 W ammonia resistojet. The benefits of using two 40 W ammonia resistojet systems were analyzed for three months of drag makeup of a Shuttle-launched 100 kg spacecraft in a 297 km orbit. The two 46 W resistojets decreased the propulsion system wet mass by 50% when compared to state-of-art hydrazine monopropellant thrusters. The 600 W arcjet system was used for a 300 km sun synchronous makeup mission of a 1000 kg satellite and was found to decrease the wet propulsion mass by 30%. Finally, the 300 W arcjet system was used on a 200 kg Earth-orbiting spacecraft for both orbit transfer from 300 to 400 km, two years of drag makeup, and a final orbit rise to 700 km. The arcjet system was determined to halve the propulsion system wet mass required for that scenario as compared to hydrazine monopropellant thrusters.

  20. Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma

    SciTech Connect

    Okada, H.; Kato, M.; Ishimaru, T.; Sekiguchi, H.; Wakahara, A.; Furukawa, M.

    2014-02-20

    Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma is investigated. Feasibility of precursors of triethylsilane (TES) and bis(dimethylamino)dimethylsilane (BDMADMS) is discussed based on a calculation of bond energies by computer simulation. Refractive indices of 1.81 and 1.71 are obtained for deposited films with TES and BDMADMS, respectively. X-ray photoelectron spectroscopy (XPS) analysis of the deposited film revealed that TES-based film coincides with the stoichiometric thermal silicon nitride.

  1. Optical rotation in excess of 100 rad generated by Rb vapor in a multipass cell

    SciTech Connect

    Li, S.; Vachaspati, P.; Sheng, D.; Dural, N.; Romalis, M. V.

    2011-12-15

    Paramagnetic Faraday rotation is a powerful technique for atom sensing widely used in quantum nondemolition measurements, fundamental symmetry tests, and other precision measurements. We demonstrate the use of a multipass optical cell for Faraday rotation spectroscopy and observe polarization rotation in excess of 100 rad from spin-polarized Rb vapor. Unlike optical cavities, multipass cells have a deterministic number of light passes and can be used to measure large optical rotations. We also observe a tenfold suppression of transverse spin relaxation when Rb atoms are placed in a coherent superposition state immune to spin-exchange collisions.

  2. Optical rotation in excess of 100 rad generated by Rb vapor in a multipass cell

    NASA Astrophysics Data System (ADS)

    Li, S.; Vachaspati, P.; Sheng, D.; Dural, N.; Romalis, M. V.

    2011-12-01

    Paramagnetic Faraday rotation is a powerful technique for atom sensing widely used in quantum nondemolition measurements, fundamental symmetry tests, and other precision measurements. We demonstrate the use of a multipass optical cell for Faraday rotation spectroscopy and observe polarization rotation in excess of 100 rad from spin-polarized Rb vapor. Unlike optical cavities, multipass cells have a deterministic number of light passes and can be used to measure large optical rotations. We also observe a tenfold suppression of transverse spin relaxation when Rb atoms are placed in a coherent superposition state immune to spin-exchange collisions.

  3. Electrothermal propulsion of spacecraft with millimeter and submillimeter electromagnetic energy

    NASA Technical Reports Server (NTRS)

    Frasch, L. L.; Fritz, R.; Asmussen, J.

    1988-01-01

    The concept of millimeter and submillimeter wave electrothermal propulsion is considered. State-of-the-art radiation sources from 30-1000 GHz are examined to determine their applicability to electrothermal propulsion systems. The problem of energy conversion and power conditioning in this frequency range is also addressed. The potential advantage of utilizing power beaming with millimeter and submillimeter systems is examined. Finally, areas of future research and development are indicated.

  4. Evaluation of Five Phase Digitally Controlled Rotating Field Plasma Source for Photochemical Mercury Vapor Generation Optical Emission Spectrometry.

    PubMed

    Matusiewicz, Henryk; Ślachciński, Mariusz; Pawłowski, Paweł; Portalski, Marek

    2015-01-01

    A new sensitive method for total mercury determination in reference materials using a 5-phase digitally controlled rotating field plasma source (RFP) for optical emission spectrometry (OES) was developed. A novel synergic effect of ultrasonic nebulization (USN) and ultraviolet-visible light (UV-Vis) irradiation when used in combination was exploited for efficient Hg vapor generation. UV- and Vis-based irradiation systems were studied. It was found that the most advantageous design was an ultrasonic nebulizer fitted with a 6 W mercury lamp supplying a microliter sample to a quartz oscillator, converting liquid into aerosol at the entrance of the UV spray chamber. Optimal conditions involved using a 20% v/v solution of acetic acid as the generation medium. The mercury cold vapor, favorably generated from Hg(2+) solutions by UV irradiation, was rapidly transported into a plasma source with rotating field generated within the five electrodes and detected by digitally controlled rotating field plasma optical emission spectrometry (RFP-OES). Under optimal conditions, the experimental concentration detection limit for the determination, calculated as the concentration giving a signal equal to three times the standard deviation of the blank (LOD, 3σblank criterion, peak height), was 4.1 ng mL(-1). The relative standard deviation for samples was equal to or better than 5% for liquid analysis and microsampling capability. The methodology was validated through determination of mercury in three certified reference materials (corresponding to biological and environmental samples) (NRCC DOLT-2, NRCC PACS-1, NIST 2710) using the external aqueous standard calibration techniques in acetic acid media, with satisfactory recoveries. Mercury serves as an example element to validate the capability of this approach. This is a simple, reagent-saving, cost-effective and green analytical method for mercury determination. PMID:26460362

  5. AC Electrothermal Circulatory Pumping Chip for Cell Culture.

    PubMed

    Lang, Qi; Wu, Yanshuang; Ren, Yukun; Tao, Ye; Lei, Lei; Jiang, Hongyuan

    2015-12-01

    Herein we describe a novel AC electrothermal (ACET) fluidic circulatory pumping chip to overcome the challenge of fluid-to-tissue ratio for "human-on-a-chip" cell culture systems. To avoid the deleterious effects of Joule heating and electric current on sample cells, a rectangular microchannel was designed with distantly separated regions for pumping and cell culture. Temperature variations were examined using a commercial thermocouple sensor to detect temperature values in both pumping and culture regions. To generate a sufficient ACET circulatory pumping rate, 30 pairs of asymmetrical electrodes were employed in the pumping region; generated ACET velocity was measured by fluorescent microparticle image velocimetry. The benefits of our pumping chip were demonstrated by culturing human embryonic kidney cells (HEK293T) and human colon carcinoma cells (SW620) for 72 h with an energized voltage of 3 V and 10 MHz. Cells grew and proliferated well, implying our ACET circulatory pumping chip has great potential for cell culture and tissue engineering applications. PMID:26558750

  6. Electrothermal modeling of silicon PCR chips

    NASA Astrophysics Data System (ADS)

    Cui, Zheng; Zhao, Zhan; Xia, Shanhong

    2001-04-01

    Polymerase chain reaction (PCR) on a microchip has drawn considerable attention in recent years. Although a microchip can have must fast heating and cooling rate, the delicacy in its structure makes the PCR experiment difficult and cracks often occurs particularly for the thin membrane type of PCR chips. Electrothermal modeling of PCR chips is presented using commercial MEMS software tool IntelliSuiteTM, with the aim of identifying the problems encountered in experiment and finding an optimum chip structure. Heating characteristics of four different heater designs have been compared, so have the PCR chambers with fixed frame and with suspended frame. The thermal stress analysis has shown that the structure and heater design can make significant difference in heating characteristics and in reducing the failure of PCR chips. The computer simulation has confirmed what has been found in experiment the reason of membrane cracks. Improvement in PCR chip design has been proposed.

  7. Electrothermal MEMS fiber scanner for optical endomicroscopy.

    PubMed

    Seo, Yeong-Hyeon; Hwang, Kyungmin; Park, Hyeon-Cheol; Jeong, Ki-Hun

    2016-02-22

    We report a novel MEMS fiber scanner with an electrothermal silicon microactuator and a directly mounted optical fiber. The microactuator comprises double hot arm and cold arm structures with a linking bridge and an optical fiber is aligned along a silicon fiber groove. The unique feature induces separation of resonant scanning frequencies of a single optical fiber in lateral and vertical directions, which realizes Lissajous scanning during the resonant motion. The footprint dimension of microactuator is 1.28 x 7 x 0.44 mm3. The resonant scanning frequencies of a 20 mm long optical fiber are 239.4 Hz and 218.4 Hz in lateral and vertical directions, respectively. The full scanned area indicates 451 μm x 558 μm under a 16 Vpp pulse train. This novel laser scanner can provide many opportunities for laser scanning endomicroscopic applications. PMID:26907043

  8. Study of monopropellants for electrothermal thrusters

    NASA Technical Reports Server (NTRS)

    Kuenzly, J. D.

    1974-01-01

    A 333 mN electrothermal thruster designed to use MIL-grade hydrazine was demonstrated to be suitable for operation with low freezing point monopropellants containing hydrazine azide, monomethylhydrazine, unsymmetrical-dimethylhydrazine and ammonia. The steady-state specific impulse was greater than 200 sec for all propellants. The pulsed-mode specific impulse for an azide blend exceeded 175 sec for pulse widths greater than 50 msec; propellants containing carbonaceous species delivered 175 sec pulsed-mode specific impulses for pulse widths greater than 100 msec. Longer thrust chamber residence times were required for the carbonaceous propellants; the original thruster design was modified by increasing the characteristic chamber length and screen packing density. Specific recommendations were made for the work required to design and develop flight worthy thrusters, including methods to increase propellant dispersal at injection, thruster geometry changes to reduce holding power levels and methods to initiate the rapid decomposition of the carbonaceous propellants.

  9. Experiments on a repetitively pulsed electrothermal thruster

    NASA Technical Reports Server (NTRS)

    Burton, R. L.; Fleischer, D.; Goldstein, S. A.; Tidman, D. A.

    1987-01-01

    This paper presents experimental results from an investigation of a pulsed electrothermal (PET) thruster using water propellant. The PET thruster is operated on a calibrated thrust stand, and produces a thrust to power ratio of T/P = 0.07 + or - 0.01 N/kW. The discharge conditions are inferred from a numerical model which predicts pressure and temperature levels of 300-500 atm and 20,000 K, respectively. These values in turn correctly predict the measured values of impulse bit and discharge resistance. The inferred ideal exhaust velocity from these conditions is 17 km/sec, but the injection of water propellant produces a test tank background pressure of 10-20 Torr, which reduces the exhaust velocity to 14 km/sec. This value corresponds to a thrust efficiency of 54 + or - 7 percent when all experimental errors are taken into account.

  10. Ultrasound-promoted cold vapor generation in the presence of formic acid for determination of mercury by atomic absorption spectrometry.

    PubMed

    Gil, Sandra; Lavilla, Isela; Bendicho, Carlos

    2006-09-01

    A new cold vapor technique within the context of green chemistry is described for determination of mercury in liquid samples following high-intensity ultrasonication. Volatile Hg evolved in a sonoreactor without the use of a chemical reducing agent is carried to a quartz cell kept at room temperature for measurement of the atomic absorption. The mechanism involved lies in the reduction of Hg(II) to Hg(0) by reducing gases formed upon sonication and subsequent volatilization of Hg(0) due to the degassing effect caused by the cavitation phenomenon. Addition of a low molecular weight organic acid such as formic acid favors the process, but vapor generation also occurs from Hg solutions in ultrapure water. The detection limit of Hg was 0.1 microg/L, and the repeatability, expressed as relative standard deviation, was 4.4% (peak height). Addition of small amounts of oxidizing substances such as the permanganate or dichromate anions completely suppressed the formation of Hg(0), which confirms the above mechanism. Effect of other factors such as ultrasound irradiation time, ultrasound amplitude, and the presence of concomitants are also investigated. Some complexing anions such as chloride favored the stabilization of Hg(II) in solution, hence causing an interference effect on the ultrasound-assisted reduction/volatilization process. PMID:16944910

  11. Transition-edge sensor with enhanced electrothermal feedback for cryogenic particle detection

    DOEpatents

    Nam, Sae Woo; Cabrera, Blas

    2001-01-01

    A superconducting transition-edge sensor with an electrothermal-feedback circuit, a heat sink thermally coupled thereto, a bias-feedback circuit electrically coupled with the electrothermal feedback circuit, and a current sensor electrically coupled with the bias-feedback circuit and inductively coupled with the electrothermal-feedback circuit.

  12. Modeling the capillary discharge of an electrothermal (ET) launcher

    NASA Astrophysics Data System (ADS)

    Least, Travis

    Over the past few decades, different branches of the US Department of Defense (DoD) have invested at improving the field ability of electromagnetic launchers. One such focus has been on achieving hypervelocity launch velocities in excess of 7 km/s for direct launch to space applications [1]. It has been shown that pre-injection is required for this to be achieved. One method of pre-injection which has promise involves using an electro-thermal (ET) due to its ability to achieve the desired velocities with a minimal amount of hot plasma injected into the launcher behind the projectile. Despite the demonstration of pre-injection using this method, polymer ablation is not very well known and this makes it challenging to predict how the system will behave for a given input of electrical power. In this work, the rate of ablation has been studied and predicted using different models to generate the best possible characteristic curve. [1] - Wetz, David A., Francis Stefani, Jerald V. Parker, and Ian R. McNab. "Advancements in the Development of a Plasma-Driven Electromagnetic Launcher." IEEE TRANSACTIONS ON MAGNETICS 45.1 (2009): 495--500. IEEE Xplore. Web. 18 Aug. 2012.

  13. Determination of inorganic and total mercury by vapor generation atomic absorption spectrometry using different temperatures of the measurement cell

    NASA Astrophysics Data System (ADS)

    Kaercher, Luiz Eduardo; Goldschmidt, Fabiane; Paniz, José Neri Gottfried; de Moraes Flores, Érico Marlon; Dressler, Valderi Luiz

    2005-06-01

    A simple and inexpensive laboratory-built flow injection vapor generation system coupled to atomic absorption spectrometry (FI-VG AAS) for inorganic and total mercury determination has been developed. It is based on the vapor generation of total mercury and a selective detection of Hg 2 + or total mercury by varying the temperature of the measurement cell. Only the inorganic mercury is measured when the quartz cell is at room temperature, and when the cell is heated to 650 °C or higher the total Hg concentration is measured. The organic Hg concentration in the sample is calculated from the difference between the total Hg and Hg 2 + concentrations. Parameters such as the type of acid (HCl or HNO 3) and its concentration, reductant (NaBH 4) concentration, carrier solution (HCl) flow rate, carrier gas flow rate, sample volume and quartz cell temperature, which influence FI-VG AAS system performance, were systematically investigated. The optimized conditions for Hg 2 + and total Hg determinations were: 1.0 mol l - 1 HCl as carrier solution, carrier flow rate of 3.5 ml min - 1 , 0.1% (m/v) NaBH 4, reductant flow rate of 1.0 ml min - 1 and carrier gas flow rate of 200 ml min - 1 . The relative standard deviation (RSD) is lower than 5.0% for a 1.0 μg l - 1 Hg solution and the limit of quantification (LOQ, 10 s) is 55 ng g - 1 . Certified samples of dogfish muscle (DORM-1 and DORM-2) and non-certified fish samples were analyzed, using a 6.0 mol l - 1 HCl solution for analyte extraction. The Hg 2 + and CH 3Hg + concentrations found were in agreement with certified ones.

  14. Simple field device for measurement of dimethyl sulfide and dimethylsulfoniopropionate in natural waters, based on vapor generation and chemiluminescence detection.

    PubMed

    Nagahata, Takanori; Kajiwara, Hidetaka; Ohira, Shin-Ichi; Toda, Kei

    2013-05-01

    A small, simple device was developed for trace analysis of dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP) in natural waters. These compounds are known to be the major sources of cloud condensation nuclei in the oceanic atmosphere and ideally should be measured onsite because of their volatility and instability. First, chemical and physical vapor generations were examined, and simple pressurizing by injection of 30 mL of air using a syringe was adopted. Pressurized headspace air above a 10 mL water sample was introduced to a detection cell as a result of the pressure differential and mixed with ozone to induce chemiluminescence. Although the measurement procedure was simple, the method was very sensitive: sharp peaks appeared within seconds for nanomolar levels of DMS, and the limit of detection was 0.02 nmol L(-1) (1 ng L(-1)). Although interference from methanethiol was significant, this was successfully addressed by adding a small amount of Cd(2+) before DMS vapor generation. DMSP was also measured after hydrolysis to DMS, as previously reported. Pond water and seawater samples were analyzed, and DMS was found in both types of sample, whereas DMSP was observed only in seawater. The DMS/DMSP data obtained using the developed method were compared with data obtained by purge/trap and gas chromatography-mass spectrometry, and the data from the two methods agreed, with good correlation (R(2) = 0.9956). The developed device is inexpensive, light (5 kg), simple to use, can be applied in the field, and is sensitive enough for fresh- and seawater analysis. PMID:23551252

  15. Electrothermally driven high-frequency piezoresistive SiC cantilevers for dynamic atomic force microscopy

    SciTech Connect

    Boubekri, R.; Cambril, E.; Couraud, L.; Bernardi, L.; Madouri, A.; Portail, M.; Chassagne, T.; Moisson, C.; Zielinski, M.; Jiao, S.; Michaud, J.-F.; Alquier, D.; Bouloc, J.; Nony, L.; Bocquet, F.; Loppacher, C.

    2014-08-07

    Cantilevers with resonance frequency ranging from 1 MHz to 100 MHz have been developed for dynamic atomic force microscopy. These sensors are fabricated from 3C-SiC epilayers grown on Si(100) substrates by low pressure chemical vapor deposition. They use an on-chip method both for driving and sensing the displacement of the cantilever. A first gold metallic loop deposited on top of the cantilever is used to drive its oscillation by electrothermal actuation. The sensing of this oscillation is performed by monitoring the resistance of a second Au loop. This metallic piezoresistive detection method has distinct advantages relative to more common semiconductor-based schemes. The optimization, design, fabrication, and characteristics of these cantilevers are discussed.

  16. Metal carbonyl vapor generation coupled with dielectric barrier discharge to avoid plasma quench for optical emission spectrometry.

    PubMed

    Cai, Yi; Li, Shao-Hua; Dou, Shuai; Yu, Yong-Liang; Wang, Jian-Hua

    2015-01-20

    The scope of dielectric barrier discharge (DBD) microplasma as a radiation source for optical emission spectrometry (OES) is extended by nickel carbonyl vapor generation. We proved that metal carbonyl completely avoids the extinguishing of plasma, and it is much more suitable for matching the DBD excitation and OES detection with respect to significant DBD quenching by concomitant hydrogen when hydride generation is used. A concentric quartz UV reactor allows sample solution to flow through the central channel wherein to efficiently receive the uniformly distributed UV irradiation in the confined cylindrical space between the concentric tubes, which facilitates effective carbonyl generation in a nickel solution. The carbonyl is transferred into the DBD excitation chamber by an argon stream for nickel excitation, and the characteristic emission of nickel at 232.0 nm is detected by a charge-coupled device (CCD) spectrometer. A 1.0 mL sample solution results in a linear range of 5-100 μg L(-1) along with a detection limit of 1.3 μg L(-1) and a precision of 2.4% RSD at 50 μg L(-1). The present DBD-OES system is validated by nickel in certified reference materials. PMID:25511607

  17. Particle generators for the calibration and testing of narcotic and explosive vapor/particle detection systems

    NASA Astrophysics Data System (ADS)

    Davies, John P.; Hallowell, Susan F.; Hoglund, David E.

    1994-03-01

    A review of data on narcotics and explosives particulates is presented. Methods to generate particles of narcotics and explosives will be discussed with respect to resulting particle size distribution and mass output. The application of these standards to the testing of narcotic and explosive particle detection systems will be addressed.

  18. Experimental Study of Electrothermal 3D Mixing using 3D microPIV

    NASA Astrophysics Data System (ADS)

    Kauffmann, Paul; Loire, Sophie; Meinhart, Carl; Mezic, Igor

    2012-11-01

    Mixing is a keystep which can greatly accelerate bio-reactions. For thirty years, dynamical system theory has predicted that chaotic mixing must involve at least 3 dimensions (either time dependent 2D flows or 3D flows). So far, 3D embedded chaotic mixing has been scarcely studied at microscale. In that regard, electrokinetics has emerged as an efficient embedded actuation to drive microflows. Physiological mediums can be driven by electrothermal flows generated by the interaction of an electric field with conductivity and permittivity gradients induced by Joule heating We present original electrothermal time dependant 3D (3D+1) mixing in microwells. The key point of our chaotic mixer is to generate overlapping asymmetric vortices, which switch periodically. When the two vortex configurations blink, flows stretch and fold, thereby generating chaotic advection. Each flow configuration is characterized by an original 3D PIV (3 Components / 3 Dimensions) based on the decomposition of the flows by Proper Orthogonal Decomposition. Velocity field distribution are then compared to COMSOL simulation and discussed. Mixing efficiency of low diffusive particles is studied using the mix-variance coefficient and shows a dramatic increase of mixing efficiency compared to steady flow.

  19. Investigation of a pulsed electrothermal thruster system

    NASA Technical Reports Server (NTRS)

    Burton, R. L.; Goldstein, S. A.; Hilko, B. K.; Tidman, D. A.; Winsor, N. K.

    1984-01-01

    The performance of an ablative wall Pulsed Electrothermal (PET) thruster is accurately characterized on a calibrated thrust stand, using polyethylene propellant. The thruster is tested for four configurations of capillary length and pulse length. The exhaust velocity is determined with twin time-of-flight photodiode stagnation probes, and the ablated mass is measured from the loss over ten shots. Based on the measured thrust impulse and the ablated mass, the specific impulse varies from 1000 to 1750 seconds. The thrust to power varies from .05 N/kW (quasi-steady mode) to .10 N/kW (unsteady mode). The thruster efficiency varies from .56 at 1000 seconds to .42 at 1750 seconds. A conceptual design is presented for a 40 kW PET propulsion system. The point design system performance is .62 system efficiency at 1000 seconds specific impulse. The system's reliability is enhanced by incorporating 20, 20 kW thruster modules which are fired in pairs. The thruster design is non-ablative, and uses water propellant, from a central storage tank, injected through the cathode.

  20. Investigation of a pulsed electrothermal thruster

    NASA Technical Reports Server (NTRS)

    Burton, R. L.; Goldstein, S. A.; Hilko, B. K.; Tidman, D. A.; Winsor, N. K.

    1983-01-01

    Exhaust velocity and thrust measurements are performed on a pulsed electrothermal thruster using polyethylene and Teflon propellants. The results verify theoretical predictions of equilibrium flow in the nozzle, resulting in substantial recovery of the energy of dissociation and ionization. The thruster is tested in an unsteady mode (15 micro sec current pulse and 15 cm discharge length) and in a quasi-steady mode (48 micro sec current pulse and 5 cm discharge length). All tests are run at 2 kJ. The exhaust velocity of the propellant mass exiting during the current pulse is measured with two types of time of flight probes, and the impulse bit is measured on a thrust stand. It is inferred from both theory and experiment that an additional amount of mass is exhausted after the pulse. The measured thrust to power ratio for polyethylene is T/P = 0.10 NkW at 21 km/sec in the unsteady mode, and T/P = .053 N/kW at 27 km/sec in the quasi-steady mode, where the velocities are measured by the time-of-flight probes. For Teflon propellant, T/P = .20 N/kW at 15 km/sec (unsteady mode) and 0.090 N/kW at 20 km/sec (quasi-steady mode). The discharge pressure and temperature predicted by a computational model for polyethylene are consistent with the measured thrust and discharge resistance.

  1. Detection of bromine by ICP-oa-ToF-MS following photochemical vapor generation.

    PubMed

    Sturgeon, Ralph E

    2015-03-01

    A unique flow-through photochemical reactor is utilized for the generation of volatile methyl bromide from aqueous solutions of bromide and bromate ions in a medium of 2% acetic acid containing 3000 μg/mL NH4Cl. The volatile product is transported to a thin-film gas-liquid phase separator and directed to an inductively coupled plasma (ICP) tine-of-flight mass spectrometer for detection and quantitation using either of the (79)Br or (81)Br isotopes. Utilizing a sample flow rate of 3.3 mL/min and a 13 s irradiation time, a detection limit of 0.14 ng/mL is achieved, yielding a 17-fold enhancement over conventional solution nebulization. The estimated generation efficiency of 95% provides for a significant increase in analyte transport efficiency to the ICP. Precision of replicate measurement is 2.5% (RSD) at 20 ng/mL. The methodology was validated by successful determination of bromine in reference materials, including IRMM (BCR-611) low level bromide in groundwater, NIST SRM 1568b Rice Flour, and SRM 1632 bituminous coal. PMID:25649253

  2. Mechanisms of chemical vapor generation by aqueous tetrahydridoborate. Recent developments toward the definition of a more general reaction model

    NASA Astrophysics Data System (ADS)

    D'Ulivo, Alessandro

    2016-05-01

    A reaction model describing the reactivity of metal and semimetal species with aqueous tetrahydridoborate (THB) has been drawn taking into account the mechanism of chemical vapor generation (CVG) of hydrides, recent evidences on the mechanism of interference and formation of byproducts in arsane generation, and other evidences in the field of the synthesis of nanoparticles and catalytic hydrolysis of THB by metal nanoparticles. The new "non-analytical" reaction model is of more general validity than the previously described "analytical" reaction model for CVG. The non-analytical model is valid for reaction of a single analyte with THB and for conditions approaching those typically encountered in the synthesis of nanoparticles and macroprecipitates. It reduces to the previously proposed analytical model under conditions typically employed in CVG for trace analysis (analyte below the μM level, borane/analyte ≫ 103 mol/mol, no interference). The non-analytical reaction model is not able to explain all the interference effects observed in CVG, which can be achieved only by assuming the interaction among the species of reaction pathways of different analytical substrates. The reunification of CVG, the synthesis of nanoparticles by aqueous THB and the catalytic hydrolysis of THB inside a common frame contribute to rationalization of the complex reactivity of aqueous THB with metal and semimetal species.

  3. Design and characterization of a microelectromechanical system electro-thermal linear motor with interlock mechanism for micro manipulators.

    PubMed

    Hu, Tengjiang; Zhao, Yulong; Li, Xiuyuan; Zhao, You; Bai, Yingwei

    2016-03-01

    The design, fabrication, and testing of a novel electro-thermal linear motor for micro manipulators is presented in this paper. The V-shape electro-thermal actuator arrays, micro lever, micro spring, and slider are introduced. In moving operation, the linear motor can move nearly 1 mm displacement with 100 μm each step while keeping the applied voltage as low as 17 V. In holding operation, the motor can stay in one particular position without consuming energy and no creep deformation is found. Actuation force of 12.7 mN indicates the high force generation capability of the device. Experiments of lifetime show that the device can wear over two million cycles of operation. A silicon-on-insulator wafer is introduced to fabricate a high aspect ratio structure and the chip size is 8.5 mm × 8.5 mm × 0.5 mm. PMID:27036807

  4. Design and characterization of a microelectromechanical system electro-thermal linear motor with interlock mechanism for micro manipulators

    NASA Astrophysics Data System (ADS)

    Hu, Tengjiang; Zhao, Yulong; Li, Xiuyuan; Zhao, You; Bai, Yingwei

    2016-03-01

    The design, fabrication, and testing of a novel electro-thermal linear motor for micro manipulators is presented in this paper. The V-shape electro-thermal actuator arrays, micro lever, micro spring, and slider are introduced. In moving operation, the linear motor can move nearly 1 mm displacement with 100 μm each step while keeping the applied voltage as low as 17 V. In holding operation, the motor can stay in one particular position without consuming energy and no creep deformation is found. Actuation force of 12.7 mN indicates the high force generation capability of the device. Experiments of lifetime show that the device can wear over two million cycles of operation. A silicon-on-insulator wafer is introduced to fabricate a high aspect ratio structure and the chip size is 8.5 mm × 8.5 mm × 0.5 mm.

  5. Study of monopropellants for electrothermal thrusters: Analytical task summary report

    NASA Technical Reports Server (NTRS)

    Kuenzly, J. D.; Grabbi, R.

    1973-01-01

    The feasibility of operating small thrust level electrothermal thrusters is determined with monopropellants other than MIL-grade hydrazine. The work scope includes analytical study, design and fabrication of demonstration thrusters, and an evaluation test program where monopropellants with freezing points lower than MIL-grade hydrazine are evaluated and characterized to determine their applicability to electrothermal thrusters for spacecraft attitude control. Results of propellant chemistry studies and performance analyses indicated that the most promising candidate monopropellants to be investigated are monomethylhydrazine, Aerozine-50, 77% hydrazine-23% hydrazine azide blend, and TRW formulated mixed hydrazine monopropellant (MHM) consisting of 35% hydrazine-50% monomethylhydrazine-15% ammonia.

  6. Development of Liquid-Vapor Core Reactors with MHD Generator for Space Power and Propulsion Applications

    SciTech Connect

    Samim Anghaie

    2002-08-13

    Any reactor that utilizes fuel consisting of a fissile material in a gaseous state may be referred to as a gaseous core reactor (GCR). Studies on GCRs have primarily been limited to the conceptual phase, mostly due to budget cuts and program cancellations in the early 1970's. A few scientific experiments have been conducted on candidate concepts, primarily of static pressure fissile gas filling a cylindrical or spherical cavity surrounded by a moderating shell, such as beryllium, heavy water, or graphite. The main interest in this area of nuclear power generation is for space applications. The interest in space applications has developed due to the promise of significant enhancement in fuel utilization, safety, plant efficiency, special high-performance features, load-following capabilities, power conversion optimization, and other key aspects of nuclear power generation. The design of a successful GCR adapted for use in space is complicated. The fissile material studied in the pa st has been in a fluorine compound, either a tetrafluoride or a hexafluoride. Both of these molecules have an impact on the structural material used in the making of a GCR. Uranium hexafluoride as a fuel allows for a lower operating temperature, but at temperatures greater than 900K becomes essentially impossible to contain. This difficulty with the use of UF6 has caused engineers and scientists to use uranium tetrafluoride, which is a more stable molecule but has the disadvantage of requiring significantly higher operating temperatures. Gas core reactors have traditionally been studied in a steady state configuration. In this manner a fissile gas and working fluid are introduced into the core, called a cavity, that is surrounded by a reflector constructed of materials such as Be or BeO. These reactors have often been described as cavity reactors because the density of the fissile gas is low and criticality is achieved only by means of the reflector to reduce neutron leakage from the core

  7. Aerosol generation and charging phenomena in plasma- enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Forsyth, Bruce Riley

    This thesis is concerned with advancing the theoretical study of the origin and acquisition of particle charge from aerosol generation. A newly designed integral mobility charge analyzer was constructed and calibrated to measure the electrical charge distribution on aerosol particles between 10 nanometer (nm) and 10 micrometer ( m m). The charge analyzer can be used in a wide variety of laboratory and industrial applications due to its broad operating range. Initially, the analyzer performance was tested by generating a variety of aerosol particles with and without neutralization by two different radioactive sources. As a result, experimental charge distributions can be compared with analytical and numerical models of spray and contact electrification related to the interface's double layer. The liquid surface can be simply modeled as a flat plate electrical capacitor with a stored dipole charge layer near the interface. Experimental research will investigate the charge state of a surface double layer using the interaction of dissolved particles. Ion interactions with a particle- liquid interface in the electrical double layer can be analyzed by measuring the aerosol charge distribution from different concentrations of salts, colloids and organic solutions. However, the main thesis research goal is to monitor charged contaminants in process exhaust using the developed integral mobility charge analyzer. Experimental measurements can then be correlated with the dynamic behavior of different nucleated species in the reactor. Hypothetically, particles formed in the plasma volume will have a different charge and size distribution than exhaust line particles originating from unreacted gas species in the pump line. A thorough understanding of the charge level of particles within the plasma volume is necessary to understand the charging, trapping and behavior of contaminant species in the CVD film processes. Charge neutralization by free ion attachment in the exhaust lines

  8. Second-Harmonic Generation and Relaxation in Polyurea Thin Films Prepared by Vapor Deposition Polymerization

    NASA Astrophysics Data System (ADS)

    Hikita, Masayuki; Yamada, Sinichi; Mizutani, Teruyosi

    1993-06-01

    Aromatic polyurea thin (PU) films were fabricated by means of coevaporation of 4,4'-diphenylmethane diisocyanate (MDI) and either 4,4'-diamino diphenyl methane (DDM) or 4,4'-diamino diphenyl ether (DDE). For the two PU films, second-harmonic generation (SHG) caused by corona poling and the subsequent isothermal decay were investigated. The second-order nonlinear coefficient d33 was estimated to be 5.3 and 6.3 pm/V for PU(DDM) and PU(DDE), respectively, and proved to exhibit almost no decay with time up to 2000 h. It was also found that annealing prior to the poling process caused no additional increase of SHG. This result was interpreted in terms of increase in the packing density of molecules, leading to suppression of the molecular orientation. PU films containing excess residual isocyanate groups showed a large SHG decay to about 60% of the initial value within 10 min. It was concluded that the residual isocyanate groups in as-deposited PU films greatly affects the behavior of SHG relaxation.

  9. Direct determination of mercury in white vinegar by matrix assisted photochemical vapor generation atomic fluorescence spectrometry detection

    NASA Astrophysics Data System (ADS)

    Liu, Qingyang

    2010-07-01

    This paper proposes the use of photochemical vapor generation with acetic acid as sample introduction for the direct determination of ultra-trace mercury in white vinegars by atomic fluorescence spectrometry. Under ultraviolet irradiation, the sample matrix (acetic acid) can reduce mercury ion to atomic mercury Hg 0, which is swept by argon gas into an atomic fluorescence spectrometer for subsequent analytical measurements. The effects of several factors such as the concentration of acetic acid, irradiation time, the flow rate of the carrier gas and matrix effects were discussed and optimized to give detection limits of 0.08 ng mL -1 for mercury. Using the experimental conditions established during the optimization (3% v/v acetic acid, 30 s irradiation time and 20 W mercury lamp), the precision levels, expressed as relative standard deviation, were 4.6% (one day) and 7.8% (inter-day) for mercury ( n = 9). Addition/recovery tests for evaluation of the accuracy were in the range of 92-98% for mercury. The method was also validated by analysis of vinegar samples without detectable amount of Hg spiked with aqueous standard reference materials (GBW(E) 080392 and GBW(E) 080393). The results were also compared with those obtained by acid digestion procedure and determination of mercury by ICP-MS. There was no significant difference between the results obtained by the two methods based on a t-test (at 95% confidence level).

  10. Ultra-trace determination of methylmercuy in seafood by atomic fluorescence spectrometry coupled with electrochemical cold vapor generation.

    PubMed

    Zu, Wenchuan; Wang, Zhenghao

    2016-03-01

    A homemade electrochemical flow cell was adopted for the determination of methylmercury. The cold vapor of mercury atoms was generated from the surface of glassycarbon cathode through the method of electrolytic reduction and detected by atomic fluorescence spectroscopy subsequently. The operating conditions were optimized with 2 ng mL(-1) methylmercury standard solution. The caliberation curve was favorably linear when the concentrations of standard HgCH3(+) solutions were in the range of 0.2-5 ng mL(-1)(as Hg). Under the optimized conditions, the limit of detection (LOD) for methylmercury was 1.88×10(-3)ng mL(-1) and the precision evaluated by relative standard deviation was 2.0% for six times 2 ng mL(-1) standard solution replicates. The terminal analytical results of seafood samples, available from local market, showed that the methylmercury content ranged within 3.7-45.8 ng g(-1). The recoveries for methylmercury spiked samples were found to be in the range of 87.6-103.6% and the relative standard deviations below 5% (n=6) were acquired, which showed this method was feasible for real sample analysis. PMID:26615576

  11. Design, Modeling, Fabrication, and Evaluation of Thermoelectric Generators with Hot-Wire Chemical Vapor Deposited Polysilicon as Thermoelement Material

    NASA Astrophysics Data System (ADS)

    de Leon, Maria Theresa; Tarazona, Antulio; Chong, Harold; Kraft, Michael

    2014-11-01

    This paper presents the design, modeling, fabrication, and evaluation of thermoelectric generators (TEGs) with p-type polysilicon deposited by hot-wire chemical vapor deposition (HWCVD) as thermoelement material. A thermal model is developed based on energy balance and heat transfer equations using lumped thermal conductances. Several test structures were fabricated to allow characterization of the boron-doped polysilicon material deposited by HWCVD. The film was found to be electrically active without any post-deposition annealing. Based on the tests performed on the test structures, it is determined that the Seebeck coefficient, thermal conductivity, and electrical resistivity of the HWCVD polysilicon are 113 μV/K, 126 W/mK, and 3.58 × 10-5 Ω m, respectively. Results from laser tests performed on the fabricated TEG are in good agreement with the thermal model. The temperature values derived from the thermal model are within 2.8% of the measured temperature values. For a 1-W laser input, an open-circuit voltage and output power of 247 mV and 347 nW, respectively, were generated. This translates to a temperature difference of 63°C across the thermoelements. This paper demonstrates that HWCVD, which is a cost-effective way of producing solar cells, can also be applied in the production of TEGs. By establishing that HWCVD polysilicon can be an effective thermoelectric material, further work on developing photovoltaic-thermoelectric (PV-TE) hybrid microsystems that are cost-effective and better performing can be explored.

  12. Theoretical and experimental characterization of the in-plane tip force and deflection achieved with asymmetrical polysilicon electrothermal microactuators

    NASA Astrophysics Data System (ADS)

    Allen, Peter B.; Boydston, Noah C.; Howard, Jeffrey T.; Ko, Simon Y.; Kolesar, Edward S., Jr.; Ruff, Matthew D.; Wilken, Josh M.; Wilks, Richard J.

    2000-08-01

    Several microactuator technologies have recently been investigated for positioning individual elements in large-scale microelectromechanical systems (MEMS). Electrostatic, magnetostatic, piezoelectric and thermal expansion are the most common modes of microactuator operation. This research focuses on the design and experimental characterization of two types of asymmetrical MEMS electrothermal microactuators. The motivation is to present a unified description of the behavior of the electrothermal microactuator so that it can be adapted to a variety of MEMS applications. Both MEMS polysilicon electrothermal microactuator design variants use resistive (Joule) heating to generate thermal expansion and movement. In a conventional electrothermal microactuator, the hot arm is positioned parallel to a cold arm, but because the hot arm is narrower than the cold arm, the electrical resistance of the hot arm is higher. When an electric curren passes through the microactuator (through the series connected electrical resistance of the hot and cold arms), the hot arm is heated to a higher temperature than the cold arm. This temperature increase causes the hot arm to expand along its length, thus forcing the tip of the device to rotate about a mechanical flexure element. The new thermal actuator design eliminates the parasitic electrical resistance of the cold arm by incorporating an additional hot arm. The second hot arm results in an improvement in electrical efficiency by providing an active return current path. Additionally, the rotating cold arm can have a narrower flexure than the flexure in a conventional single-hot arm device because it does not have to pass an electric current. The narrower flexure element results in an improvement in mechanical efficiency. Deflection and force measurements of both actuators as a function of applied electrical power are presented.

  13. The annular flow electrothermal ramjet. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Shaw, B. D.

    1984-01-01

    The annular flow, electrothermal, plug ramjet is examined as a possible means of achieving rapid projectile acceleration to velocities for such applications as direct launch of spacebound payloads. The performance of this ramjet operating with hydrogen propellant is examined for cases where this working fluid is treated: (1) as a perfect gas, and (2) as a gas that is allowed to dissociate and ionize and then recombine with finite reaction rates in the nozzle. Performance results for these cases are compared to the performance of a conventional ramjet operating with perfect gas hydrogen propellant. The performance of the conventional ramjet is superior to that of the annular flow, electrothermal ramjet. However, it is argued that the mechanical complexities associated with conventional ramjet operation are difficult to attain, and for this reason the annular flow, electrothermal ramjet is more desirable as a launch system. Models are presented which describe both electrothermal plug ramjet and conventional ramjet operation, and it is shown that for a given flight velocity there is a rate of heat addition per unit propellant mass for which ramjet operation is optimized.

  14. Morphological and spectroscopic investigation of the behavior of permanent iridium modifier deposited on pyrolytic graphite coated and zirconium treated platforms in electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Slaveykova, Vera I.; Lampugnani, Leonardo; Tsalev, Dimiter L.; Sabbatini, L.

    1997-12-01

    In order to better characterise a permanent modifier based on iridium deposited on zirconium or tungsten treated platforms of transversely heated graphite atomizer, and to gain additional information about its chemical behavior directed to an eventual further optimization, a series of experiments were carried out, both by surface techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS or ESCA) and X-ray fluorescence (XRF) and by electrothermal atomic absorption spectrometry on the iridium release from unmodified and various other modified pyrolytic graphite platforms. Special attention was paid to the influence of the amount of iridium, zirconium carbide coating of the platform surface and the presence of citric acid on the iridium vaporization during pyrolysis and atomization. The processes of iridium losses during pyrolysis and atomization and peak maximum alignment depend on the amount of the iridium deposited on the pyrolytic graphite coated platforms in the presence of nitric acid. A fractional order of release which suggests an atom vaporization from the surface or edges of the iridium islands was estimated. In the presence of citric acid, mass independence and zero order of the atom release were found. The zirconium treatment of the platform results in change of the spatial distribution of iridium and hence its vaporization. Vaporization temperatures as high as 2100°C, and first order of the process of atom generation were obtained. While it was possible to study the iridium atomization from uncoated and zirconium coated surfaces, evidencing a different order for the release process, the same was not possible for the tungsten coated platforms due to an 'overstabilization' that brought the iridium atomization temperature out of the working range of the instrument used. The different chemical behavior of tungsten and zirconium was also confirmed by XPS investigations. With tungsten, evidence of both WC and WO bonding

  15. Determination of copper in airborne particulate matter using slurry sampling and chemical vapor generation atomic absorption spectrometry.

    PubMed

    Silva, Laiana O B; Leao, Danilo J; dos Santos, Debora C; Matos, Geraldo D; de Andrade, Jailson B; Ferreira, Sergio L C

    2014-09-01

    The present paper describes the development of a method for the determination of copper in airborne particulate matter using slurry sampling and chemical vapor generation atomic absorption spectrometry (CVG AAS). Chemometric tools were employed to characterize the influence of several factors on the generation of volatile copper species. First, a two-level full factorial design was performed that included the following chemical variables: hydrochloric acid concentration, tetrahydroborate concentration, sulfanilamide concentration and tetrahydroborate volume, using absorbance as the response. Under the established experimental conditions, the hydrochloric acid concentration had the greatest influence on the generation of volatile copper species. Subsequently, a Box-Behnken design was performed to determine the optimum conditions for these parameters. A second chemometric study employing a two-level full factorial design was performed to evaluate the following physical factors: tetrahydroborate flow rate, flame composition, alcohol volume and sample volume. The results of this study demonstrated that the tetrahydroborate flow rate was critical for the process. The chemometric experiments determined the following experimental conditions for the method: hydrochloric acid concentration, 0.208 M; tetrahydroborate concentration, 4.59%; sulfanilamide concentration, 0.79%; tetrahydroborate volume, 2.50 mL; tetrahydroborate flow rate, 6.50 mL min(-1); alcohol volume, 200 µL; and sample volume, 7.0 mL. Thus, this method, using a slurry volume of 500 µL and a final dilution of 7 mL, allowed for the determination of copper with limits of detection and quantification of 0.30 and 0.99 µg L(-1), respectively. Precisions, expressed as RSD%, of 4.6 and 2.8% were obtained using copper solutions at concentrations of 5.0 and 50.0 µg L(-1), respectively. The accuracy was evaluated by the analysis of a certified reference material of urban particulate matter. The copper concentration

  16. Single drop solution electrode glow discharge for plasma assisted-chemical vapor generation: sensitive detection of zinc and cadmium in limited amounts of samples.

    PubMed

    Li, Zhi-ang; Tan, Qing; Hou, Xiandeng; Xu, Kailai; Zheng, Chengbin

    2014-12-16

    A simple and sensitive approach is proposed and evaluated for determination of ultratrace Zn and Cd in limited amounts of samples or tens of cells based on a novel single drop (5-20 μL) solution electrode glow discharge assisted-chemical vapor generation technique. Volatile species of Zn and Cd were immediately generated and separated from the liquid phase for transporting to atomic fluorescence or atomic mass spectrometric detectors for their determination only using hydrogen when the glow discharge was ignited between the surface of a liquid drop and the tip of a tungsten electrode. Limits of detection are better than 0.01 μg L(-1) (0.2 pg) for Cd and 0.1 μg L(-1) (2 pg) for Zn, respectively, and comparable or better than the previously reported results due to only a 20 μL sampling volume required, which makes the proposed technique convenient for the determination of Zn and Cd in limited amounts of samples or even only tens of cells. The proposed method not only retains the advantages of conventional chemical vapor generation but also provides several unique advantages, including better sensitivity, lower sample and power consumption, higher chemical vapor generation efficiencies and simpler setup, as well as greener analytical chemistry. The utility of this technique was demonstrated by the determination of ultratrace Cd and Zn in several single human hair samples, Certified Reference Materials GBW07601a (human hair powder) and paramecium cells. PMID:25409265

  17. Efficient generation of 480 fs electrical pulses on transmission lines by photoconductive switching in metalorganic chemical vapor deposited CdTe

    NASA Astrophysics Data System (ADS)

    Nuss, Martin C.; Kisker, D. W.; Smith, P. R.; Harvey, T. E.

    1989-01-01

    Electrical pulses of only 480 fs duration have been generated by photoconductive switching in CdTe grown by ultraviolet-enhanced metalorganic chemical vapor deposition (MOCVD). In addition to the extremely fast switching times, MOCVD CdTe also exhibits a high mobility of 180 sq cm/V s and can be grown on almost any substrate, making it ideal for integration into existing circuits and devices.

  18. Direct measurement of axial momentum imparted by an electrothermal radiofrequency plasma micro-thruster

    NASA Astrophysics Data System (ADS)

    Charles, Christine; Boswell, Roderick; Bish, Andrew; Khayms, Vadim; Scholz, Edwin

    2016-05-01

    Gas flow heating using radio frequency plasmas offers the possibility of depositing power in the centre of the flow rather than on the outside, as is the case with electro-thermal systems where thermal wall losses lower efficiency. Improved systems for space propulsion are one possible application and we have tested a prototype micro-thruster on a thrust balance in vacuum. For these initial tests, a fixed component radio frequency matching network weighing 90 grams was closely attached to the thruster in vacuum with the frequency agile radio frequency generator power being delivered via a 50 Ohm cable. Without accounting for system losses (estimated at around 50%), for a few 10s of Watts from the radio frequency generator the specific impulse was tripled to ˜48 seconds and the thrust tripled from 0.8 to 2.4 milli-Newtons.

  19. Solution cathode glow discharge induced vapor generation of mercury and its application to mercury speciation by high performance liquid chromatography-atomic fluorescence spectrometry.

    PubMed

    He, Qian; Zhu, Zhenli; Hu, Shenghong; Jin, Lanlan

    2011-07-15

    A novel solution cathode glow discharge (SCGD) induced vapor generation was developed as interface to on-line couple high-performance liquid chromatography (HPLC) with atomic fluorescence spectrometry (AFS) for the speciation of inorganic mercury (Hg(2+)), methyl-mercury (MeHg) and ethyl-mercury (EtHg). The decomposition of organic mercury species and the reduction of Hg(2+) could be completed in one step with this proposed SCGD induced vapor generation system. The vapor generation is extremely rapid and therefore is easy to couple with flow injection (FI) and HPLC. Compared with the conventional HPLC-CV-AFS hyphenated systems, the proposed HPLC-SCGD-AFS system is very simple in operation and eliminates auxiliary redox reagents. Parameters influencing mercury determination were optimized, such as concentration of formic acid, discharge current and argon flow rate. The method detection limits for HPLC-SCGD-AFS system were 0.67 μg L(-1) for Hg(2+), 0.55 μg L(-1) for MeHg and 1.19 μg L(-1) for EtHg, respectively. The developed method was validated by determination of certified reference material (GBW 10029, tuna fish) and was further applied for the determination of mercury in biological samples. PMID:21641599

  20. Determination of mercury in fish otoliths by cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS)†

    PubMed Central

    Kenduzler, Erdal; Ates, Mehmet; Arslan, Zikri; McHenry, Melanie; Tchounwou, Paul B.

    2012-01-01

    A method based on cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS) has been developed for determination of inorganic mercury, Hg(II), and total mercury in fish otoliths. Sodium borohydride (NaBH4) was used as the only reducing agent and its concentration was optimized across an acidity gradient to selectively reduce Hg(II) without affecting methylmercury, CH3Hg(I). Inorganic Hg was quantitatively reduced to elemental mercury (Hg0) with 1×10−4% (m/v) NaBH4. CH3Hg(I) required a minimum of 0.5% (m/v) NaBH4 for complete reduction. Increasing the HCl concentration of solution to 5% (v/v) improved the selectivity toward Hg(II) as it decreased the signals from CH3Hg(I) to baseline levels. Potassium ferricyanide solution was the most effective in eliminating the memory effects of Hg compared with a number of chelating and oxidizing agents, including EDTA, gold chloride, thiourea, cerium ammonium nitrate and 2-mercaptoethylamine chloride. The relative standard deviation (RSD) was less than 5% for 1.0 μg L−1 Hg(II) solution. The detection limits were 4.2 and 6.4 ng L−1 (ppt) for Hg(II) and total Hg, respectively. Sample dissolution conditions and recoveries were examined with ultra-pure CaCO3 (99.99%) spiked with Hg(II) and CH3HgCl. Methylmercury was stable when dissolution was performed with up to 20% (v/v) HCl at 100 oC. Recoveries from spiked solutions were higher than 95% for both Hg(II) and CH3Hg(I). The method was applied to the determination of Hg(II) and total Hg concentrations in the otoliths of red emperor (CRM 22) and Pacific halibut. Total Hg concentration in the otoliths was 0.038 ± 0.004 μg g−1 for the red emperor and 0.021 ± 0.003 μg g−1 for the Pacific halibut. Inorganic Hg accounted for about 25% of total Hg indicating that Hg in the otoliths was predominantly organic mercury (e.g., methylmercury). However, as opposed to the bioaccumulation in tissues, methylmercury levels in otoliths was very low suggesting a

  1. Determination of mercury in fish otoliths by cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS).

    PubMed

    Kenduzler, Erdal; Ates, Mehmet; Arslan, Zikri; McHenry, Melanie; Tchounwou, Paul B

    2012-05-15

    A method based on cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS) has been developed for determination of inorganic mercury, Hg(II), and total mercury in fish otoliths. Sodium borohydride (NaBH(4)) was used as the only reducing agent and its concentration was optimized across an acidity gradient to selectively reduce Hg(II) without affecting methylmercury, CH(3)Hg(I). Inorganic Hg was quantitatively reduced to elemental mercury (Hg(0)) with 1 × 10(-4)% (m/v) NaBH(4). CH(3)Hg(I) required a minimum of 0.5% (m/v) NaBH(4) for complete reduction. Increasing the HCl concentration of solution to 5% (v/v) improved the selectivity toward Hg(II) as it decreased the signals from CH(3)Hg(I) to baseline levels. Potassium ferricyanide solution was the most effective in eliminating the memory effects of Hg compared with a number of chelating and oxidizing agents, including EDTA, gold chloride, thiourea, cerium ammonium nitrate and 2-mercaptoethylamine chloride. The relative standard deviation (RSD) was less than 5% for 1.0 μg L(-1) Hg(II) solution. The detection limits were 4.2 and 6.4 ng L(-1) (ppt) for Hg(II) and total Hg, respectively. Sample dissolution conditions and recoveries were examined with ultra-pure CaCO(3) (99.99%) spiked with Hg(II) and CH(3)HgCl. Methylmercury was stable when dissolution was performed with up to 20% (v/v) HCl at 100°C. Recoveries from spiked solutions were higher than 95% for both Hg(II) and CH(3)Hg(I). The method was applied to the determination of Hg(II) and total Hg concentrations in the otoliths of red emperor (CRM 22) and Pacific halibut. Total Hg concentration in the otoliths was 0.038 ± 0.004 μg g(-1) for the red emperor and 0.021 ± 0.003 μg g(-1) for the Pacific halibut. Inorganic Hg accounted for about 25% of total Hg indicating that Hg in the otoliths was predominantly organic mercury (e.g., methylmercury). However, as opposed to the bioaccumulation in tissues, methylmercury levels in otoliths was

  2. Simulations of electrothermal instability growth in solid aluminum rodsa)

    NASA Astrophysics Data System (ADS)

    Peterson, Kyle J.; Yu, Edmund P.; Sinars, Daniel B.; Cuneo, Michael E.; Slutz, Stephen A.; Koning, Joseph M.; Marinak, Michael M.; Nakhleh, Charles; Herrmann, Mark C.

    2013-05-01

    A recent publication [K. J. Peterson et al., Phys. Plasmas 19, 092701 (2012)] describes simulations and experiments of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns rise time current pulse on Sandia National Laboratories Z accelerator. Quantitative analysis of the high precision radiography data obtained in the experiments showed excellent agreement with simulations and demonstrated levels of instability growth in dense matter that could not be explained by magneto-Rayleigh-Taylor instabilities alone. This paper extends the previous one by examining the nature of the instability growth in 2D simulations in much greater detail. The initial instability growth in the simulations is shown via several considerations to be predominantly electrothermal in nature and provides a seed for subsequent magneto-Rayleigh-Taylor growth.

  3. Improving Battery Design with Electro-Thermal Modeling: Preprint

    SciTech Connect

    Pesaran, A.; Bharathan, D.; Kim, G.; Vlahinos, A.; Duong, T.

    2005-04-01

    Temperature greatly affects the performance and life of batteries in electric and hybrid vehicles under real driving conditions, so increased attention is being paid to battery thermal management. Sophisticated electrochemical models and finite element analysis tools are available for predicting the thermal performance of batteries, but each has limitations. In this study we describe an electro-thermal finite element approach that predicts the thermal performance of a cell or module with realistic geometry, material properties, loads, and boundary conditions.

  4. Electro-thermal simulation of superconducting nanowire avalanche photodetectors

    SciTech Connect

    Marsili, F.; Najafi, F.; Herder, C.; Berggren, K. K.

    2011-01-01

    We developed an electrothermal model of NbN superconducting nanowire avalanche photodetectors (SNAPs) on sapphire substrates. SNAPs are single-photon detectors consisting of the parallel connection of N superconducting nanowires. We extrapolated the physical constants of the model from experimental data and we simulated the time evolution of the device resistance, temperature and current by solving two coupled electrical and thermal differential equations describing the nanowires. The predictions of the model were in good quantitative agreement with the experimental results.

  5. Electro-Thermal Modeling to Improve Battery Design: Preprint

    SciTech Connect

    Bharathan, D.; Pesaran, A.; Kim, G.; Vlahinos, A.

    2005-09-01

    Operating temperature greatly affects the performance and life of batteries in electric and hybrid electric vehicles (HEVs). Increased attention is necessary to battery thermal management. Electrochemical models and finite element analysis tools are available for predicting the thermal performance of batteries, but each has limitations. This study describes an electro-thermal finite element approach that predicts the thermal performance of a battery cell or module with realistic geometry.

  6. Improving Battery Design with Electro-Thermal Modeling

    SciTech Connect

    Pesaran, A.; Vlahinos, A.; Bharathan, D.; Kim, G.-H.; Duong, T.

    2005-08-01

    Temperature greatly affects the performance and life of batteries in electric and hybrid vehicles under real driving conditions, so increased attention is being paid to battery thermal management. Sophisticated electrochemical models and finite element analysis tools are available for predicting the thermal performance of batteries, but each has limitations. In this study we describe an electro-thermal finite element approach that predicts the thermal performance of a cell or module with realistic geometry, material properties, loads, and boundary conditions.

  7. MEMS-based silicon cantilevers with integrated electrothermal heaters for airborne ultrafine particle sensing

    NASA Astrophysics Data System (ADS)

    Wasisto, Hutomo Suryo; Merzsch, Stephan; Waag, Andreas; Peiner, Erwin

    2013-05-01

    The development of low-cost and low-power MEMS-based cantilever sensors for possible application in hand-held airborne ultrafine particle monitors is described in this work. The proposed resonant sensors are realized by silicon bulk micromachining technology with electrothermal excitation, piezoresistive frequency readout, and electrostatic particle collection elements integrated and constructed in the same sensor fabrication process step of boron diffusion. Built-in heating resistor and full Wheatstone bridge are set close to the cantilever clamp end for effective excitation and sensing, respectively, of beam deflection. Meanwhile, the particle collection electrode is located at the cantilever free end. A 300 μm-thick, phosphorus-doped silicon bulk wafer is used instead of silicon-on-insulator (SOI) as the starting material for the sensors to reduce the fabrication costs. To etch and release the cantilevers from the substrate, inductively coupled plasma (ICP) cryogenic dry etching is utilized. By controlling the etching parameters (e.g., temperature, oxygen content, and duration), cantilever structures with thicknesses down to 10 - 20 μm are yielded. In the sensor characterization, the heating resistor is heated and generating thermal waves which induce thermal expansion and further cause mechanical bending strain in the out-of-plane direction. A resonant frequency of 114.08 +/- 0.04 kHz and a quality factor of 1302 +/- 267 are measured in air for a fabricated rectangular cantilever (500x100x13.5 μm3). Owing to its low power consumption of a few milliwatts, this electrothermal cantilever is suitable for replacing the current external piezoelectric stack actuator in the next generation of the miniaturized cantilever-based nanoparticle detector (CANTOR).

  8. Thermal characterization of large size lithium-ion pouch cell based on 1d electro-thermal model

    NASA Astrophysics Data System (ADS)

    Vertiz, G.; Oyarbide, M.; Macicior, H.; Miguel, O.; Cantero, I.; Fernandez de Arroiabe, P.; Ulacia, I.

    2014-12-01

    Thermal management is one of the key factors to keep lithium-ion cells in optimum electrical performance, under safe working conditions and into a reasonably low ageing process. This issue is becoming particularly relevant due to the heterogeneous heat generation along the cell. Cell working temperature is determined by ambient temperature, heat generation and evacuation capacity. Therefore, thermal management is established by: i) the intrinsic thermal properties (heat capacity & thermal conductivity) and ii) the heat generation electro-thermal parameters (internal resistance, open circuit voltage & entropic factor). In this research, different methods - calculated and experimental - are used to characterize the main heat properties of a 14Ah -LiFePO4/graphite-commercial large sizes pouch cell. In order to evaluate the accuracy of methods, two comparisons were performed. First, Newman heat generation estimations were compared with experimental heat measurements. Secondly, empirical thermal cell behaviour was match with 1D electro-thermal model response. Finally, considering the results, the most adequate methodology to evaluate the key thermal parameters of a large size Lithium-ion pouch cell are proposed to be: i) pulse method for internal resistance, ii)heat loss method for entropic factor; and iii)experimental measurement (ARC calorimeter and C-177-97 standard method) for heat capacity and thermal conductivity.

  9. Electrothermal Fluid Manipulation of High-Conductivity Samples for Laboratory Automation Applications

    PubMed Central

    Sin, Mandy L. Y.; Gau, Vincent; Liao, Joseph C.; Wong, Pak Kin

    2010-01-01

    Electrothermal flow is a promising technique in microfluidic manipulation toward laboratory automation applications, such as clinical diagnostics and high throughput drug screening. Despite the potential of electrothermal flow in biomedical applications, relative little is known about electrothermal manipulation of highly conductive samples, such as physiological fluids and buffer solutions. In this study, the characteristics and challenges of electrothermal manipulation of fluid samples with different conductivities were investigated systematically. Electrothermal flow was shown to create fluid motion for samples with a wide range of conductivity when the driving frequency was above 100 kHz. For samples with low conductivities (below 1 S/m), the characteristics of the electrothermal fluid motions were in quantitative agreement with the theory. For samples with high conductivities (above 1 S/m), the fluid motion appeared to deviate from the model as a result of potential electrochemical reactions and other electrothermal effects. These effects should be taken into consideration for electrothermal manipulation of biological samples with high conductivities. This study will provide insights in designing microfluidic devices for electrokinetic manipulation of biological samples toward laboratory automation applications in the future. PMID:21180401

  10. Vapor shielding effects on energy transfer from plasma-gun generated ELM-like transient loads to material surfaces

    NASA Astrophysics Data System (ADS)

    Kikuchi, Y.; Sakuma, I.; Asai, Y.; Onishi, K.; Isono, W.; Nakazono, T.; Nakane, M.; Fukumoto, N.; Nagata, M.

    2016-02-01

    Energy transfer processes from ELM-like pulsed helium (He) plasmas with a pulse duration of ˜0.1 ms to aluminum (Al) and tungsten (W) surfaces were experimentally investigated by the use of a magnetized coaxial plasma gun device. The surface absorbed energy density of the He pulsed plasma on the W surface measured with a calorimeter was ˜0.44 MJ m-2, whereas it was ˜0.15 MJ m-2 on the Al surface. A vapor layer in front of the Al surface exposed to the He pulsed plasma was clearly identified by Al neutral emission line (Al i) measured with a high time resolution spectrometer, and fast imaging with a high-speed visible camera filtered around the Al i emission line. On the other hand, no clear evaporation in front of the W surface exposed to the He pulsed plasma was observed in the present condition. Discussions on the reduction in the surface absorbed energy density on the Al surface are provided by considering the latent heat of vaporization and radiation cooling due to the Al vapor cloud.

  11. Monitoring variations of dimethyl sulfide and dimethylsulfoniopropionate in seawater and the atmosphere based on sequential vapor generation and ion molecule reaction mass spectrometry.

    PubMed

    Iyadomi, Satoshi; Ezoe, Kentaro; Ohira, Shin-Ichi; Toda, Kei

    2016-04-20

    To monitor the fluctuations of dimethyl sulfur compounds at the seawater/atmosphere interface, an automated system was developed based on sequential injection analysis coupled with vapor generation-ion molecule reaction mass spectrometry (SIA-VG-IMRMS). Using this analytical system, dissolved dimethyl sulfide (DMSaq) and dimethylsulfoniopropionate (DMSP), a precursor to DMS in seawater, were monitored together sequentially with atmospheric dimethyl sulfide (DMSg). A shift from the equilibrium point between DMSaq and DMSg results in the emission of DMS to the atmosphere. Atmospheric DMS emitted from seawater plays an important role as a source of cloud condensation nuclei, which influences the oceanic climate. Water samples were taken periodically and dissolved DMSaq was vaporized for analysis by IMRMS. After that, DMSP was hydrolyzed to DMS and acrylic acid, and analyzed in the same manner as DMSaq. The vaporization behavior and hydrolysis of DMSP to DMS were investigated to optimize these conditions. Frequent (every 30 min) determination of the three components, DMSaq/DMSP (nanomolar) and DMSg (ppbv), was carried out by SIA-VG-IMRMS. Field analysis of the dimethyl sulfur compounds was undertaken at a coastal station, which succeeded in showing detailed variations of the compounds in a natural setting. Observed concentrations of the dimethyl sulfur compounds both in the atmosphere and seawater largely changed with time and similar variations were repeatedly observed over several days, suggesting diurnal variations in the DMS flux at the seawater/atmosphere interface. PMID:27046734

  12. Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of As, Cd, and Hg in cereals.

    PubMed

    Chen, Feng-Yi; Jiang, Shiuh-Jen

    2009-08-12

    A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of As, Cd, and Hg in cereals using flow injection chemical vapor generation (VG) as the sample introduction system. A slurry containing 6% m/v flour, 0.7% m/v thiourea, 0.4 microg mL(-1) Co(II), and 2.5% v/v HCl was injected into a VG-ICP-MS system for the determination of As, Cd, and Hg without dissolution and mineralization. Because the sensitivities of the elements studied in the slurry and that of aqueous solution were quite different, a standard addition method and an isotope dilution method were used for the determination of As, Cd, and Hg in selected cereal samples. The influences of vapor generation conditions and slurry preparation on the ion signals were reported. The effectiveness of the vapor generation sample introduction technique in alleviating various spectral interferences in ICP-MS analysis has been demonstrated. This method has been applied for the determination of As, Cd, and Hg in NIST SRM 1567a Wheat Flour reference material, NIST SRM 1568a Rice Flour reference material, and cereal samples obtained from local market. The As, Cd, and Hg analysis results of the reference materials agreed with the certified values. The method detection limits estimated from standard addition curves were about 0.10, 0.16, and 0.07 ng g(-1) for As, Cd, and Hg, respectively, in the original cereal samples. PMID:19606866

  13. 4.7-W, 255-nm source based on second-harmonic generation of a copper-vapor laser in cesium lithium borate.

    PubMed

    Trickett, R I; Withford, M J; Brown, D J

    1998-02-01

    We have generated 4.7 W of UV (255-nm) radiation with wall plug efficiency of 0.12% by frequency doubling the green (511-nm) output of a kinetically enhanced medium-scale copper-vapor laser (CVL) in cesium lithium borate (CLBO). Frequency doubling in beta -barium borate produced 3.9 W of UV radiation with wall plug efficiency of 0.1%. We found that conversion was better with CLBO because of the reduced constraints on CVL beam quality, less UV absorption, and smaller UV walk-off. PMID:18084455

  14. Determination of Se in biological samples by axial view inductively coupled plasma optical emission spectrometry after digestion with aqua regia and on-line chemical vapor generation

    NASA Astrophysics Data System (ADS)

    dos Santos, Éder José; Herrmann, Amanda Beatriz; de Caires, Suzete Kulik; Frescura, Vera Lúcia Azzolin; Curtius, Adilson José

    2009-06-01

    A simple and fast method for the determination of Se in biological samples, including food, by axial view inductively coupled plasma optical emission spectrometry using on-line chemical vapor generation (CVG-ICP OES) is proposed. The concentrations of HCl and NaBH 4, used in the chemical vapor generation were optimized by factorial analysis. Six certified materials (non-fat milk powder, lobster hepatopancreas, human hair, whole egg powder, oyster tissue, and lyophilised pig kidney) were treated with 10 mL of aqua regia in a microwave system under reflux for 15 min followed by additional 15 min in an ultrasonic bath. The solutions were transferred to a 100 mL volumetric flask and the final volume was made up with water. The Se was determined directly in these solutions by CVG-ICP OES, using the analytical line at 196.026 nm. Calibration against aqueous standards in 10% v/v aqua regia in the concentration range of 0.5-10.0 µg L - 1 Se(IV) was used for the analysis. The quantification limit, considering a 0.5 g sample weight in a final volume of 100 mL - 1 was 0.10 µg g - 1. The obtained concentration values were in agreement with the total certified concentrations, according to the t-test for a 95% confidence level.

  15. Determination of mercury compounds in fish by microwave-assisted extraction and liquid chromatography-vapor generation-inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Chiou, Chwei-Sheng; Jiang, Shiuh-Jen; Kumar Danadurai, K. Suresh

    2001-07-01

    A method employing a vapor generation system and LC combined with inductively coupled plasma mass spectrometry (LC-ICP-MS) is presented for the determination of mercury in biological tissues. An open vessel microwave digestion system was used to extract the mercury compounds from the sample matrix. The efficiency of the mobile phase, a mixture of L-cysteine and 2-mercaptoethanol, was evaluated for LC separation of inorganic mercury [Hg(II)], methylmercury (methyl-Hg) and ethylmercury (ethyl-Hg). The sensitivity, detection limits and repeatability of the liquid chromatography (LC) ICP-MS system with a vapor generator were comparable to, or better than, that of an LC-ICP-MS system with conventional pneumatic nebulization, or other sample introduction techniques. The experimental detection limits for various mercury species were in the range of 0.05-0.09 ng ml -1 Hg, based on peak height. The proposed method was successfully applied to the determination of mercury compounds in a swordfish sample purchased from the local market. The accuracy of the method was evaluated by analyzing a marine biological certified reference material (DORM-2, NRCC).

  16. Enhancing vapor generation at a liquid-solid interface using micro/nanoscale surface structures fabricated by femtosecond laser surface processing

    NASA Astrophysics Data System (ADS)

    Anderson, Troy P.; Wilson, Chris; Zuhlke, Craig A.; Kruse, Corey; Gogos, George; Ndao, Sidy; Alexander, Dennis

    2015-03-01

    Femtosecond Laser Surface Processing (FLSP) is a versatile technique for the fabrication of a wide variety of micro/nanostructured surfaces with tailored physical and chemical properties. Through control over processing conditions such as laser fluence, incident pulse count, polarization, and incident angle, the size and density of both micrometer and nanometer-scale surface features can be tailored. Furthermore, the composition and pressure of the environment both during and after laser processing have a substantial impact on the final surface chemistry of the target material. FLSP is therefore a powerful tool for optimizing interfacial phenomena such as wetting, wicking, and phasetransitions associated with a vapor/liquid/solid interface. In the present study, we utilize a series of multiscale FLSPgenerated surfaces to improve the efficiency of vapor generation on a structured surface. Specifically, we demonstrate that FLSP of stainless steel 316 electrode surfaces in an alkaline electrolysis cell results in increased efficiency of the water-splitting reaction used to generate hydrogen. The electrodes are fabricated to be superhydrophilic (the contact angle of a water droplet on the surface is less than 5 degrees). The overpotential of the hydrogen evolution reaction (HER) is measured using a 3-electrode configuration with a structured electrode as the working electrode. The enhancement is attributed to several factors including increased surface area, increased wettability, and the impact of micro/nanostructures on the bubble formation and release. Special emphasis is placed on identifying and isolating the relative impacts of the various contributions.

  17. Electro-thermally actuated microgrippers with integrated force-feedback

    NASA Astrophysics Data System (ADS)

    Mølhave, Kristian; Hansen, Ole

    2005-06-01

    Microfabricated grippers and tweezers are promising tools for manipulation of micro- and nanoscale objects. As with ordinary macroscale grippers, the ability to sense the forces involved in grabbing would be advantageous for controlling the operation as well as for measuring the mechanical properties of the grabbed object. A simple design is presented for an electro-thermally actuated microfabricated gripper capable of providing a piezoresistive read-out of the gripper deflection, which can be used to measure the forces applied to the grabbed object. Measurements of actuation of test devices are presented and found to be in reasonable agreement with expected values. Finally, piezoresistive measurements of the gripper deflection are demonstrated.

  18. Vapor resistant arteries

    NASA Technical Reports Server (NTRS)

    Shaubach, Robert M. (Inventor); Dussinger, Peter M. (Inventor); Buchko, Matthew T. (Inventor)

    1989-01-01

    A vapor block resistant liquid artery structure for heat pipes. A solid tube artery with openings is encased in the sintered material of a heat pipe wick. The openings are limited to that side of the artery which is most remote from the heat source. The liquid in the artery can thus exit the artery through the openings and wet the sintered sheath, but vapor generated at the heat source is unlikely to move around the solid wall of the artery and reverse its direction in order to penetrate the artery through the openings. An alternate embodiment uses finer pore size wick material to resist vapor entry.

  19. Self-generating magnetometer with laser pumping employment in “end resonance” wall coated vapor cell atomic clocks

    NASA Astrophysics Data System (ADS)

    Baranov, A. A.; Ermak, S. V.; Smolin, R. V.; Semenov, V. V.

    2016-06-01

    This paper presents the results of two double resonance signals correlation investigation. These signals were observed synchronously in optically oriented Rb87 vapors with laser pumping in a dual scheme: low frequency Mx-magnetometer and microwave frequency discriminator. Analytical studies of the scalar and vector light shift components contribution to the frequency instability of the end resonance microwave transitions are presented. An experimental demonstration of the light shift components mutual compensation in optically pumped Rb87 atoms was provided. The results were processed in terms of Allan variance, which demonstrated an effect of decreasing frequency variation at averaging times more than 100 s for a joint scheme of the end resonance microwave transition and selfgenerating (Mx) magnetometer.

  20. An electro-thermally activated rotary micro-positioner for slider-level dual-stage positioning in hard disk drives

    NASA Astrophysics Data System (ADS)

    Keong Lau, Gih; Yang, Jiaping; Tan, Cheng Peng; Boon Chong, Nyok

    2016-03-01

    Slider-level micro-positioners are useful to assist a voice coil motor to perform fine head positioning over a Tb/in2 magnetic disk. Recently, a new kind of slider-level micro-positioner was developed using the thermal unimorph of the Si/SU8 composite. It has the advantages of a very small footprint and high mechanical resonant frequency, but its stroke generation is inadequate, with a 50 nm dynamic stroke at 1 kHz. There is a need for a larger thermally induced stroke. This paper presents a rotary design of an electrothermal micro-positioner to address the stroke requirements without consuming more power or decreasing the mechanical resonant frequency. Experimental studies show the present rotary design can produce a six-fold larger displacement, as compared to the previous lateral design, while possessing a 35 kHz resonant frequency. In addition, simple analytical models were developed to estimate: (i) the rotational stiffness and system’s natural frequency, (ii) thermal unimorph bending and stage rotation, and (iii) the system’s thermal time constant for this rotary electro-thermal micro-positioner. This study found that this rotary electro-thermal micro-positioner can meet the basic stroke requirement and high mechanical resonant frequency for a moving slider, but its thermal cut-off frequency needs to be increased further.

  1. Sol-Generating Chemical Vapor into Liquid (SG-CViL) Deposition- A Facile Method for Encapsulation of Diverse Cell Types in Silica Matrices

    PubMed Central

    Johnston, Robert; Rogelj, Snezna; Harper, Jason C.; Tartis, Michaelann

    2014-01-01

    In nature, cells perform a variety of complex functions such as sensing, catalysis, and energy conversion which hold great potential for biotechnological device construction. However, cellular sensitivity to ex-vivo environments necessitates development of bio-nano interfaces which allow integration of cells into devices and maintain their desired functionality. In order to develop such an interface, the use of a novel Sol Generating Chemical Vapor into Liquid (SG-CViL) deposition process for whole cell encapsulation in silica was explored. In SG-CViL, the high vapor pressure of tetramethyl orthosilicate (TMOS) is utilized to deliver silica into an aqueous medium, creating a silica sol. Cells are then mixed with the resulting silica sol, facilitating encapsulation of cells in silica while minimizing cell contact with the cytotoxic products of silica generating reactions (i.e. methanol), and reduce exposure of cells to compressive stresses induced from silica condensation reactions. Using SG-CVIL, Saccharomyces cerevisiae (S. cerevisiae) engineered with an inducible beta galactosidase system were encapsulated in silica solids and remained both viable and responsive 29 days post encapsulation. By tuning SG-CViL parameters thin layer silica deposition on mammalian HeLa and U87 human cancer cells was also achieved. The ability to encapsulate various cell types in either a multi cell (S. cerevisiae) or a thin layer (HeLa and U87 cells) fashion shows the promise of SG-CViL as an encapsulation strategy for generating cell-silica constructs with diverse functions for incorporation into devices for sensing, bioelectronics, biocatalysis, and biofuel applications. PMID:25688296

  2. Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition – A facile method for encapsulation of diverse cell types in silica matrices

    SciTech Connect

    Johnston, Robert; Rogelj, Snezna; Harper, Jason C.; Tartis, Michaelann

    2014-12-12

    In nature, cells perform a variety of complex functions such as sensing, catalysis, and energy conversion which hold great potential for biotechnological device construction. However, cellular sensitivity to ex vivo environments necessitates development of bio–nano interfaces which allow integration of cells into devices and maintain their desired functionality. In order to develop such an interface, the use of a novel Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition process for whole cell encapsulation in silica was explored. In SG-CViL, the high vapor pressure of tetramethyl orthosilicate (TMOS) is utilized to deliver silica into an aqueous medium, creating a silica sol. Cells are then mixed with the resulting silica sol, facilitating encapsulation of cells in silica while minimizing cell contact with the cytotoxic products of silica generating reactions (i.e. methanol), and reduce exposure of cells to compressive stresses induced from silica condensation reactions. Using SG-CVIL, Saccharomyces cerevisiae (S. cerevisiae) engineered with an inducible beta galactosidase system were encapsulated in silica solids and remained both viable and responsive 29 days post encapsulation. By tuning SG-CViL parameters, thin layer silica deposition on mammalian HeLa and U87 human cancer cells was also achieved. Furthermore, the ability to encapsulate various cell types in either a multi cell (S. cerevisiae) or a thin layer (HeLa and U87 cells) fashion shows the promise of SG-CViL as an encapsulation strategy for generating cell–silica constructs with diverse functions for incorporation into devices for sensing, bioelectronics, biocatalysis, and biofuel applications.

  3. Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition – A facile method for encapsulation of diverse cell types in silica matrices

    DOE PAGESBeta

    Johnston, Robert; Rogelj, Snezna; Harper, Jason C.; Tartis, Michaelann

    2014-12-12

    In nature, cells perform a variety of complex functions such as sensing, catalysis, and energy conversion which hold great potential for biotechnological device construction. However, cellular sensitivity to ex vivo environments necessitates development of bio–nano interfaces which allow integration of cells into devices and maintain their desired functionality. In order to develop such an interface, the use of a novel Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition process for whole cell encapsulation in silica was explored. In SG-CViL, the high vapor pressure of tetramethyl orthosilicate (TMOS) is utilized to deliver silica into an aqueous medium, creating a silica sol. Cellsmore » are then mixed with the resulting silica sol, facilitating encapsulation of cells in silica while minimizing cell contact with the cytotoxic products of silica generating reactions (i.e. methanol), and reduce exposure of cells to compressive stresses induced from silica condensation reactions. Using SG-CVIL, Saccharomyces cerevisiae (S. cerevisiae) engineered with an inducible beta galactosidase system were encapsulated in silica solids and remained both viable and responsive 29 days post encapsulation. By tuning SG-CViL parameters, thin layer silica deposition on mammalian HeLa and U87 human cancer cells was also achieved. Furthermore, the ability to encapsulate various cell types in either a multi cell (S. cerevisiae) or a thin layer (HeLa and U87 cells) fashion shows the promise of SG-CViL as an encapsulation strategy for generating cell–silica constructs with diverse functions for incorporation into devices for sensing, bioelectronics, biocatalysis, and biofuel applications.« less

  4. Effects of an Early-Time Impact Generated Vapor Blast in the Martian Atmosphere: Formation of High-Latitude Pedestal Craters

    NASA Technical Reports Server (NTRS)

    Wrobel, K. E.; Schultz, P. H.; Crawford, D. A.

    2005-01-01

    Following impact, vapor expansion creates an intense airblast that interacts with the ambient atmosphere. The resulting hemi-spherical shock wave leaves a signature on the surface that is dependent on initial atmospheric and surface conditions. Here we propose that the formation of pedestal craters (craters surrounded by an erosion-resistant pedestal) may be a direct consequence of extreme winds and elevated temperatures generated by such an impact-induced atmospheric blast. Pedestal craters, first recognized in Mariner 9 data, are a unique feature on Mars and likely a signature of near-surface volatiles. They are found at high latitudes (small pedestals, Amazonian to Late Hesperian in age) and in thick equatorial mantling deposits (larger pedestals, early Hesperian to Noachian in age). Previously suggested mechanisms for pedestal crater formation (e.g., wind: ejecta curtain vortices or vapor blast; and ejecta dust: armoring) do not provide a complete picture. The clear evidence for near-surface volatiles at high latitudes requires a re-evaluation of these alternative models. The results presented here suggest that a combined atmospheric blast/thermal model provides a plausible formation hypothesis.

  5. The automated multiwavelength Raman polarization and water-vapor lidar PollyXT: the neXT generation

    NASA Astrophysics Data System (ADS)

    Engelmann, Ronny; Kanitz, Thomas; Baars, Holger; Heese, Birgit; Althausen, Dietrich; Skupin, Annett; Wandinger, Ulla; Komppula, Mika; Stachlewska, Iwona S.; Amiridis, Vassilis; Marinou, Eleni; Mattis, Ina; Linné, Holger; Ansmann, Albert

    2016-04-01

    The atmospheric science community demands autonomous and quality-assured vertically resolved measurements of aerosol and cloud properties. For this purpose, a portable lidar called Polly was developed at TROPOS in 2003. The lidar system was continuously improved with gained experience from the EARLINET community, involvement in worldwide field campaigns, and international institute collaborations within the last 10 years. Here we present recent changes of the setup of the portable multiwavelength Raman and polarization lidar PollyXT and discuss the improved capabilities of the system by means of a case study. The latest system developments include an additional near-range receiver unit for Raman measurements of the backscatter and extinction coefficient down to 120 m above ground, a water-vapor channel, and channels for simultaneous measurements of the particle linear depolarization ratio at 355 and 532 nm. Quality improvements were achieved by systematically following the EARLINET guidelines and the international PollyNET quality assurance developments. A modified ship radar ensures measurements in agreement with air-traffic safety regulations and allows for 24/7 monitoring of the atmospheric state with PollyXT.

  6. Electro-thermal impedance spectroscopy applied to an open-cathode polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Engebretsen, Erik; Robinson, James B.; Obeisun, Oluwamayowa; Mason, Tom; Finegan, Donal; Hinds, Gareth; Shearing, Paul R.; Brett, Daniel J. L.

    2016-01-01

    The development of in-situ diagnostic techniques is critical to ensure safe and effective operation of polymer electrolyte fuel cell systems. Infrared thermal imaging is an established technique which has been extensively applied to fuel cells; however, the technique is limited to measuring surface temperatures and is prone to errors arising from emissivity variations and reflections. Here we demonstrate that electro-thermal impedance spectroscopy can be applied to enhance infrared thermal imaging and mitigate its limitations. An open-cathode polymer electrolyte fuel cell is used as a case study. The technique operates by imposing a periodic electrical stimulus to the fuel cell and measuring the consequent surface temperature response (phase and amplitude). In this way, the location of heat generation from within the component can be determined and the thermal conduction properties of the materials and structure between the point of heat generation and the point of measurement can be determined. By selectively 'locking-in' to a suitable modulation frequency, spatially resolved images of the relative amplitude between the current stimulus and temperature can be generated that provide complementary information to conventional temporal domain thermograms.

  7. Coaxial microwave electrothermal thruster performance in hydrogen

    NASA Technical Reports Server (NTRS)

    Richardson, W.; Asmussen, J.; Hawley, M.

    1994-01-01

    The microwave electro thermal thruster (MET) is an electric propulsion concept that offers the promise of high performance combined with a long lifetime. A unique feature of this electric propulsion concept is its ability to create a microwave plasma discharge separated or floating away from any electrodes or enclosing walls. This allows propellant temperatures that are higher than those in resistojets and reduces electrode and wall erosion. It has been demonstrated that microwave energy is coupled into discharges very efficiently at high input power levels. As a result of these advantages, the MET concept has been identified as a future high power electric propulsion possibility. Recently, two additional improvements have been made to the coaxial MET. The first was concerned with improving the microwave matching. Previous experiments were conducted with 10-30 percent reflected power when incident power was in excess of 600 W(exp 6). Power was reflected back to the generator because the impedance of the MET did not match the 50 ohm impedance of the microwave circuit. To solve this problem, a double stub tuning system has been inserted between the MET and the microwave power supply. The addition of the double stub tuners reduces the reflected power below 1 percent. The other improvement has prepared the coaxial MET for hydrogen experiments. To operate with hydrogen, the vacuum window which separates the coaxial line from the discharge chamber has been changed from teflon to boron nitride. All the microwave energy delivered to the plasma discharge passes through this vacuum window. This material change had caused problems in the past because of the increased microwave reflection coefficients associated with the electrical properties of boron nitride. However, by making the boron nitride window electrically one-half of a wavelength long, power reflection in the window has been eliminated. This technical note summarizes the experimental performance of the improved

  8. A MECHANISTIC MODEL FOR MERCURY CAPTURE WITH IN-SITU GENERATED TITANIA PARTICLES: ROLE OF WATER VAPOR

    EPA Science Inventory

    A mechanistic model to predict the capture of gas phase mercury species using in-situ generated titania nanosize particles activated by UV irradiation is developed. The model is an extension of a recently reported model1 for photochemical reactions that accounts for the rates of...

  9. 3D electro-thermal Monte Carlo study of transport in confined silicon devices

    NASA Astrophysics Data System (ADS)

    Mohamed, Mohamed Y.

    The simultaneous explosion of portable microelectronics devices and the rapid shrinking of microprocessor size have provided a tremendous motivation to scientists and engineers to continue the down-scaling of these devices. For several decades, innovations have allowed components such as transistors to be physically reduced in size, allowing the famous Moore's law to hold true. As these transistors approach the atomic scale, however, further reduction becomes less probable and practical. As new technologies overcome these limitations, they face new, unexpected problems, including the ability to accurately simulate and predict the behavior of these devices, and to manage the heat they generate. This work uses a 3D Monte Carlo (MC) simulator to investigate the electro-thermal behavior of quasi-one-dimensional electron gas (1DEG) multigate MOSFETs. In order to study these highly confined architectures, the inclusion of quantum correction becomes essential. To better capture the influence of carrier confinement, the electrostatically quantum-corrected full-band MC model has the added feature of being able to incorporate subband scattering. The scattering rate selection introduces quantum correction into carrier movement. In addition to the quantum effects, scaling introduces thermal management issues due to the surge in power dissipation. Solving these problems will continue to bring improvements in battery life, performance, and size constraints of future devices. We have coupled our electron transport Monte Carlo simulation to Aksamija's phonon transport so that we may accurately and efficiently study carrier transport, heat generation, and other effects at the transistor level. This coupling utilizes anharmonic phonon decay and temperature dependent scattering rates. One immediate advantage of our coupled electro-thermal Monte Carlo simulator is its ability to provide an accurate description of the spatial variation of self-heating and its effect on non

  10. Deposition of Fluorinated Diamond-Like-Carbon Films by Exposure of Electrothermal Pulsed Plasmas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Iida, Masayasu

    2011-08-01

    Thin amorphous carbon films are deposited on silicon substrates by exposure to pulsed plasmas where the feed gas is mainly generated from the ablation of an insulator. An electrothermal pulsed plasma thruster with a discharge room in an insulator rod is used as the pulsed plasma for the ablation of the insulator, and the material of the insulator rod is poly(tetrafluoroethylene) (PTFE). The pulsed plasma, in which the estimated electron density is on the order of 1022-1023 m-3, is generated by the stored energy in the capacitor. The deposition rate, which depends on the stored energy, is lower than 1 nm per pulse in our experiment. The maximum hardness measured using a nanoindenter is about 7 GPa at a stored energy of about 2.7 J, beyond which the hardness of the films decreases with the increase in stored energy. Raman spectroscopy is also carried out to examine the formation of fluorinated diamond-like carbon films. In addition, the influence of dilution gas on the properties of the deposited films is also investigated.

  11. Detection of zeptojoule microwave pulses using an electrothermal bifurcation

    NASA Astrophysics Data System (ADS)

    Govenius, Joonas; Lake, Russell; Tan, Kuan; Möttönen, Mikko

    We utilize electrothermal feedback for the threshold detection of weak 8.4 GHz microwave pulses containing approximately 200 × h × (8 . 4 GHz) ~ 1 . 1 ×10-21 J of energy. The feedback couples the electrical and thermal degrees of freedom in the central component of our detector, a metallic nanowire that absorbs the incoming microwave radiation and transduces the temperature change into a radio-frequency electrical signal. We can tune the feedback in situ, which provides access to both positive and negative feedback regimes with rich nonlinear dynamics. In particular, strong positive feedback leads to the emergence of two metastable electron temperature states in the millikelvin range. We use these states in the threshold detection protocol.

  12. A superconducting-nanowire three-terminal electrothermal device.

    PubMed

    McCaughan, Adam N; Berggren, Karl K

    2014-10-01

    Superconducting electronics based on Josephson junctions are used to sense and process electronic signals with minimal loss; however, they are ultrasensitive to magnetic fields, limited in their amplification capabilities, and difficult to manufacture. We have developed a 3-terminal, nanowire-based superconducting electrothermal device which has no Josephson junctions. This device, which we call the nanocryotron, can be patterned from a single thin film of superconducting material with conventional electron-beam lithography. The nanocryotron has a demonstrated gain of >20, can drive impedances of 100 kΩ, and operates in typical ambient magnetic fields. We have additionally applied it both as a digital logic element in a half-adder circuit, and as a digital amplifier for superconducting nanowire single-photon detectors pulses. The nanocryotron has immediate applications in classical and quantum communications, photon sensing, and astronomy, and its input characteristics are suitable for integration with existing superconducting technologies. PMID:25233488

  13. Operating principles of an electrothermal vibrometer for optical switching applications

    NASA Astrophysics Data System (ADS)

    Pai, Min-fan; Tien, Norman C.

    1999-09-01

    A compact polysilicon surface-micromachined microactuator designed for optical switching applications is described. This actuator is fabricated using the foundry MUMPs process provided by Cronos Integrated Microsystems Inc. Actuated electrothermally, the microactuator allows fast switching speeds and can be operated with a low voltage square-wave signal. The design, operation mechanisms for this long-range and high frequency thermal actuation are described. A vertical micromirror integrated with this actuator can be operated with a 10.5 V, 20 kHz 15% duty-cycle pulse signal, achieving a lateral moving speed higher than 15.6 mm/sec. The optical switch has been operated to frequencies as high as 30 kHz.

  14. Experimental investigation of the pulsed electrothermal (PET) thruster

    NASA Technical Reports Server (NTRS)

    Burton, R. L.; Goldstein, S. A.; Hiko, B. K.; Tidman, D. A.; Winsor, N. K.

    1984-01-01

    Burton et al. (1982) have discussed the theory of the Pulsed Electrothermal (PET) thruster, a device which in principle can operate with 70 percent efficiency at a specific impulse of 1000 seconds and higher. It is pointed out that this level of performance would be particularly attractive for orbit raising of large satellites and other near-earth missions, which cannot be easily accomplished by chemical propulsion. The present investigation is concerned with two PET thruster operating modes. A PET thruster was built and tested on a thrust stand. Exhaust velocities for polyethylene propellant vary from 20 to 27 km/sec. Single pulse specific impulse and efficiency measurements based on ablated mass show a thruster efficiency of 37-56 percent in the time range from 1000 to 1750 seconds. It is believed that an improved design with a thruster efficiency in the range from 70 to 80 percent might be possible.

  15. Experiments and analysis of a compact electrothermal thruster

    NASA Technical Reports Server (NTRS)

    Asmussen, Jes; Whitehair, Stan

    1988-01-01

    The description and experimental performance of a compact microwave electrothermal thruster (MET) are presented. This thruster uses a coaxial applicator to couple microwave power into a high pressure discharge. Unlike earlier experiments, it uses no fused quartz in the discharge chamber or the nozzle. This allows high temperatures in the discharge chamber without quartz erosion and melting, thereby improving thruster performance and lifetime. The thruster design is compact, enhancing its potential as a space engine. Experimental tests using nitrogen and helium propellants with input powers levels of 200 W to 1.5 kW are presented. Experimental results, which produce energy efficiencies of 20 to 60 percent and specific impulse of 250 to 450 sec, compare favorably to previous experimental MET performance.

  16. Single Port Electro-Thermal Propulsion—Performance Factors

    NASA Astrophysics Data System (ADS)

    Johansen, Donald G.

    2008-04-01

    Performance models for single port ETP (Electro-Thermal Propulsion) devices are presented considering all significant efficiency factors. Single-port ETP devices, which use the nozzle exit as entrance port for beamed power, are capable of high efficiency and high thrust with low mass penalty for both propellant and structure. Previously considered parabolic nozzle shapes have operated in pulse mode to exchange energy at a concentrated focal region, resulting in low efficiency. The proposed cone/bell shape diffuses the focal region prior to chamber entry to allow continuous combustion inside the chamber with high efficiency. Mechanical and thermal limits are evaluated. For vacuum operation, low chamber pressure operation is possible. Thin wall thruster construction results in low chamber and nozzle mass. Further, at low pressure, regenerative cooling is needed only for the chamber and throat region with radiation cooling for the nozzle exit region. These factors permit high expansion ratio and thrust-to-weight ratio needed for performance.

  17. Comparison of two lab-made spray chambers based on MSIS™ for simultaneous metal determination using vapor generation-inductively coupled plasma optical emission spectroscopy.

    PubMed

    Fuentes-Cid, A; Villanueva-Alonso, J; Peña-Vázquez, E; Bermejo-Barrera, P

    2012-10-24

    The objective of this study is to evaluate the performance of two lab-made systems based on the Multimode Introduction System (MSIS™) and the modified MSIS™, to generate and introduce vapors of Ag, Cu, Cd, Cu, Ni, Sn, Zn, and also Au in the ICP torch. An univariate procedure was used to select the optimized working conditions (Ar flow, sample, reductant and waste flows, and reagent concentrations). Optimum conditions for working with modified MSIS were: nitric acid concentration 0.35 M, 8-hydroxyquinoline concentration: 40 mg L(-1), sodium borohydride concentration: 1.75% (w/v)+0.4% (w/v) NaOH, argon purge flow to sweep the vapors to the torch: 1.2 L min(-1), sample flow and sodium borohydride flows: 2.3 L min(-1); waste flow: 7.7 mL min(-1). For the optimum working conditions for lab-made MSIS in dual mode the concentration of 8-hydroxyquinoline was 225 mg L(-1), the Ar purge flow was 0.75 L min(-1), and the conventional nebulization flow was 2.3 L min(-1). The sensitivity obtained was higher using the lab-made MSIS than using the lab-made modified MSIS or a forced outlet gas-liquid separator. The limits of detection were better for Au, Cd, Sn than those obtained using conventional nebulization; the measurements were precise (RSDs≤5% in dual mode) and a good accuracy was obtained in the determination of Cd, Cu, Ni and Zn in a wastewater reference material using aqueous calibration and the lab-made MSIS in dual mode. PMID:23036464

  18. Determination of methylmercury and inorganic mercury by coupling short-column ion chromatographic separation, on-line photocatalyst-assisted vapor generation, and inductively coupled plasma mass spectrometry.

    PubMed

    Chen, Kuan-ju; Hsu, I-hsiang; Sun, Yuh-chang

    2009-12-18

    We have combined short-column ion chromatographic separation and on-line photocatalyst-assisted vapor generation (VG) techniques with inductively coupled plasma mass spectrometry to develop a simple and sensitive hyphenated method for the determination of aqueous Hg(2+) and MeHg(+) species. The separation of Hg(2+) and MeHg(+) was accomplished on a cation-exchange guard column using a glutathione (GSH)-containing eluent. To achieve optimal chromatographic separation and signal intensities, we investigated the influence of several of the operating parameters of the chromatographic and photocatalyst-assisted VG systems. Under the optimized conditions of VG process, the shortcomings of conventional SnCl(2)-based VG techniques for the vaporization of MeHg(+) was overcome; comparing to the concentric nebulizer-ICP-MS system, the analytical sensitivity of ICP-MS toward the detection of Hg(2+) and MeHg(+) were also improved to 25- and 7-fold, respectively. With the use of our established HPLC-UV/nano-TiO(2)-ICP-MS system, the precision for each analyte, based on three replicate injections of 2 ng/mL samples of each species, was better than 15% RSD. This hyphenated method also provided excellent detection limits--0.1 and 0.03 ng/mL for Hg(2+) and MeHg(+), respectively. A series of validation experiments--analysis of the NIST 2672a Standard Urine Reference Material and other urine samples--confirmed further that our proposed method could be applied satisfactorily to the determination of inorganic Hg(2+) and MeHg(+) species in real samples. PMID:19913233

  19. Chemical vapor generation for atomic spectrometry. A contribution to the comprehension of reaction mechanisms in the generation of volatile hydrides using borane complexes

    NASA Astrophysics Data System (ADS)

    D'Ulivo, Alessandro; Baiocchi, Cristiano; Pitzalis, Emanuela; Onor, Massimo; Zamboni, Roberto

    2004-04-01

    A systematic study has been developed in order to clarify the mechanism of hydride generation using different borane complexes [sodium tetrahydroborate(III), NaBH 4 (THB); borane-ammonia complex, H 3B-NH 3 (AB); borane- tert-Butylamine complex, H 3B-NH 2C(CH 3) 3 (TBAB)], as derivatizing reagents. Stannane, stibine and bismuthine were generated in a continuous flow reaction system at different acidities in the pH range of 1.38-12.7. The pH of sample solution was pre-equilibrated on-line in a mixing loop by the addition of appropriate solution before the reaction with the derivatizing reagent in a reaction loop. The generated hydrides were delivered to a miniature argon hydrogen flame atomizer and free atoms detected by atomic absorption spectrometry (AAS). The effect of pH on the relative sensitivity has been investigated by varying both the mixing loop volume (4, 15 and 50 μl) and reaction loop volume (100 and 500 μl). The mixing rates of the solutions have been also tested to avoid any undesired effect arising from the incomplete mixing of the solution in the flow reaction system. The generation of hydrides using on-line pre-equilibration of pH can be observed also in alkaline or neutral conditions, while the generation of the same hydrides is observed only in acidic solution if the equilibration of pH was performed off-line. Stannane generation using amineboranes has never been reported before. Kinetic calculations were performed in order to estimate the concentration of nascent hydrogen arising from the decomposition of the derivatizing agents in the flow reaction system. It has been found that in many cases, the mechanism of nascent hydrogen failed to explain the generation of the hydrides. The direct action of BH 4- and H 3B-X species (X=ammonia or amino group) on the analyte element, present in solution in a suitable chemical form, is the only possible mechanism of hydride formation in a wide range of solution acidities, from pH 4.5 up to pH 12.7. The

  20. Statistical mechanics of sum frequency generation spectroscopy for the liquid-vapor interface of dilute aqueous salt solutions

    SciTech Connect

    Noah-Vanhoucke, Joyce; Smith, Jared D.; Geissler, Phillip L.

    2009-01-02

    We demonstrate a theoretical description of vibrational sum frequency generation (SFG) at the boundary of aqueous electrolyte solutions. This approach identifies and exploits a simple relationship between SFG lineshapes and the statistics of molecular orientation and electric field. Our computer simulations indicate that orientational averages governing SFG susceptibility do not manifest ion-specific shifts in local electric field, but instead, ion-induced polarization of subsurface layers. Counterbalancing effects are obtained for monovalent anions and cations at the same depth. Ions held at different depths induce an imbalanced polarization, suggesting that ion-specific effects can arise from weak, long ranged influence on solvent organization.

  1. Direct determination of arsenic in soil samples by fast pyrolysis-chemical vapor generation using sodium formate as a reductant followed by nondispersive atomic fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Duan, Xuchuan; Zhang, Jingya; Bu, Fanlong

    2015-09-01

    This new study shows for the first time that sodium formate can react with trace arsenic to form volatile species via fast pyrolysis - chemical vapor generation. We found that the presence of thiourea greatly enhanced the generation efficiency and eliminated the interference of copper. We studied the reaction temperature, the volume of sodium formate, the reaction acidity, and the carried argon rate using nondispersive atomic fluorescence spectrometry. Under optimal conditions of T = 500 °C, the volumes of 30% sodium formate and 10% thiourea were 0.2 ml and 0.05 ml, respectively. The carrier argon rate was 300 ml min- 1 and the detection limit and precision of arsenic were 0.39 ng and 3.25%, respectively. The amount of arsenic in soil can be directly determined by adding trace amount of hydrochloric acid as a decomposition reagent without any sample pretreatment. The method was successfully applied to determine trace amount of arsenic in two soil-certified reference materials (GBW07453 and GBW07450), and the results were found to be in agreement with certified reference values.

  2. Novel chemical vapor deposition process of ZnO films using nonequilibrium N2 plasma generated near atmospheric pressure with small amount of O2 below 1%

    NASA Astrophysics Data System (ADS)

    Nose, Yukinori; Yoshimura, Takeshi; Ashida, Atsushi; Uehara, Tsuyoshi; Fujimura, Norifumi

    2016-05-01

    We propose a novel chemical vapor deposition (CVD) process of ZnO films involving a nonequilibrium N2 plasma generated near atmospheric pressure with small O2 concentration (O2%) below 1%. In the optical emission (OE) spectra of the plasma, OE lines corresponding to the NO-γ system ( A 2 Σ + → X 2 Πγ + ) were observed, despite the only introduced gases being N2 and O2; these vanish at an O2% of more than 1%. ZnO films were grown on a glass substrate placed in the plasma at a growth temperature of as low as 200 °C and at an O2% of below 1% in the presence of the NO-γ system. This plasma yielded almost the same growth rate for ZnO films as O2 plasma including atomic O radicals that are often observed in low-pressure O2 plasma, suggesting that some highly reactive oxidant was sufficiently generated in such a small O2%. ZnO films synthesized using this plasma exhibited excellent ( 0001 ) preferred orientation without other diffractions such as 10 1 ¯ 1 diffraction, and with an optical bandgap of 3.30 eV. Based on the analyses of the plasma and the exhaust gases, the coexistence state of NO-γ and O3 should be essential and useful for the decomposition and oxidation of Zn source material in the proposed CVD process.

  3. Ultraviolet vapor generation atomic fluorescence spectrometric determination of mercury in natural water with enrichment by on-line solid phase extraction

    NASA Astrophysics Data System (ADS)

    Qin, Deyuan; Gao, Feng; Zhang, Zhaohui; Zhao, Liqian; Liu, Jixin; Ye, Jianping; Li, Junwei; Zheng, Fengxi

    2013-10-01

    A novel method, which coupled an on-line solid phase extraction (SPE) enrichment with ultraviolet vapor generation (UVG) atomic fluorescence spectrometry (AFS), was developed to improve the sensitivity of mercury determination and to remove the interference of some anion and organics to UVG of mercury. A high mercury retention efficiency and maximum exclusion of inorganic and organic matrix in water samples were achieved by using C18 SPE mini cartridge modified with sodium diethyldithiocarbamate (DDTC). Fast and efficient elution from the cartridge was found by using L-cysteine mixing solution. Furthermore, through the investigation of different UV reactor designs, the most important factor was the structure of the reactor (which corresponded roughly to the photon flux) wherein the tubing was sintered into the UV lamp to give the highest UV generation efficiency. The second factor was the materials of the tubing (which roughly corresponded to the working wavelength). Synthetic quartz, characterized by the highest transparency at 185 nm, attained the highest UVG efficiency, suggesting that the most favorable wavelength for UVG was 185 nm. Under optimum conditions, the achievable detection limit (3σ) with sample loadings of 10.0 mL was 0.03 ng L- 1 and 0.08 ng L- 1 with different manifolds, respectively. The method was successfully applied to the determination of Hg in tap water, river water and lake water samples.

  4. Dynamic Electrothermal Model of a Sputtered Thermopile Thermal Radiation Detector for Earth Radiation Budget Applications

    NASA Technical Reports Server (NTRS)

    Weckmann, Stephanie

    1997-01-01

    The Clouds and the Earth's Radiant Energy System (CERES) is a program sponsored by the National Aeronautics and Space Administration (NASA) aimed at evaluating the global energy balance. Current scanning radiometers used for CERES consist of thin-film thermistor bolometers viewing the Earth through a Cassegrain telescope. The Thermal Radiation Group, a laboratory in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently studying a new sensor concept to replace the current bolometer: a thermopile thermal radiation detector. This next-generation detector would consist of a thermal sensor array made of thermocouple junction pairs, or thermopiles. The objective of the current research is to perform a thermal analysis of the thermopile. Numerical thermal models are particularly suited to solve problems for which temperature is the dominant mechanism of the operation of the device (through the thermoelectric effect), as well as for complex geometries composed of numerous different materials. Feasibility and design specifications are studied by developing a dynamic electrothermal model of the thermopile using the finite element method. A commercial finite element-modeling package, ALGOR, is used.

  5. Experimental Studies of the Electrothermal and Magneto-Rayleigh Taylor Instabilities on Thin Metal Foil Ablations

    NASA Astrophysics Data System (ADS)

    Steiner, Adam; Yager-Elorriaga, David; Patel, Sonal; Jordan, Nicholas; Gilgenbach, Ronald; Lau, Y. Y.

    2015-11-01

    The electrothermal instability (ETI) and magneto-Rayleigh Taylor instability (MRT) are important in the implosion of metallic liners, such as magnetized liner implosion fusion (MagLIF). The MAIZE linear transformer driver (LTD) at the University of Michigan generates 200 ns risetime-current pulses of 500 to 600 kA into Al foil liners to study plasma instabilities and implosion dynamics, most recently MRT growth on imploding cylindrical liners. A full circuit model of MAIZE, along with I-V measurements, yields time-resolved load inductance. This has enabled measurements of an effective current-carrying radius to determine implosion velocity and plasma-vacuum interface acceleration. Measurements are also compared to implosion data from 4-time-frame laser shadowgraphy. Improved resolution measurements on the laser shadowgraph system have been used to examine the liner interface early in the shot to examine surface perturbations resulting from ETI for various seeding conditions. Fourier analysis examines the growth rates of wavelength bands of these structures to examine the transition from ETI to MRT. This work was supported by the U.S. DoE through award DE-SC0012328. S.G. Patel is supported by Sandia National Labs. D.A. Yager is supported by NSF fellowship grant DGE 1256260.

  6. A review of research and development on the microwave-plasma electrothermal rocket

    NASA Technical Reports Server (NTRS)

    Hawley, Martin C.; Asmussen, Jes; Filpus, John W.; Frasch, Lydell L.; Whitehair, Stanley; Morin, T. J.; Chapman, R.

    1987-01-01

    The microwave-plasma electrothermal rocket (MWPETR) shows promise for spacecraft propulsion and maneuvering, without some of the drawbacks of competitive electric propulsion systems. In the MWPETR, the electric power is first converted to microwave-frequency radiation. In a specially-designed microwave cavity system, the electromagnetic energy of the radiation is transferred to the electrons in a plasma sustained in the working fluid. The resulting high-energy electrons transfer their energy to the atoms and molecules of the working fluid by collisions. The working fluid, thus heated, expands through a nozzle to generate thrust. In the MWPETR, no electrodes are in contact with the working fluid, the energy is transferred into the working fluid by nonthermal mechanisms, and the main requirement for the materials of construction is that the walls of the plasma chamber be insulating and transparent to microwave radiation at operating conditions. In this survey of work on the MWPETR, several experimental configurations are described and compared. Diagnostic methods used in the study are described and compared, including titration, spectroscopy, calorimetry, electric field measurements, gas-dynamic methods, and thrust measurements. Measured and estimated performance efficiencies are reported. Results of computer modeling of the plasma and of the gas flowing from the plasma are summarized.

  7. Review of research and development on the microwave-plasma electrothermal rocket

    SciTech Connect

    Hawley, M.C.; Asmussen, J.; Filpus, J.W.; Frasch, L.L.; Whitehair, S.

    1987-01-01

    The microwave-plasma electrothermal rocket (MWPETR) shows promise for spacecraft propulsion and maneuvering, without some of the drawbacks of competitive electric propulsion systems. In the MWPETR, the electric power is first converted to microwave-frequency radiation. In a specially-designed microwave cavity system, the electromagnetic energy of the radiation is transferred to the electrons in a plasma sustained in the working fluid. The resulting high-energy electrons transfer their energy to the atoms and molecules of the working fluid by collisions. The working fluid, thus heated, expands through a nozzle to generate thrust. In the MWPETR, no electrodes are in contact with the working fluid, the energy is transferred into the working fluid by nonthermal mechanisms, and the main requirement for the materials of construction is that the walls of the plasma chamber be insulating and transparent to microwave radiation at operating conditions. In this survey of work on the MWPETR, several experimental configurations are described and compared. Diagnostic methods used in the study are described and compared, including titration, spectroscopy, calorimetry, electric field measurements, gas-dynamic methods, and thrust measurements. Measured and estimated performance efficiencies are reported. Results of computer modeling of the plasma and of the gas flowing from the plasma are summarized. 32 references.

  8. Electrothermal piezoresistive cantilever resonators for personal measurements of nanoparticles in workplace exposure

    NASA Astrophysics Data System (ADS)

    Wasisto, Hutomo Suryo; Wu, Wenze; Uhde, Erik; Waag, Andreas; Peiner, Erwin

    2015-05-01

    Low-cost and low-power piezoresistive cantilever resonators with integrated electrothermal heaters are developed to support the sensing module enhancement of the second generation of handheld cantilever-based airborne nanoparticle (NP) detector (CANTOR-2). These sensors are used for direct-reading of exposure to carbon engineered nanoparticles (ENPs) at indoor workplaces. The cantilever structures having various shapes of free ends are created using silicon bulk micromachining technologies (i.e, rectangular, hammer-head, triangular, and U-shaped cantilevers). For a complete wearable CANTOR-2, all components of the proposed detector can be grouped into two main units depending on their packaging placements (i.e., the NP sampler head and the electronics mounted in a handy-format housing). In the NP sampler head, a miniaturized electrophoretic aerosol sampler and a resonant silicon cantilever mass sensor are employed to collect the ENPs from the air stream to the cantilever surfaces and measuring their mass concentration, respectively. After calibration, the detected ENP mass concentrations of CANTOR-2 show a standard deviation from fast mobility particle sizer (FMPS, TSI 3091) of 8-14%.

  9. Study on an alternating current electrothermal micropump for microneedle-based fluid delivery systems

    NASA Astrophysics Data System (ADS)

    Zhang, Rumi; Jullien, Graham A.; Dalton, Colin

    2013-07-01

    In this paper, we report on a modeling study of an AC electrothermal (ACET) micropump with high operating pressures as well as fast flow rates. One specific application area is for fluid delivery using microneedle arrays which require higher pressures and faster flow rates than have been previously reported with ACET devices. ACET is very suitable for accurate actuation and control of fluid flow, since the technique has been shown to be very effective in high conductivity fluids and has the ability to create a pulsation free flow. However, AC electrokinetic pumps usually can only generate low operating pressures of 1 to 100 Pa, where flow reversal is likely to occur with an external load. In order to realize a high performance ACET micropump for continuous fluid delivery, applying relatively high AC operating voltages (20 to 36 Vrms) to silicon substrate ACET actuators and using long serpentine channel allows the boosting of operating pressure as well as increasing the flow rates. Fast pumping flow rates (102-103 nl/s) and high operating pressures (1-12 kPa) can be achieved by applying both methods, making them of significant importance for continuous fluid delivery applications using microneedle arrays and other such biomedical devices.

  10. Optimisation of air cooled, open-cathode fuel cells: Current of lowest resistance and electro-thermal performance mapping

    NASA Astrophysics Data System (ADS)

    Meyer, Quentin; Ronaszegi, Krisztian; Pei-June, Gan; Curnick, Oliver; Ashton, Sean; Reisch, Tobias; Adcock, Paul; Shearing, Paul R.; Brett, Daniel J. L.

    2015-09-01

    Selecting the ideal operating point for a fuel cell depends on the application and consequent trade-off between efficiency, power density and various operating considerations. A systematic methodology for determining the optimal operating point for fuel cells is lacking; there is also the need for a single-value metric to describe and compare fuel cell performance. This work shows how the 'current of lowest resistance' can be accurately measured using electrochemical impedance spectroscopy and used as a useful metric of fuel cell performance. This, along with other measures, is then used to generate an 'electro-thermal performance map' of fuel cell operation. A commercial air-cooled open-cathode fuel cell is used to demonstrate how the approach can be used; in this case leading to the identification of the optimum operating temperature of ∼45 °C.