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1

Laboratory studies of the behavior of undissolved solids in both pulsed and packed column extraction systems  

SciTech Connect

A substantial fraction of the finely divided undissolved solid material found in nuclear fuel reprocessing dissolver-product solutions is hydrophobic and tends to seek'' any organic-aqueous interface existing within countercurrent liquid-liquid extraction systems. While passing through pulsed-type columns this material is swept out of the aqueous phase by the combined surface area of the tiny bubbles of dispersed phase. Because these bubbles have a net velocity towards the end of the column where the nominal interface is located, the solids are swept in that direction too. These solids tend to gather in a three-phase crud'' layer at the nominal interface point. At equilibrium, about the same amount breaks off from the crud layer and escapes into the liquid exiting from that end of the column as enters it from the other side. If large enough, the crud layer can even interfere with interface detection and control equipment. In packed-column extraction systems, an additional problem is that feed solids can accumulate within the packing material to the point that the column floods'' or even totally plugs. The keys to preventing solids-related problems is the correct choice of interface level, and with packed columns, the addition of a pulsing leg'' at the bottom of the column. Pulsing packed column systems not only prevents solids from settling onto packing material but it also increses the number of theoretical stages available for extraction. 3 figs., 2 tabs.

Siemer, D.D.

1989-04-18

2

Laboratory studies of the behavior of undissolved solids in both pulsed and packed column extraction systems  

SciTech Connect

A substantial fraction of the finely divided undissolved solid material found in nuclear fuel reprocessing dissolver-product solutions is hydrophobic and tends to ``seek`` any organic-aqueous interface existing within countercurrent liquid-liquid extraction systems. While passing through pulsed-type columns this material is swept out of the aqueous phase by the combined surface area of the tiny bubbles of dispersed phase. Because these bubbles have a net velocity towards the end of the column where the nominal interface is located, the solids are swept in that direction too. These solids tend to gather in a three-phase ``crud`` layer at the nominal interface point. At equilibrium, about the same amount breaks off from the crud layer and escapes into the liquid exiting from that end of the column as enters it from the other side. If large enough, the crud layer can even interfere with interface detection and control equipment. In packed-column extraction systems, an additional problem is that feed solids can accumulate within the packing material to the point that the column `` floods`` or even totally plugs. The keys to preventing solids-related problems is the correct choice of interface level, and with packed columns, the addition of a ``pulsing leg`` at the bottom of the column. Pulsing packed column systems not only prevents solids from settling onto packing material but it also increses the number of theoretical stages available for extraction. 3 figs., 2 tabs.

Siemer, D.D.

1989-04-18

3

Study on the dynamic holdup distribution of the pulsed extraction column  

SciTech Connect

In the study, a CSTR cascade dynamic hydraulic model was developed to investigate the dynamic holdup distribution of the pulsed extraction column. It is assumed that the dynamic process of the dispersed phase holdup of pulsed extraction column has equal effects with the operational process of multiple cascade CSTRs. The process is consistent with the following assumptions: the holdups vary on different stages but maintain uniform on each stage; the changes of the hydraulic parameters have impact initially on the inlet of dispersed phase, and stability will be reached gradually through stage-by-stage blending. The model was tested and verified utilizing time domain response curves of the average holdup. Nearly 150 experiments were carried out with different capillary columns, various feed liquids, and diverse continuous phases and under different operation conditions. The regression curves developed by the model show a good consistency with the experimental results. After linking parameters of the model with operational conditions, the study further found that the parameters are only linearly correlated with pulse conditions and have nothing to do with flow rate for a specific pulsed extraction column. The accuracy of the model is measured by the average holdup, and the absolute error is ±0.01. The model can provide supports for the boundary studies on hydraulics and mass transfer by making simple and reliable prediction of the dynamic holdup distribution, with relatively less accessible hydraulic experimental data. (authors)

Wang, S.; Chen, J.; Wu, Q. [Tsinghua University, Beijing 100084 (China)

2013-07-01

4

GAMMA DENSITY CONTROLS EXTRACTION COLUMN  

Microsoft Academic Search

Gamma absorption density gauging can monitor both the organic extract ; and the aqueous raffinate and can control column feed rates to maintain normal ; steadystate operation in a liquid-liquid uranium extraction process. (auth);

Ryle

1957-01-01

5

Installation of the Pulse-Plate Column Pilot Plant  

SciTech Connect

There are three primary types of solvent extraction equipment utilized in the nuclear industry for reprocessing of used nuclear fuel; pulse columns, mixer-settlers, and centrifugal contactors. Considerable research and development has been performed at the INL and throughout the DOE complex on the application of centrifugal contactors for used fuel reprocessing and these contactors offer many significant advantages. However, pulse columns have been used extensively in the past in throughout the world for aqueous separations processes and remain the preferred equipment by many commercial entities. Therefore, a pulse-plate column pilot plant has been assembled as part of the Advanced Fuel Cycle Initiative to support experimentation and demonstration of pulse column operation. This will allow the training of personnel in the operation of pulse columns. Also, this capability will provide the equipment to allow for research to be conducted in the operation of pulse columns with advanced solvents and processes developed as part of the fuel cycle research and development being performed in the AFCI program.

Nick R. Mann

2009-07-01

6

Evaluation of Packed Columns in Supercritical Extraction Processes  

E-print Network

--------- EVALUATION OF PACKED COLUMNS IN SUPERCRITICAL EXTRACTION PROCESSES Paul J. Rathkamp, James R. Fair, Jimmy L. Humphrey The University of Texas at Austin Austin, Texas ABSTRACT The purpose of the present work is to add to the base... of knowledge in the use of packed columns when used in supercritical extraction service. Ex perimental studies were performed on a one-inch di ameter supercritical fluid extraction column oper ated in both spray and packed column arrangements. The packing...

Rathkamp, P. J.; Fair, J. R.; Humphrey, J. L.

7

Rapid Column Extraction Methods for Urine  

SciTech Connect

A new fecal analysis method that dissolves plutonium oxide was developed at the Westinghouse Savannah River Site. Diphonix Resin (Eichrom Industries), is used to pre-concentrate the actinides from digested fecal samples. A rapid microwave digestion technique is used to remove the actinides from the Diphonix Resin, which effectively extracts plutonium and americium from acidic solutions containing hydrofluoric acid. After resin digestion, the plutonium and americium are recovered in a small volume of nitric acid that is loaded onto small extraction chromatography columns, TEVA Resin and TRU Resin (Eichrom Industries). The method enables complete dissolution of plutonium oxide and provides high recovery of plutonium and americium with good removal of thorium isotopes such as thorium-228.

Maxwell, S.L. III

2000-06-09

8

Comparison of predicted and measured pulsed-column profiles and inventories  

SciTech Connect

Nuclear materials accounting and process control in fuels reprocessing plants can be improved by near-real-time estimation of the in-process inventory in solvent-extraction contactors. Experimental studies were conducted on pilot- and plant-scale pulsed columns by Allied-General Nuclear Service (AGNS), and the extensive uranium concentration-profile and inventory data were analyzed by Los Alamos and AGNS to develop and evaluate different predictive inventory techniques. Preliminary comparisons of predicted and measured pulsed-column profiles and inventories show promise for using these predictive techniques to improve nuclear materials accounting and process control in fuels reprocessing plants.

Ostenak, C.A.; Cermak, A.F.

1983-01-01

9

SNS EXTRACTION FAST KICKER PULSED POWER SYSTEM  

Microsoft Academic Search

The Spallation Neutron Source (SNS) is a next generation high intensity beam facility. The extraction kicker system is a high peak power, high average power, high precision pulse-waveform, low beam impedance, and high repetition rate pulsed power system. It has been successfully design and developed at Brookhaven National Laboratory. The system consists of fourteen extraction magnet sections inside the ring

W. Zhang; J. Sandberg; H. Hahn; C. Pai; Y. Tan; N. Tsoupas; J. Tuozzolo; D. Warburton; J. Wei; K. Rust; R. Cutler

2004-01-01

10

Retrievals of column CO2 mixing ratio from airborne pulsed lidar measurements  

NASA Astrophysics Data System (ADS)

We will present retrieved CO2 column densities from in-flight lidar measurements. We will describe a retrieval algorithm, which extracts the column-average CO2 volume-mixing ratio from pulsed airborne lidar measurements. The airborne instrument steps a pulsed wavelength-tunable laser transmitter across the 1572.33 nm CO2 line in twenty steps at a 450 Hz repitition rate. The laser beam is co-aligned with the receiver and directed toward nadir. The energy of the laser echoes from land and water surfaces are measured. The gas extinction and column densities for the CO2 are obtained from a retrieval algorithm that fits the observed scan while accounting for atmospheric temperature, pressure, water vapor and the lidar’s wavelength response During summer 2009 we flew the instrument on the NASA Glenn LearJet-25 aircraft over a variety of surface types: corn and soybean fields of the US Midwest, the Oklahoma prairie and waters of the Chesapeake Bay. At selected locations we flew stair step patterns at altitudes from 4 to 12 km. At the Oklahoma site the flights were also coordinated with DOE investigators who flew their in-situ CO2 sensor on a Cessna aircraft inside the LearJet flight pattern. We will present the lidar retrieved CO2 column amounts from the in-flight measurements along side in-situ measurements where available.

Weaver, C. J.; Allan, G. R.; Riris, H.; Hasselbrack, W. E.; Biraud, S.; Abshire, J. B.

2009-12-01

11

Pulsed Airborne Lidar Measurements of C02 Column Absorption  

NASA Technical Reports Server (NTRS)

We report on airborne lidar measurements of atmospheric CO2 column density for an approach being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO2 measurement from aircraft in July and August 2009 over four locations. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The 2009 measurements have been analyzed in detail and the results show approx.1 ppm random errors for 8-10 km altitudes and approx.30 sec averaging times. Airborne measurements were also made in 2010 with stronger signals and initial analysis shows approx. 0.3 ppm random errors for 80 sec averaging times for measurements at altitudes> 6 km.

Abshire, James B.; Riris, Haris; Allan, Graham R.; Weaver, Clark J.; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William E.; Rodriquez, Michael; Browell, Edward V.

2011-01-01

12

Rapid Column Extraction method for SoilRapid Column Extraction method for Soil  

SciTech Connect

The analysis of actinides in environmental soil and sediment samples is very important for environmental monitoring as well as for emergency preparedness. A new, rapid actinide separation method has been developed and implemented that provides total dissolution of large soil samples, high chemical recoveries and effective removal of matrix interferences. This method uses stacked TEVA Resin{reg_sign}, TRU Resin{reg_sign} and DGA-Resin{reg_sign} cartridges from Eichrom Technologies (Darien, IL, USA) that allows the rapid separation of plutonium (Pu) neptunium (Np), uranium (U), americium (Am), and curium (Cm) using a single multi-stage column combined with alpha spectrometry. The method combines a rapid fusion step for total dissolution to dissolve refractory analytes and matrix removal using cerium fluoride precipitation to remove the difficult soil matrix. By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized.

Maxwell, Sherrod, L. III; Culligan, Brian K.

2005-11-07

13

Development and testing of a rotary disc pulser for pulse column application  

SciTech Connect

Air pulse column contactors are a favored method of conducting radiochemical liquid-liquid separations processes. They have no moving parts and are easily operated from behind thick shielding. A ruggedly constructed more reliable air pulsing device was developed and its operation mathematically characterized in this study. Additionally, a correlation for the column perforated nozzle plate discharge coefficient was developed. Rigorous mass, momentum, and energy balances were solved using a computer software code entitled ''Advanced Continuous Simulation Language.'' Experimental data from a 2-inch diameter glass column equipped with the prototypical air pulser showed that column pulse amplitudes could be predicted within 10% for the conditions studied and within 5% for normal column operating conditions. 17 refs., 45 figs., 15 tabs.

Olson, A.L.

1988-10-01

14

Determination of radiostrontium in milk using an extraction chromatography column  

SciTech Connect

Analyses of {sup 89}Sr and {sup 90}Sr in milk samples are improved by using an extraction chromatography column to isolate strontium. Following ingrowth of {sup 90}Y, strontium and yttrium are separately precipitated and weighed for chemical yield. The precipitates are analyzed separately on low-level beta counters. Detection limits below 1 pCi/L are obtained using 1-liter samples. The method exhibits an accuracy of 96% (defined as the average of results/expected values) and a precision of 6% (standard deviation/average) for milk samples spiked with {sup 90}Sr. The same accuracy (96%) but less favorable precision (15%) have been obtained with {sup 89}Sr-spiked samples, caused by shorter counting intervals and by the interaction of {sup 90}Sr spike used in the same samples.

Jeter, H.W. [Teledyne Brown Engineering, Westwood, NJ (United States); Grob, B. [Teledyne Brown Engineering, Northbrook, IL (United States)

1994-12-31

15

Cavity Optical Pulse Extraction: ultra-short pulse generation as seeded Hawking radiation  

PubMed Central

We show that light trapped in an optical cavity can be extracted from that cavity in an ultrashort burst by means of a trigger pulse. We find a simple analytic description of this process and show that while the extracted pulse inherits its pulse length from that of the trigger pulse, its wavelength can be completely different. Cavity Optical Pulse Extraction is thus well suited for the development of ultrashort laser sources in new wavelength ranges. We discuss similarities between this process and the generation of Hawking radiation at the optical analogue of an event horizon with extremely high Hawking temperature. Our analytic predictions are confirmed by thorough numerical simulations. PMID:24060831

Eilenberger, Falk; Kabakova, Irina V.; de Sterke, C. Martijn; Eggleton, Benjamin J.; Pertsch, Thomas

2013-01-01

16

Genomic DNA extraction protocols for bone samples: The comparison of Qiagen and Zymo Research spin columns  

Microsoft Academic Search

The aim of this study was to develop an extraction protocol for bone samples based on ZR Genomic DNA Tissue MicroPrep kit and perform a quantitative comparison with the existing silica extraction protocol based on Qiagen columns and evaluate the effect of demineralization on the quantity of extracted DNA.

Daniel Vanek; Marcela Silerova; Vladislava Urbanova; Lenka Saskova; Jitka Dubska; Michal Beran

17

Extreme degree of ionization in micro-capillary plasma columns heated by ultrafast current pulses  

NASA Astrophysics Data System (ADS)

The efficient generation of dense large-scale plasma columns with very high degree of ionization and high homogeneity can enable fundamental plasma studies and a variety of promising applications. We demonstrate the generation of dense large-aspect-ratio plasmas columns with extremely high degree of ionization in micro-capillary channels heated by ultrafast discharge current pulses. Xenon plasma columns were ionized to the Co-like stage (Xe XXVIII) injecting 37 kA current pulses with 4 ns risetime into of 500 micrometer diameter, with lines from the Fe-like ion (Xe XXIX) also visible in the spectra. Sequences of time-resolved filtered pinhole images of the plasma column show a symmetric compression leading to 300: 1 aspect-ration plasma channels. The experimental results, that include ionization of Al impurities up to the H-like stage, support model simulations in showing that rapid ohmic heating of micro-capillary channels with relatively modest currents can generate very hot dense plasma columns which electron temperature could approach 1 KeV.

Rocca, Jorge; Li, Jing; Avaria, Gonzalo; Grisham, Michael; Tomasel, Fernando; Shlyaptsev, Vyacheslav

2012-10-01

18

Solid-phase extraction of plant thionins employing aluminum silicate based extraction columns.  

PubMed

Thionins belong to a family of cysteine-rich, low-molecular-weight (?5 KDa) biologically active proteins in the plant kingdom. They display a broad cellular toxicity against a wide range of organisms and eukaryotic cell lines. Thionins protect plants against different pathogens, including bacteria and fungi. A highly selective solid-phase extraction method for plant thionins is reported deploying aluminum silicate (3:2 mullite) powder as a sorbent in extraction columns. Mullite was shown to considerably improve selectivity compared to a previously described zirconium silicate embedded poly(styrene-co-divinylbenzene) monolithic polymer. Due to the presence of aluminum(III), mullite offers electrostatic interactions for the selective isolation of cysteine-rich proteins. In comparison to zirconium(IV) silicate, aluminum(III) silicate showed reduced interactions towards proteins which resulted into superior washings of unspecific compounds while still retaining cysteine-rich thionins. In the presented study, European mistletoe, wheat and barley samples were subjected to solid-phase extraction analysis for isolation of viscotoxins, purothionins and hordothionins, respectively. Matrix-assisted laser desorption/ionization time of flight mass spectroscopy was used for determining the selectivity of the sorbent toward thionins. The selectively retained thionins were quantified by colorimetric detection using the bicinchoninic acid assay. For peptide mass-fingerprint analysis tryptic digests of eluates were examined. PMID:24913248

Hussain, Shah; Güzel, Yüksel; Pezzei, Cornelia; Rainer, Matthias; Huck, Christian W; Bonn, Günther K

2014-08-01

19

Uranium concentration profile along the pulsed column: its determination and importance with regard to solute's accountability  

SciTech Connect

Considerable interest has been shown in recent years in developing reliable nuclear materials accounting systems for enriched uranium and plutonium in nuclear fuel reprocessing plants. This paper discusses a method which utilizes the experimental (or computed) solute concentration profiles and dispersed phase holdup values within the contactor. The method was developed using uranium inventory data from Barnwell Nuclear Fuel Plant (BNFP) pilot-scale pulsed columns.

Cermak, A.F.

1983-08-01

20

High-density lithium plasma columns generated by intense subpicosecond KrF laser pulses  

Microsoft Academic Search

Subpicosecond KrF laser pulses were focused with an intensity of 2×1015 W\\/cm2 to a traveling-wave line-focus on solid lithium targets to create a 3 ?m wide plasma column of up to 800 ?m length. The soft X-ray emission between 1 nm and 15 nm of the laser produced plasma was measured in both longitudinal and transversal directions to the plasma

W. Theobald; C. Wülker; J. Jasny; J. S Bakos; J. Jethwa; F. P Schäfer

1998-01-01

21

Power extraction from an oscillating water column along a coast  

E-print Network

For reasons of wave climate, geography, construction, maintenance, energy storage and transmission, some devices for extracting energy from sea waves will likely be installed on the coast. We study here the specific case ...

Martins-rivas, Hervé

2008-01-01

22

Mass transfer in countercurrent packed columns: Application to supercritical CO[sub 2] extraction of terpenes  

SciTech Connect

Supercritical fluid extraction (SFE) is an alternative separation method to more conventional processes such as liquid extraction and distillation. However, up to now, few works have been devoted to the investigation of the efficiency of countercurrent packed columns under supercritical conditions from a mass transfer point of view. Mass transfer in a countercurrent column, filled with structured gauze packing, was measured for the separation of a mixture of terpenes (d-limonene/1,8-cineole) by supercritical carbon dioxide, at 313 and 318 K and pressures up to 9 MPa. The extraction efficiency was determined in terms of the overall mass transfer coefficient. Operating lines for this process had an appreciable curvature due to a high miscibility of the two contacting phases. The real slope of these lines had to be estimated. Available mass transfer models for packed columns predicted efficiencies diverging to a great extent from the experimental results.

Simoes, P.C.; Matos, H.A.; Carmelo, P.J.; Gomes de Azevedo, E.; Nunes da Ponte, M. (Univ. Nova de Lisboa, Monte de Caparica (Portugal). Faculdade de Ciencias e Tecnologia)

1995-02-01

23

Extraction of negative ions from pulsed electronegative capacitively coupled plasmas  

NASA Astrophysics Data System (ADS)

Charge buildup during plasma etching of dielectric features can lead to undesirable effects, such as notching, bowing, and twisting. Pulsed plasmas have been suggested as a method to achieve charge-free plasma etching. In particular, electronegative plasmas are attractive as the collapse of the plasma potential during the after-glow period of pulsed capacitively coupled plasmas (CCPs) can allow for extraction of negative ions into the feature. The extraction of negative ions in the after-glow of pulsed CCPs sustained in CF4 containing gas mixtures is computationally investigated. In this paper, the consequences of pulse frequency and gas chemistry on negative ion flux to the wafer are discussed. A low negative ion flux to the wafer was observed only in the late after-glow period of low pulse frequencies. The negative ion flux was found to significantly increase with the addition of highly electronegative gases (such as thermally attaching Cl2) even at a high pulse frequency of 10 kHz. As the production of negative ions during the after-glow diminishes, alternative strategies to enhance the flux were also pursued. The flux of negative ions was found to increase by the addition of a pulsed dc voltage on the top electrode that is 180° out-of-phase with the rf pulse.

Agarwal, Ankur; Rauf, Shahid; Collins, Ken

2012-08-01

24

Airborne Measurements of Atmospheric Methane Column Abundance Made Using a Pulsed IPDA Lidar  

NASA Technical Reports Server (NTRS)

We report airborne measurements of the column abundance of atmospheric methane made over an altitude range of 3-11 km using a direct detection IPDA lidar with a pulsed laser emitting at 1651 nm. The laser transmitter was a tunable, seeded optical parametric amplifier (OPA) pumped by a Nd:YAG laser and the receiver used a photomultiplier detector and photon counting electronics. The results follow the expected changes with aircraft altitude and the measured line shapes and optical depths show good agreement with theoretical calculations.

Riris, Haris; Numata, Kenji; Li, Steve; Wu, Stewart; Ramanathan, Anamd; Dawsey, Martha; Mao, Jianping; Kawa, Randolph; Abshire, James B.

2012-01-01

25

Grid-controlled extraction of pulsed ion beams  

NASA Astrophysics Data System (ADS)

Experimental results are presented on a method for extracting well-focused ion beams from plasma sources with time-varying properties. An electrostatic grid was used to stop the flow of plasma electrons so that only ions entered the extraction gap. In this case, ion flow in the gap was controlled by space-charge effects as it would be with a thermionic ion source. Constant extracted current was observed even with large variations of source flux. An insulator spark source and a metal-vapor vacuum arc were used to generate pulsed ion beams. With a hydrocarbon spark, current densities of 44 mA/cm2 were achieved at 20-kV extractor voltage for an 8-?s pulse. With an aluminum-vapor arc, a current density of 15 mA/cm2 (0.3 A total) was measured for a 50-?s pulse.

Humphries, S., Jr.; Burkhart, C.; Coffey, S.; Cooper, G.; Len, L. K.; Savage, M.; Woodall, D. M.; Rutkowski, H.; Oona, H.; Shurter, R.

1986-03-01

26

Experimental study of a drifting low temperature plasma extracted from a magnetized plasma column  

Microsoft Academic Search

In a new divertor simulator, a very cold recombining plasma is produced after transverse electric extraction from a dense magnetized plasma column. The plasma is characterized using probes, spectroscopic measurements, and ultra-fast imaging of spontaneous emission. This new technique is shown to be very useful for the investigation of the recombination processes.

C. Brault; A. Escarguel; Th. Pierre; R. Redon; A. Bois; M. Koubiti; F. Rosmej; R. Stamm; K. Quotb

2006-01-01

27

The Use of an Ionic Liquid in a Karr Reciprocating Plate Extraction Column: Drop Size Distribution  

Microsoft Academic Search

Ionic liquids (ILs) offer a new class of fluids for solvent extraction. This work presents drop size distribution data for the [bmim][PF6]\\/water system and examines the basis of existing drop size prediction models developed for traditional organic\\/aqueous systems in a Karr reciprocating plate column and recommends how they may be used for these new class of materials.

Kelly K. L. Yung; Craig D. Smith; Tim Bowser; Jilska M. Perera; Geoffrey W. Stevens

2012-01-01

28

Pseudospark switch development for the LHC extraction kicker pulse generator  

Microsoft Academic Search

CERN, the European Laboratory for Particle Physics, has started construction of the Large Hadron Collider (LHC), a superconducting accelerator that will collide protons at a center of mass energy of 14 TeV from the year 2005 onwards. The kicker magnet pulse generators of the LHC beam extraction system require fast high power switches. One possible type is the pseudospark switch

L. Ducimetiere; P. Faure; U. Jansson; H. Riege; M. Schlaug; G. H. Schroder; Eugčne B Vossenberg

1996-01-01

29

Extracting heart rate variability from a wearable reflectance pulse oximeter  

Microsoft Academic Search

The effectiveness and efficiency of combat medics can be greatly improved by increasing the speed and precision with which physiological information is gathered from wounded soldiers. In this paper we demonstrate the feasibility of extracting accurate heart rate variability (HRV) measurements from photoplethysmographic (PPG) signals recorded by a reflectance-mode pulse oximeter sensor attached to the forehead.

W. Johnston; Y. Mendelson

2005-01-01

30

Rapid, direct extraction of DNA from soils for PCR analysis using polyvinylpolypyrrolidone spin columns  

Microsoft Academic Search

Polyvinylpolypyrrolidone spin columns were used to rapidly purify crude soil DNA extracts from humic materials for polymerase chain reaction (PCR) analysis. The PCR detection limit for the tfdC gene, encoding chlorocatechol dioxygenase from the 2,4-dichlorophenoxyacetic acid degradation pathway, was 101?102 cells\\/g soil in inoculated soils. The procedure could be applied to the amplification of biodegradative genes from indigenous microbial populations

Marc Berthelet; Lyle G. Whyte; Charles W. Greer

1996-01-01

31

Dynamics of a Finite Liquid Oxygen (LOX) Column in a Pulsed Magnetic Field  

NASA Technical Reports Server (NTRS)

It is well known that liquid oxygen has a sufficient paramagnetic susceptibility that a strong magnetic field gradient can lift it in the earth's gravitational field. The movement of liquid oxygen is vital to the space program since it one of the primary oxidizers used for propulsion. Transport of liquid oxygen (LOX) via direct interaction of the magnetic fields (B field) with the fluid is a current topic of research and development at Kennedy Space Center, FL. This method of transporting (i.e. pumping) LOX may have particular advantages on Mars and other reduced gravitational environments, namely safety and reliability. This paper will address transport of a magnetic fluid, LOX, via phased-pulsed electromagnets acting on the edge of the column of fluid. The authors have developed a physical model from first-principles for the motion of a magnetic fluid in a particular U-tube geometry subjected to a pulsed magnetic field from an arbitrary solenoidal electromagnet. Experimental data that have been collected from the analogous geometry correlate well to that of the ab-initio calculations.

Youngquist, Robert; Immer, Christopher; Lane, John; Simpson, James; Steinrock, T. (Technical Monitor)

2002-01-01

32

The Use of Post-Column Dynamic Ion-Pair Extraction for the Hplc Detection of Anionic Additives in Foods  

Microsoft Academic Search

Applications of post-column ion-pair extraction with absorbance detection to the determination of anionic food additives are discussed. The compounds studied include sodium dioctylsulfosuccinate, artificial sweeteners and free fatty acids. Dyes such as methylene blue and crystal violet provide different extraction and detector wavelength selectivities when used as counter ions. Mobile phase composition, dye concentration; phase ratios and extraction system design

James F. Lawrence

1990-01-01

33

Continuous aqueous two-phase extraction of human antibodies using a packed column.  

PubMed

The performance of a pilot scale packed differential contactor was evaluated for the continuous counter-current aqueous two-phase extraction (ATPE) of human immunoglobulin G (IgG) from a Chinese hamster ovary (CHO) cells supernatant (CS) enriched with pure protein. Preliminary studies have been firstly performed in order to select the dispersed phase (phosphate-rich or polyethylene glycol 3350 Da (PEG)-rich phase) and the column packing material. The PEG-rich phase has been selected as the dispersed phase and the stainless steel as the preferred material for the column packing bed since it was not wetted preferentially by the selected dispersed phase. Hydrodynamic studies have been also performed, and the experimental results were successfully adjusted to the Richardson-Zaki and Mísek equations, typically used for the conventional organic-aqueous two-phase systems. An experimental set-up combining the packed column with a pump mixer-settler stage showed to have the best performance and to be advantageous when compared to the IgG batch extraction. An IgG recovery yield of 85% could be obtained with about 50% of total contaminants and more than 85% of contaminant proteins removal. Mass transfer studies have revealed that the mass transfer was controlled by the PEG-rich phase. A higher efficiency could be obtained when using an extra pump mixer-settler stage and higher flow rates. PMID:22173005

Rosa, P A J; Azevedo, A M; Sommerfeld, S; Bäcker, W; Aires-Barros, M R

2012-01-01

34

Micro-column solid phase extraction to determine uranium and thorium in environmental samples.  

PubMed

Extraction chromatographic separation techniques based on U/TEVA and TEVA resins were utilized to separate uranium and thorium isotopes in complex matrices from environmental samples. This approach has the advantages of ease of quantitative analysis, small sample size, an absence of mixed waste solvents, complete separation of U/Th isotopes, acceptable chemical yields and good energy resolution in the alpha spectrum. The procedure for analyzing alpha-emitting isotopes of uranium and thorium in geothermal water from Peito, Taiwan, is illustrated in detail. It involves sample pre-concentration, filtration and separation by highly selective extraction chromatographic resins, followed by electroplating and alpha-spectroscopy. The analytical results show a chemical recovery exceeding 55% for U and 65% for Th, respectively, under optimized conditions. The efficient and cost-effective use of recyclable columns makes the analytical methods simple, accurate, rapid, reliable and robust. PMID:18430577

Tsai, Tsuey-Lin; Lin, Chun-Chih; Chu, Tieh-Chi

2008-08-01

35

The Use of an Ionic Liquid in a Karr Reciprocating Plate Extraction Column: Dispersed Phase Hold-up Prediction  

Microsoft Academic Search

The use of ionic liquids (ILs) as alternatives to volatile organic liquids in solvent extraction is being considered in a number of applications. This study presents data on the dispersed phase holdup of the ionic liquid [bmim][PF6] with water in a Karr extraction column. It was found that this system conforms to the standard slip velocity relationships and that the

Kelly K. L. Yung; Craig D. Smith; Tim A. Bowser; Jilska M. Perera; Geoffrey W. Stevens

2012-01-01

36

The Use of an Ionic Liquid in a Karr Reciprocating Plate Extraction Column: Dispersed Phase Hold-Up Prediction  

Microsoft Academic Search

The use of ionic liquids (ILs) as alternatives to volatile organic liquids in solvent extraction is being considered in a number of applications. This study presents data on the dispersed phase holdup of the ionic liquid [bmim][PF6] with water in a Karr extraction column. It was found that this system conforms to the standard slip velocity relationships and that the

Kelly K. L. Yung; Craig D. Smith; Tim A. Bowser; Jilska M. Perera; Geoffrey W. Stevens

2011-01-01

37

[Reparation and application of perfluorodecyl modified silica monolithic capillary column in extraction and enrichment of perfluorooctane sulfonates].  

PubMed

A perfluorodecyl modified silica monolithic capillary column has been prepared by using sol-gel method. The preparation steps included hydrolysis of alkoxy silane, fasculation of silanol, gelation, aging, meso-pore preparation, drying and surface modification. It could be used as a solid phase extraction (SPE) microcolumn for extraction and enrichment of perfluorooctane sulfonate (PFOS). The enrichment characteristics and efficiency of the perfluorodecyl modified monolithic silica capillary column has been investigated and compared with C18 silica monolithic capillary column. The results indicated that the perfluorodecyl modified silica monolithic capillary column ( 15 cm x 75 microm) had a higher adsorption capacity and a better enrichment selectivity for PFOS. The average adsorption capacity of the perfluorodecyl modified silica monolithic capillary column was 75 ng. And when the PFOS mass concentration in sample was 0. 25 mg/L, the enrichment factor was 29-fold in average. Owing to the good performance of the perfluorodecyl modified silica monolithic capillary column, it can be used for the extraction and enrichment of trace PFOS in water to meet the requirements of water quality monitoring and analysis. PMID:22268350

Huang, Ke; Zhou, Naiyuan; Chen, Bo

2011-10-01

38

Bonded-phase extraction column isolation of organic compounds in groundwater at a hazardous waste site  

USGS Publications Warehouse

A procedure for isolation of hazardous organic compounds from water for gas chromatography/mass spectrometry analysis Is presented and applied to creosote- and pentachlorophenol-contaminated groundwater resulting from wood-treatment processes. This simple procedure involved passing a 50-100-mL sample through a bonded-phase extraction column, eluting the trapped organic compounds from the column with 2-4 mL of solvent, and evaporating the sample to 100 ??L with a stream of dry nitrogen, after which the sample was ready for gas chromatography/mass spectrometry analysis. Representative compounds indicative of creosote contamination were used for recovery and precision studies from the cyclohexyl-bonded phase. Recovery of these compounds from n-octyl-, n-octadecyl-, cyclohexyl-, and phenyl-bonded phases was compared. The bonded phase that exhibited the best recovery and least bias toward acidic or basic cmpounds was the n-octadecyl phase. Detailed compound Identification Is given for compounds Isolated from creosote- and pentachlorophenol-contaminated groundwater using the cyclohexyl-bonded phase.

Rostad, C.E.; Pereira, W.E.; Ratcliff, S.M.

1984-01-01

39

Depth and rate of secondary carbonate accumulation in loess - 14C pulse labeling column experiment  

NASA Astrophysics Data System (ADS)

Pedogenic (secondary) carbonates are formed under arid and semiarid climatic conditions by reprecipitation of Ca2+ in soil solution with CO2 in soil air. In calcareous soil parent material, e.g. loess, this process leads to exchange of primary (lithogenic) carbon (C) with C from CO2, derived mainly from root respiration and microbial decomposition of plant remains. The resulting relation between ?13C values of soil CO2 and of secondary carbonate is used for reconstruction of paleovegetation and paleoenvironmental conditions. For such studies, the time frame of pedogenic carbonate formation is crucial, but still unknown. Several environmental factors, e.g. vegetation, temperature, moisture, affect rate and depth of secondary carbonate accumulation. Most soils of arid and semiarid regions contain a carbonate accumulation horizon (Bk, Ck, K), the depth of which is related to climatic conditions and properties of parent material. Based on C isotopic exchange during secondary carbonate formation, the aim of this study was to determine recrystallization rates and to localize the accumulation depth of secondary carbonate in an experiment with alternating moisture conditions. Acrylglas columns of 1 m height were filled with loess and planted with maize for six months. Contrary to soil, this loess contains solely primary CaCO3, has high CaCO3 content (29%) and nearly no organic carbon. Thus, we simulated initial soil formation on loess. Maize plants were pulse labeled in 14CO2 atmosphere at regular intervals of 3 weeks. Loess was wetted down to a maximum depth of 45 cm, and subsequent waterings were applied after the water level had decreased due to plant transpiration to less than 40% of WHC. After six months, plants were harvested and loess was cut into 5 cm slices. Amounts of secondary (recrystallized) CaCO3 were determined in each of the segments based on the 14C tracer assimilated by plants, then respired into rhizosphere and subsequently incorporated into newly formed secondary carbonate. After six months, 80% of recrystallized carbonate were leached from the uppermost 15 cm of the loess column, and 75% of total secondary carbonate were accumulated in a depth between 15 and 35 cm. The experiment confirmed the hypotheses that water movement in loess leads to a clear accumulation zone of recrystallized carbonate (although total CaCO3 content in loess was not changed after six months), the depth of carbonate accumulation is not related to depth of root penetration, the carbonate accumulation horizon correspond to the depth of wetting and drying. Based on calculated recrystallization rates (in the range of 10-5 day-1), leaching and accumulation of secondary carbonate, 1400 years are necessary for complete decalcification of the uppermost 15 cm of loess. Under the experimental conditions, this time interval represents the minimum age for formation of a calcic horizon.

Gocke, Martina; Pustovoytov, Konstantin; Kuzyakov, Yakov

2010-05-01

40

Determination of carbendazim in soil and lake water by immunoaffinity extraction and coupled-column liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

A method employing a high-performance protein G immunoaffinity column coupled to a reversed-phase analytical column through the use of a trapping column and INTEGRAL Micro-Analytical Workstation for the extraction of carbendazim from lake water samples and soil extracts is described. Characterization of the target analyte is achieved by on-line mass spectrometric analysis. The specificity of immunoaffinity extraction makes it possible

Karen A. Bean; Jack D. Henion

1997-01-01

41

Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption in the ASCENDS 2011 Airborne Campaign  

NASA Astrophysics Data System (ADS)

We have previously demonstrated an efficient pulsed, wavelength-resolved IPDA lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission. Our team participated in the 2010 ASCENDS airborne campaigns we flew airborne version of the CO2 and O2 lidar on the NASA DC-8. The CO2 lidar measures the atmospheric backscatter profiles and shape of the 1572.33 nm absorption line using 250 mW average laser power, 30 wavelength samples per scan and 300 scans per second. Most flights had 5-6 altitude steps to > 12 km, and clear CO2 line shapes were observed at all altitudes. Our post-flight analysis estimated the lidar range and pulse energies at each wavelength every second. We then solved for the best-fit CO2 absorption line shape, and calculated the Differential Optical Depth (DOD) at the line peak. We compared these to CO2 DODs calculated from spectroscopy based on HITRAN 2008 and the conditions from airborne in-situ readings. Analysis of the 2010 measurements over the Pacific Ocean and Lamont OK shows the expected ~linear change of the peak DOD with altitude. For measurements at altitudes > 6 km the random errors were ~ 0.3 ppm for 80 sec averaging times. After the 2010 flights we improved the airborne lidar's scan uniformity, calibration and receiver sensitivity. Our team participated in the seven ASCENDS science flights during late July and August 2011. These flights were made over a wide variety of surface and cloud conditions near the US, including over the central valley of California, over several mountain ranges, over both broken and solid stratus cloud deck over the Pacific Ocean, snow patches on mountain tops, over thin and broken clouds above the US Southwest and Iowa, and over forests near the WLEF tower in Wisconsin. Analyses show the retrievals of lidar range and CO2 column absorption, as well as estimates of CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds and to stratus cloud tops. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption profile (averaged for 50 sec) matched the predicted profile to better than 1% RMS error for all flight altitudes. For 1 & 10 second averaging, the scatter in the retrievals was limited by signal shot noise (i.e. the signal photon count). Analysis to date shows the decrease in CO2 due to vegetation when flying easterward over the Great Plains as well as the increase in CO2 concentration in the vicinity of the coal-fired power plant in New Mexico. Examples of these and other results will be presented.

Abshire, J. B.; Riris, H.; Allan, G. R.; Ramanathan, A.; Hasselbrack, W.; Mao, J.; Weaver, C. J.; Browell, E. V.

2012-12-01

42

Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption in the ASCENDS 2011 Airborne Campaign  

NASA Technical Reports Server (NTRS)

We have previously demonstrated an efficient pulsed, wavelength-resolved IPDA lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission. Our team participated in the 2010 ASCENDS airborne campaigns we flew airborne version of the CO2 and O2 lidar on the NASA DC-8. The CO2 lidar measures the atmospheric backscatter profiles and shape of the 1572.33 nm absorption line using 250 mW average laser power, 30 wavelength samples per scan and 300 scans per second. Most flights had 5-6 altitude steps to greater than 12 km, and clear CO2 line shapes were observed at all altitudes. Our post-flight analysis estimated the Iidar range and pulse energies at each wavelength every second. We then solved for the best-fit CO2 absorption line shape, and calculated the Differential Optical Depth (DOD) at the line peak. We compared these to CO2 DODs calculated from spectroscopy based on HITRAN 2008 and the conditions from airborne in-situ readings. Analysis of the 2010 measurements over the Pacific Ocean and Lamont OK shows the expected -linear change of the peak DOD with altitude. For measurements at altitudes greater than 6 km the random errors were approximately 0.3 ppm for 80 sec averaging times. After the 2010 flights we improved the airborne lidar's scan uniformity, calibration and receiver sensitivity. Our team participated in the seven ASCENDS science flights during late July and August 2011. These flights were made over a wide variety of surface and cloud conditions near the US, including over the central valley of California, over several mountain ranges, over both broken and solid stratus cloud deck over the Pacific Ocean, snow patches on mountain tops, over thin and broken clouds above the US Southwest and Iowa, and over forests near the WLEF tower in Wisconsin. Analyses show the retrievals of lidar range and CO2 column absorption, as wen as estimates of CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds and to stratus cloud tops. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption profile (averaged for 50 sec) matched the predicted profile to better than 1% RMS error for all flight altitudes. For 1 & 10 second averaging, the scatter in the retrievals was limited by signal shot noise (i.e. the sigual photon count). Analysis to date shows the decrease in CO2 due to vegetation when flying easterward over the Great Plains as well as the increase in CO2 concentration in the vicinity ofthe coal-fired power plant in New Mexico. Examples of these and other results will be presented.

Abshire, James B.; Riris, Haris; Allan, Graham R.; Ramanathan, Anand; Hasselbrack, William E.; Mao, Jianping; Weaver, Clark; Browell, Edward V.

2012-01-01

43

Determination of phenylenediamine isomers in hair dyes by coal cinders micro-column extraction and MEKC.  

PubMed

A new micellar electrokinetic chromatography (MEKC) method using beta-cyclodextrins (?-CDs) and 1-butyl-3-methylimidazolium hexafluorophosphates (ionic liquids) as additives was successfully developed for determination of para-, meta-, and ortho-phenylenediamines isomers (p-P, m-P, and o-P) in hair dyes. To improve the sensitivity of the MEKC-UV, a simple and cheap flow injection (FI) technique using a micro-column packed with coal cinders (the by-products from combustion in a boiler) as solid-phase extractant was also investigated. In the presence of 20 mmol L(-1) phosphates at pH 5.5, addition of 12 mmol L(-1) ionic liquids and 8 mmol L(-1) ?-CDs greatly improved the separation efficiency. The three analytes could be quantitatively adsorbed by coal cinders, and desorbed readily with 0.15 mL of 0.01 mol L(-1) NaOH. Under the optimum conditions, an enrichment factor (EF) of 33.3 was obtained, and determination limits of p-P, m-P, and o-P were 1.97?×?10(-7), 0.99?×?10(-7), and 0.61?×?10(-7) mol L(-1), respectively. The adsorption capacities of the coal cinders micro-column for p-P, m-P, and o-P were all 1.20 mg g(-1). The presented procedure was successfully applied to the determination of p-P, m-P, and o-P in hair dyes with satisfactory results. PMID:21475944

Wu, Yiwei; Jiang, Feng; Chen, Lin; Zheng, Jing; Deng, Zhenli; Tao, Qing; Zhang, Jing; Han, Lijuan; Wei, Xiaoshu; Yu, Aimin; Zhang, Haili

2011-06-01

44

Efficient Melt Stirring Using Pulse Sequences of a Rotating Magnetic Field: Part I. Flow Field in a Liquid Metal Column  

NASA Astrophysics Data System (ADS)

The use of a pulsed, rotating magnetic field (RMF) is presented as an auspicious method for obtaining an intensive stirring and mixing in a pool of liquid metal; the RMF pulses within a sequence have been applied with a constant or alternating direction. The resulting flow structure in a cylindrical liquid metal column has been explored by numerical simulations and by model experiments, using the ternary alloy GaInSn. Ultrasonic Doppler velocimetry (UDV) has been used to determine profiles of the vertical velocity. Both the numerical results and the velocity measurements demonstrate the capability of the proposed stirring regimes for overcoming the limited mixing character of conventional rotary stirring. The application of a time-modulated RMF offers considerable potential for providing an optimal flow pattern in a solidifying melt, for reasons of a well-aimed modification of casting properties.

Eckert, S.; Nikrityuk, P. A.; Räbiger, D.; Eckert, K.; Gerbeth, G.

2007-12-01

45

Effect of pressure pulses at the interface valve on the stability of second dimension columns in online comprehensive two-dimensional liquid chromatography.  

PubMed

Users of online comprehensive two-dimensional liquid chromatography (LCxLC) frequently acknowledge that the mechanical instability of HPLC columns installed in these systems, particularly in the second dimension, is a significant impediment to its use. Such instability is not surprising given the strenuous operating environment to which these columns are subjected, including the large number (thousands per day) of fast and large pressure pulses resulting from interface valve switches (on the timescale of tens of milliseconds) associated with very fast second dimension separations. There appear to be no published reports of systematic studies of the relationship between second dimension column lifetime and any of these variables. In this study we focused on the relationship between the lifetimes of commercially available columns and the pressure pulses observed at the inlet of the second dimension column that occur during the switching of the valve that interfaces the two dimensions of a LCxLC system. We find that the magnitude of the pressure drop at the inlet of the second dimension column during the valve switch, which may vary between 10 and 95% of the column inlet pressure, is dependent on valve switching speed and design, and has a dramatic impact on column lifetime. In the worst case, columns fail within the first few hours of use in an LCxLC system. In the best case, using a valve that exhibits much smaller pressure pulses, the same columns exhibit much improved lifetimes and have been used continuously under LCxLC conditions for several days with no degradation in performance. This result represents a first step in understanding the factors that affect second dimension column lifetime, and will significantly improve the usability of the LCxLC technique in general. PMID:25553909

Talus, Eric S; Witt, Klaus E; Stoll, Dwight R

2015-01-23

46

Analysis of Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption from 3-13 km Altitudes  

NASA Technical Reports Server (NTRS)

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS space mission [1]. It uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1575 nm band, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver measures the energies of the laser echoes from the surface along with the range profile of scattering in the path. The column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off-line signals via the integrated path differential absorption (IPDA) technique. The time of flight of the laser pulses is used to estimate the height of the scattering surface and to reject laser photons scattered in the atmosphere. We developed an airborne lidar to demonstrate an early version of the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar stepped the pulsed laser's wavelength across the selected CO2 line with 20 wavelength steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a NIR photomultiplier and is recorded on every other reading by a photon counting system [2]. During August 2009 we made a series of 2.5 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over locations in the US, including the SGP ARM site in Oklahoma, central Illinois, north-eastern North Carolina, and over the Chesapeake Bay and the eastern shore of Virginia. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, and in-situ measurements were made using its CO2 sensor and radiosondes. We have conducted an analysis of the ranging and IPDA lidar measurements from these four flights. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We used a cross-correlation approach to process the laser echo records. This was used to estimate the range to the scattering surface, to define the edges of the laser pulses and to determine echo pulse energy at each wavelength. We used a minimum mean square approach to fit an instrument response function and to solve for the best-fit CO2 absorption line shape. We then calculated the differential optical depth (DOD) of the fitted CO2 line. We computed its statistics at the various altitude steps, and compare them to the DODs calculated from spectroscopy based on HITRAN 2008 and the column conditions calculated from the airborne in-situ readings. The results show the lidar and in-situ measurements have very similar DOD change with altitude and greater than 10 segments per flight where the scatter in the lidar measurements are less than or equal to 1ppm. We also present the results from subsequent CO2 column absorption measurements, which were made with stronger detected signals during three flights on the NASA DC-8 over the southwestern US in during July 2010.

Abshire, James B.; Weaver, Clark J.; Riris, Haris; Mao, Jianping; Sun, Xiaoli; Allan, Graham R.; Hasselbrack, William; Browell, Edward V.

2011-01-01

47

Method for making a non-extractable stationary phase of polymer within a capillary column  

DOEpatents

A method is described for coating interior capillary column surfaces, or packing material of a packed column, used for gas chromatography, with a stationary polymer phase that is cross-linked by exposing it to a low-temperature plasma that is uniformly distributed over the column or packing material for a predetermined period of time to effect the desired degree of cross-linking of the coating. 7 figs.

Springston, S.R.

1990-10-30

48

Method for making a non-extractable stationary phase of polymer within a capillary column  

DOEpatents

A method for coating interior capillary column surfaces, or packing material of a packed column, used for gas chromatography, with a stationary polymer phase that is cross-linked by exposing it to a low-temperature plasma that is uniformly distributed over the column or packing material for a predetermined period of time to effect the desired degree of cross-linking of the coating.

Springston, Stephen R. (Middle Island, NY)

1990-01-01

49

Determination of aflatoxin B1 in sidestream cigarette smoke by immunoaffinity column extraction coupled with liquid chromatography/mass spectrometry.  

PubMed

Aflatoxins produced by food-borne molds are known carcinogenic toxins. Aflatoxin B1 (AFB1) is reported as the most toxic of this class of mycotoxins. We have coupled immunoaffinity column extraction with LC/MS to produce a sensitive and selective approach for the study of AFB1. As AFB1 can be potentially found in tobacco it is of interest to establish whether AFB1 can be transferred from a cigarette fortified with AFB1, to the sidestream smoke. Previous studies have found that AFB1 does not transfer to the mainstream smoke. Since sidestream smoke may contain higher concentrations of some smoke components, a method was developed to analyze the sidestream smoke produced from machine-smoked cigarettes. Sidestream smoke condensates collected on Cambridge filter pads were extracted with isopropanol, then further purified using immunoaffinity extraction columns. The extracts were then analyzed by LC/MS and LC/MS/MS. An instrumental limit of detection (LOD) was established at 3.75 pg injected on column, with the limit of quantitation (LOQ) equal to 11.25 pg on column for both LC/MS and LC/MS/MS. The instrument was found to be linear from 11.25 pg to 150 pg (r > 0.995.) Precision ranged from 4.2% to 8.4% at the LOQ, while accuracy ranged from 0.53% to 1.33%. The immunoaffinity extraction method LOD was determined to be 100 pg fortified onto the Cambridge filter. The LOQ was 350 pg. The average recovery of the AFB1 from the Cambridge pad was 82.9% over the range of 100-1000 pg fortified onto the pad. AFB1 was not detected in unfortified cigarettes. A transfer experiment, fortifying cigarettes at 1 microg/cigarette determined that AFB1 was transferred only slightly from the burning cigarette to the sidestream smoke. The mean percent transfer was 0.087%. PMID:16078698

Edinboro, Leslie E; Karnes, H Thomas

2005-08-12

50

Self-Organized Micro-Columns and Nano-Spheres Generated by Pulsed Laser Ablation of Ti/Al Alloy in Water  

NASA Astrophysics Data System (ADS)

Dense arrays of micro-columns are formed on the surface of Ti-Al alloy by cumulative nanosecond pulsed laser ablation in water. The fabric-like structure characterized by Ti-Al nano-spheres absorbed on micro-cluster in liquid is most likely responsible for the occurrence of laser micro-etching and localized melting, resulting in continuous deepening of micro-holes and the formation of micro-columns. Laser induced plasma spectroscopy is carried out to reveal the effect of micro-columns on subsequent pulse laser ablation. The intensity of spectral lines from Ti ions by additional laser ablation of the modified spot is higher than that created over a smooth surface. These results suggest that the micro-columns lead to an enhanced absorption of the following laser energy. The proposed results and relevant discussions are of importance for the development of light-trapping coatings on a metal surface.

Cui, Qing-Qiang; Liu, Xiang-Dong; Chen, Ming; Zhao, Ming-Wen; Wang, Chun-Sheng; Li, Shuang

2014-01-01

51

Forest fire smog feature extraction based on Pulse-Coupled neural network  

Microsoft Academic Search

A novel algorithm for image-based forest fire smog feature extraction based on Pulse-Coupled neural network (PCNN) is proposed. The PCNN is derived from the phenomena of synchronous pulse burst in mammals' visual cortex. The outputs of PCNN represent unique features of imported images, and has been proved to be invariant to translation, rotation and distortion. In this paper the image

Wu Jiang; Huang Rule; Xu Ziyue; Han Ning

2011-01-01

52

Water pulse migration through semi-infinite vertical unsaturated porous column with special relative-permeability functions: Exact solutions  

NASA Astrophysics Data System (ADS)

The paper presents certain exact solutions describing the vertical movement of a water pulse through a semi-infinite unsaturated porous column. The saturation-based form of the Richards' equation is used with special power law relative-permeability functions. Both capillary and gravity effects are taken into account. Three exact solutions are derived corresponding to three relative-permeability functions, linear, quadratic and cubic. The Richards' equation is nonlinear for the three cases. The solutions are obtained by applying a general similarity transformation. They are explicit in space and time variables and do not contain any approximation. They describe the evolution of the water saturation in the vertical column and they can be used to predict the post-infiltration movement of a finite quantity of water. Exact expressions of the masses of water leaving a given depth are also derived for the three cases. We analyze the effect of relative-permeability and capillary pressure. The proposed solutions are also useful for checking numerical schemes. One of the exact solutions is used to validate numerical solution obtained from an arbitrary initial condition. Results show that the numerical solution converges to the exact solution for large times.

Hayek, Mohamed

2014-09-01

53

Binary solvent extraction system and extraction time effects on phenolic antioxidants from kenaf seeds (Hibiscus cannabinus L.) extracted by a pulsed ultrasonic-assisted extraction.  

PubMed

The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, ? -carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP) assay. Total phenolic content (TPC) and total flavonoid content (TFC) evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance liquid chromatography (HPLC) to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15?min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20?mg/100?g extract) and sinapic acid (1198.22?mg/100?g extract), which can be used as alternative antioxidants in the food industry. PMID:24592184

Wong, Yu Hua; Lau, Hwee Wen; Tan, Chin Ping; Long, Kamariah; Nyam, Kar Lin

2014-01-01

54

Fluidized-bed column method for automatic dynamic extraction and determination of trace element bioaccessibility in highly heterogeneous solid wastes.  

PubMed

Dynamic flow-through extraction/fractionation methods have recently drawn much attention as appealing alternatives to the batchwise steady-state counterparts for the evaluation of environmentally available pools of potentially hazardous trace elements in solid matrices. The most critical weakness of flow-based column approaches lies in the small amount of solid that can be handled, whereby their applicability has been merely limited to date to the extraction of trace elements in highly homogeneous solid substrates; otherwise the representativeness of the test portion might not be assured. To tackle this limitation, we have devised an automated flow-through system incorporating a specially designed extraction column with a large volume capacity, wherein up to 2 g of solid sample could be handled without undue backpressure. The assembled flow setup was exploited for fast screening of potentially hazardous trace elements (namely, Cd, Cr, Cu, Pb, and Zn) in highly inhomogeneous municipal solid waste incineration (MSWI) bottom ashes. The pools of readily mobilizable metal forms were ascertained using the Toxicity Characteristic Leaching Procedure (TCLP) based on the usage of 0.1 mol L(-1) CH(3)COOH as leachant and analysis of extracts by inductively coupled optical emission spectrometry. The application of a two-level full factorial (screening) design revealed that the effect of sample fluidization primarily but other experimental factors such as the solid to liquid ratio and extractant flow rate significantly influenced the leachability of given elements in raw bottom ashes at the 0.05 significance level. The analytical performance of the novel flow-based method capitalized on fluidized-bed extraction was evaluated in terms of accuracy, through the use of mass balance validation, reproducibility and operational time as compared to batchwise extraction and earlier flow injection/sequential injection microcolum-based leaching tests. PMID:20082772

Rosende, María; Miró, Manuel; Cerdŕ, Víctor

2010-01-18

55

Pulse Profiles, Accretion Column Dips and a Flare in GX 1+4 During a Faint State  

NASA Technical Reports Server (NTRS)

The Rossi X-ray Timing Explorer (RXTE) spacecraft observed the X-ray GX 1+4 for it period of 34 hours on July 19/20 1996. The source faded front an intensity of approximately 20 mcrab to a minimum of <= 0.7 mcrab and then partially recovered towards the end of the observation. This extended minimum lasted approximately 40,000 seconds. Phase folded light curves at a barycentric rotation period of 124.36568 +/- 0.00020 seconds show that near the center of the extended minimum the source stopped pulsing in the traditional sense but retained a weak dip feature at the rotation period. Away from the extended minimum the dips are progressively narrower at higher energies and may be interpreted as obscurations or eclipses of the hot spot by the accretion column. The pulse profile changed from leading-edge bright before the extended minimum to trailing-edge bright after it. Data from the Burst and Transient Source Experiment (BATSE) show that a torque reversal occurred < 10 days after our observation. Our data indicate that the observed rotation departs from a constant period with a P/P value of approximately -1.5% per year at a 4.5sigma significance. We infer that we may have serendipitously obtained data, with high sensitivity and temporal resolution about the time of an accretion disk spin reversal. We also observed a rapid flare which had some precursor activity close to the center of the extended minimum.

Giles, A. B.; Galloway, D. K.; Greenhill, J. G.; Storey, M. C.; Wilson, C. A.

1999-01-01

56

In-process inventory estimation for pulsed columns and mixer-settlers  

SciTech Connect

Nuclear materials accounting and control in fuels reprocessing plants can be improved by near-real-time estimation of the nuclear materials inventory in solvent-extraction contactors. Techniques are being developed for the estimation of the in-process inventory in contactors. These techniques are derived from recent developments in chemical modeling of contactor systems, on-line measurements for materials accounting and control of the Purex process, and computer-based data acquisition and analysis methods.

Cobb, D.D.; Burkhart, L.E.; Beyerlein, A.L.

1980-01-01

57

Determination of myo-inositol (free and bound as phosphatidylinositol) in infant formula and adult nutritionals by liquid chromatography/pulsed amperometry with column switching: first action 2011.18.  

PubMed

Myo-inositol is a 6-carbon cyclic polyalcohol also known as meso-inositol, meat sugar, inosite, and i-inositol. It occurs in nature in both free (myo-inositol) and bound (inositol phosphates and phosphatidylinositol) forms. For the determination of free myo-inositol, samples are mixed with dilute hydrochloric acid to extract myo-inositol and precipitate proteins, diluted with water, and filtered. For the determination of myo-inositol bound as phosphatidylinositol, samples are extracted with chloroform, isolated from other fats with silica SPE cartridges, and hydrolyzed with concentrated acid to free myo-inositol. Prepared samples are first injected onto a Dionex CarboPac PA1 column, which separates myo-inositol from other late-eluting carbohydrates. After column switching, myo-inositol is further separated on a CarboPac MA1 column using a 0.12% sodium hydroxide mobile phase; strongly retained carbohydrates are eluted from the PA1 column with a 3% sodium hydroxide mobile phase. Eluant from the CarboPac MA1 analytical column passes through an electrochemical detector cell where myo-inositol is detected by pulsed amperometry using a gold electrode. The method showed appropriate performance characteristics versus selected established standard method performance requirement parameters for the determination of myo-inositol: linear response; repeatability (RSDr) of 2%; and intermediate precision (RSDir) of 2.5%. Instrument LOD and LOQ were 0.0004 and 0.0013 mg/100 mL, respectively, and correspond to a free myo-inositol quantitation limit of 0.026 mg/100 g and a phosphatidylinositol quantitation limit of 0.016 mg/100 g. Correlation with the reference microbiological assay was good. The proposed method has been accepted by the Expert Review Panel as an AOAC First Action Method, suitable for the routine determination of myo-inositol in infant formula and adult nutritionals. PMID:22970560

Schimpf, Karen; Thompson, Linda; Baugh, Steve

2012-01-01

58

Analysis of Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption During the ASCENDS 2009-2011 Airborne Campaigns  

NASA Technical Reports Server (NTRS)

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs altitude. The measurements showed 1 ppm random errors for 8-10 km altitudes and 30 sec averaging times. For the 2010 ASCENDS campaigns we flew the CO2lidar on the NASA DC-8 and added an 02lidar channel. During July 2010 we made measurements of CO2 and O2 column absorption during longer flights over Railroad Valley NV, the Pacific Ocean and over Lamont OK. CO2 measurements were made with 30 steps/scan, 300 scans/sec and improved line resolution and receiver sensitivity. Analysis of the 2010 CO2 measurements shows the expected linear change of DOD with altitude. For measurements at altitudes> 6 km the random errors were 0.3 ppm for 80 sec averaging times. For the summer 2011 ASCENDS campaigns we made further improvements to the lidar's CO2 line scan and receiver sensitivity. We demonstrated measurements over the California Central Valley, to stratus cloud tops over the Pacific Ocean, over mountain regions with snow, and over several areas with broken clouds. Details of the lidar measurements and their analysis will be described in the presentation.

Abshire, J. B.; Weaver, C. J.; Riris, H.; Mao, J.; Sun, X; Allan, G. R.; Hasselbrack, W. E.; Browell, E. V.

2012-01-01

59

Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption and Range During the ASCENDS 2009-2011 Airborne Campaigns  

NASA Technical Reports Server (NTRS)

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar only on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear C02 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed in detail and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs altitude. The measurements showed -1 ppm random errors for 8-10 km altitudes and -30 sec averaging times. For the 2010 ASCENDS campaigns we flew the CO2 lidar on the NASA DC-8 and added an O2 lidar channel. During July 2010 we made measurements of CO2 and O2 column absorption during longer flights over Railroad Valley NV, the Pacific Ocean and over Lamont OK. CO2 measurements were made with 30 steps/scan, 300 scans/sec and improved line resolution and receiver sensitivity. Analysis of the 2010 CO2 measurements shows the expected -linear change of DOD with altitude. For measurements at altitudes> 6 km the random errors were 0.3 ppm for 80 sec averaging times. For the summer 2011 ASCENDS campaigns we made further improvements to the lidar's CO2 line scan and receiver sensitivity. The seven flights in the 2011 Ascends campaign were flown over a wide variety of surface and cloud conditions in the US, which produced a wide variety of lidar signal conditions. Details of the lidar measurements and their analysis will be described in the presentation.

Abshire, J. B.; Weaver, C. J.; Riris, H.; Mao, J.; Sun, X.; Allan, G. R.; Hasselbrack, W. E.; Browell, E. V.

2012-01-01

60

Extracting concrete thermal characteristics from temperature time history of RC column exposed to standard fire.  

PubMed

A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in the column section. A thermal equilibrium model in unsteady-state condition was developed. The thermal conductivity of concrete was then determined by optimizing the numerical solution of the model to meet the observed time history of temperature variations. The determined thermal conductivity with respect to temperature was then verified against standard thermal conductivity measurements of concrete bricks. It is concluded that the proposed method can be used to conservatively estimate thermal conductivity of concrete for design purpose. Finally, the thermal radiation properties of concrete for the RC column were estimated from the thermal equilibrium at the surface of the column. The radiant heat transfer ratio of concrete representing absorptivity to emissivity ratio of concrete during fire was evaluated and is suggested as a concrete criterion that can be used in fire safety assessment. PMID:25180197

Kim, Jung J; Youm, Kwang-Soo; Reda Taha, Mahmoud M

2014-01-01

61

Extracting Concrete Thermal Characteristics from Temperature Time History of RC Column Exposed to Standard Fire  

PubMed Central

A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in the column section. A thermal equilibrium model in unsteady-state condition was developed. The thermal conductivity of concrete was then determined by optimizing the numerical solution of the model to meet the observed time history of temperature variations. The determined thermal conductivity with respect to temperature was then verified against standard thermal conductivity measurements of concrete bricks. It is concluded that the proposed method can be used to conservatively estimate thermal conductivity of concrete for design purpose. Finally, the thermal radiation properties of concrete for the RC column were estimated from the thermal equilibrium at the surface of the column. The radiant heat transfer ratio of concrete representing absorptivity to emissivity ratio of concrete during fire was evaluated and is suggested as a concrete criterion that can be used in fire safety assessment. PMID:25180197

2014-01-01

62

Extraction of quadrature phase information from multiple pulse NMR signals  

NASA Technical Reports Server (NTRS)

A multiple pulse sequence (8-pulse sequence) used for high-resolution solid state NMR is analyzed with regard to the information available from each of the four wide sampling windows. It is demonstrated that full quadrature phase information can be obtained using only a single phase detector and that, for the commonly encountered situation where the spectral width is much less than the folding frequency, the signals from the various windows can be combined easily using standard complex Fourier transform software. An improvement in the signal-to-noise ratio equal to the square root of 3 is obtained over either standard single or quadrature phase detection schemes. Procedures for correcting spectral distortions are presented.

Rhim, W.-K.; Burum, D. P.; Vaughan, R. W.

1976-01-01

63

Improved protocol for the simultaneous extraction and column-based separation of DNA and RNA from different soils.  

PubMed

We developed an improved protocol, allowing the simultaneous extraction of DNA and RNA from soil using phenol-chloroform with subsequent column-based separation of DNA and RNA (PCS). We compared this new approach with the well established protocol published by Griffiths et al. (2000), where DNA and RNA are separated by selective enzymatic digestions and two commercial kits used for DNA or RNA extraction, respectively, using four different agricultural soils. We compared yield and purity of the nucleic acids as well as abundance and diversity profiles of the soil bacterial communities targeting the nosZ gene via quantitative real-time PCR and terminal restriction fragment length polymorphism on DNA and RNA level. The newly developed protocol provided purer nucleic acid extracts compared to the used kit-based protocols. All protocols were suitable for DNA- and RNA-based gene quantification, however high variations between replicates were obtained for RNA samples using the original Griffiths protocol. Diversity patterns of nosZ were highly influenced by the extraction protocol used both on the DNA and RNA level. Finally, our data showed that the new protocol allows a simultaneous and reproducible extraction and separation of DNA and RNA, which were suitable for reliable analyses of gene and transcript copy numbers and diversity pattern. PMID:21256887

Töwe, Stefanie; Wallisch, Stefanie; Bannert, Andrea; Fischer, Doreen; Hai, Brigitte; Haesler, Felix; Kleineidam, Kristina; Schloter, Michael

2011-03-01

64

Online micro-solid-phase extraction based on boronate affinity monolithic column coupled with high-performance liquid chromatography for the determination of monoamine neurotransmitters in human urine.  

PubMed

Quantification of monoamine neurotransmitters is very important in diagnosing and monitoring of patients with neurological disorders. We developed an online analytical method to selectively determine urinary monoamine neurotransmitters, which coupled the boronate affinity monolithic column micro-solid-phase extraction with high-performance liquid chromatography (HPLC). The boronate affinity monolithic column was prepared by in situ polymerization of vinylphenylboronic acid (VPBA) and N,N'-methylenebisacrylamide (MBAA) in a stainless capillary column. The prepared monolithic column showed good permeability, high extraction selectivity and capacity. The column-to-column reproducibility was satisfactory and the enrichment factors were 17-243 for four monoamine neurotransmitters. Parameters that influence the online extraction efficiency, including pH of sample solution, flow rate of extraction and desorption, extraction volume and desorption volume were investigated. Under the optimized conditions, the developed method exhibited low limit of detection (0.06-0.80?g/L), good linearity (with R(2) between 0.9979 and 0.9993). The recoveries in urine samples were 81.0-105.5% for four monoamine neurotransmitters with intra- and inter-day RSDs of 2.1-8.2% and 3.7-10.6%, respectively. The online analytical method was sensitive, accurate, selective, reliable and applicable to analysis of trace monoamine neurotransmitters in human urine sample. PMID:24703360

Yang, Xiaoting; Hu, Yufei; Li, Gongke

2014-05-16

65

Analysis of Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption in the ASCENDS 2011 and 2013 Airborne Campaigns  

NASA Astrophysics Data System (ADS)

We have developed a pulsed, wavelength-resolved IPDA lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission. The CO2 lidar flies on NASA's DC-8 aircraft and measures the atmospheric backscatter profiles and shape of the 1572.33 nm absorption line using 250 mW average laser power, 30 wavelength samples per scan with 300 scans per second. Our post-flight analysis estimates the lidar range and pulse energies at each wavelength every second. We then solve for the optimum CO2 absorption line shape, and calculated the Differential Optical Depth (DOD) at the line peak and the column average CO2 concentrations. We compared these to radiative transfer calculations based on the HITRAN 2008 database, the atmospheric conditions, and the CO2 concentrations sampled by in-situ sensors on the aircraft. Our team participated in the ASCENDS science flights during July and August 2011. These flights were made over a wide variety of surface and cloud conditions near the US, including over the central valley of California, over several mountain ranges, over both broken and solid stratus cloud deck over the Pacific Ocean, over thin and broken clouds above the US Southwest and Iowa, and over forests near the WLEF tower in Wisconsin. Most flights had 5-6 altitude steps to > 12 km, and clear CO2 absorption line shapes were recorded. Analyses show the retrievals of lidar range and CO2 column absorption, as well as estimates of CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds and to stratus cloud tops. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption profile (averaged for 50 sec) matched the predicted profile to better than 1% RMS error for all flight altitudes. For 10 second averaging, the scatter in the retrievals was typically 2-3 ppm and was limited by signal shot noise (i.e. the signal photon count). For flight altitudes above 5 km the biases in retrieved concentrations were 1-2 ppm. Analysis shows the decrease in CO2 due to vegetation when flying over Iowa cropland as well as the sudden increases in CO2 concentration near a coal-fired power plant in New Mexico. Our team also participated in the February 2013 ASCENDS flight campaign, flying over a variety of surfaces in the US, including over Railroad Valley NV, the California Central Valley, desert areas in Arizona, and over cold snow fields in the Rocky Mountains of Colorado and warmer snow in Iowa and Wisconsin. Our post-flight analyses showed that the retrievals of lidar range, lineshape and CO2 column absorption and concentrations worked well when measuring over topography with rapidly changing height and reflectivity, and through thin clouds. As expected, the relative reflectivity of snow surfaces near 1572 nm was small, about 10% of that of the desert, and good line fits and retrievals were made to these as well. Examples from analyzing the 2011 and 2013 measurements will be presented.

Abshire, J. B.; Ramanathan, A.; Mao, J.; Riris, H.; Allan, G. R.; Hasselbrack, W.; Weaver, C. J.; Browell, E. V.

2013-12-01

66

Enhanced anthocyanin extraction from red cabbage using pulsed electric field processing.  

PubMed

This study was conducted to evaluate the effect of pulsed electric field (PEF) treatment on anthocyanin extraction from red cabbage using water as a solvent. Mashed cabbage was placed in a batch treatment chamber and subjected to PEF (2.5 kV/cm electric field strength; 15 micros pulse width and 50 pulses, specific energy 15.63 J/g). Extracted anthocyanin concentrations (16 to 889 microg/mL) were determined using HPLC. Heat and light stabilities of the control and PEF-treated samples, having approximately the same initial concentrations, were studied. PEF treatments enhanced total anthocyanin extraction in water from red cabbage by 2.15 times with a higher proportion of nonacylated forms than the control (P < 0.05). The heat and light stabilities of the PEF-treated samples and control samples were not significantly different (P > 0.05). Practical Application: An innovative pretreatment technology, pulsed electric field processing, enhanced total anthocyanin extraction in water from red cabbage by 2.15 times. Manufacturers of natural colors can use this technology to extract anthocyanins from red cabbage efficiently. PMID:20722916

Gachovska, Tanya; Cassada, David; Subbiah, Jeyamkondan; Hanna, Milford; Thippareddi, Harshavardhan; Snow, Daniel

2010-08-01

67

Simple and highly effective DNA extraction methods from old skeletal remains using silica columns  

Microsoft Academic Search

The recovery of DNA data from old skeletal remains is often difficult due to degraded and very low yield of extracted DNA and the presence of PCR inhibitors. Herein, we compared several silica-based DNA extraction methods from artificially degraded DNA, DNA with PCR inhibitors and DNA from old skeletal remains using quantitative real-time PCR. We present a modified large-scale silica-based

Hwan Young Lee; Myung Jin Park; Na Young Kim; Jeong Eun Sim; Woo Ick Yang; Kyoung-Jin Shin

2010-01-01

68

[Determination of free formaldehyde in cosmetics by pre-column derivatization, extraction inhibition and high performance liquid chromatography].  

PubMed

Pre-column derivatization and inhibition by solvent extraction were applied to determine free formaldehyde in cosmetics by high performance liquid chromatography (HPLC). Due to the rapid decomposition of formaldehyde donors in the derivatization, it is hard to detect the amount of the free formaldehyde in cosmetics. The formaldehyde directly reacted with 2,4-dinitrophenylhydrazine in acetonitrile-phosphate buffer (pH 2) (1:1, v/v) solution for 2 min, then dichloromethane extraction was used to induce the decomposition of formaldehyde donors. The extract was diluted with acetonitrile and then determined by HPLC. The formaldehyde derivative was separated on an Agilent C18 column (250 mm x 4.6 mm, 5 microm) at 30 degrees C with acetonitrile-water (60:40, v/v) as mobile phase at a flow rate of 1.0 mL/min, and detected at the wavelength of 355 nm. The recoveries were from 81% to 106% at the spiked levels of 50, 100, 500, 1 000 microg/g of formaldehyde in shampoo, milk, cream, hand cleaner, toothpaste, nail polish, powder separately, and the relative standard deviations (n = 6) were less than 5.0%. The limit of quantification of the formaldehyde in cosmetics was 50 microg/g. The method has been applied to the determination of free formaldehyde in real samples and the results showed that the release by formaldehyde donors was inhibited. The method has the advantages of simple operation, good accuracy and meets the requirement of determination of free formaldehyde in cosmetics. PMID:23593888

Lü, Chunhua; Huang, Chaoqun; Chen, Mei; Xie, Wen; Chen, Xiaomei

2012-12-01

69

Extracting breathing rate information from a wearable reflectance pulse oximeter sensor  

Microsoft Academic Search

The integration of multiple vital physiological measurements could help combat medics and field commanders to better predict a soldier's health condition and enhance their ability to perform remote triage procedures. In this paper we demonstrate the feasibility of extracting accurate breathing rate information from a photoplethysmographic signal that was recorded by a reflectance pulse oximeter sensor mounted on the forehead

W. S. Johnston; Y. Mendelson

2004-01-01

70

A feature extraction technique based on principal component analysis for pulsed Eddy current NDT  

Microsoft Academic Search

Pulsed Eddy current (PEC) is a new emerging NDT technique for sub-surface defect detection. The technique mainly uses the response peak value and arrival to detect and quantify the defects. This could suffer from noise and be not sufficient to extract more information about the defects, e.g. depth information of defects. This paper introduces the application of principal component analysis

Ali Sophian; Gui Yun Tian; David Taylor; John Rudlin

2003-01-01

71

Direct extraction of coherent mode properties from imaging measurements in a linear plasma column  

SciTech Connect

Spectral properties of coherent waves in an argon plasma column are examined using fluctuation data from fast imaging. Visible light from ArII line emission is collected at high frame rates using a high-speed digital camera. A cross-spectral phase technique allows direct visualization of dominant phase structures as a function of frequency, as well as identification of azimuthal asymmetries present in the system. Experimental dispersion estimates are constructed from imaging data alone. Drift-like waves are identified by comparison with theoretical dispersion curves, and a tentative match of a low-frequency spectral feature to Kelvin-Helmholtz-driven waves is presented. Imaging measurements are consistent with previous results, and provide non-invasive, single-shot measurements across the entire plasma cross-section. Implications of the measured spectral properties for imaging measurements of mode dynamics are explored.

Light, A. D.; Sechrest, Y.; Munsat, T. [Center for Momentum Transport and Flow Organization, University of California San Diego, La Jolla, California 92093 (United States) [Center for Momentum Transport and Flow Organization, University of California San Diego, La Jolla, California 92093 (United States); Center for Integrated Plasma Studies, Department of Physics, University of Colorado Boulder, Boulder, Colorado 80309 (United States); Thakur, S. C.; Brandt, C.; Tynan, G. R. [Center for Momentum Transport and Flow Organization, University of California San Diego, La Jolla, California 92093 (United States) [Center for Momentum Transport and Flow Organization, University of California San Diego, La Jolla, California 92093 (United States); Department of Mechanical and Aerospace Engineering and Center for Energy Research, University of California San Diego, La Jolla, California 92093 (United States)

2013-08-15

72

Respiratory rate extraction from pulse oximeter and electrocardiographic recordings.  

PubMed

We present an algorithm of respiratory rate extraction using particle filter (PF), which is applicable to both photoplethysmogram (PPG) and electrocardiogram (ECG) signals. For the respiratory rate estimation, 1 min data are analyzed with combination of a PF method and an autoregressive model where among the resultant coefficients, the corresponding pole angle with the highest magnitude is searched since this reflects the closest approximation of the true breathing rate. The PPG data were collected from 15 subjects with the metronome breathing rate ranging from 24 to 36 breaths per minute in the supine and upright positions. The ECG data were collected from 11 subjects with spontaneous breathing ranging from 36 to 60 breaths per minute during treadmill exercises. Our method was able to accurately extract respiratory rates for both metronome and spontaneous breathing even during strenuous exercises. More importantly, despite slow increases in breathing rates concomitant with greater exercise vigor with time, our method was able to accurately track these progressive increases in respiratory rates. We quantified the accuracy of our method by using the mean, standard deviation and interquartile range of the error rates which all reflected high accuracy in estimating the true breathing rates. We are not aware of any other algorithms that are able to provide accurate respiratory rates directly from either ECG signals or PPG signals with spontaneous breathing during strenuous exercises. Our method is near real-time realizable because the computational time on 1 min data segment takes only 10 ms on a 2.66 GHz Intel Core2 microprocessor; the data are subsequently shifted every 10 s to obtain near-continuous breathing rates. This is an attractive feature since most other techniques require offline data analyses to estimate breathing rates. PMID:22027352

Lee, Jinseok; Florian, John P; Chon, Ki H

2011-11-01

73

Column SolidPhase Extraction with 2-Acetylmercaptophenyldiazoaminoazobenzene (AMPDAA) Impregnated Amberlite XAD-4 and Determination of Trace Heavy Metals in Natural Waters by Flame Atomic Absorption Spectrometry  

Microsoft Academic Search

A column solid-phase extraction (SPE) preconcentration method was developed for the determination of Cd, Co, Cu, Ni and Zn ions in natural water samples by flame atomic absorption spectrometry. The procedure is based on the retention of analytes in the form of 2-acetylmercaptophenyldiazoaminoazobenzene (AMPDAA) complexes on a short column of AMPDAA-XAD-4 resin from buffered sample solution and subsequent elution with

Yongwen Liu; Yong Guo; Xijun Chang; Shuangming Meng; Dong Yang; Bingjun Din

2005-01-01

74

Rapid Column Extraction Method for Actinides and Sr-89/90 in Water Samples  

SciTech Connect

The SRS Environmental Laboratory analyzes water samples for environmental monitoring, including river water and ground water samples. A new, faster actinide and strontium 89/90 separation method has been developed and implemented to improve productivity, reduce labor costs and add capacity to this laboratory. This method uses stacked TEVA Resin{reg_sign}, TRU Resin{reg_sign} and Sr-Resin{reg_sign} cartridges from Eichrom Technologies (Darien, IL, USA) that allows the rapid separation of plutonium (Pu), neptunium (Np), uranium (U), americium (Am), curium (Cm) and thorium (Th) using a single multi-stage column combined with alpha spectrometry. By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized. The method can be used for routine analysis or as a rapid method for emergency preparedness. Thorium and curium are often analyzed separately due to the interference of the daughter of Th-229 tracer, actinium (Ac)-225, on curium isotopes when measured by alpha spectrometry. This new method also adds a separation step using DGA Resin{reg_sign}, (Diglycolamide Resin, Eichrom Technologies) to remove Ac-225 and allow the separation and analysis of thorium isotopes and curium isotopes at the same time.

MAXWELL III, SHERROD L.

2005-06-15

75

Extraction of squalene from shark liver oil in a packed column using supercritical carbon dioxide  

SciTech Connect

Continuous extraction of squalene from shark liver oil using supercritical carbon dioxide was carried out in both laboratory and pilot scale plant. The shark liver oil contained around 50% by weight squalene, which was recovered as the main extract stream. The other major components in the oil were triglycerides, which were recovered as raffinate, and pristane, which was recovered as a second extract stream. Separation performance was determined as a function of temperature; pressure; oil to carbon dioxide flow rate ratio, packed height and type of packing; and reflux ratio. The pressure, temperature, and feed oil concentration of squalene determined the maximum loading of oil in carbon dioxide. The oil to carbon dioxide ratio determined the squalene concentration in both the product stream and raffinate stream. The ratio of oil flow rate to the flow rate of squalene required to just saturate carbon dioxide was found to be a useful correlating parameter for the oil loadings and product compositions. Of the three packings investigated, wire wool gave the best separation efficiency and Raschig rings the worst efficiency. Mass transfer correlations from the literature were used to estimate the number of transfer units (NTU) from experimental data and literature correlations. NTU`s from the experimental data were comparable to predictions at a pilot scale but were underpredicted at the laboratory scale. The use of reflux at the pilot scale enabled the concentration of squalene in the product stream to be increased from 92% by mass to a maximum of 99% by mass at fractionation conditions of 250 bar and 333 K.

Catchpole, O.J.; Kamp, J.C. von; Grey, J.B. [Industrial Research Limited, Lower Hutt (New Zealand)] [Industrial Research Limited, Lower Hutt (New Zealand)

1997-10-01

76

Characterization of a high-pressure laser ion source with dc and pulsed extraction  

NASA Astrophysics Data System (ADS)

The Dublin City University (DCU) laser ion source (LIS) is a compact, high-throughput system which utilizes a very short field-free region (L = 4.8 cm) so ion extraction at the anode occurs at 'high pressure'. Detailed studies of the system performance are reported here for a range of laser power densities (Ip ~ (0.35-2.4) × 1011 W cm-2) and extraction voltages (dc 5-17 kV, pulsed 15-40 kV). Extracted ion beam currents were measured with the aid of a Faraday cup and ranged from ~3.2 mA (Cu2+) to 0.1 mA (Cu6+). Pronounced turning points in the current profiles were observed for both dc and pulsed extraction, related to so-called 'plasma bulge' at the anode which in turn has its origins in the high plasma density at extraction. The kinetic energy of Cu2+ ions was quantified for a range of extraction bias values and used to determine the extraction efficiency. A planar probe, employed to measure the radial profile of the ion beam, yielded minimum beam diameters of ~6-8 mm for Cu+ and Cu2+. These data were used to determine the collected current density J, which peaked at 1.92 mA cm-2. Using a gated intensified charge coupled device camera, the internal structure of the extracted ion bunches was imaged and ion number densities estimated. The dependence of other key beam parameters on focusing optics, laser energy and extraction voltage was also investigated.

Yeates, P.; Costello, J. T.; Kennedy, E. T.

2010-12-01

77

Simulating ion beam extraction from a single aperture triode acceleration column: A comparison of the beam transport codes IGUN and PBGUNS with test stand data  

SciTech Connect

Ion beam extraction from two different ion sources with single aperture triode extraction columns was simulated with the particle beam transport codes PBGUNS and IGUN. For each ion source, the simulation results are compared to experimental data generated on well-equipped test stands. Both codes reproduced the qualitative behavior of the extracted ion beams to incremental and scaled changes to the extraction electrode geometry observed on the test stands. Numerical values of optimum beam currents and beam emittance generated by the simulations also agree well with test stand data.

Patel, A.; Wills, J. S. C.; Diamond, W. T. [Chalk River Laboratories, AECL, Chalk River, Ontario K0 J 1J0 (Canada)

2008-04-15

78

Determination of Wastewater Compounds in Sediment and Soil by Pressurized Solvent Extraction, Solid-Phase Extraction, and Capillary-Column Gas Chromatography/Mass Spectrometry  

USGS Publications Warehouse

A method for the determination of 61 compounds in environmental sediment and soil samples is described. The method was developed in response to increasing concern over the effects of endocrine-disrupting chemicals in wastewater and wastewater-impacted sediment on aquatic organisms. This method also may be used to evaluate the effects of combined sanitary and storm-sewer overflow on the water and sediment quality of urban streams. Method development focused on the determination of compounds that were chosen on the basis of their endocrine-disrupting potential or toxicity. These compounds include the alkylphenol ethoxylate nonionic surfactants and their degradates, food additives, fragrances, antioxidants, flame retardants, plasticizers, industrial solvents, disinfectants, fecal sterols, polycyclic aromatic hydrocarbons, and high-use domestic pesticides. Sediment and soil samples are extracted using a pressurized solvent extraction system. The compounds of interest are extracted from interfering matrix components by high-pressure water/isopropyl alcohol extraction. The compounds were isolated using disposable solid-phase extraction (SPE) cartridges containing chemically modified polystyrene-divinylbenzene resin. The cartridges were dried with nitrogen gas, and then sorbed compounds were eluted with methylene chloride (80 percent)-diethyl ether (20 percent) through Florisil/sodium sulfate SPE cartridge, and then determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-sand samples fortified at 4 to 72 micrograms averaged 76 percent ?13 percent relative standard deviation for all method compounds. Initial method reporting levels for single-component compounds ranged from 50 to 500 micrograms per kilogram. The concentrations of 20 out of 61 compounds initially will be reported as estimated with the 'E' remark code for one of three reasons: (1) unacceptably low-biased recovery (less than 60 percent) or highly variable method performance (greater than 25 percent relative standard deviation), (2) reference standards prepared from technical mixtures, or (3) potential blank contamination. Samples were preserved by freezing to -20 degrees Celsius. The U.S. Geological Survey National Water Quality Laboratory has established a 1-year sample-holding time limit (prior to sample extraction) from the date of sample collection (if the sample is kept at -20?C) until a statistically accepted method can be used to determine the effectiveness of the sample-freezing procedure.

Burkhardt, Mark R.; Zaugg, Steven D.; Smith, Steven G.; ReVello, Rhiannon C.

2006-01-01

79

Preparation and characterization of a water-soluble fraction of crude oil by a Karr reciprocating-plate countercurrent extraction column  

Microsoft Academic Search

A 1.8 m×2.5 cm reciprocating-plate countercurrent extraction column was evaluated for the preparation of WSF (water-soluble fractions) from Flotta North Sea light crude oil. The energy input from the plate reciprocation speeds was found to be the main factor affecting the characteristics of the extracted WSF, and the throughputs of the stock solution or the ratio of seawater to crude

S. Zhou; H. Heras; R. G. Ackman

1994-01-01

80

Adaptive pulsed laser line extraction for terrain reconstruction using a dynamic vision sensor.  

PubMed

Mobile robots need to know the terrain in which they are moving for path planning and obstacle avoidance. This paper proposes the combination of a bio-inspired, redundancy-suppressing dynamic vision sensor (DVS) with a pulsed line laser to allow fast terrain reconstruction. A stable laser stripe extraction is achieved by exploiting the sensor's ability to capture the temporal dynamics in a scene. An adaptive temporal filter for the sensor output allows a reliable reconstruction of 3D terrain surfaces. Laser stripe extractions up to pulsing frequencies of 500 Hz were achieved using a line laser of 3 mW at a distance of 45 cm using an event-based algorithm that exploits the sparseness of the sensor output. As a proof of concept, unstructured rapid prototype terrain samples have been successfully reconstructed with an accuracy of 2 mm. PMID:24478619

Brandli, Christian; Mantel, Thomas A; Hutter, Marco; Höpflinger, Markus A; Berner, Raphael; Siegwart, Roland; Delbruck, Tobi

2013-01-01

81

Adaptive pulsed laser line extraction for terrain reconstruction using a dynamic vision sensor  

PubMed Central

Mobile robots need to know the terrain in which they are moving for path planning and obstacle avoidance. This paper proposes the combination of a bio-inspired, redundancy-suppressing dynamic vision sensor (DVS) with a pulsed line laser to allow fast terrain reconstruction. A stable laser stripe extraction is achieved by exploiting the sensor's ability to capture the temporal dynamics in a scene. An adaptive temporal filter for the sensor output allows a reliable reconstruction of 3D terrain surfaces. Laser stripe extractions up to pulsing frequencies of 500 Hz were achieved using a line laser of 3 mW at a distance of 45 cm using an event-based algorithm that exploits the sparseness of the sensor output. As a proof of concept, unstructured rapid prototype terrain samples have been successfully reconstructed with an accuracy of 2 mm. PMID:24478619

Brandli, Christian; Mantel, Thomas A.; Hutter, Marco; Höpflinger, Markus A.; Berner, Raphael; Siegwart, Roland; Delbruck, Tobi

2014-01-01

82

Solid state switch application for the LHC extraction kicker pulse generator  

Microsoft Academic Search

A semiconductor solid state switch has been constructed and tested in the prototype extraction kicker pulse generator of CERN's Large Hadron Collider (LHC). The switch is made of 10 modified 4.5 kV, 66 mm symmetric GTOs (also called FHCT-fast high current thyristor), connected in series. It holds off a DC voltage of 30 kV and conducts a 5 ?s half-sine

E. Carlier; L. Ducimetiere; U. Jansson; M. Schlaug; G. Schroder; Eugčne B Vossenberg

1996-01-01

83

Extracting breathing rate information from a wearable reflectance pulse oximeter sensor.  

PubMed

The integration of multiple vital physiological measurements could help combat medics and field commanders to better predict a soldier's health condition and enhance their ability to perform remote triage procedures. In this paper we demonstrate the feasibility of extracting accurate breathing rate information from a photoplethysmographic signal that was recorded by a reflectance pulse oximeter sensor mounted on the forehead and subsequently processed by a simple time domain filtering and frequency domain Fourier analysis. PMID:17271561

Johnston, W S; Mendelson, Y

2004-01-01

84

Separation of the Components of a Commercial Analgesic Tablet: A Two-Week Sequence Comparing Purification by Two-Base Extraction and Column Chromatography  

ERIC Educational Resources Information Center

A new laboratory experiment is described in which students compare two benchtop separation methods to isolate the three active components of the commercial analgesic Excedrin. In the two-week sequence, aspirin, acetaminophen, and caffeine are separated using either a two-base liquid-liquid extraction or silica column chromatography. Students then…

Revell, Kevin D.

2011-01-01

85

Pulsed Ultraviolet Light Reduces Immunoglobulin E Binding to Atlantic White Shrimp (Litopenaeus setiferus) Extract  

PubMed Central

Pulsed ultraviolet light (PUV), a novel food processing and preservation technology, has been shown to reduce allergen levels in peanut and soybean samples. In this study, the efficacy of using PUV to reduce the reactivity of the major shrimp allergen, tropomyosin (36-kDa), and to attenuate immunoglobulin E (IgE) binding to shrimp extract was examined. Atlantic white shrimp (Litopenaeus setiferus) extract was treated with PUV (3 pulses/s, 10 cm from light source) for 4 min. Tropomyosin was compared in the untreated, boiled, PUV-treated and [boiled+PUV]-treated samples, and changes in the tropomyosin levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). IgE binding of the treated extract was analyzed via immunoblot and enzyme-linked immunosorbent assay (ELISA) using pooled human plasma containing IgE antibodies against shrimp allergens. Results showed that levels of tropomyosin and IgE binding were reduced following PUV treatment. However, boiling increased IgE binding, while PUV treatment could offset the increased allergen reactivity caused by boiling. In conclusion, PUV treatment reduced the reactivity of the major shrimp allergen, tropomyosin, and decreased the IgE binding capacity of the shrimp extract. PMID:21845146

Shriver, Sandra; Yang, Wade; Chung, Si-Yin; Percival, Susan

2011-01-01

86

Phytochemical analysis of ethanolic extract of Dichrostachys Cinerea W and Arn leaves by a thin layer chromatography, high performance thin layer chromatography and column chromatography  

PubMed Central

Background: The leaves of Dichrostachys cinerea are used as laxative, diuretic, painkiller. It is also used in the treatment of gonorrhoea, boils, oedema, gout, veneral diseases and nasopharyngeal affections, etc. Materials and Methods: The Phytochemical investigation of ethanolic extract of D. cinerea leaves were performed by standard chemical tests, thin layer chromatography (TLC) by using various solvent systems, and by high performance liquid chromatography (HPTLC). Two compounds were isolated by column chromatography and one of the compounds was identified by various spectral studies. Result: Preliminary phytochemical screening of ethanolic extract of D. cinerea leaves showed the presence of Carbohydrates, proteins, Glycosides, Saponins, Tannins, Aminoacids and Terpenoids. The TLC and HPTLC fingerprint of ethanolic extract were studied and various fractions were isolated by column chromatography and one of the fraction contain ?-amyrin glucoside which was confirmed by Infra Red[IR] Spectroscopy, 1H-Nuclear Magnetic Resonance (NMR), C-13 NMR and Mass spectroscopic (MS) studies. PMID:24991072

Vijayalakshmi, M.; Periyanayagam, K.; Kavitha, K.; Akilandeshwari, K.

2013-01-01

87

Comparison of analytical and semi-preparative columns for high-performance liquid chromatography-solid-phase extraction-nuclear magnetic resonance.  

PubMed

The application of analytical and semi-preparative columns in reversed-phase liquid chromatography-solid-phase extraction-nuclear magnetic resonance (HPLC-SPE-NMR) was compared. The work was aiming at separating a higher sample amount in a single run and in this way to reduce the necessary NMR measurement time of separated compounds. Several parameters for compound separation and trapping procedures were optimised: flow rate of HPLC and make-up water pumps, choice of stationary phase cartridges and drying time. The separation and loadability of nine model compounds on analytical and semi-preparative columns was determined, as well as the focussing capacity of SH-type SPE cartridges. It was found that a semi-preparative column--or multiple peak trapping on analytical columns--gave better results than a standard 4.6mm analytical column for non-polar compounds (e.g. flavonoid aglycones, sesquiterpene lactones, non-polar terpenes, logP>2), but for polar compounds (logP<-2) did not offer any advantage over an analytical column, or was even disadvantageous. For intermediately polar compounds (-2

Miliauskas, Giedrius; van Beek, Teris A; de Waard, Pieter; Venskutonis, Rimantas P; Sudhölter, Ernst J R

2006-04-21

88

Structural information extracted from the diffraction of XFEL fs-pulses in a crystal  

E-print Network

We present a theoretical justification for a method of extracting of supplementary information for the phase retrieval procedure taken from diffraction of fs-pulses from X-ray Free Electron Laser facilities. The approach is based on numerical simulation of the dynamics of the electron density in the crystal composed of different atoms in the unit cell, namely a bi-atomic crystal containing heavy and light atoms. It is shown that evaluation of diffraction intensities measured by means of different values of XFEL pulse parameters enables to find absolute values of structure factors for both types of atoms and their relative phase. The accuracy of structural information is discussed in terms of fluctuations of the evaluated atomic scattering factors. Our approach could be important for improvement of phase retrieval methods with respect to a more efficient determination of atomic positions within the unit cell of macromolecules.

Leonov, A; Benediktovitch, A; Feranchuk, I; Pietsch, U

2015-01-01

89

Gradient HPLC of samples extracted from the green microalga Botryococcus braunii using highly efficient columns packed with 2.6 ?m Kinetex-C?? core-shell particles.  

PubMed

The analysis of the nonpolar extract of the cells of colonies of the green colonial microalgae Botryococcus braunii was performed by gradient HPLC. The growth of B. braunii was stressed by reducing its nitrogen nutrients by 90%, in order to enhance the production of nonpolar compounds. Highly efficient 4.6mm × 100mm columns packed with 2.6 ?m Kinetex-C(18) core-shell particles (Phenomenex, Torrance, CA, USA) were used. The gradient mobile phase was a mixture of acetonitrile and water (70-97%, v/v). Its initial and final compositions during the gradient elution were chosen so that the retention factors of the last eluted compound at the inlet and outlet of the column were 15 and 1, respectively. The highest peak capacity was obtained by optimizing several experimental parameters, including the injected sample volume, the flow rate, and the column length. The highest resolution was obtained by connecting one 4.6 mm × 150 mm and three 4.6mm × 100mm columns (total length 45 cm). The optimum flow rate was 1.5 mL/min, which provided the minimum plate height for the most retained compounds, the optimum inlet pressure was 930 bar and the injected volume 2 ?L. The analysis time was then 14 min for a peak capacity of 121. The trends observed for the variation of the experimental peak capacity with the flow rate and the column length are in excellent agreement with theoretical predictions. PMID:22307155

Gritti, Fabrice; Perdu, Marie-Agnčs; Guiochon, Georges

2012-03-16

90

On-line liquid-liquid extraction in a segmented flow directly coupled to on-column injection into a gas chromatograph  

SciTech Connect

A mechanized system for extractive sample workup for gas chromatography coupled on-line to an on-column injector is described. Extraction is performed in a liquid-liquid segmented flow in a glass coil internally coated with a hydrophobic layer. After extraction the phases are separated with the aid of a hydrophobic membrane supported by a screen coated with Teflon. The organic phase is fed to a loop injector. The system is closed from the atmosphere and was proven to provide rapid and precise workup of seawater samples of the determination of the halocarbons chloroform, bromodichloromethane, dibromochloromethane, bromoform, trichloroethylene, tetrachloroethylene, carbon tetrachloride, and 1,1,1-trichloroethane. Compared to manual extraction, smaller volumes of sample and organic phase are needed. Reliability was tested during a 3-week cruise when 350 seawater samples were processed without system failure. Concentrations down to the picogram-per-liter level in water can be determined, using injection volumes up to 130 /sup +/L.

Fogelqvist, E.; Krysell, M.; Danielsson, L.G.

1986-06-01

91

Expanding the potential of standard flow cytometry by extracting fluorescence lifetimes from cytometric pulse shifts  

PubMed Central

Fluorescence lifetime measurements provide information about the fluorescence relaxation, or intensity decay, of organic fluorophores, fluorescent proteins, and other inorganic molecules that fluoresce. The fluorescence lifetime is emerging in flow cytometry and is helpful in a variety of multiparametric, single cell measurements because it is not impacted by nonlinearity that can occur with fluorescence intensity measurements. Yet time-resolved cytometry systems rely on major hardware modifications making the methodology difficult to reproduce. The motivation of this work is, by taking advantage of the dynamic nature of flow cytometry sample detection and applying digital signal processing methods, to measure fluorescence lifetimes using an unmodified flow cytometer. We collect a new lifetime-dependent parameter, referred to herein as the fluorescence-pulse-delay (FPD), and prove it is a valid representation of the average fluorescence lifetime. To verify we generated cytometric pulses in simulation, with light emitting diode (LED) pulsation, and with true fluorescence measurements of cells and microspheres. Each pulse is digitized and used in algorithms to extract an average fluorescence lifetime inherent in the signal. A range of fluorescence lifetimes is measurable with this approach including standard organic fluorophore lifetimes (?1 to 22 ns) as well as small, simulated shifts (0.1 ns) under standard conditions (reported herein). This contribution demonstrates how digital data acquisition and signal processing can reveal time-dependent information foreshadowing the exploitation of full waveform analysis for quantification of similar photo-physical events within single cells. © 2014 The Authors. Published by Wiley Periodicals, Inc. PMID:25274073

Cao, Ruofan; Naivar, Mark A; Wilder, Mark; Houston, Jessica P

2014-01-01

92

The effect of dilution and the use of a post-extraction nucleic acid purification column on the accuracy, precision, and inhibition of environmental DNA samples  

USGS Publications Warehouse

Isolation of environmental DNA (eDNA) is an increasingly common method for detecting presence and assessing relative abundance of rare or elusive species in aquatic systems via the isolation of DNA from environmental samples and the amplification of species-specific sequences using quantitative PCR (qPCR). Co-extracted substances that inhibit qPCR can lead to inaccurate results and subsequent misinterpretation about a species’ status in the tested system. We tested three treatments (5-fold and 10-fold dilutions, and spin-column purification) for reducing qPCR inhibition from 21 partially and fully inhibited eDNA samples collected from coastal plain wetlands and mountain headwater streams in the southeastern USA. All treatments reduced the concentration of DNA in the samples. However, column purified samples retained the greatest sensitivity. For stream samples, all three treatments effectively reduced qPCR inhibition. However, for wetland samples, the 5-fold dilution was less effective than other treatments. Quantitative PCR results for column purified samples were more precise than the 5-fold and 10-fold dilutions by 2.2× and 3.7×, respectively. Column purified samples consistently underestimated qPCR-based DNA concentrations by approximately 25%, whereas the directional bias in qPCR-based DNA concentration estimates differed between stream and wetland samples for both dilution treatments. While the directional bias of qPCR-based DNA concentration estimates differed among treatments and locations, the magnitude of inaccuracy did not. Our results suggest that 10-fold dilution and column purification effectively reduce qPCR inhibition in mountain headwater stream and coastal plain wetland eDNA samples, and if applied to all samples in a study, column purification may provide the most accurate relative qPCR-based DNA concentrations estimates while retaining the greatest assay sensitivity.

Mckee, Anna M.; Spear, Stephen F.; Pierson, Todd W.

2014-01-01

93

Cooling of extraction electrode of an ion source in long-pulse operation.  

PubMed

Experimental studies were made on the cooling of extraction electrodes of an ion source in the case of long-pulse operation. Copper electrodes with forced water cooling pipes were tested under the condition that an ion beam of 1 to 5 A at 30 keV was extracted for up to 10 s. The average heat loading to the grid are of the electrode was as high as 130 W/cm2. This high heat flux was obtained by a set of electrodes artificially arranged to produce poor beam optics, and hence the high heat loading. Temperature of the ground electrode was measured at two points by thermocouples buried and silver brazed in it, and was kept below 230 degrees C due to a large boiling heat transfer coefficient of the cooling water. No evidences of deformation or deterioration of the electrodes was observed after repetitious beam extraction. This heat loading was still a half of that on the grid of the ion source for the JT-60 NBI. PMID:18699409

Horiike, H; Kondoh, U; Morita, H; Shirakata, H; Sugawara, T; Tanaka, S

1979-11-01

94

Propagation of a surface microwave along the afterglow plasma column of a high-current pulsed discharge  

NASA Astrophysics Data System (ADS)

It is demonstrated experimentally that the lifetime of the afterglow plasma of a high-current pulsed discharge in a dielectric tube filled with a mixture of argon with saturated mercury vapor is longer than 1 ms. Such a long lifetime, during which the electron density decreases from 1014 to 1012 cm-3, is explained by the chemi-ionization of mercury vapor by long-lived metastable argon atoms. During this time, the afterglow plasma can serve as a microwave waveguide for a weakly damped low-noise E 0-type axisymmetric surface mode, which allows one to use it for transmission of signals in the centimeter wavelength range.

Sergeichev, K. F.; Karfidov, D. M.

2011-09-01

95

Monolithic silica spin column extraction and simultaneous derivatization of amphetamines and 3,4-methylenedioxyamphetamines in human urine for gas chromatographic-mass spectrometric detection.  

PubMed

A simple, sensitive, and specific method with gas chromatography-mass spectrometry was developed for simultaneous extraction and derivatization of amphetamines (APs) and 3,4-methylenedioxyamphetamines (MDAs) in human urine by using a monolithic silica spin column. All the procedures, such as sample loading, washing, and elution were performed by centrifugation. APs and MDAs in urine were adsorbed on the monolithic silica and derivatized with propyl chloroformate in the column. Methamphetamine-d(5) was used as an internal standard. The linear ranges were 0.01-5.0 microg mL(-1) for methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA) and 0.02-5.0 microg mL(-1) for amphetamine (AP) and 3,4-methylenedioxyamphetamine (MDA) (coefficient of correlation > or = 0.995). The recovery of APs and MDAs in urine was 84-94%, and the relative standard deviation of the intra- and interday reproducibility for urine samples containing 0.1, 1.0, and 4.0 microg mL(-1) of APs and MDAs ranged from 1.4% to 13.6%. The lowest detection limit (signal-to-noise ratio > or = 3) in urine was 5 ng mL(-1) for MA and MDMA and 10 ng mL(-1) for AP and MDA. The proposed method can be used to perform simultaneous extraction and derivatization on spin columns that have been loaded with a small quantity of solvent by using centrifugation. PMID:20113714

Nakamoto, Akihiro; Nishida, Manami; Saito, Takeshi; Kishiyama, Izumi; Miyazaki, Shota; Murakami, Katsunori; Nagao, Masataka; Namura, Akira

2010-02-19

96

Rapid trace level determination of sulfonamide residues in honey with online extraction using short C-18 column by high-performance liquid chromatography with fluorescence detection.  

PubMed

A sensitive and inexpensive quantification method with online extraction using a short C-18 column for sulfonamide residues in honey by high performance liquid chromatography with fluorescence detector was developed and validated. In sample preparation, acid hydrolysis was used to break the N-glycoside bond between the honey sugar and sulfonamide drugs and derivatization of sulfonamide residues with fluorescamine was conducted at pH 3.5 using a citrate buffer (0.5M) in the honey matrix. The chromatography was carried out on Zorbax Extended C-18 (250mm×4.6mm; 5?m) column, using a mixture of acetonitrile and an acetate buffer (pH 4.50, 20mM) as a mobile phase. A Zorbax Extended C-18 (12mm×4.6mm; 5?m) column was used for online extraction of fifteen sulfonamide residues from honey sample with the help of a two position valve. The limit of quantification of sulfonamide residues in honey was less than 3ngg(-1), and the percentage recovery of study compounds in spiked honey sample was from 80% for sulfacetamide to 100% of sulfachloropyridazine. The developed method has excellent linearity for all studied sulfonamides with a correlation coefficient 0.993. PMID:24055224

Sajid, Muhammad; Na, Na; Safdar, Muhammad; Lu, Xin; Ma, Lin; He, Lan; Ouyang, Jin

2013-11-01

97

Cold column trapping-cloud point extraction coupled to high performance liquid chromatography for preconcentration and determination of curcumin in human urine.  

PubMed

A cold column trapping-cloud point extraction (CCT-CPE) method coupled to high performance liquid chromatography (HPLC) was developed for preconcentration and determination of curcumin in human urine. A nonionic surfactant, Triton X-100, was used as the extraction medium. In the proposed method, a low surfactant concentration of 0.4% v/v and a short heating time of only 2min at 70°C were sufficient for quantitative extraction of the analyte. For the separation of the extraction phase, the resulted cloudy solution was passed through a packed trapping column that was cooled to 0?°C. The temperature of the CCT column was then increased to 25°C and the surfactant rich phase was desorbed with 400?L ethanol to be directly injected into HPLC for the analysis. The effects of different variables such as pH, surfactant concentration, cloud point temperature and time were investigated and optimum conditions were established by a central composite design (response surface) method. A limit of detection of 0.066mgL(-1) curcumin and a linear range of 0.22-100mgL(-1) with a determination coefficient of 0.9998 were obtained for the method. The average recovery and relative standard deviation for six replicated analysis were 101.0% and 2.77%, respectively. The CCT-CPE technique was faster than a conventional CPE method requiring a lower concentration of the surfactant and lower temperatures with no need for the centrifugation. The proposed method was successfully applied to the analysis of curcumin in human urine samples. PMID:24793851

Rahimi, Marzieh; Hashemi, Payman; Nazari, Fariba

2014-05-15

98

Automated determination of total captopril in urine by liquid chromatography with post-column derivatization coupled to on-line solid phase extraction in a sequential injection manifold.  

PubMed

The present study reports a new liquid chromatographic (HPLC) method for the determination of the anti-hypertension drug captopril (CAP) in human urine. After its separation from the sample matrix in a reversed phase HPLC column, CAP reacts with the thiol-selective reagent ethyl-propiolate (EP) in a post-column configuration and the formed thioacrylate derivative is detected at 285 nm. Automated 4-fold preconcentration of the analyte prior to analysis was achieved by an on-line solid phase extraction (SPE) step using a sequential injection (SI) manifold. The Oasis HLB SPE cartridges offered quantitative recoveries and effective sample cleaning by applying a simple SPE protocol. The limits of detection and quantitation were 10 ?g L(-1) and 35 ?g L(-1) respectively. The percent recoveries for the analysis of human urine samples ranged between 90 and 96% and 95 and 104% using aqueous and matrix matched calibration curves respectively. PMID:22265541

Karakosta, Theano D; Tzanavaras, Paraskevas D; Themelis, Demetrius G

2012-01-15

99

Photoionization of helium by attosecond pulses: Extraction of spectra from correlated wave functions  

NASA Astrophysics Data System (ADS)

We investigate the photoionization spectrum of helium by attosecond XUV pulses both in the spectral region of doubly excited resonances as well as above the double ionization threshold. In order to probe for convergence, we compare three techniques to extract photoelectron spectra from the wave packet resulting from the integration of the time-dependent Schrödinger equation in a finite-element discrete variable representation basis. These techniques are projection on products of hydrogenic bound and continuum states, projection onto multichannel scattering states computed in a B-spline close-coupling basis, and a technique based on exterior complex scaling implemented in the same basis used for the time propagation. These methods allow one to monitor the population of continuum states in wave packets created with ultrashort pulses in different regimes. Applications include photo cross sections and anisotropy parameters in the spectral region of doubly excited resonances, time-resolved photoexcitation of autoionizing resonances in an attosecond pump-probe setting, and the energy and angular distribution of correlated wave packets for two-photon double ionization.

Argenti, Luca; Pazourek, Renate; Feist, Johannes; Nagele, Stefan; Liertzer, Matthias; Persson, Emil; Burgdörfer, Joachim; Lindroth, Eva

2013-05-01

100

Propagation of a surface microwave along the afterglow plasma column of a high-current pulsed discharge  

SciTech Connect

It is demonstrated experimentally that the lifetime of the afterglow plasma of a high-current pulsed discharge in a dielectric tube filled with a mixture of argon with saturated mercury vapor is longer than 1 ms. Such a long lifetime, during which the electron density decreases from 10{sup 14} to 10{sup 12} cm{sup -3}, is explained by the chemi-ionization of mercury vapor by long-lived metastable argon atoms. During this time, the afterglow plasma can serve as a microwave waveguide for a weakly damped low-noise E{sub 0}-type axisymmetric surface mode, which allows one to use it for transmission of signals in the centimeter wavelength range.

Sergeichev, K. F.; Karfidov, D. M. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

2011-09-15

101

On-line hyphenation of solid-phase extraction to chromatographic separation of sulfonamides with fused-core columns in sequential injection chromatography.  

PubMed

On-line sample pretreatment (clean-up and analyte preconcentration) is for the first time coupled to sequential injection chromatography. The approach combines anion-exchange solid-phase extraction and the highly effective pentafluorophenylpropyl (F5) fused-core particle column for separation of eight sulfonamide antibiotics with similar structures (sulfathiazole, sulfanilamide, sulfacetamide, sulfadiazine, sulfamerazine, sulfadimidine, sulfamethoxazole and sulfadimethoxine). The stationary phase was selected after a critical comparison of the performance achieved by three fused-core reversed phase columns (Ascentis(®) Express RP-Amide, Phenyl-Hexyl, and F5) and two monolithic columns (Chromolith(®) High Resolution RP-18 and CN). Acetonitrile and acetate buffer pH 5.0 at 0.60 mL min(-1) were used as mobile phase to perform the separations before spectrophotometric detection. The first mobile phase was successfully used as eluent from SPE column ensuring transfer of a narrow zone to the chromatographic column. Enrichment factors up to 39.2 were achieved with a 500 µL sample volume. The developed procedure showed analysis time <10.5 min, resolutions >1.83 with peak symmetry ?1.52, LODs between 4.9 and 27 µg L(-1), linear response ranges from 30.0 to 1000.0 µg L(-1) (r(2)>0.996) and RSDs of peak heights <2.9% (n=6) at a 100 µg L(-1) level and enabled the screening control of freshwater samples contaminated at the 100 µg L(-1) level. The proposed approach expanded the analytical potentiality of SIC and avoided the time-consuming batch sample pretreatment step, thus minimizing risks of sample contamination and analyte losses. PMID:25435240

Batista, Alex D; Chocholouš, Petr; Satínský, Dalibor; Solich, Petr; Rocha, Fábio R P

2015-02-01

102

Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption in the ASCENDS 2011 Airborne Campaign: Measurement Analysis  

NASA Astrophysics Data System (ADS)

Trace gas LIDAR has the potential to actively sense greenhouse gas concentrations in the earth's atmosphere continuously without being affected by day or night. This will enable identifying greenhouse gas sources and sinks, which will help better predict future atmospheric trends of these gases. However, in order to ensure reliable and accurate measurements, it is important to establish metrics to quantify performance. As part of the ASCENDS (Active Sensing of Co2 over Nights, Days and Seasons) program, we conducted an airborne campaign of our CO2 pulsed LIDAR system in August 2011, flying over a variety of terrain and conditions, including snow, ocean, clouds, desert and mountains. Our instrument uses an IPDA (Integrated Path Differential Absorption) approach probing 30 wavelengths across a 1572 nm CO2 absorption line. Our multi-wavelength approach provides redundancy for evaluating the stability of the instrument, and also allows us to perform spectroscopic analysis of the atmosphere. Here, we present our detailed analysis and results. Tracking long-term stability of our instrument by using the Allan deviation formalism for wavelengths away from the absorption line-center, we find that the measured pulse energy (normalized to eliminate ground reflectivity) is stable down to 0.2% across varying terrain, surface reflectivity, flight altitude and LIDAR range. Comparing our measured CO2 absorption line-shape (at regions of constant, known CO2 concentrations) with the predicted line-shape based on the LIDAR range, flight altitude and relevant atmosphere parameters (based on in situ measurements by instruments aboard the aircraft), we find the agreement to be better than 1% (RMS error), once we average 50 s to eliminate shot noise. Our multi-wavelength approach also allows us to track the position of the line-center. The altitude dependence of the atmospheric pressure causes a shift in the CO2 absorption as a function of aircraft altitude. Our measured pressure shift agrees with the predicted shift to within 0.005 pm (RMS), the latter spanning 0.7 pm. The 0.2% long-term stability of our instrument, combined with our multi-wavelength approach and the excellent agreement between our predicted and measured absorption profile enables us to accurately retrieve the vertical profile of the atmospheric CO2. Furthermore, with higher laser power and more sensitive detection, we expect to make sensitive measurements of the CO2 concentration in shorter timescales.

Ramanathan, A.; Mao, J.; Allan, G. R.; Weaver, C. J.; Hasselbrack, W.; Riris, H.; Sun, X.; Abshire, J. B.

2012-12-01

103

The use of selective extraction chromatographic columns as an alternative to solvent extraction for the separation of uranium followed by the use of Arsenazo III as a calorimetric reagent for uranium determination  

SciTech Connect

The use of U/TEVA{reg_sign} Spec columns as an alternative to solvent extraction for separation of uranium prior to its determination by various techniques (calorimetric, phosphorescence, and mass spectroscopy) was investigated. U/TEVA{reg_sign} Spec columns have several advantages over the widely used 4-methyl-2-pentanone solvent extraction method. Among the advantages are: (1) no hazardous liquid organic waste, that creates regulatory waste disposal problems, is generated; (2) a clean separation of U from Zr, F, and fission products is obtained; (3) the sample preparation time is reduced; and (4) the exposure of analysts to ionizing radiation is reduced because the entire procedure may be performed in a hot cell using remote operations. This study also investigated the use of Arsenazo III (1,8-dihydroxynapthalene-3,6-disulfonic acid-2,7-bis [<-azo-2>-phenylarsonic acid]) as a calorimetric reagent to determine uranium concentrations over a wide range in waste streams and product streams at the Idaho Chemical Processing Plant. Process and waste stream samples were passed through a U/TEVA{reg_sign} Spec column to selectively remove the uranium. The uranium bearing fraction is compatible with the pH range for color development with Arsenazo III. Arsenazo III may be added to the uranium fraction, at a 3:1 mole ratio (Arsenazo:Uranium) at the high end of the method (10 {mu}/mL). Arsenazo III forms a highly stable complex with uranium. Stability tests from this and other studies show that the colored complex of Arsenazo III with U(VI) forms within one minute and remains stable for several hours. The complex with U(VI) varies in color with pH. However, with excess reagent, the color is varying shades of purple. Since the samples were passed through a highly selective extraction chromatographic column prior to adding the calorimetric reagent, no interferences were observed.

Miller, C.J.; Del Mastro, J.R.

1994-10-01

104

Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its ion-association complex with cetyltrimethylammoniumbromide on an alumina column.  

PubMed

A simple approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its ion-association complex with cetyltrimethylammoniumbromide (CTABr) on an alumina column. The effect of various parameters such as acidity, stability of the column, sample volume, effect of diverse ions, etc. have been studied in detail. The adsorbed complex could be eluted using sodium hydroxide and the concentration of chromium has been established using visible spectrophotometry after complexation with diphenyl carbazide. The calibration graph was linear in the range 0-0.5 microg mL(-1) chromium(VI) with a detection limit of 5 microg L(-1). A highest preconcentration factor of 25 could be obtained for 250 mL sample volume. The data from the column studies were also studied using the Thomas model of adsorption. The experimental results obtained were correlated with the proposed model of adsorption. The Thomas rate constant k was found to be 0.0025 L/min mg and the maximum adsorption capacity q(o) was found to be 0.36 mgCr/g alumina at an initial chromium(VI) concentration of 1 mg L(-1). The validity of the method has been checked by applying it to study the recovery of chromium in spiked water samples and electroplating wastewater. PMID:17126483

Rajesh, N; Deepthi, B; Subramaniam, Archana

2007-06-01

105

On-line SPE-UHPLC method using fused core columns for extraction and separation of nine illegal dyes in chilli-containing spices.  

PubMed

The presented work describes the development of a simple, fast and effective on-line SPE-UHPLC-UV/vis method using fused core particle columns for extraction, separation and quantitative analysis of the nine illegal dyes, most frequently found in chilli-containing spices. The red dyes Sudan I-IV, Sudan Red 7B, Sudan Red G, Sudan Orange G, Para Red, and Methyl Red were separated and analyzed in less than 9 min without labor-consuming pretreatment procedure. The chromatographic separation was performed on Ascentis Express RP-Amide column with gradient elution using mixture of acetonitrile and water, as a mobile phase at a flow rate of 1.0 mL min(-1) and 55°C of temperature. As SPE sorbent for cleanup and pre-concentration of illegal dyes short guard fused core column Ascentis Express F5 was used. The applicability of proposed method was proven for three different chilli-containing commercial samples. Recoveries for all compounds were between 90% and 108% and relative standard deviation ranged from 1% to 4% for within- and from 2% to 6% for between-day. Limits of detection showed lower values than required by European Union regulations and were in the range of 3.3-10.3 µg L(-1) for standard solutions, 5.6-235.6 µg kg(-1) for chilli-containing spices. PMID:25159432

Khalikova, Maria A; Satínský, Dalibor; Smidrkalová, Tereza; Solich, Petr

2014-12-01

106

The Perils of Pathogen Discovery: Origin of a Novel Parvovirus-Like Hybrid Genome Traced to Nucleic Acid Extraction Spin Columns  

PubMed Central

Next-generation sequencing was used for discovery and de novo assembly of a novel, highly divergent DNA virus at the interface between the Parvoviridae and Circoviridae. The virus, provisionally named parvovirus-like hybrid virus (PHV), is nearly identical by sequence to another DNA virus, NIH-CQV, previously detected in Chinese patients with seronegative (non-A-E) hepatitis. Although we initially detected PHV in a wide range of clinical samples, with all strains sharing ?99% nucleotide and amino acid identity with each other and with NIH-CQV, the exact origin of the virus was eventually traced to contaminated silica-binding spin columns used for nucleic acid extraction. Definitive confirmation of the origin of PHV, and presumably NIH-CQV, was obtained by in-depth analyses of water eluted through contaminated spin columns. Analysis of environmental metagenome libraries detected PHV sequences in coastal marine waters of North America, suggesting that a potential association between PHV and diatoms (algae) that generate the silica matrix used in the spin columns may have resulted in inadvertent viral contamination during manufacture. The confirmation of PHV/NIH-CQV as laboratory reagent contaminants and not bona fide infectious agents of humans underscores the rigorous approach needed to establish the validity of new viral genomes discovered by next-generation sequencing. PMID:24027301

Naccache, Samia N.; Greninger, Alexander L.; Lee, Deanna; Coffey, Lark L.; Phan, Tung; Rein-Weston, Annie; Aronsohn, Andrew; Hackett, John; Delwart, Eric L.

2013-01-01

107

APPLICATION OF COLUMN EXTRACTION METHOD FOR IMPURITIES ANALYSIS ON HB-LINE PLUTONIUM OXIDE IN SUPPORT OF MOX FEED PRODUCT SPECIFICATIONS  

SciTech Connect

The current mission at H-Canyon involves the dissolution of an Alternate Feedstocks 2 (AFS-2) inventory that contains plutonium metal. Once dissolved, HB-Line is tasked with purifying the plutonium solution via anion exchange, precipitating the Pu as oxalate, and calcining to form plutonium oxide (PuO{sub 2}). The PuO{sub 2} will provide feed product for the Mixed Oxide (MOX) Fuel Fabrication Facility, and the anion exchange raffinate will be transferred to H-Canyon. The results presented in this report document the potential success of the RE resin column extraction application on highly concentrated Pu samples to meet MOX feed product specifications. The original 'Hearts Cut' sample required a 10000x dilution to limit instrument drift on the ICP-MS method. The instrument dilution factors improved to 125x and 250x for the sample raffinate and sample eluent, respectively. As noted in the introduction, the significantly lower dilutions help to drop the total MRL for the analyte. Although the spike recoveries were half of expected in the eluent for several key elements, they were between 94-98% after Nd tracer correction. It is seen that the lower ICD limit requirements for the rare earths are attainable because of less dilution. Especially important is the extremely low Ga limit at 0.12 {mu}g/g Pu; an ICP-MS method is now available to accomplish this task on the sample raffinate. While B and V meet the column A limits, further development is needed to meet the column B limits. Even though V remained on the RE resin column, an analysis method is ready for investigation on the ICP-MS, but it does not mean that V cannot be measured on the ICP-ES at a low dilution to meet the column B limits. Furthermore, this column method can be applicable for ICP-ES as shown in Table 3-2, in that it trims the sample of Pu, decreasing and sometimes eliminating Pu spectral interferences.

Jones, M.; Diprete, D.; Wiedenman, B.

2012-03-20

108

Monitoring of enzymatic hydrolysis of starch by microdialysis sampling coupled on-line to anion exchange chromatography and integrated pulsed electrochemical detection using post-column switching  

SciTech Connect

A quantitative evaluation of the hydrolysis of wheat starch using Termamyl, a thermostable {alpha}-amylase, is reported. Data from the monitoring of the hydrolysis of wheat starch indicated that, after 1 h, glucose and maltooligosaccharides up to DP 7 were the main hydrolysis products and thus enabled optimization of a liquefaction step during the production of L-lactic acid. The monitoring system used, both in the on- and off-line mode, was based on continuous flow microdialysis sampling (CFMS) coupled to anion exchange chromatography and integrated pulsed electrochemical detection (IPED). A microdialysis probe equipped with a 5-mm polysulfone (SPS 4005) membrane, with a molecular-weight cut-off of 5 kDa, was used to sample the hydrolysis products of native wheat starch at 90 C. Characteristic fingerpoint separations were achieved by anion exchange chromatography after enzymatic hydrolysis. Post-column switching improved the detection and, consequently, also quantification of the hydrolysates as fouling of the electrode could be reduced. Maltooligosaccharide standards were used for quantification and to verify the elution of the hydrolysates by spiking the off-line samples.

Torto, N.; Gorton, L.; Emneus, J.; Laurell, T. [Univ. of Lund (Sweden)] [Univ. of Lund (Sweden); Marko-Varga, G. [Astra Draco AB, Lund (Sweden). Bioanalytical Chemistry] [Astra Draco AB, Lund (Sweden). Bioanalytical Chemistry; Akerberg, C.; Zacchi, G. [Univ. of Lund (Sweden). Dept. of Chemical Engineering] [Univ. of Lund (Sweden). Dept. of Chemical Engineering; [Lund Inst. of Tech. (Sweden)

1997-12-05

109

Dynamic ultrasound-assisted extraction of colistin from feeds with on-line pre-column derivatization and liquid chromatography-fluorimetric detection.  

PubMed

A dynamic ultrasound-assisted extraction (UAE) method with on-line pre-column derivatization/high performance liquid chromatography (HPLC) and fluorimetric detection is proposed for the analysis of colistin in feed. A flow injection manifold is used for the development of the extraction and derivatization steps and for interfacing them with the separation/detection step, thus providing an on-line approach with the advantage of minimum sample handling. The derivatization was performed with ortho-phthaldialdehyde and 2-mercaptoethanol. The optimum conditions for colistin extraction and formation of the fluorescent derivative have been obtained by experimental design methodology. The use of a high-intensity probe sonication makes UAE an expeditious (7 min versus > 1 h) and efficient (93.1-98.2% versus 87.5-94% of recovery) alternative as compared with extraction using an ultrasonic bath. The within-laboratory reproducibility and repeatability, expressed as percentage of relative standard deviation, were 5.2 and 5.8, respectively. PMID:15794548

Morales-Muńoz, S; de Castro, M D Luque

2005-02-25

110

Manual for the thermal and hydraulic design of direct contact spray columns for use in extracting heat from geothermal brines  

SciTech Connect

This report outlines the current methods being used in the thermal and hydraulic design of spray column type, direct contact heat exchangers. It provides appropriate referenced equations for both preliminary design and detailed performance. The design methods are primarily empirical and are applicable for us in the design of such units for geothermal application and for application with solar ponds. Methods for design, for both preheater and boiler sections of the primary heat exchangers, for direct contact binary powers plants are included. 23 refs., 8 figs.

Jacobs, H.R.

1985-06-01

111

"In situ" extraction of essential oils by use of Dean-Stark glassware and a Vigreux column inside a microwave oven: a procedure for teaching green analytical chemistry.  

PubMed

One of the principal objectives of sustainable and green processing development remains the dissemination and teaching of green chemistry in colleges, high schools, and academic laboratories. This paper describes simple glassware that illustrates the phenomenon of extraction in a conventional microwave oven as energy source and a process for green analytical chemistry. Simple glassware comprising a Dean-Stark apparatus (for extraction of aromatic plant material and recovery of essential oils and distilled water) and a Vigreux column (as an air-cooled condenser inside the microwave oven) was designed as an in-situ extraction vessel inside a microwave oven. The efficiency of this experiment was validated for extraction of essential oils from 30 g fresh orange peel, a by-product in the production of orange juice. Every laboratory throughout the world can use this equipment. The microwave power is 100 W and the irradiation time 15 min. The method is performed at atmospheric pressure without added solvent or water and furnishes essential oils similar to those obtained by conventional hydro or steam distillation. By use of GC-MS, 22 compounds in orange peel were separated and identified; the main compounds were limonene (72.1%), ?-pinene (8.4%), and ?-terpinene (6.9%). This procedure is appropriate for the teaching laboratory, does not require any special microwave equipment, and enables the students to learn the skills of extraction, and chromatographic and spectroscopic analysis. They are also exposed to a dramatic visual example of rapid, sustainable, and green extraction of an essential oil, and are introduced to successful sustainable and green analytical chemistry. PMID:22526656

Chemat, Farid; Perino-Issartier, Sandrine; Petitcolas, Emmanuel; Fernandez, Xavier

2012-08-01

112

Determination of lignin in marine sediment using alkaline cupric oxide oxidation-solid phase extraction-on-column derivatization-gas chromatography  

NASA Astrophysics Data System (ADS)

Lignin serves as one of the most important molecular fossils for tracing Terrestrial Organic Matters (TOMs) in marine environment. Extraction and derivatization of lignin oxidation products (LOPs) are crucial for accurate quantification of lignin in marine sediment. Here we report a modification of the conventional alkaline cupric oxide (CuO) oxidation method, the modification consisting in a solid phase extraction (SPE) and a novel on-column derivatization being employed for better efficiency and reproducibility. In spiking blanks, recoveries with SPE for the LOPs are between 77.84% and 99.57% with relative standard deviations (RSDs) ranging from 0.57% to 8.04% ( n=3), while those with traditional liquid-liquid extraction (LLE) are from 44.52% to 86.16% with RSDs being from 0.53% to 13.14% ( n=3). Moreover, the reproducibility is greatly improved with SPE, with less solvent consumption and shorter processing time. The average efficiency of on-column derivatization for LOPs is 100.8% ± 0.68%, which is significantly higher than those of in-vial or in-syringe derivatization, thus resulting in still less consumption of derivatizing reagents. Lignin in the surface sediments sampled from the south of Yangtze River estuary, China, was determined with the established method. Recoveries of 72.66% to 85.99% with standard deviation less than 0.01mg/10g dry weight are obtained except for p-hydroxyben-zaldehyde. The lignin content ?8 (produced from 10 g dry sediment) in the research area is between 0.231 and 0.587 mg. S/V and C/V ratios (1.028 ± 0.433 and 0.192 ± 0.066, respectively) indicate that the TOMs in this region are originated from a mixture of woody and nonwoody angiosperm plants; the high values of (Ad/Al)v suggest that the TOMs has been highly degraded.

Zhang, Ting; Li, Xianguo; Sun, Shuwen; Lan, Haiqing; Du, Peirui; Wang, Min

2013-03-01

113

Modelling of the positive column of a medium-pressure Cs-Xe dc discharge affected by a millimetre wave pulse  

NASA Astrophysics Data System (ADS)

A time-dependent zero-dimensional kinetic model of the positive column (PC) of a medium-pressure Cs-Xe dc discharge was used to gain a better insight into the physical basics of plasma techniques for imaging and control of millimetre wave (MMW) beams. The model allowed one to study the effect of MMWs on the kinetic and electrical characteristics of the spatially homogeneous PC of a Cs-Xe dc discharge. We computed the PC plasma parameters for 30 Torr and 45 Torr xenon and discharge current densities of about 0.1 A cm-2. First, the dependences of the PC parameters on caesium density were calculated in the case of no MMWs incident on the PC plasma. Then, the temporal evolution of the parameters of the PC plasma affected by a long watt-scale Ka-band MMW pulse was modelled for caesium densities of about 3 × 1012 and 5 × 1012 cm-3. The calculations showed that the electron temperature in the PC plasma attained quasisteady-state values for about 1 µs after the beginning of the MMW pulse. The electron temperature rises by 0.2-0.3 eV as the MMW intensity increases from 0 to 1 W cm-2. The rise time of the electron density decreased with an increase in the MMW intensity W from about 1 ms for W = 0.15 W cm-2 to tens of microseconds for W > 1.5 W cm-2. The steady-state values of the electron density increased in proportion to W, if W < 0.5 W cm-2. They were approximately constant for 0.5 < W < 2 W cm-2 due to the nearly full ionization of caesium atoms in the PC plasma. Efficient xenon excitation and ionization for W > 3 W cm-2 could be a cause of the microwave breakdown of the homogeneous PC plasma. The results of the modelling are in good agreement with the published experimental data.

Gitlin, M. S.; Epstein, I. L.; Lebedev, Yu A.

2013-10-01

114

Monolithic spin column extraction and GC-MS for the simultaneous assay of diquat, paraquat, and fenitrothion in human serum and urine.  

PubMed

We present a method based on monolitic spin column extraction and gas chromatography-mass spectrometry as an analytical method for screening diquat (DQ), paraquat (PQ), and fenitrothion in serum and urine. This method is useful for clinical and forensic toxicological analyses. Recovery of DQ, PQ, and fenitrothion from serum and urine, spiked at concentrations between 0.1, 2.5, 20, and 45 ?g/ml, ranged from 51.3% to 106.1%. Relative standard deviation percentages were between 3.3% and 14.8%. Detection and quantitation limits for serum and urine were 0.025 and 0.05 ?g/ml, respectively, for DQ, 0.1 and 0.1 ?g/ml, respectively, for PQ, and 0.025 and 0.05 ?g/ml, respectively, for fenitrothion. Therefore, these compounds can be detected and quantified in the case of acute poisoning. PMID:21221537

Saito, Takeshi; Fukushima, Tomokazu; Yui, Yuko; Miyazaki, Shota; Nakamoto, Akihiro; Namera, Akira; Inokuchi, Sadaki

2011-04-01

115

Extracting Oxygen from Lunar Simulant Using a Transparent Furnace Pulsed Fluidized Bed  

NASA Technical Reports Server (NTRS)

In the event that humans return to the moon, utilizing the local materials will be beneficial for extended stays. Rather than transporting resources, such as oxygen, from Earth, NASA is investigating methods of extracting it from lunar regolith. One promising process is hydrogen reduction. In the hydrogen reduction process, lunar regolith is heated to 1000 C in the presence of hydrogen. The iron oxide (Fe-O) bonds, found in lunar material, are broken and the hydrogen attracts the oxygen to produce water vapor [Allen et al., 1996]. FeO + H2 (right arrow) Fe +H2O. The water vapor is then captured, cleaned, and electrolyzed. The hydrogen is recycled back to the reduction process and the oxygen is stored until consumed by an end user (propulsion, life support, etc.). To obtain a good oxygen yield, the majority of lunar regolith must be exposed to the hydrogen gas and have a high rate of heat transfer from heat source to particle. This is achieved with good solids mixing via fluidization or mechanical agitation. In Generation II of the ROxygen program, the ROxygen Team at Johnson Space Center (JSC) investigated the feasibility of gas only pulsed fluidization as the only means to mix synthetic lunar regolith (simulant) at high temperatures. Fluidized beds have been used in industry to effectively process powders for decades. They consist of gas flowing upward through a bed of particles. The stirring action continuously moves the grains around to achieve uniform mixing of gas, solids, and heat [Geldart, 1986]. A transparent furnace unit was developed by Thoughventions Unlimited LLC (TvU) to aid in the qualitative observation of the fluidization behavior at high temperatures. Multipoint thermocouples and pressure sensors provided quantitative information regarding the quality of mixing. The water produced was measured using humidity sensors and captured using a NASA designed and built condenser. Once the simulant was processed, pneumatically transporting the 'hot' simulant out of the furnace was investigated.

Oryshchyn, L.; Paz, A.; Lee, K.; Reddington, M.

2010-01-01

116

Winogradsky Columns  

NSDL National Science Digital Library

This is an exercise about Winogradsky Columns with emphasis placed on the formation and properties of microbial biofilms. It includes background reference material, a field/lab exercise, and several applications. Applications include methods for sampling column layers and a description of how to measure the electro-chemical gradient that develops within the column. Scientific illustrations and images are included as visual references.

Lennox, John; State, Penn

117

Lack of behavioral effects of high-peak-power microwave pulses from an axially extracted virtual cathode oscillator  

NASA Astrophysics Data System (ADS)

The development of high-power microwave (HPM) generators capable of producing extremely high-peak-power pulses for defense, commercial, and biomedical applications (1,2) has raised concern for the safety of the personnel operating such equipment. Occupational safety standards for radiofrequency exposure are based on the average-power density of irradiation and may lack applicability in situations where peak-power density is quite high while average-power density is relatively low. A battery of behavioral experiments was conducted to evaluate possible biological effects of high-power microwave (HPM) pulses generated by the Transformer Energized Megavolt Pulsed Output (TEMPO) microwave emitter, an axially extracted Virtual Cathode Oscillator (VIRCATOR). Free space electromagnetic energy in the frequency range 2.01 to 2.57 GHz (mean frequency = 2.11 + or - 0.09 SD) was radiated by conical horn in a TM01 mode. The overall pulse width was approximately 85 ns, with maximum power densities ranging as high as 24.11 kW/cm sq. per pulse (mean peak-power density = 10.79 kW/cm sq. + or - 0.35 SEM). The results suggest that peak power is not as important as average power in causing deleterious biological effects.

Hjeresen, Dennis L.; Umbarger, Kathryn O.; Klauenberg, B. Jon; Erwin, David N.

1989-11-01

118

Indirect spectrophotometric determination of small amounts of selenium(IV) and arsenic(V) by simple extraction using flotation columns.  

PubMed

A simple, rapid and selective procedure for the indirect spectrophotometric determination of Se(IV) and As(V) has been developed. It is based on the reduction of Se(IV) to Se(0) and As(V) to As(III) with hydroiodic acid (KI + HCl). The liberated iodine, equivalent to each analyte, is quantitatively extracted with oleic acid (HOL) surfactant. The iodine-HOL system exhibits its maximum absorbance at 435 nm. The different analytical parameters affecting the extraction and determination processes have been examined. The calibration graphs were found to be linear over the ranges 5-120 and 0.25-20 ppm of Se(IV) and As(V), with lower detection limits of 2.5 and 0.15 ppm and molar absorptivities of 1 x 10(4) and 0.5 x 10(4) dm3 mol(-1) cm(-1), respectively. Sandell's sensitivity was calculated to be 0.0078 and 0.0149 microg/cm2 in the same order. The relative standard deviation for five replicate analyses of 40 ppm Se(IV) and 4 ppm As(V) were 1.0 and 0.9%, respectively. The proposed procedure in the presence of EDTA as a masking agent for foreign ions has been successfully applied to the determination of Se(IV) in a reference sample and As(V) in copper metal, in addition to their determination in spiked and polluted water samples. PMID:11990594

Mostafa, G A; Ghazy, S E

2001-10-01

119

Feature extraction and selection for defect classification of pulsed eddy current NDT  

Microsoft Academic Search

Pulsed eddy current (PEC) is a new emerging nondestructive testing (NDT) technique using a broadband pulse excitation with rich frequency information and has wide application potentials. This technique mainly uses feature points and response signal shapes for defect detection and characterization, including peak point, frequency analysis, and statistical methods such as principal component analysis (PCA). This paper introduces the application

Tianlu Chen; Gui Yun Tian; Ali Sophian; Pei Wen Que

2008-01-01

120

Extraction of pulse repetition intervals from sperm whale click trains for ocean acoustic data mining.  

PubMed

The analysis of acoustic data from the ocean is a valuable tool to study free ranging cetaceans and anthropogenic noise. Due to the typically large volume of acquired data, there is a demand for automated analysis techniques. Many cetaceans produce acoustic pulses (echolocation clicks) with a pulse repetition interval (PRI) remaining nearly constant over several pulses. Analyzing these pulse trains is challenging because they are often interleaved. This article presents an algorithm that estimates a pulse's PRI with respect to neighboring pulses. It includes a deinterleaving step that operates via a spectral dissimilarity metric. The sperm whale (SW) produces trains with PRIs between 0.5 and 2 s. As a validation, the algorithm was used for the PRI-based identification of SW click trains with data from the NEMO-ONDE observatory that contained other pulsed sounds, mainly from ship propellers. Separation of files containing SW clicks with a medium and high signal to noise ratio from files containing other pulsed sounds gave an area under the receiver operating characteristic curve value of 0.96. This study demonstrates that PRI can be used for the automated identification of SW clicks and that deinterleaving via spectral dissimilarity contributes to algorithm performance. PMID:23363108

Zaugg, Serge; van der Schaar, Mike; Houégnigan, Ludwig; André, Michel

2013-02-01

121

Development of a silica monolith modified with Fe3 O4 nano-particles in centrifugal spin column format for the extraction of phosphorylated compounds.  

PubMed

In this study, citrate-stabilised iron oxide nano-particles (?16 nm) have been immobilised on commercial silica monolithic centrifugal spin columns (MonoSpin) for the extraction of phosphorylated compounds. Two alternative strategies were adopted involving either direct electrostatic attachment to an aminated MonoSpin (single-layer method) in the first instance, or the use of a layer-by-layer method with poly(diallyldimethylammonium) chloride. Field-emission scanning electron spectroscopy and energy-dispersive X-ray spectroscopy was used for confirming notably higher coverage of nano-particles using the layer-by-layer method (2.49 ± 0.53 wt%) compared with the single-layer method (0.43 ± 0.30 wt%). The modified monolith was used for the selective separation/extraction of adenosine monophosphate, adenosine diphosphate and adenosine triphosphate with elution using a phosphate buffer. A reversed-phase liquid chromatographic assay was used for confirming that adenosine, as a non-phosphorylated control was not retained on the modified MonoSpin devices, whereas recovery of 80% for adenosine monophosphate, 86% for adenosine diphosphate and 82% for adenosine triphosphate was achieved. PMID:25376605

Alwy, Ali; Clarke, Sarah P; Brougham, Dermot F; Twamley, Brendan; Paull, Brett; White, Blánaid; Connolly, Damian

2014-11-01

122

Determination of Wastewater Compounds in Whole Water by Continuous Liquid-Liquid Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry  

USGS Publications Warehouse

A method for the determination of 69 compounds typically found in domestic and industrial wastewater is described. The method was developed in response to increasing concern over the impact of endocrine-disrupting chemicals on aquatic organisms in wastewater. This method also is useful for evaluating the effects of combined sanitary and storm-sewer overflow on the water quality of urban streams. The method focuses on the determination of compounds that are indicators of wastewater or have endocrine-disrupting potential. These compounds include the alkylphenol ethoxylate nonionic surfactants, food additives, fragrances, antioxidants, flame retardants, plasticizers, industrial solvents, disinfectants, fecal sterols, polycyclic aromatic hydrocarbons, and high-use domestic pesticides. Wastewater compounds in whole-water samples were extracted using continuous liquid-liquid extractors and methylene chloride solvent, and then determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-water samples fortified at 0.5 microgram per liter averaged 72 percent ? 8 percent relative standard deviation. The concentration of 21 compounds is always reported as estimated because method recovery was less than 60 percent, variability was greater than 25 percent relative standard deviation, or standard reference compounds were prepared from technical mixtures. Initial method detection limits averaged 0.18 microgram per liter. Samples were preserved by adding 60 grams of sodium chloride and stored at 4 degrees Celsius. The laboratory established a sample holding-time limit prior to sample extraction of 14 days from the date of collection.

Zaugg, Steven D.; Smith, Steven G.; Schroeder, Michael P.

2006-01-01

123

Continuous and pulsed ultrasound-assisted extractions of antioxidants from pomegranate peel  

Technology Transfer Automated Retrieval System (TEKTRAN)

There is a great demand for developing efficient extraction methods in order to reduce extraction time and increase the yield and activity of functional antioxidants. The yields, activities, and extraction kinetics of antioxidants from dry peel of pomegranate marc were studied using ultrasound assis...

124

Continuous and pulsed ultrasound-assisted extractions of antioxidants from pomegranate peel  

Technology Transfer Automated Retrieval System (TEKTRAN)

There is a great demand for developing efficient extraction methods in order to reduce extraction time and increase the yield and activity of functional antioxidants. The yields, activities, and extraction kinetics of antioxidants from dry peel of pomegranate marc were studied using ultrasound-assis...

125

Novel on-line column extraction apparatus coupled with binary peak focusing for high-performance liquid chromatography determination of rifampicin in human plasma: a strategy for therapeutic drug monitoring.  

PubMed

In order to develop a method that is completely suitable for the routine therapeutic drug monitoring, a sensitive and fully automated on-line column extraction apparatus in combination with high-performance liquid chromatography allowing binary peak focusing was developed and validated for the determination of rifampicin in human plasma. Rifapentine was used as an internal standard. The analytical cycle started with the injection of 100 ?L of the sample pretreated by protein precipitation in a Venusil SCX extraction column. After the elution, the analytes were transferred and concentrated in an Xtimate C18 trap column. Finally, the trapped analytes were separated by an Xtimate C18 analytical column and were analyzed by an ultraviolet detector at 336 nm. With this new strategy, continuous on-line analysis of the compounds was successfully performed. The method showed excellent performance for the analysis of rifampicin in plasma samples, including calibration curve linearity (All r were larger than 0.9996), sensitivity (lowest limit of quantification was 0.12 ?g/mL), method accuracy (within 6.6% in terms of relative error), and precision (relative standard deviations of intra- and interday precision were less than 7.8%). These results demonstrated that the simple, reliable, and automatic method based on on-line column extraction and binary peak focusing is a promising approach for therapeutic drug monitoring in complex biomatrix samples. PMID:25328044

Li, Wei; Peng, Min; Long, Minghui; Qiu, Ximin; Yang, Liping

2014-12-01

126

Trace determination of lenalidomide in plasma by non-extractive HPLC procedures with fluorescence detection after pre-column derivatization with fluorescamine  

PubMed Central

Background Lenalidomide (LND) is a new potent drug used for treatment of multiple myeloma. For its pharmacokinetic studies and therapeutic monitoring, a proper analytical method was required. Results In this study, a non extractive and simple pre-column derivatization procedures have been proposed, for the for trace determination of lenalidomide (LND) in human plasma by HPLC with fluorescence detection. Plasma samples were treated with acetonitrile for protein precipitation then treated with copper acetate to form stable complexes with the biogenic amines and mask their interference with the derivatization reaction of LND. Treated plasma samples containing LND was derivatized with fluorescamine (FLC) in aqueous media at ambient temperature. Separation of the derivatized LND was performed on Hypersil BDS C18 column (250?×?4.6?mm, 5??m particle size) using a mobile phase consisting of phosphate buffer (pH?4):methanol: tetrahydrofuran (70:10:20, v/v) at a flow rate of 1.0?mL/min. The derivatized samples were monitored at an emission wavelength of 495?nm after excitation at a wavelength of 382?nm. Under the optimum chromatographic conditions, a linear relationship with good correlation coefficient (r?=?0.9997, n?=?9) was found between the peak area and LND concentrations in the range of 2–100?ng/mL. The limits of detection and quantitation were 0.8 and 2.30?ng/mL, respectively. The intra- and inter-assay precisions were satisfactory and the accuracy of the method was proved. The recovery of LND from the spiked human plasma was 99.30?±?2.88. Conclusions The proposed method had high throughput as the analysis involved simple sample pre-treatment procedure and a relatively short run-time (< 15?min). The results demonstrated that the method would have a great value when it is applied in the therapeutic monitoring and pharmacokinetic studies for LND. PMID:23497635

2013-01-01

127

Comprehensive characterization of Annonaceous acetogenins within a complex extract by HPLC-ESI-LTQ-Orbitrap® using post-column lithium infusion.  

PubMed

Annonaceous acetogenins (AAGs) are a homogenous class of polyketides proposed as environmental neurotoxins. Previous dereplication studies of AAGs were limited by the use of low-resolution mass spectrometers. Only poor information in terms of structures was provided due to the limited fragmentation of protonated or sodium cationized species. An innovative approach, using reversed-phase high-performance liquid chromatography coupled to a hybrid linear ion trap/orbitrap mass spectrometer (LTQ-Orbitrap®), was therefore performed. Sensitivity was enhanced by post-column infusion of lithium, since AAGs have a high affinity for this cation. High level of structural information was obtained from low-energy-collision-induced dissociation fragmentation experiments of lithium-cationized AAGs ([M + Li](+) ions) as demonstrated with purified standards. The method was then applied to a total ethyl-acetate extract prepared from commercial soursop nectar (Annona muricata L.). The sensitivity, mass accuracy and specific fragmentation patterns proved to be particularly useful for characterization of the AAGs. Typical structural identification procedure and unexpected observations for specific structural types are illustrated, with major and minor compounds. PMID:23147829

Le Ven, Jessica; Schmitz-Afonso, Isabelle; Lewin, Guy; Laprévote, Olivier; Brunelle, Alain; Touboul, David; Champy, Pierre

2012-11-01

128

In vitro gastric and intestinal digestions of pulsed light-treated shrimp extracts  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pulsed ultraviolet light (PUV), a novel technology most commonly used for microbial inactivation, has recently been employed to effectively mitigate food allergens in peanuts, soybean, shrimp, and almond. Putative mechanisms for the efficacy of PUV in reducing allergen reactivity, include photother...

129

Method of fast trace microanalysis of the chiral pesticides epoxiconazole and novaluron in soil samples using off-line flow-through extraction and on-column direct large volume injection in reversed-phase high performance liquid chromatography.  

PubMed

An analytical method combining off-line flow-through extraction of a soil micro-sample (mass around 100 mg, packed into a short HPLC glass column) and direct on-column large-volume injection (LVI up to 1.00 mL) of a methanol-water soil extract onto a conventional C18 RP HPLC column enabled fast (within 3.5 minutes) trace micro-analysis of the relatively new chiral pesticides epoxiconazole (E) and novaluron (N), respectively. Linear calibration curves were evaluated from UV detection (230 nm) data in the range from 0.1 to 5 mg/kg in three most abundant Slovak agricultural soils. LOD (confidence band) at the levels 0.08-0.11 mg/kg and LOQ 0.4-0.6 mg/kg and LOD (S/N = 3) at the levels 0.007-0.018 mg/kg and LOQ (S/N = 10) 0.024-0.060 mg/kg, respectively, of dry soil were achieved. Recovery of pesticides in the overall LVI method including flow-through 130-200 mg soil micro-sample extraction was: for epoxiconazole from 74 to 85% and from 56% to 90% for novaluron with reproducibility within +/- 6% RSD. This fast (30 min) and simple method consists of just three steps which are short column filling with a solid micro-sample; flow-through liquid extraction and direct large-volume injection RP HPLC DAD analysis. The method is prepared for automation and further analysis of enantiomers of both investigated pesticides by achiral-chiral column switching techniques. PMID:18027358

Rybár, Ivan; Góra, Robert; Hutta, Milan

2007-12-01

130

Testing a prototype pulse generator for a continuous flow system and its use for E. coli inactivation and microalgae lipid extraction.  

PubMed

Among other applications, electroporation is used for the inactivation of pathogens and extraction of substances from microorganisms in liquids where large scale flow systems are used. The aim of our work was therefore to test a pulse generator that enables continuous pulsed electric field (PEF) treatment for Escherichia coli inactivation and microalgae lipid extraction. In the continuous flow PEF system, the flow rate was adjusted so that each bacterial cell received a defined number of pulses. The results of PEF flow treatment showed that the number of pulses influences E. coli inactivation to the same extent as in the previously described cuvette system, i.e., batch system. The continuous flow PEF system was also tested and evaluated for lipid extraction from microalgae Chlorella vulgaris. In control experiments, lipids were extracted via concentration of biomass, drying and cell rupture using pressure or an organic solvent. In contrast, electroporation bypasses all stages, since cells were directly ruptured in the broth and the oil that floated on the broth was skimmed off. The initial experiments showed a 50% oil yield using the electroporation flow system in comparison to extraction with organic solvent. PMID:24713586

Flisar, Karel; Meglic, Sasa Haberl; Morelj, Jernej; Golob, Janvit; Miklavcic, Damijan

2014-12-01

131

Column Chromatography  

NSDL National Science Digital Library

In this activity, learners separate the components of Gatorade using a home-made affinity column. In doing so, learners model the basic principle of affinity chromatography, a technique used to purify chemicals as well as bio-pharmaceuticals and petroleum products. This resource contains information about affinity chromatography and polarity.

Yu, Julie

2007-01-01

132

On-line coupling of sequential injection extraction with restricted-access materials and post-column derivatization for sample clean-up and determination of propranolol in human plasma.  

PubMed

The presented paper deals with a new methodology for direct determination of propranolol in human plasma. The methodology described is based on sequential injection analysis technique (SIA) coupled with solid phase extraction (SPE) column based on restricted access materials (RAM). Special RAM column containing 30 microm polymeric material-N-vinylacetamide copolymer was integrated into the sequential injection manifold. SIA-RAM system was used for selective retention of propranolol, while the plasma matrix components were eluted with two weak organic solutions to waste. Due to the acid-basic and polarity properties of propranolol molecule and principles of reversed-phase chromatography, it was possible to retain propranolol on the N-vinylacetamide copolymer sorbent (Shodex MSpak PK-2A 30 microm (2 mm x 10 mm)). Centrifuged plasma samples were aspirated into the system and loaded onto the column using acetonitrile-water (5:95, v/v), pH 11.00, adjusted by triethylamine. The analyte was retained on the column while proteins contained in the sample were removed to waste. Interfering endogenous substances complicating detection were washed out by acetonitrile-water (15:85), pH 11.00 in the next step. The extracted analyte was eluted by means of tetrahydrofuran-water (25:75), pH 11.00 to the fluorescence detector (emission filter 385 nm). The whole procedure comprising sample pre-treatment, analyte detection and column reconditioning took about 15 min. The recoveries of propranolol from undiluted plasma were in the range 96.2-97.8% for three concentration levels of analyte. The proposed SIA-RAM method has been applied for direct determination of propranolol in human plasma. PMID:17903473

Satínský, Dalibor; Serralheiro, Hugo S; Solich, Petr; Araújo, Alberto N; Montenegro, Maria C B S M

2007-09-26

133

Testing a prototype pulse generator for a continuous flow system and its use for E. coli inactivation and microalgae lipid extraction  

E-print Network

and extraction of substances from microorganisms in liquids where large scale flow systems are used. The aim system, the flow rate was adjusted so that each bacterial cell received a defined num- ber of pulses in the broth and the oil that floated on the broth was skimmed off. The initial experiments showed a 50% oil

Ljubljana, University of

134

Zenix SEC Column Manual Column Information  

E-print Network

bed density for maximum column efficiency. Zenix SEC phases are designed to ensure highest resolution1 Zenix SEC Column Manual Column Information Utilizing proprietary surface technologies and 3 m technologies allow the chemistry of thin film formation to be well controlled, which results in high column-to-column

Lebendiker, Mario

135

Determination of priority phenolic compounds in water and industrial effluents by polymeric liquid-solid extraction cartridges using automated sample preparation with extraction columns and liquid chromatography use of liquid-solid extraction cartridges for stabilization of phenols  

Microsoft Academic Search

Fourteen phenolic compounds: catechol, phenol, 4-nitrophenol, 4-methylphenol, 2,4-dinitrophenol, 2-nitrophenol, 2-chlorophenol, 4-chlorophenol, 3-chlorophenol, 4-chloro-3-methylphenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 2,4,6,-trichlorophenol and pentachlorophenol, which are included in the priority pollutants list of the US Environmental Protection Agency and in the European Union list 76\\/464, were determined in water by liquid-solid extraction (LSE) followed by liquid chromatography with UV detection (LC-UV). Three different polymeric sorbents were

M. Castillo; D. Puig; D. Barcelo´

1997-01-01

136

Virus movement in soil columns flooded with secondary sewage effluent.  

PubMed

Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles. PMID:185960

Lance, J C; Gerba, C P; Melnick, J L

1976-10-01

137

Virus movement in soil columns flooded with secondary sewage effluent.  

PubMed Central

Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles. PMID:185960

Lance, J C; Gerba, C P; Melnick, J L

1976-01-01

138

Polytetrafluorethylene film-based liquid-three phase micro extraction coupled with differential pulse voltammetry for the determination of atorvastatin calcium.  

PubMed

In this paper, we describe a new combination method based on polytetrafluorethylene (PTFE) film-based liquid three-phase micro extraction coupled with differential pulse voltammetry (DPV) for the micro extraction and quantification of atorvastatin calcium (ATC) at the ultra-trace level. Different factors affecting the liquid-three phases micro extraction of atorvastatin calcium, including organic solvent, pH of the donor and acceptor phases, concentration of salt, extraction time, stirring rate and electrochemical factors, were investigated, and the optimal extraction conditions were established. The final stable signal was achieved after a 50 min extraction time, which was used for analytical applications. An enrichment factor of 21 was achieved, and the relative standard deviation (RSD) of the method was 4.5% (n = 4). Differential pulse voltammetry exhibited two wide linear dynamic ranges of 20.0-1000.0 pmol L(-1) and 0.001-11.0 µmol L(-1) of ATC. The detection limit was found to be 8.1 pmol L(-1) ATC. Finally, the proposed method was used as a new combination method for the determination of atorvastatin calcium in real samples, such as human urine and plasma. PMID:23474719

Ensafi, Ali A; Khoddami, Elaheh; Rezaei, Behzad

2013-01-01

139

Methods of analysis by the U. S. Geological Survey National Water Quality Laboratory - determination of organonitrogen herbicides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry with selected-ion monitoring  

USGS Publications Warehouse

A method for the isolation of organonitrogen herbicides from natural water samples using solid-phase extraction and analysis by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase extraction cartridges containing octadecyl-bonded porous silica to remove the herbicides. The cartridges are dried using carbon dioxide, and adsorbed herbicides are removed from the cartridges by elution with 1.8 milliliters of hexaneisopropanol (3:1). Extracts of the eluants are analyzed by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of at least three characteristic ions. The method detection limits are dependent on sample matrix and each particular herbicide. The method detection limits, based on a 100-milliliter sample size, range from 0.02 to 0.25 microgram per liter. Recoveries averaged 80 to 115 percent for the 23 herbicides and 2 metabolites in 1 reagent-water and 2 natural-water samples fortified at levels of 0.2 and 2.0 micrograms per liter.

Sandstrom, Mark W.; Wydoski, Duane S.; Schroeder, Michael P.; Zamboni, Jana L.; Foreman, William T.

1992-01-01

140

Recent advances in column switching sample preparation in bioanalysis.  

PubMed

Column switching techniques, using two or more stationary phase columns, are useful for trace enrichment and online automated sample preparation. Target fractions from the first column are transferred online to a second column with different properties for further separation. Column switching techniques can be used to determine the analytes in a complex matrix by direct sample injection or by simple sample treatment. Online column switching sample preparation is usually performed in combination with HPLC or capillary electrophoresis. SPE or turbulent flow chromatography using a cartridge column and in-tube solid-phase microextraction using a capillary column have been developed for convenient column switching sample preparation. Furthermore, various micro-/nano-sample preparation devices using new polymer-coating materials have been developed to improve extraction efficiency. This review describes current developments and future trends in novel column switching sample preparation in bioanalysis, focusing on innovative column switching techniques using new extraction devices and materials. PMID:22512799

Kataoka, Hiroyuki; Saito, Keita

2012-04-01

141

ALTERNATIVES TO METHANOL WATER ELUTION OF SOLID-PHASE EXTRACTION COLUMNS FOR THE FRACTIONATION OF HIGH LOG KOW ORGANIC COMPOUNDS IN AQUEOUS ENVIRONMENTAL SAMPLES  

EPA Science Inventory

A toxicity-directed method for fractionating non-polar organic toxicants using solid-phase extraction (SPE) is described in phase II of EPA's "Methods for Aquatic Toxicity Evaluations". his method has been used very successfully to extract and fractionate acutely and chronically ...

142

Sensitive high-performance anion-exchange chromatographic determination of paeoniflorin and albiflorin by pulsed amperometric detection after solid-phase extraction  

Microsoft Academic Search

We developed a method to simultaneously determine paeoniflorin and albiflorin levels using high-performance anion-exchange liquid chromatography with pulsed amperometric detection (HPAEC-PAD). The main principle of our method includes solid-phase extraction step using Amberlite XAD-2 sorbent to remove sugars and to selectively determine glycosides by PAD. Under these conditions, the linear dynamic range was 0.01–100?g\\/mL, and the albiflorin and paeoniflorin detection

Hee-Jung Sim; Ji-Seon Jeong; Ha-Jeong Kwon; Yong-Moon Lee; Seon-Pyo Hong

2010-01-01

143

Flow injection solid-phase extraction using multi-walled carbon nanotubes packed micro-column for the determination of polycyclic aromatic hydrocarbons in water by gas chromatography-mass spectrometry.  

PubMed

A flow injection solid-phase extraction preconcentration system using a multi-walled carbon nanotubes (MWCNTs) packed micro-column was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in water by gas chromatography-mass spectrometry (GC-MS). The preconcentration of PAHs on the MWCNTs was carried out based on the adsorption retention of analytes by on-line introducing the sample into the micro-column system. Methanol was introduced to elute the retained analytes for GC-MS analysis using selected ion monitoring (SIM) mode. Important influence factors were studied in detail, such as sample acidity, sample flow rate, eluent flow rate and volume, dimensions of MWCNTs and amounts of packing material. Limits of detection of 16 PAHs for an extraction of 50 mL water sample were in the range of 0.001-0.15 microg L(-1), and the precisions (RSD) were in the range of 4-14%. The optimized method was successfully applied to the determination of 16 PAHs in surface waters, with recoveries in the range of 72-93% for real spiked sample. PMID:20236647

Wu, Hong; Wang, Xuecui; Liu, Bing; Lu, Jie; Du, Baixiang; Zhang, Luxin; Ji, Jingjing; Yue, Qiaoyu; Han, Baoping

2010-04-23

144

Millisecond duration pulses for flow-through electro-induced protein extraction from E. coli and associated eradication.  

PubMed

Pulsed electric fields are used to induce membrane permeabilization on cells. In the case of species with cell wall (yeasts, microalgae), it was previously shown that when the pulse duration was several ms long, this resulted in a cytoplasmic soluble protein slow leakage. In this work, we show that a similar consequence can be obtained with different strains of E. coli. Experimental evidences of a resulting wall alteration are described. Pre-industrial flow process pilots are used. As the membrane electropermeabilization can be irreversible by applying a proper choice of the pulse parameters, this approach is used for bacterial inactivation in flow process. It is observed that sub-millisecond pulse trains are more cost effective than longer ones. PMID:25183448

Coustets, M; Ganeva, V; Galutzov, B; Teissie, J

2014-08-23

145

Automated sample preparation with extraction columns followed by liquid chromatography-ionspray mass spectrometry interferences, determination and degradation of polar organophosphorus pesticides in water samples  

Microsoft Academic Search

The determination of polar and\\/or thermally labile organophosphorus pesticides trichlorfon, dichlorvos, dimethoate, oxydemeton-methyl, mevinphos (cis and trans), demeton-S-methyl, fenamiphos, fenitrothion, fenthion and diazinon in water samples was investigated using solid-phase extraction followed by liquid chromatography-ionspray mass spectrometry (LC-ISP-MS). Pesticides were spiked at 0.2 ?g\\/l in ground water samples and 200 ml were preconcentrated by using an ASPEC XL system. To

C Molina; P Grasso; E Benfenati; D Barceló

1996-01-01

146

Stability of sulfonated derivatives of benzene and naphthalene on disposable solid-phase extraction pre-columns and in an aqueous matrix.  

PubMed

The stability of 14 sulfonated benzene and naphthalene compounds was investigated using polymeric solid-phase extraction cartridges, based on the styrene-divinylbenzene polymer Isolute ENV+. Several different storage conditions were tested to carry out the stability study in polymeric cartridges, which included storage at room temperature, at 4 degrees C and at -20 degrees C, during a period of up to 3 months. An additional stability study was carried out, not with the polymeric solid matrix, but in an aqueous matrix. This study was performed storing the samples at 4 degrees C, during 2 months under three different conditions: acidifying the water sample to pH 2.5-3 with sulfuric acid, adding 1% of formaldehyde (additive used in waste water analyses), and storing the water sample at 4 degrees C without any additives. The extraction of the SPE process is analyzed by ion-pair chromatography-electrospray mass spectrometry, in the negative ion mode. This study showed that the stability of polar aromatic sulfonic acids on disposable polymeric cartridges and in the water matrix is related to temperature and pH, respectively. Target aromatic sulfonated compounds stored in polymeric solid-phase extraction cartridges, are more stable at lower temperatures. The target analytes showed also good stability when stored in water at acidic pH. From the different analytes studied, substituted naphthalenesulfonates suffered more degradation than mononaphthalenesulfonates or benzenesulfonates under the experimental conditions of this work. PMID:10985554

Alonso, M C; Barceló, D

2000-08-11

147

Determination of lead by on-line solid phase extraction using a PTFE micro-column and flame atomic absorption spectrometry.  

PubMed

A rapid and sensitive time-based flow injection (FI) method for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS), using polytetrafluoroethylene (PTFE) turnings as packing material in a micro-column, has been developed. The sample was mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the non-charged Pb(II)-PDC complex was absorbed quantitatively on the hydrophobic PTFE material, at a pH range 1.4-3.2. The preconcentrated complex was effectively eluted with isobutyl methyl ketone (IBMK) and introduced into the nebulizer-burner system. A nested coil (NC) is proposed for parking the eluate temporarily, in order to enable different elution and nebulization flow rates. With 180 s preconcentration time the sample frequency was 15 h(-1), and the enhancement factor was 330 at 13.0 ml min(-1) sample flow rate. The detection limit was c(L)=0.8 mug l(-1), the relative standard deviation (R.S.D.) 2.6% at the 30 mug l(-1) level and the calibration curve was linear over the concentration range 1.6-100 mug l(-1). The proposed method was evaluated by analyzing certified reference materials of water, sediments and fish tissue. Finally, it was applied successfully to the analysis of various environmental samples. PMID:18968696

Zachariadis, George A; Anthemidis, Aristidis N; Bettas, Peter G; Stratis, John A

2002-07-01

148

Analysis of flavonol aglycones and terpenelactones in Ginkgo biloba extract: A comparison of high-performance thin-layer chromatography and column high-performance liquid chromatography.  

PubMed

Advancements in automated high-performance thin-layer chromatography (HPTLC) have made it feasible to assess its use for the quantitative analysis of marker compounds in botanical preparations. We report here the findings of method comparisons for the terpenelactones and flavonol aglycones by column high-performance liquid chromatography (HPLC) with evaporative light scattering and UV detection, and HPTLC with a scanning densitometer. For the HPTLC assay of terpenelactones, total bilobalide, ginkgolide A, and ginkgolide B consistently achieved <70% of the total determined using HPLC, regardless of variations to postchromatographic derivatization time and temperature. Accuracy testing showed the possibility of a matrix interference. In contrast, a good relationship (95%) was determined between HPTLC and HPLC for determination of total flavonol glycosides (calculated from combined quercetin, kaempferol, and isorhamnetin) from an acid-hydrolyzed Ginkgo biloba L. (GBE) sample. The HPTLC flavonol aglycone method also performed well in terms of accuracy (overall average of 96% recovery for the 3 aglycones) and consecutive plate repeatability (overall percent relative standard deviation of 4.4). It is demonstrated that HPTLC can be a time-saving complement to HPLC for routine analysis of the flavonol glycosides in GBE. PMID:17955963

Gray, Dean E; Messer, Dale; Porter, Andrew; Hefner, Brian; Logan, Dama; Harris, Roger K; Clark, Alice P; Algaier, Joseph A; Overstreet, J Diane; Smith, Cynthia S

2007-01-01

149

Methods of analysis and quality-assurance practices of the U.S. Geological Survey organic laboratory, Sacramento, California; determination of pesticides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry  

USGS Publications Warehouse

Analytical method and quality-assurance practices were developed for a study of the fate and transport of pesticides in the Sacramento-San Joaquin Delta and the Sacramento and San Joaquin River. Water samples were filtered to remove suspended parti- culate matter and pumped through C-8 solid-phase extraction cartridges to extract the pesticides. The cartridges were dried with carbon dioxide, and the pesticides were eluted with three 2-milliliter aliquots of hexane:diethyl ether (1:1). The eluants were analyzed using capillary-column gas chromatography/mass spectrometry in full-scan mode. Method detection limits for analytes determined per 1,500-milliliter samples ranged from 0.006 to 0.047 microgram per liter. Recoveries ranged from 47 to 89 percent for 12 pesticides in organic-free, Sacramento River and San Joaquin River water samples fortified at 0.05 and 0.26 microgram per liter. The method was modified to improve the pesticide recovery by reducing the sample volume to 1,000 milliliters. Internal standards were added to improve quantitative precision and accuracy. The analysis also was expanded to include a total of 21 pesticides. The method detection limits for 1,000-milliliter samples ranged from 0.022 to 0.129 microgram per liter. Recoveries ranged from 38 to 128 percent for 21 pesticides in organic-free, Sacramento River and San Joaquin River water samples fortified at 0.10 and 0.75 microgram per liter.

Crepeau, Kathryn L.; Domagalski, Joseph L.; Kuivila, Kathryn M.

1994-01-01

150

Numerical simulations of output pulse extraction from a high-power microwave compressor with a plasma switch  

SciTech Connect

Numerical simulations of the process of electromagnetic energy release from a high-power microwave pulse compressor comprising a gas-filled cavity and interference switch were carried out. A microwave plasma discharge in a rectangular waveguide H-plane tee was modeled with the use of the fully electromagnetic particle-in-cell code MAGIC. The gas ionization, plasma evolution, and interaction with RF fields accumulated within the compressor were simulated using different approaches provided by the MAGIC code: particle-in-cell approach accounting for electron-neutral collisions, gas conductivity model based on the concept of mobility, and hybrid modeling. The dependences of the microwave output pulse peak power and waveform on parameters that can be controlled in experiments, such as an external ionization rate, RF field amplitude, and background gas pressure, were investigated.

Shlapakovski, Anatoli; Beilin, Leonid; Bliokh, Yuri; Donskoy, Moshe; Krasik, Yakov E. [Physics Department, Technion, Haifa 32000 (Israel); Hadas, Yoav [Department of Applied Physics, Rafael, PO Box 2250, Haifa 31021 (Israel); Schamiloglu, Edl [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2014-05-07

151

Numerical simulations of output pulse extraction from a high-power microwave compressor with a plasma switch  

NASA Astrophysics Data System (ADS)

Numerical simulations of the process of electromagnetic energy release from a high-power microwave pulse compressor comprising a gas-filled cavity and interference switch were carried out. A microwave plasma discharge in a rectangular waveguide H-plane tee was modeled with the use of the fully electromagnetic particle-in-cell code MAGIC. The gas ionization, plasma evolution, and interaction with RF fields accumulated within the compressor were simulated using different approaches provided by the MAGIC code: particle-in-cell approach accounting for electron-neutral collisions, gas conductivity model based on the concept of mobility, and hybrid modeling. The dependences of the microwave output pulse peak power and waveform on parameters that can be controlled in experiments, such as an external ionization rate, RF field amplitude, and background gas pressure, were investigated.

Shlapakovski, Anatoli; Beilin, Leonid; Bliokh, Yuri; Donskoy, Moshe; Hadas, Yoav; Schamiloglu, Edl; Krasik, Yakov E.

2014-05-01

152

Assessment of the quantitative determination of paralytic shellfish poisoning toxins by pre-column derivatization and elimination of interfering compounds by solid-phase extraction.  

PubMed

Monitoring programmes for paralytic shellfish poisoning toxins in bivalve molluscs still rely heavily on the use of mouse bioassays (MBA) for consumer protection. A high-performance liquid chromatography (HPLC) methodology (Lawrence method) was implemented in 1996 in the Portuguese monitoring programme as a complementary means of analysis. Comparison between MBA and HPLC was done at the time only by a qualitative approach due to the scarce number of positive samples tested. More quantitative data were obtained recently when studying toxin profiles in Moroccan shellfish, and the correlation found between these two methodologies is reported here for the first time. Two different matrices were studied: blue mussel and the giant cockle Acanthocardia tuberculatum. A good linear correlation was obtained for both matrices. However, a second-degree polynomial best fitted the data at both low and high extremes of toxicity. According to the HPLC quantitative results, 13% of false-negatives could be obtained by MBA due to an underestimation of toxicity near the limit of detection of the MBA. Difficulties on relying solely on HPLC for consumer protection have been aroused with uncommon matrices, such as imported clams or crustaceans, due to the presence of high concentrations of interfering compounds. The solid-phase extraction step of the Lawrence method was implemented to eliminate an unknown compound that could be mistaken for saxitoxin, and an 80% reduction of another common unknown compound eluting close to decarbamoylsaxitoxin. The implementation of the HPLC methodology achieved so far allows a high degree of consumer protection without the need to resource to animal sacrifice. PMID:16192070

Vale, P; Taleb, H

2005-09-01

153

Five points on columns  

E-print Network

Column,” like “gene,” has both conceptual and linguistic shortcomings. The simple question “what is a column” is not easy to answer and the word itself is not easy to replace. In the present article, I have selected five ...

Rockland, Kathleen

154

Liquid chromatographic extraction medium  

DOEpatents

A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

Horwitz, E. Philip (Naperville, IL); Dietz, Mark L. (Evanston, IL)

1994-01-01

155

Liquid chromatographic extraction medium  

DOEpatents

A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

Horwitz, E.P.; Dietz, M.L.

1994-09-13

156

Liquid-Liquid Extraction Equipment  

SciTech Connect

Solvent extraction processing has demonstrated the ability to achieve high decontamination factors for uranium and plutonium while operating at high throughputs. Historical application of solvent extraction contacting equipment implies that for the HA cycle (primary separation of uranium and plutonium from fission products) the equipment of choice is pulse columns. This is likely due to relatively short residence times (as compared to mixer-settlers) and the ability of the columns to tolerate solids in the feed. Savannah River successfully operated the F-Canyon with centrifugal contactors in the HA cycle (which have shorter residence times than columns). All three contactors have been successfully deployed in uranium and plutonium purification cycles. Over the past 20 years, there has been significant development of centrifugal contactor designs and they have become very common for research and development applications. New reprocessing plants are being planned in Russia and China and the United States has done preliminary design studies on future reprocessing plants. The choice of contactors for all of these facilities is yet to be determined.

Jack D. Law; Terry A. Todd

2008-12-01

157

Column Liquid Chromatography.  

ERIC Educational Resources Information Center

Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

Majors, Ronald E.; And Others

1984-01-01

158

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of organophosphate pesticides in whole water by continuous liquid-liquid extraction and capillary-column gas chromatography with flame photometric detection  

USGS Publications Warehouse

A method for the isolation of 20 parent organophosphate pesticides and 5 organophosphate pesticide degradates from natural-water samples is described. Compounds are extracted from water samples with methylene chloride using a continuous liquid-liquid extractor for 6 hours. The solvent is evaporated using heat and a flow of nitrogen to a volume of 1 milliliter and solvent exchanged to ethyl acetate. Extracted compounds are determined by capillary-column gas chromatography with flame photometric detection. Single-operator derived method detection limits in three water-matrix samples ranged from 0.003 to 0.009 microgram per liter. Method performance was validated by spiking all compounds in three different matrices at three different concentrations. Eight replicates were analyzed at each concentration in each matrix. Mean recoveries of most method compounds spiked in surface-water samples ranged from 54 to 137 percent and those in ground-water samples ranged from 40 to 109 percent for all pesticides. Recoveries in reagent-water samples ranged from 42 to 104 percent for all pesticides. The only exception was O-ethyl-O-methyl-S-propylphosphorothioate, which had variable recovery in all three matrices ranging from 27 to 79 percent. As a result, the detected concentration of O-ethyl-O-methyl-S-propylphosphorothioate in samples is reported in this method with an estimated remark code. Based on the performance issue, two more compounds, disulfoton and ethion monoxon, also will be reported in this method with an estimated remark code. Estimated-value compounds, which are ?E-coded? in the data base, do not meet the performance criteria for unqualified quantification, but are retained in the method because the compounds are important owing to high use or potential environmental effects and because analytical performance has been consistent and reproducible.

Jha, Virendra K.; Wydoski, Duane S.

2003-01-01

159

Methods of Analysis by the U.S. Geological Survey National Water Quality Laboratory - Determination of Wastewater Compounds by Polystyrene-Divinylbenzene Solid-Phase Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry  

USGS Publications Warehouse

A method for the determination of 67 compounds typically found in domestic and industrial wastewater is described. The method was developed in response to increasing concern over the impact of endocrine-disrupting chemicals in wastewater on aquatic organisms. This method also may be useful for evaluating the impact of combined sanitary and storm-sewer overflow on the water quality of urban streams. The method focuses on the determination of compounds that are an indicator of wastewater or that have been chosen on the basis of their endocrine-disrupting potential or toxicity. These compounds include the alkylphenol ethoxylate nonionic surfactants and their degradates, food additives, fragrances, antioxidants, flame retardants, plasticizers, industrial solvents, disinfectants, fecal sterols, polycyclicaromatic hydrocarbons, and high-use domestic pesticides. Water samples are filtered to remove suspended particulate matter and then are extracted by vacuum through disposable solid-phase cartridges that contain polystyrene-divinylbenzene resin. Cartridges are dried with nitrogen gas, and then sorbed compounds are eluted with dichloromethane-diethyl ether (4:1) and determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-water samples fortified at 4 micrograms per liter averaged 74 percent ? 7 percent relative standard deviation for all method compounds. Initial method detection limits for single-component compounds (excluding hormones and sterols) averaged 0.15 microgram per liter. Samples are preserved by filtration, the addition of 60 grams NaCl, and storage at 4 degrees Celsius. The laboratory has established a sample-holding time (prior to sample extraction) of 14 days from the date of sample collection until a statistically accepted method can be used to determine the effectiveness of these sample-preservation procedures.

Zaugg, Steven D.; Smith, Steven G.; Schroeder, Michael P.; Barber, Larry B.; Burkhardt, Mark R.

2002-01-01

160

Mesoporous titanium dioxide as a novel solid-phase extraction material for flow injection micro-column preconcentration on-line coupled with ICP-OES determination of trace metals in environmental samples.  

PubMed

Mesoporous titanium dioxide as a novel solid-phase extraction material for flow injection micro-column preconcentration on-line coupled with ICP-OES determination of trace metals (Co, Cd, Cr, Cu, Mn, Ni, V, Ce, Dy, Eu, La and Yb) in environmental samples was described. Possessing a high adsorption capacity towards the metal ions, mesoporous titanium dioxide has found to be of great potential as an adsorbent for the preconcentration of trace metal ions in samples with complicated matrix. The experimental parameters including pH, sample flow rate, volume, elution and interfering ions on the recovery of the target analytes were investigated, and the optimal experimental conditions were established. Under the optimized operating conditions, a preconcentration time of 90s and elution time of 18s with enrichment factor of 10 and sampling frequency of 20h(-1) were obtained. The detection limits of this method for the target elements were between 0.03 and 0.36mugL(-1), and the relative standard deviations (R.S.D.s) were found to be less than 6.0% (n=7, c=5ngmL(-1)). The proposed method was validated using a certified reference material, and has been successfully applied for the determination of the afore mentioned trace metals in natural water samples and coal fly ash with satisfactory results. PMID:19073028

Huang, Chaozhang; Jiang, Zucheng; Hu, Bin

2007-09-15

161

Speciation analysis of organotin compounds in human urine by headspace solid-phase micro-extraction and gas chromatography with pulsed flame photometric detection.  

PubMed

A new headspace solid-phase micro-extraction (HS-SPME) method followed by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis has been developed for the simultaneous determination of 11 organotin compounds, including methyl-, butyl-, phenyl- and octyltin derivates, in human urine. The methodology has been validated by the analysis of urine samples fortified with all analytes at different concentration levels, and recovery rates above 87% and relative precisions between 2% and 7% were obtained. Additionally, an experimental-design approach has been used to model the storage stability of organotin compounds in human urine, demonstrating that organotins are highly degraded in this medium, although their stability is satisfactory during the first 4 days of storage at 4 °C and pH=4. Finally, this methodology was applied to urine samples collected from harbor workers exposed to antifouling paints; methyl- and butyltins were detected, confirming human exposure in this type of work environment. PMID:24840433

Valenzuela, Aníbal; Lespes, Gaëtane; Quiroz, Waldo; Aguilar, Luis F; Bravo, Manuel A

2014-07-01

162

Inelastic column behavior  

NASA Technical Reports Server (NTRS)

The significant findings of a theoretical study of column behavior in the plastic stress range are presented. When the behavior of a straight column is regarded as the limiting behavior of an imperfect column as the initial imperfection (lack of straightness) approaches zero, the departure from the straight configuration occurs at the tangent-modulus load. Without such a concept of the behavior of a straight column, one is led to the unrealistic conclusion that lateral deflection of the column can begin at any load between the tangent-modulus value and the Euler load, based on the original elastic modulus. A family of curves showing load against lateral deflection is presented for idealized h-section columns of various lengths and of various materials that have a systematic variation of their stress-strain curves.

Duberg, John E; Wilder, Thomas W , III

1952-01-01

163

Non-chromatographic determination of ultratraces of V(V) and V(IV) based on a double column solid phase extraction flow injection system coupled to electrothermal atomic absorption spectrometry.  

PubMed

In this work, a non-chromatographic procedure for the on-line determination of ultratraces of V(V) and V(IV) is presented. The method involves a solid phase extraction-flow injection system coupled to electrothermal atomic absorption spectrometry (SPE-FI-ETAAS). The system holds two microcolumns (MC) set in parallel and filled with lab-made mesoporous silica functionalized with 3-aminopropyltriethoxy silane (APS) and mesoporous silica MCM-41, respectively. The pre-concentration of V(V) is performed by sorption onto the first MC (C1) filled with APS at pH 3, whilst that of V(IV) is performed by sorption onto the second column (C2) filled with mesoporous silica MCM-41 at pH 5. Aqueous samples containing both analytes are loaded and, after pre-concentration (pre-concentration factor PCF=10, sorption flow rate=1 mL min(-1), sorption time=10 min), they are eluted in separate vessels with hydroxylammonium chloride (HC) 0.1 mol L(-1) in HCl 0.5 mol L(-1) (elution volume=1 mL, elution flow rate=0.5 mL min(-1)). Afterwards, both analytes are determined through ETAAS with graphite furnace. Under optimized conditions, the main analytical figures of merit for V(V) and V(IV) are, respectively: detection limits (3s): 0.5 and 0.6 microg L(-1), linear range: 2-100 microg L(-1) (both analytes), sensitivity: 0.015 and 0.013 microg(-1)L and sample throughput: 6h(-1) (both analytes). Recoveries of both species were assayed in different water samples. Validation was performed through certified reference materials for ultratraces of total vanadium in river water. PMID:19576468

Kim, Manuela Leticia; Tudino, Mabel Beatríz

2009-08-15

164

Determination of arsenic(III) by flow injection solid phase extraction coupled with on-line hydride generation atomic absorption spectrometry using a PTFE turnings-packed micro-column.  

PubMed

A novel flow injection (FI) solid phase extraction method for the determination of arsenic(III) at trace levels was developed, using on-line hydride generation atomic absorption spectrometry (HG-AAS). Selective determination of As(III) was achieved by on-line formation and retention of the pyrrolidine dithiocarbamate arsenic complex As(III)-PDC on the PTFE turnings which are packed in the preconcentration micro-column. The retained complex was eluted by 2 ml 2 mol l(-1) HCl and subsequently introduced on-line into the integrated reaction chamber/gas-liquid separator (RC-GLS). A 1.5% (m/v) NaBH4 solution was used for arsine generation, while a gas stream of N2 was employed for flash release and transportation towards the atomic absorption flow through cell (AAC) for atomization and measurement. The excellent performance of PTFE turnings as sorbent material and the compact design of the RC-GLS result to high sensitivity, selectivity and sampling frequency. For 60s preconcentration time and sample consumption 10.4 ml a sampling frequency of 25 h(-1) and a detection limit of c(L)=0.02 microg l(-1) were obtained. The repeatability, expressed as relative standard deviation (R.S.D.), at 1.0 microg l(-1) As(III), was s(r)=2.8%. The proposed method was successfully applied to the selective determination of As(III) in natural waters and total arsenic determination in certified reference material. PMID:17723554

Anthemidis, Aristidis N; Martavaltzoglou, Evdoxia K

2006-07-28

165

Zenix-C SEC Column User Manual Column Information  

E-print Network

uniform and stable packing bed density for maximum column efficiency. Zenix-C SEC phases are designed1 Zenix-C SEC Column User Manual Column Information Utilizing proprietary surface technologies in high column-to-column reproducibility. The nature of the chemical bonding and the maximum bonding

Lebendiker, Mario

166

Nuclear reactor control column  

DOEpatents

The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest cross-sectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor.

Bachovchin, Dennis M. (Plum Borough, PA)

1982-01-01

167

Figure 2. Highly effective enrichment of phosphorylated proteins. A Phosphoprotein Affinity Column was loaded with ~3 mg of total protein from HEK 293 cells. The extract (Lanes 1), flowthrough (Lanes  

E-print Network

Extraction/ Loading Buffer to the cell or tissue pellet to extract total cellular protein, loading Extraction/Loading Buffer to cell pellet Wash and elute Phosphorylated proteins Phosphoprotein Affinity was loaded with ~3 mg of total protein from HEK 293 cells. The extract (Lanes 1), flowthrough (Lanes 2), wash

Lebendiker, Mario

168

Modeling of rotating disc contactor (RDC) column  

NASA Astrophysics Data System (ADS)

Liquid-liquid extraction is one of the most important separation processes. Different kinds of liquid-liquid extractor such as Rotating Disc Contactor (RDC) Column being used in industries. The study of liquid-liquid extraction in an RDC column has become a very important subject to be discussed not just among chemical engineers but mathematician as well. In this research, the modeling of small diameter RDC column using the chemical system involving cumene/isobutryric asid/water are analyzed by the method of Artificial Neural Network (ANN). In the previous research, we begin the process of analyzed the data using methods of design of the experiments (DOE) to identify which factor and their interaction factor are significant and to determine the percentage of contribution of the variance for each factor. From the result obtained, we continue the research by discussed the development and validation of an artificial neural network model in estimating the concentration of continuous and concentration of dispersed outlet for an RDC column. It is expected that an efficient and reliable model will be formed to predict RDC column performance as an alternative to speed up the simulation process.

Ismail, Wan Nurul Aiffah; Zakaria, Siti Aisyah; Noor, Nor Fashihah Mohd; Sulong, Ibrahim; Arshad, Khairil Anuar

2014-12-01

169

Five Points on Columns  

PubMed Central

Column,” like “gene,” has both conceptual and linguistic shortcomings. The simple question “what is a column” is not easy to answer and the word itself is not easy to replace. In the present article, I have selected five points, in no way comprehensive or canonical, but which may nevertheless serve as a prompt and aid for further discussions and re-evaluation. These are: that anatomical columns are not solid structures, that they are part of locally interdigitating systems, that any delimited column also participates in a widely distributed network, that columns are not an obligatory cortical feature, and that columns (as “modules”) occur widely in the brain in non-cortical structures. I focus on the larger scale macrocolumns, mainly from an anatomical perspective. My position is that cortical organization is inherently dynamic and likely to incorporate multiple processing styles. One can speculate that the distributed mappings within areas like piriform cortex may resemble at least one mode of neocortical processing strategy. PMID:20589097

Rockland, Kathleen S.

2010-01-01

170

OPTIMIZED DETERMINATION OF TRACE JET FUEL VOLATILE ORGANIC COMPOUNDS IN HUMAN BLOOD USING IN-FIELD LIQUID-LIQUID EXTRACTION WITH SUBSEQUENT LABORATORY GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS AND ON-COLUMN LARGE VOLUME INJECTION  

EPA Science Inventory

A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing te...

171

Eruption column physics  

SciTech Connect

In this paper the author focuses on the fluid dynamics of large-scale eruption columns. The dynamics of these columns are rooted in multiphase flow phenomena, so a major part of the paper sets up a foundation on that topic that allows one to quickly assess the inherent assumptions made in various theoretical and experimental approaches. The first part is centered on a set of complex differential equations that describe eruption columns, but the focus is on a general understanding of important physical processes rather than on the mathematics. The author discusses briefly the relative merits and weaknesses of different approaches, emphasizing that the largest advances in understanding are made by combining them. He then focuses on dynamics of steady eruption columns and then on transient phenomena. Finally he briefly reviews the effects of varying behavior of the ambient medium through which an eruption column moves. These final sections will emphasize concepts and a qualitative understanding of eruption dynamics. This paper relies on principles of continuum mechanics and transport processes but does not go into detail on the development of those principles. 36 refs., 36 figs., 3 tabs.

Valentine, G.A.

1997-03-01

172

Columns in Clay  

ERIC Educational Resources Information Center

This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

Leenhouts, Robin

2010-01-01

173

Determination of parabens and endocrine-disrupting alkylphenols in soil by gas chromatography-mass spectrometry following matrix solid-phase dispersion or in-column microwave-assisted extraction: a comparative study.  

PubMed

Two rapid methods were evaluated for the simultaneous extraction of seven parabens and two alkylphenols from soil based on matrix solid-phase dispersion (MSPD) and microwave-assisted extraction (MAE). Soil extracts were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide and analyzed by gas chromatography with mass spectrometry. Extraction and clean-up of samples were carried out by both methods in a single step. A glass sample holder, inside the microwave cell, was used in MAE to allow the simultaneous extraction and clean-up of samples and shorten the MAE procedure. The detection limits achieved by MSPD were lower than those obtained by MAE because the presence of matrix interferences increased with this extraction method. The extraction yields obtained by MSPD and MAE for three different types of soils were compared. Both procedures showed good recoveries and sensitivity for the determination of parabens and alkylphenols in two of the soils assayed, however, only MSPD yielded good recoveries with the other soil. Finally, MSPD was applied to the analysis of soils collected in different sites of Spain. In most of the samples analyzed, methylparaben and butylparaben were detected at levels ranging from 1.21 to 8.04 ng g(-1) dry weight and 0.48 to 1.02 ng g(-1) dry weight, respectively. PMID:21792551

Pérez, R A; Albero, B; Miguel, E; Sánchez-Brunete, C

2012-03-01

174

Simulation of microbial transport and carbon tetrachloride biodegradation in intermittently-fed aquifer columns  

E-print Network

Simulation of microbial transport and carbon tetrachloride biodegradation in intermittently; published 10 April 2002. [1] This paper evaluates the microbial transport and degradation processes associated with carbon tetrachloride (CT) biodegradation in laboratory aquifer columns operated with a pulsed

175

Assessment of pulse rate variability by the method of pulse frequency demodulation  

Microsoft Academic Search

BACKGROUND: Due to its easy applicability, pulse wave has been proposed as a surrogate of electrocardiogram (ECG) for the analysis of heart rate variability (HRV). However, its smoother waveform precludes accurate measurement of pulse-to-pulse interval by fiducial-point algorithms. Here we report a pulse frequency demodulation (PFDM) technique as a method for extracting instantaneous pulse rate function directly from pulse wave

Junichiro Hayano; Allan Kardec Barros; Atsunori Kamiya; Nobuyuki Ohte; Fumihiko Yasuma

2005-01-01

176

Method of analysis and quality-assurance practices for determination of pesticides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry at the U.S. Geological Survey California District Organic Chemistry Laboratory, 1996-99  

USGS Publications Warehouse

A method of analysis and quality-assurance practices were developed to study the fate and transport of pesticides in the San Francisco Bay-Estuary by the U.S. Geological Survey. Water samples were filtered to remove suspended-particulate matter and pumped through C-8 solid-phase extraction cartridges to extract the pesticides. The cartridges were dried with carbon dioxide and the pesticides were eluted with three cartridge volumes of hexane:diethyl ether (1:1) solution. The eluants were analyzed using capillary-column gas chromatography/mass spectrometry in full-scan mode. Method detection limits for pesticides ranged from 0.002 to 0.025 microgram per liter for 1-liter samples. Recoveries ranged from 44 to 140 percent for 25 pesticides in samples of organic-free reagent water and Sacramento-San Joaquin Delta and Suisun Bay water fortified at 0.05 and 0.50 microgram per liter. The estimated holding time for pesticides after extraction on C-8 solid-phase extraction cartridges ranged from 10 to 257 days.

Crepeau, Kathryn L.; Baker, Lucian M.; Kuivila, Kathryn M.

2000-01-01

177

Structure and function of assemblages of Bacteria and Archaea in model anaerobic aquifer columns: can functional instability be practically beneficial?  

PubMed

Biodegradable organic carbon is often added to aquifers to stimulate microbial reduction of oxidized contaminants. This carbon also stimulates fermenters, which generate important metabolites that can fuel contaminant reduction and may enhance dissolution of hydrophobic compounds. Therefore, understanding how different methods of carbon addition affect the fermentative community will enable design of more effective remediation strategies. Our research objective was to evaluate the microbial communities that developed in model aquifer columns in response to pulsed or continuous molasses input. Results indicated that the continuously fed column produced relatively low concentrations of metabolic intermediates and had a greater proportion of Bacteria and methanogens, as measured by quantitative polymerase chain reaction, near the column inlet. In contrast, the pulsed-fed column generated periodic high concentrations of metabolic intermediates, with Bacteria and methanogens distributed throughout the length of the column. The community structures of Bacteria and Archaea, measured via automated ribosomal intergenic spacer analysis, in the pulsed-fed column were significantly different from those in the control column (not fed). The microbial community composition of the continuously fed column, however, became increasingly similar to the control column along the column length. These results demonstrate that a strategy of pulsed carbon addition leads to activity that is associated with functional instability, in terms of the production of periodic pulses of fermentation products and changing carbon concentration, and may be advantageous for remediation by producing large quantities of beneficial intermediates and resulting in more homogenously distributed biomass. PMID:22873515

Nelson, Denice K; Lapara, Timothy M; Novak, Paige J

2012-09-18

178

SENSITIVITY ANALYSIS FOR SALTSTONE DISPOSAL UNIT COLUMN DEGRADATION ANALYSES  

SciTech Connect

PORFLOW related analyses supporting a Sensitivity Analysis for Saltstone Disposal Unit (SDU) column degradation were performed. Previous analyses, Flach and Taylor 2014, used a model in which the SDU columns degraded in a piecewise manner from the top and bottom simultaneously. The current analyses employs a model in which all pieces of the column degrade at the same time. Information was extracted from the analyses which may be useful in determining the distribution of Tc-99 in the various SDUs throughout time and in determining flow balances for the SDUs.

Flach, G.

2014-10-28

179

200 Gbit\\/s, 100km time-division-multiplexed optical transmission using supercontinuum pulses with prescaled PLL timing extraction and all-optical demultiplexing  

Microsoft Academic Search

A single channel, single polarisation 200 Gbit\\/s time-division-multiplexed optical transmission experiment is successfully demonstrated using optical short pulses generated by supercontinuum. A prescaled clock is recovered directly from the 200Gbit\\/s signal to drive an all-optical demultiplexer.

S. Kawanishi; H. Takara; T. Morioka; O. Kamatani; M. Saruwatari

1995-01-01

180

Double-column gas chromatography using packed pre-columns and glass capillary main columns.  

PubMed

Methods of column switching are described that make possible back-flushing, heart cutting and trapping. Conventional packed columns are employed as pre-columns for their high sample capacity, and glass capillary columns are used as the main columns for their high separation efficiency. Some typical examples of the application of double-column gas chromatography are presented: (1) solvent cutting for identification and exact quantitative determination of a phosphorus ester impurity in a sample of wheat flour (including trapping); (2) separation of trace amounts of methyl esters of fatty acids by means of back-flushing and trapping; (3) enrichment technique using trapping of trace elements in the front section of the capillary (plus solvent cutting, multiple injection and back-flushing); and (4) coupling a nitrogen-selective detector to the capillary main column to gain additional information. To illustrate the trapping effect, the separation number was determined with and without trapping. PMID:548547

Blass, W; Riegner, K; Hulpke, H

1979-04-21

181

Momentum spectra of electrons rescattered from rare-gas targets following their extraction by one- and two-color femtosecond laser pulses  

SciTech Connect

We have used velocity-map imaging to measure the three-dimensional momenta of electrons rescattered from Xe and Ar following the liberation of the electrons from these atoms by 45 fs, 800 nm intense laser pulses. Strong structure in the rescattering region is observed in both angle and energy, and is interpreted in terms of quantitative rescattering (QRS) theory. Momentum images have also been taken with two-color (800 nm + 400 nm) pulses on Xe targets. A strong dependence of the spectra on the relative phase of the two colors is observed in the rescattering region. Interpretation of the phase dependence using both QRS theory and a full solution to the time-dependent Schroedinger equation shows that the rescattered electrons provide a much more robust method for determining the relative phase of the two colors than do the direct electrons.

Ray, D.; Chen Zhangjin; De, S.; Cao, W.; Le, A. T.; Lin, C. D.; Cocke, C. L. [J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506-2601 (United States); Litvinyuk, I. V. [J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506-2601 (United States); Centre for Quantum Dynamics, Griffith University, Nathan, Queensland 4111 (Australia); Kling, M. F. [J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506-2601 (United States); Max-Planck Institut fur Quantenoptik, D-85748 Garching (Germany)

2011-01-15

182

Preconcentration and separation of copper, nickel and zinc in aqueous samples by flame atomic absorption spectrometry after column solid-phase extraction onto MWCNTs impregnated with D2EHPA-TOPO mixture  

Microsoft Academic Search

A solid phase extraction method has been developed for the determination of copper, nickel and zinc ions in natural water samples. This method is based on the adsorption of copper, nickel and zinc on multiwalled carbon nanotubes (MWCNTs) impregnated with di-(2-ethyl hexyl phosphoric acid) (D2EHPA) and tri-n-octyl phosphine oxide (TOPO). The influence of parameters such as pH of the aqueous

S. Vellaichamy; K. Palanivelu

2011-01-01

183

A combined liquid three-phase micro-extraction and differential pulse voltammetric method for preconcentration and detection of ultra-trace amounts of buprenorphine using a modified pencil electrode.  

PubMed

A combination of polytetrafluorethylene membrane-based liquid three-phase micro-extraction and voltammetry was used for the micro-separation and determination of buprenorphine. Type of the organic solvent used, pH levels of the donor and acceptor phases, salt concentration, extraction time, stirring rate, and electrochemical parameters as the essential factors affecting the liquid three-phase micro-extraction of buprenorphine were investigated. Differential pulse voltammetry exhibited two linear dynamic ranges of 1.0-109.0 pmol L(-1) and 0.109 nmol L(-1)-0.11 µmol L(-1) of buprenorphine and the detection limit was found to be as low as 0.6 pmol L(-1) of buprenorphine. Also, the effects of a number of common substances potentially interfering with selectivity were studied. The results indicate that the proposed method is highly selective and sensitive for buprenorphine detection in real samples such as human urine and plasma of both drug-addict and non-addict human subjects. PMID:24148523

Ensafi, Ali A; Khoddami, Elaheh; Rezaei, B

2013-11-15

184

Density Column Lab - Part 2  

NSDL National Science Digital Library

Concluding a two-part lab activity, students use triple balance beams and graduated cylinders to take measurements and calculate densities of several household liquids and compare them to the densities of irregularly shaped objects (as determined in Part 1). Then they create density columns with the three liquids and four solid items to test their calculations and predictions of the different densities. Once their density columns are complete, students determine the effect of adding detergent to the columns. After this activity, present the associated Density & Miscibility lesson for a discussion about why the column layers do not mix.

GK-12 Program,

185

Compact electron beam focusing column  

SciTech Connect

A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2-D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani

2001-07-13

186

Five-Layer Density Column  

NSDL National Science Digital Library

In this activity, learners can create five-layer density columns by employing one of three (or all) methods. Method 1 gives the names of the liquids and the order for adding them, and its goal is to directly construct the density column without any experimentation. Method 2 assumes names and densities of the five materials to be unknown, and involves open-ended experimenting, with few instructions, to construct the column. Method 3 also assumes names and densities of the materials to be unknown, and outlines a systematic way to approach the experimentation involved in constructing the column. Learners complete data tables and analyze the densities of the substances.

Rathjen, Don

2005-01-01

187

Performance analysis of rotating disc contactor (RDC) column  

NASA Astrophysics Data System (ADS)

Liquid-liquid extraction is one of the most important separation processes. Different kinds of liquid-liquid extrator such as Rotating Disc Contactor (RDC) Column being used in industries. The study of liquid-liquid extraction in an RDC column has be come a very important subject to be discussed not just amongst chemical engineers but mathematicans as well. In this study, the performance of small diameter column RDC using the chemical system involving cumene/isobutryric asid/water are analyzed by the method of design of the experiments (DOE). DOE are applied to estimated the effect of four independent variable; protor speed, flow rate, concentration of continuous inlet and dispersed inlet and their interaction factor to detemine the most significant factor that effect the concentration of continuous and dispersed outlet as output parameters.

Aiffah, Wan Nurul; Aisyah, Siti; Fashihah, Nor; Anuar, Khairil

2014-06-01

188

SIGMM Education Column December 2010  

E-print Network

commonly used to analyze and solve multimedia research problems. The course was proposed for two reasons were consulted to identify a common core to go into CS5240. This initial list was still deemed tooSIGMM Education Column December 2010 SIGMM Education Column Authors: Wei Tsang Ooi and Terence Sim

Sim, Terence

189

Mush Column Magma Chambers  

NASA Astrophysics Data System (ADS)

Magma chambers are a necessary concept in understanding the chemical and physical evolution of magma. The concept may well be similar to a transfer function in circuit or time series analysis. It does what needs to be done to transform source magma into eruptible magma. In gravity and geodetic interpretations the causative body is (usually of necessity) geometrically simple and of limited vertical extent; it is clearly difficult to `see' through the uppermost manifestation of the concentrated magma. The presence of plutons in the upper crust has reinforced the view that magma chambers are large pots of magma, but as in the physical representation of a transfer function, actual magma chambers are clearly distinct from virtual magma chambers. Two key features to understanding magmatic systems are that they are vertically integrated over large distances (e.g., 30-100 km), and that all local magmatic processes are controlled by solidification fronts. Heat transfer considerations show that any viable volcanic system must be supported by a vertically extensive plumbing system. Field and geophysical studies point to a common theme of an interconnected stack of sill-like structures extending to great depth. This is a magmatic Mush Column. The large-scale (10s of km) structure resembles the vertical structure inferred at large volcanic centers like Hawaii (e.g., Ryan et al.), and the fine scale (10s to 100s of m) structure is exemplified by ophiolites and deeply eroded sill complexes like the Ferrar dolerites of the McMurdo Dry Valleys, Antarctica. The local length scales of the sill reservoirs and interconnecting conduits produce a rich spectrum of crystallization environments with distinct solidification time scales. Extensive horizontal and vertical mushy walls provide conditions conducive to specific processes of differentiation from solidification front instability to sidewall porous flow and wall rock slumping. The size, strength, and time series of eruptive behavior of the system, coupled with these processes, define the fundamental compositional and dynamic diversity of the Mush Column. In some ways it functions like a complex musical instrument. Entrainment, transport, and sorting of cumulate crystals as a function of repose time and the local flux intensity also contribute to the basic compositional diversity of the system. In the Ferrar dolerite system, about 104 km3 of dolerite is distributed throughout a fir-tree like stack of 4 or 5 extensive 300-750 m thick sills. The lowest sill contains a vast tongue of entrained orthopyroxene (opx) cumulates emplaced with the sill itself. The bulk sill composition varies from 20 pc MgO in the tongue center to 7 pc in the leading tip and margins of the sill, which itself defines the compositional spectrum of the whole complex and is remarkably similar to that exhibited by Hawaii. Relative sorting of large (1-50 mm) opx and small (1-3 mm) plagioclase due to kinetic sieving in the tongue produces pervasive anorthosite stringers. Through local ponding this has culminated in the formation of a small, well-formed layered intrusion consisting of alternating layers of orthopyroxenite and anorthosite. Upwards in the system the sills become progressively depleted in MgO and temporally and spatially contiguous flood basalts are low MgO tholeiites with no sign of opx cumulates. The size, extent, number of sills, and the internal structure of individual sills suggest a rhythm of injection similar to that of volcanic episodes. The continued horizontal stretching of a system of this type would lead to processes as recorded by ophiolites, and the repeated injection into a single reservoir would undoubtedly lead to a massive layered intrusion or to a series of high-level nested plutons.

Marsh, B. D.

2002-12-01

190

Seismic behavior of lightweight concrete columns  

NASA Astrophysics Data System (ADS)

Sixteen full-scale, column-beam assemblies, which represented a portion of a frame subjected to simulated seismic loading, were tested. Controlled test parameters included concrete type, column size, amount of main column steel, size and spacing of column confining hoops, and magnitude of column axial load. The columns were subjected to constant axial load and slow moment reversals at increasing inelastic deformations. Test data showed that properly designed lightweight concrete columns maintained ductility and strength when subjected to large inelastic deformations from load reversals. Confinement requirements for normal weight concrete columns were shown to be applicable to lightweight concrete columns up to thirty percent of the design strength.

Rabbat, B. G.; Daniel, J. I.; Weinmann, T. L.; Hanson, N. W.

1982-09-01

191

Microbial activity in weathering columns.  

PubMed

The aim of the present work was to evaluate the metabolic activity of the microbial population associated with a pyritic tailing after a column-weathering test. For this purpose, a column 150cm high and 15cm diameter was used. The solid was a tailing with 63.4% pyrite and with minor amounts of Cu, Pb and Zn sulfides (1.4, 0.5 and 0.8%, respectively). The column model was the habitual one for weathering tests: distilled water was added at the top of the column; the water flowed down through tailings and finally was collected at the bottom for chemical and microbiological analysis. Weathering was maintained for 36 weeks. The results showed a significant presence of microbial life that was distributed selectively over the column: sulfur- and iron-oxidizing aerobic bacteria were in the more oxygenated zone; anaerobic sulfur-reducing bacteria were isolated from the samples taken from the anoxic part of the column. Activity testing showed that (oxidizing and reducing) bacteria populations were active at the end of the weathering test. The quality of the water draining from the column was thus the final product of biological oxidation and reduction promoted by the bacteria consortia. PMID:16949201

García, C; Ballester, A; González, F; Blázquez, M L

2007-03-22

192

Comparison of Passive Samplers for Monitoring Dissolved Organic Contaminants in Water Column Deployments  

EPA Science Inventory

Nonionic organic contaminants (NOCs) are difficult to measure in the water column due to their inherent chemical properties resulting in low water solubility and high particle activity. Traditional sampling methods require large quantities of water to be extracted and interferen...

193

Liquid--liquid extraction apparatus. [for extracting mercaptans from hydrocarbon over wide range of flow rates  

Microsoft Academic Search

High efficiency in extraction operations, such as extracting mercaptans from hydrocarbons with caustic, is obtained over a wide range of flow rates through a single extraction column by the provision of an intermediate product drawoff means located between a downstream section of extraction trays having greatest efficiency at low throughputs and an upstream section of trays having peak efficiency at

Christman

1977-01-01

194

An accretion column model for the accreting pulsar Her X-1  

NASA Astrophysics Data System (ADS)

A model is developed here to reproduce the pulse shape of Her X-1. The 35-d cycle of pulse shape changes during the 35-d Her X-1 cycle `high-low-short-high-low' is caused by varying obscuration of the emission region by the accretion disc. The observed sequence of pulse shape changes imply a pencil beam from the near pole and a fan beam from the far pole. A newly developed code for modelling accretion column emission, which includes accurate treatment of gravitational light-bending effects and allows for various emissivity functions and for various geometrical asymmetries, is used to calculated model pulse profiles. The model profiles can reproduce the main features of the observed pulse profiles of Her X-1 in various energy bands. The resulting properties of the accretion column geometry and the emissivity function are given.

Leahy, D. A.

2004-03-01

195

Self-regenerating column chromatography  

DOEpatents

The present invention provides a process for treating both cations and anions by using a self-regenerating, multi-ionic exchange resin column system which requires no separate regeneration steps. The process involves alternating ion-exchange chromatography for cations and anions in a multi-ionic exchange column packed with a mixture of cation and anion exchange resins. The multi-ionic mixed-charge resin column works as a multi-function column, capable of independently processing either cationic or anionic exchange, or simultaneously processing both cationic and anionic exchanges. The major advantage offered by the alternating multi-function ion exchange process is the self-regeneration of the resins.

Park, Woo K. (Centerville, OH)

1995-05-30

196

Dynamic variability of column ozone  

NASA Technical Reports Server (NTRS)

A first-order, analytic estimate of the dynamical change in column ozone density is given as a function of temperature change in the lower stratosphere. It is found that, for each 1 percent (about 2 C) cooling averaged over the lower stratosphere, the column ozone density can be expected to decrease by approximately 7 percent, if it can be assumed that such a temperature change is induced by changes in wave transports.

Tung, Ka Kit; Yang, HU

1988-01-01

197

SEISMIC PERFORMANCE OF UFC SEGMENT COLUMNS  

NASA Astrophysics Data System (ADS)

Under an extreme ground motion, flexural capacity of a RC column deteriorates due to crushing of the core concrete and buckling of longitudinal bars. Therefore, it is important to prevent damage at the plastic hinge region for enhancing the seismic performance of RC columns. Two UFC segment columns which use UFC segments at the plastic hinge region and unbonded longitudinal bars are proposed; 1) in-core RC type column, and 2) PC cable type column. The seismic performance of two columns were clarified based on cyclic loading experiments. It is shown that the in-core RC type column shows better performance than the PC cable type column.

Ichikawa, Shota; Zhang, Rui; Sasaki, Tomohiro; Kawashima, Kazuhiko; Elgawady, Mohamed; Matsuzaki, Hiroshi; Yamanobe, Shinichi

198

Fast GCxGC with short primary columns.  

PubMed

A novel approach to comprehensive two-dimensional gas chromatography (GCxGC) separations is presented, which operates in a new region of the "GCxGC optimization pyramid". The technique relies on the use of short primary columns to decrease elution temperatures (Te) of analytes from the primary column, with a Te reduction of up to 50 degrees C illustrated. This in turn has implications that will expand the areas where GCxGC can be used, as decreased elution temperatures will allow GCxGC to be applied to mixtures of less volatile compounds or permit the use of less thermally stable stationary phases in the column ensemble. As well, it will allow GCxGC to be applied to thermally labile compounds through a reduction in elution temperature. With short primary columns, resolution and efficiency in the first dimension is sacrificed, but speed is gained; however, the second column in GCxGC provides additional resolution and separation of compounds of differing chemical properties. Thus, it is possible to recover some of the analytical separation power of the system to provide resolution of target analytes from sample impurities. As an example, a case study using short primary columns for the separation of natural pyrethrins, which degrade above 200 degrees C, is described. Even with the sacrifices of overall separation power that are made, there is still sufficient resolution available to separate the six natural pyrethrins from each other and the complex chrysanthemum extract matrix. The use of cold-on-column injection, a short primary column, and a high carrier gas flow rate allow the pyrethrins to be eluted below 200 degrees C, with separation in 17 min and complete resolution from sample matrix. PMID:16536442

Harynuk, James; Marriott, Philip J

2006-03-15

199

BEAM EXTRACTION FROM THE MURA 50 Mev FFAG ACCELERATOR  

Microsoft Academic Search

The components, operation, and performance of the beam extraction system ; are described, and the selection and proporties of particle orbits in the ; extraction channel are discussed. Single accelerated beam pulses were observed ; to last 37 nsec, and 40 mamp per pulse currents were measured in the extracted ; beam. The 45-Mev stacked beam was also extracted in

F. E. Mills; G. M. Lee; H. K. Meier; J. E. OMeara; C. H. Pruett; E. M. Rowe; C. A. Radmer; M. F. Shea; D. A. Swenson; D. E. Young

1963-01-01

200

Terahertz generation by an amplitude-modulated Gaussian laser beam in a rippled density plasma column  

Microsoft Academic Search

The nonlinear interaction of amplitude-modulated two-dimensional and three-dimensional laser beams with a cylindrical plasma column and the generation of terahertz (THz) radiation are studied. The plasma column could be formed by a cylindrically symmetric laser pre-pulse impinging on a gas jet target. A two-dimensional Gaussian laser beam propagating through the plasma exerts a ponderomotive force on electrons, imparting on them

Deepak Tripathi; Lalita Bhasin; R. Uma; V. K. Tripathi

2010-01-01

201

Integrated column arithmetic according to progressive schematisation  

Microsoft Academic Search

Following an introduction on the relation between column arithmetic and mental arithmetic in connection with the development of pocket calculators and computers, the characteristics of progressive schematisation are described with regard to column multiplication and column division. In this way, an image is formed of the specific characteristics of this approach to column arithmetic set against the background of traditional

A. Treffers

1987-01-01

202

Capacitor discharge pulse analysis.  

SciTech Connect

Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

2013-08-01

203

A quick cogener specific analysis of polychlorinated biphenyls in municipal sludge utilizing ultrasonic extraction and capillary gas chromatography  

SciTech Connect

At the Madison Metropolitan Sewerage District (MMSD) land application is a routine procedure for recycling municipal digested sludge. In 1982 analyses performed by MMSD indicated some areas of the sludge storage lagoons had polychlorinated biphenyl (PCB) levels greater than 50 parts per million (ppm), the EPA established limit for unrestricted land application of sludge. Conflicting test results obtained from commercial laboratories prompted MMSD to find the most reliable test method and also maximize the amount of information received from each analysis. Therefore, an accurate and precise measurement of PCBs in sludge was desired on a daily and sometimes hourly basis. Analysis of sludge samples by soxhlet extraction (SW846 method 3540B) and capillary gas chromatography (GC) required overnight extraction, 2-3 hours extract cleanup and concentration, plus 3 hours elution time on a narrow bore column to achieve a congener specific analysis. A procedure to obtain congener specific PCB data in 2-2.5 hours was developed using ultrasonic extraction (SW846 method 3550B), florisil mini-cartridge cleanup and a 20-meter narrow bore column. Small homogeneous samples of sludge (2-4 grams) were mixed with the extracting solvent in a 50 mL centrifuge tube and then extracted using a sonic dismemberator in the pulsed mode. A 20-meter length was cut from a 60-meter, 0.25 mm i.d. capillary column. Resolution of some of the 95 congeners present was sacrificed to obtain a GC run time of 23 minutes. Sludges ranging from 2% to 30% solids were routinely analyzed with concentrations from detection limits to 200 ppm dry weight. Comparison of the sonication vs. soxhlet extractions exhibited no significant difference in the amount of PCBs recovered from various samples.

Hughes, W.L. [Madison Metropolitan Sewerage District, Madison, WI (United States)

1994-12-31

204

Monolithic molecularly imprinted polymeric capillary columns for isolation of aflatoxins.  

PubMed

Monolithic molecularly imprinted polymers extraction columns have been prepared in fused-silica capillaries by UV or thermal polymerization in a two-step process. First, a poly-(trimethylolpropane trimethacrylate) (polyTRIM) core monolith was synthesized either by UV or thermal polymerization. Then it was grafted with the mixture of methacrylic acid (MAA) as a functional monomer, ethylene dimethacrylate (EDMA) as a cross-linking agent, 5,7-dimethoxycoumarin (DMC) as an aflatoxin-mimicking template, toluene as a porogen solvent and 2,2-azobis-(2-methylpropionitrile) (AIBN) as an initiator of the polymerization reaction. Different thermal condition of the photografting and different concentrations of the grafting mixture were tested during polymerization. The extraction capillary columns were evaluated in the terms of their hydrodynamic and chromatographic properties. Retention coefficients for aflatoxin B1 and DMC were used for assessment of the selectivity and imprinting factor. The obtained results indicate that the temperature of photografting and concentration of the grafting mixture are key parameters that determine the quality of the prepared MIPs. From the MIP columns characterized by the highest permeability the column of the highest imprinting factor was applied for isolation of aflatoxins B1, B2, G1 and G2 from the model aqueous sample followed by on-line chromatographic separation. The process was performed using a micro-MISPE-microLC-LIF system of a novel design, which allowed for detection of the eluates from the sample preparation part as well as from the chromatographic separation. PMID:25218633

Szumski, Micha?; Grzywi?ski, Damian; Prus, Wojciech; Buszewski, Bogus?aw

2014-10-17

205

SNS EXTRACTION KICKER POWER SUPPLY MANUFACTURE STATUS  

Microsoft Academic Search

There are fourteen PFN power supplies, which will be installed in the SNS Extraction Kicker System. The Pulse Forming Network (PFN) power supplies for the SNS Extraction kicker were designed by Brookhaven. The basic configuration of the PFN is a lumped element Blumlein pulse forming network (BPFN). The PFN and power supply are fabricated by Applied Power Systems. The first-article

Jian-Lin Mi; H. Hahn; R. Lambiase; Y. Y. Lee; C. Pai; J. Sandberg; Y. Tan; N. Tsoupas; D. Warburton; R. Zapasek; W. Zhang

2004-01-01

206

Selected Topics in Column Generation  

E-print Network

Dec 2, 2002 ... real-time dispatching of automobile service units. Lübbecke and ...... the dominating column in a post-processing phase. ... anyway, e.g., shortest path problems, the lower bound on the optimal integral z? in (15) obtained from.

2002-12-02

207

Method for liquid chromatographic extraction of strontium from acid solutions  

DOEpatents

A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

Horwitz, E. Philip (Naperville, IL); Dietz, Mark L. (Evanston, IL)

1992-01-01

208

Rapid reversed-phase liquid chromatography separation of cyclolinopeptides with monolithic and microparticulate columns.  

PubMed

Three monolithic C(18)-bonded silica gel columns i.e. Chromolith SpeedROD (CSR), Chromolith Performance (CP), and Chromolith High Resolution (CHR), MerckKGaA Darmstadt, Germany and two particle-based columns i.e. ZORBAX Eclipse XDB-C(18) (ZEX), Agilent and POROS R1/20 (POR), Applied Biosystems were compared for their performance in separating a mixture of flaxseed cyclolinopeptides (CLs). Gradient mobile phases of acetonitrile and water were optimized for each column. The performance of CHR column in profiling CL standards, measured as the resolution of individual CL, selectivity, and peak asymmetry exceeded the performance of traditional particle-packed columns and the other monolithic columns. The profiling of CLs in aqueous methanolic flaxseed extract was optimized for high-throughput analysis. A total analysis time of 1.5 min at a flow rate of 3.0mLmin(-1) was achieved on a CSR column. Injection of over 2000 methanol extracts of flaxseed on a CSR column had no impact on backpressure or resolution of a standard CL mixture. PMID:22898105

Olivia, Clara M; Burnett, Peta-Gaye G; Okinyo-Owiti, Denis P; Shen, Jianheng; Reaney, Martin J T

2012-09-01

209

"Supermarket Column Chromatography of Leaf Pigments" Revisited: Simple and Ecofriendly Separation of Plant Carotenoids, Chlorophylls, and Flavonoids from Green and Red Leaves  

ERIC Educational Resources Information Center

A simple and ecofriendly procedure was developed in order to prepare extracts from red and green leaves. This procedure enables the separation of yellow, green, and red band pigments and optimizes the previously reported baking soda "supermarket column". The same extract also led to a novel and colorful potato starch column, which can…

Dias, Alice M.; Ferreira, Maria La Salete

2015-01-01

210

Modeling and control of a 75 kW class variable liquid-column oscillator for highly efficient wave energy converter  

Microsoft Academic Search

The modeling and control of a variable liquid-column oscillator having a liquid filled U-tube with air chambers at its vertical columns are presented. As an ocean wave energy extracting device, the structure of the variable liquid-column oscillator (VLCO) is analogous to that of the tuned liquid-column damper used to suppress oscillatory motion in large structures like tall buildings and cargo

Byung-Hak Cho; Dong-Soon Yang; Shin-Yeol Park; Kyung-Shik Choi; Do-Hwan Lee; Seung-Hyun Byun; Hoon Jung

2011-01-01

211

Extraction chromatography: Progress and opportunities  

SciTech Connect

Extraction chromatography provides a simple and effective method for the analytical and preparative-scale separation of a variety of metal ions. Recent advances in extractant design, particularly the development of extractants capable of metal ion recognition or of strong complex formation in highly acidic media, have significantly improved the utility of the technique. Advances in support design, most notably the introduction of functionalized supports to enhance metal ion retention, promise to yield further improvements. Column instability remains a significant obstacle, however, to the process-scale application of extraction chromatography. 79 refs.

Dietz, M.L.; Horwitz, E.P.; Bond, A.H. [Argonne National Lab., IL (United States). Chemistry Div.

1997-10-01

212

Influence of biodegradation on carbazole and benzocarbazole distributions in oil columns from the Liaohe basin, NE China  

Microsoft Academic Search

Alkylcarbazoles and benzocarbazoles in petroleum reservoir core extracts isolated from several oil columns within the Lengdong oilfield, Liaohe basin, China were studied to investigate their occurrence and the effect of biodegradation on their concentrations and distributions. Bulk petroleum composition and molecular data indicate the occurrence of systematic biodegradation gradients within the oil columns, the extent of biodegradation ranging from light

Haiping Huang; Bernard F. J. Bowler; Zhanwen Zhang; Thomas B. P. Oldenburg; Steve R. Larter

2003-01-01

213

Density Column Lab - Part 1  

NSDL National Science Digital Library

In this first part of a two-part lab activity, students use triple balance beams and graduated cylinders to take measurements and calculate the densities of several common, irregularly shaped objects with the purpose to resolve confusion about mass and density. After this activity, conduct the associated Density Column Lab - Part 2 activity before presenting the associated Density & Miscibility lesson for discussion about concepts that explain what students have observed.

GK-12 Program,

214

Comparison of Passive Samplers for Monitoring Dissolved Organic Contaminants in Water Column Deployments (SETAC Europe 22nd Annual Meeting)  

EPA Science Inventory

Nonionic organic contaminants (NOCs) are difficult to measure in the water column due to their inherent chemical properties resulting in low water solubility and high particle activity. Traditional sampling methods require large quantities of water to be extracted and interferen...

215

Comparison of Passive Samplers for Monitoring Dissolved Organic Contaminants in Water Column Deployments NAC/SETAC 2012  

EPA Science Inventory

Nonionic organic contaminants (NOCs) are difficult to measure in the water column due to their inherent chemical properties resulting in low water solubility and high particle activity. Traditional sampling methods require large quantities of water to be extracted and interferen...

216

High current short pulse ion sources  

SciTech Connect

High current short pulse ion beams can be generated by using a multicusp source. This is accomplished by switching the arc or the RF induction discharge on and off. An alternative approach is to maintain a continuous plasma discharge and extraction voltage but control the plasma flow into the extraction aperture by a combination of magnetic and electric fields. Short beam pulses can be obtained by using a fast electronic switch and a dc bias power supply. It is also demonstrated that very short beam pulses ({approximately} 10 {micro}s) with high repetition rate can be formed by a laser-driven LaB{sub 6} or barium photo-cathode.

Leung, K.N. [Lawrence Berkeley National Lab., CA (United States). Accelerator and Fusion Research Div.

1996-08-01

217

Method for packed column separations and purifications  

SciTech Connect

The invention encompasses a method of packing and unpacking a column chamber. A mixture of a fluid and a matrix material are introduced through a column chamber inlet so that the matrix material is packed within a column chamber to form a packed column. The column chamber having the column chamber inlet or first port for receiving the mixture further has an outlet port and an actuator port. The outlet port is partially closed for capturing the matrix material and permitting the fluid to flow therepast by rotating relative one to the other of a rod placed in the actuator port. Further rotation relative one to the other of the rod and the column chamber opens the outlet and permits the matrix material and the fluid to flow therethrough thereby unpacking the matrix material from the column chamber.

Holman, David A. (Richland, WA); Bruckner-Lea, Cynthia J. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Chandler, Darrell P. (Richland, WA)

2006-08-15

218

EFFICIENCY OF DIOXIN RECOVERY FROM FLY ASH SAMPLES DURING EXTRACTION AND CLEANUP PROCESS  

EPA Science Inventory

The data from preliminary investigations of the efficiency of dioxin recovery from fly ash samples during sample extraction and subsequent column cleanup of sample extracts are discussed. teps of the extraction and the column cleanup procedures were evaluated by using radiolabele...

219

Sensitive column-switching high-performance liquid chromatography method for determination of propiverine in human plasma  

Microsoft Academic Search

A sensitive column-switching high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was developed for the determination of propiverine in human plasma. Propiverine and internal standard, oxybutynin, were extracted from human plasma that had been made basic with 5N sodium hydroxide into methyl tert-butyl ether. The extracted plasma sample was injected onto the HPLC system consisting of a pretreatment column, a

Eunmi Ban; Jeong-Eun Maeng; Jong Soo Woo; Chong-Kook Kim

2006-01-01

220

Stratigraphic Columns Across Southern Western Interior  

NSDL National Science Digital Library

This website depicts stratigraphic columns of exposed rocks in southwestern regions of the United States. A general explanation of symbols used in the columns is provided for reference, and the columns indicate rock type, formation names and geologic time periods. The areas covered include the Grand Canyon, central and southern Arizona, southern Utah and Nevada, and western New Mexico and Colorado.

Blakey, Ronald

221

29 CFR 1926.755 - Column anchorage.  

...anchor rods (anchor bolts). (2) Each column anchor rod (anchor bolt) assembly, including the column-to-base plate weld and the column foundation, shall be designed to resist a minimum eccentric gravity load of 300 pounds (136.2 kg)...

2014-07-01

222

Water column correction for coral reef studies by remote sensing.  

PubMed

Human activity and natural climate trends constitute a major threat to coral reefs worldwide. Models predict a significant reduction in reef spatial extension together with a decline in biodiversity in the relatively near future. In this context, monitoring programs to detect changes in reef ecosystems are essential. In recent years, coral reef mapping using remote sensing data has benefited from instruments with better resolution and computational advances in storage and processing capabilities. However, the water column represents an additional complexity when extracting information from submerged substrates by remote sensing that demands a correction of its effect. In this article, the basic concepts of bottom substrate remote sensing and water column interference are presented. A compendium of methodologies developed to reduce water column effects in coral ecosystems studied by remote sensing that include their salient features, advantages and drawbacks is provided. Finally, algorithms to retrieve the bottom reflectance are applied to simulated data and actual remote sensing imagery and their performance is compared. The available methods are not able to completely eliminate the water column effect, but they can minimize its influence. Choosing the best method depends on the marine environment, available input data and desired outcome or scientific application. PMID:25215941

Zoffoli, Maria Laura; Frouin, Robert; Kampel, Milton

2014-01-01

223

Water Column Correction for Coral Reef Studies by Remote Sensing  

PubMed Central

Human activity and natural climate trends constitute a major threat to coral reefs worldwide. Models predict a significant reduction in reef spatial extension together with a decline in biodiversity in the relatively near future. In this context, monitoring programs to detect changes in reef ecosystems are essential. In recent years, coral reef mapping using remote sensing data has benefited from instruments with better resolution and computational advances in storage and processing capabilities. However, the water column represents an additional complexity when extracting information from submerged substrates by remote sensing that demands a correction of its effect. In this article, the basic concepts of bottom substrate remote sensing and water column interference are presented. A compendium of methodologies developed to reduce water column effects in coral ecosystems studied by remote sensing that include their salient features, advantages and drawbacks is provided. Finally, algorithms to retrieve the bottom reflectance are applied to simulated data and actual remote sensing imagery and their performance is compared. The available methods are not able to completely eliminate the water column effect, but they can minimize its influence. Choosing the best method depends on the marine environment, available input data and desired outcome or scientific application. PMID:25215941

Zoffoli, Maria Laura; Frouin, Robert; Kampel, Milton

2014-01-01

224

Winogradsky Column Unit: Chemical and Physical Change  

NSDL National Science Digital Library

This two-part activity leads Physical Science students, grades 8-12, to explore chemical change using Winogradsky Columns. Part 1 constructs student concepts concerning chemical and physical changes. Part 2 asks students to compare physical versus chemical changes and observe chemical changes in a Winogradsky Column, and teaches them to build their own column. It includes the following student pages: introductory lesson, Winogradsky Column lesson, challenge your thinking activity sheet, how to make a Winogradsky Column, how to create an observation journal, and journal evaluation sheet.

Pevzner, Yevgeny; Shelton, Sharyn A.; Project, Westminster C.

225

Dry-Column Flash Chromatography  

NASA Astrophysics Data System (ADS)

Dry-column flash chromatography is a safe, powerful, yet easily learned preparative chromatography technique. It has proven useful in research, and an adaptation of the technique for use in large teaching laboratories (general chemistry, organic chemistry) is described here. The student version is similar to vacuum filtration, uses the same compact, readily available glassware, and inexpensive and safe solvents (ethyl acetate and hexane) and adsorbent (Merck grade 60 silica gel). The technique is sufficiently simple and powerful that a beginning student can successfully resolve diastereomers on sample scales ranging from 100 mg to >1 g.

Shusterman, Alan J.; McDougal, Patrick G.; Glasfeld, Arthur

1997-10-01

226

Purification of polar compounds from Radix isatidis using conventional C18 column coupled with polar-copolymerized C18 column.  

PubMed

Regarding hydrophilic interaction chromatography and normal phase liquid chromatography, RPLC is another choice used to separate polar compounds with the improvement of polar-modified C18 stationary phase. In this study, a method using conventional C18 column coupled with polar-copolymerized C18 column was successfully developed for the separation and purification of polar compounds from Radix isatidis, which is one of the most commonly used traditional Chinese medicines (TCMs). An XTerra MS C18 column was used to fractionate the extract of R. isatidis and a homemade polar-copolymerized C18 column was utilized for the final purification due to its good separation selectivity and high resolution for polar compounds. The established purification system demonstrated good orthogonality for the polar compounds. As a result, ten compounds were purified and three of them were identified as 3-methyl-5-vinyloxazolidin-2-one (compound A), 5-hydroxymethyl-2-furaldehyde (compound B) and 3-methylfuran-2-carboxylic acid (compound G) based on the MS, IR and extensive NMR data, respectively. It was demonstrated to be a feasible and powerful technique for the purification of polar compounds under RPLC mode and more chemical information of TCMs will be obtained to interpret the efficiency of TCMs. PMID:20886519

Zeng, Jing; Guo, Zhimou; Xiao, Yuansheng; Wang, Chaoran; Zhang, Xiuli; Liang, Xinmiao

2010-11-01

227

Digital Pulse  

NSDL National Science Digital Library

When high technology crashes into popular culture you've got Digital Pulse, the heartbeat of the infotainment infobahn with exclusive news and tips from the experts at CMP's Windows Magazine, NetGuide, Home PC and more. This week read about Adam Curry's deal with BMI which will let him sell (and us buy) digital recordings over the 'Net. Free registration is required on Pathfinder, Time Warner's home on the internet.

228

Pulsed hydrojet  

DOEpatents

An underwater pulsed hydrojet propulsion system is provided for accelerating and propelling a projectile or other vessel. A reactant, such as lithium, is fluidized and injected into a water volume. The resulting reaction produces an energy density in a time effective to form a steam pocket. Thrust flaps or baffles direct the pressure from the steam pocket toward an exit nozzle for accelerating a water volume to create thrust. A control system regulates the dispersion of reactant to control thrust characteristics.

Bohachevsky, I.O.; Torrey, M.D.

1986-06-10

229

Inspection on CFRP sheet with subsurface defects using pulsed thermographic technique  

NASA Astrophysics Data System (ADS)

The pulsed thermographic technique was used to detect flat-bottomed hole defects in CFRP sheet. Pulsed phase thermography (PPT) was used to extract the characteristic information of the thermal wave signal generated by thermal pulse. The difference of the phases between the sound and defective areas were analyzed. The defects' edges were extracted by Fuzzy C-Means clustering algorithm.

Chiwu, Bu; Qingju, Tang; Junyan, Liu; Yang, Wang

2014-07-01

230

Biotransformation of organics in soil columns and an infiltration area  

SciTech Connect

Laboratory column experiments were performed to evaluate the fate of a series of chlorinated and nonchlorinated organic contaminants in Rhine sediment and in sediment from the infiltration area of the Municipal Water Works of Amsterdam, near Zandvoort, The Netherlands. Columns were operated under aerobic, denitrifying, the methanogenic conditions. All nonchlorinated and few chlorinated compounds were aerobically transformed. Of the compounds tested under denitrifying conditions, only 1,2-dichloro-4-nitrobenzene was partially transformed. Methanogenic conditions favored the transformation of chlorinated substances by reductive dechlorination. Toluene was the only nonhalogenated compound that was transformed under methanogenic conditions. Steady-state effluent concentrations after biotransformation were at least 10 times lower than the drinking water limit of 1 {micro}g/l, except in the case of 1,2,4-trichlorobenzene which had a steady-state effluent concentration of 2.6 {micro}g/l. Steady-state effluent concentrations did not depend on the influent concentration applied. Most transformations proceeded at the same steady-state rates at a temperature of 4 C, although the process of reductive dechlorination was slower at 4 C than at 20 C. Hydrological calculations revealed that the combined action of hydrology and sorption to organic matter in the infiltration system can reduce the concentrations of 2 weeks pulses of polar and nonpolar contaminants by at least 80 and 95%, respectively. There was a good qualitative agreement between removals observed in column experiments and in the dune infiltration area.

Bosma, T.N.P.; Zehnder, J.B. [Agricultural Univ., Wageningen (Netherlands). Dept. of Microbiology]|[Swiss Federal Inst. for Environmental Science and Technology, Kastanienbaum (Switzerland); Ballemans, E.M.W.; Hoekstra, N.K.; Schraa, G. [Agricultural Univ., Wageningen (Netherlands). Dept. of Microbiology; Welscher, R.A.G. te; Smeenk, J.G.M.M. [Municipal Water Works of Amsterdam, Heemstede (Netherlands)

1996-01-01

231

Soil column leaching of pesticides.  

PubMed

In this review, I address the practical and theoretical aspects of pesticide soil mobility.I also address the methods used to measure mobility, and the factors that influence it, and I summarize the data that have been published on the column leaching of pesticides.Pesticides that enter the unsaturated soil profile are transported downwards by the water flux, and are adsorbed, desorbed, and/or degraded as they pass through the soil. The rate of passage of a pesticide through the soil depends on the properties of the pesticide, the properties of the soil and the prevailing environmental conditions.Because large amounts of many different pesticides are used around the world, they and their degradates may sometimes contaminate groundwater at unacceptable levels.It is for this reason that assessing the transport behavior and soil mobility of pesticides before they are sold into commerce is important and is one indispensable element that regulators use to assess probable pesticide safety. Both elementary soil column leaching and sophisticated outdoor lysimeter studies are performed to measure the leaching potential for pesticides; the latter approach more reliably reflects probable field behavior, but the former is useful to initially profile a pesticide for soil mobility potential.Soil is physically heterogeneous. The structure of soil varies both vertically and laterally, and this variability affects the complex flow of water through the soil profile, making it difficult to predict with accuracy. In addition, macropores exist in soils and further add to the complexity of how water flow occurs. The degree to which soil is tilled, the density of vegetation on the surface, and the type and amounts of organic soil amendments that are added to soil further affect the movement rate of water through soil, the character of soil adsorption sites and the microbial populations that exist in the soil. Parameters that most influence the rate of pesticide mobility in soil are persistence (DT50) of the pesticide, and its sorption/desorption(Koc) characteristics. These parameters may vary for the same pesticide from geographic site-to-site and with soil depth. The interactions that normally occur between pesticides and dissolved organic matter (DOM) or WDC are yet other factors that may complicate pesticide leaching behavior.The soil mobility of pesticides is normally tested both in the laboratory and in the field. Lab studies are initially performed to give researchers a preliminary appraisal of the relative mobility of a pesticide. Later, field lysimeter studies can be performed to provide more natural leaching conditions that emulate the actual field use pattern. Lysimeter studies give the most reliable information on the leaching behavior of a pesticide under field conditions, but these studies are time-consuming and expensive and cannot be performed everywhere. It is for this reason that the laboratory soil column leaching approach is commonly utilized to profile the mobility of a pesticide,and appraise how it behaves in different soils, and relative to other pesticides.Because the soil structure is chemically and physically heterogenous, different pesticide tests may produce variable DT50 and Koc values; therefore, initial pesticide mobility testing is undertaken in homogeneously packed columns that contain two or more soils and are eluted at constant flow rates. Such studies are done in duplicate and utilize a conservative tracer element. By fitting an appropriate mathematical model to the breakthrough curve of the conservative tracer selected,researchers determine key mobility parameters, such as pore water velocity, the column-specific dispersion coefficient, and the contribution of non equilibrium transport processes. Such parameters form the basis for estimating the probable transport and degradation rates that will be characteristic of the tested pesticide. Researchers also examine how a pesticide interacts with soil DOM and WDC, and what contribution from facilitated transport to mobility is made as a result of the effects of

Katagi, Toshiyuki

2013-01-01

232

Analysis of free and total myo-inositol in foods, feeds, and infant formula by high-performance anion exchange chromatography with pulsed amperometric detection, including a novel total extraction using microwave-assisted acid hydrolysis and enzymatic treatment.  

PubMed

A method for the analysis of free and total myo-inositol in foods, feeds, and infant formulas has been developed and validated using high-performance anion exchange chromatography with pulsed amperometric detection. The option of a free myo-inositol determination or a complete total myo-inositol determination from main bound sources can be achieved. These sources include phytates, lower'phosphorylated forms, and phosphatidylinositol. This approach gives the option for subtraction of myo-inositol from nonbioavailable sources when it is quantified using other methods if a total bioavailable myo-inositol result is desired for nutritional labeling of a product. The free analysis was validated in a milk-based infant formula, giving RSD(R) of 2.29% and RSD, of 2.06%. A mean recovery of 97.9% was achieved from various spike levels of myo-inositol. Certified National Institute of Standards and Technology reference material verified the method's compatibility and specificity. Two different total analyses were validated in a soy-based infant formula and compared. One technique involved using a conventional acid hydrolysis with autoclave incubation for 6 h, while the other used a novel technique of microwave-assisted acid hydrolysis with enzymatic treatment that can minimize extraction to 1 day. The autoclave analysis had RSD(R) of 2.08% and RSDr of 1.55%, along with a mean spike recovery of 102.1% at various myo-inositol spike levels. The microwave/enzyme total analysis had RSD(R) of 4.34% and RSD, of 4.70%, along with a mean spike recovery of 104.2% at various spike levels of myo-inositol. Main sources of myo-inositol including phytic acid and phosphatidylinositol were tested with both total analyses. Mean recoveries of phytic acid and phosphatidylinositol through the autoclave total analysis were 90.4 and 98.3%, respectively. Mean spike recoveries for these same sources in soy- based infant formula through the microwave/enzyme total analysis were 97.2 and 96.3%, respectively. Comparison of soy-based infant formula and corn grain samples with high levels of these main sources showed in similar results, indicating both total analyses are acceptable for use. An additional glycerol kinase step was also developed to remove glycerol from the chromatographic elution window of myoinositol in samples with high levels of glycerol. PMID:23175982

Ellingson, David; Pritchard, Ted; Foy, Pamela; King, Kathryn; Mitchell, Barbara; Austad, John; Winters, Doug; Sullivan, Darryl

2012-01-01

233

Enzyme activities in the water column and in shallow permeable sediments from the northeastern Gulf of Mexico  

NASA Astrophysics Data System (ADS)

The activities of extracellular enzymes that initiate the microbial remineralization of high molecular weight organic matter were investigated in the water column and sandy surface sediments at two sites in the northeastern Gulf of Mexico. Six fluorescently labeled polysaccharides were hydrolyzed rapidly in the water column as well as in permeable sediments. This result contrasts with previous studies carried out in environments dominated by fine-grained muds, in which the spectrum of enzymes active in the water column is quite limited compared to that of the underlying sediments. Extracts of Spirulina, Isochrysis, and Thalassiosira were also used to measure hydrolysis rates in water from one of the sites. Rates of hydrolysis of the three plankton extracts were comparable to those of the purified polysaccharides. The broad spectrum and rapid rates of hydrolysis observed in the water column at both sites in the northeastern Gulf of Mexico may be due to the permeable nature of the sediments. Fluid flux through the sediments is sufficiently high that the entire 1.5 m deep water column could filter though the sediments on timescales of a few days to two weeks. Movement of water through sediments may also transport dissolved enzymes from the sediment into the water column, enhancing the spectrum as well as the rate of water column enzymatic activities. Such interaction between the sediments and water column would permit water column microbial communities to access high molecular weight substrates that might otherwise remain unavailable as substrates.

Arnosti, C.; Ziervogel, K.; Ocampo, L.; Ghobrial, S.

2009-09-01

234

Disposable microliter immunoabsorbent columns: construction and operation.  

PubMed

Disposable microliter immunoabsorbent columns were constructed from pasteur pipets. The bed support was a cube of gelatin surgical sponge, which was tamped into the pipet tip. Column dead space, represented by the compressed volume of the sponge, was 5 microliters. The columns were used with protein A-Sepharose; settled bed volumes were 50 microliters. It was possible to pour columns that functioned as immunoabsorbents with bed volumes as small as 10 microliters. There was no gravity flow through these columns. Flow was achieved by touching column tips to absorbent paper if liquid was to be discarded or to 50 microliters capillary tubes for fluid collection. A simple capillary collection tube assembly was designed for operation of a row of 10 columns at a time. In a test system of [3H]methotrexate and IgG anti-methotrexate, 90% of applied antigen was bound to antibody columns, whereas 90% was recovered in the eluates from control columns. The columns were used in the initial step of screening uncloned hybridoma culture fluids for anti-MSP. PMID:3900218

Leonard, E J; Skeel, A

1985-10-10

235

Modelling failure of natural rock columns  

NASA Astrophysics Data System (ADS)

Natural rock columns often assume strange geometries that look unstable under the static loading of the rock mass itself and even more so under the resonance inducing, dynamic loads of seismic shaking. A two-dimensional finite element stress model was applied to the analysis of six selected rock columns formed in welded, horizontally jointed tuff in the Chiricahua Mountains, Arizona. The columns were selected for precarious appearing geometries, such as asymmetrical overhangs, narrow aspect, and severely incut "hourglass" profiles. In none of the cases did the stress modelling indicate proximity to either compressional or tensile failure. The modelling revealed that failure because of slip along inclined joints penetrating the rock was much more likely. Surprisingly, columns with pronounced "hourglass" morphologies were found to be more stable than cylindrical columns in rock with non-horizontal joints. The uniformity of column heights suggests that either rare, high velocity winds or prehistoric seismicity cropped the previous generation of columns. An estimate of the resonant frequencies of a typical column provides some idea of the dynamic response of the columns to seismic shaking. The question of seismic destruction is intriguing because the columns were apparently unaffected by a magnitude 7.2 earthquake 120 km away in 1887.

Hall, Douglas B.

1996-03-01

236

Millijoule pulse energy high repetition rate femtosecond fiber chirped-pulse amplification system.  

PubMed

We report on an ytterbium-doped fiber chirped-pulse amplification (CPA) system delivering millijoule level pulse energy at repetition rates above 100 kHz corresponding to an average power of more than 100 W. The compressed pulses are as short as 800 fs. As the main amplifier, an 80 microm core diameter short length photonic crystal fiber is employed, which allows the generation of pulse energies up to 1.45 mJ with a B-integral as low as 7 at a stretched pulse duration of 2 ns. A stretcher-compressor unit consisting of dielectric diffraction gratings is capable of handling the average power without beam and pulse quality distortions. To our knowledge, we present the highest pulse energy ever extracted from fiber based femtosecond laser systems, and a nearly 2 orders of magnitude higher repetition rate than in previously published millijoule-level fiber CPA systems. PMID:18087520

Röser, F; Eidam, T; Rothhardt, J; Schmidt, O; Schimpf, D N; Limpert, J; Tünnermann, A

2007-12-15

237

Supercritical fluid extraction on semibatch mode for the removal of terpene in citrus oil  

SciTech Connect

Supercritical carbon dioxide extraction of a mixture of limonene and linalool was carried out with a rectification column in the semibatch operation mode. For the simple semibatch extraction where the column was controlled at the uniform temperature without an internal reflux, the Rayleigh equation, developed for the simple batch distillation, was applied to express the dynamic extraction behavior. In this paper the Peng-Robinson equation of state was used to estimate the ternary phase equilibria. The semibatch extraction with internal flux induced by a temperature gradient of the rectification column increased the separation selectivity. The internal reflux ratio was calculated by the measurement of the extraction rates at the top and bottom of the column, and it was 7.6 for the column having a temperature gradient from 313 K at the bottom to 333 K at the top at 8.8 MPa. Behavior in the rectification column was discussed by means of estimated physical properties.

Sato, Masaki; Goto, Motonobu; Hirose, Tsutomu [Kumamoto Univ. (Japan)] [Kumamoto Univ. (Japan)

1996-06-01

238

Comparison of Several Extraction Methods for the Isolation of Benzoic Acid Derivatives from Melissa officinalis  

Microsoft Academic Search

Several extraction techniques, such as Soxhlet extraction, solid phase extraction using molecularly imprinted polymer, matrix solid phase dispersion, and supercritical fluid extraction were evaluated for the isolation and purification of phenolic compounds, e.g., benzoic acids from natural samples of Melissa officinalis. The extracts of benzoic acids were analyzed by high performance liquid chromatography (HPLC) in reversed phase modus (C18 column)

Gabriela Karasová; Jozef Lehotay; Ewa K?odzinska; Bogus?aw Buszewski

2006-01-01

239

IMAGING WITH THZ PULSES Timothy Dorney, Jon Johnson, Daniel Mittleman, Richard Baraniuk  

E-print Network

digital signal processing algorithms to extract useful information from the THz pulses. The possibility generate a coherent THz wave. The resulting electromagnetic pulse is broadband and spans from below 100 GHz laser pulse and the generated THz wave. Through this arrangement, the laser pulse acts as a gating

240

Tapered pulse tube for pulse tube refrigerators  

DOEpatents

Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

Swift, Gregory W. (Sante Fe, NM); Olson, Jeffrey R. (San Mateo, CA)

1999-01-01

241

The Winogradsky Column: An Animated Tutorial  

NSDL National Science Digital Library

This five-minute animated tutorial describes Winogradsky columns. The tutorial shows how to create a Winogradsky Column, describes the various layers and types of microbes in a column, and explains the interdependence and metabolic activities of the organisms. Users are given the choice of a "narrated" version or a "step-through" version in which each image is accompanied with text. The tutorial takes a moment to load.

Services, Sumanas I.

242

An exact algorithm for IP column generation  

Microsoft Academic Search

An exact column generation algorithm for integer programs with a large (implicit) number of columns is presented. The family of problems that can be treated includes not only standard partitioning problems such as bin packing and certain vehicle routing problems in which the columns generated have 0–1 compenents and a right-hand side vector of 1's, but also the cutting stock

François Vanderbeck; Laurence A. Wolsey

1996-01-01

243

Pulsed magnetic field-electron cyclotron resonance ion source operation  

SciTech Connect

The pulsed magnetic field (PuMa)-electron cyclotron resonance (ECR) ion source uses a pulsed coil to improve the peak current by opening the magnetic bottle along the beam axis. After demonstration of the principle of the pulsed magnetic extraction, the ion source was tested with different gases. We received promising results from helium to krypton. The influence of the current in the pulsed coil on the analyzed ion current was measured. With increased current levels within the pulsed coil not only the pulse height of the PuMa pulse, but the pulse length can also be controlled. By using the pulsed coil the maximum of the charge state distribution can be shifted to higher charge states. {copyright} {ital 1996 American Institute of Physics.}

Muehle, C.; Ratzinger, U.; Joest, G.; Leible, K.; Schennach, S.; Wolf, B.H. [Gesellschaft fuer Schwerionenforschung, Postfach 11 05 52, 64220 Darmstadt (Germany)] [Gesellschaft fuer Schwerionenforschung, Postfach 11 05 52, 64220 Darmstadt (Germany)

1996-03-01

244

Interstitial gas effect on vibrated granular columns  

NASA Astrophysics Data System (ADS)

Vibrated granular materials have been intensively used to investigate particle segregation, convection, and heaping. We report on the behavior of a column of heavy grains bouncing on an oscillating solid surface. Measurements indicate that, for weak effects of the interstitial gas, the temporal variations of the pressure at the base of the column are satisfactorily described by considering that the column, despite the observed dilation, behaves like a porous solid. In addition, direct observation of the column dynamics shows that the grains of the upper and lower surfaces are in free fall in the gravitational field and that the dilation is due to a small delay between their takeoff times.

Pastenes, Javier C.; Géminard, Jean-Christophe; Melo, Francisco

2014-06-01

245

COMPARATIVE YIELDS OF MUTAGENS FROM CIGARETTE SMOKERS' URINE OBTAINED BY USING SOLID-PHASE EXTRACTION TECHNIQUES  

EPA Science Inventory

Urine from cigarette smokers was prepared for mutagenicity testing by extracting mutagens with solid phase extraction columns. ommercially available prepacked bonded silicas (cotadecyl, cyclohexyl, cyanopropyl) were compared for their efficiency and specificity in concentration o...

246

Ion mobility based on column leaching of South African gold tailings dam with chemometric evaluation.  

PubMed

New column leaching experiments were designed and used as an alternative rapid screening approach to element mobility assessment. In these experiments, field-moist material was treated with an extracting solution to assess the effects of acidification on element mobility in mine tailings. The main advantage of this version of column leaching experiments with partitioned segments is that they give quick information on current element mobility in conditions closely simulating field conditions to compare with common unrepresentative air-dried, sieved samples used for column leaching experiments. Layers from the tailings dump material were sampled and packed into columns. The design of columns allows extracting leachates from each layer. The extracting solutions used were natural (pH 6.8) and acidified (pH 4.2) rainwater. Metals and anions were determined in the leachates. The concentrations of metals (Ca, Mg, Fe, Mn, Al, Cr, Ni, Co, Zn, and Cu) in sample leachates were determined using ICP OES. The most important anions (NO3-, Cl-, and SO4(2)-) were determined using the closed system izotacophoresis ITP analyser. The chemical analytical data from tailings leaching and physico-chemical data from field measurements (including pH, conductivity, redox potential, temperature) were used for chemometric evaluation of element mobility. Principal factor analysis (PFA) was used to evaluate ions mobility from different layers of tailings dump arising from varied pH and redox conditions. It was found that the results from the partitioned column leaching illustrate much better complex processes of metals mobility from tailings dump than the total column. The chemometric data analysis (PFA) proofed the differences in the various layers leachability that are arising from physico-chemical processes due to chemical composition of tailings dump deposit. PMID:15109878

Cukrowska, Ewa M; Govender, Koovila; Viljoen, Morris

2004-07-01

247

Earth Pulse  

NSDL National Science Digital Library

Earth Pulse is the National Geographic site for conservation. It features a set of links to National Geographic sites with a variety of conservation themes such as oceans, climate, energy, fresh water, and others. Many of these pages feature interactive tours or videos. Virtual Worlds is a set of interactive tours of various environments, from the rain forest at night to a new urbanist neighborhood. There is also a collection of Sights and Sounds interactive pages on a variety of ecosystems, in which users can click on a map and see information on wildlife that inhabits the selected region. There are also links to news articles and online expeditions in which users can follow actual expeditions as they were conducted by explorers-in-residence.

2007-12-12

248

Surface-initiated molecularly imprinted polymeric column: In situ synthesis and application for semi-preparative separation by high performance liquid chromatography.  

PubMed

In this work, we prepared a monolithic and surface initiated molecularly imprinted polymeric (MIP) column for HPLC and explored its application for template separation from plant extract. The silica beads (40-60 ?m) were coupled with initiator on the surface and then packed in to a stainless steel HPLC column. The pre-polymerization mixture (the template, functional monomer and crosslinker were emodin, acrylamide and divinylbenzene, respectively) was injected into the column and polymerized by thermal initiation. The prepared MIP column exhibited excellent retention capability and large imprinted factor for template (the retention time and imprinted factor for emodin on MIP column were 16.26 min and 7.21, respectively). Moreover, the emodin-molecularly imprinted polymeric column could be applied to separate emodin from alcohol extract of Rheum palmatum L. at semi-preparative scale and 1.2 mg of emodin was obtained in 4 h. PMID:21982996

Gu, Jiangyong; Zhang, Hu; Yuan, Gu; Chen, Lirong; Xu, Xiaojie

2011-11-11

249

Building a Winogradsky Column Video Demonstration  

NSDL National Science Digital Library

This five-minute Quick Time video demonstrates how to build a Winogradsky Column. The video is published by NASA Quest and can be used as a teaching supplement to classroom activities including the Winogradsky Column. This video requires Quick Time player to view, which can be downloaded on site.

Daniella Scalice

250

Results from the Winogradsky Column Study  

NSDL National Science Digital Library

This web page features research results from a student project involving Winogradsky Columns constructed using sandy sediment and water collected from an estuary in Massachusetts. The page includes high-resolution images of the columns and profiles of hydrogen sulfide and methane versus depth.

Science, Semester I.; Laboratory, Marine B.

251

Circulation in gas-slurry column reactors  

SciTech Connect

Circulation in bubble columns, such as those used in fischer-tropsch synthesis, detracts from their performance in that gas is carried on average more rapidly through the column, and the residence time distribution of the gas in the column is widened. Both of these factors influence mass-transfer operations in bubble columns. Circulation prediction and measurement has been undertaken using probes, one-dimensional models, laser Doppler velocimetry, and numerical modeling. Local void fraction was measured using resistance probes and a newly developed approach to determining air/water threshold voltage for the probe. A tall column of eight inch diameter was constructed of Plexiglas and the distributor plate was manufactured to distribute air evenly through the base of the column. Data were gathered throughout the volume at three different gas throughputs. Bubble velocities proved difficult to measure using twin probes with cross-correlation because of radial bubble movement. A series of three-dimensional mean and RMS bubble and liquid velocity measurements were also obtained for a turbulent flow in a laboratory model of a bubble column. These measurements have been made using a three-component laser Doppler velocimeter (LDV), to determine velocity distributions non-intrusively. Finally, the gas-liquid flow inside a vertically situated circular isothermal column reactor was simulated numerically. 74 refs., 170 figs., 5 tabs.

Clark, N.; Kuhlman, J.; Celik, I.; Gross, R.; Nebiolo, E.; Wang, Yi-Zun.

1990-08-15

252

Pharmacia Spin Column Protocol Leslie Vosshall  

E-print Network

Probequant G25 oligonucleotides 100 ul All sizes Probequant G50 DNA 50 ul Microspin G50 ABI sequencing 20 ul of column at perforation. 3. Loosen lid ½ turn and place column into a clean microcentrifuge tube. 4. Spin microcentrifuge tube. 7. Load sample. Be sure to dispense into the resin bed, not around the sides of the tube. 8

253

Counter-current carbon dioxide extraction of soy skim  

Technology Transfer Automated Retrieval System (TEKTRAN)

The use of carbon dioxide in a counter-current fractionation column was investigated as a means to remove residual fat from soy skim after enzyme-assisted aqueous extraction of soybeans. The stainless steel column was 1.2 meters long with an internal diameter of 1.75 cm and filled protruded stainles...

254

How to Calculate Molecular Column Density  

E-print Network

The calculation of the molecular column density from molecular spectral (rotational or ro-vibrational) transition measurements is one of the most basic quantities derived from molecular spectroscopy. Starting from first principles where we describe the basic physics behind the radiative and collisional excitation of molecules and the radiative transfer of their emission, we derive a general expression for the molecular column density. As the calculation of the molecular column density involves a knowledge of the molecular energy level degeneracies, rotational partition functions, dipole moment matrix elements, and line strengths, we include generalized derivations of these molecule-specific quantities. Given that approximations to the column density equation are often useful, we explore the optically thin, optically thick, and low-frequency limits to our derived general molecular column density relation. We also evaluate the limitations of the common assumption that the molecular excitation temperature is con...

Mangum, Jeffrey G

2015-01-01

255

Determination of ochratoxin A at the ppt level in human blood, serum, milk and some foodstuffs by high-performance liquid chromatography with enhanced fluorescence detection and immunoaffinity column cleanup: methodology and Swiss data  

Microsoft Academic Search

An improved specific analytical method for ochratoxin A (OA) is presented, combining HPLC separation with enhanced fluorescence detection by post-column addition of ammonia. Commercial immunoaffinity columns (Biocode) were for the first time applied to the cleanup of extracts of body fluids; they could be used up to 20 times for blood serum. The extraction efficiency of OA from human serum

Bernhard Zimmerli; Rudolf Dick

1995-01-01

256

Limit for pulse compression by pulse splitting  

Microsoft Academic Search

We have detected a fundamental pulse-compression limit for high-nonlinear fibers in the normal dispersion regime near the\\u000a zero-dispersion wavelength. The desired generation of a broadband continuum by self-phase modulation is limited by already\\u000a small amounts of third-order dispersion (TOD), which results in pulse splitting above a critical pulse power. We investigate\\u000a the critical fiber length in dependence on pulse- and

Ayhan Demircan; Uwe Bandelow

2006-01-01

257

In situ extractive fermentation of acetone and butanol  

Microsoft Academic Search

The productivity of the acetone-butanol fermentation was increased by continuously removing acetone and butanol from the fermentation broth during fed-batch culture. Whole broth containing viable cells of Clostridium acetobutylicum was cycled to a Karr reciprocating plate extraction column in which acetone and butanol were extracted into oleyl alcohol flowing counter-currently through the column. By continuously removing these toxic metabolites from

S. R. Roffler; H. W. Blanch; C. R. Wilke

1988-01-01

258

Phase-coherent light pulses for atom optics and interferometry.  

PubMed

We have developed a novel source for the generation of powerful phase-coherent light pulses. Our setup uses an acousto-optic modulator (AOM) inside an external high-finesse resonator. By applying a short rf pulse to the AOM, we dump the cavity and extract a large part of the stored and enhanced power within a short optical pulse and with a controllable optical phase. In preliminary experiments we reached 100 W of peak power in a 15-ns optical pulse. The mutual phase coherence of successive light pulses is demonstrated with a molecular iodine interferometer experiment in a cell. PMID:18188346

Heupel, T; Weitz, M; Hänsch, T W

1997-11-15

259

Analysis of extractable organic compounds in water by gas chromatography mass spectrometry: applications to surface water.  

PubMed

Contamination of water by organic pollutants is a common environmental problem. Over a period of 1 year, the surface water of a canal network (Languedoc-Roussillon area, France) was analysed in order to identify organic compounds and to monitor its quality. Pollutants were extracted from 19 l of raw water using methylene chloride in a continuous countercurrent liquid-liquid extractor with a pulsed column. The extraction was performed at a pH above 11 and again at a pH below 2 according to U.S. Environmental Protection Agency method 625. The extract was analysed by gas chromatography/mass spectrometry, using two ionization techniques, namely electron ionization and chemical ionization. Mass spectra obtained by electron ionization were compared with those in a database (NIST). Some natural compounds and micropollutants were identified. Their structures were confirmed by chemical ionization (methane). One hundred and ten substances, making up the broad spectrum of extractable compounds in the surface water studied, were found by this method at a nanogram per litre concentration level. Among them, 13 are priority pollutants. These specific pollutants were qualified. PMID:18966498

Deroux, J M; Gonzalez, C; Le Cloirec, P; Kovacsik, G

1996-03-01

260

Investigating Bacteria with the Winogradsky Column  

NSDL National Science Digital Library

This is an instructor's guide to teaching about biodiversity in the microbial world. This activity encourages students to investigate bacteria using a Winogradsky Column. Students can create a unique environment with slight variations on the recipe; and soon have an inquiry project that could easily occupy the entire year. With the simple extensions given, teachers can isolate and grow a number of the species found in the column and extend this column to a number of examples in the real world showing the relevance of this complex yet deceptively simple lab.

Rogan, Brian

2010-02-18

261

Flutter of cantilevered column under rocket thrust  

NASA Astrophysics Data System (ADS)

This paper describes an experimental investigation on the flutter of visco-elastic cantilevers subjected to a tangential follower force. The force was produced by the direct installation of a real solid rocket motor to the tip end of the cantilevered columns. The columns lost their stability by flutter. The results were compared with theoretical flutter predictions made by accounting for an internal damping of the test columns, as well as the mass and size of the installed rocket motor. The introduction of the concept of instability in a finite time interval is of vital importance in predicting the experimental flutter force.

Sugiyama, Yoshihiko; Katayama, Kazuo; Kinoi, Sigeru

1995-01-01

262

Long pulse production from short pulses  

DOEpatents

A method of producing a long output pulse from a short pump pulse is disclosed, using an elongated amplified fiber having a doped core that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding. A seed beam of the longer wavelength is injected into the core at one end of the fiber and a pump pulse of the shorter wavelength is injected into the cladding at the other end of the fiber. The counter-propagating seed beam and pump pulse will produce an amplified output pulse having a time duration equal to twice the transit time of the pump pulse through the fiber plus the length of the pump pulse. 3 figs.

Toeppen, J.S.

1994-08-02

263

Long pulse production from short pulses  

DOEpatents

A method of producing a long output pulse (SA) from a short pump pulse (P), using an elongated amplified fiber (11) having a doped core (12) that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding 13. A seed beam (S) of the longer wavelength is injected into the core (12) at one end of the fiber (11) and a pump pulse (P) of the shorter wavelength is injected into the cladding (13) at the other end of the fiber (11). The counter-propagating seed beam (S) and pump pulse (P) will produce an amplified output pulse (SA) having a time duration equal to twice the transit time of the pump pulse (P) through the fiber (11) plus the length of the pump pulse (P).

Toeppen, John S. (Livermore, CA)

1994-01-01

264

Plastic Hinging Behavior of Reinforced Concrete Bridge Columns  

E-print Network

The location of inelastic deformations in reinforced concrete bridge columns has been examined to simulate the nonlinear response of bridge columns and estimate the ultimate displacement capacity. In bridge columns, these nonlinear deformations...

Firat Alemdar, Zeynep

2010-04-27

265

STUDENT PULSE Spring 2013  

E-print Network

Research (air.sfsu.edu) March 2013 #12;SF State Student Pulse Survey, Spring 2013 Page 1 Table of ContentsSF STATE STUDENT PULSE SURVEY Spring 2013 Academic Planning and Development Academic Institutional State Student Pulse Survey, Spring 2013 Page 2 SF STATE ­ Student Pulse Survey Executive Summary

266

AVIRIS Spectrometer Maps Total Water Vapor Column  

NASA Technical Reports Server (NTRS)

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) processes maps of vertical-column abundances of water vapor in atmosphere with good precision and spatial resolution. Maps provide information for meteorology, climatology, and agriculture.

Conel, James E.; Green, Robert O.; Carrere, Veronique; Margolis, Jack S.; Alley, Ronald E.; Vane, Gregg A.; Bruegge, Carol J.; Gary, Bruce L.

1992-01-01

267

A Versatile, Automatic Chromatographic Column Packing Device  

ERIC Educational Resources Information Center

Describes an inexpensive apparatus for packing liquid and gas chromatographic columns of high efficiency. Consists of stainless steel support struts, an Automat Getriebmotor, and an associated three-pulley system capable of 10, 30, and 300 rpm. (MLH)

Barry, Eugene F.; And Others

1977-01-01

268

Monolithic and core-shell columns in comprehensive two-dimensional HPLC: a review.  

PubMed

The crucial point affecting the separation time in comprehensive two-dimensional liquid chromatography is the performance of the column used in the second dimension, which should allow highly efficient fast chromatographic separations in the short time available for the analysis of fractions transferred from the first to the second dimension (often 1 min or less). This can be accomplished on short columns packed with sub-2-?m particles, at the cost of very high operation pressure. Core-shell or silica monolithic columns have better permeability, and their use in the second dimension of comprehensive two-dimensional liquid chromatography with conventional liquid chromatography instrumentation is continuously increasing. Monolithic columns based on organic polymer matrices offer a wide selection of stationary phase chemistries, including new hydrophilic interaction liquid chromatography materials, which can be used in the design of novel two-dimensional separations. Some organic polymer monolithic materials offer a dual retention mechanism (reversed-phase hydrophilic interaction liquid chromatography), so a single column can be used in alternating runs for highly orthogonal off-line two-dimensional and even three-dimensional separations. In the present work, the properties of core-shell and silica gel monolithic columns are briefly summarized and their applications in two-dimensional separations of peptides, proteins, oligomer surfactants, fats and oils, carotenoids, phenolic and flavone compounds in plant extracts, food, and beverages are reviewed. PMID:25326881

Jandera, Pavel; Hájek, Tomáš; Sta?ková, Magda

2015-01-01

269

The Impact Biomechanics of Spinal Column Injuries  

Microsoft Academic Search

The vertebral column is the central bony pillar of the body and serves to protect the spinal cord from injury. Vertebrae show\\u000a regional differences but they all possess a common pattern. Analysis of the biomechanics of individual components of the spine\\u000a allows one to predict how the spinal column behaves during impact. Although many forces and moments in different directions

M. J. Shelly; A. R. Poynton

270

Divided Wall Column Without the Wall  

E-print Network

the partitions. Consequently, operating range is very limited. An additional thermodynamic deficiency inherent in the PETLYUK system lies within the vapor mixing and liquid mixing zones as further explained below. Let us focus on the vapor... Balanced Fully Thermally Coupled system (HBFTC system), is a column equipped with one reboiler 100 and one condenser 200. Further, the column is divided into four operating zones, in ascending elevation as follows: ?? A stripping zone, zone B, 1...

Tung, P.

2004-01-01

271

Pulse Consumption, Satiety, and Weight Management1  

PubMed Central

The prevalence of obesity has reached epidemic proportions, making finding effective solutions to reduce obesity a public health priority. One part of the solution could be for individuals to increase consumption of nonoilseed pulses (dry beans, peas, chickpeas, and lentils), because they have nutritional attributes thought to benefit weight control, including slowly digestible carbohydrates, high fiber and protein contents, and moderate energy density. Observational studies consistently show an inverse relationship between pulse consumption and BMI or risk for obesity, but many do not control for potentially confounding dietary and other lifestyle factors. Short-term (?1 d) experimental studies using meals controlled for energy, but not those controlled for available carbohydrate, show that pulse consumption increases satiety over 2–4 h, suggesting that at least part of the effect of pulses on satiety is mediated by available carbohydrate amount or composition. Randomized controlled trials generally support a beneficial effect of pulses on weight loss when pulse consumption is coupled with energy restriction, but not without energy restriction. However, few randomized trials have been conducted and most were short term (3–8 wk for whole pulses and 4–12 wk for pulse extracts). Overall, there is some indication of a beneficial effect of pulses on short-term satiety and weight loss during intentional energy restriction, but more studies are needed in this area, particularly those that are longer term (?1 y), investigate the optimal amount of pulses to consume for weight control, and include behavioral elements to help overcome barriers to pulse consumption. PMID:22043448

McCrory, Megan A.; Hamaker, Bruce R.; Lovejoy, Jennifer C.; Eichelsdoerfer, Petra E.

2010-01-01

272

Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column  

NASA Technical Reports Server (NTRS)

RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better detection via good peak separation with a longer run time is a better asset than moderate peak separation with a shorter run time. Even given that RESOLVE is highly interested in water and that mission timeline is of significant importance given the short seven-to-ten-day mission timeline, worse detection with an 8m column may lead to overlooking other substances existing on the moon that could advance planetary science. Thus, I recommend the 20m column. However, if mission timeline and water separation are deemed the highest priority, the 8m column should be selected due to its ability to separate water within a shorter run time than the 20m column.

Huz, Kateryna

2014-01-01

273

Interpretation of the lime column penetration test  

NASA Astrophysics Data System (ADS)

Dry soil mix (DSM) columns are used to reduce the settlement and to improve the stability of embankments constructed on soft clays. During construction the shear strength of the columns needs to be confirmed for compliance with technical assumptions. A specialized blade shaped penetrometer known as the lime column probe, has been developed for testing DSM columns. This test can be carried out as a pull out resistance test (PORT) or a push in resistance test (PIRT). The test is considered to be more representative of average column shear strength than methods that test only a limited area of the column. Both PORT and PIRT tests require empirical correlations of measured resistance to an absolute measure of shear strength, in a similar manner to the cone penetration test. In this paper, finite element method is used to assess the probe factor, N, for the PORT test. Due to the large soil deformations around the probe, an Arbitrary Lagrangian Eulerian (ALE) based finite element formulation has been used. Variation of N with rigidity index and the friction at the probe-soil interface are investigated to establish a range for the probe factor.

Liyanapathirana, D. S.; Kelly, R. B.

2010-06-01

274

Magnetohydrodynamic Augmentation of Pulse Detonation Engines  

Microsoft Academic Search

Pulse detonation engines (PDEs) are the focus of increasing attention due to their potentially superior performance over constant pressure engines. Yet due to its unsteady chamber pressure, the PDE system will either be over- or under-expanded for the majority of the cycle, with energy being used without maximum gain. Magnetohydrodynamic (MHD) augmentation offers the opportunity to extract energy and apply

Christopher Zeineh; Lord Cole; Ann Karagozian

2010-01-01

275

An improved method for IEDF determination in pulsed plasmas and its application to the pulsed dc magnetron  

Microsoft Academic Search

In this paper we demonstrate an improved technique for obtaining time-resolved ion energy distribution functions (IEDFs) in pulsed plasma discharges using a commercial quadrupole mass energy analyser. The method involves extracting ions from the plasma at selected times during the pulse cycle through the application of a synchronized electrical bias on a grid assembly built in the barrel of the

S. A. Voronin; G. C. B. Clarke; M. Cada; P. J. Kelly; J. W. Bradley

2007-01-01

276

Pulsed pyroelectric crystal-powered gamma source  

SciTech Connect

A compact pulsed gamma generator is being developed to replace radiological sources used in commercial, industrial and medical applications. Mono-energetic gammas are produced in the 0.4 - 1.0 MeV energy range using nuclear reactions such as {sup 9}Be(d,n{gamma}){sup 10}B. The gamma generator employs an RF-driven inductively coupled plasma ion source to produce deuterium ion current densities up to 2 mA/mm{sup 2} and ampere-level current pulses can be attained by utilizing an array extraction grid. The extracted deuterium ions are accelerated to approximately 300 keV via a compact stacked pyroelectric crystal system and then bombard the beryllium target to generate gammas. The resulting microsecond pulse of gammas is equivalent to a radiological source with curie-level activity.

Chen, A. X.; Antolak, A. J.; Leung, K.-N.; Raber, T. N.; Morse, D. H. [Sandia National Laboratories, Livermore, CA 94550 (United States)

2013-04-19

277

The characteristics of open-tubular capillary electrochromatography columns with series/mixed stationary phases constructed with magnetic nanoparticle coating.  

PubMed

Novel open-tubular capillary electrochromatography (OT-CEC) systems with core/shell magnetic nanoparticles modified by amino or C18 groups as stationary phase were constructed by immobilizing nanoparticles in the capillary with permanent magnets. Influence of preparation method of OT-CEC column with series stationary phases (continuous two-dimension) on column performance and effect of dispersant on capability of OT-CEC column prepared by stationary phases with mixed functionalities (mixed stationary phases) were investigated in details to achieve stable preparation. Organic acids were used to evaluate the OT-CEC systems, and the relative column efficiency of salicylic acid was 420,000 plates/m for series stationary phases, while that of benzoic acid reached 480,000 plates/m for mixed stationary phases. The excellent within-column and between-column repeatability (n=5) testified with the RSDs of retention time were less than 0.44% and 10.20% for series stationary phases and 1.65% and 4.29% for mixed stationary phases. The two OT-CEC systems were further applied to separation of the aqueous extract of Rhizoma gastrodiae. Comparing with normal OT capillary column, the new systems show extra high column efficiency due to large surface areas of nanoparticles and multiple separation mechanisms, and they have great potential in the method development for the analysis of complicated samples. PMID:23597906

Zhu, Yaxian; Zhang, Lingyi; Qian, Junhong; Zhang, Weibing

2013-01-30

278

Third Sound Pulse Collisions  

NASA Astrophysics Data System (ADS)

We report measurements of third sound pulses in head-on collisions (K. S. Ketola, S. Wang, and R. B. Hallock, Physica B 194--196), 651 (1994). as a function of superfluid ^4He film thickness, pulse amplitude and pulse width for temperatures near 1.5 K. The substrate is a borosilicate glass slide with two Ag thermal drivers and an Al transition edge bolometer located halfway between the drivers. By generating one heating pulse from each driver separated by a selectable time delay, we can measure the profile of a collision with the bolometer, or we can cause the collision to occur between the bolometer and one of the drivers and observe the scattered third sound pulse. We explore collisions for a variety of conditions and show how the pulse interactions depend on the drive amplitudes. Measurements of single cooling pulses, cooling pulse collisions and heating pulses in an applied steady film flow will also be presented.

Hallock, R. B.; Lilly, M. P.

1996-03-01

279

On the Origin of the High Column Density Turnover in the H I Column Density Distribution  

NASA Astrophysics Data System (ADS)

We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N H I ? 1021 cm-2, which is present at both z = 0 and z ? 3, and a lack of systems above N H I ? 1022 cm-2 at z = 0. Using observations of the column density distribution, we argue that the H I-H2 transition does not cause the turnover at N H I ? 1021 cm-2 but can plausibly explain the turnover at N H I >~ 1022 cm-2. We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Ly? column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ~ kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.

Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

2012-12-01

280

Laser pulse stacking method  

DOEpatents

A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

Moses, E.I.

1992-12-01

281

Nerve-pulse interactions  

SciTech Connect

Some recent experimental and theoretical results on mechanisms through which individual nerve pulses can interact are reviewed. Three modes of interactions are considered: (1) interaction of pulses as they travel along a single fiber which leads to velocity dispersion; (2) propagation of pairs of pulses through a branching region leading to quantum pulse code transformations; and (3) interaction of pulses on parallel fibers through which they may form a pulse assembly. This notion is analogous to Hebb's concept of a cell assembly, but on a lower level of the neural hierarchy.

Scott, A.C.

1982-01-01

282

Counterflow isotachophoresis in a monolithic column.  

PubMed

This study describes stationary counterflow isotachophoresis (ITP) in a poly(acrylamide-co-N,N'-methylenebisacrylamide) monolithic column as a means for improving ITP processing capacity and reducing dispersion. The flow profile in the monolith was predicted using COMSOL's Brinkman Equation application mode, which revealed that the flow profile was mainly determined by monolith permeability. As monolith permeability decreases, the flow profile changes from a parabolic shape to a plug shape. An experimental monolithic column was prepared in a fused-silica capillary using an ultraviolet-initiated polymerization method. A monolithic column made from 8% (wt.) monomer was chosen for the stationary counterflow ITP experiments. Counterflow ITP in the monolithic column showed undistorted analyte zones with significantly reduced dispersion compared to the severe dispersion observed in an open capillary. Particularly, for r-phycoerythrin focused by counterflow ITP, its zone width in the monolithic column was only one-third that observed in an open capillary. These experiments demonstrate that stationary counterflow ITP in monoliths can be a robust and practical electrofocusing method. PMID:24935025

Liu, Bingwen; Cong, Yongzheng; Ivory, Cornelius F

2014-09-01

283

Column bioleaching of uranium embedded in granite porphyry by a mesophilic acidophilic consortium.  

PubMed

A mesophilic acidophilic consortium was enriched from acid mine drainage samples collected from several uranium mines in China. The performance of the consortium in column bioleaching of low-grade uranium embedded in granite porphyry was investigated. The influences of several chemical parameters on uranium extraction in column reactor were also investigated. A uranium recovery of 96.82% was achieved in 97 days column leaching process including 33 days acid pre-leaching stage and 64 days bioleaching stage. It was reflected that indirect leaching mechanism took precedence over direct. Furthermore, the bacterial community structure was analyzed by using Amplified Ribosomal DNA Restriction Analysis. The results showed that microorganisms on the residual surface were more diverse than that in the solution. Acidithiobacillus ferrooxidans was the dominant species in the solution and Leptospirillum ferriphilum on the residual surface. PMID:21316943

Qiu, Guanzhou; Li, Qian; Yu, Runlan; Sun, Zhanxue; Liu, Yajie; Chen, Miao; Yin, Huaqun; Zhang, Yage; Liang, Yili; Xu, Lingling; Sun, Limin; Liu, Xueduan

2011-04-01

284

Chromatographic separation of arsenic species with pentafluorophenyl column and application to rice.  

PubMed

Arsenic species, including arsenous acid, arsenic acid, methylarsonic acid, and dimethylarsinic acid, were determined using HPLC-ICPMS. The species were separated with a Discovery HS F5 column and a simple, volatile, and isocratic mobile phase of 0.1% (v/v) formic acid and 1% (v/v) methanol. The Discovery HS F5 column with a pentafluorophenyl (PFP) stationary phase gave sharp peaks and full separation of the arsenic species in 5min, and other PFP columns showed lower performance. This separation method was applied to arsenic species analysis in rice. The extraction of arsenic from rice samples was performed using 0.15M nitric acid. The methodology was validated by use of certified reference materials, NMIJ CRM 7503-a and NIST SRM 1568a, and extremely low arsenic rice samples as blank samples. PMID:24947890

Baba, Koji; Arao, Tomohito; Yamaguchi, Noriko; Watanabe, Eiki; Eun, Heesoo; Ishizaka, Masumi

2014-08-01

285

Bioretention column studies of phosphorus removal from urban stormwater runoff.  

PubMed

This study investigated the effectiveness of bioretention as a stormwater management practice using repetitive bioretention columns for phosphorus removal. Bioretention media, with a higher short-term phosphorus sorption capacity, retained more phosphorus from infiltrating runoff after 3 mg/L phosphorus loading. A surface mulch layer prevented clogging after repetitive total suspended solids input. Evidence suggests that long-term phosphorus reactions will regenerate active short-term phosphorus adsorption sites. A high hydraulic conductivity media overlaying one with low hydraulic conductivity resulted in a higher runoff infiltration rate, from 0.51 to 0.16 cm/min at a fixed 15-cm head, and was more efficient in phosphorus removal (85% mass removal) than a profile with low conductivity media over high (63% mass removal). Media extractions suggest that most of the retained phosphorus in the media layers is available for vegetative uptake and that environmental risk thresholds were not exceeded. PMID:17370843

Hsieh, Chi-hsu; Davis, Allen P; Needelman, Brian A

2007-02-01

286

Thermal Imaging of the Superficial Temporal Artery: An Arterial Pulse Recovery Model  

E-print Network

. A multresolution wavelet-based signal analy- sis approach is used to extract the arterial pulse waveform, which limitation was the validation of the results. The reported arterial pulse wave- forms agreed with the groundThermal Imaging of the Superficial Temporal Artery: An Arterial Pulse Recovery Model Sergey Y

Farag, Aly A.

287

Monitoring respiration rate in PACU patients using the plethysmogram from a pulse oximeter Suzanne M. Wendelken*  

E-print Network

Monitoring respiration rate in PACU patients using the plethysmogram from a pulse oximeter Suzanne), few have their respiration rate monitored. The goal of our study is to develop algorithms that reliably extract the respiration rate from a standard pulse oximeter signal. The pulse oximeter

Linder, Stephen

288

Selective analysis of secondary amino acids in gelatin using pulsed electrochemical detection.  

PubMed

A method was developed for selective analysis of the secondary amino acids proline and 4-hydroxyproline from gelatin hydrolysates using anion-exchange high-performance liquid chromatography followed by integrated pulsed amperometric detection (HPLC-IPAD). An extraction scheme was implemented prior to HPLC-IPAD analysis to isolate the secondary amino acids by the removal of primary amino acids through derivatization with o-phthalaldehyde followed by solid-phase extraction with C18 packed columns. The use of the IPAD technique eliminated the need for a second derivatization step to detect secondary amino acids. The removal of interfering primary amino acids prior to chromatographic analysis allowed the use of isocratic mobile-phase conditions to achieve effective and efficient separation of the amino acids. This led to a more precise and accurate quantitation of their content in gelatin hydrolysates. Detection limits approach 10 parts per billion ( approximately 2 pmol/injection) with a chromatographic analysis time under 8 min. The ratios of secondary amino acids, in addition to their abundances, were used to distinguish gelatin manufactured from bovine, porcine, and fish raw material sources. PMID:17683165

Russell, Jason D; Dolphin, John M; Koppang, Miles D

2007-09-01

289

PCB fluxes from the sediment to the water column following resuspension A column experiment  

E-print Network

, have been specially designed to study PCB behavior during sediment resuspension, settlingPCB fluxes from the sediment to the water column following resuspension ­ A column experiment was systematically due to significant levels of PCB-DL and PCDD/F in fish tissue. New campaigns of characterization

Paris-Sud XI, Université de

290

SNS EXTRACTION FAST KICKER SYSTEM DEVELOPMENT.  

SciTech Connect

The SNS Extraction Fast Kicker System is a very high power, high repetition rate pulsed power system. It was design and developed at Brookhaven National Laboratory. This system will consist of fourteen identical high voltage, high current modulators, and their auxiliary control and charging systems. The modulators will drive fourteen extraction magnet sections located inside of the SNS accumulator ring. The required kicker field rise time is 200 ns, a pulse flattop of 700 ns, a pulse repetition rate of 60 pulse-per-second. A 2500 Ampere per modulator output is required to reach the extraction kicker magnetic field strength. This design features a Blumlein Pulse-Forming-Network based topology, a low beam impedance termination, a fast current switching thyratron, and low inductance capacitor banks. It has a maximum charging voltage of 50kV, an open circuit output of 100kV, and a designed maximum pulsed current output of 4kA per modulator. The overall system output will be multiple GVA with 60 Pulse-per-second repetition rate. A prototype modulator has been successfully built and tested well above the SNS requirement. The modulator system production is in progress.

ZHANG,W.; SANDBERG,J.; LAMBIASE,R.; LEE,Y.Y.; LOCKEY,R.; MI,J.; NEHRING,T.; PAI,C.; TSOUPAS,N.; TUOZZOLO,J.; WARBURTON,D.; WEI,J.; RUST,K.; CUTLER,R.

2003-06-15

291

Extraction, Purification, and Spectroscopic Characterization of a Mixture of Capsaicinoids  

ERIC Educational Resources Information Center

This laboratory experiment provides a safe and effective way to instruct undergraduate organic chemistry students about natural-product extraction, purification, and NMR spectroscopic characterization. On the first day, students extract dried habanero peppers with toluene, perform a pipet silica gel column to separate carotenoids from…

Wagner, Carl E.; Cahill, Thomas M.; Marshall, Pamela A.

2011-01-01

292

CHARACTERIZATION OF SHALLOT, AN ANTIMICROBIAL EXTRACT OF ALLIUM ASCALONICUM  

Microsoft Academic Search

Objective: The objective of this study was characterization of antimicrobial extract of shallot in terms of its stability at different pH, Heat, enzymes and detergents and also determination of its MIC and shelf life. Methodology: Active fraction was determined by column chromatography and agar diffusion test. The amount of carbohydrate and protein in different forms of shallot extract were estimated.

Mansour Amin; Effat Abasi Montazeri; Mohammad Ali Mashhadizadeh; Ahmad Farajzadeh Sheikh

293

Pulse to pulse klystron diagnosis system  

SciTech Connect

This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 ..mu..s. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations.

Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

1981-03-01

294

[Packed glass capillary column with multi-cores].  

PubMed

The paper describes the preparation of the columns with multi-cores and their plate heights, optimum gas velocity, minimum plate heights (HETP) and corresponding pressure drop (deltaP=Pi-Po) were measured. It is found that HETP increases as core number increase, but column pressure drop (deltaP) decrease with increase of core number. The conclusion is: 1. The column with multi-cores have a better permeability than the conventional packed capillary column. Although its column efficiency is lower than that of the conventional one when packed particles is in the same column size, the comprehensive properties (N/deltaP) are evidently superior than the conventional capillary column. 2. The pressure drop decreasesas the number and diameter of the core in packed capillary column increase. 3. When packed column particle size gets smaller, column efficiency gets higher, but the particle inlay bacomes difficult. The existence of the cores will make the column efficiency get some loss, but it can improve the column permeability and the inlaid geomery. 4. In considering pressure drop, HETP and the particle inlaid condition in column fabrication as a whole, the optimum column type is the packed capillary column with three cores. 5. Ideal column size is: deltad=1-1. 5dp,d=1-2dp,n> or =3, dp=140-250 mesh. PMID:15739425

Liu, X; Yang, H; Lu, W

1997-01-01

295

Non-planar microfabricated gas chromatography column  

DOEpatents

A non-planar microfabricated gas chromatography column comprises a planar substrate having a plurality of through holes, a top lid and a bottom lid bonded to opposite surfaces of the planar substrate, and inlet and outlet ports for injection of a sample gas and elution of separated analytes. A plurality of such planar substrates can be aligned and stacked to provide a longer column length having a small footprint. Furthermore, two or more separate channels can enable multi-channel or multi-dimensional gas chromatography. The through holes preferably have a circular cross section and can be coated with a stationary phase material or packed with a porous packing material. Importantly, uniform stationary phase coatings can be obtained and band broadening can be minimized with the circular channels. A heating or cooling element can be disposed on at least one of the lids to enable temperature programming of the column.

Lewis, Patrick R. (Albuquerque, NM); Wheeler, David R. (Albuquerque, NM)

2007-09-25

296

Final Report, Distillation Column Flooding Predictor  

SciTech Connect

The Flooding Predictor is an advanced process control strategy comprising a patented pattern-recognition methodology that identifies pre-flood patterns discovered to precede flooding events in distillation columns. The grantee holds a U.S. patent on the modeling system. The technology was validated at the Separations Research Program, The University of Texas at Austin under a grant from the U. S. Department of Energy, Inventions & Innovation Program. Distillation tower flooding occurs at abnormally high vapor and/or liquid rates. The loss in tray efficiencies is attributed to unusual behavior of liquid inventories inside the column leading to conditions of flooding of the space in between trays with liquid. Depending on the severity of the flood condition, consequences range from off spec products to equipment damage and tower shutdown. This non-intrusive pattern recognition methodology, processes signal data obtained from existing column instrumentation. Once the pattern is identified empirically, it is modeled and coded into the plant's distributed control system. The control system is programmed to briefly "unload" the tower each time the pattern appears. The unloading takes the form of a momentary reduction in column severity, e.g., decrease bottom temperature, reflux or tower throughput. Unloading the tower briefly at the pre-flood state causes long-term column operation to become significantly more stable - allowing an increase in throughput and/or product purity. The technology provides a wide range of value between optimization and flooding. When a distillation column is not running at capacity, it should be run in such a way ("pushed") that optimal product purity is achieved. Additional benefits include low implementation and maintenance costs, and a high level of console operator acceptance. The previous commercial applications experienced 98% uptime over a four-year period. Further, the technology is unique in its ability to distinguish between different flooding mechanisms within the same tower, e.g., liquid and jet flooding.

George E. Dzyacky

2003-05-31

297

Complex osteotomies vertebral column resection and decancellation.  

PubMed

Pedicle subtraction osteotomy (PSO) is nowadays widely used to treat sagittal imbalance. Some complex malalignment cases cannot be treated by a PSO, whereas the imbalance is coronal or mixed or the sagittal imbalance is major and cannot be treated by a single PSO. The aim of this article was to review these complex situations--coronal imbalance, mixed imbalance, two-level PSO, vertebral column resection, and vertebral column decancellation, and to focus on their specificities. It wills also to evoke the utility of navigation in these complex cases. PMID:24831304

Obeid, Ibrahim; Bourghli, Anouar; Boissičre, Louis; Vital, Jean-Marc; Barrey, Cédric

2014-07-01

298

Optical Measurement Technique for Space Column Characterization  

NASA Technical Reports Server (NTRS)

A simple optical technique for the structural characterization of lightweight space columns is presented. The technique is useful for determining the coefficient of thermal expansion during cool down as well as the induced strain during tension and compression testing. The technique is based upon object-to-image plane scaling and does not require any photogrammetric calibrations or computations. Examples of the measurement of the coefficient of thermal expansion are presented for several lightweight space columns. Examples of strain measured during tension and compression testing are presented along with comparisons to results obtained with Linear Variable Differential Transformer (LVDT) position transducers.

Barrows, Danny A.; Watson, Judith J.; Burner, Alpheus W.; Phelps, James E.

2004-01-01

299

Divided-Pulse Lasers  

PubMed Central

We demonstrate the use of coherent division and recombination of the pulse within an ultrafast laser cavity to manage the nonlinear phase accumulation and scale the output pulse energy. We implement the divided-pulse technique in an ytterbium-doped fiber laser and achieve 16-times scaling of the pulse energy, to generate 6 nJ and 1.4 ps solitons in single mode fiber. Potential extensions of this concept are discussed. PMID:24784100

Lamb, Erin S.; Wright, Logan G.; Wise, Frank W.

2014-01-01

300

Constant potential pulse polarography  

USGS Publications Warehouse

The new technique of constant potential pulse polarography, In which all pulses are to be the same potential, is presented theoretically and evaluated experimentally. The response obtained is in the form of a faradaic current wave superimposed on a constant capacitative component. Results obtained with a computer-controlled system exhibit a capillary response current similar to that observed In normal pulse polarography. Calibration curves for Pb obtained using a modified commercial pulse polarographic instrument are in good accord with theoretical predictions.

Christie, J.H.; Jackson, L.L.; Osteryoung, R.A.

1976-01-01

301

Optically pulsed electron accelerator  

DOEpatents

An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

Fraser, John S. (Los Alamos, NM); Sheffield, Richard L. (Los Alamos, NM)

1987-01-01

302

Divided-pulse lasers.  

PubMed

We demonstrate the use of coherent division and recombination of the pulse within an ultrafast laser cavity to manage the nonlinear phase accumulation and scale the output pulse energy. We implement the divided-pulse technique in an ytterbium-doped fiber laser and achieve 16 times scaling of the pulse energy, to generate 6 nJ and 1.4 ps solitons in single-mode fiber. Potential extensions of this concept are discussed. PMID:24784100

Lamb, Erin S; Wright, Logan G; Wise, Frank W

2014-05-01

303

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components.  

DOEpatents

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Egorov, Oleg B. (Richland, WA); O'Hara, Matthew J. (Richland, WA); Grate, Jay W. (West Richland, WA); Chandler, Darrell P. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Bruckner-Lea, Cynthia J. (Richland, WA)

2004-08-24

304

Systems for column-based separations, methods of forming packed columns, and methods of purifying sample components  

DOEpatents

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Egorov, Oleg B. (Richland, WA); O'Hara, Matthew J. (Richland, WA); Grate, Jay W. (West Richland, WA); Chandler, Darrell P. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Bruckner-Lea, Cynthia J. (Richland, WA)

2000-01-01

305

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components  

DOEpatents

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Egorov, Oleg B. (Richland, WA); O'Hara, Matthew J. (Richland, WA); Grate, Jay W. (West Richland, WA); Chandler, Darrell P. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Bruckner-Lea, Cynthia J. (Richland, WA)

2006-02-21

306

Elucidation of Phosphatidylcholine Composition in Krill Oil Extracted from Euphausia superba  

PubMed Central

High performance liquid chromatography-electrospray tandem mass spectrometry was used to elucidate the phospholipids in krill oil extracted from Euphausia superba, an emerging source for human nutritional supplements. The study was carried out in order to map the species of the choline-containing phospholipid classes: phosphatidylcholine and lyso-phosphatidylcholine. In addition, the prevalent phosphatidylcholine class was quantified and the results compared with prior analysis. The qualification was performed with separation on a reverse phase chromatography column, while the quantification was obtained with class separation on a normal phase chromatography column. An Orbitrap system was used for the detection, and pulsed-Q dissociation fragmentation was utilized for the identification of the species. An asymmetrical exclusion list was applied for detection of phospholipid species of lower concentration, significantly improving the number of species observed. A total of 69 choline-containing phospholipids were detected, whereof 60 phosphatidylcholine substances, among others seven with probable omega-3 fatty acids in both sn-1 and sn-2. The phosphatidylcholine concentration was estimated to be 34 ± 5 g/100 g oil (n = 5). These results confirm the complexity of the phospholipid composition of krill oil, and the presence of long chained, heavily unsaturated fatty acids. PMID:20848234

Winther, Bjřrn; Hoem, Nils; Berge, Kjetil

2010-01-01

307

Determination of residues of carbadox and some of its metabolites in swine tissues by high-performance liquid chromatography using on-line pre-column enrichment and post-column derivatization with UV-VIS detection.  

PubMed

A high-performance liquid chromatographic (HPLC) method that uses UV-VIS detection and post-column derivatization with sodium hydroxide was developed for the determination of the growth-promoting antibiotic carbadox and three of its metabolites in swine muscle, liver and kidney tissues. Sample pre-treatment involves extraction with methanol-acetonitrile, purification over an alumina-Florisil column and partition with isooctane. A 2-ml volume of the final aqueous extract is injected into a column-switching HPLC system; detection is performed at 420 nm. The limits of determination are in the range 1-5 micrograms/kg. Preliminary experiments show a good precision with mean recoveries of 81-87% and a coefficient of variation of 4-10%. The method is highly selective and can be used in routine monitoring programmes. PMID:3243862

Aerts, M M; Beek, W M; Keukens, H J; Brinkman, U A

1988-12-01

308

?-Linolenic acid purification from seed oil sources by argentated silica gel chromatography column  

Microsoft Academic Search

The polyunsaturated fatty acid ?-linolenic acid (GLA,18:3?6), which has several pharmaceutical properties, has been purified from the seed oil of three plant species, Anchusa azurea, Scrophularia sciophila and Echium fastuosum. The process consists of four main steps, (i) simultaneous extraction and saponification of the seeds; (ii) urea fractionation method; (iii) urea-concentrate methylation; (iv) argentated silica gel column chromatography of the

J. L Guil-Guerrero; El-Hassan Belarbi

2000-01-01

309

Morphology variability of radial pulse wave during exercise.  

PubMed

Pulse wave contains much information on a cardiovascular system. Pulse wave variability during exercise is of great significance as it reflects more information combining with pulse wave under stationary state. This paper studied the morphology variability of radial pulse wave during exercise. Radial pulse waves were collected from 30 subjects with two pressure pulse sensors worn at the wrists of the right and left hands, respectively. Electrocardiography (ECG) was also detected synchronously. After data preprocessing and feature point extraction, the variability of several parameters of pulse wave and ECG were analyzed. It is notable that pulse rate (PR) and heart rate (HR) change synchronously. During the exercise period, both systolic phase and diastolic phase of a radial pulse shorten but the latter is more obvious. The amplitude of the dicrotic notch decreases and even turns negative. Aligning the radial pulse waveforms together, the radial pulse waveforms prior to, during and after exercise coincide with each other except for some details like the tidal wave which fades away during exercise. PMID:25227074

Xu, Lisheng; Yao, Yang; Wang, Hao; He, Dianning; Wang, Lu; Jiang, Yongsheng

2014-01-01

310

Algorithmic Game Theory Column Mario Mavronicolas  

E-print Network

Algorithmic Game Theory Column by Mario Mavronicolas Department of Computer Science, University in Algorithmic Game Theory today. The complexity of this problem has been found to be very sensitive with problems of equilibrium computation. 1 Introduction Noncooperative Game Theory has been providing

Mavronicolas, Marios

311

Intelligent fuzzy supervisory control for distillation columns  

E-print Network

to be controlled. In many difficult process situations such as steelmaking furnaces [7], cement kilns [13], presses in the glass industry [4] and distillation columns [12], such models do not exist. While there are a variety of adaptive techniques which can...

Santhanam, Srinivasan

2012-06-07

312

"Dry-column" chromatography of plant pigments  

NASA Technical Reports Server (NTRS)

Separation of plant pigments which can be accomplished on thin-layer silica plates with mixture of petroleum ether, halocarbon, acetone, and polar solvent can be readily translated into dry-column technique that yields reproducible chromatograms after elution in fashion of liquid chromatography with fluorimeter as detector. Best solvent system was found to be mixture of petroleum ether, dichloromethane, acetone, and ethyl acetate.

Woeller, F. H.; Lehwalt, M. F.; Oyama, V. I.

1973-01-01

313

Thermal Analysis of LANL Ion Exchange Column  

SciTech Connect

This document reports results from an ion exchange column heat transfer analysis requested by Los Alamos National Laboratory (LANL). The object of the analysis is to demonstrate that the decay heat from the Pu-238 will not cause resin bed temperatures to increase to a level where the resin significantly degrades.

Laurinat, J.E.

1999-06-16

314

Column densities of interstellar molecular hydrogen  

NASA Technical Reports Server (NTRS)

Equivalent widths of some 50 lines in the 0-0 to 5-0 Lyman bands of H2 are reported in the spectra of 28 stars. Curves of growth are given and column densities for levels from J = 0 to J = 5 are tabulated, with a few values and upper limits for N(6) and N(7), together with values for b, the velocity spread parameter. In three Orion stars and in rho Leo pairs of components are detected, the difference in radial velocity is determined, and column densities are measured or estimated; tentative identifications are made with the components observed by Hobbs (1969) in the Na D-lines. Column densities for HD are given for 13 stars. Upper limits for column densities in the first and second vibrational levels are listed for several stars; the ratio of N(J = 0) in the v double prime = 1 level to that in the ground vibrational level is less than 2.4 x 10 to the minus 8th power in zeta Oph. Values of a rotational excitation temperature for the higher J levels are given for all the stars. Data are presented which show an apparent increase of velocity dispersion with J for a number of stars, as measured both from the curves of growth and from line widths.

Spitzer, L., Jr.; Cochran, W. D.; Hirshfeld, A.

1974-01-01

315

Density Gradient Columns for Chemical Displays.  

ERIC Educational Resources Information Center

Procedures for preparing density gradient columns for chemical displays are presented. They include displays illustrating acid-base reactions, metal ion equilibria, and liquid density. The lifetime of these metastable displays is surprising, some lasting for months in display cabinets. (JN)

Guenther, William B.

1986-01-01

316

Calibration curves for density-gradient columns  

Microsoft Academic Search

Theoretical calibration curves for density-gradient columns at various stages of their development are derived on the assumption that the behaviour is controlled by a Fick's law diffusion. Curves are given for two sets of initial conditions, corresponding to those most commonly used in practice.

D W Budworth

1962-01-01

317

Vivapure Metal Chelate Mega spin columns  

E-print Network

Chromatography (IMAC) purification devices, which simply can be used in a centrifuge. IMAC is a common columns 2 250 ml centrifuge bottles - standard caps 2 Instruction Manual 1 Specifications Max. volume per centrifuge run 75 ml Recommended centrifugation speed 500 x g - 1000 x g (please refer to protocol) Binding

Lebendiker, Mario

318

Contexts for Column Addition and Subtraction  

ERIC Educational Resources Information Center

In this article, the authors discuss their approach to column addition and subtraction algorithms. Adapting an original idea of Paul Cobb and Erna Yackel's from "A Contextual Investigation of Three-Digit Addition and Subtraction" related to packing and unpacking candy in a candy factory, the authors provided an analogous context by designing…

Lopez Fernandez, Jorge M.; Velazquez Estrella, Aileen

2011-01-01

319

Ionized Columns between Thunderstorms and the Ionosphere  

Microsoft Academic Search

It is shown that, if electrons of relativistic energies are generated within thunder- storms and then 'run away' upward above the thunderclouds, their range is probably only a few kilometers; their ionizing effects are therefore localized. Calculations indicate, however, that the bremsstrahlung produced during the stoppage of the electrons can create ionized columns extending to ionospheric heights (about 100 kin).

R. K. COLE

1966-01-01

320

Inklings: Collected Columns on Leadership and Creativity.  

ERIC Educational Resources Information Center

This book brings together 35 of David P. Campbell's essays originally published as a regular column in a quarterly publication called "Issues and Observations." The articles deal with topics ranging from leadership issues such as risk-taking, executive motivation, decision making, and corporate taboos, to more general concerns such as father-son…

Campbell, David P.

321

WATER COLUMN DATA AND SPECTRAL IRRADIANCE MODEL  

EPA Science Inventory

Water samples collected monthly, for 18 months, from six sites in the Laguna Madre were analyzed to identify and quantify phytopigments using High Performance Liquid Chromatography (HPLC). In addition, water column pigment and nutrient data were acquired at 12 stations in Upper ...

322

Numerical simulation of collapsing volcanic columns  

Microsoft Academic Search

A complex thermofluid dynamic two-phase and two-component flow model is implemented to simulate collapsing volcanic columns. The model involves only one particle size class and accounts for water vapor mixing with air in the atmosphere. The effect of particle collisions in the model is accounted for by a kinetic theory model that solves for the granular temperature and therefore predicts

Flavio Dobran; Augusto Neri; Giovanni Macedonio

1993-01-01

323

Clearance of meprobamate by hemoperfusion over columns of charcoal and Amberlite resin. Studies in a patient.  

PubMed

Perfusion of the blood of a patient with toxic levels of meprobamate through an activated charcoal cartridge resulted in efficient early clearance of the drug, then a decline in extraction. Perfusion through a resin column resulted in total drug extraction without a decline in clearance over four hours. Both procedures were stable with minimal disturbance in hematological values or blood chemistries. This is the first report of in vivo hemoperfusion over resin for meprobamate poisoning. The efficacy and safety of the procedure need emphasis. PMID:743013

Hoy, W; Schwab, G; Freeman, R B

1978-11-01

324

Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns  

NASA Technical Reports Server (NTRS)

This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.

Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro

2001-01-01

325

Analysis of microwave leaky modes propagating through laser plasma filaments column waveguide  

NASA Astrophysics Data System (ADS)

A plasma column waveguide formed by a bundle of closely spaced plasma filaments induced by the propagation of ultrafast laser pulses in air and revived by a longer infrared laser pulse is shown to support microwave radiation. We consider values of both the plasma electron density and microwave frequency for which the refractive index of plasma is lower than the refractive index of air; therefore, a leaky plasma waveguide can be realized in extremely high frequency band. The guiding mechanism does not require high conductance of the plasma and can be easily excited by using commercial femtosecond laser sources. A theoretical study of leaky mode characteristics of isotropic and homogeneous plasma column waveguides is investigated with several values of plasma and waveguide structure parameters. The microwave transmission loss was found to be mainly caused by the microwave leakage through the air-plasma interface and is weakly dependent on the plasma absorption. In spite of losses of microwaves caused by leakage and plasma absorption, it is shown to be much lower than both that accompanying to surface waves attaching to single conducting plasma wire and the free space propagation over distances in the order of the filament length, which opens exciting perspectives for short distance point to point wireless transmission of pulsed-modulated microwaves.

Alshershby, Mostafa; Hao, Zuoqiang; Lin, Jingquan

2012-12-01

326

Analysis of microwave leaky modes propagating through laser plasma filaments column waveguide  

SciTech Connect

A plasma column waveguide formed by a bundle of closely spaced plasma filaments induced by the propagation of ultrafast laser pulses in air and revived by a longer infrared laser pulse is shown to support microwave radiation. We consider values of both the plasma electron density and microwave frequency for which the refractive index of plasma is lower than the refractive index of air; therefore, a leaky plasma waveguide can be realized in extremely high frequency band. The guiding mechanism does not require high conductance of the plasma and can be easily excited by using commercial femtosecond laser sources. A theoretical study of leaky mode characteristics of isotropic and homogeneous plasma column waveguides is investigated with several values of plasma and waveguide structure parameters. The microwave transmission loss was found to be mainly caused by the microwave leakage through the air-plasma interface and is weakly dependent on the plasma absorption. In spite of losses of microwaves caused by leakage and plasma absorption, it is shown to be much lower than both that accompanying to surface waves attaching to single conducting plasma wire and the free space propagation over distances in the order of the filament length, which opens exciting perspectives for short distance point to point wireless transmission of pulsed-modulated microwaves.

Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan [School of Science, Changchun University of Science and Technology, Changchun 130022 (China)

2012-12-15

327

Pulsed IR inductive lasers  

NASA Astrophysics Data System (ADS)

Pulsed inductive discharge is a new alternative method of pumping active gas laser media. The work presents results of experimental investigations of near, mid, and far IR inductive gas lasers (H2, HF, and CO2) operating at different transitions of atoms and molecules with different mechanisms of formation of inversion population. The excitation systems of a pulsed inductive cylindrical discharge (pulsed inductively coupled plasma) and pulsed RF inductive discharge in the gases are developed. Various gas mixtures including H2, N2, He, Ne, F2, NF3, and SF6 are used. Characteristics of near IR H2 laser radiation are investigated. Maximal pulse peak power of 7?kW is achieved. The possibility of using a pulsed inductive discharge as a new method of pumping HF laser active medium is demonstrated. The pulsed RF inductive CO2 laser is created and a total efficiency of 17% is achieved.

Razhev, A. M.; Churkin, D. S.; Kargapol’tsev, E. S.

2014-07-01

328

Effect of application of phosphate and organic manure-based fertilizers on arsenic transformation in soil columns.  

PubMed

The mobility of arsenic in Cambisol under the influence of added barnyard manure and application of a phosphate solution to the soil was described on the basis of column experiments. A soil sample containing 126 mg/kg total As and 3.72 mg/kg specifically-sorbed As was extracted using demineralized water (DIW) or a 28 micromol/l phosphate solution in a column containing untreated soil and in a column with added barnyard fertilizer. The pH, Eh, alkalinity, main components, including DOC, and selected trace elements (Al, Mn, Pb, Cu, Zn, Cd, Cr, Co, Ni, Ba and As) were determined in the extracts. Hydrodynamic tests of the flow and transport of the substances in the columns were carried out. The addition of barnyard manure was manifested in elevated concentrations of the main inorganic components, DOC and Al and a decrease in the Eh value and Mn concentration. Application of a phosphate solution was manifested in a decrease in the NO(3) and SO(4) concentrations, probably as a result of the effect of increased biological fixation. The As concentration in extracts varied from 8.8 to 15.5 microg/l and was not dependent on the composition of the extracting solution or the addition of barnyard fertilizer. PMID:17370134

Sisr, Ludek; Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav; Sebek, Ondrej

2007-12-01

329

Effects of pulse frequency on the microstructure, composition and optical properties of pulsed dc reactively sputtered vanadium oxide thin films  

NASA Astrophysics Data System (ADS)

Vanadium oxide (VOx) thin films were prepared on unheated glass substrate by pulsed dc reactive magnetron sputtering using different pulse frequency. Field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE) measurements were made on the deposited VOx films to characterize the microstructure, composition and optical properties, respectively. It was found that under the same discharge power and argon-oxygen atmosphere, with the increase of pulse frequency, the vertical column-like structure in the films will gradually disappear and the ratio of high-valent VOx to low-valent VOx will obviously elevate. Optical parameters of the VOx films have been obtained by fitting the ellipsometric data (? and?) using the Tauc-Lorentz dispersion relation and a multilayer model (air/roughness layer/VOx/glass). The results demonstrated that pulse frequency plays a critical role in determining the transmittance, refractive index, extinction coefficient and optical band gap etc. The correlations between the microstructure, composition, optical properties and pulse frequency are also given by our experiment results. And the mechanisms for the evolution of the microstructure, composition and optical properties with pulse frequency have been discussed. Overall, due to the pulse frequency had a great effect not only on the growth characteristics but also on the optical properties of the VOx films, thus through variation of the pulse frequency during deposition which provide a convenient and efficient approach to control and optimize the performances of the VOx films.

Dong, Xiang; Wu, Zhiming; Jiang, Yadong; Xu, Xiangdong; Yu, He; Gu, Deen; Wang, Tao

2014-09-01

330

EVALUATION OF SAMPLE EXTRACT CLEANUP USING SOLID-PHASE EXTRACTION CARTRIDGES  

EPA Science Inventory

Fractionation and cleanup of sample extracts prior to instrumental analysis is usually accomplished by column chromatography, gel permeation chromatography, or acid-base partitioning. n this report, the results of a study are described in which we investigated the application of ...

331

Design and Construction of the 3.2 Mev High Voltage Column for Darht II  

E-print Network

A 3.2 MeV injector has been designed and built for the Darht II Project at Los Alamos Lab. The installation of the complete injector system is nearing completion at this time. The requirements for the injector are to produce a 3.2 MeV, 2000 ampere electron pulse with a flattop width of at least 2-microseconds and emittance of less than 0.15 p cm-rad normalized. A large high voltage column has been built and installed. The column is vertically oriented, is 4.4 meters long, 1.2 meters in diameter, and weights 5700 kilograms. A novel method of construction has been employed which utilizes bonded mycalex insulating rings. This paper will describe the design, construction, and testing completed during construction. Mechanical aspects of the design will be emphasized.

Peters, C; Yu, S; Eylon, S; Henestroza, E

2000-01-01

332

Design and Construction of the 3.2 Mev High Voltage Column for Darht II  

E-print Network

A 3.2 MeV injector has been designed and built for the Darht II Project at Los Alamos Lab. The installation of the complete injector system is nearing completion at this time. The requirements for the injector are to produce a 3.2 MeV, 2000 ampere electron pulse with a flattop width of at least 2-microseconds and emittance of less than 0.15 p cm-rad normalized. A large high voltage column has been built and installed. The column is vertically oriented, is 4.4 meters long, 1.2 meters in diameter, and weights 5700 kilograms. A novel method of construction has been employed which utilizes bonded mycalex insulating rings. This paper will describe the design, construction, and testing completed during construction. Mechanical aspects of the design will be emphasized.

C. Peters; B. Elliott; S. Yu; S. Eylon; E. Henestroza

2000-09-28

333

ON THE ORIGIN OF THE HIGH COLUMN DENSITY TURNOVER IN THE H I COLUMN DENSITY DISTRIBUTION  

SciTech Connect

We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N{sub H{sub I}} Almost-Equal-To 10{sup 21} cm{sup -2}, which is present at both z = 0 and z Almost-Equal-To 3, and a lack of systems above N{sub H{sub I}} Almost-Equal-To 10{sup 22} cm{sup -2} at z = 0. Using observations of the column density distribution, we argue that the H I-H{sub 2} transition does not cause the turnover at N{sub H{sub I}} Almost-Equal-To 10{sup 21} cm{sup -2} but can plausibly explain the turnover at N{sub H{sub I}} {approx}> 10{sup 22} cm{sup -2}. We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Ly{alpha} column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over {approx} kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.

Erkal, Denis [Department of Physics, University of Chicago, Chicago, IL 60637 (United States); Gnedin, Nickolay Y. [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kravtsov, Andrey V. [Kavli Institute for Cosmological Physics and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)

2012-12-10

334

Characterization of antioxidant compounds in aqueous coriander extract ( Coriandrum sativum L.)  

Microsoft Academic Search

An aqueous coriander extract obtained through a sequential extraction process, was analysed using chromatography and mass spectrometry in order to identify the phenolic compounds responsible for its antioxidant activity. Four fractions were identified from the crude extract using chromatography in a silica gel column. Their antioxidant activity, according to the ?-carotene\\/linoleic acid model, was similar to one another but inferior

Enayde de Almeida Melo; Jorge Mancini Filho; Nonete Barbosa Guerra

2005-01-01

335

Tooth Extraction  

MedlinePLUS

... loosens the tooth with an instrument called an elevator. Then the dentist uses an instrument called a ... difficult extractions. Smokers and women who take birth control pills are more likely to have a dry ...

336

Column solid phase extraction and flame atomic absorption spectrometric determination of manganese(II) and iron(III) ions in water, food and biological samples using 3-(1-methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid on synthesized graphene oxide.  

PubMed

A modified, selective, highly sensitive and accurate procedure for the determination of trace amounts of manganese and iron ions is established in the presented work. 3-(1-Methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid (MPPC) and graphene oxide (GO) were used in a glass column as chelating reagent and as adsorbent respectively prior to their determination by flame atomic absorption spectrometry. The adsorption mechanism of titled metals complexes on GO was investigated by using computational chemistry approach based on PM6 semi-empirical potential energy surface (PES). The effect of some parameters including pH, flow rate and volume of sample and type, volume and concentration of eluent, as well as the adsorption capacity of matrix ions on the recovery of Mn(II) and Fe(III) was investigated. The limit of detection was 145 and 162 ng L(-1) for Mn(II) and Fe(III), respectively. Calibration was linear over the range of 0.31-355 ?g L(-1) for Mn(II) and 0.34-380 ?g L(-1) for Fe(III) ions. The method was successfully applied for the determination of understudied ions in water, food and biological samples. PMID:24411390

Pourjavid, Mohammad Reza; Sehat, Ali Akbari; Arabieh, Masoud; Yousefi, Seyed Reza; Hosseini, Majid Haji; Rezaee, Mohammad

2014-02-01

337

Countercurrent supercritical fluid extraction and fractionation of alcoholic beverages.  

PubMed

A procedure for the recovery of aromatic extracts from distilled alcoholic beverages by means of a countercurrent supercritical fluid extraction (CC-SFE) on a pilot plant scale is studied. The beverage is directly in contact with the carbon dioxide current in a packed column, and the extracts are recovered in two different fractionation cells, where the depressurization occurs. The proposed method allows the selective extraction of aromatic components of the brandy flavor, rendering a high-value concentrated extract and a colored residue without brandy aroma. The content in ethanol of the aromatic extract can be modified by tuning the extraction/fractionation conditions, rendering from 15 to 95% recovery. The effect of the main variables, including extraction pressure and quality of extracting CO(2), has been tested. PMID:11308342

Seńoráns, F J; Ruiz-Rodríguez, A; Ibańez, E; Tabera, J; Reglero, G

2001-04-01

338

DNA Extraction  

NSDL National Science Digital Library

In this activity related to plant biotechnology, learners extract DNA from fruit to investigate how it looks and feels. The procedure is similar to what scientists have to do before they can use information contained in this DNA. This lesson guide includes procedure and discussion questions to help learners reflect on the process and purpose of DNA extraction. Modifications for younger learners are included in a related PDF (see related resources).

2012-06-26

339

Schematic Diagram of Physical and Chemical Steps to extract Al and Be from Quartz-bearing rocks Quartz separation and pre-  

E-print Network

Aliquot (TSA) C.4 Fe column C.5 Be column C.6 Purifying Be fraction C.7 Al column C.8 Purifying Al Isotopes Lab The following guidelines describe how to extract 26Al and 10Be from quartz-bearing rocks

Bookhagen, Bodo

340

Bevalac extraction  

SciTech Connect

This report will describe some of the general features of the Bevatron extraction system, primarily the dependence of the beam parameters and extraction magnet currents on the Bevalac field. The extraction magnets considered are: PFW, XPl, XP2, XS1, XS2, XM1, XM2, XM3, XQ3A and X03B. This study is based on 84 past tunes (from 1987 to the present) of various ions (p,He,O,Ne,Si,S,Ar,Ca,Ti,Fe,Nb,La,Au and U), for Bevalac fields from 1.749 to 12.575 kG, where all tunes included a complete set of beam line wire chamber pictures. The circulating beam intensity inside the Bevalac is measured with Beam Induction Electrodes (BIE) in the South Tangent Tank. The extracted beam intensity is usually measured with the Secondary Emission Monitor (SEM) in the F1-Box. For most of the tunes the extraction efficiency, as given by the SEM/BIE ratio, was not recorded in the MCR Log Book, but plotting the available Log Book data as a function of the Bevalac field, see Fig.9, we find that the extraction efficiency is typically between 30->60% with feedback spill.

Kalnins, J.G.; Krebs, G.; Tekawa, M.; Cowles, D.; Byrne, T.

1992-02-01

341

Developing the Pulsed Fission-Fusion (PuFF) Engine  

NASA Technical Reports Server (NTRS)

In September 2013 the NASA Innovative Advanced Concept (NIAC) organization awarded a phase I contract to the PuFF team. Our phase 1 proposal researched a pulsed fission-fusion propulsion system that compressed a target of deuterium (D) and tritium (T) as a mixture in a column, surrounded concentrically by Uranium. The target is surrounded by liquid lithium. A high power current would flow down the liquid lithium and the resulting Lorentz force would compress the column by roughly a factor of 10. The compressed column would reach criticality and a combination of fission and fusion reactions would occur. Our Phase I results, summarized herein, review our estimates of engine and vehicle performance, our work to date to model the fission-fusion reaction, and our initial efforts in experimental analysis.

Adams, Robert B.; Cassibry, Jason; Bradley, David; Fabisinski, Leo; Statham, Geoffrey

2014-01-01

342

W.P. Davies Newspaper Columns  

NSDL National Science Digital Library

Born on a farm in Ontario, William Preston Davies came to the plains of North Dakota at the age of 20. In his early 30s, he began a long career as a journalist, and worked as an editor and writer at the Northwest News, the Grand Forks Plaindealer, and the Grand Forks Herald. In 1930, Davies began writing a daily column called "That Reminds Me". This digital collection from the University of North Dakota's Chester Fritz Library gives users access to his daily insights and observations on North Dakota life. The first column available here dates from April 1930 and the last one is from September 1943. There is nary a subject that Davies doesn't cover, as he winds his way through topics like farm policy, local wit and lore, and Charlie Chaplin.

343

Modeling of Crystalline Silicotitanate Ion Exchange Columns  

SciTech Connect

Non-elutable ion exchange is being considered as a potential replacement for the In-Tank Precipitation process for removing cesium from Savannah River Site (SRS) radioactive waste. Crystalline silicotitanate (CST) particles are the reference ion exchange medium for the process. A major factor in the construction cost of this process is the size of the ion exchange column required to meet product specifications for decontaminated waste. To validate SRS column sizing calculations, SRS subcontracted two reknowned experts in this field to perform similar calculations: Professor R. G. Anthony, Department of Chemical Engineering, Texas A&038;M University, and Professor S. W. Wang, Department of Chemical Engineering, Purdue University. The appendices of this document contain reports from the two subcontractors. Definition of the design problem came through several meetings and conference calls between the participants and SRS personnel over the past few months. This document summarizes the problem definition and results from the two reports.

Walker, D.D.

1999-03-09

344

Fast Pulsing Neutron Generators for Security Application  

SciTech Connect

Active neutron interrogation has been demonstrated to be an effective method of detecting shielded fissile material. A fast fall-time/fast pulsing neutron generator is needed primarily for differential die-away technique (DDA) interrogation systems. A compact neutron generator, currently being developed in Lawrence Berkeley National Laboratory, employs an array of 0.6-mm-dia apertures (instead of one 6-mm-dia aperture) such that gating the beamlets can be done with low voltage and a small gap to achieve sub-microsecond ion beam fall time and low background neutrons. Arrays of 16 apertures (4x4) and 100 apertures (10x10) have been designed and fabricated for a beam extraction experiment. The preliminary results showed that, using a gating voltage of 1200 V and a gap distance of 1 mm, the fall time of extracted ion beam pulses is approximately 0.15 mu s at beam energies of 1000 eV.

Ji, Q.; Regis, M.; Kwan, J. W.

2009-04-24

345

Isolated Attosecond Pulse Generation without the Need to Stabilize the Carrier-Envelope Phase of Driving Lasers  

SciTech Connect

Single isolated attosecond pulses can be extracted from a pulse train with an ultrafast gate in the generation target. By setting the gate width sufficiently narrow with the generalized double optical gating, we demonstrate that single isolated attosecond pulses can be generated with any arbitrary carrier-envelope phase value of the driving laser. The carrier-envelope phase only affects the photon flux, not the pulse duration or contrast. Our results show that isolated attosecond pulses can be generated using carrier-envelope phase unstabilized 23 fs pulses directly from chirped pulse amplifiers.

Gilbertson, Steve; Khan, Sabih D.; Wu Yi; Chini, Michael [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Chang Zenghu [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); CREOL and Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States)

2010-08-27

346

Cadmium removal in a biosorption column  

Microsoft Academic Search

New biosorbent material derived from a ubiquitous brown marine alga Ascophyllum nodosum has been examined in packed-bed flow-through sorption columns. It effectively removed 10 mg\\/L of cadmium down to 1.5 ppb levels in the effluent, representing 99.985% removal. The experimental methodology used was based on the early Bohart and Adams sorption model, resulting in quantitative determination of the characteristic process

B. Volesky; I. Prasetyo

1994-01-01

347

Performance of Reinforced Concrete Column Lap Splices  

E-print Network

OF SCIENCE August 2009 Major Subject: Civil Engineering PERFORMANCE OF REINFORCED CONCRETE COLUMN LAP SPLICES A Thesis by RYAN ALBERSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE Approved by: Committee Co-Chairs, Joseph Bracci David Trejo Committee Member Mohammed Haque Head of Department, David Rosowsky August 2009 Major Subject: Civil Engineering iii ABSTRACT...

Alberson, Ryan M.

2010-01-14

348

Random pulse generator  

NASA Technical Reports Server (NTRS)

An exemplary embodiment of the present invention provides a source of random width and random spaced rectangular voltage pulses whose mean or average frequency of operation is controllable within prescribed limits of about 10 hertz to 1 megahertz. A pair of thin-film metal resistors are used to provide a differential white noise voltage pulse source. Pulse shaping and amplification circuitry provide relatively short duration pulses of constant amplitude which are applied to anti-bounce logic circuitry to prevent ringing effects. The pulse outputs from the anti-bounce circuits are then used to control two one-shot multivibrators whose output comprises the random length and random spaced rectangular pulses. Means are provided for monitoring, calibrating and evaluating the relative randomness of the generator.

Lindsey, R. S., Jr. (inventor)

1975-01-01

349

SNS EXTRACTION KICKER POWER SUPPLY PROTOTYPE TEST  

SciTech Connect

The SNS (Spallation Neutron Source) accumulator ring Extraction System consists of a Fast kicker and a Lambertson Septum magnet. The proposed design will use 14 kicker magnets powered by an Extraction Kicker Power Supply System. They will eject the high power beam from the SNS accumulator ring into RTBT (Ring to Target Beam Tunnel) through a Lambertson Septum magnet. This paper describes some test results of the SNS Extraction Kicker power supply prototype. The high repetition rate of 60 pulse per second operation is the challenging part of the design. In the prototype testing, a 3 kA damp current of 700ns pulse-width, 200 nS rise time and 60 Hz repetition rate at 32 kV PFN operation voltage has been demonstrated. An Extraction kicker power supply system design diagram is depicted.

MI,J.L.; SANDBERG,J.; SANDERS,R.; SOUKAS,A.; ZHANG,W.

2000-06-27

350

[Spectral investigation of atmospheric pressure plasma column].  

PubMed

Atmospheric pressure plasma column has many important applications in plasma stealth for aircraft. In the present paper, a plasma column with a length of 65 cm was generated in argon at atmospheric pressure by using dielectric barrier discharge device with water electrodes in coaxial configurations. The discharge mechanism of the plasma column was studied by optical method and the result indicates that a moving layer of light emission propagates in the upstream region. The propagation velocity of the plasma bullet is about 0.6 x 10(5) m x s(-1) through optical measurement. Spectral intensity ratios as functions of the applied voltage and driving frequency were also investigated by spectroscopic method. The variation in spectral intensity ratio implies a change in the averaged electron energy. Results show that the averaged electron energy increases with the increase in the applied voltage and the driving frequency. These results have significant values for industrial applications of the atmospheric pressure discharge and have extensive application potentials in stealth for military aircraft. PMID:23016319

Li, Xue-Chen; Chang, Yuan-Yuan; Xu, Long-Fei

2012-07-01

351

Physical extraction of microorganisms from water-saturated, packed sediment.  

PubMed

Microbial characterization of aquifers should include samples of both suspended and attached microorganisms (biofilms). We investigated the effect of shear, sonication, and heat on the extraction of microorganisms from water-saturated, packed sediment columns containing established biofilms. Shear was studied by increasing flow velocity of the column eluent, sonication by treating the columns with ultrasound at different power levels, and heat by warming up the column eluent to different temperatures. Effluent cell concentrations were used as a measure of extraction efficiency. Dissolved organic carbon and adenosine tri-phosphate (ATP) concentrations were used to corroborate cell-extraction results. Additionally, ATP was used as an indicator of cell-membrane integrity. Extraction quality was determined by comparing terminal-restriction fragment length polymorphism (T-RFLP) profiles of extracted bacterial communities with destructively sampled sediment-community profiles. Sonication and heat increased the extraction efficiency up to 200-fold and yielded communities comparable to the sediment community. These treatments showed high potential for in-situ application in aquifers. PMID:24961067

Ugolini, Fabio; Schroth, Martin H; Bürgmann, Helmut; Zeyer, Josef

2014-05-01

352

CAR MACHINE SHOP, FIRST FLOOR, DETAIL OF WOOD COLUMN AND ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

CAR MACHINE SHOP, FIRST FLOOR, DETAIL OF WOOD COLUMN AND INVERTED KING-POST TRUSS TO PROVIDE INCREASED SPAN BETWEEN COLUMNS, LOOKING SOUTH. - Southern Pacific, Sacramento Shops, Car Machine Shop, 111 I Street, Sacramento, Sacramento County, CA

353

46 CFR 174.085 - Flooding on column stabilized units.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special...watertight bulkheads, measured at the column periphery, is equal to or less than one-eighth of the column perimeter at...

2010-10-01

354

6. HISTORIC AMERICAN BUILDINGS SURVEY, INTERIOR SHOWING ORIGINAL GRANITE COLUMNS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. HISTORIC AMERICAN BUILDINGS SURVEY, INTERIOR SHOWING ORIGINAL GRANITE COLUMNS AND COLUMN BRICKFACED AFTER THE GREAT FIRE 1904 - Old U.S. Appraisers Stores, Gay & Lombard Streets, Baltimore, Independent City, MD

355

Query execution in column-oriented database systems  

E-print Network

There are two obvious ways to map a two-dimension relational database table onto a one-dimensional storage interface: store the table row-by-row, or store the table column-by-column. Historically, database system implementations ...

Abadi, Daniel J

2008-01-01

356

20. Detail of 8" square solid wood column at fruit ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. Detail of 8" square solid wood column at fruit and vegetable storage room; note ledger plates bolted to top of column - Fort Hood, World War II Temporary Buildings, Cold Storage Building, Seventeenth Street, Killeen, Bell County, TX

357

19. Detail of builtup 5" x 13" column at fruit ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. Detail of built-up 5" x 13" column at fruit and vegetable storage room; note ledger plates bolted to top of column - Fort Hood, World War II Temporary Buildings, Cold Storage Building, Seventeenth Street, Killeen, Bell County, TX

358

ANALYSIS OF FERRIC AND FERROUS IONS IN SOIL EXTRACTS BY ION CHROMATOGRAPHY  

EPA Science Inventory

A method using ion chromatography (IC) for the analysis of ferrous (Fe 2+) and ferric (Fe 3+) ions in soil extracts has been developed. This method uses an ion exchange column with detection at 520 nm after post-column derivatization. Selectivity is achieved by using an anionic...

359

Cross flow cyclonic flotation column for coal and minerals beneficiation  

DOEpatents

An apparatus and process for the separation of coal from pyritic impurities using a modified froth flotation system. The froth flotation column incorporates a helical track about the inner wall of the column in a region intermediate between the top and base of the column. A standard impeller located about the central axis of the column is used to generate a centrifugal force thereby increasing the separation efficiency of coal from the pyritic particles and hydrophillic tailings.

Lai, Ralph W. (Upper St. Clair, PA); Patton, Robert A. (Pittsburgh, PA)

2000-01-01

360

Cross flow flotation column for coal and minerals beneficiation  

SciTech Connect

An apparatus and process are disclosed for the separation of coal from pyritic impurities using a modified froth flotation system. The froth flotation column incorporates a helical track about the inner wall of the column in a region intermediate between the top and base of the column. A standard impeller located about the central axis of the column is used to generate a centrifugal force thereby increasing the separation efficiency of coal from the pyritic particles and hydrophilic tailings.

Lai, Ralph W.; Patton, Robert A.

1997-12-01

361

Surface-initiated molecularly imprinted polymeric column: In situ synthesis and application for semi-preparative separation by high performance liquid chromatography  

Microsoft Academic Search

In this work, we prepared a monolithic and surface initiated molecularly imprinted polymeric (MIP) column for HPLC and explored its application for template separation from plant extract. The silica beads (40–60?m) were coupled with initiator on the surface and then packed in to a stainless steel HPLC column. The pre-polymerization mixture (the template, functional monomer and crosslinker were emodin, acrylamide

Jiangyong Gu; Hu Zhang; Gu Yuan; Lirong Chen; Xiaojie Xu

2011-01-01

362

Water hammer with column separation: A historical review  

Microsoft Academic Search

Column separation refers to the breaking of liquid columns in fully filled pipelines. This may occur in a water-hammer event when the pressure in a pipeline drops to the vapor pressure at specific locations such as closed ends, high points or knees (changes in pipe slope). The liquid columns are separated by a vapor cavity that grows and diminishes according

A. Bergant; A. R. Simpson; A. S. Tijsseling

2006-01-01

363

Optimum Absorber Parameters for Tuned Liquid Column Dampers  

Microsoft Academic Search

Tuned liquid column dampers (TLCDs) are a class of tuned liquid dampers that impart indirect damping to the primary structure through oscillations of the liquid column in a U-shaped container. The energy dissipation in the water column results from the passage of the liquid through an orifice with inherent head-loss characteristics. The overall damping in a TLCD depends on the

Swaroop K. Yalla; Ahsan Kareem

2000-01-01

364

Optimal Extraction of Echelle Spectra  

NASA Astrophysics Data System (ADS)

The extraction of the echelle spectra registered with a CCD detector represents a big challenge because of three reasons: (1) the pixel sampling is often close or worse then optimal, (2) spectral orders are curved and tilted with respect to the CCD rows (or columns) and (3) every pixel contains additional noise coming from various sources as illustrated in Figure 1. The main goal of an optimal extraction is to recover as much of the science signal while minimizing the contribution of the noise. Here we present the Slit Function Decomposition algorithm which replaces the summation in a sliding window with a reconstruction of the slit illumination profile. The reconstruction is formulated as an inverse problem solved by iterations and it is robust against most of the systematic problems including cosmic rays and cosmetic defects.

Piskunov, Nikolai

365

Opportunities in pulse combustion  

SciTech Connect

In most pulse combustors, the combustion occurs near the closed end of a tube where inlet valves operate in phase with the pressure amplitude variations. Thus, within the combustion zone, both the temperature and the pressure oscillate around a mean value. However, the development of practical applications of pulse combustion has been hampered because effective design requires the right combination of the combustor's dimensions, valve characteristics, fuel/oxidizer combination, and flow pattern. Pulse combustion has several additional advantages for energy conversion efficiency, including high combustion and thermal efficiency, high combustion intensity, and high convective heat transfer rates. Also, pulse combustion can be self-aspirating, generating a pressure boost without using a blower. This allows the use of a compact heat exchanger that may include a condensing section and may obviate the need for a chimney. In the last decade, these features have revived interest in pulse combustion research and development, which has resulted in the development of a pulse combustion air heater by Lennox, and a pulse combustion hydronic unit by Hydrotherm, Inc. To appraise this potential for energy savings, a systematic study was conducted of the many past and present attempts to use pulse combustion for practical purposes. The authors recommended areas where pulse combustion technology could possibly be applied in the future and identified areas in which additional R and D would be necessary. Many of the results of the study project derived from a special workshop on pulse combustion. This document highlights the main points of the study report, with particular emphasis on pulse combustion application in chemical engineering.

Brenchley, D.L.; Bomelburg, H.J.

1985-10-01

366

Extractant composition  

DOEpatents

An organic extracting solution useful for separating elements of the actinide series of the periodic table from elements of the lanthanide series, where both are in trivalent form. The extracting solution consists of a primary ligand and a secondary ligand, preferably in an organic solvent. The primary ligand is a substituted monothio-1,3-dicarbonyl, which includes a substituted 4-acyl-2-pyrazolin-5-thione, such as 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT). The secondary ligand is a substituted phosphine oxide, such as trioctylphosphine oxide (TOPO).

Smith, Barbara F. (Los Alamos, NM); Jarvinen, Gordon D. (Los Alamos, NM); Ryan, Robert R. (Los Alamos, NM)

1990-01-01

367

Comparison between a spray column and a sieve tray column operating as liquid-liquid heat exchangers  

NASA Astrophysics Data System (ADS)

The performance of the spray column as a heat exchanger was shown to correlate with the model of Letan-Kehat which has as a basis that the heat transfer is dominated by the wakeshedding characteristics of the drops over much of the column length. This model defines several hydrodynamic zones along the column of which the wake formation zone at the bottom appears to have the most efficient heat transfer. The column was also operated with four perforated plates spaced two column diameters apart in order to take advantage of the wake formation zone heat transfer. It is shown that the overall volumetric heat transfer coefficient in a perforated plate column is increased by a minimum of eleven percent over that in a spray column. A hydrodynamic model that predicts the performance of a perforated plate column is suggested.

Keller, A.; Jacobs, H. R.; Boehm, R. F.

1980-12-01

368

Comparison between a spray column and a sieve tray column operating as liquid-liquid heat exchangers  

NASA Astrophysics Data System (ADS)

The reported investigation was conducted in connection with research intended to improve the efficiency of direct contact devices for geothermal and solar applications. The investigation had the objective to evaluate the effect of adding sieve trays to the laboratory column used in studies concerned with the development of models for spray column heat transfer. Hot water is pumped from a supply vessel into the top of the heat exchanger column where, as the continuous phase, it flows down through the column. The dispersed phase is kerosene. Using an identical pump to that used for the water, the kerosene flows into a dispersion plate in the bottom of the column. The droplets rise through the column and coalesce at the top. It was found that the heat transfer performance of the perforated plate column was significantly improved over that in a spray column for similar operating conditions.

Keller, A. S.; Jacobs, H. R.; Boehm, R. F.

369

Residual diesel measurement in sand columns after surfactant/alcohol washing  

SciTech Connect

A new simple gravimetric technique has been designed to determine residual oil saturation of complex hydrocarbon mixtures (e.g., diesel) in sand column experiments because reliable methods are lacking. The He/N{sub 2} technique is based on drying of sand columns by circulating helium gas to drag oil droplets in a cold trap (liquid nitrogen). With this technique, residual diesel measurement can be performed easily immediately after alcohol/surfactant washing and in the same lab. For high residual diesel content in Ottawa sand (25 to 30 g/kg), the technique is much more accurate ({+-} 2% or 600 mg/kg) than the standard analytical methods for the determination of mineral oil and grease. The average relative error on partial diesel dissolution in sand column estimated after alcohol/surfactant flooding (residual saturation of 10 to 15 g/kg) is as low as 5%. The precision of the He/N{sub 2} technique is adequate to compare relative efficiency of washing solutions when partial extraction of residual oil in Ottawa sand columns is performed. However, this technique is not adapted for determination of traces of oil in sediment or for environmental control of contaminated soils. Each diesel determination by the He/N{sub 2} technique costs less than $8 in chemical products (helium and liquid nitrogen). A simple laboratory drying setup can be built for less than $400 which makes this technique valuable for diesel analyses when a large number of tests are required.

Martel, R.; Gelinas, P.J. [Laval Univ., Quebec City, Quebec (Canada)

1996-01-01

370

Bioretention column study of bacteria community response to salt-enriched artificial stormwater.  

PubMed

Cold climate cities with green infrastructure depend on soil bacteria to remove nutrients from road salt-enriched stormwater. Our research examined how bacterial communities in laboratory columns containing bioretention media responded to varying concentrations of salt exposure from artificial stormwater and the effect of bacteria and salt on column effluent concentrations. We used a factorial design with two bacteria treatments (sterile, nonsterile) and three salt concentrations (935, 315, and 80 ppm), including a deionized water control. Columns were repeatedly saturated with stormwater or deionized and then drained throughout 5 wk, with the last week of effluent analyzed for water chemistry. To examine bacterial communities, we extracted DNA from column bioretention media at time 0 and at week 5 and used molecular profiling techniques to examine bacterial community changes. We found that bacterial community taxa changed between time 0 and week 5 and that there was significant separation between taxa among salt treatments. Bacteria evenness was significantly affected by stormwater treatment, but there were no differences in bacterial richness or diversity. Soil bacteria and salt treatments had a significant effect on the effluent concentration of NO, PO, Cu, Pb, and Zn based on ANOVA tests. The presence of bacteria reduced effluent NO and Zn concentrations by as much as 150 and 25%, respectively, while having a mixed effect on effluent PO concentrations. Our results demonstrate how stormwater can affect bacterial communities and how the presence of soil bacteria improves pollutant removal by green infrastructure. PMID:23128752

Endreny, Theodore; Burke, David J; Burchhardt, Kathleen M; Fabian, Mark W; Kretzer, Annette M

2012-01-01

371

Identification of flow regime in a slurry bubble column by Hilbert-Huang transform analysis  

NASA Astrophysics Data System (ADS)

Experiments were conducted in a two-dimensional (2-D) slurry bubble column, which had a length of 0.1m, a width of 0.01m and a total height of 0.8m. The gas phase was oil-free air, tap water was used as the liquid phase, glass powders with particle diameter of 58?m-75?m constituted the solid phase, which belonged to the Geldart A particles. Time-domain analysis and the Hilbert-Huang transform methods were employed to analyze the differential pressure signals obtained and to identify the transition points of the flow regimes in the slurry bubble column. Useful qualitative and quantitative information about the changes in flow structure and particle distributions were extracted. Changes in the standard deviation, skewness and flatness of measured pressure time series with superficial gas velocity are proposed. Hilbert-Huang transform was applied to extract information from signals, and flow structures of the slurry bubble column were characterized by the energy distribution of the multi-resolution signals and the EMD energy entropy. Particle distributions were obtained and analyzed from flow pattern images.

Li, Weiling; Zhong, Wenqi; Jin, Baosheng; Xiao, Rui

2013-06-01

372

Pulse magnetic welder  

Microsoft Academic Search

A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the

D. W. Christiansen; W. F. Brown

1984-01-01

373

Magnetic pulse welding technology  

Microsoft Academic Search

In this paper, the benefits of using Magnetic Pulse machine which is belong to Non-conventional machine instead of conventional machine. Magnetic Pulse Technology is used for joining dissimilar metals, and for forming and cutting metals. It is a non contact technique. Magnetic field is used to generate impact magnetic pressure for welding and forming the work piece by converted the

Ahmad K. Jassim

2010-01-01

374

Pulsed magnetic welding  

Microsoft Academic Search

Solid state welding techniques are an alternative to fusion welding. Two solid state welding techniques are pulsed magnetic welding and explosive bonding. Both achieve bonds by impacting the metals to be joined at high velocity. Development of the pulsed magnetic welding process by Hanford Engineers for fuel fabrication may make this process useful for a variety of other applications. Hanford

Sheely

1986-01-01

375

Rapid pulsed microwave propagation  

Microsoft Academic Search

Transit time measurements of the leading edge of pulse modulated microwaves in open space and inside a rectangular waveguide have been performed. The experimental setup used is described. Both measurements show that a part of the energy associated with the leading edge of the pulse propagates with the phase velocity. Calibration techniques and repeated measurements confirm this phenomenon

George C. Giakos; T. Koryu Ishii

1991-01-01

376

Extraction by lithium chloride of hydroxyproline-rich glycoproteins from intact cells of Chlamydomonas reinhardii.  

PubMed

A procedure has been developed to isolate and analyse the cell-wall glycoproteins of Chlamydomonas reinhardii. Under appropriate conditions, cell-wall glycoproteins can be quantitatively extracted from intact cells by aqueous LiCl. Although proteins and glycoproteins, which are presumably not related to the cell wall, are coextracted with the cell-wall subunits, these components can be readily identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis as demonstrated by comparative analysis of LiCl-extracts from wild-type cells and the cell-wall-deficient mutant CW-15. Apart from the high-molecular-weight cell-wall components, two glycoproteins with apparent molecular weights (Mrs) of 36000 and 66000 were found to be present in LiCl-extracts of wild-type cells but absent in LiCl-extracts from the cell-wall-less mutant. Pulse-labeling experiments with [(3)H]proline and [(35)S]methionine revealed that the LiCl-extracts contained - in addition to the well-known cell-wall subunits - proteins of lower molecular weight, which are also preferentially labeled with [(3)H]proline. Protein components with Mrs of 68000, 44000, 36000, 26000 and 22000 were found to be more strongly labeled with [(3)H]proline than with [(35)S]methionine, whereas protein components with Mrs of 57000 and 52000 were more prominent after labeling with [(35)S]methionine. The portion of cell-wall subunits within the total amount of proteins extracted by LiCl was calculated to be at least 10% on the basis of the amount of hydroxyproline. Self-assembly of cell walls could be demonstrated after dialysis against water of a mixture of crude LiCl-extract and purified, insoluble, inner wall layers. Cell-wall glycoproteins could be enriched by gel exclusion chromatography of crude LiCl-extracts on Sepharose CL-4B columns equilibrated with 1 mol l(-1) LiCl. PMID:24249608

Voigt, J

1985-06-01

377

[Extraction and HPLC analysis of alkaloids in goldenseal].  

PubMed

An ambient extraction of goldenseal root powder followed by HPLC analysis of the alkaloids on a Zorbax Rapid Resolution Eclipse XDB-C18 column provides an accurate method for the determination of key alkaloids in goldenseal, including berberine and hydrastine. The extraction and HPLC analysis can be applied to several other alkaloids, including canadine, hydrastinine, and palmatine, and may be applicable to other berberine-containing plant roots. The Rapid Resolution Eclipse XDB-C18 column is used for an isocratic separation with high resolution of all componentsin under 15 minutes. PMID:15969129

Weber, Holly A; Joseph, Maureen

2004-03-01

378

Composite Pulse Tube  

NASA Technical Reports Server (NTRS)

A modification of the design of the pulse tube in a pulse-tube cryocooler reduces axial thermal conductance while preserving radial thermal conductance. It is desirable to minimize axial thermal conductance in the pulse-tube wall to minimize leakage of heat between the warm and cold ends of the pulse tube. At the same time, it is desirable to maximize radial thermal conductance at the cold end of the pulse tube to ensure adequate thermal contact between (1) a heat exchanger in the form of a stack of copper screens inside the pulse tube at the cold end and (2) the remainder of the cold tip, which is the object to which the heat load is applied and from which heat must be removed. The modified design yields a low-heat-leak pulse tube that can be easily integrated with a cold tip. A typical pulse tube of prior design is either a thin-walled metal tube or a metal tube with a nonmetallic lining. It is desirable that the outer surface of a pulse tube be cylindrical (in contradistinction to tapered) to simplify the design of a regenerator that is also part of the cryocooler. Under some conditions, it is desirable to taper the inner surface of the pulse tube to reduce acoustic streaming. The combination of a cylindrical outer surface and a tapered inner surface can lead to unacceptably large axial conduction if the pulse tube is made entirely of metal. Making the pulse-tube wall of a nonmetallic, lowthermal- conductivity material would not solve the problem because the wall would not afford the needed thermal contact for the stack of screens in the cold end. The modified design calls for fabricating the pulse tube in two parts: a longer, nonmetallic part that is tapered on the inside and cylindrical on the outside and a shorter, metallic part that is cylindrical on both the inside and the outside. The nonmetallic part can be made from G-10 fiberglass-reinforced epoxy or other low-thermal-conductivity, cryogenically compatible material. The metallic part must have high thermal conductivity in the cryogenic temperature range and would typically be made of pure copper to satisfy this requirement. The metallic part is bonded to the nonmetallic part with epoxy. Copper screens are inserted in the metallic part to form the cold-end heat exchanger, then the assembled pulse tube is inserted in the cold tip.

Martin, Jerry L.; Cloyd, Jason H.

2007-01-01

379

Short pulse test set  

NASA Astrophysics Data System (ADS)

This report discusses the construction and operation of the Short Pulse Test Set that has been built for the U.S. Army Missile Command for the purpose of applying short (25 to 100 nanosecond), high voltage pulses to electronic explosive devices (EEDs) in both the pin-to-pin and pins-to-case mode. The test set employs the short pulse generating techniques first described in the Franklin Institute Research Laboratories (now Franklin Research Center) Report I-C3410, 'Pins-to-Case Short Pulse Sensitivity Studies for the Atlas DC Switch', December 1974. This report, authored by Ramie H. Thompson, was prepared for Picatinny Arsenal under contract DAAA21-72C-0766. The test set described herein utilizes a computer controlled high speed digitizer to monitor the pulse voltage and current and provides software to process and display these data.

1990-11-01

380

Chaotic Pulse Trains  

E-print Network

We study a third-order nonlinear ordinary differential equation whose solutions, under certain specific conditions, are individual pulses. These correspond to homoclinic orbits in the phase space of the equation and we study the possible pulse types in some detail. Sufficiently close to the conditions under which a homoclinic orbit exists, the solutions take the form of trains of well-separated pulses. A measure of closeness to homoclinic conditions provides a small parameter for the development of an asymptotic solution consisting of superposed, isolated pulses. The solvability condition in the resulting singular perturbation theory is a {\\its timing map} relating successive pulse spacings. This map of the real line onto itself, together with the known form of the homoclinic orbit, provides a concise and accurate solution of the equation.

N. J. Balmforth; G. R. Ierley; E. A. Spiegel

1993-09-08

381

Pulsed hall thruster system  

NASA Technical Reports Server (NTRS)

A pulsed Hall thruster system includes a Hall thruster having an electron source, a magnetic circuit, and a discharge chamber; a power processing unit for firing the Hall thruster to generate a discharge; a propellant storage and delivery system for providing propellant to the discharge chamber and a control unit for defining a pulse duration .tau.<0.1d.sup.3.rho./m, where d is the characteristic size of the thruster, .rho. is the propellant density at standard conditions, and m is the propellant mass flow rate for operating either the power processing unit to provide to the Hall thruster a power pulse of a pre-selected duration, .tau., or operating the propellant storage and delivery system to provide a propellant flow pulse of duration, .tau., or providing both as pulses, synchronized to arrive coincidentally at the discharge chamber to enable the Hall thruster to produce a discreet output impulse.

Hruby, Vladimir J. (Inventor); Pote, Bruce M. (Inventor); Gamero-Castano, Manuel (Inventor)

2004-01-01

382

Nanosecond Pulse Generator with Variable Pulse Duration for the Study of Pulse Induced Biological Effects  

Microsoft Academic Search

We have developed a Blumlein line pulse generator which utilizes the superposition of electrical pulses launched from two individually switched pulse forming lines. By using a fast power MOSFET as a switch on each end of the Blumlein line, we were able to generate pulses with amplitudes of 1 kV across a 100-Omega load. Pulse duration and polarity can be

J. F. Kolb; S. Scarlett; J. Cannone; J. Zhuang; C. Osgood; K. H. Schoenbach; A. de Angelis; L. Zeni

2008-01-01

383

Mass transfer in a wetted wall column  

E-print Network

internal diameter were employed. The equipment was operated so that an annular film of liquid flowed dove the column countercurrent to a stream of gas, The amount of liquid that evaporated into the gas was reassured and then used to calculate a mass... transfer coefficient. The gas-liquid systems used in the final correlation are air water, isobutane-isopropyl alcohol, air-isopro~ ~1 alcohol~ air normal bu. yl alcohol, and air toluene. It has been noted that the flow conditions of the annular liquid...

Platt, Allison M

1950-01-01

384

A review of oscillating water columns.  

PubMed

This paper considers the history of oscillating water column (OWC) systems from whistling buoys to grid-connected power generation systems. The power conversion from the wave resource through to electricity via pneumatic and shaft power is discussed in general terms and with specific reference to Voith Hydro Wavegen's land installed marine energy transformer (LIMPET) plant on the Scottish island of Islay and OWC breakwater systems. A report on the progress of other OWC systems and power take-off units under commercial development is given, and the particular challenges faced by OWC developers reviewed. PMID:22184660

Heath, T V

2012-01-28

385

Characterization of some extracts for therapeutic use by GC/MS  

NASA Astrophysics Data System (ADS)

A liquid-liquid extraction method (LLE), compared with a solid-phase extraction method (SPE), was used for characterizing some plant extracts for therapeutic use. Precision of the extraction methods gave relative standard deviation lower than 3%. The extracts were analyzed by GC-FID and GC-MS. A HP-5 capillary column, 30 m × 0.32 mm, 0.25 ?m film thickness was used. By using an appropriate mixture of solvents, good recovery mean values were obtained by LLE (81%) comparable with the recoveries of other extraction methods as SPE (92%). The study was applied to characterize the compounds of therapeutic value extracted from herb plants.

Iordache, Andreea Maria; Culea, Monica; Cozar, Onuc

2009-08-01

386

[Determination of amino acids in Galli Gigerii endothelium corneum by HPLC with pre-column derivatization].  

PubMed

Hydrolytic amino acids were extracted by acid hydrolysis method, then derivatized with phenyl isothiocyanate (PITC). And the samples were analysed by HPLC on an Ultimate Prime C18 (4.6 mm x 250 mm, 5 microm) column with gradient elution of 0.1 mol x L(-1) sodium acetate buffer solution (adjusted to pH 6. 5)-acetonitrile (93:7) (A) and acetonitrile-water (8:2) (B) at a flow rate of 1.0 mL x min(-1). Column temperature was 40 degrees C and the detected wavelength was 254 nm. Amino acids derivative solution remained stable in 36 hours. The response was linear for 16 amino acids with a correlation coefficient r > 0.999 5. The average recoveries were 98.01% -101.8%. The method is reliable with good accuracy and repeatability, which is useful for the determination of amino acids in Galli Gigerii Endothelium Corneum. PMID:25039183

Liang, Kun; Zhang, Dan; Shi, Ji; Hu, Hong; Xiu, Yan-Feng; Jia, Tian-Zhu

2014-04-01

387

The experimental induction of hypophosphataemia in goats using anion exchange columns  

PubMed Central

1. Inorganic phosphate was selectively removed from the circulating blood of five anaesthetized goats by means of columns of anion-exchange resin. Concentrations of other ions were unaffected by the column. 2. Rates of inorganic phosphate extraction in excess of 5 m-moles/hr caused a fall in plasma inorganic phosphate of up to 50% in 30 min. 3. In four of the goats the calculated inorganic phosphate mobilization rate rose sharply to a maximum between 5.8 and 12.7 m-moles/hr and then fell progressively as more phosphate was removed. 4. During the course of the experiments a fall in blood pressure occurred, accompanied by a rise in blood glucose. The reasons for this are discussed. PMID:16992300

Symonds, H. W.; Treacher, R. J.

1967-01-01

388

The responses of goats to the experimental induction of hypocalcaemia with cation-exchange columns  

PubMed Central

1. Ionic calcium was selectively removed from the circulating blood of three anaesthetized goats by means of columns of cation-exchange resin. Concentrations of other ions were not directly affected by the column. 2. A calcium extraction rate of 0·35 m-equiv/min caused a fall in plasma total calcium of up to 40% in 35 min. Plasma calcium concentration returned to normal within 2 hr of the end of calcium removal. 3. Mobilization rates reached a maximum between 15 and 20 min after calcium removal commenced, declining rapidly after it had stopped. 4. Removal of calcium by EDTA infusion results in a similar calcium mobilization pattern to that produced by Ca removal by ion-exchange. 5. A smaller variation appears to exist between goats in maximum calcium mobilization rates than in maximum phosphorus mobilization rates and goats may be able to mobilize phosphorus relatively faster than calcium. PMID:16992313

Symonds, H. W.; Treacher, R. J.

1968-01-01

389

Supercritical Fluid Extraction- Process Simulation and Design  

E-print Network

of the simulation program, but is a reflection on our lack of good thennodynamic data to predict multicomponent flashes from high pressure to lower pressure for carbon dioxide/IPNwater systems. Further, the flash temperature is below the freezing point for water... of the column and is flashed to atmospheric pressure. The extract (solvent rich) stream, which now contains most of the IPA and some water, exits the top of the extractor. The extract is dropped in pressure (to 665 psia) and enters a decanter where any...

Martin, C. L.; Seibert, A. F.

390

Direct probing of chromatography columns by laser-induced fluorescence  

NASA Astrophysics Data System (ADS)

This report summarizes the progress and accomplishments of this research project from 1 Sep. 1989 to 28 Feb. 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe in supercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

McGuffin, V. L.

1992-12-01

391

Direct probing of chromatography columns by laser-induced fluorescence  

SciTech Connect

This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

McGuffin, V.L.

1992-12-07

392

Carrier-envelope phase drift measurement of picosecond pulses by an all-linear-optical means.  

PubMed

Carrier-envelope phase (CEP) drift of a pulse train of 2 ps pulses has been measured by a multiple beam interferometer. The round trip time of the interferometer is slightly mistuned from the pulse sequence, leading to spectral interference fringes. We extract the pulse-to-pulse CEP drift from the position of the spectral interference pattern. The length of the interferometer has been actively stabilized to ±10??nm, which sets the ultimate limit on the accuracy of the measurement to 78 mrad, while the CEP-drift (rms) noise of the measurement was 127 mrad (at 800 nm). PMID:25361118

Jójárt, P; Börzsönyi, A; Soskov, V; Zomer, F; Chiche, R; Cormier, E; Osvay, K

2014-10-15

393

Separation of uremic toxins from urine with resorcinarene-based ion chromatography columns.  

PubMed

People with chronic kidney disease suffer from uremic toxins which accumulate in their bodies. Detection and quantification of uremic toxins help diagnose kidney problems and start patient care. The aim of this research was to seek a new method to assist this diagnosis by trace level detection and separation of guanidine containing uremic toxins in water and urine. To detect and quantify the uremic toxins, new stationary phases for ion chromatography (IC) columns based on glutamic acid functionalized resorcinarenes bound to divinylbenzene macroporous resin were prepared. The new column packing material afforded separation of the five compounds: guanidinoacetic acid, guanidine, methylguanidine, creatinine, and guanidinobenzoic acid in 30min. Peak resolutions ranged from 7.6 to 1.3. Gradient elutions at ambient temperature with methanesulfonic acid (MSA) solution as eluent resulted in detection levels in water from 10 to 47ppb and in synthetic urine from 28 to 180ppb. Limits of quantification for the analytes using pulsed amperometric detection were 30-160ppb in water and 93-590ppb in urine. Trace levels of creatinine (1ppm) were detected in the urine of a healthy individual using the columns. PMID:25537175

Panahi, Tayyebeh; Weaver, Douglas J; Lamb, John D; Harrison, Roger G

2015-01-01

394

Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments  

SciTech Connect

In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry.

Yin, Jun; Haggerty, Roy; Stoliker, Deborah L.; Kent, Douglas B.; Istok, Jonathan D.; Greskowiak, Janek; Zachara, John M.

2011-04-05

395

Antioxidant Activity of Mulberry Fruit Extracts  

PubMed Central

Phenolic compounds were extracted from the fruits of Morus nigra and Morus alba using methanol and acetone. The sugar-free extracts (SFEs) were prepared using Amberlite XAD-16 column chromatography. All of the SFEs exhibited antioxidant potential as determined by ABTS (0.75–1.25 mmol Trolox/g), DPPH (2,2-diphenyl-1-picrylhydrazyl) (EC50 from 48 ?g/mL to 79 ?g/mL), and reducing power assays. However, a stronger activity was noted for the SFEs obtained from Morus nigra fruits. These extracts also possessed the highest contents of total phenolics: 164 mg/g (methanolic SFE) and 173 mg/g (acetonic SFE). The presence of phenolic acids and flavonoids in the extracts was confirmed using HPLC method and chlorogenic acid and rutin were found as the dominant phenolic constituents in the SFEs. PMID:22408465

Arfan, Muhammad; Khan, Rasool; Rybarczyk, Anna; Amarowicz, Ryszard

2012-01-01

396

Beam extraction from a synchrotron through a magnetic shield  

Microsoft Academic Search

A new beam extraction scheme from a synchrotron is put forward. The main difference from other schemes of extraction is the use of magnetic shields instead of a septum. Magnetic shields are located in the central dipole magnets of a pulsed chicane. The magnetic shield is a multilayer copper–iron tube. Numerical simulations and experimental results for the magnetic shield are

A. V. Bondarenko; N. A. Vinokurov

2009-01-01

397

Impedance measurements of the Spallation Neutron Source extraction kicker system  

Microsoft Academic Search

Transverse coupling impedance measurements of the Spallation Neutron Source (SNS) beam extraction system were performed and the results are here reported. The SNS beam extraction system is composed from 14 subsystems, each of which consists of a vertical kicker magnet plus a pulse forming network (PFN). Impedance bench measurements were performed on one large and one small aperture magnet, stand-alone

H. Hahn

2004-01-01

398

SNS EXTRACTION KICKER SYSTEM AND FIRST ARTICLE BPFN TEST  

Microsoft Academic Search

The Spallation Neutron Source (SNS) extraction kicker system brings the proton beam from the accumulator ring through a beam transfer line into the target area. The 14 kicker magnets are located in one straight section. The kicker magnets are energized by 14 Blumlein type Pulse Forming Networks (BPFN). The first article of the SNS extraction kicker BPFN was assembled and

J. MI; C. PAI; D. DAVINO; H. HAHN; R. LAMBIASE; Y. Y. LEE; W. MENG; J. SANDBERG; N. TSOUPAS; W. ZHANG; D. WARBURTON

2002-01-01

399

J-modulated ADEQUATE experiments using different kinds of refocusing pulses.  

PubMed

Owing to the recent developments concerning residual dipolar couplings (RDCs), the interest in methods for the accurate determination of coupling constants is renascenting. We intended to use the J-modulated ADEQUATE experiment by Kövér et al. for the measurement of (13)C - (13)C coupling constants at natural abundance. The use of adiabatic composite chirp pulses instead of the conventional 180 degrees pulses, which compensate for the offset dependence of (13)C 180 degrees pulses, led to irregularities of the line shapes in the indirect dimension causing deviations of the extracted coupling constants. This behaviour was attributed to coupling evolution, during the time of the adiabatic pulse (2 ms), in the J-modulation spin echo. The replacement of this pulse by different kinds of refocusing pulses indicated that a pair of BIPs (broadband inversion pulses), which behave only partially adiabatic, leads to correct line shapes and coupling constants conserving the good sensitivity obtained with adiabatic pulses. PMID:17729234

Thiele, Christina M; Bermel, Wolfgang

2007-10-01

400

Double-pulse excitation of x-ray capillary lasers  

NASA Astrophysics Data System (ADS)

We propose to enhance the gain of Ne-like ion capillary lasers by the utilization of two discharge pulses. A first pulse working in the pinch regime mode is designed to create the cold-plasma column with the required ionization degree, followed by a second fast high-voltage pulse to do the effective collision excitation. The second pulse, which heats the electrons to a kinetic temperature Te greater than Tecold in times shorter than the ionization time, increases the laser gain. In the two stage pumping scheme, both the amplitude of each of the pulses and the delay between them can be adjusted for independent control of the ionization degree and excitation rate. Numerical estimations performed for the low-Z-ion (Na+1, . . ., Ar+8) lasers with the double pulse pumping predict enhancement in gain by a factor of approximately 10. In addition, the extension of two-stage electrical pumping to the high-Z-ion collision and recombination laser schemes is discussed. Description of the experimental set-up constructed for such experiments and some related measurement data are also presented.

Kukhlevsky, Sergei V.; Kozma, Ida Z.; Palladino, Libero; Reale, Armando; Flora, Francesco; Mezi, Luca; Giordano, Gualtiero

1997-11-01

401

Comparison of automated pre-column and post-column analysis of amino acid oligomers  

NASA Technical Reports Server (NTRS)

It has been shown that various amino acids will polymerize under plausible prebiotic conditions on mineral surfaces, such as clays and soluble salts, to form varying amounts of oligomers (n = 2-6). The investigations of these surface reactions required a quantitative method for the separation and detection of these amino acid oligomers at the picomole level in the presence of nanomole levels of the parent amino acid. In initial high-performance liquid chromatography (HPLC) studies using a classical postcolumn o-phthalaldehyde (OPA) derivatization ion-exchange HPLC procedure with fluorescence detection, problems encountered included lengthy analysis time, inadequate separation and large relative differences in sensitivity for the separated species, expressed as a variable fluorescent yield, which contributed to poor quantitation. We have compared a simple, automated, pre-column OPA derivatization and reversed-phase HPLC method with the classical post-column OPA derivatization and ion-exchange HPLC procedure. A comparison of UV and fluorescent detection of the amino acid oligomers is also presented. The conclusion reached is that the pre-column OPA derivatization, reversed-phase HPLC and UV detection produces enhanced separation, improved sensitivity and faster analysis than post-column OPA derivatization, ion-exchange HPLC and fluorescence detection.

Chow, J.; Orenberg, J. B.; Nugent, K. D.

1987-01-01

402

Heat Transfer Analysis for a Fixed CST Column  

SciTech Connect

In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, a transient two-dimensional heat transfer model that includes the conduction process neglecting the convection cooling mechanism inside the crystalline silicotitanate (CST) column has been constructed and heat transfer calculations made for the present design configurations. For this situation, a no process flow condition through the column was assumed as one of the reference conditions for the simulation of a loss-of-flow accident. A series of the modeling calculations has been performed using a computational heat transfer approach. Results for the baseline model indicate that transit times to reach 130 degrees Celsius maximum temperature of the CST-salt solution column are about 96 hours when the 20-in CST column with 300 Ci/liter heat generation source and 25 degrees Celsius initial column temperature is cooled by natural convection of external air as a primary heat transfer mechanism. The modeling results for the 28-in column equipped with water jacket systems on the external wall surface of the column and water coolant pipe at the center of the CST column demonstrate that the column loaded with 300 Ci/liter heat source can be maintained non-boiling indefinitely. Sensitivity calculations for several alternate column sizes, heat loads of the packed column, engineered cooling systems, and various ambient conditions at the exterior wall of the column have been performed under the reference conditions of the CST-salt solution to assess the impact of those parameters on the peak temperatures of the packed column for a given transient time. The results indicate that a water-coolant pipe at the center of the CST column filled with salt solution is the most effective one among the potential design parameters related to the thermal energy dissipation of decay heat load. It is noted that the cooling mechanism at the wall boundary of the column has significant impact on maximum and wall temperatures of the column. In addition, the results computed by the present model were verified by the theoretical results. The analysis results will provide quantitative information associated with the process heat control and management of the CST base design. For example, transient responses of the CST system under a loss-of-flow accident condition will provide safety design information for an emergency cooling system of the column.

Lee, S.Y.

2004-02-19

403

Simultaneous extraction and separation of liquiritin, glycyrrhizic acid, and glabridin from licorice root with analytical and preparative chromatography  

Microsoft Academic Search

Simultaneous extraction and separation of liquiritin, glycyrrhizic acid, and glabridin from licorice were developed by liquidliquid\\u000a extraction with liquid chromatography separation. By utilizing different extraction solvents, procedures, and times, the optimum\\u000a extraction conditions were established. The extracts of licorice were separated and determined using a C18 column with a mobile phase consisting of acetonitrile-water (containing 1.0% acetic acid) with a

Minglei Tian; Hongyuan Yan; Kyung Ho Row

2008-01-01

404

Sweet and Sour: Attenuating Sulfidogenesis in an Advective Flow Column System with Perchlorate or Nitrate Treatment  

NASA Astrophysics Data System (ADS)

Hydrogen sulfide (H2S) biogenesis in oil reservoirs is a primary cause of souring and of associated costs in reservoir and pipeline maintenance. In addition to the corrosive effects of the H2S itself, abiotic and biological oxidation also generates sulfuric acid, further degrading metallic surfaces. Amending these environments with perchlorate (ClO4-) resolves these problems by inhibition of biological sulfate reduction and re-oxidation of H2S to elemental sulfur by dissimilatory (per)chlorate reducing bacteria (DPRB). Triplicate flow through columns packed with San Francisco bay sediment were flushed with bay water ([SO4=] = 25-30 mM) containing yeast extract with 50 mM inhibitor concentrations (NO3-or ClO4-) decreasing to 25 mM and finally 12.5 mM. Influent and effluent geochemistry was monitored and DNA was prepared from the sediment bed for microbial community analysis. Souring was reversed by both treatments (at 50 mM) compared to the control columns that had no ion addition. Nitrate began to re-sour when treatment concentration was decreased to 25 mM but treatment had to be decreased to 12.5 mM before the perchlorate treated columns began to re-sour. However, the treated columns re-soured to a lesser extent than the control columns. Phylochip microbial community analyses indicated microbial community shifts and phylogenetic clustering by treatment. Isotopic analysis of sulfate showed trends that broadly agreed with the geochemistry but also suggested further sulfur cycling was occurring. This study indicates that perchlorate shows great promise as an inhibitor of sulfidogenesis in natural communities and provides insight into which organisms are involved in this process.

Engelbrektson, A. L.; Hubbard, C. G.; Piceno, Y.; Boussina, A.; Jin, Y.; Dubinsky, E. A.; Tom, L.; Hu, P.; Conrad, M. E.; Anderson, G. L.; Coates, J. D.

2013-12-01

405

Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns  

SciTech Connect

Two prototype Thermal Cycling Absorption Process (TCAP) columns have been metallurgically examined after retirement, to determine the causes of failure and to evaluate the performance of the column container materials in this application. Leaking of the fluid heating and cooling subsystems caused retirement of both TCAP columns, not leaking of the main hydrogen-containing column. The aluminum block design TCAP column (ABL block TCAP) used in the Advanced Hydride Laboratory, Building 773-A, failed in one nitrogen inlet tube that was crimped during fabrication, which lead to fatigue crack growth in the tube and subsequent leaking of nitrogen from this tube. The Third Generation stainless steel design TCAP column (Third generation TCAP), operated in 773-A room C-061, failed in a braze joint between the freon heating and cooling tubes (made of copper) and the main stainless steel column. In both cases, stresses from thermal cycling and local constraint likely caused the nucleation and growth of fatigue cracks. No materials compatibility problems between palladium coated kieselguhr (the material contained in the TCAP column) and either aluminum or stainless steel column materials were observed. The aluminum-stainless steel transition junction appeared to be unaffected by service in the AHL block TCAP. Also, no evidence of cracking was observed in the AHL block TCAP in a location expected to experience the highest thermal shock fatigue in this design. It is important to limit thermal stresses caused by constraint in hydride systems designed to work by temperature variation, such as hydride storage beds and TCAP columns.

Clark, E.A.

1992-11-21

406

Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns  

SciTech Connect

Two prototype Thermal Cycling Absorption Process (TCAP) columns have been metallurgically examined after retirement, to determine the causes of failure and to evaluate the performance of the column container materials in this application. Leaking of the fluid heating and cooling subsystems caused retirement of both TCAP columns, not leaking of the main hydrogen-containing column. The aluminum block design TCAP column (AHL block TCAP) used in the Advanced Hydride Laboratory, Building 773-A, failed in one nitrogen inlet tube that was crimped during fabrication, which lead to fatigue crack growth in the tube and subsequent leaking of nitrogen from this tube. The Third Generation stainless steel design TCAP column (Third generation TCAP), operated in 773-A room C-061, failed in a braze joint between the freon heating and cooling tubes (made of copper) and the main stainless steel column. In both cases, stresses from thermal cycling and local constraint likely caused the nucleation and growth of fatigue cracks. No materials compatibility problems between palladium coated kieselguhr (the material contained in the TCAP column) and either aluminum or stainless steel column materials were observed. The aluminum-stainless steel transition junction appeared to be unaffected by service in the AHL block TCAP. Also, no evidence of cracking was observed in the AHL block TCAP in a location expected to experience the highest thermal shock fatigue in this design. It is important to limit thermal stresses caused by constraint in hydride systems designed to work by temperature variation, such as hydride storage beds and TCAP columns.

Clark, E.A.

1992-11-21

407

Pulse measurement apparatus and method  

DOEpatents

An embodiment of the invention is directed to a pulse measuring system that measures a characteristic of an input pulse under test, particularly the pulse shape of a single-shot, nano-second duration, high shape-contrast optical or electrical pulse. An exemplary system includes a multi-stage, passive pulse replicator, wherein each successive stage introduces a fixed time delay to the input pulse under test, a repetitively-gated electronic sampling apparatus that acquires the pulse train including an entire waveform of each replica pulse, a processor that temporally aligns the replicated pulses, and an averager that temporally averages the replicated pulses to generate the pulse shape of the pulse under test. An embodiment of the invention is directed to a method for measuring an optical or an electrical pulse shape. The method includes the steps of passively replicating the pulse under test with a known time delay, temporally stacking the pulses, and temporally averaging the stacked pulses. An embodiment of the invention is directed to a method for increasing the dynamic range of a pulse measurement by a repetitively-gated electronic sampling device having a rated dynamic range capability, beyond the rated dynamic range of the sampling device; e.g., enhancing the dynamic range of an oscilloscope. The embodied technique can improve the SNR from about 300:1 to 1000:1. A dynamic range enhancement of four to seven bits may be achieved.

Marciante, John R. (Webster, NY); Donaldson, William R. (Pittsford, NY); Roides, Richard G. (Scottsville, NY)

2011-10-25

408

Photonic generation of UWB pulses with pulse position modulation  

E-print Network

Photonic generation of UWB pulses with pulse position modulation H. Mu and J. Yao A novel photonic approach to generating ultra-wideband (UWB) signals with pulse position modulation (PPM) is proposed-position-modu- lation module to achieve PPM. When a Gaussian pulse train is inputted to the first subsystem, a monocycle

Yao, Jianping

409

Fault tolerant pulse synchronization  

E-print Network

global time. Previous researchers have proposed the Reachback Firefly algorithm for pulse synchronization, in which nodes react to the firings of other nodes by changing their period. We propose an extension to this algorithm for tolerating arbitrary...

Deconda, Keerthi

2009-05-15

410

Pulse Coil Tester  

NASA Technical Reports Server (NTRS)

Set of relays tested easily and repeatedly. Pulse coil tester causes coil under test to generate transient voltage; waveform indicates condition of coil. Tester accommodates assembly of up to four coils at a time.

Simon, Richard A.

1988-01-01

411

Pulsed-neutron monochromator  

DOEpatents

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Mook, Jr., Herbert A. (Oak Ridge, TN)

1985-01-01

412

Pulsed-neutron monochromator  

DOEpatents

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Mook, H.A. Jr.

1984-01-01

413

Drinking Straw Pulse Measurer  

NSDL National Science Digital Library

In this health activity, learners create a device so that they not only feel their heartbeat, but also see it, using a straw and some clay. Learners calculate their pulse rate (beats per minute) while at rest and after exercise.

Boston, Wgbh

2003-01-01

414

Digital pulse processing  

E-print Network

This thesis develops an exact approach for processing pulse signals from an integrate-and-fire system directly in the time-domain. Processing is deterministic and built from simple asynchronous finite-state machines that ...

McCormick, Martin (Martin Steven)

2012-01-01

415

Pulsed spallation neutron sources  

SciTech Connect

This paper reviews the early history of pulsed spallation neutron source development ar Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provide a few examples of applications in fundamental condensed matter physics, materials science and technology.

Carpenter, J.M. [Argonne National Lab., IL (United States). Intense Pulsed Neutron Source Div.

1996-05-01

416

Pulse magnetic welder  

DOEpatents

A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.

Christiansen, D.W.; Brown, W.F.

1984-01-01

417

Pulse oximetry: fundamentals and technology update  

PubMed Central

Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD) of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs) or more in 5% of the examinations, which is in accordance with an error of 3%–4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns can be attributed to the empirical calibration process, which is performed on healthy volunteers. Other limitations of pulse oximetry include the presence of dyshemoglobins, which has been addressed by multiwavelength pulse oximetry, as well as low perfusion and motion artifacts that are partially rectified by sophisticated algorithms and also by reflection pulse oximetry. PMID:25031547

Nitzan, Meir; Romem, Ayal; Koppel, Robert

2014-01-01

418

Ewing's sarcoma of the vertebral column  

SciTech Connect

Twenty-two patients with vertebral primaries were registered in the Intergroup Ewing's Sarcoma Study between 1973 and 1977. The radiation doses to the primary tumors ranged between 3800 and 6200 rad. All patients received intensive combination chemotherapy. After a followup ranging between 14 and 62 months, 14 patients remained disease-free. All patients with primary tumor of the cervical and dorsal spine remained disease-free. Of eight patients with lesions in the distal spine, (sacrococcygeal region) six developed recurrence, in three a local recurrence was observed despite doses of 6000 rad or higher. Doses of 5000 rad or less (in addition to combination chemotherapy as used in the Intergroup Ewing's Study) appear adequate in controlling the primary tumors of the proximal segments of the spinal column.

Pilepich, M.V. (Washington Univ. School of Medicine, St. Louis, MO); Vietti, T.J.; Nesbit, M.E.; Tefft, M.; Kissane, J.; Burgert, O.; Pritchard, D.; Gehan, E.A.

1981-01-01

419

Earth Remote Sensing: A Column Closure Approach  

NASA Technical Reports Server (NTRS)

Entering the new millennium, there is no doubt that scientists expand greatly their scientific knowledge of the Earth system by utilizing unique capabilities from the vantage points of space. These global satellite observations include the NASA/NOAA Pathfinder and other ongoing data analysis projects, the Earth Observing System (EOS) program, the Earth System Science Pathfinders (ESSP) small research satellite missions, multi-agency planning for the National Polar-orbiting Operational Environmental Satellite (NPOESS), and other international satellite missions. However, using satellite remotely sensed data alone cannot explore fully the physical processes and energetic balance involved in our changing climate. To close the loop, the ground-based remote sensing and airborne in situ measurements are required. This talk provides an overview of the general strategy of Earth remote sensing for a column closure approach and discusses necessary instrumentation.

Tsay, Si-Chee; Lau, William (Technical Monitor)

2001-01-01

420

Local stresses in the Janssen granular column  

NASA Astrophysics Data System (ADS)

We study experimentally the distribution of local stresses in a granular material confined inside a vertical cylinder. We use an image correlation technique to measure the displacement field of the container induced by the forces exerted by the grains on the inner wall. We describe an optimization procedure based on the linear theory of elastic shells to deduce the distribution of these forces from the measured displacement field. They correspond to the stress field of the granular material close to the container's inner wall. We first confirm the validity of Janssen's description for various experiments, including the influence of the bead diameter and the effect of an additional mass on top of the granular column. We then apply this method to determine the stress field during the gravity-driven discharge of a silo through an aperture.

Cambau, Thomas; Hure, Jérémy; Marthelot, Joël

2013-08-01

421

Hypertrophic Columns of Bertin: Imaging Findings  

PubMed Central

Hypertrophic column of Bertin (HCB) may mimic renal mass and may lead to unnecessary nephrectomy in some conditions. In this case report we present a patient with HCB, which mimics renal mass in ultrasonography (US) examination with its US, Doppler US and magnetic resonance imaging (MRI) findings. In contrast to the US, excretory urography (EU) and computed tomography (CT) findings of HCB, MRI findings of this entity could not take part in the literature sufficiently. We suggest that this case report could be useful in preventing the unnecessary biopsy and surgical procedures. In conclusion, however, US is often sufficient in the diagnosis of HCB, unusual lesions could be seen. In the final diagnosis of these lesions, MRI is very useful and more responsive technique. Understanding the imaging characteristics of HCB could prevent unnecessary interventional or surgical procedures. PMID:25610298

Algin, Oktay; Ozmen, Evrim; Gumus, Mehmet

2014-01-01

422

The vertebral column of Australopithecus sediba.  

PubMed

Two partial vertebral columns of Australopithecus sediba grant insight into aspects of early hominin spinal mobility, lumbar curvature, vertebral formula, and transitional vertebra position. Au. sediba likely possessed five non-rib-bearing lumbar vertebrae and five sacral elements, the same configuration that occurs modally in modern humans. This finding contrasts with other interpretations of early hominin regional vertebral numbers. Importantly, the transitional vertebra is distinct from and above the last rib-bearing vertebra in Au. sediba, resulting in a functionally longer lower back. This configuration, along with a strongly wedged last lumbar vertebra and other indicators of lordotic posture, would have contributed to a highly flexible spine that is derived compared with earlier members of the genus Australopithecus and similar to that of the Nariokotome Homo erectus skeleton. PMID:23580532

Williams, Scott A; Ostrofsky, Kelly R; Frater, Nakita; Churchill, Steven E; Schmid, Peter; Berger, Lee R

2013-04-12

423

Micro-column plasma emission liquid chromatograph  

DOEpatents

In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

Gay, Don D. (Aiken, SC)

1984-01-01

424

Antioxidant compounds from coriander ( Coriandrum sativum L.) etheric extract  

Microsoft Academic Search

Five fractions (?-carotene, ?-cryptoxanthin epoxide, lutein-5,6-epoxide, violaxanthin and neoxanthin) were isolated from a coriander ether extract using column chromatography and identified according to their chromatographic and spectral characteristics. No significant differences were noted with regard to their antioxidant properties using the ?-carotene\\/linoleic acid model, however they were inferior to the BHT and the crude etheric extract. The ?-carotene component represented

Nonete Barbosa Guerra; Enayde de Almeida Melo; Jorge Mancini Filho

2005-01-01

425

Temperature-compensated 8-bit column driver for AMLCD  

NASA Astrophysics Data System (ADS)

An all-digital, 5 V input, 50 Mhz bandwidth, 10-bit resolution, 128- column, AMLCD column driver IC has been designed and tested. The 10-bit design can enhance display definition over 6-bit nd 8-bit column drivers. Precision is realized with on-chip, switched-capacitor DACs plus transparently auto-offset-calibrated, opamp outputs. Increased resolution permits multiple 10-bit digital gamma remappings in EPROMs over temperature. Driver IC features include externally programmable number of output column, bi-directional digital data shifting, user- defined row/column/pixel/frame inversion, power management, timing control for daisy-chained column drivers, and digital bit inversion. The architecture uses fewer reference power supplies.

Dingwall, Andrew G. F.; Lin, Mark L.

1995-06-01

426

Pulsed power for electric guns  

Microsoft Academic Search

Pulsed power requirements for electric guns are described and preferred technologies for energy storage and pulse compression are discussed. Primary approaches are rotating machines and capacitor based, pulse-forming networks, but alternative technologies that may offer some operational benefits are also discussed. These include linear magnetic flux compressors, cryogenically cooled, high-temperature superconducting inductors, novel dielectrics for energy storage, and pulsed magnetohydrodynamic

Ian R. McNab

1997-01-01

427

Microbial Transformation of 2,4,6-Trinitrotoluene in Aerobic Soil Columns  

PubMed Central

2,4,6-Trinitrotoluene (TNT)-contaminated soil material of a former TNT production plant was percolated aerobically in soil columns. Nineteen days of percolation with a potassium phosphate buffer supplemented with glucose or glucose plus ammonium sulfate caused an over 90% decline in the amount of extractable nitroaromatics in soils containing 70 to 2,100 mg of TNT per kg (dry weight). In the percolation solution, a complete elimination of TNT was achieved. Mutagenicity and soil toxicity were significantly reduced by the percolation process. 4-N-Acetylamino-2-amino-6-nitrotoluene was generated in soil and percolation fluid as a labile TNT metabolite. PMID:16535369

Bruns-Nagel, D.; Breitung, J.; von Low, E.; Steinbach, K.; Gorontzy, T.; Kahl, M.; Blotevogel, K.; Gemsa, D.

1996-01-01

428

Ni–C powder synthesis by a submerged pulsed arc in breakdown mode  

Microsoft Academic Search

Powders of Ni–C nanoparticles were synthesized using a pulsed arc between Ni electrodes submerged in pure ethanol. The arc was ignited by inter-electrode breakdown. The ethanol was arc treated for 5min with 1?s duration pulses, at a repetition rate of ?1kHz. The pulse energy was in a range of 0.01–0.05J. Powder samples were obtained by extracting liquid from the treatment

N. Parkansky; G. Frenkel; B. Alterkop; I. Beilis; R. L. Boxman; Z. Barkay; Yu. Rosenberg

2008-01-01

429

Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams  

Microsoft Academic Search

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity, low-permeability and high adsorption\\u000a of coal seams. The pulsed mechanism of a high-pressure pulsed water jet was studied through theoretical analysis, experiment\\u000a and field measurement. The results show that high-pressure pulsed water jet has three dynamic properties. What’s more, the\\u000a three dynamic effects can be found

Xiao-hong Li; Dong-ping Zhou; Yi-yu Lu; Yong Kang; Yu Zhao; Xiao-chuan Wang

2009-01-01

430

Self-heating of Pu-238 anion exchange column  

SciTech Connect

Heat and mass transfer calculations were performed to determine the effect of increases in the H-canyon Frames Waste Recovery (FWR) column loading on column temperatures during flow interruptions. The heat transfer calculations are based on a previous analysis of the H Frames columns, and the mass transfer calculations use data from two recent laboratory elutions. The current Technical Standard (TS) limits the total amount of Pu-238 on the column to 490 g. To meet production goals for NASA`s Cassini mission, this limit needs to be increased. In addition to the loading limit, the TS stipulates that column temperatures cannot exceed 60{degrees}C. Significant column heating occurs only when flow to the column is interrupted. During normal operation, column temperatures are approximately equal to the ambient temperature. Results from the laboratory elutions and the heat and mass transfer analyses show that, for an ambient temperature of 30{degrees}C, the maximum column temperature cannot reach the TS limit of 60{degrees}C until 80 min. after flow is interrupted during loading or washing or until 50 min. after flow is interrupted during elution. These times are independent of operating conditions. The heating rate for loading and washing was calculated assuming adiabatic heating at a maximum adsorbed plutonium concentration of 45 g/L. The heating rate for elution is based on adiabatic hearing at a total plutonium concentration of 71 g/L. The maximum total concentration during elution consists of 45 g/L adsorbed plutonium plus 26 g/L dissolved plutonium in equilibrium with the adsorbed solid. Based on the results of this study and the previous analysis of the H Frames columns, it is safe to raise the Pu-238 loading of the FWR column from 490 to 800 g or more without violating the TS column temperature limit of 60{degrees}C during a 15-min. flow interruption.

Laurinat, J.E.

1994-03-23

431

The Microbial World: Winogradsky Column- Perpetual Life in a Tube  

NSDL National Science Digital Library

This Winogradsky column web page is designed to teach undergraduate students a simple model system of nutrient cycling in natural waters. It includes a physical description of the column and explains how the column can be used to demonstrate metabolic diversity of prokaryotes, how microorganisms occupy highly specific microsites according to their environmental tolerances and their carbon and energy requirements, and how mineral elements are cycled in natural environments. Artistic illustrations and images illustrate the interdependent roles of microorganisms.

Deacon, Jim; Biology, The U.

432

Fluid column stability in the presence of periodic accelerations  

NASA Technical Reports Server (NTRS)

The interface stability of fluid columns in the presence of a periodic acceleration field with a component normal to the longitudinal axis of the isothermal cylinder was investigated. Floquet theory was used in the investigation and the column was taken as infinite. The finite length case was also studied and axisymmetric and nonaxisymmetric oscillations were considered. Results for the infinite length case were good approximations to those for the finite length column.

Lyell, M. J.

1993-01-01

433

Improved column preparation and performance in capillary electrochromatography  

Microsoft Academic Search

Problems encountered in capillary electrochromatography, i.e. non-reproducible column manufacture, bubble formation during usage, short column lifetimes and limited choice of packing particles are addressed by the development of fritless or single-frit, internally tapered, segmented and dead-volume free coupled capillary columns. The Van Deemter plots measured demonstrate the performance of these high-quality capillaries which are suitable for capillary electrochromatography as well

Erdmann Rapp; Ernst Bayer

2000-01-01

434

Improved column preparation and performance in capillary electrochromatography.  

PubMed

Problems encountered in capillary electrochromatography, i.e. non-reproducible column manufacture, bubble formation during usage, short column lifetimes and limited choice of packing particles are addressed by the development of fritless or single-frit, internally tapered, segmented and dead-volume free coupled capillary columns. The Van Deemter plots measured demonstrate the performance of these high-quality capillaries which are suitable for capillary electrochromatography as well as for capillary high-performance liquid chromatographic applications. PMID:10961327

Rapp, E; Bayer, E

2000-07-28

435

Heat transfer investigations in a slurry bubble column  

Microsoft Academic Search

Slurry bubble columns, for use in Fisher-Tropsch synthesis, have been investigated. Two bubble columns (0.108 and 0.305 m internal diameter) were set up and experiments were conducted to determine gas holdup and heat transfer coefficients. These columns were equipped with either single heat transfer probes of different diameters, or bundles of five-, seven- or thirty-seven tubes. The experiments were conducted

S. C. Saxena; N. S. Rao; R. Vadivel; S. Shrivastav; A. C. Saxena; B. B. Patel; P. R. Thimmapuram; M. Y. Kagzi; I. A. Khan; A. K. Verma

1991-01-01

436

Heat transfer investigations in a slurry bubble column  

Microsoft Academic Search

Slurry bubble columns, for use in Fischer-Tropsch synthesis, have been investigated. Two bubble columns (0.108 and 0.305 m internal diameter) were set up and experiments were conducted to determine gas holdup and heat transfer coefficients. These columns were equipped with either single heat transfer probes of different diameters, or bundles of five-, seven-, or thirty-seven tubes. the experiments were conducted

S. C. Saxena; N. S. Rao; R. Vadivel; S. Shrivastav; A. C. Saxena; B. B. Patel; P. R. Thimmapuram; M. Y. Kagzi; I. A. Khan; A. K. Verma

1991-01-01

437

A 100MeV Injector Racetrack Microtron for the MAX Storage-Ring\\/Pulse-Stretcher  

Microsoft Academic Search

A 100 MeV pulsed race-track microtron (RTM) has been in operation at the University of Lund since 1979Âą. The RTM will now be used as an injector for a storage-ring\\/pulse-stretcher currently being built. The RTM with its injection, acceleration and extraction systems are described and the beam characteristics are discussed.

M. Eriksson

1983-01-01

438

Separation optimization of long porous-layer open-tubular columns for nano-LC-MS of limited proteomic samples.  

PubMed

The single-run resolving power of current 10 ?m id porous-layer open-tubular (PLOT) columns has been optimized. The columns studied had a poly(styrene-co-divinylbenzene) porous layer (~0.75 ?m thickness). In contrast to many previous studies that have employed complex plumbing or compromising set-ups, SPE-PLOT-LC-MS was assembled without the use of additional hardware/noncommercial parts, additional valves or sample splitting. A comprehensive study of various flow rates, gradient times, and column length combinations was undertaken. Maximum resolution for <400 bar was achieved using a 40 nL/min flow rate, a 400 min gradient and an 8 m long column. We obtained a 2.3-fold increase in peak capacity compared to previous PLOT studies (950 versus previously obtained 400, when using peak width = 2? definition). Our system also meets or surpasses peak capacities obtained in recent reports using nano-ultra-performance LC conditions or long silica monolith nanocolumns. Nearly 500 proteins (1958 peptides) could be identified in just one single injection of an extract corresponding to 1000 BxPC3 beta catenin (-/-) cells, and ~1200 and 2500 proteins in extracts of 10,000 and 100,000 cells, respectively, allowing detection of central members and regulators of the Wnt signaling pathway. PMID:23813982

Rogeberg, Magnus; Vehus, Tore; Grutle, Lene; Greibrokk, Tyge; Wilson, Steven Ray; Lundanes, Elsa

2013-09-01

439

Pulse shaping with transmission lines  

DOEpatents

A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

Wilcox, R.B.

1985-08-15

440

Pulse shaping with transmission lines  

DOEpatents

A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

Wilcox, Russell B. (Oakland, CA)

1987-01-01

441

Efficient optical pulse stacker system  

DOEpatents

Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

Seppala, Lynn G. (Pleasanton, CA); Haas, Roger A. (Pleasanton, CA)

1982-01-01

442

Separation and identification of phenolic compounds in canned artichoke by LC/DAD/ESI-MS using core-shell C18 column: a comparative study.  

PubMed

Core-shell silica stationary phase was considered as a breakthrough in column technology in HPLC world. In this work, the chromatographic performance of core-shell column, made by fusing a 0.5?m porous silica layer onto 1.7?m nonporous silica cores, was compared with sub-2?m fully porous particle materials for separation and identification of phenolic compounds in canned artichoke heads. The anti-oxidant caffeoylquinic acids of artichoke extract was taken as representative for calculating the plate heights in a wide flow rate range and analyzed on the basis of the van Deemter and Knox equations. Theoretical Poppe plots were constructed for each column to compare their kinetic performance. Both phases gave similar minimum plate heights when using non-reduced coordinates. Meanwhile, the flat C-term of core-shell column provided the possibilities for applying high flow rates without significant loss in efficiency. In addition, the peak capacities of both columns were measured, at constant chromatographic linear velocity and intrinsic gradient steepness, in order to generate comparable retention window for the least and the most retained compounds. Finally, the core-shell column was successfully applied for separation and identification of 10 phenolic compounds in canned artichoke extracts by liquid chromatography-diode array detection-tandem mass spectrometry, exhibiting great potential in the field of food analysis. PMID:23266111

Wu, Jianbing; Qian, Yongsheng; Mao, Peipei; Chen, Linyao; Lu, Yanbin; Wang, Huizhong

2013-05-15

443

The Nature of Stresses in a Giant Static Granular Column  

NASA Astrophysics Data System (ADS)

We systematically investigate the mean pressure measurements at the bottom of a giant static granular column. If a constant overload is placed on top of the bed, the pressure observed displays linearity in overload and nonmonotonic in column height. This result is in contradiction with the classical Janssen model. However it is in good agreement with the oriented stress linearity (OSL) model which reveals a local, linear relation between stress components. We conclude that the OSL model works well not only in a tiny static granular column but also in a giant static granular column.

Ge, Bao-Liang; Shi, Qing-Fan; Ram, Chand; He, Jian-Feng; Ma, Shao-Peng

2013-04-01

444

Halo columns: new generation technology for high speed liquid chromatography.  

PubMed

Fast speed and high sample loading and the pressing demands of industries and researchers are compelling scientists and manufacturers to explore the new horizons in column technology. Recently, superficially porous silica particle columns are manufactured with some salient features such as super fast speed, sharp peaks, good sample loading, and low backpressure. The commercially available columns are Halo (Advanced Material Technology, Wilmington, DE), Express (Supelco, Bellefonte, PA), and Proshell 120 (Agilent, Santa Clara, CA). Halo columns are of C(8), C(18), RP Amide, and HILIC types with 2.7 microm over all diameters, 0.5 microm porous thick layers containing 90 A as pore diameter, and 150 m(2)/g surface area. These columns have been used for fast separation of low molecular weight compounds with some exception for large molecules such as protein, peptides, and DNA. The present article describes the importance of these state-of-the-art superficially porous silica particles based columns with special emphasis on Halo columns. The different aspects of these columns such as structures, mechanism of separations, applications, and comparison, with conventional columns have been discussed. PMID:20515534

Ali, Imran; Gaitonde, Vinay D; Grahn, Anders

2010-01-01

445

Optimum geometry of tuned liquid column-gas damper for control of offshore jacket platform vibrations under seismic excitation  

NASA Astrophysics Data System (ADS)

In this study, the effectiveness of a tuned liquid column-gas damper, TLCGD, on the suppression of seismicinduced vibrations of steel jacket platforms is evaluated. TLCGD is an interesting choice in the case of jacket platforms because it is possible to use the structural elements as the horizontal column of the TLCGD. The objective here is to find the optimum geometric parameters, namely orientation and configuration of vertical columns, length ratio, and area ratio of the TLCGD, considering nonlinear damping of the TLCGD and water-structure interaction between the jacket platform and sea water. The effects of different characteristics of ground motion such as PGA and frequency content on the optimum geometry are also investigated and it is observed that these features have some influence on the optimum area ratio. Finally it is observed that pulse arrangement of ground acceleration is one of the most important parameters affecting the efficiency of a TLCGD. In other words, it is found that the TLCGD's capability to reduce the RMS responses depends only on the frequency content of the ground acceleration, but its capability to reduce the maximum responses depends on both the frequency content and the pulse arrangement of the ground acceleration.

Mousavi, Seyed Amin; Zahrai, Seyed Mehdi; Bargi, Khosrow

2012-12-01

446

Photoconductive circuit element pulse generator  

DOEpatents

A pulse generator for characterizing semiconductor devices at millimeter wavelength frequencies where a photoconductive circuit element (PCE) is biased by a direct current voltage source and produces short electrical pulses when excited into conductance by short laser light pulses. The electrical pulses are electronically conditioned to improve the frequency related amplitude characteristics of the pulses which thereafter propagate along a transmission line to a device under test.

Rauscher, Christen (Alexandria, VA)

1989-01-01